Fault detection device for soft start circuit

Abstract

The invention particularly relates to a fault detection device for a soft start circuit. The device comprises a control circuit module and a soft start fault diagnosis module. The control circuit module is electrically connected with the control end of the switch part; the soft start fault diagnosis module comprises a pre-stage voltage detection unit, a post-stage voltage detection unit and a timing judgment unit; the pre-stage voltage detection unit is connected with the power supply input end; the post-stage voltage detection unit is connected with the capacitor bank; the timing judgment unit is electrically connected with the pre-stage voltage detection unit, the post-stage voltage detection unit and the control circuit module respectively; the processor is used for judging whether the soft start circuit has faults according to timing results and generating fault information. According to the device, fault diagnosis can be converted from passive lagging to active early warning at the initial stage of power-on, and potential faults can be recognized in advance; and different fault types can be accurately distinguished, and the technical defect that a fault source cannot be positioned in a traditional scheme is overcome.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically to a fault detection device for a soft-start circuit. Background Technology

[0002] In high-end applications such as motor drives, precision power supplies, and server hot-swappable devices, the reliability of soft-start circuits is one of the most critical design requirements. As the first line of defense for the system upon power-up, this circuit's core function is to smoothly suppress surge currents, protecting downstream precision capacitors, power devices, and sensitive loads. If the soft-start circuit itself has a latent fault (such as an open-circuit starting resistor or a stuck switching device) that goes undetected by the system, it will not only lose its protective function but also become a fatal failure point—for example, causing subsequent circuits to experience a full-voltage surge upon the next power-up, leading to permanent damage to expensive core components and economic losses far exceeding the cost of the soft-start circuit itself.

[0003] Existing soft-start circuit protection schemes are typically short-circuit fuse schemes based on PTC thermistors. The core of these schemes is the use of a positive temperature coefficient thermistor as a current-limiting resistor. The working principle of this scheme relies entirely on the physical characteristics of the PTC: at room temperature, the PTC exhibits low resistance, allowing current to flow; when the current flowing through it exceeds a certain threshold or when it heats up due to a fault, its temperature rises sharply, causing its resistance to increase exponentially (i.e., a "jump"), thus exerting a strong current-limiting effect on the circuit, manifesting as a "shutdown" state. This scheme can be applied to most soft-start circuit protection scenarios and has a certain level of protection effectiveness.

[0004] However, when used in high-precision, high-value electronic equipment, the above-mentioned solution has significant drawbacks, potentially leading to substantial losses in equipment value. As can be seen, the PTC solution is essentially a passive, reactive protection mechanism based on thermal accumulation. It only cuts off the circuit by increasing the temperature and resistance of the resistor after the fault current has occurred and persisted for a period of time. This delayed response means that between the failure of the soft-start circuit and the PTC's activation, irreversible damage to the precision load may have already occurred. More seriously, this solution can only indicate that "protection has been triggered," but it cannot distinguish whether the root cause of the fault is a failure of the starting resistor or a failure of the switching transistor. This poses a significant obstacle to rapid recovery and accurate repair, greatly increasing the downtime risk and maintenance costs of high-precision systems. Summary of the Invention

[0005] The purpose of this invention is to provide a fault detection device for soft-start circuits. This device can transform fault diagnosis from passive and delayed to active early warning at the initial power-on stage, realizing early identification of potential faults. It can also accurately distinguish different fault types, solving the technical defects of traditional solutions that cannot locate the root cause of faults.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a fault detection device for a soft-start circuit, the soft-start circuit including a starting resistor, a switch in parallel with the starting resistor, and a capacitor bank in parallel with the load; the fault detection device for the soft-start circuit includes a control circuit module and a soft-start fault diagnosis module.

[0008] The control circuit module is electrically connected to the control terminal of the switch unit and is used to transmit a soft-start control signal to drive the switch unit to perform a conduction / turn-off action.

