A high-voltage permanent magnet frequency conversion all-in-one machine according to an embodiment of the present disclosure includes a frequency converter configured to perform frequency conversion on a high-voltage alternating current, and output at least three alternating currents, a permanent magnet motor configured to receive the alternating currents subjected to the frequency conversion and output from the frequency converter, to drive the motor to operate, and a controller configured to control the frequency converter to perform the frequency conversion on the high-voltage alternating current, and control an operation state of the permanent magnet motor.

A dual-rotor in-wheel motor based on an axial magnetic field and a control method thereof are provided. The dual-rotor in-wheel motor includes an axle and a hub. The axle is fixedly connected to a frame. The hub relatively rotates around the axle. A disc-shaped intermediate stator is fixedly connected on the axle. A left coil assembly and a right coil assembly are fixedly mounted on two sides of the intermediate stator, respectively. A left rotor and a right rotor are respectively arranged on the two sides of the intermediate stator. The left coil assembly drives the left rotor to rotate, and the right coil assembly drives the right rotor to rotate. A left clutch is arranged between the left rotor and the hub, and a right clutch and a speed reduction mechanism are arranged between the right rotor and the hub.

A control device 60 includes: a PWM generation unit 63 that outputs a PWM drive signal to an inverter 40; and a torque limiting unit that outputs a post-limitation torque command to the PWM generation unit 63 based on a torque command from a higher-order control unit and a motor temperature. The torque limiting unit includes: a torque limiting factor calculation unit 61 that calculates a torque limiting factor based on the motor temperature; and a post-limitation torque calculation unit 62 that outputs the post-limitation torque command to the PWM generation unit 63 based on the torque command and the torque limiting factor. The torque limiting factor calculation unit 61 limits an output torque based on the motor temperature in a case where the motor temperature is higher than a predetermined temperature, and limits a torque to make the torque change more gently in a case where a rate of change over time in the motor temperature is larger than a predetermined value as compared with a case where the rate of change over time is equal to or smaller than the predetermined value.

Disclosed is a method for searching a MTPA curve of a vehicle permanent magnet synchronous motor based on a DC power, which includes a current closed-loop adjuster, a current command generator, a current command angle generator, an active power calculator, an active power storage and comparison processor and a current given vector corrector. According to the present disclosure, the tedious manual calibration is relieved, the optimal angle is automatically searched, and the production efficiency is improved; according to the present disclosure, the step size can be arbitrarily set according to the calibration requirements, so as to achieve a higher calibration accuracy.

A motor driving device includes: a connection switcher that has an electromagnetic contactor connected to a winding of a motor and switches connection condition of the winding by switching condition of the electromagnetic contactor; an inverter to apply an output voltage as an AC voltage to the winding via the connection switcher; a short-circuiting circuit having a rectification circuit and a switch; and a controller to control the electromagnetic contactor, the inverter and the switch, wherein a circulating circuit is formed by the short-circuiting circuit and the winding when the switch is set at ON, and the connection switcher switches the connection condition of the winding in a period in which the output voltage of the inverter is set at zero in a rotating operation of the motor and a current caused by the rotating operation circulates in the circulating circuit.

Described is a method of determining an initial rotor position on start-up of a synchronous motor. The method comprises applying at each of a plurality of pre-set motor angles a pair of voltage vector pulses, the pair of voltage vector pulses comprising a first and second pulses, each having the same amplitude but opposite polarities, the second pulse being applied immediately or near immediately after the first pulse. The method includes determining the stator current responses to said pairs of applied voltage vector pulses at said plurality of pre-set motor angles. Then, the initial rotor position can be determined from either of a stator angle corresponding to a pair of vector voltage pulses resulting in (a) a largest sum of stator currents or (b) where the sum of stator currents changes from a negative to a positive motor angle.

This application provides a permanent-magnet synchronous machine control method and device, and a permanent-magnet synchronous machine control system. The method includes: obtaining a d-axis current i.sub.d and a q-axis current i.sub.q in a permanent-magnet synchronous machine control loop at a current moment; obtaining a fifth-order harmonic current i.sub.d5th and a seventh-order harmonic current i.sub.d7th in the d-axis current i.sub.d in the permanent-magnet synchronous machine control loop at the current moment, and a fifth-order harmonic current i.sub.q5th and a seventh-order harmonic current i.sub.q7th in the q-axis current i.sub.q in the permanent-magnet synchronous machine loop at the current moment; determining a d-axis current i.sub.d.sup.k+1 at a next moment in each switch state; determining a q-axis current i.sub.q.sup.k+1 at the next moment in each switch state based on the first current i.sub.d.sup.k, the second current i.sub.q.sup.k, and the second voltage in each switch state; and determining a control policy of the permanent-magnet synchronous machine.

Described is a method of controlling operation of a synchronous motor. The method comprises, during constant power/speed motor operation, determining a value of a stator voltage (v.sub.s.sup.2) for an orthogonal rotating reference frame of the motor. Comparing the value of the determined stator voltage (v.sub.s.sup.2) to a threshold voltage (v.sub.s.sup.2.sub._max 1), said threshold voltage (v.sub.s.sup.2.sub._max 1) having a value between that of a maximum stator voltage (v.sub.s.sup.2.sub._max 0) for a basic speed mode of operation of the motor and that of a maximum stator voltage (v.sub.s.sup.2.sub._max 2) of the motor closed loop controller. If the determined value of the stator voltage (v.sub.s.sup.2) is greater than or equal to the value of the threshold voltage (v.sub.s.sup.2.sub._max 1), then controlling operation of the motor in a flux weakening mode of operation until a value of a current component (i.sub.d−Δi.sub.d) in a d-axis reaches a maximum negative value (−i.sub.d max), or until the value of the stator voltage (v.sub.s.sup.2) is less than the value of the threshold voltage (v.sub.s.sup.2.sub._max 1).

Provided is a magnetic pole position detection device with which it is possible to shorten the detection time of the initial magnetic pole position of the rotor of a synchronous motor. A magnetic pole position detection device that detects the magnetic pole position of the rotor of the synchronous motor, the magnetic pole position detection device comprising an excitation command unit that excites the synchronous motor while changing the current phase of the excitation current from a preset initial value, and a torque zero determination unit that determines whether the torque generated by the rotor has reached zero, the excitation command unit: continuously executing an operation for exciting the synchronous motor using, as the current phase of the excitation current, a value obtained with a subtraction process for subtracting, from the initial value, a phase angle corresponding to the cumulative value of the movement amount of the rotor from the starting point of excitation at the initial value of the current phase, during the period after the synchronous rotor was excited at the initial value of the current phase until the torque is determined to have reached zero; and acquiring, as the magnetic pole initial position, the value obtained with the subtraction process when the torque is determined to have reached zero.

A method for determining an initial rotor position of a permanent magnet synchronous motor (PMSM) includes: generating a plurality of transient currents by applying a plurality of voltages to each phase stator winding of a three phase stator winding of the PMSM; generating three phase current differences according to the plurality of transient currents; determining a first zone in which the initial rotor position of the PMSM is located according to the three phase current differences, wherein angles between 0-360 degrees are divided into a plurality of zones, and the first zone is selected from the plurality of zones; calculating three line current differences according to the three phase current differences; and determining the initial rotor position of the PMSM according to the first zone and the three line current differences.