Software turns oscilloscope into power measurement platform

September 29, 2014 // By Christoph Hammerschmidt
For developers active in the field of electric drive technology Teledyne LeCroy has developed the three-phase Motor Drive Power Analyser software that runs on its recently introduced eight-channel HDO8000 oscilloscope. The combination of oscilloscope and software renders a complete platform for developing and debugging embedded motor control systems and related power sections.

Comprising measurement and test options for three-phase power electronics, analog and digital sensors for motor and related mechanics as well as embedded controls, the system enables designers and developers of motors, motor drives, variable frequency drives, industrial automation and motion control equipment manufacturers to integrate electric drives with related control electronics, validate systems and perform similar tasks. Unlike available solutions, the HDO8000, combined with the associated software, can even measure drive power and efficiency, making power analysers hitherto used for this purpose redundant.

The combo of software and oscilloscope also permits the capture of waveforms from the driver power section, power transistors and embedded control systems. Thus, the platform covers all relevant aspects of drive analysis and debugging.

A graphical user interface guides the user through the setup and connection procedure. The setup capability includes both two and three wattmeter calculation methods with line-line and line-neutral voltage conversion.

The Motor Drive Power Analyser software supports almost all available types of speed, rotation or position sensor, including analog and digital tachometers, resolvers BLDC Hall sensors, Quadrature Encoder Interfaces (QEI). In addition signals from Hall sensors and QEI signals can be integrated through digital inputs, preserving analog input channels for other signals.

The system computes a broad range of parameters related to power (real, apparent, reactive), voltage, current, phase angle, power factor and efficiency based on voltage and current waveforms. The results are displayed in a user-configurable table which is displayed on the screen along with the associated waveforms. Such information normally requires a power analyser.

The HDO8000's long acquisition memory of up to 250 Mpts per channel provides unique capabilities for motor and drive dynamic response analysis. For example, 25 seconds of continuous acquisition capture is possible at a sample rate of 10 MS/s. This permits understanding of dynamic drive behaviours, such as startup, application of load, or fast changing load conditions, and correlation of drive response problems to control system