| HVDC circuit breaker(HVDC breaker, High voltage direct current breaker) is a power protection circuit which can break a high voltage direct current circuit in case of overload or short, and the circuit will be reset when the fault is eliminated in the circuit. HVDC breaker is mostly used in the high voltage DC transmission system and distribution system to guarantee the safety and reliability of the system operation. Recently, on one hand, with the exploitation of the renewable energy, DC transmission technology is used more and more in the energy transmission process; on the other hand, with the rapid development of high technology, the requirement on high power quality by individuals and enterprises is continuously increased, and DC distribution is an important way and an improvement direction to improve the power quality in the distribution process. As the key component to keep the DC transmission and DC distribution operate safely and stably, the DC breaker has been paid more on attention and become a hotspot in the field of power electronics.With the continuous progress of se miconductor technology, Si C power device is becoming mature. Si C power MOSFET has many advantages over the traditional power device, such as high break-down voltage,high temperature, high switching speed, low conducting impedance and so on. The application of the Si C power MOSFET is promoted widely by these advantages. At the same time, contrast to the Si IGBT, the switching speed of Si C power MOSFET is faster and the effect of temperature changes is smaller. Through the analysis, we know that the Si C power MOSFET is suitable for the requirement of all-solid-state HVDC breaker on the power electronic switch.In this paper the all-solid-state HVDC breaker is designed and fabricated based on the Si C power MOSFET electronic switch. Firstly the application back ground and current situation of the HVDC breaker is introduced in this paper; then the circuit principle of DC breaker, the advantages and the circuit characteristics of Si C power MOSFET are mainly analyzed; through the analysis of the DC breaker circuit function, the circuit is divided into four functional circuit modules. A load circuit is used to simulate short-circuit fault, and the functional circuit is used to generate a corresponding control signal based on the changes in load current to break or reset the DC breaker. In the four modules, the current detection circuit modules are designed to detect the current change in the load circuit, the level latch circuit is designed to lock the generated control signal, the gate drive circuit is designed to achieve the boost and virtual ground of the gate-source voltage, and the reset detection circuit is designed to avoid false open operation. The all- solid-state HVDC breaker circuit with the Si C power MOSFET drive circuit is designed out based on the four functional circuit modules. According to the designed circuit, the DC breaker prototype is fabricated.The HVDC breaker is designed with the Or CAD simulation software in this paper, and the simulation results show that HVDC breaker circuit realized the break and reset function with the 12 KW load circuit, the stand-by power of the gate drive circuit is zero, and the circuit realized the locking of control signal, the boost and virtual ground of the gate-source voltage and the eliminating of error opening operat ion; At the same time, the HVDC breaker prototype is measured and the measurement results show that the power protection of the load circuit is achieved by the DC breaker, and t he function and the simulation results are consistent with about 30μs reaction time in the prototype.In this paper, the scope of application of the DC breaker is limited, and it is mainly used for purely resistive load circuit. The soft switch technology can be used to eliminate the overcurrent generated in the capacitive load or o vervoltage generated in the inductive load to expand its scope of application to all load circuit. |
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