Isolated DC/DC Converter Control Circuit
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Solution Overview
Problem
Existing isolated DC/DC converters face limitations in achieving effective switching control, particularly when the frequency of control signals reaches maximum operating frequencies due to increased load, leading to insufficient control capabilities.
Innovation Solution
The proposed isolated DC/DC converter configuration includes a primary side control circuit and a secondary side control circuit that generate and transmit control signals with frequency and pulse width information, allowing for synchronized switching frequency control and peak current management through an insulated transmission circuit, using elements like capacitors or pulse transformers for signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the control signal frequency is increased to handle higher loads, then the power delivery capability is improved, but the control precision deteriorates when reaching maximum operating frequency
Solution Approach 1:
The control signal is segmented into two independent components: frequency information indicating the secondary side voltage state, and pulse width information indicating the timing for switching element operation. This segmentation allows the primary side control circuit to process both components separately, maintaining control precision even at maximum operating frequencies by using the pulse width parameter for precise switching timing control.
2Reliability
If a photocoupler is used for insulated signal transmission, then the insulation reliability is improved, but the device complexity and mounting area increase
Solution Approach 1:
The insulated signal transmission circuit is designed to perform multiple functions: it transmits both frequency information and pulse width information through the same insulated pathway. This multi-functionality reduces the need for separate transmission channels, thereby reducing device complexity and mounting area while maintaining insulation reliability through the consistent use of insulated elements.
3Device complexity
If only switching frequency control is implemented, then the control circuit simplicity is improved, but the control effectiveness deteriorates under heavy loads
Solution Approach 1:
The control system dynamically adjusts both the frequency and pulse width of the switching element based on real-time secondary side voltage conditions. The frequency indicates the voltage state while the pulse width provides dynamic adjustment capability for switching timing. This dynamic dual-parameter control maintains control effectiveness under varying load conditions while keeping the control circuit relatively simple.
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 enables robust switching control even at maximum frequencies, ensuring stable secondary side voltage regulation and reducing circuit area while maintaining high response speed and minimizing noise interference.
Implementation Method 1
an insulated transmission circuit that transmits, in an insulated manner, each piece of control information included in the control signal to the primary side control circuit
Data Source
AI summary
There is provided an isolated DC/DC converter including a primary side control circuit disposed on the primary side and switching a switching element connected in series with a primary side winding of a power transformer; a secondary side control circuit disposed on the secondary side and generating a control signal including first control information and second control information on the basis of the secondary side voltage; and an insulated transmission circuit transmitting, in an insulated manner, each piece of control information included in the control signal to the primary side control circuit. The primary side control circuit controls a switching frequency of the switching element on the basis of the first control information indicating the frequency of the control signal, and controls a peak value of a primary side current on the basis of the second control information indicating the pulse width of the control signal.