TWM273771U - Over-power protection apparatus for self-excited power converters - Google Patents

Description

M273771 IX. Description of the new type: [Technical field to which the new type belongs] —A kind of overpower protection device, especially an overpower protection device for self-excited power supply. [Previous technology] Press, in the current desktop computer power supply = widely used, __ whole round _ = source = ❿ electricity = should = self-excitation ^ _ electric tester is the main application circuit μ over power The detection circuit and the -drive C secondary side circuit include-,-bump capacitance =,-upper bridge power transistor Q3, _ upper bridge soil circuit 32, lower bridge power transistor Q4, lower bridge drive circuit 42 and a Blocking capacitor e. There are-output inductor L0,-output capacitor c0, a voltage dividing resistor ^, a voltage dividing resistor: two = device_ and a compensation network, the compensation network includes-compensation power one,! CC; The overpower detection circuit includes a filter diode 22, a chirped wave capacitor CPD, a voltage-dividing resistor Rpi, and a voltage-dividing resistor core 2. The self-excited half-bridge profile supplier has a double hybrid (upper-bridge power transistor Q3 and lower-bridge power transistor q4) as the switching power = off, and uses a self-excited drive square wire to drive the upper-bridge power circuit. The crystal Q3 and the lower transistor q4 'pass the energy from the secondary side to the wheel through the main transformer 1: The self-excitation driving system is _ * with a current transformer hiding crane transformer τ *. This driving method is also called Proportional drive. ^ 7 M273771 β > Kaodi-A Figure ′ shows the power off of the self-excited half-bridge power supply during the start-up period. As shown in the third figure, the self-excited half-bridge type electric reactor sends one of the high-level switching signals M_transistor at start-up ™ controller. The electric voltage VdD passes through a diode 12 and a The resistor RD charges the winding N22B of the driving transformer T2. Because the winding N22B and NιΐΑ have the same polarity, the winding N11A generates a base current ^ on the positive positive surface, and the base current ^ has the amplification characteristic through the power transistor, and correspondingly generates a primary-side current.

Ip = hfex Hitting IB3❿hfe is the current gain of the transistor. The system here refers to the upper-bridge power transistor Q3 〇 Please refer to the second figure B, which is the circuit diagram of the conventional ^ number half-bridge power supply during the energy period. The upper-bridge power transistor is a high-voltage transistor, and its current ′ is small, so it needs a larger base current W to drive. .Driving mode: • Using the driving transformer T2 with current transformer characteristics, and using self-driving method to achieve self-excitation driving. The sensing winding Nρ of the driving transformer D2 is used to detect the primary current of the main transformer 11 Tl. Through the relationship between the number of windings N11A and the sensing winding and the group Nρ · _, we can obtain: Μ / = / vi ^ 乂(1) The winding N11A has a proportional relationship with the sensing winding NP, and the primary side current ιρ flows. • A larger base current IB can be obtained through the sensing winding Np, which also produces a larger primary side. The current Ip, which is similar to the positive feedback mechanism, causes the upper-bridge power transistor Q3 to be completely turned on. As shown in the third figure, the switching signal & at this time is the high 8 M273771 level 'at this time the base current lB3Xhfe > Ip, and the main transformer Tm transfers energy to the output side of the wheel. In addition, because the polarity of the winding n ^ b of the driving transformer I is opposite to that of N⑽, the winding N11B senses a negative potential, and the lower-side power transistor is cut off. Therefore, the primary current flows in the direction from the positive end of the surface capacitor ^ to the upper-bridge power. Transistor a, after

The sense-elevation group of the dynamic transformer $ T2 ⑥ goes to the main relay Tm, and then the blocking capacitor CB is taken back to the zener end of the capacitor C1. The energy at the input end is converted to the output side by the main transformer L. In addition, the sensing winding Np of the driving transformer τ2 can be used to detect the primary-side motor Ip 'and also has the parameters and characteristics of the output current. Therefore, it can be used as a sensing tree to limit the wheel current. (Pole body 22 and filter capacitor CPD) can get the overpower detection voltage:

