A battery charging control method and system

Abstract

This invention discloses a battery charging control method, comprising the following steps: when the minimum temperature of a single battery cell is less than a predetermined threshold A℃, a motor outputs current to a heating wire to heat the battery without charging it; if the BMS detects that the battery has a charging current, the motor output current is reduced; if the BMS detects that the battery's discharge current to the heating wire is greater than a predetermined threshold, the motor output current to the heating wire is increased. This invention detects the presence of charging current in the battery during low-temperature charging and heating, preventing the motor from charging the battery at low temperatures and affecting its lifespan, thereby extending the battery's service life; and detects whether the battery's discharge current exceeds a set threshold during low-temperature charging and heating, and adaptively adjusts the motor output current accordingly, preventing excessive discharge current and rapid capacity loss at low temperatures, thus extending the battery's usable time.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging technology, and more specifically to a battery charging control method and system. Background Technology

[0002] With the increasing use of new energy electric vehicles, most of which use lithium batteries as their power source, the capacity and discharge rate of lithium batteries decrease significantly in low-temperature environments (capacity reduction means the battery cannot release enough electricity at low temperatures, and discharge rate reduction means the maximum discharge current decreases at low temperatures). Therefore, a heating scheme needs to be added to the lithium battery. When the lithium battery is in a low-temperature environment, it can be heated to keep the battery within its optimal operating temperature range. There are various heating schemes, but the most common one currently used is electric heating wire heating (the heating wire is connected in parallel with the battery). During discharge, if heating is turned on, the current of the heating wire is determined by the battery voltage. When heating is needed for charging, the heating current is provided by the motor. The general practice is to request a current from the motor equal to the battery's allowable charging current, plus the fixed heating current of the heating wire.

[0003] The shortcoming of the existing technology is that when the battery's allowed charging current is A (i.e., charging is not allowed), the current output by the motor is a fixed heating current value. When the voltage across the heating wire is different, the current flowing through the resistance wire is different. This fixed current may be greater than or less than the current flowing through the heating wire. When it is greater than the current flowing through the heating wire, the current will flow into the battery connected in parallel with the heating wire. When it is less than the current flowing through the heating wire, the battery connected in parallel with the heating wire will discharge to the heating wire, generating a discharge current. Summary of the Invention

[0004] The purpose of this invention is to address the following issues during battery heating: if battery discharge occurs (the battery discharges to the heating wire), it will reduce the available battery power and decrease the driving range; if the battery is charged or the charging current is too large (the heating wire cannot consume much current and will charge the battery), it will affect the battery's lifespan. The invention provides a battery charging control method and system.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A battery charging control method, the method comprising the following steps:

[0007] When the minimum temperature of a single battery cell is less than a predetermined threshold A℃, the motor outputs current to the heating wire to heat the battery without charging it.

[0008] If the BMS detects that the battery has a charging current, it will reduce the current output by the motor until the battery has no charging current. This is to prevent the current output by the motor to the heating wire from being too large at low temperatures, which would cause some of the current in the heating wire to flow to the battery and cause improper charging of the battery, affecting the battery's lifespan and thus extending the battery's service life.

[0009] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold, it increases the current output by the motor to the heating wire until the discharge current of the battery is less than the predetermined threshold. When the current supplied by the motor to the heating wire is insufficient, the battery will discharge to the heating wire. Therefore, increasing the current output by the motor at this time avoids excessive discharge current of the battery, rapid depletion of battery power, and extends battery life.

[0010] As a preferred embodiment of the present invention, the method specifically includes the following steps:

[0011] Detect the battery temperature and determine whether the minimum temperature of a single battery cell, T_min, is less than A℃. If T_min < A℃;

[0012] The battery is heated by a heating wire, and the motor output current is requested according to the power of the heating wire, wherein the output current is equal to the rated current of the heating wire.

[0013] If the BMS detects that the battery is charging current, it will reduce the current output by the motor. The value of the current output by the motor will be reduced by a set threshold αA each time until the heating wire no longer provides charging current to the battery.

[0014] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold βA, it will increase the current output by the motor to the heating wire by a set threshold αA each time until the discharge current of the battery is less than βA; where α < β.

[0015] As a preferred embodiment of the present invention, the method further includes the following steps:

[0016] The temperature of a single battery cell is measured, including T_min and T_max. If A℃≤T_min<B℃ and T_max<C℃, where T_max represents the maximum battery temperature and A<B<C; the battery is charged and heated simultaneously using a heating wire and a motor, and the motor output current is requested; the output current = Min((MAP meter)*SOH+ heating wire rated current);

[0017] If T_min≥B℃ or T_max>C℃, the battery is charged only by the motor, and the output current of the motor charges the battery. The output current = Min((MAP table)*SOH);

[0018] The MAP table is a MAP table showing the battery's chargeability at different voltages and temperatures, and the SOH is the battery health status.

[0019] By heating the battery at low temperatures, charging and heating the battery simultaneously when the battery temperature reaches a suitable operating range, and charging the battery only when the battery temperature is too high, the system avoids charging the battery at low temperatures and prevents potential damage to the battery in high-temperature environments. This also avoids a significant reduction in battery capacity and discharge rate in low-temperature environments, thereby improving battery efficiency.

[0020] As a preferred embodiment of the present invention, the method further includes the following steps: determining the maximum voltage V1max of a single battery cell; if V1max ≥ M, then ending the current charging, where M is the maximum allowable charging voltage value for a single battery cell.

[0021] In a preferred embodiment of the present invention, A = 0, B = 15, and C = 25.

[0022] As a preferred embodiment of the present invention, the voltage output by the motor is V2max, where V2max>V1max. The motor voltage must be greater than the battery voltage in order to charge the battery. Preferably, V2max = V1max + 5V.

[0023] In a preferred embodiment of the present invention, α = 1 and β = 2.

[0024] As a preferred embodiment of the present invention, the temperature of the battery cell is detected by a BMS.

[0025] The present invention also provides a battery charging control system, the system being capable of performing any of the methods described above, including a line impedance R1, a heating wire R2, a battery internal resistance r, a current sampling resistor, a motor, and a battery;

[0026] The battery includes a positive electrode and a negative electrode.

[0027] The positive terminal of the battery is electrically connected to one end of the heating wire R2 and one end of the line impedance R1 through the battery internal resistance r.

[0028] The other end of the line impedance R1 is electrically connected to one end of the motor, and the other end of the motor is electrically connected to the negative terminal of the battery through a current sampling resistor;

[0029] The other end of the heating wire R2 is electrically connected to the negative terminal of the battery through a current sampling resistor.

[0030] As a preferred embodiment of the present invention, the heating wire R2 has a rated current of 10A.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. This invention detects whether there is charging current in the battery when it is being charged and heated at low temperatures, thus preventing the motor from charging the battery at low temperatures and affecting its lifespan, thereby extending the battery's service life.

[0033] 2. This invention detects whether the battery discharge current exceeds a predetermined threshold when the battery is being charged and heated at low temperatures, and adaptively adjusts the motor output current to avoid excessive discharge current and rapid power loss at low temperatures, thereby extending the battery's usable time.

[0034] 3. This invention heats the battery at low temperatures, and simultaneously charges and heats the battery when the temperature reaches a suitable operating range. When the battery temperature is too high, it only charges the battery. This avoids charging the battery at low temperatures and prevents damage to the battery in high-temperature environments. It also avoids a significant reduction in battery capacity and discharge rate in low-temperature environments, thereby improving battery efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the workflow of a battery charging control method according to the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of a vehicle charging and heating module according to the present invention. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0038] Example 1

[0039] Please refer to the attached document. Figure 1 As shown, this embodiment provides a battery charging control method, which includes the following steps:

[0040] When the minimum temperature of a single battery cell is less than a predetermined threshold of 0°C, the motor outputs current to the heating wire to heat the battery without charging it.

[0041] If the BMS detects that the battery has a charging current, it will reduce the current output by the motor until the battery has no charging current. This is to prevent the current output by the motor to the heating wire from being too large at low temperatures, which would cause some of the current in the heating wire to flow to the battery and cause improper charging of the battery, affecting the battery's lifespan and thus extending the battery's service life.

[0042] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold, it increases the current output by the motor to the heating wire until the discharge current of the battery is less than the predetermined threshold. When the current supplied by the motor to the heating wire is insufficient, the battery will discharge to the heating wire. Therefore, increasing the current output by the motor at this time avoids excessive discharge current of the battery, rapid depletion of battery power, and extends battery life.

[0043] Example 2

[0044] Please refer to the attached document. Figure 1 As shown, this embodiment is a further optimization and improvement based on embodiment 1, specifically including the following steps:

[0045] Detect the battery temperature and determine whether the minimum temperature of a single battery cell, T_min, is less than 0℃. If T_min < 0℃;

[0046] The battery is heated by a heating wire, and the motor output current is requested according to the power of the heating wire, wherein the output current is equal to the rated current of the heating wire.

[0047] If the BMS detects that the battery is charging current, it will reduce the current output by the motor. The current output by the motor will be reduced by a set threshold of 1A each time until the heating wire no longer provides charging current to the battery.

[0048] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold of 2A, it will increase the current output by the motor to the heating wire by a set threshold of 1A each time until the discharge current of the battery is less than 2A.

[0049] The method further includes the following steps:

[0050] The temperature of a single battery cell is detected by measuring T_min and T_max. If 0℃≤T_min<15℃ and T_max<25℃, the battery is charged and heated simultaneously using a heating wire and a motor. The motor output current is requested, and the output current is Min((MAP meter)*SOH+heating wire rated current), where T_max represents the maximum battery temperature.

[0051] If T_min≥15℃ or T_max>25℃, the battery is charged only by the motor, and the output current of the motor charges the battery, the output current = Min((MAP table)*SOH);

[0052] The MAP table is a MAP table showing the battery's chargeability at different voltages and temperatures, and the SOH is the battery health status.

[0053] By heating the battery at low temperatures, charging and heating the battery simultaneously when the battery temperature reaches a suitable operating range, and charging the battery only when the battery temperature is too high, the system avoids charging the battery at low temperatures and prevents potential damage to the battery in high-temperature environments. This also avoids a significant reduction in battery capacity and discharge rate in low-temperature environments, thereby improving battery efficiency.

[0054] The method further includes the following steps: determining the maximum voltage V1max of a single battery cell; if V1max ≥ M, then ending the current charging, where M is the maximum allowable charging voltage value for a single battery cell.

[0055] The voltage output by the motor is V2max, where V2max > V1max. The motor voltage must be greater than the battery voltage to charge the battery. Preferably, V2max = V1max + 5V.

[0056] The temperature of the battery cells is detected by the BMS.

[0057] Example 3

[0058] Please refer to the attached document as well. Figure 1 With appendix Figure 2 As shown, this embodiment provides a battery charging control method, which includes the following steps:

[0059] When the minimum temperature of a single battery cell is less than a predetermined threshold of 3°C, the motor outputs current to the heating wire to heat the battery without charging it.

[0060] If the BMS detects that the battery has a charging current, it will reduce the current output by the motor until the battery has no charging current. This is to prevent the current output by the motor to the heating wire from being too large at low temperatures, which would cause some of the current in the heating wire to flow to the battery and cause improper charging of the battery, affecting the battery's lifespan and thus extending the battery's service life.

[0061] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold, it increases the current output by the motor to the heating wire until the discharge current of the battery is less than the predetermined threshold. When the current supplied by the motor to the heating wire is insufficient, the battery will discharge to the heating wire. Therefore, increasing the current output by the motor at this time avoids excessive discharge current of the battery, rapid depletion of battery power, and extends battery life.

[0062] The method specifically includes the following steps:

[0063] Detect the battery temperature and determine whether the minimum temperature of a single battery cell, T_min, is less than 3℃. If T_min < 3℃;

[0064] The battery is heated by a heating wire, and the motor output current is requested according to the power of the heating wire, wherein the output current is equal to the rated current of the heating wire.

[0065] If the BMS detects that the battery is charging current, it will reduce the current output by the motor. The current output by the motor will be reduced by a set threshold of 0.5A each time until the heating wire no longer provides charging current to the battery.

[0066] If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold of 3A, it will increase the current output by the motor to the heating wire by a set threshold of 0.5A each time until the discharge current of the battery is less than 3A.

[0067] The method further includes the following steps:

[0068] The temperature of a single battery cell is detected by measuring T_min and T_max. If 3℃≤T_min<18℃ and T_max<28℃, the battery is charged and heated simultaneously using a heating wire and a motor. The motor output current is requested, and the output current is Min((MAP meter)*SOH+heating wire rated current), where T_max represents the maximum battery temperature.

[0069] If T_min≥18℃ or T_max>28℃, the battery is charged only by the motor. The output current of the motor charges the battery, and the output current = Min((MAP table)*SOH);

[0070] The MAP table is a MAP table showing the battery's chargeability at different voltages and temperatures, and the SOH is the battery health status.

[0071] By heating the battery at low temperatures, charging and heating the battery simultaneously when the battery temperature reaches a suitable operating range, and charging the battery only when the battery temperature is too high, the system avoids charging the battery at low temperatures and prevents potential damage to the battery in high-temperature environments. This also avoids a significant reduction in battery capacity and discharge rate in low-temperature environments, thereby improving battery efficiency.

[0072] The method further includes the following steps: determining the maximum voltage V1max of a single battery cell; if V1max ≥ M, then ending the current charging, where M is the maximum allowable charging voltage value for a single battery cell.

[0073] The voltage output by the motor is V2max, where V2max > V1max. The motor voltage must be greater than the battery voltage in order to charge the battery. Preferably, V2max = V1max + 5V.

