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Solar panels inverter systems control scheme is: photovoltaic battery converse solar energy into electrical energy, and the series parallel tuned to DC voltage which meet the SPWM inverter, through inverter and filter inductor formed and grid voltage with the same frequency and phase of sinusoidal current, the realize the grid inverter using SPWM (sine pulse width modulation) inverter technology.
According to the periodic condition of power system, the following 3 conditions should be satisfied when the SPWM inverter circuit is connected to the grid:
1.In the renewable energy feedback system, the output voltage of the inverter is close to that of the city power, and the pressure difference should be less than 10%.
2.Inverter output frequency close to the frequency of the city power, the general frequency difference is not more than 0.4Hz.
3.Inverter output current and the city electric voltage phase is same, usually this phase difference should not exceed 10 degrees. PV grid connected inverter control is the key of the inverter design, the use of advanced control technology is the key technology to improve the performance of the solar inverter. With the high frequency of power electronic devices and the improvement of microprocessor operation speed, it is possible that some advanced control strategies can be applied to the photovoltaic grid connected control.

Improving the conversion efficiency of the solar inverter is the biggest problem in the solar photovoltaic power generation. Since the output volt ampere characteristic curve of photovoltaic array is nonlinear, and has a close relationship with the solar radiation intensity, environmental temperature, rain, fog and other weather conditions, with the different sunlight intensity and ambient temperature, its voltage is changed, the output power also produced very big change, so the solar cell is a unstable power supply. In order to output as much power as possible under the same conditions of sunlight and temperature, improving the efficiency of the system, the MPPT of a solar cell array is proposed. The use of MPPT in the system can improve the conversion efficiency of the solar inverter system, but also to play the greatest potential in the light output power of photovoltaic array for any sunlight intensity, make full use of solar power inverter output.

SSP3115C 1-12KVA Low Frequency Pure Sine Wave Inverter with MPPT Solar Charge Controller

MPPT Solar charge controller

MPPT Solar charge controller (12v mppt solar charge controller,24v mppt solar charge controller,48v mppt solar charge controller)

In general, the backup time of commercial UPS battery is not as long as in industrial applications, usually in the 10-30 minutes or so, the charging capacity does not require the capacity increasing design. UPS battery charger is generally designed to be able to back the lead-acid batteries, which back up time is 15-30 minutes, to the capacity of 95% in 8-10 hours.Compared with the commercial UPS, in industrial applications, charging capacity must have higher ability, because the battery backup time from 60 minutes to 8 hours or more, which requires the charger in the UPS system has enough battery recharge capacity. In many cases, the use of backup time for 4-8 hours of battery configuration. In the industrial field of UPS, in order to better adapt to the demand of high and low temperature environment, nickel cadmium batteries have been widely used, in addition to meet the industrial grade UPS charger for lead-acid batteries, also need to meet the charge and discharge characteristics of the nickel cadmium battery.

The main factor of a MPPT Solar charge controller is the comprehensive system of circuit protection function. This is a key role of the controller. The traditional common charge and discharge controller can only be used in general occasions. But the rationality of the design of the protection circuit, the selection of parameters is very important, and the rest is the actual precision of the controller.

Some customers are often found that after a period of time, especially after the continuous overcast and rainy days, the street lamps will be not bright for several days or even several days, while detect the voltage of battery is normal, controller and lights are no fault. This problem has let many developers doubt. Remove of other factors, then comes down to the controller, that is under voltage protection voltage parameters:
1.The value is set too high, the undervoltage recovery for longer time, also caused a lot of days are not light.
2.The parameter setting is reasonable, and the quality or the circuit design or the component selection of the cotroller which resulting in the distortion of the precision, leading to the aberration of the controller.

It is reasonable to set the general over discharge voltage to 12V, and be sure to choose a strong, reliable quality controller. In addition the battery plate configuration must be reasonable, if the daily charging amount of panels can not meet the power, put the battery in the depth of discharge if things often go on like this, life is greatly shortened.

1.The difference of circuit structure
Pure online UPS adopts double conversion on-line circuit structure, power input through AC/DC conversion, part of the power to charge the battery, most power converted to alternating current supply load. When the city electricity failure, UPS supply power to the load by the DC/AC conversion. When the UPS fails, it will automatically turn to bypass operation. Online interactive UPS using online interactive circuit structure, the city electrical input through the filter circuit to its surge suppression, filter output to the load, inverter as the charger to charge the battery at this time. When the city electricity failure, Online interactive UPS use the battery power output to the load converted by the DC/AC.

2.The difference of the application
On line interactive UPS provides high quality power protection for servers and network equipment. Pure online UPS in addition to the protection of the server and network equipment, but also for the communication system, automatic control equipment. Pure online UPS can also be compatible with cheap fuel generators.

3.Performance.
Compared with the online interactive UPS, pure online UPS has a higher performance of the voltage output, zero conversion time and a flexible installation of tower and rack converting.

On line interactive UPS using online interactive design, when supply power to the city power supply, the output voltage change with the market city power; when the city power voltage is too high or too low, the UPS start voltage regulation function, when supply power to the battery, the output voltage is sine wave, the default value is 230VAC, the user can choose 220VAC, 240VAC by software. Pure online UPS using pure online design, whether UPS run on city power or battery power, UPS output sine wave, the default value is 230VAC, the user can choose 220VAC and 240VAC by software.

Output voltage accuracy:
When the static state is 1%, while the dynamic state is 5%.
Output voltage distortion:
When the linear load is less than 3%, the nonlinear load is less than 5%.

When online interactive UPS in the city power failure, the battery power supply has a 2~4ms conversion time,while pure online UPS is 0ms.

Pure online UPS using tower frame type converse installation,which is very flexible, it can be installed in tower form. While increase the rack type conversion accessories, can easily converted into a rack mount UPS.