MPC-model predictive control. here we uses mpc controller,for current control in 3-phase inverter... converter model, load model, cost function.

2.  ABSTRACT
 INTRODUCTION
 MPC-MODEL PREDICTIVE CONTROL
 ILLUSTRATTION OF MODEL PREDICTIVE CONTROL
 MPC-CONTROLLER
 PREDICTIVE CURRENT CONTROL
 PREDICTIVE CURRENT CONTROLALGORIITHM
 ADVANTAGES PREDICTIVE CURRENT CONTROL
 COST FUNCTION
 CONVERTER MODEL
 LOAD MODEL
 CONCLUSION

3. A new predictive strategy for current control of a three-phase inverter is
presented. The algorithm is based on a model of the system. From that
model, the behaviour of the system is predicted for each possible switching
state of the inverter. The state that minimizes a given quality function g is
selected to be applied during the next sampling interval. Several
compositions of g are proposed ,including terms dedicated to achieve
reference tracking, balance in the dc link, and reduction of the switching
frequency . In comparison to an established control method, the strategy
presents a remarkable performance..

4. Current control is one of the most studied problems in power
electronics , so it is very important to study the application of
MPC in a current control scheme. In addition, the three-phase,
two-level inverter is a very well-known topology that can be
found in most drive applications.

5.  MPC HAS RESPONSIBILITY TO COMPUTE THE
PLANTS INPUT TO PREDICT THE FUTURE.
 MPC IS A FEEDBACK CONTROLLER ALGORITHM.
 MPC USES MODEL TO MAKE PREDICTIONS ABOUT
FUTURE OUTPUTS OF A PROCESS.
 MPC CAN HANDLE MULTI INPUT AND MULTI
OUTPUT (MIMO) SYSTEM.
 MPC CAN HANDLE CONTRAINTS.
 MPC HAS PREVIEW CAPABILITY(FEED FORWARD
CONTROL).

7.  MPC CONTROLLER USES MODELOF THE PLANT AND
OPTIMIZER
 MODEL OF THE PLANT -TO MAKE PREDICTIONS
ABOUT THE FUTURE PLANT OUTPUT BEHAVIOUR.
 OPTIMIZER -WHICH ENSURES THAT THE PREDICTED
FUTURE PLANT OUTPUT TRACKS THE DESIRED
REFERENCE.
 OPTIMIZER REDUCES THE ERROR BETWEEN THE
REFERENCE AND THE PREDICTED VALUES.

8.  Straightforward formulation, based on well understood
concepts
 Explicitly handles constraints •
 Explicit use of a model
 Well understood tuning parameters –Prediction horizon –
Optimization problem setup
 Development time much shorter than for competing advanced
control methods
 Easier to maintain: changing model or specs does not require
complete redesign, sometimes can be done on the fly

10. The proposed predictive control strategy is based on the fact
that only a finite number of possible switching states can be
generated by a static power converter and that models of the
system can be used to predict the behaviour of the variables
for each switching state.

11.  The value of the reference current i∗(k) is obtained from an
outer control loop, and the load current i(k) is measured.
 The model of the system is used to predict the value of the
load current in the next sampling interval i(k+1) for each of the
different voltage vectors.
 The cost function g evaluates the error between the reference
and predicted currents in the next sampling interval for each
voltage vector.
 The voltage that minimizes the current error is selected and
the corresponding switching state signals are generated.

12.  Define a cost function g.
 Build a model of the converter and its possible switching
states.
 Build a model of the load for prediction.

13.  The objective of the current control scheme is to minimize the
error between the measured currents and the reference values.
 This requirement can be written in the form of a cost function.
 The cost function is expressed in orthogonal coordinates and
measures the error between the references and the predicted
currents:
g =| i∗ α(k+1)−ip α(k+1)|+| i∗ β(k+1)−ip β(k+1)|
where ip α(k+1) and ip β(k+1) are the real and imaginary parts of
the predicted load current vector ip(k+1),. The reference
currents i∗ α(k+1) and i∗ β(k+1) are the real and imaginary parts of
the reference current vector i∗(k+1).

14. The power circuit of the three-phase inverter converts
electrical power from DC to AC form using the electrical
scheme shown in Figure. Considering that the two switches in
each inverter phase operate in a complementary mode in
order to avoid short-circuiting..

17. Taking into account the definitions of variables from the
voltage source inverter circuit, the equations for load current
dynamics for each phase can be written as

19. The predictive current control presented in this Letter does
not require any current controller or modulator. It presents a
very effective control of the load currents. In addition, this
control strategy compares well with established control
methods such as sub harmonic modulation (PWM). The
dynamic response of this method is better than the classical
PWM solution.