Q&A with the experts: 30 years of motor & drive innovations

Feb. 18, 2017

In honor of our thirtieth anniversary, Processing is talking with experts on innovations over the last 30 years. Here we discuss with them motor and drive innovations.

This year, Processing magazine turns 30, and in honor of this, we have been talking to industry experts regarding the biggest innovations that have occurred since our magazine began. In this edition, we discus innovations in motors and drives with Tim Albers, director of marketing and product management for Nidec Motor Corporation; Michael Prater director of sales and marketing for TECO-Westinghouse Motor Company (TWMC); Ryan Maynus, application engineer for Siemens; and Mark W. Harshman, director of technical business development for Siemens.

What are your top 5 motor innovations during the last three decades?


Thirty years is a long time to talk about innovations.  Many changes have occurred in the motor industry over that time.  Five innovations that have occurred:

  1. Dramatic increase in the base efficiency of induction motors.  From small single-phase up to larger integral horsepower three-phase motors, the industry has dramatically changed to raise the basic efficiencies on most standard induction motors.  30 years ago, motor efficiency standards were just being created along with accepted test standards.  Now they are embedded into the fabric of the industry.
  2. The drastic reduction of cost and increase in reliability of variable frequency drives has driven the adoption of VFD’s on electric motors to all new levels.  That has brought about the addition of inverter wire to now be standard in the integral horsepower random wound motors and changes in electric motor designs and manufacturing techniques to deal with the VFD application across the industry as well as the capability to ground shafts to eliminate shaft currents.
  3. As a connected innovation to number two is the integration of VFDs with motors and controls in applications.
  4. Commercialization of motor technologies that have been around for a long time, but have not been broadly produced.  The growth and penetration of brushless permanent magnet motors in the last decade has become significant.  30 years ago, very small sales of non-induction motors or shunt wound or brush DC motors.   Now induction is still important, but brushless PM has grown dramatically and other technologies such as synchronous reluctance and switched reluctance have grown and now are starting to be found in more high volume applications.
  5. Harmonization of standards between Europe and NEMA (North America).  Though some differences still exist, particularly in mechanicals and starting current, most of the test standards and efficiency standards are now harmonized between the EU and North America.  That is a pretty big deal for worldwide consumers and manufacturers.
  6. Conversion of DC motors to mostly AC systems.  The increase in VFD capability has also led to a drastic decrease in DC motor application that is now mostly served in new applications and retrofits with AC motors and drives.


Likely the most revolutionary technology TWMC introduced was in 1985 with the World Series motor product line. It was hugely innovative for its time. Large motors back then were operating at efficiencies in the 80% and the World Series took those levels to the 90% range. Also, they were partially standardized, allowing for shorter lead times. From there, we’ve also developed our own smart motor device which will be marketed under Motor Health Management…more details will be coming soon about that and a similar innovative option for large synchronous motor control wheels. In the last 5 years, we also introduced the world’s first AC-DC hybrid propulsion motor. That was for the marine industry though. More is up our sleeve, but tbd!  Increase the motor’s efficiency also means that it will then have a higher inrush rating. When we began providing motors with higher efficiencies to customers that didn’t use them in the past, we saw an increase in phone calls related to breakers tripping on motor starters. They had been set for the lower inrushes so we saw a need to advise customers to increase their starter setting to accommodate the higher efficiency ratings.


  1. Standardized product
  2. Through the use of better processing tools – ie: computers, we were able to more accurately predict motor performance and reduce waste in the product. Example 3023 frame to 5010
  3. Optimized 2 Pole design to meet noise, vibration requirements of API while maintaining DR
  4. Improved airflow concepts along with optimized flux paths to increase power outputs by up to 40% in the same frame.
  5. Designed a product line to allow up to 6000rpm operation without using exotic components – ie: AMB, HIP rotor stiff shaft

In the last 30 years there have been many improvements and innovations made to induction motors.  Some of the most impactful ones Siemens has been a part of demonstrate our commitment to ingenuity which benefits our customer and our world.

Through the use of better processing tools like more powerful computers Siemens has been able to more accurately predict motor performance.  This change allowed for a more standardized product while reducing waste in the motor.  A stunning example is in the picture below.  Both motors are the same power, speed, voltage and enclosure, but as you can see, there is a big size difference.

Another example of innovation is the ability to optimize a 2 pole (3600rpm) motor design to meet stringent noise and vibration requirements.  For almost 40 years, Siemens has been successfully producing these motors.  Even 30 years later, induction motor users can struggle to find a quality and reliable motor to operate at a higher speed.

Improvements in airflow analysis and concepts along with better tools to understand motor flux paths have given way to better motor utilization which means more power in a given motor frame.  Siemens has been able to see as much as a 40% increase in power due to these improvements.

