Digital Isolator Transformer Layout for Lower-Cost Inverter Control
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Solution Overview
Problem
The existing electronic devices controlling inverters face challenges in reducing the manufacturing cost of transformers and capacitors, particularly due to excessive performance requirements in low-side isolators, which lead to increased production costs.
Innovation Solution
The electronic device employs a configuration where the high-side and low-side isolators have different structures, with the low-side isolator having a smaller distance between inductors and fewer layers in the multilayer wiring layer, reducing the manufacturing cost without compromising performance, and using a three-chip configuration to simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the low-side isolator uses the same structure as the high-side isolator to ensure sufficient performance, then reliability is improved, but manufacturing cost increases due to excessive performance requirements
Solution Approach 1:
The patent applies local quality by making the low-side isolator structurally different from the high-side isolator. Specifically, the low-side isolator uses a smaller number of wiring layers and smaller inductor cross-sectional areas, matching its lower performance requirements. This resolves the contradiction by optimizing each isolator's structure to its actual needs rather than uniformly over-engineering both.
Solution Approach 2:
The patent changes key parameters of the low-side isolator: reducing the number of wiring layers from 5 to 3, and reducing the inductor cross-sectional area. These parameter changes directly reduce manufacturing cost while maintaining sufficient reliability for the low-side application where voltage stress is lower.
2Reliability
If the transformer uses a larger number of wiring layers to ensure sufficient insulation and performance, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by differentiating the wiring layer structure between high-side and low-side isolators. The high-side isolator uses 5 wiring layers for full insulation performance, while the low-side isolator uses only 3 wiring layers, matching its lower voltage stress requirements. This resolves the contradiction by optimizing insulation structure locally rather than uniformly across the entire device.
3Reliability
If the inductor cross-sectional area is increased to reduce series resistance, then performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by using different inductor cross-sectional areas for high-side and low-side isolators. The high-side isolator uses larger inductors to minimize series resistance under high voltage stress, while the low-side isolator uses smaller inductors with acceptable series resistance for its lower voltage application. This resolves the contradiction by matching inductor size to actual performance needs.
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 the manufacturing cost of the electronic device by optimizing the transformer structure and simplifying the chip configuration, ensuring sufficient performance while minimizing unnecessary performance additions and production complexity.
Implementation Method 1
a transformer (digital isolator) using a pair of inductors coupled inductively
Implementation Method 2
a transformer (digital isolator) using a pair of inductors coupled inductively and a capacitor
Data Source
AI summary
A second distance between a second lower inductor and a second upper inductor, which are components of a second transformer is smaller than a first distance between a first lower inductor and a first upper inductor which are components of a first transformer.