CN116436313A

CN116436313A - Power supply system, constant voltage and constant current control circuit, chip and control method

Info

Publication number: CN116436313A
Application number: CN202210001816.0A
Authority: CN
Inventors: 李亮; 盛欢; 吴泉清
Original assignee: CRM ICBG Wuxi Co Ltd
Current assignee: CRM ICBG Wuxi Co Ltd
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2023-07-14

Abstract

The invention provides a power supply system, a constant voltage and constant current control circuit, a chip and a control method, comprising the following steps: the voltage-controlled timing module generates corresponding timing time based on a feedback signal of the output voltage, detects a zero crossing point based on a zero crossing detection signal, and generates a setting signal when the timing time is over and the zero crossing point arrives; the output current calculation module outputs a peak value maintaining signal of a source electrode of the power switching tube when the power switching tube is turned off, and outputs and connects with a reference ground when the power switching tube is turned on; the transconductance amplification module is connected with the output end of the output current calculation module and a first reference signal; the comparison module is connected with the output end of the transconductance amplification module and the drain electrode of the power switch tube; the triggering module outputs a control signal of the power switching tube; the driving module drives the power switch tube based on the control signal. The invention adopts a frequency conversion architecture, adopts the turn-off time of the power switch tube to replace the inductance demagnetizing time for calculation, changes the voltage-controlled oscillation module into the voltage-controlled timing module, has simple circuit structure and low chip cost.

Description

Power supply system, constant voltage and constant current control circuit, chip and control method

Technical Field

The present invention relates to the field of integrated circuit design, and in particular, to a power supply system, a constant voltage and constant current control circuit, a chip, and a control method.

Background

Along with the current trend of the competition of the low-medium power AC-DC chip cost performance, the traditional fixed frequency architecture is optimized to the greatest extent, the size of a chip circuit is difficult to reduce, and in order to further reduce the cost, a new control architecture is needed to continuously reduce the circuit, so that the chip cost is optimized.

Therefore, how to propose a new control architecture to reduce the chip size has become one of the problems to be solved by those skilled in the art.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a power supply system, a constant voltage and constant current control circuit, a chip and a control method for solving the problem of high cost of a low-power AC-DC chip in the prior art.

To achieve the above and other related objects, the present invention provides a constant voltage and constant current control circuit, including at least:

the device comprises a voltage-controlled timing module, a triggering module, an output current calculation module, a transconductance amplification module, a comparison module, a driving module and a power switch tube;

the voltage-controlled timing module receives an output signal of the trigger module, a feedback signal of the output voltage of the switching power supply conversion circuit and a zero-crossing detection signal, generates corresponding timing time based on the feedback signal of the output voltage, detects a zero crossing point based on the zero-crossing detection signal, and generates a setting signal of the trigger module when the timing time is over and the zero crossing point arrives;

the output current calculation module is connected with the output end of the trigger module and the source electrode of the power switch tube to obtain an output current calculation value; when the power switch tube is turned off, outputting a peak hold signal of the source electrode of the power switch tube; when the power switch tube is conducted, the output is connected with the reference ground;

the inverting input end of the transconductance amplification module is connected with the output end of the output current calculation module, the non-inverting input end of the transconductance amplification module is connected with a first reference signal, and the output end of the transconductance amplification module is grounded through a first capacitor;

the non-inverting input end of the comparison module is connected with the output end of the transconductance amplification module, the inverting input end of the comparison module is connected with the source electrode of the power switch tube, and a comparison result is output;

the setting end of the trigger module is connected with the output end of the voltage-controlled timing module, the resetting end of the trigger module is connected with the output end of the comparison module, and the output end outputs a control signal of the power switch tube;

the input end of the driving module is connected with the output end of the triggering module, the output end of the driving module is connected with the grid electrode of the power switch tube, and the power switch tube is driven based on the control signal.

Optionally, the voltage-controlled timing module includes an operational amplifier, a first resistor, a first NMOS transistor, a second NMOS transistor, a first PMOS transistor, a second capacitor, a first comparator, a second comparator, and a logic unit;

one end of the first resistor is grounded, and the other end of the first resistor is connected with the source electrode of the first NMOS tube;

the non-inverting input end of the operational amplifier is connected with the feedback signal of the output voltage, the inverting input end of the operational amplifier is connected with the source electrode of the first NMOS tube, and the output end of the operational amplifier is connected with the grid electrode of the first NMOS tube;

the input end of the current mirror is connected with the drain electrode of the first NMOS tube, and the output end of the current mirror is connected with the source electrode of the first PMOS tube;

the gates of the first PMOS tube and the second NMOS tube are connected with the output signal of the trigger module, the drains of the first PMOS tube and the second NMOS tube are grounded through the second capacitor, and the source of the second NMOS tube is grounded;

the non-inverting input end of the first comparator is connected with the upper polar plate of the second capacitor, and the inverting input end receives a first threshold voltage;

the non-inverting input end of the second comparator receives a second threshold voltage, and the inverting input end of the second comparator is connected with the zero-crossing detection signal;

the logic unit is connected to the output ends of the first comparator and the second comparator, and generates the setting signal based on the backward turning points in the first comparator and the second comparator.

