High-performance motor designs
Motor innovations: Advanced motor technologies influence motor form factors, performance, and efficiencies. Examine how these technology advances can help with your next set of applications.
Why is it possible to design a higher performance motor and drive today? The answer appears to be better design software continuing to be improved on an average of once per year. It’s now possible to design very complicated motors that enhance torque, power, efficiency and power factor. This was more difficult 10 years ago.
Software’s sophistication has significantly improved for motor designs and drive and control designs.
Motor innovations, four areas
Four areas of motor innovations follow.
- Thepermanent magnet (PM) motor remains a favorite, assuming the application can live with the high cost of the rare earth magnets.
- Thesynchronousreluctance motor is significant because of improvements made in the drive and control topology. Two European-based automation companies, Siemens and ABB, are beginning to design 60 Hz versions, but we likely have a couple of years before the full product line will be available.
- Switchedreluctance (SR) motor technology is a close third. For custom application requirements they can exceed synchronous reluctance in capabilities.
- Theinduction motor drops to fourth position on the innovation scale, largely because it is protected by immense tooling and manufacturing investments already paid by various motor suppliers. Because of invested assets and market share, motor–drive companies building to requirements from National Electrical Manufacturers Association (NEMA) often seem to adopt an “If it isn’t broke, don’t fix it” approach to motor design and innovation. It would seem many will change only when they are forced to by market requirements for increased performance.
Others (1-3) will require more tooling investments and higher rates of production to reach more applications at lower-than-current costs.
Some motor innovation highlights follow.
SR motors, application
While other motor types can use an inverter (variable frequency drive), the SR motor must have a completely separate drive. This motor tends to be custom because the user needs a full motor-drive system. It is dedicated to an application or set of applications. It usually is not found on the internet until the application goes into production.
SR Drives in the U.K., part of US Motors and Nidec Corp., is a switched reluctance–motor that can provide very high performance, with as much as a 10% efficiency increase compared to ac vector motor.
Linear Labs describes use of its SR motor in a direct–drive electric vehicle application. It describes an in-hub automotive drive design where two or four motors can create a competitor to a centralized electric drive motor. The Linear Lab motor operates in rotary and linear fashion and the company claims ability to do twice the torque and power of any existing motor to date.
The design has some major advantages, including lighter weight, better range and less maintenance. Power factor is a disadvantage in this design, and is usually about 10% lower.
A recent new version is the PM assisted synchronous reluctance (PM aSyRN) motor, with ferrite magnets added to the rotor structure that improves torque, power and power factor.
Another application that motor–drive innovators are targeting is the all-electric aircraft.
Rolls-Royce has noted the need for development of better liquid fuels to keep up with the expected advancements in electric motors. Siemens, identified as the motor supplier for this application, hasn’t referenced on a website use of its motor-drive technology for small-aircraft high–speed high–power propeller motor drive.
The Rolls-Royce engine also requires a turbine engine for commercial aircraft. It is possible to build small all-electric aircraft motor–drives, and commercial turbine-electric engines seem likely within a decade.
The synchronous reluctance motor works better at lower loads (50%) than induction motors and PM motors.
Synchronous reluctance motors work over a wider speed range.
High-performance motors can be hybrid designs. The highest performance torque density motor to date appears to be the Mercedes Benz i3 traction motor. The rotor structure is combines surface and buried magnet in a complicate pattern.
Other innovative motor products
A sampling of innovative motor products in the New Products for Engineers Database follows. See more at www.controleng.com/NPE.
Baldor-Reliance EC Titanium Integrated Motor Drive from ABB Motors and Mechanical Inc.: EC Titanium motors are a highly efficient integrated motor drive that combines synchronous reluctance and permanent magnet technologies for a sustainable, wirelessly connected solution that improves customers bottom line. It has IE5 efficiency and is highly efficient at full load and partial load conditions offering up to 16% efficiency gains at partial load and speed. The integrated product saves control panel space and reduces wiring costs by placing the drive on top of or on the opposite drive end of the motor. It has tune and control flexibility with multiple options including wired keypads and PC tools for easy commissioning and tuning as well as Bluetooth communication for easy configuration and ABB Ability connectivity for health monitoring. Reliable and low noise has very low starting current and less cogging reduces mechanical stresses of the driven load.
Note of comparison: If one plots a torque vs. speed curve for the induction motor and synchronous reluctance motor (SynR) with the same horse power levels, the SynR motor immediately develops more torque than its induction partner. This is due to internal motor losses and synchronous operation. By 10% load point on the motors’ torque-speed plot, more torque leads to more output power (TxN) and efficiency (Pout/Pin). The SynR motor holds this advantage until 75% motor load is achieved where they become equal. The SynR motors also can reach higher IE efficiency levels.
