CN109194145B - Drive circuit of push-pull switching power supply and push-pull switching power supply - Google Patents
Drive circuit of push-pull switching power supply and push-pull switching power supply Download PDFInfo
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- CN109194145B CN109194145B CN201811235786.XA CN201811235786A CN109194145B CN 109194145 B CN109194145 B CN 109194145B CN 201811235786 A CN201811235786 A CN 201811235786A CN 109194145 B CN109194145 B CN 109194145B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/337—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration
- H02M3/3376—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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Abstract
The application provides a drive circuit of a push-pull switching power supply and the push-pull switching power supply, wherein the drive circuit provides a drive control signal for a first switching tube in the push-pull switching power supply by utilizing a PWM signal drive unit; the first driving unit obtains a driving control signal for driving the second switching tube according to the voltage on the primary winding of the push-pull transformer, and an inverting unit and a push-pull unit do not need to be arranged for the second switching tube, namely the inverting unit and the push-pull unit are replaced by the first driving unit, so that the hardware cost of the driving circuit is low.
Description
Technical Field
The invention belongs to the technical field of switching power supplies, and particularly relates to a drive circuit of a push-pull switching power supply and the push-pull switching power supply.
Background
The push-pull circuit is an output circuit with two transistor-connected keys of different polarities. The push-pull circuit adopts two power BJT (bipolar junction transistor) tubes or MOSFET (metal-oxide-semiconductor field effect transistor) tubes with the same parameters, and the two power BJT tubes or MOSFET tubes exist in the circuit in a push-pull mode and are respectively responsible for positive and negative half-cycle waveform amplification tasks.
The push-pull switch power supply alternately works by two switch tubes, is equivalent to two switch power supplies outputting power simultaneously, and the output power of the push-pull switch power supply is equal to twice of the output power of a single switch power supply. Therefore, the output power of the push-pull switching power supply is high, and the working efficiency is high.
The open-loop push-pull switching power supply is suitable for being applied to occasions with low cost, constant voltage input and low requirement on output voltage stabilization precision. The common driving mode of the open-loop push-pull switching power supply is a PWM chip driving scheme. The PWM chip driving scheme requires a PWM driving unit and an inverting unit, and when the PWM driving unit is insufficient in driving capability, two driving units are required to be added to drive two switching tubes respectively, that is, each push-pull switching power supply needs to be provided with 1 PWM driving unit, 1 inverting unit, and 2 driving units, resulting in higher hardware cost of the push-pull switching power supply.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a driving circuit of a push-pull switching power supply and a push-pull switching power supply, so as to solve the technical problem of high cost of the driving circuit of the conventional push-pull switching power supply. The specific technical scheme is as follows:
in a first aspect, a driving circuit of a push-pull switching power supply is provided, including: a Pulse Width Modulation (PWM) signal driving unit and a first driving unit;
the output end of the PWM signal driving unit is connected with the control end of a first switching tube in the push-pull switching power supply and is used for generating a PWM driving signal for controlling the switching state of the first switching tube;
the first driving unit is connected between the first end and the second end of the first switch tube in parallel, the output end of the first driving unit is connected with the control end of a second switch tube in the push-pull switch power supply, and the first driving unit controls the switching state of the second switch tube by using the voltage at the two ends of the first switch tube.
Optionally, the first drive unit comprises: the device comprises a first unidirectional conducting device, a voltage stabilizing device and a first resistor;
one end of the first resistor is connected with the first end of the first switching tube, the other end of the first resistor is connected with one end of the voltage stabilizing device, and the other end of the voltage stabilizing device is connected with the second end of the first switching tube;
the common point of the first resistor and the voltage stabilizing device is connected with the control end of the second switching tube;
the negative pole of the first unidirectional conduction device is connected with the first end of the first switch tube, and the positive pole of the first unidirectional conduction device is connected with the common point of the first resistor and the voltage stabilizing device.
Optionally, the voltage regulator device is a voltage regulator tube;
the negative electrode of the voltage-stabilizing tube is connected with the first resistor, and the positive electrode of the voltage-stabilizing tube is connected with the second end of the first switch tube.
Optionally, the voltage stabilizing device is a second resistor;
one end of the second resistor is connected with the first resistor, and the other end of the second resistor is connected with the second end of the first switch tube.
