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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Catalogue

THE PREFACE
In the technological innovation and modernization of water, the problem of
applying science and technology to regulated products is the most urgent issue. Along
with the development of a number of industries such as electronics, information
technology ... Industry automation company has also developed dramatically. Process
production automation is very popular, can replace human labor, high productivity
again, good product quality.
Along with the development of the power electronics industry, the
application of DC motors and industry is very important. The use of 1-way motors for
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

many purposes such as to ensure the technological requirements of the load. To
understand the role of electric drive system, power electronics and one-way electric
motor through this subject project, under the guidance of Mr. Nguyen Ngoc Khoat
with the main content of the subject:
Design a rectifier to control speed of a separately excited DC motor with the
following 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 for
guiding, helping and creating favorable conditions for us to complete this topic.

We sincerely thank!
Hà Nội, December 18th , 2020
Students :
Tăng Thị Như Quỳnh
Trần Thị Thu Thảo

CHAPTER1: OVERVIEWOF DC MOTORS
1.1 General structure
1.1.1 Concept
A DC motor is a DC machine that converts direct current into mechanical
energy.
When a DC machine is operating in the motor mode, the input power is the
electromechanical power and the output power is the mechanical power.

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Figure 1. 1: DC motor
1.1.2 Components of dc motor
DC motors can be divided into two main components: the stationary and the
dynamic part.

Figure 1. 2: Construction of DC motors
1- Plate, 2 - Main pole with field coil, 3 - Commutating with reel, 4 - Ball
bearing 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 two
separate sources.
• Parallel dc electric motor: The field coil is connected in parallel with the
armature.
• Series magnetic dc motor: The exciter coil is connected in series with the
armature.
• Combined d.c. electric motor: Consists of two excitation windings, one
connected parallel to the armature, one connected in series with the
armature.

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

1.1.4 Principle of DC motors
DC motors operate based on the effect of a magnetic field on the wire frame
with electric current flowing through the magnetic field. When operating DC motors
turn 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 the
speed and the speed of the motor:M = f(ω).
1.2.2 Wiring schematic diagram of an independent dc motors
Independent DC motor: DC power is supplied to the armature and supplied to
the exciter independently

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

• Equation of voltage balance:
Uư = Eư +(Rư + Rf).Iư
• Electromotive force of the engine armature:
Eư = K
• The electromagnetic torque of the motor:
M = KIư
• Speed – Current characteristic :

(1.2)

(1.4)

Figure 1. 4: Speed –Current
• Speed – Torque characteristic :
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

(1.5)

Figure 1. 5: Speed – Torque
1.2.3 Natural Speed -Torque characteristic
Natural mechanical properties: = f (M) when parameters such as U, I, R ... of
the motor are the rated parameters on the natural mechanical properties we have a
rated working point is (; ) - Each motor has only 1 natural mechanical property
• Natural Speed –Current characteristic:
(1.6)
• Natural Speed -Torque characteristic:

(1.7)
1.2.4 Artificial Speed -Torque characteristic
Artificial mechanical characteristics: = f (M) when the electrical parameters are
not rated parameters or when the electric circuit has been added Rf, Lf ... - Each
motor has many artificial mechanical properties
• Speed -Torque characteristic:
(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:
(1.9)
We see that when we change Rf, ω_o = const and change, so we will be
adjusted by the same ω_o and steeper as the larger Rf, with the same load, the lower
the
speed.

Figure 1. 6: Speed adjustment characteristic when Rf changes
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Adjustment characteristics:
• 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 softer
the mechanical properties ⇒ the lower the speed stability, the greater the
speed 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 will
not spin and the motor is in short circuit mode (ω = 0).From now on, we can change
the Rf and the speed will remain 0, which means the engine speed cannot be adjusted
anymore.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 to
poor speed stability when the load changes poorly. The auxiliary losses are very large
when 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:
(1.10)
We see that when changes, and Δω both change, so we will get the curves
adjusted gradually and higher than the natural mechanical properties when ϕ is
smaller, with the same load, the higher the speed. when reducing the flux ϕ.

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 greater
the 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, or
make the switching condition worse due to the increased armature current.Thus, to
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

ensure 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 bouncing
method is often used for machines such as: universal grinder, bed planer, ... The
adjustment is done on the exciter circuit so the loss of energy is low, the equipment is
simple 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 the
more 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:
(1.11)
We see that when Uưchanges, changes and Δω = const, so we will be adjusted
parallel by the property lines.But if you want to change Uư, you must have a DC power
supply that can change the output voltage, often using a converter.