[0009] The soft-start fault diagnosis module includes a front-end voltage detection unit, a rear-end voltage detection unit, and a timing judgment unit.

[0010] The front-stage voltage detection unit is connected to the power input terminal and is used to detect the front-stage voltage;

[0011] The downstream voltage detection unit is connected to the capacitor bank and is used to detect the downstream voltage.

[0012] The timing judgment unit is electrically connected to the front-stage voltage detection unit, the rear-stage voltage detection unit, and the control circuit module, respectively; it is used to determine whether there is a fault in the soft-start circuit based on the timing result and generate fault information.

[0013] As a preferred embodiment of the present invention, the timing judgment unit includes a timing section, which is used to start timing when the downstream voltage is less than the discrimination voltage value, and to generate start-up resistor fault information when the timing duration exceeds the diagnostic time.

[0014] As a preferred embodiment of the present invention, the timing judgment unit is used to detect damage to the starting resistor; when the preceding voltage is within a preset operating voltage range, the timing judgment unit receives the following voltage and determines whether the following voltage reaches a preset first discrimination voltage value within a preset first diagnostic time. If it does not reach the first discrimination voltage value, the timing judgment unit determines that the starting resistor of the soft-start circuit is in a damaged state and generates corresponding starting resistor fault information; if it reaches the first discrimination voltage value, no action is taken.

[0015] As a preferred embodiment of the present invention, the timing judgment unit is used to detect damage to the switching unit; when the front-stage voltage is within a preset operating voltage range, the timing judgment unit receives the rear-stage voltage; when the rear-stage voltage is charged through the starting resistor to reach a preset first discrimination voltage value, the timing judgment unit sends a soft-start control signal to the control circuit module to control the switching unit to conduct, and monitors the rise of the rear-stage voltage after conduction;

[0016] If the subsequent voltage does not reach the preset second discrimination voltage value within the preset second diagnostic time, it is determined that the switch cannot close normally, and a corresponding switch fault information is generated; if it does reach the value, no action is taken. Preferably, the second discrimination voltage value tracks the preceding voltage in real time, and the result of the second discrimination voltage value is the same as the preceding voltage.

[0017] As a preferred embodiment of the present invention, the second discrimination voltage value tracks the preceding stage voltage in real time, and the result of the second discrimination voltage value is the difference between the preceding stage voltage and the voltage drop threshold.

[0018] As a preferred embodiment of the present invention, the voltage drop threshold value ranges from an integer percentage of the preceding voltage.

[0019] As a preferred embodiment of the present invention, the voltage drop threshold is 1V.

[0020] As a preferred embodiment of the present invention, the fault detection device for the soft-start circuit further includes a fault warning module, which is connected to the soft-start fault diagnosis module and is used to receive the fault information and automatically execute an alarm action.

[0021] As a preferred embodiment of the present invention, the fault detection device for the soft-start circuit further includes a display module, which is connected to the soft-start fault diagnosis module and the fault warning module, and is used to visually display the fault information and the currently executed alarm action.

[0022] In summary, the present invention has the following beneficial effects:

[0023] This invention transforms fault diagnosis from traditional passive, post-event protection to proactive, pre-event early warning at the initial power-on stage through the coordinated operation of voltage detection and timing judgment in the front and rear stages. It can accurately identify potential faults before they cause substantial damage. This device can not only detect the occurrence of faults, but also accurately locate the root cause of the fault, whether it is an open circuit in the starting resistor or a failure of the switching component to conduct. This enables intelligent monitoring of the health status of the soft-start circuit, significantly improves the reliability of high-value electronic equipment, and greatly reduces the downtime risk and maintenance costs caused by latent faults. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a detailed structural block diagram of the device;

[0026] Figure 2 This is a circuit diagram of a specific fault detection device in the embodiment;

[0027] Figure 3 This is a voltage diagram illustrating a specific soft-start control method in the embodiment. Detailed Implementation

[0028] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed merely to enable those skilled in the art to better understand and implement the subject matter described herein, and are not intended to limit the scope, applicability, or examples set forth in the claims. The function and arrangement of the elements discussed may be changed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the various examples. For example, the described methods may be performed in a different order than described, and steps may be added, omitted, or combined. Furthermore, features described in some examples may be combined in other examples.

