Research On Energy Feedback Device In Oil Pumping Unit

The pumping unit motor driven by frequency converter is in the state of power generation in part of time. The result is increasement of the inverter DC bus voltage. The traditional solution is to add resistance on both sides of DC bus. This method makes the resistance heat, temperature of the converter cabinet rise. It is harmful to operation of invertor reliably and the energy is wasted. Therefore, a device is designed in this paper. It can send the power generated by pumping unit to the power grid to save energy and improve effenciency. The main work and the results obtained are as follows:1. In order to meet the requirements of invertor controller, the principle of SPWM and SVPWM mathods is analyzed deeply. Simulation and tests are completed. The results show that SVPWM has higher utilization rate of DC voltage and lower harmonic than SPWM. But the algorithm is more complex and harder to program than SPWM.2. Based on utilization of SVPWM control method, the principle of voltage loop, current loop and voltage and current double closed-loop control is discussed. The control method is proved reasonable by simulation.3. The hardware design of main circuit, filter, signal conditioning circuit, driver etc. in pumping energy feedback device is introduced in detail. The validity is verified by experimentation.4. The implementation of SVPWM algorithm in MCU TMS320F2812, source code and test waveforms are presented. Using MCU TMS320F2812 for SVPWM is superior.