Buck converter sensorless control method and device under constant power load of energy storage system

Abstract

The application discloses a few-sensor control method and device of a Buck converter under a constant-power load of an energy storage system. The method comprises the following steps: a mathematical model of the Buck converter with the constant-power load is established, the power of the constant-power load to be controlled is expanded into a system state variable, and a subsystem to be estimated containing an inductor current and a load power is constructed; based on the immersion and invariance principle, the state to be estimated in the subsystem to be estimated is decomposed into the sum of an auxiliary dynamic term and an output-dependent term, so as to design a reduced-order state observer; wherein, the reduced-order state observer only collects the output capacitor voltage signal of the Buck converter, and can synchronously and on-line estimate the inductor current and the load power; according to the deterministic equivalence principle, an output voltage tracking controller is designed by using the backstepping method and based on the estimated values of the inductor current and the load power obtained by the reduced-order state observer, and a control duty ratio of the Buck converter is generated, so as to realize stable tracking control of the output voltage.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and in particular to a sensorless control method and device for a Buck converter under constant power load in an energy storage system. Background Technology

[0002] As a key component in DC distribution networks, microgrids, and new energy power generation, the performance of the internal converter devices in energy storage systems directly determines the power supply quality and stability of the system. Buck converters are widely used in the front-end DC voltage regulation of energy storage systems. Traditional control strategies typically require the installation of inductor current sensors to construct a dual closed-loop control system to achieve accurate voltage tracking and dynamic regulation. However, the introduction of additional current sensors not only increases the system hardware cost and device size but also makes them prone to aging or even failure during long-term operation or in complex environments, thus hindering the improvement of energy storage system reliability.

[0003] To overcome the limitations of hardware sensors, sensorless control technology has gradually become a research hotspot in recent years. For ordinary resistive loads or loads with known parameters, the Buck converter model is relatively simple, and the observer and controller designs are relatively mature. However, in actual energy storage scenarios, the downstream stage may be connected to constant power loads such as power conversion devices, motor drivers, and electronic loads. Constant power loads have negative impedance characteristics, and their load current and output voltage have a nonlinear relationship, which can easily weaken system damping and affect the stability of DC-side voltage. Secondly, the load power is often unknown and fluctuates dynamically in actual operation, resulting in unknown nonlinear coupling terms in the system model, making the design of traditional observers extremely difficult. Therefore, how to effectively estimate the inductor current and unknown load power under the condition of only acquiring the output voltage, and on this basis, complete stable and reliable voltage tracking control, is an urgent problem to be solved in sensorless control of Buck converters in energy storage systems. Summary of the Invention

[0004] This invention provides a sensorless control method and apparatus for a Buck converter under constant power load in an energy storage system, which solves the problems of high hardware cost, large device size and insufficient reliability caused by the reliance on inductor current sensors in traditional control strategies.

[0005] According to one aspect of the present invention, a sensorless control method for a Buck converter under constant power load in an energy storage system is provided, comprising:

[0006] A mathematical model of a Buck converter with a constant power load is established, and the power of the constant power load to be controlled is extended into the system state variable. A subsystem to be estimated, including inductor current and load power, is constructed.

[0007] Based on the principles of immersion and invariance, the state to be estimated in the subsystem to be estimated is decomposed into the sum of auxiliary dynamic terms and output dependencies to design a reduced-order state observer; the reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online.

[0008] Based on the deterministic equivalence principle, the backstepping method is adopted. Based on the estimated values ​​of inductor current and load power obtained by the reduced-order state observer, an output voltage tracking controller is designed to generate the control duty cycle of the Buck converter in order to achieve stable tracking control of the output voltage.

