A transformer open circuit protection circuit for primary and secondary split current protection equipment

Abstract

The present invention discloses a mutual inductor open circuit protection circuit for a primary and secondary split current protection device, comprising: a mutual inductor T1, a mutual inductor forward output open circuit protection circuit and a mutual inductor reverse output open circuit protection circuit; the primary side of the mutual inductor T1 is electrically connected to the input end, the secondary side of the mutual inductor T1 is electrically connected to the mutual inductor forward output open circuit protection circuit and the mutual inductor reverse output open circuit protection circuit respectively, the mutual inductor forward output open circuit protection circuit is electrically connected to each output end of the mutual inductor reverse output open circuit protection circuit respectively; the mutual inductor T1 is a current mutual inductor. The present invention solves the technical problems of circuit damage and personal danger caused by the open circuit of the main body mutual inductor when the primary and secondary split current protection device is replaced under power, and the low control accuracy and timeliness of the protection circuit.

Description

Technical Field

[0001] The invention relates to the technical field of electric power distribution, and in particular to a mutual inductor open circuit prevention circuit for primary and secondary split current protection equipment. Background Art

[0002] The primary and secondary split current protection equipment includes the new primary and secondary split structure intelligent low-voltage circuit breakers defined by the State Grid. The primary and secondary split structure low-voltage intelligent circuit breakers integrate the primary unit, which is mainly composed of mechanical, electrical and necessary sensor components of the low-voltage intelligent circuit breaker, and the secondary unit, which is mainly composed of electronic circuits such as control, protection and communication, and are designed and assembled in two shells. The primary unit and the secondary unit are assembled in an assembled manner. The secondary unit has independent plug-in replacement, and the communication module supports hot-swap operation. When the secondary unit of the above-mentioned low-voltage intelligent circuit breaker is replaced under power, the transformer of the main body will open, and the transformer open circuit voltage will reach more than 200V. The high voltage will damage the secondary unit circuit and is more likely to cause personal injury risks to the operation and maintenance personnel. At present, many current transformer open circuit protection designs basically adopt structural short circuit and electronic circuit control. The structural short circuit method is adopted. When the secondary part is separated from the shrapnel on the structure, the secondary output part of the transformer is short-circuited with a metal shrapnel. This method is simple, but has a slow closing speed, a short open circuit, and occupies a large space. As for the circuit control principle, the current mainstream adopts the thyristor short-circuit open circuit method to achieve open circuit protection. The thyristor can only close the open circuit protection at the zero point, and the time accuracy is low. Capacitors and voltage regulators are generally used to generate drive signals and start control thresholds. The capacitors have low accuracy and change with the environment, which will cause low voltage accuracy in the start control of the anti-open circuit circuit. Connecting capacitors to the circuit will increase the parasitic capacitance of the circuit, affecting the measurement accuracy of the transformer's post-stage sampling circuit.

[0003] The patent document with application number CN202120077281.6 discloses an open circuit protection circuit for a current transformer, including a secondary coil of a current transformer, and the open circuit protection circuit for the current transformer also includes a bidirectional thyristor, the secondary coil of the current transformer is used to connect the T1 pole and G pole trigger circuit of the bidirectional thyristor, the T1 pole and T2 pole of the bidirectional thyristor are used for short-circuiting the secondary coil of the current transformer, and a capacitor is connected between the G pole of the bidirectional thyristor and the T2 pole of the bidirectional thyristor. This scheme uses capacitors to draw power, and the capacitor drawing power is related to the material properties of the capacitor itself, and there is a large discreteness, which will lead to low control accuracy or unstable voltage. In addition, the thyristor has a zero-crossing medium and low control accuracy, which cannot meet the requirements of high precision and high timeliness. Therefore, it is urgent to propose a transformer open circuit protection circuit for a primary and secondary split current protection device to solve the technical problems of circuit damage and personal danger caused by the open circuit of the main transformer when the existing primary and secondary split current protection device is replaced with power, as well as the low control accuracy and timeliness of the protection circuit. Summary of the invention

[0004] The main purpose of the present invention is to propose a transformer open circuit protection circuit for primary and secondary split current protection devices, aiming to solve the technical problems of circuit damage and personal danger caused by the open circuit of the main transformer when the existing primary and secondary split current protection devices are replaced under power, as well as the low control accuracy and timeliness of the protection circuit.

