AC Variable Frequency Drives (Professional)

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Hours: 16
Certification : Yes
Access : 3 Years

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 Badgr,  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

VFDs, VSDs, ASDs, VVVF Converters, Inverters
AC Motors
An ac induction motor
Speed Control of ac induction motors
Power, Speed and 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
Possibility of replacing DC drives with AC VFDs
Disadvantages of VFDs
Cannot be used with all motors
Distance limitations
Industrial applications of VFDs


Module 2: Inside a VFD

Inside a VFD
Overall design
Rectifier Block
DC Link block
Inverter block
Controller block
VFD parts & VFD components
VFD Components
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
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
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

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
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
Safety Aspects
Summary and Conclusion

Self Assessment Test-VFDs

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.