CN107834883A - A kind of mid-point voltage control device and method based on modulating wave interval division - Google Patents
A kind of mid-point voltage control device and method based on modulating wave interval division Download PDFInfo
- Publication number
- CN107834883A CN107834883A CN201711023190.9A CN201711023190A CN107834883A CN 107834883 A CN107834883 A CN 107834883A CN 201711023190 A CN201711023190 A CN 201711023190A CN 107834883 A CN107834883 A CN 107834883A
- Authority
- CN
- China
- Prior art keywords
- zero
- modulation wave
- phase
- interval
- sequence component
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- 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
- H02M1/14—Arrangements for reducing ripples from dc input or output
-
- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention discloses a kind of mid-point voltage control device and method based on modulating wave interval division.The device includes three-level inverter, digital processing control module and drive circuit, and wherein digital processing control module includes sampling unit, Closed Loop Control Unit, sinusoidal pulse width modulation unit, modulating wave interval division unit and zero-sequence component computing unit.Method is：Calculate the deviation angle that three-phase modulations signal adds zero crossing after zero-sequence component；Modulating wave section is divided, and calculates and suppresses the required zero-sequence component of mid-point voltage fluctuation；By comparing the instantaneous voltage of electric capacity above and below DC side, the symbol of zero-sequence component is judged；Adjust signal to be added with three-phase zero-sequence component, and pass through sinusoidal pulse width modulation cell processing, obtain pulse-width modulation control signal, and then drive circuit control three-level inverter switching tube work.Hardware cost of the present invention is low, precise control, applied widely, can effectively suppress mid-point voltage fluctuation, reduces the aberration rate of networking electric current.
Description
Technical Field
The invention belongs to the technical field of control in power electronic conversion technology, and particularly relates to a midpoint voltage control device and method based on modulation wave interval division.
Background
The NPC three-level inverter has the advantages of mature topological structure, low bearing voltage of a switching device, low output harmonic content and the like, and is widely applied to medium and high power occasions. However, due to the inherent characteristics of the NPC three-level inverter, the dc side of the inverter has a problem of midpoint voltage fluctuation. At present, three solutions are mainly used for solving the problem of neutral point voltage fluctuation on the direct current side of the three-level inverter: (1) An independent direct current voltage source is adopted to supply power to a direct current side capacitor; (2) an external midpoint balance control circuit; (3) adopting a specific midpoint voltage control method; the first two methods are generally not considered because they increase hardware costs.
Under ideal grid conditions, the existing midpoint voltage control method is relatively mature, such as a DPWM method based on zero sequence component injection, an SVPWM method based on redundant small vector adjustment, a method based on hybrid modulation, and the like. However, in actual conditions, a grid fault can cause unbalance of three-phase voltages on a grid side, the amplitude of the midpoint voltage fluctuation can be increased in a state of unbalance of the three-phase voltages, the frequency is changed from three times of power frequency in the three-phase balance to power frequency, and odd harmonic components of 3, 5, 7 and the like are contained, so that difficulty is brought to control of the midpoint voltage.
Disclosure of Invention
The invention aims to provide a midpoint voltage control method and device based on modulation wave interval division and suitable for non-ideal power grid conditions, which can realize the balance of upper and lower capacitor voltages on the DC side of an inverter under the non-ideal power grid conditions and have better effect under the condition of low-power factor operation.
The technical solution for realizing the purpose of the invention is as follows: a midpoint voltage control device based on modulation wave interval division comprises a three-level inverter, a digital processing control module and a driving circuit, wherein:
the digital processing control module comprises a sampling unit, a closed-loop control unit, a sine pulse width modulation unit, a modulation wave interval division unit and a zero-sequence component calculation unit; the sampling unit respectively collects an upper capacitor voltage signal and a lower capacitor voltage signal on the direct current side of the three-level inverter, a three-phase voltage signal on the alternating current side of the three-level inverter and a three-phase current signal on the alternating current side of the three-level inverter and sends the three-phase voltage signals to the modulation wave interval division unit, the zero-sequence component calculation unit and the closed-loop control unit; the modulation wave interval division unit and the zero sequence component calculation unit calculate a zero sequence component required for inhibiting the midpoint voltage fluctuation according to the alternating current side current signal and the modulation wave signal obtained by sampling, the zero sequence component and the modulation wave signal obtained by the closed-loop control unit are added and sent to the sine pulse width modulation unit, and the output end of the sine pulse width modulation unit is connected to each switching tube of each phase of bridge arm in the three-level inverter through a driving circuit.
