Heat Pipe Power Converter Control to Prevent Refrigerant Freezing
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Solution Overview
Problem
Existing power conversion devices suffer from inefficient cooling due to refrigerant freezing, which occurs when the air blower stops operating in low-temperature conditions, leading to excessive cooling and inability to circulate refrigerant, and in naturally-cooled devices, insufficient cooling occurs when refrigerant freezes due to surrounding temperatures.
Innovation Solution
A power conversion device with a controller that adjusts switching operations of switching elements based on load equipment status and ambient temperature to maintain optimal heat generation and prevent refrigerant freezing, using a heat pipe system with a refrigerant that vaporizes and liquefies to cool the elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the air blower operates based only on temperature threshold comparison, then the cooling system is simple to control, but the refrigerant freezes in low-temperature conditions causing cooling failure
Solution Approach 1:
The control method changes from simple temperature threshold comparison to a comprehensive control strategy that considers multiple parameters including temperature, load status, and air blower operation state. This allows the system to adjust the air blower operation duration and intensity based on the calculated heat generation amount, preventing refrigerant freezing while maintaining cooling effectiveness.
Solution Approach 2:
The system implements feedback control by continuously monitoring the temperature, load status, and air blower operation state, then adjusting the air blower control duration based on the calculated heat generation amount. This closed-loop control prevents refrigerant freezing by adapting the cooling intensity to actual thermal conditions.
2Temperature
If the air blower operates continuously in low-temperature conditions, then the switching elements are adequately cooled, but the refrigerant freezes and cannot circulate
Solution Approach 1:
The system dynamically adjusts the air blower operation duration and intensity based on real-time conditions including temperature, load status, and calculated heat generation. This dynamic control prevents excessive cooling that would cause refrigerant freezing while ensuring adequate cooling when needed, making the cooling intensity adaptable rather than fixed.
Solution Approach 2:
The control method uses periodic air blower operation with adjusted duration based on heat generation calculations. Instead of continuous operation, the air blower is controlled to operate for specific durations that match the actual cooling requirements, preventing refrigerant freezing while maintaining effective cooling of switching elements.
3Device complexity
If the power conversion device uses naturally-cooled design without air blower, then the device structure is simpler, but insufficient cooling occurs when refrigerant freezes due to surrounding temperature
Solution Approach 1:
The air blower control system serves multiple functions: it provides forced cooling when heat generation is high, prevents refrigerant freezing through intelligent duration control, and adapts to various operating conditions including different temperatures and load statuses. This multi-functional control strategy makes the cooling system versatile rather than single-purpose.
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
The device achieves high cooling performance by controlling switching operations to manage heat generation and prevent refrigerant freezing, ensuring effective cooling even in low-temperature environments.
Implementation Method 1
at least one heat pipe which is, with a refrigerant sealed therein, thermally connected to the plurality of switching elements and releases, to air outside of the housing, heat transferred from the plurality of switching elements
Implementation Method 2
using a heat pipe system with a refrigerant that vaporizes and liquefies to cool the elements
Data Source
AI summary
A power conversion device includes a power conversion circuit, a housing, at least one heat pipe and a controller. The power conversion circuit includes switching elements, converts electric power inputted thereto into electric power to be supplied to load equipment and supplies to the load equipment the electric power resulting from the conversion. The at least one heat pipe is exposed to air outside of the housing and releases, to the air, heat transferred from the switching elements. The controller controls switching operations of the plurality of switching elements such that a target voltage is outputted from the power conversion circuit and an amount of heat generation of the plurality of switching elements is obtained that is based on an operational status of the load equipment and a temperature of the air.