Buck Converter With Mutually Coupled Inductive Coils
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Solution Overview
Problem
Buck converters face a trade-off between fast load transient response and high efficiency, as small inductors provide faster response but compromise on efficiency, while large inductors enhance efficiency at the cost of slower response, particularly in pulsed frequency modulation (PFM) mode.
Innovation Solution
The use of mutually coupled inductive coils with adjustable coupling ratios, allowing the buck converter to switch between 'sleep' and 'sync' modes to optimize inductance for either high efficiency at low load currents or fast response at high load currents, utilizing weak coupling for faster response and strong coupling for higher efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If small inductors are used, then fast load transient response is achieved, but efficiency is compromised
Solution Approach 1:
The patent applies dynamics by making the inductance value variable rather than fixed. The inductor switches between two different inductance values (first inductance and second inductance) depending on the operating conditions. During load transient events, the circuit selects the smaller inductance value to enable faster current response. During steady-state low-load operation, it selects the larger inductance value to minimize ripple current and maximize efficiency. This dynamic adjustment resolves the contradiction between fast response and high efficiency.
Solution Approach 2:
The patent changes the inductance parameter based on operating conditions. A switch selectively connects the inductor to operate in either a first mode (with first inductance value for fast response) or a second mode (with second inductance value for high efficiency). The control circuit monitors load conditions and automatically adjusts the inductance parameter to match the required performance characteristics, thereby achieving both fast transient response and high efficiency at different operational stages.
2Loss of energy
If large inductors are used, then efficiency is enhanced, but load transient response becomes slower
Solution Approach 1:
The circuit dynamically adjusts the inductance value based on operational requirements. When high efficiency is the priority (steady-state low-load conditions), the larger inductance value is selected to reduce ripple current and energy losses. When fast response is needed (load transient conditions), the smaller inductance value is selected. This dynamic switching capability allows the system to optimize for efficiency when possible while maintaining the ability to respond quickly when necessary.
Solution Approach 2:
The inductance parameter is changed based on the operational mode. The control circuit detects load transient conditions and switches the inductor to a smaller inductance value to improve response speed. During normal steady-state operation, it switches to a larger inductance value to enhance efficiency. This parameter adjustment strategy resolves the contradiction by allowing the system to operate at the optimal point for each specific condition.
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 approach enables simultaneous optimization of both efficiency and load transient response, achieving higher efficiency at low output currents and faster response at high output currents, with the efficiency under 'sleep' mode being 1% higher and response under 'sync' mode being significantly faster.
Implementation Method 1
mutually coupled inductive coils with adjustable coupling ratios, allowing the buck converter to switch between 'sleep' and 'sync' modes to optimize inductance
Implementation Method 2
The buck converter storing the magnetic energy into the inductive coil charges inductor L 630
Data Source
AI summary
A variable efficiency and response buck converter is achieved. The device includes a multi-phase switch, the coupled coils, the filter capacitor, and the load. The multi-phase switch includes the phase control inputs, the circuit common reference, at least two pairs of complementary switches with each switch containing one upper switch and one lower switch, at least two phase control outputs from the complementary switches. The coupled inductive coils are coupled to the phase control outputs to enable weak couplings and strong couplings. Based on the working mode, equivalently the coupled coils can provide strong mutual inductances and weak mutual inductances. The filter capacitors connected to the output of the coupled coils provide high efficiency output to the load.