TWI481141B - And a system and method for protecting a power supply conversion system based at least on a feedback signal - Google Patents

Description

System and method for protecting a power conversion system based on at least a feedback signal

The present invention relates to an integrated circuit. More specifically, the present invention provides systems and methods for protecting a power conversion system based on at least a feedback signal. Merely by way of example, the invention has been applied to a flyback power conversion system. However, it will be appreciated that the invention has a broader range of applications.

In general, conventional power conversion systems typically use a transformer to isolate the input voltage on the primary side and the output voltage on the secondary side. To adjust the output voltage, certain components such as TL431 and optocouplers can be used to transmit the feedback signal from the secondary side to the controller wafer on the primary side. Alternatively, the output voltage on the secondary side can be mirrored to the primary side, so the output voltage is controlled by directly adjusting some parameters on the primary side. Thus, certain components such as TL431 and optocouplers can be omitted to reduce system cost.

Figure 1 is a simplified diagram showing a conventional flyback power conversion system with primary side sensing and adjustment. The power conversion system 100 includes a primary winding 110, a secondary winding 112, an auxiliary winding 114, a power switch 120, a current sensing resistor 130, an equivalent resistor 140 of an output cable, resistors 150 and 152, and a rectifier diode 160. . For example, the power switch 120 is a bipolar junction transistor. In another example, power switch 120 is a MOS transistor.

In order to adjust the output voltage within a predetermined range, it is often necessary to extract information related to the output voltage and the output load. For example, when the power conversion system 100 is operating in a discontinuous conduction mode (DCM), such information can be extracted by the auxiliary winding 114. When the power switch 120 is turned on, energy is stored in the secondary winding 112. Then, when the power switch 120 is turned off, the stored energy is released to the output terminal during the demagnetization process. The voltage of the auxiliary winding 114 maps the output voltage on the secondary side as shown below.

Where V _FB represents the voltage at node 154 and V _aux represents the voltage of auxiliary winding 114. R ₁ and R ₂ represent the resistance values of the resistors 150 and 152, respectively. In addition, n represents the turns ratio between the auxiliary winding 114 and the secondary winding 112. Specifically, n is equal to the number of turns of the auxiliary winding 114 divided by the number of turns of the secondary winding 112. The output voltage V _o and the output current I _o are respectively indicated. Further, V _F represents the forward voltage of the rectifying diode 160, and _Req represents the resistance value of the equivalent resistor 140. In addition, k represents the feedback coefficient as follows:

FIG. 2 is a simplified diagram showing the conventional operational mechanism of the flyback power conversion system 100. As shown in FIG. 2, the controller wafer of the power conversion system 100 uses a sample and hold mechanism. When the demagnetization process on the secondary side is almost completed and the secondary current 112 becomes almost zero, the voltage V _aux auxiliary winding 114 is sampled at, for example, at point A in FIG. 2. The sampled voltage value is typically held until the next voltage sample is executed. Through the negative feedback loop, the sampled voltage value can be changed to be equal to the reference voltage V _ref . Therefore, V _FB = V _ref (Equation 3)

Combine Equation 1 and Equation 3 to obtain the following formula: Based on Equation 4, the output voltage decreases as the output current increases.

In addition, in the discontinuous conduction mode (DCM), the flyback power conversion system 100 can also adjust the output current based on information associated with the waveform of the voltage of the auxiliary winding 114 as shown in FIG. 2, regardless of the output voltage. how is it.

For example, the output current is equal to the average of the secondary current 198 flowing through the secondary winding 112 during a switching time period, the switching time period including the demagnetization period corresponding to the demagnetization process.

Wherein I _out represents the output current, I _{sec_pk} represents the magnitude of the secondary current 198 when the power switch 120 is turned off, T _dem represents the duration of the demagnetization period, and T _s represents the duration of the switching time period.

As an example, according to Equation 5, the output current can be determined as follows: Where N represents the turns ratio between the primary winding 110 and the secondary winding 112, R _s represents the resistance of the current sensing resistor 130, T represents the integration period, and V _cs represents the flow through the primary during each switching cycle The primary current 196 associated with the primary current 196 of the winding 110 is a peak current sense signal.

According to Equation 6, if V _cs and T _dem /T _s do not change much, the output current can be adjusted regardless of the input voltage, the output voltage, or the inductance of the transformer including the primary winding 110 and the secondary winding 112, and therefore, the power conversion System 100 operates, for example, in a constant current mode.

However, when the power conversion system 100 is operating in the constant current mode, the power conversion system 100 needs to be protected. Therefore, it is very important to improve the technology for system protection.

The present invention relates to an integrated circuit. More specifically, the present invention provides systems and methods for protecting a power conversion system based on at least a feedback signal. Merely by way of example, the invention has been applied to a flyback power conversion system. However, it will be appreciated that the invention has a broader range of applications.

According to one embodiment, a system controller for protecting a power conversion system includes a protection element and a drive element. The protection element is configured to receive a demagnetization signal generated based on at least information associated with the feedback signal of the power conversion system, the processing being related to the demagnetization signal and the detected voltage generated based at least on information associated with the feedback signal Linked information, and generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal. The drive element is configured to receive the protection signal and output a drive signal to the switch, the switch configured to affect a primary current flowing through a primary winding of the power conversion system. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. The protection element and the drive element are further configured to: if the detected voltage and the demagnetization signal satisfy one or more conditions, output the drive signal to cause the switch to open and remain open thereby Protecting the power conversion system.

In accordance with another embodiment, a system controller for protecting a power conversion system includes a protection element and a drive element. The protection component is configured to receive a current sensing signal associated with a primary current flowing through a primary winding of the power conversion system based on a demagnetization signal generated based on information associated with a feedback signal of the power conversion system, processing Information associated with the demagnetization signal, the current sense signal, and the detected voltage generated based on at least information associated with the feedback signal, and based at least on the detected voltage, the demagnetization signal, and The information associated with the current sense signal generates a protection signal. Drive component is configured to receive The protection signal and a drive signal is output to the switch, the switch being configured to affect a primary current flowing through the primary winding. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. The protection element and the drive element are further configured to output the drive signal to cause the switch if the detected voltage, the demagnetization signal, and the current sense signal satisfy one or more conditions Disconnect and remain disconnected to protect the power conversion system.

In one embodiment, a method for protecting a power conversion system includes receiving a demagnetization signal generated based at least on information associated with a feedback signal of the power conversion system; processing and demagnetizing the signal and at least based on Information relating to the detected voltage generated by the information associated with the feedback signal; and generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal. The method also includes receiving the protection signal; generating a drive signal based on at least information associated with the protection signal; and outputting the switch to a primary current configured to affect a primary current flowing through a primary winding of the power conversion system Drive signal. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. Processing for outputting a drive signal to a switch configured to affect a primary current flowing through a primary winding of the power conversion system includes: if the detected voltage and the demagnetization signal satisfy one or more conditions, the output The drive signal is used to disconnect the switch and remain open to protect the power conversion system.

In another embodiment, a method for protecting a power conversion system includes receiving a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system; receiving and flowing through a primary of the power conversion system a current sense signal associated with the primary current of the winding; and processing information associated with the demagnetization signal, the current sense signal, and the detected voltage generated based at least on information associated with the feedback signal. The method also includes generating a protection signal based on at least information associated with the detected voltage, the demagnetization signal, and the current sense signal; receiving the protection signal; based at least on information associated with the protection signal Generating a drive signal; and outputting the drive signal to a switch configured to affect a primary current flowing through the primary winding. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. a processing packet for outputting the drive signal to a switch configured to affect a primary current flowing through the primary winding Comprising: if the detected voltage, the demagnetization signal, and the current sense signal satisfy one or more conditions, outputting the drive signal to cause the switch to open and remain open to protect the power conversion system.

One or more benefits may be obtained depending on the embodiment. These and other additional objects, features and advantages of the present invention will be fully understood from the description and appended claims.

