Overcurrent protection

Abstract

The present teachings relate to a protection circuit for protecting an electric power system, comprising: a current sensor configured to generate an electrical signal, wherein the current sensor has a measurement dynamic range; a rectification module configured to generate a pulsating DC signal; a superposition module configured to generate an extended signal; a low-pass filter configured to shape the extended signal to generate a band-limited signal; a logic module configured to generate a trip signal when the band-limited signal violates a predetermined threshold; wherein the trip signal can be used to cut off the flow of AC current. The present teachings also relate to related methods and software products.

Description

[0001] This application claims priority to European Patent Application No. 24166524.9, filed on 26 March 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This teaching relates to protective circuits used to protect power systems. This teaching also relates to methods and software products.

[0003] Electrical systems for supplying off-grid power to various loads are known from the prior art. These electrical systems can be used as power-consuming appliances (such as power tools on construction sites), lighting equipment, emergency appliances (e.g., pumps), or any type of mobile equipment, as well as electrical outlets in situations where no permanent power supply is available. In particular, it may be desirable for these electrical systems to be portable.

[0004] To conveniently power a wide variety of appliances, such a power system can be designed to provide AC power at the power output, and it can even be charged via the power input (e.g., using AC power).

[0005] Typically, power systems are equipped with protective devices (such as circuit breakers or fuses) that interrupt the power circuit in the event of a harmful overcurrent to prevent damage to the power system. However, in some power systems, it may be desirable to have large peak load capacity, which allows for temporary large peak currents, such as those that rotating tools or motors may require during startup. Therefore, for proper functioning, the protective circuitry will need to operate in both modes to prevent unwanted interruptions during peak loads and to protect the system during overcurrent events.

[0006] Some of the aforementioned problems associated with the prior art will be shown to be addressed by utilizing the subject matter of the independent claims appended herein. Dependent claims and the description will show certain additional advantages.

[0007] Protective devices such as standard miniature circuit breakers combine the tripping mechanism and the disconnect point into a single component, and this device is looped into the line to be protected. When the circuit breaker trips (e.g., due to overcurrent), the disconnect point opens and the line is de-energized to prevent damage (e.g., to circuit components associated with the line). In some cases, two tripping mechanisms can be superimposed: for example, a thermal tripping mechanism, which reacts slowly and is sensitive to a more sustained increase in line current exceeding its rated value. Alternatively, a faster tripping mechanism (e.g., a magnetic tripping mechanism) can be provided, which is sensitive to high line current values ​​for a short period of time. The current-time characteristics of such devices can be very complex. In some cases, the current-time characteristics of the power system may be inconsistent with the current-time characteristics of such protective devices, leading to erroneous tripping of the circuit.

[0008] Furthermore, in some applications, it may be desirable for the power system to provide multiple types of output voltages. For example, a power system that can operate on (input and / or output) 240 V AC mains and 120 V AC mains (e.g., in the same or independent configurable modes) can allow the same system to handle the power consumption and / or input rated for either of these voltage domains. It should be recognized that the 240 V 50 Hz AC domain is primarily used in Europe, while the 120 V 60 Hz AC domain is primarily used in the United States. It should be understood that the precise voltage values ​​and / or frequencies of the voltage domains are not necessary for the generality or scope of this teaching. In terms of voltage and / or frequency, there can even be more than two of any standard or non-standard types of domains. For example, while the mains frequency is 50 Hz in Europe and typically 60 Hz in the United States, this teaching can even allow for 50 Hz 120 V AC or 60 Hz 240 V AC. Therefore, this teaching can be applied to virtually any voltage domain and any frequency.

[0009] Therefore, the fundamental purpose of this teaching is to provide a protection circuit for protecting power systems, as well as a method and software product for providing overcurrent protection. The protection circuit, method, and software product can be adapted to different output parameters, such as different AC output voltages.

[0010] The protective circuit for protecting a power system according to this teaching includes a current sensor configured to generate an electrical signal by measuring the AC current flowing through the power system, wherein the current sensor has a measurement dynamic range (e.g., ±V). dyn Current sensors facilitate the measurement of AC current flowing through a power system, for example, to monitor the output current of the power system. A current sensor can be implemented, for example, in a line at the output of the power system (e.g., in an output line). The current sensor can be any type of current sensor; for example, the signal generated by the current sensor can be a voltage signal representing the measured current.

