阅读说明：本技术 基于干扰观测器与积分滑模控制的boost变换器控制方法 (Boost converter control method based on disturbance observer and integral sliding mode control ) 是由 刘然 任幼逢 张白林 郭晓静 朱莉莉 张小涛 陈祺 平静洋 孙朋辉 燕少鹏 陈晓 于 2020-10-30 设计创作，主要内容包括：本发明涉及电力电子变换器领域,尤其涉及基于干扰观测器与积分滑模控制的boost变换器控制方法,包括：建立boost变换器的状态空间模型方程；基于状态空间模型方程并根据扰动观测器估计的不确定性建立积分滑模控制器；在线路输入电压和/或负载电阻不确定时,通过积分滑模控制器调节输出电压。通过使用本发明,可以实现以下效果：1、直接输出电压控制；2、无需任何附加硬件就可保证恒定的开关频率；3、无需测量输入电压；4、对线路、负载不确定性具有很强的鲁棒性,能够跟踪参考电压。(The invention relates to the field of power electronic converters, in particular to a boost converter control method based on disturbance observer and integral sliding mode control, which comprises the following steps: establishing a state space model equation of the boost converter; establishing an integral sliding mode controller based on a state space model equation and according to uncertainty estimated by a disturbance observer; when the line input voltage and/or the load resistance are uncertain, the output voltage is regulated through the integral sliding mode controller. By using the present invention, the following effects can be achieved: 1. direct output voltage control; 2. constant switching frequency can be guaranteed without any additional hardware; 3. the input voltage does not need to be measured; 4. the method has strong robustness to line and load uncertainty, and can track the reference voltage.)

1. The boost converter control method based on the disturbance observer and integral sliding mode control is characterized by comprising the following steps of:

establishing a state space model equation of the boost converter;

establishing an integral sliding mode controller based on a state space model equation and according to uncertainty estimated by a disturbance observer;

when the line input voltage and/or the load resistance are uncertain, the output voltage is regulated through the integral sliding mode controller.

2. The boost converter control method based on disturbance observer and integral sliding mode control according to claim 1, wherein the state space model equation of the boost converter is as follows:

wherein i_LRepresents the current through the inductor; v. of_CRepresenting the voltage across the capacitor, L representing the inductance; c represents capacitance; u represents the input voltage; r represents a load resistance; v. of_gRepresenting the line input voltage.

3. The boost converter control method based on disturbance observer and integral sliding mode control according to claim 2, characterized in that the nonlinear mathematical model is simplified to obtain:

wherein, a'₁₁、a′₂₁K is a known constant, and a₁₂、a₂₂Is an uncertain variable; state variable x₁And x₂Is defined as the control target is such that x₂Becomes zero;represents a state variable x₁A derivative of (a);representation represents a state variable x₂A derivative of (a); d₁And d₂Indicating an uncertainty.

4. The boost converter control method based on disturbance observer and integral sliding mode control according to claim 3, wherein the establishing of the integral sliding mode controller based on the state space model equation and according to the uncertainty estimated by the disturbance observer comprises:

establishing an integral sliding mode surface for compensating for mismatched perturbations:

wherein, c₁，c₂And alpha is a normal number selected by the user; sigma^*Can ensure that sigma is equal to 0 when t is equal to 0^*＝0；

The sliding surface dynamics formula obtained by differentiating the integral sliding mode surface and using the simplified nonlinear mathematical model is as follows:

designing a control rule u to satisfy the sliding conditionThe integral sliding mode controller is obtained as follows:

Technical Field

The invention relates to the field of power electronic converters, in particular to a boost converter control method based on disturbance observer and integral sliding mode control.

Background

The DC-DC converter is widely applied to photovoltaic power generation, a fuel cell system, a wind power generation system, a telecommunication system, a direct current micro-grid and power factor correction, and the boost converter is a common converter in the DC-DC converter and has the advantages that: the topological structure is simple, the required elements are few, and the working reliability is high. In boost converter voltage regulation applications, the converter is required to maintain a constant output voltage when there is uncertainty in the line and load. The control objective is to regulate the output voltage under indeterminate conditions so that it has good transient performance and is easy to implement.

