Đồ-án-điện-tử-công-suất mạch chỉnh lưu tia một pha

1.2 Speed – torque equation of DC motors 1.2.1 Electrical motor characteristics The mechanical characteristic of electric motors is the linearity between thespeed and the speed of the mo

CHAPTER1: OVERVIEWOF DC MOTORS 5

1.1 General structure 5

1.1.1 Concept 5

1.1.2 Components of dc motor 5

1.1.3 Classification of DC motors 5

1.1.4 Principle of DC motors 6

1.2 Speed – torque equation of DC motors 6

1.2.1 Electrical motor characteristics 6

1.2.2 Wiring schematic diagram of an independent dc motors 6

1.2.3 Natural Speed -Torque characteristic 7

1.2.4 Artificial Speed -Torque characteristic 7

1.3 Methods of adjustment change engine speed DC 7

1.3.1 Change the auxiliary resistance in the armature circuit 7

1.3.2 Change of motor magnetic flux 8

1.3.3 Change of motor armature voltage 9

1.4 Conclusion 10

CHAPTER 2: ADJUSTMENT OF THE 1 PHASE FULLY CONTROLLED BRIDGE RECTIFIER 11

2.1 General introduction 11

2.1.1 Concepts 11

2.1.2 Classification 11

2.1.3 Characteristics of voltage and rectifying current 11

2.2 Adjusting the floor screen 1 full control 12

2.2.1 Principle circuit diagram 12

2.2.2 Working principle 12

2.2.3 Rectifier voltage and current 13

2.2.4 Coincidence phenomenon 13

2.3 Adjustment control methods 14

2.3.1 General concept 14

2.3.2 Principle of linear vertical control 15

2.3.3 Principle of vertical control arccos 15

CHAPTER 3: DESIGN AND SELECTION OF DYNAMIC COMPONENTS 17

3.1 Introduction 17

3.1.1 Dynamic circuit 17

3.1.2 Function 17

3.2 Calculate dynamic circuit 17

3.2.1 Selection of Thyristor 17

3.2.2 Calculation of rectifier transformers 18

3.2.3 Filter design 20

3.3 Conclusion 21

CHAPTER 4: DESIGN OF CONTROL NETWORK PART 23

4.1 General introduction 23

4.1.1 Thyristor control block diagram 23

4.1.2 Requirements of the control circuit 23

4.1.3 Control circuit duties 23

4.1.4 Control principles 24

4.2 Principles of operation from zone 24

4.2.1 Copper phase stitching 24

4.2.2 The stage of comparison 25

4.2.3 Stitch creating beam pulse 25

4.2.4 Amplifier stitching 26

4.2.5 Control circuit diagram 27

4.3 Contributing circuit parameters 28

4.3.1 Pulse transformer calculation 28

4.3.2 Calculate the final amplification stage 28

4.3.3 Calculation of beam pulse generator selection 29

4.3.4 Compute choosing the comparison layer 30

4.3.5 Calculation of choosing a synchronous stage 30

4.3.6 Calculate synchronous stitching 2 half cycle 31

4.3.7 calculate serrated 2 half cycle 32

4.3.8 Choosing Diode for rectifier 32

CHAPTER 5: DESIGN OF DYNAMIC COMPONENTS 34

5.1 Generation introduction 34

5.2 Over current protection 34

5.3 Protect circuit chart of the motion circuit 35

THE PREFACE

In the technological innovation and modernization of water, the problem ofapplying science and technology to regulated products is the most urgent issue Alongwith the development of a number of industries such as electronics, informationtechnology Industry automation company has also developed dramatically Processproduction automation is very popular, can replace human labor, high productivityagain, good product quality

Along with the development of the power electronics industry, theapplication of DC motors and industry is very important The use of 1-way motors formany purposes such as to ensure the technological requirements of the load Tounderstand the role of electric drive system, power electronics and one-way electricmotor through this subject project, under the guidance of Mr Nguyen Ngoc Khoatwith the main content of the subject:

Design a rectifier to control speed of a separately excited DC motor with thefollowing parameters:

1) Single-phase controlled bridge rectifier;

2) DC motor: P = 4 kW, Uđm = 180V, nđm = 980v/p, Iđm = 6A, Mc =75%Mđm

I sincerely thank Mr Nguyen Ngoc Khoat for his dedication and help forguiding, helping and creating favorable conditions for us to complete this topic

We sincerely thank!

