Method and apparatus for protecting an electrical load from overvoltage

Abstract

A protection device (1) for protecting an electrical load (9), the protection device (1) comprising: at least one input terminal (2) adapted to receive a supply voltage; at least one semiconductor power switch (5) connected in series with the associated input terminal (2) in a supply path (10), an electrical load (9) connected with an output terminal (3) of the supply path (10) receives a load current IL through the supply path; the protection device (1) further comprising: a control unit (8) having a microprocessor (8A) adapted to control a drive circuit (6) of the protection device (1) to turn on or turn off at least one semiconductor power switch (5) arranged in a supply path (10) in response to a received switching command (CMD); the protection device (1) further comprising: at least one overvoltage detection circuit ODC (12) connected with the associated supply path (10) of the protection device (1) and adapted to detect an overvoltage condition at the respective supply path (10) of the protection device (1) and, upon detection of an overvoltage condition by the overvoltage detection circuit ODC (12), directly control the drive circuit (6) through a control line (12, 20) connected with a driver input (IN) of a low voltage side (6A) of the drive circuit (6) to turn off at least one semiconductor power switch (5) arranged within the associated supply path (10) to protect the connected electrical load (9) from an overvoltage.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method and a device for protecting an electrical load connected to an output terminal of a protection device from overvoltages. BACKGROUND

[0002] An overvoltage occurs when the voltage in a part of a circuit or load device rises above an upper design limit. There can be many different situations and conditions in which an overvoltage can occur. Depending on its duration, an overvoltage event can be transient, i.e. the occurrence of a voltage spike, or permanent, resulting in a surge. For example, a lightning strike can cause an overvoltage in a power supply network, which in turn can cause an electrical load connected to the power supply network to be damaged. In addition, voltage spikes can be caused by electromagnetic induction when switching on or off an inductive load, such as an electric motor, or switching a large resistive AC load. Since transient overvoltages, including voltage spikes, can occur, it is necessary to switch off the connected load as quickly as possible to avoid any damage to its internal circuitry. SUMMARY

[0003] It is therefore an object of the present invention to provide a protection device for protecting an electrical load from overvoltages which switches off the connected load in a minimum off-period.

[0004] According to a first aspect of the invention, the above object is achieved by a protection device comprising the features of claim 1.

[0005] According to the first aspect, the invention provides a protection device for protecting an electrical load from overvoltages,

[0006] The protection device comprises:

[0007] at least one input terminal adapted to receive a supply voltage; at least one semiconductor power switch in a supply path, the semiconductor power switch being connected in series with an associated input terminal, an electrical load connected to an output terminal of the supply path receiving an electrical load current through the supply path, wherein the protection device further comprises a control unit CU having a microprocessor, the control unit being adapted to control a drive circuit of the protection device to switch on or off the at least one power switch arranged in the supply path in response to a received switch command,

[0008] wherein the protection device further comprises:

[0009] at least one overvoltage detection circuit ODC connected with an associated power supply path of the protection device and adapted to detect an overvoltage condition at the respective power supply path of the protection device and to directly control the drive circuit to turn off at least one semiconductor power switch provided within the associated power supply path for a short turn-off period by a control line connected with a driver input of the low voltage side of the drive circuit to provide the connected electrical load with protection from overvoltage effects when the overvoltage condition is detected by the overvoltage detection circuit ODC,

[0010] wherein the short turn-off period is predetermined by a control signal propagation delay along the control line and a propagation delay along the internal circuitry of the drive circuit.

[0011] In a preferred embodiment, the protection device according to the first aspect of the present application is capable of turning off at least one semiconductor power switch within the power supply path for a turn-off period of less than 1 millisecond. This is possible because the propagation delay of the internal circuitry of the drive circuit is less than 200 nanoseconds.

[0012] In a preferred embodiment, the overvoltage detection circuit comprises a fast analog control path with a minimum propagation delay such that a turn-off period of less than 1 microsecond is achieved for overvoltage transients detected in the power supply path. In a possible embodiment, the sensitivity of the overvoltage detection circuit to transient or permanent overvoltages can be adjusted by a configurable threshold value.

[0013] In a possible embodiment of the protection device according to the first aspect of the present application, the control unit is connected with a user interface to receive a switching command.

[0014] The control unit of the protection device with the microcontroller can turn on or turn off at least one semiconductor power switch in the power supply path by controlling the integrated drive circuit of the protection device in response to the received switching command.

[0015] In an alternative embodiment of the protection device according to the first aspect of the present application, the control unit of the protection device is connected with a system-level controller of an automation system to receive a switching command. In this embodiment, the turning off of at least one semiconductor power switch within the power supply path is performed under the control of the control unit CU in response to a switching command CMD received from the system-level controller. In a possible embodiment, the control unit CU can receive the switching command CMD from the system-level controller through a control interface.

[0016] In another possible implementation of the protection device according to the first aspect of the present application, the protection device comprises three parallel power supply paths, each connecting an input terminal with an associated output terminal. In one possible implementation, the at least one semiconductor power switch arranged in each of the three power supply paths comprises an IGBT or a power MOSFET having a blocking voltage exceeding a normal operating voltage of a supply voltage applied to the input terminal of the power supply path of the protection device.

[0017] In another possible implementation of the protection device according to the first aspect of the present application, the control gate of the at least one semiconductor power switch is directly connected with a driver output of the drive circuit.

[0018] In another possible implementation of the protection device according to the first aspect of the present application, the protection device comprising a plurality of power supply paths comprises a corresponding number of associated overvoltage detection circuits ODC, wherein each associated overvoltage detection circuit can be connected with an input terminal and / or an output terminal of a respective power supply path.

[0019] In another possible implementation of the protection device according to the first aspect of the present application, each overvoltage detection circuit ODC connected with an input terminal or an output terminal of an associated power supply path comprises a rectifier, in particular a bridge rectifier, adapted to rectify a voltage at the respective terminal of the associated power supply path, and an analog-to-digital converter ADC adapted to convert a low-pass filtered signal into a digital signal applied to a digital comparator implemented in a microprocessor of a control unit CU of the protection device and adapted to compare the low-pass filtered signal output by the analog-to-digital converter ADC with a first adjustable digital threshold value to detect a low-frequency drift of the voltage at the respective terminal of the associated power supply path and further adapted to generate a high logic signal upon detection of a low-frequency drift.

[0020] In another possible implementation of the protection device according to the first aspect of the present application, each overvoltage detection circuit ODC further comprises a fast analog comparator, in particular a Schmitt trigger circuit, adapted to compare a rectified voltage output by the rectifier with a threshold setpoint to detect an overvoltage transient of the voltage of the respective terminal of the associated power supply path and further adapted to generate a logic enable signal to enable the drive circuit to turn off the at least one semiconductor power switch arranged in the associated power supply path upon detection of an overvoltage transient by the analog comparator of the overvoltage detection circuit ODC.

[0021] In another possible implementation of the protection device according to the first aspect of the present application, the logic signal generated by the digital comparator implemented in the microprocessor of the control unit CU and the logic enable signal generated by the analog comparator of the overvoltage detection circuit ODC are logically combined by an AND gate of the overvoltage detection circuit ODC to provide a logic voltage status signal, which is indicative of the detected instantaneous voltage status of the respective terminal of the associated power supply path, wherein the logic voltage status signal is applied to the driver input of the low voltage side of the driver circuit.

[0022] In another possible implementation of the protection device according to the first aspect of the present application, an analog high pass filter HPF is provided between the rectifier and the analog comparator, which is adapted to perform a high pass filtering of the rectified voltage output by the rectifier.

[0023] In yet another possible implementation of the protection device according to the first aspect of the present application, an analog low pass filter LPF is provided between the rectifier and the analog-to-digital converter ADC, which is adapted to perform a low pass filtering of the rectified voltage output by the rectifier.

[0024] In another possible implementation of the protection device according to the first aspect of the present application, the rectifier of the overvoltage detection circuit ODC is connected to the associated power supply path through a potential separation circuit.

[0025] In another possible implementation of the protection device according to the first aspect of the present application, the driver circuit is adapted to provide a monitoring signal to the microprocessor of the control unit CU, which is adapted to inform the microprocessor about the current operating state of the driver circuit and / or the current switching state of at least one power switch within the associated power supply path.

[0026] In another possible implementation of the protection device according to the first aspect of the present application, the threshold setpoint of the analog comparator of the overvoltage detection circuit ODC is set by the microprocessor of the control unit via a digital-to-analog converter DAC, wherein the threshold setpoint comprises a fixed threshold in the first operating mode of the protection device and a mobile threshold in the second operating mode of the protection device.

[0027] In another possible implementation of the protection device according to the first aspect of the present application, the protection device further comprises a load current sensor assembly connected in series with the at least one semiconductor power switch in the power supply path, wherein the load current sensor assembly is adapted to continuously measure a load current I L wherein the measured load current I LThe microprocessor of the control unit (CU) is notified by the load current sensor assembly to determine the instantaneous load state of the electrical load connected to the output terminal of the corresponding power supply path.

