Field of Invention

[0001]
The present invention relates to a solar charged power system for vehicles and more particularly to an arrangement, which enables switching between a solar power source and other alternative power sources for battery charging of a hybrid power system for an automotive vehicle.

Description of Prior Art

[0002]
Depletion of non-renewable energy is fast catching up with our ever-growing energy needs. The impending crisis has shifted the focus of automobile makers to electric/hybrid vehicles. Electric vehicles are typically driven by charge stored in a battery, with the battery charged by an AC outlet plug in system. Hybrid vehicles are driven by a combination of a battery powered electric motor and a fuel burning internal combustion engine.

[0003]
Although an electric vehicle does not depend on burning fuels directly, they do use non-renewable sources like coal and other carbon based fuels for generation of electricity, which is used to charge the batteries. Solar energy is another conventionally used energy source for charging batteries in electric/hybrid vehicles. The development of unlimited, low cost and pollution free solar energy technologies will have multiple benefits in future when oil prices touch record high prices. A typical solar cell equipped vehicle for charging batteries, when parked in the sun, is much energy efficient than fixing the solar cells on stationary charging stations. Although the cost of installing the solar cells on a vehicle is substantial, its pay-back period is small, after which it literally comes free and without much maintenance. The constant charging of batteries using solar cells will increase the range of hybrid vehicles, for which they can go in electric mode, hence improving fuel economy. Further, solar cells can charge the battery of a hybrid vehicle in both of its running modes.

[0004]
However problem sets in when sunlight is not sufficient, for example during cloudy and rainy weather conditions, during night and the like. Under such weather conditions, performance of the vehicle maybe compromised if battery state of charge in not maintained within a desired range. It would therefore be very beneficial to have a switching means for hybrid vehicles which switches battery power source from solar cells to an alternate power such source such as magneto or regenerative braking.

Summary of Invention

[0005]
The present invention has been conceived in view of the following drawbacks in the prior art and it is the principle objective of the present invention to provide a switching means between a solar power source and an alternate power source, which ensures uninterrupted charging of vehicle battery. The solar charged power system as per the present invention comprises a series of comparators, a logic circuit, a first switch and a second switch. A solar power source is connected to a vehicle battery through the first switch and an alternate power source is connected to a vehicle battery through the second switch. The series of comparators compares the solar power source voltage and the vehicle battery voltage with certain preset reference voltages and provides input to the logic circuit. The logic circuit controls the first switch and the second switch based on inputs from the series of comparators and also based on certain predetermined conditions and

[0006]
The present invention ensures uninterrupted charging of the vehicle battery even during weather conditions unfavorable for solar power generation. Hence fuel efficiency and range of the vehicle is maximized.

[0007]
These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, the appended claims and the accompanying drawings. This summary is not intended to limit the scope of the claimed subject matter.

Brief Description of Drawings

[0008]
The above and other features, aspects, and advantages of the present invention are further illustrated by the accompanying drawings. The drawings are given by way of illustration only and are not limitative of the present invention. A brief description of the drawings is as follows: Fig. 1 is a side view of a conventional three-wheeled vehicle. Fig. 2 is an isometric view of a conventional three-wheeled vehicle. Fig. 3 is a block diagram of the present invention.

Detailed Description of Invention

[0009]
The present invention is hereinafter described with reference to the accompanying drawings. It is to be noted that like reference numerals designate corresponding or identical elements throughout the various drawings. The terms front and rear, and left and right as used indicate the front and rear and the left and right directions when viewed by a rider seated on a vehicle seat. For the sake of explanatory convenience, the present invention will be described as being embodied in a three-wheeled vehicle.

[0010]
Fig. 1 illustrates a side view of a conventional three-wheeled vehicle. A driver's cabin 13, which is open from both sides, enables the driver to enter and exit the vehicle. The driver's cabin 13 is provided with a driver's seat 15 and a handlebar 14. Control means for operation of clutch, gear, throttle etc. is provided on the handlebar 14. The vehicle has a front wheel 10 and two wheels 11 at the rear. The vehicle further has a passenger compartment 16 with a passenger seat 17. A power unit is generally mounted on a chassis 19 near the axis of the rear wheel 11. The power unit is provided with a lockabie access door 18 on the vehicle.

[0011]
Fig. 2 is an isometric view of a conventional three-wheeled hybrid vehicle having thin film flexible solar cells 20 installed on its roof. The thin film solar cells are made on polymer substrate and are glued to the canvas roof of the vehicle. The thin film flexible solar cells 20 are configured to convert solar energy into electrical energy and generate a solar cell voltage Vs.

[0012] Fig. 3 is a block diagram of the solar cell charged power system as per the present invention. As shown, the solar cell system which generates the solar cell voltage Vs is connected to the vehicle battery 27 through a first switch 26 and an alternate power source which generates an alternate source voltage VA is connected to the vehicle battery 27 through a second switch 25. A logic circuit 24 that receives inputs from a series of comparators selectively controls the first switch 26 and the second switch 25. The logic circuit 24 can be a combination of logic gates or a micro controller. The series of comparators consists of a first comparator 21, a second comparator 22 and a third comparator 23. The first comparator 21 compares the solar cell voltage Vswith a first reference voltage Vm. The second comparator 22 compares the first reference voltage Vm with a vehicle battery voltage VB. The third comparator 23 compares the vehicle battery voltage VB with a second reference voltage VR2. The first reference voltage Vm is the equal to the voltage when the vehicle battery is fully (100%) charged. The second reference voltage VR2 is equal to the voltage when the vehicle battery is 25% charged.