[0005] To achieve the above-mentioned purpose, the present invention provides a transformer open circuit protection circuit for a primary and secondary split current protection device, wherein the transformer open circuit protection circuit for a primary and secondary split current protection device includes: a transformer T1, a transformer forward output open circuit protection circuit and a transformer reverse output open circuit protection circuit; the primary side of the transformer T1 is electrically connected to the input end, the secondary side of the transformer T1 is electrically connected to the transformer forward output open circuit protection circuit and the transformer reverse output open circuit protection circuit respectively, and the transformer forward output open circuit protection circuit is electrically connected to each output end of the transformer reverse output open circuit protection circuit respectively; the transformer T1 is a current transformer.

[0006] One of the preferred schemes, the mutual inductor forward output open circuit protection circuit includes a diode D4, a MOS tube Q1, an adjustable voltage regulator D2, a resistor R1 and a mutual inductor forward output voltage divider circuit; the anode of the diode D4 is respectively connected to the drain of the MOS tube Q1, the mutual inductor reverse output open circuit protection circuit, the 2nd pin of the adjustable voltage regulator D2 and the mutual inductor forward output voltage divider circuit, the cathode of the diode D4 is respectively connected to the mutual inductor and the mutual inductor reverse output open circuit protection circuit, the source of the MOS tube Q1 is respectively connected to the mutual inductor reverse output open circuit protection circuit, the resistor R1, the mutual inductor forward output voltage divider circuit and the output end, the gate of the MOS tube Q1 is respectively connected to the resistor R1 and the 1st pin of the adjustable voltage regulator D2, and the 3rd pin of the adjustable voltage regulator is connected to the mutual inductor forward output voltage divider circuit.

[0007] In one of the preferred schemes, the transformer forward output voltage divider circuit includes a resistor R2 and a resistor R3; one end of the resistor R2 is connected to the source of the MOS tube Q1, and the other end of the resistor R2 is respectively connected to the 3 pins of the adjustable voltage source D2 and the resistor R3, and the other end of the resistor R3 is connected to the anode of the diode D4.

[0008] In one of the preferred solutions, the MOS transistor Q1 is a P-channel MOS transistor.

[0009] In one of the preferred solutions, the forward output voltage of the mutual inductor forward output open circuit protection circuit is:

[0010]

[0011] Among them, Voutp is the transformer forward output voltage, V ref1 is the reference voltage of the adjustable voltage source D2, R2 and R3 are the resistance values ​​of resistors R2 and R3 respectively, V df1 is the forward conduction voltage drop of diode D4.

[0012] One of the preferred schemes, the mutual inductor reverse output open circuit protection circuit includes a diode D1, a MOS tube Q2, an adjustable voltage regulator D3, a resistor R5 and a mutual inductor reverse output voltage divider circuit; the anode of the diode D1 is respectively connected to the mutual inductor forward output open circuit protection circuit, the drain of the MOS tube Q2, the 2 pins of the adjustable voltage regulator D3 and the mutual inductor reverse output voltage divider circuit, the cathode of the diode D1 is respectively connected to the mutual inductor and the mutual inductor forward output open circuit protection circuit, the source of the MOS tube Q2 is respectively connected to the mutual inductor forward output open circuit protection circuit, the resistor R5, the mutual inductor reverse output voltage divider circuit and the output end, the gate of the MOS tube Q2 is respectively connected to the 1 pin of the adjustable voltage regulator D3 and the resistor R5, and the 3 pin of the adjustable voltage regulator D3 is connected to the mutual inductor reverse output voltage divider circuit.

