Optimal control and appropriate pulse width modulation for a three-phase voltage DC-link PWM converter

Abstract

L e h r s t u h l f u r E r z e u g u n g u n d A n w e n d u n g e l e k t r isct-ier E r i e r y i e R u h r--U n i v e r s i ty B oc h u m , D -4 6 3 0 B o c k i CA r -r i , c3e r-rna n y Abstract -Control strategies for three-phase voltage dc-link PWM converters presented so far always use a portion of the available switching operations of the converter valves for control of the dc-link voltage. The new control strategies presented here use all allowed switching operations of the converter such that the converter has a line-friendly performance from point of view of the utilities or the consumer. In case of an ideal converter (switching frequency of the semiconductor devices is infinitely high, no losses) and a distortion-free supply network, the power factor becomes equal to unity under steady-state conditions and the dynamic characteristics of the control system are sufficient. In order to reach this "line-friendly" performance with an existing converter and to keep the expenditure for the line-side filter low. appropriate PWM at a high switching frequency ( > 10 kHz) is necessary. The theory of the control strategies and appropriate PWM are presented. Practical results obtained with an IGBT-converter illustrate the dynamic and steady-state performance of the new control system in both energy-flow directions. The new control strategies are most economically used in the medium power range ( 5 kW to 200 kW).

Operation of One-Cycle Controlled Three-Phase Active Power Filter With Unbalanced Source and Load

“…5, the voltages at nodes A, B, C referring to neutral point "O" can also be expressed by (11) In addition, since three-phase unbalanced line voltages as depicted in Fig. 4 include zero-sequence component, then (12) can be achieved (12) where is the zero-sequence component. Moreover, combining (11) and (12) yields (13) Substituting (13) and (11) into (10) results in (14) Simplifying above equations yields (15) Furthermore, in the time domain, (15) can be simplified into (16) where , , and are the zero-sum components.…”