CN109459618A - The online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance - Google Patents
The online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance Download PDFInfo
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Abstract
The online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance, belong to dc-link capacitance health status monitoring field, solves the problems, such as that the health status monitoring method of existing electrolytic capacitor is not suitable for electric drive system for electric vehicles dc-link capacitance.The quasi- online capacitance detection method: temporary dwelling period during electric automobile during traveling, to the d-axis of permanent magnet synchronous motor injection one doped with the low-frequency ac electric current signal of DC component.According to the bus current signal reconstruction dc-link capacitance current signal of the three-phase current signal of permanent magnet synchronous motor, inverter IGBT switching signal and inverter direct-flow side.It extracts DC bus-bar voltage signal and filters out DC component therein, filter out the DC component in dc-link capacitance current signal.To filtering out the DC bus-bar voltage signal after DC component and dc-link capacitance current signal carries out phase shift, and the capacitance of dc-link capacitance is calculated according to the signal after phase shift.
Description
Technical field
The present invention relates to a kind of capacitance detection methods of dc-link capacitance, belong to dc-link capacitance health status monitoring
Field.
Background technique
In recent years, with the rapid proliferation of electric car, it is more next that the safety and reliability of electric car receives people
More concerns.Power drive system is the major impetus source of electric car, and safety and reliability will directly affect vehicle
Safe operation.Dc-link capacitance is a weak ring in the important component and power electronic system of power drive system
Section.The failure of removal of dc-link capacitance will lead to the deterioration of power drive system performance, and power drive system is resulted even in when serious
It crashes.Therefore, be monitored to the health status of electric drive system for electric vehicles dc-link capacitance is to improve power drive system
Safety and reliability ensures that vehicle is safely operated.
Existing capacitor health status monitoring method is primarily directed to electrolytic capacitor, such method with electrolytic capacitor etc.
Series resistance value is imitated to evaluate the health status of electrolytic capacitor.However, in order to improve the reliability of system, existing electric drive trains
The dc-link capacitance of system generallys use the higher thin-film capacitor of reliability, the health status and equivalent series resistance of thin-film capacitor
The degree of correlation of resistance value is not high, highly relevant with the capacitance of thin-film capacitor.Therefore, existing capacitor health status monitoring method is uncomfortable
For electric drive system for electric vehicles dc-link capacitance.
Summary of the invention
The present invention is to solve the health status monitoring method of existing electrolytic capacitor not being suitable for electric drive system for electric vehicles
The problem of dc-link capacitance, proposes a kind of online capacitance detection side of standard of electric drive system for electric vehicles dc-link capacitance
Method.
Capacitance detection method includes: the standard online
Step 1: temporary dwelling period during electric automobile during traveling, mixes to the d-axis of permanent magnet synchronous motor injection one
The miscellaneous low-frequency ac electric current signal for having DC component；
Step 2: negative according to the three-phase current signal of permanent magnet synchronous motor and inverter IGBT switching signal reconstruct inverter
The bus output current signal of side is carried, and according to the bus output current signal of inverter load-side and the mother of inverter direct-flow side
Line current signal reconstruction dc-link capacitance current signal；
Step 3: extracting DC bus-bar voltage signal by single order high-pass filter, pass through the first Second Order Generalized Integrator
The DC component in DC bus-bar voltage signal is filtered out, dc-link capacitance electric current letter is filtered out by the second Second Order Generalized Integrator
DC component in number；
Step 4: by third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator to straight after filtering out DC component
It flows bus voltage signal and carries out phase shift, divided by the 5th Second Order Generalized Integrator and the 6th Second Order Generalized Integrator direct current is filtered out
Dc-link capacitance current signal after amount carries out phase shift；
Step 5: it is female to calculate direct current according to third Second Order Generalized Integrator~the 6th Second Order Generalized Integrator output signal
The capacitance of line capacitance.
As preferably, step 1 in the direct-axis current ring of permanent magnet synchronous motor by introducing ratio resonant controller
Mode, the current controller of permanent magnet synchronous motor is revised as PIR controller from PI controller, and pass through the current controller
Realize the injection of the low-frequency ac electric current signal doped with DC component；
Doped with the expression formula of the low-frequency ac electric current signal of DC component are as follows:
In formula,For the low-frequency ac electric current signal doped with DC component, I0For the amplitude of DC component, IhAnd ωhPoint
Not Wei low-frequency ac electric current signal amplitude and frequency, I0> Ih> 0；
The expression formula of PIR controller are as follows:
In formula, GcIt (s) is PIR controller, Kp、KiAnd KcIt is the control parameter of PIR controller.
As preferably, step 2 reconstruct inverter load-side bus output current signal expression formula are as follows:
In formula, iLFor the bus output current signal of inverter load-side, UhFor the d-axis alternating voltage of permanent magnet synchronous motor
The amplitude of signal,It is power-factor angle, R is the resistance value of permanent magnet synchronous motor phase resistance, udcFor DC bus-bar voltage signal.
As preferably, step 2 reconstruct dc-link capacitance current signal expression formula are as follows:
icap=idc-iL
In formula, icapFor dc-link capacitance current signal, idcFor the bus current signal of inverter direct-flow side.
As preferably, the first Second Order Generalized Integrator is using DC bus-bar voltage signal as its input signal, output
DC bus-bar voltage signal intermediate frequency rate is 2 ωhAC compounent；
Second Second Order Generalized Integrator exports DC bus electricity using dc-link capacitance current signal as its input signal
Capacitance current signal intermediate frequency rate is 2 ωhAC compounent；
DC bus-bar voltage signal intermediate frequency rate is 2 by third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator
ωhAC compounent as its input signal；
5th Second Order Generalized Integrator and the 6th Second Order Generalized Integrator are by frequency in dc-link capacitance current signal
For 2 ωhAC compounent as its input signal.
As preferably, the transmission function of Second Order Generalized Integrator are as follows:
In formula, v is the input signal of Second Order Generalized Integrator, vdAnd vqIt is the output signal of Second Order Generalized Integrator, k
For damped coefficient, 0 < k < 1；
First Second Order Generalized Integrator, the second Second Order Generalized Integrator, the 4th Second Order Generalized Integrator and the 6th second order are wide
Adopted integrator is all made of D (s) as its transmission function；
Third Second Order Generalized Integrator and the 5th Second Order Generalized Integrator are all made of Q (s) as its transmission function.
As preferably, step 5 calculates the capacitance of dc-link capacitance according to the following formula:
In formula, C is the capacitance of dc-link capacitance, vq,3、vd,4、vq,5And vd,6Respectively third Second Order Generalized Integrator~
The output signal of 6th Second Order Generalized Integrator.
The online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance of the present invention, electronic
Temporary dwelling period in vehicle traveling process, to the d-axis of permanent magnet synchronous motor injection one doped with the low-frequency ac of DC component
Current signal.Inverter load-side is reconstructed according to the three-phase current signal of permanent magnet synchronous motor and inverter IGBT switching signal
Bus output current signal, and according to the bus output current signal of inverter load-side and the bus current of inverter direct-flow side
Signal reconstruction dc-link capacitance current signal.DC bus-bar voltage signal is extracted by single order high-pass filter, passes through first
Second Order Generalized Integrator filters out the DC component in DC bus-bar voltage signal, filters out direct current by the second Second Order Generalized Integrator
DC component in bus capacitor current signal.By third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator to filtering out
DC bus-bar voltage signal after DC component carries out phase shift, passes through the 5th Second Order Generalized Integrator and the 6th second order improper integral
Device carries out phase shift to the dc-link capacitance current signal after filtering out DC component.According to third Second Order Generalized Integrator~6th
The output signal of Second Order Generalized Integrator calculates the capacitance of dc-link capacitance.Electric car electricity of the present invention drives as a result,
The online capacitance detection method of the standard of dynamic system dc bus capacitor is able to solve the health status monitoring method of existing electrolytic capacitor
Not the problem of not being suitable for electric drive system for electric vehicles dc-link capacitance.
