TW201411999A - Power converter and operating method thereof - Google Patents
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- TW201411999A TW201411999A TW101132214A TW101132214A TW201411999A TW 201411999 A TW201411999 A TW 201411999A TW 101132214 A TW101132214 A TW 101132214A TW 101132214 A TW101132214 A TW 101132214A TW 201411999 A TW201411999 A TW 201411999A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Description
本發明與直流對直流轉換器(DC-DC converter)有關,特別是關於一種由輕載狀態進入重載狀態時之暫態響應(transient response)速度較快的電源轉換器及其操作方法。 The present invention relates to a DC-DC converter, and more particularly to a power converter having a faster transient response speed when entering a heavy load state from a light load state and a method of operating the same.
近年來,電源供應電路已廣泛使用在不同電子產品上,例如可攜式電子產品、電腦產品等。電源供應電路可提供電壓或電流轉換或是提供具有固定電壓或電流之電力以供電子產品使用。在電源供應電路中,電源積體電路(Power integrated circuit,Power IC)為必要的主動元件之一。 In recent years, power supply circuits have been widely used in various electronic products, such as portable electronic products and computer products. The power supply circuit can provide voltage or current conversion or provide power with a fixed voltage or current for use in electronic products. In the power supply circuit, a power integrated circuit (Power IC) is one of the necessary active components.
一般而言,於目前傳統的定頻直流對直流轉換器之操作組態下,當直流對直流轉換器由重載狀態進入輕載狀態時,系統的操作方式將會由連續導通模式進入非連續導通模式,並且其導通週期將會由重載狀態至輕載狀態逐漸縮短。此時,如圖1所示,誤差放大器所輸出的誤差放大訊號Comp很可能會低於斜波產生器所產生之斜波訊號Ramp的底部,而未能與斜波訊號Ramp相交。也就是說,即使當斜波訊號Ramp已由其頂部T2下降至其底部B2時,相對較低的誤差放大訊號Comp仍位於底部B2之下方,而無法與斜波訊號Ramp相交。 Generally speaking, in the current operation configuration of the fixed-frequency DC-to-DC converter, when the DC-to-DC converter enters the light load state from the heavy load state, the operation mode of the system will enter the discontinuous mode from the continuous conduction mode. The conduction mode, and its conduction period will be gradually shortened from the heavy load state to the light load state. At this time, as shown in FIG. 1, the error amplification signal Comp output by the error amplifier is likely to be lower than the bottom of the ramp signal Ramp generated by the ramp generator, and cannot intersect with the ramp signal Ramp. That is, even when the ramp signal Ramp has dropped from its top T2 to its bottom B2, the relatively low error amplification signal Comp is still below the bottom B2 and cannot intersect the ramp signal Ramp.
由於傳統的斜波產生器仍會持續地產生斜波訊號Ramp,當誤差放大訊號Comp再次與斜波訊號Ramp的底部B3相交後,斜波訊號Ramp會由其底部B3上升至較高的位置,使得斜波訊號Ramp與誤差放大訊號Comp相距較遠,因而導致其導通週期較慢開 出,無法提供系統充足的能量,亟待改善。 Since the conventional ramp generator still generates the ramp signal Ramp continuously, when the error amplification signal Comp intersects the bottom B3 of the ramp signal Ramp again, the ramp signal Ramp will rise from the bottom B3 to a higher position. The ramp signal Ramp is far away from the error amplification signal Comp, thus causing the conduction period to be slower. Out, it is impossible to provide sufficient energy for the system and needs to be improved.
同理,在暫態響應上,若是此時系統由輕載狀態進入重載狀態,由於傳統的斜波產生器仍會持續地產生斜波訊號Ramp,使得誤差放大訊號Comp若欲再次與斜波訊號Ramp相交,斜波訊號Ramp已經由其底部上升至較高的位置,斜波訊號Ramp與誤差放大訊號Comp相距較遠,因而導致其輸出級之上橋開關較慢被導通,故其暫態響應速度較慢,亦亟待改善。 Similarly, in the transient response, if the system enters the heavy load state from the light load state at this time, the traditional ramp generator will continue to generate the ramp signal Ramp, so that the error amplification signal Comp has to be ramped again. When the signal Ramp intersects, the ramp signal Ramp has risen from the bottom to the higher position, and the ramp signal Ramp is far away from the error amplification signal Comp, thus causing the bridge switch to be turned on slowly at the output stage, so the transient state The response is slow and needs to be improved.
因此,本發明提出一種電源轉換器及其操作方法,以解決先前技術所遭遇到之上述種種問題。 Accordingly, the present invention provides a power converter and method of operating the same to address the above-discussed problems encountered in the prior art.
本發明之一範疇在於提出一種電源轉換器。於一較佳具體實施例中,該電源轉換器包括零電流偵測單元、斜波產生單元、放大單元及比較單元。零電流偵測單元提供一零電流偵測訊號。斜波產生單元接收零電流偵測訊號及第一開關訊號,並根據零電流偵測訊號產生一斜波訊號。斜波訊號具有第一預設電壓值及第二預設電壓值,且第一預設電壓值高於第二預設電壓值。放大單元根據電源轉換器之一輸出電壓提供一誤差放大訊號。比較單元比較斜波訊號與誤差放大訊號以產生一脈寬調變控制訊號。當斜波訊號達到第二預設電壓值時,若零電流偵測訊號處於高準位,斜波產生單元停止產生斜波訊號,直至第一開關訊號處於高準位為止。 One aspect of the invention is to propose a power converter. In a preferred embodiment, the power converter includes a zero current detecting unit, a ramp generating unit, an amplifying unit, and a comparing unit. The zero current detection unit provides a zero current detection signal. The ramp generating unit receives the zero current detecting signal and the first switching signal, and generates a ramp signal according to the zero current detecting signal. The ramp signal has a first preset voltage value and a second preset voltage value, and the first preset voltage value is higher than the second preset voltage value. The amplifying unit provides an error amplification signal according to an output voltage of one of the power converters. The comparing unit compares the ramp signal with the error amplifying signal to generate a pulse width modulation control signal. When the ramp signal reaches the second preset voltage value, if the zero current detection signal is at the high level, the ramp wave generating unit stops generating the ramp signal until the first switch signal is at the high level.
於一實施例中,電源轉換器為定頻直流-直流電源轉換器。 In one embodiment, the power converter is a fixed frequency DC-DC power converter.
於一實施例中,當電源轉換器由連續導通模式進入非連續導通模式時,若斜波訊號高於誤差放大訊號,斜波產生單元停止產 生斜波訊號。 In an embodiment, when the power converter enters the discontinuous conduction mode from the continuous conduction mode, if the ramp signal is higher than the error amplification signal, the ramp generating unit stops production. Raw ramp signal.
於一實施例中,當電源轉換器由輕載狀態進入重載狀態時,若斜波訊號高於誤差放大訊號,斜波產生單元停止產生斜波訊號。 In an embodiment, when the power converter enters the heavy load state from the light load state, if the ramp signal is higher than the error amplification signal, the ramp generating unit stops generating the ramp signal.
於一實施例中,斜波產生單元包括重設單元及斜波產生電路。重設單元用以接收零電流偵測訊號及第一開關訊號,並輸出控制訊號。斜波產生電路耦接重設單元,用以根據控制訊號停止或繼續產生斜波訊號。 In an embodiment, the ramp wave generating unit includes a reset unit and a ramp generating circuit. The reset unit is configured to receive the zero current detection signal and the first switching signal, and output a control signal. The ramp generating circuit is coupled to the reset unit for stopping or continuing to generate the ramp signal according to the control signal.
於一實施例中,當斜波產生電路所產生之斜波訊號達到第二預設電壓值時,重設單元判斷其接收到之零電流偵測訊號是否處於高準位,若是,重設單元輸出控制訊號控制斜波產生單元停止產生斜波訊號。 In an embodiment, when the ramp signal generated by the ramp generating circuit reaches the second preset voltage value, the reset unit determines whether the zero current detecting signal received by the signal is at a high level, and if so, resets the unit. The output control signal controls the ramp generating unit to stop generating the ramp signal.
於一實施例中,當斜波產生單元停止產生斜波訊號時,重設單元判斷其接收到之第一開關訊號是否處於高準位,若是,重設單元輸出控制訊號控制斜波產生單元繼續產生斜波訊號。 In an embodiment, when the ramp generating unit stops generating the ramp signal, the reset unit determines whether the first switching signal received by the ramping unit is at a high level, and if so, the reset unit outputs a control signal to control the ramp generating unit to continue. Generate a ramp signal.
本發明之另一範疇在於提出一種電源轉換器操作方法。於一具體實施例中,該電源轉換器操作方法用以操作一電源轉換器。該方法包括下列步驟:(a)根據電源轉換器之一輸出電壓提供一誤差放大訊號;(b)接收一零電流偵測訊號及一第一開關訊號;(c)根據零電流偵測訊號產生一斜波訊號,其中斜波訊號具有第一預設電壓值及第二預設電壓值,且第一預設電壓值高於第二預設電壓值,當斜波訊號達到第二預設電壓值時,若零電流偵測訊號處於高準位,停止產生斜波訊號,直至第一開關訊號處於高準位為止;(d)比較斜波訊號與誤差放大訊號以產生一脈寬調變控制訊號。 Another aspect of the present invention is to provide a method of operating a power converter. In one embodiment, the power converter operating method is for operating a power converter. The method comprises the steps of: (a) providing an error amplification signal according to an output voltage of one of the power converters; (b) receiving a zero current detection signal and a first switching signal; (c) generating a zero current detection signal a ramp signal, wherein the ramp signal has a first preset voltage value and a second preset voltage value, and the first preset voltage value is higher than the second preset voltage value, when the ramp signal reaches the second preset voltage When the value is zero, if the zero current detection signal is at the high level, the ramp signal is stopped until the first switching signal is at the high level; (d) the ramp signal and the error amplification signal are compared to generate a pulse width modulation control. Signal.
相較於先前技術,當本發明之電源轉換器由連續導通模式進入非連續導通模式,以及由輕載狀態進入重載狀態時,於斜波訊 號高於誤差放大訊號使得兩者無法相交的情況下,電源轉換器將會控制斜波產生單元停止產生斜波訊號,藉以透過改變斜波訊號之波形的方式增進電源轉換器於輕載狀態下之系統效率,以及提升電源轉換器由輕載狀態進入重載狀態時之暫態響應速度。 Compared with the prior art, when the power converter of the present invention enters the discontinuous conduction mode from the continuous conduction mode and enters the heavy load state from the light load state, the oblique wave signal When the number is higher than the error amplification signal so that the two cannot intersect, the power converter will control the ramp generating unit to stop generating the ramp signal, thereby improving the power converter under the light load condition by changing the waveform of the ramp signal. System efficiency, and the transient response speed of the power converter when it enters the heavy load state from light load state.
關於本發明之優點與精神可以藉由以下的發明詳述及所附圖式得到進一步的瞭解。 The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.