Optionally, the PWM signal driving unit has a current limiting function end, and the driving circuit further includes a current detecting unit;
the current detection unit is connected in series with a branch circuit where the first switch tube or the second switch tube is located, a detection end of the current detection unit is connected with a current limiting function end of the PWM signal driving unit, and the current detection unit is used for sampling current flowing in a primary winding of the push-pull transformer;
and the PWM signal driving unit is also used for outputting a PWM signal with the duty ratio equal to the preset duty ratio after detecting that the voltage of the current limiting function end is higher than the preset voltage threshold value.
Optionally, the current detection unit is a third resistor;
one end of the third resistor is connected with the second end of the first switching tube and the current-limiting function end of the PWM signal driving unit, and the other end of the third resistor is connected with the negative electrode of the input power supply.
Optionally, the PWM signal driving unit includes a first PWM signal generating unit and a second driving unit;
the output end of the first PWM signal generating unit is connected with the input end of the second driving unit;
the output end of the second driving unit is connected with the control end of the first switch tube, and the second driving unit is used for amplifying the PWM signal generated by the first PWM signal generating unit and then driving the first switch tube to be switched on or switched off.
Optionally, the second driving unit comprises a third switching tube and a fourth switching tube with opposite polarities;
the first end of the third switching tube is connected with the anode of the input power supply, the second end of the third switching tube is connected with the control end of the first switching tube after being connected with the second end of the fourth switching tube, the first end of the fourth switching tube is connected with the cathode of the input power supply, and the control end of the third switching tube is connected with the control end of the fourth switching tube and is connected with the output end of the first PWM signal generating unit.
Optionally, the PWM signal driving unit includes a second PWM signal generating unit;
the output end of the second PWM signal generating unit is connected with the control end of the second switch tube, and the second PWM signal generating unit is used for generating a PWM signal for driving the second switch tube to be switched on or switched off.
In a second aspect, the present application further provides a push-pull switching power supply, including a first switching tube, a second switching tube, a push-pull transformer, an output unit, and a driving circuit of the push-pull switching power supply according to any one of possible implementation manners of the first aspect;
the first end of the first switching tube is connected with the non-homonymous end of the second primary winding of the push-pull transformer, the second end of the first switching tube is connected with the negative electrode of the input power supply, and the control end of the first switching tube is connected with the output end of the PWM signal driving unit in the driving circuit;
the first end of the second switching tube is connected with the dotted end of the first primary winding of the push-pull transformer, the second end of the second switching tube is connected with the negative electrode of the input power supply, and the control end of the second switching tube is connected with the output end of the first driving unit in the driving circuit;
the common end of the first primary winding and the second primary winding is connected with the anode of the input power supply;
the dotted terminal of the first secondary winding of the push-pull transformer is connected with the anode of a first one-way conduction device, and the cathode of the first one-way conduction device is connected with the anode of the output unit;
the non-dotted terminal of a second secondary winding of the push-pull transformer is connected with the anode of a second one-way conduction device, and the cathode of the second one-way conduction device is connected with the anode of the output unit;
and the common end of the first secondary winding and the second secondary winding is connected with the negative electrode of the output unit.
In the driving circuit of the push-pull switching power supply provided by the embodiment, the PWM signal driving unit is used to provide a driving control signal for the first switching tube in the push-pull switching power supply; the first driving unit is used for obtaining a driving control signal for driving the second switching tube according to the voltage on the primary winding of the push-pull transformer, an inverting unit and a push-pull unit (the push-pull unit plays an amplifying role) do not need to be arranged for the second switching tube, namely the inverting unit and the push-pull unit are replaced by the first driving unit, and therefore the hardware cost of the driving circuit is low.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a push-pull switching power supply provided in an embodiment of the present application;
fig. 2 is a schematic circuit diagram of another push-pull switching power supply provided in an embodiment of the present application;
fig. 3 is a schematic circuit diagram of another push-pull switching power supply provided in an embodiment of the present application;
fig. 4 is a schematic circuit diagram of another push-pull switching power supply provided in an embodiment of the present application;
fig. 5 is a schematic circuit diagram of another push-pull switching power supply provided in an embodiment of the present application;
fig. 6 is a schematic circuit diagram of another push-pull switching power supply provided in an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a schematic diagram of a push-pull switching power supply according to an embodiment of the present application is shown,
as shown in fig. 1, the push-pull switching power supply includes: the drive circuit constituted by the PWM signal drive unit 1 and the first drive unit 2, and Q1, Q2, the push-pull transformer T, the diode D1, the diode D2, the inductor Lo, and the capacitor Co together constitute a push-pull switching power supply. The driving circuit is used for driving a first switch tube Q1 and a second switch tube Q2 in the push-pull switch power supply.