Detailed description of the invention
It will hereinafter come based on the embodiments and with reference to the accompanying drawings to electric drive system for electric vehicles direct current of the present invention
The online capacitance detection method of the standard of bus capacitor is described in more detail, in which:
Fig. 1 is speed curve diagram of the electric car that refers to of embodiment under NEDC operating condition；
Fig. 2 is the equivalent circuit diagram for the capacitor that embodiment refers to；
Fig. 3 is the circuit diagram for the motor in electric automobile inverter that embodiment refers to；
The bus output current signal and motor phase of inverter load-side in the switch periods that Fig. 4 refers to for embodiment
The corresponding relationship of current signal；
Fig. 5 is the control block diagram of permanent magnet synchronous motor d-axis under the shutdown status that embodiment refers to；
Fig. 6 is the circuit diagram for the single order high-pass filter that embodiment refers to；
Fig. 7 is the structural block diagram for the Second Order Generalized Integrator that embodiment refers to；
Fig. 8 is the Second Order Generalized Integrator that refers to of embodiment in k=0.01, ωhBode diagram when=100 π；
Fig. 9 is the flow diagram for the dc-link capacitance capacitance detection method that embodiment refers to；
Figure 10 is the permanent magnet synchronous motor quadrature axis current i that embodiment refers toqIt is 0, direct-axis current idBe given as I0=10A,
Ih=9A, ωhDirect-axis current i when=30HzdInstructional waveform and response wave shape figure；
Figure 11 is the permanent magnet synchronous motor quadrature axis current i that embodiment refers toqIt is 0, direct-axis current idBe given as I0=10A,
Ih=9A, ωhI when=30HzdcResponse wave shape and iLCalculating waveform diagram；
Figure 12 is the permanent magnet synchronous motor quadrature axis current i that embodiment refers toqIt is 0, direct-axis current idBe given as I0=10A,
Ih=9A, ωhI when=30HzcapCalculating waveform, by the filtered dc-link capacitance current signal of Second Order Generalized Integrator
Middle frequency is 2 ωhAC compounent icap,2hIt is 2 ω with DC bus-bar voltage signal intermediate frequency ratehAC compounent udc,2hWaveform
Figure.
Specific embodiment
Hold below in conjunction with standard of the attached drawing to electric drive system for electric vehicles dc-link capacitance of the present invention is online
Value detection method is described further.
Embodiment: the present embodiment is explained in detail below with reference to Fig. 1~Figure 12.
The online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance described in the present embodiment, is applicable in
In dc-link capacitance be thin-film capacitor and motor is the electric drive system for electric vehicles of permanent magnet synchronous motor；
Capacitance detection method includes: the standard online
Step 1: temporary dwelling period during electric automobile during traveling, mixes to the d-axis of permanent magnet synchronous motor injection one
The miscellaneous low-frequency ac electric current signal for having DC component；
Step 2: negative according to the three-phase current signal of permanent magnet synchronous motor and inverter IGBT switching signal reconstruct inverter
The bus output current signal of side is carried, and according to the bus output current signal of inverter load-side and the mother of inverter direct-flow side
Line current signal reconstruction dc-link capacitance current signal；
Step 3: extracting DC bus-bar voltage signal by single order high-pass filter, pass through the first Second Order Generalized Integrator
The DC component in DC bus-bar voltage signal is filtered out, dc-link capacitance electric current letter is filtered out by the second Second Order Generalized Integrator
DC component in number；
Step 4: by third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator to straight after filtering out DC component
It flows bus voltage signal and carries out phase shift, divided by the 5th Second Order Generalized Integrator and the 6th Second Order Generalized Integrator direct current is filtered out
Dc-link capacitance current signal after amount carries out phase shift；
Step 5: it is female to calculate direct current according to third Second Order Generalized Integrator~the 6th Second Order Generalized Integrator output signal
The capacitance of line capacitance.
The step of the present embodiment one, in the direct-axis current ring of permanent magnet synchronous motor by introducing ratio resonant controller
The current controller of permanent magnet synchronous motor is revised as PIR controller from PI controller by mode, and real by the current controller
Now doped with the injection of the low-frequency ac electric current signal of DC component；
Doped with the expression formula of the low-frequency ac electric current signal of DC component are as follows:
In formula,For the low-frequency ac electric current signal doped with DC component, I0For the amplitude of DC component, IhAnd ωhPoint
Not Wei low-frequency ac electric current signal amplitude and frequency, I0> Ih> 0；
The expression formula of PIR controller are as follows:
In formula, GcIt (s) is PIR controller, Kp、KiAnd KcIt is the control parameter of PIR controller.
The expression formula of the bus output current signal for the inverter load-side that the step of the present embodiment two reconstructs are as follows:
In formula, iLFor the bus output current signal of inverter load-side, UhFor the d-axis alternating voltage of permanent magnet synchronous motor
The amplitude of signal,It is power-factor angle, R is the resistance value of permanent magnet synchronous motor phase resistance, udcFor DC bus-bar voltage signal.
The expression formula for the dc-link capacitance current signal that the step of the present embodiment two reconstructs are as follows:
icap=idc-iL
In formula, icapFor dc-link capacitance current signal, idcFor the bus current signal of inverter direct-flow side.
