Common faults and maintenance countermeasures of frequency converters made in Taiwan

1 Introduction

The development of inverters should be said to have gone through a very long period of time. The Chinese inverter market has also experienced the dominance of Japanese inverters from the early 1980s to the mid-1990s, and now European and American inverters are gradually becoming dominant. In the middle of this we have to mention the inverter made in Taiwan. As a gathering place and processing center for semiconductor electronic products, the frequency converter, which is closely related to the semiconductor ic industry, has also made tremendous development in Taiwan. It also won a place for Taiwan inverter in the market. And because of its low price and good performance, it is favored by low-end users. The leading brands are mainly Delta, Tai'an, TECO, and other brands we can encounter are Edley, Lijia, Ningmao, Olin, Jiudong Songyi and so on.

2 Overview of inverters in Taiwan

Taiwan inverters are relatively simple in function, especially the early products. The main function of Tai'an Oulin is speed regulation, which is simple and practical. Such as Tai's early n1 series, and Olin's ol-2001 series, ol-4001 series. However, with the development of semiconductor technology and the increasing use requirements of users in objective use occasions, the functions of the inverter are becoming more and more abundant. The frequency converter in Taiwan has also made considerable progress. With the maturity of the control theory, the control method has been upgraded from the original v / f control to the voltage vector control. The main power device has also been improved from a high-power bipolar transistor gtr to an insulated gate Pole-type transistor igbt, the performance of the inverter is greatly improved.

In terms of function, although inverters made in Taiwan cannot be compared with those in Europe, America and Japan, the functions are becoming more and more perfect. Both Taian and Delta have rs-232 / 485 communication function, built-in pid function, Delta inverter also has pg card option, the parameters are also equipped with electronic gear settings, and the speed regulation is more accurate (vfd-v series) . Due to some peculiarities in the textile industry, Taian Inverter has launched the sv300 series inverter with built-in wobble frequency function. For Dongyuan Inverter, due to the adoption of Yaskawa's frequency conversion technology, Dongyuan Inverter is very close to Anchuan Inverter in terms of appearance and internal parameters, and its functions are also very similar. Due to the mature technology of Yaskawa frequency conversion, the quality is still quite reliable. The classification is also close to Yaskawa frequency conversion. The function is also very powerful, including the choice of multiple communication methods, built-in simple plc function and so on.

In terms of model classification, several major Taiwan brands are also more detailed. For example, Delta inverter includes general-purpose vfd-a series, fan-pump water pump-specific vfd-f series, simple vfd-s series, and vfd-v series that can be used for direct torque control. Taian inverters mainly include general-purpose n2 series, current vector control type v2 series, economical e2 series, and the most complete sv300 series. TECO inverter mainly includes high power 7200ga series, 7200pa series, medium and small power 7200ma, 7200cv series, and e2 and n2 series which are very similar to Taian inverter.

3 Common faults and maintenance

From the perspective of maintenance, we will make a discussion with the common faults of several common brand inverters.

For Taian inverters, the most frequently encountered faults are the n2 series. The common fault codes are overcurrent oc. There are many reasons: motor failure, acceleration time is too short, detection of ct damage, all may cause overcurrent faults. appear. In fact, it is the damage of the pim module that causes the most overcurrent alarm during maintenance. Sometimes it is often due to a short circuit on the drive circuit, which causes an overcurrent alarm when the power is turned on. It may also be caused by damage to the high-power transistor, resulting in three-phase output voltage If it is unbalanced, the inverter will display an overcurrent alarm during operation. Our common method to determine the source of the fault is to run the inverter without dragging the motor, and measure the output voltage to determine whether the motor has a problem or the inverter is faulty. If the inverter is faulty, we have to judge whether it is the fault caused by the damage of the pim module or the fault caused by the misdetection of the detection circuit. We can judge the quality of the pim module through measurement, but it is worth noting that we cannot ignore the measurement of the drive circuit waveform. The lower bridge drive of the Taian n2 series inverter adopts the pc929 drive optocoupler with short circuit protection. The damage of the pim module is also easy to cause damage to the drive optocoupler. The damage of the detection circuit is mainly that the damage of the Hall sensor will also cause an overcurrent alarm.

The design of the switching power supply of the n2 series inverter is the current popular practice of the switching power supply. A μc3842 is used as a waveform generator to adjust the duty ratio of the switch tube k1317 to achieve the purpose of adjusting the output. The design of the whole circuit is simple and reliable, and it is widely used. However, due to the short circuit of the load carried by the switching power supply, or the sudden change of the operating voltage of the switching power supply, the switching power supply may be damaged. The problem is generally on the μc3842 chip, but if the external power supply changes suddenly, it may also cause damage to the pulse transformer. In Tai'an n1 series inverters, the damage of pulse transformers is still relatively large, but the reason is different from the damage of n2 series inverters. Mostly related to the process when the pulse transformer is wound.

   The most frequently encountered Delta inverter is the damage to the switching power supply. Such as Delta's vfd-a series inverter. Its switching power supply adopts a symmetrical design structure. There are two switching tubes to adjust the output voltage together. The problem is often in the driving circuit of the switching tube. In addition, the pulse transformer of the switching power supply is also a vulnerable part.

The 7200ga of TECO adopts the technology of Yaskawa 616g3 series inverter. What we encounter more is sc failure and cpf00-cpf04 failure. Of course, the damage of the switching power supply is also one of the common faults. Most of the SC short-circuit faults are caused by the damage of the power module, and the short-circuit of the triggering pole of the power module often results in a short-circuit fault upon power-on. Damage to the drive circuit can also cause sc failure. Often, the SC failure occurs as soon as it is running. Then we can only eliminate the fault by measuring the power module and detecting the driving waveform. For cpf00-cpf04 failure, the problem is basically on the cpu board, which is relatively difficult to detect. The general fault point is on the eeprom that can be erased online. In addition, the chip with integrated CPU processor and program is also more prone to problems. However, when we replace the chip for maintenance, we should pay attention to the control of the temperature of the hot air fan. Don't burn the chip.

4 Conclusion

It should be said that the failures of several major brand inverters produced in Taiwan are still diverse. The above list is only a small part of common failures. I hope that more people who are engaged in the frequency conversion speed regulation industry will join this rank in the future. , To better solve some problems for the majority of users.