Electrochemical cell system for a vehicle

Abstract

The application proposes an electrochemical cell system for a vehicle, comprising an electrochemical cell (11) adapted to supply electrical energy to a load (2), an alternating current generator (13) adapted to generate an alternating current, and an alternating current transformer (14), wherein a primary winding (141) of the alternating current transformer (14) is connected to the alternating current generator (13), and a secondary winding (142) of the alternating current transformer (14) is connected to an output of the electrochemical cell (11) in series with the electrochemical cell (11) and the load (2), so that the alternating current is injected from the primary winding (141) into the electrochemical cell (11) via the secondary winding (142) by electromagnetic induction. By means of the application, the electrochemical cell can be injected with an alternating current in a wider frequency range.

Description

Technical Field

[0001] This application relates to the field of electrochemical battery technology, and more specifically to an electrochemical battery system for a vehicle. Background Technology

[0002] Electrochemical batteries, due to their environmental friendliness and high energy conversion efficiency, have become a promising power source in the field of new energy vehicles. However, their complex internal electrochemical reaction processes are susceptible to factors such as fluctuations in operating conditions and component aging. During operation, electrochemical batteries may experience malfunctions such as membrane electrode dehydration or abnormal gas diffusion, which directly affect system lifespan and safety. Therefore, online real-time monitoring of the internal state of electrochemical batteries is a key technological requirement for ensuring reliable vehicle operation.

[0003] Electrochemical impedance spectroscopy (EIS) monitoring, as a non-invasive diagnostic method, can effectively analyze the internal state of electrochemical cells by analyzing their impedance response under different frequency excitations, providing a basis for early fault warning and health management.

[0004] To achieve EIS monitoring, an alternating current needs to be injected into the electrochemical cell. It is currently known to use a DC-DC converter connected to the DC bus of the electrochemical cell to inject AC current for EIS monitoring. By adjusting the duty cycle of the power switching devices in the DC-DC converter, a small AC current can be superimposed on the DC bus current, thereby stimulating the impedance response of the electrochemical cell.

[0005] However, the alternating current injected in this way can only have a relatively low frequency, with the highest frequency being, for example, 1 kHz. This results in insufficient spectral coverage for EIS monitoring. This injection method is insufficient to meet the requirements for EIS monitoring of electrochemical cells in a higher frequency range.

[0006] Therefore, existing electrochemical battery systems still have shortcomings in AC injection into electrochemical cells. Utility Model Content

[0007] The purpose of this application is to provide an improved electrochemical battery system for vehicles, in order to at least partially overcome the shortcomings of the prior art.

[0008] According to a first aspect of this application, an electrochemical battery system for a vehicle is provided, the electrochemical battery system comprising: an electrochemical battery adapted to provide electrical energy to a load; an AC generating device adapted to generate alternating current; and an AC transformer, wherein the primary coil of the AC transformer is connected to the AC generating device, and the secondary coil of the AC transformer is connected in series with the electrochemical battery and the load to the output terminal of the electrochemical battery, thereby injecting alternating current from the primary coil into the electrochemical battery via the secondary coil through electromagnetic induction.

[0009] According to an exemplary embodiment of this application, the electrochemical battery system further includes a DC-DC converter adapted to be connected between the electrochemical battery and a load, the DC-DC converter including an input capacitor. The secondary coil of an AC transformer may be connected in series between the output terminal of the electrochemical battery and the input capacitor of the DC-DC converter.

[0010] According to an exemplary embodiment of this application, the AC generating device includes four power switching devices connected in an H-bridge circuit structure, the H-bridge circuit structure having a DC input terminal adapted to be connected to a DC power supply and an AC output terminal connected to the primary coil of an AC transformer.

[0011] According to an exemplary embodiment of this application, the AC generating device includes two power switching devices and two second capacitors connected in a half-bridge circuit structure, the half-bridge circuit structure having a DC input terminal adapted to be connected to a DC power supply and an AC output terminal connected to the primary coil of an AC transformer.

[0012] According to an exemplary embodiment of this application, the AC generating device further includes a first capacitor connected in parallel between the DC input terminals of the respective H-bridge circuit structure or half-bridge circuit structure.

[0013] According to an exemplary embodiment of this application, the electrochemical battery system further includes a frequency regulator communicatively connected to an AC generator, thereby adjusting the frequency of the AC current generated by the AC generator by adjusting the switching frequency of the power switching devices of the AC generator. The highest frequency of the AC current can be, in particular, above 20 kHz.

[0014] According to an exemplary embodiment of this application, the number of turns of the primary coil of the AC transformer is greater than the number of turns of the secondary coil.

