With reference to the chassis size and power matching parameters of Sichuan Automobile Industry Group Corporation (hereinafter referred to as Chuanqi) and the power performance of existing electric vehicles, the power performance of the entire vehicle is drawn up. Adopt the design principle of light weight, use aluminum alloy body, light solar panels and batteries, adopt the integration technology of solar energy components and body to reduce the weight of the whole vehicle to 850kg, and strive to increase the speed to 40km under the power condition of 4kW /h; Optimized design with standardized components to achieve better cost performance and facilitate the upgrade of existing electric vehicles to solar electric work vehicles, similar to passenger vehicles, and multi-purpose solar electric vehicles can be developed on this basis.
- Multi-purpose vehicle design
(1) Dynamic parameter selection. According to the above principles, the dynamic parameters are selected as shown in Figure 1, and the design is based on this.
(3) Structural design of solar electric vehicle. The structure of the car is shown in Figure 2. Its structure is mainly the underframe structure for load-bearing and traction and the box structure for fixing solar panels. High-speed trains have all adopted aluminum alloy welded structures, and have formed standard hollow flat profiles, but the car structure is basically a frame structure, which is difficult to achieve. To ensure the strength of the welded joint and the base metal, the integral joint member is inserted into the plum head and bolted.
- Analysis of aluminum alloy structure
(1) Strength calculation
The finite element analysis software Abaqus is used to calculate the strength of the car body, and the gravity of the solar panels on both sides is simplified into a downward load (the roof is 800N and the body is 400N). onto the hinges of the body frame. Through the calculation, the stress load and deformation of the body frame are obtained as shown in Figure 3.
According to Figure 3 (a) and (b) the stress and deformation are concentrated in the underframe longitudinal beams, especially the three longitudinal beams in the middle of the two girders, the maximum stress value is 145.9MPa, and the maximum displacement occurs in the roof beam with a size of 2.618mm , but also within the allowable range, to meet the force load conditions.
(2) Design optimization
In order to make the car body as lightweight as possible, optimization was carried out according to the stress diagram and displacement diagram, appropriately reducing the trusses that bear less load, and shortening the length of the side longitudinal beams at the four corners of the underframe to reduce the torque. Import it into Abaqus again and repeat the calculation of the above steps, and obtain the force load and displacement of the body frame as shown in Figure 3(c) and (d), the maximum stress value is 138.8MPa, and the maximum displacement is 2.406mm.
(3) Overload inspection
When the construction vehicle is working on the construction site, unexpected situations such as sudden overload will occur. In order to verify the reliability of the vehicle body, it is analyzed whether the vehicle body can meet the strength and stiffness requirements in the event of a temporary ultra-high overload and other sudden conditions. In the optimized finite element model, the load is increased to 1200N, 800N and 8000N respectively. The overload force and deformation obtained by the analysis are shown in Figure 3(e) and (f), the maximum stress value is 207.1MPa, and the maximum displacement is 3.651mm, which is still within the allowable range, and the design results meet the specifications and usage requirements.
(4) Optimization effect
After optimization, the maximum stress is reduced from 145.9MPa to 133.8MPa, a reduction of 8%; the deformation is reduced from 2.618mm to 2.406mm, a reduction of 8.1%; 11% body weight loss.
- Solar multi-purpose electric vehicle manufacturing
(1) Structural parameters of the original multi-purpose electric vehicle
The overall structure of the original design and the selection and calculation results of power parameters are shown in Figure 4(a). The transmission part uses a 48V/4kW brushless motor and differential steering system for general electric vehicles.
(2) Structural parameters of the new car
Due to the nature of the initial trial car and the limitation of funds, the body of the car was changed from an aluminum alloy structure to a steel structure. Polycrystalline silicon semi-flexible PC board is used, and the half side wall can be opened and monocrystalline silicon flexible board is used), the power is increased from the original design 1.92kW to 2.2kW, and the mass of the solar panel is reduced from 160kg to 32kg. The motor power of the developed car is too big for the car, and the normal speed can only reach 12km/h, and the maximum is 15km/h. The increased capacity of photovoltaics and batteries can extend the working time of vehicle and welding.
