Ig module is damaged due to poor heat dissipation


The frequency converter makes a sudden sound during operation, and the external
connection is burned. It is found that the IGBT module of the frequency
converter is damaged after disassembly. Through the test of relevant boards, it
is found that the IGBT trigger circuit is damaged, and other plates are normal.
When removing the frequency converter board, it was found that there were a lot
of oil and dust on the power board and current detection board. Turn on the fan
of the heat sink of the frequency converter and see that the heat sink is also
covered with oil and sundries, which completely blocks the heat dissipation
channel of the frequency converter. It is inferred that the Ig module of the
frequency converter is damaged due to poor heat dissipation.


Maintenance process: first, completely disassemble the frequency converter,
remove the heat sink of the heat dissipation channel, clean the heat sink with
air pressure gas, and clean all the internal structural parts and boards of the
frequency converter. Install the IGBT module. When installing the IGBT module,
install it in sequence according to the requirements of the module, with
appropriate torque. Repair the trigger circuit, and then install other devices
in turn. After installation, conduct static test. After the static test results
are good, conduct power on test and load test. The on load test is qualified
and the maintenance is completed successfully.


Experience summary: Based on the maintenance of several frequency converters in
different models and different use environments, it is concluded that the main
reason for the damage of frequency converter IGBT module is the poor use
environment, which leads to the damage of electronic components on gate drive
card and the blockage of heat dissipation channel of frequency converter* The
easily damaged devices are voltage stabilizing tube and optocoupler. Check
whether there is a problem in the driving circuit. Compare whether the
resistance of each trigger terminal is consistent when power is off. The
voltage waveform at the trigger end can be measured after power on. However,
some frequency converters cannot be started without being installed into the
module. At this time, a false load is connected in series at the p-end of the
module to prevent the module from being burnt out due to touching the
originator or other lines by mistake during inspection.


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Knud Jansen, manager of mechanical control and automation products in ABB's
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to software developers when developing and testing PLC code modules."
The PLC crane control system of NTK is installed in the protected cabinet in
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Working principle of AC servo motor
The rotor inside the servo motor is a permanent magnet. The U / V / W three-
phase electricity controlled by the driver forms an electromagnetic field. The
rotor rotates under the action of this magnetic field. At the same time, the
encoder feedback signal of the motor is sent to the driver. The driver compares
the feedback value with the target value to adjust the rotation angle of the
rotor. The accuracy of the servo motor depends on the accuracy of the encoder
(number of lines).
4. Servo motor? How many types? What are the characteristics of the work?
A: servo motor, also known as executive motor, is used as an executive element
in the automatic control system to convert the received electrical signal into
angular displacement or angular speed output on the motor shaft. It is divided
into DC and AC servo motors. Its main feature is that when the signal voltage
is zero, there is no rotation, and the speed decreases at a uniform speed with
the increase of torque,
What are the functional differences between AC servo motor and brushless DC
servo motor?
AC servo is better because it is controlled by sine wave and the torque ripple
is small. DC servo is trapezoidal wave. But DC servo is relatively simple and
cheap.
Since the 1980s, with the development of integrated circuit, power electronics
technology and AC variable speed drive technology, permanent magnet AC servo
drive technology has made outstanding development. Electrical manufacturers in
various countries have launched their own AC servo motor and servo driver
series products, which have been continuously improved and updated. AC servo
system has become the main development direction of contemporary high-
performance servo system, which makes the original DC servo face the crisis of
being eliminated. Since the 1990s, the digital servo motor drive system has
been used all over the world. The development of AC servo drive in the field of
transmission is changing with each passing day. Compared with DC servo motor,
permanent magnet AC servo motor has the following main advantages:
(1) there is no brush and commutator, so it works reliably and has low
requirements for maintenance.
⑵ the heat dissipation of stator winding is convenient.
⑶ small inertia, easy to improve the rapidity of the system.
(4) it is suitable for high-speed and large torque working state.
(5) smaller volume and weight under the same power.