[0013] In one of the preferred schemes, the mutual inductor reverse output voltage divider circuit includes a resistor R4 and a resistor R6; one end of the resistor R4 is connected to the anode of the diode D1, and the other end of the resistor R4 is respectively connected to the 3-pin of the adjustable voltage source D3 and the resistor R6, and the other end of the resistor R6 is connected to the source of the MOS tube Q2.

[0014] In one of the preferred solutions, the MOS transistor Q2 is a P-channel MOS transistor.

[0015] In one of the preferred solutions, the reverse output voltage of the mutual inductor reverse output open circuit protection circuit is:

[0016]

[0017] Among them, V outq is the reverse output voltage of the transformer, V ref2 is the reference voltage of the adjustable voltage source D3, R4 and R5 are the resistance values ​​of resistors R4 and R5 respectively, V df2 is the forward conduction voltage drop of diode D1.

[0018] In the above technical solution of the present invention, the transformer open circuit protection circuit for the primary and secondary split current protection device includes: a transformer T1, a transformer forward output open circuit protection circuit and a transformer reverse output open circuit protection circuit; the primary side of the transformer T1 is electrically connected to the input end, the secondary side of the transformer T1 is electrically connected to the transformer forward output open circuit protection circuit and the transformer reverse output open circuit protection circuit respectively, the transformer forward output open circuit protection circuit is electrically connected to each output end of the transformer reverse output open circuit protection circuit respectively; the transformer T1 is a current transformer. The present invention solves the technical problems of the existing primary and secondary split current protection device, that is, the open circuit of the main transformer leads to circuit damage and personal danger when the main transformer is replaced under power, and the protection circuit has low control accuracy and timeliness.

[0019] In the present invention, a dual MOS tube is used as a short-circuit switch, which has a fast response speed, is not affected by the zero point, and has high control accuracy. Among them, a high-precision adjustable voltage source is used as feedback control, the open-circuit protection speed is fast, and the transformer open-circuit clamping voltage is set by configuring a transformer forward output voltage divider circuit and a transformer reverse output voltage divider circuit, and the voltage setting accuracy is high. The entire circuit does not need to be set with filtering and energy storage capacitors, and the measurement accuracy will not be affected by the increase of parasitic capacitance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0021] Figure 1 It is a first schematic diagram of a transformer open circuit prevention circuit for a primary-secondary split current protection device according to an embodiment of the present invention;

[0022] Figure 2 A second schematic diagram of a transformer open circuit prevention circuit for a primary-secondary split current protection device according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of output waveforms of a transformer according to an embodiment of the present invention in which a transformer open circuit prevention circuit is not provided;

[0024] Figure 4 A schematic diagram of output waveforms of a transformer anti-open circuit circuit provided in a transformer according to an embodiment of the present invention.

[0025] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0028] See also Figure 1-Figure 4 According to one aspect of the present invention, the present invention provides a transformer open circuit protection circuit for a primary-secondary split current protection device, wherein the transformer open circuit protection circuit for a primary-secondary split current protection device comprises: a transformer T1, a transformer forward output open circuit protection circuit and a transformer reverse output open circuit protection circuit; the primary side of the transformer T1 is electrically connected to the input end, the secondary side of the transformer T1 is electrically connected to the transformer forward output open circuit protection circuit and the transformer reverse output open circuit protection circuit respectively, and the transformer forward output open circuit protection circuit is electrically connected to each output end of the transformer reverse output open circuit protection circuit respectively; the transformer T1 is a current transformer.

[0029] Specifically, in this embodiment, the input terminal connected to the primary side of the transformer T1 is Iin, which represents an input current signal, and the output terminal is Iout, which represents a secondary signal output by the transformer.

