Isolated Converter Current Sensing Across a Wide Output Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing isolated converters face challenges in accurately sensing secondary side current over a wide current range due to optimization issues with auxiliary windings or current sense transformers, leading to decreased signal quality at lower currents or increased power losses at higher currents.
Innovation Solution
The solution involves an adjustable sensing circuit and control unit that dynamically optimizes the feedback signal ratio by altering characteristics such as auxiliary winding turns, shunt resistance, amplifier gain, and ADC reference voltage to adapt to different output currents, ensuring accurate current sensing across varying ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the auxiliary winding or current sense transformer is optimized for high output currents, then power losses at high currents are reduced, but signal quality at low output currents decreases
Solution Approach 1:
The patent applies dynamics by making the measurement path adjustable rather than fixed. The converter can dynamically switch between different measurement paths depending on the operating current level. At high currents, one measurement path is used to minimize power losses, while at low currents, a different path provides better signal quality. This dynamic adaptation resolves the contradiction between power efficiency and measurement precision across different operating conditions.
Solution Approach 2:
The patent changes the electrical parameters of the measurement path based on operating conditions. By adjusting parameters such as the number of winding turns in the auxiliary winding or the configuration of current sense transformers, the system optimizes the measurement path for the current operating level. This parameter adjustment allows the system to achieve both low power losses at high currents and high signal quality at low currents.
2Measurement precision
If the auxiliary winding or current sense transformer is optimized for low output currents, then signal quality at low currents is improved, but power losses at high currents increase
Solution Approach 1:
The system dynamically selects the appropriate measurement path based on the operating current. When low currents are detected, the system configures the measurement path to maximize signal quality. When high currents are detected, it switches to a configuration that minimizes power losses. This dynamic behavior eliminates the need to compromise between the two opposing requirements.
Solution Approach 2:
The patent employs parameter changes in the measurement path configuration. By adjusting electrical parameters such as winding turns ratios or sense resistor values based on the operating current level, the system achieves optimal performance at both low and high currents. This parameter adaptation allows the system to overcome the limitation of fixed-configuration designs.
3Device complexity
If a single measurement path is used for the entire current range, then device complexity is reduced, but measurement accuracy across the wide current range deteriorates
Solution Approach 1:
The patent segments the measurement function into multiple measurement paths, each optimized for specific current ranges. Rather than using a single general-purpose measurement path, the system divides the measurement task into specialized sub-paths. This segmentation allows each path to be optimized for its specific operating range, improving overall measurement accuracy across the wide current range while managing complexity through functional division.
Solution Approach 2:
The measurement system is designed with multi-functionality, where the same auxiliary winding or current sense transformer can serve multiple measurement purposes by reconfiguring the measurement path. This universal design allows a single physical component to perform multiple measurement functions, achieving high accuracy across different current ranges without proportionally increasing device complexity.
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 efficient and accurate determination of secondary side current over a wide range, improving signal quality and reducing power losses by optimizing the measurement path for both high and low output currents.
Implementation Method 1
a sensing circuit on a primary side of the isolation stage, which is magnetically coupled to a secondary side of the isolation stage
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an isolated converter (100) for providing a current supply to an LED load, comprising: a galvanic isolation stage (101); a sensing circuit (103) on a primary side of the isolation stage (101), which is magnetically coupled to a secondary side of the isolation stage (101); wherein the sensing circuit (103) is configured to receive a feedback signal that is proportional to a secondary side current; and a control unit (105) configured to determine an output current of the converter (100) based on the feedback signal; wherein at least one electrical characteristic of the sensing circuit (103) and/or the control unit (105) is adjustable to convert the feedback signal from a first ratio to a second ratio to the secondary side current.