TWI514709B

TWI514709B - Control methods for over voltage protection and relevant power controllers

Info

Publication number: TWI514709B
Application number: TW103108276A
Authority: TW
Inventors: Chen Lun Yang; Ren Yi Chen; Shun Chin Chou
Original assignee: Grenergy Opto Inc
Priority date: 2014-03-11
Filing date: 2014-03-11
Publication date: 2015-12-21
Also published as: TW201535907A

Description

過電壓保護控制方法與相關之電源控制器Overvoltage protection control method and related power controller

本說明書所揭示的技術大致相關於電源轉換器之過電壓保護。The techniques disclosed in this specification are generally related to overvoltage protection of power converters.

電源轉換器都需要有配置一些保護的功能，來預防異常事件發生時，對於人體或環境所造成的危害。舉例來說，驅動發光二極體(light emitting diode)來做為照明之電源轉換器，就需要有過電壓保護(over voltage protection，OVP)的功能，來防止過高的輸出電壓，對於人體所可能造成的衝擊。Power converters need to be equipped with some protection features to prevent human or environmental damage caused by abnormal events. For example, driving a light emitting diode as a power converter for illumination requires over voltage protection (OVP) to prevent excessive output voltage. Possible impact.

第1圖為習知的電源轉換器10。橋式整流器12提供全波整流的功能，以市電來的交流電壓V_AC 為輸入，產生整流後直流電壓V_IN 以及一接地線。電源轉換器10屬於一降壓轉換器，其LED模組14做為負載，與變壓器的主繞組PRM串接在一起，連接在整流後直流電壓V_IN 以及接地線之間。電源控制器17具有功率開關18。當功率開關18開啟時，LED模組14發光，主繞組PRM可以儲能。當功率開關18關閉時，原先存放在主繞組PRM中的電能，可以透過飛輪二極體(wheel diode)16，繼續驅動LED模組14發光。電流偵測電阻20可以提供電源控制器17流經功率開關18的電流偵測信號V_CS 。FIG. 1 is a conventional power converter 10. The bridge rectifier 12 provides a full-wave rectification function, taking the AC voltage V _AC from the _mains as an input, and generating a rectified DC voltage V _IN and a ground line. The power converter 10 belongs to a buck converter, and the LED module 14 is used as a load, and is connected in series with the main winding PRM of the transformer, and is connected between the rectified DC voltage V _IN and the ground line. The power controller 17 has a power switch 18. When the power switch 18 is turned on, the LED module 14 emits light, and the main winding PRM can store energy. When the power switch 18 is turned off, the electric energy originally stored in the main winding PRM can be transmitted through the flywheel diode 16 to continue to drive the LED module 14 to emit light. The current detecting resistor 20 can provide a current detecting signal V _CS that the power controller 17 flows through the power switch 18.

當LED模組14發生開路事件時，也就是其中至少有一LED不導通時，如果沒有OVP機制，驅動電壓V_LED 將會飆高。此時，萬一人接觸到LED模組14的兩個終端，會有被電擊的危險。When the LED module 14 has an open event, that is, when at least one of the LEDs is not turned on, if there is no OVP mechanism, the driving voltage V _LED will be high. At this time, if one touches the two terminals of the LED module 14, there is a danger of being shocked.

因此，第1圖中的電源控制器17透過VOP端、分壓器22、以及變壓器的二次繞組SEC，來偵測驅動電壓V_LED 。當變壓器釋能時，主繞組PRM的跨壓大約等於驅動電壓V_LED 與飛輪二極體16之順向偏壓(forward voltage)的合，而二次繞組SEC的跨壓比例於主繞組PRM的跨壓。因此，當變壓器釋能時，如果VOP端之電壓超過一預設標準，可以表示驅動電壓V_LED 已經過高了，電源控制器17就持續關閉功率開關18，停止電源轉換器10的電能轉換。如此，達到OVP的效果。Therefore, the power supply controller 17 in FIG. 1 detects the driving voltage V _LED through the VOP terminal, the voltage divider 22, and the secondary winding SEC of the transformer. When the transformer is released, the voltage across the main winding PRM is approximately equal to the forward voltage of the driving voltage V _LED and the flywheel diode 16 , and the voltage across the secondary winding SEC is proportional to the main winding PRM. Cross pressure. Therefore, when the transformer is released, if the voltage of the VOP terminal exceeds a predetermined standard, it can be said that the driving voltage V _{LED is} already too high, and the power controller 17 continuously turns off the power switch 18 to stop the power conversion of the power converter 10. In this way, the effect of OVP is achieved.

