Auxiliary Power Supply Device for Electric Power Steering
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Solution Overview
Problem
In electric power steering systems, regenerative currents generated during end abutment can accelerate the deterioration of lead batteries used as main power supplies, leading to discomfort for drivers and reduced product lifespan.
Innovation Solution
An auxiliary power supply device with a control unit that switches between a main power supply and an auxiliary power supply to prevent regenerative currents from flowing back to the main power supply, using a switching unit with diodes and changeover switching elements to direct currents to an inverter, thereby blocking regenerative currents from reaching the lead battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative current is allowed to flow to the main power supply during end abutment, then energy recovery is achieved, but the lead battery deteriorates faster
Solution Approach 1:
The patent introduces an auxiliary power supply as an intermediary component between the motor and the main power supply. When regenerative current is generated during end abutment, the auxiliary power supply receives this current instead of allowing it to flow directly to the main lead battery. This mediator approach protects the main power supply from harmful regenerative currents while still capturing and storing the regenerative energy for future use.
Solution Approach 2:
The power supply system is segmented into two separate components: a main power supply for normal operation and an auxiliary power supply specifically for handling regenerative energy. This segmentation allows each component to be optimized for its specific function, with the auxiliary power supply being better suited to handle the high-rate charging from regenerative braking without damaging the main lead battery.
2Reliability
If switching circuits are added to control current flow, then regenerative current protection is achieved, but device complexity increases
Solution Approach 1:
The control unit acts as an intelligent intermediary that automatically manages the switching circuits. It monitors system conditions and controls the switching elements to direct current flow appropriately, protecting the main power supply from regenerative currents without requiring complex manual intervention or overly complicated circuit design.
Solution Approach 2:
The switching circuits are designed to be dynamically controllable, allowing the system to adapt its configuration based on operating conditions. The switching elements can change their state (on/off) in response to real-time system needs, enabling flexible current path management that protects the main power supply while maintaining system efficiency.
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
Prevents regenerative currents from flowing to the main power supply, reducing battery deterioration and enhancing the longevity and reliability of the electric power steering system.
Implementation Method 1
the first switching circuit includes a first diode forming a parallel circuit together with a first changeover switching element and connected in a forward direction to the main power supply; the second switching circuit includes a second diode forming a parallel circuit together with a second changeover switching element and connected in a reverse direction to the auxiliary power supply
Data Source
AI summary
An auxiliary power supply device includes a parasitic diode forming a parallel circuit together with a second switching element and connected in a forward direction to a main power supply, and a parasitic diode forming a parallel circuit together with a fourth switching element and connected in a reverse direction to an auxiliary power supply. When a state parameter indicates that a reaction force that interferes with operation of an assist motor is applied, an electronic control unit turns ON a first switching element, turns OFF the second switching element, turns ON a third switching element, and turns OFF the fourth switching element. A regenerative current from the assist motor flows to the auxiliary power supply via an inverter, the third switching element, and the parasitic diode.