Bootstrap Capacitor Charging Route Switching for Stable Boot Voltage
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Solution Overview
Problem
Existing electromagnetic valve driving devices face challenges in stably generating a boot voltage for controlling high-side switching elements due to power loss when dropping boosted voltage, and instability in battery voltage during vehicle operation or abnormalities.
Innovation Solution
The electromagnetic valve driving device incorporates a boost circuit, multiple switching elements, and a bootstrap capacitor with dual charging routes from both the battery and boost circuit, allowing the switching control unit to switch between charging routes based on battery voltage levels to minimize power loss and ensure stable boot voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boosted voltage is dropped to generate charging voltage for the bootstrap capacitor, then the boot voltage can be generated, but large power loss occurs
Solution Approach 1:
The patent implements dynamic switching between two charging routes based on real-time battery voltage conditions. The switching element selectively connects the bootstrap capacitor to either the first charging route (from battery) or the second charging route (from boost circuit), optimizing power efficiency by avoiding unnecessary voltage dropping when battery voltage is sufficient.
Solution Approach 2:
The patent changes the operating parameters by introducing a voltage threshold comparison mechanism. When battery voltage exceeds a predetermined threshold, the system switches to the first charging route; otherwise, it uses the second charging route. This parameter-based switching resolves the contradiction by adapting to varying voltage conditions.
2Loss of energy
If the battery voltage is used to charge the bootstrap capacitor, then power loss is reduced, but the boot voltage may become unstable when battery voltage is low or unstable
Solution Approach 1:
The patent introduces a switching element as an intermediary that mediates between the battery, boost circuit, and bootstrap capacitor. This intermediary selectively routes charging current from the appropriate source based on voltage conditions, ensuring stable boot voltage generation while minimizing power loss by avoiding unnecessary energy conversion.
Solution Approach 2:
The system dynamically adapts the charging source based on real-time battery voltage monitoring. When battery voltage is sufficient (above threshold), the first charging route is activated; when battery voltage is low or unstable (below threshold), the system automatically switches to the second charging route from the boost circuit, maintaining boot voltage stability under varying conditions.
3Device complexity
If a single charging route from the battery is used, then the device complexity is reduced, but the system cannot handle low or unstable battery voltage conditions
Solution Approach 1:
The patent implements a multi-functional charging system where the bootstrap capacitor can be charged from two different sources (battery or boost circuit) depending on conditions. The switching element provides universal adaptability, allowing the system to handle both normal and abnormal voltage conditions, thereby improving reliability without excessive complexity increase.
Solution Approach 2:
The charging system is segmented into two distinct charging routes with a switching element that selects between them. The first charging route charges from the battery, while the second charging route charges from the boost circuit. This segmentation allows independent optimization of each route and reliable operation under different voltage conditions.
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 configuration enables stable generation of the boot voltage for high-side switching element control, reducing power loss and maintaining reliability even when battery voltage is low or unstable, thus ensuring efficient operation of the fuel injection valve.
Implementation Method 1
a boost circuit that boosts a battery voltage
Implementation Method 2
a bootstrap capacitor that generates a voltage necessary to turn the first switching element and the second switching element into an ON state
Data Source
AI summary
An electromagnetic valve driving device that drives an electromagnetic valve for injecting a fuel, includes: a first charging route that charges a bootstrap capacitor from a battery without intervention of a boost circuit; a second charging route that charges the bootstrap capacitor from the boost circuit; and a switching control unit that switches a charging route for charging the bootstrap capacitor to the first charging route or the second charging route.