Direct Calorimetric Test Bench for Power Drive Systems with Power Losses up to 20 kW

A direct calorimetric test bench is presented, designed to test drives, motors and gearboxes with power losses up to 20 kW and a mechanical output power of 150 kW, up to 6000 rpm. The calorimeter setup is a direct type; therefore, it determines the power losses of a device under test (DUT) by measuring the coolant temperatures and flow rate. This type of measurement achieves an uncertainty below 1% on the power loss determination. The construction of the test bench, the required measurement equipment, the measurement procedure and especially measurement uncertainties and results are described in detail. The test case results of a measurement campaign with an electric axle drive, consisting of a liquid-cooled inverter, liquid-cooled high-speed permanent magnet synchronous motor and integrated slip-controlled clutch and gearbox, are presented. The calorimetric setup reaches an uncertainty of ±0.7% or ±25.9 W on the power loss at 25 kW mechanical output power.