How to Use Microcontroller for Power Converter Control

To use a microcontroller for power converter control, program it to generate PWM (Pulse Width Modulation) signals that regulate the converter's switches. The microcontroller reads sensor inputs like voltage and current to adjust the PWM duty cycle, maintaining stable output voltage or current.

Syntax

Using a microcontroller for power converter control involves these main parts:

• PWM generation: Create signals to switch power devices on and off.
• Sensor reading: Measure voltage, current, or temperature inputs.
• Control algorithm: Adjust PWM based on sensor feedback.
• Output pins: Connect to power converter switches (e.g., MOSFET gates).

C++

#define PWM_PIN 9
#define SENSOR_PIN A0

void setup() {
  // Initialize PWM pin as output
  pinMode(PWM_PIN, OUTPUT);
  // Initialize ADC for sensor input
  analogReference(DEFAULT);
}

void loop() {
  int sensorValue = analogRead(SENSOR_PIN);  // Read sensor
  int dutyCycle = map(sensorValue, 0, 1023, 0, 255);  // Convert to PWM duty
  analogWrite(PWM_PIN, dutyCycle);  // Output PWM
  delay(10);  // Small delay for stability
}

Example

This example shows a simple microcontroller program that reads a voltage sensor and adjusts the PWM output to control a buck converter's output voltage.

C++

#define PWM_PIN 9
#define SENSOR_PIN A0

void setup() {
  pinMode(PWM_PIN, OUTPUT);
  analogReference(DEFAULT);
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(SENSOR_PIN);  // Read voltage sensor
  int dutyCycle = map(sensorValue, 0, 1023, 0, 255);  // Map sensor to PWM
  analogWrite(PWM_PIN, dutyCycle);  // Set PWM duty cycle
  Serial.print("Sensor: ");
  Serial.print(sensorValue);
  Serial.print(" -> PWM duty: ");
  Serial.println(dutyCycle);
  delay(100);
}

Output

Sensor: 512 -> PWM duty: 127
Sensor: 520 -> PWM duty: 129
Sensor: 510 -> PWM duty: 126
...

Common Pitfalls

Common mistakes when using microcontrollers for power converter control include:

• Not filtering sensor signals, causing noisy readings and unstable control.
• Using incorrect PWM frequency that does not match the power converter's requirements.
• Failing to implement safety limits, risking damage to components.
• Ignoring timing constraints, leading to delayed or jittery control signals.

Always use proper filtering, select suitable PWM frequency, and implement feedback control carefully.

C++

/* Wrong way: No filtering, direct sensor read */
int sensorValue = analogRead(SENSOR_PIN);

/* Right way: Use averaging filter for stable reading */
int readFilteredSensor() {
  int sum = 0;
  for (int i = 0; i < 10; i++) {
    sum += analogRead(SENSOR_PIN);
    delay(1);
  }
  return sum / 10;
}

Quick Reference

Tips for microcontroller power converter control:

• Use PWM outputs to drive power switches.
• Read sensors with ADC and filter readings.
• Implement feedback loops to adjust PWM duty cycle.
• Choose PWM frequency matching converter design (typically tens to hundreds of kHz).
• Include safety checks to prevent overcurrent or overheating.

Key Takeaways

Generate PWM signals from the microcontroller to control power converter switches.

Use sensor inputs and feedback loops to adjust PWM duty cycle for stable output.

Filter sensor readings to avoid noise and unstable control.

Select PWM frequency suitable for the specific power converter design.

Implement safety limits to protect hardware from damage.