TON DUC THANG UNIVERSITY
FACULTY OF ELECTRICAL AND
ELECTRONICS ENGINEERING
401065
ELECTRIC MACHINES
CHAPTER 6
LOW POWER MOTORS
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CHAPTER 6: LOW POWER MOTORS
6.1. Single Phase Induction Motors
6.2. Series Universal Motors
6.3. Permanent Magnet DC Motors
6.4. Reluctance Motors
6.5. Stepper Motors
6.6. Brushless DC Motors
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OBJECTIVES
➢ Know some low power motor are widely
used in practical: one phase motor,
universal motor, reluctance motor, stepper
motor, brushless motor ect.…
➢ Remember the construction and working
principles
➢ Understand operational methods.
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6.1. SINGLE PHASE INDUCTON
MOTORS
Q: What would happen if there is only one
phase in the stator?  Pulsating MMF
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.1. Split Phase Motors
Split-phase motor:
(a) Connections
(b) Phasor diagram at starting
(c) Typical torque-speed characteristic
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.1. Split Phase Motors
Electronic Centrifugal Switches
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.2. Capacitor-Type Motors
Capacitor-Type Motors
(a) Connections
(b) Phasor diagram at starting
(c) Typical torque-speed characteristic
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.3. Permanent-split-capacitor motor
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.4. Two-capacitor motor
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6.1. SINGLE PHASE INDUCTON
MOTORS
6.1.5. Shaded-Pole Induction Motors
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6.2. SERIES UNIVERSAL
MOTORS
➢The universal (AC-DC) motor is a single-phase
commutated motor
➢This type of motor is identical in principle to the
DC series motor, but a few modifications have been
made to optimize the motor for AC use
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6.3. PERMANENT MAGNET DC
MOTORS
➢ Uses permanent magnets to provide the
stationary field poles.
➢ Power is applied only to the DC rotor (armature)
through a set of carbon brushes.
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6.4. RELUCTANCE MOTOR
6.4.1. Introduction
➢ A Reluctance Motor is a type of electric
motor that induces non-permanent magnetic
poles on the ferromagnetic rotor.
➢ Rotor does not have any windings.
➢ Torque is generated through the phenomenon
of magnetic reluctance.
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6.4. RELUCTANCE MOTOR
6.4.1. Introduction
➢ There are various types of reluctance motor:
▪ Synchronous reluctance motor
▪ Switched reluctance motor
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6.4. RELUCTANCE MOTOR
6.4.2. Synchronous reluctance motor
➢This is a simple of synchronous motor
➢ The rotor trend aligned with the rotation
magnetic field of the 3-phase stator winding
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6.4. RELUCTANCE MOTOR
6.4.3. Switched Reluctance Motor
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6.4. RELUCTANCE MOTOR
6.4.3. Switched Reluctance Motor
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6.4. RELUCTANCE MOTOR
6.4.3. Switched Reluctance Motor
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6.4. RELUCTANCE MOTOR
6.4.3. Switched Reluctance Motor
➢ Advantages:
▪ Simple construction- no brushes, commentator, or
permanent magnets, no Cu or Al in the rotor.
▪ High efficiency and reliability compared to
conventional AC or DC motors.
▪ High starting torque.
▪ Adaptable to very high ambient temperature.
▪ Low cost accurate speed control possible if volume
is high enough.
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6.4. RELUCTANCE MOTOR
6.4.3. Switched Reluctance Motor
➢ Disadvantages:
▪ Current versus torque is highly nonlinear
▪ Phase switching must be precise to minimize ripple
torque
▪ Phase current must be controlled to minimize ripple
torque
▪ Acoustic and electrical noise
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6.5. STEPPER MOTORS
➢ A stepper motor converts electrical pulses into
discrete mechanical movements.
➢ The shaft of a stepper motor rotates in discrete
step increments when electrical command pulses
are applied to it in the proper sequence
➢ Stepper Motor Types:
▪ Variable-reluctance
▪ Permanent-magnet
▪ Hybrid
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6.5. STEPPER MOTORS
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6.5. STEPPER MOTORS
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6.5. STEPPER MOTORS
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6.6. BRUSHLESS DC MOTORS
Brushless DC construction
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6.6. BRUSHLESS DC MOTORS
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6.6. BRUSHLESS DC MOTORS
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6.6. BRUSHLESS DC MOTORS
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SUMMARY AND ASSIGNMENT
➢ In this chapter, we have learnt:
▪ Construction and working principle of some
practical low power motors
▪ Applications
▪ Advantages and disadvantages
➢ ASSIGNMENT:
▪ Refer: [1]: 407-470; [5]: 271-282
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