【作者】 王恩德；

【导师】 黄声华；

【作者基本信息】 华中科技大学 ， 电气工程， 2013， 博士

【摘要】 采用三相PWM整流替代传统变频器中的不控整流而构成的四象限变频器,同时具备了交流电机优异的调速性能和三相PWM整流的能量可双向流动、网侧电流正弦度好、单位功率因数、直流母线电压可控等优点,非常符合国家重点实施的节能减排战略。本文以四象限变频器为核心,围绕PWM调制、PWM整流、异步电机控制、永磁同步电机控制、四象限变频器协调控制等关键技术、以及四象限变频器扩展应用,进行了理论分析和研究。PWM技术是PWM整流和交流调速的基础。本文详细分析了SPWM和SVPWM两种调制方式,阐述了一种实现简单的SVPWM调制方式；结合工程实现,采用了一种可提高了直流母线电压利用率的过调制方式,并成功实现了一种可有效减少开关次数提高系统效率的DPWM方式；重点分析了死区的形成原因和其对控制系统的影响,并阐述了基于两相同步旋转d-q坐标系下的死区补偿方式和实现特点,并给出了这种死区补偿方式的仿真和实验结果,为四象限变频的控制打下了基础。电流环作为电压、电流双闭环控制的内环,直接决定着三相PWM整流的电流波形好坏,影响其性能。传统电流解耦控制方法需要知道准确的电感参数,而工程实际中电感参数的测量并不方便,并且电感在流经大电流时容易饱和,导致解耦控制失败；三相PWM整流的电压外环存在非线性,若直接采用传统的PI控制器,难以取得比较好的动态特性。本文提出了一种无需知道电感参数的电流解耦内环电压平方外环的电压、电流双闭环控制策略,仿真和实验结果验证了该控制策略的可行性。V/F控制和矢量控制是异步电机两种非常重要的控制方式,本文分析了异步电机稳态模型,针对V/F控制下异步电机空载或轻载时容易振荡的现象,采取了基于无功电流闭环的控制方案,实验结果验证了该控制策略的可行性。同时本文给出了异步电机的动态模型,并进一步分析了异步电机转子磁场定向矢量控制,实验结果验证了基于转子磁场定向矢量控制的异步电机具有非常理想的动、静态特性。异步电机参数辨识有离线辨识和在线辨识两种方式,本文重点分析了异步电机参数的离线辨识,提出了一种简化的无需进行傅里叶变换提取正弦信号的幅值和相角的方法,实验结果证实了该方法的可行性。异步电机参数辨识为异步电机无位置传感器矢量控制提供了基础,仿真和实验结果验证了本文所提出的自适应无位置传感器矢量控制策略的可行性。通过更换编码器接口和控制算法,变频器同时也能够实现同步电机的驱动。针对永磁同步电机电流环,本文提出了无电感参数解耦和比例谐振控制器方案,减小电流谐波。仿真和实验均验证了该方案的可行性。四象限变频器逆变部分可等效成一个电阻+电感+反电势的等效电路,所以理论上讲四象限变频器的三相PWM整流和逆变部分可以独立控制,即三相PWM整流控制直流母线电压,逆变器控制电机特性。本文搭建了四象限变频器实验平台,实验结果实现了四象限变频器的基本工况。为了提高四象限变频的抗负载扰动能力,本文提出了一种在不增加直流母线电流采样的前提下,基于负载电流观测器的负载电流前馈补偿的控制策略,并分别采用了降维观测器、基于简化模型的扩展卡尔曼滤波(Extended Kalman Filter, EKF)和基于完整模型的EKF三种观测器,实验结果验证了该方案的可行性。拥有两个电端口的新型电机是四象限变频器的重要应用对象。本文以四象限变频器应用于无刷双馈发电机为例,描述了其应用特点,并针对防止电流冲击和改善抗负载扰动能力,提出了解决方案。实验结果验证了该方案的可行性。更多还原

【Abstract】 Four-quadrant inverter with the boost rectifier instead of the conventional non-controlled one, is very much in line with the national focus on the implementation of energy conservation strategy, because of the advantage shown as excellent performance of the AC motor, double direction energy flow, the grid’s current sinusoidal, unity power factor, and the controlled DC bus voltage. There are a large number of papers based on the boost rectifier and AC variable speed control, which provide a basis for the research on the four-quadrant inverter. This paper does some research on the theory and control strategies of the rectifier, the control of the induction motor, the control of the permanent magnet synchronous motor, the four-quadrant control and its extended application.PWM is the basis of the boost rectifier and AC variable speed control. The detailed analysis of SPWM and SVPWM, and a simple SVPWM method are introduced. An overmodulation method and a DPWM method, which can improve the system’s efficiency, are also described. The reason for the deadtime is also analysised, and a deadtime compensation strategy is introduced. The simulation and experimental results are given.The performances of the boost rectifier and currents are directly determined by the inner loop (the current loop).Conventional current decoupling control method, which is very inconvenient in engineering, needs to know the exact inductance parameters. It is difficult to obtain a well dynamic performance with the tradional PI controller, because of the changed conduction caused by saturation. A novel control strategy, which contains a current decoupling inner loop without the inductance parameter and a voltage square outer loop, is proposed in this paper. Simulaton and experimental results verifies the feasibility.The induction motor is a stong coupling model. And the V/F control and vector control are two very important methods for the control of the induction motor. The steady-state model of the induction motor is analysised and a control strategy with the reactive current closed-loop control is used. The feasibility is verified by the experimental results. The dynamic models in several different coodinates are also presented. The rotor field oriented vector control of induction motor is achieved to satisfactory the dynamic and static characteristics with the experment results. Off-line and on-line parameters identifications are two mainstream methods for identification of induction motor’s parameters. This paper focuses on the off-line identification, and a simplified method without the Fourier transform to extract the sinusoidal signal amplitude and phase angle is proposed. The feasibility is verified by the experimental results. The feasibility of the adaptive sensorless contol strategy, with the identified parameters and the proposed method, is verfied by the experimental results.Induction motor and synchronous motor can both be driven by the inverter with the encoder and control algorithm changed. A current decoupling control and proportion resonant controller is proposed to reduce the current harmonics. The feasibility of the proposed method is verified by the simulation and experimental results.The four-quadrant inverter’s inverter part can be equivalent to a resisitor+inductance+back EMF, so the boost rectifier and inverter can be independently controlled, with the rectifier contolling the DC bus voltage and the inverter controlling the motor. The four-quadrant expermental platform is built to realize the four-quadrant condition. In order to improve the anti-load disturbances of the four-quadrant, the load current based on the observer feed-forward compensation control strategy is proposed, which concluding reduced order observer, extended kalman filter (EKF) based on the simplified model, and EKF based on the complete model. The feasibility of this strategy is verified by the simulation and experimental results.The four quadrant inverter is also suitable to be applied to the new motors with two power ports. The brushless doubly fed generator is taken as an example to describe the applications. And a strategy, preventing the current impact and improving tha load disturbances, is also proposed. The feasibility of this strategy is verified by the experimental results.更多还原