Method and system for detecting the state of a charging system of an electric vehicle

Abstract

The present invention provides a method and system for detecting the state of a charging system of an electric vehicle. The method comprises the following steps: a) obtaining the control variable value and signal measurement value of the charging system of the electric vehicle at the current moment; b) calculating the predicted system state of the charging system at the current moment according to the control variable value at the current moment and the system state of the charging system at the previous moment, wherein the system state of the charging system at the initial moment is preset; c) calculating the measurement deviation of the charging system at the current moment according to the signal measurement value at the current moment and the predicted system state at the current moment; and d) calculating the system state of the charging system at the current moment according to the system state at the previous moment, the predicted system state at the current moment and the measurement deviation at the current moment. The present invention also provides a corresponding system.

Description

Technical Field

[0001] The present invention relates to the field of electric vehicles, and in particular to a method and a system for detecting the state of a charging system of an electric vehicle. Background Art

[0002] In recent years, with the development of the electric vehicle industry, the charging system of electric vehicles has also been widely used. It is particularly necessary to be able to quickly judge the system status based on the signal in the charging system of the electric vehicle, so as to be able to quickly respond to the system status changes reflected by the signal.

[0003] For the above-mentioned charging system, it is necessary to instantly determine whether various signals have reached specific limits to determine the system status, while also avoiding misjudgment due to noise and interference in the signal. The prior art detects the system status by performing algorithms such as mean operation, bubble sort operation or median operation on the ADC sampling value of the signal, or by hardware rectifying the signal before sampling. However, these methods have problems such as lengthy calculation process, slow response to signal changes, poor anti-interference ability, and poor sensitivity to short signals, which seriously affect the detection accuracy, and the response speed is difficult to meet the increasing user needs.

[0004] Therefore, there is an urgent need for a new technology with fast response speed, high detection accuracy and strong anti-interference ability to detect the charging system status of electric vehicles. Summary of the invention

[0005] The present invention aims to overcome the above and / or other problems in the prior art. The method and system for detecting the state of the charging system of an electric vehicle provided by the present invention can detect the signal quickly and accurately, and is not easily affected by interference and signal noise, thereby achieving a rapid response to signal changes.

[0006] According to a first aspect of the present invention, there is provided a method for detecting the state of a charging system of an electric vehicle, comprising the following steps: a) obtaining control variable values ​​and signal measurement values ​​of the charging system of the electric vehicle at a current moment; b) calculating a predicted system state of the charging system at the current moment based on the control variable values ​​at the current moment and the system state of the charging system at a previous moment, wherein the system state of the charging system at an initial moment is preset; c) calculating a measurement deviation of the charging system at the current moment based on the signal measurement values ​​at the current moment and the predicted system state at the current moment; and d) calculating the system state of the charging system at the current moment based on the system state at the previous moment, the predicted system state at the current moment and the measurement deviation at the current moment.

[0007] According to a second aspect of the present invention, a system for detecting the state of a charging system of an electric vehicle is provided, the system comprising a sensing unit and a processing unit. The sensing unit is configured to measure the control variable value and the signal measurement value of the charging system of the electric vehicle. The processing unit is configured to: a) obtain the control variable value and the signal measurement value of the charging system at the current moment from the sensing unit; b) calculate the predicted system state of the charging system at the current moment according to the control variable value at the current moment and the system state of the charging system at the previous moment, wherein the system state of the charging system at the initial moment is preset; c) calculate the measurement deviation of the charging system at the current moment according to the signal measurement value at the current moment and the predicted system state at the current moment; and d) calculate the system state of the charging system at the current moment according to the system state at the previous moment, the predicted system state at the current moment, and the measurement deviation at the current moment.

[0008] The above detection method and detection system of the present invention use the signal itself (i.e., signal measurement value) and various interference factors (i.e., control variable values) in the charging system at the same time, which fully considers the influence of various interference factors on the system state. In addition, by using the system state at the previous moment to predict and calculate the system state at the current moment, the detection method and detection system of the present invention use an autoregressive algorithm to ensure the rapid convergence of the detection results, which greatly improves the response speed and accuracy of the detection.

[0009] Preferably, in the detection method and detection system of the present invention, the relationship between the control variable value and the predicted system state at the current moment can be set according to the configuration of the charging system. Thus, the control variable value as an interference factor can be associated with the influence of the system state of the charging system.

[0010] Preferably, steps a) to d) above can be performed repeatedly and cyclically.

[0011] The signal measurement value may be a measurement value of a control pilot function signal (CP signal). The sensing unit may include a peak response vehicle-side circuit for acquiring the CP signal. The CP signal may be used to monitor the function of the interaction between the electric vehicle and its charging system, thereby detecting the state of the charging system based on the CP signal.

