Encoderless Control of Synchronous Machines - State of the Art. Ralph M. Kennel, Technische Universität München, Germany

Transcription

1 Encoderless Control of Synchronous Machines - State of the Art Ralph M. Kennel, Technische Universität München, Germany Ralph.Kennel@tum.de

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3 Reasons for Industrial Applications of Drives with encoderless Control: Cost Reliability Robustness???? is encoderless (sensorless) resulting in additional cost??? Page 3

4 Industrial Drives with Sensorless Control since several years / decades sensorless control is investigated and published on conferences and magazines - acceptance in industry, however, is rather low Why? new ideas and concepts are interesting for industry, only if they do not result in higher cost or higher effort!!! What does that mean for industrial drives with sensorless control? no additional or more powerful processors / controllers no additional hardware or additional sensors (e. g. voltage sensors) no increased installation effort with respect to parameter adjustments Page 4

5 Industrial Drives with Sensorless Control since several years / decades sensorless control is investigated and published on conferences and magazines - acceptance in industry, however, is rather low Why? new ideas and concepts are interesting for industry, only if they do not result in higher cost or higher effort!!! What does that mean for industrial drives with sensorless control? no additional or more powerful processors / controllers no additional hardware or additional sensors (e. g. voltage this sensors) was valid no increased installation effort with respect to parameter from adjustments 2000 to 2010 Page 5

6 Industrial Drives with Sensorless Control since several years / decades sensorless control is investigated and published on conferences and magazines - acceptance in industry, however, is rather low Why? new ideas and concepts are interesting for industry, only if they do not result in higher cost or higher effort!!! What does that mean for industrial drives with sensorless control? single scheme for wide speed range (no phase over) no additional noise (except usual noise by inverter supply) insensitivity with respect to parameter variations Page 6

7 Industrial Drives with Sensorless Control since several years / decades sensorless control is investigated and published on conferences and magazines - acceptance in industry, however, is rather low Why? new ideas and concepts are interesting for industry, only if they do not result in higher cost or higher effort!!! What does that mean for industrial drives with sensorless control? single scheme for wide speed range (no phase over) no additional noise (except usual noise by inverter supply) insensitivity with respect to parameter variations What does industry think today? Page 7

8 Industrial Drives with Sensorless Control Actual Requirements from Industry there should be a single concept for encoderless control single scheme for wide speed range (no phase over) in case there is a signal to be injected for speed/position detection no additional noise for the complete speed range (from standstill to maximum speed) this should not cause any additional noise - except usual noise caused by inverter supply with standard PWM parameters of electrical machine and/or power elctronics should not impact the performance of encoderless control too much (a certain impact is acceptable) insensitivity with respect to parameter variations Page 8

9 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 9

10 8th IEEE International Symposium on Sensorless Control for Electrical Drives Alfio Consoli International Memorial Meeting SLED September 2017, Catania, Sicily, ITALY General Chairs Giuseppe Scarcella Mario Cacciato 1/22/

11 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 11

12 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 12

13 Field oriented control of PMSM rotor position needed Page 13

14 Fundamental model based position estimation when knowing voltage as well as current it is possible to estimate rotor speed and rotor position Page 14

15 Calculation of Speed by Fundamental Model is not Practicable for Very Low Speeds... because the voltage signal becomes very small errors between real voltage and values used for calculation cannot be avoided and become more significant DC components of these errors let the integrators for flux calculation drift away the calculated speed gets more and more incorrect is an encoder/resolver the only feasable solution?? Page 15

16 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 16

17 Categories of Machine Models for Sensorless Control Page 17

18 fundamental model high frequency injection simple realisation does not work at frequency 0 parameter dependencies Basic Principles of Encoderless Control Page 18

19 fundamental model high frequency injection simple realisation does not work at frequency 0 parameter dependencies current injection voltage injection measuring voltage is high enough additional voltage sensors transient current response no additional hardware very short measuring time stationary current response standard microcontroller sufficient very small measuring current Page 19

20 INFORM method according to M. Schroedl (Technical University of Vienna, Austria) this is basically a transient voltage injection method currents have to be sensed at specific times!!! when using standard current transducers these cannot be synchronized with PWM the hardware of a standard industrial drive has to be changed nevertheless this method comes close to industrial needs! Page 20

21 Stationary Signal Injection Methods according to R. Lorenz, S.-K. Sul, R. Kennel, etc. the basic idea is to use the electrical machine itself as a resolver!!! Page 21

