About Invertek Drives
Reliability and efficiency determine the success or failure of a product in the industrial motor drive market.
These qualities have underpinned a record of year-on-year growth over the past 24 years at Invertek Drives, the manufacturer of variable frequency drives used to accurately control electric motors. Recent years have seen the development of enhanced research and development facilities at Invertek’s headquarters in Welshpool, UK, and the expansion of its global manufacturing facility. The company’s integration into Sumitomo Heavy Industries strengthened its capabilities for developing the next generation of variable frequency drive (VFD) technology, helping to increase the energy efficiency of electric motors and in turn reduce energy use and carbon emissions globally, and contributing to a more sustainable future for the planet.
Today, Invertek supplies motor control systems to customers in more than 80 countries, and its variable speed drives are used in a wide range of industrial and commercial applications: pumps, fans, heating, ventilation and air conditioning systems, elevators, cranes and conveyors. The motor drives support motor power loads ranging from 370W to 250kW – with plans to increase this to 500kW.
The company’s success in these markets has resulted in consistent annual 25% growth in sales of its Optidrive product range. This is due in large part to innovations in motor drive design, which produce more precise, efficient and reliable control of motors – as demonstrated in it being named a recipient of The King’s Award for Enterprise – the UK’s top business award.
As motor drive technology advances to provide efficiencies higher than 98%, it becomes harder and harder to optimize power performance. In its quest to achieve superior efficiency, Invertek depends on the insights into its products’ power performance that it can gain from the world’s most accurate power analyzer: the WT5000 from Yokogawa.
The Challenge
Background
The motor drive market has gone through a period of dramatic change. Efficiency regulations have incrementally been tightened, forcing operators of motorised equipment to replace fixed-speed electric motors with more efficient ones controlled by variable speed drives. At the same time, motor manufacturers have adopted new, more efficient motor topologies such as permanent magnet synchronous motors (PMSMs), brushless DC (BLDC) motors, and synchronous reluctance (SynRM) motors. While typical electric motor system efficiency in the second half of the 20th century was below 90%, today system efficiency commonly exceeds 95%.
The efficiency of the motor drive – the electrical circuit which controls the motor’s speed and provides the power input to the motor mechanism – is a crucial component of total motor system efficiency.
And while quality, reliability, ease of use and controllability are important factors affecting the customer’s choice of drive, efficiency is the most important determinant of a motor drive product’s success in the industrial and commercial markets.
The challenge
Invertek Drives’ R&D team has already achieved very high efficiency in its Optidrive range of products: this makes it hard to produce further incremental improvements.
When the challenge is to improve efficiency from 90% to 95%, uncertainty in the measurements of the power input and the power output – from which an efficiency calculation is derived – is relatively unimportant. Even an uncertainty factor as high as 0.1% would have a trivial impact on the system by comparison with the efficiency gains under consideration.
But the latest Optidrive products achieve efficiency higher than 98%. This means that the Invertek R&D team is working to achieve incremental improvements of a fraction of a percent. And this calls for an instrument which can measure and verify very small differences in efficiency, with a measurement uncertainty much smaller than the value being measured.
This requires extreme levels of accuracy and precision in power measurement.
[PREVIOUS CASE STUDY: This requirement can be met by a Yokogawa optical spectrum analyzer (OSA). Drawing on more than 40 years of experience in the optical test and measurement market, Yokogawa a broad OSA product range and offers industry-leading performance. This means that it can provide the OSA with the best match for Vexlum’s requirements.]
The Solution
Application requirements
The UK Innovation facility of Invertek Drives develops new Optidrive products for release to the global market. In the development process, it measures the power input to the drive, and the power output that the drive supplies to a motor, in order to calculate the efficiency of a new design.
The R&D engineers require a high level of confidence in the accuracy of the measurements: if measurement error is above a very low threshold, then the uncertainty in the measurement could invalidate any measured gain in efficiency.
Motor drives are also sensitive to disturbances in the power supply: harmonic analysis enables the system designer to measure the integrity of the motor drive power system.
