Operation method for improving utilization rate of battery discharge power supply for electro-tricycle

Abstract

The invention discloses an operation method for improving the utilization rate of a battery discharge power supply for an electro-tricycle, which belongs to the technical field of battery application, and comprises the following steps: S1, electrifying the electro-tricycle, and judging whether a battery type has a communication type through an MCU (Microprogrammed Control Unit), S2, when the battery does not have a communication function, judging whether a current voltage value is greater than a power limit point, and if yes, judging whether the current voltage value is greater than the power limit point; s3, when the battery has a communication function, calculating a battery under-voltage value and a power limiting point according to the number of battery strings, the MCU limits the input power according to the battery voltage provided by the BMS, the SOC and the allowable maximum continuous discharging current, the electric quantity is judged according to the battery voltage, a power reducing point is set, the input power of the MCU is limited, the electric energy utilization rate of the battery discharging tail end is improved, and meanwhile, the battery under-voltage value and the power limiting point are calculated according to the battery string number. In order to realize the soft undervoltage function, the MCU needs to accurately sample the bus voltage, and parameters such as the SOC of the battery and the maximum allowable continuous discharge current are obtained through the communication bus to limit the input power.

Description

Technical Field

[0001] The present invention relates to the technical field of battery application, and in particular to an operating method for improving battery discharge power utilization rate for an electric tricycle. Background Art

[0002] At present, electric tricycles use acceleration signals to drive the entire vehicle. During driving, the MCU determines the battery power based on the battery voltage. When using lithium batteries, due to the non-linear relationship between battery voltage and power, and the existence of single-cell undervoltage and cell voltage difference protection inside the lithium battery BMS, large current discharge at low battery power and low temperature is more likely to trigger the battery's single-cell undervoltage protection and cell voltage difference protection, resulting in the battery not being fully discharged and the entire vehicle being powered off. Therefore, an operating method for improving the utilization rate of battery discharge power for electric tricycles is proposed. Summary of the Invention

[0003] The object of the present invention is to provide an operating method for an electric tricycle for improving the utilization rate of battery discharge power, so as to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: an operating method for improving the utilization rate of battery discharge power for an electric tricycle, comprising the following steps:

[0005] S1. Power on the electric tricycle and use the MCU to determine whether the battery type has the communication type.

[0006] S2. When the battery has no communication function, determine whether the current voltage value is greater than the power limit point;

[0007] S21: When it is determined that the power is greater than the power limit point, the battery is defined as high power, so that the bus current is limited according to the current limit value set by the vehicle controller logic, and the electric tricycle runs normally;

[0008] S22: If it is determined that the current voltage value is less than the power limit point, it is determined whether the current voltage value is greater than the undervoltage point;

[0009] S221: When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started;

[0010] S222: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed.

[0011] S3. When the battery has communication function, the battery undervoltage value and power limit point are calculated according to the number of battery strings;

[0012] S31, when it is determined that the current voltage value is less than the power limit point, determining whether the current voltage value is greater than the undervoltage point;

[0013] S311. When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started;

[0014] S312: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed.

[0015] S32: When it is determined that the current is greater than the power limit point, determine whether the maximum continuous discharge current of the battery is greater than the MCU current limit value;

[0016] S321. When the current is greater than the MCU current limit value, it is defined that the battery can meet the power demand of the MCU, and the current is limited according to the MCU current limit value, and the electric vehicle runs normally;

[0017] S322: If the current is less than the MCU current limit value, the battery is defined as low power and cannot meet the power demand of the MCU. At this time, it is determined whether the current battery SOC is ≥ 10%;

[0018] When the battery SOC is ≥ 10%, the current is limited according to the maximum continuous discharge current allowed by the battery;

[0019] When the battery SOC is ≤10%, determine whether the current battery SOC is ≥3%;

[0020] When the battery SOC is ≥ 3%, the current is limited to 80% of the battery's allowable discharge current;

[0021] When the battery SOC is ≤ 3%, the current is limited to 50% of the battery's allowable discharge current.

[0022] As a further preferred embodiment of the present technical solution: when the battery SOC is ≥10%, current is limited according to the maximum continuous discharge current allowed by the battery to protect the battery and avoid single cell undervoltage failure caused by excessive discharge current;

[0023] Among them, when the battery SOC is ≤3%, the current is limited to 50% of the battery's allowable discharge current to further ensure continuous discharge of the battery and improve the battery's power utilization rate.

