Implement three-level neutral point clamped (NPC) power converter with selectable topologies and power switching devices
Simscape / Electrical / Specialized Power Systems / Power Electronics
The Three-Level Bridge block implements a three-level power converter that consists of one, two, or three arms of power switching devices. Each arm consists of four switching devices along with their antiparallel diodes and two neutral clamping diodes as shown in the figure below.
The type of power switching device (IGBT, GTO, MOSFET, or ideal switch) and the number of arms (one, two, or three) are selectable from the dialog box. When the ideal switch is used as the switching device, the Three-Level Bridge block implements an ideal switch bridge having a three-level topology as shown in the following figure.
- Number of bridge arms
Determine the bridge topology: one, two, or three arms. Default is
- Snubber resistance Rs
The snubber resistance, in ohms (Ω). Default is
1e5. Set the Snubber resistance Rs parameter to
infto eliminate the snubbers from the model.
- Snubber capacitance Cs
The snubber capacitance, in farads (F). Default is
inf. Set the Snubber capacitance Cs parameter to
0to eliminate the snubbers, or to
infto get a resistive snubber.
To eliminate snubbers in all power electronic devices when using a continuous solver, select the Disable snubbers in switching devices option in the Powergui Preferences tab.
When your system is discretized, you can simulate power electronic devices with virtually no snubbers by specifying purely resistive snubbers with a very large resistance, thus producing negligible leakage currents. The bridge operates satisfactorily with purely resistive snubbers.
- Power electronic device
Select the type of power electronic device to use in the bridge. Default is
- Internal resistance Ron
Internal resistance of the selected devices and diodes, in ohms (Ω). Default is
- Forward voltages [Device Vf, Diode Vfd]
The forward voltage of the selected devices (for GTO or IGBT only) and of the antiparallel and clamping diodes, in volts. Default is
[ 0 0 ].
All device currentsto measure the current flowing through all the components (switching devices and diodes). If the snubber devices are defined, the measured currents are those flowing through the power electronic devices only.
Phase-to-Neutral and DC voltagesto measure the terminal voltages (AC and DC) of the Three-Level Bridge block.
All voltages and currentsto measure all voltages and currents defined for the Three-Level Bridge block.
Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurement list box of the Multimeter block, the measurement is identified by a label followed by the block name.
Label (for GTO, IGBT, MOSFET Devices)
IQ1a, IQ2a, IQ3a, IQ4a,
IQ1b, IQ2b, IQ3b, IQ4b,
IQ1c, IQ2c, IQ3c, IQ4c,
ID1a, ID2a, ID3a, ID4a, ID5a, ID6a,
ID1b, ID2b, ID3b, ID4b, ID5b, ID6b,
ID1c, ID2c, ID3c, ID4c, ID5c, ID6c
Label (for Ideal Switch Device)
Isw1a, Isw2a, Isw3a, Isw1b, Isw2b, Isw3b,
Isw1c, Isw2c, Isw3c
Inputs and Outputs
The input g is a vectorized gating signal containing pulses to control the power electronic devices of the bridge. The length of the input vector depends on the number of arm you specified for the bridge topology.
Pulse Vector of Input g
In the case of the ideal switch converter, the Q1 pulse is sent to Sw1, the Q4 pulse to Sw2, and a logical AND operation is performed on the Q2 and Q3 pulses and the result sent to Sw3.
Assumptions and Limitations
Turn-on and turn-off times (Fall time, Tail time) of power switching devices are not modeled in the Three-Level Bridge block.
power_3levelVSC example illustrates the use of the Three-Level Bridge block.