CN101222186B - Output current control method for AC power supply device - Google Patents

Abstract

An output current controlling method of an AC power supply device controls a DC/AC conversion device to stop outputting by an output voltage stop signal, detects output current of the DC/AC conversion device during the period of stop outputting, and feeds back the output current to a current control device to generate a magnitude of error, after the magnitude of error is deducted by an output current feedback signal of the DC/AC conversion device, a calculation is executed in a section to obtain a DC approximate value contained in the output current of the DC/AC conversion device, the DC/AC conversion device can be controlled through referring to the DC approximate value, so that DC component of the output current can be close to zero.

Description

The output current control method of AC power supply device

Technical field

The present invention relates to a kind of output current control method of AC power supply device.

Background technology

For AC power supply device, harmonic components and flip-flop (DCcomponent) contained in its output current must be suppressed.Wherein a kind of mode of inhibition is to add an isolating transformer to reach, but its shortcoming is this isolating transformer and can causes the part power loss of AC power supply device, and because this isolating transformer is to adopt outer add mode, so all can improve relatively no matter the whole generating device is cost or volume.

And another practice as shown in figure 15, is that a Germany checks and approves No. 10249122 employed technology of patent case of bulletin DE, also can reach the purpose that suppresses flip-flop.This patent is to use a capacitor that adds (Cm) as current sensor, voltage conversion by this capacitor (Cm) two ends obtains the output current back coupling, but output current must upward form a voltage drop because of charge storage effects at capacitor (Cm), if must reduce the sensing voltage of capacitor, then this capacitor itself is necessary for a large-sized AC capacitor, but its cost and volume problem are the shortcoming of Blast Furnace Top Gas Recovery Turbine Unit (TRT) equally.

Summary of the invention

Technical problem underlying to be solved by this invention is, overcome the existing technology of controlling output current flip-flop now nothing more than being to add isolating transformer or capacitor, all can make the volume of AC power supply device more huge and make the high shortcoming of manufacturing cost, and a kind of output current control method of AC power supply device is provided, and flip-flop in the output current can be controlled to be level off to zero.

AC power supply device of the present invention is:

A kind of AC power supply device is characterized in that, comprising: a direct current power supply provides DC power supply; One DC/AC switching device, the conversion DC power supply is an AC power; One output current sensing apparatus is detected the output current of this DC/AC switching device, and produces an output current feedback signal according to this; One output current control device receives aforementioned output current feedback signal and controls this DC/AC switching device; Wherein, when the output current control device produces an output voltage stop signal and stops to export to control this DC/AC switching device, the output current feedback signal that the output current control device is feedback with reference to the output current sensing apparatus, handle and an output direct current approximation, and according to this output direct current approximation, adjust the output current of this DC/AC switching device, make DC component contained in the output current level off to zero.

Aforesaid AC power supply device wherein further comprises: an output filter is to exchange the output that output line is connected in this DC/AC switching device by one.

Aforesaid AC power supply device, wherein DC power supply can be an independent DC power supply, direct-current generating device or through a direct current Blast Furnace Top Gas Recovery Turbine Unit (TRT) of AC/DC conversion.

Aforesaid AC power supply device, wherein the output current sensing apparatus is to be located to exchange on the output line.

Aforesaid AC power supply device, when wherein the output voltage of DC/AC switching device was not a direct current power positive end current potential or a direct current power supply negative terminal current potential, the output current of this DC/AC switching device of sensing also feedback that this outputs current to this output current control device.

Aforesaid AC power supply device is wherein handled and must this direct current approximation, and it carries out the start time point that calculates is number of cycles between putting with the concluding time.

Aforesaid AC power supply device, wherein the output current control device comprises an electronic type control unit and a power switch control unit.

The output current control method of AC power supply device of the present invention is:

A kind of output current control method of AC power supply device, it is characterized in that described AC power supply device comprises a DC/AC switching device, the output current sensing apparatus of this its output current of DC/AC switching device of one sensing, one is located at the output current control device between output current sensing apparatus and the DC/AC switching device, this control method comprises: sensing and an output current feedback signal, when the output current control device produced an output voltage stop signal and stops to export to control this DC/AC switching device, the output current of this this DC/AC switching device of output current sensing device senses was also feedback this output current feedback signal to this output current control device; Adjust output current, with the output current of described output current control device with reference to this output current sensing apparatus back coupling, handle and an output direct current approximation, and according to this output direct current approximation, adjust the output current of this DC/AC switching device, make DC component contained in the output current level off to zero.

