AC Variable Frequency Drives (Standard )

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Hours: 10
Certification : Yes
Access : 1 Year

This AC Variable Frequency Drives e-learning course covers all aspects of VFDs that are used in industry.

This unique course is a mix of text, animations & simulations , self assessment test to make it a unique learning experience. You can earn a Certificate of Competency from Abhisam & an electronic badge via Credly,  after taking the course and passing the associated exam.

Variable Frequency Drive

These are more popular known by their acronym, VFD. These devices are growing in importance every day. In earlier years they used to be mainly found only in manufacturing industries but today they are present everywhere including commercial buildings, warehouses, airports and more. The reason is simple. They are the best thing that ever happened to the ac induction motor, which is the workhorse of our economy today. These drives are also known as Inverter Drives or Frequency Inverters and can now control these motors in a variety of ways, which were not at all possible earlier. In old electrical engineering textbooks, you can find ac induction motors described as a “constant speed machine”. But with the advent of this new technology, we  can now adjust speed as well as other parameters of these motors.

Why an e-learning course on VFDs?

Abhisam is one of the pioneers of promoting self paced e-learning courses for engineering and technical professionals all over the world. There were demands from many customers to have an easy to understand course with animations, simulations, photos and videos on Variable Frequency Drives so that they could have a vendor neutral, unbiased course that covered all aspects of this technology, but was not a boring power point presentation or a dull talk by a guy standing in front of a whiteboard.

The result is this course. Here is what it contains:

Module 1: Basic Concepts

  • Introduction
  • VFDs, VSDs, ASDs, VVVF Converters, Inverters
  • AC Motors
  • An ac induction motor
  • Speed Control of ac induction motors
  • Power, Speed and Torque
  • Torque
  • Locked Rotor Torque
  • Motor characteristics and types
  • Design A motor
  • Design B motor
  • Design C motor
  • Design D motor
  • Design E motor
  • Which type is best for my application?
  • Load torque characteristics for different kind of loads
  • Classification of loads
  • Constant Torque loads
  • Variable Torque loads
  • Constant Power loads
  • Four Quadrant Operation
  • Overview of AC motor controls
  • DOL starter (Direct On Line starter)/Across the line starter
  • Star (Wye) and Delta connections
  • Control with a VFD
  • Speed Regulation
  • Better Power Factor
  • Soft Starting
  • Flexibility in input power
  • Precision Controls for torque and speed
  • Energy Saving
  • Replacement of control valves in process plants
  • Built in PID controls
  • Communication
  • Possibility of replacing DC drives with AC VFDs
  • Disadvantages of VFDs
  • Harmonics
  • Cannot be used with all motors
  • Distance limitations
  • Noise
  • Industrial applications of VFDs

Module 2: Inside a VFD

  • Introduction
  • Inside a VFD
  • Overall design
  • Rectifier Block
  • DC Link block
  • Inverter block
  • Controller block
  • VFD parts & VFD components
  • VFD Components
  • Diode
  • Diode Curve
  • Switching frequency of diodes
  • Rectifier Circuits
  • Half wave rectifier
  • Full wave rectifier (Bridge rectifier)
  • Three phase bridge rectifiers
  • Thyristors (Silicon Controlled Rectifiers-SCRs)
  • Firing angle
  • Three phase rectifier using thyristors
  • DC link block
  • Soft Charge Circuit
  • Inverter Block
  • Transistor (BJT)
  • Working model of a transistor
  • Transistor as an amplifier
  • Transistor as a switch
  • IGBT
  • Pulse Width Modulation
  • How does Pulse Width Modulation work?
  • Changing the amplitude of the output
  • sinusoidal waveform
  • Changing the frequency of the output
  • sinusoidal waveform
  • Noise effects of PWM inverters

