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Damping resistance

Equivalent circuit

The equivalent circuit of a single switch consists of a controlled current source in parallel with a resistance, whose value shall be set by the user.

Behavior

If value is very high (closer to the blocking resistance ) the transition to the blocking state is more stable numerically, whereas if value is very small (closer to the conducting resistance ), the transition to conducting state is more stable. Therefore, the shall be placed between these extreme values. Besides, voltage error during transition is directly proportional to , while current error is inversely proportional to this value.

We suggest an approximation for value that yields lower steady-state errors:

where is the voltage across the switch just before it starts conducting and is the current through the switch just before it is blocked. It is worth mentioning that it is similar to Gen4 discrete-time switch conductance tuning expression.

Iterations

If and are not known before simulation starts, initial value of can be corrected if excessive errors are detected during simulation by iterations.

Relaxation

The relaxation parameters is related to the time it takes to reach steady state. This reduces the stiffness of the model, increasing its stability. However, a longer transition time also increases the error and losses in the model. Therefore, there is a balance between the accuracy of the model and its stability.