The power supply end of the PWM signal driving unit 1 is connected to the positive electrode of the input power supply, and the output end of the PWM signal driving unit 1 is connected to the control end of the first switching tube Q1.
The PWM signal driving unit 1 is used to generate a PWM driving signal for controlling the Q1 to be turned on or off. The PWM signal driving unit may be composed of a PWM generating chip, and the frequency and duty ratio of the generated PWM signal may be set according to actual requirements.
One end of the first driving unit 2 is connected to the first end of the Q1, the other end of the first driving unit 2 is connected to the second end of the Q1, and the output end of the first driving unit 2 is connected to the control end of the Q2.
The first driving unit 2 is used for driving the Q2 to be switched on or off by using the voltage on the primary winding of the push-pull transformer T.
The first end of the Q1 is connected with the non-dotted terminal of the second primary winding of the push-pull transformer T, and the second end of the Q1 is connected with the negative pole of the input power supply. The first end of the Q2 is connected with the same-name end of the first primary winding of the T, and the second end of the Q2 is connected with the negative pole of the input power supply. And the common end of the first primary winding and the second primary winding of the T is connected with the positive electrode of the input power supply.
The dotted terminal of the first secondary winding of T is connected with one end of Lo through D1, the other end of Lo is connected with one end of an output capacitor Co, the other end of Co is connected with the common terminal of the first secondary winding and the second secondary winding, and the two ends of Co are the output ends of the output unit. The non-homonymous terminal of the second secondary winding of T is connected with the anode of D2, and the cathode of D2 is connected with the common terminal of D1 and Lo.
Wherein, D1 and D2 are used for rectification, and Lo and Co form an output unit. After a power supply is powered on, the PWM signal driving unit 1 sends out a PWM wave with fixed frequency and fixed duty ratio, and when the PWM wave is a high-level signal, Q1 is conducted; after Q1 is turned on, the voltage at point A is pulled low, and V isABThe first driving unit 2 outputs low level, Q2 is turned off, and the push-pull transformer T is turned onThe load is powered by the D1.
When the PWM wave is a low level signal, Q1 is turned off; the voltage at point A after Q1 is turned off is close to the voltage Vin of the input power supply, and V is at this timeABAt high, the first driving unit 2 outputs high, Q2 is turned on, and T supplies energy to the load through D2. And Q1 and Q2 are alternately conducted, so that the output voltage of the push-pull switching power supply is kept constant. In this case, the driving signal of Q2 is converted by the voltage on the primary winding of the push-pull transformer T, and therefore, it is not necessary to provide an inverting unit and a push-pull unit for Q2 to realize driving control of Q2.
In the driving circuit of the push-pull switching power supply provided by the embodiment, the PWM signal driving unit is used to provide a driving control signal for the first switching tube in the push-pull switching power supply; the first driving unit obtains a driving control signal for driving the second switching tube according to the voltage on the primary winding of the push-pull transformer, and an inverting unit and a push-pull unit do not need to be arranged for the second switching tube, namely the inverting unit and the push-pull unit are replaced by the first driving unit, so that the hardware cost of the driving circuit is low.
Referring to fig. 2, a schematic circuit diagram of another push-pull switching power supply according to an embodiment of the present disclosure is shown, in which a PWM signal driving unit 1 includes a first PWM signal generating unit 11 and a second PWM signal generating unit 12. The first driving unit 2 may include a first unidirectional conducting device, a voltage stabilizing device, and a first resistor.
In this embodiment, the first PWM signal generating unit 11 is implemented by using a 555 timer, and the driving capability of the PWM signal generated by the 555 timer is insufficient, so that the second driving unit 12 needs to be arranged to amplify the PWM signal, and the second driving unit 12 can be implemented by using a push-pull unit.
The VCC pin of the 555 timer is connected with the anode of the input power supply, the OUT pin is used as the output end and connected with the input end of the push-pull unit, and the output end of the push-pull unit is connected with the control end of the Q1.
As shown in fig. 2, the push-pull unit includes a third switching transistor Q3 and a fourth switching transistor Q4, wherein the polarities of Q3 and Q4 are opposite, for example, Q3 is an NPN transistor, and Q4 is a PNP transistor.
The first end of the Q3 is connected with the positive pole of the input power supply, the second end of the Q3 is connected with the second end of the Q4, and the first end of the Q4 is connected with the negative pole of the input power supply. Meanwhile, second ends of the Q3 and the Q4 are connected to be used as output ends of the push-pull unit; and control terminals of the Q3 and the Q4 are connected to serve as input terminals of the push-pull unit.
As shown in fig. 2, the first unidirectional conducting device may employ a diode D3, the voltage regulator device may employ a voltage regulator DZ1, and a first resistor R3.
Wherein, R3 and DZ1 are connected in series, one end of R3 is connected with the first end of Q1, the other end of R3 is connected with the negative electrode of DZ1, and the positive electrode of DZ1 is connected with the second end of Q1. The common terminal of R3 and DZ1 is connected as the output terminal of the first drive unit 2 to the control terminal of Q2.
The negative pole of D3 is connected to the first end of Q1, the positive pole of D3 is connected to the common end of R3 and DZ1, and D3 is used for unidirectional conduction. The first end of the Q1 is denoted as the point A, the second end of the Q1 is denoted as the point B, and the function of the D3 is to prevent the voltage at the point A from directly acting on the control end of the Q2 when the voltage at the point A is higher than that at the point B.
The following describes the operation of the driving circuit provided in this embodiment:
when the input power is powered on, an output pin OUT of the first PWM signal generation unit 11 outputs a PWM signal wave with fixed frequency and fixed duty ratio;
when the output pin OUT is at high level, Q3 is turned on, the output voltage of the push-pull unit is approximately equal to the voltage Vin of the input power supply, i.e. the push-pull unit outputs high level, Q1 is turned on, and the voltage of the point A is pulled down, i.e. VABIs low level; at this time, the cathode voltage of the DZ1 is low, the DZ1 is in an off state, the first driving unit outputs low, and the Q2 is turned off; at this time, the push-pull transformer supplies energy to the load through D1.
When the output pin OUT is at low level, Q4 is turned on, the output voltage of the push-pull unit is approximately equal to 0, namely the push-pull unit outputs low level, Q1 is turned off, and at this time, the voltage at the point A is approximately equal to the voltage Vin of the input power supply, so VABIs at a high level; at this time, the voltage regulator tube DZ1 works in a reverse voltage-stabilizing state, and the voltage of the control end of the Q2 is clamped at a certain voltage, namelyThe negative electrode of the DZ1 outputs high level, and Q2 is conducted; at this time, the push-pull transformer supplies energy to the load through D2. The alternating conduction of Q1 and Q2 maintains the output voltage constant.
According to the working process, the driving control of the Q2 can be realized by selecting the voltage stabilizing tube with proper voltage stabilizing parameters.
It should be noted that, the first PWM signal generating unit 11 may also be implemented by using other chips or circuits capable of outputting PWM signals; meanwhile, the first driving circuit 2 may be implemented by using other circuits capable of ensuring that the voltages at the two points AB are in the same phase with the gate-source voltage of Q2.
In addition, in the present embodiment, Q1 and Q2 may be implemented by NMOS transistors, and in other application scenarios, other types of switching transistors may be used, which is not limited in the present application.
According to the drive circuit of the push-pull switching power supply, the first drive unit adopts the common resistor, the common voltage regulator tube and the common diode, and compared with the phase inverter and the push-pull unit, the cost is greatly reduced. In addition, the first PWM signal generating unit is also realized by a chip with very low cost, so that the hardware cost of the whole driving circuit is reduced.
Referring to fig. 3, a circuit diagram of another push-pull switching power supply according to an embodiment of the present disclosure is shown, in which the first driving unit 2 mainly includes a resistor R3, a resistor R4, and a diode D3; the rest is the same as the embodiment shown in fig. 2.
When the OUT pin is at high level, Q3 is turned on, the push-pull unit outputs high level, Q1 is turned on, and V is at the momentABLow, the output of the first driving unit 2 is low, and Q2 is turned off; at this time, the push-pull transformer supplies energy to the load through D1;
when the OUT pin is at low level, Q4 is turned on, the push-pull unit outputs low level, Q1 is turned off, and at the moment, VABAt a high level, R3 and R4 divide the voltage, the dividing ratio of R3 and R4 is set according to the driving voltage of Q2, the voltage on R4 is the output voltage of the first driving unit 2, Q2 is turned on, and the push-pull transformer supplies energy to the load through D2; q1 and Q2 are alternately turned on to maintain the output voltage constant.