A midpoint voltage control method based on modulation wave interval division comprises the following steps:
step 1, sampling three-phase voltage e at alternating current side a 、e b 、e c Alternating side three-phase current i a 、i b 、i c Capacitor voltage U on the DC side C1 Lower capacitor voltage U on the DC side C2 ；
Step 2, utilizing a symmetrical component method to carry out three-phase voltage e on the alternating current side a 、e b 、e c And three-phase current i on alternating current side a 、i b 、i c Performing positive and negative sequence decomposition;
step 3, calculating current set by taking the elimination of active power fluctuation as a target, and obtaining a three-phase modulation wave u through a closed-loop control unit a 、u b 、u c ；
Step 4, calculating the zero crossing point offset angle of the a, b and c three-phase modulation wave after adding the zero sequence component
Step 5, dividing a power frequency cycle into six modulation wave intervals by using the zero crossing point offset angle of the three-phase modulation wave obtained in the step 4, wherein the six modulation wave intervals are respectively as follows:
interval i:
and an interval II:
interval iii:
interval iv:
interval v:
interval VI:
wherein the content of the first and second substances,is the zero crossing point of the modulation wave before adding the zero sequence component;
step 6, calculating zero sequence component u in each interval by using the six modulation wave intervals divided in the step 5 0 ；
And 7, comparing the instantaneous voltages of the upper capacitor and the lower capacitor on the direct current side:
when U is turned C1 >U C2 When the method is used:
u′ 0 ＝-|u 0 |
when U is turned C1 <U C2 When the method is used:
u′ 0 ＝|u 0 |
wherein u' 0 The zero sequence component is finally added with the three-phase modulation wave;
and 8, generating a pulse width modulation signal by the three-phase modulation signal through a sine pulse width modulation unit, and controlling the work of a switching tube of the three-level inverter by a driving circuit.
Compared with the prior art, the invention has the remarkable advantages that: (1) The accurate zero sequence component is directly calculated by dividing the regions, which is beneficial to the real-time control of the midpoint voltage; (2) The distortion rate of the output current is reduced, and the waveform quality is improved.
Drawings
Fig. 1 is a schematic structural diagram of a midpoint voltage control device based on modulation wave interval division according to the present invention.
Fig. 2 is a schematic diagram of a modulation wave offset angle in a modulation wave interval division-based midpoint voltage control method of the invention.
Fig. 3 is a division diagram of the angle interval of the modulation wave in one cycle in the invention.
Fig. 4 is a topology diagram of an NPC three-level grid-connected inverter.
Fig. 5 is a flow chart of zero sequence component calculation in the present invention.
Fig. 6 is a graph of waveforms of upper and lower capacitors on the dc side before and after the control method of the present invention is added to 0.1s at a power factor of 1.
Fig. 7 is a graph of waveforms of upper and lower capacitors on the dc side before and after the control method of the present invention is added at 0.1s when the power factor is 0.866.
Fig. 8 is a graph of the waveforms of the upper and lower capacitors on the dc side before and after the control method of the present invention is added at 0.1s for a power factor of 0.5.
Fig. 9 is a comparison graph of the grid-side current harmonic distribution before and after the control method of the present invention is added, where (a) is the grid-side current harmonic distribution before the control method of the present invention is added, and (b) is the grid-side current harmonic distribution after the control method of the present invention is added.
Detailed Description
With reference to fig. 1, a midpoint voltage control device based on modulated wave interval division includes a three-level inverter, a digital processing control module and a driving circuit, wherein the digital processing control module includes a sampling unit, a closed-loop control unit, a sine pulse width modulation unit, a modulated wave interval division unit and a zero-sequence component calculation unit; the sampling unit respectively collects an upper capacitor voltage signal and a lower capacitor voltage signal on the direct current side of the three-level inverter, a three-phase voltage signal on the alternating current side of the three-level inverter and a three-phase current signal on the alternating current side of the three-level inverter and sends the three-phase voltage signal and the three-phase current signal to the modulated wave interval division unit, the zero-sequence component calculation unit and the closed-loop control unit, the modulated wave interval division unit and the zero-sequence component calculation unit calculate a zero-sequence component required for inhibiting midpoint voltage fluctuation according to the alternating current side current signal and the modulated wave signal obtained by sampling, the zero-sequence component and the modulated wave signal obtained by the closed-loop control unit are added and sent to the sine pulse width modulation unit, and the output end of the sine pulse width modulation unit is connected to each switching tube of each phase bridge arm in the three-level inverter through a driving circuit.
As a specific example, the digital processing control modules are TMS320F28335 and EPM1270T chips.
