VACON NX OPTBC Resolver Board

RESOLVER OPTION BOARD OPT-BC

This manual is valid for board versions VB00339i or later. The Resolver option board OPT-BC provides the user with an interface to use resolvers as feedback device to the VACON® NXP Drive. The interface provides speed and position data. The OPT-BC includes also encoder simulation output  (HTL level) and secondary encoder input (HTL-level).

Note about absolute angle and different HW and SW versions
Due to differences in hardware and software, the angle given by OPTBC resolver board to application can differ by 180 degrees in the same system. When replacing OPTBC resolver option board in existing installations, care must be taken that angle value does not change accidentally. To prevent this, it is recommended that encoder ID run is always executed when replacing OPTBC resolver option boards in existing installations. This will automatically correct the possible 180 degrees difference that might be induced when replacing OPTBC option board.
Following table shows which OPTBC resolver hardware and software combinations are compatible. For example, if you replace OPTBC with HW version G and software version V005 with OPTBC with hardware version K and software version V013 the angle does not change by 180 degrees. In this case, encoder ID run is not needed but still recommended.

Not performing encoder ID run after replacing OPTBC resolver option board prior to any other use of the AC drive may result in severe harm or injury to equipment and/or persons.

Resolver basics
A resolver is a rotary transformer where the magnitude of the energy through the resolver windings varies sinusoidal as the shaft rotates. A resolver contains one primary winding and two secondary windings, the SIN and COS windings.
Primary winding is in the rotor of the resolver and secondary windings are in the stator. Secondary windings are mechanically displaced 90 degrees from each other.
The primary winding is excited by an AC voltage called the reference voltage (Vr). The induced voltages in the SIN and COS Windings are equal to the value of the Reference Voltage multiplied by the SIN or COS of the angle of the input shaft from a fixed zero point.

Resolver signals

Why resolvers?
When a Motion control application exists in a hot, humid, dusty, oily, or mechanically demanding environment, a resolver-based system is the preferred choice.

Resolver to digital conversion basics
The OPT-BC board sends the Excitation signal to the resolver, and resolver sends sin and cos signals back to the board. In the OPT-BC board, sin and cos signals are converted to incremental encoder pulses by the ASIC circuitry (see picture 1).
The incremental pulses are used for calculating rotation speed in the VACON® NXP control card. The conversion from resolver sin/cos signals to digital pulses is called RTD (Resolver To Digital conversion). Compatible resolver types
Resolver Output voltage: 1.8Vrms 4.0Vrms
Resolver Input voltage: 1.3Vrms 7.5Vrms

Number of poles:

Note
If the number of poles of the resolver is not 2, then the resolver can only work with a motor that has the same number of poles (e.g. a 6 pole resolver with a 6 pole motor ). Maximumtracking rates assume that resolver has 2 poles.

Resolver board features

*tested in zero acceleration

• Note: by selecting 16bit mode, you can improve only position accuracy. Velocity accuracy remains the same (14bit).
• Encoder Simulation Pulses per Revolution and Maximum tracking rate depend on the number of resolver poles.
• Simulated Pulses / rev = 2R ∙ Resolver_Poles / 8
• R = Encoder simulation output resolution

CONFIGURATION

Board parameters and monitoring values Monitor Menu

Parameters menu

Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts

imulated pulses / rev is calculated on the basis of resolution bits(R) and resolver poles. The formula used is:
Simulated Pulses/rev = 2^R * Resolver poles / 8
Example:

Example:

• Resolution bits = 12
• Resolver poles = 2
• Simulated Pulses/rev=2^12 * 2 / 8
• Simulated Pulses/rev = 2^12 * 2 / 8 = 1024
• The absolute position value is from 0 to 4095 (2^12=4096).

Connectors and jumpers

Picture 2 Connector and pin header placement in OPT Board. Pin number 1 is marked with a small square on the X3, X4, X10, X13 and X21.

Terminal data for X1 and X2 connectors

X21 (C-Pulse source selection)

Incremental C-pulse (Zero pulse) to control board is read from the resolver attached to the option board (Default).

C-pulse is External. Read from FRZ input. This feature can be used with special applications for marking position data. Not supported in Standard VACON® NXP applications.

