Nidec Unidrive M700 Troubleshooting

3. Instantaneous overcurrent inspection of OI ac output to check if the motor cable is short circuited; Whether the insulation of the motor has decreased; Reduce the speed loop gain (Pr 03.010).

Check if the encoder feedback is lost during the 7 Over Speed motor overspeed check; Reduce the maximum speed limit (Pr 00.002); If using SSI encoder, set Pr 03.047=1 to bypass the boundary trip.

20 Motor Too Hot Motor I ² t Overheating Check if the load is too heavy; Confirm that the rated current Pr 00.046 of the motor is set correctly; Increase the thermal time constant of the motor (Pr 04.015).

21 OHt Inverter IGBT junction temperature too high reduces switching frequency (Pr 00.041); Strengthen ventilation; Check the cooling fan.

32 Phase Loss Input Phase Loss Check Input Power Supply and Wiring; If using DC power supply, set Pr 06.047=2 to disable phase loss detection.

190 Encoder 2 encoder disconnection check 15 pin D-type port wiring; Confirm that the Pr 03.038 encoder type matches; If necessary, turn off wire breakage detection (Pr 03.040=XXXX0).

In depth analysis of encoder and position feedback faults

The Unidrive M700 series supports multiple feedback devices (incremental) through a 15 pin high-density D-shaped port ABZ、SinCos、Hiperface、EnDat、BiSS、SSI、Resolver）。 The P1 interface is always available, and the P2 interface and encoder simulation output depend on the type selected by P1.

1. Encoder power settings

Terminal 13 offers 5V/8V/15V options, set through Pr 03.036. Common error: The encoder is set to 5V, but 8V or 15V is set, causing damage to the encoder. If the voltage drops due to long-distance 5V power supply, it should be changed to 8V and a 5V voltage stabilization module should be installed on the encoder side.

2. Troubleshooting of wire breakage and phase errors

Encoder 2 (disconnected): Subcodes 11/12/13 correspond to disconnected A, B, and Z channels respectively. Check the corresponding pin soldering and shielding.

Encoder 3 (Phase Error): In RFC-S mode, the UVW commutation signal sequence is incorrect or the SinCos signal polarity is reversed. Rotation self-tuning can be performed again (Pr 00.040=2).

Encoder 4/5/6 (communication encoder timeout/CRC error): Check if the communication baud rate (Pr 03.037) matches; Ensure that the total length of the cable does not exceed 50 meters; Use twisted pair shielded wires and ground the shielding layer.

3. Encoder simulation output is unavailable

If the P1 interface uses AB Servo, FD Servo, or other types that occupy all signal lines, the simulation output and P2 interface will fail. The simulation status can be viewed through Pr 03.086 (0=disabled, 1=fully functional, 2=no Z-pulse). If you need to simulate output, you should choose a type that does not occupy all pins (such as a standard AB encoder).

Parameter optimization and motor performance improvement

1. Motor self-tuning (Autotune)

Self tuning is the foundation for optimizing control performance. Select the appropriate self-tuning mode based on the type of motor:

Recommended self-tuning instructions for operating mode

Measure stator resistance, transient inductance, and power factor using open-loop rotation self-tuning (Pr 00.040=2).

RFC-A (asynchronous) rotation self-tuning (Pr 00.040=2) measures stator inductance and saturation characteristics, with the best performance.

RFC-S (synchronous) rotation self-tuning (Pr 00.040=2) measures phase angle (Pr 03.025), Ld, Lq.

Attention: Rotating self-tuning will accelerate the motor to 2/3 of the rated speed, and the load must be disconnected. Static self-tuning (Pr 00.040=1) can be performed under load, but inductance and phase angle cannot be measured.

2. Speed loop gain adjustment

The proportional gain (Pr 03.010) and integral gain (Pr 03.011) of the speed loop directly affect the dynamic response. You can quickly set it through the following methods:

Manual method: Give the driver a step speed command, observe the analog output feedback with an oscilloscope, increase Kp until a slight overshoot occurs, and then callback by 10%.

Automatic method: Set Pr 03.017 to 4 (low bandwidth 5Hz), 5 (standard 25Hz), or 6 (high bandwidth 100Hz), and the driver will automatically calculate the gain.

If the load inertia is known, mechanical inertia measurement can be performed (Pr 00.040=3 or 4), and the result can be written to Pr 03.018, then Pr 03.017=1 (based on bandwidth) is selected for automatic tuning.

3. Current loop gain

The proportional gain (Pr 04.013) and integral gain (Pr 04.014) of the current loop are automatically calculated through self-tuning. If current oscillation occurs, Pr 04.013 can be appropriately reduced; If the dynamic response is insufficient, it can be increased to 1.5 times the self-tuning value (with an overshoot of about 12.5%).

Fieldbus and communication failure

1. Ethernet communication (M700/M702)

IP address conflict: When using a static IP, ensure that the address is unique; When using DHCP, reserve a fixed IP address for the MAC address in the router.

Modbus TCP timeout: Check the Pr 4.15.009 (Modbus Timeout) setting, which defaults to 100ms. If the network latency is high, it can be increased to 500ms. After a timeout occurs, you can select the action (trip or no action) through Pr 4.15.010.