Significance of HAPS Energy Era 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 ability consumption of the motors is easy, predicting the ability technology of photo voltaic cells is complicated. The solar always modifications its angle, the set up angles of the photo voltaic cells on the plane floor differ, and the complete HAPS performs a three-axis rotation (yaw, roll, and pitch). If the predictions are inaccurate and power runs brief, it turns into tough to keep up service and the altitude of the plane, posing vital dangers. Due to this fact, enhancing the accuracy of energy technology simulations is essential.
SoftBank is creating 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 cellular simulation fashions with SoftBank’s information of the stratospheric setting 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 consequences of self-shadowing. This enables for exact calculation of insolation and power steadiness throughout HAPS flights.
Stratospheric Gentle Supply Mannequin
The precise information exhibits that the photo voltaic spectrum at an altitude of 18-24 km, the place HAPS flies, typically matches the Air Mass 0 (AM0) in area. Nevertheless, this solely holds true throughout instances when the solar is at a excessive altitude; vital discrepancies come up when the solar is at a decrease altitude. To handle this, now we have developed a lightweight supply mannequin that may simulate the stratospheric setting 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 instances. Though parameter changes have been difficult resulting from stratosphere-specific phenomena throughout low photo voltaic altitude intervals, we efficiently developed a lightweight supply mannequin that intently aligns with precise measurements throughout all latitudes, longitudes, altitudes, and instances.
3D Mesh Modeling
Primarily based on the dimensions of the photo voltaic cell modules on the plane, we mechanically allocate one mesh per module and calculate the ability 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 instances. 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 varied HAPS airframe shapes, together with tailless, single-wing, tandem-wing, balloons, and airships.
Improvement and Optimization of Algorithms
To precisely reproduce the ability technology of photo voltaic cells throughout HAPS flights, we developed algorithms utilizing tensors, matrices, and vectors in 3D area. These algorithms account for atmospheric strain, air parameters, and reflections from the bottom and clouds, mechanically 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 will 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 exhibits the cumulative energy technology of the photo voltaic cells on the HAPS wing floor below sure circumstances. For photo voltaic cells put in flat on the bottom, the cosine losses are the identical whatever the route relative to the photo voltaic altitude, leading to concentric contour traces. 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 traces are disrupted.
Within the each day insolation distribution, the modifications within the plane’s yaw, roll, and pitch have an effect on the output tendencies. We analyzed the insolation traits at particular factors (A, B, C, D) on the wing when the plane rotated 360 levels within the yaw route instantly after dawn. In consequence, the lower in energy technology resulting from self-shading created by the saddle-shaped floor was additionally reproduced.
Abstract and Future Prospects
HAPS is anticipated to be utilized in varied fields, together with communication, remark, and catastrophe response. To comprehend these functions, correct predictions of the power steadiness within the goal flight space are important.
The SoftBank analysis staff 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 concentrate on creating expertise to offer secure high-altitude communication companies.
Author：Kohei Okada