Photovoltaically powered satellites serve a wide variety of applications in Earth orbit and beyond. Use cases extend from direct-to-phone communications with satellites in low Earth orbits to astronomical observation with satellites in solar orbits. But before a satellite can leave Earth, it must undergo extensive ground tests.
Satellite Power System Validation
In particular, the satellite’s power system must demonstrate that it can extract sufficient energy from the solar array that the satellite will deploy at its ultimate destination. In addition, the power system must also show that it can condition and regulate this power to safely apply the correct voltages to the satellite’s sensitive payloads and store energy for use when the array is not fully illuminated. Power-system tests require a solar-array simulator (SAS) that can mimic on demand the different outputs that an actual array will deliver as the satellite experiences eclipse events and other conditions that can inhibit illumination intensity.
Case Studies on Successful Satellite Testing with Solar-Array Simulator
AMETEK Programmable Power has nearly three decades of experience building solar-array simulators for satellite power testing. The company’s systems have found use in the testing of spacecraft, including the James Webb Space Telescope (JWST), as described in our recent application note, Solar Array Simulator Helps Get Satellites into Orbit. The JWST is located at Lagrange point 2, 1.5 million kilometers from Earth opposite the sun, successfully relaying spectacular images of the universe. Northrop Grumman, the prime contractor on the JWST, employed an AMETEK Programmable Power Elgar Solar Array Simulator (SAS) during ground tests of satellite power simulation.
The space-grade SAS used in the JWST tests consisted of units that delivered 1,000 W each in a 3U standard rack height. AMETEK Programmable Power has now introduced a new simulator—the Elgar Advanced Solar Power Simulator (ASPS)—that offers 1,200 W in a 1U chassis. You can choose either a version with a single 1,200-W channel or one with two independent 600-W channels. In addition, the modern design of the Elgar ASPS enables the company to offer a price reduction of about 30% compared with the earlier Elgar SAS.
Solar-Array Simulator Protection Features
An ASPS system has all the satellite power system safety features necessary to handle the many solar-array simulation tasks required for thorough satellite power testing, as outlined in our recent white paper Ground Tests of Photovoltaically Powered Satellites Require Fast and Flexible Solar Array Simulation. For example, the ASPS offers considerable flexibility to handle the predominant methods of power transfer from an array to a satellite’s power conditioning and distribution unit (PCDU), including direct energy transfer (DET) with sequential switching shunt regulation (S3R) and maximum power point tracking (MPPT).
For DET, the ASPS offers a fast 2-µs response time that approaches an actual solar array's nearly instantaneous response time, enabling the effective test of power-conditioning and distribution units (PCDUs) that employ shunt regulation. For PCDUs that use MPPT, the ASPS’s current-regulator output can simulate the soft I-V curves of various solar arrays while supporting a 200-Hz tracking speed. The ASPS incorporates a switching power supply to provide bulk power efficiently, but it adds linear FETs to create a responsive, realistic I-V curve. In addition, the ASPS supports an effectively infinite number of eclipse event profiles.
Satellite Power System Communications and Safety
The ASPS incorporates a standard LAN interface for communications and remote control and operates with standard SCPI commands and AMETEK SAS software. These satellite power system safety features simplify system-level integration and make it easy for a third-party integrator to configure a complete solar array simulator at a customer’s facility. An intuitive, easy-to-use front-panel color touch panel display facilitates setup and the monitoring of ongoing operations, providing voltage and current readback as well as the state of output relays—displaying gray for an idle state, green for a conductive state, blue for a shunted state, and red for a fault state.
Finally, the ASPS includes a variety of solar-array simulator protection features to protect the delicate components within the expensive satellites under test as well as the test personnel. These safety features include:
- Overvoltage and overcurrent protection on the ASPS output and its input bulk power supply.
- Fast (10 µs) electronic circuit breaker to add another layer of protection when overvoltage or overcurrent events occur.
- Monitoring of the bus voltage levels within the satellite itself and shut down should a satellite overvoltage condition occur.
- Overtemperature protection, which shuts the system down if it overheats.
- A fault data recorder continuously monitors voltage and current and streams the data back to a host computer at a rate of 100 times per second for analysis and storage.
The ASPS complements AMETEK Programmable Power’s full line of AC and DC programmable products, including battery string simulators with application-to-space applications. In addition to providing ASPS models for system integration at your facility, AMETEK Programmable Power’s sales and support staff have test engineering experience to configure a complete ASPS-based next-generation solar-array simulator for you. For more information, take a look at our white paper, Ensure Reliable Satellite Performance with Advanced Solar Array Simulation, or visit www.ProgrammablePower.com.
