Digital current sharing method and device for power supply system and power supply system

Abstract

The invention provides a digital current sharing method and device for a power supply system and the power supply system, and belongs to the technical field of power supplies, the power supply system comprises a plurality of power supply modules which are connected in parallel and adopt droop current sharing, and the method comprises the following iterative operations: in a current current sharing period, determining a load current value of each power supply module, obtaining a plurality of load current values, and calculating to obtain an average value of the plurality of load current values; for each power supply module, calculating an output voltage compensation value of the power supply module corresponding to the load current value under the condition that the absolute value of the difference value between the average value and the load current value of each power supply module is determined to be greater than the absolute value of a preset current bias threshold value, the output voltage compensation value is used for indicating the power supply module corresponding to the load current value to adjust the output voltage. On the basis of not increasing extra lines, the output voltage of each power supply module is adjusted, and the current sharing precision among the power supply modules is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power supplies, and more specifically, to a digital current sharing method, device, and power supply system for a power supply system. Background Art

[0002] In the field of communication power supplies, using multiple power modules in parallel to achieve high-power output is a very important technology. Parallel power supplies have advantages such as centralized management of power supply, easy expansion, good compatibility, redundant backup, high reliability, and high cost performance. Moreover, due to their powerful advantages, they have radiated and promoted the research, progress, and development of the entire power supply field in the technology of parallel power modules. The parallel power supply technology has become the core technology of high-power distributed power supply systems, and the core of realizing parallel operation of power supplies is the current sharing technology.

[0003] The current sharing technology refers to measures for evenly distributing the load current of each power module in a system with n parallel power modules, requiring each module to be able to withstand the self-balancing of current, and at the same time keep the output voltage stable when the input voltage and load current change, and have good current sharing accuracy and transient response.

[0004] Currently, for the current sharing problem between the parallel outputs of multiple power modules, usually two solutions are adopted. Among them, the first solution is active current sharing, that is, by converting the output current of the local machine into a voltage signal and outputting it on the current sharing bus, the current sharing bus displays the current of the machine with the highest current among the current outputs, and then the power module adjusts the output by sampling the voltage of the current sharing bus to achieve current sharing. Since it requires an additional special line to generate the current sharing bus, there is a relatively complex problem in circuit design. The second solution is passive current sharing. Through droop current sharing, the output voltage decreases as the output current increases, satisfying Vo = Vref – k * Iout, where k is usually a constant, that is, equivalent to adding a virtual resistor at the output to achieve current sharing. Due to the high requirements for the sampling accuracy of the output voltage and output current, there will be an error in the output current caused by the voltage error, which will further lead to a relatively large current sharing deviation. Summary of the Invention

[0005] Aiming at the problems in the prior art, based on droop current sharing, the present application provides a digital current sharing method, device, and power supply system for a power supply system, which effectively improves the current sharing accuracy among power modules without adding additional lines.

[0006] In a first aspect, the present application provides a digital current sharing method for a power supply system. The power supply system includes multiple power modules connected in parallel and adopting droop current sharing. The digital current sharing method for the power supply system includes the following iterative operations:

[0007] During the current current sharing period, determine the load current value of each of the power modules to obtain a plurality of the load current values, and calculate the average value of the plurality of the load current values;

[0008] For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each of the power modules is greater than the absolute value of a preset current bias threshold, calculate the output voltage compensation value of the power module corresponding to the load current value, where the output voltage compensation value is used to instruct the power module corresponding to the load current value to adjust the output voltage.

[0009] In some optional implementations of this embodiment, the power system further includes a communication data processing module, and the digital current sharing method for the power system further includes:

[0010] Determine the calculation frequency for performing current sharing processing on each of the power modules according to the communication frequency, where the communication frequency is used to indicate the frequency at which the communication data processing module completes one round of communication with all the power modules;

[0011] Determine the current sharing period according to the calculation frequency, where the communication frequency is greater than the calculation frequency.

[0012] In some optional implementations of this embodiment, the power module includes an output voltage and current sampling circuit and a low-pass filter;

[0013] The determination of the load current value of each of the power modules includes:

[0014] The output voltage and current sampling circuit samples the output current value of each of the power modules to obtain a plurality of sampled current values;

[0015] The low-pass filter performs filtering processing on the plurality of sampled current values to calculate the load current value of each of the power modules.

[0016] In some optional implementations of this embodiment, the low-pass filter performing filtering processing on the plurality of sampled current values includes:

[0017] Determine the filtering frequency threshold for the low-pass filter to perform filtering processing on the plurality of sampled current values according to the communication frequency and the calculation frequency;

[0018] Wherein, the filtering frequency threshold is positively correlated with the communication frequency; the filtering frequency threshold is greater than the calculation frequency and the filtering frequency threshold is less than the communication frequency, and the filtering frequency threshold is used to indicate the maximum frequency that can pass through the low-pass filter.

[0019] In some alternative embodiments of the present embodiment, calculating the average value of the plurality of load current values includes:

[0020] Each power module sends its own load current value to the communication data processing module;

[0021] The communication data processing module generates the average value of the load current values of all the power modules according to the load current value of each power module.

