Mixed Power Converter with Shared Oscillator Clock
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Solution Overview
Problem
Conventional buck converters face efficiency issues due to high voltage stress and require additional oscillators, increasing size, and experience transient current spikes when switched during inductor current decrease, impacting efficiency.
Innovation Solution
A mixed power converter with a switched-capacitor conversion circuit and an inductor buck circuit, where the switched-capacitor circuit operates without a dedicated clock generator, using a clock signal generated from the inductor buck circuit's switching signal to control switching timing, eliminating the need for extra oscillators and reducing transient current spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional buck converter is operated with a higher voltage conversion rate, then the voltage conversion capability is improved, but the voltage stress between input and output terminals increases, making it difficult to implement high efficiency
Solution Approach 1:
The power conversion process is divided into two stages: a switched-capacitor conversion circuit for initial voltage conversion and an inductor buck circuit for final voltage regulation. This segmentation allows each stage to operate optimally, with the switched-capacitor stage handling the bulk voltage conversion and the buck stage providing fine-tuned regulation, thereby maintaining high efficiency even at higher voltage conversion rates
Solution Approach 2:
The patent dynamically adjusts the switching frequency of the switched-capacitor circuit based on the operating conditions and the voltage conversion ratio. By making the switching frequency adaptive rather than fixed, the system can optimize its efficiency across different operating points, preventing excessive voltage stress and energy loss
2Loss of energy
If a mixed switched capacitor converter is used to achieve higher efficiency with higher voltage drop, then conversion efficiency is improved, but each converter stage needs a dedicated oscillator, increasing the size of the converter
Solution Approach 1:
The patent merges the clock generation function into the inductor buck circuit by using the buck circuit's existing oscillator to generate the clock signal for the switched-capacitor stage. This eliminates the need for a separate dedicated oscillator in the switched-capacitor stage, reducing overall device complexity and size while maintaining the efficiency benefits of the mixed converter architecture
Solution Approach 2:
The oscillator in the inductor buck circuit serves dual purposes: it generates the switching signal for the buck circuit itself and simultaneously provides the clock signal for the switched-capacitor conversion circuit. This multi-functionality reduces the total number of oscillators needed, thereby decreasing converter size without compromising efficiency
3Productivity
If the switched capacitor converter is switched during a period in which inductor current of the buck converter decreases, then the switching operation can proceed, but it causes a high transient current spike, impacting efficiency
Solution Approach 1:
The patent implements feedback control by monitoring the switching state of the buck circuit and using this information to control the switching timing of the switched-capacitor circuit. The buck circuit's switching signal serves as a reference that synchronizes the switched-capacitor stage, ensuring that its switching operations do not occur during periods when inductor current is decreasing, thereby preventing transient current spikes and maintaining efficiency
Solution Approach 2:
The system performs preliminary synchronization by using the buck circuit's switching signal to pre-coordinate the switched-capacitor circuit's operation. This ensures that the switched-capacitor stage is already aligned with the buck stage's current state before switching occurs, preventing harmful transient current spikes by avoiding switching during inductor current decrease periods
Data Source
AI summary
A power converter is provided. The power converter includes a switched-capacitor conversion circuit and an inductor buck circuit. The switched-capacitor conversion circuit receives an input voltage and operates according to a first operation frequency to convert the input voltage to an intermediate voltage. The inductor buck circuit is coupled to the switched-capacitor conversion circuit in series. The inductor buck circuit receives the intermediate voltage and operates on a second operation frequency to generate an output voltage at a conversion output terminal according to the intermediate voltage. The first operation frequency is determined according to the second operation frequency.