Abstract : This paper introduces the implementation technology of an inverter fault diagnosis system based on Agent technology. It solves the problems of software design complexity caused by the uncertainty of the fault diagnosis process and software maintenance issues when the system undergoes dynamic changes (personnel changes, product improvements, new product development, and hardware changes in virtual instruments). The effectiveness and superiority of Agent technology are demonstrated, and a new approach is provided for similar complex software designs. Keywords : Agent; Fault diagnosis; Inverter fault detection and diagnosis technology is an applied interdisciplinary field. Its theoretical foundation lies in modern control theory, computer engineering, mathematical statistics, signal processing, pattern recognition, artificial intelligence, and related applied disciplines. Fault diagnosis (FD) originated from (mechanical) equipment fault diagnosis, and its full name is Condition Monitoring and Fault Diagnosis (CMFD). It includes two aspects: first, monitoring the operating status of equipment; second, analyzing and diagnosing equipment faults after abnormalities are detected. Equipment fault diagnosis has developed along with equipment management and equipment maintenance. European countries, under the impetus of the Federation of European Maintenance Societies (FENMS), primarily followed the UK's Terotechnology approach; the US adopted Logistics; and Japan absorbed the characteristics of both, proposing the concept of Total Productive Maintenance (TPM). Since the Apollo program began in 1961, the US experienced a series of accidents caused by equipment failures, leading to the establishment of the Machinery Failure Prevention Group (MFPG) in 1967, spearheaded by NASA and led by the Office of Naval Research (ONR), which actively engaged in technical diagnostic research. The US remains a world leader in diagnostic technology in cutting-edge sectors such as aviation, aerospace, military, and nuclear energy. In the 1960s and 70s, the UK's Machine Health and Condition Monitoring Association (MHMG & CMA), led by Colacott, pioneered research into fault diagnosis technology. The UK holds a leading position in friction and wear monitoring and diagnosis of automotive and aircraft generators. Nippon Steel in Japan developed diagnostic technology in 1971 and achieved practical application in 1976. Japanese diagnostic technology is a leader in sectors such as steel, chemicals, and railways. China's fault diagnosis technology started relatively late, only beginning to explore equipment diagnostics in 1979. Currently, China's diagnostic technology is well-appointed in industries such as chemical engineering, metallurgy, and power. After more than 30 years of research and development, fault diagnosis technology has been applied to fields such as aircraft autopilot, artificial satellites, space shuttles, nuclear reactors, steam turbine generator sets, large power grid systems, petrochemicals, aircraft and ship engines, automobiles, metallurgical equipment, mining equipment, and machine tools. We collaborated with a world-renowned electrical company to develop an ATV28 frequency converter fault diagnosis system based on Agent technology, according to the requirements for whole-machine fault diagnosis of their ATV28 series frequency converters. 1. ATV28 Frequency Converter and its Fault Diagnosis Variable frequency speed control, as a reliable system, has been widely used in various speed control transmission devices. The replacement of DC speed control devices by frequency converters has become an inevitable trend, and the use of frequency converters in some production machinery has become a sign of the upgrading of these machines. Variable frequency speed control has advantages such as wide speed range, high precision, high efficiency and power factor, good reliability, convenient operation, and easy interface with other equipment. The ATV28 series frequency converter is a frequency converter for three-phase asynchronous motors, which can meet the requirements of most electrical drive applications and the needs of upgrading and retrofitting old equipment. The main application areas include fans, air conditioning equipment, pumps, compressors, conveyor belts, boxing and packaging machinery, etc. The frequency converter has complete protection functions, with undervoltage protection at the power input and grounding protection, short circuit protection, overcurrent protection, and system overheat protection at the output. The ATV28 frequency converter has 17 specifications, with AC rated input voltages of single-phase 200V, three-phase 200V, and three-phase 400V. It can also operate at AC voltages of single-phase 220V, three-phase 220V, and three-phase 380V (China's power grid voltage). The frequency converter output power has 10 levels: 0.37, 0.75, 1.5, 2.2, 3.0, 4.0, 5.5, 7.5, 11, and 15kW. To implement the computer diagnostic system for the ATV28 frequency converter, the following problems need to be solved: (1) Solving the uncertainty problem of software flow. Unlike production process control, fault diagnosis has many uncertainties: the test process, test methods, use of test instruments, and test results are all highly uncertain, making software design and maintenance very difficult. (2) The problem of enabling multiple instruments to work together. There are many types of instruments used in the fault detection of frequency converters (such as digital oscilloscopes, spectrum analyzers, KE2000 multimeters). They are all two-point (measurement signal) inputs and can only measure local single signals (such as current value, voltage value, resistance value, etc.). However, the fault diagnosis of frequency converters requires multi-point measurement (sometimes dozens of points need to be measured at the same time). It is necessary to realize the collaborative work of multiple instruments and data (measurement value) sharing. [b][align=center]For details, please click: Application of Agent Technology in Frequency Converter Fault Diagnosis System[/align][/b]