Xiaozhong Qi

The evolution of electronic technology has intensified the demand for lithium-ion batteries to achieve elevated energy density, prolonged cycling longevity, and enhanced safety. Traditional graphite anodes are inadequate in meeting these requirements. α-Fe₂O₃ possesses a high theoretical capacity and is abundantly available; however, its poor conductivity and significant volume expansion during charge–discharge cycles restrict its practical applicability. This study addresses these issues by developing a three-layer cooperative structural anode material composed of foam nickel (NF), α-Fe₂O₃, and polypyrrole (PPY). Employing a hydrothermal method, α-Fe₂O₃ nanowires were in-situ grown on the 3D framework of foam nickel, followed by electro-polymerization to achieve a dense PPY coating. The foam nickel offers a highly conductive scaffold and mechanical support, while PPY enhances conductivity, provides structural buffering, and facilitates in-situ nitrogen doping. Collectively, these components synergistically improve conductivity, mitigate volume expansion, and optimize the solid electrolyte interphase. This composite material demonstrates comprehensive enhancements in conductivity, structural stability, and interface compatibility, as evidenced by the well-preserved structural integrity after prolonged cycling, thereby overcoming the performance limitations associated with singular α-Fe₂O₃ and simplistic composite systems, and presenting novel insights and technical support for the advancement of high-energy-density lithium-ion battery anodes.

This paper studies the speed regulation simulation of permanent magnet synchronous motor. First, this paper analyzes the mathematical model of permanent magnet synchronous motor, and studies the control strategy of Id = 0, maximum torque-current ratio and weak magnetic leading Angle under synchronous rotation coordinate system. Secondly, the control strategy model is established on MATLAB/SIMULINK platform, including coordinate transformation, space vector pulse width modulation (SVPWM), proportional integration regulator, three-phase inverter, MTPA, weak magnetic core control algorithm module. Meanwhile, an APP for real-time monitoring of motor simulation model operation, control and parameter adjustment is designed by using APP Designer toolbox. Finally, the start and stop, speed increase and decrease, load surge torque and motor high-speed operation of the electric motorcycle PMSM are simulated in the actual operation. The experimental results show that the system has strong response ability and anti-interference ability under the control of current and speed PI regulator. In the motor start-stop state, the MTPA control strategy can distribute large electromagnetic torque during start-up, effectively improve the efficiency of the inverter and save costs. Compared with MTPA and Id = 0 control strategies, weak magnetic control has excellent speed increase effect, up to 6000r/min, and has strong anti-interference ability. Through the control method of the leading Angle, the dynamic switching between MTPA and weak magnetic control strategy is realized, and the running speed range of PMSM is effectively extended.