CN113064018A - Direct current charging pile metering detection circuit, device and method - Google Patents
Direct current charging pile metering detection circuit, device and method Download PDFInfo
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G—PHYSICS
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- 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
- G01R22/10—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods using digital techniques
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
Abstract
The invention discloses a direct current charging pile metering detection circuit, a device and a method thereof, wherein the circuit comprises: the device comprises a power supply socket, a direct current zero-flux transformer, a resistor, a switch unit, a charging socket, a battery pack, a resistor voltage division network, a direct current electric energy acquisition circuit, an interface simulator, a switch control coil, a chip peripheral and a power supply module; the power supply socket is connected with the charging socket through the direct-current zero-flux mutual inductor and the switch unit, and the battery pack is connected with the charging socket; the direct current zero magnetic flux mutual inductor is connected with the chip and the chip peripheral through a resistor and a direct current electric energy acquisition circuit; the resistance voltage-dividing network is connected with the direct-current zero-flux transformer in parallel and is connected with the direct-current electric energy acquisition circuit; the switch unit is connected with the chip and the chip peripheral through the switch control coil and the interface simulator. The invention can realize the active power error detection of charging and reverse charging of the charging pile, and adopts a proper correction mode to prolong the service life of the battery.
Description
Technical Field
The invention relates to the technical field of charging pile detection, in particular to a direct current charging pile metering detection circuit, a direct current charging pile metering detection device and a direct current charging pile metering detection method.
Background
As a leading industry in the new state of national economy, the new energy electric automobile industry needs support of numerous public charging facilities for future large-scale development of electric automobiles, but along with the large-scale market entry of off-board direct-current charging piles, a high-capacity direct-current charger adopting a high-power direct-current charging technology is about to emerge continuously, and therefore detection of the off-board direct-current charging piles is more and more important.
However, in the mainstream enterprises in the market, such as XL-942 off-board charger field characteristic tester of shenzhen xinglong science and technology limited company, TD1320 electric vehicle charger field tester of changshan constant measurement and control technology limited company, and the like, generally adopt resistive loads, and can only detect forward active power errors, but cannot detect reverse active power of reversely charged charging piles.
Disclosure of Invention
The invention aims to provide a metering detection circuit, a metering detection device and a metering detection method for a direct-current charging pile, so that charging active power error detection of the charging pile and reverse charging active power error detection of the charging pile are realized, a 20% excess correction mode is used, the battery is guaranteed to work between 30-70% of electric quantity, and the charging and discharging times of the battery are improved.
In order to achieve the above object, an embodiment of the present invention provides a metering and detecting circuit for a dc charging pile, including: the device comprises a power supply socket, a direct current zero-flux transformer, a resistor, a switch unit, a charging socket, a battery pack, a resistor voltage division network, a direct current electric energy acquisition circuit, an interface simulator, a switch control coil, a chip and a chip peripheral device;
the power supply socket is connected with the charging socket through the direct-current zero-flux mutual inductor and the switch unit, and the battery pack is connected with the charging socket;
the direct current zero magnetic flux mutual inductor is connected with the chip and the chip peripheral through the resistor and the direct current electric energy acquisition circuit;
the resistance voltage division network is connected with the direct current zero magnetic flux mutual inductor in parallel and is connected with the direct current electric energy acquisition circuit;
the switch unit is connected with the chip and the chip peripheral through the switch control coil and the interface simulator.
In one embodiment, the display device further comprises a display screen, a keyboard and a first power converter, wherein the display screen, the keyboard and the first power converter are respectively connected with the chip and the chip peripheral.
In one embodiment, the direct current charging pile metering detection circuit is characterized in that the direct current electric energy acquisition circuit comprises an AD converter, a voltage dividing resistor, a reference voltage chip, an input matching resistor Ra1, an input matching resistor Ra2 and a second power converter;
the REF pin of the AD converter is connected with the reference voltage chip;
the voltage dividing resistor comprises a voltage dividing resistor R1 and a voltage dividing resistor R2, the input end of the voltage dividing resistor is connected with the REF pin of the AD converter, and the output end of the voltage dividing resistor is connected with the second ADC pin of the AD converter;
the input matching resistor Ra1 is connected with a first ADC pin of the AD converter, and the input matching resistor Ra2 is connected with a second ADC pin of the AD converter;
the second power converter is connected with VCC and VLogic pins of the AD converter.
