CN110601515B - Filtering capacitor current sensorless control device of three-phase DC-AC converter - Google Patents

Filtering capacitor current sensorless control device of three-phase DC-AC converter Download PDF

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CN110601515B
CN110601515B CN201811131473.XA CN201811131473A CN110601515B CN 110601515 B CN110601515 B CN 110601515B CN 201811131473 A CN201811131473 A CN 201811131473A CN 110601515 B CN110601515 B CN 110601515B
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filter capacitor
phase
state variable
current
voltage
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CN110601515A (en
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杨宗振
小西义弘
谢旼儒
黄淑萱
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Industrial Technology Research Institute ITRI
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters

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Abstract

The invention provides a sensorless control method of filter capacitor current for a three-phase DC-AC converter for a state observer, which comprises the following steps: receiving a direct current link voltage of the three-phase direct current-alternating current converter at the current sampling time; receiving a first phase filter capacitor voltage actual value, a second phase filter capacitor voltage actual value and a third phase filter capacitor voltage actual value of the three-phase DC-AC converter at the current sampling time; and outputting a filter capacitor current state variable by a state observer, wherein the filter capacitor current state variable is a current predicted value of the next sampling time, and the filter capacitor current state variable is an average current value without ripple.

Description

Filtering capacitor current sensorless control device of three-phase DC-AC converter
Technical Field
The invention relates to a sensorless control device and a method for filter capacitor current of a three-phase DC-AC inverter for a state observer.
Background
There are various control methods for a DC-AC converter (DC-AC inverter), and among these control methods, the controlled current type mainly includes AC filter inductor current, AC filter capacitor current, or load current.
For a three-phase dc-ac converter system, the overall comparison of the ac filter inductor current control or the ac filter capacitor current control is as follows (both sensors are used). Under the control of AC filter inductance current sensing, total harmonic distortion (total harmonic distortion) compensation is poor; the system dynamic response is slow; the linear load control performance is excellent; the nonlinear load control performance is poor; at least two phase current detecting elements are required; the current detection device needs to use a high bandwidth device (high cost). Under the current sensing control of the AC filter capacitor, the total harmonic distortion compensation is better; the system dynamic response is fast; the linear load control performance is excellent; the nonlinear load control performance is better; at least two phase current detecting elements are required; the current detection device can be a low bandwidth device (low cost).
The detection method of the common ac filter capacitor current includes: direct detection and indirect detection. The direct detection of the ac filter capacitor current uses a hardware detection circuit, the magnitude of the ac filter capacitor current is determined by the impedance value of the filter capacitor, the impedance of the filter capacitor is usually small, and therefore the magnitude of the ac filter capacitor current is also small, so that a cheaper detection element can be used. However, the ac filter capacitor current has a ripple component, and a filter circuit is necessary to obtain a better signal, but the filter circuit has a signal delay problem.
In addition, there are two methods for indirectly detecting the ac filter capacitor current, one is to detect the ac inductor current and the load current by a hardware circuit, and the difference between the two is the ac filter capacitor current.
Among the three-phase converters, forced-air-cooled converters have switching frequencies of about 5kHz to 10kHz, for example: the uninterruptible power system has high control instruction efficiency and quick control response. In contrast, the switching frequency of a high power natural cooling type converter is about 1kHz to 3kHz, for example: the switching frequency of the power supply of the rail car is low, the control instruction efficiency is low, and the control response is slow. Therefore, for high power natural cooling converters, the improvement of energy efficiency becomes a technical key, and further improvement of controller performance is required.
Disclosure of Invention
An embodiment of the present disclosure provides a sensorless control method for filter capacitor current of a three-phase dc-ac converter by a state observer, including: receiving a direct current link voltage of the three-phase direct current-alternating current converter at the current sampling time; receiving a first phase filter capacitor voltage actual value, a second phase filter capacitor voltage actual value and a third phase filter capacitor voltage actual value of the three-phase DC-AC converter at the current sampling time; and outputting a filter capacitor current state variable by a state observer, wherein the filter capacitor current state variable is a current predicted value of the next sampling time, and the filter capacitor current state variable is an average current value without ripple.
An embodiment of the present disclosure provides a sensorless filter capacitor current control apparatus for a three-phase dc-ac converter, including: the chip comprises a state observer, wherein the state observer is used for capturing a direct current link voltage, a first-phase filter capacitor voltage actual value, a second-phase filter capacitor voltage actual value and a third-phase filter capacitor voltage actual value of the three-phase DC-AC converter at the current sampling time, and the state observer is used for outputting a filter capacitor current state variable at the next sampling time, and the filter capacitor current state variable is an average current value without ripple and is a current predicted value.
Drawings
Fig. 1 is a circuit diagram illustrating a three-phase dc-to-ac converter according to some embodiments.
FIG. 2 illustrates a state observer control block, according to some embodiments.
Fig. 3 is a control flow diagram (phase element) illustrating an off-grid mode according to some embodiments.
Fig. 4 is a control flow diagram (line element) illustrating an off-grid mode according to some embodiments.
FIG. 5 is a control flow diagram (D-Q axis elements) illustrating an off-grid mode according to some embodiments.
FIG. 6 is a flow diagram illustrating a method of filtered capacitive current sensorless control using a state observer, according to some embodiments.
Fig. 7 is a waveform diagram illustrating ac filter capacitor voltages of a phase element state observer, according to some embodiments.
Fig. 8 is a waveform diagram illustrating ac filter capacitor currents for a phase element state observer, according to some embodiments.
Fig. 9 is a waveform diagram illustrating ac filter capacitor voltages for a line element state observer, according to some embodiments.
Fig. 10 is a waveform diagram illustrating ac filter capacitance current of a line element state observer, according to some embodiments.
FIG. 11 is a waveform diagram illustrating AC filter capacitor voltages for a D-Q axis elemental state observer, according to some embodiments.
Fig. 12 is a waveform diagram illustrating ac filter capacitance currents for a D-Q axis elemental state observer, according to some embodiments.
[ Main element ]
D1～D6Parasitic diode Cdc1、Cdc2DC capacitor
Lf、Lfa、Lfb、LfcFilter inductor Cf、Cfa、Cfb、CfcFilter capacitor
EdDC link voltage vIaa ac voltage
vIbb ac voltage vIcc.C. AC voltage
iIaa alternating current iIbb alternating current
iIcc alternating current vLfaa phase filter inductance voltage
vLfbb-phase filter inductance voltage vLfcc-phase filter inductance voltage
iCaa AC filter capacitor current iCbb AC filter capacitor current
iCcc AC filter capacitor current vCaa AC filter capacitor voltage
vCbb AC filter capacitor voltage vCcc AC filter capacitor voltage
iLaa phase load current iLbb phase load current
iLcc-phase load current vnNeutral point voltage of capacitor
uaa phase modulation factor vDaa phase interference voltage
ωfFilter angular frequency T sample period
Q1～Q6Switching element 20 shapeState observer control block
21 control block 22, 24 adder
23 subtracter
u (k) discrete values of system modulation factors x (k), x (k +1)
ua(k) a phase modulation factor K gain matrix
ub(k) b phase modulation factor uc(k) c phase modulation factor
vIabab line ac voltage uabab line modulation factor
vCabab line ac filter capacitor voltage iIabab line ac current
iLabab line load current iCabab line ac filter capacitor current
uab(k) ab line modulation factor ubc(k) bc line modulation factor
uca(k) ca line modulation factor ACR current controller
AVR Voltage controller iIdD-axis alternating current
iIqQ-axis alternating current vIdD-axis alternating voltage
vIqQ-axis alternating voltage vCdD-axis AC filter capacitor voltage
vCqQ-axis AC filter capacitor voltage iCdD-axis AC filter capacitor current
iCqQ-axis AC filter capacitor current iCdxD-axis AC filter capacitor current
iCqxQ-axis AC filter capacitor current vDdD-axis disturbance voltage
vDqQ-axis disturbance voltage iLdD axis load current
iLqQ-axis load current vDdxD-axis disturbance voltage
vDqxQ-axis disturbance voltage udD-axis modulation factor
uqQ-axis modulation factor ud(k) D-axis modulation factor
uq(k) Q-axis modulation factor
Ad、Bd、CdCoefficient matrix 25Z-1Square block
Figure BDA0001813664820000041
State variable vC(k) Actual value of filter capacitor voltage
Figure BDA0001813664820000042
Filter capacitor voltage state variable 26BdCoefficient matrix block
27AdCoefficient matrix block 28CdCoefficient matrix block
29K gain matrix block
31 state observer 32, 33 subtracter
34 adder
35 divider
41 state observer 42, 43 subtracter
45 adder
46 divider 51 state observer
52. 53 subtractor 55 divider
54 adder
61-63 step 71 predicted value of AC filter capacitor voltage
72 actual value of ac filter capacitor voltage 73 actual value of ac filter capacitor current
74 AC filter capacitor current predicted value 75 AC filter capacitor voltage predicted value
Voltage actual value of 76 ac filter capacitor 77 ac filter capacitor current actual value
78 AC filter capacitor current prediction value 81 AC filter capacitor voltage prediction value
82 actual value of ac filter capacitor voltage 83 actual value of ac filter capacitor current
84 AC filter capacitor current predicted value K1、K2、K3Gain element
vCa(k)、vCaActual voltage value of (k +1) a-phase filter capacitor
vCb(k)、vCbActual voltage value of (k +1) b-phase filter capacitor
vCc(k)、vCcActual value of (k +1) c-phase filter capacitor voltage
iCa(k)、iCaActual value of (k +1) a-phase filter capacitor current
vDa(k)、vDa(k +1) a-phase disturbance electric voltage margin value
vCab(k+1)、vCab(k) ab line filter capacitor voltage actual value
vCbc(k) Actual voltage value of bc line filter capacitor
vCca(k) The actual voltage value of the filter capacitor of the ca line
iCab(k+1)、iCab(k) ab line filter capacitance current actual value
vDab(k+1)、vDab(k) ab line disturbance voltage actual value
vCd(k+1)、vCd(k) D-axis filter capacitor voltage actual value
iCd(k+1)、iCd(k) D-axis filter capacitor current actual value
vDd(k+1)、vDd(k) Actual value of D-axis disturbance voltage
vCq(k) Actual value of Q-axis filter capacitor voltage
vC *Filter capacitor voltage reference command value
Figure BDA0001813664820000051
a phase filter capacitor voltage state variable
Figure BDA0001813664820000052
b-phase filter capacitor voltage state variable
Figure BDA0001813664820000053
c-phase filter capacitor voltage state variable
Figure BDA0001813664820000054
ab line filter capacitor voltage state variable
Figure BDA0001813664820000061
bc line filter capacitor voltage state variable
Figure BDA0001813664820000062
ca line filter capacitor voltage state variable
Figure BDA0001813664820000063
D-axis filter capacitor voltage state variable
Figure BDA0001813664820000064
Q-axis filter capacitor voltage state variable
Figure BDA0001813664820000065
a-phase filter capacitor current state variable
Figure BDA0001813664820000066
b-phase filter capacitor current state variable
Figure BDA0001813664820000067
c-phase filter capacitor current state variable
Figure BDA0001813664820000068
ab line filter capacitance current state variable
Figure BDA0001813664820000069
bc line filter capacitor current state variable
Figure BDA00018136648200000610
ca line filter capacitor current state variable
Figure BDA00018136648200000611
D-axis filter capacitor current state variable
Figure BDA00018136648200000612
Q-axis filter capacitor current state variable
iC *Filter capacitor current reference command value
Figure BDA00018136648200000613
a phase disturbance voltage state variable
Figure BDA00018136648200000614
b-phase disturbance voltage state variable
Figure BDA00018136648200000615
c-phase disturbance voltage state variable
Figure BDA00018136648200000616
ab line disturbance voltage state variable
Figure BDA00018136648200000617
bc line disturbance voltage state variable
Figure BDA00018136648200000618
ca line disturbance voltage state variable
Figure BDA00018136648200000619
D-axis disturbance voltage state variable
Figure BDA00018136648200000620
Q-axis disturbance voltage state variable
Figure BDA00018136648200000621
Feedforward voltage state variable
vcontrol *Voltage control value
vpwm_cmdPulse width modulation comparison value
vDbb-phase interference voltage
vDcc-phase interference voltage
Detailed Description
The invention provides an alternating current filter capacitor current control device and a method, belongs to an indirect detection mode, and adopts a sensorless state observer which is applied to a three-phase direct current-alternating current converter (3-phase DC-AC inverter) system, wherein control elements can be divided into phase element control, line element control and D-Q axis element control. According to the invention, the time domain state equation of the alternating current filter capacitor voltage, the alternating current filter capacitor current and the disturbance voltage is obtained through circuit principle analysis, and then the discrete equation of the alternating current filter capacitor voltage, the alternating current filter capacitor current and the disturbance voltage is obtained through a time domain transformation discrete function mode, so that the realization of digital control is facilitated. The control of the invention is a prediction algorithm, which can obtain the predicted value of the next sampling time, reduce the error of the sampling time and improve the performance of the whole system. The device and the method provided by the invention can be used universally by only detecting the alternating current filter capacitor voltage and the direct current link voltage at the current sampling time, acquiring the predicted values of the alternating current filter capacitor voltage, the alternating current filter capacitor current and the disturbance voltage at the next sampling time by using the state observer, and converting the input parameters according to the phase elements, the line elements and the D-Q axis elements. In addition, the predicted value of the alternating current filter capacitor current is average current and has no ripple, and the alternating current filter capacitor current can be detected without a hardware sensor, so that the number of elements and the cost can be reduced.
In comparison of a three-phase dc-to-ac converter system with a single-phase dc-to-ac converter system: the power level requirements of the single-phase system are low; controlling the number of phases to be single phase; the parameters are less, and the control difficulty is lower; phase sequence control is not required; single phase loads may be supplied, for example: a fan or a lighting system. The power level requirement of the three-phase system is high; controlling the number of phases to be three phases; the parameters are more, and the difficulty of controlling the parameters is more difficult; phase difference of 120 degrees, phase sequence control is required; single phase loads or supplying three phase loads may be supported, for example: a refrigeration air conditioner, a motor load, or a combination of a refrigeration air conditioner unit, an electrical appliance lighting device, and an exhaust fan for a rail vehicle. The embodiment of the invention aims to improve the efficiency of a three-phase DC-AC converter system and reduce the circuit cost.
The overall comparison of the filter capacitor current control method using a sensing element or the filter capacitor current control method without a sensing element for a three-phase dc-ac converter system is as follows (the same control method, the latter without using a sensor). The signal controlled by the filter capacitor current of the sensing element has ripple component, and an additional hardware circuit is needed to obtain the average current value; a hardware filter circuit delay phenomenon exists; the signal processing control lags behind at least one sampling period; two phase current detection elements are required. The signal of the filter capacitor current control without the sensing element has no ripple component and can obtain the average current value; no hardware filter circuit delay phenomenon exists; signal processing control predictive control; phase current detecting elements are not required.
FIG. 1 illustrates a three-phase DC-to-AC converter 10 according to some embodiments0. The three-phase dc-ac converter 100 includes six switching elements Q1～Q6Two capacitors Cdc1、Cdc2Three filter inductors Lfa、Lfb、Lfc(the three values are equal and are also equal to the subsequent filter inductance LfTherefore L isf＝Lfa＝Lfb＝Lfc) And three filter capacitors Cfa、Cfb、Cfc(the three values are equal and are also equal to the subsequent filter capacitor CfTherefore, C isf＝Cfa＝Cfb＝Cfc) Parasitic diode D1～D6Matched switching element Q1～Q6. Each two switching elements constituting an independent phase, switching element Q1、Q2The switching elements Q3 and Q4 form the a phase, the switching elements Q5 and Q6 form the b phase, and the switching elements Q5 and Q6 form the c phase. The DC link capacitor is composed of two capacitors Cdc1、Cdc2Are connected in series. Three filter inductors Lfa、Lfb、LfcAnd three filter capacitors Cfa、Cfb、CfcThree filter inductors L forming a filter circuitfa、Lfb、LfcRespectively connected with a phase, b phase and C phase, and three filter capacitors Cfa、Cfb、CfcThen respectively connecting three filter inductors Lfa、Lfb、Lfc. Taking phase a as an example, the filter inductor LfaIs connected to the switching element Q1、Q2Between, filter inductance LfaThe other end of the first capacitor is connected with a filter capacitor CfaB, c phase filter inductance Lfb、LfcAnd a filter capacitor Cfb、CfcAnd so on. In addition, EdThe dc link voltage is the voltage across the terminals 12and 13 (voltage-drop across 12and 13), which is equivalent to the voltage across the dc link capacitance. v. ofIaIs a alternating voltage (switching element Q) of the three-phase DC-AC converter 1001、Q2Node voltage in between); v. ofIbIs b AC voltage (switching element Q)3、Q4Node voltage in between); v. ofIcFor c.C. alternating voltage (switching element Q)5、Q6Node voltage in between). i.e. iIaIs the a ac current of the three-phase dc-ac converter 100; i.e. iIbIs b alternating current; i.e. iIcIs a c-phase alternating current. v. ofCaFor a phase AC filter capacitor voltage (a phase filter capacitor C)faCross pressure of); v. ofCbFor b-phase ac filter capacitor voltage (b-phase filter capacitor C)fbCross pressure of); v. ofCcFor C-phase ac filter capacitor voltage (C-phase filter capacitor C)fcCross pressure of (d). i.e. iCaA, alternating current filter capacitor current; i.e. iCbB, alternating current filter capacitor current; i.e. iCcIs a c-phase ac filter capacitor current. i.e. iLaIs a phase load current; i.e. iLbIs b-phase load current; i.e. iLcIs the c-phase load current. v. ofnIs the neutral point voltage of the capacitor (capacitor).
In one embodiment, the following is a process for deriving a, b, and c-phase state observer equations with reference to the voltage and current parameters of FIG. 1. First, the equation of the a-phase observer is derived, and the relationship can be obtained by the circuit principle as shown in formula (1) and formula (2).
Figure BDA0001813664820000081
Figure BDA0001813664820000082
The parameters are respectively: a AC voltage v of the three-phase DC-AC converter 100Ia(ii) a a-phase filter inductance voltage vLfa(ii) a a AC filter capacitor voltage vCa(ii) a Voltage v at neutral point of capacitorn(ii) a a phase filter inductance voltage relation
Figure BDA0001813664820000091
a alternating current iIa(ii) a a phase load current iLa(ii) a a AC filter capacitor current iCa(ii) a a phase filter capacitance current relation
Figure BDA0001813664820000092
Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) The above-mentioned are continuous physical quantities in this case, except for constant values.
The equations (1) and (2) are expressed as equation of state, as shown in equations (3) and (4), where u isaIs a phase Modulation Index (Modulation Index), EdIs a dc link voltage.
Figure BDA0001813664820000093
Figure BDA0001813664820000094
a.C. filter capacitor voltage v required for determining control parametersCaAc filter capacitor current iCaThe equations (5) and (6) can be obtained by circuit principles:
Figure BDA0001813664820000095
Figure BDA0001813664820000096
and define vDaFor a-phase disturbance voltage (v)DbFor b-phase disturbance voltage, vDcIs a c-phase disturbance voltage) and is connected with the a-phase AC filter capacitor voltage vCa(b AC filter capacitor voltage vCbC AC filter capacitor voltage vCc) And a-phase filter inductance voltage vLfa(b-phase filter inductance voltage vLfbC-phase filter inductance voltage vLfc) To a
Figure BDA0001813664820000097
As shown in equation (7):
Figure BDA0001813664820000098
in addition, assume that during the sampling period T, the a-phase disturbance voltage vDaVariation approximating a AC filter capacitor voltage vCaThe variation, namely shown in equation (8):
Figure BDA0001813664820000101
adjusting the variables of equations (3) and (4) to a.C. filter capacitor voltage vCaAc filter capacitor current iCaAnd a phase disturbance voltage vDaThe state equation is shown in formula (9) and formula (10):
Figure BDA0001813664820000102
Figure BDA0001813664820000103
Figure BDA0001813664820000104
c ═ 100, formula (10)
Converting the continuous form of equation (9) and equation (10) into a discrete form, obtaining equation (11) and equation (12) as a discrete system analysis state equation:
x(k+1)＝Adx(k)+Bdu(k)，Ad＝eAT，
Figure BDA0001813664820000105
y(k)＝Cdx (k), equation (12)
By using the parameter of the sampling time k, the sampling time k +1 is obtainedThe parameter relations, x (k), x (k +1) are discrete values (digital detection values), u (k) is the system modulation factor. And the coefficient matrix A is obtained by Laplace transform methodd、BdAnd Cd. Finally, the coefficient matrix A is processedd、BdAnd CdSubstituting the formula (11) and the formula (12), and obtaining the formula (13) and the formula (14) after rearrangement:
Figure BDA0001813664820000106
Figure BDA0001813664820000111
Figure BDA0001813664820000112
Cdas (100), formula (14)
The parameters of equations (13) and (14) are defined as follows: actual value v of a-phase filter capacitor voltage at current sampling timeCa(k) (ii) a Actual value v of a-phase filter capacitor voltage at next sampling timeCa(k + 1); actual value i of a-phase filter capacitor current at current sampling timeCa(k) (ii) a Actual value i of a-phase filter capacitor current at next sampling timeCa(k + 1); a-phase disturbance electric voltage interval value v of current sampling timeDa(k) (ii) a Actual value v of a-phase disturbance voltage at next sampling timeDa(k + 1); filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a A sampling period T; DC link voltage Ed(ii) a a phase modulation factor ua(k) In that respect Therefore, the above equation is converted from the continuous equation, equation (9) and equation (10), into the discrete equation, such as equation (13) and equation (14). And coefficient matrix A can be derivedd、BdAnd CdRespectively as follows:
Figure BDA0001813664820000113
Cd＝(1 0 0)
the equations (13) and (14) are organized into another discrete state observer equation, such as equation (15):
Figure BDA0001813664820000114
the gain matrix K is obtained by finite time stability Control Law (deadbead Control Law), and the calculation result is shown as formula (16):
Figure BDA0001813664820000115
the parameters inside the gain matrix K are defined as follows: filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a The sampling period T. Finally, the obtained coefficient matrix Ad、BdAnd CdAnd the gain matrix K is substituted into the formula (15) to obtain the a-phase state observer equation as the formula (17).
Figure BDA0001813664820000121
The parameters of equation (17) are defined as follows: a-phase filter capacitor voltage state variable of current sampling time
Figure BDA0001813664820000122
A-phase filter capacitor voltage state variable of next sampling time
Figure BDA0001813664820000123
A-phase filter capacitor current state variable at current sampling time
Figure BDA0001813664820000124
Next samplingTime a-phase filter capacitor current state variable
Figure BDA0001813664820000125
A-phase disturbance voltage state variable of current sampling time
Figure BDA0001813664820000126
A-phase disturbance voltage state variable of next sampling time
Figure BDA0001813664820000127
The state variable is an operation value of the state observer, and the state variable at the next sampling time can be regarded as a predicted value. Wherein, the actual value v of the a-phase filter capacitor voltage at the current sampling timeCa(k) Is the actual measured quantity; DC link voltage EdIs the actual measured quantity. The following are known quantities: a phase modulation factor ua(k) (ii) a Filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a A sampling period T; gain element K1、K2、K3The actual voltage value v of the gain matrix K gain a phase filter capacitorCa(k)。
By analogy, a b-phase state observer equation can be obtained, as in equation (18):
Figure BDA0001813664820000128
the parameters of equation (18) are defined as follows: b-phase filter capacitor voltage state variable of current sampling time
Figure BDA0001813664820000129
B-phase filter capacitor voltage state variable of next sampling time
Figure BDA00018136648200001210
B-phase filter capacitor current state variable of current sampling time
Figure BDA0001813664820000131
B filter capacitor current state variable of next sampling time
Figure BDA0001813664820000132
B-phase disturbance voltage state variable of current sampling time
Figure BDA0001813664820000133
B-phase disturbance voltage state variable of next sampling time
Figure BDA0001813664820000134
Actual value v of voltage of b-phase filter capacitor at current sampling timeCb(k) (ii) a A sampling period T; DC link voltage Ed(ii) a b phase modulation factor ub(k) (ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a Gain element K1、K2、K3(ii) a Filter angular frequency omegaf。
By analogy, a c-phase state observer equation can be obtained, as in equation (19):
Figure BDA0001813664820000135
the parameters of equation (19) are defined as follows: c-phase filter capacitor voltage state variable of current sampling time
Figure BDA0001813664820000136
C-phase filter capacitor voltage state variable of next sampling time
Figure BDA0001813664820000137
C-phase filter capacitor current state variable of current sampling time
Figure BDA0001813664820000138
C phase of next sampling timeCurrent state variable of filter capacitor
Figure BDA0001813664820000139
C-phase disturbance voltage state variable of current sampling time
Figure BDA00018136648200001310
C-phase disturbance voltage state variable of next sampling time
Figure BDA00018136648200001311
Actual value v of c-phase filter capacitor voltage at current sampling timeCc(k) (ii) a A sampling period T; DC link voltage Ed(ii) a c phase modulation factor uc(k) (ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a Gain element K1、K2、K3(ii) a Filter angular frequency omegaf。
FIG. 2 illustrates a state observer control block 20, according to some embodiments. Equations (16) to (19) are equivalent to the state observer control block 20. Equations (11) - (12) are equivalent to the control block 21, the control block 21 is a discrete system analysis state equation, the control block 21 is an overall system representing the three-phase DC/AC converter 100, and the system modulation factor u (k) is input and multiplied by BdA coefficient matrix block 26. The discrete value x (k +1) of the next sampling time is restored to the discrete value x (k) of the previous sampling time, and the discrete value x (k) is multiplied by AdAfter the coefficient matrix block 27, the result is fed to the adder 22 where the discrete value x (k) is also multiplied by CdAfter the coefficient matrix block 28, the actual value v of the filter capacitor voltage is outputC(k)。
The actual value v of the filter capacitor voltage is captured by the state observer control block 20C(k) And system modulation factor u (k), actual value v of filter capacitor voltageC(k) Entering a subtracter 23 to filter the actual value v of the capacitor voltageC(k) Multiplying by a K gain matrix block 29, the K gain matrix block 29 gaining the actual value v of the filter capacitor voltageC(k) And then to the adder 24. Multiplication of the systematic modulation factor u (k) byCoefficient matrix BdInto adder 24. State variable of next sampling time
Figure BDA0001813664820000141
Through Z-1Block 25, reverting to the state variable of the last sampling time
Figure BDA0001813664820000142
Variable of state
Figure BDA0001813664820000143
After multiplying by the Ad coefficient matrix block 27, the result is fed to the adder 24, where the state variable is obtained
Figure BDA0001813664820000144
Also multiplied by Cd Coefficient matrix block 28, and obtains the filter capacitor voltage state variable at the current sampling time
Figure BDA0001813664820000145
Filter capacitor voltage state variable
Figure BDA0001813664820000146
Enters the subtractor 23. And the state observer control block 20 outputs the state variable for the next sampling time
Figure BDA0001813664820000147
In one embodiment, the state variable at the next sampling time
Figure BDA0001813664820000148
Equivalent voltage state variables of the a-phase filter capacitor
Figure BDA0001813664820000149
b-phase filter capacitor voltage state variable
Figure BDA00018136648200001410
c-phase filter capacitor voltage state variable
Figure BDA00018136648200001411
a-phase filter capacitor current state variable
Figure BDA00018136648200001412
b-phase filter capacitor current state variable
Figure BDA00018136648200001413
c-phase filter capacitor current state variable
Figure BDA00018136648200001414
a phase disturbance voltage state variable
Figure BDA00018136648200001415
b-phase disturbance voltage state variable
Figure BDA00018136648200001416
c-phase disturbance voltage state variable
Figure BDA00018136648200001417
Fig. 3 is a control flow diagram illustrating an off-grid mode according to some embodiments. The formula (17) of the above-mentioned a-phase observer equation, the formula (18) of the b-phase observer equation, and the formula (19) of the c-phase observer equation are programmed (program) into a chip having an arithmetic capability, for example: a Central Processing Unit (CPU), a Microcontroller Unit (MCU), a Field Programmable Gate Array (FPGA), etc., but not limited thereto. Therefore, the State Observer (State Observer)31 includes the formula (17), the formula (18), and the formula (19).
In one embodiment, the state observer 31 for a filter capacitor current sensorless control apparatus of the three-phase dc-ac converter 100 includes: a chip, the chip includes a state observer 31, the state observer 31 is used to capture a dc link voltage E of the three-phase dc-ac converter 100 at the current sampling timedActual voltage value v of phase-a filter capacitorCa(k) B phase filter capacitor voltage actual value vCb(k) C phase filter capacitorActual value v of pressureCc(k) The state observer 31 is used to output a filter capacitor current state variable at the next sampling time, where the filter capacitor current state variable is an average current value without ripple and is a current prediction value.
In one embodiment, the filter capacitor current state variables include a-phase filter capacitor current state variables
Figure BDA00018136648200001418
b-phase filter capacitor current state variable
Figure BDA00018136648200001419
And c-phase filter capacitor current state variables
Figure BDA0001813664820000151
The phases a, b and c can also be represented by the first phase, the second phase and the third phase. The filter capacitor current state variables enter the subtractor 33.
In one embodiment, the state observer 31 is used to output the voltage state variable of the a-phase filter capacitor at the next sampling time
Figure BDA0001813664820000152
b-phase filter capacitor voltage state variable
Figure BDA0001813664820000153
And c-phase filter capacitor voltage state variables
Figure BDA0001813664820000154
The filter capacitor voltage state variables are predicted values of the voltage at the next sampling time. The filter capacitor voltage state variables enter the subtractor 32.
In one embodiment, the state observer 31 is used to output the a-phase disturbance voltage state variable of the next sampling time
Figure BDA0001813664820000155
b-phase disturbance voltage state variable
Figure BDA0001813664820000156
And c-phase disturbance voltage state variable
Figure BDA0001813664820000157
The disturbance voltage state variables are predicted voltage values of the next sampling time. The disturbance voltage state variables enter the divider 35.
In one embodiment, the state observer 31 includes equation (17) of the a-phase state observer equation. In one embodiment, the state observer 31 includes equation (18) of the b-phase state observer equation. In one embodiment, the state observer 31 includes equation (19) of the c-phase state observer equation. In one embodiment, the state observer 31 contains equation (16) of the gain matrix K.
In one embodiment, the filter capacitor voltage is referenced to a command value vC *And a phase filter capacitor voltage state variable
Figure BDA0001813664820000158
b-phase filter capacitor voltage state variable
Figure BDA0001813664820000159
c-phase filter capacitor voltage state variable
Figure BDA00018136648200001510
After being compared with each other by the subtracter 32, the current reference command value i of the filter capacitor is obtained through the voltage controller AVRC *. The filter capacitor current is referred to a command value iC *And a phase filter capacitor current state variable
Figure BDA00018136648200001511
b-phase filter capacitor current state variable
Figure BDA00018136648200001512
c-phase filter capacitor current state variable
Figure BDA00018136648200001513
After being compared with each other by the subtracter 33, the voltage control value v is obtained through the current controller ACRcontrol *. In the adder 34, the voltage control value vcontrol *Feedforward voltage state variable plus next sample time
Figure BDA00018136648200001514
Obtaining the pulse width modulation comparison value vpwm_cmdWherein in the divider 35, the voltage state variable is fed forward
Figure BDA00018136648200001515
For a-phase disturbance voltage state variable
Figure BDA00018136648200001516
b-phase disturbance voltage state variable
Figure BDA00018136648200001517
c-phase disturbance voltage state variable
Figure BDA00018136648200001518
Divided by the DC link voltage Ed. Modulating the comparison value v according to the pulse widthpwm_cmdThen, a subsequent Pulse Width Modulation (PWM) is performed.
In one embodiment, referring back to the voltage and current parameters of the three-phase DC-AC converter 100 of FIG. 1, the process of deriving the ab line, bc line, and ca line state observer equations is as follows. The ab-line state observer equation is derived, and the ab-line elements are obtained from the a-phase and b-phase elements, which are expressed by the following equations (20) to (24).
Figure BDA0001813664820000161
vCab＝vCa-vCbEquation (21)
iIab＝iIa-iIbEquation (22)
iLab＝iLa-iLbEquation (23)
iCab＝iCa-iCbEquation (24)
The parameters of formula (20) to formula (24) are defined as follows: a alternating voltage vIa(ii) a b ac voltage vIb(ii) a ab line ac voltage vIab(ii) a a phase modulation factor ua(ii) a b phase modulation factor ub(ii) a ab line modulation factor uab(ii) a DC link voltage Ed(ii) a a AC filter capacitor voltage vCa(ii) a b AC filter capacitor voltage vCb(ii) a ab line ac filter capacitor voltage vCab(ii) a a alternating current iIa(ii) a b alternating current iIb(ii) a ab line alternating current iIab(ii) a a phase load current iLa(ii) a b-phase load current iLb(ii) a ab line load current iLab(ii) a a AC filter capacitor current iCa(ii) a b AC filter capacitor current iCb(ii) a ab line ac filter capacitance current iCab。
The ab-line AC voltage v of the three-phase DC-AC converter 100 can be respectively obtained according to the circuit principleIabAc current i to the inductor voltage ab lineIabThe relationship with the capacitance current is shown in equation (25) and equation (26), respectively:
Figure BDA0001813664820000162
Figure BDA0001813664820000163
the parameters are defined as follows: filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a ab line filter inductance voltage relation
Figure BDA0001813664820000164
ab line filter capacitance current relation
Figure BDA0001813664820000165
Equation (25) and equation (26) are expressed as state equations, as shown in equation (27) and equation (28):
Figure BDA0001813664820000166
Figure BDA0001813664820000167
ab line ac filter capacitor voltage v required for determining control parametersCabAc filter capacitor current i with ab lineCabThe equations (1) and (30) can be obtained by circuit principles as shown in the following equations:
Figure BDA0001813664820000171
Figure BDA0001813664820000172
and define vDabDisturbing the voltage for line ab and alternating the filtered capacitor voltage v with line abCabAnd ab line ac filter inductor voltage, as shown in equation (31);
Figure BDA0001813664820000173
in addition, suppose that the ab-line disturbance voltage variation is similar to the ab-line AC filter capacitor voltage v in the sampling period TCabThe variation is shown in equation (32).
Figure BDA0001813664820000174
The variables of formula (27) and formula (28)The adjustment is as follows: ac filter capacitor voltage v by ab lineCabAb line ac filter capacitance current iCabAnd ab line disturbance voltage vDabThe equation of state for the spindle is shown in equation (33) and equation (34):
Figure BDA0001813664820000175
Figure BDA0001813664820000176
c ═ 100, formula (34)
Converting the continuous form of equation (33) and equation (34) into a discrete form, and obtaining equations (35) and (36) as a discrete equation of state for system analysis:
Figure BDA0001813664820000177
y(k)＝Cdx(k)＝vCab(k) equation (36)
By using the parameter of the sampling time k, the parameter relation of the sampling time k +1 is obtained, wherein x (k), x (k +1) are discrete values (digital detection values), u (k) is a uniform modulation factor, and the sampling period T is obtained. And the coefficient matrix A is obtained by Laplace transform methodd、BdAnd Cd. Finally, the coefficient matrix A is processedd、BdAnd CdSubstituting into formula (35) and formula (36), and rearranging to obtain formula (37) and formula (38):
Figure BDA0001813664820000181
Figure BDA0001813664820000182
Cdas (100), formula (38)
The parameters of equation (37) and equation (38) are defined as follows: ab line filter capacitor voltage actual value v of current sampling timeCab(k) (ii) a Ab line filter capacitor voltage actual value v of next sampling timeCab(k + 1); actual value i of ab line filter capacitor current at current sampling timeCab(k) (ii) a Ab line filter capacitor current actual value i at next sampling timeCab(k + 1); actual value v of ab-line disturbance voltage at current sampling timeDab(k) (ii) a Ab line disturbance voltage actual value v of next sampling timeDab(k + 1); filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a A sampling period T; DC link voltage Ed(ii) a ab line modulation factor uab(k) In that respect Therefore, the above equation converts the continuous equation, equation (33) and equation (34), into discrete equation, such as equation (37) and equation (38). And coefficient matrix A can be derivedd、BdAnd CdRespectively as follows:
Figure BDA0001813664820000183
Cd＝(1 0 0)
the equations (37) and (38) are then compiled into another discrete state observer equation, such as equation (39):
Figure BDA0001813664820000184
the gain matrix K is obtained by finite time stability Control Law (deadbead Control Law), and the calculation result is shown as formula (40):
Figure BDA0001813664820000191
the parameters inside the gain matrix K are defined as follows: filter angular frequency omegaf(ii) a Filter inductor Lf (L)f＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a Week of samplingAnd a period T. Finally, the obtained coefficient matrix Ad、BdAnd CdAnd substituting the gain matrix K into equation (39) to obtain an ab line state observer equation, as in equation (41):
Figure BDA0001813664820000192
Figure BDA0001813664820000193
the ab-line filter capacitor voltage state variable at the current sampling time;
Figure BDA0001813664820000194
ab line filter capacitor voltage state variable at the next sampling time;
Figure BDA0001813664820000195
ab line filter capacitor current state variables at the current sampling time;
Figure BDA0001813664820000196
ab-line filter capacitor current state variables for the next sampling time;
Figure BDA0001813664820000197
the ab line disturbance voltage state variable at the current sampling time is obtained;
Figure BDA0001813664820000198
ab line disturbance voltage state variable at the next sampling time; v. ofCab(k) The actual value of the ab line filter capacitor voltage at the current sampling time is obtained; t is a sampling period; edIs a dc link voltage; u. ofab(k) Ab line modulation factor; l isfIs a filter inductor (L)f＝Lfa＝Lfb＝Lfc)；CfIs a filter capacitor (C)f＝Cfa＝Cfb＝Cfc)；K1、K2、K3For gain elements, the gain matrix K gain ab line filter capacitance voltageValue v of the lineCab(k)；ωfIs a filtered angular frequency.
By analogy, the magnitude of the b-phase element and the magnitude of the c-phase element are converted into the magnitude of the bc line element in a manner similar to the above equations (20) to (24), and the bc line state observer equation can be obtained through the derivation, as shown in equation (42):
Figure BDA0001813664820000201
Figure BDA0001813664820000202
the state variable of the bc line filter capacitor voltage at the current sampling time;
Figure BDA0001813664820000203
the bc line filter capacitor voltage state variable at the next sampling time;
Figure BDA0001813664820000204
the bc line filter capacitor current state variable at the current sampling time;
Figure BDA0001813664820000205
the bc line filter capacitor current state variable at the next sampling time;
Figure BDA0001813664820000206
the state variable of the bc line disturbance voltage at the current sampling time is obtained;
Figure BDA0001813664820000207
the bc line disturbance voltage state variable at the next sampling time; v. ofCbc(k) The actual value of the bc line filter capacitor voltage at the current sampling time is obtained; t is a sampling period; edIs a dc link voltage; u. ofbc(k) Is a bc line modulation factor; l isfIs a filter inductor (L)f＝Lfa＝Lfb＝Lfc)；CfIs a filter capacitor (C)f＝Cfa＝Cfb＝Cfc)；K1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
By analogy, the magnitude of the c-phase element and the magnitude of the a-phase element are converted into the magnitude of the ca line element in a manner similar to the above equations (20) to (24), and the ca line state observer equation can be obtained by the derivation, as shown in equation (43):
Figure BDA0001813664820000208
Figure BDA0001813664820000209
the voltage state variable of the ca line filter capacitor at the current sampling time;
Figure BDA00018136648200002010
the voltage state variable of the ca line filter capacitor at the next sampling time;
Figure BDA00018136648200002011
the current state variable of the ca line filter capacitor at the current sampling time;
Figure BDA00018136648200002012
the current state variable of the ca line filter capacitor at the next sampling time;
Figure BDA00018136648200002013
the state variable of the ca line disturbance voltage at the current sampling time is obtained;
Figure BDA00018136648200002014
the ca line disturbance voltage state variable at the next sampling time; v. ofCca(k) The actual value of the voltage of the ca line filter capacitor at the current sampling time is obtained; t is a sampling period; edIs a dc link voltage; u. ofca(k) Is a ca line modulation factor; l isfIs a filter inductor; cfIs a filter capacitor (C)f＝Cfa＝Cfb＝Cfc)；K1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
Referring to fig. 2 again, the formula (41), the formula (42), or the formula (43) is equivalent to the state observer control block 20, and the control flow thereof is similar to the description of fig. 2and is not repeated. In one embodiment, the state variable at the next sampling time
Figure BDA0001813664820000211
The voltage state variable of the ab line filter capacitor can be equalized
Figure BDA0001813664820000212
bc line filter capacitor voltage state variable
Figure BDA0001813664820000213
ca line filter capacitor voltage state variable
Figure BDA0001813664820000214
ab line filter capacitance current state variable
Figure BDA0001813664820000215
bc line filter capacitor current state variable
Figure BDA0001813664820000216
ca line filter capacitor current state variable
Figure BDA0001813664820000217
ab line disturbance voltage state variable
Figure BDA0001813664820000218
bc line disturbance voltage state variable
Figure BDA0001813664820000219
ca line disturbance voltage state variable
Figure BDA00018136648200002110
Fig. 4 is a control-flow diagram that illustrates an off-grid mode in accordance with some embodiments. The formula (41) of the ab line state observer equation, the formula (42) of the bc line state observer equation, and the formula (43) of the ca line state observer equation are programmed (program) into a chip having an arithmetic capability, for example: a Central Processing Unit (CPU), a Microcontroller Unit (MCU), a Field Programmable Gate Array (FPGA), etc., but not limited thereto. Therefore, the state observer 41 includes the formula (41), the formula (42), and the formula (43).
In one embodiment, the filter capacitor current sensorless control apparatus for the three-phase dc-ac converter 100 with the state observer 41 comprises: a chip, which includes a state observer 41, the state observer 41 is used to capture a dc link voltage E of the three-phase dc-ac converter 100 at the current sampling timedAb line filter capacitor voltage actual value vCab(k) Bc line filter capacitor voltage actual value vCbc(k) And the actual value v of the filter capacitor voltage of the ca lineCca(k) The state observer 41 is used to output a filter capacitor current state variable at the next sampling time, where the filter capacitor current state variable is an average current value without ripple and is a current prediction value. ab line filter capacitor voltage actual value vCab(k) Bc line filter capacitor voltage actual value vCbc(k) And the actual value v of the filter capacitor voltage of the ca lineCca(k) Is the actual value v of the a-phase filter capacitor voltageCa(k) B phase filter capacitor voltage actual value vCb(k) C-phase filter capacitor voltage actual value vCc(k) Is converted into.
In one embodiment, the filter capacitor current state variables include ab-line filter capacitor current state variables
Figure BDA00018136648200002111
bc line filter capacitor current state variable
Figure BDA00018136648200002112
ca line filterCapacity current state variable
Figure BDA00018136648200002113
The ab line, bc line, ca line may be replaced with the first line, the second line, and the third line. The filter capacitor current state variables enter the subtractor 43.
In one embodiment, the state observer 41 is used to output the ab-line filter capacitor voltage state variable at the next sampling time
Figure BDA0001813664820000221
bc line filter capacitor voltage state variable
Figure BDA0001813664820000222
ca line filter capacitor voltage state variable
Figure BDA0001813664820000223
The filter capacitor voltage state variables are predicted values of the voltage at the next sampling time. The filter capacitor voltage state variables enter the subtractor 42.
In one embodiment, the state observer 41 is used to output the ab-line disturbance voltage state variable at the next sampling time
Figure BDA0001813664820000224
bc line disturbance voltage state variable
Figure BDA0001813664820000225
ca line disturbance voltage state variable
Figure BDA0001813664820000226
The disturbance voltage state variables are predicted voltage values of the next sampling time. The disturbance voltage state variables enter the divider 46.
In one embodiment, the state observer 41 includes the formula (41) of the ab-line state observer equation. In one embodiment, the state observer 41 contains the formula (42) of the bc line state observer equation. In one embodiment, the state observer 41 contains the formula (43) of the ca line state observer equation. In one embodiment, the state observer 41 includes the formula (40) of the gain matrix K.
In one embodiment, referring to FIG. 4, the filter capacitor voltage is referenced to a command value vC *And ab line filter capacitor voltage state variable
Figure BDA0001813664820000227
bc line filter capacitor voltage state variable
Figure BDA0001813664820000228
ca line filter capacitor voltage state variable
Figure BDA0001813664820000229
After being compared with each other by the subtracter 42, the current reference command value i of the filter capacitor is obtained through the voltage controller AVRC *. The filter capacitor current is referred to a command value iC *And ab line filter capacitor current state variable
Figure BDA00018136648200002210
bc line filter capacitor current state variable
Figure BDA00018136648200002211
ca line filter capacitor current state variable
Figure BDA00018136648200002212
After being compared with each other by the subtracter 43, the voltage control value v is obtained through the current controller ACRcontrol *. In the adder 45, the voltage control value vcontrol *Feedforward voltage state variable plus next sample time
Figure BDA00018136648200002213
Obtaining the pulse width modulation comparison value vpwm_cmdWherein in the divider 46, the voltage state variable is fed forward
Figure BDA00018136648200002214
Perturbing voltage state changes for ab linesMeasurement of
Figure BDA00018136648200002215
bc line disturbance voltage state variable
Figure BDA00018136648200002216
ca line disturbance voltage state variable
Figure BDA00018136648200002217
Divided by the dc link voltage Ed. Modulating the comparison value v according to the pulse widthpwm_cmdThen, a subsequent Pulse Width Modulation (PWM) is performed.
In one embodiment, referring back to the voltage and current parameters of fig. 1, the following is a process for deriving D-axis (direct axis) and Q-axis (quadrature axis) state observer equations. The D-axis element and the Q-axis element are obtained by Park's Transformation (Park's Transformation) of the phase a element, the phase b element, and the phase c element of the three-phase dc-ac converter 100. The park transformation projects the a, b, c phase current or voltage magnitude of the stator to the direct axis (D axis), quadrature axis (Q axis) and zero axis (0 axis) perpendicular to the DQ plane as the rotor rotates, as in equation (44):
Figure BDA0001813664820000231
the relationship between the D-axis and Q-axis ac voltages, the ac currents, the inductor voltages, and the capacitor currents of the three-phase dc-ac converter 100 can be obtained according to the circuit principle, as shown in equation (45) and equation (46):
Figure BDA0001813664820000232
Figure BDA0001813664820000233
the parameters are defined as: d-axis alternating current iId(ii) a Q-axis alternating current iIq(ii) a D-axis alternating voltage vId(ii) a Q-axis alternating voltage vIq(ii) a D-axis AC filter capacitor voltage vCd(ii) a Q-axis AC filter capacitor voltage vCq(ii) a D-axis alternating current filter capacitor current iCd(ii) a Q-axis AC filter capacitor current iCq(ii) a Filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc)。
Equation (45) and equation (46) are expressed as equation (47) and equation (48):
Figure BDA0001813664820000234
Figure BDA0001813664820000235
to obtain the relation between the ac filter capacitor voltage and the ac filter capacitor current required by the control parameter, the equations can be obtained by circuit principles as shown in equations (49), (50), (51) and (52):
Figure BDA0001813664820000236
Figure BDA0001813664820000237
Figure BDA0001813664820000238
Figure BDA0001813664820000241
the parameters are defined as: introducing another parameter, D-axis AC filter capacitor current iCdx(ii) a Q-axis AC filter capacitor current iCqx(ii) a D-axis disturbance voltage vDd(ii) a Q-axis disturbance voltage vDq(ii) a D-axis load current iLd(ii) a Q-axis load current iLq(ii) a Another D-axis disturbance voltage vDdx(ii) a Another Q-axis disturbance voltage vDqx(ii) a D-axis modulation factor ud(ii) a Q-axis modulation factor uq。
In addition, it is assumed that the disturbance voltage variation is similar to the capacitor voltage variation in the sampling period T, which is shown in equation (53):
Figure BDA0001813664820000242
the variables of equations (49), (50), (51) and (52) are adjusted to: AC filter capacitor voltage v with D axisCdD-axis ac filter capacitor current iCdxAnd D-axis disturbance voltage vDdxThe equation of state for the spindle is shown in equations (54) and (55):
Figure BDA0001813664820000243
Figure BDA0001813664820000244
c is (100), formula (55).
Converting the continuous form of equations (54) and (55) into a discrete form of equations (56) and (57) as discrete system analysis state equations:
Figure BDA0001813664820000245
y(k)＝Cdx (k), equation (57)
By using the parameter of the sampling time k, the parameter relation of the sampling time k +1 is obtained, wherein x (k), x (k +1) are discrete values (digital detection values), u (k) is a uniform modulation factor, and the sampling period T is obtained. And the coefficient matrix A is obtained by Laplace transform methodd、BdAnd Cd. Finally, the coefficient matrix A is processedd、BdAnd CdSubstituting into formula (56) and formula (57), and rearranging to obtain formula (58) and formula (59):
Figure BDA0001813664820000251
Figure BDA0001813664820000252
Cdas (100), formula (59)
The parameters of equations (58) and (59) are defined as follows: d-axis filter capacitor voltage actual value v at current sampling timeCd(k) (ii) a D-axis filter capacitor voltage actual value v at next sampling timeCd(k + 1); d-axis filter capacitor current actual value i at current sampling timeCdx(k) (ii) a D-axis filter capacitor current actual value i at next sampling timeCd(k + 1); d-axis disturbance voltage actual value v of current sampling timeDd(k) (ii) a D-axis disturbance voltage actual value v of next sampling timeDd(k + 1); filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a A sampling period T; DC link voltage Ed(ii) a D-axis modulation factor ud(k) In that respect Thus, the equations of the continuous type, equations (54) and (55) are transformed into discrete state equations, such as equations (58) and (59). And coefficient matrix A can be derivedd、BdAnd CdRespectively as follows:
Figure BDA0001813664820000253
Cd＝(1 0 0)
the equations (58) and (59) are then compiled into another discrete state observer equation, such as equation (60):
Figure BDA0001813664820000254
the gain matrix K is obtained by finite time stability Control (Deadbed Control Law), and the calculation result is shown as formula (61):
Figure BDA0001813664820000261
the parameters inside the gain matrix K are defined as: filter angular frequency omegaf(ii) a Filter inductance Lf(Lf＝Lfa＝Lfb＝Lfc) (ii) a Filter capacitor Cf(Cf＝Cfa＝Cfb＝Cfc) (ii) a The sampling period T. Finally, the obtained coefficient matrix Ad、BdAnd CdAnd substituting the gain matrix K into equation (60) to obtain the D-axis state observer equation, as shown in equation (62):
Figure BDA0001813664820000262
Figure BDA0001813664820000263
the voltage state variable of the D-axis filter capacitor at the current sampling time is obtained;
Figure BDA0001813664820000264
the voltage state variable of the D-axis filter capacitor at the next sampling time;
Figure BDA0001813664820000265
the current state variable of the D-axis filter capacitor at the current sampling time is obtained;
Figure BDA0001813664820000266
the current state variable of the D-axis filter capacitor at the next sampling time;
Figure BDA0001813664820000267
the D-axis disturbance voltage state variable is the current sampling time;
Figure BDA0001813664820000268
a D-axis disturbance voltage state variable at the next sampling time; v. ofCd(k) The actual value of the D-axis filter capacitor voltage at the current sampling time is obtained; t is a sampling period; edIs a dc link voltage; u. ofd(k) Is a D-axis modulation factor; l isfIs a filter inductor (L)f＝Lfa＝Lfb＝Lfc)；CfIs a filter capacitor (C)f＝Cfa＝Cfb＝Cfc)；K1、K2、K3As gain elements, the gain matrix K gains the actual value v of the D-axis filter capacitor voltageCd(k)；ωfIs the filtered angular frequency.
By analogy, a Q-axis state observer equation can be obtained, as in equation (63):
Figure BDA0001813664820000271
Figure BDA0001813664820000272
the voltage state variable of the Q-axis filter capacitor at the current sampling time is obtained;
Figure BDA0001813664820000273
the Q-axis filter capacitor voltage state variable at the next sampling time;
Figure BDA0001813664820000274
the current state variable of the Q-axis filter capacitor at the current sampling time is obtained;
Figure BDA0001813664820000275
the current state variable of the Q-axis filter capacitor at the next sampling time;
Figure BDA0001813664820000276
a Q-axis disturbance voltage state variable of the current sampling time;
Figure BDA0001813664820000277
the Q-axis disturbance voltage state variable at the next sampling time; v. ofCq(k) The actual value of the voltage of the Q-axis filter capacitor at the current sampling time is obtained; t is a sampling period; edIs a dc link voltage; u. ofq(k) Is a Q-axis modulation factor; l isfIs a filter inductor (L)f＝Lfa＝Lfb＝Lfc)；CfIs a filter capacitor (C)f＝Cfa＝Cfb＝Cfc)；K1、K2、K3Is a gain element; omegafIs the filtered angular frequency.
Referring to fig. 2 again, the formula (62) or the formula (63) is equivalent to the state observer control block 20, and the control flow thereof is similar to the description of fig. 2and will not be described again. In one embodiment, the state variable at the next sampling time
Figure BDA0001813664820000278
The voltage state variables of the D-axis filter capacitors can be equalized
Figure BDA0001813664820000279
D-axis filter capacitor current state variable
Figure BDA00018136648200002710
D-axis disturbance voltage state variable
Figure BDA00018136648200002711
Q-axis filter capacitor voltage state variable
Figure BDA00018136648200002712
Q-axis filter capacitor current state variable
Figure BDA00018136648200002713
Q-axis disturbance voltage state variable
Figure BDA00018136648200002714
Fig. 5 is a control flow diagram illustrating an off-grid mode according to some embodiments. The formula (62) of the D-axis state observer equation and the formula (63) of the Q-axis state observer equation are programmed (program) into a chip having an arithmetic capability, for example: a Central Processing Unit (CPU), a Microcontroller Unit (MCU), a Field Programmable Gate Array (FPGA), etc., but not limited thereto. Therefore, the state observer 51 includes the formula (62) and the formula (63).
In one embodiment, the filter capacitor current sensorless control apparatus for the three-phase dc-ac converter 100 using the state observer 51 includes: a chip, the chip includes a state observer 51, the state observer 51 is used to capture a dc link voltage E of the three-phase dc-ac converter 100 at the current sampling timedD-axis filter capacitor voltage actual value vCd(k) Q-axis filter capacitor voltage actual value vCq(k) The state observer 51 is used to output the filter capacitor current state variable at the next sampling time, which is an average current value without ripple and is a current prediction value. D-axis filter capacitor voltage actual value vCd(k) Q-axis filter capacitor voltage actual value vCq(k) Is the actual value v of the a-phase filter capacitor voltageCa(k) B phase filter capacitor voltage actual value vCb(k) C-phase filter capacitor voltage actual value vCc(k) Is converted into.
In one embodiment, the filter capacitor current state variables comprise Q-axis filter capacitor current state variables
Figure BDA0001813664820000281
And D-axis filter capacitor current state variables
Figure BDA0001813664820000282
The filter capacitor current state variables enter the subtractor 53.
In one embodiment, the state observer 51 is used to output the voltage state variable of the Q-axis filter capacitor at the next sampling time
Figure BDA0001813664820000283
And D-axis filter capacitor voltage state variables
Figure BDA0001813664820000284
The filter capacitor voltage state variables are predicted values of the voltage at the next sampling time. The filter capacitor voltage state variables enter the subtractor 52.
In one embodiment, the state observer 51 is used to output the Q-axis disturbance voltage state variable at the next sampling time
Figure BDA0001813664820000285
And D-axis disturbance voltage state variable
Figure BDA0001813664820000286
The disturbance voltage state variables are predicted voltage values of the next sampling time. The disturbance voltage state variables enter the divider 55.
In one embodiment, the state observer 51 includes the formula (62) of the D-axis state observer equation. In one embodiment, the state observer 51 includes the formula (63) of the D-axis state observer equation. In one embodiment, state observer 51 includes equation (61) of gain matrix K.
In one embodiment, referring to FIG. 5, the filter capacitor voltage is referenced to a command value vC *And Q-axis filter capacitor voltage state variable
Figure BDA0001813664820000287
And D-axis filter capacitor voltage state variables
Figure BDA0001813664820000288
After being compared with each other by the subtracter 52, the current reference command value i of the filter capacitor is obtained through the voltage controller AVRC *. The filter capacitor current is referred to a command value iC *And Q-axis filter capacitor current state variable
Figure BDA0001813664820000289
And D-axis filter capacitance current shapeVariable of state
Figure BDA00018136648200002810
After being compared with each other by the subtracter 53, the voltage control value v is obtained through the current controller ACRcontrol *. In the adder 54, the voltage control value vcontrol *Feedforward voltage state variable plus next sample time
Figure BDA00018136648200002811
Obtaining the pulse width modulation comparison value vpwm_cmdWherein in the divider 55, the voltage state variable is fed forward
Figure BDA00018136648200002812
Perturbing a voltage state variable for the Q-axis
Figure BDA00018136648200002813
And D-axis disturbance voltage state variable
Figure BDA00018136648200002814
Divided by the DC link voltage Ed. Modulating the comparison value v according to the pulse widthpwm_cmdThen, a subsequent Pulse Width Modulation (PWM) is performed.
FIG. 6 is a flow diagram illustrating a method of filtered capacitive current sensorless control using a state observer, according to some embodiments. A method of sensorless control of filter capacitor current for a three-phase dc-to-ac converter 100 by a state observer 31, 41, or 51, comprising: receiving a DC link voltage E of the three-phase DC-AC converter at the current sampling timed(step 61); receiving the actual voltage value v of the a-phase (first phase) filter capacitor of the three-phase DC-AC converter 100 at the current sampling timeCa(k) B-phase (second phase) filter capacitor voltage actual value vCb(k) C-phase (third phase) filter capacitor voltage actual value vCc(k) (step 62); and outputting a filter capacitor current state variable, which is a predicted value of the current at the next sampling time, by the state observer 31, 41, or 51The filter capacitor current state variable is an average current value without ripple (step 63).
In one embodiment, the filter capacitor C of the three-phase DC/AC converter 100 is obtained by the state observer 31, 41 or 51 according to the sampling period Tfa、Cfb、Cfc(Cf＝Cfa＝Cfb＝Cfc) And a filter inductor Lfa、Lfb、Lfc(Lf＝Lfa＝Lfb＝Lfc) Defining a gain matrix K, as shown in equation (16), the gain matrix K gains the actual value v of the a-phase filter capacitor voltageCa(k) B phase filter capacitor voltage actual value vCb(k) C-phase filter capacitor voltage actual value vCc(k)。
In one embodiment, referring to FIG. 3, the filter capacitor current state variables comprise a-phase filter capacitor current state variables
Figure BDA0001813664820000291
b-phase filter capacitor current state variable
Figure BDA0001813664820000292
And c-phase filter capacitor current state variables
Figure BDA0001813664820000293
The a, b, and c phases may also be referred to as a first phase, a second phase, and a third phase.
In one embodiment, referring to FIG. 3, the voltage state variable of the a-phase filter capacitor is output by the state observer 31
Figure BDA0001813664820000294
b-phase filter capacitor voltage state variable
Figure BDA0001813664820000295
And c-phase filter capacitor voltage state variables
Figure BDA0001813664820000296
When the voltage state variables of the filter capacitors are the next samplingThe predicted value of the voltage therebetween.
In one embodiment, referring to FIG. 3, a-phase disturbance voltage state variable is output by a state observer 31
Figure BDA0001813664820000297
b-phase disturbance voltage state variable
Figure BDA0001813664820000298
And c-phase disturbance voltage state variable
Figure BDA0001813664820000299
The disturbance voltage state variables are predicted voltage values of the next sampling time.
In one embodiment, referring to FIG. 4, the actual voltage v of the a-phase filter capacitor is converted by the state observer 41Ca(k) B phase filter capacitor voltage actual value vCb(k) And c-phase filter capacitor voltage actual value vCc(k) Respectively ab line filter capacitor voltage actual value vCab(k) Bc line filter capacitor voltage actual value vCbc(k) And the actual value v of the filter capacitor voltage of the ca lineCca(k)。
In one embodiment, referring to FIG. 4, the filter capacitor current state variables comprise ab-line filter capacitor current state variables
Figure BDA0001813664820000301
bc line filter capacitor current state variable
Figure BDA0001813664820000302
And ca line filter capacitor current state variables
Figure BDA0001813664820000303
In one embodiment, referring to FIG. 4, ab line filter capacitor voltage state variables are output by a state observer 41
Figure BDA0001813664820000304
bc line filter capacitor voltage state variable
Figure BDA0001813664820000305
And ca line filter capacitor voltage state variable
Figure BDA0001813664820000306
The voltage state variables of the filter capacitors are predicted values of the voltage at the next sampling time.
In one embodiment, referring to FIG. 4, the ab-line disturbance voltage state variable is output by the state observer 41
Figure BDA0001813664820000307
bc line disturbance voltage state variable
Figure BDA0001813664820000308
And ca line disturbance voltage state variable
Figure BDA0001813664820000309
The disturbance voltage state variables are predicted voltage values of the next sampling time.
In one embodiment, referring to FIG. 5, the actual voltage v of the a-phase filter capacitor is converted by the state observer 51Ca(k) B phase filter capacitor voltage actual value vCb(k) And c-phase filter capacitor voltage actual value vCc(k) Is the actual value v of the D-axis filter capacitor voltageCd(k) And the actual voltage value v of the Q-axis filter capacitorCq(k)。
In one embodiment, referring to FIG. 5, the filter capacitor current state variables comprise Q-axis (quadrature axis) filter capacitor current state variables
Figure BDA00018136648200003010
And D-axis (direct axis) filter capacitor current state variables
Figure BDA00018136648200003011
In one embodiment, referring to FIG. 5, the Q-axis filter capacitor voltage state variable is output by a state observer 51
Figure BDA00018136648200003012
And D-axis filter capacitor voltage state variables
Figure BDA00018136648200003013
The filter capacitor voltage state variables are predicted values of the voltage at the next sampling time.
In one embodiment, referring to FIG. 5, a Q-axis disturbance voltage state variable is output by the state observer 51
Figure BDA00018136648200003014
And D-axis disturbance voltage state variable
Figure BDA00018136648200003015
The disturbance voltage state variables are predicted voltage values of the next sampling time.
Fig. 7 is a waveform diagram illustrating ac filter capacitor voltages of a phase element state observer, according to some embodiments. In fig. 7, the horizontal axis of the graphs (a) and (b) represents time (sec), and the vertical axis represents voltage (volt). Fig. 7 (a) shows the simulation result of the state observer 31 for the phase element, and the state observer 31 includes formula (17), formula (18), and formula (19). Fig. 7 (b) is an enlarged view of a block portion of fig. (a).
In the graph (b) of fig. 7, the lower irregular slope lines represent the continuous ac filter capacitor voltage actual value 72, and the ac filter capacitor voltage actual value 72 represents the actual physical quantity. The ac filter capacitor voltage predicted value 71 with the sawtooth wave in a discrete state, the sawtooth wave formation due to sample and hold (sample and hold), and the ac filter capacitor voltage predicted value 71 being a state variable of the a, b, or c phase filter capacitor voltage output by the state observer 31
Figure BDA0001813664820000311
The predicted value 71 of the ac filter capacitor voltage is the predicted value of the voltage at the next sampling time, and the predicted value 71 of the ac filter capacitor voltage is close to the actual value 72 of the ac filter capacitor voltage, so that the accuracy of the predicted value can be verified.
Fig. 8 is a waveform diagram illustrating ac filter capacitor currents for a phase element state observer, according to some embodiments. In fig. 8, the horizontal axis of graphs (a) and (b) represents time (sec) and the vertical axis represents current (ampere). Fig. 8 (a) shows the simulation result of the state observer 31 for the phase element, and the state observer 31 includes formula (17), formula (18), and formula (19). Fig. 8 (b) is an enlarged view of a block portion of fig. (a).
In the graph (b) in fig. 8, ripple is a continuous ac filter capacitor current actual value 73, and the ac filter capacitor current actual value 73 is an actual physical quantity. The smoothed slope is the ac filter capacitor current predicted value 74, and the ac filter capacitor current predicted value 74 is the a-phase filter capacitor current state variable output by the state observer 31
Figure BDA0001813664820000312
b-phase filter capacitor current state variable
Figure BDA0001813664820000313
And c-phase filter capacitor current state variables
Figure BDA0001813664820000314
The state observer 31 includes equations (17), (18), and (19), and the ac filter capacitor current predicted value 74 is an average current value and has no ripple component, and is a current predicted value. The state observer 31 can predict the filter capacitor current without additional hardware circuitry or sensors, and the sensorless state observer 31 reduces the circuit cost. For the digital control system, the calculation results of the state observer 31 are all the predicted values of the next sampling time, so that the sampling error time can be reduced, and the overall system performance can be improved.
Fig. 9 is a waveform diagram illustrating ac filter capacitor voltages for a line element state observer, according to some embodiments. In fig. 9, the horizontal axis of the graphs (a) and (b) represents time (sec), and the vertical axis represents voltage (volt). Fig. 9 (a) shows the simulation result of the state observer 41 for the line element, and therefore the state observer 41 includes the formula (41), the formula (42), and the formula (43). Fig. 9 (b) is an enlarged view of a block portion of the diagram (a).
In the graph (b) of fig. 9, the lower irregular slope lines represent the continuous ac filter capacitor voltage actual values 76, and the ac filter capacitor voltage actual values 76 represent actual physical quantities. The ac filter capacitor voltage predicted value 75 with the sawtooth wave in a discrete state, the sawtooth wave formation due to sample and hold (sample and hold), and the ac filter capacitor voltage predicted value 75 being an ab-line filter capacitor voltage state variable output by the state observer 41
Figure BDA0001813664820000315
bc line filter capacitor voltage state variable
Figure BDA0001813664820000316
And ca line filter capacitor voltage state variable
Figure BDA0001813664820000321
The predicted ac filter capacitor voltage value 75 is the predicted voltage value at the next sampling time, and the predicted ac filter capacitor voltage value 75 is close to the actual ac filter capacitor voltage value 76, so the accuracy can be verified.
Fig. 10 is a waveform diagram illustrating ac filter capacitance current of a line element state observer, according to some embodiments. In fig. 10, the horizontal axis of graphs (a) and (b) represents time (sec) and the vertical axis represents current (ampere). Fig. 10 (a) shows the simulation result of the state observer 41 as a line element, and the state observer 41 includes formula (41), formula (42), and formula (43). Fig. 10 (b) is an enlarged view of a block portion of fig. (a).
In the graph (b) of fig. 10, ripple is a continuous ac filter capacitor current actual value 77, and the ac filter capacitor current actual value 77 is an actual physical quantity. The smoothed slope is the AC filter capacitor current predicted value 78, and the AC filter capacitor current predicted value 78 is the filter capacitor current state variable of ab line, bc line, and ca line output from the state observer 41
Figure BDA0001813664820000322
The state observer 41 includes equations (41), (42) and (43), so that the predicted AC filter capacitor current value 78 is the average currentThe current value is free of ripple component and is the predicted value of current. The line element state observer 41 predicts the filter capacitance current without additional hardware circuitry or sensors, and the sensorless state observer 41 reduces the circuit cost. For the digital control system, the calculation results of the state observer 41 are all the predicted values of the next sampling time, so that the sampling error time can be reduced, and the overall system performance can be improved.
FIG. 11 is a waveform diagram illustrating AC filter capacitor voltages for a D-Q axis elemental state observer, according to some embodiments. In fig. 11, the horizontal axis of the graphs (a) and (b) represents time (sec), and the vertical axis represents voltage (volt). Fig. 11 (a) shows the simulation result of the state observer 51 for the D-Q axis elements, and the state observer 51 includes equations (62) and (63). Fig. 11 (b) is an enlarged view of a block portion of fig. (a).
In the graph (b) of fig. 11, the lower irregular slope lines represent the actual ac filter capacitor voltage values 82, and the actual ac filter capacitor voltage values 82 represent actual physical quantities. The ac filter capacitor voltage prediction 81 with the sawtooth wave in a discrete state, the sawtooth wave due to sample and hold (saw and hold), the ac filter capacitor voltage prediction 81 being the Q-axis filter capacitor voltage state variable output by the state observer 51
Figure BDA0001813664820000323
And D-axis filter capacitor voltage state variables
Figure BDA0001813664820000324
The predicted value 81 of the AC filter capacitor voltage is the predicted value of the voltage at the next sampling time, and the predicted value 81 of the AC filter capacitor voltage is close to the actual value 82 of the AC filter capacitor voltage, so the accuracy can be verified.
Fig. 12 is a waveform diagram illustrating ac filter capacitance currents for a D-Q axis elemental state observer, according to some embodiments. In fig. 12, the horizontal axis of graphs (a) and (b) represents time (sec) and the vertical axis represents current (ampere). Fig. 12 (a) shows the simulation result of the state observer 51 as a D-Q axis element, and the state observer 51 includes equations (62) and (63). Fig. 12 (b) is an enlarged view of a block portion of fig. (a).
In the graph (b) in fig. 12, ripple is a continuous ac filter capacitor current actual value 83, and the ac filter capacitor current actual value 83 is an actual physical quantity. The smooth slope is the AC filter capacitor current prediction value 84, and the AC filter capacitor current prediction value 84 is the Q-axis filter capacitor current state variable output by the state observer 51
Figure BDA0001813664820000331
And D-axis filter capacitor current state variables
Figure BDA0001813664820000332
The state observer 51 includes equations (62) and (63), so that the ac filter capacitor current predicted value 84 is already the average current value and has no ripple component, and is the current predicted value. The state observer 51 of the D-Q axis element can predict the filter capacitance current without additional hardware circuits or sensors, and the sensorless state observer 51 allows circuit cost reduction. For the digital control system, the calculation results of the state observer 51 are all the predicted values of the next sampling time, so that the sampling error time can be reduced, and the overall system performance can be improved.
In summary, the present invention provides a sensorless filter capacitor current control method and apparatus for a three-phase dc-ac converter, and provides a sensorless state observer, which is suitable for controlling phase elements, line elements, and D-Q axis elements, and does not require an additional sensor or an external hardware detection circuit to detect the filter capacitor current, and can predict the filter capacitor voltage, the filter capacitor current, and the disturbance voltage at the next sampling time by the sensorless state observer by capturing the current filter capacitor voltage and the current dc link voltage. In particular, the value of the filter capacitor current at the next sampling time can be obtained without detecting the current filter capacitor current, and the predicted filter capacitor current is the average current value and has no ripple component. In addition, the control device and the method can reduce the error of sampling time and improve the performance of a control system. The sensorless state observer allows a reduction in the relative circuit costs. Moreover, the predicted value of the next sampling time is high in accuracy and predictive, and is filter capacitor current control, so that the system response is good.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims (28)

1. A sensorless control method of filter capacitor current for a three-phase DC-AC converter by a state observer comprises the following steps:
receiving a direct current link voltage of the three-phase direct current-alternating current converter at the current sampling time;
receiving a first phase filter capacitor voltage actual value, a second phase filter capacitor voltage actual value and a third phase filter capacitor voltage actual value of the three-phase DC-AC converter at the current sampling time; and
outputting a filter capacitor current state variable by a state observer, wherein the filter capacitor current state variable is a current predicted value of the next sampling time, and the filter capacitor current state variable is an average current value without ripple;
wherein the method further comprises at least one of:
converting the first phase filter capacitor voltage actual value, the second phase filter capacitor voltage actual value and the third phase filter capacitor voltage actual value into a first line filter capacitor voltage actual value, a second line filter capacitor voltage actual value and a third line filter capacitor voltage actual value respectively by the state observer;
converting the actual voltage values of the first phase filter capacitor, the second phase filter capacitor and the third phase filter capacitor into an actual voltage value of a Q-axis filter capacitor and an actual voltage value of a D-axis filter capacitor by the state observer.
2. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 1, further comprising:
and defining a gain matrix by the state observer according to a sampling period, a filter capacitor of the three-phase DC-AC converter and a filter inductor, wherein the gain matrix gains the actual voltage value of the first phase filter capacitor, the actual voltage value of the second phase filter capacitor and the actual voltage value of the third phase filter capacitor.
3. The method of claim 1, wherein the filter capacitor current state variables comprise a first phase filter capacitor current state variable, a second phase filter capacitor current state variable, and a third phase filter capacitor current state variable.
4. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 3, further comprising:
and outputting a first phase filter capacitor voltage state variable, a second phase filter capacitor voltage state variable and a third phase filter capacitor voltage state variable by the state observer, wherein the first phase filter capacitor voltage state variable, the second phase filter capacitor voltage state variable and the third phase filter capacitor voltage state variable are predicted values of the voltage of the next sampling time.
5. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 4, further comprising:
and outputting a first phase disturbance voltage state variable, a second phase disturbance voltage state variable and a third phase disturbance voltage state variable by the state observer, wherein the first phase disturbance voltage state variable, the second phase disturbance voltage state variable and the third phase disturbance voltage state variable are predicted values of the voltage of the next sampling time.
6. The sensorless filter capacitor current control method for a three-phase dc-to-ac converter of claim 1, wherein the filter capacitor current state variables comprise a first line filter capacitor current state variable, a second line filter capacitor current state variable, and a third line filter capacitor current state variable.
7. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 6, further comprising:
and outputting a first line filter capacitor voltage state variable, a second line filter capacitor voltage state variable and a third line filter capacitor voltage state variable by the state observer, wherein the filter capacitor voltage state variables are predicted voltage values of the next sampling time.
8. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 7 further comprising:
and outputting a first line disturbance voltage state variable, a second line disturbance voltage state variable and a third line disturbance voltage state variable by the state observer, wherein the first line disturbance voltage state variable, the second line disturbance voltage state variable and the third line disturbance voltage state variable are predicted values of the voltage of the next sampling time.
9. The method of claim 1, wherein the filter capacitor current state variables comprise a Q-axis filter capacitor current state variable and a D-axis filter capacitor current state variable.
10. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 9, further comprising:
and outputting a Q-axis filter capacitor voltage state variable and a D-axis filter capacitor voltage state variable by the state observer, wherein the Q-axis filter capacitor voltage state variables and the D-axis filter capacitor voltage state variables are voltage predicted values of the next sampling time.
11. The sensorless control method of filter capacitor current for a three-phase dc-to-ac converter of claim 10, further comprising:
and outputting a Q-axis disturbance voltage state variable and a D-axis disturbance voltage state variable by the state observer, wherein the Q-axis disturbance voltage state variable and the D-axis disturbance voltage state variable are voltage predicted values of the next sampling time.
12. A filter capacitor current sensorless control apparatus for a three-phase dc-ac converter for a state observer, comprising:
a chip, including a state observer, for capturing a dc link voltage, a first phase filter capacitor voltage actual value, a second phase filter capacitor voltage actual value, and a third phase filter capacitor voltage actual value of the three-phase dc-ac converter at the current sampling time, and for outputting a filter capacitor current state variable at the next sampling time by the state observer, wherein the filter capacitor current state variable is an average current value without ripple and is a current predicted value;
wherein the filter capacitor current state variable comprises:
a first line filter capacitor current state variable, a second line filter capacitor current state variable, and a third line filter capacitor current state variable; or
A Q-axis filter capacitor current state variable, and a D-axis filter capacitor current state variable.
13. The state observer sensorless control apparatus for filter capacitor current of a three-phase dc-to-ac converter as recited in claim 12, wherein the filter capacitor current state variables include a first phase filter capacitor current state variable, a second phase filter capacitor current state variable, and a third phase filter capacitor current state variable.
14. The apparatus of claim 13, wherein the state observer is configured to output a first phase filter capacitor voltage state variable, a second phase filter capacitor voltage state variable, and a third phase filter capacitor voltage state variable at the next sampling time, the first phase filter capacitor voltage state variable, the second phase filter capacitor voltage state variable, and the third phase filter capacitor voltage state variable being predicted values of the voltage at the next sampling time.
15. The filter capacitor current sensorless control apparatus of claim 14, wherein the state observer is configured to output a first phase disturbance voltage state variable, a second phase disturbance voltage state variable, and a third phase disturbance voltage state variable at the next sampling time, the first phase disturbance voltage state variables, the second phase disturbance voltage state variables, and the third phase disturbance voltage state variables being predicted voltage values at the next sampling time.
16. The sensorless filter capacitor current control apparatus of claim 15 wherein the state observer comprises a first phase state observer equation:
Figure FDA0003229077970000041
Figure FDA0003229077970000042
a first phase filter capacitor voltage state variable at the current sampling time;
Figure FDA0003229077970000043
the first phase filter capacitor voltage state variable at the next sampling time;
Figure FDA0003229077970000044
is the current sampling timeA first phase filter capacitor current state variable in between;
Figure FDA0003229077970000045
the first phase filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000046
a first phase disturbance voltage state variable of the current sampling time;
Figure FDA0003229077970000047
the first phase disturbance voltage state variable at the next sampling time; v. ofCa(k) The actual value of the voltage of the first-phase filter capacitor at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofa(k) Is a first phase modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
17. The state observer filter capacitor current sensorless control apparatus for a three-phase dc-to-ac converter as recited in claim 15, wherein the state observer comprises a second phase state observer equation:
Figure FDA0003229077970000048
Figure FDA0003229077970000049
a second phase filter capacitor voltage state variable at the current sampling time;
Figure FDA00032290779700000410
the second phase filter capacitor voltage state variable at the next sampling time;
Figure FDA00032290779700000411
a second phase filter capacitor current state variable at the current sampling time;
Figure FDA0003229077970000051
the second phase filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000052
a second phase disturbance voltage state variable at the current sampling time;
Figure FDA0003229077970000053
the second phase disturbance voltage state variable at the next sampling time; v. ofCb(k) The second-phase filter capacitor voltage actual value at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofb(k) A second phase modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
18. The sensorless filter capacitor current control apparatus of claim 15 wherein the state observer comprises a third phase state observer equation:
Figure FDA0003229077970000054
Figure FDA0003229077970000055
a third phase filter capacitor voltage state variable at the current sampling time;
Figure FDA0003229077970000056
the third phase filter capacitor voltage state variable at the next sampling time;
Figure FDA0003229077970000057
a third phase filter capacitor current state variable at the current sampling time;
Figure FDA0003229077970000058
the third phase filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000059
a third phase disturbance voltage state variable at the current sampling time;
Figure FDA00032290779700000510
the third phase disturbance voltage state variable at the next sampling time; v. ofCc(k) The third phase filter capacitor voltage actual value at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofc(k) Is a third phase modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
19. The apparatus of claim 12, wherein the state observer is configured to output a first line filter capacitor voltage state variable, a second line filter capacitor voltage state variable, and a third line filter capacitor voltage state variable at the next sampling time, the first line filter capacitor voltage state variables, the second line filter capacitor voltage state variables, and the third line filter capacitor voltage state variables being predicted values of the voltage at the next sampling time.
20. The device of claim 19, wherein the state observer is configured to output a first line disturbance voltage state variable, a second line disturbance voltage state variable, and a third line disturbance voltage state variable at the next sampling time, and the first line disturbance voltage state variables, the second line disturbance voltage state variables, and the third line disturbance voltage state variables are predicted voltage values at the next sampling time.
21. The sensorless control of filter capacitor current for a three-phase dc-to-ac converter of claim 20, wherein the state observer comprises a first line state observer equation:
Figure FDA0003229077970000061
Figure FDA0003229077970000062
a first line filter capacitor voltage state variable at the current sampling time;
Figure FDA0003229077970000063
the first line filter capacitor voltage state variable at the next sampling time;
Figure FDA0003229077970000064
a first line filter capacitor current state variable at the current sampling time;
Figure FDA0003229077970000065
the first line filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000066
a first line disturbance voltage state variable at the current sampling time;
Figure FDA0003229077970000067
the first line disturbance voltage state variable at the next sampling time; v. ofCab(k) A first line filter capacitor voltage actual value at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofab(k) Is a first line modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
22. The sensorless control of filter capacitor current for a three-phase dc-to-ac converter of claim 20, wherein the state observer comprises a second line state observer equation:
Figure FDA0003229077970000068
Figure FDA0003229077970000071
a second line filter capacitor voltage state variable at the current sampling time;
Figure FDA0003229077970000072
the second line filter capacitor voltage state variable at the next sampling time;
Figure FDA0003229077970000073
a second line filter capacitor current state variable at the current sampling time;
Figure FDA0003229077970000074
the second line filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000075
a second line disturbance voltage state variable at the current sampling time;
Figure FDA0003229077970000076
the second line disturbance voltage state variable at the next sampling time; v. ofCbc(k) The actual value of the voltage of the second line filter capacitor at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofbc(k) A second line modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
23. The condition observer, used in a filtered capacitor current sensorless control of a three-phase dc-to-ac converter, as recited in claim 20, wherein the condition observer comprises a third line condition observer equation:
Figure FDA0003229077970000077
Figure FDA0003229077970000078
a third line filter capacitor voltage state variable at the current sampling time;
Figure FDA0003229077970000079
the third line filter capacitor voltage state variable at the next sampling time;
Figure FDA00032290779700000710
a third line filter capacitor current state variable at the current sampling time;
Figure FDA00032290779700000711
the current state variable of the third line filter capacitor at the next sampling time;
Figure FDA00032290779700000712
a third line disturbance voltage state variable at the current sampling time;
Figure FDA00032290779700000713
the third line disturbance voltage state variable at the next sampling time; v. ofCca(k) The actual value of the voltage of the third line filter capacitor at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofca(k) Is a third line modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
24. The apparatus of claim 12, wherein the state observer is configured to output a Q-axis filter capacitor voltage state variable and a D-axis filter capacitor voltage state variable at the next sampling time, the Q-axis filter capacitor voltage state variables and the D-axis filter capacitor voltage state variables being predicted values of the voltage at the next sampling time.
25. The apparatus of claim 24, wherein the state observer is configured to output a Q-axis disturbance voltage state variable and a D-axis disturbance voltage state variable at the next sampling time, and the Q-axis disturbance voltage state variables and the D-axis disturbance voltage state variables are predicted voltage values at the next sampling time.
26. The sensorless control of filter capacitor current for a three-phase dc-to-ac converter of claim 25, wherein the state observer comprises a D-axis state observer equation:
Figure FDA0003229077970000081
Figure FDA0003229077970000082
a D-axis filter capacitor voltage state variable for the current sampling time;
Figure FDA0003229077970000083
the voltage state variable of the D-axis filter capacitor at the next sampling time;
Figure FDA0003229077970000084
a D-axis filter capacitor current state variable for the current sampling time;
Figure FDA0003229077970000085
the D-axis filter capacitor current state variable at the next sampling time;
Figure FDA0003229077970000086
a D-axis disturbance voltage state variable for the current sampling time;
Figure FDA0003229077970000087
the D-axis disturbance voltage state variable at the next sampling time; v. ofCd(k) A D-axis filter capacitor voltage actual value at the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofd(k) Is a D-axis modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
27. The sensorless control of filter capacitor current for a three-phase dc-to-ac converter of claim 25, wherein the state observer comprises a Q-axis state observer equation:
Figure FDA0003229077970000088
Figure FDA0003229077970000091
a Q-axis filter capacitor voltage state variable for the current sampling time;
Figure FDA0003229077970000092
the Q-axis filter capacitor voltage state variable at the next sampling time;
Figure FDA0003229077970000093
a Q-axis filter capacitor current state variable for the current sampling time;
Figure FDA0003229077970000094
the current state variable of the Q-axis filter capacitor at the next sampling time;
Figure FDA0003229077970000095
a Q-axis disturbance voltage state variable at the current sampling time;
Figure FDA0003229077970000096
the Q-axis disturbance voltage state variable at the next sampling time; v. ofCq(k) A Q-axis filter capacitor voltage actual value of the current sampling time; t is a sampling period; edIs the dc link voltage; u. ofq(k) Is a Q-axis modulation factor; l isfIs a filter inductor; cfIs a filter capacitor; k1、K2、K3Is a gain element; omegafIs a filtered angular frequency.
28. The sensorless control of filter capacitor current for a three-phase dc-to-ac converter as recited in claim 12, wherein the state observer comprises a gain matrix:
Figure FDA0003229077970000097
k is the gain matrix; k1、K2、K3Is the gain element of the gain matrix; omegafIs a filtering angular frequency; t is a sampling period; l isfIs a filter inductor; cfIs a filter capacitor.
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