[0030] Specifically, in the present embodiment, the mutual inductor forward output open circuit protection circuit comprises a diode D4, a MOS tube Q1, an adjustable voltage regulator D2, a resistor R1 and a mutual inductor forward output voltage divider circuit; the anode of the diode D4 is respectively connected to the drain of the MOS tube Q1, the mutual inductor reverse output open circuit protection circuit, the 2nd pin of the adjustable voltage regulator D2 and the mutual inductor forward output voltage divider circuit, the cathode of the diode D4 is respectively connected to the mutual inductor and the mutual inductor reverse output open circuit protection circuit, the source of the MOS tube Q1 is respectively connected to the mutual inductor reverse output open circuit protection circuit, the resistor R1, the mutual inductor forward output voltage divider circuit and the output end, the gate of the MOS tube Q1 is respectively connected to the resistor R1 and the 1st pin of the adjustable voltage regulator D2, and the 3rd pin of the adjustable voltage regulator is connected to the mutual inductor forward output voltage divider circuit.

[0031] Specifically, in this embodiment, the mutual inductor forward output voltage divider circuit includes a resistor R2 and a resistor R3; one end of the resistor R2 is connected to the source of the MOS tube Q1, and the other end of the resistor R2 is respectively connected to the 3 pin of the adjustable voltage source D2 and the resistor R3, and the other end of the resistor R3 is connected to the anode of the diode D4; the mutual inductor reverse output voltage divider circuit includes a resistor R4 and a resistor R6; one end of the resistor R4 is connected to the anode of the diode D1, and the other end of the resistor R4 is respectively connected to the 3 pin of the adjustable voltage source D3 and the resistor R6, The other end of the resistor R6 is connected to the source of the MOS tube Q2; the transformer open-circuit output voltage is set by adjusting the resistance values ​​of the resistors R2, R3, R4 and R6, wherein the resistance value of the resistor R2 is equal to the resistance value of the resistor R4, the resistance value of the resistor R3 is equal to the resistance value of the resistor R6, the forward and reverse clamping voltages of the transformer forward output voltage divider circuit and the transformer reverse output voltage divider circuit are the same, and the transformer open-circuit clamping voltage is set by setting the transformer forward output voltage divider circuit and the transformer reverse output voltage divider circuit, and the voltage setting accuracy is high.

[0032] Specifically, in this embodiment, the resistor R2 and the resistor R3 are connected to the reference electrode of the adjustable voltage source D2. When the voltage divided by the resistor R2 and the resistor R3 is higher than the reference voltage V of the adjustable voltage source D2, ref1 When the voltage divided by resistors R2 and R3 is lower than the reference voltage V of the adjustable voltage source D2, the A and K poles of the adjustable voltage source D2 are turned on, that is, the 2 and 1 pins of the adjustable voltage source D2 are turned on, and the MOS tube Q1 is turned on; when the voltage divided by resistors R2 and R3 is lower than the reference voltage V of the adjustable voltage source D2, ref1 When , the A and K poles of the adjustable voltage source D2 are cut off, that is, the 2 and 1 pins of the adjustable voltage source D2 are cut off, and the MOS tube Q1 is cut off; the forward output voltage of the mutual inductor forward output open circuit protection circuit is:

[0033]

[0034] Among them, V outp is the transformer forward output voltage, V ref1 is the reference voltage of the adjustable voltage source D2, R2 and R3 are the resistance values ​​of resistors R2 and R3 respectively, V df1 is the forward conduction voltage drop of diode D4.