The output current control method of aforesaid AC power supply device, wherein be when the output voltage of described DC/AC switching device is not a direct current power positive end current potential or a direct current power supply negative terminal current potential, sensing is also feedback described output current feedback signal to described output current control device.

The output current control method of aforesaid AC power supply device, wherein handle and an output direct current approximation, it carries out the start time point that calculates is number of cycles between putting with the concluding time.

The output current control method of aforesaid AC power supply device wherein before described output voltage stop signal begins, is adjusted the frequency of the output current of described DC/AC switching device, makes output current level off to zero accurate in advance.

The output current control method of aforesaid AC power supply device, wherein before described output voltage stop signal begins, adjust the frequency of the output current of described DC/AC switching device, make output current level off to zero accurate in advance, and when the output voltage stop signal finished, the initial value that makes output current was by zero accurate position beginning.

The invention has the beneficial effects as follows, and flip-flop in the output current can be controlled to be level off to zero.

Description of drawings

The present invention is further described below in conjunction with drawings and Examples.

Fig. 1 is a calcspar of the present invention.

Fig. 2 A is the inside calcspar of output current control device of the present invention.

Fig. 2 B is the detailed circuit diagram of power switch control unit one embodiment of the present invention.

Fig. 3 is the detailed circuit diagram of DC/AC switching device one embodiment of the present invention.

Fig. 4 is output voltage stop signal (V of the present invention _Stop) in an arbitrary period, each the main node signal waveforms when closing power switch.

Fig. 5 is that output voltage stop signal of the present invention is at output AC load voltage v _LOADDuring for positive edge zero crossover point, each the main node signal waveforms when closing power switch.

Fig. 6 is that output voltage stop signal of the present invention is at output AC load voltage v _LOADDuring for negative edge zero crossover point, each the main node signal waveforms when closing power switch.

Fig. 7 is output current sensing apparatus margin of error i of the present invention ₂₁* schematic diagram.

Fig. 8 is the schematic diagram that the present invention calculated and reduced the DC quantity in the output current.

Fig. 9 is the detailed circuit diagram of DC/AC switching device second embodiment of the present invention.

Figure 10 is the detailed circuit diagram of DC/AC switching device the 3rd embodiment of the present invention.

Figure 11 is the detailed circuit diagram of DC/AC switching device the 4th embodiment of the present invention.

Figure 12 is the detailed circuit diagram of DC/AC switching device the 5th embodiment of the present invention.

Figure 13 is output voltage stop signal (V of the present invention _Stop) the control mode oscillogram that cooperates output current to make zero in advance.

Figure 14 is output voltage stop signal (V of the present invention _Stop) another control mode oscillogram of cooperating output current to make zero in advance.

Figure 15 is the circuit diagram that Germany checks and approves No. 10249122 patent cases of bulletin DE.

The number in the figure explanation:

10 DC power supply

20 DC/AC switching devices

20a～20d DC/AC switching device

21 exchange output line

22,23 electric capacity

24,25 power switchs

26,27 diodes

30 output filters

40 AC load

50 output current sensing apparatus

60 output current control device

61 electronic type control units

62 power switch control units

Embodiment

See also shown in Figure 1ly, the calcspar for AC power supply device of the present invention system comprises:

One direct current power supply 10 can be independent DC power supply, the direct-current generating device of various types or the direct-current generating device of changing through AC/DC, can be in order to dc energy to be provided;

One DC/AC switching device 20 is the output that is coupled in this AC power 10, and the dc energy that DC power supply 10 is exported is converted to AC energy, and utilizes one to exchange output line 21 transmission AC energy;

One output filter 30 is via exchanging the output that output line 21 is connected to this DC/AC switching device 20;

One AC load 40 is the output that is coupled in output filter 30, and this AC load 40 can be the self AC load or the municipal power supply system of various types;

One output current sensing apparatus 50, be to be located between DC/AC switching device 20 and the output filter 30, for example can be located on this interchange output line 21, output current sensing apparatus 50 can correspondingly produce an output current feedback signal by the electric current that detecting exchanges on the output line 21, wherein, this output current sensing apparatus 50 can be the current sensing device of various types such as magnetic coupling mode, Hall coupled modes or resistor-type;

One output current control device 60, its input are to receive the output current feedback signal of being sent by output current sensing apparatus 50, and its output is to be connected to DC/AC switching device 20, is in order to adjust the electric current on this interchange output line 21.

See also shown in Fig. 2 A, be the inside calcspar of aforementioned output current control device 60, mainly comprise an electronic type control unit 61 and a power switch control unit 62.This electronic type control unit 61 can be made of a microprocessor, is to receive aforementioned output current feedback signal, and produces an output voltage control signal (V _Control) and an output voltage stop signal (V _Stop), two signals provide to power switch control unit 62.This output voltage control signal (V _Control) output current of adjustable DC/AC conversion apparatus 20 via power switch control unit 62, as for output voltage stop signal (V _Stop) then be to close power switch in the middle of the DC/AC switching device 20 by power switch control unit 62.

Internal structure about DC/AC switching device 20 1 embodiment sees also shown in Figure 3.DC/AC switching device 20 has two electric capacity 22,23 of connecting mutually, be in parallel two power switchs 24,25 of connecting mutually, wherein the series connection node of the series connection node of two series capacitances 22,23 and power switch 24,25 is the inputs that are connected to output filter 30 respectively, and the two ends of two power switchs 24,25 are diodes 26,27 in parallel separately.

See also shown in Fig. 2 B, be an embodiment of power switch control unit 62, this embodiment is DC/AC switching device 20 frameworks of corresponding diagram 3, so power switch control unit 62 mainly is to form with door assembly (2-input AND Gate) with two.Each has two inputs with door, wherein, two with the first input end of door be the two output voltage control signal (V that receive respectively from this electronic type control unit 61 _Control), two with second input of door be to receive aforementioned output voltage stop signal (V _Stop), two with the output of door then be to export two control signals respectively, with control respectively aforementioned two power switchs 24,25 by/conducting.

As shown in Figure 4, be output voltage stop signal (V _Stop) close 24,25 o'clock each point voltage oscillogram of power switch, from top to bottom, each waveform is represented following meaning respectively:

v _LOAD: be to provide the output voltage that gives AC load 40 by output filter 30.

V _Control: be output voltage control signal (V _Control) waveform.

V _Stop: be output voltage stop signal (V _Stop) waveform.

v ₂₄: be the control signal waveform of a power switch 24 wherein.

v ₂₅: be the control signal waveform of another power switch 25, with aforementioned control signal v ₂₄Both are complementary relationship.

v ₂₁: be measured output voltage waveforms on this interchange output line 21.

i ₂₁: be measured output current wave on this interchange output line 21.

This output voltage stop signal (V _Stop) can move in arbitrary time, and in case output voltage stop signal (V is arranged _Stop) exist, the output signal of this output current control device 60 will be ended, and is equal to the control signal v with power switch 24,25 ₂₄, v ₂₅Stop.

Output voltage stop signal (V _Stop) actual act comprise two period t ₂, t ₃At t ₂In period, the output current i of this DC/AC switching device 20 ₂₁Still non-vanishing, but because power switch 24,25 becomes open circuit, diode 26,27 and capacitor 22,23 form equivalent clamp circuit, the output voltage v of this DC/AC switching device 20 ₂₁Can force to transfer to a direct current power positive end current potential V _{01 (+)}An or direct current power supply negative terminal current potential V _{01 (-)}, and output current i ₂₁Can be compelled to gradually to zero.As output current i ₂₁After being compelled to discharge and being zero, be to enter t ₃Period, and output voltage v ₂₁In this t ₃Break away from clamp state in period, by judging output voltage v ₂₁Whether break away from clamp state, can differentiate output current i according to this ₂₁Whether be discharged to zero.

