Vehicle Power Supply Circuit for Battery Disconnect Voltage Hold
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Solution Overview
Problem
Conventional vehicle power supply systems experience unsaturated operation of semiconductor elements due to the rapid drop in power supply voltage when the battery is disconnected, leading to inefficient energy management and potential damage to the ACG drive circuit.
Innovation Solution
A vehicle power supply control circuit with a switch circuit and controller that regulates the conduction and interruption between the DC-DC converter output and the semiconductor elements, ensuring the power supply voltage remains within specific threshold levels to prevent unsaturated operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the power supply voltage is cut off quickly when the battery is disconnected, then the system stops faster and response time is improved, but the semiconductor elements operate in the unsaturated region causing energy loss and potential damage
Solution Approach 1:
The control circuit detects the battery disconnection state in advance and preliminarily controls the switch circuit to maintain power supply to the semiconductor elements before the voltage drops to the unsaturated region, preventing harmful operation before it occurs
Solution Approach 2:
A control circuit acts as an intermediary between the battery and semiconductor elements, monitoring voltage levels and mediating the power supply to ensure semiconductor elements receive adequate voltage even when the battery is disconnected, preventing unsaturated operation
2Reliability
If the output voltage of the DC-DC converter is held for some time after power supply cutoff, then the semiconductor elements are protected from unsaturated operation, but the power supply voltage drops faster when the battery is open
Solution Approach 1:
The control circuit dynamically adjusts the switch circuit state based on real-time voltage detection, transitioning from maintaining voltage when needed to allowing voltage drop when the battery is open, optimizing the balance between protection and energy retention
Solution Approach 2:
The control circuit continuously detects the power supply voltage and provides feedback to control the switch circuit, adjusting the output voltage holding based on the detected voltage level and battery status to prevent both unsaturated operation and unnecessary energy loss
3Reliability
If a switch circuit is introduced to control the conduction between DC-DC converter output and semiconductor elements, then unsaturated operation is prevented, but the device complexity increases
Solution Approach 1:
The control circuit performs multiple functions including voltage detection, switch control, and protection logic within a single integrated unit, reducing the need for separate components and minimizing overall circuit complexity while maintaining reliability
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 unsaturated operation of semiconductor elements by controlling the switch circuit based on power supply voltage thresholds, maintaining efficient energy management and extending the output voltage hold time after main switch cutoff.
Implementation Method 1
a voltage output from an DC-DC converter configured to convert a power supply voltage
Implementation Method 2
a switch circuit having one end connected to the first input terminal and another end connected to the output terminal, the switch circuit is configured to turn on based on a signal applied to a control terminal thereof to establish electrical connection between the first input terminal and the output terminal
Data Source
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AI summary
A power supply control circuit for a vehicle includes: a first input terminal to which a voltage output from an DC-DC converter converting a power supply voltage is supplied; a second input terminal to which the power supply voltage is supplied; an output terminal to output a voltage for controlling semiconductor elements that generate a drive current for a motor generator and have unsaturated region characteristics; a switch circuit having one end connected to the first input terminal and the other end connected to the output terminal, the switch circuit is turned on based on a signal applied to the control terminal to establish electrical connection between the first input terminal and the output terminal, on the other hand, the switch circuit is turned off based on a signal applied to the control terminal to cuts off between the first input terminal and the output terminal; and a switch controller that controls the switch circuit by applying a signal to the control terminal based on the voltage of the second input terminal.