Hà Nội, December 18th , 2020Students :

Tăng Thị Như QuỳnhTrần Thị Thu Thảo

CHAPTER1: OVERVIEWOF DC MOTORS 1.1 General structure

Figure 1 2: Construction of DC motors

1- Plate, 2 - Main pole with field coil, 3 - Commutating with reel, 4 - Ballbearing box, 5 - Laminated, 6 - Armature roll, 7- Brush equipment, 8 - commutator, 9

- Axis, 10 - Terminal box cover

1.1.3 Classification of DC motors

DC motors are classified according to excitation into the following categories:

 Independent DC motor: The armature and the exciter are supplied from twoseparate sources

 Parallel dc electric motor: The field coil is connected in parallel with thearmature

 Series magnetic dc motor: The exciter coil is connected in series with thearmature

 Combined d.c electric motor: Consists of two excitation windings, oneconnected parallel to the armature, one connected in series with thearmature

1.1.4 Principle of DC motors

DC motors operate based on the effect of a magnetic field on the wire framewith electric current flowing through the magnetic field When operating DC motorsturn the electric current of direct current into mechanical energy

1.2 Speed – torque equation of DC motors

1.2.1 Electrical motor characteristics

The mechanical characteristic of electric motors is the linearity between thespeed and the speed of the motor:M = f(ω).ω).)

1.2.2 Wiring schematic diagram of an independent dc motors

Independent DC motor: DC power is supplied to the armature and supplied tothe exciter independently

Figure 1 3: Wiring schematic diagram of separatedly excited dc motor

 Equation of voltage balance:

Uư = Eư +(ω).Rư + Rf).Iư (1.1)

 Electromotive force of the engine armature:

Figure 1 4: Speed –Current

 Speed – Torque characteristic :

ω= U ư

K ϕ−

R ư+R f

(K ϕ)2 M (ω).1.5)

Figure 1 5: Speed – Torque

1.2.3 Natural Speed -Torque characteristic

Natural mechanical properties:ω = f (ω).M) when parameters such as U, I, R ofthe motor are the rated parameters ω on the natural mechanical properties we have arated working point is (ω).M đ m; ω đ m) - Each motor has only 1 natural mechanical property

 Natural Speed –Current characteristic:

1.2.4 Artificial Speed -Torque characteristic

Artificial mechanical characteristics: ω = f (ω).M) when the electrical parametersare not rated parameters or when the electric circuit has been added Rf, Lf - Eachmotor has many artificial mechanical properties

 Speed -Torque characteristic:

ω= U ư

K ϕ−

R ư+R f

(K ϕ)2 M (ω).1.8)

1.3 Methods of adjustment change engine speed DC

1.3.1 Change the auxiliary resistance in the armature circuit

Speed -Torque characteristic:

 Ideal constant idle speed.

 Only allows speed change adjustment on the downward side

 As Rf increases, the greater the slope of the mechanical properties, the softerthe mechanical properties ⇒ the lower the speed stability, the greater thespeed error

 Power loss in the form of heat on the auxiliary resistor

If we increase Rfto a certain value, it will make M ≤ Mc so that the motor willnot spin and the motor is in short circuit mode (ω).ω) = 0).From now on, we can changethe Rf and the speed will remain 0, which means the engine speed cannot be adjustedanymore.Therefore this adjustment method is not a radical adjustment method

Advantages: The changing device is very simple, often used for crane motors,

elevators, lifters, and excavators

Disadvantages: The lower the adjustment speed, the greater the input

resistance value, the softer the mechanical properties, the reduced stiffness leads topoor speed stability when the load changes poorly The auxiliary losses are very largewhen adjusting, the lower the speed, the higher the auxiliary losses

⇒ The Rfchange method is suitable only when starting the engine.

1.3.2 Change of motor magnetic flux

Speed -Torque characteristic:

Figure 1 7: Speed adjustment characteristic by change ϕ

Adjustment characteristics:

 Decreasing the flux results in inversely proportional change of speed.The lower the flux, the more ideal idle speed increases, and the greaterthe motor speed

 Constant short-circuit current

 Mechanical property stiffness decreases with decreased flux

If is too small, it may cause the motor speed to exceed the permissible limit, ormake the switching condition worse due to the increased armature current.Thus, toensure normal switching, it is necessary to reduce the armature current ⇒ the torque

on the motor shaft rapidly decreases ⇒ the motor is overloaded

Advantages: The speed adjustment method by varying the flux can be

infinitely adjusted and gives the speed greater than the basic speed.The bouncingmethod is often used for machines such as: universal grinder, bed planer, Theadjustment is done on the exciter circuit so the loss of energy is low, the equipment issimple so the price is low

Disadvantages: Due to deep adjustment, β decreases, large static error, less

stable with high speed.That means the deeper the adjustment, the larger Δω) So themore the characteristic is that the smaller the torque is until the smaller the load torque,the motor cannot run

1.3.3 Change of motor armature voltage

Speed -Torque characteristic:

ω= U ư

K ϕ−

R ư+R f

(K ϕ)2 M (ω).1.11)

We see that when Uưchanges, ω ochanges and Δω) = const, so we will be adjustedparallel by the property lines.But if you want to change Uư, you must have a DC powersupply that can change the output voltage, often using a converter.