Optionally, the output current calculation module includes a sample-and-hold unit, a first transmission gate and a second transmission gate; the input end of the sampling and holding unit is connected with the source electrode of the power switch tube, the control end of the sampling and holding unit is connected with the output end of the trigger module, and the peak voltage of the source electrode of the power switch tube is sampled and held; the input end of the first transmission gate is connected with the output end of the sampling and holding unit, and the output end is used as the output end of the output current calculation module; the input end of the second transmission gate is grounded, and the output end of the second transmission gate is connected with the output end of the first transmission gate; the first transmission gate is turned on when the power switch tube is turned off, and the second transmission gate is turned on when the power switch tube is turned on.

Optionally, the connection relation of the output current calculation module is replaced by: the output current calculation module is connected with the output ends of the trigger module and the transconductance amplification module, and outputs an output signal of the transconductance amplification module when the power switch tube is turned off; when the power switch tube is conducted, the output is connected with the reference ground.

More optionally, the output current calculation module includes a first transmission gate and a second transmission gate; the input end of the first transmission gate is connected with the output end of the transconductance amplifying module, and the output end is used as the output end of the output current calculating module; the input end of the second transmission gate is grounded, and the output end of the second transmission gate is connected with the output end of the first transmission gate; the first transmission gate is turned on when the power switch tube is turned off, and the second transmission gate is turned on when the power switch tube is turned on.

More optionally, the constant voltage and constant current control circuit further comprises a sample hold module and an operational amplifier module; the sampling and holding module receives the zero-crossing detection signal and samples and holds the zero-crossing detection signal; and the inverting input end of the operational amplification module receives the output end of the sampling and holding module, the non-inverting input end receives a second reference signal, and the output end replaces the feedback signal of the output voltage to be connected with the input end of the voltage-controlled timing module.

To achieve the above and other related objects, the present invention provides a constant voltage and constant current control chip, which at least includes:

the constant voltage constant current control circuit comprises a feedback pin, a zero crossing detection pin, a sampling pin, a switch pin, a power supply pin and the constant voltage constant current control circuit;

the feedback pin is connected with the feedback signal of the output voltage, the zero-crossing detection pin is connected with the zero-crossing detection signal, the sampling pin is connected with the source electrode of the power switch tube, the switch pin is connected with the drain electrode of the power switch tube, and the power supply pin is connected with the switch pin through a power tube.

zero crossing detection pin, sampling pin, switch pin, power supply pin and constant voltage and constant current control circuit;

the zero-crossing detection pin is connected with the zero-crossing detection signal, the sampling pin is connected with the source electrode of the power switch tube, the switch pin is connected with the drain electrode of the power switch tube, and the power supply pin is connected with the switch pin through a power tube.

To achieve the above and other related objects, the present invention provides a power supply system including at least:

a switching power supply conversion circuit and the constant voltage and constant current control circuit;

the drain electrode of the power switch tube receives the primary winding of the switching power supply conversion circuit, and the source electrode is grounded through a sampling resistor;

and the voltage-controlled timing module acquires a feedback signal of the output voltage from the secondary side of the switching power supply conversion circuit, and acquires the zero-crossing detection signal from an auxiliary winding of the switching power supply conversion circuit.

the voltage-controlled timing module acquires the zero-crossing detection signal from an auxiliary winding of the switching power supply conversion circuit.

To achieve the above and other related objects, the present invention provides a constant voltage and constant current control method, which is implemented based on the above constant voltage and constant current control circuit, and the constant voltage and constant current control method at least includes:

the turn-off time of the power switch tube is adjusted according to the feedback signal of the output voltage under the constant voltage mode based on the constant voltage loop, so as to realize constant voltage control;

and adjusting the opening time based on the constant current loop according to the difference value between the calculated value of the output current and the first reference signal in a constant current mode so as to realize constant current control.

Optionally, the constant voltage and constant current control method satisfies:

wherein Iref is the first reference signal, vcspk is the peak hold signal of the power switch tube source, toff is the turn-off time of the power switch tube, and T is the switching period of the power switch tube.

As described above, the power supply system, the constant voltage and constant current control circuit, the chip and the control method of the invention have the following beneficial effects:

1. the power supply system, the constant voltage and constant current control circuit, the chip and the control method adopt a frequency conversion framework, and compared with the frequency conversion framework, the frequency conversion framework does not need a voltage ring comparator and a logic small module, and the circuit structure is simple, so that the cost of the chip is reduced.

