Methods, apparatuses, and devices for surge protection

Abstract

This disclosure relates to methods, devices, and apparatuses for surge protection. The surge protection device (1) comprises: a detection unit (2) for generating a detection signal (d) indicating the occurrence of a surge pulse caused by a power surge in the power system (10); a bypass unit (3) having a bypass path (34) for bypassing the pulse according to the detection signal (d); and an absorption unit (4) for suppressing the pulse after it has been bypassed by the bypass unit (3).

Description

Technical Field

[0001] The present invention relates to a surge protection device and a surge protection method for suppressing surges occurring in a power system having at least first and second power lines for supplying power.

[0002] Furthermore, the present invention relates to an apparatus comprising surge protection devices and electrical equipment, the electrical equipment being designed to be powered via a first power line and a second power line of an electrical system. Background Technology

[0003] In power lines of an electrical system, excessive and sudden increases in electrical quantity constitute a frequent and critical phenomenon, most notably excessive and sudden increases in voltage and current. This sudden increase in electrical quantity is generally referred to as a “surge.” Surges can occur due to sudden events, particularly lightning strikes, short circuits between power lines, or the sudden activation of additional loads. Surge protection devices (SPDs) are widely used to protect electronic equipment from surges. SPDs are designed to protect loads from voltage and / or current surges. In most cases, one of two strategies is implemented for surge protection: series protection or parallel protection. Series protection typically utilizes a high impedance connected in series with the load to be protected to block or limit the surge current, while parallel protection aims to guide the dangerous surge current through an impedance connected in parallel with the load to be protected, preferably into an absorption element.

[0004] In the field of power rectifier technology, the use of mains filters (hereinafter referred to as "mains filters" or "large mains filters") including boost chokes with large volume and impedance is prior art in order to suppress PWM-induced interference (PWM ripple) generated by the rectifier from entering the power (i.e., transmission) lines of the power system, especially in the case of AC-DC converters that rectify AC mains voltage to DC voltage. The primary desired effect of large mains filters is to prevent PWM-generated interference from entering the power lines ("filter function"). However, a significant side effect of large mains filters is that, in the event of a surge event in the power lines, the filter also limits the surge voltage and / or surge current acting on and affecting the rectifier, thereby protecting the rectifier from overcurrent and overvoltage ("protection function"). Surge pulses are suppressed or absorbed in the mains filter on the AC side of the rectifier.

[0005] A significant trend affecting the protection capabilities of AC-side power filters is the increasing use of multi-stage topologies (i.e., rectifiers with three levels and more stages, "multi-stage active rectifiers"). This results in reduced PWM-induced interference, allowing for smaller power filters and smaller boost chokes in terms of size and impedance. While these reductions save on cost and components and are therefore highly desirable, fewer chokes mean that, on the downside, the voltage and current acting on the rectifier can reach higher values ​​more quickly in the event of a mains surge. Surges are no longer adequately absorbed in the mains filter. Consequently, protection through the mains filter is reduced, which is problematic in many practical situations because multi-stage active rectifiers are particularly sensitive to overvoltages. Therefore, adequate surge protection is required in modern systems that include multi-stage active rectifiers, often even in addition to the mains filter that may already be present.

[0006] On the one hand, surge protection for multi-stage active rectifiers, and for various other electrical components requiring surge protection, needs to respond quickly to overvoltages and overcurrents. On the other hand, surge protection devices should not be overly sensitive. In reality, there are situations where only short (<1μs) overvoltage bursts occur, such as in mains power lines. Even with only a small mains filter, such pulse trains are very short, making a significant voltage increase invisible on the rectifier side of the mains filter. Therefore, in such cases, rectifier protection or deactivation is unnecessary. The IEC 61800-3 and IEC / EN 61000-6-2 standards even explicitly allow for short pulse trains with low energy. Therefore, surge protection devices (SPDs) are needed to achieve a precise balance between sensitivity, speed, and robustness. Unfortunately, existing SPDs are either slow and insensitive, or fast and oversensitive, resulting in unsatisfactory protection behavior.

[0007] Therefore, there is a need for improved surge suppression, especially surge suppression that balances the need for both high sensitivity and robustness. Summary of the Invention

[0008] For the surge protection device mentioned at the beginning, this objective is achieved in the following manner: providing a detection unit that can be connected to the first and / or second power line to generate a detection signal indicating the occurrence of a surge-induced pulse in the power system; providing a bypass unit having a first bypass terminal that can be connected to the first or second power line, a second bypass terminal connected to the first bypass terminal via an electrical bypass path, and a trigger terminal designed to receive the detection signal generated by the surge detection unit, wherein the electrical bypass path can switch from a resistive disconnected state to a conductive state in response to the detection signal; and providing an absorption unit having a first absorption terminal that can be connected to the second bypass terminal of the bypass unit, the absorption unit being designed to suppress surges and thus allowing surge protection when the bypass path is in a conductive state.

