Home

USER`S MANUAL

1. Where cosq power factor m transformation ratio T efficiency b plot P f E and y f E c Why do we use a step up transformer Show that a 500 winding coil is enough to supply the induction cooker from mains 230 V 50 Hz 96 d How does an induction cooker work e Deal with the resistance of the secondary 5 Lets see how does the induction cooker work as a function of the output frequency Fill the following cells f Hz 0 50 100 150 200 250 L A P W 6 Deal with your results 7 Use delayed or PWM command Compare both commands delay angle a or b angles 8 Give the electrical model for the induction cooker a How can we obtain sine wave current electronic component b What is this physical phenomenon 97 EMERGENCY POWER SUPPLY I Introduction Voltage source inverter can be used as emergency power supply in many fields like computer systems If a default appears on the line the inverter is designed to supply computers or network systems with 230 V 50 Hz for example Then work in progress or data can be saved II Scheme Inverter bench CO 120 used as emergency power supply DC link batteries 24 V Converter bench CO 100 used as charger Load 24 V 40 W bulb 98 1 Charger Refer to laboratory work n 3 active load of the CO 100 pedagogical 2 Inverter Refer to full brid
2. 56 A Square wave command I Power switches a Select square wave command a Adjust f 50 Hz a Enter 1 Visualize simultaneously command signals of T1 and T2 2 Plot command signals diagram and give closed devices a R L C Load is connected All strap wires are plugged D a DC power supplies are connected El E2 E 12 V The bench is turned on D JI Waveforms gt DC link Visualize and plot 1 t and igs t gt Inverter 1 Visualize simultaneously Vps and Vps2 2 Visualize simultaneously Vp and Vp 3 Visualize and plot simultaneously ir and irz currents into T1 and T2 57 4 Visualize and plot ipi and ip gt Load 1 Visualize an plot output voltage 2 Visualize and plot output current II Analysis Both transistors are complementary as follows closed devices sas O T 2 1 Deal with R L C load about output current and command signals waveforms 2 Adjust L to obtain no phaseshift between output voltage and output current Output current should become sine wave or quasi sine wave What is that phenomenon 3 Check output frequency fo and compare it with theoretical expression 4 Deal with f lt fo and f gt fo Note give closed devices for each switching step give net power sign for each switching step 58 HI Measurements Fill the following cells LOAD c Uc Da ic Ic I f fo scope AC
3. point C point D NON INV INV NON INV INV A is grounded Vos Voi Vp4 Vps4 B is grounded Vps2 Vp2 Vp3 Vps 3 4 1 2 Visualize iri 172 175 and 174 currents into T1 T2 T3 and T4 Visualize ipi Ipo 1p3 and ip currents into D1 D2 D3 and D4 Load Visualize and plot the output voltage Visualize and plot the output current 88 II Analysis Both transistors are complementary as follows O T 2 closed devices T4 T w T 5 Deal with the R L C load about the output current and command signals waveforms 6 Adjust L to obtain no phaseshift between output voltage and output current Output current should become sine wave or quasi sine wave What is that phenomenon 7 Measure output current frequency fo Derive fo 8 Deal with f lt fo and f gt fo Note give closed devices for each switching step give net power sign for each switching step III Measurements Fill the following cells LOAD c Uc Uc ic Ic I f fo Scope AC DC DC VALUES 89 IV Spectrum analysis E 24 V et f 50 Hz a f 210Hz a C 2 2 uF L 0 25 H resonance is reached 1 Give the quality factor Q Loo Rr where Ry is the total resistance of the circuit 2 Give the value of the load when resonance is reached What about the load impedance before and after resonance 3 The Fourier series of the output voltage is given as u
4. Measurements Fill the following cells LOAD Uc Uc U lt ic Ic D scope AC pc DC VALUE 53 IV Spectrum analysis Fourier series of output voltage is given as u t BE sin ot ssin 36D Esino Jt 1 Visualize and plot output current current probe 2 Give harmonics decomposition of output current from u t What about harmonics level 3 What kind of load R L association can simulate 4 Give fundamental expression i t of i t as a function of E L o and phaseshift 5 Then give RMS expression I of it Compare it with spectrum analysis 54 B Bipolar PWM a Select bipolar PM mode with 17 a Adjust parameters as follows f 50 Hz a 35 and b 0 a Enter gt Single angle E 12 V f 50 Hz a 20 and b 0 1 Visualize and plot command signals output signals and realize spectrum analysis 2 Plot switching command diagrams and explain the behaviour of such configuration gt Two angles Repeat previous actions with following parameters E 24 V f 50 Hz a 24 and b 34 Note give closed devices for each switching step give net power sign for each switching step 55 RESONANT LOAD Scheme DC link DC power supply current reversible Imax 3 A Load rheostat 10 Q 5 7 A or 33 Q 3 1 A in series with an iron core coil L 10 Q 0 1 H 1 4 H and a capacitor C 22 uF
5. 38 20 10 EE m m aor H m 1 11 12 13 14 15 16 17 18 19 third and fifth harmonics are vanished 37 Note a and b values can be read directly on the screen of the scope However cursors can be suitable if the scope is a digital one 38 LABORATORY WORK HALF BRIDGE VOLTAGE SOURCE INVERTER PANEL A 39 Single phase voltage source inverter can be classified into two types gt Inverter associated with a center tapped transformer A single DC power supply is required DC link gt Half bridge inverter leg inverter Two different DC links are required Note a DC link can be equally spilt into two if both capacitors have the same value G becomes the centre point 40 41 RESISTIVE LOAD a The Panel is set the bench is supplied rear side Scheme DC link DC power supply Imax 3 A Load rheostat 10 2 5 7 A or 33 Q 3 1 A a Setup every components 42 A Square wave command I Power switches a When the bench is turned on square wave mode and 100 Hz output frequency are displayed 1 Visualize and plot both T1 and T2 command signals respectively cm and Cm2 2 Measure and compare command signals frequency to the displayed frequency 3 Note that whatever the chosen frequency both signals remain complementary with each other II Waveforms Two strap wires are required C and Cy respec
