System and method for managing a current flow in a lift machine

摘要

There is provided an energy management system for managing a current flow in a machine having a lift element being vertically movable by a motor assembly. The energy management system includes a power supplying bus for supplying the motor assembly, a battery source, an energy storage device and an associated controller, and a main controller for controlling the energy-storage-device controller and thus the powering of the motor assembly, while factoring a height and a movement of the lift element. The system generally seeks to manage the energy flow between the battery, motors and supercapacitors so as to maintain the battery current as low as possible by controlling the motor's speed, to maintain the battery power demand constant over time, and to store the regenerated energy into supercapacitors in order to avoid recharging the battery during operation, as well as to maintain the supercapacitors energy level as high as possible.

主权项

1. An energy management system for managing a current flow in a machine having a lift element being vertically movable by a motor assembly, the energy management system comprising:
a power supplying bus for supplying the motor assembly; a battery source being connected to the power supplying bus; an energy storage device; an energy-storage-device controller connected between the energy storage device and the power supplying bus, for controlling a current flow between the energy storage device and the power supplying bus; sensors for detecting a height H and a movement of the lift element, said movement being selected from the group consisting of a lifting movement, a lowering movement and an immobile movement; a first calculator connected to the sensors for calculating a minimum energy Emin required in the energy storage device as a function of the height H of the lift element; a second calculator connected to the energy storage device for calculating an energy Eavailable stored in the energy storage device based on a voltage Vcap detected at terminals of the energy storage device and on a parameter of the energy storage device; a comparator for calculating an Error where Error=Emin−Eavailable; a third calculator for setting a lower limit Imin of a current to be drawn from the energy storage device to 0 A when the movement detected by the sensors is the immobile or lowering movement, and for calculating the lower limit Imin as a function of Error when the movement detected by the sensors is the lifting movement; a fourth calculator for calculating an upper limit Imax of a current to be supplied to the energy storage device as a function of Error when the movement detected by the sensors is the immobile or lowering movement; and a main controller for controlling the energy-storage-device controller as a function of Imin, Imax, and the movement detected, to adjust the current flow between the energy storage device and the power supplying bus.