Sinewave PWM Research Articles

Utility AC interfaced soft-switching sinewave PWM power conditioner with two-switch flyback high-frequency transformer

High-frequency switching pulse modulation utility-interfaced power conditioners (HF-UPC) with a high-frequency transformer link have attracted special interest for renewable and sustainable energy utilisation. These conditioners are small and cost-effective for meeting the requirements of small-scale residential power applications. However, switching power losses due to high-frequency switching operations are unavoidable. Efforts to reduce the power losses by implementing additional snubber components can complicate the controlling methods of the system. To solve these problems, a flyback transformer linked HF-UPC is proposed. The high-frequency flyback transformer is introduced into the power conditioner system instead of the typical forward transformer to simplify the circuit configuration and related controlling methods. With the aid of the resonant snubber circuits, the high-frequency switching devices in the primary side of the proposed DC-to-AC power conditioner can be turned off with zero-voltage soft-switching (ZVS). In addition, the proposed power conditioner system takes advantage of operating the currents by the discontinuous conduction mode (DCM) to realise turn-on commutation of zero-current soft-switching schemes. The output ports of the HF-UPC treated here are directly connected to the utility grid single-phase AC power source. A prototype of the proposed soft-commutation HF-UPC has been built and tested in experiments. Its power conversion processing is verified and its output current is qualified in accordance with the guidelines of the power utility companies.

Effective Improvement of DC Busline Voltage Utilization Factor in Two Switch-Auxiliary Quasi-Resonant DC Link Snubber Assisted Three Phase Voltage Source Type Soft-Switching PWM Inverter

In recent years, a resonant snubber to minimize switching power losses and EMI noises have attracted special interest for the voltage-fed soft switching sinewave PWM inverters and active rectifiers. The authors have discussed the performance evaluations on lower noise and high efficiency for two switch auxiliary resonant DC link snubber assisted three-phase voltage-fed soft switching PWM inverter. It was proved that cost effective three phase soft switching inverter treated here is able to improve both efficiency and EMI noise. However, some practical problems to be improved have recognized for the soft-switching three phase PWM inverter treated here from a practical point of view. This three phase soft-switching inverter with two switch type auxiliary resonant DC link snubber has significant disadvantages of DC busline link voltage reduction for the existence of the zero voltage mode transition period as well as the larger size and physical volume of electrolytic capacitor incorporated into the resonant DC link snubber. The additional technology to minimize the busline DC link zero voltage period in order to overcome the practical problems mentioned above is newly proposed in this paper. From experimental and simulation viewpoints, the modified version of this soft-switching inverter is discussed and evaluated for the DC busline voltage utilization factor as compared with the previously developed one.

系統連系高周波2石フライバックトランス絶縁方式ソフトスイッチングPWM正弦波インバータ

This paper presents two novel prototypes of the utility AC power source connected sinewave inverter using the high-frequency two-switch flyback transformer which is more suitable and acceptable for the small-scale solar photovoltaic and fuel cell generator interfaced power conditioners. The proposed sinewave soft-switching PWM power conditioner with a high-frequency AC link has a function of electrical isolation including sinewave hard-switching PWM power conditioner with a high frequency link, which is considered for solar photovoltaic power conditioner and fuel cell generator related power conditioner from the viewpoints of safety and reliability in total system. The discontinuous conduction mode (DCM) operation of the flyback transformer in this circuit system is also introduced to feature a simple, low-cost and high-efficiency topology of the sinewave inverter circuit and digital control implementation. The operating principle of the proposed sinewave soft-switching PWM inverter circuit as compared with sinewave hard-switching PWM inverter are described for the designing of circuit parameters. Moreover, the digitally controlled sinewave PWM control processing scheme is presented herein. Finally, the sinewave soft-switching PWM inverter prototype is actually built and tested to verify the validity of the proposed power conditioner for new energy generation systems.

新ゲートパターンアクティブ補助共振スナバソフトスイッチングインバータの検討

This paper presents a new topology of the voltage source type bridge soft switching inverter circuit which proposes a novel active edge resonant snubber circuits using the auxiliary power switches. This advanced inverter is more suitable and acceptable for an uninterruptible power supply, such as PFC power converter, utility-interactive bi-directional power converter and new energy related distributed power supplies. The soft switching operation principle and design procedure of the active auxiliary edge resonant snubber circuit are described and discussed for the high power applications. Both the main active power switches and the auxiliary power switches achieve ZVS or ZCS for sinewave PWM inverter. This inverter does not need any sensor interfaced circuit to detect the voltage or the current and does not also required for the electrolytic chemical capacitors to make the neutral point of the DC power supply voltage side. This paper proposes a new gate timing pattern of switches in this soft switching inverter circuit, too. This method can limit the current of the active edge resonant snubber circuits lower than a level of the load current. As a result, the total efficiency characteristics of the converter system is improved high in all load range.

Current-fed three-phase and voltage-fed three-phase active converters with optimum PWM pattern scheme and their performance evaluations

This paper describes a new approach to select the optimum sinewave pulsewidth modulation (PWM) patterns suitable for a large-capacity current-fed active PWM power converter and a practical design procedure to determine circuit constants of a low-pass filter connected to suppress higher line current harmonics flowing into the utility-grid AC power source. A feasible test is implemented by building a prototype 500 kW three-phase current-fed PWM power converter which is designed and controlled on the basis of the proposed considerations. It is verified from a practical point of view that these new conceptual considerations are more effective and acceptable to minimize higher harmonic current components flowing into the utility-grid AC power source. This experimental setup provides highly efficient steady-state characteristics of the current-fed three-phase PWM power converter under the operating condition of a unity power factor correction and sinewave line current shaping schemes. Furthermore, this unique optimum PWM pattern derived from the theoretical method proposed here is conveniently applicable to a voltage-fed three-phase PWM converter. It is verified that this optimum PWM pattern provides excellent switching performance with a lower switching frequency mode than the conventional carrier-based PWM scheme.

High Efficiency Controlled Interior Permanent Magnet Synchronous Motor for Air conditioner fed by Sine-wave PWM Inverter

High Efficiency Controlled Interior Permanent Magnet Synchronous Motor for Air conditioner fed by Sine-wave PWM Inverter

Current-fed three-phase converter with optimum PWM scheme and its practical input line filter design

A method is described of selecting the optimum sine wave PWM patterns of a large-capacity current source-fed three-phase active PWM converter. Its performance evaluations are also described. A practical procedure is presented of designing a low-pass filter connected to suppress higher line current harmonics flowing into the utility-grid power source. A feasibility test is performed by using a 500 kVA three-phase active current-fed PWM converter, which has been modified. It is verified, from a practical point of view, that such conceptual considerations are more effective and acceptable in minimising higher harmonic current components flowing into the utility-grid AC power line. Furthermore, this experimental set-up provides highly efficient AC/DC PWM-PFC converter characteristics, under the operating condition of a unity power factor correction and sine wave line current shaping schemes.

An Expert System for Real-Time Control of a Multi-Terminal Direct Current Transmission System

This paper presents a real-time expert system (RTES) for on-line monitoring and control of a Multi-terminal direct Current Transmission (MTDC) system. The expert system comprises of a two level black board architecture. This is implemented on a four node transputer-based multiprocessing system along with an intelligent high speed data acquisition system (IDAS). The dc converters considered in this paper are based on sinewave pulse width modulation (SPWM) technology. In this case the triggering strategy is more complex, but the resulting system control yields a number of advantages which cannot be realized otherwise. A novel firing pulse generator (FPG) hardware with suitable inter face to the IDAS makes it possible to perform this task in real-time.