Mechatronics

1. Raya University
Collage of Engineering and Technology
Department of Mechanical Eng.
Course name: Introduction to Mechatronics
Target Group: Regular ME 5th year Students
Prepared by Gebeya T.(M.Sc. In Mechatronics and Robotics Eng.)

2. Chapter 3.
Semiconductor Devices and motor Controlling
3.1 Introduction
What is semiconductor? motor control system?
Semiconductor device is electronic circuit component made from a material that is
neither a good conductor nor a good insulator.
Motor Control system is system of motor control to convert and regulate electrical
power in to desired output.
What is the relation ship between semiconductors and motor control systems?
Semiconductors play a critical role in motor control systems by providing the necessary
electronic components for:
power conversion,
control, and
switching.

3. They enable the efficient and precise control of electric motors, allowing for
improved performance, energy efficiency, and functionality.
a few key aspects of the relationship between semiconductors and motor control are:
Power Electronics
Motor Drive Circuits
Pulse Width Modulation (PWM)
Sensing and Feedback
Overall, semiconductors provide the necessary electronic components and control
techniques for efficient and effective motor control.
They enable precise power conversion, motor drive control, and feedback
mechanisms, leading to enhanced motor performance, energy efficiency, and
automation capabilities.

4.  Power Electronics:
Semiconductors, particularly power semiconductor devices like transistors and
thyristors, are used in motor control to convert and regulate electrical power.
They handle high voltages and currents, switching power on and off to control the
flow of electricity to the motor.
 Power semiconductor devices such as insulated gate bipolar transistors (IGBTs)
and MOSFETs are commonly utilized in motor control applications due to their
high power handling capabilities, fast switching speeds, and low power losses.

5. Motor Drive Circuits:
Semiconductor devices are employed in motor drive circuits to control the speed, torque,
and direction of electric motors. Integrated circuits (ICs) specifically designed for motor
control, such as motor driver ICs, incorporate power MOSFETs or IGBTs along with
control circuitry.
These ICs provide a convenient and compact solution for driving motors, offering
features like current sensing, protection mechanisms, and communication interfaces.

6. Pulse Width Modulation (PWM):
Pulse Width Modulation (PWM): Semiconductors enable the implementation of pulse
width modulation, a widely used technique in motor control.
 PWM involves rapidly switching the power semiconductor devices on and off to create
a variable-width pulse signal.
By adjusting the width of the pulses, the effective voltage and current supplied to the
motor can be controlled, allowing for precise speed and torque regulation.

7. Sensing and Feedback:
Sensing and Feedback: Semiconductors are also utilized in motor control systems for
sensing and feedback purposes.
For example, Hall effect sensors, which are semiconductor devices, can be integrated
into motors to detect the position and speed of the rotor. This information is then fed
back to the motor control system, enabling closed-loop control and improved accuracy
in maintaining desired motor parameters.

8. 3.2 Power Semiconductor device
The power semiconductor devices can be operated as switches by applying a control signals
to gate(a device to be controlled).

9. Classification
Power semiconductor switching devices can be classified on the basis of:
• Uncontrolled turn on and off (diodes)
• Controlled turn on and uncontrolled turn off (SCR)
• Controlled turn on and off (BJT, MOSFET, GTO, IGBT)
• Continuous gate signal requirement (BJT, MOSFET, IGBT)
• Pulse gate requirement (SCR, GTO)
• Bipolar voltage-withstanding capability (SCR, GTO)
• Unipolar voltage withstanding capability (BJT, MOSFET, GTO)
• Bidirectional current capability (TRIAC)
• Unidirectional current capability (SCR, GTO, BJT, MOSFET, DIODE)

10.  most commonly used power semiconductors in motor
control systems:
A. Semiconductor diodes
B. Silicon Controlled Rectifier (SCR)
C. Insulated Gate Bipolar Transistor (IGBT):
D. MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor):
E. Power Bipolar Junction Transistor (BJT):
F. Gate Turn-Off Thyristors (GTO):

11. A. Semiconductor diodes Motor Control
• A diode is an active electronic component that is made of semiconductor material. It
allows electric current to flow in one direction only. This means that when the current is
flowing in the desired direction, the diode will offer minimal resistance.
• However, it will have maximum resistance when the current is flowing in an undesired
direction. This is a key property that makes the diode applicable in various fields of
electrical and electronics engineering

12. What do diodes do in the motor control
circuits?
1. Current rectification: Rectification is the process of changing ac to
dc. Because diode allows current to flow in only one direction, they used
as rectifier. There are several ways of connecting diode to make rectifiers
to convert ac into dc.
The half wave rectifier makes use of only half of the ac input wave.
A less pulsating and greater average direct current can be produce by
rectifying both half cycle of the ac input wave, such a rectifier circuit
is known as a full wave rectifier

13. 2 Diodes as protectors in the motor control circuits
• Other than the motor itself, motor control circuits have other electronic components,
some of which are super sensitive to unregulated electric currents. This is where the
importance of diodes comes in. They are designed to provide protection against reverse
electric current.
• The normal operation of control motors leads to the generation of reverse currents. Even
after turning the main power off, there will be some electric current in the circuit. In
some cases, the current may flow back to the circuit and to other electronic components.

