Common faults and solutions of Yaskawa robot servo drives

Yaskawa servo drives (servodrives), also known as “Yaskawa servo controller” and “Yaskawa servo controller”, are a controller used to control servo motors. Its function is similar to that of a frequency converter on ordinary AC motors, and it belongs to the servo system The first part is the positioning and positioning system. Generally, the servo motor is controlled through position, speed and torque to achieve the main positioning of the transmission system positioning. It is currently a high-end product of transmission technology. Yaskawa robot system integrated maintenance Yaskawa servo drive repair program.

Common faults and solutions of Yaskawa robot servo drives

1. Yaskawa driver maintenance module DC overvoltage-fault phenomenon: During the shutdown and deceleration process of the inverter, module DC overvoltage faults occurred multiple times, causing the user’s high-voltage switch to trip. The user’s bus voltage is too high, the actual bus of the 6KV power supply is above 6.3KV, and the actual bus of the 10KV power supply is above 10.3KV. When the bus voltage is applied to the inverter, the module input voltage is too high, and the module reports DC bus overvoltage. During the startup process of the inverter, the DC bus of the inverter is over-voltage when the Yaskawa servo drive is running at about 4HZ.

Cause of the fault: During the shutdown process of the inverter, the deceleration time is too fast, causing the motor to be in the generator state. The motor feeds back energy to the DC bus of the module to generate a pumping voltage, causing the DC bus voltage to be too high. Since the factory standard wiring of on-site transformers is 10KV and 6KV, if the bus voltage exceeds 10.3KV or 6.3KV, the output voltage of the transformer will be too high, which will increase the bus voltage of the module and cause overvoltage. Yaskawa servo driver repairs the reverse connection of optical fibers of different phase modules at the same position (for example, the reverse connection of A4 and B4 optical fibers), causing the phase voltage output to be overvoltage.


Properly extend the up/down time and deceleration time.

Increase the overvoltage protection point in the module, now it is all 1150V.

If the user voltage reaches 10.3KV (6KV) or above, change the short-circuited end of the transformer to 10.5KV (6.3KV). Yaskawa servo drive maintenance check whether the optical fiber is plugged incorrectly and correct the incorrectly connected optical fiber.

2. Robot digital AC servo system MHMA 2KW. As soon as the power is turned on during the test, the motor vibrates and makes a lot of noise, and then the driver displays alarm No. 16. How to solve the problem?

This phenomenon is generally due to the driver’s gain setting being too high, resulting in self-excited oscillation. Please adjust parameters N.10, N.11, and N.12 to appropriately reduce the system gain.

3. Alarm No. 22 appears when the robot AC servo driver is powered on. Why?

Alarm No. 22 is an encoder fault alarm. The causes are generally:

A. There is a problem with the encoder wiring: disconnection, short circuit, wrong connection, etc. Please check carefully;

B. There is a problem with the encoder circuit board on the motor: misalignment, damage, etc. Please send it for repair.
4. When the robot servo motor runs at a very low speed, it sometimes speeds up and sometimes slows down, like crawling. What should I do?

The low-speed crawling phenomenon of the servo motor is generally caused by the system gain being too low. Please adjust parameters N.10, N.11, and N.12 to appropriately adjust the system gain, or run the driver’s automatic gain adjustment function.

5. In the position control mode of the robot AC servo system, the control system outputs pulse and direction signals, but whether it is a forward rotation command or a reverse rotation command, the motor only rotates in one direction. Why?

The robot AC servo system can receive three control signals in position control mode: pulse/direction, forward/reverse pulse, and A/B orthogonal pulse. The factory setting of the driver is A/B quadrature pulse (No42 is 0), please change No42 to 3 (pulse/direction signal).

6. When using the robot AC servo system, can servo-ON be used as a signal to control the motor offline so that the motor shaft can be directly rotated?

