GB2600688A - Method of accurately determining angular rotor position from a raw signal - Google Patents
Method of accurately determining angular rotor position from a raw signal Download PDFInfo
- Publication number
- GB2600688A GB2600688A GB2017181.5A GB202017181A GB2600688A GB 2600688 A GB2600688 A GB 2600688A GB 202017181 A GB202017181 A GB 202017181A GB 2600688 A GB2600688 A GB 2600688A
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- GB
- United Kingdom
- Prior art keywords
- angle
- value
- determined
- raw
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/185—Circuit arrangements for detecting position without separate position detecting elements using inductance sensing, e.g. pulse excitation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
- G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
- G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
- G01D5/2046—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by a movable ferromagnetic element, e.g. a core
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/022—Synchronous motors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2203/00—Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
- H02P2203/01—Motor rotor position determination based on the detected or calculated phase inductance, e.g. for a Switched Reluctance Motor
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Of Electric Motors In General (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
A refined angular position of a rotor of an electric motor is determined from a raw signal. The method comprises: providing a raw signal indicative of raw angle of the rotor Angle_raw 10; computing a signal indicative of the change of angle Angle_delta 13 over a sample time interval; processing said signal to provide a filtered signal indicative of angular change Angle_delta_filt 15 over said time interval; and determining a signal indicative of refined filtered angle Angle_filt 18* by adding the value of the refined filtered angle computed at a previous sample timepoint to the determined filtered signal, characterized in additionally adding an angle compensation Angle_comp 21 thereto. The method may be used to control an electric motor in an electric vehicle.
Description
METHOD OF ACCURATELY DETERMINING ANGULAR ROTOR POSITION FROM A RAW SIGNAL
TECHNICAL FIELD
This relates to electric motors arid to a method and system of accurately determining the angular rotor position of an electric motor from a raw sensor signal indicative of (angular) rotor position It has particular but not exclusive application to motors for electric vehicles.
BACKGROUND OF THE INVENTION
Many vehicle electric motors are equipped with sensors to provide angular displacement information of the rotor such as a double inductive position sensor that provide analog sine and cosine signals corresponding to the rotor position.
These analog signals are e.g. sampled by the ECU every 100us to compute the actual rotor position/speed.
An e.g. inductive position sensor used on a power electronics application typically returns two analogue voltages which correspond to sine and cosine value of the rotor position (angle). In the prior art, these two voltages are normalized (resealed between -1 and 1) and filtered using ATO (Angle Tracking Observer) methodology.
The problem associated with this is the fact that the 3'd order Angle Tracking Observer (ATO) is not very stable at high speed and it needs lot of CPU resources.
It is an object of the invention to overcome these problems.
SUMMARY OF THE INVENTION
In one aspect is provided a method of determining a refined angular position of a rotor of an electric motor comprising the steps of: a) providing, in respect of a rotating electric motor rotor, a raw signal indicative of raw angle of the rotor (Angle raw); b) from step a), computing a signal indicative of the change of angle ((Angle delta) over a sample time interval; c) processing said signal from b); wherein said processing includes a filtering step, to provide a filtered signal indicative of angular change (Angle delta_filt) over said time interval; d) determining a signal indicative of refined filtered angle (Angle fill) by adding the value of the refined filtered angle computed at the previous sample timepoint to the value of the signal determined from step c), characterized in additionally adding an angle compensation (signal) value (Angle comp) thereto.
Said refined filtered angle at timepoint of sample n may be computed at step d) from the following equation: Angle_filt" = Angle_deltaf Wit+ Angle_comp where Angle_filtn_i: the previous sample value of the filtered angle; n representing an integer of the sample; Angle_deltaf i1t: is, the angle difference between two consecutive samples of Angle raw (Angle raw "-Angle raw "4) from step c); Angle_comp: is an angle/drift compensation value is computed based on the difference (Angle error) between raw angle of step a) and refined filtered angle determined at step d) Step b) may comprise determining the value of the signal of raw angle at first/current sample timepoint (tn))and the value of the signal of raw angle at a second/previous sampled time point (tn_1), said timepoints separated by a sample time interval; and determining the difference (Angle delta) therebetween. 3'
Said compensation angle value may be determined by determining an angle error (Angle error), based on signals from step a) and value (Angle fill determined at step d).
Said compensation angle value may be determined by determining an angle error (Angle error), based on the difference between signals from step a) and a time delayed value of the value Angle fill determined at step d).
Said time delayed value of the value Angle flit determined at step d) may be time delayed by a sample or processing interval time Said compensation angle value may be determined by determining an angle error (Angle error), based on the difference between signal from step a) and the value Angle flit Said compensation angle value may be determined by determining an angle error (Angle error), based on the difference between signal value from step a) and a time delayed value Angle Jilt, said time delay being equal to a processing or sampling time.
Said angle compensation value may be determined based a value obtained by applying a gain to the determined angle error (Angle error) Said angle compensation value may be determined based a value obtained by integrating the angle error (Angle error) signal value Said angle compensation value may be determined based on a value obtained by integrating the angle error (Angle error) as well as on a value obtained by applying a gain to the determined an angle error (Angle error).
The terms "signal and "value" can be regarded as interchangeable Sample interval" means a sample time interval or a processing time interval.
That is e.g. step b) comprises determining the value of the signal of raw angle at first and second time points separated by a sample or computational time interval; and determining the difference (Angle delta) 13 therebetween. The term "sample timepoint" can be considered a "computational timepoint"
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is now described by way of example with reference to the accompanying drawings in which: Figure 1 shows a rotor position sensor system and the resulting signals therefrom; Figure 2 shows an alternative simple prior art system/method, where a raw signal indicative of rotor angular position (Angle ran) of an electric motor is used to determine change in angle (Angle delta); Figure 3 illustrates an example of the invention
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows a rotor position sensor system on the left and on the right the resulting signals therefrom. So figure 1 shows a diagram of an inductive motor position sensor 1, showing rotor 2, stator 3, induction 4, transmitter coil 5, receiver coil 6 and electronics (chip) 7. On the right is shown the signals generated from such a sensor and from these a (raw) angle signal may be obtained.
In prior art systems a 3rd order angle tracking observer (ATO) is used to obtain filtered position and speed from the raw angle. The disadvantages have been discussed above.
Figure 2 shows an alternative simple prior art system/method, where a raw signal indicative of rotor angular position (Angle rtm) of an electric motor is used to determine change in angle (Angle delta) over a time interval i.e. the angular difference between e.g. the present and the previous raw angle samples; i.e separated by a sampling time interval.
The block diagram shows this is performed by subtracting a time delayed value of raw angle 11 from the raw angle 10 at block 12 to give a value of the change in angle (Angle delta) 13.
Control blocks 8 and 9 (1/Z) represents the time delay.
A basic low pass filter 14 is used to the filter the delta angle (Angle delta)13 to provide filtered signal 15 (Angle delta.filt).
A final filtered angular position (Angle.filt) 18 is obtained by summing the previous (sample) filtered angular position sample 16 (obtained by applying by applying a time delay (1/Z)) at 9) and the filtered angle delta 15 at 17. AGin the time delay is the sampling or processing time interval.
During motor acceleration/deceleration, the angle delta lag (induced by the low pass filter) causes a position drift. This drift is cumulated on each filtered angle computation and can reach up to 20° at the end of speed ramp-up.
Invention The problem of calibration issue, accuracy and CPU load are solved by filtering the delta position and applying a drift correction (angle compensation) to compensate filter lag while high acceleration, In an example, the filtered angular position Angle _f iltnis computed using the following formula: Angle _f ilt, = Angle _f + Angle _delta _f ilt, + Drift Angie _comp where: : the previous value (sample value) of the filtered angle; n representing an integer of the sample number; Angle_delta_filtn: as before i.e. the angle difference between two consecutive samples of Angle raw (Angle raw n -Angle raw n_l) after being further filtered using low-pass filter. Again a represents and integer value representing the sample number.
Drift/Angle _comp (Angle comp): the drift/angle compensation is computed based on the difference (Angle error) between raw and filtered angle. This difference may be preferably learnt (e.g using an integrator) to compensate growing drift. In parallel, a fast proportional correction may be is applied.
So in other words, a drift or angle compensation correction value is (Angle comp) is determined and applied to the system of figure 2 to obtain a more accurate value of the filtered angle (Anglejill) So, in order to avoid the error accumulation, the drift may be learned by using an integrator and summed to the filtered angle delta. This correction centers the angle error around zero and what remains is the noise that to be eliminated, Figure 3 shows an example of the invention. It includes the functional components of the prior art methodology/system as in figure 2, with like reference numerals representing the same, but also includes a compensation loop(s) designated by the dotted line 20.
So as before a raw signal indicative of rotor angular position (Angle raw) of an electric motor is used to determine change in angle (Angle delta) which is e.g. the difference between e.g. the present and previous raw angle sample vlaues. This is implemented as described above with reference to figure 2.
So the block diagram shows this is performed by subtracting a time delayed value 11 of raw angle from the raw angle at 10. Control block 8 (1 /Z) represents a time delay, which may be the sample/processing interval A basic low pass filter 14 is used to the filter the delta angle (Angle delta) 13 to provide Angle delta.fill 15.
A final filtered angular position is obtained by summing the previous filtered angle position (Angle_filt) 18* sample designated 16 (by applying a time delay 9 (1/Z)) and the filtered angle delta 15 at 17; however in addition, at 17 there is a drift or angle correction/compensation (Angle comp) applied.
So a correction value (Angle comp) 21 is added to the Angle delta.filt 15 and time delayed (sample) of Angle jilt) 16 to provide the value of Angle jilt 18* and the correction value is determined as follows-A time delayed value (signal) 22 of filtered angle (Angle _fill) 18* is provided by applying time delay block 30, represented again by 1/Z, and is then subtracted from the raw angle 10 at block 23 to produce an angle error (Angle error) signal 24. The time delay may be equal to the sample interval or the processing time. It may be tuned to an optimum depending on processing time. The time delay is preferred to overcome problems regarding algebraic loops, and preferably equal also to the sample time above..
A gain is then applied (via block 25) to this Angle error signal, to provide the signal/value 26. It should be noted that the gain may be any value including 1 no gain. In addition or alternatively the value of Angle error is input to an integrator (27) i.e. the signal is integrated to provide a signal 28. Before being input to the integrator there may optionally be applied an additional gain 40 in this path also.
An angle compensation value (Angle comp) 21 computed can be the value of the signal 26 and/or the value of the signal 28. Preferably the angle compensation value is determined by adding the signals 26 and/or 28 (components), i.e. Angle comp 21 is determined by adding both the value of 26 and 28.
The advantages of this invention compared to the prior art are: the speed and position calculation robustness by filtering the delta angle inconsistency; and the 30 reduction of the CPU load compared to prior art methodology ATO method.
Claims (11)
- CLAIMS1. A method of determining a refined angular position (18*) of a rotor of an electric motor comprising the steps of: a) providing, in respect of a rotating electric motor rotor, a raw signal indicative of raw angle of the rotor (Angle raw) (10); b) from step a), computing a signal indicative of the change of angle ((Angle della) (13) over a sample time interval; c) processing said signal from b); wherein said processing includes a filtering step, to provide a filtered signal indicative of angular change (Angle deltajilt) over said time interval (15); d) determining a signal indicative of refined filtered angle (Angle_fill) (18*) by adding the value of the refined filtered angle computed (18*) at the previous sample timepoint to the value of the signal determined from step c), characterized in additionally adding an angle compensation (signal) value (21) (Angle comp) thereto.
- 2. A method as claimed in claim 1 where said refined filtered angle (18*) at timepoint of sample n is computed at step d) from the following equation Angle_f ilt" = Anglef + Angle _deltaf ilti, + Angle_comp where Angle _f: the previous sample value of the filtered angle; n representing an integer of the sample; Angle_delta_f LIt11: is, the angle difference between two consecutive samples of Angle raw (Angle raw,, Angle raw "_1) from step c); Angle_comp: is an angle/drift compensation value is computed based on the difference (Angle error) between raw angle of step a) and refined filtered angle determined at step d).
- 3. A method as claimed in claim 1 or 2 wherein step b) comprises determining the value of the signal of raw angle at first/current sample timepoint (t4)and the value of the signal of raw angle at a second/previous sampled time point (tri.i), said timepoints separated by a sample time interval; and determining the difference (Angle delta,) (13) therebetween.
- 4 A method as claimed in steps 1 to 3 wherein said compensation angle value (21) is determined by determining an angle error (Angle error), based on signals from step a) and value (18*) Angle jilt determined at step d).
- A method as claimed in steps 1 to 4 wherein said compensation angle value (21) is determined by determining an angle error (Angle error), based on the difference between signals from step a) and a time delayed value of the value (18*) Angle jilt determined at step d)
- 6. A method as claimed in claim 5 wherein said time delayed value of the value (18*) Angle jilt determined at step d) is time delayed by a sample or processing interval time.
- 7. A method as claimed in steps 1 to 6 wherein said compensation angle value (21) is determined by determining an angle error (Angle error), based on the difference between signal from step a) and the value (18*) Angle jilt
- 8. A method as claimed in steps 1 to 7 wherein said compensation angle value (21) is determined by determining an angle error (Angle error), based on the difference between signal value from step a) and a time delayed value (18*) Angle jilt, said time delay being equal to a processing or sampling time.
- 9. A method as claimed in claim 7 or 8 wherein said angle compensation value (21) is determined based a value (26) obtained by applying a gain to the determined angle error (Angle mor)(24).
- 10. A method as claimed in claim 7 to 9 wherein said angle compensation value (21) is determined based a value (28) obtained by integrating the angle error (Angle error) signal value (24) .
- 11. A method as claimed in claim 7 to 104 wherein said angle compensation value (2)1 is determined based on a value (28) obtained by integrating the angle error (Angle error) as well as on a value (26) obtained by applying a gain to the determined an angle error (Angle error).
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2017181.5A GB2600688B (en) | 2020-10-29 | 2020-10-29 | Method of accurately determining angular rotor position from a raw signal |
PCT/EP2021/075372 WO2022089829A1 (en) | 2020-10-29 | 2021-09-15 | Method of accurately determining angular rotor position from a raw signal |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2017181.5A GB2600688B (en) | 2020-10-29 | 2020-10-29 | Method of accurately determining angular rotor position from a raw signal |
Publications (3)
Publication Number | Publication Date |
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GB202017181D0 GB202017181D0 (en) | 2020-12-16 |
GB2600688A true GB2600688A (en) | 2022-05-11 |
GB2600688B GB2600688B (en) | 2023-05-17 |
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Family Applications (1)
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GB2017181.5A Active GB2600688B (en) | 2020-10-29 | 2020-10-29 | Method of accurately determining angular rotor position from a raw signal |
Country Status (2)
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GB (1) | GB2600688B (en) |
WO (1) | WO2022089829A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010239698A (en) * | 2009-03-30 | 2010-10-21 | Aisin Seiki Co Ltd | Ac motor controller |
US20160197568A1 (en) * | 2013-07-23 | 2016-07-07 | Korea Institute Of Ocean Science & Technology | Driving apparatus for motor using time delay compensation method of current detecting sensor combined with filter |
CN108282124A (en) * | 2017-12-20 | 2018-07-13 | 上海辛格林纳新时达电机有限公司 | The rotor position angle compensation method of motor vector controlled |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101171497A (en) * | 2005-05-11 | 2008-04-30 | 丰田自动车株式会社 | Rotational position detector, and rotary electrical equipment driving unit provided therewith |
WO2007105366A1 (en) * | 2006-03-14 | 2007-09-20 | Ntn Corporation | Rotation angle detector and bearing with rotation detector |
DE102013224243A1 (en) * | 2013-11-27 | 2015-05-28 | Robert Bosch Gmbh | Method and device for determining a position indication of a rotor of an electrical machine |
-
2020
- 2020-10-29 GB GB2017181.5A patent/GB2600688B/en active Active
-
2021
- 2021-09-15 WO PCT/EP2021/075372 patent/WO2022089829A1/en active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010239698A (en) * | 2009-03-30 | 2010-10-21 | Aisin Seiki Co Ltd | Ac motor controller |
US20160197568A1 (en) * | 2013-07-23 | 2016-07-07 | Korea Institute Of Ocean Science & Technology | Driving apparatus for motor using time delay compensation method of current detecting sensor combined with filter |
CN108282124A (en) * | 2017-12-20 | 2018-07-13 | 上海辛格林纳新时达电机有限公司 | The rotor position angle compensation method of motor vector controlled |
Also Published As
Publication number | Publication date |
---|---|
GB202017181D0 (en) | 2020-12-16 |
WO2022089829A1 (en) | 2022-05-05 |
GB2600688B (en) | 2023-05-17 |
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