Electric Power Steering Motor Detection Sleep Wake Cycle
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Solution Overview
Problem
Existing electric power steering apparatuses consume excessive electricity when detecting the rotational quantity of an electric motor even when the main power supply is off, leading to increased battery drain and potential errors in calculating the absolute steering angle.
Innovation Solution
Incorporating a rotational quantity detection unit that enters a sleep state when the main power supply is off and transitions to a wake-up state only when a counter electromotive voltage condition is met, allowing detection of the rotational quantity of the electric motor only when the steering wheel is operated, thereby reducing unnecessary electricity consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotational quantity detection unit continuously detects the rotational quantity of the electric motor even when the main power supply is off, then the absolute steering angle calculation remains accurate, but electricity consumption increases significantly
Solution Approach 1:
The rotational quantity detection unit dynamically changes its operational state based on power supply conditions. When the main power supply is turned off, the unit enters a sleep state where it does not continuously detect rotational quantity, thereby reducing electricity consumption. The unit transitions to a wake-up state when the counter electromotive voltage indicates steering wheel operation, allowing accurate detection only when necessary.
Solution Approach 2:
The system changes the operational parameter of the rotational quantity detection unit from continuous operation to intermittent operation based on the power supply state. By monitoring the counter electromotive voltage as a trigger parameter, the system activates detection only when the steering wheel is being operated, optimizing the balance between measurement accuracy and energy consumption.
2Use of energy by moving object
If the rotational quantity detection unit enters sleep state when main power supply is off, then electricity consumption is reduced, but detection accuracy may be compromised
Solution Approach 1:
The system uses feedback from the counter electromotive voltage detection to determine when to activate the rotational quantity detection unit. The counter electromotive voltage serves as a feedback signal indicating steering wheel operation, triggering the detection unit to wake up and perform accurate detection only when steering input is detected, thus maintaining measurement precision while minimizing energy consumption.
Solution Approach 2:
The rotational quantity detection unit serves itself by autonomously transitioning between sleep and wake-up states based on the counter electromotive voltage condition. This self-service mechanism eliminates the need for continuous external control signals, allowing the system to maintain detection accuracy automatically when steering operation occurs while consuming minimal power during standby periods.
3Use of energy by moving object
If the counter electromotive voltage is used to trigger detection, then unnecessary power consumption is eliminated, but the system complexity increases
Solution Approach 1:
The counter electromotive voltage detection mechanism serves multiple functions: it monitors steering wheel operation status and simultaneously acts as a trigger signal for activating the rotational quantity detection unit. This multi-functionality approach uses an existing electrical phenomenon (counter electromotive voltage) for dual purposes, reducing the need for additional sensors or complex control circuits while achieving both power savings and accurate detection triggering.
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 significantly reduces electricity consumption during standby mode and prevents errors in calculating the absolute steering angle by ensuring detection occurs only when the steering wheel is in use, thus conserving battery life and improving accuracy.
Implementation Method 1
a counter electromotive voltage detection unit for detecting a counter electromotive voltage of the electric motor
Data Source
AI summary
An electric power steering apparatus includes an electric motor configured to apply an assist torque to an steering system of a motor vehicle, a rotational quantity detection unit for detecting a rotational quantity of the electric motor while the rotational quantity detection unit is in a wake-up state, and a counter electromotive voltage detection unit for detecting a counter electromotive voltage of the electric motor. When a main power supply of the electric power steering apparatus is turned off, the rotational quantity detection unit enters into a sleep state, and when a prescribed condition is established based on the counter electromotive voltage detected by the counter electromotive voltage detection unit, the rotational quantity detection unit transitions from the sleep state to the wakeup state.