The Design Of Energy-get Power Supply For Intelligent Equipment In Distribution Network

At present, our country is promoting the planning and implementation of smart grid.With the continuous construction of smart grid, in order to ensure the line real-time detectionand control, the application of smart devices are more and more.The current intelligentdevices most use battery power supply to solve the problem of energy supply, but the life ofthe battery is limited, the power is not high and the replacement is inconvenient. Therefore, inorder to solve the limitations of battery power supply, this article puts forward the scheme ofgetting energy from the scene for the using of equipments. Considering the volatility of linecurrent, the device operates in three kinds of mode, taking different energy-getting ways inview of different currents. Use current transformer (CT) to get energy when the line current isbetween20-800A; when the line current is big and the induced voltage of main core is high,the device puts compensating coil into use to offset part of the energy; when the line current issmall, the device uses uses the method of coupling resonance to realize wireless energytransmitting, ensuring the normal supply.The most important part of the CT energy-get is the design of the core. First of all,according to the power requirements of the design, the article makes sure the parameters suchas core area, the magnetic gap size, inner and outer diameter size, the length of the magneticcircuit and the equivalent permeability through a series of theory analysis and calculating. Atthe same time, select the core material and the shape of the core. Second, set up differentcircuit module, including the front impact protection module, rectifier filter circuit, voltageconversion circuit. Finally, use the Saber software to simulate and when the primary sidecurrent is between20-800A, the main coil can obtain stable voltage and secondary voltage iswithin the normal range. In the end, the simulation results verify the validity of core materialand shape and the designed parameters and the feasibility of the scheme. In addition,considering the lightning or short circuit current value will be very big, in order to guaranteethe normal work and safety of the device, Zener diode is adopted to define compensating coilusing point. When the main coil induction voltage is greater than17.2V, Zener diode reversesbreakdown and the voltage remains the same. The compensating coil is put into work and itsmagnetic flux will offset part of the main magnetic flux, preventing excessive voltage to appearing.Considering that the CT energy-get part may not realize power supply when the linecurrent is small, the article puts forward the design of wireless energy-get circuit. This partdetects the main core voltage through voltage detection module and when the voltage is lessthan3.3V, the device uses wireless way to get energy. First PWM control chip and driver chipmake the half bridge inverter produce high frequency coupling resonance, realizing thewireless energy transmitting. Receiving coil part includes rectifier filter circuit and powerconversion circuit, and eventually the device gets the voltage for load power supply.The design fully considers the volatility of the line current and creatively uses differentways according to different current ranges to realize supply of energy in three modes. Theswitch of the device is simple and the whole circuit is clear. Finally, the designed powersupply guarantees the stability and reliability of energy supply when the line currentfluctuation is big.