The Study And Design Of High-Frequency Switching Power Supply For Cathodic Protection

With the continuous development of our economy, increasing demand for energy, oil, transport, storage capacity increases, pipeline, tanker, tank corrosion protection has received increasing attention. Cathodic protection is widely used to slow or prevent corrsion of the steel materials underground and buried pipeline. As a rectifier for cathodic protection, the conventional phase-controlled rectifier with 50-or 60-Hz isolation transforms have been used so far in spite of such shortcomings as large volume, heavy weight, and poor power factor. In order to overcome such disadvantages, this article applies high-power switching power supply technology to the field of cathodic protection, and develops a high frequency switching power supply cathodic protection.Firstly, this thesis discusses the high-power switching power supply soft switch technology, for the full bridge phase-shifted zero-voltage converter (FB-ZVS-PWM converter) some disadvantages, such as the duty cycle loss, and loss of the larger situation. The main circuit uses Phase-Shifted Full Bridge Zero-Voltage Zero-Current Switching PWM Converter (FB-ZVZCS-PWM converter), to achieve soft switching of power control, ultra-forearm to achieve zero voltage switching, zero-current switching delay arm, and its basic working principle has been described at the same time. This paper also gives some strategies to achieve ZCS lagging arm.Secondly, this thesis designs the hardware of the FB-ZVZCS-PWM converter in detail, including the design of the high-frequency transformer, inductances, capacitors, control circuit, drive circuit of IGBT and A/D. It also designs the software. In order to obtain accurate and real-time control, high performance digital signal controller dsPIC30F2020 is adopted for control core. And the voltage feedback PI algorithm is used to adjust the output voltage and current character of power source.Finally, this thesis builds the experimental platform of energy storage system according to the design requirements.Experimental results show:high power DC-DC converter is suit for cathodic protection. This paper also shows that the control system has many advantages such as high control precision, man-machine conversation and reliable performance.