The Manufacture Of260kW Medium-voltage Three-level Charge And Discharge Equipment

As a storage deviceof high energy density, fast charge and discharge, no memory effect, stable and reliable,lithium-ion battery pack is widely used in the field of electric vehicles.Recently, China’s first hybridEMUformally put into production.Lithium battery as a power source for hybrid EMU,the battery needs charge and discharge absolutely to enhance its performances. Meanwhile, due to small loss and low cost,high-voltage and low-current charge and discharge equipment has become a trend.At present, the output voltage of thelarge power charge and discharge equipment is generally not high, there is no suitable high voltage charge and discharge devicefor hybrid EMU.To increase the output voltage level and achieve two-way flow of energy from the grid to the battery pack, this paper has designed a260kW medium-voltage three-level charge and discharge equipment, which used a three-level NPC three-level PWM Rectifier and bi-directional DC-DC converter series two-stage three-leveltopology structure.The article focuses on the principles and parameters designing of the main circuit, and the resultshave been validatedwith the simulation and experiment.Firstly, the topology and principle of charge and discharge equipment have been discussed. The parameter design method of these two parts is introduced, including theDC-side capacitance, L filter, battery-side capacitance, inductance and some other key parameters.The control strategy of the equipmenthas also been introduced,VOC(voltage oriented control) of first stage and voltage or constant current control ofvoltage and current double closed-loops of the secoud stage.Secondly, the power loss of the two stage circuits has been discussedin detail, andthe engineering calculation and simulation ofthe power losshave been compared, the power module is designed based on heat loss distribution and temperature rise. With double pulse experiment and temperature experiment of the power module, the technical parameters hasidentified, and the practicability of modular power componentshasbeenverified.Finally, experiments of260kW high power converter are carried out, includingcharge experiments, THD and so on. The experimental waveforms and data show thecorrectnessoftheresearchresultsandthe feasibilityofthedesignscheme.