VPD -VBX (2) NB, is the voltage across the winding NlU or NllB; Nn is the winding N11A or N11B; said = ,,, group N22A or N22b; ZZ β is the upper bridge power transistor ⑦ and the lower bridge power circuit After the input impedance of -q4 is obtained, the overpower detection depends on VpD, and then through the divided voltages Rpi and Rp2, the overpower signal V0P can be obtained. Supply ==: t Ziqiqiao-type power supply circuit diagram of the moon gate. When the PWM controller 100 sends a high accurate voltage m: S2 and Si at the same time, 'Qi and Qi will be turned on and the drive will become w 2. The group N22A_22B will be short-circuited, and the winding Nii ^ n cannot be sensed. 9 M273771 The base that generates the drive The pole current 1B is the same as that of the winding NP. The secondary side power J * p is a cut-off state of the upper-bridge power transistor Q3 and the lower-bridge power transistor Q4. The switching signals & and & It is a low level. At this time, the main transformer cannot transfer energy to the output side. -The second item W refers to the second D figure 'is a circuit diagram of a conventional self-excited half-bridge power supply during energy conversion. When the PWM controller sends out a high-level switching 5-domain Si to turn on the transistor Qi, the driver turns the winding of 2 ^ with the same polarity as-, the winding Nlm senses a positive potential and generates an urgent current IB4. By obtaining a ratio of _11B # _ · Nρ to obtain a larger secret current IB4, the lower-side power transistor% is completely turned on. As shown in the third figure, the switching signal = s4 is the material level. At this time, the pole current lB4xhfe &ip; ip, the main transformer Tm transfers energy to the output side. In addition, 'Because winding N22A and N11A of driving transformer 11 T2 have opposite polarities, winding NllA senses a negative potential', the upper bridge transistor Q3 is turned off, that is, the switching signal S3 is at a low level, and the lower bridge to f crystal Q4 is turned on,- The secondary ^ Ip flow direction is from the positive terminal of the stabilizing capacitor C2 to the blocking capacitor Cb, and passes through the sensing age Np of the main transformer τ_transformer τ2, which is mixed with the lower-end god t crystal Q4 and finally touches the negative terminal of the capacitor Q. The energy at the input is transferred to the output by the main transformer. 2 With the description of the third figure above, the brain of the self-excited half-bridge power supply is known; the controller should be the switching signal S2 as the start signal of the power supply's just started operation. The PWM control m of the bridge-type power supply can also switch positions as the start signal of the electric response word, and the switching signal S2 at this time is a low-level signal. M273771 Please refer to the fourth figure together, which is the circuit diagram of the PWM controller of the conventional self-excited half-bridge power supply. The PWM controller 100 includes a pulse width modulation unit 110, an error amplifier 120, a comparator 130, and a timer 14o. The pulse width modulation unit 110 further includes two D-type flip-flops 1101 and 1102, a single-exhaust device 1103, double-reverse and gates 1104 and 1105, and a comparator 1106. The oscillator 1103 is used to generate a sawtooth wave signal VSAW and a clock signal CLK. The sawtooth wave signal v saw can determine the switching frequency of the switching signals Si and S2; the positive terminal of the error amplifier 12o is connected to a reference voltage VR, The negative terminal is connected to the feedback terminal FB, which receives a feedback signal vFB to output a compensation signal VcOM; the positive and negative terminals of the comparator 1106 are respectively connected to the output terminal of the error amplifier 120 and the The oscillator 1103 receives the compensation signal Vc0m and the sawtooth wave signal VSAW, and outputs the result after a comparison operation, and then passes through the D-type flip-flops 1101, 1102, and the reverse gates 104, 11. The logic operation of 5 is to output and determine the pulse widths of the switching signals S! And S2. Based on safety considerations, the power supply must provide an over-power protection circuit to limit the power output to protect the power supply itself and the power system end, to avoid short-circuit and overload misoperation. When the output terminal of the power supply is short-circuited and overloaded, the output current and power will increase greatly. The parameters and characteristics of the output current-the pick-up current Ip also increase, and the over-signal v0p will increase by 0. When the over-power signal V0p exceeds the critical signal Vt, through the comparison operation of the comparator 130, the output of the comparator 130 and the reset terminal of the timer 14 are at a high level. At this time, the timer 140 starts counting and a delay After the time Td, the output terminal of the timer 14 will send a high-level latch signal LATCH, which passes through the pWM controller's internal 11 M273771 •, Pa Pa knowledge switch signal & and S4 are completely cut off. In order to avoid the malfunction caused by the instantaneous load change, the delay time d must be greater than the reaction time of the dynamic negative cut. When the output terminal of Tiantian Power Supply Co., Ltd. is short-circuited, the output voltage V0 decreases, and the feedback signal Vfb received by the feedback terminal FB decreases. Since the reference voltage is repeatedly a fixed voltage, the feedback signal VFB is between the reference voltage Vr The voltage difference is too large, so the feedback signal) FB 'and the test voltage VR will output a large compensation signal% 〇_ to the comparator 1106, which is the compensation signal, after the error amplification H 12〇. vCOM increased to Vcom ^. When the power supply is overloaded, the output power increases, and the compensation signal VC0M also increases to Vc0_. After the compensation signal v_ (A) and the mineral tooth wave signal VSAW