[0029] As used herein, the term "comprising" and its variations are open terms meaning "including but not limited to". The term "based on" means "at least partially based on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other definitions, whether explicit or implicit, may be included below. Unless explicitly indicated by the context, the definition of a term shall remain consistent throughout the specification.

[0030] like Figure 1As shown, this embodiment provides a fault detection device for a soft-start circuit. The soft-start circuit includes a starting resistor, a switch connected in parallel with the starting resistor, and a capacitor bank connected in parallel with the load. The fault detection device also includes a control circuit module and a soft-start fault diagnosis module. The control circuit module is electrically connected to the control terminal of the switch and is used to transmit a soft-start control signal to drive the switch to perform on / off actions. The soft-start fault diagnosis module includes a front-stage voltage detection unit, a rear-stage voltage detection unit, and a timing judgment unit. The front-stage voltage detection unit is connected to the power input terminal and is used to detect the front-stage voltage. The rear-stage voltage detection unit is connected to the capacitor bank and is used to detect the rear-stage voltage. The timing judgment unit is electrically connected to the front-stage voltage detection unit, the rear-stage voltage detection unit, and the control circuit module, respectively.

[0031] The soft-start fault diagnosis module can be implemented by a microcontroller unit (MCU). The front-end voltage detection module and the back-end voltage detection module can be implemented based on the ADC analog-to-digital converter inside the MCU. The timing judgment unit can be implemented based on the processor running a preset program in the MCU.

[0032] More specifically, combined Figure 2 As shown, this embodiment provides a specific fault detection device circuit, wherein the soft-start circuit includes a starting resistor R1, a switch Q1 connected in parallel with the starting resistor R1, and a capacitor bank connected in parallel with the load. The capacitor bank consists of three capacitors C1, C2, and C3 connected in parallel. This fault detection device for the soft-start circuit also includes a control circuit module and a soft-start fault diagnosis module, wherein P+ and P- are power supply voltages. The control circuit module is electrically connected to the control terminal of the switch Q1 and is used to transmit a soft-start control signal DO1 to drive the switch Q1 to perform a conduction / turn-off action. The soft-start fault diagnosis module can detect the power supply voltage at P+ and P-, i.e., the front-end voltage V1; it can also detect the voltage across the capacitor bank, i.e., the rear-end voltage V2.

[0033] During normal soft-start, the switch Q1 is in the off state by default. When P+ and P- are connected to the power supply, the power supply will charge capacitors C1, C2, and C3 through the starting resistor R1. Figure 3 It can be seen that at this time, the waveform of the subsequent voltage V2 is the OA segment curve (relatively slow rise); when the voltage of the subsequent voltage V2 is greater than or equal to the voltage at point A (the first discrimination voltage value Va), the control circuit module transmits the soft start control signal DO1 based on the normal preset instruction, and the control switch Q1 is opened. At this time, the circuit impedance decreases, and the subsequent voltage V2 will rise rapidly. The voltage waveform is shown as segment AB. After full start-up, the voltage of the subsequent voltage V2 remains consistent with the voltage of the preceding voltage V1.

[0034] Specifically, the soft-start fault diagnosis module, relying on its timing judgment unit, can perform the following two types of fault detection:

[0035] (1) Based on the above normal soft start process, the starting resistor R1 is tested for damage.

[0036] If the starting resistor R1 fails, the voltage of the subsequent stage V2 will remain at 0V, while the voltage of the preceding stage V1 will remain consistent with the voltages P+ and P- (which can be considered as the preceding stage voltage V1 being within the preset operating voltage range).

[0037] Furthermore, when the current stage voltage V1 is within the preset operating voltage range, it means that the power supply terminals P+ and P- are powered normally. The timing judgment unit receives the subsequent stage voltage V2 and determines whether the subsequent stage voltage V2 reaches the preset first discrimination voltage value Va (point A in the figure) within the preset first diagnostic time T1. It is known that when the starting resistor R1 is damaged, the voltage of the subsequent stage voltage V2 will always remain at 0 volts, that is, the subsequent stage voltage V2 will definitely not reach the preset first discrimination voltage value Va. At this time, the timing judgment unit will determine that the starting resistor R1 is damaged and generate corresponding fault information for the starting resistor R1. If the value is reached, no action will be taken.

[0038] (2) Based on the above normal soft start process, damage detection is performed on the switch Q1.

[0039] When the switch Q1 is damaged (i.e. cannot be closed), the subsequent voltage V2 will rise at a relatively slow rate throughout the entire process (i.e., the voltage rise rate of segment AB is also slow). Since the switch Q1 cannot conduct, the problem of the switch Q1 not conducting can be determined by timing the voltage rise time of segment AB.

[0040] Furthermore, when the current stage voltage V1 is within the preset operating voltage range, it means that the power supply terminals P+ and P- are powered normally. The timing judgment unit receives the subsequent stage voltage V2 and determines whether the subsequent stage voltage V2 reaches the preset first discrimination voltage value Va within the preset first diagnostic time T1. When the subsequent stage voltage V2 is charged through the starting resistor R1 to reach the preset first discrimination voltage value Va, the timing judgment unit sends a soft start control signal DO1 to the control circuit module to control the switch Q1 to conduct and monitors the rise of the subsequent stage voltage V2 after conduction.

[0041] If the downstream voltage V2 does not reach the preset second discrimination voltage value Vb (point B in the figure) within the preset second diagnostic time T2, it is determined that the switch Q1 cannot close normally, and a fault information for the switch Q1 is generated accordingly; if it does reach the value, it will not operate.

[0042] As can be seen from the above, if the switch Q1 is not damaged and can close normally, the subsequent voltage V2 can reach the preset second discrimination voltage value Vb within the preset second diagnostic time T2. This is because the second diagnostic time T2 can be accurately adjusted and set according to the actual equipment.

[0043] In another possible embodiment, the second discrimination voltage value Vb tracks the value of the preceding stage voltage V1 in real time, and the result of the second discrimination voltage value Vb is the same as the value of the preceding stage voltage V1. This is determined by the circuit operating characteristics. Even if the switch Q1 is damaged, it will not affect the final voltage value of the subsequent stage voltage V2 after stabilization. Therefore, the second discrimination voltage value Vb can directly track the value of the preceding stage voltage V1, thereby eliminating the need for manual preset operation.

[0044] In another possible embodiment, the second discrimination voltage value Vb tracks the preceding voltage V1 value in real time, and the result of the second discrimination voltage value is the difference between the preceding voltage V1 value and the voltage drop threshold Vs.

[0045] To prevent errors in the sampling of the preceding voltage V1 and the following voltage V2, and to prevent the voltage drop of the switching section Q1 from causing V1≠V2, a voltage drop threshold Vs is set so that Vb=V1-Vs.

[0046] In another possible embodiment, the voltage drop threshold Vs can be a fixed value, such as 1V; or it can be an integer percentage of the preceding voltage V1.

[0047] To further enhance practicality, this fault detection device for soft-start circuits also includes a fault warning module, which is connected to the soft-start fault diagnosis module. The fault warning module is used to receive fault information and automatically execute alarm actions, such as audible and visual alarms.

[0048] To further enhance practicality, this fault detection device for soft-start circuits also includes a display module, which is connected to the soft-start fault diagnosis module and the fault warning module. The display module is used to visually display fault information and currently executed alarm actions; for example, the fault code indicates the specific fault type (damaged starting resistor R1 or faulty switch Q1), thereby enabling rapid location of hardware faults and improving system safety.

