Brushless Permanent Magnet Motor for Hybrid Starter
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Solution Overview
Problem
Brushed starter motors in hybrid vehicle propulsion systems face issues with physical contact wear, reduced torque near high speed ranges, and sequential solenoid actuation leading to time delays and voltage drops, which increase complexity and cost.
Innovation Solution
A brushless permanent magnet DC motor powered by a high-voltage traction battery, eliminating physical contact wear and using solid-state switches for electronic commutation, reducing rotor inertia and eliminating the need for additional power sources or solenoids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact brushes are used to conduct current between stator and rotor, then current conduction is achieved, but physical contact wear occurs leading to motor degradation
Solution Approach 1:
The patent replaces the mechanical contact brush system with a brushless permanent magnet electric machine that uses electromagnetic induction for current conduction. The stator windings generate a rotating magnetic field that interacts with permanent magnets on the rotor, eliminating physical contact and associated wear, thereby improving reliability and extending motor lifespan.
Solution Approach 2:
The invention changes the operational parameters by eliminating the mechanical contact interface entirely. Instead of using sliding contact brushes, the system uses a brushless design with permanent magnets and electromagnetic windings, fundamentally changing how current is conducted from stator to rotor without physical wear.
2Force
If a brushed motor is used, then current conduction is achieved, but torque delivery is substantially zero near the upper bound of speed range
Solution Approach 1:
The patent changes the motor design parameters by using permanent magnets on the rotor instead of brushed commutation. This allows the motor to maintain high torque delivery across the entire speed range, including near the upper bound, by utilizing the persistent magnetic field from permanent magnets that interacts efficiently with the stator's rotating magnetic field.
3Ease of operation
If sequential solenoid actuation is used for starter motor engagement, then mechanical coupling is achieved, but time delays and voltage drops occur increasing complexity
Solution Approach 1:
The patent extracts and eliminates the sequential solenoid actuation system from the starter motor design. The brushless permanent magnet electric machine provides direct electromagnetic coupling between stator and rotor through the magnetic field, removing the need for mechanical solenoids and their associated sequential actuation, time delays, and voltage drops, thereby simplifying the system.
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
Enables rapid engine restarts, reduced noise and vibration, and improved responsiveness with increased motor lifespan and precise speed control, while simplifying the system by eliminating the need for voltage stabilization and sequential solenoid actuation.
Implementation Method 1
a brushless permanent magnet DC motor powered by a high-voltage traction battery, eliminating physical contact wear and using solid-state switches for electronic commutation
Implementation Method 2
a conductive winding wrapped around each of the teeth of the stator to receive an electrical current
Data Source
AI summary
An interior permanent magnet electric machine includes a stator having a plurality of teeth disposed around a circumference oriented radially towards a center defining slots interposed between each of the teeth, and a conductive winding wrapped around each of the teeth of the stator to receive an electrical current. The electric machine also includes a rotor which is rotatable relative to the stator. The rotor defines a plurality of openings to receive permanent magnets near an outer portion of the rotor and a number of spokes interposed between mass reduction cutouts located closer to the center relative to the permanent magnets. Each of the permanent magnets defines a magnetic pole and each of the spokes is circumferentially aligned with one of the magnetic poles.