Electric-power control device, electric motor, air-conditioning apparatus, and method for manufacturing electric motor
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Solution Overview
Problem
Conventional electric-power control devices for electric motors suffer from heat transmission issues, where heat generated by the power IC is directly transmitted to the microcomputer via a shared ground electrode, leading to increased microcomputer temperature.
Innovation Solution
The electric-power control device features a substrate with separate ground pattern portions for the power semiconductor module and microcomputer, connected only through a specific connection portion, which reduces heat transmission by increasing the distance and minimizing the ground pattern width, thereby isolating the heat sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ground electrode pattern is used to connect both the power IC and microcomputer, then the device complexity is reduced and manufacturing is simplified, but heat generated by the power IC is directly transmitted to the microcomputer causing temperature rise
Solution Approach 1:
The ground electrode pattern is divided into two separate patterns: a first ground pattern connected to the power IC and a second ground pattern connected to the microcomputer. This segmentation prevents heat generated by the power IC from being directly transmitted to the microcomputer through the ground electrode, thereby reducing the microcomputer temperature while maintaining manufacturing simplicity.
Solution Approach 2:
A resin layer is introduced as an intermediary material between the first and second ground patterns. The resin has lower thermal conductivity compared to the ground electrode material, acting as a thermal barrier that blocks heat transmission from the power IC to the microcomputer while still allowing electrical isolation.
2Temperature
If separate ground patterns are used for power IC and microcomputer, then heat transmission is reduced, but the device complexity increases
Solution Approach 1:
The ground electrode pattern is segmented into two distinct patterns positioned at different locations on the substrate. The first ground pattern is located near the power IC while the second ground pattern is located near the microcomputer, creating physical and thermal separation between the two components.
Solution Approach 2:
The solution moves from a two-dimensional planar connection to a three-dimensional arrangement by utilizing the vertical dimension through the resin layer. The resin layer positioned between the ground patterns creates a thermal barrier in the vertical direction, effectively blocking heat transmission while maintaining a relatively simple overall structure.
3Reliability
If the ground electrode is made wider to improve electrical connection, then electrical conductivity is improved, but heat transmission to the microcomputer increases
Solution Approach 1:
The ground electrode is segmented into separate patterns for the power IC and microcomputer. Each ground pattern can be optimized for its specific function: the first ground pattern near the power IC can be wider to handle high current, while the second ground pattern near the microcomputer can be narrower to minimize heat transmission.
Solution Approach 2:
The resin layer serves as a thermal intermediary that blocks heat transmission between the ground patterns. This allows the first ground pattern to be made wider for better electrical connection and heat dissipation at the power IC, while the second ground pattern remains narrow to prevent heat from reaching the microcomputer.
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 effectively reduces the microcomputer's temperature, allowing for higher efficiency and reliability of the electric motor operation while enabling high-speed microcomputer operation without increasing the guaranteed temperature, thus reducing costs and improving performance.
Implementation Method 1
heat generated at the power IC is directly transmitted to the microcomputer via the ground electrode
Data Source
AI summary
An electric-power control device including a substrate of an annular shape in which a through hole is formed and a connector is arranged in a peripheral part, the electric-power control device driving an electric motor. On the substrate, a power semiconductor module is mounted on a first region on one side relative to a straight line connecting the center of the through hole to the center of the connector, and a microcomputer is mounted on a second region on the other side. Furthermore, a first ground pattern part that is formed extending from the power semiconductor module toward the connector in the first region and a second ground pattern part that is formed extending from the microcomputer toward the connector in the second region are provided on the substrate.