CN115520041A

CN115520041A - Mobile charging vehicle capable of detecting health degree of battery and implementation method thereof

Info

Publication number: CN115520041A
Application number: CN202211343540.0A
Authority: CN
Inventors: 于远彬; 黄腾飞; 李东光; 冯鸣跃; 刘镇宁; 张晓龙; 蒋俊宇
Original assignee: Beijing Hua Ao Automobile Service Co ltd; Jilin University
Current assignee: Beijing Hua Ao Automobile Service Co ltd; Jilin University
Priority date: 2022-10-31
Filing date: 2022-10-31
Publication date: 2022-12-27

Abstract

The invention discloses a mobile charging vehicle capable of detecting the health degree of a battery and an implementation method thereof. The system can charge the charging car by using various charging piles, can meet the power supplementing requirements of various electric cars through alternating current slow charging and direct current fast charging, and can realize the fast detection of the health degree of the battery of the charged car; the voltage boosting and reducing operations of the mobile charging vehicle can be completed by only using one bidirectional DCDC power supply conversion module, so that the charging of the high-voltage battery pack and the discharging of the charged vehicle are completed; the on-line detection of the health degree of the vehicle-mounted battery of the new energy automobile can be realized only through the information of the battery of the charged vehicle and the information of the charging process, and a long-term battery life cycle test and a full charge and discharge test are not required; the multi-time scale extended Kalman filtering algorithm and the recursive least square method are combined, so that the battery parameter identification and battery health degree detection precision is effectively improved; meanwhile, the detection stopping condition is set, so that the reliability and stability of the battery health degree result are ensured.

Description

Mobile charging vehicle capable of detecting health degree of battery and implementation method thereof

Technical Field

The invention relates to a battery detection technology of an electric vehicle, in particular to a mobile charging vehicle capable of detecting the health degree of a battery and an implementation method thereof.

Background

In order to protect the environment and save energy, lithium ion batteries are widely used in the field of electric vehicles, but the endurance mileage of electric vehicles is limited, and the imperfect layout of charging piles is a key factor that restricts further development of electric vehicles. Under the condition that no charging pile is arranged nearby, the mobile charging vehicle can be used as an emergency charging device to timely supplement power for various electric automobiles.

The method for accurately evaluating the health degree of the vehicle-mounted battery of the electric vehicle is beneficial to timely mastering the health state of the battery and is also beneficial to the development of insurance business of the electric vehicle and the echelon recycling of the battery. However, most of the existing battery health degree detection equipment are special equipment, the battery health degree detection equipment is inconvenient to move and single in function, a large number of battery aging tests and vehicle full charge and discharge tests are required before testing, time and labor are consumed, and meanwhile, the health degree on-line estimation also faces the problem that data saturation and precision are difficult to guarantee.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides the mobile charging vehicle capable of detecting the battery health degree and the implementation method thereof, which have the function of rapidly supplying power to the electric vehicle without a direct-current rapid charging pile and can detect the battery health degree of the charged vehicle.

One objective of the present invention is to provide a mobile charging cart capable of detecting the health degree of a battery.

The invention discloses a mobile charging vehicle capable of detecting the health degree of a battery, which comprises: the system comprises a high-voltage battery pack, a first distribution box, a second distribution box, a bidirectional Direct Current to Direct Current (DCDC) power conversion module, a Direct Current to Alternating Current (DCAC) power conversion module, an Alternating Current charger, an Alternating Current output socket, an Alternating Current charging socket, a first Direct Current charging socket, a second Direct Current charging socket, an air switch, a low-voltage power supply module, a charging start button, an emergency stop button, a Direct Current charging gun, a thermal management system, a vehicle control module, a touch liquid crystal screen and a data recording module; the high-voltage battery pack is respectively connected to the bidirectional DCDC power conversion module, the alternating current charger, the first direct current charging socket, the DCAC power conversion module and the low-voltage power supply module through the first distribution box; the bidirectional DCDC power conversion module is respectively connected to the direct-current charging gun, the second direct-current charging socket and the thermal management system through a second distribution box; the alternating current charger is connected to the alternating current output socket; the DCAC power conversion module is connected to the AC output socket; the low-voltage power supply module is respectively connected to the vehicle control module, the touch liquid crystal screen, the data recording module and the thermal management system;

the vehicle control module comprises a first direct current charging socket control panel, a second direct current charging socket control panel, a direct current charging gun control panel and a vehicle control unit, communication modules arranged in the first direct current charging socket control panel, the second direct current charging socket control panel and the direct current charging gun control panel are respectively connected with communication lines of the first direct current charging socket, the second direct current charging socket and the direct current charging gun, the first direct current charging socket control panel, the direct current charging gun control panel, the vehicle control unit, a high-voltage battery pack, a DCAC power conversion module, a bidirectional DCDC power conversion module, an alternating current charger, a data recording module, a touch-control liquid crystal screen and a compressor and a PTC heater in a heat management system are respectively provided with respective communication modules, and have communication functions, and all the communication modules are mutually connected to form a vehicle communication network of the mobile charging vehicle;

the first distribution box comprises a first distribution box shell, a high-voltage battery pack interface, a bidirectional DCDC power conversion module interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface, a low-voltage power supply module interface, a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay; the first distribution box is hollow, a high-voltage battery pack interface, a bidirectional DCDC power conversion module input interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface and a low-voltage power supply module interface are respectively arranged on the surface of the first distribution box, and a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay are arranged in the first distribution box; the output end of the high-voltage battery pack is connected to a high-voltage battery pack interface, the high-voltage battery pack interface is connected to an input interface of the bidirectional DCDC power conversion module through a battery high-voltage relay, the high-voltage battery pack interface is connected to an alternating current charger interface through the battery high-voltage relay and a first high-voltage relay, the high-voltage battery pack interface is connected to a first direct current charging socket interface through the battery high-voltage relay and a second high-voltage relay, and the high-voltage battery pack interface is also connected to a DCAC power conversion module interface and a low-voltage power supply module interface respectively; the input interface of the bidirectional DCDC power conversion module is connected to the input end of the bidirectional DCDC power conversion module; the interface of the alternating current charger is connected to the alternating current charger; the first direct current charging socket interface is connected to the first direct current charging socket; the DCAC power conversion module interface is connected to the DCAC power conversion module; the low-voltage power supply module interface is connected to the low-voltage power supply module through an air switch; the vehicle control unit is respectively connected with the battery high-voltage relay, the first high-voltage relay and the second high-voltage relay through control lines and is used for controlling the on-off of each high-voltage relay;

the second distribution box comprises a second distribution box shell, a bidirectional DCDC power conversion module output interface, a second direct current charging socket interface, a thermal management system interface, a direct current charging gun interface, a third high-voltage relay and a fourth high-voltage relay; the second distribution box shell is hollow, the surface of the second distribution box shell is respectively provided with a bidirectional DCDC power conversion module output interface, a second direct-current charging socket interface, a thermal management system interface and a direct-current charging gun interface, and a third high-voltage relay and a fourth high-voltage relay are arranged in the second distribution box shell; the output end of the bidirectional DCDC power supply conversion module is connected to the output interface of the bidirectional DCDC power supply conversion module; the output interface of the DCDC power conversion module is connected to the second direct-current charging socket interface; the output interface of the DCDC power supply conversion module is connected to the interface of the direct current charging gun through a third high-voltage relay; the output interface of the DCDC power supply conversion module is connected to the interface of the thermal management system through a fourth high-voltage relay; the second direct current charging socket interface is connected to a second direct current charging socket; the direct current charging gun interface is connected to the direct current charging gun through a charging start button and an emergency stop button; the thermal management system interface is connected to a compressor and a thermistor (PTC) heater in the thermal management system; the vehicle control unit is respectively connected with the third high-voltage relay and the fourth high-voltage relay through control lines and is used for switching on and off of each high-voltage control relay;

the charging and discharging modes of the mobile charging vehicle comprise: the method comprises a first direct current charging mode, a second direct current charging mode, an alternating current slow charging mode, a quick power supplementing mode, a health degree detection mode and an alternating current output mode:

in a first direct current charging mode, a first direct current charging socket is connected to a direct current charging pile, the vehicle control unit controls the battery high-voltage relay and the second high-voltage relay to be closed, and other high-voltage relays are opened to charge the high-voltage battery pack; in the charging process, the first direct current charging socket control board acquires real-time voltage, state of Charge (SOC) and maximum charging current information of the high-voltage battery pack from a whole vehicle communication Network in real time, and completes Controller Area Network (CAN) communication between the mobile charging vehicle and the charging pile;

in a second direct-current charging mode, a second direct-current charging socket is connected to a direct-current charging pile with the highest voltage exceeding the highest voltage of the high-voltage battery pack, the vehicle control unit controls the battery high-voltage relay and the fourth high-voltage relay to be closed, and other high-voltage relays are disconnected to charge the high-voltage battery pack; in the charging process, the second direct-current charging socket control board acquires the real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from a finished automobile communication network, the maximum charging current of the second direct-current charging mode is the smaller value of the maximum charging current of the high-voltage battery pack and the maximum allowable current of the bidirectional DCDC power conversion module, meanwhile, the voltage of the output end of the bidirectional DCDC power conversion module is controlled to be lower than the highest voltage of the direct-current charging pile and is kept constant, and then the voltage is boosted through the bidirectional DCDC power conversion module;

under an alternating-current slow charging mode, an alternating-current charging socket is connected to an alternating-current charging pile, the vehicle control unit controls the battery high-voltage relay and the first high-voltage relay to be closed, and other high-voltage relays are disconnected to charge the high-voltage battery pack; in the charging process, the vehicle control unit is responsible for completing the confirmation of the slow charging process and outputting the allowed slow charging current; the alternating current charger obtains the allowed slow charging current at the moment from the communication network of the whole vehicle, and adjusts the voltage at the output end of the alternating current charger;

