equips the starting current command I,, that decreases
with the time. After the first current wave, the starting current
command value is compared with the commutation
command value, and the commutation reference uses a large
value between two commands.
4 Experimental results
The composition of experiment system is shown in the
Fig. 9. This system is composed of the initial rotor position
estimation circuit using the proposed estimation method
and sensorless drive circuit that are explained with the
section 2 and the section3. In the starting mode, switching
of the inverter is started to the suitable timing based on the
initial rotor position estimation results. Therefore, the
smooth starting without reverse rotation is performed.
The saturable yoke is present with the proposed PM
motor for the rotor position estimation at stand-still mode.
Consequently, the leakage flux increases when the proposed
PM motor is compared with a normal opened slot stator
core motor, so that it may think that the performance of the
proposed PM motor slightly goes down. Therefore, the
examinations of the various characteristics of the proposed
PM motor are required.
We investigated the motor efficiency of the proposed
PM motor driven in the steady state. And the motor
efficiency is calculated from the input and the output of the
PM motor.
Fig. 10 shows relation between the torque and the
armature current at 4100 rpm that is rated motor speed. The
torque and the armature current are proportionate relation,
and there is no effect of the saturable yoke.
Fig. 11 shows relation between the motor efficiency and
the power factor against the output at 4100 rpm. The motor
efficiency rises as the output becomes large. The motor
efficiency finally reached 60.7 percent at the torque of
equips the starting current command I,, that decreaseswith the time. After the first current wave, the starting currentcommand value is compared with the commutationcommand value, and the commutation reference uses a largevalue between two commands.4 Experimental resultsThe composition of experiment system is shown in theFig. 9. This system is composed of the initial rotor positionestimation circuit using the proposed estimation methodand sensorless drive circuit that are explained with thesection 2 and the section3. In the starting mode, switchingof the inverter is started to the suitable timing based on theinitial rotor position estimation results. Therefore, thesmooth starting without reverse rotation is performed.The saturable yoke is present with the proposed PMmotor for the rotor position estimation at stand-still mode.Consequently, the leakage flux increases when the proposedPM motor is compared with a normal opened slot statorcore motor, so that it may think that the performance of theproposed PM motor slightly goes down. Therefore, theexaminations of the various characteristics of the proposedPM motor are required.We investigated the motor efficiency of the proposedPM motor driven in the steady state. And the motorefficiency is calculated from the input and the output of thePM motor.Fig. 10 shows relation between the torque and thearmature current at 4100 rpm that is rated motor speed. Thetorque and the armature current are proportionate relation,and there is no effect of the saturable yoke.Fig. 11 shows relation between the motor efficiency andthe power factor against the output at 4100 rpm. The motorefficiency rises as the output becomes large. The motorefficiency finally reached 60.7 percent at the torque of
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