[0022] In some alternative embodiments of the present embodiment, the preset current bias threshold includes a first current bias threshold and a second current bias threshold;

[0023] For each power module, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of the preset current bias threshold, calculating the output voltage compensation value of the power module corresponding to the load current value includes:

[0024] When the communication data processing module determines that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the communication data processing module calculates the first output voltage compensation value of the power module corresponding to the load current value, where the first output voltage compensation value includes a first adjustment voltage, and the first output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage according to the first adjustment voltage;

[0025] When the communication data processing module determines that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the communication data processing module calculates the second output voltage compensation value of the power module corresponding to the load current value, where the second output voltage compensation value includes a second adjustment voltage, and the second output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage according to the second adjustment voltage;

[0026] Wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

[0027] In some alternative embodiments of the present embodiment, the preset current bias threshold includes a first current bias threshold and a second current bias threshold;

[0028] Each power module further includes a controller;

[0029] For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculating an output voltage compensation value for the power module corresponding to the load current value includes:

[0030] The communication data processing module sends the average value to each of the power modules;

[0031] When it is determined in each power module that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the controller of each power module calculates a third output voltage compensation value for the power module corresponding to the load current value, where the third output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage;

[0032] When it is determined in each power module that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the controller of each power module calculates a fourth output voltage compensation value for the power module corresponding to the load current value, where the fourth output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage;

[0033] Wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

[0034] In some alternative ways of this embodiment, each power module and the communication data processing module perform data transmission through an I2C bus, an SPI bus, or an RS485 bus.

[0035] In some alternative ways of this embodiment, determining the load current value of each power module, obtaining a plurality of the load current values, and calculating an average value of the plurality of the load current values includes:

[0036] Each power module samples its own current value to generate its own first load current value;

[0037] Each power module receives second load current values of each power module sent by at least one of the power modules through broadcasting, obtains a plurality of second load current values, and generates an average value of the first load current value and the plurality of second load current values based on the plurality of second load current values and the first load current value.

[0038] In some alternative ways of this embodiment, the preset current bias threshold includes a first current bias threshold and a second current bias threshold;

[0039] Each of the power modules further includes a controller;

[0040] For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculating an output voltage compensation value for the power module corresponding to the load current value includes:

[0041] When it is determined in each power module that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the controller of each power module calculates a fifth output voltage compensation value for the power module corresponding to the load current value, where the fifth output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage;

[0042] When it is determined in each power module that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the controller of each power module calculates a sixth output voltage compensation value for the power module corresponding to the load current value, where the sixth output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage;

[0043] Wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

[0044] In some alternative embodiments of the present embodiment, data transmission is performed between each of the power modules through a CAN bus.

[0045] In a second aspect, the present application provides a digital current sharing device for a power supply system, wherein the power supply system includes a plurality of power modules connected in parallel and adopting droop current sharing, and the digital current sharing device is configured to perform the following iterative operations:

[0046] In the current current sharing period, determine the load current value of each power module, obtain a plurality of the load current values, and calculate the average value of the plurality of the load current values;

[0047] For each power module, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculate an output voltage compensation value for the power module corresponding to the load current value, where the output voltage compensation value is used to instruct the power module corresponding to the load current value to adjust the output voltage.

[0048] In a third aspect, the present application provides a power supply system, including a communication line, a load module, and the digital current sharing device of the foregoing embodiment.

[0049] In view of the problems in the prior art, the digital current sharing method and power supply system for a power supply system provided in this application determine the load current value of each power supply module within the current current sharing period, obtain multiple load current values, and calculate the average value of the multiple load current values; for each power supply module, when it is determined that the absolute value of the difference between the load current value and the average value is greater than the absolute value of a preset current bias threshold, calculate the output voltage compensation value of the power supply module corresponding to the load current value, where the output voltage compensation value is used to instruct the power supply module corresponding to the load current value to adjust the output voltage, so that it is possible to adjust the output voltages of each power supply module in a digital communication manner without adding additional lines, thereby improving the current sharing accuracy among the power supply modules. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1 Structural schematic diagram of the power supply system according to the embodiment of this application;

[0052] Figure 2 Structural schematic diagram of the power supply module according to the embodiment of this application;

[0053] Figure 3 Flowchart of a digital current sharing method for a power supply system according to the embodiment of this application;

[0054] Figure 4 Schematic diagram of calculating the average value of load current values according to the embodiment of this application;

[0055] Figure 5 Method flowchart for determining the current sharing period according to the embodiment of this application;

[0056] Figure 6 Method flowchart for calculating the load current value according to the embodiment of this application;

[0057] Figure 7 Method flowchart for calculating the average value of load current values according to the embodiment of this application;

[0058] Figure 8 One of the method flowcharts for adjusting the compensation value of the output voltage compensation according to the embodiment of this application;

[0059] Figure 9 Schematic diagram of the communication data processing module adjusting the compensation value of the output voltage compensation according to the embodiment of this application;

[0060] Figure 10 This is the second flowchart of the method for adjusting the compensation value of the output voltage compensation in the embodiment of the present application;

