A switching power supply safety control system

Abstract

The application discloses a kind of switching power supply safety control systems, and safety control system includes voltage comparison circuit, reference voltage selection circuit and control circuit;Voltage comparison circuit includes voltage input module and comparator, the positive input end of comparator is connected to input voltage, the reverse input end of comparator is connected to voltage input module output end, and the input end of voltage input module is connected to reference voltage;Reference voltage selection circuit includes reversible counter module and decoder module, reversible counter module output end is connected with the input end of decoder module;Control circuit includes positive slope detection module, line removal detection and discharge control circuit module and timer module, and positive slope detection module output end is connected with line removal detection and discharge control circuit module and timer module, and timer module output end is connected with line removal detection and discharge control circuit module, and discharge control circuit module output end is connected with timer module and positive slope detection module.

Description

Technical Field

[0001] This invention belongs to the technical field of switching power supply control systems, and particularly relates to a switching power supply safety control system. Background Technology

[0002] AC-DC switching power supplies are high-frequency power conversion devices with AC power input. Safety authorities require that their input filter capacitors be discharged after the AC line voltage is removed, and there are relevant safety regulations and standards.

[0003] The commonly used resistor network discharge scheme results in significant input power loss in various modes. Using an active input filter capacitor can effectively reduce input power loss. Traditional solutions typically employ capacitors to suppress power supply electromagnetic interference and do not require an external discharge resistor network. However, capacitor discharge usually requires specific conditions for activation, and the continuous discharge process can lead to excessively high equipment temperatures. Therefore, there is an urgent need for a solution to effectively detect the removal of the AC line and control the discharge cycle of the input filter capacitor, thereby ensuring operator safety and equipment reliability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a safety control system for a switching power supply, which can effectively detect the removal of AC lines and control the discharge cycle of the input filter capacitor, thereby ensuring operator safety and equipment reliability.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A safety control system for a switching power supply, the safety control system comprising a voltage comparison circuit, a reference voltage selection circuit, and a control circuit;

[0007] The voltage comparison circuit includes a voltage input module and a comparator. The positive input terminal of the comparator is connected to the input voltage, the negative input terminal of the comparator is connected to the output terminal of the voltage input module, and the input terminal of the voltage input module is connected to the reference voltage.

[0008] The reference voltage selection circuit includes a reversible counter module and a decoder module, with the output of the reversible counter module connected to the input of the decoder module.

[0009] The control circuit includes a positive slope detection module, a line removal detection and discharge control circuit module, and a timer module. The output terminal of the positive slope detection module is connected to the line removal detection and discharge control circuit module and the timer module. The output terminal of the timer module is connected to the line removal detection and discharge control circuit module. The output terminal of the discharge control circuit module is connected to the timer module and the positive slope detection module.

[0010] Furthermore, the reversible counter module includes a six-bit binary reversible counter module.

[0011] Furthermore, the comparator output is connected to the six-bit binary reversible counter module and the positive slope detection module.

[0012] Furthermore, the output of the decoder module is connected to the input of the control signal group of the voltage input module, and the output of the six-bit binary reversible counter module is connected to the positive slope detection module.

[0013] Furthermore, the resolution of the positive slope detection module is adjustable.

[0014] Furthermore, the reference voltage includes 64 reference voltages.

[0015] Furthermore, the decoder module includes two 3-to-8 decoder circuits.

[0016] Furthermore, the input voltage includes the sampling voltage of the active filter capacitor.

[0017] The beneficial effects of this invention are as follows:

[0018] (1) The switching power supply safety control system provided by the present invention is used for line removal detection and capacitor discharge cycle control, and consists of a voltage comparison circuit, a reference voltage selection circuit and a control circuit. The voltage comparison circuit and the reference voltage selection circuit can be modified according to the actual circuit requirements to change the reference voltage input range by modifying their corresponding reversible timer circuit and decoder circuit. It has strong portability and is easy to apply in a wide range of applications.

