Suppliers of frequency converter supporting equipment remind you that in traditional frequency control systems composed of general frequency converters, asynchronous motors, and mechanical loads:
When the potential load transmitted by the electric motor is lowered, the electric motor may be in a regenerative braking state; Or when the motor stops or decelerates from high speed to low speed, the frequency may suddenly decrease, but due to the mechanical inertia of the motor, it may be in a regenerative power generation state.
The mechanical energy stored in the transmission system is converted into electrical energy by the electric motor and sent back to the DC circuit of the frequency converter through the six freewheeling diodes of the inverter. At this point, the inverter is in a rectified state. If no measures are taken to consume energy in the inverter, this energy will cause the voltage of the energy storage capacitor in the intermediate circuit to rise.
If the braking is too fast or the mechanical load is a hoist, this energy may cause damage to the frequency converter, so we should consider disposing of this energy.
In general frequency converters, there are two most commonly used methods for processing regenerated energy:
(1) The dissipation into the artificially set "braking resistor" in parallel with the capacitor in the DC circuit is called the dynamic braking state.
(2) Installing a feedback unit to feed back to the power grid is called feedback braking state (also known as regenerative braking state).
There is another braking method, namely DC braking, which can be used in situations where accurate parking is required or when the brake motor rotates irregularly due to external factors before starting.