Abstract: A method and an apparatus for position-sensorless motor control are provided, wherein an undesired sound is reduced and the S/N ratio in a detection of a current response to a rotor-position estimation signal increases without control delay, in contrast to the prior art, especially when a rotor is at a stop or slowly revolves. In the position-sensorless motor control method according to the invention, a rotor-position estimation current signal is superimposed on the &ggr;-axis direction component of a target current vector, which represents target currents of stator windings. The period of the rotor-position estimation current signal is an even multiple of a PWM carrier period, and varies at random. Furthermore, the amplitude thereof increases along with increasing of the amplitudes of the target currents.

Abstract: The invention provides an motor drive apparatus comprising a detector for detecting a terminal voltage in a non-energized phase and a detector for detecting a DC voltage applied to the main line of an inverter. The rotation of the brushless motor is controlled by specifying the inverter circulating current period from the terminal voltage and the DC voltage and calculating the magnetic pole position of the rotor from the terminal voltage after the end of the inverter circulating current period and a waveform of the terminal voltage predetermined from the characteristics of the brushless motor. As a result, the brushless motor can be rotated stably throughout a wide revolution range from low to high speeds.

Abstract: A torque current component and an exciting current component of primary AC currents which are supplied to a stator of a three-phase induction motor are commanded independently of each other in accordance with a command rotational angular velocity and a rotational angular velocity of the three-phase induction motor rotating an agitator, and the rotational angular velocity of the three-phase induction motor is controlled by changing the magnitude and frequency of each of the primary AC currents. Furthermore, a test operation is carried out by giving the command angular velocity so as to make constant the angular velocity of the motor, and the laundry amount is estimated corresponding to an output torque of the motor in the test operation.

Abstract: A motor control apparatus and a motor unit having such a motor control apparatus according to the present invention are constructed to detect a terminal voltage for switching elements of the same phase in a dead time period by a voltage output circuit 10, and to detect the instant when the sign of a phase current changes from the detected terminal voltage by a current sign change detection part 11. Based on the phase of a current sign change timing provided from the current sign change detection part 11 and the phase of a phase applied voltage, the first applied voltage control circuit 14 generates a phase applied voltage command to a switching element modulation circuit 9. Such arrangement makes it possible to provide motor continuous energization or motor energization drive near to 180 degrees at high efficiency, without the provision of any current sensors.

Abstract: A method for readily measuring each motor parameter with high precision, with an induction motor at rest, and an apparatus for controlling the induction motor using these motor parameters are provided. The induction motor is set to a single-phase feed state or a feed state equivalent to that state. First, a stator resistance is measured from a current value and a voltage value at the time when a direct current command is given. Then, the current command of a current having an appropriately high frequency and a known current differential value is given to find a rotor resistance and a leakage inductance from current values and voltage values at two different times and the previously obtained stator resistance value. Then, the current command of a sine wave current having an appropriately low frequency is given to find a mutual inductance using the current value and the voltage value at the time. These measured values are used for a slip frequency operation and a speed estimation operation.