Electric Power Steering Voltage Sub-Range Control
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Solution Overview
Problem
Existing electric power steering apparatuses face issues with battery voltage fluctuations, leading to unnecessary power consumption and potential obstruction of engine start due to the design of step-up circuits that operate at minimum voltages lower than predicted, causing instability in motor current supply and increased power consumption.
Innovation Solution
An electric power steering apparatus with a control unit and multiple power supply circuits that divide the input voltage range into three sub-ranges, allowing for controlled stoppage of power supply functions when the voltage falls within specific ranges, thereby preventing unnecessary power consumption and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the minimum operating voltage of the step-up circuit is set lower than the predicted decreased battery voltage to ensure normal operation during engine start, then the arithmetic circuit can operate without reset, but unnecessary power consumption increases and may obstruct engine start
Solution Approach 1:
The patent changes the operating parameters of the step-up circuit by dynamically adjusting its minimum operating voltage threshold based on battery voltage conditions. When battery voltage is above a predetermined threshold, the step-up circuit is inhibited from operating, thereby reducing unnecessary power consumption while maintaining arithmetic circuit reliability when needed
Solution Approach 2:
The patent introduces dynamic control of the step-up circuit operation based on real-time battery voltage monitoring. The control unit dynamically enables or disables the step-up circuit depending on whether battery voltage falls below the predetermined threshold, optimizing the balance between reliability and power consumption
2Reliability
If the step-up circuit operates at minimum voltage lower than predicted battery voltage, then voltage stability is maintained, but current supply to motor becomes unstable
Solution Approach 1:
The patent changes the voltage threshold parameter for step-up circuit operation from a fixed low value to a dynamic threshold based on predetermined battery voltage levels. This ensures that the step-up circuit only operates when genuinely needed, maintaining voltage stability for the arithmetic circuit while preventing current supply instability to the motor
3Duration of action of stationary object
If the battery voltage stays in the vicinity of the minimum operating voltage for a long period, then the arithmetic circuit continues to operate, but power consumption increases and engine start may be obstructed
Solution Approach 1:
The patent applies preliminary anti-action by setting a predetermined battery voltage threshold that prevents the step-up circuit from operating when battery voltage is sufficiently high. This preemptive measure avoids unnecessary power consumption and potential engine start obstruction before they can occur, while still ensuring arithmetic circuit operation when voltage actually drops
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 effectively reduces power consumption and maintains stable operation by controlling power supply functions based on voltage sub-ranges, preventing unnecessary power usage and ensuring the electric power steering apparatus functions efficiently even during battery voltage fluctuations.
Implementation Method 1
a power supply control circuit configured to output a stop signal for individually stopping output functions of the plurality of power supply circuits based on a result of reading an input voltage supplied in common to the plurality of power supply circuits
Data Source
AI summary
A plurality of power supply circuits include a second power supply circuit for a CPU included in a control unit and a first power supply circuit for another circuit. An output voltage from the first power supply circuit is higher than an output voltage from the second power supply circuit. A range of input voltage is divided into three levels of voltage sub-ranges in accordance with a requirements specification. When the input voltage falls within a lower level voltage sub-range, both of an output function of the first power supply circuit and an output function of the second power supply circuit are stopped. When the input voltage falls within an intermediate level voltage sub-range, the output function of the first power supply circuit is stopped. When the input voltage falls within an upper level voltage sub-range, all circuits are controlled so as to operate.