A file system protection system based on a delay power-off circuit

Abstract

The application relates to a file system protection system based on a time-delay power-off circuit, which comprises a power module connected with an external power input and used for supplying power to a vehicle fault prediction and health management system when the external power is normal, and also electrically connected with a super capacitor to charge the super capacitor; the super capacitor is used for discharging to supply power to the vehicle fault prediction and health management system when there is no external power input; a dynamic power-off detection module is electrically connected with the power module and the super capacitor; the dynamic power-off detection module dynamically adjusts a voltage threshold value for judging power-off according to a super capacitor discharging current, and judges that the external power is powered off when the dynamic power-off detection module detects that the voltage is smaller than the threshold value. The application excludes abnormal power-off triggering caused by external interference, can use the discharging time of the super capacitor for as long as possible to complete file system management, and can judge the damage or performance decline of the capacitor according to the discharging condition, so that the components can be replaced in time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle communication, and particularly relates to a file system protection system based on a delay power-off circuit. BACKGROUND

[0002] In the prior art, in order to prevent abnormal power-off of equipment, resulting in incomplete data writing and file system damage, a delay power-off circuit is designed in a rail transit vehicle fault prediction and health management system based on edge computing technology. Figure 1 As shown in the figure, when an external power supply is input, the power supply module works normally, and supplies power to the rail transit vehicle fault prediction and health management system through BAT2, and the system works normally; at the same time, the voltage module charges the super capacitor, and the power-off feedback signal is invalid.

[0003] When there is no input of the external power supply, the super capacitor discharges, supplies power to the system through BAT1, and the power-off feedback signal is valid. When the system detects the power-off feedback signal, the existing file system operation is completed within the super capacitor power supply time, and the file system is unloaded, thereby preventing file system damage.

[0004] The design has the following defects in actual use:

[0005] 1. Interference causes abnormal power-off feedback signal, and misfires power-off management;

[0006] 2. When the super capacitor is damaged or performance is degraded, the power storage cannot meet the fixed time length of file system management. SUMMARY

[0007] The technical problem to be solved by the application is to solve the above defects in the prior art, and to provide a file system protection system based on a delay power-off circuit.

[0008] The technical solution adopted by the application to solve the technical problem is:

[0009] A file system protection system based on a delay power-off circuit, comprising:

[0010] a power supply module connected to an external power supply input and supplying power to a rail transit vehicle fault prediction and health management system when the external power supply is normal, and electrically connected to a super capacitor to charge the super capacitor;

[0011] a super capacitor for discharging to supply power to the rail transit vehicle fault prediction and health management system when there is no input of the external power supply;

[0012] The dynamic power-off detection module is electrically connected with the power module and the super capacitor, and dynamically adjusts a voltage threshold for judging power-off according to a super capacitor discharge current condition; when the dynamic power-off detection module detects that the voltage is less than the threshold, it is judged that the external power supply is powered off.

[0013] The vehicle fault prediction and health management system is connected with the dynamic power-off detection module, and when the dynamic power-off detection module judges that the external power supply is powered off, the vehicle fault prediction and health management system continues to execute the reading and writing currently being processed by the file system, and no new reading and writing task is established.

[0014] Preferably, the file system protection system based on the time-delay power-off circuit of the present application synchronously samples the super capacitor discharge current and voltage through a high-precision ADC during super capacitor discharge, calculates the total charge amount discharged to the load during super capacitor discharge through the integration of the discharge time by the current, and calculates the actual capacity of the super capacitor through the measurement of the voltage difference of the super capacitor, and saves the capacity parameter in the non-volatile memory of the vehicle fault prediction and health management system.

[0015] Preferably, the file system protection system based on the time-delay power-off circuit of the present application further comprises a capacitor charging control module for controlling the charging termination voltage U MAX .

[0016] Preferably, the file system protection system based on the time-delay power-off circuit of the present application, the charging termination voltage U MAX is calculated through the following relationship:

[0017]

[0018] wherein the capacitance of the capacitor is C, the capacitance C is obtained by measurement, the capacitor charging termination voltage is U MAX , the discharge cutoff voltage is U MIN , and U MIN is determined by the minimum supply voltage of the device, and W is the energy required during file system protection obtained through testing.

[0019] Preferably, the file system protection system based on the time-delay power-off circuit of the present application maintains the super capacitor when U MAX is less than or equal to U MIN .

[0020] Preferably, the file system protection system based on the time-delay power-off circuit of the application, the capacitor charging control module comprises a DC / DC controller with CI / CV function, an input of an external DC power supply of 12V-24V, and is used for controlling charging of the super capacitor, and is in a constant current control mode when the charging of the super capacitor does not reach a limit value, and stops charging after reaching a set voltage.