under the rapid power supply mode, the direct-current charging gun is connected to a battery of a charged vehicle, the rapid power supply mode is selected from the touch liquid crystal screen, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the high-voltage battery pack rapidly charges the charged vehicle; in the charging process, the direct-current charging gun control panel completes CAN communication between the mobile charging vehicle and the vehicle to be charged, obtains the maximum discharging current of the high-voltage battery pack from the whole vehicle communication network, adjusts the voltage of the outlet end of the bidirectional DCDC power supply conversion module so as to control the output current, and at the moment, the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the vehicle to be charged, so that the rapid direct-current charging of the vehicle to be charged is realized;

under the health degree detection mode, the direct-current charging gun is connected to a battery of a charged vehicle, the health degree detection mode is selected in the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the battery health degree of the charged vehicle is detected by using the mobile charging vehicle; in the charging process, the vehicle control unit adjusts the maximum discharging current of the high-voltage battery pack in real time, the current range is 0 to the smaller value of the required current of the charged vehicle and the maximum discharging current of the high-voltage battery pack, so that the maximum output current of the outlet end of the DCDC power supply conversion module is limited, the charged vehicle is charged according to a specific pulse current form, and the health degree of the charged vehicle is detected according to the voltage response of the charged vehicle;

under a first direct current charging mode, a second direct current charging mode, an alternating current slow charging mode, a quick power supplementing mode and a health degree detection mode, the battery high-voltage relay protects the high-voltage battery pack from overcurrent damage in the charging and discharging process;

under the alternating current output mode, the alternating current output socket is connected to an electric appliance needing power supply;

the whole vehicle controller controls the opening and closing of the first high-voltage relay, the second high-voltage relay, the third high-voltage relay and the fourth high-voltage relay, and at most one high-voltage relay in the four high-voltage relays is closed at the same time, so that the unicity of the charging and discharging mode of the mobile charging vehicle is guaranteed.

The thermal management system comprises: the system comprises a compressor, an outdoor heat exchanger, a thermal expansion valve, a plate heat exchanger, a PTC heater, a first temperature sensor, a second temperature sensor, a water pump and a three-way valve; the mobile charging vehicle adopts an integrated heat management loop and comprises a cooling liquid loop and a refrigerant loop: in the cooling liquid loop, one side of the high-voltage battery pack is connected to the PTC heater through a water pipe, a first temperature sensor is arranged on the water pipe connecting the high-voltage battery pack to the PTC heater, and the PTC heater is connected to a first outlet of the three-way valve; one side of the bidirectional DCDC power supply conversion module is connected to a second outlet of the three-way valve through a pipeline, a second temperature sensor is arranged on the pipeline connecting the bidirectional DCDC power supply conversion module to the second outlet of the three-way valve, the other side of the high-voltage battery pack and the other side of the bidirectional DCDC power supply conversion module are connected with one side of a water pump, the other side of the water pump is connected with a first interface of the plate heat exchanger, and a second interface of the plate heat exchanger is connected with an inlet of the three-way valve; in the refrigerant loop, the outlet of the compressor, the outdoor heat exchanger and the inlet of the thermostatic expansion valve are sequentially connected, the outlet of the thermostatic expansion valve is connected with the third interface of the plate heat exchanger, and the fourth interface of the plate heat exchanger is connected with the inlet of the compressor. The first temperature sensor, the second temperature sensor, the three-way valve and the water pump are respectively connected with a vehicle controller of a vehicle control module through control lines; the thermal management system is used for keeping the high-voltage battery pack and the bidirectional DCDC power conversion module in a proper working temperature range.

The data recording module is connected to an upper computer through a communication module; acquiring charging information of a charged vehicle from a vehicle communication network, wherein the charging information comprises battery type, SOC (system on chip), battery voltage, battery current, battery temperature and maximum voltage information of a battery monomer; and the system is stored in an upper computer and used for recording the battery health degree of the charged vehicle and constructing a new energy automobile charging database.

The touch liquid crystal screen is used for displaying information of the high-voltage battery pack, the bidirectional DCDC power supply conversion module and the vehicle control module; meanwhile, the touch liquid crystal display can be used for setting thresholds of overvoltage early warning, undervoltage early warning and overtemperature early warning of the bidirectional DCDC power supply conversion module; when the direct current charging gun is connected with a charged vehicle, the touch liquid crystal screen is also used for displaying charging information of the charged vehicle and selecting a quick power supply mode or a health degree detection mode.

The vehicle control module includes: the system comprises a vehicle control unit, a first direct current charging socket control panel, a second direct current charging socket control panel and a direct current charging gun control panel; the vehicle control unit is used for estimating the state of the high-voltage battery pack, judging the charging and discharging mode of the mobile charging vehicle and performing thermal management control; the vehicle controller firstly estimates the State of Charge (SOC) and the Power State (SOP) of the high-voltage battery pack according to battery monomer information acquired from a vehicle communication network, prevents the battery from being overcharged and overdischarged, and uploads the battery pack State to the vehicle communication network; secondly, the vehicle control unit judges the charging and discharging mode of the mobile charging vehicle according to the connection condition of the alternating current charging socket, the first direct current charging socket, the second direct current charging socket and the direct current charging gun at the moment, adjusts the maximum charging and discharging current of the high-voltage battery pack and controls the opening and closing of a high-voltage relay of the battery; and finally, judging a thermal management mode of the mobile charging vehicle according to the temperatures of the high-voltage battery pack and the bidirectional DCDC power conversion module, and controlling the working state of the thermal management system component, wherein the thermal management mode of the mobile charging vehicle comprises a single-cold mode of the high-voltage battery pack, a single-cold mode of the bidirectional DCDC power conversion module, a double-cold mode of the high-voltage battery pack and the bidirectional DCDC power conversion module, and a single-hot mode of the high-voltage battery pack.

The first direct current charging socket control panel is used for being matched with the first direct current charging socket to realize a first direct current charging mode in a charging and discharging mode of the mobile charging vehicle; the second direct-current charging socket control board is used for being matched with the second direct-current charging socket to realize a second direct-current charging mode in the charging and discharging module of the mobile charging vehicle; the direct-current charging gun control panel is used for being matched with the direct-current charging gun to realize a quick charging mode and a health degree detection mode in the charging and discharging mode of the mobile charging vehicle.

The invention also aims to provide a realization method of the mobile charging vehicle capable of detecting the health degree of the battery.

The invention discloses a method for realizing a mobile charging vehicle capable of detecting the health degree of a battery, which comprises the following steps:

a) In a first direct current charging mode, a first direct current charging socket is connected to a direct current charging pile, the vehicle control unit controls the battery high-voltage relay and the second high-voltage relay to be closed, and other high-voltage relays are opened to charge the high-voltage battery pack; in the charging process, the first direct-current charging socket control board acquires real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from a whole vehicle communication Network, and completes Controller Area Network (CAN) communication between the mobile charging vehicle and the charging pile;

b) In a second direct-current charging mode, a second direct-current charging socket is connected to a direct-current charging pile with the highest voltage exceeding the highest voltage of the high-voltage battery pack, the vehicle controller controls the battery high-voltage relay and the fourth high-voltage relay to be closed, the high-voltage battery pack is charged, and other high-voltage relays are disconnected; in the charging process, the second direct-current charging socket control board acquires the real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from a finished automobile communication network, the maximum charging current of the second direct-current charging mode is the smaller value of the maximum charging current of the high-voltage battery pack and the maximum allowable current of the bidirectional DCDC power conversion module, meanwhile, the voltage of the output end of the bidirectional DCDC power conversion module is controlled to be lower than the highest voltage of the direct-current charging pile and is kept constant, and then the voltage is boosted through the bidirectional DCDC power conversion module;

c) Under an alternating-current slow charging mode, an alternating-current charging socket is connected to an alternating-current charging pile, the vehicle control unit controls the battery high-voltage relay and the first high-voltage relay to be closed, and other high-voltage relays are disconnected to charge the high-voltage battery pack; in the charging process, the vehicle control unit is responsible for finishing the confirmation of the slow charging process and outputting the allowed slow charging current according to the national standard protocol; the alternating current charger obtains the allowed slow charging current at the moment from the communication network of the whole vehicle, and adjusts the voltage at the output end of the alternating current charger;

d) Under the rapid power supply mode, the direct-current charging gun is connected to a battery of a charged vehicle, the rapid power supply mode is selected from the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the high-voltage battery pack rapidly charges the charged vehicle; in the charging process, the direct current charging gun control board finishes CAN communication between a mobile charging vehicle and a charged vehicle, obtains the maximum discharging current of the high-voltage battery pack from a whole vehicle communication network, adjusts the outlet end voltage of the bidirectional DCDC power supply conversion module so as to control the output current, and at the moment, the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the charged vehicle, so that the rapid direct current charging of the charged vehicle is realized;

e) Under the health degree detection mode, the direct-current charging gun is connected to a battery of a charged vehicle, the health degree detection mode is selected in the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the battery health degree of the charged vehicle is detected by using the mobile charging vehicle; in the charging process, the vehicle control unit adjusts the maximum discharging current of the high-voltage battery pack in real time, so that the maximum output current of the outlet end of the DCDC power supply conversion module is limited, a charged vehicle is charged according to a specific pulse current mode, parameters of the battery are updated iteratively by using a recursive least square method according to the voltage response of the charged vehicle, the SOC and the polarization voltage are estimated in a micro scale by using a Kalman filtering algorithm, the battery capacity is estimated in a macro scale, and the health degree of the battery is finally obtained;

f) Under the alternating current output mode, the alternating current output socket is connected to an electric appliance needing power supply;

under a first direct current charging mode, a second direct current charging mode, an alternating current slow charging mode, a quick power supplementing mode and a health degree detection mode, a battery high-voltage relay protects a high-voltage battery pack from overcurrent damage in the charging and discharging process;