[0009] The surge protection scheme according to the present invention offers several advantages. By monitoring the amount of energy transmitted by the pulse, the present invention achieves a coordinated and targeted protection scheme, as well as a new perspective on systems requiring surge protection. Preferably, by defining a minimum energy threshold that must be exceeded by the pulse to limit it to energy-rich pulses, negligible fluctuations are automatically ignored without loss of sensitivity or response speed.

[0010] Advantageous embodiments of the surge protection device according to the invention are provided in dependent claims 2 to 7.

[0011] As mentioned earlier, the present invention also relates to an apparatus comprising surge protection devices and electrical equipment, and a method for surge protection, wherein the electrical equipment is designed to be powered via first and second power lines of a power system. The method corresponds to the aforementioned apparatus and includes the following steps: generating a detection signal by a detection unit indicating the occurrence of a surge-induced energy pulse in the power system; providing a bypass unit having a first bypass terminal connected to the first or second power line, a second bypass terminal connected to the first bypass terminal via an electrical bypass path, and a trigger terminal designed to receive the detection signal generated by the surge detection unit, switching the electrical bypass path from a resistive open state to an electrically open state in response to the detection signal; and suppressing and thus allowing the prevention of the surge when the bypass unit is in the open state by means of an absorption unit connected to the second bypass terminal of the bypass unit.

[0012] Advantageous embodiments of the surge protection method according to the invention are provided in dependent claims 14 and 15. Attached Figure Description

[0013] The following reference Figures 1 to 7 To describe the invention in more detail, Figures 1 to 7Illustrative and non-limiting advantageous embodiments of the invention are shown by way of example. The specific examples described herein are for illustrative purposes only and are not intended to limit the embodiments. As follows:

[0014] Figure 1 This is a first simplified working example of the present invention.

[0015] Figure 2 This is a circuit diagram of a sub-component implementing the present invention.

[0016] Figure 3a and 3b These are two particularly advantageous embodiments of the present invention.

[0017] Figure 4 This is the first device of the surge protection device (SPD) and rectifier according to the present invention.

[0018] Figure 5 This is a second device of the surge protection device (SPD) and rectifier according to the present invention.

[0019] Figure 6 The third device of the surge protection device (SPD) and the three-stage rectifier according to the present invention, and

[0020] Figure 7 This is a flowchart describing the sequence of steps for carrying out the present invention. Detailed Implementation

[0021] Figure 1 The application of the invention to an electric power system 10 is shown in a simplified form. The similarly simplified electric power system 10 has a first power line A and a second power line B, preferably supplying power to an electrical load 5 ( Figure 1 (Not shown in the diagram, hereinafter also referred to as "load") supplies electricity. The (electrical) load supplied by power lines A and B can be a single load or a combination of multiple loads 5, such as a single or multiple electric machines or devices or computing units or rectifiers, etc. The power system 10 to which this invention can be applied can be a power grid for power distribution, and in addition to Figure 1 In addition to the lines shown, there may be one or more different types of power sources, or combinations of electrical storage devices and / or loads, and / or other power systems fed into the power system 10 shown. Power lines A and B can provide AC voltage or DC voltage. Furthermore, as will be explained in detail later (especially). Figure 4 and 5As shown, three or more power lines A, B, and C can also be provided, which is typical in AC systems. All of these situations represent potential use cases where power surges may occur, and appropriate surge protection is required. For this purpose, the surge protection device (SPD) 1 according to the invention can be installed between power lines A and B. In particular, the SPD 1 according to the invention can be provided as a retrofitted object, and thus independent of the power system 10 or its subsequently applied load 5.

[0022] As previously discussed, a power surge occurs when the voltage within an electrical system, such as power system 10, suddenly increases. This increase can occur due to various factors, including lightning strikes, grid switching operations, or faults in electrical equipment within power system 10, as illustrated. Surges can pose significant hazards and may even damage the load 5 supplied through power system 10. In severe cases, surges can cause fires, electric shocks, or damage to critical electronic components. Figure 1 In the power system 10 shown, power surges can take different forms, such as bidirectional oscillations between power lines A and B, or unidirectional electrical pulses, voltage or current pulses, etc., in lines A and / or B.