[0021] Preferably, the file system protection system based on the time-delay power-off circuit of the application, the capacitor charging control module further comprises:

[0022] A first operational amplifier, an input of a DAC output signal of the single-chip microcomputer, and an output connected to a voltage feedback pin of the DC / DC controller through a voltage dividing resistor, and the output voltage of the DAC is adjusted by the single-chip microcomputer to dynamically adjust the output voltage of the DC / DC controller, so as to adjust the charging termination voltage of the super capacitor;

[0023] A second operational amplifier, a voltage of the super capacitor is divided by a second resistor and a third resistor, and then is buffered by the second operational amplifier and connected to an ADC second channel of the single-chip microcomputer, and the capacitor voltage is obtained by AD conversion;

[0024] A precision instrument amplifier, an input signal is a voltage on a sampling resistor of the super capacitor discharging circuit, the amplifier gain is set by a fourth resistor, and the voltage is connected to an ADC first channel of the single-chip microcomputer after being amplified to a certain multiple, and the circuit current value is obtained by AD conversion;

[0025] The ADC of the single-chip microcomputer is set to a synchronous sampling mode to ensure synchronous sampling of the voltage and the current.

[0026] Preferably, the file system protection system based on the time-delay power-off circuit of the application, the relationship between the output voltage of the DC / DC controller and the DAC voltage is as follows:

[0027]

[0028] In the formula, V DAC is the output voltage of the No. 4 pin of the first operational amplifier, V FB is the feedback reference voltage of the DC / DC controller, V OUT is the set output voltage of the DC / DC controller, R 485 is the resistance value of the resistor R485, R 422 is the resistance value of the resistor R422, R 423 is the resistance value of the resistor R423.

[0029] The file system protection system based on the time-delay power-off circuit of the application has the following beneficial effects:

[0030] The design removes the power-down feedback signal, adopts the detection voltage and current method, and excludes the abnormal power-down trigger caused by external interference; the current and voltage detection method is not easy to be affected by external interference.

[0031] According to the super capacitor discharge current condition, the voltage threshold for judging power-down is dynamically adjusted, when the voltage is less than the threshold, it is judged that the external power supply is powered down; this way can use the discharge time of super capacitor as long as possible to complete the management of file system.

[0032] According to the discharge condition, the damage or performance decline of the capacitor is judged, so as to replace the parts in time. BRIEF DESCRIPTION OF DRAWINGS

[0033] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0034] Figure 1 is a schematic diagram of a vehicle fault prediction and health management system delay power-off circuit structure in the prior art;

[0035] Figure 2 is a schematic diagram of a file system protection system structure based on a delay power-off circuit of the embodiment of the present application;

[0036] Figure 3 is a super capacitor charging management and voltage and current sampling and dynamic voltage regulation circuit diagram of the embodiment of the present application.

[0037] The reference numerals in the drawings are:

[0038] U5 DC / DC controller;

[0039] U55 A first operational amplifier;

[0040] U57 A second operational amplifier;

[0041] U56 precision instrument amplifier;

[0042] R485 voltage dividing resistor;

[0043] R487 second resistor;

[0044] R488 third resistor;

[0045] R421 sampling resistor;

[0046] R486 fourth resistor. DETAILED DESCRIPTION

[0047] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0048] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0049] In the description of the present application, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0050] The technical solutions of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0051] Embodiment

[0052] The embodiment provides a file system protection system based on a delay power-off circuit, characterized by comprising:

[0053] A power module is connected to an external power input and supplies power to the vehicle fault prediction and health management system when the external power is normal, and is electrically connected with a super capacitor to charge the super capacitor;

[0054] The super capacitor is used to discharge to supply power to the vehicle fault prediction and health management system when there is no input from the external power supply;

[0055] A dynamic power-off detection module is electrically connected with the power module and the super capacitor; the dynamic power-off detection module dynamically adjusts the voltage threshold for judging power-off according to the super capacitor discharge current, and judges that the external power supply is powered off when the dynamic power-off detection module detects that the voltage is less than the threshold;

[0056] A vehicle fault prediction and health management system is connected with the dynamic power-off detection module, when the dynamic power-off detection module judges that the external power supply is powered off, the vehicle fault prediction and health management system continues to execute the reading and writing currently being processed by the file system, and no new reading and writing task is established.

[0057] The dynamic power-off detection design is as shown in Figure 2

[0058] The design removes the power-off feedback signal, adopts a detection voltage and current method, and excludes abnormal power-off triggers caused by external interference. The current and voltage detection method is not easily affected by external interference.

