一种适用于三电平逆变器的开关电源设计

A Kind of Switching Power Supply Applied to Three-level Inverter

介绍了一种适用于三电平逆变器的开关电源。该电源在启动时采用电网供电,在逆变器直流侧电压达到额定值时,从逆变器直流侧储能电容下电容上取电。由于开关电源直接从直流侧储能电容下电容上取电,因而,开关电源的最大输入电压仅为三电平逆变器直流侧额定电压的1/2,并且在逆变器主系统突然掉电后,开关电源仍能工作一段时间,这保证了掉电后保护动作依然能可靠执行,提高了逆变器主系统的安全性。同时,设计了储能电容放电回路,使得系统正常工作时,放电回路无损耗,当逆变器直流侧掉电后,给储能电容提供放电回路。开关电源主电路基于单端反激式变换原理,工作在电流断续模式(DCM)。实验结果证明,开关电源符合设计要求。目前,该开关电源已成功应用在一台三电平逆变器样机上。

A kind of switching power supply which is applied to three-level inverter is introduced.The electricity is adopted by the power supply from grid when it＇s starting.The electricity is gotten from the capacitor of the inverter DC side when the DC side voltage is researched at the rated value.The maximum input voltage is only 50% of the three-level inverter DC side rated voltage.After suddenly losing the power of the main system of inverter,switching power supply can still work for some time to guarantee that the protective action can still carry out reliably and to improve the safety of the main system of inverter.The return circuit of discharge capacitor is designed, and when the system works regularly, there is no loss in return cireuit.After losing the power of inverter DC side, switching power supply can provide energy-storage capacitor with capacity and release circuit.The main circuit of the switching power supply works on the discontinued current mode （DCM）, and the design has been applied to a three-level inverter and the experiment proves that the switching power supply can meet the requirement of the design.