Variable Flux Bridge Rotor for Electric Machine Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric machines in electrified vehicles face challenges in achieving high power outputs and efficient thermal management due to limitations in the interaction between stator cores and rotors, leading to suboptimal torque output and increased stator core losses.
Innovation Solution
The electric machine assembly incorporates a rotor with a variable flux magnet and pairs of magnets arranged to control torque output, using a trapezoidal-shaped variable flux magnet and side flux barriers to manage magnetic flux, allowing for adjustable torque production and reduced stator core losses by diverting magnetic flux along horizontal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional magnet arrangements are used in the rotor, then the structure is simple, but torque output variability and efficiency are limited
Solution Approach 1:
The patent applies dynamics by making the magnetic flux variable rather than fixed. The variable flux magnet embedded in the bridge allows the magnetic field to be dynamically adjusted during operation, enabling torque output variability while maintaining a relatively simple physical structure. The magnet can change its magnetic properties in response to operational conditions.
Solution Approach 2:
The patent applies local quality by creating different magnetic flux paths through strategic placement of flux barriers and variable flux magnets. Different regions of the rotor are given different magnetic properties - some areas have high flux density while others have low flux density, allowing optimized torque production in different zones without requiring complete structural complexity throughout.
2Power
If magnetic flux is allowed to flow freely between stator and rotor, then power output can be high, but stator core losses increase
Solution Approach 1:
The patent applies segmentation by dividing the magnetic flux path into distinct segments using flux barriers. The barriers segment the rotor structure into regions with different flux densities, allowing the magnetic flux to be controlled and directed through specific paths. This segmentation enables high power output through optimized flux paths while reducing losses by preventing excessive flux penetration into the stator core.
Solution Approach 2:
The variable flux magnet embedded in the bridge acts as an intermediary element between the permanent magnets and the stator core. It mediates the magnetic flux interaction, allowing controlled flux transfer that maintains high power output while minimizing harmful flux paths that would cause stator core losses.
3Manufacturing precision
If D-axis current is increased to control magnetization, then magnetization control improves, but overall efficiency decreases due to increased losses
Solution Approach 1:
The patent applies preliminary action by pre-configuring the magnetic circuit with flux barriers and variable flux magnets to establish optimal flux paths before operation. This preliminary structural arrangement reduces the need for high D-axis currents during operation, as the magnetic circuit is already optimized for efficient flux distribution, thereby reducing copper losses while maintaining precise magnetization control.
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 enhances torque output variability and efficiency by optimizing magnetic flux distribution, enabling high torque production while minimizing stator core losses, thus improving the electric machine's performance across different drive cycles.
Implementation Method 1
The variable flux magnet is embedded in the bridge and located on the rotor to influence current associated with the Q-axis to control torque output of the rotor
Implementation Method 2
The variable flux magnet is embedded in the bridge and located on the rotor to influence current associated with the Q-axis to control torque output of the rotor, and to pulse D-axis current to control a magnetization of the bridge
Implementation Method 3
The side flux barriers may be arranged with the variable flux magnet to prevent vertical current or flux associated with the Q-axis from influencing magnetization of the variable flux magnet
Implementation Method 4
The first side flux barrier and the second side flux barrier may each be located to influence magnetic flux to flow in a substantially horizontal path through the variable flux magnet
Implementation Method 5
The first pair of magnets are arranged with one another to generate current along a first D-axis when the rotor is rotating and the stator core is activated
Data Source
AI summary
An electric machine assembly for an electrified vehicle including a stator core, a rotor, a first pair of magnets, a second pair of magnets, and a variable flux magnet is provided. The stator core defines a cavity. The rotor is disposed within the cavity for rotation and includes a bridge. Each of the first pair of magnets may be mounted to the rotor and spaced from one another on either side of a first D-axis. Each of the second pair of magnets may be mounted to the rotor and spaced from one another on either side of a second D-axis. The first D-axis and the second D-axis are spaced from one another on either side of a Q-axis. The variable flux magnet is embedded in the bridge and located on the rotor to influence current associated with the Q-axis to control torque output of the rotor, and to pulse D-axis current to control a magnetization of the bridge.