C. Phase inductance
The phase inductance was determined from the phase winding
linkage flux. The magnetic flux linkage Ψ was obtained by
an integration, from time t0 until t1, of the winding induced
voltage (u(t) − Rf i(t)) during a step response of the phase
current to the step change of the winding input voltage in time
t0.
Ψ = t1
t0
u(t) − Rf i(t)dt (2)
Li = Ψ
i (3)
These measurements were done for different positions and
so the inductance of the phase as a function of the rotor
position was determined (see Fig. 7). The inductance of the
motor rises from around 1mH at an unaligned position to over
7mH at an aligned position. It can be seen that the calculated
and the measured values have close correlation.
D. Efficiency map of the motor
The efficiency distribution for various speeds and torques is
shown in Fig. 8. It is defined for whole working range of the
optimized SRM. Efficiency calculation approach is detailed
described in [9]. As it can be seen from this figure, the
maximal efficiency is around 92% for rated speed 5000 rpm
and rated load.
Fig. 7. The phase inductance as the function of rotor position for 20 A.
Fig. 8. The efficiency map of the optimized SRM.
VI. CONCLUSION
Newly proposed algorithm described in [9] was used to
optimize SRM as the replacment of the DC motor in first
Slovak electric car. The optimized motor was built and experimentally
verified. The experimental results closely follow
the calculated results. The theoretical and experimental results
demonstrate the high accuracy and suitability of the approach
for design optimization of the SRM. This unique approach can
also be used to optimize other types of the motors, when parts
specifically related to switched reluctance motor are adjusted
accordingly.