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**PART 1 VARIABLE SPEED DRIVE IN PUMPING STATIONS: ADVANTAGES **

PART 2 SPEED CONTROL IN INDUCTION MOTORS

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

1 PART 1

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

SUMMARY – PART 1 Introduction Criteria for the selection of the Variable Speed Drives Energy saving in pumps and fans with Variable Speed Drives 3.1 Typical pump and fan curves 3.2 Movement of the pump curve in accordance with the speed drop 3.3 Movement of the power and efficiency curves in accordance with the speed drop 3.4 Basic relationships for the power control 3.5 Efficiency of pumps with VSD Methods for flow control Needed information for a correct consulting in the energy saving field

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**Variable Speed Drives in Pumping Stations INTRODUCTION**

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

1. INTRODUCTION Power Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields. As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company.

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**Variable Speed Drives in Pumping Stations CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE**

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

2. CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE Input Filters Input Chokes Protection Degree Ambient Temperature Constant and Variable Torque VSD? VSD Applications Technical Assistance [ SHOW ] [ SHOW ] [ SHOW ] [ SHOW ] [ SHOW ] [ SHOW ] [ SHOW ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

A. INPUT FILTERS WHAT IS ELECTROMAGNETIC COMPATIBILITY? It is a concept linked to any electronic device. This concept means the ability of a device to avoid the generation of interferences above a defined dB level. It means the measure of its immunity versus a defined dB level. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

A. INPUT FILTERS WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD? [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

A. INPUT FILTERS RFI EMISSION SOURCES IN A VSD The RFI can be radiated and conduced. The conduction can be produced through the Motor Cables, through the Power Supply Cables and through the Earth Connections. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

A. INPUT FILTERS Vcc = Ve · 1,41 = 380 · 1,41 = 534 = 500 · 1,41 = 720 = 690 · 1,41 = 972,9 CABLE LENGTH 40 meters of screened cable. 150 meters of screened cable. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

B. INPUT CHOKES USE OF INPUT CHOKES FOR HARMONIC REDUCTION. Power electronics for SD700 series: 90A – 170A. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

B. INPUT CHOKES USE OF INPUT CHOKES FOR HARMONIC REDUCTION. Power electronics for SD700 series: 210A – 2200A. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

C. PROTECTION DEGREE PROTECTION DEGREE FOR EXTRA PROTECTION IP54 protection impedes that dust or any other particles damage the devices. In this case, splashing occurred near the motor don’t damage our products. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

D. AMBIENT TEMPERATURE OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES Operation current at 45º Overload peak for 1 sec. Overload for 30 sec. at 50º Operation current at 40º Operation current at 50º Overload for 60 sec. at 40º [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

D. AMBIENT TEMPERATURE ENVIRONMENTAL TEMPERATURE Power Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions. They CAN RESIST TILL 50ºC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE. [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

E. CONSTANT TORQUE AND VARIABLE TORQUE THERMAL SHOT (85ºC) THERMAL SHOT (85ºC) OVERLOAD 1.1In (40ºC) Temperature 80ºC OVERLOAD 1.25 In (40ºC) VARIABLE TORQUE Temperature 70ºC VARIABLE TORQUE 15 kw 15 kw OVERLOAD 1.5In (40ºC) OVERLOAD 1.5In (50ºC) Temperature 60ºC Temperature 60ºC CONSTANT TORQUE CONSTANT TORQUE 11 kw 11 kw Competitors Power Electronics [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

E. CONSTANT TORQUE AND VARIABLE TORQUE POWER AT CONSTANT TORQUE POWER AT VARIABLE TORQUE P.V.P MODEL A 11 15 100 MODEL B 18,5 115 [ BACK TO THE CRITERIA ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

