TWI442677B - Power supply and controller thereof - Google Patents
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本發明係指一種電源供應器之控制器及其相關電源供應器,尤指一種低成本、單一電路晶片並具有高功率因素之電源供應器之控制器及其相關電源供應器。 The present invention refers to a power supply controller and its associated power supply, and more particularly to a low cost, single circuit chip power controller with high power factor and its associated power supply.
電源供應器為電器產品中不可或缺的一部分,例如發光二極體(Light Emitting Diode,LED)照明之應用。理想的電源供應器應具有功率因素校正(Power Factor Correction,PFC)功能,以確保交流電流與電壓相位保持一致,並消除非理想之諧波,以提升功率因素。 Power supplies are an integral part of electrical products, such as Light Emitting Diode (LED) lighting applications. The ideal power supply should have Power Factor Correction (PFC) to ensure that the AC current is consistent with the voltage phase and eliminates non-ideal harmonics to increase power factor.
電源供應器應將輸出電壓、電流或電能維持在穩定的範圍內,以確保電子裝置操作之安全及效率。因此,電源供應器通常係利用來自其輸出端之一回授路徑,以將輸出電壓、電流或電能維持於特定範圍內。再者,基於安全考量,習知電源供應器通常會將一變壓器之一次側與二次側互相隔離。 The power supply should maintain the output voltage, current or power within a stable range to ensure the safety and efficiency of the operation of the electronic device. Therefore, the power supply typically utilizes a feedback path from one of its outputs to maintain the output voltage, current, or power within a particular range. Furthermore, based on safety considerations, conventional power supplies typically isolate the primary and secondary sides of a transformer from each other.
請參考第1圖,第1圖為一習知電源供應器10之示意圖。電源供應器10係一反馳式(Fly-back)交換式電源供應器(Switching Mode Power Supply,SMPS),包含有一變壓器(Transformer)100、一電 晶體102、一脈波寬度調變(Pulse Width Modulation,PWM)控制單元104、一回授控制單元106、一二極體108(作為整流功能)及一電容C1。變壓器100包含有一一次側繞組(Primary Side Winding)NP以及一二次側繞組(Secondary Side Winding)NS。回授控制單元106包含有電阻R1~R4、一電容C2、一光耦合器(Photocoupler)110及一三端並聯穩壓器(Three-terminal Shunt Regulator)112。 Please refer to FIG. 1 , which is a schematic diagram of a conventional power supply 10 . The power supply 10 is a Fly-back Switching Mode Power Supply (SMPS), and includes a transformer (Transformer) 100, a transistor 102, and a pulse width modulation (Pulse Width). Modulation, PWM) control unit 104, a feedback control unit 106, a diode 108 (as a rectification function) and a capacitor C1. The transformer 100 includes a primary side winding (N P ) and a secondary side winding (N S ). The feedback control unit 106 includes resistors R1 R R4 , a capacitor C2 , a photocoupler 110 , and a three-terminal Shunt Regulator 112 .
電源轉換器10的電源轉換功能係透過脈寬調變控制單元104控制電晶體102而實現。脈寬調變控制單元104根據一來自於該回授控制單元106之回授訊號VF,產生相對應之一控制訊號VPWM,以控制電晶體102之導通及關閉。當電晶體102導通時,電能儲存於一次側繞組NP,此時整流器108因逆向偏壓而不導通,而電源轉換器10之負載所需的電能由電容C1供應;當電晶體102關閉時,儲存於一次側繞組NP的電能傳遞至二次側繞組NS,此時整流器108導通,而電能傳遞至負載。如第1圖所示,回授訊號VF是由三端並聯穩壓器112驅動光耦合器110所產生。當電源轉換器10之一輸出電壓VOUT上升或下降時,回授訊號VF隨之改變,進而改變控制訊號VPWM的工作週期(duty cycle),以調整輸出至負載的電能,並使輸出電壓VOUT維持穩定。三端並聯穩壓器112須配合其周邊元件以達成其功能,其中電阻R1及R2用來將輸出電壓VOUT分壓以產生一參考電壓,電阻R3及電容C2用來提供三端並聯穩壓器112所需的迴路補償。 The power conversion function of the power converter 10 is realized by controlling the transistor 102 through the pulse width modulation control unit 104. The pulse width modulation control unit 104 generates a corresponding one of the control signals V PWM according to a feedback signal V F from the feedback control unit 106 to control the turning on and off of the transistor 102. When the transistor 102 is turned on, the electrical energy is stored in the primary side winding N P , at which time the rectifier 108 is not turned on due to the reverse bias, and the electrical energy required for the load of the power converter 10 is supplied by the capacitor C1; when the transistor 102 is turned off The electric energy stored in the primary side winding N P is transferred to the secondary side winding N S , at which time the rectifier 108 is turned on and the electric energy is transferred to the load. As shown in FIG. 1, the feedback signal V F is generated by the three-terminal shunt regulator 112 driving the optical coupler 110. When the output voltage V OUT of the power converter 10 rises or falls, the feedback signal V F changes accordingly, thereby changing the duty cycle of the control signal V PWM to adjust the power output to the load and make the output The voltage V OUT remains stable. The three-terminal shunt regulator 112 must be matched with its peripheral components to achieve its function, wherein resistors R1 and R2 are used to divide the output voltage V OUT to generate a reference voltage, and resistor R3 and capacitor C2 are used to provide three-terminal shunt regulation. The loop compensation required by the device 112.
