Energy source system with state determination

Abstract

The invention relates to an energy source system (10) with state determination, comprising an energy source (14) designed as an electrochemical converter, the energy source comprising a first converter type (18) via which direct current can be supplied to an electrical load (26), and a signal analyzer (42) electrically connected to the energy source (14), with the aid of which an impedance response to a frequency-inductive load signal of the energy source (14) can be measured by current or voltage measurement, so that the state of the energy source can be determined based on the impedance response of the energy source (14). The energy source (14) further comprises at least one second converter type (22) different from the first converter type (18), which is also electrically connected to the signal analyzer (42), so that the state of the second converter type (22) can be determined by the signal analyzer (42).

Description

Technical Field

[0001] The invention relates to an energy source system with state determination and a method for determining the state of an energy source in an energy source system. Background Art

[0002] Today's fuel cell and battery systems are costly, and reliability and durability are challenging, especially for automotive applications. Furthermore, field experience and data on factors such as failure statistics and system-related aging functions remain limited. This often leads to costly oversizing of system components in today's systems.

[0003] Controlling the various system components (e.g., stack, compressor, battery) via operating strategies requires precise knowledge of their states. For example, knowledge of the temperature, humidity, pressure, stoichiometry, voltage, and current in the fuel cell stack is crucial in order to estimate derived variables such as power reserve, waste heat, and aging.

[0004] DE 10 2013 103 921 A1 discloses a temperature measurement system for battery cells in a battery pack and a method for performing such temperature measurement. Temperature measurement is performed without a temperature sensor. The measured battery cell temperature can be used to improve the performance and service life of the battery cells. To measure the battery cell temperature, an AC voltage signal is applied to the battery cell. Based on the frequency of the AC voltage signal used, the impedance of the battery cell can be determined. Subsequently, the temperature can be determined from the impedance and frequency based on a stored map for the battery cell.

[0005] Current mobile vehicle fuel cell systems mostly have batteries for hybridization, in order to benefit, for example, from the possibilities of energy recuperation and power support. Summary of the Invention

[0006] Based on the above-mentioned prior art, the present invention is based on the following object: to provide an energy source system with which the state of various electrochemical converters can be economically determined. This object is achieved by the technical solution of the present invention. Preferred embodiments can be derived from the further technical solution.

[0007] The present invention describes an energy source system with state determination. The energy source system includes an energy source configured as an electrochemical converter, the energy source comprising a first converter type, via which direct current can be supplied to an electrical load, and a signal analyzer electrically connected to the energy source. The signal analyzer can be used to measure an impedance response to a frequency-induced load signal of the energy source by current or voltage measurement, thereby enabling the state of the energy source to be determined based on the impedance response of the energy source. The energy source also includes at least one second converter type, different from the first converter type, which is also electrically connected to the signal analyzer, so that the state of the second converter type can be determined by the signal analyzer.

[0008] For the purposes of the present invention, "state determination" is understood as meaning the ability to determine specific values ​​of an energy source, such as temperature, humidity, aging state, and state of charge. According to the present invention, an electrochemical converter is an energy source that converts stored chemical energy into electrical energy. According to the present invention, an electrochemical converter can be not only a converter but also a storage device that stores electrical energy again in the form of chemical energy. The term "converter type" distinguishes between the way an electrochemical converter operates in providing electrical energy and how it functions in comparison to other converter types.

[0009] In this context, a "load signal" is understood to be a signal that causes a chemical, electrochemical, and sometimes also a physical conversion in the electrochemical converter. Accordingly, a specific amount of electrical energy can be withdrawn from the converter. The load signal can be positive or negative, i.e., it can be generated solely from a charge direction signal or a discharge direction signal. In particular, the load signal is applied at a specific frequency or frequency band.

