Permanent magnet synchronous motor direct torque control method enabling constant switching frequency
A technology of permanent magnet synchronous motor and direct torque control, which is applied in torque ripple control, motor generator control, electronically commutated motor control, etc., and can solve the problems of unstable switching frequency, high cost requirements, and large torque ripple, etc. problem, achieve the effect of reducing flux linkage and torque ripple
Active Publication Date: 2018-05-29
SOUTHEAST UNIV
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Problems solved by technology
[0003] At present, the speed controller of permanent magnet synchronous motor often adopts vector control and traditional direct torque control. Vector control requires accurate rotor position. Although the control accuracy is high, it has poor robustness and high cost requirements; although direct torque control is Strong rod, but the switching frequency is not constant and the torque ripple is large at low speed, which has certain limitations
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[0019] Such as figure 1 As shown, the torque and flux linkage closed-loop control consists of permanent magnet synchronous motor, speed sensor, power conversion circuit, speed PI regulator, torque PI regulator, stator flux and torque calculation, switch table, duty ratio calculation and The PWM generation module is composed. The three-phase stator currents ia, ib, and ic are measured by current sensors, and then enter the stator flux linkage estimation module, combined with the basic voltage vector U selected by the switch table x , U y and duty cycle D x 、D y Calculate the stator flux ψs and torque Te, the estimated stator flux and torque are fed back to the torque and flux closed-loop respectively as feedback quantities, and the two closed-loop output duty ratios D f 、D T , the estimated stator flux angle θs is used to judge the sector where the stator flux is located, combined with the closed-loop output D f 、D T To select the voltage vector, the duty ratio calculati...
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The invention discloses a permanent magnet synchronous motor direct torque control method enabling constant switching frequency. According to the method, two basic voltage vectors are selected from anoptimized switching table according to the signs and magnitudes of a duty cycle Df and a duty cycle DT which are outputted by two inner loops and the angle information of a stator flux linkage; the duty cycle Df and duty cycle DT of a flux linkage axis are corrected according to the angle information of the stator flux linkage; and the duty cycle Dy of the y-axis voltage component Uy of a torqueaxis, the duty cycle Dx of the x-axis voltage component Ux of the flux linkage axis and the duty cycle D0 of a zero vector are obtained after normalization processing is performed. According to the method of the present invention, the torque closed-loop and the flux linkage closed-loop which directly output duty cycles, and the optimized switching table are adopted, and therefore, the method of the present invention can assist in solving the problem of the inconstant switching frequency of conventional direct torques and the problem of large ripple of low-rotation speed torques compared with the prior art; and since the duty cycles are corrected, and flux linkages and torque ripples are further reduced.
Description
technical field [0001] The invention relates to a motor torque control method, in particular to a constant switching frequency permanent magnet synchronous motor direct torque control method. Background technique [0002] Permanent magnet synchronous motor has the characteristics of simple structure, small size, high operating efficiency, high power factor, small moment of inertia, etc. It is widely used in aerospace, CNC machine tools, electric vehicles and other fields. [0003] At present, the speed controller of permanent magnet synchronous motor often adopts vector control and traditional direct torque control. Vector control requires accurate rotor position. Although the control accuracy is high, it has poor robustness and high cost requirements; although direct torque control is Strong rod, but the switching frequency is not constant and the torque ripple is large at low speed, which has certain limitations. Contents of the invention [0004] Purpose of the inventi...
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IPC IPC(8): H02P21/30H02P6/10
CPCH02P6/10H02P21/30
Inventor 樊英李令张丽
Owner SOUTHEAST UNIV