[0028] In another possible embodiment of the protection device according to the first aspect of the invention, the protection device further includes a current rise rate sensor assembly, particularly a coil, connected in series with the at least one semiconductor power switch and the load current sensor assembly, the current rise rate sensor assembly being adapted to generate a current rise rate sensor assembly that is related to the load current I. L The voltage drop corresponding to the current rise rate, and the load current I L The current flows from the input terminal along the power supply path through the current rise rate sensor assembly and at least one semiconductor power switch and load current sensor assembly to the corresponding output terminal of the power supply path.

[0029] The drive circuit of the protection device is adapted to detect an overcurrent based on the voltage drop generated by the current rise rate sensor assembly and the voltage drop along at least one semiconductor power switch, and automatically turn off the at least one semiconductor power switch within a turn-off period of less than 1 millisecond when an overcurrent is detected, so as to provide protection against overcurrent. The voltage drop generated by the current rise rate sensor assembly and the voltage drop along at least one semiconductor power switch are applied directly as a sum voltage to the driver input of the high-voltage side of the drive circuit, wherein the turn-off period of less than 1 millisecond is defined by a signal propagation delay along a control path, which includes a connection circuit connecting the current rise rate sensor assembly to the driver input of the high-voltage side of the drive circuit and an internal circuit connection within the high-voltage side of the drive circuit.

[0030] In another possible embodiment of the protection device according to the first aspect of the invention, the protection device comprises:

[0031] The first overvoltage detection circuit ODC1, which is connected to the input terminal of the associated power supply path and is adapted to determine the instantaneous voltage state at the input terminal, further includes:

[0032] The second overvoltage detection circuit ODC2 is connected to the output terminal of the associated power supply path and is adapted to determine the instantaneous voltage state at the output terminal.

[0033] In another possible embodiment of the protection device according to the first aspect of the invention, the instantaneous voltage state at the input terminal determined by the first overvoltage detection circuit ODC1 and the instantaneous voltage state at the output terminal determined by the second overvoltage detection circuit ODC2 are processed to determine the instantaneous overall voltage state at the two terminals of the associated power supply path, which is logically combined by logic gates to trigger the drive circuit of the protection device to automatically shut off at least one semiconductor power switch of the associated power supply path when an overall overvoltage state at the two terminals of the associated power supply path is detected.

[0034] In another possible embodiment of the protection device according to the first aspect of the invention, a current rise rate sensor assembly, at least one semiconductor power switch, and a load current sensor assembly are connected in series along a power supply path to form a secondary current path disposed between the input terminal and the output terminal of the protection device, wherein a primary current path including a controllable mechanical switch is disposed between the input terminal and the output terminal, the primary current path being connected in parallel with the secondary current path.

[0035] According to another aspect, the present invention also provides a method for providing protection against overvoltage to an electrical load having the features of claim 19.

[0036] According to a second aspect, the present invention provides a method for providing protection against overvoltage to an electrical load.

[0037] The method includes the following steps:

[0038] Detecting overvoltage at a power supply path including at least one semiconductor power switch, wherein the power supply path supplies load current to a connected electrical load;

[0039] A control signal is applied along a control path to the driver input of the drive circuit to trigger the shutdown of at least one semiconductor power switch of the power supply path during a short shutdown period, the shutdown period being defined by the propagation delay of the control signal along the control path and the propagation delay along the internal circuitry of the drive circuit. Attached Figure Description

[0040] In the following description, different aspects of possible embodiments of the invention will be described in more detail with reference to the accompanying drawings.

[0041] Figure 1 A block diagram illustrating a possible exemplary embodiment of a protection device according to a first aspect of the present invention is shown;

[0042] Figure 2 Another block diagram illustrating another possible exemplary embodiment of the protection device according to the first aspect of the present invention is shown;

[0043] Figure 3 Another block diagram illustrating a possible exemplary embodiment of a protection device according to the first aspect of the application is shown;

[0044] Figure 4 A circuit diagram illustrating a possible exemplary embodiment of a protection device according to the first aspect of the application is shown;

[0045] Figure 5 Another block diagram illustrating a possible exemplary embodiment of a protection device according to the first aspect of the application is shown;

[0046] Figures 6A-6D A possible implementation of a power supply path within a protection device according to the first aspect of the application is shown;

[0047] Figure 7 A flow chart illustrating a possible exemplary embodiment of a method for providing protection for an electrical load against overvoltages according to another aspect of the application is shown;

[0048] Figure 8 A circuit diagram of an internal circuit illustrating a possible implementation of a drive circuit of a protection device according to the application is shown;

[0049] Figure 9 A connection circuit of the high voltage side of the drive circuit in an embodiment of Figure 2 is shown in more detail;

[0050] Figures 10A-10B , Figures 11A-11B A signal diagram illustrating the operation of a protection device is shown. DETAILED DESCRIPTION

[0051] As can be seen from the block diagram of Figure 1 , a protection device 1 is provided for protecting an electrical load 9 connected to an output terminal 3 of the protection device 1. The protection device 1 comprises at least one input terminal 2 adapted to receive a supply voltage U IN . This supply voltage can comprise an AC supply voltage U AC from a supply network PSN. As shown in Figure 1 , the protection device 1 further comprises at least one output terminal 3. The input terminal 2 and the output terminal 3 are connected to each other by a power supply path 10 as shown in Figure 1 , which power supply path 10 comprises at least one semiconductor power switch 5. As also shown in Figure 2 , the at least one semiconductor power switch 5 can be connected in series with further components. The load 9 receives a load current I L from the output terminal 3 of the power supply path 10. The supply voltage U INIn possible implementations, a DC power supply voltage may also be included.

[0052] The protection device 1 also includes a control unit 8, which includes a processor 8A. The control unit 8 is adapted to control the drive circuit 6 of the protection device 1 to turn on or off at least one semiconductor power switch 5 disposed within the power supply path 10 in response to a received switch command CMD. In one possible implementation, the protection device 1 may receive the switch command CMD from an entity 11, which may include a user interface or a remote system-level controller. In response to the received command CMD, the microprocessor 8A of the control unit 8 can trigger the automatic on or off of at least one semiconductor power switch 5 within the power supply path 10 via the associated drive circuit 6.

[0053] like Figure 1 As shown, the protection device 1 according to the first aspect of the invention includes, in the illustrated embodiment, at least one overvoltage detection circuit (ODC) 12 connected to an associated power supply path 10. The overvoltage detection circuit 12 is adapted to detect an overvoltage condition at the associated power supply path 10 and can directly control the drive circuit 6 via a control line 13, which is connected to the driver input IN of the low-voltage side 6A of the drive circuit 6 via an AND gate 14. The overvoltage detection circuit 12 can provide an enable control signal applied to the input of the AND gate 14 via the control line 13. This also... Figure 3 The diagram is shown in more detail below. The overvoltage detection circuit 12 can directly control the drive circuit 6 via control line 13, so that when the overvoltage detection circuit 12 detects an overvoltage condition, the drive circuit 6 triggers the semiconductor power switch 5 to turn off, thereby providing protection for the load 9 from overvoltage. Figure 1 In the illustrated embodiment, the overvoltage detection circuit 12 is connected to the power supply path 10 at node 15 to detect the overvoltage state on the input side of the power supply path 10. In an alternative embodiment, the overvoltage detector circuit 12 may also be connected to the output side of the power supply path 10, i.e., to the node connected to the output terminal 3 of the protection device 1, to detect the overvoltage state on the output side of the protection device 1. Figure 1 As shown, Figure 1 The overvoltage detection circuit 12 shown is also connected to an analog-to-digital converter (ADC) 17 via signal line 16, which is connected to the input of the control unit 8 at its output side. The first output of the overvoltage detection circuit (ODC) 12, connected to an AND gate 14 via signal line 13, indicates the high-frequency transient TR (also as...) detected in the signal along the power supply path 10. Figure 10A (As shown). Another output of the overvoltage detection circuit 12 provides information about the slow voltage drift within the signal applied to the output terminal 3 of the protection device 1 via the power supply path 10. Figure 10BThe overvoltage detection circuit 12 is connected to the supply path 10 and is adapted to detect an overvoltage at the supply path 10 and to trigger the shutdown of at least one semiconductor power switch 5 provided within the supply path 10 by directly controlling the drive circuit 6 via the control line 20 between the AND gate 14 and the driver input IN of the low voltage side 6A of the drive circuit 6. Figure 1 As shown, the overvoltage detection circuit 12 and the AND gate 14 form together with the drive circuit 6 and the analog-digital converter 17 and the control unit 8 a control path 18 associated with the supply path 10.

[0054] The overvoltage detection circuit 12 associated with the supply path 10 is adapted to detect an overvoltage at the respective supply path 10 and to trigger the shutdown of at least one semiconductor power switch 5 provided within the associated supply path 10 by directly controlling the drive circuit 6 via the control line 20 between the AND gate 14 and the driver input IN of the low voltage side 6A of the drive circuit 6 when the overvoltage detection circuit 12 detects an overvoltage state to provide protection for the load 9 against overvoltage.

