Introduction

                     Introduction

Advancement of inverter technique has made available the ac power supply, whose output voltage and current can be controlled as vector quantities of variable amplitude and frequency. Controllability of ac motors are now invading into application areas where dc motor control have been predominantly used. However it seems that ac motor control technique has not been well grounded on a sound theoretical base. The problem is that transient phenomena of ac motors have not been well analyzed. The conventional ac motor theories have not been well analyzed.                          The conventional ac motor theories have been lacking in their ability to analyze electromagnetic transient phenomena of ac motors. Most control theories of ac motors have been based on the equivalent two phase machine theory, which is sometimes called d,q axes theory. Its characteristic equation is of 4^th degree and thus the theory is unwieldy. It is being tried to replace the two phase theory with the space vector method. But it relies too much on physical pictures and is not mathematically rigorous in derivation of circuit equations of ac motors. The spiral vector method will simplify analysis of electro magnetic transient phenomena ac circuits and ac machines, just as the phasor notation simplified analysis of steady states of ac circuits and machines. Analytical results obtained by the spiral vector have revealed superior control features of ac motors. The spiral vector method will also bring about a new development in the ac circuit theory, where steady state and transient state are separately treated by the separately treated by the separate two theories, the ac circuit which uses the phasor notation, and the transient theory, which uses instantaneous real values. The spiral vector will unify the two theories into the spiral vector theory of ac circuit and machine.          

                           In industry application the variable speed drive use often a vector control of induction machine. The field orientation defines conditions for decoupling the field from the toque control the field oriented induction motor emulates separately exited DC motor in two aspects

·         Both the magnetic field and the torque developed in the motor can be controlled independently

·         Optimal conditions for torque production, resulting in the maximum torque per Unit samplers, occur in the motor both in steady state conditions and transient   Conditions of an operation.

A vector control is obtained by the conventional theories which are based on two axis method, they involve complicated variable transformations, which are not so successful in analyzing the machine. In this work we propose a vector control of induction machine by a spiral vector theory. The application of this theory conduct to eliminate the Park’s Transformation to make the regulation and to obtain a good decoupling between the air gap flux and electromagnetic torque

VECTOR CONTROL OF INDUCTION MOTOR BY A

                         CONTENTS

 Introduction

1.Traditional nine level inverter

2.Cascaded  31-level inverter with high power quality

3.Experimental setup

4.Switching pattern

5.Harmonic analysis

6.Simulation of  31-level inverter

Algorithm flowchart

“c” program

simulation results           

7.Experimental verification

8.Conclusions

           

List  Of  Symbols

 : Leakage inductance of phase a

 : Resistance of phase a

 :  Leakage inductance of phase r

R₂  :   Resistence of phase r

M_rs :   Maximum value of mutual inductance between stator and rotor windings

q  :    w_mt

P  :    pair pole number

J   :    Total constant mechanical inertia

f_r   :    Total friction coefficient s

T_r  :     Resistance torque

W_r  :     Mechanical speed

T_em :     Electromagnetic torque(N.m)

j₀   :    Air-gap flux(Wb)

j_0ref  :   Air-gap flux of reference(Wb)

T_emref  :  Electromagnetic torque of reference(N.m)

                        ABSTRACT

AC motors, whilst being very economical, rugged and reliable due to the absence of commutators and brushes, have inherently poor dynamic behavior. However, the dynamic behavior can be made to match that of an equivalent separately excited DC motor using Field Orientated or Vector Control.In this project vector control of induction machine by a spiral vector theory is proposed. This method permits to establish the performance equations of the induction machine in function only one phase variables of the stator and rotor.   The obtained equations are basically using in field oriented control. The   simulation results give a good decoupling between the air gap flux and electromagnetic torque and it sufficient to track one voltage quantities   or current to make the regulation in the case of a direct vector control of induction machine.

Make a 100 Watt Transistor Amplifier Circuit…

Whether it’s for your cell phone or your iPod, this transistor amplifier circuit will convert any tiny audio into an ear pounding 100 watts of raw music power. A complete 100w transistor power amplifier schematic is provided here.

