【作者】 张晓东；

【导师】 王兵树；

【作者基本信息】 华北电力大学（北京） ， 控制理论与控制工程， 2010， 博士

【摘要】 随着电力电子技术和计算机控制技术的发展,串级调速技术重新受到人们的关注,近年来发展起来的内反馈斩波串级调速技术以其调速性能好、控制精度高等特点受到人们的亲睐,尤其是在高压大容量电动机调速方面,展现出良好的节能前景。目前,内反馈斩波串级调速技术普遍采用可控硅晶闸管逆变器进行电能的反馈,虽然采用斩波控制技术较大地提高了系统功率因数,但依然存在晶闸管换流引起网侧电流波形畸变、低速时功率因数降低及逆变颠覆等的不足。针对以上不足,文中提出采用三相电压型PWM逆变器代替传统晶闸管相控逆变器,利用三相电压型PWM逆变器功率因数和直流侧电压可控的优点,从结构上打破了传统可控硅串级调速技术因电路结构限制而不能进一步提高系统功率因数的局限性。本论文首先从研究基于晶闸管逆变器的内反馈斩波串级调速技术入手,分析了内反馈调速电动机电磁关系,为建立内反馈电动机仿真模型提供理论依据；通过对内反馈斩波串级调速系统直流回路的分析,揭示了斩波串级调速系统的工作原理及其节能原理,并对内反馈斩波串级调速系统的谐波和功率因数进行分析,给出提高系统功率因数和减小系统谐波“污染”的可行方案,即采用三相PWM逆变技术,在保持原有斩波串级调速技术优点的基础上,结合三相电压型PWM逆变器的控制特点,通过提高逆变器功率因数来提高整个系统的总功率因数,并通过控制逆变器交流侧电流的波形,减小系统谐波“污染”。由于目前PWM逆变器在串级调速系统中的应用较少,甚至仍停留在理论研究阶段,因此本文建立了基于三相电压型PWM逆变器的内反馈串级调速系统的仿真模型,通过仿真实验,进一步验证了PWM逆变器在串级调速系统中应用的可行性,这为PWM逆变器在工程上的应用研究提供了便利；文中还针对串级调速系统功率因数随转速下降而降低的不足提出了可行的解决方案,即通过控制PWM逆变器的无功电流,使逆变器产生容性无功功率,补偿因转子整流而产生的感性无功,使系统在低速时也能保持较高的功率因数。通过仿真研究,系统地分析了基于三相电压型PWM逆变器的内反馈串级调速系统的特性以及在运行中可能出现的问题,这为三相电压型PWM逆变器在工程上应用提供了较为可靠的理论依据。更多还原

【Abstract】 With the development of power electronics technology and computer control technology, the cascade speed regulation slip power recovery technology of 3 phase motor renewed attention, in recent years, chopper circuit used in cascade speed regulation technology of inner-feedback motor with its good performance and high precision control shows good prospects for energy conservation in the high voltage & large power motor.At present, the chopper cascade speed regulation technology of inner-feedback motor adopts commonly SCR thyristor inverter to feedback the slip power of the motor to grid, although the use of chopper control technology has greatly improved the power factor, there are still many disadvantages:the voltage waveform of grid is distort, the power factor is reduced in lower speed and the inverter subversion can be happened some cases because the use of thyristor inverter.For lack of above, in this paper, using three-phase voltage-type PWM inverter instead of the traditional thyristor inverter, with it’t advantages:Three-phase voltage-type PWM inverter power factor and the Controlled DC current, from the structure, it breaks the limitations of traditional SCR cascade control technology can not be further enhanced the system power factor as the circuit limitin this paper, the cascade speed control technology of inner-feedback motor based on thyristor inverter has been researched, and the electromagnetic relations within the inner-feedback motor has been analysed, which provide a theoretical basis for the establishment of simulation models of the inner-feedback motor; By analyzing the direct current loop of the chopping cascade control system of the inner-feedback motor, the principle of the chopping cascade control system has been revealed. The power factor and the system harmonics have been analyzed, and the way of improving power factor and reducing harmonics has been given. The three-phase PWM inverter technology has been used in the cascade control system, and the new system maintain all the merits of the original chopping cascade control system, and combinating the characteristics of the three-phase PWM inverter, the power factor of the cascade speed control system will be improved by increasing the inverter power factor, and the harmonics pollution will be reduced by controlling the inverter AC side current waveforms.As there are less the PWM inverter applied in the cascade control system, and it even still at the stage of theoretical research. So, in this paper the simulation model of the cascade speed control system of inner-feedback motor based on the three-phase voltage-type PWM inverter is rebuild and it has been proved accurate by the theoretical analysis and simulation results, which provide the convenients for the PWM inverter applications in engineering; because the power factor of the cascade speed control system decreases with the speed dropped, the feasible solution had been designed by controlling the PWM inverter reactive current to produce capacitive reactive current compensation for speed device by inductive power, so the system can maintain high power factor in a low speed. The characterisics and the potential proplems in peration has analyzed by the simulation experiments systematically, which provide a more reliable theorical basis for the engineering application.更多还原