“This article introduces in detail the three ways of PLC control servo motor

“

Today, I will explain to you three ways about PLC control servo motor:

1. Torque control

2. Position control

3. Speed ​​mode

1. Torque control

The torque control method is to set the external output torque of the motor shaft through the input of the external analog quantity or the assignment of the direct address. The specific performance is that, for example, if 10V corresponds to 5Nm, when the external analog quantity is set to 5V, the motor shaft is The output is 2.5Nm: if the motor shaft load is lower than 2.5Nm, the motor rotates forward, when the external load is equal to 2.5Nm, the motor does not rotate, and when the external load is equal to 2.5Nm, the motor rotates reversely (usually in the case of a gravitational load).

The set torque can be changed by changing the setting of the analog quantity in real time, or the value of the corresponding address can be changed through communication.

2. Position control

In the position control mode, the rotation speed is generally determined by the frequency of externally input pulses, and the rotation angle is determined by the number of pulses. Some servos can directly assign speed and displacement through communication.

Since the position mode can have very strict control on the speed and position, it is generally used in positioning devices.

3. Speed ​​mode

The rotation speed can be controlled by the input of analog quantity or the frequency of the pulse. The speed mode can also be used for positioning in the outer loop PID control with the host control device, but the position signal of the motor or the position signal of the direct load must be sent to the host. Feedback for operational use.

Take the SINAMICS V90 system as an example.

SINAMICS V90 is divided into two versions according to different applications:

1. Pulse train version (integrated pulse, analog, USS/MODBUS);

2. PROFINET communication version.

SINAMICS V90 pulse version can realize the function of internal positioning block, and has pulse position control, speed control, torque control mode.

The following figure shows the default interface definition under the pulse train command speed control mode (Pti), which conforms to the standard application habits.

Three ways of PLC control servo motor

Only one pulse input channel is allowed to be used at the same time, and other control signals can also be freely assigned to the digital input and output terminals, please refer to the operation manual.

Digital input, supports NPN and PNP two types. The 24V power supply in the wiring diagram is as follows:

(1) 24V power supply for SINAMICS V90. All PTO signals must be connected to a controller using the same 24V power supply, eg SINAMICS V90.

(2) The isolated digital input power supply can use the controller power supply.

(3) The isolated digital output power supply can use the controller power supply.

SINAMICS V90 Servo Drive:

Three ways of PLC control servo motor

Motor holding brake signal (only for SINAMICS V90 200 V drives). The SINAMICS V90 200 V drive requires an external relay to connect the motor holding brake.

System wiring diagram for SINAMICS V90 pulse train version:

Three ways of PLC control servo motor

System wiring diagram for SINAMICS V90 PROFINET version:

Three ways of PLC control servo motor

1. SIMOTICS S-1FL6 low inertia motors SH20, SH30 and SH40 use cable connectors.

2. The brake cable connection shown here is only applicable to the V90 400 V drive. The V90 200 V drive requires an external relay to connect the motor holding brake cable.

3. The SINAMICS V90 PTI driver must be connected to the relay through the setpoint cable, while the SINAMICS V90 PROFINET driver must be connected to the relay through the I/O cable.

4. The I/O cable must be used to realize the brake control of the SINAMICS V90 PROFINET 200 V drive, and to realize the application that requires additional DI/DO in addition to the PROFINET communication.