Electric Vehicle Power Calculation System and Method

Abstract

A power calculation system and method for an electric vehicle, wherein the power calculation system includes a battery, a power calculation module, and a storage unit. The power calculation module is electrically connected to the battery and includes a current sensing unit, a voltage sensing unit, and a processor. The processor is electrically connected to the current sensing unit and the voltage sensing unit. The current sensing unit detects and obtains the current value of the battery, and the voltage sensing unit detects and obtains the voltage value of the battery. The storage unit stores a first calculation formula and a second calculation formula. The processor calculates the current power value of the battery based on the current value and the voltage value.

Description

[Technical Field]

[0001] This invention relates to a power calculation system and method, and more particularly to a power calculation system and method for an electric vehicle. [Previous Technology]

[0002] Most of the electric vehicles currently on the market (such as electric scooters or electric motorcycles) use batteries as their power source.

[0003] Generally, common methods for calculating battery capacity include the coulomb counting method or the open-circuit voltage conversion method. The coulomb counting method calculates battery capacity by measuring the change in battery current over time. However, this method requires continuous accumulation of battery current values, leading to increased system energy consumption and potentially accumulating errors that affect the accuracy of battery capacity calculation. The open-circuit voltage conversion method directly measures the battery voltage and calculates the battery capacity based on that voltage. However, because the battery voltage changes with actual load conditions, the calculation of battery capacity is prone to significant errors. [Summary of the Invention]

[0004] In view of the above, in one embodiment, a power calculation system for an electric vehicle is provided, including a battery, a power calculation module, and a storage unit. The power calculation module is electrically connected to the battery and includes a current sensing unit, a voltage sensing unit, and a processor. The processor is electrically connected to the current sensing unit and the voltage sensing unit. The current sensing unit detects and obtains the current value of the battery, and the voltage sensing unit detects and obtains the voltage value of the battery. The processor calculates the current power value of the battery based on the current value and the voltage value. The storage unit is electrically connected to the processor and stores a first calculation formula and a second calculation formula. The first calculation formula is different from the second calculation formula. When the current value is less than a threshold, the processor substitutes the voltage value into the first calculation formula to calculate the current power value; when the current value is greater than or equal to the threshold, the processor substitutes the current value and the voltage value into the second calculation formula to calculate the current power value.

[0005] In another embodiment, a method for calculating the battery charge of an electric vehicle is provided, including: detecting and obtaining the current value of the battery with a current sensing unit; detecting and obtaining a voltage value of the battery with a voltage sensing unit; and calculating the current charge value of the battery based on the current value and the voltage value.

[0006] In summary, the electric vehicle power calculation system and method of the present invention obtains the current current value and voltage value of the battery by detecting the current value and voltage value, and calculates the current power value of the battery based on the current value and voltage value. This can avoid the problem of current accumulation error and improve the accuracy of calculation. Moreover, the system does not need to continuously record the current, which can further reduce energy consumption.

Implementation Method

[0007] Figure 1 is a system block diagram of an embodiment of the power calculation system of the present invention. As shown in Figure 1, the power calculation system 1 of the embodiment of the present invention includes a battery 10 and a power calculation module 21. The power calculation system 1 can be applied to electric vehicles, such as electric scooters, electric motorcycles, electric bicycles, or electric skateboards, etc.

[0008] In some embodiments, the battery 10 may be a lithium-ion battery, a lithium iron phosphate battery, or a lead-acid battery, etc. The power calculation module 21 is electrically connected to the battery 10, and the battery 10 can be used to provide the power required by the power calculation module 21. In addition, the battery 10 can also be used to provide the power required by other components of the electric vehicle, which may include, but are not limited to, the dashboard, turn signals, headlights, motor, and electronic locks.

[0009] As shown in Figure 1, the power calculation module 21 is used to calculate the power of the battery 10. The power calculation module 21 includes a current sensing unit 22, a voltage sensing unit 23 and a processor 24. The current sensing unit 22 is used to detect and obtain a current value of the battery 10, and the voltage sensing unit 23 is used to detect and obtain a voltage value of the battery 10.

