The braking unit supplier reminds you that the regenerative braking of the frequency converter refers to the direction of rotation speed opposite to the direction of motor torque. For example, during deceleration, when the rotor speed is above synchronous speed due to the inertia of the load, the motor is in a regenerative braking state. To convert mechanical energy into electrical energy, the regenerative braking state of the consumed electrical energy must be converted or discarded.
Energy consumption type:
This method involves paralleling a braking resistor in the DC circuit of a frequency converter, and controlling the on/off of a power transistor by detecting the DC bus voltage. When the DC bus voltage rises to around 700V, the power transistor conducts, passing the regenerated energy into the resistor and consuming it in the form of thermal energy, thereby preventing the rise of DC voltage.
Due to the inability to utilize regenerated energy, it belongs to the energy consumption type. As an energy consuming type, its difference from DC braking is that it consumes energy on the braking resistor outside the motor, so the motor will not overheat and can work more frequently.
Parallel DC bus absorption type:
Suitable for multi motor drive systems (such as stretching machines), in which each motor requires a frequency converter, multiple frequency converters share a grid side converter, and all inverters are connected in parallel to a common DC bus.
In this system, there is often one or several motors working normally in the braking state. The motor in the braking state is dragged by other motors to generate regenerative energy, which is then absorbed by the motor in the electric state through a parallel DC bus. If it cannot be fully absorbed, it will be consumed through a shared braking resistor. The regenerated energy here is partially absorbed and utilized, but not fed back into the power grid.
Energy feedback type:
The energy feedback type inverter grid side converter is reversible. When regenerative energy is generated, the reversible converter feeds back the regenerative energy to the grid, allowing the regenerative energy to be fully utilized. But this method requires high stability of the power supply, and once there is a sudden power outage, inversion and overturning will occur.