CN115938835A - Dual-power switch arc extinguishing circuit based on power electronic technology - Google Patents

Abstract

The invention relates to a dual-power switch arc extinguishing circuit based on power electronics technology, and its technical characteristics are: including a power electronics module, a load RL1, a diode D1, a diode D2, a capacitor C, a current limiting resistor R1, and a terminal B of a circuit breaker DL1 It is connected to one end of the load RL1, the A end of the circuit breaker DL1 is connected to the current limiting resistor R1, and the other end of the current limiting resistor R1 is connected in series with the capacitor C1 to the B end of the circuit breaker DL1; the power electronic module is connected in parallel to the circuit breaker Between the A terminal and the B terminal of DL1; the two control terminals of the power electronic module are respectively connected between the current limiting resistor R1 and the capacitor C1 and between the capacitor C1 and the load RL1. The invention is mainly applied to circuit breakers with dual power switches. The electric arc generated when the circuit breaker switch is turned off can be transferred through the power electronic module to realize the function of "zero arc". It has the characteristics of short conduction time and low cost, and reduces double The breaking voltage of the power switch can effectively improve the service life of the dual power switch.

Description

A dual power switch arc extinguishing circuit based on power electronics technology

technical field

The invention belongs to the technical field of power electronics, and relates to switching arc equipment of power electronics, in particular to a dual power supply switch arc extinguishing circuit based on power electronics technology.

Background technique

The dual power switch (circuit breaker) plays a crucial role of turning on and breaking in the low-voltage power system. When the circuit breaker at one end of the dual power switch is disconnected, if the circuit voltage is less than 10-20V, or the current is greater than 80-100mA, an arc will be generated between the switch contacts. The arc current during switch arcing is not easy to extinguish. If it is not controlled, it will damage the switch contacts, affect the service life, and generate huge heat, which poses a serious threat to the safety of other electrical equipment around. At the same time, the circuit breaker switch needs a certain insulation recovery time after the arc is broken, which prolongs the time for disconnecting the circuit, and it is difficult to meet the requirements of the quick action of the dual power switch.

Traditional mechanical switches usually use the methods of controlling the degree of ionization and deionization of the arc gap medium, controlling the temperature of the arc gap, and increasing the voltage between the arc gaps to extinguish the arc. Using a specific arc gap medium, increasing the distance of the arc gap, changing the path of the arc column, and improving the breaking capacity Speed, increase the distance between contacts and other methods. However, the traditional mechanical and physical arc extinguishing methods not only have strict technical requirements for the structural design of the mechanical switch, but also have long arc interruption time (milliseconds), short electrical life (several to thousands of times), Disadvantages of large size and low cost performance. The electronic arc extinguishing method using resonance to create a current zero point not only has strict requirements on the mechanical switch itself, but also needs to adjust the resonance parameters according to the actual application conditions of the mechanical switch, which limits the universality of the application. Therefore, problems and failures caused by arcing have to be faced in selecting and designing switching applications.

The root of the difficulty in eliminating arcs is that the inductive load current cannot change abruptly. The arc current generated after the circuit breaker contacts are segmented must have a natural zero-crossing process, which greatly delays the time for the circuit breaker to truly achieve electrical isolation. Especially in the case of double power cut-off switch, when the arc of the primary power supply cannot be extinguished, it cannot be connected to the standby power supply for use, resulting in the switching of dual power switches, the switching process alone is as high as tens of milliseconds, which cannot be avoided The power outage on the load side violates the original design intention of the dual power switch.

To sum up, how to quickly deal with the arc during the breaking process of the switch to realize the low-voltage non-stop operation of the dual power supply circuit and the zero power outage during maintenance and construction is an urgent problem to be solved at present.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a dual-power switch arc extinguishing circuit based on power electronics technology, which can handle the arc during the switch breaking process, so that it can be extinguished as soon as possible without natural zero crossing, and at the same time, energy absorption is designed The branch circuit limits the voltage to a safe level, so as to realize the low-voltage non-blackout operation of the dual power supply circuit and zero blackout during maintenance and construction.

The present invention solves its technical problem and realizes by taking the following technical solutions:

A dual-power switch arc extinguishing circuit based on power electronics technology, connected to a circuit breaker DL1, including a power electronics module, a load RL1, a diode D1, a diode D2, a capacitor C and a current limiting resistor R1, the B of the circuit breaker DL1 connected to one end of the load RL1, the A terminal of the circuit breaker DL1 is connected to the current limiting resistor R1, and the other end of the current limiting resistor R1 is connected in series with the capacitor C1 to the B terminal of the circuit breaker DL1; the power electronic module is connected in parallel Between the A terminal and the B terminal of the circuit breaker DL1; the two control terminals of the power electronic module are respectively connected between the current limiting resistor R1 and the capacitor C1 and between the capacitor C1 and the load RL1.

Further, the power electronic module is composed of a power electronic device Q1 and a power electronic device Q2 in anti-series connection, and the power electronic device Q1 and the power electronic device Q2 are both semi-controlled power electronic devices.

Further, the power electronic device Q1 and the power electronic device Q2 have their own diodes, or the power electronic device Q1 and the power electronic device Q2 are respectively connected in parallel with a diode D1 and a diode D2; the power electronic device Q1 and the diode D2 and the power electronic device Q2 and Diodes D1 are all in anti-series relationship.

Further, the power electronic module is composed of a power electronic device Q1 and a power electronic device Q2 connected in antiparallel, and the power electronic device Q1 and the power electronic device Q2 are all fully-controlled power electronic devices.

Further, the power electronic device Q1 and the power electronic device Q2 are IGBTs, NPN transistors or N-channel field effect transistors.

Further, a high voltage surge arrester group MOV is connected in parallel between the A terminal and the B terminal of the circuit breaker DL1, and the high voltage surge arrester group MOV forms an energy absorbing branch.

Further, a delay circuit is also connected to the power electronic module.

Advantage and positive effect of the present invention are:

1. According to the arc characteristics generated by the circuit breaker switch, the present invention connects the power electronic device based on electronic arc extinguishing technology in parallel with the circuit breaker switch, shunts the current on the switch during the switch breaking process, and limits the voltage at both ends of the switch to several volts The lower level, thus preventing the strong electric field emission and thermal electron emission necessary to generate the arc, transfers the current to the pre-set commutation branch, so that the mechanical contact of the circuit breaker is broken under the condition of no arc, And the final fault current breaking is completed by the transfer branch, so that the arc of the primary side power supply is extinguished, and the backup side power supply is connected, thereby shortening the switching time of the low-voltage AC dual power supply system and realizing the function of power distribution network without power failure.

2. The present invention is independent of the switch itself, and can be used in conjunction with existing switches. The circuit has a large overload capacity, low temperature rise, and is easy to use. In the process of breaking the switch, the arc current on the switch is shunted, and the voltage at both ends of the switch is limited to a low level of several volts, which realizes the function of "zero arc" in the switching process of the dual power switch. The present invention is different from the air arc extinguishing grid used in conventional low-voltage switches, which improves the fire protection level, and does not need to wait for the arc to appear before going to the arc extinguishing treatment, but prevents the arc from appearing in the whole process. The use of power electronics technology greatly shortens the switching transition time (≤10ms), and it is basically lossless compared to other arc extinguishing methods. It is a typical green product.

Description of drawings

Fig. 1 is the circuit diagram of embodiment 1 of the present invention;

Fig. 2 is the circuit diagram of embodiment 2 of the present invention;

Fig. 3 is a delay circuit diagram of the present invention;

Fig. 4 is the load side electric current waveform figure of the present invention;

Fig. 5 is an equivalent schematic diagram of the breaking process in the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The design concept of the present invention is: the present invention proposes an arc-extinguishing circuit for a dual-power switch based on power electronics technology. The arc-extinguishing circuit is independent of the switch itself and can be used in conjunction with existing switches. It connects the power electronic device and the switch in parallel, so that the voltage across the switch is limited to a low level of a few volts, thereby preventing the establishment of strong electric field emission and thermal electron emission necessary for arc generation. The arc current transfer branch is designed, and the current transfer principle is used to introduce the generated arc current into the transfer branch, so as to shorten the switching time of the dual power switch and ensure the load side without power failure. The energy-absorbing branch is designed to conduct and release energy after the circuit breaker is turned off, so as to avoid the induced electromotive force generated by the inductive element in the DC circuit due to the sudden change of current from breaking down the power electronic switch on the commutation branch.

