Differential battery equalization discharge control algorithm

Abstract

The invention relates to the technical field of power supply and battery control, in particular to a differential battery balanced discharge control algorithm, which comprises the following steps of: in the discharge process of a battery sharing manager, comparing an output voltage set value of each group of bidirectional DC / DC (Direct Current / Direct Current) module with an actually measured load voltage value, and obtaining a control voltage Vk by adopting PID (Proportion Integration Differentiation) operation; amplifying the output current value of the bidirectional DC / DC module n (n = 1, 2, 3, 4), comparing the output current value with the output control voltage Vk value, performing PID operation again, and outputting the control voltage Vk; and after the control voltage Vk is subjected to PWM signal generation, amplification and isolation, a PWM control signal is generated to drive a power switch tube corresponding to each module. According to the invention, a control algorithm for stably, accurately and automatically discharging according to the actual discharge capacity proportion of the batteries when multiple groups of differential batteries are connected in parallel can be realized, so that the stability and reliability of the whole power supply system are improved, the service life of the batteries is prolonged, and the utilization efficiency of battery resources is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply and battery control, and in particular to a differentiated battery balanced discharge control algorithm. Background Art

[0002] In many power supply scenarios such as communication base stations today, multiple groups of batteries with different characteristics are often used in parallel, such as lead-acid batteries of different periods, capacities, manufacturers, and age, or lithium batteries and lead-acid batteries mixed in parallel, or lithium batteries of different capacities in parallel, etc. The purpose is to integrate battery resources to ensure a stable and sufficient power supply.

[0003] However, it is not easy to realize the common discharge of multiple groups of differentiated batteries in parallel. The traditional battery sharing manager adopts the method of adding a control switch tube in each group of battery discharge circuit channels to make each channel work in a pulse mode, that is, in each working cycle, each channel is turned on in turn, and only one battery discharge switch is turned on each time, so that the discharge time of each group of batteries is allocated according to its capacity ratio, so as to make the average discharge current proportional to the capacity. However, this approach has obvious disadvantages. On the one hand, since each group of batteries is in a pulse working mode, it will cause the load power supply voltage ripple to be large, which is extremely unfavorable for base station loads that require stable operation; on the other hand, only one battery is discharged at each moment. In order to meet the load power supply requirements, the instantaneous pulse discharge current is extremely large, and such an instantaneous high current discharge is not conducive to the stability and long-term operation of the battery itself.

[0004] To overcome the above problems, it was subsequently proposed to design each channel of the battery sharing manager as a bidirectional DC / DC conversion mode, so that multiple differentiated batteries can be charged and discharged together to power the base station load. For example, in the "Technical Requirements and Testing Specifications for Base Station Battery Sharing Manager", it is proposed that in the common discharge mode, the system adjusts the discharge current of each branch according to the rated discharge capacity of each branch (battery rated capacity × discharge capacity coefficient) in the initial stage, so that each branch battery is discharged in proportion to the rated discharge capacity (error ≤ 10%), and after the battery sharing manager regularly completes the battery verification, it can automatically discharge according to the actual discharge capacity of the battery (actual discharge capacity C10 × discharge capacity coefficient) (error ≤ 10%). This requires that when multiple sets of bidirectional DC / DCs are running in parallel, the output voltage must be kept consistent, and the output current must be distributed at any ratio at any time, which places very high demands on the control of multiple sets of bidirectional DC / DC converters (power supplies). Because when general power modules are connected in parallel, the output voltage can be consistent, but the output current is determined by the equivalent internal resistance of each module, which is difficult to maintain consistency. Even if current sharing measures are adopted, the output current of each module can only be approximately equal, but it is difficult to distribute the output current of each module in any proportion. Because of this, the battery sharing managers on the current market still find it difficult to truly automatically discharge accurately according to the actual discharge capacity ratio of the battery when facing the parallel discharge of different groups of batteries.

[0005] In view of the many shortcomings and limitations of the prior art in realizing the differentiated battery parallel discharge process, a more effective control algorithm is urgently needed to ensure that multiple groups of differentiated batteries can be stably, reasonably and automatically discharged in proportion according to the actual situation of the batteries when connected in parallel, thereby improving the stability and reliability of the entire power supply system and the performance of the batteries. The differentiated battery balanced discharge control algorithm of the present invention comes into being. Summary of the invention

[0006] The purpose of the present invention is to provide a differentiated battery balanced discharge control algorithm, which can realize a control algorithm that stably and accurately discharges multiple groups of differentiated batteries according to the actual discharge capacity ratio of the batteries when they are connected in parallel, thereby improving the stability and reliability of the entire power supply system, extending the service life of the battery, and optimizing the utilization efficiency of battery resources.

