Power losses calculation (heat dissipation)
Operation of the Pluto causes power losses that should be transferred to the surrounding environment as
heat. Heat dissipation depends on various parameters. Principally:
Motor RMS current: positive correlation.
DC bus voltage: positive correlation.
Other less relevant parameters affect also the power loss but are not considered in the graphs:
Air temperature, higher power semiconductor temperatures reduce their efficiency.
Motor speed. Faster motor speeds result in higher overall power loss since the input current is
greater. This increases conduction losses on the reverse polarity protection circuitry.
Current ratings
The Pluto Servo drive has no cold plate, so the board itself is the heatsink. Power losses cause the driver to
increase its temperature following the this formula:
Since T < 110ºC for safe operation, the maximum current rating can be calculated.
P
The thermal impedance of the Pluto will vary according to:
Air flow around the driver.
Position (vertical allows natural convection).
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