[0024] As a further preferred embodiment of the present technical solution: the low battery determination range is a single cell voltage of 10.4v-10.5v, the normal battery determination range is a single cell voltage of 10.6v-10.8v, and the high battery determination range is a single cell voltage >10.8v.

[0025] As a further preferred embodiment of the present technical solution: in S222 and S312, the target voltage is the power limit point, and the bus voltage is maintained at the power limit point during driving. During this process, the battery power gradually decreases and the current limit of the MCU gradually decreases;

[0026] The gradual decrease in battery power means that the battery output power gradually decreases.

[0027] As a further preferred embodiment of the present technical solution: the vehicle speed is gradually reduced, thereby avoiding the undervoltage protection triggered by low battery voltage due to rapid acceleration, thereby causing vehicle power interruption.

[0028] As a further preferred embodiment of the present technical solution: in S222 and S312, the error calculation formula between the actual voltage and the target voltage is:

[0029] e=Vtarget-Vactual (1)

[0030] In formula (1), e is the voltage error, Vtarget is the target voltage, and Vactual is the actual measured voltage.

[0031] As a further preferred embodiment of the present technical solution: in S222 and S312, the output regulation current calculation formula is:

[0032] Δl=Kp*e+Ki*∫ e dt(2)

[0033] In formula (2), Δl is the output current regulation amount, Kp is the proportional gain, e is the voltage error, and Ki is the integral gain.

[0034] As a further preferred embodiment of the present technical solution: in S3, the battery undervoltage value=the number of strings*the battery cell undervoltage value, and the power limit point is the battery undervoltage value+(the number of strings*0.3).

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. In the present invention, the MCU limits the input power based on the battery voltage, SOC, and maximum continuous discharge current provided by the BMS. The battery voltage is used to determine the power level, set the power reduction point, limit the MCU's input power, and improve the energy utilization rate at the end of battery discharge. At the same time, to implement the soft undervoltage function, the MCU needs to accurately sample the bus voltage and obtain parameters such as the battery's SOC and maximum continuous discharge current through the communication bus to limit the input power.

[0037] 2. In the present invention, when the power is greater than the undervoltage point, the battery is at normal power. The proportional gain and integral gain are calculated according to the error between the actual voltage and the target voltage, and the current value for maintaining the target voltage is calculated to perform current limiting, so that the bus voltage during driving is maintained at the power limit point. In this process, the battery power gradually decreases while the MCU current limit will gradually decrease, and the vehicle speed will gradually decrease, thereby avoiding the undervoltage protection triggered by the low battery voltage due to rapid acceleration, thereby causing vehicle power interruption. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an operation flow chart of an operation method for improving battery discharge power utilization rate for an electric tricycle according to the present invention;

[0039] Figure 2 This is a flowchart of the operation of a battery without a communication function in an operation method for improving battery discharge power utilization for an electric tricycle of the present invention;

[0040] Figure 3 The present invention provides an operating flow chart of an electric tricycle in which a battery has a communication function in an operating method for improving battery discharge power utilization. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0042] Example

[0043] See also Figure 1-Figure 3 The present invention provides a technical solution: an operating method for improving the utilization rate of battery discharge power for an electric tricycle, comprising the following steps:

[0044] S1. Power on the electric tricycle and use the MCU to determine whether the battery type has the communication type.

[0045] S2. When the battery has no communication function, determine whether the current voltage value is greater than the power limit point;

[0046] S21: When it is determined that the power is greater than the power limit point, the battery is defined as high power, so that the bus current is limited according to the current limit value set by the vehicle controller logic, and the electric tricycle runs normally;

[0047] S22: If it is determined that the current voltage value is less than the power limit point, it is determined whether the current voltage value is greater than the undervoltage point;

[0048] S221: When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started;

[0049] S222: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed.

[0050] S3. When the battery has communication function, the battery undervoltage value and power limit point are calculated according to the number of battery strings;

[0051] S31, when it is determined that the current voltage value is less than the power limit point, determining whether the current voltage value is greater than the undervoltage point;

[0052] S311. When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started;

[0053] S312: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed.

[0054] S32: When it is determined that the current is greater than the power limit point, determine whether the maximum continuous discharge current of the battery is greater than the MCU current limit value;

[0055] S321. When the current is greater than the MCU current limit value, it is defined that the battery can meet the power demand of the MCU, and the current is limited according to the MCU current limit value, and the electric vehicle runs normally;

[0056] S322: If the current is less than the MCU current limit value, the battery is defined as low power and cannot meet the power demand of the MCU. At this time, it is determined whether the current battery SOC is ≥ 10%;

[0057] When the battery SOC is ≥ 10%, the current is limited according to the maximum continuous discharge current allowed by the battery;

[0058] When the battery SOC is ≤10%, determine whether the current battery SOC is ≥3%;

[0059] When the battery SOC is ≥ 3%, the current is limited to 80% of the battery's allowable discharge current;

[0060] When the battery SOC is ≤ 3%, the current is limited to 50% of the battery's allowable discharge current.

