Abstract: A signal converter for generating switch drive signals for a multi-level converter includes a logic. In the presence of the first polarity, the logic sets the first switch drive signal and the third switch drive signal according to the pulse width modulation input signals, and sets the second switch drive signal to a signal level indicating a closed state of the second switch and the fourth switch drive signal to a given signal level indicating an opened state of the fourth switch. In the presence of the second polarity, the logic sets the second switch drive signal and the fourth switch drive signal according to the pulse-width-modulation input signals, sets the first switch drive signal to a signal level indicating an opened state of the first switch, and sets the third switch drive signal to a signal level indicating a closed state of the third switch.

Abstract: A signal converter for generating switch drive signals for a multi-level converter comprises an input for a first pulse-width-modulation signal and a second pulse-width-modulation signal and an input for a polarity signal indicating a first polarity or a second polarity. The signal converter comprises four outputs for four switch drive signals for driving four switches of the multi-level converter. Also, the signal converter comprises a logic circuit for driving the switch drive signals in dependence on the polarity signal. The logic is configured to drive the switch drive signals in dependence on the polarity signal.

Abstract: A capacitor power supply unit for generating an auxiliary direct voltage supply from a main alternating voltage supply for powering an electrical consumer includes a storage capacitor and a charging capacitor. The storage capacitor provides an auxiliary direct voltage supply for powering an electrical consumer and the charging capacitor is operable for charging the storage capacitor with current generated by a main alternating voltage supply. Rectifying means rectify the current charging the storage capacitor. Switching means switch between first and second switch positions for enabling the charging capacitor to charge the storage capacitor and for disabling the charging capacitor from charging the storage capacitor. A switching time-determining member provides a switching time control signal to the switching means as a function of voltage output by the charging capacitor.