Servo Motors
BALDOR ELECTRIC COMPANY
SERVO CONTROL FACTS
A HANDBOOK EXPLAINING THE BASICS OF MOTION
MN1205
TABLE OF CONTENTS
TYPES OF MOTORS . . . . . . . . . . . . . . 3 OPEN LOOP/CLOSED LOOP . . . . . 9 WHAT IS A SERVO . . . . . . . . . . . . . . 11 COMPENSATION . . . . . . . . . . . . . . . 13 TYPES OF CONTROLS . . . . . . . . . . . 15 TYPES OF FEEDBACK DEVICES . 17 TYPES OF ACTUATORS . . . . . . . . . . 22
Page 2
Servo Control Facts
TYPES OF MOTORS
The direct current (DC) motor is one of the first machines devised to convert electrical energy to mechanical power. Its origin can be traced to machines conceived and tested by Michael Faraday, the experimenter who formulated the fundamental concepts of electromagnetism. These concepts basically state that if a conductor, or wire, carrying current is placed in a magnetic field, a force will act upon it. The magnitude of this force is a function of strength of the magnetic field, the amount of current passing through the conductor and the orientation of the magnet and LD FIE conductor. The direction in which C ETI this force will act is dependent on the GN MA direction of current and direction of the magnetic field. Electric motor design is based on the placement of conductors (wires) in a FORCE magnetic field. A winding has many conductors, or turns of wire, and the CURRENT contribution of each individual turn adds to the intensity of the interaction. The force developed from a Fig. 1 - CONCEPT OF ELECTROMAGNETISM winding is dependent on the current passing through the winding and the magnetic field strength. If more current is passed through the winding, then more force (torque) is obtained. In effect, two magnetic fields interacting cause movement: the magnetic field from the rotor and the magnetic field from the stators attract each other. This becomes the basis of both AC and DC motor design.
AC MOTORS
Most of the world's motor business is addressed by AC motors. AC motors are relatively constant
SERVO CONTROL FACTS
A HANDBOOK EXPLAINING THE BASICS OF MOTION
MN1205
TABLE OF CONTENTS
TYPES OF MOTORS . . . . . . . . . . . . . . 3 OPEN LOOP/CLOSED LOOP . . . . . 9 WHAT IS A SERVO . . . . . . . . . . . . . . 11 COMPENSATION . . . . . . . . . . . . . . . 13 TYPES OF CONTROLS . . . . . . . . . . . 15 TYPES OF FEEDBACK DEVICES . 17 TYPES OF ACTUATORS . . . . . . . . . . 22
Page 2
Servo Control Facts
TYPES OF MOTORS
The direct current (DC) motor is one of the first machines devised to convert electrical energy to mechanical power. Its origin can be traced to machines conceived and tested by Michael Faraday, the experimenter who formulated the fundamental concepts of electromagnetism. These concepts basically state that if a conductor, or wire, carrying current is placed in a magnetic field, a force will act upon it. The magnitude of this force is a function of strength of the magnetic field, the amount of current passing through the conductor and the orientation of the magnet and LD FIE conductor. The direction in which C ETI this force will act is dependent on the GN MA direction of current and direction of the magnetic field. Electric motor design is based on the placement of conductors (wires) in a FORCE magnetic field. A winding has many conductors, or turns of wire, and the CURRENT contribution of each individual turn adds to the intensity of the interaction. The force developed from a Fig. 1 - CONCEPT OF ELECTROMAGNETISM winding is dependent on the current passing through the winding and the magnetic field strength. If more current is passed through the winding, then more force (torque) is obtained. In effect, two magnetic fields interacting cause movement: the magnetic field from the rotor and the magnetic field from the stators attract each other. This becomes the basis of both AC and DC motor design.
AC MOTORS
Most of the world's motor business is addressed by AC motors. AC motors are relatively constant