070441.TW ^5265twf.doc/i 九、發明說明： 【發明所屬之技術領域】 且特別是有關於一 本發明是有關於一種電源轉換器 種具有紋波補償的電源轉換器。 【先前技術】 ，著電子科技的進步，許多電子產品已成了人們生活 :備的卫具。由於現代人生活講究高效率及高品質，現 7的電子產品往往必須將不同魏的⑼或敝架構在一 起’以達到多功能性的操作。這種多魏㈣電子產品必 /頁透過夕組的電源供應器(p〇wers_y)，來提供各項模組 :需求的操作電壓。然而，當電子產品使用過多電源供應 «κ»的同時，其生產成本與電路佈局面積也將相對地提升。 在早期的系統中，設計者使用電壓調整器（voltage regulator)以及電荷幫浦電路(charge pump ckcuit)來解決這 個問題。其中，由於電荷幫浦電路無法提供大驅動電流， 故現今的應用系統大多以電源轉換器(p〇wer c〇nverter)來 取代電荷幫浦電路。 電源轉換器是一種利用電感及電容高速充放電的電 源轉換電路’不但具有升壓轉換器（b〇〇st c〇nverter)的結 構’尚有降壓（buck)、反轉（inverting)以及變壓器返驰 (transformer flyback)等多種不同的架構。一般而言，電源 轉換裔多半是以電阻分壓的回授方式，來控制其所產生的 輸出電壓。但是，電源轉換器所產生的輸出電壓通常載有 07044 l.TW 25265twf.doc/n 紋波(ripple)。此紋波會使得回授的電壓產生誤差’進而降 低電源轉換器之輸出電壓的準確度。 為了降低電源轉換器之輸出電壓中的紋波’設計者大 多使用一種低等效串聯電阻(equivalent serial resistance， ESR)的電容，來儲存輸出電壓。然而，低等效串聯電阻的 電容卻會降低輸出電壓的阻尼因數，進而致使輸出電壓產 生不穩定的振盪。 【發明内容】 本發明提供一種具有紋波補償的電源轉換器，利用一 虛擬阻抗來增加輸出電壓的阻尼因數，並利用第二電容上 的電壓變化來達到紋波補償的功效。藉此，本發明之電源 轉換器將有效地提升輸出電壓的準破度。 本發明提供一種具有紋波補償的電源轉換器，包括電 壓轉換裝置、部分凱文電路、第二電阻以及第二電容。且 電壓轉換裝置包括濾波電路以及比較器。其中，電壓轉換 裝置用以將一輸入電壓轉換並穩壓成一輸出電壓。濾波電 路用以對一脈波訊號進行濾波，以獲得所述輸出電壓，其 中濾波電路包括一電感，且脈波訊號為導通或斷開輸入電 壓而得。此外，比較器用以比較參考電壓與回授電壓，以 致使電壓轉換裝置根據比較器的輸出而調整所述脈波訊 號，其中回授電壓與輪出電壓的比值為阻抗比。 再者，部分凱文電路由串接的第一電阻與第一電容所 構成，且部分凱文電路與上述的電感並聯。第二電阻與第 070441 .TW 25265twf.doc/n 一電容並聯，且第二電容的一端耦接至第二電阻，而其另 h輕接至比幸父盗的輸出。其中，部分訊文電路會與所述 電感形成一個完整的凱文電路，以致使電感的電流變化可 透過部分凱文電路反映在第二電阻上。 此外，第二電阻與第二電容會形成一交流通道，以致 使第一電容上的電壓變化可以回傳至比較器的輸出，進而 達到紋波補償的功效。另一方面，電源轉換器會形成一虛 擬阻抗來提高輸出電壓的阻尼因數，進而避免振盪現象的 發生其中’虛擬阻抗的大小取決於電感、第一電阻與第 二電阻的阻值。 本發明利用一虛擬阻抗來增加輸出電壓的阻尼因 ，，並利用第二電阻與第二電容所形成的交流通道，來補 偾輸出電壓的直流誤差。如此—來，與習知技術相較之下， 本發明將有效地提升輸出電壓的準確度。 為讓本發明之上述特徵和優點能更明顯易懂，下文特 牛較佳實關，麵合所㈣^，作詳細說明如下。 【實施方式】 、、/5絲H繪福依據本發明~實施例之具有紋波補償的電 廢心广的電路圖。請參照圖卜電源轉換器100包括電 ㈣置UG、部分飢文電路120'電阻R2以及電容^ 歸置包括濾波電路⑴、比較器112、㈣ 1 113、時脈產生器114、脈波寬度調變器μ、電限 R3與心、以及電晶體打與乃。 070441.TW 25265twf.doc/n 在電壓轉換裝置110中，電晶體T1的第—源/汲極用 ，接收輸入電壓Vin，而其第二源/汲極則用以產生脈波訊 號Spl。電晶體T2的第一源/汲極耦接至電晶體下丨的第二 源/汲極，且其第二源/汲極耦接至地端。脈波寬度調變器 Π5耦接至電晶體T1與T2的閘極，並用以控制電晶體们 與T2的導通狀態。時脈產生器114與比較器U2的輸出 則耦接至脈波寬度調變器115。 另一方面，電壓產生器113用以產生—參考電壓 Vref。電阻&的一端耦接至電壓轉換裝置11〇的輸出，且 其另一端用以產生一回授電壓Vfb。電阻尺4則耦接在電阻 R3的另一端與地端之間。藉此’比較器112將比較其兩端 所接收到的參考電壓Vref與回授電壓Vfb ’以致使電壓轉 換裝置110根據比較器112的輸出而調整脈波訊號Sy。再 ，，濾波電路in則是用以對脈波訊號Spi進行濾波15，以 件到-輸出電壓Vout。其中，回授電壓與輪出電壓乂⑽ 的比值為一阻抗比。 另外，濾波電路111包括有電感L、電阻心以及電容 C3。電感L的兩端分別耦接至電晶體T1的第二源/汲極與 電愿轉換裝置110的輸出。電阻r5的—端祕至電壓轉換 裝置11〇的輸出。電容a則是耦接在電阻&之另一端與 地端之間。其中，f阻115是為電容^的等效㈣電阻。 在整體作動上，當比較器112所接收的回授電壓Vref •I於參考電壓Vref時’則表示電壓轉換裝置的電壓轉 換輪出低於預定值。此時，脈波寬度調變器115會切換電 07044 l.TW 25265twf.d〇c/n 晶體T1與T2的導通狀態，以增加脈波訊號Spi的責任週 期(duty cycle)。之後，脈波訊號Spi會透過電感對電容 C3進行充放電，以產生輪出電壓说。 1。。相反的，在回授電壓Vref大於參考電壓圻#時，比 ke 112則會致使脈波寬度調變器115控制電晶體丁丨與 Ή ’進一步使電塵轉換裝置11〇降低脈波訊號&的責任 週期。值得-提的是，時脈產生器m用以產生一時脈信 號’且脈;皮寬度調變n lls是依據比較$ 112 _較結果 與電容C2_L的f壓變化來調整此雜信號，並仙調整後 的時脈信號來加以控制電晶體丁丨與72的導通狀態。 一為了致使熟悉此技術者能更瞭解本實施的技術内 各，以下將詳述電壓轉換裝置11〇與電容C2、電阻R2、部 分凱文電路120的作動原理。 δ月繼續參照圖1，電容C2的一端耦接至電阻R2，且 其另一端耦接至比較器112的輸出。電阻R2則與電容Ci 並聯。此外，部分訊文電路12〇由串接的電阻R】與電容 h所構成。在此，部分凱文電路12〇會藉由與電感l的相 互並馬卩來形成威文連接(Keivin connecti〇n)，並進而成為一 個完整的凱文電路。 由於電阻心與電容〇1是以凱文連接的方式來與電感 L相互耦接，因此，部分凱文電路12〇可以精準地量測到 電感L的電流變化。且此電流變化的情形，將以電壓的形 j被反映在電容C]上。另外，流經電阻r2的電流也將隨 著電谷C!兩端電壓的變化而產生變動，並進而造成電容 1337795 07044 l.TW 25265twf.doc/n C：2上的電壓變化。此外，電阻R2與電容C2會形成一交流 通道，以致使電容〇2上的電壓變化可以回傳至脈波寬度調 變器115。藉此，脈波寬度調變器115將依據比較器112 的比較結果與電容C2上的電壓變化，來調整電晶體T1與 T2的導通狀態，進而達到紋波補償的功效。 另一方面，濾波電路ιη所採用的電容心為一種具 有低等效串聯電阻的電容。換言之，電阻R5的阻值非常 的低。主要的原因在於，如式（1)所示的，輸出電壓v〇ut 的纹波大小與電容C3的等效串聯電阻R£SR成正比。070441.TW ^5265twf.doc/i IX. Description of the Invention: [Technical Field of the Invention] In particular, the present invention relates to a power converter having a ripple compensation for a power converter. [Prior Art] With the advancement of electronic technology, many electronic products have become the lifeguards of people's lives. Due to the high efficiency and high quality of modern people's life, the current electronic products often have to be constructed with different (9) or 敝 architectures to achieve versatility. This multi-wei (four) electronic product must be provided through the power supply (p〇wers_y) of the group to provide various modules: the required operating voltage. However, while electronic products use too much power supply «κ», their production costs and circuit layout area will also increase relatively. In earlier systems, designers used a voltage regulator and a charge pump ckcuit to solve this problem. Among them, since the charge pump circuit cannot provide a large driving current, most of today's application systems use a power converter (p〇wer c〇nverter) instead of a charge pump circuit. The power converter is a power conversion circuit that uses high-speed charging and discharging of inductors and capacitors. It has a structure of a boost converter (b〇〇st c〇nverter). There are also buck, inverting, and transformers. A variety of different architectures such as transformer flyback. In general, most of the power conversions are controlled by a resistor divider to control the output voltage generated by them. However, the output voltage produced by the power converter usually carries 07044 l.TW 25265twf.doc/n ripple. This ripple causes the feedback voltage to produce an error' which in turn reduces the accuracy of the output voltage of the power converter. In order to reduce the ripple in the output voltage of the power converter, designers mostly use a low equivalent series resistance (ESR) capacitor to store the output voltage. However, a capacitor with a low equivalent series resistance reduces the damping factor of the output voltage, which in turn causes an unstable oscillation of the output voltage. SUMMARY OF THE INVENTION The present invention provides a power converter with ripple compensation that utilizes a virtual impedance to increase the damping factor of the output voltage and utilizes voltage variations on the second capacitor to achieve ripple compensation. Thereby, the power converter of the present invention will effectively increase the quasi-breaking degree of the output voltage. The present invention provides a power converter having ripple compensation including a voltage conversion device, a partial Kevin circuit, a second resistor, and a second capacitor. And the voltage conversion device includes a filter circuit and a comparator. The voltage conversion device is configured to convert and regulate an input voltage into an output voltage. The filter circuit is configured to filter a pulse signal to obtain the output voltage, wherein the filter circuit comprises an inductor, and the pulse signal is obtained by turning on or off the input voltage. In addition, the comparator is configured to compare the reference voltage with the feedback voltage such that the voltage conversion device adjusts the pulse wave signal according to the output of the comparator, wherein the ratio of the feedback voltage to the wheel-out voltage is an impedance ratio. Furthermore, a portion of the Kevin circuit consists of a first resistor connected in series with a first capacitor, and a portion of the Kevin circuit is connected in parallel with the inductor described above. The second resistor is connected in parallel with a capacitor of 070441 . TW 25265 twf.doc/n, and one end of the second capacitor is coupled to the second resistor, and the other is lightly connected to the output of the thief. Wherein, part of the message circuit forms a complete Kevin circuit with the inductor, so that the current change of the inductor can be reflected on the second resistor through the partial Kevin circuit. In addition, the second resistor and the second capacitor form an AC channel, so that the voltage change on the first capacitor can be transmitted back to the output of the comparator, thereby achieving ripple compensation. On the other hand, the power converter forms a virtual impedance to increase the damping factor of the output voltage, thereby avoiding the occurrence of oscillations. The magnitude of the virtual impedance depends on the resistance of the inductor, the first resistor and the second resistor. The present invention utilizes a virtual impedance to increase the damping factor of the output voltage, and utilizes an AC channel formed by the second resistor and the second capacitor to compensate for the DC error of the output voltage. As such, the present invention will effectively increase the accuracy of the output voltage as compared to conventional techniques. In order to make the above features and advantages of the present invention more comprehensible, the following is a better description of the details of the present invention. [Embodiment] The circuit diagram of the electric waste with the ripple compensation according to the present invention to the embodiment of the present invention. Please refer to the diagram. The power converter 100 includes an electrical (four) UG, a partial hunger circuit 120' resistor R2, and a capacitor ^ homing including a filter circuit (1), a comparator 112, (d) 1 113, a clock generator 114, and a pulse width modulation. The transformer μ, the electrical limit R3 and the heart, and the transistor are combined. 070441.TW 25265twf.doc/n In the voltage conversion device 110, the first source/drain of the transistor T1 receives the input voltage Vin, and the second source/drain is used to generate the pulse signal Sp1. The first source/drain of the transistor T2 is coupled to the second source/drain of the transistor, and the second source/drain is coupled to the ground. The pulse width modulator Π5 is coupled to the gates of the transistors T1 and T2 and is used to control the conduction state of the transistors and T2. The outputs of the clock generator 114 and the comparator U2 are coupled to the pulse width modulator 115. On the other hand, the voltage generator 113 is used to generate a reference voltage Vref. One end of the resistor & is coupled to the output of the voltage converting device 11A, and the other end is used to generate a feedback voltage Vfb. The resistor 4 is coupled between the other end of the resistor R3 and the ground. The comparator 112 will compare the reference voltage Vref received at both ends with the feedback voltage Vfb' such that the voltage conversion device 110 adjusts the pulse signal Sy based on the output of the comparator 112. Furthermore, the filter circuit in is used to filter the pulse signal Spi 15 to the output voltage Vout. Wherein, the ratio of the feedback voltage to the wheel-out voltage 乂(10) is an impedance ratio. In addition, the filter circuit 111 includes an inductor L, a resistor core, and a capacitor C3. The two ends of the inductor L are respectively coupled to the second source/drain of the transistor T1 and the output of the power conversion device 110. The end of the resistor r5 is secreted to the output of the voltage conversion device 11A. Capacitor a is coupled between the other end of the resistor & Where f resistance 115 is the equivalent (four) resistance of the capacitor ^. In the overall operation, when the feedback voltage Vref • I received by the comparator 112 is at the reference voltage Vref, it means that the voltage conversion wheel of the voltage conversion device is lower than a predetermined value. At this time, the pulse width modulator 115 switches the conduction state of the crystals T044 and T2 to increase the duty cycle of the pulse signal Spi. After that, the pulse signal Spi charges and discharges the capacitor C3 through the inductor to generate the wheel voltage. 1. . Conversely, when the feedback voltage Vref is greater than the reference voltage 圻#, the ratio ke 112 causes the pulse width modulator 115 to control the transistor 丨 and Ή 'to further reduce the pulse signal to the electric dust switching device 11 & Cycle of responsibility. It is worth mentioning that the clock generator m is used to generate a clock signal 'and pulse; the skin width modulation n lls is adjusted according to the comparison of the result of the comparison with the result of the f voltage change of the capacitor C2_L, and the fairy signal The adjusted clock signal is used to control the conduction state of the transistor D and 72. In order to make those skilled in the art more aware of the technology of the present embodiment, the operation principle of the voltage converting device 11 and the capacitor C2, the resistor R2, and the portion of the Kevin circuit 120 will be described in detail below. Continuing to refer to FIG. 1 , one end of the capacitor C2 is coupled to the resistor R2 , and the other end of the capacitor C2 is coupled to the output of the comparator 112 . Resistor R2 is connected in parallel with capacitor Ci. In addition, part of the message circuit 12 is composed of a series connected resistor R] and a capacitor h. Here, part of the Kevin circuit 12〇 will form a Wiewen connection (Keivin connecti〇n) by connecting with the inductor l, and then become a complete Kevin circuit. Since the resistor core and the capacitor 〇1 are coupled to the inductor L in a Kevin connection manner, part of the Kevin circuit 12〇 can accurately measure the current change of the inductor L. And the case where this current changes will be reflected on the capacitance C] in the form of the voltage j. In addition, the current flowing through the resistor r2 will also vary with the voltage across the valley C!, which in turn causes a voltage change in the capacitor 1337795 07044 l. TW 25265twf.doc/n C:2. In addition, the resistor R2 and the capacitor C2 form an AC path such that the voltage change on the capacitor 〇2 can be transmitted back to the pulse width modulator 115. Thereby, the pulse width modulator 115 adjusts the conduction state of the transistors T1 and T2 according to the comparison result of the comparator 112 and the voltage on the capacitor C2, thereby achieving the effect of ripple compensation. On the other hand, the capacitor used in the filter circuit is a capacitor having a low equivalent series resistance. In other words, the resistance of the resistor R5 is very low. The main reason is that, as shown in equation (1), the ripple magnitude of the output voltage v〇ut is proportional to the equivalent series resistance R£SR of the capacitor C3.
Vnpple = (RESR + Rout) * Iripp,e (1) 其中’ vripple為輸出電壓Vout的紋波，Irif^e為紋波的電流 值，而Rout則為電壓轉換裝置no的輪出阻抗。 然而，值得注意的是，雖然越小的電阻R5(代表越小 的RESR)越有助於輸出電壓Vout之紋波的降低。然而， 當電容C3的等效串聯電阻過低時，也就是電阻&的電阻 值過低時，輸出電壓Vout的阻尼因數將會不足，進而致使 電源轉換器100產生振盪。為了避免上述問題的發生，本 實施利用一虛擬阻抗VR，來提高輸出電壓vout的阻尼因 數，進而避免振盪現象的發生。其中，虛擬阻抗乂尺的 算式如式(2)所示： VR = L/R! * Cl (2) 另外’本實施例的電源轉換器100更包括電容Co其 中，電谷C4麵接在電源轉換器100的輸入與地端之間，並 1337795 07044 l.TW 25265twf.doc/n 用以作為一輸入穩壓電容。 綜上所述，本發明是利用簡單的被動元件來補償輸出 電壓因紋波而產生的直流誤差。此外，本發明利用一種虛 擬阻抗來提高輸出電壓的阻尼因數，以降低輸出電壓因阻 尼因數不足而有振盡的風險。 雖然本發明已以較佳實施例揭露如上，然其並非用以 限定本發明’任何所屬技術領域中具有通常知識者，在不 脫離本發明之精神和範圍内，當可作些許之更動與潤飾， 因此本發明之保護範圍當視後附之申請專利範圍所界定者 為準。 【圖式簡單說明】 圖1繪示為依據本發明一實施例之具有紋波補償的電 源轉換器的電路圖。 — 【主要元件符號說明】 100 :電源轉換器 110 :電壓轉換裝置 111 :濾波電路 112 :比較器 Π3 :電壓產生器 114 :時脈產生器 115 :脈波寬度調變器 no :部份凱文電路Vnpple = (RESR + Rout) * Iripp,e (1) where ' vripple is the ripple of the output voltage Vout, Irif^e is the ripple current value, and Rout is the wheel-out impedance of the voltage conversion device no. However, it is worth noting that although the smaller the resistor R5 (representing the smaller RESR), the more the ripple of the output voltage Vout is reduced. However, when the equivalent series resistance of the capacitor C3 is too low, that is, when the resistance value of the resistor & is too low, the damping factor of the output voltage Vout will be insufficient, thereby causing the power converter 100 to oscillate. In order to avoid the above problem, the present embodiment uses a virtual impedance VR to increase the damping factor of the output voltage vout, thereby avoiding the occurrence of oscillation. The calculation formula of the virtual impedance is as shown in the formula (2): VR = L/R! * Cl (2) In addition, the power converter 100 of the present embodiment further includes a capacitor Co, and the electric valley C4 is connected to the power source. Between the input of the converter 100 and the ground, and 1137795 07044 l.TW 25265twf.doc/n is used as an input voltage stabilizing capacitor. In summary, the present invention utilizes a simple passive component to compensate for DC errors in the output voltage due to ripple. In addition, the present invention utilizes a virtual impedance to increase the damping factor of the output voltage to reduce the risk of the output voltage being shattered due to insufficient damping factor. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a power converter with ripple compensation according to an embodiment of the present invention. — [Main component symbol description] 100 : Power converter 110 : Voltage conversion device 111 : Filter circuit 112 : Comparator Π 3 : Voltage generator 114 : Clock generator 115 : Pulse width modulator no : Part of Kevin Circuit
11 1337795 07044 l.TW 25265twf.doc/n T1、T2 :電晶體 C广C4 .電容 R]〜R5 .電阻 L :電感 Vin :輸入電壓 Vout :輸出電壓 Vfb :回授電壓 Vref :參考電壓 Spi :脈波訊號11 1337795 07044 l.TW 25265twf.doc/n T1, T2: transistor C wide C4. Capacitor R]~R5. Resistor L: Inductance Vin: Input voltage Vout: Output voltage Vfb: Feedback voltage Vref: Reference voltage Spi: Pulse signal