Masahiko Hirokawa

Improvement of transient response in high-current output DC-DC converters

Concerning a low-voltage and high-current output DC-DC converter such as a voltage regulator module used for a 64-bit microprocessor, synchronization with paralleled current-doubler rectifiers has been considered for improvement in dynamic response. As a result, the output voltage deviation of 50 mV at a slew rate of 300 A//spl mu/s has been performed on a prototype with an output of 1.3 V/130 A.

Stability improvement of distributed power system by using full-regulated bus converter

The bus architecture, consisting of bus converter and POLs (point of load), has become very popular since POL can respond to some demands of multi power supply voltage, low driving voltage and series sequence/tracking of LSI with more flexibility than isolated DC-DC solution. However, the customer suffers the system instability issue caused by impedance overlap between the bus converter and POL. Bus converter has three types i) un-regulated, ii) semi-regulated, iii) full-regulated, and each type has different output characteristic. This makes matter more complex to understand and difficult to resolve the instability phenomena. This paper presents, the availability of full-regulated bus converter for system stability as compared with un-regulated and semi-regulated case, and is examined analytically and experimentally. As a result, it has been found that in the case of full-regulated bus converter, the bandwidth is extended in the presence of feedback loop due to damping of output impedance peak, and achieved higher stability.

Stability Comparison of Three Control Schemes for Bus Converter in Distributed Power System

Recently, the distributed power system consists of bus converter and POL is usually used for IT infrastructure equipment. The system may become unstable depending on the bus converter design even if each converter has stable operation. Then, the bus voltage is oscillated. Recently, stability problems in distributed power system become series. It is required to overcome these problems as soon as possible. This paper investigates, the improvement of the system stability by the control method. As a result, the full-regulated bus converter is the best as a control method of the bus converter because the full-regulated bus converter can reduce the bus voltage oscillation and correspond to the input voltage variation flexible by the regulation.

Stability Design Consideration for On-Board Distributed Power System Consisting of Full-Regulated Bus Converter and POLs

The power supply system which requires the low-voltage / high-current output has been changing from conventional centralized power system to distributed power system. The distributed power system consists of bus converter and POL. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the stability design for on-board distributed power system consisting of full-regulated bus converter and POLs. The output impedance of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. As a result, the standard of the discrimination of stability on a frequency response of input and output impedance is clarified. Furthermore, the design process for system stability is proposed.

Optimal intermediate bus capacitance for system stability on distributed power architecture

The power supply system which requires the low-voltage / high-current output has been changing from conventional centralized power system to distributed power system. The distributed power system consists of bus converter and POL. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the output impedance design for on-board distributed power system by means of full- regulated bus converter. The output impedance peak of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. Furthermore, the optimal intermediate bus capacitance design for system stability is proposed.

Output Impedance Design Consideration of Three Control Schemes for Bus Converter in On-Board Distributed Power System

The power supply system which requires the low-voltage/high-current output has been changing from conventional centralized power system to distributed power system. The distributed power system consists of bus converter and POL. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the output impedance design for on-board distributed power system by means of three control schemes of bus converter. The output impedance peak of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. Furthermore, the design process of each control schemes for system stability is proposed.

Optimal design of bus converter in on-board distributed power architecture

The power supply system which requires the low-voltage / high-current output has been changing from conventional centralized power system to distributed power system. The distributed power system consists of bus converter and POL. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the output impedance design for on-board distributed power system by means of three control schemes of bus converter. The output impedance peak of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. Furthermore, the design process of each control schemes for system stability is proposed.

Study of Stabilization Design for On-Board Distributed Power Architecture

The bus architecture consisting of bus converter and Point of Load (POL) is generally used as distributed power supply system for IT infrastructure equipments. The most important factor is the system stability in bus architecture design. The overlap between the output impedance of bus converter and input impedance of POL causes system instability, and it has been an actual problem. Increasing the bus capacitor, system stability can be reduced easily. However, due to the limited space on the system board, increasing of bus capacitors is impractical. The urgent solution of the issue is desired strongly. This paper presents the stability design for on-board distributed power system consisting of full-regulated bus converter and POLs. The output impedance of the bus converter and the input impedance of the POL are analyzed, and it is conformed by experimentally for stability criterion. As a result, the standard of the discrimination of stability on a frequency response of input and output impedance is clarified. Furthermore, the design process for system stability is proposed.

Analysis of high frequency gate driver using push-pull LC self-excitation oscillator

The development of techniques for integrated circuits has driven their miniaturization. The reactance components of converters can be miniaturized by using high switching frequency. Therefore the resonant converters are useful because of the low switching loss in semiconductor switches. At the resonant converters, raising or lowering of output voltage is fundamentally controlled by the switching frequency. For high frequency switching in main switch, high frequency driver is required. However, it is difficult to obtain comparators capable of high frequency operation. To overcome this, we have examined the self-excitation LC oscillation circuit for its use in the main switch drive circuit. It is important to consider the Miller effect of MOSFET about the self-excitation LC oscillation circuit analysis. In the practical circuit, variable capacitance diodes can be included in the resonant circuit. The dc voltage from outside can control the output of the converter.

Characteristics of high frequency gate driver by the use of LC self-excitation oscillator

The electronic circuits are miniaturized because the technique on integrated circuits has been developing. The reactance components of converters are miniaturized by using high switching frequency. The resonant converters are useful because of the low switching loss in semiconductor switches. At the resonant converters, raising or lowering output voltage is fundamentally controlled by the switching frequency. For high frequency switching in main switch, high frequency driver circuit is required. However, we have the difficult situation to obtain comparators capable of high frequency operation. Therefore, the self-excitation LC oscillation circuit is examined as the main switch drive circuit. The relatively large gate current must be poured or pulled at turn-on or turn-off. In this case, the capacitance at gate-source should be used as the component of resonant circuit. In the practical circuit, variable capacitance diodes can be included in the resonant circuit. The dc voltage from outside can control the output of the converter. In this paper, we researched about a self-excitation LC oscillation circuit by both the experiment and the simulation.