Refrigerating apparatus
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Solution Overview
Problem
Refrigerant coolers connected to conductive materials in refrigeration systems can form capacitors, leading to high-frequency current leakage and noise issues due to potential variations in electrode potentials, which existing noise filters attempt to mitigate but at increased cost and complexity.
Innovation Solution
Implementing a refrigeration apparatus with a control section that performs overmodulation control, reducing switching operations in the inverter circuit, and using an interior permanent magnet motor to adjust motor terminal voltage, thereby minimizing high-frequency current leakage through the refrigerant cooler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a refrigerant cooler made of conductive material is used to cool the power element, then the cooling effect is improved, but high frequency current leakage and noise problems occur
Solution Approach 1:
An insulating member is introduced as an intermediary between the power element and the refrigerant cooler. This insulating member electrically insulates the power element from the cooler while still allowing thermal conduction to occur, thereby preventing high frequency current leakage paths while maintaining effective cooling of the power element.
Solution Approach 2:
The contact interface between the power element and refrigerant cooler is segmented into distinct functional layers: a thermal conduction portion that allows heat transfer and an insulating portion that blocks electrical current leakage. This segmentation enables independent optimization of thermal and electrical properties at different locations of the contact interface.
2Object-generated harmful factors
If a noise filter is added to reduce high frequency current leakage, then noise problems are improved, but device complexity and cost increase
Solution Approach 1:
The insulating member, originally intended to prevent electrical discharge breakdown, inadvertently serves as an effective barrier against high frequency current leakage. This converts a protective measure against one type of electrical failure into a solution for noise reduction, eliminating the need for separate noise filtering components.
3Temperature
If the power element is directly attached to the refrigerant cooler, then the cooling efficiency is improved, but electrical discharge breakdown risk increases
Solution Approach 1:
The insulating member serves as a mediator that simultaneously addresses both cooling efficiency and electrical discharge resistance. It provides a thermal conduction path for heat removal while creating an electrical insulation barrier that prevents discharge breakdown, allowing the power element to be effectively cooled without direct electrical contact to the conductive refrigerant cooler.
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
Effectively reduces high-frequency current leakage and associated noise without the need for additional noise filters, thereby simplifying the system and reducing costs while maintaining efficient cooling.
Implementation Method 1
a refrigerant cooler (81) in which a refrigerant in the refrigerant circuit (10) flows and which cools the power module (61)
Implementation Method 2
a capacitor is formed inside the power element between the internal electrode and the metal plate, with the insulator serving as a dielectric. If the power element is attached to a refrigerant cooler made of a conductive material, a capacitor is formed inside the power element between the metal plate and the refrigerant cooler
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power module (61) is attached to a refrigerant cooler (81) in contact with the refrigerant cooler (81), and cooling is performed by dissipating heat to the refrigerant flowing in the refrigerant cooler (81). A controller (60) outputs a driving signal to a drive circuit (31) to reduce the number of switching operations of switching elements (37).