K. De Gusseme

Small-signal Laplace-domain analysis of uniformly-sampled pulse-width modulators

As the performance of digital signal processors has increased rapidly during the last decade, there is a growing interest to replace the analog controllers in low power switching converters by more complicated and flexible digital control algorithms. Compared to high power converters, the control loop bandwidths for converters in the lower power range are generally much higher. Because of this, the dynamic properties of the uniformly-sampled pulse-width modulators used in low power applications become an important restriction for the maximum achievable bandwidth of control loops. After the discussion of the most commonly used uniformly-sampled pulse-width modulators, small-signal frequency- and Laplace-domain models for the different types of uniformly-sampled pulse-width modulators are derived theoretically. The results obtained are verified by means of experimental data retrieved from a test setup.

Distributed Generation for Mitigating Voltage Dips in Low-Voltage Distribution Grids

The presence of synchronous and induction generators has a positive effect on the retained voltage (the lowest rms voltage during the event) during voltage dips in high voltage networks. The impact of converter-connected distributed-generation (DG) units has been reported to be negligible, as most converters operate at unity power factor, and the currents injected in the grid are limited to the nominal current of the converter. However, the impact of DG units on the distorted grid voltage is strongly dependent on the voltage level, and thus the grid impedance, of the concerned grid. This paper investigates and compares the effects of converter-based DG units, synchronous and asynchronous generators on the retained voltage during voltage dips in low voltage distribution grids.

Small-signal z-domain analysis of digitally controlled converters

As the performance of microcontrollers has increased rapidly during the last decade, there is a growing interest to replace the analog controllers in low power switching converters by more complicated and flexible digital control algorithms. Compared to high power converters, the control loop bandwidths for converters in the lower power range are generally much higher. Because of this, the dynamic properties of the uniformly-sampled pulse-width modulators (PWMs) used in low power applications become an important restriction to the maximum achievable bandwidth of the control loop. Though frequency- and Laplace-domain models for uniformly-sampled PWMs are very valuable as they improve the general perception of the dynamic behavior of these modulators, the direct discrete design of the digital compensator requires a

Design issues for digital control of boost power factor correction converters

z

Input current distortion of CCM boost PFC converters operated in DCM

-domain model for the combination modulator and converter. For this purpose a new exact small-signal

Sample correction for digitally controlled boost PFC converters operating in both CCM and DCM

z

A single switch boost converter with a high conversion ratio

-domain model is derived. In accordance with the zero-order-hold equivalent commonly used for “regular” digital control systems, this

A sampling algorithm for digitally controlled boost PFC converters

z

Digital control of boost PFC converters operating in both continuous and discontinuous conduction mode

-domain model gives rise to the development of a uniformly-sampled PWM equivalent of the converter. This

Reduction of the voltage distortion with a converter employed as shunt harmonic impedance

z