Revision A
GE T2100 Treadmill
5-19
2021403-031
Theory of Operation: Drive Controller Theory
Drive Controller Theory
General Description
A brushless DC motor consists of permanent magnets that create a static
magnetic field and electromagnets that, when energized, provide motion.
The magnets attach to a shaft to form a rotor with an even number of
magnetic poles. One or more electromagnets are wound on a laminated
steel stator to form the motor phases. Typically, brushless DC motors
have four, six, or eight magnetic poles with three winding phases.
With multiple motor phases, there is always one of the phases that can
be energized to provide rotational torque-regardless of the rotor position
with respect to the stator. Energizing the phases in the proper sequence
and polarity provides constant unidirectional torque. Transistors have
replaced brushes to accomplish phase switching. Sensors determine the
rotor position and turn on the correct motor phase.
Phases and Power Switches
The most common arrangement of phases and power switches is the
three-phase, Y-connected windings with six power switches. Each phase
consists of two windings in series, spaced 120 electrical degrees apart.
Each phase can be energized in either direction by turning on two of the
six power devices. This arrangement of switches and motor windings is
identical to an AC motor drive. The number of electrical cycles per
mechanical revolution is equal to the number of rotor poles divided by
two.
Motor Torque
To control motor torque, it is necessary to control the current through the
motor windings since torque is directly proportional to motor current.
Rapidly switching the power devices on and off limits the effective
voltage applied to the motor winding. Using a feedback loop, a voltage
command controls the motor current. This is called the current loop or
inner loop of the drive.
Motor Speed
Control of motor torque is only half of the motor control process, since the
ultimate goal of a motor drive is to provide an adjustable motor speed.
The simplest speed control loop consist of a summing junction to
determine the difference between the desired motor speed and the actual
motor speed, along with a gain block that feeds into the current loop. The
current loop may be considered a single block with voltage as an input
and motor current as an output. The overall feedback loop is called the
velocity loop or outer loop of the drive. While this system controls motor
speed, it cannot control the exact motor speed since some error signal is
Summary of Contents for T2100
Page 1: ...GE T2100 Treadmill Service Manual 2021403 031 Revision A ...
Page 8: ...vi GE T2100 Treadmill Revision A 2021403 031 ...
Page 9: ...Revision A GE T2100 Treadmill 1 1 2021403 031 1 Introduction ...
Page 10: ...1 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 19: ...Revision A GE T2100 Treadmill 2 1 2021403 031 2 Equipment Overview ...
Page 20: ...2 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 27: ...Revision A GE T2100 Treadmill 3 1 2021403 031 3 Installation ...
Page 28: ...3 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 45: ...Revision A GE T2100 Treadmill 4 1 2021403 031 4 Maintenance ...
Page 46: ...4 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 51: ...Revision A GE T2100 Treadmill 5 1 2021403 031 5 Theory of Operation ...
Page 52: ...5 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 73: ...Revision A GE T2100 Treadmill 6 1 2021403 031 6 Troubleshooting ...
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Page 103: ...Revision A GE T2100 Treadmill 7 1 2021403 031 7 Assembly Disassembly ...
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Page 133: ...Revision A GE T2100 Treadmill 8 1 2021403 031 8 Ordering Parts ...
Page 134: ...8 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 137: ...Revision A GE T2100 Treadmill A 1 2021403 031 A Appendix A Technical Specifications ...
Page 138: ...A 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...
Page 143: ...Revision A GE T2100 Treadmill B 1 2021403 031 B Appendix B Electromagnetic Compatibility EMC ...
Page 144: ...B 2 GE T2100 Treadmill Revision A 2021403 031 For your notes ...