[0074] The temperature of the battery cells is detected by the BMS.

[0075] Please refer to the attached document. Figure 2 As shown, this embodiment also provides a battery charging control system, which is capable of executing any of the methods described above, including line impedance R1, heating wire R2, battery internal resistance r, current sampling resistor, motor and battery;

[0076] The battery includes a positive electrode and a negative electrode.

[0077] The positive terminal of the battery is electrically connected to one end of the heating wire R2 and one end of the line impedance R1 through the battery internal resistance r.

[0078] The other end of the line impedance R1 is electrically connected to one end of the motor, and the other end of the motor is electrically connected to the negative terminal of the battery through a current sampling resistor;

[0079] The other end of the heating wire R2 is electrically connected to the negative terminal of the battery through a current sampling resistor.

[0080] The heating wire R2 has a rated current of 10A.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery charging control method, characterized in that, The charging control method is applied to a battery charging control system, which includes a line impedance R1, a heating wire R2, a battery internal resistance r, a current sampling resistor, a motor, and a battery. The battery includes a positive terminal and a negative terminal. The positive terminal is electrically connected to one end of the heating wire R2 and one end of the line impedance R1 through the battery internal resistance r. The other end of the line impedance R1 is electrically connected to one end of the motor, and the other end of the motor is electrically connected to the negative terminal of the battery through the current sampling resistor. The other end of the heating wire R2 is electrically connected to the negative terminal of the battery through the current sampling resistor. The method comprises the following steps: When the minimum temperature of a single battery cell is less than a predetermined threshold A℃, the motor outputs current to the heating wire to heat the battery without charging it. If the BMS detects that the battery has charging current, it will reduce the current output by the motor until the battery has no charging current. If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold, it will increase the current output by the motor to the heating wire until the discharge current of the battery is less than the predetermined threshold. The method specifically includes the following steps: Detect the battery temperature and determine whether the minimum temperature of a single battery cell, T_min, is less than A℃. If T_min < A℃; The battery is heated by a heating wire, and the motor output current is requested according to the power of the heating wire, wherein the output current is equal to the rated current of the heating wire. If the BMS detects that the battery is charging current, it will reduce the current output by the motor. The value of the current output by the motor will be reduced by a set threshold αA each time until the heating wire no longer provides charging current to the battery. If the BMS detects that the discharge current of the battery to the heating wire is greater than a predetermined threshold βA, it will increase the current output by the motor to the heating wire by a set threshold αA each time until the discharge current of the battery is less than βA; where α < β.

2. The battery charging control method according to claim 1, characterized in that, The method further includes the following steps: The temperature of a single battery cell is measured, including T_min and T_max. If A℃≤T_min<B℃ and T_max<C℃, where T_max represents the maximum battery temperature and A<B<C; the battery is charged and heated simultaneously using a heating wire and a motor, and the motor output current is requested; the output current = Min((MAP meter)*SOH+ heating wire rated current); If T_min≥B℃ or T_max>C℃, the battery is charged only by the motor, and the output current of the motor charges the battery. The output current = Min((MAP table)*SOH); The MAP table is a MAP table showing the battery's chargeability at different voltages and temperatures, and the SOH is the battery health status.

3. A battery charging control method according to any one of claims 1 to 2, characterized in that, The method further includes the following steps: The highest voltage V1max of a single battery cell is determined. If V1max ≥ M, the current charging is terminated, where M is the highest allowable charging voltage value for a single battery cell.

4. The battery charging control method according to claim 2, characterized in that, Where A = 0, B = 15, and C = 25.

5. The battery charging control method according to claim 3, characterized in that, The voltage output by the motor is V2max, where V2max > V1max.

6. The battery charging control method according to claim 1, characterized in that, α = 1, β = 2.

7. The battery charging control method according to claim 1, characterized in that, The temperature of the battery cells is detected by the BMS.

8. A battery charging control system, characterized in that, The system is capable of executing the method of any one of claims 1 to 7, comprising a line impedance R1, a heating wire R2, a battery internal resistance r, a current sampling resistor, a motor, and a battery; the battery comprises a positive terminal and a negative terminal; the positive terminal of the battery is electrically connected to one end of the heating wire R2 and one end of the line impedance R1 through the battery internal resistance r; the other end of the line impedance R1 is electrically connected to one end of the motor, and the other end of the motor is electrically connected to the negative terminal of the battery through the current sampling resistor; the other end of the heating wire R2 is electrically connected to the negative terminal of the battery through the current sampling resistor.

9. A battery charging control system according to claim 8, characterized in that, The heating wire R2 has a rated current of 10A.

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