[0011] The current sensor has a given measurement dynamic range (e.g., ±V). dynThe dynamic range can be defined, for example, as the range through which the output signal of a current sensor is readable. For instance, the dynamic range can be the range through which the output signal has a defined relationship with the AC current (e.g., gain). As another example, the dynamic range can be the range through which the output signal is proportional to the AC current. In practical sensors, the dynamic range limits are defined, for example, by the supply voltage of the sensor circuitry, through which the sensor or sensor circuitry is powered. Typically, for a given application, the dynamic range and sensitivity (e.g., resolution) of a current sensor are selected such that the rated operating current level can be observed within the limits of the dynamic range. In other words, for a current sensor, the range of variation of the nominal operating AC current should be readable within the limits of the dynamic range. For power systems that also need to handle large peak currents, this may result in either of two scenarios: first, selecting a current sensor that can measure the highest peak current within the limits of the dynamic range; or second, selecting a current sensor that can measure the rated level of the operating current within the limits of the dynamic range. In the first case, the problem may be that the sensor's dynamic range is not being used effectively for the nominal operating range. This can also reduce the resolution of the nominal operating current (e.g., the ability to detect small changes). The larger the peak current compared to the operating current, the more severe the problem. In the second case, the problem might be that the current sensor output will not provide visibility of the peak current (e.g., due to sensor saturation or clipping of the sensor output). This teaching can overcome these limitations, including limitations for various types of output voltages, where the load current value may change when different output voltages are selected, even if the output power provided is the same.

[0012] Therefore, for example, a large current occurring in the boost mode of a power system, when starting an electrical load such as a rotary tool, if the sensor has a dynamic range limited by the nominal operating current limit, the peak current flowing through the power system is outside the measurement dynamic range of the current sensor.

[0013] According to some embodiments, the protection circuit also includes a rectifier module configured to generate a pulsating DC signal in response to an electrical signal. The electrical signal (particularly an AC signal) from the current sensor is rectified by the rectifier module for subsequent signal processing.

[0014] The protection circuit also includes a superposition module operable to generate an extended signal; wherein the pulsating DC signal is below a predetermined value (e.g., V0). p During the duration of the event, the extended signal is equal to or tracks the pulsating DC signal, and wherein the pulsating DC signal is at or above a predetermined value (e.g., V). p During the duration of ), the extended signal has a preselected value (e.g., V). sFor example, a predetermined value (e.g., V). p ) is at or below the boundary of the measurement dynamic range (e.g., V) dyn In some non-restrictive aspects, the preselected value (e.g., |V) s The value of | is higher than a predetermined value (e.g., |V) p The size of |). For example, when the value is positive, the preselected value (e.g., V) s It can be higher than the predetermined value (e.g., V). p ).

[0015] The purpose of the superposition module is to generate a signal for further signal processing when the output signal of the current sensor is at or above the limits of the current sensor's dynamic range. Therefore, the superposition module allows the creation of a signal (e.g., an extended signal) that contains information about the duration of the current sensor output outside certain limits (e.g., dynamic range). This can be helpful when the AC current flowing through the power system is higher than the current sensor's measurement dynamic range and the electrical signal cannot be relied upon. When the AC current is outside the dynamic range, other components downstream of the current sensor may "ignore" the actual value of the AC current. Therefore, when such a high amplitude of the electrical signal is at or above a predetermined value (e.g., V0), the superposition module generates a signal for further signal processing. P In the case of ), the pulsating DC signal is determined by a preselected value (e.g., V). s ) instead. Pre-selected value (e.g., V) S This could be a value corresponding to the current sensor's value exceeding the measurement dynamic range. In the case of a low amplitude pulsating signal, the extended signal remains equal to the pulsating signal. Therefore, if the pulsating DC signal has an amplitude below a predetermined value, the pulsating DC signal remains unchanged through the superposition module.

[0016] The protection circuit may also include a low-pass filter configured to shape the extended signal to generate a band-limited signal. The low-pass filter may have a time constant (e.g., τ).

[0017] In addition, the protection circuit may include a logic module operable to detect when a band-limited signal violates a predetermined threshold (e.g., V). th A trip signal is generated when AC current is interrupted, thereby ensuring the safety of the power system.

[0018] The logic module may include, for example, a threshold voltage (e.g., V). th At least one comparator. If the band-limited signal exceeds the threshold voltage, the generated trip signal will cut off the current flowing through the power system, and the power system will be set to a safe state.

[0019] Therefore, the aforementioned protection circuit functions as an adjustable circuit breaker. Based on the corresponding output voltage and its associated output current, the current-time characteristics of the protection circuit can be adjusted to support situations requiring high peak currents to connect loads connected to the power system's output. This ensures the safety and reliability of the power system by preventing damage caused by excessive current. The protection circuit also replaces the function of the tripping point of a traditional circuit breaker with the possibility of actively disconnecting the power system.

[0020] The aforementioned settings can be adjusted multiple times to form the characteristics of the protection circuit relative to the AC output voltage selected at the power system output, in terms of current flow that varies over time.

