Non-Inverting Buck/Boost Converter Question

[Nabeel]

Function of the Circuit:
• Provide a constant voltage of 3.7V at the load for battery charging when there is an input ranging from 0V to 5V.
• When SW1 driven by PWM 1 and SW2 is always OFF, the device will work in Buck Mode. That is if input voltage goes above 3.7V.
• When SW1 is always ON and SW2 is driven by PWM 2, the device will work in Boost Mode. That is if input voltage is below 3.7V.

Question:
How to create a feedback system at the output which will cause the output to stay constant at 3.7V?
• The circuit have to boost the voltage to 3.7V if the voltage at the input is below 3.7 V
• The circuit have to buck the voltage to 3.7V if the voltage at the input is above 3.7V

Note: The circuit is attached in the thread.

 

[Baluncore]

The usual solution to this situation is to first boost to say +12V, then buck that to +3.7V.

The reason for using +12V rather than +5V is that efficiency is better with the higher intermediate voltage and the capacitor between the stages can be smaller.

You have not specified the charge current output required at +3.7V.

 

[NascentOxygen]

Function of the Circuit:
• Provide a constant voltage of 3.7V at the load for battery charging when there is an input ranging from 0V to 5V.

As it is required to supply 3.7V output even when there is no input, you'll be deriving full power from another source under some conditions.

 

[berkeman]

Function of the Circuit:
• Provide a constant voltage of 3.7V at the load for battery charging when there is an input ranging from 0V to 5V.
• When SW1 driven by PWM 1 and SW2 is always OFF, the device will work in Buck Mode. That is if input voltage goes above 3.7V.
• When SW1 is always ON and SW2 is driven by PWM 2, the device will work in Boost Mode. That is if input voltage is below 3.7V.

Question:
How to create a feedback system at the output which will cause the output to stay constant at 3.7V?
• The circuit have to boost the voltage to 3.7V if the voltage at the input is below 3.7 V
• The circuit have to buck the voltage to 3.7V if the voltage at the input is above 3.7V

Note: The circuit is attached in the thread.

Since this is your schoolwork problem, you need to show a fair amount of initial effort, before we can be of tutorial help. Can you show us some techniques that can be used for this problem?

 

[rezeew]

I would like to provide the following response to the Non-Inverting Buck/Boost Converter question:

The function of this circuit is to provide a constant voltage of 3.7V at the load for battery charging, regardless of the input voltage ranging from 0V to 5V. This is achieved by utilizing a feedback system that switches between Buck and Boost modes based on the input voltage.

To create a feedback system, the circuit uses two switches (SW1 and SW2) controlled by two separate PWM signals (PWM 1 and PWM 2). When SW1 is driven by PWM 1 and SW2 is always OFF, the circuit operates in Buck mode, meaning that if the input voltage goes above 3.7V, the circuit will reduce the voltage to 3.7V at the output. On the other hand, when SW1 is always ON and SW2 is driven by PWM 2, the circuit operates in Boost mode, which boosts the voltage to 3.7V if the input voltage is below 3.7V.

To ensure that the output stays constant at 3.7V, the feedback system continuously monitors the output voltage and adjusts the switching between Buck and Boost modes accordingly. If the output voltage drops below 3.7V, the feedback system will switch to Boost mode to increase the voltage. Similarly, if the output voltage goes above 3.7V, the feedback system will switch to Buck mode to reduce the voltage.

Overall, the feedback system in this circuit plays a crucial role in maintaining a constant output voltage of 3.7V, regardless of the input voltage. This is important for battery charging, as a stable and controlled voltage is necessary for efficient and safe charging.