• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

New Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos 

You are here: Home / Motor Controller / Single Phase Variable Frequency Drive VFD Circuit

Single Phase Variable Frequency Drive VFD Circuit

Last Updated on November 2, 2022 by Swagatam 303 Comments

The post discusses a single phase variable frequency drive circuit or a VFD circuit for controlling AC motor sped without affecting their operational specifications.

What is a VFD

Motors and other similar inductive loads specifically do not "like" operating with frequencies that might be not within their manufacturing specs, and tend to become a lot inefficient if forced to under such abnormal conditions.

For example a motor specified for operating with 60Hz may not be recommended to work with frequencies of 50 Hz or other ranges.

Doing so can produce undesirable results such as heating up of the motor, lower or higher than the required speeds and abnormally high consumption making things very inefficient and lower life degradation of the connected device.

However operating motors under different input frequency conditions often becomes a compulsion and under such situations a VFD or a variable frequency Drive circuit can become very handy.

A VFD is a device which allows the user to control the speed of an AC motor by adjusting the frequency and voltage of the input supply as per the motor specifications.

This also means that a VFD allows us to operate any AC motor through any available grid AC supply regardless of its voltage and frequency specs, by suitably customizing the VFD frequency and voltage as per the motor specifications.

This is normally done using the given control in the form of a variable knob scaled with different frequency calibration.

Making a VFD at home may sound to be a difficult proposition, however a look at  the design suggested below shows that after all it's not so difficult to build this very useful device (designed by me).

Circuit Operation

The circuit can be fundamentally divided into two stages: The half brige driver stage and the PWM logic generator stage.

The half bridge driver stage uses the half bridge driver IC IR2110 which single handedly takes care of the high voltage motor drive stage incorporating two high side and low side mosfets respectively.

The driver IC thus forms the heart of the circuit yet require just a few components for implementing this crucial function.

The above IC however would need a high logic and a low logic in frequencies for driving the connected load at the desired specific frequency.

These hi and lo input logic signals become the operating data for the driver IC and must include signals for determine the specified frequency as well as PWMs in phase with the mains AC.

The above info are created by another stage comprising a couple of 555 ICs and a decade counter. IC 4017.

The two 555 ICs are responsible for generating the modified sine wave PWMs corresponding to the full wave AC sample derived from a stepped down bridge rectifier output.

The IC4017 functions as a totem pole output logic generator whose alternating frequency rate becomes the MAIN frequency determine  parameter of the circuit.

This determining frequency is plucked from pin#3 of IC1which also feeds the IC2 triggering pin out and for creating the modified PWMs at pin#3 of IC2.

The modified sine wave PWMs are scanned at the outputs of the 4017 IC before feeding the IR2110 in order to superimpose exact "print" of the modified PWMs at the output of the half bridge driver and ultimately for the motor which is being operated.

Cx and the 180k pot values should be appropriately selected or adjusted in order to provide the correct specified frequency for the motor.

The high voltage at the drain of the high side mosfet must also be calculated appropriately and derived by rectifying the available mains voltage AC after suitably stepping it up or stepping it down as per the motor specs.

The above settings will determine the correct volts per Hertz (V/Hz) for the particular motor.

The supply voltage for both the stages can be made into a common line, same for the ground connection.

TR1 is a stepped down 0-12V/100mA transformer which provides the circuits with the required operating supply voltages.

The PWM Controller Circuit

caution electricity can be dangerous

You will have to integrate the outputs from the IC 4017 from the above diagram to the HIN and LIN inputs of the following diagram, appropriately. Also, connect the indicated 1N4148 diodes in the above diagram with the low side MOSFET gates as shown in the below diagram.

The Full Bridge Motor Driver

Update:

The above discussed simple single VFD design can be further simplified and improved by using a self oscillatory full bridge IC IRS2453, as shown below:

Here the IC 4017 is completely eliminated since the ful bridge driver is equipped with its own oscillator stage, and therefore no external triggering is required for this IC.

Being a full bridge design the output control to the motor has a full range of zero to maximum speed adjustment.

The pot at pin#5 of IC 2 can be used for controlling the speed and the torque of the motor through PWM method.

For V/Hz speed control the Rt/Ct associated with the IRS2453 and R1 associated with IC1 can be respectively tweaked (manually) for getting appropriate results.

Simplifying Even More

Warning: The 310 V is mistakenly shown. The supply to the source terminals of the P-channel MOSFETs cannot be higher than their gate voltage. Since the 4017 IC can supply a maximum gate voltage of 15 V, the 310 V must be replaced with 15 V DC, otherwise the MOSFETs will burn. If you wish to use 310 V then the entire MOSFET configuration has to be replaced with a bootstrapping type configuration.

If you find the full bridge section overwhelming, you can replace it with a P, N-MOSFET based full bridge circuit as shown below. This variable frequency driver uses the same concept except the full-bridge driver section which employs P-channel MOSFETs at the high side and N-channel MOSFETS on the low side.

Although the configuration may look inefficient due to the involvement of P-channel MOSFETs (due to their high RDSon rating), the use of many parallel P-MOSFETs might look like an effective approach for solving the low RDSon issue.

Here 3 MOSFETs are used in parallel for the P-channel devices to ensure minimized heating of the devices, on par with the N-channel counterparts.

You'll also like:

  • 1.  2 Simple Bidirectional Motor Controller Circuits Explored
  • 2.  Making a Flynn Motor
  • 3.  L298N DC Motor Driver Module Explained
  • 4.  Treadmill Motor Speed Controller Circuit
  • 5.  High Voltage DC Motor Speed Regulator Circuit
  • 6.  RPM Controller Circuit for Diesel Generators

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

New Posts

  • Sound Activated Remote Control Circuit
  • High Voltage DC Motor Speed Regulator Circuit
  • High Efficiency Solar Charger Circuits using Switching Regulators
  • Mobile Signal Vibrator Circuit
  • AC 220V Over Current Monitor and Cut OFF Circuit

Have Questions? Please Comment below to Solve your Queries! Comments must be Related to the above Topic!!

Subscribe
Notify of
303 Comments
Newest
Oldest
Inline Feedbacks
View all comments


Primary Sidebar

Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (26)
  • 555 IC Circuits (99)
  • 741 IC Circuits (20)
  • Arduino Engineering Projects (83)
  • Audio and Amplifier Projects (118)
  • Battery Chargers (83)
  • Car and Motorcycle (96)
  • Datasheets (77)
  • Decorative Lighting (Diwali, Christmas) (33)
  • Electronic Components (101)
  • Electronic Devices and Circuit Theory (36)
  • Electronics Tutorial (120)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (14)
  • GSM Projects (9)
  • Health Related (20)
  • Heater Controllers (30)
  • Home Electrical Circuits (106)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LED and Light Effect (95)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (67)
  • Mini Projects (152)
  • Motor Controller (68)
  • MPPT (7)
  • Oscillator Circuits (25)
  • PIR (Passive Infrared) (8)
  • Power Electronics (35)
  • Power Supply Circuits (81)
  • Radio Circuits (10)
  • Remote Control (49)
  • Security and Alarm (64)
  • Sensors and Detectors (127)
  • SG3525 IC (5)
  • Simple Circuits (75)
  • SMPS (29)
  • Solar Controllers (62)
  • Timer and Delay Relay (54)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (41)
  • Ultrasonic Projects (16)
  • Water Level Controller (45)

Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2023 · Swagatam Innovations

wpDiscuz