The AC voltage waveform of square wave inverter is square wave. The circuits used in such inverters are not exactly the same, but the common characteristic of them is that the circuits is relatively simple, and use a small number of power switches. The power is generally designed between 100w to 1kw. Square wave inverter has the advantage of simple, cheap, easy to maintenance. The disadvantage is that due to the square wave voltage contains a large number of high harmonics, with iron core inductance or transformer load with electrical equipment will produce additional loss, and can interfere some communication equipment. In addition, this type of inverter has some other disadvantages such as the voltage regulation range is not wide enough, the protection function is not perfect, the noise is relatively large and so on.
Solar powered inverter not only has the function of direct AC conversion, but also has the fuctions of maximize solar cell and system maintenance. Here we introduce the functions of active operation and shutdown , and maximum power point tracking briefly.
1.Active operation and shutdown After sunrise in the morning, the intensity of the solar radiation is gradually strengthened, and the output of the solar cell increases. When the output power of the inverter is reached, the solar powered inverter is active. After entering the operation, the inverter will always look after the output of the solar cell module, as long as the output power of the solar cell component is greater than the output power of the inverter need, the inverter will continue to run; until sunset, the inverter shut down. The solar powered inverter can run even if the rainy day. When the output of the solar cell module becomes smaller, the output of the inverter is close to 0, the inverter will enter the standby mode.
2.Maximum power point tracking(MPPT) The output of the solar cell module is changed with the solar radiation intensity and the temperature of the solar cell component itself (chip temperature). Because other solar cell module has the characteristic of the voltage decreases with the increase of current, thus has the best task point can reach the maximum power. The intensity of solar radiation is always changing, and the most obvious point is in the transition. With regard to these changes, make the solar cell components always reach the task point at the maximum power point, the system obtain maximum power output from the solar battery components, this control is the maximum power point tracking. The biggest feature of the solar panel inverter is the maximum power point tracking (MPPT).
The solar module inverter links the each PV module to a inverter, while each component has a separate maximum power peak tracking, so that the PV module is better matched with the inverter. Usually used for 50W to the 400W photovoltaic power generation station, the total efficiency is lower than the string inverter. Since the communication is in parallel, this increases the complexity of the connection of the AC side, and difficult to maintain. Another problem need to be solved is that how to connected with power grid more effectively, the simple way is to connect directly through the common AC socket. Thus can reduce the cost and simplify the equipment installation, but usually the grid safety standards of different cities may not be allowed to do so, the power company may against power devices directly connect to ordinary home users’ sockets. Another security related factor is whether or not to use the isolation transformer (high frequency or low frequency), or to allow the use of non transformer type inverter. This inverter is widely used in glass curtain wall.
With the size of power supply cabinet, and then check the appearance of equipment, ensure matching wtih the selected support. A rugged cabinet can bearing weighing up to 450 pounds, so it is necessary to check the tools that handling equipment, such as lifting or trolley. The cabinet on wheels, so you only need to put the equipment installed in the power control cabinet, pushed to the right place. Measure the size of the room and the height of the ceiling, doors and lift to make sure that the cabinet can be passed. In addition, consider to the many types of equipment in the cabinet, to ensure that the power supply cabinet is near the power, network cable spigot and communication socket. Check the angle of power control cabinet door open and closed. Standard cabinet door open on the right and the hinge on the left, of course, does not rule out the opposite situation. All the doors and side panels should be easy to open, easy to maintain. When you want to install equipment power supply cabinet into an existing group, you can put the cabinet next to a row, looks safe and tidy. Some group due to various reasons, can not be increased, or only adding several accessories. The good cabinet model group should have full scalability, and with all the necessary hardware, remove the side panels of the power supply cabinet, connect the power control cabinet to each other in a row by screws.
The early period outdoor network enclosures are made mostly by casting or angle connected through the screw and rivet, or the welded into the frame of cabinet then install the door made of a thin steel plate. This kind of outdoor power enclosure has been eliminated as it is big, bulky and shabby appearance. With the use of transistors and integrated circuits, various components become super small, the structure of cabinet develop toward the direction of miniaturization and modularization. The outdoor network enclosure has developed from the past whole panel structure into a certain size series of plug box and plug in structure. The assembly arrangement of plug box and plug in is divided into horizontal and vertical arrangement. The materials of network cabinets commonly used thin steel plate,various shape of the steel or aluminum, and various engineering plastics etc.. The outdoor power enclosure frame network not only connected by welding and screws, but also bonding process.
