At present, virtual flux voltage oriented control strategy is one of the widely used control strategies without grid voltage sensor. To solve the dc bias resulting from voltage vector integration in vector calculation of virtual flux and further avoid the steady state error. This paper presented a virtual flux observer with negative feedback resonant filter based on virtual flux principle. And is also proposed a delay compensation algorithm to solve the delay of virtual flux. In addition, the paper has brought forth the control system diagram of P WM rectifier without grid voltage sensor . Then, simulation system platform simulates the rectifier. Eventually, the analysis of simulation results verified the correctness and feasibility of the proposed algorithm.
Fig.1 The diagram of control system of P WM rectifier without grid voltage sensor based on virtual Flux.
EXPECTED SIMULATION RESULTS:
Fig. 2 DC Side Voltage and AC Side Current.
Fig. 3 Harmonic Analysis of A Phase Current.
Fig. 4 The Output Angle of Phase-Locked Loop and that of Virtual Flux During Uncontrolled P WM Rectifier
Fig. 5 The Output Angle of Phase-Locked Loop and that of Virtual Flux During Controlled Rectifier.
Fig.6 The Output Angle of Phase-Locked Loop and that of Virtual Flux During Uncontrolled Rectifier after Compensation.
Fig.7 The Output Angle of Phase-Locked Loop and that of Virtual Flux During Controlled Rectifier after Compensation.
This paper analyzed the Mathematical model of virtual flux algorithm. And proposed the virtual flux observer with negative feedback resonant filter. The simulation results show that the proposed virtual flux observer can realize flux estimation without steady state error and it has better dynamic characteristics than series algorithm of dual low pass filter. Furthermore, adjusted the relevant parameters of the observer. Eventually, brought forward a delay compensation algorithm to solve the delay of virtual flux, which can effectively compensate the error caused by system delay to flux observation. In this paper, the aging of electric reactor is not taken into account. The estimated value of virtual flux is bounded to change with the change of inductance.
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