Hi Phan,
As you can clearly see in the error message that when you simulate the model an algebric loop is detected and hence an error is thrown.
An algebraic loop occurs when a signal loop in a model contains only blocks that have direct feedthrough. Direct feedthrough refers to blocks that use the input value for the current time step to calculate the output value for the current time step. A signal loop that contains only blocks with direct feedthrough creates a circular dependency of block output and input values in the same time step. The resulting equation is an algebraic equation that requires a solution at each time step and adds computational cost.
One method to solve the algebric loops is you can add the delay blocks in the loop, hence the input and output time stamps will be different and the simulink will have a starting point to begin the calculation.
Below is the MathWorks documentation that you can refer for more information:
Hope it helps.
