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Water Cooled AKD-N12 with Heat Sink

Background

In order to use the AKD-N12 continuously with a full load, it is needed to ensure a RTHgesamt ≤ 0,2 K/W for the complete system ([1]). The AKD-N without a heat sink provides an RTH of 0,05 K/W. Therefore an additional RTH ≤ 0.15 K/W needs to be ensured in order to provide sufficient heat dissipation. This can be achieved by using a water cooled heat sink.

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This article supplies further information about a water cooled option of the 12 A AKD-N and further information about the validation tests.

Heat Sink

As an example, the 180-10-6C heat sink from Wakefield-Vette provides the required RTH ≤ 0.15 K/W. Within below graph (pic. 1) you can estimate that a flow volume of 1 l/min is sufficient in order to ensure proper cooling for the AKD-N12.

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The graph shows that the heat sink with a flow volume of 1 l/min provides an RTH=0,1 K/W which is below the required max. value 0,15K/W.

The validation of this theory will be provided below.

Heat Sink Validation

The Validation of the heat sink takes places with an AKD-C supplied with 480VAC, which powers an AKD-N12.

  • Ambient temperature 40°C.
  • Cooling water temperature: steady 25°C.

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Different flow volumes between 0,5 and 5 l/min have been used to measure the temperature behavior of the power and control board, as well as the heat sink's input and output water temperature (pic. 3 and 4).

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Based on the measured temperatures the following flow volumes the R­TH can be determined for the complete system [1].

Flow Volume [l/min] 0,5 1 2 3 5
RTH [K/W] 0,165 0,129 0,105 0,099 0,093

The test validates that the suggested heat sink ensures a proper cooling for an AKD-N12. The flow volume should not be below 1 l/min as otherwise the efficiency decreases rapidly.

Sources

[1] Data sheet: http://www.wakefield-vette.com/Portals/0/resources/datasheets/180-10,180-11.pdf