In the present embodiment, the first Second Order Generalized Integrator is using DC bus-bar voltage signal as its input signal, output
DC bus-bar voltage signal intermediate frequency rate is 2 ωhAC compounent；
Second Second Order Generalized Integrator exports DC bus electricity using dc-link capacitance current signal as its input signal
Capacitance current signal intermediate frequency rate is 2 ωhAC compounent；
DC bus-bar voltage signal intermediate frequency rate is 2 by third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator
ωhAC compounent as its input signal；
5th Second Order Generalized Integrator and the 6th Second Order Generalized Integrator are by frequency in dc-link capacitance current signal
For 2 ωhAC compounent as its input signal.
The transmission function of Second Order Generalized Integrator are as follows:
In formula, v is the input signal of Second Order Generalized Integrator, vdAnd vqIt is the output signal of Second Order Generalized Integrator, k
For damped coefficient, 0 < k < 1；
In the present embodiment, the first Second Order Generalized Integrator, the second Second Order Generalized Integrator, the 4th Second Order Generalized Integrator
D (s) is all made of as its transmission function with the 6th Second Order Generalized Integrator；
Third Second Order Generalized Integrator and the 5th Second Order Generalized Integrator are all made of Q (s) as its transmission function.
As preferably, step 5 calculates the capacitance of dc-link capacitance according to the following formula:
In formula, C is the capacitance of dc-link capacitance, vq,3、vd,4、vq,5And vd,6Respectively third Second Order Generalized Integrator~
The output signal of 6th Second Order Generalized Integrator.
The following detailed description of the online capacitance of standard of electric drive system for electric vehicles dc-link capacitance described in the present embodiment
The principle of detection method.
Quasi- on-line fault diagnosis feasibility analysis under electric automobile work condition:
Quasi- on-line fault diagnosis strategy be using equipment operation during the of short duration shutdown moment, using equipment own resource into
The offline diagnostic method of row fault diagnosis.This method be chiefly used in solar energy and wind-power electricity generation etc. have between discontinuous working characteristics
Application, without adding any diagnostic instrments.Compared with conventional offline diagnostic techniques, quasi- on-line fault diagnosis strategy has
Implement the advantages that simple, at low cost and real-time is high.Fig. 1 gives rate curve of the electric car under NEDC operating condition.According to
Fig. 1 is it is found that the operating condition of electric car is a kind of typical discontinuous operating condition.Therefore, quasi- on-line fault diagnosis strategy is very
It is suitble to apply on electric car.
Thin-film capacitor malfunction and failure mechanism and fault signature:
The equivalent circuit of capacitor is as shown in Figure 2.In figure, RESRAnd LESLThe respectively equivalent series resistance and equivalent string of capacitor
Join inductance.Since the working frequency of dc-link capacitance is usually lower, equivalent series inductance be can be ignored.DC bus electricity
The electrical characteristic of appearance is determined jointly by capacitance and equivalent series resistance resistance value.
Alminium electrolytic condenser and metal thin film capacitor are two kinds of most widely used dc-link capacitances.The mistake of alminium electrolytic condenser
Imitating mechanism is that electrolyte volatilization is reduced, and life characteristics usually react in the variation of equivalent series resistance resistance value.Therefore, big absolutely
The method for diagnosing faults of most alminium electrolytic condensers focuses on the test problems of equivalent series resistance resistance value.
Metal thin film capacitor is made of metal electrode and metallized film, and failure mechanism is entirely different with electrolytic capacitor.
The failure mechanism of metal thin film capacitor can be divided into excessive self-healing, oxidation deactivation and open circuit failure.Excessive self-healing is generally by capacitor
Manufacturing defect or mechanical damage cause, and when failure is serious, the bulk gas that excessive self-healing generates will lead to capacitance shell and expand
It splits.Oxidation deactivation is generally caused by the comprehensive function of the temperature of environment and humidity.Open circuit failure is then answered by electricity, heat and mechanical three kinds
Power comprehensive function causes.When the failure as caused by above-mentioned three kinds of failure mechanisms occurs, capacity loss increase, capacitor temperature will lead to
Rapid increase is spent, capacitor's capacity is decayed rapidly.In practical applications, the power density of motor in electric automobile driver is higher, heat
Load is larger, and therefore, compared to general industry application, the occurrence frequency of capacitive faults is higher, and fault progression speed is faster.
