Induction power taking circuit, electronic release and intelligent circuit breaker

Abstract

The invention discloses an inductive power taking circuit which is used for an electronic release. The induction power-taking circuit comprises a rectification circuit; the voltage limiting circuit is used for limiting the output voltage of the rectifying circuit below a first voltage threshold value; the energy storage capacitor charging starting circuit is used for converting the output voltage Vp of the voltage limiting circuit into voltage Vs to be output; the voltage Vs output after power-on firstly rises to a third voltage threshold value, then rises to a second voltage threshold value and starts to continuously charge the energy storage capacitor at the moment, and the third voltage threshold value is 1t; a second voltage threshold lt; a first voltage threshold; a trip circuit; and the system power supply generation circuit is used for converting the voltage Vs into the system voltage through a DC / DC conversion circuit, and the starting voltage of the DC / DC conversion circuit is smaller than or equal to a third voltage threshold value. The invention also discloses an electronic release and an intelligent circuit breaker. On the premise of ensuring that the charging voltage of the energy storage capacitor reaches a preset value, the power-on time of the electronic release is remarkably shortened.

Description

Technical Field

[0001] The present invention relates to an inductive power-taking circuit for an electronic trip unit. Background Art

[0002] Intelligent circuit breakers are mainly used in distribution networks to distribute electric energy and protect circuits and power supply equipment from overload, short circuit, ground fault, undervoltage, etc. Intelligent circuit breakers adopt electronic trip units with precise selective protection and multiple functions, and are particularly suitable for distribution networks that require improved power supply reliability and avoid unnecessary power outages. Electronic trip units usually use iron-core current transformers (CTs) to inductively take power from the main circuit current to obtain the system operating power supply and the trip unit power supply. When the main circuit current exceeds the protection setting threshold, the electronic trip unit sends a trip signal to the execution circuit through the trip unit, causing the flux converter to trip, and then driving the actuator to trip the circuit breaker. Electronic trip units are usually configured with energy storage capacitors with relatively large capacities. The iron-core current transformer charges the energy storage capacitor through the inductive output of the main circuit current. The charging voltage of the energy storage capacitor is used to drive the flux converter to act on the one hand, and is used to convert into the system operating power supply of the electronic trip unit on the other hand. Obviously, the flux converter can reliably act only when the charging voltage of the energy storage capacitor reaches the designed predetermined value. Therefore, the existing electronic trip units usually turn on the system operating power supply only when it is judged that the charging voltage of the energy storage reaches the designed predetermined value, and it also takes a certain amount of time to convert the charging voltage of the energy storage capacitor that reaches the predetermined value into the system operating power supply. Therefore, when the electronic trip unit is set with a lower protection threshold and the main circuit current is relatively small at this time, the energy induced and output by the iron-core current transformer is small, the charging of the energy storage capacitor with a relatively large capacity is slow, the duration for the charging voltage of the energy storage capacitor to reach the predetermined value is long, and the system operating power supply is turned on and powered up slowly, ultimately resulting in a slower protection response of the intelligent circuit breaker. Of course, by increasing the inductive output energy of the iron-core current transformer, the charging speed of the energy storage capacitor when the main circuit current is small can be increased, but the disadvantage is that when the main circuit current is large, the output energy of the iron-core current transformer is too large, causing excessive temperature rise of the transformer itself and reducing its reliability in use. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an inductive power-taking circuit that adopts a segmented fast power-up scheme, which can significantly reduce the power-up time of the electronic trip unit on the premise of ensuring that the charging voltage of the energy storage capacitor reaches the predetermined value.

