A dynamic estimation method for the remaining power range of an electric-assisted bicycle and a storage medium thereof

Abstract

The present invention discloses a method for dynamically estimating the remaining electric cruising range of an electric power-assisted bicycle and a storage medium thereof. The method can realize the judgment of the remaining cruising range by only relying on the voltage sensor of the central motor controller and using an algorithm to calculate the electric power consumed by the power system. The estimation method is as follows: when the electric power-assisted bicycle is powered on for the first time after initialization, the central motor controller detects the power bus voltage to calculate the SOC, and the SOE is looked up in the table based on the SOC, and the remaining mileage is calibrated as the initial value by combining the current power-assisted mode and the SOE lookup table; the central motor controller calculates the total power consumption; the power consumption is calculated per unit time, and the energy consumption of a certain distance is obtained by power integral calculation based on the area equivalence principle; the central motor controller bus voltage sensor directly detects the battery voltage change per kilometer, and the SOE difference is calculated by looking up the table, and the energy consumption value is calculated based on the rated capacity; the energy consumption value per kilometer is calculated based on the weight coefficient allocated by the ambient temperature, and the remaining mileage is calculated.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric power-assisted bicycle applications, and in particular relates to a method for dynamically estimating the remaining power range of an electric power-assisted bicycle and a storage medium thereof. Background Art

[0002] Electric-assisted bicycles use batteries to assist in riding. Since they rely on batteries, the calculation of the remaining battery life can help riders judge the distance and avoid running out of power affecting riding. The existing technology generally sets the rated riding distance and then obtains the remaining battery life through the remaining power. For example, the theoretical range of a full-charged bicycle is 100km, and the remaining power is 50% (normalized), which means the remaining range = 50% × 100km = 50km; but due to different factors such as terrain and manpower, the actual riding status has a great deal of uncertainty in determining the remaining battery life. Using the remaining power for proportional calculation has a large error and cannot meet the user's need for accurate judgment. Summary of the invention

[0003] In order to make up for the shortcomings of the prior art, the present invention provides a method for dynamically estimating the remaining power range of an electric-assisted bicycle and a storage medium thereof, which can dynamically adjust the remaining range in real time according to factors such as actual road conditions, temperature, user habits and riding speed, so that the range display is more consistent with the actual range effect. The specific technical solutions of the present invention are as follows:

[0004] An object of the present invention is to provide a method for dynamically estimating the remaining power range of an electric-assisted bicycle, comprising the following steps:

[0005] S1. When the electric-assisted bicycle is powered on for the first time after initialization, the central motor controller detects the power bus voltage and calculates the SOC (remaining power percentage). The SOE value (remaining energy percentage) is obtained by looking up the table based on the SOC value (remaining power percentage). The remaining mileage is calibrated as the initial value by combining the current power-assisted mode and the SOE table lookup;

[0006] S2. The mid-mounted motor controller calculates the total power consumption;

[0007] S3. Calculate the power consumption per unit time, and calculate the energy consumption of a certain distance by power integration based on the area equivalence principle;

[0008] S4. The bus voltage sensor of the central motor controller directly detects the battery voltage change per kilometer, calculates the SOE difference by looking up the table, and calculates the energy consumption value based on the rated capacity;

[0009] S5. Calculate the energy consumption per kilometer based on the weighted calculation of the ambient temperature and use it to calculate the remaining mileage.

[0010] Furthermore, in step S2, the total power calculation formula is:

[0011] ,

[0012] in, is the total power, unit is W; is the DC power, is the ECU (Electronic Control Unit) power, is the lamp power; and is a fixed value, which accumulates power consumption according to the current state; In a state of constant change, but It can be deduced based on the motor status and calibration data; The formula is:

[0013] ,

[0014] in, is the DC power, is the power conversion factor, is the mechanical power of the motor, unit: W, the calculation formula is as follows:

[0015] ,

[0016] In the formula, is the speed of the mid-mounted motor, unit: rpm; is the torque of the mid-mounted motor, in N·m. It can be estimated based on the current sensor sampling value of the mid-mounted motor controller. When the three-phase current coordinates are transformed into the rotating coordinate system, the torque is calculated based on the motor parameters. The general reference formula is as follows:

[0017] ,

[0018] in, is the number of motor pole pairs, is the motor d-axis inductance, is the motor q-axis inductance, is the permanent magnet flux parameter; is the motor d-axis current, is the motor q-axis current, which is calculated by three-phase current sampling and coordinate transformation.

