CN112713796B - DC/AC control method and device of bidirectional direct current charger in off-grid mode - Google Patents
DC/AC control method and device of bidirectional direct current charger in off-grid mode Download PDFInfo
- Publication number
- CN112713796B CN112713796B CN202011507024.8A CN202011507024A CN112713796B CN 112713796 B CN112713796 B CN 112713796B CN 202011507024 A CN202011507024 A CN 202011507024A CN 112713796 B CN112713796 B CN 112713796B
- Authority
- CN
- China
- Prior art keywords
- regulator
- wave
- output result
- conversion
- control
- 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.)
- Active
Links
Images
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
- H02M7/539—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 with automatic control of output wave form or frequency
- H02M7/5395—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 with automatic control of output wave form or frequency by pulse-width modulation
-
- 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
- H02J3/01—Arrangements for reducing harmonics or ripples
-
- 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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
-
- 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
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33584—Bidirectional 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
- 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
- Y02E40/40—Arrangements for reducing harmonics
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention provides a DC/AC control method and a device of a bidirectional direct current charger in an off-grid mode, wherein the DC/AC control method comprises the following steps: collecting the voltage of the alternating current output by the DC/AC conversion; obtaining a voltage difference value by subtracting the given voltage from the voltage of the alternating current; judging whether a condition of triggering wave-by-wave current limiting is met; if the condition of triggering wave-by-wave current limiting is not met, the voltage difference value is regulated by a PI regulator and a PR regulator, and DC/AC conversion control is performed according to the output result of the PI regulator and the output result of the PR regulator; if the condition of triggering wave-by-wave current limiting is achieved, the voltage difference value is regulated by a PI regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator. The invention not only can reduce the harmonic content of the alternating current output voltage, but also can avoid current oscillation caused by alternating current output voltage jitter when wave-by-wave current limiting is performed, and reduce the probability of triggering hardware overcurrent protection, thereby improving the load carrying capacity of the bidirectional direct current charger in an off-grid mode.
Description
Technical Field
The invention relates to the technical field of power supply control, in particular to a DC/AC control method and a DC/AC control device for a bidirectional direct current charger in an off-grid mode.
Background
A topology structure of a 6.6kw bidirectional dc charger in the related art is shown in fig. 1, and includes a first conversion module composed of switching tubes S1 to S4 and a second conversion module composed of S5 to S12 and a resonant transformer T1, one side of the first conversion module is connected with filter inductors L1 and L2, the second conversion module further includes resonant capacitors C2 and C3 and a resonant inductor L3, and a bus capacitor C1 is further connected between the first conversion module and the second conversion module. One side of the first conversion module is connected with the nonlinear off-grid load through switches K2 and K3, and is connected with the grid through switches K3 and K4, and one side of the second conversion module is connected with a vehicle-end battery.
As shown in fig. 1, the bidirectional dc charger supports bidirectional energy flow, that is, the bidirectional dc charger can work in a forward charging mode and a reverse discharging mode. In the forward charging mode, the charger takes power from a power grid, performs AC/DC conversion into direct current through the first conversion module, and performs DC/DC conversion through the second conversion module to directly charge the battery. In a reverse discharge mode, direct current output by a vehicle-end battery is subjected to DC/DC conversion into proper direct current voltage through the second conversion module, and is subjected to DC/AC conversion through the first conversion module to obtain alternating current, when the switches K4 and K5 are closed and K2 and K3 are disconnected, the generated alternating current is sent to a power grid, and at the moment, the inverter is equivalent to a current source; when the switches K4, K5 are open and K2, K3 are closed, the generated ac power is supplied to the off-grid load, the inverter acts as a voltage source, and the operating mode at this time can also be referred to as an off-grid mode.
In order to bring motor impact load and rectification load in an off-grid mode, a first converter is required to have a current peak value which is 3 times of a rated current effective value under the condition of load (namely, the requirement of a minimum load peak current ratio of 3: 1 is met), and when the load current exceeds 3 times of a rated current value, current is required to be chopped, so that the current is ensured not to exceed a hardware protection threshold value. However, under the existing control strategy, when the load current is triggered to the wave-by-wave current limiting threshold, in order to ensure that the current is stabilized at the threshold, the ac output voltage may distort and sink at the chopping current, the ac output voltage at this moment may contain high order harmonics such as 3, 5, and 7, and the existing control strategy may control the high order harmonics such as 3, 5, and 7 to zero, which may cause distortion and jitter of the output ac voltage to be more severe, and further may cause the current oscillation to reach the first conversion module ac hardware overcurrent protection, and reduce its load carrying capacity.
Disclosure of Invention
The invention aims to solve the technical problems and provides a DC/AC control method and a device of a bidirectional direct current charger in an off-grid mode, which not only can reduce the harmonic content of alternating current output voltage when the bidirectional direct current charger is under the off-grid mode and is provided with a non-linear load, but also can avoid current oscillation caused by the vibration of the alternating current output voltage when wave-by-wave current limiting is performed, and reduce the probability of triggering hardware overcurrent protection, thereby improving the carrying capacity of the bidirectional direct current charger in the off-grid mode.
The technical scheme adopted by the invention is as follows:
a DC/AC control method under an off-grid mode of a bidirectional direct current charger is disclosed, the bidirectional direct current charger comprises a first conversion module and a second conversion module, when the bidirectional direct current charger works in the off-grid mode, direct current of a vehicle-end battery is subjected to DCDC conversion through the second conversion module and is subjected to DC/AC conversion through the first conversion module to obtain alternating current to be supplied to an off-grid load, and the DC/AC control method comprises the following steps: collecting the voltage of the alternating current output by DC/AC conversion; obtaining a voltage difference value by subtracting the given voltage from the voltage of the alternating current; judging whether the condition of triggering wave-by-wave current limiting is achieved; if the condition of triggering wave-by-wave current limiting is not met, the voltage difference value is regulated by a PI (proportional Integral) regulator and a PR (proportional Integral) regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator and the output result of the PR regulator; and if the condition of triggering wave-by-wave current limiting is met, regulating the voltage difference value by a PI regulator, and carrying out DC/AC conversion control according to the output result of the PI regulator.
Performing DC/AC conversion control according to the output result of the PI regulator and the output result of the PR regulator, specifically comprising: and adding the output result of the PI regulator and the output result of the PR regulator, inputting the added sum value into an SPWM (Sinusoidal Pulse Width Modulation) module, and generating and outputting a corresponding SPWM signal by the SPWM module so as to control the first conversion module.
Performing DC/AC conversion control according to the output result of the PI regulator and the output result of the PR regulator, further comprising: and carrying out amplitude limiting on the output result of the PR regulator, adding the output result of the PI regulator and the output result of the PR regulator after amplitude limiting, inputting the sum obtained by adding into an SPWM module, and generating and outputting a corresponding SPWM signal by the SPWM module so as to control the first conversion module.
And the opening and closing of a switch of the branch where the PR regulator is positioned are controlled to control the cutting-off and the connection of the PR regulator.
The PR regulator is a 1, 3, 5 and 7 th harmonic PR regulator, and the transfer function of the PR regulator is as follows:
wherein, KprIs a proportionality coefficient, KrIs the resonance coefficient, wckTo cut-off frequency, wkK is the harmonic order for the resonant frequency.
And judging whether the current of the off-grid load reaches a wave-by-wave current limiting threshold value or not to trigger the wave-by-wave current limiting condition.
When the bidirectional direct current charger works in the off-grid mode, direct current of a vehicle-end battery is subjected to DCDC conversion through the second conversion module and is subjected to DC/AC conversion through the first conversion module to obtain alternating current to be supplied to an off-grid load, and the DC/AC control device comprises: the voltage acquisition unit is used for acquiring the voltage of the alternating current output by DC/AC conversion; the difference value calculating unit is used for calculating the difference between the given voltage and the voltage of the alternating current to obtain a voltage difference value; the judging unit is used for judging whether the condition of triggering wave-by-wave current limiting is achieved or not; and the control unit is used for regulating the voltage difference value through a PI regulator and a PR regulator when the condition of triggering wave-by-wave current limiting is not met, carrying out DC/AC conversion control according to the output result of the PI regulator and the output result of the PR regulator, regulating the voltage difference value through the PI regulator when the condition of triggering wave-by-wave current limiting is met, and carrying out DC/AC conversion control according to the output result of the PI regulator.
The control unit is specifically used for adding the output result of the PI regulator and the output result of the PR regulator when the condition of triggering wave-by-wave current limiting is not reached, inputting the added sum value into the SPWM module, the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module, and when the condition of triggering wave-by-wave current limiting is reached, the output result of the PI regulator is input into the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
The control unit is further used for carrying out amplitude limiting on the output result of the PR regulator when the condition of triggering wave-by-wave current limiting is not reached, adding the output result of the PI regulator and the output result of the PR regulator after amplitude limiting, inputting the sum obtained by adding into the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal so as to control the first conversion module.
The control unit controls the cutting-off and the connection of the PR regulator by controlling the opening and the closing of a switch of a branch where the PR regulator is located.
The invention has the beneficial effects that:
according to the invention, whether the condition of triggering wave-by-wave current limiting is reached is judged, when the condition of triggering wave-by-wave current limiting is not reached, the voltage difference value is regulated by the PI regulator and regulated by the PR regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator and the output result of the PR regulator, when the condition of triggering wave-by-wave current limiting is reached, the voltage difference value is regulated by the PI regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator, so that the harmonic content of alternating current output voltage can be reduced when the bidirectional direct current charger is in an off-grid mode with non-linear load, current oscillation caused by the jitter of the alternating current output voltage when the wave-by-wave current limiting is acted can be avoided, the probability of triggering hardware overcurrent protection is reduced, and the carrying capacity of the bidirectional direct current charger in the off-grid mode is improved.
Drawings
Fig. 1 is a topology diagram of a bidirectional dc charger in the related art;
fig. 2 is a schematic diagram of a control structure of the bidirectional dc charger according to an embodiment of the present invention;
fig. 3 is a flowchart of a DC/AC control method of the bidirectional DC charger in the off-grid mode according to the embodiment of the present invention;
fig. 4 is a schematic control structure diagram of a bidirectional dc charger according to another embodiment of the present invention;
fig. 5 is a block diagram illustrating a DC/AC control device of the bidirectional DC charger in an off-grid mode according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1 and fig. 2, and referring to the background art, the bidirectional dc charger according to the embodiment of the present invention includes a first conversion module and a second conversion module. When the bidirectional direct-current charger works in the off-grid mode, the energy flow direction of the bidirectional direct-current charger is as shown in fig. 2, direct current of the vehicle-end battery is subjected to DCDC conversion through the second conversion module, and is subjected to DC/AC conversion through the first conversion module. In an embodiment of the present invention, the switching tubes in the first and second conversion modules may be Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs).
As shown in fig. 3, the DC/AC control method in the off-grid mode of the bidirectional DC charger according to the embodiment of the present invention includes the following steps:
and S1, collecting the voltage of the alternating current output by the DC/AC conversion.
And S2, obtaining a voltage difference value by subtracting the given voltage from the voltage of the alternating current.
Referring to fig. 2, in one embodiment of the present invention, given voltage uref ═ U × sin (wt), where U is a given target DC/AC output voltage value, 311V may be taken, and wt is the corresponding grid angular frequency. Given voltage urefWith the voltage u of the alternating current collectedoObtaining a voltage difference value u by differenceerr。
And S3, judging whether the condition of triggering wave-by-wave current limiting is reached.
In one embodiment of the invention, the off-grid load current can be determined by determining whether the off-grid load current isAnd the wave-by-wave current limiting threshold value is reached to judge whether the condition of triggering the wave-by-wave current limiting is reached. Specifically, when the current of the off-grid load is lower than the wave-by-wave current limiting threshold IlimWhen the current of the off-grid load is larger than or equal to the wave-by-wave current limiting threshold value I, the wave-by-wave current limiting does not worklimAnd in the time, the wave-by-wave current limiting function is realized, namely, the wave-by-wave current limiting working mode is entered.
In one embodiment of the invention, the wave-by-wave current limiting threshold value IlimCan be set by: generating a reference level by configuring a comparator inside a DSP (Digital Signal Processing) implementing the method of the invention, or generating a reference level by an external reference power supply and an external operational amplifier, and limiting a threshold I wave by wavelimCorresponding to the reference level. Wave-by-wave current limiting threshold IlimThe specific correspondence with the reference level depends on hardware parameters and requirements for overcurrent protection, etc. In one embodiment of the present invention, the reference levels are 1.5V and 2.5V, respectively corresponding wave-by-wave current limiting threshold IlimNegative peak-50A and positive peak 50A.
And S4, if the condition of triggering wave-by-wave current limiting is not reached, adjusting the voltage difference value through a PI adjuster and a PR adjuster, and controlling DC/AC conversion according to the output result of the PI adjuster and the output result of the PR adjuster.
And S5, if the condition of triggering wave-by-wave current limiting is achieved, the voltage difference value is regulated by a PI regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator.
In one embodiment of the invention, the transfer function of the PI regulator is:
wherein, KpIs a proportionality coefficient, KIIs an integral coefficient.
The PR regulator is a 1, 3, 5 and 7 th harmonic PR regulator, and plays a main role in carrying out PR control on high-order harmonics such as 3, 5 and 7, and the transfer function of the PR regulator is as follows:
wherein, KprIs a proportionality coefficient, KrIs the resonance coefficient, wckTo cut-off frequency, wkK is the harmonic order for the resonant frequency.
As shown in fig. 2, in the embodiment of the present invention, the PI regulator branch is connected in parallel with the PR regulator branch, and the PR regulator branch is provided with a switch K1, where K1 is a controllable switch and is controlled by software.
If the condition of triggering wave-by-wave current limiting is not met, the switch K1 can be controlled to be closed so as to control the PR regulator to be switched in, and the PI regulator and the PR regulator work together to control the DC/AC conversion. Specifically, the output result of the PI regulator and the output result of the PR regulator may be added, the added sum is input to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
If the condition triggering the ripple-through current limiting is reached, i.e. the ripple-through current limiting mode of operation is entered, the switch K1 can be controlled to open to control the PR regulator to switch off, and only the PI regulator acts to control the DC/AC conversion. Specifically, the output result of the PI regulator may be input to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
According to the DC/AC control method under the off-grid mode of the bidirectional direct current charger, whether the condition of triggering wave-by-wave current limiting is achieved or not is judged, when the condition of triggering wave-by-wave current limiting is not achieved, the voltage difference value is adjusted through the PI adjuster and the PR adjuster, DC/AC conversion control is conducted according to the output result of the PI adjuster and the output result of the PR adjuster, when the condition of triggering wave-by-wave current limiting is achieved, the voltage difference value is adjusted through the PI adjuster, DC/AC conversion control is conducted according to the output result of the PI adjuster, therefore, the harmonic content of alternating current output voltage can be reduced when the bidirectional direct current charger is in an off-grid mode with non-linear load, current oscillation caused by shaking of the alternating current output voltage when wave-by-wave current limiting is achieved can be avoided, and the probability of triggering hardware overcurrent protection is reduced, therefore, the load carrying capacity of the bidirectional direct current charger in an off-grid mode is improved.
Further, as shown in fig. 4, a clipping module may be connected to a branch of the PR adjuster, and when the condition of triggering the wave-by-wave current limiting is not met, the output result of the PR adjuster is clipped, the output result of the PI adjuster is added to the clipped output result of the PR adjuster, the added sum is input to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module. The limiting value can be set through a limited number of experiments according to actual control requirements, and is not limited to a specific value here. By limiting the output of the PR regulator, jitter of the output ac voltage can be further effectively suppressed.
The invention further provides a DC/AC control device of the bidirectional direct current charger in the off-grid mode, which corresponds to the DC/AC control method of the bidirectional direct current charger in the off-grid mode.
As shown in fig. 5, the DC/AC control device in the off-grid mode of the bidirectional DC charger according to the embodiment of the present invention includes a voltage acquisition unit 10, a difference calculation unit 20, a determination unit 30, and a control unit 40. The voltage acquisition unit 10 is used for acquiring the voltage of the alternating current output by the DC/AC conversion; the difference value calculating unit 20 is configured to obtain a voltage difference value by subtracting the given voltage from the voltage of the alternating current; the judging unit 30 is used for judging whether the condition of triggering wave-by-wave current limiting is reached; the control unit 40 is used for adjusting the voltage difference value through the PI regulator and the PR regulator when the condition of triggering wave-by-wave current limiting is not met, performing DC/AC conversion control according to the output result of the PI regulator and the output result of the PR regulator, adjusting the voltage difference value through the PI regulator when the condition of triggering wave-by-wave current limiting is met, and performing DC/AC conversion control according to the output result of the PI regulator.
Referring to FIG. 2, in one embodiment of the present invention, a given voltage urefU sin (wt), where U is a given target DC/AC output voltage value, 311V may be taken, and wt is the corresponding grid angular frequency. Given voltage urefWith the voltage u of the alternating current collectedoMake a differenceObtain the voltage difference uerr。
In an embodiment of the present invention, the determining unit 30 may determine whether a condition for triggering the wave-by-wave current limiting is met by determining whether the current of the off-grid load reaches a wave-by-wave current limiting threshold. Specifically, when the current of the off-grid load is lower than the wave-by-wave current limiting threshold IlimWhen the current of the off-grid load is larger than or equal to the wave-by-wave current limiting threshold value I, the wave-by-wave current limiting does not worklimAnd in the time, the wave-by-wave current limiting function is realized, namely, the wave-by-wave current limiting working mode is entered.
In one embodiment of the invention, the wave-by-wave current limiting threshold value IlimCan be set by: generating a reference level by configuring a comparator inside a DSP for implementing the method of the invention, or generating a reference level by an external reference power supply and an external operational amplifier, and limiting a current threshold I wave by wavelimCorresponding to the reference level. Wave-by-wave current limiting threshold IlimThe specific correspondence with the reference level depends on hardware parameters and requirements for overcurrent protection, etc. In one embodiment of the present invention, the reference levels are 1.5V and 2.5V, respectively corresponding wave-by-wave current limiting threshold IlimNegative peak-50A and positive peak 50A.
In one embodiment of the invention, the transfer function of the PI regulator is:
wherein, KpIs a proportionality coefficient, KIIs an integration coefficient.
The PR regulator is a 1, 3, 5 and 7 th harmonic PR regulator, and plays a main role in carrying out PR control on high-order harmonics such as 3, 5 and 7, and the transfer function of the PR regulator is as follows:
wherein, KprIs a proportionality coefficient, KrIs the resonance coefficient, wckTo cut-off frequency, wkK is the harmonic order for the resonant frequency.
As shown in fig. 2, in the embodiment of the present invention, the PI regulator branch is connected in parallel with the PR regulator branch, and the PR regulator branch is provided with a switch K1, where K1 is a controllable switch and is controlled by software.
The control unit 40 may control the switch K1 to close when the condition for triggering the wave-by-wave current limiting is not met, so as to control the PR regulator to be switched in, and the PI regulator and the PR regulator work together to control the DC/AC conversion. Specifically, the output result of the PI regulator and the output result of the PR regulator may be added, the added sum is input to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
The control unit 40 may control the switch K1 to open to control the PR regulator to switch off when a condition triggering the ripple-by-ripple current limit is reached, i.e. entering the ripple-by-ripple current limit mode of operation, and only the PI regulator acts to control the DC/AC conversion. Specifically, the output result of the PI regulator may be input to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
According to the DC/AC control device in the off-grid mode of the bidirectional direct current charger, whether the condition of triggering wave-by-wave current limiting is met is judged, when the condition of triggering wave-by-wave current limiting is not met, the voltage difference value is adjusted through the PI adjuster and the PR adjuster, DC/AC conversion control is carried out according to the output result of the PI adjuster and the output result of the PR adjuster, when the condition of triggering wave-by-wave current limiting is met, the voltage difference value is adjusted through the PI adjuster, DC/AC conversion control is carried out according to the output result of the PI adjuster, therefore, the harmonic content of alternating current output voltage can be reduced when the bidirectional direct current charger is in an off-grid mode with non-linear load, current oscillation caused by shaking of the alternating current output voltage when wave-by-wave current limiting is acted can be avoided, and the probability of triggering hardware overcurrent protection is reduced, therefore, the load carrying capacity of the bidirectional direct current charger in an off-grid mode is improved.
Further, as shown in fig. 4, a clipping module may be connected to a branch of the PR adjuster, and the control unit 40 may perform clipping on an output result of the PR adjuster when the condition of triggering wave-by-wave current limiting is not met, add the output result of the PI adjuster and the clipped output result of the PR adjuster, input the added sum value to the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module. The limiting value can be set through a limited number of experiments according to actual control requirements, and is not limited to a specific value here. By limiting the output of the PR regulator, jitter of the output ac voltage can be further effectively suppressed.
In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (8)
1. A DC/AC control method of a bidirectional direct current charger in an off-grid mode is characterized in that the bidirectional direct current charger comprises a first conversion module and a second conversion module, when the bidirectional direct current charger works in the off-grid mode, direct current of a vehicle-end battery is subjected to DCDC conversion through the second conversion module and is subjected to DC/AC conversion through the first conversion module to obtain alternating current to be supplied to an off-grid load, and the DC/AC control method comprises the following steps:
collecting the voltage of the alternating current output by DC/AC conversion;
obtaining a voltage difference value by subtracting the given voltage from the voltage of the alternating current;
judging whether a condition of triggering wave-by-wave current limiting is met;
if the condition of triggering wave-by-wave current limiting is not met, the voltage difference value is regulated by a PI regulator and a PR regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator and the output result of the PR regulator;
if the condition of triggering wave-by-wave current limiting is reached, the voltage difference value is regulated by a PI regulator, and DC/AC conversion control is carried out according to the output result of the PI regulator,
performing DC/AC conversion control according to the output result of the PI regulator and the output result of the PR regulator, specifically comprising: and adding the output result of the PI regulator and the output result of the PR regulator, inputting the sum obtained by adding into an SPWM module, and generating and outputting a corresponding SPWM signal by the SPWM module so as to control the first conversion module.
2. The DC/AC control method under the off-grid mode of the bidirectional direct current charger according to claim 1, wherein DC/AC conversion control is performed according to an output result of the PI regulator and an output result of the PR regulator, and further comprising:
and carrying out amplitude limiting on the output result of the PR regulator, adding the output result of the PI regulator and the output result of the PR regulator after amplitude limiting, inputting the sum obtained by adding into an SPWM module, and generating and outputting a corresponding SPWM signal by the SPWM module so as to control the first conversion module.
3. The DC/AC control method in the off-grid mode of the bidirectional direct current charger according to claim 1 or 2, characterized in that the PR regulator is controlled to be cut off and connected by controlling the opening and closing of a switch of a branch where the PR regulator is located.
4. The DC/AC control method in the off-grid mode of the bidirectional direct current charger according to claim 3, wherein the PR regulator is a 1, 3, 5, 7 th harmonic PR regulator, and a transfer function of the PR regulator is as follows:
wherein, KprIs a proportionality coefficient, KrIs the resonance coefficient, wckTo cut-off frequency, wkK is the harmonic order for the resonant frequency.
5. The DC/AC control method of the bidirectional direct-current charger in the off-grid mode according to claim 4, wherein a condition of triggering the wave-by-wave current limiting is judged by judging whether the current of the off-grid load reaches a wave-by-wave current limiting threshold value.
6. The utility model provides a DC/AC controlling means under two-way direct current charger off-grid mode which characterized in that, two-way direct current charger includes first conversion module and second conversion module, when two-way direct current charger work in off-grid mode, the direct current of car end battery carries out DCDC conversion through the second conversion module, and carry out DC/AC conversion through the first conversion module, obtains the alternating current in order to provide for off-grid load, DC/AC controlling means includes:
the voltage acquisition unit is used for acquiring the voltage of the alternating current output by DC/AC conversion;
the difference value calculating unit is used for calculating the difference between the given voltage and the voltage of the alternating current to obtain a voltage difference value;
the judging unit is used for judging whether the condition of triggering wave-by-wave current limiting is achieved or not;
a control unit, which is used for adjusting the voltage difference value through a PI adjuster and a PR adjuster when the condition of triggering wave-by-wave current limiting is not reached, and carrying out DC/AC conversion control according to the output result of the PI adjuster and the output result of the PR adjuster, adjusting the voltage difference value through the PI adjuster when the condition of triggering wave-by-wave current limiting is reached, and carrying out DC/AC conversion control according to the output result of the PI adjuster,
the control unit is specifically used for adding the output result of the PI regulator and the output result of the PR regulator when the condition of triggering wave-by-wave current limiting is not reached, inputting the added sum value into the SPWM module, the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module, and when the condition of triggering wave-by-wave current limiting is reached, the output result of the PI regulator is input into the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
7. The DC/AC control device under the off-grid mode of the bidirectional direct-current charger according to claim 6, wherein the control unit is further configured to clip the output result of the PR regulator when a condition of triggering wave-by-wave current limiting is not met, add the output result of the PI regulator and the output result of the PR regulator after clipping, input the added sum value into the SPWM module, and the SPWM module generates and outputs a corresponding SPWM signal to control the first conversion module.
8. The DC/AC control device of the bidirectional direct current charger in the off-grid mode according to claim 6 or 7, wherein the control unit controls the PR regulator to be cut off and connected by controlling the opening and closing of a switch of a branch where the PR regulator is located.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011507024.8A CN112713796B (en) | 2020-12-18 | 2020-12-18 | DC/AC control method and device of bidirectional direct current charger in off-grid mode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011507024.8A CN112713796B (en) | 2020-12-18 | 2020-12-18 | DC/AC control method and device of bidirectional direct current charger in off-grid mode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112713796A CN112713796A (en) | 2021-04-27 |
| CN112713796B true CN112713796B (en) | 2022-05-17 |
Family
ID=75544848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011507024.8A Active CN112713796B (en) | 2020-12-18 | 2020-12-18 | DC/AC control method and device of bidirectional direct current charger in off-grid mode |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112713796B (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110112780A (en) * | 2019-05-16 | 2019-08-09 | 池州学院 | A kind of single-phase photovoltaic power generation dual mode inverter system and its control method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103138590B (en) * | 2011-12-02 | 2017-02-08 | 中兴通讯股份有限公司 | Current-limiting protection method and device of resonance circuit |
| CN103219705B (en) * | 2013-03-12 | 2016-02-24 | 中兴通讯股份有限公司 | The short-circuit protection method of half bridge resonant transformer and device |
| CN103199724B (en) * | 2013-04-24 | 2015-10-28 | 常熟开关制造有限公司(原常熟开关厂） | A kind of two-stage type photovoltaic DC-to-AC converter |
| KR101699174B1 (en) * | 2015-09-09 | 2017-01-23 | 한국전력공사 | Microgrid capable inverter device and method of controlling same |
| CN105471276A (en) * | 2015-12-24 | 2016-04-06 | 哈尔滨同为电气股份有限公司 | AC-AC converter control method suitable for suppressing alternating-current input harmonic |
| CN106849725A (en) * | 2016-11-25 | 2017-06-13 | 广西电网有限责任公司南宁供电局 | A kind of control method of single-phase off-network inverter |
| CN108539711B (en) * | 2018-04-10 | 2020-05-19 | 北京动力源新能源科技有限责任公司 | Wave-by-wave current-limiting protection method and device and motor controller |
| CN109600061B (en) * | 2019-01-10 | 2020-08-21 | 天津工业大学 | Novel fixed-frequency model prediction current control method based on dynamic weight |
-
2020
- 2020-12-18 CN CN202011507024.8A patent/CN112713796B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110112780A (en) * | 2019-05-16 | 2019-08-09 | 池州学院 | A kind of single-phase photovoltaic power generation dual mode inverter system and its control method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112713796A (en) | 2021-04-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109194113B (en) | Power factor corrector with active power decoupling function and control method thereof | |
| Wang et al. | Comprehensive topological analyses of isolated resonant converters in PEV battery charging applications | |
| JP5316514B2 (en) | Power converter | |
| CN115189578B (en) | CLLC converter control device and method for isolated bidirectional charger | |
| CN109327158B (en) | Current type grid-connected inverter integrating power decoupling and buck-boost functions | |
| CN110228376B (en) | High-voltage charging system of hydrogen fuel automobile and control system thereof | |
| US20110261597A1 (en) | Inverter type engine generator | |
| CN112491277A (en) | Method for improving efficiency of power electronic transformer through dead time self-adaption | |
| CN115313861A (en) | Control method based on two-stage bidirectional inverter parallel system | |
| Qiu et al. | An enhanced battery interface of MMC-BESS | |
| CN112713796B (en) | DC/AC control method and device of bidirectional direct current charger in off-grid mode | |
| Patil et al. | Comparative Study of Single-phase Power Factor Correction Topologies for Electric Vehicle Battery Charger Based on Boost Converter | |
| CN115021541A (en) | Method for suppressing pulse power of non-isolated UPQC circuit in off-network operation state | |
| Tang et al. | An improved burst-mode control for VIENNA rectifiers to mitigate DC voltage ripples at light load | |
| US11557972B2 (en) | Power conversion device | |
| CN116317499A (en) | Single-phase inverter based on flying capacitor type three-level boost and control method | |
| CN113098283B (en) | Control method of constant-frequency double-freedom-degree real-time calculation single-stage and single-phase rectifier | |
| CN113890406A (en) | Bridgeless single-stage isolation AC-DC converter and control method thereof | |
| CN113098313A (en) | Inversion feedback control circuit, control method and inverter | |
| CN113489293A (en) | Method for realizing secondary ripple current suppression of direct-current power supply through control | |
| Kanimozhi et al. | Battery charger for automotive applications | |
| Itoh et al. | Requirements for circuit components of single-phase inverter applied with power decoupling capability toward high power density | |
| Pichan et al. | Modelling and digital-based direct power control of shunt active power filter for rectifier loads | |
| Dabbagh et al. | A 5kW Bidirectional Isolated On-Board EV Battery Charger Using Hybrid PFC/Inverter | |
| CN214674881U (en) | Ripple current control device, circuit, charging device and vehicle |
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 | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: 213000 5-a201, chuangyangang, Changzhou science and Education City, No. 18, Changwu Middle Road, Wujin District, Changzhou City, Jiangsu Province Applicant after: Guochuang mobile energy innovation center (Jiangsu) Co.,Ltd. Address before: Room 354, No. 18, Xinya Road, Wujin high tech Industrial Development Zone, Changzhou City, Jiangsu Province Applicant before: National innovation energy automobile intelligent energy equipment innovation center (Jiangsu) Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |