Motor Torque; Motor Speed; Electrical Requirements - GE T2100 Service Manual

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 required to drive the
current loop. The actual motor speed is dependent on the speed command, the load,
the error gain, and the characteristics of the motor itself.
Adding an integrator to the error amplifier allows exact speed control. Any speed error
results in an output from the integrator that builds with time and causes an output
to the current loop. This loop, therefore, will seek zero speed error. This is the type of
velocity loop used in the T2100 Treadmill drive.

Electrical Requirements

The two black wires that exit the side of the enclosure supply power to the drive. The
power source should be single phase, 200–240VAC, 50–60Hz, 16A.
Maximum input current is 16A.
Fuses should be FLM 20A SLO only. Substituting a different fuse type may cause
a fire or safety hazard.
The orange wire from the side of the enclosure is connected to the sheetmetal
enclosure and should be connected to the designated terminal on the power terminal
block. Do not connect this wire to the T2100 Treadmill frame which would cause a
safety hazard.
The motor wires exit through the flexible conduit on the left side of the enclosure.
These wires carry the pulsed 320V to the motor. Be sure to observe proper phasing
when connecting these wires. The drive will not operate with incorrect phasing.
NOTE:
If the motor is disconnected, do not let the motor wires short to each other or any
other point. If it rotates, the motor will function as a generator, and it may be
damaged or cause a shock hazard. The drain wire should be connected to the
motor frame. Make sure this connection is secure.
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T2100 Treadmill
Theory of Operation
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