This invention proposes a method to regulate high efficiency region of permanent magnet motor. The internal relationship between the point with maximum efficiency and the points around it is firstly revealed. Then, the optimal combination of copper loss, iron loss and permanent magnet eddy-current loss is presented when maximum efficiency point moves toward different directions. Hence, the method for regulating high efficiency region can be obtained. This method can be suitable for any type of permanent magnet motors, which can adjust high efficiency region to the dense working point area of the motor under different operating conditions according to design requirements. If this method is used into electric vehicle, it can combine the high efficiency region with the electric vehicle driving cycle to reduce energy consumption and enhance the life mileage of electric vehicle effectively.

A system and method for controlling a six-phase machine include generating a plurality of control vectors for the six-phase machine. The six-phase machine is configured as a combination of a first three-phase machine and a second three-phase machine. Each of the plurality of control vectors is generated by combining two phase vectors from the six-phase machine, where one phase vector is selected from the first three-phase machine and another phase vector is selected from the second three-phase machine. The system and method also include implementing a control method based on the plurality of control vectors to control the operation of the six-phase machine.

A food processor and a rotational speed increase control method and apparatus therefor. The rotary speed increase control method comprises the following steps: when the food processor is idle or in a light load state, obtain a rotational speed instruction, analyze the rotational speed instruction to acquire a target rotational speed for a drive motor, and generate a PWM control signal according to the target rotational speed to control the drive motor, during the process of controlling the drive motor, gradually increase the duty cycle of the PWM control signal according to a progressive increment mode until the duty cycle of the PWM control signal reaches 1; and carry out weak magnetic control on the drive motor to quickly increase the rotational speed of the drive motor.

A motor control apparatus includes: a high-pole-number controller that generates a voltage command for high-pole-number drive of an electric motor and controls operation of the electric motor under the high-pole-number drive; a low-pole-number controller that generates a voltage command for low-pole-number drive of the electric motor and controls operation of the electric motor under the low-pole-number drive; and a priority pole-number determiner that determines which one of the high-pole-number drive and the low-pole-number drive is to be given priority during switching between the high-pole-number and low-pole-number drives. Moreover, during the switching, of the high-pole-number and low-pole-number controllers, the controller corresponding to the drive given priority by the priority pole-number determiner calculates the voltage command for the drive given priority; and the controller corresponding to the drive not given priority calculates, based on the voltage command for the drive given priority, the voltage command for the drive not given priority.

A driving device includes a connection switching unit to switch a connection state of coils between a first connection state and a second connection state in which a line voltage is lower than in the first connection state, a controller to control a motor and the connection switching unit, and a rotation speed detector to detect a rotation speed of the motor. When the connection state of the coils is the first connection state and the rotation speed detected by the rotation speed detector becomes higher than or equal to a first rotation speed, the controller causes the motor to rotate at a second rotation speed higher than the first rotation speed, and then causes the connection switching unit to switch the connection state of the coils from the first connection state to the second connection state.

A motor device for a vehicle includes a stator, a rotor, a bearing, an inverter, and a controller. The stator is attached into a housing and includes a concentrated winding coil. The rotor includes a permanent magnet. The bearing supports a rotating shaft of the rotor. The inverter controls an energization state of the concentrated winding coil. If a rotational speed of the rotor is greater than a threshold, the controller outputs a control signal to the inverter to execute field weakening control, and thereby makes a potential difference between the housing and the rotating shaft lower than a withstand voltage of the bearing. The control signal controls the energization state of the concentrated winding coil. The field weakening control generates magnetic flux of the concentrated winding coil in a direction of weakening magnetic flux of the permanent magnet.

The invention relates to a method and device for operating an electric machine (10) for outputting a predefined torque and a predefined rotational speed, comprising the following steps: providing (420) a first and a second operating mode for the operation of the electric machine (10); detecting (430) a temperature of the electric machine (10); and operating the electric machine (10) in the first operating mode (440) if the detected temperature falls below a threshold value, and operating the electric machine (10) in the second operating mode (450) if the detected temperature corresponds with the threshold value or exceeds same. During the operation of the electric machine (10) in the second operating mode (450), with the resulting output of the predefined torque and the predefined rotational speed, the magnetic stator flux of the electric machine (10) is reduced compared with the magnetic stator flux of the electric machine (10) during the operation of the electric machine (10) in the first operating mode (440), with the resulting output of the predefined torque and the predefined rotational speed.

An apparatus, such as an adjustable frequency drive (AFD), includes an inverter configured to be selectively coupled to a motor in a first mode and an AC line in a second mode and a control circuit configured to operate the inverter as a motor drive in the first mode and as a power compensator in the second mode. The power compensator may provide power factor correction. The control circuit may include a scalar controller configured to control the inverter according to a voltage vs. frequency characteristic determined by a field weakening point reference and the control circuit may vary the field weakening point reference in the second mode. The inverter may have an input coupled to a DC bus and the control circuit may be configured to adjust a frequency of the inverter in the second mode to increase a voltage on the DC bus.

A driving device includes a connection switching unit to switch a connection state of coils between a first connection state and a second connection state in which a line voltage is lower than in the first connection state, a controller to control a motor and the connection switching unit, and a rotation speed detector to detect a rotation speed of the motor. When the connection state of the coils is the first connection state and the rotation speed detected by the rotation speed detector becomes higher than or equal to a first rotation speed, the controller causes the motor to rotate at a second rotation speed higher than the first rotation speed, and then causes the connection switching unit to switch the connection state of the coils from the first connection state to the second connection state.

A power tool includes a brushless motor, a supplying circuit, and a controller. The brushless motor is configured to drive and rotate when a voltage applied to the brushless motor is larger than or equal to an induced voltage. The supplying circuit is configured to apply a driving voltage to the brushless motor. The controller is configured to control the supplying circuit. The supplying circuit includes a rectifying circuit, a capacitor, and a switching circuit. The rectifying circuit is configured to rectify an alternating voltage and output a rectified voltage. The capacitor is configured to smooth the voltage inputted via the rectifying circuit. The switching circuit is configured to perform a switching operation based on a PWM signal to adjust a period during which the driving voltage is applied. The controller is configured to set a duty ratio within a prescribed range, and output the PWM signal of the set duty ratio to the switching circuit to control the switching operation. The controller is configured to perform a constant-number-of-rotation control for controlling the brushless motor to rotate at a target rotation number by changing the duty ratio. The capacitor has a capacitance allowing a smoothed voltage to be always larger than or equal to the induced voltage during the constant-number-of-rotation control.