This project is used to control the speed of single phase induction motor by employing Luo converter. The Luo converter is used to boost the input voltage. The boosted dc voltage is applied to the single phase inverter. This single phase inverter is converts dc voltage into single phase ac voltage. Single phase induction motor speed depends on the frequency of inverter.
This project is mainly used for renewable energy source like solar, wind etc. The solar converts the sunlight directly into electricity. That voltage range is low, so that low voltage is boosted by using the converter circuits. Converter is used to convert the low voltage dc into high voltage dc. Solar energy is involved in power plants, homes made appliances, ventilation systems, commercial appliances, solar lighting, cars and other remote applications where transmission and distribution is done.
The luo converter has one inductor, one power switch and two diodes. And also has filter for reduce the harmonics of the output voltage. When power switch is turned on inductor gets energized and the voltage is goes to output capacitor through diodes. The capacitor is discharge the voltage across the load. The luo converter power device duty cycle is varied, the motor speed also varying. The luo converter dc voltage is applied to inverter. The inverter is converts the dc voltage into ac voltage. The frequency of luo converter is varied the motor speed also varying.
Block Diagram Explanation
- Pulse generator: - Here we have used PIC microcontroller (PIC 16F877a) to generate PWM signal.
- Driver circuit: It is used to amplify the pulses and provided isolations using opto coupler. It has two functions,
- Bridge Rectifier: It converts AC supply to DC Supply.
- LUO converter: It converts low voltage DC to high voltage DC supply.
- Single phase Inverter: It converts DC supply to single phase AC Supply to drive the single phase induction motor.
Pic Controller Board
The PIC controller is used to generate the PWM pulses for converter and inverter circuit. The PIC 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 is connected to the main power circuit devices. The ac supply is converted into dc by using bridge rectifier. And the dc voltage is boosted by using LUO converter. The boosted dc voltage is applied to inverter circuit and by varying the frequency of the inverter the motor speed also varied.
Circuit Diagram for Luo Converter
Circuit Diagram for Single Phase Inverter
- High efficiency
- Easy to control the speed
- Switching losses are reduced
- Industrial applications
- Pumping system
The speed control of single phase induction motor by employing LUO converter is mainly used to convert the low voltage sources to useful voltage source. The solar voltage produced is low voltage and the LUO converter is used to boost the low voltage and applied the dc voltage to single phase inverter circuit. So that low voltage solar energy is used to control the induction motor speed.
Output Waveform for Luo Converter
Inverter Output Waveform