"Power Electronic. In 40 lessons"
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Server:Power Electronic. In 40 Lessons. Another IIT course material from Kharagpur, covers Power Electronic, 3 Phase AC, MOSFET and more.. Great reference for Electrical engineering students or for manufacture engineer.. Module 1 Power Semiconductor Devices. Lesson 1 Power Electronics, objectives: Create an awareness of the general nature of Power electronic equipment; ~ Brief idea about topics of study involved, ~ The key features of the principal Power Electronic Devices; ~ An idea about which device to choose for a particular application. ~ A few issues like base drive and protection of PE devices and equipment common to most varieties.. contents: [ How is Power electronics distinct from linear electronics? ~ Power Semiconductor device - history ~ Power Diodes ~ Silicon Controlled Rectifier (SCR) ~ MOSFET ~ The IGBT ~ The GTO ~ Power Converter Topologies ~ Base / gate drive circuit ~ Protection of Power devices and converters ] Lesson 2 Constructional Features, Operating Principle, Characteristics and Specification of Power Semiconductor Diode, objectives: Draw the spatial distribution of charge density, electric field and electric potential in a step junction p-n diode. ~ Calculate the voltage drop across a forward biased diode for a given forward current and vice-verse. ~ Identify the constructional features that distinguish a power diode from a signal level diode. ~ Differentiate between different reverse voltage ratings found in a Power Diode speciation sheet. ~ Identify the difference between the forward characteristic of a power diode and a signal level diode and explain it. ~ Evaluate the forward current specifications of a diode for a given application. ~ Draw the “Turn On” and “Turn Off” characteristics of a power diode. ~ Define “Forward recovery voltage”, “Reverse recovery current” “Reverse Recovery charge” as applicable to a power diode.. contents: [ Review of Basic p-n Diode Characteristics ~ Construction and Characteristics of Power Diodes ~ Power Diode under Reverse Bias Conditions ~ Power Diode under Forward Bias Condition ~ Switching Characteristics of Power Diodes ] Lesson 3 Power Bipolar Junction Transistor (BJT), objectives: Distinguish between, cut off, active, and saturation region operation of a Bipolar Junction Transistor. ~ Draw the input and output characteristics of a junction transistor and explain their nature. ~ List the salient constructional features of a power BJT and explain their importance. ~ Draw the output characteristics of a Power BJT and explain the applicable operating limits under Forward and Reverse bias conditions. ~ Interpret manufacturer’s data sheet ratings for a Power BJT. ~ Differentiate between the characteristics of an ideal switch and a BJT. ~ Draw and explain the Turn On characteristics of a BJT. ~ Draw and explain the Turn Off characteristics of a BJT. ~ Calculate switching and conduction losses of a Power BJT. ~ Design a BJT base drive circuit.. contents: [ Basic Operating Principle of a Bipolar Junction Transistor ~ Constructional Features of a Power BJT ~ Output i-v characteristics of a Power Transistor ~ Switching characteristics of a Power Transistor ~ Turn On characteristics of a Power Transistor ~ Turn Off Characteristics of a Power Transistor ~ Switching Trajectory and Switching Losses in a Power Transistor ~ Base Drive Design and Power Darlington ] Lesson 4 Thyristors and Triacs, objectives: Explain the operating principle of a thyristor in terms of the “two transistor analogy”. ~ Draw and explain the i-v characteristics of a thyristor. ~ Draw and explain the gate characteristics of a thyristor. ~ Interpret data sheet rating of a thyristor. ~ Draw and explain the switching characteristics of a thyristor. ~ Explain the operating principle of a Triac.. contents: [ Constructional Features of a Thyristor ~ Basic operating principle of a thyristor ~ Steady State Characteristics of a Thyristor ~ Thyristor ratings ~ Switching Characteristics of a Thyristor ~ The Triac ~ Steady State Output Characteristics and Ratings of a Triac ~ Triac Switching and gate trigger circuit ] Lesson 5 Gate Turn Off Thyristor (GTO), objectives: Differentiate between the constructional features of a GTO and a Thyristor. ~ Explain the turn off mechanism of a GTO. ~ Differentiate between the steady state output and gate characteristics of a GTO and a thyristor. ~ Draw and explain the switching characteristics of a GTO. ~ Draw the block diagram of a GTO gate drive unit and explain the functions of different blocks. ~ Interpret the manufacturer’s data sheet of a GTO.. contents: [ Constructional Features of a GTO ~ Operating principle of a GTO ~ Steady state and dynamic characteristics of a GTO ~ Dynamic characteristics of a GTO ~ GTO gate drive circuit ~ GTO Ratings ~ Specifications related to the switching performance ] Lesson 6 Metal Oxide Semiconductor Field Effect Transistor (MOSFET), objectives: Differentiate between the conduction mechanism of a MOSFET and a BJT. ~ Explain the salient constructional features of a MOSFET. ~ Draw the output i-v characteristics of a MOSFET and explain it in terms of the operating principle of the device. ~ Explain the difference between the safe operating area of a MOSFET and a BJT. ~ Draw the switching characteristics of a MOSFET and explain it. ~ Design the gate drive circuit of a MOSFET. ~ Interpret the manufacturer’s data sheet rating of a MOSFET.. contents: [ Constructional Features of a Power MOSFET ~ Operating principle of a MOSFET ~ Steady state output i-v characteristics of a MOSFET ~ Switching characteristics of a MOSFET ~ Circuit models of a MOSFET cell ~ Switching waveforms ~ MOSFET Gate Drive ~ MOSFET Ratings ] Lesson 7 Insulated Gate Bipolar Transistor (IGBT), objectives: Differentiate between the constructional features of an IGBT and a MOSFET. ~ Draw the operational equivalent circuit of an IGBT and explain its operating principle in terms of the schematic construction and the operational equivalent circuit. ~ Draw and explain the steady state output and transfer characteristics of an IGBT. ~ Draw the switching characteristics of an IGBT and identify its differences with that of a MOSFET. ~ Design a basic gate drive circuit for an IGBT. ~ Interpret the manufacturer’s date sheet of an IGBT.. contents: [ Constructional Features of an IGBT ~ Operating principle of an IGBT ~ Steady state characteristics of an IGBT ~ Switching characteristics of IGBT ~ IGBT ratings and safe operating area ] Lesson 8 Hard and Soft Switching of Power Semiconductors, objectives: To highlight the issues related to device stresses under Hard switching; ~ To suggest means of reducing such stresses with external circuitry; ~ To propose alternative switching methods for stress reduction; ~ Enable the choice of the appropriate switching strategy. contents: [ Soft and Hard Switching ~ Losses in Power Semiconductors ~ Conduction Losses ~ Blocking Losses ~ Switching Losses ~ Diode ~ Soft switching ] Module 2 AC to DC Converters Lesson 9 Single Phase Uncontrolled Rectifier, objectives: Classify the rectifiers based on their number of phases and the type of devices used. ~ Define and calculate the characteristic parameters of the voltage and current waveforms. ~ Analyze the operation of single phase uncontrolled half wave and full wave rectifiers supplying resistive, inductive, capacitive and back emf type loads. ~ Calculate the characteristic parameters of the input/output voltage/current waveforms associated with single phase uncontrolled rectifiers.. contents: [ Terminologies ~ Single phase uncontrolled half wave rectifier ~ Single phase uncontrolled full wave rectifier ~ Split supply single phase uncontrolled full wave rectifier. ~ Single phase uncontrolled full bridge rectifier ] Lesson 10 Single Phase Fully Controlled Rectifier, objectives: Differentiate between the constructional and operation features of uncontrolled and controlled converters ~ Draw the waveforms and calculate their average and RMS values of different variables associated with a single phase fully controlled half wave converter. ~ Explain the operating principle of a single phase fully controlled bridge converter. ~ Identify the mode of operation of the converter (continuous or discontinuous) for a given load parameters and firing angle. ~ Analyze the converter operation in both continuous and discontinuous conduction mode and there by find out the average and RMS values of input/output, voltage/currents. ~ Explain the operation of the converter in the inverter mode.. contents: [ Single phase fully controlled halfwave rectifier ~ Single phase fully controlled bridge converter ~ Operation in the continuous conduction mode ~ Operation in the discontinuous conduction mode ~ Inverter Mode of operation ] Lesson 11 Single Phase Half Controlled Bridge Converter, objectives: Draw different topologies of single phase half controlled converter. ~ Identify the design implications of each topology. ~ Construct the conduction table and thereby draw the waveforms of different system variables in the continuous conduction mode of operation of the converter. ~ Analyze the operation of the converter in the continuous conduction mode to find out the average and RMS values of different system variables. ~ Find out an analytical condition for continuous conduction relating the load parameters with the firing angle. ~ Analyze the operation of the converter in the discontinuous conduction mode of operation.. contents: [ Operating principle of a single phase half controlled bridge converter ~ Single phase half controlled converter in the continuous conduction mode ~ Single phase half controlled converter in the discontinuous conduction mode. ] Lesson 12 Single Phase Uncontrolled Rectifier, objectives: Draw the conduction table and waveforms of a three phase half wave uncontrolled converter supplying resistive and resistive inductive loads. ~ Calculate the average and RMS values of the input / output current and voltage waveforms of a three phase uncontrolled half wave converter. ~ Analyze the operation of a three phase full wave uncontrolled converter to find out the input / output current and voltage waveforms along with their RMS and Average values. ~ Find out the harmonic components in the input / output voltage and current waveforms of a three phase uncontrolled full wave converter. ~ Analyze the operation of a three phase full wave uncontrolled converter supplying a Capacitive - Resistive load.. contents: [ Operating principle of three phase half wave uncontrolled rectifier ~ Three phase full wave uncontrolled converter ~ Operation of a 3 phase full wave uncontrolled bridge rectifier supplying an R - L - E load ~ Operation of a three phase uncontrolled bridge rectifier supplying a capacitive load ] Lesson 13 Operation and Analysis of the Three Phase Fully Controlled Bridge Converter, objectives: Draw the circuit diagram and waveforms associated with a three phase fully controlled bridge converter. ~ Find out the average, RMS valves and the harmonic spectrum of the output voltage / current waveforms of the converter. ~ Find out the closed form expression of the output current and hence the condition for continuous conduction. ~ Find out the displacement factor, distortion factor and the power factor of the input current as well as its harmonic spectrum. ~ Analyze the operation of higher pulse number converters and dual converter. ~ Design the triggering circuit of the three phase fully controlled bridge converter.. contents: [ Operating principle of 3 phase fully controlled bridge converter ~ Analysis of the converter in the rectifier mode ~ Analysis of the converter in the inverting mode. ~ Higher pulse number converters and dual converter ~ Gate Drive circuit for three phase fully controlled converter] Lesson 14 Operation and Analysis of Three Phase Half Controlled Converter, objectives: Draw the circuit diagram and waveforms of different variables associated with a three phase half controlled converter. ~ Identify the constructional and operational difference between a three phase fully controlled and half controlled converter. ~ Calculate the average and RMS value of the output dc voltage. ~ Calculate the displacement factor, distortion factor and power factor of the input ac line current. ~ Calculate the Fourier series components of the output voltage and input current waveforms. ~ Derive the closed form expression for output dc current and hence identify continuous or discontinuous conduction mode of the converter.. contents: [ Operating principle of three phase half controlled converter ~ Analysis of three phase half controlled converters ] Lesson 15 Effect of Source Inductance on the Performance of AC to DC Converters, objectives: Draw the voltage and current waveforms associated with a converter taking into account the effect of source inductance. ~ Find the average output voltage of the converter as a function of the firing angle and overlap angle. ~ Estimate overlap angles under a given operating condition and hence determine the turn off time available for the thyristors. ~ Draw the dc equivalent circuit of a converter and parameterize it. ~ Find out the voltage stress on the thyristors due to commutation overlap.. contents: [ Single phase fully controlled converter with source inductance ~ Three phase fully controlled converter with source inductance ] Lesson 16 Power Factor Improvement, Harmonic Reduction, Filter, objectives: Schemes for the improvement of power factor in AC-DC converters. ~ Methods for harmonic reduction in the current