In step e), the battery health of the charged vehicle is detected in a health detection mode, and the method specifically comprises the following steps: 1) Pre-storing SOC-open circuit voltage curves of various types of batteries in the vehicle controller;

2) A direct current charging gun of the mobile charging vehicle is connected with a quick charging port of a vehicle to be charged, a health degree detection mode is selected in a touch liquid crystal display, and a charging start button is pressed;

3) Acquiring the type and rated capacity parameters of the battery, and calling an SOC-open circuit voltage curve of the battery of the corresponding type from the vehicle controller;

4) The maximum output current of the outlet end of the bidirectional DCDC power conversion module is adjusted through the direct-current charging gun control panel, the charging current of a charged vehicle is controlled, and the charging current comprises the following stages:

i. the initial zero-current stage lasts for 10-40 seconds to obtain the voltage of a battery of a charged vehicle as an open-circuit voltage when the vehicle is electrified;

the pulse current excitation and zero current stage is used for identifying the initial value of the parameters of the battery of the charged vehicle, the pulse current excitation is the smaller value of the required current of the charged vehicle and the discharge multiplying power of the high-voltage battery pack 1C, the pulse duration is between 5 and 15 seconds, and the zero current duration is between 40 and 100 seconds;

iii, a square wave current excitation stage, which is used for calculating the SOC of the battery of the charged vehicle, the equivalent circuit model battery parameters and the battery capacity on line, so as to realize the online detection of the health degree of the battery of the charged vehicle, wherein the square wave period is between 30 and 60 seconds, the duty ratio is 20 to 70 percent, the peak value of the square wave is the smaller value of the required current of the charged vehicle and the maximum discharge current of the high-voltage battery pack, and the valley value of the square wave adopts non-zero current, and the range is 4 to 10A;

5) Acquiring the battery charging current and the battery voltage of a charged vehicle through a whole vehicle communication network, and estimating the SOC and the polarization voltage on a micro scale by using Kalman filtering;

6) Because the ohmic internal resistance of the battery is mainly reflected in a high frequency band, and the polarization internal resistance and the polarization capacitance frequency band are lower, the battery parameters are iteratively updated by using a recursive least square method;

7) Estimating the battery capacity on a macroscopic scale by using Kalman filtering according to the SOC and the polarization voltage of the battery obtained in the step 5), and calculating the battery health degree by using the battery capacity;

8) And 4) repeating the steps to 7), and performing reliability evaluation on the battery health degree by adopting two evaluation indexes, and finishing charging when the two evaluation indexes are met.

In the step 1), the SOC-open circuit voltage curves of the various batteries include SOC-open circuit voltage curves of lead-acid batteries, ternary material batteries, lithium iron phosphate batteries, nickel-metal hydride batteries, lithium manganate batteries, cobalt acid batteries, polymer lithium ion batteries and lithium titanate batteries.

In the step 5), the battery SOC and the polarization voltage are estimated by Kalman filtering at a microscopic scale; the method specifically comprises the following steps:

i. the state equation of the battery is expressed as:

wherein, X _k Is the battery state quantity at the k-th time, A _k And B _k Respectively, the coefficient matrix of the state equation at the k-th moment, U _p,k-1 And U _p,k Polarization voltages at time k-1 and k, respectively, SOC _k-1 And SOC _k The state of charge SOC, T of the battery at the k-1 th time and the k-th time _s For a sampling interval, R _p,k And C _p,k Respectively the polarization resistance and the polarization capacitance at the kth moment, cn is the battery capacity, X _k-1 Is the battery state quantity at the k-1 th time, I _k-1 The current at the k-1 th moment is positive when the battery is discharged and negative when the battery is charged, and Q _k-1 The covariance of the system process noise at the k-1 moment;

the observed quantity of the state equation is the battery output voltage U at the kth moment _out,k The observation equation is:

wherein H is the coefficient matrix of the observation equation, R _0,k And U _OC,k Respectively the ohmic internal resistance and the open-circuit voltage of the battery at the k-th moment _k Is the current at the k-th time, R _k-1 Observing the covariance of noise for the system at the k-1 moment;

based on the battery charging current and the battery voltage of the vehicle being charged,calculating the battery state quantity X at the k-th time _k Is estimated a priori

Wherein the content of the first and second substances,

the optimal estimation of the battery state quantity at the k-1 moment is carried out;

calculating the system prior covariance P at time k _k|k-1 ：

P _k|k-1 ＝A _k P _k-1|k-1 A _k ^T +Q _k-1

Wherein, P _k-1|k-1 The system prior covariance at the k-1 time;

calculating a Kalman filter gain K at time K _k ：

K _k ＝P _k|k-1 H ^T (HP _k|k-1 H ^T +R _k ) ^-1

Wherein R is _k Observing noise covariance for the system at the kth moment;

v. calculating an optimal estimate of the battery state quantity of the state equation of the battery at the k-th time

The battery state quantity includes SOC and polarization voltage, and is estimated by optimal estimation

Obtaining the SOC and the polarization voltage of the battery at the kth moment;

calculating the optimal estimated covariance P at time k _k|k ：

P _k|k ＝(E-K _k H)P _k|k-1

Wherein E is an identity matrix;

updating the system process noise covariance Q at time k _k ：

Updating the system observed noise covariance R at time k _k ：

In step 6), the battery parameters including the ohmic internal resistance R of the battery are processed by using a recursive least square method ₀ Internal polarization resistance R _p And a polarization capacitor C _p Performing iterative updating, comprising the steps of:

i. the iterative formula is:

wherein z is _k ＝U _OC,k -U _out,k

Setting:

wherein z is _k-1 ＝U _OC,k-1 -U _out,k-1 ，I _k-1 Is the battery current at time k-1;

calculating a least squares covariance matrix P at time k _θ,k :

Wherein, P _θ,k-1 The covariance matrix is the least square covariance matrix at the k-1 moment, and lambda is a forgetting factor;

calculating a least squares gain matrix K for the kth time instant _θ,k :

v. calculating the battery parameter θ at the k-th moment _k :

Wherein theta is _k-1 The battery parameters at the k-1 time comprise the ohmic internal resistance R of the battery ₀ Internal polarization resistance R _p And a polarization capacitor C _p Then, the updated battery parameters are:

in step 7), the Kalman filtering estimates the battery capacity at a macroscopic scale, and calculates the battery health degree by using the battery capacity, comprising the following steps:

i. macroscopic time scale parameter initialization:

setting a battery capacity initial value Cn ₀ Initial value of covariance of capacity error P _Cn,0 Initial value of noise Q in capacity estimation process _Cn,0 And observation of

Initial value of noise R _Cn,0 ；

Macroscopic timescale initiation:

defining a macroscopic time scale length L, a microscopic time scale k =1: l, the range of L is 80-120, when the microscopic time scale k = L, the macroscopic time scale is started, the microscopic time scale k =1, and a new round of microscopic time scale calculation is started; at the mth macroscopic timescale step definition:

equation of state for micro time scale cells: x is the number of _m,k ＝F(x _m,k-1 ,Cn _m )

Equation of state for macroscopic time scale cells: cn _m ＝Cn _m-1

The observation equation: y is _m,k ＝H(x _m,k-1 ,Cn _m )

Wherein x is _m,k-1 And x _m,k The state quantities of the battery at the microscopic k-1 and k moments in the macroscopic mth stage respectively, including the SOC and the polarization voltage of the battery, are obtained in the step 5), y _m,k Is observed quantity at the microscopic kth time in the macroscopic mth stage, cn _m-1 And Cn _m Respectively represent the battery capacity of the m-1 th and m-th stages of the macro scale;

macroscopic timescale time update:

predicting capacity prior state of macro m-1 stage

Predicting macroscopic m-1 stage capacity error prior covariance

Wherein Q is _Cn,m-1 And P _Cn,m-1 Respectively estimating process noise and capacity error covariance for the m-1 stage capacity;

volume estimation observation matrix calculation:

the observed equation of the capacity estimation process is terminal voltage U _out,L Calculating the formula:

U _out,L ＝U _OC,L +U _p,L +R _0,L ×I _L

wherein, U _OC,L For open circuit voltage, U _p,L Is a polarization voltage, R _0,L Is the internal resistance of the battery, I _L Is the battery current;

the extended Kalman filter solves the estimation problem of a nonlinear system by linearizing the nonlinear system, namely, the state equation and an observation equation are linearized to obtain a state equation Jacobian matrix:

A _Cn ＝1

the jacobian matrix of the observation equation is calculated by an iterative formula:

(1) Calculating the posterior estimate of the capacity derivative of the microscopic k-1 time equation at the macroscopic mth stage

Wherein the content of the first and second substances,

K _m,k-1 respectively carrying out prior estimation on a capacity derivative by a state equation at the microscopic k-1 moment in the mth stage of the macro, and carrying out a derivative and Kalman gain on the capacity by an observation equation;

(2) Calculating a priori estimate of the capacity derivative of the state equation at the mth moment of the macro phase at the kth moment of the micro phase

(3) Calculating the derivative of the observation equation at the mth stage and the kth moment of the macroscopic view to the capacity

When iteration is carried out until the microscopic time scale k = L, the iteration process is skipped, and the derivative value of the observation equation at the last moment of the microscopic time scale to the capacity is the Jacobian matrix corresponding to the observation matrix required by the next macroscopic time scale calculation:

m, k and L are natural numbers;

macro time scale measurement update:

(1) Computing the macroscopic mth stage Kalman gain K _Cn,m ：

(2) Calculating the battery capacity Cn of the mth stage of the macroscopic _m ：

(3) Computing the macroscopic mth stage error covariance P _Cn,m ：

Calculating the SOH of the battery on line:

and taking the ratio of the estimated capacity value to the initial capacity value as a battery health degree SOH, and calculating the battery health degree SOH as follows:

and (3) inputting the battery capacity estimated in the current macro scale step 7) v (2) into a micro time scale in the next macro scale, and updating the battery capacity Cn in the state equation of the battery in the step 5) i for SOC and polarization voltage estimation.

In step 8), two conditions should be simultaneously met at the moment when the charging of the charged vehicle stops: 1. the charged vehicle is charged with enough electric quantity, and the result of the battery health degree of the charged vehicle is reliable; based on the above two points, the charging stop time determination process is as follows:

i. and (3) judging whether the charged electric quantity reaches the required electric quantity:

when the charged amount of electricity reaches the set ratio Q of the initial capacity of the battery _th The method comprises the following steps:

considering that condition one is satisfied, then step 8) ii is executed, otherwise, charging is continued, Q _th Is 20 to 40 percent, wherein,

is composed of

The battery integrates the accumulated charge amount in ampere-hour,

Cn ₀ initial capacity;

and ii, evaluating the reliability of the SOH:

the reliability evaluation of the estimated battery health SOH was performed from two evaluation indexes: 1) The increment of mean square error between the terminal voltage measured value and the estimated value is less than the variance increment threshold xi _th (ii) a 2) The SOH of the battery obtained by the SOC estimation curve and the ampere-hour cumulant increment and the SOH of the battery obtained by the algorithm estimation are smaller than the SOH change amplitude threshold xi _SOH,th (ii) a And simultaneously satisfying evaluation indexes 1) and 2), the result of the SOH is considered to be reliable, and charging is stopped.

The increment of the mean square error between the measured value and the estimated value of the terminal voltage on the macroscopic time scale is used as a basic index of the evaluation index 1), and the basic index is as follows:

wherein, U _out,m,k And y _m,k Respectively a terminal voltage measured value and an observed quantity at a microscopic kth time in a macroscopic mth stage, and a terminal voltage measured value U at a microscopic kth time in a macroscopic mth stage _out,m,k K =1,2,3.. L, obtained by CAN communication;

when the absolute values of 3-10 continuous macro time scale mean square error increments are all smaller than the variance increment threshold xi _th The method comprises the following steps:

|ξ _m -ξ _m-1 |＜ξ _th

considered to satisfy evaluation index 1), variance increment threshold ξ _th In the range of 10 ^-5 ～10 ^-3 Where i =1,2,3 _m And xi _m-1 Terminal voltage mean square deviations on the mth and mth-1 macroscopic time scales respectively;

taking the absolute value of the difference value of two SOH results on a macroscopic time scale as a basic index of an evaluation index 2), and when the difference value of SOH results on 3-10 continuous macroscopic scales is smaller than a threshold xi of SOH change amplitude as shown in the following formula _SOH,th Threshold value xi for change amplitude of SOH _SOH,th The range is 2% -5%:

the evaluation index 2) is considered to be satisfied, wherein the calculated expression of the battery health degree SOH' obtained by the ampere-hour cumulative amount increment is as follows:

in the formula, SOC _t And SOC ₀ Respectively estimated SOC and initial SOC value at the moment;

and simultaneously meeting the evaluation indexes 1) and 2), considering that the result of the health degree of the battery is reliable, and stopping charging.

The invention has the advantages that:

(1) The invention provides a novel multifunctional mobile charging vehicle structure, which not only can charge a charging vehicle by utilizing various charging piles, but also can meet the power supplementing requirements of various electric vehicles through alternating current slow charging and direct current fast charging, and can realize the rapid detection of the health degree of a battery of a charged vehicle;

(2) The integration level of the mobile charging vehicle system is high, and the voltage rising and reducing operations of the mobile charging vehicle can be completed only by using one bidirectional DCDC power supply conversion module, so that the charging of a high-voltage battery pack and the discharging of a charged vehicle are completed;

(3) According to the invention, the on-line detection of the health degree of the vehicle-mounted battery of the new energy automobile can be realized only through the information of the battery of the charged vehicle and the information of the charging process, and long-term battery life cycle test and full charge and discharge test are not required, so that the detection cost and the detection time are greatly reduced;

(4) The battery health degree detection method disclosed by the invention combines a multi-time scale extended Kalman filtering algorithm and a recursive least square method, so that the battery parameter identification and battery health degree detection precision are effectively improved; meanwhile, the detection stopping condition is set, so that the reliability and stability of the health degree result of the battery are ensured;

(5) The mobile charging vehicle adopts integrated heat management, and the high-voltage battery pack and the bidirectional DCDC power supply conversion module share one outdoor heat exchanger to ensure the heat dissipation of the high-voltage battery pack and the bidirectional DCDC power supply conversion module;

(6) The low-level stage excited by the square wave current adopts non-zero current, so that the charging current of the charged vehicle is always positive during the detection period, the battery discharge caused by the high-power electricity consumption of the electric appliance of the charged vehicle is prevented, and the phenomenon of inaccurate detection result is avoided.

Drawings

FIG. 1 is a block diagram of a mobile charging cart capable of detecting the health of a battery according to the present invention;

FIG. 2 is a block diagram of a vehicle communication network of the mobile charging vehicle capable of detecting battery health according to the present invention;

FIG. 3 is a schematic diagram of current excitation in a health detection mode for one embodiment of a mobile charging cart capable of detecting battery health according to the present invention;

FIG. 4 is a schematic view of a thermal management system of one embodiment of a mobile charging cart capable of detecting battery health in accordance with the present invention;

FIG. 5 is a flow chart of one embodiment of a mobile charging cart capable of detecting battery health according to the present invention;

fig. 6 is a flowchart illustrating a charging stop determination process of the mobile charging cart capable of detecting the health of the battery according to an embodiment of the present invention.

Detailed Description

The invention will be further elucidated by means of specific embodiments in the following with reference to the drawing.

As shown in fig. 1, the mobile charging cart capable of detecting the health degree of the battery of the present embodiment includes: the high-voltage battery pack comprises a high-voltage battery pack, a first distribution box, a second distribution box, a bidirectional Direct Current to Direct Current (DCDC) power conversion module, a Direct Current to Alternating Current (DCAC) power conversion module, an AC charger, an AC output socket, an AC charging socket, a first DC charging socket, a second DC charging socket, an air switch, a low-voltage power supply module, a charging start button, an emergency stop button, a DC charging gun, a thermal management system, a vehicle control module, a touch liquid crystal screen and a data recording module; the high-voltage battery pack is respectively connected to the bidirectional DCDC power conversion module, the alternating current charger, the first direct current charging socket, the DCAC power conversion module and the low-voltage power supply module through the first distribution box; the bidirectional DCDC power conversion module is respectively connected to the direct-current charging gun, the second direct-current charging socket and the thermal management system through a second distribution box; the alternating current charger is connected to the alternating current output socket; the DCAC power conversion module is connected to the AC output socket; the line low-voltage power supply module is respectively connected to the vehicle control module, the touch liquid crystal screen, the data recording module and the thermal management system;

the vehicle control module comprises a first direct current charging socket control panel, a second direct current charging socket control panel, a direct current charging gun control panel and a vehicle control unit, wherein communication modules arranged in the first direct current charging socket control panel, the second direct current charging socket control panel and the direct current charging gun control panel are respectively connected with communication lines of a first direct current charging socket, a second direct current charging socket and a direct current charging gun, the first direct current charging socket control panel, the direct current charging gun control panel, the vehicle control unit, a high-voltage battery pack, a DCAC power conversion module, a bidirectional DCDC power conversion module, an alternating current charger, a data recording module, a compressor and a PTC heater in a touch liquid crystal screen and a heat management system are respectively provided with respective communication modules and have communication functions, and all the communication modules are mutually connected to form a vehicle communication network of the mobile charging vehicle, as shown in figure 2; the whole vehicle communication network comprises a CAN bus communication network and an RS485 bus communication network, wherein the CAN bus communication network of the mobile charging vehicle comprises a high-voltage battery pack, a first direct-current charging socket, a direct-current charging gun, a second direct-current charging socket, a compressor, a PTC heater, an alternating-current charger, a data recording module and a whole vehicle controller; the RS485 communication network comprises a first direct current charging socket control panel, a direct current charging gun control panel, a second direct current charging socket control panel, a bidirectional DCDC power conversion module, a DCAC power conversion module and a touch-controllable liquid crystal screen, wherein CAN-H and CAN-L in the figure 2 are respectively an H line and an L line of CAN communication; RS485-A and RS485-B are respectively line A and line B of RS485 communication network;

the first distribution box comprises a first distribution box shell, a high-voltage battery pack interface, a bidirectional DCDC power conversion module interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface, a low-voltage power supply module interface, a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay; the first distribution box is hollow, a high-voltage battery pack interface, a bidirectional DCDC power conversion module input interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface and a low-voltage power supply module interface are respectively arranged on the surface of the first distribution box, and a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay are arranged in the first distribution box; the output end of the high-voltage battery pack is connected to a high-voltage battery pack interface, the high-voltage battery pack interface is connected to an input interface of the bidirectional DCDC power conversion module through a battery high-voltage relay, the high-voltage battery pack interface is connected to an alternating current charger interface through the battery high-voltage relay and a first high-voltage relay, the high-voltage battery pack interface is connected to a first direct current charging socket interface through the battery high-voltage relay and a second high-voltage relay, and the high-voltage battery pack interface is also connected to a DCAC power conversion module interface and a low-voltage power supply module interface respectively; the input interface of the bidirectional DCDC power supply conversion module is connected to the input end of the bidirectional DCDC power supply conversion module; the interface of the alternating current charger is connected to the alternating current charger; the first direct current charging socket interface is connected to the first direct current charging socket; the DCAC power conversion module interface is connected to the DCAC power conversion module; the low-voltage power supply module interface is connected to the low-voltage power supply module through an air switch;

the second distribution box comprises a second distribution box shell, a bidirectional DCDC power conversion module output interface, a second direct current charging socket interface, a thermal management system interface, a direct current charging gun interface, a third high-voltage relay and a fourth high-voltage relay; the second distribution box shell is hollow, the surface of the second distribution box shell is respectively provided with a bidirectional DCDC power conversion module output interface, a second direct-current charging socket interface, a thermal management system interface and a direct-current charging gun interface, and a third high-voltage relay and a fourth high-voltage relay are arranged in the second distribution box shell; the output end of the bidirectional DCDC power supply conversion module is connected to the output interface of the bidirectional DCDC power supply conversion module; the output interface of the DCDC power conversion module is connected to the second direct-current charging socket interface; the output interface of the DCDC power supply conversion module is connected to the interface of the direct current charging gun through a third high-voltage relay; the output interface of the DCDC power supply conversion module is connected to the interface of the thermal management system through a fourth high-voltage relay; the second direct current charging socket interface is connected to the second direct current charging socket; the direct current charging gun interface is connected to the direct current charging gun through a charging start button and an emergency stop button; the thermal management system interface is connected to a compressor and a thermistor (PTC) heater in the thermal management system;

in a first direct current charging mode, a first direct current charging socket is connected to a direct current charging pile with the highest voltage of 750v to charge a high-voltage battery pack, a vehicle control unit controls a battery high-voltage relay and a second high-voltage relay to be closed, and other high-voltage relays are opened; in the charging process, the first direct current charging socket control panel acquires real-time voltage, state of Charge (SOC) and maximum charging current information of the high-voltage battery pack from a whole vehicle communication Network in real time, and completes Controller Area Network (CAN) communication between the mobile charging vehicle and a charging pile, wherein the communication standard is GBT 27930-2015 communication protocol between an electric vehicle non-vehicle-mounted conductive charger and a battery management system, so that the charging pile outputs current to Charge the high-voltage battery pack, and simultaneously, the information is uploaded to a touch liquid crystal display through an RS485 bus communication Network;

in a second direct-current charging mode, a second direct-current charging socket is connected to a direct-current charging pile with the highest voltage of 500v to charge a high-voltage battery pack, the vehicle control unit controls a battery high-voltage relay and a fourth high-voltage relay to be closed, and other high-voltage relays are disconnected; in the charging process, the second direct-current charging socket control board acquires the real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from a finished automobile communication network, the maximum charging current of the second direct-current charging mode is the smaller value of the maximum charging current of the high-voltage battery pack and the maximum allowable current of the bidirectional DCDC power conversion module, meanwhile, the voltage of the output end of the bidirectional DCDC power conversion module is controlled to be lower than the highest voltage of the direct-current charging pile and is kept constant, and then the voltage is boosted through the bidirectional DCDC power conversion module; the second direct current charging socket control panel acquires real-time information of the high-voltage battery pack from a CAN bus communication network, CAN communication between the mobile charging car and the charging pile is completed, the communication standard is GBT 27930-2015, and the outlet end of the bidirectional DCDC power supply conversion module is controlled to keep constant voltage through an RS485 bus communication network, so that the charging pile outputs current to charge the high-voltage battery pack; meanwhile, information is uploaded to the touch liquid crystal screen through an RS485 bus communication network;

under an alternating-current slow charging mode, an alternating-current charging socket is connected to an alternating-current charging pile, the vehicle control unit controls the battery high-voltage relay and the first high-voltage relay to be closed, and other high-voltage relays are disconnected to charge the high-voltage battery pack; in the charging process, the vehicle control unit is responsible for finishing the confirmation of the slow charging process and outputting the allowed slow charging current according to the national standard protocol; the alternating current charger obtains the allowed slow charging current at the moment from the communication network of the whole vehicle, and adjusts the voltage of the output end of the alternating current charger; meanwhile, the vehicle controller completes the confirmation of the slow charging process according to GBT 18487.1-2015, and uploads the allowed slow charging current to the CAN bus communication network; the alternating current charger adjusts the direct current voltage of the output end so as to realize slow charging of the high-voltage battery pack;

under the rapid power supply mode, the direct-current charging gun is connected to a battery of a charged vehicle, the rapid power supply mode is selected from the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the high-voltage battery pack rapidly charges the charged vehicle; in the charging process, the direct current charging gun control board finishes CAN communication between a mobile charging vehicle and a charged vehicle, obtains the maximum discharging current of the high-voltage battery pack from a whole vehicle communication network, adjusts the outlet end voltage of the bidirectional DCDC power supply conversion module so as to control the output current, and at the moment, the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the charged vehicle, so that the rapid direct current charging of the charged vehicle is realized; the direct current charging gun control panel simulates a charging pile to complete CAN communication with a charged vehicle, obtains the maximum discharging current of the high-voltage battery pack from a CAN bus communication network, controls the outlet end voltage of the bidirectional DCDC power supply conversion module through an RS485 bus so as to control the output current, and the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the charged vehicle so as to realize rapid direct current power supplement for the charged vehicle; meanwhile, information is uploaded to the touch liquid crystal screen through an RS485 bus communication network;

under the health degree detection mode, the direct-current charging gun is connected to a battery of a charged vehicle, the health degree detection mode is selected in the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the battery health degree of the charged vehicle is detected by using the mobile charging vehicle; in the charging process, the vehicle control unit adjusts the maximum discharging current of the high-voltage battery pack in real time, the current range is 0 to the smaller value of the required current of the charged vehicle and the maximum discharging current of the high-voltage battery pack, so that the maximum output current of the outlet end of the DCDC power supply conversion module is limited, the charged vehicle is charged according to a specific pulse current form, and the health degree of the charged vehicle is detected according to the voltage response of the charged vehicle; the direct current charging gun control panel acquires the maximum discharging current information of the high-voltage battery pack from a CAN bus communication network, simulates a charging pile to complete CAN communication with a charged vehicle, and controls the outlet end voltage of a bidirectional DCDC power conversion module through an RS485 bus so as to control the output current to detect the health degree of the battery pack of the charged vehicle, and the current excitation for realizing the battery health degree detection is shown in an attached figure 3; meanwhile, information is uploaded to the touch liquid crystal screen through an RS485 bus communication network;

As shown in fig. 4, the thermal management system includes: the system comprises a compressor, an outdoor heat exchanger, a thermal expansion valve, a plate heat exchanger, a PTC heater, a first temperature sensor, a second temperature sensor, a water pump and a three-way valve; wherein, the mobile charging car adopts integrated form thermal management return circuit including coolant liquid return circuit and refrigerant return circuit: in the cooling liquid loop, one side of the high-voltage battery pack is connected to the PTC heater through a water pipe, a first temperature sensor is arranged on the water pipe connecting the high-voltage battery pack to the PTC heater, and the PTC heater is connected to a first outlet of the three-way valve; one side of the bidirectional DCDC power conversion module is connected to a second outlet of the three-way valve through a pipeline, a second temperature sensor is arranged on the pipeline connecting the bidirectional DCDC power conversion module to the second outlet of the three-way valve, the other side of the high-voltage battery pack and the other side of the bidirectional DCDC power conversion module are connected with one side of a water pump, the other side of the water pump is connected with a first interface of the plate type heat exchanger, and a second interface of the plate type heat exchanger is connected with an inlet of the three-way valve; in the refrigerant loop, the outlet of the compressor, the outdoor heat exchanger and the inlet of the thermostatic expansion valve are sequentially connected, the outlet of the thermostatic expansion valve is connected with the third interface of the plate heat exchanger, and the fourth interface of the plate heat exchanger is connected with the inlet of the compressor. The first temperature sensor, the second temperature sensor, the three-way valve and the water pump are respectively connected with a vehicle controller of a vehicle control module through control lines; the thermal management system is used for keeping the high-voltage battery pack and the bidirectional DCDC power conversion module in a proper working temperature range.

The data recording module is connected to an upper computer through a communication module; acquiring charging information of a charged vehicle from a whole vehicle communication network, wherein the charging information comprises battery type, SOC, battery voltage, battery current, battery temperature and battery monomer maximum voltage information; and the system is stored in an upper computer and used for recording the battery health degree of the charged vehicle and constructing a new energy automobile charging database.

The touch liquid crystal screen is used for displaying information of the high-voltage battery pack, the bidirectional DCDC power supply conversion module and the vehicle control module; meanwhile, the touch liquid crystal display can be used for setting thresholds of overvoltage early warning, undervoltage early warning and overtemperature early warning of the bidirectional DCDC power supply conversion module; when the direct current charging gun is connected with a charged vehicle, the touch liquid crystal screen is also used for displaying charging information of the charged vehicle and selecting different charging modes, including a quick power supply mode and a health degree detection mode.

The mobile charging cart capable of detecting the battery health degree of the embodiment detects the battery health degree of the vehicle to be charged in the health degree detection mode, as shown in fig. 5, and includes the following steps:

1) The SOC-open-circuit voltage curves of various types of batteries are stored in the vehicle control unit in advance, and comprise SOC-open-circuit voltage curves of lead-acid batteries, ternary material batteries, lithium iron phosphate batteries, nickel-hydrogen batteries, lithium manganate batteries, cobalt acid batteries, polymer lithium ion batteries and lithium titanate batteries;

3) Acquiring the type and rated capacity parameters of the battery through CAN bus communication, and calling an SOC-open circuit voltage curve of the battery of the corresponding type from the whole vehicle controller;

4) The maximum output current of the outlet end of the bidirectional DCDC power supply conversion module is adjusted through the direct current charging gun control panel, and the charging current of the charged vehicle is controlled; as shown in fig. 3, the charging current includes the following phases:

i. the initial zero current stage is maintained for 20 seconds to obtain the battery voltage of the charged vehicle as the open-circuit voltage;

ii, pulse current excitation and zero current stage, which is used for identifying the initial value of the parameters of the battery of the charged vehicle, wherein the pulse current excitation is the smaller value of the required current of the charged vehicle and the discharge multiplying power of the high-voltage battery pack 1C, the pulse time length is 10 seconds, and the zero current time length is 60 seconds;

charging for 20 seconds by the charging current required by the charged vehicle, then charging for 20 seconds by 10A current, repeating the square wave current excitation for 5 times, then performing constant current charging for 80 seconds by the charging current required by the charged vehicle, and then continuously repeating the excitation current for 280 seconds until the charging of the charged vehicle is finished;

5) The method comprises the following steps of obtaining battery charging current and battery voltage of a charged vehicle through a whole vehicle communication network, and estimating SOC and polarization voltage on a micro scale by using Kalman filtering, wherein the method specifically comprises the following steps:

i. the state equation of the battery is expressed as:

wherein, X _k Is the battery state quantity at the k-th time, A _k And B _k Respectively, the coefficient matrix of the state equation at the k-th moment, U _p,k-1 And U _p,k Polarization voltages at time k-1 and k, respectively, SOC _k-1 And SOC _k Is the state of charge SOC, T of the battery at time k-1 and time k _s For a sampling interval, R _p,k And C _p,k Polarized electricity at the k-th timeResistance and polarization capacitance, cn being the cell capacity, X _k-1 Is the battery state quantity at the k-1 th time, I _k-1 The current at the k-1 th time is positive when the battery is discharged, negative when the battery is charged, and Q _k-1 The covariance of the system process noise at the k-1 moment;

calculating a battery state quantity X at the k-th time from a battery charging current and a battery voltage of the charged vehicle _k Is estimated a priori

Wherein the content of the first and second substances,

calculating the system prior covariance P at time k _k|k-1 ：

P _k|k-1 ＝A _k P _k-1|k-1 A _k ^T +Q _k-1

Wherein, P _k-1|k-1 The system prior covariance at the k-1 time;

calculating a Kalman filter gain K at time K _k ：

K _k ＝P _k|k-1 H ^T (HP _k|k-1 H ^T +R _k ) ^-1

Wherein R is _k Observing noise covariance for the system at the kth time;

v. calculating optimal estimate of battery state quantity of state equation of battery at k-th time

The battery state quantity comprises the SOC and the polarization voltage, so that the SOC and the polarization voltage of the battery at the k-th moment are obtained;

calculating the optimal estimated covariance P at time k _k|k ：

P _k|k ＝(E-K _k H)P _k|k-1

Wherein E is an identity matrix;

updating the system process noise covariance Q at time k _k ：

Updating the system observed noise covariance R at time k _k ：

6) Because the ohmic internal resistance of the battery is mainly reflected in a high frequency band, and the polarization internal resistance and the polarization capacitance frequency band are lower, the recursive least square method is utilized to carry out treatment on the battery parameters including the ohmic internal resistance R of the battery ₀ Internal polarization resistance R _p And a polarization capacitor C _p Performing iterative updating:

i. the iterative formula is:

wherein z is _k ＝U _OC,k -U _out,k

ii, setting:

calculating a least squares covariance matrix P at time k _θ,k :

Wherein, P _θ,k-1 Is a least square covariance matrix at the k-1 moment, and lambda is a forgetting factor;

calculating a least squares gain matrix K at time K _θ,k :

v. calculating the battery parameter θ at the k-th moment _k :

Wherein theta is _k-1 If the battery parameter is the battery parameter at the k-1 moment, the updated battery parameter is:

7) Estimating the battery capacity on a macroscopic scale by using Kalman filtering according to the SOC and the polarization voltage of the battery obtained in the step 5), wherein the method comprises the following steps:

i. macroscopic time scale parameter initialization:

setting the initial value Cn of the battery capacity ₀ Initial value of covariance of capacity error P _Cn,0 Initial value of noise Q in capacity estimation process _Cn,0 And observing the initial value R of the noise _Cn,0 ；

Macro time scale start-up:

defining a macroscopic time scale length L, a microscopic time scale k =1: l, when the microscopic time scale k = L, starting the macroscopic time scale, starting the microscopic time scale k =1, and starting a new round of microscopic time scale calculation; at the mth macroscopic timescale step definition:

equation of state for microscopic time scale cells: x is the number of _m,k ＝F(x _m,k-1 ,Cn _m )

Equation of state for macroscopic time scale cells: cn _m ＝Cn _m-1

The observation equation: y is _m,k ＝H(x _m,k-1 ,Cn _m )

Wherein x is _m,k-1 And x _m,k The state quantities of the battery at the microscopic k-1 and k moments of the macroscopic mth stage and the microscopic k-1 and k moments respectively, including the SOC and the polarization voltage of the battery, are obtained in the step 5), y _m,k Is observed quantity at the microscopic kth time in the macroscopic mth stage, cn _m-1 And Cn _m Respectively representing the cell capacity of the m-1 th and m-th macroscopic stages;

macroscopic timescale time update:

predicting capacity prior state of macro m-1 stage

Predicting macroscopic m-1 stage capacity error prior covariance

Wherein Q _Cn,m-1 And P _Cn,m-1 Respectively estimating process noise and capacity error covariance for the m-1 stage capacity;

capacity estimation observation matrix calculation:

U _out,L ＝U _OC,L +U _p,L +R _0,L ×I _L

U _OC,L is open circuit voltage, U _p,L Is a polarization voltage, R _0,L Is the internal resistance of the battery, I _L Is the battery current;

extended Kalman Filtering solves the estimation problem of nonlinear systems by linearizing them, i.e. by linearizing the state

Performing Jacobian linearization on the equation and the observation equation to obtain a Jacobian matrix of a state equation:

A _Cn ＝1

the Jacobian matrix of the observation equation is calculated by an iterative formula to obtain:

Wherein, the first and the second end of the pipe are connected with each other,

(2) Calculating the state of the microscopic kth moment in the mth stage of the macroscopicA priori estimation of the derivative of the capacity by the equation

(3) Calculating the derivative of the observation equation at the mth stage and the kth moment of the macro stage to the capacity

When iteration is carried out until the microscopic time scale k =100, jumping out of an iteration process, wherein a derivative value of an observation equation at the last moment of the microscopic time scale to the capacity is a Jacobian matrix corresponding to an observation matrix required by the next macroscopic time scale calculation:

macroscopic timescale measurement update:

(1) Computing a macroscopic mth stage Kalman gain K _Cn,m ：

(3) Computing the macroscopic mth stage error covariance P _Cn,m ：

Calculating the SOH of the battery on line:

and (3) taking the ratio of the estimated capacity value to the initial capacity value as a battery health degree SOH, and calculating the battery health degree SOH as follows:

and (3) inputting the battery capacity obtained by the current macroscopic scale estimation into the microscopic time scale in the next macroscopic scale, and updating the battery capacity parameters in the state equation in the step 5) for SOC and polarization voltage estimation.

8) Repeating 4) -7), until the charging is finished, as shown in fig. 6, the charging stop time of the charged vehicle should simultaneously satisfy two conditions: 1. the charged vehicle is charged with enough electric quantity, and the result of the battery health degree of the charged vehicle is reliable; based on the above two points, the charging stop time determination process is as follows:

i. and executing judgment whether the charged electric quantity reaches the required electric quantity:

when the charged amount of electricity reaches the set ratio Q of the initial capacity of the battery _th When =30%

Considering that the condition one is met, executing 8) ii, and if the condition one is not met, continuing charging;

performing a result reliability evaluation of the battery health SOH:

the evaluation of the reliability of SOH was performed from two evaluation indexes: 1) The increment of mean square error between the terminal voltage measured value and the estimated value is less than the variance increment threshold xi _th ＝10 ^-4 (ii) a 2) SOH obtained by SOC estimation curve and ampere-hour accumulation increment and SOH error obtained by algorithm estimation are smaller than SOH change amplitude threshold xi _SOH,th ＝30％。

wherein k =1,2,3.

When the absolute values of 5 continuous macro time scale mean square error increments are all smaller than the variance increment threshold xi _th When, the estimation result is considered to satisfy the evaluation index 1):

|ξ _m -ξ _m-1 |＜10 ^-4

taking the absolute value of the difference value of two SOH results on a macroscopic time scale as a basic index of the evaluation index 2), and when the difference value of SOH results on 5 continuous macroscopic scales is smaller than a threshold xi of the change amplitude of SOH as shown in the following formula _SOH,th Considered to satisfy evaluation index 2):

and simultaneously meeting the evaluation indexes 1) and 2), the result of the health degree of the battery is considered to be reliable, and the charging is stopped.

Finally, it is noted that the disclosed embodiments are intended to aid in further understanding of the invention, but those skilled in the art will appreciate that: various substitutions and modifications are possible without departing from the spirit and scope of this disclosure and the appended claims. Therefore, the invention should not be limited to the embodiments disclosed, but the scope of the invention is defined by the appended claims.

Claims

1. A mobile charging cart capable of detecting the health degree of a battery, comprising: the system comprises a high-voltage battery pack, a first distribution box, a second distribution box, a bidirectional direct current-direct current DCDC power conversion module, a direct current-alternating current DCAC power conversion module, an alternating current charger, an alternating current output socket, an alternating current charging socket, a first direct current charging socket, a second direct current charging socket, an air switch, a low-voltage power supply module, a charging start button, an emergency stop button, a direct current charging gun, a thermal management system, a vehicle control module, a touch liquid crystal screen and a data recording module; the high-voltage battery pack is respectively connected to the bidirectional DCDC power conversion module, the alternating-current charger, the first direct-current charging socket, the DCAC power conversion module and the low-voltage power supply module through the first distribution box; the bidirectional DCDC power conversion module is respectively connected to the direct-current charging gun, the second direct-current charging socket and the thermal management system through a second distribution box; the alternating current charger is connected to the alternating current output socket; the DCAC power conversion module is connected to the AC output socket; the low-voltage power supply module is respectively connected to the vehicle control module, the touch liquid crystal screen, the data recording module and the thermal management system;

the first distribution box comprises a first distribution box shell, a high-voltage battery pack interface, a bidirectional DCDC power conversion module interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface, a low-voltage power supply module interface, a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay; the first distribution box comprises a first distribution box shell, a second distribution box shell, a third distribution box shell, a fourth distribution box shell and a fourth distribution box shell, wherein the first distribution box shell is hollow, a high-voltage battery pack interface, a bidirectional DCDC power conversion module input interface, an alternating current charger interface, a first direct current charging socket interface, a DCAC power conversion module interface and a low-voltage power supply module interface are respectively arranged on the surface of the first distribution box shell, and a battery high-voltage relay, a first high-voltage relay and a second high-voltage relay are arranged in the first distribution box shell; the output end of the high-voltage battery pack is connected to a high-voltage battery pack interface, the high-voltage battery pack interface is connected to an input interface of the bidirectional DCDC power conversion module through a battery high-voltage relay, the high-voltage battery pack interface is connected to an alternating current charger interface through the battery high-voltage relay and a first high-voltage relay, the high-voltage battery pack interface is connected to a first direct current charging socket interface through the battery high-voltage relay and a second high-voltage relay, and the high-voltage battery pack interface is also connected to a DCAC power conversion module interface and a low-voltage power supply module interface respectively; the input interface of the bidirectional DCDC power supply conversion module is connected to the input end of the bidirectional DCDC power supply conversion module; the interface of the alternating current charger is connected to the alternating current charger; the first direct current charging socket interface is connected to the first direct current charging socket; the DCAC power conversion module interface is connected to the DCAC power conversion module; the low-voltage power supply module interface is connected to the low-voltage power supply module through an air switch; the vehicle control unit is respectively connected with the battery high-voltage relay, the first high-voltage relay and the second high-voltage relay through control lines and is used for controlling the on-off of each high-voltage relay;

the second distribution box comprises a second distribution box shell, a bidirectional DCDC power conversion module output interface, a second direct current charging socket interface, a thermal management system interface, a direct current charging gun interface, a third high-voltage relay and a fourth high-voltage relay; the second distribution box shell is hollow, the surface of the second distribution box shell is respectively provided with a bidirectional DCDC power conversion module output interface, a second direct-current charging socket interface, a thermal management system interface and a direct-current charging gun interface, and a third high-voltage relay and a fourth high-voltage relay are arranged in the second distribution box shell; the output end of the bidirectional DCDC power supply conversion module is connected to the output interface of the bidirectional DCDC power supply conversion module; the output interface of the DCDC power conversion module is connected to the second direct-current charging socket interface; the output interface of the DCDC power supply conversion module is connected to the interface of the direct current charging gun through a third high-voltage relay; the output interface of the DCDC power supply conversion module is connected to the interface of the thermal management system through a fourth high-voltage relay; the second direct current charging socket interface is connected to a second direct current charging socket; the direct current charging gun interface is connected to the direct current charging gun through a charging start button and an emergency stop button; the thermal management system interface is connected to a compressor and a thermistor PTC heater in the thermal management system; the vehicle control unit is respectively connected with the third high-voltage relay and the fourth high-voltage relay through control lines and is used for switching on and off of each high-voltage control relay;

in a first direct current charging mode, a first direct current charging socket is connected to a direct current charging pile, the vehicle control unit controls the battery high-voltage relay and the second high-voltage relay to be closed, and other high-voltage relays are opened to charge the high-voltage battery pack; in the charging process, the first direct current charging socket control panel acquires real-time voltage, state of charge (SOC) and maximum charging current information of the high-voltage battery pack from a whole vehicle communication network in real time, and completes Controller Area Network (CAN) communication between the mobile charging vehicle and the charging pile;

in a second direct-current charging mode, a second direct-current charging socket is connected to a direct-current charging pile with the highest voltage exceeding the highest voltage of the high-voltage battery pack, the vehicle controller controls the battery high-voltage relay and the fourth high-voltage relay to be closed, and other high-voltage relays are opened to charge the high-voltage battery pack; in the charging process, the second direct-current charging socket control board acquires the real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from a finished automobile communication network, the maximum charging current of the second direct-current charging mode is the smaller value of the maximum charging current of the high-voltage battery pack and the maximum allowable current of the bidirectional DCDC power conversion module, meanwhile, the voltage of the output end of the bidirectional DCDC power conversion module is controlled to be lower than the highest voltage of the direct-current charging pile and is kept constant, and then the voltage is boosted through the bidirectional DCDC power conversion module;

under an alternating-current slow charging mode, an alternating-current charging socket is connected to an alternating-current charging pile, the vehicle control unit controls the battery high-voltage relay and the first high-voltage relay to be closed, and other high-voltage relays are disconnected to charge the high-voltage battery pack; in the charging process, the vehicle control unit is responsible for finishing the confirmation of the slow charging process and outputting the allowed slow charging current; the alternating current charger obtains the allowed slow charging current at the moment from the communication network of the whole vehicle, and adjusts the voltage at the output end of the alternating current charger;

under the rapid power supply mode, the direct-current charging gun is connected to a battery of a charged vehicle, the rapid power supply mode is selected from the touch liquid crystal screen, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the high-voltage battery pack rapidly charges the charged vehicle; in the charging process, the direct current charging gun control board finishes CAN communication between a mobile charging vehicle and a charged vehicle, obtains the maximum discharging current of the high-voltage battery pack from a whole vehicle communication network, adjusts the outlet end voltage of the bidirectional DCDC power supply conversion module so as to control the output current, and at the moment, the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the charged vehicle, so that the rapid direct current charging of the charged vehicle is realized;

under the health degree detection mode, the direct-current charging gun is connected to a battery of a charged vehicle, the health degree detection mode is selected in the touch liquid crystal display, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the battery health degree of the charged vehicle is detected by using the mobile charging vehicle; in the charging process, the vehicle control unit adjusts the maximum discharging current of the high-voltage battery pack in real time, so that the maximum output current of the outlet end of the DCDC power conversion module is limited, a charged vehicle is charged in a specific pulse current mode, and the health degree of the charged vehicle is detected according to the voltage response of the charged vehicle;

2. The mobile charging cart capable of detecting battery health of claim 1, wherein the thermal management system comprises: the system comprises a compressor, an outdoor heat exchanger, a thermal expansion valve, a plate heat exchanger, a PTC heater, a first temperature sensor, a second temperature sensor, a water pump and a three-way valve; wherein, the mobile charging car adopts integrated form thermal management return circuit including coolant liquid return circuit and refrigerant return circuit: in the cooling liquid loop, one side of the high-voltage battery pack is connected to the PTC heater through a water pipe, a first temperature sensor is arranged on the water pipe connecting the high-voltage battery pack to the PTC heater, and the PTC heater is connected to a first outlet of the three-way valve; one side of the bidirectional DCDC power supply conversion module is connected to a second outlet of the three-way valve through a pipeline, a second temperature sensor is arranged on the pipeline connecting the bidirectional DCDC power supply conversion module to the second outlet of the three-way valve, the other side of the high-voltage battery pack and the other side of the bidirectional DCDC power supply conversion module are connected with one side of a water pump, the other side of the water pump is connected with a first interface of the plate heat exchanger, and a second interface of the plate heat exchanger is connected with an inlet of the three-way valve; in the refrigerant loop, the outlet of the compressor, the outdoor heat exchanger and the inlet of the thermostatic expansion valve are sequentially connected, the outlet of the thermostatic expansion valve is connected with the third interface of the plate heat exchanger, and the fourth interface of the plate heat exchanger is connected with the inlet of the compressor.

