A control method based on temperature monitoring to maximize the cumulative charge transfer

Abstract

The present invention relates to the field of electric vehicle charging technology, and in particular to a control method based on temperature monitoring with the maximum cumulative charge transmission as the goal, which adjusts to the maximum output current in real time within the allowed range of demand; during the charging process, the ambient temperature and current at that moment are recorded; if the temperature difference between T1 and T2, T3 and T4 is less than the threshold a, the power supply terminal A continues to output current; based on the ambient temperature and current, there will be a certain temperature rise rate, if the temperature rise rate is less than the threshold b, then detect whether T1, T2, T3 and T4 are less than the threshold c, if T1, T2, T3 and T4 are all less than the threshold c, then the power supply terminal A continues to output. Compared with the prior art, the control method based on temperature monitoring with the maximum cumulative charge transmission as the goal of the present invention can achieve the shortest time for charging the same amount of electricity under the premise of taking into account the safety and life of the charging gun, that is, achieve the effect of fast charging.

Description

[Technical field]

[0001] The present invention relates to the technical field of electric vehicle charging, and in particular to a control method based on temperature monitoring with the goal of transmitting a maximum accumulated charge amount. [Background technology]

[0002] Currently, the maximum rated current value of electric vehicle charging guns is determined based on the cable cross-sectional area, such as 70mm 2 The cable can pass 250A current. Most DC charging guns on the market are like this, with a maximum current of 250A, regardless of the ambient temperature and the quality and aging of the cable itself.

[0003] Such a charging gun is very heavy. If a larger current is passed, a thicker wire diameter will be required, which will be even heavier. Therefore, a liquid cooling gun has recently appeared on the market, 35mm 2 The cable is liquid cooled to remove heat and can carry 600A of current.

[0004] Based on the above, we can see that the heat generated by the current in the cable must be controlled and cannot exceed the maximum temperature threshold. If it is in a state of exceeding the maximum temperature threshold for a long time, it is easy to have safety hazards, affecting the service life of the cable and is not conducive to charging safety. [Summary of the invention]

[0005] In order to overcome the above problems, the present invention proposes a control method based on temperature monitoring and aiming at maximizing the cumulative charge transfer, which can effectively solve the above problems.

[0006] The present invention provides a technical solution to solve the above technical problems: providing a control method based on temperature monitoring with the maximum cumulative charge transmission as the goal, comprising the following steps:

[0007] Step S1, connecting the charging structure and preparing for charging;

[0008] Step S2, the power supply terminal A starts to output current, and adjusts to the maximum output current in real time within the allowed range of demand;

[0009] Step S3, during the charging process, recording the ambient temperature Ta at the maximum output current of the power supply terminal A and the current Io passing through the charging cable C;

[0010] Step S4, detecting a temperature difference 1 between the temperature T1 measured by the first temperature sensor and the temperature T2 measured by the second temperature sensor, detecting a temperature difference 2 between the temperature T3 measured by the third temperature sensor and the temperature T4 measured by the fourth temperature sensor, and comparing whether the temperature difference 1 and the temperature difference 2 are less than a threshold value a respectively;

[0011] Step S5, if the temperature difference 1 and the temperature difference 2 are both less than the threshold a, the power supply terminal A continues to output current;

[0012] Step S6, based on the ambient temperature Ta and the current, there is a certain temperature rise rate, and it is determined whether the temperature rise rate is less than a threshold value b;

[0013] Step S7, if the temperature rise rate is less than the threshold value b, then detect whether the temperature T1, temperature T2, temperature T3 and temperature T4 are less than the threshold value c. If the temperature T1, temperature T2, temperature T3 and temperature T4 are all less than the threshold value c, the power supply end A continues to output.

[0014] Preferably, in step S1, the charging structure includes a power supply terminal A, a load terminal B and a charging cable C, and two ends of the charging cable C are connected to the power supply terminal A and the load terminal B respectively.

[0015] Preferably, a first temperature sensor and a second temperature sensor are mounted at the connection between the power supply end A and the charging cable C, a third temperature sensor and a fourth temperature sensor are mounted at the connection between the load end B and the charging cable C, and a fifth temperature sensor is mounted on the outer casing of the power supply end A.

[0016] Preferably, in step S4, if at least one of the temperature difference 1 and the temperature difference 2 is greater than or equal to the threshold a, the power supply terminal A first reduces the current, and if the purpose of reducing the temperature cannot be achieved, the output is stopped.

