What is Regenerative Braking?
If you are getting an “Over voltage” error in your drivers due to the motors you use in your system, your system is probably exposed to regenerative energy.
What is the Regenerative Energy?
While electric motors consume energy during acceleration and sustained motion, they tend to generate energy during rapid deceleration or electric braking. In motor driver circuits, this energy from the motor is called “Regenerative Energy” and is fed back to the DC supply line. Depending on the amount of energy supply voltage, this back-up can reach critical levels for the drive electronics and other connected electronic circuits. It may cause you to encounter an “over Voltage” error in motor drivers.
This is a common problem in applications that require high dynamic movements or where the motor is driven by external force. As long as the amount of energy is fairly small, adding a capacitor between the positive and negative supply and adding appropriate diodes will be helpful and sufficient. Beyond that, special brake chopper circuits with power resistors are required to convert excess energy into heat.
Let’s examine this situation through an example
It was used in Velocity mode in 48V 400W BLDC Motor application. In case of sudden load change in the motor, the drivers would shut themselves down and give an “over valtage” error warning. It was determined that this energy was regenerative energy.
The regenerative energy released in the system is calculated as 80W.
As a solution, the first way was to connect a 10,000uF capacitor group and diode in parallel between the DC power supply and the motor driver, but this solution was able to absorb one quarter of the regenerative energy we wanted to spend. This solution failed.
The energy released as a result of the tests and solutions had to be spent in a controlled manner at the appropriate load. Brake chopper circuit was included in the system and the problem was solved by consuming the energy released on resistors with suitable value.