[0012] The signal measurement value may also be a measurement value of a leakage current signal. The sensing unit may include a mutual inductor and an operational amplifier for acquiring the leakage current signal. The leakage current signal may be used to determine whether the charging system is in a leakage state.

[0013] According to a third aspect of the present invention, there is further provided a computer-readable storage medium on which instructions are stored, and when the instructions are executed, the detection method according to the present invention as described above is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention may be better understood by describing exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0015] Figure 1 A flow chart showing a method for detecting a charging system status of an electric vehicle according to the present invention; and

[0016] Figure 2 A block diagram of a system for detecting the state of a charging system of an electric vehicle according to the present invention is shown. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present application. However, the present application can obviously be implemented in a variety of other ways different from this description. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the spirit of the present application. Therefore, the scope of protection of the present application should not be limited by the content of this specific embodiment.

[0018] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meaning understood by persons with ordinary skills in the technical field to which the present application belongs. The words "first", "second" and similar words used in the specification and claims of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "one" or "a" do not indicate a quantitative limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprises" cover the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects.

[0019] According to an embodiment of the present invention, a method for detecting the state of a charging system of an electric vehicle is provided.

[0020] refer to Figure 1 , which shows a method 100 for detecting the state of a charging system of an electric vehicle according to the present invention. The method 100 may include steps 110 to 140.

[0021] like Figure 1As shown, in step 110, the control variable value C and the signal measurement value Z of the charging system of the electric vehicle at the current time t are obtained. The signal measurement value C is the measurement value of the signal directly related to the system state of the charging system, and the control variable value Z is the measurement value of the control variable (i.e., the interference factor) that affects the system state of the charging system. In an embodiment, the measurement value of the signal Z or the control variable C sampled in each time range can be averaged in units of a certain time range, and the result can be used as a measurement value of the signal Z or the control variable C.

[0022] In step 120, the predicted system state P(t) of the charging system at the current time t is calculated based on the control variable value C(t) at the current time t and the system state X(t-1) of the charging system at the previous time (t-1). The system state at the initial time can be preset according to the configuration of the charging system. The control variable C can be various interference factors from the charging system that can affect the system state.

[0023] In step 130, the measurement deviation J(t) of the charging system at the current time t is calculated based on the signal measurement value Z(t) at the current time t and the predicted system state P(t) at the current time t. The measurement deviation is used to reflect the deviation in the signal measurement process.

[0024] In step 140, the system state X(t-1) of the charging system at the current time t is calculated based on the system state X(t-1) at the previous time (t-1), the predicted system state P(t) at the current time t, and the measured deviation J(t) at the current time t. Thus, an autoregressive algorithm for determining the system state X(t) at the current time t is formed.

[0025] When predicting the system state P(t) at the current time t, the above detection method compensates for the influence of various interference factors (for example, ambient temperature, charging current, etc.) on the system state by introducing the control variable value C(t), avoiding misjudgment due to deviations in the measurement process and improving the accuracy of detection; at the same time, the deviation between the actual signal measurement value Z(t) and the predicted system state P(t) at the current time t is used to compensate for the deviation generated in the signal measurement process (for example, due to noise, etc.), thereby further improving the anti-interference ability of the detection. The autoregressive algorithm in the above detection method combines the system state X(t-1) at the previous time (t-1) to calculate the system state X(t) at the current time t, so that the calculation has good convergence, thereby being able to quickly obtain the system state X(t) at the current time t from the measurement values ​​C(t) and Z(t) at the current time t, that is, achieving a rapid response to signal changes.

[0026] According to an embodiment of the present invention, the above steps 110 to 140 may be repeatedly performed cyclically, such as Figure 1 The execution cycle (e.g., 5 milliseconds) can also be set as needed, that is, the measurement value within every 5 milliseconds is used as a measurement value (as described in step 110), and steps 110 to 140 are executed to obtain the system state X(t) at the current time t, thereby the system state X(t) at the current time t can be timely understood as needed.

[0027] Optionally, before executing step 110 , the relationship between the control variable value C and the predicted system state P(t) at the current time t may be set according to the configuration of the charging system.

[0028] As described above, the control variable C may be various interference factors from the charging system. For example, during the operation of the charging system, the system temperature may rise due to system heating, or the system heat dissipation characteristics may be affected due to changes in ambient temperature. These temperature changes may further affect the measured signal value Z in a certain regularity, and further affect the judgment of the system state X(t) based on the signal value Z. For another example, during the charging operation of the charging system, the system characteristics may change accordingly due to the large current during charging. Therefore, for any given charging system configuration, the corresponding control variable C (such as the system temperature, ambient temperature, charging current, etc. as described above) can be pre-selected and a model Y (e.g., an empirical model) of each control variable C and its influence on the system state can be constructed. For example, the model Y can be in the form of a lookup table, in which the data in the table are the optimal calibration values ​​obtained based on actual tests.