The invention also provides a direct current charging pile metering and detecting device which is characterized by comprising the direct current charging pile metering and detecting circuit.
The invention also provides a direct current charging pile metering and detecting method, which is applied to the direct current charging pile metering and detecting device and is characterized by comprising the following steps:
controlling the interface simulator to close the switch of the switch unit;
judging the voltage collected by the direct current electric energy collecting circuit;
when the voltage is greater than a preset threshold value, controlling an interface simulator to simulate the charging state of a charging pile on a battery pack, collecting discrete sampling values of charging current and charging voltage generated during charging, and calculating a charging direct current active electric energy error, wherein the charging direct current active electric energy error is displayed through a display screen for detection;
and when the voltage is less than or equal to a preset threshold value, controlling an interface simulator to simulate the reverse charging state of the charging pile by the battery pack, and collecting discrete sampling values of reverse charging current and reverse charging voltage generated in the reverse charging process, wherein the direction of the reverse charging current is opposite, the discrete sampling value of the reverse charging current is negative, calculating the charging direct current active electric energy error, and displaying the charging direct current active electric energy error through a display screen for detection.
In one embodiment, the method for calculating the charging dc active power error includes:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*VIi×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein, PiIs instantaneous active power, Ts is sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the electric pile of charging of artifical reading, and Ep is active electric energy.
In one embodiment, the method for calculating the reverse charging dc active power error includes:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*(-VIi)×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein Ts is a sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the charging pile that is read manually.
In one embodiment, the method further comprises the step of setting a currently detected charging current value of the charging pile or a currently detected reverse charging current value of the charging pile in reverse charging according to a keyboard.
In one embodiment, the method further comprises setting the charging degree during charging or the charging degree during reverse charging according to a 20% increment mode.
In one embodiment, the preset threshold comprises 373V.
According to the direct current charging pile metering detection circuit, the direct current charging pile metering detection device and the direct current charging pile metering detection method, charging active electric energy error detection of the charging pile and reverse charging active electric energy error detection of the charging pile are achieved, a 20% excess correction mode is used, the battery is guaranteed to work between 30% and 70% of electric quantity, charging and discharging times of the battery are improved, and the service life of the battery is prolonged.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a dc charging pile metering and detecting circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a dc charging pile metering and detecting circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a dc electric energy collection circuit of the dc charging pile metering and detecting circuit according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of a dc charging pile metering and detecting method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, 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" indicate the presence of the described 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 term "and/or" refers to and includes any and all possible combinations of one or more of the associated listed items.
Referring to fig. 1-2, an embodiment of the invention provides a dc charging pile metering and detecting circuit 100, including: the system comprises a power supply socket 10, a direct current zero-flux transformer 20, a resistor 60, a switch unit 30, a charging socket 40, a battery pack 50, a resistor voltage-dividing network 70, a direct current energy collecting circuit 80, an interface simulator 101, a switch control coil 90 and a chip and chip peripheral device 102;
the power supply socket 10 is connected with the charging socket 40 through the direct current zero-flux transformer 20 and the switch unit 30, and the battery pack 50 is connected with the charging socket 40;
the direct current zero magnetic flux transformer 20 is connected with the chip and the chip peripheral 102 through a resistor 60 and a direct current energy acquisition circuit 80;
the resistance voltage division network 70 is connected with the direct current zero magnetic flux transformer 20 in parallel, and the resistance voltage division network 70 is connected with the direct current electric energy acquisition circuit 80;
the switch unit 30 is connected to the chip and the chip peripheral 102 via the switch control coil 90 and the interface simulator 101.
