A method for switching control of peak power and continuous power of a power battery

Abstract

The application discloses a power battery peak power and continuous power switching control method, which divides power switching into a peak power descending to continuous power control stage and a continuous power rising to peak power control stage; the continuous power rising to peak power control stage: power output is performed according to a set rising rate for rising from continuous power to peak power; the peak power descending to continuous power control stage: the peak power gradually descends to continuous power in the stage, and a descending rate is adjusted according to power volume or current volume. The application has the advantages that the problem of the switching of the peak power and the continuous power being too fast to cause a poor vehicle experience is solved, battery abuse is avoided, and the service life of the battery is affected. Power volume or current volume is adopted to perform smooth switching of power, the peak power and the continuous power can be smoothly switched without mutation, the vehicle experience is improved, and the battery is protected.

Description

Technical Field

[0001] This invention relates to the field of automotive battery power control, and in particular to a method for switching control between peak power and continuous power of a power battery. Background Technology

[0002] Currently, battery power is typically provided by the battery manufacturer based on measured data from the cells, including a power map (MAP). This map includes short-term instantaneous power (peak power) and long-term continuous power (continuous power). Peak power is generally available in 2-second, 5-second, 10-second, and 30-second ranges; continuous power is generally available in 60-second, 80-second, 100-second, and 180-second ranges. Peak power is generally 2 to 6 times the continuous power. For energy-type batteries, peak power is generally 2 to 3 times the continuous power, while for power-type batteries, peak power is generally 4 to 6 times the continuous power. Peak power is mainly used during vehicle acceleration, periods of high power demand in short periods, while continuous power is mainly used during vehicle cruising or periods of lower power demand.

[0003] How to use these power parameters within the battery's allowable range is a complex logic. Generally, BMS manufacturers use a timed switching method for this power, such as using 10-second peak power and 60-second continuous power. During initialization, the BMS sends the 10-second peak power to the vehicle's HCU / VCU, and when a certain fixed time (e.g., 10 seconds) is reached, it directly switches to the 60-second continuous power. After a fixed period of time (e.g., 10 seconds), another 10 seconds of power is sent to the vehicle. This cycle repeats. The switching between 10-second and 60-second power uses a linear switching method at a certain rate (power is reduced or increased at a certain rate, which can be calibrated). Some BMS manufacturers use a conditional switching method, that is, 10-second peak power is sent during initialization. When the actual power used exceeds the 30-second peak power but is less than the 10-second peak power for a certain period of time (e.g., 10 seconds), the power is switched from 10-second power to 30-second power. When the actual power exceeds the 60-second continuous power but is less than the 30-second peak power for a certain period of time (e.g., 30 seconds), the power is switched to continuous power. After another certain period of time (e.g., 10 seconds), it switches back to 10-second power. This cycle repeats. The power switching uses a certain rate to reduce or increase power.

[0004] The above power switching method has a problem: it uses a linear increase or decrease in power. When the ratio of peak power to continuous power is large, the power jump is significant, leading to a stall issue at high speeds in pure electric mode. Specifically, when the vehicle accelerates, the actual power consumption is high; if the power switch from peak to continuous power is repeated every 10 seconds, the power suddenly drops, causing the vehicle to lose speed and resulting in a high-speed stall, leading to a poor customer experience. If the switching is too slow, it may abuse the battery, affecting its lifespan. Furthermore, a very slow switching time is excessive, impacting the vehicle's ability to accelerate again or continuously. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for controlling the switching between peak power and continuous power of a power battery. This method is used to solve the problem of poor user experience caused by excessively rapid switching between peak power and continuous power, while also preventing battery abuse and affecting battery life.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a power battery peak power and continuous power switching control method, which divides the power switching into a stage from peak power decrease to continuous power control and a stage from continuous power increase to peak power control;

[0007] From continuous power to peak power control phase: Power output is performed by increasing from continuous power to peak power according to the set recovery rate;

[0008] Peak power to continuous power control phase: In this phase, the peak power gradually decreases to continuous power, and the rate of decrease is adjusted according to the power volume or current volume.

[0009] The control phase from continuous power to peak power: The continuous power is restored to the peak power at a linear recovery rate until the peak power is reached in 10 seconds.

[0010] The linear recovery rate is pre-calibrated.

[0011] During vehicle initialization or acceleration, power supply control is performed using 10 seconds of peak power, followed by a transition from peak power to continuous power control.

[0012] The phase from peak power reduction to continuous power control includes: using 10s peak power to control battery power; when the actual discharge power is greater than the 30s peak discharge power, the excess is included in the discharge power volume; when the actual discharge power volume is equal to the 10s discharge allowable power volume, the power is reduced to the 30s power.

[0013] During the peak power to continuous power control phase, after the power drops to 30s, it continues to drop to continuous power. The rate of decrease depends on the actual discharge power volume. When the actual discharge power is greater than the continuous discharge power but less than the 10s peak power, the portion exceeding the continuous power is included in the discharge power volume. When the actual discharge power volume is equal to the 30s discharge allowable power volume, the power drops to continuous power.

[0014] If feedback power occurs at any time during the continuous power control phase after the peak power drops, or if the actual power is less than the continuous power for 3 seconds, the power will be restored to the 10-second power according to the set recovery rate.

[0015] Greater than P 30S and less than P 10S The formula for calculating the actual power volume is:

[0016] .

[0017] P 实际 P represents the actual power of the entire vehicle. 30S The peak power allowed for 30 seconds.

[0018] Greater than P 持续 And less than P 30S The actual power volume calculation formula is:

[0019] ;

[0020] P 持续 For the allowable continuous power, P 持续 For the allowable continuous power, P 30S The peak power allowed for 30 seconds.

[0021] The advantages of this invention are: it solves the problem of poor driver experience caused by excessively rapid switching between peak power and continuous power, while also preventing battery abuse and extending battery life. It employs the integral of power over time, i.e., the power volume or current volume method, to smoothly switch power. Peak power and continuous power can switch smoothly without abrupt changes, improving both the overall vehicle experience and battery protection. Attached Figure Description

[0022] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0023] Figure 1 Actual power volume diagram;

[0024] Figure 2 Battery current allowed power switching diagram. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0026] This patent employs either the power volume method or the current volume method for smooth power switching, eliminating issues of switching being too fast or too slow. Battery power is typically characterized by power MAP and current MAP. The battery function MAP serves as the data source for power switching, and its testing method is as follows:

[0027] A battery's power map (MAP) is derived from the measured data of the individual cells. Generally, the battery pack's map is converted from the measured data of the individual cells or derived from measured data at the battery pack level. This power is measured under specific conditions, such as discharge current and power map.

[0028] Taking 25℃, 50% SOC, and 10s discharge as an example:

[0029] 1. Adjust the battery cell capacity to 50% SOC;

[0030] 2. Adaptable to environments up to 25℃;

[0031] 3. Within the safe current range, test the discharge current for 10 seconds under constant current or until the voltage reaches the discharge cutoff voltage;

[0032] 4. If the discharge time is less than 10 seconds, restore the SOC to 50% and then reduce the discharge current to repeat step 3. If the discharge end voltage is greater than the discharge cutoff voltage, increase the discharge current within the safe current range and repeat step 3. Continue until the discharge end voltage is approximately equal to the discharge cutoff voltage after 10 seconds of discharge, and record the current as Imax.

[0033] 5. The limiting current at this temperature and SOC is Imax; the limiting power Pmax = V * Imax;

[0034] 6. Test Imax at different temperatures, SOCs, and times, calculate Pmax, and generate current and power maps; the current and power maps are used as data sources for power switching.

[0035] The power volume method uses the integral of power over time, while the current volume method uses the integral of current over time. This patent mainly discusses the power volume method, while the current volume method is similar to the power volume method.

[0036] The actual power volume of the vehicle discharge is the integral of the actual discharge power over time, see... Figure 1 When the current is positive, it is the discharge power; when the current is negative, it is the feedback power.

[0037] The battery's current allowable power is divided into 5 segments: segment AB, segment BC, segment CD, segment DE, segment EF, and the subsequent curves repeat cyclically.

[0038] The power output of the AB generator is the peak power output over 10 seconds. The position of point B can be calibrated to ensure the vehicle's 0-100 km / h acceleration performance. The 10-second peak power output begins when the vehicle is powered on. The position of point B is determined based on the vehicle's 0-100 km / h acceleration requirements. For example, if the vehicle's 0-100 km / h acceleration time is 8 seconds, the position of point B can be set to at least the position corresponding to 8 seconds.

[0039] In segment BC, the power gradually decreases from 10 seconds to 30 seconds. The rate of decrease depends on the actual discharge power volume. The initial available power volume is P10s. Depending on the actual usage speed, if usage is fast, the remaining available power volume decreases quickly; if usage is slow, the remaining available power volume decreases slowly. When the actual discharge power exceeds the 30-second discharge power, the excess is included in the discharge power volume (the excess is calculated by subtracting the 30-second power from the actual power and then integrating it over time). When the actual discharge power volume (i.e., the volume obtained by calculating the excess) equals the allowable 10-second discharge power volume (i.e., 10 * (P10s - P30s)), the power decreases to the 30-second power. The power decrease from 10 seconds to 30 seconds is controlled by BD = Max(K1, K2).

[0040] In segment BC, the power gradually decreases from 10s to 30s. The rate of decrease is determined by the actual discharge power volume, and the power decrease K1 is calculated using the following formula:

[0041] .

[0042] When the actual discharge power is greater than the sustained discharge power but less than the 10-second peak power, the portion exceeding the sustained power is included in the discharge power volume (actual power minus sustained power, then integrated over time to obtain the power volume). The actual discharge power volume (the actual discharge power volume refers to the volume obtained by including the excess portion in the volume calculation) equals the 30-second allowable discharge power volume (the 30-second allowable discharge power volume is 30*P). 30s P 30s When the power is at 30s (the power level), the power decreases to the continuous power level. (The decrease in power from 30s to continuous power is controlled by K2.) The DE segment equals the continuous power, and the duration can be calibrated, usually 3~10S, to ensure that the battery does not experience undervoltage faults, while also taking into account the power performance.