It should be noted that the first driving unit 2 in the present embodiment is not limited to be implemented by using a resistor composed of a resistor and a diode, and may be implemented by using another circuit capable of making the voltage at the point AB and the gate-source voltage of Q2 in the same phase.
In the driving circuit of the push-pull switching power supply provided by the embodiment, the first driving unit is realized by adopting the resistor and the diode with very low cost, and the cost is very low compared with the inverter and the push-pull unit. The hardware cost of the whole drive circuit is greatly reduced.
Referring to fig. 4, a schematic circuit diagram of another push-pull switching power supply according to an embodiment of the present disclosure is shown, in which the PWM signal driving unit 1 is implemented by using a second PWM signal generating unit 13. The driving capability of the PWM signal output by the second PWM signal generating unit 13 is sufficient to drive the switching tube.
In this embodiment, the second PWM signal generating unit is implemented by using a UCC2844 chip, a VCC pin of the UCC2844 is connected to a positive electrode of the input power supply, and an OUT pin is connected to a control terminal of the Q1 as an output terminal of the PWM signal driving unit 1. The frequency and duty ratio of the PWM signal output by the UCC2844 can be set according to actual requirements.
When an input power supply is powered on, an output pin OUT of the UCC2844 chip outputs a PWM signal wave with set frequency and set duty ratio, wherein the PWM signal output by the UCC2844 can directly drive the Q1 to be switched on or switched off; therefore, an amplification unit, for example, a push-pull unit, does not need to be additionally provided.
As shown in fig. 4, the first driving unit 2 in the present embodiment may be implemented by using a diode D3, a resistor R3, and a voltage regulator DZ 1. The working process of the first driving unit 2 in such an application scenario can refer to the working process of the first driving unit in the embodiment shown in fig. 2, and is not described herein again.
In addition, in other embodiments of the present application, as shown in fig. 5, the first driving unit may be implemented by using D3, a resistor R3, and a resistor R4, and the working process of the first driving unit 2 in such an application scenario may refer to the working process of the first driving unit in the embodiment shown in fig. 3, which is not described herein again.
The driving circuit of the push-pull switching power supply provided by this embodiment utilizes the PWM generating chip with sufficient driving capability to generate the PWM signal to drive the Q1 to turn on or off, and does not need to provide a unit for amplifying the PWM signal, thereby reducing the circuit complexity and the control complexity.
Referring to fig. 6, a schematic circuit diagram of another push-pull switching power supply according to an embodiment of the present disclosure is shown, in which a PWM signal driving unit in the present embodiment uses a PWM generating chip (e.g., UCC2844) having a current limiting function, and in this application scenario, the driving circuit may further include a current detecting unit 3.
The current detection unit 3 is used for sampling the current flowing in the main power loop and providing the sampled electric signal to a PWM generation chip with a current limiting function, so that the PWM generation chip limits the duty ratio of the output PWM signal.
Both Q1 and Q2 are connected in series in the main power loop, so the current detection unit 3 can be connected in series in the branch of Q1 or the branch of Q2, which is exemplified as being connected in series at the second end of Q2 in this embodiment. As shown in fig. 6, the detection terminal of the current detection unit 3 is connected to the CS pin of the UCC 2844.
In an embodiment of the present application, the current detecting unit 3 may be implemented by using a third resistor R5, wherein one end of the R5 is connected to the second end of the Q2, and the other end of the R5 is connected to the negative pole of the input power. One end of the R5 connected with the Q2 is connected with a CS pin of the UCC2844, and the R5 converts the current flowing through the Q2 into a voltage signal to be provided for the UCC2844 chip.
When the current in the main power loop of the push-pull switching power supply is increased, the current flowing through the Q2 is increased, the voltage on the resistor R5 is increased, and if the voltage on the R5 is larger than a preset voltage threshold value, the overcurrent phenomenon in the main power loop is determined; at this time, the duty ratio of the PWM signal output from the PWM generation chip (e.g., UCC2844 chip) is maintained at a certain constant value, thereby preventing the circuit from being damaged due to an excessively large duty ratio of the PWM signal.