[0023] To counteract these situations, SPDs should perform precise balancing actions. On one hand, SPDs are required to react quickly to overvoltages and overcurrents to effectively shield sensitive devices. This necessitates high sensitivity to rapidly detect and respond to transient events. However, excessive sensitivity can lead to unnecessary tripping. Even small voltage fluctuations, such as those caused by switching operations in the power grid, can trigger an oversensitive SPD, thus unnecessarily interrupting power and potentially disrupting operation. Such erroneous tripping can be highly destructive, especially in safety-critical systems. This inherent contradiction represents a significant challenge in SPD design.

[0024] To address these issues and improve upon the surge protection concepts known in the prior art, namely, to allow for the simultaneous provision of surge protection with the correct amount of sensitivity and robustness, the present invention proposes a surge protection device 1 equipped with a detection unit 2, a bypass unit 3, and an absorption unit 4. The detection unit 2 is used to detect surge events, the bypass unit 3 is switched according to the result of the detection unit 2, and the absorption unit 4 is used to prevent surges when the bypass unit is switched to the conducting state according to the result of the detection unit 2.

[0025] exist Figure 1In this embodiment, the detection unit 2 of SPD 1 is detachably connected to the first power line A and the second power line B. The detection unit 2 is capable of generating a detection signal d indicating the presence of an energy-rich pulse in the power system 10. In a power system 10 similar to that shown, it has been found that the most significant cause of energy-rich pulses to date is power surge. Therefore, if an energy-rich pulse is detected, a power surge is also automatically detected. However, unlike existing technologies, establishing monitoring of the power system to prevent impacts on the monitoring of electrical energy transmitted by pulses in the power system demonstrates a significant improvement in results achieved when a balance is struck between sensitivity, response speed, and robustness.

[0026] There are a number of methods for implementing detection unit 2. As mentioned above, the key point is that detection unit 2 is able to detect the presence of pulses in power lines A and B, and is able to monitor the energy transmitted by the pulses.

[0027] To sense and detect the presence of a pulse, a threshold for the rate of change of, for example, the voltage between line A and line B or the current flowing through line A and / or B can be defined, above which the presence of a pulse can be assumed. For example, in the case of a sinusoidal voltage, it is well known that when the sinusoid is assumed to be its arithmetic mean, the steepest slope occurs, representing the highest rate of change of the voltage. This slope can usually be pre-calculated such that a rate of change significantly exceeding this maximum rate of change is an indication of the presence of a pulse. For example, for a 230V RMS, 50Hz voltage transmitted by lines A and B, the peak voltage is approximately 325V. By differentiating this sinusoidal voltage and considering the peak value of the cosine function, the maximum rate of change is calculated to be approximately 100,000 volts per second. This value represents the fastest possible voltage change in the power grid under the ideal conditions assumed above. Therefore, the rate of change threshold indicating a pulse can be chosen to be 150,000 volts per second or 200,000 volts per second. Typically, pulse detection in electrical systems can be achieved through various methods, including threshold detection, edge detection, pulse width discrimination, pulse shape analysis, frequency domain analysis, and the use of application-specific integrated circuits (ASICs). The optimal method depends on the specific characteristics of the pulse and system requirements, such as desired speed, accuracy, and noise immunity. Numerous documents on this topic have been published, such as US2023 / 0108660A1. Therefore, for example, the presence of a pulse can be detected upon the first exceeding of the rate of change threshold (pulse rise), and it can be assumed that the pulse continues until the second exceeding of the rate of change threshold (preferably, pulse fall).

[0028] From a theoretical point of view, monitoring the energy transmitted by electrical pulses in power system 10 (as shown) involves directly or indirectly capturing the voltage waveform of the voltage drop between power lines A and B, and directly or indirectly capturing the current waveform of the current flowing through one of power lines A and B. The instantaneous power waveform can be calculated by multiplying the instantaneous voltage and current values ​​at each point in time, as is known from basic electrical engineering. Integrating the instantaneous power over the pulse duration generates the energy transmitted by the pulse, typically expressed in joules. Mathematically, this is represented as... Where E is energy, V(t) is the voltage between lines A and B as a function of time, and I(t) is the current as a function of time. Typical energy thresholds are, for example, 10 joules, 20 joules, 50 joules, or 100 joules, above which the pulse can be considered energy-rich. If the pulse energy exceeds such a threshold, the detection signal d of the present invention can take a first state indicating the presence of an energy-rich pulse, which allows the bypass unit 3 (i.e., the electrical bypass path 34, explained later) to be switched on. A second state of switching the bypass unit 3 can be assumed not to be allowed if the energy threshold is not exceeded.