F. VARIABLE SPEED DRIVE APPLICATIONS CONTROL The Variable Speed Drives extend the regulation field with regard to: Flow fluctuation Pressure control Temperature control Level control… APPLICATIONS Several applications can be considered: Pumping stations Pressure groups Irrigation systems High concentration of carbonic monoxide, oxygen… Heating and Air conditioning… [ BACK TO THE CRITERIA ]

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**Variable Speed Drives in Pumping Stations ENERGY SAVING IN PUMPS AND FANS**

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

3. ENERGY SAVING IN PUMPS AND FANS WITH VSD 3.1 TYPICAL PUMPS AND FANS CURVES. HEIGHT, POWER AND EFFICIENCY H (m) FLOW

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

3. ENERGY SAVING IN PUMPS AND FANS WITH VSD 3.2 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP. H 16 14 12 10 8 6 4 2 nnom 0.8 n nom 0.7 n nom 0.9 n nom Q (l/s)

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

3. ENERGY SAVING IN PUMPS AND FANS WITH VSD 3.3 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP. p Q Power Efficiency

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

3. ENERGY SAVING IN PUMPS AND FANS WITH VSD 3.4 BASIC RELATIONSHIPS FOR THE POWER CONTROL. POWER (W) = r x g x H x Q x ŋ-1 r = Density (Kg/m³) g = Gravity (9.81m/s²) H = Height (m) Q = Flow (m³/s) ŋ = Efficiency

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

3. ENERGY SAVING IN PUMPS AND FANS WITH VSD 3.5 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE. 50% 60% 70% 80% 85% 88% 87% 30% 1 X n 0.9 X n 0.8 X n 0.7 X n 0.6 X n 0.5 X n 0.4 X n 80 70 60 50 40 30 20 10 N = 1480 RPM Efficiency curves Curves H – Q System curves Q flow m3/min

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**Variable Speed Drives in Pumping Stations METHODS FOR FLOW CONTROL**

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL Valve Control By – Pass Control Start – Stop Control (On / Off) Variable Speed Drive [ SHOW ] [ SHOW ] [ SHOW ] [ SHOW ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL A. VALVE CONTROL. CHARACTERISTICS. Pumps always work at maximum speed. The transversal section of the conduct or pipe. Pressure increases when pipe cross section is reduced. Problems with the over-heating of the fluids. Cavitation, turbulences. [ BACK TO THE LIST ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL A. VALVE CONTROL. GRAPHIC. Height in m H2O 80 STATIC height 20 meters FLOW 1 X n 0.9 X n 0.8 X n 0.7 X n 0.6 X n 0.5 X n 0.4 X n 90% 100% 70% 50% 80% 60% 70 60 50 40 30 20 n = 1480 RPM Efficiency curves 10 H-Q curves System curves 10 20 30 40 Q Flow m3/min 50% Flow 100% Flow

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL A. VALVE CONTROL. GRAPHIC. BOTTLENECK INCREASES H 3 2 HEIGHT 1 OPERATIONAL POINT WITHOUT BOTTLENECK Q KW 7 POWER Q FLOW

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL B. BY - PASS CONTROL. Q FLOW BY-PASS EFFECT HEIGHT H OPERATIONAL POINT WITHOUT BY-PASS POWER KW System curves Pump H – Q curves Efficiency curves This is the least efficient method with regard to the energy consumption. The pump always works at maximum power without taking into account the flow level. [ BACK TO THE LIST ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL C. START – STOP CONTROL (On / Off). CHARACTERISTICS. It is recommendable for those systems in which the pumping flow is constant. It leads to mechanical and electrical stress. It does not allow to maintain constant parameters, a small or big variation always exists. Over-pressure during the starting. Water hammering during the stop. [ BACK TO THE LIST ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE CONTROL. CHARACTERISTICS. It allows to keep constant those parameters to be controlled. It provides a reduction of absorbed power by the motor. Compensation of reactive power of the motor. Reduction of mechanical and electrical failures. Reduction of civil construction cost in pumping systems. [ BACK TO THE LIST ]

