Isolated Converter Sensing Circuit With Frequency Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional isolated converters, such as synchronous flyback converters, experience non-linear frequency behavior that leads to unstable load current measurements across varying load voltage ranges, causing inaccuracies in load current regulation due to the sensitivity of measurement circuits to switching frequency and load voltage changes.
Innovation Solution
A sensing circuit with a correction module that uses a second-order correction formula to compensate for frequency-dependent behavior, calculating corrected load current information based on load current and voltage data, ensuring stable load current over the entire load voltage range by adjusting the feedback signal to the controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sensing circuit is used to measure load current in an isolated converter, then the circuit structure is simple, but the load current measurement becomes unstable and inaccurate when load voltage varies due to frequency-dependent behavior
Solution Approach 1:
The patent changes the parameters of the sensing circuit by introducing a frequency-dependent correction factor that adjusts the sensing behavior based on operating conditions. The correction module modifies the transfer function of the sensing circuit dynamically according to frequency variations caused by load voltage changes, thereby maintaining measurement accuracy across different operating points without requiring a completely different circuit architecture.
Solution Approach 2:
The patent replaces the conventional direct sensing approach with a corrected sensing method that uses mathematical compensation. Instead of modifying the physical sensing hardware to achieve frequency-independent behavior, the invention substitutes a correction module that processes the sensed signal digitally or analogously to compensate for frequency-dependent errors, thereby achieving accurate measurements without complex hardware modifications.
2Stability of the object's composition
If the sensing circuit is made frequency-independent to ensure stable load current measurement, then measurement stability improves, but the device complexity increases
Solution Approach 1:
The patent introduces a correction factor that dynamically adjusts sensing parameters based on frequency conditions. By changing the effective transfer function of the sensing circuit according to operating frequency, the system achieves stable load current measurements across varying load voltages without requiring a completely frequency-independent circuit design, thus balancing stability with acceptable complexity.
Solution Approach 2:
The correction module acts as an intermediary between the conventional sensing circuit and the control system. It processes the raw sensed signal and applies frequency-dependent correction before the signal is used for load current regulation, thereby decoupling the simplicity of the original sensing circuit from the requirement for stable measurements across all operating conditions.
3Manufacturing precision
If a correction module with second-order correction formula is implemented, then load current regulation accuracy improves across the whole load voltage range, but the control complexity increases
Solution Approach 1:
The patent implements a second-order correction formula that adjusts the sensing transfer function based on frequency-dependent parameters. This mathematical correction model accounts for the nonlinear behavior of the sensing circuit across different operating points, enabling high-precision load current regulation throughout the entire load voltage range by dynamically adjusting correction parameters rather than using a fixed simple model.
Solution Approach 2:
The correction module uses feedback from the sensed signal and operating conditions to dynamically adjust the correction applied to the load current measurement. By continuously monitoring frequency-dependent behavior and applying real-time correction, the system achieves high regulation accuracy without requiring overly complex control algorithms, as the correction is systematically derived from the known frequency response characteristics.
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 solution enables precise load current regulation within specified ranges, improving the accuracy and stability of isolated converters, particularly in LED converters, by compensating for frequency-dependent behavior in real-time, thus maintaining consistent performance from minimum to maximum load voltage.
Implementation Method 1
The load current (e.g., an LED current I LED ) is measured by monitoring the current i C through the capacitor C, via a current transformer comprising the magnetically coupled windings L S1 and L S2
Implementation Method 2
When the primary side switch S 1 is closed, there will be a primary side current i p through the primary side switch S 1 and the primary winding L 1 of the power transformer thereby the power transformer will be magnetized. When the primary side switch S 1 is being switched off and a secondary side current i s flows through the secondary winding L 2 as the power transformer will demagnetize.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to the field of switched mode power supplies (SMPS) and isolated converters, in particular for lighting technology. The present disclosure provides a sensing circuit 100 for an isolated converter 201. The sensing circuit 100 is configured to obtain load current information 101, and to obtain load voltage information 102. The sensing circuit 100 is further configured to determine, by a correction module 103 of the sensing circuit 100, corrected load current information 104 based on the load current information 101, the load voltage information 102 and a correction formula 105, wherein the correction formula 105 is configured to compensate a frequency dependent behaviour of the sensing circuit 100, and output the corrected load current information 104.