[0004] The present invention specifically adopts the following technical solutions to solve the above technical problems: An induction power-taking circuit is used to inductively take power from the main circuit current by means of a core current transformer to supply an electronic trip unit; the induction power-taking circuit includes: a rectifying circuit for rectifying the output voltage of the core current transformer, and a voltage-limiting circuit for limiting the output voltage of the rectifying circuit below a first voltage threshold; the induction power-taking circuit further includes: A storage capacitor charging and starting circuit for converting the output voltage Vp of the voltage-limiting circuit into a voltage Vs for output; the voltage Vs output by this storage capacitor charging and starting circuit first rises to a third voltage threshold after power-on, and then rises to a second voltage threshold and starts to continuously charge the storage capacitor in the storage capacitor charging and starting circuit at this time, where the third voltage threshold < the second voltage threshold < the first voltage threshold; A tripping circuit for responding to a tripping instruction and driving a flux converter to act to achieve tripping with the voltage Vs; the minimum tripping requirement voltage of the flux converter is equal to the third voltage threshold; A system power generation circuit for converting the voltage Vs into the system voltage VCC of the electronic trip unit through a DC / DC conversion circuit, and the starting voltage of the DC / DC conversion circuit is less than or equal to the third voltage threshold.

[0005] In one embodiment, the storage capacitor charging and starting circuit includes a storage capacitor C2, a capacitor C3, resistors R10 to R12, a diode D14, a diode D15, and a power switch tube V2. The positive electrode of the storage capacitor C2 is connected to the positive output terminal of the voltage-limiting circuit, one end of the resistor R10, and the positive electrode of the diode D15. The negative electrode of the storage capacitor C2 is connected to the other end of the resistor R10 and the input terminal of the power switch tube V2. The control terminal of the power switch tube V2 is connected to one end of the capacitor C3 and the negative electrode of the diode D14. The positive electrode of the diode D14 is connected to one end of the resistor R11 and one end of the resistor R12. The other end of the resistor R11 is connected to the negative electrode of the diode D15 and serves as the voltage Vs output terminal. The other end of the resistor R12 is connected to the other end of the capacitor C3 and the output terminal of the power switch tube V2 and then grounded.

[0006] In one embodiment, the tripping circuit includes a flux converter L1, a diode D13, a power switch tube V3, resistors R13, R14, and a capacitor C4. One end of the flux converter L1 is connected to the voltage Vs output terminal and the negative electrode of the diode D13. The other end of the flux converter L1 is connected to the positive electrode of the diode D13 and the input terminal of the power switch tube V3. The control terminal of the power switch tube V3 is connected to one end of the resistor R13, one end of the resistor R14, and one end of the capacitor C4. The output terminal of the power switch tube V3 is connected to the other end of the resistor R14 and the other end of the capacitor C4 and then grounded. The other end of the resistor R13 is the tripping instruction input terminal.

[0007] In one embodiment, the system power generation circuit includes a smoothing filter circuit, a DC / DC conversion circuit, and a hysteresis comparator circuit. The input terminal of the smoothing filter circuit is connected to the output terminal of the voltage Vs. The output terminal of the smoothing filter circuit is connected to the input terminal of the hysteresis comparator circuit and the input terminal of the DC / DC conversion circuit. The output terminal of the hysteresis comparator circuit is connected to the start / stop signal input terminal of the DC / DC conversion circuit. The output terminal of the DC / DC conversion circuit outputs the system voltage VCC of the electronic release.

[0008] Based on the same inventive concept, the following technical solutions can also be obtained: An electronic release having a power supply circuit for supplying power to the electronic release, the power supply circuit being the induction power taking circuit described in any of the above technical solutions.

[0009] An intelligent circuit breaker including the above-described electronic release.

[0010] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The present invention adopts a segmented fast power-on scheme, which can effectively improve the power-on speed of the working power supply of the electronic release system, improve the energy utilization rate, and significantly reduce the power-on time of the electronic release on the premise of ensuring that the charging voltage of the energy storage capacitor reaches a predetermined value; the technical solution of the present invention can accelerate the protection response speed of the electronic release when powered by a core current transformer, and is particularly suitable for the occasion where the protection threshold of the electronic release is set low and the main circuit current is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a structural block diagram of the induction power taking circuit of the present invention; Figure 2 is a specific implementation circuit diagram of the induction power taking circuit of the present invention; Figure 3 is the power-on timing diagram of the traditional induction power taking circuit; Figure 4 is the power-on timing diagram of the induction power taking circuit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings: The induction power taking circuit of the present invention is used to inductively take power from the main circuit current by using a core current transformer to supply power to the electronic release; its basic circuit structure is as Figure 1 shown, including: A rectifier circuit 1 for rectifying the output voltage of the core current transformer; A voltage limiting circuit 2 for limiting the output voltage Vp of the rectifier circuit to below a first voltage threshold; The energy storage capacitor charging and starting circuit 3 is used to convert the output voltage Vp of the voltage limiting circuit into a voltage Vs for output; after power-on, the voltage Vs output by the energy storage capacitor charging and starting circuit first rises to the third voltage threshold, then rises to the second voltage threshold and starts to continuously charge the energy storage capacitor in the energy storage capacitor charging and starting circuit at this time, and the third voltage threshold < the second voltage threshold < the first voltage threshold; The tripping circuit 4 is used to respond to a tripping instruction and drive the flux converter to act to achieve tripping with the voltage Vs; the minimum tripping voltage requirement of the flux converter is equal to the third voltage threshold; The system power generation circuit 5 is used to convert the voltage Vs into the system voltage VCC of the electronic trip unit through a DC / DC conversion circuit, and the starting voltage of the DC / DC conversion circuit is less than or equal to the third voltage threshold.

[0013] The above-mentioned sub-circuits can be implemented by various existing functional circuits; for the convenience of the public's understanding, the following will be further described in detail with a specific embodiment: The inductive power acquisition circuit of this embodiment is as Figure 2 shown, and includes a rectifier circuit 1, a voltage limiting circuit 2, an energy storage capacitor charging and starting circuit 3, a tripping circuit 4, and a system power generation circuit 5.

[0014] As Figure 2 shown, the rectifier circuit 1 therein is composed of diodes D1~D8, and the outputs of the iron core mutual inductors CT1~CT3 are connected to the rectifier circuit 1, and after being rectified by the diodes D1~D8, they are input to the voltage limiting circuit 2 and filtered by the capacitor C1.

[0015] As Figure 2 shown, the voltage limiting circuit 2 includes a filtering capacitor C1 and a hysteresis comparator circuit with a comparator N1A as the core formed by resistors R1~R9, comparators N1A, zener diodes D10 and D11, and a MOS transistor V1, which is used to limit the output voltage Vp of the rectifier circuit to the voltage threshold V Th1 as follows. The output voltage from the rectifier circuit 1 obtains the voltage Vp through the diode D9, and the voltage Vp obtains the regulated voltage VDD through the resistor R4 and the zener diode D4 as the working power supply of the comparators N1A and N1B; the voltage Vp is divided by the resistors R7 and R8 and input to the non-inverting input terminal 3 of the comparator N1A through the resistor R5, and the voltage Vp obtains the reference voltage Vref through the resistors R9 and the zener diode D11, and Vref is input to the inverting input terminal 2 of the comparator N1A through the resistor R6; the resistor R3 is respectively connected to the non-inverting input terminal 1 and the output terminal 3 of the comparator N1A, the voltage VDD is connected to the output terminal of the comparator N1A, the G terminal of the MOS transistor V1, and one end of the resistor R2 through the resistor R1, and the other end of the resistor R2 is connected to the reference ground.

