Hung-Shiang Chuang

Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive LEDs for Lighting Applications

White light emitting diode (LED) with high brightness has attracted a lot of attention from both industry and academia for its high efficiency, ease to drive, environmental friendliness, and long lifespan. They become possible applications to replace the incandescent bulbs and fluorescent lamps in residential, industrial and commercial lighting. The realization of this new lighting source requires both tight LED voltage regulation and high power factor as well. This paper proposed a single-stage flyback converter for the LED lighting applications and input power factor correction. A type-II compensator has been inserted in the voltage loop providing sufficient bandwidth and stable phase margin. The flyback converter is controlled with voltage mode pulse width modulation (PWM) and run in discontinuous conduction mode (DCM) so that the inductor current follows the rectified input voltage, resulting in high power factor. A prototype topology of closed-loop, single-stage flyback converter for LED driver circuit designed for an 18W LED lighting source is constructed and tested to verify the theoretical predictions. The measured performance of the LED lighting fixture can achieve a high power factor greater than 0.998 and a low total harmonic distortion less than 5.0%. Experimental results show the functionality of the overall system and prove it to be an effective solution for the new lighting applications.

Implementation and Analysis of an Improved Series-Loaded Resonant DC–DC Converter Operating Above Resonance for Battery Chargers

The well-established advantages of resonant converters, including simplicity of circuit configuration, ease of the control scheme, low switching losses, and low electromagnetic interference, among others, have led to their attracting more interest. This work develops a highly efficient battery charger with an improved series-loaded resonant converter for renewable energy applications to improve the performance of traditional switching-mode charger circuits. The switching frequency of the improved series-loaded resonant battery charger was at continuous conduction mode. Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. This study utilizes the fundamental wave approximation and a battery equivalent circuit to simplify the circuit analyses. The mean charging efficiency of the proposed topology is as high as 87.5%.

Analysis and implementation of half-bridge series-parallel resonant converter for battery chargers

This paper presents a novel application of half-bridge series-parallel resonant converter (HBSPRC) for dc source and secondary battery interface. The converter practically eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger circuit. Moreover, operation above resonance is preferred because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. The proposed battery charger circuit has few components and low energy conversion loss, which enhance the systems overall efficiency. Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. Experimental results based on a 12V 48Ah battery charger are proposed to validate the analysis and to demonstrate the performance of the proposed approach. The maximum charging efficiency of the proposed topology during the overall charging period is 93.98%. Satisfactory performance is obtained from the measured results.

Implementation and analysis of an improved series-loaded resonant dc-dc converter operating above resonance for battery chargers

The well established advantages of resonant converters, including simplicity of circuit configuration, easy of the control scheme, low switching losses, and low electromagnetic interference (EMI), among others, have led to their attracting more interest. This work develops a highly efficient battery charger with an improved series-loaded resonant converter for renewable energy applications to improve the performance of traditional switching-mode charger circuits. The switching frequency of the improved series-loaded resonant battery charger was at continuous conduction mode (CCM). Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. This study utilizes the fundamental wave approximation and a battery equivalent circuit to simplify the circuit analyses. The mean charging efficiency of the proposed topology is as high as 87.5%.

Analysis of commutation torque ripple using different PWM modes in BLDC motors

Torque ripple generated in the commutation interval is one of the main drawbacks of Brushless DC (BLDC) motors. This paper presents an comprehensive analysis on the generated torque ripples of trapezoidal back-EMF due to phase commutation in the six switch, three-phase inverter brushless dc motor drives. Experimental results verify the amplitude of the torque ripple under 4 kinds of PWM pattern, respectively.

A novel single-switch resonant power converter for renewable energy generation applications

This paper develops a novel single-switch resonant power converter for renewable energy generation applications. This circuit topology integrates a novel single-switch resonant inverter with zero-voltage switching (ZVS) with an energy-blocking diode with zero-current switching (ZCS). The energy-blocking diode with a direct-current output filter filters the output stage of the novel single-switch resonant inverter. Only one active power switch is used for power energy conversion to reduce the cost of active power switches and control circuits. The active power switch is controlled by pulsewidth modulation at a fixed switching frequency and a constant duty cycle. When the resonant converter is operated at discontinuous conduction mode, the inductor current through the resonant tank could achieve ZCS of the energy-blocking diode. Accordingly, a high energy conversion efficiency is ensured. Operating principles are derived, and analyses are carried out based on the equivalent circuits for the proposed power converter under different operating modes. The operating principles of the converter were verified using a 32.4-W 70-kHz experimental photovoltaic-powered load system. Given appropriately chosen circuit parameters, the active power switch can be operated with ZVS, and a measured energy conversion efficiency of the proposed topology of 97.3% can be achieved. Experimental results demonstrate a satisfactory performance of the proposed topology, which is particularly suited to the energy conversion applications in renewable energy generation systems.