[0029] Therefore, monitoring the presence of an energy-rich pulse and generating a detection signal d based on it can be understood as corresponding to detecting the presence of a pulse, such as an electric, magnetic, or electromagnetic pulse in one or between electric power lines, which can be performed by an appropriate method for pulse detection, and corresponding to monitoring the energy transmitted by the pulse, i.e. during the pulse occurrence, as above, an appropriate method can also be selected for it.

[0030] To implement pulse detection and energy monitoring in practice, detection unit 2 can be implemented digitally or analogically. In the case of an analog implementation, a capacitive element, such as a capacitor, can be provided, which can combine the two aspects of pulse detection and energy monitoring in a particularly advantageous and efficient manner. The capacitor is designed to integrate the rate of change of voltage and convert it into a current, which can be used as a detection signal d, indicating the presence of a pulse and the presence of sufficient energy. Bypass unit 3 is designed to be switched only when sufficient current has flowed through such a capacitor (typically, as explained later, the gate capacitance of the switch needs to be charged), such that the required current amount and therefore the level of the detection signal d, combined with its duration, represent the energy transmitted by the pulse. The current required to switch bypass unit 3 can be selected such that it corresponds to a specific energy threshold. When using a capacitor, possible current thresholds could be 0.001 A, 0.005 A, 0.01 A, 0.05 A, 0.1 A, 0.5 A, 1 A, 10 A, or another suitable current threshold. In a preferred embodiment, it may be necessary for such a current to be present for a specified time, such as 1 μs, 5 μs, 10 μs, 100 μs, 0.5 ms, 1 ms, 10 ms, 100 ms, 0.5 seconds, or 1 second, etc. Another possibility for analog implementation is to use inductive elements, such as inductors, and use the same principle to transmit the current through line A or B as a detection signal d to the sole of the foot in a different manner. The integral of the rate of change can preferably be scaled to obtain a detection signal d indicating the presence of a pulse and the energy transmitted by the pulse. In the case of a capacitor, the integral can be automatically scaled by the capacitance of the capacitor; in the case of an inductor, this scaling can be based on its inductance value. However, when the rate of change of voltage is integrated, the integral can also be scaled by the voltage, or when the rate of change of current is integrated, the integral can also be scaled by the current to generate a meaningful signal.

[0031] In a digital implementation, analog measurement signals of voltage and current can be fed into an analog-to-digital converter (ADC). Current and voltage measurements can be performed using appropriate voltage and current measurement devices, such as voltage and current probes, or voltage dividers switched in series with operational amplifier circuitry to provide a voltage-proportional signal, and / or current transformers can be used to measure inrush current, where the transformer's output is rectified and smoothed to provide a DC voltage proportional to the inrush current. Dedicated energy measurement devices can also be used. The ADC samples these signals, converting them into digital values ​​that can be processed by a microcontroller or digital signal processor (DSP). To also detect voltage changes, i.e., dv / dt changes, with sufficient accuracy and speed, fast voltage measurements with bandwidth in the 1MHz range and an effective resolution of 8 bits have been developed to generate convincing results that ensure robust surge / fault detection across the entire grid input range. The microcontroller or DSP can then be programmed to detect pulses generated due to a surge based on the amplitude, duration, or frequency content of the signal, multiplying and integrating them to obtain the energy transmitted by the pulses, and thereby generating the detection signal d.

[0032] Furthermore, the bypass unit 3 of the surge protection device 1 according to the present invention has a first bypass terminal 31 detachably connected to the first or second power lines A, B, a second bypass terminal 32 connected to the first bypass terminal 31 via an electrical bypass path 34, and a trigger terminal 33 designed to receive a detection signal generated by the surge detection unit 2. In response to the detection signal d generated by the detection unit 2, the electrical bypass path 34 can switch from a resistive disconnected state to a conductive state.

[0033] Finally, the absorption unit 4 according to the invention has a first absorption terminal 41 capable of being connected to the second bypass terminal 32 of the bypass unit 3, such that it can prevent surges when the bypass path 34 is in a conducting state, i.e., redirect the current caused by the surge, so that it can not damage the load 5, and further store the energy transferred by such current or convert it into heat in the resistor. Therefore, preventing a surge can be understood as protecting, for example, the load 5 from the surge, or as bypassing a surge from or from the portion of the load 5 that needs protection. The absorption unit 4 includes an absorption element, which can take the form of a resistive element, a rheostat, a capacitor, a resistor, or any combination thereof. Those skilled in the art of power electronics know the possible choices for preventing potentially dangerous currents or voltages. In the preferred embodiment, also as Figure 1 As shown, the absorption unit 4 is only connected to the bypass unit 3, and therefore is no longer connected to power lines A and B. In this way, the absorption unit 4 can be separated from the power system 10.

