阅读说明：本技术 交错并联dc-dc变换器的切换控制方法、控制器及系统 (Switching control method, controller and system for interleaved parallel DC-DC converter ) 是由 潘磊磊 田崇翼 张桂青 王延伟 李咏 刘晓倩 于 2019-09-20 设计创作，主要内容包括：本公开提供了一种交错并联DC-DC变换器的切换控制方法、控制器及系统。其中,交错并联DC-DC变换器的切换控制方法包括：根据交错并联DC-DC变换器的所有工作状态及基尔霍夫定律,得到交错并联DC-DC变换器的离散时间模型,即切换模型,进而计算出下一时刻的交错并联DC-DC变换器的所有相电感电流预测值；根据交错并联DC-DC变换器的切换模型及外环电压控制,预测出下一时刻电感电流参考值；以交错并联DC-DC变换器的所有相电感电流均衡为目标,将下一时刻的所有相的电感电流预测值分别与下一时刻电感电流参考值比较,得到下一时刻的所有开关状态组合；筛选出最接近相应电感电流参考值对应的开关状态组合并作用到下一个开关时刻,得到最优切换率来控制交错并联DC-DC变换器工作。(The disclosure provides a switching control method, a controller and a system of interleaved parallel DC-DC converters. The switching control method of the interleaved parallel DC-DC converter comprises the following steps: obtaining a discrete time model, namely a switching model, of the interleaved parallel DC-DC converter according to all working states of the interleaved parallel DC-DC converter and kirchhoff's law, and further calculating all phase inductance current predicted values of the interleaved parallel DC-DC converter at the next moment; predicting a current reference value of the inductor at the next moment according to a switching model of the interleaved parallel DC-DC converter and outer loop voltage control; aiming at balancing all phase inductive currents of the interleaved parallel DC-DC converters, respectively comparing the inductive current predicted values of all phases at the next moment with the inductive current reference values at the next moment to obtain all switch state combinations at the next moment; and screening out the switching state combination corresponding to the most approximate corresponding inductive current reference value and applying the switching state combination to the next switching moment to obtain the optimal switching rate to control the interleaved parallel DC-DC converter to work.)

1. A switching control method of an interleaved parallel DC-DC converter, comprising:

obtaining a discrete time model, namely a switching model, of the interleaved parallel DC-DC converter according to all working states of the interleaved parallel DC-DC converter and kirchhoff's law, and further calculating the predicted value of the inductive current of all phases of the interleaved parallel DC-DC converter at the next moment;

predicting a current reference value of the inductor at the next moment according to a switching model of the interleaved parallel DC-DC converter and outer loop voltage control;

aiming at balancing all phase inductive currents of the interleaved parallel DC-DC converters, respectively comparing the inductive current predicted values of all phases at the next moment with the inductive current reference values at the next moment to obtain all switch state combinations at the next moment;

and screening out the switching state combination corresponding to the most approximate corresponding inductive current reference value and applying the switching state combination to the next switching moment to obtain the optimal switching rate to control the interleaved parallel DC-DC converter to work.

2. The switching control method of the interleaved parallel DC-DC converter according to claim 1, wherein an outer loop voltage control of the interleaved parallel DC-DC converter employs a PI controller.

3. The switching control method of the interleaved parallel DC-DC converter according to claim 2, wherein the PI controller is used to control the outer loop voltage of the interleaved parallel DC-DC converter, and the reference value of the inductor current at the next time is predicted to be:

I^*＝k_p(U₀-U_dc)+k_i∫(U₀-U_dc)dt

wherein, I^*To predict the next moment of timeA current sense reference value; k is a radical of_pProportional coefficient of PI controller; k is a radical of_iIs the integral coefficient of the PI controller; u shape₀The preset output voltage is the preset output voltage of the interleaved parallel DC-DC converter; u shape_dcIs the actual output voltage of the interleaved parallel DC-DC converters.

4. A switching controller for an interleaved parallel DC-DC converter, comprising:

the inductive current prediction module is used for obtaining a discrete time model, namely a switching model, of the interleaved parallel DC-DC converter according to all working states of the interleaved parallel DC-DC converter and kirchhoff's law, and further calculating the inductive current prediction value of all phases of the interleaved parallel DC-DC converter at the next moment;

the inductor current reference value calculating module is used for predicting an inductor current reference value at the next moment according to the switching model of the interleaved parallel DC-DC converter and the outer ring voltage control;

the switching state combination acquisition module is used for respectively comparing the inductance current predicted values of all phases at the next moment with the inductance current reference value at the next moment by taking the balance of all phase inductance currents of the staggered parallel DC-DC converters as a target to obtain all switching state combinations at the next moment;

and the optimal switching rate screening module is used for screening the switching state combination closest to the corresponding inductive current reference value and applying the switching state combination to the next switching moment to obtain the optimal switching rate to control the interleaved parallel DC-DC converter to work.

5. The switching controller of an interleaved parallel DC-DC converter as claimed in claim 4, wherein in said inductor current reference value calculating module, an outer loop voltage control of the interleaved parallel DC-DC converter employs a PI controller.

