Inverters offer speed or torque control of electric motors.
Maybe you have walked past without noticing them or maybe you know exactly how many you have, either way electric motors play an important role in our everyday lives which most of us are unaware of but, they move and run most things we need for business and pleasure.
All these motors consume electricity so need a corresponding amount of energy to provide the torque or speed needed. If the torque or speed is too high or low, mechanical controls are used to control output. A motor’s speed should match exactly what is required by the process, otherwise the result is inefficiency with a lot of wasted materials and energy.
Not knowing how to control motors can mean a lot of energy gets wasted which isn’t good for any business. A way to control these motors, which not only saves energy, but improves productivity and reduces maintenance costs, is to use an inverter.
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2. Inverter
device which supplies variable frequency of power supply on equipment
motor revolution speed can be controlled and it leads to reduce energy
consumption
3. Basic structure of inverter device
Inverter device consists of mainly two parts; converter and inverter
Originally the meaning of “Inverter” is changing DC power source into AC
power source.
In order to make supplied frequency variable, once the AC power source is
changed into DC at Converter part
4. Basic structure of inverter device
Function of Converter
Converter part converts AC power supply into DC thanks to Diode
bridge circuit
Diode: electrical component which allows current go through on one
way
5. Basic structure of inverter device
Function of Inverter
By signal being input on each transistor, current will go through the
motor. This signal input format is different according to the motor (AC
inverter / DC inverter)
7. AC Inverter versus DC Inverter
The inverter that drives an AC motor is called “AC inverter”
the one which drives DC motor is called “DC inverter”
10. AC Inverter versus DC Inverter
Advantage and disadvantage of AC motor
ADVANTAGES
Simple structure
Easy to control
induction current is generated on the cage according to the
rotating magnetic field, so the rotor will be driven accordingly
without detecting rotor position.
11. AC Inverter versus DC Inverter
Advantage and disadvantage of AC motor
DISADVANTAGES
Less efficiency caused by
induction current loss
motor slip
12. AC Inverter versus DC Inverter
Structure of DC motor
rotor is made of permanent magnet
14. AC Inverter versus DC Inverter
Advantage and disadvantage of DC motor
ADVANTAGES
Less loss and better efficiency than AC motor because of
no motor slip
no induced current loss
15. AC Inverter versus DC Inverter
Advantage and disadvantage of AC motor
DISADVANTAGES
Needs enough knowledge to drive
Rotor position needs to be detected anytime to drive it and
stator coil should be energized accordingly to the rotor
position.
16. Evolution from AC Inverter to DC
Converter
Demand for more efficient, less energy consumption
In order to attain better efficiency, it is not enough only to apply (AC)
inverter technology so as to reduce the compressor speed, but also to
reduce energy consumption when In partial load conditions
DC motor has been known as much more efficient motor than AC, and its
efficiency is roughly double compared to AC
DC inverter is a good solution for reducing energy consumption.
17. DC PAM inverter
DC Pulse Amplitude Modulation Inverter
booster circuit is added on the converter part to raise up DC voltage.
19. DC PAM inverter
Importance of PAM Control
To apply more efficient dc motor
motor which have larger number of winding on one slot has better
efficiency because it can generate stronger magnetic field
Disadvantage: cannot accept bigger current because the diameter
of the wire should be thin
Solution: raising input voltage up, making the total input same
without increasing current, and become possible to drive the
compressor at higher torque
20. Vector control DC inverter
cutting-edge technology of the inverter control in order to let the
compressor give the better performance by generating sinusoidal current
wave form
21. Vector control DC inverter
Importance
less compressor starting failure
detect the rotor position correctly, and it lead to improve
compressor starting
Downsizing and high efficiency
High revolution operation on high efficiency (high turn motor)
compressor became possible thanks to the sinusoidal wave form
drive
22. Vector control DC inverter
Importance
to apply more efficient DC motor
detect the rotor position correctly, and it lead to improve
compressor starting
a motor which has a larger number of windings on one slot has
better efficiency because it can generate a stronger magnetic field
there is no non-energized period and it leads to reduce peak
current that can make a more efficient compressor DC motor
Disadvantage: cannot accept bigger because the diameter of the winding
wire
23. Types of Inverter
Modified Sine Wave
In a modified sine wave, the voltage rises and falls abruptly, the phase
angle also changes abruptly and it sits at 0 Volts for some time before
changing its polarity.
