System and method for protecting a motor drive unit from motor back EMF under fault conditions

A motor drive unit protection system comprising:

• at least one switch configured to be connected between a motor drive unit and a plurality of motor leads of a motor driven by the motor drive unit;
• a controller configured to monitor at least one of the motor drive unit and the motor to determine a fault condition indicative of the motor potentially operating as a generator;
• and
• wherein, upon determining the fault condition, the controller is configured to cause the at least one switch to connect the plurality of motor leads together to protect the motor drive unit from the motor when the motor is operating as a generator.

A motor system comprising:

• a permanent magnet motor configured to drive a load and having a plurality of leads designed to receive operational power to drive the permanent magnet motor;
• a motor drive unit configured to condition power received from a power supply and deliver operational power through the plurality of leads to drive the permanent magnet motor;
• a fault protection system arranged between the permanent magnet motor and the motor drive unit comprising:
• at least one switch configured to isolate the plurality of leads from one another in a first position and short the plurality of leads together in a second position;
• and
• a controller configured to monitor the plurality of leads to detect at least one of a voltage increase and a current increase indicative of a fault condition and control the at least one switch to move from the first position to the second position upon detecting the at least one of the voltage increase and the current increase indicative of the fault condition to contain power generated by the permanent magnet motor within the permanent magnet motor during the fault condition.