Vehicle Control Apparatus Power Boost-Startup Control
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Solution Overview
Problem
Hybrid vehicles face challenges in starting the engine when the high-voltage battery fails to supply sufficient power or when regenerative power generation is not possible, especially when the vehicle is stationary.
Innovation Solution
A vehicle control apparatus that includes a DC-DC converter, a capacitor, and a high-voltage battery determination portion, which executes power boost-startup control by boosting the output voltage of the accessory battery using the DC-DC converter to charge the capacitor, allowing the engine to be started using the electrical energy stored in the capacitor, even when the high-voltage battery is abnormal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started by using power generated from regenerative power generation, then the engine can be started without high-voltage battery power, but the engine cannot be started when the vehicle is at a standstill or when regenerative power generation fails
Solution Approach 1:
A capacitor is introduced as an intermediary energy storage device between the accessory battery and the starter. The capacitor temporarily stores electrical energy required for engine starting, enabling the starter to operate even when the high-voltage battery cannot supply sufficient power or when regenerative power generation is unavailable. This mediator allows energy transfer from the accessory battery through the capacitor to the starter, resolving the limitation of direct regenerative starting.
Solution Approach 2:
The system changes the voltage parameter by using a DC-DC converter to boost the output voltage of the accessory battery to a level suitable for charging the capacitor and operating the starter. This voltage transformation enables the low-voltage accessory battery to contribute energy for high-voltage starter operation, expanding the conditions under which engine starting can occur.
2Reliability
If the high-voltage battery maintains a high state of charge for engine startup, then reliable starting is ensured, but the usable range of the battery's state of charge increases
Solution Approach 1:
The energy storage function is segmented between multiple components: the high-voltage battery for general power supply, the capacitor for temporary starting energy storage, and the accessory battery as a backup power source. This segmentation allows the high-voltage battery to operate with a lower minimum state of charge since the capacitor and accessory battery provide backup starting capability, thereby reducing the usable range requirement while maintaining reliability.
3Device complexity
If the starter is driven directly by the accessory battery, then simple control is achieved, but voltage fluctuations adversely affect vehicle accessories
Solution Approach 1:
The capacitor serves as a buffer intermediary between the accessory battery and the starter. It absorbs voltage fluctuations and provides smooth energy delivery during starter operation, preventing adverse effects on vehicle accessories while enabling the accessory battery to power the starter. The capacitor's energy storage capability decouples the direct connection, isolating voltage disturbances.
4Speed
If the DC-DC converter provides instantaneous power for capacitor charging, then fast charging is achieved, but excessive power increase is required
Solution Approach 1:
The DC-DC converter charges the capacitor in advance before engine starting is required. By performing preliminary charging during periods when power demand is lower, the system avoids the need for high instantaneous power during critical starting moments. The capacitor is pre-filled with energy, ensuring rapid availability without demanding excessive peak power from the DC-DC converter.
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
Enables engine startup using the accessory battery's power, preventing voltage fluctuations and reducing the need for maintaining a high state of charge in the high-voltage battery, thus lowering the usable range of the battery's state of charge and minimizing power consumption.
Implementation Method 1
a DC-DC converter that is connected between the accessory battery and the high-voltage battery; a capacitor that is connected to a circuit on a side of the high-voltage battery; a startup control portion that executes power boost-startup control when the high-voltage battery determination portion determines that the high-voltage battery has an abnormality, the power boost-startup control boosting the output voltage of the accessory battery by the DC-DC converter, charging the capacitor with electrical energy required to start the engine by using power output from the DC-DC converter
Implementation Method 2
charging the capacitor with electrical energy required to start the engine by using power output from the DC-DC converter, and starting the engine by driving the starter with the electrical energy charged in the capacitor
Data Source
AI summary
A vehicle control apparatus comprises an engine, a starter, an accessory battery, and a high-voltage battery. The vehicle control apparatus is equipped with a DC-DC converter that is connected between the accessory battery and the high-voltage battery, a capacitor that is connected to a circuit on a side of the high-voltage battery, a high-voltage battery determination portion, and a startup control portion. The startup control portion executes power boost-startup control, whereby an output voltage of the accessory battery is boosted by the DC-DC converter, the capacitor is charged with necessary electrical energy for starting the engine by using an output voltage of the DC-DC converter, and the starter is driven to start the engine by using the electrical energy charged in the capacitor.