[0021] For example, the following settings can be made to reflect different AC output voltages: - The predetermined value of the superposition module (e.g., V) p ), - Pre-selected values ​​for the overlay module (e.g., V) s ), - The settings of the low-pass filter, especially the time constant (e.g., τ). - The predetermined threshold of the logic module (e.g., V) th ).

[0022] Depending on the selected value, the current-time characteristics of the protection circuit can be tuned. The predetermined value of the superimposed module (e.g., V) p The settings can be configured to create a steeper current-time characteristic for small time values ​​and large currents. The time constant of the low-pass filter and the predetermined threshold V of the logic module are also considered. th The combination settings are primarily for shaping curves with medium to large time values ​​and small currents.

[0023] In a non-limiting embodiment, the protection circuit includes at least two cascaded low-pass filters. The first low-pass filter is particularly a single-pole (e.g., first-order) low-pass filter, followed by at least one second low-pass filter (e.g., a single-pole low-pass filter). For example, the first low-pass filter may have a longer time constant than the second low-pass filter (e.g., ...). Smaller time constant (e.g., In this cascaded arrangement, at least one additional low-pass filter also processes the signal (e.g., a band-limited signal) in the cascaded path.

[0024] In some cases, the protection circuit may include multiple (e.g., plural) low-pass filters. Preferably, at least some of the multiple low-pass filters are connected in parallel. For example, a first low-pass filter may be connected in series with each of the other low-pass filters. This arrangement of multiple low-pass filters allows for more precise tuning of the characteristics of the protection circuit.

[0025] Each low-pass filter can be defined by a time constant (e.g., ...). Characterization. In some embodiments, the time constants of multiple low-pass filters are selected in such a way that the time constant of another low-pass filter (e.g., ) is greater than the time constant of the previous low-pass filter (e.g., For example, in the case of cascading, the first low-pass filter can have the smallest time constant (e.g., Furthermore, the additional low-pass filter can have a time constant greater than that of the first low-pass filter (e.g., > 10 ... ).

[0026] In another non-limiting embodiment, it is operable to respond when a band-limited signal violates a predetermined threshold (e.g., V). th The logic module that generates a trip signal when a circuit breaker is activated includes at least one comparator. The comparator is operable to compare a band-limited signal with a predetermined threshold (e.g., V). th The comparison is performed in response to a band-limited signal violating a threshold (e.g., V). th This generates a trip signal.

[0027] For example, a logic module may include at least two comparators, wherein a predetermined threshold (e.g., V) of another comparator th,i+1 The voltage may be different from (e.g., lower than) the threshold voltage of the previous comparator (e.g., V). th,i ).

[0028] In some non-limiting embodiments, at least two of the comparator outputs are processed via a logical OR operation. For example, for any one or more comparators that detect a violation of their respective predetermined thresholds (e.g., V...), ... th In cases where a trip signal is generated, the power system is brought to a safe state, for example, by interrupting the flow of current through the power system.

[0029] In some non-limiting embodiments, multiple low-pass filters and multiple comparators are connected in such a way that each low-pass filter is connected to its corresponding comparator (e.g., each low-pass filter provides its output at the input of its corresponding comparator). The protection circuit may have the same number of low-pass filters as the comparators. For example, low-pass filters and their corresponding comparators are paired such that a low-pass filter with a smaller time constant (e.g., τ) is connected to a low-pass filter with a larger predetermined threshold (e.g., V). th The comparator. It should be understood that this and similar arrangements can be used to generate the desired characteristics of the circuit breaker within the operating range. This can be used to generate a trip signal that reflects aspects of the current amplitude and duration, thereby allowing limits or tolerances to be set for specific amplitude and duration values ​​of the current, which can be tolerated without triggering the trip signal.

[0030] It should be understood that several or all comparators can be connected in a logical OR configuration using one or more OR gates to implement a tripping curve that reflects the current-time relationship of the current. For example, a two-input OR gate (implemented in hardware or software) can be arranged such that it receives a first input from the comparator and a second input via the output of the preceding OR gate. Thus, at least some of the OR gates can be connected in such a serial OR configuration. For a single OR gate, the logic may need to have the same number of inputs as the comparator. However, any particular kind of OR logic implementation is not limited to the generality or scope of this teaching.

[0031] Alternatively or in combination, the protection circuit may include a limit detector operable to detect when a pulsating DC signal is at or above a predetermined value. The limit detector can compare the pulsating DC signal to the predetermined value and allow the overlay module to process the pulsating DC signal (e.g., when the pulsating DC signal is at or above a pre-selected value (e.g., V0)). S The predetermined threshold (e.g., V) P (in the case of)

[0032] In some embodiments, a predetermined value (e.g., V) P It can be at or below (e.g., just below) the limits of the measurement dynamic range. For example, this can ensure that high currents flowing through the power supply unit are handled as needed by protection circuitry.

[0033] As discussed, when the amplitude of the pulsating DC signal exceeds a predetermined value (e.g., V), P In the case of replacing the preselected value of the pulsating DC signal (e.g., V), sThe preselected value is greater than the limits (e.g., boundaries) of the measurement dynamic range. For example, the preselected value may be at least twice or at least five times higher than the boundaries (e.g., upper limits) of the measurement dynamic range. The preselected value may be higher than the maximum measurement output of the current sensor. However, it should be understood that there may or may not be a correlation between the limits of the measurement dynamic range and the preselected value. Therefore, the preselected value can be any large value outside the dynamic range. The preselected value can also be selected based on one or more parameters (e.g., the time constant of the low-pass filter to which the extended signal is fed) to obtain a specific current-time characteristic of the protection circuit (e.g., the "hockey stick" portion of the time response of the protection circuit).

[0034] It should be understood that some or all of the modules or components discussed herein can be implemented in hardware and / or software, but are not limited to. For example, any, some or all of the rectifier module, superposition module, low-pass filter, and / or logic module can be implemented at least partially in digital form (e.g., as an algorithm or software, such as embedded code). Additionally or alternatively, the limit detector module can be implemented at least partially in digital form. The software implementation of the modules allows for flexibility in the current-time characteristics of the individual components and / or protection circuits during power system operation (e.g., runtime adjustment characteristics). Appropriate settings can be adapted and / or selected according to the operating mode (e.g., the power system should operate in a selected voltage domain (e.g., 220 V AC, 120 V AC, or any other)).

[0035] Additionally or alternatively, any part (e.g., rectifier module, superposition module, low-pass filter, logic module and / or limit detector module) may be implemented at least partially in hardware form (e.g., as a circuit).

[0036] This instruction is particularly useful for power systems with multiple energy storage batteries, AC outputs and AC inputs, and protection circuits as described above, wherein the voltage at the AC output is variable (e.g., it can operate in multiple AC domains, such as 220 V AC, 110 V AC, etc.).

[0037] This teaching can also provide a method for overcurrent protection of power systems with AC output, particularly using a protection circuit as disclosed herein, the method comprising: - A current sensor is used to measure the AC current flowing through the power system and generate an electrical signal in response, wherein the current sensor has a measurement dynamic range; - Rectify the electrical signal to provide a pulsating DC signal (e.g., in response to processing the electrical signal using a rectifier module). - An extended signal is generated using an overlay module; wherein, during the duration when the pulsating DC signal is below a predetermined value, the extended signal is equal to or tracks the pulsating DC signal, and wherein, during the duration when the pulsating DC signal is at or above (e.g., above) a predetermined value, the extended signal has a preselected value; - A band-limited signal is generated by shaping the extended signal using a low-pass filter; - A trip signal is generated when the band-limited signal violates a predetermined threshold (e.g., by evaluation using a logic module); wherein the trip signal can be used to cut off the flow of AC current, thereby putting the power system in a safe state.

[0038] For the advantages and features associated with this method, refer to the description of the system.

[0039] This teaching also relates to a software product comprising instructions that, when executed by a suitable computer processor, cause the processor to perform the method steps described above.

[0040] Further embodiments are illustrated with reference to the following figures, which illustrate certain aspects of this teaching by way of example.

[0041] Displayed in: Figure 1 This is a block diagram of the protection circuit. Figure 2 This is a graph showing the changes in AC current and electrical signal over time in the first operating mode of the power system. Figure 3 It is a graph showing the changes in electrical signals and extended signals over time based on the first operating mode of the power system. Figure 4 It is an extended signal based on the first operating mode of the power system (which is based on) Figure 3 The graph shows the time-varying threshold voltages of band-limited signals and logic modules. Figure 5 This is a graph showing the changes in AC current and electrical signal over time in the second operating mode of the power system. Figure 6 It is a graph showing the time variation of the pulsating DC signal and the extended signal based on the second operating mode of the power system. Figure 7 It is based on the extended signal of the second operating mode of the power system (which is based on) Figure 6 The graph shows the time-varying threshold voltages of band-limited signals and logic modules. Figure 8 This is a graph showing the changes in the characteristics of a standard circuit breaker and the resulting circuit breaker voltage characteristics over time. Figure 9 This is a flowchart of a method for overcurrent protection.

[0042] Figure 1 A block diagram of a protection circuit 10 for a power system 12 is depicted.