[0013]
The logic circuit 24 controls the first switch 26 and the second switch 25 based on the conditions given below in Table 1. The first switch 26 is turned on and the vehicle battery 27 is charged by solar cell voltage Vs if, as a result of the comparison performed by the first comparator 21 and the second comparator 22, the solar cell voltage Vs is greater than the first reference voltage Vm and the battery voltage VB is greater than the second reference voltage VR2. The second switch 25 is turned on and the alternate source voltage VA generated by the alternate power source charges the vehicle battery 27 if, as a result of the comparison performed by the first comparator 21 and the second comparator 22, the solar cell voltage Vs is lesser than the first reference voltage VRI and the battery voltage VB is lesser than the first reference voltage VR1. Both the first switch 26 and the second switch 25 is turned on, and the solar cell voltage Vs and the alternate source voltage VA charges the vehicle battery 27 simultaneously if, as a result of the comparison performed by the first comparator 21 and the third comparator 23, the solar cell voltage Vs is greater than the first reference voltage VRI and the battery voltage VB is lesser than the second reference voltage VR2.

Table 1

[0014]
Therefore, the logic circuit 24 enables the alternate power source to charge the vehicle battery 27 when generation of solar cell voltage Vs falls below a threshold voltage (VR1). Therefore when solar energy is insufficient, the present invention switches from the solar power source to an alternate power source such as magneto. Whenever the vehicle battery voltage VB falls below a threshold voltage (VR2), both Vs and VA are jointly employed to charge the vehicle battery 27. In addition to charging the vehicle battery 27, the present invention can also be used to power vehicle loads such as headlamp and parking lamps. Hence range of the vehicle while it runs on electric mode, is enhanced. Consequently fuel efficiency is increased.

[0015]
The foregoing description is a specific embodiment of the present invention and has been described for the purpose of illustration only. Persons skilled in the art may practice numerous alterations and modifications of the present invention without departing from its spirit and scope. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim:

1. A method of controlling a solar cell charged power system for vehicles comprising:

a) a first step of comparing a solar cell voltage Vs with a first reference voltage VR1;

b) a second step of comparing a vehicle battery voltage VB with the first reference voltage Vm;

c) a third step of comparing the vehicle battery voltage VB with a second reference voltage VR2;

d) a fourth step of charging a vehicle battery using the solar cell voltage Vs by turning on a first switch 26 if, as a result of the comparison at step (a) and step (c), the solar cell voltage Vs is greater than the first reference voltage VR1 and the battery voltage VB is greater than the second reference voltage VR2;

e) a fifth step of charging the vehicle battery using the solar cell voltage Vs and an alternate source voltage VA by turning on the first switch 26 and a second switch 25 if , as a result of the comparison at step (a) and step (c), the solar cell voltage Vs is greater than the first reference voltage Vm and the battery voltage VB is lesser than the second reference voltage VR2; and

f) a sixth step of charging the vehicle battery using an an alternate source voltage VA by turning on a second switch 25 if, as a result of the comparison at step (a) and step (b), the solar cell voltage Vs is lesser than the first reference voltage Vm and the battery voltage VB is lesser than the first reference voltage VR1;

2. The method of controlling a solar cell charged power system for vehicles as claimed in claim 1, wherein the first reference voltage VRI is equal to the voltage of the vehicle battery when fully charged and the second reference voltage VR2 is equal to the voltage of the vehicle battery when it is 25% charged.

3. A solar cell charged power system for vehicles comprising:

a solar cell system installed in a vehicle, the solar cell system configured to convert solar energy into electrical energy and generate a solar cell voltage Vs, said solar cell system connected to a vehicle battery through a first switch 26; an alternate power source configured to generate an alternate source voltage VA, said alternate power source connected to the vehicle battery by a second switch 25; and a logic circuit 24 which selectively controls the first switch 26 and the second switch 25 based on inputs from a first comparator 21, a second comparator 22 and a third comparator 23 wherein input from the first comparator 21 is the result of comparison between the solar cell voltage Vs and a first reference voltage VRI, input from the second comparator 22 is the result of comparison between a vehicle battery voltage VB with the first reference voltage VR1 and input from the third comparator 23 is the result of the comparison between a vehicle battery voltage VB with a second reference voltage VR2.

4. The solar cell charged power system for vehicles as claimed in claim 3, wherein the logic circuit 24 is a combination of logic gates.

5. The solar cell charged power system for vehicles as claimed in claim 3, wherein the logic circuit 24 is a micro-controller.

6. The solar cell charged power system for vehicles as claimed in claim 3, wherein the first reference voltage Vm is equal to the voltage of the vehicle battery when it is fully charged and the second reference voltage VR2 is equal to the voltage of the vehicle battery when it is 25% charged.

7. The solar cell charged power system for vehicles as claimed in claim 3, wherein the alternate power source is a magneto.

8. The solar cell charged power system for vehicles as herein above described in the specification and illustrated in the accompanying figures.