As we see more and more customers use variable frequency drives (VFD) to improve the process control, we have seen a need to operate motors beyond the usual 3600rpm speeds.  As a result, Siemens has developed a line of motors which can operate up to 6000rpm by using standard motor components.  In the past, to achieve speeds like this, many would have to introduce more exotic motor components like active magnetic bearings or special one piece solid shafts.  By using more standard components, it allows users to realize the benefit of higher speed and less equipment in the drive train while maintaining system reliability.

The last innovative motor concept I’d like to share is the development of a rigid shaft motor at a 2 pole speed.  One of the challenges with operating a larger horse powered motor at 3600rpm or at a speed range with a VFD is being able to meet the vibration requirements.  By introducing a rigid shaft motor that can achieve power ratings up to 8000HP, it allows user to maintain the benefit of an optimized power train system at a more affordable lifecycle cost.

Although Siemens has seen many unique and innovative motor designs, we are not satisfied.  We are truly living an Ingenuity for Life mantra every day as we strive to develop the next best motor for the industry and our customers.

What are your top 5 drive/VFD innovations during the last three decades?


  1. Reduction in size due to more efficient components
  2. Change from Darlington Power transistors with switching frequencies in the 800hz to 1,200hz to using IGBTs that now switch at mostly 2khz up to as much as 20khz.  That change has completely changed the dynamic of inverter application on motors.  Increased efficiency and reduced noise.
  3. The addition of standard communications protocols and basic processing as a standard part of a VFD is a big shift and innovation.  Some VFDs even serve as a PLC as a part of basic functionality.
  4. Extremely fast processing to allow for vector control of not just speed but also torque throughout a very wide speed range.  The increased motor performance based on the better algorithms and faster processing has really changed the constant torque market and accelerated the decline of DC.
  5. The ability of VFDs to control an induction motor, Synchronous reluctance of a brushless permanent magnet motor all with one set of hardware and only requiring software updates of configuration settings.


In the last 30 years, TWMC had limited experience in drives. Most of our technology was brand labeled until recently. The only innovation was regarding medium-voltage drives. Last year, TWMC introduced our first medium-voltage VFD. Developed here in Round Rock, TX from the ground up, it’s a modular VFD with liquid cooling that makes it highly versatile and flexible to use.


Variable Frequency Drives (VFDs) have existed since the late 1960s, and the development of the drives has closely tracked the development of power semiconductors.  Power diodes, and specifically thyristors (Silicon Controlled Rectifiers-SCR), initially provided the components for the first VFDs. However, the current-source drives generated harmonics requiring customers and VFD manufacturers to add various power components to mitigate the poor quality waveforms that disrupted both customer plant power and damaged their motors. Although they performed poorly, the current-source drives dominated the first decade of VFD history because of the limited availability of new power semiconductors.

But soon, the introduction of Darlington Transistors with sufficient power ratings allowed for the development of new CFD topologies and voltage source drives. Providers developed Field-Effect Transistors (FET), MOSFETS and eventually an array of new devices from GTOs IGCTs, IGBTs and many others, all with specific characteristics. The development of semiconductors focused on increasing the power capability and improving the efficiency of these devices by reducing their losses as well as increasing their switching speeds. Because of these advances, VFDs were developed with new drive technologies that were larger Hp (kW), more efficient, and had more power density.

The voltage source VFDs quickly displaced the older current source drives (LCI and CSI topologies), except in power ratings above 12MW. Unfortunately, these early drives caused motor damage and required the use of "inverter" grade motors. The inverter-grade motor had a larger frame to dissipate heat and higher insulation levels to tolerate the voltage characteristics of the early drives. The motor modifications added cost to the motor and made it difficult to retrofit a drive onto an existing motor.

In 1994, the first successful cascaded h-bridge VFD was designed using IGBT devices. The Robicon Perfect Harmony was a unique design that provided harmonic free waveforms both to the customer plant power grid and had an output voltage waveform that could be used by existing motors, no matter what their age. This breakthrough resulted in the establishment of the cascaded H-bridge design as the industry standard, which became the most copied design with the largest installed base of any VFD topology. Prior to 2000, it was believed that a 10,000Hp VFD could not be built using the latest IGBT devices. However, once the first unit was built and sold in early 2000, the door was opened for large voltage-source drives.

The top innovations and issues that have driven VFD/motor design over the last three decades include:

  1. The introduction of new power semiconductor devices which allowed for the development of Larger, medium-voltage VFDs (1960s to present). Present development around silicon-carbide and some of the Gallium Nitride materials is resulting in higher efficiency components thus increasing the efficiencies of the VFDs which is in line with DOE objectives of increasing efficiencies over the next 10 years by 30%.
  2. The oil crisis of the 1970s forced industry to look for ways to save energy costs and VFDs were identified as an excellent opportunity. This coincidentally corresponded to the semiconductor achievements in power ratings.
  3. The introduction of the first cell-based VFD in the Robicon Perfect Harmony in 1994 changed industry and resulted in the largest installed base of VFDs and the wide-spread use of VFDs in industrial applications.