In this embodiment, the dc charging pile metering and detecting circuit 100 is composed of a dc power supply socket 10, a dc charging socket 40, a power module, a dc zero-flux transformer 20, a resistor voltage dividing network 70, a dc power collecting circuit 80, an electric vehicle interface simulator 101, a BF609 chip and chip peripheral 102, a keyboard KEY, a display LCD, a first power converter, switches K1 and K2 of a switch unit 30, a battery pack 50, and a resistor 60. The direct current power supply socket 10 is a socket of a direct current loop connected to the direct current charging pile 40 in series; the power supply module adopts +/-15V and 5V output switch small power supplies, and the current is output by 2A; the direct-current zero-flux transformer 20 adopts an LEM IT200-S company, the maximum output is 250A, 200A:200mA, and the transformation ratio is 1000: 1; the resistor 60 is a 0.01% precision resistor of 5 Ω; the low-voltage arm divider resistor R2 of the resistor divider network 70 is a 0.01% precision resistor of 2K, and the high-voltage arm divider resistor R1 is a 0.01% precision resistor of 998K, which constitutes a dc voltage sensor transformation ratio of 1000:2, i.e., 500: 1; the BF609 chip and the chip peripheral device 102 are composed of a BF609 chip and a chip peripheral device of ADI company, a large number of peripheral devices are arranged in the chip, the chip comprises 2 SPI interfaces, 3 SPORT ports, AMC interfaces (asynchronous storage interfaces) and the like, 256MBYTE DRAM, a real-time clock, a network port and the like, the BF609 chip and the chip peripheral device 102 are used for completing the metering algorithm, task scheduling, displaying and inputting of the invention and communicating with the electric automobile interface simulator 101 through the network port, more than 16 general IO ports are used, and 6 IO ports are used for keyboard input; the electric automobile interface simulator 101 is an XL-A632 electric automobile interface simulator of Shenzhen Xinglong science and technology Limited, and can complete interface communication and time sequence simulation of an electric automobile. The charging protocol of the electric automobile is simulated through the CAN bus, the communication is carried out through the network port, the BF609 chip and the chip peripheral device 102, and a relay is arranged for controlling the opening and closing of the switches K1 and K2 in the switch unit 30; battery pack 50, battery with a customized battery pack 50 capacity of 50 degrees 350V, maximum charging current: 250A; the switches K1, K2 in the switch unit 30 are 250A dc contactors, rated operating voltage: DC 750V, rated operating current: 300A, operating voltage of the switching control coil 90: DC 12V-15V.
In one embodiment, the display device further comprises a display screen, a keyboard and a first power converter, wherein the display screen, the keyboard and the first power converter are respectively connected with the chip and the chip peripheral.
In the embodiment, in the direct current charging pile metering and detecting circuit 100, the display screen LCD is a dot-matrix simple liquid crystal display module, is directly driven by the BF609 chip and the AMC of the chip peripheral 102, and is used for displaying electric energy, electric parameters, and the like; the keyboard is a simple keyboard, and 6 keyboards in total are input to 6 IOs of the BF609 chip and the chip peripheral 102 and are used for setting the charging current of the charging pile; the first power converter is a linear voltage stabilizing module converting 5V to 3.3V, converts a 5V power supply into 3.3V for BF609 and an AD converter, and converts the 3.3V power supply by using a chip REG1117F-3.3 with fixed voltage output.
In one embodiment, the direct current charging pile metering detection circuit is characterized in that the direct current electric energy acquisition circuit comprises an AD converter, a voltage dividing resistor, a reference voltage chip, an input matching resistor Ra1, an input matching resistor Ra2 and a second power converter;
the REF pin of the AD converter is connected with the reference voltage chip;
the voltage dividing resistor comprises a voltage dividing resistor R1 and a voltage dividing resistor R2, the input end of the voltage dividing resistor is connected with the REF pin of the AD converter, and the output end of the voltage dividing resistor is connected with the second ADC pin of the AD converter;
the input matching resistor Ra1 is connected with a first ADC pin of the AD converter, and the input matching resistor Ra2 is connected with a second ADC pin of the AD converter;
the second power converter is connected with VCC and VLogic pins of the AD converter.
Referring to fig. 3, in the present embodiment, the dc power collecting circuit 80 includes an AD conversion signal AD7380, an input matching resistor Ra1, an input matching resistor Ra2, a voltage dividing resistor R1, a voltage dividing resistor R2, a reference voltage ADR441B, and a second power converter of 5V to 3.3V.
The AD7380 is a core device, the AD digit is 16, the double-channel synchronous sampling, the fully differential analog input, the maximum sampling rate: 4MSPS, SNR typical value: 92.5dB, on-chip oversampling function, basic resolution enhancement function, INL (maximum) 2.0LSB, equivalent to 2/65536 ═ 0.003%. The requirements are fully met for a 0.2-level inspection device;
the resistor Ra1 and the resistor Rb1 are common chip resistors, the divider resistor R1 and the divider resistor R2 use 1ppm high-precision resistors, the accuracy is better than 0.01 percent, the R1 and the R2 are in a bridge principle, matching resistors with the proportion value of R1/R2 better than 0.005 percent can be selected by factory shipment, and the resistance values of the R1 and the R2 are the same;
ADR441B is the standard of temperature drift with output of 2.5V 3ppm, and completely meets the requirement of a detection device of 0.2 percent;
the AD7380 sampling rate is 10KHz, and R1 and R2 divide voltage to generate a signal of half of reference voltage for realizing bidirectional metering of direct current:
1) when the direct current is in a charging state: the input value of the AD7380 is VI, and the common mode voltage to the ground is 1.25V + VI;
2) when the direct current is in a reverse charging state: the input value of AD7380 is-VI, and the common mode voltage to ground is 1.25V-VI.