3. The method for implementing a mobile charging vehicle capable of detecting health of battery as claimed in claim 1, wherein the implementing method comprises the following steps:

a) In a first direct current charging mode, a first direct current charging socket is connected to a direct current charging pile, the vehicle control unit controls the battery high-voltage relay and the second high-voltage relay to be closed, and other high-voltage relays are opened to charge the high-voltage battery pack; in the charging process, the first direct-current charging socket control board acquires the real-time voltage, SOC and maximum charging current information of the high-voltage battery pack in real time from the whole vehicle communication network, and completes controller area network CAN communication between the mobile charging vehicle and the charging pile;

d) Under the rapid power supply mode, the direct-current charging gun is connected to a battery of a charged vehicle, the rapid power supply mode is selected from the touch liquid crystal screen, the vehicle control unit controls the battery high-voltage relay and the third high-voltage relay to be closed, other high-voltage relays are disconnected, and the high-voltage battery pack rapidly charges the charged vehicle; in the charging process, the direct current charging gun control board finishes CAN communication between a mobile charging vehicle and a charged vehicle, obtains the maximum discharging current of the high-voltage battery pack from a whole vehicle communication network, adjusts the outlet end voltage of the bidirectional DCDC power supply conversion module so as to control the output current, and at the moment, the actual output current is the smaller value of the maximum discharging current of the high-voltage battery pack and the required current of the charged vehicle, so that the rapid direct current charging of the charged vehicle is realized;

the whole vehicle controller controls the first high-voltage relay, the second high-voltage relay, the third high-voltage relay and the fourth high-voltage relay to be switched on and off, and at most one high-voltage relay in the four high-voltage relays is switched off at the same time, so that the uniqueness of a charging and discharging mode of the mobile charging vehicle is ensured.

4. The implementation manner of claim 3, wherein in the step e), the battery health degree of the charged vehicle is detected in the health degree detection mode, and the method specifically comprises the following steps:

1) Pre-storing SOC-open circuit voltage curves of various types of batteries in the vehicle controller;

i. the initial zero current stage is used for obtaining the battery voltage of the charged vehicle as the open circuit voltage when the vehicle is electrified;

a pulsed current excitation and zero current phase for identifying initial values of charged vehicle battery parameters;

the square wave current excitation stage is used for calculating the SOC of the battery of the charged vehicle, the equivalent circuit model battery parameters and the battery capacity on line so as to realize the on-line detection of the health degree of the battery of the charged vehicle, the peak value of the square wave is the smaller value of the required current of the charged vehicle and the maximum discharge current of the high-voltage battery pack, and the valley value of the square wave adopts non-zero current;

6) Because the ohmic internal resistance of the battery is mainly embodied in a high frequency band, and the polarization internal resistance and the polarization capacitance frequency band are lower, the iterative updating is carried out on the battery parameters by using a recursive least square method;

5. The implementation of claim 4, wherein in step 5), kalman filtering estimates battery SOC and polarization voltage at a microscopic scale; the method specifically comprises the following steps:

i. the state equation of the battery is expressed as:

wherein, X _k Is the battery state quantity at the k-th time, A _k And B _k Are the state equation coefficient matrix at the kth time, U _p,k-1 And U _p,k Polarization voltages at time k-1 and k, respectively, SOC _k-1 And SOC _k The state of charge SOC, T of the battery at the k-1 th time and the k-th time _s For a sampling interval, R _p,k And C _p,k Respectively the polarization resistance and the polarization capacitance at the kth moment, cn is the battery capacity, X _k-1 Is the battery state quantity at the k-1 th time, I _k-1 The current at the k-1 th moment is positive when the battery is discharged and negative when the battery is charged, and Q _k-1 The covariance of the system process noise at the k-1 moment;

wherein H is the coefficient matrix of the observation equation, R _0,k And U _OC,k Ohmic internal resistance of the battery and open-circuit voltage, I, of the battery at the k-th moment _k Is the current at the k-th time, R _k-1 Observing the covariance of noise for the system at the k-1 moment;

Wherein the content of the first and second substances,

calculating the system prior covariance P at time k _k|k-1 ：

P _k|k-1 ＝A _k P _k-1|k-1 A _k ^T +Q _k-1

Wherein, P _k-1|k-1 Is the system prior covariance at the k-1 time;

calculating a Kalman filter gain K at time K _k ：

K _k ＝P _k|k-1 H ^T (HP _k|k-1 H ^T +R _k ) ^-1

Wherein R is _k Observing noise covariance for the system at the kth moment;

calculating the optimal estimated covariance P at time k _k|k ：

P _k|k ＝(E-K _k H)P _k|k-1

Wherein E is an identity matrix;

updating the system process noise covariance Q at time k _k ：

Updating the system observed noise covariance R at time k _k ：

6. The implementation manner of claim 4, wherein in the step 6), the battery parameters comprise ohmic internal resistance R of the battery by using a recursive least square method ₀ Internal polarization resistance R _p And a polarization capacitor C _p Performing iterative updating, comprising the steps of:

i. the iterative formula is:

wherein z is _k ＝U _OC,k -U _out,k

ii, setting:

calculating a least squares covariance matrix P at time k _θ,k :

calculating a least squares gain matrix K at time K _θ,k :

v. calculating the battery parameter θ at the k-th moment _k :

7. the implementation of claim 4 wherein kalman filtering estimates battery capacity at a macro scale and calculates battery health using battery capacity in step 7) comprises the steps of:

i. macroscopic time scale parameter initialization:

setting a battery capacity initial value Cn ₀ Initial value of covariance of capacity error P _Cn,0 Initial value of noise Q in capacity estimation process _Cn,0 And observing the initial value R of the noise _Cn,0 ；

Macroscopic timescale initiation:

defining a macroscopic time scale length L, a microscopic time scale k =1: l, when the microscopic time scale k = L, starting the macroscopic time scale, starting a new round of microscopic time scale calculation when the microscopic time scale k = 1; at the mth macroscopic timescale step definition:

Equation of state for macroscopic time scale cells: cn _m ＝Cn _m-1

The observation equation: y is _m,k ＝H(x _m,k-1 ,Cn _m )

Wherein x is _m,k-1 And x _m,k The state quantities of the battery at the microscopic k-1 and k moments of the macroscopic mth stage and the microscopic k-1 and k moments respectively, including the SOC and the polarization voltage of the battery, are obtained in the step 5), y _m,k Is observed quantity at the microscopic kth time in the macroscopic mth stage, cn _m-1 And Cn _m Respectively represent the battery capacity of the m-1 th and m-th stages of the macro scale;

macro time scale time update:

predicting capacity prior state of macro m-1 stage

Predicting macroscopic m-1 stage capacity error prior covariance

volume estimation observation matrix calculation:

U _out,L ＝U _OC,L +U _p,L +R _0,L ×I _L

wherein, U _OC,L Is open circuit voltage, U _p,L Is a polarization voltage, R _0,L Is the internal resistance of the battery, I _L Is the battery current;

the extended Kalman filtering solves the estimation problem of the nonlinear system by linearizing the nonlinear system, namely, the state equation and the observation equation are subjected to Jacobian linearization to obtain a Jacobian matrix of the state equation:

A _Cn ＝1

and K _m,k-1 Respectively carrying out prior estimation on a capacity derivative by a state equation at the microscopic k-1 moment in the mth stage of the macro, and carrying out a derivative and Kalman gain on the capacity by an observation equation;

m, k and L are natural numbers;

macro time scale measurement update:

(1) Computing a macroscopic mth stage Kalman gain K _Cn,m ：

(2) Calculating the macroscopic mth stage cell capacity Cn _m ：

(3) Computing the macroscopic mth stage error covariance P _Cn,m ：

Calculating the SOH of the battery on line:

estimated capacity value and initial capacity

The ratio of the values is taken as a battery health degree SOH, and the battery health degree SOH is calculated as:

inputting the battery capacity estimated in the current macro scale step 7) v (2) into the micro time scale in the next macro scale, and updating the battery capacity Cn in the state equation of the battery in the step 5) i for SOC and polarization voltage estimation.

8. The implementation manner of the claim 4 is characterized in that in the step 8), the charging stop time of the charged vehicle simultaneously satisfies two conditions: 1. the charged vehicle is charged with enough electric quantity, and the result of the battery health degree of the charged vehicle is reliable; based on the above two points, the charging stop time determination process is as follows:

when charged to the electric quantity

Set ratio Q to initial capacity of battery _th Time of flight

Considering that condition one is satisfied, step 8) ii is executed at this time, otherwise, the charging is continued, wherein,

the charge quantity accumulated by the ampere-hour integration of the battery

Cn ₀ Is the initial capacity;

and ii, evaluating the reliability of the SOH:

reliability evaluation is performed on the estimated battery health SOH from two evaluation indexes: 1) The increment of mean square error between the terminal voltage measured value and the estimated value is less than the variance increment threshold xi _th ；2)The SOH of the battery obtained by the SOC estimation curve and the ampere-hour cumulant increment and the SOH of the battery obtained by the algorithm estimation are smaller than the SOH change amplitude threshold xi _SOH,th (ii) a And simultaneously satisfying evaluation indexes 1) and 2), the result of the battery health degree SOH is considered to be reliable, and the charging is stopped.

9. The implementation manner as claimed in claim 8, wherein the increment of the mean square error between the terminal voltage measured value and the estimated value on the macroscopic time scale is used as the basic index of the evaluation index 1), and is represented by the following formula:

wherein k =1,2,3 _out,m,k And y _m,k Respectively measuring the terminal voltage actual value and the observed quantity at the microscopic kth moment in the macroscopic mth stage;

when the absolute value of a plurality of continuous macro time scale mean square error increments is smaller than the variance increment threshold xi _th When the method is used:

|ξ _m -ξ _m-1 |＜ξ _th

i =1,2,3.. L, ξ. Are considered to satisfy evaluation index 1), in the formula _m And xi _m-1 Mean square error of terminal voltage of mth and mth-1 macroscopic time scales respectively.

10. The implementation manner of claim 8, wherein the absolute value of the difference of two SOH results at macroscopic time scale is used as the base index of the evaluation index 2), and when the difference of SOH at a plurality of consecutive macroscopic scales is smaller than the threshold value xi of the change amplitude of SOH _SOH,th ：

in the formula, SOC _t And SOC ₀ Respectively the estimated SOC and the initial SOC at the moment;