[0017] Preferably, in step S6, if the temperature rise rate is greater than or equal to the threshold value b, the power supply terminal A reduces the current, determines the temperature rise rate based on the ambient temperature Ta and the current again, and determines whether the temperature rise rate is less than the threshold value b.

[0018] Preferably, in step S6, the current is reduced in advance according to a formula and data calibration from multiple experiments in advance, and the temperature rise rate is controlled not to exceed a threshold value b.

[0019] Preferably, the formula is:

[0020] Io2=x*K+y(Tm-Ta)

[0021] In the formula, the coefficient coefficient Io is the current passing through the charging cable C, Tm is the temperature of the conductive copper wire, K is the temperature rise of the conductive copper wire, and Ta is the ambient temperature;

[0022] Where ρ resistivity is the resistivity of the conductor; S is the cross-sectional area of ​​the conductor; ρ density is the density of the conductor; c is the specific heat capacity of the conductor; d1 is the inner diameter of the insulation skin; d2 is the outer diameter of the insulation skin; λ is the heat transfer coefficient of the insulation skin; h is the convection heat transfer coefficient between the insulation skin and the air.

[0023] Preferably, in step S7, if the maximum value among the temperature T1, the temperature T2, the temperature T3 and the temperature T4 is greater than or equal to the threshold value c, the power supply terminal A stops outputting.

[0024] Preferably, in step S7, the maximum current operating point close to the upper temperature limit of the charging cable C is found and dynamically maintained not to exceed a threshold value c.

[0025] Preferably, the threshold a is in the range of 5-15°C, the threshold b is in the range of 10-80K / min, and the threshold c is in the range of 90-105°C.

[0026] Compared with the prior art, the control method based on temperature monitoring with the goal of maximum cumulative charge transmission of the present invention is based on cable temperature monitoring and real-time adjustment of current, which can achieve maximum charge transmission under specific conditions, that is, the integration of current I over time, to achieve the maximization of ∑i*t; the maximum charge transmission technology can achieve the shortest time for charging the same amount of electricity while taking into account the safety and life of the charging gun, that is, achieve the effect of fast charging; it is suitable for maximum charge transmission control of DC charging guns, AC charging guns, ordinary charging guns, liquid-cooled charging guns, and other conductive cables.

Brief Description of the Drawings

[0027] Figure 1 A schematic diagram of a charging structure of a control method for transmitting a maximum accumulated charge based on temperature monitoring according to the present invention;

[0028] Figure 2 It is a flow chart of a control method based on temperature monitoring with the goal of transmitting the maximum accumulated charge amount according to the present invention;

[0029] Figure 3 The figure is a current and temperature curve diagram of the control method of the present invention based on temperature monitoring with the goal of transferring the maximum accumulated charge. [Specific implementation method]

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation examples. 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.

[0031] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0032] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] See also Figures 1 to 3 The control method of the present invention based on temperature monitoring and aiming at transmitting the maximum accumulated charge is used for charging control, and comprises the following steps:

[0034] Step S1, connect the charging structure and prepare for charging.

[0035] In step S1, the charging structure includes a power supply terminal A, a load terminal B and a charging cable C, and two ends of the charging cable C are connected to the power supply terminal A and the load terminal B respectively.

[0036] In step S1, a first temperature sensor and a second temperature sensor are mounted at the connection between the power supply terminal A and the charging cable C, a third temperature sensor and a fourth temperature sensor are mounted at the connection between the load terminal B and the charging cable C, and a fifth temperature sensor is mounted on the housing of the power supply terminal A.

[0037] In step S1, the first temperature sensor and the second temperature sensor are used to measure the temperatures T1 and T2 at the connection between the power supply end A and the charging cable C, respectively; the third temperature sensor and the fourth temperature sensor are used to measure the temperatures T3 and T4 at the connection between the load end B and the charging cable C, respectively; and the fifth temperature sensor is used to measure the ambient temperature Ta.

[0038] In the step S1, the charging cable C includes an insulating sheath and a conductive copper wire, wherein the insulating sheath covers the outside of the conductive copper wire.

[0039] The power supply end A is an electric vehicle charging pile, the load end B is an electric vehicle, and the charging cable C is a charging gun.

[0040] Step S2: the power supply terminal A starts to output current, and adjusts the current to the maximum output current in real time within the permitted range of demand.

[0041] In step S2, the current output is maximized within the required current range to achieve the fastest speed to reach the upper temperature threshold.

[0042] Step S3, during the charging process, record the ambient temperature Ta at the maximum output current of the power supply terminal A and the current Io passing through the charging cable C. The current Io is the only current in the charging process, and the current referred to in this application is the current Io.

