Bootstrap Capacitor Charging Circuit With Self-Timed Diode Bypass
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Solution Overview
Problem
Existing power converter designs face challenges in efficiently charging bootstrap capacitors, particularly in multi-level converters, due to the accumulation of diode forward-bias voltage drops, which reduces the available charging voltage and increases switching delays and power losses.
Innovation Solution
The implementation of self-timed supplemental circuit blocks, including trigger, trigger-bypass, and bypass blocks, which allow for the bypassing of diodes in the diode stack, enabling efficient charging of bootstrap capacitors without external control signals or synchronous logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diodes are used in the diode stack to charge bootstrap capacitors, then the charging path is simple and reliable, but the accumulated diode forward-bias voltage drops reduce the available charging voltage and increase power losses
Solution Approach 1:
The patent extracts and removes the diodes from the charging path by introducing supplemental circuit blocks that bypass the diode stack. The bypass blocks contain switches that can operate in parallel with the diodes, effectively taking out the diodes from the critical charging path to eliminate their forward-bias voltage drops while maintaining the charging function through alternative paths.
Solution Approach 2:
The patent introduces supplemental circuit blocks as intermediary elements between the voltage source and the bootstrap capacitors. These blocks contain switches and control logic that mediate the charging process, allowing controlled bypassing of the diode stack and enabling efficient charge transfer without the voltage drops inherent in diode-based paths.
2Device complexity
If diodes are used in the diode stack to charge bootstrap capacitors, then the circuit structure is simple, but the accumulated diode forward-bias voltage drops increase switching delays
Solution Approach 1:
The patent removes the diodes from the charging path by introducing supplemental circuit blocks with switches that can bypass the diode stack. This extraction eliminates the voltage drops that cause switching delays while the control logic ensures the bypass switches are activated at the appropriate times to maintain simple and efficient operation.
Solution Approach 2:
The patent introduces dynamic switching control through supplemental circuit blocks that can adaptively bypass the diode stack based on operational conditions. The switches are controlled to be conductive during charging phases and non-conductive during other phases, creating a dynamic system that optimizes charging speed and reduces switching delays while maintaining circuit simplicity.
3Measurement precision
If external control signals or synchronous logic are used to control the charging circuit, then the charging timing can be precisely controlled, but the device complexity increases
Solution Approach 1:
The patent implements self-service through supplemental circuit blocks that automatically control the charging process without requiring external control signals or synchronous logic. The blocks use local control logic and sensed voltage conditions to autonomously determine when to activate bypass switches, achieving precise charging timing control through self-regulation and eliminating the need for complex external control circuits.
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 solution effectively addresses the voltage drop issues in multi-level converters, ensuring that bootstrap capacitors are charged efficiently, reducing switching delays, and improving the overall efficiency and power density of the power converter.
Implementation Method 1
the accumulation of diode forward-bias voltage drops, which reduces the available charging voltage and increases switching delays and power losses
Data Source
AI summary
Power converter circuits and methods that include self-timed bootstrap capacitor power sources. Added to a power converter having a diode stack for charging bootstrap capacitors are three types of supplemental circuit blocks: a trigger block, a trigger-bypass block, and a bypass block. In operation, adjacent supplemental circuit blocks work in pairs. The upper block of the pair functions, when triggered, to charge an associated bootstrap capacitor by connecting the top plate of its associated bootstrap capacitor to the top plate of the bootstrap capacitor associated with the lower block of the pair, essentially bypassing the diode associated with the upper block. In addition, the lower block of the pair functions to initiate (trigger) the bypass function of the upper block. The bypass function of the upper block automatically terminates when the connected bootstrap capacitors are disconnected and their respective voltages “fly” apart, or is controllably terminated.