Three-Level Bridge

Implement three-level neutral point clamped (NPC) power converter with selectable topologies and power switching devices

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Simscape / Electrical / Specialized Power Systems / Power Electronics

Description

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.

Examples

AC/DC Three-Level PWM Converter

The operation of an AC-DC three-level PWM Converter.

• Open Model

Assumptions and Limitations

This block does not model turn-on and turn-off times (Fall time, Tail time) of power switching devices.

Ports

Input

g — Gating signal to control converter

vector of 4, 8, or 12 elements

Vectorized gating signal that contains 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.

Number of bridge arms	Pulse Vector of Input g
1	[Q1a,Q2a,Q3a,Q4a]
2	[Q1a,Q2a,Q3a,Q4a,Q1b,Q2b,Q3b,Q4b]
3	[Q1a,Q2a,Q3a,Q4a,Q1b,Q2b,Q3b,Q4b,Q1c,Q2c,Q3c,Q4c]

Note

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.

Conserving

A — Phase A terminal

specialized electrical

Specialized electrical conserving port associated with the phase A terminal.

B — Phase B terminal

specialized electrical

Specialized electrical conserving port associated with the phase B terminal.

C — Phase C terminal

specialized electrical

Specialized electrical conserving port associated with the phase C terminal.

N — Neutral terminal

specialized electrical

Specialized electrical conserving port associated with the neutral terminal.

+ — Positive terminal

specialized electrical

Specialized electrical conserving port associated with the positive terminal.

- — Negative terminal

specialized electrical

Specialized electrical conserving port associated with the negative terminal.

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink^® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Number of bridge arms — Number of bridge arms

3 (default) | 1 | 2

Number of bridge arms.

Snubber resistance Rs (Ohms) — Snubber resistance

1e5 (default) | positive scalar

Snubber resistance, in ohms. Set the snubber resistance to inf to eliminate the snubbers.

Snubber capacitance Cs (F) — Snubber capacitance

inf (default) | nonnegative scalar

Snubber capacitance, in farads. Set the Snubber capacitance Cs (F) parameter to 0 to eliminate the snubbers, or to inf to 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 — Power electronic device in bridge

GTO / Diodes (default) | MOSFET / Diodes | IGBT / Diodes | Ideal switches

Type of power electronic device to use in the bridge

Internal resistance Ron (Ohms) — Forward voltage across diode

1e-3 (default) | nonnegative scalar

Internal resistance of the selected devices and diodes, in ohms (Ω).

Forward voltages [Device Vf(V), Diode Vfd(V)] — Forward voltage across diode

[ 0 0 ] (default) | vector of two nonnegative values

Forward voltage of the selected devices (for GTO or IGBT only) and of the anti-parallel and clamping diodes, in volts

Dependencies

To enable this parameter, set Power electronic device to GTO/Diodes or IGBT / Diodes.

Measurements — Forward voltage across diode

None (default) | All device currents | Phase-to-Neutral and DC voltages | All voltages and currents

Select All device currents to 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.

Select Phase-to-Neutral and DC voltages to measure the terminal voltages (AC and DC) of the Three-Level Bridge block.

Select All voltages and currents to 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.

Measurement	Label (for GTO, IGBT, MOSFET Devices)
Device currents	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
Terminal voltages	Uan:, Ubn:, Ucn:, Udc+:, Udc-:

Measurement	Label (for Ideal Switch Device)
Device currents	Isw1a, Isw2a, Isw3a, Isw1b, Isw2b, Isw3b, Isw1c, Isw2c, Isw3c
Terminal voltages	Uan:, Ubn:, Ucn:, Udc+:, Udc-:

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a