Significance of HAPS Energy Technology Simulation
(For a proof of HAPS power steadiness, click on right here)
To maintain a solar-powered HAPS flying constantly, its energy technology should exceed its consumption. Whereas predicting the facility consumption of the motors is easy, predicting the facility technology of photo voltaic cells is complicated. The solar consistently modifications its angle, the set up angles of the photo voltaic cells on the plane floor range, and the whole HAPS performs a three-axis rotation (yaw, roll, and pitch). If the predictions are inaccurate and power runs quick, it turns into tough to keep up service and the altitude of the plane, posing important dangers. Subsequently, enhancing the accuracy of energy technology simulations is essential.
SoftBank is growing a HAPS energy technology simulation mannequin in collaboration with Professor Nishioka’s laboratory at Miyazaki College, a nationwide college company. This simulation mannequin combines Miyazaki College’s experience in ground-based cell simulation fashions with SoftBank’s information of the stratospheric atmosphere and plane. It replicates the yaw, roll, and pitch actions of the plane and precisely predicts photo voltaic radiation utilizing a 3D mesh that considers the scattering of daylight and the results of self-shadowing. This enables for exact calculation of insolation and power steadiness throughout HAPS flights.
Stratospheric Gentle Supply Mannequin
The precise knowledge reveals that the photo voltaic spectrum at an altitude of 18-24 km, the place HAPS flies, usually matches the Air Mass 0 (AM0) in house. Nevertheless, this solely holds true throughout occasions when the solar is at a excessive altitude; important discrepancies come up when the solar is at a decrease altitude. To deal with this, we now have developed a lightweight supply mannequin that may simulate the stratospheric atmosphere on a pc, correcting for atmospheric scattering and absorption spectra.This mannequin permits us to calculate the photo voltaic spectrum and insolation for any given latitude, longitude, altitude, and time. Utilizing this mannequin to copy an altitude of 20 km, we discovered that the direct and scattered parts of sunshine differ from AM0 (1366W/㎡) by solely 1-2%, which is inside the measurement error of the sensors throughout excessive photo voltaic altitude occasions. Though parameter changes have been difficult as a result of stratosphere-specific phenomena throughout low photo voltaic altitude durations, we efficiently developed a lightweight supply mannequin that intently aligns with precise measurements throughout all latitudes, longitudes, altitudes, and occasions.
3D Mesh Modeling
Based mostly on the dimensions of the photo voltaic cell modules on the plane, we robotically allocate one mesh per module and calculate the facility technology for every mesh. The higher floor of the HAPS wing is saddle-shaped, and complicated self-shading happens, particularly throughout low photo voltaic altitude occasions. It’s essential to preemptively account for cosine losses and the presence of self-shading from gentle rays in all instructions. This mannequin has been designed to accommodate numerous HAPS airframe shapes, together with tailless, single-wing, tandem-wing, balloons, and airships.
Growth and Optimization of Algorithms
To precisely reproduce the facility technology of photo voltaic cells throughout HAPS flights, we developed algorithms utilizing tensors, matrices, and vectors in 3D house. These algorithms account for atmospheric stress, air parameters, and reflections from the bottom and clouds, robotically linking the photo voltaic irradiance mannequin with the photo voltaic cell modules on the wing floor. We additionally efficiently modeled the dynamic deformation of the wings. With these algorithms, we are able to effectively calculate the insolation acquired by HAPS photo voltaic cells and enhance the accuracy of the power steadiness throughout operations.
Simulation Outcomes
The next graph reveals the cumulative energy technology of the photo voltaic cells on the HAPS wing floor beneath sure circumstances. For photo voltaic cells put in flat on the bottom, the cosine losses are the identical whatever the course relative to the photo voltaic altitude, leading to concentric contour strains. Nevertheless, on the HAPS wing floor, when the photo voltaic altitude falls beneath 20 levels (roughly three hours after dawn and three hours earlier than sundown), these concentric strains are disrupted.
Within the day by day insolation distribution, the modifications within the plane’s yaw, roll, and pitch have an effect on the output traits. We analyzed the insolation traits at particular factors (A, B, C, D) on the wing when the plane rotated 360 levels within the yaw course instantly after dawn. In consequence, the lower in energy technology as a result of self-shading created by the saddle-shaped floor was additionally reproduced.
Abstract and Future Prospects
HAPS is predicted to be utilized in numerous fields, together with communication, commentary, and catastrophe response. To understand these purposes, correct predictions of the power steadiness within the goal flight space are important.
The SoftBank analysis crew plans to additional enhance accuracy by fine-tuning parameters, simulating all processes from takeoff to touchdown, and analyzing and modeling the transient facets of degradation throughout long-term operation. We’ll proceed to deal with growing expertise to supply secure high-altitude communication companies.
Author：Kohei Okada