Variable speed motor drive with integrated motor heating systems and methods

An environmental conditioning system, comprising:

• a motor comprising stator windings;
• a variable speed drive (VSD) configured to drive the motor during an on-cycle and to heat the stator windings during an off-cycle, wherein the variable speed drive comprises:
• a rectifier configured to convert alternative-current (AC) power input to a direct-current (DC) power output;
• a DC bus coupled to the rectifier and comprising a DC bus transistor, wherein the DC bus transistor is configured to:
• pre-charge a DC capacitor of the DC bus to drive the motor during the on-cycle;
• and
• receive a gate pulse with a duty cycle during the off-cycle, wherein the gate pulse is configured to heat the stator windings;
• and
• an inverter comprising a plurality of inverter switches, wherein the inverter is configured to:
• receive the gate pulse applied to the DC bus transistor;
• and
• transmit the gate pulse to one of the stator windings to prevent accumulation of moisture on the one of the stator windings;
• and
• a controller communicatively coupled to the variable speed drive, wherein the controller is configured to:
• determine a temperature differential between a temperature of the motor and an ambient temperature during the off-cycle;
• compare the temperature differential to a threshold temperature differential;
• determine a value of the duty cycle of the gate pulse based on the comparison of the temperature differential to the threshold temperature differential;
• and
• provide the gate pulse having the duty cycle with the value to the DC bus transistor during the off-cycle.

A method for driving a motor at various speeds and providing heat to motor windings of the motor, using a variable speed drive, comprising:

• pre-charging a DC capacitor of a DC bus of the variable speed drive during an off-cycle using a DC bus transistor, wherein pre-charging the DC capacitor enables driving the motor during an on-cycle, wherein the variable speed drive drives the motor at the various speeds during the on- cycle and provides heat to the motor windings during the off-cycle;
• determining a temperature differential between a temperature of the motor and an ambient temperature during the off-cycle;
• determining a value of a duty cycle of a gate pulse based on a comparison of the temperature differential with a threshold temperature differential;
• providing the gate pulse having the duty cycle with the value to the DC bus transistor during the off-cycle;
• and
• transmitting the gate pulse having the duty cycle with the value to the motor windings to heat the motor windings and prevent accumulation of moisture on the motor windings.