Motor Power Conversion Device Thermal Management
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Solution Overview
Problem
The existing power conversion devices for motors face challenges in downsizing due to heat dissipation issues, mechanical strength concerns, and increased manufacturing costs, which limit the operational range and efficiency of the motor and its integrated systems.
Innovation Solution
A power conversion device is designed with a semiconductor module mounted on the stator side of the motor, incorporating an overheat detection element and a heat spreader for effective thermal management, which allows for accurate temperature monitoring and prevention of element fractures, while also simplifying the mounting process and reducing package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If surface mount ICs are mounted on a printed circuit board by reflow soldering to achieve downsizing, then the package size is reduced, but the mechanical strength of the soldered portion decreases and distortion increases due to heat generation
Solution Approach 1:
The patent segments the mounting process into two distinct phases: first mounting the IC by reflow soldering to achieve downsizing, then reinforcing the soldered portion by injecting molten metal into the solder joints. This segmentation allows the system to benefit from both the size reduction of reflow soldering and the strength enhancement of additional metal infiltration.
Solution Approach 2:
The patent changes the physical state and composition parameters of the solder joint by introducing molten metal that infiltrates the existing solder connections. This parameter change transforms the solder joint from a potentially weak reflow-soldered connection to a reinforced hybrid joint with improved mechanical strength and thermal resistance.
2Temperature
If sheet-metal parts are added for heat dissipation and separate soldering is performed, then heat dissipation capability is improved, but manufacturing cost increases due to additional soldering steps
Solution Approach 1:
The patent merges the heat dissipation function with the existing printed circuit board structure by forming metal plates directly on the board using the same injection molding process that creates the housing. This integration eliminates the need for separate sheet-metal heat sinks and additional soldering operations, reducing manufacturing complexity and cost while maintaining effective heat dissipation.
Solution Approach 2:
The printed circuit board is designed to serve multiple functions simultaneously: it provides electrical connections, structural support, and heat dissipation through the integrated metal plates. This multi-functionality eliminates the need for separate dedicated heat dissipation components and reduces the overall number of manufacturing steps.
3Volume of moving object
If IC is mounted close to stator for downsizing, then package size is reduced, but temperature rise increases causing element fractures
Solution Approach 1:
The patent introduces metal plates as thermal intermediaries between the IC and the surrounding environment. These plates act as heat spreaders that distribute the thermal load from the IC over a larger area, preventing localized temperature rises that could cause element fractures while allowing the IC to be positioned close to the stator for downsizing.
4Ease of manufacture
If reflow soldering is used to couple IC and circuit board, then manufacturing process is simplified, but mechanical strength decreases compared to hand soldering
Solution Approach 1:
The patent performs a preliminary reflow soldering operation to establish the basic IC-to-board connection, then follows up with an additional action of injecting molten metal to reinforce the joint. This preliminary action followed by reinforcement allows the manufacturing process to benefit from the automation of reflow soldering while achieving mechanical strength comparable to or exceeding hand soldering.
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 the power conversion device to prevent operational range reduction due to temperature rises, enhance mechanical strength, and facilitate downsizing of the motor and its associated systems, such as air conditioners, by improving thermal management and reducing manufacturing costs.
Implementation Method 1
a molten metal is injected to infiltrate a soldered portion between the IC and the printed circuit board
Implementation Method 2
the printed circuit board and the stator are mechanically coupled by a mold resin
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
To obtain a power conversion device in which a board to be mounted is downsized by downsizing of elements or an arrangement configuration of the elements, a motor including the same, an air conditioner having the motor incorporated therein, and a ventilation fan having the motor incorporated therein. Included are a printed circuit board 1, whose mounting surface is opposite to an annular surface formed by an annular stator 3 that constitutes a motor 61, arranged to be separated from the annular surface with a predetermined distance, and mounted with a Hall element 6 that detects a rotation position of a rotor 16 of the motor 61 on a mounting surface on a side of the stator 3; an inverter IC 2 that is mounted on the mounting surface on the side of the stator 3 of the printed circuit board 1 to supply a high-frequency current to the stator 3; and an overheat detection unit 14 that is mounted on the mounting surface on the side of the stator 3 of the printed circuit board 1 and detects an overheated state of the inverter IC 2. When the overheat detection unit 14 detects an overheated state, the inverter IC 2 restricts or stops a current to be supplied to the stator 3.