6. The output voltage is not altered by the iron core coil Explain the reason why What about voltage losses due to rectifiers 2 Compare currents waveforms between inductive and resistive load 3 From previous waveforms deal with the inverter s behaviour Picture equivalent circuit for each switching step including current s path Note give closed devices for each switching step give net power sign for each switching step III Measurements Fill the following cells LOAD Uc Uc Uc Ic Scope AC DC DC l Q C VALUES 82 IV Spectrum analysis E 24 V et f 50 Hz Fourier series of the output voltage is given as u t 3E sin ot ssin 36D Esino Jt 1 Visualize and plot the spectrum analysis of the output current 2 Note that the harmonics level is reduced Explain thus the influence of the coil Which consequences may be induced when the load is an ac motor 3 The fundamental of 1 t is called i f t define i t as a function of E L o and phaseshift Give RMS expression I of trr Calculate Iir 83 B Delayed command I Waveforms DC link Visualize and plot the source output current ig t Inverter 1 Visualize Vps1 Vps2 Vps and Vpsa 2 Visualize Vp Vpo Vp3 and Vp4 gt Load 1 Visualize the output voltage 2 Visualize the output current III Analysis Transistors are complementary as follows closed de
7. a Same questions with the following parameters a 25 a 18 b 50 b 38 78 b Derive first five harmonics d What kind of electronic filter can be used in order to keep the fundamental part of u t Compare square wave command with unipolar PWM command 79 INDUCTIVE LOAD a The Panel B is set the bench is supplied rear side Scheme DC link DC power supply Imax 3 A Load rheostat R 10 Q 5 7 A or 33 Q 3 1 A in series with an iron core coil 10 Q 0 1 H 1 4 H a The R L load is plugged and all strap wires are set a The DC link is on a The bench is turned on adjust f up to 50 Hz and E up to 24 V 80 A Square wave command I Waveforms DClink Visualize and plot the source output current ig t gt Inverter Visualize and plot Vpsi Vps2 Vps3 and Vps4 2 Visualize and plot Vp Vp Vp and Vp4 The following table may be useful point C point D NOT INV INV NOT INV INV A is grounded Vpsi Vpi Vp4 Vps4 B is grounded Vps2 Vp Vps Vpss 3 Visualize ri 172 173 and ir currents into T1 T2 T3 and T4 4 Visualize ipi Ip 1p3 and ip currents into D1 D2 D3 and D4 gt Load 1 Visualize and plot the output voltage 2 Visualize and plot the output current 81 II Analysis Both transistors are complementary as follows O T 2 closed devices T4 T w T 1
8. 100 Hz The Fourier series of the output voltage is given as u t ae sin at sin 3at Esino n 45 1 Deal with the fact that only odd harmonics remain 2 What about the mean value Verify experimentally 3 Visualize the output voltage spectrum deal with the number of harmonics compare it with Fourier analysis 4 The fundamental is called u define u t as a function of E give RMS expression Uy of uj as a function of E Calculate Uj what kind of electronic filter can be used in order to select fundamental part of the output signal What are the main disadvantages with square wave command 46 B Bipolar PWM I Power switches a Select bipolar PWM with 17 adjust parameters as follows f 200 Hz a 35 and b 0 ENTER 1 Compare cy and cq 2 Verify f and a with the scope 3 Visualize and plot both T1 and T2 command signals cx and Cm2 a Adjust now f 100 Hz a 30 and b 45 1 Verify f a and b with the scope 2 Visualize and plot T1 and T2 command signals 3 What condition a and b must verify to reach bipolar PWM II Waveforms a Single angle PWM E 12V f 200 Hz a 35 and b 0 DClink Visualize and plot ig and i5 with a current probe Inverter 1 Visualize and plot simultaneously Vps and yps2 2 Visualize simultaneously ir and iz currents into T1 and T2 47 gt Load 1 Visualize and plot the output voltage 2 V
9. 2 A 330 Q 1 A 22 inductive load Ref PSYJR Iron core coil 0 1 H 1 4 H 10 Q 2 A battery lead 12 V 24 V Ref CO 106 single phase transformer primary 2x 12V secondary 230 V 100 VA induction motor Ref MO90 220 230 V 0 8 A 23 HI Safety and directions for use The following instructions must be respected by the user 1 Check the laboratory desk supply emergency stop switch warning lights 2 Lecturer must develop a step by step set of instructions on how to follow any experiment 3 Safety wires must be used only 4 mm Coloured wires are recommended Use strap wires when it is mentioned 4 Never operate inside the bench while it is powered 5 Respect maximal values Imax Power max X Caution Differential probe should be used in order to avoid any short circuits while waveforms are visualized the bench is grounded 6 Use batteries cautiously Short circuits may occur 24 IV Power components replacement This bench must stand horizontally and must not be exposed to moisture A Caution to prevent electrical shock hazard the bench must be turned off before any component replacement A Caution if one or many components are damaged it is recommended to check all of them even thoueh they appear undamaged A component tester may be useful All power components are plugged on connectors sold on printed circuit board 1 Transistor Unscrew the con
10. 40 and 60 derive uj t as a function of E thus derive Uj as a function of E calculate E 4 What kind of electronic filter can be used in order to keep the fundamental part of u t Compare square wave command with delayed command 71 C Bipolar PWM I Power switches a Select Bipolar PWM with 20 a Adjust parameters as follows f 150 Hz a 40 and b 0 a Enter 1 Measure the output frequency and visualize Cm1 Cm2 Cm3 Cm4 and a a Adjust new parameters as follows f 150 Hz a 30 and b 45 2 Measure the output frequency and visualize Cm1 Cm2 Cm3 a and b 3 Which values must verify a and b in order to reach bipolar PWM II Waveforms 1 Single angle PWM E 12V f 150 Hz a 40 and b 0 2 Two angles PWM E 12V f 150 Hz a 30 and b 45 gt DClink Visualize and plot the source output current ig t gt Inverter 1 Visualize simultaneously Vps and Vps4 INV 2 Visualize simultaneously Vps2 and Vps3 INV 3 Visualize iq 172 173 and ir4 currents into T1 T2 T3 and T4 72 gt Load 1 Visualize the output voltage 2 Visualize the output current III Analysis Transistors are complementary as follows closed devices T 2 Panel B T A T Ura 27 A 2n closed devices T T T T From previous waveforms deal with the inverter s operations 73 IV Measurements Fill the following cells LOAD c Uc Uc Sco
11. configuration can be studied with the CO 120 bench Fundamentals of power conversion are organized in chosen laboratory works This pedagogical bench can be used either in secondary degrees school of engineering or Polytechnic departments gt Half bridge voltage source inverter Commonly called inverter leg this configuration needs a central point power supply This is the basic scheme for the understanding of full bridge three phase and higher order inverters gt Full bridge voltage source inverter In this scheme a single DC power supply is used If the half bridge presents pedagogical interests the full bridge introduces industrial and commercial applications a Voltage source inverters are classified according to their output frequency range Line 50 Hz in France emergency power supplies for hospitals banks computer centre Up to 100 Hz AC variable speeds From 100 Hz to 40 kHz induction heating a The CO 120 is made of two parts Inverter scheme half or full bridge Command board dedicated to switching control output frequency command mode PWM Controlled switches are driven by a microcontroller a Practically the bench is very easy to use two front panels are available half bridge scheme Panel A and full bridge scheme Panel B Once the bridge configuration is chosen user can easily plug DC power supply loads meters scope current probe thus the lecturer is able
12. t aE sin ot ssin 36D Esino Jt If the output frequency matches resonance frequency of the RLC load the latter behaves as a selecting filter Harmonics are thus vanished Note when the output frequency is such as fo k the k harmonic will be considered as a fundamental Fill the following cells k rank 1 3 5 7 f Hz k f Hz fo 210 Hz I mA I theoretical Where I 4E Rr k 7 90 B PWM command a Single angle bipolar PWM a Select bipolar mode with 20 a Adjust parameters as follows f 210 Hz a 20 and b 0 a Enter Fill the following cells k rank 1 3 5 7 f Hz k f Hz fo 210 Hz a Two angles bipolar PWM a Adjust parameters as follows f 210 Hz a 24 and b 34 a Enter Fill the following cell k rank 1 3 5 7 f Hz k f Hz fy 210 Hz 91 The CO 200 bench is a pedagogical support with which the lecturer is able to introduce practical applications like induction heating emergency power supply or motor drive The following applications are dedicated to enhance the general knowledge of students a Induction heating a Emergency power supply a Induction motor speed control 92 INDUCTION HEATING I Introduction Induction heating can be used in a kitchen Nowadays electrical or gas cookers can b
13. two different waveforms are visualized Note Low frequency use CHOP sweeping mode Trigger Sweeping use Level button DC mode full signal both mean value and wave are displayed 2 Current probe LEM block The LEM module is a current probe based on Hall effect AC DC and AC DC signals can be measured Imax 3A Sensitivity 1V A scope 2 current probe COM AC DC If no current is measured a strap wire must be connected as follows Strap wire TECHNICAL SPECIFICATIONS ISECURITY ENVIRONMENT AND EMC A SECURITY This product complies with secured voltages Less than 50 Vrms AC Less than 120 V DC SWITCHING USER BRIDGE STRUCTURE COMMAND NO PANEL BENCH OFF NONE PANEL A HALF BRIDGE SQUARE WAVE BIPOLAR PWM PANEL B FULL BRIDGE SQUARE WAVE PWM DELAYED A Refer servicing to qualified service personnel only B ENVIRONMENT Use 10 C to 40 C Storage to prevent fire or electrical shock hazard do not expose this product to rain dust or moisture 19 C EMC This bench complies with EMC rules H ELECTRICAL CHARACTERISTICS A DC LINK Two kinds of DC power supply can be used Desk power supply Ref GPC 3030 90 VA CO 100 bench Note high capacitors must be added in order to make the power supply reversible Battery 12V 24 V ref CO 106 1 Half bridge VSI A central point power supply or a couple of batteries must be used A symmetrical pow
14. 1 a Result resistive load full bridge inverter R 100 Q E 12 V a 20 Closed devices PANEL A PANEL B mL RRL Fa Ts FG f ED To P 32 Third and fifth harmonics are vanished when a 23 6 and b mathematical values THD is 64 85 a Result resistive load R 100 Q E 12 V a 24 b 34 READINGS 5a OPTIOHS 33 33 3 V UNIPOLAR PWM In this technique the output voltage changes are from E to 0 and 0 to E E 0 E Therefore the magnitude of the harmonics are reduced by half The output waveform presents twice as much notches meaning that the frequency of the harmonics doubled a Switching angle a u E n 2 T 2n Closed devices PANEL B When a 30 third harmonic is vanished THD is 30 996 34 a Full bridge inverter with resistive load R 1009 E 12 V a 30 8139s READINGS WAVEFORM LLE OFF OPTIONS a Harmonics analysis Unipolar PWM a 30 1 2 11 m 13 14 15 16 17 18 13 third harmonic is vanished 35 a Switching angles a and b Third and fifth harmonics are vanished when a 17 6 and b 37 8 THD is 60 7 Parameters By default when 20 is pressed a 0 and b 0 b angle must be modified before a a and b must satisfy 0 lt a lt b lt x 2 36 a Result full bridge inverter resistive load R 100 Q E 12 V a 18 b 38 wa Beis a Harmonics analysis Unipolar PWM a 18 b
