Abnormality Detection Device for Electric Power Steering
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Solution Overview
Problem
Conventional abnormality detection devices in electric power steering systems face challenges in efficiently detecting short-circuit and open-circuit failures of motor relays and disconnection failures of phase windings due to increased mounting size and heat generation issues related to voltage monitoring resistors.
Innovation Solution
The proposed abnormality detection device incorporates an inverter with high-side and low-side switching elements, motor relays, pull-up and pull-down resistors, and a checking unit to monitor terminal voltages, with the driver circuit IC housing the pull-up resistor to minimize mounting area and reduce heat generation by stopping high-side FET operations during detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage monitoring resistors are added to detect relay and winding failures, then detection capability is improved, but mounting size increases
Solution Approach 1:
The pull-up resistor is integrated inside the driver circuit IC package rather than being mounted separately on the circuit substrate. This merging of components reduces the overall mounting area while maintaining the voltage monitoring function for detecting relay and winding failures.
Solution Approach 2:
The driver circuit IC is designed to serve multiple functions: it drives the switching elements and simultaneously performs abnormality detection through the integrated pull-up resistor. This multi-functionality eliminates the need for separate dedicated monitoring components, reducing mounting size.
2Reliability
If voltage monitoring resistors are added to detect relay and winding failures, then detection capability is improved, but heat generation increases
Solution Approach 1:
By integrating the pull-up resistor within the driver circuit IC package, the patent reduces the total number of discrete components and their associated parasitic elements. This consolidation minimizes overall heat generation while maintaining effective voltage monitoring capability for failure detection.
3Area of stationary object
If pull-up resistor is integrated in driver circuit IC, then mounting area is reduced, but device complexity increases
Solution Approach 1:
The pull-up resistor is integrated inside the driver circuit IC package, combining multiple functions (driving switching elements and performing voltage monitoring) into a single component. This reduces the number of separate components on the circuit substrate, simplifying the overall system layout and reducing mounting area.
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 effectively reduces the mounting size of the ECU, minimizes heat generation, and accurately detects short-circuit and open-circuit failures, enhancing reliability in electric power steering systems with limited space.
Implementation Method 1
Each pull-up resistor connects the power supply line and the inter-arm connection point of each phase. Each pull-down resistor connects the inter-arm connection point of each phase and the ground. A checking unit is configured to acquire a voltage corresponding to a voltage of the inter-arm connection point of each phase as a terminal voltage
Data Source
AI summary
Driver circuits are provided in correspondence to switching elements of an inverter to output gate signals to the switching elements and built in an IC package in an abnormality detection device (ECU). Motor relays are provided in motor current paths between inter-arm connection points and multi-phase motor windings. Pull-up resistors connect a power supply line and the inter-arm connection points. Pull-down resistors connect the inter-arm connection points and the ground. A checking unit acquires a voltage corresponding to a voltage of each inter-arm connection point as a terminal voltage and checks a short-circuit failure or an open-circuit failure of each motor relay or a disconnection failure of each winding based on the terminal voltage. The pull-up resistors and the pull-down resistors are provided within the IC package in which the driver circuits are built.