[0034] The surge protection scheme according to the invention offers several advantages, particularly regarding improved reliability and prevention of various types of surges. By utilizing the amount of energy transmitted by the pulse, the invention achieves a coordinated protection scheme that can be fine-tuned to the details of any given use case, resulting in an optimized balance between sensitivity and robustness. In particular, by defining a minimum energy threshold that must be exceeded by the pulse to limit it to energy-rich pulses, negligible fluctuations no longer trigger surge detection, while rapid and accurate detection and response to surge pulses remain possible.

[0035] Figure 2 A detailed electronic schematic diagram of a possible implementation of the components of the SPD according to the invention is shown. The detection unit 2 includes a capacitive element that converts the change in capacitance into a current as a detection signal d at an integral rate. It is generally advantageous to ensure that there are no additional resistances and / or impedances and / or capacitances and / or inductances in the detection unit 2 that interfere with or delay the response to surge events detected by the capacitive element (capacitor) if the capacitive element (i.e., capacitor) is directly connected to the bypass unit 3 and thus to the bypass path (i.e., there are no other electrical components between the capacitor and the bypass unit 3). The electrical bypass path 34 of the bypass unit 3 includes switching devices in the form of two diodes D1, D2 and a thyristor T1, electrically connected to the first and second bypass terminals 31 and 32. Furthermore, in Figure 2 In bypass unit 3, inductor L1 is positioned between the first and second bypass terminals 31 and 32, connected in series with the switching device. Inductor L1 is only used to protect the switching device from overcurrent, and therefore is not based on... Figure 2 The absorption unit 4 is a necessary component for the implementation. It is made of a variable resistor R1, but it can also be implemented differently as described above.

[0036] Generally, the electrical bypass path 34 of the bypass unit 3 includes switching devices for electrically connecting the first and second bypass terminals 31 and 32. These switching devices can be selected from a group including TRIACs (transistors for alternating current), SCRs (silicon controlled rectifiers), thyristors, etc., which are well known in power electronics. In particular, thyristors provide efficient power control, are cost-effective, and have a long lifespan. Each element in this group has a gate electrode connected to the trigger terminal 33 of the bypass unit 3. This configuration allows the gate electrode to receive and respond to the detection signal d. Since the gate capacitance of the switching device must be charged during the switching process, the conductive current generated by the detection unit 2 as the detection signal d is also an indication of the energy transmitted by the pulse of the surge event.

[0037] exist Figure 2In the schematic diagram shown, the gate of the thyristor is connected to one of the phases via a combination of a capacitor and a diode. Therefore, no additional ignition transformer or control from the signal side is required. In the event of a surge event between two phases, the capacitor experiences a high dv / dt, which causes current to flow into the gate of the thyristor to charge it. When the thyristor gate voltage is sufficiently high, taking 5 to 8 μs depending on the surge level, the thyristor begins to conduct, and the rheostat then limits the phase-to-phase voltage, thus protecting the multi-stage structure. Once the current through thyristor T1 becomes negative (after <30 μs), thyristor T1 begins to automatically turn off, thus interrupting the connection to the limiting rheostat again. The unwanted current from the surge is then discharged, and normal operation can be resumed. To handle surge events of different polarities, it is preferable to provide a second surge in the opposite direction. Figure 2 The circuit, that is, between phase B and phase A, and vice versa. For example, to protect the three phases of a three-phase power system 10, a total of six thyristor-rheostat-inductor combinations are required. The rated voltage of the charging capacitor is preferably at least 500V to meet the requirements regarding the grid voltage. In order to achieve according to Figure 2 For this circuit, a 1000V X7R capacitor can be selected. Preferably, the thyristor also has an appropriate rated voltage, thus enabling it to handle current pulses up to 1000A. As mentioned above, the current rise time of this thyristor is limited, therefore an additional inductor L1 (e.g., a 1μH inductor or an inductor with higher inductance) limits the di / dt that occurs in the current path to protect the thyristor T1.

