DEPARTMENT OF ELECTRICAL POWER ENGINEERING

COLLEGE OF ENGINEERING

POWER ELECTRONICS

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Summary - Inverters

TOPICS COVERED:

DC TO DC CONVERTER

•  Introduction

Buck (Step Down) Converter

•  Assumptions Made for Analysis of the Buck Converter

•  *Circuit Operation Switching Modes

•  Output Voltage Average

•  The Inductor Current Ripple

•  The Load and the Capacitor Current

•  Continuous Conduction Condition

•  The Capacitor Voltage Ripple

 

Boost (Step Up) Converter

•  Assumptions Made for Analysis of the Boost Converter

•  *Circuit Operation Switching Modes

•  Output Voltage Average

•  The Inductor Current Ripple

•  The Inductor Current

•  Continuous Conduction Condition

•  The Diode and Capacitor Currents

•  The Capacitor Voltage Ripple

Designing DC-DC Converters

•  Converter Design Consideration

PULSE WIDTH MODULATED INVERTERS

•Introduction

•Inverter Types

• Performance Parameters

Single Phase Inverter

• Single Phase Half Bridge Inverter

• Single Phase Full Bridge Inverter

• Methods of Controlling Single Phase Inverter

• Pulse-Width Modulation (PWM) Control Strategy

•Sinusoidal Pulse Width Modulation (SPWM)

Three Phase Inverter

• Line-to-line Voltage Waveform

• Line-to-neutral Voltages

• Output Currents

• Voltage Control of Three Phase Inverters

Inverters

  1. The full bridge and half bridge converters can be used to produce an ac output from a dc input.
  2. A simple switching scheme produces a square wave voltage output, which has a Fourier series that contains the oldd harmonic frequencies of amplitudes: Vn = 4Vdc/ (n )
  3. Amplitude and harmonic control can be implemented by allowing a zero-voltage interval of angle at each end of a pulse, resulting in Fourier coefficients:
  4. Vn = (4Vdc/ n) (cos(n ))

  5. Pulse width modulation (PWM) provides amplitude control of the fundamental output frequency. Although the harmonics have large amplitudes, they occur at high frequencies and are filtered easily.
  6. The six step inverter is the basic switching scheme for producing a three phase ac output from a dc source.
  7. A PWM switching scheme can be used with a three phase inverter to reduce THD of the load current with modest filtering.
  8. The circuit of three phase inverter is applied in speed control of induction motors by varying output frequency.
  • Control strategies for converting dc to ac are:

Single Phase

  1. Square wave inverter
  2. Amplitude and harmonic control
  3. PWM bipolar switching
  4. PWM unipolar switching

Three Phase

  1. Six step inverter
  2. PWM three phase inverter

 

 

Summarized formula:

Summarized formula for inverter in pdf file

 

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