A midpoint voltage control method based on modulation wave interval division specifically comprises the following steps:
step 1, in each switching period, a sampling unit of a digital processing control module respectively samples voltage e at an alternating current side a 、e b 、e c Alternating side current i a 、i b 、i c Capacitor voltage U on the DC side C1 The capacitor voltage U under the DC side C2 ；
Step 2, utilizing a symmetrical component method to carry out voltage e on the alternating current side a 、e b 、e c AC side current i a 、i b 、i c The positive and negative sequence decomposition is performed because the NPC three-level inverter in the present embodiment adopts a three-phase three-wire system connection method, so the network side is not consideredThe zero sequence components of the voltage and the current are only considered, and the positive sequence components and the negative sequence components are only considered;
step 3, calculating current set by taking the elimination of active power fluctuation as a target, and obtaining a three-phase modulation wave u through a closed-loop control unit a 、u b 、u c The method comprises the following steps:
step 3.1, putting the three-phase stationary coordinate system under e a 、e b 、e c 、i a 、i b 、i c The positive and negative sequence alternating current quantities are converted into direct current quantities under a positive and negative sequence synchronous rotating coordinate system, and the conversion matrixes of the positive and negative sequence synchronous rotating coordinate system are respectively as follows:
obtaining d and q axis components e of the voltage and the current under the positive sequence synchronous rotating coordinate system through conversion dp 、e qp 、i dp 、i qp And d and q axis components e of voltage and current under negative sequence synchronous rotation coordinate system dn 、e qn 、i dn 、i qn ；
Step 3.2, under the condition of a non-ideal power grid, the active and reactive instantaneous power of the inverter can contain fluctuation quantity of twice power frequency, and according to the instantaneous reactive power theory, the direct current quantity and the fluctuation quantity in the instantaneous power are as follows:
wherein i * dp Given for the current of the positive sequence d-axis, i * qp Given the current of the positive sequence q-axis, i * dn Given the current of the negative sequence d-axis, i * qn Given for negative sequence q-axis current, P 0 Is instantaneously activeDirect current component of power, P c2 、P s2 Being an alternating component of instantaneous active power, Q 0 Being the direct component of instantaneous reactive power, Q c2 、Q s2 Is an alternating current component of instantaneous reactive power, and when the control target is to eliminate the fluctuation amount P of active power c2 、P s2 Then, the expression given for the current can be obtained:
wherein E is 1 、E 2 The expression of (a) is:
step 3.3, obtaining 4 paths of modulation wave signals u under the synchronous rotating coordinate system through a closed-loop control unit dp 、u qp 、u dn 、u qn The control equation is as follows:
step 3.4, firstly, modulating wave signal u under negative sequence two-phase rotating coordinate system dn 、u qn Converting the negative sequence component under the three-phase static coordinate system into a positive sequence synchronous rotating coordinate system, wherein the conversion matrixes are respectively as follows:
obtaining negative sequence component under positive sequence rotating coordinate system through conversion, adding positive and negative sequence modulated wave components under the same coordinate system to obtain modulated wave component u under positive sequence synchronous rotating coordinate system d 、u q ；
Step 3.5, converting the modulation wave signal under the synchronous rotating coordinate system into a three-phase modulation wave signal u a 、u b 、u c The conversion formula is as follows:
step 4, in order to suppress the fluctuation of the neutral point voltage at the direct current side of the inverter, injecting a zero sequence component into the three-phase modulation wave to make the neutral point current at the direct current side zero, thereby suppressing the fluctuation of the neutral point voltage at the direct current side, and obtaining a calculation formula of the zero sequence component as follows:
wherein u' a 、u' b 、u' c For three-phase modulated waves, u, after the addition of zero-sequence components ap 、u bp 、u cp Is a positive sequence component of a three-phase modulated wave, u an 、u bn 、u cn Being the negative-sequence component of a three-phase modulated wave, i ap 、i bp 、i cp Is a positive sequence component of the three-phase current on the network side, i an 、i bn 、i cn Is the negative sequence component of the three-phase current on the grid side, and u is known from the above formula 0 U 'needs to be judged for solution' a 、u' b 、u' c Symbol of (1), and u' a 、u' b 、u' c Containing u to be solved 0 Therefore, the zero sequence component cannot be directly obtained by the above formula.
As shown in FIG. 2, after adding zero sequence component, the zero crossing point of the modulated wave will produce an angle offset, and it is known that the three-phase modulated wave u without adding zero sequence component a 、u b 、u c U 'can be determined by calculating respective zero-crossing offset angles of the three-phase modulated waves after adding the zero-sequence component' a 、u' b 、u' c And calculating to obtain the zero sequence component required for inhibiting the midpoint voltage fluctuation.
