Developing Of An Intelligent Digital Inverter Power Supply System

Studies on high-powered inverter power supply system are one of the focuses in power electronics field. This thesis developed an intelligent digital inverter power supply system. The key part of the system includes the controls of power inverter, synchronization control and manipulation of static switches, and monitoring of multi-modules through computer networks. The main circuit of the inverter contains an H bridge, drive circuit, protection and detection circuit, etc. Syncretizing the technologies of DSP and CAN bus, the system consist of two chips of DSP, one chip of 89C52, a CAN bus controller, and other peripheral equipments. One DSP as the master control chip of power inverter module is in charge of DC-AC controls. Intelligent PI control strategy and Single Polarity Double Frequency SPWM are adopted to insure the stability of the output voltage. The other DSP as the master control chip of switch apparatus/static switch, function in synchronization and switch controls of double power supplies. Via CAN bus isolation circuit, DSP is connected and communicate to the slave which adopted 89C52 as the master controller. 89C52 along with the CAN controller and interface chips of the monitoring and control complete the task of communication and monitoring of system. When it comes to the communication to the master, RS-232 or MODEM and telephone lines are used to achieve the local or remote operations. Multiple CPU structure based on DSP and CAN described above is a hardware foundation for realization of high-precision and high-performance intelligent control system.The inverter was designed strictly conform to the national standard YD/T777-1999 P.R.C. All parameters of the inverter measure up well. The inverter can synchronously track the network power precisely with the help of the static switch, and the switch operation is done in less than 2.4ms bidirectionally, an instant short enough as to be viewed as "seamless".This thesis also made some researches in three-phase four-leg inverter. It introduced a new topology of the main power circuit as well as a new method to control the inverter, which can output 220V voltage with a transformer which is suitable for civil electrical equipments, the decoupling of three phases makes each phase work separately, and there is no precedent literature addressing this issue. The simulation results proved it adapts to balanced and unbalanced loads, which will theoretically guide the further study.