Simplified SVPWM Algorithm for
Neutral Point Clamped 3-level Inverter fed DTC-IM Drive
ABSTRACT:
In this paper, a simplified space vector pulse width
modulation (SVPWM) method has been developed for three phase three-level
voltage source inverter fed to direct torque controlled (DTC) induction motor
drive. The space vector diagram of three-level inverter is simplified into
two-level inverter. So the selection of switching sequences is done as conventional
two-level SVPWM method.Where in conventional direct torque control (CDTC), the
stator flux and torque are directly controlled by the selection of optimal
switching modes. The selection is made to restrict the flux and torque errors
in corresponding hysteresis bands. In spite of its fast torque response, it has
more flux, torque and current ripples in steady state. To overcome the ripples
in steady state, a space vector based pulse width modulation (SVPWM)
methodology is proposed in this paper. The proposed SVPWM method reduces the
computational burden and reduces the total harmonic distortion compared with
2-level one and the conventional one also. To strengthen the voice simulation
is carried out and the corresponding results are presented.
KEYWORDS:
1.
SVPWM
2.
DTC
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.1.Block
diagram of proposed DTC drive.
CONCLUSION:
In
this paper, a simplified SVPWM algorithm is presented for three-phase
three-level inverter fed DTC drive. The proposed algorithm generates the
switching pulses similar to a two-level inverter based SVPWM algorithm. Thus,
the proposed algorithm reduces the complexity involved in the existing PWM
algorithms. To validate the proposed PWM algorithm, numerical simulation
studies have been carried out and results are presented. From the simulation
results, it can be concluded that the three-level inverter fed DTC drive gives reduced
steady state ripples and harmonic distortion.
REFERENCES:
[1] F. Blaschke “The principle of field
orientation as applied to the new transvector closed loop control system for
rotating-field machines," Siemens Review, 1972, pp 217-220.
[2]
Isao Takahashi and Toshihiko Noguchi, “A new quick-response and high-efficiency
control strategy of an induction motor,” IEEE Trans. Ind. Applicat.,
vol. IA-22, no.5, Sep/Oct 1986, pp. 820-827.
[3]
Domenico Casadei, Francesco Profumo, Giovanni Serra, and
Angelo Tani, “FOC and DTC: Two Viable Schemes for Induction Motors Torque
Control” IEEE Trans. Power Electron., vol. 17, no.5, Sep, 2002, pp.
779-787.
[4]
D. Casadei, G. Serra and A. Tani, “Implementation of a direct torque control
algorithm for induction motors based on discrete space vector modulation” IEEE
Trans. Power Electron., vol.15, no.4, Jul 2000, pp.769-777.
[5]
Nabae, A., Takahashi, I., and Akagi, H, "A neutral-point clamped PWM inverter’,
IEEE-Trans. Ind. Appl., 1981, 17, (5), pp.518-523.