Although the motor is able to go offline (in a free state) when the SRV-ON signal is disconnected, do not use it to start or stop the motor. Frequent use of it to switch the motor on and off may damage the drive. If you need to implement the offline function, you can switch the control mode to achieve it: assuming that the servo system requires position control, you can set the control mode selection parameter No02 to 4, that is, the mode is position control, and the second mode is torque control. Then use C-MODE to switch the control mode: when performing position control, turn on the signal C-MODE to make the drive work in one mode (i.e. position control); when it needs to go offline, turn on the signal C-MODE to make the The driver works in the second mode (i.e., torque control). Since the torque command input TRQR is not wired, the motor output torque is zero, thus achieving offline operation.

7. The robot AC servo used in the CNC milling machine we developed works in analog control mode, and the position signal is fed back to the computer for processing by the pulse output of the driver. During debugging after installation, when a motion command is issued, the motor will fly. What is the reason?
This phenomenon is caused by the wrong phase sequence of the A/B quadrature signal fed back from the driver pulse output to the computer, forming positive feedback. It can be handled by the following methods:

A. Modify the sampling program or algorithm;

B. Swap A+ and A- (or B+ and B-) of the driver pulse output signal to change the phase sequence;

C. Modify driver parameter No45 and change the phase sequence of its pulse output signal.

8. The motor runs faster in one direction than the other;

(1) Cause of the fault: The phase of the brushless motor is wrong.

Solution: Detect or find out the correct phase.

(2) Cause of failure: When not used for testing, the test/deviation switch is in the test position.

Robot driver maintenance method: Turn the test/deviation switch to the deviation position.

(3) Cause of failure: The position of the deviation potentiometer is incorrect.

Yaskawa drive repair method: Reset.
9. Motor stalls; Yaskawa servo drive maintenance solution

(1) Cause of the fault: The polarity of the speed feedback is wrong.

Solution: You can try the following methods.

a. If possible, move the position feedback polarity switch to another position. (On some drives this is possible

b. If using a tachometer, swap TACH+ and TACH- on the driver.

c. If using an encoder, swap ENC A and ENC B on the driver.

d. If in HALL speed mode, swap HALL-1 and HALL-3 on the driver, and then swap Motor-A and Motor-B.

(2) Cause of the fault: When the encoder speed feedback occurs, the encoder power supply loses power.

Solution: Check the connection to the 5V encoder power supply. Make sure the power supply can provide sufficient current. If using an external power supply, ensure that this voltage is to the driver signal ground.

10. When the oscilloscope checked the current monitoring output of the driver, it was found that it was all noise and could not be read;

Cause of the fault: The current monitoring output terminal is not isolated from the AC power supply (transformer).

Treatment method: You can use a DC voltmeter to detect and observe.

11. The LED light is green, but the motor does not move;
(1) Cause of the fault: The motor in one or more directions is prohibited from operating.

Solution: Check the +INHIBIT and –INHIBIT ports.

(2) Cause of the fault: The command signal is not connected to the driver signal ground.

Solution: Connect the command signal ground to the driver signal ground.

Yaskawa robot servo driver maintenance solution

12. After powering on, the driver’s LED light does not light up;

Cause of failure: The power supply voltage is too low, less than the minimum voltage value requirement.

Solution: Check and increase the power supply voltage.

13. When the motor rotates, the LED light flashes;

(1) Cause of failure: HALL phase error.

Solution: Check whether the motor phase setting switch (60°/120°) is correct. Most brushless motors have a 120° phase difference.

(2) Cause of failure: HALL sensor failure

Solution: Detect the voltages of Hall A, Hall B, and Hall C when the motor rotates. The voltage value should be between 5VDC and 0.

14. The LED light always remains red;

Cause of Yaskawa robot driver failure: There is a fault.

Solution: Cause: overvoltage, undervoltage, short circuit, overheating, driver disabled, HALL invalid.

The above is a summary of some common faults about Yaskawa robot servo drives. I hope it will be very helpful to everyone. If you have any questions about Yaskawa robot teaching pendant, Yaskawa robot spare parts, etc., you can consult: Yaskawa robot service provider

Post time: May-29-2024