The supplier of the frequency converter braking unit reminds you that in production conditions, we often encounter another problem: how to truly achieve energy feedback from the motor to the DC bus, and then from the DC bus to the AC power grid? Due to the use of uncontrollable rectifier bridges in general frequency converters, other control methods must be adopted to achieve this.
The most effective way to achieve bidirectional energy transfer between the DC circuit and the power source is to use active inverter technology: that is, to invert the regenerated electrical energy into AC power of the same frequency and phase as the grid and return it to the grid, thereby achieving braking.
Schematic diagram of feedback grid braking
As shown in the figure, it is the principle diagram of feedback grid braking, which adopts a current tracking PWM rectifier, which makes it easy to achieve bidirectional power flow and has a fast dynamic response speed. Meanwhile, this topology allows us to fully control the exchange of reactive and active power between the AC and DC sides.
Braking characteristics
a. Widely used in energy feedback braking scenarios of PWM AC transmission, with high energy-saving operation efficiency;
b. Does not produce any abnormal high-order harmonic current components, environmentally friendly;
c. Power factor ≈ 1;
d. In a multi motor transmission system, the regenerative energy of each individual machine can be fully utilized;
e. Save investment and easily control harmonic and reactive power components on the grid side;