Module 3: VFD Functions

  • Starting/Stopping of the motor
  • Acceleration/Deceleration
  • Ramping
  • Speed Limits
  • Speed Changing
    a) Using the digital inputs
    b) Using a potentiometer
    c) Using the analog input signal
    d) Using Digital Communication
  • Forward/Reverse operation
  • Motor Thermal Overload Protection
  • Slip Compensation
  • Control schemes in VFDs
  • Open Loop controls in VFDs
  • Closed loop control with VFDs
  • V/f Control
  • Vector Control
  • What is the “vector” in vector control?
  • Sensorless vector control
  • Flux Vector control (Closed loop)
  • Shaft encoders
  • Absolute encoders
  • Incremental encoders
  • Difference between absolute encoder and incremental encoder
  • Closed Loop Flux Vector Control
  • Field Oriented Control (FOC)
  • Comparison between V/f drives and Vector Control drives.
  • PID Control
  • Anti-windmill protection and Flying Start
  • Anti-windmill protection
  • Flying Start-Catching up with the motor at power on
  • Skip Frequencies
  • Torque Control
  • Direct Torque Control
  • How does DTC work?
  • Advantages of DTC
  • Disadvantages of DTC
  • Motoring and regeneration
  • Braking Resistor
  • Dynamic Braking
  • Line regenerative braking
  • DC injection braking
  • Motor Overflux braking

Module 4: Energy Savings using VFDs

  • Types of Loads
  • Pumps, Fans and Blowers
  • Traditional flow control
  • Control of Centrifugal Pumps
  • Affinity Laws of Centrifugal Pumps
  • Centrifugal Pump basics
  • Pump Characteristic Curve
  • System Curve
  • Energy savings with fans and blowers
  • Other energy savings due to VFDs
  • Power Factor improvement
  • Reduction in demand charges
  • Shorter Duty Cycles

Module 5: Specifying, Selecting and Installing a VFD

  • Flowchart
  • Load considerations
  • Evaluate VFD benefits versus traditional motor controls
  • VFD features for maximum benefit
  • Derating of VFDs
  • Temperature Derating
  • Altitude Derating
  • Overload Capacity
  • Harmonics due to VFD installations
  • What are Harmonics?
  • Total Harmonic Distortion
  • Problems due to harmonics
  • What could be the PCC? Says who?
  • Measurement of harmonics
  • Harmonics in PWM type drives
  • Mitigation of harmonics
  • Supply voltage
  • Number of starts
  • Fuse Disconnects
  • Bypass circuit
  • Installation inside a panel or other enclosure
  • Earthing
  • Maximum Cable length from VFD to the motor
  • IGBT switching
  • Standing wave & Reflected wave phenomenon
  • Voltage drop
  • Long cable length solutions
  • Multiple inverters in the same VFD

Module 6: Using VFDs with PLC/ DCS /Control systems

  • VFDs used in a process plant
  • Detailed Implementation of the above
  • Digital Communications
  • Need for digital communications
  • Functions of a typical digital network
  • Profibus
  • Modbus
  • Safety Aspects
  • Summary and Conclusion

Self Assessment Test

After you complete the modules, you can take the self assessment test that enables you to measure your level of understanding of VFDs. It also can be used as a mock test or practice test, to help you pass the final certification exam.

 Free Certification

It is not enough to just learn the technology, you need to show to your employers, bosses and clients (both current and future) that you have understood the subject and are qualified to work on them. For this you need a trusted third party to certify your knowledge.

Luckily, you have Abhisam, one of the most popular e-learning and training companies in the world, to do this for you. Simply take the associated exam that follows this VFD Training Course and you can earn a Certificate of Competency and an electronic badge (issued via Credly, the largest badge issuer on the planet). Abhisam is a verified Credly badge issuer and this fact enables you to easily share your newly achieved digital credential on places online, such as LinkedIn and Facebook. This showcases your achievements to the whole world as well as your connections and is a great way of landing a better job or assignment.

The best part of this is that it is included with the course fee, so there is nothing extra to pay!

Enterprise Versions

We have different versions for individuals and companies or large organizations. If you are a company or similar large organization, then you can buy the Enterprise Version of this course. It allows every learner to have a separate account, to access the course and complete it at his or her own pace. You as an employer or boss, can get a complete record of learner activity on the portal including time spent on every module and test scores. This is an easy way to keep training records if it is mandated by either your internal procedures or by an external agency.

Your learners also earn Professional Development Hours (PDH) for this course.

If you already have a Learning Management System (LMS) in your organization that accepts SCORM or TinCan content, then we can stream this course directly to your LMS, so that your learners can have all their training modules in one place. The pricing for this service is different, please get in touch with us to know more.