Jinbin Zhao

Steady-state and dynamic analysis of a buck converter using a hysteretic PWM control

In this paper, steady state and dynamic analysis of a buck converter using a hysteretic PWM control scheme is presented. Since the proposed control scheme only uses a comparator with hysteresis and a feedback resistor, numbers of components in a control circuit are reduced. In addition, no error amplifier is used, thus the stability of the converter becomes excellent. The steady state and dynamic analysis of the proposed converter is performed and verified by experiments. We proved that the proposed control scheme has no phase lag and shows excellent transient response.

A new PWM control scheme using a triangle waveform modulated by output voltage

In this paper, a new PWM control scheme using a triangle waveform modulated by output voltage is presented. Since the proposed control scheme only uses a comparator with hysteresis and a feedback resistor, numbers of components in a control circuit are reduced. In addition, because no error amplifier is used, the stability of the converter becomes excellent. The steady-state analysis of the proposed converter is performed and verified by the experiments.

Grid-connected inverter with inner output impedance and governor-free characteristics

This paper proposes for a PWM ac/dc inverter a new control algorithm that provides the inverter with both inner output impedance and governor-free characteristics. The proposed algorithm regulates the inverter as a voltage source all the time in not only standalone but grid-connected operations. The Parks equation of a synchronous machine is realized in a PWM inverter. The inner output impedance and the governor-free characteristics based on the algorithm are analyzed mathematically. The characteristic equations to design the inverter are derived through the analysis. Experimental results show that the measured values and the calculated values get in good agreement. The output voltage and current performance of the proposed inverter is characterized similarly to a synchronous machine without any compulsory control.

An improved interleaved forward converter

Operations and steady-state analysis for an improved interleaved forward converter topology are presented in this paper. Not only Zero-voltage-switching (ZVS) can be achieved through the resonance that exists between the transformers magnetizing inductances and the parasitic capacitance of switches, but also proper transformer reset and lower output voltage can be achieved by adding two clamp capacitors, such as topology of the proposed converter become simplest possible. Finally, the results of the analysis are verified by experimental and simulation. By using the proposed topology, the voltage stresses across the switches are limited to the input voltage. The voltage stresses across the switches are greatly lower than the converters with active-clamp circuit, and compared to conventional interleaved forward converter, using same duty, lower output voltage can be obtained.

A novel two-switch forward converter for high step-down conversion

In this paper, a novel two-switch forward converter topology for high step-down conversion is proposed. Comparing with the conventional two-switch forward converter, it uses two series inductors L1 and L2 to extend the duty cycle, and achieve the lower output voltage. In order to prove above results, detailed steady-state analysis is presented, and an input voltage 400V, output voltage 1.5V, output current 50A prototype converter was built. Finally, simulation results verify the theoretical analysis and show the significant advantages.