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE CONTROL. GRAPHIC. STATIC height 20 meters Height in m H2O n = 1480 RPM Efficiency curves H – P curves System curves 10 20 30 40 Q Flow m3/min 70 60 50 80 490 kPa 637 kPa REFERENCE 1 X n 0.9 X n 0.8 X n 0.7 X n 0.6 X n 0.5 X n 0.4 X n 1400 RPM PID

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE CONTROL. TABLE. SPEED DROP 9 8 Q HEIGHT H OPERATIONAL POINT AT FULL LOAD 7 FLOW POWER KW

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE CONTROL. ENERGY MISUSE. POWER LOSSES HEIGHT VALVES SYSTEM FREQUENCY CONVERTER REDUCED SPEED MISUSED POWER USEFUL POWER STATIC HEIGHT SET POINT

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE CONTROL. COMPARATIVE CURVES AND POWER REQUIREMENTS. FLOW (%) POWER (%) A: Control using Variable Speed Drive. B: Control using valve adjusting.

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

4. METHODS FOR FLOW CONTROL D. VARIABLE SPEED DRIVE IN WELLS. SUMMER WINTER

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Variable Speed Drives in Pumping Stations NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD 5

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

5. NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD ANALYSIS OF EXISTING SYSTEMS A. Type of control B. Height curves and flow of the system PUMP OR FAN DATA A. Pump and fans efficiency curves B. Fan or pump power C. Motor curves PROCESS INFORMATION A. Fluid or gas density B. Flows and required duty cycles C. Static and dynamic height values

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**Variable Speed Drive in Pumping Stations ADVANTAGES**

5. NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD IF WE DO NOT HAVE COMPLETE INFORMATION, THE FOLLOWING DATA COULD BE USEFUL HEIGHT / FLOW CURVES OR CHARACTERISTICS OF THE SYSTEM REQUIRED FLOWS AND OPERATION CYCLES FLUID OR GAS DENSITIES VALUES OF STATIC AND DYNAMIC HEIGHT PUMP OR FAN POWER MINIMUM INFORMATION REQUIRED (GRAPHICS USE) REQUIRED FLOWS AND OPERATION CYCLES PUMP OR FAN POWER (DIFFERENT FLOWS)

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

2 PART 2

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**Speed Control in Induction Motors INTRODUCTION**

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

SUMMARY – PART 2 Introduction Induction motors Control Outlines Speed control in a Squirrel Cage Motor Electronic Outlines for A.C. Motor Control

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**Power Electronics technology and experience in power electronics **

Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS 1. INTRODUCTION Induction motor control outlines: variable speed drive and softstarters Power Electronics technology and experience in power electronics Basic Outlines: To know the outlines of the induction motors Variable speed drives performance Softstarters performance Harmonics in industrial provisions Electromagnetic compatibility of VSD Energy saving in pumps and fans Applications and control

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**Speed Control in Induction Motors INDUCTION MOTORS CONTROL OUTLINES**

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

2. INDUCTION MOTORS CONTROL OUTLINES INDUCTION MOTORS The induction motor (asynchronous or squirrel cage), is made up of two main parts: The ROTOR , fixed along an axis The STATOR

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

2. INDUCTION MOTORS CONTROL OUTLINES INDUCTION MOTORS The rotor is built with electronically short-circuit bars through rings at the edges, which form the squirrel cage

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

2. INDUCTION MOTORS CONTROL OUTLINES INDUCTION MOTORS Connecting the motor to a 3-phase power supply, a rotational magnetic field it is generated in the stator (flux). This is due to: The physical position of the stator windings: 3 coils separated physically 120º. The current in those windings diphase 120º electrically.

