Control system for an electronically commutated motor

摘要

A circuit for controlling the energization of an electrical load from an AC source. The circuit has a pair of DC lines, and means is provided for rectifying the AC output of the source to apply a DC voltage across the DC lines in the form of a full wave rectified sinusoidal signal. Signal switching means for connection between the DC lines and the load establishes a conductive path therebetween during a variable time interval when the voltage applied by the full wave rectified sinusoidal signal exceeds the voltage across the load, and means including the switching means is provided for chopping the full wave rectified sinusoidal signal to apply pulses to the load during the variable time interval at a frequency which is high with respect to the frequency of the signal. Means connected to the chopping means for modulating the width of the pulses is responsive to an externally derived signal representative of the desired operation of the load, and means is responsive to the load current for modifying the externally derived signal to maintain the amplitude of the load current below a predetermined level whereby a high power factor is presented to the AC source during a predetermined range of operation of the load.P PA laundering apparatus, a method of operating a laundry machine, a control system for an electronically commutated motor, and a method of operating an electronically commutated motor are also disclosed.