In last article, I have posted a project on three phase sine wave inverter using pic microcontroller. In this article, I will talk about three phase variable frequency SPWM for VFD using pic microcontroller. three phase variable frequency SPWM is used to generate variable frequency for three phase induction motor. This is also used for variable frequency drive for three phase induction motor. In next article, I will post a complete project of three phase variable frequency drive using pic microcontroller. This tutorial is a simulation and demonstration of three phase variable frequency SPWM using pic microcontroller. So now lets start with basic introduction of this project. you may also like to check other power electronics projects.
In this project, PIC18F452 microcontroller is used to generate variable sinusoidal pulse width modulation signals. Variable frequency sinusoidal pulse width modulation signals are 120 degree out of phase with each other. Because, you know in case of three phase power, all three phases must be 120 out of phase with each other. For generation of SPWM signals, I have used a look up table with pre calculated values of duty cycle for pulse width modulation. These pre-calculated duty cycle values are used to generate sinusoidal pulse width modulation. Because value of duty cycle increases from low value to high value. Maximum duty cycle will be at the peak of sine wave and minimum duty cycle will be at the zero crossing. If you don’t know how to generate SPWM, you can check this article:
- SPWM generation using pic16f877a microcontroller
- SPWM generation using Dspic microcontroller
- SVPWM using pic microcontroller
Variable resistor is used to increase or decrease the frequency of SPWM signals. Variable resistor is connected with analog channel of pic18f452 microcontroller. Six signals coming out of pic microcontroller will be fed to three phase H bridge to get three phase sine wave with variable frequency. you can check our article on how to design H bridge using MOSFET driver IR2110.
- Picture below shows three SPWM signals and all three are 120 degree out of phase with each other.
- Output with filters pure sine wave
you can check this complete simulation to check more working of this three phase variable frequency SPWM for VFD using pic microcontroller.
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how can i get the codes!!!
Dear sir welcome I’m interested vfd drive circuit projects 15 KW
Full details and technical and support.
Please can you send me Microcontroller code for this project via mail
Hi Sir!!! I will like to have théecode off this vfd spwm doing by dspic… Thauk Your in advance
hi, I have pic18f452 please help me codes so that I can make a pure sinewave inverter
A variable-frequency drive or adjustable-frequency drive, variable-voltage/variable-frequency drive, variable speed drive, AC drive, microdrive, or inverter drive is a type of motor drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.
How does VFD Communicate with PLC?
Dear sir welcome 😊.
I’m interested vfd microcontroller project.
Your technical and cooperation support.
Thank you
I will get a kick out of the chance to have théecode off this VFD SPWM doing by dspic.
but you are generating pulses both high side and low side gate pulses in same output pwm pin how will you divide low side pulses and high side pulses seperately and how will you give that signals to half bridge configuration if you connected not gate of the generated spwm signal it’s only inverting the received pulses can you explain me how can you sapereted high side gate signals and low side gate signals of the igbt gate???????