A standby control method for backup power supply based on feedback difference

Abstract

The present application relates to power supply redundancy control technical field, specifically, the present application relates to a kind of standby power standby control method based on feedback difference, the present application is by collecting the feedback of main road and backup road and shared output sampling voltage, according to amplitude difference, difference of change rate and response difference generates main backup feedback difference data, combined with cumulative timing and dynamic threshold generation energy detection instruction, through main road reduces the first test energy unit, backup road injects equivalent second test energy unit Symmetrical detection, obtain double-source energy response data, calculate voltage energy response coefficient and current energy response coefficient, according to this distinguish main road energy side fault and load side fault, calculate main road residual magnetic energy parameter when main road fault, establish backup road preset magnetic energy parameter in isolation state, determine takeover phase based on two-way magnetic energy matching, complete load smooth transfer by voltage loop and current distribution loop double-loop superposition control, improve fault positioning accuracy.

Description

Technical Field

[0001] This invention relates to the field of power redundancy control technology, and more specifically, to a backup power standby control method based on feedback differences. Background Technology

[0002] Existing backup power systems typically determine whether the main circuit is abnormal by detecting the main circuit output voltage, main circuit feedback signal, or main circuit PWM duty cycle. When undervoltage, overcurrent, or feedback deviation is detected, the backup circuit is activated to maintain continuous power supply to the load. To reduce the power consumption generated by the long-term operation of the backup circuit, some systems will keep the backup circuit in a closed or intermittent standby state and restore the PWM control of the backup circuit after the main circuit fails. However, in actual power supply, the decrease in the main circuit power supply capacity and the load-side short circuit, insulation breakdown, or abnormal current path may exhibit similar electrical characteristics, such as a decrease in common output voltage, an increase in load current, and an increase in the main circuit PWM duty cycle. Existing systems usually cannot accurately determine whether the fault is on the main circuit power supply side or the load side based on the above signals. If the load-side fault is mistakenly identified as a main circuit fault and the backup circuit is directly activated, the backup circuit will continue to supply energy to the fault location, which may cause an increase in abnormal current, line heating, or an expansion of the fault range. If the judgment time is extended to reduce the risk of misconnection, it may cause power interruption when the main circuit actually fails. Furthermore, after a power supply failure is confirmed in the main circuit, a certain amount of residual current and magnetic energy are usually still retained in the main circuit output inductor. The backup circuit, which is in standby mode, needs to rebuild the inductor current. Existing backup takeover methods mostly use direct start or fixed soft start control, which do not fully consider the relationship between the decay process of the main circuit residual current and the establishment process of the backup circuit output current. When the backup circuit output current is established too quickly, it may be superimposed with the main circuit residual current, causing overshoot of the shared output voltage or circulating current in the main and backup branches. When the backup circuit output current is established too slowly, the output voltage may drop during the period when the main circuit residual current has decayed but the backup circuit current has not yet formed. Therefore, existing technologies still need to address how to accurately distinguish between main power supply side faults and load side faults based on the feedback difference between the main and backup power supply sides, and how to coordinate the residual magnetic energy of the main power supply side and the preset magnetic energy of the backup power supply side after confirming the main power supply side fault, so that the backup power supply side can complete a smooth and continuous power supply takeover while avoiding the continued injection of energy into the load side fault. In order to solve this technical problem, we provide a backup power supply standby control method based on feedback difference. Summary of the Invention

[0003] The purpose of this invention is to provide a backup power standby control method based on feedback difference to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, one objective of this invention is to provide a backup power supply standby control method based on feedback differences, comprising the following steps: S1. Collect the main feedback quantity, backup feedback quantity, common output sampling voltage, main PWM duty cycle status and load change data. Generate main and backup feedback difference data based on the amplitude difference, rate of change difference and response difference relative to the common output sampling voltage between the main and backup feedback quantities and the backup feedback quantity. Generate energy detection command when the main and backup feedback difference data meet the preset abnormal conditions. S2. According to the energy detection command, maintain the backup circuit in an unsteady state and control the main circuit to reduce the first test energy unit during the first detection period, and the backup circuit to inject the second test energy unit during the second detection period. The absolute values ​​of the first test energy unit and the second test energy unit are equal. Obtain the common output sampling voltage change, load current increment, main circuit feedback recovery trajectory and backup circuit feedback response trajectory in the two periods respectively to form dual-source energy response data. S3. Based on the dual-source energy response data, determine the energy response relationship between the recovery amount of the common output sampling voltage and the increment of the load current corresponding to the second test energy unit. When the second test energy unit restores the common output sampling voltage and the increment of the load current is within the normal response range, generate the main power supply side fault result. When it fails to restore the common output sampling voltage and the increment of the load current exceeds the normal response range, generate the load side fault result and limit the energy injected into the backup line. S4. Based on the fault results of the main power supply side, according to the duty state of multiple PWM cycles before and after the first detection period of the main road, the main road feedback recovery trajectory and the change of the common output sampling voltage, determine the direction of the residual current of the main output inductor, the residual current decay trajectory and the time of residual magnetic energy release, generate the main road residual magnetic energy parameters, and control the backup PWM chip to exit intermittent standby, establish a preset current in the internal freewheeling circuit of the backup road and the common output terminal under controlled isolation, and generate the backup road preset magnetic energy parameters. S5. Determine the control phase of the backup circuit connected to the common output terminal based on the residual magnetic energy parameters of the main circuit and the preset magnetic energy parameters of the backup circuit. Control the backup circuit to release the preset magnetic energy in the control phase so that the attenuation of the residual current of the main circuit matches the increase of the output current of the backup circuit. Continuously adjust the PWM duty cycle of the backup circuit based on the common output sampling voltage and the main / backup feedback difference data until the load power supply is transferred from the main circuit to the backup circuit.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention generates primary and backup feedback difference data by using the main feedback quantity, backup feedback quantity, common output sampling voltage, main PWM duty cycle state and load change data, and forms dual-source energy response data by reducing test energy in the main path and injecting test energy in the backup path. It can distinguish between main power supply side faults and load side faults from the perspective of actual energy response, and reduce misjudgments caused by relying solely on undervoltage or overcurrent signals. When the fault is determined to be on the load side, the present invention limits the energy injected by the backup circuit to the common output terminal, and avoids the backup circuit from continuing to increase the fault energy when the load is short-circuited, the insulation is broken or an abnormal current path exists, thereby reducing the risk of abnormal current expansion, device overheating and fault propagation. When the fault is determined to be located on the main power supply side, this method determines the direction of the residual current, the residual current decay trajectory, and the time of residual magnetic energy release of the main output inductor based on the main PWM duty cycle, the main feedback recovery trajectory, and the change of the common output sampling voltage. This improves the observability of the main power supply process and provides an accurate basis for determining the backup power supply phase. When the backup circuit and the common output terminal are kept in controlled isolation, the present invention establishes a preset current in the internal freewheeling loop of the backup circuit in advance, so that the backup circuit has the corresponding magnetic energy and current state before it is formally connected to the common output terminal, thereby reducing the current establishment delay caused by the zero current state start-up of the backup circuit. This invention determines the takeover phase based on the residual magnetic energy parameters of the main circuit and the preset magnetic energy parameters of the backup circuit, so that the attenuation of the residual current of the main circuit matches the increase of the output current of the backup circuit. This can reduce the output voltage drop, voltage overshoot and branch circuit circulating current during the main-to-backup switching process, and improve the stability, timeliness and continuous power supply reliability of the backup takeover. Attached Figure Description

[0006] Figure 1 This is a flowchart illustrating the overall workflow of the present invention. Detailed Implementation

