| With the development of electric power electronic technology and large powerelectronic devices, a new type of power transformer named solid state transformer(SST) gradually emerges in recent years. Traditional power transformer’s function isto transform voltage, isolation and transfer energy. SST can not only realize thebasic functions of traditional power transformer, but also has the advantages of smallvolume, light weight, and no environmental pollution compared with the traditionalpower transformer. Besides, SST can ensure the original current, secondary voltagesinusoidal, and the control of the power factor is flexible. Power system is anonlinear system, but the optimal solution of the nonlinear system under the optimalcontrol is very difficult to get. However, if the tiny impact conditions of the systemcan be neglected, we can get the approximate linear system. Linear optimal controltheory has a very mature system, and the application is convenient. The optimaltracking control method can achieve the ideal output tracking, and the control iseffect. So this text chooses it as the control algorithm of the SST.First, this paper introduces the development, application and prospect of SST. Itintroduces the relevant theory of optimal control which mainly analysis the theory ofoptimal tracking control. Then it gets the principle diagram of the optimal trackingcontrol. In order to achieve the conversion of electrical energy in high voltage powersystem through low power device, SST chooses a topological structure, which iscomposed with series of multistage and same power module, and operating as amode of series. It sets up the mathematical model of SST and converted to DQ modeland designs SST control system according to the design steps of tracking controlsystem. According to the theories of SST and optimal tracking control system, itbuilds the SST simulation model which is based on Matlab/Simulink. Finally, thispaper design hardware circuit which is based on the DSP TMS320C28343. It alsointroduces the corresponding software flow. All of these laid the foundation for theproduction of SST experimental prototype.The simulation results show that SST optimal tracking control system canachieve the ideal output tracking. The error is small and it has a good control effect.It can realize the functions of ensure input current sinusoidal and the output voltage constant. And the concrete implementation of hardware also needs further researchand design which is the work required to complete. |