[0019] Furthermore, the calculation formula of step S3 is as follows:

[0020] ,

[0021] in, is the energy consumed by riding a fixed distance; n is the time consumed by riding a fixed distance, in seconds, is the unit time;

[0022] Record the energy consumption per kilometer in the current riding mode. Through the filter, the energy consumption per kilometer under the rider's riding habits can be derived. The formula is as follows:

[0023] ,

[0024] in, is the total energy consumption per 1km at present; is the total energy consumption after filtering per kilometer, when initialized for the first time is the initial calibration value; is the filter coefficient.

[0025] Further, The energy consumed for riding 1 km; 1s, no time accumulation when the speed is lower than 5km / h; is 0.2.

[0026] Furthermore, the total battery energy consumption after filtering within a unit distance in step S4 is:

[0027] ,

[0028] in, The total battery energy consumption detected for the current 1km; is the total energy consumption after filtering per kilometer, when initialized for the first time is the initial calibration value; is the filter coefficient, the filter coefficient is 0.2.

[0029] Furthermore, in step S5, the motor controller can calculate the energy consumption per kilometer by indirect estimation and direct detection, and dynamically allocate the weight coefficient according to the ambient temperature. The formula is as follows:

[0030] ,

[0031] in, It is the energy consumption value per kilometer in the current mode, and this value is updated and saved in the memory every kilometer; the weight coefficient β is selected to be related to the ambient temperature. When the ambient temperature is higher than 25°C, the weight coefficient β is 0.8; when the ambient temperature is lower than 5°C, the weight coefficient β is 0.2; when the ambient temperature is between 5°C and 25°C, the linear difference of the weight coefficient is selected.

[0032] Furthermore, in step S5, the remaining mileage can be calculated according to the following formula:

[0033] ,

[0034] in, is the remaining battery life in km; SOE is obtained based on the SOC table, with an update period of 5s and a low-pass filter frequency of 0.2Hz; C is the rated capacity of the battery.

[0035] Another object of the present invention is to provide a storage medium storing an executable program, wherein the executable program includes instructions for executing the above-mentioned method for dynamically estimating the remaining power range of an electric-assisted bicycle.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The present invention only relies on the mid-mounted motor controller to estimate the power consumption in real time without relying on the Hall current sensor at the battery end, so as to realize the judgment of the remaining cruising range; the cruising range is estimated simultaneously from the two schemes of power consumption calculation and remaining power detection, and the weight coefficient is dynamically adjusted by the ambient temperature to distribute the proportion, so as to improve the accuracy of cruising range estimation; and the method of the present invention realizes calculation based on the built-in program and can be used without networking. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of the method of the present invention;

[0039] Figure 2 The motor speed-torque-efficiency diagram of the present invention;

[0040] Figure 3 The influence of the ambient temperature on the weight coefficient of the present invention;

[0041] Figure 4 This is a comparison chart of the remaining cruising range in the test example of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0043] This embodiment provides a method for dynamically estimating the remaining power range of an electric-assisted bicycle. In this embodiment, the electric-assisted bicycle includes a battery, a mid-mounted motor, a mid-mounted motor controller, and a main control board. The storage unit of the main control board is used to store calibration data and updated energy consumption data per kilometer; the mid-mounted motor controller is used for battery voltage acquisition, initial remaining mileage estimation and its calibration method, and the mid-mounted motor controller estimates the power consumption in real time without relying on the Hall current sensor at the battery end; the mid-mounted motor controller obtains the energy consumption per kilometer through two schemes, direct measurement and indirect estimation, respectively, and improves the power consumption estimation accuracy through dynamic allocation of weight coefficients according to the ambient temperature; the mid-mounted motor controller updates the remaining mileage estimation data, and updates it with a fixed unit time or SOC change percentage.

[0044] like Figure 1 As shown, the specific steps of a method for dynamically estimating the remaining electric power range of an electric-assisted bicycle are as follows:

[0045] Step 1: When the electric bicycle is powered on for the first time after initialization, the mid-mounted motor controller detects the power bus voltage and calculates the SOC. The SOE value is obtained by looking up the SOC value in the table. The remaining mileage is calibrated as the initial value based on the current power-assist mode and the SOE table lookup.

[0046] The initial remaining mileage is calculated based on the mid-mounted motor controller of the electric-assisted bicycle. The power bus connecting the mid-mounted motor controller to the battery is relatively short (generally no more than 20 cm). The bus voltage detected by it can be directly used as the current voltage A of the battery. Combined with the full-charge standard voltage B, the remaining power percentage (SOC) is calculated according to the formula A / B, and the remaining energy percentage (SOE) is obtained as the initial value by looking up Table 1 (taking a certain model of electric-assisted bicycle as an example). In this application, the remaining power percentage SOC and the remaining energy percentage SOE are both data obtained by the battery's BMS system through experiments.

