Diode
Purpose
Ideal diode with optional forward voltage and on-resistance
Library
Electrical / Power Semiconductors
Description
The Diode is a semiconductor device controlled only by the voltage across it and the current through the device. The Diode model is basically an ideal switch that closes when the voltage between anode and cathode becomes positive and opens when the current through the component becomes negative. In addition to the ideal switch, a forward voltage and an on-resistance may be specified. These parameters may either be scalars or vectors corresponding to the implicit width of the component. If unsure set both values to 0.
Parameters
The following parameters may either be scalars or vectors corresponding to the implicit width of the component:
- Forward voltage
Additional dc voltage \(V_\mathrm{f}\) in volts \((\mathrm{V})\) between anode and cathode when the diode is conducting. The default is
0.- On-resistance
The resistance \(R_\mathrm{on}\) of the conducting device, in ohms \((\Omega)\). The default is
0.- Thermal description
Switching losses, conduction losses and thermal equivalent circuit of the component. For more information see chapter Thermal Modeling. If no thermal description is given, the losses are calculated based on the voltage drop \(v_\mathrm{on} = V_\mathrm{f} + R_\mathrm{on}\cdot i\).
- Thermal interface resistance
The thermal resistance of the interface material between case and heat sink, in \((\mathrm{K}/\mathrm{W})\). The default is
0.- Number of parallel devices
This parameter is used to simulate the effect of connecting multiple identical devices in parallel while adding only one single switch element to the electrical system equations. Other component parameters such as the Thermal description, the Thermal interface resistance and also the electrical On-resistance refer to the characteristics of an individual device, while the calculated losses and other probe signals refer to the sum over all devices.
If \(N_\mathrm{p}\) is the number of parallel devices, each device will conduct \(1/N_\mathrm{p}\) of the total current through the component, and the total component loss will be \(N_\mathrm{p}\) times the loss of an individual device. The effective electrical on-resistance and the effective thermal interface resistance of the component are also \(1/N_\mathrm{p}\) times the respective parameter values. The default is
1.Example Model
See the example model “Thermal Modelling with Parallel Devices”.
Find it in PLECS under Help > PLECS Documentation > List of Example Models.
- Initial temperature
This parameter is used only if the device has an internal thermal impedance and specifies the temperature of the thermal capacitance at the junction at simulation start. The temperatures of the other thermal capacitances are initialized based on a thermal “DC” analysis. If the parameter is left blank, all temperatures are initialized from the external temperature. See also Temperature Initialization.
- Switch model (CPU code generation)
Select the switch model in the generated code.
- Fundamental grid frequency (Hz)
Frequency where non-ideal switches in the open state have increased series impedance. The default is
0.
Note
Under blocking conditions the diode voltage is negative. Hence you should define the turn-on and turn-off loss tables for negative voltages. See chapter Diode Losses for more information.
Probe Signals
- Diode voltage
The voltage measured between anode and cathode.
- Diode current
The current through the diode flowing from anode to cathode.
- Diode conductivity
Conduction state of the internal switch. The signal outputs \(0\) when the diode is blocking, and \(1\) when it is conducting.
- Diode junction temperature
Temperature of the first thermal capacitor in the equivalent Cauer network.
- Diode conduction loss
Continuous thermal conduction losses in watts \((\mathrm{W})\). Only defined if the component is placed on a heat sink.
- Diode switching loss
Instantaneous thermal switching losses in joules \((\mathrm{J})\). Only defined if the component is placed on a heat sink.