are compared with the output of the comparison operation of G Cong, after the logical operation of the d-type flip-flop 110, 1102, and the inverse gates 1104, 1105, the switching signal Si will be output. (A) and S2⑷. As shown in the third figure, it can be seen that the pulse widths of the switching signals () and S2 (A) are smaller than the pulse widths of S1 and Lu S2. This will produce switching signals with larger pulse widths ^ and S4 (A > This will increase the duty cycle of the power transistors Q3 and Q4, and at the same time, the waveform of the voltage vT1 across the main transformer D1 will change to V ·, and the duty cycle of the voltage vT1 (A) across the main transformer D1 is greater than vTl. The work cycle, this situation will continue to the end of this delay time Td. In this view, the late coffee Td will make money and power protection difficult to control, and the components that rely on and supply must withstand large pressure and current stress, which can easily cause For this reason, the author proposes a self-excited surface power supply over-power protection device in response to the above problems. Therefore, the self-excitation power supply rides over-power protection ^ 12 M273771. Current control and periodic current limitation to solve the above problems. [New content] The main purpose of this creation is to propose—a kind of over-power protection device for self-excited power supply. Short circuit at the terminal, During overload, the power cycle of the upper and lower bridge power transistors is reduced by reducing the compensation signal to achieve periodic current limiting and output power limitation. The overpower protection device of the self-excited power supply of this creation includes There is a # flexible start unit that receives a feedback signal from one of the self-excited power supplies and generates a compensation signal for the pulse width modulation unit of one of the self-excited power supplies to generate a switching signal, and the switching signal controls the self-excited power supply In addition, the flexible start-up unit is connected to the acid unit, and the entire unit receives the -over-power domain and-the second critical signal of the self-excited t-source supplier, and a short-circuit occurs at the output end of the self-excited source. And overload, and when the overpower signal is greater than the second critical signal, the adjustment unit drives the flexible start unit, which in turn drives the pulse width modulation unit to modulate the switching signal _. A timing unit, which receives the overpower signal and —The first—critical signal. When the overpower signal is greater than the —critical signal, the timing unit counts. After counting for a period of time, it will send out the -pickup lock signal. The self-excited power supply has stopped supplying power. In order to make your reviewing committee more 'progressive—with regard to the structural characteristics and effects achieved by this creation, I would like to implement it and cooperate with detailed instructions and explanations. As follows: 13 M273771 [Embodiment] Refer to the fifth figure, which is the circuit diagram of the PWM controller of the self-excited power supply for this creation; the over-power protection device of this creation can be set for the self-excited power supply. A PWM controller 200, which is connected to a PWM width control unit tl210 of the pwM controller 200. The overpower protection device of this creation may not be provided in the pWM controller 200. The overpower protection device of this creation includes a A flexible starting unit 22, a timing unit το 230, and an adjustment unit 240. The flexible starting unit 22 includes an operational amplifier _ big state 2201, an error amplifier 2202, a clamping diode 2203, and a charging unit for charging. The unit includes a first power source 2204 and a startup capacitor Css. The first power source 2204 is connected to the startup capacitor Css to charge the startup capacitor Css. The positive terminal of the operational amplifier 2201 receives a reference voltage Vr, and the negative terminal is connected to the output terminal of the operational amplifier 2201 and the startup capacitor Css as a unity gain buffer state, and then the startup voltage Vss is output at the output terminal of the operational amplifier 2201. At the time, the voltage stabilizing system is a voltage stabilizing unit; the error amplifier 222, whose positive terminal is connected to the startup power valley Css and the output terminal of the operational amplifier 2201, receives the startup voltage Vss, and the negative terminal of the error amplifier 2202 is The feedback terminal FB connected to the self-excited power supply receives the feedback signal VFB. The output of the error amplifier 2202 is connected to the pulse width modulation unit 210. The error amplifier 2202 receives the starting voltage Vss and the feedback signal VFB. It is used to output the compensation signal vCOM; the clamp diode 2203 is connected between the negative terminal and the output terminal of the error amplifier 2202. It is used to clamp the voltage of the compensation signal VCOM when the self-excited power supply starts. Level. Pulse width modulation unit 210, which includes two d-type flip-flops 2101 and 2102, an oscillator 2103, two invertors and gates 2104 and 2105, and a comparator 2106. The oscillator M273771 and the device 2103 are used to generate a clock signal CLK. A sawtooth wave signal vSAW can be used to determine the switching frequency of the switching signals Si and S2; the positive terminal of the comparator 2106 is connected to the output terminal of the error amplifier 2202 of the flexible start unit 220, and receives the compensation signal VCM, while the negative terminal It is connected to the oscillator 2103, receives the sawtooth wave signal vSAW, and outputs the result after the comparison operation, and then through the logical operation of the D-type flip-flops 2101, 2102 and the inverse gates 2104, 2105, and outputs and determines the switch The pulse width of the signal & and &.

