Vehicle network interactive pulse charging method and system based on micro-grid simulation platform

Abstract

The invention provides a vehicle network interactive pulse charging method and system based on a micro-grid simulation platform. The method comprises the following steps: acquiring the current battery capacity, the required battery capacity, the vehicle taking time and the peak-valley electricity price time period of a vehicle; determining a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle taking time and the peak-valley electricity price period; obtaining the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determining an energy distribution strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period; and heating the battery, and then carrying out pulse charging on the battery of the vehicle based on the peak-valley charging time period, the energy distribution strategy and a preset fast charging strategy, or directly carrying out pulse charging. According to the scheme, the requirement for rapid charging of the electric vehicle in the low-temperature environment in application is met, and meanwhile the service life of the battery is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of electric vehicle charging, and in particular to a vehicle-grid interactive pulse charging method and system based on a microgrid simulation platform. Background Art

[0002] In severe cold weather, charging a battery at a reasonable rate is impossible or greatly shortens the battery life. For example, the biggest problem with charging lithium-ion batteries at low temperatures is lithium plating in the graphite negative electrode. The deposited lithium reacts rapidly with the electrolyte, resulting in irreversible capacity loss. In addition, metallic lithium grows in a dendritic form, which may penetrate the diaphragm and short-circuit the battery. In order to avoid lithium plating, lithium-ion batteries are charged at a very low rate at low temperatures, which takes a long time to complete the charging, which is very disadvantageous to the charging of electric vehicles. If lithium plating is not considered, the battery will be more damaged when charging at low temperatures. Therefore, it is urgent to propose a solution that can ensure battery life and fast charging at low temperatures. Summary of the invention

[0003] The present application provides a vehicle-grid interactive pulse charging method and system based on a microgrid simulation platform, so as to at least solve the technical problem that fast charging at low temperatures cannot guarantee the battery life.

[0004] The first embodiment of the present application proposes a vehicle-grid interactive pulse charging method based on a microgrid simulation platform, the method comprising:

[0005] Obtain the vehicle's current battery capacity, required battery capacity, vehicle pickup time, and peak and valley electricity price periods;

[0006] Determine a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time, and the peak-valley electricity price period;

[0007] Obtaining the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determining the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period;

[0008] During the peak-valley charging period, the temperature of the battery is monitored in real time, and it is determined whether to start the pulse heating strategy based on the temperature. If started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy. Otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

[0009] Preferably, determining the peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pickup time and the peak-valley electricity price period includes:

[0010] Determining the time required to charge the battery according to the current battery capacity, the required battery capacity, and the vehicle pickup time;

[0011] It is determined whether the battery can be charged during the valley price period according to the peak-valley electricity price period and the time required for charging. If so, charging is performed during the valley price period; otherwise, charging is started immediately.

[0012] Furthermore, the energy allocation strategy is determined according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak and valley charging period, including:

[0013] Determine the charging power and voltage of the battery at each moment according to the current battery capacity, the required battery capacity and the peak and valley charging time period;

[0014] Determine whether the voltage and power of the new energy power generation equipment at each moment correspond to the charging power and voltage of the battery at each moment. If so, use the voltage and power of the new energy power generation equipment at each moment as the energy allocation strategy. Otherwise, determine the difference between the voltage and power of the new energy power generation equipment at each moment and the charging power and voltage of the battery at each moment, and determine the energy allocation strategy based on the difference corresponding to each moment.

[0015] Furthermore, during the peak-valley charging period, the temperature of the battery is monitored in real time, and judging whether to start the pulse heating strategy according to the temperature includes:

[0016] It is determined whether the temperature of the battery is less than a low temperature threshold, and if so, the pulse heating strategy is started; otherwise, the pulse heating strategy is not started.

[0017] Furthermore, the pulse heating strategy includes:

[0018] Using a pulse current to heat the battery to a preset heating temperature switching threshold within a preset heating time;

[0019] Wherein, the preset heating time and the preset heating temperature switching threshold are determined by using a linear target weighting function;

[0020] The waveform of the pulse current is a bidirectional pulse waveform;

[0021] The bidirectional pulse waveform satisfies the formula I P ×T P =-I N ×T N, where I P is the positive pulse amplitude, T P is the duration of the positive pulse, I N is the reverse pulse amplitude, T N is the reverse pulse duration;

[0022] The positive and negative pulses of the bidirectional pulse waveform have a constant root mean square value of the current within one cycle;

[0023] The pulse current is a heating pulse current determined based on a pre-obtained optimal heating pulse period and a heating maximum pulse charging amplitude;

[0024] The fast charging strategy includes:

[0025] Determine the fast charge current based on the fast charge optimal pulse period and the fast charge maximum pulse charging amplitude obtained in advance;

[0026] The fast charging current is adjusted by using a PID control method to determine an initial charging current value;

[0027] Determining the charging current according to the initial charging current value and preset constraints;

[0028] pulse charging the battery based on the charging current;

[0029] Wherein, the preset constraint conditions include: charging current constraint and total power constraint;

[0030] The charging current constraint includes: the charging current of the battery is less than the maximum charging current multiple;

[0031] The total power constraint includes: the total charging power of the battery is less than or equal to the maximum total charging power.