100,300,900,1500,1600‧‧‧Power Conversion System

110,310,910,1610‧‧‧Primary winding

112,312,912,1612‧‧‧second winding

114,314,914,1514,1614‧‧‧Auxiliary winding

120,320,920,1620‧‧‧Power switch

130,330,930,1630‧‧‧ Current sensing resistor

140,340,940,1640‧‧‧ equivalent resistor

150,152,350,352,384,388,950,952,984,988,1112,1412,1550,1552,1650,1652,1684,1688‧‧‧Resistors

160,360,960,1660‧‧‧Rected diode

1593‧‧‧II

196,396,397,996,1696‧‧‧Primary current

198‧‧‧Secondary current

302,902,1109,1409,1602‧‧‧Sampling components

304,904,1604‧‧‧Demagnetization Detector

306,414,906,1106,1124,1406,1424,1428,1595,1606‧‧‧ capacitor

307,408,416,907,1103,1403,1607‧‧" switch

308, 412, 504, 908, 1128, 1608‧‧‧ reference signal generator

316,916,1616‧‧‧Oscillator

318,514,918,1618‧‧‧ and gate

322,922,1622‧‧‧ drive components

324,924,1624‧‧‧ or gate

332,614,932,1632‧‧‧ threshold voltage

326,328,410,502,926,928,1126,1426,1626,1628‧‧ ‧ comparator

336,506,510,936,1636‧‧‧ Trigger components

334,338,366,518,966,934,938,1142,1442,1634,1638,1666‧‧‧Comparative signals

342,942,1642‧‧‧ Current sensing signal

346,420,520,522,525,903,905,946,1008,1010,1088,1132,1136,1188,1310,1312,1432,1436,1488,1603,1605,1646‧‧ signals

348,948,1648‧‧‧ drive signals

354,954,1554,1654‧‧‧feedback voltage

356,956,1656‧‧‧ modulated signal

358,958,1658‧‧‧Detection signal

362,962,1662‧‧‧Sampling and holding voltage

364,422,516,964,1140,1664‧‧‧ reference signals

368,968,1668‧‧‧clock signal

370,970,1670‧‧ ‧ controller

372,374,376,378,380,972,974,976,978,980,1504,1506,1672,1674,1676,1678,1680‧‧‧ Terminal

386,986,1686‧‧‧Leading edge blanking (LEB) components

390,990,1690‧‧‧Error amplifier

392,992,1692‧‧‧Modulation components

393,993,1693‧‧‧output voltage

394,994,1694‧‧‧ constant current components

395‧‧‧Voltage

404,406‧‧‧current source

402, 508, 512, 1110, 1410‧‧ ‧ reverse gate

418,424,1134,1138,1434,1438‧‧‧ Current

516‧‧‧View signal

602, 604, 606, 608, 610, 612, 702, 704, 1202, 1204, 1702, 1704 ‧ ‧ waveform

706,708,709,710,1206,1208,1706,1708‧‧‧dotted lines

901,1601‧‧‧protective components

1002, 1102, 1302, 1402‧‧‧ Output voltage detector

1004,1304‧‧‧Voltage-controlled timer components

1006, 1306‧‧‧Timer comparator

1104, 1404‧‧‧Timer and comparator components

1108, 1408‧‧ amp amplifier

1114, 1116, 1118, 1120, 1122, 1414, 1416, 1418, 1420, 1422‧‧‧

1130, 1430‧‧ ‧ cycle counterattack components

1308, 1498‧‧‧ Peak current detector

1502‧‧‧Parasitic capacitor

Figure 1 is a simplified diagram showing a conventional flyback power conversion system with primary side sensing and adjustment.

Fig. 2 is a simplified diagram showing a conventional operation mechanism of the flyback power conversion system as shown in Fig. 1.

Figure 3 is a simplified diagram showing a power conversion system with primary side sensing and adjustment.

Figure 4 is a simplified diagram showing at least some of the elements of the constant current element as part of the power conversion system as shown in Figure 3.

Figure 5 is a simplified diagram showing at least some of the elements of the demagnetization detector as part of the power conversion system shown in Figure 3.

Fig. 6 is a simplified timing chart of the power conversion system as shown in Fig. 3.

(a) in Fig. 7 is a simplified diagram showing the relationship between the operating frequency and the output voltage of the power conversion system as shown in Fig. 3 in the constant current mode in the normal operation.

(b) in Fig. 7 is a simplified diagram showing the relationship between the demagnetization period duration and the output voltage of the power conversion system as shown in Fig. 3 in the constant current mode in the normal operation.

Figure 8 is a simplified diagram showing a power conversion system with primary side sensing and adjustment in accordance with an embodiment of the present invention.

Figure 9 is a simplified diagram showing certain elements of a protection element as part of a power conversion system as shown in Figure 8 in accordance with an embodiment of the present invention.

Figure 10 is a diagram showing the operation under normal operation and in accordance with an embodiment of the present invention. A simplified schema of the relationship between the demagnetization period duration of the power conversion system and the signal, as shown in Figure 8, under certain abnormal operations encountered by the source conversion system.

Figure 11 is a simplified diagram showing certain elements of a protection element as part of a power conversion system as shown in Figure 8 in accordance with another embodiment of the present invention.

Figure 12 is a simplified diagram showing a power conversion system with primary side sensing and adjustment in accordance with another embodiment of the present invention.

Figure 13 is a simplified diagram showing certain elements of a protection element as part of a power conversion system as shown in Figure 12, in accordance with an embodiment of the present invention.

Figure 14 is a diagram showing the demagnetization period duration and signal of the power conversion system as shown in Fig. 12 under normal operation and under certain abnormal operations to be protected from the power conversion system according to an embodiment of the present invention. A simplified schema of the relationship between.

Figure 15 is a simplified diagram showing certain elements of a protection element as part of a power conversion system as shown in Figure 12, in accordance with another embodiment of the present invention.

Figure 16 is a simplified diagram showing certain protection processes implemented by a power conversion system as shown in Figure 8 and/or a power conversion system as shown in Figure 12, in accordance with some embodiments of the present invention.

The present invention relates to an integrated circuit. More specifically, the present invention provides systems and methods for protecting a power conversion system based on at least a feedback signal. Merely by way of example, the invention has been applied to a flyback power conversion system. However, it will be appreciated that the invention has a broader range of applications.

Figure 3 is a simplified diagram showing a power conversion system with primary side sensing and adjustment. The power conversion system 300 includes a primary winding 310, a secondary winding 312, an auxiliary winding 314, a power switch 320, a current sensing resistor 330, an equivalent resistor 340 of an output cable, resistors 350 and 352, and a rectifying diode 360. And controller 370. The controller 370 includes a sampling component 302, a demagnetization detector 304, a capacitor 306, a switch 307, a reference signal generator 308, an oscillator 316, and a gate 318, a drive component 322, or a gate 324, comparators 326 and 328, and a flip-flop component. 336, leading edge blanking (LEB) component 386, resistors 384 and 388, error amplifier 390, modulation component 392, and constant current (CC) component 394. For example, the power switch 320 is a bipolar type of crystal body. In another example, power switch 320 is a MOS transistor. In yet another example, controller 370 includes terminals 372, 374, 376, 378, and 380.

For example, auxiliary winding 314 is magnetically coupled to secondary winding 312, which together with one or more other components generates an output voltage 393. In another example, the information related to the output voltage is processed by a voltage divider of resistors 350 and 352 and used to generate a feedback voltage 354 that is received by terminal 372 (e.g., terminal FB) of controller 370 . In yet another example, sampling element 302 samples feedback voltage 354 and the sampled signal is held at capacitor 306. As an example, error amplifier 390 compares sampled and held voltage 362 with reference signal 364 generated by reference signal generator 308 and outputs an error associated with referenced and held voltage 362 relative to reference signal 364. The signal 366 is compared. As another example, comparison signal 366 is received by modulation element 392, which receives clock signal 368 from oscillator 316 and outputs modulation signal 356 (eg, CV_ctrl). For example, the comparison signal 366 is used to control the pulse width of Pulse Width Modulation (PWM) and/or the switching frequency of Pulse Frequency Modulation (PFM) to adjust the output voltage in the constant voltage mode. In another example, the demagnetization detector 304 determines the duration of the demagnetization period based on the feedback voltage 354 and outputs a detection signal 358 to the constant current element 394, which generates a signal 346 (eg, CC_ctrl). In yet another example, both modulated signal 356 and signal 346 are received by AND gate 318 to affect flip-flop element 336 and in turn affect drive element 322. In yet another example, drive element 322 outputs drive signal 348 through terminal 376 to affect the state of power switch 320. In yet another example, primary current 396 flowing through primary winding 310 is sensed with current sense resistor 330 and current sense signal 342 is generated by LEB element 386 and received by comparators 326 and 328. In yet another example, comparator 326 and comparator 328 output comparison signals 334 and 338 to OR gate 324, respectively, to affect flip-flop element 336.

As an example, when the magnitude of the sampled and held voltage 362 is less than the reference signal 364, the error amplifier 390 outputs a comparison signal 366 of a logic high level. In some embodiments, power conversion system 300 operates in a constant current mode.

FIG. 4 is a simplified diagram showing at least some of the elements of constant current element 394 that are part of power conversion system 300. Constant current element 394 includes a reverse gate 402, a current source 404, and 406, switch 408, capacitor 414, comparator 410, and reference signal generator 412.

For example, when sense signal 358 is at a logic low level, switch 408 is open (eg, turned off) and switch 416 is closed (eg, turned "on"). In another example, current source 404 provides current 418 (eg, I ₀ ) to charge capacitor 414 and, in response, the magnitude of signal 420 increases. As an example, when detection signal 358 is at a logic high level, switch 416 is open (eg, turned off) and switch 408 is closed (eg, turned "on"). As another example, capacitor 414 is discharged by current source 406, current source 406 provides current 424 (eg, I ₁ ), and the magnitude of signal 420 decreases. For example, comparator 410 receives signal 420 and reference signal 422 generated by reference signal generator 412 and outputs signal 346.