[0015] According to an exemplary embodiment of this application, the AC transformer is a turns-ratio adjustable transformer.

[0016] According to an exemplary embodiment of this application, at least one of the primary coil and the secondary coil is provided with a plurality of taps connected at different turns positions. The AC transformer may include a tap changer selectively connected to one of the plurality of taps.

[0017] According to an exemplary embodiment of this application, the electrochemical battery system further includes: a first sensor arranged to detect the voltage across the electrochemical battery; a second sensor arranged to detect the current flowing through the electrochemical battery; and an impedance analyzer adapted to perform impedance characteristic analysis, connected to the first sensor and the second sensor.

[0018] According to an exemplary embodiment of this application, the electrochemical cell is a fuel cell.

[0019] According to an exemplary embodiment of this application, the electrochemical battery is a power battery for a vehicle.

[0020] According to this application, an AC transformer can directly inject AC current generated by an AC generator into an electrochemical cell. This allows the AC current injected into the electrochemical cell to have a higher frequency without being limited by other devices. Therefore, AC current can be injected into the electrochemical cell over a wider frequency range. Consequently, electrochemical impedance can be monitored over a wider frequency range. Attached Figure Description

[0021] The principles, features, and advantages of this application will be better understood below with reference to the accompanying drawings. The drawings include:

[0022] Figure 1 An existing electrochemical battery system is shown;

[0023] Figure 2 The structure of an electrochemical battery system for a vehicle according to an exemplary embodiment of this application is schematically shown;

[0024] Figure 3 The structure of an electrochemical battery system according to an exemplary embodiment of this application is schematically shown;

[0025] Figure 4 The structure of an electrochemical battery system according to an exemplary embodiment of this application is schematically illustrated; and

[0026] Figure 5 An AC transformer of an electrochemical battery system according to an exemplary embodiment of this application is schematically shown. Detailed Implementation

[0027] To make the technical problems to be solved, the technical solutions, and the beneficial technical effects of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit the scope of protection of this application.

[0028] It should be understood that the terms "first," "second," etc., used herein are for descriptive purposes only and should not be construed as indicating or implying relative importance, nor should they be construed as implicitly specifying the number of technical features indicated. Features specified as "first" or "second" may expressly or implicitly indicate that at least one of those features is included.

[0029] To better understand the concept of this application, let's first combine it with... Figure 1 Explain the existing methods for injecting alternating current into electrochemical cells.

[0030] Figure 1 An existing electrochemical battery system 1 is shown. The electrochemical battery system 1 includes an electrochemical battery 11 and a DC-DC converter 12. The DC-DC converter 12 is connected between the electrochemical battery 11 and a load 2 to convert the voltage output by the electrochemical battery 11 into a voltage suitable for the load 2.

[0031] The DC-DC converter 12 includes an input capacitor 121, an inductor, power switching devices, and an output capacitor. By controlling the power switching devices of the DC-DC converter 12 to alternately turn on and off, the voltage conversion function of the DC-DC converter 12 can be realized.

[0032] Furthermore, the DC-DC converter 12 can be used to inject alternating current into the electrochemical cell 11. Specifically, an alternating current component can be generated by changing the duty cycle of the power switching device 131 of the DC-DC converter 12, and this alternating current component is superimposed on the direct current output by the electrochemical cell 11.

[0033] This injection method enables low-frequency AC injection but struggles with high-frequency AC injection. This is because the input capacitor 121 has a low impedance to high-frequency AC currents, causing the current to pass through it and not be injected into the electrochemical cell 11. Even if the DC-DC converter 12 generates a high-frequency AC current, this current will be released by the input capacitor 121. Therefore, the frequency of the AC current injected into the electrochemical cell 11 is limited, making it difficult to achieve EIS monitoring over a wider frequency range.

[0034] With the development of battery technology, there is a need to perform EIS monitoring of electrochemical cells at higher frequencies (e.g., 20 kHz) to obtain more comprehensive electrochemical cell state information. Existing AC injection methods are insufficient to meet this requirement.

[0035] Figure 2 The structure of an electrochemical battery system 1 for a vehicle according to an exemplary embodiment of this application is schematically shown. The electrochemical battery system 1, in particular, provides power for driving the vehicle.

[0036] like Figure 2 As shown, the electrochemical battery system 1 includes an electrochemical battery 11. The electrochemical battery 11 can be of various types. For example, the electrochemical battery 11 may include a fuel cell, particularly a hydrogen fuel cell. The electrochemical battery 11 is capable of generating electrical energy through an electrochemical reaction, thereby powering a load 2. The load 2 may include, for example, an energy storage device (e.g., a high-voltage battery), a drive motor, or an onboard air conditioning system.

