Multiphase Power Supply Circuit for Bootstrap Voltage Stability
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Solution Overview
Problem
The dynamic performance of multi-phase modulation power supply circuits is compromised due to unstable voltage differences between the terminals of the bootstrap capacitor, leading to voltage fluctuations and potential damage to switching transistors, despite attempts to alleviate these issues through increased capacitance, which only slow down the change in voltage differences without resolving the underlying instability.
Innovation Solution
The addition of a first and second switching transistor, along with a first and second capacitor, where the second capacitor's charge is balanced by the ideal charge storage capacity of the first capacitor, stabilizing the voltage difference between the terminals of the bootstrap capacitor, thereby preventing voltage deviations and providing a buffer function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the capacitance of the bootstrap capacitor is increased to reduce voltage fluctuations, then the stability of voltage difference is improved, but the response speed of the power supply circuit deteriorates
Solution Approach 1:
The patent divides the single bootstrap capacitor into two separate capacitors: a first capacitor connected to the high-side switching element and a second capacitor connected to the low-side switching element. This segmentation allows each capacitor to be optimized independently - the first capacitor can be smaller for faster response while the second capacitor compensates for voltage differences, thus resolving the contradiction between stability and response speed.
2Productivity
If the switching frequency is increased to improve tracking bandwidth, then the dynamic performance is improved, but switching losses increase and efficiency deteriorates
Solution Approach 1:
The patent employs periodic charging and discharging cycles of the two capacitors synchronized with the switching frequency. By optimizing the capacitance values and switching timing, the system achieves high tracking bandwidth through efficient periodic energy transfer while minimizing switching losses through zero-voltage switching techniques and optimized dead time.
3Reliability
If additional components are added to stabilize the voltage difference, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent implements a self-balancing mechanism where the two capacitors automatically equalize their voltage differences through controlled switching operations. The control circuit monitors the voltage across each capacitor and periodically transfers charge between them, eliminating the need for external voltage regulation components and reducing overall system complexity while improving reliability.
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 fundamentally stabilizes the voltage difference between the bootstrap capacitor terminals, enhancing the dynamic performance of the circuit system and preventing overheating and efficiency reduction, while maintaining a small number of additional elements and avoiding static power consumption.
Implementation Method 1
one terminal of the first capacitor is connected to one terminal of the second capacitor, the other terminal of the first capacitor is connected to each of a first electrode of the first switching transistor and a first electrode of the second switching transistor
Data Source
Figure 1
Figure 2~3
AI summary
Embodiments of this application provide a power supply circuit and an apparatus, including: the circuit includes a plurality of channels, and at least one channel of the plurality of channels includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, and a second capacitor, where one terminal of the first capacitor is connected to one terminal of the second capacitor, the other terminal of the first capacitor is separately connected to a first electrode of the first switching transistor and a first electrode of the second switching transistor, a second electrode of the first switching transistor is connected to a second electrode of the third switching transistor, a second electrode of the second switching transistor is connected to a second electrode of the fourth switching transistor, a third electrode of the first switching transistor is connected to an output node, and a third electrode of the second switching transistor is grounded. During implementation of this embodiment of this application, charging charges of the second capacitor are balanced by using an ideal charge storage capacity of the first capacitor. This improves stability of a circuit system and dynamic performance of the circuit system.