15. 4 command signal 19 Display LCD When square wave is selected output frequency is displayed When delayed mode is selected both output frequency an delay angle are displayed When bipolar or unipolar mode are selected both output frequency and PWM angles are displayed 20 Switching command Note by default square wave is engaged when power is turned on Press 20 to modify switching command 2 Red light on when square wave mode is selected 22 Red light on when delayed mode is selected 23 Red light on when bipolar PWM mode is selected 24 Red light on when unipolar PWM mode is selected 25 Parameters 26 Green light on when output frequency is being modified 27 Greenlight on when PWM first angle is being modified 28 Greenlight on when PWM second angle is being modified 29 Green light on when delay angle is being modified 30 Every time 30 is pressed the output frequency the first and second PWM angle are decreased respectively an amount of 1 Hz or 1 31 Every time 30 is pressed the output frequency the first and second PWM angle are increased respectively an amount of 1 Hz or 1 32 Enter Press 30 every time a parameter or a command mode is modified 17 WAVEFORM OBSERVATION VOLTAGE AND CURRENT CHARACTERISTICS 1 Waveform voltage measurement Caution short circuits may occur if user does not remember that many parts of the bench are grounded Differential probes or differential channels scope must be used when
16. Channel B output current ms Trig RT B 200mU a Harmonics analysis Square wave command 100 90 80 70 60 50 40 20 l Num 1 2 3 4 5 6 7 8 3 10 11 12 13 14 15 16 17 18 13 20 28 III DELAYED COMMAND The switching command of the second leg is delayed from the first leg by an angle called d u E PANEL B d must satisfy d lt x when d 60 third harmonic is vanished The pulse width is 120 wide 29 a Result resistive load R 100 Q E 12 V D 60 Sms iei g ar a Harmonics analysis Delayed command d 60 1 8 10 11 12 13 14 15 16 17 18 13 21 24 third harmonic 1s vanished 30 IV BIPOLAR PWM a PWM is a command technique that improves the quality of the output waveform In this technique harmonics are pushed to higher frequencies Thus the cut off frequency of the filter is increased Hence the filter components ie L and C size are reduced Moreover both frequency and amplitude can be independently controlled A PWM is basically obtained with a triangulation method or natural sampling Amplitude of the triangular wave carrier and sine wave modulating are compared to obtain PWM waveform Simple analog comparator can be used a Bipolar PWM Output voltage changes are from E or E u E x 2 T 2n Closed devices PANEL A PANEL B Switching angle a When a 20 third harmonic is vanished Total harmonic distorsion THD is 54 14 3
17. DC DC VALUE IV Spectrum analysis a f 210 Hz a C 2 2 uF L 0 25 H resonance is reached 1 Give quality factor Q Lwo Rr where Rr is the total resistance of the circuit 2 Give value of the load when resonance is reached What about the load impedance before and after resonance 3 Fourier series of output voltage is given as u t 2E sin at sina ssin 5oD n If output frequency matches resonance frequency of the RLC load the latter behaves as a selecting filter Harmonics are thus vanished Note when output frequency is such as fo k the k harmonic will be considered as a fundamental 59 Fill the following cells k rank 1 3 f Hz k f Hz fy 210 Hz I mA I theoretical Where I 4E R3 k x 60 B Bipolar PWM a Single angle mode a Select bipolar PM mode with 17 a Adjust parameters as follows f 210 Hz a 20 and b 0 a Enter Fill the following cells k rank 1 3 5 7 f Hz kf Hz fo 210 Hz a Two angles mode a Adjust parameters as follows f 210 Hz a 24 and b 34 a Enter Fill the following cells k rank 1 3 5 7 f Hz kf Hz fo 210 Hz 61 LABORATORY WORK FULL BRIDGE VOLTAGE SOURCE INVERTER PANEL B 62 RESISTIVE LOAD a The Panel B is set the be
18. Gy MONTAGE ONDULEUR DE TENSION MONOPHASE EN PONT MIA DC TO AC CONVERTERSINGLE PHASE INVERTER REF CO 1020 BENCH http WWW LANGLOIS FRANCE COM APPLIED PHYSICS PEDAGOGICAL MANUAL DC TO AC CONVERTER SINGLE PHASE INVERTER CO 1020 BENCH EAL Author H OBEIDI Translation F FALCO Lecturers in Applied Physics TABLE OF CONTENT PREAMBLE INTRODUCTION THE CO 120 BENCH PANEL A Half bridge voltage source inverter PANEL B Full bridge voltage source inverter PANEL A PANEL B WAVEFORM OBSERVATION VOLTAGE AND CURRENT CHARACTERISTICS TECHNICAL SPECIFICATIONS I Security environment and EMC II Electrical characteristics HI Safety and directions for use IV Components replacement VOLTAGE SOURCE INVERTER WAVEFORMS AND SWITCHING COMMAND I Switching II Square wave command HI Delayed command IV Bipolar PWM V Unipolar PWM 10 11 12 15 18 19 19 21 24 25 26 26 27 29 31 34 LABORATORY WORK HALF BRIDGE VOLTAGE SOURCE INVERTER Resistive load Inductive load Resonant load LABORATORY WORK FULL BRIDGE VOLTAGE SOURCE INVERTER Resistive load Inductive load Resonant load Induction heating Emergency power supply Induction motor drive system 39 42 51 56 62 63 80 87 93 98 101 PREAMBLE The improvement of silicon controlled rectifiers SCRs led to the development of a new area of applications called power elect
