Research On Control Technology For Single Rotor Frequency Conversion Compressor Of Permanent Magnet Synchronous Motor

Nowadays,the frequency conversion air-conditions have gradually gone into thousands of families,due to their superiorities in constant and comfortable temperature,energy conservation,small vibration and noise,rapid temperature regulation,well-adapted power grid voltage.The control performance of the compressor drive system mainly relies on their position/speed control precision,operation stability,speed adjustable range and anti-disturbance ability of power grid,etc.Therein,the low frequency torque ripple suppression and running performance,the high frequency flux-weakening control performance,as well as the whole frequency sensor-less control performance are the difficulties for frequency conversion compressor drive systems.This thesis has done a thorough research on the following three issues.First of all,the torque ripple suppression method of frequency conversion compressor in low frequency range is researched,which is able to reduce the speed ripple and then decrease the vibratory stress of compressor and pipeline,and extend the running range at low speed.Secondly,the high frequency running range has been extended by our proposed flux-weakening control strategy based on integrated SVPWM.Meanwhile,in order to improve the running stability of the flux-weakening control,extend the high frequency running range and achieve high-performance flux-weakening control,we have adopted the compensation algorithms of the stator resistance voltage drop and the inverter nonlinear distorted voltages,as well as the magnetic saturation suppression algorithm.Finally,a new sliding mode observer based on Lq mode has been investigated,which can lower the dependency of motor parameters,and the running stability of the whole frequency for compressor can be enhanced by combining the adaptive notch filter and quadrature phase locked loop technology.In order to inhibit the torque ripple and extend the low frequency range of frequency conversion compressor,we have done in-depth analysis on the speed wave reason of frequency conversion compressor in low frequency,and then proposed a PD type iterative learning control(PDILC)strategy with forgetting factor by utilizing the load torque cycle characteristics.Firstly,by means of the PDILC,the periodical speed wave of compressor has been reduced,and after the forgetting factor has been introduced into the algorithm,the error accumulation has been weaken which caused by non-periodic disturbance of compressor system.Simultaneously,the impact of the compressor torque temporal correlation on the speed wave suppression has been diminished by our optimized PDILC.Finally,the feedforward control also has implemented to realize the torque compensation of compressortorque,on the purpose of achieving speed fluctuation suppression effectively.For further inhibiting the low frequency torque ripple and ensuring the running stability,rapid tracking performance and anti-disturbance performance of compressor control system,we have put forwarded a speed ripple suppression strategy on optimized repetitive controller and disturbance observer in this paper.First of all,based on the zero phase error tracking controller(ZPETC)and q-type filter,we have proposed an optimized repetitive controller to realize rapid and accurate tracking,and enhance the stability of compressor system.Then,a compound strategy has been adopted for accurate steady-state output and rapid dynamic response performance.Finally,both the anti-disturbance ability and robustness of compressor system have been heightened by introducing a disturbance observer.In order to enhance the ability of flux-weakening expansion speed and extend the running range at high frequency,as well as improve the running stability of flux-weakening control on frequency conversion compressor,we have conducted an in-depth research on voltage utilization and stability influence factors when running at flux-weakening state in this thesis.Firstly,a flux-weakening control strategy based on an integrated SVPWM modulation mode has been studied,which is able to extend the region of linear modulation and optimize the over-modulation region.Moreover,the dc bus voltage is utilized fully and the voltage output range is enlarged.Therefore,the frequency conversion compressor can run at a higher speed.Then,on the basis of the above flux-weakening control strategy,the influence factors of stability when running at the high speed flux-weakening has been analyzed,and a high-performance flux-weakening control strategy has been proposed for resistance voltage drop loss and distortion voltage of inverter nonlinear.Meanwhile,in allusion to the issue of insufficient torque output capacity on the flux-weakening region,a flux-weakening control strategy on maximum torque control frame is researched combining the MTPA control method,the torque output capacity is improved.Finally,on the drive system platform of the frequency conversion compressor,many corresponding flux-weakening experiments are conducted.The experimental results verify the superiority of proposed flux-weakening control strategy.In order to improve the sensor-less control operation stability of frequency conversion compressor,we have analyzed the reason of compressor sensor-less control performance influence in this paper,then proposed a sliding mode observer based on Lq model,adaptive notch filter and quadrature phase locked loop technology.Firstly,we have studied a sliding mode observer based on Lq model,so as to reduce the impact of the d/q axe inductance difference on sliding mode observer accuracy.Secondly,by introducing the adaptive notchfilter,the problem of inaccurate rotor position observed value caused by higher harmonic component of back electromotive force has been solved,and the accurate tracking and phase locking has been achieved by employing the quadrature phase locked loop technology.Thirdly,an initiative smooth switching strategy has been investigated for settling the low switch successful rate when the compressor starting.Finally,many corresponding sensor-less control experiments has been conducted on the drive system platform of the frequency conversion compressor.The experimental results have demonstrated the effectiveness and superiority of the proposed compressor sensor-less control strategy,as well as achieved high performance with sensor-less control of compressor in whole frequency range.