The modulation wave interval division unit calculates a zero-crossing point offset angle of an x-phase modulation wave after zero-sequence components are added, the x-phase represents any one of a phase a, a phase b and a phase c, and the zero-crossing point offset angle has the expression:
in the above formula, the first and second carbon atoms are,for the x-phase modulation wave offset angle,for minimum zero crossing of x-phase modulated wave, u z For dividing intervals by three-phase modulating wave symbols to obtain zero-sequence component u z The expression of (a) is as follows:
and 5, with reference to fig. 3, dividing a power frequency cycle into six modulated wave intervals by using the offset angle of the three-phase modulated wave obtained in the step (4), wherein the six modulated wave intervals are respectively as follows:
interval i:
and an interval II:
interval iii:
interval iv:
interval v:
interval VI:
step 6, utilizing the six modulation wave intervals divided in the step 5, the zero sequence component calculating unit respectively calculates the zero sequence component u in each interval 0 The expression is as follows:
when ω t is located in interval I:
when ω t is located in interval II:
when ω t is located in interval iii:
when ω t is located in interval iv:
when ω t is located in interval V:
when ω t is located in interval vi:
wherein u ap 、u bp 、u cp Is a positive sequence component of a three-phase modulated wave, u ap 、u bp 、u cp Is a negative sequence component of a three-phase modulated wave, i ap 、i bp 、i cp Is a positive sequence component of the three-phase current on the network side, i ap 、i bp 、i cp Is the negative sequence component of the three-phase current on the grid side.
And 7, comparing the instantaneous voltages of the upper capacitor and the lower capacitor on the direct current side:
when U is turned C1 >U C2 The method comprises the following steps:
u′ 0 ＝-|u 0 |
when U is turned C1 <U C2 The method comprises the following steps:
u′ 0 ＝|u 0 |
wherein, u' 0 The zero sequence component is finally added with the three-phase modulation wave;
step 8, zero sequence component u 0 Respectively associated with three-phase modulated waves u a 、u b 、u c Adding to obtain:
u′ a ＝u a +u′ 0
u′ b ＝u b +u′ 0
u′ b ＝u b +u′ 0
adding the modulated wave signal u 'after the zero sequence component is added' a 、u' b 、u' c And the pulse width modulation signals are sent to a sine pulse width modulation unit to generate pulse width modulation signals, and a driving circuit controls the work of a switching tube of the three-level inverter to realize the control of midpoint voltage balance.
The modulation rule of the NPC three-phase three-level inverter is as follows: as shown in FIG. 4, taking the a-phase bridge arm as an example, in u aref Positive half cycle of (d), when u aref When greater than the carrier, order S a1 、S a2 When the a-phase bridge arm is conducted, the a-phase bridge arm outputs high level when u is aref When smaller than the carrier wave, order S a2 、S a3 Conducting, and outputting zero level by the a-phase bridge arm; at u aref Negative half cycle of (d), when u aref When smaller than the carrier, order S a3 、S a4 When the a-phase bridge arm outputs low level, when u aref When greater than the carrier, order S a2 、S a3 And when the bridge arm is switched on, the a-phase bridge arm outputs zero level. b. The modulation rules of the c-phase bridge arms are the same.
Fig. 5 is a flowchart of calculating a zero sequence component, and the specific implementation process is as follows:
s1, sampling three-phase current signals of a network side;
s2, detecting the modulation wave of the current power frequency periodZero crossing angle
S3, setting a maximum allowable error angleJudging the zero crossing angle of the modulation wave in the current power frequency cycleThe zero crossing angle of the modulated wave in the last power frequency periodSize of (1), ifThe division condition of the modulation wave interval of the kth power frequency period is consistent with that of the kth-1 power frequency period, the zero sequence component is calculated, S1 is skipped, and the cycle of the next power frequency period is entered; if it isCalculating the zero crossing point offset angle of the modulation wave in the current power frequency period, dividing the modulation wave interval, calculating the zero sequence component, jumping to S1, and entering the cycle of the next power frequency period.
