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Hybrid frequency modulation for pwm-integrated resonant converters

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Ecwaytech

This paper presents a unique hybrid-frequency modulation method for extending the input range of PWM-integrated resonant converters while maintaining high conversion efficiency. The modulation scheme reduces core and conduction losses by decreasing applied volt-seconds at the transformer and improving switching period utilization. It also maintains zero current switching, minimizes switching loss, and eliminates circulating energy across the entire operating range. Experimental results from a 180W prototype show over a 4% weighted efficiency improvement using this proposed method.

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HYBRID-FREQUENCY MODULATION FOR PWM-INTEGRATED RESONANT CONVERTERS ABSTRACT: This paper presents a unique modulation method for extending the input range of pulse-width modulation (PWM)-integrated resonant converters, such as the isolated boost resonant converter, while maintaining high conversion efficiency. The technique includes primarily the hybridizing of constant-on, constant-off, and fixed-frequency control depending only on the required duty cycle. The modulation scheme reduces core loss and conduction loss dramatically by decreasing the applied volt-seconds at the transformer and improving the switching period utilization. With hybrid-frequency control, the circuit also maintains zero current switching for the output diodes, minimizes switching loss, and eliminates circulating energy at the transformer across the entire operating range. It also allows for a predictable voltage gain, dependent only on duty cycle and transformer turns ratio. A detailed loss analysis is provided and verified against a 180 W experimental prototype, with an input range of 12-48 V and a switching frequency range of 30-70 kHz. Implementation issues are also handled with a variety of solutions for realizing the modulation scheme. Experimental results show greater than 4% weighted efficiency improvement in the prototype using the proposed method.

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Hybrid frequency modulation for pwm-integrated resonant converters

  • 1. HYBRID-FREQUENCY MODULATION FOR PWM-INTEGRATED RESONANT CONVERTERS ABSTRACT: This paper presents a unique modulation method for extending the input range of pulse-width modulation (PWM)-integrated resonant converters, such as the isolated boost resonant converter, while maintaining high conversion efficiency. The technique includes primarily the hybridizing of constant-on, constant-off, and fixed-frequency control depending only on the required duty cycle. The modulation scheme reduces core loss and conduction loss dramatically by decreasing the applied volt-seconds at the transformer and improving the switching period utilization. With hybrid-frequency control, the circuit also maintains zero current switching for the output diodes, minimizes switching loss, and eliminates circulating energy at the transformer across the entire operating range. It also allows for a predictable voltage gain, dependent only on duty cycle and transformer turns ratio. A detailed loss analysis is provided and verified against a 180 W experimental prototype, with an input range of 12-48 V and a switching frequency range of 30-70 kHz. Implementation issues are also handled with a variety of solutions for realizing the modulation scheme. Experimental results show greater than 4% weighted efficiency improvement in the prototype using the proposed method.