Research On Elevator Energy Saving Method Of Super Capacitor Collaborative Control

With the development of domestic elevator industry, and the quantities of elevator in use increasing year by year, the ratio of elevator energy consumption accounting for total electricity grows gradually. As a load of potential energy, elevator starts and stops frequently, so it has a huge saving space when it runs.There are two kinds of energy saving ways in research. The first, the feedback energy of elevator is sent to the grid, namely the traction machine sends feedback energy to the inverter DC bus side, and then the feedback energy is converted to the same frequency and the same phase power sent to the grid. The other is super capacitor energy storage type. Namely the inverter DC bus is connected to super capacitor through bidirectional DC/DC converter. The bidirectional DC/DC converter works depends on the running state of elevator, then the operation state of super capacitor is determined. The second energy saving device can absorb and use feedback energy efficiently and reduce impact to the grid result from elevator starting. Because it needn't sent feedback energy to the grid, the power quality problem by feedback energy can be avoided. What's more, the energy saving device of super capacitor can be used as UPS, which can provide energy for elevator completing emergency lighting and running to the nearest floor in case of elevator suddenly loses power.The advantages and disadvantages of two kinds of bidirectional DC/DC converter are analyzed. The isolation bidirectional DC/DC converter is used in this paper according to the wide range of voltage and the low cost of super capacitor. On this basis, the method of realizing PWM soft switch is analyzed respectively in the boost and buck model of bidirectional DC/DC converter. According to the topological structure of bidirectional DC/DC converter, a small signal analysis model is set up by the small signal analysis method. Then the double closed loop PI control method of the charging and discharging current of the super capacitor inner loop and the inverter DC bus voltage outer loop is adopted. Energy saving elevator simulation model based on the super capacitor is built in Matlab/Simulink. Two working states of energy feedback and energy consumption of elevator are simulated to show the feasibility and effectiveness of the energy saving method.Finally, the method of the design parameters of bidirectional DC/DC converter and super capacitor selection are given. The determination method of elevator energy consumption is also proposed. The reference stroke method is used to compare and analysis elevator energy consumption and elevator energy saving.