POWER ELECTRONICS EPE 550 CIRCUITS, DEVICES, AND APPLICATIONS ELECTRICAL DRIVES:

1. POWER ELECTRONICS EPE 550 CIRCUITS, DEVICES, AND APPLICATIONS ELECTRICAL DRIVES: An Application of Power Electronics Eng.MohammedAlsumady

2. CONTENTS Power Electronic Systems Modern Electrical Drive Systems Power Electronic Converters in Electrical Drives :: DC and AC Drives Modeling and Control of Electrical Drives :: Current controlled Converters :: Modeling of Power Converters :: Scalar control of IM

3. Power Electronic Systems What is Power Electronics ? A field of Electrical Engineering that deals with the application of power semiconductor devices for the control and conversion of electric power sensors Power Electronics Converters Load • Input • Source • AC • DC • unregulated Output - AC - DC POWER ELECTRONIC CONVERTERS – the heart of power in a power electronics system Controller Reference

4. Power Electronic Systems Why Power Electronics ? Power semiconductor devices Power switches isw = 0 ON or OFF + vsw − isw Ploss = vsw× isw = 0 + vsw − = 0 Losses ideally ZERO !

5. Power Electronic Systems Why Power Electronics ? Power semiconductor devices Power switches K K - Vak + - Vak + K G - Vak + G ia ia A A ia A

6. Power Electronic Systems Why Power Electronics ? Power semiconductor devices Power switches D C iD ic + VDS - + VCE - G G S E

7. Power Electronic Systems Why Power Electronics ? High frequency transformer Passive elements + VL- + VC- iL iC + V1 - + V2 - Inductor

8. Power Electronic Systems Why Power Electronics ? sensors Power Electronics Converters • Input • Source • AC • DC • unregulated IDEALLY LOSSLESS ! Output - AC - DC Load Controller Reference

9. Power Electronic Systems Why Power Electronics ? Other factors: • Improvements in power semiconductors fabrication • Power Integrated Module (PIM), Intelligent Power Modules (IPM) • Decline cost in power semiconductor • Advancement in semiconductor fabrication • ASICs • FPGA • DSPs • Faster and cheaper to implement complex algorithm

10. Advancement in semiconductor fabrication • A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable". The FPGA configuration is generally specified using a hardware description language (HDL), similar to that used for an application-specific integrated circuit (ASIC) circuit diagrams were previously used to specify the configuration, as they were for ASICs, but this is increasingly rare). FPGAs can be used to implement any logical function that an ASIC could perform. The ability to update the functionality after shipping, partial re-configuration of the portion of the design and the low non-recurring engineering costs relative to an ASIC design (notwithstanding the generally higher unit cost), offer advantages for many applications. • FPGAs contain programmable logic components called "logic blocks", and a hierarchy of reconfigurable interconnects that allow the blocks to be "wired together"—somewhat like many (changeable) logic gates that can be inter-wired in (many) different configurations. Logic blocks can be configured to perform complex combinational functions, or merely simple logic gates like AND and XOR. In most FPGAs, the logic blocks also include memory elements, which may be simple flip-flops or more complete blocks of memory. • In addition to digital functions, some FPGAs have analog features. The most common analog feature is programmable slew rate and drive strength on each output pin, allowing the engineer to set slow rates on lightly loaded pins that would otherwise ring unacceptably, and to set stronger, faster rates on heavily loaded pins on high-speed channels that would otherwise run too slow. Another relatively common analog feature is differential comparators on input pins designed to be connected to differential signaling channels.

11. A field-programmable gate array (FPGA) • The FPGA industry sprouted from programmable read-only memory (PROM) and programmable logic devices (PLDs). PROMs and PLDs both had the option of being programmed in batches in a factory or in the field (field programmable), however programmable logic was hard-wired between logic gates. • A recent trend has been to take the coarse-grained architectural approach a step further by combining the logic blocks and interconnects of traditional FPGAs with embedded microprocessors and related peripherals to form a complete "system on a programmable chip“.

12. A field-programmable gate array (FPGA)

13. Power Electronic Systems Some Applications of Power Electronics : Typically used in systems requiring efficient control and conversion of electric energy: Domestic and Commercial Applications Industrial Applications Telecommunications Transportation Generation, Transmission and Distribution of electrical energy Power rating of < 1 W (portable equipment) Tens or hundreds Watts (Power supplies for computers /office equipment) kW to MW : drives Hundreds of MW in DC transmission system (HVDC)

14. Modern Electrical Drive Systems • About 50% of electrical energy used for drives • Can be either used for fixed speed or variable speed • 75% - constant speed, 25% variable speed (expanding) • Variable speed drives typically used PEC to supply the motors • IM: Induction Motor • PMSM: Permanent Magnet Synchronous Motor • SRM: Switched Reluctance Motor • BLDC: Brushless DC Motor DC motors (brushed) • AC motors • - IM • PMSM SRM BLDC

