38results about How to "Reduce electromagnetic torque ripple" patented technology

The invention relates to a one-phase-failure fault-tolerant torque control method of a 60-degree offset six-phase permanent magnet synchronous motor. The method includes the steps that currents from ib to if of the remaining healthy phases and the position angle of a rotor are acquired; the currents ib to if of the remaining five healthy phases are transformed into i5alpha, i5beta, i5z1, i5z2 and i5z3; the virtual stator currents iz5alpha and iz5beta are calculated; the virtual stator flux linkages psiz5alpha and psiz5beta are worked out; the serial number thetai of the virtual stator flux linkages psiz5alpha and psiz5beta on the alpha and beta plane sector is judged; the variable phi for controlling the virtual stator flux linkage amplitudes is output; the electromagnetic torque (please see the symbol in the specification) is calculated; the electromagnetic torque control variable tau is output; the zero-sequence current error vector (please see the symbol in the specification) is output; the zero-sequence current error vector, the tau, the phi and the thetai are sent to an optimum switch vector table to obtain an optimum switch combination, the optimum switch combination further acts on windings of the remaining five healthy phases to achieve the control target that the zero-sequence current, the virtual stator flux linkage amplitudes and the electromagnetic torque error are zero. Through the control method, a direct torque control driving system of the 60-degree offset six-phase permanent magnet synchronous motor can continue running after one phase of the motor fails or one phase of an inverter bridge fails.

The invention relates to a fault-tolerant direct torque control method for a six-phase permanent magnet synchronous motor lacking any two phases of windings. The method includes the steps that remaining healthy phase currents from ic to if and a rotor position angle are collected; the remaining healthy four phases of currents from ic to if are converted into isalphaisbeta and iszlisz2; virtual stator currents ixsalphaixsbeta are calculated; a virtual stator flux linkage psixsalphapsixsbeta is calculated; the number thetaxsi of an alphabeta plane sector where a vector of the virtual stator flux linkage psixsalphapsixsbeta is located is judged; a variable phi for controlling the amplitude of the virtual stator flux linkage is output; an electromagnetic torque Te is calculated; a variable tau for controlling the electromagnetic torque is output; a zero-sequence current error delta isz is output; delta isz, tau, phi and thetaxsi are sent to an optimal switch vector table so that an optimal switch combination can be obtained, and the optimal switch combination acts on remaining four healthy phases of windings so that the control target that the error of zero-sequence currents, the amplitude of the virtual stator flux linkage and the electromagnetic torque is zero can be achieved. The control method solves the problem of how to make a 60-degree-bias six-phase permanent magnet synchronous motor direct torque control drive system continue to operate when two phases of the windings of the motor are disconnected or two phases of windings of an inverter bridge break down.

The invention discloses a motor rotor and a motor with the same. The motor rotor comprises a main body and multiple steel magnets, wherein the main body is provided with a rotor hole and multiple steel magnet grooves encircling the rotor hole; the outer profile of the main body comprises a plurality of concentric arc sections concentric with the rotor hole and connecting line segments connected between adjacent concentric arc sections; the concentric arc sections are in one-one correspondence with the steel magnet grooves in the radial direction respectively; each connecting line segment comprises one or more straight line segments; the included angle beta between the central normal line of each straight line segment and the connected line of the midpoint of the central normal line and the center of the rotor hole is not smaller than 0 degree and not greater than 20 degrees; at least one steel magnet is arranged inside each steel magnet groove. According to the motor rotor provided by the embodiment of the invention, the outer profile of the main body comprises the concentric arc sections and connecting line segments connected between adjacent concentric arc sections, so that the reduction of the counter potential harmonic content of the motor is facilitated, and the cogging torque pulsation and electromagnetic torque pulsation of the motor are reduced.

The invention discloses a doubly-fed wind generator stator and rotor magnetic linkage synchronous flux-weakening control method under power grid failure. When the voltage of the power grid has faults, the high-control-frequency stator and rotor magnetic linkage synchronous flux-weakening control method is adopted by a doubly-fed wind generator rotor side converter. All of the variables of the control method are on the basis of a two-phase synchronous rotating coordinate, when faults occur, a rotor magnetic linkage can be adjusted through the control of the rotor side converter, the synchronous control of the rotor magnetic linkage and a stator magnetic linkage can be realized, the fault impact of the stator magnetic linkage to the rotor magnetic linkage can be weakened, and the rotor fault overcurrent can be reduced. The method can control the rotor fault current be 1.5-1.6 times of the rated current, reduces the electromagnetic torque ripple during the failure, the impact to a set during the failure, and the active power and reactive power fluctuation of the stator side, and can effectively improve the fault ride-through capability of the doubly-fed wind generator under power grid voltage failure.

