CN105841867A - Measuring method for tooth groove torque of permanent magnet motor - Google Patents
Measuring method for tooth groove torque of permanent magnet motor Download PDFInfo
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- CN105841867A CN105841867A CN201610346067.XA CN201610346067A CN105841867A CN 105841867 A CN105841867 A CN 105841867A CN 201610346067 A CN201610346067 A CN 201610346067A CN 105841867 A CN105841867 A CN 105841867A
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0061—Force sensors associated with industrial machines or actuators
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Abstract
The invention discloses a wavelet-signal-analysis-based measuring method for tooth groove torque of a permanent magnet motor. The method comprises: a torque sensor is used for detecting a measured permanent magnet motor; a signal pre-treatment module carries out conditioning on a sensing signal; according to a preset sampling frequency fs and a sampling point number N, a signal acquisition module extracts a torque signal output frequency f of the sensing signal after conditioning, wherein the f meets a formula: f=fs/N, and a torque signal of the measured permanent magnet motor is calculated; a feature extraction module carries out multi-resolution decomposition on the torque signal to obtain a wavelet coefficient of the torque signal and corrects the wavelet coefficient; and wavelet reconstruction is carried out by using the corrected wavelet coefficient, thereby obtaining a tooth groove torque of the measured permanent magnet motor. According to the invention, the method is easy to implement; the measurement difficulty is low; the measurement precision is high, and the cost is low.
Description
Technical field
The present invention relates to the optimum design and control technical field of magneto, particularly relate to a kind of magneto
The measuring method of cogging torque.
Background technology
Along with improving constantly of permanent magnetic material performance, magneto is increasingly widely used in high-performance speed
With position Mechanical & electrical Transmission Control system, such as fields such as Digit Control Machine Tool, robot, electronic manufacture, elevators.So
And, in magneto, permanent magnet and grooved armature iron core interact, and inevitably produce teeth groove
Torque, its result causes torque ripple, causes vibration and noise, have impact on the control accuracy of system.
Cogging torque is the distinctive problem of magneto, is the physical quantity relevant to position, complete at motor manufacturing
Will not change after one-tenth.Cogging torque is to must take into and solve in high-performance permanent magnet design of electrical motor and manufacture
Critical problem.In high performance machine electric servo system, the magneto of bigger cogging torque can not meet
The requirement of high performance control.Such as, the Permanent Magnet and Electric in the system such as high speed and super precision Digit Control Machine Tool, industrial robot
Machine designs, and its primary demand is exactly Low gullet torque, because too high cogging torque can affect positioning precision.
The cogging torque of magneto is measured, current domestic two kinds of methods of usual employing: is lever mensuration.This
Kind of method is simple, directly perceived, be easily achieved, but precision is difficult to ensure that, can only react the general letter of cogging torque
Breath, cannot use under certainty of measurement requires high occasion.Two is the static measurement using stepper motor,
Namely it is conventional to dragging method.Its concrete metering system is: use the stepper motor that a torque pulsation is the least
With the reductor of a high speed reducing ratio, by connecting reductor, motor speed to be measured is reduced, turn with rotating speed
The torque pulsation in rotating shaft measured by square instrument, is cogging torque.The method requires that torque sensor precision is high,
Measuring method is complicated, and instrument cost is high, and test function is single.
Summary of the invention
The technical problem to be solved is to provide a kind of cogging torque of permanent magnet motor being easily achieved
Measuring method, the cogging torque reducing magneto is measured the cost of system, is improved its certainty of measurement.