When the self-excited power supply starts at the moment of startup, the first power source 2204 will charge the startup capacitor css, and the startup voltage vss starts to rise from zero volts. Since the operational amplifier 2201 is a unity gain buffer, the normal state is entered when the maximum value of the startup amplifier is the reference voltage vR. Initially, when the positive end of the error amplifier 2202 is zero volts, the output of the error amplifier will be clamped at the clamp diode 2203 because the village-pole 22G3 has a voltage level of _. After decreasing% (usually about 0.7V), the starting voltage% received at the positive terminal of the error amplifier gradually rises, and the compensation signal I output by the error amplifier 2202 also gradually increases. In this way, when the contact is filled, the Si and & amp The pulse width will change as the start voltage Vss changes. The start voltage Vss reaches the reference voltage%. At this time, the pulse widths of the switching signals Sl and & reach the preset value, and the wheel of the self-excited power supply is lighter. V. It will increase as the starting voltage Vss gradually rises, and finally the output voltage V0 is fully established, thus achieving the effect of flexible starting. The private owner of the power supply 22G4 is the electrical surface, which is used to provide the charging current to the starting capacitor Css when the self-excited power supply starts up, so that the starting voltage Vss gradually rises, so that the output voltage of the self-excited power supply 乂 0 gradually increase. The starting capacitor Css is 15 M273771 • * The cost of the fine self-excitation type electric response n should be controlled by the capital, larger = dynamic, the capacity of the css will increase the time, and can be low. _ Voltage and electricity == Therefore, the delay time caused by the capacitance of the capacitor 启动 can be within a proper range. With reference to the first figure, and referring again to the fifth figure, the timing unit 23o includes a first comparator 2301 and a timer fiber. The positive and negative ends of the first comparator 2301 have received the power signal V. P and the -threshold signal & while the first comparison cry 2301 is connected to the reset terminal of the timer. When the overpower signal V0P is lower than the first critical signal vTH1, the output of the first-comparator 23G1 and the reset terminal of the timer fiber are at a low level. At this time, the number of timers and the output terminal of the timer fiber The latch signal LATCH sent is at a low level, and the self-excited power supply operates normally. '、 When the output terminal of the self-excited power supply is short-circuited or overloaded, the output current and power increase greatly, the parameters of the output money and the secondary-side power ^ Lu f also: t Yuejia further causes an over power signal v 〇p increased. When the overpower signal v〇p exceeds the -threshold signal VTH1, the first-comparison between the output end of the n fiber and the reset end of the timer is at a high level. 'At this time, the timer starts to count, after a delay time Td' The latch signal LATCH sent from the output of the timer 23〇2 is at a high level. Through the protection circuit inside the PWM controller, the upper-side power transistor and the lower-side power transistor Q4 are completely cut off. Passing energy to the output side means that the self-excited power supply stops supplying power. ★ Refer to the fifth figure again. The adjustment unit includes a second comparator, a second power supply 2402, and a -th switch platform. The positive and negative ends of the second comparator surface and the M273771 end respectively receive the power signal vOP and the first. The second critical signal VTm; the second power source 2402 is connected between the first switch 2403 and a ground terminal, and the first switch% is connected to the first power source 2204 and the startup capacitor css. Similarly, when the output end of the self-excited power supply is short-circuited or overloaded, the overpower signal VOP increases. When the overpower signal v0p exceeds the first critical signal, the timer 2302 will start counting. If the overpower signal v When 〇p also exceeds the second critical signal, after the comparison operation of the second comparator 2401, the _ output terminal of the second comparator 2401 is at a high level, which drives the first switch 2403 to be in an on state, and the startup capacitor Css is fixed. Plutonium's first power source 2402 starts to discharge. Although the first power source 2204 still charges the starting capacitor css, the discharge current value 1μ of the second power source 2402 is much larger than the charging current value IGH ′ of the second power source 22G4, thus causing the discharge voltage Vss to discharge relatively quickly as shown in the sixth figure. . Since the self-excited power supply must have a slight delay through feedback, as shown in the sixth figure, when the overpower signal V0p exceeds the second critical signal VtH2, it will continue to be stable for a short period of time. At this time, the startup voltage Vss The timer 23〇2 is still counting. Relatively speaking, because the starting voltage vss drops, the error amplifier 22 02 outputs the compensation signal Vco_ as shown in the seventh figure. The level of the compensation signal ν_⑼ can be seen from the figure. The level is smaller than the compensation signal vC0M, so after the comparison operation of the comparator 2106, the gates 2104 and 2105 will be reversed, and the switching signal with a larger pulse width and S2⑼ will be output, thereby generating a smaller pulse width. The switching signal heart and ⑼, causes the duty cycle of the upper-bridge power transistor Q3 and the lower-bridge power transistor a to decrease, and reduces the duty cycle of the voltage VT_ across the main transformer, so that the overpower signal v decreases from 0 17 M273771

