Research On Key Technologies Of Position Sensorless And Hybrid-fault-tolerant Control For Interior Permanent Magnet Synchronous Motor Drives

Thanks to its outstanding features of high efficiency,strong overload capacity and simple structure,interior permanent magnet synchronous motor(IPMSM)gained extensive attention and research from domestic and foreign scholars.As the connecting bridge of the controller and the motor,position sensor,current sensor and inverter are the most important three key components.The damage or absence of these key devices will result in the unreachability of the high performance and high efficiency closed-loop control of the drive,which should be studied carefully.In order to solve the aforementioned problems,in this paper,the fault-tolerant and hybrid-fault-tolerant control strategies of the above key components are studied.The corresponding control strategies are also put forward to promote the fault-tolerant capability of the drive under complex fault conditions.The position detection methods are studied in the paper first,where two strategies based on rotational high frequency voltage injection methods are proposed for different system requirements.The first method makes use of the relationship between the rotor position and the amplitude of the three-phase high frequency currents,which shows the advantages of fast detection and small computational complexity.The second one utilizes the phase angle differences of the positive and negative sequence components of the high frequency currents,which shows higher detection precision,in spite of the slightly increased calculation amount.Then,the paper studies the control method under fault or missing of both the three-phase current sensors and the position sensor.A hybrid-fault-tolerant control strategy is proposed to solve the aforementioned issue.In the proposed strategy,a new vector synthesis method are proposed for the purpose of phase current reconstruction,which also satisfies the minimum action time requirements of the basic vectors.Also,the output voltage range with the proposed vector generating method is a constant region,which does not need to recalculate in each PWM cycle.With the method of "rotation change of ?-? coordinate system" proposed in this paper,the vector synthesis and basic vector action time calculation methods can be generalize from sector I to the other sectors without complex conversion,thus greatly saving the memory demand and calculation of the microprocessor.Afterwards,the paper studies the hybrid-fault-tolerant control strategy under both the open circuit fault of a single bridge arm and the position sensor fault.A vector synthesis method based on the proposed nonorthogonal-nonlinear k-l axis coordinate system in the three-phase four-switch inverter is proposed in this paper.With the proposed method,the output voltage vector can be equivalent to the sum of the two basic voltage vectors only by simple mathematical transformation.The proposed method has the advantages of simple algorithm and small calculation.The paper also studies the hybrid-fault-tolerant control strategy under both the open circuit fault of a single bridge arm and fault of the position sensor and phase current sensors.The proposed strategy realizes the effective control of the IPMSM in the single current sensor based three-phase four-switch inverter drive,and also realizes the detection of the rotor position.Compared with the vector synthesis method with all the three-phase current sensors installed,the proposed method only needs small modification in the phase current reconstruction dead zones,while in the larger "Current Reconstruction Normal Area" no change is made to the vector generation method.Therefore,the proposed method reduces the amount of computation of phase current reconstruction in the vector synthesis process,and lightens the burden of the microprocessor.Finally,the paper analyzes the errors in the phase current reconstruction strategies,point ing out the causes of these errors,and puts forward a solution.According to the causes of this inherent error,the paper divides the aforementioned errors into two categories: "the error of the non decoupling phase current reconstruction strategy" and the "phase current reconstruction error caused by the instantaneous sampling instead of the average current".In this paper,a compensation strategy based on the "rate of change" estimation of the three-phase current is proposed.The estimation of the average values of phase currents in the "PWM period" can be realized by using the values of the limited sampling points.