Novel Control Schemes for 3-Phase Zero Voltage Switching

The use of phase-locked loop (PLL) in 3-ϕ zero voltage switching (ZVS) by sensing 1 ϕ is brought out. The burst and proportional control schemes for 3-ϕ ZVS using off-the-shelf integrated circuits (IC's) are described. The schemes explained employ zero voltage synchronous switching for both steady-state operation and starting. The proportional control scheme uses a voltage controlled monostable in contrast to the present method of ramp comparison with the control voltage. The experimental results are given for a time base of 8 cycles for proportional-type control with resistive loads.