Power Steering Controller Fault Detection via Dual MOSFET Segmentation
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Solution Overview
Problem
Existing power steering controllers fail to detect faults in MOS-FETs and parasitic diodes due to continuous current flow through parasitic diodes, which prevents accurate fault judgment.
Innovation Solution
A controller for power steering apparatus with two switching elements connected in series and parasitic diodes in parallel, equipped with a voltage detecting member to monitor output voltages and a fault judging member to detect faults in both switching elements and parasitic diodes, allowing for accurate fault detection and prevention of overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parasitic diode is mounted in parallel between drain and source of MOS-FET, then current can flow continuously to maintain operation, but fault detection becomes impossible because the diode masks abnormal conditions
Solution Approach 1:
The power supply path is segmented into two separate switching elements connected in series at opposite directions. This segmentation allows independent control and detection of each switching element's state, enabling fault detection while maintaining continuous operation capability through the complementary arrangement.
Solution Approach 2:
A capacitor is introduced as an intermediary component connected to the switching elements. The capacitor enables voltage detection circuitry to monitor the state of switching elements and parasitic diodes without disrupting the continuous current flow, thus allowing fault detection while preserving reliable operation.
2Measurement precision
If two switching elements are connected in series at opposite directions, then fault detection capability is improved, but device complexity increases
Solution Approach 1:
The two switching elements connected in series at opposite directions serve multiple functions: they enable continuous operation through complementary conduction, provide fault detection capability through voltage monitoring, and maintain power supply stability. This multi-functionality justifies the increased device complexity by consolidating multiple objectives into a single configuration.
Data Source
AI summary
The electrical power steering apparatus 10 includes the 1st MOS-FET 13 and the 2nd MOS-FET 14 accommodating the 1st parasitic diode 15 and the 2nd parasitic diode 16 in the conducting path between the battery 100 and the motor driving circuit 11 and being connected in series at the opposite direction respectively, and the condenser 18 in an output side of the latter 2nd MOS-FET 14. The ECU 6 of the controller of the electrical power steering apparatus controls to turn on or off the 1st MOS-FET 13 and the 2nd MOS-FET 14 in accordance with the predetermined sequence after the ignition switch 17 is turned on, detecting the fault of the 1st MOS-FET 13, the 2nd MOS-FET 14 and the 1st parasitic diode 15 and the 2nd parasitic diode 16 on the basis of the output voltage from each of the 1st MOS-FET 13 and the 2nd MOS-FET 14.