[0032] Furthermore, the method further comprises:

[0033] When charging is performed based on a preset fast charging strategy, if the temperature of the battery is less than or equal to a preset heating temperature switching threshold, the preset pulse heating strategy is used to heat the temperature of the battery to the preset heating temperature switching threshold, and then the vehicle's battery is pulse charged based on the energy allocation strategy and the preset fast charging strategy.

[0034] Furthermore, the method further comprises:

[0035] The economy, durability and consistency of the battery charging process were evaluated.

[0036] The second embodiment of the present application proposes a vehicle-grid interactive pulse charging system based on a microgrid simulation platform, comprising:

[0037] The acquisition module is used to obtain the vehicle's current battery capacity, required battery capacity, vehicle pickup time, and peak and valley electricity price periods;

[0038] A first determination module is used to determine a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time and the peak-valley electricity price period;

[0039] The second determination module is used to obtain the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determine the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period;

[0040] The charging control module is used to monitor the temperature of the battery in real time during the peak-valley charging period, and determine whether to start the pulse heating strategy based on the temperature; if started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy; otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

[0041] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in the first aspect is implemented.

[0042] A fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect of the present application.

[0043] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0044] The present application proposes a vehicle-grid interactive pulse charging method and system based on a microgrid simulation platform, the method comprising: obtaining the current battery capacity, required battery capacity, vehicle pickup time, and peak-valley electricity price period of the vehicle; determining the peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pickup time, and the peak-valley electricity price period; obtaining the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determining the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity, and the peak-valley charging period; in the peak-valley charging period, real-time monitoring of the temperature of the battery, and judging whether to start the pulse heating strategy according to the temperature, if started, heating the temperature of the battery to a preset heating temperature switching threshold based on the pulse heating strategy, and then pulse charging the battery of the vehicle based on the peak-valley charging period, the energy allocation strategy, and the preset fast charging strategy, otherwise, directly pulse charging the battery of the vehicle based on the peak-valley charging period, the energy allocation strategy, and the preset fast charging strategy. The technical solution proposed in this application solves the need for rapid charging of electric vehicles in low-temperature environments, while ensuring the life of the battery.

[0045] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0047] Figure 1 A flow chart of a vehicle-grid interactive pulse charging method based on a microgrid simulation platform according to an embodiment of the present application;

[0048] Figure 2 A first structural diagram of a vehicle-grid interactive pulse charging system based on a microgrid simulation platform provided according to an embodiment of the present application;

[0049] Figure 3 A second structural diagram of a vehicle-grid interactive pulse charging system based on a microgrid simulation platform provided according to an embodiment of the present application;

[0050] Figure 4 A third structural diagram of a vehicle-grid interactive pulse charging system based on a microgrid simulation platform provided according to an embodiment of the present application;

[0051] Figure 5 A fourth structural diagram of a vehicle-grid interactive pulse charging system based on a microgrid simulation platform provided according to an embodiment of the present application;

[0052] Reference numerals

[0053] Electric vehicle power battery 1, V2G charging pile 2, MGCC communication module 3, first energy storage device 4, power distribution cabinet 5, PCS 6, DCDC 7, new energy power generation module 8, router 9, microgrid simulation platform 10, cluster module 10-1, strategy module 10-2, RS485 gateway 3-1, CAN gateway 3-2 and MGCC module 3-3. DETAILED DESCRIPTION

[0054] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0055] The present application proposes a vehicle-grid interactive pulse charging method and system based on a microgrid simulation platform, the method comprising: obtaining the current battery capacity, required battery capacity, vehicle pickup time, and peak-valley electricity price period of the vehicle; determining the peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pickup time, and the peak-valley electricity price period; obtaining the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determining the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity, and the peak-valley charging period; in the peak-valley charging period, real-time monitoring of the temperature of the battery, and judging whether to start the pulse heating strategy according to the temperature, if started, heating the temperature of the battery to a preset heating temperature switching threshold based on the pulse heating strategy, and then pulse charging the battery of the vehicle based on the peak-valley charging period, the energy allocation strategy, and the preset fast charging strategy, otherwise, directly pulse charging the battery of the vehicle based on the peak-valley charging period, the energy allocation strategy, and the preset fast charging strategy. The technical solution proposed in this application solves the need for rapid charging of electric vehicles in low-temperature environments, while ensuring the life of the battery.