實施例揭示有一種過電壓保護控制方法，適用於一電源轉換器，其包含有一整流器，用以將一交流電壓，整流為一整流後直流電壓。該過電壓控制方法包含有：判斷該整流後直流電壓是否位於一局部最低值；提供一偵測電壓，其可代表該整流後直流電壓；比較該偵測電壓與一過電壓參考電壓；以及，當該整流後直流電源位於該局部最低值，且該偵測電壓低於該過電壓參考電壓時，提供一過電壓保護信號，以停止該電源轉換器之電能轉換。The embodiment discloses an overvoltage protection control method suitable for a power converter including a rectifier for rectifying an AC voltage into a rectified DC voltage. The overvoltage control method includes: determining whether the rectified DC voltage is at a local minimum value; providing a detection voltage representative of the rectified DC voltage; comparing the detection voltage with an overvoltage reference voltage; When the rectified DC power source is at the local minimum value, and the detection voltage is lower than the overvoltage reference voltage, an overvoltage protection signal is provided to stop the power conversion of the power converter.

實施例揭示有一種種電源控制器，適用於一電源轉換器。該電源轉換器包含有一整流器，用以將一交流市電壓，整流為一整流後直流電壓。該電源控制器包含有一波谷偵測器、一過電壓比較器、以及一邏輯電路。該波谷偵測器用以判斷該整流後直流電壓是否位於一局部最低值。該過電壓比較器用以比較一偵測電壓以及一過電壓參考電壓。該偵測電壓可代表該整流後直流電壓。當該整流後直流電壓位於該局部最低值，且該偵測電壓高於該過電壓參考電壓時，該邏輯電路用以提供一過電壓保護信號，以停止該電源轉換器之電能轉換。The embodiment discloses a power supply controller suitable for use in a power converter. The power converter includes a rectifier for rectifying an AC voltage to a rectified DC voltage. The power controller includes a valley detector, an overvoltage comparator, and a logic Circuit. The valley detector is configured to determine whether the rectified DC voltage is at a local minimum. The overvoltage comparator is configured to compare a detected voltage with an overvoltage reference voltage. The detected voltage can represent the rectified DC voltage. When the rectified DC voltage is at the local minimum value, and the detection voltage is higher than the overvoltage reference voltage, the logic circuit is configured to provide an overvoltage protection signal to stop the power conversion of the power converter.

