Adaptive passive control method for dc buck converter with zip load

Abstract

The application discloses a kind of DC voltage-reducing converter adaptive passive control methods with ZIP load, the method proposes a passive controller, even in the absence of load accurate information can guarantee the stability of output voltage.Then, a kind of immersion and invariant observer is designed for online estimation input voltage.Adaptive passive control to DC voltage-reducing converter with ZIP load is realized by introducing the estimated value into the passive controller.The proposed controller can guarantee the exponential convergence of closed-loop system without load, input voltage information.Finally, the effectiveness of the controller is verified by simulation.The DC voltage-reducing converter adaptive passive control method with ZIP load provided by the application can guarantee the local asymptotic convergence of closed-loop system, and has good control performance, strong robustness and anti-interference.

Description

Technical Field

[0001] This invention relates to an adaptive passive control method for a DC-DC buck converter with a ZIP load, specifically to a passive controller and an immersion and invariance observer, which are combined to form an adaptive passive control method, belonging to the field of power electronic converter technology. Background Technology

[0002] In power systems, DC-DC converters are frequently used as interfaces between power sources and loads, providing a suitable operating environment for electrical equipment. The DC-DC buck converter is one of the fundamental DC-DC converters, used to reduce the voltage at the output port, and its control performance directly affects the power quality of the system. Therefore, the control problem of buck converters has attracted much attention from scholars, and a large number of research results have been produced on the control problem of DC-DC buck converters.

[0003] It is important to note that most current research focuses on DC-DC converters with resistive loads. However, with technological advancements, power systems are becoming increasingly complex, and electrical equipment is becoming more diverse, leading to the widespread adoption of ZIP (Zone-in-Place) loads. A ZIP load is formed by parallel connection of a resistive load, a constant power load (CPL), and a constant current load (CCL). Its structure is more complex and introduces nonlinearity and negative impedance characteristics into the system. This significantly impacts system stability and greatly increases system complexity.

[0004] Currently, research results addressing these issues are very scarce. Existing technologies have proposed a passive controller to solve the control problem of boost converters with ZIP loads; however, the controller uses differential state information, which makes the closed-loop system extremely sensitive to disturbances and exhibits poor anti-interference capabilities.

[0005] Therefore, the control problem of DC-DC buck converters with ZIP loads is a more challenging and urgent problem to be solved. Summary of the Invention

[0006] Objective: To overcome the control problems existing in the prior art for DC-DC buck converters with ZIP loads, this invention provides an adaptive passive control method for DC-DC buck converters with ZIP loads. Combining immersion and invariant observers, an adaptive passive controller is proposed. It can guarantee the local asymptotic convergence of the closed-loop system without using precise load and input voltage information or differential information. It has good control performance and strong robustness and anti-interference ability.

[0007] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] An adaptive passive control method for a DC-DC buck converter with a ZIP load includes the following steps:

[0009] Step 1: Obtain the mathematical model of the DC-DC buck converter with ZIP load, and convert the mathematical model into a port Hamiltonian system.

[0010] Step 2: Construct the input voltage observer.

[0011] Step 3: Construct a passive controller for the Hamiltonian system through the port Hamiltonian system.

[0012] Step 4: Obtain the real-time input voltage observation data of the closed-loop system of the DC-DC buck converter with ZIP load based on the input voltage observer, and obtain the adaptive passive control law based on the real-time input voltage observation data and the passive controller of the Hamiltonian system.

[0013] Step 5: Input the adaptive passive control law into the PWM module to obtain the DC-DC buck converter switching transistor drive signal with fixed frequency and controllable duty cycle, thus realizing the control of the DC-DC buck converter with ZIP load.

[0014] As a preferred embodiment, the closed-loop system of the DC-DC buck converter with ZIP load includes: a power supply, a DC-DC buck converter, and a ZIP load. The power supply is connected to the input terminal of the DC-DC buck converter, and the ZIP load is connected to the output terminal of the DC-DC buck converter.

[0015] As a preferred embodiment, the mathematical model calculation formula is as follows:

[0016]

[0017] Where R is the resistance component of the ZIP load, i is the current component of the ZIP load, P is the power component of the ZIP load, E is the input voltage of the DC-DC buck converter, d is the duty cycle of the DC-DC buck converter switching control signal, C is the nominal value of the DC-DC buck converter capacitor, L is the nominal value of the DC-DC buck converter inductor, x1 is the inductor current in the DC-DC buck converter, and x2 is the output voltage in the DC-DC buck converter. Let x1 be the first derivative with respect to time. Let x2 be the first derivative with respect to time.