As the above analysis, the fault signature of metal thin film capacitor and the loss of capacitance are related.The loss of capacitor's capacity
Situation can be measured by capacitance loss rate CL, and CL can be calculated by following formula:
CL=(1-C/C0) × 100% (1)
In formula, C0For the initial capacitance of capacitor, C is the detection capacitance of capacitor.
Under normal circumstances, the capacitance of thin-film capacitor is with using slow-decay, as CL > 5%, it is believed that the thin-film capacitor longevity
Life exhausts.But in onboard system, the limitation being interfered with factors such as sensor accuracies, actual capacitor's capacity detection accuracy
It is lower.If being the decision condition of failure with CL > 5%, wrong diagnosis rate is higher.On the other hand, when thin-film capacitor breaks down, CL
Decaying is much larger than 5%.Therefore, the criterion of capacitive faults can suitably be relaxed.In the present embodiment, the failure of thin-film capacitor is sentenced
Determining principle is: as CL > 10%, capacitor is judged as failing.
According to formula (1) it is found that if the initial capacitance C of known capacitance0, then the current capacitance of capacitor need to be only detected, i.e.,
The condition monitoring and fault diagnosis of capacitor can be achieved.Therefore, the detection of capacitor's capacity is the base for realizing thin-film capacitor fault diagnosis
Plinth.
The testing principle of dc-link capacitance capacitance:
The circuit theory of motor in electric automobile inverter is as shown in Figure 3.Motor driver is equipped with electric current on current bus bar
Sensor and voltage sensor are equipped with phase current sensor in inverter outlet side.For the inspection for realizing dc-link capacitance capacitance
It surveys, needs to detect dc-link capacitance current signal icap.However, with the raising of inverter integrated level and answering for public busbar
With icapIt becomes difficult to measure, needs to reconstruct i by IGBT switching tube state and phase current sensorcap。
According to Fig.3, dc-link capacitance current signal icapExpression formula be
icap=idc-iL (2)
In formula, idcFor the bus current signal of inverter direct-flow side, iLElectric current letter is exported for the bus of inverter load-side
Number.
From the figure 3, it may be seen that idcIt can be detected by bus current sensor, iLCan not directly measure, but can by electric machine phase current with
IGBT switching signal reconstruction calculations obtain.Fig. 4 gives i in a switch periodsLWith the corresponding relationship of electric machine phase current waveform.
The i of the present embodimentLTake the average value of a switch periods load-side current integration, then as shown in Figure 4 its calculation formula is:
In formula, ia、ibAnd icFor electric machine phase current, Ta、TbAnd TcIt is the upper tube turn-on time of three-phase IGBT switching tube, TsFor
Switch periods.
After the detection for solving dc-link capacitance electric current, needs to design the output signal of inverter, generate DC bus
Harmonic component containing capacitor's capacity information.In permanent magnet synchronous motor stalling, the exchange of a low frequency is injected to motor d-axis
Current signal, and motor quadrature axis current is enabled to remain 0.
The expression formula of the low-frequency ac electric current signal of injection is as follows:
id=Ihcosωht (4)
In formula, idFor low-frequency ac electric current signal, IhAnd ωhThe respectively amplitude and frequency of low-frequency ac electric current signal.
The voltage of permanent magnet synchronous motor can be expressed as:
In formula, udFor the d-axis ac voltage signal of permanent magnet synchronous motor, uqFor the quadrature axis alternating voltage of permanent magnet synchronous motor
Signal, UhFor the amplitude of the d-axis ac voltage signal of permanent magnet synchronous motor,It is power-factor angle.
At this point, the three-phase current and three-phase voltage of permanent magnet synchronous motor are respectively as follows:
Ta、TbAnd TcExpression formula it is writeable are as follows:
In formula, udcFor DC bus-bar voltage signal, u0(t) be SVPWM modulation strategy injection zero-sequence component.
Formula (6), formula (7) and formula (8) are substituted into formula (3), then iLAnalytical expression are as follows:
According to above-mentioned analysis it is found that the bus output current signal i of inverter load-sideLIn there are frequency be 2 ωhFriendship
Flow harmonic component.Simultaneously as the filter action of dc-link capacitance, the voltage and current of dc-link capacitance also deposits correspondence
It is 2 ω in frequencyhRipple component.Therefore, the impedance value of this ripple component approximate calculation bus capacitor can be used, it may be assumed that
In formula, ZcFor the impedance of dc-link capacitance, udc,2hIt is 2 ω for DC bus-bar voltage signal intermediate frequency ratehExchange
Component, icap,2hTo be 2 ω by frequency in dc-link capacitance current signalhAC compounent.
