1. A method for rapidly measuring the electromotive force and the internal resistance of a battery on line is characterized in that: the adopted control circuit comprises a voltage and current measuring unit, a current regulating unit and a control unit; the voltage and current measuring unit is used for measuring the output current value of the target battery and the terminal voltage value of the target battery; the current adjusting unit is used for adjusting working current so as to change the output current of the battery, and the voltage and current measuring unit at one end of the current adjusting unit is electrically connected; the control unit is used for controlling the current regulation unit and the voltage and current measurement unit so as to realize the measurement of the terminal voltage and the output current of the battery and the change of the working current, and is respectively and electrically connected with the voltage and current measurement unit and the current regulation unit; the voltage and current measuring unit is connected with a target battery, and the current regulating unit is connected with a power supply end of target equipment; the control unit establishes communication connection with target equipment; the method comprises the following steps:

s1: the control unit controls the current regulation unit to change the working state of the control circuit or the target equipment so as to regulate the output current of the target battery;

s2: measuring terminal voltage U of target battery by controlling voltage current measuring unit through control unit₁And the current I output by the target battery₁；

S3: repeating the steps S1 and S2 n times to obtain binary arrays (U) of terminal voltage and current in different working states_i，I_i) I is 1,2,3, … …, n, wherein U_iTerminal voltage of target battery measured for I-th time, I_iThe output current of the target battery measured for the ith time;

s4: method for establishing fitting model U of battery terminal voltage-output current by utilizing linear regression method_i＝a*I_i+ b, wherein a and b are model parameters;

s5: determining model parameters a and b by using a least square method;

s6: and estimating the electromotive force EMF and the internal resistance r of the target battery by using the obtained model parameters a and b.

2. The method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to claim 1, wherein the step S5 is specifically as follows:

s51: the sum of the squares of the residuals is calculated as:

wherein Q (a, b) is the sum of the squares of the residuals,. epsilon_iIs the difference between the actual value and the predicted value;

s52: the model parameters a and b are subjected to partial derivatives and made equal to 0, resulting in:

then there are:

s53: thus, the following results are obtained:

wherein:

3. the method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to claim 2, wherein the step S6 is specifically as follows:

s61: the linear regression model of the target battery terminal voltage and the output current is established as follows:

wherein, U is the terminal voltage of the target battery, and I is the output current of the target battery;

s62: the following relationship is provided for the target battery terminal voltage and the target battery output current:

U＝EMF-I*r (7)

wherein EMF is the electromotive force of the target battery, and r is the internal resistance of the target battery;

s63: the target battery electromotive force and the target battery internal resistance can be obtained from the above equations (6) and (7):

4. the method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to claim 3, further comprising:

s7, estimating the SOC of the target battery, wherein the SOC is calculated according to the following formula:

SOC＝f(EMF) (10)

where f (-) is the target battery state of charge-to-electromotive force mapping function.

5. The method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to any one of claims 1 to 4, characterized in that: the current regulation unit consists of n current regulation subunits connected in parallel.

6. The method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to claim 5, characterized in that: each current regulation subunit comprises an MOS tube and a resistor, and the MOS tube in each current regulation subunit is connected with the resistor in series.

7. The method for fast on-line measurement of the electromotive force and the internal resistance of a battery according to claim 1,2,3, 4 or 6, characterized in that: the voltage and current side unit comprises a shunt resistor R and an analog-to-digital conversion circuit, one end of the shunt resistor R is connected with the anode of the target battery and the analog-to-digital conversion circuit respectively, and the other end of the shunt resistor R is connected with the target equipment, the current adjusting unit and the analog-to-digital conversion circuit respectively.

8. The method for rapidly measuring the electromotive force and the internal resistance of the battery on line according to claim 7, characterized in that: said control unit is a general purpose I/O, or I²C. The SPI bus is connected to the target device.

Background

With the continuous advancement of battery technology, there is an increasing use of battery powered devices. The electric automobile can be used as an electric automobile, and the intelligent terminal can be used as an intelligent terminal, so that the electric quantity required by work can be supplied without depending on a battery. In order to effectively utilize the battery and reduce unnecessary resource waste and environmental pollution, accurate evaluation of the state of charge and the health condition of the battery in the operation process is required. The battery electromotive force and the internal resistance are two main parameters for describing the battery charge state and evaluating the battery health condition, and accurate measurement of the battery electromotive force and the internal resistance is crucial to realizing efficient battery management. However, the conventional battery electromotive force and internal resistance measuring device and method either require the establishment of a complicated electrochemical battery model, resulting in that the measuring method can be used only for a specific type of battery and the computational complexity is high; or a complex and expensive professional instrument is needed or the target battery needs to be kept still for a long time, so that the normal operation of the target equipment is interfered, and real-time and quick online measurement cannot be realized. These problems severely limit the effective use of battery management technology, particularly for low-cost, low-power embedded devices.

Therefore, there is a need for a low cost measurement method that can be used with any type of battery, that enables fast online measurements, and that has low requirements on the computing power of the target device.

Disclosure of Invention

The invention aims to provide a method for rapidly measuring the electromotive force and the internal resistance of a battery on line, which can realize rapid on-line measurement and improve the efficiency of measuring the electromotive force and the internal resistance of the battery.

The invention relates to a method for rapidly measuring the electromotive force and the internal resistance of a battery on line, wherein an adopted control circuit comprises a voltage and current measuring unit, a current regulating unit and a control unit; the voltage and current measuring unit is used for measuring the output current value of the target battery and the terminal voltage value of the target battery; the current adjusting unit is used for adjusting working current so as to change the output current of the battery, and the voltage and current measuring unit at one end of the current adjusting unit is electrically connected; the control unit is used for controlling the current regulation unit and the voltage and current measurement unit so as to realize the measurement of the terminal voltage and the output current of the battery and the change of the working current, and is respectively and electrically connected with the voltage and current measurement unit and the current regulation unit; the voltage and current measuring unit is connected with a target battery, and the current regulating unit is connected with a power supply end of target equipment; the control unit establishes communication connection with target equipment; the method comprises the following steps:

s1: the control unit controls the current regulation unit to change the working state of the control circuit or the target equipment so as to regulate the output current of the target battery;

s2: measuring terminal voltage U of target battery by controlling voltage current measuring unit through control unit₁And the current I output by the target battery₁；

S3: repeating the steps S1 and S2 n times to obtain binary arrays (U) of terminal voltage and current in different working states_i，I_i) I is 1,2,3, … …, n, wherein U_iTerminal voltage of target battery measured for I-th time, I_iThe output current of the target battery measured for the ith time;

s4: method for establishing fitting model U of battery terminal voltage-output current by utilizing linear regression method_i＝a*I_i+ b, wherein a and b are model parameters;

s5: determining model parameters a and b by using a least square method;

s6: and estimating the electromotive force EMF and the internal resistance r of the target battery by using the obtained model parameters a and b.

Optionally, the step S5 specifically includes:

s51: the sum of the squares of the residuals is calculated as:

wherein Q (a, b) is the sum of the squares of the residuals,. epsilon_iIs the difference between the actual value and the predicted value;

s52: the model parameters a and b are subjected to partial derivatives and made equal to 0, resulting in:

then there are:

s53: thus, the following results are obtained:

wherein:

optionally, the step S6 specifically includes:

s61: the linear regression model of the target battery terminal voltage and the output current is established as follows:

wherein, U is the terminal voltage of the target battery, and I is the output current of the target battery;

s62: the following relationship is provided for the target battery terminal voltage and the target battery output current:

U＝EMF-I*r (7)

wherein EMF is the electromotive force of the target battery, and r is the internal resistance of the target battery;

s63: the target battery electromotive force and the target battery internal resistance can be obtained from the above equations (6) and (7):

optionally, the method further comprises:

s7, estimating the SOC of the target battery, wherein the SOC is calculated according to the following formula:

SOC＝f(EMF) (10)

where f (-) is the target battery state of charge-to-electromotive force mapping function.

Optionally, the current regulation unit is composed of n parallel current regulation subunits.

Optionally, each of the current adjusting sub-units includes an MOS transistor and a resistor, and the MOS transistor in each of the current adjusting sub-units is connected in series with the resistor.

Optionally, the voltage and current side unit includes a shunt resistor R and an analog-to-digital conversion circuit, one end of the shunt resistor R is connected to the anode of the target battery and the analog-to-digital conversion circuit, and the other end of the shunt resistor R is connected to the target device, the current adjusting unit, and the analog-to-digital conversion circuit.

Optionally, the control unit is a general purpose I/O, or I²C. The SPI bus is connected to the target device.

The invention has the following advantages:

1) the method is suitable for any type of battery, is not limited by the electrochemical components of the battery, and does not need a complex battery model;

2) the method can realize on-line measurement while the target equipment is running, and does not interfere the normal function of the target equipment;

3) the method does not require long-time standing of the target battery, and can realize real-time and quick measurement;

4) the method is simple to implement, has low requirement on the computing capacity of the target equipment, and is particularly suitable for the embedded equipment with low cost and low power consumption.

Drawings

FIG. 1 is a schematic block diagram of the control circuit as an independent module in the present embodiment;

FIG. 2 is a circuit diagram of the control circuit as an independent module in the present embodiment;

FIG. 3 is a schematic block diagram of a portion of the control circuit of the present embodiment integrated on a target device;

FIG. 4 is a schematic block diagram of the present embodiment in which all control circuits are integrated into the target device;

FIG. 5 is a flowchart of the present embodiment;

fig. 6 is a graph for testing the relationship between the EMF corresponding to different SOCs of the alkaline battery.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

In the embodiment, a method for rapidly measuring the electromotive force and the internal resistance of a battery on line adopts a control circuit which comprises a voltage and current measuring unit, a current regulating unit and a control unit; the voltage and current measuring unit is used for measuring the output current value of the target battery and the terminal voltage value of the target battery; the current adjusting unit is used for adjusting working current so as to change the output current of the battery, and the voltage and current measuring unit at one end of the current adjusting unit is electrically connected; the control unit is used for controlling the current regulation unit and the voltage and current measurement unit so as to realize the measurement of the terminal voltage and the output current of the battery and the change of the working current, and the control unit is respectively and electrically connected with the voltage and current measurement unit and the current regulation unit. The voltage and current measuring unit is connected with a target battery, and the current regulating unit is connected with a power supply end of target equipment; the control unit establishes communication connection with the target device.

