The regenerative resistor is the first internal word of Taiwan-funded enterprises, and now it has become a common word in the inverter industry and the server industry. In fact, the regenerative resistor is in the system where the inverter drives the motor. It is realized by small frequency. At the moment when the frequency decreases, the synchronous speed of the motor stator decreases, while the rotor speed of the motor does not change due to the mechanical inertia.
When the stator synchronous speed is less than the rotor speed, the phase of the rotor current changes by almost 180 degrees, and the motor changes from the electric state to the power generation state; at the same time, the torque on the motor shaft becomes the braking torque, which makes the motor speed Descending rapidly, the motor is in regenerative braking.
The EBW shunt resistor
by the motor is fed back to the DC circuit after full-wave rectification by the freewheeling diode. Since the electric energy of the DC circuit cannot be fed back to the power grid through the rectifier bridge, it is only absorbed by the capacitor of the inverter itself. Although other parts can consume electric energy, the capacitor still has a short-term charge accumulation, forming a "pumping voltage", which makes the DC voltage rise.
Excessive DC voltage will damage all parts of the device. Therefore, necessary measures must be taken to deal with this part of the regenerative energy when the load is in the state of dynamic braking. The braking resistor is to consume the regenerative energy of the motor in the form of thermal energy, thereby protecting the safety of the equipment.