[0043] Step S4, detecting the temperature difference one between the temperature T1 measured by the first temperature sensor and the temperature T2 measured by the second temperature sensor, detecting the temperature difference two between the temperature T3 measured by the third temperature sensor and the temperature T4 measured by the fourth temperature sensor, and comparing whether the temperature difference one and the temperature difference two are less than the threshold a respectively.

[0044] In step S4, if at least one of the temperature difference 1 and the temperature difference 2 is greater than or equal to the threshold a, the power supply terminal A first reduces the current. If the purpose of reducing the temperature cannot be achieved, the output is stopped.

[0045] In step S4, the threshold value a is in the range of 5 to 15°C.

[0046] Step S5: if the temperature difference 1 and the temperature difference 2 are both smaller than the threshold a, the power supply terminal A continues to output current.

[0047] Step S6: Based on the ambient temperature Ta and the current, there is a certain temperature rise rate of the conductive copper wire, and it is determined whether the temperature rise rate is less than a threshold value b.

[0048] In step S6, if the temperature rise rate is greater than or equal to the threshold value b, the power supply terminal A reduces the current, and again based on the ambient temperature Ta and the current, there will be a certain temperature rise rate, and it is determined whether the temperature rise rate is less than the threshold value b.

[0049] In step S6, the relationship between the current Io passing through the charging cable C, the temperature Tm of the conductive copper wire and its temperature rise K and the ambient temperature Ta is:

[0050] Io2=x*K+y(Tm-Ta)

[0051] In the formula, the coefficient coefficient

[0052] Where ρ resistivity is the resistivity of the conductor; S is the cross-sectional area of ​​the conductor; ρ density is the density of the conductor; c is the specific heat capacity of the conductor; d1 is the inner diameter of the insulation skin; d2 is the outer diameter of the insulation skin; λ is the heat transfer coefficient of the insulation skin; h is the convection heat transfer coefficient between the insulation skin and the air.

[0053] Considering that the temperature of the temperature sensor lags behind the actual temperature for a period of time, according to the above formula and the data calibration of multiple experiments in advance, the current is reduced in advance to control the temperature rise rate not to exceed the threshold b.

[0054] The threshold value b ranges from 10 to 80 K / minute, that is, 10 to 80 K / min.

[0055] The temperature rise rate is the temperature rise rate of the conductive copper wire.

[0056] Step S7, if the temperature rise rate of the conductive copper wire is less than the threshold value b, then detect whether the temperature T1, temperature T2, temperature T3 and temperature T4 are less than the threshold value c. If the temperature T1, temperature T2, temperature T3 and temperature T4 are all less than the threshold value c, the power supply end A continues to output.

[0057] In the step S7, if the maximum value among the temperature T1, the temperature T2, the temperature T3 and the temperature T4 is greater than or equal to the threshold value c, the power supply terminal A stops outputting.

[0058] In the step S7, the threshold value c is in the range of 90 to 105°C.

[0059] In step S7, the maximum current operating point close to the upper temperature limit of the charging cable C is found and dynamically kept not exceeding the threshold value c. If the temperature exceeds the limit, the current can be reduced in real time to rebalance the temperature.

[0060] In step S7, the method of finding the maximum current operating point close to the upper temperature limit of the charging cable C and dynamically maintaining it not exceeding the threshold value c can be calibrated through a set of tests. The maximum current under different ambient temperatures Ta is different; the software of the charging pile charging control board is dynamically adjusted in real time through PID (proportion, integration, differentiation), and the example test calibration data is shown in the following table

[0061]

[0062]

[0063] Temperature rise rate test calibration

[0064] Ambient temperature Ta Test current Temperature rise rate b -20 300A 30k / min -10 300A 30k / min 0 300A 30k / min 10 300A 31k / min 20 300A 31k / min 30 300A 32k / min 40 300A 32k / min -20 400A 42k / min -10 400A 42k / min 0 400A 42k / min 10 400A 43k / min 20 400A 43k / min 30 400A 45k / min 40 400A 45k / min -20 500A 57k / min … … …

[0065] Finally, the charge Q = I*t (ampere-hours) is maximized, that is, Figure 3 The area enclosed by the medium current curve is the largest.

[0066] Compared with the prior art, the control method based on temperature monitoring with the goal of maximum cumulative charge transmission of the present invention is based on cable temperature monitoring and real-time adjustment of current, which can achieve maximum charge transmission under specific conditions, that is, the integration of current I over time, to achieve the maximization of ∑i*t; the maximum charge transmission technology can achieve the shortest time for charging the same amount of electricity while taking into account the safety and life of the charging gun, that is, achieve the effect of fast charging; it is suitable for maximum charge transmission control of DC charging guns, AC charging guns, ordinary charging guns, liquid-cooled charging guns, and other conductive cables.

