Khairy Fathy

Boost-Half Bridge Single Power Stage PWM DC-DC Converter for Small Scale Fuel Cell Stack

This paper presents the implementation of 1 kW prototype high frequency link boost half bridge inverter-fed DC-DC power converter with bridge voltage-doublers suitable for small scale PEM fuel cell system and its associated control scheme. The operation principle of this converter is described using fuel cell modeling and some operating waveforms and the switching mode equivalent circuits based on simulation results and a detailed circuit operation analysis and soft-switching conditions.

Three-Level Phase Shifted soft transition PWM DCDC power converter with high frequency link for arc welders and its extended version

This paper presents some experimental results and practical evaluations of neutral point clamping and flying capacitor hybrid three-level phase shifted soft switching PWM DC-DC high power converter with high frequency transformer and center-tapped rectifier. This new DC-DC converter developed for TIG, MIG and MAG arc welders is implemented by modifying the high-frequency-linked HB soft switching PWM DC-DC power converter with high side and low side two active edge resonant modular, which is proposed by the authors. The operating principle of the three-level soft-switching PWM DC-DC converter and its experimental and simulation results including phase-shifted angle vs. power regulation characteristics and power conversion efficiency characteristics in addition to power loss analysis are illustrated and discussed from a practical point of view, along with the remarkable advantageous points as compared with previously-developed soft switching PWM DC-DC converter. Finally, the improved three-level soft switching PWM converter version is also considered to suppress the circulating current due to phase shift pulse modulation principle. The PWM and PDM dual pulse modulation strategy is considered to extend its soft switching transition operation range.

A Novel Soft-Switching PWM Full-Bridge DC/DC Converter with DC Busline Series Switch-Parallel Capacitor Edge Resonant Snubber Assisted by High-Frequency Transformer Leakage Inductor

This paper presents two new circuit topologies of DC busline side active edge resonant snubber assisted soft-switching PWM high frequency AC link full-bridge DC-DC converter acceptable for 200V-rms and 400V-rms utility AC mains. All the power switches in the full-bridge arms and DC busline can turns on with ZCS turn-on and turn-off with ZVS and the switching power losses of all the switches can be reduced for high-frequency switching PWM. Each operating principle of the proposed soft-switching PWM DC-DC converter with a high frequency planner transformer link is described, together with the experimental performances

A Divided Voltage Half-Bridge High Frequency Soft-Switching PWM DC-DC Converter with High and Low Side DC Rail Active Edge Resonant Snubbers

This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices for PWM control scheme and capacitive lossless snubbers. All the active power switches in the half-bridge arm and dc bus lines can achieve ZCS turn-on and ZVS turn-off commutation operation and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency of using IGBTs can be actually selected more than about 20 kHz

A New Soft-Switching PWM Half-Bridge DC-DC Converter with High and Low Side DC Rail Active Edge Resonant Snubbers

This paper presents a new circuit topology of dc bus line switch-assisted half-bridge soft switching PWM inverter type dc-dc converter for arc welder. The proposed power converter is composed of typical voltage source half-bridge high frequency PWM inverter with a high frequency transformer link in addition to dc bus line side power semiconductor switching devices for PWM control scheme and capacitive lossless snubbers. All the active power switches in the half-bridge arm and dc bus lines can achieve ZCS turn-on and ZVS turn-off commutation operation and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency of using IGBTs can be actually selected more than about 20 kHz. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies such as arc welder from a practical point of view.

An Asymmetrical Switched Capacitor and Lossless Inductor Quasi-Resonant Snubber-Assisted ZCS-PWM DC-DC Converter with High frequency Link

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM resonant DC-DC converter with two auxiliary edge resonant lossless inductor snubbers. The operation principle of this converter is described using the switching mode equivalent circuits. This newly developed multi resonant DC-DC converter can regulate its dc output AC power under a principle of constant frequency edge-resonant soft switching commutation by asymmetrical PWM control scheme. The high frequency power regulation and actual power conversion efficiency characteristics of the proposed soft switching PWM series load resonant DC-DC converter are evaluated. The operating performances of the newly proposed soft switching inverter are discussed based on simulation results from an application point of view