The predetermined voltage threshold is determined by the PWM generation chip, for example, the UCC2844 chip provides the predetermined voltage threshold as 1V. Then, the resistance of R5 is selected according to the preset voltage threshold and the actual current limiting requirement.
It should be noted that the PWM signal driving unit of the present embodiment may adopt any chip capable of generating a PWM signal and having a current limiting function, and is not limited to the UCC 2844.
The driving circuit of the push-pull switching power supply provided by the embodiment adopts the PWM generating chip with the current limiting function, and when it is detected that the current in the main power loop of the push-pull switching power supply exceeds the set current value, the duty ratio of the output PWM signal is kept to be the preset duty ratio, so as to prevent the circuit damage caused by the overlarge duty ratio of the PWM signal generated when the current in the main power loop is overlarge.
It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the device-like embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The steps in the method of the embodiments of the present application may be sequentially adjusted, combined, and deleted according to actual needs.
The device and the modules and sub-modules in the terminal in the embodiments of the present application can be combined, divided and deleted according to actual needs.
In the several embodiments provided in the present application, it should be understood that the disclosed terminal, apparatus and method may be implemented in other manners. For example, the above-described terminal embodiments are merely illustrative, and for example, the division of a module or a sub-module is only one logical division, and there may be other divisions when the terminal is actually implemented, for example, a plurality of sub-modules or modules may be combined or integrated into another module, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules or sub-modules described as separate parts may or may not be physically separate, and parts that are modules or sub-modules may or may not be physical modules or sub-modules, may be located in one place, or may be distributed over a plurality of network modules or sub-modules. Some or all of the modules or sub-modules can be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, each functional module or sub-module in the embodiments of the present application may be integrated into one processing module, or each module or sub-module may exist alone physically, or two or more modules or sub-modules may be integrated into one module. The integrated modules or sub-modules may be implemented in the form of hardware, or may be implemented in the form of software functional modules or sub-modules.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A drive circuit for a push-pull switching power supply, comprising: a PWM signal driving unit and a first driving unit;
the output end of the PWM signal driving unit is connected with the control end of a first switching tube in the push-pull switching power supply and is used for generating a PWM driving signal for controlling the switching state of the first switching tube;
the first driving unit is connected between the first end and the second end of the first switch tube in parallel, the output end of the first driving unit is connected with the control end of a second switch tube in the push-pull switch power supply, and the first driving unit controls the switching state of the second switch tube by using the voltage at the two ends of the first switch tube;
the first end of the first switching tube is connected with a non-homonymous end of a second primary winding of a push-pull transformer in the push-pull switching power supply, the second end of the first switching tube is connected with the negative electrode of an input power supply, and the control end of the first switching tube is connected with the output end of a PWM signal driving unit in the driving circuit;
the first end of the second switching tube is connected with the dotted end of the first primary winding of the push-pull transformer, the second end of the second switching tube is connected with the negative electrode of the input power supply, and the control end of the second switching tube is connected with the output end of the first driving unit in the driving circuit;
and the non-homonymous end of the first primary winding and the homonymous end of the second primary winding are connected and connected with the anode of the power supply.
2. The drive circuit according to claim 1, wherein the first drive unit includes: the device comprises a first unidirectional conducting device, a voltage stabilizing device and a first resistor;
one end of the first resistor is connected with the first end of the first switching tube, the other end of the first resistor is connected with one end of the voltage stabilizing device, and the other end of the voltage stabilizing device is connected with the second end of the first switching tube;
the common point of the first resistor and the voltage stabilizing device is connected with the control end of the second switching tube;
the negative pole of the first unidirectional conduction device is connected with the first end of the first switch tube, and the positive pole of the first unidirectional conduction device is connected with the common point of the first resistor and the voltage stabilizing device.
3. The driving circuit according to claim 2, wherein the voltage regulator device is a voltage regulator tube;
the negative electrode of the voltage-stabilizing tube is connected with the first resistor, and the positive electrode of the voltage-stabilizing tube is connected with the second end of the first switch tube.
4. The driving circuit according to claim 2, wherein the voltage stabilizing device is a second resistor;
one end of the second resistor is connected with the other end of the first resistor, and the other end of the second resistor is connected with the second end of the first switch tube.
