Inverter System Control - Mitsubishi Electric MS-A•WA Service Technical Manual

2-7. INVERTER SYSTEM CONTROL

2-7-1. MUZ-A09/12/15/17
MUY-A15/A17
2-7-1-1. Inverter main power supply circuit
POWER P.C. BOARD
Power
supply
Function of main parts
SYMBOL
IPM INTELLIGENT POWER MODULE
C63A/C63B/C63C
SMOOTHING CAPACITOR
CT761/CT781
CURRENT TRANSFORMER
CT CURRENT TRANSFORMER
DB61
DIODE MODULE
R64A, R64B CURRENT-LIMITING RESISTOR
X64 RELAY
DIODE MODULE
DB65
TR821
SWITCHING POWER TRANSISTOR
L61 REACTOR
2-7-1-2. Outline of main power supply circuit
1. At the start of operation
Main power supply circuit is formed when X64 (Relay) is turned ON at compressor startup.
To prevent rush current from running into the circuit when power supply is turned ON,
R64A and R64B (Current-limitting resistor) are placed in sub circuit.
2. At normal operation
1 When AC runs into POWER P.C. board, its external noise is eliminated in the noise filter circuit.
2 After noise is eliminated from AC, it is rectified to DC by DB61 (Diode module).
3 DC voltage, to which AC has been rectified by process 2, is stabilized by C63A, C63B and C63C (Smoothing capacitor)
and supplied to IPM (Intelligent power module).
4 DC voltage, which has been stabilized in process 3, is converted to three-phase AC by IPM and supplied to
compressor.
5 CT761 and CT781 (Current Transformer), which are placed in the power supply circuit to compressor, are used to
measure the value of phase current and locate the polar direction of rotor with algorithm. PWM (Pulse width modulation)
controls impressed voltage and frequency with those information.
L62 L63
R64A R64B
X64
CT
NAME
INVERTER P.C. BOARD
L61
DB61
TR821
DB65
Booster chopper circucuit
It supplies three-phase AC power to compressor.
It stabilizes the DC voltage.
It measures the current of the compressor motor.
It measures the value of current which is supplied to the main power
supply circuit.
It converts the AC voltage to DC voltage.
It absorbs the rush current not to run into the main power supply circuit
when the electricity turns ON.
It short-circuits the resistance which restricts rush current during the
normal operation after the compressor startup.
Booster
It improves power factor.
chopper
It rectifies AC and controls its voltage.
circuit
12
U
C63A
P
W
+
CT761
C63B
V
C63C
N
W
CT781
IPM
FUNCTION
U
MC
V