Wherein the value of VI is in the range of 0-1.25V.
The invention also provides a direct current charging pile metering and detecting device which is characterized by comprising the direct current charging pile metering and detecting circuit.
The invention also provides a direct current charging pile metering and detecting method, which is applied to the direct current charging pile metering and detecting device and is characterized by comprising the following steps:
controlling the interface simulator 101 to close the switch of the switch unit;
judging the voltage collected by the direct current electric energy collecting circuit 80;
when the voltage is greater than the preset threshold value, controlling the interface simulator 101 to simulate the charging state of the charging pile on the battery pack 50, collecting discrete sampling values of charging current and charging voltage generated during charging, and calculating a charging direct current active electric energy error, wherein the charging direct current active electric energy error is displayed through a display screen for detection;
when the voltage is smaller than or equal to a preset threshold value, the control interface simulator 101 simulates a reverse charging state of the charging pile by the battery pack, collects a reverse charging current generated during reverse charging and a discrete sampling value of reverse charging voltage, wherein the direction of the reverse charging current is opposite, the discrete sampling value of the reverse charging current is negative, calculates a charging direct current active electric energy error, and the charging direct current active electric energy error is displayed through a display screen for detection.
In the present embodiment, the dc zero-flux transformer 20 reduces the input voltage of the charging pile by 1000 times, outputs the reduced voltage to the shunt resistor 60, and converts the reduced voltage into the voltage signal VI, where the resistance of the resistor 60 is 5 ohms, and the impedance equivalent to the primary charging current is Iz ═ 5 ohms/(1000) ═ 0.005 ohms. The maximum value 250A of the primary charging current I is, then, the maximum voltage VI ═ Iz ═ I ═ 0.005 ohm ═ 250A ═ 1.25V.
The differential mode input range of the AD738 in the direct current electric energy collection current 80 is-2.5V (value of VI). The absolute input range VI + and VI-to-ground value is-0.1-2.6V.
When in the charging mode, the absolute input is 1.25V +1.25V ═ 2.5V, which meets the design requirement, and the differential mode input range is: 0-1.25V, which meets the design requirement;
when in the reverse charging mode, the absolute input is 1.25V-1.25V ═ 0V and meets the design requirement, and the differential mode input range is as follows: the minus 1.25V-0 meets the design requirement;
the voltage divider network 70 reduces the voltage of the charging voltage U of the charging pile by 500 times and outputs the reduced voltage to the dc power acquisition circuit 80. The ratio is Kv (998+2)/2 (500). When the maximum value of the primary charging voltage U is 1000V, the secondary output VU is 1000V/Kv or 1000V/500V/2V, and the input range of the AD7380 in the direct-current electric energy collection circuit is 0 to 2.5V, which satisfies the design requirement.
The resistive divider network 70 and the dc zero-flux transformer 80 convert the high voltage and the large current into a small voltage and input the small voltage to the analog input terminal of the dc power collecting circuit 80.
The BF609 chip and the chip peripheral device 102 read the sampling values of the voltage and the current of the direct current electric energy acquisition circuit 80 through the SPORT interface, calculate the active electric energy and display the active electric energy on the LCD10, and the resolution can achieve 5 bits (converted to kWh) after decimal. When the active electric energy error of the charging pile is detected, the BF609 chip and the chip peripheral device 102 simulate the charging state of the electric automobile by controlling the electric automobile interface simulator 101, so that the charging pile charges the battery pack 50, and charging current and charging voltage are generated.
When the reverse charging active electric energy error is detected, the BF609 chip and the chip peripheral device 102 simulate the reverse charging state of the electric automobile by controlling the electric automobile interface simulator 101, the battery pack 50 carries out charging pile reverse charging, the electric energy of the battery is reversely transmitted to a power grid, and reverse charging current and reverse charging voltage are generated.