waveforms of the converters. ~ Types of f ilters used to obtain ripple free (dc) output voltage and currents, reducing the harmonics.. contents: [ Power Factor Improvement ~ Extinction Angle Control ~ Symmetrical Angle Control ~ Pulse Width Modulation (PWM) Control ~ Sinusoidal Pulse Width Modulation (SPWM) Control ~ Low Pass (L-C) Filter ~ Two Stage Filter ~ Harmonic Reduction ~ Active Shaping of Input (line) Current ] Module 3 DC to DC Converters Lesson 17 Types of Basic DC-DC Converters, objectives: Three basic types of dc-dc converter circuits - buck, boost and buck-boost ~ The expressions for the output voltage in the above circuits, with inductive (R-L) and battery (or back emf = E) load. contents: [ DC-DC Converters ~ Buck Converters (dc-dc) ~ Boost Converters (dc-dc) ~ Buck-Boost Converters (dc-dc) ~ Control Strategies ~ Time-ratio Control ~ Constant Frequency Operation ~ Variable Frequency Operation ~ Current Limit Control ] Lesson 18 Analysis of Buck Converter (DC-DC) Circuit, objectives: Derivation of the expressions for the maximum and minimum load currents ~ Calculation of the following: the duty ratio for the limit for continuous conduction, the average value and the ripple factor of the load current, the harmonic components of the output voltage waveform. contents: [ Buck Converter (DC-DC) ~ Maximum and Minimum Values of the Load Current ~ The Duty Ratio (k) for the Limit of Continuous Conduction ~ The Average Value of the Output Current ~ Fourier Analysis of the Output Voltage Waveform ] Lesson 19 Commutation of Thyristor-Based Circuits Part-I, objectives: Requirements to be satisfied for the successful turn-off of a SCR ~ The turn-off groups as per the General Electric classification ~ The operation of the turn-off circuits ~ Design of a SCR commutation circuit. contents: [ Classification of forced commutation methods ~ Class A, Self commutated by resonating the load ~ Class B, Self commutated by an L-C circuit ~ Class C, C or L-C switched by another load-carrying SCR ~ Class D, L-C or C switched by an auxiliary SCR ~ Class E - External pulse source for commutation ~ Class F, AC line commutated ~ Rate of rise of forward voltage, dv/dt ] Lesson 20 Commutation of Thyristor-Based Circuits Part-II, objectives: Practical significance of commutation ~ Limitations of line commutation ~ Ability to determine commutation interval ~ Insight to different methods of commutation ~ Consequences of the commutating methods on device stresses. contents: [ Commutation in PAC ~ Input voltage waveform distortion ~ Three-phase converters ~ Commutation in DC-DC Choppers ~ Practice Problems with Answers and Questions ] Lesson 21 Introduction to Switched-Mode Power Supply (SMPS) Circuits, objectives: Identify the basic elements in a regulated power supply ~ Explain the basic principle of operation of linear and switched mode power supplies ~ Compare the merits and demerits of SMPS vis-Ã -vis linear power supplies ~ Interpret Power supply specifications. contents: [ Introduction to regulated dc power supplies ~ Linear regulated power supply ~ Switched Mode Power Supply (SMPS) ~ SMPS versus linear power supply ~ Hybrid (SMPS followed by linear) power supply ~ Multiple output SMPS ~ Resonant Mode Power Supplies ] Lesson 22 Fly-Back Type Switched Mode Power Supply, objectives: Identify the topology of a fly-back type switched mode power supply circuit. ~ Explain the principle of operation of fly-back SMPS circuit. ~ Calculate the ratings of devices and components used in fly-back converter for the specified input and output voltages and for the required output power. ~ Design a simple fly-back converter circuit.. contents: [ Basic Topology of Fly-Back Converter ~ Circuit Equations Under Continuous-Flux Operation ~ Circuit Equations Under Discontinuous-Flux Mode ~ Continuous Versus Discontinuous Flux Mode of Operation ~ A Practical Fly-Back Converter ] Lesson 23 Forward Type Switched Mode Power Supply, objectives: Identify the topology of a forward type switched mode power supply circuit. ~ Explain the principle of operation of a forward dc-to-dc power supply. ~ Calculate the ratings of devices, components, transformer turns ratio for the given input and output voltages and the required output power. ~ Design a simple forward type switched mode power supply circuit.. contents: [ Practical Topology of A Forward Converter Circuit ~ Selection of Transformer Turns Ratio ~ Selection of Filter Circuit Inductor and Capacitor ] Lesson 24 C uK and Sepic Converter, objectives: Compare the advantages and