Flywheel UPS Passive Rectifier Active Inverter Cost Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flywheel UPS systems require expensive full-power active components for power conversion, and high switching frequencies increase costs due to inefficiencies in existing power conversion components.
Innovation Solution
A system with a flywheel coupled to a motor/generator, using a passive rectifier and active inverter for power conversion, where the motor drive has a lower power rating than the passive rectifier and active inverter, and operates at a lower switching frequency to minimize costs and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-power active components are used for power conversion in flywheel UPS systems, then power quality requirements are met, but system cost increases significantly
Solution Approach 1:
The patent segments the power conversion function into two separate stages: a passive rectifier stage for AC-to-DC conversion and an active inverter stage for DC-to-AC conversion. This segmentation allows each component to be optimized independently, with the passive rectifier handling bulk power conversion and the active inverter providing power quality regulation, thereby reducing overall system cost while maintaining reliability.
Solution Approach 2:
The patent introduces a DC bus as an intermediary energy storage element between the passive rectifier and active inverter. This DC bus acts as a buffer that decouples the rectifier and inverter operations, allowing the use of simpler passive rectification components while maintaining the ability to provide regulated AC output through the active inverter stage.
2Loss of energy
If high switching frequency is used in bidirectional converter, then flywheel losses are minimized, but component cost and complexity increase
Solution Approach 1:
The patent employs periodic action by using high-frequency switching only during transient conditions when the flywheel needs to exchange energy with the DC bus, rather than continuous high-frequency switching. During steady-state operation, the system operates at lower frequencies, reducing component stress and complexity while still achieving low losses when needed.
Solution Approach 2:
The patent changes the operating parameters of the power conversion system dynamically. The active inverter switches at high frequency only when power transfer is required between the flywheel and grid, while operating at lower frequencies during idle periods. This parameter change approach minimizes flywheel losses during critical operations without requiring continuously high-frequency switching components.
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 configuration reduces the cost of power conversion by using less expensive components and minimizing losses, while maintaining efficient power delivery to the load during grid failures.
Implementation Method 1
A passive rectifier is coupled to the flywheel system for converting alternating current generated by the flywheel system to direct current
Implementation Method 2
An active inverter is coupled to the passive rectifier for converting the direct current from the passive rectifier to alternating current
Implementation Method 3
a flywheel coupled to rotate with a motor/generator
Implementation Method 4
The flywheel system includes a flywheel coupled to rotate with a motor/generator
Data Source
AI summary
A flywheel interface system for line interactive power correction comprises a flywheel system that includes a flywheel coupled to rotate with a motor/generator. A passive rectifier is coupled to the flywheel system for converting alternating current generated by the flywheel system to direct current. An active inverter is coupled to the passive rectifier for converting the direct current from the passive rectifier to alternating current and to output the alternating current to the load. A motor drive is coupled to the motor/generator of the flywheel system for driving the motor/generator to rotate the flywheel, the motor drive including a second passive rectifier coupled to a second active inverter.