CN112904261B - Harmonic calibration system and method, error harmonic component coefficient calculation system and method - Google Patents
Harmonic calibration system and method, error harmonic component coefficient calculation system and method Download PDFInfo
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Abstract
The invention discloses a harmonic calibration system and method, and an error harmonic component coefficient calculation system and method, wherein the harmonic calibration system comprises a differentiator, a first mixer, a second mixer, a first integral unit, a second integral unit, a sine harmonic coefficient acquisition module, a cosine harmonic coefficient acquisition module and a harmonic calibration module; the harmonic calibration module is respectively connected with the sine harmonic coefficient acquisition module and the cosine harmonic coefficient acquisition module, eliminates error harmonic components from the original angle signal, and obtains a calibrated angle signal. The harmonic calibration system and method and the error harmonic component coefficient calculation system and method provided by the invention can eliminate various harmonic errors and improve the detection accuracy.
Description
Technical Field
The invention belongs to the technical field of microelectronics, relates to a harmonic calibration system, and in particular relates to a harmonic calibration system and method for an angle sensor, and an error harmonic component coefficient calculation system and method.
Background
The magnetic sensor is a device for detecting corresponding physical quantities by converting magnetic property changes of sensitive elements caused by external factors such as magnetic fields, currents, stress strains, temperatures, light and the like into electric signals. The application of the magnetic sensor is very wide, and the magnetic sensor has important roles in the fields of national economy, national defense construction, science and technology, medical and health and the like, wherein products such as an angle sensor, an encoder and the like are important components of the magnetic sensing technology. FIG. 1 shows a typical application of a magnetic angle sensor and encoder chip with a magnet placed directly above the chip: the magnet is rotated, and the output of the chip follows the ferromagnetic rotation angle.
FIG. 2 is a block diagram of an exemplary system of magnetic angle sensors and encoders, wherein: the magneto-sensitive unit-X and the magneto-sensitive unit-Y are two mutually orthogonal Wheatstone bridges which are respectively used for detecting the magnetic field intensity in the X direction and the Y direction and converting the magnetic field intensity into voltage signals (Vx/Vy); then amplifying and filtering (Vxp/Vyp) the signals, and carrying out analog-to-digital conversion (Dx/Dy), and sending the signals to a digital signal processing module CORDIC; the CORDIC calculates the magnetic field angle from the value of Dx/Dy. From the physical properties of the magnetosensitive unit, the following expression can be obtained:
wherein alpha is the angle to be measured, and theta is the actually measured angle.
In practical applications, parameters (such as sensitivity, offset, consistency, etc.) of the magnetosensitive unit and the signal processing circuit are affected by manufacturing process fluctuation, application environment variation, aging, etc., and non-ideal effects may be generated. The following are provided:
wherein b x 、b y The DC offset error is the magnitude mismatch error (amplitude mismatch), k is the quadrature error. It can be obtained by simple mathematical derivation: the error e between the angle value θ calculated using the formula (2) and the actual angle value α can be approximately expressed using the formula (4).
It can be seen that dc offset errors produce first harmonic errors, and amplitude mismatch errors and quadrature errors produce second harmonic errors.
In addition, non-idealities of the magnet (including magnetizing non-uniformity, magnetic axis offset, etc.) can also produce harmonic errors, and the order of the harmonic errors is related to the number of poles of the magnet, with the number of poles being greater the higher the order of the harmonic errors.
In view of this, there is an urgent need to design a new harmonic calibration method to overcome at least some of the above-mentioned drawbacks of the existing harmonic calibration methods.
Disclosure of Invention
The invention provides a harmonic calibration system and method, and an error harmonic component coefficient calculation system and method, which can eliminate various harmonic errors and improve detection accuracy.