For solving above technical problem, the embodiment of the present invention provides a kind of cogging torque of permanent magnet motor measuring method,
Including:
Step 101: tested magneto is detected by torque sensor, exports described torque sensor
Transducing signal sends to signal pre-processing module;
Step 102: described transducing signal is nursed one's health by described signal pre-processing module;
Step 103: signal acquisition module is according to sample frequency f presetsWith sampling number N, extract conditioning
After transducing signal in actual measurement torque output frequency value f=fs/N;
Step 104: described signal acquisition module is according to conversion formula M=A × (f-f0)/(fp-f0), meter
Calculate the dtc signal M of described tested magneto;Wherein, A is torque full scale, and f is defeated for actual measurement torque
Go out frequency values, f0For torque offset output frequency values, fpFor forward Full-span output frequency values;
Step 105: the described dtc signal collected is transmitted to feature extraction mould by described signal acquisition module
Block;Described dtc signal includes cogging torque signal;
Step 106: described characteristic extracting module utilizes wavelet transform to differentiate described dtc signal more
Rate is decomposed, it is thus achieved that the wavelet coefficient of described dtc signal;
Step 107: described characteristic extracting module is according to the pulsation of the cogging torque signal of described tested magneto
Frequency, is modified described wavelet coefficient;
Step 108: described characteristic extracting module uses revised wavelet coefficient to carry out wavelet reconstruction, it is thus achieved that institute
State the cogging torque signal of tested magneto.
Preferably, described signal pre-processing module includes: the voltage follower, the signal that are sequentially connected with amplify electricity
Road, wave filter and shaping circuit;Described step 102 specifically includes:
Step 201: the magnitude of voltage of described transducing signal is adjusted by described voltage follower, so that described electricity
The output voltage of pressure follower matches with input voltage;
Step 202: the transducing signal that described voltage follower is exported by described signal amplification circuit is amplified;
Step 203: the interference signal in the transducing signal after amplification process is filtered by described wave filter;
Step 204: filtered transducing signal is shaped as rectangular pulse signal by described shaping circuit, and provides
To data collecting card.
Preferred embodiment central in one, described wave filter is the second order active using hardware circuit to realize
Low pass filter.
In the middle of another preferred embodiment, described wave filter uses the mode of software filtering to sensing letter
Number it is filtered.
Preferably, described step 106 specifically includes:
Step 601: after described characteristic extracting module treats that the sample rate of described dtc signal meets sampling thheorem,
The total frequency band occupied by the signal collected is defined as SPACE V0, described total frequency band is 0~fs/2;Through a fraction
Xie Hou, by V0It is divided into low frequency subspace V1With high frequency subspace W1;, described V1Frequency band be 0~fs/ 4,
Described W1Frequency band is fs/ 4~fs/2;
Step 602: after two grades are decomposed, by described V1It is decomposed into low frequency subspace V2With high frequency subspace
W2, described V2Frequency band be 0~fs/ 8, described W2Frequency band be fs/ 8~fs/4;And so on, by frequency
Uniformly subdivision is: V0=V1⊕W1, V1=V2⊕W2..., Vj-1=Vj⊕Wj, therefore:
V0=W1⊕W2⊕W3......Wj⊕Vj
Wherein, each WjIt is reflection Vj-1The high frequency subspace of spacing wave details, VjIt is reflection Vj-1Spacing wave
The low frequency subspace of details, WjFor VjAt Vj-1The orthogonal complement space;
Step 603: by multiresolution analysis and orthogonal space resolution theory,Wherein J is
Arbitrarily yardstick, by signal x (t) ∈ L2(R) at space L2(R) upper launch, obtain following expression:
Wherein, Double-scaling equation is:
Ifdj+1,n=< fj,ψj+1,n>, and then decompose and obtain wavelet coefficient and be:
Wherein, k=0,1,2 ... n-1, represent translation position;The j frequency range to induction signal;cj+1,k, dj+1,kFor
Described wavelet coefficient;H (k) is low pass filter sampling response;G (k) is high-pass filter sampling response;
For scaling function;ψj,kT () is wavelet function.
