On The Way to IE5 Motors:

Techniques to Improve Efficiency in

Electric Motors

Gustavo Luiz Simões Gorski Motors & Development Projects

Watt Drive - WEG Group Austria

Sebastião Lauro Nau Research and Technological Innovation WEG Equipamentos Elétricos – Motors

Brazil

Daniel Schmitz

Research and Technological Innovation WEG Equipamentos Elétricos – Motors

Brazil

Summary

1. Introduction

2. IE4 Efficiency Level

3. IE5 Efficiency Level 3.1 Application example

3.2 Payback Tool WEG

4. Efficiency over speed range

5. Techniques to Reduce Losses 5.1 Joule Losses in the stator winding

5.2 Joule Losses in the Rotor

5.3 Mechanical Losses

5.4 Iron Losses

5.5 Additional Losses

6. New Technologies for Super and Ultra Premium Efficient Motors 6.1 Permanent Magnet Motors

7. Conclusions

1. Introduction

1. How to increase the efficiency of an electric motor

with low impact on the cost and size?

2. How to reach IEC IE4 Efficiency Level with Induction Motor?

3. How to reach IEC IE5 Efficiency Level with PM Motor?

2. IE4 Efficiency Level

Compared to the efficiency level IE3,

the efficiency level IE4 motors have less

losses ranging from 10% to 24%.

IEC 60034-30 2nd Ed. will define efficiency

levels for motors from 0.12 to 800 kW, in

2, 4, 6 and 8 poles (for mains supply, fixed-

speed motors) and also for variable-speed

motors.

Efficiency levels according IEC 60034-30-1 Ed. 1.0 2014-03

3. IE5 Efficiency Level

• According to IEC 60034-30 1st Ed, IE4 efficiency motors have approximately 10% to 24%

less losses than the IE3 Efficiency level;

• Following an IEC recommendation to define IE5 efficiency level, WEG has considered this

pattern as well. It means WEG IE5 motors have around 20% less losses than its IE4

Motors.

Note: New IE5 efficiency level is already envisaged for a future edition of the standard.

Efficiency Level

[kW] IE4 IE5

7.5 92.7 94.2

75 96.1 97.0

Example – 4 Poles motor:

3.1 Application Example

Application example – Energy saving with high efficient motor

• A pump works 30 days/month, 20h/day, 12 months/year (7200 h/year) at approximately

1500RPM, according following duty:

• 30% of time at 100% load (30kW);

• 50% of time at 60% load (18kW);

• 20% of time at 15% load (4.5kW).

Chosen Motor

Motor Efficiency (%)

100% 60% 15%

1 Pump driven by IE3 93.6 93.1 84.8

2 Pump driven by IE4 94.9 94.1 84.2

3 Pump driven by IE5 96.0 95.8 94.2

Motor Energy Consumption (kWh/year)

146,475

144,841

142,020

IE3 IE4 IE5

3.2 Payback Tool WEG

Payback WEG available at: http://www.weg.net/institutional/AT/de/solutions/energy-efficiency/see-simulator

Available on App Store and

Google Play

Payback WEG –

Calculate your energy savings

4. Efficiency over the Speed Range Efficiency of Induction and PM Motors with the Frequency

5. Techniques to Reduce Losses

pj1 – Joule losses in the stator windings

pj2 – Joule losses in the rotor

pmech – Mechanical losses (friction and cooling system losses)

pfe – Iron losses

padd – Additional losses

pharm – Harmonics losses

Example:

The losses distribution for a WEG IE4 W22 induction motor of 30kW, 4 poles are:

pj1 pj2 pmech pfe padd pharm

43.7% 20.4% 3.53% 26.7% 4.91% 0.67%

5.1 Joule Losses in the stator winding

1) Enlarging the wire diameter maintaining the number of turns.

2) Enlarging the wire diameter reducing proportionally the number of turns.

3) Enlarging the stator length and the wire diameter, reducing the number of turns and

keeping the original stator slot size.

4) Just enlarging the stator length.

In practice, the adopted

solution usually is a mix of

enlarging the stator length,

reducing the number of

turns and increasing the wire diameter.

5.2 Joule Losses in the Rotor

Numeric model is already defined

Simulation time is still high: 72 h (36 cores)

Potentials:

Increase of the die casting capacity ;

Reduction of Aluminum;

Increase of quality - reduction of rotor porosity.

Numerical Simulation:

Time = 0,04 s Time = 0,18 s Time = 0,37 s

Rotor slots cast aluminum filling simulation

5.3 Mechanical Losses

Position of terminal box

Fan and fan cover – W22

Avoiding vortices

Smooth surface of non-drive end shield

Shape of the fan cover

Number of fan blades

Distance between fan cover and fan

Geometry of the fins

Vortices – W21 Vortices – W22

5.4 Iron Losses

Ways to reduce iron losses in induction motors:

1) Use of superior commercial grades of silicon steel lamination (usually thinner

lamination) increases dramatically the cost of the motor.

