CN102013824A - Controller for inhibiting neutral point potential drift in three-level inverter - Google Patents
Controller for inhibiting neutral point potential drift in three-level inverter Download PDFInfo
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Abstract
The invention relates to a controller for inhibiting neutral point potential drift in a three-level inverter. The controller comprises a vector partition judging module, a base vector duty ratio calculation module, a neutral point potential balance control module and a PWM (Pulse-Width Modulation) on-off signal output module. The input signals of the controller comprise modulation degree and frequency. The output signals of the controller comprise six pairs of PWM on-off control signals. The neutral point potential balance control module is used for calculating balance distribution coefficients and distributing the respective action time of two redundancy small vectors according to the real-time measurement values of phase current size and direction in each PWM period so as to achieve the purpose of compensating the action of a middle vector and inhibiting neutral point potential drift. The balance distribution coefficients comprise a first balance distribution coefficient corresponding to a first redundancy small vector and a second balance distribution coefficient corresponding to a second redundancy small vector. The controller can accurately, correctly and quickly inhibit neutral point potential drift.
Description
Technical field
The present invention relates to the control device of motor, relate in particular to the inverter control of three phase electric machine.
Background technology
Multi-electrical level inverter is owing to have the efficient height, and dynamic property is good, and is less to the harmonic wave that motor produces, and is fit to advantages such as high-voltage large-capacity occasion, obtained in high-voltage large-capacity AC speed regulating field using widely.Wherein, the diode-clamped three-level inverter is wherein a kind of topological structure commonly used, and still, the midpoint potential equilibrium problem in this structure is more and more paid attention to.Operation logic by analyzing this topological structure as can be known, the influential effect of alignment current potential be redundant small vector and middle vector in the basic voltage vectors.In essence, cause, depend on factors such as duration of direction, pulse of selection, the load current of switching mode and dc bus capacitor size by the dc partial voltage capacitor charge and discharge is unbalanced.According to three dimensional vector diagram as can be known, because middle vector does not have redundant vector, so vector is controlled mid-point voltage in can't utilizing, and there is a redundant vector in each small vector, and the influence of these two small vector alignment voltages is opposite exactly, thereby can further utilize the characteristics of the influence of small vector alignment voltage, suppress the drift of three-level inverter midpoint potential, reach the purpose of control midpoint potential balance.
Summary of the invention
The technical problem to be solved in the present invention is to overcome above-mentioned the deficiencies in the prior art, and proposes a kind of controller that can realize accurately, accurately and apace that the midpoint potential drift suppresses.
The present invention solves the problems of the technologies described above the technological means that is adopted and comprises, a kind of controller that is used to suppress the drift of three-level inverter midpoint potential is proposed, this controller comprises vector subregion judge module, basic vector duty ratio computing module, midpoint potential Balance Control module and pwm switching signal output module, the input signal of this controller comprises modulation degree and frequency, the output signal of this controller comprises six pairs of PWM switch controlling signals, this midpoint potential Balance Control module is in each PWM cycle, measured value according to real-time phase current size and Orientation, calculated equilibrium distribution coefficient and the action time separately of distributing two redundant small vectors, come effect to vector in to compensate and the drift of midpoint potential is inhibited, this equilibrium distribution coefficient comprises corresponding to first equilibrium distribution coefficient of first redundant small vector with corresponding to second equilibrium distribution coefficient of second redundant small vector.
In the present invention, this midpoint potential Balance Control module is to be added to next PWM cycle fail the mid point current value of full remuneration in the current PWM cycle, and the effect of the middle vector that produces with following one-period is compensated in the lump.
In the present invention, equilibrium distribution coefficient in this midpoint potential Balance Control module also distributes the strategy of calculating of the action time separately of two redundant small vectors to comprise: first first redundant small vector resultant action time of small vector positive acting time=the first equilibrium distribution coefficient *, first small vector acting in opposition time=first redundant small vector resultant action time of (1-first equilibrium distribution coefficient) *; Second second redundant small vector resultant action time of small vector positive acting time=the second equilibrium distribution coefficient *, second small vector acting in opposition time=second redundant small vector resultant action time of (1-second equilibrium distribution coefficient) *.
