3 Factors Affecting the Service Life of a Power Inverter
The power inverter converts the DC power (battery and battery bank) into AC power. It’s widely used in the mobile phone, notebook PC, digital video camera, camera, headlamp, electric shaver, CD player, recreational machine, palm computer, power tool, car refrigerator and various emergency electrical apparatus used in the tourism, camping and medical treatment. Then what are the factors affecting the service life of the power inverter? Next we will deeply analyze the factors that affect the service life of the power inverter, including the device lifetime, design and installation.
In the broad sense, the inverter is a switching mode power supply, so its components can be basically divided into resistor, capacity, diode power devices (IGBT or MOS tubes), inductor and transformer, current sensor, IC, optocoupler and relay.
Generally, service life of the resistor, chip capacitor and ceramic capacitor can be more than 20 years. Theoretically, the inductor and transformer are defaulted to work for long time without failure on the design if only not exceeding the material temperature. Diodes and triodes with small power can work more than 100 thousand hours basically. The mechanical life of the relay is generally more than 1 million times and the electrical life is more than 10 thousand times. Generally, power device IGBT or MOS do not consider the life as long as they meet design specifications. The fan and fuse are vulnerable components, but they will not affect the service life of the inverter, as they can be replaced as long as they break; service life of the film capacitor is more than 100 thousand hours and that of electrolytic capacitor is 2000-3000H at 105℃, the service life may also be 5000-6000H, and it doubles as the temperature decreases 10℃. Therefore, the weakest device of the inverter lies in the service life of the electrolytic capacitor.
Device lifetime is the basic factor to ensure the service life of the inverter, while excellent design is the key factor to ensure the service life of the power inverter. Then what design factors will seriously affect the service life of the inverter without being detected in a short time?
Temperature is one of the important factors affecting the service life of inverter, particular for the electrolytic capacitor and optocoupler, service life of the electrolytic capacitor reduces by half as the temperature rises by 10℃. Too high temperature also accelerates the light failure of the optocoupler and IGBT is usually driven by optocoupler, so the failure of optocoupler will lead to the damage of IGBT.
The service life of a relay can be 1 million times at zero current switching, however, its service life almost exponentially decays as the increase of current at switch time, keeping a zero current switching of a relay with precise software control is the key factor to ensure the relay life.
The power inverter generally works in bad environment and many affecting factors exist, such as poor power grid quality, large local perceptual load. If the inverter protection function and EMC are not well designed, it will be easily affected by external factors. Once the IGBT driven is interfered, it’s easy to lead the erroneous trigger and machine explosion.
Although the group series inverter has a protection level of IP65 and it can be installed both indoor and outdoor, the installation environment still has great influence on the service life of the inverter. If the inverter is installed in a direct sunlight, humidity, high acidity and alkalinity environment, its service life will reduce. Moreover, working in sunlight directly may cause the inverter to overheat and reduce load, thus affecting the generating capacity. Therefore, it’s also a key factor to ensure the service life of inverter choosing a suitable installation environment.