See also Fig. 5, shown in Figure 6, be output voltage stop signal (V _Stop) at output AC load voltage v _LOADDuring for positive edge and negative edge zero crossover point, close the each point voltage oscillogram of power switch 24,25.As output voltage stop signal (V _Stop) operate time when crossing over zero crossover point, its advantage is because of output voltage stop signal (V _Stop) institute causes output current i under the action ₂₁In harmonic content can effectively reduce.

Because at output current i ₂₁Actual when being zero, output current sensing apparatus 50 may still be assert the existence that output current is arranged, and the output current of being assert promptly is margin of error i ₂₁*.Therefore, as aforementioned, the present invention reads output voltage v ₂₁, and in output voltage stop signal (V _Stop) the action period in, with output voltage v ₂₁Non-strangulation is the positive terminal potential V of this DC power supply _{01 (+)}Or DC power supply negative terminal current potential V _{01 (-)}Be condition, as output current i ₂₁Be zero foundation, and so allowing to read the output current feedback signal under the situation, to obtain the margin of error i of this output current sensing apparatus 50 ₂₁*.

Please cooperate consult shown in Figure 7, for how obtaining aforementioned margin of error i ₂₁* waveform schematic diagram is because output voltage stop signal (V _Stop) effect, make that the power switch 24,25 in the DC/AC switching device 20 becomes open circuit, read the output current feedback signal of this output current sensing apparatus 50 this moment, promptly as this margin of error i ₂₁*.This margin of error i ₂₁* calculating can be reached by the detection area of island effect, be known that dynamic island effect detecting (Active anti-islandingmethod) can be reached by frequency disturbance method (Active frequency drift method), the introduction of relevant island effect can be consulted following two pieces of documents:

1.H.Kobayashi?et?al.，“Method?For?Preventing?IslandingPhenomenon?On?Utility?Grid?With?A?Number?of?Small?Scale?PVSystems，”22?IEEE?Photovoltaic?Specialists?Conference，Vol.1，pp.695-700，1991。

2.M.E.Ropp，M.Begovic，and?A.Rohatgi，“Analysis?andperformance?assessment?of?the?active?frequency?drift?method?ofislanding?prevention，”IEEE?Trans.on?Energy?Conversion，Vol.14，pp.810-816，1999。

Because margin of error i ₂₁Be to be output voltage stop signal (V when * capturing _Stop) working hour, so margin of error i ₂₁* represent output current i ₂₁The difference of its actual value and back coupling value is so if deduct margin of error i to measured output current feedback signal in the normal period ₂₁*, can obtain output current i ₂₁Actual value.

As shown in Figure 8, be that explanation utilizes this electric current output-controlling device 60 to calculate output current i ₂₁In DC quantity, and reduce the practice of DC quantity.In this example, be to calculate output current i in t (n-1)～t (n) zone ₂₁DC quantity, and in the zone of t (n)～t (n+1), reduce output current i ₂₁DC quantity.

I. in t (n-1)～t (n) zone, output current i ₂₁Actual DC amount i _{21 (DC)}Represented as following integral equation (1):

$i_{21\left(\mathrm{DC}\right)}=\underset{t(n-1)}{\overset{t\left(n\right)}{\∫}}\frac{i_{21}\left(t\right)}{t\left(n\right)-t(n-1)}\mathrm{dt}...\left(1\right)$

Margin of error i when the aforementioned output current sensing apparatus 50 of deduction ₂₁* after, Shi Ji DC quantity i then _{21 (DC)}To approach the direct current approximation i that following integral equation (2) is calculated _{21 (DC)}^.Wherein, i _{21_ (Feedback)}Be to reach by the output current feedback signal of aforementioned output current sensing apparatus 50.

$i_{21\left(\mathrm{DC}\right)}\≈{i_{21\left(\mathrm{DC}\right)}}^{^}\≡\underset{t(n-1)}{\overset{t\left(n\right)}{\∫}}\frac{i_{21\left(\mathrm{Feedback}\right)}-{i_{21}}^{*}}{t\left(n\right)-t(n-1)}\mathrm{dt}...\left(2\right)$

Wherein, output current control device 60 of the present invention calculates direct current approximation i _{21 (DC)}During ^, the start time point of carrying out the action that adds up in each calculating is to be number of cycles between putting with the concluding time, is number of cycles between t (n-1)～t (n) or t (n)～t (n+1) for example.