According to the test results and theoretical calculations, it is consistent with the design using an aluminum alloy structure and a 4kW motor with a speed of 40km/h. For the convenience of comparison, a solar electric vehicle with the same material, the same power system and power but light weight was rebuilt to verify the variation law between power-weight-vehicle speed. The structure and technical parameters of the two vehicles are shown in Figure 5.
(3) Electric vehicle structure manufacturing
Assemble the front and rear axles on a welded channel steel frame, then weld the bottom frame, the cab frame and the equipment mounting bracket according to the size of the container solar car body, then lay the floor, install the electrical control and operation equipment, and use the battery as the power source. Can be made into electric flat car. Since the original designed aluminum alloy is changed to a steel structure, the manufacturing process is much simpler, the steel structure is easy to obtain, the strength of the welded joint is easy to achieve equal strength, and the cost is the lowest. The manufacturing process and operation are shown in Figure 6.
(4) Manufacturing from electric vehicles to solar electric vehicles
On the basis of the above electric vehicle, the main structure of the solar electric vehicle is completed by welding the steel frame and wall panels that are compatible with the solar panel, as shown in Figure 7(a). The size of the box is 4×2×2m, and 8 pieces of 1×1m/150W semi-flexible polysilicon PC boards are arranged on the roof, which can output 1200W solar energy; 4 pieces of 1.6×0.8m/250W flexible monocrystalline silicon imported solar energy are arranged on the side, which can output solar energy 1000W; the total output solar energy is 2200W. If a 250W or 300W solar panel is arranged at the slant glass of the cab, the solar energy output of 2450W or 2500W can be obtained. After manufacturing, the appearance and interior of the vehicle are shown in Figure 7(b) and Figure 7(c), and the running state of the vehicle is shown in Figure 7(d).
(5) Vehicle material devices and quality. A summary of the specifications and quantities of materials and components used in the vehicle is shown in Figure 8. The mass of the vehicle is increased from 815kg to 1400kg.
- Solar multi-purpose electric vehicle
Based on the solar electric vehicle, the basic equipment in the vehicle is adjusted to meet various needs, that is, it becomes a multi-purpose solar electric vehicle.
(1) Solar welding engineering vehicle. The car is designed with two iron cabinets as workbenches and storage cabinets, for example, as a welding engineering vehicle. The existing 5kW·h battery can drive various welding machines, and the iron cabinet plane and the other half-empty car can be used as work sites.
(2) Expansion of solar electric utility vehicles. As shown in Figure 9, as long as 8 foldable furniture 350×950mm benches, 8 350mm square benches, and 1 800mm square table are added, various combinations can be arranged into various special vehicles.
(3) Expansion of solar electric utility vehicles. The design and manufacture of the solar car body of the current car has been greatly improved from the original container solar car body, but the speed is too low, and the equipped battery can be used by low-power welding equipment. It can be charged according to the output capacity of 2.5kW solar energy of the current car, and can be equipped with at least 12kW·h battery to work, which can drive larger welding equipment or other working equipment to become various engineering vehicles. However, to increase the speed of the vehicle, the power of the motor must be increased. For example, if the original 4kW motor is replaced, the speed can be increased to 30km/h. If the car body is changed to an aluminum alloy structure, the speed can reach 40km/h, which is consistent with the original design. Since the frictional resistance of the rail car is much smaller than that of the wheeled car, if it is changed to a rail car, it is expected that the speed can be increased to 70km/h, which is equivalent to the speed of the current tram.