根據本發明之一較佳具體實施例為一種電源轉換器。實際上,本發明提出的電源轉換器應用於定頻直流-直流電源轉換器,但不以此為限。本發明亦可適用於交流對直流轉換器或直流對交流轉換器等電源轉換電路的架構中。 A preferred embodiment of the invention is a power converter. In fact, the power converter proposed by the present invention is applied to a fixed frequency DC-DC power converter, but is not limited thereto. The invention can also be applied to the architecture of a power conversion circuit such as an alternating current to direct current converter or a direct current to alternating current converter.
請參照圖2,圖2繪示此實施例之電源轉換器的電路架構示意圖。如圖2所示,電源轉換器1包括有零電流偵測單元10、斜波產生單元12、放大單元14、比較單元16、第一輸入端17、脈寬調變單元18、第二輸入端19及輸出級20。於此實施例中,輸出級20包括有第一開關201、第二開關202、電壓輸入端203、電壓輸出端204、輸出電感L、第一電阻R1、第二電阻R2、第一電容C1及第二電容C2。其中,第一開關201及第二開關202分別為上橋開關及下橋開關;電壓輸入端203及電壓輸出端204分別用以接收輸入電壓Vin。 Please refer to FIG. 2. FIG. 2 is a schematic diagram showing the circuit architecture of the power converter of this embodiment. As shown in FIG. 2, the power converter 1 includes a zero current detecting unit 10, a ramp generating unit 12, an amplifying unit 14, a comparing unit 16, a first input terminal 17, a pulse width modulation unit 18, and a second input terminal. 19 and output stage 20. In this embodiment, the output stage 20 includes a first switch 201, a second switch 202, a voltage input terminal 203, a voltage output terminal 204, an output inductor L, a first resistor R1, a second resistor R2, and a first capacitor C1. The second capacitor C2. The first switch 201 and the second switch 202 are respectively an upper bridge switch and a lower bridge switch; the voltage input terminal 203 and the voltage output terminal 204 are respectively configured to receive the input voltage Vin.
放大單元14透過第一輸入端17及第二輸入端19分別接收參考電壓VREF及輸出電壓Vout,並且放大單元14輸出誤差放大訊號Comp至比較單元16的正輸入端+。實際上,放大單元14可以將參考電壓VREF及輸出電壓Vout相減並放大為誤差放大訊 號Comp後輸出;輸出電壓Vout為電源轉換器1之輸出級20所輸出的輸出電壓;參考電壓VREF可以是預設的電壓值,但不以此為限。 The amplifying unit 14 receives the reference voltage V REF and the output voltage V out through the first input terminal 17 and the second input terminal 19 respectively, and the amplifying unit 14 outputs the error amplification signal Comp to the positive input terminal + of the comparing unit 16. In fact, the amplifying unit 14 can subtract and amplify the reference voltage V REF and the output voltage V out into an error amplification signal Comp, and output the output voltage V out as an output voltage outputted by the output stage 20 of the power converter 1; V REF can be a preset voltage value, but not limited to this.
於此實施例中,零電流偵測單元10用以偵測流經輸出級20中之輸出電感L的輸出電流IL是否為零。當零電流偵測單元10偵測到輸出電流IL為零時,零電流偵測單元10分別輸出零電流偵測訊號ZC至斜波產生單元12及脈寬調變單元18。原本第一開關201處於關閉狀態且第二開關202處於導通狀態,當脈寬調變單元18接收到零電流偵測訊號ZC時,脈寬調變單元18將會輸出第二開關訊號LG至第二開關202,以關閉原本處於導通狀態的第二開關202,而第一開關201則仍處於關閉狀態。 In this embodiment, the zero current detecting unit 10 is configured to detect whether the output current I L flowing through the output inductor L in the output stage 20 is zero. When the zero current detecting unit 10 detects that the output current I L is zero, the zero current detecting unit 10 outputs the zero current detecting signal ZC to the ramp generating unit 12 and the pulse width modulation unit 18, respectively. When the first switch 201 is in the off state and the second switch 202 is in the on state, when the pulse width modulation unit 18 receives the zero current detection signal ZC, the pulse width modulation unit 18 will output the second switching signal LG to the first The second switch 202 turns off the second switch 202 that is originally in the on state, while the first switch 201 is still in the off state.
如圖3所示,斜波產生單元12可包括有重設單元120及斜波產生電路122。實際上,斜波產生電路可包括振盪器(oscillator)、充電電容及比較器等元件。重設單元120接收零電流偵測訊號ZC及第一開關訊號UG,並輸出控制訊號RST。斜波產生電路122耦接重設單元120,用以根據控制訊號RST停止或繼續產生斜波訊號Ramp。舉例而言,當斜波產生單元12接收到零電流偵測訊號ZC時,斜波產生單元12的斜波產生電路122將會根據零電流偵測訊號ZC產生斜波訊號Ramp至比較單元16之負輸入端-。實際上,斜波訊號Ramp具有第一預設電壓值及第二預設電壓值,且第一預設電壓值高於第二預設電壓值。 As shown in FIG. 3, the ramp generating unit 12 may include a reset unit 120 and a ramp generating circuit 122. In fact, the ramp generating circuit may include components such as an oscillator, a charging capacitor, and a comparator. The reset unit 120 receives the zero current detection signal ZC and the first switching signal UG, and outputs a control signal RST. The ramp generating circuit 122 is coupled to the reset unit 120 for stopping or continuing to generate the ramp signal Ramp according to the control signal RST. For example, when the ramp current generating unit 12 receives the zero current detecting signal ZC, the ramp generating circuit 122 of the ramp generating unit 12 generates the ramp signal Ramp according to the zero current detecting signal ZC to the comparing unit 16. Negative input -. In fact, the ramp signal Ramp has a first preset voltage value and a second preset voltage value, and the first preset voltage value is higher than the second preset voltage value.
當比較單元16分別透過其正輸入端+及負輸入端-接收到誤差放大訊號Comp及斜波訊號Ramp後,比較單元16將會比較誤差放大訊號Comp及斜波訊號Ramp之大小,以產生脈寬調變控制訊號CTL至脈寬調變單元18。 When the comparison unit 16 receives the error amplification signal Comp and the ramp signal Ramp through its positive input terminal + negative input terminal, the comparison unit 16 compares the magnitude of the error amplification signal Comp and the ramp signal Ramp to generate a pulse. The variable control signal CTL is widely modulated to the pulse width modulation unit 18.
若斜波產生電路122產生斜波訊號Ramp時,透過對充電電 容充電方式將斜波訊號Ramp拉升至第一預設電壓值(亦即斜波訊號Ramp頂部)之後,再透過對充電電容放電方式拉低至第二預設電壓值(亦即斜波訊號Ramp底部)。當斜波產生電路122所產生之斜波訊號Ramp達到第二預設電壓值時,重設單元120將會判斷其接收到之零電流偵測訊號ZC是否處於高準位。若是,重設單元120輸出控制訊號RST控制斜波產生電路122停止產生斜波訊號Ramp。 If the ramp wave generating circuit 122 generates the ramp signal Ramp, the charging power is passed through The charging method pulls the ramp signal Ramp to the first preset voltage value (that is, the top of the ramp signal Ramp), and then pulls down the charging capacitor to the second preset voltage value (ie, the ramp signal) Ramp bottom). When the ramp signal Ramp generated by the ramp generating circuit 122 reaches the second preset voltage value, the reset unit 120 determines whether the received zero current detecting signal ZC is at a high level. If so, the reset unit 120 outputs the control signal RST to control the ramp generating circuit 122 to stop generating the ramp signal Ramp.
舉例而言,如圖4所示,當電源轉換器1由重載狀態進入輕載狀態時,負載電流ILoad會隨時間逐漸變小,第一開關201的導通週期長度亦會隨時間逐漸縮短,誤差放大訊號Comp也會隨時間逐漸往下降,而輸出電流IL也會有隨時間逐漸往下降的現象。在週期t4~t5內,當零電流偵測單元10偵測到輸出電流IL為零時,零電流偵測單元10開始產生零電流偵測訊號ZC,直至時間t5,輸出電流IL又開始上升不為零時,零電流偵測單元10才停止產生零電流偵測訊號ZC。 For example, as shown in FIG. 4, when the power converter 1 enters the light load state from the heavy load state, the load current I Load gradually becomes smaller with time, and the conduction period length of the first switch 201 is also gradually shortened with time. The error amplification signal Comp will also gradually decrease with time, and the output current I L will gradually decrease with time. During the period t4~t5, when the zero current detecting unit 10 detects that the output current I L is zero, the zero current detecting unit 10 starts to generate the zero current detecting signal ZC until the time t5, the output current I L starts again. When the rise is not zero, the zero current detecting unit 10 stops generating the zero current detecting signal ZC.
原本第一開關201處於關閉狀態且第二開關202處於導通狀態,當脈寬調變單元18接收到零電流偵測訊號ZC時,脈寬調變單元18將會輸出低準位的第二開關訊號LG至第二開關202,以關閉第二開關202,而第一開關201則仍處於關閉狀態。於時間t5,脈寬調變單元18將會輸出高準位的第一開關訊號UG至第一開關201,以導通第一開關201。直至第一開關201的導通週期結束時,脈寬調變單元18將會分別輸出低準位的第一開關訊號UG及高準位的第二開關訊號LG至第一開關201及第二開關202,以關閉第一開關201且同時導通第二開關202。需說明的是,此時誤差放大訊號Comp雖會隨時間逐漸往下降,但由於誤差放大訊號Comp仍高於斜波訊號Ramp的底部,故重設單元120還不會輸出控制訊號RST控制斜波產生電路122停止產生斜波訊號 Ramp。 When the first switch 201 is in the off state and the second switch 202 is in the on state, when the pulse width modulation unit 18 receives the zero current detection signal ZC, the pulse width modulation unit 18 will output the second switch of the low level. The signal LG is sent to the second switch 202 to turn off the second switch 202, while the first switch 201 is still in the off state. At time t5, the pulse width modulation unit 18 will output the high level first switching signal UG to the first switch 201 to turn on the first switch 201. The pulse width modulation unit 18 outputs the low-level first switching signal UG and the high-level second switching signal LG to the first switch 201 and the second switch 202 respectively until the end period of the first switch 201 is completed. To turn off the first switch 201 and simultaneously turn on the second switch 202. It should be noted that, at this time, the error amplification signal Comp gradually decreases with time, but since the error amplification signal Comp is still higher than the bottom of the ramp signal Ramp, the reset unit 120 does not output the control signal RST to control the ramp wave. The generating circuit 122 stops generating the ramp signal Ramp.
一直到時間t10,斜波訊號Ramp由頂部T10降至底部B10,由於此時誤差放大訊號Comp低於斜波訊號Ramp的底部B10,重設單元120開始發出控制訊號RST至斜波產生電路122,以控制斜波產生電路122停止產生斜波訊號Ramp。由於斜波產生電路122於時間t10開始的第一段時間△K1內停止產生斜波訊號Ramp,因此,在第一段時間△K1內,斜波訊號Ramp將會維持於底部,使得斜波訊號Ramp的波形改變,故可避免先前技術中由於斜波訊號Ramp與誤差放大訊號Comp相距較遠導致其導通週期較慢開出,無法提供系統充足的能量之缺點。 Until time t10, the ramp signal Ramp is reduced from the top T10 to the bottom B10. Since the error amplification signal Comp is lower than the bottom B10 of the ramp signal Ramp, the reset unit 120 starts to send the control signal RST to the ramp generating circuit 122. The ramp signal generating circuit 122 stops generating the ramp signal Ramp. Since the ramp wave generating circuit 122 stops generating the ramp signal Ramp in the first period of time ΔK1 from the time t10, the ramp signal Ramp will be maintained at the bottom during the first period of time ΔK1, so that the ramp signal is The waveform of the Ramp is changed, so that the short circuit of the ramp signal Ramp and the error amplification signal Comp is caused in the prior art, and the conduction period is slow to open, which cannot provide sufficient energy of the system.
需說明的是,於時間t10,脈寬調變單元18並不會輸出高準位的第一開關訊號UG來導通第一開關201。一直到誤差放大訊號Comp又上升至與斜波訊號Ramp相交時,脈寬調變單元18才會輸出高準位的第一開關訊號UG來導通第一開關201。此時,重設單元120將會判斷其接收到之第一開關訊號UG處於高準位,故重設單元UG輸出控制訊號RST控制斜波產生電路122繼續產生斜波訊號122。 It should be noted that, at time t10, the pulse width modulation unit 18 does not output the high level first switching signal UG to turn on the first switch 201. Until the error amplification signal Comp rises again to intersect with the ramp signal Ramp, the pulse width modulation unit 18 outputs the high level first switching signal UG to turn on the first switch 201. At this time, the reset unit 120 will judge that the first switching signal UG received by it is at a high level, so the reset unit UG output control signal RST controls the ramp generating circuit 122 to continue to generate the ramp signal 122.
於時間t11,斜波訊號Ramp由頂部T11降至底部B11,由於此時誤差放大訊號Comp低於斜波訊號Ramp的底部B11,重設單元120開始發出控制訊號RST至斜波產生電路122,以控制斜波產生電路122於第二段時間△K2內停止產生斜波訊號Ramp。不同的是,斜波產生電路122停止產生斜波訊號Ramp的第二段時間△K2將會比上述第一段時間△K1來得長。這現象主要是跟輸出電流IL為零的時間愈來愈長,導致零電流偵測單元10產生零電流偵測訊號ZC的時間愈來愈長有關。 At time t11, the ramp signal Ramp is lowered from the top T11 to the bottom B11. Since the error amplification signal Comp is lower than the bottom B11 of the ramp signal Ramp, the reset unit 120 starts to send the control signal RST to the ramp generating circuit 122 to The control ramp generating circuit 122 stops generating the ramp signal Ramp during the second period of time ΔK2. The difference is that the second period of time ΔK2 at which the ramp generating circuit 122 stops generating the ramp signal Ramp will be longer than the first period ΔK1. This phenomenon is mainly caused by the fact that the output current I L is zero for a longer period of time, and the time for the zero current detecting unit 10 to generate the zero current detecting signal ZC is longer and longer.
同理,於時間t12,斜波訊號Ramp由頂部T12降至底部 B12,由於此時誤差放大訊號Comp低於斜波訊號Ramp的底部B12,重設單元120開始發出控制訊號RST至斜波產生電路122,以控制斜波產生電路122於第三段時間△K3內停止產生斜波訊號Ramp。於時間t13,斜波訊號Ramp由頂部T13降至底部B13,由於此時誤差放大訊號Comp低於斜波訊號Ramp的底部B13,重設單元120開始發出控制訊號RST至斜波產生電路122,以控制斜波產生電路122於第四段時間△K4內停止產生斜波訊號Ramp。 Similarly, at time t12, the ramp signal Ramp is lowered from the top T12 to the bottom. B12, since the error amplification signal Comp is lower than the bottom B12 of the ramp signal Ramp, the reset unit 120 starts to send the control signal RST to the ramp generating circuit 122 to control the ramp generating circuit 122 for the third period of time ΔK3. Stop generating the ramp signal Ramp. At time t13, the ramp signal Ramp is lowered from the top T13 to the bottom B13. Since the error amplification signal Comp is lower than the bottom B13 of the ramp signal Ramp, the reset unit 120 starts to send the control signal RST to the ramp generating circuit 122 to The control ramp generating circuit 122 stops generating the ramp signal Ramp during the fourth period of time ΔK4.
不同的是,第三段時間△K3比上述第二段時間△K2來得長,並且第四段時間△K4比第三段時間△K3來得長。這現象主要是跟輸出電流IL為零的時間愈長,導致零電流偵測單元10產生零電流偵測訊號ZC的時間愈長,因而使得重設單元120發出控制訊號RST控制斜波產生電路122停止產生斜波訊號Ramp的時間亦愈長。 The difference is that the third period of time ΔK3 is longer than the second period of time ΔK2, and the fourth period of time ΔK4 is longer than the third period of time ΔK3. This phenomenon is mainly because the longer the output current I L is zero, the longer the zero current detecting unit 10 generates the zero current detecting signal ZC, so that the reset unit 120 sends the control signal RST to control the ramp generating circuit. 122 The longer the time to stop generating the ramp signal Ramp.
