阅读说明：本技术 用于组合地保护负载以防暂时和瞬态过电压的电路布置结构 (Circuit arrangement for combined protection of loads against temporary and transient overvoltages ) 是由 F·朔尔克 R·布罗克 于 2018-10-17 设计创作，主要内容包括：本发明涉及一种用于组合地保护负载以防暂时和瞬态过电压的电路布置结构,具有在存在暂时过电压的情况下负载的紧急运行和集成的续流限制,其中,在电源侧的输入端子之间设有第一过电压放电器、尤其是火花放电装置或压敏电阻,以及在负载侧的输出端子之间设有第二过电压放电器、尤其是压敏电阻,以用于续流限制。按照本发明在输入和输出端子之间的纵向支路中以及在输出侧的横向支路中分别设有至少一个受控的半导体开关,其中,在纵向支路中的半导体开关并联连接有机械开关以及纵向电容。此外,在横向支路中的半导体开关是串联电路的组成部分,所述串联电路包括由第二过电压放电器和横向电容组成的并联电路。在纵向支路中在输入端子与由纵向电容、受控的半导体开关和机械开关组成的并联电路之间设有串联电感。此外存在用于操控所述半导体开关的微控制器,所述微控制器与在纵向支路中的电流检测器相连接。(The invention relates to a circuit arrangement for combined protection of loads against transient and transient overvoltages, having emergency operation of the load in the presence of transient overvoltages and integrated freewheel limitation, wherein a first overvoltage arrester, in particular a spark arrester or varistor, is arranged between input terminals on the mains side and a second overvoltage arrester, in particular a varistor, is arranged between output terminals on the load side for freewheel limitation. According to the invention, at least one controlled semiconductor switch is provided in each case in a longitudinal branch between the input and output terminals and in a transverse branch on the output side, the semiconductor switches in the longitudinal branch being connected in parallel to a mechanical switch and to a longitudinal capacitor. The semiconductor switches in the transverse branch are furthermore part of a series circuit which comprises a parallel circuit of the second surge arrester and the transverse capacitor. A series inductance is provided in the longitudinal branch between the input terminal and a parallel circuit of a longitudinal capacitance, a controlled semiconductor switch and a mechanical switch. Furthermore, a microcontroller for actuating the semiconductor switches is present, which is connected to the current detector in the longitudinal branch.)

1. Circuit arrangement for combined protection of a load against transient and transient overvoltages with emergency operation of the load in the event of a transient overvoltage and integrated freewheel limitation, wherein a first overvoltage arrester (1), in particular a spark arrester or varistor, is arranged between input terminals (E) on the mains side and a second overvoltage arrester (2), in particular a varistor, is arranged between output terminals (A) on the load side for freewheel limitation,

it is characterized in that the preparation method is characterized in that,

at least one controlled semiconductor switch is arranged in each of a longitudinal branch between the input and output terminals (E; A) and a transverse branch on the output side, the semiconductor switches in the longitudinal branchA mechanical switch (S) and a longitudinal capacitor are connected in parallelIn addition, a semiconductor switch (HL) in the lateral branch_Quer) Is part of a series circuit, the series circuit includingComprising a second surge arrester (2) and a transverse capacitor (C)_Quer) A parallel circuit comprising a longitudinal branch having an input terminal (E) and a longitudinal capacitorControlled semiconductor switchAnd a series inductance (L) between the parallel circuits of the mechanical switch (S), and a microcontroller (μ C) for actuating the semiconductor switch, which microcontroller (μ C) is connected to the current detector (SD) in the longitudinal branch.

2. The circuit arrangement according to claim 1,

the microcontroller (μ C) is connected to the input terminals (E) in order to detect overvoltages in order to receive corresponding input voltage values.

3. Circuit arrangement according to claim 1 or 2,

means for detecting zero crossings are provided, on the basis of which the semiconductor switches can be switched on in phase.

4. Circuit arrangement according to one of the preceding claims,

actuation of the semiconductor switches in the longitudinal branches by means of pulse transformers

5. Circuit arrangement according to one of the preceding claims,

in the event of a Temporary Overvoltage (TOV) being detected, the semiconductor switch (HL) in the lateral branch is actively switched by means of a pulse transformer_Quer) And passively by means of a TOV diode in the event of an overvoltage transient, wherein the passive control is given by a voltage above the TVS diode voltage.