[0059] Reliable judgment of power supply state

[0060] According to the super capacitor charging and discharging current and the device power consumption, the voltage threshold for judging power-off is dynamically adjusted. When the voltage is less than the threshold, it is judged that the external power supply is powered on, and when the voltage is greater than the threshold, it is judged that the capacitor is discharging, i.e. the external power supply is powered off. This judgment method is not easily affected by the residual voltage of the power line and other devices supplied by the same power supply.

[0061] Accurate measurement of capacitor capacity

[0062] During the discharge of the super capacitor, the discharge current and voltage of the capacitor are synchronously sampled by a high-precision ADC. The total charge discharged to the load during the discharge of the capacitor can be calculated by integrating the current with respect to the discharge time. At the same time, the actual capacity of the super capacitor can be calculated by measuring the voltage difference of the capacitor. The capacity parameter is saved in the non-volatile memory of the system. This capacitor calculation method takes into account the manufacturing error of 10% to 20% during the manufacturing process of the capacitor and the reduction of the capacitor value after long-term use, and is more accurate.

[0063] Dynamic adjustment of capacitor charging voltage

[0064] The power and time consumed by the device during data saving and normal shutdown after power-off are not much changed. Through multiple experiments, it can be measured that in actual use, considering a certain derating, i.e. the energy provided by the capacitor during the file system power-off protection period reaches the value after the derating, the file system can be protected.

[0065] When the working voltage of the super capacitor increases, the capacity value of the capacitor decreases sharply. The shorter the service life of the capacitor, the longer the service life, so the service life of the capacitor can be improved by reducing the working voltage of the capacitor.

[0066] The capacity of the capacitor is C, the termination voltage of the capacitor is U MAX , the discharge cutoff voltage is U MIN , and U MIN ​The minimum supply voltage of the device determines a certain value. W is the energy required by the device file system protection device obtained through testing. The discharge energy of the capacitor and the energy required by the device are related as follows.

[0067]

[0068] When the system life is in the early stage, the capacitance C of the super capacitor is large, and a lower charging cutoff voltage U can be calculated by the above formula MAX The lower cutoff voltage in the early stage can effectively delay the aging speed of the super capacitor. After the device works for a certain period of time, the capacitance C of the super capacitor decreases, and the charging cutoff voltage of the capacitor is gradually increased by the determined value of the super capacitor obtained by measurement. This charging method can maximize the service life of the capacitor, that is, the service life of the device, and maintain the device when the capacitance value decays to the minimum limit, which can prolong the maintenance period of the device.

[0069] Figure 3 The charging management and voltage and current sampling and dynamic voltage regulation circuit of the super capacitor.

[0070] U5 is a DC / DC controller with CI / CV function, the input is an external DC power supply of 12V to 24V, and the output of pin SW is filtered through inductance L5 and capacitance C108 to output a stable DC power supply. In the figure, C102, C103, C104 and C105 are super capacitors, and the four capacitors are connected in series mode to form a super capacitor group. The output of the DC / DC controller U5 is connected to the input end of the super capacitor group to charge the super capacitor. The DC / DC output voltage is in constant current control mode when the super capacitor charging does not reach the limit value, and stops charging and turns to constant voltage mode after charging to the set voltage.

[0071] U55A is a first operational amplifier, the input is the DAC output signal of the single-chip microcomputer, and the output is connected to the voltage feedback pin 1 of the DC / DC controller U5 through the voltage dividing resistor R485. The relationship between the output voltage of the DC / DC controller U5 and the DAC output voltage is:

[0072]

[0073] In the formula, V DAC is the output voltage of pin 4 of the first operational amplifier U55A. Because the first operational amplifier U55A is configured in voltage follower mode, its output voltage V DAC is equal to the DAC output voltage of the single-chip microcomputer. V OUT is the set output voltage of the DC / DC controller U5. V FB is the feedback reference voltage of the DC / DC controller U5, which is a fixed parameter of the DC / DC chip and is 0.8V.

[0074] The component parameters R485=10K, R422=100K, R423=10K, V FB =0.8V are substituted into the circuit, and after adjusting the order of the equations, we get:

[0075] V OUT =10(1.6-V DAC )+0.8

[0076] Therefore, by adjusting the output voltage of the DAC through the single-chip microcomputer, the output voltage of the DC / DC controller U5 can be dynamically adjusted, thereby adjusting the charging cutoff voltage of the super capacitor.

[0077] U57A is a second operational amplifier, and the super capacitor voltage is divided by resistors R487 and R488 and then connected to the input pin 1 of the second operational amplifier U57A. The output pin 4 is connected to the ADC channel 2 of the single-chip microcomputer. The second operational amplifier U57A functions to drive the sampling capacitor of the ADC channel of the single-chip microcomputer. The single-chip microcomputer obtains the voltage of the super capacitor through AD conversion.