[0056] The following describes a vehicle-grid interactive pulse charging method and system based on a microgrid simulation platform according to an embodiment of the present application with reference to the accompanying drawings.

[0057] Embodiment 1

[0058] Figure 1 Flow chart of a vehicle-grid interactive pulse charging method based on a microgrid simulation platform according to an embodiment of the present application, as shown in FIG. Figure 1 As shown, the method includes:

[0059] Step 1: Obtain the vehicle's current battery capacity, required battery capacity, vehicle pickup time, and peak and valley electricity price periods.

[0060] It should be noted that the user inserts the charging gun of the charging pile into the electric car to establish a connection between the charging pile and the electric car, and uses the charging pile by scanning the code through the mobile phone APP, entering the battery capacity of the charged vehicle, the SOC expected to be achieved when picking up the car, that is, the required battery capacity, and the time to pick up the car.

[0061] Step 2: Determine the peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time and the peak-valley electricity price period.

[0062] It should be noted that based on the principle of peak-valley arbitrage, it is judged whether the electricity price of the power grid is currently at a peak price or a valley price. At the same time, based on the power and voltage of the new energy power generation equipment, it is determined whether the electricity generated by the new energy equipment can meet the required battery capacity of the electric vehicle. If it does, the peak and valley electricity prices are not considered and power is supplied directly. Otherwise, the peak and valley charging periods are determined and charging is carried out during the peak and valley charging periods.

[0063] In the embodiment of the present disclosure, step 2 specifically includes:

[0064] 2-1: Determine the time required to charge the battery according to the current battery capacity, the required battery capacity, and the vehicle pick-up time;

[0065] 2-2: Determine whether the battery can be charged during the valley price period according to the peak-valley electricity price period and the time required for charging. If so, charge the battery during the valley price period; otherwise, start charging immediately.

[0066] Step 3: Obtain the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determine the energy allocation strategy based on the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period.

[0067] In the embodiment of the present disclosure, step 3 specifically includes:

[0068] 3-1: Determine the charging power and voltage of the battery at each time according to the current battery capacity, the required battery capacity and the peak and valley charging time period;

[0069] 3-2: Determine whether the voltage and power of the new energy power generation equipment at each moment correspond to the charging power and voltage of the battery at each moment. If so, use the voltage and power of the new energy power generation equipment at each moment as the energy allocation strategy. Otherwise, determine the difference between the voltage and power of the new energy power generation equipment at each moment and the charging power and voltage of the battery at each moment, and determine the energy allocation strategy based on the difference corresponding to each moment.

[0070] Step 4: During the peak-valley charging period, the temperature of the battery is monitored in real time, and whether to start the pulse heating strategy is determined based on the temperature. If started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy. Otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

[0071] In the embodiment of the present disclosure, step 4 specifically includes:

[0072] It is determined whether the temperature of the battery is less than a low temperature threshold, and if so, the pulse heating strategy is started; otherwise, the pulse heating strategy is not started.

[0073] It should be noted that when it is determined that the temperature of the current battery, i.e., the power battery, is lower than the low temperature threshold T0, low temperature heating is started, otherwise, the fast charging step is directly performed.

[0074] Further, the pulse heating strategy includes:

[0075] Using a pulse current to heat the battery to a preset heating temperature switching threshold within a preset heating time;

[0076] Wherein, the preset heating time and the preset heating temperature switching threshold are determined by using a linear target weighting function;

[0077] The waveform of the pulse current is a bidirectional pulse waveform;

[0078] The bidirectional pulse waveform satisfies the formula I P ×T P =-I N ×T N , that is, the algebraic sum of the time integrals of the positive and negative pulses of the bidirectional pulse waveform is 0, where I P is the positive pulse amplitude, T P is the duration of the positive pulse, I N is the reverse pulse amplitude, T N is the reverse pulse duration; since the depolarization effect of the resting interval is smaller than that of the reverse pulse and generates less heat, a bidirectional pulse waveform is used without adding a resting interval; therefore, the pulse current amplitude ratio is set to 1:1, and there is no pulse interval;

[0079] The positive and negative pulses of the bidirectional pulse waveform have a constant root mean square value of the current within one cycle;

[0080] The pulse current is a heating pulse current determined based on a pre-obtained optimal heating pulse period and a heating maximum pulse charging amplitude.

[0081] The fast charging strategy includes:

[0082] Determine the fast charge current based on the fast charge optimal pulse period and the fast charge maximum pulse charging amplitude obtained in advance;

[0083] The fast charging current is adjusted by using a PID control method to determine an initial charging current value;

[0084] Determining the charging current according to the initial charging current value and preset constraints;

[0085] The battery is pulse charged based on the charging current.

[0086] It should be noted that in the fast charging stage, the PID method is used to calculate the current adjustment value, that is, the initial charging current value, which is added to the current control cycle to keep the negative electrode overpotential positive to prevent lithium precipitation. The adjustment value of PID control is:

[0087]

[0088] In the formula, u T is the initial charging current value at time T, K p is the first linear parameter, e T is the error between the negative electrode overpotential at time T and the lithium precipitation threshold, K i is the second linear parameter, e T is the error between the negative electrode overpotential at time T and the lithium precipitation threshold, K d is the third linear parameter, e T-1 is the error between the negative electrode overpotential at time T-1 and the lithium deposition threshold.

[0089] Furthermore, the preset constraints include: charging current constraint and total power constraint;

[0090] The charging current constraint includes: the charging current of the battery is less than the maximum charging current multiple;

[0091] The total power constraint includes: the total charging power of the battery is less than or equal to the maximum total charging power.

[0092] It should be noted that, in the pulse heating stage, the process of determining the optimal heating pulse period and the maximum heating pulse charging amplitude obtained in advance includes:

[0093] 1. The cycle of battery pulses is mainly concentrated in the time scale of seconds and 1-2 minutes. Longer duration will increase the risk of lithium dendrites and other side reactions, accelerating battery degradation. According to the above rules, a series of charging experiments with different pulse cycles are designed, while keeping other parameters unchanged, observing the charging efficiency of the battery under different cycles, and selecting the pulse cycle with the best charging efficiency as the optimal heating pulse cycle.

[0094] 2. Under fixed temperature conditions, perform charging tests on the battery at different SOCs (such as 10%, 20%, ..., 90%, 100%), select the maximum allowable charging current to pulse charge the battery until the predetermined SOC value or the battery voltage upper limit is reached, repeat the above charging process for each SOC point, and record the changes in voltage, current and time required during the charging process.

[0095] 3. Set the pulse current period to the optimal period in 1 (set to 1s in this example), and use the given amplitude, SOC, and temperature data as coordinate axes to generate a three-dimensional graph. Process the test data in 2 through interpolation method, and draw a MAP diagram of pulse heating to determine the maximum pulse charging amplitude under different SOCs and temperatures, that is, the maximum heating pulse charging amplitude.

[0096] The charging current is adjusted using the current regulation value calculated by PID control. If the error is positive (i.e. the actual overpotential is lower than the target overpotential), the current is increased; if the error is negative (i.e. the actual overpotential is higher than the target overpotential), the current is reduced. The purpose is to keep the negative electrode overpotential positive to prevent lithium deposition.

[0097] For example, in the pulse heating stage, the waveform period of the pulse current can be set to 1s, the amplitude increases by 0.001C per period, the SOC ranges from 0.1 to 0.9 with an interval of 0.01, and the temperature ranges from -20°C to 40°C with an interval of 2.5°C.

[0098] The optimal temperature switching threshold Tt is calculated using the entropy weight method. When the battery performs pulse heating operation until the temperature rises to Tt, it performs fast charging operation instead. The optimal temperature switching threshold Tt is the heating temperature switching threshold, and different heating temperature switching thresholds correspond to different charging currents and SOCs.

[0099] In order to balance the energy cost of the heating process and the charging rate, the energy efficiency η of the battery charging process is calculated:

[0100]

[0101] Where ΔE is the stored energy in the battery associated with the initial and final SOC, and u and i are the voltage and current during the charging process, respectively.

[0102] In order to make the charging time shorter and more efficient, a linear target weighting function is used to determine the switching thresholds of each heating temperature and its corresponding heating time:

[0103] From the initial temperature T0, set n temperature switching thresholds, namely the heating temperature switching thresholds, and the time of the heating process is t. First, standardize the charging time and energy efficiency:

[0104]

[0105] In the formula, is the normalized value of the time required to heat to the i-th temperature switching threshold, t max is the maximum heating time, t i is the time to heat to the i-th temperature switching threshold, t min is the minimum heating time, is the normalized value of the energy efficiency of heating to the i-th temperature switching threshold, η i is the energy efficiency of heating to the i-th temperature switching threshold, η max is the maximum energy efficiency, η min is the minimum value of energy efficiency;

[0106] Calculate the ratio of the normalized value of the time required to heat to the i-th temperature switching threshold and the normalized value of the energy efficiency required to heat to the i-th temperature switching threshold:

[0107]

[0108] In the formula, p t,i is the ratio of the normalized value of the time to the i-th temperature switching threshold, p η,i is the ratio of the normalized values ​​of the energy efficiency for heating to the i-th temperature switching threshold;

[0109] Calculate the information entropy E corresponding to the ratio of the normalized value of the time required to heat to the i-th temperature switching threshold t,i The information entropy E corresponding to the ratio of the normalized value of the energy efficiency of heating to the i-th temperature switching threshold η,i :

[0110]

[0111] The information entropy E corresponding to the ratio of the normalized value of the time to the i-th temperature switching threshold t,i The information entropy E corresponding to the ratio of the normalized value of the energy efficiency of heating to the i-th temperature switching threshold η,i Determine the weight k corresponding to the time normalized value of heating to the i-th temperature switching threshold t,i , the weight k corresponding to the normalized value of the energy efficiency of heating to the i-th temperature switching threshold η,i:

[0112]

[0113] Solving the objective function The i-th optimal temperature switching threshold and heating time are obtained, that is, the temperature switching threshold Tt and heating time t corresponding to the maximum objective function value f are selected, so that a higher charging efficiency can be obtained in a shorter time.

[0114] It should be noted that the process of determining the pre-obtained optimal fast charging pulse period and the maximum pulse charging amplitude of fast charging in the fast charging stage is the same as the method of determining the optimal pulse period in the pulse heating stage, recording the changes in voltage, current and time required during the charging process, and determining the maximum pulse charging amplitude under different SOCs and temperatures.

[0115] For example, the current in the fast charging stage is adjusted every 1-5s, with a cycle of 20s. The SOC range is from 0.1 to 0.9, with an interval of 0.01, and the temperature range is from -10℃ to 40℃, with an interval of 2.5℃. The amplitude of the pulse current increases by 0.001C every 10 seconds. When the negative electrode overpotential reaches 0V, the current amplitude is regarded as the maximum charging current in this state.

[0116] In an embodiment of the present disclosure, the method further includes:

[0117] When charging is performed based on a preset fast charging strategy, if the temperature of the battery is less than or equal to a preset heating temperature switching threshold, the preset pulse heating strategy is used to heat the temperature of the battery to the preset heating temperature switching threshold, and then the vehicle's battery is pulse charged based on the energy allocation strategy and the preset fast charging strategy.

[0118] Specifically, when it is determined that the battery is at or below the low temperature threshold T0, a square wave pulse current is applied to heat the battery to the heating temperature switching threshold. When the temperature reaches the heating temperature switching threshold Tt1, the pulse heating mode is switched to the fast charging mode. During the fast charging process, the temperature will gradually decrease due to environmental influences. When it drops to Tt2, the second heating to the temperature Tt3 is started, and the battery is switched to the fast charging mode until the SOC reaches the cutoff value.

[0119] In an embodiment of the present disclosure, the method further includes:

[0120] measuring the negative electrode overpotential of the battery in real time;

[0121] In the low-temperature heating stage, if the negative electrode overpotential is greater than the first lithium deposition threshold value of -0.05V, lithium deposition is determined and charging is stopped;

[0122] In the fast charging stage, if the negative electrode overpotential is greater than the second lithium deposition threshold value 0V, lithium deposition is determined and charging is stopped.

[0123] In an embodiment of the present disclosure, the method further includes:

[0124] The economy, durability and consistency of the battery charging process were evaluated.

[0125] It should be noted that the economic efficiency is the bill for the entire charging process, including: the income from the electricity generated by the new energy power generation equipment, the income from the charging piles and the cost of the energy conversion equipment.

[0126] The durability is the battery health state SOH, which is calculated as follows:

[0127]

[0128] In the formula, C dis_actual is the actual discharge capacity, C dis_initial is the initial discharge capacity, where SOC(N) represents the SOC value at the end of the charging segment, SOC(0) represents the SOC value at the beginning of the charging segment, I(k) is the current value at the k+1th sampling point, and ΔT(k) is the sampling interval.

[0129] The consistency includes: voltage consistency, temperature consistency and SOC consistency;

[0130] The voltage consistency is evaluated by calculating the root mean square error and coefficient of variation of the collected single cell voltage:

[0131]

[0132]

[0133] Among them, V i,j V represents the voltage value of the ith single cell (n single cells in total) at time j (k moments in total), n,j It represents the average voltage of each monomer voltage at the jth moment in the charging stage, and V represents the average value of the average voltage.

[0134] The root mean square error is:

[0135]

[0136] RSME V Indicates the discrete degree between the voltages of each single cell in the k time period, that is, RSME V The smaller the voltage, the better the voltage consistency; V It can reflect the utilization rate of the battery pack during actual use, δ V The smaller it is, the better the voltage consistency.

[0137] Temperature consistency: The calculation method is the same as above, and the same calculation is performed on the temperature data T of n temperature sensors within the k time period.

[0138] SOC consistency:

[0139]

[0140] Among them, SOC i represents the SOC of the i-th single cell, Indicates the average value of SOC of each single battery. max is the maximum single cell SOC, SOC min is the minimum single cell SOC. p+ Represents the maximum positive dispersion of battery SOC, σ p- Indicates the maximum negative dispersion of the battery SOC. The smaller the positive / negative dispersion, the better the SOC consistency.

[0141] It should be noted that the method further includes:

[0142] When the electricity price is at the peak price or there are other behaviors related to the electricity market such as demand-side response, the battery of the electric vehicle can be controlled to discharge to maximize the benefits.

[0143] In summary, the vehicle-grid interactive charging method based on the microgrid simulation platform proposed in this embodiment solves the demand for rapid charging of electric vehicles in low temperature environments in applications, while ensuring the life of the battery.

[0144] Based on the above vehicle-grid interactive charging method, this embodiment also provides a structural diagram of a vehicle-grid interactive pulse charging system based on a microgrid simulation platform, such as Figure 2 As shown, the system comprises:

[0145] The acquisition module 100 is used to obtain the current battery capacity, required battery capacity, vehicle pick-up time, and peak and valley electricity price periods of the vehicle;

[0146] A first determination module 200 is used to determine a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time, and the peak-valley electricity price period;

[0147] The second determination module 300 is used to obtain the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determine the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period;

[0148] The charging control module 400 is used to monitor the temperature of the battery in real time during the peak-valley charging period, and determine whether to start the pulse heating strategy based on the temperature. If started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy. Otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

[0149] In the embodiment of the present disclosure, the first determining module 200 is further configured to:

[0150] Determining the time required to charge the battery according to the current battery capacity, the required battery capacity, and the vehicle pickup time;

[0151] It is determined whether the battery can be charged during the valley price period according to the peak-valley electricity price period and the time required for charging. If so, charging is performed during the valley price period; otherwise, charging is started immediately.

[0152] Furthermore, the second determining module 300 is further configured to:

[0153] Determine the charging power and voltage of the battery at each moment according to the current battery capacity, the required battery capacity and the peak and valley charging time period;

[0154] Determine whether the voltage and power of the new energy power generation equipment at each moment correspond to the charging power and voltage of the battery at each moment. If so, use the voltage and power of the new energy power generation equipment at each moment as the energy allocation strategy. Otherwise, determine the difference between the voltage and power of the new energy power generation equipment at each moment and the charging power and voltage of the battery at each moment, and determine the energy allocation strategy based on the difference corresponding to each moment.

[0155] Furthermore, the charging control module 400 is also used for:

[0156] It is determined whether the temperature of the battery is less than a low temperature threshold, and if so, the pulse heating strategy is started; otherwise, the pulse heating strategy is not started.

[0157] It should be noted that the pulse heating strategy includes:

[0158] Using a pulse current to heat the battery to a preset heating temperature switching threshold within a preset heating time;

[0159] Wherein, the preset heating time and the preset heating temperature switching threshold are determined by using a linear target weighting function;

[0160] The waveform of the pulse current is a bidirectional pulse waveform;

[0161] The bidirectional pulse waveform satisfies the formula I P ×T P =-I N ×T N , where I P is the positive pulse amplitude, T P is the duration of the positive pulse, I N is the reverse pulse amplitude, T N is the reverse pulse duration;

[0162] The positive and negative pulses of the bidirectional pulse waveform have a constant root mean square value of the current within one cycle;

[0163] The pulse current is a heating pulse current determined based on a pre-obtained optimal heating pulse period and a heating maximum pulse charging amplitude;

[0164] The fast charging strategy includes:

[0165] Determine the fast charge current based on the fast charge optimal pulse period and the fast charge maximum pulse charging amplitude obtained in advance;

[0166] The fast charging current is adjusted by using a PID control method to determine an initial charging current value;

[0167] Determining the charging current according to the initial charging current value and preset constraints;

[0168] pulse charging the battery based on the charging current;

[0169] Wherein, the preset constraint conditions include: charging current constraint and total power constraint;

[0170] The charging current constraint includes: the charging current of the battery is less than the maximum charging current multiple;

[0171] The total power constraint includes: the total charging power of the battery is less than or equal to the maximum total charging power.

[0172] In the embodiments of the present disclosure, Figure 3 As shown, the system further includes: a monitoring control module 500 for:

[0173] When charging is performed based on a preset fast charging strategy, if the temperature of the battery is less than or equal to a preset heating temperature switching threshold, the preset pulse heating strategy is used to heat the temperature of the battery to the preset heating temperature switching threshold, and then the vehicle's battery is pulse charged based on the energy allocation strategy and the preset fast charging strategy.

[0174] In the embodiments of the present disclosure, Figure 4As shown, the system further includes: an evaluation module 600 for:

[0175] The economy, durability and consistency of the battery charging process were evaluated.

[0176] It should be noted that the structure of the vehicle-grid interactive charging system based on the microgrid simulation platform provided in this embodiment can also be as follows: Figure 5 As shown, it includes: an electric vehicle power battery 1, a V2G charging pile 2, an MGCC communication module 3, a first energy storage device 4, a power distribution cabinet 5, a power conversion system (PCS. Power Convers ion System) 6, a DCDC 7, a new energy power generation module 8, a router 9, and a microgrid simulation platform 10, wherein the microgrid simulation platform 10 includes: a cluster module 10-1, a strategy module 10-2, and the MGCC communication module 3 includes: an RS485 gateway 3-1, a CAN gateway 3-2 and an MGCC module 3-3, and the RS485 gateway 3-1, the CAN gateway 3-2 and the MGCC module 3-3 are all used to support communication;

[0177] It should be noted that the V2G charging pile 2, the first energy storage device 4, the PCS 6, the new energy generation module 8 and the router 9 are all configured with electric meters for collecting voltage information of the corresponding devices, wherein the voltage information shown belongs to operation information;

[0178] Among them, the number of the V2G charging piles 2, the first energy storage device 4 and the new energy power generation module 8 can be multiple, multiple V2G charging piles 2 correspond to one electric meter, multiple energy storage devices 4 correspond to one electric meter, and multiple new energy power generation modules 8 correspond to one electric meter.

[0179] The V2G charging pile 2 is a pulse charging pile, which may be provided with a second energy storage device;

[0180] When a second energy storage device is provided in the V2G charging pile 2, the second energy storage device is used to perform low-frequency charging and discharging and medium- and high-frequency pulse operations;

[0181] When the second energy storage device is not provided in the V2G charging pile 2, the same function can be achieved through the AC / DC bus and the first energy storage device 4 connected to the microgrid.

[0182] Furthermore, the second energy storage device and the first energy storage device 4 provided in the V2G charging pile 2 may be supercapacitors.

[0183] The new energy power generation module 8 includes wind power generation equipment and photovoltaic power generation equipment. Since its output voltage and power are volatile and uncertain, it is connected to the DCDC converter, namely DCDC7, to adjust the voltage and power to meet the needs of the microgrid. At the same time, the electric vehicle power battery 1 is also connected to DCDC7 to convert the output voltage of the energy storage battery into a voltage level suitable for the load equipment. At the same time, it can also adjust the bidirectional flow of electric energy according to the needs of the power grid to achieve the charge and discharge management of the energy storage system.

[0184] During the charging process, the operation information of the electric vehicle power battery 1, the V2G charging pile 2, the first energy storage device 4, the distribution cabinet 5, the PCS6, the DCDC7, and the new energy power generation module 8 is collected, and the operation information is sent to the cluster module 10-1 of the microgrid simulation platform 10 through the MGCC communication module 3 and the router 9. The cluster module 10-1 aggregates the same type of devices into an independent cluster for management, so that the same type of devices are treated as a whole. When formulating strategies, there is no need to consider the device composition and device status of the microgrid, and then the operation information is sent to the strategy module 10-2. The strategy module 10-2 generates an energy distribution strategy, a pulse heating strategy and a fast charging strategy based on the operation information, and then sends the energy distribution strategy, the pulse heating strategy and the fast charging strategy to the cluster module 10-1. The cluster module 10-1 sends the energy distribution strategy, the pulse heating strategy and the fast charging strategy to the corresponding devices through the MGCC communication module 3 and the router 9 to control the charging of the battery.

[0185] In summary, the vehicle-grid interactive pulse charging system based on the microgrid simulation platform proposed in this embodiment solves the demand for rapid charging of electric vehicles in low temperature environments, while ensuring the life of the battery.

[0186] Embodiment 2

[0187] In order to implement the above embodiments, the present disclosure further proposes an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in Embodiment 1 is implemented.

[0188] Embodiment 3

[0189] In order to implement the above embodiments, the present disclosure further proposes a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method described in the first embodiment is implemented.