The invention discloses a method using non-uniform stator slots to inhibit the cogging torque of a permanent magnet synchronous motor. Under the condition that the size of stator teeth does not change, center positions of stator slots rotate and deviate in the circumferential direction of a stator. The method is simple in technique and easy for implementation and does not need to increase any extra machining step. The coupling influence of the offset angles of the stator slots and other parameters of the motor is small, and thus the offset angles can be designed independently. While reducing the cogging torque of the motor, the method can also improve the counter electromotive force waveform of the motor, reduce electromagnetic torque fluctuation, avoid asymmetric phenomena of three-phase windings due to non-uniform slot distribution, and effectively improve the overall performance of the motor.

The invention discloses a doubly-fed wind power generator quick weak magnetic control method. In a steady state, all variables are based on a two-phase synchronous rotating coordinate system. The change in active power and the change in reactive power of a stator in a sampling period are predicted; then, the power in the next sampling period is compensated; and finally, the rotor voltage is calculated, and PWM modulation is conducted. By adopting the method, the fluctuation of active power and reactive power of the stator is reduced. When the grid voltage drops, all the variables are based on a two-phase static coordinate system. Quick weak magnetic control on rotor flux is realized through a rotor voltage prediction model, coordinate transformation is performed on the predicted rotor voltage under the two-phase static coordinate system to obtain the rotor voltage under a two-phase rotor speed rotating coordinate system, and finally, PWM modulation is conducted. Through quick weak magnetic control, the rotor current can be controlled within 1.5-1.6 times of the rated current, and the electromagnetic torque ripple is small in the fault period. The operation capacity of a doubly-fed wind power generator in fault is improved.

The invention discloses a fault operation method under doubly-fed wind power generator stator and rotor flux weak magnetic control. The technical scheme is as follows: when the grid voltage runs stably, a doubly-fed wind power generator rotor-side converter adopts vector control based on stator flux orientation, and when the grid voltage runs in fault, the doubly-fed wind power generator rotor-side converter performs stator and rotor flux weak magnetic control, and the control frequency of stator and rotor flux weak magnetic control is twice that of vector control based on stator flux orientation. No complex coordinate transformation is needed in the fault period, and quick response to a fault is realized. The rotor current can be controlled within 1.5-1.6 times of the rated current. The electromagnetic torque ripple is small. The fluctuation of active power and reactive power at the stator side is small. The operation capacity of a doubly-fed wind power generator in fault is improved.

The invention provides a single-phase capacitor-operated motor, comprising a motor shaft, a rotor, a stator, a front end cover and a rear end cover; wherein, the rotor is sheathed on the motor shaft and the stator is sheathed at the outer side of the rotor; mutually snap-fit front end cover and rear end cover are arranged at the outer side of the stator; the two ends of the motor shaft are installed on the front end cover and rear end cover via bearings; a stator core of the stator is provided with double-row grooves including a deep-row groove and a shallow-row groove; stator winding is concentrated winding comprising first winding and second winding; coils of the first winding and the second winding are respectively wound in the deep-row groove and the shallow-row groove of the stator core; the adjacent coils of the first winding, which are wound in the deep-row groove, are wound forward and reverse; the adjacent coils of the second winding, which are wound in the shallow-row groove, are wound forward and reverse; the first winding is in parallel connection with the second winding after series connection with capacitance or the second winding is in parallel connection with the first winding after series connection with capacitance. The single-phase capacitor-operated motor can save wires by about 20%; motors with thin iron core and large winding span witness more obvious saving of copper content for windings; in addition, the winding shortens the axial length of the motor; manufacturing of the stator winding achieves machine winding, simplifies the processing flows and improves the production efficiency of the stator; besides, the concentrated stator winding adopted by the invention has high coefficient and good motor property and is suitable for motors with different poles and power.

The invention relates to an independent wheel traction hub motor for a railway vehicle. The independent wheel traction hub motor comprises a stator, a rotor, an unequal-width unequal-thickness Halbachaxial annular part segmented permanent magnet array, a rotating shaft and an armature winding, wherein the rotor is installed in the stator, the rotor is fixed on the rotating shaft, the armature winding is installed on the stator, the unequal-width unequal-thickness Halbach axial annular part segmented permanent magnet array is installed on the rotor and located between the rotor and the stator,each magnetic pole is composed of three permanent magnets with the same polarity, and the permanent magnets adopt a Halbach magnetizing mode. The three permanent magnets comprise a main magnetic poleand two boundary magnetic poles, the main magnetic pole is of an axial annular part segmented structure, and the two boundary magnetic poles are located on the two sides of the main magnetic pole andare unequal to the main magnetic pole in width and thickness. The unequal-width unequal-thickness Halbach axial annular part segmented permanent magnet synchronous motor is applied to the interior ofa hub, the harmonic distortion rate of an air gap magnetic field is small, the utilization rate of permanent magnets is high, the torque pulsation is low, and the eddy current loss of the permanent magnets is small.

