Brake failure in variable frequency drive motors

A method of handling a brake failure in a variable frequency drive system maintaining a load, comprising:

• determining, by a controller of the variable frequency drive system, that a brake has failed while a motor of the variable frequency drive system is stopped;
• in response to the determination that the brake has failed, determining that power to the controller from a power supply has been interrupted;
• in response to the determination that power to the controller from the power supply has been interrupted, determining that a direct current (DC) voltage across a DC link bus in the controller is below a first threshold value;
• and
• in response to the determination that the DC voltage across the DC link bus in the controller is below the first threshold value, driving the motor at a faster speed.

A crane system, comprising:

• a variable frequency drive motor system including a controller coupled to a variable frequency drive motor;
• a winding drum coupled to the motor, the motor configured to drive the winding drum to rotate such that a load is capable of rising and lowering;
• wherein, the controller is configured to:
• determine that a brake coupled to the motor has failed;
• determine that power to the controller from a power supply has been interrupted;
• and
• in response to a determination that a direct current (DC) voltage across a DC link bus in the controller is below a first threshold value, driving the motor at a faster speed.