photovoltaic boost converter using arduino

1. 4. Proposed System

As mentioned earlier, the proposed boost converter is implemented in between a solar panel and load as shown in Figure 10. This system is able to deliver power with a constant output voltage of 24V without storage elements such as battery. Therefore, the converter is small and light weight. In addition to that, the system is able to attach directly to the solar panel as a single unit.

Figure 10 shows that power stage included switch SW, a fast switching type flyback diode D, an inductor L , and output capacitor C. The controlling stage consists of a PIC16F877 microcontroller with built-in analog-to-digital converter (ADC), a power MOSFET driver, and a voltage divider. The control strategy based on the flow chart in Figure 8 will be written and load into the microcontroller. Voltage divider resistors R1 and R2 will divide the output voltage to a suitable voltage range which is acceptable by the built-in ADC in the microcontroller. PIC16F877 will then perform calculation based on the control algorithm and produce a PWM signal with a set of duty cycle. The frequency of the PWM is programmable by PIC16F877. The PWM signal is then transmitted to power MOSFET in power stage through a power MOSFET driver to perform on and off state. The PIC16F877 microcontroller unit features an eight-bit, successive approximation ADC, used by the control program to measure signals required for the power flow control. The 10-bit resolution is adequate for the proposed design. Also, it features two PWM outputs with program-controlled duty cycle and 208.3 kHz maximum frequency when driven by the 20 MHz clock of the unit. The first PWM output is used to control switch SW in boost converter while the second PWM output can be used to control switch in auxiliary circuit such as zero voltage switching circuit and zero current switching circuit to reduce switching losses in boost converter. This type of microcontroller was chosen because it has the necessary features for the proposed design such as built-in ADC, PWM outputs, eight-bit architecture, high clock rate, low power consumption and low cost. In order to calculate the value for Lmin and Cmin, the switching frequency will be set to the lowest value of 20 kHz. The rating of the proposed converter will be 100W and 24V output. By referring to (3), Lmin maximum will occur at k = 0.333 and the calculated value will be 2.1 mH. As the desired output voltage ripple factor is below 1%, the calculated value of Cmin will be 687μF. PIC16F877 microcontroller uses 5V as its reference voltage for the ADC. Therefore, the ADC should sense less than 5V from the voltage divider. The converter switching frequency and the inductance value is compromised between the converter’s efficiency, cost, power capability and weight.

For the control system, PIC16F877 microcontroller will produce a PWM signal pulse train with

varying duty cycle in the range of 0 to 1.0. Practically, duty cycle for boost converter is only in the range of 0 to 0.75. This is due to instability of boost converter (Mahmood et al., 2008). Therefore, the range of the input voltage for the boost converter is in the range of 6V and 24V. If the voltage detected is not within the range, PIC16F877 microcontroller will put the whole system into sleep mode. In order to control the duty cycle, voltage divider divides the output voltage of 24V to PIC reference voltage of 5V because ADC in PIC16F877 microcontroller is unable to operate under high voltage. The resistance of R1 and R2 should be high enough in order not to produce high power losses, I2R and affect the overall converter performance. Furthermore, as the reference voltage of PIC16F877 microcontroller is 5V, the PWM signal pulse train with the amplitude of 5V is unable to switch the power MOSFET on and off. Therefore, a current sink and source power MOSFET driver is needed to operate the power MOSFET as a switch working in the active region of its I-V characteristic.

Inresting text, what is its source, please?

Yes, I can UTFG, but better is if source link is included.

www.eurojournals.com/ejsr_41_1_05.pdf

it is a microcontroller based boost converter for photovoltaic systems.

what can u guys help me with

www.eurojournals.com/ejsr_41_1_05.pdf

it is a microcontroller based boost converter for photovoltaic systems.

what can u guys help me with

thank you.