FIG. 5 is a simplified diagram showing at least some of the components of the demagnetization detector 304 as part of the power conversion system 300. The demagnetization detector 304 includes a comparator 502, a reference signal generator 504, flip-flop elements 506 and 510, reverse gates 508 and 512, and a gate 514. For example, comparator 502 compares feedback signal 354 to view signal 516 (eg, 0.1 V) generated by reference signal generator 504 and outputs a comparison signal 518 that is received by flip-flop elements 506 and 510. In another example, the reverse gate 508 receives the modulated signal 356 and outputs a signal 520 to the flip-flop elements 506 and 510. In yet another example, AND gate 514 receives signal 522 from flip-flop element 506 and signal 525 from reverse gate 512 and outputs a detection signal 358.

FIG. 6 is a simplified timing diagram of power conversion system 300. Waveform 602 represents feedback voltage 354 as a function of time, waveform 604 represents detection signal 358 as a function of time, and waveform 606 represents signal 420 as a function of time. Waveform 608 represents signal 346 as a function of time, waveform 610 represents drive signal 348 as a function of time, and waveform 612 represents current sense signal 342 as a function of time.

Figure 6 shows four time periods. A switching time period includes an on period T _on and an off period T _off , and corresponds to a modulation frequency. The off period T _off includes a demagnetization period T _demag . The on-period begins at time t ₀ and ends at time t ₁ , the demagnetization period begins at time t ₁ and ends at time t ₂ , and the off period begins at time t ₁ and ends at time t ₃ . For example, t ₀ t ₁ t ₂ t ₃ .

For example, at the beginning of the conduction period T _on (e.g., at t _0), the drive signal 348 from a logic low level to a logic high level (e.g., as shown in waveform 610), and in response, the power switch 320 is closed (eg, turned on). In another example, a transformer including primary winding 310 and secondary winding 312 stores energy and the magnitude of primary current 396 is increased (eg, linearly). In yet another example, the magnitude of current sense signal 342 is increased (eg, as shown by waveform 612). As an example, when current sense signal 342 reaches threshold voltage 332 (eg, V _thocp ), comparator 326 changes comparison signal 334 to turn off power switch 320. As another example, during the on-time period, the detection signal 358 (eg, Demag) remains at a logic low level (eg, as shown by waveform 604). As yet another example, switch 408 is open (eg, turned off) and switch 416 is closed (eg, turned "on"). As yet another example, capacitor 414 is charged (eg, at I ₀ ), and signal 420 is increased in size (eg, linearly) as shown by waveform 606.

In an example, at the beginning of the demagnetization period T _demag (eg, at t ₁ ), the drive signal 348 changes from a logic high level to a logic low level (eg, as shown by waveform 610), and in response, the switch 320 is disconnected (eg, turned off). In another example, the energy stored in the transformer is released to the output terminal and the demagnetization process begins. In yet another example, the magnitude of the primary current 397 flowing through the secondary winding 312 is reduced (eg, linearly). In yet another example, voltage 395 at auxiliary winding 314 maps output voltage 393 and generates a feedback voltage 354 through a voltage divider that includes resistors 350 and 352. As an example, when the secondary current drops to a low magnitude (eg, 0), the demagnetization process ends. As another example, a transformer including primary winding 310 and secondary winding 312 enters a resonant state. As another example, voltage 395 at auxiliary winding 314 has an approximately sinusoidal waveform. In an example, during the demagnetization period, the detection signal 358 (eg, Demag) remains at a logic high level (eg, as shown by waveform 604). In yet another example, switch 416 is open (eg, turned off) and switch 408 is closed (eg, turned "on"). In yet another example, capacitor 414 is discharged (eg, at I ₁ ), and signal 420 is reduced in size (eg, linearly), as shown by waveform 606. In yet another example, if the magnitude of the feedback voltage 354 becomes greater than the reference signal 516 (eg, 0.1 V), it is determined that the demagnetization process has begun. In yet another example, if the magnitude of the feedback voltage 354 becomes less than the reference signal 516 (eg, 0.1 V), it is determined that the demagnetization process has ended.

As an example, in the demagnetization process ends (e.g., at t _2), the detection signal 358 from a logic high level to a logic low level (e.g., as shown in the waveform 604). As another example, switch 408 is open (eg, turned off) and switch 416 is closed (eg, turned "on"). As yet another example, capacitor 414 is again charged and the magnitude of signal 420 is again increased (eg, linearly) as shown by waveform 606. As yet another example, when the size of the signal 420 becomes greater than the threshold voltage 614 (e.g., reference signal 422) (e.g., at t _3), the comparator 410 a signal 346 (e.g., CC_ctrl) changes from a logic low It is a logic high (eg, as shown by waveform 608). As yet another example, in response to a logic high signal 346, the drive member 322 from the drive signal 348 logic low level to a logic high level (e.g., at t _3, as shown in the waveform 610).

For example, the switching time period is determined as follows: Where I ₀ represents current 418 and I ₁ represents current 424.

The peak value of the primary current 396 is determined as follows: Where V _thocp represents the threshold voltage 332 and R _s represents the resistance of the current sensing resistor 330.

Assuming that the transmission efficiency of the transformer is 100%, the output current is determined as follows: Where N represents the turns ratio between the primary winding 310 and the secondary winding 312.

According to Equation 7-9, the output current is determined as follows: Where K is greater than 1. According to Equation 10, in some embodiments, the output current can be adjusted to be nearly constant.

The operating frequency in constant current mode can be determined as follows: Where F _cc represents the operating frequency in the constant current mode.

The duration of the demagnetization period can be determined as follows: Where L _m represents the inductance of the primary winding 310 and V _d represents the forward voltage drop of the rectifier diode 360.

According to Equation 11-12, the operating frequency in the constant current mode can be determined as follows:

Fig. 7(a) is a simplified diagram showing the relationship between the operating frequency of the power conversion system 300 and the output voltage 393 in the constant current mode under normal operation, and Fig. 7(b) is shown under normal operation. A simplified diagram of the relationship between the demagnetization period duration of the power conversion system 300 and the output voltage 393 in the constant current mode.

For example, if the threshold voltage 332 is nearly constant, the operating frequency (eg, F _cc ) in the constant current mode is proportional to the output voltage 393 (eg, as shown by waveform 702 in FIG. 7(a)), and the constant current mode The demagnetization period duration in is inversely proportional to the output voltage 393 (eg, as shown by waveform 704 in Figure 7(b)). In another example, the shaded area A between dashed lines 706 and 708 in FIG. 7(a) indicates a change in operating frequency in normal operation in consideration of a change in inductance of a transformer including the primary winding 310. In yet another example, the shaded area B between the dashed lines 709 and 710 in FIG. 7(b) indicates a change in the duration of the demagnetization period in normal operation in consideration of the change in inductance of the transformer including the primary winding 310.

As shown in FIG. 7(b), in some embodiments, the demagnetization period duration is changed in a small area (eg, shaded area B) relative to the output voltage 393 under normal operation. For example, when the demagnetization period duration exceeds the shaded area B, the power conversion system 300 can be considered not under normal operation. Thus, in another example, power conversion system 300 needs to be protected for certain abnormal operations.

Figure 8 is a simplified diagram showing a power conversion system with primary side sensing and adjustment in accordance with an embodiment of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. The power conversion system 900 includes a primary winding 910, a secondary winding 912, an auxiliary winding 914, a power switch 920, a current sensing resistor 930, an equivalent resistor 940 of the output cable, resistors 950 and 952, and a rectifying diode 960. And controller 970. Controller 970 includes protection element 901, sampling element 902, demagnetization detector 904, capacitor 906, switch 907, reference signal generator 908, oscillator 916, and gate 918, drive element 922, or gate 924, comparators 926 and 928. Flip-flop element 936, leading edge blanking (LEB) element 986, resistors 984 and 988, error amplifier 990, modulation element 992, and constant current (CC) element 994. For example, the power switch 920 is a bipolar transistor. In another example, power switch 920 is a MOS transistor. In yet another example, the control The controller 970 includes terminals 972, 974, 976, 978, and 980.

According to an embodiment, the auxiliary winding 914 is magnetically coupled to the secondary winding 912, which together with one or more other components generates an output voltage 993. For example, information related to the output voltage is processed by a voltage divider of resistors 950 and 952 and used to generate a feedback voltage 954 that is received by terminal 972 (e.g., terminal FB) of controller 970. In another example, sampling element 902 samples feedback voltage 954 and the sampled signal is held at capacitor 906. In yet another example, sampling element 902 samples feedback voltage 954 at a midpoint of the demagnetization process.

