Molded case controller and enhanced reset circuit thereof

Abstract

The utility model discloses a molded case controller and an enhanced reset circuit thereof. The circuit comprises a voltage division circuit, a reset chip and a dummy load circuit. The reset chip takes power from a first direct-current power supply through the voltage division circuit; the output end of the reset chip is connected with the reset input end of the microprocessor of the molded case controller; the dummy load circuit comprises a semiconductor switch tube and a load resistor; the semiconductor switch tube and the load resistor are connected in series and bridged between a system power supply and a signal ground to form a discharge loop, a control end of the semiconductor switch tube is connected with an output end of the reset chip, and when the reset chip is in an undervoltage state, a reset signal is output, and the dummy load circuit is in a conducting state to discharge energy in the system power supply. The circuit can accelerate the current discharge of a system power supply in a reset state, and reduces the risk of false tripping of a molded case controller caused by unstable system work due to voltage fluctuation; the circuit is simple in structure and easy to integrate.

Description

Technical Field

[0001] The utility model relates to the field of circuit breaker controllers, in particular to a molded case controller and an enhanced reset circuit thereof. Background Art

[0002] The molded case controller is an electrical device used to implement four protection functions: long delay overload, short delay short circuit, instantaneous short circuit and ground fault.

[0003] Existing molded case controllers generally only have a reset circuit. In practical applications, when the working current at the load end of the molded case is critical to the minimum working current of the controller and the load changes, and the voltage obtained by the molded case controller fluctuates around the system working threshold voltage, the system will become unstable and may cause the molded case controller to trip by mistake. Utility Model Content

[0004] In view of the above-mentioned defects of the prior art, the utility model provides an enhanced reset circuit of a molded case controller, which can reduce the risk of system operation instability caused by voltage fluctuations, thereby causing the molded case controller to trip incorrectly.

[0005] The technical solution is as follows:

[0006] An enhanced reset circuit of a molded case controller comprises a voltage divider circuit, a reset chip and a dummy load circuit;

[0007] The reset chip draws power from the first DC power supply through the voltage divider circuit;

[0008] The output end of the reset chip is connected to the reset input end of the microprocessor of the molded case controller and the control end of the dummy load circuit;

[0009] The dummy load circuit includes a semiconductor switch tube and a load resistor; the semiconductor switch tube and the load resistor are connected in series and bridged between the system power supply and the signal ground to form a leakage loop; the control end of the semiconductor switch tube is connected to the output end of the reset chip, and when the reset chip is undervoltage, a reset signal is output, and the dummy load circuit is in a conducting state; when the reset chip resumes normal power supply, the reset signal jumps, and the dummy load circuit is in a shut-off state;

[0010] The system power supply is obtained by stepping down the voltage of the first direct current power supply and is used to power the microprocessor.

[0011] Furthermore, the reset chip is a low voltage reset chip, the semiconductor switch tube is a PNP transistor or a PMOS tube, its base is connected to the output end of the reset chip, its emitter is connected to the system power supply, and its collector is connected to the signal ground through a resistor.

[0012] Furthermore, the reset chip is a high voltage reset chip, the semiconductor switch tube is an NPN transistor or an NMOS tube, its base is connected to the output end of the reset chip, its emitter is connected to the signal ground, and its collector is connected to the system power supply through a resistor.

[0013] Furthermore, the voltage divider circuit includes a first resistor, a second resistor, and a first capacitor; the first resistor is connected across the first DC power supply and the power input terminal of the reset chip; the second resistor and the first capacitor are connected in parallel and connected across the power input terminal of the reset chip and the signal ground.

[0014] Furthermore, the output end of the reset chip is also connected to the signal ground via a second capacitor.

[0015] Furthermore, the first DC power supply is 12V.

[0016] Furthermore, the system power supply is 3.3V.

[0017] The utility model also provides a plastic shell controller, and the technical solution is as follows:

[0018] A molded case controller comprises: a microprocessor and a reset circuit; the reset circuit is the enhanced reset circuit as described above.

[0019] Furthermore, the molded case controller also includes: a voltage stabilizing circuit, a rectifying and discharging circuit, a mutual inductance power taking circuit, a sampling circuit, a tripping circuit, an alarm circuit, an indication circuit and a communication interface circuit;

[0020] The mutual inductance power taking circuit is connected to the current transformer, and is used to take power from at least one phase of each phase line of the power line, and generate a first DC power supply through the rectification and leakage circuit; the first DC power supply is then generated into the system power supply through the voltage stabilizing circuit;

[0021] The sampling circuit is connected to the current transformer and is used to condition the current sampling signal and send it to the microprocessor;

[0022] The tripping circuit is connected to the tripper and is used to perform a tripping operation according to the instruction of the microprocessor;

[0023] The communication interface circuit is connected to the microprocessor and is used for communication connection between the microprocessor and a host computer.

[0024] The utility model achieves the following technical effects:

[0025] The enhanced reset circuit can accelerate the current discharge of the system power supply in the reset state, reduce the risk of system instability caused by voltage fluctuations, and further cause the molded case controller to trip accidentally.

[0026] The enhanced reset circuit has a simple circuit structure and is easy to integrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the circuit schematic diagram of the plastic case controller;

[0028] Figure 2 It is an enhanced reset circuit of the utility model. DETAILED DESCRIPTION

[0029] To further illustrate each embodiment, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in this field should be able to understand other possible implementations and advantages of the present invention.

[0030] The utility model is now further described in conjunction with the accompanying drawings and specific implementation methods.

[0031] like Figure 1 As shown, the utility model provides a circuit principle block diagram of a molded case controller, which is composed of a processor circuit, a voltage stabilizing circuit, a rectifying and current discharging circuit, a mutual inductance power circuit, a sampling circuit, a tripping circuit, an alarm circuit, an indicating circuit, a communication interface circuit and other circuits.

[0032] In this embodiment, the processor circuit uses a 32-bit ARM processor as the core processor unit, collects the current of each phase A / B / C / N of the circuit breaker through a current transformer, generates a 12V power supply for the tripping circuit through a rectification and leakage circuit, and generates a 3.3V power supply through a secondary voltage stabilization circuit to power the processor circuit, communication interface circuit, operational amplifier circuit and other circuits.

[0033] After the current sampling signal of the current transformer is processed by the sampling circuit low-pass filter circuit and the operational amplifier circuit, the processor circuit collects the current value of each phase, and reads the protection current and time setting value of each section corresponding to the coding switch in real time. The processor circuit performs calculations based on the current and the corresponding setting value, and issues corresponding tripping or alarm instructions based on the tripping current and time agreement required by the technical requirements. The internal or external flux release or electronic release is activated through the tripping circuit, disconnecting the main circuit power supply or issuing a corresponding sound and light alarm.

[0034] The communication interface circuit adopts the standard RS485 interface and ModBus-RTU protocol, which can realize the functions of remote real-time viewing of current, fault records and setting value data, remote opening, communication test tripping, etc.

[0035] like Figure 2As shown, U1 is a microprocessor (i.e., MCU) in the processor circuit. The reset circuit of the microprocessor U1 is composed of a reset chip U9, sampling resistors R53, R54, a switch tube Q3, and a load resistor R48 to form an enhanced reset circuit with reset and dummy load functions. The output end of U9 is connected to the reset end of U1 and controls the on and off of the dummy load circuit. When the reset chip U9 detects that the self-powered voltage divided by the resistors R53 and R54 is lower than the threshold voltage of the system operation, it outputs a low-level reset signal NRST to put U1 in a reset state; at the same time, Q3 is turned on, and the energy storage of the system power supply DVDD is consumed through the load resistor R48 to stop the system from working, preventing the system from being unstable. When it is detected that the self-powered voltage is greater than the threshold voltage of the system operation, the reset signal NRST jumps from a low level to a high level to realize the reset function of the microprocessor. In addition, Q3 is cut off, and the dummy load circuit is turned off to avoid the dummy load circuit from increasing the system power consumption, and the system power supply is more sufficient.

[0036] The enhanced reset circuit has the following advantages: it can accelerate the current discharge of the system power supply in the reset state, reduce the risk of system instability caused by voltage fluctuations, and thus cause the molded case controller to trip inadvertently; the circuit structure is simple and easy to integrate.

[0037] Although the present invention has been specifically demonstrated and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes may be made to the present invention in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An enhanced reset circuit for a molded case controller, characterized in that: Including voltage divider circuit, reset chip and dummy load circuit; The reset chip draws power from the first DC power supply through the voltage divider circuit; The output end of the reset chip is connected to the reset input end of the microprocessor of the molded case controller and the control end of the dummy load circuit; The dummy load circuit includes a semiconductor switch tube and a load resistor; the semiconductor switch tube and the load resistor are connected in series and bridged between the system power supply and the signal ground to form a leakage loop; the control end of the semiconductor switch tube is connected to the output end of the reset chip, and when the reset chip is undervoltage, a reset signal is output, and the dummy load circuit is in a conducting state; when the reset chip resumes normal power supply, the reset signal jumps, and the dummy load circuit is in a shut-off state; The system power supply is obtained by stepping down the voltage of the first direct current power supply and is used to power the microprocessor.

2. The enhanced reset circuit according to claim 1, characterized in that: The reset chip is a low voltage reset chip, the semiconductor switch tube is a PNP transistor or a PMOS tube, the base of which is connected to the output end of the reset chip, the emitter of which is connected to the system power supply, and the collector of which is connected to the signal ground through a resistor.

3. The enhanced reset circuit according to claim 1, wherein: The reset chip is a high voltage reset chip, the semiconductor switch tube is an NPN transistor or an NMOS tube, the base of which is connected to the output end of the reset chip, the emitter of which is connected to the signal ground, and the collector of which is connected to the system power supply through a resistor.

4. The enhanced reset circuit according to claim 1, wherein: The voltage divider circuit includes a first resistor, a second resistor, and a first capacitor; the first resistor is connected across the first DC power supply and the power input terminal of the reset chip; the second resistor and the first capacitor are connected in parallel and connected across the power input terminal of the reset chip and the signal ground.

5. The enhanced reset circuit according to claim 1, wherein: The output end of the reset chip is also connected to the signal ground via a second capacitor.

6. The enhanced reset circuit according to claim 1, characterized in that: The first DC power supply is 12V.

7. The enhanced reset circuit according to claim 1, characterized in that: The system power supply is 3.3V.

8. A plastic shell controller, comprising: A microprocessor and a reset circuit; the reset circuit is an enhanced reset circuit as described in any one of claims 1 to 7.

9. The molded case controller according to claim 8, characterized in that: Also includes: Voltage stabilization circuit, rectification and discharge circuit, mutual inductance power circuit, sampling circuit, tripping circuit, alarm circuit, indication circuit and communication interface circuit; The mutual inductance power taking circuit is connected to the current transformer, and is used to take power from at least one phase of each phase line of the power line, and generate a first DC power supply through the rectification and leakage circuit; the first DC power supply is then generated into the system power supply through the voltage stabilizing circuit; The sampling circuit is connected to the current transformer and is used to condition the current sampling signal and send it to the microprocessor; The tripping circuit is connected to the tripper and is used to perform a tripping operation according to the instruction of the microprocessor; The communication interface circuit is connected to the microprocessor and is used for communication connection between the microprocessor and a host computer.

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