Bootstrap Gate Driving Circuit for Stable Floating Voltage
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Solution Overview
Problem
Switch elements connected to a floating voltage experience unstable driving voltages, affecting their switching performance and reliability due to fluctuations in supply voltage.
Innovation Solution
A driving circuit with a switching circuit, unidirectional switches, and capacitors stabilizes the voltage at the control terminal of switch elements by managing the charging and discharging process to maintain a stable threshold voltage, ensuring reliable operation even with floating voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the second power terminal is connected to a floating voltage, then the driving circuit can operate with flexible voltage levels, but the driving voltage becomes unstable due to floating voltage fluctuations
Solution Approach 1:
The patent introduces a bootstrap capacitor as an intermediary energy storage element between the floating voltage source and the switch element. This capacitor mediates the voltage transmission by storing energy during one switching cycle and releasing it during the next cycle, thereby isolating the switch element from direct exposure to floating voltage fluctuations and providing stable driving voltage.
Solution Approach 2:
The bootstrap capacitor is charged in advance during the off-state of the switch element, storing the necessary energy before the switch element needs to be activated. This preliminary energy storage ensures that when the switch element requires driving voltage, the capacitor can immediately provide stable voltage without being directly affected by floating voltage variations.
2Stability of the object's composition
If the supply voltage is stable, then the driving circuit can maintain consistent power delivery, but the driving voltage becomes unstable when the second power terminal is connected to floating voltage
Solution Approach 1:
The bootstrap capacitor serves as a voltage buffer and intermediary, decoupling the stable supply voltage from the floating voltage at the second power terminal. By charging from the stable supply and discharging to the switch element, the capacitor translates stable supply voltage into stable driving voltage despite floating terminal conditions.
Solution Approach 2:
The bootstrap capacitor provides beforehand cushioning by pre-storing energy in its electric field during periods when the switch is off. This stored energy acts as a voltage cushion that protects the switch element from voltage instability caused by floating terminal connections, ensuring continuous stable operation.
3Device complexity
If conventional driving circuits are used with floating voltage, then the circuit structure remains simple, but the switching performance and reliability of the switch element are reduced
Solution Approach 1:
The bootstrap capacitor is introduced as a minimal intermediary component that adds only one element to the conventional circuit structure. This simple addition provides substantial improvement in switching performance and reliability by stabilizing the driving voltage without significantly increasing circuit complexity.
Solution Approach 2:
The invention changes the voltage parameter stability through the bootstrap capacitor's energy storage and release mechanism. By controlling the capacitor's charging and discharging cycles, the circuit transforms unstable floating voltage conditions into stable driving voltage conditions, thereby improving switching performance with minimal structural modification.
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
The proposed driving circuit enhances the switching performance and reliability of switch elements by maintaining stable voltage levels, reducing fluctuations to less than ±5% of the average value, thereby improving operational stability.
Implementation Method 1
The first capacitor has a capacitance value, and the first capacitor has a charge during a charging-discharging process
Implementation Method 2
The first unidirectional switch includes a first terminal and a second terminal
Data Source
AI summary
A driving circuit for driving a switch element, which includes a control terminal, a first power terminal and a second power terminal. The second power terminal receives a first voltage. The driving circuit includes a switching circuit, a first unidirectional switch and a first capacitor. The switching circuit receives a first signal. The switching circuit is electrically connected with a first voltage terminal and a ground terminal. The first voltage terminal receives a second voltage. A voltage at the output terminal is switched between the second voltage and a ground voltage. A first terminal of the first unidirectional switch receives a third voltage. A first terminal of the first capacitor is connected with the output terminal of the switching circuit. A second terminal of the first capacitor is connected with a second terminal of the first unidirectional switch and the control terminal of the first switch element.