Function Of Main Parts; Optimal Voltage Control; Ipm; Afm (Active Filter Module) - Mitsubishi Electric MSC-A07WV Service Manual

5. IPM

Six power transistors that outputs the direct current waveform as three-phase alternating current waveform, the driving
circuit which operates the power transistors, and the overcurrent detecting circuit which protects the power transistors are
built into the IPM. It can simplify and miniaturize the control circuit.
6.AFM [Active Filter Module]
The circuit that detects power supply voltage waveform, the circuit that detects the current flowing in module, the switching
element that short-circuits between plus and minus pole of direct-current circuit, and the switching element driving current
are built into AFM.
The current waveform is automatically adjusted by controlling the interval of short-circuit between plus and minus pole of
direct-current circuit so that the waveform of actual current flowing to service power supply is synchronized with the phase
of power supply voltage waveform detected by AFM.

11-11-3. Function of main parts

SYMBOL
C61,C62, C63 SMOOTHING CAPACITOR
CT61, CT761 CURRENT TRANSFORMER
DS61, DS62 DIODE STACK
IPM INTELLIGENT POWER MODULE
L REACTOR
L61, L62 COMMON MODE CHOKE COIL
L63 NORMAL MODE CH6KE COIL
R
CURRENT-LIMITING RESISTOR
X64 RELAY

11-12. Optimal voltage control

The purpose of optimal voltage control is to operate the compressor at optimal
voltage that meets the load detected by the power factor of the compressor.
1. Optimal
As shown on the right the efficiency (ratio of output against input) of the
motor in the compressor becomes optimal when the sliding (ratio of differ-
ence between the actual number of rotation and the number of synchronous
rotation of motor) is one fixed value. The value of sliding can be calculated
from the power factor since the sliding and the power factor are mutually
related as shown in the table on the right. To make the value of sliding so
that the efficiency of motor is optimal, the power factor of the compressor is
detected. Then the detected power factor is controlled so that its efficiency
can be high. As a result, it is possible to operate the compressor at optimal
voltage.
2. How to determine the optimal voltage
Compare the detected power factor with the target power factor so that the efficiency of motor is optimal, the voltage
correction value is changed and the optimal output voltage is determined.
Optimal output voltage[V]= Standard voltage at certain frequency [V]x voltage correction value(%)
Target power factor minus detected power factor
(Calculated value is supposed to be "A".)
NAME
A[-2%
-2%<A<+2%
A]+2%
FUNCTION
It stabilizes the direct current voltage.
It measures the current of main power supply circuit.
It converts the alternating current voltage to direct current voltage.
It generates three-phase alternating current and operates compressor.
It is combined with DS62 to improve the power factor of power supply.
It eliminates and absorbs the electrical noise.
It absorbs the rush current not to run into the main power supply circuit
when the electricity is turned on.
It short-circuits the circuit to current-limiting resistor when the
compressor operates.
Calculation of voltage
correction value (%)
Previous voltage correction value minus 1
Same as previous voltage correction value
Previous voltage correction value plus 1
97
Power factor
1 slip
efficiency
0