Implement diode model
Simscape / Electrical / Specialized Power Systems / 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 block also contains a series Rs-Cs snubber circuit that can be connected in parallel with the diode device (between nodes A and K).
power_diode example illustrates a single pulse
rectifier consisting of a Diode block, an RL load, and an AC Voltage source
Assumptions and Limitations
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.
The inductance Lon is forced to 0 if you choose to discretize your circuit.
m — Measurement vector
Measurement vector containing two signals. You can demultiplex these signals by using the Bus Selector block provided in the Simulink library.
To enable this port, check the Show measurement port parameter.
a — Anode
Specialized electrical conserving port associated with the anode.
k — Cathode
Specialized electrical conserving port associated with the cathode.
Resistance Ron (Ohms) — Diode internal resistance
Diode internal resistance Ron, in ohms (Ω). Default is
0.001. The Resistance
Ron parameter cannot be set to
0 when the
Inductance Lon parameter is set
Inductance Lon (H) — Diode internal inductance
Diode internal inductance Lon, in henries (H). Default is
0. The Inductance
Lon parameter cannot be set to
0 when the
Resistance Ron parameter is set
Forward voltage Vf (V) — Diode forward voltage
Forward voltage of the diode device, in volts (V). Default is
Initial current Ic (A) — Initial current
Specifies an initial current flowing in the diode device. Default is
0. It is usually set to
0 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.
Snubber resistance Rs (Ohms) — Snubber resistance
Snubber resistance, in ohms (Ω). Default is
the Snubber resistance Rs parameter to
inf to eliminate the snubber from the model.
Snubber capacitance Cs (F) — Snubber capacitance
Snubber capacitance in farads (F). Default is
Set the Snubber capacitance Cs parameter to
0 to eliminate the snubber, or to
inf to get a resistive snubber.
Show measurement port — Measurement port visibility option
on (default) |
If selected, adds a Simulink output to the block returning the diode current and voltage. Default is selected.
 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.
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