Figure 1 8: Speed adjustment characteristic by U ư change

Adjustment characteristics:

 The motor speed increases / decreases in the direction of increasing / decreasingthe armature voltage

 Variable both ideal no-load speed ω0, and short-circuit current

 Mechanical property hardness remains constant throughout the adjustmentrange

 Speed can only be adjusted on the downward side because it can only bechanged with

Uư≤Uđm

Advantages: The speed control method by varying the motor armature voltage

will keep the characteristic line stiffness, so it is widely used in metal cuttingmachines.Ensuring economy, low energy loss, wide range of adjustment.If combinedwith the flux adjustment method, we can adjust the higher and smaller speeds than therated speed

Disadvantage: This method requires a power supply that can smoothly change

voltage

1.4 Conclusion

Through the analysis of the three methods of adjusting the speed of a DCelectric motor, the method of controlling the motor speed by changing the armaturevoltage is the best and most radical Therefore, we choose the method of varyingarmature voltage to control the speed of DC motors

CHAPTER 2: ADJUSTMENT OF THE 1 PHASE FULLY CONTROLLED

BRIDGE RECTIFIER 2.1 General introduction

2.1.2 Classification

Based on the number of phases supplied to the rectifier valves: 1 phase, 2phase, 3 phase, 6 phase

Based on the type of semiconductor valve:

 Uncontrolled rectifier circuit

 Full control rectifier circuit

 Semi-controlled rectifier circuit

Based on valve diagram:

 Beam diagram: Number of valves is equal to number of phasessupplied.The valves are matched with one end: Common anode orcommon cathode

 Spherical diagram: Half of the valves have common Anode, half of thevalves have common cathode

2.1.3 Characteristics of voltage and rectifying current

2.1.3.1 Rectifier voltage

u d=U d+u σ(2.1)

ud: The instantaneous value of the rectifier voltage

uσ: Alternating components

Ud: Average value of rectifier voltage

p= f σ (1)

f (ω).2.3)fσ(ω).1): Frequency of the AC component's 1st harmonic waveud

f: Grid voltage frequency

The effective value of the voltage rectifier:

2.1.3.2 Rectifier current

i d=i dσ+I d(2.5)

id: The instantaneous value of the rectifying current.

idσ: Alternating components

I σ(n)= U σ (n)

√R2+[ω σ(n)L]2 (ω).2.6)Uσ(ω).n): The effective value of the nth harmonic wave component of alternatingvoltage rectifier

ω σ(n): Angular frequency of a harmonic wave n-order AC component.

Flickering of the load current: Due to the ac component of the rectifier voltage

If L → ∞ ⇒Iσ(ω).n) → 0⇒ id= Id⇒Absolutely flat lines

2.2 Adjusting the floor screen 1 full control

2.2.1 Principle circuit diagram

In (ω).0 ÷ π) ⇒ u1> 0 ⇒Suppose T2, T4 are conducting the reactive current

⇒ id = iT2 = iT4 = ipk> 0; T1, T3 are locked, ud< 0.

θ1≡α ⇒ u1> 0 and has control pulses⇒ T1, T3open⇒ id = iT1 = iT3> 0, T2, T4close,ud> 0

In (ω).π ÷ 2 π)⇒ u2> 0 ⇒T1, T3T1, T3 are still conducting reactive current

⇒ id = iT1 = iT3 = ipk> 0, ud< 0

θ2≡(π +α)⇒ u2> 0 and has control pulses⇒ T2, T4open

⇒ id = iT2 = iT4> 0; T1, T3close, ud> 0.

Just like that, we will open control each pair of T1, T3, then T2, T4 separated

by an angle π

2.2.3 Rectifier voltage and current

 Average value rectifier voltage:

Th

Figure 2 4: Wave form graph when conduction occurs

Suppose T1, T3 are open to flow iT1=iT3=Id Whenθ=π +αPulse openT2, T4.Because there are L =>iT1, iT3 does not drop suddenly to 0 and line iT2, iT4 does not asudden increase from 0 ÷ Id At this time, all 4 valves are open to prevent flow, theload is shorted Ud = 0

Consequences of the phenomenon of coincidence:

 The switching phenomenon reduces the load voltage

 The switching phenomenon restricts the control voltage control range andthus limits the rectifier voltage control range

