Patent ID: 9154051
Filing Date: 2015-10-06
Classification: B60L,H02M,H02P,Y02T

Abstract:
1. An operating state circuit for controlling an inverter including half bridges, each having switching devices, which supplies an n-phase electric machine with an n-phase supply voltage via phase connections associated with the respective half bridges, where n≧1, including: an evaluation device which is connected to the phase connections of the inverter, and to input terminals of the inverter on the other hand, and which is designed to detect an input voltage of the inverter and phase currents at the phase connections of the inverter; and a control device which is coupled to the evaluation device and which is designed to switch the inverter from a short-circuit state to a freewheeling mode as a function of the detected input voltage, wherein the evaluation device is designed to generate a freewheeling trigger signal and to output it to the control device if the detected input voltage is less than an adjustable freewheeling threshold value, and wherein the control device is designed to transfer the respective switching devices of the half bridges to an open state after receiving the freewheeling trigger signal only if the respective detected phase current at the associated phase connection has a zero crossing or a current direction pointing out of the inverter.