X10 and X13 (Gain select ion)

• SIN and COS feedback signals from the resolver should be in the range of 1.8 4Vrms (between SINHI
• SINLO and COSHI – COSLO). To scale the input signals to an acceptable level we can select 1/3, ⅓ or 1/4 attenuation for the input lines. Following equation can be used to calculate output signal level.
• Transformation for the cor responding resolver is told in resolver datasheets.
• EXC_OUT = excitation output voltage
  SIN Feedback voltage = EXC_OUT * Transformation ratio

1/4 gain for SIN / COS feedback signals from Vrms to 4Vrms

• 1/3 gain for SIN / COS feedback signals from
  2.4 Vrms to 3.24Vrms
• 1/2 gain for SIN / COS feedback signals from
• 1.8 Vrms to 2.39Vrms

X13 sets SIN attenuation and X10 sets COS attenuation. SIN and COS input pairs should all have the same attenuation to keep signals symmetrical.
For example, a resolver that is rated for 5.6Vrms excitation and has a transformation ratio of 0.485 gives output voltage of 2.72Vrms. Excitation voltage and corresponding settings are selected from the table 1 in chapter 2.2.4. In this case exact match is found. Resolver output voltage of 2.72V Vrms fits to the signal range of 1/3 attenuation.

X3 and X4 Excitation Voltage Control

• Resolver option board has an amplifier for adjusting excitation voltage. Jumpers X3-1-4 and X4-1-3 set the amplifier gain and consequently the excitation voltage. Excitation voltage can be set in the range of 1.3Vrms to 7.5Vrms. To get the best possible accuracy, excitation voltage should be selected to be as high as the used resolver allows AND so that the output voltage fits to the given range.
  Excitation frequency is set from the control panel and it should be set prior to connecting the resolver to the option board.
• To set the excitation voltage accurately, measure the excitation voltage when resolver is connected. Notice that the measurement device must be capable of measuring high frequency RMS voltage.
• Typical excitation voltage for each jumper setting can be checked from the table, usable values are highlighted.
• EXC_OUT = target excitation output voltage. This is specified in resolver datasheets (Excitation Voltage)

Now, set the calculated gain with X3 and X4 jumpers. Jumper settings for the desired gain can be found from table. All jumpers attached gives minimum gain and all jumpers open gives maximum gain. Maximum output voltage is limited to the boards internal voltages and is approximately 7.5Vrms. Recommended voltage range is highlighted with blue.
X = Jumper installed

Configuration example
Example Resolver Datasheet

1. Step 1:
   Check resolvers input voltage and select corresponding configuration for jumpers X3 and X4 from the table1.->6.1 V (Use smaller Voltage from the table if exact match is not found = 6.08V)

   X3- 1	X3- 2	X3- 3	X3- 4	X4- 1	X4- 2	X4- 3	EXC_OUT [Vrms] Typical
   		X	X	X	X		6.08
   X	X		X	X	X		6,.3

2. Step 2:
   • Find resolver output voltage from the datasheet or calculate it.
   • Output voltage = input voltage transformation ratio.
   • Output Voltage = 6.08 0.485
   • Output Voltage = 2.95 Vrms
   • 1/4 gain for SIN / COS feedback signals from
   • 3.25 Vrms to 4Vrms
   • 1/3 gain for SIN / COS feedback signals from
   • 2.4 Vrms to 3.24Vrms
   • 1/2 gain for SIN / COS feedback signals from
   • 1.8 Vrms to 2.39Vrms
   • If Output voltage is higher than 4Vrms -> Lower the excitation voltage. ->Use 1/3 gain
     Configure board using the control panel. (Software configuration)

Invert Direction ->This parameter can be used for inverting rotation direction

Reading Rate -> Default 1ms.
In noisy environments this parameter can be used to filter disturbances. Set first to 5ms if the shaft is not running smoothly. 7.3.1.3 Exciting freq -> Select the Exciting frequency as told in specification >In this example 10kHz

Resolution ->Default 12bit ->In slow Speed applications high Resolution can be used.

Planned Max Speed in Example is 1500rpm
Select highest possible accuracy ->16 bit
(16bit) = 7500rpm ∙ 2 / Resolver_Poles
7.3.1.5 Resolver poles = 2 poles

INSTALLATION

WARNING!
Internal components and circuit boards are at high potential when the AC drive is
connected to the power source. This voltage is extremely dangerous and may
cause death or severe injury if you come into contact with it.

