A low-voltage direct-current circuit breaker based on a hollow inductor
By inserting a hollow inductor in series in the negative circuit of the circuit breaker, short-circuit protection is achieved using voltage pulse detection, which solves the problem of slow response of conventional circuit breakers, reduces costs, and is suitable for low-voltage DC power distribution systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGZHOU METRO GRP CO LTD
- Filing Date
- 2025-08-21
- Publication Date
- 2026-08-04
AI Technical Summary
Conventional mechanical circuit breakers cannot effectively respond to the extremely short duration of short-circuit pulses in low-voltage DC power distribution systems, resulting in high costs for smart circuit breakers and limiting their application.
A hollow inductor is inserted in series in the negative circuit of the circuit breaker. The short circuit is detected by the voltage pulse generated during the short circuit. The circuit breaker can be quickly operated through the pulse detection circuit and the tripping circuit, thus avoiding dependence on current sensors, AD sampling circuits and CPUs.
It achieves low-cost short-circuit protection, has a simple structure, is suitable for low-voltage DC power distribution systems, reduces equipment costs, and is suitable for widespread application.
Smart Images
Figure CN224596140U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of low-voltage DC power distribution technology, specifically relating to a low-voltage DC circuit breaker based on a hollow inductor. Background Technology
[0002] When a short circuit occurs at the output of a DC-DC converter (AC-to-DC or DC-to-DC converter), the short-circuit pulse duration is extremely short, possibly only tens of microseconds or hundreds of microseconds. After the capacitor at the converter's output terminal is fully discharged, the short-circuit pulse disappears, and the converter immediately stops outputting or limits current output. At this time, there is no current or very little current in the short-circuit loop, which cannot trigger the circuit breaker to operate. The conventional method is to use a smart circuit breaker (a conventional mechanical circuit breaker with a smart control module) to sample and detect the short-circuit current. However, because the short-circuit pulse duration is short, the smart circuit breaker's sampling and processing circuit needs a high sampling frequency, and the corresponding CPU processing power of the smart circuit breaker also needs to be increased. This makes the cost of smart circuit breakers high, limiting their application in low-voltage DC power distribution. Utility Model Content
[0003] The purpose of this invention is to provide a low-voltage DC circuit breaker based on a hollow inductor, which can achieve short-circuit protection with a short short-circuit current pulse time at a lower cost.
[0004] The purpose of this utility model is achieved through the following technical measures: a low-voltage DC circuit breaker based on a hollow inductor, characterized in that a hollow inductor is added to the side of the negative moving contact of the circuit breaker near the load, the hollow inductor is connected in series with the negative circuit, and the input and output terminals of the hollow inductor are respectively connected to the two input terminals of the pulse detection circuit of the internal control circuit of the circuit breaker.
[0005] This invention utilizes a hollow inductor connected in series with the negative terminal of the circuit breaker to generate a voltage pulse during a short circuit. Upon detecting the voltage pulse, the circuit breaker control circuit outputs a control to close the trip coil circuit, thereby achieving short-circuit protection. This solves the problem that conventional thermal-magnetic circuit breakers cannot operate effectively due to the short duration of the short-circuit current pulse. Moreover, compared with smart circuit breakers, this invention does not require the addition of current sensors, AD sampling circuits, CPUs, etc., and can achieve short-circuit protection for short-circuit current pulses at a lower cost.
[0006] The internal control circuit of the circuit breaker described in this utility model includes a power conversion circuit, a pulse detection circuit, and a tripping circuit. The power conversion circuit is introduced from the positive and negative terminals of the circuit breaker input, and after conversion, it supplies power to the pulse detection circuit and the tripping circuit. A supercapacitor is configured at the output terminal of the power conversion circuit. This supercapacitor is used to supply power to the pulse detection circuit and the tripping circuit when a short circuit occurs. After the circuit breaker is opened and the power supply is restored, the power conversion circuit charges the supercapacitor back to its normal operating voltage, so that it can supply power to the pulse detection circuit and the tripping circuit when the next short circuit occurs. The two input terminals of the pulse detection circuit are respectively connected to the input and output terminals of the hollow inductor. When a short circuit occurs in the circuit, the rate of change of the circuit current generates a pulse voltage across the hollow inductor. After receiving this pulse signal, the pulse detection circuit determines that a short circuit has occurred, closes the tripping relay, and after the tripping relay is closed, the tripping circuit is turned on. The current in the tripping coil establishes a magnetic field, magnetizing the core of the trip unit, thereby attracting the armature to move upward. The armature pushes the lever upward, thereby separating the hook from the chain and disconnecting the main circuit of the circuit breaker.
[0007] The internal structure of the circuit breaker described in this utility model includes power take-off points located at the positive and negative input poles of the main circuit, upper main contacts at the positive and negative poles, a moving contact linked to a chain, lower main contacts at the positive and negative poles, a hollow inductor, a circuit breaker heating element, a bimetallic strip, a lever, a coil, a trip unit core, an armature, a hook, a chain, and a spring for providing power after the chain and hook are separated. The upper main contacts at the positive and negative poles are connected to the power take-off point and the moving contact at their respective ends. The other end of the moving contact is connected to the lower main contacts at the positive and negative poles. The hollow inductor is connected to the lower main contact at the negative pole and the circuit breaker heating element at its respective ends. The metal plate is located above the heating element of the circuit breaker, the lever is located above the bimetallic strip and linked with it, the coil is sleeved on the trip unit core, the coil is connected to the internal control circuit of the circuit breaker, the armature is located below the trip unit core, one end of which is connected to the trip unit core and the other end is linked with the lever, the hook is located above the lever and linked with it, one end of the hook is hinged to a rotating shaft fixed inside the circuit breaker, and the other end is engaged with one end of a chain, the other end of which is connected to one end of a spring, and the other end of the spring is fixed inside the circuit breaker.
[0008] Compared with the prior art, the present invention has the following significant advantages:
[0009] (1) This utility model uses an air-core inductor connected in series with the negative terminal of the circuit breaker to generate a voltage pulse during a short circuit. After detecting the voltage pulse, the circuit breaker control circuit outputs a control to close the trip coil circuit, thereby achieving short-circuit protection. This solves the problem that conventional thermal-magnetic circuit breakers cannot operate effectively due to the short duration of the short-circuit current pulse. Moreover, compared with smart circuit breakers, this utility model does not require the addition of current sensors, AD sampling circuits, CPUs, etc., and can achieve short-circuit protection for loads powered by DC converters in current low-voltage DC power distribution at a lower cost, which is conducive to the promotion of low-voltage DC power distribution applications.
[0010] (2) When the hollow inductor of this utility model is connected in series in the circuit, its resistance is similar to that of the circuit cable and its loss is low.
[0011] (3) This utility model has a simple structure, low cost, and strong practicality, and is suitable for widespread promotion and use. Attached Figure Description
[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0013] Figure 1 This is a schematic diagram of the internal control circuit of the circuit breaker of this utility model;
[0014] Figure 2 This is a schematic diagram of the internal structure of the circuit breaker of this utility model.
[0015] In the diagram: 1-moving contact, 2-lower main contacts of positive and negative poles, 3-circuit breaker heating element, 4-bimetallic strip, 5-lever, 6-coil, 7-tripper core, 8-armature, 9-hook, 10-chain, 11-spring, 12-upper main contacts of positive and negative poles, 13-power take-off point, 14-shaft, 15-circuit breaker, 16-load, 17-circuit breaker internal control circuit. Detailed Implementation
[0016] like Figure 1 , Figure 2 As shown, this utility model discloses a low-voltage DC circuit breaker 15 based on a hollow inductor. A hollow inductor L is added to the side of the negative moving contact 1 of the circuit breaker near the load 16. The hollow inductor L is connected in series with the negative circuit, and the input terminal X1 and output terminal X2 of the hollow inductor L are respectively connected to the two input terminals of the pulse detection circuit of the internal control circuit of the circuit breaker.
[0017] When a short circuit occurs in the downstream circuit of the circuit breaker, the instantaneous and significant change in the short-circuit current will generate a voltage pulse. The air-core inductor L is connected at both ends to send a short-circuit pulse into the pulse detection circuit. After the pulse detection circuit detects the short-circuit pulse, it outputs a signal to close the circuit breaker's trip coil circuit, causing the circuit breaker to trip. For conventional DC overload currents, thermal tripping of the circuit breaker is still used.
[0018] The internal control circuit of the circuit breaker includes a power conversion circuit, a pulse detection circuit, and a tripping circuit. The power conversion circuit is introduced from the positive and negative terminals of the circuit breaker input, and after conversion, it supplies power to the pulse detection circuit and the tripping circuit. A small supercapacitor is configured at the output of the power conversion circuit. This supercapacitor is used to supply power to the pulse detection circuit and the tripping circuit when a short circuit occurs. After the circuit breaker opens and the power supply is restored, the power conversion circuit charges the supercapacitor back to its normal operating voltage, so that it can supply power to the pulse detection circuit and the tripping circuit when the next short circuit occurs. The two input terminals of the pulse detection circuit are connected to the input X1 and output X2 of the hollow inductor, respectively. When a short circuit occurs, the circuit current with a large rate of change generates a pulse voltage across the hollow inductor. After receiving this pulse signal, the pulse detection circuit determines that a short circuit has occurred, closes the tripping relay, and after the tripping relay closes, the tripping circuit is activated. The current in the tripping coil establishes a magnetic field, magnetizing the core of the trip unit, thereby attracting the armature to move upward. The armature pushes the lever upward, thereby separating the hook from the chain and disconnecting the main circuit of the circuit breaker.