然而,此種二次側回授控制機制會加大電路面積及提高功率損耗,且需使用高成本的元件以隔離該一次側與該二次側,如光耦合器及三端並聯穩壓器。再者,為配合高功率輸出應用,該電路需使用兩個獨立控制器IC,即PFC控制器及PWM控制器。如此一來,不僅會增加電路設計複雜度,更提高生產成本。 However, such a secondary feedback control mechanism increases circuit area and increases power loss, and requires high cost components to isolate the primary side from the secondary side, such as an optocoupler and a three-terminal shunt regulator. . Furthermore, to accommodate high power output applications, the circuit requires two independent controller ICs, the PFC controller and the PWM controller. As a result, not only will the circuit design complexity increase, but also the production cost.
因此,本發明之主要目的即在於提供一種低成本,單一晶片,並具有高功率因素之電源供應器。 Accordingly, it is a primary object of the present invention to provide a power supply that is low cost, single wafer, and has high power factor.
本發明揭露一種控制器,用於一電源供應器,該電源供應器包含有一二次側繞組、一一次側繞組及一輔助繞組,該輔助繞組可產生對應於該二次側繞組一輸出電流之變化的一回授訊號,該控制器包含有一功率開關,包含有一第一端耦接於該一次側繞組,一第二端,及一第三端,用來根據該第二端接收之一調變訊號,控制該第一端與該第三端之間電性連結之導通,以及由該第三端產生一電流感測訊號;一定電流區塊,用來根據該回授訊號以及該電流感測訊號,產生一第一電流訊號;以及一控制單元,用來根據該第一電流訊號、該回授訊號、該電流感測訊號及來自於該電源供應器之一電壓訊號,產生該調變訊號,以控制該功率開關。 The invention discloses a controller for a power supply, the power supply comprises a secondary winding, a primary winding and an auxiliary winding, the auxiliary winding can generate an output corresponding to the secondary winding a control signal for changing the current, the controller includes a power switch, including a first end coupled to the primary side winding, a second end, and a third end for receiving according to the second end a modulation signal, controlling the conduction of the electrical connection between the first end and the third end, and generating a current sensing signal from the third end; a certain current block, according to the feedback signal and the The current sensing signal generates a first current signal; and a control unit is configured to generate the first current signal, the feedback signal, the current sensing signal, and a voltage signal from the power supply The signal is modulated to control the power switch.
本發明另揭露一種電源供應器,包含有一變壓器,包含一二次側繞組,用來提供一二次側電流;一一次側繞組,用來提供一一次 側電流;以及一輔助繞組,用來產生對應於該二次側繞組一輸出電流之變化的一回授訊號,該二次側電流與該一次側電流之間之一比例為一定值;以及一控制器,包含一功率開關,包含有一第一端耦接於該一次側,一第二端,及一第三端,用來根據該第二端接收之一調變訊號,控制該第一端與該第三端之間電性連結之導通,以及由該第三端產生一電流感測訊號;一定電流區塊,用來根據該回授訊號以及該電流感測訊號,產生一第一電流訊號;以及一控制單元,用來根據該第一電流訊號、該回授訊號、該電流感測訊號及來自於該電源供應器之一電壓訊號,產生該調變訊號,以控制該功率開關。 The invention further discloses a power supply comprising a transformer comprising a secondary winding for providing a secondary current; a primary winding for providing a primary winding a side current; and an auxiliary winding for generating a feedback signal corresponding to a change in an output current of the secondary winding, the ratio of the secondary current to the primary current being a constant value; The controller includes a power switch, including a first end coupled to the primary side, a second end, and a third end, configured to receive a modulation signal according to the second end, and control the first end Conducting a positive connection with the third end, and generating a current sensing signal from the third end; a current block for generating a first current according to the feedback signal and the current sensing signal And a control unit configured to generate the modulation signal according to the first current signal, the feedback signal, the current sensing signal, and a voltage signal from the power supply to control the power switch.
請參考第2圖,第2圖為本發明實施例一電源供應器20之示意圖。電源供應器20係用來提供一輸出電壓Vo以及一輸出電流Io至一負載214,如複數個發光二極體。電源供應器20包含一變壓器200、一功率開關Q1、一定電流區塊206、一定電壓區塊208、一控制單元210及一電流感測電阻RS。一交流輸入電壓ACin係經一橋式整流電路222整流後,透過一分壓單元224產生一一次側電壓訊號Vi。變壓器200包含有一一次側繞組(Primary Winding)NP以及一二次側繞組(Secondary Winding)NS,分別用來提供一一次側電流IP及一二次側電流IS。其中,二次側電流IS與一次側電流IP之一比例為一定值。變壓器200更包含一輔助繞組(Auxiliary Winding)NA,可透過一回授節點AUX產生對應於該二次側繞組一輸出電流Io之變化的一回授訊號VFB。輔助繞組NA係電感耦合至一次側繞組 NP及二次側繞組NS,使得輔助繞組NA上之一電感電流IL可映射至二次側繞組NS上之二次側電流之變化。如此一來,自節點AUX產生之回授訊號VFB係對應於輸出電流Io之變化。由於回授訊號VFB係來自電源供應器20之一次側,故此種回授機制被稱為一次側回授控制架構。一次側回授控制相較於二次側回授控制之一優勢為不需使用高成本元件,如光耦合器,並降低生產成本。 Please refer to FIG. 2, which is a schematic diagram of a power supply 20 according to an embodiment of the present invention. The power supply 20 is used to provide an output voltage V o and an output current I o to a load 214, such as a plurality of light emitting diodes. The power supply 20 includes a transformer 200, a power switch Q1, a constant current block 206, a certain voltage block 208, a control unit 210, and a current sensing resistor R S . An AC input voltage ACin line after a bridge rectifier circuit 222 rectifies 224 generates a primary-side voltage signal V i transmitted through a voltage divider. The transformer 200 includes a primary winding (N P ) and a secondary winding (N S ) for providing a primary side current I P and a secondary side current I S , respectively . Among them, the ratio of the secondary side current I S to the primary side current I P is a constant value. The transformer 200 further includes an auxiliary winding (N A ), and a feedback signal V FB corresponding to the change of the output current I o of the secondary winding can be generated through a feedback node AUX. The auxiliary winding N A is inductively coupled to the primary side winding N P and the secondary side winding N S such that one of the inductor currents I L on the auxiliary winding N A can be mapped to the secondary side current change on the secondary side winding N S . As a result, the feedback signal V FB generated from the node AUX corresponds to the change of the output current I o . Since the feedback signal V FB is from the primary side of the power supply 20, this feedback mechanism is called a primary side feedback control architecture. One of the advantages of primary-side feedback control over secondary-side feedback control is that it does not require the use of high-cost components, such as optocouplers, and reduces production costs.