In this embodiment, a method for rapidly measuring the electromotive force and the internal resistance of a battery on line includes the following steps:

s1: the control unit controls the current regulation unit to change the working state of the control circuit or the target equipment so as to regulate the output current of the target battery;

s2: measuring terminal voltage U of target battery by controlling voltage current measuring unit through control unit₁And the current I output by the target battery₁；

S3: repeatedly executing step S1 and step n timesS2, obtaining a binary array (U) of terminal voltage and current under different working states_i，I_i) I is 1,2,3, … …, n, wherein U_iTerminal voltage of target battery measured for I-th time, I_iThe output current of the target battery measured for the ith time;

s4: method for establishing fitting model U of battery terminal voltage-output current by utilizing linear regression method_i＝a*I_i+ b, wherein a and b are model parameters;

s5: determining model parameters a and b by using a least square method;

s6: and estimating the electromotive force EMF and the internal resistance r of the target battery by using the obtained model parameters a and b.

The method can estimate the electromotive force and the internal resistance of the battery through simple linear model fitting by changing the working state and measuring the terminal voltage and the output current of the battery, thereby having extremely low complexity and calculation expense. The method is suitable for any type of battery, can realize quick online measurement while the target equipment operates, and greatly improves the efficiency of measuring the electromotive force and the internal resistance of the battery.

In this embodiment, the step S5 specifically includes:

s51: the sum of the squares of the residuals is calculated as:

wherein Q (a, b) is the sum of the squares of the residuals,. epsilon_iIs the difference between the actual value and the predicted value;

s52: the model parameters a and b are subjected to partial derivatives and made equal to 0, resulting in:

then there are:

s53: thus, the following results are obtained:

wherein:

in this embodiment, the step S6 specifically includes:

s61: the linear regression model of the target battery terminal voltage and the output current is established as follows:

wherein, U is the terminal voltage of the target battery, and I is the output current of the target battery;

s62: the following relationship is provided for the target battery terminal voltage and the target battery output current:

U＝EMF-I*r (7)

wherein E is the electromotive force of the target battery, and r is the internal resistance of the target battery;

s63: the target battery electromotive force and the target battery internal resistance can be obtained from the above equations (6) and (7):

in this embodiment, the method further includes:

s7, estimating the SOC of the target battery, wherein the SOC is calculated according to the following formula:

SOC＝f(EMF) (10)

wherein: f (-) is the target battery state of charge-electromotive force mapping function.

In this embodiment, the control signal is general purpose I/O, or I²C. The SPI bus is connected to the target device.

In this embodiment, the control circuit may be an independent module (as shown in fig. 1 and fig. 2), or a part of the control circuit may be integrated on the target device (see fig. 3) or all the control circuit may be integrated on the target device (see fig. 4).

As shown in fig. 1 and fig. 2, the following description will be made by taking an example in which the control circuit is an independent module:

the voltage and current measuring unit is composed of an analog-to-digital converter and a shunt resistor R, one end of the shunt resistor R is connected with the anode of the target battery and the analog-to-digital conversion circuit respectively, and the other end of the shunt resistor R is connected with the target equipment, the current adjusting unit and the analog-to-digital conversion circuit respectively. By measuring the terminal voltages Vin and Vout of the shunt resistor R, the terminal voltage and the output current of the target battery can be obtained.

The current regulation unit consists of n current regulation subunits connected in parallel. Each current regulation subunit comprises an MOS tube and a resistor, and the MOS tube in each current regulation subunit is connected with the resistor in series. The equivalent load resistance of the circuit is changed by controlling the conduction of the MOS tube, so that the aim of changing the output current of the target battery is fulfilled.

As shown in fig. 2 and fig. 5, the control part in this example may be implemented by the control unit, or may be implemented by software of the target device, and specifically includes the following steps:

s1: the grid voltage of the MOS tube 1 is controlled by the control unit, so that the MOS tube 1 is conducted, and the rest MOS tubes are cut off;

s2: measuring the voltage U of the target battery terminal at the moment through an analog-to-digital conversion circuit₁(ii) a The voltage of the R end of the shunt resistor is measured through an analog-to-digital conversion circuit, and the output current I of the battery at the moment is further measured₁；

S3: repeating the above steps S1 and S2 to turn on different MOS transistors to obtain binary arrays (U) of terminal voltage and output current of n groups of batteries in different working states_i，I_i)；

S4: establishing a fitting model U of the battery terminal voltage-output current by using a linear regression method_i＝a*I_i+b；

S5: determining relevant parameters in the linear regression model by using a least square method;

s6: and estimating the electromotive force E and the internal resistance r of the target battery by using the obtained model parameters.

In the present embodiment, the kind of the target battery is not limited, and any battery such as a commonly used lithium battery, alkaline battery, and lithium secondary battery may be used. The target device is also not limited and may be various battery-powered devices.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.