DE102009028590A1 - Electronically commutated electric motor with a rotor position prediction and method - Google Patents

Abstract

The invention relates to an electronically commutated electric motor. The electronically commutated electric motor has a stator and a rotor, in particular a permanent magnet. The electric motor also has a control unit which is operatively connected to the stator and is designed to generate control signals for commutating the stator in such a way that the stator can generate a rotating magnetic field for rotating the rotor. The electric motor also has at least one rotor position sensor which is designed to detect a rotor position, in particular an angular position, of the rotor and to generate a rotor position signal representing the rotor position. The control unit is designed to generate the control signals as a function of the rotor position signal. According to the invention, the control unit is designed to sample and quantize the rotor position signal and to generate a digital prediction rotor position signal. The digital prediction rotor position signal forms a temporal data stream which corresponds to the sampled and quantized rotor position signal and comprises at least one or a plurality of future rotor position values which go beyond the rotor position signal in time.

Description

State of the art

The The invention relates to an electronically commutated electric motor. The electronically commutated electric motor has a stator and a particular permanent magnetic trained rotor. The electric motor also has a control unit, which with the Stator is operatively connected and formed, control signals for commutation of the stator to produce such that the stator is a magnetic Rotary field for rotating the rotor can produce. The electric motor also has at least one rotor position sensor, which is formed is a rotor position, in particular an angular position of the rotor to capture and a rotor position representing To generate rotor position signal. The control unit is designed the control signals in response to the rotor position signal to create.

From the DE 103 57 504 A1 An electric motor is known in which a rotor position of a rotor is determined by means of a sensor and an oscillator synchronized to the output signal of the sensor. In this case, the rotor position is derived between detection positions of the output signal by means of a vibration of the oscillator.

at fast-rotating electronically commutated electric motors the problem that during operation of the electric motor the rotor position detection is performed at a high detection frequency must be if more frequent during a rotor rotation Change a Kommutierungsmusters to take place. The control unit The electric motor must then have a correspondingly high computing capacity exhibit.

Disclosure of the invention

According to the invention the control unit of the electronically commutated electric motor of formed the aforementioned type, to sample the rotor position signal and to quantize, and a digital prediction rotor position signal to create. The digital prediction rotor position signal forms a temporal data stream which is the sampled and quantized Rotor position signal corresponds and at least one or a plurality of future, via the rotor position signal in time outgoing rotor position values. By the way formed prediction rotor position signal can be advantageous the rotor position for a current rotor position, or for future rotor positions for commutation of the electric motor are available. Further advantageous can the so predicted rotor position for commutation of the electric motor for Be available before the rotor position sensor, in particular an angle sensor, after conversion of an example analog rotor position signal in a digital rotor position signal, the thus converted rotor position signal can provide for further signal processing.

Of the Rotor position sensor is preferably an angle sensor. The angle sensor is for example a Giant Magneto Resistive Sensor (GMR sensor) or an anisotropic magneto-resistive sensor (AMR sensor). In In another embodiment, the electric motor, for example, a Plurality of Hall sensors, which are each formed to generate an analog rotor position signal. Preferably, the Angle sensor, in particular the GMR sensor or AMR sensor, designed, to generate a continuous time, analog rotor position signal. An angular resolution of the angle sensor is then through a Sampling rate of the analog rotor position signal analog-to-digital converting Analog-to-digital converter determines.

In A preferred embodiment is the control unit formed, in particular digital prediction rotor position signal as a function of others, by means of the rotor position sensor detected rotor positions in particular according to a principle Correct first-in-first-out (FIFO). For this purpose, the prediction rotor position signal, for example formed by a predetermined number of rotor position values with the rotor position values with each new one from the angle sensor further preferably additionally from an analog-to-digital converter converted - rotor position value according to the FIFO principle to be updated. This can advantageously the commutation of the Electric motor also with non-stationary motion patterns respectively. For example, the control unit may during a rotor revolution a variety of mutually different Kommutierungsmuster apply pressure to the stator.

In A preferred embodiment is the control unit formed, the digital prediction rotor position signal by means of an approximation function as a function of Rotor position signal as to be approximated output function produce. As a result, advantageously by means of the rotor position sensor generated rotor position signal for future rotor positions be estimated advantageous.

Prefers the approximation function is a polynomial, in particular at least second degree or exactly second or third degree. Further advantageous Embodiments for an approximation function are a spline function or an exponential function.

The control unit has in an advantageous Embodiment, a timer, and is adapted to commutate the stator, in particular by means of the Kommutierungsmusters, depending on a time signal generated by the timer and in dependence of the prediction rotor position signal. As a result, the stator can advantageously be commutated to a time determined in accordance with the approximation function after a time signal generated by the timer, for example a time interval thus formed, has elapsed.

Prefers For example, the control unit can be designed to control the commutation time by means of linear interpolation between two in particular successive following, preferably future, rotor position values to determine the prediction rotor position signal.

The The invention also relates to a method for operating an electronic commutated electric motor, in particular of the electric motor described above. In the method, by means of a rotor position sensor Rotor position detected and a rotor position corresponding rotor position signal generated. Furthermore, in the method, the rotor position signal is preferred sampled and quantized, and a particular digital, a temporal Data stream forming prediction rotor position signal generated. The prediction rotor position signal represents the sampled and quantized rotor position signal and at least one, or a plurality of future, over the rotor position signal temporally reaching rotor position values.

In A preferred embodiment of the method is the digital prediction rotor position signal in dependence corrected by further, detected by the rotor position sensor rotor positions.

In an advantageous embodiment of the method the digital prediction rotor position signal is passed through Forming an approximation function as a function of Rotor position signal generated as an output function. The output function is while the function to be approximated, which support points to generate the approximation function. This can the prediction rotor position signal also over one through the support points, for example by means of Rotor position signal formed - or generated from this area Be extrapolated. The approximation function is preferred a second or third degree polynomial function.

In a preferred embodiment of the method takes place depending on the prediction rotor position signal after a time interval, commutation of the stator, wherein the sequence corresponds to a predetermined commutation time. Preferably, the commutation is carried out by means of at least one, preferably predetermined commutation pattern. This can cause the commutation advantageously already before the presence of one by means of the rotor position sensor generated rotor position value done.

at the process is preferably the expiration of the time interval means Linear interpolation between two rotor position values of the prediction rotor position signal determined. This allows the future rotor position value can advantageously be determined quickly. The control unit points in this embodiment for the linear interpolation only adders as arithmetic operators on. It is also conceivable to determine of the future rotor position value in dependence the approximation function. The necessary multiplications can be advantageous by a correspondingly fast computing unit respectively.

The Control unit may for example be a microprocessor, a microcontroller or an FPGA (FPGA = Field Programmable Gate Array), or an ASIC (ASIC = Application-Specific-Integrated-Circuit). The control unit is controlled, for example, by a control program which is stored on a disk and together with the Disk forms a computer program product.

The The invention also relates to a control unit according to above-described type for an electric motor of the above Art. The control unit then has no rotor and no stator on and is formed connected to a stator of an electric motor to become.

The Invention will now be described below with reference to figures and others Embodiments described. Further advantageous Embodiment variants result from the previously described Characteristics, as well as the features specified in the figure description, and those specified in the dependent claims Features.

1 shows an embodiment of an electronically commutated electric motor with the control unit according to the invention;

2 shows a method for operating the in 1 shown electric motor;

3 shows a diagram showing the operation of the in 1 shown electric motor and the in 2 illustrated method illustrates.

1 shows - schematically - a Ausfüh Example of an electronically commutated electric motor 1 , The electric motor 1 has a stator 10 with three stator coils, namely a stator coil 12 , a stator coil 14 and a stator coil 16 on. The stator 10 also has an angle sensor which can generate an example analog rotor position signal. The angle sensor 18 is formed, a rotor position of a rotor 11 of the electric motor 1 capture. The angle sensor 18 , is by means of a connection 50 with a control unit 30 of the electric motor 1 connected. The control unit 30 has an analog-to-digital converter 27 on which input side with the connection 50 and so with the angle sensor 18 connected is. An angular resolution of the angle sensor is determined by a sampling rate of the analog-to-digital converter in the case of the analog, in particular time-continuously formed rotor position signal. The analog-to-digital converter 27 is on the output side via a connecting line 54 with a polynomial generator 29 connected.

The analog-to-digital converter 27 is formed, the input side via the connection 50 to sample received rotor position signal and to generate a temporal sequence of samples, which each represent an amplitude value of the rotor position signal. The analog-to-digital converter 27 is on the output side via a connecting line 54 with a polynomial generator 29 connected. The polynomial generator 29 is formed, depending on the over the connecting line 54 received, - the rotor position of the rotor 11 representing sampling values to produce an approximation function which at least approximately represents a curve represented locally by the samples.

Of the Polynomial generator is preferably formed, the approximation function using a method of least square error.

The Approximation function is preferably a polynomial, in particular a Second or third degree polynomial. It is also conceivable - in particular depending on the required computing time of the Polynomial generator - a polynomial more than third degree.

The polynomial generator 29 is designed to determine polynomial coefficients of the previously determined approximation function, in particular of the polynomial, and these on the output side via a connecting line 56 to a coefficient memory 32 issue. This is indicated by the polynomial generator 29 For example, for each polynomial coefficient on a FIR filter, in this embodiment, three exemplary FIR filters 36 . 38 and 39 , The coefficient memory 32 is formed by the polynomial generator 29 keep polynomial coefficients in stock. The coefficient memory 32 is on the output side via a connecting line 58 with a predictor 34 connected. The predictor 34 is formed in the coefficient memory 32 stored coefficients over the connecting line 58 to read, and to generate a temporally successive, representing rotor position values data stream and this output side via the connecting line 60 to a control unit 42 issue. The data stream comprises temporally successive future rotor position values-shown in dotted lines in this exemplary embodiment-which are each a future, from the angle sensor 18 represent not yet detected rotor position. The data stream in this embodiment forms the previously mentioned prediction rotor position signal.

mit

y_e,n(Δn)

= Prädiktorpolynom als Approximationsfunktion;

n

= Abtastwert, ganze Zahl oder Zahl < 1;

T_a

= Abtastperiode;

g

= Grad des Polynoms;

a

= Polynomkoeffizient.

The approximation function, in particular the polynomial, can be formed, for example, as follows:

With

y _{e, n} (Δn)

= Predictor polynomial as approximation function;

n

= Sample, integer or number <1;

T _a

= Sampling period;

G

= Degree of the polynomial;

a

= Polynomial coefficient.

The control unit 42 is with a timer 40 connected and is formed, at least in dependence on the over the connecting line 60 received prediction rotor position signal to the stator 10 to commute.

The control unit 42 is the output side via a connection 53 with a power output stage 25 of the electric motor 1 connected. The control unit 42 is trained, the power output stage 25 for generating a rotating magnetic field by means of the stator coils 12 . 14 and 16 head for. The power output stage 25 is on the output side via a connection 52 with the stator 10 , and there with the stator coils 12 . 14 and 16 connected. The control unit 42 is formed depending on the timer 40 received, in particular high-resolution time signal, the commutation times for commutating the stator 10 to be determined exactly.

The polynomial generator 29 may be advantageous for each polynomial coefficient in the coefficient memory 32 stock polynomial coefficients have an FIR (Finite Impulse Response) filter.

The control unit 42 is also on the input side via the connecting line 54 with the analogue digi talwandler 27 and may receive the digitized rotor position signal from the analog-to-digital converter.

The control unit 42 is trained by the predictor 34 calculated rotor position values by means of linear interpolation between two successive prediction values to determine a Kommutierungszeitpunkt for commutating the stator coils and the power output stage 35 to control the commutation of the stator coils accordingly.

In another embodiment, the polynomial generator is 29 and the predictor 34 formed jointly by a plurality of FIR filters, wherein for each, in particular future, Rotorpositonswert a FIR filter is formed. As a result, for example, two FIR filters are available for two future rotor position values. The coefficient memory 32 can be omitted in this embodiment.

2 shows an embodiment of a method for commutating an electronically commutated electric motor. The method is in one step 70 detects a rotor position of a rotor of the electronically commutated electric motor, in particular by means of an angle sensor and generates a rotor position signal which represents at least one rotor position of the rotor. In one step 72 the rotor position signal is digitized by means of an analog-to-digital converter and a digitized rotor position signal is generated. In one step 74 In dependence on the digitized rotor position signal, a polynomial is generated which approximates the digitized rotor position values at least approximately. In one step 76 polynomial coefficients which represent the previously formed polynomial are buffered. In one step 78 a polynomial is formed by means of a predictor as a function of the polynomial coefficients previously generated, and a data stream is generated depending on the polynomial comprising rotor position values in a time range in which the rotor position values detected by the angle sensor lie, and in addition has future rotor position values which are from the angle sensor have not yet been detected and / or by that of the analog-to-digital converter 24 generated signal are not yet represented. In one step 80 a commutation pattern is selected as a function of the data stream, for example from a plurality of commutation patterns held in stock, and in one step 82 the stator is energized with the Kommutuierungsmuster.

3 shows a diagram 90 , The diagram 90 has a timeline 91 and an amplitude axis 92 on.

The diagram 90 shows a curve 95 which samples 101 . 102 . 104 . 106 . 108 . 110 and 112 connects with each other. The curve 95 corresponds to a polynomial which, for example, by means of in 1 shown polynomial generator 29 has been generated, and which represents a rotor position course. The polynomial 95 is a third degree polynomial in this embodiment.

Shown are also rotor position values 101 . 103 . 105 . 107 . 109 . 111 and 113 ,

The rotor position value 101 is from the angle sensor, such as the one in 1 illustrated angle sensor 18 been recorded.

Also shown are a time interval 96 and a time interval 98 , The time interval 96 represents a sample period of an analog-to-digital converter, such as the one in FIG 1 illustrated analog-to-digital converter 27 ,

The rotor position values 100 . 102 . 104 . 106 . 108 110 and 112 are respectively to previous and subsequent rotor position values through the time interval 96 spaced.

The rotor position value 101 follows after the time interval 98 to the rotor position value 100 , The rotor position value 103 follows after the time interval 98 to the rotor position value 102 , The time interval 98 represents a computing time that the analog-to-digital converter requires to perform the digitization of the rotor position signals sent by the angle sensor.

The control unit - for example, the control unit 30 in 1 Thus, for further signal processing and for controlling the commutation times, the rotor position signals detected by the angle sensor are digitized later-in this example by the time interval 98 delayed - available when they have been detected by the angle sensor. Shown are the commutation times 115 and 117 , The commutation time 115 is from the rotor position value 102 around the time interval 99 spaced. The time interval 99 is shorter than the time interval 98 so that the commutation time 115 after the presence of the digital rotor position value 103 - Which the rotor position of the rotor position value 102 corresponds - takes place.

By generating the predictor polynomial and predicting from the future rotor position values derived from the Angle sensor have not yet been detected, can advantageously a Sampling frequency for detecting a rotor position of the rotor lower than without prediction using the predictor polynomial.

For example, if the rotor position values 100 . 102 . 104 and 106 have been detected by the angle sensor, so can the rotor position value 108 , the rotor position value 110 and the rotor position value 112 be generated by means of the predictor polynomial.

In a further course of the method for commutating the electric motor, the control unit, for example, the control unit 42 in 1 , the rotor position values generated by the predictor 108 . 110 and 112 with the rotor position values detected by the angle sensor 109 . 111 respectively 113 compare and use to form another polynomial curve of the predictor polynomial.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10357504 A1 [0002]

Claims (12)

Electronically commutated electric motor ( 1 ), with a stator ( 10 ) and a particular permanent magnetic rotor ( 11 ), and a control unit ( 30 ), which is operatively connected to the stator and formed, control signals for commutating the stator ( 10 . 12 . 14 . 16 ) such that the stator ( 10 . 12 . 14 . 16 ) a magnetic rotating field for rotating the rotor ( 11 ) and the electric motor ( 1 ) at least one rotor position sensor ( 18 ), which is formed, a rotor position of the rotor ( 11 ) and to generate a rotor position signal representative of the rotor position, and the control unit ( 30 ) is adapted to generate the control signals in dependence on the rotor position signal, characterized in that the control unit ( 30 ) is adapted to sample and quantize the rotor position signal ( 27 ), and a digital prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) which forms a temporal data stream that corresponds to the sampled and quantized rotor position signal and at least one or a plurality of future rotor position values that are beyond the rotor position signal (FIG. 108 . 110 . 112 ). Electric motor ( 1 ) according to claim 1, characterized in that the control unit ( 30 ), the digital prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) in dependence on further, by means of the rotor position sensor ( 18 ) corrected rotor positions. Electric motor ( 1 ) according to claim 2, characterized in that the control unit ( 30 ), the digital prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) by means of an approximation function as a function of the rotor position signal ( 100 . 102 . 104 . 106 ) as output function. Electric motor ( 1 ) according to claim 3, characterized in that the approximation function is a polynomial, in particular of at least the second degree. Electric motor ( 1 ) according to one of the preceding claims, characterized in that the control unit ( 30 ) a timer ( 40 ), and is formed, depending on one of the timer ( 40 ) and in dependence of the prediction rotor position signal ( 95 ) to commute the stator ( 115 . 117 ), Method for operating an electronically commutated electric motor having a rotor, in particular according to one of claims 1 to 5, in which by means of a rotor position sensor ( 18 ) a rotor position of a rotor ( 11 ) and a rotor position signal corresponding to the rotor position is generated, and in which the rotor position signal is sampled and quantized, and a digital, temporal data stream forming prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) representing the sampled and quantized rotor position signal and comprising at least one or a plurality of future rotor position values beyond the rotor position signal. Method according to Claim 6, in which the digital prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) is corrected in dependence on further, detected by the rotor position sensor rotor positions according to a first-in-first-out principle. Method according to claim 6 or 7, characterized that the digital prediction rotor position signal by Forming an approximation function as a function of Rotor position signal is generated as an output function. Method according to one of claims 6 to 8, characterized in that the approximation function a Polynomial function is in particular at least second degree. Method according to one of claims 6 to 8, characterized in that the approximation function a Spline function is. Method according to one of claims 6 to 10, characterized in that in dependence of the prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) after a time interval, wherein the sequence corresponds to a predetermined commutation time, a commutation ( 115 . 117 ) of the stator, preferably by means of a commutation pattern. A method according to claim 11, characterized in that the passage of the time interval by means of linear interpolation between two rotor position values of the prediction rotor position signal ( 95 . 100 . 102 . 104 . 106 . 108 . 110 . 112 ) is determined.

Images