Patent ID: 7656690

Claim:
A voltage conversion device variably changing an input voltage to an inverter, the voltage conversion device comprising: a voltage converter including an upper arm and a lower arm and performing voltage conversion between a power supply and said inverter by switching of said upper arm and said lower arm; and a control device controlling said voltage converter so as to reduce influence of a dead time of said voltage converter on a duty of said switching, said duty being a period for which the upper arm or the lower arm is kept ON in one control period length, wherein when a voltage command value of said voltage conversion, corresponding to a calculated target value of an input voltage for the inverter, is larger than a power supply voltage and smaller than a predetermined voltage and said power supply voltage is smaller than a predetermined set value, said control device controls said voltage converter by setting said duty to a duty for instructing to stop said voltage conversion, when said voltage command value is larger than said power supply voltage and smaller than said predetermined voltage and said power supply voltage is at least said predetermined set value, said control device controls said voltage converter by setting said duty to a duty for instructing to perform said voltage conversion, and said predetermined set value is set based on an allowable maximum voltage of said power supply, a maximum value of DC current of said power supply when said voltage converter makes a transition to a state where said voltage conversion is stopped, and an internal resistance of said power supply.