10‧‧‧電源轉換器10‧‧‧Power Converter

12‧‧‧橋式整流器12‧‧‧Bridge rectifier

14‧‧‧LED模組14‧‧‧LED module

16‧‧‧飛輪二極體16‧‧‧Flywheel diode

17‧‧‧電源控制器17‧‧‧Power Controller

18‧‧‧功率開關18‧‧‧Power switch

20‧‧‧電流偵測電阻20‧‧‧ Current Sense Resistor

22‧‧‧分壓器22‧‧‧Divider

60‧‧‧電源轉換器60‧‧‧Power Converter

62‧‧‧電源控制器62‧‧‧Power Controller

64、66‧‧‧分壓電阻64, 66‧‧ ‧ voltage divider resistor

79‧‧‧波谷偵測器79‧‧‧ Valley Detector

80‧‧‧波谷比較器80‧‧‧Valley Comparator

81‧‧‧延遲時間產生器81‧‧‧Delay time generator

82‧‧‧過電壓比較器82‧‧‧Overvoltage comparator

83‧‧‧邏輯電路83‧‧‧Logical circuits

84‧‧‧斜坡信號產生器84‧‧‧Ramp signal generator

86‧‧‧比較器86‧‧‧ comparator

88‧‧‧邏輯電路88‧‧‧Logical Circuit

CS‧‧‧電流偵測端CS‧‧‧current detection terminal

I_CS ‧‧‧電流I _CS ‧‧‧current

I_CS-PEAK ‧‧‧電流I_CS 的峰值I _CS-PEAK ‧‧‧current I _CS peak

L‧‧‧電感L‧‧‧Inductance

PRM‧‧‧主繞組PRM‧‧‧ main winding

SEC‧‧‧二次繞組SEC‧‧‧second winding

S_Protection ‧‧‧過電壓保護信號S _Protection ‧‧‧Overvoltage protection signal

t_LED-OPEN ‧‧‧時間t _LED-OPEN ‧‧‧Time

t_OVP ‧‧‧時間t _OVP ‧‧‧Time

T_OVP-DELAY ‧‧‧預設時間T _OVP-DELAY ‧‧‧Preset time

V_AC ‧‧‧交流電壓V _AC ‧‧‧AC voltage

V_COMP ‧‧‧補償信號V _COMP ‧‧‧compensation signal

V_CS ‧‧‧電流偵測信號V _CS ‧‧‧ current detection signal

V_CS-REF ‧‧‧預設值V _CS-REF ‧‧‧Preset value

V_IN ‧‧‧整流後直流電壓V _IN ‧‧‧Rectified DC voltage

VL₁ 、VL₂ ‧‧‧波谷VL ₁ , VL ₂ ‧‧‧ trough

V_LED ‧‧‧驅動電壓V _LED ‧‧‧ drive voltage

VOP‧‧‧端VOP‧‧‧

V_OVP-REF ‧‧‧過電壓參考電壓V _OVP-REF ‧‧‧Overvoltage reference voltage

V_PF ‧‧‧偵測電壓V _PF ‧‧‧Detection voltage

V_RAMP ‧‧‧斜坡信號V _RAMP ‧‧‧Ramp signal

第1圖為習知的電源轉換器。Figure 1 is a conventional power converter.

第2圖舉例依據本發明所實施的一電源轉換器。Figure 2 illustrates a power converter implemented in accordance with the present invention.

第3圖舉例電源控制器以及一些周邊元件。Figure 3 illustrates a power controller and some peripheral components.

第4圖顯示關於第2圖與第3圖的一些信號波形。Figure 4 shows some of the signal waveforms for Figures 2 and 3.

儘管第1圖中的電源轉換器10可以提供OVP機制，但是電源轉換器10需要有主繞組PRM與二次繞組SEC所構成的變壓器。相對於一般的電感，變壓器是比較大且貴。Although the power converter 10 in FIG. 1 can provide an OVP mechanism, the power converter 10 requires a transformer composed of a main winding PRM and a secondary winding SEC. The transformer is relatively large and expensive compared to the general inductance.

在本說明書中，相同符號之元件表示具有相同或是類似功能之元件，其細節與變化，因為可被此業界具有一般技術者依據本說明書所推知，因此不一定在此說明書中細細說明。In the specification, elements having the same symbols indicate elements having the same or similar functions, and the details and variations thereof may be inferred from the specification by those skilled in the art, and thus are not necessarily described in detail in this specification.

第2圖舉例依據本發明所實施的一電源轉換器60，其具有一電感L，取代了第1圖中的變壓器。電源轉換器60不需要變壓器就可以達到OVP的功能。但是，這並非限制本發明之實施例不可以有變壓器。舉例來說，在一些實施例中，電感L可以屬於一變壓器之數個繞組中的一繞組。Figure 2 illustrates a power converter 60 implemented in accordance with the present invention having an inductance L in place of the transformer of Figure 1. The power converter 60 can achieve the function of the OVP without a transformer. However, this does not limit the embodiment of the invention and may not have a transformer. For example, in some embodiments, the inductance L can belong to one of a plurality of windings of a transformer.

分壓電阻64與66串接於整流後直流電壓V_IN 與接地線GND之間，用以提供一偵測電壓V_PF ，其大致比例於整流後直流電壓V_IN 。The voltage dividing resistors 64 and 66 are connected in series between the rectified DC voltage V _IN and the ground line GND to provide a detection voltage V _PF which is approximately proportional to the rectified DC voltage V _IN .

在第2圖之實施例中，電源控制器62使電源轉換器60大約操作在臨界模式(boundary mode)。一般而言，在每次開關週期開始時，電感L都沒有存放任何電能，如此的操作模式稱為非連續導通模式(dis-continuous conduction mode，DCM)；而在開關週期開始時，電感L還有一些電能沒有釋放完畢，如此的操作模式一般稱為連續導通模式(continuous conduction mode，CCM)。臨界模式介於DCM與CCM之間，一般指的是當電感L剛剛放完電能，就立刻開始下一開關週期的操作模式。In the embodiment of Figure 2, power controller 62 causes power converter 60 to operate approximately in a critical mode. In general, the inductor L does not store any power at the beginning of each switching cycle. Such an operation mode is called a discontinuous conduction mode (DCM); at the beginning of the switching cycle, the inductor L is also Some power is not released, and such an operation mode is generally called a continuous conduction mode (CCM). The critical mode is between DCM and CCM. Generally speaking, when the inductor L has just discharged the power, it starts the operation mode of the next switching cycle.

當電源控制器62中的功率開關導通時，電感L可以開始儲能，其電壓電流應符合以下公式(I)：V_L * T_ON =L_L * I_L When the power switch in the power controller 62 is turned on, the inductor L can start to store energy, and its voltage and current should meet the following formula (I): V _L * T _ON = L _L * I _L

(V_IN -V_LED )* T_ON =L_L * I_CS-PEAK ....(I)(V _IN -V _LED )* T _ON =L _L * I _CS-PEAK ....(I)

其中，V_L 與I_L 分別表示電感L的跨壓與電流；L_L 為電感L的感量；T_ON 為電源控制器62中之功率開關的導通時間；I_CS-PEAK 為流經電流偵測電阻20之電流I_CS 的峰值。Wherein, V _L and I _L respectively represent the voltage across the inductor L and the current; L _L is the inductance of the inductor L; T _ON is the conduction time of the power switch in the power controller 62; I _CS-PEAK is the current through the current sense The peak value of the current I _CS of the resistor 20 is measured.

從公式(I)可以發現，當整流後直流電壓V_IN 小於等於驅動電壓V_LED 時，峰值I_CS-PEAK 大約會為0，電感L停止儲能。此時，如果交流電壓V_AC 的絕對值小於整流後直流電壓V_IN ，因為電感L沒有消耗能量，所以整流後直流電壓V_IN 大會停在一個定值，大約就是驅動電壓V_LED 。當交流電壓V_AC 的絕對值大於整流後直流電壓V_IN ，橋式整流器12會使整流後直流電壓V_IN 追隨交流電壓V_AC 的絕對值。換言之，整流後直流電壓V_IN 的局部最低值，大約會等於驅動電壓V_LED 。From equation (I), it can be found that when the rectified DC voltage V _{IN is} less than or equal to the driving voltage V _LED , the peak value I _{CS-PEAK will be} approximately 0, and the inductor L stops storing energy. At this time, if the absolute value of the AC voltage V _AC is smaller than the rectified DC voltage V _IN , since the inductor L does not consume energy, the rectified DC voltage V _{IN is} stopped at a constant value, which is approximately the driving voltage V _LED . When the absolute value of the AC voltage V _AC is greater than the rectified DC voltage V _IN , the bridge rectifier 12 causes the rectified DC voltage V _{IN to} follow the absolute value of the AC voltage V _AC . In other words, the local minimum of the rectified DC voltage V _IN is approximately equal to the drive voltage V _LED .

因此，本發明的一些實施例偵測整流後直流電壓V_IN 的最小值，來判斷是否應該觸發過電壓保護。Therefore, some embodiments of the present invention detect the minimum value of the rectified DC voltage V _IN to determine whether overvoltage protection should be triggered.

第2圖中的電源控制器62可以透過電流偵測端CS上的電流偵測信號V_CS ，來判斷整流後直流電壓V_IN 是否位於一局部最低值，換言之，判斷整流後直流電壓V_IN 是否到達一個波谷。舉例來說，當電流偵測信號V_CS 小於一定預設值V_CS-REF 時，且持續一預設時間後，電源控制器62認定整流後直流電壓V_IN 位於一局部最低值。此時，整流後直流電壓V_IN 應該等於驅動電壓V_LED 。The power supply controller 62 of FIG. 2 may be transmitted through the current detection signal V _CS to the CS terminal of the current detection, to determine the rectified DC voltage V _IN is located at a local minimum value, in other words, after determining whether the rectified DC voltage V _IN Arrived in a trough. For example, when the current detection signal V _{CS is} less than a certain preset value V _CS-REF and continues for a predetermined time, the power controller 62 determines that the rectified DC voltage V _IN is at a local minimum value. At this time, the rectified DC voltage V _IN should be equal to the driving voltage V _LED .