功率開關Q1係用來根據一接收到之調變訊號VMod,導通或切斷一次側繞組NP上之一次側電流IP。功率開關Q1切斷時,一次側電流IP降至零,且電能轉移至二次側。當功率開關Q1導通時,一次側電流IP流過電流感測電阻RS,並產生一對應於一次側電流IP之電流感測訊號CS。較佳地,功率開關Q1可為一N型金屬氧化半導體(N type Metal-Oxide-Semiconductor,NMOS),其汲極耦接於變壓器200之一次側繞組NP(即電源供應器20之一次側),閘極耦接於控制單元210,以接收調變訊號VMod,以及源極耦接於電流感測電阻RS,以產生電流感測訊號CS。 The power switch Q1 is used to turn on or off the primary side current I P on the primary side winding N P according to a received modulation signal V Mod . When the power switch Q1 is turned off, the primary side current I P falls to zero, and the electric energy is transferred to the secondary side. When the power switch Q1 is turned on, the primary side current I P flows through the current sensing resistor R S and generates a current sensing signal CS corresponding to the primary side current I P . Preferably, the power switch Q1 can be an N-type metal-oxide-semiconductor (NMOS), and the drain is coupled to the primary winding N P of the transformer 200 (ie, the primary side of the power supply 20). The gate is coupled to the control unit 210 to receive the modulation signal V Mod , and the source is coupled to the current sensing resistor R S to generate the current sensing signal CS.
因此,藉由控制功率開關Q1之導通或切斷,可控制由電源供應器20之一次側傳送至二次側之電能,進而控制其輸出功率。調變訊號VMod較佳地為一脈波寬度調變訊號,用來導通或切斷功率開關Q1,藉此調控輸出電流Io。任意其他可控制功率開關Q1之導通/切斷狀態之訊號皆適用於本發明之電源供應器20。詳細而言,控制單元210係透過變更脈波寬度調變訊號VMod之工作週期(duty cycle), 以決定變壓器200之一次側繞組NP傳遞至二次側繞組NS之能量大小,並進一步地控制輸出電流Io。 Therefore, by controlling the on or off of the power switch Q1, the power transmitted from the primary side of the power supply 20 to the secondary side can be controlled, thereby controlling its output power. The modulation signal V Mod is preferably a pulse width modulation signal for turning on or off the power switch Q1, thereby regulating the output current I o . Any other signal that can control the on/off state of the power switch Q1 is applicable to the power supply 20 of the present invention. In detail, the control unit 210 determines the energy of the primary side winding N P of the transformer 200 to the secondary side winding N S by changing the duty cycle of the pulse width modulation signal V Mod and further Ground control output current I o .
當調變訊號VMod由一低電位轉換至一高電位時,功率開關Q1導通,通過一次側繞組NP以及電流感測電阻RS之一次側電流IP漸增。電流感測電阻RS感應到一次側電流IP,因此產生電流感測訊號CS至定電流區塊206。輸入電壓ACin產生之電能儲存於一次側繞組NP,此時二次側之一整流器226以及一次側之一二極體216因逆向偏壓而不導通,故通過二次側繞組NS的電流IS為零。當調變訊號VMod使功率開關Q1被切斷時,儲存於一次側繞組NP的電能傳遞至二次側繞組NS,導致通過二次側繞組NS的電流IS增加。由於輔助繞組NA之能夠映射IS之變化,因此電感電流IL亦同步增加。 When the modulation signal V Mod is switched from a low potential to a high potential, the power switch Q1 is turned on, and the primary side current I P through the primary side winding N P and the current sensing resistor R S is gradually increased. The current sense resistor R S senses the primary side current I P , thus generating a current sense signal CS to the constant current block 206. The electric energy generated by the input voltage ACin is stored in the primary side winding N P , and at this time, one of the secondary side rectifier 226 and one of the primary side diodes 216 are not turned on due to the reverse bias, so the current passing through the secondary side winding N S I S is zero. When the modulation signal V Mod causes the power switch Q1 to be turned off, the electric energy stored in the primary side winding N P is transmitted to the secondary side winding N S , resulting in an increase in the current I S passing through the secondary side winding N S . Since the auxiliary winding N A can map the change of I S , the inductor current I L also increases synchronously.
請參考第3圖,第3圖為本發明實施例第2圖中定電流區塊206之示意圖。定電流區塊206包含一波形偵測單元302、一運算單元304、一誤差放大器306以及一比較單元308。波形偵測單元302係耦接於電流感測電阻RS,並用來偵測電流感測訊號CS之一波形,以產生一擷取訊號VP。波形偵測單元302係偵測電流感測電阻RS上之一次側電流IP,以取得電流感測訊號CS之波形。 Please refer to FIG. 3, which is a schematic diagram of a constant current block 206 according to a second embodiment of the present invention. The constant current block 206 includes a waveform detecting unit 302, an arithmetic unit 304, an error amplifier 306, and a comparing unit 308. The waveform detecting unit 302 is coupled to the current sensing resistor R S and used to detect a waveform of the current sensing signal CS to generate a capture signal V P . The waveform detecting unit 302 detects the primary side current I P on the current sensing resistor R S to obtain the waveform of the current sensing signal CS.