[0009] Optionally, a mathematical model of the Buck converter with a constant power load is established, extending the power of the constant power load to be controlled as a system state variable, and constructing a subsystem to be estimated that includes inductor current and load power, including:

[0010] The mathematical model of a Buck converter with a constant power load should satisfy the following equation:

[0011] In the formula, , These represent the inductance parameters and capacitance parameters of the Buck converter, respectively. Indicates inductor current. Indicates capacitor voltage. This indicates the power of the constant power load to be controlled. Indicates the input voltage. This indicates the control duty cycle of the Buck converter;

[0012] By defining system state variables The mathematical model of the Buck converter is converted into a state-space equation form:

[0013] In the formula, This represents the capacitor voltage sampled by the system;

[0014] The output state-space equation of the subsystem to be estimated is redefined as:

[0015] ;

[0016] In the formula, This represents a known regression vector; ;

[0017] The state-space equation of the state to be estimated is redefined as:

[0018] ;

[0019] In the formula, Represents a known function related to the system input and the sampled variables.

[0020] Optionally, based on the principles of immersion and invariance, the state to be estimated in the subsystem to be estimated is decomposed into the sum of auxiliary dynamic terms and output dependencies to design a reduced-order state observer, including:

[0021] A reduced-order state observer should satisfy the following equation:

[0022] ;

[0023] In the formula, Indicates the state to be estimated The estimated value, This represents the auxiliary dynamic term introduced in the design of the reduced-order state observer. This indicates the output dependencies.

[0024] Optionally, the dynamic equation of the auxiliary dynamic term should satisfy the following equation:

[0025] In the formula, Indicates output dependencies The partial derivative with respect to y, Represents a known regression vector The transpose of .

[0026] Optionally, the expression for the output dependencies should satisfy the following equation:

[0027] In the formula, This represents the reduced-order state observer gain matrix. This indicates taking the natural logarithm of the sampled variable.

[0028] Optionally, based on the deterministic equivalence principle, using the backstepping method, and based on the estimated inductor current and load power obtained from the reduced-order state observer, an output voltage tracking controller is designed to generate the control duty cycle of the Buck converter, including:

[0029] Define the output voltage reference value as r, and the output voltage tracking error as... Construct the dynamic equation for voltage tracking error;

[0030] Based on the backstepping method, the inductor current is treated as a pseudo-control input of the voltage loop. An inductor current reference value is designed, and the inductor current tracking error is defined as follows: Construct the dynamic equation for inductor current tracking error;

[0031] Based on the dynamic equations of voltage tracking error and inductor current tracking error, the final output voltage tracking controller is designed using the backstepping method, and the control duty cycle of the Buck converter is obtained.

[0032] Optionally, the dynamic equation for voltage tracking error should satisfy the following equation:

[0033] In the formula, Indicates output voltage tracking error The first reciprocal of .

[0034] Optionally, the inductor current reference value should satisfy the following formula:

[0035] In the formula, Indicates the reference value of inductor current. Indicates the gain of the first output voltage tracking controller. The first derivative of the output voltage reference value. Representing state The estimated value;

[0036] The dynamic equation for inductor current tracking error should satisfy the following:

[0037] In the formula Indicates inductor current tracking error The first reciprocal, The second derivative of the output voltage reference value. and Representing states respectively The first derivative of the estimated value, state The first derivative.

[0038] Optionally, the output voltage tracking controller should satisfy the following expression:

[0039] In the formula, This represents the estimated value of the inductor current tracking error. This indicates the gain of the second output voltage tracking controller. This represents the reduced-order state observer gain. Indicates auxiliary dynamic items One of the elements.

[0040] According to another aspect of the present invention, a sensorless control device for a Buck converter under constant power load in an energy storage system is provided, comprising:

[0041] The subsystem to be estimated construction module is used to establish a mathematical model of a Buck converter with a constant power load, extend the power of the constant power load to be controlled into a system state variable, and construct a subsystem to be estimated that includes inductor current and load power.

[0042] The observer design module is used to decompose the state to be estimated in the subsystem to be estimated into the sum of auxiliary dynamic terms and output dependencies based on the immersion and invariance principle, so as to design a reduced-order state observer; the reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online.

