| 摘要 |
A stationary position detection circuit and a motor drive circuit are provided to improve detection accuracy by amplifying an electrical signal through the increase of the number of alternations by using alternating current. In a stationary position detection circuit(4), a current quantity detector makes an alternating current, flowing in a first direction and a second direction, flowing into a load through a control circuit controlling an inverter circuit(2), detects that the alternating current flowing in the first direction reaches an alpha value and then makes the alternating current flowing in the second direction by gradually decreasing the alternating current through the control circuit, detects that the alternating current flowing in the second direction reaches a beta value and then makes the alternating current flowing in the first direction again by gradually decreasing the alternating current through the control circuit, and repeats the above-described steps such as the detecting and controlling operation with a predetermined frequency. A time measuring unit measures a first time that the alternating current varies from the alpha value to the beta value and a second time that the alternating current varies from the beta value to the alpha value. A time difference amplifier converts the first and second times into electric signals and amplifies the same with the first and second times corresponding to the repeated frequency of the above-step. A position detector detects a position of a rotor(10) when stopping according to a value of the electric signals. |