Example 1

A dual power switch arc extinguishing circuit based on power electronics technology, as shown in Figure 1, the arc extinguishing circuit is connected to the circuit breaker DL1, including power electronic devices Q1, power electronic devices Q2, load RL1, diode D1, diode D2 , capacitor C and current limiting resistor R1.

The circuit breaker DL1 includes an A terminal (power input terminal) and a B terminal, the B terminal of the circuit breaker DL1 is connected to one end of the load RL1, the A terminal of the circuit breaker DL1 is connected to the current limiting resistor R1, and the other terminal of the current limiting resistor R1 One end is connected in series with the capacitor C1 to the B end of the circuit breaker DL1. The power electronic device Q1 and the power electronic device Q2 are all semi-controlled power electronic devices, and the power electronic device Q1 and the power electronic device Q2 are connected in reverse series to form the power electronic module in the virtual frame of Figure 1, and the power electronic module constitutes the current transfer branch. The power electronic module is connected in parallel between the A terminal and the B terminal of the circuit breaker DL1. The control terminal of the power electronic device Q1 is connected between the current limiting resistor R1 and the capacitor C1, and the control terminal of the power electronic device Q2 is connected between the capacitor C1 and the load RL1.

The power electronic devices Q1 and Q2 may be IGBTs, NPN transistors or N-channel field effect transistors. In this embodiment, the power electronic devices Q1 and Q2 use IGBTs.

The power electronic device Q1 and the power electronic device Q2 may have their own diodes D1 and D2, or separate external diodes D1 and D2 in parallel, the power electronic device Q1 and the diode D2, or the power electronic device Q2 and the diode D1 are in an anti-series relationship .

In Figure 1, the A terminal of the circuit breaker DL1 is connected to the collector (C) of the power electronic device Q1 and the negative terminal of the diode D1, the emitter (E) of the power electronic device Q1, the positive terminal of the diode D1, and the power electronic device The emitter (E) of Q2 is connected to the positive terminal of diode D2. Terminal B of the circuit breaker DL1 is connected to the collector (C) of the semi-controlled power electronic device Q2 and the negative terminal of the diode D2. At this time, the power electronic device Q1 is connected to the positive terminal of the diode D1, and then connected to the half-controlled power electronic device Q2 and the positive terminal of the diode D2. That is to say, Q1 and Q2 are connected in series between the contacts at both ends of the circuit breaker DL1, and diodes D1 and D2 are respectively connected in parallel to Q1 and Q2.

In the above circuit, the current limiting resistor R1 and the capacitor C1 form a charging unit, and the capacitor C1 is connected to the A terminal (power input terminal) of the circuit breaker DL1 through the current limiting resistor R1.

In the present invention, the power electronic module is connected in parallel between the circuit breakers DL1 to ensure that the bidirectional current has a path on the parallel branch of the circuit breaker DL, which can realize "zero arc" and does not need to go through the process of natural zero-crossing of the arc current, ensuring that the load Side without power.

The working process of this embodiment is:

When the system is running normally, the circuit breaker switch DL1 is closed and energized, and the current flows through the main circuit. The power supply charges the capacitor C through the current limiting resistor R1.

When the circuit breaks down, when the circuit breaker switch DL1 is disconnected, when the potential difference between the capacitor C1 terminal and the load RL1 is greater than the turn-on voltage of the power electronic device Q1 or Q2 (the potential difference is approximately equal to the potential at both ends of the circuit breaker switch difference), the semi-controlled power electronic device Q1 or Q2 triggers conduction. The capacitor C1 forms a loop through the collector and emitter of the semi-controlled power electronic device Q1 or Q2, and the arc current is transferred to the power electronic module branch. The electric field strength between the contacts of the circuit breaker switch DL1 drops rapidly, so as to complete the rapid arc extinguishing of the circuit breaker switch DL1.

The capacitor C1 discharges the load RL through the semi-controlled power electronic device Q1 or Q2, the current is consumed in the power electronic module, and the power electronic device Q1 and Q2 are turned off.

At this time, the arc between the contacts of the power circuit breaker on the primary side of the dual power switch is extinguished, and the other power supply is automatically switched, and the standby power supply is put into use.

In this embodiment, during the arc treatment process, only current flows through the power electronic module, and no arc is generated between the contacts. The input terminal and output terminal of the power electronic module are not insulated and isolated, and the charging power supply of the capacitor is provided by the current limiting of the main circuit power supply of the circuit breaker switch. The anti-series power electronic device Q1 and power electronic device Q2 ensure that there is a path for bidirectional current. During the breaking process of the circuit breaker switch, the base of the power electronic device does not need a series resistor to limit the current, which reduces the loss of the capacitive charge before the power electronic device is turned on, and improves the trigger speed of the power electronic device. At the same time, the resistance is used to limit the current when the capacitor is charged, so as to reduce the current impact when the circuit breaker switch is closed. The capacitor is connected to the circuit breaker switch and the load, and is charged by the main circuit power supply, which does not affect the insulation withstand voltage at both ends of the switch, and there is no leakage current when the circuit breaker switch is turned off.

In actual use, when the requirements for arc extinguishing speed are not high, a delay circuit can be used on the power electronic device in the power electronic module. The delay circuit is shown in Figure 3, including resistor R2, resistor R3, and capacitor CL1 , the resistor R2 and the capacitor CL1 are connected in series between the collector and the emitter of Q1, one end of the resistor R3 is connected to the gate of Q1, and the other end is connected between the resistor R2 and the capacitor CL1. The delay circuit can ensure that the circuit breaker switch maintains a sufficient distance after the switch is turned off, so as to prevent the arc from re-igniting after the arc is extinguished.

Example 2

A switching arc treatment device based on power electronics, as shown in Figure 2, includes a circuit breaker DL1, power electronic device Q1, power electronic device Q2, load RL1, capacitor C, current limiting resistor R1 and high voltage arrester group MOV.

The main difference between the second embodiment and the first embodiment is that the power electronic devices Q1 and Q2 in this embodiment are full-control power electronic devices, and the power electronic devices Q1 and Q2 are in an anti-parallel relationship.

The specific connection relationship of the circuit is as follows: the circuit breaker DL1 includes an A terminal (power input terminal) and a B terminal, the B terminal of the circuit breaker DL1 is connected to one end of the load RL1, and the A terminal of the circuit breaker DL1 is connected to the current limiting resistor R1. The other end of the current limiting resistor R1 is connected in series with the capacitor C1 to the B end of the circuit breaker DL1. The power electronic device Q1 and the power electronic device Q2 are all fully-controlled power electronic devices, and the power electronic device Q1 and the power electronic device Q2 are connected in antiparallel together to form the power electronic module in the virtual frame of Figure 2, and the power electronic module constitutes the current transfer branch. The power electronic module is connected in parallel between the A terminal and the B terminal of the circuit breaker DL1. The control terminal (G) of the power electronic device Q2 is connected between the current limiting resistor R1 and the capacitor C1, and the control terminal (G) of the power electronic device Q1 is connected between the capacitor C1 and the load RL1.

The two ends of the high-voltage arrester group MOV are respectively connected to the A and B pins of the circuit breaker DL1 to form an energy-absorbing branch. The high-voltage arrester group can use varistors or metal oxide arresters, which are broken down before power electronic devices in a manner similar to automatic "lightning induction", so as to achieve the purpose of protection. After the energy discharge is completed, it will automatically restore to fully insulated high-resistance state. The two ends of the high-voltage arrester group MOV are respectively connected to the A and B pins of the circuit breaker DL1 to form an energy-absorbing branch.