[0043] A voltage tracking controller design module is used to design an output voltage tracking controller based on the inductor current and load power estimates obtained by the reduced-order state observer, according to the deterministic equivalence principle and the backstepping method, and to generate the control duty cycle of the Buck converter to achieve stable tracking control of the output voltage.

[0044] The technical solution provided by this invention expands the unknown constant power load power into a system state variable and designs a reduced-order state observer based on the immersion and invariance principle, achieving synchronous estimation of inductor current and load power solely based on output voltage information. This solution eliminates the control system's dependence on traditional inductor current sensors, reducing system hardware costs and device size, and fundamentally avoiding converter failures caused by current sensor aging or failure, thus improving the operational reliability of the energy storage system. Furthermore, addressing the strong nonlinear bottleneck of existing sensor-limited solutions under constant power loads, an output voltage tracking controller is designed using the backstepping method based on the deterministic equivalence principle, effectively improving the system's output voltage tracking performance. This method only requires acquiring the output voltage to estimate current and load information online, achieving system state monitoring and fault protection without the need for additional current sensors.

[0045] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A flowchart of a sensorless control method for a Buck converter under constant power load in an energy storage system, provided by an embodiment of the present invention;

[0048] Figure 2A general block diagram of a sensorless control method for a Buck converter under constant power load in an energy storage system provided by an embodiment of the present invention;

[0049] Figure 3 This invention provides a control block diagram of a sensorless controller for a Buck converter under constant power load in an energy storage system.

[0050] Figure 4 Simulation results of a sensorless control method for a Buck converter under constant power load in an energy storage system, provided by an embodiment of the present invention;

[0051] Figure 5 Simulation results of a controller for an energy storage system under constant power load step condition provided in an embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram of a sensorless control device for a Buck converter under constant power load in an energy storage system, provided by an embodiment of the present invention.

[0053] Figure 7 This is a schematic diagram of an electronic device for a sensorless control method of a Buck converter under constant power load in an energy storage system, as provided in an embodiment of the present invention. Detailed Implementation

[0054] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0055] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0056] Figure 1This is a flowchart illustrating a sensorless control method for a Buck converter under constant power load in an energy storage system, provided by an embodiment of the present invention. This method can be executed by a sensorless control device for the Buck converter under constant power load in an energy storage system. This device can be implemented in hardware and / or software and can be configured in any electronic device with communication capabilities. See also... Figure 1 The method includes:

[0057] S110. Establish a mathematical model of the Buck converter with a constant power load, extend the power of the constant power load to be controlled into a system state variable, and construct a subsystem to be estimated that includes inductor current and load power.

[0058] Among them, the constant power load power to be controlled refers to the active power consumed by the constant power type load actually connected to the downstream stage of the Buck converter under control during operation. This value is an unknown quantity, which cannot be preset in advance during the controller design stage and cannot be directly measured by sensors during real-time operation of the system. It needs to be estimated online through the subsequently designed reduced-order state observer.

[0059] Specifically, for Buck converters connected to constant power loads in energy storage systems, a continuous time-domain mathematical model that accurately reflects their dynamic characteristics is established using the standard switching cycle averaging method in power electronics, differing from the traditional Buck converter model under resistive loads. Conventional Buck converters have only two inherent state variables: inductor current and capacitor voltage. While the capacitor voltage is measurable, the inductor current is not. Therefore, at the control theory level, the constant power load power P, originally an unknown system parameter, is upgraded from an external parameter of the model to a system state variable alongside the inductor current and capacitor voltage, completing the system's state extension. These two states (inductor current and constant power load power) that cannot be directly measured or obtained by sensors are packaged and reconstructed into an independent subsystem related only to the system's measurable inputs / outputs. The core function of this subsystem is to serve as the design object for subsequent reduced-order state observers, enabling simultaneous estimation of the two unknowns. The input to the subsystem to be estimated is the duty cycle, the output is the capacitor voltage, and the states to be estimated include the unmeasurable inductor current and the unknown constant power load power.

