| 摘要 |
<p>A surge voltage generated by a switching operation of an IGBT element and a voltage fluctuation generated by an equivalent DC resistor of capacitor (C2) are superimposed on an input voltage Vm of an inverter (14). The equivalent DC resistor has such a temperature dependency that the resistance value is increased as the capacitor temperature Tc is lowered. Moreover, the IGBT element has such a temperature dependency that the voltage resistance of the element is lowered as the inverter temperature Tiv is lowered.When the capacitor temperature Tc is lower than a predetermined threshold value, a control device (30) reducers the upper limit of the input voltage Vm by an amount corresponding to the voltage fluctuation from the upper limit value at a high temperature. Thus, the control device (30) controls a target voltage of a boosting converter (12) so that the output voltage will not exceed its upper limit value. As a result, it is possible to assure the allowance range of the surge voltage.</p> |
