ZVS configurations

Zero voltage crossings buck chopper configuration

Zero Voltage Switching (ZVS) in Buck Chopper

In conventional buck converters (buck choppers), the main power switch (MOSFET/IGBT) usually turns ON and OFF at non-zero voltage, which causes significant switching losses, heating, and EMI (Electromagnetic Interference).

To overcome this, the Zero Voltage Switching (ZVS) technique is introduced. In a ZVS-configured buck chopper, the switch is turned ON only when the voltage across it is zero, thereby reducing switching losses.How ZVS is Achieved

• An auxiliary resonant circuit (consisting of a resonant inductor and capacitor) is added to the basic buck converter.
• Before the switch turns ON, the resonant circuit discharges the parasitic output capacitance of the switch to zero volts.
• The main switch then turns ON under zero-voltage conditions.
• During turn-OFF, the resonant circuit ensures that the voltage across the switch rises smoothly, minimizing stress.

Key Features of ZVS Buck Chopper

1. Reduced switching losses → Higher efficiency, especially at high switching frequencies.
2. Lower EMI → Smooth transitions minimize high-frequency noise.
3. Improved thermal performance → Less heating of power devices.
4. High-frequency operation possible → Allows smaller inductors and capacitors.

Applications

• Switched-mode power supplies (SMPS)
• Electric vehicle converters
• Renewable energy converters (solar PV, fuel cell systems)
• High-efficiency motor drives