Network Coupler (Thermal Mass)

Split network at a thermal connection

Since R2022a

• 

Libraries:
Simscape / Utilities / Network Couplers

Description

The Network Coupler (Thermal Mass) block uses a thermal mass to break a network connection. If your existing network has a suitable thermal mass already modeled, then replace it with the network coupler block. Otherwise, introduce a new thermal mass to the system using the Network Coupler (Thermal Mass) block.

Both of the port interfaces of the Network Coupler (Thermal Mass) block are implemented as temperature sources. Therefore, you cannot connect this block directly to a thermal mass or other temperature source because this would cause an Index-2 topology (for more information, see Avoiding Numerical Simulation Issues).

To facilitate working with models that contain arrays of thermal nodes, such as Simscape™ Battery™ models, the Port 1 Interface and Port 2 Interface subsystems contain custom blocks, such as Controlled Temperature Source or Heat Flow Rate Sensor. These custom blocks are based on the equivalent Foundation library blocks but are modified to support vectorized thermal nodes. The source files for these custom blocks are located in the following package directory:

matlabroot/toolbox/physmod/simscape/library/m/+foundation/+internal/+couplers/+thermal

where matlabroot is the MATLAB^® root directory on your machine, as returned by entering

matlabroot

at the MATLAB command prompt. The package contains source files for heat flow and temperature sources and sensors and a thermal reference with array support. You can use these blocks to customize your network coupler configuration.

Working with the Block on the Model Canvas

When you add the block to your model and double-click it, the Network Coupler (Thermal Mass) subsystem opens.

The Port 1 Interface block contains the dynamics that break the algebraic loop. Double-click this block to set all of the Network Coupler (Thermal Mass) subsystem parameters and view the derived values.

The rate transition blocks are, by default, commented through. Uncomment them if at least one of the coupled networks is running fixed step.

Using the Derived Values to Estimate Block Parameters

On the Analysis tab of the Port 1 Interface block dialog box, the Derived values section contains a list of recommended values that you can use when specifying block parameters. For example, use the Recommended max discrete sample time (s) derived value to verify that your Port 1 network discrete sample time (s) and Port 2 network discrete sample time (s) parameter values are within acceptable limits.

The derived values list is based on the chosen block configuration.

If both networks are running variable step, then the Analysis tab is empty, and there are no restrictions on the thermal mass value you specify.

If one or both networks are running fixed step, then the Analysis tab provides assistance on selecting a suitable thermal mass value, by asking you for an approximate thermal conductance value for the connected networks. If the thermal conductances of the two networks differ, provide the higher value. The Update button then provides a maximum recommended discrete sample time to use.

Examples

Configuring an EV Simulation for Multirate HIL

An electric vehicle model suitable for multirate Hardware-In-the-Loop (HIL) deployment. The example uses the Simscape™ Network Couplers Library to split the model into separate Simulink® subsystems that can be deployed at different sample rates. This allows you to run parts of the system (for example thermal components) with a slower sample time thereby reducing overall computational cost.

Open Model

Ports

Conserving

1 — Connect this port to the variable-step network, or to the fixed-step network with the smaller sample time

thermal | thermal node array

If one of the coupled networks is running variable step, connect it to port 1 of the Network Coupler (Thermal Mass) block. If both networks are running fixed step, connect this port to the network with the smaller sample time. If both networks are running variable step, or fixed step with the same step size, then the block polarity does not matter.

2 — Connect this port to the fixed-step network with the larger sample time

thermal | thermal node array

If one of the coupled networks is running variable step, connect port 2 of the Network Coupler (Thermal Mass) block to the fixed-step network. If both networks are running fixed step, connect this port to the network with the larger sample time.

Parameters

Main

Thermal node array size — Specify number of thermal nodes

1 (default) | positive integer

Specify the size of the thermal node array connected to the two thermal ports, 1 and 2. Because the top-level subsystem is unmasked, you need to set this parameter to the same value both for Port 1 Interface and Port 2 Interface blocks.

If you are breaking a regular thermal connection, leave the default value of 1 unchanged. However, some models use arrays of thermal nodes, for example, to connect a battery pack modeled using Simscape Battery to a corresponding cooling plate. In this case there are multiple thermal nodes in the battery pack that have corresponding thermal nodes on the cooling plate. You can use the Network Coupler (Thermal Mass) block to separate the two networks, to use a slower sample time for the thermal part and a faster one for the electrical part. Using the Network Coupler (Thermal Mass) block in such a model helps speed up desktop simulation and makes it easier to deploy the model to real-time hardware.

