Adaptive ON-Time Control in Isolated Voltage Converters
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Solution Overview
Problem
Conventional isolated voltage converters face challenges in communicating an OFF signal across the transformer during the ON phase due to time-varying currents, which complicates the regulation of the output voltage and requires additional circuitry.
Innovation Solution
An adaptive ON-time generation circuit is introduced, which determines the length of the ON phase based on the load condition by using a WAKE signal to adjust the ON time, eliminating the need for direct OFF signal communication through the transformer by adapting the ON time in response to load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional isolated voltage converters use time-varying currents through the transformer during the ON phase, then energy transfer from primary to secondary coil is achieved, but communication of OFF signal across the transformer becomes complicated
Solution Approach 1:
The patent extracts the OFF signal communication function from the transformer by using a separate RC coupled amplifier stage. The transformer is dedicated solely to energy transfer, while the OFF signal is communicated through the RC coupling network, eliminating the complexity of communicating control signals through the time-varying magnetic field of the transformer.
Solution Approach 2:
The patent introduces an RC coupled amplifier as an intermediary mechanism for OFF signal communication. This intermediary stage couples the primary and secondary sides without requiring direct magnetic coupling for control signals, simplifying the overall system by separating energy transfer and control signal communication functions.
2Reliability
If additional circuitry is added to communicate OFF signals through the transformer, then output voltage regulation is achieved, but device complexity increases
Solution Approach 1:
The patent merges the OFF signal communication with the existing RC coupling network used for other control functions. By utilizing the available RC coupled amplifier stage, the design achieves output voltage regulation without adding separate dedicated circuitry for OFF signal communication, thus maintaining simplicity while ensuring reliable regulation.
3Productivity
If the switch network operates at relatively high rates to generate switching waveforms, then energy transfer efficiency is improved, but the complexity of controlling the switch network increases
Solution Approach 1:
The patent employs periodic switching of the transistor at relatively high rates to efficiently transfer energy from the primary to secondary coil. The RC coupled amplifier generates periodic control signals that drive the switch network, maintaining high switching frequencies for efficient energy transfer while the automated periodic nature of the control reduces operational 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 solution allows for efficient regulation of the output voltage by dynamically adjusting the ON time based on load conditions, reducing the need for additional circuitry and improving the converter's ability to manage varying load demands.
Implementation Method 1
transformers transfer energy between the primary and secondary cons using time-varying currents
Data Source
AI summary
A voltage converter includes a switch network, a rectifier, and a transformer coupled between the switch network and the rectifier. The voltage converter includes an adaptive ON-time generation circuit having a control input and a control output, the control input. The adaptive ON-time generation circuit is configured to receive a WAKE signal to turn ON the switch network, generate a signal indicative of an OFF time of the switch network, and determine an ON time for the switch network based on the signal indicative of the OFF time.