Mitsubishi Electric MSC-GE-VB Service Manual page 26

Input current waveform without PAM
Due to the time of no electricity;
• Power factor gets worse.
• Harmonic gets increased.
Input current
Input voltage
No electricity runs into
diode module because the
voltage at both sides of smoothing
capacitor is higher than input voltage.
4. Intelligent power module
INTELLIGENT POWER MODULE consists of the following components
• IGBT (x6): Converts DC waveform to 3-phase AC waveform and outputs it.
• Drive Circuit: Drives transistors.
• Protection circuit: Protects transistors from overcurrent.
Since the above components are all integrated in INTELLIGENT POWER MODULE, INTELLIGENT POWER MODULE
has a merit to make the control circuit simplify and miniaturize.
5. Elimination of electrical noise
NOISE FILTER CIRCUIT, which is formed by *CMC COILS capacitors placed on P.C. board, eliminates electrical noise of AC power that
is supplied to main power supply circuit. And this circuit prevents the electrical noise generated in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
MXZ-3B54VA MXZ-3B68VA MXZ-4B71VA MXZ-4B80VA MXZ-5B100VA
MXZ-3C54VA MXZ-3C68VA MXZ-4C71VA MXZ-4C80VA MXZ-5C100VA
1. At the start of operation
Main power supply circuit is formed when RELAY is turned ON at COMPRESSOR startup.
To prevent rush current from running into the circuit when power supply is turned ON, RESISTOR is placed in sub circuit.
2. At normal operation
When AC runs into noise fi lter P.C. board, its external noise is eliminated in NOISE FILTER CIRCUIT.
After noise is eliminated from AC, it is rectifi ed to DC by REACTOR and POWER FACTOR CORRECTION MODULE. If the
operating frequency becomes 25 Hz or more, DC voltage rises to 370 V.
DC voltage, to which AC has been rectifi ed by process
TELLIGENT POWER MODULE.
The DC (Bus voltage), which has been stabilized in process
MODULE and supplied to COMPRESSOR.
CURRENT TRANSFORMER which is placed in the power supply circuit to COMPRESSOR, is used to measure the value
of phase current and locates the polar direction of rotor with algorithm. PWM (Pulse width modulation) controls impressed
voltage and frequency with those pieces of information.
3. Power factor improvement
Booster coil reactor and POWER FACTOR CORRECTION MODULE rectify AC to DC and control its voltage.
In the motor drive system of sine wave control, power factor can be improved by reducing harmonics. POWER FACTOR
CORRECTION MODULE and reactor stabilize the voltage of DC supplied to inverter circuit and make its waveform smooth.
4. Intelligent power module
INTELLIGENT POWER MODULE consists of the following components.
• IGBT (x6): Converts DC waveform to 3-phase AC waveform and outputs it.
• Drive Circuit: Drives transistors.
• Protection circuit: Protects transistors from over current.
Since the above components are all integrated in INTELLIGENT POWER MODULE, INTELLIGENT POWER MODULE has a
merit to make the control circuit simplifi ed and miniaturized.
5. Elimination of electrical noise
NOISE FILTER CIRCUIT, which is formed by *CMC COILS, *NMC COILS and capacitors placed on P.C. board, eliminates
electrical noise of AC power that is supplied to main power supply circuit. This circuit also prevents electrical noise generated
in the inverter circuit from leaking out.
*CMC COILS; Common mode choke coils
*NMC COILS; Normal mode choke coils
Energized time is short in
case L inductance is small.
Input current waveform with PAM
Owing to the increase of energized time;
• Power factor gets better.
• Harmonic gets suppressed.
Release of energy stored in L.
Compulsory energizing
by switching.
, is stabilized by SMOOTHING CAPACITOR and supplied to IN-
, is converted to 3-phase AC by INTELLIGENT POWER
26
Peak gets down.
Energized time is
extended by
optimization
of L inductance.