Finally, Invertek requires a measurement solution that its customers trust, so that documented data on the efficiency of Optidrive products, and of competitors’ products submitted for benchmark testing, can be used as the basis for purchase decisions.
Invertek also uses a DL950 ScopeCorder to view the output from its inverters.
Measurement solution
Invertek’s chosen solution for power measurement of its Optidrive variable speed drives is the WT5000 Precision Power Analyzer from Yokogawa. The set-up of the WT5000 measurement system comprises two drive inputs and two drive outputs, along with a speed and torque input, facilitating precise measurement of the output at the shaft of a motor.
Invertek also uses a DL950 ScopeCorder to view the output from its inverters. The DL950 allows Invertek to analyse transient events: the modular DL950 has isolated inputs for easy connection of input modules, and captures signals with high resolution at high sampling speeds. It can log both electrical signals and measurements of physical parameters, alongside data sent over serial communication busses such as CAN.
For power measurement, the WT5000 offers such high accuracy that the development engineers can measure the very low levels of power loss found in Invertek’s ultra-efficient motor drive circuits. The measurement set-up enables Invertek to obtain accurate readings for motor, drive, and system efficiency.
The WT5000 also supports Invertek’s requirement for harmonic analysis: it can be used to evaluate and compare the input and output harmonics of motor drives up to the 500th order. Roman Lopez, Head of the Motor Control Department at Invertek, says: ‘The WT5000’s harmonics analysis capability is a key feature for us. It gives us a very good understanding of the input power at the drive – this insight allows us to improve both power integrity and output power efficiency.’
Results
WT5000: ultra-high accuracy helps Invertek break new ground in motor drive efficiency
Invertek Drives had been a long-time user of the earlier WT3000 Precision Power Analyzer. When the time came to add to the R&D laboratory’s test equipment, the newer WT5000 was the obvious choice because of its combination of ultra-high accuracy and a broad feature set for power measurement and power quality analysis.
According to Roman Lopez, the installation of the WT5000 has been popular with engineers at Invertek.
“Staff like the accuracy and reliability of the measurement results that they get from the WT5000. They also like user-friendly features such as the out-of-the-box software solution, responsive touchscreen, and intuitive menu of options for operating the instrument.”
Roman Lopez, Head of the Motor Control Department at Invertek
Supported by its use of the WT5000 and the DL950 ScopeCorder, Invertek is improving the energy efficiency of its products to unprecedented levels, providing a valuable contribution to global efforts to reduce carbon emissions from industrial equipment. It is fitting that Invertek’s advances in energy efficiency have been made through the use of Yokogawa instruments, since Yokogawa is itself strongly committed to environmental action, including a plan to achieve net-zero emissions.
Thus the precision and accuracy of the WT5000 and the DL950 not only help Invertek to optimize efficiency and reduce energy losses, but also contribute to a more sustainable future.
WT5000 Precision Power Analyzer
Precision at your fingertips
The WT5000 is the world’s most accurate precision power analyser that guarantees a basic power accuracy of ±0.03%. Operable by touch and hardware, the WT5000 offers an intuitive measurement experience for applications such as automotive development, efficiency tests of inverter-driven motors, renewable energy technologies and traction applications like pumps and fans. Define and use event triggers and custom computations to suit your application needs and view measurements in numeric, waveform, bar, vector or trend formats.
The benefits of the AQ6370E include:
Insights from up to 7 swappable input elements:
Make simultaneous measurements on up to 7 inputs and compare them in split screen mode on the high-resolution 10.1” touchscreen. The modular architecture of the WT5000 features 7 slots for users to swap between different types of input elements, allowing you to expand or reconfigure the WT5000 as your applications and their needs change.
Evaluate up to 4 motors simultaneously:
The motor evaluation function enables measurements of rotation speed and direction, synchronous speed, slip, torque, mechanical power, electrical angle and motor efficiency from the analog or pulse outputs of torque sensors or pulse outputs of rotation sensors. A single WT5000 can be configured for measurements of up to 4 different motors simultaneously using torque and rotation sensors.
