Q
Panasonic digital AC servo system MHMA2KW, when the test machine is powered up, the motor will vibrate and there is a lot of noise, then the drive will appear on the 16th alarm, how to solve it?
A
This phenomenon is generally caused by the driver’s gain setting being too high, resulting in self-oscillation. Please adjust parameters No.10, No.11, and No.12 to reduce the system gain as appropriate. (Refer to the contents of the gain adjustment in the User’s Guide)

Q
When the Panasonic AC servo drive is powered on, the number 22 alarm appears. Why?
A
Alarm No. 22 is an encoder fault alarm, which is generally caused by:
A. There are problems with the encoder wiring: disconnection, short circuit, wrong connection, etc., please check it carefully;
B. There is a problem with the encoder on the motor: misplacement, damage, etc. Please send it for repair.

Q
When the Panasonic servo motor is running at a very low speed, it is fast and slow, like crawling. What should I do?
A
The low-speed creep of the servo motor is generally caused by the system gain being too low. Please adjust parameters No.10, No.11, No.12, adjust the system gain appropriately, or run the drive automatic gain adjustment function. (Refer to the contents of the gain adjustment in the User’s Guide)

Q
In the position control mode of the Panasonic AC servo system, the control system outputs the 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?
A
In the position control mode, the Panasonic AC servo system can receive three kinds of control signals: pulse/direction, forward/reverse pulse, and A/B quadrature pulse. The factory setting of the drive is A/B quadrature pulse (No42 is 0), please change No42 to 3 (pulse/direction signal).

Q
In the use of Panasonic AC servo system, can servo-ON be used as a signal to control the motor offline so as to directly rotate the motor shaft?
A
Although the motor can be taken offline (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 may damage the drive. If the offline function needs to be implemented, it can be realized by switching the control mode: assuming that the servo system needs position control, the control mode selection parameter No. 02 can be set to 4, that is, the first mode is position control, and the second mode is torque control. . Then use C-MODE to switch the control mode: when performing position control, make the signal C-MODE open, so that the driver works in the first mode (ie, position control); when it needs to be offline, the signal C-MODE is closed. When the driver is operated in the second mode (ie, torque control), since the torque command input TRQR is not wired, the motor output torque is zero, thereby achieving offline.

Q
In the CNC milling machine we developed, the Panasonic AC servo works in the analog control mode. The position signal is fed back to the computer by the pulse output of the driver. When the machine is commissioned after the installation, the motor command is issued and the motor is flying. What is the reason?
A
This phenomenon is caused by the wrong phase sequence of the A/B quadrature signal fed back to the computer by the driver pulse output, and the positive feedback is formed. It can be processed by the following methods:
A. modify the sampling program or algorithm;
B. Oppose the A+ and A- (or B+ and B-) of the driver pulse output signal to change the phase sequence;
C. Modify the drive parameter No45 to change the phase sequence of its pulse output signal.

Q
In a test equipment we developed, we found that the Panasonic AC servo system has some interference with our detection device. What methods should be generally used to eliminate it?
A
Since the AC servo drive adopts the inverter principle, it is a prominent interference source in the control and detection system. In order to reduce or eliminate the interference of the servo driver to other electronic devices, the following methods can generally be used:
A. The grounding end of the driver and motor should be reliably grounded;
B. The power input of the driver is coupled with an isolation transformer and a filter;
C. Use shielded wires for all control signals and sense signal lines.
The interference problem is a very difficult problem in electronic technology. There is no fixed method to completely eliminate it. It is usually based on experience and experiment to find anti-interference measures.

Q
Why is the servo motor not lost?
A
The servo motor driver receives the feedback signal from the motor encoder and compares it with the command pulse to form a semi-closed loop control of the position. Therefore, the servo motor does not lose step, and each command pulse can be reliably responded.

Q
How to consider the power supply problem of Panasonic servo?
A
At present, almost all Japanese-made AC servo motors are three-phase 200V power supply, and domestic power supply standards are different, so it must be solved as follows:
A. For AC servo below 750W, under normal circumstances, single-phase 220V can be directly connected to the L1 and L3 terminals of the driver;
B. For other types of motors, it is recommended to use a three-phase transformer to change the three-phase 380V into three-phase 200V and connect to the L1, L2, and L3 of the driver.

Q
What should you pay special attention to when mechanically mounting a servo motor?
A
Since the rotary encoder is mounted on the rear end of each servo motor, it is a very fragile precision optics, and excessive impact will definitely damage it.

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