6. Circuit arrangement according to one of the preceding claims,

the microcontroller (μ C) is connected to the output terminal (A) for detecting an output voltage in order to provide a logic signal corresponding to the respective load situation.

7. Circuit arrangement according to one of the preceding claims,

avoiding semiconductor switches in the longitudinal branches based on the value determined by the current detector (SD)The mechanical switch (S) is turned on.

8. Circuit arrangement according to one of the preceding claims, characterized in that the longitudinal and transverse capacitancesA capacitive voltage divider is formed in order to be able to continue the operation of a small load connected to the output terminal (A) even in the event of a Temporary Overvoltage (TOV).

Technical Field

The invention is based on a circuit arrangement for combined protection of loads against transient and transient overvoltages with emergency operation of the load in the presence of transient overvoltages and integrated freewheel limitation, wherein according to claim 1 a first overvoltage arrester, in particular a spark arrester or varistor, is provided between the input terminals on the mains side and a second overvoltage arrester, in particular a varistor, is provided between the output terminals on the load side for freewheel limitation.

Background

As is known, overvoltage protectors contribute significantly to the functional maintenance of electrical and electronic equipment.

The use of overvoltage protectors to protect electrical equipment has been a standard.

Since the overvoltage at the source of the atmosphere (i.e. the lightning overvoltage) occurs in principle with respect to the ground potential of the electrical system, an overvoltage protection of the low-voltage electrical system must be provided between the active conductor and the local ground potential. The number of protection paths and the arrester connections required are designed according to the respective network system of the low-voltage consumer system. A standard arrester therefore has the task of limiting the rapid and short-term overvoltage. Since the formation of said overvoltages is also referred to as lightning and switching overvoltages, said overvoltages belong to the term "transient overvoltages". While a time-limited voltage rise with the supply frequency is referred to as a temporary overvoltage or TOV. Such temporary overvoltages can only be limited to a limited extent by the overvoltage protection device due to their relatively long duration and, in particular, impose very high requirements on the arrester. The cause of TOV may be the most diverse fault conditions within and outside the low voltage power supply.

Disclosure of Invention

In view of the above, it is therefore an object of the present invention to provide a circuit arrangement for combined protection of a load against transient and transient overvoltages, which circuit arrangement furthermore enables emergency operation of the load even in the presence of transient overvoltages.

The object of the invention is achieved by a circuit arrangement according to the features of claim 1 in combination, wherein the dependent claims at least form specific embodiments and further developments.

The circuit arrangement for combined protection of loads against transient and transient overvoltages is therefore based on an emergency operation of the load together with a circuit arrangement based on semiconductor-based controlled longitudinal and transverse elements. The capacitors used in the longitudinal and transverse branches provide the possibility of ensuring emergency operation at constant power, which allows, for example, the operation of the power supply of safety-relevant controllers in the event of temporary overvoltages. Instead of using capacitors as longitudinal and transverse elements, there is in principle the possibility of using ohmic or inductive voltage dividers. The principle according to the invention based on controlled longitudinal and transverse impedances thus remains unaffected.

According to the invention, in a first embodiment of the invention, controlled semiconductor switches are used in the longitudinal branch between the input and output terminals. The other controlled semiconductor switch is in the lateral branch of the output side.

In a preferred embodiment, the semiconductor switches in the longitudinal branches have mechanical switches (for example, in the form of relays) connected in parallel and longitudinal capacitors connected in parallel.

The semiconductor switches in the lateral branch are part of a series circuit. The series circuit comprises a parallel circuit of a second surge arrester (in particular a varistor) and a transverse capacitor.

In order to compensate for the inertia of the mechanical switch and to ensure protection of the semiconductor switch in the longitudinal branch, a series inductance is provided in the longitudinal branch between the input terminal and a parallel circuit composed of the longitudinal capacitance, the controlled semiconductor switch and the mechanical switch.

A microcontroller undertakes the actuation of the semiconductor switch, wherein the microcontroller is connected to the current detector in the longitudinal branch.

In a further embodiment of the invention, the microcontroller is connected to the input terminals for detecting overvoltages, so that the respective input voltage value can be determined and used for processing and for obtaining the logic signal.

