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A three-phase Y-rectifier is formed by the star connection of single-phase unity-power-factor rectifier systems and represents a highly interesting concept for the realization of the input stage of high-power telecommunications power supply modules using established single-phase technology. However, for stable operation, control and balancing of the independent dc output voltages of the phase rectifier systems is required. A novel, easy- to-implement dc output voltage control concept is proposed in this paper. Here, the mean value of all three dc output voltages is controlled, and, in addition, always two out of the three dc voltages are compared and balanced. The basic operating principle of the control is described, the theoretical limit for the admissible asymmetric loading of the dc voltages is calculated, and numeric results for a 10-kW system are given. Finally, the theoretical considerations are verified by measurements on a 3 x 1 kW V-rectifier prototype. [ABSTRACT FROM AUTHOR]

An ultra high power density 10-kW/500-kHz three- phase pulse-width modulation rectifier (Vienna Rectifier) is under development at the Power Electronic Systems Laboratory, ETH Zurich. From preliminary measurements and numerical simulations the total efficiency is assumed to be 95 % at full load, resulting in power losses of up to 150 W in each multichip power module that realizes a bridge leg of the rectifier. In order to maintain the required power density of the system high direct water cooling is employed where water is in direct contact with the module base plate. Based on the measured characteristic of the water pump (pressure drop dependent on the water flow rate) the geometry of different water channel structures below the module base plate is systematically optimized based on equations which are formulated using well-established fluid dynamics theory. The design optimization is constrained by the desire to keep the geometry of the water channels in a range which allows simple and low-cost manufacturing. The aim is to find a channel structure resulting in a minimum thermal resistance of the power module for a given pump characteristic. In this paper, a very simple slot channel is investigated. The dependency of the thermal resistance on the cooling system is calculated for various heights of the slot channel, and an optimized channel height is determined using the condition of simple manufacturability. The shortcomings of the simple slot structure are discussed, and a novel metallic inlay structure is introduced and optimized that results in a reduction of the thermal resistance of the direct water cooling scheme as compared to the slot channel system. All theoretical considerations are experimentally verified. The general optimization scheme introduced in this paper can easily be adapted to other cooling problems. [ABSTRACT FROM AUTHOR]

Focuses on the structure of the power circuit of a single-stage three-phase pulsewidth modulated (PWM) rectifier system (VIENNA Rectifier II). Characteristics of VIENNA Rectifier II in terms of time behavior and output voltage; Comparison with the conventional two-stage realization; Function of PWM rectifier; System control for symmetric magnetization of the transformer.