Motor Controller Integrated Solid-State Contactor
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Solution Overview
Problem
High current electromechanical contactors in battery-powered vehicles are prone to failures due to corrosion, freezing, and vibration, and are costly, while commercially available solid-state contactors are prohibitively expensive for high current applications.
Innovation Solution
Integration of solid-state circuits with motor controllers, using back-to-back FETs or single direction blocking FETs to provide current protection, and incorporating a capacitor discharge circuit and logic power circuits, along with a main power fuse, to replace electromechanical contactors, reducing component count and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromechanical contactors are used to disconnect motor controller from battery, then cost is reduced and high current handling is achieved, but reliability deteriorates due to contact corrosion, freezing, and vibration
Solution Approach 1:
The patent integrates the contactor function directly into the motor controller by incorporating FETs (Field Effect Transistors) as solid-state switching elements within the controller housing. This merging eliminates the need for a separate electromechanical contactor, thereby improving reliability by removing vulnerable moving parts while reducing overall system complexity through component consolidation.
Solution Approach 2:
The patent replaces the electromechanical contactor system with a solid-state FET-based switching system. The FETs provide electrical switching functionality without mechanical moving parts, contacts, or arc suppression mechanisms, thereby eliminating reliability issues related to contact corrosion, freezing, and vibration while maintaining high current handling capability.
2Reliability
If solid state contactors are used to replace electromechanical contactors, then reliability is improved and maintenance is eliminated, but cost increases prohibitively for high current applications
Solution Approach 1:
The patent combines the contactor function with the motor controller into a single integrated unit. By sharing the FETs and heat sinking resources between the contactor switching function and the motor controller's motor driving function, the manufacturing cost is reduced to a fraction of traditional discrete solid-state contactors while maintaining high reliability benefits.
Solution Approach 2:
The FETs integrated into the motor controller serve dual purposes: they function as both the contactor switching elements for battery disconnection and as the power switches for motor control. This multi-functionality eliminates the need for dedicated contactor components, significantly reducing manufacturing cost while preserving reliability improvements.
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
The solution provides a cost-effective, reliable, and safe alternative to electromechanical contactors by integrating solid-state contactors with motor controllers, reducing heat sinking needs and eliminating additional cabling, while meeting safety standards at a fraction of the traditional solid-state contactor cost.
Implementation Method 1
In an off-state, the FETs are operable to block current flow from the battery to the motor controller
Implementation Method 2
the FETs are thermally coupled to a heat sink of the motor controller
Data Source
AI summary
Circuits, systems, and methods are disclosed to eliminate the requirement for an external electromechanical contactor. Integrating contactor circuits with a motor controller reduces cost. Additionally, the cost of the contactor circuit may be reduced by providing transistors designed to block current in only one direction in the event of an electrical fault corresponding to an electrical drive direction.