The utilisation of advanced electrical machines in the automotive industry is growing very rapidly, driven by the demands for improved fuel efficiency, emissions reduction and performance benefits.  Many of these new applications place exceptionally demanding design challenges on the electrical drive system, requiring very high performance at low cost whilst operating in difficult mechanical and thermal environments, often at low voltages. 

These requirements are “pushing the boundaries” of existing motor and control technology but SR Drive® technology has risen to this challenge.  With a unique blend of performance attributes - high efficiency, robustness, reliability, high temperature capability and operation over wide speed range - SR Drive® technology is being developed by NSRD for many applications including: starter generators, hybrid traction drives, actuators and turbo machinery.




SR Drives® : Benefits in the Automotive industry.

Highly efficient over a wide speed range

  • Minimal rotor losses due to the absence of any rotor windings or conductors.
  • Low switching frequencies minimize electrical losses in the power converter.

A very compact solution

  • Stator coils have exceptionally short end-windings, allowing high torque capability from a very small motor.
  • Low switching frequencies reduce the size and rating of the power electronics.

Highly cost effective solutions

  • Straight-forward motor construction requires minimal tooling investment.
  • Reduced power electronics ratings permit cost savings over conventional solutions.

Fundamentally robust and reliable

  • Absence of rotor windings reduces bearing temperatures and extends bearing/lubrication lifetimes.
  • No permanent magnets, so no risk of torque loss due to de-magnetization or of uncontrolled generating modes at high-speed.
  • Precise speed control is possible without external sensors.

Fault tolerant

  • System operates even with one phase down – vital ‘limp home’ capability.
  • Unlike conventional drives, there is no short circuit path in the drive output stage.


  • Simple construction is based on re-cyclable core materials: iron and copper

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