According to another embodiment, the error amplifier 990 compares the sampled and held voltage 962 with the reference signal 964 generated by the reference signal generator 908, and the output correlates with the error of the sampled and held voltage 962 relative to the reference signal 964. The comparison signal 966. For example, comparison signal 966 is received by modulation element 992, which receives clock signal 968 from oscillator 916 and outputs modulation signal 956 (eg, CV_ctrl). In another example, the comparison signal 966 is used to control the pulse width of the pulse width modulation (PWM) and/or the switching frequency of the pulse-frequency modulation (PFM) to adjust the output voltage in the constant voltage mode. In another example, when the magnitude of the sampled and held voltage 962 is less than the reference signal 964, the error amplifier 990 outputs a comparison signal 966 of a logic high level to operate the power conversion system 900 to operate in a constant current mode. In yet another example, the demagnetization detector 904 determines the duration of the demagnetization period based on the feedback voltage 954 and outputs a detection signal 958 to the constant current element 994, which generates a signal 946 (eg, CC_ctrl). In yet another example, both modulated signal 956 and signal 946 are received by AND gate 918 to affect flip-flop element 936.

According to yet another embodiment, the drive element 922 outputs a drive signal 948 through the terminal 976 to affect the state of the power switch 920. For example, primary current 996 flowing through primary winding 910 is sensed with current sense resistor 930, and current sense signal 942 is generated by LEB element 986 and received by comparators 926 and 928. In another example, comparator 926 and comparator 928 output comparison signals 934 and 938 to OR gate 924, respectively, to affect flip-flop element 936. In yet another example, the protection element 901 receives the feedback voltage 954 and outputs a signal 903 (eg, Fault) to the trigger element 936. In yet another example, the drive element 922 receives the signal 903 and the signal 905 from the trigger element and outputs a drive signal 948 to affect the power switch 920.

FIG. 9 is a simplified diagram showing certain elements of a protection element 901 as part of a power conversion system 900 in accordance with an embodiment of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. Protection element 901 includes an output voltage detector 1002, a voltage controlled timer element 1004, and a timer comparator 1006.

According to an embodiment, output voltage detector 1002 receives feedback voltage 954 and outputs a signal 1008 (eg, V _sap ). For example, signal 1008 (eg, V _sap ) is associated with (eg, approximately proportional to) output voltage 993. In another example, the voltage controlled timer component 1004 receives the signal 1008 and outputs a signal 1010. In another example, signal 1010 corresponds to a reference duration (eg, T _ref ) having a waveform relative to output voltage 993. In yet another example, the timer comparator 1006 compares the detection signal 958 indicative of the duration of the demagnetization period of the power conversion system 900 with the signal 1010 and outputs a signal 903 (eg, Fault). In yet another example, if the reference duration (eg, T _ref ) is less than the duration of the demagnetization period of the power conversion system 900, the timer comparator 1006 outputs a logic low level indicating that the power conversion system 900 is in normal operation. Signal 903 (eg, Fault). In yet another example, if the reference duration (eg, T _ref ) is greater than the duration of the demagnetization period of the power conversion system 900, the timer comparator 1006 outputs a logic high level indicating that the power conversion system is not in normal operation. Signal 903 (eg, Fault).

Where V _sap represents the signal 1088, V _d represents the forward voltage drop of the rectifier diode 960, R ₁ represents the resistance of the resistor 950, and R ₂ represents the resistance of the resistor 952. In yet another example, signal 1088 represents output voltage 993 under normal operation.

According to another embodiment, the reference duration (eg, T _ref ) is determined as follows: Where N represents the turns ratio between the primary winding 910 and the secondary winding 912, V _thocp represents the threshold voltage 932, and R _s represents the resistance of the current sensing resistor 930. In addition, L _m represents the inductance of the primary winding 910, V _out represents the output voltage 993, V _d represents the forward voltage drop of the rectifier diode 960, and M is a constant (eg, greater than 1). For example, M is in the range of 1.4 to 2. In another example, V _thocp has a fixed size.

Figure 10 is a diagram showing the relationship between the demagnetization period duration of the power conversion system 900 and the signal 1008 under normal operation and under certain abnormal operations to be protected from the power conversion system 900, in accordance with an embodiment of the present invention. Simplify the schema. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. Waveform 1202 represents the relationship between the demagnetization period duration and signal 1008 (eg, V _sap ), and waveform 1204 represents the relationship between reference duration T _{ref of} power conversion system 900 and signal 1008 (eg, V _sap ). For example, under normal operation, signal 1008 (eg, V _sap ) represents the output voltage 993 of power conversion system 900.

As shown in FIG. 10, in some embodiments, under normal operation, the demagnetization period duration is varied relative to signal 1008 in a small region (eg, shaded region E between dashed lines 1206 and 1208). For example, when the demagnetization period duration changes in the shaded area E, the drive signal 948 is output as a modulation signal to turn the power switch 920 on and off in one switching cycle. In another example, when the demagnetization period duration enters another shaded area F below the waveform 1204 relative to the signal 1008, the signal 1008 does not represent the output voltage 993, and the power conversion system 900 is in a condition that the power conversion system 900 should be protected from encounters Some unusual operations. In another example, power switch 920 is turned off (eg, turned off) to protect power conversion system 900. In yet another example, waveform 1204 is parallel to waveform 1202.

Figure 11 is a simplified diagram showing certain elements of a protection element 901 as part of a power conversion system 900 in accordance with another embodiment of the present invention. This illustration is only an example, and should not unduly limit the scope of the patent application. Those skilled in the art will recognize many variations, substitutions and modifications. Protection element 901 includes an output voltage detector 1102 and a timer and comparator element 1104. The output voltage detector 1102 includes a switch 1103, a sampling element 1109, and a capacitor 1106. The timer and comparator component 1104 includes an amplifier 1108, a reverse gate 1110, a transistor 1114, 1116, 1118, 1120, 1122, a resistor 1112, a capacitor 1124, a reference signal generator 1128, a comparator 1126, and a periodic counter-attack (cycle- Debounce) element 1130. For example, output voltage detector 1102 is an output voltage detector 1002, timer and comparator element 1104 is a combination of voltage controlled timer element 1004 and timer comparator 1006, and signal 1188 is a signal 1008.

According to an embodiment, the sampling element 1109 samples the feedback voltage 954 and the sampled signal is held at the capacitor 1106. For example, output voltage detector 1102 outputs a sampled and held signal 1188 (eg, V _sap ) to timer and comparator element 1104. In another example, the sampled and held signal 1188 is determined as follows: Where V _sap represents the signal 1188, V _d represents the forward voltage drop of the rectifier diode 960, R ₁ represents the resistance of the resistor 950, and R ₂ represents the resistance of the resistor 952. In yet another example, the sampling element 1109 samples the feedback voltage 954 at a time that is not earlier than the midpoint of the demagnetization period but no later than 5/6 of the demagnetization period from the beginning of the demagnetization period.

According to another embodiment, amplifier 1108 receives signal 1188 and outputs signal 1132 to transistor 1118 such that current 1134 flows through transistor 1114, transistor 1118, and resistor 1112. For example, during the demagnetization process, the reverse gate 1110 receives a detection signal 958 of a logic high level. In another example, transistor 1120 is turned "on" and transistor 1122 is turned "off". In yet another example, current 1138 flows through transistors 1116 and 1120 to charge capacitor 1124, and the magnitude of signal 1136 increases. In yet another example, comparator 1126 compares signal 1136 with reference signal 1140 from reference signal generator 1128 and outputs comparison signal 1142. In some embodiments, if power conversion system 900 is operating under normal operation, signal 1136 is larger than reference signal 1140, and comparator 1126 outputs a comparison signal 1142 of a logic low level. For example, signal 903 is a logic low level. In some embodiments, if power conversion system 900 is not operating under normal operation, signal 1136 is smaller than reference signal 1140, and comparator 1126 outputs a comparison signal 1142 of a logic high level. For example, signal 903 is at a logic high level. In another example, in response to the logic high level signal 903, the power switch 920 is turned off (eg, turned off) for a period of time that is at least longer than a switching time period (eg, without any modulation) to protect the power conversion system 900. In yet another example, in response to signal 903 of a logic high level, power conversion system 900 is turned off and power switch 920 remains off. In yet another example, after being turned off, power conversion system 900 is turned back on (eg, automatically or manually) and modulation begins again. In yet another example, the power switch 920 is again closed (eg, turned on) and turned off (eg, turned off) at a modulation frequency. In some embodiments, the periodic anti-attack element 1130 is omitted and the letter The number 903 is the same as the comparison signal 1142.

According to a further embodiment, the reference duration T _ref1 corresponding to the reference signal 1140 is determined as follows: Wherein R ₀ represents the resistance of the resistor 1112, C ₁ represents the capacitance of the capacitor 1124, and V _ref2 represents the reference signal 1140.

In yet another example, according to Equation 15, the reference duration T _ref1 is set equal to T _ref .

In some embodiments, according to Equations 17-18, the constant M is determined as follows:

For example, if N, L _m , V _thocp , V _ref2 , R _s , R ₁ , R ₂ , R ₀ and C _{1 are appropriately selected} , the constant M is greater than 1 such that the reference duration T _{ref1 has} with respect to the output voltage 993 A waveform similar to waveform 1204 as shown in FIG.

