US Patent 7626349 Low noise heating, ventilating and/or air conditioning (HVAC) systems

A heating, ventilating and/or air conditioning (HVAC) system includes a system controller, a motor controller, an air-moving component, and a permanent magnet motor having a stationary assembly, a rotatable assembly in magnetic coupling relation to the stationary assembly, and a shaft coupled to the air-moving component. The motor controller is configured for performing sinewave commutation in response to one or more control signals received from the system controller to produce continuous phase currents in the permanent magnet motor for driving the air-moving component. By using sinewave commutation (in contrast to square wave commutation), the noise and vibration produced by the HVAC system is markedly reduced.