Recently the DOE has begun funding on variable speed motors that combine the motor and drive into one package where the drive is integral to the motor. This is aimed at reducing footprint by 50% and decreasing costs. There are two possible approaches. The first is a new style of direct drive (e.g., matrix converters), which has never been commercially viable but may be small enough to be incorporated onto the motor frame. A second approach may be the development of variable reluctance motors which would utilize a very simple drive system and allow for easier single package integration. By 2030, VFD manufacturers who are still manufacturing stand-alone VFDs in cabinets may be competing with a single variable speed motor, especially in the power ranges below 1.5MW.

How have the DOE motor efficiency rules influenced the trend toward more efficiency in the process industries? Are industries/motor manufacturers handling the changeover well?


Before there were DOE rules, NEMA had already created motor efficiency standards.  Many of the process industries were in a slow adoption mode of the premium efficient products based on the economic benefits of motors that run a significant number of hours per year.  The DOE regulations in many cases follow what the process industries have already adopted.  So, the addition of DOE regulations in many cases had very little effect.  For example, the oil and gas industry and the pulp and paper industry have standardized on premium efficient induction motors that meet the DOE regulations, but almost 20 years in advance of the regulation.


We believe that the DOE has driven the trend…they are making the decisions and rules and motor mfrs have to comply. With that said, the changeover has been relatively easy on us. One of our faults is that TWMC has always developed a product that is more robust than it needs to be…which makes being cost competitive a challenge. So, when we had to increase efficiencies, most of our products were already there…just requiring a few tweaks in the design and new nameplates.


  1. Increased focus on system efficiency – pump, motor, drive, etc… together; focus on energy usage and utility penalties
  2. Industries are handling well, but manufacturers can struggle to meet.

That’s a great question.  Although energy costs have really impacted the need to develop more efficient induction motors, the DOE motor efficiency rules have influenced the industry as well.  In general there is an increased focus on system efficiency.  When a compressor has a drive train with a motor, drive and/or gearbox, the focus then becomes more directed towards a system efficiency as opposed to just a component efficiency.  Here is where a user can realize a true benefit. Understanding the impact on energy usage and utility penalties for a user also play a big role in embracing a more efficient motor and system.  In general, the industry is handling the rule well, but sometimes manufacturers can struggle as the change is more fully implemented.  Of course, at the end of the day, improving the motor and system efficiency is key.


Many customers are already demanding increased efficiency and smaller footprint in direct agreement to the DOE grant funding. These are currently addressed with new materials in the semiconductor devices and the increased power density in smaller packages. In a way, the development parallels the rapid advances in the computer industry — a 1000Hp VFD built in 1994 was 210 inches wide, while today that same 1000Hp drive is only 66 inches wide. In the coming years, we can expect that footprint to continue to shrink while the efficiency increases. Customer specifications already reflect these concerns and requirements. The customer processes now are built around VFDs as industry has accepted them as a valid process control method that saves cost.

The same situation exists in motors with the development of Permanent Magnet Machines (PMM) which are more efficient and much smaller than the conventional induction machine with the same power rating.

How has the increased use of VFDs in manufacturing systems and process plants changed how facilities operate? Have they increased the ability for process automation?


The addition of VFDs has changed and will continue to change how plants operate.  The VFD processor has more and more ability to take on some or most of the a local process control.  Also, many VFDs now have the ability to communicate, not just on custom protocols, but also even industrial Ethernet.  The ability to use VFDs to support or replace PLCs and increase communication is already available and will become even more embedded in standard practices in the next few years.


It’s allowed for overall system efficiency improvement. Adding a VFD to the system also corrects power factors which could lead to lower energy costs for the plant. Also, if they are using VFDs and PLCs, it can offer more control of the overall system and total process flow.


  1. Allows for better control of the process to eliminate waste in energy and what is being processed.  Also allows for longer life in equipment usage and improved reliability
  2. Yes – VFD controls working more directly with plant control room, etc.

In short, the answer is immensely.  VFDs change the picture completely.  They can reduce the use of a mechanical drive and increase system efficiency all while offering a smaller CO2 footprint.  Better control of the process helps eliminate energy and process waste.  This reduction also allows for a longer and more reliable motor life.  The introduction of a VFD can also increase the ability to use automation in the system.  Since a VFD can communicate and be controlled more easily by a plant control room, automation can be implemented when using a VFD.

If you had a crystal ball to see into the future, what do you think will be some of the top trends and innovations during the next 30 years?