In order to solve the technical problems, according to one aspect of the present invention, the following technical scheme is adopted:
a harmonic calibration system, the harmonic calibration system comprising:
a differentiator for generating a differential signal;
the input end of the first mixer is connected with the differentiator and is used for mixing the standard sinusoidal signal and the differential signal;
the input end of the second mixer is connected with the differentiator and is used for mixing the standard cosine signal and the differential signal;
the input end of the first integrating unit is connected with the output end of the first mixer, and integrates the signal output by the first mixer;
the input end of the second integrating unit is connected with the output end of the second mixer, and integrates the signal output by the second mixer;
the input end of the sine harmonic coefficient acquisition module is connected with the output end of the first integration unit, and the sine harmonic coefficient is acquired according to the signal output by the first integration unit;
the input end of the cosine harmonic coefficient acquisition module is connected with the output end of the second integral unit, and the cosine harmonic coefficient is acquired according to the signal output by the second integral unit;
and the harmonic calibration module is respectively connected with the sine harmonic coefficient acquisition module and the cosine harmonic coefficient acquisition module, and eliminates error harmonic components from the original angle signal to obtain a calibrated angle signal.
As an embodiment of the present invention, the sinusoidal harmonic coefficient obtaining module includes a first scaling module, configured to scale a signal output by the first integrating unit to obtain a sinusoidal harmonic coefficient;
the cosine harmonic coefficient acquisition module comprises a second scaling module, and is used for scaling the signal output by the second integrating unit to obtain a cosine harmonic coefficient.
As an embodiment of the present invention, the sine harmonic coefficient obtaining module includes a first accumulator, configured to accumulate signals output by the first integrating unit to obtain sine harmonic coefficients; and feeding the output of the differential device back to the input end of the differential device to make a difference with the original signal, so as to obtain a compensated angle signal;
the cosine harmonic coefficient acquisition module comprises a second accumulator, and is used for accumulating signals output by the second integration unit to obtain cosine harmonic coefficients; and feeding the output of the differential device back to the input end of the differential device to make a difference with the original signal, so as to obtain a compensated angle signal.
As an embodiment of the present invention, the harmonic calibration system further includes:
the standard sinusoidal signal generating module is used for generating a standard sinusoidal signal;
the standard cosine signal generating module is used for generating a standard cosine signal.
According to another aspect of the invention, the following technical scheme is adopted: an error harmonic component coefficient computing system, the computing system comprising:
a differentiator for generating a differential signal;
the input end of the first mixer is connected with the differentiator and is used for mixing the standard sinusoidal signal and the differential signal;
the input end of the second mixer is connected with the differentiator and is used for mixing the standard cosine signal and the differential signal;
the input end of the first integrating unit is connected with the output end of the first mixer, and integrates the signal output by the first mixer;
the input end of the second integrating unit is connected with the output end of the second mixer, and integrates the signal output by the second mixer;
the input end of the sine harmonic coefficient acquisition module is connected with the output end of the first integration unit, and the sine harmonic coefficient is acquired according to the signal output by the first integration unit;
and the input end of the cosine harmonic coefficient acquisition module is connected with the output end of the second integral unit, and the cosine harmonic coefficient is acquired according to the signal output by the second integral unit.
According to a further aspect of the invention, the following technical scheme is adopted: a method of harmonic calibration, the method comprising:
differentiating the set angle signals, mixing with a standard sine signal and a standard cosine signal, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients; and eliminating an error harmonic component from the original angle signal to obtain a calibrated angle signal.
As one embodiment of the present invention, when the magnet rotates at a constant speed, the angle signal θ calculated by the CORDIC module contains an error component, and θ (t) is expanded into formula (5) according to the taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen it canConverting equation (6) to the digital domain, as equation (7);
wherein,is the digital domain angular frequency. The embodiment of formula (7) is as follows:
the CORDIC module outputs an angle signal theta to be divided into two paths, one path generates a standard sine signal sin (mtheta) and a standard cosine signal cos (mtheta) through the I-CORDIC module, the other path mixes with the standard sine signal sin (mtheta) and the standard cosine signal cos (mtheta) respectively after passing through the differentiator, delta theta cm and delta theta sm are obtained through respective integration units respectively, and finally current m-order harmonic component coefficients ksm and kcm are obtained through the scaling module;
and feeding back harmonic component coefficients ksm and kcm to a harmonic calibration module, and eliminating m-order error harmonic components from the original angle signal theta to obtain an angle signal after m-order calibration.
As one embodiment of the present invention, when the error contains a plurality of harmonic components, the error harmonic component coefficients are calculated in parallel by adding branches, or the error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so as to achieve the elimination of the error harmonic components of each order.
As an embodiment of the present invention, the method further comprises: the output of the accumulator is fed back to the input end of the differentiator to be differenced with the original signal theta to obtain a compensated angle signal theta_cal (n), so that closed-loop control is realized;
if θ_cal (n) contains an m-order error harmonic component, δθcm and δθsm are not 0 and the process continuesAnd accumulating harmonic component coefficients on the module until the m-order error harmonic component is not contained in the theta_cal (n), and finally realizing the self-adaptive elimination of the m-order error harmonic component.
As an embodiment of the present invention, when the error contains multiple harmonic components, error harmonic component coefficients are calculated in parallel by adding feedback branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so as to achieve elimination of each order of error harmonic components.
As an embodiment of the present invention, the method further comprises: the calibrated angle signal theta_cal is used for replacing the original angle signal theta to generate a standard sine and cosine signal.
According to a further aspect of the invention, the following technical scheme is adopted: a method of error harmonic component coefficient calculation, the method comprising: and differentiating the set angle signals, mixing with the standard sine signals and the standard cosine signals, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients.
The invention has the beneficial effects that: the harmonic calibration system and method and the error harmonic component coefficient calculation system and method provided by the invention can eliminate various harmonic errors and improve the detection accuracy.
According to the error characteristics of the magnetic angle sensor and the encoder, the invention provides a novel harmonic calibration algorithm; the invention provides a method for adaptively calculating and compensating harmonic error components of each order by utilizing a Least Mean Square (LMS) principle; the invention further provides that the calibrated angle signal is used for replacing the original angle signal to generate the standard sine and cosine signal so as to realize higher-precision error harmonic component compensation.
The invention can effectively eliminate various harmonic errors introduced by the magnetic angle sensor and the encoder in the links of production, installation test, application and the like by utilizing a harmonic calibration algorithm, including but not limited to the following causes: parameter fluctuation of the magnetosensitive unit and the signal processing circuit caused by manufacturing process fluctuation, application environment change, device aging and other reasons; non-uniformity in magnetizing of the magnet, misalignment of the magnetic axis due to mounting tolerances, and the like.
The self-adaptive algorithm provided by the invention can simplify the testing complexity of the magnetic angle sensor and the encoder in the actual production, manufacture and application processes. In addition, the standard sine and cosine signal generation mode provided by the invention can greatly improve the compensation precision of the error harmonic component.
Drawings
FIG. 1 is a typical application of a magnetic angle sensor and encoder chip.
FIG. 2 is a block diagram of an exemplary system of magnetic angle sensors and encoders.
FIG. 3 is a schematic diagram illustrating a system for calculating coefficients of error harmonic components according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of an error harmonic component calibration system according to an embodiment of the invention.
FIG. 5 is a schematic diagram of an adaptive harmonic calibration system according to an embodiment of the present invention.
FIG. 6 is a schematic diagram illustrating an error harmonic component calibration system for generating standard sine and cosine signals using calibrated angle signals according to an embodiment of the present invention.
FIG. 7 is a schematic diagram of an adaptive harmonic calibration system for generating standard sine and cosine signals using calibrated angle signals according to an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The description of this section is intended to be illustrative of only a few exemplary embodiments and the invention is not to be limited in scope by the description of the embodiments. It is also within the scope of the description and claims of the invention to interchange some of the technical features of the embodiments with other technical features of the same or similar prior art.
The description of the steps in the various embodiments in the specification is merely for convenience of description, and the implementation of the present application is not limited by the order in which the steps are implemented. "connected" in the specification includes both direct and indirect connections.
The invention provides a harmonic calibration method according to the error characteristics of a magnetic angle sensor and an encoder, which comprises the following steps: when the magnet rotates at a constant speed, the angle signal θ calculated by the CORDIC module (coordinate rotation digital computing module) 8 contains an error component, θ (t) can be expanded into formula (5) according to the taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient. The harmonic component coefficients ksm and kcm of each order can be extracted using equation (6),
if orderEquation (6) can be converted to the digital domain, as equation (7),
wherein,is the digital domain angular frequency.
As can be seen from the formula (7), the calculation of the ksm and kcm parameters requires that the angle signal θ output by the CORDIC module is first differentiated and then mixed with the standard sine and cosine signal, and then integrated, and the process can be implemented by using the system block diagram shown in fig. 3: the angle signal theta output by the CORDIC module 8 is divided into two paths, one path generates standard sine and cosine signals sin (mθ) and cos (mθ) through an I-CORDIC module (anti-coordinate rotation digital computing module) 9, and the other path passes through a differentiator 1 (1-z) -1 ) Mixing with sin (mθ) and cos (mθ), respectively, integrating to obtain δθcm and δθsm, and passing throughThe first scaling module 61 and the second scaling module 71 can obtain the current m-order harmonic component coefficients ksm and kcm. By applying the coefficients ksm and kcm to the harmonic calibration module shown in fig. 4, the m-order error harmonic component can be eliminated from the original angle signal θ, and an m-order calibrated angle signal θ_cal_m can be obtained.
When the error contains various harmonic components, the error harmonic component coefficients can be calculated through adding branches in parallel, and the error harmonic component coefficients can be calculated in series through modifying m-value time division multiplexing, so that the elimination of the error harmonic components of each order can be realized.
Based on this, the invention further proposes a method for adaptively calculating and compensating the harmonic error components of each order by using the Least Mean Square (LMS) principle, and the structure is as shown in fig. 5: scaling module in FIG. 3Replaced by accumulator->And feeds back its output to the differentiator (1-z -1 ) And the input end of the angle signal is differenced with the original signal theta to obtain a compensated angle signal theta_cal (n), thereby realizing closed-loop control. As can be seen from the knowledge about the control theory, as long as the m-order error harmonic component is contained in the theta_cal (n), delta theta cm and delta theta sm are not 0, and the control theory can continue to +.>And accumulating harmonic component coefficients on the module until the m-order error harmonic component is not contained in the theta_cal (n), and finally realizing the self-adaptive elimination of the m-order error harmonic component.
When the error contains various harmonic components, the error harmonic component coefficients can be calculated in parallel by adding a feedback branch, and the error harmonic component coefficients can be calculated in series by modifying m-value time division multiplexing so as to realize elimination of each order of error harmonic components.
The standard sine and cosine signals sin (mθ) and cos (mθ) of the two error harmonic compensation systems are generated by the original angle signal θ, whether the open loop structure shown in fig. 4 or the closed loop structure shown in fig. 5; when the error harmonic component is smaller, the harmonic component of the sine and cosine signal generated by the original angle signal theta is also relatively smaller, and can be approximated to a standard sine and cosine signal, and finally, higher-precision error harmonic component compensation can be realized. However, when the error harmonic component is large, the harmonic component of the sine and cosine signal generated from the original angle signal θ is also relatively large, eventually resulting in low error harmonic component compensation accuracy and possibly even deteriorating a part of the harmonic component.
In order to deal with the situation that the original error harmonic component is larger, the invention further provides an improved structure on the basis of the structures shown in fig. 4 and 5, and as shown in fig. 6 and 7, the calibrated angle signal theta_cal is used for replacing the original angle signal theta to generate a standard sine and cosine signal, so that the error harmonic components contained in sin (mtheta) and cos (mtheta) are greatly reduced, and finally, higher-precision error harmonic component compensation can be realized. The cost of this structure is to introduce an extra feedback branch, and the stability of the system needs to be considered in the use process, and the details refer to the related theory of automatic control, which is not described herein.
FIG. 3 is a schematic diagram illustrating a system for calculating the error harmonic component coefficients according to an embodiment of the present invention; the computing system comprises a differentiator 1, a first mixer 2, a second mixer 3, a first integration unit 4, a second integration unit 5, a sine harmonic coefficient acquisition module 6 and a cosine harmonic coefficient acquisition module 7.
The differentiator 1 is used for generating a differential signal; the input end of the first mixer 2 is connected with the differentiator 1 and is used for mixing a standard sine signal and a differential signal; the input end of the second mixer 3 is connected to the differentiator 1 for mixing the standard cosine signal and the differential signal.
The input end of the first integrating unit 4 is connected with the output end of the first mixer 2, and integrates the signal output by the first mixer 2; the input end of the second integrating unit 5 is connected to the output end of the second mixer 3, and integrates the signal output by the second mixer 3.
The input end of the sine harmonic coefficient acquisition module 6 is connected with the output end of the first integration unit 4, and sine harmonic coefficients are acquired according to signals output by the first integration unit 4; the input end of the cosine harmonic coefficient acquisition module 7 is connected with the output end of the second integration unit 5, and the cosine harmonic coefficient is acquired according to the signal output by the second integration unit 5.
As shown in fig. 3, 5, and 7, in one embodiment, the computing system further includes a delay unit (Z -1 ). As shown in fig. 3, in an embodiment, the CORDIC module 8 is connected to the differentiator 1 through a delay unit.
The invention also discloses a harmonic calibration system (which can be used for the harmonic calibration of an angle sensor, and can be used in other fields which can be considered by a person skilled in the art according to the prior art), and fig. 4 is a schematic diagram of the composition of an error harmonic component calibration system in an embodiment of the invention; the harmonic calibration system comprises an error harmonic component coefficient calculation system and a harmonic calibration module shown in fig. 3. The harmonic calibration module is respectively connected with the sine harmonic coefficient acquisition module 6 and the cosine harmonic coefficient acquisition module 7, and eliminates error harmonic components from the original angle signals to obtain calibrated angle signals.
Referring to fig. 3, in an embodiment of the present invention, the sinusoidal harmonic coefficient obtaining module 6 includes a first scaling module 61 for scaling the signal output by the first integrating unit 4 to obtain a sinusoidal harmonic coefficient. The cosine harmonic coefficient obtaining module 7 includes a second scaling module 71 for scaling the signal output by the second integrating unit 5 to obtain a cosine harmonic coefficient.
FIG. 5 is a schematic diagram of an adaptive harmonic calibration system according to an embodiment of the present invention; in an embodiment of the present invention, the sinusoidal harmonic coefficient obtaining module 6 includes a first accumulator 62, configured to accumulate the signals output by the first integrating unit 4 to obtain sinusoidal harmonic coefficients; and feeds back the output to the input end of the differentiator 1 to be differenced with the original signal, so as to obtain the compensated angle signal. The cosine harmonic coefficient acquisition module 7 includes a second accumulator 72 for accumulating the signals output by the second integrating unit to obtain cosine harmonic coefficients; and feeds back the output to the input end of the differentiator 1 to be differenced with the original signal, so as to obtain the compensated angle signal.
In an embodiment of the invention, the harmonic calibration system further comprises: a standard sine signal generation module and a standard cosine signal generation module; the standard sinusoidal signal generating module is used for generating a standard sinusoidal signal; the standard cosine signal generating module is used for generating a standard cosine signal. As shown in fig. 3 and 5, in one embodiment, the I-CORDIC module 9 is used as a standard sine signal generating module and a standard cosine signal generating module for generating standard sine and cosine signals sin (mθ) and cos (mθ).
The invention discloses a method for calculating an error harmonic component coefficient, which comprises the following steps: and differentiating the set angle signals, mixing with the standard sine signals and the standard cosine signals, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients.
Referring to fig. 3, in an embodiment of the present invention, an angle signal θ output by a CORDIC module is divided into two paths, one path generates a standard sine signal sin (mθ) and a standard cosine signal cos (mθ) through an I-CORDIC module, the other path mixes with the standard sine signal sin (mθ) and the standard cosine signal cos (mθ) respectively after passing through a differentiator, then obtains δθcm and δθsm through respective integrating units respectively, and finally obtains current m-order harmonic component coefficients ksm and kcm through a scaling module.
The invention further discloses a harmonic calibration method, comprising: differentiating the set angle signals, mixing with a standard sine signal and a standard cosine signal, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients; and eliminating an error harmonic component from the original angle signal to obtain a calibrated angle signal.
Referring to fig. 3, in an embodiment of the present invention, a CORDIC output angle signal θ is divided into two paths, one path generates a standard sine signal sin (mθ) and a standard cosine signal cos (mθ) through an I-CORDIC module, the other path mixes with the standard sine signal sin (mθ) and the standard cosine signal cos (mθ) respectively after passing through a differentiator, then obtains δθcm and δθsm through respective integrating units, and finally obtains current m-order harmonic component coefficients ksm and kcm through a scaling module. And feeding back harmonic component coefficients ksm and kcm to a harmonic calibration module, and eliminating m-order error harmonic components from the original angle signal theta to obtain an angle signal after m-order calibration.
In an embodiment of the present invention, when the error includes a plurality of harmonic components, error harmonic component coefficients are calculated in parallel by adding branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so as to achieve each order of error harmonic component cancellation.
When the magnet rotates at a constant speed, the angle signal theta calculated by the CORDIC contains an error component, theta (t) is expanded into a formula (5) according to the taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen equation (6) can be converted to the digital domain, as equation (7);
wherein,is the digital domain angular frequency.
In an embodiment of the invention, the method further comprises: and feeding back the output of the accumulator to the input end of the differentiator to make a difference with the original signal theta to obtain a compensated angle signal theta_cal (n), thereby realizing closed-loop control.
If θ_cal (n) contains an m-order error harmonic component, δθcm and δθsm are not 0 and the process continuesAnd accumulating harmonic component coefficients on the module until the m-order error harmonic component is not contained in the theta_cal (n), and finally realizing the self-adaptive elimination of the m-order error harmonic component.
In an embodiment of the present invention, when the error includes multiple harmonic components, the error harmonic component coefficients are calculated in parallel by adding feedback branches, or the error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so as to achieve the elimination of the error harmonic components of each order.
In an embodiment, the method further comprises: the calibrated angle signal theta_cal is used for replacing the original angle signal theta to generate a standard sine and cosine signal.
In summary, the harmonic calibration system and method, and the error harmonic component coefficient calculation system and method provided by the invention can eliminate various harmonic errors and improve the detection accuracy.
It should be noted that the present application may be implemented in software and/or a combination of software and hardware; for example, an Application Specific Integrated Circuit (ASIC), a general purpose computer, or any other similar hardware device may be employed. In some embodiments, the software programs of the present application may be executed by a processor to implement the above steps or functions. Likewise, the software programs of the present application (including related data structures) may be stored in a computer-readable recording medium; such as RAM memory, magnetic or optical drives or diskettes, and the like. In addition, some steps or functions of the present application may be implemented in hardware; for example, as circuitry that cooperates with the processor to perform various steps or functions.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The description and applications of the present invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. Effects or advantages referred to in the embodiments may not be embodied in the embodiments due to interference of various factors, and description of the effects or advantages is not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (9)
1. A harmonic calibration system, the harmonic calibration system comprising:
a differentiator for generating a differential signal;
the input end of the first mixer is connected with the differentiator and is used for mixing the standard sinusoidal signal and the differential signal;
the input end of the second mixer is connected with the differentiator and is used for mixing the standard cosine signal and the differential signal;
the input end of the first integrating unit is connected with the output end of the first mixer, and integrates the signal output by the first mixer;
the input end of the second integrating unit is connected with the output end of the second mixer, and integrates the signal output by the second mixer;
the input end of the sine harmonic coefficient acquisition module is connected with the output end of the first integration unit, and the sine harmonic coefficient is acquired according to the signal output by the first integration unit;
the input end of the cosine harmonic coefficient acquisition module is connected with the output end of the second integral unit, and the cosine harmonic coefficient is acquired according to the signal output by the second integral unit;
the harmonic calibration module is respectively connected with the sine harmonic coefficient acquisition module and the cosine harmonic coefficient acquisition module, and eliminates error harmonic components from the original angle signals to obtain calibrated angle signals;
the coordinate rotation digital calculation module is used for calculating an angle signal theta containing an error component when the magnet rotates at a constant speed, expanding the theta (t) into a formula (5) according to a Taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen convert equation (6) to the digital domain, as equation (7);
wherein,is the digital domain angular frequency; the embodiment of formula (7) is as follows:
the coordinate rotation digital computing module outputs an angle signal theta to be divided into two paths, one path generates a standard sine signal sin (mtheta) and a standard cosine signal cos (mtheta) through the I-CORDIC module, the other path mixes with the standard sine signal sin (mtheta) and the standard cosine signal cos (mtheta) respectively after passing through the differentiator, delta theta cm and delta theta sm are obtained through respective integrating units respectively, and finally current m-order harmonic component coefficients ksm and kcm are obtained through the scaling module;
the harmonic component coefficients ksm and kcm are fed back to a harmonic calibration module, and m-order error harmonic components are eliminated from an original angle signal theta, so that an angle signal after m-order calibration is obtained;
when the error contains various harmonic components, error harmonic component coefficients are calculated in parallel by adding branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so that the elimination of each order of error harmonic components is realized.
2. The harmonic calibration system of claim 1, wherein:
the sine harmonic coefficient acquisition module comprises a first scaling module, a second scaling module and a third scaling module, wherein the first scaling module is used for scaling the signal output by the first integration unit to obtain a sine harmonic coefficient;
the cosine harmonic coefficient acquisition module comprises a second scaling module, and is used for scaling the signal output by the second integrating unit to obtain a cosine harmonic coefficient.
3. The harmonic calibration system of claim 1, wherein:
the sine harmonic coefficient acquisition module comprises a first accumulator, a second accumulator and a third accumulator, wherein the first accumulator is used for accumulating signals output by the first integration unit to obtain sine harmonic coefficients; the output of the accumulator is fed back to the input end of the differentiator to be differenced with the original signal, and a compensated angle signal is obtained;
the cosine harmonic coefficient acquisition module comprises a second accumulator, and is used for accumulating signals output by the second integration unit to obtain cosine harmonic coefficients; and feeding back the output of the accumulator to the input end of the differentiator to make a difference with the original signal, so as to obtain a compensated angle signal.
4. The harmonic calibration system of claim 1, wherein:
the harmonic calibration system further comprises:
the standard sinusoidal signal generating module is used for generating a standard sinusoidal signal;
the standard cosine signal generating module is used for generating a standard cosine signal.
5. An error harmonic component coefficient computing system, the computing system comprising:
a differentiator for generating a differential signal;
the input end of the first mixer is connected with the differentiator and is used for mixing the standard sinusoidal signal and the differential signal;
the input end of the second mixer is connected with the differentiator and is used for mixing the standard cosine signal and the differential signal;
the input end of the first integrating unit is connected with the output end of the first mixer, and integrates the signal output by the first mixer;
the input end of the second integrating unit is connected with the output end of the second mixer, and integrates the signal output by the second mixer;
the input end of the sine harmonic coefficient acquisition module is connected with the output end of the first integration unit, and the sine harmonic coefficient is acquired according to the signal output by the first integration unit;
the input end of the cosine harmonic coefficient acquisition module is connected with the output end of the second integral unit, and the cosine harmonic coefficient is acquired according to the signal output by the second integral unit;
the coordinate rotation digital calculation module is used for calculating an angle signal theta containing an error component when the magnet rotates at a constant speed, expanding the theta (t) into a formula (5) according to a Taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen equation (6) can be converted to the digital domain, as equation (7);
wherein,is the digital domain angular frequency; the embodiment of formula (7) is as follows:
the coordinate rotation digital computing module outputs an angle signal theta to be divided into two paths, one path generates a standard sine signal sin (mtheta) and a standard cosine signal cos (mtheta) through the I-CORDIC module, the other path mixes with the standard sine signal sin (mtheta) and the standard cosine signal cos (mtheta) respectively after passing through the differentiator, delta theta cm and delta theta sm are obtained through respective integrating units respectively, and finally current m-order harmonic component coefficients ksm and kcm are obtained through the scaling module;
the harmonic component coefficients ksm and kcm are fed back to a harmonic calibration module, and m-order error harmonic components are eliminated from an original angle signal theta, so that an angle signal after m-order calibration is obtained;
when the error contains various harmonic components, error harmonic component coefficients are calculated in parallel by adding branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so that the elimination of each order of error harmonic components is realized.
6. A method of harmonic calibration, the method comprising:
differentiating the set angle signals, mixing with a standard sine signal and a standard cosine signal, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients; eliminating error harmonic components from the original angle signals to obtain calibrated angle signals;
when the magnet rotates at a constant speed, the angle signal theta calculated by the CORDIC module contains an error component, theta (t) is unfolded into a formula (5) according to the taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen equation (6) can be converted to the digital domain, as equation (7);
wherein,is the digital domain angular frequency; the embodiment of formula (7) is as follows:
the CORDIC module outputs an angle signal theta to be divided into two paths, one path generates a standard sine signal sin (mtheta) and a standard cosine signal cos (mtheta) through the I-CORDIC module, the other path mixes with the standard sine signal sin (mtheta) and the standard cosine signal cos (mtheta) respectively after passing through the differentiator, delta theta cm and delta theta sm are obtained through respective integration units respectively, and finally current m-order harmonic component coefficients ksm and kcm are obtained through the scaling module;
the harmonic component coefficients ksm and kcm are fed back to a harmonic calibration module, and m-order error harmonic components are eliminated from an original angle signal theta, so that an angle signal after m-order calibration is obtained;
when the error contains various harmonic components, error harmonic component coefficients are calculated in parallel by adding branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so that the elimination of each order of error harmonic components is realized.
7. The method of harmonic calibration according to claim 6, wherein:
the method further comprises: the output of the accumulator is fed back to the input end of the differentiator to be differenced with the original signal theta to obtain a compensated angle signal theta_cal (n), so that closed-loop control is realized;
as long as the m-order error harmonic component is contained in θcal (n), δθcm and δθsm are not 0 and continue to the accumulator moduleAccumulating harmonic component coefficients until the theta_cal (n) does not contain m-order error harmonic components, and finally realizing the self-adaptive elimination of the m-order error harmonic components;
when the error contains various harmonic components, error harmonic component coefficients are calculated in parallel by adding a feedback branch, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so that the elimination of each order of error harmonic components is realized.
8. The method of harmonic calibration according to claim 6, wherein:
the method further comprises: the calibrated angle signal theta_cal is used for replacing the original angle signal theta to generate a standard sine and cosine signal.
9. A method for calculating an error harmonic component coefficient, the method comprising:
differentiating the set angle signals, mixing with a standard sine signal and a standard cosine signal, and integrating to obtain sine harmonic coefficients and cosine harmonic coefficients;
when the magnet rotates at a constant speed, the angle signal theta calculated by the CORDIC module contains an error component, theta (t) is unfolded into a formula (5) according to the taylor formula,
where w is the angular velocity of the magnet rotation, m is the harmonic order, ksm is the sine harmonic coefficient, and kcm is the cosine harmonic coefficient; extracting harmonic component coefficients ksm and kcm of each order by using a formula (6);
if orderThen equation (6) can be converted to the digital domain, as equation (7);
wherein,is the digital domain angular frequency; the embodiment of formula (7) is as follows:
the coordinate rotation digital computing module outputs an angle signal theta to be divided into two paths, one path generates a standard sine signal sin (mtheta) and a standard cosine signal cos (mtheta) through the I-CORDIC module, the other path mixes with the standard sine signal sin (mtheta) and the standard cosine signal cos (mtheta) respectively after passing through the differentiator, delta theta cm and delta theta sm are obtained through respective integrating units respectively, and finally current m-order harmonic component coefficients ksm and kcm are obtained through the scaling module;
the harmonic component coefficients ksm and kcm are fed back to a harmonic calibration module, and m-order error harmonic components are eliminated from an original angle signal theta, so that an angle signal after m-order calibration is obtained;
when the error contains various harmonic components, error harmonic component coefficients are calculated in parallel by adding branches, or error harmonic component coefficients are calculated in series by modifying m-value time division multiplexing, so that the elimination of each order of error harmonic components is realized.
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