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INTRODUCTION

Power electronics is an enabling technology, providing the needed interface between the

electrical source, and the electrical load, Fig. 1.

Controller

Power Electronic interface

Converter

Source Load

Fig. 1 Power electronic interface between the source and the

load

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INTRODUCTION

The task of Power Electronics is to process and control the flow of electric power by supplying

voltage s and currents in a form that is optimally

suited for user loads.

To convert electrical energy from one form to another, i.e. from the source to load with:

highest efficiency,

highest availability

highest reliability

lowest cost,

smallest size

least weight.

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INTRODUCTION

Fig. 2: Block diagram of a power electronic system

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Fig. 3: Interdisciplinary nature of power electronics

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Applications of Power Electronics

Industrial applications

Drives

Pumps, Compressors, Blowers and fans,

Machine tools, Elevators, Cranes, Conveyors,

Hoists.

Approx. 2/3 of the generated electric energy in

industrial countries is consumed by the various

drives.

A large portion of these drives is ac drive.

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INTRODUCTION

The basic parts of the drives are the power supplies and the electromechanical power

converter (electrical machine.) A functional block

diagram of an ac electric drive is seen in the

Figure below.

Figure 4. Block diagram of an ac motor drive

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INTRODUCTION

Electric heat generation

Arc furnace, Resistive heating , Induction heating (high frequency current in a coil)

HV transmission

The technical and economical reason for application is that there are certain areas where

high voltage transmission is needed between two

systems with different frequencies (e.g.: Japan,

where a 50Hz system is connected to a 60Hz

system) or the HV transmission is more

economical as it has higher efficiency.

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INTRODUCTION

Used for transmitting high electric power to large distances, through DC line (parallel losses). The

system consists of an AC/DC and a DC/AC

converter as shown in the figure below.

Power level of such a system is 200-600MW.

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INTRODUCTION

Power Supplies

Important parameters:

Power density [W/in3,W/cm3]

present limits are around 30-50W/in3.

Tolerance

Ripple - input reflected ripple (current)

- output ripple (voltage), EMC/EMI -

noise levels [dB]

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INTRODUCTION

UPS Systems (Uninterruptable Power Supply) are

used where high availability, and/or reliability of the

power supply is required.

Application:

Computers: process control, banks, servers

Energy transmission and distribution

Communication

Hospitals

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INTRODUCTION

Robots where motors, actuators are needed

Induction Heating melting, annealing, heat treatment

Electric Arc Welding Power Sources

Residential applications

Alarms

Refrigeration: temperature control (bang-bang

control, on-off control)

Space heating

Air conditioning

Washing machines drives, control- program storage, electric heating

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INTRODUCTION

Cooking: microwave ovens, induction heating

Lighting

Electronics (PCs, Home Entertainment)

Electric Door Openers

Hand Power Tools

Commercial Applications

Heating,

Ventilating, Air Conditioning (Fan drives)

Central Air Conditioning

Computers and Office equipment

UPS

Elevators

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INTRODUCTION

Lighting electric discharge tubes

CFL (Compact Fluorescent Lamp with integrated PE

device)

Transportation

Traction Control

Battery Chargers (onboard chargers)

Electric Locomotives (Super Conducting material,

Magnetic Levitation vehicle : 500 km/h)

Trams, Trolley Buses

Subways

Automotive electronics including engine control

Electric cars (onboard chargers, regenerative braking)

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INTRODUCTION

Utility systems

High voltage DC transmission (HVDC)

Static var generation (to compensate reactive power

in the system to reduce power loss)

Nuclear reactor control rod

Supplemental energy storage systems (magnetic

energy storage with super conducting coil)

Remote control by audio frequency signals

Generator exciters

Induced-draft fans and pumps

Active filters, for filtering higher harmonic components

time domain control

frequency domain control

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INTRODUCTION

Aerospace

Space shuttle power supply system

Satellite power systems, solar power supplies

Aircraft power supplies: they are using 400Hz

network system. Airports are also using 400Hz

networks.

Telecommunications

Battery chargers

Power Supplies (DC and UPS)

HF inverter radio transmitter for AM service

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INTRODUCTION

Military

Gun elevation

Tracking systems

High power density power supplies

Computers

Power Supplies (SMPS, e.g. 3.3V, 500A)

Floppy and hard disc drives

Driving circuits for printer heads

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INTRODUCTION

Medical

Artificial internal organs

Artificial heart systems

HV power supplies for X-ray machines

Power supplies for diagnostic equipment (magnetic

resonance, computer tomography, ultrasonic

diagnostics, ECG)

HF heating (Short wave)

Pace makers

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Static applications Example

involves non-rotating or moving mechanical

components.

Examples:

DC Power supply, Un-interruptible power supply, Power generation and transmission

(HVDC), Electroplating, Welding, Heating,

Cooling, Electronic ballast

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Drive applications Example

intimately contains moving or rotating

components such as motors.

Examples:

Electric trains, Electric vehicles, Air conditioning System, Pumps, Compressor,

Conveyer Belt (Factory automation).

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Power Conversion concept

Supply from TNB: 50Hz, 240V RMS, (340V peak).

Customer need DC voltage for welding purpose,

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We can use simple half-wave rectifier. A fixed DC voltage is now obtained. This is a simple PE

system.

Average output voltage :

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How if customer wants variable DC voltage? More complex circuit using SCR is required.

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INTRODUCTION

Average output voltage :

By controlling the firing angle ,the output DC voltage (after conversion) can be varied.

Obviously this needs a complicated electronic system to set the firing current pulses for the SCR

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General Types Power Electronics Converters

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Power Electronics Converters

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Power Electronics Converters

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Power Electronics Converters

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More detailed types of Converter Systems

1. AC voltage controllers: Fixed voltage AC to variable

voltage AC

2. Rectifiers: (uncontrolled) Fixed voltage AC to fixed

voltage DC

3. Rectifiers: (controlled) Fixed voltage AC to variable

voltage DC

4. DC/DC converters Fixed voltage DC to variable DC

(Choppers):

Reduction: Buck Converter

Increase: Boost Converter

Reduce/inc.: Buck-Boost Converter

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More detailed types of Converter Systems

5. Inverters (uncontrolled.): Fixed DC to fixed AC

voltage

6. Inverters (controlled): Fixed DC to variable AC

voltage (Square/trapezoidal/sine wave output)

7. Cycloconverters: Fixed frequency and voltage AC to

variable frequency (and voltage)AC output

(frequency reduction)

8. Matrix Converters Fixed frequency and voltage AC

to variable frequency (and voltage) AC output

(frequency increase/reduction, changing the number

of phases)

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Applications of Power Converters

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