MultiPhase FullHalf Wave Type Resonant Converters with Automatic Current Balance against Element Variation This paper proposes multiphase full wave and half wave type voltage resonant converters with automatic current balance against the LC elements variation. For resonant converters, the multiphase construction is very complicated because its operating frequency is not stable. We have developed dualphase and fourphase resonant converters with the technique of the peak voltage hold method of the sawtooth signal. On the other hand, the current balance is very important to make the output voltage ripple smaller, but it is easy to be imbalance with the variation of the resonant CR elements. We have developed the automatic current balance technique for both full and half wave type resonant converters for using in dualphase or four phase converter.

EMI Noise Reduction and Output Ripple Cancellation for FullWave Type SoftSwitching Converter This paper proposes a novel EMI noise reduction technology with fullwave type softswitching converter. Using resonance to realize the ZeroVoltage Switching (ZVS) operation, a softswitching converter can realize high efficiency and low EMI noise. However, unnecessary radiation and conduction noises of the input current by the switch are still large. This kind of converter has an operating frequency dependent on the resonant waveform. Since the fixed frequency clock is not used, the frequency modulation of the PWM operation signal is strict and the EMI reduction is difficult. In this paper, we show that in the fullwave type resonant softswitching converter, by modulating the time shift of the resonance end edge, the spectrum of EMI and conduction noises are reduced. At this time, modulation of the resonant operation adversely affects the ZVS operation, and the output ripple also increases. Along with this ripple cancellation circuit, the ZVS operation is also improved to reduce the EMI spectrum by more than 10dB. Furthermore, the output modulation ripple can be suppressed to 1mV.