Research On Starting Control Strategy Of Five-phase Permanent Magnet Synchronous Motor For Integrated Starter/Generator

The integrated starter and generator system integrates the function of starter and generator,and has been widely used in aviation aircraft.The permanent magnet synchronous motor has large starting torque,good control performance,and high power density,it has advantages in medium and low speed occasions.Applying permanent magnet synchronous motor integrated starter and power generator system to a launch vehicle can reduce the amount of primary energy carried by the launch vehicle,eliminate the starter gas cylinder carried by the starter oxygen pre-compression pump,and reduce the complexity of the ground test system.The start-up power of the integrated starter-generator system is equivalent to the generated power,but the start-up stage has a low speed and a large torque,while the generation stage has a high speed.In order to meet the characteristics of the starting and power generation phases under the severe space and weight constraints of the launch vehicle,taking into account the high reliability requirements of the launch vehicle,this paper studies the mathematical model of the built-in non-sinusoidal five-phase open-winding permanent magnet synchronous motor,the working principle of the integrated start-up and power generation system,the start-up control strategy to improve the torque density of the system,the dual-space closed-loop fault-tolerant control strategy and the integrated start-up and power generation experimental platform.First,this paper analyzes the structural characteristics of the built-in non-sinusoidal five-phase open-winding permanent magnet synchronous motor and the working principle of the integrated starter and generator system,and establishes the mathematical model of the motor in the natural coordinate system and the rotating coordinate system.It can be obtained that the key to improving the torque density of the system is to make full use of each torque component.Fault-tolerant control needs to control the fundamental wave space and the third harmonic space at the same time to suppress the harmonic torque caused by the motor structure.Secondly,the starting control strategy of the integrated system of starting and generating is researched.The third harmonic current injection method that minimizes the amplitude of the phase current is studied,using the third harmonic torque and the optimal superposition relationship between the third harmonic and the fundamental current.The problem of directly injecting the third harmonic current in equal proportions based on the maximum torque/current ratio control strategy is analyzed.A starting control strategy for the maximum torque/current ratio considering the harmonic space is proposed,which solves the problem of directly combining the maximum torque/current ratio control strategy and the harmonic current injection strategy,that is,the third harmonic current and the fundamental current cannot be optimal Overlay.A simulation model is built and the proposed starting control strategy is simulated and verified.It proved that the maximum torque/current ratio starting control strategy considering the harmonic space can reduce the phase current amplitude by15% when the torque is 40N·m,Can make full use of reluctance torque,harmonic torque and harmonic current to improve the torque density of the system.Thirdly,the fault-tolerant control strategy of the five-phase open-winding permanent magnet synchronous motor is researched.Without the constraint of the sum of phase currents being zero,the fault-tolerant current expressions for decoupling the fundamental wave space and the third harmonic space are derived based on the principle that the magnetomotive force remains unchanged.The non-positive five-phase open-winding permanent magnet synchronous motor with a built-in structure needs to control the fundamental wave space and the third harmonic space at the same time.Using the remaining four control degrees of freedom after a phase is open,and based on the obtained fault-tolerant current,a dual-space closed-loop fault-tolerant control strategy is proposed.Its decoupling matrix does not need to be reconstructed.Finally,an integrated starter and power generation experiment platform is built,which is mainly composed of a load motor system,a five-phase open-winding permanent magnet synchronous motor and its control driver,etc.The start-up control strategy and fault-tolerant control strategy proposed in this paper are further verified through experiments.They are feasible and effective.