電源控制器62可以比較偵測電壓V_PF 以及一過電壓參考電壓V_OVP-REF 。在整流後直流電壓V_IN 位於一局部最低值時，如果偵測電壓V_PF 超過了過電壓參考電壓V_OVP-REF ，那意味著驅動電壓V_LED 已經過高了。此時，電源控制器62可以據以提供一過電壓保護信號S_Protection ，以停止電源轉換器60之電能轉換。The power controller 62 can compare the detection voltage V _PF with an overvoltage reference voltage V _OVP-REF . When the rectified DC voltage V _IN is at a local minimum value, if the detection voltage V _PF exceeds the overvoltage reference voltage V _OVP-REF , it means that the driving voltage V _{LED is} already too high. At this time, the power controller 62 can provide an overvoltage protection signal S _Protection to stop the power conversion of the power converter 60.

第3圖舉例電源控制器62以及一些周邊元件。電源控制器62包含有波谷偵測器79、過電壓比較器82、斜坡信號產生器84、邏輯電路83與88等。Figure 3 illustrates a power controller 62 and some peripheral components. The power controller 62 includes a valley detector 79, an overvoltage comparator 82, a ramp signal generator 84, logic circuits 83 and 88, and the like.

波谷偵測器79包含有波谷比較器80以及延遲時間產生器81。波谷比較器80比較電流偵測信號V_CS 以及預設值V_CS-REF ，預設值V_CS-REF 在一實施例中為50mV。當波谷比較器80持續一段預設時間T_OVP-DELAY 都認定電流偵測信號V_CS 小於預設值V_CS-REF 時，延遲時間產生器81使其輸出為邏輯上的1，做為一確認信號，表示此時整流後直流電壓V_IN 位於一局部最低值。The valley detector 79 includes a valley comparator 80 and a delay time generator 81. The valley comparator 80 compares the current detection signal V _CS with a preset value V _CS-REF , and the preset value V _CS-REF is 50 mV in one embodiment. When the valley comparator 80 continues for a preset time T _OVP-DELAY to determine that the current detection signal V _{CS is} less than the preset value V _CS-REF , the delay time generator 81 causes its output to be a logical one as a confirmation. The signal indicates that the rectified DC voltage V _IN is at a local minimum.

當整流後直流電壓V_IN 位於一局部最低值，且過電壓比較器82判定偵測電壓V_PF 高於過電壓參考電壓V_OVP-REF 時，邏輯電路83提供過電壓保護信號S_Protection ，使邏輯電路88持續關閉功率開關18，以停止電源轉換器60之電能轉換，達成過電壓保護的目的。When the rectified DC voltage V _IN is at a local minimum value, and the overvoltage comparator 82 determines that the detection voltage V _{PF is} higher than the overvoltage reference voltage V _OVP-REF , the logic circuit 83 provides an overvoltage protection signal S _Protection to enable logic The circuit 88 continuously turns off the power switch 18 to stop the power conversion of the power converter 60 for the purpose of overvoltage protection.

斜坡信號產生器84提供斜坡信號V_RAMP ，其信號斜率是依據偵測電壓V_PF 的峰值而決定。舉例來說，偵測電壓V_PF 的峰值可以被電源控制器62偵測並記錄，其可以代表交流電壓V_AC 的振幅。在一實施例中，偵測電壓V_PF 的峰值越高，斜坡信號V_RAMP 的信號斜率越大。斜坡信號V_RAMP 與補償信號V_COMP 分別送至比較器86的二輸入端。舉例來說，當功率開關18開始導通時，斜坡信號V_RAMP 從0V開始上升。當斜坡信號V_RAMP 超過補償信號V_COMP 時，比較器86使得邏輯電路88關閉功率開關18。因此，斜坡信號產生器84與比較器86可以決定功率開關18的開啟時間(ON time)。The ramp signal generator 84 provides a ramp signal V _RAMP whose signal slope is determined based on the peak value of the detected voltage V _PF . For example, the peak value of the detection voltage V _PF can be detected and recorded by the power controller 62, which can represent the amplitude of the AC voltage V _AC . In one embodiment, the higher the peak value of the detection voltage V _PF , the greater the slope of the signal of the ramp signal V _RAMP . The ramp signal V _RAMP and the compensation signal V _COMP are supplied to the two inputs of the comparator 86, respectively. For example, when the power switch 18 begins to conduct, the ramp signal V _RAMP rises from 0V. Comparator 86 causes logic circuit 88 to turn off power switch 18 when ramp signal V _RAMP exceeds compensation signal V _COMP . Therefore, the ramp signal generator 84 and the comparator 86 can determine the ON time of the power switch 18.