15. Permanent Magnet Synchronous Motor • The Permanent Magnet Synchronous motor is a rotating electric machine where the stator is a classic three phase stator like that of an induction motor and the rotor has permanent magnets. In this respect, the PM Synchronous motor is equivalent to an induction motor, except the rotor magnetic field in case of PMSM is produced by permanent magnets. The use of a permanent magnet to generate a substantial air gap magnetic flux makes it possible to design highly efficient PM motors. Medium construction complexity, multiple fields, delicate magnets • High reliability (no brush wear), even at very high achievable speeds • High efficiency • Low EMI • Driven by multi-phase Inverter controllers • Sensorless speed control possible • Higher total system cost than for DC motors • Smooth rotation - without torque ripple • Appropriate for position control

16. Permanent Magnet Synchronous Motor

17. Switched Reluctance (SR) Motor • Switched reluctance (SR) motor is a brushless AC motor. It has simple mechanical construction and does not require permanent magnet for its operation. The stator and rotor in a SR motor have salient poles. The number of poles presence on the stator depends on the number of phases the motor is designed to operate in. Normally, two stator poles at opposite ends are configured to form one phase. In this configuration, a 3-phase SR motor has 6 stator poles. The number of rotor poles are chosen to be different to the number of stator poles. A 3-phase SR motor with 6 stator poles and 4 rotor poles is also known as a 6/4 3-Phase SR motor. • SR motor has the phase winding on its stator only. Concentrated windings are used. The windings are inserted onto the stator poles and connected in series to form one phase of the motor. In a 3-Phase SR motor, there are 3 pairs of concentrated windings and each pair of the winding is connected in series to form each phase respectively.

18. Future Electric Motors Build will be SR Motors • The small-size SR motor was developed by Akira Chiba, professor at the Department of Electrical Engineering, Faculty of Science & Technology, Tokyo University of Science. • The prototyped SR motor has the same size as the 50kW synchronous motor equipped in the second-generation Toyota Prius. Currently all produced Electric cars are equipped with a synchronous motor whose rotor is embedded with a permanent magnet. • But as the permanent magnets are getting more and more pricey (the price has doubled or tripled) because of higher demand, the future of SR Motors is now imminent. • A four-phase 8/6 switched-reluctance motor is shown in cross section. In order to produce continuous shaft rotation, each of the four stator phases is energized and then de-energized in succession at specific positions of the rotor as illustrated.

19. Future electric motors build will be SR Motors.

20. Brushless DC Motor • A BLDC motor has permanent magnets which rotate, and a fixed armature, eliminating the problems of connecting current to the moving armature. An electronic controller replaces the brush commutator assembly of the brushed DC motor, which continually switches the phase to the windings to keep the motor turning. The controller performs similar timed power distribution by using a solid-state circuit rather than the brush commutator system. • BLDC motors offer several advantages over brushed DC motors, including more torque per weight, more torque per watt (increased efficiency), increased reliability, reduced noise, longer lifetime (no brush and commutator erosion), elimination of ionizing sparks from the commutator, and overall reduction of electromagnetic interference (EMI). With no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter.

21. BLDC: Brushless DC Motor

22. Modern Electrical Drive Systems Classic Electrical Drive for Variable Speed Application : • Bulky • Inefficient • inflexible

23. Modern Electrical Drive Systems Typical Modern Electric Drive Systems Electric Motor Power Electronic Converters Electric Energy Electric Energy - Regulated - Mechanical Energy Electric Energy - Unregulated - POWER IN Motor Load PowerElectronic Converters feedback Controller Reference

24. Modern Electrical Drive Systems Example on Variable Speed Drives (VSD) application Variable Speed Drives Constant speed valve Supply motor pump Power out Power In Power loss Mainly in valve

25. Modern Electrical Drive Systems Example on Variable Speed Drives (VSD) application Variable Speed Drives Constant speed valve Supply Supply motor pump motor PEC pump Power out Power out Power In Power In Power loss Power loss Mainly in valve

26. Modern Electrical Drive Systems Example on VSD application Variable Speed Drives Constant speed valve Supply Supply motor pump motor PEC pump Power out Power out Power In Power In Power loss Power loss Mainly in valve

27. Modern Electrical Drive Systems Example on VSD application Electric motor consumes more than half of electrical energy in the US Variable speed Fixed speed Improvements in energy utilization in electric motors give large impact to the overall energy consumption HOW ? Replacing fixed speed drives with variable speed drives Using the high efficiency motors Improves the existing power converter–based drive systems

28. Modern Electrical Drive Systems Overview of AC and DC drives DC drives: Electrical drives that use DC motors as the prime mover Regular maintenance, heavy, expensive, speed limit Easy control, decouple control of torque and flux AC drives: Electrical drives that use AC motors as the prime mover Less maintenance, light, less expensive, high speed Coupling between torque and flux – variable spatial angle between rotor and stator flux