Referring to fig. 4, specifically, 1) the BBF609 chip and the chip peripheral 102 close the switches K1 and K2 of the switch unit 30 through the electric vehicle interface simulator 101;
2) the BF609 chip and the chip peripheral device 102 collect the voltage of the battery through the direct current electric energy collecting circuit 80, judge the capacity of the battery, when the voltage of the battery is larger than a preset threshold value, firstly carry out the active electric energy test of the charging mode of the charging pile, enter the step 3A and the step 4A, otherwise, carry out the reverse charging active electric energy test of the charging mode of the charging pile, and enter the step 3B and the step 4B;
the battery capacity is about 50%, the requirement on the accuracy of the battery capacity is low, the requirement can be ensured to be 45-65%, and the requirement can be completely met by directly measuring the voltage.
Because the electric energy consumed by one-time detection point is about 1 degree and only occupies about 2 percent of the battery capacity.
3A) BF609 chip and chip peripheral 102 control electric automobile interface simulator 101 to simulate electric automobile charging state, and set charging current value I of current detection of charging pile through keyboardCharging device. And collecting direct current voltage and direct current, calculating the active electric energy error according to a calculation method of the charging direct current active electric energy error, and recording the active electric energy error by a detection person through a display screen.
When the electric quantity of battery is greater than 50%, fill electric pile charging error through the detection and fill electric pile 20% more than the electric energy that electric pile reverse charging error was filled in the detection, also be exactly 0.2 degree electric energy, can let a battery that is full of the 100% electric quantity like this, through many times charge after detecting, the adjustment battery charge volume is in the safe interval that charges of 30 ~ 70%, prolongs the life of battery package.
4a) BF609 chip and chip peripheral device 102 control electric automobile interface simulator 101 to simulate the reverse charging state of the electric automobile, and the reverse charging current value I of the current detection of the charging pile is set through a keyboardReverse charging. Normally setting the reverse charging degree, controlling the direct current electric energy acquisition circuit 80 by the BF609 chip and the chip peripheral device 102, acquiring direct current voltage and direct current, calculating the active electric energy error according to the calculation method of the reverse charging direct current active electric energy error, and providing the detection personnel to record the active electric energy error through the display screen。
Wherein, | IReverse charging|＝|ICharging deviceAnd the electric energy discharged in the opposite direction is 1 degree, which is 0.2 degree less than the charging 1.2 degree.
Therefore, after the electric quantity of the battery is detected for multiple times, the electric quantity of the battery is always kept in a charging safety range of 30-70%, and the service life of the battery is prolonged.
3b) BF609 chip and chip peripheral device 102 control electric automobile interface simulator 101 to simulate the reverse charging state of the electric automobile, and the reverse charging current value I of the current detection of the charging pile is set through a keyboardReverse charging. The reverse charging degree is set in a 20% increment mode, the BF609 chip and the chip peripheral device 102 control the direct current electric energy acquisition circuit 80 to acquire direct current voltage and direct current, calculate an active electric energy error according to a calculation method of a reverse charging direct current active electric energy error and provide the active electric energy error for a detection person to record through a display screen.
The 20% incremental mode calculation is consistent with step 3A). When the electric quantity of the battery is less than or equal to 50%, the electric energy which is 20% more than that charged by the charging pile is charged through the reverse charging of the charging pile, namely the electric energy of 0.2 degrees, so that the charging quantity of the battery with 0% of the electric quantity of the battery can be adjusted to be in a charging safety range of 30-70% after multiple charging detections.
4B) BF609 chip and chip peripheral device 102 control electric automobile interface simulator 101 to simulate electric automobile charging state, and set charging current value I of current detection of charging pile through keyboardCharging device。
Normally setting the charging degree, controlling the direct current electric energy acquisition circuit 80 by the BF609 chip and the chip peripheral device 102, acquiring direct current voltage and direct current, calculating an active electric energy error according to a calculation method of the charging direct current active electric energy error, and recording the active electric energy error by a detector through a display screen. The charging electric energy is 1 degree, which is 0.2 degree less than the discharging 1.2 degree. Therefore, the battery with the battery capacity of 0% can be kept in a charging safety range of 30-70% after multiple detections, and the service life of the battery is prolonged.
In one embodiment, the method for calculating the charging dc active power error includes:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*VIi×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein, PiIs instantaneous active power, Ts is sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the electric pile of charging of artifical reading, and Ep is active electric energy.
