DC-DC Converter Current Trimming for Fine Output Resolution
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Solution Overview
Problem
Existing DC-DC power converters face inadequate output current resolution, particularly at small current levels, due to limitations in the time resolution of control pulses, leading to undesirable complexity and cost when using high-end control circuits.
Innovation Solution
Incorporating a controllable resistive path or controllable current source between terminals of the DC-DC power converter, controlled by a secondary signal to adjust the output current, allowing for higher resolution through multibit control signals, including transistors operating in linear or triode-mode, and using feedback loops for self-oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-end control circuits (microprocessor, FPGA) are used to improve time resolution of control pulses, then output current resolution is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary current source that operates in parallel with the main switched converter core. This current source is controlled by a separate control signal and provides fine-resolution current adjustment without requiring high-end control circuits for the main converter. The intermediary acts as a mediator that handles the high-precision current control task independently, allowing the main converter to use simpler control circuitry while still achieving high overall output current resolution.
2Device complexity
If standard PWM control is used for DC output current control, then device complexity is kept low, but output current resolution is insufficient at small current levels
Solution Approach 1:
The patent segments the output current control into two independent parts: a main current component controlled by PWM signals for coarse adjustment, and an additional current component from a separate current source for fine adjustment. This segmentation allows each control path to be optimized independently - the PWM path maintains simplicity while the additional current path provides high resolution, together achieving both low complexity and high precision.
3Loss of energy
If switching frequency is increased to improve conversion efficiency, then switching losses are reduced, but output current resolution deteriorates due to minimum pulse width limitations
Solution Approach 1:
The patent uses an intermediary current source that operates independently of the main switching frequency. This current source can provide continuous or finely stepped current adjustment without being constrained by the minimum pulse width of the high-frequency PWM signals. The intermediary mediates between the high-frequency switching operation (which minimizes losses) and the need for fine current resolution, allowing both objectives to be achieved simultaneously.
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
Enhances output current resolution by enabling fine adjustments of the load current, improving perceptual quality in LED lighting and other applications, while maintaining efficiency even at low current levels.
Implementation Method 1
The controllable resistive path or controllable current source, which is configured to add a secondary DC output current to the primary DC output current or subtract the secondary DC output current from the primary DC output current in response to a secondary, and separate, control signal
Implementation Method 2
including transistors operating in linear or triode-mode
Implementation Method 3
using feedback loops for self-oscillation
Implementation Method 4
relying on the resonances of circuit capacitances and inductances to shape the waveform of either the current or the voltage across the switching element(s)
Data Source
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AI summary
The present invention relates to a DC-DC power converter which comprises a switched converter core operated in accordance with a primary control signal to supply a primary DC output current (Io) of the converter; said primary control signal exhibiting a minimum resolution, e.g. a minimum time step, leading to a corresponding minimum current step of the primary DC output current. The DC-DC power converter additionally comprises a controllable resistive path, or a controllable current source, connected between a pair of terminals selected from a group of: (the positive output terminal, the negative output terminal, the positive input terminal, the negative input terminal) and configured to add or subtract a secondary DC output current (Icon) to the primary DC output current (Io) in accordance with a secondary control signal to adjust the load current.