DE1809770A1 - Process for dissipating the heat loss from thyristors arranged in electronic frequency converters of refrigeration machine systems - Google Patents

Description

LINDE AKTIENGESELLSCHAFT

(S 301) s 68/08 3

So / Kp

November 19, 1968

Process for dissipating heat loss in electronic frequency converters from refrigeration systems arranged thyristors

The invention relates to a method for dissipating the waste heat of thyristors, which are arranged in electronic frequency converters of refrigeration systems.

Various compressors for refrigeration systems, which are driven by asynchronous motors, have to be controlled the cooling capacity reach speeds that are far above the speed given by the mains frequency. Example

009824/0880

-2- LINDE AiCTIENQESELLSCHAFT

wisely these are turbo compressors * screw compressors etc.

For this purpose, a mechanical one was previously used between the motor and the compressor Gearbox or a three-phase high-frequency motor was used as the drive motor separately installed frequency machine converter set is fed.

Because of its significant advantages over these two possibilities, a contactless one is used for speed control today working electronic frequency converter used. With an electronic frequency converter can Energy can be transferred between two alternating current networks, which are different in their frequency and phase position. This means that three-phase motors can be fed from a 50 Hertz network and operate with a changed frequency and thereby control their speed.

Such an electronic frequency converter generally consists of a line-commutated converter (rectifier), direct current intermediate circuit and alternating current. The controlled semiconductor valves are high-performance thyristors. These thyristors develop a relatively high stei- with the strength of the current through it hindurohtretenden ^y

-> LINDE AKTIENGESELLSCHAFT

Low heat loss, which was previously dissipated by cooling the thyristors with air at room temperature.

However, this type of dissipation of the heat loss is essential Disadvantage. The poor heat transfer in air results in an unfavorable design and low load capacity the thyristors. A special fan is required for air cooling. Also, it can be due to sudden sharp increase the current strength can easily overload the thyristors.

The invention is based on the object of a simple and

specify economical method for cooling the thyristors, which does not have the shortcomings of the known method.

This object is achieved in that the heat loss through a cooling liquid, preferably at temperatures below the ambient temperature.

As a result of the good heat transfer to the liquid, liquid cooling and especially liquid temperatures below the ambient temperature, i.e. in generally at low temperatures, which dissipate the heat loss of the thyristors very well. Through this

009824/0880

-4- LINDE AKTIENGESELLSCHAFT

their performance can be increased significantly and one can at given load with a smaller number of γοη thyristors get by or increase the load on a given thyristor. So you can increase the performance of the thyristors significantly without having to expand their structure.

The dissipation of the heat loss at low temperatures is extremely beneficial, since the current density increases as the thyristor temperature falls. The lowest temperature of thyristors today is about -JO ⁰ Ci, at higher temperatures- ·. There are technological difficulties with conventional thyristors.

Only the liquid cooling of the thyristors enables their optimal arrangement with respect to one another with a view to being effective Cooling of each individual thyristor as well as a good adaptation of the cooling to the load. This is due to the fact that only b @ i Use of cooling liquid the cooling of the thyristors is properly manageable and controllable.

According to a particularly favorable development of the invention the cooling liquid is used as a partial flow from a liquid or liquid-vapor cycle of the refrigeration system branched off, the size of this branch flow in Depending on the thyristor temperature is set.

0.09824 / 0880

-5- LINDE AKTIENGESELLSCHAFT

In this way, a subset of the anyway The cooling capacity generated by the refrigeration system is used for thyristor cooling ^ whereby the cooling medium is advantageous After it has been heated by the thyristors, it is returned to the circuit from which it was taken for regeneration is fed. Setting the size of the branch current. for thyristor cooling takes place depending on the thyristor temperature and is generally about 2 to a maximum of 10 # the size of the main current, depending on the thyristor load. It is advisable to adjust the amount of cooling liquid with a vpn of the - thyristor temperature dependent - temperature of the adjust the thyristors of the heated cooling medium controlled control valve. By changing the amount of coolant can always be one even with very large and very rapid load changes, for example from 100 to 3000 A. Maintain essentially constant thyristor temperature.

In the case of cold water units, the cooling liquid can be a branch flow of the cold water circuit and through the heat sinks the thyristors are led.

With regard to the requirement for the lowest possible cooling temperatures In systems with refrigerant liquid cooling of the drive motor, the result is an even more favorable

009824/0880

-6- LINDE AKTIENGESELLSCHAFT

Implementation of the invention when the cooling liquid is a branch flow of the refrigerant liquid circuit for engine cooling and is passed through the thyristor heat sinks. This type of thyristor cooling is also very advantageous because that when the motor starts up, the entire flow of liquid is passed through the heat sinks of the thyristors can, since the cooling of the drive motor does not need to start until some time later.

The invention can be particularly advantageous thereby train that the cooling liquid as a 2t \ * intrinsic flow of the actual Refrigerant circuit tier refrigerating machine system taken from the condenser or refrigerant collector and in The thyristor heat sinks are injected or pumped through the heat sinks. That in the heat sinks of the thyristors injected refrigerant or refrigerant pumped through it evaporates in this * whereby it is not only through its perceptible cold through its evaporation cold cools the thyristor. This results in a very economical type of cooling, especially because of that. " because basically smaller amounts of cooling medium have to be circulated for Thyrisfcorkühlung.

Finally, if the compressor is flooded, the thyristor cooler ^j x: s the entire}; » electronic

00Ü8 / 4 / 08SÜ

""'' ■ "■ ■ ■ '■■■ >' ■ '-' '■■' ■■ -" ■ ■ ■■■: '■ "·"'>'":''■ III ·! RI "! '"W lliijill!

-7- lindeaktienqesellschaft

Frequency converter or at least the thyristors in the Arrange refrigerant liquid in the evaporator of the refrigerating machine system. All pipelines are omitted here and other accessories for thyristor cooling using one of the branch flow methods described above.

An electronic frequency converter provided with thyristors cooled according to the invention enables an accurate frequency converter and economical regulation of the cooling capacity of a refrigeration system in a wide range.

6 claims

009824/0980

Claims (6)

-S- LINDEAICTIEMGESELLSCHAFT (s 301) s 68/083 So / Kp 19. 11. 1968 Patent claims 1. Method for dissipating heat loss from thyristors,., which are arranged in electronic frequency converters of refrigeration; r, a £ chinenanlagen, characterized by Ate the heat loss through a cooling liquid, preferably at temperatures below ambient temperature. 2. The method according to claim 1, characterized in that the cooling liquid as part of the flow of a liquid ;: .- ·, · :. Liquid Dari.pf circuit of the refrigerating machine system is branched off, the size of this branch current being set in terms of temperature. 3 · The method according to claim 2, characterized in that the cooling liquid is a branch flow of the cold water circuit and is passed through the thyristor heat sinks « 009824/0880 BATH ORIGINAL ₉ LINDE AKTIENGESELLSCHAFT 4. The method according to claim 2, characterized in that the cooling liquid is a branch flow of the refrigerant-liquid cycle for the motor cooling and is passed through the thyristor heat sinks. 5. The method according to claim 2, characterized in that the cooling liquid as a branch stream of the actual The refrigerant circuit of the refrigerating machine system is taken from the condenser or refrigerant collector and injected into the thyristor heat sinks or pumped through the heat sinks. 6. The method according to claim 1, characterized in that the entire electronic frequency converter or at least the thyristors in the refrigerant liquid in the Evaporator of the refrigeration machine is arranged. 009824/0880