Danfoss VACON NXP Air Cooled Installation Guide

Installation Guide for Danfoss models including: VACON NXP Air Cooled, VACON, NXP Air Cooled, Air Cooled, Cooled

VACON Hybridization Design Guide

3.8 MB

VACON NXP Air Cooled | Danfoss

File Info : application/pdf, 51 Pages, 836.02KB

AJ361178777743en-000101

vacon® nx
ac drives
design guide hybridization

vacon · 1
TABLE OF CONTENTS
Document ID:DPD01887 Revision release date: 24.10.2016
1. BASICS ........................................................................................................................ 2
1.1 Power or energy storage....................................................................................................... 3 1.2 Battery current dimensioning............................................................................................... 5
2. BASIC TOPOLOGIES FOR CONNECTION ....................................................................... 6 3. SPECIAL CHARACTERISTICS AFFECTING THE SELECTION ......................................... 8
3.1 Voltage window...................................................................................................................... 8 3.2 Galvanic isolation requirement........................................................................................... 11 3.3 Balance or maintenance charge......................................................................................... 14 3.4 System control principles ................................................................................................... 15
4. CHOOSING A CORRECT TOPOLOGY............................................................................ 17
4.1 Allowed topology configurations......................................................................................... 18
5. BASIC VARIANTS....................................................................................................... 19
5.1 Direct to DC ......................................................................................................................... 19 5.1.1 Control structure .................................................................................................. 20
5.2 DC to DC .............................................................................................................................. 22 5.2.1 Filter...................................................................................................................... 22 5.2.2 Control Structure .................................................................................................. 34
6. PRODUCT CONFIGURATION EXAMPLES .................................................................... 36
6.1 Scope of delivery ................................................................................................................. 36 6.1.1 Direct to DC ........................................................................................................... 36 6.1.2 DC to DC ................................................................................................................ 37
6.2 Example configurations ...................................................................................................... 39 6.2.1 DC/DC for supply interruptions ............................................................................ 39 6.2.2 Direct DC for Grid Support.................................................................................... 40
7. SIZING OF THE SYSTEM AND PRODUCT .................................................................... 41
7.1 Direct to DC ......................................................................................................................... 41 7.2 DC/DC .................................................................................................................................. 42
8. INFORMATION TO ACQUIRE FROM CUSTOMERS ....................................................... 47
NOTE! You can download the English and French product manuals with applicable safety, warning and caution information from http://drives.danfoss.com/knowledge-center/technical-documentation/. REMARQUE Vous pouvez télécharger les versions anglaise et française des manuels produit contenant l'ensemble des informations de sécurité, avertissements et mises en garde applicables sur le site http://drives.danfoss.com/knowledge-center/technical-documentation/ .
24-hour support +358 (0)201 212 575 · Email: service@vacon.com

vacon · 2

BASICS

1. BASICS
The basic idea is always to achieve energy and/or power management of Common Point of Coupling. Typical use cases are
· time shift for production · peak load shaving for distribution · smoothen load for average energy · backup power or black out start · grid support

Energy Production

Charging

Discharging

Average Power kW

t
Process Power Grid Power Charging Discharging

Average Power t
Figure 1. Power balancing

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASICS

vacon · 3

1.1

Power or energy storage

It is important to distinguish the system's "nature", that is, whether it is a power application or an energy application. Another relevant thing to note is the dynamic requirements of the application.
Determining the application:
· Energy vs. power (kW/kWh ratio) · Dynamic requirements:
o Grid support functions (Harmonics, FRT) o Bulk energy time shift

Power Applications

Power: Energy MW: MWh

Energy Applications

4:1 3:1 2:1 1:1 1:2 1:3 1:4

Power [MW] Power [MW] Power [MW]

4:1 Time [h]

1:1 Time [h]

Figure 2. Power vs. energy

1:4 Time [h]

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
1

vacon · 4

BASICS

Energy density in Wh/kg

1,000
100 10 1 0.1
0.01 10

BC DE

10,000s

1,000s

100s

10s

1s F 0.1s
G

100

1,000

Power density in W/kg

10.000

Reference

Batteries

Li-ion

Double layer capacitors

NiCd

Electrolytic capacitors

NiMH

Figure 3. Comparision of battery systems

Battery type
Lead acid battery Nickel-metal hybride
battery Lithium-ion battery Spercaps (double
layer capac.)

Table 1. Comparision of battery systems

Energy density Wh/kg

Power density W/kg

30-50

150-300

Service life in cycles/years
300-1,000/3-5

60-80

200-300

>1,000/>5

90-150

500 -> 2,000

>2,000/5-10

3-5

2,000-10,000

1,000,000/unlimited

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASICS
© Electricity storage association Discharge Time [hr] 100

10 VR
Li-ion

Na-S

CAES

Zn-Br

L/A

Ni-MH 0.1

Ni-CD

0.01

Na-S

0.001

EDLC

vacon · 5 PHS

0.0001 0.001

0.01

0.1

Rated Power [MW]

100 1000 10,000

#
A B C CAES EDLC FW L/A Li-ion Na-S

Reference
Energy management Bridging power Power quality Compressed air
Dbl-layer capacitors Flywheels Lead-acid Lithium-ion
Sodium-sulfur

#
Ni-Cd Ni-MH PSH
VR Zn-Br

Figure 4. System ratings

Reference
Dicharge time
Nickel-cadmium Nickel-metal hybride
Pumped hydro Vanadium redox
Zinc-bromine

1.2

Battery current dimensioning

In a battery, the nominal current is denoted with C. For example, a 10Ah 1C current would be 10A. In some cases, the below rated currents are marked as 0.5C = C5. In that case, for example a 10Ah rated current used with a 1A current would mean 0.1C or C1. In the same example, 2C would mean 20A.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
1

vacon · 6

BASIC TOPOLOGIES FOR CONNECTION

2. BASIC TOPOLOGIES FOR CONNECTION

The basic connections are divided into multible possibilities.

