“Inverters are commonly used Electronic devices. In the electronics industry, inverters are even more popular. For the inverter, the editor also introduced it in previous articles. The basic concepts of inverters, single-phase inverters, grid-connected inverters, etc., are all introduced by the editor. In order to improve everyone’s understanding of the inverter, this article will explain the common faults of the inverter.
Inverters are commonly used electronic devices. In the electronics industry, inverters are even more popular. For the inverter, the editor also introduced it in previous articles. The basic concepts of inverters, single-phase inverters, grid-connected inverters, etc., are all introduced by the editor. In order to improve everyone’s understanding of the inverter, this article will explain the common faults of the inverter.
1. What is an inverter
Inverter is a converter that converts DC power (battery, storage battery) into fixed-frequency, constant-voltage or frequency-modulated alternating current (usually 220V, 50Hz sine wave). It is composed of inverter bridge, control logic and filter circuit. It is widely used in air conditioners, home theaters, electric grinding wheels, electric tools, sewing machines, DVDs, VCDs, computers, TVs, washing machines, range hoods, refrigerators, video recorders, massagers, fans, lighting, etc. In foreign countries, because of the high popularity of automobiles, you can use inverters to connect batteries to drive electrical appliances and various tools to work when you go out to work or travel. The car inverter output through the cigarette lighter is 20W, 40W, 80W, 120W to 150W power specifications. A larger power inverter power supply should be connected to the battery through a connecting wire. Various electrical appliances can be used in the car by connecting household appliances to the output end of the power converter. The electrical appliances that can be used are: mobile phones, laptops, digital cameras, cameras, lights, electric shavers, CD players, game consoles, handheld computers, power tools, car refrigerators, and various travel, camping, and medical emergency appliances Wait. The inverter itself also consumes part of the electricity when it is working, so its input power is greater than its output power. The efficiency of the inverter is the ratio of the output power of the inverter to the input power, that is, the inverter efficiency is the ratio of the output power to the input power. If an inverter inputs 100 watts of direct current and outputs 90 watts of alternating current, then its efficiency is 90%.
2. Common faults of inverter
(1) Low insulation resistance
Use elimination method. Unplug all the strings on the input side of the inverter, and then connect them one by one. Use the function of the inverter to check the insulation resistance to detect the problem string. After finding the problem string, focus on checking whether the DC connector has a water-immersed short-circuit bracket. Or fusing to short-circuit the bracket. In addition, you can check whether the component itself has black spots burned at the edge, causing the component to leak electricity through the frame to the ground grid.
(2) Low bus voltage
If it occurs in the morning/night period, it is a normal problem, because the inverter is trying to limit power generation conditions. If it occurs in normal daylight, the detection method is still the elimination method, and the detection method is the same as item 1.
(3) Leakage current failure
If the leakage current is too large, remove the input terminal of the PV array, and then check the external AC grid. The DC and AC terminals are all disconnected, and the inverter will be powered off for 30 minutes. If it can be restored by itself, continue to use it. If it cannot be restored, then To contact a professional engineer.
(4) DC overvoltage protection
As components pursue high-efficiency process improvements, power levels continue to update and rise, while component open-circuit voltage and working voltage are also rising, temperature coefficient issues must be considered at the design stage to avoid overvoltage at low temperatures causing hard damage to the equipment.
(5) The inverter does not respond when starting up
Please make sure that the DC input circuit is not reversed. Generally, the DC connector has a fool-proof effect, but the crimping terminal has no fool-proof effect. It is important to read the inverter manual carefully to ensure the positive and negative poles before crimping. The inverter has built-in reverse connection short-circuit protection, and it will start normally after normal wiring is restored.
(6) Grid failure
The preliminary survey of the power grid heavy load (large power consumption working hours)/light load (less power consumption rest time) is reflected here, and the health of the grid-connected point voltage is investigated in advance, and the grid situation is communicated with the inverter manufacturer. The combination of technology can ensure that the project design is within a reasonable range, especially for rural power grids. Inverters have strict requirements on grid-connected voltage, grid-connected waveform, and grid-connected distance. Most of the grid overvoltage problems are caused by the light load of the original grid. If the voltage exceeds or is close to the safety protection value, if the grid-connected line is too long or the crimping is not good, the line impedance/inductance is too large, the power station will not be able to operate normally and stably.