When the overpower minus vGPlr_ is lower than the second critical minus percentage, the discharging operation of the startup capacitor css ends, and the startup voltage ~ is maintained at a lower voltage level f. At this time, because the overpower signal Vqp is still higher than the first critical signal v plus, the timing is 2302 and it is also counting. When the second critical signal VTH2 is turned off under the overpower city Vqp, the second comparator 2401 is disabled. The first Guanhu is in the cut-off state. At this time, the '-th power supply 22G4 starts to charge the startup capacitor Css again, and then the startup voltage vss starts to rise slowly from a lower voltage level. The slow rise of the starting voltage Vss causes the duty cycle of the upper-bridge Shendian crystal Q3 and the lower-bridge Shendian thread Q4 to increase slowly ', causing the overpower domain Vqp to exceed the second critical signal VTH2 again. Then, the output of the second comparator 2401 is at a high level, the first switch lake is in the on state, and the second power supply fiber that starts the capacitor Css starts to discharge again, so the charging and discharging operation is repeated until- After the delay time I, when will the latch-up message sent by the output terminal of the 2302 steal? The latch is at a high level. After PWM control, the internal circuit will make the upper power transistor and the lower power transistor Q4 completely. cutoff. When the output terminal of the self-excited power supply is short-circuited, the output voltage Vo decreases, the feedback signal VpB received by the feedback terminal FB decreases, and the compensation signal VcOM also increases. When the self-excited power supply is overloaded, the output power increases and the compensation signal 乂 _ also increases. Excerpted from the increase in the holy hoof from the identification of E, and through the start of the capacitor Css to reduce the start double ~, so that the error amplifier ^ 2202 output smaller compensation E to the comparator genus, that is = compensation Signal Vc: The age is Ve_). _Alkali v_Hawker tooth wave signal V. Logic vehicle with comparator dove, D-type flip-flop 2⑼, fiber and antimony, No. 18 M273771 '_generating smaller pulse width_change signal & ⑻ and, The duty cycle of the upper-bridge power transistor q3 and the lower-bridge power transistor Q4 is reduced ^ The work talk of Vt_ at both ends of the main transformer Tl is reduced, and the delay time Td ends. As the power protection mechanism has been activated during this delay time Td, the current limit and the maximum power output limit at the same time. The over power protection 3 created by this creation is free. When the output terminal of the self-excited power supply H is short-circuited and overloaded, the compensation signal VcOM, which is too high, is used to increase the output power of the self-excited power supply: When using this creation, the voltage and current ratings of the upper bridge power transistor Q3 and the lower bridge power transistor 仏 can be lowered, and the circuit cost can be reduced. Referring again to the fifth figure, the adjusting unit 24o further includes a second switch 2 connected to the starting capacitor Css and the ground terminal, and the second switch 2 connected to the starting capacitor Css in parallel. With Eolin, the ribs discharge the starting capacitive core. When the self-excited power supply does not provide output power, the authoring unit 220 detects the feedback signal VpB from the feedback FB and passes through the pwM controller 200. [5's compliance circuit is used to output the reset signal. The activation of the reset signal rudder can cause the startup capacitor Css to be discharged quickly, so that the startup voltage Vss can be quickly reduced, which in turn causes the level of the compensation signal vCOM to drop. One is because the compensation signal is reduced quickly. After the compensation signal VCGM and the spur tooth signal Vsaw are compared with the comparator dove, the switching signal that causes the output of a very small pulse width will cause the upper bridge power transistor Q3 and the lower bridge. The duty cycle of the power transistor A is reduced, that is, the duty cycle of the voltage VT1 across the main transformer 1 is reduced. When the starting voltage Vss continues to drop, and the surface signal 乂 _ also drops below the ore tooth wave ^ 19 M273771 ^ 'transistor Ql and Q2 are fully turned on, the upper bridge power transistor & and the lower bridge power transistor q4 are almost Completely drum, due to shouting reset Langdon touch protection. In summary, this creation proposes a kind of over-the-top recording, which is used for self-excitation. ^ Power supply materials. When the wheel _ short circuit and make up _, you can adjust the starting county on the starting capacitor by adjusting = , Called low-compensation signal, so the duty cycle of the bridge power transistor and the lower bridge power transistor is reduced, and

