Implement universal power converter with selectable topologies and power electronic devices
Simscape / Electrical / Specialized Power Systems / Power Electronics
The Universal Bridge block implements a universal three-phase power converter that consists of up to six power switches connected in a bridge configuration. The type of power switch and converter configuration are selectable from the dialog box.
The Universal Bridge block allows simulation of converters using both naturally commutated (or line-commutated) power electronic devices (diodes or thyristors) and forced-commutated devices (GTO, IGBT, MOSFET).
The Universal Bridge block is the basic block for building two-level voltage-sourced converters (VSC).
The device numbering is different if the power electronic devices are naturally commutated or forced-commutated. For a naturally commutated three-phase converter (diode and thyristor), numbering follows the natural order of commutation:
For the case of a two-phase diode or thyristor bridge, and for any other bridge configuration, the order of commutation is the following:
MOSFET-Diode and Ideal Switch bridges:
g — Gate input
The gate input for the controlled switch devices. The pulse ordering in the vector of the gate signals corresponds to the switch number indicated in the six circuits shown in the Description section. For the diode and thyristor bridges, the pulse ordering corresponds to the natural order of commutation. For all other forced-commutated switches, pulses are sent to upper and lower switches of phases A, B, and C.
Pulse Vector of Input g
A — Phase A
Specialized electrical conserving port associated with phase A.
B — Phase B
Specialized electrical conserving port associated with phase B.
C — Phase C
Specialized electrical conserving port associated with phase C.
+ — Positive terminal
Specialized electrical conserving port associated with the positive terminal.
- — Negative terminal
Specialized electrical conserving port associated with the negative terminal.
Number of bridge arms — Number of bridge arms
1 (default) |
2 to get a single-phase converter (two
or four switching devices). Set to
3 to get a three-phase converter
connected in Graetz bridge configuration (six switching devices). Default is
Snubber resistance Rs (Ohms) — Snubber resistance
The snubber resistance, in ohms (Ω). Default is
1e5. Set the
Snubber resistance Rs parameter to
to eliminate the snubbers from the model.
Snubber capacitance Cs (F) — Snubber capacitance
The snubber capacitance, in farads (F). Default is
inf. Set the
Snubber capacitance Cs parameter to
eliminate the snubbers, or to
inf to get a resistive snubber.
When you are using the continuous solver you can eliminate snubbers in all power electronic devices if you select the Disable snubbers in switching devices option in the Preference tab of the Powergui block
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 — Type of power electronic device
Diodes (default) |
GTO / Diodes |
MOSFET / Diodes |
IGBT / Diodes |
Ideal Switches |
Switching-function based VSC |
Average-model based VSC
Select the type of power electronic device to use in the bridge. Default is
When you select
Switching-function based VSC, a
switching-function voltage source converter type equivalent model is used, where switches are
replaced by two voltage sources on the AC side and a current source on the DC side. This
model uses the same firing pulses as for other power electronic devices and it correctly
represents harmonics normally generated by the bridge.
When you select
Average-model based VSC, an average-model
type of voltage source converter is used to represent the power-electronic switches. Unlike
the other power electronic devices, this model uses the reference signals (uref) representing
the average voltages generated at the ABC terminals of the bridge. This model does not
represent harmonics. It can be used with larger sample times while preserving the average
power_sfavg for an
example comparing these two models to an Universal Bridge block using IGBT/Diode device.
Ron (Ohms) — Internal resistance
Internal resistance of the selected device, in ohms (Ω). Default is
Lon (H) — Internal inductance
Internal inductance, in henries (H), for the diode or the thyristor device. Default is
0. When the bridge is discretized, the Lon parameter must be set to
Forward voltages [ Device Vf(V) , Diode Vfd(V)] — Forward voltages
[ 0 0 ] (default)
This parameter is available when the selected Power electronic
Forward voltages, in volts (V), of the forced-commutated devices (GTO, MOSFET, or IGBT)
and of the antiparallel diodes. Default is
[ 0 0 ].
Forward voltage Vf (V) — Forward voltage across the device
This parameter is available only when the selected Power
electronic device is
Forward voltage, in volts (V), across the device when it is conducting. Default is
Measurements — Measurement type
None (default) |
Device voltages |
Device currents |
UAB UBC UCA UDC voltages |
All voltages and currents
Device voltages to measure the voltages across the six
power electronic device terminals.
Device currents to measure the currents flowing
through the six power electronic devices. If antiparallel diodes are used, the measured
current is the total current in the forced-commutated device (GTO, MOSFET, or IGBT) and in
the antiparallel diode. A positive current therefore indicates a current flowing in the
forced-commutated device and a negative current indicates a current flowing in the diode. If
snubber devices are defined, the measured currents are the ones flowing through the power
electronic devices only.
UAB UBC UCA UDC voltages to measure the terminal
voltages (AC and DC) of the Universal Bridge block.
All voltages and currents to measure all voltages and
currents defined for the Universal Bridge block.
Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurements menu of the Multimeter block, the measurement is identified by a label followed by the block name.