Battery constant current and constant voltage control method and system based on analog digital loop

Abstract

The invention provides a battery constant-current and constant-voltage control system based on an analog digital loop. The battery constant-current and constant-voltage control system comprises a sampling circuit, a floating charge control system, a driving circuit and an analog loop. The sampling circuit collects an output signal of the driving circuit and feeds back a sampling signal to the floating charge control system; the floating charge control system outputs a voltage given signal and a current given signal to the analog loop, and adjusts the voltage given signal and the current given signal according to the sampling signal; the simulation loop generates a loop control signal according to the voltage given signal and the current given signal; the driving circuit drives the power converter according to the loop control signal and based on the signal, so that the power converter outputs the charging voltage and the charging current corresponding to the current given value and the voltage given value. Therefore, the problem of large current ripples caused by the combined action of a double closed-loop control voltage loop and a double closed-loop control current loop is solved; meanwhile, a mode of combining software adjustment and a simulation loop is adopted, and the problem that a traditional software control mode is insufficient in dynamic state is solved.

Description

Technical Field

[0001] This invention relates to the field of battery charging technology, and more particularly to a battery constant current and constant voltage control method and system based on analog digital loop. Background Technology

[0002] Existing battery charging control algorithms use constant current and constant voltage dual closed-loop control, or switch to constant voltage control after identifying the float charging stage. In the constant current and constant voltage control algorithm, both loops operate simultaneously, making it difficult to simultaneously meet dynamic timing requirements, overshoot requirements, and current / voltage stability accuracy requirements. Algorithms that switch to single voltage loop control during the float charging stage are prone to voltage or current surges during the switch. Furthermore, under simple constant voltage control, current ripple and current stability cannot achieve the 0.01% or higher accuracy requirements required by battery testing equipment.

[0003] Therefore, a new solution is needed. Summary of the Invention

[0004] According to one aspect of the present invention, a constant current and constant voltage control system for battery charging and discharging is provided, comprising a sampling circuit, a float charging control system, a drive circuit, and an analog loop. The input terminal of the sampling circuit is connected to the output terminal of the drive circuit, the output terminal of the sampling circuit is connected to the input terminal of the float charging control system, the output terminal of the float charging control system is connected to the input terminal of the analog loop, and the output terminal of the analog loop is connected to the input terminal of the drive circuit. The sampling circuit is used to acquire the output signal of the drive circuit and feed the sampled signal back to the float charging control system. The float charging control system is used to output a voltage setpoint signal and a current setpoint signal to the analog loop, and adjust the voltage setpoint signal and the current setpoint signal according to the sampled signal. The analog loop is used to generate a loop control signal according to the voltage setpoint signal and the current setpoint signal. The drive circuit is used to drive a power converter according to the loop control signal, so that the power converter outputs a charging voltage and a charging current corresponding to the current setpoint value and the voltage setpoint value.

[0005] In the constant current and constant voltage control system for battery charging and discharging provided by the present invention, the sampling signal includes voltage sampling values ​​and current sampling values, and the float charging control system includes: The judgment unit is used to determine whether to enter the float charging stage based on the voltage sample value and the voltage given signal, and to generate a current adjustment signal after entering the float charging stage. A given signal output unit is configured to output the voltage given signal and the current given signal to the analog loop, and after receiving the current adjustment signal, adjust the current given signal to the current sample value.

[0006] In the constant current and constant voltage control system for battery charging and discharging provided by the present invention, the analog loop includes a voltage loop, an adder, and a current loop connected in sequence. The output terminal of the given signal output unit is connected to the input terminal of the voltage loop and the first input terminal of the adder, respectively. The output terminal of the voltage loop is connected to the second input terminal of the adder, the output terminal of the adder is connected to the input terminal of the current loop, and the output terminal of the current loop is connected to the input terminal of the drive circuit. The voltage loop receives the voltage given signal output by the given signal output unit, and the adder receives the output signal of the voltage loop and the current given signal output by the given signal output unit.

[0007] According to another aspect of the present invention, a constant current and constant voltage control method for battery charging and discharging is also provided, applied to the constant current and constant voltage control system for battery charging and discharging as described above, the control method comprising: The float charge control system outputs voltage and current command signals to the analog loop. The analog loop generates a loop control signal based on the voltage and current given signals. The driving circuit drives the power converter according to the loop control signal, so that the power converter outputs a charging voltage and a charging current corresponding to the current setpoint and the voltage setpoint; The sampling circuit acquires the output signal of the drive circuit and feeds the sampled signal back to the float charging control system. The float charge control system adjusts the voltage and current input signals based on the sampled signals.

[0008] In the constant current and constant voltage control method for battery charging and discharging provided by the present invention, the sampling signal includes a voltage sampling value and a current sampling value. The step of the float charging control system adjusting the voltage setpoint signal and the current setpoint signal according to the sampling signal includes: Based on the voltage sample value and the voltage setpoint signal, it is determined whether to enter the float charging stage. After entering the float charging stage, a current adjustment signal is generated. Based on the current adjustment signal, the current setpoint signal is adjusted to the current sample value; The voltage setpoint signal and the adjusted current setpoint signal are output to the analog loop.

[0009] According to another aspect of the present invention, a constant current and constant voltage control device for battery charging and discharging is also provided, comprising a processor and a memory, wherein the memory stores a computer program, and the computer program, when executed by the processor, implements the steps of the battery constant current and constant voltage control method based on analog-digital loop as described above.

[0010] According to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, characterized in that, when the computer program is executed by a processor, it implements the steps of the method described above.

[0011] The battery constant current and constant voltage control method and system based on analog-digital loop of the present invention has the following beneficial effects: In the present invention, the float charging control system performs logical judgment and calculation based on the real-time sampled voltage and current to obtain the current and voltage setpoints required at present, and uses them as the setpoints for the dual closed-loop analog control loop. After calculation, the analog loop outputs to the drive circuit so that the device outputs the set voltage and current. Thus, the problem of large current ripple caused by the combined action of the voltage and current loops of the dual closed-loop control is solved. At the same time, the present invention adopts a combination of software adjustment and analog loop to solve the problem of insufficient dynamics in traditional software control methods. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort: Figure 1 The diagram shown is a schematic of a battery constant current and constant voltage control system based on an analog-digital loop provided in an embodiment of the present invention. Figure 2 As shown Figure 1 The schematic diagram of the voltage loop is shown. Detailed Implementation

[0013] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Typical embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0015] Figure 1 The diagram shown is a schematic of a battery constant current and constant voltage control system based on an analog-digital loop, according to an embodiment of the present invention. Figure 1As shown, the constant current and constant voltage control system for battery charging and discharging provided by the present invention includes a sampling circuit 10, a float charging control system 20, a drive circuit 30, and an analog loop 40. The output terminal of the sampling circuit is connected to the input terminal of the float charging control system, the output terminal of the float charging control system is connected to the input terminal of the analog loop, and the output terminal of the analog loop is connected to the input terminal of the drive circuit. The float charging control system outputs a voltage and current setpoint signal to the analog loop and adjusts the voltage and current setpoint signals according to the sampling signal. The analog loop generates a loop control signal based on the voltage and current setpoint signals. The drive circuit drives a power converter based on the loop control signal, causing the power converter to output a charging voltage and charging current corresponding to the current and voltage setpoint values. In this embodiment, the float charging control system performs logical judgments and calculations based on real-time sampled voltage and current to obtain the required current and voltage setpoints, which are then used as the setpoints for the dual-closed-loop analog control loop. After calculation, the analog loop outputs to the drive circuit, causing the device to output the set voltage and current. This solves the problem of large current ripple caused by the combined action of the voltage and current loops in the dual-closed-loop control. Simultaneously, this invention employs a combination of software adjustment and the analog loop, addressing the lack of dynamics in traditional software control methods.

[0016] Specifically, in one embodiment of the present invention, the sampling circuit 10 typically includes a voltage divider resistor network and a current sampling resistor (or Hall sensor) and a corresponding conditioning circuit, for real-time acquisition of the voltage V_out and current I_out at the output of the drive circuit, and converting them into voltage sampling values ​​V_sense and current sampling values ​​I_sense suitable for subsequent circuit processing, and feeding back the voltage sampling values ​​V_sense and current sampling values ​​I_sense to the float charging control system.

[0017] Specifically, in one embodiment of the present invention, the float charging control system 20 receives a voltage sample value V_sense and a current sample value I_sense, and internally includes a judgment unit and a given signal output unit. The judgment unit continuously monitors the voltage sample value V_sense and compares it with the system's preset battery full-charge voltage (i.e., the voltage setpoint V_ref_cccv in the constant voltage stage). When the voltage sample value V_sense reaches or exceeds a certain threshold (e.g., 99.8%) of the voltage setpoint V_ref_cccv and remains so for a period of time (e.g., 10 milliseconds), the judgment unit determines that the battery has entered a saturated state and should switch to float charging, and then sends a current adjustment signal to the given signal output unit. Under normal conditions, the given signal output unit outputs a constant voltage setpoint signal V_ref (equal to V_ref_cccv) and a preset constant current stage current setpoint I_ref_cc. Once the current adjustment signal is received, the given signal output unit immediately updates the currently output current setpoint I_ref to the currently received current sample value I_sense and keeps this value unchanged. Meanwhile, the voltage reference signal V_ref can remain unchanged or be switched to a slightly lower V_ref_float (float charging voltage) according to the float charging requirements. Therefore, in the float charging control system 20, the judgment unit is used to determine whether to enter the float charging stage based on the voltage sample value and the voltage reference signal. After entering the float charging stage, a current adjustment signal is generated. The reference signal output unit is used to output the voltage reference signal and the current reference signal to the analog loop, and after receiving the current adjustment signal, adjust the current reference signal to the current sample value.

[0018] Specifically, in one embodiment of the present invention, analog loop 40 receives a voltage setpoint V_ref and a current setpoint I_ref. Its voltage loop 41 (typically composed of an error amplifier and a compensation network) compares and integrates the voltage setpoint V_ref with V_sense, outputting a voltage error signal V_comp. This signal V_comp is fed into one input of adder 42. The other input of the adder directly receives the current setpoint I_ref from the float charge control system. The adder adds the current setpoint I_ref to the voltage error signal V_comp, and its output I_ref_combined serves as the setpoint signal for current loop 43. The current loop compares and adjusts I_ref_combined with I_sense, ultimately outputting a PWM duty cycle control signal or an analog voltage signal as the loop control signal. The drive circuit 30 then receives this loop control signal, performs level shifting and dead-time control, etc., to generate a gate signal for driving the power switch (such as a MOSFET), controlling the switching action of the power converter, thereby precisely regulating its output voltage and current.

[0019] Voltage loop principle as follows Figure 2 As shown, the differential signal between the voltage setpoint V_ref and the voltage feedback V_sense is proportional-integral (PI) by an operational amplifier and then limited. The minimum value after limiting is 0V. An inverter then inverts the limiting result, resulting in a voltage output less than or equal to 0. When operating in charging mode, the battery voltage is low, and V_sense is much smaller than V_ref, causing negative saturation in the voltage loop output. After limiting and inversion, the output V_comp is 0V. At this point, I_ref plays a dominant role, and the system control current remains constant at I_ref_cc. When the battery voltage rises to or exceeds V_ref, the voltage loop exits negative saturation and begins closed-loop operation. The difference between the voltage setpoint and the voltage feedback is now positive. Therefore, after PI, limiting, and inversion, the output V_comp value will be less than 0, and V_comp will gradually decrease, causing I_ref_combined to decrease accordingly. The current loop control output current I_out follows suit, simultaneously clamping the voltage V_out precisely at V_ref. When operating in discharge mode, the principle is the same as in charging mode. In this mode, the operational amplifier differential signal is V_ref - V_sense. Therefore, when the battery voltage is far from the target value at the start of discharge, V_comp is also 0V. Subsequent changes are consistent with charging.

