Transformer-Based Isolation Control for Power Electronics
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Solution Overview
Problem
Power electronics systems require efficient communication across safety isolation boundaries without the need for costly and space-consuming communication devices like optocouplers, especially in low-power applications where cost and space are critical, while maintaining stable switching frequencies to minimize noise and transient performance issues.
Innovation Solution
The system employs controllers to determine the durations of ringing and charging times by detecting signals through a transformer, allowing for indirect communication without separate communication devices, and modulating the on-time of the primary switch to maintain a stable switching frequency and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If optocouplers or capacitive/transformer-based couplers are used for communication across safety isolation, then information can be transmitted from secondary side to primary side, but system cost increases, space is consumed, and system reliability is reduced
Solution Approach 1:
The patent extracts the communication function from separate dedicated devices (optocouplers, capacitive couplers) and integrates it into the existing transformer structure. The transformer not only performs power isolation and transmission but also carries communication signals through its windings, eliminating the need for separate communication components across the safety isolation boundary.
Solution Approach 2:
The transformer is given multiple functions: it simultaneously performs power isolation, power transmission, and communication signal transmission. By using the transformer's windings to carry both power and communication signals, the system achieves multi-functionality with a single component, reducing overall system complexity and component count.
2Loss of information
If optocouplers or capacitive/transformer-based couplers are used for communication across safety isolation, then information can be transmitted from secondary side to primary side, but system cost increases
Solution Approach 1:
The transformer is given multiple functions: it simultaneously performs power isolation, power transmission, and communication signal transmission. By using the transformer's windings to carry both power and communication signals, the system achieves multi-functionality with a single component, reducing overall system complexity and component count.
Solution Approach 2:
The patent merges the communication function with the power transformation function in the transformer. The secondary controller modulates the primary switch's on-time based on output voltage feedback, and this control information is transmitted back to the primary controller through the transformer's magnetic coupling, combining power and communication paths.
3Productivity
If variable switching frequency is used to adapt to different operating conditions, then power delivery can be optimized, but noise and transient performance issues increase
Solution Approach 1:
The patent implements a feedback control mechanism where the secondary controller measures the output voltage and uses this information to modulate the primary switch's on-time. This feedback loop allows the system to adapt to different operating conditions while maintaining stable switching frequency, as the control is achieved through duty cycle adjustment rather than frequency variation.
Solution Approach 2:
The system dynamically adjusts the primary switch's on-time (duty cycle) based on real-time output voltage feedback while maintaining a constant switching frequency. This dynamic duty cycle control allows the power delivery to be optimized for different load conditions without introducing the noise and transient issues associated with variable frequency operation.
4Reliability
If separate communication devices are used for transmitting control signals, then communication reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The transformer is given multiple functions: it simultaneously performs power isolation, power transmission, and communication signal transmission. By using the transformer's windings to carry both power and communication signals, the system achieves multi-functionality with a single component, reducing overall system complexity and component count.
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 approach reduces system complexity, cost, and noise, while maintaining stable power delivery and transient performance by eliminating the need for optocouplers and ensuring constant switching frequencies, which is particularly beneficial for low-power applications.
Implementation Method 1
a secondary winding of the transformer magnetically coupled to the primary winding of the transformer
Data Source
AI summary
In some examples, a method includes measuring, by a secondary controller, an output voltage and determining, by the secondary controller, a duration for a ringing time based on the output voltage. In some examples, the method further includes delivering, by the secondary controller, a non-enabling control signal to a secondary switch during the ringing time and measuring, by a primary controller, a duration of the ringing time. In some examples, the method also includes determining, by the primary controller, a duration for a charging time based on the duration of the ringing time and delivering, by the primary controller, an enabling control signal to a primary switch during the charging time.