Chien-Ming Wang

A ZVS-PWM Single-Phase Inverter Using a Simple ZVS-PWM Commutation Cell

A new zero-voltage-switching (ZVS) pulsewidth-modulated (PWM) single-phase inverter using a simple ZVS-PWM commutation cell is presented in this paper. Except for the auxiliary switches, all switching devices in the ZVS-PWM single-phase inverter operate at ZVS turn on and turn off. The auxiliary switches operate at zero-current-switching turned-on and turned-off. Besides operating at constant frequency, the proposed inverter has no overvoltage across the switches on the main switch compared to the hard switching inverter counterpart. Auxiliary components rated at very small current are used. The principle of operation, theoretical analysis, and experimental results of the new ZVS-PWM single-phase inverter, rated 1 kW and operated at 40 kHz, are provided in this paper to verify the performance.

High-Power-Factor Soft-Switched DC Power Supply System

This paper proposes a dc power supply system to give high power factor and low current distortion on the rectifier side and provide stable dc voltage on the isolated dc/dc converter side. The proposed dc power supply system uses a new ZVS strategy to get ZVS function. Besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path, and the rectifier in the proposed dc power supply system uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. An average-current-mode control is employed in proposed dc power supply system to detect the transition time and synthesize a suitable low harmonics sinusoidal waveform for the input current. A design example of 1000 W soft-switching single-phase dc power supply system is examined to assess the converter performance.

A Novel Single-Switch Single-Stage Electronic Ballast With High Input Power Factor

This paper proposed high-power-factor electronic ballast for fluorescent lamps. The converter offers a high power factor and a high-frequency supply to the lamp using a single switch. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in phase supply current. The conventional electronic ballast circuit has larger conduction losses because its power factor correction (PFC) power flow path circuit always includes two diode losses from the front-end bridge rectifier and one power switch loss. The PFC power flow path of the proposed circuit has three conduction drops in the current flow paths when the active switch is on and two conduction drops when the active switch is off. Therefore, it can provide lower conduction loss than the conventional one. The design equations are derived from the analyzed results based on fundamental approximation, and then an easy-to-use design tool is provided accordingly under considerations of filament heating and ignition. A prototype circuit designed for one 40-W fluorescent lamps operating at 40-kHz switching frequency and 110-V line voltage is built and tested to verify the analytical predictions

A Balancing Strategy and Implementation of Current Equalizer for High Power LED Backlighting

This paper presents a current equalizer to balance the driving currents for high power LEDs (light emitting diode). The proposed strategy combined PWM strategy and digital dimming control to achieve the same illumination for each driven diodes. To obtain the same average current, the duty cycle of LEDs is modulated according to its current amplitude instead of traditional current amplitude adjusting. Complete mathematical analysis and design considerations are detailed. The experimental results are close to the theoretical predictions, and the measured tolerance errors are all below 4%.

A Novel Single-Phase Soft-Switching AC Chopper Without Auxiliary Switches

A single-phase soft-switched series-resonant ac chopper without auxiliary switches is presented. The presented single-phase ac chopper is configured by a series-resonant conversion without cycloconversion and auxiliary switches. The presented single-phase ac chopper is a series resonator with four main switches to configure adaptively the resonant voltage robes. The output sinusoidal voltage is synthesized by a series of sinusoidal amplitude quasi-sinusoidal pulses (QSPs) following the input voltage amplitude. The presented single-phase ac chopper is operated by frequency modulation with a constant-on time control. Waveform syntheses for the output sinusoidal voltage are clearly derived. A typical design example of a 600W single-phase soft-switching ac chopper is examined to assess the system performance. The power efficiency is over 92% when the output power is at maximum output rated power. The total harmonic distortion (THD) when the output power is at maximum output rated power is within 5%.

Battery management system with dual-balancing mechanism for LiFePO 4 battery module

This paper presents a battery management system of LiFePO4 battery module with dual-balancing mechanism. First, the employed battery management can accurately capture some important parameters of the LiFePO4 battery module, including voltage, current, temperature, and providing protection functions for the battery module. Next, these obtained parameters of the battery are transmitted to the microcontroller through the inter-integrated circuit (I2C-bus). And then the microcontroller can control the pack balancing circuit according to the received battery information. The proposed dual-balancing mechanism can avoid battery unbalance so as to increase the utility rate of the battery. Finally, some experimental results are used to verify the feasibility of the complete system.

A Novel Soft-Switching Single-Phase AC–DC–AC Converter Using New ZVS–PWM Strategy

This paper proposes a novel soft-switching single- phase ac-dc-ac converter to give high input power factor and low current distortion on the rectifier side and provide clean and stable ac voltage on the inverter side. The proposed converter uses a new zero voltage switching (ZVS) strategy to get ZVS function. Besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices is involved in the circulating current path, and the rectifier in the proposed converter uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. An average-current-mode control is employed in the rectifier side of proposed converter to detect the transition time and synthesize a suitable low harmonics sinusoidal waveform for the input current. The sinusoidal pulsewidth modulation (SPWM) control strategy is employed in the inverter of proposed converter to achieve good dynamic regulation. A design example of 1000 W soft-switching single-phase ac-dc-ac converter is examined to assess the converter performance.

Design of resonant backlight inverter by using primary-side control and double-ended driving

A resonant backlight inverter with double-ended driving and primary-side control are proposed to reduce the thermometer effect and leakage current effect in LCD. In this paper, the mathematical model of the lamp current including the parasitical capacitance in LCD panel is conducted to explore the influence of leakage current effect. Moreover, the primary-side control and the DPLL function are integrated to form a feedback mechanism to track the optimal operating frequency. And then the influence of parasitic capacitance can be reduced so as to eliminate the leakage current effect. Experimental results agree with the theoretical predictions.

A Novel ZVS-PWM Single-Phase Inverter Using a Voltage Clamp ZVS Boost DC Link

A novel zero-voltage-switching pulse-width-modulation (ZVS-PWM) single-phase inverter using a voltage clamp ZVS boost dc link is proposed in this paper. The proposed voltage clamp ZVS boost dc link not only provides the switches in the section of conventional PWM buck inverter operate at ZVS, but it has a boost input voltage function and the switches in itself also operate at ZVS. Thus, except for the switch in the section of ZVS-PWM commutation cell, all power semiconductor devices in proposed inverter operate at ZVS turn on and turn off. The switch in the section of ZVS-PWM commutation cell operates at zero-current-switching (ZCS) turn-on and turn-off. Besides operating at constant frequency, the proposed inverter has no voltage stress and current stress on the main switch compared to the hard switching inverter counterpart. Auxiliary components rated at very small current are used. The principle of operation, theoretical analysis, and experimental results of the new ZVS-PWM single-phase inverter, rated 1kW and operated at 80 kHz, are provided in this paper to verify the performance.

Design and implementation of a bi-directional power converter for electric bike with charging feature

This paper presents a bi-directional converter applied in electric bike. The main structure is a cascade buck-boost converter, which transfers the energy stored in battery for driving motor, and can recycle the energy resulted from the back electromotive force (BEMF) to charge battery by changing the operation mode. Moreover, the proposed converter can also serve as a charger by connecting with AC line directly. Besides, the single-chip DSP TMS320F2812 is adopted as a control core to manage the switching behaviors of each mode and to detect the battery capacity. In this paper, the equivalent models of each mode and complete design considerations are all detailed. All the experimental results are used to demonstrate the feasibility.