CONTROL DEVICE AND METHOD FOR OPERATING AN ELECTRICAL MACHINE DRIVEN BY AN INVERTER

摘要

The invention relates to a method for operating an electrical machine (1) controlled by an inverter (2), wherein the inverter (2) comprises half-bridge branches (10-U, 10-V, 10-W) having power components in the form of controllable power switching elements (3) and power diodes (4) respectively connected in parallel therewith, wherein each of the half-bridge branches (10-U; 10-V; 10-W) is arranged on a separate semiconductor module (11-U; 11-V; 11-W), which are arranged jointly on a baseplate (12), wherein the phase currents (1_U, 1_V, 1_W) flowing through the half-bridge branches (10-U, 10-V, 10-W), the voltages present at the power components and temperatures (t_Sens_U, t_Sens_V, t_Sens_W) on the semiconductor modules (11-U, 11-V, 11-W) are determined, from the current (1_U; 1_V; 1_W) respectively flowing at a power component and from the voltage respectively present a power loss (P) is calculated for each of the power components, from the power losses (P) a relevant temperature swing (&Dgr;t; &Dgr;t_Sens) is determined for each of the power components and for temperature sensors (13-U, 13-V, 13-W) serving to determine the temperatures on the semiconductor modules, a temperature (TempCooler) of the baseplate (12) is determined from the determined temperatures (t_Sens_U, t_Sens_V, t_Sens_W) on the semiconductor modules (11-u, 11-V, 11-W) and the determined temperature swings (&Dgr;t_Sens) at the temperature sensors (13-U, 13-V, 13-W), and a torque or a power of the electrical machine (1) is determined in a manner dependent on the determined temperature swings (&Dgr;t) and the determined temperature (TempCooler) of the baseplate (12).