Mounting and Cooling - LPi

Mounting and cooling considerations for the microDRIVE LPi units.

Details and recommendations for mounting the units within a given application can be found below.

The microDRIVE LPi offers 6 mounting holes to secure the unit to your cooling solution/aircraft. These are best suited to M2 socket head bolts. Ensure you use a tightening torque appropriate to the fastener and mounting material you are using. The mounting holes accommodate a head diameter/ washer diameter of 4mm.

The correct installation of the microDRIVE LPi relies heavily on ensuring proper isolation. The bare board contains numerous exposed contacts, including a significant area of exposed live copper opposite the MOSFETs. This particular region serves to enhance thermal transfer for the inverter bridge. Establishing adequate electrical isolation for the board is imperative to prevent potentially hazardous short circuits. As a rule of thumb, there must be minimum 0.6mm air gap between exposed contacts and any conductive materials in the mounting assembly. All direct contacts to the unit, especially the thermal interface materials (TIM), must be electrically insulative. Keep-out zones for the microDRIVE LPi can be found in the CAD available from our datasheet.

The microDRIVE LPi board should not be placed under high stress and torsional loads. To appropriately compress the TIM between the motor controller and the cooling solution, the microDRIVE LPi should be mounted in a floating arrangement. This specific area to cool is identifiable by the presence of six MOSFETs on one side and the exposed copper thermal transfer pad on the opposing side. A backing plate that contacts the copper cooling surface (and has clearance for the surrounding electronics) should be used in conjunction with a compression plate on the MOSFET side to sandwich the microDRIVE LPi. See the diagram below for details.

The microDRIVE LPi is a bare-board motor controller with exposed electrical connections. Contact with water or significant amounts of dust/particulate can result in unit failure. Ensure that the microDRIVE LPi is mounted in a location with appropriate environmental protection to reflect the UAV’s operating conditions.

The following cooling considerations should be considered for the microDRIVE units.

The heat generating components on the microDRIVE LPi are highlighted in the below drawing.

The microDRIVE LPi has a particularly high power density, making effective cooling a challenge. To ensure the microDRIVE LPi can operate continuously at the required phase current, you need a cooling solution that can effectively dissipate the thermal power from the unit to ambient. It must do so while keeping the MOSFET's and the electrolytic capacitors within their operating temperature. To find power dissipation and temperature limit calculations, please consult our technical datasheet.