variable duty ratio to a switch at different time intervals

I want to supply a gate pulse to an IGBT switch in DC-DC converter with a duty ratio of 40% from 0 to 2 seconds and 2 to 4 seconds with simulation time of 6 seconds and i want to disconnect the gate pulse to switch from 4 to 6 seconds. how to do this in simulink. The switching frequency of IGBT switch is 20 kHZ.

[Manikanta Aditya]

Generate ideal, time varying pulse signal - Simulink (mathworks.com)

[Manikanta Aditya]

This block allows you to generate ideal modulated pulse signals with variable duty cycles.

[KESARI HANUMANTHU]

thanks for your help sir. but in my simulink model i have both AC and DC loads. DC load (Resistive) is connected at the output of DC-DC converter and should be switched ON upto 4 seconds based on the connection of AC loads. at 4 seconds i will further increase the AC load so that there should not be any power to the DC side. i mean i have to turn-off the gate pulse to the switch used in DC-DC converter. simulation stop time is 6 seconds. so from 4 to 6 seconds, DC load should be disconnected. remaining time (0-4 seconds), the duty ratio of the switch is 40 % and the switching frequency is 20 kHZ. could you please answer to my question how to do this? power gui used is dicrete with sampling time of 1e-6

[Manikanta Aditya]

To control an IGBT in a DC-DC converter with a variable duty cycle using Simulink:

• Add a Pulse Generator block to your model.
• Set Parameters in the Pulse Generator block:

% Pulse Type: Square
% Amplitude: 1 (or desired gate pulse amplitude)
% Period: (1/20000) seconds (for 20 kHz switching frequency)
% Pulse Width (% of period): 40 (for 40% duty ratio initially)
% Phase delay: 0

• Configure Signal Attributes: Choose "Time-based" pulse type.
• Define Variable Duty Ratio in Pulse Type Attributes:

% Time vector: ([0, 2, 4, 6]) seconds (time intervals)
% Duty cycle vector: ([0.4, 0.4, 0, 0]) (40% duty ratio from 0 to 4 seconds, then 0% from 4 to 6 seconds)

This setup achieves a variable duty cycle, transitioning from active switching to an off state.

[Fangjun Jiang]

@Manikanta Aditya, which Pulse Generator block are you referring to? I didn't find the place to "Define Variable Duty Ratio in Pulse Type Attributes".

[Manikanta Aditya]

I meant the Pulse Generator block in Simulink that allows defining a variable duty ratio based on time.

Answer 1

[Fangjun Jiang]

I assume this is in Simulink. You can use an AND logic block or Product block to multiply two signals. One is the regular 40% duty cycle PWM all the time, the other is this On/Off signal based on pre-determined timing or based on event by other Simulink signal.

[KESARI HANUMANTHU]

do i need to give regular 40% duty cycle PWM all the time using pulse generator block attached. how to give this On/Off signal based on pre-determined timing or based on event by other Simulink signal. i mean do i need to use signal builder kind?

[KESARI HANUMANTHU]

thanks a lot sir. it worked out.

[Fangjun Jiang]

You could use a Signal Builder block. Or use a Switch block, before t<4, pass the PWM. After that, switch to 0.