[0049] In summary, the above embodiments, by performing voltage detection and timeout judgment on key components of the soft-start circuit before equipment operation, achieve early fault diagnosis and precise location, effectively avoiding unexpected shutdowns and greater losses caused by soft-start circuit failures during operation.

[0050] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

Claims

1. A fault detection device for a soft-start circuit, the soft-start circuit comprising a starting resistor, a switching section connected in parallel with the starting resistor, and a capacitor bank connected in parallel with the load; characterized in that, This fault detection device for soft-start circuits includes a control circuit module and a soft-start fault diagnosis module; The control circuit module is electrically connected to the control terminal of the switch unit and is used to transmit a soft-start control signal to drive the switch unit to perform a conduction / turn-off action. The soft-start fault diagnosis module includes a front-end voltage detection unit, a rear-end voltage detection unit, and a timing judgment unit. The front-stage voltage detection unit is connected to the power input terminal and is used to detect the front-stage voltage; The downstream voltage detection unit is connected to the capacitor bank and is used to detect the downstream voltage. The timing judgment unit is electrically connected to the front-stage voltage detection unit, the rear-stage voltage detection unit, and the control circuit module, respectively; it is used to determine whether there is a fault in the soft-start circuit based on the timing result and generate fault information.

2. The fault detection device for a soft-start circuit according to claim 1, characterized in that, The timing judgment unit includes a timing section, which is used to start timing when the downstream voltage is less than the discrimination voltage value, and to generate start-up resistor fault information when the timing duration exceeds the diagnostic time.

3. The fault detection device for a soft-start circuit according to claim 1, characterized in that, The timing judgment unit is used to detect damage to the starting resistor; When the preceding voltage is within a preset operating voltage range, the timing judgment unit receives the following voltage and determines whether the following voltage reaches a preset first discrimination voltage value within a preset first diagnostic time. If it does not reach the first discrimination voltage value, the timing judgment unit determines that the starting resistor of the soft-start circuit is damaged and generates corresponding starting resistor fault information. If it does reach the first discrimination voltage value, no action is taken.

4. A fault detection device for a soft-start circuit according to claim 1, characterized in that, The timing judgment unit is used to detect damage to the switch part; When the preceding voltage is within a preset operating voltage range, the timing and judgment unit receives the following voltage. When the subsequent voltage is charged through the starting resistor to reach the preset first discrimination voltage value, the timing judgment unit sends a soft start control signal to the control circuit module to control the switch to turn on, and monitors the rise of the subsequent voltage after it is turned on. If the downstream voltage does not reach the preset second discrimination voltage value within the preset second diagnostic time, it is determined that the switch cannot close normally, and corresponding switch fault information is generated. If the condition is met, no action is taken.

5. A fault detection device for a soft-start circuit according to claim 4, characterized in that, The second discrimination voltage value tracks the preceding voltage in real time, and the result of the second discrimination voltage value is the same as that of the preceding voltage.

6. A fault detection device for a soft-start circuit according to claim 4, characterized in that, The second discrimination voltage value tracks the preceding stage voltage in real time, and the result of the second discrimination voltage value is the difference between the preceding stage voltage and the voltage drop threshold.

7. A fault detection device for a soft-start circuit according to claim 6, characterized in that, The voltage drop threshold is determined as an integer percentage of the preceding voltage.

8. A fault detection device for a soft-start circuit according to claim 6, characterized in that, The voltage drop threshold value is 1V.

9. A fault detection device for a soft-start circuit according to claim 1, characterized in that, The fault detection device for soft-start circuits also includes a fault warning module, which is connected to the soft-start fault diagnosis module and is used to receive the fault information and automatically execute alarm actions.

10. A fault detection device for a soft-start circuit according to claim 9, characterized in that, The fault detection device for soft-start circuits also includes a display module, which is connected to the soft-start fault diagnosis module and the fault warning module, and is used to visually display the fault information and the currently executed alarm action.

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