Control device for a three-phase refrigerating machine and three-phase refrigerating machine that includes it
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Solution Overview
Problem
Refrigerating machines with three-phase power supply face increased complexity and cost due to the need for three-phase variable-speed electronic fans, which require additional power conversion and filtering, undermining the advantages of using single-phase fans.
Innovation Solution
A control device with an AC/DC converter that produces a DC bus voltage with three-level output, allowing single-phase variable-speed electronic fans to operate directly from the DC bus without needing DC/DC converters, and performs power factor correction, simplifying the system and making it independent of network voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If three-phase variable-speed electronic fans are used in refrigerating machines with three-phase power supply, then the fans can operate at variable speeds for forced convection heat transfer, but the system complexity and cost increase due to additional power conversion and filtering requirements
Solution Approach 1:
The patent combines the power conversion functions for both the compressor and the electronic fan into a single integrated control device. The AC/DC converter with three-level output topology serves dual purposes: powering the compressor through the DC/AC inverter and directly powering the single-phase electronic fan, eliminating the need for separate DC/DC converters and reducing overall system complexity.
Solution Approach 2:
The control device is designed with multi-functionality, where the AC/DC converter and its three-level output can serve multiple functions: providing power to the compressor, providing power to the electronic fan, and performing power factor correction for the entire system. This universal design eliminates the need for dedicated power conversion circuits for each component.
2Device complexity
If single-phase variable-speed electronic fans are used in refrigerating machines with three-phase power supply, then the structure and cost are reduced, but DC/DC conversion stages are needed to provide appropriate DC power supply voltage
Solution Approach 1:
The patent changes the voltage parameter at the output of the AC/DC converter by implementing a three-level output topology. This produces three distinct voltage levels (Vdc, V1dc, V2dc) from the same converter, allowing direct connection to single-phase fans without requiring additional DC/DC conversion stages. The voltage parameter is dynamically adjusted through the converter's switching configuration.
3Reliability
If dedicated machines are provided for different three-phase network voltages available in various countries, then the refrigerating machine can be optimized for specific voltage standards, but the manufacturing cost and inventory complexity increase
Solution Approach 1:
The AC/DC converter is designed with universal voltage compatibility, capable of accepting different three-phase input voltages (e.g., 380V, 400V, 415V) and adapting its operation accordingly. The control device automatically adjusts its parameters to match the input voltage, eliminating the need to manufacture separate machines for different voltage standards and allowing a single design to serve multiple markets.
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 solution simplifies the refrigerating machine structure, eliminates the need for DC/DC converters, and ensures independence from varying network voltages, reducing costs and complexity while enabling efficient operation of single-phase fans.
Implementation Method 1
an AC/DC converter (11) which is configured to produce a voltage increase and/or provide control for power factor correction (PFC) of the line current
Implementation Method 2
having a topology with three-level output so to provide at the output (12) also a first operating voltage (V1dc) and a second operating voltage (V2dc) whose sum is equal to the bus voltage Vdc
Implementation Method 3
provide control for power factor correction (PFC) of the line current
Data Source
Figure 1~3
Figure 4~8
AI summary
The present invention relates to a control device (10) for a refrigerating machine (100) with a three-phase power supply which comprises an AC/DC converter (11) having an output (12) and configured to produce a voltage increase so as to make available a DC bus voltage Vdc at the output (12) of the AC/DC converter (11). The AC/DC converter (11) has a topology with three-level output, so as to make available a first operating voltage V1dc and a second operating voltage V2dc whose sum is equal to the bus voltage Vdc.