Advanced current controllers of bi-directional converters with nearly sinusoidal input current and with minimized switching frequency

A newly developed technique, the predictive adaptive switching pattern (PASP), applied for tolerance band (TB) current control of an induction machine supplied by a voltage source inverter (VSI) is presented. This technique is based on the so called regular switching pattern (RSP) and its improved version the adaptive switching pattern (ASP). ASP was designed to avoid some of the shortcomings of RSP. It employs two TBs to suppress fast switchings (FS) and double commutations (DC) in switching state changes. To improve further the performance of ASP, a more advanced and more sophisticated technique, the PASP was developed. It works once again with only one TB similarly to RSP, suppresses FS and DC as well as reduces the number of device switch-overs and those of switching states over ASP. The price that has to be paid for the improvement is the requirement for more computing power. Digital signal processors (DSP) and IGBTs or MOSFETs are the suitable hardware for the implementation of PASP. All three algorithms are based on the adjacency principle (AP) up to a different degree. According to AP the output voltage vector of VSI is selected from the subset neighbouring the reference output voltage vector ν¯*. After briefly describing the drive system an overview of RSP and ASP is given. The main part of the paper is the presentation of the novel PASP algorithm. Simulation results compare the performance of the three algorithms. The conclusions are drawn based on the numerical results