第4圖顯示關於第2圖與第3圖的一些信號波形。交流電壓V_AC 是一正弦波，舉例來說，其振幅為110V，頻率為60Hz。如同第4圖所示，整流後直流電壓V_IN 在每個波谷中的局部最低值，大概等於驅動電壓V_LED 。偵測電壓V_PF 大致比例於整流後直流電壓V_IN 。Figure 4 shows some of the signal waveforms for Figures 2 and 3. The AC voltage V _AC is a sine wave, for example, having an amplitude of 110 V and a frequency of 60 Hz. As shown in Figure 4, the local minimum of the rectified DC voltage V _IN in each valley is approximately equal to the drive voltage V _LED . The detection voltage V _PF is approximately proportional to the rectified DC voltage V _IN .

第4圖中，假設第2圖中的LED模組14從時間t_LED-OPEN ，開始錯誤地開路(open)。因此，隨著功率開關18的開開關關，驅動電壓V_LED 漸漸的上升。In Fig. 4, it is assumed that the LED module 14 in Fig. 2 starts to open erroneously from the time t _LED-OPEN . Therefore, as the power switch 18 is turned on and off, the driving voltage V _LED gradually rises.

在時間t_LED-OPEN 之後，整流後直流電壓V_IN 的波形出現了第一個波谷VL₁ 。此時，過電壓保護還沒有被觸發，因為偵測電壓V_PF 還沒有高於過電壓參考電壓V_OVP-REF 。After the time t _LED-OPEN , the waveform of the rectified DC voltage V _IN appears the first valley VL ₁ . At this time, the overvoltage protection has not been triggered because the detection voltage V _PF is not higher than the overvoltage reference voltage V _OVP-REF .

在第一個波谷VL₁ 之後，整流後直流電壓V_IN 的波形出現了第二個波谷VL₂ 。此時，偵測電壓V_PF 已經高於過電壓參考電壓V_OVP-REF 。因此，在電流偵測信號V_CS 持續大約等於0(小於預設值V_CS-REF )有預設時間T_OVP-DELAY 之後的時間t_OVP ，就觸發了過電壓保護。因此，在時間t_OVP 之後，電流偵測信號V_CS 一直為0，因為功率開關18持續關閉。After the first trough VL ₁ , the waveform of the rectified DC voltage V _IN exhibits a second trough VL ₂ . At this time, the detection voltage V _{PF is} already higher than the overvoltage reference voltage V _OVP-REF . Therefore, the overvoltage protection is triggered when the current detection signal V _CS continues to be approximately equal to 0 (less than the preset value V _CS-REF ) for a time t _OVP after a preset time T _OVP-DELAY . Therefore, after time t _OVP , the current detection signal V _{CS is} always 0 because the power switch 18 is continuously turned off.

不同於第1圖需要有變壓器，第2圖中電源轉換器60可以用一電感取而代之，一樣可以具有過電壓防護之功能。因此，第2圖中電源轉換器60可以在產品大小以及成本上，都比較有競爭力。Unlike the first figure, a transformer is required. In the second figure, the power converter 60 can be replaced by an inductor, and the same function as overvoltage protection can be achieved. Therefore, the power converter 60 in Fig. 2 can be competitive in terms of product size and cost.

以上所述僅為本發明之較佳實施例，凡依本發明申請專利範圍所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

18‧‧‧功率開關18‧‧‧Power switch

62‧‧‧電源控制器62‧‧‧Power Controller

64、66‧‧‧分壓電阻64, 66‧‧ ‧ voltage divider resistor

79‧‧‧波谷偵測器79‧‧‧ Valley Detector

80‧‧‧波谷比較器80‧‧‧Valley Comparator

81‧‧‧延遲時間產生器81‧‧‧Delay time generator

82‧‧‧過電壓比較器82‧‧‧Overvoltage comparator

83‧‧‧邏輯電路83‧‧‧Logical circuits

84‧‧‧斜坡信號產生器84‧‧‧Ramp signal generator

86‧‧‧比較器86‧‧‧ comparator

88‧‧‧邏輯電路88‧‧‧Logical Circuit

V_COMP ‧‧‧補償信號V _COMP ‧‧‧compensation signal

V_CS ‧‧‧電流偵測信號V _CS ‧‧‧ current detection signal

V_CS-REF ‧‧‧預設值V _CS-REF ‧‧‧Preset value

V_IN ‧‧‧整流後直流電壓V _IN ‧‧‧Rectified DC voltage

V_PF ‧‧‧偵測電壓V _PF ‧‧‧Detection voltage

V_RAMP ‧‧‧斜坡信號V _RAMP ‧‧‧Ramp signal

Claims

一種過電壓保護控制方法，適用於一電源轉換器，其包含有一整流器，用以將一交流電壓，整流為一整流後直流電壓，該過電壓控制方法包含有：判斷該整流後直流電壓是否位於一局部最低值(local minimum)；提供一偵測電壓，其可代表該整流後直流電壓；比較該偵測電壓與一過電壓參考電壓；以及當該整流後直流電源位於該局部最低值，且該偵測電壓高於該過電壓參考電壓時，提供一過電壓保護信號，以停止該電源轉換器之電能轉換。 An overvoltage protection control method is applicable to a power converter, comprising a rectifier for rectifying an AC voltage into a rectified DC voltage, the overvoltage control method comprising: determining whether the rectified DC voltage is located a local minimum; providing a detection voltage representative of the rectified DC voltage; comparing the detection voltage to an overvoltage reference voltage; and when the rectified DC power source is at the local minimum value, and When the detection voltage is higher than the overvoltage reference voltage, an overvoltage protection signal is provided to stop the power conversion of the power converter.

如同申請專利範圍第1項之該過電壓保護控制方法，其中，該電源轉換器包含有串聯之一電感、一光源負載、以及一功率開關，該判斷步驟包含有：提供一電流偵測信號，其可代表流經該功率開關之一電流；比較該電流偵測信號以及一預設值；以及當該電流偵測信號低於該預設值後，決定該整流後直流電壓位於該局部最低值。 The overvoltage protection control method of claim 1, wherein the power converter comprises a series inductance, a light source load, and a power switch, and the determining step comprises: providing a current detection signal, It may represent a current flowing through the power switch; compare the current detection signal with a preset value; and when the current detection signal is lower than the preset value, determine that the rectified DC voltage is at the local minimum value .

如同申請專利範圍第2項之該過電壓保護控制方法，包含有：當該電流偵測信號持續低於該預設值一預設時間後，決定該整流後直流電壓位於該局部最低值。 The overvoltage protection control method as claimed in claim 2 includes: determining that the rectified DC voltage is at the local minimum value after the current detection signal continues to be lower than the preset value for a predetermined time.

如同申請專利範圍第1項之該過電壓保護控制方法，其中，該電源轉換器包含有串聯之一電感、一光源負載、以及一功率開關，該電源轉換器另包含有一飛輪二極體(wheel diode)，具有兩端，分別電耦接至該整流後直流電壓與該功率開關。 The overvoltage protection control method of claim 1, wherein the power converter comprises a series inductance, a light source load, and a power switch, the power converter The utility model further comprises a flywheel diode having two ends electrically coupled to the rectified DC voltage and the power switch.

如同申請專利範圍第1項之該過電壓保護控制方法，另包含有：提供一斜坡信號；偵測並記錄該偵測電壓之一峰值；以及依據該峰值，決定該斜坡信號之一信號斜率。 The overvoltage protection control method as claimed in claim 1 further includes: providing a ramp signal; detecting and recording a peak value of the detected voltage; and determining a signal slope of the ramp signal according to the peak value.

如同申請專利範圍第5項之該過電壓保護控制方法，另包含有：依據該斜坡信號以及一補償信號，決定一功率開關的一開啟時間。 The overvoltage protection control method of claim 5, further comprising: determining an opening time of a power switch according to the ramp signal and a compensation signal.

