High-power Solar Array Research Articles

High Voltage Solar Array Development for Space and Thruster-Plume Plasma Environments

High-power solar arrays are in development by the National Aeronautics and Space Administration (NASA) for near-term high-power solar electric propulsion (SEP) missions. These high-voltage (HV) solar arrays use deployable flexible blanket configurations and need to be able to operate in the plasma environment of high-power Hall thrusters operating at tens of kilowatts of power. Array voltages of 300–800 V are desired both to minimize the copper bus mass in the system and to potentially operate the SEP Hall thrusters directly at high specific impulse without an in- series power processing unit. Coupons with multiple strings of solar cells (SCs) have been tested to high positive and negative biases in a plasma environment representative of the edge of Hall thruster plumes. Proper encapsulation of the exposed metals and triple points is required to avoid excessive current collection and arc initiation. Fully encapsulated test coupons have been successfully been tested at highest anticipated thruster plume plasma densities at voltages from 600 to 1000 V, which enables both very high power arrays and direct drive configurations for SEP missions.

UI-RI Hybrid Lookup Table Method With High Linearity and High-Speed Convergence Performance for FPGA-Based Space Solar Array Simulator

Most existing high-power solar array simulators are suitable for simulating solar array energy sources in terrestrial applications. However, they are not sufficiently fast for spacecraft power-system testing using terrestrial testing applications. This paper proposes a UI-RI hybrid lookup table method with high linearity and high-speed convergence performance, which outperforms the traditional single UI lookup table method by employing a field-programmable gate array digital I–V outer loop. The proposed method overcomes the difficulty in guaranteeing stable output characteristics of the current output-type space solar array simulator (SSAS) because of the nonlinear I–V curves and slow convergence speed to the target operating point of the latter. The new lookup method is applied to a 2.4-kW hardware power platform of SSAS, and the SSAS can quickly respond to a load step between the short-circuit and open-circuit (OC) states, which is the harshest working condition, using the UI-RI hybrid lookup table method with a shunt switching frequency of 2 kHz. It can also quickly respond to a load step between the OC and rated-load states using a series-switching frequency of 10 kHz. The experimental data-point distribution trajectory of the switching process shows a greater tendency to converge to the designed I–V curve compared with the single UI lookup table method.

High-Power High-Dynamic-Performance Space Solar Array Simulator Using Step-Wave Tracking Output Voltage Approach

With the power of high-orbit satellites now reaching dozens of kilowatts, solar energy sources play an important role in nonterrestrial applications. However, most of the existing high-power solar array simulators (SASs) are designed for simulating energy sources in terrestrial applications, and may not have suitable dynamic performance for nonterrestrial applications. This paper proposes a design for a high-power high-dynamic-performance space solar array simulator (SSAS) system, which combines a linear power stage unit and a multilevel bus tracking converter unit, in order to achieve a fast step-switching capability and high-power-handling capacity. In this paper, we consider the SSAS power system as two separate parts: the I–V power curve simulator that uses a linear power stage with 20 linear voltage-controlled current paths in parallel; and the multilevel bus tracking converter unit that provides the variable voltage levels tracking the SSAS output voltage, in order to decrease the power dissipation in the linear power stage. This paper establishes a mathematical model for the multilevel converter under this particular system architecture, and presents the application qualification conditions and system design principles. The proposed 2.4-kW SSAS can react quickly to a load step between the short-circuit and open-circuit states, which are the most challenging working conditions, at a stepping frequency of 3 kHz; this is a superior dynamic performance compared to other similar devices. The experimental results of testing the spacecraft power supply with a shunt regulator architecture demonstrating better performance, when compared to the results from four SAS modular products in parallel.

Development of Innovative Mechanical Flexible Solar Array Architecture

Flexible solar array architecture is proposed instead of rigid one, for high power solar array used from space tug mission to GEO satellite one, but also for specific scientific mission. THALES ALENIA SPACE has developed with Centre National d’Etudes Spatiales (CNES) support, innovative mechanical flexible solar array architecture, using 22 m long carbon tape-springs.The first part of the study was to design, predict, verify carbon tape-springs mechanical behaviour during deployment and coiling phases at room temperature. THALES ALENIA SPACE built mechanical flexible solar array mock-up full scale width / half scale length and performed deployment and rolling-up tests.The second part was to design, predict carbon tape-springs mechanical behaviour with large temperature range due to solar array missions. THALES ALENIA SPACE used again flexible solar array mock-up, performed deployment/coiling tests with innovative tape springs.This 11th ESPC paper describes results of these development activities and the THALES ALENIA SPACE forecast on this flexible solar array market.