[0037] The electrochemical cell system 1 also includes an AC generator 13 adapted to generate alternating current and an AC transformer 14. The primary coil 141 of the AC transformer 14 is connected to the AC generator 13. The secondary coil 142 of the AC transformer 14 is connected in series with the electrochemical cell 11 and the load 2 to the output terminal of the electrochemical cell 11, thereby injecting alternating current from the primary coil 141 into the electrochemical cell 11 through the secondary coil 142 via electromagnetic induction.

[0038] The AC transformer 14 can directly inject the AC current generated by the AC generator 13 into the electrochemical cell 11. This allows the AC current injected into the electrochemical cell 11 to have a higher frequency without being limited by other devices. Therefore, AC current can be injected into the electrochemical cell 11 over a wider frequency range. Consequently, EIS monitoring can be performed over a wider frequency range.

[0039] The highest frequency of the alternating current generated by the alternating current generator 13 and injected into the electrochemical cell 11 through the alternating current transformer 14 can be above 20 kHz. This allows EIS monitoring to cover a wider frequency range in order to obtain more comprehensive electrochemical cell status information.

[0040] As described above, the electrochemical battery system 1 may further include a DC-DC converter 12 connected between the electrochemical battery 11 and the load 2. The DC-DC converter 12 includes an input capacitor 121. The secondary coil 142 of the AC transformer 14 may be connected in series between the output terminal of the electrochemical battery 11 and the input capacitor 121 of the DC-DC converter 12. The AC current generated by the AC generating device 13 can be directly injected into the electrochemical battery 11 via the secondary coil 142 of the AC transformer 14 without passing through the input capacitor 121. Thus, it is possible to prevent high-frequency AC current from being filtered by the input capacitor 121, thereby preventing high-frequency AC current from being injected into the electrochemical battery 11.

[0041] The secondary coil 142 of the AC transformer 14 can be connected, for example, to the positive output terminal of the electrochemical cell 11. Alternatively, it is also feasible to connect the secondary coil 142 to the negative output terminal of the electrochemical cell 11.

[0042] Figure 3 The structure of an electrochemical battery system 1 according to an exemplary embodiment of this application is schematically shown.

[0043] Similar to the embodiments described above, the electrochemical battery system 1 includes an electrochemical battery 11, an AC generator 13, and an AC transformer 14.

[0044] In this embodiment, the AC generating device 13 may include four power switching devices 131 connected in an H-bridge circuit structure. The H-bridge circuit structure has a DC input terminal suitable for connection to the DC power supply 3 and an AC output terminal connected to the primary coil 141 of the AC transformer 14.

[0045] The DC power supply 3 may include a DC power supply with a rated frequency of 800V or a DC power supply with a rated frequency of 24V. For example, the DC power supply 3 may be a high-voltage battery or a low-voltage battery of the vehicle.

[0046] See Figure 3 The H-bridge circuit structure may include a left and right bridge arm connected in parallel to each other to the DC power supply 3. Each of the left and right bridge arms may have two power switching devices 131 connected in series. AC output terminals are respectively connected between the two series-connected power switching devices 131. The power switching devices 131 may include, for example, MOSFETs or IGBTs. By controlling the four power switching devices 131 to alternately turn on and off, an AC voltage can be generated between the AC output terminals. This allows AC current to flow through the primary coil 141 connected to the AC output terminals.

[0047] With the help of this H-bridge circuit structure, the DC current provided by the DC power supply 3 can be converted into AC current and output to the primary coil 141 of the AC transformer 14. This AC generating device 13 can output pure AC current without DC bias.

[0048] The AC generator 13 may also include a first capacitor 132 connected in parallel between the DC input terminals of the H-bridge circuit structure. The first capacitor 132 is capable of attenuating voltage spikes at the DC input terminals, absorbing high pulse currents, and providing instantaneous power to the AC output terminals.

[0049] According to an exemplary embodiment of this application, the number of turns of the primary coil 141 of the AC transformer 14 may be greater than the number of turns of the secondary coil 142. This helps to ensure that there is a lower voltage across the secondary coil 142 of the AC transformer 14. Therefore, the injection of alternating current can be prevented from affecting the normal operation of the electrochemical system.

[0050] like Figure 3As shown, the electrochemical battery system 1 may further include a frequency regulator 15. The frequency regulator 15 is communicatively connected to the AC generator 13 so as to adjust the frequency of the AC current generated by the AC generator 13 by adjusting the switching frequency of the power switching device 131 of the AC generator 13. The highest frequency of the AC current may be above 20 kHz.

