This project can be used to control the three phase ac motor by using raspberry pi controller. This AC motor control has three phase inverter circuit. The raspberry pi controller is used to generate the PWM pulses. Inverter is widely used in industrial application such as for DC power source utilization, electric motor speed control and for generating an AC source from a DC source. The power MOSFET devices frequency is varied by using raspberry pi controller. And also varying the speed of the motor.
This AC motor speed control is widely used in industrial applications. In normal microcontroller has ability to generate high frequency switching with low cost. But this raspberry pi controller has new feature blocks in order for designing the controller. So understand the concept of controller in power converters without needs to develop any cross coding algorithm for the switching signals of the converters.
The AC drive system consists of a supply unit, rectification block, gate driver unit, inverter block and the load. The supply is given from 230V, IΦ. The step down transformer of (230V/100V) is used to step down the supply voltage to 100 V AC. Output of the transformer is given to the bridge rectifier which coverts it into 100V DC. 100V dc voltage is fed as input to the three phase inverter. A Raspberry PI is programmed to give PWM pulses to the three phase inverter. The pulses are varied using a key function. The PWM pulses are varied by using key function. The three phase inverter output waveform is shown in the below.
Block Diagram Explanation
- Pulse generator: - Here we have used Raspberry PI controller to make a switching signal.
- Driver circuit: -It can be used to amplify the pulses and provided isolations by using opto coupler. It has two functions,
- Bridge Rectifier: It converts AC to DC Supply.
- Three Phase Inverter: It converts DC to Three Phase AC Supply.
Raspberry Pi Controller Board
The raspberry pi controller is used to generate the PWM pulses for converter and inverter circuit. The raspberry pi controller pulses are given to the driver circuit as input. Driver board is mainly used to isolate and amplify the input signals from the controller. The amplified driver output will be connected to the main power circuit devices. And the devices are turned on by using the PWM pulses. The power transformer is directly connected to the bridge rectifier. The bridge rectifier converts the ac voltage into dc voltage. Dc voltage is converted into three phase ac voltage by using three phase inverter circuit. The three phase inverter output waveform is shown in below.
Circuit Diagram for Three Phase Inverter
- High efficiency
- Easy to control
- Simple construction
- Industrial applications
- Voltage control applications
Thus the three phase AC motor control using Raspberry PI is gives an energy efficient and environment friendly solution. The Raspberry PI pulse will be given to the three phase inverter, so the switching speed will be controlled by using pulse width modulation (PWM). The speed of the motor will be varied by varying the PWM signals.
Three Phase Inverter Output
Three Phase Inverter Pattern