In this embodiment, the BF609 chip and the chip peripheral 102 simulate the charging state of the electric vehicle by controlling the electric vehicle interface simulator 101, so that the charging pile charges the battery pack 50 to generate a charging current and a charging voltage.
The transformation ratio of the resistance voltage-dividing network 70 is 500 Kv (voltage-dividing design of 500: 1), and the transformation ratio is input to the dc power collecting circuit to reduce the voltage once. When the transformation ratio of the dc zero current transformer is 1000 and the resistance of the resistor 60 is 5 ohms, the relative primary impedance Iz is 5/1000-0.005 ohms, and the transimpedance is input to the dc energy collecting circuit to perform primary current reduction.
When charging stake under the mode of charging:
the BF609 chip and the chip peripheral device 102 collect discrete sampling values of voltage and current through a direct current electric energy collecting circuit. Calculating the instantaneous active power after discretization, wherein the sampling rate is 10kHz, and the formula is as follows:
Pi＝VUi*VIi×Kv×Iz
wherein Kv is 500; iz is 0.005; i is a sampling point; VIiThe current of the ith sampling point; VUiThe voltage at the ith sample point.
Calculating the active electric energy of the detection device:
the electric energy is the integral of power over time, and the integral is performed by using a dot product and a method, so that the formula for calculating the functional electric energy is as follows:
wherein, Ts is sampled at a time interval of 10KHz and 1s is 0.0001 s
Wherein n is the number of accumulated sampling points, i is the sampling point, and Ts is the time of the sampling interval. In Watts Seconds (WS).
At present, kilowatt-hour (kWh) is used for detection of a charging pile as a unit, and according to the display requirement of a 6.5 th charger of the JJJG 1149-2018 electric vehicle off-board charger verification regulation, the charger can display charging electric energy, unit price and payment amount, and the number of electric energy display digits is not less than 6 digits (at least comprises 3 decimal places). The unit of active electrical energy is converted to kWh as follows:
wherein n is the number of accumulated sampling points, i is a sampling point, Ts is the time of a sampling interval, and Ts is 0.0001 second; kv is 500; iz is 0.005; VUiThe input is converted primary voltage input into the direct current electric energy acquisition circuit; VIiThe input is converted for the primary current input into the direct current energy collecting circuit.
The electric energy indication value of the charging pile is three decimal places, and the unit is kWh. According to the b-item requirement of the work error measured according to 9.3.2 th of the verification procedure of the JJG1149-2018 electric vehicle off-board charger, a standard table and the detected charger (pile) run synchronously, and the ratio (%) of the electric energy value represented by the last digit (or the minimum graduation) of the display of the detected charger (pile) to the accumulated electric energy is not more than 1/10 of the grade index of the detected charger. Therefore, at least 1.000kWh of electricity is required to be charged for the first-level charging pile with the resolution of 0.001 kWh; a secondary charging post resolution of 0.001kWh requires at least 0.500kWh of power. If the electric quantity value of the charging pile is Ex, the active electric energy error is
Where Ep is represented by floating point, 6 bits after the decimal point.
In one embodiment, the method for calculating the reverse charging dc active power error includes:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*(-VIi)×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein Ts is a sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the charging pile that is read manually.
In this embodiment, the BF609 chip and the chip peripheral 102 simulate the reverse charging state of the electric vehicle by controlling the electric vehicle interface simulator 101, so that the battery pack 50 reversely charges the charging pile, and reversely transmits the electric energy of the battery to the power grid to generate a reverse charging current and a reverse charging voltage.
The transformation ratio of the resistance voltage-dividing network 70 is 500 Kv (voltage-dividing design of 500: 1), and the transformation ratio is input to the dc power collecting circuit to reduce the voltage once. When the transformation ratio of the dc zero current transformer is 1000 and the resistance of the resistor 60 is 5 ohms, the relative primary impedance Iz is 5/1000-0.005 ohms, and the transimpedance is input to the dc energy collecting circuit to perform primary current reduction.
When charging stake under the mode of charging:
the BF609 chip and the chip peripheral device 102 collect discrete sampling values of voltage and current through a direct current electric energy collecting circuit. And calculating the instantaneous active power after discretization, wherein the sampling rate is 10 kHz. In the reverse charging state, the direction of the current is reversed, the value is negative, the voltage is positive in the reverse charging mode, and the formula is as follows:
Pi＝VUi*(-VIi)×Kv×Iz
wherein Kv is 500; iz is 0.005; i is a sampling point; VIiThe current of the ith sampling point; VUiThe voltage at the ith sample point.
Calculating the active electric energy of the detection device:
the electric energy is the integral of power over time, and the integral is performed by using a dot product and a method, so that the formula for calculating the functional electric energy is as follows:
wherein, Ts is sampled at a time interval of 10KHz and 1s is 0.0001 s
Wherein n is the number of accumulated sampling points, i is the sampling point, and Ts is the time of the sampling interval. In Watts Seconds (WS).
At present, kilowatt-hour (kWh) is used for detection of a charging pile as a unit, and according to the display requirement of a 6.5 th charger of the JJJG 1149-2018 electric vehicle off-board charger verification regulation, the charger can display charging electric energy, unit price and payment amount, and the number of electric energy display digits is not less than 6 digits (at least comprises 3 decimal places). The unit of active electrical energy is converted to kWh as follows:
wherein n is the number of accumulated sampling points, i is a sampling point, Ts is the time of a sampling interval, and Ts is 0.0001 second; kv is 500; iz is 0.005; VUiThe input is converted primary voltage input into the direct current electric energy acquisition circuit; VIiThe input is converted for the primary current input into the direct current energy collecting circuit.
The electric energy indication value of the charging pile is three decimal places, and the unit is kWh. According to the b-item requirement of the work error measured according to 9.3.2 th of the verification procedure of the JJG1149-2018 electric vehicle off-board charger, a standard table and the detected charger (pile) run synchronously, and the ratio (%) of the electric energy value represented by the last digit (or the minimum graduation) of the display of the detected charger (pile) to the accumulated electric energy is not more than 1/10 of the grade index of the detected charger. Therefore, at least 1.000kWh of electricity is required to be charged for the first-level charging pile with the resolution of 0.001 kWh; a secondary charging post resolution of 0.001kWh requires at least 0.500kWh of power. If the electric quantity value of the charging pile is Ex, the active electric energy error is
Where Ep is represented by floating point, 6 bits after the decimal point.
In one embodiment, the method further comprises the step of setting a currently detected charging current value of the charging pile or a currently detected reverse charging current value of the charging pile in reverse charging according to a keyboard.
In the embodiment, the BF609 chip and the chip peripheral 102 collect discrete sampling values of voltage and current in a charging state or a reverse charging state through the dc power collecting circuit 80,
in one embodiment, the method further comprises setting the charging degree during charging or the charging degree during reverse charging according to a 20% increment mode.
In this embodiment, the charging degree needs to be set in a 20% increment mode, the BF609 chip and the chip peripheral 102 control the dc power collecting circuit 80, and the 20% increment mode is calculated as follows:
the accuracy of the current charging pile to be detected is assumed to be level 1. I.e. 1% accuracy. The active electric energy resolution of the charging pile is 0.001 degrees, and according to the requirements of the JJG1149-2018 electric vehicle off-board charger verification regulations, the ratio (%) of the electric energy value represented by the last-position straight line (or the minimum graduation) of the display of the detected charger to the accumulated electric energy is not more than 1/10 of the grade index of the detected charger. The charging post charges at least 1 degree of electricity and 1.2 degrees in 20% increments, the specification requirement is 1/10 no greater than the rating index, the formula is as follows:
wherein E is charging electric energy, the grade index of the charging pile is 0.01 (1-grade pile), the resolution of the charging pile is 0.001 degrees according to the regulation requirement, and the E is 1.2 degrees which is 0.2 degrees higher than the theoretical value of 1 degree; 0.001 is the electric energy display resolution of the charging pile; 0.01 is the accuracy grade of the charging pile; the ratio (%) of the accumulated electric energy should not be greater than 1/10 of the rating index of the battery to be tested.
In one embodiment, the preset threshold comprises 373V.
