Pulse width modulation

PWM (pulse width modulation) is a technique for generating an analog signal by a digital control. It involves generating a digital signal at a specific frequency that alternates between the two states low and high. By changing the ratio between the duration of the signal in the two states, the average signal can be adjusted, which is an effective method for controlling electronic devices.

The ratio is called the duty cycle and can be controlled by changing the duty cycle and the period of the signal generation. The function setDutyCycle() is a method of the class MPPTController and is used to set the duty cycle of the mosfet in a percentage for the boost controller. The duty input is interpreted as a percentage of the duty cycle time, where 100% means full duty cycle time and 0% means full inhibit time.

To set the duty cycle as a 16-bit integer for PWM control, the entered percentage is first subtracted from 100% to get the lockout time percentage. This value is then multiplied by 65536 and the result rounded to the nearest integer to obtain the duty cycle as a 16-bit value. Finally, the PWM dutycycle is set to the calculated value using the duty_u16 method().

def setDutyCycle(self, duty):
    '''Set mosfet dutycycle for boost converter'''
    self.duty = int(((100 - duty) / 100) * 65536)
    self.pwm.duty_u16(self.duty)