Thermal mass (J/K) — Specify thermal mass value

100 (default) | positive scalar

Specify the thermal mass value. Calculate this value by using the Mass and Specific heat parameters from the Thermal Mass block being replaced. The Analysis tab also provides assistance on selecting a suitable thermal mass value. For more information, see Using the Derived Values to Estimate Block Parameters.

Sampling type — Select sampling types scenario for coupled networks

Variable step at ports 1 and 2 (default) | Variable step at port 1 and fixed step at port 2 | Fixed step both ports with common sample time | Fixed step both ports with faster sampling at port 1

Select how the coupled networks are sampled:

• Variable step at ports 1 and 2 — Both networks are variable-step.

• Variable step at port 1 and fixed step at port 2 — Network 1 is variable-step and Network 2 is fixed-step.

• Fixed step both ports with common sample time — Both networks are fixed-step, with the same step size.

• Fixed step both ports with faster sampling at port 1 — Both networks are fixed-step, with different step sizes.

Port 1 network discrete sample time (s) — Specify sample time for Network 1

0.02 (default) | positive scalar

Specify sample time for Network 1, in seconds.

Dependencies

To enable this parameter, set the Sampling type parameter to Fixed step both ports with common sample time or Fixed step both ports with faster sampling at port 1.

Port 2 network discrete sample time (s) — Specify sample time for Network 2

0.1 (default) | positive scalar

Specify sample time for Network 2, in seconds.

Dependencies

To enable this parameter, set the Sampling type parameter to Variable step at port 1 and fixed step at port 2 or Fixed step both ports with faster sampling at port 1.

Use prediction when connecting fixed step to variable step — Lets you enable the prediction (discrete->continuous) algorithm

off (default) | on

Select this check box to enable the prediction (discrete->continuous) algorithm. For more information, see Prediction and Smoothing.

Dependencies

To display this option, set the Sampling type parameter to Variable step at port 1 and fixed step at port 2.

Use smoothing when connecting variable step to fixed step — Lets you enable the smoothing (continuous->discrete) algorithm

off (default) | on

Select this check box to enable the smoothing (continuous->discrete) algorithm. For more information, see Prediction and Smoothing.

Dependencies

To display this option, set the Sampling type parameter to Variable step at port 1 and fixed step at port 2.

Smoothing time constant (s) — Specify time constant for the first-order filter

0.01 (default) | positive scalar

Specify time constant, in seconds, for the first-order filter that the smoothing algorithm uses to remove unwanted high-frequency information.

Dependencies

To enable this parameter, select the Use smoothing when connecting variable step to fixed step check box.

Use prediction when connecting slow to fast sample times — Lets you enable the prediction (slow->fast) algorithm

off (default) | on

Select this check box to enable the prediction (slow->fast) algorithm. For more information, see Prediction and Smoothing.

Dependencies

To display this option, set the Sampling type parameter to Fixed step both ports with faster sampling at port 1.

Use smoothing when connecting fast to slow sample times — Lets you enable the smoothing (fast->slow) algorithm

off (default) | on

Select this check box to enable the smoothing (fast->slow) algorithm. For more information, see Prediction and Smoothing.

Dependencies

To display this option, set the Sampling type parameter to Fixed step both ports with faster sampling at port 1.

Number of samples over which to smooth — Specify number of samples for averaging

1 (default) | positive scalar

The smoothing algorithm works by averaging the last N samples. You specify N by using this parameter.

Dependencies

To enable this parameter, select the Use smoothing when connecting fast to slow sample times check box.

Analysis

Approximate connected network thermal conductance (W/K) — Specify approximate thermal conductance of connected network

1 (default) | positive scalar

Specify approximate thermal conductance of the connected network, in W/K. If the thermal conductances of the two networks differ, provide the higher value.

Dependencies

To enable this parameter, set the Sampling type parameter to Variable step at port 1 and fixed step at port 2, Fixed step both ports with common sample time, or Fixed step both ports with faster sampling at port 1.

For information on how to use the Derived values section, see Using the Derived Values to Estimate Block Parameters.

Initial Conditions

Initial temperature (K) — Specify initial temperature of the thermal mass

300 (default) | positive scalar

Specify initial condition for the thermal mass temperature, in K.

Extended Capabilities

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

Version History

Introduced in R2022a

R2023b: Break connections between arrays of thermal nodes

The Network Coupler (Thermal Mass) block now supports arrays of thermal nodes. The new parameter, Thermal node array size, lets you specify the array size. If you look under mask, the Port 1 Interface and Port 2 Interface subsystems contain custom blocks that support vectorized thermal nodes, instead of the regular Foundation library thermal blocks.

This change has no compatibility impact. The default value of the Thermal node array size parameter corresponds to a regular thermal connection. If you open an existing model containing this block, the simulation results are the same as in previous releases.