Interleaved Flying Capacitor Converter Phase Shifts for Ripple Suppression
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Solution Overview
Problem
Existing interleaved power converters using phase-shift pulse width modulation (PSPWM) in flying capacitor multi-level circuits fail to effectively interleave the peaks and valleys of inductor currents, leading to inadequate reduction of the total input current ripple.
Innovation Solution
An interleaved flying capacitor multi-level converter with a phase-shifted pulse width modulation signal generation circuit that generates switch control signals with specific phase angle differences between upper and lower arm switches, ensuring that the peaks and valleys of input currents across bridge arms are interleaved to achieve ripple suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase-shift pulse width modulation (PSPWM) is used to control switches in flying capacitor multi-level circuits with 180-degree phase difference, then the control structure is simplified, but the peaks and valleys of inductor currents are not effectively interleaved, resulting in inadequate reduction of total input current ripple
Solution Approach 1:
The patent changes the phase angle parameter from the conventional 180 degrees to specific values (60, 120, 240, or 300 degrees) to achieve effective current interleaving. This parameter modification allows the peaks and valleys of inductor currents from different bridge arms to align properly, thereby reducing the total input current ripple while maintaining the PSPWM control structure
Solution Approach 2:
The patent introduces dynamic phase shift adjustment where the phase difference between control signals of switches in different bridge arms is dynamically set to specific values based on the number of levels. This dynamic adjustment enables the system to adaptively interleave current waveforms across different operating conditions, effectively reducing current ripple without complicating the control structure
2Power
If the number of bridge arms and switches is increased to handle high-power applications, then the power handling capability is improved, but the complexity of the circuit structure increases
Solution Approach 1:
The patent divides the high-power converter into multiple bridge arms, each handling a portion of the total power. By segmenting the circuit into modular bridge arms with standardized structures, the system achieves high power handling capability while keeping each module relatively simple and manageable
Solution Approach 2:
The patent designs each bridge arm with a universal flying capacitor multi-level structure that can handle multiple functions: power conversion, voltage multiplication, and current interleaving. This multi-functionality reduces the need for additional specialized components, thereby managing circuit complexity while maintaining high power capability
3Adaptability or versatility
If conventional 180-degree interleaved control is applied to flying capacitor multi-level circuits, then the control method is compatible with traditional interleaved converters, but the current ripple reduction effect is insufficient
Solution Approach 1:
The patent modifies the phase angle parameter from the standard 180 degrees to level-dependent specific values (60, 120, 240, or 300 degrees) while maintaining the overall PSPWM control framework. This parameter adaptation allows the control method to remain compatible with traditional interleaved converters structurally, while achieving superior current ripple reduction through optimized phase relationships
Data Source
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AI summary
An interleaved flying capacitor multi-level converter (600, 700) includes a plurality of arms and a phase-shift PWM generation circuit (610). Each arm includes a flying capacitor multi-level circuit having an upper arm and a lower arm coupled at a middle node (N1...Nm). The upper arm includes a plurality of serially coupled upper arm switches (S1A_1-SnA_1...S1A_m-SnA_m) and the lower arm includes a plurality of serially coupled lower arm switches (S1B_1SnB_1...S1B_m-SnB_m). One capacitor (C1_1-C(n-1)_1...C1_m-C(n-1)_m) is correspondingly coupled between every two upper arm switches (S1A_1-SnA_1...S1A_m-SnA_m) and every two lower arm switches (S1B_1-SnB_1...S1Bm-SnB_m). The phase-shift PWM generation circuit (610) generates a plurality of switch control signals (S1A_1-SnA_1...S1A_m-SnA_m, S1B_1-SnB_1...S1B_m-SnB_m) to respectively control the plurality of upper arm switches (S1A_1-SnA_1...S1A_m-SnA_m) and the plurality of lower arm switches (S1B_1-SnB_1...S1Bm-SnB_m).