[0055] In a possible embodiment, the at least one semiconductor power switch 5 provided in the supply path 10 can comprise a power MOSFET, in particular an N-MOSFET. In an alternative embodiment, the semiconductor power switch 5 can also comprise an IGBT. The at least one semiconductor power switch 5 has a blocking voltage exceeding the normal operating voltage of the received AC supply voltage U AC applied to the input terminal 2 of the protection device 1. The control gate 21 of the at least one semiconductor power switch 5 is directly connected to the driver output OUT of the drive circuit 6 of the high voltage side 6B of the drive circuit 6. In a preferred embodiment, the drive circuit 6 is adapted to shut down the at least one semiconductor power switch 5 within a shutdown period of less than 1 millisecond by the control line 19, which shutdown period is defined by the signal propagation delay along the first control line 13, the output of the AND gate 14 and the control line 20 between the driver input IN and the driver output OUT of the drive circuit 6 and the propagation delay along the internal circuit of the drive circuit 6. In a possible embodiment, the signal propagation delay within the internal circuit of the drive circuit 6 between the driver input IN and the driver output OUT is less than 200 nanoseconds. Depending on the implementation of the overvoltage detection circuit 12, a very short shutdown period can be achieved. In a possible embodiment, the shutdown period can be as low as 1 microsecond. In any case, a short shutdown period of less than 1 millisecond is provided, which shutdown period is defined by the signal propagation delay along the first control line 13, the output of the AND gate 14 and the control line 20 between the driver input IN and the driver output OUT of the drive circuit 6 and the propagation delay along the internal circuit of the drive circuit 6. Figure 1The propagation delay along the control line starting from the node 15 and ending at the control gate 21 of the power switch 5 is defined as illustrated. The signal propagation delay between the node 15 and the control gate 21 of at least one semiconductor power switch 5 within the supply path 10 thus defines the turn-off period for turning off the semiconductor power switch 5 in response to an occurring overvoltage. Since the propagation delay along the drive circuit 6 is very low and comprises less than 200 nanoseconds, a very short turn-off period of 1 microsecond can be achieved in possible embodiments. Even when using a relatively slow circuit in the overvoltage detection circuit 12, a very low turn-off period of less than 1 millisecond can still be achieved using the drive circuit 6. In possible embodiments, a drive circuit 1ED020 / 12-B2 manufactured by Infineo Technologies can be used. This drive circuit comprises two separate circuit halves galvanically separated from each other by transformers T1, T2, as also illustrated in Figure 4 The drive circuit 6 comprises a low voltage side 6A and a high voltage side 6B. A driver input IN provided at the low voltage side receives signals from the overvoltage detection circuit 12 and from the control unit 8 via the AND gate 14. A driver output OUT of the drive circuit 6 provided at the high voltage side 6B directly connects the drive circuit 6 to the control input 21 of the controllable power switch 5.

[0056] In Figure 1 In the illustrated embodiment, a logic signal generated by a digital comparator COMP1 implemented in the microprocessor 8A of the control unit 8 and a logic enable signal generated by an analog comparator COMP2 of the overvoltage detection circuit 12 are logically combined by the AND gate 14 to provide a logic voltage status signal indicating the instantaneous voltage status detected at the supply path 10. The logic voltage status signal is applied to the driver input IN of the low voltage side 6A of the drive circuit 6 via the control line 20. In possible embodiments, the drive circuit 6 is further adapted to provide a monitoring signal to the microprocessor 8A of the control unit 8, which monitoring signal is adapted to inform the microprocessor 8A about the current operating status of the drive circuit 6 itself and / or about the current switching status of at least one power switch 5 provided within the supply path 10. In Figure 1 In the illustrated embodiment, the drive circuit 6 provides the monitoring signal to the microprocessor 8A of the control unit 8 via a signal line 22.

[0057] Figure 2 A block diagram illustrating another possible embodiment of the protection device 1 according to the present application is shown. In Figure 2 In the illustrated embodiment, the supply path 10 between the input terminal 2 and the output terminal 3 comprises additional components, in particular a current rise speed sensor component 4 and a load current sensor component 7. The current rise speed sensor component 4 can be constituted by a coil. As Figure 2As shown, the load current sensor assembly 7 is connected in series with at least one power switch 5 in the power supply path 10. The load current sensor assembly 7 is adapted to continuously measure the load current I flowing through at least one semiconductor power switch 5 in the power supply path 10 of the electrical load 9 connected to the output terminal 3. L The load current sensor assembly 7 is transmitted via... Figure 2 The signal line 23 shown will measure the load current I. L The microprocessor 8A of the control unit 8 is notified. The microprocessor 8A of the control unit 8 is adapted to receive the load current I via signal line 23. L The instantaneous load state of the electrical load 9 connected to the output terminal 3 of the power supply path 10 is determined. The current measurement unit 7 can be implemented by a Hall sensor. In another alternative embodiment, the load current sensor assembly 7 may also include a GMR sensor. In yet another alternative embodiment, the load current sensor assembly 7 may also be formed by a transformer connected to the input terminal of the control unit 8 via an analog-to-digital converter. Therefore, the load current sensor assembly 7 of the protection device 1 may include components adapted to continuously measure the load current I flowing to the output terminal 3 of the power supply path 10. L Hall effect sensors, GMR sensors, shunt resistors or transformers, load current I L Notified to control unit 8. Continuously measured load current I L A load current profile can be provided, and in a possible implementation, the load current profile can be stored in the data memory of the control unit 8.

[0058] In a possible implementation, power supply path 10 may include additional components, such as a relay, that can be directly controlled by the microprocessor 8A of control unit 8. Such a mechanical switch in power supply path 10 can provide additional safety in the event of a failure to turn off the semiconductor power switch 5. In one possible implementation, if the microprocessor 8A of control unit 8 has determined an overload condition of electrical load 9, the electromechanical relay may be connected in series with at least one semiconductor power switch 5 to interrupt current flow. In one possible implementation, the load current I measured by load current sensor assembly 7... L The measured values ​​can be converted into digital values ​​stored in the data memory of the control unit 8 using an analog-to-digital converter.

[0059] exist Figure 2 As can be seen, the current rise rate sensor assembly 4, which can be composed of coils, is connected in series with at least one semiconductor power switch 5 and a load current sensor assembly 7 within the power supply path 10. The current rise rate sensor assembly 4 is adapted to generate a load current I flowing through the power supply path 10. L The voltage drop ΔU4 corresponds to the rate of current rise. Furthermore, as... Figure 2As shown, there is a voltage drop ΔU5 along the semiconductor power switch 5, for example, along the drain-source voltage U of the MOSFET 5. DS The generated voltage drop ΔU4 and the voltage drop ΔU5 along the semiconductor power switch 5 are taken as the sum voltage U. ∑ Apply directly to Figure 2 The high-voltage side 6B of the drive circuit 6 shown is the driver input terminal DESAT. The applied total voltage U... ∑ Upon detection of an overcurrent flowing through the power supply path 10, at least one semiconductor power switch 5 can be automatically turned off within a shutdown period of less than 1 millisecond, thus providing additional protection against overcurrent. Therefore, it provides... Figure 2 The protection device 1 shown in the embodiment provides protection against overvoltage and overcurrent. The less than 1 millisecond shutdown period providing overcurrent protection is defined by a signal propagation delay along another control loop, which includes internal circuitry connecting the current rise rate sensor assembly 4 along signal lines 24A, 24B to the driver input terminal DESAT of the high-voltage side 6B of the drive circuit 6, and internal circuitry of the high-voltage side 6B of the drive circuit 6. The signal propagation delay caused by the internal circuitry of the high-voltage side 6B is even lower than the propagation delay from the driver input terminal IN of the low-voltage side 6A to the driver output terminal OUT of the high-voltage side 6B. Therefore, the signal propagation delay caused by the internal circuitry of the high-voltage side 6B between the DESAT input terminal and the driver output terminal OUT is less than 200 nanoseconds. Total voltage U ∑ Corresponding to Figure 3 The voltage drop between nodes 25A and 25B in the power supply path 10 shown is such that nodes 25A and 25B are connected to the input terminal of the high-voltage side 6B of the drive circuit 6 via signal lines 24A and 24B.

[0060] Figure 3 Another block diagram illustrating a possible embodiment of the protective device 1 according to the first aspect of the present invention is shown. Figure 3 A possible exemplary implementation of the overvoltage detection circuit (ODC) 12 within the protection device 1 is shown in more detail. The overvoltage detection circuit 12 is associated with the power supply path 10 and is adapted to detect overvoltages within the power supply path 10. Figure 4In the illustrated embodiment, the overvoltage detection circuit 12 is connected to the power supply path 10 at node 15 on its input side. In the illustrated embodiment, the overvoltage detection circuit 12 includes a potential separation circuit 26 adapted to provide potential separation between the power supply path 10 and other circuitry of the overvoltage detection circuit 12. The potential separation circuit 26 provides potential separation between the high-voltage side (i.e., the power supply path 10) and the low-voltage side of the circuitry including the overvoltage detection circuit 12. On the high-voltage side, depending on the application, there may be a high voltage exceeding 400 volts (up to 1500 volts). On the low-voltage side, the typical supply voltage of the control circuitry varies between 5 and 24 volts DC. The overvoltage detection circuit 12 includes a rectifier 27 adapted to rectify the voltage received through the potential separation circuit 26. The rectifier 27 may include, for example, a bridge rectifier, or... Figure 3 As shown. In Figure 3 In the illustrated embodiment, the overvoltage detection circuit 12 includes an analog high-pass filter (HPF) 28 adapted to perform high-pass filtering on the rectified voltage output from the rectifier 27. For example... Figure 3 As shown, the high-pass filter 28 is connected to the output terminal of the rectifier 27 via signal line 29. Figure 10B In the illustrated embodiment, the overvoltage detection circuit 12 may further include a low-pass filter (LPF) 30 connected to the output of the rectifier 27 via signal line 31. The low-pass filter 30 is adapted to perform low-pass filtering on the rectified voltage output by the rectifier 27. The output of the low-pass filter 30 is connected to an analog-to-digital converter (ADC) 17 via signal line 32, which converts the low-pass filtered signal into digital samples. These digital samples are applied via signal line 33 to a digital comparator 34 implemented in the microprocessor 8A of the control unit 8. The ADC 17 is adapted to convert the low-pass filtered signal received from the low-pass filter 30 into a digital signal or sample, which is applied to the digital comparator 34 implemented in the microprocessor 8A of the control unit 8. The digital comparator 34 implemented in the microprocessor 8A is adapted to compare the low-pass filtered digital signal output by the ADC 17 with a first adjustable digital threshold TH1 to detect overvoltage. Figure 3 The voltage at power supply path 10 shown exhibits a low-frequency drift. Digital comparator COMP1 34 is adapted to generate a high logic signal upon detection of the low-frequency drift, wherein the high logic signal is provided via signal line 35. Figure 3 The input terminal of AND gate 14 is shown.

[0061] Figure 4 The overvoltage detection circuit 12 shown also includes a fast analog comparator COMP2 36 connected to the output of the high-pass filter 28 via signal line 37. In one possible implementation, as... Figure 10AIn the embodiment shown, the analog comparator COMP2 36 can be formed by a Schmitt trigger circuit. The analog comparator 36 is adapted to compare the rectified voltage output by the rectifier 27, which is high-pass filtered by a high-pass filter (HPF) 28, with a threshold setpoint TH2 to detect an overvoltage transient TR of the voltage at the supply path 10, as also shown in Figure 3 The analog comparator 36 is adapted to generate a logic enable signal applied via the control line 13 to an input terminal of the AND gate 14, as shown. The generated logic enable signal is provided for enabling the drive circuit 6 to turn off at least one semiconductor power switch 5 arranged within the associated supply path 10 when the analog comparator 36 detects the overvoltage transient TR. In the embodiment shown, the threshold setpoint TH2 of the analog comparator COMP2 36 of the overvoltage detection circuit 12 can be set by the microprocessor 8A of the control unit 8 via a digital-to-analog converter DAC 38. The threshold setpoint TH2 can comprise a fixed threshold in the first operating mode of the protection device 1. Furthermore, the threshold setpoint TH2 can also comprise a mobile threshold in the second operating mode of the protection device 1. Figure 3 Figure 3

[0062] Figure 4 The overvoltage detection circuit 12 shown in the embodiment of Fig. 1 comprises an analog high-pass filter (HPF) 28 and an analog low-pass filter (LPF) 30. The provision of the analog high-pass filter 28 and the analog low-pass filter 30 is optional. Thus, in alternative embodiments, the overvoltage detection circuit 12 can dispense with the high-pass filter (HPF) 28 and the low-pass filter (LPF) 30. In possible implementations, the analog-to-digital converter (ADC) 17 and the digital-to-analog converter (DAC) 38 can also be integrated in the control unit 8. The sampling rate of the ADC 17 and the conversion rate of the DAC 38 can be controlled by the microprocessor 8A.

[0063] Figure 4 A circuit diagram for illustrating a possible exemplary embodiment of the protection device 1 according to the first aspect of the present application is shown. Figure 8 and Figure 8 The drive circuit 6 is shown in more detail. As shown in Figure 4 The drive circuit 6 comprises a low-voltage side 6A and a high-voltage side 6B separated by transformers T1, T2.

[0064] ​​The overvoltage detection circuit 12 is connected at nodes 15A, 15B with the AC line and the neutral line N, which are connected with the supply path 10. The overvoltage detection circuit (ODC) 12 comprises in the shown embodiment at its input side a potential separation circuit 26, which is implemented by two resistors 26A, 26B with a high resistance of more than 1 MOhm. This high resistance provides a potential separation of the input of the overvoltage detection circuit 12 from the potential of the high voltage supply path. The high resistance of the resistors 26A, 26B provides a high impedance coupling to the input terminal 2, which can be connected with an AC grid or supply network PSN, to avoid any overcurrent flow into the circuit of the overvoltage detection circuit 12. In an alternative embodiment, the input terminal 2 can be connected with a DC supply source. In an alternative implementation, the potential separation circuit 26 can be implemented by other means, for example by an inductive coupling. The rectifier 27 is implemented in the shown embodiment as a bridge rectifier comprising four diodes D. The bridge rectifier 27 is adapted to rectify the voltage received from the potential separation circuit 26 to provide a rectified output voltage. The analog comparator COMP2 36 is implemented in the shown embodiment by a Schmitt trigger circuit. In the shown implementation, the inverting input (-) of the operational amplifier of the Schmitt trigger comparator 36 is connected with the bridge rectifier circuit 27 through a Z-diode 38. The Z-diode 38 provides a stronger robustness against false triggering of the analog comparator COMP2 36 compared to a pure resistive coupling. The Schmitt trigger comparator 36 comprises a hysteresis.

[0065] The output voltage provided by the bridge rectifier 27 can be provided through a signal conditioning circuit 39 consisting of two resistors 39A, 39B through signal lines 31A, 31B to the input of the analog to digital converter (ADC) 17. The logic signal transported through the signal lines 31A, 31B provides information about the signal amplitude at the AC line connected with the input terminal 2 of the protection device 1. The analog to digital converter 17 converts the received signal to digital samples, which are applied through a signal line 33 to a digital comparator 34 implemented in the microprocessor 8A of the control unit 8. The digital comparator 34 is adapted to compare the converted digital samples with a first adjustable digital threshold value TH1 to detect a low frequency drift of the voltage at the AC line connected with the input terminal 2 of the protection device 1. If a low frequency drift is detected, the digital comparator 34 provides a high voltage signal and applies a high logic signal through a signal line 35 to an input of the AND gate 14. Figure 4 An advantage of the shown implementation is that the comparator 34 can be implemented in the microcontroller 8A of the control unit 8 and can be directly controlled by a control program executed by the microprocessor 8A. Thus, the threshold value can be set in this control path by a software control program.

[0066] Furthermore, in the shown implementation, the threshold setpoint of the analog comparator (e.g. Schmitt trigger 36) is set by the microprocessor 8A of the control unit 8 through Figure 4 The shown digital-to-analog converter (DAC) 38 is set. In a first operating mode of the protection device 1, a fixed threshold is set. In this operating mode, the analog comparator COMP2 36 is triggered only according to the absolute amplitude (superposition of 50 Hz and overvoltage peaks). In a second operating mode of the protection device 1, a mobile threshold is set. In this second operating mode, the signal-to-noise ratio SNR can be increased during normal operation of the protection device 1. The comparator setpoint can be decreased when the 50 Hz signal is high and can be increased when the 50 Hz signal is low.

[0067] If the AC voltage U AC Within the allowed range, the analog fast Schmitt trigger comparator COMP2 36 provides a high logic signal in the shown implementation and applies this high logic signal through the signal line 13 to the first input of the AND gate 14. In contrast, if the AC voltage U AC is too high and an overvoltage is present, the analog comparator 36 provides a low logic signal which is applied through the signal line 13 to the first input of the AND gate 14. The output signal of the analog comparator COMP2 36 (Schmitt trigger) thus provides an enable signal which enables the transmission of the logic control signal from the microprocessor 8A through the second input of the AND gate 14 to the driver input IN of the low voltage side 6A of the drive circuit 6. The control unit 8 can receive an ON or OFF command CMD from the entity 11, i.e. from the user interface or from a system level controller. If the received command CMD is an ON command, a high logic signal is provided through the control line 35 to the second input of the AND gate 14. This high logic signal can only be transmitted to the output of the AND gate 14 and can be provided through the signal line 20 to the driver input IN if the enable signal ENABLE provided by the analog comparator 36 is high. Thus, if a high frequency transient TR is present on the AC line of the supply path 10, the ENABLE signal is low and blocks the AND gate 14 so that the non-inverted input IN+ of the low voltage side 6A of the drive circuit 6 does not receive a high logic signal even if the control unit 8 outputs a high logic ON command through the line 35. The microprocessor 8A provides a user-controllable ON, OFF signal through the signal line 35 to the second input of the AND gate 14. If a high logic signal is applied to both signal inputs of the AND gate 14, a high level control signal is applied to the driver input IN of the low voltage side 6A of the drive circuit 6. The drive circuit 6 can be provided by a drive circuit chip which has pins at the low voltage side 6A and pins at the high voltage side 6B. The signal transmission across the galvanic isolation is realized by the transformers T1, T2 which provide an inductive coupling between the low voltage side 6A and the high voltage side 6B of the drive circuit 6.Figure 4 In the illustrated embodiment, the signal line 20 connects the output of the AND gate 14 with the non-inverted driver input IN+ of the drive circuit 6. In a possible implementation, the drive circuit 6 further comprises an inverted driver input.