[0010] Figure 2 is a system block diagram of another embodiment of the power calculation system of the present invention. As shown in Figure 2, in this embodiment, the power calculation system 1 includes a motor controller 20 and a motor 40. The motor controller 20 is electrically connected to the motor 40, and the motor controller 20 is responsible for controlling the rotational speed of the motor 40 (e.g., acceleration, deceleration, and maintaining stable operation), and is an existing controller of the electric vehicle. The power calculation module 21 can be built into the motor controller 20 (as shown in Figure 2). That is, the components in the power calculation module 21 (including the current sensing unit 22, the voltage sensing unit 23, and the processor 24) are the existing electronic components of the motor controller 20. In this way, this embodiment utilizes the existing hardware of the motor controller 20 to calculate the power of the battery 10, which can achieve the advantage of significant cost savings. However, the above embodiment is only an example, and the power calculation module 21 and the motor controller 20 can also be independent components.

[0011] In some embodiments, the processor 24 of the power calculation module 21 may be a central processing unit (CPU) consisting of a single core or multiple cores, other programmable general-purpose or special-purpose microprocessors, digital signal processors (DSPs), programmable controllers, application-specific integrated circuits (ASICs), programmable logic devices (PLDs), or other similar devices.

[0012] As shown in Figure 1, the processor 24 is electrically connected to the current sensing unit 22 and the voltage sensing unit 23. The processor 24 calculates a current charge value of the battery 10 based on the measured current and voltage values. For example, the processor 24 can input the measured current and voltage values ​​into a charge calculation formula to calculate the current charge value. In other words, the processor 24 of the charge calculation system 1 of this embodiment calculates the current charge value of the battery 10 based on the current and voltage values ​​of the battery 10 simultaneously. Therefore, by using the calculation method that utilizes the current current and voltage values ​​simultaneously, this embodiment of the invention does not need to calculate the current charge value by accumulating the current value. This avoids the problem of error accumulation and reduces energy consumption because it does not require continuous measurement and recording of the current value of the battery 10. On the other hand, when the electric vehicle is under different load conditions, the voltage output by the battery 10 will vary with the actual load. If the remaining power is estimated only by the voltage value, the estimated power will fluctuate wildly depending on the load conditions. However, since the power calculation formula of this embodiment considers both current and voltage values, it can avoid errors and improve the accuracy of the power calculation of the battery 10. The following further explains the calculation method of the power calculation system 1 of this embodiment with reference to the drawings.

[0013] Figure 3 is a flowchart of the steps of the first embodiment of the power calculation method of the present invention. As shown in Figure 3, the power calculation method of this embodiment includes steps S01 to S03. In step S01, a current value of the battery 10 is detected and obtained by the current sensing unit 22, wherein the current value is the current value output by the battery 10 to the motor 40 and detected by the power calculation module 21. In step S02, a voltage value output by the battery 10 is detected and obtained by the voltage sensing unit 23. In some embodiments, the order of the above steps S01 and S02 can be interchanged or performed simultaneously, which is not limited.

[0014] As shown in Figure 3, after steps S01 and S02, step S03 can be executed: calculating a current charge value of battery 10 based on the current and voltage values. Referring to Figures 1 and 2, step S03 can be executed by a processor 24. In this embodiment, the charge calculation module 21 includes a storage unit 25, which is electrically connected to the processor 24. The storage unit 25 can pre-store a charge calculation formula. The storage unit 25 can be, for example, any type of fixed or removable random access memory (RAM), read-only memory (ROM), flash memory, hard disk, or other similar device. The processor 24 can input the current and voltage values ​​of the battery 10 into the charge calculation formula to calculate the current charge value of battery 10. In some embodiments, the current charge value can be expressed as a charge percentage (%), for example, when the current charge value is 80, it means that battery 10 has 80% charge remaining.

