Space Vector Modulation Technology Research Articles

Bidirectional PWM Converter to Interface AC Part to DC Microgrid with Neutral Potential Balancing

This research presents a description of a bidirectional pulse width modulated converter that functions as a rectifier by using the direct power control strategy and space vector modulation technology. In contrast to the voltage-oriented control strategy, this method minimises the number of internal current loops and requires more tuning. While functioning as an inverter, it applies the space vector modulation technique as well. The approach, on the other hand, is not the same as rectifiers since it calculates the duty ratio of the neighbouring voltage vectors in each small triangle that is generated in each sector that has a period of 60 degrees. In both situations, the neutral point potential has been brought back into equilibrium.

Model-Free Predictive Current Control of Five-Phase PMSM Drives

Model predictive control is highly dependent on accurate models and the parameters of electric motor drives. Multiphase permanent magnet synchronous motors (PMSMs) contain nonlinear parameters and mutual cross-coupling dynamics, resulting in challenges in modeling and parameter acquisition. To lessen the parameter dependence of current predictions, a model-free predictive current control (MFPCC) strategy based on an ultra-local model and motor outputs is proposed for five-phase PMSM drives. The ultra-local model is constructed according to the differential equation of current. The inherent relation between the parameters in the predictive current model and the ultra-local model is analyzed in detail. The unknowns of the ultra-local model are estimated using the motor current and voltage at different time instants without requiring motor parameters or observers. Moreover, space vector modulation technology is employed to minimize the voltage tracking error. Finally, simulations and experiments are conducted to verify the effectiveness of the MFPCC with space vector modulation. The results confirm that the proposed method can effectively eliminate the impact of motor parameters and improve steady-state performance. Moreover, this control strategy demonstrates good robustness against load variations.

Research on Pressure Control of an Electro-Hydraulic Servo System Based on Sliding-Mode Variable-Structure Direct Torque Control

Taking a direct-drive volume control (DDVC) electro-hydraulic servo system as the research object and aiming at the problems of the servo motor torque fluctuation, high-precision system pressure control, and dynamic response of the system, based on traditional motor direct torque control (DTC), a motor direct torque control method based on a sliding-mode variable structure is proposed to control the system pressure. The motor torque loop is part of the inner control loop and has a rapid dynamic response speed, resulting in higher pressure control accuracy. A nonlinear mathematical model was established for the DDVC electro-hydraulic servo system. The switch meter hysteresis controller in the traditional DTC system was replaced with space vector pulse-width modulation technology. Then, the PID control module in space vector modulation technology was replaced with high-order sliding-mode variable-structure control. Through the coupling relationship between the electric machine and the constant-displacement pump, the pressure can be controlled with high precision using motor torque control. Finally, using the MATLAB/Simulink simulation platform and the DDVC electro-hydraulic servo system simulation model, the proposed theoretical approach to torque control was verified on the basis of simulations and experiments, and the performance with regard to pressure control in the hydraulic system was observed. The simulation and experimental results show that the designed torque control is able to effectively reduce the motor torque fluctuation and improve the dynamic response characteristics of the system. The system pressure control is superior to traditional pressure control methods based on speed regulation, and it has higher control accuracy and a better dynamic response.

Examination and implementation for direct torque controlled permanent magnet synchronous motor with space vector modulation

This study investigates the direct torque control strategy of permanent magnet synchronous motor with the space vector modulation, on account of large torque fluctuation and varied switching frequency of classic direct torque control strategy. The relationship among the terminal control voltages and the torque and stator flux of the permanent magnet synchronous motor is derived through the dynamic model of motor. Accordingly, the torque and the flux closed-loop feedback control structure are established, where the error signals are regulated by the proportional and integral controllers to generate output voltages. Furthermore, the parameters of the controllers are designed through explicitly analyzing the frequency domain models of the torque control loop and the flux control loop. The accurate calculation formula of control parameters, which has both explicit setting target and definite physical meaning, is obtained. Therefore, the design of torque and flux controller parameters becomes easy in the direct torque control with space vector modulation technology, and satisfactory flux and torque control can be acquired. Finally, simulation and experimental tests are demonstrated in support of the validity of the investigated scheme and the feasibility of the proposed controller parameter design.

Fuzzy direct torque control for induction motor drive system based on space vector modulation

A new approach of a fuzzy direct torque control and drive (FDTC) for induction motor drive system based on space vector modulation (SVM) technology is proposed in this paper. By comparing the conventional direct torque control using space vector modulation technology (SVMDTC) method with the fuzzy direct torque control, a fuzzy controller is used to replace the PI conventional speed regulator. In the proposed strategy, the error between the estimated and the referred linkage flux of the stator and torque will be compensated by an accurate synthesised space vector voltage. Simulation results show that the proposed SVM-DFTC method can improve the system robustness, evidently reduces flux and torque ripples, and in turn obtain a swift speed response with extraordinarily high improvement of its performance.

Research on Cascade Multilevel Inverter Control Strategy

Due to easy realization and high equivalent carrier frequency, the Carrier Phase-Shifted pulse width modulation technology has been applied in the multilevel modulation circuit. Space vector modulation technology has a wide range application because it is easy to realize and has the advantage of high DC voltage utilization. However, when it is directly used in a cascade inverter system, it becomes difficult to be realized because of the too many synthesis voltage vectors and switch states. This paper puts forward a new control strategy based on the technology of carrier phase-shift and vector control by means of combing the advantages of Carrier Phase-Shifted with the SVPWM. The simulation results show that the control strategy is feasible. It is not only has good harmonic characteristic and high equivalent carrier frequency, but also has advantages of high DC voltage utilization and easy digitization.