2. The output current calculation module of the power supply system, the constant voltage and constant current control circuit, the chip and the control method adopts the turn-off time of the power switch tube to replace the inductance demagnetizing time for calculation, so that the sampling circuit of the inductance demagnetizing time is saved, the circuit structure is simple, and the cost of the chip is reduced.

3. The power supply system, the constant voltage and constant current control circuit, the chip and the control method change the voltage-controlled oscillation module into the voltage-controlled timing module, the loop is easy to control, the circuit structure is simple, and the cost of the chip is reduced.

Drawings

FIG. 1 shows a schematic diagram of a control chip structure of an SSR architecture.

Fig. 2 is a schematic diagram of a structure of the constant voltage and constant current control circuit and the chip of the present invention.

Fig. 3 is a schematic diagram of a voltage-controlled timing module according to the present invention.

Fig. 4 is a schematic diagram of an output current calculating module according to the present invention.

Fig. 5 shows another schematic diagram of the constant voltage and constant current control circuit and the chip of the present invention.

Fig. 6 is a schematic diagram of another structure of the output current calculating module according to the present invention.

Fig. 7 shows a schematic diagram of still another structure of the constant voltage and constant current control circuit and the chip of the present invention.

Fig. 8 is a schematic diagram of a power supply system according to the present invention.

Fig. 9 is a schematic diagram of another structure of the power supply system of the present invention.

Description of element reference numerals

1. Control chip

11. Voltage controlled oscillator

12. Constant voltage comparator

13. Output current estimation module

14. Transconductance amplifier

15. Constant current comparator

16. Logic module

17 RS trigger

18. Driving module

2. Constant voltage and constant current control circuit

21. Voltage-controlled timing module

211. Operational amplifier

212. Current mirror

213. First comparator

214. Second comparator

215. Logic unit

22. Trigger module

23. Output current calculation module

231. Sample-and-hold unit

232. Inverter with a high-speed circuit

24. Transconductance amplifying module

25. Comparison module

26. Driving module

27. Sample-and-hold module

28. Operational amplifier module

3. Rectifier device

4. Voltage stabilizer

5. Optical coupler

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.

Please refer to fig. 1-9. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

The medium and small power AC-DC power supply generally adopts flyback topology, the small power adopts PSR architecture, and the small power adopts SSR (secondary side feedback) architecture slightly larger. As shown in fig. 1, in a control chip 1 of an SSR architecture, a constant voltage loop obtains a feedback signal FB from a secondary side, and forms a constant voltage control signal based on the feedback signal FB; the constant current loop estimates the output current Io through the demagnetization time signal tdis detected by the zero crossing detection pin ZCD and the peak sampling signal Vcspk sampled and held at the turn-off time in the output current estimation module 13, and then the output current Io and the voltage reference Iref representing the given output current are sent to the transconductance amplifier 14 together, and after closed loop adjustment, a control signal of the next beat of peak sampling signal Vcspk is formed. The constant voltage and constant current loops act simultaneously, the logic module 16 judges who the two comparators (the constant voltage comparator 12 and the constant current comparator 15) turn signals to select as Reset signals of the RS trigger 17, and finally the driving module 18 outputs driving signals. The Set signal of the RS flip-flop 17 is generated by a voltage controlled oscillator 11, the frequency of which voltage controlled oscillator 11 is controlled by a feedback signal FB, the higher the feedback signal FB the higher the frequency.

The constant voltage loop and the constant current loop respectively adopt closed loops to calculate the sampling value Vcspk of the primary side current, and the small value of the constant voltage loop and the constant current loop is adopted to determine the final sampling value Vcspk of the primary side current. If the frequency conversion architecture is adopted, the circuit design can be simplified, so that the size of the whole chip is reduced, and the cost of the chip is reduced; however, the frequency conversion architecture for adjusting the value of the Vcspk by relatively fixing toff time is adopted, and similar to the fixed frequency method, the voltage-controlled oscillator (VCO) is simply changed into a voltage-controlled timer (VCT), the constant voltage control loop is still controlled by a method of determining the sampling value Vcspk of the primary side current by who is small, and the whole logic is not simplified.

Based on the above reasons, the present invention provides a new frequency conversion architecture, so as to simplify the circuit structure to the greatest extent and reduce the chip cost, which will be described in detail below.

Example 1

As shown in fig. 2, the present embodiment provides a constant voltage and constant current control circuit 2, the constant voltage and constant current control circuit 2 including:

the circuit comprises a voltage-controlled timing module 21, a triggering module 22, an output current calculation module 23, a transconductance amplification module 24, a comparison module 25, a driving module 26 and a power switch tube Q1.