[0043] Figures 2 to 7 This is a diagram showing the different signals obtained at the outputs of different components of the protection circuit 10.

[0044] Power system 12 is capable of supplying, for example, temporary off-grid power to a load. In order to connect power system 12 to a tool, power system 12 includes two-pole output 14. It should be understood that in some power domains, without any limitation on the general scope of this teaching, N (16) and L (18) may be referred to as L1 and L2, or any other name.

[0045] In order to measure the AC current flowing through the power system 12, the protection circuit 10 includes a current sensor 20, which is arranged in a straight line with either of the conductors 16 or 18 (in this example, the so-called phase conductor 18).

[0046] The current sensor 20 is arranged to measure the AC current 36 flowing through the power system 12 (see example). Figure 2 ) to generate electrical signal 38 (see example) Figure 2 The current sensor 20 has a measurement dynamic range (e.g., ±V). dyn ). Measure dynamic range (e.g., ±V) dyn In the example shown, they are located at ±240 A and ±2.4 V respectively (see example). Figure 2 In other words, using this non-limiting example, for a current 36 that varies by ±240 A, the current sensor 20 provides an electrical signal 38 located between ±2.4 V. Therefore, the value of the current 36 at ±240 A can be read via the current sensor 20, and the electrical signal 38 varies accordingly by ±2.4 V.

[0047] Connected to the output of the current sensor 20 is a rectifier module 22, which is operable to generate a pulsating DC signal 40 in response to the electrical signal 38 (see...). Figure 6 ).

[0048] The rectifier module 22 is connected to the superposition module 24, which is operable to generate an extended signal 42 (see example). Figure 3 When the pulsating DC signal is below the predetermined value V. P During the duration, the extended signal 42 is equal to or tracks the pulsating DC signal 40, and wherein, when the pulsating DC signal 40 is at or above a predetermined value V... P During its duration, the extended signal 42 has a preselected value V S In this example, the predetermined value V PThe selected value is 2.2 V, which is below the measurement dynamic range of the current sensor 20. Preselected value V s In this example, it is set to 15 V.

[0049] The extended signal 42 is used as the input to the first low-pass filter 26a, which is operable to shape the extended signal 42 to generate the band-limited signal 44.

[0050] The first low-pass filter 26a is cascaded with it, and optionally, multiple low-pass filters 26b-26j are arranged in parallel. Here, nine low-pass filters 26b-26j are connected in parallel and cascaded to the first low-pass filter 26a.

[0051] Low-pass filters 26a to 26j are linked to logic module 28, which is operable to detect when the band-limited signal 44 violates a predetermined threshold V. th A trip signal is generated in time. Logic module 28 includes multiple comparators 30a-30j, each comparator 30a-30j is linked to a low-pass filter 26a-26j.

[0052] Comparators 30a-30j are linked via logical OR operator 32, which demonstrates one way to implement the OR function using a two-input OR gate.

[0053] In the example shown, the following values ​​have been used for low-pass filters 26a-26j and the corresponding comparators 30a-30j:

[0054] The generated trip signal can be used to interrupt the flow of AC current 36. The logic unit is connected to switch 34 to interrupt the AC current flowing through power system 12, thereby putting power system 12 into a safe state.

[0055] With the help of Figures 2 to 7 The basic functions of the different modules of the protection circuit 10 are explained.

[0056] Figures 2 to 4 The diagram relates to the operating mode curves of power system 12, wherein the AC current 36 at the output terminal 14 of power system 12 does not exceed the measurement dynamic range V of current sensor 20. dyn .

[0057] Figure 2 The AC current 36 flowing through the power system 12 is shown. The AC current 36 has a maximum amplitude of 220 A. The maximum amplitude of the AC current 36 corresponds to the value of the electrical signal 38, which is slightly below the measurement dynamic range V of the current sensor 20. dynThe 2.4 V boundary. Although the example here shows the sensor dynamic range in volts, other kinds of outputs (e.g., any other physical parameters such as current, impedance, or combinations thereof) are also possible, which can be used directly or via conversion to volts.

[0058] therefore, Figure 2 The generated electrical signal 38 from the current sensor 20 is depicted when observed in relation to the AC current 36. In this example, the relationship between the AC current 36 and the generated electrical signal 38 is proportional within the dynamic range of the current sensor 20.

[0059] Figure 3 The diagram shows a combination of the electrical signal 38 generated by the current sensor 20 and the extended signal 42 generated by the superposition module 24. The pulsating DC signal generated by the rectifier module 22 is not shown here because, in this case, the value of the electrical signal 38 does not reach the limit of the measurement dynamic range. It should be understood that, in this case, the extended signal 42 and the pulsating DC signal 40 will be identical. A predetermined value V plotted at 2.2 V is also shown. P When the amplitude of electrical signal 38 (and the pulsating DC signal) remains at the predetermined value V P In the following case, the extended signal 42 follows the pulsating DC signal (the latter is not shown here).

[0060] Figure 4 The extended signal 42 is depicted on a longer time scale. After the extended signal 42 passes through a first low-pass filter 26a with a time constant τ, a band-limited signal 44 is obtained from the output of the extended signal 42. Threshold voltage V th The first comparator 30a of logic module 28 is set to V th =1.37 V.

[0061] As from Figure 4 It can be observed that when the amplitude of the band-limited signal 44 exceeds the threshold voltage V th At that time, logic module 28 can be operated to generate a trip signal after approximately 9.5 ms.

[0062] Figures 5 to 7 The operating mode of the power system 12 is shown, in which the amplitude of the actual flowing AC current 36 exceeds the measurement dynamic range V of the current sensor 20. dyn .

[0063] Figure 5 An AC current 36 flowing through the power system 12 is depicted. The AC current 36 has an amplitude of 500 A, which exceeds the boundary of the measurement dynamic range of the current sensor 20, which has a V corresponding to an amplitude of 240 A. dyn .

[0064] also, Figure 5 The electrical signal 38 from the current sensor 20 is shown. The relationship between the AC current 36 and the generated electrical signal 38 is no longer proportional for higher amplitudes, causing clipping of the electrical signal 38 from the current sensor 20, exceeding the boundary of the 2.4 V measurement dynamic range.

[0065] Figure 6 The pulsating DC signal 40 generated from the electrical signal 38 is shown. Figure 6 An extended signal 42 obtained by processing the pulsating DC signal 40 via the superposition module 24 is also shown. To generate the extended signal 42, the pulsating DC signal 40 is at or above a predetermined value V. P During the duration, the pulsating DC signal 40 is preselected by value V. s Instead. Otherwise, the extended signal 42 is equivalent to the pulsating DC signal 40.

[0066] As can be seen in this example, the preselected value V s The size is higher than the predetermined value V p The size; or simply put, the preselected value V s Higher than the predetermined value V p In this case, the predetermined value V P It was set to 2.2V, which is slightly below the measured dynamic range V. dyn The boundary value is 2.4V. In this example, the preselected value V S It is set to 15 V.

[0067] Figure 7 The extended signal 42 is depicted, now on a longer time scale. The band-limited signal 44 is also shown. (The last sentence appears to be incomplete and possibly refers to a different signal.) =31.2 ms The first low-pass filter 26a generates a band-limited signal 44 and Figure 4 The band-limited signal rises faster in the operating mode within the range. The threshold voltage is set to V by the first comparator 30a of logic module 28. th =1.37V.

[0068] If possible Figure 7 As can be seen, logic module 28 is operable to respond when the band-limited signal 44 exceeds the threshold voltage V. th A trip signal is generated, which in this case occurs at approximately 4 ms.

[0069] Figure 8This is a graph using curves 46 and 48 to illustrate specific characteristics of the circuit breaker. Current is plotted on the y-axis, and time on the x-axis. For any value below the value of the bottom curve 46 (any coordinate on the graph shown between the axis and curve 46), the circuit breaker should not trip, while for any value above the value of the top curve 48 (any coordinate on the graph shown separated from the axis by curve 48), tripping must occur. Therefore, curve 46 can delineate a safe area where the power system 12 can operate without tripping the system. Similarly, curve 48 can delineate restricted areas to prevent damage to the power system 12 and / or any associated electrical loads and / or power supply equipment. The area between the two curves 46 and 48 can be a hysteresis zone, where tripping may be tolerable but not necessary. It is understood that the upper curve 48 has a more critical function compared to the lower curve 46. The upper curve 48 is more safety-critical, while the lower curve 46 is more operation-range-related. It may be desirable to achieve the characteristics of curve 48 via protective elements (e.g., thermal fuses, etc.), which provides more last-line protection. These elements can sometimes be more difficult to replace if they are built-in or if the user needs to purchase them or keep them in stock. Therefore, circuit breakers may be more suitable for temporary tripping that can be more easily reset by the user. Thus, the proposed protection circuit 10 can be implemented to simulate the desired characteristics, providing a first or even second level of protection (e.g., if the first level is a conventional circuit breaker) before the final protective element based on curve 48 is triggered. Therefore, this teaching not only achieves better safety and reliability from a security perspective but also potentially enhances end-user usability by preventing situations that lead to the triggering of the final protective element.

[0070] Example characteristics of protection circuit 10 are plotted using curve 50. Curve 50 has a steep slope for small times and high currents, which is mainly affected by the predetermined value V. P The impact.

[0071] Curve 50 illustrates several segments 52 (52a to 52d), of which only four segments are highlighted here. The curve in each segment is composed of low-pass filters 26a–26j with a time constant τ and a predetermined threshold V. th The corresponding comparators 30a–30j are combined to shape the shape.

[0072] For multi-mode operation (e.g., operation at different voltages), protection circuit 10 may include components for automatic adaptation feature 50 to provide reliable protection in any mode. Components for the adaptation feature may include: one or more lookup tables, pre-stored values ​​selected based on a specific mode, logic units with weights that specify thresholds for the comparator, the like, or combinations thereof.

[0073] From another perspective, a software product including instructions (e.g., embodied on a non-transitory computer storage medium) may also be provided, which, when executed by a suitable computer processor or a system including suitable components, cause the computer processor or system to perform the methods described herein (e.g., the method steps for performing the methods described herein).

[0074] Figure 9 A flowchart of a method for overcurrent protection of power system 12 is shown.

[0075] In step S1, the method begins and the power system 12 is switched on.

[0076] In step S2, the AC current 36 flowing through the power system 12 is measured using the current sensor 20, and an electrical signal 38 is generated in response, wherein the current sensor 20 has a measurement dynamic range.

[0077] Next, in step S3, a pulsating DC signal 40 in response to the electrical signal 38 is generated via the rectifier module 22.

[0078] In step S4, it is checked whether the pulsating DC signal 40 is lower than a predetermined value (e.g., V). p ).

[0079] If it is determined in step S4 that the pulsating DC signal 40 is lower than a predetermined value (e.g., V), P If y = yes, then in step S5, an extended signal 42 is generated via the superposition module 24. The extended signal 42 generated in S5 is equal to or tracks the pulsating DC signal 40.

[0080] If it is determined in step S4 that the pulsating DC signal 40 is at or above a predetermined value (e.g., V), P If n=no, then in step S6, an extended signal 42 is generated via the superposition module 24. The extended signal 42 generated in S6 has a preselected value V. s Therefore, for the time when the pulsating DC signal 40 is below the predetermined value, the output of S5 can be provided in step S7; while for the time when the pulsating DC signal 40 is at or above the predetermined value, the output of S6 can be provided in step S7.

[0081] In step S7, a band-limited signal 44 is generated via at least one low-pass filter 26a to shape the extended signal 42. For example, the extended signal 42 provided at S7 for shaping may be the output of S5 or the output of S6.

[0082] In step S8, the logic module 32 checks whether the band-limited signal 44 violates a predetermined threshold (e.g., V). th ).

[0083] If it is determined in step S8 that the band-limited signal 44 violates a predetermined threshold (e.g., V), th If y = yes, then in step S9, a trip signal is generated via logic module 28. The trip signal can be used to put the power system 12 into a safe state, for example by cutting off the flow of AC current 36.

[0084] If it is determined in step S8 that the band-limited signal 44 does not violate a predetermined threshold (e.g., V), th If (n=no), then the method can return to step S2 to continue monitoring the power system 12.

[0085] List of reference numerals

[0086] 10. Protection Circuit

[0087] 12 Power System

[0088] 14 Electrical output

[0089] 16 conductors

[0090] 18 conductors

[0091] 20 Current Sensor

[0092] 22 Rectifier Module

[0093] 24 stacking modules

[0094] 26a-j low-pass filter

[0095] 28 Logic Modules

[0096] 30a-j comparator

[0097] 32. Logical OR operator

[0098] 34 Switches

[0099] 36 AC current

[0100] 38 Electrical signals

[0101] 40 Pulsating DC Signal

[0102] 42 Extended Signal

[0103] 44 band limited signal

[0104] 46 Lower limit

[0105] 48 (maximum)

[0106] 50. Current-time characteristics of protection circuits

[0107] Sections 52a-52d

[0108] Although embodiments or aspects have been described in detail for illustrative purposes, it should be understood that such details are for that purpose only, and this disclosure is not limited to the disclosed embodiments or aspects, but rather is intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it should be understood that this disclosure contemplates that, to the extent possible, one or more features of any embodiment or aspect may be combined with one or more features of any other embodiment or aspect. Aspects that may have been discussed in this disclosure with reference to product categories may also be combined with method categories, and vice versa.

[0109] For descriptive purposes, the terms “end,” “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and their derivatives should refer to embodiments oriented as they are in the accompanying drawings. However, it should be understood that this disclosure may take various alternative variations and sequences of steps unless expressly stated otherwise. The terms “first,” “second,” or “third,” etc., have been used to establish references to corresponding features. For the purposes of the scope of this teaching, saying “first” or “second” does not imply that a particular feature must be added in a particular order or sequence to be effective. It should also be understood that the specific apparatus and processes shown in the accompanying drawings and described in the following specification are merely examples and non-limiting embodiments or aspects of the disclosed subject matter. Therefore, specific dimensions and other physical characteristics associated with the embodiments or aspects disclosed herein should not be considered limiting.

[0110] Unless explicitly stated otherwise, no aspect, component, element, structure, action, step, function, instruction, etc., as used herein should be construed as critical or necessary. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more” and “at least one.” Additionally, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.) and may be used interchangeably with “one or more” or “at least one.” The term “an” or similar language is used when referring to only one item. Furthermore, as used herein, the terms “having,” “possessing,” “containing,” etc., are intended to be open-ended terms. Furthermore, unless explicitly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.” Additionally, a reference to an action based on a condition can mean that the action is “in response to” the condition. For example, in some non-limiting embodiments or aspects, the phrases “based on” and “in response to” can refer to a condition for automatically triggering an action (e.g., specific operation of an electronic device such as a computing device, processor, etc.).

Claims

1. A protection circuit for protecting a power system, wherein, The protection circuit includes: - A current sensor operable to generate an electrical signal by measuring the AC current flowing through the power system; wherein the current sensor has a measurement dynamic range; - A rectifier module operable to generate a pulsating DC signal in response to the electrical signal; - An overlay module operable to generate an extended signal; wherein, during a duration when the pulsating DC signal is below a predetermined value, the extended signal is equal to or tracks the pulsating DC signal, and wherein, during the duration when the pulsating DC signal is at or above the predetermined value, the extended signal has a preselected value; - A low-pass filter configured to shape the extended signal to generate a band-limited signal; - A logic module configured to generate a trip signal when the band-limited signal violates a predetermined threshold; wherein the trip signal can be used to cut off the flow of the AC current, thereby putting the power system in a safe state.

2. The protection circuit according to the preceding claim, wherein, The size of the preselected value is higher than the size of the predetermined value.

3. The protection circuit according to any one of the preceding claims, wherein, The predetermined value of the superposition module, the pre-selected value of the superposition module, the time constant of the low-pass filter, and / or the predetermined threshold are selectable according to the operating mode of the power system, for example, operating in a selected voltage output domain.

4. The protection circuit according to any one of the preceding claims, wherein, The protection circuit includes at least two cascaded low-pass filters.

5. The protection circuit according to any one of the preceding claims, wherein, The protection circuit includes multiple low-pass filters.

6. The protection circuit according to any one of claims 3 to 4, wherein, Each low-pass filter has a different time constant, and the time constant of another low-pass filter is greater than the time constant of the previous low-pass filter.

7. The protection circuit according to any one of the preceding claims, wherein, The logic module includes at least one comparator.

8. The protection circuit according to any one of the preceding claims, wherein, The logic module includes at least two comparators, wherein the predetermined threshold of the other comparator is lower than the predetermined threshold of the previous comparator.

9. The protection circuit according to the preceding claim, wherein, The outputs of at least two comparators are linked together using a logical OR operation.

10. The protection circuit according to any one of the preceding claims, wherein, The limit detector module is configured to detect when the pulsating DC signal is at or above the predetermined value.

11. The protection circuit according to any one of the preceding claims, wherein, The predetermined value is lower than the limit value of the measurement dynamic range.

12. The protection circuit according to any one of the preceding claims, wherein, The preselected value is greater than the limit value of the measurement dynamic range.

13. The protection circuit according to any one of the preceding claims, wherein, The rectifier module, the superposition module, the low-pass filter, and / or the logic module are implemented at least partially in the digital domain (e.g., software).

14. A method for overcurrent protection in a power system, the method comprising: - A current sensor is used to measure the AC current flowing through the power system and generate an electrical signal in response, wherein the current sensor has a measurement dynamic range; - In response to the electrical signal, a pulsating DC signal is generated via a rectifier module; - An extended signal is generated via an overlay module; wherein, during the duration during which the pulsating DC signal is below a predetermined value, the extended signal is equal to or tracks the pulsating DC signal, and wherein, during the duration during which the pulsating DC signal is at or above the predetermined value, the extended signal has a preselected value; - A band-limited signal is generated via a low-pass filter to shape the extended signal; When the band-limited signal violates a predetermined threshold, a trip signal is generated via a logic module; wherein the trip signal is used to cut off the flow of the AC current, thereby putting the power system in a safe state.

15. A software product comprising instructions that, when executed by a suitable computer processor, cause the processor to perform the steps of any of the preceding method claims.

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