Research On Variable Frequency Control Of Dual-PWM Converter Based On Single DSP

Variable frequency control of AC motor has been widely used in industrial control field, however, traditional frequency converter using uncontrollable diode to rectify causing current’s harmonic pollution, low power factor, no-energy feedback. Dual PWM inverter system using controllable rectifier to take place of uncontrollable rectifier, which can realize controllable input power factor, adjustable DC bus voltage, bidirectional energy flow and so on. Since it has so many advantages, it has been a hot topic in academia.Three phases PWM rectifier is a core part of the dual-PWM converter. This thesis first deduced power mathematical model of three phase rectifier, on this basis analyzed and designed a direct power control system of three-phase rectifier based on space vector modulation. As to its regulator parameters, tuned them in accordance with the best typical engineering system, and then used simulation to analyze and verify the control system as well as its regulator parameters.High-performance of motor control is a main purpose of the dual-PWM converter, this thesis use rotor field oriented control method which has excellent static and dynamic performance. As to the problem that its performance is greatly impacted by the rotor time constant, proposed an online method to identify the rotor time constant based on reactive power model, analyzed its discrete digital control realizing error, then used simulation to analyze and verify. In order to expand the controllable speed range of motor, a method which can maximize magnetic torque in field weakening region is proposed. By using simulation analysis and comparison, verified the proposed method superior to traditional method.Bus voltage stability has a great impact on the system performance, in order to stabilize the bus voltage, feed-forward control strategy using active power is adopted, then analyzed the anti-interference capability when using different feed-forward strategies and verified by simulation experiments.Finally, inductance parameter on the network side and capacitor parameter on the DC side of the dual-PWM converter is designed. Also, an experimental platform of the dual-PWM converter is presented using TMS320F28335 as core control microchip with the design of hardware and software, then conducted some experiments.