A New European High Fidelity Solar Array Simulator for Near Earth and Deep Space Applications

Following an intensive design, development, and testing effort of almost 3 years, Rovsing with ESA assistance succeeded in the development of a new European high fidelity Solar Array Simulator (SAS) for near Earth and deep space applications. ESA now has a versatile, highly modular and efficient SAS at its disposition that serves at simulating modern high power solar arrays for Earth observation, science or telecom satellites as well as for future deep space missions.

Development of a New, High-Power Solar Array for Telecommunication Satellites

Airbus is currently developing the Next Generation Solar Array (NGSA) for telecommunication satellites. It is based on a hybrid array concept which combines a conventional rigid panel array with lightweight, semi-rigid lateral panels. The main figures of merit power/mass and power/volume can be doubled through this concept. Mechanically, the semi-rigid panels are the key new element. Through acoustic testing as well as sine vibration testing in air and in vacuum it was verified that these panels are suitable as cell support in stowed configuration. With the help of finite element modelling it is demonstrated that the semi-rigid panels are compatible with a free deployment. Electrically, the new array is to be equipped with a new generation of 4 junction solar cells with efficiencies above 30%. The increased radiation dose due to electric orbit raising has to be taken into account to arrive at the optimum shielding while still minimizing the array mass. By adjusting the ratio of rigid to semi-rigid panels and through the choice of solar cell type and mass, the NGSA can be tailored in a wide range to needs of a given platform. This is illustrated for the solar array to be flown on the new Airbus platform Eurostar Neo.

Stretched lens array squarerigger (SLASR): A unique high-power solar array for exploration missions

Over the past two years, development has begun on a unique high-power solar concentrator array called stretched lens array squarerigger (SLASR). SLASR marries the high electrical performance and low mass of the ENTECH stretched lens array (SLA) flexible blanket concentrator with the high structural performance and low mass of the ATK space squarerigger (SR) platform. SLASR offers unprecedented performance metrics for a space solar array of any type, including: • high power capacity (100 kW to multi-MW Class) • compact launch stowage (80–120 kW/m 3 ) • state of the art areal power density (300–400 W/m 2 ) • outstanding array-level specific power (300–1000 W/kg) • high-voltage operation at low insulation mass penalty (300–600 V) • excellent manufacturability using proven processes (cells and lenses at MWs/year) • improved radiation hardness at low shielding mass penalty (enabling solar electric propulsion space tugs through the radiation belts) • exceptional cost effectiveness (50–75 percent less than high-efficiency planar arrays) This paper describes SLASR technology, discusses SLASR developments to date, and outlines plans for SLASR technology maturation. The advantages of SLASR over other high-power solar array technologies are presented, including a comparison of key performance parameters for large-scale solar electric propulsion space tug missions.

Experimental study on high-voltage and high-power solar array secondary discharge

The secondary discharge is an important factor for power loss in the high-voltag e and high- power solar cell array. This paper studies the characteristics of th e secondary discharge and the breakdown mechanism through identifying the voltag e threshold where the secondary discharge will probably occur and monitoring the pulse current of the secondary discharge. The results show that increasing the operation voltage and string current will increase the possibility of the occurr ence of the secondary discharge on the solar array. The special structure design and the presence of RTV grouting between the solar cell strings can prevent th e secondary discharge incidents efficiently.

Spacecraft Technology for Broadcasting Satellites - An Update

This paper surveys the special technologies for presently conceived direct broadcast satellite (DBS) projects using high RF power in the band 12.2-12.7 GHz, allocated to the broadcasting-satellite service in the western hemisphere. The technologies include launch vehicles, shapedbeam antennas, traveling wave tubes (TWT's), electronic power conditioners (EPC's) for TWT's, lightweight high-power solar arrays, heat-pipe radiators, and output multiplexers. It is concluded that the technology is available, and only detailed engineering development and testing is required for construction.

Effects of Plasma Sheath on Solar Power Satellite Array

The structure of the plasma sheath and equilibrium voltage distribution of a high-power solar array governs various kinds of plasma-interaction phenomena and array losses. Sheath effects of a linearly-connected array are investigated for GEO. Although the array may be large, the thin-sheath-limit analysis may be invalid, necessitating numerical methods. Three-dimensional computer calculations show that potential barriers and over-lapping sheaths can occur, i.e., structures not predictable under the thin-sheath-limit analysis, but nevertheless controlling the distribution of plasma currents impacting on the array.