Elevator Power Management via Predictive Energy Storage
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Solution Overview
Problem
Conventional elevator systems are inefficient as they dissipate regenerated energy and require oversized components to handle peak power demands, leading to increased costs and reduced efficiency, and are prone to faults during utility voltage sags or failures.
Innovation Solution
A power management system that predicts usage patterns for the elevator hoist motor and sets a target storage state for an energy storage system, controlling power exchange between the hoist motor, primary power supply, and energy storage system to optimize energy usage and reduce demand on the primary power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerated energy is dissipated through a dynamic brake resistor, then the elevator system can handle regenerative power, but the power utility must supply all demand including peak conditions, increasing component size and cost
Solution Approach 1:
The energy storage system pre-stores regenerated energy during periods of low demand, preparing it for use during peak demand periods. This preliminary action allows the power supply components to be sized for average rather than peak demand, reducing component size and cost while eliminating energy dissipation.
Solution Approach 2:
The system changes the temporal distribution of power demand by storing energy during low-demand periods and releasing it during high-demand periods. This parameter change transforms peak power demands into spread-out demands over time, allowing smaller power supply components to handle the same total energy requirement.
2Device complexity
If regenerated energy is dissipated, then the elevator system can operate with simple power management, but system efficiency decreases due to wasted energy
Solution Approach 1:
The energy storage system automatically captures and stores regenerated energy from the elevator motor during downward motion or light load conditions. The controller autonomously manages the charging and discharging cycles based on demand patterns, enabling the system to recycle its own energy without external intervention and significantly improving overall efficiency.
3Reliability
If the elevator system is designed for continuous operation within designated voltage range, then components can operate reliably under normal conditions, but the system faults during utility voltage sags or failures
Solution Approach 1:
The energy storage system pre-charges during normal voltage conditions, creating an energy buffer that cushions the elevator system against future voltage sags or failures. When utility power disturbances occur, the stored energy maintains continuous operation without faults, effectively preparing the system in advance for adverse conditions.
Solution Approach 2:
The energy storage system acts as an intermediary between the utility power supply and the elevator motor. It decouples the motor from direct dependence on utility voltage stability, absorbing voltage fluctuations and providing a buffer that maintains reliable operation during utility disturbances while keeping components within their rated operating ranges.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach maximizes energy storage, reduces the size and cost of power supply components, enhances system efficiency, and ensures continuous operation during power failures by maintaining the energy storage system at a target state, thereby prolonging its longevity.
Implementation Method 1
an energy storage system... A target state of stored energy (or storage state) for the energy storage system is then set based on the predicted usage pattern. Power exchanged between the hoist motor, the primary power supply, and the energy storage system is controlled
Implementation Method 2
Power demand for operating elevators range from positive, in which externally generated power (such as from a power utility) is used, to negative, in which the load in the elevator drives the motor so it produces electricity as a generator. The use of the motor to produce electricity as a generator is commonly called regeneration.
Data Source
AI summary
Power distribution is managed in an elevator system including an elevator hoist motor (12), a primary power supply (20), and—an energy storage system (32). A predicted usage pattern for the hoist motor is established based on past hoist motor power demand in the elevator system or in similar elevator systems in similar buildings. A target storage state for the energy storage system is then set based on the predicted usage pattern. Power exchanged between the hoist motor, the primary power supply, and the energy storage system is controlled to address power demand of the hoist motor and to maintain the storage state of the energy storage system at about the target storage state.