19. WM is being modified Every time 24 is pressed output frequency is decreased an amount of 1 Hz Every time 24 is pressed output frequency is increased an amount of 1 Hz Note press long time 24 or 25 if the required value is high 26 Enter Press 26 every time a parameter or a command mode is modified Note the 0 V level voltage of the bench power supply the low voltage of the bridge and 3 14 and 15 are grounded 14 PANEL B FULL BRIDGE VOLTAGE SOURCE INVERTER current probe AC DC Square wave Delayed Bipolar PWM Unipolar PWM SOURCE Frequency Delay angle d 15 l Inverter scheme 2 Power 3 Scope output used to visualized current 1 V A 4 Current probe Imax 3A 5 DC link 6 AC load 7 Current into transistor T1 Note a strap wire must be connected if no current characteristics in the leg is required 8 Current into diode D1 9 Current into diode D2 10 Current into transistor T2 Note a strap wire must be connected if no current characteristics in the leg is required 11 Current into diode D3 12 J Current into transistor T3 Note a strap wire must be connected if no current characteristics in the leg is required 13 Current into transistor T4 Note a strap wire must be connected if no current characteristics in the leg is required 14 Current into diode D4 15 TI command signal 16 T2 command signal 16 17 T3 command signal 18 T
20. cerned connector set the transistor and screw all connector terminals 2 Diode The diode must be correctly fixed Unscrew the concerned connector Place the diode cathode up and anode down and screw connector terminals 25 VOLTAGESOURCE INVERTER WAVEFORMS AND SWITCHING COMMAND IPOWER SWITCHES Mosfet and diode work into two states only Fully on conducting Fully of blocking Mosfet transistor is a controllable switch that can be turned on and off by low power control signals oe free wheeling diode bidirectionnal power switch D1 is a free wheeling diode that makes the power switch bidirectionnal whatever the load When u and I have opposite signs net power is negative the load provides energy to DC link When u and I have same signs net power is positive DC link provides energy to load 26 D is not pictured on the panel however it makes the current into the switch unidirectionnal Note switching losses due to rectifier may be considered II SQUARE WAVE COMMAND It is the easiest configuration a Half bridge inverter Panel A The top and the bottom switch has to be complementary ie if the top switch is closed on the bottom one must be off and vice versa a Full bridge inverter Panel B The switching in the second leg is 180 delayed from the first leg E 0 E 2T a Result Inductive load R 10Q L 44 mH core iron E 12 V battery Channel A output voltage
21. current 1 V A Current probe Imax 3A DC link centre point E DC link E AC load Imax 3A Current into D1 diode Current probe for visualization or meter for measuring intensity Current into T1 transistor Note a strap wire must be connected if no current characteristics in the leg is required 10 11 12 13 14 15 16 17 Current into D2 diode Current into T2 transistor Unused with Panel A Unused with Panel A T1 command signal T2 command signal Display LCD When square wave mode is selected output frequency is displayed When bipolar PWM mode is selected output frequency and switching angles are displayed Switching command Note by default square wave is engaged when power is turned on Press 17 to modify switching command 13 18 19 20 Red light on when square wave mode is selected Red light on when bipolar PWM is selected Once the switching command is fixed output frequency and switching angles can be modified a When square wave mode is able the output frequency can be modified only b When bipolar PWM mode is able both output frequency and switching angles can be modified Note by default square wave command and 100 Hz output frequency are set when power is turned on 21 22 23 24 25 Green light on when output frequency is being modified Green light on when first switching angle of PWM is being modified Green light on when second switching angle of P
22. e replaced by induction cooker A voltage source inverter supplies the primary windings of a transformer which generates a variable magnetic field Field lines are caught by metallic receptacle pan sauce pan An emf appears and as the receptacle is shorted circuit eddy currents circulate into This makes the metallic receptacle to get warmer because of Joules effect The pan acts as the secondary windings of the transformer cooker electromagnetic field induction coil primary inverter 93 II Scheme DC link DC power supply 30 V 3A Load Iron core transformer Primary winding n 125 turns 3A max Secondary winding n single loop turn metallic receptacle U NNN S N E NA induction cooker 94 B Panel is placed the bench is supplied rear side Select square wave command pressing 20 Adjust f to 50 Hz Enter Set DC link up to 30 V Put water into metallic loop Switch the bench on CAUTION metallic loop may be very hot 95 III Experiment 1 Is the transformer free on load or shorted ciruit 2 Evaluate eddy currents with a current crowbar MS 200 MS 220 3 Why does secondary current decrease while loop gets warmer 4 What kind of energy losses do appear Joule Hysteresis eddy currents a Hill the following cells E V Ui V L A Pi W Cosgi b A m Ux V Po W n 10 20 30 40 50
23. ed in order to select the fundamental of the output signal 2 Compare square wave and bipolar PWM commands 50 INDUCTIVE LOAD a Panel A is set the bench is supplied rear side Scheme DC link DC power supply current reversible Imax 3 A Load rheostat 10 Q 5 7 A or 33 Q 3 1 A in series with an iron core coil L 10 Q 0 1 H 1 4 H a Setup every components 51 a R L Load is connected D All strap wires are plugged a DC power supplies are connected El E2 E 24 V a The bench is turned on A Square wave command I Waveforms a L 0 2 H and f 50 Hz DClink Visualize and plot 1 t and igs t Inverter 1 Visualize simultaneously Vps and Vps2 2 Visualize simultaneously Vp and Vp 3 Visualize and plot simultaneously ir and irz currents into T1 and T2 4 Visualize and plot ipi and ip Load 1 Visualize an plot output voltage 2 Visualize and plot output current 52 II Analysis Both transistors are complementary as follows closed devices ETT NN O T 2 1 Is the output voltage modified by the coil 2 What about voltage losses due to power switches 3 Compare this output voltage with the one obtained with the square wave command 4 Explain the behaviour of the circuit give closed devices for each switching step give net power sign for each switching step HI
24. er supply is obtained with two capacitors which have the same value Then the DC link is equally split into two 2 Full bridge VSI A desk power supply or a single battery can be used 12 V or 24 V source voltage 20 B Electronic circuit The electronic board must be supplied by a symmetrical power supply 15 V Connections are situated at the rear side of the bench 15V 0v 15 V I C Power electronic devices 1 Rectifier diode In case of default or damage diode can be replaced by the following devices PLASTIC PACKAGE PLASTIC PACKAGE Rectifier TO 194 TO 220 AC Iray ou L 5A 8A 100 MR 821 MUR 810 VRRM 200 MUR 822 MUR 820 400 MR 824 MUR 840 n 21 2 Power transistor PLASTIC PACKAGE Power transistor TO 220 AB IrRMS 8A 9 13 A Rps on en 9 Rps on en 9 MTP 10N10 0 330 VpRM 100 IRF 520 0 300 IRF 532 0 250 BUZ 20 0 200 BUZ 72 0 200 150 IRF 633 0 500 IRF 631 0 400 VpRM MTP 12N20 0 350 200 IRF 632 0 500 BUZ 31 0 200 BUZ 32 0 400 Iray Maximum average forward current Vero repetitive peak inverse voltage Irgus RMS on state current Vpnw repetitive peak off state voltage D Load Caution Load must be fed with maximum current of 3A whatever bridge configuration resistive load Rheostats Ref ECO TUBE 320W 102 5 7 A 15 Q 4 5 A 22 Q 3 8 A 33Q 3 1 A 100 Q 1 8 A 220 Q 1
25. er to reach bipolar PWM II Waveforms Single angle PWM E 12V f 150 Hz a 40 and b 0 Two angles PWPM E 12V f 150 Hz a 25 and b 50 gt DClink Visualize and plot the source output current ig t gt Inverter 1 Visualize simultaneously Vps and Vps4 INV 2 Visualize simultaneously Vps and Vps3 INV 3 Visualize iri 172 15 and 154 currents into T1 T2 T3 and T4 76 gt Load 1 Visualize the output voltage 2 Visualize the output current III Analysis Transistors are complementary as follows closed devices From previous waveforms deal with the inverter s operations IV Measurements Fill the following cells LOAD c Uc Uc Ic Scope AC DC DC Ic VALUES V Spectrum analysis E 12 V Single angle E 12V f 150 Hz Fourier series of the output voltage is given as 77 00 u t Y gt bora sin 2k lot k 0 where boi wap ep Ek ens 1 What about the mean value 2 Output voltage spectrum a Adjust a up to 40 Visualize the output voltage spectrum b Adjust a up to 30 Visualize the output voltage spectrum Verify that the third harmonic 1s vanished c Derive the first five harmonics of the output voltage gt Two angles E 12V and f 250 Hz Fourier series of the output voltage is given as 00 u t Ybo sinQk Dot k 0 where b gt 41 wpe cos 2k Da cos 2k Db
26. ge laboratory work 3 Charger Inverter When a default occurs inverter can be substituted to line The battery DC link must be entirely loaded Thus in practical application battery output voltage is always regulated Block diagram CO1000 CO1020 line 50Hz battery Notes Electronics is not pictured on the previous block diagram If the 24 V bulb is replaced by a 230 V one a step up transformer must be used as follows This application may be used to illustrate a lecture or during a laboratory work 99 100 INDUCTION MOTOR DRIVE SYSTEM I Introduction Induction motors presents several advantages Robust no brushes High power weight ratio compared to DC motor Easy to manufacture However it is essentially a fixed speed machine Its speed is determined by the supply frequency Thus to vary its speed a variable frequency supply is needed Induction motor is present in many applications like conveyer line drives traction electric vehicles elevators any industrial process that requires variable speed operation For variable speed operation the supply is an inverter The frequency of the fundamental AC output voltage will set the speed of induction motor The inverter output frequency must be kept close to the required motor speed This is necessary as the induction motor operates under low slip conditions However in order to maintain constant torque the slip frequency must be maintai
27. isualize and plot the output current a Repeat previous actions with the following parameters E 12V f 200 Hz a 30 and b 45 HI Analysis Both transistors are complementary as follows Command switching gt PWM Single angle closed devices 0 a T a m T A 271 a 27 gt PWM two angles closed devices 0 x 27 48 IV Measurements Fill the following cells LOAD c Uc U lt Ic Ic Scope AC DC DC VALUES V Spectrum analysis E 12 V and f 200 Hz single angle Fourier series of the output voltage is given as 00 u t Y gt bona sin 2k 1 ot k 0 where b k 2cos 2k Da 1 eee 2k 1 1 Check the mean value is zero whatever a 2 Compare analysis spectrum when a 35 and a 20 b 0 and b 0 what about third harmonic Give the first five harmonics of Fourier series of the output voltage for both couple angles and compare with the spectrum analysis 49 two angles Fourier series of the output voltage is given as 00 u t Ybo sinQk Dot k 0 where b CB JH 2cos 2k Da 2cos 2k Db z 2k 1 1 Compare analysis spectrum when a 30 and a 24 b 45 and b 34 what about third and fifth harmonics Give the first five harmonics of Fourier series of the output voltage for both couple angles and compare with the spectrum analysis what kind of electronics filter ca be us