[0015] As shown in Figures 1 and 2, the power calculation system 1 may include a display module 30, such as the dashboard of an electric vehicle. The power calculation module 21 may include a communication unit 26, which may be a wireless communication unit, such as a Bluetooth module, Wi-Fi module, LoRa module, Zigbee module, etc. Alternatively, the communication unit 26 may also be a wired communication unit, such as a CAN Bus (Controller Area Network). The communication unit 26 may be connected to the processor 24 and the display module 30 via wired or wireless means. After the processor 24 calculates the current power value of the battery 10, it can transmit it to the display module 30 through the communication unit 26, so that the display module 30 can display the current power value, allowing the user to know the battery status at any time, helping the user to better plan the route, improve driving safety, and plan charging schedules.

[0016] Figure 4 is a flowchart of the steps of the second embodiment of the power calculation method of the present invention. As shown in Figure 4, in this embodiment, step S03 may include steps S031 and S032. Step S031 or step S032 can be executed after steps S01 and S02. Step S031 includes: when the current value is less than a threshold, the voltage value is substituted into the first calculation formula to calculate the current power value. Step S032 includes: when the current value is greater than or equal to the threshold, the current value and voltage value are substituted into the second calculation formula to calculate the current power value. Referring to Figure 1, in this embodiment, the power calculation formula may include the aforementioned first calculation formula and second calculation formula. The storage unit 25 of the power calculation module 21 can store the first calculation formula and the second calculation formula. The first calculation formula is different from the second calculation formula, but this is not limited. The power calculation formula may also be other calculation formulas different from the first calculation formula and the second calculation formula. The threshold may be a preset current value and stored in the storage unit 25. In some embodiments, the threshold may be 1 / 10 of the maximum discharge current value of battery 10, 1 / 5 of the maximum discharge current value, or a value between 1 / 10 and 1 / 5 of the maximum discharge current value, to determine the load state of the electric vehicle and battery 10. For example, when the maximum discharge current value of battery 10 is 20 amperes (A), the threshold may be set to a specific value between 2 amperes (A) and 4 amperes (A).

[0017] As shown in Figures 1 and 4, steps S031 and S032 can be executed by the processor 24 of the power calculation module 21. When the processor 24 determines that the current value of the battery 10 is less than the threshold, that is, the battery 10 is in a state of no load or low load, the processor 24 only needs to input the voltage value of the battery 10 into the first calculation formula to calculate the current power value of the battery 10. When the processor 24 determines that the current value of the battery 10 is greater than or equal to the threshold, that is, the battery 10 is in a state of high load, the processor 24 must input both the current value and the voltage value into the second calculation formula to calculate the current power value of the battery 10. In other words, when the current value of the battery 10 is greater than or equal to the threshold, the calculation of the current power value must consider both the current value and the voltage value. Therefore, the second embodiment of the present invention further considers the load state of the battery 10 and uses the current value and voltage value into different calculation formulas to calculate the current charge value of the battery 10. When the current value is small (i.e. the load is low), the current charge value is estimated only by the voltage value, which can further improve the accuracy of the calculation.

