NASA has effectively installed Calnetix Technologies’ Four Bed Carbon Dioxide Scrubber (FBCO2) high-speed ventilation system on the International Space Station (ISS), as reported by Calnetix Technologies. In an exclusive interview with Power Electronics News, Matthew Farides, Director of Business Development, Calnetix Technologies, highlighted how the deployment of Calnetix’s first magnetic bearing blower in space is a significant milestone.
Calnetix’s active magnetic bearing (AMB) system used in the 4BCO2 blower is a 5-axis system which provides frictionless operation and no primary wear components. “It is not significantly affected by gravity. Whether on the ground, or at zero gravity in orbit, the AMB actuators provide ample margin (more than 300% of expected aerodynamic load) to levitate and maintain the position of the rotor and impeller wheel,” said Farides.
AMBs from Calnetix are equipped with position sensors, electro-magnetic actuators, and a microcontroller, making machine health monitoring and diagnostics readily available. Advanced diagnostics enable the identification, analysis, and archiving of the machine’s health and historical performance when connected to an external computer.
He added, “the actual installation process was relatively straightforward and mercifully unremarkable due to the proactive approach and de-risking work, which was performed before the blower system was launched. On the flip side, the installation process in orbit took longer than anticipated just due to the nature of performing the physical operations in a tight space vs. a factory floor.”
In the past, the carbon dioxide removal assembly (CDRA) system on the ISS relied upon a foil air-bearing supported blower, which requires pneumatic pressure and high operating speeds for lubrication. NASA was seeking to procure a technology that must operate at the extreme end of the performance envelope in order to meet the future CO2 removal requirements.
“Other air circulation systems built on conventional bearings have a shorter life span, are usually susceptible to contamination, can be prone to wear with many starts and stops or with improperly filtered air, and usually require maintenance to meet the lifetime requirements of the system,” said Farides.
As a replacement for the legacy blower, Calnetix suggested installing a Magnaforce high-speed permanent magnet motor on Powerflux active magnetic bearings (AMBs) in an integrated casing.
“Calnetix’s blower system includes a compact Momentum In-line Blower on magnetic bearings and an integrated Continuum Dual Controller to drive the blower. The in-line blower consists of a centrally located five-axis AMB system, backup bearings, a permanent magnet motor and an overhung centrifugal impeller in a very compact package,” said Farides.
Calnetix’s system
Farides explained that the Four-Bed Carbon Dioxide Scrubber (FBCO2) system is the latest current configuration and has been operating on the station since 2021. “The FBCO2 is a next-generation Environmental Control and Life Support System set to be tested on the space station for one year, helping recycle and regenerate most of the air and water necessary to sustain its crew. It uses commercial adsorbent materials to retain water vapor while filtering carbon dioxide out of the space station’s airflow, allowing for an environmentally safe crew cabin,” said Farides.
Calnetix’s magnetically levitated in-line blower is designed to propel the ventilation through the FBCO2 system in a microgravity space environment. The compressor forces air from the International Space Station (ISS) through a CO2 sorbent bed and a desorbing desiccant bed.
Due to their frictionless functioning, magnetic bearings were utilized in place of conventional bearings to dramatically improve the system’s performance, dependability, and durability. According to Farides, AMBs can operate in a near-vacuum if they are designed for it because they can withstand pressure changes more easily and reliably at lower pressures. The historical air bearing solution is less tolerant of particle pollution than the Calnetix blower system with AMB, which is designed to function at extremely high speeds.
The magnetic bearing blower system from Calnetix may be added to future environmental control system applications envisioned by NASA, such as outposts in space, on the Moon, and even on Mars. “Our magnetic bearing systems may now be used in upcoming space and aerospace applications, such as fluid pumps, reaction wheels, and gyroscopes that challenge traditional bearing technologies, thanks to the successful deployment and functioning of the magnetic bearing blower on the ISS,” said Farides.
Motor Technology
Calnetix in-line blower system utilizes Magnaforce high-speed permanent magnet motor on Powerflux active magnetic bearings (AMBs). Due to frictionless functioning, AMBs boost FBCO2 system dependability, longevity, and performance. They tolerate particle impurities and may be actively regulated using software-changeable bearing qualities after installation and commissioning. This may modify blower operating conditions without hardware changes.
The Continuum Dual Controller is an integrated controller developed for driving or controlling a permanent magnet motor on magnetic bearings for specialized applications. “The dual controller consists of a Vericycle Variable Speed Drive (VSD) for the motor and an AMB controller in a single compact package that supports speeds up to 60,000 RPM. The VSD provides speed and torque control to the PMSM section, and the AMB Controller section operates the five axis of control in the AMB’s,” said Farides. According to the company, the primary advantage of integrating these control systems into one unit is a more densely packaged solution with a simplified interface to the (space) vehicle.
Due to the rotor’s capability of magnetically coupling to the stator with minimal flux fringing in the axial and transverse directions, the magnetizing efficiency is high and the back EMF per magnet volume is high. Due to surface mounting techniques that isolate circulating electrical paths without compromising electromagnetic or structural integrity, rotor harmonic currents are minimal. Minimal rotor air gap and air gap cooling requirements as a result of the high-strength composite sleeve’s near-zero harmonic eddy current losses.
The new scrubber blasted off to the ISS in November 2022 after extensive ground testing at NASA Marshall in Huntsville, Alabama facility.