It is smaller in the equivalent series resistance resistance value of middle low frequency band, thin-film capacitor, it can be ignored.Therefore, capacitor holds
Value can approximate calculation are as follows:
After dc-link capacitance capacitance has been calculated, CL can be calculated according to formula (1), judge whether dc-link capacitance loses
Effect.
Dc-link capacitance capacitance detection method based on Second Order Generalized Integrator:
Need to realize the harmonic wave note of current of electric to complete the detection of dc-link capacitance capacitance according to above-mentioned analysis
Enter, two processes of harmonic wave separation of DC bus-bar voltage and dc-link capacitance electric current.
Fig. 5 is the control block diagram of permanent magnet synchronous motor d-axis under shutdown status, GcIt (s) is motor current controller.For reality
The harmonic injection of existing current of electric introduces ratio resonant controller in direct-axis current ring, PI controller is revised as PIR control
Device, it may be assumed that
In formula, Kp、KiAnd KcIt is the control parameter of PIR controller.
If injection waveform is pure AC compounent, Injection Current respectively corresponds motor in positive half period and negative half-cycle and increases magnetic
Area and weak magnetic area, are influenced by magnetic saturation effect, and output voltage increases magnetic region and the waveform of weak magnetic area is not fully symmetrical, are caused
Output voltage distortion.Meanwhile being influenced when alternating current zero passage by IGBT dead time, it may appear that obvious distortion.To improve electricity
The distortion of pressure and electric current, Injection Current can suitably increase DC component, and Injection Current is made to increase magnetic region work, each mutually electricity always
Stream also no longer zero passage, it may be assumed that
In formula,For the low-frequency ac electric current signal doped with DC component, I0For the amplitude of DC component, IhAnd ωhPoint
Not Wei low-frequency ac electric current signal amplitude and frequency, I0> Ih> 0；
At this point, iLAnalytical expression are as follows:
In formula, R is the resistance value of permanent magnet synchronous motor phase resistance.
According to formula (14) it is found that working as I0When not being 0, iLIn will include apparent fundametal compoment.But due to current sensor
There are drift errors, and there are errors between system given DC component and real response, lead to I0Measured value inaccuracy, because
This fundametal compoment is not used to the detection of dc-link capacitance capacitance.
To extract DC bus voltage harmonics, increases a single order high-pass filter and extract DC bus-bar voltage ripple, filter
DC bus-bar voltage after wave is denoted as udc,hf, ChfAnd RhfThe respectively capacitor's capacity and resistance of single order high-pass filter, such as
Shown in Fig. 6.
For the separation of the harmonic component of realization DC bus-bar voltage and dc-link capacitance electric current, second order improper integral is introduced
For device for filtering, structural block diagram is as shown in Figure 7.Its transmission function are as follows:
In formula, v is the input signal of Second Order Generalized Integrator, vdAnd vqIt is the output signal of Second Order Generalized Integrator, k
For damped coefficient, 0 < k < 1；
K value determines the filter effect of Second Order Generalized Integrator, and k is smaller, and the bandwidth of Second Order Generalized Integrator is narrower, frequency-selecting
Characteristic is better, but response speed is slack-off, and the time that filter reaches stable state is elongated.Therefore, k value should be adjusted suitably according to actual needs
It is whole.
Second Order Generalized Integrator is a kind of typical bandpass filter.Fig. 8 gives Second Order Generalized Integrator in k=
0.01, ωhBode diagram when=100 π.It can be seen from the figure that Second Order Generalized Integrator has stronger selecting frequency characteristic, to spy
Determining the harmonic wave except frequency has stronger inhibiting effect, the screening of suitable specific frequency harmonic wave.
In sampled signal, icapIn contain DC component, be mainly derived from the drift error of each current sensor,
This error will affect the detection accuracy of dc-link capacitance capacitance.Therefore, filter has to filter out direct current point in sampled signal
Amount.D (s) and Q (s) can be realized the extraction of harmonic component, but Q (s) cannot be completely eliminated DC component.Therefore, this implementation
Example uses filter of the D (s) as signal.Meanwhile after completing harmonic wave separation, the present embodiment still uses Second Order Generalized Integrator
Calculate the virtual value of AC harmonic.The process of dc-link capacitance capacitance detection method is as shown in Figure 9.In figure, D1(s)、D2(s)、
Q3(s)、D4(s)、Q5(s) and D6It (s) is respectively the first Second Order Generalized Integrator~the 6th Second Order Generalized Integrator,For direct current mother
The approximate calculation value of dc-link capacitance capacitance is considered as dc-link capacitance by the approximate calculation value of line capacitance capacitance, the present embodiment
Capacitance.The third Second Order Generalized Integrator of the present embodiment and the 4th Second Order Generalized Integrator, the 5th Second Order Generalized Integrator and
Six Second Order Generalized Integrators are mainly used for phase shift, convenient for calculating udc,2hAnd icap,2hAmplitude.