PowerPlus Stepper Motors from Moons’ Industries serve as high-torque direct replacements for NEMA 23, 24 and 34 frame motors from Applied Motion: PowerPlus Hybrid Stepper Motors from Moons’ Industries eliminate the hassles of resizing motors by providing 25% to 40% more torque across the entire speed range of a motor. With the same physical dimensions as standard NEMA 23, 24 and 34 stepper motors, the motors can be dropped into place to minimize upgrade costs while improving performance.
ATO 400 W Brushless DC Motor with Controller/BLDC Motor Kit from ATO Inc.: High quality brushless dc (BLDC) motor kit includes a 24-V brushless dc motor with 400 W power, 3,000 rpm high speed, 1.3 Nm holding torque, and high efficiency motor controller for electric car applications. With small size, high reduction ratio, low rotation speed, high torque and little noise, they are widely used for unmanned aerial vehicle, medical equipment, industrial equipment, electrical tools and mini household appliances.
The BLDC motor controller provides:
- Fault detection and protection. It can identify faults via LED twinkling code.
- Battery voltage real-time monitoring. It will stop work when battery voltage is too high or too low.
- Built in current detection and over current protection.
- 5-V sensor power supply support.
- 12-V brake signal input configurability.
- 3-phase Hall position sensor input, open collector output and the controller provides pull-up resistor.
Premium-Efficiency, Cast-Iron Three-Phase AC Motors from AutomationDirect: The motors meet the requirements of the Energy Independence and Security Act of 2007. The MTCP2 Series has a low cost of entry to provide a quicker payback on investment and are available in 1,200, 1,800 and 3,600 rpm. They have totally enclosed fan cooled (TEFC) enclosure, and designs are NEMA TC-frame (C-face) and T-frame motors (C-face kits available for motors over 30 hp). NSK/NTN/SKF brand premium quality ball (1-75 hp) or roller bearings (100-300 hp), with maintenance free bearings for 10 hp and below. They have V-ring shaft seals on drive end and on opposite drive end, are electrically reversible and have Class F winding insulation. Service factor is 1.25 (1 to 200 hp), 1.15 (250 to 300 hp), 1.0 with ac drive (all). They meet or exceed Premium Efficiency standards and are Class I, Div. 2 for hazardous location use.
High Torque Motors from Baumueller-Nuermont Corp.: With a torque of up to 80,000 Nm, the DST range meets the highest demands in direct- drive technology with very smooth–running characteristics and high torque at low velocities. Energy-efficiency is maintained through wide speed/load range with low-noise. It has water cooling in a stainless-steel design and a smooth housing surface – easy to keep clean. Permanent field high-torque motors include IP54 type of protection and is suitable for sophisticated direct drive technology.
Direct Drive Motors from ETM Electric Torque Machines: These apply at all speeds including very high speeds, but are particularly useful 1,000 rpm. For any application in this range that requires high continuous torque, this offers lowest total cost, smallest size and weight, best efficiency, and highest reliability. As a result of our ultra-high continuous torque and broad operating performance window, ETM’s technology is eliminates the need for gearboxes in a drive system and reduce the number of motor and gearbox combinations used for a product line. Motors deliver continuous torque from 5 to 200 Nm (40 to 1,800 lb–in). However, motor size is scalable up or down for the right applications.
Linear Induction Motor from H2W Technologies Inc.: The LMAA-04-01 Linear Induction Motor can generate 10.6 lb [47 N] at a 15% duty cycle. It was designed for high speed operation and also can be operated at stall (zero speed) to produce static thrust. Typical applications include conveying systems, baggage handling, personal rapid transport systems, theme park rides, and active linear braking systems.A Flat Motor for High Torque from maxon: The EC 90 flat has a diameter of 90 mm and is available in two versions, with 160 or 260 W of power. In the 260 W version, the motor delivers a continuous torque of up to 1 Nm, which makes it the most powerful among all drives, without a gearhead. Possible applications include wheel drives, logistics systems and pumps. With an encoder, this brushless dc motor is ideal for positioning tasks.
Linear Shaft Motor from Nippon Pulse America Inc.: The L250SSS Linear Shaft Motor is a 25-mm diameter linear servo motor with a single winding and a small forcer, just 30–mm long, and with higher force than competing off-the-shelf motors. Its maximum usable stroke reaches to more than 2 m in length. The motors are available in 25–, 32– and 35–mm shaft diameter sizes, and with single, double, triple and quadruple winding options. The L250SSS and the other motors in the SS series are ideal for life sciences and industrial applications in which multiple forcers are required to travel along one shaft.