As discussed above and further emphasized herein, Figures 8, 9, and 11 are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. In an embodiment, the protection element 901 receives the sampled and held voltage 962 instead of the feedback voltage 954, and the protection element 901 does not include the output voltage detector 1002 or the output voltage detector 1102. For example, switch 1103 is switch 907, capacitor 1106 is capacitor 906, and sampling element 1109 is sampling element 902. In another example, sampling element 902 samples feedback voltage 954 at a midpoint of the demagnetization period. In another embodiment, the threshold voltage 932 does not have a fixed size, as shown in Figures 12 and 13.

As discussed above and further emphasized herein, FIG. 10 is merely an example and should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. For example, waveform 1202 and waveform 1204 are affected by current sense signal 996. Therefore, the protection element receives the current sensing signal as an input, as shown in FIG.

Figure 12 is a simplified diagram showing a power conversion system with primary side sensing and adjustment in accordance with another embodiment of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. The power conversion system 1600 includes a primary winding 1610, a secondary winding 1612, an auxiliary winding 1614, a power switch 1620, a current sensing resistor 1630, an equivalent resistor 1640 of the output cable, resistors 1650 and 1652, a rectifying diode 1660, and Controller 1670. Controller 1670 includes protection element 1601, sampling element 1602, demagnetization detector 1604, capacitor 1606, switch 1607, reference signal generator 1608, oscillator 1616, and gate 1618, drive element 1622, or gate 1624, comparators 1626 and 1628. Flip-flop component 1636, leading edge blanking (LEB) component 1686, resistors 1684 and 1688, error amplifier 1690, modulation component 1692, and constant current (CC) component 1694. For example, power switch 1620 is a bipolar transistor. In another example, power switch 1620 is a MOS transistor. In yet another example, controller 1670 includes terminals 1672, 1674, 1676, 1678, and 1680.

According to an embodiment, the auxiliary winding 1614 is magnetically coupled to the secondary winding 1612, which together with one or more other components generates an output voltage 1693. For example, information related to the output voltage is processed by a voltage divider of resistors 1650 and 1652 and used to generate a feedback voltage 1654 that is received by terminal 1672 (eg, terminal FB) of controller 1670. In another example, sampling component 1602 samples feedback voltage 1654 and the sampled signal is held at capacitor 1606. In yet another example, the sampling element 1602 samples the feedback voltage 1654 at the midpoint of the demagnetization process.

According to another embodiment, error amplifier 1690 compares sampled and held voltage 1662 with reference signal 1664 generated by reference signal generator 1608, and outputs an error correlation with referenced and held voltage 1662 relative to reference signal 1664. The comparison signal 1666. For example, comparison signal 1666 is received by modulation element 1692, which receives clock signal 1668 from oscillator 1616 and outputs modulation signal 1656 (eg, CV_ctrl). In another example, the comparison signal 1666 is used to control the pulse width of the pulse width modulation (PWM) and/or the switching frequency of the pulse-frequency modulation (PFM) to adjust the output voltage in the constant voltage mode. In yet another example, when the magnitude of the sampled and held voltage 1662 is less than the reference signal 1664, the error amplifier 1690 outputs a comparison signal 1666 of a logic high level to operate the power conversion system 1600 to operate in a constant current mode. In yet another example, the demagnetization detector 1604 determines the duration of the demagnetization period based on the feedback voltage 1654 and outputs a detection signal 1658 to the constant current element 1694, which generates a signal 1646 (eg, CC_ctrl). In yet another example, tune Both the signal 1656 and the signal 1646 are received by the AND gate 1618 to affect the flip-flop element 1636.

According to yet another embodiment, the drive element 1622 outputs a drive signal 1648 through the terminal 1676 to affect the state of the power switch 1620. For example, primary current 1696 flowing through primary winding 1610 is sensed with current sense resistor 1630, and current sense signal 1642 is generated by LEB element 1686 and received by comparators 1626 and 1628. In another example, comparator 1626 and comparator 1628 output comparison signals 1634 and 1638 to OR gate 1624, respectively, to affect flip-flop element 1636. In yet another example, protection element 1601 receives feedback voltage 1654 and current sense signal 1642 and outputs signal 1603 (eg, Fault) to flip-flop element 1636. In yet another example, the drive element 1622 receives the signal 1603 and the signal 1605 from the trigger element and outputs a drive signal 1648 to affect the power switch 1620.

Figure 13 is a simplified diagram showing certain elements of protection element 1601 as part of power conversion system 1600, in accordance with an embodiment of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. Protection element 1601 includes an output voltage detector 1302, a voltage controlled timer element 1304, a timer comparator 1306, and a peak current detector 1308.

According to an embodiment, output voltage detector 1302 receives feedback voltage 1654 and outputs signal 1310 (eg, V _sap ). For example, signal 1310 (eg, V _sap ) is associated with (eg, approximately proportional to) output voltage 1693. In another example, peak current detector 1308 receives current sense signal 1642 and outputs threshold voltage 1632. In yet another example, the voltage controlled timer element 1304 receives the signal 1310 and the threshold voltage 1632 and outputs a signal 1312. In yet another example, signal 1312 corresponds to a reference duration (eg, T _ref3 ). In yet another example, the timer comparator 1306 compares the detection signal 1658 indicative of the duration of the demagnetization period of the power conversion system 1600 with the signal 1312 and outputs a signal 1603 (eg, Fault). In yet another example, if the reference duration (eg, T _ref3 ) is less than the duration of the demagnetization period of the power conversion system 1600, the timer comparator 1306 outputs a logic low level indicating that the power conversion system 1600 is in normal operation. Signal 1603 (eg, Fault). In yet another example, if the reference duration (eg, T _ref3 ) is greater than the duration of the demagnetization period of the power conversion system 1600, the timer comparator 1306 outputs a logic high level indicating that the power conversion system 1600 is not in normal operation. Signal 1603 (for example, Fault).

According to another embodiment, the reference duration (eg, T _ref3 ) is determined as follows: Where N represents the turns ratio between the primary winding 1610 and the secondary winding 1612, V _thocp represents the threshold voltage 1632, and R _s represents the resistance of the current sensing resistor 1630. In addition, L _m represents the inductance of the primary winding 1610, V _out represents the output voltage 1693, V _d represents the forward voltage drop of the rectifier diode 1660, and M is a constant (eg, greater than 1). For example, M is in the range of 1.4 to 2. In another example, V _thocp has a variable size.

Figure 14 is a diagram showing the relationship between the demagnetization period duration of the power conversion system 1600 and the signal 1310 under normal operation and under certain abnormal operations to be protected from the power conversion system 1600, in accordance with an embodiment of the present invention. Simplify the schema. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. Waveform 1702 represents the relationship between the demagnetization period duration and signal 1310 (eg, V _sap ), and waveform 1704 represents the relationship between reference duration T _{ref3 of} power conversion system 1600 and signal 1310. For example, under normal operation, signal 1310 (eg, V _sap ) represents the output voltage 1693 of power conversion system 1600.

As shown in FIG. 14, in some embodiments, under normal operation, the demagnetization period duration is varied relative to signal 1310 in a small region (eg, shaded region G between dashed lines 1706 and 1708). For example, when the demagnetization period duration changes in the shaded area G, the drive signal 1648 is output as a modulation signal to turn the power switch 1620 on and off in one switching cycle. In another example, when the demagnetization period duration enters another shaded region H below the waveform 1704 relative to the signal 1310, the signal 1310 does not represent the output voltage 1693, and the power conversion system 1600 is in a condition that the power conversion system 1600 should be protected from encounters Some unusual operations. In another example, power switch 1620 is turned off (eg, turned off) to protect power conversion system 1600. In yet another example, waveform 1704 is parallel to waveform 1702. In yet another example, waveforms 1702 and 1704 both change with threshold voltage 1632.

Figure 15 is a simplified diagram showing certain elements of a protection element 1601 as part of a power conversion system 1600 in accordance with another embodiment of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many Variants, replacements, and modifications. Protection element 1601 includes an output voltage detector 1402, a timer and comparator element 1404, and a peak current detector 1498. Output voltage detector 1402 includes a switch 1403, a sampling element 1409, and a capacitor 1406. The timer and comparator element 1404 includes an amplifier 1408, a reverse gate 1410, a transistor 1414, 1416, 1418, 1420, 1422, a resistor 1412, a capacitor 1424, a comparator 1426, and a periodic de-attack element 1430. For example, output voltage detector 1402 is output voltage detector 1302, peak current detector 1498 is peak current detector 1308, and timer and comparator element 1404 is a combination of voltage controlled timer element 1304 and timer comparator 1306, and Signal 1488 is signal 1310. In another example, switch 1403, sampling element 1409, and capacitor 1406 are identical to switch 1607, sampling element 1602, and capacitor 1606, respectively. In yet another example, capacitor 1428 is included in peak current detector 1498. In yet another example, capacitor 1428 is included in timer and comparator element 1404.

According to an embodiment, sampling element 1409 samples feedback voltage 1654 and the sampled signal is held at capacitor 1406. For example, output voltage detector 1402 outputs a sampled and held signal 1488 (eg, V _sap ) to timer and comparator element 1404. In another example, the sampled and held signal 1488 is determined as follows: Where V _sap represents the signal 1488, V _d represents the forward voltage drop of the rectifier diode 1660, R ₁ represents the resistance of the resistor 1650, and R ₂ represents the resistance of the resistor 1652. In yet another example, the sampling element 1409 samples the feedback voltage 1654 at a time that is not earlier than the midpoint of the demagnetization period but no later than 5/6 of the demagnetization period from the beginning of the demagnetization period.

According to another embodiment, amplifier 1408 receives signal 1488 and outputs signal 1432 to transistor 1418 such that current 1434 flows through transistor 1414, transistor 1418, and resistor 1412. For example, during the demagnetization process, the reverse gate 1410 receives a detection signal 1658 of a logic high level. In another example, transistor 1420 is turned "on" and transistor 1422 is turned "off". In yet another example, current 1438 flows through transistors 1416 and 1420 to charge capacitor 1424, and the size of signal 1436 increases. In yet another example, peak current detector 1498 receives current sense signal 1642 and outputs threshold voltage 1632. In yet another example, comparator 1426 compares signal 1436 to threshold voltage 1632 and outputs comparison signal 1442. In some embodiments, if the power conversion system 1600 is operating under normal operation, the magnitude of the signal 1436 is greater than the threshold voltage. 1632, and comparator 1426 outputs a comparison signal 1442 of a logic low level. For example, signal 1603 is at a logic low level. In some embodiments, if power conversion system 1600 is not operating under normal operation, signal 1436 is less than threshold voltage 1632, and comparator 1426 outputs a comparison signal 1442 of a logic high level. For example, signal 1603 is at a logic high level. In another example, in response to the logic high level signal 1603, the power switch 1620 is turned off (eg, turned off) for a period of time that is at least longer than one switching time period (eg, without any modulation) to protect the power conversion system. 1600. In yet another example, in response to signal 1603 of a logic high level, power conversion system 1600 is turned off and power switch 1620 remains off. In yet another example, after being turned off, the power conversion system 1600 is turned back on (eg, automatically or manually) and modulation begins again. In yet another example, the power switch 1620 is again closed (eg, turned on) and off (eg, turned off) at a modulation frequency. In some embodiments, the periodic de-attack element 1430 is omitted and the signal 1603 is the same as the comparison signal 1442.

According to a further embodiment, the reference duration T _ref4 corresponding to the threshold voltage 1632 is determined as follows: Where R ₀ represents the resistance of the resistor 1412 and C ₁ represents the capacitance of the capacitor 1424.

In yet another example, according to Equation 20, the reference duration T _ref4 is set equal to T _ref3 .

In some embodiments, according to Equations 22-23, the constant M is determined as follows:

For example, if N, L _m , R _s , R ₁ , R ₂ , R ₀ and C ₁ are appropriately selected, the constant M is greater than 1 such that the reference duration T _ref4 has an image with respect to the output voltage 1693 as shown in FIG. Waveform 1704 is shown as a similar waveform.

Referring back to FIG. 8, in some embodiments, if resistor 950 is open or if resistor 952 is shorted, demagnetization detector 904 cannot detect the duration of the demagnetization period and feedback voltage 954 has a low magnitude (eg, 0). For example, as shown in FIG. 11, capacitor 1124 is not charged and comparator 1126 outputs a comparison signal 1142 of a logic high level. In another example, signal 903 is at a logic high level and power switch 920 is off (eg, turned off) To protect the power conversion system 900.

Referring back to FIG. 12, in some embodiments, if resistor 1650 is open or if resistor 1652 is shorted, demagnetization detector 1604 is unable to detect the duration of the demagnetization period and feedback voltage 1654 has a low magnitude (eg, 0). . For example, as shown in FIG. 15, capacitor 1424 is not charged and comparator 1426 outputs a comparison signal 1442 of a logic high level. In another example, signal 1603 is at a logic high level and power switch 1620 is turned off (eg, turned off) to protect power conversion system 1600.

As discussed above and further emphasized herein, Figures 12, 13 and 15 are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. For example, protection element 1601 receives sampled and held voltage 1662 instead of feedback voltage 1654, and protection element 1601 does not include output voltage detector 1302 or output voltage detector 1402. For example, switch 1403 is switch 1607, capacitor 1406 is capacitor 1606, and sampling element 1409 is sampling element 1602. In another example, sampling element 1602 samples feedback voltage 1654 at a midpoint of the demagnetization period.

Figure 16 is a simplified diagram showing certain protection processes implemented by power conversion system 900 and/or power conversion system 1600, in accordance with some embodiments of the present invention. The drawings are merely examples, which should not unduly limit the scope of the claimed scope. Those skilled in the art will recognize many variations, substitutions and modifications. As shown in FIG. 16, the power conversion system 1500 includes an auxiliary winding 1514, resistors 1550 and 1552, a capacitor 1595, and a diode 1593.

In an embodiment, power conversion system 1500 is the same as power conversion system 900. For example, the auxiliary winding 1514 is the same as the auxiliary winding 914, and the resistors 1550 and 1552 are the same as the resistors 950 and 952, respectively. In some embodiments, if the terminal 1504 (eg, T _aux ) of the auxiliary winding 1514 is open, the demagnetization detector cannot detect the duration of the demagnetization period and the feedback voltage 1554 (eg, the feedback voltage 954) has a low magnitude (eg, 0). For example, as shown in FIG. 11, capacitor 1124 is not charged and comparator 1126 outputs a comparison signal 1142 of a logic high level. In another example, signal 903 is at a logic high level and power switch 920 is turned off (eg, turned off) to protect power conversion system 900. In some embodiments, if terminal 1506 (eg, T _gnd ) of auxiliary winding 1514 is open, parasitic capacitor 1502 is present. For example, as shown in FIG. 8, the duration of the demagnetization period detected by the demagnetization detector 904 is close to the actual duration of the demagnetization period. In another example, as shown in FIG. 11, the sampled and held signal 1188 associated with the feedback voltage 954 has a magnitude that is less than the size under normal operation, the magnitude of the signal 1136 is less than the reference signal 1140, and the comparator 1126 A comparison signal 1142 of a logic high level is output. In yet another example, signal 903 is at a logic high level and power switch 920 is turned off (eg, turned off) to protect power conversion system 900.

In another embodiment, power conversion system 1500 is a power conversion system 1600. For example, the auxiliary winding 1514 is the same as the auxiliary winding 1614, and the resistors 1550 and 1552 are identical to the resistors 1650 and 1652, respectively. In some embodiments, if the terminal 1504 (eg, T _aux ) of the auxiliary winding 1514 is open, the demagnetization detector cannot detect the duration of the demagnetization period and the feedback voltage 1554 (eg, the feedback voltage 1654) has a low magnitude (eg, 0). For example, as shown in FIG. 15, capacitor 1424 is not charged and comparator 1426 outputs a comparison signal 1442 of a logic high level. In another example, signal 1603 is at a logic high level and power switch 1620 is turned off (eg, turned off) to protect power conversion system 1600. In some embodiments, if terminal 1506 (eg, T _gnd ) of auxiliary winding 1514 is open, parasitic capacitor 1502 is present. For example, as shown in Fig. 12, the duration of the demagnetization period detected by the demagnetization detector 1604 is close to the actual duration of the demagnetization period. In another example, as shown in FIG. 14, the sampled and held signal 1488 associated with the feedback voltage 1654 has a magnitude that is less than the size under normal operation, the magnitude of the signal 1436 is less than the threshold voltage 1632, and the comparator 1426 A comparison signal 1442 of a logic high level is output. In yet another example, signal 1603 is at a logic high level and power switch 1620 is turned off (eg, turned off) to protect power conversion system 1600.

In accordance with another embodiment, a system controller for protecting a power conversion system includes a protection element and a drive element. The protection element is configured to receive a demagnetization signal generated based on at least information associated with the feedback signal of the power conversion system, the processing being related to the demagnetization signal and the detected voltage generated based at least on information associated with the feedback signal Linked information, and generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal. The drive element is configured to receive the protection signal and output a drive signal to the switch, the switch configured to affect a primary current flowing through a primary winding of the power conversion system. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. The protection element and the drive element are also configured to: If the detected voltage and the demagnetization signal satisfy one or more conditions, the drive signal is output to cause the switch to open and remain open to protect the power conversion system. For example, the system controller is implemented at least according to FIG. 8, FIG. 9, FIG. 10, and/or FIG.

In accordance with another embodiment, a system controller for protecting a power conversion system includes a protection element and a drive element. The protection element is configured to receive a current sensing signal associated with a primary current flowing through a primary winding of the power conversion system based on a demagnetization signal generated based on information associated with a feedback signal of the power conversion system, processing Information associated with the demagnetization signal, the current sense signal, and the detected voltage generated based on at least information associated with the feedback signal, and based at least on the detected voltage, the demagnetization signal, and The information associated with the current sense signal generates a protection signal. The drive element is configured to receive the protection signal and output a drive signal to the switch, the switch configured to affect a primary current flowing through the primary winding. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. The protection element and the drive element are further configured to output the drive signal to cause the switch if the detected voltage, the demagnetization signal, and the current sense signal satisfy one or more conditions Disconnect and remain disconnected to protect the power conversion system. For example, the system controller is implemented at least in accordance with FIG. 12, FIG. 13, FIG. 14, and/or FIG.

In one embodiment, a method for protecting a power conversion system includes receiving a demagnetization signal generated based at least on information associated with a feedback signal of the power conversion system; processing and demagnetizing the signal and at least based on Information relating to the detected voltage generated by the information associated with the feedback signal; and generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal. The method also includes receiving the protection signal; generating a drive signal based on at least information associated with the protection signal; and outputting the switch to a primary current configured to affect a primary current flowing through a primary winding of the power conversion system Drive signal. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. Processing for outputting a drive signal to a switch configured to affect a primary current flowing through a primary winding of the power conversion system includes: if the detected voltage and the demagnetization signal satisfy one or more conditions, the output The drive signal is used to disconnect the switch and remain open to protect the power conversion system. For example, the method is at least This is achieved according to Fig. 8, Fig. 9, Fig. 10, and/or Fig. 11.

In another embodiment, a method for protecting a power conversion system includes receiving a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system; receiving and flowing through a primary of the power conversion system a current sense signal associated with the primary current of the winding; and processing information associated with the demagnetization signal, the current sense signal, and the detected voltage generated based at least on information associated with the feedback signal. The method also includes generating a protection signal based on at least information associated with the detected voltage, the demagnetization signal, and the current sense signal; receiving the protection signal; based at least on information associated with the protection signal Generating a drive signal; and outputting the drive signal to a switch configured to affect a primary current flowing through the primary winding. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system. The processing for outputting the drive signal to a switch configured to affect a primary current flowing through the primary winding includes if the detected voltage, the demagnetization signal, and the current sense signal satisfy one or more Conditionally, the drive signal is output to cause the switch to open and remain open to protect the power conversion system. For example, the method is implemented at least according to FIG. 12, FIG. 13, FIG. 14, and/or FIG.

For example, some or all of the elements of various embodiments of the invention, alone and/or in combination with at least one other element, utilize one or more of the software elements, one or more hardware elements, and/or software and hardware elements. One or more combinations are implemented. In another example, some or all of the elements of various embodiments of the invention are implemented in one or more circuits, alone and/or in combination with at least one other element, such as in one or more analog circuits and/or Implemented in one or more digital circuits. In yet another example, various embodiments and/or examples of the invention may be combined.

Although specific embodiments of the invention have been described, it will be apparent to those skilled in the art Therefore, it is to be understood that the invention is not limited by

300‧‧‧Power Conversion System

310‧‧‧Primary winding

312‧‧‧Secondary winding

314‧‧‧Auxiliary winding

320‧‧‧Power switch

330‧‧‧current sensing resistor

340‧‧‧ equivalent resistor

350,352,384,388‧‧‧Resistors

360‧‧‧Rected diode

396,397‧‧‧Primary current

302‧‧‧Sampling components

304‧‧‧Demagnetization Detector

306‧‧‧ capacitor

307‧‧‧ switch

308‧‧‧Reference Signal Generator

316‧‧‧Oscillator

318‧‧‧ and gate

322‧‧‧Drive components

324‧‧‧ or gate

332‧‧‧ threshold voltage

326,328‧‧‧ comparator

336‧‧‧Flip-flop components

334,338,366‧‧‧Comparative signals

342‧‧‧ Current sensing signal

346‧‧‧ signal

348‧‧‧Drive signal

354‧‧‧feedback voltage

356‧‧‧ modulated signal

358‧‧‧Detection signal

362‧‧‧Sampling and maintaining voltage

364‧‧‧ reference signal

368‧‧‧clock signal

370‧‧‧ Controller

372,374,376,378,380‧‧‧ terminals

386‧‧‧ Leading Edge Blanking (LEB) components

390‧‧‧Error amplifier

392‧‧‧Modulation components

393‧‧‧ Output voltage

394‧‧‧ constant current components

395‧‧‧Voltage

Claims (44)

