Battery heating method for electric two / three-wheelers

Abstract

The application relates to a battery heating method for an electric two / three-wheeled vehicle, which comprises the following steps: S1, detecting the battery temperature, if the battery temperature is normal, the charger normally charges the battery; if the battery temperature is low, the next step is performed; S2, detecting the remaining battery capacity, corresponding operations are performed according to different situations of the remaining battery capacity until the battery temperature reaches a preset value; and S3, the charger normally charges the battery. The application can rapidly increase the battery temperature by using the charger, the motor and the electric control on the vehicle without increasing the hardware cost; when the battery temperature is increased to a proper temperature, the charger can directly charge at a large rate, the charging power does not need to be limited due to the low temperature, and even the battery can be charged, so that the charging time can be greatly reduced; in a low-temperature environment, the battery capacity loss is large, the application can greatly improve the battery capacity in the low-temperature environment, and the cruising range during travel is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric two-wheelers and three-wheelers, and in particular to a battery heating method for electric two-wheelers and three-wheelers. BACKGROUND

[0002] At present, power batteries have good applications in electric vehicles or electric two-wheelers and three-wheelers. However, power batteries are easily affected by temperature, which in turn affects the normal use of vehicles and the experience of customers.

[0003] Therefore, the power battery heating method is usually used to solve this problem. However, the methods mentioned in the prior art, such as the published patents CN 111572408 A, CN 112448640 A, CN 104538701 A and the published literature “Journal of Power Supply Based on Electric Drive Inverter Reconstruction of Vehicle Power Lithium Battery Self-heating Strategy”, are effective for electric vehicles, but have deficiencies for electric two-wheelers and three-wheelers. This is because:

[0004] Suppose the equivalent internal resistance of the battery is R 电池 , and the sum of all equivalent resistances outside the battery is R 外部 .

[0005] If the battery self-generated energy is used for heating, the heating efficiency is: From this formula, it can be seen that the greater the external resistance of the battery, the lower the heating efficiency, and the greater the internal resistance of the battery, the higher the heating efficiency.

[0006] The power loop characteristics of electric vehicles are: the battery voltage is high, generally several hundred volts, the capacitance is large (generally tens of degrees to dozens of degrees), the battery capacity is large, but because the voltage is high, the battery is connected in series, so the overall internal resistance of the battery does not decrease too much, while the internal resistance of the wire outside the battery, the internal resistance of the electric control, and the internal resistance of the motor are relatively low. The overall battery internal resistance and external resistance ratio is high, the heating efficiency is high, and the battery capacity is large, which meets the self-heating condition.

[0007] The power loop characteristics of electric two-wheelers and three-wheelers are: the battery voltage is low, generally not more than 72V, the battery capacity is small (generally from zero point several degrees to 2 degrees), the battery is connected in series, and the battery internal resistance is small. While the internal resistance of the wire outside the battery, the internal resistance of the electric control, and the internal resistance of the motor are relatively high. The overall battery internal resistance and external resistance ratio is low, the heating efficiency is low, and the battery capacity is small. Even if self-heating can be performed, the battery energy loss ratio is large, the use scenario is limited, and it is not practical.

[0008] Moreover, the above method is not applicable when the battery SOC (battery remaining capacity) is insufficient. SUMMARY

[0009] The technical problem solved by the present application is to provide a battery heating method for electric two / three-wheelers, which has practicality without increasing hardware cost.

[0010] The technical solution adopted by the present application to solve the technical problem is a battery heating method for electric two / three-wheelers, comprising the following steps,

[0011] S1, detecting the battery temperature, if the battery temperature is normal, the charger normally charges the battery; if the battery temperature is lower than the normal temperature, the next step is performed;

[0012] S2, detecting the remaining battery capacity, and performing corresponding operations according to different situations of the remaining battery capacity until the battery temperature reaches a preset value;

[0013] S3, the charger normally charges the battery.

[0014] Further, in the step S2 of the present application, the different situations of the remaining battery capacity include three situations of high, moderate and low remaining battery capacity.

[0015] Further, in the step S2 of the present application, when the remaining battery capacity is high, the following steps are included,

[0016] S21, reading the motor position information;

[0017] S22, performing AC charging and discharging of the battery through the electric control and the motor, and opening the corresponding switch tube in the electric control through the motor position information until the battery temperature reaches the preset value.

[0018] Further, in the step S2 of the present application, when the remaining battery capacity is moderate, the following steps are included,

[0019] S21', reading the motor position information;

[0020] S22', performing AC charging and discharging of the battery through the electric control and the motor, and opening the corresponding switch tube in the electric control through the motor position information, while the charger performs supplementary charging of the battery until the battery temperature reaches the preset value.

[0021] Further, in the step S2 of the present application, when the remaining battery capacity is low, the following steps are included,

[0022] S21'', the charger trickle charges the battery;

[0023] S22'', reading the motor position information;

[0024] S23”, the battery is charged and discharged with AC power through the electronic control and the motor, and the corresponding switch tube in the electronic control is opened according to the motor position information. At the same time, the charger supplements the battery until the battery temperature reaches the preset value.

[0025] Furthermore, in step S23″ of the present invention, the charger performing supplementary charging on the battery means replenishing the energy lost by the battery during the battery heating process.

[0026] Furthermore, the electronic control described in the present invention and the battery exchange information on battery identity, battery temperature and remaining battery power through communication means; the motor is directly connected to the electronic control; and the electronic control reads the magnetic field position information of the motor's stator and rotor through a position sensor installed in the motor.

[0027] The beneficial effect of the present invention is that it solves the defects existing in the background technology without increasing the hardware cost. Only the charger is used, combined with the motor and electronic control on the whole vehicle, to quickly raise the battery temperature. When the battery temperature is raised to a suitable temperature, the charger can directly charge at a larger rate. There is no need to limit the charging power due to low temperature, or even to be unable to charge, which can greatly reduce the charging time. In a low-temperature environment, the battery capacity loss is large. The present invention can greatly increase the battery capacity in a low-temperature environment and ensure the cruising range during travel. For lithium batteries that are not resistant to low temperatures, the probability of lithium plating can be greatly reduced, which is very beneficial for extending the battery life. Reducing the probability of lithium dendrite growth can also reduce the probability of puncturing the internal diaphragm of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic flow chart of the method of the present invention;

[0029] Figure 2 This is a schematic diagram of the battery heating circuit of the present invention;

[0030] Figure 3 This is the equivalent circuit diagram of the battery discharge of the present invention;

[0031] Figure 4 It is the battery charging equivalent circuit diagram of the present invention. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0033] like Figures 1-4 The battery heating method of an electric two-wheeled vehicle shown in the figure comprises the following steps:

[0034] S1, detect the battery temperature, if the battery temperature is normal, the charger charges the battery normally; if the battery temperature is low, the next step is performed;

[0035] S2, detect the battery remaining power, and perform corresponding operations according to different situations of the battery remaining power until the battery temperature reaches the preset value;

[0036] When the battery remaining power is high, the motor position information is read first; then the battery is charged and discharged by alternating current through the electric control and the motor, and the corresponding switch tube in the electric control is opened through the motor position information until the battery temperature reaches the preset value;

[0037] When the battery remaining power is moderate, the motor position information is read first; then the battery is charged and discharged by alternating current through the electric control and the motor, and the corresponding switch tube in the electric control is opened through the motor position information, while the charger supplements the charging of the battery until the battery temperature reaches the preset value;

[0038] When the battery remaining power is low, the battery is trickle charged by the charger first; then the motor position information is read; then the battery is charged and discharged by alternating current through the electric control and the motor, and the corresponding switch tube in the electric control is opened through the motor position information, while the charger supplements the charging of the battery until the battery temperature reaches the preset value;

[0039] S3, the charger charges the battery normally.

[0040] The working principle is described in detail as follows.

[0041] The basic circuit framework is shown in Figure 2 The core devices include the charger, the battery, the electric control, and the motor. The electric control and the battery exchange information through communication means, including battery identification, battery temperature, and SOC. The motor is directly connected to the electric control, and the electric control can read the motor magnetic field position information through the Hall or encoder installed in the motor.

[0042] When the vehicle is shipped, the battery resistance, motor resistance, electric control resistance, and wire resistance are fixed. After a long time of use, except that the battery resistance increases, the other parameters remain almost unchanged. The increase of the battery resistance only increases the heating efficiency for this method, which is a beneficial change for this method.

[0043] Let the difference between the current battery temperature and the target temperature be ΔT,

[0044] The mass of the battery is m,

[0045] The specific heat capacity of the battery is c,

[0046] The current of the entire circuit is i,

[0047] The whole heating process time is t,

[0048] Since the battery itself is a closed environment, for the convenience of calculation, the error caused by battery heat dissipation is not considered in this method, and in actual engineering application, it can be compensated by simulation, debugging and other means.

[0049] The energy required to reach the expected temperature of the battery: w 电池 = c * m * ΔT = i 2 R 电池 t,

[0050] External internal total resistance synchronous loss energy:

[0051] The total energy required by the battery w 总 = w 电池 + w 外部 ,

[0052] That is, to reach the energy required for the expected temperature of the battery, it needs to meet w SOC + w 充 > w 总 , Note that w 充 here is not trickle charging energy, but the maximum synchronous charging energy allowed by the battery under the current battery temperature condition. If w 充 + w SOC < w 总 , trickle charging is required before battery heating, and when w 涓流 + w 充 + w SOC > w 总 condition, battery heating can be performed.

[0053] Before heating work, the motor rotor position must be determined. If an absolute encoder is used, the rotor angle can be accurately known, and the duty cycle of the switching tube is adjusted to make the angle between the stator magnetic field and the rotor magnetic field 0°, avoiding the generation of electromagnetic torque; If the Hall form is used to know the rotor angle, since the Hall has only 6 states, each state is in a m*60°±30° sector, where m=0, 1, 2, 3, 4, 5, in this sector, the system cannot get accurate angle, the maximum angle between stator and rotor magnetic field is ±30°, the maximum mechanical angle that the wheel can rotate is: Where n is the number of motor pole pairs, and the displacement distance that this mechanical angle can produce on the whole vehicle is Where d is the tire outer diameter of the drive wheel; for example, the tire outer radius of a certain national standard electric bicycle motor drive wheel is about 0.4 m, the motor pole pair number is 23 pole pairs, and the above formula is entered, so the maximum displacement distance of the whole vehicle is about ±5 mm, that is, 5 mm forward or backward, and if the vehicle is parked for charging at this time, the moving distance does not affect the parking safety at all.

[0054] After the rotor angle is determined, the power tube needs to be opened to charge and discharge the battery. If the current rotor angle is in a certain sector, in order to make the angle between the stator and rotor magnetic fields ≤±30, the 1, 6, and 2 switch tubes need to be opened. The equivalent circuit and current direction after opening are shown in Figure 3 Figure 3 The arrow direction in the middle is the current flow direction.

[0055] Here, the current carrying capacity of the entire loop needs to be considered. Since the battery is in an alternating charge and discharge state, the charge and discharge rate is very high, and under normal circumstances, the battery current capacity problem can be ignored, and at this time the charger can also assist to supplement part of the current according to the situation, such as Figure 3 The current direction of the charger, the input current at Vcc is provided by the battery and the charger together. The motor and the wire are relatively low in temperature at that time, and the conductor itself can withstand a relatively large instantaneous current capacity. Only the switch tube inside the electronic control is a semiconductor device, which is the bottleneck of the current capacity of the entire loop. At this time, assuming that the maximum peak current that the electronic control can withstand is i max , when the peak value of the bus current detected by the current detection module inside the electronic control reaches i max , the 1, 6, and 2 switches need to be closed, and after a certain dead time, the 3, 4, and 5 switches are opened (in the dead time, the electric energy can be assisted by the diode inside the switch tube to conduct), and the equivalent circuit is shown in Figure 4 Figure 4 The arrow direction in the middle is the current flow direction.