[0010] According to the present invention, two different converter types are connected to the same signal analyzer. The different converter types can thus incorporate their respective advantages into the energy source system, effectively complementing each other and thus leading to improved performance of the overall energy source system. Furthermore, only a single signal analyzer is required to determine the state of the energy source, eliminating the need for an additional signal analyzer and its required power. State determination also enables optimized system design of the energy source, for example, avoiding oversizing of components. It also increases component lifespan, resulting in economical state determination.

[0011] In a preferred embodiment of the present invention, the first converter type is a battery and / or the second converter type is a fuel cell unit. This combination of different converter types has the advantage that their properties complement each other positively. For example, the battery can also be used as an energy storage device, allowing energy recovered through recycling to be stored again in the battery. This improves the efficiency of the energy source system.

[0012] In an alternative embodiment, the first converter type and the second converter type are batteries of different embodiment variants. Preferably, the first converter is a lithium battery or a lithium high-power battery, and the second converter type is a supercapacitor or a lithium high-energy battery. These different battery types complement each other synergistically in the energy source system and lead to improved overall performance.

[0013] In another preferred embodiment of the present invention, the signal analyzer includes a frequency trigger unit, by means of which a frequency-induced load signal can be applied. Thus, the frequency trigger unit and the signal analyzer are implemented in a single component. Consequently, no additional, separate installation space is required for the frequency trigger unit. This reduces the number of components and increases the integration level of the energy source system.

[0014] Preferably, a power electronic component is arranged between the electrical consumer and the energy source, and the power electronic component is configured to apply a frequency-induced load signal. The power electronic component preferably includes a DC / DC converter and a DC / AC converter. Therefore, the DC / DC converter or DC / AC converter has the following function: with the help of the DC / DC converter or DC / AC converter, a load signal is applied to the converter at a predetermined frequency. Natural noise or noise of the load in the application can also be used as a signal source. For example, the load signal can be applied during continuous operation. Therefore, no additional frequency trigger unit is required to apply the frequency-induced load signal. This reduces the number of required components, making it possible to manufacture such an energy source system more economical.

[0015] In one advantageous embodiment, the signal analyzer is located between the power electronics and the energy source and is electrically connected thereto. Thus, the signal analyzer is connected directly (i.e., without intermediate components) to the energy source. This prevents such components from influencing the response signal. This allows for accurate determination of the energy source's state.

[0016] In another advantageous embodiment, at least one converter type has battery cells, and the signal analyzer is connected to selected battery cells of the at least one converter type to determine the status of the converter type. The signal analyzer therefore does not analyze the overall signal of the converter. Preferably, individual battery cells or groups of battery cells are selected that are specific to the status of the converter type, or the battery cells that typically deteriorate first are selected. This allows for a more accurate determination of the status of the converter type.

[0017] According to one advantageous embodiment, the first converter type and the second converter type are arranged in parallel or in series with one another, and the signal analyzer is electrically connected such that a sum signal from the first converter type and the second converter type can be measured. The signal analyzer thus measures the signals of the converter types simultaneously. In another embodiment, in the case of a series connection, and in the case of a parallel connection when individual current sensors with individual memories are present, the corresponding individual voltage signals of the individual memories can also be analyzed to form a uniquely assigned impedance value.

[0018] In another embodiment, the corresponding partial signals can be determined from the sum signal based on knowledge of the characteristics of the individual converter types. This has the advantage that the signal analyzer does not have to switch between converter types to measure the response signal or apply a frequency-induced load signal. Furthermore, a simpler circuit can be achieved through a parallel or series connection. In this context, the following generally applies: For example, the sensitive frequency ranges of the two converter types are often different, and thus the effect can be directly assigned to the respective converter type. This is achieved by isolating the effect in the frequency domain.

[0019] The present invention also describes a method for determining the state of an energy source in an energy source system. The method comprises the following steps: applying a frequency-induced load signal to at least one converter type; measuring the impedance response by current or voltage measurement; and determining the state of the at least one converter type. This method achieves the aforementioned advantages.

