Crimson Racing Wiki

Emrax 228

Subteam: EV Power SystemsSubsystem: Tractive SystemAssembly: Drivetrain AssemblyCars: CR26E

Purpose

Convert electrical energy from the accumulator into torque at the differential.

Function

A liquid-cooled axial-flux permanent magnet synchronous motor with a custom winding. EMRAX is effectively the only viable option for an FSAE car not running in-hub motors.

Design Process

The 228 LV+43% winding maintains the same 111 kW peak power and performance as the 228 MV at a lower maximum operating voltage, which is what allowed it to match the pack. The custom winding was agreed with the manufacturer after exchanging pack specifications. From the design reports and one-pagers: The motor decision was based on continuous simulation in OptimumLap against torque curves provided by EMRAX. DTI provides both the custom winding and a matching inverter, and the two were bought together as the zapDrive-x 400-110 kit.

Design Constraints

T.5.3.1 requires the rotating part of the motor be contained in a structural casing, minimum 3.0 mm for 6061-T6 aluminium or 2.0 mm for steel. T.5.3.2 requires a scatter shield if the casing rotates around the stator or is perforated. Lead time is roughly 6 months, which is why it was ordered alongside the cells.

Analysis

Validation: run the HV system on the test bench across different scenarios to develop torque and power curves and confirm the reliability of the motor and controller together.

Full Material List

Purchased unit. Liquid cooled, IP65 (competition recommendation is IP65), maximum temperature 120 C, 12.4 kg (27.3 lb), customisable sprocket mount and chassis motor mount.

Reoccuring issues

None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.

Properties

Up to 98% efficiency. Peak power 111 kW as wound. From the cost report drawings and CAD: Weighed mass: 13502.3 g (29.767 lb). Source: Subteam weight books: CR26E/EV Power Systems/Car/Design/_General/Documentation/Old files/EV Component Weights - Fall 2025.xlsx Quantity per car, as costed: 1

Still to document

Nothing in CrimsonStorage covers these yet.