Jacobus Daniel van Wyk

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Possibilities for minimizing component cost in variable- speed drives with frequency control by solid-state converter are investigated. It is shown that in a three-phase system voltage and frequency control of a three-phase squirrel-cage machine may be attained by PWM of the output of a simplified bridge inverter with only four switches. As the phase(More)
This paper presents a historical and philosophical perspective on a possible future for power electronics. Technologies have specific life cycles that are driven by internal innovation, subsequently reaching maturity. Power electronics appears to be a much more complex case, functioning as an enabling technology spanning an enormous range of power levels,(More)
Frequency-selective transmission line (TL) EMI filter can be used to attenuate the high frequency (HF) noise in power electronics systems. In order to understand the attenuation mechanism and to facilitate the design of the TL EMI filter, analysis of the differential mode (DM) TL EMI filter is given in this paper based on multi-conductor lossy transmission(More)
Miniaturization of hybrid integrated buck converters is impeded by the difference in growth laws in current rating for silicon and for inductors as current rating increases. In the 20 A range, this leads to the attractive feasibility of planarizing the output inductor as the largest component by utilizing low-temperature cofired ceramic technology in the(More)
Integrated transmission-line filters were previously proposed to attenuate conducted electro-magnetic interference (EMI) produced by high-frequency switching power converters. In this work, such a filter is manufactured using planar processing technologies, and it is tested for the first time with a 500W, front-end, single-phase power factor correction(More)
A low-profile power inductor fabricated using low temperature co-fired ceramics (LTCC) technology has been demonstrated to improve the light-load efficiency of a 5 V-to-1 V, 12.5 A buck converter operating with a switching frequency of 4 MHz, without the use of additional control circuitry. Variation in inductor geometry is performed experimentally to study(More)
A high power density integrated electronic ballast for low wattage high intensity discharge (HID) lamp is proposed in this paper. Packaging and integration technologies are explored to fully utilize the three-dimensional space, therefore improve the power density of the system. This paper focuses on the power passive integration, including the integrated(More)
The question of eliminating distorted current waveforms from power networks by active power filters is investigated. If the active current is subtracted from the distorted current, the compensating equipment must be capable of generating the inverse of this difference. Addition of this compensating current to the distorted current then eliminates the(More)
Power semi-conductors are able to achieve switching transients within a few nanoseconds and possibly even faster. These fast switching transients will need to be measured and analyzed thoroughly. In this paper four different types of shunt constructions and installations are tested on the same power electronics circuit, giving widely diverse results.(More)
Gallium nitride (GaN) power semiconductor technology offers a potential for significant performance increase in power electronic converters. This potential cannot be fully exploited if GaN devices are used as drop-in replacement for silicon devices in existing systems. This paper investigates the switching limits influenced by the device output parasitic(More)