Three-phase modular multilevel converter with series-connected powersubmodules (2024)

Three-phase modular multilevel converter with series-connected powersubmodules

Since R2020b

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Libraries:
Simscape / Electrical / Semiconductors & Converters / Converters

Description

The Modular Multilevel Converter (Three-Phase) blockmodels a three-phase modular multilevel converter. Each phase consists of two arms thatare implemented with a number of series-connected power submodules.

Each submodule consists of a half-bridge or full-bridge converter and acapacitor.

Half-Bridge Topology

Full-Bridge Topology

This blocks allows you to select the level of model fidelity by choosing between adetailed model with switching devices or an equivalent model. You can choose from theseswitching devices are:

GTO — Gate turn-off thyristor. For information about the I-V characteristic of the device, see GTO.
Ideal semiconductor switch — For information about the I-V characteristic of the device, see Ideal Semiconductor Switch.
IGBT — Insulated-gate bipolar transistor. For information about the I-V characteristic of the device, see IGBT (Ideal, Switching).
MOSFET — N-channel metal-oxide-semiconductor field-effect transistor. For information about the I-V characteristic of the device, see MOSFET (Ideal, Switching).
Thyristor — For information about the I-V characteristic of the device, see Thyristor (Piecewise Linear).
Averaged Switch — Semiconductor switch with an antiparallel diode. The control signal port G accepts values in the interval [0,1]. When G is equal to 0 or 1, the averaged switch is fully opened or fully closed respectively. The switch behaves similarly to the Ideal Semiconductor Switch block with an antiparallel diode. When G is between 0 and 1, the averaged switch is partly opened. You can average the pulse-width modulation (PWM) signal over a specified period. You can then undersample the model and use modulation waveforms instead of PWM signals.

Piecewise Constant Approximation in Averaged Switch for FPGA Deployment

If you set the Switching device parameter to Averaged switch and your model uses a partitioning solver, this block produces nonlinear partitions because the average mode equations include modes, G_sat that are functions of the input G. To make these equations compatible with hardware description language (HDL) code generation, and therefore FPGA deployment, set the Integer for piecewise constant approximation of gate input (0 for disabled) parameter to a value greater than 0. This block then treats the G_sat mode as a piecewise constant integer with a fixed range. This turns the previously nonlinear partitions to linear time varying partitions.

An integer value in the range [0,K], where K is the value of the Integer for piecewise constant approximation of gate input (0 for disabled), is now associated with each real value mode in the range [0,1]. The block computes the piecewise constant mode by dividing the original mode by K to normalize it back to the range [0,1]:

$\begin{array}{l} u_{I} = (f l o o r (u \cdot K)) \\ \hat{u} = \frac{u_{I}}{K} \end{array}$

Variables

To set the priority and initial target values for the block variables before simulation, use the Initial Targets section in the block dialog box or Property Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. You can specify nominal values using different sources, including the Nominal Values section in the block dialog box or Property Inspector. For more information, see System Scaling by Nominal Values.

Ports

Input

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G — Submodule gate control
matrix of physical signals

Physical signal port associated with the gate signal for allsubmodules of the modular multilevel converter, specified as amatrix.

If you set the Converter topology parameter toHalf-bridge, the signal is a vector oflength 12 * Nsm, where Nsm isthe Number of power submodules.

If you set the Converter topology parameter toFull-bridge, the signal is a vector oflength 24 * Nsm.

Dependencies

To enable this port, set Fidelity level toDetailed model - switching devices orEquivalent model -PWM-controlled.

ref — Submodule reference waveform
vector of physical signals

Physical signal port associated with the reference waveforms of the submodules,specified as a vector of length 6.

Dependencies

To enable this port, set Fidelity level toEquivalent model -waveform-controlled.

Output

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vc — Capacitor voltages
vector of physical signals

Physical signal port associated with the capacitor voltages for each submodule in themodular multilevel converter, returned as a vector.

Dependencies

To enable this port, set Capacitor voltagesto Instrumented.

Conserving

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+ — Positive terminal
electrical

Electrical conserving port associated with the positive terminal ofthe modular multilevel converter.

- — Negative terminal
electrical

Electrical conserving port associated with the negative terminal ofthe modular multilevel converter.

~ — Three-phase port
electrical

Expandable three-phaseelectrical port associated with the three-phase terminal ofthe modular multilevel converter.

Dependencies

To enable this port, set Electricalconnection to Composite three-phaseports.

a — a-phase
electrical

Electrical conserving port associated witha-phase.

Dependencies

To enable this port, set Electricalconnection to Expanded three-phaseports.

b — b-phase
electrical

Electrical conserving port associated withb-phase.

Dependencies

To enable this port, set Electricalconnection to Expanded three-phaseports.

c — c-phase
electrical

Electrical conserving port associated withc-phase.

Dependencies

To enable this port, set Electricalconnection to Expanded three-phaseports.

Parameters

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Main

Electrical connection — Electrical connection
`Composite three-phaseports` (default) | `Expanded three-phase ports`

Whether to have composite or expanded three-phase ports.

Converter topology — Converter topology
`Half-bridge` (default) | `Full-bridge`

Topology of the modular multilevel converter.

Fidelity level — Model fidelity
`Detailed model - switchingdevices` (default) | `Equivalent model - PWM-controlled` | `Equivalent model -waveform-controlled`

Level of fidelity of the model.

Capacitor voltages — Capacitor voltage instrumentation
`Instrumented` (default) | `Uninstrumented`

Whether to instrument the capacitor voltages.

Number of power submodules — Number of submodules
`1` (default) | positive scalar

Number of power submodules of the modular multilevel converter.

Capacitance — Submodule capacitance
`1e-7F` (default) | scalar | vector

Capacitance of a submodule. If you enter a vector, the vector must be of length6 * Nsm, where Nsm is theNumber of power submodules.

Capacitor effective series resistance — Capacitor effective series resistance
`1e-6Ohm` (default) | scalar | vector

Capacitor effective series resistance. If you enter a vector, the vector must be oflength 6 * Nsm, where Nsm isthe Number of power submodules.

Dependencies

To enable this parameter, set Fidelity levelto Detailed model - switching devices.

Arm inductance — Arm inductance
`1e-6H` (default) | scalar

Inductance of the arm.

Arm inductance series resistance — Arm inductance series resistance
`0Ohm` (default) | scalar

Arm inductance series resistance.

Capacitor initial voltage — Capacitor initial voltage
`500V` (default) | scalar | vector

Initial voltage of the capacitor. If you enter a vector, the vector must be of length6 * Nsm, where Nsm is theNumber of power submodules.

Switching Devices

This table shows how enabled parameters in the Switching Devicessettings depend on the Switching device that you select. Tolearn how to read the table, see Parameter Dependencies. To enable these settings, setFidelity level to Detailed model - switchingdevices.

Switching Devices Parameter Dependencies

Parameters andOptions
Switching device
`Ideal SemiconductorSwitch`	`GTO`	`IGBT`	`MOSFET`	`Thyristor`	`AveragedSwitch`
On-state resistance	Forward voltage	Forward voltage	Drain-source on resistance	Forward voltage	On-state resistance
Off-state conductance	On-state resistance	On-state resistance	Off-state conductance	On-state resistance
Threshold voltage	Off-state conductance	Off-state conductance	Threshold voltage	Off-state conductance
	Gate trigger voltage, Vgt	Threshold voltage		Gate trigger voltage, Vgt	Integer for piecewise constantapproximation of gate input (0 fordisabled)
	Gate turn-off voltage, Vgt_off			Holding current
	Holding current			Holding current