[0018] Figure 5 is a flowchart of the steps for establishing the first operational formula according to an embodiment of the present invention, and Figure 7 is a graph showing the relationship between power and voltage in an embodiment of the power calculation method of the present invention. As shown in Figure 5, the above-mentioned first operational formula can be established by a first processing program, which includes steps S11 to S14. Step S11 can be executed first. Step S11 is a discharge step: the fully charged battery 10 releases a predetermined current and continues for a first time. In step S11, the electric vehicle and the battery 10 are not connected to a load. The predetermined current and the first time can be determined according to actual needs. For example, the predetermined current can be 1 / 10 to 1 / 5 of the maximum discharge current value of the battery 10, or the predetermined current can also be the maximum discharge current value of the battery 10. The first time can be a specific time between 1 minute and 3 minutes. After step S11, step S12 can be executed. Step S12 is a resting step: the battery 10 is left to rest for a second time, and the voltage change value is recorded. In step S12, the second time can be determined according to actual needs, for example, the second time can be a specific time from half an hour to two hours, and the voltage value can be recorded simultaneously after the second resting time. After step S12, step S13 can be executed. Step S13 is a repeating step: the discharge step (step S11) and the resting step (step S12) are repeated continuously to obtain the first voltage change information, which includes multiple voltage change values. For example, as shown in Figure 7, curve C1 is the voltage and charge curve of the battery 10 generated by executing steps S11 to S13. As can be seen from curve C1, during the execution of steps S11 to S13, the charge and voltage of the battery 10 will gradually decrease, and the voltage change value can be continuously recorded to obtain the aforementioned first voltage change information. Additionally, as shown in Figure 7, the battery 10 used in this embodiment to establish the calculation formula is a lithium-ion battery, and the battery 10 has the following specifications: rated voltage 48 volts (V), rated capacity 14 ampere-hours (Ah), maximum voltage 54.6 volts (V) and maximum continuous discharge current 20 amperes (A). However, this is not a limitation, and the selection of battery 10 can be determined according to the actual product application.

[0019] As shown in Figure 5, step S14 can be executed after steps S11 to S13 are completed until the battery 10's charge is 0. Step S14 is an establishment step: establishing a first calculation formula based on the predetermined current and first voltage change information. For example, the predetermined current and first voltage change information can be established using a polynomial approximation method to establish the first calculation formula. For example, if the battery 10 specification is used, the established first calculation formula can be Y = 0.4925X² - 34.949X + 552.66, where Y is the current charge value and X is the current voltage value of the battery 10. Therefore, when the current value of the battery 10 in the charge calculation system 1 is less than the threshold, the current voltage value of the battery 10 can be substituted into the first calculation formula to calculate the current charge value of the battery 10. However, the values ​​of the quadratic term coefficient, the linear term coefficient, and the constant in the aforementioned first calculation formula are only examples. If different specifications of battery 10 are used for establishment, the values ​​in the first calculation formula will also change accordingly.

[0020] Figure 6 is a flowchart of the steps for establishing the second operational formula according to an embodiment of the present invention. As shown in Figure 6, the above-mentioned second operational formula can be established through a second processing program, which includes steps S21 to S23. First, step S21 can be executed. Step S21 is a load step: connecting a fully charged battery 10 to a load. After step S21, step S22 can be executed. Step S22 is a release step: the battery 10 continuously releases a set current to continuously record the second voltage change information (for example, the second voltage change information can be obtained by periodically detecting the voltage value of the battery 10). For example, as shown in Figure 7, curve C2 is the voltage and charge curve of the battery 10 when the battery 10 continuously releases 5 amps (set current), curve C3 is the voltage and charge curve of the battery 10 when the battery 10 continuously releases 10 amps (set current), and curve C4 is the voltage and charge curve of the battery 10 when the battery 10 continuously releases 20 amps (set current). As can be seen from curves C2 to C4, during the execution of steps S21 and S22, the charge and voltage of the battery 10 will gradually decrease, and the voltage change value can be continuously recorded to obtain the aforementioned second voltage change information.

[0021] As shown in Figure 6, step S23 can be executed after steps S21 and S22 are performed until the battery 10's charge is 0. Step S23 is a processing step: a second calculation formula is established based on the set current and second voltage change information. For example, the set current and second voltage change information can be used to establish the second calculation formula using a polynomial approximation method. For example, if the battery 10 specifications are used, the established second calculation formula can be Y=(0.5502X 2-39.102X+651.24)+((A-10)×(0.0102X 2-0.6679X+11.125)), where Y is the current charge value, X is the current voltage value of the battery 10, and A is the current current value of the battery 10. Therefore, when the current value of the battery 10 in the charge calculation system 1 is greater than or equal to the threshold, the current current value and voltage value of the battery 10 can be substituted into the second calculation formula to calculate the current charge value of the battery 10. However, the values ​​of the quadratic term coefficient, the linear term coefficient, and the constant in the aforementioned second formula are merely examples. If the formula is established using batteries of different specifications 10, the values ​​in the second formula will also change accordingly.