A system controller for protecting a power conversion system, the system controller including: a protection component configured to receive a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system, processing and demagnetizing a signal and information associated with the detected voltage generated based at least on information associated with the feedback signal, and generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal; and a drive component Configuring to receive the protection signal and output a drive signal to a switch, the switch configured to affect a primary current flowing through a primary winding of the power conversion system; wherein: the detected voltage and an output of the power conversion system Voltage dependent; and the demagnetization signal is related to a demagnetization period of the power conversion system; wherein the protection element and the driving element are further configured to: if the detected voltage and the demagnetization signal satisfy one or more a condition that outputs the drive signal to cause the switch to open and remain open Protection of the power conversion system. The system controller of claim 1, wherein the protection element and the driving element are further configured to: if the detected voltage and the demagnetization signal satisfy the one or more conditions, Then the system controller is turned off. The system controller of claim 1, wherein the protection element and the driving element are further configured to: responsive to the detected voltage and the demagnetization signal not satisfying the one or more The condition is that the driving signal is output as a modulation signal to turn the switch on and off during a switching time period corresponding to the modulation frequency. The system controller of claim 3, wherein the protection element and the driving element are further configured to: if the detected voltage and the demagnetization signal satisfy the one or more conditions, The drive signal is then output to turn the switch off without any modulation. The system controller of claim 3, wherein the protection element and the driving element are further configured to: if the detected voltage and the demagnetization signal satisfy the one or more conditions, And then outputting the driving signal to turn off the switch for at least a period longer than the switching time period. The system controller of claim 1, wherein the protection element is further configured to receive the detected voltage generated based on at least information associated with the feedback signal. The system controller of claim 1, wherein the protection element is further configured to receive the feedback signal and generate the detected voltage based on at least information associated with the feedback signal. The system controller of claim 1, wherein the detected voltage and the demagnetization signal are if the demagnetization period is less than a threshold period corresponding to the detected voltage for a duration The one or more conditions are met. The system controller of claim 8, wherein the duration of the threshold period is inversely proportional to the detected voltage. The system controller of claim 1, wherein the protection element comprises a voltage detector configured to receive the feedback signal and generate at least based on information associated with the feedback signal The detected voltage. The system controller of claim 10, wherein the voltage detector is configured to receive the feedback signal from a voltage signal generator coupled to an auxiliary winding of the power conversion system. The system controller of claim 11, wherein the voltage signal generator is configured to generate the feedback signal based on at least information associated with the output voltage, the output voltage and the power source The secondary winding of the conversion system is related. The system controller of claim 12, wherein the secondary winding is configured to release energy during the demagnetization period. The system controller of claim 10, wherein the protection element further comprises: a timer element configured to receive the detected voltage and generate at least based on information associated with the detected voltage a reference signal, the reference signal being associated with the threshold time period; and a comparator element configured to receive the reference signal and the demagnetization signal and based at least on a correlation with the reference signal and the demagnetization signal Information generates the protection signal. The system controller of claim 10, wherein the protection element further comprises: a timer and a comparator element configured to receive the detected voltage and the demagnetization signal and based at least on The detected voltage and the information associated with the demagnetization signal generate the guarantee Protection signal. The system controller of claim 15, wherein the voltage detector comprises: a sampling element configured to sample the feedback signal and generate the sampled signal; and a capacitor configured to receive the The signal is sampled and the detected voltage is generated. The system controller of claim 16, wherein the sampling element comprises a switch. The system controller of claim 15, wherein the timer and comparator components comprise: an amplifier comprising a first input terminal, a second input terminal, and an output terminal; the first transistor, including the first a transistor terminal, a second transistor terminal, and a third transistor terminal; a second transistor including a fourth transistor terminal, a fifth transistor terminal, and a sixth transistor terminal; and a third transistor including the seventh transistor a terminal, an eighth transistor terminal and a ninth transistor terminal; a fourth transistor comprising a tenth transistor terminal, an eleventh transistor terminal and a twelfth transistor terminal; and a fifth transistor comprising the thirteenth transistor a crystal terminal, a fourteenth transistor terminal, and a fifteenth transistor terminal; and a resistor including a first resistor terminal and a second resistor terminal; wherein: the first input terminal is configured to receive the detected a voltage; the second input terminal is coupled to the sixth transistor terminal; the output terminal is coupled to the fourth transistor terminal and the first resistor terminal; the first transistor a terminal coupled to the seventh transistor terminal and the third transistor terminal; the third transistor terminal coupled to the fifth transistor terminal; the ninth transistor terminal coupled to the Eleventh transistor terminal; The tenth transistor terminal is coupled to the thirteenth transistor terminal and configured to receive a first signal associated with the demagnetization signal; the twelfth transistor terminal is coupled to the fourteenth The transistor terminal is also configured to output a second signal; and the fifteen transistor terminal is coupled to the second resistor terminal. The system controller of claim 18, wherein the timer and comparator component further comprises a comparator configured to receive the second signal and the reference signal and generate the protection Signal related comparison signal. The system controller of claim 19, wherein the timer and comparator elements further comprise a periodic anti-attack element configured to receive the comparison signal and output the protection signal . The system controller of claim 1, further comprising: a sample and hold component configured to receive the feedback signal and generate the sampled and held signal based on at least information associated with the feedback signal; An amplifier configured to receive the sampled and held signal and generate an amplified signal based at least on information associated with the sampled and held signal; and a modulating element configured to receive the amplified signal and based at least on The information associated with the amplified signal generates a modulated signal; wherein the drive element is further configured to receive a first signal associated with the modulated signal. A system controller for protecting a power conversion system, the system controller comprising: a protection component configured to receive a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system, receiving and flowing through A current sense signal associated with a primary current of a primary winding of the power conversion system, the process being associated with the demagnetization signal, the current sense signal, and the detected voltage generated based at least on information associated with the feedback signal And generating a protection signal based on at least information associated with the detected voltage, the demagnetization signal, and the current sense signal; and a drive component configured to receive the protection signal and output a drive signal to the switch The switch is configured to affect a primary current flowing through the primary winding; wherein: The detected voltage is related to an output voltage of the power conversion system; and the demagnetization signal is related to a demagnetization period of the power conversion system; wherein the protection element and the driving element are further configured to: if The detected voltage, the demagnetization signal, and the current sense signal satisfy one or more conditions, and the drive signal is output to cause the switch to open and remain open to protect the power conversion system. The system controller of claim 22, wherein the protection element and the driving element are further configured to: if the detected voltage, the demagnetization signal, and the current sensing signal satisfy one Or multiple conditions, then shut down the system controller. The system controller of claim 22, wherein the protection element and the driving element are further configured to: at least respond to the detected voltage, the demagnetization signal, and the current sensing signal The one or more conditions are not met, and the drive signal is output as a modulation signal to turn the switch on and off during a switching time period corresponding to the modulation frequency. The system controller of claim 24, wherein the protection element and the driving element are further configured to: if the detected voltage, the demagnetization signal, and the current sensing signal satisfy Said one or more conditions, the drive signal is output to open the switch without any modulation. The system controller of claim 24, wherein the protection element and the driving element are further configured to: if the detected voltage, the demagnetization signal, and the current sensing signal satisfy Said one or more conditions, said driving signal being output to open said switch for at least a longer period of time than said switching time period. The system controller of claim 22, wherein the protection element is further configured to receive the detected voltage generated based on at least information associated with the feedback signal. The system controller of claim 22, wherein the protection element is further configured to receive the feedback signal and generate the detected voltage based on at least information associated with the feedback signal. The system controller of claim 22, wherein if the demagnetization period is less than a threshold period corresponding to the detected voltage and the current sensing signal for a duration, the The detection voltage, the demagnetization signal, and the current sense signal satisfy the one or more conditions. The system controller of claim 29, wherein the duration of the threshold period is inversely proportional to the detected voltage. The system controller of claim 22, wherein the protection element comprises a voltage detector configured to receive the feedback signal and generate at least based on information associated with the feedback signal The detected voltage. The system controller of claim 31, wherein the voltage detector is configured to receive the feedback signal from a voltage signal generator coupled to an auxiliary winding of the power conversion system. The system controller of claim 32, wherein the voltage signal generator is configured to generate the return signal based on at least information associated with the output voltage, the output voltage and the The secondary winding of the power conversion system is related. The system controller of claim 33, wherein the secondary winding is configured to release energy during the demagnetization period. The system controller of claim 31, wherein the protection element further comprises: a peak detecting component configured to receive the current sensing signal and based at least on an associated with the current sensing signal Information generating a threshold signal; a timer component configured to receive the detected voltage and the threshold signal and generate a reference signal based on at least information associated with the detected voltage and the threshold signal, the reference signal and The threshold time period is associated; and a comparator element configured to receive the reference signal and the demagnetization signal and generate the protection signal based at least on information associated with the reference signal and the demagnetization signal. The system controller of claim 31, wherein the protection element further comprises: a peak detecting component configured to receive the current sensing signal and based at least on an associated with the current sensing signal Information generating a threshold signal; and a timer and comparator element configured to receive the detected voltage, the demagnetization signal, and the threshold signal, and based at least on the detected voltage, the demagnetization signal, and the The information associated with the threshold signal generates the protection signal. The system controller of claim 36, wherein the voltage detector package A sampling element configured to sample the feedback signal and generate the sampled signal; and a capacitor configured to receive the sampled signal and generate the detected voltage. The system controller of claim 37, wherein the sampling element comprises a switch. The system controller of claim 36, wherein the timer and comparator components comprise: an amplifier comprising a first input terminal, a second input terminal, and an output terminal; the first transistor, including the first a transistor terminal, a second transistor terminal, and a third transistor terminal; a second transistor including a fourth transistor terminal, a fifth transistor terminal, and a sixth transistor terminal; and a third transistor including the seventh transistor a terminal, an eighth transistor terminal and a ninth transistor terminal; a fourth transistor comprising a tenth transistor terminal, an eleventh transistor terminal and a twelfth transistor terminal; and a fifth transistor comprising the thirteenth transistor a crystal terminal, a fourteenth transistor terminal, and a fifteenth transistor terminal; and a resistor including a first resistor terminal and a second resistor terminal; wherein: the first input terminal is configured to receive the detected a voltage; the second input terminal is coupled to the sixth transistor terminal; the output terminal is coupled to the fourth transistor terminal and the first resistor terminal; the first transistor a terminal coupled to the seventh transistor terminal and the third transistor terminal; the third transistor terminal coupled to the fifth transistor terminal; the ninth transistor terminal coupled to the An eleventh transistor terminal; the tenth transistor terminal is coupled to the thirteenth transistor terminal and configured to receive a first signal related to the demagnetization signal; The twelfth transistor terminal is coupled to the fourteenth transistor terminal and configured to output a second signal; and the fifteen transistor terminal is coupled to the second resistor terminal. The system controller of claim 39, wherein the timer and comparator element further comprises a comparator configured to receive the second signal and the threshold signal and generate a sum A comparison signal related to the protection signal. The system controller of claim 40, wherein the timer and comparator elements further comprise a periodic anti-attack element configured to receive the comparison signal and output the protection signal . The system controller of claim 22, further comprising: a sample and hold component configured to receive the feedback signal and generate the sampled and held signal based on at least information associated with the feedback signal; error An amplifier configured to receive the sampled and held signal and generate an amplified signal based at least on information associated with the sampled and held signal; and a modulating element configured to receive the amplified signal and based at least on The information associated with the amplified signal generates a modulated signal; wherein the drive element is further configured to receive a first signal associated with the modulated signal. A method for protecting a power conversion system, the method comprising: receiving a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system; processing the demagnetization signal and at least based on the feedback signal Information associated with the detected voltage generated by the associated information; generating a protection signal based at least on information associated with the detected voltage and the demagnetization signal; and receiving the protection signal; at least based on being associated with the protection signal Information generating a drive signal; outputting the drive signal to a switch configured to affect a primary current flowing through a primary winding of the power conversion system; wherein: The detected voltage is related to an output voltage of the power conversion system; and the demagnetization signal is related to a demagnetization period of the power conversion system; wherein, for a primary configured to affect flow through the power conversion system The processing of the switching output drive signal of the primary current of the winding includes: if the detected voltage and the demagnetization signal satisfy one or more conditions, outputting the drive signal to cause the switch to open and remain open to protect The power conversion system. A method for protecting a power conversion system, the method comprising: receiving a demagnetization signal generated based at least on information associated with a feedback signal of the power conversion system; receiving and primary current flowing through a primary winding of the power conversion system An associated current sense signal; processing information associated with the demagnetization signal, the current sense signal, and the detected voltage generated based on at least information associated with the feedback signal; based at least on the detected The voltage, the demagnetization signal, and the information associated with the current sense signal generate a protection signal; receiving the protection signal; generating a drive signal based at least on information associated with the protection signal; and being configured to affect flow through a switch of the primary current of the primary winding outputs the drive signal; wherein: the detected voltage is related to an output voltage of the power conversion system; and the demagnetization signal is related to a demagnetization period of the power conversion system; For outputting a switch configured to affect a primary current flowing through the primary winding The processing of the motion signal includes: if the detected voltage, the demagnetization signal, and the current sense signal satisfy one or more conditions, outputting the drive signal to cause the switch to be turned off and remain off to protect The power conversion system.