It should be noted that the energy-absorbing branch formed by the high-voltage arrester group MOV can also be used in the arc-extinguishing circuit of the first embodiment.

The working process of this embodiment is:

The principle of arc ignition and arc extinguishing in this embodiment is similar to that in Solution 1, the difference is that this embodiment uses fully-controlled power electronic devices Q1 and Q2 without built-in diodes, and the power electronic devices Q1 and Q2 can be controlled to turn off. The two ends of the MOV of the high-voltage arrester group are respectively connected to the A and B pins of the circuit breaker DL1, forming an energy-absorbing branch.

When the system is running normally, the circuit breaker switch DL1 is closed and energized, and the current flows through the main circuit. The power supply charges the capacitor C through the current limiting resistor R1.

When the circuit breaks down and the circuit breaker switch DL1 is disconnected, when the potential difference between the capacitor C1 terminal and the load RL1 is greater than the turn-on voltage of the power electronic device Q1 or Q2 (the potential difference is approximately equal to the potential difference between the two ends of the circuit breaker switch ), the fully-controlled power electronic device Q1 or Q2 triggers conduction. The capacitor C1 forms a loop through the collector and emitter of the fully-controlled power electronic device Q1 or Q2, and the arc current is transferred to the power electronic module branch. The electric field strength between the contacts of the circuit breaker switch DL1 drops rapidly, so as to complete the rapid arc extinguishing of the circuit breaker switch DL1.

At this time, the arc between the contacts of the power circuit breaker on the primary side of the dual power switch is extinguished, and the other power supply is automatically switched, and the standby power supply is put into use.

This embodiment is suitable for use in circuits with inductive loads. Due to the presence of inductive loads in the circuit, the inductive current cannot change suddenly. The lightning arrester MOV is connected to the circuit to prevent the induced electromotive force generated by the inductive current from being too large, resulting in breakdown of power electronic devices. After the power electronic device is turned off, the fault current is transferred to the MOV energy-absorbing branch of the arrester, and the MOV of the arrester starts to absorb energy until the fault current drops to zero, completing the breaking process of the entire fault current. During the entire arc extinguishing control process, the trend of current and voltage changes in each part of the system and circuit breaker is shown in Figure 5.

In this embodiment, the fully-controlled power electronic devices can be driven separately by using different driving voltages. Preferably, a control unit with a built-in programmable controller can be used. It can sample the voltage signal of the capacitor and the voltage signal of the connection end of the circuit breaker switch and the load, and adaptively select the appropriate control breaking method. Using the control unit can adjust the control mode according to the voltage change, which is beneficial to simplify the circuit, improve the arc extinguishing effect, and effectively improve the life of the dual power switch.

It can be seen from the above two embodiments that the present invention is mainly applied to a circuit breaker with dual power switches. By setting up power electronic devices to form a circuit, the arc generated when the circuit breaker switch is turned off is transferred to realize the idea of "zero arc". Using the power electronic module, the circuit is relatively simple, and a large potential difference is formed between the capacitor and the load after the switch is turned off to realize the conduction of the power electronic device. Utilizing the advantages of large overload capacity, short conduction time and low cost of power electronic devices, the problem of arc extinguishing in the use of 0.4kV dual power mutual investment switches is solved. The power electronic module connected in parallel reduces the breaking voltage of the dual power switch and can effectively improve the service life of the dual power switch.

The arc extinguishing circuit for dual power switches based on power electronic technology of the present invention can also be connected with a control unit, the control unit is a programmable device, which is connected with the power electronic device Q1, and the power electronic device Q1 accepts the instructions issued by the control unit and Data, and transmit the external information status of the circuit (such as circuit breaker switch status, load status, etc.), so as to realize the intelligent control function.

