Notes
Power electronics
Content of the notes (25)
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Applications
Less than 100W: Small motor drives used in home appliances (washing machine, vacuum cleaners, hand dryers, induction cooking, hood fan) ,Switched-mode power supplies for portable equipment
Less than 10kW: • Power supplies for Laptop/PC, Variable-speed motor drives used in commercial buildings
10kW up to 1MW: • High power motor drive • Traction control • Renewable energy system
More than 1MW: • Utility transmission lines • Grid connected system • Reactive Power Control
Photo Voltaic Systems: Using solar panels, an unregulated dc voltage must be boosted and then converted to AC voltage with standard grid amplitude and frequency
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Wind turbine generator: Wind turbines generate voltage with variable frequency and amplitude due to variable power and speed of wind. A power converter is needed to convert the variable AC voltage to the adjustable one suitable for grid.
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Loss generated by current
Heat increased
Efficiency decreased
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AC to DC conversion
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Power Electronics System Modules
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Input: (AC or DC) voltage or current source and a load, e.g. resistive load.
Cascade Conversion: multiple converters connected in cascade.
Power semiconductor devices: power switches to chop input voltage or current waveform to control the flow of energy.
Control system: open-loop or close-loop system implemented mainly in digital electronics (in some cases we use analog circuits)
Gate drivers: Gating circuit to provide the gate drive signals to support switching devices if the control signals would not be strong enough for switching
Circuit breakers: One or more static switches acting as a circuit breaker to run off the whole system if there is any short circuit.
Sensors: Current, voltage and thermals sensors for overvoltage, overcurrent and over temperature scenarios.
Filters: Input and output filters for immunity and emission control.
High Power and Low Power:
Power diode
Power Metal-oxide Field-Effect Transistor (Power MOSFET)
Insulated-Gate Bipolar Transistor (IGBT)
High Power:
• Silicon-Controlled Rectifier (SCR) or Thyristor
• Power Bipolar Junction Transistor (BJT)
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Thyristor:
Application in high voltage converters due to its characteristic of withstanding high voltage and delivering high current
Used in simple and cheap AC-AC converters
Gate Turn-off Thyristor (GTO) for high power applications.
MOS-Controlled Thyristor (MCT) for high power applications.
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Application of Power Converters
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Power Factor Correction
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P is not time dependent.
When θv = θi , it is a purely resistive load case.
When θv– θi = ±90o, it is a purely reactive load case.
P = 0 means that the circuit absorbs no average power.
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Power diodes
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Thyristor
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Single-phase half-wave rectifiers
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Single-phase full-wave rectifier
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Information
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- Note on Power electronics, created by Rezi Tsulukidze on 07/05/2018.
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- Rezi Tsulukidze
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