Magnetic transformer circuit, the circuit frequency of the PZT-based, rather than the current duty cycle to control the fluorescent lamp

Magnetic transformer circuit , the circuit frequency of the PZT -based , rather than the duty cycle to control the fluorescent lamp . UCC3977 between the COMP pin with a pin and OSC formed programmable voltage controlled oscillator. The VCO operating frequency range for the system settings , the frequency range of the excitation frequency must PZT and the normal operating frequency is included . FB pin fluorescent lamp  electric meter  , and through PZT gain versus frequency characteristics can be controlled. PZT gain  electri cenergy meter  to be able to provide the minimum input voltage at the fluorescent lamp voltage, in order to ensure the control loop is always in the right side of the resonance . Work waveform push-pull circuit. N1 and N2 at 50% duty cycle is driven to generate the phase shift. Inductor L1 and L2  Circuit breaker  PZT primary capacitance , drain the N1 and S2 form a half sine wave. In the PZT voltage obtained across the primary near sinusoidal . Fluorescent voltage close to 600 volts in this application . Since the ceramic transformer has a high Q value, the voltage of the fluorescent lamp is a sine wave . To achieve zero- voltage switching , the drain voltage of the next switching cycle must return to zero before. This requires that the LC resonance frequency must be higher than the switching frequency.