Methods and apparatus for reducing the common mode voltage generated by eliminating zero-voltage vectors in a rectifier/inverter variable frequency drive (VFD) system includes comparing three phase voltages to each other to determine a maximum voltage in one phase, a minimum voltage in another phase...http://www.google.se/patents/US7164254?utm_source=gb-gplus-sharePatent US7164254 - Modulation methods and apparatus for reducing common mode voltages
