Jia You Lee

Adaptive Harmonic Control in PWM Inverters with Fluctuating Input Voltage

New techniques of harmonic reduction and voltage regulation in PWM inverters with fluctuating input voltage are described. A novel selective harmonic reduction technique is also developed for three-phase full-bridge inverters to reduce the number of switchings per output cycle. For keeping the fundamental load voltage at the present value and suppressing the generation of low-order harmonics when the input voltage fluctuates, the conventional sinusoidal reference of the triangulation method is replaced by a quasi-sinewave whose magnitude varies inversely with the input voltage to keep the product of the reference voltage and the input voltage sinusoidal. Harmonic analysis of the W-type modulation and M-type modulation is given to show that the load voltage spectra of the output waveforms generated with the proposed methods are insensitive to the source voltage fluctuation and load variation. Experimental results confirm the theoretical analysis.

A new UPS topology employing a PFC boost rectifier cascaded high-frequency tri-port converter

A new uninterruptible power supply (UPS) topology using the high-frequency tri-port UPS technique is proposed which presents the advantages of no-break power, low cost, input unity power factor, high power density, and high power conversion efficiency. Through the proposed circuit configuration, charging concept, and control strategy, the battery management is easily obtained by controlling the output voltage of the power-factor-correction (PFC) converter, which results in no additional power device being required for charging. The implementing circuit of the charging method is submitted to perform the two-stage charging, constant current charging, and constant voltage charging. The proposed technologies can be applied to the switching power supply with built-in UPS function featuring a low-cost solution for computer equipment, Finally, an experimental AC online UPS is built to verify the proposed concept, analysis, and control strategy.

Contactless inductive charging system with hysteresis loop control for small-sized household electrical appliances

In this paper, the contactless power transmission technique is investigated for inductive charging system of small-sized household electrical appliances. The application category of contactless power transmission will be briefly discussed. Different core types is analyzed and simulated for contactless power transmission to select the appropriate coupled structure for inductive charging system of small-sized household electrical appliances. Four resonant topologies and reflected impedance of inductive charging system are also analyzed and designed. Hysteresis loop control is adopted to keep the system stable by phase-locked loop (PLL). An inductive charging system of small-sized household electrical appliances is proposed and verified by the experiment which is able to charge the 600mAh lithium battery when a 2.5mm gap between small-sized household appliances and the inductive charging system is present, measuring an efficiency of 82.1%.

Study of contactless inductive charging platform with core array structure for portable products

In this research, contactless power transmission technique is applied in the charging of lithium battery for portable electronic products and the concept of common charging platform is proposed. The charging platform is comprised of several pot type cores with array structure, allowing circuit to be charged within a permitted region of displacement on the charging platform. However, a larger air gap exists in contactless structure compared to other contact structures, i.e. poor power transmission efficiency. In order to overcome the weakness, phase-locked loop (PLL) is applied to enable the operation frequency of circuit to be maintained above primary resonant frequency and microprocessor is utilized to improve the transmission efficiency when charging platform is standby. In addition, printed-circuit-board (PCB) is utilized on the secondary to reduce the thickness of the secondary circuit, forming PCB coil. Experimental results show that the transmission efficiency between contactless inductive structures is 55% under the condition of charging current 200mA and air gap 2.5mm.

A new SPWM inverter with minimum filter requirement

Abstract A new sinusoidal pulsewidth modulation (SPWM) control technique for simplifying the implementation of the SPWM method and minimizing the requirement of the voltampere rating of the inverter input filter is described and analysed. With the proposed modulation scheme, the regeneration of low-order harmonics caused by the input voltage fluctuation can be suppressed and the peak fundamental output voltage can be regulated rapidly and precisely by the dual voltage feedback control. Only a minimum voltampere rating of the inverter input filter is required for avoiding overmodulation. The theoretical results of the proposed approach with open-loop self-regulating property are discussed and experimentally verified.

Novel sinusoidal pulsewidth modulation schemes for voltage-source inverters with fluctuating input voltage

The optimum waveform parameters of pulse position and pulse widths for voltage-source inverters with fluctuating input voltage are proposed. Eight types of modulation schemes are described for synthesizing the optimum low-distortion output waveforms, of which the harmonic spectra and the peak fundamental-value are almost insensitive to the input-voltage fluctuation, with a minimum voltampere rating of inverter input filter. For fluctuating inverter input voltage with insufficient filtering, the type-VII and the alternative type-III modulation schemes are found to be especially suitable for practical implementation. Detailed descriptions of the suggested circuits with dual-feedback control for implementing two such modulation schemes are given. A peak-value detector that can rapidly produce the peak value of the inverter output voltage with a minimum time constant is also proposed. The theoretical results of the proposed approaches with one-loop self-regulating property are experimentally verified and compared with the conventional method. >

Aligned three-phase inductive coupled structure applied to contactless charging paddle system for electric vehicles

This research presents the development of a three-phase inductive coupled structure for contactless charging paddle system for electric vehicles. Several types of core shape are introduced and their magnetic circuits are simulated and analyzed. Therefore, a delta-type three-phase core structure is presented. The resonant frequency tracking control is realized in order to reduce the VA rating of primary three-phase half-bridge inverter and to achieve maximum power transfer capability to load. A prototype of the proposed contactless charging paddle system with aligned three-phase inductive coupled structure for electric vehicles is established in laboratory to confirm the functional operations and performances. Simulations and experimental results are demonstrated to show that the three-phase contact-less charging paddle system is more suitable for high power application due to the improvement of power flow smoothness between the exciting source and load.

Study and implementation of hybrid dimming inverter for T5 fluorescent lamp

In this paper, a hybrid dimming inverter for T5 fluorescent lamp is analyzable and designed. By using the digital and analog hybrid dimming, the current stress of switches is reduced, and the dimming range can be extended. A high-frequency inverter with DC 400V voltage source to drive a single T5 28W fluorescent lamp is implemented. The preheating, starting-up function, and hybrid dimming control circuit with a soft-transition operation are implemented. Also, the effectiveness of analog, digital and hybrid dimming are compared. They show that the current stress of switches is reduced by 10% at lightly load, the dimming range is 100% to 20% and the efficiency is up to 90% at full load condition.

Design and analysis of a novel soft-switched push-pull boost converter

A novel soft-switched push-pull boost converter is proposed for use as the front end converter of the uninterruptible power supply. The proposed soft-switched topologies and technologies have advantages of unity power factor, low current and low voltage stresses, small size, light weight and high efficiency. A stabilized power P/sub S/ is introduced for stabilizing the output voltage. Experimental results of the proposed soft-switched push-pull boost converter are presented for verifying the proposed topologies and the analytical methods.

Phase management control applied to two-phase interleaved half-bridge LLC resonant converter with phase-shift power factor correction

A two-phase interleaved half-bridge LLC resonant converter with phase-shift power factor correction and phase management control is presented. In order to enhance the power factor and reduce the input current ripple, two boost power factor correction converters connected in parallel with 180° phase-shift are adopted in first stage of the proposed converter and the variable output voltage control technique is also introduced to decrease the switching losses of converter. Besides, in second stage, two-phase interleaved LLC resonant converter with synchronous rectifier is applied to address the issue of output current ripple. According to different load demand, this proposed converter can automatically determine the operating mode to improve the total efficiency by the phase management control circuit. The analysis and design process of the two-phase interleaved half-bridge LLC resonant converter are shown in this paper and the validation of this concept is also demonstrated.