[0047] Table 1: Mapping relationship between remaining power percentage and remaining energy percentage

[0048] SOC(%) 100 98.9 96.9 94.9 92.9 90.9 88.9 86.9 84.9 82.9 SOE(%) 100 98.61 96.53 94.34 92.27 90.15 87.81 85.41 83.54 81.32 SOC(%) 80.9 78.9 76.9 74.9 72.9 70.9 68.9 66.9 64.9 62.9 SOE(%) 79.15 76.81 74.88 72.66 70.34 68.72 66.71 64.17 62.1 60.09 SOC(%) 60.9 58.9 56.9 54.9 52.9 50.9 48.9 46.9 44.9 42.9 SOE(%) 57.85 55.78 53.62 51.79 49.73 47.75 45.7 43.72 41.74 39.67 SOC(%) 40.9 38.9 36.9 34.9 32.9 30.9 28.9 26.9 24.9 22.9 SOE(%) 37.78 35.77 33.87 32.04 30.18 28.11 26.04 24.72 22.44 20.54 SOC(%) 20.9 18.9 16.9 14.9 12.9 10.9 8.9 6.9 4.9 2.9 SOE(%) 18.78 16.31 14.55 13.19 11.15 9.48 7.69 5.82 4.15 2.12 SOC(%) 0.9 SOE(%) 0.71

[0049] The initial remaining mileage is obtained by looking up the table based on the initial SOE and the current riding mode. The table is based on the weight of the electric bicycle body + 50kg rider weight, simulated 0° inclined asphalt road friction resistance, and the whole vehicle drum test stand is calibrated at 25km / h at room temperature of 25℃.

[0050] Step 2: The mid-motor controller calculates the total power consumption.

[0051] The total power calculation formula is:

[0052] ,

[0053] In the formula, is the total power, unit is W; is the DC power, is the ECU power, is the lamp power; and is a fixed value, and the power consumption is accumulated according to the current state. In a specific example, The value is 4w. The value is 10w; It is related to the driver's riding habits, motor torque output, riding slope, wind resistance, etc., and is in a constantly changing state. It can be deduced based on the motor status and calibration data.

[0054] DC Power The formula is:

[0055] ,

[0056] in, is the power conversion coefficient, which is obtained by calibrating the motor speed-torque-efficiency diagram of the mid-mounted motor assembly on the dynamometer bench at room temperature of 25°C, such as Figure 2 As shown; is the mechanical power of the motor, unit: W, the calculation formula is as follows:

[0057] ,

[0058] In the formula, is the speed of the mid-mounted motor, unit: rpm; The torque of the mid-mounted motor, in N·m, can be estimated by various algorithms based on the current sensor sampling value of the mid-mounted motor controller. A relatively simple method is to transform the three-phase current coordinates into a rotating coordinate system and calculate the torque based on the motor parameters. The general reference formula is as follows:

[0059] ,

[0060] in, is the number of motor pole pairs, is the motor d-axis inductance, is the motor q-axis inductance, is the permanent magnet flux, and these parameters are the motor's own parameters; is the motor d-axis current, is the motor q-axis current, and these parameters are calculated by three-phase current sampling through coordinate transformation.

[0061] In summary, the total power calculation of this application relies on the mid-mounted motor controller, and the battery energy consumption is calculated based on the DC power consumed by the mid-mounted motor, the power consumed by the ECU, and the power consumed by the lights, without the need for a Hall current sensor to detect the battery current. The power consumed by the ECU and the lights is a fixed value, and the power consumed by the mid-mounted motor is first calculated mechanically based on the estimated value of the motor torque and the motor speed. The motor DC power is calculated by looking up the motor speed-torque-efficiency table as a compensation coefficient through conventional data such as the mechanical design manual.

[0062] Step 3: Calculate the power consumption per unit time, and based on the area equivalence principle, calculate the energy consumption for a certain distance through power integration.

[0063] The calculation formula is as follows:

[0064] ,

[0065] in, The energy consumed by riding a fixed distance, here the value is the energy consumption of 1km; n is the time consumed by riding a fixed distance, unit is s; The unit time is 1s here. Considering that the parking period will affect the average power consumption calculation, the time is not accumulated when the speed is lower than 5km / h.

[0066] Therefore, the energy consumption per kilometer in the current riding mode is recorded, and the energy consumption per kilometer under the riding habits of the rider can be deduced through the filter. The formula is as follows;

[0067] ,

[0068] in, is the total energy consumption per 1km at present; is the total energy consumption after filtering per kilometer, when initialized for the first time is the initial calibration value; is the filtering coefficient, and in this embodiment, the value is 0.2.