In the present invention, the equilibrium distribution coefficient in this midpoint potential Balance Control module and distribute the strategy of calculating of the action time separately of two redundant small vectors also to comprise:
First kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that vector causes in being somebody's turn to do is minimum, if the mid point electric current that causes of this first redundant small vector be on the occasion of, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor+0.5* adjusted in this first equilibrium distribution coefficient=biasing, if the mid point electric current that this first redundant small vector causes is a negative value, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor-0.5* adjusted in this first equilibrium distribution coefficient=1-biasing, if the mid point electric current that causes of this second redundant small vector be on the occasion of the time, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor-0.5* adjusted in this second equilibrium distribution coefficient=1-biasing, if the mid point electric current that this second redundant small vector causes is a negative value, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor+0.5* adjusted in this second equilibrium distribution coefficient=biasing;
Second kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that this first redundant small vector causes is minimum, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is with symbol, this first equilibrium distribution coefficient=1, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is anti-symbol, this first equilibrium distribution coefficient=0, if the mid point electric current that causes of this second redundant small vector be on the occasion of the time, the absolute value of the mid point electric current that the redundant small vector of the factor-0.5* (absolute value of the absolute value of the mid point electric current that middle vector causes-mid point electric current that first redundant small vector causes)/second causes is adjusted in the biasing of this second equilibrium distribution coefficient=1-, if the mid point electric current that causes of this second redundant small vector is a negative value, the absolute value of the mid point electric current that the redundant small vector of this second equilibrium distribution coefficient=biasing adjustment factor+0.5* (absolute value of the absolute value of the mid point electric current that middle vector causes-mid point electric current that first redundant small vector causes)/second causes;
The third situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that this second redundant small vector causes is minimum, if the mid point electric current that causes of this first redundant small vector be on the occasion of the time, the absolute value of the factor+0.5* (absolute value of the mid point electric current that the absolute value-second of the mid point electric current that middle vector causes a redundant small vector causes)/mid point electric current that first redundant small vector causes is adjusted in this first equilibrium distribution coefficient=biasing, if the mid point electric current that this first redundant small vector causes is a negative value, the factor-0.5* (absolute value of (absolute value of the mid point electric current that the absolute value-second of the mid point electric current that middle vector causes a redundant small vector causes)/mid point electric current that first redundant small vector causes is adjusted in this second equilibrium distribution coefficient=1-biasing, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is with symbol, this second equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is anti-symbol, this second equilibrium distribution coefficient=1;
The 4th kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that the absolute value sum of the mid point electric current that these two redundant small vectors cause causes less than vector in this, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is with symbol, this first equilibrium distribution coefficient=1, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is anti-symbol, this first equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is with symbol, this second equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is anti-symbol, this second equilibrium distribution coefficient=1;
Wherein, this biasing adjustment factor is to be used for controlling forcibly when unusual mid-point voltage occurring the mid-point voltage value.
Wherein, the value of this biasing adjustment factor is 0.5.
In the present invention, this controller can be to adopt a digital signal processor to realize.
In the present invention; this controller also can comprise a mid-point voltage Monitoring and Controlling module; it links to each other with this midpoint potential Balance Control module; this mid-point voltage Monitoring and Controlling module is to detect the variation of midpoint potential in real time, and sends a control command to this midpoint potential Balance Control module force this midpoint potential Balance Control module to take other control strategy or shut down to handle to guarantee the reliability of inverter system when this midpoint potential exceeds a preset threshold value.
In the present invention, this mid-point voltage Monitoring and Controlling module comprises a hysteresis comparing unit and an order generating unit, the input signal of this hysteresis comparing unit is the mid-point voltage value that obtains of actual measurement and the difference of desirable mid-point voltage value, the output signal of this hysteresis comparing unit is to be determined by the difference of this input and this preset threshold value, this control command of output after this order generating unit is tabled look-up according to the output signal of this hysteresis comparing unit.
In the present invention, the output signal of this hysteresis comparing unit is the two digits form, can provide distinctively this difference less than the lower limit of preset threshold value, this difference greater than the upper limit of preset threshold value and this difference three kinds of states between the lower limit of this preset threshold value and the upper limit.
Wherein, this ideal mid-point voltage value be busbar voltage half.
Compared with prior art, the controller that is used to suppress the drift of three-level inverter midpoint potential of the present invention, comprise two-part setting, first is a midpoint potential Balance Control module, utilize the measured value of real-time phase current size and Orientation, calculated equilibrium distribution coefficient, the action time separately of distributing two redundant small vectors, make midpoint potential reach theoretic no drift phenomenon, can realize accurately, accurately and apace that the midpoint potential drift suppresses; Second portion is a mid-point voltage Monitoring and Controlling module, monitors the variation of midpoint potential in real time, then takes other control strategy or shuts down processing if current potential surpasses threshold value, guarantees the reliability of system.
Description of drawings
Fig. 1 is the allomeric function block diagram of controller of the present invention.
Fig. 2 is the application block diagram of controller of the present invention in three phase electric machine control.
Fig. 3 is the main program flow of controller of the present invention.
Fig. 4 is the program flow diagram of the midpoint potential Balance Control module in the controller of the present invention.
Fig. 5 is the functional block diagram of the mid-point voltage Monitoring and Controlling module in the controller of the present invention.
Fig. 6 is the program flow diagram of the mid-point voltage Monitoring and Controlling module in the controller of the present invention.
Embodiment
In order to further specify principle of the present invention and structure, existing in conjunction with the accompanying drawings to a preferred embodiment of the present invention will be described in detail.
As shown in Figure 1, controller input signal is voltage modulated degree and frequency, by six pairs of PWM switch command signal of module output such as the judgement of vector subregion, the calculating of basic vector duty ratio, midpoint potential balance controller and the controls of the switching signal way of output, produce stable no harmonic wave three level voltage waveforms.Wherein judgement of vector subregion and the calculating of basic vector duty ratio are identical with traditional controller, and design focal point of the present invention is the midpoint potential balance controller.As shown in Figure 2, the vector subregion judge module in this controller, basic vector duty ratio computing module, midpoint potential Balance Control module and pwm switching signal output module can be realized by a DSP (digital signal processor).Fig. 3 is the main program flow of controller of the present invention.As shown in Figure 4, be neutral balance control algolithm flow process.
At first define following variable:
The resultant action time of redundant small vector xp and xn: t1
The resultant action time of redundant small vector yp and yn: t3
The action time of middle vector z: t2
T1, t2, t3 can calculate and can get according to the weber balance principle of traditional SVPWM, and computing formula is as follows
Wherein T is the time in a PWM cycle, and v is the voltage vector that will synthesize in the current PWM cycle.
