From 1f69aa31147403f13cb415f340d62791e415e000 Mon Sep 17 00:00:00 2001 From: Alvie Rahman Date: Wed, 15 Nov 2023 12:24:19 +0000 Subject: [PATCH] minor corrects to report, add pwm_on_off.svg --- images/pwm_on_off.svg | 240 ++++++++++++++++++++++++++++++++++++++++++ report.md | 15 +-- 2 files changed, 249 insertions(+), 6 deletions(-) create mode 100644 images/pwm_on_off.svg diff --git a/images/pwm_on_off.svg b/images/pwm_on_off.svg new file mode 100644 index 0000000..1e58396 --- /dev/null +++ b/images/pwm_on_off.svg @@ -0,0 +1,240 @@ + + + +100 % duty cycle75 % duty cycle50 % duty cycle25 % duty cycle10 % duty cycle diff --git a/report.md b/report.md index 8230d1c..cf3a121 100755 --- a/report.md +++ b/report.md @@ -26,6 +26,7 @@ uuid: 864e5249-a02c-4896-b274-a0a76789955c ## Question 2 - 100 % duty cycle PWM is different from all the others as it is not a wave, but just a DC voltage + (the entire region is the ON region, hence it is not underlined in the figures) - Voltage is not zero in the OFF region because the rotational inertia is still spinning the motor, which creates a back EMF, and that is the voltage being read in the OFF region. Back EMF is proportional to the speed of the motor, which is why the voltage in the off region is @@ -37,13 +38,15 @@ uuid: 864e5249-a02c-4896-b274-a0a76789955c ## Question 3 -- The difference between the ON+ and ON- is that the current will go in opposite directions, - resulting in the motor spinning in opposite directions -- The default PWM frequency of pin 13 on the Arduino Mega 2560 is 976.5625 Hz [^1] -- The audible frequency we hear is a ~1000 Hz square wave, which can be seen by the fact the period of - the wave in figure below is roughly 1 millisecond +![H-Bridge at different states](./images/h-bridge.png) - ![PWM waveform at 977 Hz](./images/pwm_frequency.jpg) +- The difference between the ON+ and ON- in the figure above is that the current will go in opposite + directions, resulting in the motor spinning in opposite directions +- The default PWM frequency of pin 13 on the Arduino Mega 2560 is 976.5625 Hz [^1] +- The audible frequency we hear is a ~1000 Hz square wave, which can be seen by the fact the period + of the wave in figure below is roughly 1 millisecond (see figure below) + + ![PWM waveform at 977 Hz](./images/pwm_frequency.jpg){ height=2in } \newpage