Michael Joseph Schutten

Characteristics of load resonant converters operated in a high-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained. >

Industrial applications of fuzzy logic at General Electric

Fuzzy logic control (FLC) technology has drastically reduced the development time and deployment cost for the synthesis of nonlinear controllers for dynamic systems. As a result we have experienced an increased number of FLC applications. We illustrate some of our efforts in FLC technology transfer, covering projects in turboshaft aircraft engine control, steam turbine startup, steam turbine cycling optimization, resonant converter power supply control, and data-induced modeling of the nonlinear relationship between process variables in a rolling mill stand. We compare these applications in a cost/complexity framework, and examine the driving factors that led to the use of FLCs in each application. We emphasize the role of fuzzy logic in developing supervisory controllers and in maintaining explicit tradeoff criteria used to manage multiple control strategies. Finally, we describe some of our FLC technology research efforts in automatic rule base tuning and generation, leading to a suite of programs for reinforcement learning, supervised learning, genetic algorithms, steepest descent algorithms, and rule clustering. >

10 kV, 120 A SiC half H-bridge power MOSFET modules suitable for high frequency, medium voltage applications

The majority carrier domain of power semiconductor devices has been extended to 10 kV with the advent of SiC MOSFETs and Schottky diodes. The devices exhibit excellent static and dynamic properties with encouraging preliminary reliability. Twenty-four MOSFETs and twelve Schottky diodes have been assembled in a 10 kV half H-bridge power module to increase the current handling capability to 120 A per switch without compromising the die-level characteristics. For the first time, a custom designed system (13.8 kV to 465/√3 V solid state power substation) has been successfully demonstrated with these state of the art SiC modules up to 855 kVA operation and 97% efficiency. Soft-switching at 20 kHz, the SiC enabled SSPS represents a 70% reduction in weight and 50% reduction in size when compared to a 60 Hz conventional, analog transformer.

Characteristics of load resonant converters operated in a high power factor mode

The performance of the parallel resonant converter and the combination series/parallel resonant converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single-phase applications. When the DC voltage applied to the input of these converters is obtained from a single-phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behaviour is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near unity power factor and low input harmonic currents can be obtained.<<ETX>>

10 kV/120 A SiC DMOSFET half H-bridge power modules for 1 MVA solid state power substation

In this paper, the extension of SiC power technology to higher voltage 10 kV/10 A SiC DMOSFETs and SiC JBS diodes is discussed. A new 10 kV/120 A SiC power module using these 10 kV SiC devices is also described which enables a compact 13.8 kV to 465/√3 solid state power substation (SSPS) rated at 1 MVA.

Ripple current cancellation circuit

A ripple current cancellation technique injects AC current into the output voltage bus of a converter that is equal and opposite to the normal converter ripple current. The output current ripple is ideally zero, leading to ultra-low noise converter output voltages. The circuit requires few additional components, no active circuits are required. Only an additional filter inductor winding, an auxiliary inductor, and small capacitor are required. The circuit utilizes leakage inductance of the modified filter inductor as all or part of the required auxiliary inductance. Ripple cancellation is independent of switching frequency, duty cycle, and other converter parameters. The circuit eliminates ripple current in both continuous conduction mode and discontinuous conduction mode. Experimental results provide better than an 80/spl times/ ripple current reduction.

Auxiliary series resonant converter: a new converter for high-voltage, high-power applications

The power converter presented in this paper has been designed to meet high-quality power requirements in high-voltage, high-power applications such as X-ray imaging, traveling wave tube RF generation, etc. The new power converter is based on a series resonant power converter (SRC) which is modified by adding low power auxiliary circuitry. The so obtained auxiliary SRC (ASRC) maintains zero-voltage switching (ZVS) for both main and auxiliary devices over the entire operating range. The ASRC can operate and regulate voltage even at no load conditions. The additional reactive energy used to maintain soft switching and voltage regulation at light loads is controllable independently of power converter load. This contributes to higher efficiency, especially at heavy loads. The ASRC control is identical to that of a standard SRC, so fast and robust transient response can be obtained with relatively simple controller structure. The paper also presents power converter analysis and design, and experimental results from a 100 kW, 150 kV prototype.

DC and Transient Performance of 4H-SiC Double-Implant MOSFETs

SiC vertical MOSFETs were fabricated and characterized, achieving blocking voltages around 1 kV and specific on-resistances as low as RSP,ON=8.3 mOmegamiddotcm2. DC and transient characteristics are shown. Room and elevated temperature (up to 200degC) 600 V/5 A inductive switching performance of the SiC MOSFETs are shown with turn-on and turn-off transients of approximately 20-40 ns.

Fuzzy logic control of resonant converters for power supplies

Fuzzy logic control (FLC) technology has drastically reduced the development time and deployment cost for the synthesis of nonlinear controllers for dynamic systems. As a result there have been an increased number of FLC applications. The authors illustrate their efforts in FLC technology transfer aimed at controlling a resonant converter power supply. The authors discuss the development of FLCs for a series-resonant converter (SRC) and a single-ended parallel multi-resonant converter (SEP-MRC). The authors emphasize the role of fuzzy logic in the development and deployment of these applications, and show how to meet their stringent throughput requirements by compiling the FLC into look-up tables.

3kV 4H-SiC Thyristors for Pulsed Power Applications

Due to the Silicon Carbide (SiC) material’s high electric field strength, wide bandgap, and good thermal conductivity, 4H-SiC thyristors are attractive candidates for pulsed power applications. With a thinner blocking layer almost an order of magnitude smaller than its Silicon (Si) counterpart, these devices promise very fast turn-on capabilities as full conductivity modulation occurs >10 times faster than comparable silicon thyristors, low leakage currents at high junction temperatures and at high voltage, and much lower forward voltage drop at high pulse currents. Our progress on the development of large area (4mm x 4mm) SiC thyristors is presented in this paper.