[0007] To achieve the above object, the present invention provides a differentiated battery balanced discharge control algorithm. Taking a four-channel battery sharing manager with four bidirectional DC / DC converters as an example, the specific steps are as follows: S1. When the battery sharing manager is discharging, the output voltage setting value (i.e., the load voltage given value) of each group of bidirectional DC / DC modules is compared with the actually measured load voltage value, and the PID operation is applied to the comparison voltage to output the control voltage Vk; S2, the output current value of the bidirectional DC / DC module n (n=1, 2, 3, 4) is amplified by the module current amplification factor, and then compared with the output control voltage Vk value, and the PID operation is performed on the comparison voltage again to output the control voltage Vk; S3. After the control voltage Vk is generated, amplified and isolated by the PWM signal, a PWM control signal is generated to drive the power switch tube corresponding to each module.

[0008] Among them, the module current amplification factor is dynamically adjusted according to the capacity changes of each different battery group. In the initial stage, it is allocated according to the rated discharge capacity ratio of each branch battery. After the battery sharing manager regularly completes the capacity verification of all batteries, it is automatically allocated according to the actual discharge capacity ratio of the battery.

[0009] Furthermore, when the capacity ratio of the four groups of different batteries is C1:C2:C3:C4 (C1+C2+C3+C4=1), in order to make the discharge current ratio of the four groups of batteries be C1:C2:C3:C4, the module current amplification factors in the four groups of DC / DC converter module control circuits are set to be 1 / C1, 1 / C2, 1 / C3, 1 / C4 respectively, and the battery sharing manager control system sets the value of the current amplification factor of each module in real time according to the capacity ratio of the four groups of batteries.

[0010] Furthermore, the control algorithm of the present invention can be implemented by pure software programming or by hardware circuit construction.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. The present invention has precise discharge current proportional control: through unique voltage and current comparison and PID calculation and dynamically adjusted module current amplification factor, each branch battery can be accurately discharged according to the rated discharge capacity or the actual discharge capacity ratio, and the error is controlled within a very small range (≤5%), which effectively avoids the over-discharge or under-discharge of the battery and improves the balance and safety of battery use.

[0013] 2. The present invention has a stable power supply voltage: Compared with the traditional pulse control method, the algorithm of the present invention avoids the problem of large load power supply voltage ripple caused by pulse operation, provides a stable and reliable power supply voltage for base station loads, etc., ensures the stable operation of load equipment, and reduces the risk of equipment failure caused by voltage fluctuations.

[0014] 3. The present invention can protect the battery life: since it eliminates the instantaneous large current discharge, reduces the stress of the battery during the discharge process, and reduces the damage to components such as battery plates, it significantly extends the battery life and reduces the battery replacement cost and maintenance cost. It has important economic significance for scenarios such as large-scale use of battery-powered base stations.

[0015] 4. The present invention has wide applicability: The algorithm of the present invention is applicable to parallel combinations of various types of batteries, including parallel connection of lead-acid batteries of different periods, different capacities, different manufacturers, and different degrees of old and new, mixed parallel connection of lithium batteries and lead-acid batteries, and parallel connection of lithium batteries of different capacities, etc. It has strong versatility and compatibility, can meet the complex and changeable parallel power supply needs of batteries, and provides strong technical support for the integration and efficient utilization of battery resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the differentiated battery balanced discharge control algorithm of the present invention.

[0017] Figure 2 It is a working principle diagram of the base station battery sharing manager and its power supply system of the present invention.

[0018] Figure 3 It is a circuit principle diagram of the hardware circuit of the present invention to realize the module current amplification multiple. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1:

[0021] The present invention provides a differentiated battery balanced discharge control algorithm. First, in terms of hardware construction, such as Figure 2 As shown in the figure, a hardware system including a four-channel battery sharing manager and four bidirectional DC / DC converters is constructed. Each bidirectional DC / DC converter is connected to a group of differentiated batteries to ensure the stability and correctness of the circuit connection, and to ensure good electrical isolation performance between channels to prevent mutual interference.