[0029] In an embodiment, when executing step 120, the control variable value C(t) at the current time t can be substituted into the corresponding model Y (for example, by looking up a table) to obtain the influence value Y(C(t)) of the control variable value C(t) at the current time t on the predicted system state P(t) at the current time t, thereby reflecting the influence of the control variable in the predicted system state P(t).

[0030] An example of a method for detecting the state of a charging system of an electric vehicle according to the present invention is listed below, wherein the control variable value C and the signal measurement value Z are sampled at a sampling frequency of 1 kHz, and the sampling value every 5 milliseconds is used as a group of data, that is, the system state is detected at intervals of 5 milliseconds.

[0031] For the current time t, the control variable value is C(t). The predicted system state P(t) at time t can be calculated according to formula (1):

[0032] P(t)= aY(C(t))+bB+ cX(t-1); Formula (1)

[0033] Wherein Y(C(t)) is the influence value obtained by bringing the control variable value C(t) at time t into the corresponding model (for example, by looking up a table), B is the deviation constant introduced in the calculation process, X(t-1) is the system state at time (t-1) (i.e., the previous time), a, b, and c are setting parameters, and b can be proportional to c after being calibrated according to the configuration of the charging system.

[0034] Then, the measurement deviation J(t) at time t can be calculated according to formula (2):

[0035] J(t)=(1 / n)Z(t)-(m / n)P(t); Formula (2)

[0036] Where Z(t) is the signal measurement value at time t, m is a parameter of the measurement system, and n is a parameter that is proportional to m after calibration based on the configuration of the charging system.

[0037] Next, the system state X(t) at time t can be calculated according to formula (3):

[0038] X(t)=P(t)+kJ(t); Formula (3)

[0039] Where k represents the percentage of measurement deviation adopted. For example, the k value can be calculated by performing a covariance operation on P(t) and X(t-1): k = Cov(P(t), X(t-1)) / (Cov(P(t), X(t-1))+J(t)). The k value can be quickly obtained by reducing the time required for the covariance operation at time t by using the process value saved in the covariance operation at time (t-1).

[0040] Finally, substituting the value of k into formula (3) we can obtain the system state X(t) at time t.

[0041] In one embodiment, the signal measurement value Z may be, for example, a measurement value of a control pilot function signal (CP signal). The CP signal is a handshake signal between an electric vehicle and a charging system of the electric vehicle, and can be used to monitor the interaction between the electric vehicle and the charging system of the electric vehicle, so the state of the charging system can be detected according to the CP signal. When the CP signal is used as a signal measurement value, problems such as plug-in recognition failure and abnormal charging interruption in the charging system can be avoided. In an embodiment, a peak response vehicle-side circuit can be used to obtain the CP signal.

[0042] In another embodiment, the signal measurement value Z may also be, for example, the measurement value of a leakage current signal. In a charging system, current leakage may be caused by insulation damage or other reasons, and when the leakage current reaches a certain value, it is considered that the system is in a leakage state, and a leakage response needs to be triggered immediately. When the leakage current signal is used as the signal measurement value, it is possible to quickly and accurately detect that the system is in a leakage state, thereby triggering a leakage response in time and avoiding false triggering. In an embodiment, a mutual inductor and an operational amplifier may be used to obtain the leakage current signal.

[0043] In addition, the above-mentioned detection method according to the present invention can be implemented by executing computer instructions by a processor, and the instructions can be stored in a computer-readable storage medium. The computer-readable storage medium may include a hard disk drive, a floppy disk drive, a compact disk read / write (CD-R / W) drive, a digital versatile disk (DVD) drive, a flash drive and / or a solid-state storage device, etc.

[0044] According to an embodiment of the present invention, a system 200 for detecting the state of a charging system of an electric vehicle is also provided. Figure 2 As shown, the system 200 includes a sensing unit 210 and a processing unit 220 .

[0045] The sensing unit 210 may be configured to measure a control variable value C and a signal measurement value Z of a charging system of an electric vehicle.

[0046] The processing unit 220 may be configured to: a) obtain the control variable value C(t) and the signal measurement value Z(t) of the charging system at the current time t from the sensing unit 210; b) calculate the predicted system state P(t) of the charging system at the current time t according to the control variable value C(t) at the current time t and the system state X(t-1) of the charging system at the previous time (t-1), wherein the system state X(0) of the charging system at the initial time is preset; c) calculate the measurement deviation J(t) of the charging system at the current time t according to the signal measurement value Z(t) at the current time t and the predicted system state P(t) at the current time t; and d) calculate the system state X(t) of the charging system at the current time t according to the system state X(t-1) at the previous time (t-1), the predicted system state P(t) at the current time t, and the measurement deviation J(t) at the current time t.

[0047] According to an embodiment of the present invention, the processing unit 220 may be configured to execute a) to d) repeatedly and cyclically.