2 The cycle of the two ends of the repeater depends on the cycle, so that the periodic current limit and the maximum output power limit can be achieved. The above-mentioned ones are "only for this creation—the preferred embodiment, not for limiting the scope of this creation". Therefore, all the shapes, structures, features, and spirits described in this patent creation patent are all light. Changes and modifications are included in the scope of the patent application for this creation.

20 M273771 [^ Schematic description] =-The diagram is the circuit diagram of the conventional self-excited half-bridge power supply; 'Bu attached 纟 is the circuit diagram of the $ 激 self-excited ^ half-bridge power supply during startup; The first diagram B is a circuit diagram of a conventional self-excited half-bridge type electric duty during energy conversion; the second diagram C is a circuit diagram of a conventional self-excited half-bridge type t source during the supply of a flywheel; Figure D is the circuit diagram of the conventional self-excited half-bridge power supply during the energy conversion period. The second diagram is the duty wave signal, compensation signal, switching signal and main signal of the conventional self-excited half-bridge power supply. The waveform diagram of the voltage across the transformer. The fourth diagram is the circuit diagram of the pWM controller of the conventional self-excited half-bridge power supply. The fifth diagram is the circuit diagram of the pWM controller of the self-excited power supply. The sixth diagram is the waveform diagram of the startup voltage vss and the overpower signal νΟΡ of the overpower protection device of the self-excited power supply; and the seventh diagram is the sawtooth wave signal of the self-excitation power supply of this creation , Compensation signal, switching signal and main transformer Waveform diagram of the voltage across. [Description of main component symbols] 12 Diodes 22 Filtering Diodes 21 M273771 32 High-side drive circuit 42 Low-side drive circuit 100 PWM controller 110 Pulse width modulation unit 1101 D-type inverter 1102 D-type inverter 1103 Oscillator 1104 Inverter 1105 Inverter 1106 Comparator 120 Error amplifier 130 Comparator 140 Timer 200 PWM controller 210 Pulse width modulation unit 2101 D-type inverter 2102 D-type inverter 2103 Oscillator 2104 Gate 2105 and Gate 2106 Comparator 22 M273771

220 Flexible starting unit 2201 Operational amplifier 2202 Error amplifier 2203 Clamping diode 2204 First power supply 230 Timing unit 2301 First comparator 2302 Timer 240 Adjustment unit 2401 Second comparator 2402 Second power source 2403 First switch 2404 Second Switch C. Output capacitor C! Stabilizing capacitor C2 Stabilizing capacitor CB Blocking capacitor Cc Compensation capacitor Cpd Filter capacitor Css Start capacitor CLK Clock signal 23 M273771

Ib base current Ip primary current N11A winding Nub winding N22A winding N22B winding NP sensing winding Qi transistor q2 transistor Qb upper bridge power transistor Q4 lower bridge power transistor LO output inductor R〇i voltage divider resistor R 2 Voltage-dividing resistor Rc Compensation resistor Rd Resistor Rpi Voltage-dividing resistor Rp2 Voltage-dividing resistor Si Switching signal Si (A) Switching signal Sl (B) Switching signal 24 M273771

S2 Switching signal S2 (A) Switching signal ^ 2 (B) Switching signal S3 Switching signal S3 (A) Switching signal S3⑼ Switching signal S4 Switching signal ^ 4 (A) Switching signal ^ 4 (B) Switching signal Tl Main transformer T2 Drive Transformer Vc〇M Compensation signal Vc〇M (A) Compensation signal Vc〇M (B) Compensation signal Vdd Power supply voltage Vfb Feedback signal VPD Overpower detection voltage V〇 Output voltage V〇p Overpower signal VR Reference voltage Vs AW Sawtooth Wave signal Vss start voltage 25 M273771 ντ critical signal 'VTi voltage across the main transformer Vti (a) voltage across the main transformer Vti (b) voltage across the main transformer Vthi first critical signal VtH2 second critical signal

26

Claims (1)

