DRIVES, CONTROLS & MOTORS FEATURE
Getting beyond numerical results for testing electric and hybrid drive trains
Since significant efforts are now focused on more efficient electrical machines and drives, evaluating motor efficiency has become extremely important. The main issue, however, is how to implement an accelerated procedure that obtains the motor or drive efficiency for all operating points safely, accurately and rapidly. Ordinary test methods only offer inadequate numerical results. Here, HBM discusses how to get beyond numerical results
analysis. Finally, verification of results is not possible because no raw data is available, requiring retesting if anything is in question. As a result, one needs to make several assumptions about issues and errors; make changes based on those assumptions and then retest, which is time consuming and rather costly. With the eDrive Testing solution, HBM has
T
o get beyond numerical results, all electrical, mechanical and physical signals
must be acquired simultaneously at high sample rates, coupled with advanced real- time custom analysis and fast data transfer to automation systems, making it possible to perform electric motor and drive efficiency mapping accurately and rapidly, as well as almost any type of advanced analysis. Electrical drives are used in a wide variety of
applications, basically every electrical machine that is inverter driven or contains a variable speed drive. The key is to design and test for the maximum efficiency at all operating points in the entire drive train safely, accurately and rapidly. Traditionally, signals along the drive train are measured with a wide range of measurement systems. For example, digital multimeters are used for battery voltage and current measurements and traditional power analysers for measuring the output of the inverter. Sometimes a scope is used to view the signals. To measure machine output, a torque sensor and some type of data acquisition system is used. Unfortunately, there are several issues with
this traditional setup. Firstly, there is no time synchronisation between all the measurement systems; therefore, it is difficult or nearly impossible to make comparisons between mechanical (torque/speed) and electrical (voltage/current) signals at the same point in time. Also, no raw data is available and so no advanced analysis can be performed. Typical power analysers only offer a few calculations per second, not enough for feedback on automation/control systems. As well as this, power meters are not reliable during dynamic load changes, start up or any changes in speed, an area that needs further testing and
introduced a revolutionary tool that overcomes the limitations of the typical test method using a high-speed data acquisition power analyser. The benefits include: • Synchronous recording of all drive train
signals, so mechanical and electrical traces can be compared accurately plus easily configurable to test 3, 6 or 12 phase machines and acquire more signals like CAN, temperature, vibration and strain.
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Real-time advanced analysis like motor mapping, dq0 (Park) and Space Vector (Clarke) transformation enables immediate results rather than hours or days. • The transfer of real-time calculated results to automation systems via EtherCAT at 1,000 results per second. • Perform real-time power calculations per half cycle with a typical 0.02 per cent power accuracy, even during dynamic load changes, start up or any changes in speed. • It is possible to perform verification of
results any time as raw data is available. No retesting is needed if anything is in question. HBM’s new efficiency testing method identifies a revolutionary tool offering significant savings in time and cost, while greatly accelerating the ability to analyse electrical motors, inverters and drive trains with any type of rapid analysis, in a matter of seconds rather than hours or days. As a result, this makes it possible to clear the way for even more efficient electric motors, inverters and drive trains at a rapid rate. This boosts productivity, capability, and research and development White papers on the topic ‘Analysis of
electrical inverters and machines’ are available to download via the website below.
HBM T: 0208 515 6000
www.hbm.com/power analyzers
ANGLIAN WATER CUTS £2,000 A YEAR FROM BOREHOLE PUMP COSTS
Anglian Water is saving £2,000 a year on a borehole pump’s electricity costs following the installation of an ABB variable speed drive (VSD) on a submersible pump motor. The £7,000 project investment is expected to pay for itself within three and a half years. The borehole is one of two operated by
Anglian Water that feed the reservoir serving customers in Sudbury, Suffolk. Prior to fitting the VSD at Blackhouse Lane, both pumps were run at fixed speed all of the time but had to be turned off frequently as the reservoir had reached the desired capacity. Anglian Water suspected that this system was inefficient as it was pumping more water than was required. The frequent stopping and starting of the pumps was also causing excess turbidity in the extracted water. Following an assessment by Gibbons
Engineering Group, the decision was taken to install a VSD on the pump motor. The drive alters the speed of the pump’s motor to top up the reservoir as required. The borehole pump at Woodhall Road, without a VSD, runs at full speed to provide most of the demand. Gibbons recommended a 132kW ABB drive. The VSD receives a 4 20mA signal via a radio link from the reservoir’s level transducer. If the signal is less than 16 mA, the pump motor runs at maximum speed, while a signal of greater than 16.8mA means that the pump motor runs at minimum speed in a range of 40-50Hz. This has reduced the amount of energy used by the pump motor at Blackhouse Lane, resulting in the £2,000 annual saving. It has also solved the problem of turbidity levels in the extracted water, which is now within acceptable levels. The new arrangement has also built redundancy into the system, improving reliability.
www.abb.co.uk
DESIGN SOLUTIONS | OCTOBER 2017 29
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