[0068] Figure 8 The illustrated drive circuit 6 can comprise Figure 4 The illustrated drive circuit 6 is an IED020112-B2 drive circuit produced by Infineon Technologies. The drive circuit 6 consists of two galvanically separated parts. The low voltage side 6A is connected with the overvoltage detection circuit and the microprocessor 8A of the control unit 8. The output side 6B of the drive circuit 6 is connected with the high voltage supply path 10. The driver output OUT of the high voltage side 6B can use an integrated MOSFET to provide a rail-to-rail output signal. As Figure 9 illustrated, the driver output OUT is directly connected with the control gate 21A, 21B of the semiconductor power switch 5A, 5B via the signal lines 15A, 15B. The semiconductor power switch 5A, 5B is in the illustrated implementation a power N-MOSFET. In the illustrated embodiment, the power MOSFET 5A, 5B is connected in series with the associated current rise speed sensor assembly 4A, 4B which is implemented as a coil. These coils 4A, 4B are provided to generate a sensor signal to provide overcurrent protection. The semiconductor power switch 5A, 5B as well as the current rise speed sensor assembly 4A, 4B are arranged within the supply path 10 connecting the input terminal 2 and the output terminal 3. The coils 4A, 4B can be connected with the DESAT input pin of the high voltage side 6B of the drive circuit 6 via a rectifier stage 40 (shown in more detail in Figure 2 ). The voltage drop AU5 along the semiconductor power switch 5A, 5B corresponds to the drain-source voltage U DS . The voltage drop AU5 along the semiconductor power switch 5 and the voltage drop AU4 along the current rise speed sensor assembly 4, i.e. the coil 4, are applied as a sum voltage U ∑ to the DESAT driver input of the drive circuit 6. The current rise speed sensor assembly 4 not only measures the current rise speed dl / dt, but can also provide additional protection for the semiconductor power switch 5 by limiting the voltage drop, i.e. the drain-source voltage U DS at the power MOSFET 5. The sum voltage U ∑ comprises the voltage drop AU4 of the coil 4 which is linearly related to the current rise speed (dl / dt), plus the voltage drop AU5 along the semiconductor power switch 5 which has a non-linear drain-source voltage U DS . The drive circuit 6 is adapted to base the switching of the semiconductor power switch 5 on the received sum voltage U ∑A short circuit occurring within the power supply path 10 is determined. In a possible implementation, the drive circuit 6 can turn off the power supply switch 5 within less than 1 microsecond upon detection of an overcurrent. The inductance L of the current rise speed sensor assembly 4 can be adapted individually to the physical limitations of the semiconductor power supply switch 5 used. The coil 4 is very robust against environmental influences and does not involve any electronic circuitry for generating the sensor voltage AU4. Thus, the hardware sensor assembly 4 has a very low probability of failure during operation of the protection device 1. The use of a hardware sensor assembly 4, in particular of a coil, in comparison to a conventional electronic circuit such as a differentiator makes the protection device 1 robust and increases its working life. It is worth noting that the turn-off operation in case of an overcurrent is performed by the analog drive circuit 6 without involving the comparatively slow control unit 8. The turn-off operation is performed automatically in response to a detected overvoltage. The detection is performed by the overvoltage detection circuit 12. The turn-off operation caused by a detected overvoltage is performed by the drive circuit 6 without involving the slow control unit 8, so that a very short turn-off period in the range of less than 1 millisecond or even a few microseconds can be achieved. Furthermore, in case of an overcurrent detected by the voltage drop along the coil 4 and the power supply switch 5, a very fast turn-off operation is triggered as well without involving the slow control unit 8. Thus, the turn-off of at least one power supply switch 5 in the power supply path 10 can be achieved as well within a short turn-off period of less than 1 millisecond. The current rise speed sensor assembly 4 is sensitive and generates the sensor voltage AU4 even before the current flowing to the load 9 reaches a high current level that can damage components of the connected load 9. The fast turn-off operation provided by the hardware drive circuit 6 in response to a detected overvoltage and / or in response to a detected overcurrent guarantees that only a small portion of the electrical energy is provided to the connected load 9 in case of an overvoltage and / or in case of an overcurrent occurring.

[0069] The applied AC supply voltage U applied to the terminals 2 AC A frequency of e.g. 50 to 60 Hz can be included in a possible implementation. The current rise speed sensor assembly 4 can comprise a coil which in a possible implementation comprises an inductance L of about 1 μH (AU4 ~ L dI / dt) micro henries. For the protection device 1 according to the present application, the drive circuit 6 indeed operates independently from the control unit 8 to turn off the associated semiconductor power supply switch 5A, 5B within a short reaction time upon detection of an overvoltage or an overcurrent.

[0070] In a possible implementation, the protection device 1 comprises a load current sensor assembly 7. Figure 1 In the illustrated implementation of the load current sensor assembly 7, the protection device 1 provides protection against overload conditions as well. Thus, the protection device 1 provides different protection mechanisms while using a single drive circuit 6.

[0071] For overload protection, the logic signal applied to the driver input IN+ is passed through the gate of the low voltage side 6A and inductively coupled to the high voltage side 6B of the drive circuit 6 and transmitted along the gate to the driver output OUT of the drive circuit 6. In contrast, for overcurrent protection, the sum voltage U ∑ the DESAT input pin of the high voltage side 6B directly and transmitted along the gate to the driver output OUT by the comparator K3. In a possible implementation, the threshold voltage of the comparator K3 can be adjustable. Thus, the sensitivity of the drive circuit 6 to the sum voltage U ∑ overcurrent can be adjusted. For the protection device 1 comprising the overvoltage detection circuit 12, the voltage at the supply path 10 is monitored and, in case of an overvoltage event, the semiconductor power switch 5 is automatically turned off, i.e. opened, as long as the overvoltage is present. As long as the semiconductor power switch 5 is closed, the high impedance between the source and the load 9 keeps the overvoltage isolated from the connected load 9. To ensure proper operation, the blocking voltage of at least one semiconductor power switch 5 is higher than any expected overvoltage at the supply grid side.

[0072] The protection device 1 according to the present application has the advantage that it can monitor each phase of a multi-phase supply system or supply network PSN connected to the input terminals 2 individually. Thus, if an overvoltage and / or overcurrent is detected on one of the supply lines of the supply network PSN, the turn-off of the semiconductor power switch 5 is triggered to protect the load 9 connected to the output terminals 3 of the protection device 1. The detection response time provided by the protection device 1 is also sufficient to handle high frequency overvoltage transients TR. The turn-off during a transient TR provided by the protection device 1 according to the present application is in the range of a few microseconds in a possible implementation. In any case, the reaction time is less than 1 millisecond. This is achievable because the drive circuit 6 comprises a very low propagation delay of less than 200 nanoseconds. Furthermore, a high degree of flexibility is achieved by the digitally adjustable turn-off threshold of each supply path 10, which can be set in a possible implementation by a user interface connected to the microprocessor 8A of the control unit 8.

[0073] The connected load 9 can comprise different kinds of loads, in particular inductive loads such as electric motors. The load can also comprise resistive loads, for example heaters.

[0074] The protection device 1 according to the application arranged between the supply network PSN and the load 9 is fully controllable and has a fast semiconductor power switch 5 connected with the driver output OUT of the driver circuit 6. In the event of a voltage at the input terminal 2 of the supply path 10 exceeding an adjustable threshold value, the semiconductor power switch 5 is automatically switched off with a very small delay time. This delay time is defined by the signal propagation delay along the control path between the node 15 and the control gate 21 of the semiconductor power switch 5, as is also shown in Figure 5 After the at least one semiconductor power switch 5 has been switched off, it comprises a very high impedance which, if an overvoltage event is detected, suppresses any overcurrent flowing from the supply network PSN to the connected load 9. In a possible implementation, the at least one semiconductor power switch 5 can be automatically switched on again after a waiting time if the overvoltage has disappeared. With the protection device 1 according to the application, in the event of a detection of an overvoltage event, the impedance between the power supply and the load 9 is raised, thus providing additional protection for the load 9. The semiconductor power switch 5 can provide an impedance greater than 1 MΩ in the switched-off state, which protects the load 9 from overvoltage. The semiconductor power switch 5 provides a low resistance in the switched-on state, thus generating only little dissipated power.

[0075] Figure 1 A possible implementation of the protection device 1 according to the application is shown. In the implementation shown, the protection device 1 comprises three parallel supply paths 10-1, 10-2, 10-3. Each supply path 10-1, 10-2, 10-3 comprises an associated control path 18-1, 18-2, 18-3, which can be implemented as shown in the implementation of Figures 6A-6B Thus, each supply path 10-1, 10-2, 10-3 can be individually protected from overcurrent and / or overvoltage. Each supply path 10-i can comprise at least one semiconductor power switch 5. Furthermore, the supply path 10-i can comprise additional components connected in series, for example a current rise speed sensor component 4 or a load current sensor component 7. Each control path 18-1 can comprise a separate overcurrent detection circuit 12. The control unit 8 of the protection device 1 can be arranged for all three control paths 18-1, 18-2, 18-3 in a possible implementation.

[0076] Figure 6A An alternative possible implementation of the arrangement of the semiconductor power switch 5 in the supply path 10 is shown. In a preferred implementation, each supply path 10 is provided with a separate control path 18-1, 18-2, 18-3, which is connected to the control unit 8 of the protection device 1. The control unit 8 is arranged to control the semiconductor power switch 5 in each supply path 10-1, 10-2, 10-3. Figure 6BThe diagram shows a pair of N-MOSFETs controlled by a single drive circuit 6. Connecting the two power MOSFETs in series does indeed increase the blocking voltage provided in the power supply path 10 when both power MOSFETs are turned off by drive circuit 6. IGBTs can also be used instead of power MOSFETs. Alternatively, SiC MOSFETs can be used.

[0077] Figure 6B The configuration of the power MOSFET pairs connected in parallel within the power supply path 10 controlled by the common drive circuit 6 is explained. Figure 6C The implementation described herein provides the ability to increase the current of the power supply path 10 as needed based on usage conditions.

[0078] Figure 6C Another possible implementation is illustrated, in which multiple drive circuits 6-i control an overlapping pair of multiple semiconductor power switches 5 in response to a control signal output by AND gate 14 and applied to... Figure 6C The driver input terminals of the different drive circuits 6 are shown. Because... Figure 6D The numerous series-connected semiconductor power switches 5 shown can have their blocking voltage significantly increased depending on the application.

[0079] Figure 6B It shows the formation Figure 6C The embodiments shown and Figure 6D Another possible alternative implementation of the combination of the illustrated embodiments. Figure 6D In the illustrated embodiment, multiple power switches 5 are connected in series, and multiple power switches 5 are connected in parallel to be driven by corresponding drive circuits 6. Figures 6A-6D In the example shown, six semiconductor power switches 5 are connected in series, and three semiconductor power switches 5 are connected in parallel. Figure 7 The illustrated implementation simultaneously provides increased blocking voltage and higher current capability for power supply path 10. The number of series-connected and parallel-connected semiconductor power switches 5 can be adjusted according to usage, particularly according to the supply voltage U of the power supply network PSN. AC It varies with the connected load 9.

[0080] Further embodiments of the protection device 1 are possible. In one possible embodiment, the protection device 1 does not only comprise one overvoltage detection circuit (ODC) 12, but two overvoltage detection circuits 12. In this embodiment, a first overvoltage detection circuit (ODC1) 12 can be connected with the input terminal 2 of the associated power supply path 10 and can be adapted to determine the instantaneous voltage state at the input terminal 2. A second overvoltage detection circuit (ODC2) 12 can be connected with the output terminal 3 of the associated power supply path 10 and can be adapted to determine the instantaneous voltage state at the output terminal 3. Thus, the advantage of this embodiment is that it not only monitors the voltage state at the input side of the protection device 1, but also at the output side of the protection device 1. In this embodiment, the instantaneous voltage state of the input terminal 2 determined by the first overvoltage detection circuit (ODC1) 12 and the instantaneous voltage state of the output terminal 2 determined by the second overvoltage detection circuit (ODC2) 12 can be processed to determine the instantaneous overall voltage state at both terminals (i.e. input terminal 2 and output terminal 3) of the protection device 1. In a possible implementation, the instantaneous voltage state at the input terminal 2 and the instantaneous voltage state at the output terminal 3 can be logically combined by a logic gate to trigger the drive circuit 6 of the protection device 1 to automatically turn off at least one semiconductor power switch 5 of the associated power supply path 10 upon detection of an overall overvoltage state of both terminals 2, 3 of the protection device 1.

[0081] In another possible embodiment of the protection device according to the first aspect of the present application, the current rise rate sensor assembly 4 (i.e. the coil) and the at least one semiconductor power switch 5 connected in series along the power supply path 10 as well as the load current sensor assembly 7 indeed form a secondary current path within the protection device 1 arranged between the input terminal 2 and the output terminal 3. In this embodiment, the protection device 1 can comprise an additional primary current path arranged between the input terminal 2 and the output terminal 3 of the protection device 1, which has a controllable mechanical switch, e.g. a thomson switch, and is connected in parallel to the second current path (i.e. the power supply path 10) of the protection device 1. If the mechanical switch is turned off by the controller during operation, the current flowing through the primary current path is diverted to the parallel secondary current path provided by the power supply path 10, thereby suppressing the generation of an electric arc at the mechanical contacts of the mechanical switch.

[0082] Figure 1 A flow chart illustrating an exemplary embodiment of a method of providing protection from overvoltages is shown. The method comprises in the illustrated embodiment two main steps.

[0083] In a first step S1 an overvoltage at the supply path 10 is detected by an overvoltage detection circuit (ODC) 12 which provides a control signal to the driver input IN of the driver of the low voltage side 6A of the drive circuit 6 via the control signal line 13 and the signal line 20 at the AND gate 14 to automatically trigger the turn-off of the semiconductor power switch 5 in the supply path 10 in a further step S2. The turn-off of the semiconductor power switch 5 within the supply path 10 can be performed very fast within a turn-off period of less than 1 millisecond. The turn-off period is defined by the circuit of the overvoltage detection circuit 12 and the internal circuit of the drive circuit 6. The turn-off period of less than 1 millisecond is defined between the node 15 in the control loop shown in Fig. 1 and the control gate 21 of the at least one semiconductor switch 5. Since the drive circuit 6 comprises an internal propagation delay of less than 200 nanoseconds, the turn-off period can even be lower in possible implementations and can comprise only a few microseconds. This provides a very effective overvoltage protection for the connected load 9. As shown in Fig. 1 the overvoltage protection method provides an overvoltage protection especially also against high frequency transients TR. Figure 10A Figure 8

[0084] The protection device 1 according to the present application has the additional advantage that the turn-off of the semiconductor power switch 5 does not need that the received sinusoidal supply voltage must be 0 volt to perform the turn-off. The turn-off can be performed at any time independent of the current state of the received sinusoidal AC supply voltage U AC

[0085] Figure 8 A circuit diagram of a possible exemplary implementation of the drive circuit 6 used by the protection device 1 according to the first aspect of the present application is shown in more detail. Figure 8 The drive circuit 6 shown in Fig. 2 can be used to drive an IGBT or a power MOSFET. In Figure 8 It can be seen in Fig. 2 that the drive circuit 6 consists of two galvanically separated parts. The drive circuit 6 comprises a low voltage side 6A and a high voltage side 6B. The low voltage side 6A comprises a non-inverted input IN+ and an inverted input IN-. As shown in Fig. 2 the two sides 6A, 6B are galvanically separated and coupled by transformers T1, T2. The non-inverted input IN+ of the low voltage side 6A is used to receive the logic output signal from the AND gate 14. The output OUT of the high voltage side 6B is used to control the gate 21 of the semiconductor power switch 5 at the control line 19. Figure 2

[0086] The DESAT input of the high voltage side 6B is used to receive the current rise speed sensor assembly 4 and Figure 8 ​​​​The sum of voltages U along the voltage drop ΔU5 of power switch 5 is shown. ∑ The sum of the voltage U at the DESAT input terminal of the high-voltage side 6B of the drive circuit 6. ∑ Can be with Figure 9 The threshold voltage U at comparator K3 shown TH Compare them. If the sum of voltages U ∑ Exceeding the configurable threshold voltage U TH The high logic signal is then transmitted along the logic gates in the control loop within the high-voltage side 6B to the driver output OUT of the driver circuit 6. The internal propagation delay from the DESAT input to the driver output OUT within the high-voltage side 6B of the driver circuit 6 is extremely low and does not exceed 200 nanoseconds. If the total voltage U ∑ Exceeding the configurable threshold voltage U TH The high logic signal then travels along OR gate OR1, AND gate AND1, and another AND gate AND2 to the operational amplifier AMP, which drives the output stage at the driver output OUT. The propagation delay time of this internal control loop is less than 200 nanoseconds.

[0087] The logic signal applied to the non-inverting input terminal IN+ of the driver circuit 6 is applied to AND gate AND3 and coupled to AND gate AND2 on the high-voltage side 6B through transformer T1, so as to be output by the driver output terminal OUT of the high-voltage side 6B to trigger the switching of the connected semiconductor switch 5. The signal propagation delay between the driver input terminal IN+ and the driver output terminal OUT does not exceed 200 nanoseconds.

[0088] Figure 9 The circuit connecting coils 4A and 4B to the DESAT driver input of the high-voltage side 6B of the drive circuit 6 is shown in more detail. Therefore, the protection device 1 uses a single drive circuit 6 for overcurrent detection by processing the sum signal U∑ applied to the DESAT input of the output side 6B of the drive circuit 6 and the logic signal IN+ applied to the low-voltage side 6A of the drive circuit 6. The signal path from the logic input IN+ to the driver output OUT, and the signal path between the DESAT input and the driver output, both have a low propagation delay of less than 200 nanoseconds. Figure 9 The circuit connecting coils 4A and 4B to the DESAT input terminal of the high-voltage side 6B of the drive circuit 6 is shown in more detail.

[0089] Protection device 1 includes input terminal 2 to receive supply voltage U from a power supply network PSN having, for example, 400 volts or higher. ACPower supply path 10 includes semiconductor power switches 5A and 5B associated with the current rise rate sensor assembly 4, particularly the coil. The circuit is symmetrical for the positive and negative current half-waves of the AC current applied to the load 9 through power supply path 10. Each coil 4A and 4B includes... Figure 9 The associated semiconductor power switches 5A and 5B are shown. In one possible implementation, both coils 4A and 4B can include an inductance L of less than about 2.2 microhenries. Power switches 5A and 5B can be implemented using power MOSFETs. In the illustrated implementation, diodes can be connected in parallel to each coil 4A and 4B to reduce self-inductance. Power switches 5A and 5B are connected to a bridge rectifier circuit, which in the illustrated implementation includes two pairs of complementary transistors Q1 to Q4. On the output side of the bridge rectifier circuit, a capacitor C can be provided to provide a predetermined minimum delay. This delay may affect the turn-off period. In one possible implementation, the delay can be adjusted by changing the capacitance of capacitor C, thereby adjusting the turn-off period to meet the requirements of the appropriate use case, for example, in the range between 1 microsecond and 1 millisecond. Figure 9 The resistances of resistors R1 and R2 shown can be configured to be adjusted. Figure 9 The sensitivity of the circuit shown. Figure 4 As can be seen, the DESAT input terminal of the high-voltage side 6B of the drive circuit 6 is connected to the output terminal of the bridge rectifier circuit to receive the sum voltage U of the power switches 5A, 5B and the associated current rise sensor assemblies 4A, 4B. ∑ The drive circuit 6 generates the applied power. Figure 9 The control voltages of the gates 21A and 21B of the two semiconductor power switches 5A and 5B are shown. The drive circuit 6 is adapted to detect overcurrents, particularly short-circuit currents, based on voltages directly generated by sensor components 4A and 4B, and, upon detecting a short-circuit current flowing along the current path between input terminal 2 and output terminal 3 along the power supply path 10, to turn off the associated semiconductor power switches 5A and 5B for a short turn-off period of less than 1 millisecond, depending on the configuration and adjusted capacitance of capacitor C. Turn-off times of 2 to 5 microseconds can even be achieved. Figure 10A In the exemplary embodiment shown, the drive circuit 6 includes a single IGBT driver ICIED020 / 12-B2 manufactured by Infineon Technologies. Other drive circuits 6 may also be used, particularly ASICs.

[0090] In one possible implementation, the current rise rate sensor assembly 4 can also be implemented by another component sensor coil, particularly by a resistor with corresponding local measurement circuitry, adapted to directly generate a voltage U corresponding to the rate of rise of the current I flowing through the corresponding sensing resistor. This resistor may include an NTC or PTC resistor. In one possible implementation, the resistance of the resistor 4 used may be temperature-dependent. The temperature-dependent resistance of the resistor 4 can be individually configured to physically limit the associated semiconductor power switch 5.

[0091] Figure 10B , Figure 10A Different overvoltage scenarios that can be detected by the overvoltage detection circuit 12 of the protection device 1 according to the present invention are illustrated. The applied supply voltage U AC It is sinusoidal and includes frequencies, for example, 50 to 60 Hz. Figure 10B In the example shown, transient TR may appear in the applied voltage signal, which could damage the connected load 9. These high-frequency transients or frequency spikes can be reliably detected by the overvoltage detection circuit 12 via the analog comparator 36.

[0092] Figure 10A This indicates the received power supply voltage U AC The slow drift can also damage the connected load 9. This load frequency drift can be addressed by an overvoltage detection circuit 12 and a digital comparator 34 implemented via an analog-to-digital converter (ADC) 17 and a microprocessor 8A in the control unit 8.

[0093] Therefore, the overvoltage detection unit 12 of the protection device 1 can handle different types of overvoltage scenarios, especially Figure 10B The high-frequency transient TR shown and Figure 4 The low voltage drift shown.

[0094] exist Figure 9 In the illustrated embodiment of the overvoltage detection circuit 12, the overvoltage detection circuit 12 includes two main paths: a fast signal path for detecting the transient TR in the received supply voltage and a path suitable for detecting the received AC supply voltage U. AC The slower signal path with low drift in the middle.

[0095] The sensitivity of the overvoltage detection circuit 12 can be controlled by setting the threshold value TH1 of the digital comparator 34 in the slow control path and by setting the threshold voltage TH2 of the comparator of the Schmitt trigger 36 in the fast control path of the overvoltage detection circuit 12. These threshold values TH1, TH2 are in possible implementations controlled by software executed by the microprocessor 8A. In possible implementations, the overvoltage detection software executed by the microprocessor 8A can also control the sampling rate of the analog-to-digital converter 17. These parameters can be pre-set and configured or controlled to some extent by a remote high-level controller connected to the control unit 8 of the protection device 1. In possible implementations, the overvoltage detection software can be stored in a program memory of the control unit 8. The overvoltage detection software can be customized and adapted to specific use cases, in particular to the amplitude of the supply voltage U AC and to the type of load 9 connected to the output terminals 3 of the protection device 1. The type of load 9 connected to the output terminals 3 of the protection device 1 can include a resistive load, a capacitive load or an inductive load, in particular an AC motor. For different types of loads, different customized software programs or routines can be stored as firmware in a memory of the control unit 8. In another implementation, different customized overvoltage detection programs or routines can also be loaded from a database connected to a program memory of the control unit 8 by a data interface. The data interface can be connected to a remote database or server over a data network. For example, a user can select the basic type of the connected load 9, e.g. a resistive load or an inductive load, and the amplitude of the supply voltage U AC provided by the supply network PSN, so that the associated fitted overvoltage detection software is loaded or activated to perform the overvoltage detection procedure. In this way, a high degree of flexibility is achieved, allowing flexible and fast adaptation of the overvoltage detection to different use cases and operating scenarios. In possible implementations, the protection device 1 comprises a user interface adapted to input the basic parameters, e.g. the type of the connected load 9 and the amplitude of the supply network PSN, to select the associated fitted overvoltage detection program or routine to perform the overvoltage detection. In possible implementations, these parameters can be set in a configuration mode of the protection device 1. The user can further adjust the shutdown period, e.g. by adjusting the capacitance of the capacitor C within the DESAT rectifier stage 40 shown in Fig. 2. Furthermore, the threshold values of the comparators 34, 36 of the overvoltage detection circuit 12 can be configured. The configuration values can be stored in a configuration memory of the control unit 8. Figure 11A

[0096] Figure 11B Figure 11A A shutdown performed by the protection device 1 in case a transient is observed in the received supply voltage is schematically shown in Fig. 3. In the example shown in Fig. 3, the supply voltage U Figure 11B ​​As can be seen, the transient TR can exceed a predetermined threshold to trigger an automatic turn-off of at least one semiconductor power switch 5 within the power supply path 10, thereby interrupting the load current I Figure 11A flowing to the load 9 as shown. L The detection of the transient TR and the turn-off of the load current I L between them in the preferred embodiment comprises less than 1 millisecond. Figure 5 The turn-off period shown can be as low as a few microseconds. One advantage of the protection device 1 according to the present application is that the turn-off of the power supply path 10 can occur at any time and is not limited to a turn-off at a zero voltage crossing of the received AC supply voltage U AC . Moreover, the turn-off period provided by the overvoltage detection according to the present application can be extremely short, i.e. even as low as a few microseconds. The very fast turn-off of the load current I L protects the load 9 and also increases its operational life.

[0097] The protection device 1 according to the present application can be integrated into the housing of a device. The device can comprise protruding electrical contacts at the input terminals 2 which are adapted to be plugged into corresponding slots of a hybrid power bus of a busbar system. In one possible embodiment, the protection device 1 comprises ​ three input terminals 2-1, 2-2, 2-3 as shown and has three corresponding protruding electrical contacts which can be plugged into corresponding slots of a hybrid bus of a busbar system. In a possible embodiment, the protection device 1 can also be integrated into a NH fuse housing.

[0098] The protection device 1 can be connected to a busbar of a busbar system directly through its input terminals 2 or indirectly through an adapter device. The load protection device 1 can also be mounted directly or indirectly to a DIN rail or a top hat rail or a conventional busbar through an adapter.

Claims

1. A protection device (1) for protecting an electrical load (9), The protection device (1) comprises: - at least one input terminal (2) adapted to receive a supply voltage; - at least one semiconductor power switch (5) in the power supply path (10), which is connected in series with an associated input terminal (2), the electrical load (9) connected to the output terminal (3) of the power supply path (10) receiving an electrical load current I through the power supply path (10) L ; The protection device (1) further comprises: - a control unit (8) with a microprocessor (8A) adapted to control a drive circuit (6) of the protection device (1) to turn on or turn off the at least one semiconductor power switch (5) arranged in the supply path (10) in response to a received switching command (CMD), the drive circuit (6) having a low voltage side (6A) and having a high voltage side (6B), The protection device (1) further comprises: at least one overvoltage detection circuit ODC (12) connected with the input terminal (2) or the output terminal (3) of the associated supply path (10) of the protection device (1) and adapted to detect an overvoltage condition at the respective supply path (10) of the protection device (1) and to directly control the drive circuit (6) to turn off the at least one semiconductor power switch (5) arranged within the associated supply path (10) by a control line (13) when the overvoltage condition is detected by the overvoltage detection circuit ODC (12) to provide the connected electrical load (9) with protection from overvoltage, the control line (13) being connected with a first input of an AND gate (14) connected with a driver input (IN) of the low voltage side (6A) of the drive circuit (6), wherein the overvoltage detection circuit ODC (12) comprises a digital comparator COMP1 (34) implemented in the microprocessor (8A) of the control unit (8) and adapted to compare a low pass filtered signal output by an analog-to-digital converter ADC (17) of the overvoltage detection circuit ODC (12) with a first adjustable digital threshold value TH1 to detect a low frequency drift of the voltage at the respective terminal (2; 3) of the protection device (1) and further adapted to generate a high logic signal when a low frequency drift is detected, wherein the generated high logic signal is applied to a second input of the AND gate (14).

2. Protection device (1) according to claim 1, wherein The control unit (8) is connected with a user interface or a system level controller of an automation system to receive the switching command (CMD).

3. Protection device (1) according to claim 1 or 2, wherein The at least one semiconductor power switch (5) provided in the power supply path (10) comprises an IGBT or a power MOSFET having a blocking voltage exceeding the normal operating voltage of the supply voltage U IN applied to the input terminal (2) of the power supply path (10), wherein a control gate (21) of the at least one semiconductor power switch (5) is directly connected to a driver output (OUT) of the high voltage side (6B) of the drive circuit (6).

4. The protection device (1) according to claim 1, wherein The protection device (1) comprises three input terminals (2-1, 2-2, 2-3) and three output terminals (3-1, 3-2, 3-3) interconnected via associated supply paths (10-1, 10-2, 10-3), wherein for each supply path (10-1, 10-2, 10-3) an associated overvoltage detection circuit ODC (12-1, 12-2, 12-3) is provided, wherein the overvoltage detection circuit ODC (12-i) is connected to the input terminal (2-i) and / or the output terminal (3-i) of the respective supply path (10-i).

5. The protection device (1) according to claim 1, wherein The drive circuit (6) is adapted to turn off the at least one semiconductor power switch (5) arranged in the power supply path (10) within a turn-off period of less than 1 millisecond, the turn-off period being defined by signal propagation delays along a first control line (13, 20) and along internal circuitry of the drive circuit (6).

6. The protection device (1) according to claim 3, wherein The signal propagation delays of the internal circuitry of the drive circuit (6) between the following two are less than 200 nanoseconds: The driver input (IN) of the low voltage side (6A) of the drive circuit (6), The driver output (OUT) of the high voltage side (6B) of the drive circuit (6).

7. The protection device (1) according to claim 1, wherein Each overvoltage detection circuit ODC (12-i) connected with an input terminal (2) or an output terminal (3) of an associated power supply path (10-i) comprises: - a rectifier (27) adapted to rectify a voltage at the respective terminal (2; 3), and - an analog-to-digital converter ADC (17) adapted to convert the low pass filtered signal applied to the analog-to-digital converter ADC (17) into a digital signal applied to a digital comparator COMP1 (34) implemented in the microprocessor (8A) of the control unit (8) of the protection device (1) and adapted to compare the low pass filtered signal output by the analog-to-digital converter ADC (17) with a first adjustable digital threshold value TH1 to detect low frequency drift of the voltage at the respective terminal (2; 3) and further adapted to generate a high logic signal upon detection of low frequency drift.

8. Protection device (1) according to claim 7, wherein Each overvoltage detection circuit ODC (12-i) further comprises a fast analog comparator COMP2 (36), in particular a Schmitt trigger circuit, adapted to compare a rectified voltage output by the rectifier (27) with a threshold setpoint TH2 to detect overvoltage transients of the voltage of the respective terminal (2; 3) of the protection device (1) and further adapted to generate a logic enable signal to enable the drive circuit (6) to turn off the at least one semiconductor power switch (5) arranged in the associated power supply path (10) upon detection of an overvoltage transient by the fast analog comparator COMP2 (36).

9. The protection device (1) according to claim 8, wherein The logic signals generated by the digital comparator COMP1 (34) implemented in the microprocessor (8A) of the control unit (8) and the logic enable signals generated by the fast analog comparator COMP2 (36) of the overvoltage detection circuit ODC (12) are logically combined by the AND gate (14) of the overvoltage detection circuit ODC (12) to provide a logic voltage status signal indicative of a detected instantaneous voltage status of the respective terminal (2; 3) of the associated power supply path (10), wherein the logic voltage status signal is applied to the driver input (IN) at the low voltage side (6A) of the drive circuit (6).

10. Protection device (1) according to claim 8, further comprising an analog high-pass filter HPF (28) arranged between the rectifier (27) and the fast analog comparator COMP2 (36), the analog high-pass filter HPF (28) being adapted to perform a high-pass filtering of the rectified voltage output by the rectifier (27).

11. The protection device (1) according to claim 7, wherein The rectifier (27) of the overvoltage detection circuit ODC (12) is connected with the associated power supply path (10) via a potential separation circuit (26).

12. The protection device (1) according to claim 7, wherein The drive circuit (6) is adapted to provide a monitoring signal to the microprocessor (8A) of the control unit (8), the monitoring signal being adapted to inform the microprocessor (8A) about a current operating state of the drive circuit (6) and / or about a current switching state of the at least one semiconductor power switch (5).

13. The protection device (1) according to claim 8, wherein The threshold setpoint TH2 of the fast analog comparator COMP2 (36) of the overvoltage detection circuit ODC (12) is set by the microprocessor (8A) of the control unit (8) via a digital-to-analog converter DAC (38), wherein the threshold setpoint TH2 comprises a fixed threshold in a first operating mode of the protection device (1) and a moving threshold in a second operating mode of the protection device (1).

14. Protection device (1) according to claim 1, further comprising a load current sensor assembly (7) connected in series with the at least one semiconductor power switch (5) of the power supply path (10), wherein the load current sensor assembly (7) is adapted to continuously measure a load current I L flowing through the at least one semiconductor power switch (5) in the power supply path (10) to a connected electrical load (9) L wherein the measured load current I L is notified by the load current sensor assembly (7) to the microprocessor (8A) of the control unit (8) to determine an instantaneous load state of the electrical load (9) connected with the output terminal (3) of the respective power supply path (10).

15. The protection device (1) according to claim 14, further comprising: a current rise velocity sensor assembly (4) connected in series with said at least one semiconductor power switch (5) and said load current sensor assembly (7), said current rise velocity sensor assembly (4) being adapted to generate a voltage drop (AU4) corresponding to a current rise velocity of said load current I L from said input terminal (2) along said power supply path (10) via said current rise velocity sensor assembly (4) and said at least one semiconductor power switch (5) and said load current sensor assembly (7) to a respective output terminal (3) of said power supply path (10), L from said input terminal (2) along said power supply path (10) via said current rise velocity sensor assembly (4) and said at least one semiconductor power switch (5) and said load current sensor assembly (7) to a respective output terminal (3) of said power supply path (10), wherein said drive circuit (6) of said protection device (1) is adapted to detect an occurring overcurrent from said voltage drop (AU4) generated by said current rise speed sensor assembly (4) and a voltage drop (AU5) along said at least one semiconductor power switch (5) as a sum voltage (U ∑ ) directly applied to a driver input (DESAT) of a high voltage side (6B) of said drive circuit (6), and to automatically switch off said at least one semiconductor power switch (5) within a turn-off period of less than 1 millisecond upon detection of an overcurrent to provide protection from overcurrents. ∑ ) directly applied to a driver input (DESAT) of a high voltage side (6B) of said drive circuit (6), and to automatically switch off said at least one semiconductor power switch (5) within a turn-off period of less than 1 millisecond upon detection of an overcurrent to provide protection from overcurrents. wherein the turn-off period of less than 1 millisecond is defined by a signal propagation delay along a control signal loop, the control signal loop comprising a connection circuit connecting the current rise speed sensor assembly (4) with the driver input (DESAT) of the high voltage side (6B) of the drive circuit (6) and an internal circuit within the high voltage side (6B) of the drive circuit (6).

16. Protection device (1) according to claim 1, comprising: a first overvoltage detection circuit ODC1 connected with an input terminal (2) of an associated power supply path (10) and adapted to determine an instantaneous voltage state at the input terminal (2) and comprising: a second overvoltage detection circuit ODC2 connected with an output terminal (3) of an associated power supply path (10) and adapted to determine an instantaneous voltage state at the output terminal (3).

17. Protection device (1) according to claim 16, wherein the instantaneous voltage state at the input terminal (2) determined by the first overvoltage detection circuit ODC1 and the instantaneous voltage state at the output terminal (3) determined by the second overvoltage detection circuit ODC2 are processed to determine an instantaneous overall voltage state at both terminals (2; 3) of the protection device (1), which are logically combined by a logic circuit to trigger the drive circuit (6) of the protection device (1) to automatically turn off the at least one semiconductor power switch (5) of the protection device (1) upon detection of an overall overvoltage state at both terminals (2; 3) of the protection device (1).

18. The protection device (1) according to claim 15, wherein The current rise speed sensor assembly (4), the at least one semiconductor power switch (5) and the load current sensor assembly (7) are connected in series along the power supply path (10) and form a secondary current path (1B) arranged between the input terminal (2) and the output terminal (3) of the protection device (1), wherein a primary current path (1A) of the protection device (1) comprising a controllable mechanical switch MSW is arranged between the input terminal (2) and the output terminal (3) of the protection device (1), the primary current path (1A) being connected in parallel to the secondary current path (1B).

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