• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.3 s.303
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• pp.71-80
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• 2005

This paper proposes a new circuit topology of the half-bridge resonant inverter and presents its digital control scheme. As the proposed half-bridge inverter can be operated in the load-freewheeling modes, pulse width modulation (PWM) control method can be used for the output power control. The proposed half-bridge inverter can keep unity output displacement factor under the load-impedance varying conditions, if a new PWM control scheme based on the resonant frequency tracking algorithm is adopted. In this paper, the operation principle, electrical characteristics and detailed digital control scheme of the proposed half-bridge resonant inverter and loss analysis comparing with a conventional half bridge inverter is described. The experimental results of the proto-type experimental setup to verify the validity of the proposed half-bridge resonant inverter are presented and discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.5
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• pp.479-488
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• 1991

A novel three-phase quasi-resonant dc link inverter (QRI)with a switch connected between dc voltage source and resonant inductor is proposed. According to the state of switching and load current, the operating mode of the proposed inverter scheme is classified into free-wheeling, inverting, and rectifying mode. By examining the behavior of the circuit in each operating mode, an equivalent circuit which represents all the modes in a unified manner is derived. The operating principle of QRI at inverting mode is analyzed, and it is shown that the maximum voltage of resonant dc link is confined to twice the dc source voltage and that both the zero voltage switching of inverter and the zero current switching of inserted switch are guaranteed. An appropriate current control algorithm is suggested, and the opeating characteristics of proposed resonant inverter are verified through both simulation and experiment.