運算單元304耦接於波形偵測單元302,並用來分壓擷取訊號VP,以產生一選擇電壓VX。運算單元304係用來偵測回授訊號VFB之一放電週期Tdis(即二次側繞組NS上之二次側電流IS遞減至零之
一放電週期)與回授訊號VFB之一週期T,並產生一時間因子Tf。時間因子Tf可表示為[(Td係/T)*K],其中K為一常數。運算單元304根據時間因子Tf及擷取訊號VP,產生選擇電壓VX。選擇電壓VX係擷取訊號VP之一分壓結果,可表示為:
選擇電壓VX係正比於電源供應器20之輸出電流Io,其推導細節可由中華民國專利申請號099123938(與本發明相同申請者及發明人)而知,選擇電壓VX可表示為:
也就是說,定電流區塊206可根據波形偵測單元302及運算單元304,得到正比於輸出電流Io之選擇電壓VX。簡單來說,輸出電流Io係受到選擇電壓VX所控制。 That is to say, the constant current block 206 can obtain the selection voltage V X proportional to the output current I o according to the waveform detecting unit 302 and the arithmetic unit 304. Briefly, the output current I o line selection voltage V X by the control.
誤差放大器306包含有兩輸入端,分別耦接於選擇電壓VX及一參考電壓Vref4,其可將選擇電壓VX之一最大值限制於第四參考電壓Vref4之內。如此一來,輸出電流Io之一最大輸出電流IoMAX可被限制至相關於第四參考電壓Vref4之一穩定值。根據中華民國專利申請號099123938,可進一步推得IoMAX可表示為。如此一來,若電源供應器20之輸出電壓Vo超過一可容忍電壓,輸出電流Io可被限制至固定值,以保護電源供應器20之電路不至於損壞。除 此之外,穩定輸出電流Io可應用於相關的定電流電路,如發光二極體照明等。 The error amplifier 306 includes two input terminals respectively coupled to the selection voltage V X and a reference voltage V ref4 , which can limit the maximum value of one of the selection voltages V X to the fourth reference voltage V ref4 . Thus, one of the output current I o I oMAX maximum output current may be limited to a stable value associated with one of the fourth reference voltage ref4 V. According to the Republic of China patent application number 099123938, it can be further derived that I oMAX can be expressed as . Thus, if the power supply voltage V o the output 20 of more than tolerable voltage, output current I o can be limited to a fixed value, to protect the circuit of the power supply 20 will not be damaged. In addition, the stable output current I o can be applied to related constant current circuits, such as LED illumination.
比較單元308係用來比較由誤差放大器306輸出之一第一比較訊號COMPI與一第一參考電壓Vref1,並產生第一電流訊號Ii至控制單元210。而一電壓儲存單元312係用來儲存誤差放大器306輸出之第一比較訊號COMPI。一比較器310係用來將一第一開關SW1導通或切斷,以產生第一電流訊號Ii。比較器310包含有一第一正輸入端耦接於第一比較訊號COMPI,一第二正輸入端耦接於第一參考電壓Vref1,以及一負輸入端耦接於一第一節點A。當兩個正輸入端其中之一的電壓高於負輸入端時(即當第一比較訊號COMPI或第一參考電壓Vref1其中之一高於第一節點A之電壓時),比較器310輸出一高準位電壓,以將第一開關SW1導通。當第一開關SW1被導通時,一電流源C1將第一電流訊號Ii輸出至控制單元210。一電阻(作為一負載)係耦接於第一節點A以及一接地端之間,且當來自於電流源C1之電流流過負載時,第一節點A之電壓隨即升高。當第一節點A之電壓以及比較器310之負輸入端高於兩正輸入端之電壓時,比較器310輸出一低電壓準位,以將第一開關SW1切斷。第一開關SW1為一三端元件,且較佳地可為一N型金屬氧化物半導體場效電晶體(N-type MOSFET),其汲極耦接於電流源C1,閘極耦接於比較器310,以及源極耦接於第一節點A。 The comparing unit 308 is configured to compare one of the first comparison signal COMPI and the first reference voltage V ref1 outputted by the error amplifier 306, and generate the first current signal I i to the control unit 210. A voltage storage unit 312 is used to store the first comparison signal COMPI output by the error amplifier 306. A comparator 310 is used to turn on or off a first switch SW1 to generate a first current signal I i . The comparator 310 includes a first positive input coupled to the first comparison signal COMPI, a second positive input coupled to the first reference voltage V ref1 , and a negative input coupled to the first node A. When the voltage of one of the two positive input terminals is higher than the negative input terminal (ie, when one of the first comparison signal COMPI or the first reference voltage V ref1 is higher than the voltage of the first node A), the comparator 310 outputs A high level voltage is applied to turn on the first switch SW1. When the first switch SW1 is turned on, a current source C1 outputs the first current signal I i to the control unit 210. A resistor (as a load) is coupled between the first node A and a ground, and when a current from the current source C1 flows through the load, the voltage of the first node A increases. When the voltage of the first node A and the negative input of the comparator 310 are higher than the voltages of the two positive inputs, the comparator 310 outputs a low voltage level to turn off the first switch SW1. The first switch SW1 is a three-terminal component, and is preferably an N-type MOSFET. The drain is coupled to the current source C1, and the gate is coupled to the comparator. The device 310 and the source are coupled to the first node A.
至於運算單元304之實現方法,對本領域具通常知識者可進一 步參考中華民國專利申請號099123938,(與本發明相同申請及發明人)其係利用一計數器以及多個開關,以實現運算單元304。因此,本發明可不必利用複雜或昂貴的元件(例如積分器),即可實現定電流區塊206,進而降低電源供應器20之生產成本。 As for the implementation method of the operation unit 304, it is possible to have a general knowledge in the field. Referring to the Republic of China Patent Application No. 099123938, (the same application and inventor as the present invention) utilizes a counter and a plurality of switches to implement the arithmetic unit 304. Therefore, the present invention can realize the constant current block 206 without using complicated or expensive components (for example, integrators), thereby reducing the production cost of the power supply 20.
電源供應器20可選擇性地包含一定電壓區塊208,以提供電路過電壓保護機制(Over-voltage protection)。對本領域具通常知識者可進一步參考中華民國專利申請號099125126(與本發明相同申請者及發明人)中定電壓區塊208之實現方法。請參考第4圖,第4圖為定電壓區塊208之示意圖。定電壓區塊208可根據回授訊號VFB之一膝點電壓(即通過二次側繞組NS之電流IS降為零時,輔助繞組NA上之一電壓),產生一第二電流訊號,並包含有一波峰偵測單元402,用來根據回授訊號VFB之一膝點電壓,產生一峰值電壓訊號Ve。波峰偵測單元402係由一電壓追蹤單元414及一取樣保持單元416所組成;電壓追蹤單元414用來追踪回授訊號VFB,以輸出一第一電壓訊號Vtr及一第一控制訊號Vde;取樣保持單元416耦接於電壓追蹤單元414,用來取樣第一電壓訊號Vtr,以產生峰值電壓訊號Ve。 Power supply 20 can optionally include a voltage block 208 to provide circuit over-voltage protection. A method for realizing the voltage block 208 in the Republic of China Patent Application No. 099125126 (the same applicant and inventor of the present invention) can be further referred to by those having ordinary knowledge in the art. Please refer to FIG. 4, which is a schematic diagram of the constant voltage block 208. The constant voltage block 208 can generate a second current according to one knee voltage of the feedback signal V FB (ie, a voltage on the auxiliary winding N A when the current I S of the secondary winding N S drops to zero) The signal includes a peak detecting unit 402 for generating a peak voltage signal V e according to a knee voltage of the feedback signal V FB . The peak detecting unit 402 is composed of a voltage tracking unit 414 and a sample holding unit 416. The voltage tracking unit 414 is configured to track the feedback signal V FB to output a first voltage signal V tr and a first control signal V. The sample holding unit 416 is coupled to the voltage tracking unit 414 for sampling the first voltage signal V tr to generate a peak voltage signal V e .
簡單來說,當流經二次側繞組NS之電流遞減至零時,回授訊號VFB上產生之一膝點電壓係被電壓追蹤單元414追踪。取樣保持單元416對電壓追蹤單元414之膝點電壓取樣,並產生一峰值電壓訊號Ve。定電壓區塊亦產生一相對應之第二電流訊號Iv,使控制單 元210產生調變訊號VMod,以控制功率開關之導通或切斷,進而控制電源供應器20之轉換功率。因此,當電源供應器20之負載產生變化,並造成輸出電壓Vo變動時(例如當負載214之一發光二極體燒毀或短路),回授訊號VFB之膝點電壓亦對應變化。接著,波峰偵測單元402產生對應於回授訊號VFB之膝點電壓的一峰值電壓訊號Ve,進而使控制單元210根據回授訊號VFB,產生具有適當工作週期之一調變訊號VMod。控制訊號VMod係用來控制電晶體204,並調節傳遞至二次側之不同供電功率,以供電至不同的負載使用。誤差放大器406及比較單元408之運作類似於定電流區塊206,故不在此贅述。 Briefly, when the current flowing through the secondary side winding N S is decremented to zero, one of the knee point voltages generated on the feedback signal V FB is tracked by the voltage tracking unit 414. The sample hold unit 416 samples the knee point voltage of the voltage tracking unit 414 and generates a peak voltage signal V e . The constant voltage block also generates a corresponding second current signal I v , so that the control unit 210 generates the modulation signal V Mod to control the power switch to be turned on or off, thereby controlling the conversion power of the power supply 20 . Therefore, when the load of the power supply 20 changes and causes the output voltage Vo to fluctuate (for example, when one of the LEDs of the load 214 is burned or short-circuited), the knee voltage of the feedback signal V FB also changes accordingly. Subsequently, the peak detecting unit 402 generates corresponding to the knee voltage of the feedback signal V FB is a peak of the signal voltage V E, thereby enabling the control unit 210 according to the feedback signal V FB, generating an appropriate one of the modulation signal having a duty cycle V Mod . The control signal V Mod is used to control the transistor 204 and regulate the different power supplies delivered to the secondary side for power supply to different loads. The operation of error amplifier 406 and comparison unit 408 is similar to constant current block 206 and will not be described herein.
請參考第5圖,第5圖為第2圖中電源供應器20之控制單元210之一實施例示意圖。控制單元210包含一設置單元502、一重置單元504及一SR正反器506。設置單元502用來產生一設置訊號Vset,重置單元504用來產生一重置訊號Vreset,而SR正反器506則根據設置訊號Vset以及重置訊號Vreset,產生調變訊號VMod。 Please refer to FIG. 5, which is a schematic diagram of an embodiment of the control unit 210 of the power supply 20 in FIG. The control unit 210 includes a setting unit 502, a reset unit 504, and an SR flip-flop 506. The setting unit 502 is configured to generate a setting signal V set , the reset unit 504 is configured to generate a reset signal V reset , and the SR flip-flop 506 generates the modulation signal V according to the setting signal V set and the reset signal V reset . Mod .
