AHB Power Supply Control for ZVS and Skip-Mode Switching
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Solution Overview
Problem
Asymmetric half-bridge (AHB) power supplies face challenges in maintaining zero voltage switching (ZVS) for switches under medium or light loads, leading to increased switching loss and efficiency issues.
Innovation Solution
A control method for AHB power supplies that introduces a mixed operation mode, alternating between switching operation periods and skip periods. This method uses a compensation signal and its stable low-frequency component to determine when to end and start these periods, ensuring timely adjustments based on load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching cycle is increased to reduce switching frequency under medium or light load, then switching loss is reduced, but maintaining zero voltage switching (ZVS) for the switches becomes difficult
Solution Approach 1:
The patent implements dynamic switching between two operating modes (first operating mode with complementary switches for ZVS, and second operating mode with extended switching cycle for reduced switching loss) based on real-time detection of ZVS conditions. This dynamic adaptation allows the system to maintain optimal performance across varying load conditions by switching modes rather than relying on a single fixed configuration.
Solution Approach 2:
The system incorporates feedback mechanisms that detect whether ZVS is being maintained and use this information to control the operating mode. The detection of ZVS conditions provides feedback that triggers mode switching, ensuring that the system automatically adjusts its operation to maintain either ZVS or reduced switching loss depending on the current state.
2Speed
If the switching cycle is extended under light load, then switching frequency is reduced, but the ability to maintain ZVS deteriorates
Solution Approach 1:
The system dynamically adjusts switching frequency by alternating between two operating modes. In the first mode, switches operate complementarily with higher frequency to maintain ZVS. In the second mode, the switching cycle is extended to reduce frequency and switching loss. The system transitions between these modes based on detected ZVS conditions, providing dynamic frequency adaptation.
Solution Approach 2:
The patent changes the switching cycle parameter between two distinct values: a shorter cycle in the first operating mode to maintain ZVS, and a longer cycle in the second operating mode to reduce switching loss. This parameter change is controlled based on detected ZVS conditions, allowing the system to optimize between frequency and efficiency.
3Loss of energy
If switches operate in complementary mode to achieve ZVS, then switching loss is reduced, but switching frequency remains high under medium or light load
Solution Approach 1:
The system dynamically switches between two operating modes to balance switching loss and frequency. In the first mode, complementary switching maintains ZVS and reduces loss but operates at higher frequency. In the second mode, the switching cycle is extended to reduce frequency while accepting higher loss during the extended period. This dynamic mode switching allows the system to alternate between these trade-offs.
Solution Approach 2:
The patent implements periodic alternation between two operating modes. The system switches between the complementary switching mode (first operating mode) and the extended cycle mode (second operating mode) in a periodic fashion, allowing it to cycle between maintaining ZVS and reducing switching frequency, thereby achieving periodic optimization of both parameters.
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 proposed solution effectively reduces output voltage ripple and smooths voltage changes when load conditions shift, thereby minimizing damage to the load and improving overall power supply efficiency.
Implementation Method 1
The resonance circuit undergoes charging and discharging and resonates, allowing the switches to achieve zero voltage switching (ZVS) with low switching loss
Data Source
AI summary
A switch-mode power supply is used to provide an output voltage and includes an inductor and a power switch, where the power switch is used to control the current flowing through the inductor. A control method for the switch-mode power supply includes: providing a compensation signal controlled by the output voltage; providing a stable compensation signal for the low-frequency component of the compensation signal based on the compensation signal; providing a mixed operation mode, in which the switch-mode power supply alternately operates during a switching operation period and an skip period, the power switch opens at least once during the switching operation period, and the power switch is closed during the skip period; based on the difference between the compensation signal and the stable compensation signal, ending one of the switching operation period and skip period, and starting another one of the switching operation period and skip period.