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

2. INDUCTION MOTORS CONTROL OUTLINES INDUCTION MOTORS The flux lines (arrows) induce currents on the rotor bars. When a magnetic field acts over a conductor in which a current flow, the resultant is a force which produce the torque and therefore the motor rotation. ROTATING FIELD

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**Speed Control in Induction Motors SPEED CONTROL IN A SQUIRREL CAGE MOTOR**

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

3. SPEED CONTROL IN A SQUIRREL CAGE MOTOR SPEED CONTROL A squirrel cage motor is a constant speed motor. But speed can be controlled acting on the number of poles of the motor and the frequency supply. TORQUE – SPEED RELATIONSHIP MOTOR CURRENT MOTOR SPEED STARTING NO LOAD CURRENT MOTOR TORQUE MAXIMUM STARTING MOTOR SPEED » Torque – Speed curve in a induction motor » Current – Speed curve

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

3. SPEED CONTROL IN A SQUIRREL CAGE MOTOR SPEED CONTROL Method used by electronic speed controllers To vary the frequency supply of the motor. WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD? A high performance in the whole range of speeds is obtained This method disposes of a continuous variation of the speed, that might be electrically through control signals such as 0-10VDC o 4-20mA. This makes VSD for A.C. motors to be the best option for process automation. The available motor torque is constant even at low speeds. This offers the possibility to work with any load. It is possible to work with frequencies above 50Hz.

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**Speed Control in Induction Motors ELECTRONIC OUTLINES FOR A. C**

Speed Control in Induction Motors ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL 4

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL FREQUENCY SUPPLY VARIATION Torque – speed curve evolution when the frequency supply varies. % OF NOMINAL TORQUE MOTOR SPEED » Torque – Speed curve

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL WHY V/Hz CONSTANT? Equivalent circuit per phase can be represented according to: IR: Component of load. “Real” component that flows through the rotor. This current generates the torque and therefore increases as the load of the motor increases. IM: “Imaginary” component, 90º diphased regarding to the “real” component. Magnetizing current responsible of the motor flux. It is convenient to keep it constant as the load varies.

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL WHY V/Hz CONSTANT? Vector diagram of the motor current. Real current (Torque) Total Current IT Imaginary current (Magnetizing) cos = Power factor » At full load » At medium load Magnetizing current IM is constant regardless of the load. It is this current which generates the magnetic field in the stator, affecting to the motor capacity of producing torque.

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL WHY V/Hz CONSTANT? Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux. E1 = Supply voltage f = Supply frequency LS = Magnetizing inductance of the stator In a electronic speed controller, the motor voltage supply must be adjusted proportionally to the frequency, so that the magnetization current remains constant. Increasing the motor speed, the slip (S) decreases and the relative frequency decreases too. Then the cosR improves, the losses inductance is reduced and e Ir decreases.

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL RELATIONSHIP VOLTAGE – FREQUENCY IN A VSD. VOLTAGE COMPENSATION AT REDUCED SPEEDS Voltage increase. It is necessary when the load requires a high starting torque (transport bands, high inertia load, …). 100% OUTPUT VOLTAGE 50Hz OUTPUT FREQUENCY AREA WHERE THE MAGNETIC FIELD MAKES WEAKER 100% OUTPUT VOLTAGE 50Hz OUTPUT FREQUENCY STARTING VOLTAGE » Voltage – Frequency relationship in the drive » Voltage compensation at reduced speeds

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL INVERTER CIRCUIT Output waveforms of the inverter bridge

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE » Output voltage (quasi-rectangular wave) Transistor current Free flow current » Output motor current

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL MODULATION AND WAVE SHAPES. OUTPUT VOLTAGE CARRIER WAVE SINUSOIDAL WAVE REFERENCE SIGNAL SUPERIOR TRANSISTOR ON INFERIOR TRANSISTOR ON INVERTER OUTPUT VOLTAGE (REGARDING TO THE MIDDLE POINT IN THE DC BUS) OUTPUT VOLTAGE BETWEEN PHASES PWM » Modulation and waveforms of the output voltage

