MTE1122 MICROCHIP [Microchip Technology], MTE1122 Datasheet - Page 2

• Manufacturer Part Number: MTE1122
• Description: Energy Management Controller IC
• Manufacturer: MICROCHIP [Microchip Technology]

MTE1122
FUNCTIONAL DESCRIPTION
Single-phase induction motors run most efficiently at
full load. As the applied load lessens, a greater portion
of the energy consumed by the motor is wasted, mostly
as heat.
It is estimated by the EPA that 50% of the energy pro-
duced in the US is consumed by small electric motors,
and that 20% of this energy does no useful work. There
are perhaps three major reasons for this:
1.
2.
3.
Number 1 above can be corrected by proper design.
For example, in modern refrigerators, the compressor
systems have been optimized quite effectively. Num-
bers 2 and 3 can not be improved using traditional
approaches. This is where the MTE1122 provides a
new, cost-effective solution.
The MTE1122 calculates the amount of load on a motor
connected to it, and adjusts the motor’s supply voltage
to match that load. For example, if the load is lower
than the motor’s rated load, the voltage to the motor
can be reduced, thus decreasing the energy used by
the motor.
FIGURE 3: MOTOR EFFICIENCY
DS21112B-page 2
Over-specification -- sometimes its easier or
costs no more to specify a larger motor than
determine actual loads.
Worst case design -- pumps, conveyers, fans,
and the like must be able to operate properly
with clogged filters, maximum heads, or speci-
fied loads. If filters are clean, or loads are lower,
the motor will be running only partly loaded.
Idle time -- many times, systems can’t be shut
down conveniently when not in use.
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0
With E.M.C.
1 0
2 0
Without E.M.C.
3 0
Percent Load
4 0
Preliminary
5 0
6 0
A 1/3 HP motor will typically see 85 VAC at no load
when powered through the MTE1122, for an energy
savings of as much as 58%.
A system block diagram is shown in Figure 1. A graph
of energy savings vs. motor load is shown in Figure 2.
A graph of motor efficiency with and without an
MTE1122-based energy management controller (EMC)
is shown in Figure 3. The data for the graphs are
shown in Table 1. These figures are based on a 1/3 HP
induction motor coupled to a dynamometer. Actual
savings may vary based on motor size, motor load and
motor construction.
PINOUT DESCRIPTIONS
P-Sense - analog input that is used by the device to
measure the load voltage.
Gate Enable - analog input that monitors the voltage
across the triac. It is used as a current feedback mech-
anism.
IND - TTL-compatible output that indicates that the sys-
tem is operating normally. It is intended to control an
LED or another indicator device.
ZC-Sense - TTL-compatible input that is used to deter-
mine the zero crossing point of the AC voltage wave-
form.
TTRIG - TTL-compatible output that is used to drive the
triac.
RESET - TTL-compatible input used to reset the device
by holding this pin low.
OSC1, OSC2 - Oscillator crystal or resonator connec-
tions.
7 0
8 0
9 0
1995 Microchip Technology Inc.
1 0 0