A New Method of Elevator Emergency Leveling Based on Supercapacitor Energy Storage

A new method of using supercapacitor energy storage to realize elevator emergency leveling is proposed. The supercapacitor is connected to the DC bus of the inverter through a series current limiting device for online charging and discharging. When the elevator encounters an abnormal power failure, the four-quadrant inverter converts the DC power provided by the supercapacitor into a back-to-back power supply. The elevator system can be powered on again, and the emergency leveling action can be completed without changing the original control logic. During the normal operation of the elevator, the four-quadrant frequency converter can recover and reuse the regenerative energy. Considering the drive loss of the frequency converter, electromechanical conversion loss of the asynchronous motor, and mechanical transmission loss of the planetary gearbox, the parameters of the supercapacitor are selected through the energy supply and demand balance analysis. Finally, through the actual application scenario, a simulation model based on MATLAB is established. The transient simulation analysis results of the emergency switching process show that the supercapacitor power supply enables the elevator to complete the 4m downward emergency leveling action under extreme operating conditions and provides a stable AC power supply with an amplitude of 320.4V and a harmonic rate of 6.09% to other loads on the grid side.