Experimental result and analysis:
For the feasibility for verifying dc-link capacitance capacitance detection method, relevant experiment has been carried out on experiment porch.
Permanent magnet synchronous motor in experiment using a 10kW is as model machine.Dc-link capacitance selects B25620B0557K881 type
Number metal thin film capacitor, only nominal capacitance is 550 μ F for capacitor list, using two capacitor parallel connections as motor driven system in experiment
The bus Support Capacitor of system.The main control chip of power drive system uses the dsp chip of TMS320F28335 model, and interrupt cycle is
10k.The model AD7606 of the AD sampling A/D chip of system, sampling precision are 16.The model LT58-S7 of current sensor.
In terms of filtering parameter setting, single order high-pass filter capacitor and resistance parameter are respectively Chf=0.1 μ F, Rhf=680k Ω is cut
Only frequency is 2.34Hz.First Second Order Generalized Integrator~the 6th Second Order Generalized Integrator parameter is consistent, damping system
Number k=0.01.
In experiment, permanent magnet synchronous motor quadrature axis current i is enabledqIt is 0, direct-axis current idBe given as I0=10A, Ih=9A.Figure
10 give ωhI when=30HzdInstructional waveform and response wave shape.According to experimental result it is found that idInstructional waveform and response
Waveform is almost the same, this shows after using resonant controller, idResponse can follow using sinusoidal given reference waveform, it is real
The error free control of given frequency harmonic is showed.
Figure 11 gives ωhI when=30HzdcResponse wave shape and iLCalculating waveform.
Figure 12 gives ωhI when=30HzcapCalculating waveform, by the filtered DC bus of Second Order Generalized Integrator
Capacitance current signal intermediate frequency rate is 2 ωhAC compounent icap,2hIt is 2 ω with DC bus-bar voltage signal intermediate frequency ratehExchange point
Measure udc,2hWaveform.
From experimental waveform it is found that due to given certain DC component I0, result in icapIn there is apparent fundamental wave
Component, the theoretical analysis result of this coincidence formula (14).As can be seen from Figure 12, after Second Order Generalized Integrator filters, system is obtained
Relatively stable icap,2hAnd udc,2hWaveform, and sine degree is preferable, and this is the result shows that Second Order Generalized Integrator is real well
The function of filtering is showed.From the point of view of the phase of waveform, icap,2hThe advanced u of phasedc,2h, leading angle meets substantially close to 90 °
The impedance operator of capacitor.
Table 1 gives ωhThe testing result of dc-link capacitance capacitance and actual direct current are female under different harmonic frequencies
Line capacitance capacitance measurement result, and calculate systematic error.Wherein, the measured value of dc-link capacitance using LCR tester into
Row measurement, the correspondence measurement frequency of LCR are 2 ωh.From the point of view of measurement result is compared with testing result, detection error is on 2% left side
The right side, testing result is more accurate, and data basis can be provided for the fault diagnosis of metal thin film capacitor, evaluates metal thin film capacitor
Health status.
1 capacitance detecting value of table and measured value
Although describing the present invention herein with reference to specific embodiment, it should be understood that, these realities
Applying example only is the example of principles and applications.It should therefore be understood that can be permitted exemplary embodiment
More modifications, and can be designed that other arrangements, without departing from spirit of the invention as defined in the appended claims and
Range.It should be understood that different appurtenances can be combined by being different from mode described in original claim
It is required that and feature described herein.It will also be appreciated that the feature in conjunction with described in separate embodiments can be used at it
In his embodiment.