22 Resolver injection of a stationary (sinusoidal) high frequency signal sensing of a two-dimensional stationary (sinusoidal) signal response Tamagawa R1 S2 u 1 ( 0 Stator u e Rotor u R Stator u 2 R2 S1 Stator u 1 S3 S4 u 2 ( 0 Page 22

23 Stationary Signal Injection Methods according to R. Lorenz, S.-K. Sul, R. Kennel, etc. the basic idea is to use the electrical machine itself as a resolver!!! a resolver is nothing else but an electrical machine can we operate the motor itself like a resolver? if the machine itself is a resolver (encoder) is that really an encoderless control??? now we do the same with an electrical AC machine Page 23

24 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 24

25 Standard industrial servo PMSM distributed stator windings surface mounted PM Page 25

26 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 26

27 Fundamental Frequency Excitation (in - coordinates) Page 27

28 High Frequency Excitation (in - coordinates) Page 28

29 Machine Model for High Frequency Signals u (F) c r s i (F) c l (F) sσ (F) c di dt j l a (F) sσ i (F) c l (F) sσ l 0 sσd l 0 sσq Page 29

30 Machine Model for High Frequency Signals u (F) c r s i (F) c l (F) sσ (F) c di dt j l a (F) sσ i (F) c l (F) sσ l 0 sσd l 0 sσq Page 30

31 High Frequency Behaviour of the Machine Model Page 31

32 injection of high frequency voltages fundamental voltage phasor/vector fundamental current phasor/vector injected high frequency voltage phasor/vector high frequency current phasor/vector (response) Page 32

33 injection of high frequency voltages fundamental voltage phasor/vector fundamental current phasor/vector injected high frequency voltage phasor/vector high frequency current phasor/vector (response) Page 33

34 injection of high frequency voltages fundamental voltage phasor/vector fundamental current phasor/vector injected high frequency voltage phasor/vector high frequency current phasor/vector (response) Page 34

35 injection of high frequency voltages fundamental voltage phasor/vector fundamental current phasor/vector injected high frequency voltage phasor/vector high frequency current phasor/vector (response) Page 35

36 Injection of High Frequency Rotating Phasors rotating voltage phasor u c elliptic current response i c Page 36

37 Position Information of Salient Rotors in High Frequency Rotating Phasors machine responds on a rotating voltage phasor with an elliptic current response ellipse is correlated with the geometric anisotropy rotor position information is included of the rotor in the high frequency current elliptic current response i c (rotating) Page 37

38 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 38

39 Injection of High Frequency Alternating (Pulsating) Voltage Phasors composing an alternating (pulsating) voltage phasor by two phasors rotating in opposite direction advantage : no rotational (HF) field no additional torque Page 39

40 High Frequency Current Response of a Synchronous Machine Page 40

41 Current Response of a Misoriented System voltage and current show different orientation!! Page 41

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47 Tracking Scheme for Magnetic Anisotropies i i (Fˆ) cd (Fˆ) cq Ksin t Ksin c l cq c tlcq lcd ˆ a Page 47

48 Tracking Scheme for Magnetic Anisotropies Tracking the estimated angle of the rotor flux by controlling i cq to 0 Page 48

49 Encoderless Control Structure step response of the PLL; PLL is locked after ca ms Page 49

50 control structure of an encoderless control with alternating high frequency signal injection the estimated angle can be used for field orientation as well as for speed or position control of synchronous machines Page 50

51 north and south pole can be distinguished a) theoretisch b) experimentell trajectory of stator admittance (SMPMSM, carrier frequency f c = 0.5 khz) Stator Admittance in Complex Plane Page 51

52 north and south pole can be distinguished a) theoretisch b) experimentell trajectory of stator admittance (SMPMSM, carrier frequency f c = 0.5 khz) Stator Admittance in Complex Plane Page 52

53 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 53

54 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 54

55 Injection of 2 Voltage Pulses in +d and -d Pulses in +d and d Evaluate current response 0 difference 180 difference Page 55

56 Sprungantwort der Drehzahlregelung Drive with Speed Control Page 56

57 Sprungantwort der Lageregelung Step Response of Encoderless Position Control Page 57

58 Stationary Signal Injection Methods according to R. Lorenz, S.-K. Sul, R. Kennel, etc. when the basic idea is to use the electrical machine itself as a resolver the performance of this type of encoderless control must be more or less equal to a control with a low performance resolver because the electrical machine is designed to be an electrical machine and not to be a good resolver! Page 58

59 Stationary Signal Injection Methods according to R. Lorenz, S.-K. Sul, R. Kennel, etc. when the basic idea is to use the electrical machine itself as a resolver the performance of this type of encoderless control must be more or less equal to a control with a low performance resolver because the electrical machine is designed to be an electrical machine and not to be a good resolver! Page 59

60 Results the tracking control scheme presented here synchronizes on the saturation anisotropy of a synchronous machine. the tracking control scheme is not depending on any machine parameter. the size of additional software for the tracking control is comparable to the software of a rotor model for the field oriented control of an induction machine. the high frequency current signal can be measured together with the fundamental current by the standard current transducers of a standard drive inverter. Page 60

61 Practical Experience with an Industrial Servo Drive Implementation of a sensorless control into a servo drive of training of a development engineer 2 x 1 week in our laboratory programming of additional software in manufacturer s factory delivery of prototype after ca. 3 months presentation on Hanover Fair in April 2006 Page 61

62 Industrial Needs The proposed estimation method is simple The sensorless control scheme presented here and therefore suitable for usual microcontrollers no additional or more powerful processors / controllers does not need additional voltage measurement devices - neither on the machine/motor side nor on the line side no additional hardware or additional sensors (e. g. voltage sensors) The phase tracking method is very robust to variations of the system parameters no increased installation effort with respect to parameter adjustments Page 62

63 meanwhile : more industrial applications WEG (Brazil) as mentioned before BAUMÜLLER same experiences as WEG TRÜTZSCHLER successful application ZIEHL-ABBEGG successful application in fans two more companies in textile machinery who do not want to be mentioned ABM Greiffenberger advertising actively on SPS/IPC/Drives 2010

64 meanwhile : some more experiences in encoderless control the tracking control can also track other points without orthogonal component a) theoretisch b) experimentell trajectory of stator admittance (SMPMSM, carrier frequency f c = 0.5 khz) what are the benefits?

65 meanwhile : some more experiences in encoderless control high frequency injection in d direction, because negligible influence on torque... no low pass filter in the feedback loop of current control... no impact on drive dynamics disadvantage : inverter non-linearities produce additional anisotropy interesting solution : high frequency injection in q direction

66 Injection Angle of 90 (in q direction) Benefits : Compensation of Inverter Nonlinearities Better Use of Voltage Hexagon

67 Sector Transition of the Alternating Carrier Excitation a) injection angle j inj = /2 b) injection angle j inj = /3 high frequency carrier current transition during sector changes with different injection angles j inj

68 what about asynchronous machines? (induction motors) any motor provides several (magnetic) anisiotropies in the case of synchronus machines these rotate synchronously it does not matter, which anisotropy is tracked in the case of asynchronus machines the different anisotropies do not rotate synchronously the tracking controller cannot identify specific anisotropies!!

69 Magnetic Anisotropies Present in Induction Machines 1. saturation anisotropies (main field saturation in the stator!) 2. rotor based saliencies (slots) 3. saliency due to rotor eccentricity 4. anisotropies caused by inverter non-linearities not all of these anisotropies are exploitable, relevant or even wanted.

70 the concept of encoderless control as presented here works similar to radio broadcasting : the information of rotor position is modulated by a high frequency signal the information is demodulated / extracted from motor currents Page 70

71 modulation on a high frequency carrier by the motor itself works fine!! further research to be done!!

72 Further Research Activities are there demodulation schemes being able to distinguish the different current responses resulting from rotor and field anisotropies? design of a parameter independant encoserless control for induction machines without voltage sensors

73 Further Research Activities are there demodulation schemes being able to distinguish the different current responses resulting from rotor and field anisotropies? design of a parameter independant encoserless control for induction machines without voltage sensors

74 Signal Injection Method according to J. Holtz, H.Pan, etc. this is basically a current injection method voltage sensors are necessary!!! it is possible to use current derivatives instead of motor voltages measuring current derivatives, however, by standard current transducers is not really possible Page 74

75 Basic Principle of Transient Current Response Detection just use the voltage pulses provided by the PWM anyway detect the anisotropy dependant (transient) current responses Practical Problems sometimes the original PWM pulses are too short PWM patterns have to be modified ( several schemes!) current derivation is needed to detect inductance variations

76 3 2 cos 1 ) ( 3 4 cos 1 ) ( ) cos( 2 ) ( n l l K dt u di n l l K dt u di n l l K dt u di c b a the stator leakage inductance variations can be detected in the motor voltages or in the current derivations Position Estimation by Pulse Injection

77 aus Juliet-Arbeit : Bild 5.1: Stromableitung the availability of the current derivations would be very helpful

78 Current Derivative Sensors as used at the University of Malta

79 Coax Sensor Responses as measured at the University of Malta di/dt magnitude (volts) ramp from A is applied in 20 μs x Time (seconds) x 10-4 Response of the 3 different coax sensors used. Blue trace shows results using at 5:20 turn sensor, Red shows a 5:5 turn sensor and black shows results for a 3:3 turn sensor, the settling time for three cases is approximately equivalent displaying a deviation from a mean of 10μs of +/-5%

80 Coaxial Coils as used at Wuppertal University

81 Derivative Output Signal of Coaxial Coil

82 further investigations will industry accept (additional) current derivation sensors (e. g. Rogowski type)? probably not (nearly the same problem as with additional voltage sensors) can the standard current sensors be used for derivation measurement? Measuring sequentially 2 currents and calculating the difference is possible problem 1 : measuring time cannot be synchronized with PWM problem 2 : small differences need high resolution A/D conversion can standard current sensors provide an additional derivation output??? (e. g. based on the compensation voltage available inside)

83 Compensation Current Sensor compensate the magnetic field of the primary current by a second magnetic field produced by a secondary coil the respective compensation controller/regulator is feeding the secondary coil by a voltage u = L di/dt a current derivative signal does already exist inside the current sensor however, is the signal quality sufficient for sensorless/encoderless control of induction machines??? can this be made available for customers???

84 Compensation Current Sensor contact meetings with current sensor manufacturers have already taken place current sensor manufacturers hesitate to provide the internal signal for external use, because the basic internal signal has bad accuracy they fear a hint for their business by any bad accuracy of any signal in the data sheet sensorless/encoderless control, however, does not require good accuracy of the current deviation signal, it requires good linearity only

85 Compensation Current Sensor contact meetings with current sensor manufacturers have already taken place current sensor manufacturers hesitate to provide the internal signal for external use, because the basic internal signal has bad accuracy they fear a hint for their business by any bad accuracy of any signal in the data sheet sensorless/encoderless control, however, does not require good accuracy of the current deviation signal, it requires good linearity only

86 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 86

87 meanwhile : in certain applications difficulties occur there are motor designs, with difficulties in encoderless control under specific operation conditions there are motor designs, which cannot be controlled encoderless(ly) by an anisotropy tracking (PLL) controller at all

88 which electrical machines can be controlled without an encoder? high frequency current response i c contains the rotor position information. the rotor position can be sensed by a parameter independant tracking control (PLL) requirement: there must be a difference between inductances in d- and in q-direction lcq l cd 0

89 which electrical machines can be controlled without an encoder? this requirement sounds easy to fulfill it is, however, more difficult than expected this can be shown by the example of a synchronous reluctance machine providing a significant magnetic anisotropy lcq l cd 0

90 Further Research Activities Synchronous Reluctance Machines Synchronous Reluctance Machines should be ideal for encoderless control with respect to their great anisotropy

91 Inductances of a Synchronous Reluctance Machine flux barriers magnetising curves of a synchronous reluctance machine cross section of a synchronous reluctance machine 3 phase, 2 pole pairs

92 Inductances of a Synchronous Reluctance Machine ψ s i s l s l s ψ i s s l s = secantic inductance secantic inductances of a synchronous reluctance machine

93 s s s s i l i ψ dt d s s s i l u dt d s s s s i i l u dt d d d s s s s s s s s i i i l i i l u s s s s s s c i i l i i l l d d detection of an anisotropy seems to be difficult High Frequency Inductance

94 some more experiences in encoderless control as a result, it should be nearly impossible to control a synchronous reluctance machine by a high frequency injection tracking control a respective project, however, was performed successfully why? because the saturation depending anisotropy in the stator is detected!!!

95 our experience : the high frequency injection scheme does not detect the geometric anisotropy of a synchronous reluctance machine it tracks the saturation in the stator!!! can anybody respond : do the high frequency magnetic flux lines use the same paths as the fundamental field???

96 Further Research Activities Synchronous Reluctance Machines Synchronous Reluctance Machines should be ideal for encoderless control with respect to their great anisotropy but : absolute and differential inductances are different characteristics under high saturation the tracking controller might not be able to track further investigation: high injection frequency lower penetration depth in the rotor injection inductance leakage inductance!!

97 some more experiences in encoderless control Bolognani reported (in 2006?) saturation in q direction increases under load difference between l cq and l cd decreases... and vanishes at a certain load (armature reaction) an encoderless tracking of the anisotropy does not work any more this effect appears around 2 to 3 times rated load with IPM motors around 5 to 6 times rated load with SMPM motors

98 Accuracy of the Rotor Position Identification under Load Conditions a) without load b) rated load (carrier frequency f c = 2 khz) why is the armature reaction so small???

99 Accuracy of the Rotor Position Identification under Load Conditions... because the usual rotor designs of servo motors (mechanical holes for inertia reduction) do not allow a load depending displacement of the main field why is the armature reaction so small???

100 Load Dependancy of Saturation Anisotropy (Armature Reaction) this is the effect reported by Bolognani cross section of a synchronous reluctance machine

101 Anisotropy of a Non-Compensated Machine this is the effect reported by Bolognani... the effect, however, appears later, because the coordinate system does not refer to the d axis any more, but to the orientation of main saturation cross section of a synchronous reluctance machine

102 Anisotropy of a Compensated Machine the orientation of the coordinate system can be re-adjusted to the d axis, (compensation of armature reaction) the Bolognani effect disappears!! cross section of a Jsynchronous reluctance machine

103 Another Problem : Trajectory Characteristics of Permanent Magnet Synchronous Machines under High Frequency Injection

104 single tooth (bobbin) windings cost reduction with respect to significant smaller end windings will replace distributed windings in synchronous machines disadvantage : magnetic field has non-sinusoidal distribution several maxima / zero crossings per period possible consequence : the tracking controller does not catch the position any more

105 Page 105 J consequence : the tracking controller does not catch the position any more because it cannot find a maximum or minimum q component of the high frequency current response

106 Summary high frequency schemes require a minimal magnetic anisotropy in the electrical machine the d-q-anisotropy is load dependant: 2-fold rated current in synchronous machines with buried magnets 6-fold rated current in synchronous machines with surface mounted magnets compensation of a misorientation might be necessary with respect to the load dependancy of the anisotropy high frequency schemes require a definite minimum or maximum of the anisotropy there are machines with a very complex magnetic structure

107 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 107

108 Further Research Activities Page 108 enabling encoderless control to work with more sophisticated motor designs how can the scheme be improved? encoderless control suffers under small detection signals (currents) can wavelet-based concepts improve anything? which motor designs support encoderless control, high frequency models for electrical machines are needed most well-known models consider the fundamental behaviour only

109 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 109

110 Saliency based Encoderless Predictive Torque Control without Signal Injection Overview Predictive Torque Control Saliency Tracking P. Landsmann, D. Paulus, P. Stolze and R. Kennel Technische Universitaet Muenchen Munich Germany Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

111 Basic Idea: A Predictive Torque Controller neglecting the saliency in the model causes a prediction error which contains the angle information Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

112 Predictive Torque Control Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

113 Predictive Torque Control Current and PM flux linkage from measurements Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

114 Predictive Torque Control Current and PM flux linkage from measurements 7 voltages vectors from inverter Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

115 Predictive Torque Control Current and PM flux linkage from measurements 7 voltages vectors from inverter prediction of current and respective torque Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

116 Predictive Torque Control Current and PM flux linkage from measurements 7 voltages vectors from inverter prediction of current and respective torque Overview Predictive Torque Control Saliency Tracking Selecting optimum of cost function Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

117 Predictive Torque Control Overview Predictive Torque Control Saliency Tracking Simulation Results Discrete model of the machine Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

118 Predictive Torque Control Overview Predictive Torque Control Saliency Tracking Simulation Results Discrete model of the machine Measurements Current prediction based on mean inverse inductance Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

119 Saliency Tracking Approach Predicted current progression Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

120 Saliency Tracking Approach Predicted current progression Overview Predictive Torque Control Real current progression Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

121 Saliency Tracking Approach Predicted current progression Overview Predictive Torque Control Real current progression Saliency Tracking Prediction error Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

122 Saliency Tracking Approach Measured prediction error Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

123 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

124 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

125 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

126 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

127 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

128 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

129 Saliency Tracking Approach Measured prediction error Overview Reconstructed prediction error Predictive Torque Control Saliency Tracking PLL controller input Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

130 Simulation Results for PMSM Simulation parameter of PMSM Overview Predictive Torque Control Saliency Tracking Speed controlled encoderless predictive torque control Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

131 Simulation Results for PMSM Speed controlled step response to rated speed very good dynamics in simulation Overview Predictive Torque Control dependency on torque gradients Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

132 Measurements with Reluctance Machine Data of transverse laminated RM Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

133 Measurements with Reluctance Machine Speed controlled step response to 160% rated speed Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

134 Measurements with Reluctance Machine Response to 66% rated torque load step at speed controlled standstill Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

135 Summary Proposed Scheme: Neglect the saliency in PTC equations Prediction error contains angle information Reconstruct Prediction Error using PLL angle Vectorproduct of both is PLL input Benefits: Saliency based: permanent operation at standstill No signal injection: operation at high speed as well as at standstill Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

136 Encoderless Control with Arbitrary Injection Limitations of HF Injection Methods - HF injection voltage margin limitation to medium and low speed - Restriction to rotating or alternating shape due to algorithmic reasons Meaning of Arbitrary - No physical necessity for injection shape - Basically any current ripple contains the saliency angle information - Finding a way to exploit this provides additional degrees of freedom

137 Speed Limitation Voltage hexagon in stator frame Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

138 Encoderless Control with Arbitrary Injection Limitations of HF Injection Methods - HF injection voltage margin limitation to medium and low speed usually the current ripple caused by the inverter switchings are sufficient to exploit the rotor position - Restriction to rotating or alternating shape due to algorithmic reasons Meaning of Arbitrary - No physical necessity for injection shape - Basically any current ripple contains the saliency angle information - Finding a way to exploit this provides additional degrees of freedom

139 PWM Pattern Utilization Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

140 Encoderless Control with Arbitrary Injection Limitations of HF Injection Methods usually the current ripple caused by the inverter switchings are sufficient to exploit the rotor position Meaning of Arbitrary - No physical necessity for injection shape - Basically any current ripple contains the saliency angle information if not any current ripple can eben be music!!! - Finding a way to exploit this provides additional degrees of freedom

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142 The Idea of Arbitrary Injection The Prediction Error Overview - Voltage applied to the machine Predictive Torque Control - Isotropic machine model used to predict current progression - Measured current progression Saliency Tracking Simulation Results Measurements Conclusion - The Prediction Error contains the saliency angle information Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

143 The Idea of Arbitrary Injection The Prediction Error Current progression Isotropic Model Overview Predictive Torque Control Salient Machine Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

144 The Idea of Arbitrary Injection Angle Estimation Equation Prediction Error Overview Scalar expression Predictive Torque Control Saliency Tracking Simulation Results The Angle Equation Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

145 Industrial Needs The proposed PTC (Predictive Torque Control) method single scheme for wide speed range (no phase over) The sensorless control scheme presented here does not need additional voltage measurement devices - neither on the machine/motor side nor on the line side no additional noise (except usual noise by inverter supply) As long as there is a detectable saliency? insensitivity with respect to parameter variations works from standstill to maximum speed PTC is very robust to variations of the motor parameters further research to be done!! Page 145

146 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 146

147 Further Research Activities enabling encoderless control to work with more sophisticated motor designs how can the schemes be improved? encoderless control suffers under small detection signals (currents) can wavelet-based concepts improve anything? further research to be done!! which motor designs support encoderless control, high frequency models for electrical machines are needed most well-known models consider the fundamental behaviour only

148 Extended Methods example: current oversampling based derivative calculation Overview Predictive Torque Control Saliency Tracking Simulation Results Measurements Conclusion Institute for Electrical Drive Systems & Power Electronics Technische Universität München Arcisstr. 21, D Munich - peter.landsmann@tum.de

149 Sensorless (Encoderless) Motor Drives introduction fundamental model methods high frequency injection methods encoderless control of synchronous machines machine response on high frequency injection voltages tracking of magnetic saliencies / anisotropies practical results experiences with industrial drives experiences with different motor designs further developments... what about predictive encoderless control?... what about wavelet technologies? conclusions Page 149

150 Actual EAL Activities encoderless control of more types of permanent magnet synchronous machines was successfully implemented in several industrial servo drives we can proceed with more collaboration partners and/or applications encoderless control of synchronous reluctance machines is investigated in collaboration with our partner University of Stellenbosch (South Africa) final results are available a project on encoderless control of induction machines funding is granted and project start was in January 2013 first results are expected after 2 3 years a project on encoderless control (of induction machines) with current derivation sensors funding is granted and project start is in August 2013 first results are expected after 1 2 years a project on predictive encoderless control funding is granted and project start is in second half of 2013 first results are expected after 1 2 years

151 Thank you!!!