[0020] In a preferred embodiment, the signal analyzer measures the first and second converter types simultaneously or switches between them for measurement. During switching, the converter types are switched so that only one converter type is measured. This prevents the influence of the other converter type. Conversely, switching can be omitted for simultaneous measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] An exemplary embodiment of the present invention is illustrated in the drawings and is explained in more detail in the following description.

[0022] Figure 1 The structure of a first embodiment of an energy source system with state determination is shown;

[0023] Figure 2 The structure of a second embodiment of an energy source system with state determination is shown;

[0024] Figure 3 The structure of a third embodiment of an energy source system with state determination is shown;

[0025] Figure 4 The structure of a fourth exemplary embodiment of an energy source system with state determination is shown. DETAILED DESCRIPTION

[0026] exist Figure 1 shows the structure of a first exemplary embodiment of a state-determined energy source system 10. Energy source system 10 includes an energy source 14 configured as an electrochemical converter. Energy source 14 comprises two different converter types 18 and 22. The first converter type 18 is a battery, while the second converter type 22 is configured as a fuel cell unit. Both converter types 18 and 22 are connected to an electrical load 26 to supply it with energy. In this exemplary embodiment, electrical load 26 is configured as, for example, the engine of a motor vehicle.

[0027] Power electronics 30 are arranged between the engine 26 and the converter types 18 and 22. In this embodiment, power electronics 30 consists of two DC / DC converters 34 and a DC / AC converter 38. Each converter type 18 and 22 is assigned a separate DC / DC converter 34, which converts the DC voltage of the corresponding converter type 18 and 22 into the desired DC voltage. In contrast to the DC / DC converter 34 of the fuel cell unit 22, the DC / DC converter 34 of the battery 18 is a bidirectional converter, allowing energy, for example, recovered through recuperation, to be fed back into the battery 18 and stored there. The outputs of the two DC / DC converters 34 are connected to each other and to the DC / AC converter 38. The DC / AC converter 38 converts the DC voltage received from the DC / DC converters 34 into an AC voltage for the engine 26. Therefore, the DC / AC converter 34 is arranged between the engine 26 and the DC / DC converter 34.

[0028] Energy source system 10 also includes a signal analyzer 42 for determining the status of converter types 18 and 22. This signal analyzer 42 is electrically connected between the respective DC / DC converter 34 and converter types 18 and 22. In this exemplary embodiment, signal analyzer 42 includes a frequency trigger unit 46, which can be used to apply a frequency-induced load signal to the respective converter type 18 and 22. In this exemplary embodiment, the load signal is applied in the form of a current signal with a specific frequency and amplitude. Similarly, a voltage signal can also be applied as the load signal.

[0029] Here, load signals in the form of current signal I1 for fuel cell unit 22 and current signal I2 for battery 18 can be applied alternately to fuel cell unit 22 and battery 18. The voltage signals U1 and U2 resulting from the impedance response of the respective converter types 18 and 22 are measured by signal analyzer 42, and the state of the respective converter types 18 and 22 is determined from them. However, current signals I1 and I2 can also be applied simultaneously to battery unit 18 and fuel cell unit 22. However, when current signals I1 and I2 are coupled in simultaneously, it is necessary to cumulatively determine the individual current components upstream of fuel cell unit 22 and battery 18.

[0030] Figure 2 The structure of a second embodiment of an energy source system 10 with state determination is shown. Figure 1 The first exemplary embodiment shown in FIG differs in that the voltage signals U1, U2 are not measured downstream of the fuel cell unit 22 or the battery 18 to determine the overall voltage. Instead, the signal analyzer 42 is connected to selected cells 50, 54 to measure the voltage signals U1, U2. Measurements can also be made across two cells 50, 54, for example. These selected cells 50, 54 are particularly representative of the state of the entire converter type 18, 22 or are particularly often the first cell 50, 54 to have a defect. Based on the impedance and state of the selected cells 50, 54, the overall impedance and state of the converter type 18, 22 can be inferred.

