Vp Electronics Winter Training Presentation

INVERTERSREPORT BY: URVASHI

KHANDELWAL

CONTENT INVERTER Goals of a well designed inverter Application Types of power converter Introduction to inverters Properties of an ideal inverter Block diagram of an inverter Pulse Width Modulation Inverter operation

INVERTER

Goals of a well designed inverter

Applications

Types of power converters

Introduction TO INVERTERS

• It is a type of power converter that changes direct current (DC) to alternating current(AC)

• Inverters take dc from a battery (etc) and convert it electronically to ac power.

An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate switching, and control circuits. The inverter converts the DC electricity from sources such as batteries, solar panels or fuel cells to AC electricity.

Properties of an ideal inverter

• Dc input is free of ripple

• Ac output is sinusoidal or has a controllable wave shape

Block diagram of Inverter OR what does an inverter do

PWM(pulse width modulation)• It is a modulation technique used to encode a message into a pulsing signal.

• The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on and power is being transferred to the load, there is almost no voltage drop across the switch. Power loss, being the product of voltage and current, is thus in both cases close to zero. PWM also works well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle.

• The term duty cycle describes the proportion of 'on' time to the regular interval or 'period' of time; a low duty cycle corresponds to low power, because the power is off for most of the time. Duty cycle is expressed in percent, 100% being fully on.

Inverter OPERATION

• Inverters are classified by their ac output waveform.

1.Square wave2.Modified sine wave3.True sine wave

Inverter operation

Sine wave Inverter

• Good accuracy• Less power loss• Complex design• More expensive

• Pure sine waveThe electrical circuit of a pure sine wave inverter is far more complex than a square wave or modified sine wave inverter. Another way to obtain a sine output is to obtain a square wave output from a square wave inverter and then modify this output to achieve a pure sine wave. A pure sine wave inverter has several advantages.

• More efficiency, hence consumes less power.

• They can be adjusted according to your personal power requirements, since several types are available with different power outputs.

• Modified sine waveA Modified sine wave shows some pauses before the phase shifting of the wave, i.e. unlike a square it does not shift its phase abruptly from positive to negative, or unlike a sine wave, does not make a smooth transition from positive to negative, but takes brief pauses and then shifts its phase.

Modified sine wave application• electric blankets• computers• motor-driven appliances• toasters• coffee makers• most stereos• ink jet printers• refrigerators• TVs• microwave ovens, etc.

Pure sine wave application• digital clocks• some battery chargers• most light dimmer• some battery operated gadgets that recharge in an AC receptacle• some chargers for hand tools

Square wave inverter

• Cheap• Very poor regulation• Produce large amounts of RFI• Large amounts of harmonics• Very rough AC• Often used for small appliances e.g. fluro lights Very few but the very cheapest inverters any more are square wave. A square wave inverter will run simple things like tools with universal motors with no

problem - but not much else. These are seldom seen any more except in small, very cheap or very old inverters.

Application of square wave inverter

•  low cost AC motor drives like UPS• induction heating units• electronic ballasts• fluorescent lamps

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