[0056] Due to loop loss problems, the battery cannot discharge 100% to the inductor, and the magnetic energy in the inductor cannot be 100% returned to the battery. In a charge and discharge cycle,

[0057] w 电池放电 = w 电感储能 + w 电池放电时回路总内阻损耗 ,

[0058] w 电池充电 = w 电感储能 - w 电池充电时回路总内阻损耗 ,

[0059] The energy lost by the battery between charging and discharging is:

[0060] w 损失 = w 电池放电 ​​-w 电池充电 = w 电池放电时总内阻损耗 + w 电池充电时总内阻损耗 ,

[0061] The charger at this time to do is to charge and discharge of the battery to supplement some back w 损失 The energy, try to make the battery charge and discharge to balance, reduce the loss of battery remaining power.

[0062] The difference between the charger to supplement the charge and normal charging: normal charging refers to the normal charging process according to the battery SOC, until the battery is full, the process has constant current, constant voltage, trickle current, etc., the whole process is not always full power charging, is a direct power for the battery. And supplement the charge, its purpose is not to directly increase the battery power, but in the process of battery heating will lose energy, these losses will make the battery SOC is getting lower and lower, the charger is to charge the lost energy, is directly consumed in the loop total internal resistance, the whole output process power is basically full power output state.

[0063] The above description is only the specific embodiments of the present application, various examples do not constitute a limitation on the essential content of the present application, those skilled in the art can modify or deform the previous described specific embodiments after reading the specification, without departing from the essence and scope of the invention.

Claims

1. A method for heating a battery of an electric two- or three-wheeled vehicle, characterized in that: The following steps are included: S1. Detect the battery temperature. If the battery temperature is normal, the charger charges the battery normally. If the battery temperature is lower than normal, proceed to the next step. S2. Detect the remaining battery power and perform corresponding operations according to the remaining battery power until the battery temperature reaches a preset value; S3, the charger charges the battery normally; In step S2, the different situations of the remaining battery power include three situations: high remaining battery power, moderate remaining battery power, and low remaining battery power; In the step S2, when the remaining battery power is high, the following steps are included: S21, read the motor position information; S22, charging and discharging the battery with AC power through the electronic control and motor, and turning on the corresponding switch in the electronic control according to the motor position information until the battery temperature reaches a preset value; In the step S2, when the remaining battery power is moderate, the following steps are included: S21', read the motor position information; S22', charging and discharging the battery with AC power through the electronic control and the motor, and turning on the corresponding switch in the electronic control according to the motor position information, while the charger supplements the battery until the battery temperature reaches a preset value; In the step S2, when the remaining battery power is low, the following steps are included: S21”, the charger performs trickle charging on the battery; S22”, read the motor position information; S23”, the battery is charged and discharged with AC power through the electronic control and the motor, and the corresponding switch tube in the electronic control is opened according to the motor position information, and the charger supplements the battery until the battery temperature reaches the preset value; The electronic control and the battery communicate with each other to identify the battery, identify the battery temperature, and exchange information about the remaining battery capacity. The motor is directly connected to the electronic control. The electronic control reads the magnetic field position information of the stator and rotor of the motor through a position sensor installed in the motor. The motor position information is read in S21, S21' and S22" so that the stator and rotor magnetic field angle is ≤±30°.

2. The method for heating a battery of an electric two- or three-wheeled vehicle according to claim 1, wherein: In step S23 ″, the charger performs supplementary charging on the battery, which means replenishing the energy lost by the battery during the battery heating process.

Images