In this embodiment, the capacity of the battery is determined, and when the voltage of the battery is greater than 373V, an active power test of the charging mode of the charging pile is performed first. When the battery voltage is 373V, the battery capacity is about 50%
According to the direct current charging pile metering detection circuit, the direct current charging pile metering detection device and the direct current charging pile metering detection method, charging active electric energy error detection of the charging pile and reverse charging active electric energy error detection of the charging pile are achieved, a 20% excess correction mode is used, the battery is guaranteed to work between 30% and 70% of electric quantity, charging and discharging times of the battery are improved, and the service life of the battery is prolonged.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. The utility model provides a direct current fills electric pile measurement detection circuitry which characterized in that includes: the device comprises a power supply socket, a direct current zero-flux transformer, a resistor, a switch unit, a charging socket, a battery pack, a resistor voltage division network, a direct current electric energy acquisition circuit, an interface simulator, a switch control coil, a chip and a chip peripheral device;
the power supply socket is connected with the charging socket through the direct-current zero-flux mutual inductor and the switch unit, and the battery pack is connected with the charging socket;
the direct current zero magnetic flux mutual inductor is connected with the chip and the chip peripheral through the resistor and the direct current electric energy acquisition circuit;
the resistance voltage division network is connected with the direct current zero magnetic flux mutual inductor in parallel and is connected with the direct current electric energy acquisition circuit;
the switch unit is connected with the chip and the chip peripheral through the switch control coil and the interface simulator.
2. The direct current charging pile metering detection circuit according to claim 1, further comprising a display screen, a keyboard and a first power converter, wherein the display screen, the keyboard and the first power converter are respectively connected with the chip and a chip peripheral.
3. The direct current charging pile metering detection circuit of claim 1, wherein the direct current power acquisition circuit comprises an AD converter, a voltage division resistor, a reference voltage chip, an input matching resistor Ra1, an input matching resistor Ra2 and a second power converter;
the REF pin of the AD converter is connected with the reference voltage chip;
the voltage dividing resistor comprises a voltage dividing resistor R1 and a voltage dividing resistor R2, the input end of the voltage dividing resistor is connected with the REF pin of the AD converter, and the output end of the voltage dividing resistor is connected with the second ADC pin of the AD converter;
the input matching resistor Ra1 is connected with a first ADC pin of the AD converter, and the input matching resistor Ra2 is connected with a second ADC pin of the AD converter;
the second power converter is connected to VCC and Vlogic pins of the AD converter.
4. A metering and detecting device for a direct current charging pile is characterized by comprising the metering and detecting circuit for the direct current charging pile according to any one of claims 1 to 3.
5. A DC charging pile metering and detecting method is applied to the DC charging pile metering and detecting device of claim 4, and is characterized by comprising the following steps:
controlling the interface simulator to close the switch of the switch unit;
judging the voltage collected by the direct current electric energy collecting circuit;
when the voltage is greater than a preset threshold value, controlling an interface simulator to simulate the charging state of a charging pile on a battery pack, collecting discrete sampling values of charging current and charging voltage generated during charging, and calculating a charging direct current active electric energy error, wherein the charging direct current active electric energy error is displayed through a display screen for detection;
and when the voltage is less than or equal to a preset threshold value, controlling an interface simulator to simulate the reverse charging state of the charging pile by the battery pack, and collecting discrete sampling values of reverse charging current and reverse charging voltage generated in the reverse charging process, wherein the direction of the reverse charging current is opposite, the discrete sampling value of the reverse charging current is negative, calculating the charging direct current active electric energy error, and displaying the charging direct current active electric energy error through a display screen for detection.
6. The direct current charging pile metering detection method according to claim 5, wherein the method for calculating charging direct current active power error comprises the following steps:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*VIi×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein, PiIs instantaneous active power, Ts is sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the electric pile of charging of artifical reading, and Ep is active electric energy.
7. The direct current charging pile metering detection method according to claim 5, wherein the method for calculating the reverse charging direct current active power error comprises the following steps:
calculating the discretized instantaneous active power PiThe formula is as follows:
Pi＝VUi*(-VIi)×Kv×Iz
therein, VUiIs the voltage at the ith sampling point, VIiKv is the transformation ratio of the resistance voltage division network, and Iz is the relative primary impedance;
calculating the active electric energy Ep according to the instantaneous active power, wherein the formula is as follows:
wherein Ts is a sampling time interval;
calculating an active electric energy error Err% according to the active electric energy, wherein the formula is as follows:
wherein, Ex is the electric energy indicating value of the charging pile that is read manually.
8. The direct current charging pile metering and detecting method according to claim 5, characterized by further comprising setting a currently detected charging current value of the charging pile during charging or a currently detected reverse charging current value of the charging pile during reverse charging according to a keyboard.
9. The metering and detecting method for the direct current charging pile according to claim 5, characterized by further comprising the step of setting the charging degree during charging or the charging degree during reverse charging according to a 20% increment mode.
10. The direct current charging pile metering detection method according to claim 5, wherein the preset threshold comprises 373V.
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