[0061] Figure 11 This is a schematic diagram of the controller of the power supply in the embodiment of the present application for adjusting the compensation value of the output voltage compensation;

[0062] Figure 12 This is the third flowchart of the method for adjusting the compensation value of the output voltage compensation in the embodiment of the present application;

[0063] Figure 13 This is a schematic diagram of the structure of a digital current sharing device for a power supply system in the embodiment of the present application. Detailed implementation manners

[0064] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0065] Figure 1 Shows a schematic diagram of the structure of a power supply system according to an embodiment of the present application. As Figure 1 shown, the power supply system includes a communication line, a load module, a plurality of power supply modules connected in parallel and adopting droop current sharing, and a digital current sharing device. It should be understood that the power supply modules and the digital current sharing device are connected through the communication line and establish a communication transmission relationship. Among them, the plurality of power supply modules connected in parallel are such as Figure 1 the power supply module 1, power supply module 2, power supply module 3... power supply module n shown; data can be transmitted between the power supply module and the digital current sharing device through a communication protocol. Among them, the communication protocol includes but is not limited to the I2C bus protocol, CAN bus protocol, RS-485 serial bus protocol, and SPI protocol.

[0066] Further refer to Figure 2, the digital current sharing device may further include a communication data processing module. The power supply module includes an output voltage and current sampling circuit, a low-pass filter, and a controller. Among them, the output voltage and current sampling circuit is used to sample the current output by the power supply module x within a period of time to obtain a plurality of sampled current values, and transmit the sampled output current Iout to the low-pass filter; the low-pass filter is used to output the average output current of the power supply module x during this period, also known as the load current value Iout_Filter x, after receiving the plurality of sampled current values Iout during this period, and report the load current value Iout_Filter x to the communication data processing module through the communication port Com; the controller is used to adjust the output voltage of the voltage module according to the output voltage compensation value Vcomp x of the power supply module x.

[0067] It should be understood that the structures of the power supply modules connected in parallel are the same, that is, they all include Figure 2 the output voltage and current sampling circuit, low-pass filter, and controller shown, and each power supply module is communicatively connected to the communication data processing module through a communication line.

[0068] Figure 3 FIG. is a schematic flowchart of a digital current sharing method for a power supply system according to an embodiment of the present application. The digital current sharing method for a power supply system includes the following iterative operations:

[0069] Step 101: In the current current sharing period, determine the load current value of each power supply module to obtain a plurality of the load current values, and calculate the average value of the plurality of the load current values;

[0070] Step 102: For each power supply module, when it is determined that the absolute value of the difference between the average value and the load current value of each power supply module is greater than the absolute value of a preset current bias threshold, calculate the output voltage compensation value of the power supply module corresponding to the load current value, where the output voltage compensation value is used to instruct the power supply module corresponding to the load current value to adjust the output voltage.

[0071] Aiming at the problems in the prior art, the digital current sharing method for a power supply system provided by the present application can adjust and control the voltage compensation values of each power supply module in a digital communication manner without adding additional lines, thereby stabilizing the output voltage and improving the current sharing accuracy among the power supply modules.

[0072] The following Figure 3 steps 101 to 102 will be described in detail respectively:

[0073] Step 101: During the current current sharing period, determine the load current value of each power module to obtain multiple load current values, and calculate the average value of the multiple load current values.

[0074] In a specific embodiment, the power supply system further includes a communication data processing module. The communication data processing module and each power module perform data transmission through an I2C bus, an SPI bus, or an RS485 bus. And as can be known from the foregoing, the low-pass filter of each power module will calculate the load current value of the power module over a period of time and report the load current value to the communication data processing module. The communication data processing module further calculates the average value of the load current values based on all the received load current values of the power modules. As Figure 4 shown, the load current value of power module 1 is Iout_Filter 1, the load current value of power module 2 is Iout_Filter2... the load current value of power module n is Iout_Filter n. The communication data processing module can calculate the average value Iout_avg of the multiple load current values based on the multiple received load current values: Iout_Filter 1, Iout_Filter 2... Iout_Filter n.

[0075] In this embodiment, taking one current sharing period as a unit, calculate the output voltage compensation value of each power module corresponding to the load current value, and further refer Figure 5 , the method for determining the current sharing period includes:

[0076] Step 103: According to the communication frequency, determine the calculation frequency for performing current sharing processing on each power module, where the communication frequency is used to indicate the frequency at which the communication data processing module completes one round of communication with all the power modules.

[0077] It should be noted that the communication frequency is used to indicate the frequency at which the communication data processing module completes one round of communication with all the power modules, that is, the frequency at which the communication data processing module obtains the load current value of the first power module to the load current value of the last power module and outputs the average value is used as the communication frequency.

[0078] In this embodiment, the calculation frequency of the current sharing processing can be determined according to the communication frequency between the communication data processing module and the power module. Generally, if the frequency at which the communication data processing module completes one round of communication with all the power modules is 10 Hz, the maximum calculation frequency of the output voltage compensation value is 1 Hz. Among them, the calculation frequency of the output voltage compensation value is equivalent to the calculation frequency for performing current sharing processing on each power module, and the communication frequency is greater than the calculation frequency.

[0079] Step 104: Determine the current sharing period according to the calculated frequency.

[0080] The purpose of this step is to determine the current sharing period according to the calculated frequency determined above. Still taking the previous example for illustration, when the calculated frequency is 1 Hz, according to the conversion formula between frequency and time, the corresponding current sharing period can be determined to be 1 s.

[0081] It should be noted that the above communication frequency and calculated frequency are exemplary. The communication frequency is mainly related to the number of power modules, communication protocol, and communication speed. For example: the more the number of power modules, under the condition of constant communication speed, the longer the time for the communication data processing module to traverse all power modules to read the load current value, the smaller the communication frequency, and the smaller the calculation frequency of the output voltage compensation value.

[0082] In other words, in this embodiment, the communication frequency is determined by the number of power modules, communication protocol, and communication baud rate. The calculated frequency is adjusted according to the communication frequency, and according to the requirements of current sharing accuracy in actual engineering, on the basis of satisfying the above variation relationship, the communication frequency is generally greater than or equal to 10 times the calculated frequency. For example, the communication frequency is 10 Hz and the calculated frequency is 1 Hz.

[0083] It should be noted that if the calculated frequency is too large and causes oscillation, the size of the calculated frequency can also be adjusted to make it smaller; and the proportional relationship between the above communication frequency and calculated frequency is exemplary, and it can be set correspondingly according to different requirements of current sharing accuracy in actual engineering and combined with engineering experience.

[0084] In some alternative ways of this embodiment, after determining the communication frequency of the communication data processing module, different output current filtering parameters can also be set according to the communication frequency, such as the filtering frequency threshold of the low-pass filter, and the filtering frequency threshold is used to indicate the maximum frequency that can pass through the low-pass filter. Among them, the low-pass filter can be a digital low-pass filter or an analog low-pass filter. The filtering frequency threshold of the low-pass filter for output voltage sampling is relatively high, about dozens to hundreds of kHz; the filtering frequency threshold of the low-pass filter for output current sampling is positively correlated with the communication frequency, that is, the greater the communication frequency, the greater the filtering frequency threshold of the low-pass filter for output current; the smaller the communication frequency, the smaller the filtering frequency threshold of the low-pass filter for output current.

[0085] It should be understood that when the communication frequency is higher, it indicates that the time required for the communication data processing module to obtain the load current values of the first power supply module to the last power supply module and output the average value is shorter. During this period, there will not be much interference change in the load current values of the power supply modules, so the filtering frequency threshold of the low-pass filter for outputting current can be increased; when the communication frequency is lower, it indicates that the time required for the communication data processing module to obtain the load current values of the first power supply module to the last power supply module and output the average value is longer. During this period, there will be relatively large interference changes in the load current values of the power supply modules. In order to filter out more unnecessary interference currents, the filtering frequency threshold of the low-pass filter for outputting current needs to be decreased.

[0086] In one example, the filtering frequency threshold of the low-pass filter for outputting current should satisfy being less than 3 / (2*π*Td), where Td is the time required for the communication data processing module to obtain the load current values of the first power supply module to the last power supply module and output the average value.

[0087] In another example, in the case where the calculation frequency has been determined to be 1 Hz as described above, the filtering frequency threshold of the low-pass filter can also be set to 3 times the calculation frequency, that is, 3 Hz.

[0088] In addition, in this embodiment, the filtering frequency threshold is set to be greater than the calculation frequency and less than the communication frequency.

[0089] In this embodiment, by increasing the interaction between the communication data processing module and each power supply module, on the basis of not adding extra lines, the calculation frequency of the output voltage compensation value and the filtering frequency threshold of the low-pass filter are determined according to the communication frequency, which is beneficial to improving the sampling accuracy of the output current of each power supply module.

[0090] Thus, after determining the filtering frequency threshold of the low-pass filter, further referring to Figure 6 , the determination of the load current value of each power supply module described in the foregoing example includes:

[0091] Step 1011A: The output voltage and current sampling circuit samples the output current values of each of the power supply modules to obtain a plurality of sampled current values.

[0092] In this embodiment, the description of step 1011A can refer to the foregoing example, and the present application will not elaborate herein.

[0093] Step 1012A: The low-pass filter performs filtering processing on the plurality of sampled current values to calculate the load current value of each power supply module.

[0094] In this embodiment, taking the power supply module x as an example, the low-pass filter can perform filtering processing on multiple continuously collected sampled current values according to the previously determined filtering frequency threshold.

[0095] In yet another specific embodiment, the power supply system does not include the communication data processing module as described above. At this time, as Figure 7 shown, determining the load current values of each power supply module and calculating the average value of the load current values includes:

[0096] Step 1011B: Each of the power supply modules samples its own current value to generate its own first load current value;

[0097] Step 1012B: Each of the power supply modules receives the second load current values of each of the power supply modules sent by at least one of the power supply modules through broadcasting, obtains a plurality of second load current values, and generates the average value of the first load current value and the plurality of second load current values according to the plurality of second load current values and the first load current value.

[0098] It should be noted that when the power supply system does not include the communication data processing module as described above, multi-master communication is performed between the power supply modules through the CAN communication protocol.

[0099] Step 102: For each of the power supply modules, when it is determined that the absolute value of the difference between the average value and the load current value of each of the power supply modules is greater than the absolute value of a preset current bias threshold, calculate the output voltage compensation value of the power supply module corresponding to the load current value, where the output voltage compensation value is used to instruct the power supply module corresponding to the load current value to adjust the output voltage.

[0100] According to the foregoing, so far, it has been possible to determine the load current values of each power supply module in the current current sharing period and the average value of all load current values. Further, compare the load current values of each power supply module with the average value. If it is determined that the absolute value of the difference between the load current value of each power supply module and the average value is greater than the preset current bias threshold, then calculate the output voltage compensation value of the power supply module corresponding to the load current value, where the output voltage compensation value is used to instruct the power supply module corresponding to the load current value to adjust the output voltage.

[0101] That is to say, when the absolute value of the difference between the load current value and the average value is greater than the absolute value of the preset current bias threshold, it indicates that the current sharing deviation of this power supply module is relatively large. Therefore, it is necessary to calculate the output voltage compensation value of the power supply module corresponding to the load current value and adjust the output voltage of the power supply module corresponding to the load current value according to the indication of the output voltage compensation value, so as to effectively improve the current sharing accuracy between the power supply modules.

[0102] It should be understood that the current bias threshold is the maximum deviation allowed between the load current value and the average value. When the absolute value of the difference between the load current value and the average value is less than the absolute value of the preset current bias threshold, it indicates that the load current value of the power supply module is within the allowed deviation range. At this time, there is no need to adjust the output voltage of the power supply module, and there is no need to calculate the output voltage compensation value of the power supply module corresponding to the load current value.

[0103] It should be noted that when the absolute value of the difference between the load current value and the average value is equal to the absolute value of the preset current bias threshold, it can be set according to the actual situation whether to adjust the output voltage of the power supply module or not. Among them, if there is no need to adjust the output voltage of the power supply module, there is no need to calculate the output voltage compensation value of the power supply module corresponding to the load current value; if it is necessary to adjust the output voltage of the power supply module, then according to the voltage adjustment method when the absolute value of the difference between the load current value and the average value involved in the embodiment of the present application is greater than the absolute value of the preset current bias threshold, calculate the output voltage compensation value of the power supply module corresponding to the load current value, and then adjust the output voltage of the power supply module corresponding to the load current value.

[0104] Furthermore, the absolute value of the difference between the load current value and the average value described above being greater than the absolute value of the preset current bias threshold can be expressed by the following formula:

[0105] |Iout_avg - Iout_Filterx| > |Ioffset|

[0106] Wherein, Iout_avg is the average value of the load current value, Iout_Filterx is the load current value of power supply module x, and Ioffset is the preset current bias threshold, which is related to the required current sharing accuracy. For example, the absolute value of the preset current bias threshold is 2% of the average value of the load current value; or 1% of the rated current at full load. The present application does not make a limitation in this regard. In this embodiment, the corresponding preset current bias threshold can be set according to the actual current sharing accuracy requirements.

[0107] Based on the adjustment of the output voltage of each power supply module in a current sharing cycle described above, one voltage adjustment cannot determine whether the difference between the load current value and the average value is adjusted within the deviation range. Therefore, it is also necessary to repeat the above method in the next current sharing cycle of the current current sharing cycle until within a current sharing cycle, it can be ensured that the absolute value of the difference between the load current value and the average value of all power supply modules is not greater than the absolute value of the preset current bias threshold, so as to achieve high-precision digital current sharing for the power supply system.

[0108] It should be understood that when there is a deviation between the load current value and the average value of the load current values, the load current value can be greater than the average value or less than the average value. Therefore, the preset current bias threshold is set to include a first current bias threshold Ioffset 1 and a second current bias threshold Ioffset 2, where the first current bias threshold is greater than 0 and the second current bias threshold is less than 0. Then, the foregoing example formula can be converted to:

[0109] Iout_avg - Iout_Filter x > Ioffset 1 and

[0110] Iout_avg - Iout_Filter x < Ioffset 2

[0111] It should be noted that the first current bias threshold and the second current bias threshold can be set to different values according to the required current sharing accuracy, and the present application does not limit this.

[0112] Furthermore, according to different calculation methods of the output voltage compensation value of the power supply module corresponding to the load current value, the above step 102 further includes the following three optional methods respectively.

[0113] In an optional method of this embodiment, as Figure 8 shown, the above step 102 further includes:

[0114] Step 1021A: When the communication data processing module determines that the difference between the average value and the load current value of each power supply module is greater than the first current bias threshold, the communication data processing module calculates the first output voltage compensation value of the power supply module corresponding to the load current value, where the first output voltage compensation value includes a first adjustment voltage, and the first output voltage compensation value is used to instruct the power supply module corresponding to the load current value to increase the output voltage according to the first adjustment voltage.

