CN106130355B - The transistor driving control method and controller of push-pull converter - Google Patents
The transistor driving control method and controller of push-pull converter Download PDFInfo
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- CN106130355B CN106130355B CN201610662849.4A CN201610662849A CN106130355B CN 106130355 B CN106130355 B CN 106130355B CN 201610662849 A CN201610662849 A CN 201610662849A CN 106130355 B CN106130355 B CN 106130355B
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Classifications
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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
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Abstract
The present invention relates to a kind of push-pull converters, in particular to the transistor driving control method and its controller of push-pull converter.Wherein, a kind of transistor driving controller of push-pull converter, suitable for the drive control to two push-pull transistors, including quasi- complementary pulse width generator, quasi- complementation pulse width generator generates the quasi- complementary clock signal of two-way, and clock signal controls the first transistor all the way, another way clock signal controls second transistor, to carry out its sharp push-pull type drive control of two push-pull transistors.Compared with prior art, the present invention in normal operation, transistor be it is sufficiently conductive, do not influence the working efficiency of push-pull converter.In rigid starting and when converter output short-circuit; since transformer primary winding is lost by clamped the effect of inductance; transistor both ends are superimposed biggish voltage, and this state, which is consecutively detected, will enter guard mode, avoid and are burned under high-voltage large current.
Description
Technical Field
The present invention relates to a push-pull converter, and more particularly, to a transistor driving control method and a controller for a push-pull converter.
Background
The push-pull converter has simple circuit structure, the transformer is excited in two directions during working, and the utilization rate of the magnetic core is high, so the converter has the advantages of small volume, high efficiency and good dynamic response, and is widely applied to occasions where low-voltage input, large-current output and input and output need to be electrically isolated.
The circuit shown in fig. 1 is a common self-excited push-pull converter in the prior art, and adopts a ROYER circuit structure, an input filter capacitor C1 is connected between a voltage input terminal Vin and a ground Gnd to filter an input voltage, the filtered input voltage is connected to a soft start circuit composed of a resistor R1 and a capacitor C2, the resistor R1 is connected in series with the capacitor C2 and then grounded, and two ends of a resistor R1 are respectively connected to the voltage input terminal Vin and center taps of primary side coils Nb1 and Nb2 of a coupling transformer T1 for providing positive feedback for bases of two push-pull transistors TR1 and TR 2; the emitters of the two push-pull transistors TR1 and TR2 are grounded, two collectors of the two push-pull transistors are respectively connected with two terminals of a primary coil Np1 and Np2 of the coupling transformer T1, bases of the two push-pull transistors are connected with two terminals of primary coils Nb1 and Nb2 of the coupling transformer T1, and a center tap of the primary coils Np1 and Np2 is connected with a voltage input terminal Vin; the anodes of the output rectifier diodes D1 and D2 are respectively connected with the two ends of the secondary windings Ns1 and Ns2 of the coupling transformer T1, the cathodes thereof are connected with the output end Vo +, the center taps of the secondary windings Ns1 and Ns2 of the coupling transformer T1 are connected with the output end Vo +, C3 is an output filter capacitor, and the two ends thereof are respectively connected between the output ends Vo + and Vo-.
The self-excited push-pull converter utilizes the saturation characteristics of the triode and the magnetic core to realize self-oscillation, when a power supply Vin is switched on, due to the action of the soft start circuit, the base voltages of the transistors TR1 and TR2 rise slowly, at the moment, the push-pull circuit cannot work immediately, and the self-excited push-pull converter has the function of avoiding larger input surge current caused by simultaneous instantaneous charging of the input filter capacitor at the moment of starting and starting of the push-pull circuit.
When the voltage of the soft-start capacitor C2 rises to the turn-on voltage of the bases of the transistors TR1 and TR2, the transistors TR1 and TR2 both obtain forward bias and tend to turn on, but because of a certain difference between the two transistors, a larger current must flow through one of the transistors. Assuming that the current flowing through TR1 is large, the collector current Ic1 flowing through the primary coil Np1 of the coupling transformer T1 magnetizes the magnetic core of the transformer, and an induced electromotive force is generated in other coils, as known from the transformer principle, at this time, two ends of the primary coil Nb2 will induce a "negative-up and negative-down positive" voltage, which is the same as the power supply voltage, so that TR1 obtains a large base current, and TR1 tends to be more on, similarly, two ends of the primary coil Nb1 also induce a "negative-up and negative-down positive" voltage, which is opposite to the power supply voltage, thereby inhibiting the on of TR2 and slowly tending to turn off.
