Modern life is full of various electronic products, which make our life more convenient and colorful. And these electronic products are inseparable from the power source. The important power source in nowadays and future is solar energy. However Solar energy is a kindly of directly current(DC) power, meanwhile most of our appliances are AC power supply. Then we need a device to convert DC power into AC power, that is inverter—-a power adjustment device composed of semiconductors.
How does the inverter work?
It consists of a boost circuit and an inverter bridge circuit. The boost circuit boosts the DC voltage of the solar battery to the DC voltage required for inverter output control; the inverter bridge circuit converts the boosted DC voltage into an AC voltage of common frequency equivalently. The inverter is mainly composed of switching elements such as transistors. By regularly turning the switching elements on and off (ON-OFF) repeatedly, the output is converted from direct current to alternating current.
Of course, such an inverter output waveform simply generated by on and off loops is not practical. Generally, it is necessary to use high-frequency pulse width modulation to narrow the voltage width near the two ends of the sine wave, widen the voltage width in the center of the sine wave, and always let the switching element move in one direction at a certain frequency within half a cycle, thus forming a pulse wave column (pseudo sine wave). The pulse wave is then passed through a simple filter to form a sine wave.
what is the inverter advantages in the solar energy system?
The inverter not only has the function of DC to AC conversion, but also has the function of maximizing the performance of solar cells and the function of system failure protection.
1. Automatic operation and shutdown function
After sunrise in the morning, the intensity of solar radiation increases gradually, and the output of solar cells increases accordingly. When the output power required by the inverter is reached, the inverter starts to run automatically. After entering the operation, the inverter will monitor the output of the solar cell components all the time, as long as the output power of the solar cell components is greater than the output power required by the inverter, the inverter will continue to run; until the sunset stops, even if it is rainy The inverter also works. When the output of the solar cell module becomes smaller and the output of the inverter is close to 0, the inverter will form a standby state.
2. Maximum power tracking control function
The output of the solar cell module varies with the intensity of solar radiation and the temperature of the solar cell module itself (chip temperature). In addition, because the solar cell module has the characteristic that the voltage decreases with the increase of the current, so there is an optimal operating point that can obtain the maximum power. The intensity of solar radiation is changing, obviously the best working point is also changing. Relative to these changes, the operating point of the solar cell module is always at the maximum power point, and the system always obtains the maximum power output from the solar cell module. This kind of control is the maximum power tracking control. The biggest feature of the inverter used in the solar power generation system is that it includes the function of maximum power point tracking.
- 1. Direct current can be changed to alternating current through an oscillating circuit.
- The obtained alternating current is boosted through the coil (at this time, the obtained alternating current is a square wave).
- 3. Rectify the obtained alternating current to obtain a sine wave.