The mid point electric current that is produced by middle vector z is: ic
The mid point electric current that is produced by xp and xn is: icx
The mid point electric current that is produced by yp and yn is: icy
The real-time three-phase current of measuring gained is respectively: i (U), i (V), i (W)
The output current that xp and xn do the time spent is: i (x)
The output current that yp and yn do the time spent is: i (y)
The output current that z does the time spent is: i (z); The corresponding relation of they and actual three-phase current is:
icx＝i(x)×t1
icy＝i(y)×t3
ic＝i(z)×t2
The then real-time magnitude of current that flows to mid point is:
Calculate mid point current i c, icx, after the value of icy, by definite xp, xn and yp, ratio action time of yn can make mid point electric current total amount equal zero, thereby keeps the balance of midpoint potential.If the midpoint potential equilibrium distribution coefficient is α, α 1, and α 2, and three's the relation mode of clicking determines:
As i (x) 〉=0, α 1=α
As i (x)＜0, α 1=1-α
As i (y) 〉=0, α 2=1-α
As i (y)＜0, α 2=α
(when establishing electric current from inverter inflow motor is positive direction)
The action time of xp and xn, ratio was so:
The action time of xp: Txp=α 1 * t1,
The action time of xn: Txn=(1-α 1) * t1
And ratio is the action time of yp and yn:
The action time of yp: Typ=α 2 * t3,
The action time of yn: Tyn=(1-α 2) * t3
Therefore PWM total current of flowing to mid point in the cycle is:
i
n＝i
x·(T
xp-T
xn)+i
y·(T
yp-T
yn)+i
z·t2
＝i
x·(1-2α
1)·t1+i
y·(1-2α
2)·t3+i
z·t2
So midpoint potential distribution coefficient α can be according to parameter a ' and α " calculate by following formula:
α＝α′+α″(0≤α≤1)
Wherein a ' can be calculated by following formula:
D＝γ/(2×β)
a′＝D(when ic≥0)
a′＝-D(when ic＜0)
(0≤α′≤1)
" adjust the factor for biasing, control the mid-point voltage value forcibly when being used to unusual mid-point voltage occur, its value generally gets 0.5 to α.
Then β and γ obtain respectively according to following 4 kinds of situations.
When | ic|＜| icx|≤| icy| or | ic|＜| icy|≤| during icx|,
γ＝ic，β＝|icx|+|icy|
When | icx|≤| ic|≤| icy| or | icx|≤| icy|≤| during ic|,
γ＝|ic|-|icx|，β＝|icy|
At this moment, α 1 is obtained by following two kinds of different situations: α 1=1 when i cx is identical with i c symbol; When icx and ic opposite in sign, α 1=0; A2 obtains according to the calculated value of D according to aforementioned formula.
When | icy|≤| ic|≤| icx| or | icy|≤| icx|≤| during ic|,
γ＝|ic|-|icy|，β＝|icx|
This moment, α 2 was obtained by following two kinds of different situations: α 2=0 when icy is identical with the ic symbol; When icy and ic opposite in sign, α 2=1; A1 obtains according to the calculated value of D according to aforementioned formula.
When | icx|+|icy|≤| during ic|,
And: when icx is identical with the ic symbol, α 1=1;
When icx and ic opposite in sign, α 1=0;
When icy is identical with the ic symbol, α 2=0;
When icy and ic opposite in sign, α 2=1;
Obtain suitable midpoint potential equilibrium distribution coefficient α according to above algorithm computation, at a PWM in the cycle, mid point electric current and two redundant small vector xp of causing by middle vector z, xn, yp, the mid point electric current that yn causes offsets, and total mid point current i n is equalled zero, thereby has guaranteed the balance of midpoint potential.
As ic too big so that a PWM in the cycle icx and icy can't be fully and its counteracting alignment electric current do the time spent need improve control algolithm.Promptly calculate current period by the mid point current value ic0 that fails full remuneration that middle vector z causes, it is joined next PWM in the cycle, the mid point electric current that produces with following one-period compensates in the lump.The ic of following one-period of this moment is:
ic＝ic0+i(z)×t2
Can suppress the drift of midpoint potential effectively by above processing method.Wherein the value of ic0 can be obtained by the transducer of measuring the mid point electric current, or obtains by the calculated value of last one-period.
Figure 5 shows that mid-point voltage monitoring module block diagram.Fig. 6 is the program flow diagram of the mid-point voltage Monitoring and Controlling module in the controller of the present invention.This module is monitored the variation of midpoint potential in real time, not only can avoid by some control at the little noise jamming midpoint potential of tolerance interval, and can take other control strategy immediately or shut down processing when current potential surpasses threshold value, guarantees the reliability of system.
This module is by by hysteresis loop comparator, and buffer circuit and command generator are formed.The input signal of hysteresis loop comparator is the mid-point voltage value V of actual measurement
CNWith desirable mid-point voltage
The difference of (be busbar voltage half), output signal is the two digits signal.The digital signal of output is by the difference of input and the threshold value decision of setting.When difference is lower than lower threshold value, greater than upper threshold value or be in lower threshold value and upper threshold value between the time, represent three kinds of different situations with different two digits signals respectively.Mid-point voltage control command generator receives the result of hysteresis loop comparator, according to the running status-electronic/generating state of current inversion system, by the output mid-point voltage control command of tabling look-up.Form is as follows:
Last tabular goes out the change situation of each on off state alignment voltage, the corresponding output voltage vector of each on off state.The mid-point voltage supervisory control device is according to last table and invertor operation situation and small vector redundancy output mid-point voltage control command.For example the line voltage of their output of xp vector and xn vector is identical, but corresponding on off state and different.Suppose that motor runs on motoring condition, according to the change effect of their alignment voltage, xp improves mid-point voltage, and xn is then just opposite.Even specified the voltage vector that to export like this, still can select different on off states according to the direction of the mid-point voltage that will adjust.The relation of on off state and mid-point voltage will leave in the mid-point voltage control command generator in advance, can select different on-off modes to realize the balance of midpoint potential according to the variation of mid-point voltage like this.
In addition, also can set the threshold to a limiting value, when mid-point voltage exceeded threshold range, the control command generator was exported halt command at once, had further guaranteed the fail safe of system.
Compared with prior art, the controller that is used to suppress the drift of three-level inverter midpoint potential of the present invention, problem at the midpoint potential drift of diode-clamped tri-level inversion system, utilize the redundancy of the space voltage basic vector of output, make control system can control midpoint potential accurately, accurately and rapidly, the balance that keeps midpoint potential, problems such as the output waveform distortion of avoiding producing, system reliability reduction by the current potential drift.
The diode-clamped three-level converter adopts two capacitances in series to produce three level, and therefore the magnitude of current difference of the inflow mid point of different switch vector correspondences may produce floating of midpoint potential.If the midpoint potential imbalance of three level not only can produce low-order harmonic at the interchange outlet side, make the delivery efficiency step-down of inverter, and also can produce pulsating torque motor with time-harmonic wave, influence the speed adjusting performance of motor; Some switching tube of inverter voltage increases of bearing can cause switching device to puncture when serious in addition, thereby has reduced the reliability of system; The fluctuation of midpoint potential also can reduce the life-span of dc bus capacitor.This invention The controller can suppress the drift of midpoint potential effectively and improve the safety and the quality of output voltage.
For reaching the purpose of control mid-point voltage, controller at first will calculate t2 action time of vector in the output (being the basic voltage vectors that three-phase output end is connected to bus positive pole, bus negative pole and mid point), obtains the magnitude of current that flows to mid point of definite direction of expecting thus; Calculate then two redundant small vectors being in the same vector subregion (three-phase output end of one of them small vector wherein two be connected to bus positive pole or mid point, remaining one is connected to mid point or bus negative pole; The state of another small vector is opposite states therewith) t1 action time, t3, and calculate equilibrium distribution coefficient, also obtained the magnitude of current that flows to mid point of these two pairs of definite directions that small vector produced thus.Based on above three magnitudes of current that calculate, cooperate the specific basic vector way of output, three's sum is just equalled zero, the electric current total amount that promptly flows to mid point is zero, thereby keeps the balance of midpoint potential.For improving the reliability of system, added a hysteresis loop comparator in the controller of design, monitor the variation of midpoint potential in real time.If the drift value of midpoint potential exceeds preset threshold, need take other specific control strategy or shut down processing.
Below only be preferable possible embodiments of the present invention, and unrestricted protection scope of the present invention, so the equivalent structure that all utilizations specification of the present invention and accompanying drawing content are made changes, all be included in protection scope of the present invention.