In a further development, provision is made for a zero crossing detection device, on the basis of which the respective semiconductor switch can be switched on in phase.

The control currents for the semiconductor switches in the longitudinal branches are preferably separated, in particular by means of a pulse transformer.

In the event of a detection of a temporary overvoltage, the semiconductor switches in the lateral branch are actively controlled by means of a pulse transformer. In the event of an overvoltage transient, the actuation of the semiconductor switches in the lateral branch takes place via TVS diodes, wherein the passive actuation is given by a voltage greater than the TVS diode voltage.

In a further embodiment of the invention, the microcontroller provides logic signals for detecting the connection of the output voltage to the output terminals in order to correspond to the respective load situation.

The mechanical switch already mentioned is switched on, based on the value determined by the current detector, in order to avoid overloading of the semiconductor switch in the longitudinal branch.

The longitudinal and transverse capacitances form a capacitive voltage divider in order to be able to continue the operation of the small load connected to the output terminals even in the event of temporary overvoltages.

If the mechanical switch is omitted, the advantage results that the slow response time of the mechanical switch has no negative effect on the circuit arrangement. In this case, the longitudinal inductance mentioned for decoupling can be eliminated. The maximum voltage value at the load can be set by the switching level of the semiconductor switches in the longitudinal branches.

In order to limit the power loss of the semiconductor switches in the longitudinal branches in the case of large currents due to the load, a parallel connection of a plurality of longitudinal semiconductors must be carried out.

Drawings

The invention is explained in more detail below with the aid of examples and figures.

Detailed Description

The diagram shows a schematic circuit diagram of an arrangement according to the invention for combined protection of a load against transient and transient overvoltages, with the possibility of emergency operation of the load in the presence of transient overvoltages together with integrated free-wheeling limitation.

As shown in the figure, a first surge arrester, which is known per se and is in particular designed as a spark-over device or as a varistor, is present between the input terminals E. The first surge arrester, which is located approximately upstream, absorbs a large part of the occurring surge currents and is designed to achieve the maximum expected TOV voltage. While surge currents of smaller magnitude are switched by the semiconductor switches HL in the transverse branches_QuerAbsorption, and more precisely semiconductor switches in the longitudinal branchAnd (6) turning off.

Between the input and output terminals there is a longitudinal inductance L in the longitudinal branch and a parallel circuit comprising a longitudinal capacitanceMechanical switch S and the already mentioned semiconductor switch in the form of, for example, two parallel-connected semiconductorsA combination of mechanical switches, MOSFETs and IGBTs is particularly advantageous here because of the low power losses.

The lateral branch at the output terminal, which can be seen in the figure, comprises a semiconductor switch HL_QuerAnd as a constituent of the series circuit has a second surge arrester and a transverse capacitor C_QuerThe second surge arrester is designed as a varistor 2 for freewheeling limitation.

Microcontroller μ C for actuating semiconductor switches in a longitudinal branchAnd semiconductor switches HL in the lateral branches_Quer。

Furthermore, a current detector SD is present, which leads to a corresponding input of the microcontroller.

Furthermore, the microcontroller has inputs for input voltage detection and output voltage detection.

The current detector SD can be used to switch on the mechanical switch S in a continuously operating manner in order to relieve the semiconductor switch when it is detected that the load current exceeds a certain setpoint valueThe load of (2).

In order to be able to achieve a correct phase switching, the invention provides for zero crossing detection. The zero crossing detection prevents excessively high inrush currents which could otherwise damage the semiconductor switches used or reduce the service life of the semiconductor switches.

The voltage detection at the input can be implemented as follows: first of all, identifyThe temporary voltage, but also the transient voltage, is detected and can be reacted to by using the microcontroller and its internal program. For vertical semiconductorIs preferably performed by means of a pulse transformer arrangement, wherein the switching time and the energy conversion can be reduced.

For semiconductor switches HL in the lateral branch_QuerIs actively operated by means of a pulse transformer in the event of a temporary overvoltage. And passively by using TVS diodes in case of transient overvoltage. When the actuation by the pulse transformer is deactivated and the voltage is greater than the TVS diode voltage, the passive actuation in the lateral branch is always activated. This is the case in the event of a transient overvoltage and at the beginning of a transient overvoltage (for example when switching on a transient overvoltage to a circuit arrangement until the transient overvoltage is detected by the microcontroller).

