Implement diode model
Fundamental Blocks/Power Electronics
The diode is a semiconductor device that is controlled by its own voltage Vak and current Iak. When a diode is forward biased (Vak > 0), it starts to conduct with a small forward voltage Vf across it. It turns off when the current flow into the device becomes 0. When the diode is reverse biased (Vak < 0), it stays in the off state.
The Diode block is simulated by a resistor, an inductor, and a DC voltage source connected in series with a switch. The switch operation is controlled by the voltage Vak and the current Iak.
The diode internal resistance Ron, in ohms (Ω). The Resistance Ron parameter cannot be set to
the Inductance Lon parameter is set
The diode internal inductance Lon, in henries (H). The Inductance Lon parameter cannot be set to
the Resistance Ron parameter is set
The forward voltage of the diode device, in volts (V).
Specifies an initial current flowing in the diode device. It is usually set to 0 in order to start the simulation with the diode device blocked. If the Initial Current IC parameter is set to a value greater than 0, the steady-state calculation considers the initial status of the diode as closed.
Initializing all states of a power electronic converter is a complex task. Therefore, this option is useful only with simple circuits.
The snubber resistance, in ohms (Ω). Set the Snubber resistance Rs parameter to
eliminate the snubber from the model.
The snubber capacitance in farads (F). Set the Snubber capacitance Cs parameter to
eliminate the snubber, or to
inf to get a resistive
If selected, adds a Simulink® output to the block returning the diode current and voltage.
The Simulink output of the block is a vector containing two signals. You can demultiplex these signals by using the Bus Selector block provided in the Simulink library.
The Diode block implements a macro model of a diode device. It does not take into account either the geometry of the device or the complex physical processes underlying the state change . The leakage current in the blocking state and the reverse-recovery (negative) current are not considered. In most circuits, the reverse current does not affect converter or other device characteristics.
Depending on the value of the inductance Lon, the diode is modeled either as a current source (Lon > 0) or as a variable topology circuit (Lon = 0). The Diode block cannot be connected in series with an inductor, a current source, or an open circuit, unless its snubber circuit is in use.
Use the powergui block to specify either continuous simulation
or discretization of your electrical circuit containing diodes. When
using a continuous model, the
ode23tb solver with
a relative tolerance of 1e-4 is recommended for best accuracy and
The inductance Lon is forced to 0 if you choose to discretize your circuit.
Simulation produces the following results.
 Rajagopalan, V., Computer-Aided Analysis of Power Electronic Systems, Marcel Dekker, Inc., New York, 1987.
 Mohan, N., T.M. Undeland, and W.P. Robbins, Power Electronics: Converters, Applications, and Design, John Wiley & Sons, Inc., New York, 1995.