[0022] In some embodiments, the second calculation formula may include a power equation and a compensation equation. For example, the power equation may be 0.5502X 2-39.102X+651.24 in the second calculation formula, and the compensation equation may be (A-10)×(0.0102X 2-0.6679X+11.125) in the second calculation formula. As shown in Figures 1 and 4, in step S032, when the current value of the battery 10 is greater than or equal to a threshold, the processor 24 can substitute the voltage value of the battery 10 into the power equation to calculate the first power value, substitute the current value and voltage value of the battery 10 into the compensation equation to calculate the second power value, and sum the first power value and the second power value to obtain the current power value. This achieves that the power calculation can be compensated according to the load condition of the battery 10 to improve the accuracy of power calculation.

[0023] Figure 8 is a flowchart of the steps of the third embodiment of the power calculation method of the present invention. As shown in Figure 8, after step S03, this embodiment can execute step S04: compare the current power value with the previous power value to obtain the power change value. After step S04, step S05 or step S06 can be executed. Step S05 includes: when the power change value is less than a threshold value, output the current power value. Step S06 includes: when the power change value is greater than the threshold value, output an adjusted power value.

[0024] Referring to Figures 1 and 8, the above steps S04 to S06 can be executed by the processor 24 of the power calculation system 1. The processor 24 can continuously calculate the power value of the battery 10 (for example, calculate the power value every 10 to 30 seconds). In step S04, each time the processor 24 obtains the current power value, it can compare it with the previously obtained power value to calculate the power change value. For example, if the current power value is 49.5% and the previous power value was 50%, the processor 24 can calculate the power change value as 0.5%.

[0025] In step S05, assuming the current battery level of battery 10 is 49.5% and the previous battery level was 50%, if the threshold value is set to 1%, the processor 24 can calculate the battery level change value as 0.5% and determine that the battery level change value is less than the threshold value, indicating that the battery level change value is still within the normal range. The processor 24 can directly output the current battery level value (49.5%) to the display module 30 for the user to view. In step S06, assuming the current battery level is 48% and the previous battery level was 50%, if the threshold value is set to 1%, the processor 24 can calculate the battery level change value as 2% and determine that the battery level change value is greater than the threshold value, indicating that the battery level change value may be abnormal. The processor 24 then outputs an adjusted battery level value (49%) to the display module 30 for display. The adjusted battery level value is the difference between the previous battery level value (50%) and the threshold value (1%) to avoid the current abnormality affecting the accuracy of subsequent battery level calculations.

[0026] In summary, the power calculation system and method of the present invention obtain the current and voltage values ​​of the battery by detecting them, and calculate the current power value of the battery based on the current and voltage values. This can avoid the problem of current accumulation error and improve the accuracy of calculation. Furthermore, the system does not need to continuously record the current, which can further reduce energy consumption.

[0027] Although the technical content of the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0028] Figure 1 is a system block diagram of one embodiment of the power calculation system of the present invention. Figure 2 is a system block diagram of another embodiment of the power calculation system of the present invention. Figure 3 is a flowchart of the steps of the first embodiment of the power calculation method of the present invention. Figure 4 is a flowchart of the steps of the second embodiment of the power calculation method of the present invention. Figure 5 is a flowchart of the steps of establishing the first operational expression in one embodiment of the present invention. Figure 6 is a flowchart of the steps of establishing the second operational expression in one embodiment of the present invention. Figure 7 is a graph showing the relationship between power and voltage in one embodiment of the power calculation method of the present invention. Figure 8 is a flowchart of the steps of the third embodiment of the power calculation method of the present invention.