[0020] When the judgment unit determines that the float charging condition is met, a current lockout operation is triggered. The given signal output unit locks I_ref to the current I_sense (a very small value I_float). Thereafter, the system will charge using I_float as the new constant current target, while the voltage remains V_ref (or V_ref_float). Since I_ref changes from I_ref_cc to I_float at the instant of switching, and I_float is exactly equal to the actual current before the switch, there is no jump in the given value for the current loop, achieving a completely smooth transition.

[0021] In this invention, during the non-float charging phase, the current control target is the current limit value. At this time, the voltage error is relatively large, and the voltage loop output is saturated. In reality, only the current error has an effect on adjusting the output duty cycle, and the control module is similar to constant current control. Since the control of the current loop is jointly determined by the voltage loop output and the current loop setpoint, when the battery voltage is charged or discharged to the target value, i.e., during the float charging phase, the current loop setpoint is modified in real time to be the filtered value of the current sampling. At this time, the current loop setpoint follows the current, and the current during the float charging phase is still mainly controlled by the current loop, with the voltage loop having a very small weight. This avoids large changes in the control quantity caused by simultaneous adjustment of the two loops. Therefore, this algorithm can ensure that the calculation error of the current in each cycle does not fluctuate significantly, and the output fluctuation corresponding to the current error is small, thereby achieving a current ripple requirement of 0.01% or even higher.

[0022] According to another aspect of the present invention, a constant current and constant voltage control method for battery charging and discharging is also provided, comprising the following steps: The float charge control system outputs voltage and current command signals to the analog loop. The analog loop generates a loop control signal based on the voltage and current given signals. The driving circuit drives the power converter according to the loop control signal, so that the power converter outputs a charging voltage and a charging current corresponding to the current setpoint and the voltage setpoint; The sampling circuit acquires the output signal of the drive circuit and feeds the sampled signal back to the float charging control system. The float charging control system adjusts the voltage and current command signals based on the sampled signals. The sampled signals include voltage and current sample values. Based on the voltage sample values ​​and the voltage command signal, it determines whether to enter the float charging stage. If the float charging stage is entered, a current adjustment signal is generated. Based on the current adjustment signal, the current command signal is adjusted to the current sample value. The voltage and current command signals are then output to the analog loop.

[0023] In the constant current and constant voltage control method for battery charging and discharging provided by this invention, during the non-float charging stage (the initial stage of constant current CC and constant voltage CV), when the battery voltage is low, there is a large voltage error between the system setpoint and the feedback. At this time, the output of the error amplifier in the voltage loop will quickly reach the upper limit of saturation, which means that the voltage loop outputs a constant maximum compensation signal. In this state, the entire system degenerates into a typical single current loop control system, where the current loop quickly and accurately forces the output current to track the given current limit value, achieving pure constant current control. When the system enters the float charging stage, the setpoint of the current loop is updated in real time to the filtered value of the current sampling. By changing the setpoint of the current loop from a fixed value to a value that dynamically tracks the actual output current, the setpoint of the current loop and the feedback value are theoretically kept in sync instantaneously, thereby reducing the theoretical target value of the current error to an extremely low level. Under this setting, the current loop still serves as the main loop that directly controls the output duty cycle. Since the battery voltage has stabilized near the target float charge voltage, the voltage loop's output voltage error signal is extremely small. It only fine-tunes the current setpoint to compensate for the system's static error and minor load variations. The voltage loop's role is reduced to a fine-tuning mechanism rather than the primary source of control commands. This avoids the conflicts and oscillations caused by both loops simultaneously generating adjustment commands in traditional dual-loop switching. Because the current setpoint "follows" the actual current, the calculated current error value for each control cycle is kept within a very small range. Correspondingly, the duty cycle adjustment resulting from the current error after loop regulation is also extremely small, thus significantly reducing the output current ripple. By optimizing the loop parameters, this invention can easily achieve output current ripple accuracy of less than 0.01% or even higher, meeting the stringent power quality requirements of high-end applications.

[0024] This invention also provides a battery constant current and constant voltage control device based on an analog-digital loop, which may include: Memory, used to store computer programs; When a processor executes a computer program stored in the aforementioned memory, it can perform the following steps: The float charging control system outputs voltage and current command signals to the analog loop; the analog loop generates a loop control signal based on the voltage and current command signals; the drive circuit drives the power converter based on the loop control signal, causing the power converter to output charging voltage and charging current corresponding to the current and voltage command values; the sampling circuit acquires the output signal of the drive circuit and feeds the sampled signal back to the float charging control system; the float charging control system adjusts the voltage and current command signals based on the sampled signal.

[0025] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0026] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0027] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0028] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0029] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some or all of the components according to the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0030] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A constant current and constant voltage control system for battery charging and discharging, characterized in that, The system includes a sampling circuit, a float charge control system, a drive circuit, and an analog loop. The input of the sampling circuit is connected to the output of the drive circuit, the output of the sampling circuit is connected to the input of the float charge control system, the output of the float charge control system is connected to the input of the analog loop, and the output of the analog loop is connected to the input of the drive circuit. The sampling circuit is used to acquire the output signal of the drive circuit and feed the sampled signal back to the float charge control system. The float charge control system is used to output a voltage setpoint signal and a current setpoint signal to the analog loop and adjust the voltage setpoint signal and the current setpoint signal according to the sampled signal. The analog loop is used to generate a loop control signal based on the voltage setpoint signal and the current setpoint signal. The driving circuit is used to drive the power converter according to the loop control signal, so that the power converter outputs a charging voltage and a charging current corresponding to the current setpoint and voltage setpoint.

2. The constant current and constant voltage control system for battery charging and discharging according to claim 1, characterized in that, The sampling signal includes voltage sampling values ​​and current sampling values, and the float charging control system includes: The judgment unit is used to determine whether to enter the float charging stage based on the voltage sample value and the voltage given signal, and to generate a current adjustment signal after entering the float charging stage. A given signal output unit is configured to output the voltage given signal and the current given signal to the analog loop, and after receiving the current adjustment signal, adjust the current given signal to the current sample value.

3. The constant current and constant voltage control system for battery charging and discharging according to claim 2, characterized in that, The analog loop includes a voltage loop, an adder, and a current loop connected in sequence. The output terminal of the given signal output unit is connected to the input terminal of the voltage loop and the first input terminal of the adder, respectively. The output terminal of the voltage loop is connected to the second input terminal of the adder, and the output terminal of the adder is connected to the input terminal of the current loop. The output terminal of the current loop is connected to the input terminal of the drive circuit. The voltage loop receives the voltage given signal output by the given signal output unit, and the adder receives the output signal of the voltage loop and the current given signal output by the given signal output unit.

4. A constant current and constant voltage control method for battery charging and discharging, characterized in that, The control method, applied to the constant current and constant voltage control system for battery charging and discharging as described in any one of claims 1-3, comprises: The float charge control system outputs voltage and current command signals to the analog loop. The analog loop generates a loop control signal based on the voltage and current given signals. The driving circuit drives the power converter according to the loop control signal, so that the power converter outputs a charging voltage and a charging current corresponding to the current setpoint and the voltage setpoint; The sampling circuit acquires the output signal of the drive circuit and feeds the sampled signal back to the float charging control system. The float charge control system adjusts the voltage and current input signals based on the sampled signals.

5. The constant current and constant voltage control method for battery charging and discharging according to claim 4, characterized in that, The sampling signal includes voltage sampling values ​​and current sampling values. The step of the float charging control system adjusting the voltage command signal and the current command signal according to the sampling signal includes: Based on the voltage sample value and the voltage setpoint signal, it is determined whether to enter the float charging stage. After entering the float charging stage, a current adjustment signal is generated. Based on the current adjustment signal, the current setpoint signal is adjusted to the current sample value; The voltage setpoint signal and the adjusted current setpoint signal are output to the analog loop.

6. A constant current and constant voltage control device for battery charging and discharging, characterized in that, It includes a processor and a memory, the memory storing a computer program that, when executed by the processor, implements the steps of the battery constant current and constant voltage control method based on an analog-digital loop as described in any one of claims 4 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in claim 4 or 5.

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