Patent ID: 8183813
Filing Date: 2012-05-22
Classification: H02M,H02P

Abstract:
1. A frequency converter for supplying power between a polyphase alternating electricity source and an electric machine, the frequency converter comprising: a network rectifier connected to the alternating electricity source; and an inverter connected to the electric machine; in which power supply of the network rectifier and the inverter is implemented with solid-state changeover switches; in which changeover switches comprises an antiparallel-connected diode fitted in parallel with a controllable switch; wherein the network rectifier and the inverter are connected to each other with an intermediate circuit, which intermediate circuit is implemented without a passive storage; each positive changeover contact of the network rectifier is controlled to be continuously conductive in each respective phase of the network rectifier in which the transient value of the phase voltage is greatest, for supplying power between the alternating electricity source and the intermediate circuit; each negative changeover contact of the network rectifier is controlled to be continuously conductive in each respective phase of the network rectifier in which transient value of a phase voltage is smallest, for supplying power between the alternating electricity source and the intermediate circuit; the frequency converter comprises a determination for detecting an operational deviation; and a control of the changeover switches of the inverter is fitted to be disconnected on the basis of the detected operational deviation, wherein the inverter of the frequency converter is fitted to regulate a supply voltage of the electric machine with an inverter control for providing variable-frequency and variable-amplitude voltage or current therein; and in that each changeover switch of the inverter is controlled to be continuously conductive in each respective phase of the inverter in which a transient value of the supply voltage is greatest in absolute value, such that one changeover switch at a time is controlled to be continuously conductive, and wherein the current of the intermediate circuit is determined from the switching state of the changeover switches of the inverter; and in that at least one changeover switch of the network rectifier is controlled on the basis of the current of the intermediate circuit determined from the switching state of the changeover switches of the aforementioned inverter.