The operating principle of three-level Neutral-Point-Clamped(NPC) Voltage Source Rectifier(VSR) is analyzed. Then a high performance control method with d-q axis decoupling and neutral point voltage control for the PWM rectifier is presented.
This text summarizes the protective zero terminating system of the electric equipments. While the load of the TN-C system is dissymmetry, by analyzing the neutral point voltage and comparing the neutral line current with the phase line current, this paper discusses the problems exist in the system and the corresponding replying measures. Finally, it analyzes several problems that should be noticed in the TN system.
Finally, a SVPWM control strategy, which can balance the neutral point voltage by changing the control factor on the basis of judging the DC Voltage of two capacitors and the directions of three phase output current, is presented.
Two kinds of methods of the zero-crossing of back-EMF sensing are analyzed,and the mothod of direct back-EMF is adopted to design the zero-crossing of back-EMF sensing circuit in which the motor neutral point voltage information isn’t needed.
Based on the theory that neutral point deviates when single phase-to-ground and double phase-to-ground insulation faults occur in floating ground power system,the relations between the faulty phase and the amplitude and phase of neutral point voltage to ground(UNN')are established. A method to locate insulation fault phase using the phase angle and amplitude of UNN'is propo-sed. An insulation fault phase locator based on MCS-51is designed.
In this case an easy way to balance neutral point voltage can also be achieved.
Finally, Figures 12 and 13 show the simulation result of the neutral point voltage control strategy.
This paper used analytical formulare,vector diagram,variable curues reflected variable law of three phases VS earth voltge,and neutral point voltage with single phase earthed resistor when single phase ground.Offered a new critical method of the grounded phaccd and are presented its aplication of the network operation
Working principle of the 3 level inverter as well as the principle and method to suppress deviation of its neutral point voltage are described. Simulation is done for the variable frequency speed control system of asynchronous motor. The simulation waveform is also presented.
In this paper,the basic principle of 3_level voltage source inverter is described.The voltage space vector control method is analyzed.The experimental results are presented.The method for restraining the deviation of neutral point voltage is expatiated.And the simulation waveform is presented.