設置單元502包含一零電流偵測器518,用於偵測回授訊號VFB中之一零電流,並產生設置訊號Vset。詳細而言,當輔助繞組NA之一電感電流IL遞減至零時,零電流偵測器518偵測到一零電流,並輸出設置訊號Vset至SR正反器506。而SR正反器506進一步將調變訊號VMod設為一高電壓準位「1」,以導通功率開關Q1。 The setting unit 502 includes a zero current detector 518 for detecting one of the zero currents of the feedback signal V FB and generating the setting signal V set . In detail, when the inductor current I L of the auxiliary winding N A is decremented to zero, the zero current detector 518 detects a zero current and outputs the set signal V set to the SR flip-flop 506. The SR flip-flop 506 further sets the modulation signal V Mod to a high voltage level "1" to turn on the power switch Q1.
重置單元504包含一電流相加單元508、一輸入電壓單元510、一誤差放大器512、一乘法器514以及一比較器516。電流相加單元508分別將來自於定電流區塊206及定電壓區塊208之第一電流訊號Ii及第二電流訊號Iv相加,而產生一電流總和Isum。輸入電壓單元510則根據電流總和Isum,產生一反相電壓訊號Vinv。誤差放大器512可限制反相電壓訊號Vinv不超過第一參考電壓Vref1,並產生一比較訊號COMP。乘法器514則對比較訊號COMP與來自於電源供應器20之電壓訊號Vi進行乘法運算,並產生一電壓乘積Vm。比較器516係比較電壓乘積Vm與電流感測訊號CS,並產生重置訊號Vreset。詳細而言,一旦功率開關Q1導通,一次側電流IP上升,而導致功率開關Q1源極之電流感測電阻Rs的電壓亦隨即上升。誤差放大器512係比較參考電壓Vref1與反相電壓訊號Vinv(其對應來自定電流區塊206之第一電流訊號Ii與來自於定電壓區塊208之第二電流訊號Iv之電流總和Isum),並產生比較訊號COMP。接著,乘法器514對比較訊號COMP與分壓自電源供應器20輸入電壓之一次電壓訊號Vi(對應於電源供應器20經整流後之直流輸入電壓)進行相乘運算,並產生一電壓乘積Vm。接著,比較器516比較電壓乘積Vm與電流感測訊號CS。若電流訊號CS高於電壓乘積Vm,則比較器516輸出重置訊號Vreset至SR正反器506,以產生一低電壓準位之調變訊號VMod,進而將功率開關Q1切斷。第6B圖為電壓乘積Vm及電流感測訊號CS經比較後,產生調變訊號VMod之示意圖。 The reset unit 504 includes a current adding unit 508, an input voltage unit 510, an error amplifier 512, a multiplier 514, and a comparator 516. The current summing unit 508 adds the first current signal I i and the second current signal I v from the constant current block 206 and the constant voltage block 208 to generate a current sum I sum . The input voltage unit 510 generates an inverted voltage signal V inv according to the current sum I sum . The error amplifier 512 can limit the inverted voltage signal V inv not to exceed the first reference voltage V ref1 and generate a comparison signal COMP. The multiplier 514 pairs of signal COMP to compare the power supply from the voltage signal V i 20 of the multiplication, and generating a voltage product V m. The comparator 516 compares the voltage product V m with the current sense signal CS and generates a reset signal V reset . In detail, once the power switch Q1 is turned on, the primary side current I P rises, and the voltage of the current sense resistor R s of the source of the power switch Q1 also rises. The error amplifier 512 compares the reference voltage V ref1 with the inverted voltage signal V inv (which corresponds to the sum of the current from the first current signal I i of the constant current block 206 and the second current signal I v from the constant voltage block 208 I sum ) and generate a comparison signal COMP. Next, the multiplier 514 multiplies the comparison signal COMP with a primary voltage signal V i (corresponding to the rectified DC input voltage of the power supply 20) that divides the input voltage from the power supply 20, and generates a voltage product. V m . Next, the comparator 516 compares the voltage product V m with the current sense signal CS. If the current signal CS is higher than the voltage product V m , the comparator 516 outputs the reset signal V reset to the SR flip-flop 506 to generate a low voltage level modulation signal V Mod , thereby cutting the power switch Q1. FIG. 6B is a schematic diagram of the voltage modulation product V m and the current sensing signal CS being compared to generate a modulation signal V Mod .
簡單來說,藉由根據調變訊號VMod,交替設置或重置SR正反 器506,以將功率開關Q1導通或切斷,一次側電流IP之平均電流Ip_avg的波形將隨著直流輸入電壓Vi之波形變動,使一次側電流IP及直流輸入電壓Vi之間達到同相位,因此可得到高功率因素,並提高電能轉換效率。如第6A圖所示,第6A圖為電源供應器20之相關訊號波形示意圖。在第6A圖中,電感電流於調變訊號VMod位於高電壓準位時上升,並且達到一由電壓乘積Vm所決定之峰值電感電流。當功率開關Q1被切斷時,電感電流隨即下降。電感電流之一零電流會致使功率開關Q1再度導通,故可得到波形與Vm同相位之一平均輸入電流Ip_avg。因此,平均輸入電流Ip_avg與輸入電壓Vi亦同相位,故電源供應器20具有高功率因素。控制單元210亦可在第一電流訊號Ii(對應於輸出電流Io)或第二電流訊號Iv(對應於輸出電壓Vo)過高時,切斷功率開關Q1,故電源供應器20可提供穩定輸出電流及輸出電壓。因此,電源供應器20可用於各種定電流應用,例如發光二極體光源等。再者,電源供應器20具有過電壓保護機制,故可輸出不同輸出功率至不同的負載。請參考第7圖,第7圖為本發明實施例電源供應器20之輸出電壓Vo對輸出電流Io之示意圖。在第7圖中,當輸出電壓Vo介於Vf到0時,輸出電流Io則逐漸下降。當輸出電壓Vo落於Vf至nVf之間時,輸出電流Io會被控制在一穩定電流值I1。較佳地,電壓Vf可為一發光二極體照明電路中,單個發光二極體之輸出電壓Vo的一可容忍準位,而nVf則為n個發光二極體串聯時之一輸出電壓。當輸出電壓Vo超過電壓Vf時,則電源供應器之輸出電流Io係被限制於一穩定電流值I1。如此一來,將可避免電源供應器輸出過高功率且損壞內部或外 部電路。 Briefly, by alternately setting or resetting the SR flip-flop 506 according to the modulation signal V Mod to turn the power switch Q1 on or off, the waveform of the average current I p_avg of the primary side current I P will follow the direct current. input voltage V i of the fluctuation waveform, the primary-side current I P reaches and DC input voltage V i between the phase, and therefore to obtain a high power factor, and improve power conversion efficiency. As shown in FIG. 6A, FIG. 6A is a schematic diagram of related signal waveforms of the power supply 20. In Figure 6A, the inductor current rises when the modulation signal V Mod is at the high voltage level and reaches a peak inductor current determined by the voltage product V m . When the power switch Q1 is turned off, the inductor current drops. One of the inductor currents, zero current, causes the power switch Q1 to turn on again, so that the average input current I p_avg of the waveform and the same phase of V m can be obtained. Therefore, the average input current I p_avg is also in phase with the input voltage V i , so the power supply 20 has a high power factor. The control unit 210 can also cut off the power switch Q1 when the first current signal I i (corresponding to the output current I o ) or the second current signal I v (corresponding to the output voltage V o ) is too high, so the power supply 20 Provides stable output current and output voltage. Thus, the power supply 20 can be used in a variety of constant current applications, such as light emitting diode sources and the like. Moreover, the power supply 20 has an overvoltage protection mechanism, so that different output powers can be output to different loads. Please refer to FIG. 7, for example, the power supply output voltage V o 20 a schematic diagram of an output current I o of a seventh embodiment of the present invention graph. In Fig. 7, when the output voltage V o is between V f and 0, the output current I o gradually decreases. When the output voltage Vo falls between V f and nV f , the output current I o is controlled to a constant current value I1. Preferably, the voltage Vf is a tolerable level of the output voltage V o of the single light-emitting diode in a light-emitting diode lighting circuit, and nV f is one output when the n light-emitting diodes are connected in series. Voltage. When the output voltage V o exceeds the voltage V f , the output current I o of the power supply is limited to a stable current value I1 . As a result, it is possible to prevent the power supply from outputting excessive power and damaging internal or external circuits.
因此,當輸出電壓VO超過一可容忍準位時,電源供應器20可提供穩定的輸出電流IOMax,以供需要定電流之相關應用,並避免輸出電流過大而造成電源供應器20損壞。簡言之,定電流區塊可透過波形偵測單元302以及運算單元304,求得與輸出電流Io成正比之選擇電壓VX,並將選擇電壓VX限制在參考電壓Vref4,使得最大輸出電流IOMax被限制在一定值,以供定電流之相關應用。 Therefore, when the output voltage V O exceeds a tolerable level, the power supply 20 can provide a stable output current I OMax for related applications requiring a constant current and avoid excessive damage of the power supply 20 due to excessive output current. In short, the constant current block can pass through the waveform detecting unit 302 and the arithmetic unit 304 to obtain the selection voltage V X proportional to the output current I o and limit the selection voltage V X to the reference voltage V ref4 so that the maximum The output current I OMax is limited to a certain value for the application of the constant current.
綜上所述,本發明可達到一具有高功率因素之電源供應器,並可透過一次側回授機制以避免使用昂貴且複雜元件(如以光耦合器達到電源供應器一次及二次側隔離),進而降低成本。同時,本發明可透過定電流區塊及定電壓區塊,提供輸出功率之調節,且不需使用複雜或昂貴的電路元件(例如積分器、三端並聯穩壓器等)。再者,根據本發明,功率因素校正、脈波寬度調變(PWM)以及功率調節控制等功能皆可利用單一電路晶片實現,因此可縮小電路面積,降低不必要之功率消耗,且降低製造成本。 In summary, the present invention can achieve a power supply with high power factor, and can pass through the primary side feedback mechanism to avoid the use of expensive and complex components (such as optical coupler to achieve primary and secondary side isolation of the power supply) ), thereby reducing costs. At the same time, the present invention can provide adjustment of output power through constant current blocks and constant voltage blocks without using complex or expensive circuit components (such as integrators, three-terminal shunt regulators, etc.). Furthermore, according to the present invention, functions such as power factor correction, pulse width modulation (PWM), and power adjustment control can be realized by a single circuit chip, thereby reducing circuit area, reducing unnecessary power consumption, and reducing manufacturing 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.
10、20‧‧‧電源供應器 10, 20‧‧‧Power supply
100、102‧‧‧變壓器 100, 102‧‧‧ transformer
104‧‧‧脈波寬度調變控制單元 104‧‧‧ Pulse width modulation control unit
106‧‧‧回授控制單元 106‧‧‧Responsible control unit
110‧‧‧光耦合器 110‧‧‧Optocoupler
112‧‧‧三端並聯穩壓器 112‧‧‧Three-terminal shunt regulator
200‧‧‧變壓器 200‧‧‧Transformer
204‧‧‧電晶體 204‧‧‧Optoelectronics
206‧‧‧定電流區塊 206‧‧‧Constant current block
208‧‧‧定電壓區塊 208‧‧ ‧ constant voltage block
210‧‧‧控制單元 210‧‧‧Control unit
214‧‧‧負載 214‧‧‧ load
216‧‧‧二極體 216‧‧ ‧ diode
222‧‧‧橋式整流電路 222‧‧‧Bridge rectifier circuit
224‧‧‧分壓單元 224‧‧ ‧pressure unit
226‧‧‧整流器 226‧‧‧Rectifier
302‧‧‧波形偵測單元 302‧‧‧ Waveform detection unit
304‧‧‧運算單元 304‧‧‧ arithmetic unit
306、406、512‧‧‧誤差放大器 306, 406, 512‧‧‧ error amplifier
308、408‧‧‧比較單元 308, 408‧‧‧ comparison unit
310、410、516‧‧‧比較器 310, 410, 516‧‧‧ comparator
402‧‧‧波峰偵測單元 402‧‧‧Crest detection unit
414‧‧‧電壓追蹤單元 414‧‧‧Voltage tracking unit
416‧‧‧取樣保持單元 416‧‧‧Sampling unit
502‧‧‧設置單元 502‧‧‧Setting unit
504‧‧‧重置單元 504‧‧‧Reset unit
506‧‧‧SR正反器 506‧‧‧SR positive and negative
508‧‧‧電流相加單元 508‧‧‧current summing unit
510‧‧‧輸入電壓單元 510‧‧‧Input voltage unit
514‧‧‧乘法器 514‧‧‧Multiplier
518‧‧‧零電流偵測器 518‧‧‧ zero current detector
VFB‧‧‧回授訊號 V FB ‧‧‧Response signal
CS‧‧‧電流感測訊號 CS‧‧‧current sensing signal
NP‧‧‧一次側繞組 N P ‧‧‧ primary winding
NS‧‧‧二次側繞組 N S ‧‧‧secondary winding
NA‧‧‧輔助繞組 N A ‧‧‧Auxiliary winding
Vo‧‧‧輸出電壓 V o ‧‧‧output voltage
Io‧‧‧輸出電流 I o ‧‧‧Output current
VMod‧‧‧調變訊號 V Mod ‧‧‧ modulated signal
Vset‧‧‧設置訊號 V set ‧‧‧Set signal
Vreset‧‧‧重置訊號 V reset ‧‧‧Reset signal
Vm‧‧‧電壓乘積 V m ‧‧‧voltage product
Isum‧‧‧電流總和 I sum ‧‧‧current sum
第1圖為一習知電源供應器之示意圖。 Figure 1 is a schematic diagram of a conventional power supply.
第2圖為本發明實施例一電源供應器之示意圖。 FIG. 2 is a schematic diagram of a power supply according to an embodiment of the present invention.
第3圖為本發明實施例第2圖中定電流區塊之示意圖。 Fig. 3 is a schematic view showing a constant current block in Fig. 2 of the embodiment of the invention.
第4圖為本發明實施例第2圖中定電壓區塊之示意圖。 Figure 4 is a schematic diagram of a constant voltage block in Figure 2 of the embodiment of the present invention.
第5圖為本發明實施例第2圖中控制單元之示意圖。 Figure 5 is a schematic diagram of a control unit in Figure 2 of the embodiment of the present invention.
第6A、6B圖為本發明實施例第2圖中電源供應器之波形之示意圖。 6A and 6B are schematic views showing waveforms of a power supply device in Fig. 2 of the embodiment of the present invention.
第7圖為本發明實施例電源供應器之輸出電壓對輸出電流之示意圖。 Figure 7 is a schematic diagram showing the output voltage versus output current of the power supply of the embodiment of the present invention.
20‧‧‧電源供應器 20‧‧‧Power supply
200‧‧‧變壓器 200‧‧‧Transformer
204‧‧‧電晶體 204‧‧‧Optoelectronics
206‧‧‧定電流區塊 206‧‧‧Constant current block
208‧‧‧定電壓區塊 208‧‧ ‧ constant voltage block
210‧‧‧控制單元 210‧‧‧Control unit
214‧‧‧負載 214‧‧‧ load
216‧‧‧二極體 216‧‧ ‧ diode
222‧‧‧橋式整流電路 222‧‧‧Bridge rectifier circuit
224‧‧‧分壓單元 224‧‧ ‧pressure unit
226‧‧‧整流器 226‧‧‧Rectifier
VFB‧‧‧回授訊號 V FB ‧‧‧Response signal
CS‧‧‧電流感測訊號 CS‧‧‧current sensing signal
NP‧‧‧一次側繞組 N P ‧‧‧ primary winding
NS‧‧‧二次側繞組 N S ‧‧‧secondary winding
NA‧‧‧輔助繞組 N A ‧‧‧Auxiliary winding
Vo‧‧‧輸出電壓 V o ‧‧‧output voltage
Io‧‧‧輸出電流 I o ‧‧‧Output current
VMod‧‧‧調變訊號 V Mod ‧‧‧ modulated signal
Claims (32)
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TW100118912A TWI442677B (en) | 2011-05-30 | 2011-05-30 | Power supply and controller thereof |
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TW100118912A TWI442677B (en) | 2011-05-30 | 2011-05-30 | Power supply and controller thereof |
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TWI442677B true TWI442677B (en) | 2014-06-21 |
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TWI551016B (en) * | 2016-01-21 | 2016-09-21 | Power supply and power supply method | |
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US9660539B2 (en) | 2015-01-30 | 2017-05-23 | 02Micro Inc. | Switching power supplies, and switch controllers for switching power supplies |
TWI589106B (en) * | 2015-01-30 | 2017-06-21 | 凹凸科技國際股份有限公司 | Switching power supplies and switch controllers |
TWI581535B (en) * | 2016-01-19 | 2017-05-01 | 群光電能科技股份有限公司 | Over voltage protection circuit |
TWI551016B (en) * | 2016-01-21 | 2016-09-21 | Power supply and power supply method |
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