此外,本發明亦可透過改變斜波訊號之波形的方式提升電源轉換器1由輕載狀態進入重載狀態時之暫態響應速度。請參照圖5,圖5繪示當本發明之電源轉換器1由輕載狀態進入重載狀態時,誤差放大訊號Comp上升而與斜波訊號Ramp的底部相交,並立即導通第一開關201以增加暫態響應速度之示意圖。 In addition, the present invention can also improve the transient response speed of the power converter 1 when entering the heavy load state from the light load state by changing the waveform of the ramp signal. Please refer to FIG. 5. FIG. 5 shows that when the power converter 1 of the present invention enters the heavy load state from the light load state, the error amplification signal Comp rises and intersects the bottom of the ramp signal Ramp, and immediately turns on the first switch 201. A schematic diagram of increasing the transient response speed.
如圖5所示,負載電流ILoad於時間t4由原本的低準位變為高準位,代表電源轉換器1於時間t4由原本的輕載狀態開始進入重載狀態,輸出電流IL也隨著電源轉換器1由輕載狀態進入重載狀態而變大。在週期t2~t3內,當零電流偵測單元10偵測到輸出電流IL為零時,零電流偵測單元10開始產生零電流偵測訊號ZC,直至時間t4,輸出電流IL又開始上升不為零時,零電流偵測單元10才停止產生零電流偵測訊號ZC。 As shown in FIG. 5, the load current I Load changes from the original low level to the high level at time t4, indicating that the power converter 1 starts to enter the heavy load state from the original light load state at time t4, and the output current I L also As the power converter 1 enters the heavy load state from the light load state, it becomes large. During the period t2~t3, when the zero current detecting unit 10 detects that the output current I L is zero, the zero current detecting unit 10 starts to generate the zero current detecting signal ZC until the time t4, the output current I L starts again. When the rise is not zero, the zero current detecting unit 10 stops generating the zero current detecting signal ZC.
原本第一開關201處於關閉狀態且第二開關202處於導通狀態,當脈寬調變單元18接收到零電流偵測訊號ZC時,脈寬調變單元18將會輸出低準位的第二開關訊號LG至第二開關202,以關閉第二開關202,而第一開關201則仍處於關閉狀態。於時間t5,脈寬調變單元18將會輸出高準位的第一開關訊號UG至第一開關201,以導通第一開關201。 When the first switch 201 is in the off state and the second switch 202 is in the on state, when the pulse width modulation unit 18 receives the zero current detection signal ZC, the pulse width modulation unit 18 will output the second switch of the low level. The signal LG is sent to the second switch 202 to turn off the second switch 202, while the first switch 201 is still in the off state. At time t5, the pulse width modulation unit 18 will output the high level first switching signal UG to the first switch 201 to turn on the first switch 201.
於時間t3,斜波訊號Ramp由頂部T3降至底部B3,由於此時誤差放大訊號Comp低於斜波訊號Ramp的底部B3,重設單元120開始發出控制訊號RST至斜波產生電路122,以控制斜波產生電路122停止產生斜波訊號Ramp,使得斜波訊號Ramp的波形維持於底部,而不會如同先前技術一樣馬上又繼續往上升至頂部。 At time t3, the ramp signal Ramp is lowered from the top T3 to the bottom B3. Since the error amplification signal Comp is lower than the bottom B3 of the ramp signal Ramp, the reset unit 120 starts to send the control signal RST to the ramp generating circuit 122 to The control ramp generating circuit 122 stops generating the ramp signal Ramp so that the waveform of the ramp signal Ramp is maintained at the bottom without continuing to rise to the top immediately as in the prior art.
接著,於時間t4,電源轉換器1開始由輕載狀態進入重載狀態,負載電流ILoad由原本的低準位變為高準位,輸出電流IL也隨之變大,此時誤差放大訊號Comp亦會由斜波訊號Ramp的底部下方往上升而與斜波訊號Ramp相交。由於此時誤差放大訊號Comp已與斜波訊號Ramp相交,重設單元120輸出控制訊號RST控制斜波產生電路122開始繼續產生斜波訊號Ramp,使得斜波訊號Ramp的波形開始往上升至頂部。 Then, at time t4, the power converter 1 starts to enter the heavy load state from the light load state, the load current I Load changes from the original low level to the high level, and the output current I L also becomes larger, and the error amplification is performed at this time. The signal Comp will also rise from the bottom of the ramp signal Ramp to intersect the ramp signal Ramp. Since the error amplification signal Comp has intersected the ramp signal Ramp, the reset unit 120 outputs the control signal RST to control the ramp generating circuit 122 to continue to generate the ramp signal Ramp, so that the waveform of the ramp signal Ramp starts to rise to the top.
在暫態響應上,當先前技術之電源轉換器由輕載狀態進入重載狀態時,由於傳統的斜波產生器仍會持續地產生斜波訊號Ramp,所以當誤差放大訊號Comp欲再次與斜波訊號Ramp相交時,斜波訊號Ramp已經由其底部上升至較高的位置,使得斜波訊號Ramp與誤差放大訊號Comp相距較遠,因而導致其第一開關需耗費較長時間才會被導通,故其暫態響應速度較慢。相較之下,本發明之電源轉換器1由於有重設單元120開始發出控制 訊號RST控制斜波產生電路122停止產生斜波訊號Ramp,使得斜波訊號Ramp的波形於底部維持一段時間,而不會如同先前技術一樣馬上往上升至頂部,因此,當誤差放大訊號Comp欲再次與斜波訊號Ramp相交時,誤差放大訊號Comp可於時間t4與斜波訊號Ramp的底部相交,脈寬調變單元18即可馬上輸出高準位的第一開關訊號UG導通第一開關201,故其暫態響應速度相當快,有效地提升電源轉換器1由輕載狀態進入重載狀態時之暫態響應速度。 In the transient response, when the prior art power converter enters the heavy load state from the light load state, since the conventional ramp generator still continuously generates the ramp signal Ramp, when the error amplification signal Comp wants to be again and obliquely When the wave signal Ramp intersects, the ramp signal Ramp has risen from the bottom to the higher position, so that the ramp signal Ramp is far away from the error amplification signal Comp, so that the first switch takes a long time to be turned on. Therefore, its transient response speed is slower. In contrast, the power converter 1 of the present invention starts to issue control due to the reset unit 120. The signal RST control ramp generating circuit 122 stops generating the ramp signal Ramp, so that the waveform of the ramp signal Ramp is maintained at the bottom for a period of time, and does not rise to the top immediately as in the prior art. Therefore, when the error amplification signal Comp wants to be again When intersecting with the ramp signal Ramp, the error amplification signal Comp can intersect the bottom of the ramp signal Ramp at time t4, and the pulse width modulation unit 18 can immediately output the high-level first switching signal UG to turn on the first switch 201. Therefore, the transient response speed is relatively fast, effectively improving the transient response speed of the power converter 1 from the light load state to the heavy load state.
本發明之另一具體實施例為一種電源轉換器操作方法。於此實施例中,該電源轉換器操作方法用以操作電源轉換器。請參照圖6,圖6繪示該電源轉換器操作方法之流程圖。如圖6所示,於步驟S10中,該方法根據電源轉換器之一輸出電壓提供一誤差放大訊號。於步驟S12中,該方法接收一零電流偵測訊號及一第一開關訊號。於步驟S14中,該方法根據零電流偵測訊號產生一斜波訊號。其中,斜波訊號具有第一預設電壓值及第二預設電壓值,且第一預設電壓值高於第二預設電壓值。接著,該方法將會比較斜波訊號與誤差放大訊號以產生一脈寬調變控制訊號。 Another embodiment of the present invention is a method of operating a power converter. In this embodiment, the power converter operating method is used to operate the power converter. Please refer to FIG. 6. FIG. 6 is a flow chart showing the operation method of the power converter. As shown in FIG. 6, in step S10, the method provides an error amplification signal according to an output voltage of one of the power converters. In step S12, the method receives a zero current detection signal and a first switching signal. In step S14, the method generates a ramp signal based on the zero current detection signal. The ramp signal has a first preset voltage value and a second preset voltage value, and the first preset voltage value is higher than the second preset voltage value. Next, the method compares the ramp signal with the error amplification signal to generate a pulse width modulation control signal.
該方法執行步驟S16,判斷斜波訊號是否達到第二預設電壓值。若步驟S16的判斷結果為是,該方法執行步驟S18,判斷零電流偵測訊號是否處於高準位。若步驟S18的判斷結果為是,該方法執行步驟S20,停止產生斜波訊號,直至第一開關訊號處於高準位為止。 The method performs step S16 to determine whether the ramp signal reaches the second preset voltage value. If the result of the determination in step S16 is YES, the method proceeds to step S18 to determine whether the zero current detection signal is at a high level. If the result of the determination in step S18 is YES, the method proceeds to step S20 to stop generating the ramp signal until the first switching signal is at the high level.
相較於先前技術,當本發明之電源轉換器由連續導通模式進入非連續導通模式,以及由輕載狀態進入重載狀態時,於斜波訊號高於誤差放大訊號使得兩者無法相交的情況下,電源轉換器將會控制斜波產生單元停止產生斜波訊號,藉以透過改變斜波訊號 之波形的方式增進電源轉換器於輕載狀態下之系統效率,以及提升電源轉換器由輕載狀態進入重載狀態時之暫態響應速度。 Compared with the prior art, when the power converter of the present invention enters the discontinuous conduction mode from the continuous conduction mode and enters the heavy load state from the light load state, the oblique wave signal is higher than the error amplification signal so that the two cannot intersect. Next, the power converter will control the ramp generating unit to stop generating the ramp signal, thereby changing the ramp signal The waveform mode enhances the system efficiency of the power converter under light load conditions and improves the transient response speed of the power converter from a light load state to a heavy load state.
藉由以上較佳具體實施例之詳述,希望能更加清楚描述本發明之特徵與精神,而並非以上述所揭露的較佳具體實施例來對本發明之範疇加以限制。相反地,其目的是希望能涵蓋各種改變及具相等性的安排於本發明所欲申請之專利範圍的範疇內。 The features and spirits of the present invention are more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed.
S10~S20‧‧‧流程步驟 S10~S20‧‧‧ Process steps
RST‧‧‧控制訊號 RST‧‧‧ control signal
B1~B14‧‧‧斜波訊號的底部 B1~B14‧‧‧Bottom of the ramp signal
T1~T14‧‧‧斜波訊號的頂部 Top of the T1~T14‧‧‧ ramp signal
1‧‧‧電源轉換器 1‧‧‧Power Converter
10‧‧‧零電流偵測單元 10‧‧‧Zero current detection unit
12‧‧‧斜波產生單元 12‧‧‧ ramp generation unit
14‧‧‧放大單元 14‧‧‧Amplification unit
16‧‧‧比較單元 16‧‧‧Comparative unit
17‧‧‧第一輸入端 17‧‧‧ first input
18‧‧‧脈寬調變單元 18‧‧‧ Pulse width modulation unit
19‧‧‧第二輸入端 19‧‧‧second input
20‧‧‧輸出級 20‧‧‧Output level
201‧‧‧第一開關 201‧‧‧First switch
202‧‧‧第二開關 202‧‧‧Second switch
203‧‧‧電壓輸入端 203‧‧‧Voltage input
204‧‧‧電壓輸出端 204‧‧‧voltage output
120‧‧‧重設單元 120‧‧‧Reset unit
122‧‧‧斜波產生電路 122‧‧‧ ramp generation circuit
L‧‧‧輸出電感 L‧‧‧Output inductor
R1‧‧‧第一電阻 R1‧‧‧first resistance
R2‧‧‧第二電阻 R2‧‧‧second resistance
C1‧‧‧第一電容 C1‧‧‧first capacitor
C2‧‧‧第二電容 C2‧‧‧second capacitor
Vin‧‧‧輸入電壓 V in ‧‧‧ input voltage
Vout‧‧‧輸出電壓 V out ‧‧‧output voltage
VREF‧‧‧參考電壓 V REF ‧‧‧reference voltage
ZC‧‧‧零電流偵測訊號 ZC‧‧‧ zero current detection signal
Comp‧‧‧誤差放大訊號 Comp‧‧‧Error amplification signal
Ramp‧‧‧斜波訊號 Ramp‧‧‧ ramp signal
UG‧‧‧第一開關訊號 UG‧‧‧First switch signal
LG‧‧‧第二開關訊號 LG‧‧‧Second switch signal
CTL‧‧‧控制訊號 CTL‧‧‧ control signal
Iload‧‧‧負載電流 I load ‧‧‧Load current
+‧‧‧正輸入端 +‧‧‧正Input
-‧‧‧負輸入端 -‧‧‧negative input
IL‧‧‧輸出電流 I L ‧‧‧Output current
t1~t14‧‧‧時間 T1~t14‧‧‧Time
△K1~△K4‧‧‧斜波訊號停止輸出的時間 △K1~△K4‧‧‧The time when the ramp signal stops outputting
圖1繪示傳統的電源轉換器由輕載狀態進入重載狀態時,由於斜波產生器仍持續地產生斜波訊號,導致斜波訊號與誤差放大訊號相距較遠之示意圖。 FIG. 1 is a schematic diagram showing that when a conventional power converter enters a heavy load state from a light load state, the ramp wave generator continuously generates a ramp signal, thereby causing the oblique wave signal to be far apart from the error amplification signal.
圖2繪示根據本發明之一具體實施例之電源轉換器的電路架構示意圖。 2 is a schematic diagram showing the circuit architecture of a power converter according to an embodiment of the present invention.
圖3繪示圖2中之斜波產生單元包括有重設單元與斜波產生電路之功能方塊圖。 3 is a functional block diagram of the ramp generating unit of FIG. 2 including a reset unit and a ramp generating circuit.
圖4繪示當本發明之電源轉換器由重載狀態進入輕載狀態時,一旦誤差放大訊號低於斜波訊號的底部,斜波產生器即停止產生斜波訊號,使得斜波訊號與誤差放大訊號相距較近之示意圖。 4 shows that when the power converter of the present invention enters the light load state from the heavy load state, once the error amplification signal is lower than the bottom of the ramp signal, the ramp generator stops generating the ramp signal, so that the ramp signal and the error A schematic diagram in which the amplified signals are closer together.
圖5繪示當本發明之電源轉換器由輕載狀態進入重載狀態時,誤差放大訊號上升而與斜波訊號的底部相交,並立即導通第一開關以增加暫態響應速度之示意圖。 FIG. 5 is a schematic diagram showing when the power converter of the present invention enters the heavy load state from the light load state, the error amplification signal rises to intersect the bottom of the ramp signal, and immediately turns on the first switch to increase the transient response speed.
圖6繪示根據本發明之另一具體實施例之電源轉換器操作方法的流程圖。 6 is a flow chart showing a method of operating a power converter in accordance with another embodiment of the present invention.
1‧‧‧電源轉換器 1‧‧‧Power Converter
10‧‧‧零電流偵測單元 10‧‧‧Zero current detection unit
12‧‧‧斜波產生單元 12‧‧‧ ramp generation unit
14‧‧‧放大單元 14‧‧‧Amplification unit
16‧‧‧比較單元 16‧‧‧Comparative unit
17‧‧‧第一輸入端 17‧‧‧ first input
18‧‧‧脈寬調變單元 18‧‧‧ Pulse width modulation unit
19‧‧‧第二輸入端 19‧‧‧second input
20‧‧‧輸出級 20‧‧‧Output level
201‧‧‧第一開關 201‧‧‧First switch
202‧‧‧第二開關 202‧‧‧Second switch
203‧‧‧電壓輸入端 203‧‧‧Voltage input
204‧‧‧電壓輸出端 204‧‧‧voltage output
L‧‧‧輸出電感 L‧‧‧Output inductor
R1‧‧‧第一電阻 R1‧‧‧first resistance
R2‧‧‧第二電阻 R2‧‧‧second resistance
C1‧‧‧第一電容 C1‧‧‧first capacitor
C2‧‧‧第二電容 C2‧‧‧second capacitor
Vin‧‧‧輸入電壓 Vin‧‧‧Input voltage
Vout‧‧‧輸出電壓 Vout‧‧‧ output voltage
VREF‧‧‧參考電壓 V REF ‧‧‧reference voltage
ZC‧‧‧零電流偵測訊號 ZC‧‧‧ zero current detection signal
Comp‧‧‧誤差放大訊號 Comp‧‧‧Error amplification signal
Ramp‧‧‧斜波訊號 Ramp‧‧‧ ramp signal
UG‧‧‧第一開關訊號 UG‧‧‧First switch signal
LG‧‧‧第二開關訊號 LG‧‧‧Second switch signal
Claims (10)
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