[0038] To further explain the concept of the present invention, Figure 3a and 3b An embodiment clearly illustrates the load 5 to be protected. According to... Figure 3a In this configuration, SPD 1 and load 5 are strictly separated. All components of SPD 1 (detection unit 2, bypass unit 3, absorption unit 4) are contained within SPD 1 and therefore do not intersect with load 5. Conversely, Figure 3b A particularly advantageous embodiment of the invention is shown, wherein the load element, or possibly a series of elements, is used to suppress surges. It has been found that in many practically relevant applications, the load 5 includes elements that need to be protected from surges, and also includes elements that can be used to prevent surges. In any case, using elements present in the load 5 reduces the number of components and cost. The following will explain in detail the... Figure 3b An important example of an embodiment is the use of an output capacitor for a rectifier, such as a DC link capacitor placed on the output side of an AC / DC converter. Other examples include the use of a grounding resistor for a motor, etc. According to... Figure 3bIn this embodiment, the bypass path 34 of the bypass unit 3 is therefore partially parallel to the load, i.e., parallel to those components in the load 5 that need protection, such as sensitive switches. The bypass path 34 thus extends from the first bypass terminal 31 to the absorption element in the load 5. In this case, it is also conceivable that the surge protection device 1 is provided as an integral part of the electrical load 5, and is therefore already included in the production of the load 5 and preferably not removable from the electrical load 5. Thus, in this preferred embodiment, the load 5 includes internal elements that can be used as absorption elements, which may be a DC bus capacitor on the output side of the load 5, or a resistor in the load 5, or a capacitor inside the load 5, which is preferably robust to surges and therefore does not require protection, and the internal elements are used as absorption elements in the absorption unit to accept surges and protect the rest of the load, thereby suppressing surges.

[0039] Figure 4 Another particularly advantageous embodiment of the invention is shown, wherein the first device of the surge protection device 1 according to the invention is combined with a three-phase rectifier.

[0040] In technical applications involving three-phase rectifiers, particularly bidirectional AC-DC converters with a two-stage topology, it is existing technology to place a mains filter (also known as a "large mains filter") between the mains power and rectifier power lines, including a boost choke with a large volume and impedance. In this case, the primary function of the mains filter is to suppress mains interference from the rectifier to the mains power that causes PWM ("filter function"). Additionally, a positive side effect of the mains filter is that it also limits current increases and phase-to-phase voltages acting on the rectifier's semiconductor switches, thus protecting the semiconductor switches from overcurrent and overvoltage in the event of voltage surges in the mains power line ("protection function"). Surge pulses are therefore absorbed in the "large power filter" on the AC side.

[0041] As previously discussed, the use of multi-stage topologies (3L and more) in bidirectional AC-DC converters (hereinafter referred to as "multi-stage active rectifiers") is gaining increasing popularity, allowing for a significant reduction in the size and impedance of power supply filters and boost chokes to achieve "filter functionality." This reduces costs, improves form factor, and increases the overall efficiency of the devices that convert AC voltage to DC voltage and vice versa. However, this reduction in filter components means a deterioration in protection, allowing current in the semiconductors to reach critically high levels during surge events, which could damage the semiconductors. If surges in the mains filter are no longer adequately absorbed, dedicated surge protection must be implemented. However, in the case of two-level converters, additional surge protection is also reasonable, especially if a reduction in the size of filter components such as boost chokes is desired.

[0042] exist Figure 4 The diagram illustrates how the surge protection device 1 according to the invention can be used to protect a rectifier in situations similar to those outlined above. Figure 4 In the illustrated scheme, an active bidirectional AC-DC converter, preferably a multi-stage converter, serves as load 5, supplying AC voltage from a three-phase power system 10 comprising lines A, B, and C. Load 5 is designed to convert the AC power supply voltage supplied by the first, second, and third power lines A, B, and C into a rectified DC voltage UDC. A mains filter 15 with chokes L1, L2, L3 and capacitors C1, C2, C3 is provided upstream of load 5. To protect load 5 from surges even using only small boost chokes L1, L2, L3, a series of SPDs 1A, 1B, 1C can be installed between the mains filter 15 and lines A, B, and C. Figure 4 As shown, an SPD can be provided for each pair of lines (A, B), (A, C), (B, C)... Due to the location of the SPD between the mains filter 15 and lines A, B, C, compared to the case where the SPD device is located between the mains filter 15 and the load 5 (which is also conceivable), according to... Figure 2 In the implementation of this method, the dead time until the SPD becomes active (e.g., until the rheostat becomes active) can be significantly reduced.

[0043] However, in the case where the SPD device according to the invention is located between the mains filter 15 and power lines A, B, and C, it can achieve... Figure 5 Another particularly advantageous embodiment of the invention is shown. Figure 5 The AC-DC converter 5, preferably a bidirectional multi-stage converter, includes at least one DC bus capacitor C on its output side in the illustrated case. DC1 C DC2 This is used to output the rectified DC voltage UDC. It's worth noting that the implementation is based on... Figure 3b The concept of DC bus capacitor C DC1 C DC2 These are used as absorption elements within the corresponding absorption units 4A and 4B to prevent power surges. It should be mentioned that, in the case where detection units 2A, 2B… are installed between the mains filter 15 and the power system 10, a DC bus capacitor C is also conceivable. DC1 C DC2 It is used as an absorption element. If the induced PWM interference is sufficiently small, it is even conceivable to completely eliminate the power supply filter, as the SPD according to the invention provides sufficient protection. For clarity, in Figure 5 Only two SPs are shown, but again, in a preferred manner, corresponding SPDs can be provided for all transmission line pairs.

