Researchers from the State Key Laboratory of New Energy Power Systems (North China Electric Power University), Yu De, Fu Chao, Wang Yi, Wang Yanxu, Yang Yuming, in the 24th issue of Journal of Electrical Engineering, 2017, pointed out that the isolation type is reduced. The return power of the bidirectional DC converter is used to improve the conversion efficiency, which is of great significance for the application of the extended isolated bidirectional DC converter in the DC distribution network. Firstly, the working principle of double phase shift control and the principle of inverter return power generation are expounded. The mathematical model of transmission power and power supply side and load side return power is established. The analysis of reducing the return power reduces the current stress and improves the efficiency. effect. Secondly, a minimum return power phase shift control method is proposed. Under the condition of transmitting the same power, compared with the double phase shift control method, the power running point controlled by the method can achieve the minimum return power. Finally, the experimental verification on the built 2kW experimental platform shows that the proposed control method can achieve minimum return power operation under different working conditions, thus effectively reducing current stress and power loss and improving efficiency. As an ideal access method for distributed power supply and energy storage devices, DC distribution network can reduce the power conversion link and filtering device, and has become a research hotspot [1-4]. Isolated bidirectional DC-DC converter (IBDC) has distributed, modular and plug-and-play hardware and software structure [5-8], as the interface circuit between the busbars in the DC distribution network. The voltage level is increased by the series connection technology through the high voltage end, and the parallel power is used at the low voltage end to improve the power level, thereby achieving energy conversion and electrical isolation [9-13]. Isolated bidirectional DC converters currently use phase shift control, mainly Single-Phase-Shift (SPS) [14, 15], Extended-Phase-Shift (EPS) [16, 17], Dual-Phase-Shift (DPS) [18] and Triple-Phase-Shift (TPS) [19, 20] four control modes. Single phase shift control is the most widely used algorithm in IBDC [21, 22]. This control method is simple and easy to feedback. However, it can only adjust the power output of the system by adjusting the single variable, and can not adjust the return power and current stress of the system. . Compared with single phase shift control, extended phase shift control not only expands the Zero Voltage Switching (ZVS) operating range, but also reduces current stress, improves efficiency, and improves adjustment flexibility [23]. The voltage conversion state of the primary and secondary side bridges of the converter under double phase shift control is the same as the power flow direction. Therefore, relative phase shift control is relatively easy to implement, and its dynamic performance is better [23]. In the traditional phase shift control method, IBDC has the disadvantages of excessive peak current and excessive switching stress. A large amount of return power is the main cause of excessive peak current, increased system path loss and lower power transmission efficiency. In order to overcome the above shortcomings, the literature [24] proposed the concept and algorithm of expanding the reflow power under phase shift control, and analyzed the characteristics of the reflow power under different voltage conversion ratio k. By reducing the reflow power, the current stress is reduced. Loss of power devices and magnetic components improves the efficiency of the converter. The minimum reflow power control algorithm for extended phase shift control at k=1 is given in [25]. However, the characteristics and control methods of IBDC's return power under dual phase shift control remain to be studied. In order to reduce the return current and current stress of IBDC, this paper analyzes the return power phenomenon of IBDC under double phase shift control, and establishes the mathematical model of power supply side and load side return power. On this basis, a minimum return power phase shift control method is proposed, and the minimum return power operating point is given. Figure 1 Isolated bidirectional DC converter Figure 9 IBDC experimental platform in conclusion This paper analyzes the power supply side return power and load side return power present in the isolated bidirectional DC converter under dual phase shift control. Based on this, a minimum return power phase shift control method is proposed. Experiments were carried out under different operating conditions of the converter transmission power. Theoretical analysis and experimental results show that: 1) The current stress and peak current of the equal power operating point of the double phase shift control increase as the outer phase shift angle d2 increases. 2) The return power of the equal-power operating point of the double phase shift control on the left side of the minimum return power point decreases as the outer phase shift angle d2 increases, and the return power of the equal power operating point of the right double phase shift control The outer phase shift angle d2 increases and increases. 3) Reducing the reflow power has a significant effect on the reduction of the current stress, but reducing the reflow power of the converter to a minimum does not control the current stress to a minimum. 4) Under the condition of transmitting the same power, compared with the double phase shift control method, the power running point of the minimum return power phase shift control can achieve the minimum return current on the source side and the load side, and the peak current and current stress are significantly reduced, which can be reduced. Small converter losses improve conversion efficiency. The Smart Screen Protector Cutting Machine can help stores reduce the inventory of Screen Protectors. It is mainly used to cut Screen Protectors such as Mobile Phone Screen Protectors, Watch Screen Protectors, Tablet Screen Protectors, Pad Screen Protectors, and personalized fashion Back Films. It is very suitable for personal business or shop drainage. Screen Protector Cutting Machine,Protective Film Cutting Machine,Back Sticker Cutting Machine,Phone Sticker Cutting Machine, Film Cutting Machine Shenzhen Jianjiantong Technology Co., Ltd. , https://www.tpuscreenprotector.com
Universal Screen Protector Cutting Machine has 20000+ cloud data of different specifications and models, adopts massive cloud database, and all data is updated synchronously in the state of networking. You'll have a full range of screen protector models on one machine and cut any Screen Protector model as needed without having to stock up on Screen Protectors for various phone models. No more losing customers due to missing models.