6. The switching controller of an interleaved parallel DC-DC converter according to claim 5, wherein in the inductor current reference value calculating module, a PI controller is used to control the outer loop voltage of the interleaved parallel DC-DC converter, and the inductor current reference value at the next time is predicted to be:

I^*＝k_p(U₀-U_dc)+k_i∫(U₀-U_dc)dt

wherein, I^*Predicting the reference value of the inductor current at the next moment; k is a radical of_pProportional coefficient of PI controller; k is a radical of_iIs the integral coefficient of the PI controller; u shape₀The preset output voltage is the preset output voltage of the interleaved parallel DC-DC converter; u shape_dcIs the actual output voltage of the interleaved parallel DC-DC converters.

7. A switching control system of an interleaved parallel DC-DC converter, characterized by comprising the switching controller of an interleaved parallel DC-DC converter according to any one of claims 4 to 6.

8. The switching control system of interleaved parallel DC-DC converters as claimed in claim 7 wherein the interleaved parallel DC-DC converters are interleaved parallel two level DC-DC converters or interleaved parallel three level DC-DC converters.

Technical Field

The disclosure belongs to the field of power electronic control, and particularly relates to a switching control method, a controller and a system for interleaved parallel DC-DC converters.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

The DC-DC converter is suitable for occasions of high-voltage conversion, such as photovoltaic power generation systems, uninterruptible power supplies, distributed power generation and the like. The existing DC-DC converter comprises a two-level converter and a three-level converter, the current of a switching tube is reduced to a half by the interleaving parallel technology, and output voltage and current ripples are reduced. Although the existing two-level bidirectional DC-DC converter has a simple structure, the filter has a large volume and the voltage stress of a switching tube is large. The three-level bidirectional DC-DC converter circuit topology greatly reduces the volume and weight of a filter, improves the dynamic response capability of the converter, reduces the voltage stress of a switching tube to be half of the high-end voltage, greatly reduces the switching frequency, and enables the current flowing through the switching tube to be half of the total current by the staggered parallel technology. The staggered three-level Boost converter achieves the advantages of small input and output current ripple, small output voltage ripple, low voltage stress of a switching tube, large output voltage range, three-level output and the like by using a proper inductance value.

There are currently a number of methods for controlling the converter, including PI control, fuzzy control, synovial control, etc. The PI control method has the advantages of simple algorithm, good control effect and the like, but the parameter design and selection process of the PI controller is complicated, and the small signal model based on the state space averaging method is obtained approximately by neglecting high-order terms in the model.

Disclosure of Invention

In order to solve the above problems, the present disclosure provides a switching control method, a controller, and a system for an interleaved parallel DC-DC converter, which enable an output voltage to accurately track a given value, greatly reduce overshoot of a DC bus voltage, and better achieve stabilization of the DC bus voltage, so that an inductive current ripple is greatly reduced, and a dynamic response performance is greatly improved.

In order to achieve the purpose, the following technical scheme is adopted in the disclosure:

a first aspect of the present disclosure provides a switching control method of an interleaved parallel DC-DC converter.

A switching control method of an interleaved parallel DC-DC converter includes:

obtaining a discrete time model, namely a switching model, of the interleaved parallel DC-DC converter according to all working states of the interleaved parallel DC-DC converter and kirchhoff's law, and further calculating the predicted value of the inductive current of all phases of the interleaved parallel DC-DC converter at the next moment;

predicting a current reference value of the inductor at the next moment according to a switching model of the interleaved parallel DC-DC converter and outer loop voltage control;

aiming at balancing all phase inductive currents of the interleaved parallel DC-DC converters, respectively comparing the inductive current predicted values of all phases at the next moment with the inductive current reference values at the next moment to obtain all switch state combinations at the next moment;

and screening out the switching state combination corresponding to the most approximate corresponding inductive current reference value and applying the switching state combination to the next switching moment to obtain the optimal switching rate to control the interleaved parallel DC-DC converter to work.

In one embodiment, the outer loop voltage control of the interleaved parallel DC-DC converter adopts a PI controller.

As an embodiment, a PI controller is adopted to control the outer ring voltage of the interleaved parallel DC-DC converter, and the reference value of the inductor current at the next moment is predicted to be:

I^*＝k_p(U₀-U_dc)+k_i∫(U₀-U_dc)dt

wherein, I^*Predicting the reference value of the inductor current at the next moment; k is a radical of_pProportional coefficient of PI controller; k is a radical of_iIs a PI controllerThe integral coefficient of (a); u shape₀The preset output voltage is the preset output voltage of the interleaved parallel DC-DC converter; u shape_dcIs the actual output voltage of the interleaved parallel DC-DC converters.

A second aspect of the present disclosure provides a switching controller of an interleaved parallel DC-DC converter.

A switching controller of an interleaved parallel DC-DC converter, comprising:

the inductive current prediction module is used for obtaining a discrete time model, namely a switching model, of the interleaved parallel DC-DC converter according to all working states of the interleaved parallel DC-DC converter and kirchhoff's law, and further calculating the inductive current prediction value of all phases of the interleaved parallel DC-DC converter at the next moment;

the inductor current reference value calculating module is used for predicting an inductor current reference value at the next moment according to the switching model of the interleaved parallel DC-DC converter and the outer ring voltage control;

the switching state combination acquisition module is used for respectively comparing the inductance current predicted values of all phases at the next moment with the inductance current reference value at the next moment by taking the balance of all phase inductance currents of the staggered parallel DC-DC converters as a target to obtain all switching state combinations at the next moment;

and the optimal switching rate screening module is used for screening the switching state combination closest to the corresponding inductive current reference value and applying the switching state combination to the next switching moment to obtain the optimal switching rate to control the interleaved parallel DC-DC converter to work.

In one embodiment, in the inductor current reference value calculation module, a PI controller is used for outer loop voltage control of the interleaved parallel DC-DC converter.

As an embodiment, in the inductor current reference value calculating module, a PI controller is used to control the outer loop voltage of the interleaved parallel DC-DC converter, and the inductor current reference value at the next time is predicted to be:

I^*＝k_p(U₀-U_dc)+k_i∫(U₀-U_dc)dt

wherein, I^*To prepareMeasuring the reference value of the inductor current at the next moment; k is a radical of_pProportional coefficient of PI controller; k is a radical of_iIs the integral coefficient of the PI controller; u shape₀The preset output voltage is the preset output voltage of the interleaved parallel DC-DC converter; u shape_dcIs the actual output voltage of the interleaved parallel DC-DC converters.

A third aspect of the present disclosure provides a switching control system of an interleaved parallel DC-DC converter.

A switching control system of an interleaved parallel DC-DC converter comprises the switching controller of the interleaved parallel DC-DC converter.

In one embodiment, the interleaved parallel DC-DC converter is an interleaved parallel two-level DC-DC converter or an interleaved parallel three-level DC-DC converter.

The beneficial effects of this disclosure are:

the switching control disclosed by the invention has the advantages of simple control idea, good control effect, high robustness, capability of realizing simultaneous control of a plurality of targets and the like; the switching control is optimized and controlled based on a converter model, the modeling is visual, the control is direct, the dynamic response is fast, complex PI parameters do not need to be adjusted, the problem of constraint optimal tracking control of a multivariable system is well solved, and compared with the traditional double closed-loop control, the switching control aims at a non-isolated staggered parallel two-level DC-DC converter and a staggered parallel three-level converter, the output voltage can accurately track a given value, the voltage overshoot of a direct-current bus is greatly reduced, the inductive current ripple is greatly reduced, and the dynamic response performance is greatly improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.

FIG. 1 is a topology diagram of an interleaved parallel two-level DC-DC converter of an embodiment of the present disclosure;

FIG. 2 is a topology diagram of an interleaved parallel three-level DC-DC converter of an embodiment of the present disclosure;

FIG. 3 is a flow chart of the switching control of the interleaved parallel DC-DC converters of an embodiment of the present disclosure;

fig. 4(a) is an equivalent circuit diagram of an operation mode 1 of an interleaved parallel two-level DC-DC converter according to an embodiment of the present disclosure;

fig. 4(b) is an equivalent circuit diagram of an operation mode 2 of an interleaved parallel two-level DC-DC converter according to an embodiment of the disclosure;

fig. 4(c) is an equivalent circuit diagram of an operation mode 3 of an interleaved parallel two-level DC-DC converter according to an embodiment of the disclosure;

fig. 4(d) is an equivalent circuit diagram of an operation mode 4 of an interleaved parallel two-level DC-DC converter according to an embodiment of the disclosure;

fig. 5(a) is an equivalent circuit diagram of an operation mode 1 of an interleaved parallel three-level DC-DC converter according to an embodiment of the present disclosure;

fig. 5(b) is an equivalent circuit diagram of an operation mode 2 of an interleaved parallel three-level DC-DC converter according to an embodiment of the present disclosure;

fig. 5(c) is an equivalent circuit diagram of an operation mode 3 of an interleaved parallel three-level DC-DC converter according to an embodiment of the present disclosure;

fig. 5(d) is an equivalent circuit diagram of an operation mode 4 of an interleaved parallel three-level DC-DC converter according to an embodiment of the disclosure;

fig. 6(a) is a simulated waveform diagram of output voltage when the interleaved parallel two-level DC-DC converter of the embodiment of the present disclosure is switched;

fig. 6(b) is a simulation waveform diagram of output current when the interleaved parallel two-level DC-DC converter of the embodiment of the present disclosure is switched;

fig. 7(a) is a simulated waveform diagram of output voltage when the interleaved parallel three-level DC-DC converter switches load according to the embodiment of the disclosure;

fig. 7(b) is a simulation waveform diagram of output current when the interleaved parallel three-level DC-DC converter switches the load according to the embodiment of the disclosure.

Detailed Description

The present disclosure is further described with reference to the following drawings and examples.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.