Fuji inverter drive plate test
The Fuji inverter drive board is mainly integrated with the signal amplifier that drives the IGBT circuit. The role of the drive circuit is to control the IGBT module to complete the inverter function after the six PWM signals on the CPU motherboard are separated by optical coupling and amplified. It contains the isolation circuit, the amplifier circuit and the drive power circuit. Moreover, the driver of the upper three bridges is an independent power supply, and the driver of the lower three bridges is a public power supply. The drive circuit has problems. Generally, the performance of a certain road is worse, or devices such as optical coupling and resistance are burned., Or if the drive power supply voltage is not normal, this will cause problems with the IGBT transmission, which will cause the three-phase voltage output to be unbalanced, as long as the IGBT module is fried, or the three-phase imbalance, or the problem of Overflow, etc.. Check and repair the drive plates.
The most common characterization of the drive circuit is the three-phase voltage current imbalance and the output phase deficit. If a converter is quickly melted or the IGBT is broken, do not directly go to the new accessories. At this time, the drive circuit needs to be checked. See if there's a fire or a discoloration. As long as the WVW three-phase output is unbalanced, or there is a wobble at low frequencies, starting and overcurrent overload alarms, etc., you must carefully check the drive plate. When determining that the drive plate is normal and the IGBT module is required, the P foot needs to be disconnected from the bus, and several large bulbs are connected in series to be powered by a current limiting Resistor.
If there is a problem with the drive circuit, it will generally see obvious traces of damage. For example, a capacitor capacitor transistor or even a circuit board will have anomalies such as bursts, breakwires, and discoloration. In the absence of a complete circuit diagram, simple measurement comparisons are generally used. Check, If there is a normal board to compare is the most ideal, if not, in different circuits to do a separate comparison. You can simply clean up dirty dust and stains. If you find obvious burning components, change them directly, and break the wire, you can directly repair and weld them back. The optical coupling can be removed and measured offline to determine whether it is good or bad. Conditionally, an oscilloscope can be used to measure the output waveform of various driving signals without the IGBT installed, and the amplitude and phase of the pulses can be compared. And the market is not good at buying good quality, many times need to change multiple times to screen judgment.
Suspected that the drive circuit is not normal, you can first disconnect the IGBT and the drive circuit, and use the multimeter resistance meter to simply measure whether the resistance of the 8-way drive circuit is the same. The resistance value of some inverter may not be the same, like the Japanese Fuji Mitsubishi. There is a difference, So it's for reference only. Then the voltage is measured by electricity. The normal DC voltage is about 15 volts. After driving, it is about 4-6 volts. If all are relatively balanced, the IGBT module can be reinstalled. -Yeah.
This is the driving circuit of the U-phase bridge arm of the Fuji inverter. The GU and EU are pulse signal outputs. They are connected to the GE ends of the IGBT module respectively. When the repair is done, the drive board and the main power supply have been disconnected. It comes out by adding a measurement circuit to the dotted wire frame. After electricity, by starting and stopping, a 250-mA current file is connected to the MN two points, and then a 3W15 Ohm circuit is used to form a loop. Each driving current that drives back is measured separately. It is normally about 150 mA. If there is only 50 mA on a certain road, the installed machine will have an alarm OC overcurrent, which is caused by insufficient driving capacity. Later inspections found that it was caused by the decrease in the capacity of the electrolytic capacitor DC41, and the problem was solved after replacement. *
The Siemens 6SE 70 inverter burned an IGBT, so it is necessary to simply check whether the drive circuit board is normal. After simply measuring the voltage and resistance, it does not dare to directly transmit the test machine, and it is not convenient to connect the light bulbs on the DC bus to limit the flow. Finally, a 24-volt voltage is added to the X9 end, and then the DC bus also supplies a 24-volt DC voltage, sets P372 = 1, and then measures the output voltage, which is basically balanced, followed by a three-phase 380 Volt small motor with a low power of 80 watts., working in 1.5hezi, It is also normal to restore normal power supply at the end, idling normal, and then the load is also balanced.