The solar ac power system consists of solar panels, charging controllers, inverters and batteries. Solar dc power systems do not include inverters. The process of converting ac energy into dc energy is called rectification, the circuit that completes the rectification function is called rectification circuit, and the device that realizes the rectification process is called rectification equipment or rectifier. Accordingly, the process of converting the dc power supply to the ac power supply is called the inverter, the circuit to complete the functions of the inverter is called the inverter, and the device to realize the inverter process is called the inverter device or inverter.
[2] the core of the solar inverter is the inverter switch circuit, referred to as the inverter circuit. The circuit completes the function of the inverter through the on-off of the power electronic switch. The on-off and off-off of power electronic switching devices require a certain drive pulse, which can be adjusted by changing the voltage signal. The circuit that generates and modulates the pulse is usually called a control circuit or control circuit. The basic structure of the inverter device, in addition to the inverter circuit and control circuit, there are protection circuit, output circuit, input circuit, output circuit, etc.
Due to the diversity of buildings, it will inevitably lead to the diversity of solar panel installation. In order to maximize the conversion efficiency of solar inverters, we need to diversify our inverters to achieve the best way to convert solar energy.
Output waveform classification
(1) square wave inverter square wave inverter output ac voltage waveform is square wave. The inverter circuit used by this kind of inverter is not exactly the same, but the common characteristic is that the circuit is relatively simple, the number of power switch tube used is very small. The design power is generally between 100 watts and kilowatts. The advantages of square wave inverter are: simple line, cheap price, convenient maintenance. The disadvantage is that due to the large number of high harmonics in the square wave voltage, additional losses will be generated in load appliances with core inductors or transformers, which will interfere with radios and some communication equipment. In addition, this kind of inverter has voltage regulation range is not wide enough, the protection function is not perfect, the noise is relatively large and other shortcomings.
(2) step-wave inverter the output ac voltage waveform of this type of inverter is step-wave. There are many different lines of step-wave output realized by the inverter, and the number of steps of output waveform varies greatly. The advantage of the step-wave inverter is that the output waveform such as the wave is obviously improved, the content of high harmonics is reduced, when the step-wave reaches more than 17, the output waveform can realize the quasi-sinusoidal wave. When the transformer is not used, the efficiency of the whole machine is very high. The disadvantage is that the ladder wave stack circuit USES more power switches, some of which require multiple sets of dc power input. This brings trouble to the grouping and wiring of solar cell array and the balanced charging of battery. In addition, the step-wave voltage still has some high frequency interference to the radio and some communication equipment.
(3) sine wave inverter sine wave inverter output ac voltage waveform for sine wave. The advantages of sinusoidal inverter are that the output waveform is good, the distortion is very low, the radio and equipment interference is small, low noise. In addition, the protection function is complete, the machine efficiency is high. Disadvantages: the circuit is relatively complex, high technical requirements for maintenance, the price is more expensive. The classification of the above three types of inverters is conducive to the identification and selection of inverters by designers and users of photovoltaic systems and wind power generation systems. In fact, the same waveform of the inverter in the line principle, the use of devices and control methods and so on are still very different.