A typical ICE turbo may spin at 200,000 rpm or faster, while Garrett’s biggest fuel-cell compressors top out at about 150,000 revs. While lower than ICE, that’s high for an e-compressor, and such speeds help shrink the package size. One complication of the fuel-cell compressor is that its electric motor, a synchronous permanent-magnet type, must spin at the same speed—there’s no reduction geartrain involved. That’s about 10 times faster than a traction motor spins, and it’s too fast for traditional sensors to measure turbine speed and position. Instead, Garrett’s sophisticated software algorithms infer this data ten times per revolution based on voltage and current.
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