[0051] In response to an adjustment signal from the frequency regulator 15, the AC generator 13 can adjust the switching frequency of its power switching device 131 accordingly to generate an AC current with the desired frequency. The frequency regulator 15 can, for example, cause the AC generator 13 to generate an AC current with a maximum frequency of 20 kHz or higher.

[0052] By cooperating with the frequency regulator 15 and the AC generator 13, an adjustable AC current can be provided over a wide frequency range.

[0053] The electrochemical cell system 1 may further include a first sensor 16, a second sensor 17, and an impedance analyzer 18. The first sensor 16 is arranged to detect the voltage across the electrochemical cell 11. The second sensor 17 is arranged to detect the current flowing through the electrochemical cell 11. The impedance analyzer 18 can be connected to the first sensor 16 and the second sensor 17 to perform impedance characteristic analysis based on the detection results of the first sensor 16 and the second sensor 17. The impedance analyzer 18 can perform electrochemical impedance spectroscopy analysis based on the voltage across the electrochemical cell 11 and the current flowing through the electrochemical cell 11 detected by the first sensor 16 and the second sensor 17.

[0054] Impedance analyzer 18 can determine the impedance characteristics of electrochemical cell 11 based on the following relationship: Z = U / I, where Z represents the impedance of electrochemical cell 11, U represents the measured voltage across electrochemical cell 11, and I represents the measured current flowing through electrochemical cell 11.

[0055] The electrical, physical, and / or chemical properties of the electrochemical cell 11 can be analyzed using impedance Z.

[0056] Taking hydrogen fuel cells as an example, by identifying the impedance modulus of the hydrogen fuel cell at a predetermined characteristic frequency, it can be determined whether the hydrogen fuel cell has experienced a gas starvation fault. For example, at the first characteristic frequency, if the impedance modulus of the hydrogen fuel cell differs significantly from a predetermined modulus reference value, then a gas starvation fault can be identified in the hydrogen fuel cell.

[0057] Furthermore, at the second characteristic frequency, if the phase of the impedance of the hydrogen fuel cell differs significantly from a predetermined phase reference value, a hydrogen starvation fault can be identified in the hydrogen fuel cell; otherwise, an air starvation fault can be identified. The second characteristic frequency is particularly greater than the first characteristic frequency.

[0058] By combining a lower first characteristic frequency and a higher second characteristic frequency, it is possible to identify whether a hydrogen fuel cell is experiencing a gas starvation fault and to further distinguish whether the identified gas starvation fault is a hydrogen starvation fault or an air starvation fault.

[0059] In addition, the high-frequency resistance and low-frequency impedance of electrochemical impedance spectroscopy can be used as diagnostic indicators for insufficient water content and excessive water content inside hydrogen fuel cells, respectively.

[0060] The first sensor 16 may include a voltage sensor connected to both ends of the electrochemical cell 11. The second sensor 17 may include a current sensor connected in series with the electrochemical cell 11.

[0061] Optionally, the impedance analyzer 18 and the frequency regulator 15 can be integrated together.

[0062] Figure 4 The structure of an electrochemical battery system 1 according to an exemplary embodiment of this application is schematically shown. Similar to the embodiments described above, Figure 4 The electrochemical battery system 1 shown includes an electrochemical battery 11, an AC generator 13, and an AC transformer 14.

[0063] and Figure 3 The embodiments shown are different, in Figure 4 In the embodiment shown, the AC generating device 13 includes two power switching devices 131 and two second capacitors 133 connected in a half-bridge circuit structure. The half-bridge circuit structure has a DC input terminal suitable for connection to the DC power supply 3 and an AC output terminal connected to the primary coil 141 of the AC transformer 14.

[0064] See Figure 4 The half-bridge circuit structure may include a left bridge arm and a right bridge arm connected in parallel to the DC power supply 3. The two power switching devices 131 are arranged in series in the left bridge arm, and the two second capacitors 133 are arranged in series in the right bridge arm. The AC output terminals are respectively connected between the two series-connected power switching devices 131 and between the two series-connected second capacitors 133. By controlling the two power switching devices 131 to alternately turn on and off, an AC voltage can be generated between the AC output terminals.

[0065] The AC generating device 13 may also include a first capacitor 132 connected in parallel between the DC input terminals of the half-bridge circuit structure.

[0066] According to an exemplary embodiment of this application, the AC transformer 14 of the electrochemical battery system 1 is an adjustable-turns transformer. This helps ensure that the secondary coil 142 of the AC transformer 14 has the desired voltage, thereby preventing the injection of AC current from affecting the normal operation of the electrochemical system.

