Research On The Motor Control Of Four-Quadrant Converter

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.