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A Two-Phase High Step Down Coupled-Inductor Converter for Next Generation Low Voltage CPU
K. Matsumoto,K. Nishijima,T. Sato,T. Nabeshima 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
In this paper, a novel two-phase high step down coupled-inductor converter for next generation low voltage CPU is proposed. This converter has a very high step down characteristic as Vo/Vi = D/4. The switching loss and noise of all switching elements are sufficiently reduced because the drain-source voltages at switching periods are reduced to a quarter of the input source voltage. Low withstand voltage MOSFETs with low on resistance and low Qg(total gate charge) characteristics are possible to use for the all switching elements because the maximum voltage stresses of the main switches and the synchronous rectifier switches are reduced to a half and a quarter of the input source voltage respectively. Further, the branch currents flowed through the paralleled converters are automatically and mostly balanced without the current detection and balance control. The above fine characteristics are simply achieved with three additional capacitors.
High Efficiency Operation for H-Bridge DC-DC Converter
K. Okura,T. Nabeshima,T. Sato,K. Nishijima,H. Yajima 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents two methods of switching operation for higher conversion efficiency and seamless control for wide range of the input voltage in a H-Bridge DC-DC Converter. This converter consists of buck and boost blocks and a feedforward control from the input voltage is employed for the boost block to realize seamless transition between step down and step up operation mode. From the view point of the conduction loss and the switching loss, two methods of the desirable duty ratio of the boost section and different switching frequencies are examined. As a result, higher efficiency was obtained by minimizing the duty ratio of the boost block for wide range of the input voltage and by decreasing the switching frequency of the buck block without increasing output ripple voltage.
Novel Low Cost Ripple Based Controlled Pulse Width Modulator for Fast Transient Response
S.Hirose,K.Ono,T.Sato,T.Nabeshima,K.Nishijima 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents novel pulse width modulation circuit for fast transient response. In the proposed modulator, C-MOS logic inverters are used instead of high speed comparators. Four types of new modulator are proposed and operating principle described in detail. The proposed modulator is applied to a buck converter, and steady state characteristics and frequency response of the proposed modulator are measured with the bread board circuit. From the experimental result, it is found that the proposed modulator has the derivative characteristics as hysteretic PWM controller that has good transient performance. Excellent load and line regulation are obtained. By using C-MOS inverter, compared with conventional hysteretic PWM controller with fast comparator, cost is reduced to one-fifth.
Steady-State Error Reduction by Digital Offset Control for Dc-to-dc Converters
T. Kuroki,T. Sato,T. Nabeshima,K. Nishijima 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a novel algorithm of a digital control that improves a steady-state error of a dc-to-dc switching converter. Instead of the conventional Integral control, the offset control is employed in which the base-duty-cycle of Pulse Width Modulation (PWM) is updated at constant intervals so that the error of the output voltage might become small. The principle of the proposed algorithm is described in detail. The implementation of the algorithm is very simple and the code size becomes small that yield the shortest execute time. Characteristics of the proposed controller are examined, and it is found that the controller has the same characteristics as the conventional integral control. As a result, the steady-state error has been reduced to almost zero.