[0018] As a preferred embodiment, the formula for calculating the port Hamiltonian system is as follows:

[0019]

[0020] in, This is a storage function for the Hamiltonian system.

[0021] As the preferred solution

[0022] As a preferred embodiment, the input voltage observer is calculated using the following formula:

[0023]

[0024] in, This represents the input voltage observer state, where β is the input voltage observer gain. For input voltage observation

[0025] Time data value, Input voltage observer state The first derivative with respect to time, x1 is the inductor current in the DC-DC buck converter, x2 is the output voltage in the DC-DC buck converter, d is the duty cycle of the switching control signal of the DC-DC buck converter, and L is the nominal value of the inductor of the DC-DC buck converter.

[0026] As a preferred embodiment, step 3 specifically includes the following steps:

[0027] Step 3.1: Convert the port Hamiltonian system into a closed-loop Hamiltonian system.

[0028] Step 3.2: Construct the desired closed-loop Hamiltonian system.

[0029] Step 3.3: Based on the closed-loop Hamiltonian system and the desired closed-loop Hamiltonian system, construct the passive controller for the Hamiltonian system.

[0030] As a preferred embodiment, the calculation formula for the closed-loop Hamiltonian system is as follows:

[0031]

[0032] in, u is the input to the closed-loop Hamiltonian system, and H1(x1,x2) is the storage function of the closed-loop Hamiltonian system. This represents the desired output voltage.

[0033] The desired closed-loop Hamiltonian system is calculated using the following formula:

[0034]

[0035] Where x is the state vector, x = [x1, x2, x3] c ] T x c This represents the passive controller state, where α is the interconnect gain and r is the damping gain. Let x1 be the first derivative with respect to time. Let x1 be the first derivative with respect to time. For xc The first derivative with respect to time, H d (x) is the storage function of the desired closed-loop Hamiltonian system.

[0036] The passive controller of the Hamiltonian system is calculated using the following formula:

[0037]

[0038]

[0039] in, For passive controller state x c The first derivative with respect to time.

[0040] As the preferred solution

[0041] in,

[0042] As the preferred solution

[0043] in, k is the passive controller gain.

[0044] As a preferred embodiment, step 4 specifically includes the following steps:

[0045] Step 4.1: Calculate the real-time data value of the input voltage observation based on the input voltage observer.

[0046] Step 4.2: Apply the formula Substituting the passive controller of the Hamiltonian system into the equation, we obtain the passive control law d, calculated as follows:

[0047]

[0048] Step 4.3: Transfer the real-time voltage observation data values As the input voltage term of the passive control law, the adaptive passive control law is obtained. The calculation formula is as follows:

[0049]

[0050] As a preferred option, when At that time, adaptive passive control law This makes the closed-loop system of the DC-DC buck converter with ZIP load asymptotically stable.

[0051] As a preferred option, β > 0.

[0052] As a preferred option, α > 0, r > 0, k > 0.

[0053] Beneficial Effects: This invention provides an adaptive passive control method for a DC-DC buck converter with a ZIP load. Considering the unknown load and input voltage, this paper proposes an adaptive passive controller to stabilize the DC-DC buck converter with a ZIP load. Furthermore, based on immersion and invariance theory, an input voltage observer is proposed to estimate the input voltage in real time and adjust relevant parameters in the controller, thereby achieving adaptive passive control for the DC-DC buck converter with a ZIP load.

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] (1) This invention proposes a passive controller to stabilize a DC-DC buck converter with a ZIP load. It can guarantee the local exponential convergence of the closed-loop system without load information. It can still achieve reliable performance even when the load is unknown. It has a simple structure and is easy to apply in engineering.

[0056] (2) An observer based on immersion and invariance theory is proposed, which realizes real-time observation of input voltage and the observation error can converge exponentially to zero.

[0057] (3) By combining the proposed input voltage observer and passive controller, adaptive passive control of DC converter with unknown ZIP load is realized. The proposed controller does not require accurate information on load and input voltage, and can effectively suppress the influence of load and input voltage disturbances on the system. Attached Figure Description

[0058] Figure 1 This is a circuit diagram of a DC-DC buck converter with a ZIP load.

[0059] Figure 2 This is a structural diagram of an adaptive passive controller for a DC-DC buck converter with an unknown ZIP load, according to the present invention.

[0060] Figure 3 The present invention relates to the response curves of the closed-loop system under different controller gains, considering a step change in the reference output from 20V to 15V, with observer parameter β = 1000, under the controller of the present invention.

[0061] Figure 4 Under the controller of this invention, considering a step change in input voltage from 22V to 30V, with controller parameters α=10, k=1.5, and r=1.5, the response curves of the closed-loop system under different observer gains are selected.