28. nch is supplied rear side Scheme DC link DC power supply Imax 3 A Load rheostat R 10 2 5 7 A or 33 Q 3 1 A 63 A Square wave command I Power switches a When the bench is turned on square wave mode and 100 Hz output frequency are displayed 1 Visualize and plot T1 and T4 command signals respectively c and Cm4 2 Measure and compare the command signal frequency to the displayed value 3 Note that whatever the chosen frequency both signals remain complementary with each other 4 Visualize and plot T2 and T3 command signals respectively Cm2 and cq Both signals must remain complementary II Waveforms Four strap wires are required Cy C Cr3 and Cz respectively associated to T1 T2 T3 and T4 a The load is plugged all strap wires are set a The bench is supplied 15 V DC link is plugged a Power is turned on adjust DC link up to 12 V gt DClink Visualize and plot the source output current ig t a Inverter 64 a A is grounded 1 Visualize simultaneously Vps and Vps4 INV a B is grounded 2 Visualize simultaneously Vps and Vps3 INV 3 Visualize iri 172 173 and 174 currents into T1 T2 T3 and T4 Load a Bis grounded 1 Visualize the output voltage 2 Visualize the output current III Analysis Transistors are complementary as follows closed devices PaeB i O T 2 f r2 RR 1 From p
29. ned over the range of supply frequencies When maximal motor flux is reached maximum torque is obtained and voltage to frequency ratio is kept constant Constant Voltz Herzt operation is used The motor is operated at rated slip at all supply frequencies Hence a constant torque area is obtained as a function of speed II Scheme Source reversible DC power supply 0 30 V 3 A Load 230 V singlephase induction motor associated to a speed sensor ref MO90 220 Step up transformer 12V 230V ref CO 107 101 X speed Note the step up transformer becomes useless according to the induction motor voltage supply a Set the Panel B and switch the bench on rear side a Set every components and select square wave command with 20 a Adjust the frequency up to 50 Hz a Enter a Set the DC source up to 12 V III Experiment 1 Let s consider the secondary winding of the transformer 102 a Visualize the secondary voltage uy use a step down probe b Measure both frequency and RMS value of uy 2 Speed control a Fill the following cells f Hz 0 30 50 80 100 150 n rpm speed b At which frequency does the motor stop Increase thus the DC source level c Deal with your results Plot P f E and m f E 3 Replace the AC motor by a series one and repeat the previous actions 103 SO0Z 80 8D 0ZOTOD
30. pe AC DC DC Ic l Q VALUES V Spectrum analysis E 12 V Single angle E 12V f 150 Hz Fourier series of the output voltage is given as 00 u t Yboy sin k Dot k 0 4E where b HER Ok 1 What about the mean value 2 Output voltage spectrum a Adjust a up to 35 Visualize the output voltage spectrum b Adjust a up to 20 Visualize the output voltage spectrum Verify that the third harmonic is vanished 74 2cos 2k Da 1 c Derive the first five harmonics of the output voltage gt Two angles E 12V and f 250 Hz Fourier series of the output voltage is given as 00 u t Y box 41 sin 2k Dot k 0 where bo E d 2cos 2k Da 2cos 2k Db n 2k 1 a Same questions with the following parameters a 30 a 24 b 45 b 34 b Derive first five harmonics c What kind of electronic filter can be used in order to keep the fundamental part of u t Compare square wave command with bipolar PWM command 75 D Unipolar PWM I Power switches a Select Bipolar PWM with 20 a Adjust parameters as follows f 150 Hz a 40 and b 0 a Enter 1 Measure the output frequency and visualize Cm1 Cm2 Cm3 Cm4 and a a Adjust new parameters as follows f 200 Hz a 30 and b 50 2 Measure the output frequency and visualize Cm1 Cm2 Cm3 a and b 3 Which values must verify a and b in ord
31. re required Cy cro Cy and C7 respectively associated to T1 T2 T3 and T4 a The load is plugged all strap wires are set a The bench is supplied 15 V DC link is plugged a Power is turned on adjust DC link up to 12 V gt DClink Visualize and plot the source output current ig t 68 a Inverter a A is grounded 1 Visualize simultaneously Vps and Vps4 INV a B is grounded 2 Visualize simultaneously Vps and Vps3 INV 3 Visualize ri 172 173 and 174 currents into T1 T2 T3 and T4 Load D B is grounded 1 Visualize the output voltage 2 Visualize the output current III Analysis Transistors are complementary as follows closed devices From previous waveforms deal with the inverter s operations You may use electrical instantaneous relationships 69 IV Measurements Fill the following cells LOAD c Scope AC DC DC Ic l Q VALUES V Spectrum analysis E 12 V Fourier series of the output voltage is given as 00 u t Y gt bora sin 2k Dot k 0 where bora 1 What about the mean value 2E cea cos 2k Id 2 Output voltage spectrum E 12 V and f 250 Hz a Adjust d up to 40 1 Visualize the output voltage spectrum a Adjust d up to 60 70 2 Visualize the output voltage spectrum Note that the third harmonic is vanished 3 Derive first five harmonics when d is
32. revious waveforms deal with the inverter s operations You may use electrical instantaneous relationships 2 Could you expect such output waveform 65 IV Measurements 1 Fill the following cells LOAD Oc Uc U lt ic Ic p Scope AC DC DC VALUES 2 Hill the following cells MOSFET r r Ir Ir VALUES V Spectrum analysis E 12 V f 100 Hz Fourier series of the output voltage is given as 1 What about the mean value 2 Visualize the output voltage spectrum 2 deal with the number of harmonics compare it with Fourier analysis 66 u t SB sin ot sinB Esino Jt 3 The fundamental is called ujf t define ul t as a function of E Give RMS expression Uj of ug as a function of E Calculate Uir What kind of electronic filter can be used in order to keep fundamental part of the output signal What are the main disadvantages with square wave command 67 B Delayed command I Power switches a Select delayed PWM with 20 a Adjust parameters as follows f 250 Hz d 40 a Enter 1 Visualize every command signals Cm1 Cm2 Cm3 and Cm4 Signals belonging to the same leg must be complementary and delayed angle d 2 Plot Cm1 Cm2 Cm3 and Cm4 3 Adjust d from 0 to highest value Which values must be verified by d in order to reach delayed command II Waveforms Four strap wires a
