Vehicle Control Unit Power Path Switching for Low Quiescent Current
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Solution Overview
Problem
Existing motor vehicle control devices struggle to reduce quiescent current consumption when ignition is switched off, as they cannot temporarily disconnect components like steering systems from the vehicle electrical system without complete disconnection.
Innovation Solution
A motor vehicle control unit with an electronic switching element in the supply voltage path, controlled by a unit that switches the consumer on and off based on input signals, such as the ignition status, using a resistor and current control to manage voltage differences independently of the vehicle electrical system voltage, ensuring consistent switching without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If control units are completely disconnected from the vehicle electrical system to reduce quiescent current consumption, then energy savings are achieved, but control functions must be permanently available even when ignition is off
Solution Approach 1:
The patent divides the control unit into two distinct supply voltage paths: a first supply voltage path that can be switched off to reduce quiescent current consumption, and a second supply voltage path that remains permanently connected to ensure control functions are available when ignition is off. This segmentation allows selective power management without compromising functional availability.
Solution Approach 2:
Different parts of the control unit receive different power supply configurations: some components are supplied through the switchable first path for energy savings, while critical components are supplied through the permanently connected second path for reliability. This local differentiation optimizes both energy efficiency and functional availability.
2Reliability
If voltage detection is used to switch between supply voltage paths, then undervoltage failures are detected, but switching errors may occur due to voltage fluctuations
Solution Approach 1:
The control unit continuously monitors the voltage level in the first supply voltage path and uses this feedback to automatically switch between the first and second supply voltage paths. When undervoltage is detected in the first path, the system switches to the second path, ensuring continuous operation without complex external control mechanisms.
3Loss of energy
If individual consumers are switched off to limit power consumption, then battery charge level is preserved, but switching devices add complexity to the electrical system
Solution Approach 1:
The patent combines multiple functions into the control unit itself: voltage detection, automatic switching control, and consumer management are all integrated within the control unit. This eliminates the need for separate external switching devices and voltage detection circuits, reducing overall system complexity while achieving power consumption limits.
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 solution allows for significant reduction in current consumption by temporarily disconnecting unnecessary consumers, maintaining functionality of essential components, and avoiding power loss due to undervoltages or overvoltages, while ensuring uninterrupted power to critical direct consumers.
Implementation Method 1
an electronic switching element (20) for arrangement in a supply voltage path (12.1) of the load (40) and a control unit (30) for controlling the electronic switching element (20)
Implementation Method 2
The control unit (30) has a current control (39) for generating a voltage difference across the resistor (36) as a control signal for the electronic switching element (20)
Data Source
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AI summary
The invention relates to a motor vehicle control device (9) for at least one electrical consumer (40) that is to be controlled, comprising an electronic switching element (20) for arrangement in a supply voltage path (12.1) of the consumer (40) and a control unit (30) for controlling the electronic switching element (20), wherein the control unit (30) is designed to provide a control signal for switching the electronic switching element (20) as a function of at least one input signal (38).