[0035] Specifically, in the present embodiment, the mutual inductor reverse output open circuit protection circuit comprises a diode D1, a MOS tube Q2, an adjustable voltage regulator D3, a resistor R5 and a mutual inductor reverse output voltage divider circuit; the anode of the diode D1 is respectively connected to the mutual inductor forward output open circuit protection circuit, the drain of the MOS tube Q2, the 2 pins of the adjustable voltage regulator D3 and the mutual inductor reverse output voltage divider circuit, the cathode of the diode D1 is respectively connected to the mutual inductor and the mutual inductor forward output open circuit protection circuit, the source of the MOS tube Q2 is respectively connected to the mutual inductor forward output open circuit protection circuit, the resistor R5, the mutual inductor reverse output voltage divider circuit and the output end, the gate of the MOS tube Q2 is respectively connected to the 1 pin of the adjustable voltage regulator D3 and the resistor R5, and the 3 pins of the adjustable voltage regulator D3 are connected to the mutual inductor reverse output voltage divider circuit.

[0036] Specifically, in this embodiment, the resistors R4 and R6 are connected to the reference electrode of the adjustable voltage source D3. When the voltage divided by the resistors R4 and R6 is higher than the reference voltage V of the adjustable voltage source D3, ref2 When the voltage divided by resistors R4 and R6 is lower than the reference voltage V of the adjustable voltage source D3, the A and K poles of the adjustable voltage source D3 are turned on, that is, the 2 and 1 pins of the adjustable voltage source D3 are turned on, and the MOS tube Q2 is turned on; when the voltage divided by resistors R4 and R6 is lower than the reference voltage V of the adjustable voltage source D3, ref2 When , the A and K poles of the adjustable voltage source D3 are cut off, that is, the 2 and 1 pins of the adjustable voltage source D3 are cut off, and the MOS tube Q2 is cut off; the reverse output voltage of the mutual inductor reverse output open circuit protection circuit is:

[0037]

[0038] Among them, V outq is the reverse output voltage of the transformer, V ref2 is the reference voltage of the adjustable voltage source D3, R4 and R5 are the resistance values ​​of resistors R4 and R5 respectively, V df2 is the forward conduction voltage drop of diode D1.

[0039] Specifically, in this embodiment, the MOS transistor Q2 is a P-channel MOS transistor, the MOS transistor Q1 is a P-channel MOS transistor, the MOS transistor Q1 and the diode D4 form a forward open current short-circuit path, and the MOS transistor Q2 and the diode D1 form a reverse open current short-circuit path. Since the current carrying capacity of the body diodes of the MOS transistors Q1 and Q2 is limited, the current carrying capacity is increased by connecting the diodes D1 and D4 in parallel.

[0040] Specifically, in this embodiment, see the attached Figure 3 This is a schematic diagram of the output waveform of the transformer without a transformer open circuit protection circuit. Figure 4The output waveform diagram of the transformer open circuit prevention circuit of the present invention is set for the transformer, and the voltage output by the transformer is: V outq ≤V out ≤V outp When the secondary unit is separated from the main body, the output voltage of the transformer is limited to below the safe voltage through the circuit of the present invention, thereby avoiding damage to the secondary unit circuit caused by high voltage and personal injury to the operation and maintenance personnel; the present invention adopts a simple electronic circuit with a small volume, and by setting a dual MOS tube as a short-circuit switch, the response speed is fast, and it is not affected by the zero point, the control accuracy is high, and a high-precision adjustable voltage source is used as feedback control, the open circuit protection speed is fast, and the transformer open circuit clamping voltage is set by setting a transformer forward output voltage divider circuit and a transformer reverse output voltage divider circuit, and the setting voltage accuracy is high; wherein, the transformer anti-open circuit circuit described in the present invention does not need to set filtering and energy storage capacitors, and will not increase parasitic capacitance to affect the measurement accuracy.

[0041] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A transformer open circuit protection circuit for primary and secondary split current protection equipment, characterized in that: include: Transformer T1, transformer forward output open circuit protection circuit and transformer reverse output open circuit protection circuit; the primary side of the transformer T1 is electrically connected to the input end, the secondary side of the transformer T1 is electrically connected to the transformer forward output open circuit protection circuit and the transformer reverse output open circuit protection circuit respectively, the transformer forward output open circuit protection circuit is electrically connected to each output end of the transformer reverse output open circuit protection circuit respectively; the transformer T1 is a current transformer.

2. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 1, characterized in that: The mutual inductor forward output open circuit protection circuit comprises a diode D4, a MOS tube Q1, an adjustable voltage regulator D2, a resistor R1 and a mutual inductor forward output voltage divider circuit; the anode of the diode D4 is respectively connected to the drain of the MOS tube Q1, the mutual inductor reverse output open circuit protection circuit, the 2nd pin of the adjustable voltage regulator D2 and the mutual inductor forward output voltage divider circuit, the cathode of the diode D4 is respectively connected to the mutual inductor and the mutual inductor reverse output open circuit protection circuit, the source of the MOS tube Q1 is respectively connected to the mutual inductor reverse output open circuit protection circuit, the resistor R1, the mutual inductor forward output voltage divider circuit and the output end, the gate of the MOS tube Q1 is respectively connected to the resistor R1 and the 1st pin of the adjustable voltage regulator D2, and the 3rd pin of the adjustable voltage regulator is connected to the mutual inductor forward output voltage divider circuit.

3. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 2 is characterized in that: The transformer forward output voltage divider circuit includes a resistor R2 and a resistor R3; one end of the resistor R2 is connected to the source of the MOS tube Q1, the other end of the resistor R2 is respectively connected to the 3 pins of the adjustable voltage source D2 and the resistor R3, and the other end of the resistor R3 is connected to the anode of the diode D4.

4. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 2 is characterized in that: The MOS transistor Q1 is a P-channel MOS transistor.

5. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 3 is characterized in that: The forward output voltage of the mutual inductor forward output open circuit protection circuit is: Among them, V outp is the transformer forward output voltage, V ref1 is the reference voltage of the adjustable voltage source D2, R2 and R3 are the resistance values ​​of resistors R2 and R3 respectively, V df1 is the forward conduction voltage drop of diode D4.

6. A transformer open circuit prevention circuit for primary and secondary split current protection equipment according to any one of claims 1 to 5, characterized in that: The mutual inductor reverse output open circuit protection circuit comprises a diode D1, a MOS tube Q2, an adjustable voltage regulator D3, a resistor R5 and a mutual inductor reverse output voltage divider circuit; the anode of the diode D1 is respectively connected to the mutual inductor forward output open circuit protection circuit, the drain of the MOS tube Q2, the 2nd pin of the adjustable voltage regulator D3 and the mutual inductor reverse output voltage divider circuit, the cathode of the diode D1 is respectively connected to the mutual inductor and the mutual inductor forward output open circuit protection circuit, the source of the MOS tube Q2 is respectively connected to the mutual inductor forward output open circuit protection circuit, the resistor R5, the mutual inductor reverse output voltage divider circuit and the output end, the gate of the MOS tube Q2 is respectively connected to the 1st pin of the adjustable voltage regulator D3 and the resistor R5, and the 3rd pin of the adjustable voltage regulator D3 is connected to the mutual inductor reverse output voltage divider circuit.

7. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 6, characterized in that: The reverse output voltage divider circuit of the mutual inductor includes a resistor R4 and a resistor R6; one end of the resistor R4 is connected to the anode of the diode D1, and the other end of the resistor R4 is respectively connected to the 3 pins of the adjustable voltage source D3 and the resistor R6, and the other end of the resistor R6 is connected to the source of the MOS tube Q2.

8. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 6, characterized in that: The MOS transistor Q2 is a P-channel MOS transistor.

9. The transformer open circuit prevention circuit for primary and secondary split current protection equipment according to claim 7, characterized in that: The reverse output voltage of the mutual inductor reverse output open circuit protection circuit is: Among them, V outq is the reverse output voltage of the transformer, V ref2 is the reference voltage of the adjustable voltage source D3, R4 and R5 are the resistance values ​​of resistors R4 and R5 respectively, V df2 is the forward conduction voltage drop of diode D1.

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