Drive Controller Theory; General Description; Phases And Power Switches - GE T2100 Service Manual

Theory of Operation
J8 BDM Connector (cont'd.)
PIN #
J8–4
J8–5
J8–6
J9 Power Board to Processor Board Connector
PIN #
J9–1
J9–2
J9–3
J9–4
J9–5
J9–6
J9–7
J9–8
J9–9
J9–10

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
70
NAME
+5V ISO
RST*
ISOGND
NAME
+5.1V
DGND
EN_ELEV
DGND
LIMIT*
DGND
ELEV_FB
DGND
UP/DOWN*
+24V
T2100 Treadmill
TYPE FREQ
IN/
OUT
PWR OUT DC
IN
LOGIC PULSE
COM OUT DC
TYPE FREQ
IN/
OUT
PWR IN DC
COM IN DC
LOGIC OUT PULSE
COM IN DC
LOGIC IN PULSE
IN
COM DC
ANA IN
DC
COM IN DC
LOGIC OUT PULSE
PWR
OUT DC
COMMENT
ISO Power Supply
uC Reset Signal
ISO GND Supply
COMMENT
Digital Power Supply
Digital Gnd Supply
Elevation Enable Control
Digital Gnd Supply
Limit Switch Feedback
Digital Gnd Supply
Pot Elevation Feedback
Digital Gnd Supply
Elevation Direction Ctrl
Digital Power Supply
2021403-120F