Research On Regenerative Elevator Driver With Super-Capacitor Module

Since the start of21st century, the requirement of life quality and production efficiency has increased dramatically, with China’s rapid economic development. As a result, the elevator system has a greater usage and growth potential in high-rise buildings and large modern factories. However, the advanced elevator-control technology is mainly dominated by Koreans and Americans. Therefore, the research of our own elevator technology means a lot to China’s sustainable economic development. Meanwhile, a better study of the energy-saving elevator system based on the large holdings and increase is of a great help to reduce energy consumption, carbon emissions, and maintain the sustainable economic development. This paper has made an in-depth study of some key technologies of the regenerative elevator with super-capacitor-based energy storage system, based on the elevator testing tower and hardware platform.Firstly, a distributed auxiliary power solution is proposed to meet the elevator driving system requirements and to reduce the EMI, after some comparison of other topologies. Meanwhile, a full-soft-switch forward is proposed as the front-end converter of the auxiliary power. The proposed converter overcomes the limit of50%duty cycle, and realizes the ZVZCS on main switches and diodes within the input voltage from200to400V, with a clamp circuit and resonant circuit. The experimental results show that the efficiency is much higher than the traditional forward converter.Secondly, the reason why a traditional PI controller cannot achieve a good start-hover of elevator car is found, after the analysis of the motor angular displacement and velocity nonlinear caused by the limit of encoder resolution. It leads to a large slip-distance, and even vibrations caused by the limit cycle, in some cases. To solve the problem, the start-hover friction mathematics model is established, and a new nonlinear controller is proposed, whose gain coefficient is adjustable according to the velocity and displacement. The global stability is proved by Lyapunov method. Compared to the traditional PI controller, the proposed nonlinear controller has a smaller overshoot, and a less adjust time, and a shorter slip distance. And the passenger would feel more comfortable due to the continuous variation of the control torque.Thirdly, the grid quality is poor in the industrial field, which has a great influence on the elevator driving system. To overcome this, a new quadrature-signal-generator (QSG) is proposed, which has two inputs based on the traditional SOGI-FLL (dual input SOGI-FLL, DISOGI-FLL). The analysis of the state-space equations of the DISOGI-FLL shows a much better dynamic response in amplitude and frequency track. The global stability of the system is proved by Lyapunov method, and the frequency convergence rate range is achieved, too. Based on this QSG, a single-phase synchronous method and a three-phase synchronous method are developed respectively. By multi-module expansion, harmonics are tracked as well. The simulation and experimental shows that, the convergence time is reduced by50%compared to traditional methods.Finally, studies show that the grid is most vulnerable to the impact of0.01to1Hz power fluctuation, which is the main power fluctuation frequency of the regenerative elevator. To improve the power quality, a power model of the elevator is proposed, and with the help of the super-capacitor module, the constant power controller is achieved to eliminate the power fluctuation. To realize a better effect, an adaptive estimator is designed by the super-capacitor terminal voltage as the reference error, and the super-capacitor voltage would remain the same before and after a run cycle, by addition. Compared with traditional way, the proposed controller removes75%power fluctuation.