Introduction

If we compare the simplicity of the proposed 100w transistor power amplifier schematic design to its power output, which is a good 100 watts, indeed it looks very impressive.

The entire circuit utilizes commonly available components and may be simply built over a general purpose board. If all the connections are done accurately as shown in the diagram, the circuit should immediately start “pumping” your loud speakers with a high quality music output. I have personally tested this circuit and believe me its response is outstanding, build a couple of them and it becomes compatible with stereo inputs- that also means now you are producing 200 watts of brain-pounding music power.

Let’s examine the circuit functioning.

Circuit Description

At the first glance the circuit rather appears to be unsymmetrical in design, due to an unbalanced looking output stage. However a closer look will prove this wrong. Transistors T9, T10, T11 and T12, T13, and T14 form two well-balanced halves of the circuit, perfectly complementing each other.

The input stage employs the standard R/C filter configuration. R1 and R2 fix the input impedance, and the inclusion of C1 creates a high-pass filter that blocks all frequencies around 1.5 Hz. C1 also functions as an input stage DC bias isolator.

The presence of R2 and C2 ensures no frequency above 250 KHz makes its way into the circuit, thus blocking most of the high frequency RF intrusions.

Transistor T1 and T2 are wired up in a standard differential amplifier mode.

The remaining portion of the circuit is mainly the output stage and is responsible for amplifying the differential stage into the loud speakers.

Specifications:

Power output is 60 watts into 8 Ω and 100 watts into 4 Ω loudspeaker.

Total harmonic distortion is less than 0.01 %.

Frequency range is within 20 Hz and 20 kHz.

The input sensitivity is in the vicinity of 750 mV.

The frequency characteristics lie in between 1 dB from 15 Hz to around 100 kHz.

Due to its very high amplification factor of around 20,000, the output stage may have an ideally low quiescent current drain of about 40 mA.

The quiescent current can be set through P1 with a digital multimeter connected across resistors R6 and R7.

Adjust P1 until the meter reads about 40 mV, corresponding to 50 mA current.

Important Technical Parameters to be Followed

Although the circuit parameters are not critical and may be built over a general purpose board, care should be taken that the component layout does not differ from the circuit diagram by much.

Preferably use separate heatsinks for the transistors T10, T11, T13, T14, to avoid the involvement of messy mica isolators, heatsink paste, etc.

The output stage of the circuit is virtually unaffected by temperature variations, however ideally T8, T9 and T7, T12 may be coupled with each other (by gluing them together) to enhance thermal stability of the circuit.

The output inductor L1 is made by winding 20 turns of 0.8 mm super enameled copper wire right over the resistor R24.

The current consumption may shuffle in between 1 and 3 Amp depending on the volume level of the unit.

Parts List

You will require the following parts to build this 100w transistor power amplifier schematic design.

All resistors are 1/4w, CFR unless otherwise specified.

R1 = 470K,

R2 = 47K,

R3 = 330E,

R4, R5 = 10K,

R6, R7, R20, R21, R22, R23, R24 = 1E/2W,

R8, R17 = 56E,

R9 = 100K,

R10, R11, R12, R13 = 4K7,

R14, R15 = 10K,

R16, R19 = 100E,

R25 = 10E/2W,

P1 = 100E Preset,

C1 = 1µ/25V,

C2 = 1n, CERAMIC,

C3, C4 = 100Pf

C5 = 100n,

C6, C7 = 1000uF/35V,

L1 = see text,

D1, D2 = RED LED 5mm,

Rest of the diodes are = 1N4148,

T1 = Pair of well-matched BC546,

T2 = Pair of well-matched BC556,

T3 = BC557,

T4, T7, T8 = BC547,

T5, T12 = BC556,

T6, T9 = BC546,

T10 = BD140 (Mount over "C" channel heatsink)

T13 = BD139 (Mount over "C" channel heatsink)

T11, T14 = 2N3055 (Mount over large finned-type heatsink)

General Purpose Board,

Power Supply = 25-0-25V, 5 Amp.

Fuse, Mains Cord, Metallic Enclosure, Switch, External Sockets etc....