Insulated DC/DC Converter With Communication Transformer for PWM Feedback
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Solution Overview
Problem
Existing DC/DC converters using PWM control struggle to balance load responsiveness and noise immunity, as they either require frequent adjustments in switching frequency or a large number of components, while maintaining constant switching frequency is challenging.
Innovation Solution
An insulated DC/DC converter design that uses a communication transformer to maintain a constant PWM frequency, incorporating a secondary control circuit to generate PWM signals and a primary control circuit to switch the switching element based on feedback voltage comparisons, allowing for on-time adjustments to stabilize the secondary voltage while keeping the switching frequency constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If on-time control method is used to improve load responsiveness and reduce component count, then the switching frequency becomes unstable and noise immunity deteriorates
Solution Approach 1:
The control function is segmented between two independent control circuits: a primary control circuit that maintains constant switching frequency for noise immunity, and a secondary control circuit that adjusts on-time for load responsiveness. Each control circuit operates independently on its respective side of the transformer, eliminating the need to compromise either performance metric.
2Reliability
If PWM control with constant switching frequency is used to improve noise immunity, then load responsiveness and component efficiency deteriorate
Solution Approach 1:
A communication transformer serves as an intermediary between the primary and secondary control circuits, enabling the secondary circuit to transmit on-time adjustment information to the primary circuit without directly affecting the switching frequency. This mediator allows both control objectives to coexist by translating control signals across the isolation barrier.
3Productivity
If switching frequency is adjusted frequently to improve load responsiveness, then device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of adjusting the switching frequency directly in the primary control circuit to achieve load responsiveness, the invention inverts the approach by having the secondary control circuit determine the on-time parameters and transmitting this information back to the primary circuit. This inversion allows load responsiveness to be achieved without complicating the primary switching control.
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 design achieves the benefits of on-time control methods, such as high load responsiveness and reduced component count, while effectively managing noise and maintaining constant switching frequency, thereby improving the stability and efficiency of the DC/DC converter.
Implementation Method 1
a primary control circuit configured to switch the switching element at the PWM frequency based on information of the PWM signal transmitted from the secondary control circuit via the communication transformer
Implementation Method 2
generate a secondary voltage on a secondary side of a power transformer from a primary voltage on a primary side of the power transformer by switching a switching element connected to a primary winding of the power transformer
Data Source
AI summary
There is provided an insulated DC/DC converter configured to generate a secondary voltage on a secondary side of a power transformer from a primary voltage on a primary side of the power transformer by switching a switching element connected to a primary winding of the power transformer while insulating the primary side and the secondary side of the power transformer from each other, including: a communication transformer; a secondary control circuit including a PWM controller configured to generate a PWM signal of a constant PWM frequency based on the secondary voltage in a circuit arranged on the secondary side; and a primary control circuit configured to switch the switching element at the PWM frequency based on information of the PWM signal transmitted from the secondary control circuit via the communication transformer in a circuit arranged on the primary side.