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL OUTPUT WAVES MODULATION NOMINAL FREQUENCY – NOMINAL VOLTAGE MEDIUM LEVEL FREQUENCY – MEDIUM LEVEL VOLTAGE A triangular signal is compared to a senoidal one in the sinusoidal modulation. The wave shape of the current produced in the motor is very similar to the senoidal one, with a very long distortion. » Output voltage modulation

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL OUTPUT WAVES MODULATION NOMINAL FREQUENCY – NOMINAL VOLTAGE MEDIUM LEVEL FREQUENCY – MEDIUM LEVEL VOLTAGE The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes. New technology: vector space modulation better wave shapes and less commutations. » Output voltage modulation

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL VECTOR SPACE MODULATION A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors). VC N VA VE Rotation speed (rev/sec) Frequency Instantaneous position Status in a cycle Vector length Voltage amplitude » 3-Phase vector

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION Small content of harmonics in the motor Small pulsate pairs Constant frequency modulation Better use of voltage supply Adapted to the wave generation using microprocessor

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL ELECTRONIC DEVICES BASED ON COMMUTATION THYRISTORS Power semiconductor with PNPN structure. Currently not used. BIPOLAR TRANSISTORS Based on NPN or PNP structure. ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation; control realized by mean of voltage, the commutation is done by the application of voltage to the gate. Advantages of the IGBT: Less voltage saturation Higher commutation frequencies Higher overload capability Less power demand in the motor circuit

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL ELECTRONIC CONTROL THE BRAIN OF THE DRIVE Functioning: It receives the required speed signal. It receives user commands: stop, start…etc. It generates waveforms modulated in vector space technology. It commutates the switches. It controls the current in the motor to protect the drive and the motor from overloads. It allows to do the necessary adjustments for one application: acceleration and deceleration ramps, maximum and minimum speed…etc. It offers output information: motor current, frequency, start, stop, failure indication…etc.

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL MONOPHASIC DEVICES WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS Small motors are designed with windings of 230Vac. Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor. Drive with single-phase input of 230Vac. » Wiring connections for 230/400V motors

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL REGENERATION Current operation Motor operation Generator operation 2 1 -1 Generator torque Motor Torque N2 N1 speed slip +ve -ve torque

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL LOADS TYPES. CONSIDERATIONS Before choosing the size of the motor and VSD, it is necessary to understand the torque-speed characteristics for every single load. 100% Motor speed Constant Torque Constant Power TORQUE POWER 200% 50% Magnetic field makes weaker Available TORQUE peak POWER TORQUE Motor speed 50Hz 100Hz 100% 200% 63% Continuous Torque (limited due to the motor cooling) » Relation (%) between torque and power » Torque loss due to motor cooling

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL BASIC LOADS TYPES Constant power load The torque required by the load increases as the speed decreases. Constant power (mills, winding machines) Constant load torque Constant torque at any speed (transport bands, presses of printers, crane and hoist, …etc) Required resistant torque Continuous torque TORQUE Area for intermittent operation Area for continuous operation Available torque peak TORQUE Area for intermittent operation Area for continuous operation Continuous torque Required resistant torque Available torque peak » Load at constant power » Load at constant torque

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**Speed Control in Induction Motors VARIABLE SPEED DRIVE & SOFTSTARTERS**

4. ELECTRONIC OUTLINES FOR A.C. MOTOR CONTROL TORQUE – SPEED RELATIONSHIP Available torque peak Area of intermittent operation Area of continuous operation TORQUE Continuous torque Resistant torque required Speed Resistant torque required TORQUE Available torque peak Area of intermittent operation Area of continuous operation Continuous torque Speed » Torque proportional to the Speed » Torque proportional to the Square of the Speed

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**Thanks for your attention**

Presentation Variable Speed Drives in Pumping Systems: Advantages Speed Control in Induction Motors Realization Pilar Navarro Organization Marketing Department ©2006 Power Electronics España, S.L.

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