The detection of transient overvoltage events is in principle carried out by means of a microcontroller, which however has a reaction time which is hardly influenced. In this case, a very large current may flow through the semiconductor switch in the longitudinal direction.

By passive TOV voltage detection by means of a diode chain (for input voltage detection), the semiconductor switches in the longitudinal branches can be controlled approximately while bypassing the microcontrollerDirect manipulation is performed. By more quickly identifying and switching off semiconductor switches in the longitudinal branchesCan carry significantly higher inrush current loads.

Since mechanical switches based on relays also have a limited reaction time, for example between 2 and 8ms, a solution must be proposed in order to react quickly to transient overvoltage events. In particular, a series inductance L of, for example, 20 μ H is used. The decoupling inductance limits the relay current, thereby avoiding damage and relieving the load of the lateral semiconductors.

By using the capacitor according to the embodiment, emergency operation at constant power can be ensured. In for exampleAt this time, the 150W load can be operated at the output even if shutdown (i.e., grid disconnect) is performed due to the TOV.

In the case of temporary overvoltages due to zero line losses, the load conditions in the individual phases should be taken into account.

The circuit arrangement according to the exemplary embodiments can also be implemented in particular in three or more phases. For efficient transient overvoltage protection, longitudinal switching is soughtIs less than 500 ns.

The operation of the described arrangement shall be briefly outlined below.

At e.g. a load<6A and voltage U_TOV>In the continuous operation at 340V, usually only the semiconductor switches in the longitudinal branch are active in order to be able to react quickly to a possible neutral disconnection.

Under load>6A and U_TOV>In case of 340V, the semiconductor switchAnd the mechanical switch S, in order to reduce the power loss during continuous operation. The switching dynamics of the mechanical switch S may be considered sufficient for load protection at around 340V. Only when the voltage crosses zero is switched on. The mechanical switch S can be switched by parallel semiconductor switchesThe current-free implementation increases the service life of the switch.

When transient state occursAt voltage, the surge arrester 1 located upstream absorbs a large part of the surge current. Semiconductor switch HL with smaller amplitude surge current in transverse path_QuerAbsorption until a shutdown in the longitudinal branch takes place. The following two cases should be distinguished here.

In the first case, only the semiconductor switches in the longitudinal path are active. The longitudinal elements can be closed quickly, i.e. the surge arrester 1 absorbs the entire surge current.

In the second case, the semiconductor switch and the mechanical switch in the longitudinal branch are active. The mechanical switch is too slow to react to a transient event. In this case, the inductive decoupling mentioned is necessary, which reduces the surge current in the semiconductor to a loadable extent.

During operation of the TOV, a zero line open may occur. Here U is_TOV<270V and load>12A. The semiconductor switches and the mechanical switches in the longitudinal branches remain active, i.e. the load can continue to operate normally.

At U_TOV>270V and I_Last<12A, the longitudinal switches in the transverse path are deactivated in the event of a fault. By means of capacitive voltage dividersAnd C_QuerThe load is continued to run up to, for example, 150W, so that the desired emergency running characteristic occurs to improve the running safety.

The current threshold values mentioned, for example, >12A, constitute the regulating device with which the transverse and longitudinal switches can be controlled. But alternatively only a voltage magnitude of substantially 270V may be adjusted without load current.

In the case of a short circuit L-N in the adjacent phase, in I_Last<6A, only the semiconductor switch is active and can thereby react quickly to a fault situation.

At loads >6A, the semiconductor switches and the mechanical switches in the longitudinal branches are active. The reaction time is predetermined by a mechanical switch. The voltage rises to 1.33 times the reference voltage, for example for about 2 ms. This short-term voltage rise represents a transient load of a height of up to 1.33 × the reference voltage for the load and can be regarded as no problem. The mechanical switch is switched off currentless, since the semiconductor switches in the longitudinal branches absorb the entire current.

In the event of a short circuit L-N in the phase of the circuit arrangement itself, the semiconductor switch and the mechanical switch are jointly activated until the fault is eliminated by the upstream-located safety device.

In the case of a combination of semiconductor switches and mechanical switches in the longitudinal branch, the maximum voltage value at the load is 1.33 × U in the event of a temporary event_Ref. In the event of a transient, the protection level on the load is regulated to about 650V.