[0016] As Figure 2As shown in the figure, the energy storage capacitor charging start circuit 3 includes an energy storage capacitor C2, a capacitor C3, resistors R10 to R12, a diode D14, a diode D15, and a power switch tube V2 (a MOS tube in this embodiment). The positive electrode of the energy storage capacitor C2 is connected to the positive output terminal of the voltage limiting circuit, one end of the resistor R10, and the positive electrode of the diode D15. The negative electrode of the energy storage capacitor C2 is connected to the other end of the resistor R10 and the input terminal of the power switch tube V2. The control terminal of the power switch tube V2 is connected to one end of the capacitor C3 and the negative electrode of the diode D14. The positive electrode of the diode D14 is connected to one end of the resistor R11 and one end of the resistor R12. The other end of the resistor R11 is connected to the negative electrode of the diode D15 to serve as the voltage Vs output terminal. The other end of the resistor R12 is connected to the other end of the capacitor C3 and the output terminal of the power switch tube V2 and then grounded. The input of the energy storage capacitor charging start circuit 3 comes from the voltage Vp in the voltage limiting circuit 2. Vp is switched by the diode D15 to obtain the power supply Vs, and Vs is introduced into the voltage dividing circuit composed of the resistors R11 and R12; the resistor R10 is connected in parallel with the energy storage capacitor C2 and then connected in series with the MOS tube V2; when Vs reaches V Th2

[0017] When, the voltage across the resistor R12 causes the level of the G terminal of the MOS tube V2 to reach the triggering condition, and the MOS tube V2 conducts, starting to charge the energy storage capacitor C2. At this time, the voltage Vp first drops and then gradually rises; due to the existence of the anti-shutdown diode D14, the electric power stored in the capacitor C3 keeps the level of the G terminal of the MOS tube V2 at the triggering threshold. Therefore, the MOS tube V2 maintains the conducting state during the inductive power taking process, ensuring sufficient charging of the energy storage capacitor C2; when charging the energy storage capacitor C2, the voltage Vp will drop faster than Vs, causing the diode D15 to be reversely cut off, and the Vs voltage is temporarily higher than Vp; when the Vp voltage rises and is greater than the Vs voltage, the diode D15 conducts forward to boost Vs. Figure 2 ​As shown in the figure, the trip circuit 4 includes a flux converter L1, a diode D13, a power switch tube V3 (a MOS tube in this embodiment), a resistor R13, a resistor R14, and a capacitor C4. One end of the flux converter L1 is connected to the output end of the voltage Vs and the negative electrode of the diode D13. The other end of the flux converter L1 is connected to the positive electrode of the diode D13 and the input end of the power switch tube V3. The control end of the power switch tube V3 is connected to one end of the resistor R13, one end of the resistor R14, and one end of the capacitor C4. The output end of the power switch tube V3 is connected to the other end of the resistor R14 and the other end of the capacitor C4 and then grounded. The other end of the resistor R13 is the trip command input end. The trip power supply of the trip circuit 4 is taken from Vs. Vs is connected to the D end of the MOS tube V3 through the flux converter L1. The diode D13 is connected in parallel across the two ends of the flux converter L1 and is used to quickly release the reverse electromotive force generated when the coil of the flux converter is powered off, protecting the MOS tube V3 from being damaged. The trip signal Trip from the signal processing circuit is divided by the resistors R13 and R14 and filtered by the capacitor C4 and then input to the G end of the MOS tube V3 to control the conduction and cut-off of the MOS tube.

[0018] As Figure 2 shown in the figure, the system power generation circuit 5 includes a smoothing filter circuit, a DC / DC conversion circuit, and a hysteresis comparator circuit. The input end of the smoothing filter circuit is connected to the output end of the voltage Vs. The output end of the smoothing filter circuit is connected to the input end of the hysteresis comparator circuit and the input end of the DC / DC conversion circuit. The output end of the hysteresis comparator circuit is connected to the start / stop signal input end of the DC / DC conversion circuit. The output end of the DC / DC conversion circuit outputs the system voltage VCC of the electronic trip unit. The system power generation circuit 5 receives the voltage Vs output from the energy storage capacitor charging start circuit 3. Vs is input to the DC / DC conversion circuit after being smoothed by the capacitors C5 to C6. The DC / DC converter N2, the capacitors C5 to C10, the inductor L2, and the fast recovery diode D12 are configured to form a DC / DC conversion circuit with the DC / DC converter N2 as the core. The resistors R15 to R21 and the comparator N1B are configured to form a hysteresis comparator circuit with the comparator N1B as the core, serving as the start control circuit of the DC / DC conversion circuit. The hysteresis comparator circuit starts the DC / DC conversion circuit to output the system voltage VCC when the voltage Vs reaches the voltage threshold V Th3 and shuts down the system power supply VCC when it is lower than the voltage threshold V Th4 .

