Switched Capacitor Buck Converter With Adaptive BCM-DCM-CCM Control
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Solution Overview
Problem
Conventional three-level buck converters face inefficiencies due to fixed operating modes and require voltage balancing for flying capacitors, limiting their adaptability and efficiency in switching processes.
Innovation Solution
A switched capacitor voltage converter circuit that automatically switches between boundary conduction mode (BCM), discontinuous conduction mode (DCM), and continuous conduction mode (CCM) based on output current or switching frequency, using a control circuit to generate PWM signals and adjust switching signals for zero current or zero voltage switching, thereby optimizing efficiency and eliminating the need for voltage balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional three-level buck converter operates in a fixed mode, then the circuit structure is simple, but the efficiency and adaptability are limited
Solution Approach 1:
The patent implements dynamic mode switching between BCM, DCM, and CCM based on real-time output current detection. The control circuit automatically selects the optimal conduction mode according to load conditions, transforming the fixed-mode operation into a dynamic adaptive system that optimizes efficiency across different operating points
Solution Approach 2:
The patent employs feedback mechanisms through output current detection and comparison with reference thresholds. The control circuit receives feedback about the actual operating mode and adjusts switching signals accordingly, enabling closed-loop control that maintains optimal performance while adapting to changing load conditions
2Reliability
If voltage balancing is implemented for flying capacitors, then the converter operates reliably, but the device complexity and control overhead increase
Solution Approach 1:
The patent achieves voltage balancing through self-service mechanisms inherent in the switched capacitor topology and control method. By strategically controlling the switching sequences and utilizing the capacitor network configuration, the system automatically maintains voltage balance without requiring external balancing circuits or additional control overhead
Solution Approach 2:
The control circuit performs multiple functions simultaneously: it manages mode switching between BCM/DCM/CCM, controls the switching signals for power conversion, and maintains flying capacitor voltage balance. This multi-functionality is achieved through a unified control architecture that integrates these functions without requiring separate dedicated circuits for each task
3Loss of energy
If the converter operates in BCM or DCM, then the switching loss is reduced, but the output current capability is limited
Solution Approach 1:
The patent dynamically changes operating parameters including conduction mode (BCM/DCM/CCM), switching frequency, and duty cycle based on output current requirements. At light loads, the system operates in BCM or DCM with lower switching frequencies to minimize losses, while at heavy loads it transitions to CCM with adjusted parameters to maximize current capability, achieving optimal performance across the full operating range
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 solution enhances efficiency by adaptively adjusting switching frequencies and modes, reducing power loss during switching and outperforming prior art three-level buck converters in terms of efficiency and operational flexibility.
Implementation Method 1
an inductor, which is coupled between the output capacitor and the switching circuit
Implementation Method 2
a flying capacitor coupled to the switch circuit, wherein the flying capacitor and the output capacitor constitute a voltage divider
Data Source
AI summary
A switched capacitor voltage converter circuit for converting a first voltage to a second voltage includes: an output capacitor; a switched capacitor converter; and a control circuit. The switched capacitor converter includes: a switch circuit including fourth switches; an inductor coupled between the switch circuit and the output capacitor; and a flying capacitor coupled to the switch circuit, wherein the flying capacitor and the output capacitor constitute a voltage divider. The control circuit generates a PWM signal according to the second voltage and generates switch signals according to the PWM signal to control the switch circuit, so as to convert the first voltage to the second voltage. The control circuit decides whether the switched capacitor converter operates in a boundary conduction mode, a discontinuous conduction mode or a continuous conduction mode according to an output current or an output current related signal.