Research On Supercapacitor-Based Energy Saving Key Technology For Elevator

The elevator will produce large amounts of energy in generating process, but the traditional schemes, such as energy-consumption and energy-inverter, have energy wasting and harmonic pollution problems, so feedback energy can not be used reasonably. This paper proposes a method based on supercapacitor elevator energy-saving system.In this system, supercapacitor was parallelled in DC bus through bidirectional DC/DC so it costs fewer number of supercapacitors, needing lower cost, which can also supply peak power that generated in starting and braking period.Braking unit and resistance parallelled in DC bus are used to consume excess energy when supercapacitor is charged fully.In order to analyze every part of the energy-saving system ,we have established a simulation model by Matlab/Simulink, containing supercapacitor , bidirectional DC-DC, frequency converters ,traction motor and elevator load.The simulation model intuitively reflects charge and discharge current ,terminal voltage, power and so on ,which lays a foundation for the subsequent parameters matching and control strategy researching.On the base of having analyzing the operation performance of elevator, we proposes a matching scheme including supercapacitor , bidirectional DC/DC, braking resistor,which can meet power energy demanding and save the cost. The control strategy of established system has able to judge the traction machine's working condition according to DC bus and supercapacitor voltage, and for the need of controling supercapacitor to charge/discharge action, we also put forward an supercapacitor current control strategy considering DC/DC efficiency ,power system cost and grid impact.Bidirectional DC-DC is the core of energy-saving elevator system, and its topology is Buck/boost structure,which is simple and convenient to apply resonance technology and is suitable for high-power situation , it can easily realize the two-way flowing of energy. On this paper we have hard/software designed for bidirectional DC/DC.In order to control the charging and discharging state of supercapacitors, this paper designs the hard/software of energy management unit. ARM LPC2119 acts as a control core chip of energy management unit .Signal power of frequency converter is collected through the 485 communication, and by using of CAN, system realizes the DC/DC communication control and the two-way flowing of energy .In order to construct the platform of the supercapacitor energy-storage elevator energy-saving system, we use two motors to drag each other for simulating elevator conditions .Finally, we take experiments in the system platform. It realizes that conditions of elevator by using of ARM LPC2119 and runs the control strategy of the experiment through elevator energy management unit in experimental platform. The experimental results show that the correctness of parameters matching and the control strategy.