Electric Power Steering Boost Circuit Fault Detection
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Solution Overview
Problem
In electric power steering apparatuses, the existing shunt circuit for detecting faults in high-power outputs is bulky and costly, making it difficult to reduce component size and cost, especially in vehicles where space and efficiency are critical.
Innovation Solution
A simpler configuration using a boost circuit and voltage detecting means to detect abnormal voltage drops in the auxiliary power supply, allowing for fault detection without a dedicated shunt resistor, and shutting off current to the output destination through a relay switch and switching means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shunt circuit with a shunt resistor is used to detect faults in high-power output, then fault detection capability is improved, but the size and cost of the power supply increases
Solution Approach 1:
The invention extracts the fault detection function from the traditional shunt circuit configuration and implements it through voltage detection of the auxiliary power supply output. By monitoring voltage drops across the auxiliary power supply terminals instead of inserting a shunt resistor in series with the load, the system achieves fault detection without adding bulky current-sensing components to the power supply structure.
Solution Approach 2:
The voltage detecting means serves multiple functions: it monitors the output voltage of the auxiliary power supply for fault detection, and simultaneously provides information for controlling the boost circuit operation. This multi-functionality eliminates the need for separate dedicated fault detection circuits, reducing overall system complexity and size.
2Reliability
If a shunt circuit with a shunt resistor is used to detect faults in high-power output, then fault detection capability is improved, but the cost of the power supply increases
Solution Approach 1:
The invention removes the expensive shunt resistor component from the fault detection system and replaces it with voltage sensing circuitry that leverages existing power supply nodes. This extraction of the current-sensing element eliminates the need for high-power-rated shunt resistors, significantly reducing component costs while maintaining fault detection functionality.
Solution Approach 2:
Instead of directly measuring current through a shunt resistor, the system creates an electrical equivalent measurement by detecting voltage drops across the auxiliary power supply terminals. This voltage-based copying of current information provides the same fault detection capability without requiring physical current-sensing components.
3Power
If main power supply alone is used, then system simplicity is maintained, but power output is insufficient for large vehicles during stationary steering
Solution Approach 1:
The invention merges the main power supply and auxiliary power supply into a unified power delivery system where the auxiliary power supply supplements the main power supply during high-demand conditions. The boost circuit acts as a bridge, transferring energy from the main power supply to charge the auxiliary power supply, creating a combined high-capacity power source that maintains system simplicity through integrated control.
Solution Approach 2:
The auxiliary power supply is pre-charged by the boost circuit from the main power supply before high-power demand occurs. This preliminary energy storage in the auxiliary power supply enables immediate delivery of high current during stationary steering operations without requiring the main power supply to continuously operate at maximum capacity, thereby managing peak power demands efficiently.
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 approach reduces the size and cost of the power supply while effectively detecting faults and shutting off current to prevent damage, eliminating the need for additional components and minimizing heat generation and power loss.
Implementation Method 1
a boost circuit that charges the auxiliary power supply by boosting an output voltage of the main power supply and applying the boosted output voltage to the auxiliary power supply
Implementation Method 2
voltage detecting means for detecting an output voltage of the auxiliary power supply
Data Source
Figure 1
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AI summary
An electric power steering apparatus (1) includes a power supply (20) and a power supply management unit (30) that controls an operation of the power supply (20). The power supply (20) includes a main power supply (17), an auxiliary power supply (18) connected in series to 'the main power supply (17), a boost circuit (33) that charges the auxiliary power supply (18) by boosting an output voltage (V1) of the main power supply (17) and applying the boosted output voltage to the auxiliary power supply (18), and a voltage sensor (37) that detects an output voltage (V2) of the auxiliary power supply (18). When a reduction amount per unit time of the output voltage (V2) detected by the voltage sensor (37) exceeds a voltage reduction amount (?Vmax) over a predetermined time, the power supply management unit (30) determines that an abnormality has occurred in an output destination of the power supply (20).