As the conduction time increases, the induced electromotive force of the primary winding Nb2 will further increase the collector current of TR1 and quickly saturate TR1, and the conduction voltage drop of the transistor TR1 drops to a minimum value, it is considered that the input voltage Vin will be applied across the primary winding Np1, and thus the current flowing through the primary winding Np1 and the magnetic flux generated thereby will also increase linearly. When the magnetic core of the coupling transformer T1 approaches or reaches its saturation value, the rate of change of the magnetic flux approaches zero, the collector current of the transistor TR1 will increase sharply to generate a current spike, and the induced voltage on the primary winding Nb2 will decrease to reduce the base current of the transistor TR1, and the transistor TR1 exits the saturation region and enters the amplification region, and the collector current decreases rapidly. At this time, the induced voltages on all windings of the coupling transformer T1 will be reversed, and the transistor TR1 will be rapidly turned from the amplification state to the cutoff state, and at the same time, as can be seen from the analysis of the same-name ends of the windings in fig. 1, the induced voltages on all windings of the coupling transformer T1 are reversed, and the condition that the transistor TR2 rapidly turns on and saturates is just met. The working process is continuously repeated to form self-oscillation.
The above is the basic operating principle of the prior art self-excited push-pull converter, and the oscillation frequency of the circuit is a function of the power supply voltage and can be expressed as:
in the formula: f is oscillation frequency, Bw is work magnetic induction (T), N is the number of turns of the coil, and S is the effective sectional area of the magnetic core.
In general, in practical application, the self-oscillation frequency under the steady-state operation is generally set below 300 KHz. However, in the prior art, the self-excited push-pull converter has the following disadvantages:
1. high-frequency oscillation occurs in the starting process, and the starting current is large. Taking fig. 1 as an example, although the prior art scheme has a soft start function, it only performs a delay process to time-share the energy required for charging the input capacitor at the start moment and the energy required for the start process of the push-pull circuit, but it is essentially impossible to solve the problem of large start current in the start process of the push-pull circuit. In the prior art, when the circuit is started, because the initial voltage of an output capacitor is zero, secondary windings Ns1 and Ns2 of a coupling transformer are clamped by the voltage of the output capacitor, the circuit cannot enter a normal self-excited oscillation state when the circuit is started, high-frequency resonance is generated through leakage inductance and parasitic capacitance existing in the coupling transformer, and the resonance frequency is close to the characteristic frequency of a transistor, so that the collector currents of the transistors TR1 and TR2 are extremely high at the moment of starting, enough margin needs to be reserved during circuit design, and the reliability of the transistor is difficult to guarantee.
In the chinese patent publication No. CN102082526A entitled "a self-excited push-pull converter", paragraphs 0013 to 0016 also illustrate the major disadvantages of the prior art during start-up, and propose a method for controlling high-frequency oscillation during start-up by connecting a capacitor in parallel between the two collectors of the transistors TR1 and TR 2. However, in practical application, the capacitor cannot be set too large, so that the oscillation frequency generated in the starting process can only be controlled to be above 1 MHz.
2. The output belt has poor capacitive load capacity and poor reliability of the short-circuit protection function. If the value of the output capacitor C3 is too large, when the transformer is started, the initial voltage of the output capacitor C3 is zero, the output end is equivalent to a short circuit, a secondary coil of the coupling transformer is clamped by the output capacitor, so that the circuit cannot enter a normal self-oscillation state, the circuit generates high-frequency resonance through leakage inductance and parasitic capacitance of the transformer at the moment and is limited by the working frequency of a magnetic core, the transmission efficiency of the coupling transformer is extremely low in the process, and the output end cannot provide large current to enable the voltage of the output capacitor to rise rapidly. Under the condition of light load, the output voltage is slowly increased, and the starting time is long; when the load is large, the start-up is poor.
The output short-circuit protection is an important function of the switching power supply converter, and the input power consumption generated by the short-circuit protection directly determines the reliability of the whole system. The working process of the short circuit of the output end of the self-excitation push-pull type converter is basically the same as the process of starting the capacitive load of the output end, the circuit works in a high-frequency resonance state during the short circuit, and at the moment, extremely large working current exists in the collector electrodes of the transistors TR1 and TR2, the current can cause instantaneous heating of the transistors to damage the transistors, and the reliability of the whole circuit is influenced.
In the chinese patent publication No. CN102710110A entitled "short-circuit protection method for self-excited push-pull converter", a short-circuit protection implementation method for the existing self-excited push-pull converter is proposed, and this technique mainly adjusts the leakage inductance of the transformer and increases the capacitance of the starting capacitor to make the circuit work in an intermittent high-frequency oscillation state, so as to reduce the average input power consumption during the short-circuit protection process and improve the reliability of the circuit, and the specific working principle thereof will not be described again here. However, since the leakage inductance of the transformer needs to be adjusted according to actual conditions, the manufacturing requirement of the transformer is high, and the problems of low production efficiency, increased production cost and the like are caused in the case of large-scale mass production.
Disclosure of Invention
The invention aims to improve the reliability of the flyback push-pull converter, and provides a complete and reliable transistor driving control method of the flyback push-pull converter, so that the converter can carry out effective self-protection in an abnormal state.
Accordingly, another object of the present invention is to improve the reliability of its driving push-pull converter, and to provide a transistor driving controller of its driving push-pull converter.
The control method provided by the invention comprises the following steps:
a transistor drive control method of a push-pull converter is suitable for drive control of two push-pull transistors, and the transistor drive control method is a push-pull drive control method which generates two paths of quasi-complementary time sequence signals, wherein one path of time sequence signal controls the switch of a first transistor, and the other path of time sequence signal controls the switch of a second transistor.
The two quasi-complementary control signals mean that two timing signals are opposite in logic, namely one is in an active level, the other is in an inactive level, and the time when the two are in the active level is the same. There is a short time between the two active levels that they are simultaneously at the inactive level. The timing signal being at an active level is a necessary condition for the corresponding transistor to be turned on.
Detecting the conduction voltage drop of each transistor when the transistor is switched on, and if the conduction voltage drop is larger than a set value, enabling the controller to be in a current-limiting driving state and counting once; and if the conduction voltage drop is smaller than the set value, the controller enters a full driving state.
The current-limiting driving state means that the current passing through the transistor is limited within a reliable range due to the limited driving voltage when the transistor is turned on.
The full driving state means that the driving voltage of the transistor is high enough and is in a full conducting state when the transistor is switched on.
When the counting period number in the current-limiting driving state reaches a set value, the controller enters a protection state. At this point, the two transistors stop turning on and the timing of entering the protection state begins. And when the timing is finished, the controller is awakened again, and the two transistors are driven complementarily.
Further, the present invention provides a push-pull controller according to the control method, comprising: the circuit comprises a quasi-complementary pulse width generator, a first drive circuit, a second drive circuit, a drive power module, an output short circuit detection and protection module, a first transistor and a second transistor. A first port, a second port and a third port of the quasi-complementary pulse width generator are respectively connected with a first port of the first drive circuit, a first port of the second drive circuit and a first port of the output short-circuit detection and protection module; a second port, a third port and a fourth port of the output short circuit detection and protection module are respectively connected with a second port of the second transistor, a first port of the driving power supply module and a second port of the first transistor; the second port and the third port of the driving power supply module are respectively connected with the third port of the second driving circuit and the third port of the first driving circuit; the second port of the first driving circuit is connected with the third port of the first transistor; the second port of the second driving circuit is connected with the third port of the second transistor; the first port of the first transistor is connected to the first port of the second transistor.
The invention also provides a transistor driving controller of the push-pull converter, which is suitable for driving and controlling two push-pull transistors and comprises a quasi-complementary pulse width generator and a quasi-complementary pulse width generator, wherein two quasi-complementary time sequence signals are generated by the quasi-complementary pulse width generator, one time sequence signal controls the first transistor, and the other time sequence signal controls the second transistor so as to carry out other-excitation push-pull type driving control of the two push-pull transistors.
Preferably, the transistor driving controller of the push-pull converter further comprises a detection driving module, which starts to detect the conduction voltage drop of the transistor when receiving the timing signal of the quasi-complementary pulse width generator, and performs current-limiting driving \ full driving control of the transistor according to the comparison result of the detection values.
Preferably, the detection driving module counts the duration period of the current-limiting driving state, and performs holding/switching control of the transistor current-limiting driving according to the counting result; the switching current-limiting driving control enters into the protection mode control, and the protection mode control is to stop the output of the time sequence signal of the quasi-complementary pulse width generator, namely to stop the starting of the transistor.
Preferably, the detection driving module counts the stop time of the protection mode state, and performs the holding/resetting control of the transistor protection mode according to the timing result; and resetting restores the output of the timing signal of the quasi-complementary pulse width generator.
Preferably, the current-limiting driving of the transistor means that the driving power supplied to the transistor is limited to be low so that the transistor is in a current-limiting operating state. The current-limiting driving state is that the driving power when the transistor is turned on is limited, so that the current passing through the transistor is limited within the range of the device safe area.
Preferably, the sufficient driving of the transistor means that the driving power supplied to the transistor is sufficiently high to make the transistor in a sufficiently conductive state. The fully driven state is when the transistor is operating in the switched state.
Drawings
FIG. 1 is a circuit schematic of a prior art self-excited push-pull converter;
fig. 2 is a circuit diagram of a power portion of a conventional push-pull converter;
FIG. 3 is an idealized drive waveform diagram for a push-pull converter power tube;
fig. 4 is a control flowchart of the push-pull converter of the first embodiment of the present invention;
fig. 5 is a schematic block circuit diagram of a transistor drive controller of the push-pull converter according to the first embodiment of the present invention;
fig. 6 is a schematic circuit block diagram of a transistor driving controller of a push-pull converter according to a second embodiment of the present invention.
Detailed Description
Before explaining two embodiments of the present invention in detail, the related art mentioned in the background section is explained with reference to the accompanying drawings, so as to lead out the inventive concept of the present invention.
The circuit shown in fig. 1 is a common self-excited push-pull converter in the prior art, and a ROYER circuit structure is adopted, so that the normal operation of a transistor (or called a power tube) is difficult to ensure in the starting process, the capacitive load and the short-circuit protection of the self-excited push-pull converter, and the converter cannot enter a normal self-excited oscillation state easily.
In view of the shortcomings of the self-excited push-pull converter, an attempt is made to replace the existing self-excited push-pull control strategy with a separately-excited push-pull control strategy.
As shown in fig. 2, the main power circuit of the push-pull converter is used to excite the basic operation principle of the push-pull control: the driving waveforms of the gates Gate1 and Gate2 of the two power MOS transistors are as shown in fig. 3, Gate1 is turned on in the period from t2 to t3, Gate2 is turned on in the period from t4 to t5, the two on periods have the same duration, and the two power MOS transistors are not turned on for a short time period from t3 to t4 between the two on periods. That is, the drive levels are quasi-complementary in timing, i.e., one tube is on while the other is off, but there is a small dead time at the crossover of the switches to ensure that the two tubes do not conduct at the same time and that current back-flow occurs. When NM1 is turned on, transformer winding NS2 induces an electromotive force to charge the output capacitor through diode D2; conversely, when NM2 is turned on, transformer winding NS1 induces an electromotive force to charge the output capacitor through diode D1. This is repeated to obtain a required power supply at the secondary side of the power converter.
However, this type of push-pull converter has a serious disadvantage in that, since there is no voltage across the output capacitor Co during the initial startup and output short-circuit, the primary windings NP1 and NP2 of the transformer are clamped by the secondary side, i.e., they can no longer bear any excess voltage across them. Assuming NP 1-NP 2-NS 1-NS 2, the primary power tube is turned on when the output voltage is zero, and the voltage magnitude borne by the transformer is (NP1/NS1) -VBE, where VBE is the turn-on voltage drop of the output diode VD1 (or VD2), and is about 0.7V. When the power tube is conducted, the voltage of the drain electrode of the power tube is Vin-VBE which is 5V-0.7V which is 4.3V, obviously, the power tube works in an amplification region, so that the power tube has large heat productivity through very large saturation current, and is easy to damage when starting or outputting short circuit.
In view of the fact that the control flow of the whole converter is not operated according to the control flow designed theoretically but in an uncertain out-of-control state in a small dead time at the switching crossing of the two power tubes of the self-excited and separately excited push-pull converter, the converter presents various random and changeable external bad phenomena. The current push-pull converter improvements are aimed at a specific undesirable phenomenon, and the improvement result is to improve a specific undesirable problem and to make another new problem, but the fundamental problem of the transistor control strategy behind the undesirable phenomena causing the whole push-pull converter is not recognized.
That is to say, the circuit topology of the existing push-pull converter is mature, each device plays its own role, and it is difficult to realize the systematic optimization of the whole converter through the improvement of the local structure of the device and the circuit. If the circuit structure of the existing converter cannot be recognized and structural thinking is broken through, the problem of systematic control strategy behind each specific adverse phenomenon is difficult to find.
The invention is an improvement based on the discovery of systematic control strategy problems after breaking through structural thinking, and the basic improvement idea is to start from the control strategy of the circuit bottom layer, and adopt a clear and reliable separately excited push-pull control strategy to replace the existing self-excited push-pull control strategy so as to completely eliminate the out-of-control state of two power tubes at the switching crossing position, thereby fundamentally perfecting the operation order of the converter and forming a clear, orderly, reliable and complete set of control flow.
According to the idea, the transistor drive based on the push-pull converter is firstly used for carrying out the drive control of the push-pull converter, the drive control of the push-pull converter is carried out, two quasi-complementary time sequence signals are generated, one time sequence signal controls the first transistor, and the other time sequence signal controls the second transistor. And then through the detection driving module, when a time sequence signal of the quasi-complementary pulse width generator is received, the conduction voltage drop of the transistor is started to be detected, and current-limiting driving \ full driving control of the transistor is carried out according to a comparison result of detection values.
In order to make the invention more clearly understood, the invention is further described in detail below with reference to the attached drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example one
In order to make it easier to understand the transistor driving control method of the push-pull converter of the present invention, the present embodiment uses a control flow chart to describe the control process in detail, as shown in fig. 4, it is easy to see that there are 3 cycle states, which are in different cycle states under different operating conditions:
when the voltage of the output capacitor is zero at the moment of starting the converter, the converter firstly enters a first cycle state, namely: starting → selecting the current-limiting driving mode → determining the power tube driving mode as the current-limiting driving mode → driving the selected power tube in the current-limiting driving mode → detecting the conduction voltage drop of the power tube → judging that the voltage drop is larger than the set value → recording that the overvoltage frequency is increased by 1 time → the frequency does not exceed the set value → selecting the current-limiting driving again, and the steps are repeated. Wherein the power transistor is preferably a transistor.
If the output of the converter is not short-circuited, the voltage of the output capacitor is gradually increased in the continuous cyclic charging, and when the conduction voltage drop of the power tube is smaller than a set value, the converter enters a second cyclic state, namely: judging that the conduction voltage drop of the power tube is less than a set value → changing the driving mode into full driving → determining that the driving mode of the power tube is full driving → driving the selected power tube according to the full driving mode → detecting the conduction voltage drop of the power tube → the conduction voltage drop is less than the set value, and repeating the steps. The power tube is fully driven in the normal working state of the converter after starting, namely the power tube works in the switching state, the on-resistance is small, the loss is small, and the efficiency is high.
If the output of the converter is in a short-circuit state, and the conduction voltage drop of the power tube is always detected to be larger than a set value in a first circulation state, the overvoltage times are inevitably larger than the set value, the power tube is stopped to be driven, the time for stopping driving the power tube is recorded, the power tube is restarted after the timing is finished, and then the power tube enters the first circulation state again. It can be seen that if the output short-circuit condition is always present, the converter will operate in the third cycle, namely: first, the first circulation operating state is entered → until the number of times of overpressure exceeds a set value → the driving is stopped and timed (rest state) → the first circulation operating state is entered again, thus continuously circulating.
Sufficient charging time is provided for the output capacitor in the first cycle state, so that the phenomenon that the output capacitor is mistakenly considered as an output short circuit due to too low voltage when the machine is just started, and the machine starting is abnormal is avoided; meanwhile, the power tube works in a current-limiting driving state all the time in the first circulation state, and the current-limiting driving state is that the driving voltage is limited when the power tube is switched on, so that the current passing through the power tube is limited within the range value of a safety area of the device, and the overcurrent impact and excessive heating of the device are avoided; the safe area range value is determined according to the parameters of the weakest device on the current path, and the power tube is a key device, namely a vulnerable device, on the current path of the converter, therefore, the current-limiting drive of the converter is often designed according to the safe area range value of the power tube, but if the circuit has special requirements, the weakest device on the current path can also be other devices. In the second circulation state, the power tube is always in a full driving state, namely the power tube works in a switching state, the conduction voltage drop is very small, and the efficiency of the converter is ensured. In the third cycle state, the heat generated in the first cycle working state is dissipated when the rest state is entered, and then the work is resumed again. The three circulation states can be switched without dead angles, and the first circulation state and the third circulation state can be entered as long as the abnormal condition of output short circuit occurs; when the abnormal condition disappears, the second circulation state is automatically recovered. The reliability of the converter is comprehensively ensured, and the performance of the converter in normal operation is not influenced.
As shown in fig. 5, a dashed box 100 is a transistor driving controller of the push-pull converter of the present invention, and includes a quasi-complementary pulse width generator and a detection driving module connected between the quasi-complementary pulse width generator and a power tube, where the detection driving module includes an output short circuit detection and protection module, a driving power supply module, a driving circuit 1 and a driving circuit 2. And when receiving a time sequence signal of the quasi-complementary pulse width generator, the detection driving module starts to detect the conduction voltage drop of the transistor and performs current-limiting driving \ full driving control on the transistor according to a comparison result of detection values. The quasi-complementary pulse width generator comprises three ports 101, 102 and 103; the output short circuit detection and protection module comprises four ports 104, 105, 106 and 107; the driving power supply module comprises three ports 108, 109 and 110; the driving circuit 1 includes three ports 111, 112, 113; the driver circuit 2 comprises three ports 114, 115, 116. Also, there are two power tubes that each contain three ports. In this embodiment, the power transistor is an MOS transistor.
The connection relation and the function of each port are as follows: the port 101 is connected with the port 111, and the quasi-complementary pulse width generator selects the power tube 1 to be driven through the connecting line; the port 102 is connected with the port 114, and the quasi-complementary pulse width generator selects the power tube 2 to be driven through the connecting line; the port 103 is connected with the port 104, the output short circuit detection and protection module is informed to detect the voltage drop of which power tube through the connecting quasi-complementary pulse width generator, and when the output short circuit detection and protection module enters a protection state, the output short circuit detection and protection module informs the former to stop driving any power tube; the port 107 and the port 105 of the output short circuit detection and protection module are respectively connected with the second port of the power tube 1 and the second port of the power tube 2, and are used for detecting the conduction voltage drop of the two power tubes; the port 106 is connected to the port 108 for selecting the magnitude of the output voltage of the driving power module, and the voltage provided in the current limiting state is low, so that the power tube is in the current limiting conduction state, and the voltage provided in the full driving state is high enough, so that the power tube is fully conducted and the voltage drop is small.
The working principle of the controller of the invention is as follows: the quasi-complementary pulse width generator generates two quasi-complementary control signals, respectively controls the first driving circuit and the second driving circuit to output driving voltage to control the opening of the corresponding power tube, and simultaneously provides a control time sequence signal for the output short circuit detection and protection module. The output short circuit detection and protection module detects the conduction voltage drop of the corresponding power tube in the received control time sequence signal from the quasi-complementary pulse width generator, if the conduction voltage drop is smaller than a set value, the drive power supply module is controlled to provide high output voltage, and then the drive circuit outputs high enough voltage to fully conduct the power tube; if the conduction voltage drop is larger than the set value, the driving power supply module is controlled to provide low output voltage, so that the driving circuit cannot provide high enough voltage for the power tube, and the power tube is in a current-limiting working state. Counting once when the voltage drop of the power tube is detected to be larger than the set value every time, resetting the counter once the voltage drop of the power tube is detected to be smaller than the set value, entering a protection state if the voltage drop of the power tube is continuously detected to be larger than the set value within the set time, informing the quasi-complementary pulse width generator to stop outputting the complementary control signal, namely stopping starting the power tube, starting timing, and resuming the work of the quasi-complementary pulse width generator again after the timing is finished.
Therefore, under the normal working state, the power tube is fully conducted, and the working efficiency of the push-pull converter is not influenced. When the transformer is just started and the output of the converter is short-circuited, the primary winding of the transformer is clamped to lose the effect of the inductor, and larger voltage is superposed at two ends of the power tube, so that the power tube enters a protection state when the state is continuously detected, and the power tube is prevented from being burnt out under high voltage and large current. It should be noted that the protection state is not immediately entered when the conduction voltage drop of the power tube is detected to be greater than the set value, but only the power tube is in the current-limiting driving state, and the protection state is entered only when the conduction voltage drop is continuously detected to be too large within the set time. Because the voltage on the output capacitor is very small when the converter is just started, the conduction voltage drop of the power tube is inevitably larger than a set value, if the voltage drop is detected to be larger than the set value, the converter enters a protection state, the converter cannot be started with the output capacitor, and the protection cannot be triggered by mistake only by setting proper time to charge the capacitor enough. Although the protection state is not immediately entered during this time, the power tube is in the current-limiting driving state, and the generation of heat is restrained to a certain extent.
Example two
As shown in fig. 6, the portion of the dashed box 200 is the transistor driver controller of the push-pull converter of the present invention. Compared with the first embodiment, the present embodiment is different in that the driven power transistor is a triode. Because the transistor is a current-driven device, the corresponding driving power module becomes a driving current module, which provides a smaller driving current in the current-limited operating state and a sufficiently large driving current in the fully-driven state so that the conduction voltage drop of the transistor is sufficiently small.
Claims (4)
1. A transistor drive controller of a push-pull converter, adapted to drive control of two push-pull transistors, characterized in that: comprises a quasi-complementary pulse width generator and a detection driving module,
the quasi-complementary pulse width generator generates two quasi-complementary time sequence signals, one time sequence signal controls the first transistor, the other time sequence signal controls the second transistor, so as to carry out other-excitation push-pull type drive control of the two push-pull transistors;
the detection driving module is used for detecting the driving module,
when a time sequence signal of the quasi-complementary pulse width generator is received, starting to detect the conduction voltage drop of the transistor, and carrying out current-limiting driving \ full driving control on the transistor according to a comparison result of detection values;
in the current-limiting driving state, counting the continuous period of the current-limiting driving state, and keeping/switching control of the transistor current-limiting driving according to the counting result; switching the current-limiting drive control, namely entering a protection mode control, wherein the protection mode control is to stop the output of a time sequence signal of the quasi-complementary pulse width generator, namely to stop starting a transistor;
in the protection mode state, timing the stop time of the transistor, and performing the keeping/resetting control of the transistor protection mode according to the timing result; resetting and recovering the output of the time sequence signal of the quasi-complementary pulse width generator; wherein
The current-limiting driving of the transistor means that the driving electric quantity provided for the transistor is limited to be lower so as to enable the transistor to be in a current-limiting working state;
sufficient driving of the transistor means that the amount of driving power provided to the transistor is sufficiently high to place the transistor in a sufficiently conductive state.
2. The transistor drive controller of a push-pull converter according to claim 1, characterized in that: the detection driving module comprises a first driving circuit, a second driving circuit, a driving power module and an output short-circuit detection and protection module, and the specific connection relation between the detection driving module and the quasi-complementary pulse width generator is that a first port, a second port and a third port of the quasi-complementary pulse width generator are respectively connected with a first port of the first driving circuit, a first port of the second driving circuit and a first port of the output short-circuit detection and protection module; a second port, a third port and a fourth port of the output short circuit detection and protection module are respectively connected with a second port of the second transistor, a first port of the driving power supply module and a second port of the first transistor; the second port and the third port of the driving power supply module are respectively connected with the third port of the second driving circuit and the third port of the first driving circuit; the second port of the first driving circuit is connected with the third port of the first transistor; the second port of the second driving circuit is connected with the third port of the second transistor; the first port of the first transistor is connected to the first port of the second transistor.
3. A transistor drive control method of a push-pull converter is suitable for drive control of two push-pull transistors,
the transistor driving control method is a push-pull driving control method, and the push-pull driving control method is used for generating two paths of quasi-complementary time sequence signals, wherein one path of time sequence signal controls a first transistor, and the other path of time sequence signal controls a second transistor; the method comprises the following steps:
a detection control step, namely starting to detect the conduction voltage drop of the transistor when receiving the time sequence signal, and carrying out current-limiting driving \ full driving control on the transistor according to a comparison result of detection values;
a protection mode switching step of counting the continuous period in the current-limiting driving state and performing holding/switching control of the transistor current-limiting driving according to the counting result; switching the current-limiting drive control, namely entering a protection mode control, wherein the protection mode control is to stop outputting a time sequence signal, namely to stop starting a transistor;
a reset step of the protection mode, timing the stop time of the protection mode, and keeping/resetting control of the transistor protection mode according to the timing result; resetting and recovering the output of the time sequence signal; wherein,
the current-limiting driving of the transistor means that the driving electric quantity provided for the transistor is limited to be lower so as to enable the transistor to be in a current-limiting working state;
sufficient driving of the transistor means that the amount of driving power provided to the transistor is sufficiently high to place the transistor in a sufficiently conductive state.
4. The transistor drive control method of a push-pull converter according to claim 3, characterized in that: the two quasi-complementary time sequence signals refer to two logically opposite time sequence signals; the time of the two paths of time sequence signals in the effective level is the same, an interval time interval exists between the effective levels of the two paths of time sequence signals, and the two paths of time sequence signals in the interval time interval are in the ineffective level at the same time; the active level of the timing signal corresponds to the on drive control of the transistor.
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| CN106533187B (en) * | 2016-11-25 | 2018-12-11 | 广州金升阳科技有限公司 | Drive control method and circuit |
| CN108880271A (en) * | 2018-08-24 | 2018-11-23 | 广州致远电子有限公司 | A kind of push-pull converter circuit and its control method |
| CN108923662A (en) * | 2018-08-24 | 2018-11-30 | 广州致远电子有限公司 | A kind of push-pull converter circuit and its control method |
| CN109067164A (en) * | 2018-08-24 | 2018-12-21 | 广州致远电子有限公司 | A kind of push-pull converter circuit and its control method |
| CN108880272B (en) * | 2018-08-24 | 2024-06-21 | 广州致远电子股份有限公司 | Push-pull converter circuit and control method thereof |
| CN111082668A (en) * | 2018-10-22 | 2020-04-28 | 苏州源特半导体科技有限公司 | Inverter control method and drive controller |
| CN110601541A (en) * | 2019-09-10 | 2019-12-20 | 深圳南云微电子有限公司 | Control method and controller of full-bridge converter |
| CN111313661A (en) * | 2020-04-06 | 2020-06-19 | 苏州源特半导体科技有限公司 | Controller and protection method of switching power supply converter |
| CN111416512B (en) * | 2020-04-29 | 2021-06-11 | 深圳南云微电子有限公司 | Short circuit judgment and timing control method and circuit |
| CN112379204B (en) * | 2020-11-18 | 2024-03-29 | 苏州美思迪赛半导体技术有限公司 | Driving port state detection circuit and method of driving circuit |
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