Dynamic Offset- and Drift Compensation in Powertrain Test Benches

One of the most important aspect of a powertrain test bench is to capture measurement data. To ensure the validity of the test procedures and the quality of the measurements it is essential to use regularly calibrated measurement systems. However, since these systems operate continuously and under rough environmental conditions such as a wide range of temperatures, vibrations and strong electromagnetic fields, it is not guaranteed that the captured measurement data is free of unwanted effects such as offset and drift. In this paper, a method to compensate for the unwanted effects on measurement data in powertrain test benches is developed and validated with real measurements on a powertrain test bench. This method uses symmetries in the type of measured data, for example drag losses in electric machines, to identify and calculate the offset while the test bench is running. It can be applied to various kinds of measurement systems such as torque sensors which usually rely on strain gauges for their operation, DC current transducers, DC voltage metering devices and more. It does not require an interruption of the test procedure and can be integrated into the test benches main control system to automatically and periodically execute the compensation routine for the specified measurement equipment. These factors make it a valuable tool to improve the accuracy, quality and consistency of measurement data on powertrain test benches.