A method and a device for assigning the inductance or admittance to the rotor position of a synchronous machine having a stator and a rotor with or without permanent magnets. In operation, the synchronous machine is activated by way of timed terminal voltages and the inductance or admittance is calculated from the terminal voltages and the measured current response. In this case, the variation of the inductance or admittance over the rotor rotation under the boundary condition of an at least two-dimensional current vector that is unchanged in stator coordinates, is used as key information for the positional assignment.

An inverter control apparatus and a control method thereof are provided. The inverter control apparatus and a control method thereof stably operate a three-phase motor using a capacitor having a small capacitance for a DC link. The inverter control apparatus includes a current sensor to sense an output current of the inverter, a voltage sensor to sense a DC-link voltage of the inverter, and a controller to generate an average of a periodically varying rotor based q-axis current boundary value based on the output current and the DC-link voltage to generate a current reference on the basis of the average of the rotor based q-axis current boundary value, and to drive a three-phase motor based on the current reference. Stabilized variable speed control of a motor by using a small-capacitance capacitor for a DC link of an inverter is performed and reliability of an inverter circuit improved.

A method for sensorless control of a separately excited synchronous machine having a rotor includes the following steps: feeding a test signal on a parameter of an electrical current driving the rotor; measuring the parameter of the electrical current driving the rotor on an axis of the coordinate system describing the synchronous machine; determining an error signal by correlating the measured parameter of the electrical current driving the rotor with a temporally delayed test signal which is determined from the fed test signal; and adjusting a rotor angle as a reaction to the error signal if the error signal has a value not equal to zero.

An inverter control device according to an embodiment includes an inverter main circuit, a current instruction generator, a voltage instruction generator, an estimator, a high-frequency wave superimposer. The inverter main circuit is electrically connectable to a predetermined rotational drive target. The current instruction generator generates a current instruction. The voltage instruction generator generates a voltage instruction causing a current output from the inverter main circuit to be equal to the current instruction. The estimator calculates an estimation rotational phase angle of the rotational drive target. The high-frequency wave superimposer superimposes a high-frequency wave on the current instruction or the voltage instruction according to a relation between a feature amount of the rotational drive target and a threshold.

The disclosure relates to a method for determining phase currents of a rotating multiphase electrical machine fed by means of a PWM-controlled inverter. In this case, injection voltages applied in at least one stipulated PWM period are determined. An evaluation direction for a phase current vector is also determined and a division of current measurements for the individual phase currents is determined on the basis of the evaluation direction. The phase currents are then determined on the basis of the previously determined division of the current measurements.

Power based self-sensing of a rotor position of an SR motor at mid to high speeds and low torque is achieved by an SR motor control system by comparing the motor power to an injection maximum power. A position current pulse is injected to a stator pole in response to the motor power being less than the injection maximum power. An actual stator current created by the position current pulse is compared to an estimated stator current, and a stored estimated rotor position in a memory is updated to a new estimated rotor position if the actual stator current is not equal to the estimated stator current.

A rotary current machine system and method for controlling an electric rotary current machine, in particular an induction machine, having a rotor, a stator and at least two phase windings is disclosed. At least one electrical signal, in particular a voltage signal, is applied to at least one phase winding, preferably all phase windings, of the rotary current machine, and the current waveform in the at least one phase winding is measured. An intermodulation signal component, induced in the rotary current machine by slotting effects and magnetic saturation effects, which is determined from the current waveform measured in the at least one phase winding, is used for controlling the rotary current machine.

An apparatus and a method for detecting a motor rotor position are provided. The method for detecting a motor rotor position includes: transmitting test current commands and preset angles to a field oriented control circuit before a motor rotor rotates, to enable the field oriented control circuit to generate feedback currents, determining current peaks of the feedback currents, and comparing the current peaks of the feedback currents, and when determining that a current peak of a feedback current with a largest current peak in the feedback currents is greater than a current peak of another feedback current, outputting, according to a largest current peak current command corresponding to the feedback current with the largest current peak, a preset angle corresponding to the largest current peak current command as an initial angle position of the motor rotor.

Provided is a control device for a rotating machine including a magnetic pole position estimation unit, a vector calculation unit, a current command correction unit configured to correct a first d-axis current command and a first q-axis current command, to thereby output a second d-axis current command and a second q-axis current command, a voltage application unit configured to superimpose a high-frequency voltage including a specific frequency component on voltage commands on rotational coordinates. The magnetic pole position estimation unit is configured to estimate the position of the magnetic pole based on a state quantity of the specific frequency component. The current command correction unit is configured to correct the current commands so that a current amplitude of electrical angle frequency components is equal to or larger than a half of a current amplitude of the specific frequency component.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. If the supply of power to the motor is turned OFF to cause the motor to slow down and is turned back ON while the rotor speed exceeds a speed threshold, the controller electronically brakes the motor for a time interval to measure the phase current of the motor and detects the angular position of the rotor based on the measured phase current.