This document provides an overview of electrical DC drives. It defines a DC drive as a speed control system for a DC electric motor that supplies voltage to operate the motor at a desired speed. There are two main types of DC drives - non-regenerative drives that only rotate in one direction and regenerative drives that can control speed, direction, and torque in four quadrants. Speed in DC drives can be controlled through either armature voltage control or field flux control methods. DC drives have applications in industries like steel mills, textiles, and machine tools due to their reliability, simple control, and cost effectiveness.

1. ELECTRICAL DC DRIVES

2. CONTENTS
 Introduction
 Defination
 Working principal
 Function
 Types of DC Drives
 Speed control method
 Application
 Advantages

3. INTRODUCTION
The d.c. drive remains an important speed-
controlled industrial drive, especially where the
higher maintenance cost associated with the d.c.
motor brushes (c.f. induction motor) is tolerable.
The controlled rectifer provides a low-impedance
adjustable ‘d.c.’ voltage for the motor armature,
thereby providing speed control.

5. WHAT IS DC DRIVES
• It is basically speed control system of a DC
electrical motor that supplies voltage to the
motor to operate at desired speed.

6. WORKING PRINCIPAL OF DC DRIVES
 In DC motors, the speed is proportional to the armature voltage
and inversely proportional to the field current.
 And also, the armature current is proportional to the motor
torque.
 Therefore, by increasing or reducing the applied voltage, the
speed of the motor is varied.

7. FUNCTIONS OF DC DRIVES
• A DC drive supplies voltage to the motor to operate at a desired speed.
• The motor draws current from this power source in proportion to the torque (load) applied to
the motor shaft.
• In this example an unloaded motor connected to a DC drive is being operated at 100% speed.

8. TYPES OF DC DRIVES
1.Non-regenerative DC Drive – This drive rotates only in one direction and hence also
called single quadrant drive.The non-regenerative DC motor drive does not have any
inherent braking capability. The motor is terminated only by removing the supply. Such
type of drive is used in a placed where high friction load or strong natural brake requires.
2.Regenerative DC Drive – It is a four quadrant drive, and it controls the speed, direction
and torque of a motor. Under the braking condition, this drive converts mechanical
energy and load into electrical energy which is returned to the power source.

9. SPEED CONTROL METHODS
OF DC DRIVES
Armature Voltage Control
Thismethod prefers becauseit has highefficiency, good transientresponse andgood speed regulation.Itprovides speed
control only below the ratedspeed because thearmaturevoltage cannotbe allowedto exceed theratedvalue.
Field Flux Control
Thismethod is usedfor controlling thespeed above theratedvalue.Normally, the maximum speed of themotor is twice
theratedspeed, andin thespecial motor, itis six times the ratedspeed.

10. ADVANTAGES OF DC DRIVES
 Lower cost
 Reliability
 Simple control
 It has high efficiency
 It is more economical

11. APPLICATIONS OF DC DRIVES
• Electric Traction
• Steel mills
• Printing mills
• Textile mills
• Paper mills
• Machine tools
• Cranes
• Hoists

12. THANK YOU