Design And Research On The Energy-feedback Electronic Load Control System And Load Model Database

In recent years, with the rapid development of power electronic technology, the powerelectronic devices are used widely.They include the LED driver power supply,uninterruptible power supply (UPS), AC, DC power supply, variable frequency powersupply and so on. Electric vehicle, mobile phone and photovoltaic off-grid inverter areused widely, because they all require energy storage components, so the battery aredeveloped rapidly, such as the lead acid battery, the lithium battery, the nickel-cadmiumbattery and others. Before the products put into use, they need to be examined with variousloads to assess their accuracy, stability and lifetime performance. The traditional testmethods generally use the resistance, inductance, and capacitance load. The value and typeof the loads are hard to modify, and are used inconveniently; values of the loads arechanged with the change of the temperature, so the accuracy is not high; when tested theenergy was dissipated in the form of the heat, so they waste energy seriously, and not besuitable for high power applications. Basing on the improvement of test automation andenergy saving requirements, it need a new kind power electronic load test deviceThe design of the overall system is for the23kW electronic load. According to thetarget selection of design, I choose the topology of common DC bus in the double PWMstructure as the main circuit topology. The former is a single-phase rectifier, and the latteris a three-phase active inverter. At the same time the electronic load control strategies aredefined.The hysteresis comparison tracking control strategy is used in the side of PWMrectifier, while the PWM triangular carrier modulation method is used in the side of PWMinverter.The double loop control strategy uses the voltage loop in outer and use the currentloop in interior. First the main circuit and control strategies are determined, and thendesign the overall system, introducing the working principle and the boot order. Finally thearticle gives an introduction of the selection principle to make sure the main circuitparameters of electronic load.There are many types loads. It is wise to research and establish the load modeldatabase. Classify loads and modeling to get the mathematical model; then generatedifferent load model of rectifier side to track instruction recursion formula. Design theLabVIEW interface on the computer, use LabSQL to access Microsoft Access database andload types and parameters and other information using serial communication mode to lectronic load.The load model database and electronic load are linked up effectively,finishing the parameter configuration of intelligent electronic load.The main circuit is taken by the common DC bus dual PWM converter structure. Therectifier and the simulation side can be separated from the control. PWM rectifier simulatesloads, storing power energy in the DC bus capacitor while three-phase PWM inverterlinked with power grid by the unit power factor, feeding the stored energy of DC bus intothe grid. Making the study of the relationship between the bus bar voltage ripple and thetwo stage converter in depth, double closed loop regulator is designed for P regulation. Atthe same time, use differential conditioning to reduce the influence that the bus voltageripple on the inverter side make on the current instruction and give the detailed designprocess of the regulator.In the end, some results are given. The results show that the electronic load circuitworks normally; load model database and man-machine interface make loading parametersetting conveniently.