Regenerative Braking in an Elevator Using Supercapacitor

Nowadays, for the development of regenerative drive system for the elevators, power and energy variation are the main motivations. So, there is a need to save energy which is wasted during normal operating condition of elevator. Aim of this paper is to adjust the acceleration and deceleration rate and speed for maximizing the regenerative capability of the drive system and hence to improve the elevator efficiency. At the time when the elevator machine operates as the generator, the energy due to braking is accumulated in a supercapacitor bank for temporary storage purpose and when the elevator machine operates in motoring mode the braking energy can be reused. Whatever the energy generated during braking is either returned back to the grid via converter or accumulated in a supercapacitor for further use in motoring operation. The proposed system has been simulated in a MATLAB. For charging the supercapacitor, the charging circuit model is prepared using PWM technique.