29. Modern Electrical Drive Systems Overview of AC and DC drives Before semiconductor devices were introduced (<1950) • AC motors for fixed speed applications • DC motors for variable speed applications After semiconductor devices were introduced (1960s) • Variable frequency sources available – AC motors in variable speed applications • Coupling between flux and torque control • Application limited to medium performance applications – fans, blowers, compressors – scalar control • High performance applications dominated by DC motors – tractions, elevators, servos, etc

30. Modern Electrical Drive Systems Overview of AC and DC drives After vector control drives were introduced (1980s) • AC motors used in high performance applications – elevators, tractions, servos • AC motors favorable than DC motors – however control is complex hence expensive • Cost of microprocessor/semiconductors decreasing –predicted 30 years ago AC motors would take over DC motors

31. Modern Electrical Drive Systems Overview of AC and DC drives Extracted from Boldea & Nasar

32. Power Electronic Converters in Electrical Drive Systems Converters for Motor Drives (some possible configurations) DC Drives AC Drives DC Source AC Source DC Source AC Source DC-AC-DC DC-DC AC-AC AC-DC-AC AC-DC-DC DC-AC DC-DC-AC AC-DC Variable DC Const. DC FCC NCC

33. Power Electronic Converters in ED Systems Converters for Motor Drives Configurations of Power Electronic Converters depend on: Sources available Type of Motors Drive Performance - applications - Braking - Response - Ratings

34. Power Electronic Converters in ED Systems DC DRIVES Available AC source to control DC motor (brushed) AC-DC-DC AC-DC Uncontrolled Rectifier Single-phase Three-phase Control Control DC-DC Switched mode 1-quadrant, 2-quadrant 4-quadrant Controlled Rectifier Single-phase Three-phase

35. Power Electronic Converters in ED Systems DC DRIVES AC-DC + Vo  50Hz 1-phase Average voltage over 10ms 50Hz 3-phase + Vo  Average voltage over 3.33 ms

36. Power Electronic Converters in ED Systems DC DRIVES AC-DC + Vo  90o 180o 50Hz 1-phase Average voltage over 10ms 50Hz 3-phase + Vo  90o 180o Average voltage over 3.33 ms

37. ia Vt + Vt  3-phase supply Q1 Q2 Q3 Q4 Ia Power Electronic Converters in ED Systems DC DRIVES AC-DC - Operation in quadrant 1 and 4 only

38. + Vt  3-phase supply 3-phase supply  Q1 Q2 Q3 Q4 T Power Electronic Converters in ED Systems DC DRIVES AC-DC

39. R1 F1 3-phase supply + Va - F2 R2  Q1 Q2 Q3 Q4 T Power Electronic Converters in ED Systems DC DRIVES AC-DC

40. Power Electronic Converters in ED Systems DC DRIVES AC-DC Cascade control structure with armature reversal (4-quadrant): iD w Firing Circuit iD,ref Current Controller wref Speed controller + + _ _ iD,ref Armature reversal iD,

41. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC control Uncontrolled rectifier Switch Mode DC-DC 1-Quadrant 2-Quadrant 4-Quadrant

42. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC control

43. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Two-quadrant Converter Va T1 D1 + Vdc  ia Q2 Q1 Ia + Va - D2 T2 T1 conducts  va = Vdc

44. Va Eb Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Two-quadrant Converter Va T1 D1 + Vdc  ia Q2 Q1 Ia + Va - D2 T2 T1 conducts  va = Vdc D2 conducts  va = 0 Quadrant 1The average voltage is made larger than the back emf

45. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Two-quadrant Converter Va T1 D1 + Vdc  ia Q2 Q1 Ia + Va - D2 T2 D1 conducts  va = Vdc

46. D1 conducts  va = Vdc Eb Va Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Two-quadrant Converter Va T1 D1 + Vdc  ia Q2 Q1 Ia + Va - D2 T2 T2 conducts  va = 0 Quadrant 2The average voltage is made smallerr than the back emf, thus forcing the current to flow in the reverse direction

47. vc 2vtri Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Two-quadrant Converter + vA - Vdc 0 + vc

48. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Four-quadrant Converter leg A leg B D3 + Vdc  D1 Q1 Q3 + Va D4 D2 Q4 Q2 Positive current va = Vdc when Q1 and Q2 are ON

49. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Four-quadrant Converter leg A leg B D3 + Vdc  D1 Q1 Q3 + Va D4 D2 Q4 Q2 Positive current va = Vdc when Q1 and Q2 are ON va = -Vdc when D3 and D4 are ON va = 0 when current freewheels through Q and D

50. Power Electronic Converters in ED Systems DC DRIVES AC-DC-DC DC-DC: Four-quadrant Converter leg A leg B D3 + Vdc  D1 Q1 Q3 + Va D4 D2 Q4 Q2 Positive current Negative current va = Vdc when Q1 and Q2 are ON va = Vdc when D1 and D2 are ON va = -Vdc when D3 and D4 are ON va = 0 when current freewheels through Q and D