[0069] Step 4: The bus voltage sensor of the central motor controller directly detects the battery voltage change per kilometer, calculates the SOE difference by looking up the table, and calculates the energy consumption value based on the rated capacity.

[0070] The total battery energy consumption after filtering per unit distance is:

[0071] ,

[0072] in, The total battery energy consumption detected for the current 1km; is the total energy consumption after filtering per kilometer, when initialized for the first time is the initial calibration value; is the filtering coefficient, and in this embodiment, the value is 0.2.

[0073] The energy consumption per kilometer is calculated by indirect estimation and direct detection, and the appropriate weight coefficient is assigned. The formula is as follows:

[0074] ,

[0075] in, It is the energy consumption value per kilometer in the current mode. This value is updated and saved in the memory every kilometer. According to actual measurement, the weight coefficient β is highly correlated with the ambient temperature. When the ambient temperature is higher than 25℃, the battery discharge capacity is stronger and the estimated power consumption is more accurate, so the weight coefficient β is selected as 0.8. When the ambient temperature is lower than 5℃, the battery discharge capacity is weakened and the power consumption obtained by direct measurement is more accurate, so the weight coefficient β is selected as 0.2. When the ambient temperature is between 5℃ and 25℃, the linear difference of the weight coefficient is selected, such as Figure 3 shown.

[0076] Step 5: Calculate the energy consumption per kilometer based on the weighted ambient temperature and use it to calculate the remaining mileage.

[0077] The motor controller can calculate the energy consumption per kilometer through indirect estimation and direct detection, and dynamically allocate weight coefficients according to the ambient temperature. The formula is as follows:

[0078] ,

[0079] in, It is the energy consumption value per kilometer in the current mode, and this value is updated and saved in the memory every kilometer; the weight coefficient β is selected to be related to the ambient temperature. When the ambient temperature is higher than 25°C, the weight coefficient β is 0.8; when the ambient temperature is lower than 5°C, the weight coefficient β is 0.2; when the ambient temperature is between 5°C and 25°C, the linear difference of the weight coefficient is selected.

[0080] The remaining mileage can be calculated using the following formula:

[0081] ,

[0082] in, is the remaining battery life, km; SOE is obtained based on the SOC table, with an update period of 5s and a low-pass filter frequency of 0.2Hz; C is the rated capacity of the battery.

[0083] Based on the area equivalence principle, the product of the total power consumed per unit time and the unit time is taken as the energy consumption, the battery power consumption is deduced based on the battery power loss coefficient, and the bicycle power consumption per kilometer is estimated based on the GPS / rear wheel speed; the SOC change per kilometer is measured and the SOE difference is calculated as the bicycle power consumption per kilometer. The energy consumption per kilometer calculated by the two is weighted and deeply filtered, and the dynamic remaining cruising range is calculated based on the remaining battery energy, which is used as the final output of the remaining cruising range value.

[0084] For example, in a specific embodiment, when the actual remaining distance of riding is 40 km at an ambient temperature of 15°C, The average is 200w, and it takes 144s to ride 1km, so the power consumption per kilometer is calculated. The power consumption per kilometer is 8wh / km, and the power consumption in the first 1km is 8.5wh / km, so the power consumption per kilometer is estimated. 8.4 wh / km; direct measurement shows that SOE decreases by 1.0%, SOE decreases by 0.9% in the first 1km, and the calculated power consumption per kilometer is The battery SOE is 42.5% at this moment, and the remaining power is 345wh. If the remaining cruising range is 42.5km by directly measuring the SOE, the remaining dynamic cruising range is 39.2km by weighting it by 50% using the method of the present invention, which has a higher estimation accuracy.

[0085] like Figure 4 As shown, taking the prior art (i.e., the endurance scheme which only uses the existing remaining battery power to compare with the distance) as the control group, the actual endurance mileage of the scheme is compared, and the actual endurance is basically consistent with the calculation result of the method of the present invention. The results prove that the present invention can greatly improve the accuracy of the remaining endurance mileage. Example 2