Use case

Table 2. Basic connections

Topology

Pros

Common DC energy storage connection

Filter

· No competitive "technology" when DC-grid connection needed
· Different storage voltage/technology adaptations

Cons

Energy storage to ACgrid with combination of DC/DC converter + grid converter

Filter Filter

· Different storage voltage/technology adaptations
· Expansion easy · Battery stack
replacing due to ageing

· Large number of components
· Lack of efficiency · Size

Energy storage directly to AC-grid with grid converter

Filter

· Small number of components
· Efficiency · Size · Power vs. energy
dimensioning is independent from each other

· Expansion difficult · Battery stack
replacing due to ageing

Energy storage close to load and AC-grid with DC/DC converter connected between DC-link and storage

Filter Filter

· Load power/ energy support close the consumption
· Different storage voltage/technology adaptations
· Expansion easy · Battery stack
replacing due to ageing

· Large number of components
· Size

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC TOPOLOGIES FOR CONNECTION

Energy storage close to load and AC-grid with direct DC-link connection

Filter

vacon · 7

· Load power/ energy support close the consumption
· Large number of components
· Efficiency · Size · Power vs. energy
dimensioning is independent from each other

· Voltage window limiting the scope only in range of 400 Vac using DC range 600-1100 Vdc
· System expansion later with additional batteries difficult

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
2

vacon · 8

SPECIAL CHARACTERISTICS AFFECTING THE

3. SPECIAL CHARACTERISTICS AFFECTING THE SELECTION

Different chemistry causes different behavior in cell voltage as a function of charge/discharge and SOC (State of Charge). This creates "voltage window" requirement similar to the solar inverter.
Galvanic isolation requirement is different from many industrial drive application. This is due to the fact that the battery system should not be predisposed for common mode voltage.
For the Battery Management System (BMS) to be able to reset the SOC calculation, it is necessary to charge the battery to 100% SOC. This ensures that BMS is able to calculate SOC accurately and maintain the battery in safe operating area. For this, a balance charger or a maintenance charger is needed in some cases.

3.1

Voltage window

For both the DC/DC converter and the GTC (Grid Tie Converter) the first dimensioning question comes from energy storage (battery) voltage dimensioning. It is important to define the "voltage window" for empty and full battery cell voltage. Depending on battery chemistry the ratio can be full/ empty = 1,2... 2... (meaning, for example, full being 1000 Vdc, and empty being from 800 Vdc to 500 Vdc) and for super capacitors even bigger. Especially for GTC this is a limiting factor. The limitations come from minimum tolerable DC-link voltage to maintain controllable grid voltage and from maximum allowed voltage to maintain within design criterion of the hardware.
The behavior of voltage stretch in a battery can be illustrated with a spring being pulled or pushed.

UDC [%] 120

100

Discharging of battery Charging of battery

80 100

SOC [%]

Figure 5. Spring analogy of the battery voltage change

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

Discharging of battery Charging of battery

SPECIAL CHARACTERISTICS AFFECTING THE SELECTION
UDC [%] 120
100

vacon · 9

80 100

SOC [%]

Figure 6. Battery voltage change as a function of State Of Charge (SOC)

The voltage window is important also from the process dynamics point of view. If we expect the battery system to take energy (either discharge or charge), we create change in voltage of the battery. The voltage controller needs to be capable to change the actual voltage of the battery in a controlled way from full to empty value or from empty to full value. For example, if the battery is wanted to be discharged in 30 s - 300V voltage window from 1000 Vdc - 700 Vdc it means roughly 10 V/s voltage change of rate. This is huge difference in comparison to for example case where discharge time is longer, say 30 min resulting in 0,2 V/s. This way the SOC (State of Charge) behavior is observed.
Below is a case where same sized of DC-power units are charged/discharged from the battery.

Figure 7. Battery string number effect on voltage change using the spring analogy
24-hour support +358 (0)201 212 575 · Email: service@vacon.com
3

vacon · 10

SPECIAL CHARACTERISTICS AFFECTING THE

The difference in the cases is that the battery size in energy is changed from 6 strings in parallel to one string in parallel. This will lead in higher C-rates in the battery having smaller amount of strings when the same amount of power is taken out of each battery setup (current going from 1C --> 6C). The effect is visible in higher stretch of voltage levels needed in controlling the battery.

123456

12345

Figure 8. Number of batteries

UDC [%] 120

100

t 80

I [C-rating] 8
6

increasing load current

0 -2

-4

-6 t-8 increasing charge current t

0.2 0.25
0.2 0.35
0.4 0.6 0.65 0.7 0.75 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
1

Figure 9. Battery sizing effect on voltage change during equal power changes
The spring analogy works also when thinking of parallelizing of batteries (springs). The more you have batteries (springs) in parallel, the less you need to use voltage stretch to gain the same response.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

SPECIAL CHARACTERISTICS AFFECTING THE SELECTION

vacon · 11

3.2

Galvanic isolation requirement

The pulse width modulation (PWM) produces common mode voltage. Because every phase (a, b and c) can be connected only either to positive DC-bus (+Udc/2) or to negative DC-bus (-Udc/2), sum of output voltages is always unequal to zero. The common mode voltage (CM-voltage) Ucm can be calculated as average of output voltages:

Table 3 presents all possible common mode voltages produced by different switching states. Used reference point is in the middle of the DC-link.

Table 3. Common mode voltage as function of modulation sequence

Switching vector a

Ucm

-Udc /6

Udc /6

-Udc /6

Udc /6

-Udc /6

Udc /6

Udc /2

-Udc /2

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
3

vacon · 12

SPECIAL CHARACTERISTICS AFFECTING THE

U [V] 600
400

CM voltage

Common mode

200

-200

-400

-600 40

40.10 40.20 40.30 40.40 40.50 40.60 40.70 40.80 40.90 41

UDC/6

UDC/2

CM voltage

Time [ms]

Curve info

......

UDC/2

----

UDC/6

___

CM voltage

max

min

rms

171

512

-512

264

Figure 10. Simulated CM-voltage, Udc=1025V, fsw=5kHz.

Because of the common mode DC-link starts to jump compared to ground. Main frequency for this jumping is switching frequency but also higher frequencies will be present. As an example, a typical measured DC+ to ground voltage can be seen in Figure 11. A rule of thumb is that with a typical DClink voltage 1025V, the voltage spikes will be about 1.5kV.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

SPECIAL CHARACTERISTICS AFFECTING THE SELECTION

vacon · 13

voltage [V] Sampled waveform 1500 1000
500 0
-500 -1000

voltage [V]
1200 1000
800 600 400 200
0 -200 -400 -600

Sampled waveform

0 0.005
0.01 0.015
0.02 0.025
0.03 0.035
0.04 0
0.005 0.01
0.015 0.02
0.025 0.03
0.035 0.04

time [s]

Figure 11. DC+ to ground voltage. On the left Udc = 1200 V, on the right 800 V.
The battery system does not withstand unfiltered common mode voltage. Because PWM modulation is a CM voltage source, the DC side of the energy storage system must be stabilized. This means that there must be a flexible element in electrical system that is able to take this common mode voltage fluctuation. This element is now a transformer star point (instead of a motor stator star point) that shall not be grounded.