[0061] In this embodiment, specifically: when the battery SOC is ≥10%, current is limited according to the maximum continuous discharge current allowed by the battery to protect the battery and avoid single cell undervoltage failure caused by excessive discharge current;

[0062] Among them, when the battery SOC is ≤3%, the current is limited to 50% of the battery's allowable discharge current to further ensure continuous discharge of the battery and improve the battery's power utilization rate.

[0063] In this embodiment, specifically: the low battery determination range is a single cell voltage of 10.4V-10.5V, the normal battery determination range is a single cell voltage of 10.6V-10.8V, and the high battery determination range is a single cell voltage >10.8V.

[0064] In this embodiment, specifically: in S222 and S312, the target voltage is the power limit point, and the bus voltage is maintained at the power limit point during driving. During this process, the battery power gradually decreases and the current limit of the MCU gradually decreases;

[0065] The gradual decrease in battery power means that the battery output power gradually decreases.

[0066] In this embodiment, specifically: the vehicle speed is gradually reduced, thereby avoiding the undervoltage protection triggered by low battery voltage due to rapid acceleration, thereby causing vehicle power interruption.

[0067] In this embodiment, specifically: in S222 and S312, the error calculation formula between the actual voltage and the target voltage is:

[0068] e=Vtarget-Vactual(1)

[0069] In formula (1), e is the voltage error, Vtarget is the target voltage, and Vactual is the actual measured voltage.

[0070] In this embodiment, specifically: in S222 and S312, the output regulation current calculation formula is:

[0071] Δl=Kp*e+Ki*∫ e dt(2)

[0072] In formula (2), Δl is the output current regulation amount, Kp is the proportional gain, e is the voltage error, and Ki is the integral gain.

[0073] In this embodiment, specifically: Δl is the amount by which the discharge current needs to be adjusted, which is calculated based on the voltage error, and is used to adjust the battery discharge current to maintain the target voltage; e reflects the deviation between the current voltage and the target value.

[0074] In this embodiment, specifically: Kp determines the response strength of the proportional term to the voltage error. The larger Kp is, the faster the proportional term Kp*e reacts to the error, thereby being able to quickly reduce the voltage deviation.

[0075] Among them, it needs to be further explained that: taking a value that is too large will cause system overshoot, that is, the voltage fluctuation exceeds the target value.

[0076] In this embodiment, specifically: Ki determines the intensity of the integral term on the voltage error accumulation, the integral term Ki*∫ e dt is used to eliminate steady-state errors, that is, small voltage deviations that exist for a long time. The larger Ki is, the stronger the integral effect is;

[0077] Among them, it is necessary to further explain that: if the value is too large, it will take longer for the system to reach a stable state and even cause oscillation.

[0078] In this embodiment, specifically: by combining experimental debugging with system modeling, by adjusting the values ​​of Kp and Ki, the PI controller can ensure system stability while quickly responding to voltage errors, thereby achieving the goal of maintaining the battery discharge voltage unchanged by adjusting the discharge current.

[0079] In this embodiment, specifically: in S3, the battery undervoltage value = the number of strings * the battery cell undervoltage value, and the power limit point is the battery undervoltage value + (the number of strings * 0.3).

[0080] Working principle: The electric tricycle is powered on, and the MCU is used to determine whether the battery type has a communication type. If the battery has no communication function, it is determined whether the current voltage value is greater than the power limit point. If it is determined to be greater than the power limit point, the battery is defined as high power, and the bus current is limited according to the current limit value set by the vehicle controller logic, and the electric tricycle runs normally. If it is determined to be less than the power limit point, it is determined whether the current voltage value is greater than the undervoltage point. If it is less than the undervoltage point, the battery is defined as low power, that is, undervoltage, and the electric tricycle cannot be started. If it is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated according to the error between the actual voltage and the target voltage, and the current value to maintain the target voltage is calculated for current limiting.