The invention discloses a low-noise permanent magnet direct current motor. The invention aims to solve the technical problem that a conventional permanent magnet direct current motor is high in noise when working. The low-noise permanent magnet direct current motor comprises a shell and a rotating shaft, wherein one end of the rotating shaft extends out of the shell, the shell is internally provided with a commutator fixed on the rotating shaft and a carbon brush which is in contact with the commutator to transmit current, the inner side face of the carbon brush comprises an axial arc face and a connecting inclined face which are axially connected, one end of the connecting inclined face is connected with the axial arc face, the other end of the connecting inclined face inclines towards the outer side of the shell and is connected with the end face of the carbon brush, and the axial arc face is in face-to-face contact with the peripheral face of the commutator.

The invention discloses a bilateral filtering permanent magnet synchronous motor driving device adopting SiC MOSFETs, and relates to the technical field of power electronics, and the technical schemeis that the bilateral filtering permanent magnet synchronous motor driving device comprises a three-phase power grid, an LCL filter, a rectifier, a DC bus, an inverter, an LC filter, a long-line cableand a permanent magnet synchronous motor which are connected in sequence; the rectifier and the inverter adopt SiC MOSFETs which are high in switching speed and low in loss as power switching devices. The beneficial effects of the invention are as follows: the SiC MOSFET which is high in switching speed, low in switching loss, small in conduction resistance and high in working temperature is usedas a power switching device. The switching frequency of the driving device can be increased to 50 kHz or above, so that the weight and size of the LCL and LC filters are reduced, the system control precision is improved, the efficiency of the driving device is improved, the working temperature of the driving device is increased, and the cooling link is simplified.

The invention discloses a decoupling method of a wound-rotor bearingless asynchronous motor. The decoupling method comprises a three-phase winding equivalent inductance parameter calculation method, avoltage equation and flux linkage equation construction method and a motor electromagnetic torque and suspension force independent control strategy based on magnetic field orientation. The method comprises the following steps: establishing an inductance matrix of the wound-rotor bearingless asynchronous motor and simplifying the inductance matrix by adopting an equivalence principle; deducing a voltage equation and a flux linkage equation of the motor; and finally, adopting a vector control strategy of torque magnetic field orientation and air gap magnetic field orientation to decompose the original system into two subsystems capable of independently controlling the rotating speed and the flux linkage of the motor. On the basis of establishing an accurate mathematic model of the wound-rotor bearingless asynchronous motor, the purpose of completely decoupling the rotating speed and the flux linkage is achieved by adopting the vector control principle of coordinate transformation and magnetic field orientation, and finally independent control over the electromagnetic torque and the suspension force of the wound-rotor bearingless asynchronous motor is achieved.

The invention discloses an asynchronous motor control method based on an MRAS. The method comprises the steps of acquiring a three-phase stator current and voltage of an asynchronous motor, and generating a torque current feedback quantity and exciting current feedback through Clark and Park conversion in sequence; acquiring a rotor angular speed feedback quantity through an improved MRAS, outputting a torque current after a difference value between the rotor angular speed feedback quantity and a preset rotating speed is adjusted through a speed controller, and outputting a first voltage afterthe difference value between the torque current and the torque current feedback quantity is input into a first PI adjuster; inputting the difference value between a preset exciting current and an exciting current feedback quantity into a second PI regulator and then outputting a second voltage; carrying out Park inverse transformation on the first voltage and the second voltage to generate a two-phase control voltage sum, and inputting the two-phase control voltage sum into SVPWM to be modulated into PWM modulation waves; and controlling a three-phase full-bridge inverter switching device through the PWM modulation waves, and controlling operation of an asynchronous motor. In the invention, low-speed stability of the asynchronous motor is improved, and an electromagnetic torque ripple isreduced.

The invention discloses an 18-phase wind power generation system and a control method thereof. The wind power generation system includes an 18-phase permanent magnet synchronous generator, 18 single-phase bridge-type full-control rectifiers and 18 power electronic transformers; Each phase winding of the synchronous generator is rectified by a single-phase bridge fully-controlled rectifier and then passed through a power electronic transformer. The secondary output terminals of all power electronic transformers are cascaded and connected to the high-voltage DC grid. The invention replaces the traditional three-phase motor with an 18-phase permanent magnet synchronous generator. Compared with the traditional three-phase generator, the power transmitted by the 18-phase permanent magnet synchronous generator is larger; at the same time, more phase windings ensure that the 18-phase The permanent magnet synchronous generator can still effectively transmit power when the winding part is broken, and has high fault tolerance; and, under the action of the stator harmonic current, the electromagnetic torque of the 18-phase permanent magnet synchronous generator The lower pulsation greatly improves the reliability of the 18-phase permanent magnet synchronous generator during operation.