CN207083021U

CN207083021U - The multistage loop control circuit of primary side feedback Switching Power Supply

Info

Publication number: CN207083021U
Application number: CN201720860324.1U
Authority: CN
Inventors: 励晔; 黄飞明; 赵文遐; 朱勤为; 吴霖
Original assignee: WUXI SI-POWER MICRO-ELECTRONICS Co Ltd
Current assignee: WUXI SI-POWER MICRO-ELECTRONICS Co Ltd
Priority date: 2017-07-14
Filing date: 2017-07-14
Publication date: 2018-03-09
Anticipated expiration: 2027-07-14

Abstract

The utility model provides a kind of multistage loop control circuit of primary side feedback Switching Power Supply, including：Sampling and keep module, base modules, error amplifier, loop control unit, cable voltage-drop compensation module, current source, peak point current comparator, drive circuit, latch；The input of sampling and keep module is used for the feedback signal of sampled representation transformer-secondary voltage and holding；The inverting input of the output termination error amplifier of sampling and keep module, the output end of the homophase input termination base modules of error amplifier, the input of the output termination loop control unit of error amplifier；Loop control unit includes fast loop, at a slow speed loop and DC loops；The change of voltage is mended in the change of the switching frequency of fast loop controlling switch power supply, the change of the peak current threshold of slow loop way control switch power supply, the imbalance of DC loop control errors amplifiers, the output line of Switching Power Supply；The utility model can solve the contradictory problems such as fast dynamic response, the stability of a system.

Description

The multistage loop control circuit of primary side feedback Switching Power Supply

Technical field

Inverse-excitation type switch power-supply control technology field is the utility model is related to, especially a kind of primary side feedback Switching Power Supply is more Rank loop control circuit.

Background technology

Inverse-excitation type switch power-supply is widely used because its application structure is simple and cost is relatively low.Primary side feedback control technology Loop modulation is carried out to isolate sampling primary side output voltage signal without optocoupler and TL431, therefore application is simpler, into This is lower, is widely used in middle low power field of switch power.

With the continuous improvement of electronic product performance, start output dynamic response and the output voltage ripple to Switching Power Supply Requirements at the higher level are proposed etc. index.Wherein export dynamic response and output ripple the two indexs contradiction each other in itself, low output electricity Embossing ripple needs system loop frequency response to have larger phase margin, and larger phase margin can reduce the dynamic of system Response, the contradiction of the two indexs are particularly evident in primary side feedback Switching Power Supply.In addition, electronic equipment performance enhancement also causes Switching Power Supply output load current is continuously increased, and this can produce significant cable pressure drop in output cord, and this needs to switch electricity Compensated inside source chip, to ensure line end output voltage relative constancy.

The primary side feedback Switching Power Supply of main flow is controlled using low order single loop at present, that is, passes through switching power control system Middle unitary variant to control the DC quantities such as output dynamic response, output voltage ripple and line benefit amount simultaneously, and this easily causes system Loop is unstable, or index of correlation is difficult to meet design requirement, or needs extra increase system cost.

The content of the invention

The purpose of this utility model is to overcome the deficiencies in the prior art, there is provided a kind of primary side feedback Switching Power Supply Multistage loop control circuit, system loop is resolved into fast loop, at a slow speed loop and DC loops, it is different in control loop respectively Variable parameter, to solve the contradictory problems such as system fast dynamic response, the stability of a system, simplify system design.The utility model The technical scheme of use is：

A kind of multistage loop control circuit of primary side feedback Switching Power Supply, including：Sampling and keep module, base modules, error Amplifier, loop control unit, cable voltage-drop compensation module, current source, peak point current comparator, drive circuit, latch；

The input of sampling and keep module is used for the feedback signal of sampled representation transformer-secondary voltage and holding；

The inverting input of the output termination error amplifier of sampling and keep module, the homophase input termination of error amplifier The output end of base modules, the input of the output termination loop control unit of error amplifier；

Loop control unit includes fast loop, at a slow speed loop and DC loops；The switch of fast loop controlling switch power supply The change of frequency, the S inputs of the output termination latch of fast loop；The peak point current threshold of slow loop way control switch power supply The inverting input of the change of value, at a slow speed the output termination peak point current comparator of loop；DC loop control errors amplifiers The change of voltage, the output end wiring cable voltage-drop compensation module of DC loops are mended in imbalance, the output line of Switching Power Supply, and cable pressure drop is mended Repay module and connect current source, the output of current source connects the input of sampling and keep module；

The R input of latch connects the output end of peak point current comparator, and the Q output of latch connects the defeated of drive circuit Enter end, the drive end of the output end of drive circuit as multistage loop control circuit；The in-phase input end of peak point current comparator Primary current sampling feedback end as multistage loop control circuit.

Further, fast loop includes PWM comparators, sawtooth signal generator；The homophase input termination of PWM comparators The output end of sawtooth signal generator, anti-phase input terminate the output end of error amplifier, and the output termination of PWM comparators latches The S inputs of device；

Loop includes amplitude limit follower, first switch capacitance network, peak point current base modules at a slow speed；Amplitude limit follower The output end of input termination error amplifier, the input of output termination first switch capacitance network, first switch capacitance network Output termination peak point current base modules input, the output of peak point current base modules connects the anti-of peak point current comparator Phase input；The output signal of error amplifier passes through amplitude limit follower, and the error signal after maximin is limited inputs Integral iteration is carried out to first switch capacitance network；

DC loops include second switch capacitance network, and the signal after first switch capacitance network integrates is electric by second switch Content network carries out integral iteration.

Specifically, first switch capacitance network includes electric capacity C222, C223 and electric-controlled switch K224；Electric capacity C222 one end Connect the output end of amplitude limit follower and electric capacity C223 one end is connect by electric-controlled switch K224, electric capacity C223 one end is as first The output end of switched capacitor network；Electric capacity C222 and the C223 other end connect primary ground.

Further, first switch capacitance network carries out an integral iteration in each PWM switch periods.

Specifically, second switch capacitance network includes electric-controlled switch K231 and K232, electric capacity C233, C234；Electric-controlled switch The output end of a K231 termination first switch capacitance network, another termination electric-controlled switch K232 one end and the one of electric capacity C233 End, the electric capacity C233 primary ground of another termination；Electric-controlled switch K232 another termination capacitor C234 one end and connection cables pressure Compensating module drops；The primary ground of electric capacity C234 another termination.

Further, it is narrow pulse signal reverse each other to switch K231 and K232 control signals, by first switch electricity Signal after content network integration transmits signal by switching K231 and K232 Cycle by Cycle to electric capacity C233 and C234, and a PWM is opened Close cycle transmission once.

Further, loop has identical DC current gain with fast loop at a slow speed；At a slow speed loop-three dB bandwidth ratio Fast loop is small, and the frequency response of loop at a slow speed is less than the frequency response of fast loop；

DC loops have identical DC current gain with loop at a slow speed；DC loops-three dB bandwidth is smaller than loop at a slow speed, DC rings Frequency response of the frequency response on road less than loop at a slow speed.

More preferably, the both ends parallel connection that K232 is switched in first switch capacitance network both ends and second switch capacitance network adds Fast branch road；It is described to accelerate branch road to include the opposite diode of two polar orientations in parallel.

The utility model has the advantage of：Multistage loop control provided by the utility model optimize fast dynamic response and The contradiction of loop stability, while fast dynamic response is lifted, also improve the stability of a system and system output accuracy；This Utility model can be greatly simplified system application and design and reduce system peripherals cost.

Brief description of the drawings

Fig. 1 is electrical schematic diagram of the present utility model.

Fig. 2 is the electrical schematic diagram of loop control unit of the present utility model.

Fig. 3 is multistage loop response schematic diagram of the present utility model.

Fig. 4 is loop at a slow speed of the present utility model and DC loop response acceleration principle figures.

Embodiment

With reference to specific drawings and examples, the utility model is described in further detail.

Fig. 1 is a kind of primary side feedback inverse-excitation type switch power-supply（Hereinafter referred to as Switching Power Supply）Schematic diagram, the Switching Power Supply Include the multistage loop control circuit 120 of primary side feedback Switching Power Supply of the present utility model（Hereinafter referred to as multistage loop control electricity Road 120）, and appropriate peripheral cell；

In the Switching Power Supply, input rectifying bridge, bus direct current are mainly formed by diode D101, D102, D103, D104 Hold C105 mainly to strobe；The output end of transformer T106 primary different name termination rectifier bridge, primary termination power of the same name Switching tube N1 drain electrode, switching tube N1 source electrode connect primary sampling resistor Rcs one end, the primary sampling resistor Rcs other end Connect primary ground；Transformer T106 secondary terminating diode D105 anodes of the same name, diode D105 negative electrode is as Switching Power Supply Positive output end, the negative output terminal of transformer T106 secondary different name end as Switching Power Supply；Electric capacity C3 and resistance R3 are connected in parallel on Between the positive and negative output end of Switching Power Supply；Diode D105, electric capacity C3 and resistance R3 form output rectification filter component 107；Auxiliary After the voltage of winding is by two divider resistance R1 and R2 partial pressures, as the feedback signal 108 for representing secondary voltage；

Multistage loop control circuit 120 includes sampling and keep module 121, base modules 122, error amplifier 123, loop Control unit 124, cable voltage-drop compensation module 125, current source 126, peak point current comparator 130, drive circuit 131, latch Device 132；

The input of sampling and keep module 121 is used for the feedback signal of sampled representation transformer-secondary voltage and holding；Its By transformer secondary coil and the coupled relation of ancillary coil, in transformer T106 demagnetization phases, from ancillary coil sampling table Show the feedback signal 108 of secondary voltage and keep；The output of sampling and keep module 121 terminates the anti-phase defeated of error amplifier 123 Enter end, the output end of the homophase input termination base modules 122 of error amplifier 123, the output termination ring of error amplifier 123 The input of road control unit 124；

The sampling that sampling and keep module 121 exports keeps signal to be inputted for the negative-feedback of error amplifier 123, and sampling is kept Signal handles with reference voltage signal by error amplifier 123, and output error signal judges loop adjustment direction, works as output Error signal uprises, and represents that output loading aggravates, and when output error signal step-down, represents that output loading lightens；

Loop control unit 124 includes fast loop 210, at a slow speed loop 220 and DC loops 230, and they have identical Low-frequency gain and different cut-off frequencies；The frequency response speed of fast loop by error amplifier 123 frequency response speed Determine, the response speed of loop and DC loops is determined by switching frequency and capacitance ratio at a slow speed；

The switching frequency of the controlling switch power supply of fast loop 210（That is working frequency）Change, the output of fast loop 210 Terminate the S inputs of latch 132；The change of the peak current threshold of the controlling switch power supply of loop 220 at a slow speed, at a slow speed loop The inverting input of 220 output termination peak point current comparator 130；The imbalance of the control error amplifier 123 of DC loops 230, The output line of Switching Power Supply mends the change of voltage, the output end wiring cable voltage-drop compensation module 125 of DC loops 230, cable pressure drop Compensating module 125 connects current source 126, and the output of current source 126 connects the input of sampling and keep module 121；

The R input of latch 132 connects the output end of peak point current comparator 130, and the Q output of latch 132 connects drive The input of dynamic circuit 131, the drive end of the output end of drive circuit 131 as multistage loop control circuit, is opened for connecting Close pipe N1 grid；The in-phase input end of peak point current comparator 130 samples as the primary current of multistage loop control circuit Feedback end, for connecting primary sampling resistor Rcs；

As shown in Fig. 2

Fast loop 210 includes PWM comparators 213, sawtooth signal generator 212；The homophase input of PWM comparators 213 The output end of sawtooth signal generator 212 is terminated, anti-phase input terminates the output end of error amplifier 123, PWM comparators 213 Output termination latch 132 S inputs；

The output signal 211 of error amplifier 123 is modulated with serrated signal by PWM comparators 213, produces PWM Signal control power switch pipe N1 switch；The output signal 214 of PWM comparators 213 carries out set to latch 132, and its is defeated Go out signal and power switch pipe N1 is driven after overdrive circuit 131, until the output reset latch of peak point current comparator 130 132, power switch pipe N1 are turned off, and wait next switch periods；The height of the signal link controlling switch power work frequency Change, fast loop is controlled for system；

Loop 220 includes amplitude limit follower 221, first switch capacitance network, peak point current base modules 225 at a slow speed；Limit The output end of the input termination error amplifier 123 of width follower 221, the input of output termination first switch capacitance network, The input of the output termination peak point current base modules 225 of first switch capacitance network, peak point current base modules 225 it is defeated Go out to terminate the inverting input of peak point current comparator 130；

Wherein first switch capacitance network includes electric capacity C222, C223 and electric-controlled switch K224；Electric-controlled switch K224 is controlled In narrow pulse signal；The output end of an electric capacity C222 termination amplitude limit follower 221 simultaneously connects electric capacity by electric-controlled switch K224 C223 one end, the output end of electric capacity C223 one end as first switch capacitance network；Electric capacity C222 and the C223 other end Connect primary ground；

The output signal 211 of error amplifier 123 by amplitude limit follower 221, maximin be limited after error Signal is input to the first switch capacitance network being made up of electric capacity and switch and carries out Integral Processing, and each PWM switch periods is entered Integral iteration of row；Signal after first switch capacitance network integration produces peak value electricity by peak point current base modules 225 Reference voltage is flowed, compared with the pressure drop on primary sampling resistor Rcs, produces power switch pipe N1 cut-off signals；Slow loop Road 220 has identical DC current gain with fast loop 210；The frequency response of loop 220 is decided by capacitance ratio and opened at a slow speed Frequency is closed, its frequency response is less than the frequency response of fast loop 210；The peak value electricity of the controllable switch power supply of loop 220 at a slow speed The size of stream；Link where first switch capacitance network constitutes system loop at a slow speed；

Specifically, by amplitude limit follower 221, output violent change signal passes through the output signal 211 of error amplifier 123 Electric capacity C222 is preserved, and switchs K224 connection electric capacity C222 and C223, of short duration in a switch periods to turn on once, electric capacity C222 and electric capacity C223 do an integral operation in switch K224 ON times, realize signal on electric capacity C222 to electric capacity C223 is transmitted；After signal on electric capacity C223 is by the voltage division processing of peak point current base modules 225, produces signal 226 and be used as peak It is worth the reference voltage of current comparator 130.

DC loops 230 include second switch capacitance network, specifically include electric-controlled switch K231 and K232, electric capacity C233, C234；The output end of an electric-controlled switch K231 termination first switch capacitance network, another termination electric-controlled switch K232 one end With electric capacity C233 one end, the electric capacity C233 primary ground of another termination；The one of electric-controlled switch K232 another termination capacitor C234 Hold simultaneously connection cables voltage-drop compensation module 125；The primary ground of electric capacity C234 another termination；

Signal after first switch capacitance network integration carries out integral iteration by second switch capacitance network；DC loops 230 have identical DC current gain with loop 220 at a slow speed；The frequency response of DC loops 230 rings less than the frequency of loop 220 at a slow speed Should；Link where first switch capacitance network constitutes the DC loops of system, the mistake of error amplifier 123 in controlling switch power supply Voltage and system line is adjusted to mend the DC components such as electric current.

Specifically, it is narrow pulse signal reverse each other to switch K231 and K232 control signals, by the letter on electric capacity C223 Number signal is transmitted to electric capacity C233 and C234 by switching K231 and K232 Cycle by Cycle, system switching cycle transmits once, After multiple system switching cycles, signal on electric capacity C234 is close to the signal on electric capacity C223；Signal and electricity on electric capacity C234 Signal low-frequency gain is identical on appearance C223, and cut-off frequency is lower, forms the DC loops of switching power control system；Signal 235 is controlled The offset voltage of error amplifier 123, the output line of Switching Power Supply processed mend the DC components such as voltage.

Fig. 3 is the multistage loop response schematic diagram of the utility model embodiment.Signal 301,302 and shown in Fig. 3 303 correspond to the frequency-response characteristic curve of fast loop, at a slow speed loop and DC loops respectively；They have the increasing of identical low frequency Benefit, the cut-off frequency highest of fast loop frequency curve 301, at a slow speed the cut-off frequency of loop frequency curve 302 take second place, DC loops The cut-off frequency of frequency curve 303 is minimum.

As a kind of more excellent embodiment of the present utility model, as shown in figure 4, can be in first switch capacitance network two The both ends difference parallel connection that K232 is switched in end and second switch capacitance network accelerates branch road；It is described to accelerate branch road to include in parallel two The opposite diode of individual polar orientation, such as the diode D401 and D402 in Fig. 4, diode D403 and D404；This measure can enter One step improves the dynamic response of system loop；When accelerating branch road to meet condition, first switch capacitance network and second in loop The loop response of switched capacitor network is identical with fast loop response cut-off frequency, and now loop and DC loops convert respectively at a slow speed Into fast loop；When accelerating branch road to be unsatisfactory for condition, first switch capacitance network cut-off frequency is lower than fast loop, and second opens Powered-down content network cut-off frequency is minimum.

Specifically, signal 411 and 412 represents the signal node of loop integrating capacitor at a slow speed in Fig. 4, between two signals Parallel connection two back-to-back diode D401 and D402；When the voltage difference between loop node 411 and 412 at a slow speed exceedes diode During pressure drop, node signal 411 starts to follow with 412, and keeps a diode voltage pressure drop；When the He of loop node 411 at a slow speed When voltage difference between 412 is less than diode drop, node signal 411 automatically exits from 412 following feature, frequency loop Response accelerator automatically exits from.Equally, two in parallel between signal 421 and 422 in Fig. 4 back-to-back diode D403 and D404, as the acceleration branch road of DC loops, improve frequency response.

Peak point current comparator 130 is by comparing power pipe end primary sampling resistor Rcs pressure drop and peak current threshold Voltage, low and high level signal is exported to control power switch pipe N1 shut-off.Drive circuit 131 is converted to PWM weak signals by force Signal, driving power switching tube N1.

Claims

A kind of 1. multistage loop control circuit of primary side feedback Switching Power Supply, it is characterised in that including：Sampling and keep module (121), Base modules (122), error amplifier (123), loop control unit (124), cable voltage-drop compensation module (125), current source (126), peak point current comparator (130), drive circuit (131), latch (132)；

The input of sampling and keep module (121) is used for the feedback signal of sampled representation transformer-secondary voltage and holding；

The inverting input of the output termination error amplifier (123) of sampling and keep module (121), error amplifier (123) The output end of homophase input termination base modules (122), the output termination loop control unit (124) of error amplifier (123) Input；

Loop control unit (124) includes fast loop (210), at a slow speed loop (220) and DC loops (230)；Fast loop (210) change of the switching frequency of controlling switch power supply, the S inputs of the output termination latch (132) of fast loop (210) End；The output termination peak value of the change of the peak current threshold of loop (220) controlling switch power supply at a slow speed, at a slow speed loop (220) The inverting input of current comparator (130)；DC loops (230) control error amplifier (123) imbalance, Switching Power Supply it is defeated The change of voltage, the output end wiring cable voltage-drop compensation module (125) of DC loops (230), cable voltage-drop compensation module are mended in outlet (125) current source (126) is connect, the output of current source (126) connects the input of sampling and keep module (121)；

The R input of latch (132) connects the output end of peak point current comparator (130), and the Q output of latch (132) connects The input of drive circuit (131), the drive end of the output end of drive circuit (131) as multistage loop control circuit；Peak value Primary current sampling feedback end of the in-phase input end of current comparator (130) as multistage loop control circuit.
2. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 1, it is characterised in that

Fast loop (210) includes PWM comparators (213), sawtooth signal generator (212)；The same phase of PWM comparators (213) The output end of input termination sawtooth signal generator (212), the output end of anti-phase input termination error amplifier (123), PWM ratios Compared with the S inputs of the output termination latch (132) of device (213)；

Loop (220) includes amplitude limit follower (221), first switch capacitance network, peak point current base modules (225) at a slow speed； The output end of the input termination error amplifier (123) of amplitude limit follower (221), output terminate the defeated of first switch capacitance network Enter end, the input of the output termination peak point current base modules (225) of first switch capacitance network, peak point current base modules (225) output connects the inverting input of peak point current comparator (130)；Output signal (211) warp of error amplifier (123) Amplitude limit follower (221) is crossed, the error signal after being limited is input to first switch capacitance network and carries out integral iteration；

DC loops (230) include second switch capacitance network, and the signal after first switch capacitance network integrates passes through second switch Capacitance network carries out integral iteration.
3. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 2, it is characterised in that

First switch capacitance network includes electric capacity C222, C223 and electric-controlled switch K224；An electric capacity C222 termination amplitude limit follows The output end of device (221) and one end that electric capacity C223 is met by electric-controlled switch K224, electric capacity C223 one end is as first switch The output end of capacitance network；Electric capacity C222 and the C223 other end connect primary ground.
4. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 3, it is characterised in that

First switch capacitance network carries out an integral iteration in each PWM switch periods.
5. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 2, it is characterised in that

Second switch capacitance network includes electric-controlled switch K231 and K232, electric capacity C233, C234；An electric-controlled switch K231 termination The output end of first switch capacitance network, another termination electric-controlled switch K232 one end and electric capacity C233 one end, electric capacity C233 The primary ground of another termination；Electric-controlled switch K232 another termination capacitor C234 one end and connection cables voltage-drop compensation module 125；The primary ground of electric capacity C234 another termination.
6. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 5, it is characterised in that

It is narrow pulse signal reverse each other to switch K231 and K232 control signals, the letter after first switch capacitance network is integrated Number signal is transmitted to electric capacity C233 and C234 by switching K231 and K232 Cycle by Cycle, PWM switch periods are transmitted once.
7. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 2, it is characterised in that

Loop (220) has identical DC current gain with fast loop (210) at a slow speed；At a slow speed loop (220)-three dB bandwidth is small In fast loop (210), the frequency response of loop (220) at a slow speed is less than the frequency response of fast loop (210)；

DC loops (230) have identical DC current gain with loop (220) at a slow speed；DC loops (230)-three dB bandwidth be less than it is slow Fast loop (220), the frequency response of DC loops (230) are less than the frequency response of loop (220) at a slow speed.
8. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 2, it is characterised in that

In first switch capacitance network both ends acceleration branch road in parallel；Two polar orientations for accelerating branch road to include parallel connection are opposite Diode.
9. the multistage loop control circuit of primary side feedback Switching Power Supply as claimed in claim 5, it is characterised in that

K232 both ends acceleration branch road in parallel is switched in second switch capacitance network；It is described to accelerate branch road to include in parallel two The opposite diode of polar orientation.