Output Voltage Ripple Reduction for Current-Mode Resonant Converter Shogo Katayama, Noriyuki Oiwa, Yasunori Kobori, Anna Kuwana, Haruo Kobayashi Gunma University [email protected] 1. Objective 3A-05 4. Proposed Circuit 5. Simulation 6. Conclusion References 2. Background 1. EMI noise reduction Noise spectrum spread LLC current-mode resonant converter LLC resonant converter 2. Modulation ripple reduction Dual-phase configuration Reverse phase modulation [1] M. Ochiai, Switching Power Supplies, Ohm Publishing (2015). [2] D. Kawahara, S. Abe, S. Motomura, K. Domoto, Y. Ishizuka, T. Ninomiya, M. Shoyama, M. Kaga, “On the Parallel Operation of LLC Current-Mode Resonant Converters in High-Voltage DC Power Distribution System” , IEICE Information and Communication Engineers, Tech. Report (2013). [3] K. Kawamura, T. Yamamoto, K. Hojo, “Circuit Technology of LLC Current Resonant Power Supply” , Fuji Electronic Journal, Vol.87 No.4 (2014) EMI noise generation by current flow Conventional noise reduction Analog filter Shield case 3. LLC Resonant Converter Noise spectrum spread for LLC converter Switching frequency: 350kHz Modulation signal: 500Hz Triangular LC Resonant Before ripple reduction Parallel connection of power stages Modulation ripple 8mV Steady-state ripple 57mV After ripple reduction Reduce modulation ripple Noise spectrum spread by modulating the switching frequency EMI noise reduction Dual-phase configuration LLC resonant converter Each channel switching frequency modulation by reverse phase Modulation ripple reduction Switching frequency: 350kHz Modulate signal: 500Hz triangular Without ripple reduction: 8mV ripple With ripple reduction: 0mV ripple Switching frequency pectrum: -13dB Noise spectrum spread equivalent to before ripple reduction Simulate proposal circuit V ref C Load V in V out VCO Driver Q 2 Q 1 Error Amp ΔV out C i L s1 L s2 L p V ref C Load V in V out C i VCO Driver Q 2 Q 1 Error Amp ΔV out Radiation noise Conduction noise Large scale High cost Proposed noise reduction Noise spectrum spread Frequency Amplitude Without spreading Frequency Amplitude With spreading Feedback output voltage error to resonant frequency 0 5 10 15 20 25 30 35 40 45 50 40 50 60 70 80 Output Voltage f 1 = 52.1 kHz Frequency area usage Modulating switching frequency Modulation ripple Goal Modulation ripple reduction C Load V in V out C i1 VCO Driver Q 12 Q 11 V ref C i2 VCO Driver Q 22 Q 21 Error Amp ΔV out Phase Rev Reverse phase modulation each power stage Modulation ripple 0mV Steady-state ripple 20mV to 56mV Switching frequency spectrum -13dB Switching frequency spectrum -11dB Conditions