Example 1
In the embodiment, a three-level inverter circuit is built by using a Simulink tool in MATLAB, and after direct current passes through a direct current bus capacitor, three-level inverter circuit inverts to output three-phase voltage and outputs smooth three-phase sinusoidal voltage through an LC filter circuit. The electrical parameter settings during the simulation are as in table 1:
TABLE 1
FIG. 6 shows the electrical parametersDC bus capacitor C when power factor of lower inverter network side is 1 1 、C 2 Instantaneous voltage U c1 、U c2 The control method of the invention is added at the time of 0.1 s. The instantaneous voltage of the upper and lower capacitors on the dc side has a voltage fluctuation of about 20V in magnitude before the control method of the present invention is not added, and the fluctuation of the voltage of the upper and lower capacitors on the dc side is limited to within 2V after the control method of the present invention is added. Fig. 7 and 8 respectively show the dc bus capacitor C when the power factor of the inverter network side is 0.866 and 0.5 1 、C 2 Instantaneous voltage U c1 、U c2 The simulation waveform of (2) is unchanged, other conditions are unchanged, the control method provided by the invention is added at the time of 0.1s, and the fluctuation of the upper and lower capacitor voltages on the direct current side is limited within 2V. It can be seen that the control method of the present invention still has a desirable effect under low power factor. Fig. 9 (a) and (b) show the net side current total harmonic distortion before and after the midpoint control method is added, and it can be seen that the midpoint control method of the present invention effectively suppresses odd harmonics such as 3, 5, 7, and 9 in the net side current, and reduces the total harmonic distortion of the current.
In summary, the midpoint voltage control method based on modulation wave interval division divides the modulation wave signal into intervals by calculating the offset angle of the zero crossing point of the three-phase modulation wave, and calculates the zero sequence component required for inhibiting the midpoint voltage fluctuation according to the interval and the difference value of the instantaneous voltages of the upper capacitor and the lower capacitor on the direct current side. And respectively adding the zero-sequence component and the three-phase modulation wave, carrying out amplitude limiting, generating a pulse width modulation signal through a sinusoidal pulse width modulation unit, and driving a circuit by the pulse width modulation signal to control a switching tube of the three-level inverter to work so as to realize control of neutral point voltage balance. The invention directly calculates the accurate zero sequence component by dividing the interval again without correcting the zero sequence component, reduces the harmonic wave of the output voltage and current, improves the waveform quality, has better control effect under the condition of low-power factor operation of the inverter, is beneficial to the grid-connected inverter to transmit the reactive power to the network side, and has great engineering application value.
Claims (6)
1. A midpoint voltage control device based on modulation wave interval division is characterized by comprising a three-level inverter, a digital processing control module and a driving circuit, wherein:
the digital processing control module comprises a sampling unit, a closed-loop control unit, a sine pulse width modulation unit, a modulation wave interval division unit and a zero-sequence component calculation unit; the sampling unit respectively collects an upper capacitor voltage signal and a lower capacitor voltage signal on the direct current side of the three-level inverter, a three-phase voltage signal on the alternating current side of the three-level inverter and a three-phase current signal on the alternating current side of the three-level inverter and sends the three-phase voltage signals to the modulation wave interval division unit, the zero-sequence component calculation unit and the closed-loop control unit; the modulation wave interval division unit and the zero sequence component calculation unit calculate a zero sequence component required for inhibiting the midpoint voltage fluctuation according to the alternating current side current signal and the modulation wave signal obtained by sampling, the zero sequence component and the modulation wave signal obtained by the closed-loop control unit are added and sent to the sine pulse width modulation unit, and the output end of the sine pulse width modulation unit is connected to each switching tube of each phase of bridge arm in the three-level inverter through a driving circuit.
2. The modulation wave interval division-based midpoint voltage control device according to claim 1, wherein the digital processing control modules are TMS320F28335 and EPM1270T chips.
3. A midpoint voltage control method based on modulation wave interval division is characterized by comprising the following steps:
step 1, sampling three-phase voltage e at alternating current side a 、e b 、e c Alternating side three-phase current i a 、i b 、i c Capacitor voltage U on the DC side C1 Lower capacitor voltage U on the DC side C2 ；
Step 2, utilizing a symmetrical component method to carry out three-phase voltage e on the alternating current side a 、e b 、e c Three-phase current i on alternating current side a 、i b 、i c Performing positive and negative sequence decomposition;
step 3, calculating current set by taking the elimination of active power fluctuation as a target, and obtaining a three-phase modulation wave u through a closed-loop control unit a 、u b 、u c ；
Step 4, calculating the zero crossing point offset angle of the a, b and c three-phase modulation wave after adding the zero sequence component
Step 5, dividing a power frequency cycle into six modulation wave intervals by using the zero crossing point offset angle of the three-phase modulation wave obtained in the step 4, wherein the six modulation wave intervals are respectively as follows:
the interval I:
and an interval II:
interval iii:
interval iv:
interval v:
interval vi:
wherein the content of the first and second substances,is the zero crossing point of the modulation wave before adding the zero sequence component;
step 6, calculating zero sequence component u in each interval by using the six modulation wave intervals divided in the step 5 0 ；
And 7, comparing the instantaneous voltages of the upper capacitor and the lower capacitor on the direct current side:
when U is turned C1 >U C2 The method comprises the following steps:
u′ 0 ＝-|u 0 |
when U is formed C1 <U C2 The method comprises the following steps:
u′ 0 ＝|u 0 |
wherein u' 0 Zero sequence component added with three-phase modulation wave finally;
and 8, generating a pulse width modulation signal by the three-phase modulation signal through a sine pulse width modulation unit, and controlling the work of a switching tube of the three-level inverter by a driving circuit.
4. The modulation wave interval division-based midpoint voltage control method according to claim 3, wherein the step 4 calculates the zero-crossing point offset angle of the a, b, c three-phase modulation wave after adding the zero-sequence componentThe method comprises the following specific steps:
let x represent any one of a, b, and c phases, and the zero-crossing point offset angle is expressed as:
in the formula (I), the compound is shown in the specification,the zero-crossing point of the x-phase modulation wave is offset by an angle,for minimum zero crossing of x-phase modulated wave, u z Dividing the three-phase modulated wave symbol into regions to calculate zero sequenceComponent u z The expression of (c) is as follows:
。
5. the midpoint voltage control method based on the division of the modulated wave intervals according to claim 3, wherein the step 5 of dividing one power frequency cycle into six modulated wave intervals comprises the following specific steps:
s1, sampling three-phase current signals of a network side;
s2, detecting the zero crossing angle of the modulation wave of the current power frequency cycle
S3, setting a maximum allowable error angleJudging the zero crossing angle of the modulation wave in the current power frequency cycleZero crossing angle of modulation wave in previous power frequency periodSize of (1), ifThe division condition of the modulation wave interval of the kth power frequency period is consistent with that of the kth-1 power frequency period, and the modulation wave interval is jumped to S1 to enter the cycle of the next power frequency period; if it isCalculating the zero crossing point offset angle of the modulation wave in the current power frequency period, dividing the modulation wave interval, jumping to S1, and entering the cycle of the next power frequency period.
6. The modulation wave interval division-based midpoint voltage control method according to claim 3, wherein step 6 calculates the zero-sequence component u in each of the six modulation wave intervals divided in step 5 by using the six modulation wave intervals divided in step 5 0 The expression is as follows:
when ω t is located in interval I:
when ω t is located in interval II:
when ω t is located in interval iii:
when ω t is located in interval iv:
when ω t is located in interval v:
when ω t is located in interval vi:
wherein u ap 、u bp 、u cp Is a positive sequence component of a three-phase modulated wave, u ap 、u bp 、u cp Is a negative sequence component of a three-phase modulated wave, i ap 、i bp 、i cp Is a positive sequence component of the three-phase current on the network side, i ap 、i bp 、i cp Is the negative sequence component of the three-phase current on the grid side.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711023190.9A CN107834883B (en) | 2017-10-27 | 2017-10-27 | Midpoint voltage control device based on modulation wave interval division |
| CN201910921321.8A CN110707958B (en) | 2017-10-27 | 2017-10-27 | Modulation wave interval division-based midpoint voltage control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711023190.9A CN107834883B (en) | 2017-10-27 | 2017-10-27 | Midpoint voltage control device based on modulation wave interval division |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910921321.8A Division CN110707958B (en) | 2017-10-27 | 2017-10-27 | Modulation wave interval division-based midpoint voltage control method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107834883A true CN107834883A (en) | 2018-03-23 |
| CN107834883B CN107834883B (en) | 2020-06-19 |
Family
ID=61649739
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910921321.8A Active CN110707958B (en) | 2017-10-27 | 2017-10-27 | Modulation wave interval division-based midpoint voltage control method |
| CN201711023190.9A Active CN107834883B (en) | 2017-10-27 | 2017-10-27 | Midpoint voltage control device based on modulation wave interval division |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910921321.8A Active CN110707958B (en) | 2017-10-27 | 2017-10-27 | Modulation wave interval division-based midpoint voltage control method |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN110707958B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108306536A (en) * | 2018-04-20 | 2018-07-20 | 西安科技大学 | A kind of NPC three-level inverters of SPWM modulation |
| CN108880297A (en) * | 2018-06-29 | 2018-11-23 | 南京理工大学 | A kind of phase compensation device and method based on Vienna rectifier |
| CN109347354A (en) * | 2018-11-26 | 2019-02-15 | 合肥科威尔电源系统有限公司 | Mid-point voltage Ripple Suppression device and method based on third-harmonic zero-sequence voltage |
| CN109951093A (en) * | 2019-03-13 | 2019-06-28 | 南京理工大学 | A kind of mid-point voltage control system and method based on hybrid parameter |
| CN110011322A (en) * | 2019-04-17 | 2019-07-12 | 山东大学 | Diode clamping tri-level inverter hybrid passive control system and method under the conditions of low voltage crossing |
| CN110581663A (en) * | 2019-10-16 | 2019-12-17 | 南京理工大学 | Phase compensation device and method of Vienna rectifier under low carrier ratio |
| CN111342690A (en) * | 2020-03-13 | 2020-06-26 | 南京理工大学 | Split capacitor power unit multilevel converter and modulation strategy thereof |
| CN114421837A (en) * | 2021-08-31 | 2022-04-29 | 宁波诺丁汉大学 | Discontinuous pulse width modulation algorithm with adaptive power factor |
| CN115459553A (en) * | 2022-09-16 | 2022-12-09 | 山东艾诺仪器有限公司 | Method for controlling midpoint potential spwm of t-type three-level pwm rectifier |
| WO2024120381A1 (en) * | 2022-12-08 | 2024-06-13 | 青岛海信日立空调系统有限公司 | Power source apparatus and control method therefor |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114583989B (en) * | 2021-03-22 | 2023-09-22 | 上海正泰电源系统有限公司 | Three-level inverter modulation mode switching method, device, equipment and storage medium |
| CN112928777B (en) * | 2021-03-22 | 2023-12-19 | 阳光电源股份有限公司 | Cascaded grid-connected inverter control method and device |
| CN114244229B (en) * | 2021-12-22 | 2024-02-27 | 北京国家新能源汽车技术创新中心有限公司 | Motor control method, motor, vehicle, storage medium and computer |
| CN116706927B (en) * | 2023-08-08 | 2023-10-13 | 南京理工大学 | Computing method for optimal voltage support reference current of four-bridge arm inverter |
| CN118017818A (en) * | 2024-04-09 | 2024-05-10 | 湖南大学 | Three-level fault tolerance oriented voltage ripple suppression circuit, control device and method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5349522A (en) * | 1991-06-14 | 1994-09-20 | Hitachi, Ltd. | Method and apparatus for controlling the output voltage of an AC electrical system |
| CN101753044A (en) * | 2010-01-26 | 2010-06-23 | 北方工业大学 | Three-level midpoint potential balance control method based on zero-sequence voltage injection |
| CN104836464A (en) * | 2015-05-26 | 2015-08-12 | 东南大学 | Neutral-point-potential balance control device and method for direct current side of VIENNA rectifier |
| CN105305863A (en) * | 2015-10-10 | 2016-02-03 | 天津大学 | Point potential balance control method in three-level NPC inverter |
| CN106100402A (en) * | 2016-07-07 | 2016-11-09 | 西安理工大学 | A kind of T-shaped three-level inverter and neutral balance control method thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103973088B (en) * | 2014-05-22 | 2017-01-04 | 中国南方电网有限责任公司电网技术研究中心 | Balance of voltage method between multi-level inverter bridge arm based on peak value prediction |
| CN104052323B (en) * | 2014-07-02 | 2017-08-04 | 南京理工大学 | Neutral-point voltage balance system and method based on power-factor angle |
| CN106160541A (en) * | 2016-07-22 | 2016-11-23 | 南京理工大学 | The mid-point voltage Ripple Suppression system and method optimized based on off state |
-
2017
- 2017-10-27 CN CN201910921321.8A patent/CN110707958B/en active Active
- 2017-10-27 CN CN201711023190.9A patent/CN107834883B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5349522A (en) * | 1991-06-14 | 1994-09-20 | Hitachi, Ltd. | Method and apparatus for controlling the output voltage of an AC electrical system |
| CN101753044A (en) * | 2010-01-26 | 2010-06-23 | 北方工业大学 | Three-level midpoint potential balance control method based on zero-sequence voltage injection |
| CN104836464A (en) * | 2015-05-26 | 2015-08-12 | 东南大学 | Neutral-point-potential balance control device and method for direct current side of VIENNA rectifier |
| CN105305863A (en) * | 2015-10-10 | 2016-02-03 | 天津大学 | Point potential balance control method in three-level NPC inverter |
| CN106100402A (en) * | 2016-07-07 | 2016-11-09 | 西安理工大学 | A kind of T-shaped three-level inverter and neutral balance control method thereof |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108306536A (en) * | 2018-04-20 | 2018-07-20 | 西安科技大学 | A kind of NPC three-level inverters of SPWM modulation |
| CN108880297B (en) * | 2018-06-29 | 2020-12-04 | 南京理工大学 | Phase compensation device and method based on Vienna rectifier |
| CN108880297A (en) * | 2018-06-29 | 2018-11-23 | 南京理工大学 | A kind of phase compensation device and method based on Vienna rectifier |
| CN109347354A (en) * | 2018-11-26 | 2019-02-15 | 合肥科威尔电源系统有限公司 | Mid-point voltage Ripple Suppression device and method based on third-harmonic zero-sequence voltage |
