Research On Sensorless Control For Hybrid Excited Machine In Low Speed

Compared with permanent magnet synchronous machines(PMSMs),the permanent magnet(PM)and field winding are both existed in the hybrid excited machines.The air gap magnetic field is jointly determined by the excited magnetomotive force and the PM magnetomotive force,which achieves the ability to adjust the air gap magnetic field.In order to realize the sensorless control of the hybrid excited machine in the low speed region,this paper proposes a high-frequency(HF)signal injection method which does not rely on the saliency of rotor,and analyzes the performance of initial position detection.The main research contents of the thesis are shown as follows:Firstly,a 12-slot,10-pole hybrid excited switched flux permanent magnet(HESFPM)machine is used as the control object.The topology and operation principle of machine are briefly introduced.The mathematical model of the hybrid excited machine in the stationary coordinate system and the rotating coordinate system are analyzed,and the priniciples of SVWPM control and excitation current adjustment are introduced.Secondly,in order to solve the problem of the traditional sensorless control method of HF signal injection which relies on the saliency of the rotor,a sensorless control method with HF signal injection in field winding is proposed.In the HESFPM machines,the flux-linkage produced by the field excitation is always aligned with the d-axis,the injected HF pulse signal in the field winding can only induce the HF current signal in the actual d-axis.Based on this principle,the estimated rotor position will align with the actual rotor position once the HF current signal in the estimated q-axis is converged to zero.The analysis shows that proposed method is related to the mutual inductance between the field winding and the armature winding instead of the saliency of rotor.Then,the method of detecting the initial position is further explored based on HESFPM machine.The proposed initial position detection method based on HF signal injection in field winding can directly estimate the rotor position to the real value by using the mutual inductance between the field winding and the armature windings.Compared with the traditional method based on HF signal injection in d-axis,the step of judging the polarity of the magnetic pole is omitted.At the same time,this paper proposes an initial position detection method based on numerical analysis.This method injects a pulse signal into the field winding,which can directly calculate the rotor position by sampling the armature current.Finally,a HESFPM machine drive platform was built based on the dSAPCE system,the effectiveness of the sensorless control method at low speed and the rotor initial position detection method were verified.The experimental results show that proposed sensorless control method with HF signal injection in field winding does not rely on the saliency of rotor and show good dynamic and steady-state performance.The proposed initial position detection methods based on field winding signal injection and numerical analysis can effectively detect the initial position of the rotor.