一種電源控制器，適用於一電源轉換器，該電源轉換器包含有一整流器，用以將一交流市電壓，整流為一整流後直流電壓，該電源控制器包含有；一波谷偵測器，用以判斷該整流後直流電壓是否位於一局部最低值；一過電壓比較器，用以比較一偵測電壓以及一過電壓參考電壓，其中，該偵測電壓可代表該整流後直流電壓；以及一邏輯電路，當該整流後直流電壓位於該局部最低值，且該偵測電壓高於該過電壓參考電壓時，用以提供一過電壓保護信號，以停止該電源轉換器之電能轉換。 A power controller is provided for a power converter, the power converter includes a rectifier for rectifying an AC voltage to a rectified DC voltage, the power controller includes; a valley detector, To determine whether the rectified DC voltage is at a local minimum value; an overvoltage comparator for comparing a detection voltage and an overvoltage reference voltage, wherein the detection voltage can represent the rectified DC voltage; and The logic circuit is configured to provide an overvoltage protection signal to stop the power conversion of the power converter when the rectified DC voltage is at the local minimum value and the detection voltage is higher than the overvoltage reference voltage.

如同申請專利範圍第7項之該電源控制器，其中，該電源轉換器包含有一降壓轉換器，其包含有一功率開關以及一電感，該波谷偵測器包含有：一波谷比較器，用以比較一電流偵測信號以及一預設值；其中，該電流偵測信號可代表流經該功率開關之一電流。 The power controller of claim 7, wherein the power converter comprises a buck converter comprising a power switch and an inductor, the valley detector comprising: a valley comparator for Comparing a current detection signal with a predetermined value; wherein the current detection signal can represent a current flowing through the power switch.

如同申請專利範圍第8項之該電源控制器，其中，該波谷偵測器另包含有：一延遲時間產生器，連接至該比較器，當該電流偵測信號持續低於該預設值一預設時間後，用以提供一確認信號，表示該整流後直流電壓位於該局部最低值。The power controller of claim 8 is as claimed in claim 8 , wherein the valley detector further comprises And a delay time generator connected to the comparator, when the current detection signal continues to be lower than the preset value for a predetermined time, to provide an acknowledgment signal, indicating that the rectified DC voltage is at the local minimum value.

一種電源轉換器，包含有：一整流器，用以將一交流市電壓，整流為一整流後直流電壓以及一接地線；以及一電源控制器，其包含有；一波谷偵測器，用以判斷該整流後直流電壓是否位於一局部最低值；以及一過電壓比較器，用以比較一偵測電壓以及一過電壓參考電壓，其中，該偵測電壓可代表該整流後直流電壓；其中，當該整流後直流電壓位於該局部最低值，且該偵測電壓高於該過電壓參考電壓時，該電源控制器停止該電源轉換器之電能轉換。A power converter includes: a rectifier for rectifying an AC voltage to a rectified DC voltage and a ground line; and a power controller including: a valley detector for determining Whether the rectified DC voltage is at a local minimum value; and an overvoltage comparator for comparing a detection voltage and an overvoltage reference voltage, wherein the detection voltage can represent the rectified DC voltage; wherein, when The rectified DC voltage is at the local minimum value, and when the detection voltage is higher than the overvoltage reference voltage, the power controller stops the power conversion of the power converter.

如同申請專利範圍第10項之該電源轉換器，包含有：一降壓轉換器，其包含有一功率開關以及一電感，串接於該整流後直流電壓以及該接地線之間；其中，該波谷偵測器包含有一波谷比較器，用以比較一電流偵測信號以及一預設值；且該電流偵測信號可代表流經該功率開關之一電流。The power converter of claim 10, comprising: a buck converter comprising a power switch and an inductor connected in series between the rectified DC voltage and the ground line; wherein the valley The detector includes a valley comparator for comparing a current detection signal with a predetermined value; and the current detection signal can represent a current flowing through the power switch.

如同申請專利範圍第10項之該電源轉換器，其中，該波谷偵測器包含有一延遲時間產生器，連接至該比較器，且當該電流偵測信號持續低於該預設值一預設時間後，該延遲時間產生器提供一確認信號，決定該整流後直流電壓位於該局部最低值。The power converter of claim 10, wherein the valley detector comprises a delay time generator connected to the comparator, and when the current detection signal continues to be lower than the After the preset value is a preset time, the delay time generator provides an acknowledgment signal to determine that the rectified DC voltage is at the local minimum value.