Brushless Servo Motors from Orbex Group: These brushless servo motors combine high torque, low inertia and various customizable options to improve efficiency in dynamic servo-driven applications. Available in a range of frame sizes (60 to 176 mm), NdFeB-based brushless servo motors include incremental encoders for position feedback and electrical commutation—enhancing motor efficiency, minimizing maintenance requirements and increasing throughput. Customizable windings make it easy to meet technical requirements. Integrated gear reducers reduce package size and lower overall costs. Other customizable features are available. The motors offer smooth, low-cogging motion and IP65-level protection for reliable operation in demanding industrial or outdoor environments. Typical applications include communications, security and AGVs, defense, packaging, robotics and others.
PMX Series Stepper Motor from Kollmorgen: The stepper motors were redesigned with versatility, ease-of-use, and cost effectiveness in mind. They provide high torque in a small package and come in a wide range of standard sizes, constructions, windings and options. The high-performance, brushless, maintenance-free stepper motors provide very precise, extremely cost-effective motion control. These hybrid stepper motors inherently move in small, very precise, 0.9, or 1.8–degree increments (400 or 200 steps/revolution). Added features include custom leads, shafts and connectors. Motor frame sizes include NEMA 08, 11, 14, 17, 23 and 34.
UlteMAX Axial PM Motor from Regal Beloit America Inc.: This permanent magnet motor is a continuous duty axial motor. Models are 3 to 5 hp (187XW), 7.5 to 10 hp (186XW) and 15 hp (206XW). They have three-phase/460 V/60 Hz integrated DPT control with variable torque loads. The 3–5 hp motor is designed to be scalable to 230 V, three-phase/60 Hz applications. The motor offers a new way to look at the design of HVAC and other thermal air moving systems with a thin 5.5–inch width. Weight is less than half the weight of a conventional radial motor. It is more compact and has a mountable motor. It is designed to be used with plenum fans with speed ranges from 500 to 5,200 rpm. In this application, the plenum fan wheel mounts directly to the motor rotor hub (versus a traditional radial motor’s shaft, belt and sheave packaging). This eliminates the need for the additional equipment, its associated maintenance and potential for efficiency reduction. In addition, the motor’s profile has been optimized for air movement, allowing operation at higher temperatures with greater reliability.
Allen-Bradley Kinetix VPC Servo Motors from Rockwell Automation: These Kinetix Servo Motors provide smooth, integrated motion control over EtherNet/IP networks. Kinetix VPC Continuous Duty Servo Motors are optimized to run on Kinetix 5700 Servo Drives, providing continuous power and torque. Kinetix VPL Low Inertia Servo Motors and Kinetix VPF Food Grade Servo Motors operate with Kinetix 5500 and 5700 Servo Drives and deliver high dynamic performance.
Limited Angle Torque (LAT) Motor from Sensata: BEI Kimco model LAT22-18 is for motorized valve control. The low cost, direct drive motor can be integrated into a valve assembly for thermostat control as well as fuel metering, air intake shut off, fuel shut off, or air start control applications. Measuring just 2.2-in. diameter by 1.8-in. length, the motor features an encapsulated coil assembly to withstand the harsh chemical environment of the application. The coil assembly includes threaded mounting holes for easy installation into the valve assembly. The desired size and weight requirements were achieved by attaching permanent magnets directly to the butterfly valve shaft. The keys to the motor’s design are torque capabilities greater than 50 oz-in over an excursion angle of 90 degrees, operating temperature ranges from ambient to 257°F (125°C) and compact size. Direct–drive motors eliminate gear boxes or other mechanical linkages that can break and wear, offering higher reliability and less maintenance. LATs are single phase so are simple to control and install.
Simotics MV449 AboveNEMA Motor from Siemens Industry Inc.: Siemens MV449 Above–NEMA motor has an industry leading 350 hp at a Class B temperature rise and 400 hp at a Class F temperature rise. The motor has more than 14% more power compared to other frames in the market and is also up to 49% smaller compared to the previously offered 500 frame. Less space means better plant layout utilization. Compared to a typical motor of this size, this adds 0.4% efficiency on average. Being able to offer up to 1.5% more efficiency allows users to save more money on energy, reduce the carbon footprint and realize greater return on investment (ROI).
Dan Jones is president, Incremotion Associates, and Mark T. Hoske is content manager, Control Engineering, CFE Media, firstname.lastname@example.org, with a technical read by Frank J. Bartos, Control Engineering executive editor, retired.
KEYWORDS: High-performance motors, motor design
Permanent magnet, synchronous reluctance motors are leading in innovations.
Switched reluctance motors is a close third, and induction motors are running fourth.
Sampling of motor innovations are offered from the New Products for Engineers Database.
What motor innovations will enable your next application innovation?