33. ronics Power electronics deals with controlled and conversion of electrical power of semiconductors devices wherein these devices operate as switches Since the SCRs are available the application area spread to many fields such as motor drives power supplies aviation electronics electronics converters The main task of power electronics is to control and convert electrical power from one form to another The CO 120 bench is a pedagogical device which illustrates the concept of AC waveform generation It is a DC to AC converter and deals with half bridge and full bridge configurations INTRODUCTION The DC to AC inverter converts DC signal from a DC link source to AC waveform to a load The output frequency can be fixed or modified The load is fed by a bridge composed of controlled switches Two configurations are available half bridge scheme one leg two switches and a full bridge scheme two legs four switches Note The CO 120 bench is an uncontrolled inverter its output frequency is independent from the mains frequency General block diagram DC to AC conversion Inverters can be classified as voltage source inverters VSIs and current source inverters CSIs A voltage source inverter is fed by a DC voltage whereas a current source inverter is fed by a stiff current source The CO 120 bench feeds resistive load inductive load resonant load and AC motors THE CO 120 BENCH Every single phase inverter
34. tively associated to T1 and T2 Two strap wires are required Cp and Cp respectively associated to D1 and D2 a The load is plugged Cr and Cr are set a The bench is supplied 15 V Symmetric DC link is plugged a Power is turned on adjust the DC link up to 12 V DClink a M is grounded a El and E2 must have the same waveforms both signals are superposed 43 a Visualize ig1 and ig2 with a current probe gt Inverter a Sis grounded now 1 Visualize simultaneously Vpsi and Vps2 INV 2 Visualize simultaneously i7 and irz currents into T1 and T2 3 Cp is plugged Visualize Ip current probe 4 Cp is removed Cp is plugged visualize Ip gt Load a Mis grounded 1 Visualize the output voltage 2 Visualize the output current III Analysis Both transistors are complementary as follows closed evices O T 2 1 What about voltage losses due to power switches 2 Deal with the inverter when 44 E u t Vpsi t et where E E E Vps2 t E u t 3 Show that the the inverter leg is a DC to AC waveform converter 4 Could you expect the output current waveform IV Measurements 1 Fill the following cells LOAD Uc Uc Uc Ic Ic scope AC DC DC l Q VALUES 2 Fill the following cells MOSFET transistor Urinv Ir Ir I Values V Spectrum analysis E 12 V f
35. to verify efficiently every benches Note Printed circuit and electronics board are protected by resettable switches called polyswitches The Pulse Width Modulation command is very flexible it can be modified from the command board This desk monitors pulse width output frequency and switching angles are displayed LCD The output waveform can be improved with the harmonic control using spectrum analyser or a scope including a spectrum analyser Note in order to underline the uncontrolled characteristic of the inverter mains can be replaced by batteries for electronics circuits and the DC link can be replaced by a battery of accumulator instead of a DC power supply Thus the inverter is line free PANEL A HALF BRIDGE VOLTAGE SOURCE INVERTER VSD SOURCE SOURCE HALF BRIDGE VSI on off i scope A current probe COM AC DC PANEL B FULL BRIDGE VOLTAGE SOURCE INVERTER VSD FULL BRIDGE VOLTAGE SOURCE INVERTER on off SOURCE scope M IA current probe AC DC Square wave Delayed Bipolar PWM Unipolar PWM Frequency PWM a angle PWM b angle Delay angle d HHH enter 11 PANEL A HALF BRIDGE VOLTAGE SOURCE INVERTER on off A3 SOURCE current probe AC DC 20 24 25 26 9 Inverter scheme Power Scope output used to visualized
36. vices l NEN s From previous waveforms deal with the inverter s operations 84 C Bipolar and Unipolar PWM commands I Bipolar PWM a Select bipolar mode with 20 a Adjust the following parameters Single angle E 24 V f 50 Hz a 20 and b 0 Two angles E 24 V f 50 Hz a 24 and b 34 a Enter 1 XVisualize both command signals and output voltage Note give closed devices for each switching step give net power sign for each switching step 2 Visualize the output voltage spectrum analysis II Unipolar PWM a Select bipolar mode with 20 a Adjust the following parameters Single angle E 24 V f 50 Hz a 40 and b 0 Two angles E 24 V f 50 Hz a 18 and b 38 a Enter 1 N Visualize both command signals and output voltage 85 Note give closed devices for each switching step give net power sign for each switching step 2 Visualize the output voltage spectrum analysis 86 RESONANT LOAD Scheme The load is composed of an iron core coil L 10 2 0 1 H 1 4 H in series with a capacitor C 22 uF 87 A Square wave command I Waveforms DClink Visualize and plot the source output current ig t 1 2 Inverter Visualize and plot Vos1 gt Vpso Vps3 and Vos4 Visualize and plot Vp Vp2 Vp and Vp4 The following table may be useful

USER`S MANUAL

Contents

Download Pdf Manuals

Related Search

Related Contents