Preferably, described step 107 comprises the following steps:
Step 701: according to rotating speed v and teeth groove quantity Z of described tested magneto, calculate described tested
Cogging torque ripple frequency f of magnetoc=v × Z/60;
Step 702: according to described dtc signal output frequency f and described cogging torque ripple frequency fc, select
Small echo;And determine number of plies n of wavelet decomposition, wherein n > 0;
Step 703: described dtc signal is carried out 1 wavelet transform arriving n-layer, decomposes and obtain each layer
Wavelet coefficient;
Step 704: retain and described cogging torque ripple frequency fcThe component of corresponding wavelet coefficient, and will
The component zero setting of the wavelet coefficient that remaining frequency range is corresponding, it is thus achieved that revised wavelet coefficient.
Preferably, described small echo is the western small echo of many shellfishes.
Preferably, described step 108 comprises the following steps:
Step 801: utilize the multi-resolution characteristics of small echo, searches the frequency corresponding to cogging torque ripple frequency section
Segment signal;
Step 802: order remaining frequency band signals in addition to the frequency band signals of described correspondence is zero, and process obtains new
Wavelet coefficient;
Step 803: utilize described wavelet coefficient that signal is reconstructed by below equation:
Wherein, cj,kFor cogging torque signal, the signal that reconstruct obtains is cogging torque signal.
The technical scheme that the embodiment of the present invention provides, it provides the benefit that can be to general conventional torque sensor
Transducing signal process, utilize signal acquisition module and data collecting card to extract turning of tested magneto
Square signal, and according to the multi-resolution characteristics of wavelet decomposition, use characteristic extracting module and Industry Control to calculate
DAS in machine carries out wavelet decomposition to dtc signal, and extraction turns with the teeth groove in dtc signal
The wavelet coefficient that square ripple frequency matches carries out wavelet reconstruction, and the final teeth groove obtaining tested magneto turns
Square signal, certainty of measurement is high and is easily achieved, and dtc signal and the industry that can be exported by data collecting card are controlled
The cogging torque signal of computer export processed exports in display and shows, measures more directly perceived and can be real
Time reflected measurement signal parameter situation.
Accompanying drawing explanation
Fig. 1 is that an embodiment flow process of a kind of cogging torque of permanent magnet motor measuring method that the present invention provides is shown
It is intended to;
Fig. 2 is that a kind of of step S102 shown in Fig. 1 can the schematic flow sheet of implementation;
Fig. 3 is that a kind of of step S106 shown in Fig. 1 can the schematic flow sheet of implementation;
Fig. 4 is that a kind of of step S107 shown in Fig. 1 can the schematic flow sheet of implementation;
Fig. 5 is the system test platform structural representation that the present invention provides;
Fig. 6 is a kind of hardware circuit connection figure of signal pre-processing module;
Fig. 7 is motor cogging torque oscillogram.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clearly
Chu, it is fully described by.
See Fig. 1, be an embodiment of the measuring method of a kind of cogging torque of permanent magnet motor that the present invention provides
Schematic flow sheet.
In the present embodiment, by utilize torque sensor, signal pre-processing module, signal acquisition module with
The measurement apparatus of characteristic extracting module, industrial control computer composition, described cogging torque of permanent magnet motor
Measuring method, comprises the following steps S101~step S108:
Step S101: torque sensor detects the torque of tested magneto, is exported by described torque sensor
Transducing signal send to signal pre-processing module.
Step S102: described transducing signal is nursed one's health by described signal pre-processing module.Specifically, its letter
Number conditioning process includes that signal is followed, signal amplifies, signal filtering and signal shaping, its pretreatment or conditioning
Purpose be so that the signal of signal pre-processing module output meets the input signal of next stage processing module
Requirement.
In a kind of attainable mode, signal pre-processing module is made up of hardware circuit.
Referring to Fig. 2, it is that a kind of of step S102 shown in Fig. 1 can the schematic flow sheet of implementation.
Voltage follower that shown signal pre-processing module includes being sequentially connected with, signal amplification circuit, filtering
Device and shaping circuit.
The most described step S102, specifically includes step S201~step S204:
Step S201: the magnitude of voltage of described transducing signal is adjusted by described voltage follower, so that described
The output voltage of voltage follower matches with input voltage.Voltage follower is so that output voltage and input
The circuit that voltage is identical, is characterized in that input impedance is high, output impedance is low, thus voltage follower can conduct
The buffer stage of front stage circuits and late-class circuit and isolation level, thus improve the load capacity of circuit.
Step S202: the transducing signal that described voltage follower is exported by described signal amplification circuit is carried out rationally
Amplify.In the present embodiment, the purpose being amplified transducing signal is to adopt for the ease of late-class circuit signal
The process of collection module, to obtain the highest precision.When being embodied as, to biography near signal source amplitude
Sense signal is amplified, and the destruction of noise will reduce.Preferably, the amplitude that transducing signal amplifies is with letter
The maximum input range of number acquisition module is as the criterion.
Step S203: the interference signal in the transducing signal after amplification process is filtered by described wave filter.
When being embodied as, there is the High-frequency Interference of the electrical equipments such as motor due to measure field, when measured signal is the most weak,
Will cover by disturbed signal (noise etc.), cause the data collected to there is error.According to torque sensing
Device output signal characteristics, can design hardware circuit and realize second order active low pass filter, filter in transducing signal
Unwanted composition or noise.
Alternatively, in the present embodiment, it is possible to use the mode of software filtering, the sensing letter that will collect
Number utilize LabVIEW (Laboratory Virtual Instrument Engineering Workbench) software,
I.e. laboratory virtual instrument Engineering Task platform, transducing signal is filtered by filtration module therein.
Step S204: filtered transducing signal is shaped as rectangular pulse signal by described shaping circuit.Specifically
During enforcement, the transducing signal after torque sensor and filter process is often sawtooth waveforms or off-gauge side
Ripple, after the transducing signal of this waveform is delivered to signal acquisition module, the dtc signal output frequency collected
The data such as rate will form error.Therefore, before transducing signal is carried out dtc signal collection, need to set
Meter shaping circuit carries out shaping to transducing signal.
Step S103: signal acquisition module is according to sample frequency f presetsWith sampling number N, extract tune
Actual measurement torque output frequency value f in transducing signal after reason, wherein f=fs/N.Specifically, signals collecting
Module is realized by data collecting card, it is preferable that described data collecting card chooses NI (National
Instruments) i.e. the PCI-6251 multifunctional data acquisition card of National Instruments realizes.
Specifically, when actual measurement torque output frequency value f is extracted, according to default sample frequency fsWith
Sampling number N, i.e. can obtain the sampling time T=N/f to dtc signals, i.e. gather in time interval T
Obtain a torque value, therefore, the output frequency f=1/T of dtc signal.
In the present embodiment, it is contemplated that follow-up time dtc signal is analyzed, count if sample frequency can not be sampled
Divide exactly, it will cause energy leakage, amplitude distortion.Therefore, sampling number and sample frequency ratio are the most pre-
It is set to integer.Such as, during measuring, when sample frequency f of data collecting cardsFor 1.25MHz (megahertz
Time hereby), can set sampling number as 1250 points, being calculated the sampling period is 1ms (millisecond).The most every 1ms
Transmitting a torque value, it is 1000Hz (hertz) that correspondence obtains the output frequency of torque value.Magneto rotating speed
It is adjusted to 10 revs/min.Then the motor required time that turns around is 6 seconds.The torque value that this period collects
Number is 6000.When being embodied as, can be by the Wave data of dtc signal that collects with electrical form
Form preserves the appointment position to host hard drive.
When being embodied as, PCI-6251 multifunctional data acquisition card both can also may be used in the way of using simulation input
In the way of using counter, dtc signal is acquired.When using the mode of simulation input, by torque
The pulse signal of sensor output collects computer by analog channel;By arranging hits and sampling frequency
Rate, comprises several pulse periods in making the sampling time, will by data collecting card analog signal input channel
After pulse signal completely gathers into, utilize the extraction sub-VI of single-frequency information inside LabVIEW to obtain and turn
The output frequency of square signal.When the mode using counter measures, setting measurement frequency range is
Big value and minimum of a value, utilize survey engineering function to carry out frequency calculating, and multiple frequency values are measured in circulation every time,
And using the mean value of multiple frequencies that records as collecting desired signal.
Step S104: described signal acquisition module is according to conversion formula M=A × (f-f0)/(fp-f0),
Calculate the dtc signal M of described tested magneto.Wherein, A is torque full scale, f0For torque zero point
Output frequency value, fpFor forward Full-span output frequency values.In the present embodiment, described torque letter M > 0
Time, for forward torque output valve;During dtc signal M < 0, for opposing torque output valve.
Step S105: the described dtc signal collected is sent to feature extraction by described signal acquisition module
Module;Described dtc signal includes cogging torque signal.
Step S106: described characteristic extracting module utilizes wavelet transform that described dtc signal is carried out many points
Resolution is decomposed, it is thus achieved that the wavelet coefficient of described dtc signal.When being embodied as, can be by LabVIEW
Calling MATLAB (Matrix Laboratory) software work platform, is mixed by programming realization wavelet transformation
The algorithm of characteristic signal, carries out wavelet decomposition to dtc signal, it is thus achieved that the wavelet coefficient of dtc signal.
MATLAB is a kind of height for algorithm development, data visualization, data analysis and numerical computations
Level technology computational language and interactive environment.
Referring to Fig. 3, it is that dtc signal is differentiated by the wavelet transform that utilizes that the embodiment of the present invention provides more
Rate analyze a kind of can the flow chart of steps of implementation.
When being embodied as, when utilizing wavelet transform that dtc signal is carried out multiresolution analysis, it is concrete
Decomposable process is:
Step S601: after described characteristic extracting module treats that described dtc signal sample rate meets sampling thheorem,
The total frequency band occupied by the signal collected is (if frequency band is 0~fs/ 2) it is defined as SPACE V0, after level of decomposition
V0It is divided into two sub spaces: low frequency subspace V1(frequency band is 0~fs/ 4) and high frequency subspace W1(frequently
Band is fs/ 4~fs/2)。
Step S602: V after two grades are decomposed1It is broken down into again the V of low frequency2(frequency band is 0~fs/ 8) and high
Frequently subspace W2(frequency band is fs/ 8~fs/ 4), and so on.The subdivision of this frequency subspace is as follows:
V0=V1⊕W1, V1=V2⊕W2..., Vj-1=Vj⊕Wj, therefore:
V0=W1⊕W2⊕W3......Wj⊕Vj (1)
Step S603: by multiresolution analysis and orthogonal space resolution theory,Wherein J appoints
Meaning yardstick, by signal x (t) ∈ L2(R) at space L2(R) upper launch, obtain following expression:
Wherein, Double-scaling equation is:
Ifdj+1,n=< fj,ψj+1,n> and then decompose the wavelet coefficient obtained
For:
Wherein, k=0,1,2 ... n-1, represent translation position, only need in limited range value;J is to induction signal
Frequency range;cj+1,k, dj+1,kFor described wavelet coefficient;H (k) is low pass filter sampling response;G (k) is
High-pass filter sampling response;For scaling function;ψj,kT () is wavelet function.
The multiresolution analysis of wavelet transform, the mixed signal formed by various different frequencies is (such as torque
Signal) it is decomposed into the signal of different frequency range, signal is had by frequency band disposal ability.
Step S107: described characteristic extracting module according to the cogging torque signal of described tested magneto
Ripple frequency, is modified described wavelet coefficient.When being embodied as, by equation (5) and equation (6)
Calculating after, obtain dtc signal wavelet coefficient;Pulsation further according to the cogging torque signal in dtc signal
Frequency, extracts the wavelet coefficient matched in the wavelet coefficient of dtc signal with cogging torque signal ripple frequency
Component, and other wavelet coefficient component zero setting, to revise wavelet coefficient.
Referring to Fig. 4, it is that a kind of of step S107 shown in Fig. 1 can the schematic flow sheet of implementation.
Specifically, described step S107 comprises the following steps S701~step S704:
Step S701: according to rotating speed v and teeth groove quantity Z of described tested magneto, calculate described quilt
Survey cogging torque ripple frequency f of magnetoc=v*Z/60.
Step S702: according to described dtc signal output frequency f and described cogging torque ripple frequency fc, select
Small echo;And determine number of plies n of wavelet decomposition, wherein n > 0.
In this embodiment, it is preferred that, described small echo is the western small echo of many shellfishes (Daubechies Wavelet).Many
The western small echo of shellfish is also referred to as DB small echo, and it is to have the small echo that the compactly support of high vanishing moment is orthogonal, in the pressure of signal
Contracting, denoising and Singularity Detection aspect play an important role.
Specifically, in cogging torque ripple frequency fcAfter acquisition, number of plies n of wavelet decomposition small echo is carried out
Can be determined after choosing.One signal length is that the signal of m at most can be analyzed to n=log2M layer, often
One layer all has corresponding frequency range.When being embodied as, each band limits can be obtained by calculating, further according to
Cogging torque ripple frequency finds out its place frequency range, so that it is determined that required number of plies n decomposed of wavelet transformation.
Step S703: described dtc signal is carried out 1 wavelet transform arriving n-layer, decomposes and obtain each layer
Wavelet coefficient.
Step S704: retain and described cogging torque ripple frequency fcThe component of corresponding wavelet coefficient, and
By the component zero setting of wavelet coefficient corresponding for remaining frequency range, it is thus achieved that revised wavelet coefficient.
Further, the measuring method of described cogging torque of permanent magnet motor also includes step S108: described feature
Extraction module uses revised wavelet coefficient to carry out wavelet reconstruction, it is thus achieved that the teeth groove of described tested magneto
Dtc signal.
In a kind of attainable mode, described step S108 specifically includes following steps S801~S803:
Step S801: utilize the multi-resolution characteristics of small echo, finds corresponding to cogging torque ripple frequency section
Frequency band signals.
Step S802: order remaining frequency band signals in addition to the frequency band signals of described correspondence is zero, processes and obtains newly
Wavelet coefficient, the signal that obtains of reconstruct is cogging torque signal.
Step S803: utilize described wavelet coefficient that signal is reconstructed by below equation:
Wavelet reconstruction process is the inverse operation of decomposable process, and the signal that reconstruct obtains is cogging torque signal.
As it is shown in figure 5, be the validity of the magnetic groove torque measuring method that checking the present embodiment proposes further, this
Embodiment constructs the permagnetic synchronous motor system test platform with LabVIEW as upper computer software, Qi Zhongzhu
Partly to have: magnetic powder brake, JN338 digital-type intelligent torque rotary speed sensor, NI PCI-6251 data
Capture card, SCB-68 terminal box, Guangzhou Numerical Control Equipment Co., Ltd GSK SJT series magneto with
And supporting DAH01 series of servo driver, wherein the parameter of JN338 torque rotary speed sensor is: torque
Range 30N.m, the number of teeth 60 tooth, the degree of accuracy 0.5 grade, the linearity≤0.5%F S;The Permanent Magnet and Electric of measurand
Machine parameter is: rated power 1.5kW, rated speed 2500r/min, nominal torque 6N.m, teeth groove number 60.
After the software and hardware part of experiment porch designs, carry out magneto magnetic groove torque measurement experiment.Profit
With JN338 torque sensor, tested magneto is detected, and utilize Signal Pretreatment mould shown in Fig. 6
Surveyed transducing signal is nursed one's health by block.According to default sample frequency fsWith sampling number N, extract conditioning
After the dtc signal output frequency f=f of transducing signals/ N, and calculate the torque letter of described tested magneto
Number.According to formula, dtc signal is carried out Multiresolution Decomposition, calculates the wavelet coefficient of surveyed dtc signal,
And described wavelet coefficient is modified, then revised wavelet coefficient is carried out wavelet reconstruction, it is thus achieved that institute
State the cogging torque signal of tested magneto.