DC-link

AFE (Active Front End)

LCL-filter

Transformer

CM
Figure 12. Transformer must be isolated from ground. In the grid side filter, if LCL is used, the grounded capacitors cannot be kept connected to ground. If transformer inductance is bigger or at least the same as proposed grid side inductance, it is possible to use only an LC filter (sine) to avoid additional voltage drop in the grid side choke.
24-hour support +358 (0)201 212 575 · Email: service@vacon.com
3

vacon · 14

SPECIAL CHARACTERISTICS AFFECTING THE

HF no HF

-L1 U2

-R1

-R4

-C1.1 -C1.2 -C4.1-C4.2

-R2

-R5

-C2.1 -C2.2 -C5.1-C5.2

-R3

-R6

-C3.1 -C3.2 -C6.1-C6.2

-L2.1

-L2.2

-L2.3

-C1 -C3
-C2

Figure 13. LCL ground capacitor must be disconnected

3.3

Balance or maintenance charge

The maximum voltage of the battery is needed only when charging the battery at the fullest level. Current in that voltage is small. However, the time during which this voltage prevails can be theoretically infinite if the battery is continuously kept 100% full (which is not advisable because of the aging of the battery). When the charging is finished and even only little load is given to the battery, the voltage decreases rapidly.
It is necessary (after a certain time or a number of battery charge/discharge cycles) to "reset the trip meter" of the Battery Management System. Otherwise the state of charge calculations can become misleading and result in poor behavior or even in exceeding the safe operation limits. The only good way to "reset the trip meter" is to charge the battery to the full state where the Battery Management System can safely tune its SOC value back to 100%.
Every cell must be charged extremely slowly so that the current of each cell goes as low as possible (the cell reaches its full voltage). For a big battery system that has many cells in parallel and in serial this is done from the same DC+ and DC- connections with the same Udc control. Do not start to dismantle batteries to charge them individually. Because of the differences in cell level (for example SOC, impedance) this means that some of the cells fill up sooner than others.
To avoid overcharging, the natural passive balancing of the battery system is needed. However, this is a slow process and that is why the balancing charge needs to be slow with an accurately controlled small current. It is difficult to say how accurate and small the current needs to be, but the rule of thumb is that 0.01C is needed. If the device is not able to provide accurately such a current, it is necessary to add a balance charger to the system. The battery manufacturer can also be consulted about balance chargers.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

Discharging of battery Charging of battery

SPECIAL CHARACTERISTICS AFFECTING THE SELECTION
UDC [%] 120
100

vacon · 15 A

SOC [%]

80 100

Reference

Not possible to reach 100%

Not safe to go empty SOC

A SOC with big current = B with big current. BMS to tell

Balance charger?

when stop discharging.

Figure 14. The need of a balance charger

A balance charger is basically the same as a bulk power device (grid converter or DC/DC converter) but with a smaller rating to be able to reach a control accuracy of storage current of 0.01C.

3.4

System control principles

The energy storage systems are often incorporated with different layers of controls having different responsibilities.
The Energy Management System optimizes the energy efficiency of the system. This can include choosing and prioritization the usage of different energy sources. Normal time scales are from tens of seconds to hours.
The Power Management System includes controlling of power balance in a system that has multiple energy/power sources. Normal time scales are from grid cycle (20ms - 50Hz) to seconds.
The Power Conversion System of this list is the system relevant to the product. The PCS includes Power Conversion Control and Power Conversion Hardware, which is the VACON® hardware. It is to control power conversion between the energy storage and the system. Normal time scales are from micro seconds to grid cycles.
The Storage System includes Battery Management System and the battery. Battery Management System monitors the storage system as well as the storage cell level phenomena.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
3

vacon · 16

SPECIAL CHARACTERISTICS AFFECTING THE

Energy Management System (EMS)

Power Management System (PMS)

Power Conversion System

Storage System

Power Conversion Control (PCC)

Battery Management System

Power Conversion Hardware

Battery

Figure 15. Typical system layers

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

CHOOSING A CORRECT TOPOLOGY
4. CHOOSING A CORRECT TOPOLOGY

vacon · 17

Grid

Converter needed in all cases

Connection to

AC or DC

For example

VACON®

small

Voltage window

large

Common DC-buss

Direct to DC

DC/DC converter

Filter Filter

Filter

Application
Customer system tailoring

Grid Converter needed in all cases

Island

AFE

uGrid

Control modes

Control ref P / Udc /Idc

Customer primary reference

Figure 16. Selection diagram

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
4

vacon · 18

CHOOSING A CORRECT TOPOLOGY

4.1

Allowed topology configurations

In the following table, example of allowed and not allowed configurations are given.
These configurations are valid for both with DC/DC converter or with a direct battery connection into the DC-link. Options shown below are DC/DC configurations A), B) and C) and Direct to DC connection D). Note that the storage topology does not affect the allowed or not allowed topology of the connection to the system. There might however be other limitations, for example voltage or current ratings.

OK?
4

Figure 17. Options A, B, C, D
Table 4.
Configuration

Options

A, B, C, D

Notes
No grounding allowed in transformer

Options A, B, C, D

Options

A, B, C, D

Options

A, B, C, D

No HF/EMC capacitors in LCL
OK
OK, transformer has enough inductance to satisfy filtering demand of grid converter: Ltransformer ~ Lgrid side choke

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

CHOOSING A CORRECT TOPOLOGY

Options

A, B, C, D

Options

A, B, C, D

Options

A, B, C, D

Options

A, B, C, D

Options A, B, C, D
Options A, B, C, D

vacon · 19
NOT OK Separate DC sources create different output voltage pattern which creates circulating current
Not OK if grid selectivity is needed, specially for uGrid
Not OK if grid selectivity is needed, specially for uGrid

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
4

vacon · 19

5. BASIC VARIANTS

5.1

Direct to DC

AFE DC

INU AC

Grid converter

AFE AC

u INU

u AFE
Filter

BASIC VARIANTS
Grid AC
u GRID

A B

Rectifying DC/AC and AFE control
marginal

Filter voltage
drop

Transformer voltage ratio
and drop

Grid nominal value and voltage tolerances

80 100

SOC/%

1C 2C
3C 6C 9C

+ Tolerance 1 pu - Tolerance

Supply voltage max Supply voltage min Over voltage instantly Over voltage U2t trip DC high ready (Stop) Normal Max Normal Min DC low run (Def.estim.) DC low ready (Stop) DC low running min Under voltage instantly

Reference

Maximum tolerable UDC voltage for AFE operation

230 V Unit 500 V Unit 690 V Unit Vac

240

500

690

Vac

208

380

Vac

437

911

1200

Vdc

1100

Vdc

382

797

1099

Vdc

324

675

931

Vdc

280

513

708

Vdc

242

475

656

Vdc

239

436

602

Vdc

225

410

567

Vdc

183

333

461

Vdc

Reference

Minimum tolerable UDC voltage for AFE to
stay in grid with cos=1

Figure 18. Direct to DC

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS
5.1.1 Control structure The power control is as presented below when the battery is directly on DC-link.

vacon · 20

Grid

Source DC
C

U3 Filter U4

Q1 Q3

Figure 19. DC-link power control
Direct to DC can be used on a system where peak power shaving is desired and grid power sources' power sharing is done mainly through active power drooping. In such system, the power and grid frequency behave as shown in the picture below.