[0086] This embodiment provides a storage medium, which is arranged on a main control board and stores an executable program therein. The executable program includes instructions for executing a method for dynamically estimating the remaining power range of an electric-assisted bicycle in Embodiment 1.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for dynamically estimating the remaining power range of an electric-assisted bicycle, characterized in that: The following steps are involved: S1. After the electric bicycle is initialized and powered on for the first time, the mid-mounted motor controller detects the power bus voltage and calculates the SOC. The SOE value is obtained by looking up the table based on the SOC value. The remaining mileage is calibrated as the initial value by combining the current power-assist mode and the SOE table lookup; S2. The mid-mounted motor controller calculates the total power consumption; S3. Calculate the power consumption per unit time, and according to the area equivalence principle, calculate the energy consumption of the corresponding distance through power integration; the calculation formula is as follows: Among them, Δw is the energy consumed by riding a fixed distance; n is the time consumed by riding a fixed distance, unit s, Δt is the unit time, P total is the total power; Record the energy consumption per kilometer in the current riding mode, and derive the energy consumption per kilometer under the rider's riding habits through the filter. The formula is as follows: w pkm_est_flt =α*w pkm_est +(1-a)w pkm_est_flt , Among them, w pkm_est is the total energy consumption per 1km at present; w pkm_est_flt is the total energy consumption after filtering per kilometer, when first initialized w pkm_est_flt is the initial calibration value; α is the filter coefficient; S4. The bus voltage sensor of the central motor controller directly detects the battery voltage change per kilometer, calculates the SOE difference by looking up the table, and calculates the energy consumption value based on the rated capacity; the total battery energy consumption after filtering per unit distance is: w pkm_calc_flt =σ*w pkm_calc +(1-σ)w pkm_calc_flt , Among them, w pkm_calc is the total battery energy consumption detected for the current 1km; w pkm_calc_flt is the total energy consumption after filtering per kilometer, when first initialized w pkm_calc_flt is the initial calibration value; σ is the filter coefficient, and the filter coefficient σ is 0.2; S5. The energy consumption per kilometer is calculated based on the weighted ambient temperature, and the remaining mileage is calculated based on this. The motor controller calculates the energy consumption per kilometer through indirect estimation and direct detection, and dynamically allocates the weight coefficient based on the ambient temperature. The formula is as follows: w pkm_fnl =β*w pkm_est_flt +(1-β)w pkm_calc_flt , Among them, w pkm_fnl It is the energy consumption value per kilometer in the current mode, and this value is updated and saved in the memory every kilometer; the weight coefficient β is selected to be related to the ambient temperature. When the ambient temperature is higher than 25°C, the weight coefficient β is 0.8; when the ambient temperature is lower than 5°C, the weight coefficient β is 0.2; when the ambient temperature is between 5°C and 25°C, the linear difference of the weight coefficient is selected.

2. The method for dynamically estimating the remaining power range of an electric-assisted bicycle according to claim 1, characterized in that: In step S2, the total power calculation formula is: P total =P dc +P ecu +P lamp , Among them, P total is the total power, in W; P dc is the DC power, P ecu is the ECU power, P lamp is the lamp power; P ecu With P lamp is a fixed value, which accumulates power consumption according to the current state; P dc In a state of constant change, but P dc Derived based on motor status and calibration data; P dc The formula is: P.S dc JP mac / η mac_dc , Among them, P dc is the DC power, η mac_dc is the power conversion factor, P mac is the mechanical power of the motor, unit: W, the calculation formula is as follows: P mac =T e *Spd rpm / 9.55, Where, Spd rpm is the speed of the mid-mounted motor, unit: rpm; T e is the torque of the mid-mounted motor, in N·m, estimated based on the current sensor sampling value of the mid-mounted motor controller. When the three-phase current coordinates are transformed into the rotating coordinate system, the torque is calculated based on the motor parameters. The general reference formula is as follows: T e =1.5n p I q [(L d -L q )i d +ψ f ], Among them, n p is the number of motor pole pairs, L d is the motor d-axis inductance, L q is the motor q-axis inductance, ψ f is the permanent magnet flux parameter; i d is the motor d-axis current, i q is the motor q-axis current, which is calculated by three-phase current sampling and coordinate transformation.

3. The method for dynamically estimating the remaining power range of an electric-assisted bicycle according to claim 1, characterized in that: Δw is the energy consumed in riding 1 km; Δt is 1s, and time is not accumulated when the speed is lower than 5 km / h; α is 0.

2.

4. The method for dynamically estimating the remaining power range of an electric-assisted bicycle according to claim 1, characterized in that: In step S5, the remaining mileage is calculated according to the following formula: L remain =SOE*C / w pkm_fnl , Among them, L remain is the remaining battery life in km; SOE is obtained based on the SOC table, with an update period of 5s and a low-pass filter frequency of 0.2Hz; C is the rated capacity of the battery.

5. A storage medium storing an executable program, characterized in that: The executable program includes instructions for executing a method for dynamically estimating the remaining power range of an electric-assisted bicycle as described in claim 1.

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