96
11-11-2. Outline of main power supply circuit
1. At the start of operation
Rush current is generated the instant the electricity is turned on to the main power
supply circuit to operate the compressor.
To prevent the rush current from running into the main power supply circuit, R64A, R64B (Current-limiting resistor) absorbs
the rush current.
After the rush current is absorbed, X64 (Relay) is ON and the circuit to R is
short-circuited, then the electricity to R is bypassed.
When X64 is ON, the system starts the operation of compressor.
2. At normal operation
The noise of alternating current of power supply is eliminated by L61, L62 (Common mode choke coil).
Then DS61, DS62 (Diode stack) performs full-wave rectification of alternating current and the
alternating current is converted to direct current.
C61, C62 and C63 (Smoothing capacitor) stabilizes the power supply converted to direct current from alternating current
and supplies it to IPM (Intelligent power module).
Direct current rectified by DS61, DS62 is converted to three-phase alternating current by IPM.
Microcomputer installed in the electronic control P.C. board controls frequency and voltage of three-phase alternating
current converted by IPM.
Three-phase alternating current is supplied from IPM to the compressor with frequency and voltage decided by
microcomputer based on various kinds of information.
CT61, CT761 (Current transformer) measures the current of main power supply circuit.
3. Power-factor improvement of power supply and harmonics control
Although C61, C62, and C63 [smoothing capacitor] are used in this inverter circuit in order to supply direct-current stably,
since the charge current to a capacitor turns into intermittent current in the stable circuit with only a capacitor, power factor
of power supply gets worse and harmonics ingredient also becomes large.
Then, AFM [active filter module] and L [reactor] have been arranged on direct-current circuit, and the improvement of
power factor and generating of harmonics are controlled by bringing the intermittent current waveform of alternating
power supply close to sine wave synchronized with the power supply voltage waveform. (Note 1)
Note 1: When short-circuited between plus and minus pole of direct-current circuit,
alternating power supply current flows. By controlling time of short-circuiting to flow proper amount of current in the
intermittent portion of alternating power supply current constantly, the current waveform of alternating power supply is
brought close to sine wave.
4. Removal of electric noise
Because of the noise filter circuit formed by L61 and L62 [CMC coil] and the capacitor on the noise filter board, the electric
noise of the alternating power supply supplied to the main power supply circuit is removed.
Moreover, common mode noise is absorbed with the above-mentioned noise filter, and the normal mode noise is
absorbed in the noise filter circuit formed by L63 [NMC coil] and the capacitors [C650A, C650B, and C650C] on the
control board so that the electric noise generated in the inverter circuit may not leak out.
POWER
SUPPLY
X64
R64A/R64B
DS61/DS62
AFM
L
L61/L62
L
N
U
U
V
V
W
W
P
N
NOISE FILTER
P.C.BOARD
ELECTRONIC CONTROL P.C. BOARD
CT61
L63
CT761
+
+
-
MC
IPM
11-11-1. INVERTER MAIN POWER SUPPLY CIRCUIT
OB307A4.qxp 03.2.19 4:10 PM Page 96
