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CN-122026708-A - Parallel power supply system based on feedback injection and current sharing method

CN122026708ACN 122026708 ACN122026708 ACN 122026708ACN-122026708-A

Abstract

The invention relates to the technical field of electric energy conversion, in particular to a parallel power supply system based on feedback injection and a current sharing method. The system comprises a plurality of power conversion branches, a central current sharing controller and a current detection circuit. Each branch circuit comprises a power management unit, an active isolation circuit and a feedback regulation network. The controller collects current and change rate in real time, and injects analog compensation signals into the branch voltage feedback pins through the feedback network, and adjusts output voltage under the condition of not changing internal references of the chip, so that load current dynamic balance is realized. When the current change rate of any power supply conversion branch circuit exceeds the early warning threshold value, a derating signal is generated to control the derating signal to reduce the current proportion, so that the derating signal operates in an on-line derating mode. In addition, the invention also provides a current equalizing method applied to the parallel power supply system. The invention realizes non-invasive accurate regulation and control, effectively prolongs the service life of the system and ensures the service continuity by actively derating to protect the sub-health module.

Inventors

  • LIU JIAWEI
  • SU ZHONGLIANG
  • WANG JIANHUI

Assignees

  • 南宁初芯集成电路设计有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (9)

  1. 1. The parallel power supply system based on feedback injection is characterized by comprising a direct current input bus and a direct current output bus, a plurality of power conversion branches connected in parallel between the direct current input bus and the direct current output bus, a central current sharing controller (4) and a current detection circuit (5) connected with the central current sharing controller (4), wherein each power conversion branch comprises: a power management unit (1) having a voltage feedback pin for regulating an output voltage; the active isolation circuit is connected in series between the output end of the power management unit (1) and the direct current output bus and is used for controlling the switching of the branch and preventing reverse current; A feedback regulation network connected between the central current-sharing controller (4) and the voltage feedback pins, configured to inject an analog compensation signal output by the central current-sharing controller (4) into the voltage feedback pins so as to regulate the output voltage of the power management unit (1) without changing the internal reference standard thereof; The central current sharing controller (4) is configured to execute the following self-adaptive current sharing and protection logic, wherein the current detection circuit (5) is used for collecting the output current value and the current change rate of each branch in real time, calculating the deviation between the output current value of each branch and the average current value of the system, injecting differentiated analog compensation voltage into the voltage feedback pins of each branch through the feedback adjustment network based on the deviation and the current change rate so as to adjust the equivalent output impedance of each branch to realize the dynamic balance of load current, and generating a derating control signal to be overlapped into the analog compensation voltage when the current change rate of any power conversion branch exceeds a preset trend early warning threshold value to control the power conversion branch to reduce the output current sharing proportion of the power conversion branch so as to enable the power conversion branch to be in an on-line derating operation state.
  2. 2. The feedback injection-based parallel power supply system of claim 1, wherein the feedback conditioning network comprises: A digital-to-analog converter (6) with a digital input connected to the control bus of the central current-sharing controller (4); The signal conditioning circuit (3) is connected to the analog output end of the digital-to-analog converter (6) and is used for carrying out impedance matching and filtering on the analog compensation signal; One end of the injection resistor (2) is connected to the output end of the signal conditioning circuit (3), and the other end of the injection resistor is directly connected to the voltage feedback pin of the power management unit (1); The central current sharing controller (4) controls injection current flowing through the injection resistor (2) by adjusting the output amplitude of the digital-to-analog converter (6), and the injection current is overlapped with partial pressure feedback current in the power management unit (1), so that the closed loop adjustment target of the power management unit (1) is linearly offset.
  3. 3. The feedback injection based parallel power supply system according to claim 1, characterized in that the central current sharing controller (4) is configured with a dual closed loop control architecture, an inner loop is a high bandwidth voltage control loop of the power management unit (1) itself for responding to transient load changes, an outer loop is a low bandwidth current sharing control loop constructed by the central current sharing controller (4), the control bandwidth of which is configured to be lower than one tenth of the bandwidth of the high bandwidth voltage control loop to avoid oscillation caused by loop competition, the adaptive current sharing and protection logic is operated in the outer loop, and steady state operating points of each branch are set by adjusting the direct current component of the analog compensation signal.
  4. 4. The feedback injection based parallel power supply system according to claim 1, characterized in that the active isolation circuit comprises an isolation switch (71) equipped with a backflow prevention driver (72), the power management unit (1) is provided with an enable pin, the central current sharing controller (4) is further configured to implement a multistage fault response strategy: The L1 level response is that when the current change rate of any power conversion branch is between the trend early warning threshold value and the hard fault threshold value, the on-line derating operation state is executed, and the isolation switch (71) is maintained to be conducted; L2 stage response, namely when any power conversion branch circuit logic state abnormality is monitored and the current change rate does not reach the hard fault threshold value, pulling down an enabling pin of the branch circuit power management unit (1) to execute soft reset operation, and pulling up the enabling pin again after preset cooling time; And the L3 level responds that when the current change rate of any power conversion branch reaches the hard fault threshold value, an off instruction is sent to the anti-backflow driver (72), the isolating switch (71) is controlled to be cut off, the branch is physically isolated from the direct current output bus, after the physical isolation is carried out, the electrical characteristics of the isolating branch are periodically detected, and if the characteristics are restored to a safe interval, the isolating switch (71) is controlled to enter a soft start mode to be connected again.
  5. 5. The feedback injection-based parallel power supply system of claim 1, wherein the central current sharing controller (4) determines the magnitude of the derating control signal by building a key device aging characteristic model for each branch, the model mapping the current change rate to a health coefficient of the device, calculating an asymmetric current sharing weight according to the health coefficient, assigning a smaller current sharing weight to a branch with a lower health coefficient, calculating a target current value for each branch based on the asymmetric current sharing weight, and back-pushing the required analog compensation voltage.
  6. 6. A parallel power supply system based on feedback injection as claimed in claim 1, characterized in that the current detection circuit (5) comprises a low-resistance sampling resistor connected in series on each branch output path and a differential amplifier connected across the sampling resistor, the output of the differential amplifier being connected to the analog-to-digital conversion interface of the central current sharing controller (4).
  7. 7. A current equalizing method applied to the parallel power supply system based on feedback injection as claimed in any one of claims 1 to 6, comprising the steps of: s1, collecting output current values of all power supply conversion branches in real time; S2, calculating a dynamic operation parameter of the output current value, wherein the dynamic operation parameter at least comprises a current change rate; s3, comparing the dynamic operation parameters with preset safety reference values, and evaluating the operation grade of each branch; s4, when a certain branch is estimated to be in an early warning operation level, calculating an asymmetric current sharing target value of the branch so as to reduce the output current sharing proportion; s5, calculating an analog compensation voltage value through a PI control algorithm according to the deviation of the actual current value and the asymmetric current sharing target value, injecting the analog compensation voltage value into a voltage feedback pin of a corresponding branch, and adjusting the equivalent output impedance of the power conversion branch to enable the current of the power conversion branch to be converged to the asymmetric current sharing target value.
  8. 8. The current sharing method according to claim 7, wherein the step S1 further includes collecting output voltage signals of each power conversion branch in real time, the step S2 further includes performing frequency domain analysis on the collected output voltage signals, extracting amplitude variation at a switching frequency as a ripple frequency domain amplitude parameter, and the step S3 further includes determining that the branch filter capacitor is aged and correspondingly reducing current sharing weight of the branch when the ripple frequency domain amplitude parameter is detected to exceed a preset threshold.
  9. 9. The current sharing method according to claim 7, further comprising a fault isolation and self-healing step of immediately controlling the active isolation circuit of the power conversion branch to be disconnected when detecting that the reverse current of any power conversion branch exceeds a preset reverse current threshold or a dynamic operation parameter reaches a hard fault threshold, continuously monitoring the recovery condition of the isolated port voltage of the power conversion branch during the isolation period, and controlling the active isolation circuit of the power conversion branch to enter a current-limiting soft start mode to be re-integrated into a direct current output bus by gradually increasing the conduction angle if the port voltage is recovered to a normal range.

Description

Parallel power supply system based on feedback injection and current sharing method Technical Field The invention relates to the technical field of electric energy conversion, in particular to a parallel power supply system based on feedback injection and a current sharing method. Background With the rapid development of new energy industry, in power supply and distribution scenes such as direct current micro-grid, high-capacity battery Energy Storage System (ESS), high-power direct current fast charging of electric vehicles and the like, the requirements on high power density and high reliability of the power supply network are increasingly severe. In order to meet the requirements of large current output, dynamic load balancing and system redundancy design, a distributed power distribution architecture adopting a plurality of power conversion modules for parallel power supply has become a mainstream scheme. However, in practical new energy engineering application, the existing parallel power supply system is limited by a complex wide-temperature running environment and a long-period high-load working condition, and the existing parallel power supply system still faces the following technical bottlenecks: first, load distribution imbalance caused by device parameter variability. The reference voltage among parallel branches objectively has millivolt level fine deviation under the restriction of the semiconductor manufacturing process. In a traditional current-sharing power distribution architecture, a branch with a slightly higher output voltage set value tends to bear excessive load current, so that local thermal stress concentration is easily caused and ageing of power devices and filter capacitors is accelerated under a high-power continuous operation scene, a wooden barrel effect is generated, and the Mean Time Between Failure (MTBF) of a power distribution system is remarkably reduced. Second, the dynamic stability problem caused by multiple control loop nesting. If the control bandwidth of the external power distribution regulating loop introduced for realizing current sharing is overlapped with the inherent high-speed voltage feedback loop in the power supply in a frequency domain, loop competition and dynamic conflict are extremely easy to occur, and voltage oscillation or output instability is generated when the power supply system is switched in the face of micro-grid load transient or energy storage charge-discharge state. Third, there is a lack of active management mechanisms for power branch performance degradation. Most of the existing protection logics are based on passive triggering of fixed threshold values, and effective on-line monitoring and intervention means are lacking for early failure characteristics such as filter capacitor aging or heat dissipation environment deterioration. In a new energy critical task scene, if the output current proportion of the branch circuit cannot be actively regulated in the early stage of the degradation of the branch circuit entering state to realize derating operation, the hidden trouble rapidly evolves into destructive failure, and the extremely high requirements of the power supply network on the continuity of the power service and the self-healing of the system are difficult to meet. Disclosure of Invention Accordingly, an objective of the present invention is to provide a parallel power supply system based on feedback injection, so as to solve the above-mentioned problems in the prior art. The second objective of the present invention is to provide a current equalizing method applied to the parallel power supply system based on feedback injection. In order to achieve the first object, the present invention provides the following technical solutions: A parallel power supply system based on feedback injection comprises a direct current input bus and a direct current output bus, a plurality of power conversion branches connected in parallel between the direct current input bus and the direct current output bus, a central current sharing controller and a current detection circuit connected with the central current sharing controller, wherein each power conversion branch comprises: a power management unit having a voltage feedback pin for adjusting an output voltage; the active isolation circuit is connected in series between the output end of the power management unit and the direct current output bus and is used for controlling switching of the branch and preventing reverse current; a feedback regulation network connected between the central current-sharing controller and the voltage feedback pin and configured to inject an analog compensation signal output by the central current-sharing controller into the voltage feedback pin so as to regulate the output voltage of the power management unit without changing the internal reference standard of the power management unit; the central current sharing controller is configured to execute the following sel