Essentially, a vehicle’s powertrain is the system that powers the car – traditionally a combustion engine – and transfers that power to the transmission, drive shaft and finally to the wheels of the car. Electrification of the powertrain is shaping the future of developments in vehicle technology – along with influence from sustainable energy drivers to push high fuel efficiency or to be compliant with relevant CO² emission legislation. In addition, key technology drivers are now focusing on improved drivability along with newly applied techniques such as inverter technologies to power the electric motor or used to charge the battery as a result of regenerative breaking. Within the development process of any part of the powertrain, a combination of electrical signals and physical parameters related to mechanical performance needs to be measured as part of a complete test cycle. The electrical signals are coming from the power electronics linked to the high-voltage battery and inverter, while the physical parameters are found in the process of electrical to mechanical conversion. To obtain a total understanding of the overall system performance, measurements have to be taken on the electromagnetic power converter and the power electronics, along with data from the powertrain management system operating over a vehicle serial bus network like CAN. Moreover, these tests have to be carried out simultaneously to arrive at an overall optimum solution, rather than optimizing single components individually.
Traditionally, data recorders or data-acquisition systems with sample rates of up to 10,000 samples per second have been used to measure the electrical and physical parameters in the automotive area. Such systems normally offer a high channel count, which enables the user to combine several sensor outputs and isolated input channels to measure the electrical system – often involving floating voltage levels – as well as physical parameters such as temperature, vibration and stress on materials.
ScopeCorder vehicle edition
Trends in development of electric mobility has led to the increased usage of power inverters, and because of the higher frequencies and higher voltage involved in these devices there is now a demand for isolated measurements of speeds of up to 100 million samples per second (100 MS/s). These sample rates are traditionally offered by oscilloscopes in combination with differential probes, enabling by oscilloscopes in combination with differential probes, enabling an engineer to watch transients of voltages and currents that appear at higher frequencies. A further area of interest is the powertrain management system, operating over a vehicle serial bus like a CAN network and continuously transmitting engine performance parameters such as engine temperature, rotation speeds and pressure levels. Together, these areas present a considerable measurement challenge in bringing electrical signals, physical performance parameters and data from the powertrain management system together in a single measurement. In order to reduce the time and effort required to combine these multiple parameter recordings, Yokogawa has developed the DL850V ScopeCorder Vehicle Edition: an instrument that combines the benefits of a high-speed oscilloscope with those of a traditional data acquisition recorder in a single, portable package. A ScopeCorder can capture and analyze transient events which may last only microseconds, but is also able to carry out complete powertrain endurance tests over periods of up to 30 days.
The instrument offers channel isolation, signal conditioning, and high channel counts. The new DL850V Vehicle Edition also incorporates a CAN and LIN bus monitoring function, allowing the user to decode the CAN or LIN signal and monitor the transmitted physical data such as engine temperature, wheel speed, acceleration and pressure. These values can then be compared with the data coming from real analog sensors. By combining multiple high-voltage and current signals (sampled at up to 100 MS/s) with physical parameter measurements like temperature, pressure or vibration in combination with the decoded CAN bus signal, a single measurement file is created on the DL850V – see Figure 1. This results in a great deal of time and effort saved in analyzing the whole system compared to other approaches where measurement files from multiple measurement instruments have to be combined before analyses can be done on a PC.
Figure 1: A single measurement file is created on the DL850V by combining multiple high voltage and current signals with physical parameter measurements and the decoded CAN bus signal.