II. in the zone of t (n)～t (n+1), because actual DC quantity _{21 (DC)}Direct current approximation i _{21 (DC)}^ is calculated by equation (2), so can be according to this direct current approximation i _{21 (DC)}^ compensates the margin of error i of output current sensing apparatus 50 ₂₁*, with control output current i ₂₁The positive half cycle in the period of t (n)～t (n+1) and the mean value of negative half period make output current i ₂₁At t (the n)～DC quantity convergence of t (n+1) in the period is zero.Example output current i as shown in FIG. 8 ₂₁Its DC quantity is a negative value in the section of t (n-1)～t (n), represents output current i ₂₁Negative half period peak value i _{21-N (n-1)}Can be greater than positive half cycle peak value i _{21-P (n-1)}, therefore compensating the practice is to select to improve positive half cycle peak value i in the section of t (n)～t (n+1) _{21-P (n)}Or lower negative half period peak value i _{21-N (n)}

Fig. 9, Figure 10 are DC/AC switching device 20a, the 20b of two kinds of embodiment in addition, are based on DC/AC switching device shown in Figure 3 20 frameworks and revise, and these two kinds of embodiment can be applicable in the circuit of the present invention equally; And the DC/AC switching device 20c of Figure 11 is the change-over circuit of a three-phase four wire system, can be considered by three groups of single-phase AC to compose in parallel; The DC/AC switching device 20d of Figure 12 further extends with the three-phase and four-line framework of Figure 11 to become a three-phase three wire system.

See also shown in Figure 13ly, be amount of measurement error i of the present invention ₂₁* the another kind of feasible practice.At t1 in the period, load output voltage v _LOADBe output current i with DC/AC switching device 20 ₂₁Same same frequency, and at output voltage stop signal (V _Stop) before the beginning, conveniently improve output current i slightly with output current control device 60 ₂₁Frequency, promptly at present shown in the drawing between t ₁*, make output current i ₂₁Can be than load output voltage v _LOADFaster near zero accurate position, so this output voltage stop signal (V _Stop) when beginning, at t ₂Output current i in period ₂₁Quite micro-, in entering t ₃The time, then be that to finish entirely be zero accurate position.Thus, as this output voltage stop signal (V _Stop) when finishing, output current i ₂₁Initial value will can be not excessive, so at amount of measurement error i ₂₁* the time, output current i ₂₁In harmonic components also more can not form too big influence to measurement result.

Shown in Figure 14 then is another kind of margin of error i ₂₁* the measurement practice, similar with the practice of aforementioned Figure 13, also be to adjust output current i ₂₁Frequency.Specifically, output voltage stop signal (V _Stop) be that design is at load output voltage v _LOADNegative edge zero crossover point on, at this load output voltage v _LOADThere is load output voltage v _LOADComplete cycle in, be to adjust output current i ₂₁Frequency, make the time (t of its half period ₁*) than the time (t of original half period ₁) shorter, thus, output current i ₂₁To comparatively fast level off to zero accurate, so in case output voltage stop signal (V _Stop) when beginning, need only want extremely short t transit time ₂Just can enter the state of zero accurate position, i.e. t fully ₃Time, and at output voltage stop signal (V _Stop) moment of stopping, this output current i ₂₁Initial value will be by zero accurate position beginning, thus, output current i ₂₁In harmonic components can effectively suppress, make margin of error i ₂₁* measurement can be more accurate.

Aforementioned calculation method only is an embodiment, other existing operation method, as weighted mean method (Weighted Average Method), the method for moving average (Moving Average Method) and moving weighted average method (Moving Weighted Average Method) etc., also can be used to calculating and obtain this direct current approximation.

