CN113922692B - Method for improving overall efficiency in two-stage bidirectional DCAC converter - Google Patents
Method for improving overall efficiency in two-stage bidirectional DCAC converter Download PDFInfo
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- CN113922692B CN113922692B CN202111212182.5A CN202111212182A CN113922692B CN 113922692 B CN113922692 B CN 113922692B CN 202111212182 A CN202111212182 A CN 202111212182A CN 113922692 B CN113922692 B CN 113922692B
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 230000002457 bidirectional effect Effects 0.000 title claims abstract description 24
- 230000001105 regulatory effect Effects 0.000 claims description 8
- HEZMWWAKWCSUCB-PHDIDXHHSA-N (3R,4R)-3,4-dihydroxycyclohexa-1,5-diene-1-carboxylic acid Chemical compound O[C@@H]1C=CC(C(O)=O)=C[C@H]1O HEZMWWAKWCSUCB-PHDIDXHHSA-N 0.000 claims description 6
- 230000008901 benefit Effects 0.000 abstract description 4
- 230000006872 improvement Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003094 perturbing effect Effects 0.000 description 1
Classifications
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
- H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
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- 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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
-
- 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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
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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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
-
- 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
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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- 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
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a method for improving the efficiency of a whole machine in a two-stage bidirectional DCAC converter, which comprises the following steps: setting a voltage disturbance formula of the voltage of the direct current bus; starting from 0, increasing a preset disturbance value each time, and calculating and storing a DC bus voltage set value and a complete machine efficiency value each time until the DC bus voltage set value is more than or equal to the maximum voltage in the range; and selecting a direct current bus voltage set value corresponding to the highest overall efficiency value from the stored plurality of direct current bus voltage set values, and taking the direct current bus voltage set value as a final direct current bus voltage set value. According to the invention, the DC bus voltage set value is continuously disturbed according to the different voltages of the battery side, and the DC bus voltage set value with the highest overall efficiency value is selected, so that the system can be ensured to be in the optimal efficiency during operation, the loss is reduced, and the energy utilization rate and the economic benefit are improved.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a method for improving the overall efficiency of a two-stage bidirectional DCAC converter.
Background
As shown in fig. 1, the existing two-stage bidirectional DCAC converter system has a DCDC Buck Boost circuit at the front stage and a DCAC inverter circuit at the rear stage, and is suitable for PCS (energy storage converter), V2G (Vehicle-to-grid), direct current sources, and the like, and is particularly widely used in gradient batteries. Specifically, the DCDC low voltage side is connected to a battery or dc load, the high voltage side is a dc bus and is connected to the DCAC dc side, and the DCAC ac side is connected to a grid or ac load.
At present, the system completely decouples functions to realize own functions respectively, and control is relatively simple, but due to the existence of two-stage power conversion, how to improve system efficiency and circuit reliability is a key problem in research. In the traditional control of the system, under the grid-connected condition, the direct current bus voltage is controlled by the DCAC; in the case of no grid, the dc bus voltage is controlled by DCDC. Because the overall efficiency of the system can be different along with the different direct current bus voltages, in order to achieve the purpose of ensuring energy bidirectional flow while achieving optimal efficiency, the direct current bus voltage value Vbusset needs to be continuously adjusted. In the case of a determined hardware filter inductance, capacitance and switching frequency, the existing method for adjusting the bus voltage is generally to directly set the bus voltage to a fixed value, or simply follow the battery voltage linearly through the battery voltage value Vbat on the direct current side (i.e., vbuset=vbat/k). However, neither of these methods currently optimize the overall efficiency of the system.
Therefore, improvements in the prior art are needed to increase the overall efficiency of the system.
The above information is presented as background information only to aid in the understanding of the present disclosure and is not intended or admitted to be prior art relative to the present disclosure.
Disclosure of Invention
The invention provides a method for improving the overall efficiency of a two-stage bidirectional DCAC converter, which aims to solve the defects in the prior art.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for improving overall efficiency in a two-stage bi-directional DCAC converter, the method comprising:
setting a voltage disturbance formula of the DC bus voltage as Vbus set=Vbat/k+b according to the requirement that the minimum voltage in the battery side voltage, the duty ratio and the DC bus voltage range is required to be larger than the DCAC minimum bus voltage; wherein, vbusset is a direct current bus voltage set value, vbat is battery side voltage, k is a fixed parameter, and b is an adjusting factor;
judging whether the operation is initial operation or not;
if not, adding a preset disturbance value to the regulating factor each time, and calculating and storing the set value of the DC bus voltage and the efficiency value of the whole machine each time until the set value of the DC bus voltage is larger than or equal to the maximum voltage in the DC bus voltage range;
if yes, the regulating factor is set to be 0, the DC bus voltage set value is set to be the minimum voltage in the DC bus voltage range for operation, then a preset disturbance value is added to the regulating factor each time, and the DC bus voltage set value and the overall efficiency value of each time are calculated and stored until the DC bus voltage set value is more than or equal to the maximum voltage in the DC bus voltage range;
and selecting a direct current bus voltage set value corresponding to the highest overall efficiency value from a plurality of stored direct current bus voltage set values, and taking the direct current bus voltage set value as a final direct current bus voltage set value.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, before the step of setting the voltage disturbance formula of the dc bus voltage to vbusset=vbat/k+b according to the requirement that the battery side voltage, the duty cycle and the minimum voltage in the dc bus voltage range need to be greater than the minimum bus voltage of the DCAC, the method further includes:
judging whether the variation of the battery side voltage is larger than a preset voltage value or not;
if yes, updating a disturbance direct current bus voltage set value, and executing the step of setting a voltage disturbance formula of direct current bus voltage as Vbus set=Vbat/k+b according to the requirement that the minimum voltage in the battery side voltage, the duty cycle and the direct current bus voltage range is required to be larger than the DCAC minimum bus voltage;
if not, the perturbed DC bus voltage set point does not need to be updated.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the step of calculating and storing the dc bus voltage set value and the overall efficiency value each time includes:
calculating the DC bus voltage set value each time according to Vbusset=Vbat/k+b;
acquiring battery side voltage, battery side current, power grid voltage and power grid current, and calculating the efficiency value of the whole machine each time;
and storing the DC bus voltage set value and the overall efficiency value obtained by each calculation.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the step of obtaining the battery side voltage, the battery side current, the grid voltage and the grid current and calculating the overall efficiency value of each time includes:
acquiring a battery side voltage and a battery side current, and calculating a first power;
acquiring power grid voltage and power grid current, and calculating second power;
and calculating the efficiency value of the whole machine each time through the first power and the second power.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the step of obtaining the battery side voltage and the battery side current and calculating the first power includes:
acquiring a battery side voltage and a battery side current acquired by DCDC;
a first power is calculated from the battery side voltage and the battery side current.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the step of obtaining the grid voltage and the grid current and calculating the second power includes:
acquiring a power grid voltage and a power grid current acquired by DCAC;
and calculating second power according to the grid voltage and the grid current.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, k is 0.95.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the preset disturbance value is 5V.
Further, in the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, the preset voltage value is 10V.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
according to the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, provided by the embodiment of the invention, the set value of the voltage of the direct current bus is continuously disturbed according to the difference of the voltages of the battery sides, and the set value of the voltage of the direct current bus with the highest overall efficiency value is selected, so that the system can be ensured to be in the optimal efficiency during operation, the loss is reduced, and the utilization rate of energy sources and the economic benefit are improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a circuit topology diagram of a prior art two-stage bi-directional DCAC converter system;
fig. 2 is a schematic flow chart of a method for improving overall efficiency in a two-stage bidirectional DCAC converter according to an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions of 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 apparent that the embodiments described below are only some embodiments of the present invention, not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it will be understood that when one component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present.
Furthermore, the terms "long," "short," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship based on that shown in the drawings, for convenience of description of the present invention, and are not intended to indicate or imply that the apparatus or elements referred to must have this particular orientation, operate in a particular orientation configuration, and thus should not be construed as limiting the invention.
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
Example 1
In view of the defects existing in the prior art, the inventor actively researches and innovates based on the rich practical experience and professional knowledge in the industry for many years and the application of the theory, so as to create a feasible whole machine efficiency improvement technology, and the technology has more practicability. After continuous research, design and repeated test and improvement, the invention with practical value is finally created.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for improving overall efficiency in a two-stage bidirectional DCAC converter according to an embodiment of the present invention, where the method is applicable to a scenario where overall efficiency is desired to be improved, and the method may be implemented by software and/or hardware. As shown in fig. 1, the method for improving the overall efficiency in the two-stage bidirectional DCAC converter may include the following steps:
s101, setting a voltage disturbance formula of the DC bus voltage as Vbus set=Vbat/k+b according to the requirement that the minimum voltage in the battery side voltage, the duty ratio and the DC bus voltage range is required to be larger than the DCAC minimum bus voltage; wherein VbusSet is a dc bus voltage set value, vbat is a battery side voltage, k is a fixed parameter, and b is an adjustment factor.
In this embodiment, k is 0.95.
It should be noted that, in this embodiment, it is set that, after the variation of the battery side voltage is greater than the preset voltage value, the dc bus voltage set value will enter the disturbance of the new cycle, so preferably, before the step S101, the method may further include:
judging whether the variation of the battery side voltage is larger than a preset voltage value or not;
if yes, the set value of the disturbance direct current bus voltage needs to be updated, and the step S101 is executed;
if not, the perturbed DC bus voltage set point does not need to be updated.
In this embodiment, the preset voltage value is 10V.
S102, judging whether the operation is initial operation or not; if yes, execute step S103, and execute step S104 again; if not, step S104 is directly performed.
S103, setting the regulating factor to 0, and setting the DC bus voltage set value to the minimum voltage operation in the DC bus voltage range.
And S104, adding a preset disturbance value to the regulating factor each time, and calculating and storing the set value of the DC bus voltage and the efficiency value of the whole machine each time until the set value of the DC bus voltage is larger than or equal to the maximum voltage in the DC bus voltage range.
In this embodiment, the preset disturbance value is 5V.
It should be noted that, in the above-mentioned series of steps, in the initial operation of the embodiment, the adjustment factor b will be assigned to 0, the dc bus voltage set value will be assigned to the minimum voltage operation in the dc bus voltage range, then the dc bus voltage set value is continuously disturbed, the dc bus voltage set value is increased by a preset disturbance value each time, that is, the adjustment factor b is increased by a preset disturbance value each time, after each disturbance, the disturbed dc bus voltage set value and the current overall efficiency value need to be stored until the dc bus voltage set value is greater than or equal to the maximum voltage in the dc bus voltage range, and then the disturbance is ended.
Preferably, the step of calculating and storing the dc bus voltage set point and the overall efficiency value each time may further include:
calculating the DC bus voltage set value each time according to Vbusset=Vbat/k+b;
acquiring battery side voltage, battery side current, power grid voltage and power grid current, and calculating the efficiency value of the whole machine each time;
and storing the DC bus voltage set value and the overall efficiency value obtained by each calculation.
Preferably, the step of obtaining the battery side voltage, the battery side current, the grid voltage and the grid current and calculating the efficiency value of the whole machine each time may further include:
acquiring a battery side voltage and a battery side current, and calculating a first power;
acquiring power grid voltage and power grid current, and calculating second power;
and calculating the efficiency value of the whole machine each time through the first power and the second power.
Preferably, the step of obtaining the battery side voltage and the battery side current and calculating the first power may further include:
acquiring a battery side voltage and a battery side current acquired by DCDC;
a first power is calculated from the battery side voltage and the battery side current.
Preferably, the step of obtaining the grid voltage and the grid current and calculating the second power may further include:
acquiring a power grid voltage and a power grid current acquired by DCAC;
and calculating second power according to the grid voltage and the grid current.
S105, selecting a direct current bus voltage set value corresponding to the highest overall efficiency value from a plurality of stored direct current bus voltage set values, and taking the direct current bus voltage set value as a final direct current bus voltage set value.
It should be noted that this step is to compare all dc bus voltage set values stored during the disturbance period, and pick out the dc bus voltage set value corresponding to the highest overall efficiency value from the dc bus voltage set values, so as to obtain the final most suitable dc bus voltage set value.
In order to prove the effectiveness of this embodiment, the embodiment is described with a specific example. In the system, the rated power of the selected two-stage system DCAC is 30kw, the set value of the DC bus voltage is increased by a preset disturbance value, namely 5V, and the DC side load power is controlled by 27kw, and the test result is shown in the following table:
it can be seen that from the actual operation result, the method of finding the optimal dc bus voltage set value by continuously perturbing the dc bus voltage set value is useful for improving the overall efficiency of the system.
According to the method for improving the overall efficiency in the two-stage bidirectional DCAC converter, provided by the embodiment of the invention, the set value of the voltage of the direct current bus is continuously disturbed according to the difference of the voltages of the battery sides, and the set value of the voltage of the direct current bus with the highest overall efficiency value is selected, so that the system can be ensured to be in the optimal efficiency during operation, the loss is reduced, and the utilization rate of energy sources and the economic benefit are improved.
The description of the foregoing embodiments has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to the particular embodiment, but, where applicable, may be interchanged and used with the selected embodiment even if not specifically shown or described. The same elements or features may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those skilled in the art. Numerous details are set forth, such as examples of specific parts, devices, and methods, in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to one skilled in the art that the exemplary embodiments may be embodied in many different forms without the use of specific details, and neither should be construed to limit the scope of the disclosure. In certain example embodiments, well-known processes, well-known device structures, and well-known techniques are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises" and "comprising" are inclusive and, therefore, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed and illustrated, unless specifically indicated. It should also be appreciated that additional or alternative steps may be employed.
When an element or layer is referred to as being "on," "engaged with," "connected to" or "coupled to" another element or layer, it can be directly on, engaged with, connected to or coupled to the other element or layer, or intervening elements or layers may also be present. In contrast, when an element or layer is referred to as being "directly on" … …, "" directly engaged with "… …," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship of elements should be interpreted in a similar manner (e.g., "between … …" and "directly between … …", "adjacent" and "directly adjacent", etc.). The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region or section from another element, component, region or section. Unless clearly indicated by the context, terms such as the terms "first," "second," and other numerical values are used herein to not imply a sequence or order. Accordingly, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as "inner," "outer," "below," "beneath," "lower," "above," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature's illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below" … … can encompass both upward and downward orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and interpreted in the relative description of the space herein.
Claims (7)
1. A method for improving overall efficiency in a two-stage bi-directional DCAC converter, the method comprising:
setting a voltage disturbance formula of the direct-current bus voltage as vbusset=vbat/k+b according to the requirements that the battery side voltage, the duty ratio and the minimum voltage in the direct-current bus voltage range are required to be larger than the minimum bus voltage of the two-stage bidirectional DCAC converter; wherein, vbusset is a direct current bus voltage set value, vbat is battery side voltage, k is a fixed parameter, and b is an adjusting factor;
judging whether the operation is initial operation or not;
if not, adding a preset disturbance value to the regulating factor each time, and calculating and storing the set value of the DC bus voltage and the efficiency value of the whole machine each time until the set value of the DC bus voltage is larger than or equal to the maximum voltage in the DC bus voltage range;
if yes, the regulating factor is set to be 0, the DC bus voltage set value is set to be the minimum voltage in the DC bus voltage range for operation, then a preset disturbance value is added to the regulating factor each time, and the DC bus voltage set value and the overall efficiency value of each time are calculated and stored until the DC bus voltage set value is greater than or equal to the maximum voltage in the DC bus voltage range;
selecting a direct current bus voltage set value corresponding to the highest overall efficiency value from a plurality of stored direct current bus voltage set values, and taking the direct current bus voltage set value as a final direct current bus voltage set value;
the step of calculating and storing the DC bus voltage set value and the overall efficiency value each time comprises the following steps:
calculating the DC bus voltage set value each time according to Vbusset=Vbat/k+b;
acquiring battery side voltage, battery side current, power grid voltage and power grid current, and calculating the efficiency value of the whole machine each time;
storing the DC bus voltage set value and the overall efficiency value obtained by each calculation;
the step of obtaining the battery side voltage, the battery side current, the power grid voltage and the power grid current and calculating the efficiency value of the whole machine each time comprises the following steps:
acquiring a battery side voltage and a battery side current, and calculating a first power;
acquiring power grid voltage and power grid current, and calculating second power;
and calculating the efficiency value of the whole machine each time through the first power and the second power.
2. The method for improving overall efficiency in a two-stage bidirectional DCAC converter according to claim 1, wherein before the step of setting a voltage disturbance formula of the dc bus voltage to vbusset=vbat/k+b according to a requirement that a minimum voltage in a battery side voltage, a duty cycle, and a dc bus voltage range needs to be greater than a minimum bus voltage of the two-stage bidirectional DCAC converter, the method further comprises:
judging whether the variation of the battery side voltage is larger than a preset voltage value or not;
if yes, the set value of the direct current bus voltage needs to be updated, and the step of setting a voltage disturbance formula of the direct current bus voltage to be Vbus set=Vbat/k+b according to the requirement that the minimum voltage in the voltage range of the direct current bus, the duty ratio and the battery side voltage is required to be larger than the minimum bus voltage of the two-stage bidirectional DCAC converter is executed;
if not, the DC bus voltage set value does not need to be updated.
3. The method for improving overall efficiency in a two-stage bi-directional DCAC converter as set forth in claim 1, wherein the steps of obtaining a battery side voltage and a battery side current and calculating a first power include:
acquiring battery side voltage and battery side current acquired by a DCDC circuit;
a first power is calculated from the battery side voltage and the battery side current.
4. The method for improving overall efficiency in a two-stage bi-directional DCAC converter as set forth in claim 1, wherein the steps of obtaining the grid voltage and the grid current, and calculating the second power include:
acquiring power grid voltage and power grid current acquired by a DCAC circuit;
and calculating second power according to the grid voltage and the grid current.
5. The method for improving overall efficiency in a two-stage bi-directional DCAC converter as set forth in claim 1, wherein k is 0.95.
6. The method for improving overall efficiency in a two-stage bi-directional DCAC converter as set forth in claim 1, wherein the preset disturbance value is 5V.
7. The method for improving overall efficiency in a two-stage bi-directional DCAC converter as set forth in claim 2, wherein the preset voltage value is 10V.
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| US20170117822A1 (en) * | 2015-10-23 | 2017-04-27 | Majid Pahlevaninezhad | Dynamic maximum efficiency tracker for pv micro-inverter |
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