Figure 1. 8: Speed adjustment characteristic by Uư change
Adjustment characteristics:
• The motor speed increases / decreases in the direction of increasing / decreasing
the armature voltage.
• Variable both ideal no-load speed , and short-circuit current.
• Mechanical property hardness remains constant throughout the adjustment
range.
• Speed can only be adjusted on the downward side because it can only be
changed with

UưUđm.
Advantages: The speed control method by varying the motor armature voltage
will keep the characteristic line stiffness, so it is widely used in metal cutting
machines.Ensuring economy, low energy loss, wide range of adjustment.If combined
with the flux adjustment method, we can adjust the higher and smaller speeds than the
rated speed.
Disadvantage: This method requires a power supply that can smoothly change
voltage.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

1.4

Conclusion
Through the analysis of the three methods of adjusting the speed of a DC
electric motor, the method of controlling the motor speed by changing the armature
voltage is the best and most radical. Therefore, we choose the method of varying
armature voltage to control the speed of DC motors.

CHAPTER 2: ADJUSTMENT OF THE 1 PHASE FULLY CONTROLLED
BRIDGE RECTIFIER
2.1 General introduction
2.1.1 Concepts
Rectifiers are static converters that convert the energy of a source with
alternating quantities into a source other than DC quantities.
Applications: Power supply for DC loads such as DC motors, battery chargers,
electrolytic plating, DC welding machines, electromagnets, high voltage direct current

transmission,….
2.1.2 Classification
Based on the number of phases supplied to the rectifier valves: 1 phase, 2
phase, 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 phases
supplied.The valves are matched with one end: Common anode or
common cathode.
• Spherical diagram: Half of the valves have common Anode, half of the
valves have common cathode.
2.1.3 Characteristics of voltage and rectifying current
2.1.3.1 Rectifier voltage
ud: The instantaneous value of the rectifier voltage.
uσ: Alternating components.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Ud: Average value of rectifier voltage.
(2.2)
p: Number of pulse pulses of rectifier voltage wave.
(2.3)
fσ(1): Frequency of the AC component's 1st harmonic waveud.
f: Grid voltage frequency.

The effective value of the voltage rectifier:
(2.4)
Uσ: The effective value of the AC component voltage rectifiers.
2.1.3.2 Rectifier current
id: The instantaneous value of the rectifying current.
idσ: Alternating components.
(2.6)
Uσ(n): The effective value of the nth harmonic wave component of alternating
voltage rectifier.
: 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(n) → 0 id= IdAbsolutely flat lines.
2.2 Adjusting the floor screen 1 full control
2.2.1 Principle circuit diagram
(2.7)
(2.8)
(2.9)
(2.10)

Figure 2. 1: Circuit diagram of a fully controlled single-phase bridge rectifier

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

2.2.2 Working principle

Figure 2. 2: Diagram and graph of u, i of single-phase controlled bridge

rectifier
Consider at established work cycles:
In () u1> 0 Suppose T2, T4 are conducting the reactive current
id = iT2 = iT4 = ipk> 0; T1, T3 are locked, ud< 0.
u1> 0 and has control pulses T1, T3open id = iT1 = iT3> 0, T2, T4close, ud> 0.
In () u2> 0 T1, T3T1, T3 are still conducting reactive current
id = iT1 = iT3 = ipk> 0, ud< 0.
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 ..
2.2.3 Rectifier voltage and current
• Average value rectifier voltage:
(2.11)
• Average current across load:
(2.12)
• Average value of current through thyristor:
(2.13)
• Maximum locking and reverse pressure applied to the component: Um
2.2.4 Coincidence phenomenon
Phenomenon is the state insect branches led thyristor in the same group at the
same conductive switches.

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Figure 2. 3: The phenomenon of 1-phase bridge rectification coincidence.

Figure 2. 4: Wave form graph when conduction occurs
Suppose T1, T3 are open to flow iT1=iT3=Id. WhenPulse openT2, T4. Because there
are L =>iT1, iT3 does not drop suddenly to 0 and line iT2, iT4 does not a sudden increase
from 0 Id. At this time, all 4 valves are open to prevent flow, the load 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 and
thus 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 the
thyristor 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 on
the thyristor. Diagram of pulse generation - controller:

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

synchronized
Th
compare

amplification

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

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

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 = Umcos
Comparative voltageuss = Uc - Udb.
When Uc = Udb uss = 0 is the time of comparison creating control pulse.
When => Uc = Udb =Umcos
Control angle
Rectifier voltage:

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

CHAPTER 3: DESIGN AND SELECTION OF DYNAMIC COMPONENTS
3.1
Introduction
3.1.1 Dynamic circuit

transformer

rectifier devices

filter

Figure 3. 1: Dynamic circuit block diagram
3.1.2 Function
Transformer:
• Convert the voltage of the AC grid to voltage suitable for the load.
• Change the number of phases of the grid source (1,2,3,6,12,… phase).
• Isolate from grid voltage.
Rectifier devices:The semiconductor valves (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 can
withstand.

Reverse voltage on the valve:
(3.1)
1-phase bridge rectifier we have:
(3.2)
In the calculation we have to calculate such that Ud is at maximum, cos.
: Reverse voltage coefficient.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

: Circuit voltage coefficient.
: Average voltage rectifier.
: AC source voltage.
(3.3)
Valve working current:
(3.4)
(3.5)
: Effective current through the valve
: Effective coefficient for 1-phase bridge diagram
: load current
(3.6)
The reverse voltage of the valve is to be selected:
(3.7)
With: Is the reserved voltage reserve factor
The effective current of the valve is to be selected:
(3.8)
: Is the reserve factor for the selected current
There are the following figures:

• Valve reverse voltage:
• Maximum working current:
• Control pulse current:
• Control pulse voltage:
• Maximum voltage drop on thyristor in conductive state:
• Leakage current:
• Speed of voltage variation
• Time switching:
• Permitted working temperature:
• Peak current pulse:
• Maintenance current:
3.2.2 Calculation of rectifier transformers
3.2.2.1 Rectifier voltage on load
(3.9)
In which:
= 10o: storage angle when there is a drop in the network voltage
voltage drop on thyristor.
voltage drop on connection line.
voltage drop across the transformer resistance and resistance.Preliminary
selection is about (5 - 10)%.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

(3.10)
=239
3.2.2.2 Maximum capacity of the load
(3.11)

3.2.2.3Apparent Capacity of the MBA
(3.12)
Power factor according to the 1-phase bridge scheme.
Load capacity at maximum.
3.2.2.4Preliminary calculation of magnetic circuits
cylindrical cross-section of transformer steel core:
(3.13)
kQ: The coefficient depends on the cooling method. (kQ = 6 dry transformer)
m: the number of phases of the transformer.
f: frequency.
3.2.2.5Transformer winding calculation
Primary winding voltage:
Secondary coil voltage:
The number of turns per coil is calculated:
(3.14)
Inside:
W: number of turns to be calculated.
U: coil voltage to be calculated.
B: sympathy (usually choose between 1T ÷ 1.8T). Choose B = 1 (T)
Number of primary coil turns:
Number of secondary coil turns:
The currents of the coils:

3.2.2.6Calculate the cross-section of the wire
(3.15)
Inside:
I: current flows through the coil.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

J: current density in the transformer, usually selected 2 2,75 ()
Choose J = 2,75 ()
The section of the primary winding:
Diameter of primary winding:
Cross section of secondary coil winding:
Diameter of secondary coil winding:
3.2.3 Filter design
Function: To limit the ac component of rectifier voltage to reduce undulating
current and load voltage.
We choose the LC filter:

Firgure 3. 2: LC filter circuit diagram
Components passed through the curved load of AC components are all filtered
in the filtration stage.
Beating factor of rectifier voltage q: quality assessment at 1 measuring point.
(3.16)
The pulse coefficient of the rectifier voltage depends on the number of pulses p
and the control angle α, q is best when α = 0 (Valve diode)
Leveling coefficient: evaluate the efficiency of the filtration stage.
(3.17)
Assume that the DC drop on the filter is negligible:
(3.18)
(3.19)
The higher the coefficient ksb is 1, the better we chooseksb = 11.
Choose Cf =100 and Lf = 300 mH

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

3.3

Conclusion
Because the calculation method has a formula so that the index of resistance is
easy to choose, while capacitors with inductors have only a fixed index, so we choose
capacitors, and the resistance to change easily
Through the calculation results above we choose: Thysristor S7412M

From: />Select a transformer with the following parameters:
U1 = 220 V; U2 = 265,56 V; W1 = 132 ; W2 = 159 ; I1 = 35,73 A;
S = 7879,6VA; d1 = 4 mm; d2 = 3,7 mm.
Select LC filter with parameter: L = 300 mH, C = 100.

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I2 = 29,6 A;


Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

CHAPTER 4: DESIGN OF CONTROL NETWORK PART
4.1
General introduction
4.1.1 Thyristor control block diagram

synchronized
Th
compare

amplification

Figure 4. 1: Thyristor control block diagram.
The phase of the copper phase is responsible for generating the same voltage as
URC (usually linear jagged voltage) that coincides with the voltage of the Thyristor.
The comparison stage is responsible for comparing the same voltage with the
control voltage Udk, finding the moment when these two voltages are equal, then
generate pulses at the output and send to the amplifier stage.
The pulse generator is responsible for creating a suitable pulse to open the
Thyristor.Thyristor pulses to open are required: front slope is vertical, to ensure
Thyristor open immediately when there is control pulse (usually this pulse type is
needle pulse or rectangular pulse);enough width with pulse width greater than the
Thyristor opening time, enough capacity, isolating the control circuit from the dynamic
circuit (if the dynamic voltage is too large).
4.1.2 Requirements of the control circuit
The control circuit is a very important step in the thyristor converter because it
plays an important role in determining the quality and reliability of the converter
door.The control circuit door requirement can be summarized in the following six
main points:
• Width of control pulse
• Loudness control pulse
• Requirements for tooth slope
• Symmetry of pulses in control channels
• Requirements for reliability: Control channel resistance must be small so that
the Thyristor will not open automatically when the leakage current

increases.Control pulses are less dependent on temperature fluctuations, source
voltage fluctuations.It is necessary to eliminate inductive noise to avoid
mistaken opening.
• Assembly and commissioning requirements: Replacement equipment for
assembly and adjustment, each with a high ability to work independently..
4.1.3 Control circuit duties
Is to generate pulses at the desired times to open the dynamic valves of the
rectifier.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

The function of the control circuit:
• Adjustable control pulse position within a positive half cycle of voltage applied
on thyristor cathode - cathode.
• Generate pulses open thyristor pulse width tx <10μs. Pulse width expression:
(4.1)
Idt: maintained current of thyristor.
: growth rate of the load current.
The joystick object characterized by the control quantity is angle α
4.1.4 Control principles
Thyristor control circuits can be classified in several ways. But the control
circuits are based on the principle of changing the phase angle and according to which
we have two principles of horizontal and vertical control.
Horizontal override is a method of creating the angle α to change by shifting
the voltage to a sinusoid in the horizontal way relative to the quasi voltage.The
disadvantage of this method is that the angle α depends on the voltage form and grid
frequency, so the accuracy of the control angle is low.

Vertical override is a method of creating the angle α to change by shifting the
dominant voltage in the vertical method compared to the quasi voltage.This method
has high precision and wide control range (0 ÷ 180)
There are 2 vertical control methods: linear and arccos. We choose the linear
vertical control method.
4.2
Principles of operation from zone
4.2.1 Copper phase stitching
Principle of operation:
At OPAMP A1:
In the positive half cycle: U+(A1)> U-(A1) UB> 0
During the negative half cycle: U+(A1)< U-(A1) UB< 0
At OPAMP A2:
When UB> 0 => T1 close U-(A2)> U+(A2). We consider the integral circuit
included: rheostatR3,capacitor C1, and OPAMP A2at that timeUđb = UC =
Because UB = const linear function.
When UB< 0 => T1 open UB< U-(A2), diode D1 close. U-(A2) = UC1 = 0
There is increased current through the capacitorThe voltage at UC is negative to
balance the voltage to 0

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

4.2.2 The stage of comparison

Figure 4. 1: Circuit diagram of comparison stitching.
Working Principle:

Choose
At OPAMP A3 => U-(A3) = ; U+(A3) = 0
When URC + Uđk> 0 U-(A3) > U+(A3) UD = Vcc
WhenURC + Uđk< 0 U-(A3) < U+(A3) UD = Vcc

Figure 4. 2: Waveform diagram
4.2.3 Stitch creating beam pulse
For a circuit diagram, in order to reduce the power current for the amplifier
stage and increase the number of open pulses, in order to ensure the thyristor is open
reliably, it is common to generate beam pulses for the thyristors.The principle of
pulsed pulse is that before entering the amplifier stage, we insert an AND gate with the
input signal received from the comparator stage and from the beam pulse generator as
shown.
compare
beam pulse

amplification

Figure 4. 3: Schematic of the beam pulse generation.

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

Figure 4. 4: Schematic diagram of pulsed pulse generator using algorithm
amplifier.
• Working Principle:
Assume at first outputUE = VccU+(A4) . At this time, capacitor C is loaded in the

direction from the output through R8 to GND, the more capacitor voltage is charged
on the capacitor, until the voltage across the capacitor is equal to UC = U-(A4) > U+(A4)
= then the UE will change to the saturation level UE = VccU+(A4) .At this time,
capacitor C will discharge in the opposite direction, the port capacitor discharge
voltage across the capacitor decreases, until UC = U-(A4) < U+(A4) . Capacitor C will
start to charge again, the continuous charging and discharging process alternately
creates a UE multivibrator pulse.
4.2.4 Amplifier stitching

Figure 4.5: Amplifier stitching circuit diagram.
With the task of generating a suitable pulse to open the thyristor as mentioned
above, the final amplifier stage is usually designed with a power transistor as
shown.To have a needle pulse sent to the thyristor, we use a pulse transformer (BAX),
to be able to amplify the power we use transistors , diode and to protect and the
primary winding BAX when locks suddenly.
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

In fact the control pulse only needs a small width (about 10 ÷ 200 μs), but the
opening time of the power transistors is long (up to a half cycle of 0.01s), causing the
excess heat of the transistortoo large and the BAX primary winding size is large.In
order to reduce the radiant capacity and the size of the BAX primary wire, you can
add a cascade capacitor C3.According to this diagram, is only open for current to flow
during the charging time, so their effective current is much smaller.
4.2.5 Control circuit diagram

Figure 4.6: Thyristor control circuit diagram.

Figure 4.7: Diagram of control circuit curves.

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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

4.3

Contributing circuit parameters
Control circuit is calculated from the request to open Thyristor, so we have
basic parameters to calculate the control circuit:
• Thyristor control voltage: = 3 V
• Thyristor control current: = = 0,18 A
• Thyristor opening time: = 10 s
• Width of control pulse: = 20s
• Frequency control pulse: = kHz
• The loss of symmetry allows: =
• Voltage control circuit: U = 12V
• Pulse amplitude drop: = 0,15
4.3.1 Pulse transformer calculation
Select the core material is ferrite ferrite HM, the core has a toroidal shape that
works on a part of the magnetization properties with ∆B = 0.3T, ∆H = 30A / m without
air clearance..
• Transformer ratio: choose m = 3
• The secondary voltage of the pulse transformer The secondary voltage of
the pulse transformer: = = 3 V
• The voltage applied to the transformer voltage transformer secondary

winding: = m = = 9V
• Current level voltage of pulse transformer: = = 0,18A
• The primary current of the pulse transformer: = = = 0,06A
4.3.2 Calculate the final amplification stage
Select 2SC911 Power Tranzitor Type NPN transistor is silicon semiconductor.
• Voltage between Collector and Bazo when Emitter open circuit: = 40V
• Voltage between Emitter and Bazo when Collector open circuit: = 4V
• The maximum current the Collector could endure: = 500 mA
• Power dissipation in Collector: = 1,7 W
• The maximum temperature of the junction surface: =
• Gain factor:
• Collector max current: IC3max = 0,5 A
• Collector's working current:
• Base working current: = = 1,2 mA
We see that with selected Thyristor type has quite small control capacity: = 3 V,
= 0,18 A.
Therefore, we only need one amplifier stage to control the Tranzitor.
Select the power source for the pulse transformer E = 15 V, with the source E =
15 V we must add resistor in series with the Emitter pole of T3.IC3 = I1 IE
All the Diode in the control circuit use type 1N4009 with parameters:
• Electricquota
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Topic: Design of a Single-phase controlled bridge rectifier to control speed of a
separately excited DC motor

• Maximum reverse voltage
• Diode voltage for open through
4.3.3 Calculation of beam pulse generator selection

Each control channel must use 4 algorithm amplifiers, so we choose 4 IC type
TL084 by TexasInstrument, each of these ICs has 4 op amps.

Figure 4.8: sewing beam pulse
Parameter
• Power supply voltage: choose Vcc =
• The voltage difference between the two inputs:
• Working temperature: T = 25
• Power Consumption: P = 0.68 W
• Input impedance:
• Output current:
• Input current:
• Allowable speed of voltage variation: )
The beam pulse generator circuit has frequency f,or beam pulse period:

We have period of oscillation:
Choose R6 =R7= 33 k thỡ T = 2ìR8ìC2ìln3 =40 às.
We have: R8ìC2=18,2 às.
Choose C2=0,01 µF =>R8= 1820 Ω
For the convenience of the circuit, we choose R8 as a 2kΩ resistor.
4.3.4 Compute choosing the comparison layer
Each control channel has an algorithm amplifier acting as a comparison layer,
we choose IC type TL084 as above.
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