NE555 pre-charging protection circuit with precise time sequence control

Abstract

The invention discloses an NE555 pre-charging protection circuit with precise time sequence control, which belongs to the technical field of electronic circuits and comprises a power supply module, a dual NE555 time sequence control module, a pre-charging loop, a main contactor control loop, a driving module and a protection circuit. The dual NE555 time sequence control module adopts two NE555 chips to respectively control time sequence actions of a pre-charging relay and a main contactor: when the dual NE555 time sequence control module is powered on, the pre-charging relay is immediately closed to pre-charge a capacitor; after 2.64 seconds, the pre-charging relay is switched off, and a main contactor control loop is triggered at the same time; and the main contactor is closed after 2.2 seconds of time delay, and the whole power-on time sequence control is completed. By accurately controlling the time sequence of the relay and the contactor, the power-on impact is effectively inhibited, and the method is suitable for high-reliability application scenes such as industrial motor driving and new energy storage systems with strict time sequence control requirements.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electronic circuits, in particular to a NE555 pre-charge protection circuit with precise timing control. BACKGROUND

[0002] In a large-current load driving system, the impact current generated by direct power-on is easy to damage the power supply and load devices. The traditional pre-charge circuit can only suppress the initial impact and cannot meet the multi-stage timing control requirements under complex working conditions. For example, in some industrial equipment, the pre-charge loop needs to be closed first to charge the capacitor, and after a delay, the pre-charge loop is opened and the main contactor is closed. This precise timing control is crucial for system stability and life, but the existing technical solutions have problems such as insufficient timing accuracy, high circuit complexity, and high cost. SUMMARY

[0003] The technical task of the application is to solve the above problems, and provide a NE555 pre-charge protection circuit with precise timing control. By precisely controlling the timing of the relay and the contactor, the power-on impact is effectively suppressed, and the circuit is suitable for high-reliability application scenarios such as industrial motor driving and new energy storage systems that require strict timing control.

[0004] The technical solution adopted by the application to solve the technical problems is:

[0005] A NE555 pre-charge protection circuit with precise timing control, comprising: a power supply module, a double-NE555 timing control module, a pre-charge circuit, a main contactor control circuit, a driving module, and a protection circuit.

[0006] The double-NE555 timing control module uses two NE555 chips to control the timing action of the pre-charge relay and the main contactor: when powered on, the pre-charge relay is immediately closed to pre-charge the capacitor; after 2.64 seconds, the pre-charge relay is opened, and the main contactor control circuit is triggered; the main contactor is closed after a 2.2-second delay, completing the entire power-on timing control.

[0007] The circuit realizes precise timing control through double-NE555 chips, effectively suppresses the large-current load power-on impact in combination with the pre-charge circuit, improves the system reliability and stability, and is particularly suitable for application scenarios such as industrial automation equipment and new energy power conversion systems that require strict timing control.

[0008] Further, the power supply module is a 12V / 2A DC power supply,

[0009] An SCT2A25STER high-efficiency switching power supply is used to provide stable power supply for the system, with an output ripple of ≤50mV and overcurrent and overvoltage protection functions.

[0010] Further, the double NE555 timing control module, specifically includes:

[0011] NE555-1, for pre-charging relay control, including:

[0012] Timing element: select 24kΩ resistance and 100μF electrolytic capacitor, according to the formula T = 1.1RC calculated delay time is about equal to 2.64 seconds;

[0013] Output control: output (OUT) through SS8050 transistor drive pre-charging relay coil;

[0014] NE555-2, for main contactor control, including:

[0015] Timing element: select 20kΩ resistance and 100μF electrolytic capacitor, according to the formula T = 1.1RC calculated delay time is about equal to 2.2 seconds;

[0016] Output control: output (OUT) through SS8550 transistor drive pre-charging relay coil.

[0017] Further, the pre-charging circuit, including:

[0018] Pre-charging relay (K1): select HF32FV-G / 12-HSTF, coil voltage 12V, contact capacity 10A / 250VAC, used to control the pre-charging circuit on-off;

[0019] Current limiting resistor (R1): select 50Ω PTC thermistor, limit pre-charging current, ensure that the initial impact current ≤5A.

[0020] Further, the initial impact current is limited to 2.4A, then

[0021] Current limiting resistor R = 60V / 2.4A = 25Ω.