[0031] The structure of the third embodiment of the energy source system 10 with state determination is Figure 3 . This embodiment differs from the two previous embodiments in that the battery 18 and the fuel cell unit 22 are directly connected to each other. The battery 18 and the fuel cell unit 22 can be connected in parallel or in series. Therefore, both converter types 18 and 22 are connected to only one DC / DC converter 34, eliminating the need for a second DC / DC converter 34.

[0032] In this third embodiment, a load signal is applied to both the DC / DC converter 34 and the battery 18 or fuel cell unit 22. This results in voltage signals U1 and U2 being the sum of the signals from the battery 18 and fuel cell unit 22. To draw conclusions about the state of the respective individual converter types 18 and 22, the resulting sum signal is first analyzed in the frequency range. The state can be determined based on existing knowledge and / or models.

[0033] exist Figure 4 shows the structure of a fourth exemplary embodiment of an energy source system 10 with state determination. This exemplary embodiment differs substantially from the third exemplary embodiment in that the signal analyzer 42 does not include a frequency trigger unit 46. In contrast to the preceding exemplary embodiments, the load signal is generated by the power electronics 30. A DC / DC converter 34 or a DC / AC converter 38 can be provided accordingly. For this purpose, the load change at the required frequency is determined, for example, by the DC / DC converter 34, so that the impedance response can be measured by the signal analyzer 42. This makes it possible to dispense with the frequency trigger unit 46 in the signal analyzer 42.

Claims

1. An energy source system (10) with state determination, comprising an energy source (14) configured as an electrochemical converter and a signal analyzer (42), wherein the energy source (14) comprises a first converter type (18) via which direct current can be supplied to an electrical load (26), the signal analyzer (42) being electrically connected to the energy source (14), and by means of the signal analyzer (42) being able to measure an impedance response to a frequency-induced load signal of the energy source (14) by current measurement or voltage measurement, so that the state of the energy source (14) can be determined based on the impedance response of the energy source (14), characterized in that The energy source (14) further comprises at least one second converter type (22) different from the first converter type (18), the second converter type (22) also being electrically connected to the signal analyzer (42) so that the state of the second converter type (22) can be determined by the signal analyzer (42), wherein a power electronic component (30) is arranged between the electrical consumer (26) and the energy source (14), the power electronic component being configured to apply the frequency-induced load signal, wherein a separate DC / DC converter is assigned to each converter type, wherein each DC / DC converter converts the DC voltage of the corresponding converter type into a desired DC voltage, wherein the load signal is generated by each DC / DC converter, wherein the impedance response of the first converter type (18) and the second converter type (22) is measured respectively by the signal analyzer (42).

2. The energy source system (10) according to claim 1, characterized in that The first converter type (18) is a battery and / or the second converter type (22) is a fuel cell unit.

3. The energy source system (10) according to claim 1 or 2, characterized in that The signal analyzer (42) is electrically connected to the energy source (14) between the power electronic component (30) and the energy source (14).

4. The energy source system (10) according to claim 1 or 2, characterized in that At least one converter type (18, 22) has a battery cell (50, 54), wherein, in order to determine the state of the converter type (18, 22), the signal analyzer (42) is connected to a selected battery cell (50, 54) of the converter type (18, 22).

5. The energy source system (10) according to claim 1 or 2, characterized in that The first converter type (18) and the second converter type (22) are arranged in parallel or in series with one another, and the signal analyzer (42) is electrically connected such that a sum signal from the first converter type (18) and the second converter type (22) can be measured.

6. A method for determining the state of an energy source (14) in an energy source system (10) according to any one of the preceding claims, wherein: The method comprises the following steps: applying a frequency-induced load signal to at least one converter type (18, 22); measuring an impedance response by current measurement or voltage measurement; and determining a state of the at least one converter type (18, 22).

7. The method according to claim 6, characterized in that The signal analyzer (42) measures the first converter type (18) and the second converter type (22) simultaneously or switches between the first converter type (18) and the second converter type (22) for measurement.

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