Abstract: The present invention addresses the problem of providing a method which makes it possible to simply evaluate an output of an initial position detection signal for a permanent magnetic field, along with providing a method for correcting errors that occur in the initial position detection signal. As a means for solving said problem, an MPU (51) obtains a correction value in which an offset error has been corrected by multiplying a first measurement value or a second measurement value, which are measured for each conduction pattern when an offset error occurs during position detection of a permanent magnetic field, by a correction coefficient A and estimates the position of the permanent magnetic field on the basis of the correction value.

Abstract: The present invention addresses the problem of providing a method for detecting a magnetic field location in an electric motor, said method making it possible to lower costs using simple hardware and software, and instantaneously detect permanent-magnet field location. As a means for solving said problem, an MPU (51) sequentially selects one from six conduction patterns using a phase at which one-phase conduction occurs without branching at a neutral point among three-phase coils as a phase to be measured, applies a sensing current to the three-phase coils, and uses a timer (56) to measure a pulse-width time until the coil current detected by a current sensor (53) reaches a current threshold, and stores the same as measurement data.

Abstract: The present invention addresses the problem of providing a method for detecting magnetic field location which can realize low cost by using simple hardware and software and can detect a rotor location in units of excitation sections in 120°-energization without generating sensing noise at the time of initiation. As a solution, an MPU (51) obtains, through calculation, a neutral point potential from an energization-phase voltage measured by an A/D conversion circuit (53), obtains the difference between the neutral point potential and a non-energization-phase voltage, performs magnitude comparison between the difference and a negative-side threshold value in the case where the present location is an odd-numbered section or between the difference and a positive-side threshold value in the case where the present location is an even-numbered section, and determines the end point of the 60°-energization section when the difference exceeds a threshold value in a direction away from the neutral point potential.

Abstract: The present invention addresses the problem of proposing a method for driving a sensorless motor, wherein the method is different from a conventional rotor position estimation method according to a time axis and performs rotor position estimation according to an angle axis, thus making it possible for excitation switching to always be achieved at an optimal angle in response to a change in speed. According to the present invention, an MCU (5) starts excitation of a coil at an excitation section starting point, measures an induced voltage component generated in the coil by a certain period of energization, integrates the voltage component, and sets an excitation section ending position when the integral value reaches zero. In addition, the motor is continuously rotated by repeating the same integration operation by switching to an excitation pattern in the next excitation section.