Description

The PWM Synchronize Ain functionality of the OPAL-RT Board driver provides the simulation with the possibility of outputting pulse width modulated (PWM) values through the digital output channels of the OP5354 or OP5360-2 modules installed on the simulator. These signals are then used to synchronize analog input signals going through the analog input channels of the OP5340 modules installed on the simulator.

In the case of the OP4200 chassis, the OP5360-2 used is incorporated into the I/O cassette with ID OP4260-1.

In order to generate valid PWM signals, only the duty cycle input is required. However, the Enable signal must be set at 1 to activate PWM generation. The shape of the PWM signals is defined by their frequency, phase, symmetricity and in the case of complementary signals, the dead time between them. There is also an option to set a delay between the model start time and the start of the PWM generation. These parameters are customizable for each PWM signal. A detailed description for them is given in the Signals Configuration section below.

The duty cycles must be between 0 and 1.

Usage

Once the bitstream configuration file has been parsed, the location of the digital output modules becomes visible to the user. The channels of the modules are in groups of eight. By clicking on each group, the user has access to the configurable options of the group.

Verifying that a bitstream has the PWM Synchronize AIn feature is done in the channel group configuration section. If the bitstream has this feature, the Digital type field is marked as Synchronize Analog and is displayed as a non-editable field (greyed out).

Channel Group Configuration

Signal Configuration

Channels in pulse width modulated output groups have the following parameters to configure:

Wave Mode	This parameter sets the generation pattern of the carrier wave of a signal. If the generation mode is set to Symmetric, the carrier is a triangular waveform. An Asymmetric generation mode corresponds to a sawtoothed carrier waveform. As a result, a symmetric PWM signal has the same amount of time between the beginning of the period and the rising edge of its active phase as between the falling edge of the active phase and the end of the period. For an asymmetric PWM signal, the rising edge of the active phase will be aligned with the beginning of the period.
Update Time	This parameter allows the user to choose the time the duty cycle of the PWM signal would be updated. If Beginning is selected, the duty cycle is updated at the beginning of the PWM period. If Middle is selected, it's updated at the middle of the PWM period. If Both is selected, the duty cycle is updated at both the beginning and middle of the PWM period.
Model period ratio	This parameter allows the user to set the frequency of the PWM signal. The frequency of the PWM signal is given by 1 / (Timestep * ModelRatio). Timestep is timestep of the CPU model and ModelRatio is the Model period ratio parameter
Phase (deg)	This parameter is used to specify the phase of the PWM signal. Accepted values for this field are any floating-point values between 0 and 360.
Dead Time	This parameter is only visible if the Output complementary checkbox is selected.
The inclusion of dead time reduces the length of the active phase of the two complementary waveforms, thus reducing their duty cycle. The value in this field denotes an amount of time (in us) during which the two complementary signals remain in their inactive phases. Accepted values for this field are any floating-point values between 20e-6 and 0.

Characteristics and Limitations

For the connector pin assignments, the user should refer to the carrier documentation.

The current version of the pulse width modulated digital output functionality of the OPAL-RT Board driver has the following limitations:

• The duty cycle values must range between 0 and 1