MTE1122T-I/SO Microchip Technology, MTE1122T-I/SO Datasheet - Page 3

• Manufacturer Part Number: MTE1122T-I/SO
• Description: IC ENERGY CONTROLLER 18-SOIC
• Manufacturer: Microchip Technology

Specifications of MTE1122T-I/SO

• Voltage - I/o High: 0.7V
• Voltage - I/o Low: 0.6V
• Current - Supply: 1.8mA
• Voltage - Supply: 4 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 18-SOIC (0.300", 7.50mm Width)
• Meter Type: Single Phase
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification

CIRCUIT DETAILS
The MTE1122 consists of a high-performance 8-bit
microcontroller (U3) with embedded proprietary algo-
rithms, which monitors the voltage across the motor
(U1), the voltage zero-crossing (Q2) and the current
zero-crossing (by monitoring the signal on Q3). By mea-
suring the time between voltage and current zero-cross-
ings, it calculates the amount of load on the motor.
U1 and R10-R13 form a differential amplifier with a gain
of 1/48. C4 limits noise sensitivity.
C2 through C6 and components in between rectify and
filter line voltage to provide V
Q1 and associated components provide power-up
reset for the MTE1122.
L1 and C8 form an LC filter for the 5V power supply.
U2 is an opto-triac to trigger the power triac. Q3 is the
triac, which in this circuit is rated at 15A.
D3 and R7 are used to indicate “normal operation” of
the circuit, and may be left out if desired.
As stated above, it turns out that the energy
consumption of a motor running only partly loaded can
be lowered by decreasing the current flowing into the
motor windings. This can be accomplished by lowering
the voltage across the motor windings. If the voltage is
not increased when the motor load increases, the
internal reactance of the motor decreases, and the wind-
ings will draw too much current, and could overheat and
be damaged. Because the MTE1122 is an intelligent
controller, it is able to monitor motor voltage and motor
load, and make corrections within 8 ms, well before
there is any potential for motor damage.
See Figure 10 for circuit waveforms.
FIGURE 2:
1995 Microchip Technology Inc.
ENERGY SAVINGS
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0
CC
1 0
.
2 0
3 0
4 0
Percent Load
5 0
ENERGY SAVINGS
Reducing the voltage to the motor cuts its power draw.
By reviewing Table 1, it can be seen that at no load, the
1/3 HP test motor is dissipating 120W, much of it as
heat. With the MTE1122 managing the power load, this
drops to 50W, a savings of 58%. At full load, the figures
are, respectively, 428W and 406W, for a savings of 5%.
The degree of savings are presented in Table 2.
This data is presented graphically in the following
figures.
Actual performance figures may vary based on motor
size, motor load and motor construction.
ALTERNATIVE APPROACH
There is another way to increase motor efficiency. This
approach is to add another winding to the motor, and
phase-shift it with capacitance. This produces what is
known as a capacitor-run motor, and results in a motor
with a power factor close to 1.0 regardless of its load,
and considerably lowered idle power consumption. It is
a more efficient motor, and produces less vibration.
This approach, however, is neither cost-effective in
motors less than 1 hp, nor in motors for residential use.
Thus, for lowest-cost approaches, use of the MTE1122
and associated circuitry is probably the best method of
improving motor efficiency.
6 0
7 0
8 0
9 0
AN599
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1 0 0