5. The driving circuit according to claim 1, wherein the PWM signal driving unit has a current limiting function terminal, and the driving circuit further comprises a current detecting unit;
the current detection unit is connected in series with a branch circuit where the first switch tube or the second switch tube is located, a detection end of the current detection unit is connected with a current limiting function end of the PWM signal driving unit, and the current detection unit is used for sampling current flowing in a primary winding of the push-pull transformer;
and the PWM signal driving unit is also used for outputting a PWM signal with the duty ratio equal to the preset duty ratio after detecting that the voltage of the current limiting function end is higher than the preset voltage threshold value.
6. The driving circuit according to claim 5, wherein the current detection unit is a third resistor;
one end of the third resistor is connected with the second end of the first switching tube and the current-limiting function end of the PWM signal driving unit, and the other end of the third resistor is connected with the negative electrode of the input power supply.
7. The drive circuit according to any one of claims 1 to 6, wherein the PWM signal drive unit includes a first PWM signal generation unit and a second drive unit;
the output end of the first PWM signal generating unit is connected with the input end of the second driving unit;
the output end of the second driving unit is connected with the control end of the first switch tube, and the second driving unit is used for amplifying the PWM signal generated by the first PWM signal generating unit and then driving the first switch tube to be switched on or switched off.
8. The driving circuit according to claim 7, wherein the second driving unit comprises a third switching tube and a fourth switching tube with opposite polarities;
the first end of the third switching tube is connected with the positive electrode of the input power supply, the second end of the third switching tube is connected with the control end of the first switching tube after being connected with the second end of the fourth switching tube, the first end of the fourth switching tube is connected with the negative electrode of the input power supply, and the control end of the third switching tube is connected with the control end of the fourth switching tube and is connected with the output end of the first PWM signal generating unit.
9. The drive circuit according to any one of claims 1 to 6, wherein the PWM signal drive unit includes a second PWM signal generation unit;
the output end of the second PWM signal generating unit is connected with the control end of the first switch tube, and the second PWM signal generating unit is used for generating a PWM signal for driving the first switch tube to be switched on or switched off.
10. A push-pull switching power supply, comprising a first switching tube, a second switching tube, a push-pull transformer, an output unit, and a driving circuit of the push-pull switching power supply according to any one of claims 1 to 9;
the first end of the first switching tube is connected with the non-homonymous end of the second primary winding of the push-pull transformer, the second end of the first switching tube is connected with the negative electrode of the input power supply, and the control end of the first switching tube is connected with the output end of the PWM signal driving unit in the driving circuit;
the first end of the second switching tube is connected with the dotted end of the first primary winding of the push-pull transformer, the second end of the second switching tube is connected with the negative electrode of the input power supply, and the control end of the second switching tube is connected with the output end of the first driving unit in the driving circuit;
the common end of the first primary winding and the second primary winding is connected with the positive electrode of the input power supply, wherein the non-homonymous end of the first primary winding and the homonymous end of the second primary winding are connected as the common end;
the dotted terminal of the first secondary winding of the push-pull transformer is connected with the anode of a first one-way conduction device, and the cathode of the first one-way conduction device is connected with the anode of the output unit;
the non-dotted terminal of a second secondary winding of the push-pull transformer is connected with the anode of a second one-way conduction device, and the cathode of the second one-way conduction device is connected with the anode of the output unit;
and the common end of the first secondary winding and the second secondary winding is connected with the negative electrode of the output unit, wherein the non-homonymous end of the first secondary winding and the homonymous end of the second secondary winding are connected to be used as the common end.
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| CN111799993A (en) * | 2019-04-08 | 2020-10-20 | 华润矽威科技（上海）有限公司 | Driving circuit |
| CN111800010A (en) * | 2019-04-08 | 2020-10-20 | 华润矽威科技（上海）有限公司 | Switching power supply circuit |
| CN111799991B (en) * | 2019-04-08 | 2023-06-09 | 华润微集成电路(无锡)有限公司 | Chip power supply circuit |
| CN111193412B (en) * | 2020-02-10 | 2023-07-07 | 普罗纳新能源(广东)有限公司 | Automatic uninterrupted power supply dual-power supply system |
| CN112503231B (en) * | 2020-11-03 | 2023-02-28 | 西安领创电子科技有限公司 | Electromagnetic valve, electromagnetic valve control system and method |
| CN116945768A (en) * | 2023-07-04 | 2023-10-27 | 沧州铭洋自动化技术有限公司 | Corrugated board digital printer control system |
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