M273771 10. Scope of patent application: 1. An overpower protection device for a self-excited power supply, including:-Flexible start-up single 7C, receiving the self-excited power supply-feedback signal, generating-compensating signal ' For the self-excited power supply-the pulse width modulation single switching signal 'the switching signal controls the self-excited power supply to turn out: power; the light unit is activated, and the difficult unit receives the self-excited power supply When the H-overpower signal and the second critical signal are supplied, and when the overpower flood is greater than the second critical signal, the adjustment unit drives the flexible start-up unit, which in turn drives the pulse width modulation unit to modulate the switching signal, To reduce the output of the self-excited power supply; and a timing unit to receive the over-power signal and a first critical signal of the self-excited power supply, and when the over-power signal is greater than the first critical signal, the The timing 丨 unit counts. After counting for a period of time, it will send a latch signal to make the self-excited power supply stop supplying power. 2. The over-power protection device of the self-excited power supply as described in the first item of the patent scope of the patent, wherein the flexible starting unit further includes: a charging unit that generates a starting voltage; a voltage stabilizing unit that is coupled The charging unit is used to stabilize the voltage; an error amplifier whose positive terminal is coupled to the charging unit and the voltage stabilizing unit receives 27 M273771 4 starting voltage, and the negative terminal of the differential amplifier receives the self-excited power supply In response to this feedback, the output wheel of Weichai Amplifier II is woven between the output terminal and the negative terminal of the error amplifier with a _compensation signal ^ and a -diode. 3. The overpower protection device of the self-excited power supply as described in item 2 of the scope of the patent application, wherein the voltage stabilizing unit may be a unity gain buffer unit, which may be an operational amplifier. The positive terminal receives the reference voltage. The negative end of the operational amplifier is connected to the output terminal and the charging unit to receive the start voltage. The operational amplifier is connected to the positive terminal of the error amplifier. 4. The overpower protection of the self-excited power supply device described in item 2 of the scope of the patent application, wherein the charging unit includes a first power source and a starting capacitor, and the first power source is reduced to the starting capacitor. _Enable capacity and generate this starting voltage. Xin 5. The overpower protection device of the self-excited power supply as described in the second item of the patent application of Shenying, wherein the flexible starting unit is used to drive the flexible start unit, and then the pulse width modulation unit is used to modulate the switching signal. The adjustment unit includes: a brother, a power source, connected to a ground terminal;-the -th between the switch charging unit and the second series; and the-comparison is' the positive and negative terminals respectively receive The over-power of the self-excited power supply is the critical signal of tiger and hybrid two, the over-power signal is greater than the second 28 M273771. The critical signal is skewed 'the output of the output of the second comparator-E, driving the first -Plane conduction 'enables the charging unit to be charged and reduces the starting voltage. 6. The overpower protection device of the self-excited power supply device according to item 5 of the scope of patent application, wherein the adjustment unit further includes a second switch, which is lightly connected between the charging unit and the ground terminal, The second switch is turned on by receiving a reset signal, so that the charging unit is discharged, and the starting voltage is reduced. Call 7. If the scope of patent application is the first! The overpower protection device of the self-excited power supply device described in the above item, wherein the timing sheet $ includes a first comparator and a timer, the first comparator is coupled to the timer, and the first comparator The positive terminal and the negative terminal receive the overpower signal and the first critical signal of the self-excited power supply respectively. When the overpower signal is greater than the first critical signal, the first comparator outputs a high level signal to The timer causes the timer to count. 8 · The overpower protection of the self-excited power supply as described in item 1 of the scope of the patent application • Device 'where the overpower signal received by the adjustment unit is greater than the second critical signal, the adjustment unit drives the flexible startup Unit to reduce the level of the compensation signal to reduce the output of the self-excited power supply. 9. The overpower protection device of the self-excited power supply as described in item 1 of the scope of patent application, which is a PWM controller that can be installed in one of the self-excited power supplies. 29