Claims (10)
1. controller that is used to suppress the drift of three-level inverter midpoint potential, this controller comprises vector subregion judge module, basic vector duty ratio computing module, midpoint potential Balance Control module and pwm switching signal output module, the input signal of this controller comprises modulation degree and frequency, the output signal of this controller comprises six pairs of PWM switch controlling signals, it is characterized in that, this midpoint potential Balance Control module is in each PWM cycle, measured value according to real-time phase current size and Orientation, calculated equilibrium distribution coefficient and the action time separately of distributing two redundant small vectors, come effect to vector in to compensate and the drift of midpoint potential is inhibited, this equilibrium distribution coefficient comprises corresponding to first equilibrium distribution coefficient of first redundant small vector with corresponding to second equilibrium distribution coefficient of second redundant small vector.
2. according to the described controller of claim 1, it is characterized in that, this midpoint potential Balance Control module is to be added to next PWM cycle fail the mid point current value of full remuneration in the current PWM cycle, and the effect of the middle vector that produces with following one-period is compensated in the lump.
3. according to the described controller of claim 1, it is characterized in that, equilibrium distribution coefficient in this midpoint potential Balance Control module also distributes the strategy of calculating of the action time separately of two redundant small vectors to comprise: first first redundant small vector resultant action time of small vector positive acting time=the first equilibrium distribution coefficient *, first small vector acting in opposition time=first redundant small vector resultant action time of (1-first equilibrium distribution coefficient) *; Second second redundant small vector resultant action time of small vector positive acting time=the second equilibrium distribution coefficient *, second small vector acting in opposition time=second redundant small vector resultant action time of (1-second equilibrium distribution coefficient) *.
4. according to the described controller of claim 3, it is characterized in that the equilibrium distribution coefficient in this midpoint potential Balance Control module also distributes the strategy of calculating of the action time separately of two redundant small vectors also to comprise:
First kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that vector causes in being somebody's turn to do is minimum, if the mid point electric current that causes of this first redundant small vector be on the occasion of, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor+0.5* adjusted in this first equilibrium distribution coefficient=biasing, if the mid point electric current that this first redundant small vector causes is a negative value, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor-0.5* adjusted in this first equilibrium distribution coefficient=1-biasing, if the mid point electric current that causes of this second redundant small vector be on the occasion of the time, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor-0.5* adjusted in this second equilibrium distribution coefficient=1-biasing, if the mid point electric current that this second redundant small vector causes is a negative value, absolute value/(absolute value of the mid point electric current that absolute value+second of the mid point electric current that first redundant small vector causes a redundant small vector causes) of the mid point electric current that vector causes among the factor+0.5* adjusted in this second equilibrium distribution coefficient=biasing;
Second kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that this first redundant small vector causes is minimum, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is with symbol, this first equilibrium distribution coefficient=1, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is anti-symbol, this first equilibrium distribution coefficient=0, if the mid point electric current that causes of this second redundant small vector be on the occasion of the time, the absolute value of the mid point electric current that the redundant small vector of the factor-0.5* (absolute value of the absolute value of the mid point electric current that middle vector causes-mid point electric current that first redundant small vector causes)/second causes is adjusted in the biasing of this second equilibrium distribution coefficient=1-, if the mid point electric current that causes of this second redundant small vector is a negative value, the absolute value of the mid point electric current that the redundant small vector of this second equilibrium distribution coefficient=biasing adjustment factor+0.5* (absolute value of the absolute value of the mid point electric current that middle vector causes-mid point electric current that first redundant small vector causes)/second causes;