[0115] In this embodiment, the communication data processing module compares the load current values of each power supply module with the average value. When it is determined that Iout_avg - Iout_Filter x > Ioffset 1, it indicates that the output voltage is too small, resulting in too small a load current value, and the output voltage needs to be increased. The communication data processing module calculates the first output voltage compensation value of the power supply module corresponding to the load current value, and the first output voltage compensation value includes a first adjustment voltage.

[0116] At this time, the communication data processing module sends the first adjustment voltage to the power supply module so that the power supply module increases the output voltage according to the first adjustment voltage.

[0117] Step 1022A. When the communication data processing module determines that the difference between the average value and the load current value of each power supply module is less than the second current bias threshold, the communication data processing module calculates a second output voltage compensation value for the power supply module corresponding to the load current value. The second output voltage compensation value includes a second adjustment voltage, and is used to instruct the power supply module corresponding to the load current value to reduce the output voltage according to the second adjustment voltage.

[0118] In this embodiment, the communication data processing module compares the load current values of each power supply module with the average value. When it is determined that Iout_avg - Iout_Filter x < Ioffset 2, it indicates that the output voltage is too large, resulting in an excessive load current value, and the output voltage needs to be adjusted downward. The communication data processing module calculates a second output voltage compensation value for the power supply module corresponding to the load current value. The second output voltage compensation value includes a second adjustment voltage.

[0119] At this time, the communication data processing module sends the second adjustment voltage to the power supply module, so that the power supply module reduces the output voltage according to the second adjustment voltage.

[0120] It should be noted that in this embodiment, the minimum value of the output voltage compensation value is 0 to ensure the overall stability of the output voltage.

[0121] For further reference Figure 9 , the communication data processing module receives the load current values Iout_Filter 1, Iout_Filter 2... Iout_Filter n reported by each power supply module, calculates the average value Iout_avg of the load current values, and further combines the preset current bias threshold Ioffset to determine whether to increase or decrease the output voltage of power supply module x, so as to achieve high-precision current sharing for each power supply module in the power supply system.

[0122] In another optional manner of this embodiment, to further improve the digital current sharing efficiency and reduce the signal interaction between the communication data processing module and each power supply module, the communication data processing module can directly send the calculated average value of the load current to each power supply module, so that the controller of the power supply module itself can directly compare its own load current value with the average value, and then adjust its own output voltage. Specifically, as Figure 10 shown, the above step 102 further includes:

[0123] Step 1021B. The communication data processing module sends the average value to each power supply module.

[0124] Step 1022B. When it is determined in each of the power modules that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the controller of each power module calculates a third output voltage compensation value for the power module corresponding to the load current value, where the third output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage.

[0125] In this embodiment, the controller of the power module itself can directly compare its own load current value with the average value. When it is determined that Iout_avg - Iout_Filter x > Ioffset 1, it indicates that the output voltage is too small, resulting in too small a load current value, and the output voltage needs to be increased. The controller of each power module calculates a third output voltage compensation value for the power module corresponding to the load current value, and the controller can directly increase the output voltage of the power module according to the third output voltage compensation value.

[0126] Step 1023B. When it is determined in each of the power modules that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the controller of each power module calculates a fourth output voltage compensation value for the power module corresponding to the load current value, where the fourth output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage.

[0127] In this embodiment, the controller of the power module itself can directly compare its own load current value with the average value. When it is determined that Iout_avg - Iout_Filter x < Ioffset 2, it indicates that the output voltage is too large, resulting in too large a load current value, and the output voltage needs to be decreased. The controller of each power module calculates a fourth output voltage compensation value for the power module corresponding to the load current value, and the controller can directly decrease the output voltage of the power module according to the fourth output voltage compensation value.

[0128] Further referring to Figure 11 , based on the average value Iout_avg of the load current value sent by the communication data processing module, the load current value Iout_Filter x of the power module x itself, and the preset current bias threshold, the controller can determine whether to increase or decrease the output voltage of the power module x to achieve high-precision current sharing for each power module in the power system.

[0129] It should be noted that whenever the power supply module receives the average value Iout_avg of the load current value sent by the communication data processing module, the method described in steps 1021B to 1023B is executed once. If the power supply module does not receive the average value Iout_avg of the load current value sent by the communication data processing module, it is considered that the communication between the communication data processing module and the power supply module fails. Then, the power supply module does not calculate the output voltage compensation value during this current sharing cycle and does not adjust the output voltage. If the power supply module still does not receive the average value Iout_avg of the load current value sent by the communication data processing module in the next few current sharing cycles, the output voltage compensation value of the voltage module is gradually reduced to 0 to ensure the overall stability of the output voltage.

[0130] In some alternative embodiments of this embodiment, for multi-master communication, such as when the communication protocol is the CAN bus protocol, the current sharing method of the present application can also be implemented without a communication data processing module. Specifically, each power supply module can calculate the average value of its own first load current value and the second load current values sent by other power supply modules received. Then, each power supply module can adjust its own output voltage according to this average value, as Figure 12 shown, the above step 102 further includes:

[0131] Step 1021C: When it is determined in each power supply module that the difference between the average value and the load current value of each power supply module is greater than the first current bias threshold, the controller of each power supply module calculates the fifth output voltage compensation value of the power supply module corresponding to the load current value, where the fifth output voltage compensation value is used to indicate that the power supply module corresponding to the load current value increases the output voltage.

[0132] In this embodiment, the controller of the power supply module itself can directly compare its own load current value with the average value. When it is determined that Iout_avg - Iout_Filter x > Ioffset 1, it indicates that the output voltage is too small, resulting in too small a load current value, and the output voltage compensation value needs to be increased. The controller of each power supply module calculates the third output voltage compensation value of the power supply module corresponding to the load current value, and the controller can directly increase the output voltage of the power supply module according to this third output voltage compensation value.

[0133] Step 1022C. When the difference between the average value and the load current value of each power module is less than the second current bias threshold, the controller of each power module calculates a sixth output voltage compensation value for the power module corresponding to the load current value, where the sixth output voltage compensation value is used to instruct the power module corresponding to the load current value to reduce the output voltage.

[0134] In this embodiment, the controller of the power module itself can directly compare its own load current value with the average value. When it is determined that Iout_avg - Iout_Filter x < Ioffset 2, it indicates that the output voltage is too large, resulting in an excessive load current value. The output voltage needs to be adjusted downward. The controller of each power module calculates a fourth output voltage compensation value for the power module corresponding to the load current value, and the controller can directly reduce the output voltage of the power module according to the fourth output voltage compensation value.

[0135] It should be noted that in the absence of a communication data processing module, data is transmitted between power modules through the CAN bus. The time for a power module to receive the load current values sent by all power modules and make one adjustment to its own output voltage compensation value can be regarded as a current sharing cycle.

[0136] Based on the traditional droop current sharing, without adding extra lines, this application can adjust the output voltages of each power module in a digital communication manner, thereby stabilizing the output voltage and improving the current sharing accuracy among the power modules.

[0137] Based on the same inventive concept, an embodiment of this application also provides a digital current sharing device for a power system, which can be used to implement the method described in the above embodiment. Since the principle of the digital current sharing device for a power system to solve problems is similar to that of the digital current sharing method for a power system, the implementation of the digital current sharing device for a power system can refer to the implementation based on the digital current sharing method for a power system, and the repeated parts will not be described again. Hereinafter, the term "unit" or "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the system described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0138] As Figure 13 shown, the digital current sharing device for a power system is configured to perform the following iterative operations:

[0139] In the current current sharing cycle, determine the load current value of each power module, obtain a plurality of the load current values, and calculate the average value of the plurality of the load current values;

[0140] For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than a preset current bias threshold, calculate an output voltage compensation value for the power module corresponding to the load current value, where the output voltage compensation value is used to instruct the power module corresponding to the load current value to adjust the output voltage.

[0141] Based on the same inventive concept, an embodiment of the present application further provides a power supply system, as Figure 1 shown, including a communication line, a load module, a plurality of power modules connected in parallel and adopting droop current sharing, and the digital current sharing device of the foregoing embodiment, which can be used to implement the method described in the foregoing embodiment. Since the power supply system includes the digital current sharing device of the foregoing embodiment, and the principle of solving problems by the digital current sharing device is similar to the digital current sharing method for the power supply system, the implementation of the power supply system of the present application can refer to the implementation of the digital current sharing method for the power supply system described above, and the repeated parts will not be described again.

[0142] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a device, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0143] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0144] It should also be noted that in the description of this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0145] Obviously, the above embodiments of this application are merely examples given to clearly illustrate this application, and are not intended to limit the implementation manners of this application. For those of ordinary skill in the art, based on the above description, other different forms of changes or variations can be made. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of this application still fall within the protection scope of this application. In summary, the content of this specification should not be construed as a limitation of this application.

Claims

1. A digital current sharing method for a power supply system, wherein, the power supply system includes a plurality of power modules connected in parallel and adopting droop current sharing. The digital current sharing method for the power supply system is characterized in that the method includes the following iterative operations: In the current current sharing period, determine the load current value of each power module, obtain a plurality of the load current values, and calculate the average value of the plurality of the load current values; For each power module, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculate the output voltage compensation value of the power module corresponding to the load current value, wherein the output voltage compensation value is used to instruct the power module corresponding to the load current value to adjust the output voltage.

2. The method according to claim 1, characterized in that, the power supply system further includes a communication data processing module, and the digital current sharing method for the power supply system further includes: Determine the calculation frequency for performing current sharing processing on each power module according to the communication frequency, wherein the communication frequency is used to indicate the frequency at which the communication data processing module completes one round of communication with all the power modules; Determine the current sharing period according to the calculation frequency, wherein the communication frequency is greater than the calculation frequency.

3. The method according to claim 2, characterized in that, the power module includes an output voltage and current sampling circuit and a low-pass filter; The determining the load current value of each power module includes: The output voltage and current sampling circuit samples the output current value of each power module to obtain a plurality of sampled current values; The low-pass filter performs filtering processing on the plurality of sampled current values and calculates the load current value of each power module.

4. The method according to claim 3, characterized in that, The low-pass filter performing filtering processing on the plurality of sampled current values includes: Determine the filtering frequency threshold for the low-pass filter to perform filtering processing on the plurality of sampled current values according to the communication frequency and the calculation frequency; wherein the filtering frequency threshold is positively correlated with the communication frequency; the filtering frequency threshold is greater than the calculation frequency and the filtering frequency threshold is less than the communication frequency, and the filtering frequency threshold is used to indicate the maximum frequency that can pass through the low-pass filter.

5. The method according to claim 4, characterized in that, The calculating the average value of the plurality of the load current values includes: Each power module sends its own load current value to the communication data processing module; The communication data processing module generates the average value of the load current values of all the power modules according to the load current value of each power module.

6. The method according to claim 5, characterized in that, the preset current bias threshold includes a first current bias threshold and a second current bias threshold; For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculating an output voltage compensation value for the power module corresponding to the load current value, includes: When the communication data processing module determines that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the communication data processing module calculates a first output voltage compensation value for the power module corresponding to the load current value, where the first output voltage compensation value includes a first adjustment voltage, and the first output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage according to the first adjustment voltage; When the communication data processing module determines that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the communication data processing module calculates a second output voltage compensation value for the power module corresponding to the load current value, where the second output voltage compensation value includes a second adjustment voltage, and the second output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage according to the second adjustment voltage; Wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

7. The method according to claim 5, characterized in that, the preset current bias threshold includes a first current bias threshold and a second current bias threshold; each of the power modules further includes a controller; For each of the power modules, when it is determined that the absolute value of the difference between the average value and the load current value of each power module is greater than the absolute value of a preset current bias threshold, calculating an output voltage compensation value for the power module corresponding to the load current value, includes: The communication data processing module sends the average value to each of the power modules; When each power module determines that the difference between the average value and the load current value of each power module is greater than the first current bias threshold, the controller of each power module calculates a third output voltage compensation value for the power module corresponding to the load current value, where the third output voltage compensation value is used to instruct the power module corresponding to the load current value to increase the output voltage; When each power module determines that the difference between the average value and the load current value of each power module is less than the second current bias threshold, the controller of each power module calculates a fourth output voltage compensation value for the power module corresponding to the load current value, where the fourth output voltage compensation value is used to instruct the power module corresponding to the load current value to decrease the output voltage; Wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

8. The method according to claim 7, characterized in that, data is transmitted between each of the power modules and the communication data processing module through an I2C bus, an SPI bus or an RS485 bus.

9. The method according to claim 1, wherein, the determining the load current value of each of the power supply modules to obtain a plurality of the load current values and calculating the average value of the plurality of the load current values includes: each of the power supply modules samples its own current value to generate its own first load current value; each of the power supply modules receives the second load current value of each of at least one of the power supply modules sent by broadcast, obtains a plurality of second load current values, and generates an average value of the first load current value and the plurality of second load current values according to the plurality of second load current values and the first load current value.

10. The method according to claim 9, wherein, the preset current bias threshold includes a first current bias threshold and a second current bias threshold; each of the power supply modules further includes a controller; for each of the power supply modules, in the case where it is determined that the absolute value of the difference between the average value and the load current value of each of the power supply modules is greater than the absolute value of the preset current bias threshold, calculating an output voltage compensation value of the power supply module corresponding to the load current value, including: in the case where each of the power supply modules determines that the difference between the average value and the load current value of each of the power supply modules is greater than the first current bias threshold, the controller of each of the power supply modules calculates a fifth output voltage compensation value of the power supply module corresponding to the load current value, wherein the fifth output voltage compensation value is used to instruct the power supply module corresponding to the load current value to increase the output voltage; in the case where each of the power supply modules determines that the difference between the average value and the load current value of each of the power supply modules is less than the second current bias threshold, the controller of each of the power supply modules calculates a sixth output voltage compensation value of the power supply module corresponding to the load current value, wherein the sixth output voltage compensation value is used to instruct the power supply module corresponding to the load current value to decrease the output voltage; wherein, the first current bias threshold is greater than 0, and the second current bias threshold is less than 0.

11. The method according to claim 10, wherein, data is transmitted between each of the power supply modules through a CAN bus.

12. A digital current sharing device for a power supply system, wherein, the power supply system includes a plurality of power supply modules connected in parallel and adopting droop current sharing, and is characterized in that the digital current sharing device for the power supply system is configured to perform the following iterative operations: in the current current sharing period, determine the load current value of each of the power supply modules to obtain a plurality of the load current values and calculate the average value of the plurality of the load current values; for each of the power supply modules, in the case where it is determined that the absolute value of the difference between the average value and the load current value of each of the power supply modules is greater than the absolute value of the preset current bias threshold, calculate an output voltage compensation value of the power supply module corresponding to the load current value, wherein the output voltage compensation value is used to instruct the power supply module corresponding to the load current value to adjust the output voltage.

13. A power supply system, wherein, It includes a communication line, a load module, and the digital current sharing device described in claim 12.

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