Powerstage Protection Unit

Purpose

Provide safety features for PWM outputs.

Description

../../_images/powerstage.svg

The Powerstage Protection Unit enables PWM outputs to be switched to a safe state. The safe state is active while a logic high level is detected on one of the fault detection inputs (digital inputs or trip block input). The Powerstage Protection Unit also enters safe state at the start of the simulation if the Reset behavior parameter is set to Rising edge at ‘en’ block input, otherwise the initial state depends on the state of the fault detection inputs.

It is possible to configure whether normal operation should be resumed either on the rising edge of a model signal or automatically when the fault detection inputs become 0. The output of the Powerstage Protection Unit is 0 when the unit is in safe state, otherwise 1. The safe state of the PWM signals is configured in the PWM block.

An unconfigured Powerstage Protection Unit (for which there is no block in the simulation model) is automatically set to normal operating mode when the simulation is started. Since no inputs are configured, it never enters the safe state.

Parameters

Protection unit: The Powerstage Protection Unit to configure.
Tripping via block input: If set to enabled, safe state is reached when a non-zero signal is detected on the trip block input. The block input is hidden when this parameter is set to disabled.
Tripping via digital input(s): Configures the digital inputs which are monitored. The Powerstage Protection Unit switches to safe state while a high input is detected on one of the digital inputs. The parameter can be either a scalar or a vector with up to three input signal indices. If left empty or an empty vector is specified, no digital input is monitored.
Digital input characteristic: Specifies whether an internal pull-up or pull-down resistor is connected to the digital inputs.
Reset behavior: Specifies when to resume normal operation. If set to Rising edge at ‘en’ block input the Powerstage Protection Unit waits for a rising edge on the en block input after all fault detection inputs are 0 before resuming normal operation. If set to Automatic, normal operation resumes when all fault detection inputs are 0, ignoring the en model input.

Inputs

en: A rising edge on the en block input resumes normal operation if all fault detection inputs (digital inputs and trip block input) are 0. This input is hidden when the parameter Reset behavior is set to Automatic.
trip: Any value other than 0 on the trip block input switches the Powerstage Protection Unit into safe state. This input is hidden when the parameter Trip via block input is set to disabled.