Patent ID: 7233112

Claim:
A method of regulating a switching PWM power supply having a duty cycle in order to supply a power output signal having a desired power output level in a range from a minimum to a maximum power output level, said method comprising: applying an AC sinusoidal input signal to a solid state switching section, the AC sinusoidal input signal having alternating positive and negative half cycles separated by zero crossings and each having a peak; controlling the solid state switching section to include in the output signal a variable portion of the power of the AC sinusoidal input signal; said controlling step including, in a first segment of the range, driving the solid state switching section throughout the full half cycle of the AC sinusoidal input signal with a pulse width modulation signal; and said controlling step further including, in a second segment of the range, driving the solid state switching section in a first portion of the half cycle of the AC sinusoidal input signal with a pulse width modulation signal, and in a second portion of the half cycle of the AC sinusoidal input signal, placing the solid state switching section continuously in a condition of full conduction.