Generator Motoring

Charge Discharge

Average

Power

Frequency

Figure 20. Behavior of system power and grid frequency
Grid Converter operation:
· uGrid-operation mode o Power control possible when operating parallel with other power sources. ·Reference is base current reference (+/-). ·If the device is operating in island mode, the power reference changes the frequency. o Grid frequency variations will affect what will be actual power to the grid. ·Operates like a normal generator. ·Power reference is several times faster than a normal diesel generator. ·Frequency drop in a grid will increase Grid Converter power output without power reference. - Useful in situations where PMS is not fast enough or is unable to control. o Upper system needs to give charging and discharging limit to the drive o Upper system needs to give minimum and maximum voltage limits to the drive (DC-Link voltage).

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 21

BASIC VARIANTS

· AFE-operation mode o Power control possible trough DC voltage reference. Needs controller if customer input is power reference (instead of DC voltage reference). o Cannot make or maintain grid by itself, needs existing grid
· Island-operation mode o Power control not possible, drive will give to the grid what the grid needs. o Cannot operate parallel with other power sources. o Makes a grid but cannot synchronize to the existing one.
When doing maintenance charging with the aim of a 100% full battery, charging must be done with DC reference (possibly with a charging current limit).

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

5.2

DC to DC

Battery DC

L L L

vacon · 22

AFE DC

INU AC

Grid converter

AFE AC

u INU

u AFE
Filter

Rectifying DC/AC and AFE control
marginal

Filter voltage
drop

B
0

80 100

SOC/%

Reference

Maximum full battery UBattery voltage for fixed AFE reference voltage operation

Reference

Minimum tolerable UBattery voltage for DC/DC & filter current ripple

Figure 21. DC to DC

5.2.1 Filter

The filter topologies in focus are: 1. Interleaved

HF HF
Figure 22. Interleaved filter topology

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 23
2. Independent output control (not yet supported)

BASIC VARIANTS
HF HF

Figure 23. Independent output control
Interleaving is a method to cancel partially or completely certain harmonics from the spectrum. With a standard 3-phase inverter unit, a natural way is to have a 120 degree phase shift with each triangle carrier. The result is that the maximum peak to peak ripple is reduced to one third of the individual phase current ripple. Thus, while the sum current is multiplied by factor of three, the maximum relative output current ripple is reduced to 1/9. The equivalent switching frequency in the output is three times the switching frequency.

I [A] 350

Currents

Interleaved

300

250

200

150

100

50 40

40.10 40.20 40.30 40.40 40.50 40.60 40.70 40.80 40.90 41

Time [ms]

I Battery

Curve info
I 1 I 2 I 3 I Battery

rms
100.3 100.3 100.3 300.0

max
113.0 113.0 113.0 304.6

min
87.0 87.0 87.0 295.4

peak to peak
25.9 25.9 25.9 9.1

Figure 24. Example simulation with interleaved control and d = 1/2: leg currents and sum current. I = 100 A/leg, L = 2050 uH, Udc = 1025V

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

vacon · 24

I [A] 350

Currents

Interleaved

300

250

200

150

100

50 40

40.10 40.20 40.30 40.40 40.50 40.60 40.70 40.80 40.90 41

I Battery

I1=I2=I3 Traditional

Time [ms]

Curve info
I 1 I 2 I 3 I Battery

rms
100.2 100.2 100.2 300.7

max
112.6 112.6 112.6 337.9

min
87.4 87.4 87.4 262.1

pk2pk
25.2 25.2 25.2 75.7

Figure 25. Example simulation with traditional control and d=1/2: leg currents and sum current. I = 100A/leg, L= 2050 uH, Udc = 1025V

The ripple current for the filter choke can be calculated as follows:

It is important to note that the ripple depends on duty cycle which is defined as follows:

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 25
The maximum value for the ripple of the choke is obtained when d = 1/2

BASIC VARIANTS

For the output current ripple there are three segments. When d < 1/3, two switches are always at low state and one switch is either low or high. When 1/3 < d < 2/3, one switch is low, one high and one is either low or high. And when d > 2/3, two switches are always high and one either low or high. With d = 1/3 and d = 2/3, output ripple is in theory cancelled. In practice simultaneous switching prohibit causes some ripple. Disabling simultaneous switching prohibit logic will reduce fluctuation near d = 2/3 and d = 1/3 considerably.

The maximum value is obtained with three different duty cycles:

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

vacon · 26

Ripple current: Choke IL,pp (blue) / Output IOut,pp (black) 0.25
0.2
0.15
0.1
0.05
0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Duty cycle
Figure 26. Peak-to-peak ripple current as function of duty cycle. Scaled values can be converted to real values by multiplying Udc/(fsw*L)
Interleaved switching helps to reduce the output ripple, but does not affect the single choke ripple. The choke losses are thus relatively big, when compared to e.g. active front end (AFE). To keep the losses reasonable, it is recommended to have peak-to-peak ripple one fourth of the nominal choke current. Thus the proposed formula to calculate the required inductance is:

Using the above filter dimensioning, the relative output ripple is:
Example with a ~ 3% peak-to-peak: The ripple current is a triangle wave and the RMS value is peakto-peak divided by 2 3 , i.e. 0,8% RMS. A more general formula for inductance calculation is:

This can be used for example with powder core chokes which tolerate more ripple. With liquid cooling peak-to-peak ripple can be approximately 35-45% of the nominal current. A bigger ripple in the choke also directly increases the output side ripple which in this case would be approximately 4-5% peak-to-peak.
24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 27

BASIC VARIANTS

In most cases, a duty cycle d = 0,5 should be used in calculations. This will guarantee that worst case ripple is taken into consideration. For example, if the application operates with duty cycles 0.7-0.9, it could be possible to decrease the inductance, and in that way increase the choke ripple (see Figure 27 below). However, this would also increase the output ripple, and it might not be acceptable. On the other hand, if output ripple is not important, duty cycle optimization can lead to significant savings.

Ripple current: Choke IL,pp (blue) / Output IOut,pp (black) 0.25

0.2

0.15

0.1

0.05

0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Duty cycle
Figure 27. Always consider possible duty cycle window
A big DC-link voltage requires more inductance. If the DC/DC converter is sometimes used to boost DC-link higher than nominal, it must be noted that ripple increases.
In order to minimize size (inductance) of the filter choke switching frequency and current, ripple should be as high as possible. An optimal design is a compromise between these and power losses. When the design is ready, switching frequency decrease is not allowed, otherwise ripple will increase and this can cause temperature problems. In an LCL-filter structure, a smaller switching frequency can also cause resonances.
The inductance of a traditional laminated iron core choke usually remains constant (LNOM) up to saturation point (INOM, PEAK in Figure 28 below). After saturation point, the inductance starts to decrease. If overload ability is needed, ripple increases in saturation region and must be considered in the design. The inductance of a powder core choke behaves differently. Usually inductance as a function of current decreases continuously which means that with small currents the inductance is bigger. This is an advantage because ripple with partial loads will be smaller. On the other hand, it must be verified that the core is not going to saturation too fast, if overload ability is needed. How big the initial inductance is depends on choke design but typical values range approximately from 20% to 50% over nominal.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS L [H]

vacon · 28

LNOM LSAT

Powder 1 Powder 2 Laminated iron

INOM, RMS INOM, PEAK LMAX, PEAK

I [A]

Figure 28. Inductance as function of current (relative values).
The typical tolerance for inductance is ±10%. Also smaller tolerance can be achieved, if needed. In the DC/DC converter, inductance tolerance does not affect the current balance between legs like in standard AC applications. Because of tolerance, switching frequency is not totally eliminated from the output current. This will increase the ripple and can cause some resonance issues with optional filtering capacitors. Tolerances also increase/decrease individual peak-to-peak ripple currents of chokes (Figure 29 and Figure 30). Temperature tolerances are not typically a concern with the above mentioned choke types if all chokes are of the same temperature.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 29

BASIC VARIANTS

I [A] 350

Currents

Interleaved

300

250

200

150

100

50 40 40.10
I Battery

40.20 40.30 40.40 I1

40.50 40.60 I2

40.70 40.80 I3

40.90 41 Time [ms]

Curve info
I 1 I 2 I 3 I Batteri

rms
100.4 100.3 100.3 300.0

max
116.0 113.0 113.0 307.6

min
83.9 87.0 87.0 292.4

peak to peak
32.1 26.0 26.0 15.2

Figure 29. Example simulation with interleaved control and d = 1/2: leg currents and sum current. I = 100 A/leg, L = 2050 uH, Udc = 1025V. Leg U has 20% less inductance.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

vacon · 30

I [A] 350

Currents

Interleaved

300

250

200

150

100

50 40 40.10
I Battery

40.20 40.30 40.40 I1

40.50 40.60 I2

40.70 40.80 I3

40.90 41 Time [ms]

Curve info
I 1 I 2 I 3 I Battery

rms
100.4 100.3 100.2 300.0

max
116.0 113.0 110.9 308.4

min
84.0 87.0 89.1 291.6

peak to peak
32.0 25.9 21.8 16.9

Figure 30. Example simulation with interleaved control and d = 1/2: leg currents and sum current. I = 100 A/leg, L = 2050 uH, Udc = 1025V. Leg U has 20% less and leg W 20% more inductance.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 31

BASIC VARIANTS

The filter consists of three separate chokes, one for each leg (Figure 31). It is not possible to use a traditional 3-phase choke because the current is DC (common mode) and the magnetic flux does not have a natural return path in the core structure. There would be only a very small inductance generated by stray flux and this kind of situation can lead to a burnt filter. That is why a 3 x 1-phase structure is necessary. In addition, the stray capacitance should be small. Foil winding with many overlapping turns is not recommended. One way to minimize the stray capacitance is to use wire winding in one layer.

DC+

CDC DC-

L1 Battery

Figure 31. Simple filter consist of three separate chokes.
The target is that the filtering could be done with chokes only. That is a simple solution, and one benefit of not having capacitors is that switching the battery/supercapacitor is possible without any current spikes. When IGBTs are disabled, the connection requires only that the DC-link is higher or equal. If the output current ripple requirement is low and the required inductance would lead to an impractical design, one possibility is to use an optional filtering capacitor (Figure 32). The best case would be to add one more choke to form an LCL-filter structure (Figure 33). Without interleaving, an LCL-filter is recommended, otherwise ripple will be big (nine times bigger).

DC+ CDC DC-

L1 Battery
Figure 32. Optional capacitor (C) connected to filter output.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

vacon · 32

DC+ CDC DC-

L1 L2

Battery

Figure 33. LCL-filter structure is best possible solution if output ripple is critical.
The optional capacitor forms an LCL-circuit with the cables and the battery. It is important to know the cable/battery impedance/inductance in order to evaluate possible resonances and calculate a safe capacitance value. The impedance of the battery seems to depend on many things so this is not an easy task. The resonance frequency for the LCL-circuit can be calculated as:

Note that the inductance of the converter side choke is one third because of the parallel connection. In addition, there can be resonance can happen between L1 and C or L2 and C:
All these resonance frequencies must be well below the switching frequency. In standard inverter applications, the LCL-circuit resonance frequency is usually one third of the switching frequency. Because equivalent switching frequency at output is three times bigger, in theory it would be possible to use higher resonance frequencies. But as explained earlier, the switching frequency is not totally eliminated at output because of non-idealities in the control and chokes. Because battery properties are usually not well known, it is recommended to dimension the optional capacitor as follows:

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 33

BASIC VARIANTS

This will give some idea what could be expected to work, but because the battery properties are not taken into account in the design, it is not possible to guarantee a safe operation. If the filter does not operate as expected, the capacitance value can be increased for example by adding another capacitor in parallel. Without interleaving, the capacitor must be a lot bigger (for example ten times bigger) if the target is to be in the same level as with the interleaving control and chokes only. Note, however, that this especially depends a lot on the battery.
With a real LCL-filter structure, dependence of the battery properties is minimized and the design is more robust against resonances. The requirements for an additional battery side choke are quite simple because the ripple is very small. The voltage rating of the filter capacitor should be similar to the DC/DC converter DC-link capacitors.
The proposed rule to dimension an LCL filter is based on a safe resonance frequency. In this case it is estimated that half of the switching frequency would be small enough with interleaving. In addition, the battery side choke L2 is determined as 1/6 of L1 which corresponds to the typical inductance ratio of chokes in standard inverter applications. With these assumptions, the required capacitance (minimum value) can be calculated as:

Without testing, the interleaving capacitor must be bigger. At least double the size is recommended.
Crucial tests to verify filter applicability are:
1. Thermal tests: The worst case scenario for the filter in a thermal point of view is an operation point where continuous current is maximum, DC-link voltage as high as possible and duty cycle d = 1/2. At this point current ripple is the biggest.
2. Current tests: The worst operation point for current (both choke and output) is same as in the thermal tests. With interleaving, the output performance can be verified also with other peak and valley points of the duty cycle curve. If a capacitor is used, also the capacitor current should be measured.
3. Voltage tests: The voltage at the battery terminals should be measured. If the cable to the battery is long, the voltage at the filter output can also be measured. The voltage against ground is also interesting.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

BASIC VARIANTS

vacon · 34

5.2.2 Control Structure
The figure below presents power control when the DC/DC converter is between DC-Link and the battery.

Grid

Source DC
C

DC/DC

Converter

L L

DC-Link

U3 Filter U2

Figure 34. Power control example
DC to DC can be used on a system where peak power shaving is desired, and grid power sources' power sharing is done mainly through active power drooping. In such system, the power and grid frequency behave as shown in the picture below (Figure 35).

Generator Motoring

Charge Discharge

Average

Power

Frequency

Figure 35. Behavior of system power and grid frequency
Grid Converter operation.
· Power control possible when operating parallel with other power sources. o Reference is base current reference (+/-). o If the device is operating in island mode, the power reference changes the frequency.
· Grid frequency variations will affect what will be actual power to the grid. o Operates like a normal generator. o Power reference is several times faster than a normal diesel generator. o Frequency drop in a grid will increase grid converter power output without power reference. ·Useful in situations here PMS is not fast enough or is unable to control. ·Upper system needs to give charging and discharging limit to the DC/DC converter.
· Upper system needs to give minimum and maximum voltage limits to the DC/DC converter. o Grid Converter needs also under voltage limit because battery voltage can come directly to DC-Link trough DC/DC converter, if DC-Link voltage goes below battery voltage.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
5

vacon · 35

BASIC VARIANTS

· Charging can be achieved by upper system control or simply by Value ID Control functions. Charging will start automatically when the DC/DC converter overvoltage limit is reached even without charging reference.
· When the grid converter power flow is parallel to the grid, the DC-Link voltage will go down until it reaches the DC/DC converter undervoltage level, where the voltage remains until the DC/DC converter discharging current limit is reached.

uG OV Level DC OV Level
DC UV Level uG UV Level

Current limit charging Controlled charging possible
Discharging

Figure 36. Charging and discharging
· AFE-operation mode. o Not practical. Could be possible when DC/DC operated with under voltage control with a drooping. But DC reference changes makes steep power changes.
· Island-operation mode o Power control not possible, drive will give to the grid what the grid needs. o Cannot operate parallel with other power sources. o Makes a grid but cannot synchronize to an existing one.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

PRODUCT CONFIGURATION EXAMPLES

vacon · 36

6. PRODUCT CONFIGURATION EXAMPLES

6.1

Scope of delivery

VACON delivers energy storage related power conversion equipment. The DC/DC converter includes power conversion hardware and power conversion control related software.
VACON does not deliver energy management systems, power management systems, or battery management systems.

Energy Management System (EMS)

Power Management System (PMS)

Power Conversion System

Storage System

Power Conversion Control (PCC)

Battery Management System

Power Conversion Hardware

Battery

Figure 37. Vacon offering considering system level.
6.1.1 Direct to DC
The scope of delivery of VACON includes the typical VACON offering from power modules to system drive or other suitable switchgear. The simplest delivery includes power modules, LCL filters, NXP controls with an application and a license. All the rest is handled by the system integrator. NOTE! The selection of available power modules can be seen in a separate chart.
24-hour support +358 (0)201 212 575 · Email: service@vacon.com
6

vacon · 37

PRODUCT CONFIGURATION EXAMPLES

The line measurement board D7 is instructed to be included in the delivery.

Danfoss

NXP/NXI HW Application SW License

HF
no HF

-L1 U2

-R1

-R4

-C1.1 -C1.2 -C4.1-C4.2

-R2

-R5

-C2.1 -C2.2 -C5.1-C5.2

-R3

-R6

-C3.1 -C3.2 -C6.1-C6.2

-L2.1

-L2.2

-L2.3

LCL or

-C1

Sine Filter

-C3

-C2

Customer/ Danfoss

Figure 38. Scope of delivery
In tailored customer projects, the scope of delivery may be a switchgear including power modules, LCLs, NXP controls with an application and a license, but also breakers, fuses, DC pre-charging components and other possible control circuit.

Figure 39. Scope of delivery
6.1.2 DC to DC
The scope of delivery of VACON includes the typical VACON offering from power modules to system drive or other suitable switchgear. The simplest delivery includes power modules, NXP controls with an application and a license. Deliveries of single phase chokes are not preferred to be handled by VACON as the dimensioning varies case by case. Still, delivery of chokes is negotiable. All the rest is handled by the system integrator. NOTE! The selection of available power modules can be seen in a separate chart.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

PRODUCT CONFIGURATION EXAMPLES

vacon · 38

Danfoss

Customer/ Danfoss

NXP/NXI HW Application SW License
Filter Single Phase Choke
Figure 40. Scope of delivery In tailored customer projects, the scope of delivery may be a switchgear including power modules, chokes, NXP controls with an application and a license but also breakers, fuses, DC pre-charging components and other possible control circuit.

Figure 41. Scope of delivery
24-hour support +358 (0)201 212 575 · Email: service@vacon.com
6

vacon · 39

PRODUCT CONFIGURATION EXAMPLES

6.2

Example configurations

6.2.1 DC/DC for supply interruptions
The DC/DC converter can be used to prevent grid voltage drops to interrupt essential drives to stop for undervoltage. The DC/DC converter is connected to the AC drive's DC-terminals and used to feed power during the grid voltage drops. Essential motors can run and ride through the voltage drops without interruption.
SUPPLY
-F1

-L1 L
-F2 -U1 NXP
-U2 DC/DC

-M1 3

-L2 L -B1

Figure 42. Failure ride through with undervoltage control
The DC/DC converter can be used to support the grid by equalizing the power peaks and producing the power if the main grid voltage drops. The DC/DC converter is connected to the grid converter and power can run in both directions by charging and discharging the batteries.

SUPPLY

Q0 M

-F1
-L1 LCL -U1 NXA -F2 -U2 DC/DC -L2 L
-B1
Figure 43. Peak shaving of AC-grid

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

PRODUCT CONFIGURATION EXAMPLES

vacon · 40

6.2.2 Direct DC for Grid Support
In case the battery voltage window is favorable, the batteries can be connected directly into the DC. The same usage case of power balancing of the grid also applies here. In below an example of case where connection to the grid transformer is 440Vac and the battery voltage window is set to be 7501100Vdc.

INCOMING 3PH, AC SUPPLY

QA1 2000A, 3P, LSI, 65kA
MAIN BREAKER

3
I> I>>

QA1 2000A, 3P, LSI, 65kA
MAIN BREAKER

3
I> I>>

-FC1.1-FC1.3 3 -FC1.1-FC1.3 3

-RF4 3

1030A

LCL FILTER

-FC1.1-FC1.3 3 -FC1.1-FC1.3 3

-RF4 3

1030A

LCL FILTER

-TB1 3 NXA10306
AFE UNIT

-FC2 2

-FC2

OEVA

SWITCH

2 SWITCH

-TB1 3 NXA10306
AFE UNIT

-FC2 OEVA SWITCH

-FC2 2

OEVA

2 SWITCH 2

OUTGOING DC SUPPLY Figure 44. Peak shaving of higher power and high energy AC grid

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
6

vacon · 41

SIZING OF THE SYSTEM AND PRODUCT

7. SIZING OF THE SYSTEM AND PRODUCT

The basic principles that have an effect on the power unit selection are described in this chapter.

7.1

Direct to DC

The energy storage voltage window sets up the guideline for the voltage class selection. The maximum voltage sets the requirement for using either 500 V class or 690 V class units. The value of DC High Ready (Stop) should be taken into account when choosing the appropriate unit with adequate maximum voltage. If the storage maximum voltage stays below 800 Vdc, it is possible to use 500 V class units. If it goes above 800 Vdc but stays below 1100 Vdc, the 690 V unit is applicable. NX8 voltage class liquid cooled units can be used up to 1200 Vdc link voltage.

Supply voltage max Supply voltage min Over voltage instantly Over voltage U2t trip DC High Ready (Stop) Normal Max Normal Min DC Low Run (Def.Estim.) DC Low Ready (Stop) DC Low Running Min Under voltage instantly

230 V Unit 240 208 437 382 324 280 242 239 225 183

500 V Unit 500 380 911 797 675 513 475 436 410 333

690 V Unit 690 525 1200 1100 1099 931 708 656 602 567 461

Vac/Vdc Vac Vac Vdc Vdc Vdc Vdc Vdc Vdc Vdc Vdc Vdc

The minimum voltage of the energy storage is crucial in current dimensioning of the unit size. An easy rule of thumb is that output voltage of grid converter is

The gain 1.56 is not accurate and depending for example on voltage drop in filters and grid state. Theoretically the gain can vary from 1.41 to 1.89. However 1.56 is a good starting point.
Now if the customer has indicated the needed power P, the corresponding current Iac for calculated voltage Uac can be calculated with:

The selection is made by choosing an appropriate current size from the VACON products with the above defined voltage class based on the maximum storage voltage level. The output voltage is needed for the transformer dimensioning.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

SIZING OF THE SYSTEM AND PRODUCT

vacon · 42

7.2

DC/DC

The current capability of the DC/DC converter is limited by two constraints. The first constraint is the current rating defined in the rating plate of the power converter that defines the operating area in which the CE and UL certification is valid.

DC+ I1
CDC DC- I4
I1

Battery

Figure 45. Vacon power converter ratings plate and their corresponding values in DC/DC converter circuit diagram.
The second constraint is the thermal limits of the power converter. There are two parts which are thermally stressed in the DC/DC application:
· The DC link busbars DC+ and DC- which are dimensioned according to I 1 of the DC/DC converter.
· The IGBT switches in the DC/DC converter due to high switching frequency.
There is a software current limiter in the DC/DC converter to ensure these constraints are not violated. The combined effect of the constraints thus becomes dependent on the voltage levels on the storage side and the converter DC-link according to the figure below. Formulas in the graph show how to calculate the output current I3 based on the current I1 which is denoted as INOM in the ratings tables of the DC/DC converter.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
7

vacon · 43

SIZING OF THE SYSTEM AND PRODUCT

IOUT / INOM 1.9

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

UBATTERY/UDC

Iout

Iout 1min

Figure 46. Current capability of a DC/DC converter
NOTE! INOM = I1~1.2*I2
An example curve in above shows the combined current limit line for the DC/DC converter depending on the ratio of storage voltage and converter DC-link voltage. The nominal current of a DC/DC converter is defined as I 1 in the DC/DC converter rating plate which is approximately 1.2*I 2 depending on the frame size. The value of IMAX and I1min vary depending on voltage class and switching frequency of the DC/DC converter. These values are higher when the switching frequency is decreased to 4 kHz and higher also for the NX5 voltage class units. In addition, the 1min limit applies only to frame sizes FI9-FI14.
NOTE! The nominal current of the DC/DC converter is not the same as the inverter current rating. You may roughly calculate the DC/DC converter current rating by multiplying the inverter current rating by 1.2. To have an overview, see the following table where the DC/DC converter current ratings for NX6 are given.

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
7

Air cooled NX6 drives

Unit type
NXI00106A0TOCSSA NXI00136A0TOCSSA NXI00186A0TOCSSA NXI00226A0TOCSSA NXI00276A0TOCSSA NXI00346A0TOCSSA NXI00416A0TOCSSA NXI00526A0TOCSSA NXI00626A0TOCSSA NXI00806A0TOCSSA NXI01006A0TOCSSA NXI01256AOTOISF NXI01446AOTOISF NXI01706AOTOISF NXI02086AOTOISF NXI02616AOTOISF NXI03256AOTOISF NXI03856AOTOISF NXI04166AOTOISF NXI04606AOTOISF NXI05026AOTOISF NXI05906AOTOISF NXI06506AOTOISF NXI07506AOTOISF NXI08206AOTOISF

Frame
FI6/IP21 FI6/IP21 FI6/IP21 FI6/IP21 FI6/IP21 FI6/IP21 FI7/IP21 FI7/IP21 FI8/IP100 FI8/IP100 FI8/IP100 FI9/IP100 FI9/IP100 FI9/IP100 FI9/IP100 FI10/IP100 FI10/IP100 FI10/IP100 FI10/IP100 FI12/IP100 FI12/IP100 FI12/IP100 FI12/IP100 FI12/IP100 FI12/IP100

Table 5. DC/DC converter current ratings for NX6

1025 VDC link voltage

1100 VDC

Inom

I1min

Imax

IDC nomi- PDC nom I1min

I1min

Iout

nal (A)

(KW) 5kHz (A) 3.6kHz (A) 5kHz (A) 3.6kHz (A)

11.1

14.6

18.3

14.6

23.7

20.3

26.3

32.9

108

143

117

119

122

167

146

149

188

250

183

228

168

172

216

288

210

263

198

203

255

340

231

309

245

251

312

416

231

309

308

315

392

522

382

477

383

393

488

650

450

594

454

465

578

770

450

600

490

503

624

832

450

600

548

562

690

920

673

841

598

613

753

1004

734

918

703

721

885

1180

863

1079

775

794

975

1300

870

1150

894

916

1125

1500

870

1150

977

1002

1230

1640

870

1150

1025 VDC

Imax

Iout

5kHz (A) 3.6kHz (A)

14.6

18.3

23.7

26.3

32.9

108

117

143

133

180

183

228

210

263

248

311

248

325

382

477

475

594

490

640

490

640

673

841

734

918

863

1079

951

1189

977

1200

977

1200

931 VDC

Imax

Iout

5kHz (A) 3.6kHz (A)

14.6

18.3

23.7

26.3

32.9

108

117

143

146

180

183

228

210

263

248

311

264

345

382

477

475

594

530

680

530

680

673

841

734

918

863

1079

1030

1189

1030

1300

1030

1300

vacon · 44

SIZING OF THE SYSTEM AND PRODUCT

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

Air cooled NX6 drives

Unit type
NXI09206AOTOISF NXI10306AOTOISF NXI11806AOTOISF NXI15006AOTOISF NXI19006AOTOISF NXI22506AOTOISF

Frame
FI13/IP100 FI13/IP100 FI13/IP100 FI14/IP100 FI14/IP100 FI14/IP100

1025 VDC link voltage

Inom

I1min

IDC nomi- PDC nom I1min

I1min

nal (A)

(KW) 5kHz (A) 3.6kHz (A)

1102

1130

1380

1840

1234

1265

1545

2060

1414

1449

1770

2360

1797

1842

2250

3000

2276

2333

2850

3800

2696

2763

3375

4500

1100 VDC

Imax

Iout

5kHz (A) 3.6kHz (A)

1275

1683

1275

1645

1275

1645

2196

2745

2568

3477

2568

3290

1025 VDC

Imax

Iout

5kHz (A) 3.6kHz (A)

1346

1683

1414

1780

1414

1780

2196

2745

2696

3477

2696

3474

931 VDC

Imax

Iout

5kHz (A) 3.6kHz (A)

1346

1683

1448

1884

1448

1884

2196

2745

2781

3477

2896

3733

SIZING OF THE SYSTEM AND PRODUCT

vacon · 45

SIZING OF THE SYSTEM AND PRODUCT

vacon · 46

A dedicated tool is available to help in the selection of a correct power unit based on either power or current profile. Examples of dimensioning based on storage power and current profiles are displayed in figures below.
The intermediate steps between INOM and IMAX can be calculated with the formulas given in the previous figure. The shape of the output current curve is due to the limitation of the I1 in the rating plate and the relation between input and output current of the DC/DC converter. The plateau part of the curve is due to thermal performance of the DC/DC converter. Current capability of the DC/DC converter may seem complicated but it simply yields a constant power capability up to the point IMAX where current cannot be increased anymore. The relation between current and power can be examined in the following graphs. Constant power is available as long as the voltage is sufficiently high.

Select:

Energy storage system parameters

Define Storage Power

Storage

Storage Storage

voltage

Power Current

range

Profile Profile

[Vdc]

[kW]

[Adc]

max voltage

700

350

500

nom voltage

375

300

800

min voltage

150

540

DC/DC Converter design parameters

DC-link voltage

750 Vdc

Class_5

DC-link power

343.0 kW

DC-link current

457 Adc dc-link

Storage output current

800 Adc storage

Power [kW] 450 400 350 300

Storage Power Profile

Storage Profile

NXI04605A0T0ISFA1A20000

NXI03855A0T0ISFA1A20000

smaller device @3.6kHz

100 200 300 400 500 600 700 800 900

Voltage [Vdc]

Power [kW] 1000
900 800 700

Storage Current Profile

Storage profile

NXI04605A0T0ISFA1A200000

200

0 NXI03855A0T0ISFA1A200000

100

smaller device @3.6kHz

100

200

300

400

500

600

700

800

900

Voltage [Vdc]

Figure 47. Power unit selection tool example based on storage current profile

Select:

Energy storage system parameters

Define Storage Current

Storage

Storage Storage

voltage

Current Power

range

Profile Profile

[Vdc]

[Adc]

[kW]

max voltage

700

335

235

nom voltage

375

400

150

min voltage

150

400

DC/DC Converter design parameters

DC-link voltage

750 Vdc

Class_5

DC-link power

229.8 kW

DC-link current

306 Adc dc-link

Storage output current

400 Adc storage

Power [kW] 300
250
200

Storage Power Profile

Storage Profile

NXI03005A0T0ISFA1A20000

NXI02615A0T0ISFA1A20000

smaller device @3.6kHz

100 200 300 400 500 600 700 800 900

Voltage [Vdc]

Power [kW] 600

Storage Current Profile

500

400

300

Storage profile

200 NXI03005A0T0ISFA1A200000

100

NXI02615A0T0ISFA1A200000

smaller device @3.6kHz 0

100

200

300

400

500

600

700

800

900

Voltage [Vdc]

Figure 48. Power unit selection tool example based on storage current profile
Based on the cases in figures above it is advantageous to limit the power at low battery voltage to limit the current to a reasonable value. This helps to allow the use of a smaller frame size. Filter size is also proportional to current. Therefore, high energy storage voltage is preferred from the DC/DC converter sizing perspective.

24-hour support +358 (0)201 212 575 · Email: service@vacon.com
7

vacon · 47

INFORMATION TO ACQUIRE FROM CUSTOMERS

8. INFORMATION TO ACQUIRE FROM CUSTOMERS
It is important to find enablers and limiting factors of the customer system. The following list is, in priority order, the information to be acquired from customer system to continue the discussion of the offering.
1. Single line diagram 2. Short description of usage case / mission profile / wanted behavior 3. Battery (storage) information
· Voltage window [UBat,min, UBat,nom, UBat,max] · Power or current requirement at those voltage points [UBat,min, UBat,nom, UBat,max] · Balance/Maintenance charger? 4. Grid information · Grid code demands? 5. Preferred topology if any (and why) 6. System control overview

Tel. +358 (0) 201 2121 · Fax +358 (0)201 212 285

www.danfoss.com

Vacon Ltd
Member of the Danfoss Group
Runsorintie 7 65380 Vaasa Finland

Document ID:
DPD01887A Rev. A

References

Danfoss A/S GPL Ghostscript 9.55.0