高性能直流變換器系統(tǒng)穩(wěn)定性問(wèn)題研究
發(fā)布時(shí)間：2018-09-13 08:56
【摘要】：摘要：隨著電源、負(fù)載特性需求的不同,越來(lái)越多的DC-DC變換器采用高階化拓?fù)浠蛘卟捎梅植际郊?jí)聯(lián)方式相互連接形成高性能的直流變換器系統(tǒng),以滿足不同的設(shè)計(jì)要求。直流變換器系統(tǒng)的穩(wěn)定性一直以來(lái)是人們研究的熱點(diǎn)。變換器的小信號(hào)模型參數(shù)是影響變換器系統(tǒng)穩(wěn)定性的重要因素,本文針對(duì)影響變換器系統(tǒng)穩(wěn)定性的關(guān)鍵參數(shù)：被控對(duì)象模型傳遞函數(shù)、音頻敏感率、輸入阻抗以及輸出阻抗進(jìn)行分析,并提出相應(yīng)的優(yōu)化方法以改善變換器系統(tǒng)的穩(wěn)定性。 目前已有大量文獻(xiàn)對(duì)基本的二階變換器拓?fù)溥M(jìn)行了深入分析,已解決了穩(wěn)定性問(wèn)題,但是在包含太陽(yáng)能電池板、蓄電池等裝置的場(chǎng)合,為了滿足輸入輸出電流連續(xù)的要求,往往需要加入額外的濾波器或者采用含有多個(gè)電感電容元件的高階變換器。高階變換器的模型中含有多個(gè)零極點(diǎn),尤其當(dāng)模型中存在右半平面零點(diǎn)時(shí),被控對(duì)象傳遞函數(shù)的相頻曲線容易較早穿越.180。,限制反饋環(huán)路增益的帶寬。本文歸納了優(yōu)化高階變換器被控對(duì)象的阻尼設(shè)計(jì)方法,針對(duì)廣泛應(yīng)用于航天電源系統(tǒng)的Superbuck變換器拓?fù)?提出一種RC阻尼設(shè)計(jì)方法,從而避免其被控對(duì)象傳遞函數(shù)中存在右半平面零點(diǎn),保證其模型滿足最小相位系統(tǒng)的條件,從而提高變換器的穩(wěn)定性。 采用輸入電壓前饋的方法可以在理論上實(shí)現(xiàn)變換器的音頻敏感率(輸入電壓擾動(dòng).輸出電壓擾動(dòng)傳遞函數(shù),audio susceptibility)等于零。但是當(dāng)變換器模型的階次較高時(shí),理論所需的前饋控制器傳遞函數(shù)較為復(fù)雜且計(jì)算過(guò)程繁瑣。為了簡(jiǎn)化求解過(guò)程,本文提出一種簡(jiǎn)化變換器電路模型的方法,而不會(huì)影響所得前饋控制器的準(zhǔn)確性。此外,本文提出采用比例控制器代替理論所需的前饋控制器進(jìn)行控制的方法,并分析了在這種控制方式下音頻敏感率能夠大幅度衰減的有效頻率范圍與主電路參數(shù)之間的關(guān)系,指出了比例前饋控制器僅取決于變換器的穩(wěn)態(tài)電壓增益比的規(guī)律。 在級(jí)聯(lián)系統(tǒng)中,即使變換器單獨(dú)能夠穩(wěn)定工作,級(jí)聯(lián)時(shí)也未必穩(wěn)定,這是由于級(jí)聯(lián)的前后級(jí)變換器阻抗存在相互作用。為了提高級(jí)聯(lián)系統(tǒng)的穩(wěn)定性,需要減小前后級(jí)變換器的阻抗交截范圍,對(duì)于DC-DC變換器而言,一方面希望降低前級(jí)變換器的輸出阻抗,另一方面希望增大后級(jí)變換器的輸入阻抗。 本文基于DC.DC變換器的一般性小信號(hào)模型,提出了以平均輸入電流環(huán)為內(nèi)環(huán)、輸出電壓環(huán)為外環(huán)的雙環(huán)控制方法,分析了在這種控制方式下影響變換器輸入阻抗的因素,并給出了改變內(nèi)環(huán)電流采樣系數(shù)前后變換器輸入阻抗的量化計(jì)算過(guò)程。分析表明,當(dāng)電流內(nèi)環(huán)的截止頻率大于電壓外環(huán)截止頻率時(shí),增大電流采樣系數(shù),能夠提高電流內(nèi)環(huán)環(huán)路增益,有效增大變換器的輸入阻抗。從而在級(jí)聯(lián)系統(tǒng)中,能夠有效減小負(fù)載變換器的輸入阻抗與源變換器輸出阻抗的交集,提高級(jí)聯(lián)系統(tǒng)的穩(wěn)定性。 同樣的,為了優(yōu)化變換器的輸出阻抗,提出了一種在變換器輸出端口模擬出并聯(lián)虛擬電阻的控制方法,可以適用于模型中不含右半平面零點(diǎn)的變換器拓?fù)�。這種控制方法在不改變變換器穩(wěn)態(tài)工作點(diǎn)的基礎(chǔ)上僅改變了交流小信號(hào)模型,因此不會(huì)帶來(lái)額外的功率損耗。通過(guò)采用有源阻尼控制器的方法,可以有效降低變換器輸出阻抗的諧振峰值,改善品質(zhì)因數(shù),達(dá)到優(yōu)化變換器輸出阻抗特性的目的。
[Abstract]:Abstract: With the different demand of power supply and load characteristics, more and more DC-DC converters adopt high-order topology or adopt distributed cascade interconnection to form high-performance DC-DC converter systems to meet different design requirements. Small signal model parameters are important factors affecting the stability of the converter system. In this paper, the key parameters affecting the stability of the converter system are analyzed, including the controlled object model transfer function, audio sensitivity, input impedance and output impedance, and the corresponding optimization methods are proposed to improve the stability of the converter system.
At present, a large number of literatures have analyzed the basic second-order converter topology deeply, and solved the stability problem. But in the case of solar panels, batteries and other devices, in order to meet the continuous input and output current requirements, it is often necessary to add additional filters or adopt high inductance and capacitance components. First-order converter. The model of high-order converter contains multiple zeros and poles. Especially when there are right half-plane zeros in the model, the phase-frequency curve of the transfer function of the controlled object is easy to cross. 180., which limits the bandwidth of the feedback loop gain. A RC damping design method is proposed to avoid the existence of right half-plane zeros in the transfer function of the controlled object and ensure that the model satisfies the condition of the minimum phase system.
The audio susceptibility of the converter can be realized theoretically by using the input voltage feedforward method. However, when the order of the converter model is high, the transfer function of the theoretical feedforward controller is complex and the calculation process is complicated. This paper presents a method to simplify the circuit model of the converter without affecting the accuracy of the feed-forward controller. In addition, a proportional controller is proposed to replace the feed-forward controller required by the theory. The effective frequency at which the audio sensitivity can be greatly attenuated is also analyzed. The relationship between the rate range and the parameters of the main circuit indicates that the proportional feed-forward controller only depends on the steady-state voltage gain ratio of the converter.
In cascaded systems, even if the converter can work stably alone, the cascade is not necessarily stable. This is due to the interaction between the impedance of the cascaded front and back converters. On the other hand, it hopes to increase the input impedance of the post converter.
Based on the general small-signal model of DC.DC converter, a double-loop control method with average input current loop as inner loop and output voltage loop as outer loop is proposed in this paper. The analysis shows that when the cut-off frequency of the current inner loop is greater than that of the voltage outer loop, increasing the current sampling coefficient can improve the gain of the current inner loop and increase the input impedance of the converter effectively. Stability of cascaded systems.
Similarly, in order to optimize the output impedance of the converter, a control method is proposed to simulate the parallel virtual resistance at the output port of the converter, which can be applied to the converter topology without the right half-plane zeros in the model. This method can effectively reduce the resonant peak value of the output impedance of the converter, improve the quality factor and optimize the output impedance characteristics of the converter.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM46
本文編號(hào)：2240672
[Abstract]:Abstract: With the different demand of power supply and load characteristics, more and more DC-DC converters adopt high-order topology or adopt distributed cascade interconnection to form high-performance DC-DC converter systems to meet different design requirements. Small signal model parameters are important factors affecting the stability of the converter system. In this paper, the key parameters affecting the stability of the converter system are analyzed, including the controlled object model transfer function, audio sensitivity, input impedance and output impedance, and the corresponding optimization methods are proposed to improve the stability of the converter system.
At present, a large number of literatures have analyzed the basic second-order converter topology deeply, and solved the stability problem. But in the case of solar panels, batteries and other devices, in order to meet the continuous input and output current requirements, it is often necessary to add additional filters or adopt high inductance and capacitance components. First-order converter. The model of high-order converter contains multiple zeros and poles. Especially when there are right half-plane zeros in the model, the phase-frequency curve of the transfer function of the controlled object is easy to cross. 180., which limits the bandwidth of the feedback loop gain. A RC damping design method is proposed to avoid the existence of right half-plane zeros in the transfer function of the controlled object and ensure that the model satisfies the condition of the minimum phase system.
The audio susceptibility of the converter can be realized theoretically by using the input voltage feedforward method. However, when the order of the converter model is high, the transfer function of the theoretical feedforward controller is complex and the calculation process is complicated. This paper presents a method to simplify the circuit model of the converter without affecting the accuracy of the feed-forward controller. In addition, a proportional controller is proposed to replace the feed-forward controller required by the theory. The effective frequency at which the audio sensitivity can be greatly attenuated is also analyzed. The relationship between the rate range and the parameters of the main circuit indicates that the proportional feed-forward controller only depends on the steady-state voltage gain ratio of the converter.
In cascaded systems, even if the converter can work stably alone, the cascade is not necessarily stable. This is due to the interaction between the impedance of the cascaded front and back converters. On the other hand, it hopes to increase the input impedance of the post converter.
Based on the general small-signal model of DC.DC converter, a double-loop control method with average input current loop as inner loop and output voltage loop as outer loop is proposed in this paper. The analysis shows that when the cut-off frequency of the current inner loop is greater than that of the voltage outer loop, increasing the current sampling coefficient can improve the gain of the current inner loop and increase the input impedance of the converter effectively. Stability of cascaded systems.
Similarly, in order to optimize the output impedance of the converter, a control method is proposed to simulate the parallel virtual resistance at the output port of the converter, which can be applied to the converter topology without the right half-plane zeros in the model. This method can effectively reduce the resonant peak value of the output impedance of the converter, improve the quality factor and optimize the output impedance characteristics of the converter.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM46
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