초록 ▼

A control device calculates a voltage command value of a voltage step-up converter based on a torque command value and a motor revolution number and calculates the on-duty of an NPN transistor based on the calculated voltage command value and a DC voltage from a voltage sensor. Under the conditions

A control device calculates a voltage command value of a voltage step-up converter based on a torque command value and a motor revolution number and calculates the on-duty of an NPN transistor based on the calculated voltage command value and a DC voltage from a voltage sensor. Under the conditions that the on-duty is influenced by a dead time and the DC voltage is smaller than a predetermined set value, the control device controls NPN transistors to step-up or step-down the voltage while fixing the on-duty at 1.0.

대표청구항 ▼

What is claimed is: 1. 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

What is claimed is: 1. 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. 2. The voltage conversion device according to claim 1, wherein said internal resistance is set to a maximum value of the internal resistance that can be taken by said power supply. 3. The voltage conversion device according to claim 1, wherein said internal resistance is set to a measured value of said internal resistance. 4. The voltage conversion device according to claim 1, wherein said internal resistance is set based on the temperature of said power supply. 5. The voltage conversion device according to claim 1, wherein said maximum value of the DC current is set based on a detected value of an output voltage of said voltage converter and a detected value of said power supply voltage. 6. A voltage conversion device variably changing an input voltage to an inverter, the voltage conversion device comprising: a voltage converter including an upper arm that is made ON at a first on-duty and a lower arm that is made ON at a second on-duty determined by subtracting said first on-duty from 1, 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 switching of said upper arm and said lower arm by setting said first on-duty to an appropriate on-duty, when said first on-duty calculated based on a voltage command value of the voltage conversion by said voltage converter is influenced by a dead time of said upper arm and said lower arm and a power supply voltage is influenced by said dead time, wherein when said first on-duty calculated based on said voltage command value is larger than a maximum effective on-duty and smaller than a longest on-duty for keeping said upper arm ON for a control period length and said power supply voltage is at least a predetermined set value, said control device controls switching of said upper arm and said lower arm by setting said first on-duty to said maximum effective on-duty, said maximum effective on-duty is determined by dividing, by said control period length, an effective control period length determined by subtracting said dead time from said control period length, and said predetermined set value is determined by subtracting, from an allowable maximum voltage of said power supply, a product of an internal resistance of said power supply and a maximum value of DC current of said power supply when said first on-duty is switched to said longest on-duty. 7. The voltage conversion device according to claim 6, wherein when said first on-duty calculated based on said voltage command value is larger than the maximum effective on-duty and smaller than the longest on-duty for keeping said upper arm ON for the control period length and said power supply voltage is smaller than the predetermined set value, said control device controls switching of said upper arm and said lower arm by setting said first on-duty to said longest on-duty. 8. A voltage conversion device variably changing an input voltage to an inverter, the voltage conversion device comprising: a voltage converter including an upper arm that is made ON at a first on-duty and a lower arm that is made ON at a second on-duty determined by subtracting said first on-duty from 1, and performing voltage conversion between a power supply and said inverter by switching of said upper arm and said lower arm, said first on-duty being a period for which the upper arm is kept ON in one control period length and said second on-duty being a period for which the lower arm is kept ON in one control period length; and a control device controlling switching of said upper arm and said lower arm by setting said first on-duty by making a switch, at a predetermined ratio, between a maximum effective on-duty and a longest on-duty at which said upper arm is kept ON for a control period length, when said first on-duty calculated based on a voltage command value of the voltage conversion by said voltage converter is influenced by a dead time of said upper arm and said lower arm, wherein said maximum effective on-duty is determined by dividing an effective control period length by said control period length, where said effective control period length is determined by subtracting said dead time from said control period lengths, 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. 9. 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 in a case where a voltage command value of the voltage conversion by said voltage converter is larger than a power supply voltage and smaller than a predetermined voltage, said control device controls said voltage converter by setting said duty using a first duty that is a duty when a voltage of at least said predetermined voltage is said voltage command value and a second duty that is a duty when said power supply voltage is said voltage command value, and said control device sets said duty by making a switch between said first duty and said second duty at a predetermined ratio. 10. 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 in a case where there is a possibility that a surge of DC current of said power supply occurs, said control device controls said voltage converter by setting said duty using a first duty that is a duty when a voltage of at least a predetermined voltage is a voltage command value and a second duty that is a duty when a power supply voltage is said voltage command value, and said control device sets said duty by making a switch between said first duty and said second duty at a predetermined ratio. 11. A voltage conversion device variably changing an input voltage to an inverter, the voltage conversion device comprising: a voltage converter including an upper arm that is made ON at a first on-duty and a lower arm that is made ON at a second on-duty determined by subtracting said first on-duty from 1, 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 switching of said upper arm and said lower arm by changing a carrier frequency at which switching of said upper arm and said lower arm is controlled, according to an increase of said first on-duty, when said first on-duty calculated based on a voltage command value of the voltage conversion by said voltage converter is influenced by a dead time of said upper arm and said lower arm, wherein said control device changes said carrier frequency in a predetermined period at start of said voltage conversion and in a predetermined period at a transition to a state where said voltage conversion is stopped. 12. 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 wherein when a voltage command value of the voltage conversion by said voltage converter is larger than a power supply voltage and smaller than a predetermined voltage, said control device controls said voltage converter by changing a carrier frequency at which switching of said upper arm and said lower arm is controlled, wherein when said control device performs control for stepping down an output voltage of said voltage converter or control for stepping up the output voltage of said voltage converter and said voltage command value is larger than said power supply voltage and smaller than said predetermined voltage, said control device changes said carrier frequency. 13. 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 wherein when a voltage command value of the voltage conversion by said voltage converter is larger than a power supply voltage and smaller than a predetermined voltage, said control device controls said voltage converter by changing a carrier frequency at which switching of said upper arm and said lower arm is controlled, wherein when said control device performs control for stepping down an output voltage of said voltage converter and said voltage command value is larger than said power supply voltage and smaller than said predetermined voltage, said control device changes said carrier frequency. 14. 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 wherein when a voltage command value of the voltage conversion by said voltage converter is larger than a power supply voltage and smaller than a predetermined voltage, said control device controls said voltage converter by changing a carrier frequency at which switching of said upper arm and said lower arm is controlled, wherein said predetermined voltage is determined based on the dead time of said voltage converter.