The third situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that this second redundant small vector causes is minimum, if the mid point electric current that causes of this first redundant small vector be on the occasion of the time, the absolute value of the factor+0.5* (absolute value of the mid point electric current that the absolute value-second of the mid point electric current that middle vector causes a redundant small vector causes)/mid point electric current that first redundant small vector causes is adjusted in this first equilibrium distribution coefficient=biasing, if the mid point electric current that this first redundant small vector causes is a negative value, the factor-0.5* (absolute value of (absolute value of the mid point electric current that the absolute value-second of the mid point electric current that middle vector causes a redundant small vector causes)/mid point electric current that first redundant small vector causes is adjusted in this second equilibrium distribution coefficient=1-biasing, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is with symbol, this second equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is anti-symbol, this second equilibrium distribution coefficient=1;
The 4th kind of situation: in the absolute value three of the mid point electric current that the absolute value of the mid point electric current that middle vector causes and two redundant small vectors cause, the absolute value of the mid point electric current that the absolute value sum of the mid point electric current that these two redundant small vectors cause causes less than vector in this, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is with symbol, this first equilibrium distribution coefficient=1, if the mid point electric current that mid point electric current that this first redundant small vector causes and middle vector cause is anti-symbol, this first equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is with symbol, this second equilibrium distribution coefficient=0, if the mid point electric current that mid point electric current that this second redundant small vector causes and middle vector cause is anti-symbol, this second equilibrium distribution coefficient=1;
Wherein, this biasing adjustment factor is to be used for controlling forcibly when unusual mid-point voltage occurring the mid-point voltage value.
5. according to the described controller of claim 4, it is characterized in that the value that the factor is adjusted in this biasing is 0.5.
6. according to the described controller of claim 1, it is characterized in that this controller is to adopt a digital signal processor to realize.
7. according to the described controller of claim 1; it is characterized in that; this controller also comprises a mid-point voltage Monitoring and Controlling module; it links to each other with this midpoint potential Balance Control module; this mid-point voltage Monitoring and Controlling module is to detect the variation of midpoint potential in real time, and sends a control command to this midpoint potential Balance Control module force this midpoint potential Balance Control module to take other control strategy or shut down to handle to guarantee the reliability of inverter system when this midpoint potential exceeds a preset threshold value.
8. according to the described controller of claim 7, it is characterized in that, this mid-point voltage Monitoring and Controlling module comprises a hysteresis comparing unit and an order generating unit, the input signal of this hysteresis comparing unit is the mid-point voltage value that obtains of actual measurement and the difference of desirable mid-point voltage value, the output signal of this hysteresis comparing unit is to be determined by the difference of this input and this preset threshold value, this control command of output after this order generating unit is tabled look-up according to the output signal of this hysteresis comparing unit.
9. according to the described controller of claim 8, it is characterized in that, the output signal of this hysteresis comparing unit is the two digits form, can provide distinctively this difference less than the lower limit of preset threshold value, this difference greater than the upper limit of preset threshold value and this difference three kinds of states between the lower limit of this preset threshold value and the upper limit.