[0067] Figure 5 An AC transformer 14 of an electrochemical battery system 1 according to an exemplary embodiment of this application is schematically shown.

[0068] In this embodiment, the AC transformer 14 of the electrochemical battery system 1 is a tap-switch type transformer. For example... Figure 5 As shown, the AC transformer 14 includes a primary coil 141 and a secondary coil 142. The AC transformer 14 also includes other components such as an iron core, which are not shown here.

[0069] The primary coil 141 may have multiple taps connected to specific turns positions of the primary winding. The AC transformer 14 may include a tap changer 143, which can select one of the multiple taps as the effective terminal for actual circuit connection, thereby changing the effective number of turns of the primary coil 141. Thus, the turns ratio of the AC transformer 14 can be changed.

[0070] Alternatively or additionally, the secondary coil 142 may be provided with multiple taps connected to specific turns positions of the secondary winding. The AC transformer 14 may include a tap changer for selecting the effective number of turns of the secondary coil 142.

[0071] Although specific embodiments of this application are described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of this application. Various substitutions, modifications, and combinations may be conceived without departing from the spirit and scope of this application. Features of the various embodiments may be separated or combined to form other implementations not expressly described or illustrated herein, which still fall within the protection scope of this application.

Claims

1. An electrochemical battery system for a vehicle, characterized in that, The electrochemical battery system (1) includes: An electrochemical cell (11) suitable for providing electrical energy to a load (2); An AC generator suitable for generating alternating current (13); and AC transformer (14), The primary coil (141) of the AC transformer (14) is connected to the AC generator (13), and the secondary coil (142) of the AC transformer (14) is connected in series with the electrochemical cell (11) and the load (2) to the output terminal of the electrochemical cell (11), thereby injecting AC current from the primary coil (141) into the electrochemical cell (11) through the secondary coil (142) via electromagnetic induction.

2. The electrochemical battery system according to claim 1, characterized in that, The electrochemical battery system (1) also includes a DC-DC converter (12) adapted to be connected between the electrochemical battery (11) and the load (2), the DC-DC converter (12) including an input capacitor, and the secondary coil (142) of an AC transformer (14) being connected in series between the output terminal of the electrochemical battery (11) and the input capacitor of the DC-DC converter (12).

3. The electrochemical battery system according to claim 1 or 2, characterized in that, The AC generator (13) includes: Four power switching devices (131) are connected in an H-bridge circuit structure, the H-bridge circuit structure having a DC input terminal suitable for connection to a DC power supply (3) and an AC output terminal connected to the primary coil (141) of an AC transformer (14); or Two power switching devices (131) and two second capacitors (133) are connected in a half-bridge circuit structure, the half-bridge circuit structure having a DC input terminal suitable for connection to a DC power supply (3) and an AC output terminal connected to the primary coil (141) of an AC transformer (14).

4. The electrochemical battery system according to claim 3, characterized in that, The AC generating device (13) also includes a first capacitor (132) connected in parallel between the DC input terminals of the corresponding H-bridge circuit structure or half-bridge circuit structure.

5. The electrochemical battery system according to claim 3, characterized in that, The electrochemical battery system (1) also includes a frequency regulator (15) which is communicatively connected to an AC generator (13) to adjust the frequency of the AC current generated by the AC generator (13) by adjusting the switching frequency of the power switching device (131) of the AC generator (13), wherein the highest frequency of the AC current is above 20 kHz.

6. The electrochemical battery system according to any one of claims 1-2 and 4-5, characterized in that, The number of turns of the primary coil (141) of the AC transformer (14) is greater than the number of turns of the secondary coil (142).

7. The electrochemical battery system according to any one of claims 1-2 and 4-5, characterized in that, The AC transformer (14) is a transformer with adjustable turns ratio.

8. The electrochemical battery system according to claim 7, characterized in that, At least one of the primary coil (141) and the secondary coil (142) is provided with multiple taps connected at different turns positions; The AC transformer (14) includes a tap changer (143) that is selectively connected to one of the plurality of taps.

9. The electrochemical battery system according to any one of claims 1-2, 4-5, and 8, characterized in that, The electrochemical battery system (1) also includes: A first sensor (16) is arranged to detect the voltage across the electrochemical cell (11); A second sensor (17) is arranged to detect the current flowing through the electrochemical cell (11); and An impedance analyzer (18) suitable for performing impedance characteristic analysis is connected to a first sensor (16) and a second sensor (17).

10. The electrochemical battery system according to any one of claims 1-2, 4-5, and 8, characterized in that, The electrochemical cell (11) is a fuel cell; and / or The electrochemical battery (11) is the power battery for the vehicle.

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