Z-Force Motor/IPM Update

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In 2016, Zero introduced an interior permanent magnet (IPM) design as distinguished from a surface permanent magnet (SPM) design of the original motor introduced in 2013.

  • An IPM design places the rotor magnets in physical slots within its circumference, instead of binding the magnets to the rotor's circumference via special epoxies.
  • The IPM design reduces the heating associated with developing magnetic flux and distributes the heat produced more evenly.
    This allows the motor to operate at higher outputs while producing less heat overall and concentrating heat production where it dissipates more easily.
    In practice, this avoids hitting thermal limits which require cutbacks to protect the motor windings.
Controller Programming Note
  • The IPM design motor apparently involves custom Zero programming of the Sevcon controller for the encoder, so off the shelf DVT software cannot perform alignment/commissioning but can apply settings / DCF files and restore them.
Production / Rollout
  • 2016 models S/DS/SR/DSR/FXS have the IPM design.
  • FX and S/DS models with a 3-brick battery retained the SPM design (presumably to be phased out with inventory).
  • As of 2017, statements from Zero indicate that once the IPM motor design was in production, SPM motor production ceased, and all replacements of SPM motors would use IPM motors.
References
Zero livestream announcing 2016 upgrades
Zero livestream presentation with Ryan Biffard about the Z-Force motor IPM upgrade