| 摘要 |
PROBLEM TO BE SOLVED: To accurately determine the direction of coil current during a dead time period during which individual switches are simultaneously turned off and make the increase/decrease ratio of coil current correspond to a command value in a power conversion device that carries out power conversion by alternately turning on and off the high-side switches and the low-side switches connected to a coil. SOLUTION: The voltage at the junction point between switches SW1, SW2 is divided at a detection circuit 22 and a detection signal indicating the direction of current passed through the coil L (the increasing/decreasing direction) is thereby generated. The direction of coil current (the increasing/decreasing direction) during a dead time period is determined based on this detection signal and a PWM signal outputted from a PWM signal generation unit 20. The operation mode of a power conversion circuit 10 is identified from the result of this determination to set a ratio correction value of the PWM signal and an offset value Tos for the control period of the PWM signal. As a result, it is possible to quickly detect change in the operation mode of the power conversion circuit 10 and make the increase/decrease ratio of coil current correspond to a ratio command value (switching ratio). COPYRIGHT: (C)2009,JPO&INPIT
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