[0043] The EF segment recovers from continuous power to 10-second peak power, and the recovery rate can be calibrated. Here, a linear rising strategy is adopted to increase the power from continuous power to 10-second peak power.

[0044] The current permissible power of this patent is divided into 5 segments (the specific number of segments can be adjusted appropriately, and all adjusted segments are within the scope of this patent). The most important segment is segments BC and CD, and these two segments can be merged into BD. The implementation method of the current permissible power segments sent by the BMS to the whole vehicle is as follows.

[0045] 1. AB = P 10S

[0046] 2. BD = Max(K1, K2)

[0047]

[0048]

[0049]

[0050]

[0051] P 10S ------------10S Allowable Peak Power

[0052] P 30S ------------30S Allowable Peak Power

[0053] P 持续 Permissible continuous power

[0054] P 实际 ------------Actual power of the whole vehicle

[0055] W 10S ------------Greater than P 30S and less than P 10S Actual power volume

[0056] W 30S ------------Greater than P 持续 And less than P 30S Actual power volume

[0057] K1------------Permissible power calculated based on 10S peak power and actual power usage volume

[0058] K2------------Permissible power calculated based on 30-second peak power and actual power usage volume.

[0059] K1 represents the permissible power for segment BC, and its function is to determine the curve value for segment BD.

[0060] K2 represents the allowable power for segment CD, and its function is to determine the curve value for segment BD.

[0061] Theoretically, segment BD consists of two independent curves: segment BC calculated by K1 and segment CD calculated by K2. However, in practice, segments BC and CD can be merged into one curve, i.e., the larger value of K1 and K2 is used as segment BD.

[0062] 3. DE = P 持续 Duration can be calibrated

[0063] 4. EF is the linear power recovery range, which can recover at a certain rate and can be calibrated.

[0064] 5. Segments AB, BC, CD, DE, and EF represent the entire power reduction and recovery process, which repeats continuously. During the power reduction, if feedback power occurs at any time or the actual power is less than the continuous power for 3 seconds, the power will recover to the 10-second power according to the recovery strategy of segment EF.

[0065] This patented power switching method avoids unreasonable power reduction when power is not actually used, and also avoids sudden power drop when frequently using high power. It solves the problem of uneven power allowance of the whole vehicle, ensuring both vehicle performance and battery protection.

[0066] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A method for controlling the switching between peak power and continuous power of a power battery, characterized in that: The power switching is divided into a phase from peak power descent to continuous power control and a phase from continuous power rise to peak power control. From continuous power to peak power control phase: Power output is performed by increasing from continuous power to peak power according to the set recovery rate; Peak power descent to continuous power control phase: In this phase, the peak power gradually decreases to continuous power, and the rate of decrease is adjusted according to the actual power capacity. The phase from peak power reduction to continuous power control includes: using 10s peak power to control the battery power; when the actual discharge power is greater than the 30s peak discharge power, the excess is included in the discharge power volume; when the actual discharge power volume is equal to the 10s discharge allowable power volume, the power is reduced to the 30s power. During the peak power to continuous power control phase, after the power drops to 30s, it continues to drop to continuous power. The rate of decrease depends on the actual discharge power volume. When the actual discharge power is greater than the continuous discharge power but less than the 10s peak power, the portion exceeding the continuous power is included in the discharge power volume. When the actual discharge power volume is equal to the 30s discharge allowable power volume, the power drops to continuous power. Greater than and less than The formula for calculating the actual power volume is: ； This refers to the actual power of the entire vehicle. For the 30-second allowable peak power, For 10 seconds, the allowable peak power; Greater than and less than The actual power volume calculation formula is: ； For the permissible continuous power, The allowable peak power is 30 seconds. When the peak power drops from 10s to 30s, the permissible power is... Calculate using the following formula: ； When the peak power drops from 30s to continuous power, the permissible power is... Calculate using the following formula: ； From the overall stage of the 10-second peak power drop to the sustained power, the current allowable output power is taken as... and The larger value in the range.

2. The method for switching between peak power and continuous power of a power battery as described in claim 1, characterized in that: The control phase from continuous power to peak power: The continuous power is restored to the peak power at a linear recovery rate until the peak power is reached in 10 seconds.

3. A method for switching control between peak power and continuous power of a power battery as described in claim 1 or 2, characterized in that: The linear recovery rate is pre-calibrated.

4. A method for switching control between peak power and continuous power of a power battery as described in claim 1 or 2, characterized in that: During vehicle initialization or acceleration, power supply control is performed using 10 seconds of peak power, followed by a transition from peak power to continuous power control.

5. The method for switching between peak power and continuous power of a power battery as described in claim 1, characterized in that: If feedback power occurs at any time during the continuous power control phase after the peak power drops, or if the actual power is less than the continuous power for 3 seconds, the power will be restored to the 10-second power according to the set recovery rate.

Images