This webinar discusses high volume applications of electric motors between 10W-2HP that are used in appliances, tools, fans, pumps and other devices. It covers trends in energy efficiency, including more efficient motor types like permanent magnet brushless motors. The webinar also discusses loss mechanisms in motors and drives, electromagnetic torque production, desirable operation of AC machines, and control methods for brushless and induction motors. There is a question and answer session at the end where attendees can ask the speakers questions.

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 This webinar will be available afterwards at
www.eeworldonline.com & email
 Q&A at the end of the presentation
 Hashtag for this webinar: #EEwebinar
Before We Start

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Meet your Speakers
MODERATOR FEATURED SPEAKER
Dal Y. Ohm
President
Drivetech, Inc.
Aimee Kalnoskas
Moderator
EE World

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High Volume Applications of Electric Motors
 Application Examples
• Appliances & Kitchen Tools
• Residential Fans and Pumps
• Garage Power Tools
• Light Industrial Tools
• Lawn and Garden Tools
• Automotive…….
 Power: 10W – 2HP
 Power Source: Battery Pack, DC 5-50V, or 100/200VAC 1-Ph
4

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Trends in High Volume Motor Applications
 Energy Efficiency
• Induction Motor -> PM Brushless Motor (Rare-Earth)
• Gearless Direct Drive
• Higher Speed Motor
 Compact & Low-cost Design
• Box -> Combined Mechanical & Electrical Design
• Drive & Motor in One Package
• Large Scale Integration, Various Microcontrollers
• Effective Heat Removal

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Loss in Motors & Drives
• Efficiency  = Pout / Pin
• Copper Loss (I2R)
• Iron Loss (due to magnetic fields)
o Hysteresis & Eddy current Loss
• Mechanical Loss
o Friction, Windage, Fan, Mechanical translators
• Stray Loss (Other misc losses not defined above)
o Mostly due to slot and teeth flux pulsation harmonics
• Drive-related Loss
o Switching & Conduction Loss, Control Power, Fan
o Harmonics and PWM ripple
o Loss due to Non-Optimal Control

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Energy Efficiency
• Power Consumption in Industry - Motors & Drives account for > 2/3
• Overall operational cost ($)
o Installation cost
o Power Bill ( up to 10 times per year)
• Demand charges, Reactive power charges
o Maintenance cost and operating life
• Mandatory Regulation - Efficiency & Power Factor
• How to Improve?
o Consider Premium Efficiency Motor Types (PM)
o Control Methods

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Electromagnetic Torque Production
Cylindrical Machines Reluctance Machines
T = K Ms Mr sin rs T = K Ms2 sin(2rs)
S
N
NS
Ms
rs Ms
S
N
rs
Reaction Torque Reluctance Torque
Mr Mr

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DC and AC Machines
• DC Machines
o Magnetic Poles fixed in space (Stationary Flux)
o Requires Commutator and Brushes
• AC Machines
o Rotor and stator poles are rotating (Rotating Flux)
o PM Synchronous Motors, Reluctance Motors
o Induction Motors s = o + r
• Tendency to minimize electromagnetic energy
• For Consistent Torque Production,
o Consistent Angular relation and mmf magnitude
o Max torque at 90 deg.

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Rotating mmf in 3 phase system
• mmf = (Nse/2)[Ia cos  + Ib cos ( -120) + Ic cos ( +120 )
mmf = 1.5 (Nse/2)[Is cos (t - )]
• Constant magnitude, smooth rotation
o sinusoidal current & distributed mmf (winding, slots)
• All poly-phase windings produces sin. distributed mmf!!!
-50 0 50 100 150 200 250 300 350
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Flux Distaribution Waveform
N N
S S

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Desirable Operation of AC Machines
• Objective of Field Oriented Control (FOC)
o Current-generated Flux with rs = 90
o Consistent Flux magnitude
• Sinusoidal Flux Distribution
• When above conditions do not meet significantly?
o Direct IM – Starting, Transient
o Inverters – Transient
o Commutated Drives – Voltage mode, High speed
o Trapezoidal (6-Step) Control

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Drives for Various Motor Types
• Drive Functions
o Vary AC or DC Voltage Electronically to control Speed, or Torque
o Require Commutation for AC motors
• Open-loop
o DC motors (PM or Wound)
o Induction motors (Direct or Inverters)
• Closed-loop with Feedback for Commutation
o Brushless PM motors
o Induction motors with Field Oriented Control (FOC)
• Brushless PM motors - more efficient, compact, high speed!
• Performance of Drives affect efficiency!

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Power Circuit for Motor Drives
• 3 Phase Inverter Topology, Bidiretional
• Minimum # of Switches and Motor Wires
• Optional Regen circuit
DC bus +
DC bus -
AC Motor
R
Q1
Q2
Q3
Q4
Q7
C
Q5
Q6
Rectifier
AC

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.
Simple Control of Brushless PM Motors
• Add Commutation!
o 3 phase sinusoidal voltage (or current) based on rotor angle
o 6-step (trapezoidal) control for low-cost drives
o Feedback sensor (or sensorless) required
o Possible phase delay at high speed (T  current)
Td
Motor &
Load
AC PWM
AmplifierPI(D)
*

Position
sensor
Ke
+
-
V* V
Commu-
tation

s
e

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Trapezoidal vs Sinusoidal Control
• T  Iacos() + Ibcos(-120) + Iccos(+120)
• Zero ripple condition
cos2() + cos2(-120) + cos2(+120) = 1.5
• All harmonics contributes to loss (ripple & noise)
• Trapezoidal commutation for low-cost, low-power motors
o Wide angle conduction (> 120 )

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Current controlled AC drives
• AC current controller for
o Performs current control & commutation
o Multiple PI controllers
o higher bw (responsive), good performance at high speed
Iabc
Motor &
Load
PWM
AmplifierPI
*

Position
Detection
Ke
+
-
I*
Vabc
AC Current
Controller 
s
e


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Traditional Current Control
• Hysteresis Control (Fsw is controlled by error band)
• Linear Phase Current Control (Fpwm & PI regulator)
• Magnitude control
6-Step, No phase control
Vb*Commutation
Ia*
Vc*
Ic*
Va*
Ib*I*
+
+
+
-
-
-
--

PI
- V* Commu-
tation
I*
I
Vabc*

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Questions?
MODERATOR FEATURED SPEAKER
Dal Y. Ohm
President
Drivetech, Inc.
ohm@drivetechinc.com
Aimee Kalnoskas
Moderator
EE World
akalnoskas@wtwhmedia.com
@DW_Aimee

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 This webinar will be available at eeworldonline.com
& email
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