Refrigerant-Cooled Power Module Control for Leakage Noise Reduction
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Solution Overview
Problem
Refrigerant coolers connected to power elements in refrigeration systems can cause noise issues due to high-frequency current leakage, which is difficult to manage with existing noise filters, leading to increased costs and system noise.
Innovation Solution
A refrigeration apparatus with a refrigerant circuit that includes a power module, a drive motor, a rectifier circuit, and a refrigerant cooler, where the control section manages the switching elements to reduce high-frequency current leakage by implementing a carrier cycle with no switching operations and adjusting the motor terminal voltage waveform to minimize switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a refrigerant cooler is used to cool the power module, then the cooling effect is improved, but high-frequency current leakage occurs causing noise problems
Solution Approach 1:
A heat dissipation plate is introduced as an intermediary between the power module and the refrigerant cooler. The heat dissipation plate serves as a thermal conductor to transfer heat from the power module to the refrigerant cooler, while being electrically isolated to prevent high-frequency current leakage to the refrigerant cooler and ground, thus resolving the contradiction between cooling effectiveness and noise reduction
Solution Approach 2:
The harmful function of the refrigerant cooler (providing a ground path for high-frequency current) is extracted and separated from its useful function (cooling the power module). By introducing the heat dissipation plate as an intermediate thermal conduction path, the cooling function is preserved while the harmful electrical conduction path is eliminated
2Object-generated harmful factors
If a noise filter is added to reduce high-frequency current leakage, then noise is reduced, but system cost and complexity increase
Solution Approach 1:
The design converts the potential harm of direct thermal coupling into a benefit by using the heat dissipation plate structure. The same structural arrangement that could provide electrical conduction is designed to provide only thermal conduction, turning the cooling system into a built-in noise solution without requiring additional noise filter components
Solution Approach 2:
The cooling system itself serves the dual purpose of cooling and noise reduction. The heat dissipation plate structure enables the refrigerant cooler system to automatically prevent high-frequency current leakage without requiring separate noise filtering subsystems, making the system self-sufficient for both cooling and electromagnetic compatibility
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, eliminating the need for additional noise filters and reducing inverter losses, thus enhancing system efficiency and cost-effectiveness.
Implementation Method 1
a refrigerant cooler (81) in which a refrigerant in the refrigerant circuit (10) flows and which cools the power module (61)
Data Source
AI summary
A refrigeration apparatus includes a refrigerant circuit with a compressor, a power module, a refrigerant cooler in contact with the power module, and an IPM motor which drives the compressor. A refrigerant in the refrigerant circuit flows through the refrigerant cooler, and cooling of the power module is performed by dissipating heat to the refrigerant flowing in the refrigerant cooler. A controller in the refrigeration apparatus outputs a driving signal to a drive circuit to reduce the number of switching operations of switching elements by performing overmodulation control such that there exists a carrier cycle in which no switching is performed.