Claims

1. A power calculation system for an electric vehicle, comprising: One battery; A power calculation module is electrically connected to the battery. The power calculation module includes a current sensing unit, a voltage sensing unit, and a processor. The processor is electrically connected to the current sensing unit and the voltage sensing unit. The current sensing unit detects and obtains a current value of the battery, and the voltage sensing unit detects and obtains a voltage value of the battery. The processor calculates a current power value of the battery based on the current value and the voltage value. The processor also includes a storage unit electrically connected to the processor. The storage unit stores a first operational expression and a second operational expression, wherein the first operational expression is different from the second operational expression. When the current value is less than a threshold, the processor substitutes the voltage value into the first operational expression to calculate the current power value. When the current value is greater than or equal to the threshold, the processor substitutes the current value and the voltage value into the second operational expression to calculate the current power value. The second operational expression includes a power equation and a compensation equation. When the current value is greater than or equal to the threshold, the processor substitutes the voltage value into the power equation to calculate a first power value and substitutes the current value and the voltage value into the compensation equation to calculate a second power value. The current power value is the sum of the first power value and the second power value.

2. The power calculation system for an electric vehicle as described in claim 1, wherein the threshold is 1 / 10 to 1 / 5 of the maximum discharge current value of one of the batteries.

3. The power calculation system for an electric vehicle as described in claim 1, wherein the processor compares the current power value with a previous power value to obtain a power change value, and when the power change value is less than a threshold value, the processor outputs the current power value.

4. The power calculation system for an electric vehicle as described in claim 3, wherein when the power change value is greater than the threshold value, the processor outputs an adjusted power value, the adjusted power value being the difference between the previous power value and the threshold value.

5. The power calculation system for an electric vehicle as described in claim 1 further includes a display module, the power calculation module including a communication unit connected to the processor and the display module, the display module receiving and displaying the current power value transmitted by the communication unit.

6. A method for calculating the electrical charge of an electric vehicle, comprising: Step (a): Detect and obtain a current value of a battery using a current sensing unit; Step (b): Detect and obtain a voltage value of the battery using a voltage sensing unit; And step (c): Calculate a current charge value of the battery based on the current value and the voltage value; when the current value is less than a threshold, substitute the voltage value into a first calculation formula to calculate the current charge value; when the current value is greater than or equal to the threshold, substitute the current value and the voltage value into a second calculation formula to calculate the current charge value, and the first calculation formula is different from the second calculation formula; wherein the second calculation formula includes a charge equation and a compensation equation; when the current value is greater than or equal to the threshold, substitute the voltage value into the charge equation to calculate a first charge value, substitute the current value and the voltage value into the compensation equation to calculate a second charge value, and sum the first charge value and the second charge value to obtain the current charge value.

7. The method for calculating the power of an electric vehicle as described in claim 6, wherein the threshold is 1 / 10 to 1 / 5 of the maximum discharge current value of one of the batteries.

8. The method for calculating the power of an electric vehicle as described in claim 6, wherein the first formula is established via a first processing program, the first processing program comprising: Discharge step: Discharge a predetermined current from the fully charged battery and continue for a first time; Resting step: After the battery is left to rest for a second time, a voltage change value is recorded; Repeating step: The discharging step and the resting step are repeated continuously to obtain a first voltage change information, the first voltage change information including a plurality of voltage change values; and Establishing step: The first calculation formula is established based on the predetermined current and the first voltage change information.

9. The method for calculating the power of an electric vehicle as described in claim 6, wherein the second formula is established via a second processing program, the second processing program comprising: Loading step: Connect the fully charged battery to a load; Releasing step: Continuously release a set current from the battery to continuously record a second voltage change information; and Processing step: Establish the second calculation formula based on the set current and the second voltage change information.

10. The method for calculating the power of an electric vehicle as described in claim 6 further includes step (d): comparing the current power value with a previous power value to obtain a power change value, and outputting the current power value when the power change value is less than a threshold value.

11. The method for calculating the power of an electric vehicle as described in claim 10, wherein step (d) includes: When the change in battery level exceeds the threshold value, an adjusted battery level value is output. This adjusted battery level value is the difference between the previous battery level value and the threshold value.

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