[0019] The internal structure of the circuit breaker includes a power take-off point 13 located at the positive and negative input terminals of the main circuit, upper main contacts 12 at the positive and negative terminals, a moving contact 1 linked to a chain 10, lower main contacts 2 at the positive and negative terminals, a hollow inductor L, a circuit breaker heating element 3, a bimetallic strip 4, a lever 5, a coil 6, a trip unit core 7, an armature 8, a hook 9, a chain 10, and a spring 11 for providing power after the chain 10 and hook 9 are separated. The two ends of the upper main contacts 12 are connected to the power take-off point 13 and the moving contact 1, respectively. The other end of the moving contact 1 is connected to the lower main contacts 2 at the positive and negative terminals. The two ends of the hollow inductor L are connected to the lower main contacts at the negative terminal and the circuit breaker heating element, respectively. The heating element 3 and bimetallic strip 4 are located above the heating element 3 of the circuit breaker. The lever 5 is located above the bimetallic strip 4 and is linked with it. The coil 6 is sleeved on the trip unit core 7 and is connected to the internal control circuit 17 of the circuit breaker. The armature 8 is located below the trip unit core 7. One end of the armature is connected to the trip unit core 7 and the other end is linked with the lever 5. The hook 9 is located above the lever 5 and is linked with it. One end of the hook 9 is hinged to the rotating shaft 14 fixed inside the circuit breaker and the other end is engaged with one end of the chain 10. The other end of the chain 10 is connected to one end of the spring 11 and the other end of the spring 11 is fixed inside the circuit breaker.
[0020] This utility model provides load short circuit protection and overload protection. The short circuit protection process is as follows: a short circuit occurs in the circuit → the hollow inductor generates a voltage pulse → the pulse detection circuit detects the pulse and outputs it → the trip circuit closes, the trip unit attracts the armature to move upward, pushes the lever to move upward, the lever pushes the hook to move upward → after the hook moves upward into place, the chain disengages → the circuit breaker disconnects.
[0021] The overload protection process is as follows: Overload occurs in the circuit → the heating element of the circuit breaker heats up and the bimetallic strip begins to expand → the expansion of the bimetallic strip of the circuit breaker pushes the lever upward, the lever pushes the hook upward → after the hook moves upward into place, the chain disengages → the circuit breaker disconnects.
[0022] The embodiments of this utility model are not limited thereto. Based on the above content of this utility model, and in accordance with the common technical knowledge and conventional means in the field, without departing from the basic technical idea of this utility model, this utility model can also be modified, replaced or changed in various other forms, all of which fall within the scope of protection of this utility model.
Claims
1. A low-voltage DC circuit breaker based on an air-core inductor, characterized in that: An air-core inductor is added to the negative moving contact of the circuit breaker near the load side. The air-core inductor is connected in series with the negative circuit, and the input and output terminals of the air-core inductor are respectively connected to the two input terminals of the pulse detection circuit of the internal control circuit of the circuit breaker.
2. The low-voltage DC circuit breaker based on an air-core inductor according to claim 1, characterized in that: The internal control circuit of the circuit breaker includes a power conversion circuit, a pulse detection circuit, and a tripping circuit. The power conversion circuit is introduced from the positive and negative terminals of the circuit breaker input, and after conversion, it is sent to the pulse detection circuit and the tripping circuit. A supercapacitor is configured at the output terminal of the power conversion circuit.
3. The low-voltage DC circuit breaker based on an air-core inductor according to claim 2, characterized in that: The internal structure of the circuit breaker includes power take-off points located at the positive and negative input poles of the main circuit, upper main contacts at the positive and negative poles, a moving contact linked to a chain, lower main contacts at the positive and negative poles, a hollow inductor, a circuit breaker heating element, a bimetallic strip, a lever, a coil, a trip unit core, an armature, a hook, a chain, and a spring for providing power after the chain and hook are separated. The upper main contacts at the positive and negative poles are connected to the power take-off point and the moving contact at their respective ends. The other end of the moving contact is connected to the lower main contacts at the positive and negative poles. The hollow inductor is connected to the lower main contact at the negative pole and the circuit breaker heating element at its respective ends. The bimetallic strip... The bimetallic strip is located above the heating element of the circuit breaker. The lever is located above the bimetallic strip and is linked with it. The coil is sleeved on the trip unit core and is connected to the internal control circuit of the circuit breaker. The armature is located below the trip unit core, with one end connected to the trip unit core and the other end linked with the lever. The hook is located above the lever and is linked with it. One end of the hook is hinged to a rotating shaft fixed inside the circuit breaker, and the other end is engaged with one end of a chain. The other end of the chain is connected to one end of a spring, and the other end of the spring is fixed inside the circuit breaker.