Variable Flux Reluctance Motor: Developing a variable flux motor with wide power band characteristics

DATE

January 4, 2021

A variable flux motor using a single set of coils. This motor is driven by AC-DC superimposed currents.

Key Word : Motor, hybrid electric vehicles

Background / Context / Abstract:

Traction motors for EVs (Electric Vehicles) and HEVs (Hybrid Electric Vehicles) require wide power band characteristics. In order to increase the power band, field weakening control is widely used in IPM motors. However, the effectiveness of the field weakening control is not sufficient for use in traction motors for vehicles. In order to increase the power band, a variety of variable flux motors have been proposed. However, they are not practical due to  the requirement of 2 separate sets of coils: armature coils and field coils.

Technology Overview:

In order to solve these problems, researchers at Osaka University proposed a variable flux motor using a single set of coils. This motor is driven by AC-DC superimposed currents. DC voltages (+V, −V) and AC voltages (Vu, Vv, Vw) are superimposed, and 6 voltages (Vu+V, Vv+V, Vw+v, Vu−V, Vv−V, Vw−V) are applied to the motor using a 6-phase inverter. However, conventional control techniques for 3-phase motors are applied to this motor because 6 phases consist of 2 sets of 3 phases. This motor achieved wide power band characteristics with a simple constitution.

Benefits:

・Superimpose DC and AC currents using a 6-phase inverter
・Wide power band and high efficiency due to its variable flux characteristics

Further Details:

The power band of this variable flux motor is more than 2 and 4 times as wide as that of induction motors and IPM motors, respectively.
This AC-DC superimposition technique can be applied to permanent magnet motors.

Potential Applications / Potential Markets:

・Electric vehicle
・Construction machine
・Electric train
・Windmill

State of Development / Opportunity / Seeking:

・Available for exclusive and non-exclusive licensing
・Exclusive/non-exclusive evaluation for defined period (set up for options)
・Collaborative/supportive research

IP Status:

WO 2015/186714 (National phase EP, US)

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