Cascade Flywheel Doubly-Fed Machine Energy Recovery
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Solution Overview
Problem
Conventional energy transfer systems with flywheels and vehicle drive motors suffer from significant electrical loads on power devices, DC capacitors, and batteries, leading to energy losses as all energy must pass through these components during energy transfer.
Innovation Solution
A kinetic energy recovery system with a cascade flywheel doubly-fed electric machine and an electric motor, where the main phase coil of the flywheel and the phase coil of the motor are directly connected in series, allowing energy to bypass power electronics and DC capacitors, reducing energy flow through these components and enabling efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If all energy passes through power electronics, DC capacitors, and batteries during energy transfer, then energy transfer can be achieved, but significant electrical loads are imposed on these components causing energy losses
Solution Approach 1:
The energy transfer path is segmented into two separate paths: one for high-power energy transfer between the drive motor and grid through the flywheel, and another for low-power control signals through the power electronics. This segmentation allows the majority of energy to bypass the power electronics, reducing their electrical load and associated energy losses.
Solution Approach 2:
The flywheel acts as an intermediary energy storage device between the drive motor and the grid. It absorbs excess regenerative energy during braking and releases it during acceleration, mediating the energy transfer and preventing it from passing through the power electronics and batteries, thereby reducing electrical loads and energy losses.
2Power
If power electronics and DC capacitors handle all energy transfer, then complete energy transfer is achieved, but these components must withstand high power causing losses
Solution Approach 1:
The system segments the power handling requirements by assigning the flywheel to handle high-power energy transfer directly between the motor and grid, while the power electronics handle only low-power control functions. This segmentation reduces the power handling burden on the power electronics and DC capacitors, minimizing energy losses.
Solution Approach 2:
The high-power energy transfer function is extracted from the power electronics and DC capacitors and assigned to the flywheel. This extraction allows the power electronics and capacitors to operate at lower power levels, reducing their energy losses while maintaining complete energy transfer capability through the flywheel.
3Loss of energy
If the flywheel and motor phase coils are directly connected in series, then energy can bypass power electronics, but the system configuration becomes more complex
Solution Approach 1:
The flywheel doubly-fed electric machine is designed with multi-functionality, serving both as an energy storage device and as a direct energy transfer path. Its phase coils can be directly connected to the motor, eliminating the need for separate power electronics for high-power transfer, thus reducing energy losses without proportionally increasing system complexity.
Solution Approach 2:
The flywheel doubly-fed electric machine merges multiple functions into a single component: energy storage, direct energy transfer to the motor, and grid connection. This merging allows the phase coils to be directly connected in series with the motor, creating an efficient energy path that bypasses power electronics while maintaining manageable system complexity through functional integration.
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 energy losses by allowing power electronics and DC capacitors to handle lower power levels, enabling efficient energy recovery and transfer while sharing load on the DC bus side, thus enhancing energy recovery and reducing system losses.
Implementation Method 1
The flywheel can store kinetic energy by increasing speed or releasing kinetic energy by decreasing speed
Implementation Method 2
The rectifier converts alternating current to direct current, so that the inverter can draw power from the DC bus
Implementation Method 3
The inverter is used to supply alternating current to the rotor end coil
Implementation Method 4
When the cascaded flywheel double-fed electric machine decelerates, the kinetic energy recovery system with flywheel will convert mechanical energy into electrical energy
Data Source
AI summary
A kinetic energy recovery system with flywheel includes a cascade flywheel doubly-fed electric machine and an electric motor. The cascade flywheel doubly-fed electric machine has a stator end coil, a rotor end coil and a flywheel. The flywheel can store kinetic energy by increasing speed or releasing kinetic energy by decreasing speed. A control circuit has an inverter, a rectifier and a DC bus connecting the inverter and the rectifier. The inverter supplies alternating current to the rotor end coil. The rectifier has an AC end connected to the stator end coil through an AC bus. The rectifier converts alternating current to direct current, so that the inverter can draw power from the DC bus. The electric motor has a phase coil connected to the AC bus. When the cascade flywheel double-fed electric machine decelerates, the system converts mechanical energy into electrical energy.