The boost converter has been difficult to control because it is a bilinear, non-minimally mismatched system. The sliding mode control of the traditional boost converter adopts an indirect control method to adjust the inductive current instead of the output voltage, but the indirect control scheme can cause unexpected complexity of signal calculation.

Disclosure of Invention

In order to solve the problems, the invention provides a boost converter control method based on a disturbance observer and integral sliding mode control, uncertainty estimation of input voltage and load resistance is carried out through the disturbance observer, and the estimated value is applied to a control rule of the integral sliding mode control, so that the purpose of adjusting output voltage when line input voltage and load resistance are uncertain is achieved.

The boost converter control method based on the disturbance observer and integral sliding mode control comprises the following steps:

establishing a state space model equation of the boost converter;

establishing an integral sliding mode controller based on a state space model equation and according to uncertainty estimated by a disturbance observer;

when the line input voltage and/or the load resistance are uncertain, the output voltage is regulated through the integral sliding mode controller.

Preferably, the state space model equation of the boost converter is as follows:

wherein i_LRepresents the current through the inductor; v. of_CRepresenting the voltage across the capacitor, L representing the inductance; c represents capacitance; u represents the input voltage; r represents a load resistance; v. of_gRepresenting the line input voltage.

Preferably, the nonlinear mathematical model is simplified to obtain:

wherein, a₁′₁、a₂′₁K is a known constant, and a₁₂、a₂₂Is an uncertain variable; state variable x₁And x₂Is a quiltDefined as the control objective is to have x₂Becomes zero;represents a state variable x₁A derivative of (a);representation represents a state variable x₂A derivative of (a); d₁And d₂Indicating uncertainty

Preferably, the establishing of the integral sliding-mode controller based on the state space model equation and according to the uncertainty estimated by the disturbance observer includes:

establishing an integral sliding mode surface for compensating for mismatched perturbations:

wherein, c₁，c₂And alpha is a normal number selected by the user; sigma^*Can ensure that sigma is equal to 0 when t is equal to 0^*＝0；

The sliding surface dynamics formula obtained by differentiating the integral sliding mode surface and using the simplified nonlinear mathematical model is as follows:

designing a control rule u to satisfy the sliding conditionThe integral sliding mode controller is obtained as follows:

the invention estimates the uncertainty of the line and the load by using the disturbance observer, and then applies the uncertainty to the integral sliding mode control law, thereby realizing the purpose of regulating the output voltage under the condition that the input voltage and the load are uncertain. The ability of the controller to track the reference voltage and regulate the output voltage is analyzed, which has the following advantages: 1. direct output voltage control; 2. constant switching frequency can be guaranteed without any additional hardware; 3. the input voltage does not need to be measured; 4. the method has strong robustness to line and load uncertainty, and can track the reference voltage.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a circuit diagram of the topology of a boost converter in an embodiment of the invention;

FIG. 2 is a schematic flow chart of a boost converter control method based on disturbance observer and integral sliding mode control according to an embodiment of the invention;

FIG. 3 shows a line input voltage v according to an embodiment of the present invention_gThe curve diagram of the output voltage and the load current under the uncertain condition;

FIG. 4a shows a line input voltage v according to an embodiment of the present invention_gInput voltage v under indeterminate conditions_gOutput voltage V equal to 20V_OAnd inductor current i_LA schematic diagram of a curve of (a);

FIG. 4b shows the line input voltage v according to an embodiment of the present invention_gInput voltage v under indeterminate conditions_gOutput voltage V equal to 24V_OAnd inductor current i_LA schematic diagram of a curve of (a);

FIG. 4c shows the line input voltage v according to an embodiment of the present invention_gInput voltage v under indeterminate conditions_gOutput voltage V equal to 28V_OAnd inductor current i_LA schematic diagram of a curve of (a);

fig. 5 is a graph illustrating the output voltage and the load current when the load resistance is uncertain according to an embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

The topology utilized by the embodiment of the present invention is a boost converter, as shown in fig. 1, wherein the main devices are: the device comprises a direct-current voltage source V, a switching tube Q, a diode D, an inductor L, a capacitor C and a load R.