[0190] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0191] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0192] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A vehicle-grid interactive pulse charging method based on a microgrid simulation platform, characterized in that: The method comprises: Obtain the vehicle's current battery capacity, required battery capacity, vehicle pickup time, and peak and valley electricity price periods; Determine a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time, and the peak-valley electricity price period; Obtaining the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determining the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period; During the peak-valley charging period, the temperature of the battery is monitored in real time, and it is determined whether to start the pulse heating strategy based on the temperature. If started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy. Otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

2. The method according to claim 1, characterized in that Determining the peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pickup time and the peak-valley electricity price period includes: Determining the time required to charge the battery according to the current battery capacity, the required battery capacity, and the vehicle pickup time; It is determined whether the battery can be charged during the valley price period according to the peak-valley electricity price period and the time required for charging. If so, charging is performed during the valley price period; otherwise, charging is started immediately.

3. The method according to claim 2, characterized in that The energy allocation strategy is determined according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak and valley charging period, including: Determine the charging power and voltage of the battery at each moment according to the current battery capacity, the required battery capacity and the peak and valley charging time period; Determine whether the voltage and power of the new energy power generation equipment at each moment correspond to the charging power and voltage of the battery at each moment. If so, use the voltage and power of the new energy power generation equipment at each moment as the energy allocation strategy. Otherwise, determine the difference between the voltage and power of the new energy power generation equipment at each moment and the charging power and voltage of the battery at each moment, and determine the energy allocation strategy based on the difference corresponding to each moment.

4. The method according to claim 3, characterized in that The method of monitoring the temperature of the battery in real time during the peak-valley charging period and determining whether to start the pulse heating strategy according to the temperature includes: It is determined whether the temperature of the battery is less than a low temperature threshold, and if so, the pulse heating strategy is started; otherwise, the pulse heating strategy is not started.

5. The method according to claim 4, characterized in that The pulse heating strategy includes: Using a pulse current to heat the battery to a preset heating temperature switching threshold within a preset heating time; Wherein, the preset heating time and the preset heating temperature switching threshold are determined by using a linear target weighting function; The waveform of the pulse current is a bidirectional pulse waveform; The bidirectional pulse waveform satisfies the formula I P ×T P =-I N ×T N , where I P is the positive pulse amplitude, T P is the duration of the positive pulse, I N is the reverse pulse amplitude, T N is the reverse pulse duration; The positive and negative pulses of the bidirectional pulse waveform have a constant root mean square value of the current within one cycle; The pulse current is a heating pulse current determined based on a pre-obtained optimal heating pulse period and a heating maximum pulse charging amplitude; The fast charging strategy includes: Determine the fast charge current based on the fast charge optimal pulse period and the fast charge maximum pulse charging amplitude obtained in advance; The fast charging current is adjusted by using a PID control method to determine an initial charging current value; Determining the charging current according to the initial charging current value and preset constraints; pulse charging the battery based on the charging current; Wherein, the preset constraint conditions include: charging current constraint and total power constraint; The charging current constraint includes: the charging current of the battery is less than the maximum charging current multiple; The total power constraint includes: the total charging power of the battery is less than or equal to the maximum total charging power.

6. The method according to claim 5, characterized in that The method further comprises: When charging is performed based on a preset fast charging strategy, if the temperature of the battery is less than or equal to a preset heating temperature switching threshold, the preset pulse heating strategy is used to heat the temperature of the battery to the preset heating temperature switching threshold, and then the vehicle's battery is pulse charged based on the energy allocation strategy and the preset fast charging strategy.

7. The method according to claim 1, characterized in that The method further comprises: The economy, durability and consistency of the battery charging process were evaluated.

8. A vehicle-grid interactive pulse charging system based on a microgrid simulation platform, characterized in that: The system comprises: The acquisition module is used to obtain the vehicle's current battery capacity, required battery capacity, vehicle pickup time, and peak and valley electricity price periods; A first determination module is used to determine a peak-valley charging period according to the current battery capacity, the required battery capacity, the vehicle pick-up time and the peak-valley electricity price period; The second determination module is used to obtain the voltage and power of the new energy power generation equipment at each moment in the peak-valley charging period, and determine the energy allocation strategy according to the voltage and power of the new energy power generation equipment at each moment, the current battery capacity, the required battery capacity and the peak-valley charging period; The charging control module is used to monitor the temperature of the battery in real time during the peak-valley charging period, and determine whether to start the pulse heating strategy based on the temperature; if started, the temperature of the battery is heated to a preset heating temperature switching threshold based on the pulse heating strategy, and then the battery of the vehicle is pulse charged based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy; otherwise, the battery of the vehicle is pulse charged directly based on the peak-valley charging period, the energy allocation strategy and the preset fast charging strategy.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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