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World First Certification
Ever wondered what it takes to test a new electric motor design powerful enough to fly a plane? In this blog post, we’ll take you behind the scenes of ZeroAvia’s Back-to-Back Electric Motor Test Rig, outline how the rig supports the development our high-power Electric Motor and ultimately, how this will bring ZeroAvia closer to certifying the 600kW Electric Propulsion System for aviation.
The rig has been built to test our prototype electric motors, along with our certification units that form part of the 600kW Electric Propulsion System (EPS) and also the company’s ZA600 hydrogen-electric powertrain. The set up involves coupling our motor to a secondary motor to effectively simulate a dynamic load i.e., the propellor. The work has been a developmental project for the System Test team, allowing ZeroAvia to trial certification test processes and procedures for both rig development and test campaign delivery, in readiness for the now started EPS testing on our dyno in Seattle and, ultimately, the full ZA600 hydrogen-electric test programme.
The rig operates as a regeneration dynamometer, enabling power regeneration through the secondary electric motor, creating a closed circuit and efficient testing up to 600kW max power using only 170kW of input power. The cooling system can take up to 160kW and up to 15 power channels can be measured at any one time. This allows several variables to be measured, including current, voltage, speed and torque.
ZeroAvia’s current test campaign involves many stages of testing, beginning from slow-speed and high-speed tests that measure the torque ripple. This involves measuring the fluctuations in torque output of the motor, which will help to ensure that the motor is designed for reduced noise and vibration during operation. Electrical testing will measure the performance and reliability of the motor and isolation testing can examine the integrity of the motor’s insulation between the windings and the frame – the insulation health is checked by running a high voltage through the motor and measuring the leakage current.
It is especially important to characterise the motor in different scenarios, meaning tests are carried out at different speeds, beginning at 500 RPM up to 2,000 RPM; the motor is also tested at higher powers and for varying durations at different temperature profiles. In this way, we are expanding the envelope of our motor, such that we can validate our design for operation within an aircraft, where the motor will experience a variety of characteristics and environmental aspects. The rig can also be used to test ZeroAvia’s certification units with the company’s 200kW Silicon Carbide Inverters, which together make up the 600kW EPS.
The System Test Team works closely with a number of teams across the company, such as the design team, which is fed back essential data in order to validate their models. They are also coordinating with the Safety and Certification Team, to collect and transfer data to the regulators. ZeroAvia’s UK System Test Team also works closely with the US Electrical Propulsion System Team in the US, that are carrying out testing of the ZeroAvia 600kW electric motor on their dynamometer in the company’s Propulsion Centre of Excellence. Data from both rigs can then be correlated to support the certification program of the 600kW Electrical Propulsion System with the FAA, in the US.
ZeroAvia plans to type certify its 600kW Electric Propulsion System with the US regulator before certifying its full 600kW hydrogen-electric powertrain (ZA600), of which the EPS is a core system. The company has already received consensus on the Certification Basis with the FAA, having received the G1 issue paper in February this year. The company is now continuing to build a portfolio of testing data to validate its design using the Back-to-Back Motor Rig in the UK and the 600kW Motor Dynamometer in the US, before carrying out testing of the full 600kW Powertrain (including the Hydrogen Fuel Cell Power Generation System) at its Full Engine Test Facility at Cotswold Airport, UK.
