一种基于磁通控制的电磁感应式磁场能量收集器功率提升方法

As the “nerve endings” of the power grid, wireless sensor networks play a more and more important role in the construction of smart grid. How to provide energy for sensor networks stably and reliably has attracted people's attention, and magnetic field energy harvesting technology has become the most promising technology to solve this problem. However, the increase in the magnetic field strength around the power line will cause the magnetic flux density of the magnetic core to reach the maximum value, and the deep saturation of the magnetic core will cause power loss and threaten the safety of the harvester. In order to solve this problem, a power enhancement method of electromagnetic induction magnetic field energy harvester based on flux control is proposed in this paper. By adding controllable capacitor components in the circuit, the core saturation is alleviated and the energy collection power is significantly improved. The proposed magnetic field energy harvesting circuit adds a capacitor module which can change the series-parallel state between the load and the magnetic core coil, and its energy transmission process is as follows. At the beginning of each energy transfer cycle, the capacitor components are in parallel. Then, at the appropriate starting time of series, the capacitor module is controlled to be in series state, the voltage on the capacitor module is doubled, the voltage on the capacitor module is greater than the load voltage, the core voltage is reversed, and the accumulated flux is consumed. Core saturation is alleviated. Next, the control capacitor module returns to the state of parallel connection, and at the same time, the rising rate of core voltage is reduced by the larger capacitance in parallel, and the transmission time is prolonged. Simulation and experimental results show that the series start time t₁, capacitance value C₀ of capacitor module, load voltage V_load and primary current I₁ all affect the effectiveness of the proposed method. Among them, the influence of t₁ on the effect of the method is related to the voltage of the corresponding capacitor module, and the appropriate voltage of the capacitor module can give full play to the role of core reverse voltage in alleviating core saturation. C₀ affects the voltage change rate of capacitor components. The large change rate will lead to the rapid saturation of the magnetic core, while the small change rate will limit the effect of this method to alleviate the magnetic core saturation. After the load voltage is enough to make the core saturated, the larger the V_load and the deeper the saturation, the better the effect of the method. When the load voltage is not enough to make the magnetic core saturated, the average output current is increased by promoting the magnetic core saturation, and then the energy harvesting power is increased. With the increase of I₁, the change rate of capacitor module voltage increases, the reverse time of core voltage shortens, and the ability to alleviate core saturation decreases, which finally leads to the decrease of lifting efficiency. At this time, increasing C₀ and reducing the voltage change rate of capacitor components will help to alleviate the core saturation and improve the efficiency of energy harvesting. The following conclusions can be drawn from the simulation and experimental analysis: ①The proposed method can alleviate the magnetic core saturation and improve the magnetic field energy harvesting power by adding capacitor components in the circuit and controlling its series-parallel state. ②There is the best series start time and the best capacitance value of the capacitor module to maximize the harvesting power, which increases at first and then decreases with the increase of the series start time and the capacitance value, respectively. ③When the load voltage is 5～15V, the proposed method can effectively alleviate the core saturation and improve the energy harvesting power, and the lifting effect increases with the increase of the load voltage. When the load voltage is 2～5V, the energy harvesting power is increased by promoting core saturation.④With a primary current of 4A at 50Hz, the proposed method increases the harvesting power by 36.8% to 153.2% under different constant voltage loads studied in this paper.