Patent ID: 7764031

Claim:
An AC-input type brushless DC motor comprising: a stator formed by winding a driving coil on a stator iron core via an insulator; a magnet rotor including a permanent magnet rotatably disposed to face the stator; a magnet position sensing circuit for sensing a magnet position of the magnet rotor; a rectifying circuit for rectifying an AC power supply in a full-wave manner; an inverter circuit provided top and bottom sides, the inverter circuit being formed of a plurality of switching elements bridge-connected together; a low DC voltage converting circuit, formed of a chopper circuit, for converting a high DC voltage obtained through the rectifying circuit into a substantially constant low DC voltage to be applied to the inverter circuit; a driving logic circuit for exciting the driving coils in a predetermined direction and sequence with the low DC voltage produced by the low DC voltage converting circuit in the full-wave manner via the inverter circuit based on a signal supplied from the magnet position sensing circuit; a current control circuit for controlling an average current to be supplied to the inverter circuit at a constant level; a current indication circuit for indicating a value of the average current supplied by the current control circuit at a constant level; a correlation indication circuit for indicating a correlation between the low DC voltage produced by the low DC voltage converting circuit and the value of the average current indicated by the current indication circuit in response to a value of a resistor to be connected; and a reference current indication circuit for determining a reference current value which is indicated by the current indication circuit in response to the value of the resistor to be connected, wherein the current indication circuit makes addition or subtraction, with respect to a reference current value determined by the current indication circuit, such that the average current falls into a correlation indicated by a correlation indication circuit.