The working principle of the present invention is: after the required arc extinguishing circuit breaker switch DL1 is closed, the power supply rapidly charges the capacitor C1 through the current limiting resistor R1. When the circuit breaker switch is turned off, an arc current is generated between the contacts, and when the circuit breaker switch is turned off, the potential difference between the circuit breaker switch DL1 and the capacitor C1 is greater than the turn-on voltage of the power electronic module, and the electric power module The semiconductor device is triggered to conduct, the arc is transferred to the branch circuit of the power electronic module, the current at both ends of the circuit breaker switch quickly drops to 0, and the capacitor C1 quickly discharges the load RL1 through the power electronic device Q1 or Q2. The electric field strength between the contacts of circuit breaker DL1 drops rapidly; after the switching conditions are met, the dual power switch switches from the primary power supply to the backup power supply; the power electronic device Q1 or Q2 triggers shutdown; the current on Q1 or Q2 is cut off. So as to achieve the purpose of breaking the circuit breaker switch DL1 without arc.

The arc waveform diagrams obtained by the present invention are shown in Figure 4(a) and (b), wherein the lower picture is a partially enlarged waveform of the upper picture, and the pink one is the load side current. It can be clearly seen from the figure that the first half of the waveform is the arc generated at the moment of contact opening. Through the intervention of the arc processing circuit, the arc between the contacts is drawn out, so the second half of the waveform tends to zero, and the entire process eliminates the arc. It appears that the power electronic topology circuit is used to divert the current, and no arc is generated between the switch contacts during the switching process, so as to realize the purpose of arc-free breaking of the switch.

It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, so the present invention includes and is not limited to the embodiments described in the specific implementation, and those skilled in the art according to the technology of the present invention Other implementations derived from the scheme also belong to the protection scope of the present invention.

Claims (7)

1. The utility model provides a dual supply switch arc extinguishing circuit based on power electronic technology, connects on circuit breaker DL1, its characterized in that: the circuit breaker comprises a power electronic module, a load RL1, a diode D2, a capacitor C and a current-limiting resistor R1, wherein the B end of a circuit breaker DL1 is connected with one end of the load RL1, the A end of the circuit breaker DL1 is connected with the current-limiting resistor R1, and the other end of the current-limiting resistor R1 is connected with the B end of the circuit breaker DL1 after being connected with the capacitor C1 in series; the power electronic module is connected between the A end and the B end of the circuit breaker DL1 in parallel; two control ends of the power electronic module are respectively connected between the current-limiting resistor R1 and the capacitor C1 and between the capacitor C1 and the load RL 1.

2. The dual power on Guan Miehu circuit based on power electronic technology of claim 1, wherein: the power electronic module is formed by reversely connecting a power electronic device Q1 and a power electronic device Q2 in series, and the power electronic device Q1 and the power electronic device Q2 are semi-controlled power electronic devices.

3. The dual power on Guan Miehu circuit based on power electronic technology of claim 2, wherein: the power electronic device Q1 and the power electronic device Q2 are provided with diodes, or the power electronic device Q1 and the power electronic device Q2 are respectively connected with a diode D1 and a diode D2 in parallel; power electronics Q1 and diode D2 and power electronics Q2 and diode D1 are all in anti-series relationship.

4. The dual power on Guan Miehu circuit based on power electronic technology of claim 1, wherein: the power electronic module is formed by reversely connecting a power electronic device Q1 and a power electronic device Q2 in parallel, wherein the power electronic device Q1 and the power electronic device Q2 are all fully-controlled power electronic devices.

5. The dual power on Guan Miehu circuit based on power electronic technology of claim 2 or 4, wherein: the power electronic device Q1 and the power electronic device Q2 are IGBT, NPN type triodes or N channel field effect transistors.

6. The dual power on Guan Miehu circuit based on power electronic technology of claim 1, wherein: and an MOV (metal oxide varistor) of a high-voltage arrester group is connected between the end A and the end B of the circuit breaker DL1 in parallel, and the MOV of the high-voltage arrester group forms an energy absorption branch.

7. The dual power on Guan Miehu circuit based on power electronic technology of claim 1, wherein: and the power electronic module is also connected with a delay circuit.

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