- Record and analysis of solar electric vehicle trial operation test
(1) Test process of solar welding engineering vehicle
Test location: Xipu campus of Southwest Jiaotong University; test time: 12:00 noon. Test steps: ① Fully charged, disconnect the solar charging device to start, the body vibrates, it is difficult to start, and the power display shows 80%; reverse the car about 50cm, and then move forward successfully, the temperature in the car is 40C, and the voltage is 48V. ②Driving 5km, the maximum speed is 14.3km/h, the driving speed is 10~12km/h; the power is 60%~70%. ③After 8km, when starting, the display power is 30%. After running smoothly, the power rebounds to 50%, and the maximum speed is 10km/h. ④After 9km, when starting, the display shows 10% power and the maximum speed is 9.5km/h. ⑤After 10.8km, the speed reduction is very obvious, and the speed is 6km/h. ⑥After 11.1km, the speed is very low, and the meter shows that the voltage is 41V. At 11.16km, the car stops moving forward, but at this time, the car can be reversed. With the help of manpower, the car body returns to the garage.
Conclusion: In the whole process, the average speed is 8.4km/h, the maximum speed is 14.3km/h, the time is 1.18h, and the mileage is 11.2km. After running smoothly, the power drops slightly, and the speed can also be maintained at 10~12km/h; after 8km, the power and speed drop significantly; when the car fails to start, there is still some power in the battery, this phenomenon should be related to the “small horse” Big car” is related.
Analysis of the operation test results of the self-made multi-purpose solar electric vehicle: The operation test results of the solar electric vehicle are shown in Figure 10(a). ① After a trial operation of 11.2km, the average speed is only 8.4km, and the normal and stable running speed is 10~12km/h. The top speed is 14.3km/h. ②The battery capacity drops a lot when accelerating, but it picks up when decelerating, and the capacity consumption is less at a constant speed, but when the capacity retention is less than 40%, it will not only reduce the vehicle speed, but also make the battery capacity decrease faster, so Frequent start-stop and low-capacity operation will increase energy consumption and shorten battery life. The use of super capacitors can reduce the energy consumption of frequent start-stop and stop, and use solar auxiliary power supply to make the battery always run under high-capacity conditions, which not only increases power supply and prolongs battery life. The continuation mileage of the vehicle can also prolong the service life of the battery, so the development of solar super capacitor vehicles and hybrid capacitor vehicles is the development direction.
If using the original design or changing to a rail car, the test results are shown in Figure 10(b), and it can be seen from the figure: ① According to the design formula, if the slope resistance, acceleration resistance and windward resistance are not considered, the power requirement is related to the vehicle weight (self-weight + load) is proportional to the speed of the vehicle. If the original aluminum alloy structure is used, the vehicle speed can be increased by 40% to 16.8km/h. ②If the motor power is 4kW, the speed can be increased by 1.7 times to 40km/h, which is in good agreement with the original design. ③If the structure of the car body remains unchanged, only the wheels are changed to steel wheel rail cars. Compared with the 11-seat electric sightseeing car and the rail flat car, the speed and dead weight of the car are the same, and the power requirement is 4/2.2, then the power requirement can be reduced by 45%. , or the speed increases by 45%, that is, 24km/h, and the ratio of the weight of the two is 2.8. Considering the reduction in mass, the speed is expected to increase to 60km/h, but this does not take into account the difference in load.
(2) Comparison of the new solar electric test vehicle and the current vehicle upgraded solar electric vehicle
The structure and test results of the new solar electric test vehicle are as described above. For further verification and comparison, an existing electric vehicle is added with a set of 100W solar panels and a controller to upgrade to a solar electric vehicle (existing electric vehicles developed by various manufacturers). The vast majority of solar electric vehicles are of this type), both of which have the same power, body material, drive motor and transmission structure. The modified vehicle is only smaller than the self-made vehicle, light in weight, and small in load capacity. The solar input is only 100W, which can only be used for The auxiliary power supply charges the battery, increasing the cruising range and prolonging the life of the battery. Due to the large size and quality of the new car, the motor power is small, and the output of solar power is greater than that of the motor, so it can run at low speed with all solar energy. If it is equipped with enough batteries, it can drive electric vehicles of more than 10kW or welding equipment.