[0019] Figure 3 and Figure 4 respectively show the power-on timing diagrams of the traditional inductive power-taking circuit without adopting the segmented power-on scheme and the inductive power-taking circuit of the present invention adopting the segmented power-on scheme. Both use the same relatively small main circuit current, mainly for the protection response when the protection threshold of the electronic trip unit is set relatively low.

[0020] Figure 3 When Vs reaches V th3 the DC / DC converter is started to output the system power supply VCC. V th3 is also the minimum required voltage for the flux converter to trip; ton is the time consumed for the DC / DC converter to start outputting VCC after the ON / OFF terminal gets a high level; tp is the shortest time consumed from when the system power supply VCC is powered on to when the trip command is issued, mainly including the power-on reset time, software initialization time, AD sampling calculation time, etc. of the electronic trip unit microprocessor, which belongs to the fixed consumed time. Under normal circumstances, the energy consumed in a short time when the flux converter trips is much larger than the power consumption of other functional circuits. Therefore, the energy storage capacitor capacity is generally several times that of the DC / DC converter input capacitor. When the inductive power-taking circuit without the segmented power-on scheme is powered on, the energy storage capacitor and the DC / DC converter input capacitor are charged together, and the rising slopes of the voltages Vp and Vs are small. The time consumed from applying current to the main circuit to the electronic trip unit issuing the trip command is T2.

[0021] As Figure 4 shown, the inductive power-taking circuit adopts a segmented power-on scheme. It is set that the system-generated power supply circuit 5 starts the DC / DC converter to generate the system power supply prior to the energy storage capacitor charging start circuit 3 starting to charge the energy storage capacitor. Since the input capacitor capacity in the system-generated power supply circuit 5 is much smaller than the energy storage capacitor capacity, the rising slopes of the voltages Vp and Vs are faster. When Vs reaches V th3 the DC / DC converter is started to output the system power supply VCC. The voltages Vp and Vs have a small drop due to loading, but due to the overall small load, the voltages Vp and Vs rise rapidly again. When Vs rises to reach V th2 the charging of the energy storage capacitor starts. Due to the large capacity of the energy storage capacitor, the voltage Vp drops rapidly. Due to the presence of the diode D15 in the energy storage capacitor charging start circuit 3, it prevents the voltage Vs from charging the energy storage capacitor, and the voltage Vs drops more slowly, causing the diode D15 to be reversely cut off; during this period, since the system-generated power supply circuit 5 is provided with a hysteresis comparator circuit, when Vs drops but is still greater than V th4 the system power supply VCC is still maintained. When the voltage Vp gradually rises higher than the voltage Vs, the diode D15 conducts forward, causing Vs and Vp to rise together. The signal processing circuit of the electronic trip unit issues a trip command after a time interval tp after being powered on; it should be noted that Figure 4 although the voltage Vs of the energy storage capacitor corresponding to the trip is less than Figure 3 , but it is greater than the minimum required voltage V th3 of the flux converter to trip, so it is ensured that reliable tripping can be achieved. Figure 4 in the time consumed from applying current to the main circuit to the electronic trip unit issuing the trip command is T1. Compared withFigure 3 The time for issuing the tripping instruction is fast (T2 - T1), obviously this is related to Figure 4 After adopting the segmented power - on scheme, it is greatly related to improving the energy utilization rate. By Figure 4 This scheme can significantly accelerate the protection response speed of the electronic release, and is especially suitable for the occasions where the protection threshold of the electronic release is set low and the main circuit current is small.