A modified sine wave inverter actually has a waveform more like a
square wave, but with an extra step or so
24. Modified Sine Wave Inverter
type of home inverter obtains power from a battery of 12 volts and must be
recharged using a generator or a solar panel
held as the best inverters for homes as they are efficient enough to provide
power to the normal home requirement
electric appliances that involve motor speed controls or timers are not to be
run using these types of home inverters
25. Sine Wave Inverter
A sine wave is what you get from your local utility company and from a
generator
the sine waves they produce are purer.
employed for the power sensitive appliances like refrigerators, televisions, air
conditioners, washing machines
The only drawback is that they are a bit expensive and cannot be afforded by the
common man
26. Advantages
Sine Wave Inverter
a complex design producing the AC wave power output similar to that
you would get from your house power point
support all the complicated, sensitive or medical-electrical equipment
which will fail to run from the poor power output of a modified wave
inverter
worth its cost if you want to support expensive and sensitive electrical
equipment
high quality power output from the pure sine wave inverter will
maintain the unit’s power supply throughout, thus supporting these
appliances
27. Advantages
Sine Wave Inverter
The output wave-form is a sine-wave with very low
harmonic distortion and clean power like utility supplied
electricity
Inductive loads like microwaves and motors run faster,
quieter and cooler
Reduces audible and electrical noise in fans, fluorescent
lights, audio amplifiers, TV, fax and answering machines
Prevents crashes in computers, weird print outs and
glitches in monitors
28. Disadvantages
Modified Sine-wave Inverter
Some examples of devices that may not work properly with modified
sine wave and may also get damaged are given below:
Laser printers, photocopiers, magneto-optical hard drives
The built-in clocks in devices such as clock radios, alarm clocks, coffee makers,
bread-makers, VCR, microwave ovens etc may not keep time correctly
Output voltage control devices like dimmers, ceiling fan / motor speed control
may not work properly (dimming / speed control may not function)
Sewing machines with speed / microprocessor control
29. Modified Sine-wave Inverter
Some examples of devices that may not work properly with modified
sine wave and may also get damaged are given below:
Transformer-less capacitive input powered devices like (i) Razors,
flashlights, night-lights, smoke detectors etc (ii) Re-chargers for
battery packs used in hand power tools.
Devices that use radio frequency signals carried by the AC
distribution wiring
Disadvantages
30. Modified Sine-wave Inverter
Some examples of devices that may not work properly with modified
sine wave and may also get damaged are given below:
Some new furnaces with microprocessor control / Oil burner primary controls
High intensity discharge (HID) lamps like Metal Halide lamps. These may get
damaged. Please check with the manufacturer of these types of devices for
suitability
Some fluorescent lamps / light fixtures that have power factor correction
capacitors. The inverter may shut down indicating overload
Disadvantages
31. Disadvantages
Modified Sine-wave Inverter
Will not function properly in any device that uses a control circuitry
that senses the phase (for voltage / speed control) or instantaneous
zero voltage crossing (for timing control)
modified sine wave is a form of square wave, it is comprised of multiple
sine waves of odd harmonics (multiples) of the fundamental frequency
of the modified sine wave
32. Single-Phase, H-bridge Step-Waveform
Inverters
A H bridge is an electronic circuit that enables a voltage to be applied across a load in
either direction.
used in robotics and other applications to allow DC motors to run forwards and
backwards
35. Advantages of Inverter
Modern drives can control starting currents
maintain precise set speeds, quickly change speeds, control reversing and quickly
stop
potential for energy savings, reduce energy input by 25% to 50% with the simple
addition of an inverter
continuously adjust the speed to maintain a desired situation under varying system
conditions
Multiple machines can be coordinated to have the right number of parts come
together in the right place, and at the right time
Another great advantage is the potential for energy savings
36. disadvantages
Early inverters caused significantly higher temperature rise in
the motor and mismatched could easily burn out the motor
increased motor noise and bearing failure
Burned Endturns
“Typical inverter spike damage to motor windings. Usually in the
first turn near the lamination stack.”
Appliances like microwave ovens, light bulbs, etc. can be run using these types of inverter
(FIRST TWO;) This makes machinery of all types more productive, improves quality and more flexible with quick change over to run different materials with a minimum of downtime