PWM/PDM dual mode controlled soft switching multi resonant high-frequency inverter

In this paper, a novel type auxiliary active resonant capacitor snubber assisted zero current soft switching pulse modulation single-ended push pull (SEPP) series load resonant inverter with two auxiliary resonant lossless inductor snubbers is proposed for consumer high-frequency induction heating (IH) appliances. Its operating principle in steady state is described by using each mode equivalent circuits. The new multi resonant high-frequency inverter can regulate its output power under a condition of a constant frequency zero current soft switching (ZCS) commutation principle on the basis of asymmetrical PWM control scheme. The consumer brand-new IH products using proposed ZCS-PWM series load resonant SEPP high-frequency inverter is evaluated and discussed as compared with conventional high-frequency inverter on the basis of experimental results. In order to extend ZCS operation ranges under a low power setting PWM, the pulse density modulation (PDM) strategy is demonstrated for high frequency multi resonant inverter. Its practical effectiveness is substantially proved from an application point of view

32 V-300 A/60 kHz edge resonant soft-switching PWM DC/DC converter with DC rail series switch-parallel capacitor snubber assisted by high-frequency transformer parasitic components

The conduction losses of the active switches can be lowered, which are connected to the primary side of extremely step-down high frequency transformer because of low voltage large current rectifier configuration. This paper presents two new circuit topologies of DC busline side active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200 V-rms or AC 400 V-rms input voltage source. One topology of proposed DC-DC converters is composed of a typical voltage source-fed full-bridge high frequency PWM inverter using DC busline side series power semiconductor switching devices with the aid of a parallel capacitive lossless snubber. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. It is proved that the more the switching frequency of full-bridge soft switching inverter increases, the more soft-switching PWM DC-DC converter with a high frequency transformer link has remarkable advantages for its efficiency and power density as compared with the conventional hard-switching PWM inverter type DC-DC converter. In this paper, another modified version topology of utility AC 200 V-rms grid-connected soft switching DC-DC converter mentioned above is also implemented and evaluated, which is more suitable for utility 400 V-rms grid power source. The effectiveness of these new DC-DC converters topologies is proved for low voltage and large current high efficiency DC-DC power supplies as TIG are welding machine from a practical point of view.

A Utility AC 400V Grid-Connected DC Rail Side Active Edge Resonant ZVS-PWM DC-DC Converter using High-Frequency Transformer Parasitic Components

This paper presents two new circuit topologies of voltage source-fed soft-switching PWM inverter using a high frequency transformer parasitic inductive components with full- bridge or half-bridge configuration, which are more suitable for utility AC 400 V-rms input mains. These circuits have each reverse conducting power semiconductor switching devices in series with high and low DC buslines, a single or two lossless snubbing capacitors in parallel with two DC buslines and additional diode components. Under the newly proposed high frequency softswitching PWM inverter link DC-DC power converter circuits for utility AC 400V-rms input, all the active power switches in the full- bridge arms or half-bridge arm and DC buslines achieve ZCS turn- on commutation operation and ZVS turn-off commutation operation, and consequently the total turn-off switching power losses can be significantly reduced. As a result, a high switching frequency for IGBTs used can be actually realized at a frequency band more than about 20 kHz. It is proved that the more the switching frequency of inverter increases, the more soft switching PWM DC-DC converters with a high frequency transformer have remarkable advantages for its power conversion efficiency and power density as compared with the conventional hard switching PWM full-bridge inverter type DC-DC converter. The practical effectiveness of these new converter topologies are confirmed for low voltage and large current DC power supplies as high performance arc welding machine from a practical point of view.

A New High Frequency Linked Soft-Switching PWM DC-DC Converter with High and Low Side DC Rail Active Edge Resonant Snubbers for High Performance Arc Welder

This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type dc-dc high power converter for DC bus feeding power plants. The proposed dc-dc power converter is composed of typical voltage source fed half-bridge high frequency PWM inverter with a high frequency transformer planar link in addition to dc busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new dc-dc converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and dc buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions and consequently the total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the range of 60 kHz under the principle of soft switching. The performance evaluations of the setup are illustrated experimentally. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies such as DC bus feeding from a practical point of view