More and more connected points.  We will have the ability to see and evaluate pretty much every process as well as the operational health and capability of the equipment itself.  Call it what you want, IIoT, IoT, Industry 4.0 or Connected factories, we will move beyond monitoring and controlling the process, to predicting process outcomes and predicting and scheduling equipment maintenance and repairs as opposed to reacting.  It is coming and will become commonplace in the next 10 years.  In 30 years it will be all that we know.

Continued growth in variable speed, integrated solutions and other induction technologies gaining a larger share of the market.  Synchronous reluctance, brushless permanent magnet and even switched reluctance motors will continue to take share based on higher efficiencies, low cost electronics and costs that will inch closer and closer to induction values.  Induction will not go away, but for higher operating hour applications, alternate technologies will take a larger and larger share.


We’ll definitely see a continuation of constant energy efficiency. We already see that DOE is pushing from IE3 to IE4…I guess we’ll stop short of 100% efficiency, since that’s impossible, but we’ll keep looking for innovations to make it possible. We believe we’ll see the trend continue to add more drives to plants and processes, also for efficiency’s sake and as the DOE begins to tighten efficiency requirements of the applications as well (compressors, fans, etc). We’re also seeing investments in Industry 4.0 or Smart Manufacturing that allows users to monitor process performance in real time.


  1. Higher Speed applications – building off VFD usage and goal to improve system efficiency, replacing mechanical drives
  2. Utilizing higher efficiency in larger motors – regulating like on LV, to offset swings in energy costs, low noise and reduce CO2 footprint
  3. Use of more permanent magnet motors
  4. Digitalization of motors – motors that are more connected to the manufacturer for better predictive maintenance, easier control locally, safer operation, less down time
  5. Smarter production facilities for motors – digital production/ smart factory
  6. Ability to use improvements in other industries to drive improvements in construction/testing of motors – ie: computers, networks, – tighter control of manufacturer to allow for better motor design
  7. Improved System Testing

As I look into my crystal ball, I see some exciting trends and innovations during the next 30 years.  As higher speed technologies improve, I see the industry building off the success of VFD usage to offer even better system efficiencies while maintaining higher speeds.  Improvements in active magnetic bearings technology will make it more affordable to offer high speed motor solutions like this more easily.

Governments around the world are interested in achieving higher component and system efficiency and I see this trend continuing.  As we know, the US DOE has already made law the efficiency requirements for low voltage motors.  I see this trend continuing into motors that go up to 2500HP and higher.  Regulating the efficiencies of even larger sized motors will allow a reduction in energy usage and a reduced global CO2 footprint.

Smart motors is another concept I see developing in the future.  What I mean by smart motor is a motor that can communicate more easily within and without the plant.  The ability for a motor to connect directly to a motor monitoring center to allow for predictive trouble shooting to increase the motor reliability while operating more safely with less down time.  With this improved communication capability, the plant will be able to communicate more easily with the motor as well.  With the introduction of a smart motor, the next step will be a digital production facility or a smart factory.

Just like computer advances helped improve motor designs in the past 30 years, I expect additional technology advances will drive advances as well.  Examples might be smaller, more portable computers, faster network connections, virtual reality and robotic technology.

The ability to complete system testing to improve and verify system efficiencies should also be an innovation in the future.  Today, only 1 or two components of the drive train are easily tested, but being able to test more of the drive train will improve the overall system efficiency and reduce the investment costs.


Siemens customers have requested increased efficiencies in order to save additional energy costs. A small efficiency improvement of only 0.2% can result in thousands of dollars in cost savings over the life of the product. Efficiency and footprint continue to be innovation drivers. In addition to these features, the addition of on-line diagnostics and monitoring aimed at increasing reliability will be another new design challenge over the next five years. Both power electronics and diagnostic control features are fairly well understood. One area that might be interesting is the cooling method for VFD power electronics. Currently, these are predominantly air-cooled, which creates a need for additional site costs and electric utility costs to run air-conditioning to keep the VFD cool. New technologies that eliminate the HVAC cooling costs are needed.

Motors and drives will continue to get smaller and have higher power densities. Their material and topology will change to meet the need for increased efficiency and smaller footprint. For motors and drives below 1.5MW, they will most likely be integrated into a single unit known as a variable speed motor.

On-line diagnostics and monitoring available 24/7 via iPhone and iPad will be the norm, and customers will expect to be notified by the motor or drive well before a failure occurs. The on-line capability may even include dispatching a service technician or sending replacement parts before the VFD or motor have failed.

Most VFDs have components such as transformers and reactors that utilize large quantities of copper, magnetic steel, and iron. These commodities have always increased in price and will continue for the foreseeable future. Only silicon-based components have come down in price over the last 30 years. The design and development of silicon-based transformers is underway and could be a breakthrough that further reduces the cost and footprint of VFDs.

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