Claims (7)
1. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance, which is characterized in that the standard exists
Line capacitance detection method is thin-film capacitor suitable for dc-link capacitance and motor is the electric car electricity of permanent magnet synchronous motor
Drive system；
Capacitance detection method includes: the standard online
Step 1: temporary dwelling period during electric automobile during traveling, to the d-axis of permanent magnet synchronous motor injection one doped with
The low-frequency ac electric current signal of DC component；
Step 2: reconstructing inverter load-side according to the three-phase current signal of permanent magnet synchronous motor and inverter IGBT switching signal
Bus output current signal, and according to the bus of the bus output current signal of inverter load-side and inverter direct-flow side electricity
Flow signal reconstruction dc-link capacitance current signal；
Step 3: extracting DC bus-bar voltage signal by single order high-pass filter, filtered out by the first Second Order Generalized Integrator
DC component in DC bus-bar voltage signal is filtered out in dc-link capacitance current signal by the second Second Order Generalized Integrator
DC component；
Step 4: female to the direct current after filtering out DC component by third Second Order Generalized Integrator and the 4th Second Order Generalized Integrator
Line voltage signal carry out phase shift, by the 5th Second Order Generalized Integrator and the 6th Second Order Generalized Integrator to DC component is filtered out after
Dc-link capacitance current signal carry out phase shift；
Step 5: calculating DC bus electricity according to third Second Order Generalized Integrator~the 6th Second Order Generalized Integrator output signal
The capacitance of appearance.
2. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as described in claim 1,
It is characterized in that, step 1, will forever by way of introducing ratio resonant controller in the direct-axis current ring in permanent magnet synchronous motor
The current controller of magnetic-synchro motor is revised as PIR controller from PI controller, and by the current controller realize doped with
The injection of the low-frequency ac electric current signal of DC component；
Doped with the expression formula of the low-frequency ac electric current signal of DC component are as follows:
In formula,For the low-frequency ac electric current signal doped with DC component, I0For the amplitude of DC component, IhAnd ωhRespectively
The amplitude and frequency of low-frequency ac electric current signal, I0>Ih>0；
The expression formula of PIR controller are as follows:
In formula, GcIt (s) is PIR controller, Kp、KiAnd KcIt is the control parameter of PIR controller.
3. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as claimed in claim 2,
It is characterized in that, the expression formula of the bus output current signal of the inverter load-side of step 2 reconstruct are as follows:
In formula, iLFor the bus output current signal of inverter load-side, UhFor the d-axis ac voltage signal of permanent magnet synchronous motor
Amplitude,It is power-factor angle, R is the resistance value of permanent magnet synchronous motor phase resistance, udcFor DC bus-bar voltage signal.
4. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as claimed in claim 3,
It is characterized in that, the expression formula of the dc-link capacitance current signal of step 2 reconstruct are as follows:
icap=idc-iL
In formula, icapFor dc-link capacitance current signal, idcFor the bus current signal of inverter direct-flow side.
5. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as claimed in claim 4,
It is characterized in that, the first Second Order Generalized Integrator exports DC bus-bar voltage using DC bus-bar voltage signal as its input signal
Signal intermediate frequency rate is 2 ωhAC compounent；
Second Second Order Generalized Integrator exports dc-link capacitance electricity using dc-link capacitance current signal as its input signal
Stream signal intermediate frequency rate is 2 ωhAC compounent；
DC bus-bar voltage signal intermediate frequency rate is 2 ω by third Second Order Generalized Integrator and the 4th Second Order Generalized IntegratorhFriendship
Flow component is as its input signal；
Frequency in dc-link capacitance current signal is 2 ω by the 5th Second Order Generalized Integrator and the 6th Second Order Generalized Integratorh
AC compounent as its input signal.
6. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as claimed in claim 5, two
The transmission function of rank Generalized Integrator are as follows:
In formula, v is the input signal of Second Order Generalized Integrator, vdAnd vqIt is the output signal of Second Order Generalized Integrator, k is resistance
Buddhist nun's coefficient, 0 < k < 1；
It is characterized in that, the first Second Order Generalized Integrator, the second Second Order Generalized Integrator, the 4th Second Order Generalized Integrator and the 6th
Second Order Generalized Integrator is all made of D (s) as its transmission function；
Third Second Order Generalized Integrator and the 5th Second Order Generalized Integrator are all made of Q (s) as its transmission function.
7. the online capacitance detection method of the standard of electric drive system for electric vehicles dc-link capacitance as claimed in claim 6,
It is characterized in that, step 5 calculates the capacitance of dc-link capacitance according to the following formula:
In formula, C is the capacitance of dc-link capacitance, vq,3、vd,4、vq,5And vd,6Respectively third Second Order Generalized Integrator~6th
The output signal of Second Order Generalized Integrator.
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