10. according to the described controller of claim 8, it is characterized in that this ideal mid-point voltage value is half of busbar voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010294008 CN102013824A (en) | 2010-09-21 | 2010-09-21 | Controller for inhibiting neutral point potential drift in three-level inverter |
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| CN103051227A (en) * | 2012-12-21 | 2013-04-17 | 燕山大学 | Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter |
| CN103138594A (en) * | 2011-11-22 | 2013-06-05 | 通用电气公司 | Control system, control method and compensation control unit of NPC (neutral point clamping) converter |
| CN103138595A (en) * | 2011-11-22 | 2013-06-05 | 通用电气公司 | Control system and method of NPC (neutral point clamping) converter |
| CN103136066A (en) * | 2011-11-25 | 2013-06-05 | 英业达股份有限公司 | Processing device and method for voltage error |
| CN103236797A (en) * | 2013-04-17 | 2013-08-07 | 西安交通大学 | Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter |
| CN103414366A (en) * | 2013-07-24 | 2013-11-27 | 西安龙腾新能源科技发展有限公司 | Neutral point potential balance control method for direct current side in NPC three-level structure |
| CN105680711A (en) * | 2016-03-22 | 2016-06-15 | 山东大学 | SHEPWM adopted T type three-level inverter neutral-point voltage balance control method |
| CN108983658A (en) * | 2018-07-11 | 2018-12-11 | 佛山市众盈电子有限公司 | A kind of three level ups power monitoring systems |
| CN110971162A (en) * | 2019-12-11 | 2020-04-07 | 浙江大学 | Improved model prediction torque control method of NPC three-level converter-PMSM system |
| CN113078833A (en) * | 2021-04-15 | 2021-07-06 | 广州工程技术职业学院 | Vienna rectifier midpoint potential oscillation control method, system and device |
| CN113783453A (en) * | 2021-09-29 | 2021-12-10 | 山东建筑大学 | Low-cost high-gain three-level inverter and space vector modulation method thereof |
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| CN103138594A (en) * | 2011-11-22 | 2013-06-05 | 通用电气公司 | Control system, control method and compensation control unit of NPC (neutral point clamping) converter |
| CN103138595A (en) * | 2011-11-22 | 2013-06-05 | 通用电气公司 | Control system and method of NPC (neutral point clamping) converter |
| CN103138595B (en) * | 2011-11-22 | 2016-05-25 | 通用电气公司 | The control system of neutral point clamped multi current transformer and control method |
| CN103138594B (en) * | 2011-11-22 | 2016-03-02 | 通用电气公司 | The control system of neutral point clamped multi current transformer and control method and compensatory control unit |
| CN103136066A (en) * | 2011-11-25 | 2013-06-05 | 英业达股份有限公司 | Processing device and method for voltage error |
| CN103136066B (en) * | 2011-11-25 | 2015-09-23 | 英业达股份有限公司 | The treating apparatus of voltage error and method |
| CN103051227A (en) * | 2012-12-21 | 2013-04-17 | 燕山大学 | Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter |
| CN103051227B (en) * | 2012-12-21 | 2015-04-29 | 燕山大学 | Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter |
| CN103236797B (en) * | 2013-04-17 | 2015-07-01 | 西安交通大学 | Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter |
| CN103236797A (en) * | 2013-04-17 | 2013-08-07 | 西安交通大学 | Method for controlling balance of capacitive voltages of five-level diode neutral point clamped converter |
| WO2015010225A1 (en) * | 2013-07-24 | 2015-01-29 | 西安龙腾新能源科技发展有限公司 | Control method for neutral-point potential balance on dc side in npc three-level structure |
| CN103414366A (en) * | 2013-07-24 | 2013-11-27 | 西安龙腾新能源科技发展有限公司 | Neutral point potential balance control method for direct current side in NPC three-level structure |
| CN103414366B (en) * | 2013-07-24 | 2016-06-08 | 西安龙腾新能源科技发展有限公司 | The control method of DC side neutral-point potential balance in NPC three-level structure |
| CN105680711A (en) * | 2016-03-22 | 2016-06-15 | 山东大学 | SHEPWM adopted T type three-level inverter neutral-point voltage balance control method |
| CN108983658A (en) * | 2018-07-11 | 2018-12-11 | 佛山市众盈电子有限公司 | A kind of three level ups power monitoring systems |
| CN110971162A (en) * | 2019-12-11 | 2020-04-07 | 浙江大学 | Improved model prediction torque control method of NPC three-level converter-PMSM system |
| CN110971162B (en) * | 2019-12-11 | 2021-04-06 | 浙江大学 | Model prediction torque control method of NPC three-level converter-PMSM system |
| CN113078833A (en) * | 2021-04-15 | 2021-07-06 | 广州工程技术职业学院 | Vienna rectifier midpoint potential oscillation control method, system and device |
| CN113783453A (en) * | 2021-09-29 | 2021-12-10 | 山东建筑大学 | Low-cost high-gain three-level inverter and space vector modulation method thereof |
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