Current synchronous zero voltage switching resonant topology

A method of converting an input power signal to an output power signal with a resonant circuit and a control circuit for controlling the operating frequency of the resonant circuit, said power converter method comprising:

• sensing the resonant frequency of the resonant circuit;
• controlling the oscillation frequency of an oscillator dependent upon the resonant frequency of the resonant circuit;
• and
• controlling the operating frequency of the resonant circuit dependent upon the oscillation frequency of the oscillator.

A fluorescent lamp system comprising:

• a controller having an oscillator circuit, a synchronous detect circuit and a plurality of control signal outputs for providing transistor control signals dependent upon the oscillator frequency;
• a plurality of transistors coupled to receive said input power signal and provide a square wave voltage signal, each transistor being associated with one of said control signal outputs and having a control input coupled to receive a control signal from the associated control signal output of said controller;
• a resonant circuit controlled by said square wave voltage signal from said plurality of transistors to produce a resonant current and provide a high frequency sine wave output voltage signal;
• at least one fluorescent lamp coupled to receive said high frequency sine wave output voltage signal;
• wherein said synchronous detect circuit includes a frequency detector coupled to detect the resonant frequency of the resonant circuit and to provide an oscillator control signal to control the frequency of the oscillator circuit dependent upon the resonant frequency of the resonant circuit.

A fluorescent lamp system comprising:

• a resonant circuit having a resonant frequency and controlled to produce a resonant current signal and provide a high frequency sine wave output voltage signal;
• and
• a controller having an oscillator circuit and a synchronous detect circuit, wherein:
• the oscillator circuit has a controllable oscillation frequency and adapted to be coupled to control the operating frequency of the resonant circuit;
• and
• the synchronous detect circuit is coupled to detect the resonant frequency of the resonant circuit and to provide an oscillator control signal to control the oscillation frequency of the oscillator circuit dependent upon the resonant frequency of the resonant circuit.

A power supply device for providing an output sine wave power signal, said power supply device comprising:

• a controller having an oscillator circuit, a synchronous detector and a plurality of control signal outputs for providing transistor control signals dependent upon the oscillator frequency;
• a plurality of transistors coupled to receive an input power signal, each transistor being associated with one of said control signal outputs and having a control input coupled to receive a control signal from the associated control signal output of said controller, the control signals controlling the transistors to turn on at a frequency dependent upon the oscillator frequency to provide a square wave voltage signal;
• an output network including a resonant circuit controlled by said square wave voltage signal from said plurality of transistors for producing a resonant current and providing a sine wave output power signal;
• wherein said synchronous detector includes a circuit coupled to detect the resonant frequency of the resonant circuit and to provide an oscillator control signal to control the frequency of the oscillator circuit dependent upon the resonant frequency of the resonant circuit.