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Cooling requirements
To ensure you get the maximum performance from your Gen4 controller:
Keep it away from other heat generating devices on the vehicle
Maintain its ambient operating temperature below the specified maximum (see 'Operating
environment' on page 4-8)
To obtain maximum performance it is important to keep Gen4's base plate within the operating
temperature range. To do this, mount Gen4 to a surface capable of conducting away the waste
heat. Finned heatsinks are considerably better at doing this than flat plates. For example, a
finned heatsink used at Sevcon has a footprint of 330mm x 200mm and thermal resistance of
0.3°C/W, whereas a plate approximately 420 mm x 270 mm x 9.5 mm will give approximately the
same thermal performance (0.3°C/W). Ratings achievable with conductive heatsinking are
shown in Figure 10 on page 4-4.
In Sevcon's experience the thermal resistance of the stand-alone Gen4 packages and
achievable thermal resistances to ambient using conductive heatsinking are as shown in the
table below. These are given as a guide: actual performance in an application must be verified.
Gen4 Size
Thermal
resistance without
additional
heatsinking (°C/W)
Size 2
0.7
Size 4
0.6
Size 6
0.5
Cooling performance is affected by mounting surface flatness and the thermal transfer between
mounting surface and Gen4. Ensure your application of thermal grease is effective and your
mounting surface meets the flatness figures as described in the 'Mounting' section above.
Doc. # 177/52701
Rev. 3.3
Thermal resistance
achievable with finned
heatsink (°C/W)
0.5
0.3
0.2
Installation
Dimension of finned
heatsink (W x L)
250mm x 180mm
330mm x 200mm
330mm x 280mm
3-5
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