Therefore in sum, when utilizing the present invention to control the output current of AC power supply device, must additionally not use bulky transformer or ac capacitor, with regard to the volume of AC power supply device integral body and manufacturing cost and Yan Junyou significantly improves; Moreover general current sensing device all has the unfixed margin of error, and the common practice can directly be treated as margin of error deduction with the current value of feedbacking earlier before starting DC/AC switching device; But this practice is after whole AC power supply device operationalizes, because the interference of factors such as temperature, magnetic field, the actual error amount is different with the margin of error that initially obtains usually, and the result makes the DC quantity of output current to be adjusted effectively and levels off to zero.But the present invention's dynamic real-time calculates the DC quantity approximation that is contained in the general ac output current, and with reference to this DC quantity approximation suitably adjust exchange in the output just/negative half period, make the flip-flop in the whole ac output current can effectively level off to zero, to provide quality better alternating electromotive force.

The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, every foundation technical spirit of the present invention all still belongs in the scope of technical solution of the present invention any simple modification, equivalent variations and modification that above embodiment did.

Claims (12)

1. an AC power supply device is characterized in that, comprising:

One direct current power supply provides DC power supply;

One DC/AC switching device, the conversion DC power supply is an AC power;

One output current sensing apparatus is detected the output current of this DC/AC switching device, and produces an output current feedback signal according to this;

One output current control device receives aforementioned output current feedback signal and controls this DC/AC switching device;

Wherein, when the output current control device produces an output voltage stop signal and stops to export to control this DC/AC switching device, the output current feedback signal that the output current control device is feedback with reference to the output current sensing apparatus, handle and an output direct current approximation, and according to this output direct current approximation, adjust the output current of this DC/AC switching device, make DC component contained in the output current level off to zero.

2. AC power supply device according to claim 1 is characterized in that further comprising:

One output filter is to exchange the output that output line is connected in this DC/AC switching device by one.

3. AC power supply device according to claim 1 is characterized in that the direct current Blast Furnace Top Gas Recovery Turbine Unit (TRT) that described DC power supply can be an independent DC power supply, direct-current generating device or changes through AC/DC.

4. AC power supply device according to claim 2 is characterized in that described output current sensing apparatus is to be located to exchange on the output line.

5. AC power supply device according to claim 1, when the output voltage that it is characterized in that described DC/AC switching device was not a direct current power positive end current potential or a direct current power supply negative terminal current potential, the output current of this DC/AC switching device of sensing also feedback that this outputs current to this output current control device.

6. AC power supply device according to claim 1 is characterized in that described processing and must this output direct current approximation, and it carries out the start time point that calculates is number of cycles between putting with the concluding time.

7. AC power supply device according to claim 1 is characterized in that described output current control device comprises an electronic type control unit and a power switch control unit.

8. the output current control method of an AC power supply device, it is characterized in that described AC power supply device comprises that the output current sensing apparatus, of a DC/AC switching device, this its output current of DC/AC switching device of a sensing is located at the output current control device between output current sensing apparatus and the DC/AC switching device, this control method comprises:

Sensing and an output current feedback signal, when the output current control device produced an output voltage stop signal and stops to export to control this DC/AC switching device, the output current of this this DC/AC switching device of output current sensing device senses was also feedback this output current feedback signal to this output current control device;

Adjust output current, with the output current of described output current control device with reference to this output current sensing apparatus back coupling, handle and an output direct current approximation, and according to this output direct current approximation, adjust the output current of this DC/AC switching device, make DC component contained in the output current level off to zero.

9. the output current control method of AC power supply device according to claim 8, it is characterized in that it being when the output voltage of described DC/AC switching device is not a direct current power positive end current potential or a direct current power supply negative terminal current potential, sensing is also feedback described output current feedback signal to described output current control device.

10. the output current control method of AC power supply device according to claim 8, it is characterized in that described processing and an output direct current approximation, it carries out the start time point that calculates is number of cycles between putting with the concluding time.

11. the output current control method of AC power supply device according to claim 8, it is characterized in that before described output voltage stop signal begins, adjust the frequency of the output current of described DC/AC switching device, make output current level off to zero accurate in advance.

12. the output current control method of AC power supply device according to claim 8, it is characterized in that before described output voltage stop signal begins, adjust the frequency of the output current of described DC/AC switching device, make output current level off to zero accurate in advance, and when the output voltage stop signal finished, the initial value that makes output current was by zero accurate position beginning.

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