| CN109951093A (en) * | 2019-03-13 | 2019-06-28 | 南京理工大学 | A kind of mid-point voltage control system and method based on hybrid parameter |
| CN110011322A (en) * | 2019-04-17 | 2019-07-12 | 山东大学 | Diode clamping tri-level inverter hybrid passive control system and method under the conditions of low voltage crossing |
| CN110581663B (en) * | 2019-10-16 | 2022-04-01 | 南京理工大学 | Phase compensation device and method of Vienna rectifier under low carrier ratio |
| CN110581663A (en) * | 2019-10-16 | 2019-12-17 | 南京理工大学 | Phase compensation device and method of Vienna rectifier under low carrier ratio |
| CN111342690A (en) * | 2020-03-13 | 2020-06-26 | 南京理工大学 | Split capacitor power unit multilevel converter and modulation strategy thereof |
| CN111342690B (en) * | 2020-03-13 | 2021-09-03 | 南京理工大学 | Modulation method of split capacitor power unit multilevel converter |
| CN114421837A (en) * | 2021-08-31 | 2022-04-29 | 宁波诺丁汉大学 | Discontinuous pulse width modulation algorithm with adaptive power factor |
| CN114421837B (en) * | 2021-08-31 | 2023-12-22 | 宁波诺丁汉大学 | Discontinuous pulse width modulation algorithm with self-adaptive power factor |
| CN115459553A (en) * | 2022-09-16 | 2022-12-09 | 山东艾诺仪器有限公司 | Method for controlling midpoint potential spwm of t-type three-level pwm rectifier |
| WO2024120381A1 (en) * | 2022-12-08 | 2024-06-13 | 青岛海信日立空调系统有限公司 | Power source apparatus and control method therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107834883B (en) | 2020-06-19 |
| CN110707958B (en) | 2021-09-21 |
| CN110707958A (en) | 2020-01-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110707958B (en) | Modulation wave interval division-based midpoint voltage control method | |
| CN106100402B (en) | A kind of T-type three-level inverter and its neutral balance control method | |
| CN104836464B (en) | Neutral-point-potential balance control device and method for direct current side of VIENNA rectifier | |
| CN109347354B (en) | Midpoint voltage ripple suppression device and method based on third harmonic injection | |
| CN103746584B (en) | Based on the multi-electrical level inverter neutral-point voltage balance method of carrier offset | |
| CN106532749B (en) | A kind of micro-capacitance sensor imbalance power and harmonic voltage compensation system and its application | |
| CN101951178A (en) | Method used for balancing three phases of direct current side voltages of chain power regulating device | |
| CN109494995B (en) | Neutral point potential balance control method suitable for VIENNA rectifier | |
| CN113839388B (en) | Current double-loop control method of active power filter based on hybrid load | |
| CN110429603B (en) | Six-switch seven-level active power filter and compensation method | |
| CN112290567B (en) | Three-phase power quality compensation device and method based on half-bridge converter | |
| CN105720587A (en) | Inter-phase voltage-sharing control method for DC bus of cascaded star-connected static synchronous compensator (STATCOM) | |
| CN104410083B (en) | Capacitance midpoint potential balancing device on SVG (Static VAR Generator) direct current side and control method of capacitance midpoint potential balancing device | |
| CN107196491A (en) | A kind of pair of buck combining inverter half periods current distortion suppression system and its method | |
| CN112186804A (en) | Method and system for bus voltage unbalance and harmonic compensation of island microgrid | |
| CN112532025A (en) | Method for optimizing Vienna rectifier input current when power grid is disturbed | |
| CN112104247A (en) | Neutral-point potential control method for medium-voltage three-level full-power converter of wind generating set | |
| CN113629763B (en) | Current control method and system for medium-voltage direct-hanging energy storage converter under non-ideal power grid | |
| CN109951093B (en) | Hybrid parameter-based midpoint voltage control system and method | |
| Antar et al. | Using seven-level cascade H-bridge inverter with HVDC system to improve power quality | |
| CN102780387A (en) | Control method of inverter | |
| CN204290329U (en) | A kind of SVG DC bus capacitor neutral-point potential balance device | |
| CN107612398B (en) | Passive control system and method for five-level NPC inverter | |
| CN113690888B (en) | Method for optimizing and processing APF control bandwidth and higher harmonic wave by FPGA | |
| CN114400719A (en) | New energy grid-connected control circuit and SST control method based on virtual synchronous machine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |