ABSTRACT:
A
variable frequency drive for an induction motor is proposed. The drive uses a
power factor (PF) correction bridgeless single-ended primary inductor
converter-controlled rectifier operating in discontinuous inductor current mode
as a front-end in order to improve the input power quality and a variation of
the constant volts per hertz controller, with feedback to regulate the velocity
of the motor shaft. The frequency slip is measured and compensated, since the
input stage. Experiments with and without load are carried out and presented.
Input power quality measurements are also presented. The proposed system is effective
to regulate the velocity and achieving a close to unity PF.
SOFTWARE: MATLAB/SIMULINK
Fig.
1 Proposed AC–DC–AC converter
Fig.
2 Results from experiments I and II
Fig.
3 Input voltage and current waveforms and input current harmonics
a
Input voltage and current waveforms, Channel 1 for current and Channel 2 for
voltage.
Current is measured by V–I converter with 1 V:1.6 A conversion ratio
b
First 39 non-fundamental current harmonics
CONCLUSION:
The
proposal of an SEPIC converter as the front-end of single-phase to three-phase
AC–DC–AC converter for an induction motor for improving the input power quality
is presented. It is also shown a variation of the CVH controller to regulate
the angular velocity of the motor shaft using the aforementioned topology. The
controller compensates the frequency slip, due to mechanical load, since the rectifying
stage. The experimental results show that the topology is effective for
regulating the velocity and that the topology can achieve a close to unity PF
and low THD. The computed spectrum can be used to design passive input filters
and further improve the THD and the PF of the circuit.
REFERENCES:
1
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2
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3
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4
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5
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bridgeless DCM SEPIC and Cuk PFC rectifiers with low conduction losses’, Trans.
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