CN110677032A - Current sharing control method and device for staggered parallel PFC circuit and air conditioner - Google Patents

Current sharing control method and device for staggered parallel PFC circuit and air conditioner Download PDF

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Publication number
CN110677032A
CN110677032A CN201910999465.5A CN201910999465A CN110677032A CN 110677032 A CN110677032 A CN 110677032A CN 201910999465 A CN201910999465 A CN 201910999465A CN 110677032 A CN110677032 A CN 110677032A
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current
branch
pfc
sharing
duty ratio
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李超
游剑波
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Aux Air Conditioning Co Ltd
Ningbo Aux Electric Co Ltd
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Aux Air Conditioning Co Ltd
Ningbo Aux Electric Co Ltd
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Priority to CN201910999465.5A priority Critical patent/CN110677032A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/88—Electrical aspects, e.g. circuits
    • 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
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention provides a current sharing control method and device for a staggered parallel PFC circuit and an air conditioner, wherein the staggered parallel PFC circuit comprises two PFC branches which are symmetrically arranged, and the method comprises the following steps: acquiring actual bus voltage, target bus voltage and total current of the interleaved parallel PFC circuit and branch current of any PFC branch; obtaining an initial PWM signal with an initial duty cycle according to the actual bus voltage, the target bus voltage and the total current; and respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents. The technical scheme of the invention can simply and effectively solve the problem of uneven current of the branches of the staggered parallel PFC circuit and ensure that electric appliances such as an air conditioner and the like are in a reliable running state.

Description

Current sharing control method and device for staggered parallel PFC circuit and air conditioner
Technical Field
The invention relates to the technical field of air conditioners, in particular to a current sharing control method and device for staggered parallel PFC circuits and an air conditioner.
Background
The staggered parallel PFC circuit is widely applied to equipment such as a variable frequency air conditioner and the like, and has the characteristics of small input current and output current ripples, small branch power level and the like. The cross-connected PFC circuit needs to ensure that the total input current and the input voltage are in the same phase, and also needs to meet the requirement of the inductive current sharing of each branch circuit. However, in practical applications, parameters of components between two power branches have differences and discrepancies, which may cause uneven inductive current of each branch, which may cause uneven distribution of total power between the two branches, and even total energy of the PFC circuit is supplied by only a single branch. Therefore, the power allowance reserved by each branch is increased, and overcurrent faults or overtemperature faults can be generated, so that the reliability of the system is greatly reduced.
Disclosure of Invention
In order to solve the technical problem of branch non-current sharing of the staggered parallel PFC circuits, the invention provides a current sharing control method and device of the staggered parallel PFC circuits, an air conditioner and a storage medium.
In a first aspect, the present invention provides a current sharing control method for an interleaved parallel PFC circuit, where the interleaved parallel PFC circuit includes two PFC branches symmetrically arranged, and the method includes the following steps:
and acquiring the actual bus voltage, the target bus voltage and the total current of the staggered parallel PFC circuit and the branch current of any PFC branch.
Obtaining an initial PWM signal having an initial duty cycle based on the actual bus voltage, the target bus voltage, and the total current.
And respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
The current-sharing control method of the staggered parallel PFC circuits has the advantages that the initial PWM signals are obtained through the target bus voltage, the actual bus voltage and the circuit total current, and then current-sharing processing is carried out on the current of each PFC branch and the initial PWM signals respectively to obtain the current-sharing PWM signals for driving the switching tubes in each PFC branch. The problem of uneven flow of the branches of the staggered parallel PFC circuit is simply and effectively solved, so that the total power can be distributed between the two branches in a balanced manner, and the reliable operation state of electrical appliances such as an air conditioner with the PFC circuit is ensured.
Further, the process of obtaining the initial PWM signal specifically includes:
and comparing the actual bus voltage with the target bus voltage, and inputting a comparison result into a voltage loop regulator to obtain a target bus current.
And comparing the total current with the target bus current, and inputting a comparison result into a current loop regulator to obtain the initial PWM signal with the initial duty ratio.
