Predictive Control of Power Converters and Electrical Drives

12.3 Delay Compensation Method

A simple solution to compensate this delay is to take into account the calculation time and apply the selected switching state after the next sampling instant. In this way, the control algorithm is modified as follows:

1. Measurement of the load currents.

2. Application of the switching state (calculated in the previous interval).

3. Estimation of the value of the currents at time t_k+1, considering the applied switching state.

4. Prediction of the load currents for the next sampling instant t_k+2 for all possible switching states.

5. Evaluation of the cost function for each prediction.

6. Selection of the switching state that minimizes the cost function.

The predictive control algorithm with delay compensation can also be represented as the flowchart presented in Figure 12.5. Compared to the original control algorithm shown in Figure 12.2, application of the new voltage vector is moved to the beginning, and the estimation of the currents at time t_k+1 is added. Note that the estimation of the currents increases the calculation time, but only marginally because it must be calculated only once.

Figure 12.5 Flowchart of the predictive current control with delay compensation

The operation of the predictive control with compensation delay is shown in Figure 12.6. Here, the measured currents and the applied switching state at time t_k are used in ...