| 摘要 |
PURPOSE:To prevent malfunctions of a motor and heating and breakdown of switching elements due to malfunctions of IC that may occur at the time of power application or supply voltage drop. CONSTITUTION:Voltage rectified through a power circuit 1 is switched to three- phase full wave through a group 2 of switching elements. A position detector 3 detects the position of the rotor of a motor, and generates signals; a switching circuit 4 determines the actuation of the switching element group 2 according to the signals from the position detector 3. A group 5 of protective diodes 5 individually connects the control terminal of each of the lower arms of the switching element group 2 to the anode side, and thereby integrates the cathode side. The protective diode group 5 is connected with a low voltage detecting circuit 6 that opens the lower arms of the switching element group 2 by means of supply voltage. |
