Switching Mode Converter 100% Duty Cycle Bootstrap Control
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Solution Overview
Problem
Conventional switching mode converters face limitations in achieving 100% duty cycle mode and preventing excessive voltage application to switching elements, leading to operational issues and increased costs due to the need for external capacitors and high-power charge pumps.
Innovation Solution
A switching mode converter with a control unit that manages the output current and voltage of a common charge pump to control the charging of a bootstrap capacitor and gate voltage, allowing for safe implementation of 100% duty cycle mode without external capacitors and preventing excessive voltage application by detecting and discharging excessive gate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-power charge pump is used to provide complete high-side gate drive for 100% duty cycle, then the gate drive capability is improved, but the cost and device complexity increase significantly
Solution Approach 1:
The patent combines the charge pump circuit and bootstrap capacitor into a single integrated unit. The charge pump transfers charge to the bootstrap capacitor, which then provides the gate drive voltage. This merging eliminates the need for separate high-power charge pump components and external capacitors, reducing device complexity while maintaining 100% duty cycle capability.
Solution Approach 2:
The integrated circuit performs multiple functions: it acts as both a charge pump and a bootstrap capacitor, provides gate drive voltage, and includes overvoltage protection. This multi-functionality eliminates the need for separate dedicated components, reducing overall device complexity while maintaining reliability.
2Reliability
If a high-power charge pump is used to provide complete high-side gate drive, then the gate drive capability is improved, but additional external capacitors are required increasing cost
Solution Approach 1:
The charge pump and bootstrap capacitor are merged into a single integrated circuit block. This eliminates the need for separate external capacitor components, reducing component count and manufacturing cost while maintaining the ability to provide complete gate drive for 100% duty cycle operation.
Solution Approach 2:
The integrated circuit is self-sufficient, generating its own gate drive voltage through the internal charge pump and storing it in the integrated bootstrap capacitor. This self-service capability eliminates dependency on external components, reducing both cost and assembly complexity.
3Stability of the object's composition
If the duty cycle is increased to 100% to maintain output voltage when input voltage drops, then the output voltage stability is improved, but the bootstrap capacitor cannot be recharged
Solution Approach 1:
The charge pump transfers charge to the bootstrap capacitor in advance, during periods when the switching element is off. This preliminary charging ensures that sufficient voltage is stored before 100% duty cycle operation begins, allowing the capacitor to maintain gate drive voltage even when the switching element remains continuously on.
Solution Approach 2:
The charge pump operates continuously or periodically to maintain the bootstrap capacitor charge, ensuring uninterrupted gate drive voltage supply. This continuous charging action ensures that the bootstrap capacitor remains charged even during extended 100% duty cycle periods, maintaining output voltage stability.
4Reliability
If charges are transferred from the charge pump to the gate, then the gate drive voltage is improved, but excessive voltage may damage the switching element
Solution Approach 1:
The control unit monitors the voltage at the gate terminal and adjusts the charge pump operation accordingly. When the gate voltage approaches the maximum safe level, the control unit reduces or stops charge transfer. This feedback control prevents overcharging and protects the switching element from excessive voltage damage while maintaining adequate gate drive voltage.
Solution Approach 2:
The control unit proactively prevents excessive voltage by monitoring charge pump operation and interrupting charge transfer before dangerous voltage levels are reached. This preliminary protective action stops the charging process when predefined safety thresholds are approached, preventing potential damage before it occurs.
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 stable 100% duty cycle operation and prevents switching element damage by controlling the gate voltage, improving reliability and reducing costs by eliminating the need for additional capacitors and high-power components.
Implementation Method 1
charges transferred from a charge pump
Implementation Method 2
bootstrap capacitor
Data Source
AI summary
Disclosed herein are a switching mode converter and a method for controlling thereof. The switching mode converter includes a switching element, a bootstrap capacitor, and a control unit. The switching element is connected between one side of a first semiconductor device, another side of the first semiconductor device is connected to a ground, and an input power. The bootstrap capacitor is configured such that one side of the bootstrap capacitor is connected to the one side of the first semiconductor device. The control unit controls the output current or output voltage of a common charge pump provided to the switching element and the bootstrap capacitor in order to control the charging state of the bootstrap capacitor and the gate voltage of the switching element.