 Switching phenomenon distorts the supply voltage

2.3 Adjustment control methods

2.3.1 General concept

The control pulse applied to the thyristor at the time the voltage applied to thethyristor anode must be pulsed positive

⇒Must know when the voltage applied to the thyristor is positive

⇒Must have synchronous voltage: synchronous with the lock voltage placed onthe thyristor Diagram of pulse generation - controller:

Figure 2 5: Thyristor control block diagram

2.3.2 Principle of linear vertical control

Figure 2 6: Principle of linear vertical control

Control voltage Uc is direct voltage

Synchronous voltage Udb is the jagged voltage

Comparative voltageuss = Uc - Udb

When Uc = Udb ⇒ uss = 0 is the time of comparison creating control pulse.Control angle:α=π × U c

U dbM=k ×U c

Rectifier voltage: Ud = Udo.cos(ω).kUc)

2.3.3 Principle of vertical control arccos

Figure 2 7: Principle of vertical control arccos

Control voltage Uc is DC voltage

Synchronous voltage Udb is a cosin: Udb = Umcosθ

Comparative voltageuss = Uc - Udb

When Uc = Udb ⇒ uss = 0 is the time of comparison creating control pulse.Whenθ=α => Uc = Udb =Umcosα

⇒Control angle α=arccos U c

U m

Rectifier voltage: U d=U do × U c

U m

 Convert the voltage of the AC grid U1 to voltage U2 suitable for the load.

 Change the number of phases of the grid source (ω).1,2,3,6,12,… phase)

 Isolate from grid voltage

Rectifier devices:The semiconductor valves (ω).Diode, thyristor,….)

Filter :Help rectifier output voltage to be flat DC as required

3.2 Calculate dynamic circuit

3.2.1 Selection of Thyristor

When choosing a valve based on two basic parameters and most importantly,the current through the valve and the maximum reverse voltage that the valve canwithstand

Reverse voltage on the valve:

U ngmax=K nv ×U2 (ω).3.1)

1-phase bridge rectifier we have:

U d=2√2

π × U2× cosα (ω).3.2)

In the calculation we have to calculate such that Ud is at maximum, cosα=1

K nv=√2=1,41 : Reverse voltage coefficient

K u=2√2

π =0,9 : Circuit voltage coefficient

U d : Average voltage rectifier

U2 : AC source voltage

U ngmax=1,41×U d

0,9=1,41 ×

2200,9=344,6(V ) (ω).3.3)

Valve working current:

K hdv: Effective coefficient for 1-phase bridge diagramKhdv=√2

There are the following figures:

 Valve reverse voltage: U ngmax=600(V )

 Maximum working current: I hdmax=25( A)

 Control pulse current: I Gmax=180 (mA)

 Control pulse voltage:U Gmax=3(V )

 Maximum voltage drop on thyristor in conductive state:

∆ U max=2(V )

 Leakage current: I rmax=4 (mA)

 Speed of voltage variation dU dt =200(V /s)

 Time switching: t cm=10 (μSS)

 Permitted working temperature: T max=125℃

 Peak current pulse: I pikmax=180( A)

 Maintenance current: I h=150 (mA)

3.2.2 Calculation of rectifier transformers

3.2.2.1 Rectifier voltage on load

U d 0 × cosα min=U d+2 × ∆ UV+∆ U ba+∆ U dn (ω).3.9)

In which:

α min = 10o: storage angle when there is a drop in the network voltage

∆ U V=2 (V ) voltage drop on thyristor

∆ U dn=0(V )voltage drop on connection line

∆ U ba=∆ U r+∆ U xvoltage drop across the transformer resistance andresistance.Preliminary selection is about (ω).5 - 10)%

3.2.2.3Apparent Capacity of the MBA

S= K s × P dMax=1,23× 6390,86=7860,76 (VA) (ω).3.12)

K s:Power factor according to the 1-phase bridge schemeK s=1,23

P dMax:Load capacity at maximum

3.2.2.4Preliminary calculation of magnetic circuits

Q Fecylindrical cross-section of transformer steel core:

Q Fe=k Q ×√m × f S (ω).3.13)kQ: The coefficient depends on the cooling method (ω).kQ = 6 dry transformer)m: the number of phases of the transformer

f: frequency

Q Fe=6 ×√7860,761 ×50 =75,23(c m

2)

3.2.2.5Transformer winding calculation

Primary winding voltage:

The number of turns per coil is calculated:

4

4,44 × f ×Q Fe × B(ω).3.14)Inside:

W: number of turns to be calculated

U: coil voltage to be calculated

B: sympathy (ω).usually choose between 1T ÷ 1.8T) Choose B = 1 (ω).T)

Number of primary coil turns: