CN115356557A - Method and system for evaluating charging and discharging loss of electric vehicle charger - Google Patents

Method and system for evaluating charging and discharging loss of electric vehicle charger Download PDF

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CN115356557A
CN115356557A CN202210938522.0A CN202210938522A CN115356557A CN 115356557 A CN115356557 A CN 115356557A CN 202210938522 A CN202210938522 A CN 202210938522A CN 115356557 A CN115356557 A CN 115356557A
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loss
battery
charging
discharge
charge
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王智
杨静
曾伟杰
刘谋海
王海元
郭光�
贺星
陈浩
申丽曼
曾文伟
苏玉萍
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State Grid Corp of China SGCC
State Grid Hunan Electric Power Co Ltd
Metering Center of State Grid Hunan Electric Power Co Ltd
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State Grid Corp of China SGCC
State Grid Hunan Electric Power Co Ltd
Metering Center of State Grid Hunan Electric Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/60—Monitoring or controlling charging stations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/60—Monitoring or controlling charging stations
    • B60L53/62—Monitoring or controlling charging stations in response to charging parameters, e.g. current, voltage or electrical charge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters
    • G01R22/06—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/386—Arrangements for measuring battery or accumulator variables using test-loads
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/04—Ageing analysis or optimisation against ageing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/06—Power analysis or power optimisation

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Abstract

The invention discloses an evaluation method and a system for the charging and discharging loss of an electric vehicle charger. The alternating current side current of the charger and the battery Soc state are introduced into the loss calculation of the battery as the parallel loss fusion weight, the positive correlation between different battery Soc states and operation loss and the positive correlation between the metering error of the electric energy meter and the charging current are considered, and the accuracy of the battery loss calculation is improved. The influence of the charging and discharging loss, the charging loss and the discharging loss of the battery is comprehensively considered when the charging and discharging loss of the charger is evaluated, the problem that the energy consumption evaluation one-sidedness is caused by only considering a single charging or discharging process in the existing means is solved, and the accuracy of an evaluation result is greatly improved.

Description

Method and system for evaluating charging and discharging loss of electric vehicle charger
Technical Field
The invention relates to the technical field of charger charging and discharging loss evaluation, in particular to an evaluation method and system for charging and discharging loss of an electric vehicle charger.
Background
With the low-carbon economy becoming the main melody of the economic development of China, the new energy strategy and the smart grid become an important direction for the development of the power industry, and automobiles, urban rail transit and the like in the form of direct-current power supply are increasingly widely applied to the national economy and social life. According to the national standard, the electric vehicle charging pile must be subjected to mandatory verification in 2023 years, and the development trend of the existing public charging pile mainly takes high-voltage large-current direct-current charging of a direct-current charger as a main trend.
The study of scholars at home and abroad shows that if the charging loss evaluation result of the charger has 1% deviation, the economic loss at the thousand yuan level can be caused to users or power companies, and the fairness of trade settlement is seriously influenced.
At present, a standard meter and a real power method and the like are often adopted to analyze the metering error of a charger, but the evaluation of the charging and discharging loss of the electric vehicle charger is limited by complicated field working conditions, the accuracy of an evaluation result is poor, and particularly when a field charging direct current signal has large ripple waves, the accuracy of the evaluation of the charging and discharging loss of the electric vehicle is low.
Disclosure of Invention
The invention provides an evaluation method and system for charging and discharging loss of an electric vehicle charger, and aims to solve the technical problem that an evaluation result is poor in accuracy in the existing evaluation method for the charging and discharging loss of an electric vehicle.
According to one aspect of the invention, the method for evaluating the charging and discharging loss of the electric vehicle charger comprises the following steps:
carrying out charging and discharging loss test experiments under different battery states, wherein each battery state corresponds to different alternating current input side currents, and optimizing the experimental configuration of battery input and output net electric energy by adjusting the size of an electronic load so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured by an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured by a direct current electric energy meter arranged on the direct current input side of the battery;
and measuring the loss of the battery in a charging and discharging loss test experiment, calculating a charging and discharging parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charging and discharging parallel loss factor.
Further, charge and discharge loss test experiments were performed in states where the batteries Soc were 20%, 40%, 60%, and 80%, respectively, each of which set the alternating input side currents of 10A, 30A, 50A, and 70A, respectively.
Further, the calculation formula of the net input and output electric energy of the battery is as follows:
C net ＝C in -C out
wherein, C net The net electric energy input by the battery is not more than 0.5kWh in Indicating battery input power, C out Indicating that the battery is discharging electrical energy,
Figure BDA0003784492510000021
Figure BDA0003784492510000022
I DC-in direct current representing battery charge, I DC-out Indicating the DC current of the battery discharge, N indicating the number of times the battery was charged and discharged, t i Indicates the start time of the i-th charge/discharge, t ci Represents the charging time interval of the i-th charge and discharge, t di Indicating the discharge time interval of the i-th charge and discharge.
Further, the calculation formula of the battery charge-discharge loss rate is as follows:
Figure BDA0003784492510000023
wherein R is C The charge-discharge loss rate is shown,it should not exceed 0.1%.
Further, the loss of the battery in the charge and discharge loss test experiment comprises charge and discharge round-trip loss, charge loss and discharge loss, wherein the calculation formula of the charge and discharge round-trip loss is as follows:
Figure BDA0003784492510000031
wherein L is io Represents charge and discharge round trip loss, M represents total state number of battery Soc in charge and discharge loss test experiment, K represents total charge and discharge round trip number in charge and discharge loss test experiment, and L io (k) Represents the charge-discharge round-trip loss recorded in the kth experiment, ave { } represents the calculated average value, I ch (k) Represents the ac input side current at the k-th experiment;
the calculation formula of the charging loss is as follows:
Figure BDA0003784492510000032
wherein L is ch Represents the charge loss, Q represents the total number of charges in the charge-discharge loss test experiment, L ch (q) represents the charge loss recorded in the kth experiment, I ch (q) represents an alternating input-side current at the time of the q-th experiment;
the formula for the discharge loss is:
Figure BDA0003784492510000033
wherein L is o Represents the discharge loss, R represents the total number of discharges in the test experiment of the discharge and discharge loss, L o (r) represents the discharge loss recorded in the r-th experiment, I ch (r) represents the ac input side current at the time of the r-th experiment.
Further, calculating a charge-discharge parallel loss factor of the electric vehicle charger according to the loss of the battery based on the following formula:
Figure BDA0003784492510000035
wherein F represents a charge-discharge parallel loss factor of the electric vehicle charger,
Figure BDA0003784492510000034
further, when F is equal to or more than 70%, the charge and discharge loss evaluation result is serious loss, when F is equal to or more than 50% and less than 70%, the charge and discharge loss evaluation result is high loss, when F is equal to or more than 30% and less than 50%, the charge and discharge loss evaluation result is normal, and when F is less than 30%, the charge and discharge loss evaluation result is low loss.
Further, the active accuracy of the alternating current electric energy meter is not lower than 2 levels, and the active accuracy of the direct current electric energy meter is not lower than 1 level.
Further, the maximum allowable voltage of the alternating current side of the electric vehicle charger is 240V, the maximum allowable current is 75A, and the maximum power is 18kW.
In addition, the invention also provides an evaluation system for the charge and discharge loss of the electric vehicle charger, which comprises the following steps:
the charging and discharging loss testing module is used for performing charging and discharging loss testing experiments under different battery states, each battery state corresponds to different alternating current input side currents respectively, and the experimental configuration of battery input and output net electric energy is optimized by adjusting the size of an electronic load, so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured through an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured through a direct current electric energy meter arranged on the direct current input side of the battery;
and the loss grade evaluation module is used for measuring the loss of the battery in a charge and discharge loss test experiment, calculating a charge and discharge parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charge and discharge parallel loss factor.
Further, the charge and discharge loss test module performs charge and discharge loss test experiments in states of 20%, 40%, 60% and 80% of the batteries Soc, respectively, each of which sets an alternating input side current of 10A, 30A, 50A and 70A, respectively.
Further, the charging and discharging loss testing module calculates the net input and output electric energy of the battery by adopting the following formula:
C net ＝C in -C out
wherein, C net Indicating that the net electric energy input by the battery is not more than 0.5kWh in Indicating battery input power, C out Indicating that the battery is discharging electrical energy,
Figure BDA0003784492510000041
Figure BDA0003784492510000042
I DC-in direct current representing battery charge, I DC-out Indicating the DC current at which the battery is discharged, N indicating the number of times the battery is charged and discharged, t i Indicates the starting time of the i-th charge/discharge, t ci Represents the charging time interval of the i-th charge and discharge, t di Indicating the discharge time interval of the i-th charge and discharge.
Further, the charging and discharging loss test module calculates the charging and discharging loss rate of the battery by adopting the following formula:
Figure BDA0003784492510000051
wherein R is C The charge/discharge loss ratio should not exceed 0.1%.
Further, the loss of the battery in the charge and discharge loss test experiment comprises charge and discharge round-trip loss, charge loss and discharge loss, wherein the calculation formula of the charge and discharge round-trip loss is as follows:
Figure BDA0003784492510000052
wherein L is io Represents charge and discharge round trip loss, M represents total state number of battery Soc in charge and discharge loss test experiment, K represents total charge and discharge round trip number in charge and discharge loss test experiment, and L io (k) Represents the charge-discharge round-trip loss recorded in the kth experiment, ave { } represents the calculated average value, I ch (k) Represents the ac input side current at the k-th experiment;
the calculation formula of the charging loss is as follows:
Figure BDA0003784492510000053
wherein L is ch Represents the charge loss, Q represents the total number of charges in the charge-discharge loss test experiment, L ch (q) represents the charge loss recorded in the k-th experiment, I ch (q) represents an alternating input-side current at the time of the q-th experiment;
the formula for the discharge loss is:
Figure BDA0003784492510000054
wherein L is o Represents the discharge loss, R represents the total number of discharges in the test experiment of the discharge and discharge loss, L o (r) represents the discharge loss recorded in the r-th experiment, I ch (r) represents the ac input side current at the r-th experiment.
Further, the loss grade evaluation module calculates a charge-discharge parallel loss factor of the electric vehicle charger according to the loss of the battery based on the following formula:
Figure BDA0003784492510000061
wherein F represents a charge-discharge parallel loss factor of the electric vehicle charger,
Figure BDA0003784492510000062
further, when F is equal to or more than 70%, the charge and discharge loss evaluation result is serious loss, when F is equal to or more than 50% and less than 70%, the charge and discharge loss evaluation result is high loss, when F is equal to or more than 30% and less than 50%, the charge and discharge loss evaluation result is normal, and when F is less than 30%, the charge and discharge loss evaluation result is low loss.
Further, the active accuracy of the alternating current electric energy meter is not lower than 2 grades, and the active accuracy of the direct current electric energy meter is not lower than 1 grade.
Further, the maximum allowable voltage of the alternating current side of the electric vehicle charger is 240V, the maximum allowable current is 75A, and the maximum power is 18kW.
The invention has the following effects:
according to the method for evaluating the charging and discharging loss of the electric vehicle charger, the charging and discharging loss test experiment is carried out in different battery states, each battery state is respectively corresponding to different alternating current input side currents to carry out the test experiment, the experiment configuration of inputting and outputting net electric energy of the battery is optimized by adjusting the size of the electronic load, the charging and discharging loss rate of the battery is not more than the preset threshold value, the interference caused by the charging and discharging loss of the battery in the charging and discharging loss evaluation process of the electric vehicle charger is greatly reduced, and the accuracy of the evaluation result is improved. Then, the alternating current side current of the charger and the battery Soc state are introduced into the loss calculation of the battery as a parallel loss fusion weight, the positive correlation between different battery Soc states and operation loss and the positive correlation between the electric energy meter metering error and the charging current are considered, and the accuracy of the battery loss calculation is improved. And finally, evaluating the loss grade of the electric vehicle charger according to the calculated charge-discharge parallel loss factor, and comprehensively considering the influences of the charge-discharge loss, the charge loss and the discharge loss of the battery when evaluating the charge-discharge loss of the charger, so that the problem of one-sidedness evaluation of energy consumption in the single charge or discharge process only by the existing means is solved, and the accuracy of the evaluation result is greatly improved.
In addition, the system for evaluating the charging and discharging loss of the electric vehicle charger also has the advantages.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic flow chart of a method for evaluating a charging and discharging loss of an electric vehicle charger according to a preferred embodiment of the present invention.
Fig. 2 is a schematic diagram of a circuit connection structure for performing a charge and discharge loss test experiment in the preferred embodiment of the present invention.
Fig. 3 is a schematic structural diagram of an evaluation system for charge and discharge loss of an electric vehicle charger according to another embodiment of the invention.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be practiced in many different ways, which are defined and covered by the following.
As shown in fig. 1, a preferred embodiment of the present invention provides a method for evaluating a charging and discharging loss of an electric vehicle charger, including the following steps:
step S1: carrying out charging and discharging loss test experiments under different battery states, wherein each battery state corresponds to different alternating current input side currents respectively, and optimizing the experiment configuration of battery input and output net electric energy by adjusting the size of an electronic load so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured through an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured through a direct current electric energy meter arranged on the direct current input side of the battery;
step S2: and measuring the loss of the battery in a charging and discharging loss test experiment, calculating a charging and discharging parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charging and discharging parallel loss factor.
It can be understood that, in the method for evaluating the charging and discharging loss of the electric vehicle charger according to the embodiment, the charging and discharging loss test experiment is performed in different battery states, each battery state is respectively corresponding to different alternating current input side currents to perform the test experiment, and the experiment configuration of the battery input and output net electric energy is optimized by adjusting the size of the electronic load, so that the charging and discharging loss rate of the battery does not exceed the preset threshold value, the interference caused by the charging and discharging loss of the battery in the charging and discharging loss evaluation process of the electric vehicle charger is greatly reduced, and the accuracy of the evaluation result is improved. Then, the alternating current side current of the charger and the battery Soc state are introduced into the loss calculation of the battery as a parallel loss fusion weight, the positive correlation between different battery Soc states and operation loss and the positive correlation between the electric energy meter metering error and the charging current are considered, and the accuracy of the battery loss calculation is improved. And finally, estimating the loss grade of the electric vehicle charger according to the calculated charge-discharge parallel loss factor, and comprehensively considering the influences of the charge-discharge loss, the charge loss and the discharge loss of the battery when estimating the charge-discharge loss of the charger, overcoming the problem that the energy consumption estimation is only carried out in a single charging or discharging process by the existing means, and greatly improving the accuracy of the estimation result.
It CAN be understood that, as shown in fig. 2, the electric vehicle charger converts the ac power of the power distribution network into dc power and outputs the dc power to the electric vehicle battery pack, the ac side of the electric vehicle charger is connected to the ac power distribution network through the circuit breaker, the circuit breaker has a breaking capacity of ac 100A, the maximum allowable voltage of the ac side of the electric vehicle charger is 240V, the maximum allowable current is 75A, and the maximum allowable power is 18kW, and a J1772 connector is provided for communication with the CAN bus. The battery pack of the electric automobile is formed by connecting battery pack modules in series, the output voltage is between 100V and 400V, the capacity is between 50 and 200Ah, and the battery pack comprises 48 LiPF6 modules which are connected in series, the output voltage is 345V, and the capacity is 106 Ah. The electronic load is connected with the output end of the battery pack of the electric automobile, and the discharge current of the battery pack and the Soc state of the battery can be changed by adjusting the power of the electronic load. In the step S1, an ac electric energy meter is disposed on an ac input side of a charger of the electric vehicle, so that the magnitude of the ac side current input into the charger can be monitored in real time, and a dc electric energy meter is disposed on a dc input side of the battery, so that the magnitude of the dc charging current of the battery can be monitored in real time. The active accuracy of the alternating current electric energy meter is not lower than 2 levels, and the active accuracy of the direct current electric energy meter is not lower than 1 level. Optionally, the alternating current electric energy meter selects DDS102 of win group, the active accuracy is 1 level, the current specification is 5 (60) a, the voltage specification is 220V, the direct current electric energy meter selects a DJSF1352 electronic type direct current electric energy meter of An Kerui electric power company limited, the active accuracy is 1 level, and the voltage specification is 100-1000V.
It can be understood that, in the step S1, the charge and discharge loss test experiment is performed in different battery states, and each battery state corresponds to a different ac input side current, where a specific charge and discharge loss test experiment process belongs to the prior art, and is not described herein again. Alternatively, charge and discharge loss test experiments were performed in states where the batteries Soc were 20%, 40%, 60%, and 80%, respectively, each of which set the alternating input side currents of 10A, 30A, 50A, and 70A, respectively. And then, optimizing the experimental configuration of the input and output net electric energy of the battery by adjusting the power of the electronic load, so that the charge-discharge loss rate of the battery does not exceed a preset threshold value. The preset threshold is preferably 0.1%, and in other embodiments of the present invention, the preset threshold may also be set to 0.15%, 0.2%, 0.25%, and the like, and may be set as needed, which is not limited herein. The calculation formula of the net electric energy input and output by the battery is as follows:
C net ＝C in -C out
wherein, C net Represents electricityInputting net electric energy into the pool, wherein the net electric energy is not more than 0.5kWh in Representing the battery input power, representing the power injected into the battery of the electric vehicle from the grid, C out Indicating that the battery is discharging electrical energy,
Figure BDA0003784492510000091
I DC-in the direct current representing the charging of the battery is read out by a direct current meter, I DC-out The direct current representing the discharge of the battery can be directly read by an electronic load, N represents the number of times of charging and discharging the battery, t i Indicates the start time of the i-th charge/discharge, t ci Represents the charging time interval of the i-th charge and discharge, t di Represents the discharge time interval of the i-th charge and discharge.
In addition, the calculation formula of the battery charge-discharge loss rate is as follows:
Figure BDA0003784492510000092
wherein R is C The charge/discharge loss ratio should not exceed 0.1%.
The method can be understood that the charge and discharge loss test experiment is carried out under different battery states, each battery state is respectively corresponding to different alternating current input side currents to carry out the test experiment, and the experiment configuration of the input and output net electric energy of the battery is optimized by adjusting the size of the electronic load, so that the charge and discharge loss rate of the battery is not more than 0.1%, the interference caused by the charge and discharge loss of the battery in the charge and discharge loss evaluation process of the electric vehicle charger is greatly reduced, and the accuracy of the evaluation result is improved.
It is understood that, in the step S2, the loss of the battery in the charge and discharge loss test experiment includes charge and discharge round trip loss, charge loss and discharge loss, wherein the charge and discharge round trip loss is calculated by the following formula:
Figure BDA0003784492510000101
wherein L is io Represents charge and discharge round trip loss, M represents total state number of battery Soc in charge and discharge loss test experiment, K represents total charge and discharge round trip number in charge and discharge loss test experiment, and L io (k) Represents the charge-discharge round-trip loss recorded in the kth experiment, ave { } represents the calculated average value, I ch (k) Represents the ac input side current at the k-th experiment;
the calculation formula of the charging loss is as follows:
Figure BDA0003784492510000102
wherein L is ch Represents the charge loss, Q represents the total number of charges in the charge-discharge loss test experiment, L ch (q) represents the charge loss recorded in the kth experiment, I ch (q) represents an alternating input-side current at the time of the q-th experiment;
the formula for the discharge loss is:
Figure BDA0003784492510000103
wherein L is o Represents the discharge loss, R represents the total number of discharges in the test experiment of the discharge and discharge loss, L o (r) represents the discharge loss recorded in the r-th experiment, I ch (r) represents the ac input side current at the time of the r-th experiment.
Wherein the values of K, Q and R generally take the same value.
The method and the device have the advantages that the alternating-current side current of the charger and the battery Soc state are innovatively introduced into the loss calculation of the battery as the parallel loss fusion weight, the positive correlation between different battery Soc states and operation loss and the positive correlation between the metering error of the electric energy meter and the charging current are considered, and the accuracy of the battery loss calculation is improved.
In addition, the charge-discharge parallel loss factor of the electric vehicle charger is calculated according to the loss of the battery based on the following formula:
Figure BDA0003784492510000111
wherein F represents a charge-discharge parallel loss factor of the electric vehicle charger,
Figure BDA0003784492510000112
when F is more than or equal to 70%, the charge and discharge loss evaluation result is serious loss, when F is more than or equal to 50% and less than 70%, the charge and discharge loss evaluation result is high loss, when F is more than or equal to 30% and less than 50%, the charge and discharge loss evaluation result is normal, and when F is less than 30%, the charge and discharge loss evaluation result is low loss. The method and the device can be understood that the influence of the charging and discharging loss, the charging loss and the discharging loss of the battery is comprehensively considered when the charging and discharging loss of the charger is evaluated, the problem that the energy consumption evaluation one-sidedness is only considered in a single charging or discharging process in the existing means is solved, and the accuracy of an evaluation result is greatly improved.
For example, in one embodiment of the present invention, the correspondence relationship between the charge/discharge round trip loss of the electric vehicle battery, the battery state, and the ac side current, which is experimentally recorded, is shown in table 1:
TABLE 1, corresponding relation table of charge and discharge round trip loss of battery, battery state and AC side current
Figure BDA0003784492510000113
The correspondence relationship between the charging loss of the electric vehicle battery, the battery state, and the ac side current is shown in table 2:
TABLE 2, TABLE of correspondence between battery charging loss, battery state, and AC-side current
Figure BDA0003784492510000114
Figure BDA0003784492510000121
The correspondence relationship between the discharge loss of the electric vehicle battery, the battery state, and the ac side current is shown in table 3:
TABLE 3 corresponding relationship table of discharge loss of battery, battery state and AC side current
Figure BDA0003784492510000122
The weighted fusion results of the charge-discharge round-trip loss, the charge loss and the discharge loss of the battery are respectively as follows: l is io ＝0.1288，L ch ＝0.1105，L o =0.4749 where K, Q, R has the same value, all 4. And further calculating to obtain the loss-variable distance of the weighted fusion result of the charge-discharge round-trip loss and the charge loss and the discharge loss, normalizing, and calculating to obtain a charge-discharge loss grade factor of the electric vehicle charger, wherein the result is F =0.380537489. Since 50 percent>F is more than or equal to 30 percent, so the evaluation result of the charging and discharging loss of the electric vehicle charger is normal.
Example two
In addition, as shown in fig. 3, another embodiment of the present invention further provides an evaluation system for charging and discharging loss of an electric vehicle charger, which preferably adopts the above evaluation method for charging and discharging loss of an electric vehicle charger, and the system includes:
the charging and discharging loss testing module is used for performing charging and discharging loss testing experiments under different battery states, each battery state corresponds to different alternating current input side currents respectively, and the experimental configuration of battery input and output net electric energy is optimized by adjusting the size of an electronic load, so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured through an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured through a direct current electric energy meter arranged on the direct current input side of the battery;
and the loss grade evaluation module is used for measuring the loss of the battery in a charging and discharging loss test experiment, calculating a charging and discharging parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charging and discharging parallel loss factor.
It can be understood that, the evaluation system for the charging and discharging loss of the electric vehicle charger of the embodiment performs the charging and discharging loss test experiment in different battery states, each battery state corresponds to different alternating current input side currents respectively to perform the test experiment, and the experimental configuration of the battery input and output net electric energy is optimized by adjusting the size of the electronic load, so that the charging and discharging loss rate of the battery does not exceed the preset threshold value, the interference caused by the charging and discharging loss of the battery in the charging and discharging loss evaluation process of the electric vehicle charger is greatly reduced, and the accuracy of the evaluation result is improved. Then, the alternating-current side current of the charger and the battery Soc state are taken as parallel loss fusion weights and introduced into the loss calculation of the battery, the positive correlation between different battery Soc states and operation loss and the positive correlation between the electric energy meter metering error and the charging current are considered, and the accuracy of the battery loss calculation is improved. And finally, evaluating the loss grade of the electric vehicle charger according to the calculated charge-discharge parallel loss factor, and comprehensively considering the influences of the charge-discharge loss, the charge loss and the discharge loss of the battery when evaluating the charge-discharge loss of the charger, so that the problem of one-sidedness evaluation of energy consumption in the single charge or discharge process only by the existing means is solved, and the accuracy of the evaluation result is greatly improved.
It is understood that the charge and discharge loss test module performs charge and discharge loss test experiments in the states of 20%, 40%, 60% and 80% of the batteries Soc, respectively, each of which sets the ac input side current of 10A, 30A, 50A and 70A, respectively.
It can be understood that the charging and discharging loss test module calculates the net electric energy input and output by the battery by adopting the following formula:
C net ＝C in -C out
wherein, C net The net electric energy input by the battery is not more than 0.5kWh in Indicating battery input power, C out Indicating that the battery is discharging electrical energy,
Figure BDA0003784492510000131
Figure BDA0003784492510000141
I DC-in direct current representing battery charge, I DC-out Indicating the DC current of the battery discharge, N indicating the number of times the battery was charged and discharged, t i Indicates the starting time of the i-th charge/discharge, t ci Represents the charging time interval of the i-th charge and discharge, t di Represents the discharge time interval of the i-th charge and discharge.
It can be understood that the charging and discharging loss test module calculates the charging and discharging loss rate of the battery by adopting the following formula:
Figure BDA0003784492510000142
wherein R is C The charge/discharge loss ratio should not exceed 0.1%.
It can be understood that the loss of the battery in the charge and discharge loss test experiment includes charge and discharge round trip loss, charge loss and discharge loss, wherein the calculation formula of the charge and discharge round trip loss is as follows:
Figure BDA0003784492510000143
wherein L is io Represents charge and discharge round trip loss, M represents total state number of battery Soc in charge and discharge loss test experiment, K represents total charge and discharge round trip number in charge and discharge loss test experiment, and L io (k) Represents the charge-discharge round-trip loss recorded in the kth experiment, ave { } represents the calculated average value, I ch (k) Represents the ac input side current at the k-th experiment;
the charge loss is calculated by the formula:
Figure BDA0003784492510000144
wherein L is ch Represents the charge loss, Q represents the total number of charges in the charge-discharge loss test experiment, L ch (q) represents the charge loss recorded in the k-th experiment, I ch (q) represents an alternating input-side current at the time of the q-th experiment;
the formula for the discharge loss is:
Figure BDA0003784492510000151
wherein L is o Represents discharge loss, R represents total number of discharges in the test experiment of charge and discharge loss, and L o (r) represents the discharge loss recorded in the r-th experiment, I ch (r) represents the ac input side current at the time of the r-th experiment.
It can be understood that the loss level evaluation module calculates the charge-discharge parallel loss factor of the charger of the electric vehicle according to the loss of the battery based on the following formula:
Figure BDA0003784492510000152
wherein F represents a charge-discharge parallel loss factor of the electric vehicle charger,
Figure BDA0003784492510000153
wherein, when F is more than or equal to 70%, the charge and discharge loss evaluation result is serious loss, when F is more than or equal to 50% and less than 70%, the charge and discharge loss evaluation result is high loss, when F is more than or equal to 30% and less than 50%, the charge and discharge loss evaluation result is normal, and when F is less than 30%, the charge and discharge loss evaluation result is low loss.
It can be understood that the active accuracy of the ac electric energy meter is not lower than level 2, and the active accuracy of the dc electric energy meter is not lower than level 1.
It can be understood that the maximum allowable voltage of the alternating current side of the charger of the electric vehicle is 240V, the maximum allowable current is 75A, and the maximum power is 18kW.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (10)

1. The method for evaluating the charging and discharging loss of the electric vehicle charger is characterized by comprising the following steps of:
carrying out charging and discharging loss test experiments under different battery states, wherein each battery state corresponds to different alternating current input side currents, and optimizing the experimental configuration of battery input and output net electric energy by adjusting the size of an electronic load so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured by an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured by a direct current electric energy meter arranged on the direct current input side of the battery;
and measuring the loss of the battery in a charge and discharge loss test experiment, calculating a charge and discharge parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charge and discharge parallel loss factor.
2. The method for evaluating the charging and discharging loss of the charger of the electric vehicle according to claim 1, wherein the charging and discharging loss test experiments are respectively performed in states of 20%, 40%, 60% and 80% of the batteries Soc, and each state of the batteries Soc is respectively provided with an alternating input side current of 10A, 30A, 50A and 70A.
3. The method for evaluating the charging and discharging loss of the electric vehicle charger according to claim 1, wherein the calculation formula of the net energy input and output by the battery is as follows:
C net ＝C in -C out
wherein, C net Indicating that the net electric energy input by the battery is not more than 0.5kWh in Indicating battery input power, C out Indicating that the battery is discharging electrical energy,
Figure FDA0003784492500000011
Figure FDA0003784492500000012
I DC-in direct current representing battery charge, I DC-out Indicating the DC current of the battery discharge, N indicating the number of times the battery was charged and discharged, t i Indicates the starting time of the i-th charge/discharge, t ci Represents the charging time interval, t, of the ith charge and discharge di Represents the discharge time interval of the i-th charge and discharge.
4. The method for evaluating the charging and discharging loss of the electric vehicle charger according to claim 3, wherein the calculation formula of the battery charging and discharging loss rate is as follows:
Figure FDA0003784492500000021
wherein R is C The charge/discharge loss ratio should not exceed 0.1%.
5. The method for evaluating the charging and discharging loss of the electric vehicle charger according to claim 1, wherein the loss of the battery in the charging and discharging loss test experiment comprises a charging and discharging round trip loss, a charging loss and a discharging loss, wherein the charging and discharging round trip loss is calculated according to the following formula:
Figure FDA0003784492500000022
wherein L is io Represents charge and discharge round trip loss, M represents total state number of battery Soc in charge and discharge loss test experiment, K represents total charge and discharge round trip number in charge and discharge loss test experiment, and L io (k) Represents the charge-discharge round-trip loss recorded in the kth experiment, ave { } represents the calculated average value, I ch (k) Represents the ac input side current at the k-th experiment;
the calculation formula of the charging loss is as follows:
Figure FDA0003784492500000023
wherein L is ch Represents the charge loss, Q represents the total number of charges in the charge-discharge loss test experiment, L ch (q) represents the charge loss recorded in the k-th experiment, I ch (q) represents an alternating input-side current at the time of the q-th experiment;
the formula for the discharge loss is:
Figure FDA0003784492500000024
wherein L is o Represents the discharge loss, and R represents the charge-discharge loss testTotal number of discharges in the experiment, L o (r) represents the discharge loss recorded in the r-th experiment, I ch (r) represents the ac input side current at the time of the r-th experiment.
6. The method for evaluating the charging and discharging loss of the electric vehicle charger according to claim 5, wherein the charging and discharging parallel loss factor of the electric vehicle charger is calculated according to the loss of the battery based on the following formula:
Figure FDA0003784492500000031
wherein F represents the charge-discharge parallel loss factor of the electric vehicle charger,
Figure FDA0003784492500000032
7. the method for evaluating the charging and discharging loss of the charger of the electric vehicle according to claim 6, wherein the charging and discharging loss evaluation result is serious loss when F is more than or equal to 70%, high loss when F is more than or equal to 50% and less than 70%, normal when F is more than or equal to 30% and less than 50%, and low loss when F is less than 30%.
8. The method for evaluating the charging and discharging loss of the charger of the electric vehicle according to claim 1, wherein the active accuracy of the alternating current electric energy meter is not lower than 2 levels, and the active accuracy of the direct current electric energy meter is not lower than 1 level.
9. The method for evaluating the charging and discharging loss of the electric vehicle charger according to claim 1, wherein the maximum allowable voltage of the alternating current side of the electric vehicle charger is 240V, the maximum allowable current is 75A, and the maximum power is 18kW.
10. The utility model provides an evaluation system of electric automobile charger charge-discharge loss which characterized in that includes:
the charging and discharging loss testing module is used for performing charging and discharging loss testing experiments in different battery states, each battery state corresponds to different alternating current input side currents respectively, and the experimental configuration of battery input and output net electric energy is optimized by adjusting the size of an electronic load, so that the charging and discharging loss rate of the battery does not exceed a preset threshold value, wherein the alternating current input side currents are measured through an alternating current electric energy meter arranged on the alternating current input side of a charger of the electric vehicle, and the direct current charging currents of the battery are measured through a direct current electric energy meter arranged on the direct current input side of the battery;
and the loss grade evaluation module is used for measuring the loss of the battery in a charge and discharge loss test experiment, calculating a charge and discharge parallel loss factor of the electric vehicle charger according to the loss of the battery, and evaluating the loss grade of the electric vehicle charger according to the calculated charge and discharge parallel loss factor.
CN202210938522.0A 2022-08-05 2022-08-05 Method and system for evaluating charging and discharging loss of electric vehicle charger Pending CN115356557A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115648996A (en) * 2022-12-02 2023-01-31 广东蚂蚁金谷能源科技有限公司 Automobile charging device with intelligent power distribution function

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115648996A (en) * 2022-12-02 2023-01-31 广东蚂蚁金谷能源科技有限公司 Automobile charging device with intelligent power distribution function
CN115648996B (en) * 2022-12-02 2023-08-08 广东蚂蚁金谷能源科技有限公司 Automobile charging device with intelligent power distribution function

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