For several braking methods of servo motors, we often confuse the effects of electromagnetic braking, regenerative braking, and dynamic braking, and choose the wrong accessories. The dynamic brake is composed of a dynamic braking resistor, which shortens the mechanical feed distance of the servo motor through dynamic braking in the event of a fault, emergency stop, or power failure.
Regenerative braking means that when the servo motor decelerates or stops, the energy generated by braking is fed back to the DC bus through the inverter circuit and absorbed by the resistance-capacitance circuit. The electromagnetic brake is to lock the shaft of the motor through a mechanical device.
The difference between the three
A. Regenerative braking must work when the server is working normally. The motor cannot be braked in the event of a fault, emergency stop, power failure, etc. Dynamic brakes and electromagnetic brakes do not require power when they work.
B. Regenerative braking is done automatically by the system, while the dynamic brake and electromagnetic brake need to be controlled by an external relay.
C. Electromagnetic brake is generally started after SV and OFF, otherwise, it may cause amplifier overload. Dynamic brake is generally started after SV, OFF or main circuit power failure, Otherwise, it may cause the dynamic braking resistor to overheat.
Precautions for choosing accessories
a. Some systems such as transmission devices, lifting devices, etc. require the servo motor to stop as soon as possible. However, in the event of a fault, emergency stop, or power failure, the server cannot decelerate the motor without regenerative braking. At the same time, the mechanical inertia of the system is large, this The dynamic brake should be selected when the dynamic brake is selected according to the weight of the load and the working speed of the motor.
b. For some systems to maintain the static position of the mechanical device, the motor needs to provide a larger output torque and stop for a long time. If the self-locking function of the servo is used, it will often cause the motor to overheat or the amplifier to overload. In this case, choose a motor with an electromagnetic brake.
c. Mitsubishi's servers have built-in regenerative braking units, but when regenerative braking is frequent, it may cause the DC bus voltage to be too high. In this case, a regenerative braking resistor is required. Whether the regenerative braking resistor needs to be equipped separately, and the size of the regenerative braking resistor can be referred to the instructions of the sample. It should be noted that the number of braking times in the sample list is the data when the motor is at no load. In actual selection, first, calculate the inertia ratio according to the load inertia of the system and the motor inertia on the sample. Then divide the number of braking on the sample list by (inertia ratio+1). The data obtained in this way is the permitted number of braking. We are a servo motor manufacturer & supplier. Come to contact us for small business.Tags: servo motor