There is mechnical braking and electric braking,mechnical braking:the motor shaft is stuck by the mechnical device,make the speed slow,for example the electromagnetic clutch and brake,spring applied brake,electromagnetic clutch.Electric braking:Use more of the electic braking in the application,common electric braking:
1.Short sub braking
When the brake motor winding short sub, using the resistance of the winding itself consumes energy.Energy dissipation as a result of the winding resistance is small, fast, there is a certain risk, may be burning motor.
Concatenated in the motor winding resistance when braking, motor equivalent generators, will have the energy conversion into electricity consumption in the combination of resistance.This method is widely used in all kinds of motor brake, variable frequency control is used.From high to low speed (zero speed), then the frequency of the electrical changes very fast, but the rotor of the motor with load (mechanical) has a larger mechanical inertia, not may soon stop, so was born the potential EU power (voltage) motor, its reverse voltage, contrary to the original state of electric torque, torque and make strong braking torque of the motor, forcing the rotor quickly stopped but because the frequency converter is usually pay - direct - in the main power AC/DC rectifier circuit is not reversible so cannot return to the power grid, the result is main circuit voltage of the capacitor 2 increases, according to pump up voltage, when more than the upper limit set voltage, brake circuit conduction, this is the working process of the brake unit, braking resistor through the power source, voltage drops, thus turned kinetic energy into heat energy consumption to off set the lower limit value. This method of braking is not controllable, braking torque fluctuation, braking time can be set.
Selection of braking resistor experience: (1) the smaller resistance, the greater the braking torque, the greater the current through the brake unit.(2) can't make brake unit working current is greater than the allowed maximum current, otherwise will damage the device;(3) the braking time can human choice;(4) small capacity inverter (7.5 KW) or less is generally inscribed braking unit and braking resistor;(5) is required when the overvoltage in fast brake resistance is too large to discharge, should reduce resistance.
It is mainly used for variable frequency control.In motor stator dc voltage, and the inverter output frequency is zero, then produce the stillness of the constant stator magnetic field, cutting the rotation of the rotor magnetic field to produce braking torque, forcing the motor rotor quickly stopped, this step motor to save all the kinetic energy into electrical energy consumption in the rotor circuit of the motor.
5.Regenerative braking energy
Regenerative braking energy when using active inverter technology to control the motor, when braking power inverter with power grid and the frequency and the phase of the alternating current echo power grid, and power consumption so as to realize the brake on the grid.Energy feedback device system has the advantages of far more than energy consumption brake and dc brake so many units used in recent years are put forward according to the characteristics of combination equipment demands with energy feedback device abroad only ABB, Siemens, Fuji, AnChuan, few companies can provide products such as Finland Vacon is almost blank in China.
6. Shunt capacitance braking
A capacitor discharge type single-phase three-phase servo motor braking method, its character is that: in the rotation of motor need brake, the original power input disconnect, and at the same time will be filled with power capacitor connected to the servo motor winding, discharge through the motor winding, produce direct current magnetic field inside the motor, under the influence of dc magnetic field, make the motor rotor brake, brake motor, capacitor power consumption at the same time, after the brake motor, electrical energy depletion capacitance.Its method the temperature rise of the energy consumption is small, prevent motor burn down, motor long life, good braking effect.This structure is convenient for field replacement, improve the effect of electric braking, improve the reliability of the electric actuator.
TORQE electrical , Transmission Experts.