Based on the above boost converter, an embodiment of the present invention provides a boost converter control method based on a disturbance observer and integral sliding mode control, as shown in fig. 1, including the following steps:

s1: establishing a state space model equation of the boost converter;

s2: establishing an integral sliding mode controller based on a state space model equation and according to uncertainty estimated by a disturbance observer;

s3: when the line input voltage and/or the load resistance are uncertain, the output voltage is regulated through the integral sliding mode controller.

Integral sliding mode control is an improvement over sliding mode control, which can reduce the uncertainty of the system. In addition, the disturbance observer designed by utilizing integral sliding mode control can realize continuous control, eliminate buffeting and simultaneously ensure strong robustness and high precision of sliding mode control. The integral sliding mode control method designed based on the disturbance observer can adjust the output voltage when the input voltage and the load are uncertain, can track the reference voltage and ensure constant switching frequency.

Establishing a state space model equation of the boost converter, it is noted that the boost converter can operate in a current continuous operation mode (CCM) or a current discontinuous operation mode (DCM). The load resistance selected in the present invention satisfies the Current Continuous Mode (CCM) condition. Thus, the converter will always operate in a current continuous mode of operation (CCM). The state space model equation of the converter in the current continuous working mode (CCM) is specifically as follows:

wherein i_LRepresents the current through the inductor; v. of_CRepresenting the voltage across the capacitor, L representing the inductance; c represents capacitance; u represents the input voltage; r represents a load resistance; v. of_gIndicating line input powerAnd (6) pressing. In the following, the output voltage is v_OIs represented by v_OIs equal to v_C. It can be noted that the load resistance R and the input voltage v_gUnknown, but whose values lie within known ranges. Expressed as follows using a matrix equation:

the parasitic elements of the converter are not included in the state space model equation (1). The control objective is to regulate the output voltage with both uncertainty in the input voltage and load resistance and to track the reference voltage.

Preferably, the state space model equation can be simply rewritten as:

wherein the content of the first and second substances,

x₁＝i_L,x₂＝v_C-V_ref (4)

d₁＝-a₁′₁(V_ref+ku-V_refu)+a₁₂ (6)

d₂＝-a′₂₁ux₁-a₂₂(x₂+V_ref) (7)

wherein a'₁₁、a′₂₁K are known constants, and a₁₂、a₂₂Is an uncertain variable. The rewritten mathematical model (3) is simpler than the original model. State variable x₁And x₂Is defined as the control target is such that x₂Becomes zero. V_refRepresents;represents a state variable x₁A derivative of (a);representation represents a state variable x₂A derivative of (a); d₁And d₂Indicating an uncertainty. When the integral sliding mode controller based on the disturbance observer is established, the proposed control rule can be proved to enable x to be₂Asymptotically to zero.

And establishing an integral sliding mode controller based on a state space model equation and according to the uncertainty estimated by the disturbance observer. The disturbance observer estimates the uncertainty of the line input voltage and the load resistance, which is then applied to the control law.

Uncertainty d₁The disturbance observer of (2) is designed as follows:

in the formula, l₁>0 is observer gain, p₁Is the auxiliary variable which is the variable of the auxiliary variable,is d₁An estimated value of, and representing an auxiliary variable p₁A derivative of (a);represents the uncertainty d₁The error of (2). Subtracting from both sides of equation (9)Obtaining:

represents the uncertainty d₁A derivative of (a);represents the uncertainty d₁The derivative of the error of (a).

Likewise, uncertainty d₂Estimated as:

in the formula, l₂>0 is observer gain, p₂Is the auxiliary variable which is the variable of the auxiliary variable,is d₂An estimated value of, andsubtracting from both sides of equation (14)Obtaining:

as can be seen from the formulas (11) and (15), if d₁And d₂Is constant, the estimation error will asymptotically approach zero. If d is₁And d₂Is a slowly varying parameter, the estimation error will remain within a small range of zero. In a boost converter, the load resistance and the input voltage change in a step-wise manner at the moment of isolation, otherwise they would be unknown constants. Therefore, in these cases, the first and second sensors,andis 0 and is therefore at l₁>0 and l₂>The stability of the estimation error can be guaranteed when the value is 0.

Establishing an integral sliding mode surface for compensating for mismatched perturbations:

wherein, c₁，c₂And α is a user-selected normal number. Sigma^*Can ensure that sigma is equal to 0 when t is equal to 0^*0. By differentiating the integral sliding mode surface and using a simplified nonlinear mathematical model, the kinetic formula of the sliding surface can be obtained as follows:

designing a control rule u to satisfy the sliding conditionThe integral sliding mode controller is obtained as follows:

in the above formula, k_lIs a normal parameter selected by a user and is used for ensuring the sliding mode control conditionBoth in the case where t and k are positive numbers. This control is chosen for any v_CThe value is neither passive nor infinite. c. C₁、c₂The value of (A) ensures x₂The value of (d) approaches 0. It is also indicated in the integral sliding mode controller that it is not affected by the sign and sign function. The integral sliding mode controller ensures constant switching frequency, does not need any additional hardware circuit, and has no jitter in output voltage. In addition, the integrating sliding mode controller does not need to measure any input voltage v_g. (6) The line and load uncertainties that occur in equations (7) and (7) are resolved by the estimates in equation (18), and the gain l of the observer can be seen by equations (11) and (15)₁And l₂Is determined. Control u will result in slip form surface σ^*Remains 0 for any time t when σ^*When equal to 0, x₂The kinetic formula of (a) is as follows:

this shows that ifIs a constant number, x₂Will asymptotically approach 0. It can also be seen that by choosing the appropriate c₁、c₂The value can control the error x₂The instantaneous state of (c).

Slip form surface sigma^*Stability analysis of (3). Consider first the Lyapunov function:

σ^*by substituting (18) into (17):

for V (sigma)^*) The differential is obtained by using the following formula (21):

the equation (22) can be used to derive | σ^*Ultimately, will be determined by:

increasing k_lCan reduce sigma^*Upper limit of (2), but increasing k_lDoes not increase the size of u in (18) because σ^*Always close to 0, since the uncertainty is a step change and then becomes constant. It can thus be concluded that except for the moment of step change, σ^*Will be close to zero.

In an example embodiment, the input voltage v_g24V, 200 μ H inductance L, 330 μ F output capacitance C, 100 Ω load resistance R, and reference voltage V_ref＝48V；c₁＝12×10³、c₂＝8×10⁵、k＝50、k_l＝10³、l₁＝9×10²、l₂＝9×10²、α＝2×10³。

At line input voltage v_gIn the case of uncertainty, the line input voltage v_gThe experiment was repeated using the method of the present invention after stepwise changes in the order of 20-24-28V. The output voltage and load current are shown in fig. 3. It can be seen that the output voltage remains at 48V. In transient behavior, v_gRespectively 1.32V and 1.26V, and a duration of 36ms and 34ms, respectively, fig. 4a, 4b and 4c show the input voltage V, respectively_gOutput voltage V equal to 20V, 24V and 28V_OAnd inductor current i_LCurve (c) of (d). It can be seen that the frequency of the inductor current is constant at 100KHz as the input voltage is increased from 20V to 28V.

Under the condition of uncertain load resistance, inputting the voltage v_gAnd a reference voltage V_refRespectively, at 24V and 48V, while the load resistance R is changed stepwise in a manner of 100-50-25 omega. Shown in fig. 5 is a graph of output voltage and load current. The transient changes in the load resistance R are 0.34V and 0.44V, respectively, and the durations are 21ms and 24ms, respectively. It is also clear that the control method proposed by the present invention does not show a stability error.

The invention estimates the uncertainty of the line and the load by using the disturbance observer, and then applies the uncertainty to the integral sliding mode control law, thereby realizing the purpose of regulating the output voltage under the condition that the input voltage and the load are uncertain. The ability of the controller to track the reference voltage and regulate the output voltage is analyzed, which has the following advantages: 1. direct output voltage control; 2. constant switching frequency can be guaranteed without any additional hardware; 3. the input voltage does not need to be measured; 4. the method has strong robustness to line and load uncertainty, and can track the reference voltage.

Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.