[0067] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. A control method based on temperature monitoring with the goal of transferring the maximum accumulated charge, characterized in that: The steps include: Step S1, connecting the charging structure to prepare for charging; in step S1, the charging structure includes a power supply terminal A, a load terminal B and a charging cable C, and both ends of the charging cable C are respectively connected to the power supply terminal A and the load terminal B; a first temperature sensor and a second temperature sensor are mounted at the connection between the power supply terminal A and the charging cable C, a third temperature sensor and a fourth temperature sensor are mounted at the connection between the load terminal B and the charging cable C, and a fifth temperature sensor is mounted on the housing of the power supply terminal A; Step S2, the power supply terminal A starts to output current, and adjusts to the maximum output current in real time within the allowed range of demand; Step S3, during the charging process, recording the ambient temperature Ta at the maximum output current of the power supply terminal A and the current Io passing through the charging cable C; Step S4, detecting a temperature difference 1 between the temperature T1 measured by the first temperature sensor and the temperature T2 measured by the second temperature sensor, detecting a temperature difference 2 between the temperature T3 measured by the third temperature sensor and the temperature T4 measured by the fourth temperature sensor, and comparing whether the temperature difference 1 and the temperature difference 2 are less than a threshold value a respectively; Step S5, if the temperature difference 1 and the temperature difference 2 are both less than the threshold a, the power supply terminal A continues to output current; Step S6, based on the ambient temperature Ta and the current, there is a certain temperature rise rate, and it is determined whether the temperature rise rate is less than a threshold value b; Step S7, if the temperature rise rate is less than the threshold value b, then detect whether the temperature T1, temperature T2, temperature T3 and temperature T4 are less than the threshold value c. If the temperature T1, temperature T2, temperature T3 and temperature T4 are all less than the threshold value c, the power supply end A continues to output.

2. The control method according to claim 1, wherein the control method is based on temperature monitoring and aims at transferring the maximum accumulated charge. In step S4, if at least one of the temperature difference 1 and the temperature difference 2 is greater than or equal to the threshold a, the power supply terminal A first reduces the current. If the purpose of reducing the temperature cannot be achieved, the output is stopped.

3. The control method according to claim 1, wherein the control method is based on temperature monitoring and aims at transferring the maximum accumulated charge. In step S6, if the temperature rise rate is greater than or equal to the threshold value b, the power supply terminal A reduces the current, and determines the temperature rise rate based on the ambient temperature Ta and the current again to determine whether the temperature rise rate is less than the threshold value b.

4. The control method according to claim 3, wherein the control method is based on temperature monitoring and aims at transferring the maximum accumulated charge. In step S6, according to the formula and the data calibration of multiple experiments in advance, the current is reduced in advance to control the temperature rise rate not to exceed the threshold value b.

5. The control method according to claim 4, wherein the control method is based on temperature monitoring and aims at transferring the maximum accumulated charge. The formula is: Io²=x*K + y(Tm-Ta) In the formula, coefficient x= , coefficient y = ; Io is the current passing through the charging cable C, Tm is the temperature of the conductive copper wire, K is the temperature rise of the conductive copper wire, and Ta is the ambient temperature; Where ρ resistivity is the resistivity of the conductor; S is the cross-sectional area of ​​the conductor; ρ density is the density of the conductor; c is the specific heat capacity of the conductor; d1 is the inner diameter of the insulation skin; d2 is the outer diameter of the insulation skin; λ is the heat transfer coefficient of the insulation skin; h is the convection heat transfer coefficient between the insulation skin and the air.

6. The control method based on temperature monitoring and aiming at transferring the maximum accumulated charge according to claim 1, characterized in that: In the step S7, if the maximum value among the temperature T1, the temperature T2, the temperature T3 and the temperature T4 is greater than or equal to the threshold value c, the power supply terminal A stops outputting.

7. The control method according to claim 1, wherein the control method aims at transferring the maximum accumulated charge based on temperature monitoring. In step S7, the maximum current operating point close to the upper temperature limit of the charging cable C is found and dynamically maintained not to exceed the threshold value c.

8. The control method according to claim 1, wherein the control method is based on temperature monitoring and aims at transferring the maximum accumulated charge. The threshold a ranges from 5 to 15°C, the threshold b ranges from 10 to 80 K / min, and the threshold c ranges from 90 to 105°C.

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