Invention is related to a method for controlling an alternating current electric machine with a frequency converter including a controllable machine bridge and a controllable line bridge, and a corresponding frequency converter. The method comprises calculating a line bridge control signal, controlling line current through the line bridge using the line bridge control signal, measuring or estimating rotor pole position of the electric machine, calculating a machine bridge control signal as a function of the rotor pole position, updating the machine bridge control signal when the rotor pole position changes, and controlling current of the electric machine through the machine bridge using the machine bridge control signal.

A motor controller (100) is provided for smooth operation of an electric motor (102), which mitigates torque ripple, noise and vibration effects, and increases a life span of the motor (102). The motor controller (100) includes a speed controller (120), current transformation units (128 and 130), a current controller (132), and a pulse width modulation (PWM) signal generator (134). The current controller (132) determines a duty cycle of PWM gate signals used for controlling a rotor (104) speed within a particular sector (302A) of the motor (102) based on a reference quadrature-axis current and an actual quadrature-axis current. The PWM signal generator generates the PWM gate signals having the determined duty cycle, controls the rotor (104) speed, and incrementally varies a current speed of the motor (102) to achieve a target speed by modulating operations of a specific pair of inverter switches (502C and 502E) using the PWM gate signals.

A motor controller includes a plurality of inverters that supply power to a corresponding motor of a plurality of motors through pulse width modulation control, a direct current power supply that supplies power to the plurality of inverters, and a capacitor connected parallel to the direct current power supply. Each of the plurality of inverters is categorized into one of a plurality of groups based on a switching frequency. All inverters in each of the groups have corresponding carrier signals being triangular wave signals determined based on a reference frequency assigned to the group. At least one of the triangular wave signals has at least one of a frequency or a phase different from a frequency or a phase of another triangular wave signal of the triangular wave signals.

A method for operating a position-sensorless BLDC motor of an oil pump (19) is proposed. When the oil pump (19) is put into operation and run up to speed, to warm an oil that is transported by the oil pump (19), the BLDC motor is operated in a pre-controlled-excited mode until the oil has a kinematic viscosity that allows the BLDC motor to be operated in a controlled mode above a motor-specific limiting speed of a rotor of the BLDC motor. Waste heat of the BLDC motor generated by the pre-control is in this case dissipated to the oil in the surrounding area of the oil pump (19).

This pre-control is intermittently interrupted in order to detect a voltage induced by the rotor in the unexcited coils of a stator of the BLDC motor, by means of which a rotor position and a rotor (rotational) speed are determined sufficiently accurately above the limiting speed of the rotor.

Above this limiting speed, once it is detected that it has been exceeded, a changeover is made to a controlled-excited mode of the BLDC motor.

Also proposed are a computer program, a computer program product, a heat-transfer medium system and a vehicle.

A power system for a brushless motor may include: a first circuit driving normal operation of the motor; a second circuit driving emergency operation of the motor; and a control circuit that manages: communications between the first and second circuits; and connection of the first and second circuits to the motor via connection switches. The first and second circuits each may be configured to power each phase of the motor via a star or delta connection. The control circuit may be configured to detect an operating anomaly through a message of incorrect operation to the control circuit, which in turn activates the connection switches to disconnect the first circuit from the motor and to connect the second circuit to the motor.

The torque of a permanent magnet motor is increased. There is provided a permanent magnet type motor with concentrated windings, in which each stator pole has a circumferential pitch of 185 or more in an electric angle. In this motor, the circumferential distribution of the magnetic flux density in an air gap surface of the rotor poles PR of the permanent magnet type has an approximately trapezoidal shape. Moreover, the induced voltages of the concentrated windings of the stator have an approximately trapezoidal waveform. An approximately trapezoidal-shaped waveform current is energized in the concentrated winding of each phase. Even if the magnetic flux density is close to the maximum flux density of the soft magnetic member of the stator, large slot cross-sectional areas of the stator can be secured, thus outputting a large torque.

Provided are a topological circuit and a control strategy for driving a switched reluctance motor (SRM). In one aspect, an SRM has an N-phase winding structure, N=MK; the symmetrical K-phase windings in each set of symmetrical K-phase windings are connected in a star configuration; midpoints of M power switch bridge arms are connected to neutral points of M sets of symmetrical K-phase windings in one-to-one correspondence; and K output terminals of M K-phase inverters are connected to lead-out terminals of the M sets of symmetrical K-phase windings in one-to-one correspondence. In another aspect, an SRM has N phases of windings connected in a star configuration; a midpoint of an additional bridge arm is connected to a neutral point for the N phases of windings; midpoints of N inverter bridge arms are connected to lead-out terminals of the N phases of windings in one-to-one correspondence.