[0007] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0008] Please see Figure 1 As shown, one of the objectives of this embodiment is to provide a backup power supply standby control method based on feedback differences, including the following steps: S1. Collect the main feedback quantity, backup feedback quantity, common output sampling voltage, main PWM duty cycle status and load change data. Generate main and backup feedback difference data based on the amplitude difference, rate of change difference and response difference relative to the common output sampling voltage between the main and backup feedback quantities and the backup feedback quantity. Generate energy detection command when the main and backup feedback difference data meet the preset abnormal conditions. S2. According to the energy detection command, maintain the backup circuit in an unsteady state and control the main circuit to reduce the first test energy unit during the first detection period, and the backup circuit to inject the second test energy unit during the second detection period. The absolute values ​​of the first test energy unit and the second test energy unit are equal. Obtain the common output sampling voltage change, load current increment, main circuit feedback recovery trajectory and backup circuit feedback response trajectory in the two periods respectively to form dual-source energy response data. S3. Based on the dual-source energy response data, determine the energy response relationship between the recovery amount of the common output sampling voltage and the increment of the load current corresponding to the second test energy unit. When the second test energy unit restores the common output sampling voltage and the increment of the load current is within the normal response range, generate the main power supply side fault result. When it fails to restore the common output sampling voltage and the increment of the load current exceeds the normal response range, generate the load side fault result and limit the energy injected into the backup line. S4. Based on the fault results of the main power supply side, according to the duty state of multiple PWM cycles before and after the first detection period of the main road, the main road feedback recovery trajectory and the change of the common output sampling voltage, determine the direction of the residual current of the main output inductor, the residual current decay trajectory and the time of residual magnetic energy release, generate the main road residual magnetic energy parameters, and control the backup PWM chip to exit intermittent standby, establish a preset current in the internal freewheeling circuit of the backup road and the common output terminal under controlled isolation, and generate the backup road preset magnetic energy parameters. S5. Determine the control phase of the backup circuit connected to the common output terminal based on the residual magnetic energy parameters of the main circuit and the preset magnetic energy parameters of the backup circuit. Control the backup circuit to release the preset magnetic energy in the control phase so that the attenuation of the residual current of the main circuit matches the increase of the output current of the backup circuit. Continuously adjust the PWM duty cycle of the backup circuit based on the common output sampling voltage and the main / backup feedback difference data until the load power supply is transferred from the main circuit to the backup circuit.

[0009] The generation process of primary and backup feedback difference data characterizes the deviation of the two feedback signals from multiple dimensions, avoiding false triggering of detection commands due to misjudgment from a single dimension, and improving the accuracy of anomaly identification. In each sampling period, the instantaneous values ​​of the primary and backup feedback quantities are simultaneously acquired. The primary feedback quantity represents the voltage signal obtained by converting the primary output current through a sampling resistor, with the dimension in volts. The backup feedback quantity represents the voltage signal obtained by converting the backup output current through a sampling resistor, also with the dimension in volts. Both feedback signals use the same type of sampling resistor and the same gain signal conditioning circuit to ensure consistent dimensions and sensitivity. The amplitude difference between the primary and backup feedback quantities at the same sampling moment is calculated, and its absolute value is taken to obtain the amplitude difference quantity. The formula for calculating the amplitude difference quantity is as follows: in Represents the current sampling period number. Representing the The instantaneous value of the main path feedback collected in each sampling period Representing the The instantaneous value of the backup path feedback collected in each sampling period. Representing the The amplitude difference per sampling period is measured in volts. For example, when the instantaneous value of the main feedback is 2.5 volts and the instantaneous value of the backup feedback is 2.3 volts, the corresponding amplitude difference is 0.2 volts. The amplitude difference directly reflects the static deviation of the two feedback signals at the same moment. When output drift occurs in either the main or backup path, the amplitude difference will immediately increase. The amplitude difference is used in the amplitude threshold comparison stage in subsequent abnormal condition judgment.

[0010] After calculating the amplitude difference, the calculation of the rate of change difference begins. Within a preset sliding time window, the unit-time rate of change of the main path feedback and the backup path feedback is calculated respectively. The sliding time window includes continuous... Each sampling period, The value of N is adaptively adjusted according to the load change rate. When the load change rate increases, N decreases to improve response speed; when the load change rate decreases, N increases to suppress noise interference. The window length can be adjusted from 5 to 20 sampling periods. The formula for calculating the unit time change rate of the main path feedback is as follows: in This represents the sampling period, measured in seconds. Representing the The rate of change of the main feedback quantity per unit time, calculated from each sampling period, is expressed in volts per second.

[0011] The rate of change of the backup path feedback quantity per unit time is calculated using the same formula and denoted as . The difference in rate of change is obtained by calculating the absolute value of the difference between the rate of change per unit time of the main path feedback quantity and the rate of change per unit time of the backup path feedback quantity. The formula for calculating the rate of change difference is as follows: Representing the The difference in the rate of change per sampling period, measured in volts per second. For example, when the sliding window contains 10 sampling periods, with each sampling period being 10 microseconds, and the main feedback quantity changes by 0.5 volts within the window while the backup feedback quantity changes by 0.3 volts within the window, the rate of change per unit time for the main path is approximately 5555.6 volts per second, and the rate of change per unit time for the backup path is approximately 3333.3 volts per second. The corresponding difference in the rate of change is approximately 2222.3 volts per second.

[0012] The rate of change difference reflects the difference in the dynamic change speed of the two feedback signals. When a power supply experiences a response hysteresis or a change in loop gain, the rate of change difference will appear abnormal before the amplitude difference. The rate of change difference is used to capture the dynamic characteristics of the initial stage of the fault in advance, providing a basis for judgment of the rate of change dimension for subsequent abnormal conditions.

[0013] After completing the calculation of the rate of change difference, the response difference calculation stage begins. The moment when the common output sampling voltage undergoes a step change is collected as a reference moment. The common output sampling voltage represents the voltage sampling value at the load input terminal, with the dimension in volts. A step change refers to a voltage jump in which the voltage change exceeds a preset step threshold within a single sampling period. The jump direction includes both rising and falling steps.

[0014] Calculate the response delay and steady-state response amplitude deviation of the main feedback quantity relative to the reference time. The response delay is the time difference between the reference time and the moment when the main feedback quantity begins to change accordingly, measured in seconds. The steady-state response amplitude deviation is the deviation between the change in the main feedback quantity when it reaches a stable value after the step change and the theoretical value calculated proportionally from the step value of the shared output sampling voltage, measured in volts. The main response delay is denoted as... The amplitude deviation of the steady-state response of the main road is denoted as .

[0015] The backup path feedback quantity was calculated using the same method to obtain the backup path response delay. And the steady-state response amplitude deviation of the backup path The absolute value of the difference between the main path response delay and the backup path response delay, and the absolute value of the difference between the main path steady-state response amplitude deviation and the backup path steady-state response amplitude deviation, are combined to form the response difference quantity. The response difference quantity comprises two components: a delay difference component and an amplitude deviation difference component. The formula for calculating the delay difference component is as follows: The component representing the time delay difference, with the dimension in seconds, is calculated using the following formula: The amplitude deviation component represents the difference in magnitude, measured in volts. For example, when the main response delay is 50 microseconds, the backup response delay is 80 microseconds, the steady-state response amplitude deviation of the main path is 0.02 volts, and the steady-state response amplitude deviation of the backup path is 0.05 volts, the corresponding delay difference component is 30 microseconds, and the amplitude deviation difference component is 0.03 volts. The response difference reflects the difference in the ability of the two feedback channels to follow the same output disturbance. When the bandwidth of a certain feedback loop changes or a phase shift occurs in the sampling path, the response difference will be abnormal. The response difference is used to distinguish the difference caused by changes in the characteristics of the feedback channel itself and normal load fluctuations. To further improve the discriminative power of the difference assessment, the amplitude difference, the rate of change difference, and the response difference are weighted and fused to obtain a comprehensive difference assessment value. The weighted fusion formula is as follows: in This represents the rated reference voltage for feedback, in volts. This represents the nominal response delay reference value, measured in seconds. These represent the magnitude weight, rate of change weight, and response weight, respectively. The sum of these three weights equals 1, and their values ​​are set according to the system's sensitivity to anomalies in different dimensions. Representing the The comprehensive difference assessment value for each sampling period is a dimensionless value.

[0016] Before weighted fusion, each component is normalized to eliminate weight imbalances caused by differences in dimensions, ensuring that the differences among the three dimensions participate in the evaluation on the same scale. For example, when... The value is 2.5 volts. The value is 50 microseconds. Take 0.4, Take 0.3, When the amplitude difference is 0.3, the rate of change difference is 2222.3 volts per second, the sampling period is 10 microseconds, the time delay difference component is 30 microseconds, and the amplitude deviation difference component is 0.03 volts, the comprehensive difference assessment value is approximately 0.4×0.08+0.3×0.00889+0.3×(0.6+0.012), and the calculated result is approximately 0.219. The comprehensive difference assessment value is used for the comprehensive judgment of subsequent preset abnormal conditions. Combined with the independent thresholds of each component difference, multi-level anomaly identification is achieved. The amplitude difference, rate of change difference, response difference, and comprehensive difference assessment value are combined to form the primary and backup feedback difference data. The primary and backup feedback difference data are updated in real time with each sampling period and are used for subsequent abnormal condition judgment and feedback adjustment in the energy detection stage. The multi-dimensional difference data can cover three types of abnormal scenarios: static deviation, dynamic change, and loop characteristics, reducing the probability of missed detection.

[0017] The generation process of energy detection commands adopts a mechanism of multi-threshold hierarchical judgment combined with duration verification, which can filter out sampling noise and false triggers caused by load transient fluctuations, ensuring that the detection action is initiated only when an actual anomaly occurs. The amplitude difference threshold, rate of change difference threshold, and response difference threshold are preset. The amplitude difference threshold represents the minimum amplitude difference required to trigger an anomaly judgment, with the unit being volts. The rate of change difference threshold represents the minimum rate of change difference required to trigger an anomaly judgment, with the unit being volts per second. The response difference threshold includes two sub-items: the delay difference threshold and the amplitude deviation difference threshold. The delay difference threshold has the unit being seconds, and the amplitude deviation difference threshold has the unit being volts.

[0018] To accommodate normal fluctuations under different load conditions, all three thresholds are dynamically adjusted. The threshold reference values ​​are corrected based on the ratio of the current load current to the rated current. The dynamic adjustment formula is as follows: in This represents the threshold of amplitude difference under the current operating conditions. Represents the threshold value for amplitude difference. This represents the ratio of the current load current to the rated load current, and its value ranges from 0 to 1. The load correction factor represents the amplitude threshold. This represents the threshold of the rate of change difference under the current operating conditions. Represents the threshold value for the difference in rate of change. The load correction factor represents the threshold of the rate of change. This represents the threshold value for time delay difference under the current operating conditions. This represents the baseline value for the latency difference threshold. The load correction factor represents the latency threshold. This represents the threshold value for amplitude deviation under the current operating conditions. This represents the threshold benchmark value for amplitude deviation difference. The load correction coefficient represents the amplitude deviation threshold.

[0019] All four correction coefficients are positive, with higher thresholds corresponding to larger loads. This adapts to the increased normal fluctuation amplitude under heavy loads. The dynamic threshold avoids missed detections due to excessively high thresholds under light loads and false detections due to excessively low thresholds under heavy loads, improving the adaptability of anomaly detection under different operating conditions. After the threshold calculation is completed, a comparison phase is initiated. The amplitude difference in the primary and backup feedback difference data is compared with the amplitude difference threshold, the rate of change difference is compared with the rate of change threshold, the delay difference component in the response difference is compared with the delay difference threshold, and the amplitude deviation difference component in the response difference is compared with the amplitude deviation difference threshold. The comparison results are divided into four triggering conditions: the first condition is that the amplitude difference exceeds the amplitude difference threshold, the second condition is that the rate of change difference exceeds the rate of change threshold, the third condition is that the delay difference component exceeds the delay difference threshold, and the fourth condition is that the amplitude deviation difference component exceeds the amplitude deviation difference threshold.

[0020] When any of the following conditions are met, the corresponding sub-item's abnormal timing is initiated. Abnormal timing uses a cumulative timing method: when the difference exceeds a threshold in each sampling period, the timing increments by one sampling period. When the difference falls back below the threshold, the timing neither decreases nor resets to zero, but remains at its current value until the difference exceeds the threshold again, at which point it continues to increment. The formula for calculating the cumulative abnormal timing duration is as follows: in Representing the The cumulative anomaly timing duration at the end of each sampling period. This represents the sampling period, measured in seconds.

[0021] Cumulative timing allows for brief dips during abnormal processes, preventing the timing from being reset when noise at a single sampling point falls below the threshold, thus adapting to the fluctuating characteristics during fault development.

[0022] For example, if the preset duration of an anomaly is 1 millisecond and the sampling period is 10 microseconds, it requires 100 anomaly sampling points to trigger. If a fallback occurs every 10 sampling points during the anomaly process, the continuous timing method requires 110 sampling periods to complete, while the cumulative timing method only requires 100 sampling periods to complete, thus realizing the timing statistics of intermittent anomalies.

[0023] In addition to the OR logic triggering of the sub-item thresholds, a comprehensive difference assessment threshold is also set as a second judgment condition. The comprehensive difference assessment value in the primary and backup feedback difference data is compared with the comprehensive difference threshold. When the comprehensive difference assessment value exceeds the comprehensive difference threshold, the comprehensive anomaly timer is also started. The comprehensive anomaly timer adopts the same cumulative calculation method as the sub-item anomaly timer.

[0024] When the cumulative duration of either the sub-item anomaly timing or the overall anomaly timing reaches the preset anomaly duration, the final verification stage begins.

[0025] The final verification process checks the overall trend of the corresponding difference quantity within the duration of the anomaly, calculates the ratio of the average value of the corresponding difference quantity within the anomaly period to the threshold, and generates an energy detection command directly when the ratio is greater than 1.2. When the ratio is between 1 and 1.2, it further checks the trend of the difference quantity. When the difference quantity shows a continuous upward trend, an energy detection command is generated. When the difference quantity shows a downward trend, no energy detection command is generated and the corresponding anomaly timer is reset to zero.

[0026] The generated energy detection command carries a trigger source identifier, which records the difference type of the trigger anomaly judgment. This identifier is used to select the corresponding data parsing focus in the subsequent detection process. After the energy detection command is generated, it is sent to the main road control unit and the backup road control unit to start the dual-source energy detection process. The fault location is further located by actively injecting test energy.

[0027] The dual-source energy detection process adopts a symmetrical execution method of main path reduction and backup path increment. It can distinguish whether the fault occurs on the power supply side or the load side by the different effects of the two energy changes on the output voltage and load current, and provide a quantitative basis for subsequent fault location.

[0028] Before the detection begins, the backup PWM chip maintains an intermittent standby state. The intermittent standby state refers to a low-power operating mode in which the internal clock and reference source of the PWM chip remain active, and the power transistor drive output is in the off state. The internal freewheeling circuit of the backup circuit remains conducting. The internal freewheeling circuit refers to the closed circuit composed of the output inductor and freewheeling diode of the backup circuit. The current in the circuit can maintain flow without being connected to the common output terminal. The isolation switch between the output side of the backup circuit and the common output terminal remains open, so that the backup circuit does not continuously output energy to the common output terminal, and only maintains the minimum operating state of the internal circuit of the backup circuit. The minimum operating state includes two parts: the power supply of the PWM chip and the power supply of the internal reference voltage circuit, ensuring that it can enter the working state within microseconds after receiving the wake-up signal.

[0029] Upon receiving the energy detection command, the first step is to calculate the value of the first test energy unit. The first test energy unit refers to the total output energy that the main circuit needs to reduce during the first detection period, measured in joules. The first test energy unit is adaptively calculated based on the current output voltage and output capacitor value to ensure that the voltage drop caused by the detection is within a preset measurable range and does not affect the normal operation of the load. The formula for calculating the first test energy unit is as follows: in Represents the first unit of energy tested. This represents the total output capacitance value shared by the output terminals, measured in farads. This represents the current shared output sampling voltage value, in volts. This represents the preset target voltage drop amplitude, measured in volts.

[0030] For example, when the output capacitance is 1000 microfarads, the output voltage is 12 volts, and the target voltage drop is 0.1 volts, the first test energy unit is 1000e-6 farads multiplied by 12 volts multiplied by 0.1 volts, resulting in 0.0012 joules. After obtaining the first test energy unit, the required reduction in the main PWM duty cycle is calculated. Based on the relationship between the output inductor current and the duty cycle in the buck topology, the relationship between the reduction in output energy per cycle and the reduction in duty cycle is as follows: in This represents the reduction in the duty cycle of the main road, and is a dimensionless value. This represents the number of PWM cycles contained in the first detection period. This represents the PWM switching cycle, measured in seconds. This represents the main input voltage, measured in volts. This represents the current load current, measured in amperes.

[0031] The duty cycle reduction action is executed synchronously at the start edge of the PWM cycle at the beginning of the first detection period, ensuring that energy changes are calculated from the start of a complete cycle and avoiding energy calculation errors caused by non-integer cycles.

[0032] The first detection period covers at least three complete PWM cycles. The actual number of cycles is adjusted based on the test energy and load current to ensure that the voltage drop process is completed and stabilizes within the first detection period. The second detection period begins immediately after the first detection period ends, with no interval between the two periods, ensuring continuous measurability of the output voltage change. Before entering the second detection period, the value of the second test energy unit is confirmed. The absolute value of the energy in the second test energy unit is equal to that in the first test energy unit. , Representing the second unit of energy measured in joules, it is a controlled path between the internal freewheeling circuit of the closed backup circuit and the common output terminal. The controlled path refers to a power path composed of MOSFETs that can be controlled to switch on and off. The on-resistance is in the milliohm range, and the switching action can be completed within a single PWM cycle, allowing the energy stored in the inductor inside the backup circuit to be released to the common output terminal.

[0033] The energy injection process employs a time-controlled method, controlling the total injected energy by calculating the duration of the backup circuit inductor current released to the output. The relationship between injected energy and conduction time is as follows: in This represents the duration of controlled pathway conduction, measured in seconds. This represents the preset current value of the internal inductor of the backup circuit, in amperes. The forward voltage drop of the freewheeling diode is represented by volts. After energy injection is completed, the controlled path is immediately disconnected, and the energy transmission from the backup path to the common output terminal is stopped. The duration of the second detection period is equal to that of the first detection period to ensure that the two energy input times are symmetrical, which facilitates subsequent data comparison and analysis. For example, when the first detection period contains 5 PWM cycles and the switching cycle is 20 microseconds, the first detection duration is 100 microseconds, and the second detection duration is also set to 100 microseconds. During the entire dual-source energy detection process, the common output sampling voltage, load current, main path feedback quantity, and backup path feedback quantity are continuously collected to form dual-source energy response data for subsequent fault location judgment. Symmetrical energy injection can eliminate the judgment deviation caused by the difference in time dimension and improve the accuracy of fault location.

[0034] The dual-source energy response data formation process employs synchronous sampling combined with filtering, enabling complete recording of the dynamic changes in voltage and current during both detection periods. This provides comprehensive data support for subsequent fault location and judgment. During the first detection period, instantaneous values ​​of the shared output sampling voltage, load current, and main feedback quantity are continuously acquired at a preset sampling frequency. The sampling frequency is set to an integer multiple of the PWM switching frequency, and the sampling time is aligned with the midpoint of the PWM switching cycle to avoid noise spikes during power transistor switching, thus improving the signal-to-noise ratio of the sampled data. The sampled data then enters a first-order moving average filtering stage, with the filtering formula as follows: in Representing the The filtered values ​​from each sampling point have the same dimensions as the original sampling values. Representing the The values ​​of each original sampling point. The value represents the sliding window length. Filtering suppresses the impact of switching ripple and high-frequency noise on subsequent calculations while preserving the overall trend of the signal. Using the common output sampling voltage at the start of the first detection period as the reference value, which is the average of the three sampling points before the start of the first detection period, further reducing the random error of the reference value, the difference between the filtered value of the common output sampling voltage at the end of the first detection period and the reference value is calculated to obtain the voltage change in the first period. The formula for calculating the voltage change in the first period is: in This represents the voltage change during the first time period, measured in volts. The shared output sampling voltage filter value represents the end time of the first detection period. The reference voltage value represents the starting time of the first detection period.

[0035] For example, when the initial reference voltage is 12.0 volts and the final voltage is 11.9 volts, the voltage change in the first period is -0.1 volts. The negative sign indicates a voltage drop. The increment of the load current in the first period is calculated by subtracting the maximum load current value from the initial load current value. This is done by iterating through all filtered load current sampling points within the first period, comparing them to obtain the maximum value, and then subtracting the initial load current value. The formula for calculating the increment of the load current in the first period is as follows: in This represents the increase in load current during the first time period, measured in amperes. This represents the maximum value of the load current sampling points during the first detection period. This represents the load current value at the start of the first detection period.

[0036] The main path feedback recovery trajectory is formed by arranging all filtered sampling points of the main path feedback during the first detection period in chronological order. The main path feedback recovery trajectory is time series data. Each data point contains a timestamp and the corresponding feedback value. The timestamp is normalized with the start time of the first detection period as zero point to facilitate time alignment and comparison with other trajectories in the future.

[0037] After completing the data acquisition and processing for the first detection period, the data acquisition phase for the second detection period begins. During the second detection period, the instantaneous values ​​of the shared output sampling voltage, load current, and backup circuit feedback are continuously acquired at the same sampling frequency. The sampling frequency and filtering parameters are kept completely consistent with those of the first detection period to ensure that the data accuracy and response characteristics of the two periods are consistent and to eliminate system errors caused by differences in sampling parameters.

[0038] Using the common output sampling voltage at the start of the second detection period as the reference value, and taking the average of the filtered values ​​of the three sampling points before the start of the second detection period as the reference value, the voltage change in the second period is calculated by subtracting the filtered value of the common output sampling voltage at the end of the second detection period from the reference value. The formula for calculating the voltage change in the second period is as follows: in This represents the voltage change during the second time period, measured in volts. The shared output sampling voltage filter value represents the end time of the second detection period. This represents the reference voltage value at the start of the second detection period. The difference between the maximum load current during the second detection period and the load current at the start is used to calculate the load current increment for the second period. The calculation method is exactly the same as for the load current increment in the first period. The formula for calculating the load current increment in the second period is: in This represents the increase in load current during the second time period, measured in amperes. This represents the maximum value of the load current sampling points during the second detection period. This represents the load current value at the start of the second detection period.

[0039] The sampling points of all backup path feedback quantities filtered during the second detection period are arranged in chronological order to form the backup path feedback response trajectory. The backup path feedback response trajectory also uses a normalized timestamp, with the zero point of the time being the start time of the second detection period.

[0040] In addition to the original trajectory data, feature points were extracted from the two feedback trajectories. Four feature parameters were extracted: rising edge slope, falling edge slope, peak position, and steady-state value. These feature parameters are used for rapid comparison during subsequent fault location, reducing the amount of data calculated point by point.

[0041] The voltage change in the first time period, the load current increment in the first time period, the main feedback recovery trajectory, the voltage change in the second time period, the load current increment in the second time period, and the backup feedback response trajectory are combined to form the dual-source energy response data. The dual-source energy response data also includes trajectory characteristic parameters of the two time periods as auxiliary data.

[0042] After the dual-source energy response data is generated, it is sent to the fault location and judgment stage to calculate the energy response relationship and distinguish the fault type. The unified format of the response data can ensure the consistency of the subsequent judgment logic and improve the reliability of the fault location results.

[0043] The calculation process of energy response relationship is used to quantify the response amplitude of output voltage and load current under the action of unit test energy, and to provide a quantitative judgment benchmark for distinguishing between main circuit faults and load faults.

[0044] First, the voltage change in the first time period and the voltage change in the second time period are extracted from the dual-source energy response data. The voltage change in the first time period represents the total change in the shared output sampling voltage after the main circuit reduces the first test energy unit, and the dimension is volts. The voltage change in the second time period represents the total change in the shared output sampling voltage after the backup circuit injects the second test energy unit, and the dimension is volts.

[0045] The absolute value of the voltage change in the first time period is used as the voltage sag reference value. This reference value represents the output voltage sag caused by the main circuit reduction, providing a reference zero point for subsequent recovery calculations. To eliminate the influence of switching ripple on the calculation results, a ripple correction is applied to the voltage sag reference value. The correction method is to subtract half the peak-to-peak value of the voltage ripple during the first detection period from the reference value. The correction formula is as follows: in This represents the corrected voltage drop reference value, in volts. This represents the voltage change during the first time period. The voltage ripple peak-to-peak value during the first detection period is represented by volts. The voltage change during the second period is added to the voltage drop reference value to obtain the common output sampling voltage recovery value. This common output sampling voltage recovery value represents the recovery magnitude of the output voltage relative to the lowest point of the voltage drop after energy injection from the backup circuit. The calculation formula is as follows: This represents the recovery amount of the shared output sampling voltage, measured in volts. For example, when the voltage change in the first time period is -0.1 volts, the peak-to-peak voltage ripple in the first time period is 0.01 volts, the corrected voltage drop reference value is approximately 0.095 volts, and the voltage change in the second time period is 0.08 volts, the recovery amount of the shared output sampling voltage is approximately 0.175 volts.

[0046] The recovery amount of the shared output sampling voltage directly reflects the effect of the energy injected by the backup circuit on the output voltage. When the recovery amount is close to the voltage drop reference value, it indicates that the energy is mainly used to supplement the output capacitor voltage. When the recovery amount is much less than the voltage drop reference value, it indicates that the energy is consumed by the load side.

[0047] After calculating the voltage recovery, the load current increment for the second time period is extracted from the dual-source energy response data. This increment represents the maximum increase in load current during the backup circuit energy injection process, measured in amperes. The load current increment reflects the current response amplitude on the load side after the test energy injection. Next, the voltage energy response coefficient is calculated. This coefficient represents the output voltage recovery amplitude corresponding to a unit energy injection. A backup circuit efficiency correction coefficient is introduced during the calculation to compensate for energy losses caused by the controlled circuit's on-resistance and the freewheeling diode's voltage drop. The formula for calculating the voltage energy response coefficient is as follows: in This represents the voltage energy response coefficient, with dimensions in volts per joule. This represents the energy value of the second test energy unit, with the dimension of joules. The efficiency correction coefficient for the backup energy injection path ranges from 0 to 1. For example, when the voltage recovery is 0.175 volts, the second test energy unit is 0.0012 joules, and the path efficiency is 0.95, the voltage energy response coefficient is approximately 153.5 volts per joule. This voltage energy response coefficient is used to compare with a preset voltage response threshold to determine if the voltage recovery level matches the characteristics of a main circuit fault. Subsequently, the current energy response coefficient is calculated. The current energy response coefficient represents the increment of the load current corresponding to a unit energy injection, and the calculation formula is as follows: in The current energy response coefficient is expressed in amperes per joule. This represents the load current increment in the second time period. For example, when the load current increment is 0.5 amperes, the second test energy unit is 0.0012 joules, and the path efficiency is 0.95, the current energy response coefficient is approximately 438.6 amperes per joule. The current energy response coefficient is used to compare with the preset current response threshold to determine whether the current increment is within the normal response range. To ensure the validity of the response coefficient, a response linearity check is performed after the calculation is completed. The recovery amount of the common output sampling voltage is compared with the upper limit of the preset linear range. When the recovery amount is less than the upper limit of the linear range, the response is determined to be in the linear region, and the response coefficient can be directly used for subsequent judgment. When the recovery amount is greater than or equal to the upper limit of the linear range, the response is determined to have entered the saturation region, and a saturation mark is added to the energy response relationship to prompt the subsequent judgment logic to apply additional margin.

[0048] The energy response relationship corresponding to the second test energy unit is composed of the shared output sampling voltage recovery, load current increment, voltage energy response coefficient, current energy response coefficient, and saturation mark. The energy response relationship is used as input data for the fault location link to distinguish between main power supply side faults and load side faults. The quantified response coefficient can provide a unified scale for threshold judgment and avoid the problem of threshold adaptation difficulties under different operating conditions.

[0049] The fault location and identification process adopts a dual-dimensional joint judgment method of voltage recovery and current increment, which can distinguish between power supply side abnormalities and load side abnormalities, avoid fault location deviations caused by single-dimensional judgment, and provide a basis for different handling strategies for different fault types.

[0050] A voltage recovery threshold and a normal load current response range are preset. The voltage recovery threshold represents the minimum recovery amount required to determine effective voltage recovery, with the dimension being volts. The normal load current response range includes two boundaries: an upper limit and a lower limit for current increment, both with the dimension being amperes. The normal response range corresponds to the current increment range caused by energy injection under normal load fluctuations. Both thresholds are adaptively adjusted based on the current load current. The adjustment formula for the voltage recovery threshold is as follows: in This represents the voltage recovery threshold under the current operating conditions. This represents the voltage recovery threshold reference value. Represents the current load factor. The load correction factor represents the voltage threshold, and the formula for adjusting the upper limit of the normal response range of the load current is as follows: in This represents the upper limit of the current increment under the current operating conditions. This represents the upper limit reference value for current increment. The load correction factor represents the current threshold. The lower limit of the normal response range of the load current is fixed at zero amperes. The test energy injection will not cause a drop in load current. The threshold adaptive adjustment can match the difference in the test energy response amplitude under different loads, ensuring the consistency of the discrimination standard under light load and heavy load conditions. For example, when the reference voltage recovery threshold is 0.08 volts, the load factor is 0.5, and the voltage correction factor is 0.2, the current operating condition voltage recovery threshold is 0.08 volts multiplied by 1.1, and the calculated result is 0.088 volts.

[0051] After the threshold calculation is completed, the comparison stage is entered. The common output sampling voltage recovery amount in the energy response relationship is compared with the voltage recovery threshold to obtain the voltage discrimination result. The voltage discrimination result is divided into two cases: recovery meets the standard and recovery does not meet the standard. The load current increment is compared with the normal response range of the load current to obtain the current discrimination result. The current discrimination result is divided into two cases: current within the range and current outside the range.

[0052] The two-dimensional judgment results combine to form four judgment scenarios. The first scenario is when the shared output sampling voltage recovery is greater than or equal to the voltage recovery threshold, and the load current increment is within the normal load current response range. In this case, the fault is determined to occur on the main power supply side. The judgment logic is that the energy injected by the backup circuit mainly boosts the output voltage without causing additional current growth, indicating that the load itself has not changed, and the voltage anomaly originates from a decrease in the main power supply capacity. The second scenario is when the shared output sampling voltage recovery is less than the voltage recovery threshold, and the load current increment exceeds the normal load current response range. In this case, the fault is determined to occur on the load side. The judgment logic is that the backup circuit... If the injected energy fails to effectively boost the voltage and causes an abnormal current increase, it indicates that an additional current path has appeared on the load side, and the energy is abnormally consumed by the load side. The third scenario is that the recovery amount of the shared output sampling voltage is greater than or equal to the voltage recovery threshold, and the load current increment exceeds the normal response range of the load current. The fourth scenario is that the recovery amount of the shared output sampling voltage is less than the voltage recovery threshold, and the load current increment is within the normal response range of the load current. The third and fourth scenarios are boundary cases, and the fault type cannot be directly determined. A secondary energy detection process needs to be triggered. The secondary detection uses a larger test energy unit to repeat the detection process, thereby improving the discrimination margin.

[0053] To quantify the reliability of the judgment results, the fault confidence score is calculated. The formula for calculating the fault confidence score of the main road is as follows: in This represents the confidence level of a main road fault, ranging from 0 to positive infinity. A value greater than 1 is considered a high-confidence main road fault. The formula for calculating the load-side fault confidence level is as follows: in This represents the load-side fault confidence level. A value greater than 1 indicates a high-confidence load fault. For example, when the voltage recovery is 0.175 volts, the voltage recovery threshold is 0.088 volts, the load current increment is 0.2 amps, and the upper limit of the current increment is 0.3 amps, the main circuit fault confidence level is approximately [missing value]. The calculated result is 1.5, which belongs to the high-confidence main road fault.

[0054] The fault confidence level is used to adjust the intensity of subsequent processing strategies. The higher the confidence level, the more aggressive the processing action. When a fault is determined to be on the main power supply side, the fault type identifier is recorded as 01, the fault trigger time is recorded as the timestamp corresponding to the current sampling time, and the voltage energy response coefficient and current energy response coefficient in the energy response relationship are recorded. The above data are combined to generate the main power supply side fault result. After the main power supply side fault result is generated, it is sent to the phase control link to trigger the main residual magnetic energy calculation and backup line preset magnetic energy establishment process, preparing for subsequent impact-free switching. When a fault is determined to be on the load side, the fault type identifier is recorded as 02, the fault trigger time is recorded as the timestamp corresponding to the current sampling time, and the load side fault result is generated. As a result, three levels of protection actions are executed simultaneously. The first level action is to disconnect the controlled path between the internal freewheeling circuit of the backup circuit and the common output terminal, cutting off the energy transmission path from the backup circuit to the load side. The second level action is to set the maximum allowable duty cycle of the backup circuit PWM chip to zero and block the backup circuit power transistor drive signal to prevent energy from continuing to accumulate inside the backup circuit. The third level action is to set the load side fault alarm flag and report the fault status to the upper-level control system. The three levels of protection actions are executed step by step to ensure that the backup circuit will not continuously inject energy into the faulty load, avoid the expansion of the fault range, and terminate the switching process after the load side fault result is generated, maintain the main circuit power supply status and wait for manual investigation to prevent the fault from spreading and affecting the backup power module.

[0055] The calculation process of the main circuit residual magnetic energy parameters is used to quantify the remaining energy state of the main circuit output inductor after the duty cycle is reduced, providing a basis for the subsequent backup circuit phase matching and realizing the smooth transfer of the two currents. First, the main circuit PWM duty cycle state of the three PWM cycles before the start of the first detection period and the three PWM cycles after the end of the first detection period is extracted. Combined with the topology and freewheeling path of the main circuit output inductor, the main circuit adopts a buck topology. The freewheeling path includes the output inductor and the freewheeling diode. The current can only flow in one direction. The direction of the residual current of the main circuit output inductor is determined according to the change in polarity of the main circuit feedback before and after the duty cycle is reduced. When the polarity of the feedback is positive, the current flows from the inductor output terminal to the common output terminal, which is recorded as positive. When the polarity of the feedback is negative, the current flows in the reverse direction, which is recorded as reverse. Under normal operating conditions, the direction of the residual current always remains positive, and the freewheeling diode blocks the reverse current path.

[0056] The residual current direction indicator is used for subsequent matching of the preset current direction, ensuring that the preset current direction of the backup circuit is consistent with the residual current direction of the main circuit. After the direction determination is completed, the attenuation trajectory calculation stage begins. The main circuit feedback recovery trajectory is extracted from the dual-source energy response data. The main circuit feedback recovery trajectory contains feedback values ​​at multiple sampling times. The feedback values ​​in the main circuit feedback recovery trajectory are converted into inductor current values ​​according to a preset scaling factor. The scaling factor is determined by the current sampling resistor value and the signal conditioning gain. The conversion formula is as follows: in Representing the The inductor current value corresponding to each sampling point, in amperes. Representing the The main path feedback quantity at each sampling point, in units of volts. This represents the resistance value of the current sampling resistor, with the dimension of ohms. This represents the gain of the signal conditioning circuit and is a dimensionless value.

[0057] After conversion, a discrete sequence of residual current changing with time is obtained. Piecewise linear fitting of the discrete sequence yields the residual current decay trajectory. Under the Buck topology, the inductor current decays linearly during the freewheeling phase. The decay slope is determined by the output voltage, the freewheeling diode voltage drop, and the inductance value. The decay formula is as follows: in The initial value of the inductor current at the moment of decay begins, in amperes. This represents the shared output sampling voltage, measured in volts. This represents the forward voltage drop of a freewheeling diode, measured in volts. The inductance value represents the main output inductance, and its dimension is Henry. This represents the time relative to the start of decay, measured in seconds.

[0058] The least squares method is used to linearly fit the discrete sequence, obtaining two parameters: the initial current value and the decay slope. These two parameters together determine the residual current decay trajectory. For example, when the inductance value is 10 microhenries, the output voltage is 12 volts, and the diode voltage drop is 0.7 volts, the decay slope is approximately -1.27e6 amperes per second. If the initial current is 5 amperes, the time for the current to decay to zero is approximately 3.94 microseconds. The residual current decay trajectory is used to predict the residual current value at any given time, providing a basis for subsequent current matching calculations. After completing the decay trajectory fitting, the release time determination stage begins. The residual magnetic energy release time refers to the inductor voltage... To improve accuracy, a dual-method fusion approach is used to determine the release time when the residual current decays to zero and the magnetic energy is essentially released. The first method is trajectory extrapolation, which calculates the time point corresponding to zero current value based on the fitted residual current decay trajectory as the first release time. The second method is the voltage minimum point method, which extracts the change in the common output sampling voltage during the first detection period and finds the time corresponding to the lowest point of the common output sampling voltage as the second release time. The voltage minimum point corresponds to the moment when the inductor current no longer provides energy to the output. The two times are then weighted and averaged to obtain the final residual magnetic energy release time. The weighting formula is as follows: in Represents the moment when the final residual magnetic energy is released, with the dimension of seconds. The first release moment obtained by the trajectory extrapolation method. The second release time, obtained by the method of minimum voltage point, represents the second release time. and These represent the weighting coefficients of the two methods, and the sum of the weights equals 1. The fusion of the two methods can offset the measurement error of a single method and improve the accuracy of the release time calculation. In addition to the three parameters mentioned above, the initial value of residual magnetic energy is also calculated as a supplementary parameter. The initial value of residual magnetic energy refers to the total magnetic energy stored in the inductor at the start of decay, and the calculation formula is as follows: in The initial value of residual magnetic energy, measured in Joules, guides the setting of the preset magnetic energy in the backup circuit, ensuring energy matching between the two circuits. The residual current direction, residual current decay trajectory, residual magnetic energy release time, and initial value together constitute the main circuit residual magnetic energy parameters. These parameters are sent to the backup circuit pre-charging control stage to control the backup circuit in establishing a matching preset current. Simultaneously, they are sent to the phase calculation stage to determine the optimal time for backup circuit connection.

[0059] The process of establishing the backup circuit's pre-set magnetic energy is completed under the condition that the backup circuit is isolated from the output terminal. It can establish the matching current in advance without affecting the load power supply, preparing for subsequent impact-free connection. After receiving the residual magnetic energy parameters of the main circuit, a wake-up command is sent to the backup circuit PWM chip, causing the backup circuit PWM chip to exit the intermittent standby state and enter the pre-charge working mode. The internal clock and control circuit of the backup circuit are started. The pre-charge working mode refers to the operating mode in which the PWM chip only drives the internal power transistor and the output path remains disconnected. At the same time, the isolation switch between the backup circuit output side and the common output terminal is kept in the open state, so that the backup circuit and the common output terminal maintain controlled isolation and ensure that the backup circuit energy does not flow into the common output terminal during the pre-charge process, avoiding interference to the load voltage.

[0060] After wake-up is complete, the preset current target value is calculated. This preset current target value needs to precisely match the main circuit residual current value at the time of backup circuit access. Considering the continuous decay of the main circuit residual current during the pre-charging process, a time correction is applied to the initial value of the main circuit residual current. The formula for calculating the preset current target value is as follows: in This represents the preset target current value, measured in amperes. This represents the initial value of the residual current in the main circuit, in amperes. This represents the shared output sampling voltage, measured in volts. This represents the forward voltage drop of the main circuit freewheeling diode, measured in volts. This represents the main output inductance value, measured in Henry. This represents the estimated total pre-charging time, measured in seconds.

[0061] Time correction can offset the current difference caused by the natural decay of the main circuit residual current during pre-charging, ensuring that the current values ​​of the two circuits are completely equal at the time of connection. For example, when the initial value of the main circuit residual current is 5 amps, the main circuit decay slope is 1.27e6 amps per second, and the pre-charging time is 10 microseconds, the preset current target value is approximately 5 amps minus 12.7 amps. When the calculation result is negative, it is taken as zero amps, indicating that the main circuit residual current has decayed completely, and the preset current is established from zero. After the target value is calculated, the current ramp-up stage begins. The backup circuit PWM chip is controlled to gradually increase the duty cycle in a variable step size manner, so that the backup circuit output inductor gradually builds current in the internal freewheeling circuit. The duty cycle step size is adaptively adjusted according to the difference between the current and the target value. When the difference is large, a large step size is used to speed up the establishment speed, and when the difference is small, a small step size is used to prevent overshoot. The step size adjustment formula is as follows: in Representing the The duty cycle step size of each adjustment period. This represents the maximum step size, and is a dimensionless value. Representing the The backup circuit inductor current value for each adjustment cycle.

[0062] Duty cycle adjustment is performed once per PWM cycle. The backup circuit feedback is collected in real time and converted into the backup circuit inductor current value. The conversion ratio is consistent with that of the main circuit feedback. When the backup circuit inductor current value reaches 90% of the preset current target value, the open-loop ramp-up mode is exited and the closed-loop fine-tuning mode is entered. Proportional-integral control is used to stabilize the current at the preset current target value, eliminating steady-state error. When the backup circuit inductor current value stabilizes at the preset current target value and the fluctuation range is less than 1% of the target value for three consecutive PWM cycles, the preset current is considered established, the duty cycle adjustment is stopped, and the current duty cycle is maintained. After the preset current is established, relevant parameters are recorded. First, the final value of the preset current is recorded, taking the average of five sampling cycles during the stable phase as the final value. Then, the time when the preset current is established is recorded. Finally, the preset magnetic energy of the backup circuit output inductor is calculated using the following formula: in Represents the preset magnetic energy, with the dimension of joules. The inductance value representing the backup circuit output inductance, expressed in Henry. The final value of the preset current is represented by amperes. Finally, the current duty cycle state of the backup circuit PWM is recorded. The final value of the preset current, the time when the preset current is established, the preset magnetic energy, and the current duty cycle state of the backup circuit PWM are combined to form the backup circuit preset magnetic energy parameter. The backup circuit preset magnetic energy parameter is sent to the phase control link to determine the optimal time for the backup circuit to connect to the common output terminal. The preset current can ensure a smooth transition between the two currents at the moment of connection, avoiding voltage drops or spikes in the output voltage.

[0063] The power transfer process employs a dual-loop control method combining voltage closed-loop and current distribution loops. This ensures smooth load current transfer while maintaining stable output voltage, preventing voltage drops or current surges during the transfer process. After the backup circuit is connected to the common output terminal, the common output sampling voltage is acquired in real time at a preset sampling frequency. The common output sampling voltage is compared with a preset target voltage value to obtain the voltage deviation. The formula for calculating the voltage deviation is as follows: in Representing the The voltage deviation per sampling period, in volts. This represents the preset target voltage value, measured in volts. Representing the The common output sampling voltage for each sampling period, in volts.

[0064] The voltage regulation increment of the backup circuit PWM duty cycle is calculated based on the voltage deviation using a proportional-integral (PI) control algorithm. The PI control formula is as follows: in Representing the The voltage adjustment increment per sampling period is a dimensionless value. This represents the voltage loop proportionality coefficient. This represents the voltage loop integral coefficient, with dimensions per second. This represents the sampling period, measured in seconds.

[0065] The voltage regulation increment is used to correct the output voltage deviation, ensuring that the shared output sampling voltage remains near the target value during the transfer process. For example, when the target voltage is 12 volts, the actual voltage is 11.9 volts, and the voltage proportionality coefficient is 0.1 per volt, the duty cycle increment contributed by the proportional term is 0.01. Current distribution regulation is performed simultaneously with the voltage closed loop, real-time acquisition of the main and backup feedback quantities, and calculation of the amplitude difference in the current main / backup feedback difference data. The amplitude difference reflects the current distribution gap between the two paths. The goal of the current distribution loop is to gradually allow the backup output current to take over the main output current. An S-shaped transfer curve is used to control the transfer rate, with a slower rate at the beginning and end of the transfer and a faster rate in the middle of the transfer to avoid oscillations caused by sudden current changes. The formula for the target value of the current distribution ratio changing over time is... in represent The target current distribution ratio at any given time, i.e., the ratio of backup circuit current to total load current, ranges from 0 to 1. Represents the steepness coefficient of the S-curve. This represents the midpoint of the transition. The current distribution adjustment increment is calculated based on the difference between the current current distribution ratio and the target ratio, using the following formula: in Representing the The current distribution adjustment increment per sampling period is a dimensionless value. Represents the proportionality coefficient of the current distribution ring. This represents the current actual current distribution ratio, obtained by dividing the backup circuit current by the total load current.

[0066] The current distribution adjustment increment is used to control the growth rate of the backup circuit current, making the current transfer process smooth and controllable. The total duty cycle adjustment is obtained by superimposing the voltage adjustment increment and the current distribution adjustment increment, using the following formula: Representing the The total duty cycle adjustment for each sampling period is applied to the two increments before superposition. The voltage regulation increment has a narrow limiting range to ensure that the voltage loop does not excessively interfere with the current distribution process. The current distribution regulation increment's limiting range is determined by the maximum transfer rate to prevent the system from oscillating due to excessively fast current transfer speed.

[0067] The backup circuit PWM duty cycle status is continuously updated based on the total duty cycle adjustment. The duty cycle value is updated once per sampling cycle. During the transfer process, three judgment conditions are continuously monitored. The first condition is that the main circuit feedback quantity is continuously lower than the preset main circuit exit threshold for a duration of a preset stabilization period. The main circuit exit threshold corresponds to the main circuit current being close to zero. The stabilization period is used to confirm that the main circuit has completely exited power supply without recurrence. The second condition is that the shared output sampling voltage is stable within the preset target voltage range, which refers to the range of 2% above and below the target voltage. The third condition is that the current value corresponding to the backup circuit feedback quantity reaches the rated current of the load, indicating that the backup circuit has fully undertaken the entire load. When all three conditions are met, it is determined that the load power supply has been completely transferred from the main circuit to the backup circuit, the transfer adjustment process is stopped, and the backup circuit enters the independent voltage closed-loop power supply mode. After the judgment is completed, the transfer completion flag is set, and the main circuit PWM drive signal is blocked, so that the main circuit completely stops working and waits for fault investigation and recovery.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A backup power supply standby control method based on feedback difference, characterized in that: Includes the following steps: S1. Collect the main feedback quantity, backup feedback quantity, common output sampling voltage, main PWM duty cycle status and load change data. Generate main and backup feedback difference data based on the amplitude difference, rate of change difference and response difference relative to the common output sampling voltage between the main and backup feedback quantities and the backup feedback quantity. Generate energy detection command when the main and backup feedback difference data meet the preset abnormal conditions. S2. According to the energy detection command, maintain the backup circuit in an unsteady state and control the main circuit to reduce the first test energy unit during the first detection period, and the backup circuit to inject the second test energy unit during the second detection period. The absolute values ​​of the first test energy unit and the second test energy unit are equal. Obtain the common output sampling voltage change, load current increment, main circuit feedback recovery trajectory and backup circuit feedback response trajectory in the two periods respectively to form dual-source energy response data. S3. Determine the energy response relationship between the recovery amount of the common output sampling voltage and the increment of the load current corresponding to the second test energy unit based on the dual-source energy response data. When the second test energy unit restores the common output sampling voltage and the increment of the load current is within the normal response range, generate a fault result on the main power supply side. When the common output sampling voltage is not restored and the increment of the load current exceeds the normal response range, generate a fault result on the load side and limit the energy injected into the backup circuit. S4. Based on the fault results of the main power supply side, according to the duty state of multiple PWM cycles before and after the first detection period of the main road, the main road feedback recovery trajectory and the change of the common output sampling voltage, determine the direction of the residual current of the main output inductor, the residual current decay trajectory and the time of residual magnetic energy release, generate the main road residual magnetic energy parameters, and control the backup PWM chip to exit intermittent standby, establish a preset current in the internal freewheeling circuit of the backup road and the common output terminal under controlled isolation, and generate the backup road preset magnetic energy parameters. S5. Determine the control phase of the backup circuit connected to the common output terminal based on the residual magnetic energy parameters of the main circuit and the preset magnetic energy parameters of the backup circuit. Control the backup circuit to release the preset magnetic energy in the control phase so that the attenuation of the residual current of the main circuit matches the increase of the output current of the backup circuit. Continuously adjust the PWM duty cycle of the backup circuit based on the common output sampling voltage and the main / backup feedback difference data until the load power supply is transferred from the main circuit to the backup circuit.

2. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The specific process for generating primary / backup feedback difference data is as follows: In each sampling period, the instantaneous values ​​of the main path feedback quantity and the backup path feedback quantity are collected synchronously. The amplitude difference between the main path feedback quantity and the backup path feedback quantity at the same sampling moment is calculated and the absolute value is taken to obtain the amplitude difference quantity. Within a preset sliding time window, calculate the rate of change of the main path feedback quantity and the backup path feedback quantity per unit time, and obtain the difference between the rate of change of the main path feedback quantity and the backup path feedback quantity per unit time to obtain the rate of change difference. The moment when the shared output sampling voltage undergoes a step change is used as the reference time. The response delay and steady-state response amplitude deviation of the main feedback quantity relative to the reference time, as well as the response delay and steady-state response amplitude deviation of the backup feedback quantity relative to the reference time, are calculated and denoted as main response delay, backup response delay, main steady-state response amplitude deviation, and backup steady-state response amplitude deviation, respectively. The difference between the main response delay and the backup response delay, and the difference between the main steady-state response amplitude deviation and the backup steady-state response amplitude deviation are combined to form the response difference quantity. The amplitude difference quantity, the rate of change difference quantity, and the response difference quantity together constitute the main and backup feedback difference data.

3. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The specific process for generating energy detection commands is as follows: Pre-set amplitude difference threshold, rate of change difference threshold, and response difference threshold. Compare the amplitude difference in the master and backup feedback difference data with the amplitude difference threshold, the rate of change difference with the rate of change difference threshold, and the response difference with the response difference threshold. An abnormal timer is initiated when the amplitude difference exceeds the amplitude difference threshold, the rate of change difference exceeds the rate of change difference threshold, or the response difference exceeds the response difference threshold. If the cumulative duration of abnormal timing reaches the preset abnormal duration and the corresponding difference remains above the corresponding threshold throughout the abnormal duration, an energy detection command will be generated.

4. The backup power supply standby control method based on feedback difference according to claim 2, characterized in that: The backup circuit PWM chip maintains an intermittent standby state, the internal freewheeling circuit of the backup circuit remains on, and the isolation switch between the backup circuit output side and the common output terminal remains off, so that the backup circuit does not continuously output energy to the common output terminal, and only maintains the minimum operating state of the internal circuit of the backup circuit. Upon receiving the energy detection command, the duty cycle of the main PWM is reduced at the start of the first detection period, so that the output energy of the main circuit during the first detection period is reduced by a first test energy unit relative to the current steady-state output energy. The first test energy unit is a preset proportion of the current single-cycle output energy of the main circuit. The duty cycle reduction is completed within a single PWM cycle. The first detection period covers at least three complete PWM cycles. Immediately after the first detection period ends, the second detection period begins. The controlled path between the internal freewheeling circuit of the backup circuit and the common output terminal is closed, so that the energy stored in the inductor inside the backup circuit is released to the common output terminal as a second test energy unit. The absolute value of the energy of the second test energy unit is equal to that of the first test energy unit. The controlled path is immediately disconnected after the energy injection is completed. The duration of the second detection period is equal to that of the first detection period.

5. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The specific process of generating dual-source energy response data is as follows: During the first detection period, the instantaneous values ​​of the shared output sampling voltage, load current, and main feedback quantity are continuously collected at a preset sampling frequency. The shared output sampling voltage at the beginning of the first detection period is used as the reference value. The difference between the shared output sampling voltage at the end of the first detection period and the reference value is calculated to obtain the voltage change in the first period. The difference between the maximum load current in the first detection period and the load current at the beginning is calculated to obtain the load current increment in the first period. All main feedback quantity sampling points in the first detection period are arranged in chronological order to form the main feedback recovery trajectory. During the second detection period, the instantaneous values ​​of the common output sampling voltage, load current, and backup circuit feedback quantity are continuously collected at the same sampling frequency. Taking the common output sampling voltage at the beginning of the second detection period as the reference value, the difference between the common output sampling voltage at the end of the second detection period and the reference value is calculated to obtain the voltage change in the second period. The difference between the maximum load current in the second detection period and the load current at the beginning is calculated to obtain the load current increment in the second period. All backup circuit feedback quantity sampling points in the second detection period are arranged in chronological order to form the backup circuit feedback response trajectory. The voltage change in the first time period, the load current increment in the first time period, the main feedback recovery trajectory, the voltage change in the second time period, the load current increment in the second time period, and the backup feedback response trajectory are combined to form dual-source energy response data.

6. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The specific process for determining the energy response relationship is as follows: The voltage change in the first time period and the voltage change in the second time period are extracted from the dual-source energy response data. The absolute value of the voltage change in the first time period is used as the voltage drop reference value. The voltage change in the second time period is added to the voltage drop reference value to obtain the common output sampling voltage recovery amount. The load current increment in the second time period is extracted from the dual-source energy response data. The energy value of the second test energy unit is used as the reference. The ratio of the common output sampling voltage recovery amount to the second test energy unit is calculated to obtain the voltage energy response coefficient. The ratio of the load current increment to the second test energy unit is calculated to obtain the current energy response coefficient. The common output sampling voltage recovery amount, the load current increment, the voltage energy response coefficient, and the current energy response coefficient are combined to form the energy response relationship corresponding to the second test energy unit.

7. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The voltage recovery threshold and the normal response range of the load current are preset. The common output sample voltage recovery amount in the energy response relationship is compared with the voltage recovery threshold, and the load current increment is compared with the normal response range of the load current. When the recovery amount of the shared output sampling voltage is greater than or equal to the voltage recovery threshold, and the load current increment is within the normal response range of the load current, it is determined that the fault occurred on the main power supply side. The fault type identifier, fault trigger time and corresponding energy response coefficient are recorded, and the fault result of the main power supply side is generated. When the recovery amount of the common output sampling voltage is less than the voltage recovery threshold and the load current increment exceeds the normal response range of the load current, it is determined that the fault occurs on the load side, the fault type identifier and the fault trigger time are recorded, the load side fault result is generated, and the controlled path between the internal freewheeling circuit of the backup circuit and the common output terminal is disconnected. The maximum allowable duty cycle of the backup circuit PWM chip is set to zero so that the backup circuit cannot continue to inject energy into the common output terminal.

8. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: The specific process for generating the residual magnetic energy parameters of the main circuit is as follows: Extract the main PWM duty cycle state of the three PWM cycles before the start of the first detection period and the three PWM cycles after the end of the first detection period. Combine the topology and freewheeling path of the main output inductor and determine the direction of the residual current of the main output inductor based on the polarity change of the main feedback before and after the duty cycle is reduced. The main feedback recovery trajectory is extracted from the dual-source energy response data. The feedback values ​​in the main feedback recovery trajectory are converted into inductor current values ​​according to a preset proportional coefficient to obtain a discrete sequence of residual current changing with time. An exponential function is fitted to the discrete sequence to obtain the residual current decay trajectory. The change in the common output sampling voltage during the first detection period is extracted. The moment when the common output sampling voltage drops to its lowest point is found. This moment is taken as the residual magnetic energy release moment when the residual magnetic energy of the main output inductor is completely released. The residual current direction, residual current decay trajectory, and residual magnetic energy release moment are combined to form the main residual magnetic energy parameters.

9. The backup power supply standby control method based on feedback difference according to claim 7, characterized in that: The specific process for generating the preset magnetic energy parameters for the backup path is as follows: Upon receiving the residual magnetic energy parameters of the main circuit, a wake-up command is sent to the backup circuit PWM chip, causing the backup circuit PWM chip to exit the intermittent standby state and enter the pre-charge working mode. The internal clock and control loop of the backup circuit are started, while the isolation switch between the backup circuit output side and the common output terminal is kept open, so that the backup circuit and the common output terminal are kept under controlled isolation. The backup circuit PWM chip is controlled to gradually increase the duty cycle according to the preset step size, so that the backup circuit output inductor gradually builds current in the internal freewheeling circuit. The preset current target value is set according to the initial value of the residual current in the main circuit residual magnetic energy parameters. The feedback quantity of the backup circuit is collected in real time and converted into the backup circuit inductor current value. When the backup circuit inductor current value reaches the preset current target value, the increase of the duty cycle is stopped and the current duty cycle is maintained. The final value of the preset current, the time when the preset current is built up, the preset magnetic energy of the backup circuit output inductor, and the current duty cycle state of the backup circuit PWM are recorded, and together they form the preset magnetic energy parameters of the backup circuit.

10. The backup power supply standby control method based on feedback difference according to claim 1, characterized in that: Extract the residual current decay trajectory and residual magnetic energy release time from the residual magnetic energy parameters of the main line, extract the preset current value and preset magnetic energy from the preset magnetic energy parameters of the backup line, take the time point when the residual current value on the residual current decay trajectory of the main line is equal to the preset current value of the backup line as the reference point, and set the time corresponding to the reference point as the takeover phase of the backup line access to the common output terminal. When the takeover phase is reached, the isolation switch between the backup output side and the common output terminal is closed, and the backup PWM chip is controlled to adjust the duty cycle according to the preset switching slope, so that the preset magnetic energy stored in the backup output inductor is gradually released to the common output terminal. The feedback quantities of the main circuit and the backup circuit are collected in real time and converted into the attenuation of the residual current of the main circuit and the increase of the output current of the backup circuit, respectively. The adjustment rate of the PWM duty cycle of the backup circuit is dynamically adjusted according to the real-time attenuation rate of the residual current of the main circuit, so that the attenuation of the residual current of the main circuit and the increase of the output current of the backup circuit remain equal in value in each sampling period, and the total current of the shared output terminal remains continuous without sudden changes.

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