The article explains a dual input hybrid solar and wind battery charger circuit using cheap and ordinary components. The idea was requested by one of the interested members of this blog.
The Circuit Request
Good after noon sir am designing a " Solar and Wind energy harvest regulator circuit" which has two inputs and one output.
The PV solar panel ( 0-21V DC) and the other input is a wind turbine (15V DC).
The circuit must be designed for charging a 12v battery . the output current being delivered to the loaded battery must not deliver more than 3.5A.
My group and myself have gotten a few circuits off the internet and simulated them using pspice none of them is giving us the output current of 3.5 A. please sir can you please help us with examples of circuits which we can use.
The Circuit Design
In one of my previous posts I introduced a similar concept which enabled a battery to be charged from two sources of energy such as wind and solar simultaneously and without the need of any manual intervention.
The above design is based on PWM concept and therefore could be a bit complex and difficult to optimize for a layman or a new hobbyist.
The circuit presented here offers exactly the same features, that is, it enables the charging of a battery from two different sources, yet keeping the design extremely simple, efficient, cheap and hassle free.
Let's understand the circuit in details with the help of the following explanation:
The figure above shows the proposed solar, wind twin hybrid battery charger circuit, using very ordinary components such as opamps and transistors.
We can see two exactly similar opamp stages being employed, one on the left side of the battery and the other on the right side of the battery.
The left side opamp stage becomes responsible for accepting and regulating the wind energy source while the right side opamp stage processes the solar electricity for charging the single common battery in the middle.
Although the two stages look similar, the modes of regulation are different. The wind energy controller circuit regulates the wind energy by shunting or shorting the excess energy to ground, while the solar processor stage does the same but by cutting of the excess energy instead of shunting.
The above explained two modes are crucial since in wind generators which are essentially alternators require the excess energy to be shunted, and not cut off, so that the coil inside can be safeguarded from over current, which also keeps the speed of the alternator at a controlled rate.
This implies that the concept can be also implemented in ELC applications also.
How the opamp is Configured to Function
Now let's investigate the functioning of the opamp stages through the following points:
The opamps are configured as comparators where the pin#3 (non-inverting input) is used as the sensing input and pin#2 (inverting input) as the reference input.
The resistors R3/R4 are selected such that at the required battery charging voltage, pin#3 just becomes higher than pin#2 reference level.
Therefore when the wind energy is applied to the left circuit, the opamp tracks the voltage and as soon as it tries to exceed the set threshold voltage, pin#6 of the IC goes high which in turn switches ON the transistor T1.
T1 instantly short circuits the excess energy restricting the voltage to the battery at the desired safe limit. This process goes on continuously ensuring the required voltage regulation across the battery terminals.
The opamp stage at the solar panel side also implements the same function however here the introduction of T2 makes sure that whenever the solar energy is higher than the set threshold, T2 keeps on cutting it OFF, thereby regulating the supply to the battery at the specified rate, which safeguards the battery as well as the panel from unusual inefficient situations.
R4 on both the sides may be replaced with a preset for facilitating easy setting up of the threshold battery charging level.
Parts list for the solar wind dual hybrid battery charger circuit
R1, R2, R3, R5, R6 = 10k
Z1, Z2 = 4.7V , 1/2 watt zener diode
C1 = 100uF/25V
T1, T2 = TIP147,
T3 = BC547
D2 = 1N4007
D1 = 10 amp rectifier diode or Schottky diode