Installing the option board
Following installation guidelines should be followed carefully to get the best performance of the system. Improper installation of the system might cause to disturbances which may in RTD conversion generate extra encoder pulses or jitter to the pulse lengths.

• Since the board supports large var iation of resolvers, the used resolver should always be verified before installation.
• The option board OPT-BC can only be used with VACON® NXP drives.
• The option board OPT-BC can be connected to slot C.
• Disconnect the drive from the mains before starting the installation.
• VACON® NXP AC drive
• Remove the cable cover.
  
• Open the cover of the control unit.
• Install the option board in slot C on the control board of the AC drive. Make sure that the grounding plate fits tightly in the clamp. Strip the cable at such distance from the terminal that you can fix it to the enclosure with the grounding clamp.
  Note! We recommend to use always shielded twisted pair cables with resolvers. Use cables that are recommended for encoder and resolver feedback.
  Do not mix signals in twisted pairs.
• Always make grounding contact throughout the full circumference of the cable (360°)
• The cable is weakened where the shield is removed
• Make a sufficiently wide opening for your cable by cutting the grid as wide as necessary.
• Close the cover of the control unit and the cable cover.
  

Installing the resolver
Connect the resolver after setting the jumpers. Use cable clamp in the lower part of the VACON® NXP drive to connect cable shield. Strip the cable so that the shield is exposed only from the part that is fitted to the clamp.

Additional cabling instructions
The resolver and other control cables should not be in parallel with power cables (supply and motor cable).

The feedback signals might also suffer from the noise coming from motor and supply cables. Use shielded symmetrical motor cables. It is recommended to connect the motor cable shield with 360° emc bushing. The motor and supply cables should not be in parallel with resolver signal cable.

DIAGNOSTICS AND TROUBLESHOOTING

The panel shows in the G7.3 that board is OPT-BC. Monitor values from  shows:

1. Resolver Freq (Hz)
2. Resolver Speed (Rpm)
3. Sim. Pulses/rev
4. Encoder 2 Freq
5. Encoder 2 Speed
6. AnIN:C.5*
7. AnIN:C.6*

*Error register bits. Please see chapter 4.3 OPTBC Resolver er ror register bits Parameter values from panel index 7.3.1

1. Invert direction
2. Reading rate
3. Exciting freq (10 / 20 kHz)
4. Resolution bits(10 / 12 bits)
5. Resolver Poles
6. Enc 2 Pulse / Rev
7. Encoder 2 type
8. Simulated pulses/rev is calculated on the basis of resolution bits(R) and resolver poles

The formula used is Simulated Pulses/rev = 2R * Resolver poles / 8.

Example:

• Resolution bits = 12
• Resolver poles = 2
• Simulated Pulses/rev=212 * 2 / 8
• Simulated Pulses/rev = 2^12 * 2 / 8 = 1024
• Lower resolution is used in high speed appl ications. In 10-bit mode the resolver sends 256 pulses /
• revolution and in 12 bit mode 1024 pulses / revolution = 2 .
• The absolute position value is from 0 to 4095 (2^12=4096).

Fault handling
OPTBC Resolver option board reports fault to the application in case where LOS (loss of signal) or LOT (loss of traction) situation is detected. Actions after the fault depends from the application configuration.
The option board informs the application when the situation returns to normal.

LED indicators
There are two LED indicators in the option board:
Yellow Board status LED

Red Error LED (Loss of traction)

Fault conditions:

• Incorrect settings for resolver
• Resolver failure
• Cabling failure

In case of failure, check the jumper settings, cabl ing and resolver assembling.

OPTBC Resolver er ror register bits
Analog input variables ANIN5 and ANIN6 shows error registers of the OPTBC Resolver option board.
These variables can be seen as 7.3.2.6 AnIN:C.5 and 7.3.2.7 AnIN:C.6 monitor values. Application developers can also use this information in application if needed.
ANIN5 shows currently active error register bits.
ANIN6 shows cumulative error register bits after AC drive boot.

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

Documents / Resources

VACON NX OPTBC Resolver Board [pdf] User Manual BC361182932762en-000301, NX OPTBC Resolver Board, NX OPTBC, Resolver Board, Board

References

• User Manual