Protection circuit for a device or power circuit breaker

Abstract

comprising a protective circuit (1) for a device or power circuit breaker, • an active controllable component (B1) which can be controlled in a linear range, • at least one measuring device (S P , S U , S i , S Uin , S Uout ) to determine a power output that is implemented in the actively controllable component (B1), • a processing unit (uC), • where an energy equivalent can be determined based on the specified power and a time between two measurements, • where time-separated energy equivalents are combined by the processing unit (uC), • where at least two time-related limit values ​​(G t1 , G t2 , ... G tn ) are planned, • where, upon reaching and / or exceeding a limit value (G t1 , G t2 , ... G tn) by an energy equivalent or the combined energy equivalents in a limit value (G t1 , G t2 , ... G tn ) assigned time the active controllable component (B1) is controlled by the processing unit (uC) in such a way that the current flow through the active controllable component (B1) is reduced or prevented.

Description

background

[0001] Current-limiting or current-switching elements can be found in many areas of electrical systems and devices.

[0002] One purpose of such elements can be, for example, to protect parallel-connected electrical devices from voltage dips, such as those that could occur when a device draws more current. Such situations can arise, for example, in the event of a short circuit, when large capacitive loads need to be charged, or more generally, when a new device is added.

[0003] If no protective measures are taken, unexpected disturbances, malfunctions, or even damage can occur, not only in the affected device itself, but also in other consumers located in the same supply network.

[0004] Electronic device or circuit breakers are often used to limit or cut off the current to the power-consuming device.

[0005] These electronic device or power protection switches generally use an active component that is typically in linear operation.

[0006] In current-limiting operation, electrical power is converted into thermal power in the active component.

[0007] If the power output exceeds a certain level, permanent damage to the active component can occur.

[0008] Manufacturers of active components therefore specify corresponding characteristic curves in datasheets, in the case of MOSFETs the so-called SOA characteristic curve (Safe Operating Area).

[0009] These characteristic curves are included in a worst-case analysis and used for the design to guarantee the safe operation of the component. For the worst-case analysis, the maximum (rated) operating voltage is generally used, since in the event of a short circuit, (almost) the entire operating voltage is applied to the active component. Depending on the limited current, the maximum time during which the component may be operated linearly is determined.

[0010] While this approach ensures safe operation, it leads to limitations in normal operating characteristics. In particular, charging larger capacitive loads or, more generally, operation in non-constant states becomes more difficult or even impossible. Task

[0011] Based on this, one object of the invention is to provide an improvement that allows safe operation to be guaranteed and also restricts the characteristics of normal operation less. Brief description of the invention

[0012] The problem is solved by a protective circuit for a device or power circuit breaker according to claim 1. Further advantageous embodiments are the subject of the dependent claims, the description and the figures. Brief description of the characters

[0013] The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way.

[0014] They show: Fig. 1 Views of a circuit breaker according to embodiments of the invention, Fig. 2 an exemplary flowchart according to embodiments of the invention, Fig. 3 a further exemplary flowchart according to embodiments of the invention, and Fig. 4 an example SOA diagram. Detailed description of the invention

[0015] The invention will now be described in more detail with reference to the figures. It should be noted that different aspects are described, each of which can be used individually or in combination. That is, each aspect can be used with different embodiments of the invention, unless explicitly presented as a pure alternative.

[0016] Furthermore, for the sake of simplicity, reference will generally be made to only one entity at a time. Unless explicitly stated otherwise, the invention may also include several of the entities concerned. Therefore, the use of the words "a," "an," and "one" should only be understood as an indication that at least one entity is used in a simple embodiment.

[0017] Information with numerical values ​​should generally not be understood as exact values, but also include a tolerance of + / - 1% to + / - 10%.

[0018] Insofar as standards, specifications, or the like are mentioned in this application, reference is always made to at least those standards, specifications, or the like applicable on the filing date. That is to say, if a standard / specification, etc., is updated or replaced by a successor, the invention is also applicable to it.

[0019] Unless otherwise stated, circuit breakers are in particular compliant with DIN EN IEC 60934 VDE 0642:2020-11.

[0020] In one embodiment of the invention, a protective circuit 1 is provided for a device or power circuit breaker.

[0021] Without claiming to be exhaustive, this protection circuit 1 includes an active controllable component B1, which can be controlled within a linear range. Furthermore, the protection circuit 1 includes at least one measuring device S. P , S U , S i , S Uin , S Uout to determine a power output that is implemented in the actively controllable component B1, and a processing unit uC.

[0022] "Determination" is to be understood broadly and can include direct measurement, indirect measurement, reading from a characteristic map, calculation, etc., and possibly further processing steps. A measurement can be taken on the actively controllable component B1 itself, or on other elements. The essential point is that, in the end, a statement about the power delivered by the actively controllable component B1 is provided.

[0023] Based on the determined power(s) and a time between two measurements, an energy equivalent can be determined, whereby time-separated energy equivalents are summarized by the processing unit uC.

[0024] Without limiting the generality, summarizing includes both the evaluation of individual values ​​and the further processing of previous values. For example, further processing can include the digital implementation of transmission elements.

[0025] For further processing, at least two time-related limit values ​​G are required. t1 , G t2 , ... G tn provided for, whereby upon reaching and / or exceeding a limit value G t1 , G t2 , ... G tn through an energy equivalent or the combined energy equivalents in a limit value G t1 , G t2 , ... G tn During the assigned time, the active controllable component B1 is controlled by the processing unit uC in such a way that the current flow through the active controllable component B1 is reduced or prevented.

[0026] In one embodiment of the invention, the actively controllable component B1 is a semiconductor device, in particular a power semiconductor. For example, the actively controllable component B1 is selected from a group comprising a field-effect transistor, in particular a MOSFET, or an IGBT transistor. This means the invention is applicable to a wide range of devices.

[0027] In a further embodiment of the invention, the determination of energy equivalents is only initiated when a threshold value of a quantity previously measured or calculated for determining power is exceeded. This reduces the computational effort. It also prevents, for example, erroneous shutdowns that could otherwise occur depending on the implementation, e.g., through continuous summation / integration.

[0028] According to a further embodiment of the invention, the determination of energy equivalents can be aborted if a previously measured or calculated quantity used to determine power falls below a certain threshold. This reduces the computational effort.

[0029] In yet another embodiment of the invention, a predetermined value is subtracted from the total energy equivalents, particularly when a previously measured or calculated quantity or energy equivalent falls below a threshold value. This allows, for example, consideration of the fact that the actively controllable component B1 cools down again after a power input. A thermal resistance, for instance, can be taken into account accordingly. If, for example, another monitoring event occurs after a short time, this can also consider the previous monitoring event, depending on the elapsed time, since the total energy equivalents may not yet have returned to zero.

[0030] According to yet another embodiment of the invention, energy equivalents are determined, in particular, periodically. This allows for the provision of a continuous safety function. It also simplifies the use of transfer elements and thus reduces computational effort.

[0031] In yet another embodiment of the invention, the at least one measuring device S P , S U , S i , S Uin , S Uout to determine a performance, • a current measuring device S i , and at least one voltage measuring device S U to determine a voltage across the actively controllable component B1, or • a power measuring device S P However, other configurations are not excluded.

[0032] Without limiting the generality of the invention, in a further embodiment of the invention the voltage across the actively controllable component B1 is determined by the difference of the voltage at input U in of the actively controllable component B1 and at output U out of the actively controllable component B1 is determined.

[0033] Furthermore, in embodiments of the invention, it may be provided that the processing unit uC comprises a microcontroller, a microprocessor, an FPGA, an ASIC, a DSP or the like.

[0034] It can also be provided that the protective circuit according to the invention is part of a device or power circuit breaker.

[0035] The following are exemplary processes based on the Fig. 2 and Fig. 3 described.

[0036] For example, an initialization step 50 may be provided in which, for example, counter variables are set to a predetermined value, e.g., to a combined energy equivalent E(t=0)=0.

[0037] An exemplary sequence for a protective circuit 1 according to the invention for a device or power circuit breaker with an actively controllable component B1, which can be controlled in a linear range, includes a step of determining a power 100, 300 by the actively controllable component B1. For example, this step can be implemented as a single power determination step or as a distributed step. For example, a voltage U can be determined in step 100 and a current I in step 300. Only when both values ​​are available can a power be determined.

[0038] Based on the determined power and a time Δt between two measurements, an energy equivalent can be determined, where time-separated energy equivalents in one step 400, e.g. E(t)=E(t-1)+E Mess =E(t-1)+U*I*Δt, can be summarized.

[0039] As previously described, at least two time-related limit values ​​G t1 , G t2 , ... G tn provided for, whereby upon reaching and / or exceeding a limit value of 500 G t1 , G t2 , ... G tn through an energy equivalent or the combined energy equivalents in a limit value G t1 , G t2 , ... G tn assigned time t1, t2 ... tn the active controllable component B1 is controlled in such a way that the current flow through the active controllable component B1 is reduced or prevented 600.

[0040] In embodiments of the invention, it may be provided that a determination of energy equivalents is only taken up when a limit value of 200 of a quantity previously measured or calculated for the determination of power is exceeded.

[0041] However, in embodiments of the invention it may also be provided that the determination of energy equivalents is aborted if a limit value of a quantity 250 previously measured or calculated for the determination of power is undershot.

[0042] Furthermore, it may also be provided that if a previously measured or calculated quantity or energy equivalent used to determine power falls below a certain threshold, a predetermined value is subtracted from the total energy equivalents. Alternatively, a reset of the total energy equivalents may be provided, e.g., if the time interval between two measurements is so long that the predetermined value to be subtracted would be greater than or equal to the total energy equivalent.

[0043] As mentioned previously, energy equivalents can be determined periodically. For example, a loop back after step 500 can be used for this purpose.

[0044] According to one embodiment of the invention, one step includes determining a power: Determining a voltage across the actively controllable component B1, wherein the difference of the voltage at input U inof the actively controllable component B1 and at output U out of the actively controllable component B1 is determined.

[0045] Without limiting the generality, it can be envisaged that, for example, values ​​from different SOA characteristic curves, e.g., for different times (e.g., 100 µs, 1 ms, 10 ms, 100 ms), are used for the determination. Based on the knowledge of two limit values ​​from the corresponding characteristic curves, limit values ​​for other times can be determined / approximated.

[0046] With the invention, it is now possible to protect parallel connected participants from unwanted voltage dips by limiting the current in the load section to be protected, while at the same time the range of the permissible current can be used more effectively by dynamically adjusting the control / switching condition.

[0047] Instead of determining a time based on given data, it is advantageous to look at individual points of the characteristic curve, e.g. points of equal voltage at different times.

[0048] Each point then provides a relationship for current, voltage, and time.

[0049] The product gives the permissible energy at a time T. ESOA(T)=U⋅I⋅T

[0050] To obtain an energy as a function of time E(t), an approximation between points of the SOA characteristic curve can be used - see, for example, in Fig. 4 - to be carried out. The time reference value T0 is relevant for this. Since the SOA characteristic curve is only valid for linear operation, the time points mentioned in it are also considered from the beginning of linear operation. The time reference value T0 is used for this purpose. As described below, exceeding a limit value can be used to define T0.

[0051] This approximation can be either a step function between the SOA points or an approximation between the known support points.

[0052] It is possible to calculate the energy at the linearly operated component(s).

[0053] In the example shown, for example, input voltage u in , Output voltage U out and current i (step 100, 300) are measured and with their sampling interval T s multiplied and then accumulated with the previous value (step 400).

[0054] It can be stipulated that accumulation only occurs if linear operation is present, e.g., if the voltage in step 200 exceeds a certain limit, for example, only if the difference between u is present in the switched-on state. in and U out a limit U X exceeds.

[0055] If the limit value is exceeded, this can simultaneously be used as a time reference value T0. EMOS(nTs)=EMOS((n−1)⋅Ts)+(uout−uin)⋅Ts for (uout−uin)≥Ux EMOS(nTs)=EMOS((n−1)⋅Ts) for (uout−uin) <Ux

[0056] The observed energy of the component can be compared with the permissible energy per unit of time relative to the reference value T0. If the observed energy is greater than or equal to the permissible energy, linear operation should be discontinued.

[0057] In this example, this can be achieved by switching off the channel or changing the limiting current in step 600.

[0058] If the current is changed, monitoring (not shown) can take place, such that if the actual current falls below the limited current, an energy decrement is carried out analogously to step 275, or the current limit is reset.

[0059] This dynamic energy monitoring allows both supply voltage and load variations to be integrated into the component protection routines. List of designations 1 Protection circuit B1 active controllable component S P , S U , S i , S Uin , S Uout Measuring device microcontroller processing unit G t1 , G t2 , ... G tn Time-related limit values R Shunt , R Last Resistance

Claims

[1] comprising a protective circuit (1) for a device or power circuit breaker, • an active controllable component (B1) which can be controlled in a linear range, • at least one measuring device (S P , S U , S i , S Uin , S Uout ) to determine a power output that is implemented in the actively controllable component (B1), • a processing unit (uC), • where an energy equivalent can be determined based on the specified power and a time between two measurements, • where time-separated energy equivalents are combined by the processing unit (uC), • where at least two time-related limit values ​​(G t1 , G t2 , ... G tn ) are planned, • where, upon reaching and / or exceeding a limit value (G t1 , G t2 , ... G tn) by an energy equivalent or the combined energy equivalents in a limit value (G t1 , G t2 , ... G tn ) assigned time the active controllable component (B1) is controlled by the processing unit (uC) in such a way that the current flow through the active controllable component (B1) is reduced or prevented. [2] Protection circuit (1) according to claim 1, characterized by , that the active controllable component (B1) is a semiconductor device. [3] Protection circuit (1) according to claim 1 or 2, characterized by , that the active controllable component (B1) is a power semiconductor. [4] Protection circuit (1) according to one of the preceding claims, characterized by , that the active controllable component (B1) is selected from a group comprising a field-effect transistor, in particular a MOSFET, or an IGBT transistor. [5] Protection circuit (1) according to one of the preceding claims, characterized by, that a determination of energy equivalents is only taken up when a limit value of a quantity previously measured or calculated for determining power is exceeded. [6] Protection circuit (1) according to claim 5, characterized by , that the determination of energy equivalents is aborted if a limit value of a quantity previously measured or calculated for the determination of power is undershot. [7] Protection circuit (1) according to one of the preceding claims, characterized by , that in particular if a limit value of a quantity or energy equivalent previously measured or calculated for the determination of performance is undershot, a predetermined value is subtracted from the total energy equivalents. [8] Protection circuit (1) according to one of the preceding claims, characterized by that energy equivalents are determined periodically. [9] Protection circuit (1) according to one of the preceding claims, characterized by that at least one measuring device (S P , S U , S i , S Uin , S Uout ) to determine a performance, • a current measuring device (S1), and at least one voltage measuring device (S U ) to determine a voltage across the actively controllable component (B1), or • a power measuring device (S P ) exhibits. [10] Protection circuit (1) according to one of the preceding claims, characterized by , that the voltage across the actively controllable component (B1) is determined by the difference in voltage at the input (U in ) of the actively controllable component (B1) and at the output (U out ) of the actively controllable component (B1) is determined. [11] Protection circuit (1) according to any one of the preceding claims, characterized by that the processing unit (uC) has a microcontroller. [12] Device or power protection switch comprising a protective circuit (1) according to one of the preceding claims.

Images