DC to DC Converter Smooth BUCK BOOST Mode Transition
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Solution Overview
Problem
DC to DC converters face challenges in smoothly transitioning between BUCK and BOOST modes, especially when the difference between input and output voltages becomes small, leading to discontinuities and glitches in operation.
Innovation Solution
A DC to DC converter design incorporating an inductor, electronically controllable switches, and a controller that maintains the order of switch operation irrespective of voltage stepping up or down, with additional transition regime detection to ensure a minimum current ripple and monotonic progression of switching times, allowing for smooth transitions between BUCK and BOOST modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the converter operates in conventional BUCK or BOOST mode separately, then the voltage conversion efficiency is high in each mode, but the transition between modes causes discontinuities and glitches when input voltage approaches output voltage
Solution Approach 1:
The converter uses a single unified circuit topology that can operate in both BUCK and BOOST modes without requiring separate circuit designs. The same inductor, switches, and rectifiers serve dual purposes depending on the switching sequence, eliminating mode-specific circuit variations and enabling smooth transitions.
Solution Approach 2:
The controller dynamically adjusts the switching sequence of the first and second switches based on the operating mode. By maintaining a consistent switching order (first switch then second switch) while adjusting duty cycles, the system adapts smoothly between BUCK and BOOST modes without discontinuities, even when input voltage approaches output voltage.
2Loss of energy
If the switching sequence is changed between BUCK and BOOST modes, then the voltage conversion is efficient, but discontinuities occur around Vin=Vout causing glitches
Solution Approach 1:
The controller maintains continuous and smooth switching action by preserving the same switching sequence (first switch closed, then second switch closed) across both BUCK and BOOST modes. This continuous approach prevents gaps or discontinuities in the control signal when transitioning around Vin=Vout, eliminating output voltage glitches.
Solution Approach 2:
The system changes operating parameters (duty cycles of switches) while maintaining the same switching sequence. By adjusting the on-times of the first and second switches rather than changing the switching order, the converter efficiently transitions between modes without causing discontinuities or energy losses.
3Ease of operation
If the converter maintains monotonic progression of switching times, then smooth transitions are achieved, but the control system complexity increases due to transition regime detection
Solution Approach 1:
The controller incorporates transition regime detection that monitors the relationship between input and output voltages. When the difference |Vout-Vin| falls below a threshold, the system detects the transition regime and adjusts switching times monotonically to maintain smooth transitions, using feedback to prevent discontinuities.
Solution Approach 2:
The controller proactively adjusts switching times before mode transitions occur by detecting when |Vout-Vin| becomes sufficiently small. This preliminary detection allows the system to prepare monotonic switching time progression in advance, ensuring smooth transitions without sudden jumps or glitches when Vin approaches Vout.
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
Enables seamless transitions between BUCK and BOOST modes without discontinuities, ensuring well-regulated output voltage even when the input voltage spans a range including the output voltage, thereby avoiding glitches and maintaining efficient operation.
Implementation Method 1
an inductor, first and second electronically controllable switches and a controller
Implementation Method 2
first electronically controllable switch is interposed between an input node and a first terminal of the inductor and the second electronically controllable switch extends between a second terminal of the inductor and a ground
Data Source
AI summary
A DC to DC converter comprising an inductor, first and second electronically controllable switches and a controller, wherein the first electronically controlled switch is interposed between an input node and a first terminal of the inductor and the second electronically controllable switch extends between a second terminal of the inductor and the ground and where a first rectifier extends between the ground and the first terminal of the inductor and a second rectifier connects the second terminal of the inductor to an output node, wherein the controller controls the operation of the first and second switches to perform voltage step down or voltage step up, as appropriate, to achieve a desired output voltage; and wherein the controller is arranged such that the order in which the first and second switches are operated is maintained irrespective of whether the converter is stepping up the input voltage or stepping down the input voltage.