Research On Direct Torque Control For Dual Three-Phase Salient Pole Permanent Magnet Synchronous Motor With Concentrated Winding

Dual three-Phase Permanent Magnet Synchronous Motor is a kind of motor with a relatively rapid development.It has the characteristics of simple structure,high output,large voltage range and high efficiency,It has been widely used in the fields of marine electric propulsion system,electric locomotive traction system,rail transit propulsion system and so on.Multi-phase permanent magnet synchronous motor drive system has the advantages of multi-degree of freedom control,so its drive system running reliability,even if the motor winding phase loss or inverter bridge fault,can still rely on the remaining control degrees of freedom to achieve fault-tolerant motor operation.Among them,the dual three-phase permanent magnet synchronous motor is a typical multi-phase motor,this paper studies the direct torque control,improving torque by injecting harmonics and fault tolerant control strategy of the motor.In this thesis,Ansoft/Maxwell finite element analysis software is firstly used to analyze the design structure and connection rules of dual three-phase permanent magnet synchronous motor.The simulation test is carried out to the motor,and compared with the actual measurement results of the prototype to verify its correctness.Analysis of the winding back EMF contains a higher proportion of the third and fifth harmonic,and the back-EMF into a trapezoidal wave.Then,the corresponding harmonic plane mapped by the transformation matrix is expounded,and the mathematical model of dual three-phase permanent magnet synchronous motor in natural coordinate system,stationary coordinate system and rotating coordinate system is constructed.Under the premise of the direct torque control strategy of dual three-phase permanent magnet synchronous motor,the torque and flux linkage hysteresis control structure is adopted,and the harmonic content is effectively suppressed without adding any other control module.Combined with the proposed control strategy,the voltage vector on the fundamental wave plane can be used to control the torque and flux linkage to achieve the stable operation of the motor.For the neutral connected dual three-phase permanent magnet synchronous motor,the winding back EMF contains a higher proportion of the three and fifth harmonics,how to use the output voltage vector of the six-phase inverter to build a dual electromagnetic torque and stator flux linkage in the fundamental plane and the fifth harmonic plane at the same time,and to use the electromagnetic torque in five planes to enhance the load of the motor ability.By harmonic injection to increase the torque,select the optimal switch vector table,to achieve the fundamental torque,flux and the fifth harmonic torque,flux control at the same time.Thanks to dual three-phase motor belongs to six-phase motor,a direct torque control system of phase A lacking in dual three-phase permanent magnet synchronous motor based on the mathematical model of fault-free system is proposed.Taking into account the back EMF into a trapezoidal wave,the corresponding harmonic plane will have the corresponding harmonic torque,and the torque ripple will be generated when the motor is running.In this regard,through the remaining five-phase inverter output voltage vector,the direct torque control method of total torque torque hysteresis and fundamental plane hysteresis loop is established.The controllable part is used to control the torque ripple of the harmonic output,To achieve fault-tolerant direct torque control with opened a phase.To verify the control strategy proposed in this paper,Through MATLAB/Simulink simulation and a set of TMS320F2812 DSP as the core of the direct torque control hardware system,the feasibility and effectiveness of the system are verified.