Could someone please assist me? My code for the buck-boost converter controller isn't working properly when I run it.

this is the Simulink model

[Danikha Shyken]

Here is the code:

function [q1, q2, q3, q4] = buckBoostController(inputVoltage)

% Constants for duty cycle and delay values

dutyCycleBoost = [85.71, 81.82, 60.00];

delayBoost = [51.444, 65.448, 144.000];

dutyCycleBuck = 47.37;

delayBuck = 170.532;

% Define the battery voltage

batteryVoltage = 1.8;

% Check input voltage to determine the mode (Boost, Buck, or Battery Voltage)

ind = inputVoltage == [0.3, 0.4, 1.2]; % Avoid repeating "inputVoltage == [0.3, 0.4, 1.2]"

if any(ind)

% Boost Mode

dutyCycle = dutyCycleBoost(ind);

delay = delayBoost(ind);

q1 = 1;

q2 = dutyCycle(1) / 100; % Add (1) to clearly define size

q3 = 0;

q4 = 1 - q2;

elseif inputVoltage == 2

% Buck Mode

dutyCycle = dutyCycleBuck;

delay = delayBuck;

q1 = dutyCycle / 100;

q2 = 0;

q3 = 1 - q1;

q4 = 1;

elseif inputVoltage == batteryVoltage

% Battery Voltage Mode

q1 = 1;

q2 = 0;

q3 = 0;

q4 = 0;

% Optionally, you can set dutyCycle and delay for this mode if needed.

else

error('Input voltage is out of the specified range.');

end

end

Can someone please help me improve this code to make it work as intended?

[Danikha Shyken]

In the code, I've already incorporated the calculated duty cycles and delays to enable the controller to operate automatically within an input voltage range of 0.3-2V. When the input voltage is either 0.3V, 0.4V, or 1.2V, the system will function in boost mode, and this is reflected in the MOSFET switching operations (represented by q1, q2, q3, q4). However, if the input voltage is 2V, the system will operate in buck mode. If there are no other sources available, the system will be powered by the battery that holds 1.8V. The desired output voltage is 1.8V.

Answer 1

[dpb]

<We already told you> this was going to be a problem but you didn't pay attention...

if inputVoltage == 0.3 || inputVoltage == 0.4 || inputVoltage == 1.2

is very problematical in doing exact comparisons with floating point values;

and

ind = inputVoltage == [0.3, 0.4, 1.2]; % Avoid repeating "inputVoltage == [0.3, 0.4, 1.2]"
if any(ind)

has the same issue.

[Danikha Shyken]

I revised the code as you suggested:

function [q1, q2, q3, q4] = buckBoostController(inputVoltage)

% Constants for duty cycle and delay values

dutyCycleBoost = [85.71, 81.82, 60.00];

delayBoost = [51.444, 65.448, 144.000];

dutyCycleBuck = 47.37;

delayBuck = 170.532;

% Define the battery voltage

batteryVoltage = 1.8;

% Constants for boost and buck voltages

BOOST_V = [0.3, 0.4, 1.2];

BUCK_V = 2.0;

% Check input voltage to determine the mode (Boost, Buck, or Battery Voltage)

isBoost = ismembertol(inputVoltage, BOOST_V);

isBuck = ismembertol(inputVoltage, BUCK_V);

if any(isBoost)

% Boost Mode

idx = find(isBoost);

dutyCycle = dutyCycleBoost(idx);

delay = delayBoost(idx);

q1 = 1;

q2 = dutyCycle(1) / 100; % Add (1) to clearly define size

q3 = 0;

q4 = 1 - q2;

elseif any(isBuck)

% Buck Mode

idx = find(isBuck);

dutyCycle = dutyCycleBuck;

delay = delayBuck;

q1 = dutyCycle / 100;

q2 = 0;

q3 = 1 - q1;

q4 = 1;

elseif inputVoltage == batteryVoltage

% Battery Voltage Mode

q1 = 1;

q2 = 0;

q3 = 0;

q4 = 0;

% Optionally, you can set dutyCycle and delay for this mode if needed.

else

error('Input voltage is out of the specified range.');

end

end

However, I encountered this error shown below:

[dpb]

Didn't know about the intent to use Coder; you'll have to write the comparisons explicitly to duplicate the functionality.

Or, you could probably rearrange to use interp1

It's not clear what it's supposed to do when voltages aren't identically those specific levels; is it not possible to be anywhere else?

[Danikha Shyken]

I'm not sure I'm following, but like this?

function [q1, q2, q3, q4] = buckBoostController(inputVoltage)

% Constants for duty cycle and delay values

boostVoltages = [0.3, 0.4, 1.2];

dutyCycleBoost = [85.71, 81.82, 60.00];

delayBoost = [51.444, 65.448, 144.000];

dutyCycleBuck = 47.37;

delayBuck = 170.532;

% Define the battery voltage

batteryVoltage = 1.8;

% Check if inputVoltage is in the boostVoltages range

isBoost = any(inputVoltage == boostVoltages);

if isBoost

% Boost Mode

dutyCycle = interp1(boostVoltages, dutyCycleBoost, inputVoltage, 'linear', 'extrap');

delay = interp1(boostVoltages, delayBoost, inputVoltage, 'linear', 'extrap');

q1 = 1;

q2 = dutyCycle / 100;

q3 = 0;

q4 = 1 - q2;

elseif inputVoltage == 2.0

% Buck Mode

dutyCycle = dutyCycleBuck;

delay = delayBuck; % If delay is constant in Buck Mode, you can set it here as needed

q1 = dutyCycle / 100;

q2 = 0;

q3 = 1 - q1;

q4 = 1;

elseif inputVoltage == batteryVoltage

% Battery Voltage Mode

q1 = 1;

q2 = 0;

q3 = 0;

q4 = 0;

% Optionally, you can set dutyCycle and delay for this mode if needed.

else

error('Input voltage is out of the specified range.');

end

end

[dpb]

Please format your code (leftmost icon/button in CODE section) so it can be selected/edited/copied more easily.

"... but like this?"

No, not really. That reverts back to/retains the identical issue of the exact test for equality that is bound to be what is failing -- although you've not told us what, specifically, is the failure you're seeing; we're having to presume from what the code looks like, not from any hard symptomatic information.

The intent with interp1 would be to eliminate the "if" construct entirely and return the proper output voltage based on the input -- but you also didn't answer the question of what's supposed to happen with other input voltages than those exact numbers and what the actual voltages are that can be seen -- and how inputs switch/move from one input level to another--that can't be by instantaneous jumps in a continuous model can it???

[Danikha Shyken]

We already have a functioning automatic input selector, and its output is fed into the buck-boost converter controller as seen in the above figure. However, I think there's an issue with the controller code, particularly in the switching (q1, q2, q3, and q4) because the converter only outputs 0. If the input voltage falls below 0.3V, the battery is the only available source, providing 1.8V. On the other hand, if the input voltage exceeds 2V, the input selector outputs 2V, which is the upper bound of the available source (PZT). If the input voltage is 0.5V, it falls between the range of 0.4V to 1.2V. Since it's closer to 0.4V, the input selector will output 0.4V.

[Danikha Shyken]

I'm hoping you can help me in fixing the controller code.