Characteristics and debugging scheme of AC servo motor

The structure of AC servo motor can be divided into two parts, namely the stator part and the rotor part. The structure of the stator is basically the same as that of the rotary transformer. Two-phase windings are placed in the stator core at an electrical angle of 90 degrees. One group is the excitation winding and the other group is the control winding. AC servo motor is a two-phase AC motor.

When the AC servo motor is in use, a constant excitation voltage Uf is applied to both ends of the excitation winding, and a control voltage Uk is applied to both ends of the control winding. When the voltage is applied to the stator winding, the servo motor will start to rotate quickly. The current passed through the excitation winding and the control winding generates a rotating magnetic field in the motor. The direction of the rotating magnetic field determines the direction of the motor. When the voltage applied to any winding is reversed, the direction of the rotating magnetic field changes, and the direction of the motor also changes. In order to form a circular rotating magnetic field in the motor, it is required that there should be a 90-degree phase difference between the excitation voltage Uf and the control voltage UK. Commonly used methods are:

1) Use the phase voltage and line voltage of the three-phase power supply to form a 90-degree phase shift;

2) Using any line voltage of three-phase power supply;

3) Use phase-shifting network;

4) Connect a capacitor in series in the excitation phase.

Features:

1. Excellent performance. The device has the highest amplifier responsiveness in the industry, greatly shortens the setting time, enhances the vibration suppression function, and improves the mechanical performance by combining a medium inertia motor;

2. Easy to start, simple installation and setting, easy tuning;

3. Excellent scalability, a full range of servo motors matching the machine, and standard products that meet safety standards.

Servo motor debugging method

The servo motor is a generator that controls the operation of mechanical components in the servo system and is a speed-adjusting device that assists the motor.

1. Initialization parameters

Before wiring, initialize the parameters.

On the control card: select the control mode; clear the PID parameters; set the enable signal to be off by default when the control card is powered on; save this state to ensure that the control card is in this state when it is powered on again.

On the servo motor: set the control mode; set the enable to be controlled externally; the gear ratio of the encoder signal output; set the proportional relationship between the control signal and the motor speed. Generally speaking, it is recommended to make the maximum design speed of the servo work correspond to the control voltage of 9V. For example, Sanyo sets the speed corresponding to 1V voltage, and the factory value is 500. If you only plan to make the motor work below 1000 rpm, then set this parameter to 111.

2. Wiring

Power off the control card and connect the signal line between the control card and the servo. The following lines must be connected: the analog output line of the control card, the enable signal line, and the encoder signal line of the servo output. After checking that there are no errors in the wiring, power on the motor and the control card (and PC). At this time, the motor should not move and can be easily turned by external force. If not, check the setting and wiring of the enable signal. Turn the motor with external force to check whether the control card can correctly detect the change in the motor position. Otherwise, check the wiring and setting of the encoder signal.

3. Test direction

For a closed-loop control system, if the direction of the feedback signal is incorrect, the consequences will certainly be disastrous. Turn on the servo enable signal through the control card. This means that the servo should rotate at a lower speed, which is the legendary "zero drift". Generally, there will be instructions or parameters on the control card to suppress zero drift. Use this instruction or parameter to see if the speed and direction of the motor can be controlled by this instruction (parameter). If it cannot be controlled, check the analog wiring and the parameter settings of the control method. Confirm that when a positive number is given, the motor rotates forward and the encoder count increases; when a negative number is given, the motor rotates reversely and the encoder count decreases. If the motor is loaded and has a limited stroke, do not use this method. Do not give too much voltage during the test, it is recommended to be below 1V. If the direction is inconsistent, you can modify the parameters on the control card or motor to make them consistent.

4. Suppress zero drift

In the closed-loop control process, the existence of zero drift will have a certain impact on the control effect, so it is best to suppress it. Use the control card or the servo to suppress the zero drift parameters and carefully adjust them so that the motor speed approaches zero. Since the zero drift itself has a certain degree of randomness, it is not necessary to require the motor speed to be absolutely zero.