[0081] When the battery has a communication function, the battery undervoltage value and power limit point are calculated according to the number of battery strings. If it is determined to be less than the power limit point, determine whether the current voltage value is greater than the undervoltage point. If it is less than the undervoltage point, the battery is defined as low power, that is, undervoltage, and the electric tricycle cannot be started. If it is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated according to the error between the actual voltage and the target voltage, and the current value to maintain the target voltage is calculated for current limiting. If it is determined to be greater than the power limit point, determine whether the maximum continuous discharge current of the battery is greater than the MCU current limit value. If it is greater than the MCU current limit value, the battery is defined as To meet the power demand of the MCU, the current is limited according to the MCU current limit value, and the tram runs normally. When the current is less than the MCU current limit value, it is defined that the battery is low and cannot meet the power demand of the MCU. At this time, it is judged whether the current battery SOC is ≥10%. If the battery SOC is ≥10%, the current is limited according to the maximum continuous discharge current allowed by the battery. If the battery SOC is ≤10%, it is judged whether the current battery SOC is ≥3%. If the battery SOC is ≥3%, the current is limited according to 80% of the battery's allowable discharge current. If the battery SOC is ≤3%, the current is limited according to 50% of the battery's allowable discharge current.

[0082] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the utilization rate of battery discharge power for an electric tricycle, characterized in that: The following steps are involved: S1. Power on the electric tricycle and use the MCU to determine whether the battery type has the communication type. S2. When the battery has no communication function, determine whether the current voltage value is greater than the power limit point; S21: When it is determined that the power is greater than the power limit point, the battery is defined as high power, so that the bus current is limited according to the current limit value set by the vehicle controller logic, and the electric tricycle runs normally; S22: If it is determined that the current voltage value is less than the power limit point, it is determined whether the current voltage value is greater than the undervoltage point; S221: When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started; S222: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed. S3. When the battery has communication function, the battery undervoltage value and power limit point are calculated according to the number of battery strings; S31, when it is determined that the current voltage value is less than the power limit point, determining whether the current voltage value is greater than the undervoltage point; S311. When the voltage is less than the undervoltage point, the battery is defined as low power, i.e., undervoltage, and the electric tricycle cannot be started; S312: If the voltage is greater than the undervoltage point, the battery is defined as normal power. The proportional gain and integral gain are calculated based on the error between the actual voltage and the target voltage. The current value required to maintain the target voltage is calculated and current limiting is performed. S32: When it is determined that the current is greater than the power limit point, determine whether the maximum continuous discharge current of the battery is greater than the MCU current limit value; S321. When the current is greater than the MCU current limit value, it is defined that the battery can meet the power demand of the MCU, and the current is limited according to the MCU current limit value, and the electric vehicle runs normally; S322: If the current is less than the MCU current limit value, the battery is defined as low power and cannot meet the power demand of the MCU. At this time, it is determined whether the current battery SOC is ≥ 10%; When the battery SOC is ≥ 10%, the current is limited according to the maximum continuous discharge current allowed by the battery; When the battery SOC is ≤10%, determine whether the current battery SOC is ≥3%; When the battery SOC is ≥ 3%, the current is limited to 80% of the battery's allowable discharge current; When the battery SOC is ≤ 3%, the current is limited to 50% of the battery's allowable discharge current.

2. The method for improving battery discharge power utilization rate for an electric tricycle according to claim 1, characterized in that: The low battery judgment range is a single cell voltage of 10.4v-10.5v, the normal battery judgment range is a single cell voltage of 10.6v-10.8v, and the high battery judgment range is a single cell voltage >10.8v.

3. The method for improving battery discharge power utilization rate for an electric tricycle according to claim 1, characterized in that: In S222 and S312, the target voltage is the power limit point, and the bus voltage is maintained at the power limit point during driving. During this process, the battery power gradually decreases and the MCU current limit gradually decreases; The gradual decrease in battery power means that the battery output power gradually decreases.

4. The method for improving battery discharge power utilization rate for an electric tricycle according to claim 1, characterized in that: In S222 and S312, the error calculation formula between the actual voltage and the target voltage is: e=Vtarget-Vactual (1) In formula (1), e is the voltage error, Vtarget is the target voltage, and Vactual is the actual measured voltage.

5. The method for improving the utilization rate of battery discharge power for an electric tricycle according to claim 1, characterized in that: In S222 and S312, the output regulation current calculation formula is: Δl=Kp*e+Ki*∫ e dt(2) In formula (2), Δl is the output current regulation amount, Kp is the proportional gain, e is the voltage error, and Ki is the integral gain.

6. The method for improving battery discharge power utilization rate for an electric tricycle according to claim 1, characterized in that: In S3, the battery undervoltage value = the number of strings * the battery cell undervoltage value, and the power limit point is the battery undervoltage value + (number of strings * 0.3).

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