Claims

1. An inductive power circuit, used to use an iron core current transformer to inductively draw power from the main circuit current to supply an electronic release; the inductive power circuit comprises: A rectifier circuit for rectifying the output voltage of the core current transformer, and a voltage limiting circuit for limiting the output voltage of the rectifier circuit to below a first voltage threshold; characterized in that the inductive power supply circuit also includes: The energy storage capacitor charging start circuit is used to convert the output voltage Vp of the voltage limiting circuit into a voltage Vs output; after power-on, the voltage Vs output by the energy storage capacitor charging start circuit first rises to a third voltage threshold, then rises to a second voltage threshold and starts to continuously charge the energy storage capacitor in the energy storage capacitor charging start circuit at this time, and the third voltage threshold < the second voltage threshold < the first voltage threshold; A tripping circuit, for responding to a tripping instruction, driving a magnetic flux converter to trip with a voltage Vs; the minimum required tripping voltage of the magnetic flux converter is equal to a third voltage threshold; The system power generation circuit is used to convert the voltage Vs into the system voltage VCC of the electronic release through a DC / DC conversion circuit, and the starting voltage of the DC / DC conversion circuit is less than or equal to a third voltage threshold.

2. The induction power supply circuit according to claim 1, characterized in that: The energy storage capacitor charging start circuit includes an energy storage capacitor C2, a capacitor C3, resistors R10-R12, a diode D14, a diode D15, and a power switch tube V2. The positive electrode of the energy storage capacitor C2 is connected to the positive output end of the voltage limiting circuit, one end of the resistor R10, and the positive electrode of the diode D15. The negative electrode of the energy storage capacitor C2 is connected to the other end of the resistor R10 and the input end of the power switch tube V2. The control end of the power switch tube V2 is connected to one end of the capacitor C3 and the negative electrode of the diode D14. The positive electrode of the diode D14 is connected to one end of the resistor R11 and one end of the resistor R12. The other end of the resistor R11 is connected to the negative electrode of the diode D15 and serves as the output end of the voltage Vs. The other end of the resistor R12 is connected to the other end of the capacitor C3 and the output end of the power switch tube V2 and then grounded.

3. The induction power supply circuit according to claim 1, characterized in that: The tripping circuit includes a flux converter L1, a diode D13, a power switch tube V3, a resistor R13, a resistor R14, and a capacitor C4. One end of the flux converter L1 is connected to the output end of the voltage Vs and the negative electrode of the diode D13, the other end of the flux converter L1 is connected to the positive electrode of the diode D13 and the input end of the power switch tube V3, the control end of the power switch tube V3 is connected to one end of the resistor R13, one end of the resistor R14, and one end of the capacitor C4, the output end of the power switch tube V3 is connected to the other end of the resistor R14 and the other end of the capacitor C4 and then grounded, and the other end of the resistor R13 is the tripping command input end.

4. The induction power extraction circuit according to claim 1, characterized in that: The system power generation circuit includes a smoothing filter circuit, a DC / DC conversion circuit, and a hysteresis comparator circuit. The input end of the smoothing filter circuit is connected to the voltage Vs output end, the output end of the smoothing filter circuit is connected to the input end of the hysteresis comparator circuit and the input end of the DC / DC conversion circuit, the output end of the hysteresis comparator circuit is connected to the start / stop signal input end of the DC / DC conversion circuit, and the output end of the DC / DC conversion circuit outputs the system voltage VCC of the electronic release.

5. An electronic trip device having a power supply circuit for supplying power to the electronic trip device, characterized in that: The power supply circuit is the induction power supply circuit as claimed in any one of claims 1 to 4.

6. An intelligent circuit breaker, characterized in that: Comprising the electronic release as claimed in claim 5.

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