The braking unit supplier reminds you that every frequency converter has a braking unit (low-power is the braking resistor, high-power is the high-power transistor GTR and its driving circuit), low-power is internally manufactured, and high-power is externally manufactured.
When the working machinery requires rapid braking, and within the required time, the regenerative energy of the frequency converter cannot be stored in the intermediate capacitor within the specified voltage range or the internal braking resistor cannot consume it in time, causing overvoltage in the DC part, an external braking component needs to be added to accelerate the consumption of regenerative energy.
Is the variable frequency motor in a generating state when parked, as it is equipped with a mechanical brake?
In general, when the frequency converter stops too quickly, the motor will provide feedback energy to the frequency converter, and the motor will be in a generating state It can be determined whether the motor is in a generating state by observing the bus voltage of the frequency converter. 380V AC input. The DC voltage is around 550V.
Is the braking unit of the frequency converter working at this time?
After overvoltage of the frequency converter. The general braking unit has a braking threshold. Exceeding this threshold. The braking unit will work.
Reasons for brake unit damage
(1) Power mismatch, the power of the braking unit is too small (resistor or chopper is too small) to consume so much kinetic energy in a short period of time.
(2) The load has exceeded the maximum allowable power of the braking unit due to certain reasons.
(3) The brake unit has poor heat dissipation due to dust or other reasons. Make it overheated and damaged.
(4) The braking unit was damaged due to an internal short circuit caused by conductive dust.