Design And Research On On-board Type Medium-Voltage Four-Quadrant VTF For Coal Mines

With the development of variable frequency technology,variable frequency drive(hereafter shorted as VFD)is widely used in undergrounding coal mines.Especially,to solve the serious waste of power energy at coal mines,the four-quadrant VFD has been applied to realize two-way flow of energy,feeding energy back to the grid,greatly improving power saving rate and reducing overall production costs.On-board type VFD is able to be installed on longwall machines such as shearers,roadheaders,AFC's(armored face conveyor)due to its small size and easy-to-go maintenance feature.However,at present,the domestic technology of medium-voltage VFD for coal mine use is still under development.The research on on-board type medium-voltage four-quadrant VFD for mine use is of great significance.Focus on the on-board type medium-voltage four-quadrant VFD for mine use,firstly,studies of the four-quadrant VFD and forms the PWM three-phase rectification mathematical model.Based on the analysis of SPWM and SVPWM modulation principle,its algorithm formula is derived.In addition,it analyzes the control strategy of four-quadrant VFD mainly including PWM three-phase rectification control and motor vector control.The stability of the system and the feasibility of the algorithm are verified through simulation analysis.Secondly,the paper illustrates the design of the four-quadrant VFD hardware part including various electrical connections and the PCB's,as well as the corresponding testing to verify the reliability of the hardware.Software system of the four-quadrant VFD is also provided to perform the main functions on the basis of hardware design.Finally,the paper shows the tests are done to verify the complete on-board type medium-voltage four-quadrant VFD as designed.Running with no-load and basic functions one by one are carried out respectively.Loading test is also done later.The experimental results show that the designed VFD can well meet the requirements.