[0062] Figure 5Under the controller of this invention, considering the step change of the load, the resistance component, the CPL component, the CCL component, and the controller parameters α=10, k=1.5, r=1.5, the response curve of the closed-loop system under different observer gains is selected. Detailed Implementation

[0063] The present invention will be further described below with reference to specific embodiments.

[0064] A closed-loop system of a DC-DC buck converter with a ZIP load includes: a power supply E, a DC-DC buck converter, and a ZIP load.

[0065] An adaptive passive control method for a DC-DC buck converter with a ZIP load, the structure of which is as follows: Figure 2 As shown, the specific implementation steps are as follows:

[0066] Step 1: From Figure 1 As shown, a mathematical model of a DC-DC buck converter with a ZIP load is established based on the circuit of the ZIP load.

[0067] Step 2: In practical engineering, the application environment of DC-DC converters is complex and variable, inevitably leading to input voltage disturbances. To suppress the negative impact of input voltage step changes on DC-DC buck converter systems with ZIP loads, an input voltage observer is used to analyze and process the inductor current, output voltage, and duty cycle data of the DC-DC buck converter. This data is then used to estimate and output the real-time input voltage observation value, and its observation error can converge exponentially to zero.

[0068] Step 3: To overcome the instability caused by load fluctuations in actual engineering, a passive controller is used. Without using load data, the controller can output an adaptive passive control law (duty cycle) in real time based solely on the inductance data, inductance current, output voltage data of the DC-DC buck converter, and the real-time data value of the input voltage observation, ensuring that the output voltage converges exponentially to the desired value.

[0069] Step 4: The adaptive passive control law obtained in Step 3 is processed using a PWM module to obtain a DC-DC buck converter switching transistor drive signal with a fixed frequency and controllable duty cycle. By adjusting the duty cycle, the control of the DC-DC buck converter with ZIP load is realized.

[0070] Step 1, the specific steps are as follows:

[0071] Step 11: Using the inductor current in the DC-DC buck converter as the state variable x1 in the mathematical model and the output voltage in the DC-DC buck converter as the state variable x2 in the mathematical model, construct a large-signal state-space average model as the mathematical model of the DC-DC buck converter with ZIP load. The calculation formula is as follows:

[0072]

[0073] Where R is the resistance component of the ZIP load, i is the current component of the ZIP load, P is the power component of the ZIP load, E is the input voltage of the DC-DC buck converter, d is the duty cycle of the DC-DC buck converter switching control signal, which is also used as the control input of this invention, C is the nominal value of the DC-DC buck converter capacitor, and L is the nominal value of the DC-DC buck converter inductor. Let x1 be the first derivative with respect to time. Let x2 be the first derivative with respect to time.

[0074] Step 12, the large-signal state-space averaging model is converted into a port Hamiltonian system as follows:

[0075]

[0076]

[0077] in, H(x1,x2) is the storage function of the Hamiltonian system, x1 is the inductor current in the DC-DC buck converter, x2 is the output voltage in the DC-DC buck converter, C is the nominal value of the capacitor in the DC-DC buck converter, L is the nominal value of the inductor in the DC-DC buck converter, R is the resistance component of the ZIP load, i is the current component of the ZIP load, P is the power component of the ZIP load, E is the input voltage of the DC-DC buck converter, and d is the duty cycle of the switching control signal of the DC-DC buck converter.

[0078] Step 2, the specific steps are as follows:

[0079] Based on immersion and invariance theory, the input voltage observer calculation formula is as follows:

[0080]

[0081] in, This represents the input voltage observer state, where β is the input voltage observer gain, and β > 0. This refers to real-time data observations of the input voltage. Input voltage observer state The first derivative with respect to time, x1 is the inductor current in the DC-DC buck converter, x2 is the output voltage in the DC-DC buck converter, d is the duty cycle of the switching control signal of the DC-DC buck converter, and L is the nominal value of the inductor of the DC-DC buck converter.

[0082] Step 3, the specific steps are as follows:

[0083] The design steps for an adaptive passive controller are as follows:

[0084] Step 31, given the desired output voltage as To simplify the expression, we define intermediate quantities. The port Hamiltonian system obtained in step 1 is further converted into a closed-loop Hamiltonian system. The calculation formula for the closed-loop Hamiltonian system is as follows:

[0085]

[0086]

[0087] in, u is the input to the closed-loop Hamiltonian system, and its relationship with the duty cycle d can be expressed as follows: H1(x1,x2) is the storage function of the closed-loop Hamiltonian system. Let x1 be the first derivative with respect to time. x2 is the first derivative of x2 with respect to time, x1 is the inductor current in the DC-DC buck converter, x2 is the output voltage in the DC-DC buck converter, d is the duty cycle of the switching control signal of the DC-DC buck converter, L is the nominal value of the inductor of the DC-DC buck converter, P is the power component of the ZIP load, C is the nominal value of the capacitor of the DC-DC buck converter, R is the resistance component of the ZIP load, i is the current component of the ZIP load, and E is the input voltage of the DC-DC buck converter.

