Monthly Archives: August 2022

TG Series for Starter-Generator Applications

There is a long-standing truism that good motors make good generators.  High efficiency, smooth operation, low harmonic distortion and weight optimization are commonly desired traits in both motors and generators. In the case of a starter-generator for applications like UAVs and ground-based portable systems, ThinGap motors can start an Internal Combustion Engine (ICE) with its high peak torque, then switch to generator mode to supply valuable conditioned power to onboard systems. What is effectively two functions from one electro-mechanical device.

An image of a UAV with a motor kit used as a starter-generator

ThinGap designs and builds high efficiency, air core-slotless motor kits with large through-holes and high-torque and power density. This architecture largely eliminates internal magnetic losses by virtue of design and offers the highest possible BLDC system efficiency (up to 95%).  The low impedance Stator provides a stable, pure 3-phase sinusoidal, low-droop (less than 1% harmonic distortion) voltage output. Because of the thin radial cross section and with an optimized Rotor, the bulk of the material is at the maximum radius yielding high torque.

As part of its ongoing support of Government end-customers, ThinGap and its industry partners were recently selected for two different airborne starter-generator projects for use on DOD platforms. ThinGap has been supplying starter-generators for several years, and recently has worked to expand offerings and more widely deploy these solutions. There is growing demand, especially in Defense, for generators that run off a heavy full engine.

To better understand ThinGap’s position in supplying electric motors for starter-generators, it helps to understand starter-generators. Starter-generators are a unique application that requires high peak starting torque at relatively low speed, and then power generation at high speed. Aircraft require starter-generators to begin operation, where on startup in both piston and jet turbine powered aircraft, power is drawn from onboard batteries to operate the starter-generator first as a motor to get the main engine up to a speed that can sustain combustion for propulsion. This process takes a few seconds on piston motors and up to a minute with jet turbines. Once combustion has been sustained, current is cut to the starter, and from there the free-spinning rotor is driven by the crankshaft or turbine shaft to now act as a generator to power aircraft systems and recharge the aircrafts internal power supply from startup.

ThinGap’s TG Series is ideal for starter-generator applications. This is enabled by the lightweight wave-wound composite Stator, and weight-optimized Rotors with large clear internal apertures which can be integrated into both piston and turbine engines. For the TG Series, peak torque capacity is much higher, giving a dynamic response significantly better than the competition at a lighter weight.

The TG Series is air cooled by convection, and unlike most motor kits generates more power the faster it is spinning, due to faster airflow over the composite coil, and power ranges between 3-7 kW when used as a starter-generator, and standard offerings range between 5 and 7 inches in diameter, with custom motors delivered for UAV applications as large as 14 inches.

To learn more about ThinGap’s TG Series of motor kits, click here.