[0022] Further, the main contactor control circuit, including:

[0023] Main contactor (K2): select Schneider HF32FV-G / 12-HSTF, coil voltage 12V, main contact capacity 12A / 250VAC, used to control the contactor of the main power supply of the load;

[0024] Protection diode (D2): select US2M, to protect the drive circuit from the back electromotive force generated when the contactor coil is powered off.

[0025] Further, the protection circuit, using TVS diode (SMBJ12CA), parallel in the NE555 power input, for suppressing surge voltage, protection NE555 chip.

[0026] Further, the NE555 pre-charge protection circuit works as follows:

[0027] (1) Power-on stage:

[0028] Pre-charge start: at the moment of power-on, NE555-1 is triggered and outputs a high level, the pre-charge relay K1 is immediately closed, and the current charges the load capacitor through the current-limiting resistor R1, and the initial impact current is limited within 1.2 A;

[0029] 2.64 second delay: NE555-1 starts timing, and the timing element RC determines the delay time to be 2.64 seconds;

[0030] End of pre-charge: after 2.64 seconds, NE555-1 outputs a low level, the pre-charge relay K1 is disconnected, and the pre-charge stage ends;

[0031] (2) Main contactor closing stage:

[0032] Trigger NE555-2: at the moment of power-on, trigger NE555-2 to start timing;

[0033] 2.2 second delay: NE555-2 realizes 2.2 second delay through its timing element RC;

[0034] Close the main contactor: after the delay ends, NE555-2 outputs a high level to drive the main contactor K2 to close, and the load enters the normal working state.

[0035] Further, the circuit debugging and optimization method includes timing accuracy calibration: using an oscilloscope to monitor the NE555 output end waveform, adjusting the trimmer timing resistor value, to ensure the delay accuracy.

[0036] Further, in actual tests, the 2.64 second delay error is controlled within ±10 ms, and the 2.2 second delay error is controlled within ±10 ms.

[0037] Compared with the prior art, the NE555 pre-charge protection circuit with precise timing control has the following beneficial effects:

[0038] 1. Precise timing control: the double-NE555 circuit realizes precise timing control of the pre-charge relay and the main contactor, and the timing error is ≤±5 ms.

[0039] 2. High-efficiency impact suppression: the pre-charge circuit reduces the initial impact current by more than 80%, effectively protecting the power supply and load devices.

[0040] 3. Reliability improvement: adopting redundant protection design and combining with TVS diode, the circuit reliability is improved by more than 30%. DETAILED DESCRIPTION

[0041] Figure 1 is the NE555 pre-charge protection circuit power supply circuit principle diagram provided by the embodiment of the application with precise timing control;

[0042] Figure 2 is the NE555 pre-charge protection circuit principle diagram provided by the embodiment of the application with precise timing control;

[0043] Figure 3 is the timing control waveform diagram provided by the embodiment of the application. DETAILED DESCRIPTION

[0044] The application will be further described below in combination with specific embodiments.

[0045] The embodiment of the application provides a NE555 pre-charge protection circuit with precise timing control, adopts a NE555 chip to realize multi-stage timing control, has a power-on pre-charge function, realizes large-current load driving, effectively suppresses power-on impact by precisely controlling the timing of a relay and a contactor, and is suitable for industrial motor driving, new energy storage systems and other high-reliability application scenarios with strict timing control requirements.

[0046] The circuit is composed of a 12V / 2A power module, a double-NE555 timing control module, a pre-charge circuit, a main contactor control circuit, a driving module and a protection circuit.

[0047] The double-NE555 timing control module adopts two NE555 chips to control the timing actions of the pre-charge relay and the main contactor: when powered on, the pre-charge relay is immediately closed for capacitor pre-charge; after 2.64 seconds, the pre-charge relay is disconnected, and the main contactor control circuit is triggered at the same time; the main contactor is closed after 2.2 seconds of delay, and the whole power-on timing control is completed.

[0048] In combination with Figure 1 and Figure 2 , the circuit devices and functions are as follows:

[0049] 1, power module.

[0050] 12V / 2A DC power supply: adopt SCT2A25STER high-efficiency switching power supply to provide stable power supply for the system, with output ripple ≤50mV, and overcurrent and overvoltage protection functions.

[0051] 2, double-NE555 timing control module.

[0052] Two NE555 chips are adopted to realize 2.64-second and 2.2-second delay control respectively:

[0053] (1) NE555-1 (pre-charge relay control)

[0054] Timing element: 24kΩ resistor and 100μF electrolytic capacitor are selected, and the delay time is about 2.64 seconds according to the formula T=1.1RC.

[0055] Output control: the output end (OUT) drives the pre-charging relay coil through the SS8050 triode.

[0056] (2) NE555-2 (main contactor control)

[0057] Timing element: 20kΩ resistor and 100μF electrolytic capacitor are selected, and the delay time is about 2.2 seconds.

[0058] Output control: the output end (OUT) drives the pre-charging relay coil through the SS8550 triode.

[0059] 3. Pre-charging circuit.

[0060] Pre-charging relay (K1): HF32FV-G / 12-HSTF is selected, coil voltage 12V, contact capacity 10A / 250VAC, used to control the pre-charging circuit on-off.

[0061] Current limiting resistor (R1): 50Ω PTC thermistor is selected to limit the pre-charging current, and ensure that the initial impact current is ≤5A.

[0062] 4. Main contactor control circuit.

[0063] Main contactor (K2): Schneider HF32FV-G / 12-HSTF is selected, coil voltage 12V, main contact capacity 12A / 250VAC, used to control the contactor of the main power supply of the load.

[0064] Protection diode (D2): US2M is selected to protect the drive circuit from the back electromotive force generated when the contactor coil is powered off.

[0065] 5. Protection circuit.

[0066] TVS diode (SMBJ12CA): connected in parallel with the input end of the NE555 power supply, to suppress surge voltage and protect the NE555 chip.

[0067] Figure 1 The power supply circuit diagram of the NE555 pre-charging protection circuit is shown in detail, which shows the circuit of converting SCT2A25STER into 12V power supply. Figure 2 The circuit diagram shows the connection relationship of the double-NE555 timing control module, pre-charging circuit and main contactor control circuit in detail.

[0068] The working process of the circuit is as follows:

[0069] 1. Power-on stage:

[0070] (1)Precharge start: the moment the power is turned on, NE555-1 is triggered and outputs high level, precharge relay K1 is immediately closed, and the current charges the load capacitor through current-limiting resistor R1, the initial impact current is limited to within 1.2A.

[0071] (2) 2.64 seconds delay: NE555-1 starts timing, and the timing element RC determines the delay time to be 2.64 seconds.

[0072] (3) Precharge end: after 2.64 seconds, NE555-1 outputs low level, precharge relay K1 is disconnected, and the precharge phase ends.

[0073] 2, main contactor closing phase:

[0074] (1) Trigger NE555-2: the moment the power is turned on, trigger NE555-2 starts timing.

[0075] (2) 2.2 seconds delay: NE555-2 realizes 2.2 seconds delay through its timing element RC.

[0076] (2) Close main contactor: after the delay ends, NE555-2 outputs high level, drives main contactor K2 to close, and the load enters normal working state.

[0077] Figure 3 The timing control waveform diagram of the NE555 precharge protection circuit is shown in the figure, which clearly shows the action timing of the precharge relay and the main contactor. The blue color is the precharge output, and it can be found that there is a precharge output at power on, and the precharge is closed after 2.4 seconds delay by NE555. The yellow color is the main contactor control end, which is opened after 2.2 seconds delay by NE555, completing the precharge function.

[0078] In this embodiment, the device selection and parameter calculation method is as follows:

[0079] 1, NE555 timing element calculation:

[0080] Precharge delay 2.64 seconds: R=24kΩ, C=100μF, T=1.1×24kΩ×100μF≈2.64 seconds;

[0081] Main contactor delay 2 seconds: R=20kΩ, C=100μF, T=1.1×20kΩ×100μF≈680 milliseconds.

[0082] 2, current-limiting resistor calculation:

[0083] Initial impact current is limited to 2.4A: R=60V / 2.4A=25Ω.

[0084] The circuit debugging and optimization method is as follows:

[0085] Timing accuracy calibration:

[0086] Using an oscilloscope to monitor the NE555 output waveform, fine-tune the timing resistance value, ensure the delay accuracy.

[0087] In actual test, 2.64 second delay error is controlled within ±10ms, and 2.2 second delay error is controlled within ±10ms.

[0088] The application realizes precise timing control through double NE555 chips, effectively suppresses power-on impact of large current load in combination with a pre-charge circuit, improves system reliability and stability, and is particularly suitable for application scenarios such as industrial automation equipment, new energy power conversion systems and other application scenarios with strict timing control requirements.

[0089] Through the above specific embodiments, the skilled in the art can easily implement the present application. However, it should be understood that the present application is not limited to the above specific embodiments. On the basis of the disclosed embodiments, the skilled in the art can arbitrarily combine different technical features to realize different technical solutions.

[0090] In addition to the technical features described in the specification, all are known technologies for professionals.

Claims

1. A NE555 pre-charge protection circuit with accurate timing control, characterized in that, The application relates to a power module, a double-NE555 timing control module, a pre-charging circuit, a main contactor control circuit, a driving module and a protection circuit. The double-NE555 timing control module adopts two NE555 chips to control the timing actions of a pre-charging relay and a main contactor, that is, when power is turned on, the pre-charging relay is immediately closed to pre-charge a capacitor; the pre-charging relay is disconnected after 2.64 seconds, and a main contactor control circuit is triggered at the same time; and the main contactor is closed after a 2.2-second delay, thereby completing the whole power-on timing control. The power module is a 12V / 2A direct-current power supply.

2. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, An SCT2A25STER high-efficiency switching power supply is adopted to provide stable power supply for the system, the output ripple is less than or equal to 50mV, and the system has overcurrent and overvoltage protection functions. The double-NE555 timing control module specifically comprises:

3. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, NE555-1 which is used for pre-charging relay control and comprises: a timing element: 24kOmega resistance and 100muF electrolytic capacitor are selected, and the delay time is calculated to be equal to 2.64 seconds according to the formula T=1.1RC; output control: an output end drives a pre-charging relay coil through an SS8050 triode; NE555-2 which is used for main contactor control and comprises: a timing element: 20kOmega resistance and 100muF electrolytic capacitor are selected, and the delay time is calculated to be equal to 2.2 seconds according to the formula T=1.1RC; output control: an output end drives a pre-charging relay coil through an SS8550 triode. The pre-charging circuit comprises:

4. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, a pre-charging relay: an HF32FV-G / 12-HSTF is selected, the coil voltage is 12V, the contact capacity is 10A / 250VAC, and the pre-charging relay is used for controlling the on-off of a pre-charging circuit; a current-limiting resistor: a 50Omega PTC thermistor is selected to limit the pre-charging current and ensure that the initial impact current is less than or equal to 5A. The initial impact current is limited to 2.4A, so that 5. The NE555 pre-charge protection circuit with precise timing control according to claim 1 or 4, characterized in that, the current-limiting resistor R=60V / 2.4A=25Omega. The main contactor control circuit comprises:

6. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, a main contactor: an HF32FV-G / 12-HSTF is selected, the coil voltage is 12V, the main contact capacity is 12A / 250VAC, and the main contactor is used for controlling the contactor of a main power supply of a load; a protection diode: a US2M is selected to protect the driving circuit from the back electromotive force generated when the contactor coil is powered off. The protection circuit adopts a TVS diode which is connected in parallel with the NE555 power supply input end and is used for suppressing surge voltage and protecting the NE555 chip.

7. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, The NE555 pre-charging protection circuit works as follows:

8. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, (1) power-on stage: pre-charging starting: when power is turned on, NE555-1 is triggered and outputs a high level, a pre-charging relay K1 is immediately closed, a current charges a load capacitor through a current-limiting resistor R1, and the initial impact current is limited to be less than or equal to 1.2A; 2.64-second delay: NE555-1 starts timing, and the timing element RC determines the delay time to be 2.64 seconds; pre-charging ending: after 2.64 seconds, NE555-1 outputs a low level, the pre-charging relay K1 is disconnected, and the pre-charging stage is ended; (2) main contactor closing stage: triggering NE555-2: when power is turned on, NE555-2 is triggered to start timing; ​ 2.2 seconds delay: NE555-2 realizes 2.2 seconds delay through its timing element RC; Close the main contactor: after the delay ends, the NE555-2 output high level, drive the main contactor K2 closed, the load into normal working state.

9. The NE555 pre-charge protection circuit with precise timing control according to claim 1, characterized in that, The debugging and optimization of the circuit includes timing accuracy calibration: use oscilloscope to monitor the NE555 output waveform, adjust the trimmer timing resistance value, to ensure the delay accuracy.

10. The NE555 pre-charge protection circuit with precise timing control according to claim 9, characterized in that, In actual test, 2.64 seconds delay error is controlled within ±10ms, 2.2 seconds delay error is controlled within ±10ms.

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