Compensating Frequency Converter Nonlinearity

Voltage and/or current of multiphase systems are usually controlled using frequency converters (FCs). Typically, these FCs consist of several half bridges and, due to their working principle, their output voltage will depend on the output current nonlinearly. Many well known compensation methods (CMs) rely on the assumption that the current is nearly constant during one switching cycle. However, with decreasing load inductances this assumption may not be fulfilled and therefore these methods may not succeed in achieving full compensation. This contribution provides a CM, which takes the so-called ripple current into account and is therefore especially useful when dealing with small load inductances.