Isolated DC-DC Converter Tertiary Coil Voltage Detection
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Solution Overview
Problem
The existing isolated DC-DC converters face challenges in maintaining a proportional relationship between the output voltage and detected voltage due to parasitic diode effects and LC resonance, leading to inaccurate voltage stabilization, especially with changes in input voltage and temperature.
Innovation Solution
Incorporating a commutation-side synchronous rectifier in the tertiary-side rectifying and smoothing circuit that is switched on when the main switching device is off, preventing the induced voltage from the tertiary coil from affecting the detected voltage, thus maintaining a stable correlation between the output and detected voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tertiary-side rectifying and smoothing circuit is used to detect output voltage, then output voltage detection is achieved, but the proportional relationship between output voltage and detected voltage is broken due to parasitic diode effects and LC resonance
Solution Approach 1:
The patent extracts and removes the harmful voltage components generated by parasitic diodes and LC resonance from the detected voltage signal. By identifying these unwanted voltage components and eliminating them through circuit design modifications, the patent restores the proportional relationship between output voltage and detected voltage, thereby improving measurement precision while maintaining reliability
Solution Approach 2:
The patent introduces an intermediary calculation process that computes the harmful voltage components separately and subtracts them from the total detected voltage. This mediator approach allows the system to account for parasitic effects without breaking the proportional relationship, enabling accurate output voltage detection while maintaining signal reliability
2Loss of energy
If the main switching device is switched off, then energy recovery and transformer resetting are achieved, but LC resonance generates harmful pulse voltages that affect detected voltage
Solution Approach 1:
The patent converts the harmful LC resonance pulse voltage into a calculable and removable component. By modeling the resonance behavior and calculating its contribution to the detected voltage, the patent transforms this harmful effect into a known quantity that can be subtracted from the total signal, thereby recovering energy efficiently while eliminating the harmful voltage's impact on detection accuracy
3Adaptability or versatility
If input voltage or temperature changes, then adaptability is improved, but the correlation between output voltage and detected voltage becomes unstable
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the detected voltage, calculates the harmful components based on current operating conditions (input voltage and temperature), and adjusts the compensation accordingly. This feedback loop maintains the proportional relationship between output and detected voltages across varying conditions, ensuring measurement precision is preserved while adapting to different input ranges and temperatures
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 configuration ensures accurate control of the output voltage, improving the stability and accuracy of the isolated DC-DC converter by preventing unnecessary voltage components from breaking the correlation between output and detected voltages, even with changes in input voltage and temperature.
Implementation Method 1
a transformer (2) that includes a primary coil (N1), a secondary coil (N2), and a tertiary coil (N3) which are electromagnetically coupled
Implementation Method 2
A secondary-side rectifying and smoothing circuit (5) is provided on the side of a secondary coil N2 of the transformer 2. The secondary-side rectifying and smoothing circuit 5 includes a rectification-side synchronous rectifier (for example, a MOS-FET) 6, a commutation-side synchronous rectifier (for example, a MOS-FET) 7
Data Source
AI summary
A secondary-side rectifying and smoothing circuit rectifies and smoothes an output voltage from a secondary coil of a transformer and outputs a rectified and smoothed voltage to the outside. A tertiary-side rectifying and smoothing circuit rectifies and smoothes an output voltage from a tertiary coil to produce a direct-current voltage and detects and outputs the direct-current voltage as a detected voltage of the output voltage from the secondary-side rectifying and smoothing circuit. A control circuit controls the switching operation of a main switching device on the basis of the detected voltage so that the output voltage is stabilized. The secondary-side rectifying and smoothing circuit includes a rectification-side synchronous rectifier and a commutation-side synchronous rectifier as rectifying devices. The tertiary-side rectifying and smoothing circuit includes a commutation-side synchronous rectifier as a rectifying device that rectifies the output voltage from the tertiary coil, the commutation-side synchronous rectifier being switched on when the main switching device is turned off.