[0060] The purpose of extending the constant power load to be controlled as a system state variable is that, in actual energy storage scenarios, the load power cannot be preset in advance, cannot be directly measured by sensors, and will also dynamically jump. Traditional solutions can only adapt to loads with known power. However, after extending it as a state variable, it can be estimated online by a state observer without knowing its value in advance. In the original model, the differential equation of the capacitor voltage contains two unknowns: inductor current and load power. Moreover, the load power and capacitor voltage are nonlinearly coupled, making it impossible to directly design an observer. After extending it as a state variable, it can be treated in a unified manner with the inductor current, thus solving the nonlinearity problem.

[0061] By constructing the subsystem to be estimated, it was demonstrated that the inductor current and load power in two unmeasurable states can be estimated using only the single measurable capacitor voltage. This proves the feasibility of sensorless control at the model level, highlighting the core innovation of this invention: "few sensors." The reconstructed subsystem's state equations contain only measurable terms and no unknown coupling terms, solving the observer design challenges posed by the nonlinearity of constant power loads and unknown power, thus making subsequent immersion and invariant observer designs feasible.

[0062] S120. Based on the immersion and invariance principle, the state to be estimated in the subsystem to be estimated is decomposed into the sum of auxiliary dynamic terms and output dependencies to design a reduced-order state observer; wherein, the reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online.

[0063] The output dependency term is entirely dependent on the measurable output sample value of the system and is independent of any unknown states or dynamic changes; hence, it is called the output dependency term. Its function is to match the nonlinearity of the constant power load and directly offset the nonlinear characteristics of the system. The auxiliary dynamic term is an artificially introduced auxiliary variable with its own independent dynamic differential equation. It is the only dynamic element in the observer and is therefore called the auxiliary dynamic term. Its core function is to ensure that the estimation error converges to zero through a user-defined dynamic law, allowing the estimated value to track the true value.

[0064] The reason for this decomposition is that traditional observers are designed by directly designing differential equations for the estimated values ​​and relying on linear feedback correction based on the output error. This approach is only suitable for linear systems. When faced with the nonlinear characteristics of this scenario, either linearization is required to introduce errors, or global stability cannot be guaranteed. However, by decomposing the system into "auxiliary dynamic terms + output dependencies", we delegate the adaptation of nonlinear characteristics to the output dependencies and the convergence control of the estimation error to the auxiliary dynamic terms. This perfectly decouples the two challenges of "nonlinear adaptation" and "stability design", ensuring stable convergence of the observer under all operating conditions without the need for linearization.

[0065] The original Buck converter's complete state-space model is a third-order system. Traditional full-order observers require designing a third-order dynamic system and estimating all three states. However, in this invention, the capacitor voltage can be directly sampled and measured, eliminating the need for estimation. We only need to design observers for the remaining two unmeasurable states. The observer's dynamic order is second-order, much lower than the original system's order, hence the name "reduced-order state observer." The aforementioned state decomposition method perfectly suits reduced-order design: it eliminates the need to handle the dynamics of measurable states, focusing only on the unmeasurable states to be estimated. This avoids redundant calculations in full-order observers and improves the observer's dynamic response speed.

[0066] The reduced-order state observer operates as follows: the controller samples the output capacitor voltage in real time, synchronously obtains the duty cycle of its own output, first calculates the output dependency, then updates it in real time through the differential equation of the auxiliary dynamic term, and finally directly calculates the estimated values ​​of the inductor current and load power, without the need for any current sensor or power detection device.

[0067] The observer designed using this method can simultaneously estimate the inductor current and unknown load power online using only a single voltage sample, completely eliminating the dependence on current sensors. It directly adapts to the nonlinear characteristics of constant power loads without the need for linearization approximation. Even under conditions such as load power step changes and voltage fluctuations, it can still ensure that the estimation error converges globally to 0. The reduced-order design significantly reduces the computational load and is easy to implement in engineering. At the same time, it avoids the redundant design of full-order observers and improves the dynamic response speed of the system.

[0068] S130. Based on the deterministic equivalence principle, the backstepping method is adopted. Based on the estimated values ​​of inductor current and load power obtained by the reduced-order state observer, the output voltage tracking controller is designed to generate the control duty cycle of the Buck converter in order to achieve stable tracking control of the output voltage.

[0069] In this scheme, the inductor current is directly measured without sensors, and the constant power load power P is unknown throughout the process; both are unmeasurable quantities of the system. The preceding reduced-order observer obtains estimates of both values ​​simultaneously only by sampling the output voltage. Based on the deterministic equivalence principle, the estimated inductor current is directly used to replace the actual inductor current throughout the entire output voltage tracking controller design process, achieving sensorless current closed-loop control; the estimated load power is directly used to replace the actual load power P, achieving feedforward compensation for unknown loads without prior knowledge of the load power. Using the backstepping method, with stable output voltage tracking as the core objective, the voltage tracking error is defined, and the inductor current is considered as a virtual control input to the voltage loop, designing a reference value for the inductor current. The inductor current tracking error is also defined, and the Buck converter's duty cycle is used as the final actual control input to derive the final control law, i.e., the final Buck converter switching duty cycle signal. The controller designed in this scheme outputs a duty cycle signal that, after SPWM modulation, directly drives the Buck converter's power switching transistor, completing physical-level closed-loop control. The ultimate control objective of this solution is always to ensure stable tracking of the Buck converter output voltage: to ensure that the output capacitor voltage accurately follows the preset reference voltage, maintaining steady-state stability without steady-state error and dynamic stability without significant drops / overshoots, regardless of input voltage fluctuations, load power steps, or changes in operating conditions. This is the core requirement for DC voltage conversion in energy storage systems.

[0070] The technical solution provided by this invention expands the unknown constant power load power into a system state variable and designs a reduced-order state observer based on the immersion and invariance principle, achieving synchronous estimation of inductor current and load power solely based on output voltage information. This solution eliminates the control system's dependence on traditional inductor current sensors, reducing system hardware costs and device size, and fundamentally avoiding converter failures caused by current sensor aging or failure, thus improving the operational reliability of the energy storage system. Furthermore, addressing the strong nonlinear bottleneck of existing sensor-limited solutions under constant power loads, an output voltage tracking controller is designed using the backstepping method based on the deterministic equivalence principle, effectively improving the system's output voltage tracking performance. This method only requires acquiring the output voltage to estimate current and load information online, achieving system state monitoring and fault protection without the need for additional current sensors.

[0071] Optionally, step S110 specifically includes:

[0072] The mathematical model of a Buck converter with a constant power load should satisfy the following equation:

[0073] In the formula, , These represent the inductance parameters and capacitance parameters of the Buck converter, respectively. Indicates inductor current. Indicates capacitor voltage. This indicates the power of the constant power load to be controlled. Indicates the input voltage. This indicates the control duty cycle of the Buck converter;

[0074] By defining system state variables The mathematical model of the Buck converter is converted into a state-space equation form:

[0075] In the formula, This represents the capacitor voltage sampled by the system;

[0076] The output state-space equation of the subsystem to be estimated is redefined as:

[0077] ;

[0078] In the formula, This represents a known regression vector; ;

[0079] The state-space equation of the state to be estimated is redefined as:

[0080] ;

[0081] In the formula, Represents a known function related to the system input and the sampled variables.

[0082] Optionally, step S120 specifically includes:

[0083] A reduced-order state observer should satisfy the following equation:

[0084] ;

[0085] In the formula, Indicates the state to be estimated The estimated value, This represents the auxiliary dynamic term introduced in the design of the reduced-order state observer. This indicates the output dependencies.

[0086] The dynamic equation for the auxiliary dynamic term should satisfy the following equation:

[0087] In the formula, Indicates output dependencies The partial derivative with respect to y, Represents a known regression vector The transpose of .

[0088] The expression for output dependencies should satisfy the following equation:

[0089] In the formula, This represents the reduced-order state observer gain matrix. This indicates taking the natural logarithm of the sampled variable.

[0090] Optionally, step S130 specifically includes:

[0091] Define the output voltage reference value as r, and the output voltage tracking error as... A dynamic equation for voltage tracking error is constructed.

[0092] The dynamic equation for voltage tracking error should satisfy the following equation:

[0093] In the formula, Indicates output voltage tracking error The first reciprocal of .

[0094] Based on the backstepping method, the inductor current is treated as a pseudo-control input of the voltage loop. An inductor current reference value is designed, and the inductor current tracking error is defined as follows: A dynamic equation for the inductor current tracking error is constructed.

[0095] The inductor current reference value should satisfy the following formula:

[0096] In the formula, Indicates the reference value of inductor current. Indicates the gain of the first output voltage tracking controller. The first derivative of the output voltage reference value. Representing state The estimated value;

[0097] The dynamic equation for inductor current tracking error should satisfy the following:

[0098] In the formula Indicates inductor current tracking error The first reciprocal, The second derivative of the output voltage reference value. and Representing states respectively The first derivative of the estimated value, state The first derivative.

[0099] Based on the dynamic equations of voltage tracking error and inductor current tracking error, the final output voltage tracking controller is designed using the backstepping method, and the control duty cycle of the Buck converter is obtained.

[0100] The output voltage tracking controller should satisfy the following expression:

[0101] In the formula, This represents the estimated value of the inductor current tracking error. This indicates the gain of the second output voltage tracking controller. This represents the reduced-order state observer gain. Indicates auxiliary dynamic items One of the elements.

[0102] Figure 2 This is a general block diagram of a sensorless control method for a Buck converter under constant power load in an energy storage system, provided by an embodiment of the present invention. Figure 3 This is a control block diagram of a sensorless controller for a Buck converter under constant power load in an energy storage system, provided as an embodiment of the present invention. Figure 4 The simulation results of a sensorless control method for a Buck converter under constant power load in an energy storage system, as provided in this embodiment of the invention, show that the controller can accurately track the voltage even under unknown constant power load conditions. To ensure that the known regression vector of the observer satisfies the continuous excitation condition and thus ensures the convergence of the observation error, this scheme superimposes a weak sinusoidal signal onto the reference voltage, which does not affect the overall control performance of the system. Figure 5 The simulation results show that the controller of an energy storage system under constant power load step condition is provided in an embodiment of the present invention. The results show that the proposed solution has good dynamic performance; under load step condition, the voltage does not drop significantly, and the load current doubles.

[0103] The technical solution provided by this invention first establishes a mathematical model of the switching cycle average of a Buck converter with a constant power load, and extends the unknown load power into a system state variable, constructing a subsystem to be estimated that includes inductor current and load power, thus providing a model basis for the design of a sensorless controller. Based on this, a reduced-order state observer is designed based on the immersion and invariance principle. By introducing auxiliary variables, the state to be estimated is expressed as the sum of auxiliary dynamic terms and output dependencies, and the corresponding partial differential equations are further solved to obtain analytical expressions for the auxiliary variables. This observer only needs to collect output voltage information to simultaneously achieve online estimation of inductor current and unknown load power, avoiding the dependence on current sensors in traditional methods. Furthermore, based on the deterministic equivalence principle, using the estimated inductor current and load power values ​​obtained by the observer, an output voltage tracking controller is designed using the backstepping method, enabling the Buck converter to maintain good voltage regulation capability and dynamic response performance under constant power load conditions. The significant advantage of this solution is that it can achieve system status monitoring, load power estimation and fault protection without the need to configure inductor current sensors. While effectively reducing hardware costs and device size, it improves the reliability, stability and dynamic performance of the energy storage converter system under unknown constant power load conditions.

[0104] Figure 6 This is a schematic diagram of a sensorless control device for a Buck converter under constant power load in an energy storage system, provided in an embodiment of the present invention. (See attached diagram.) Figure 6 The device includes: a subsystem construction module 210 to be estimated, an observer design module 220, and a voltage tracking controller design module 230.

[0105] The subsystem to be estimated construction module 210 is used to establish a mathematical model of a Buck converter with a constant power load, extend the power of the constant power load to be controlled into a system state variable, and construct a subsystem to be estimated that includes inductor current and load power.

[0106] The observer design module 220 is used to decompose the state to be estimated in the subsystem to be estimated into the sum of auxiliary dynamic terms and output dependencies based on the immersion and invariance principle, so as to design a reduced-order state observer; the reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online.

[0107] The voltage tracking controller design module 230 is used to design the output voltage tracking controller based on the deterministic equivalence principle, using the backstepping method and the estimated values ​​of inductor current and load power obtained by the reduced-order state observer, and to generate the control duty cycle of the Buck converter in order to achieve stable tracking control of the output voltage.

[0108] The sensorless control device for a Buck converter under constant power load in an energy storage system provided in this embodiment of the invention can execute the sensorless control method for a Buck converter under constant power load in an energy storage system provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of executing the method.

[0109] Figure 7 This is a schematic diagram of an electronic device for a sensorless control method of a Buck converter under constant power load in an energy storage system, provided as an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0110] like Figure 7 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 and a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded into the RAM 13 from storage unit 18. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, the ROM 12, and the RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0111] Multiple components in electronic device 10 are connected to input / output I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of monitors, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0112] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as a sensorless control method for a Buck converter under constant power load in an energy storage system.

[0113] In some embodiments, the sensorless control method for a Buck converter under constant power load in an energy storage system can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or mounted on electronic device 10 via read-only memory ROM 12 and / or communication unit 19. When the computer program is loaded into random access memory RAM 13 and executed by processor 11, one or more steps of the sensorless control method for a Buck converter under constant power load in an energy storage system described above can be performed. Alternatively, in other embodiments, processor 11 can be configured in any other suitable manner to perform the sensorless control method for a Buck converter under constant power load in an energy storage system.

[0114] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transferring data and instructions to the storage system, the at least one input device, and the at least one output device.

[0115] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0116] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0117] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device for displaying information to a user; and a keyboard and pointing device through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with a user; for example, feedback provided to the user can be any form of sensory feedback; and input from the user can be received in any form.

[0118] The systems and technologies described herein can be implemented in computing systems that include backend components, middleware components, or frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium. Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0119] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0120] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0121] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A sensorless control method for a Buck converter under constant power load in an energy storage system, characterized in that, include: A mathematical model of a Buck converter with a constant power load is established, and the power of the constant power load to be controlled is extended into the system state variable. A subsystem to be estimated, including inductor current and load power, is constructed. Based on the principles of immersion and invariance, the state to be estimated in the subsystem to be estimated is decomposed into the sum of auxiliary dynamic terms and output dependencies in order to design a reduced-order state observer. The reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online. Based on the deterministic equivalence principle, the backstepping method is adopted. Based on the estimated values ​​of inductor current and load power obtained by the reduced-order state observer, an output voltage tracking controller is designed to generate the control duty cycle of the Buck converter in order to achieve stable tracking control of the output voltage.

2. The method according to claim 1, characterized in that, A mathematical model of a Buck converter with a constant power load is established, extending the power of the constant power load to be controlled as a system state variable. A subsystem to be estimated, including inductor current and load power, is constructed: The mathematical model of a Buck converter with a constant power load should satisfy the following equation: In the formula, , These represent the inductance parameters and capacitance parameters of the Buck converter, respectively. Indicates inductor current. Indicates capacitor voltage. This indicates the power of the constant power load to be controlled. Indicates the input voltage. This indicates the control duty cycle of the Buck converter; By defining system state variables The mathematical model of the Buck converter is converted into a state-space equation form: In the formula, This represents the capacitor voltage sampled by the system; The output state-space equation of the subsystem to be estimated is redefined as: ； In the formula, This represents a known regression vector; ; The state-space equation of the state to be estimated is redefined as: ； In the formula, Represents a known function related to the system input and the sampled variables.

3. The method according to claim 2, characterized in that, Based on the principles of immersion and invariance, the state to be estimated in the subsystem is decomposed into the sum of auxiliary dynamic terms and output dependencies to design a reduced-order state observer, including: A reduced-order state observer should satisfy the following equation: ； In the formula, Indicates the state to be estimated The estimated value, This represents the auxiliary dynamic term introduced in the design of the reduced-order state observer. This indicates the output dependencies.

4. The method according to claim 3, characterized in that, The dynamic equation for the auxiliary dynamic term should satisfy the following equation: In the formula, Indicates output dependencies The partial derivative with respect to y, Represents a known regression vector The transpose of .

5. The method according to claim 3, characterized in that, The expression for output dependencies should satisfy the following equation: In the formula, This represents the reduced-order state observer gain matrix. This indicates taking the natural logarithm of the sampled variable.

6. The method according to claim 1, characterized in that, Based on the deterministic equivalence principle, and using the backstepping method, an output voltage tracking controller is designed based on the estimated inductor current and load power obtained from the reduced-order state observer. The control duty cycle of the Buck converter includes: Define the output voltage reference value as r, and the output voltage tracking error as... Construct the dynamic equation for voltage tracking error; Based on the backstepping method, the inductor current is treated as a pseudo-control input of the voltage loop. An inductor current reference value is designed, and the inductor current tracking error is defined as follows: Construct the dynamic equation for inductor current tracking error; Based on the dynamic equations of voltage tracking error and inductor current tracking error, the final output voltage tracking controller is designed using the backstepping method, and the control duty cycle of the Buck converter is obtained.

7. The method according to claim 6, characterized in that, The dynamic equation for voltage tracking error should satisfy the following: In the formula, Indicates output voltage tracking error The first reciprocal of .

8. The method according to claim 6, characterized in that, The inductor current reference value should satisfy the following formula: In the formula, Indicates the reference value of inductor current. Indicates the gain of the first output voltage tracking controller. The first derivative of the output voltage reference value. Representing state The estimated value; The dynamic equation for inductor current tracking error should satisfy the following: In the formula Indicates inductor current tracking error The first reciprocal, The second derivative of the output voltage reference value. and Representing states respectively The first derivative of the estimated value, state The first derivative.

9. The method according to claim 6, characterized in that, The output voltage tracking controller should satisfy the following expression: In the formula, This represents the estimated value of the inductor current tracking error. This indicates the gain of the second output voltage tracking controller. This represents the reduced-order state observer gain. Indicates auxiliary dynamic items One of the elements.

10. A sensorless control device for a Buck converter under constant power load in an energy storage system, characterized in that, include: The subsystem to be estimated construction module is used to establish a mathematical model of a Buck converter with a constant power load, extend the power of the constant power load to be controlled into a system state variable, and construct a subsystem to be estimated that includes inductor current and load power. The observer design module is used to decompose the state to be estimated in the subsystem to be estimated into the sum of auxiliary dynamic terms and output dependencies based on the principles of immersion and invariance, so as to design a reduced-order state observer. The reduced-order state observer only needs to collect the output capacitor voltage signal of the Buck converter to simultaneously estimate the inductor current and load power online. A voltage tracking controller design module is used to design an output voltage tracking controller based on the inductor current and load power estimates obtained by the reduced-order state observer, according to the deterministic equivalence principle and the backstepping method, and to generate the control duty cycle of the Buck converter to achieve stable tracking control of the output voltage.

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