14. 3. Protect from the EMF interference
Fly back diodes are connected across inductors to provide protection against EMF
interference. They do this by providing an alternative path for this force to flow out of
the current.

15. B. SCRs and Motor Control
Silicon Controlled Rectifiers (SCRs), also known as thyristors, are
semiconductor devices that can control the flow of electric current in a
circuit.
how do SCR work in the motor control circuits?

16. Working Principle of SCR in Motor Control System
• By controlling the triggering signals and the commutation process, the SCR can
regulate the power supplied to the motor, enabling control over its speed, direction,
and other parameters.
• It's important to note that SCR-based motor control systems require additional
circuitry, such as gate trigger circuits, and protective measures, to ensure proper
operation, protect the device, and manage electrical noise.
Application of SCR in Motor control system
Motor Speed Control: SCRs can be used to control the speed of AC motors.
Motor Starting: SCRs can be employed in motor starting circuits
Motor Braking: SCRs used for dynamic braking or regenerative braking of motors
Motor Reversing: SCRs can reverse the direction of rotation of the motor.
AC Power Control: SCRs can be used for general AC power control applications.

17. C. BJT and Motor Control
• BJTs are commonly used in motor control systems that require high current handling
capabilities.
• They are known for their robustness and ability to handle high power levels.
• However, BJTs have higher on-state voltage drops compared to other power semiconductors,
resulting in higher power losses during operation.

18. A Bipolar Junction Transistor (BJT) can control a motor in a motor
control system by acting as a switch or an amplifier. Here's how it works
1.Switching Operation: In motor control systems, BJTs can be used as
switches to control the power supplied to the motor. A BJT operates in
either an "on" state or an "off" state.
• On State: When the BJT is in the on state, it acts as a closed switch,
allowing current to flow from the collector to the emitter. This
effectively powers the motor and allows it to operate.
• Off State: When the BJT is in the off state, it acts as an open switch,
blocking the current flow between the collector and the emitter. This
turns off the power supply to the motor, effectively stopping its
operation
2.Amplification: BJTs can also be used to amplify control signals that are
used to regulate the motor's operation. In this case, the BJT acts as an
amplifier to increase the strength of the control signals before they reach
the motor.

19. D.MOSFET and Motor Control
• MOSFETs are widely used in low to medium power motor control systems.
• MOSFEET can use both as amplifying and switching device.
• They offer fast switching speeds, low on-state resistance, and excellent efficiency.
MOSFETs are suitable for applications requiring high-frequency switching and where low
power losses are crucial.

20. The working principle of a MOSFET In motor control system:
• By controlling the gate voltage of the MOSFET, the motor control system can regulate the
power supplied to the motor, allowing for variable speed control, reversing the motor's
direction, and implementing other control strategies as required.
• It's important to note that the specific implementation and circuitry of MOSFET-based
motor control systems can vary depending on the application and requirements.
Application of MOSFEET in motor control system:
a) Switching Operation
b) PWM (Pulse Width Modulation) Control: in conjunction with PWM control techniques
to regulate the speed of the motor.
c) Motor Braking: MOSFETs can be used for dynamic braking or regenerative braking in
motor control systems.
d) Overcurrent Protection
e) Motor Reversing: MOSFETs can be used to control the direction of rotation of the
motor.
f) Motor Control Circuit: They can be employed in level shifting, gate driving, and other
control functions.

21. D. IGBT and Motor Control
• Insulated Gate Bipolar Transistor (IGBT): IGBTs are widely used in motor control
applications due to their high voltage and current handling capabilities.
• They combine the advantages of MOSFETs (Metal-Oxide-Semiconductor Field-
Effect Transistors) and bipolar junction transistors.
• IGBTs have fast switching speeds, low on-state voltage drop, and good thermal
performance, making them suitable for high-power motor control systems.

22. working principle of an IGBT in a motor control system
By controlling the gate voltage of the IGBT, the motor control system can
regulate the power supplied to the motor, allowing for variable speed control,
reversing the motor's direction, and implementing other control strategies as
required.
Application IGBT in a motor control system :
a) Soft Starting and Soft Stopping
b) Motor Protection
c) Energy Regeneration
d) Direction Control:
e) Variable Speed Control

23. E. GTO and Motor Control
• GTOs are specialized thyristors capable of being turned off by applying a negative
gate current. They are used in motor control systems that require bidirectional
power flow control, such as motor drives with regenerative braking capabilities.

24. How GTO works in motor control system
By precisely controlling the timing and duration of the gate signals, the GTO can be
switched on and off, enabling effective motor control in various applications.
• The Gate Turn-Off Thyristors (GTO) finds applications in motor control systems
where efficient and precise control of electrical power is required. Here are some
common applications of GTO in motor control:
a) Adjustable Speed Drives (ASDs):
b) Electric Traction Systems
c) Industrial Automation
d) Renewable Energy Systems
e) Process Control Systems
• These are just a few examples of the applications of GTO in motor control systems.
The versatility, reliability, and precise control capabilities of GTOs make them suitable
for a wide range of motor control applications across different industries.