disadvantages of ??CuKand Sepic converters with those of three basic converters. ~ Draw the circuit diagrams and identify the operating modes of ??CuKand Sepic converters. ~ Draw the waveforms of the circuit variables associated with ??CuKand Sepic converters. ~ Calculate the capacitor voltage ripples and inductor current ripples in ??CuKconverter.. contents: [ Analysis of C uK converter ~ Expression for average output voltage and inductor currents ~ Current ripple and voltage ripple calculations ~ The SEPIC Converter ] Lesson 25 Design of Transformer for Switched Mode Power Supply (SMPS) Circuits, objectives: Explain the underlying principles behind the design of a high frequency transformer and inductor. ~ Do a preliminary design of a high frequency transformer for some popular configurations of SMPS circuits. ~ Do a preliminary design of a high frequency inductor. ~ Estimate the size of an SMPS transformer of some given VA rating.. contents: [ Recapitulation of Governing Equations for Utility Transformer ~ Derivation of Design Equations for SMPS Transformer ~ Transformer with Square-Wave Voltage and Bipolar Flux ~ Transformer with Unipolar Flux ~ Design of Inductor-Transformer ~ Transformer Winding ] Module 4 AC to AC Voltage Converters Lesson 26 AC to AC Voltage Converters, objectives: AC-AC power conversion topologies at fixed frequency ~ Power converter options available for the conversion ~ Ability to formulate equations describing the current waveform for the PAC ~ Ability sketch the current waveform by observation of the circuit ~ Ability to assess the performance of the converter of the topologies. contents: [ Operation with resistive loads ~ Power Factor ~ Operation with inductive loads ~ AC-AC Chopper ~ PAC as a static switch ] Lesson 27 Three-phase AC Regulators, objectives: The circuits used for the three-phase ac regulators (ac to ac voltage converters) ~ The operation of the above circuits with three-phase balanced resistive (R) load, along with the waveforms ~ The important points of comparison of the performance with different types of circuits. contents: [ Three-phase AC Regulators ~ Three-phase Delta-connected AC Regulator with Balanced Resistive Load ~ Comparison of the Different Circuits used for Three-phase AC Regulators ] Lesson 28 Phase Angle Control in Triac-based Single-phase AC Regulators, objectives: The circuit used for the phase angle control in triac-based single-phase ac regulators (ac to ac voltage converters) ~ The operation of the various blocks used in the circuit, along with the waveforms ~ The harmonic analysis of the output voltage of a single-phase ac regulator with resistive load. contents: [ Phase Angle Controller Circuit for Triac-based Single-phase AC Regulator ~ TRIAC ~ DIAC ~ Harmonic Analysis of the Output Voltage Waveform ~ ] Lesson 29 Introduction to Cyclo-converters, objectives: The cyclo-converter circuits - basic principle of operation ~ The circuit for the single-phase to single-phase cyclo-converter using thyristors ~ The operation of the above cyclo-converter circuit, along with the voltage waveforms. contents: [ Cyclo-converter Basic Principle of Operation ~ Single-phase to Single-phase Cyclo-converter ~ Discontinuous load current ~ Continuous load current ~ Advantages and Disadvantages of Cyclo-converter ~ Advantages and Disadvantages of DC Link Converter ] Lesson 30 Three-phase to Single-phase Cyclo-converters, objectives: The three-phase to single-phase cyclo-converter circuit, using two three-phase full-wave thyristorised bridge converters ~ The operation of the above cyclo-converter circuit, along with the voltage waveforms. contents: [ Three-phase to Single-phase Cyclo-converter ~ Circulating Current Mode of Operation ~ Cyclo-converter, using two three-phase half-wave converters ] Lesson 31 Three-phase to Three-phase Cyclo-converters, objectives: The three-phase to three-phase cyclo-converter circuit, using six three-phase half-wave thyristorised converters ~ The operation of the above cyclo-converter circuit ~ The analysis of the cyclo-converter output waveform. contents: [ Three-phase to Three-phase Cyclo-converter ~ Analysis of the Cyclo-converter Output Waveform ] Lesson 32 Control Circuit for Three-phase to Three-phase Cyclo-converters, objectives: The control circuits used for the three-phase to three-phase cyclo-converters using two three-phase converters, to generate the firing pulses for the thyristors ~ The functional blocks, including the circuit and waveforms. contents: [ Control Circuit for Cyclo-converters ~ Synchronising Circuit ~ Reference Voltage Sources ~ Logic and Triggering Circuit ~ Circuit for Converter Group Selection ] Module 5 DC to AC Converters Lesson 33 Introduction to Voltage Source Inverters, objectives: Identify the essential components of a voltage source inverter. ~ Explain the principle behind dc to ac conversion. ~ Identify the basic topology of single-phase and three-phase inverters and explain its principle of operation. ~ Explain the gate drive circuit requirements of inverter switches.. contents: [ How to Get AC Output From DC Input Supply? ~ What If The Load Is Not Resistive? ~ General Structure of Voltage Source Inverters ~ Need For Isolated Gate-Control Signals For The Switches ~ Classification of Voltage Source Inverters ] Lesson 34 Analysis of 1-Phase, Square - Wave Voltage Source Inverter, objectives: Explain the operating principle of a single-phase square wave inverter. ~ Compare the performance of single-phase half-bridge and full-bridge inverters. ~ Do harmonic analysis of load voltage and load current output by a single-phase inverter. ~ Decide on voltage and current ratings of inverter switches.. contents: [ Harmonic Analysis of The Load Voltage And Load Current Waveforms ~ Time Domain Analysis ~ Frequency Domain Analysis ~ Analysis Of The Single-Phase Full Bridge Inverter ~ Voltage And Current Ratings Of Inverter Switches ~ Applications Of Square Wave Inverter ] Lesson 35 3-Phase Voltage Source Inverter With Square Wave Output, objectives: Explain the operating principle of a three-phase square wave inverter. ~ Understand the limitations and advantages of square-wave inverters. ~ Do harmonic analysis of load voltage and load current output by the three-phase sq. wave inverter. ~ Decide on voltage and current ratings of inverter switches.. contents: [ Determination Of Load Phase-Voltages ~ Harmonic Analysis Of Load Voltage Waveforms ~ Voltage And Current Ratings Of Inverter Switches ~ Use And Limitations Of 3-Phase Square Wave Inverter ] Lesson 36 3-Phase Pulse Width Modulated (PWM) Inverter, objectives: Explain the philosophy behind PWM inverters. ~ Understand the advantages and disadvantages of PWM inverters. ~ Compare the quality of output voltage produced by different PWM inverters ~ Decide on voltage and current ratings of inverter switches.. contents: [ Nature Of Pole Voltage Waveforms Output By PWM Inverters ~ Harmonic Analysis Of Pole Voltage Waveform ~ Trade Off Between Low Order And High Order Harmonics ~ Brief Description Of Some Popular PWM Techniques ~ Two-Level Versus Three-Level PWM Inverters ~ Considerations On Switch Voltage And Current Ratings ] Lesson 37 Sine PWM and its Realization, objectives: Explain the concept of sine-modulated PWM inverter ~ Design a simple controller for the sine-PWM inverter ~ Calculate output voltage magnitude from the inverter operating parameters ~ Compare sine-modulated PWM inverter with square wave inverter. contents: [ Analysis Of The Pole Voltage Waveform With A Dc Modulating Signal ~ Pole Voltage Waveform With Sinusoidal Modulating Signal ~ What Is Modulation Index? ~ What Is Over-Modulation? ~ A 1-Phase Sine-PWM Inverter Of H-Bridge Topology ~ Generation Of 3-Phase Sine-PWM Waveform ~ A Typical Circuit For Generation Of PWM Waveforms ] Lesson 38 Other Popular PWM Techniques, objectives: Explain the concept of sine+3rd harmonic modulated PWM inverter ~ Explain Space-Vector based PWM (SVPWM) technique ~ Estimate output voltage of the inverter using above PWM techniques ~ Compare at least five different PWM techniques for a 3-phase inverter. contents: [ How To Get More Output Voltage From The Same DC Bus Voltage? ~ Sine + 3rd Harmonic PWM Technique ~ Space Vector PWM (SV-PWM) Technique ~ Smoothly Rotating Space Voltage Vector From Inverter ~ Algorithm For Producing Sinusoidal Output Voltages Using SV-PWM ~ Some Other Popular PWM Techniques ~ Selective Harmonic Elimination Technique ~ Current Controlled PWM (CCPWM) Technique ] Lesson 39 Current Source Inverter, objectives: The circuit for single-phase Current Source Inverter (CSI) using thyristors ~ Auto-Sequential Commutated mode of operation for 1-ph. Inverter (ASCI), with waveforms ~ Three-phase Current Source Inverter (CSI) - circuit and operation, with waveforms. contents: [ Single-phase Current Source Inverter ~ Three-phase Current Source Inverter ] Lesson 40 Load-commutated Current Source Inverter (CSI), objectives: Study of the circuit and operation for Load-commutated Current Source Inverter (CSI). contents: [ Load-Commutated CSI ] Do Enjoy.