# Half-Bridge (Ideal, Switching)

**Libraries:**

Simscape /
Electrical /
Semiconductors & Converters

## Description

The Half-Bridge (Ideal, Switching) block models a half-bridge
with ideal switches and a thermal port. To choose the ideal switching device, set the
**Switching device** parameter to either
`MOSFET`

, `IGBT`

, or
`GTO`

.

You can specify an integral protection diode for each switching device. An integral diode protects the semiconductor device by providing a conduction path for a reverse current. An inductive load can produce a high reverse-voltage spike when the semiconductor device suddenly switches off the voltage supply to the load.

**Note**

The `lastReverseRecoveryLoss`

variable in the simlog includes
the reverse recovery losses as a pulse with amplitude equal to the energy loss.
If you use a script to sum the total losses over a defined simulation period,
you must sum the pulse values at each pulse rising edge. Alternatively, you can
use the `ee_getPowerLossSummary`

and
`ee_getPowerLossTimeSeries`

functions
to extract conduction and switching losses from logged data.

Note that the `power_dissipated`

variable in the simlog does
not include switching losses as they are modeled as instantaneous events. The
`power_dissipated`

variable therefore just reports
instantaneous on-state losses.

### Equations

The protection diodes inside the half-bridge use the Lauritzen and Ma model to capture the charge dynamics effects. The defining equations are:

${i}_{RM}=\frac{{q}_{E}-{q}_{M}}{{T}_{M}}$ | (1) |

$\frac{d{q}_{M}}{dt}+\frac{{q}_{M}}{\tau}-\frac{{q}_{E}-{q}_{M}}{{T}_{M}}=0$ | (2) |

*i*is the diode peak reverse current._{RM}*q*is the junction charge._{E}*q*is the total stored charge._{M}*T*is the transit time._{M}*τ*is the carrier lifetime.

The block solves equation 2 at `t = 0`

and
*q _{M}* in steady-state:

${q}_{M}={i}_{RM}\tau -\tau \left({i}_{RM}-{i}_{F}\right)\mathrm{exp}\left(-\frac{t}{\tau}\right)=\tau {i}_{F}.$ | (3) |

At `t = 0`

and `q`

,
equation 1 is equal to: _{E} = 0

${i}_{RM}=\frac{-{q}_{M}}{{T}_{M}}.$ | (4) |

${i}_{RM}=\frac{-\tau}{{T}_{M}}{i}_{F},$ | (5) |

*i*is the starting forward current when measuring

_{F}*i*.

_{RM}Finally, the block calculates the reverse recovery energy,
*E _{rec}*, as:

$${E}_{rec}={\displaystyle {\int}_{{t}_{1}}^{{t}_{2}}{i}_{d}{v}_{d}dt}={\displaystyle {\int}_{n}^{{t}_{2}}{i}_{RM}exp\left(-\frac{t-{t}_{1}}{{\tau}_{rr}}\right){v}_{R}dt},$$ | (6) |

*i*is the current through the diode._{d}*v*is the voltage across the diode._{d}*τ*is the reverse recovery time._{rr}

Given
`t`

,
the total reverse recovery energy is:_{2}=*τ _{rr}*ln(10)

$${E}_{rec}=-0.9{\tau}_{rr}\frac{\tau}{{T}_{M}}{i}_{F}{v}_{R}=-0.9\frac{{\tau}^{2}}{\tau +{T}_{M}}{i}_{F}{v}_{R}.$$ | (7) |

### Predefined Parameterization

There are multiple available built-in parameterizations for the Half-Bridge (Ideal, Switching) block.

This pre-parameterization data allows you to set up the block to represent
components by specific suppliers. The parameterizations of these half-bridges match
the manufacturer data sheets. To load a predefined parameterization, double-click
the Half-Bridge (Ideal, Switching) block, click the **<click
to select>** hyperlink of the **Selected part**
parameter and, in the Block Parameterization Manager window, select the part you
want to use from the list of available components.

**Note**

The predefined parameterizations of Simscape™ components use available data sources for the parameter values. Engineering judgement and simplifying assumptions are used to fill in for missing data. As a result, expect deviations between simulated and actual physical behavior. To ensure accuracy, validate the simulated behavior against experimental data and refine component models as necessary.

For more information about pre-parameterization and for a list of the available components, see List of Pre-Parameterized Components.

## Assumptions and Limitations

The current change in the load is negligible. The inductance or the switching frequency are large enough so that the load current is constant between the switches.

The stray inductance of the circuit is negligible.

## Ports

### Input

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2021b**