Abstract: A hybrid motor for powering a compressor of a chiller system includes a first rotor portion and a first stator portion configured as a permanent magnet motor and a second rotor portion and a second stator portion configured as a reluctance motor. The second rotor portion includes a reluctance-type rotor, and the second stator portion includes electromagnetic windings capable of inducing a rotary magnetic field. The first rotor portion and the second rotor portion are attached to a common drive shaft. The reluctance motor is arranged to generate start-up torque and initiate rotation of the drive shaft until the drive shaft achieves a predetermined rotational speed. The permanent magnet motor is arranged to power the drive shaft between the predetermined rotational speed and a maximum rotational speed.

Abstract: A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive is arranged to receive an input AC voltage at a fixed AC input voltage and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source providing the input AC voltage. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter. The DC link filters and stores the DC voltage from the converter. An inverter is connected to the DC link. A motor connectable to the compressor for powering the compressor. An active filter connected in parallel with the motor. The active filter is arranged to generate high frequency currents having a magnitude and opposite polarity, with respect to the output AC power of the variable speed drive. The high frequency currents generated by active filter substantially cancel out high frequency currents flowing into the motor.

Abstract: A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive is arranged to receive an input AC power at a fixed AC input voltage and fixed input frequency and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source providing the input AC voltage. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter. The DC link is arranged to filter and store the DC voltage from the converter. A first inverter and a second inverter are each connected to the DC link. A motor includes stator windings connected between the first inverter and the second inverter to power the motor by the output AC power from the first inverter and the second inverter. The motor is connectable to a compressor of the chiller system to power the compressor. The motor may be a permanent magnet synchronous motor.

Abstract: A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive is arranged to receive an input AC voltage at a fixed AC input voltage and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source providing the input AC voltage. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter. The DC link filters and stores the DC voltage from the converter. An inverter is connected to the DC link. A motor connectable to the compressor for powering the compressor. An active filter connected in parallel with the motor. The active filter is arranged to generate high frequency currents having a magnitude and opposite polarity, with respect to the output AC power of the variable speed drive. The high frequency currents generated by active filter substantially cancel out high frequency currents flowing into the motor.

Abstract: A hybrid motor for powering a compressor of a chiller system includes a first rotor portion and a first stator portion configured as a permanent magnet motor and a second rotor portion and a second stator portion configured as a reluctance motor. The second rotor portion includes a reluctance-type rotor, and the second stator portion includes electromagnetic windings capable of inducing a rotary magnetic field. The first rotor portion and the second rotor portion are attached to a common drive shaft. The reluctance motor is arranged to generate start-up torque and initiate rotation of the drive shaft until the drive shaft achieves a predetermined rotational speed. The permanent magnet motor is arranged to power the drive shaft between the predetermined rotational speed and a maximum rotational speed.

Abstract: A drive system for a compressor of a chiller system includes a variable speed drive. The variable speed drive receives an input AC power at a fixed input AC voltage and a fixed input frequency, and provides an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter connected to an AC power source. The converter is arranged to convert the input AC voltage to a DC voltage. A DC link is connected to the converter and configured to filter and store the DC voltage from the converter. An inverter is connected to the DC link. A motor is connectable to the compressor for powering the compressor. A controller is arranged to control switching in the converter and the inverter. The controller is arranged to apply randomized pulse width modulation to vary the switching frequency of transistors in the converter and the inverter at each switching cycle. The motor may be a permanent magnet synchronous motor.