| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a current detection circuit that can exactly detect a current of each phase during one cycle. <P>SOLUTION: A current detection part 8 that is provided in an inverter unit of three phases having a switching element at each phase comprises: an amplifying part 9 that amplifies a signal from a current sensor that detects a composite current of each phase; sample hold circuits 11 to 13 that hold signals from the current sensor amplified at the amplifying part 9; an error voltage source 14; changeover switches 15 to 17 that switch the signals held at the sample hold circuits; a decoder 10a that specifies which phase current flows to the current sensor from the phase state of the inverter unit, and makes the sample hold circuit perform sampling and hold a voltage corresponding to the phase current; and a timer 10b that measures an invariable time of the phase state. Only when the invariable time of the phase state exceeds a prescribed time, a voltage from the current sensor is held at the sample hold circuit, and otherwise an error voltage is held. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