[0048] Alternatively, the relationship of the control variable value C to the predicted system state P(t) at the current time t may be set according to the configuration of the charging system.

[0049] In one embodiment, the signal measurement value Z may be, for example, a measurement value of a CP signal. The sensing unit 210 may include a peak response vehicle-side circuit for acquiring the CP signal.

[0050] In another embodiment, the signal measurement value Z may also be, for example, a measurement value of a leakage current signal. The sensing unit 210 may include a mutual inductor and an operational amplifier, for acquiring the leakage current signal.

[0051] The detection system 200 can implement the method for detecting the state of the charging system of an electric vehicle according to the present invention as described above. Many design concepts and details applicable to the detection method of the present invention are also applicable to the system 200, and the same beneficial technical effects can be obtained, which will not be repeated here.

[0052] Various aspects of the present invention have been described above through some exemplary embodiments. However, it should be understood that various modifications may be made to the above exemplary embodiments without departing from the spirit and scope of the present invention. For example, if the described techniques are performed in a different order and / or if the components in the described system, architecture, device or circuit are combined in different ways and / or replaced or supplemented by other components or their equivalents, suitable results may be achieved, and accordingly, these modified other embodiments also fall within the scope of protection of the claims.

Claims

1. A method for detecting the state of a charging system of an electric vehicle, comprising the following steps: a) measuring the control variable value and the signal measurement value of the charging system of the electric vehicle, and obtaining the control variable value C(t) and the signal measurement value Z(t) of the charging system of the electric vehicle at the current moment; b) calculating a predicted system state P(t) of the charging system at the current moment according to the control variable value C(t) at the current moment and the system state X(t-1) of the charging system at the previous moment, wherein the system state of the charging system at the initial moment is preset; c) calculating a measurement deviation J(t) of the charging system at the current moment according to the signal measurement value Z(t) at the current moment and the predicted system state P(t) at the current moment; as well as d) Calculating the system state X(t) of the charging system at the current moment based on the system state X(t-1) at the previous moment, the predicted system state P(t) at the current moment, and the measured deviation J(t) at the current moment: X(t)=P(t)+kJ(t), where k is calculated by covariance operation: k=Cov(P(t),X(t-1)) / (Cov(P(t),X(t-1))+J(t)).

2. The method according to claim 1, characterized in that Before executing step a), the method further comprises: setting the relationship between the control variable value C(t) and the predicted system state at the current moment according to the configuration of the charging system.

3. The method according to claim 1, characterized in that Steps a) to d) are performed repeatedly in a cycle.

4. The method according to any one of claims 1 to 3, characterized in that The signal measurement value is a measurement value of the CP signal.

5. The method according to claim 4, characterized in that The CP signal is obtained using a peak response vehicle-side circuit.

6. The method according to any one of claims 1 to 3, characterized in that The signal measurement value is a measurement value of a leakage current signal.

7. The method according to claim 6, characterized in that A transformer and an operational amplifier are used to obtain the leakage current signal.

8. A system for detecting the state of a charging system of an electric vehicle, comprising: a sensing unit configured to measure a control variable value and a signal measurement value of a charging system of the electric vehicle; The processing unit is configured as follows: a) acquiring a control variable value C(t) and a signal measurement value Z(t) of the charging system at a current moment from the sensing unit; b) calculating a predicted system state P(t) of the charging system at the current moment according to the control variable value C(t) at the current moment and the system state X(t-1) of the charging system at the previous moment, wherein the system state of the charging system at the initial moment is preset; c) calculating a measurement deviation J(t) of the charging system at the current moment according to the signal measurement value Z(t) at the current moment and the predicted system state P(t) at the current moment; as well as d) Calculating the system state X(t) of the charging system at the current moment based on the system state X(t-1) at the previous moment, the predicted system state P(t) at the current moment, and the measured deviation J(t) at the current moment: X(t)=P(t)+kJ(t), where k is calculated by covariance operation: k=Cov(P(t),X(t-1)) / (Cov(P(t),X(t-1))+J(t)).

9. The system according to claim 8, characterized in that The relationship of the control variable value C(t) to the predicted system state at the current moment is set according to the configuration of the charging system.

10. The system according to claim 8, characterized in that The processing unit is configured to execute a) to d) in a repeated cycle.

11. The system according to any one of claims 8 to 10, characterized in that: The signal measurement value is a measurement value of the CP signal, Wherein, the sensing unit includes a peak response vehicle-side circuit for acquiring the CP signal.

12. The system according to any one of claims 8 to 10, characterized in that: The signal measurement value is a measurement value of a leakage current signal, Wherein, the sensing unit includes a mutual inductor and an operational amplifier, which are used to obtain the leakage current signal.

13. A computer-readable storage medium having instructions stored thereon, which implement the method according to any one of claims 1 to 7 when the instructions are executed.

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