Summary of the invention
The objective of the invention is to overcome above-mentioned the deficiencies in the prior art part, a kind of control method of numerically controlled inverter is provided; Utilize this control method can make the inverter dynamic response fast, steadily, the total percent harmonic distortion of output voltage is low under the nonlinear load situation, surpass under 3 the situation at specified nonlinear load, load current crest factor, the total percent harmonic distortion of output voltage is also lower, the stable state accuracy height, and simple in structure, cost is lower.
The control method of numerically controlled inverter provided by the invention, described inverter comprises inverter, the control input end and the microprocessor of inverter join, the output of inverter joins with the input of voltage sensor and load, the electric current of drawing in the inverter and the input of current sensor join, the direct-flow input end of inverter links to each other with DC power supply, and the output of voltage sensor and the output of current sensor join with microprocessor respectively; Described control method may further comprise the steps:
The 1st step was gathered the inverter output voltage u of the current bat k of voltage sensor output
0(k) and the output current i (k) of the current bat k of current sensor output;
The 2nd step utilized formula A to calculate the error intergal signal e of current bat k
i(k), e wherein
i(k-1) be the last one error intergal signal of clapping, its initial value is 0;
e
i(k)=e(k)+e
i(k-1) (A)
Wherein e (k) is current bat error signal, and its value equals the reference quantity u of current bat k
r(k) with the current output voltage u that claps k
0(k) difference;
It is load current i that the 3rd step was worked as the output current i that gathers
0The time, utilize the error intergal signal e of current bat
i(k) calculate the control signal u of next bat
1(k+1), u
1(k+1) be the control signal of next bat of inverter; Its processing procedure is:
The 3.1st step utilized formula D1 to calculate the output voltage measured value of next bat
Filter inductance electric current measured value with next bat
U wherein
1(k), i
0(k) and i
1(k) be respectively control signal, load current and the filter inductance electric current of current bat,
Be respectively output voltage measured value and the filter inductance electric current measured value of current bat k, T is the sampling period:
Wherein,
B
d=[H
1?H
2]
C
d=[1?0]
Natural frequency of oscillation for inverter
Damped oscillation frequency for inverter
L is the filter inductance of inverter, and C is the filter capacitor of inverter, and r is the equivalent damping resistance of inverter, and H is the feedback gain matrix of state observer;
The 3.2nd step utilized formula D2 to calculate the error signal measured value of next bat
Wherein
Reference quantity for next bat:
The 3.3rd step utilized formula D3 to calculate the error intergal signal measured value of next bat
The 3.4th step utilized formula D4 or formula D5-D6 to calculate the control signal u of next bat
1(k+1), wherein
Filter capacitor electric current measured value for next bat:
Wherein,
β
2, β
3And β
4Be respectively closed-loop pole Z by expectation
1, Z
2, Z
3Characteristic equation (the Z-Z that determines
1) (Z-Z
2) (Z-Z
3)=Z
3+ β
2Z
2+ β
3Z+ β
4In the quadratic term, once and the coefficient of constant term of expansion;
The 4th step was utilized control signal u
1(k+1) inverter is regulated;
The 5th step made k=k+1, repeated for the 1st step to the 4th step, until end-of-job.
The present invention compared with prior art has the following advantages:
(1) under the idle condition, it is short that the settling time of waveform is followed the tracks of in the inverter control system dynamic instruction that is made of augmented state feedback digital controller and inverter, is no more than 3.5ms, and overshoot is little, less than 9%.
When (2) load changing reached rated power, dynamic transition process was no more than 2ms, and the output voltage rate of change is no more than 10%, and workload-adaptability strengthens.
(3) under the various loading conditions from the zero load to the nominal load, all within 0.5%, steady-state error reduces the precision of voltage regulation greatly.
(4) the total percent harmonic distortion of output voltage is low under the nonlinear load situation, surpass under 3 the situation at specified nonlinear load, load current crest factor, the total percent harmonic distortion of output voltage is also lower, for example, at the electric current crest factor is 3.03 o'clock, THD=1.9% shows the wave distortion that nonlinear load is caused and has stronger inhibition ability.
(5) the present invention is in the design to inverter augmented state feedback digital controller Control Parameter, adopt STATE FEEDBACK CONTROL to realize any configuration of system's closed-loop pole, with stability, the dynamic property of safeguards system and reduce steady-state error, whole power-supply system has stronger robustness. under various load disturbance situation, all can obtain colory ac output voltage; Whole inverter system changes insensitive to inverter parameter, augmented state feedback digital controller parameter, the system responses performance is stable.
(6) circuit structure of the present invention is simple, and cost is low, is easy to realize.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in further detail.
As shown in Figure 1, the structure of the inverter of augmented state feedback digital control of the present invention is: the output of augmented state feedback digital controller 7 and the control input end of inverter 2 join, the input of the output of inverter 2 and voltage sensor 5 and load 3 are joined, the first via output of voltage sensor 5 and the negative input end of subtracter 8 join, and the positive input terminal of subtracter 8 receives reference quantity u
rThe input of the output of subtracter 8 and augmented state feedback digital controller 7 joins, the direct-flow input end of inverter 2 connects DC power supply 4, the input of electric current of drawing in the inverter 2 and current sensor 6 joins, and the second road output of the output of current sensor 6 and voltage sensor 5 joins with two inverting inputs of augmented state feedback digital controller 7 respectively.
Inverter 2, voltage sensor 5 and current sensor 6 can be selected common inverter, voltage sensor and current sensor for use.
Subtracter 8 and augmented state feedback digital controller 7 constitute microprocessor 1.Wherein microprocessor can be single-chip microcomputer or digital signal processing chip.
Microprocessor 1 is gathered the voltage signal of voltage sensor 5 outputs and the current signal of current sensor 6 outputs, according to electric current, voltage signal and reference quantity, and the calculation control signal, and export inverter 2 to, control inverter 2 work.
Microprocessor 1 and inverter 2 constitute an augmented state feedback digital control system, current i in the inverter 2 and output voltage u
0Enter microprocessor 1 through over-current sensor and voltage sensor respectively, microprocessor 1 is through producing control signal u behind the sequential operation
1Inverter 2 is implemented control, and wherein the current signal i in the inverter 2 can be the filter inductance current i
1, the filter capacitor current i
cWith load current i
0
The control method that augmented state feedback digital controller 7 is adopted the steps include: as shown in Figure 2
(1) gathers the output voltage u of the current bat that voltage sensor obtains
0(k) and the output current i (k) of the current bat that obtains of current sensor, calculate the error signal e (k) of current bat, e (k) equals the reference quantity u of current bat
r(k) with the output voltage u of current bat
0(k) difference; A sampling period T is called a bat in numerical control system, discrete constantly the expression with kT, be abbreviated as k, and represent k the discrete moment, its initial value is 0.
(2) utilize formula (A) to calculate the error intergal signal e of current bat
i(k), e wherein
i(k-1) be the last one error intergal signal of clapping, its initial value is 0;
e
i(k)=e(k)+e
i(k-1) (A)
(3) utilize the error intergal signal e of current bat
i(k) calculate the control signal u of next bat
1(k+1);
Because the current i in the inverter 2 comprises the filter inductance current i
1, the filter capacitor current i
cWith load current i
0,, adopt the control signal u of different next bats of algorithm computation according to the difference of the current signal of gathering
1(k+1), illustrated respectively below.
(3A) the current signal i when collection is the filter inductance current i
1The time, as shown in Figure 3, utilize formula (B) to calculate the control signal u of next bat
1(k+1), i wherein
1(k) be the filter inductance electric current of current bat:
u
1(k+1)=k
ie
i(k)-k
1u
0(k)-k
2i
1(k) (B)
Fig. 4 is corresponding with it schematic circuit block diagram.As shown in Figure 4, output voltage u
0With reference quantity u
rRelatively the error signal e of back generation produces error intergal signal e through integral element 9
i, error intergal signal e
iMultiply by integral coefficient k
iAfter deduct output voltage u
0With the Voltage Feedback coefficient k
1Product, deduct the filter inductance current i again
1With the current feedback coefficient k
2Product, last controlled signal u
1Inverter 2 is regulated.
(3B) the current signal i when collection is the filter capacitor current i
cThe time, as shown in Figure 5, utilize formula (C) to calculate the control signal u of next bat
1(k+1), i wherein
c(k) be the filter capacitor electric current of current bat:
u
1(k+1)=k
ie
i(k)-k
1u
0(k)-k
2i
c(k) (C)
Fig. 6 is corresponding with it schematic circuit block diagram.As shown in Figure 6, its structure is similar to Fig. 4, and difference is that the electric current of inverter 2 among Fig. 4 is filter inductance current i
1, and the electric current of inverter 2 is filter capacitor current i among Fig. 6
c
(3C) the current signal i when collection is load current i
0The time, as shown in Figure 7 and Figure 8, step (3) comprises following process:
(3C1) utilize formula (D1) to calculate the output voltage measured value of next bat
Filter inductance electric current measured value with next bat
I wherein
0(k) be the load current of current bat:
B
d=[H
1?H
2]
C
d=[1?0]
Natural frequency of oscillation for inverter 2
Damped oscillation frequency for inverter 2
Wherein L is the filter inductance of inverter 2, and C is the filter capacitor of inverter 2, and r is the equivalent damping resistance of inverter 2;
H is the feedback gain matrix of state observer 10, according to (A
d-HC
d) characteristic value select feedback gain matrix H to get final product than the fast principle more than 5 times of the closed loop characteristic value of inverter 2.
(3C2) utilize formula (D2) to calculate the error signal measured value of next bat
(3C3) utilize formula (D3) to calculate the error intergal signal measured value of next bat
(3C4) utilize formula (D4) or formula (D5)-(D6) to calculate the control signal u of next bat
1(k+1), wherein
Filter capacitor electric current measured value for next bat:
Fig. 9 is the schematic circuit block diagram corresponding with Fig. 7 and Fig. 8.As shown in Figure 9, its structure is similar to Fig. 4, and difference is that the electric current of inverter 2 among Fig. 4 is filter inductance current i
1, and the electric current of inverter 2 is load current i among Fig. 9
0 Comprise state observer 10 in the augmented state feedback digital controller 7 among Fig. 9.
State observer 10 is according to the output voltage u of current bat
0(k) and the load current i of current bat
0(k) observe the output voltage measured value of next bat
Filter inductance electric current measured value with next bat
Its computing formula is formula (D1).
Three state variables, i.e. output voltage u are arranged in the augmented state feedback digital control system
0, the filter inductance current i
1(filter capacitor current i
c) and error intergal signal e
i, three state variables respectively corresponding three Control Parameter, i.e. Voltage Feedback coefficient k
1, the current feedback coefficient k
2With integral coefficient k
iThe design key of augmented state feedback digital controller 7 is determining of its three Control Parameter.
If the state feedback gain matrix is:
K=[k
1?k
2?k
i]
Closed-loop pole Z by expectation
1, Z
2, Z
3The characteristic equation of determining is:
(Z-Z
1)(Z-Z
2)(Z-Z
3)=Z
3+β
2Z
2+β
3Z+β
4
β in the following formula
2, β
3And β
4Be respectively the quadratic term of characteristic equation expansion, once and the coefficient of constant term.
Relatively can get:
Wherein
In the above-mentioned derivation with the filter inductance current i
1As a state variable, if use the filter capacitor current i
cReplace inductive current i
1As state variable, because of the system features equation is identical, so Control Parameter is still determined by top three formulas.
(4) utilize control signal u
1(k+1) inverter 2 is regulated;
(5) make k=k+1, repeating step (1)-(4) are until end-of-job.