The beneficial effect of adopting above-mentioned further scheme is that, through the voltage regulation to actual busbar voltage and target busbar voltage and the current regulation to target busbar current and total current, can obtain the initial PWM signal that has stable duty cycle, help carrying out the steady drive to the switch tube in the PFC circuit, guarantee the effect of flow equalizing.
Further, the process of obtaining the current-sharing PWM signal specifically includes:
and determining branch deviation current according to the total current and the branch current.
And respectively obtaining the current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the branch deviation current and the initial PWM signal.
The method has the advantages that the total current is the sum of the two branch currents, so that the other branch current can be determined after the total current and the one branch current are determined. By comparing the total current with the current of each branch, the deviation current of each branch can be obtained, and the current equalization processing is respectively carried out according to the deviation current of each branch, so that the current equalization of different PFC branches can be effectively ensured.
Further, the two PFC branches are a first PFC branch and a second PFC branch, respectively, and the branch offset current includes a first branch offset current of the first PFC branch and a second branch offset current of the second PFC branch.
The process of determining the first branch offset current comprises:
determining the first branch offset current according to a first formula, the first formula being:
Ierror1＝Is/2-I1。
wherein, Ierror1Representing said first branch offset current, IsRepresents the total current, I1Represents a branch current of the first PFC branch.
The process of determining the second branch offset current comprises:
determining the first branch offset current according to a second formula, wherein the second formula is as follows:
Ierror2＝Is/2-(Is-I1)。
wherein, Ierror2Representing the second branch offset current.
The further scheme has the advantages that only the total current of the AC parallel PFC circuit and the branch current of one PFC branch are required to be acquired, so that the realization cost is low, and the accuracy can be ensured.
Further, the current-sharing PWM signals for driving the switching tubes of the two PFC branches comprise a first current-sharing PWM signal with a first duty ratio and a second current-sharing PWM signal with a second duty ratio; the process of obtaining the current-sharing PWM signal specifically includes:
and when the first branch deviation current is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the upper limit value of a preset duty ratio adjustable range.
And when the first branch deviation current is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the lower limit value of the range of the preset duty ratio adjustable value.
And when the deviation current of the second branch circuit is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the upper limit value of a preset duty ratio adjustable range.
And when the deviation current of the second branch circuit is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the lower limit value of a preset duty ratio adjustable range.
Further, the process of obtaining the current-sharing PWM signal specifically further includes:
summing the first duty cycle and the adjusted value of the first duty cycle to obtain a first current-sharing PWM signal with the adjusted first duty cycle, wherein the first current-sharing PWM signal with the adjusted first duty cycle is used for driving a switching tube of the first PFC branch; and summing the second duty ratio and the adjustment value of the second duty ratio to obtain a second current-sharing PWM signal with the adjusted second duty ratio, wherein the second current-sharing PWM signal with the adjusted second duty ratio is used for driving a switching tube of the second PFC branch.
The beneficial effect of adopting the above further scheme is that the PWM signals for driving the switching tubes in the two PFC branches are respectively regulated in a current sharing manner, so that the balance of inductive currents in the two PFC branches can be effectively ensured, and the reliable operation state of equipment such as an air conditioner and the like can be ensured.
Further, the method comprises the following steps:
and acquiring the alternating current input voltage of the interleaved parallel PFC circuit.
And when the alternating current input voltage is greater than the preset current sharing bypass threshold voltage, the initial PWM signals are respectively output to the switching tubes of the two PFC branches.
The beneficial effect of adopting above-mentioned further scheme is that, through confirming the scope of PFC circuit alternating current input voltage, according to the influence of alternating current input voltage to the circuit, adopt the control strategy to the switch tube difference, can effectively prevent the wrong problem of flow equalizing that leads to of branch road current sampling inaccuracy.
In a second aspect, the present invention provides a current sharing control device for interleaved parallel PFC circuits, the device comprising:
and the acquisition module is used for acquiring the actual bus voltage, the target bus voltage and the total current of the interleaved parallel PFC circuit and the branch current of any PFC branch.
And the processing module is used for obtaining an initial PWM signal with an initial duty ratio according to the actual bus voltage, the target bus voltage and the total current.
And the driving module is used for respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
In a third aspect, the present invention provides an air conditioner, which includes a computer readable storage medium storing a computer program and a processor, and when the computer program is read and executed by the processor, the current sharing control method for interleaved parallel PFC circuits as described above is implemented.
Further, the air conditioner also comprises an interleaved parallel PFC circuit and a signal detection device, wherein the signal detection device is used for detecting at least one of alternating current input voltage, actual bus voltage, total current and branch current of the interleaved parallel PFC circuit.
In a fourth aspect, the present invention provides a computer-readable storage medium, where a computer program is stored, and when the computer program is read and executed by a processor, the method for current sharing control of interleaved parallel PFC circuits as described above is implemented.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an interleaved parallel PFC circuit;
fig. 2 is a schematic flow chart illustrating a current sharing control method for interleaved PFC circuits according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of obtaining an initial PWM signal according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a schematic diagram of obtaining a current-sharing PWM signal according to an embodiment of the present invention;
fig. 5 is a block diagram of a current sharing control device of an interleaved PFC circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an interleaved PFC circuit and a signal detection device according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
As shown in fig. 1, the interleaved PFC circuit may include two Boost PFC branches symmetrically disposed, each PFC branch includes an inductor, a diode, and a switching tube, and the switching tubes in the two branches are respectively T1 and T2. Each PFC branch switch operates in a 180-degree staggered state and bears half of the total output power of the staggered parallel PFC circuits. Because parameters of corresponding components in the two PFC branches may have difference and discreteness, inductive current in each PFC branch is not uniform, power distribution is not balanced, and stable operation of equipment such as an air conditioner is influenced.
As shown in fig. 2, a current sharing control method for interleaved parallel PFC circuits according to an embodiment of the present invention includes the following steps:
and S1, acquiring the actual bus voltage, the target bus voltage and the total current of the interleaved parallel PFC circuit and the branch current of any PFC branch.
The actual bus voltage can be recorded as VdcTarget bus voltage VrefTotal current IsAnd the actual bus voltage, the total current and the branch current can be acquired from the interleaved parallel PFC circuit.
And S2, obtaining an initial PWM signal with an initial duty ratio according to the actual bus voltage, the target bus voltage and the total current.
The initial duty cycle may be noted as D.
And S3, respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
In this embodiment, an initial PWM signal is obtained through a target bus voltage, an actual bus voltage, and a circuit total current, and then a current-sharing process is performed with the initial PWM signal based on a current of each PFC branch, so as to obtain a current-sharing PWM signal for driving a switching tube in each PFC branch. The problem of uneven flow of the branches of the staggered parallel PFC circuit is simply and effectively solved, so that the total power can be distributed between the two branches in a balanced manner, and the reliable operation state of electrical appliances such as an air conditioner with the PFC circuit is ensured.
Preferably, the process of obtaining the initial PWM signal specifically includes:
and comparing the actual bus voltage with the target bus voltage, and inputting a comparison result into a voltage loop regulator to obtain a target bus current.
The target bus current is recorded as Iref。
And comparing the total current with the target bus current, and inputting a comparison result into a current loop regulator to obtain the initial PWM signal with the initial duty ratio.
In particular, as shown in fig. 3, the above method may be implemented by a loop control unit. Firstly, V is firstlydcAnd VrefInputting the comparison result into the voltage loop regulator to obtain IrefThe voltage loop regulator may regulate the average amplitude of the current reference signal, regulate VdcInfinitely close to VrefThe output voltage is kept constant. Then I isrefAnd IsThe input current regulator outputs an initial PWM signal with an initial duty ratio D, namely PWM in the figure indicates, and the current regulator can regulate the inductive current so that the input current waveform follows the input voltage waveform. It should be noted that the comparator, the voltage regulator and the current regulator can be implemented by software functions of the control device, or by building corresponding hardware circuits.
In the preferred embodiment, the initial PWM signal with a stable duty ratio can be obtained by voltage regulation of the actual bus voltage and the target bus voltage and current regulation of the target bus current and the total current, which is helpful for stably driving the switching tube in the PFC circuit and ensures the current equalizing effect.
Preferably, the process of obtaining the current-sharing PWM signal specifically includes:
and determining branch deviation current according to the total current and the branch current.
And respectively obtaining the current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the branch deviation current and the initial PWM signal.
In the preferred embodiment, since the total current is the sum of the two branch currents, after the total current and one branch current are determined, the other branch current can be determined. By comparing the total current with the current of each branch, the deviation current of each branch can be obtained, and the current equalization processing is respectively carried out according to the deviation current of each branch, so that the current equalization of different PFC branches can be effectively ensured.
Preferably, the two PFC branches are a first PFC branch and a second PFC branch, respectively, and the branch offset current includes a first branch offset current of the first PFC branch and a second branch offset current of the second PFC branch. The switch transistor T1 is located in the first PFC branch, and the switch transistor T2 is located in the second PFC branch.
The branch current of the first PFC branch can be recorded as I1The branch current of the second PFC branch is I2Wherein, I1+I2＝Is. The first branch offset current can be recorded as Ierror1The second branch has a bias current of Ierror2。
The process of determining the first branch offset current comprises:
determining the first branch offset current according to a first formula, the first formula being:
Ierror1＝Is/2-I1。
the process of determining the second branch offset current comprises:
determining the first branch offset current according to a second formula, wherein the second formula is as follows:
Ierror2＝Is/2-(Is-I1)。
specifically, as shown in fig. 4, the method may be implemented by a current sharing control unit. Firstly, I issAnd I1Input comparator, and subtracting to obtain I2While simultaneously mixing IsInput differentiator, obtained IsMedian value of (I)s/2, followed by reaction of Is[ 2 ] and I1Input comparator, and subtracting to obtain Ierror1While simultaneously mixing Is[ 2 ] and I2Input comparator, and subtracting to obtain Ierror2. It should be noted that the comparator and the differentiator can be implemented by software functions of the control device, and can also be implemented by building corresponding hardware circuits.
In the preferred embodiment, only the total current of the alternating-current parallel PFC circuit and the branch current of one PFC branch circuit need to be acquired, so that the cost is low, and the accuracy can be ensured.
Preferably, the current-sharing PWM signals for driving the switching tubes of the two PFC branches include a first current-sharing PWM signal having a first duty ratio and a second current-sharing PWM signal having a second duty ratio.
The first current-sharing PWM signal can be written as PWM1 with a duty cycle of D1, and the second current-sharing PWM signal can be written as PWM2 with a duty cycle of D2.
The process of obtaining the current-sharing PWM signal specifically includes:
and when the first branch deviation current is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the upper limit value of a preset duty ratio adjustable range.
And when the first branch deviation current is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the lower limit value of the range of the preset duty ratio adjustable value.
And when the deviation current of the second branch circuit is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the upper limit value of a preset duty ratio adjustable range.
And when the deviation current of the second branch circuit is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the lower limit value of a preset duty ratio adjustable range.
Specifically, the adjustment value of the first duty ratio may be recorded as Derror1The adjustment value of the second duty ratio is Derror2The maximum value of the preset deviation stable interval is Ierror0Minimum value of-Ierror0The upper limit value of the preset duty ratio adjustable value range is Derror0The lower limit value is-Derror0。
It should be noted that the above maximum value Ierror0And a minimum value-Ierror0The absolute values of the two are not necessarily the same, which is only illustrated schematically, and can be adjusted according to actual conditions. The above upper limit value Derror0And a lower limit value of-Derror0The absolute values of the two are not necessarily the same, and can be adjusted according to actual conditions.
As shown in fig. 4, the above method can be implemented by the current sharing control unit. Obtaining Ierror1And Ierror2Then, the initial PWM signal is added to Ierror1Inputting the current-sharing regulator 1, obtaining a first current-sharing PWM signal with a first duty ratio D, namely PWM1 in the figure, and simultaneously adding the initial PWM signal and Ierror2The input to the current share regulator 2 obtains a second current share PWM signal with a second duty cycle D, referred to as PWM2 in the figure. It should be noted that the above-mentioned current equalizing regulator can be implemented by software function of the control device, and can also be implemented by building a corresponding hardware circuit.
More specifically, as an example, the maximum value of the preset deviation stabilization interval is 0.5A, the minimum value is-0.5A, the upper limit value of the preset duty ratio adjustable range is 20%, the lower limit value of the preset duty ratio adjustable range is-20%, and the preset value of the duty ratio adjustment value is 1%.
If Ierror1If > 0.5A, then Derror1Increasing by 1% according to each regulation period until the change is 20%;
if Ierror1< -0.5A, then Derror1According to each regulation cycle, the reduction was 1% until the change was-20%. 20% here denotes Derror1Increment of (2), -20% for Derror1The decrement of (c).
If Ierror2If > 0.5A, then Derror2Increasing by 1% according to each regulation period until the change is 20%;
if Ierror2< -0.5A, then Derror2According to each regulation cycle, the reduction was 1% until the change was-20%. 20% here denotes Derror2Increment of (2), -20% for Derror2The decrement of (c).
It should be noted that the specific values in the above examples are only illustrative, and all of them can be adjusted according to actual situations. In addition, the preset value of 1% can ensure the efficiency and the smoothness of the adjustment, and the over-high value can cause over-adjustment, and the over-low value can cause over-slow adjustment speed.
Preferably, the process of obtaining the current-sharing PWM signal further includes:
summing the first duty cycle and the adjusted value of the first duty cycle to obtain a first current-sharing PWM signal with the adjusted first duty cycle, wherein the first current-sharing PWM signal with the adjusted first duty cycle is used for driving a switching tube of the first PFC branch; and summing the second duty ratio and the adjustment value of the second duty ratio to obtain a second current-sharing PWM signal with the adjusted second duty ratio, wherein the second current-sharing PWM signal with the adjusted second duty ratio is used for driving a switching tube of the second PFC branch.
Specifically, since the first current-sharing PWM signal and the second current-sharing PWM signal are both in the dynamic adjustment process, that is, the duty ratios thereof are subjected to fine adjustment, the adjusted first duty ratio D1 and second duty ratio D2 are respectively used as the occupation of the first current-sharing PWM signal and the second current-sharing PWM signalSpace ratio. At the obtaining of Derror1And Derror2Then, it can be added to the initial duty cycle D, respectively, i.e.:
D1＝D+Derror1。
D2＝D+Derror2。
a first current-sharing PWM signal with a duty cycle D1 is obtained for driving the switching transistor T1 of the first PFC branch, and a second current-sharing PWM signal with a duty cycle D2 is obtained for driving the switching transistor T2 of the second PFC branch.
In the preferred embodiment, the PWM signals for driving the switching tubes in the two PFC branches are respectively regulated in a current-sharing manner, so that the balance of inductive currents in the two PFC branches can be effectively ensured, and the reliable operation of the air conditioner and other equipment can be ensured.
Preferably, the method further comprises the steps of:
and acquiring the alternating current input voltage of the interleaved parallel PFC circuit.
And when the alternating current input voltage is greater than the preset current sharing bypass threshold voltage, the initial PWM signals are respectively output to the switching tubes of the two PFC branches.
Specifically, the AC input voltage can be recorded as VacThe preset current-sharing bypass threshold voltage is Vac_maxThe alternating current input voltage can be acquired from the interleaved parallel PFC circuit. When V isac＞Vac_maxWhen the voltage is zero, the conduction time of the switch tubes T1 and T2 is very short, and is VacAt a relatively high level, V is obtained by rectification of the circuit itselfdcIs also relatively high, i.e. VdcAnd VrefThe difference of (2) is small, the PFC boosting requirement is small, and the branch current can be obtained by sampling through the resistor, so that the time of the current flowing through the sampling resistor is short, and the accurate sampling of the branch current cannot be met. In order to prevent the occurrence of the false current sharing condition, the current sharing control unit is bypassed, and two paths of current sharing PWM signals are directly obtained from the initial PWM signal and respectively drive the switch tubes T1 and T2. Because the current-sharing control unit can be realized by a software control function, when the bypass condition is met, the control function is not called.
Accordingly, when Vac＜Vac_maxThen, the above steps S1 to S3 are performed. Vac_maxCan be set according to actual test or use conditions.
In the preferred embodiment, by determining the range of the alternating-current input voltage of the PFC circuit and adopting different control strategies for the switching tube according to the influence of the alternating-current input voltage on the circuit, the problem of error current sharing caused by inaccurate sampling of branch current can be effectively prevented.
As shown in fig. 5, a current sharing control device of an interleaved PFC circuit according to an embodiment of the present invention includes:
and the acquisition module is used for acquiring the actual bus voltage, the target bus voltage and the total current of the interleaved parallel PFC circuit and the branch current of any PFC branch.
And the processing module is used for obtaining an initial PWM signal with an initial duty ratio according to the actual bus voltage, the target bus voltage and the total current.
And the driving module is used for respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
In another embodiment of the present invention, a current sharing control apparatus for interleaved PFC circuits includes a memory and a processor. The memory is used for storing the computer program. The processor is configured to implement the current sharing control method for the interleaved parallel PFC circuit as described above when executing the computer program.
It should be noted that the apparatus may be a computer apparatus such as a micro-processing system.
In another embodiment of the present invention, an air conditioner includes the current sharing control device with the interleaved PFC circuits as described above. In other words, the air conditioner comprises a computer readable storage medium storing a computer program and a processor, and when the computer program is read and executed by the processor, the current sharing control method of the interleaved parallel PFC circuit is realized.
Preferably, as shown in fig. 6, the air conditioner further comprises an interleaving parallel PFC circuit and a signal detection device, wherein the signal detection device is used for detecting the interleavingAC input voltage V of cross-parallel PFC circuitacActual bus voltage VdcTotal current IsAnd a branch current, e.g. the current I of the first PFC branch1. The switching tubes T1 and T2 in the two branches of the interleaved parallel PFC circuit are driven by a first current-sharing PWM signal PWM1 and a second current-sharing PWM signal PMW2, respectively.
The sampling resistors with small resistance values, such as RS and RS1 in the figure, can be connected in series in the PFC circuit, so that a voltage difference can be generated between two ends of the sampling resistor when a current flows through the sampling resistor, and a corresponding signal can be obtained through AD sampling processing. A current transformer can be connected in series in the circuit, and the induction current value of the current transformer can be subjected to AD sampling processing to obtain a corresponding signal.
In another embodiment of the present invention, a computer-readable storage medium has stored thereon a computer program, which when executed by a processor, implements the current sharing control method for interleaved PFC circuits as described above.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (11)

1. A current sharing control method of an interleaved parallel PFC circuit is disclosed, the interleaved parallel PFC circuit comprises two PFC branches which are symmetrically arranged, and the method is characterized by comprising the following steps:
acquiring actual bus voltage, target bus voltage and total current of the interleaved parallel PFC circuit and branch current of any PFC branch;
obtaining an initial PWM signal with an initial duty cycle according to the actual bus voltage, the target bus voltage and the total current;
and respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
2. The method according to claim 1, wherein the obtaining the initial PWM signal comprises:
comparing the actual bus voltage with the target bus voltage, and inputting a comparison result into a voltage loop regulator to obtain a target bus current;
and comparing the total current with the target bus current, and inputting a comparison result into a current loop regulator to obtain the initial PWM signal with the initial duty ratio.
3. The method according to claim 1, wherein the obtaining the current-sharing PWM signal comprises:
determining branch deviation current according to the total current and the branch current;
and respectively obtaining the current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the branch deviation current and the initial PWM signal.
4. The method according to claim 3, wherein the two PFC branches are a first PFC branch and a second PFC branch, and the branch offset current includes a first branch offset current of the first PFC branch and a second branch offset current of the second PFC branch;
the process of determining the first branch offset current comprises:
determining the first branch offset current according to a first formula, the first formula being:
Ierror1＝Is/2-I1；
wherein, Ierror1Representing said first branch offset current, IsRepresents the total current, I1Represents a branch current of the first PFC branch;
the process of determining the second branch offset current comprises:
determining the first branch offset current according to a second formula, wherein the second formula is as follows:
Ierror2＝Is/2-(Is-I1)；
wherein, Ierror2Representing the second branch offset current.
5. The method for current sharing control of interleaved PFC circuits according to claim 4, wherein the current sharing PWM signals for driving the switching transistors of the two PFC branches comprise a first current sharing PWM signal having a first duty cycle and a second current sharing PWM signal having a second duty cycle; the process of obtaining the current-sharing PWM signal specifically includes:
when the first branch deviation current is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the upper limit value of a preset duty ratio adjustable range;
when the first branch deviation current is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the first duty ratio by a preset value in each regulating period until the regulating value of the first duty ratio reaches the lower limit value of a preset duty ratio regulating value range;
when the second branch deviation current is larger than the maximum value of a preset deviation stable interval, increasing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the upper limit value of a preset duty ratio adjustable range;
and when the deviation current of the second branch circuit is smaller than the minimum value of a preset deviation stable interval, reducing the regulating value of the second duty ratio by a preset value in each regulating period until the regulating value of the second duty ratio reaches the lower limit value of a preset duty ratio adjustable range.
6. The method according to claim 5, wherein the obtaining the current-sharing PWM signal further comprises:
summing the first duty cycle and the adjusted value of the first duty cycle to obtain a first current-sharing PWM signal with the adjusted first duty cycle, wherein the first current-sharing PWM signal with the adjusted first duty cycle is used for driving a switching tube of the first PFC branch; and summing the second duty ratio and the adjustment value of the second duty ratio to obtain a second current-sharing PWM signal with the adjusted second duty ratio, wherein the second current-sharing PWM signal with the adjusted second duty ratio is used for driving a switching tube of the second PFC branch.
7. The method for current sharing control of interleaved PFC circuits according to any of claims 1-6, further comprising the steps of:
acquiring alternating current input voltage of the interleaved parallel PFC circuit;
and when the alternating current input voltage is greater than the preset current sharing bypass threshold voltage, the initial PWM signals are respectively output to the switching tubes of the two PFC branches.
8. A current sharing control device for interleaving PFC circuits is characterized by comprising:
the acquisition module is used for acquiring the actual bus voltage, the target bus voltage and the total current of the interleaved parallel PFC circuit and the branch current of any PFC branch;
the processing module is used for obtaining an initial PWM signal with an initial duty ratio according to the actual bus voltage, the target bus voltage and the total current;
and the driving module is used for respectively obtaining current-sharing PWM signals for driving the switching tubes of the two PFC branches according to the initial PWM signals and the branch currents.
9. An air conditioner comprising a computer readable storage medium storing a computer program and a processor, wherein the computer program is read by the processor and executed to implement the current sharing control method of the interleaved PFC circuit according to any one of claims 1 to 7.
10. The air conditioner of claim 9, further comprising an interleaved PFC circuit and signal detection means for detecting at least one of an ac input voltage, an actual bus voltage, a total current, and a branch current of the interleaved PFC circuit.
11. A computer-readable storage medium, wherein the storage medium stores thereon a computer program, and when the computer program is read and executed by a processor, the method for current sharing control of interleaved PFC circuits according to any one of claims 1 to 7 is implemented.
CN201910999465.5A 2019-10-21 2019-10-21 Current sharing control method and device for staggered parallel PFC circuit and air conditioner Pending CN110677032A (en)

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