[0044] Using according to Figure 2 The implementation of the SPD but using DC bus capacitor C DC1 C DC2 replace Figure 2 With the variable resistor R1, the implementation and component operation can be significantly reduced. Thus, only two thyristors and one ignition transformer are needed. Therefore, each multi-stage phase of the rectifier is protected by two thyristors to prevent p. The energy of the surge pulse is directly compensated to the DC link.

[0045] Figure 6 A surge protection device (SPD) according to the invention and another device for a multi-stage inverter as load 5 are shown. For simplicity, only one branch of the inverter is shown for only one phase A of the power system 10 supplying power to the inverter. While detecting and reacting to the surge, the MOSFETs M1…M6 of the multi-stage structure are turned on to prevent the entire surge current from flowing through the bypass unit 3 into the DC link capacitor via any current path through the load 5 itself, thereby protecting the parasitic diodes of the power MOSFETs M1…M6, and of course, the MOSFETs themselves, because the on-state voltage across the bypass unit 3 is much lower than the voltage across the series connection of the MOSFET diodes. If the DC link capacitor is large enough, the resulting DC link interference is negligible.

[0046] exist Figure 6 In the diagram, the input point of rectifier 5 is denoted as 51, and the two output capacitors C DC1 and C DC2 The connection point between them is designated as 52. Therefore, the SPD 1 shown is positioned between points 51 and 52 above the MOSFET and includes a first output capacitor C as an absorption element 4. DC1 In a preferred embodiment, the second SPD 1 can be additionally positioned below the MOSFET, thus surrounding the second output capacitor C. DC2 As an absorption element 4, the safety of the rectifier, which acts as the load 5, can be further greatly improved in this way.

[0047] After the surge pulse subsides, the voltage at the bypass unit becomes negative. Once the current through bypass unit 3 also becomes negative, bypass unit 3 will turn off, which can be achieved particularly effectively by using a thyristor that will automatically turn off in bypass unit 3. Then, the diode of the MOSFET will turn on again. Furthermore, a DC link capacitor can be selected to prevent undervoltage and / or overvoltage on the DC link, and electrical equipment powered by the DC link can operate under nominal conditions, such as exceeding 100μs, 400μs, or 1000μs, without detecting any interference. For the worst case, the expected voltage deviation at the DC link during the surge event can be approximated as...

[0048] Another possibility for the hardware implementation of bypass unit 3 is to use an IGBT switch connected in parallel with a diode to implement bypass path 34 and connect the first and second terminals of bypass unit 3. In this case, the concept works exactly the same, however, fewer gate drivers are typically required.

[0049] at last, Figure 7 The description provided can be used to apply the invention to... Figure 6 The flowchart illustrates the operation steps of a multi-stage inverter. In the flowchart, state I represents normal operation. State II represents the question of whether a surge event has been detected ("y"...yes) or not ("n"...no"). If no surge event is detected, normal operation continues because there may be a pulse but not enough energy. However, if a surge event has been detected, in state III, the bypass unit is switched to conduction mode, and the MOSFETs in the multi-stage inverter are turned on. In state IV, the surge and the resulting overload condition are monitored, for example, for 200µs. If the overload condition ("n") is no longer found, in state Va, the MOSFETs resume operation and normal operation is restored. If the overload persists after 200µs, in state Vb, an error state can be activated to terminate operation and prevent damage.

Claims

1. A surge protection device (1) for suppressing power surges occurring in a power system (10) having at least a first power line (A) and a second power line (B) for supplying power, the surge protection device (1) comprising: The detection unit (2) is connected to the first power line (A) and / or the second power line (B) for generating a detection signal (d) indicating that a power surge caused by the power surge has occurred in the power system (10). The bypass unit (3) has: a first bypass terminal (31) that can be connected to a first power line (A) or a second power line (B); a second bypass terminal (32) connected to the first bypass terminal (31) via an electrical bypass path (34); and a trigger terminal (33) designed to receive the detection signal (d) generated by the surge detection unit (2), wherein the electrical bypass path (34) is capable of switching from a resistance-off state to a conduction state in response to the detection signal (d). The absorption unit (4) has a first absorption terminal (41) that can be connected to the second bypass terminal (32) of the bypass unit (3), and the absorption unit (4) is designed to suppress the surge when the bypass path (34) is in a conducting state.

2. The surge protection device (1) according to claim 1, characterized in that, To generate the detection signal (d), the detection unit (2) is configured to integrate the rate of change of voltage between the first electric line (A) and the second electric line (B) and / or the rate of change of current in the first electric line (A) and / or the second electric line (B), and preferably scale the integral of the rate of change to obtain a detection signal (d) indicating the presence of a pulse and / or the presence of energy transmitted by the pulse, and / or The feature is that the detection signal (d) adopts a first state designed to switch the electrical bypass path (34) to the on state when the detection signal (d) exceeds a predetermined threshold.

3. The surge protection device (1) according to claim 2, characterized in that, The detection unit (2) includes a capacitor or an inductor to integrate the rate of change and convert it into the detection signal (d).

4. The surge protection device (1) according to any one of the preceding claims, characterized in that, The detection unit (2) includes or is a digital measuring device, which is preferably designed to monitor the presence of an energy-rich pulse and generate the detection signal (d) based on the monitoring results.

5. The surge protection device (1) according to any one of the preceding claims, characterized in that, The electrical bypass path (34) of the bypass unit (3) includes a switching device for electrically connecting the first bypass terminal (31) and the second bypass terminal (32). The switching device is selected from the group including a triac, a silicon controlled rectifier (SCR), and a thyristor. Each element in the group has a gate electrode connected to the trigger terminal (33) of the bypass unit (3) to receive the detection signal (d).

6. The surge protection device (1) according to claim 5, characterized in that, In the bypass unit (3), an inductor (L1) is arranged between the first bypass terminal (31) and the second bypass terminal (32) and in series with the switching device to prevent overcurrent in the switching device.

7. The surge protection device (1) according to any one of the preceding claims, characterized in that, The absorption unit (4) includes absorption elements in the form of electrical impedance and / or rheostats and / or capacitors and / or resistors.

8. An apparatus (100) comprising: According to any one of claims 1 to 7, the surge protection device (1) and the electrical load (5) are used to suppress power surges in a power system (10) having at least a first power line (A) and a second power line (B) to supply power, and the electrical load (5) is designed to be powered via the first power line (A) and the second power line (B) of the power system (10).

9. The apparatus (100) according to claim 8, characterized in that, The electrical load (5) is an AC-DC converter, preferably a multi-stage active bidirectional AC-DC converter, which is designed to convert the AC power supply voltage provided by the first power line (A) and the second power line (B) into a rectified DC voltage.

10. The apparatus (100) according to any one of claims 8 or 9, characterized in that, The surge protection device (1) is an integrated component of the electrical load (5).

11. The apparatus (100) according to any one of claims 8 to 10, characterized in that, The load (5) includes internal elements that can be used as absorption elements, preferably: a DC bus capacitor on the output side of a multi-stage bidirectional AC-DC converter for outputting the rectified DC voltage; or a resistor or capacitor in the load (5); and The feature is that the internal element is used as an absorption element in the absorption unit (4) to suppress the surge.

12. The apparatus (100) according to claim 11, characterized in that, The electrical bypass path (34) of the bypass unit (3) runs in parallel with at least a portion of the electrical load (5) that requires surge protection, preferably in parallel with the semiconductor switch of the multi-stage bidirectional AC-DC converter that serves as the load (5) from the first bypass terminal (31) to the DC bus capacitor.

13. A surge protection method for suppressing power surges occurring in a power system (10), the power system (10) having at least a first power line (A) and a second power line (B) for supplying power, the method comprising the steps of: A detection signal (d) is generated by means of a detection unit (2), the detection signal (d) indicating that an energy-rich pulse caused by the power surge has occurred in the power system; A bypass unit (3) is provided, the bypass unit (3) having: a first bypass terminal (31) connected to a first power line (A) or a second power line (B); a second bypass terminal (32) connected to the first bypass terminal (31) via an electrical bypass path (34); and a trigger terminal (33) designed to receive the detection signal (d) generated by the surge detection unit (2); In response to the detection signal (d), the electrical bypass path (34) is switched from the resistance disconnected state to the electrical conduction state; By means of the absorption unit (4) connected to the second bypass terminal (32) of the bypass unit (3), the surge is prevented when the bypass unit (3) is in the conducting state.

14. The method according to claim 13, characterized in that, An active multi-stage bidirectional AC-DC converter is provided for an electrical load (5) powered by the power system (10).

15. The method according to claim 14, characterized in that, In the event of a surge, the multi-stage bidirectional AC-DC converter is deactivated and reactivated after the surge event.

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