As shown in fig. 2, the voltage-controlled timing module 21 receives the output signal of the trigger module 22, the feedback signal FB of the output voltage of the switching power supply conversion circuit, and the zero-crossing detection signal ZCD, generates a corresponding timing time based on the feedback signal FB of the output voltage, detects a zero-crossing point based on the zero-crossing detection signal ZCD, and generates a set signal of the trigger module 22 when the timing time is over and the zero-crossing point arrives.

Specifically, as shown in fig. 3, in the present embodiment, the voltage-controlled timing module 21 includes an operational amplifier 211, a first resistor R1, a first NMOS transistor MN1, a current mirror 212, a second NMOS transistor MN2, a first PMOS transistor MP1, a second capacitor C2, a first comparator 213, a second comparator 214, and a logic unit 215. One end of the first resistor R1 is grounded, and the other end of the first resistor R1 is connected with the source electrode of the first NMOS tube MN 1. The non-inverting input end of the operational amplifier 211 is connected to the feedback signal FB of the output voltage, the inverting input end is connected to the source electrode of the first NMOS transistor MN1, and the output end is connected to the gate electrode of the first NMOS transistor MN 1. The input end of the current mirror 212 is connected with the drain electrode of the first NMOS tube MN1, and the output end is connected with the source electrode of the first PMOS tube MP 1; as an example, the current mirror 212 is composed of two PMOS transistors. The gates of the first PMOS transistor MP1 and the second NMOS transistor MN2 are connected to the output signal Q of the trigger module 22, the drains of the first PMOS transistor MP1 and the second NMOS transistor MN2 are grounded via the second capacitor C2, and the source of the second NMOS transistor MN2 is grounded. The non-inverting input terminal of the first comparator 213 is connected to the upper plate of the second capacitor C2, and the inverting input terminal receives the first threshold voltage Vth1. The non-inverting input terminal of the second comparator 214 receives the second threshold voltage Vth2, and the inverting input terminal is connected to receive the zero-crossing detection signal ZCD. The logic unit 215 is connected to the output ends of the first comparator 213 and the second comparator 214, and generates the set signal S based on a flip point in the first comparator 213 and the second comparator 214.

The feedback signal of the output voltage is related to the output voltage of the switching power supply conversion circuit. As an example, the feedback signal of the output voltage is inversely proportional to the output voltage; in practical use, the relation between the feedback signal of the output voltage and the output voltage may be set according to the need, and the feedback signal of the output voltage may reflect the change of the output voltage, which is not limited by the embodiment.

As shown in fig. 2, the output current calculating module 23 is connected to the output end of the triggering module 22 and the source electrode of the power switch tube Q1 to obtain an output current calculated value; when the power switch tube Q1 is turned off, outputting a peak value holding signal Vcspk of a source electrode of the power switch tube Q1; when the power switch tube Q1 is conducted, the output is connected with the reference ground.

Specifically, as shown in fig. 4, in the present embodiment, the output current calculating module 23 includes a sample-and-hold unit 231, a first transmission gate SW1, and a second transmission gate SW2. The input end of the sample-hold unit 231 is connected to the source electrode of the power switch tube Q1, the control end is connected to the output end Q of the trigger module 22, and the peak voltage Vcspk of the source electrode of the power switch tube Q1 is sampled and held. An input terminal of the first transmission gate SW1 is connected to an output terminal of the sample-and-hold unit 231, and an output terminal is used as an output terminal of the output current calculation module 23. The input end of the second transmission gate SW2 is grounded, and the output end of the second transmission gate SW1 is connected to the output end. The output current calculating module 23 further includes an inverter 232 for providing an inverse of the output signal of the triggering module 22, wherein the output signal of the triggering module 22 and the inverse thereof are used as control signals of the first transmission gate SW1 and the second transmission gate SW2; the sample hold unit 231 operates and the first transmission gate SW1 is turned on when the power switching transistor Q1 is turned off, and the second transmission gate SW2 is turned on when the power switching transistor Q1 is turned on.

As shown in fig. 2, the inverting input terminal of the transconductance amplifying module 24 is connected to the output terminal of the output current calculating module 23, the non-inverting input terminal is connected to the first reference signal Iref, and the output terminal is grounded via the first capacitor C1.

As shown in fig. 2, the non-inverting input end of the comparing module 25 is connected to the output end of the transconductance amplifying module 24, and the inverting input end is connected to the source electrode of the power switching tube Q1, so as to output the comparison result.

As shown in fig. 2, the set end of the trigger module 22 is connected to the output end of the voltage-controlled timing module 21, the reset end is connected to the output end of the comparison module 25, and the output end outputs the control signal of the power switch Q1.

Specifically, in this embodiment, the triggering module 22 is implemented by using an RS trigger, and in actual use, a corresponding module with a triggering function may be selected according to needs, which is not limited to this embodiment.

As shown in fig. 2, the input end of the driving module 26 is connected to the output end of the triggering module 22, the output end is connected to the gate of the power switch Q1, and the power switch Q1 is driven based on the control signal.

As shown in fig. 2, in the constant voltage and constant current control circuit 2 of the present invention, the voltage control timing module 21 and the trigger module 22 form a part of a constant voltage loop, the output current calculation module 23, the transconductance amplification module 24, the comparison module 25 and the trigger module 22 form a part of a constant current loop, the turn-off time of the power switch tube is adjusted according to the feedback signal FB of the output voltage in the constant voltage mode based on the constant voltage loop, and the turn-on time is adjusted according to the difference value between the output current calculation value and the first reference signal in the constant current mode based on the constant current loop, so as to separate the constant voltage control from the constant current control without interfering with each other, and realize the bidirectional smooth switching of the system between the constant voltage mode and the constant current mode during the load variation, so that the overall logic is simplified.

The embodiment also provides a constant voltage and constant current control method, which is realized based on the constant voltage and constant current control circuit 2, and comprises the following steps:

the turn-off time of the power switch tube is adjusted according to the feedback signal of the output voltage under the constant voltage mode based on the constant voltage loop, so as to realize constant voltage control; based on the constant current loop, adjusting the opening time according to the difference value between the calculated value of the output current and the first reference signal in a constant current mode so as to realize constant current control; the constant voltage and constant current control method meets the following conditions:

Specifically, as shown in fig. 3, the voltage-controlled timing module 21 converts the voltage of the feedback signal FB of the output voltage into a current VFB/R1, copies the current to the paths of the first PMOS MP1 and the second NMOS MN2 through the 1:1 current mirror 212, the output signal Q of the trigger module 22 is used as a switch control signal, and in the off period toff of the power switch Q1, the first PMOS MP1 is turned on, and the second capacitor C2 is in a charging state; during the on period ton of the power switch Q1, the second NMOS transistor MN2 is turned on, and the second capacitor C2 is reset by discharging. Meanwhile, the first comparator 213 is turned over (high level) after the voltage on the second capacitor C2 is charged to the first threshold voltage Vth1 during the off period toff of the power switching transistor Q1. When the zero-crossing detection signal ZCD is smaller than the second threshold voltage Vth2, the second comparator 214 toggles (is high level). The logic unit 215 selects the signal after comparing the two inversion points of the first comparator 213 and the second comparator 214 as the set signal of the subsequent trigger module 22, so as to ensure that the system does not operate in CCM (continuous mode). In the constant voltage control section, the turn-off time toff of the power switch tube Q1 is calculated by the formula

Determining; in the constant current control section, the feedback signal FB due to the output voltage is pushed to the mostThe calculated off time toff time of the power switch tube Q1 is smaller than the actual inductance demagnetization time tdis due to the large value, and the system enters a BCM mode (critical mode), so that in a constant current control section, the final actual off time toff of the power switch tube Q1 is equal to the inductance demagnetization time tdis, and the effect of constant current is achieved.

Specifically, as shown in fig. 4, in the original fixed frequency architecture, the magnitude of the output current is estimated by time interception of the peak hold of the CS signal at the switch off moment and the inductor demagnetization time tdis signal; the estimated output current value is fed into the transconductance amplifier 14 together with Iref to realize closed loop control, i.e. mainly

Is provided. In the frequency conversion architecture of the present invention, since the feedback amount of the constant voltage loop (i.e., the feedback signal FB of the output voltage) cannot control the peak hold signal Vcspk of the source electrode of the power switch Q1, if the peak hold signal Vcspk of the source electrode of the power switch Q1 still is still according to the original calculation mode, the peak hold signal Vcspk of the source electrode of the power switch Q1 will become larger because the inductance demagnetization time tdis is too small, which will cause that the frequency of the constant voltage segment cannot be reduced in the light load segment. Thus, change to +.>

I.e. < ->

As the load of the constant voltage section becomes lighter, the turn-off time toff of the power switch tube Q1 is lengthened, and the peak hold signal Vcspk of the source of the power switch tube Q1 becomes smaller gradually, and finally approaches to the first reference signal Iref. In the constant current stage, since the inductance demagnetizing time tdis is approximately equal to the turn-off time toff of the power switch Q1 in the voltage-controlled timing module 21, the turn-off time toff of the power switch Q1 in the above formula is replaced by the inductance demagnetizing time tdis, and the condition of constant current in the constant current stage can still be satisfied>

Example two

As shown in fig. 5 and 6, the present embodiment provides a constant voltage and constant current control circuit, which is different from the first embodiment in that the connection relationship of the output current calculation module 23 is replaced by: the output current calculation module 23 is connected to the output ends of the trigger module 22 and the transconductance amplification module 24, and outputs an output signal of the transconductance amplification module 24 when the power switch tube Q1 is turned off; when the power switch tube Q1 is conducted, the output is connected with the reference ground.

Specifically, the output signal of the transconductance amplifying module 24 is substantially identical to the source signal of the power switch Q1, and in this embodiment, the output signal of the transconductance amplifying module 24 is used to replace the source signal of the power switch Q1, so that logic can be further simplified. As shown in fig. 6, at this time, the output current calculating module 23 includes a first transmission gate SW1 and a second transmission gate SW2; the input end of the first transmission gate SW1 is connected to the output end of the transconductance amplifying module 24, and the output end is used as the output end gmout of the output current calculating module 22; the input end of the second transmission gate SW2 is grounded, and the output end of the second transmission gate SW1 is connected to the output end. The output current calculating module 23 further includes an inverter 232 for providing an inverse of the output signal of the triggering module 22, wherein the output signal of the triggering module 22 and the inverse thereof are used as control signals of the first transmission gate SW1 and the second transmission gate SW2; the first transmission gate SW1 is turned on when the power switching tube Q1 is turned off, and the second transmission gate SW2 is turned on when the power switching tube Q1 is turned on.

It should be noted that other devices, connection relationships and operation principles are similar to those of the embodiments, and are not described in detail herein.

Example III

As shown in fig. 7, this embodiment provides a constant voltage and constant current control circuit 2, which is different from the first and second embodiments in that the constant voltage and constant current control circuit further includes a sample-and-hold module 27 and an operational amplifier module 28.

Specifically, the sample-hold module 27 receives the zero-crossing detection signal ZCD, and samples and holds the voltage of the zero-crossing detection signal ZCD before the secondary side current freewheeling of the switching power supply conversion circuit is finished in the off period of the power switch tube Q1. The inverting input end of the operational amplification module 28 is connected to the output end of the sample-and-hold module, the non-inverting input end of the operational amplification module receives the second reference signal Vref, and the output end of the operational amplification module is connected to the input end of the voltage-controlled timing module 21. At this time, the voltage-controlled timing module 21 does not receive the feedback signal FB.

In this embodiment, the sample-hold module 27 and the operational amplifier module 28 are added on the basis of the first embodiment, and the sample-hold module 27 and the operational amplifier module 28 may be added on the basis of the second embodiment; other devices, connection relationships, and operation principles are similar to those of the embodiments and are not described in detail herein.

Example IV

As shown in fig. 2 and 5, the present embodiment provides a constant voltage and constant current control chip, which includes:

a feedback pin FB, a zero-crossing detection pin ZCD, a sampling pin CS, a switch pin SW, a power supply pin VDD, and the constant voltage and constant current control circuit 2 of the first or second embodiment.

Specifically, the feedback pin FB is connected to the feedback signal FB of the output voltage, and is used for introducing an external feedback signal into the constant voltage and constant current control chip. The zero-crossing detection pin ZCD is connected with the zero-crossing detection signal ZCD and is used for introducing an external zero-crossing detection signal into the constant voltage constant current control chip. The sampling pin CS is connected with the source electrode of the power switch tube Q1 and is used for introducing a sampling signal of the source electrode of the power switch tube Q1 into the constant voltage and constant current control chip. The switch pin SW is connected to the drain of the power switch tube Q1, and is used for implementing connection between an external circuit and the drain of the power switch tube Q1. The power supply pin VDD is connected with the switch pin SW through a power tube K; in the initial stage, the power tube K is turned on, and the switch pin SW obtains electric energy from the outside to supply power to the constant voltage and constant current control chip, in this embodiment, the power tube K is a JFET, and in actual use, a corresponding device can be selected according to needs, which is not limited by this embodiment; when the starting voltage of the constant voltage and constant current control chip is reached, the power tube K is turned off, and the power pin VDD obtains electric energy from the outside to supply power for the constant voltage and constant current control chip. As an example, the switch pin SW obtains power from the primary winding, and the power pin VDD obtains power from the auxiliary winding, which is not limited to the present embodiment.

Example five

As shown in fig. 7, this embodiment provides a constant voltage and constant current control chip, which is different from the fourth embodiment in that the constant voltage and constant current control chip does not need a feedback pin FB.

Specifically, the constant voltage and constant current control chip includes a zero crossing detection pin ZCD, a sampling pin CS, a switch pin SW, a power supply pin VDD, and the constant voltage and constant current control circuit 2 of the third embodiment.

It should be noted that, the other structures are the same as those of the fourth embodiment, and are not described in detail herein.

Example six

As shown in fig. 8, the present embodiment provides a power supply system including:

and the switching power supply conversion circuit and the constant voltage and constant current control circuit 2.

Specifically, the constant voltage and constant current control circuit 2 is implemented by adopting the constant voltage and constant current control circuit in the first embodiment or the second embodiment, which is not described herein in detail.

As shown in fig. 8, as an example, the switching power supply conversion circuit is an SSR system of secondary side feedback, and includes: a rectifier 3 converting the alternating current power supply AC in into a bus voltage; the two ends of the rectifier 3 are connected in parallel with a third capacitor C3; one end of the primary winding is connected with the busbar voltage, and the other end of the primary winding is connected with the anode of the first diode D1; the negative electrode of the first diode D1 is connected with the bus voltage through a second resistor R2 and a fifth capacitor which are connected in parallel; one end of the auxiliary winding is connected with the positive electrode of the second diode D2, and the other end of the auxiliary winding is grounded; the cathode of the second diode D2 is grounded through a fourth capacitor C4; the third resistor R3 and the fourth resistor R4 are connected in series and then connected in parallel with the two ends of the auxiliary winding; one end of the secondary winding is connected with the positive electrode of the third diode D3, and the other end of the secondary winding is grounded; the cathode of the third diode D3 is grounded through a sixth capacitor C6; the fifth resistor R5 is connected in parallel with two ends of the sixth capacitor C6 and outputs a direct current power DCout; one end of the sixth resistor R6 is connected to the negative electrode of the third diode D3, and the other end is grounded through the input side of the optocoupler 5 and the voltage stabilizer 4 (TL 431 chip is used as an example); the seventh resistor R7 and the eighth resistor R8 are connected in series and then connected between the cathode of the third diode D3 and the ground; the ninth resistor R9 and the seventh capacitor C7 are connected in series and then connected between the cathode of the voltage regulator 4 and the connection node between the seventh resistor and the eighth resistor R8.

As shown in fig. 8, as an example, the drain (SW pin) of the power switch Q1 is connected to the primary winding of the switching power supply conversion circuit, and the source (CS pin) is grounded via the sampling resistor R10. The feedback signal FB port (FB pin) of the output voltage is connected to the output side of the optocoupler 5, so that the voltage-controlled timing module 21 obtains the feedback signal FB of the output voltage from the secondary side of the switching power supply conversion circuit; the FB pin is also connected to an eighth capacitor C8 having one end grounded. The zero-crossing detection signal ZCD port (ZCD pin) connects the connection node of the third resistor R3 and the fourth resistor R4, so that the voltage-controlled timing module 21 obtains the zero-crossing detection signal ZCD from the auxiliary winding of the switching power supply conversion circuit. As another example, a power supply voltage VDD port (VDD pin) is connected to the negative electrode of the second diode D2 to obtain the power supply voltage VDD from the auxiliary winding of the switching power supply conversion circuit.

It should be noted that, the switching power supply conversion circuit includes, but is not limited to, a flyback topology structure or a forward topology structure, and can implement secondary side feedback, which is not described in detail herein.

Example seven

As shown in fig. 9, the present embodiment provides a power supply system, which is different from the sixth embodiment in that the switching power supply conversion circuit is a PSR system with primary side feedback.

Specifically, the constant voltage and constant current control circuit 2 is implemented by using the constant voltage and constant current control circuit 2 in the third embodiment, which is not described herein in detail.

As shown in fig. 9, the switching power supply conversion circuit does not need a feedback circuit of a secondary side, and in this embodiment, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the seventh capacitor C7, the voltage regulator 4, the optocoupler 5, and the eighth capacitor C8 are eliminated. The constant voltage and constant current control circuit 2 does not need a feedback pin, and realizes two functions of output voltage feedback and zero crossing detection based on the connection node of the third resistor R3 and the fourth resistor R4.

It should be noted that other structures and principles are similar to those of the sixth embodiment, and are not described in detail herein.

In summary, the present invention provides a power supply system, a constant voltage and constant current control circuit, a chip and a control method, including: the device comprises a voltage-controlled timing module, a triggering module, an output current calculation module, a transconductance amplification module, a comparison module, a driving module and a power switch tube; the voltage-controlled timing module receives an output signal of the trigger module, a feedback signal of the output voltage of the switching power supply conversion circuit and a zero-crossing detection signal, generates corresponding timing time based on the feedback signal of the output voltage, detects a zero crossing point based on the zero-crossing detection signal, and generates a setting signal of the trigger module when the timing time is over and the zero crossing point arrives; the output current calculation module is connected with the output end of the trigger module and the source electrode of the power switch tube, and outputs a peak value holding signal of the source electrode of the power switch tube when the power switch tube is turned off; when the power switch tube is conducted, the output is connected with the reference ground; the inverting input end of the transconductance amplification module is connected with the output end of the output current calculation module, the non-inverting input end of the transconductance amplification module is connected with a first reference signal, and the output end of the transconductance amplification module is grounded through a first capacitor; the non-inverting input end of the comparison module is connected with the output end of the transconductance amplification module, the inverting input end of the comparison module is connected with the source electrode of the power switch tube, and a comparison result is output; the setting end of the trigger module is connected with the output end of the voltage-controlled timing module, the resetting end of the trigger module is connected with the output end of the comparison module, and the output end outputs a control signal of the power switch tube; the input end of the driving module is connected with the output end of the triggering module, the output end of the driving module is connected with the grid electrode of the power switch tube, and the power switch tube is driven based on the control signal. The power supply system, the constant voltage and constant current control circuit, the chip and the control method adopt a frequency conversion architecture, and compared with a fixed frequency architecture, a voltage ring comparator and a logic small taking module are not needed; the turn-off time of the power switch tube is adopted to replace the inductance demagnetizing time for calculation, so that the sampling circuit of the inductance demagnetizing time is saved; the voltage-controlled oscillation module is changed into a voltage-controlled timing module, and the loop is easy to control; the circuit structure is simple. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A constant voltage and constant current control circuit, characterized in that the constant voltage and constant current control circuit at least comprises:

the output current calculation module is connected with the output end of the trigger module and the source electrode of the power switch tube to obtain an output current calculation value; when the power switch tube is turned off, outputting a peak hold signal of the source electrode of the power switch tube;

when the power switch tube is conducted, the output is connected with the reference ground;

2. The constant voltage and constant current control circuit according to claim 1, wherein: the voltage-controlled timing module comprises an operational amplifier, a first resistor, a first NMOS tube, a second NMOS tube, a first PMOS tube, a second capacitor, a first comparator, a second comparator and a logic unit;

3. The constant voltage and constant current control circuit according to claim 1, wherein: the output current calculation module comprises a sampling and holding unit, a first transmission gate and a second transmission gate; the input end of the sampling and holding unit is connected with the source electrode of the power switch tube, the control end of the sampling and holding unit is connected with the output end of the trigger module, and the peak voltage of the source electrode of the power switch tube is sampled and held; the input end of the first transmission gate is connected with the output end of the sampling and holding unit, and the output end is used as the output end of the output current calculation module; the input end of the second transmission gate is grounded, and the output end of the second transmission gate is connected with the output end of the first transmission gate; the first transmission gate is turned on when the power switch tube is turned off, and the second transmission gate is turned on when the power switch tube is turned on.

4. The constant voltage and constant current control circuit according to claim 1, wherein: the connection relation of the output current calculation module is replaced by: the output current calculation module is connected with the output ends of the trigger module and the transconductance amplification module, and outputs an output signal of the transconductance amplification module when the power switch tube is turned off; when the power switch tube is conducted, the output is connected with the reference ground.

5. The constant voltage and constant current control circuit according to claim 4, wherein: the output current calculation module comprises a first transmission gate and a second transmission gate; the input end of the first transmission gate is connected with the output end of the transconductance amplifying module, and the output end is used as the output end of the output current calculating module; the input end of the second transmission gate is grounded, and the output end of the second transmission gate is connected with the output end of the first transmission gate; the first transmission gate is turned on when the power switch tube is turned off, and the second transmission gate is turned on when the power switch tube is turned on.

6. The constant voltage and constant current control circuit according to any one of claims 1 to 5, wherein: the constant voltage and constant current control circuit also comprises a sampling hold module and an operational amplifier module; the sampling and holding module receives the zero-crossing detection signal and samples and holds the zero-crossing detection signal; and the inverting input end of the operational amplification module is connected with the output end of the sampling and holding module, the non-inverting input end receives a second reference signal, and the output end replaces the feedback signal of the output voltage to be connected with the input end of the voltage-controlled timing module.

7. The constant voltage and constant current control chip is characterized by at least comprising:

a feedback pin, a zero crossing detection pin, a sampling pin, a switching pin, a power supply pin, and the constant voltage and constant current control circuit according to any one of claims 1 to 5;

8. The constant voltage and constant current control chip is characterized by at least comprising:

a zero-crossing detection pin, a sampling pin, a switching pin, a power supply pin, and the constant voltage and constant current control circuit according to claim 6;

9. A power supply system, the power supply system comprising at least:

a switching power supply conversion circuit and a constant voltage and constant current control circuit according to any one of claims 1 to 5;

the drain electrode of the power switch tube is connected with the primary winding of the switching power supply conversion circuit, and the source electrode is grounded through a sampling resistor;

10. A power supply system, the power supply system comprising at least:

a switching power supply conversion circuit and a constant voltage and constant current control circuit according to claim 6;

11. A constant voltage and constant current control method based on the constant voltage and constant current control circuit according to any one of claims 1-6, characterized in that the constant voltage and constant current control method at least comprises:

12. The constant voltage and constant current control method according to claim 11, wherein: the constant voltage and constant current control method meets the following conditions: