Servo Motor Usage Instructions_Servo Motor Wiring Details
Currently, there are two main types of rotor structures: one is a squirrel-cage rotor with high-resistivity conductor bars made of high-resistivity conductive material, which is made slender to reduce the rotor's moment of inertia; the other is a hollow cup-shaped rotor made of aluminum alloy with very thin walls, only 0.2-0.3 mm. To reduce the magnetic resistance of the magnetic circuit, a fixed inner stator is placed inside the hollow cup-shaped rotor. The hollow cup-shaped rotor has a very small moment of inertia, responds quickly, and runs smoothly, so it is widely used.
1. Wiring
Power off the control card and connect the signal lines between the control card and the servo. The following lines are mandatory: the analog output line of the control card, the enable signal line, and the encoder signal line output by the servo. After verifying that the wiring is correct, power on the motor, control card, and PC. The motor should not move at this point and can be easily rotated with external force. If not, check the enable signal settings and wiring. Rotate the motor with external force to check if the control card can correctly detect changes in motor position; otherwise, check the encoder signal wiring and settings.
2. Try the direction
For a closed-loop control system, if the direction of the feedback signal is incorrect, the consequences will be disastrous. Enable the servo via the control card. The servo should then rotate at a low speed; this is the so-called "zero drift." Most control cards have instructions or parameters to suppress zero drift. Use these instructions or parameters to see if the motor's speed and direction can be controlled. If not, check the analog wiring and control mode parameter settings. Confirm that a positive value results in the motor rotating forward and the encoder count increasing; a negative value results in the motor rotating backward and the encoder count decreasing. Do not use this method if the motor is under load and has limited travel. Do not apply excessive voltage during testing; below 1V is recommended. If the directions are inconsistent, modify the parameters on the control card or motor to make them consistent.
3. Suppress zero drift
In closed-loop control, zero drift can negatively impact control performance, and it's best to suppress it. Carefully adjust the zero drift suppression parameters on the control card or servo motor to bring the motor speed close to zero. Since zero drift itself has a degree of randomness, it's not necessary to require the motor speed to be absolutely zero.
Servo motors have the function of emitting pulses. So, for every angle a servo motor rotates, it will emit a corresponding number of pulses. This forms a response, or closed loop, with the pulses received by the servo motor. In this way, the system knows how many pulses were sent to the servo motor and how many pulses were received back. This allows for very precise control of the motor's rotation, thereby achieving precise positioning, which can reach 0.001mm.
DC servo motors are divided into brushed and brushless motors. Brushed motors are low in cost, simple in structure, have high starting torque, wide speed range, and are easy to control. However, they require maintenance, which is inconvenient (replacing carbon brushes), generates electromagnetic interference, and has environmental requirements. Therefore, they can be used in cost-sensitive general industrial and civilian applications.
Wiring includes main circuit wiring and control circuit wiring. The main circuit includes the R, S, T three-phase lines and the U, V, W lines connected to the motor. The PLC connects to the driver's CN1 (some drivers include CN1A and CN1B), and the encoder connects to CN2. For detailed information, you can search online for actual wiring diagrams; it will be very clear! The difficulty lies in wiring the PLC output lines to the relay terminal block, which must be done according to the design requirements.