Battery float charge technique using parallel-loaded resonant converter for discontinuous conduction operation

This paper presents a battery float charge technique based on a parallel-loaded resonant converter. The main purpose of the float charge is to ensure that the battery remains fully charged indefinitely. With a simple circuit configuration and few components, low switching loss and high efficiency are achieved. The proposed parallel-loaded resonant converter is operated in discontinuous current mode to achieve high efficiency at a fixed switching frequency. With carefully designed circuit parameters, the power switches can support zero voltage switching and zero current switching. The operating principles and equivalent circuit are analyzed in detail. Experimental results are obtained using a 12-V 150-Ah rechargeable battery to confirm the feasibility of the proposed scheme. The maximum charging efficiency of the proposed topology during the overall float charge period is 97.6%. The measurements yield satisfactory performance.

A Novel Loaded-Resonant Converter for the Application of DC-to-DC Energy Conversions

Among the many advantages that resonant power conversion has over conventionally adopted PWM include a low electromagnetic interference, low switching losses, small volume and light weight of components due to a high switching frequency, high efficiency, and low reverse-recovery losses in diodes owing to a low di/dt at switching instant. This work presents a novel loaded-resonant converter for DC-to-DC energy conversion applications. The proposed topology comprises a half-bridge LC-L resonant inverter and a bridge rectifier. Output stage of the proposed loaded-resonant converter is filtered by a low-pass filter. A prototype DC-to-DC energy converter circuit with the novel loaded-resonant converter designed for a load is developed and tested to verify its analytical predictions. The measured energy conversion efficiency of the proposed novel loaded-resonant topology reaches up to 88.3%. Moreover, test results demonstrate a satisfactory performance of the proposed topology. Furthermore, the proposed topology is highly promising for applications of power electronic productions such as switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies.

Highly efficient ZCS boost converter used in rechargeable batteries

This work develops a highly efficient zero-current-switching (ZCS) boost converter used in rechargeable batteries. An auxiliary power switch in series with the resonant tank enables the semiconductor devices in the charger circuit are to be turned on and off by soft switching. The developed charger topology practically eliminates the charging current ripple in the battery, maximizing battery life without increasing the volume of the converter. Therefore, a battery charger with the proposed ZCS boost converter can be operated with low switching power losses. No additional voltage or current stresses are caused on the auxiliary switch or auxiliary diode. Additionally, the proposed ZCS boost converter for rechargeable batteries has a simple structure, low cost, light weight, ease of control, and high efficiency. The operating principles and design procedure are analyzed and discussed in detail. The optimal values of the pertinent properties of the resonant components are determined from the characteristic curve and the electric functions that are obtained from the circuit configuration. Simulation results and experimental results obtained using a laboratory prototype demonstrates the feasibility of the proposed topology. Finally, a prototype circuit that is designed for a 24V-50Ah lead-acid battery bank is built and tested to confirm the theoretical predictions. The maximum charging efficiency of the proposed topology throughout the overall charging period is 95.8%. Experimental results reveal the satisfactory performance of the proposed topology, which is especially suitable for battery charging applications.

A novel battery charger circuit with an improved parallel-loaded resonant converter for rechargeable batteries in mobile power applications

This work proposes a novel battery charger circuit with an improved parallel-loaded resonant converter use in rechargeable batteries in mobile power applications. The proposed topology is composed of an improved parallel-loaded resonant inverter and a bridge rectifier. The output voltage of the improved parallel-loaded resonant converter is filtered by an electrolytic capacitor. This topology has advantages over the traditional parallel-loaded resonant converter of smaller size, lower weight and lower cost. The operating principles of the proposed charger circuit are thoroughly analyzed. A prototype charger circuit with the improved parallel-loaded resonant converter implemented for a 12V 12000mAh rechargeable battery of mobile power is constructed and tested to verify the theoretical predictions. The measured energy conversion efficiency of the improved parallel-loaded resonant topology reaches up to 91.2%. The test results demonstrate that the novel topology provides a satisfactory performance. The improved parallel-loaded resonant converter has great potential for use in power-related devices in electronic products, such as standby power supplies for laptop computers, communication equipment, consumer electronics, and telecom power supplies.