[0078] U56 is a precision instrument amplifier, which functions to amplify weak signals and drive the sampling capacitor of the ADC channel of the single-chip microcomputer. The input signal is the voltage on the sampling resistor R421 of the super capacitor discharge circuit. The amplifier gain is set to 10 times through R486, and then connected to the ADC channel 1 of the single-chip microcomputer. The circuit current value is obtained through AD conversion.

[0079] The ADC of the single-chip microcomputer is set to synchronous sampling mode, which can ensure synchronous sampling of voltage and current.

[0080] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical concept of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined by the scope of the claims.

Claims

1. A file system protection system based on a time delay power-off circuit, characterized by, include: The power module is connected to an external power input and supplies power to the vehicle fault prediction and health management system when the external power is normal. It is also electrically connected to a supercapacitor to charge the supercapacitor. Supercapacitors are used to discharge when there is no external power input to power the vehicle fault prediction and health management system. A dynamic power failure detection module is electrically connected to the power module and the supercapacitor. The dynamic power failure detection module determines the dynamically adjusted voltage threshold for power failure based on the discharge current of the supercapacitor. When the dynamic power failure detection module detects that the voltage is less than the threshold, it determines that the external power supply has failed. The vehicle fault prediction and health management system is connected to the dynamic power failure detection module. When the dynamic power failure detection module determines that the external power supply has failed, the vehicle fault prediction and health management system continues to execute the read and write operations that the file system is currently processing, and does not create new read and write tasks. During the discharge of the supercapacitor, the discharge current and voltage of the supercapacitor are sampled synchronously by a high-precision ADC. The total charge released to the load during the discharge of the supercapacitor is calculated by integrating the current with the discharge time. At the same time, the actual capacity of the supercapacitor is calculated by measuring the voltage difference of the supercapacitor. The capacity parameters are stored in the non-volatile memory of the vehicle fault prediction and health management system. The file system protection system based on the time delay power-off circuit further comprises a capacitor charging control module, which is used for controlling the charging termination voltage U of the super capacitor during charging MAX .

2. The time-out de-energized circuit based file system protection system of claim 1, wherein, The charge termination voltage U MAX Calculated by the following relationship: Wherein the capacitance of the capacitor is C, the capacitance C is obtained by measurement, the charging termination voltage of the capacitor is U MAX , the discharge termination voltage is U MIN , U MIN is determined by the minimum supply voltage of the device, and W is the energy required during file system protection obtained by testing.

3. The time-out de-energized circuit based file system protection system of claim 2, wherein, When U MAX is less than or equal to U MIN , the super capacitor is maintained.

4. The time-out de-energized circuit based file system protection system of claim 1, wherein, The capacitor charging control module includes a DC / DC controller U5 with CI / CV function, which is fed by an external DC power supply of 12V to 24V. It is used to control the charging of the supercapacitor. When the supercapacitor charging has not reached the limit, it is in constant current control mode. Charging stops after the set voltage is reached.

5. The time-out de-energized circuit based file system protection system of claim 4, wherein, The capacitor charging control module also includes: The first operational amplifier U55A takes the DAC output signal from the microcontroller as input and connects its output to the voltage feedback pin of the DC / DC controller U5 via a voltage divider resistor R485. The microcontroller adjusts the output voltage of the DAC to dynamically adjust the output voltage of the DC / DC controller U5, thereby adjusting the charging termination voltage of the supercapacitor. The voltage of the supercapacitor is divided by the second resistor R487 and the third resistor R488 and then buffered by the second operational amplifier U57A before being connected to the second channel of the microcontroller's ADC. The capacitor voltage is obtained through AD conversion. The precision instrument amplifier U56 takes the voltage across the sampling resistor R421 of the supercapacitor discharge circuit as its input signal. The amplifier gain is set by the fourth resistor R486, and after being amplified to a certain ratio, it is connected to the first channel of the microcontroller's ADC. The circuit current value is obtained through AD conversion. The microcontroller's ADC is set to synchronous sampling mode to ensure that voltage and current are sampled synchronously.

6. The time-out de-energized circuit based file system protection system of claim 5, wherein, The relationship between the output voltage of DC / DC controller U5 and the DAC voltage is as follows: wherein V DAC is an output voltage of pin No. 4 of the first operational amplifier U55A, V FB is a feedback reference voltage of the DC / DC controller U5, V OUT is a set output voltage of the DC / DC controller U5, R 485 is a resistance value of the resistor R485, R 422 is a resistance value of the resistor R422, R 423 is a resistance value of the resistor R423.

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