Huann-Keng Chiang

Analysis, design and implementation of an active clamp flyback converter

This paper presents the detailed circuit operation, mathematical analysis, and design example of the active clamp flyback converter. The auxiliary switch and clamp capacitor are used in the flyback converter to recycle the energy stored in the transformer leakage in order to minimize the spike voltage at the transformer primary side. Therefore the voltage stress of main switch can be reduced. The active clamped circuit can also help the main switch to turn on at ZVS using the switch output capacitor and transformer leakage inductance. First the circuit operation and mathematical analysis are provided. The design example of active clamp flyback converter is also presented. Finally the experimental results based on a 120 W prototype circuit are provided to verify the system performance

Hybrid Active Power Filter for power quality compensation

This paper presents a hybrid active power filter to achieve power quality compensation. There is a passive filter and an active power filter in the adopted system. The passive power filter is used to filter the low order harmonic current with large power rating. The active power filter with low power rating is used to filter the other high order harmonics. Therefore the cost of hybrid active power filter is much lower than shunt active power filter. The neutral point diode clamped inverter is operated as an active power filter to achieve compensated current tracking. A dc-link voltage controller and a phase locked loop circuit are used in the system to generate the reference line currents. The hysteresis comparators are adopted to track current commands. Experimental results based on a laboratory prototype are provided to verify the effectiveness of the control scheme.

Analysis and Implementation of a ZVS-PWM Converter With Series-Connected Transformers

This brief presents the analysis, design, and implementation of zero-voltage switching (ZVS) active clamp converter with series-connected transformer. A family of isolated ZVS active clamp converters is introduced. The technique of the adopted ZVS commutation will not increase additional voltage stress of switching devices. In the adopted converter with series-connected transformer, each transformer can be operated as an inductor or a transformer. Therefore, no output inductor is needed. To reduce the voltage stress of the switching device in the conventional forward converter, the active clamp technique is used to recycle the energy stored in the transformer leakage back into the input dc source. Finally, experimental results are presented taken from a laboratory prototype with 100-W rated power, input voltage of 155 V, output voltage of 5 V, and operating at 150 kHz.

Analysis and implementation of a bidirectional ZVS dc-dc converter with active clamp

A bidirectional ZVS DC-DC converter with active clamp topology is proposed. The proposed converter is based on the forward converter with center-tapped rectifier at the transformer secondary side. Active clamp topology is used in the forward converter to achieve ZVS feature of power switches and to regulate the output voltage at the desired value. The proposed converter has the advantages of high efficiency and simple circuit configuration. The operating principle, system analysis and design example are described and discussed in detail. Finally, the experimental results of the proposed converter are provided to verify the theoretical analysis.

Design and Implementation of a Sliding Mode Controller Using a Gaussian Radial Basis Function Neural Network Estimator for a Synchronous Reluctance Motor Speed Drive

Abstract This article presents a sliding mode control using a Gaussian radial basis function neural network speed control design for robust stabilization and disturbance rejection of the synchronous reluctance motor. In the conventional sliding mode control design, it is assumed that the upper boundary of parameter variations and external disturbances is known and the sign function is used. This causes high-frequency chattering and high gain. A new sliding mode controller using a Gaussian radial basis function neural network estimator is proposed for the synchronous reluctance motor. The proposed method utilizes the Lyapunov function candidate to guarantee convergence and to track the speed command of the synchronous reluctance motor asymptotically. The estimator of parameter variations and external disturbances is designed to estimate the lump unknown uncertainty value in real time. Experiments were conducted to validate the proposed method.

Analysis, Design and Implementation of an Active Clamp Forward Converter with Synchronous Rectifier

The system analysis, circuit design, and implementation of active clamp based forward converter with synchronous rectifier are presented in this paper. To release the energy stored in the leakage inductor and to minimize the spike voltage at the transformer primary side, active clamp circuit included one clamp switch and one clamp capacitor is adopted in the circuit. Based on the partial resonance with the output capacitor of switch and the leakage inductor of transformer, the main switch is turned on at zero voltage switching (ZVS). The clamp switch is also operated at ZVS operation based on the resonance of leakage inductor and clamp capacitor. The synchronous switches are used at the secondary side to further reduce the conduction losses. The experimental results based on the laboratory prototypes are presented to verify the circuit performance

Implementation of an interleaved ZVS boost-type converter

An interleaved zero voltage switching (ZVS) converter with less component count and boost voltage conversion ratio is presented. The output voltage doubler is used on the output side to achieve the boost type of voltage conversion ratio. The proposed converter includes two active-clamping converters with common clamp capacitor to share load current. By the shared capacitor, the charge balance of two interleaved parts is automatically regulated under input voltage and load variations. The ZVS turn-on of all switching devices is achieved during the transition interval. The interleaved pulse-width modulation (PWM) operation will reduce the ripple current and the size of the output capacitor. The proposed circuit has no large output inductor such that the adopted circuit has simpler structure, lower cost and no effective duty loss. The voltage stresses on output diodes are clamped at the output voltage. The circuit configuration, operation principles and design consideration are presented. Finally experimental results based on a 425W (170V/2.5A) prototype are provided to verify the effectiveness of the proposed converter.

Analysis of a new ZVS converter with output voltage doubler

A novel zero voltage switching (ZVS) converter with output voltage doubler is presented. The output voltage doubler is used on the output side to achieve the boost type of voltage conversion ratio. Active-clamping technique is adopted to realize the ZVS turn-on of all switches, release the energy stored in the transformer leakage inductance and limit the voltage stresses on power switches. The ZVS function is achieved at the commutation stage of two complementary switches. The proposed circuit has no large output inductor such that the adopted circuit has simpler structure, lower cost and no effective duty loss. The voltage stresses on output diodes are clamped at the output voltage. The circuit configuration, operation principles and design consideration are presented. Finally experimental results based on a 300W prototype are provided to verify the effectiveness of the proposed converter.

Super-twisting second-order sliding mode control for a synchronous reluctance motor

This article presents the design and implementation of a super-twisting second-order sliding-mode controller (SOSMC) for a synchronous reluctance motor. Second-order sliding-mode control is an effective tool for the control of uncertain nonlinear systems since it overcomes the main drawbacks of the classical sliding-mode control, i.e., the large control effort and the chattering phenomenon. Its real implementation implies simple control laws, and ensures an improvement in the sliding accuracy with respect to conventional sliding-mode control. This article proposes a novel scheme that is based on the technique of super-twisting second-order sliding-mode control. First, SOSMC is derived mathematically, and then the performance of the proposed method is verified by simulations. The proposed SOSMC shows robustness for variations in the motor parameters and an improvement in the chattering phenomenon.

Active-clamping dual resonant converter

A dual resonant converter using active clamp circuit is presented in this paper. The active clamp circuit is employed to limit the voltage stress and create zero-voltage-switching (ZVS) turn-on feature for power switches. Moreover, the dual resonant tanks are composed by the leakage inductors and resonant capacitors to achieve zero-current-switching (ZCS) turn-off mechanism for diodes at the secondary side of transformer. Hence, the reverse-recovery problem can be eliminated. The operational principles, design consideration and realization are discussed. Finally, experimental results from a 400W prototype are presented to confirm the effectiveness of the proposed converter.