In the traditional system of frequency conversion and speed regulation composed of general frequency converter, asynchronous motor and mechanical load:

When the potential energy load transmitted by the motor is lowered, the motor may be in regenerative power generation braking state; or when the motor moves from high speed to low speed, such as stopping and decelerating, the frequency can be suddenly reduced, but due to the mechanical inertia of the motor, the motor may be in the regenerative power generation state.

The mechanical energy stored in the drive system is converted into electrical energy by the motor and sent back to the DC circuit of the inverter through the six freewheeling diodes of the inverter. At this time, the inverter is in rectifier state. If the energy consumption measures are not taken in the inverter, this part of energy will lead to the voltage rise of the energy storage capacitor in the intermediate circuit.

If the braking is too fast or the mechanical load is hoist type, this part of energy may damage the frequency converter, so we should consider dealing with this part of energy.

In general inverter, there are two ways to deal with renewable energy

(1) The dynamic braking state is called dynamic braking state when it is dissipated into the artificially set "braking resistance" in parallel with the capacitor in the DC circuit.

(2) When the feedback unit is installed to feed back to the power grid, it is called regenerative braking state.

There is also a braking mode, namely DC braking, which can be used in the case of accurate parking or irregular rotation of brake motor caused by external factors before starting.