First passing through servo-driver setting and making motor speed perseverance is 10r/min, soft at LabVIEW host computer
The sample frequency of PCI-6251 data collecting card is set in part 600KHz, and gathering counts is set to 600, according to
Formula f=fs/ N, calculating actual measurement torque output frequency is 1000Hz, through overfrequency and torque reduction formula
M=A × (f-f0)/(fp-f0) calculate the dtc signal of described tested magneto.
Then carry out utilizing wavelet transform that described torque is believed according to surveyed dtc signal according to step S106
Number carry out Multiresolution Decomposition and obtain the wavelet coefficient of dtc signal, and by step S107 to obtained wavelet systems
Number is modified, and is reconstructed wavelet coefficient after revising finally by step S108, obtains cogging torque letter
Number, waveform is as shown in Figure 7.
The measuring method of a kind of cogging torque of permanent magnet motor that the embodiment of the present invention provides, can be to general precision
The transducing signal of torque sensor processes, it is not necessary to expensive high accuracy torque sensor of arranging in pairs or groups makes
With, utilize signal acquisition module or data collecting card to extract the faint dtc signal in transducing signal, and according to
The multi-resolution characteristics of wavelet decomposition, carries out wavelet decomposition through MATLAB platform to dtc signal, and extracts
The wavelet coefficient matched with the cogging torque ripple frequency in dtc signal carries out wavelet reconstruction, finally obtains
The cogging torque signal of tested magneto, certainty of measurement is high and is easily achieved.
The above is the preferred embodiment of the present invention, it is noted that for the common skill of the art
For art personnel, under the premise without departing from the principles of the invention, it is also possible to make some improvements and modifications, this
A little improvements and modifications are also considered as protection scope of the present invention.
Claims (8)
1. the measuring method of a cogging torque of permanent magnet motor, it is characterised in that comprise the following steps:
Step 101: tested magneto is detected by torque sensor, exports described torque sensor
Transducing signal sends to signal pre-processing module;
Step 102: described transducing signal is nursed one's health by described signal pre-processing module;
Step 103: signal acquisition module is according to sample frequency f presetsWith sampling number N, extract conditioning
After transducing signal in actual measurement torque output frequency value f=fs/N;
Step 104: described signal acquisition module is according to conversion formula M=A × (f-f0)/(fp-f0), meter
Calculate the dtc signal M of described tested magneto;Wherein, A is torque full scale, and f is defeated for actual measurement torque
Go out frequency values, f0For torque offset output frequency values, fpFor forward Full-span output frequency values;
Step 105: the described dtc signal collected is transmitted to feature extraction mould by described signal acquisition module
Block;Described dtc signal includes cogging torque signal;
Step 106: described characteristic extracting module utilizes wavelet transform to differentiate described dtc signal more
Rate is decomposed, it is thus achieved that the wavelet coefficient of described dtc signal;
Step 107: described characteristic extracting module is according to the pulsation of the cogging torque signal of described tested magneto
Frequency, is modified described wavelet coefficient;
Step 108: described characteristic extracting module uses revised wavelet coefficient to carry out wavelet reconstruction, it is thus achieved that institute
State the cogging torque signal of tested magneto.
2. the measuring method of cogging torque of permanent magnet motor as claimed in claim 1, it is characterised in that described
Signal pre-processing module includes: voltage follower, signal amplification circuit, wave filter and the shaping being sequentially connected with
Circuit;Described step 102 specifically includes:
Step 201: the magnitude of voltage of described transducing signal is adjusted by described voltage follower, so that described electricity
The output voltage of pressure follower matches with input voltage;
Step 202: the transducing signal that described voltage follower is exported by described signal amplification circuit is amplified;
Step 203: the interference signal in the transducing signal after amplification process is filtered by described wave filter;
Step 204: filtered transducing signal is shaped as rectangular pulse signal by described shaping circuit, and provides
To data collecting card.
3. the measuring method of cogging torque of permanent magnet motor as claimed in claim 2, it is characterised in that described
Wave filter is the second order active low pass filter using hardware circuit to realize.
4. the measuring method of cogging torque of permanent magnet motor as claimed in claim 2, it is characterised in that described
Wave filter uses the mode of software filtering to be filtered transducing signal.
5. the measuring method of cogging torque of permanent magnet motor as claimed in claim 1, it is characterised in that described
Step 106 specifically includes:
Step 601: after described characteristic extracting module treats that the sample rate of described dtc signal meets sampling thheorem,
The total frequency band occupied by the signal collected is defined as SPACE V0, described total frequency band is 0~fs/2;Through a fraction
Xie Hou, by V0It is divided into low frequency subspace V1With high frequency subspace W1;, described V1Frequency band be 0~fs/ 4,
Described W1Frequency band is fs/ 4~fs/2;
Step 602: after two grades are decomposed, by described V1It is decomposed into low frequency subspace V2With high frequency subspace
W2, described V2Frequency band be 0~fs/ 8, described W2Frequency band be fs/ 8~fs/4;And so on, by frequency
Uniformly subdivision is: V0=V1⊕W1, V1=V2⊕W2..., Vj-1=Vj⊕Wj, therefore:
V0=W1⊕W2⊕W3......Wj⊕Vj
Wherein, each WjIt is reflection Vj-1The high frequency subspace of spacing wave details, VjIt is reflection Vj-1Spacing wave
The low frequency subspace of details, WjFor VjAt Vj-1The orthogonal complement space;
Step 603: by multiresolution analysis and orthogonal space resolution theory,Wherein J is
Arbitrarily yardstick, by signal x (t) ∈ L2(R) at space L2(R) upper launch, obtain following expression:
Wherein, Double-scaling equation is:
IfdJ+1, n=< fj, ψJ+1, n> and then decompose and obtain wavelet coefficient and be:
Wherein, k=0,1,2 ... n-1, represent translation position;The j frequency range to induction signal;cj+1,k, dj+1,kFor
Described wavelet coefficient;H (k) is low pass filter sampling response;G (k) is high-pass filter sampling response;
For scaling function;ψj,kT () is wavelet function.
6. the measuring method of cogging torque of permanent magnet motor as claimed in claim 1, it is characterised in that described
Step 107 comprises the following steps:
Step 701: according to rotating speed v and teeth groove quantity Z of described tested magneto, calculate described tested
Cogging torque ripple frequency f of magnetoc=v × Z/60;
Step 702: according to described dtc signal output frequency f and described cogging torque ripple frequency fc, select
Small echo;And determine number of plies n of wavelet decomposition, wherein n > 0;
Step 703: described dtc signal is carried out 1 wavelet transform arriving n-layer, decomposes and obtain each layer
Wavelet coefficient;
Step 704: retain and described cogging torque ripple frequency fcThe component of corresponding wavelet coefficient, and will
The component zero setting of the wavelet coefficient that remaining frequency range is corresponding, it is thus achieved that revised wavelet coefficient.
7. the measuring method of cogging torque of permanent magnet motor as claimed in claim 6, it is characterised in that described
Small echo is the western small echo of many shellfishes.
8. the measuring method of cogging torque of permanent magnet motor as claimed in claim 1, it is characterised in that described
Step 108 comprises the following steps:
Step 801: utilize the multi-resolution characteristics of small echo, searches the frequency corresponding to cogging torque ripple frequency section
Segment signal;
Step 802: order remaining frequency band signals in addition to the frequency band signals of described correspondence is zero, and process obtains new
Wavelet coefficient;
Step 803: utilize described wavelet coefficient that signal is reconstructed by below equation:
Wherein, cj,kFor cogging torque signal, the signal that reconstruct obtains is cogging torque signal.
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