[0022] like Figure 1As shown, in the system initialization stage, the initial module current magnification factor is calculated and set according to the rated parameters of each branch battery, including the rated capacity and other information. For example, when the rated capacity ratio of the four groups of batteries is known to be C1:C2:C3:C4, the "module current magnification factor" in the four-way DC / DC converter module control circuit is set to 1 / C1, 1 / C2, 1 / C3, and 1 / C4 respectively.

[0023] When the battery sharing manager enters the discharge working state: the actual voltage value at both ends of the load is collected in real time using a high-precision voltage sensor and transmitted to the controller. At the same time, the controller generates the output voltage setting value (load voltage given value) of each group of bidirectional DC / DC modules according to the preset load voltage requirements. The difference between the output voltage setting value and the actual measured load voltage value is calculated, and then the difference is input into the PID controller for PID operation. The PID controller dynamically adjusts the voltage error according to the preset proportional coefficient, integral time constant and differential time constant, and outputs the control voltage Vk.

[0024] For each bidirectional DC / DC module n (n=1, 2, 3, 4), the output current value is collected by the current sensor. After the output current value is amplified by the corresponding module current magnification factor, it is compared with the control voltage Vk value obtained above, and the difference is calculated again and input into another PID controller for PID operation to further optimize the control voltage Vk. In this process, the control system of the battery sharing manager monitors and adjusts the value of the current magnification factor of each module in real time according to the working status of the battery. If it is in the initial stage, the calculation is performed according to the pre-set module current magnification factor based on the rated discharge capacity ratio; if all battery capacity has been completed, the module current magnification factor is dynamically updated according to the actual discharge capacity ratio of the battery.

[0025] Finally, the control voltage Vk obtained after two PID operations is input into the PWM signal generation circuit, which generates a PWM signal with a corresponding duty cycle according to the size of the control voltage Vk. Then, after being processed by the signal amplification and isolation circuit, a PWM control signal capable of driving the power switch tube corresponding to each module is obtained, thereby controlling the output voltage and current of the bidirectional DC / DC converter and realizing the discharge of each branch battery according to a predetermined ratio.

[0026] In terms of software implementation, we develop specialized control software, which mainly includes the following functional modules: Data acquisition module: responsible for communicating with the voltage sensor and current sensor in the hardware system, collecting data such as load voltage value, output current value of each bidirectional DC / DC module in real time, and storing it in a pre-defined data buffer for subsequent calculation.

[0027] Voltage control module: realizes the comparison between the output voltage set value and the actual measured value and the PID operation function, calculates the control voltage Vk according to the input voltage difference, and outputs it to the current control module.

[0028] Current control module: completes the adjustment of the amplification factor of the output current value of the bidirectional DC / DC module, the comparison with the control voltage Vk, and the second PID operation to obtain the final control voltage Vk and pass it to the PWM signal generation module.

[0029] PWM signal generation module: Based on the received control voltage Vk, it generates the duty cycle information of the PWM signal according to a specific algorithm, and then transmits it to the signal amplification and isolation module.

[0030] Module current amplification factor adjustment module: Calculates and updates the current amplification factor of each bidirectional DC / DC module according to the working stage of the battery (initial stage or post-capacity stage) and battery capacity information, and provides accurate amplification factor parameters for the current control module.

[0031] Through the specific implementation method combining the above hardware and software, the differentiated battery balanced discharge control algorithm of the present invention can be effectively applied in the parallel discharge scenario of multiple groups of differentiated batteries, realize stable and accurate battery balanced discharge control, and improve the performance and reliability of the entire power supply system.

[0032] Embodiment 2:

[0033] Similar to the first embodiment, this embodiment introduces a method of using a hardware circuit to implement a function of increasing the current amplification factor of a module.

[0034] like Figure 3 As shown, the circuit consists of an operational amplifier A1, fixed resistors R2, R3, R4 and a programmable resistor R1.

[0035] R1 is a programmable resistor that can be controlled by the microcontroller ( Figure 1 The resistance value is selected by the control system of the battery sharing manager in the middle.

[0036] Furthermore, for example, the resistance of R1 can be selected through switch combinations to include options such as 0kΩ, 1kΩ, 2kΩ, 3kΩ, 4kΩ, 5kΩ, 6kΩ, 7kΩ, 8kΩ, 9kΩ, 10kΩ, 11kΩ, 12kΩ, 13kΩ, 14kΩ, and 15kΩ.

[0037] The microcontroller controls the switch combination inside R1 so that the resistance value of R1 is any one of the above resistance values.

[0038] The resistance value of R2 is fixed, select 1kΩ; the resistance value of R3 is fixed, select 1kΩ; the resistance value of R2 is fixed, select 15kΩ.

[0039] The amplification factor of the operational amplifier can be calculated as 16k / (R1+1k). If the rated capacity ratio of the battery group is 0.6, the microcontroller can control the switch combination inside R1 to make its resistance 9kΩ.

[0040] The subsequent calculation and control process are similar to those in the first embodiment and will not be described again here.

[0041] The above shows and describes 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 by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A differentiated battery balanced discharge control algorithm, characterized in that: The following steps are involved: S1. During the discharge process of the battery sharing manager, the output voltage setting value of each group of bidirectional DC / DC modules is compared with the actual measured load voltage value, and the control voltage Vk is obtained by PID operation; S2, amplify the output current value of the bidirectional DC / DC module n (n=1, 2, 3, 4), compare it with the output control voltage Vk value, perform PID operation again, and output the control voltage Vk; S3. After the control voltage Vk is generated, amplified and isolated by the PWM signal, a PWM control signal is generated to drive the power switch tube corresponding to each module.

2. The differentiated battery balanced discharge control algorithm according to claim 1, characterized in that: The specific operation steps of step S1 are: S11, using the data acquisition module to collect the actual voltage value at both ends of the load in real time, and transmit it to the controller; S12, the controller generates an output voltage setting value for each group of bidirectional DC / DC modules according to a preset load voltage requirement; S13, calculating the difference between the output voltage setting value and the actually measured load voltage value; S14, the difference is input into the PID controller and combined with the voltage control module to perform PID operation, the PID controller dynamically adjusts the voltage error according to the preset proportional coefficient, integral time constant and differential time constant, and outputs the control voltage Vk to the current control module.

3. The differentiated battery balanced discharge control algorithm according to claim 2, characterized in that: The specific operation steps of step S2 are: S21. For each bidirectional DC / DC module n (n=1, 2, 3, 4), collect its output current value through a current sensor; S22, after the output current value is amplified by the current control module and the module current amplification factor adjustment module, the output current value is compared with the control voltage Vk value obtained in step S14; S23, calculate the difference again and input it into another PID controller for PID operation to further optimize the control voltage Vk.

4. The differentiated battery balanced discharge control algorithm according to claim 1, characterized in that: The multiple by which the output current value is amplified in step S2 is dynamically adjusted according to the capacity change of each difference battery group. In the initial stage, it is allocated according to the rated discharge capacity ratio of each branch battery. After all battery capacity verification is completed, it is adjusted according to the actual discharge capacity ratio of the battery.

5. The differentiated battery balanced discharge control algorithm according to claim 3, characterized in that: The specific operation steps of step S3 are: S31, inputting the control voltage Vk obtained through two PID operations into a PWM signal generation module, which generates a PWM signal with a corresponding duty cycle according to the magnitude of the control voltage Vk; S32. After the signal is amplified and processed by the isolation circuit, a PWM control signal capable of driving the power switch tube corresponding to each module is obtained, thereby controlling the output voltage and current of the bidirectional DC / DC converter, and realizing the discharge of each branch battery according to a predetermined ratio.

6. The differentiated battery balanced discharge control algorithm according to claim 2, characterized in that: The data acquisition module is responsible for communicating with the voltage sensor and current sensor in the hardware system, collecting data such as the load voltage value and the output current value of each bidirectional DC / DC module in real time, and storing it in a predefined data buffer for subsequent calculation.

7. The differentiated battery balanced discharge control algorithm according to claim 2, characterized in that: The voltage control module is used to compare the output voltage setting value with the actual measured value and implement the PID operation function, calculate the control voltage Vk according to the input voltage difference, and output it to the current control module.

8. The differentiated battery balanced discharge control algorithm according to claim 3, characterized in that: The current control module is used to complete the amplification adjustment of the output current value of the bidirectional DC / DC module, the comparison with the control voltage Vk and the second PID operation, obtain the final control voltage Vk, and pass it to the PWM signal generation module.

9. The differentiated battery balanced discharge control algorithm according to claim 3, characterized in that: The module current magnification adjustment module is used to calculate and update the current magnification of each bidirectional DC / DC module according to the working stage of the battery and the battery capacity information, and provide accurate magnification parameters for the current control module.

10. The differentiated battery balanced discharge control algorithm according to claim 5, characterized in that: The PWM signal generating module is used to generate duty cycle information of the PWM signal according to the received control voltage Vk in accordance with a specific algorithm, and then transmit it to the signal amplifying and isolating module.

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