[0088] Step 32, design the desired closed-loop Hamiltonian system, the calculation formula is as follows:

[0089]

[0090]

[0091] Where x is the state vector, x = [x1, x2, x3] c ] T x c For the passive controller state, α is the interconnection gain (α > 0), r is the damping gain (r > 0), and k is the controller gain (k > 0). Let x1 be the first derivative with respect to time. Let x2 be the first derivative with respect to time. For x c The first derivative with respect to time, H d (x) is the storage function of the desired closed-loop Hamiltonian system. x1 represents the inductor current in the DC-DC buck converter, and x2 represents the output voltage in the DC-DC buck converter. Let d be the desired output voltage, d be the duty cycle of the DC-DC buck converter switching control signal, L be the nominal value of the DC-DC buck converter inductor, P be the power component of the ZIP load, C be the nominal value of the DC-DC buck converter capacitor, R be the resistance component of the ZIP load, i be the current component of the ZIP load, and E be the input voltage of the DC-DC buck converter.

[0092] Based on the closed-loop Hamiltonian system obtained in step 31 and the desired closed-loop Hamiltonian system obtained in step 32, the calculation formula for the passive controller of the above Hamiltonian system with a ZIP load DC-DC buck converter is as follows:

[0093]

[0094]

[0095] in, For passive controller state x c The first derivative with respect to time, where x2 is the output voltage in the DC-DC buck converter. Let α be the desired output voltage, α be the interconnect gain (α > 0), r be the damping gain (r > 0), k be the passive controller gain (k > 0), u be the input of the closed-loop Hamiltonian system, and x1 be the inductor current in the DC-DC buck converter.

[0096] Step 33: Based on the relationship between the input u and the duty cycle d of the closed-loop Hamiltonian system in Step 21, the passive control law of the passive controller can be obtained. The calculation formula is as follows:

[0097]

[0098] when At that time, the above passive control law can guarantee the asymptotic stability of the closed-loop system with the ZIP load DC buck converter.

[0099] Use the input voltage obtained in step (2) to observe real-time data values. The input voltage term of the adaptive passive control law yields the adaptive passive controller, calculated as follows:

[0100]

[0101] This is the adaptive passive control law after substituting the real-time data values ​​of the input voltage observation.

[0102] The adaptive passive controller is constructed without using load information and incorporates an observer, eliminating its dependence on precise input voltage information. The adaptive passive controller can achieve control output using only state information and inductance values, thus it is insensitive to parameter perturbations and exhibits strong robustness. Simulation results will follow to demonstrate this.

[0103] To verify the effectiveness of the proposed adaptive passive controller, simulations were performed on the MATLAB / Simulink platform. Figure 2 The control principle diagram of the proposed controller is shown below. The system parameters selected for simulation are shown in Table 1.

[0104] Table 1

[0105]

[0106]

[0107] First, consider a step change in the reference output to test the tracking performance. Figure 3 The response curves of the closed-loop system are shown when different controller parameters are selected. It can be seen that the output voltage can quickly and accurately track the reference value, and appropriately increasing the values ​​of α, k, and r can effectively improve the convergence speed. Figure 4 The response curve of the closed-loop system when the input voltage changes abruptly is shown. It can be seen that the observer has a good tracking effect on the actual value of the output voltage, and the larger the β is, the faster the tracking speed. Figure 5 The response curve of the closed-loop system when the load undergoes a sudden change is shown. From... Figure 4 , 5 It is easy to see that the output voltages all regained tracking of the reference output after a small, short-term disturbance. Therefore, under the controller of this invention, the closed-loop system has strong robustness and can effectively suppress the adverse effects of load and input voltage disturbances on the system.

[0108] Simulation results show that the controller of the present invention has good control performance for DC buck converters with ZIP loads, and can effectively suppress the interference caused by load and input voltage changes to the system, and has strong robustness and anti-interference ability.

[0109] This invention discloses an adaptive passive control method for a DC-DC buck converter with a ZIP load, where the ZIP load is a load formed by a resistive load, a constant power load, and a constant current load connected in parallel. The method proposes a passive controller that ensures output voltage stability even without precise load information. Then, an immersion-invariant observer is designed for online estimation of the input voltage. By incorporating the estimated value into the passive controller, adaptive passive control of the DC-DC buck converter with the ZIP load is achieved. The proposed controller guarantees exponential convergence of the closed-loop system without requiring load or input voltage information. Finally, simulations verify the effectiveness of the controller.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive passive control method for a DC-DC buck converter with a ZIP load, characterized in that: Includes the following steps: Step 1: Obtain the mathematical model of the DC-DC buck converter with ZIP load, and convert the mathematical model into a port Hamiltonian system; Step 2: Construct the input voltage observer; Step 3: Construct a passive controller for the Hamiltonian system using the port Hamiltonian system; Step 4: Obtain the real-time input voltage observation data of the closed-loop system of the DC-DC buck converter with ZIP load based on the input voltage observer, and obtain the adaptive passive control law based on the real-time input voltage observation data and the passive controller of the Hamiltonian system. Step 5: Input the adaptive passive control law into the PWM module to obtain the DC-DC buck converter switching transistor drive signal with fixed frequency and controllable duty cycle, thus realizing the control of the DC-DC buck converter with ZIP load.

2. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 1, characterized in that: The closed-loop system of the DC-DC buck converter with ZIP load includes: a power supply, a DC-DC buck converter, and a ZIP load. The power supply is connected to the input terminal of the DC-DC buck converter, and the ZIP load is connected to the output terminal of the DC-DC buck converter.

3. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 1, characterized in that: The mathematical model calculation formula is as follows: Where R is the resistance component of the ZIP load, i is the current component of the ZIP load, P is the power component of the ZIP load, E is the input voltage of the DC-DC buck converter, d is the duty cycle of the DC-DC buck converter switching control signal, C is the nominal value of the DC-DC buck converter capacitor, L is the nominal value of the DC-DC buck converter inductor, x1 is the inductor current in the DC-DC buck converter, and x2 is the output voltage in the DC-DC buck converter. Let x1 be the first derivative with respect to time. Let x2 be the first derivative with respect to time.

4. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 3, characterized in that: The formula for calculating the port Hamiltonian system is as follows: in, H(x1,x2) is the storage function of the Hamiltonian system.

5. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 4, characterized in that:

6. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 3, characterized in that: The formula for calculating the input voltage observer is as follows: in, This represents the input voltage observer state, where β is the input voltage observer gain. This is the real-time data value of the input voltage observation. Input voltage observer state The first derivative with respect to time, x1 is the inductor current in the DC-DC buck converter, x2 is the output voltage in the DC-DC buck converter, d is the duty cycle of the switching control signal of the DC-DC buck converter, and L is the nominal value of the inductor of the DC-DC buck converter.

7. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 6, characterized in that: Step 3, the specific steps are as follows: Step 3.1: Convert the port Hamiltonian system into a closed-loop Hamiltonian system; Step 3.2: Construct the desired closed-loop Hamiltonian system; Step 3.3: Based on the closed-loop Hamiltonian system and the desired closed-loop Hamiltonian system, construct the passive controller for the Hamiltonian system; The calculation formula for the closed-loop Hamiltonian system is as follows: in, u is the input to the closed-loop Hamiltonian system, and H1(x1,x2) is the storage function of the closed-loop Hamiltonian system. The desired output voltage; The desired closed-loop Hamiltonian system is calculated using the following formula: Where x is the state vector, x = [x1, x2, x3] c ] T x c This represents the passive controller state, where α is the interconnect gain and r is the damping gain. Let x1 be the first derivative with respect to time. Let x1 be the first derivative with respect to time. For x c The first derivative with respect to time, H d (x) is the storage function of the desired closed-loop Hamiltonian system. The passive controller of the Hamiltonian system is calculated using the following formula: in, For passive controller state x c The first derivative with respect to time.

8. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 7, characterized in that: in, k is the passive controller gain.

9. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 7, characterized in that: Step 4, specifically, is as follows: Step 4.1: Calculate the real-time data value of the input voltage observation based on the input voltage observer. Step 4.2: Apply the formula Substituting the passive controller of the Hamiltonian system into the equation, we obtain the passive control law d, calculated as follows: Step 4.3: Transfer the real-time voltage observation data values As the input voltage term of the passive control law, the adaptive passive control law is obtained. The calculation formula is as follows:

10. The adaptive passive control method for a DC-DC buck converter with a ZIP load according to claim 9, characterized in that: when At that time, adaptive passive control law This makes the closed-loop system of the DC-DC buck converter with ZIP load asymptotically stable.

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