Patent ID: 9673744
Date: 2017-06-06
CPC Classifications: B60L,H02H,H02M,H02P,Y02T

Claim:
1. An operating state circuit for driving an inverter, which supplies an n-phase supply voltage to an n-phase electric machine via a plurality of phase connections, where n≧2, the circuit comprising: an evaluation device connected to the inverter, wherein each of the plurality of phase connections are connected to the output voltages of the inverter and the evaluation device is configured to detect output voltages of the inverter at each of the plurality of phase connections and to determine a speed of the electric machine on the basis of the detected output voltages; a low-voltage energy supply device connected to the evaluation device, the low-voltage energy supply device configured to supply electrical energy to the evaluation device; a drive device coupled to the evaluation device and drives switching devices of the inverter to switch into at least one of the group including a freewheeling state and an active short circuit, in dependence on the determined speed, wherein the drive device drives switching devices of the inverter into the freewheeling state when the determined speed is less than a predetermined speed threshold value and drives switching devices of the inverter into the active short circuit when the determined speed is greater than or equal to the predetermined speed threshold value; and an energy supply device, which is directly coupled to a DC voltage intermediate circuit, the evaluation device, and the drive device and which is designed to supply electrical energy from the DC voltage intermediate circuit to the evaluation device and the drive device only when the low-voltage energy supply device has failed or another fault state has occurred on the low-voltage side of the inverter.