Z-Force Motor/IPM Update
From Unofficial Zero Manual
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.