2) Reducing of magnetic flux density lamination cost increases by increasing

the amount of magnetic material, since the original motor performance must

not be affected.

3) Thermal treatment for steel lamination stress relief to recover the magnetic

properties along the border of the stator teeth, especially for those narrower

ones.

4) Use silicon steel lamination with high magnetic permeability at 1.5 T.

5) For a complete new stator design, it is important to search for the best stator

slot/tooth width ratio.

5.5 Additional Losses

14

Additional Losses of high frequency

due to Freq. x N2

Losses due to skin effect

in the stator

High frequency losses

(rotor bars)

Losses due to

interbar currents

Surface losses due to lamination,

burrs, and contact resistance

between lamination

6. New Technologies for

Super (IE4) or Ultra (IE5)

Premium Efficient Motors

6.1 PM MOTORS BLAC and BLDC Motors

PM BLAC (brushless ac) Motors or PMSM (Permanent

Magnet Synchronous Motors):

Similar to the windings of the induction motor

AC-sine wave drive with field-oriented control

Low torque ripple and acoustic noise

PM BLDC (brushless dc) Motors:

Usually has concentrated windings

DC-drive square wave switching stage

Typically used in low power applications

Distributed windings

Concentrated windings

6.1 PM MOTORS Motors with magnets on the surface

BLDC or BLAC

Windings distributed or concentrated

Rare earth magnets and ferrite

Manufacturing rotor easier

Low capacity field weakening (low inductance)

Usually without reluctance torque

Concern for retaining magnets at high speed

Distributed windings

Concentrated windings

6.1 PM MOTORS Motors with magnets inside

BLAC and BLDC motors

Most uses distributed windings

Rare earth magnets and ferrite

Increased ability to field weakening

Higher leakage flux

Reluctance torque

More difficult to manufacture than

the rotor with magnets on the surface

V magnets

Tangential magnets

Multi-layered magnets

Radial magnets

6.1 PM MOTORS LSPM Motor - WQuattro

LSPM – Line-Start Permanent Magnet

IE4 Motor

Hybrid motors: induction and permanent magnet (PM)

Start directly from the network: as induction motors

Synchronous speed operation: as PM motors

Efficiency equivalent to PM motors

Drawing of the stator and rotor

(merely illustrative)

IE5 OR, as a IE4 motor, BUT reducing at least 2 Frames per rating

New PM W22 Benefits

IE4

6.1 PM MOTORS – W22 Magnet

93% 94%

95,30%

IE3 IE4 IE5

15kW 1500rpm

[kW] W22 Magnet IE5 W22 Magnet IE4

15 160M 132S

18.5 160L 132S

22 180M 132M

30 200L 132M/L

37 200L 160M

45 225S/M 160L

55 250S/M 180M

75 280S/M 200M

90 280S/M 200L

110 315S/M 225S/M

132 315S/M 225S/M

160 315S/M 250S/M

FIRST IE5 Motor Line in the market

Completely interchangeable with W22 Induction Motor

Constant torque with the speed

Low noise levels

New PM W22 Benefits

6.1 PM MOTORS – W22 Magnet

Ref: Motor 55 kW,

2 poles

1980 Efficiency: 90%

1960 Efficiency: 88%

1990 Efficiency: 90,2%

2000 Efficiency: 93,6%

2012 Efficiency: 95,6%

2010 Efficiency: 95,1%

2013 PM IE5

Efficiency = 96,6%

74% Losses

Reduction

6.1 PM MOTORS – W22 Magnet

7. CONCLUSIONS

Which technology is the best, depends not only on the efficiency since other

characteristics like cost, size and weight, reliability, speed range, noise, vibration,

easiness of maintenance and general performance have to be also taken into

consideration.

Strictly in terms of efficiency, it is possible to say that PM motors have the best

performance because they do not have losses in the rotor and, therefore, exhibit much

better behavior at low frequencies for constant torque.

Nevertheless, induction motors, when properly designed and manufactured, can also

reach IE4 efficiency levels. Moreover, their performance can be improved at low

frequencies with constant torque by applying the Optimal Flux Solution.

THANK YOU!

Gustavo Luiz Simões Gorski

gustavosg@weg.net Motors & Development Projects

Sebastião Lauro Nau slnau@weg.net

Research and Technological Innovation – R&TI

Daniel Schmitz daniels1@weg.net

Research and Technological Innovation – R&TI