[0019] (2) The positive slope detection module circuit of the switching power supply safety control system provided by the present invention can be set to prevent false triggering, and can better ensure the stability of the line removal detection condition.

[0020] (3) The switching power supply safety control system provided by the present invention can effectively detect AC line voltage and realize the control of capacitor discharge cycle.

[0021] (4) The switching power supply safety control system provided by the present invention realizes the discharge that meets the standards specified by the safety agency, ensures the safety of operators, and prevents the equipment from overheating. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the switching power supply safety control system provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the state of the reversible counter module and the positive slope detection module provided in the embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the status of the line removal detection and discharge cycle control module provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the working waveform of the switching power supply safety control system provided in an embodiment of the present invention. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0027] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The commonly used resistor network discharge scheme results in significant input power loss in various modes. Using an active input filter capacitor can effectively reduce input power loss. Traditional solutions typically use capacitors to suppress power supply electromagnetic interference and do not require an external discharge resistor network. However, capacitor discharge usually requires specific conditions for activation, and the continuous discharge process can lead to excessively high equipment temperatures. Therefore, it is necessary to effectively detect the removal of AC lines and control the discharge cycle of the input filter capacitor to ensure operator safety and equipment reliability.

[0029] To address the aforementioned technical problems, the present invention provides the following embodiments of a switching power supply safety control system.

[0030] Reference Figure 1 ,like Figure 1 The diagram shown is a schematic of the safety control system for a switching power supply provided in this embodiment. This safety control system is used for line removal detection and capacitor discharge cycle control of the switching power supply. Specifically, the system includes a voltage comparison circuit, a reference voltage selection circuit, and a control circuit.

[0031] The voltage comparison circuit includes a voltage input module and a comparator COMP. The positive input terminal of the comparator is connected to the input voltage VIN, and the negative input terminal is connected to the output terminal of the voltage output module. The input terminal of the voltage input module is connected to 64 reference voltages from VREF1 to VREF64.

[0032] In one implementation, the input voltage VIN is the sampling voltage of the active filter capacitor.

[0033] The reference voltage selection circuit includes a six-bit binary reversible counter module and a decoder module; the output of the six-bit binary reversible counter module is connected to the input of the decoder module, i.e., the SEL[5:0] signal group in the figure.

[0034] In one implementation, the decoder module consists of two 3-to-8 decoder circuits.

[0035] The control circuit includes a positive slope detection module, a line removal detection and discharge cycle control circuit module, and a timer module. The p_slope signal output of the positive slope detection module is connected to the line removal detection and discharge cycle control circuit module and the timer module. The T_control signal group output of the timer module is connected to the line removal detection and discharge cycle control circuit module. The T_rst signal output of the line removal detection and discharge cycle control circuit module is connected to the timer module. The shi_sig signal is connected to the positive slope detection module.

[0036] As one implementation method, the resolution of the positive slope detection module is adjustable, and the resolution can be adjusted accordingly based on the working status, effectively reducing false triggering.

[0037] In one implementation, the comparator output signal cap_dis of the voltage comparison circuit is connected to a six-bit binary reversible counter module and a positive slope detection module.

[0038] In one implementation, the decoder module output of the reference voltage selection circuit is connected to the control signal group input of the voltage input module, and the en_slope signal output of the six-bit binary reversible counter module is connected to the positive slope detection module.

[0039] In one implementation, the line removal detection and discharge cycle control circuit module of the control circuit outputs a capacitor discharge control signal cap_control to control the capacitor to discharge.

[0040] The specific working principle of the switching power supply safety control system provided in the foregoing embodiments is as follows:

[0041] The six-bit binary reversible counter module, the positive slope detection module, the line removal detection and discharge cycle control circuit module, and the timer module each have their corresponding clock signals and a unified reset signal. After the circuit system starts working, when the reset signal is valid, the timer module is cleared, and the six-bit binary reversible counter module is set to its first initial state of 000000. Figure 4 The logic of the digital signal output corresponding to SEL[5:0]; the positive slope detection circuit is set to the initial state 000; the line removal detection and discharge cycle control circuit is set to the initial state 001, that is... Figure 4 Q[2:0] corresponds to the output digital signal logic, and at this time the corresponding module is the line removal detection cycle; after the reset signal is invalid, the circuit starts to work.

[0042] The six-bit binary reversible counter module corresponds to states from 000000 to 111111. After each state is decoded by the decoder module, the control voltage input module selects the reference voltage output for the current state from low to high and inputs it to the inverting input of the comparator. That is, the reference voltage can be switched by changing SEL[5:0]. When the input voltage VIN is greater than the reference voltage at this time, the cap_dis signal output by the comparator is high, and the six-bit binary reversible counter module increments by one when the rising edge of the clock arrives, that is, SEL[5:0] is incremented by one, and the next state is entered. After being decoded by the decoder, the control voltage input module selects a higher reference voltage and compares it with VIN at this time; conversely, when VIN is less than the reference voltage at this time, the cap_dis signal is low, the counter module decrements by one, and the corresponding voltage is selected. When the counter module enters the 111111 state, if the cap_dis signal is still high, counting is disabled, and the current state remains unchanged. The current state will only change if the cap_dis signal goes low to decrement the count, or if a reset signal is valid. The same applies to the 000000 state, which will not be elaborated further here. When the counter module is in the 000000 and 111111 states, the en_slope output is low, keeping the positive slope detection circuit in the 000 state. Correspondingly, the p_slope signal remains low, effectively reducing false triggering and ensuring the stability of its detection. Between states 000000 and 111111, the en_slope signal output is high, and the positive slope detection circuit starts working. When the cap_dis signal is high, the positive slope detection circuit sequentially enters states 001, 010, and 011 with each rising edge of the clock, setting its resolution to prevent false triggering and ensure a certain positive slope increase in the input voltage. When the circuit enters state 011, there is no need to check the cap_dis signal condition; it enters the next state 100. At this time, the p_slope signal output is high, used to set the line removal detection and discharge cycle control circuit module and clear the timer. After this state ends, the next state enters state 000, and so on. The circuit state switching is referenced... Figure 2 ,like Figure 2 The diagram shown is a state diagram of the reversible counter module and the positive slope detection module provided in this embodiment.

[0043] The timer starts counting after the reset signal becomes invalid. At this time, the line removal detection and discharge cycle control circuit is set to the initial state 001, corresponding to the line removal detection cycle. In state 001, as mentioned above, when the p_slope signal outputs a high level, the line removal detection and discharge cycle control circuit module briefly enters state 000 and resets the timer to zero, restarting the counting process. Subsequently, it returns to state 001 when the next clock edge arrives. Figure 3 ,like Figure 3 The diagram shown is a status diagram of the line removal detection and discharge cycle control module provided in this embodiment.

[0044] After the AC line is removed, the p_slope signal output remains low, and the timer is no longer reset. When the timer reaches T_rem, refer to... Figure 4 ,like Figure 4 The diagram shown is a schematic of the working waveforms of the switching power supply safety control system provided in this embodiment. The T_rem time can be set in the timer module, typically 100ms, indicating that the line removal condition has been confirmed. At this time, the capacitor discharge cycle begins. The line removal detection and discharge cycle control circuit module first enters state 101, i.e., the capacitor discharge cycle, as shown... Figure 3 As shown; simultaneously, the T_rst signal outputs a high level for one clock cycle to clear the timer, and the timer restarts counting; during the capacitor discharge cycle, the shi_sig signal outputs a high level, keeping the positive slope detection circuit in the 000 state and keeping the p_slope signal at a low level, thus ensuring that the current cycle is completed. The corresponding cap_contol signal is then output to the control module to perform the corresponding operation to discharge the capacitor, and the corresponding input voltage sampling signal VIN also decreases.

[0045] When the line removal detection and discharge cycle control circuit module is in state 101, after the timer reaches T_dis (which can be set in the timer module, typically 30ms), it indicates that one capacitor discharge cycle is complete. At this point, it enters state 010, stopping the capacitor discharge to limit the discharge phase and prevent overheating. In state 010, if the circuit is reconnected to the AC line and voltage is applied, the positive slope detection module will detect the positive slope again. When p_slope is high, the next state is 001, and the timer is reset. If no voltage is reapplied, p_slope remains low. After the timer reaches T_det (which can be set in the timer module, typically 30ms), the circuit returns to state 101, initiating the capacitor discharge cycle. This cycle continues until the capacitor is discharged to a safe level.

[0046] The switching power supply safety control system provided in this embodiment consists of a voltage comparison circuit, a reference voltage selection circuit, and a control circuit. The voltage comparison circuit and the reference voltage selection circuit can be modified according to actual circuit requirements, altering their corresponding reversible timer circuit and decoder circuit to change the reference voltage input range. This design offers strong portability and ease of widespread application. The positive slope detection module circuit of this safety control system allows for resolution settings to prevent false triggering, better ensuring the stability of line removal detection conditions. This safety control system effectively detects AC line voltage and controls the capacitor discharge cycle. It achieves discharge that meets the standards specified by safety authorities, ensuring operator safety and preventing equipment overheating.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A safety control system for a switching power supply, characterized in that, The safety control system includes a voltage comparison circuit, a reference voltage selection circuit, and a control circuit. The voltage comparison circuit includes a voltage input module and a comparator. The positive input terminal of the comparator is connected to the input voltage, the negative input terminal of the comparator is connected to the output terminal of the voltage input module, and the input terminal of the voltage input module is connected to the reference voltage. The reference voltage selection circuit includes a reversible counter module and a decoder module, with the output of the reversible counter module connected to the input of the decoder module. The control circuit includes a positive slope detection module, a line removal detection and discharge control circuit module, and a timer module. The output terminal of the positive slope detection module is connected to the line removal detection and discharge control circuit module and the timer module. The output terminal of the timer module is connected to the line removal detection and discharge control circuit module. The output terminal of the discharge control circuit module is connected to the timer module and the positive slope detection module. When the line removal detection and discharge control circuit module is in state 101, when the timer reaches T_dis, it indicates that a capacitor discharge cycle is complete. At this time, it enters state 010 to stop the capacitor discharge and limit the discharge phase time. In state 010, if the circuit is reconnected to the AC line and voltage is applied, the positive slope detection module will detect the positive slope again. When p_slope is high, the next state enters 001, and the timer is reset to zero. If no voltage is reapplied, p_slope remains low. When the timer reaches T_det, the circuit enters state 101 again, which is the capacitor discharge cycle. This cycle continues until the capacitor is discharged to a safe level.

2. The switching power supply safety control system as described in claim 1, characterized in that, The reversible counter module includes a six-bit binary reversible counter module.

3. The switching power supply safety control system as described in claim 2, characterized in that, The comparator output is connected to the six-bit binary reversible counter module and the positive slope detection module.

4. The switching power supply safety control system as described in claim 2, characterized in that, The output of the decoder module is connected to the input of the control signal group of the voltage input module, and the output of the six-bit binary reversible counter module is connected to the positive slope detection module.

5. The switching power supply safety control system as described in claim 1, characterized in that, The resolution of the positive slope detection module is adjustable.

6. The switching power supply safety control system as described in claim 1, characterized in that, The reference voltages include 64 reference voltages.

7. The switching power supply safety control system as described in claim 1, characterized in that, The decoder module includes two 3-to-8 decoder circuits.

8. The switching power supply safety control system as described in claim 1, characterized in that, The input voltage includes the sampling voltage of the active filter capacitor.

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