CN207835344U - Full-bridge control circuit and full-bridge converter - Google Patents
Full-bridge control circuit and full-bridge converter Download PDFInfo
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- CN207835344U CN207835344U CN201820266722.5U CN201820266722U CN207835344U CN 207835344 U CN207835344 U CN 207835344U CN 201820266722 U CN201820266722 U CN 201820266722U CN 207835344 U CN207835344 U CN 207835344U
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Abstract
The utility model discloses a full-bridge control circuit and a full-bridge converter, which comprises a PWM signal modulation module, an isolation module and a full-bridge main circuit; the PWM signal modulation module is provided with a first signal input end, a second signal input end, a third signal input end, a fourth signal input end, a first logic output end and a second logic output end; the isolation module is provided with a first driving signal input end, a second driving signal input end, a third driving signal input end, a fourth driving signal input end and four driving signal output ends; the full-bridge main circuit is provided with a power input end, a power output end and four controlled ends, and each controlled end controls one switching tube of the full-bridge main circuit. The low tube modulation of the full-bridge main circuit is realized simply at low cost, the problem of large switching loss of the full-bridge converter is solved, and the working efficiency of the full-bridge converter is improved.
Description
Technical Field
The utility model belongs to full-bridge main circuit control field, concretely relates to full-bridge control circuit and full-bridge converter.
Background
The existing high-power switching power supply adopts a full-bridge conversion circuit, and because the common bipolar hard switching control mode of the full-bridge conversion circuit is simple and the realized circuit structure is simple, the existing full-bridge conversion circuit generally adopts the common bipolar hard switching control mode, as shown in fig. 1, the full-bridge conversion circuit is a structural schematic diagram of a hard switching full-bridge control circuit in the prior art. However, the control mode of hard switching adopted by the full-bridge conversion circuit can cause conduction loss, turn-on loss and turn-off loss of the topological power switch tube and charge and discharge loss of a junction capacitor of the switch tube in the working process and the turn-on and turn-off processes; when the operating frequency of the converter increases, the losses increase with increasing switching frequency, resulting in a reduction in the efficiency of the converter; and if the control method of the soft switch is adopted to control the full-bridge inverter circuit, the manufacturing cost of the full-bridge inverter is high due to the high manufacturing cost of the signal modulation chip on the market.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a full-bridge control circuit and full-bridge converter can realize the low tube modulation of full-bridge main circuit through the low cost, solves the big problem of full-bridge converter switching loss, improves the work efficiency of full-bridge converter.
In order to solve the above technical problem, an embodiment of the present invention provides a full-bridge control circuit, include: the device comprises a PWM signal modulation module, an isolation module and a full-bridge main circuit;
the PWM signal modulation module is provided with a first signal input end, a second signal input end, a third signal input end, a fourth signal input end, a first logic output end and a second logic output end; the isolation module is provided with a first driving signal input end, a second driving signal input end, a third driving signal input end, a fourth driving signal input end and four driving signal output ends; the full-bridge main circuit is provided with a power input end, a power output end and four controlled ends, and each controlled end controls one switching tube of the full-bridge main circuit;
the first signal input terminal is used for receiving a first PWM signal, and the fourth signal input terminal is used for receiving a second PWM signal; the first PWM signal is complementary to the second PWM signal; the first signal input end is connected with the fourth driving signal input end, the second signal input end and the second logic output end are both connected with the first driving signal input end, the third signal input end and the first logic output end are both connected with the third driving signal input end, and the fourth signal input end is connected with the second driving signal input end; the first logic output end is used for realizing NOR logic output according to signals received by the first signal input end and the second signal input end; the second logic output end is used for realizing NOR logic output according to signals received by the third signal input end and the fourth signal input end;
the isolation module is used for mapping and outputting four signals received by the driving signal input end of the isolation module to the four driving signal output ends one by one; the four driving signal output ends are connected with the four controlled ends in a one-to-one mapping mode.
Further, the PWM signal modulation module includes a first nor gate and a second nor gate; wherein,
a first input end of the first nor gate is connected with a first signal input end of the PWM signal modulation module, a second input end of the first nor gate is connected with a second signal input end of the PWM signal modulation module, and an output end of the first nor gate is connected with a first logic output end of the PWM signal modulation module; the first input end of the second nor gate is connected with the third signal input end of the PWM signal modulation module, the second input end of the second nor gate is connected with the fourth signal input end of the PWM signal modulation module, and the output end of the second nor gate is connected with the second logic output end of the PWM signal modulation module.
Further, the isolation module comprises a first driving chip and a second driving chip; the driving chip comprises a logic high-end input end HIN, a logic low-end input end LIN, a high-end output end Ho and a low-end output end Lo;
a logic high-end input end HIN of the first driving chip is connected with a first driving signal input end of the isolation module, a logic low-end input end LIN of the first driving chip is connected with a second driving signal input end of the isolation module, a high-end output end Ho of the first driving chip is connected with a first driving signal output end of the isolation module, and a low-end output end Lo of the first driving chip is connected with a second driving signal output end of the isolation module; a logic high-end input end HIN of the second driver chip is connected with a third driving signal input end of the isolation module, a logic low-end input end LIN of the second driver chip is connected with a fourth driving signal input end of the isolation module, a high-end output end Ho of the second driver chip is connected with a third driving signal output end of the isolation module, and a low-end output end Lo of the second driver chip is connected with a fourth driving signal output end of the isolation module.
Further, the full-bridge main circuit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the power supply output end of the full-bridge main circuit is provided with a first power supply output end and a second power supply output end;
the control end of the first switching tube is connected with the first controlled end of the full-bridge main circuit, the input end of the first switching tube is connected with the power input end of the full-bridge main circuit, and the output end of the first switching tube is connected with the first power output end of the full-bridge main circuit; the control end of the second switching tube is connected with the second controlled end of the full-bridge main circuit, the input end of the second switching tube is connected with the input end of the first switching tube, and the output end of the second switching tube is connected with the second power supply output end of the full-bridge main circuit; the control end of the third switching tube is connected with the third controlled end of the full-bridge main circuit, the input end of the third switching tube is connected with the output end of the second switching tube, and the output end of the third switching tube is grounded; the control end of the fourth switch tube is connected with the fourth controlled end of the full-bridge main circuit, the input end of the fourth switch tube is connected with the output end of the first switch tube, and the output end of the fourth switch tube is grounded.
Further, the full-bridge main circuit further comprises a first capacitor and a first inductor connected between the output end of the first switch tube and the first power output end of the full-bridge main circuit;
the first end of the first capacitor is connected with the input end of the first switch tube, and the second end of the first capacitor is grounded.
Preferably, the switch tube is an N-channel MOS tube;
the control end of the switch tube is a grid electrode of the N-channel MOS tube, the input end of the switch tube is a drain electrode of the N-channel MOS tube, and the output end of the switch tube is a source electrode of the N-channel MOS tube.
Further, the full-bridge main circuit also comprises a transformer;
the first end of the primary coil of the transformer is connected with the first power output end of the full-bridge main circuit, and the second end of the primary coil of the transformer is connected with the second power output end of the full-bridge main circuit.
Further, the transformer includes a first secondary coil and a second secondary coil; the full-bridge main circuit also comprises a rectifying and filtering module, and the rectifying and filtering module is provided with an output end; the rectifying and filtering module comprises a first diode, a second inductor and a second capacitor;
the anode of the first diode is connected with the first end of the first secondary coil, and the cathode of the first diode is connected with the first end of the second inductor; the second end of the second inductor is connected with the output end; the second capacitor is connected with the second end of the second inductor, and the second end of the second capacitor is grounded; a second end of the first secondary coil is connected with a second end of the second capacitor; the first end of the second secondary coil is connected with the second end of the second capacitor, the second end of the second secondary coil is connected with the anode of the second diode, and the cathode of the second diode is connected with the cathode of the first diode.
The embodiment of the utility model provides a still provide a full-bridge converter, include: the PWM generator, the direct current power supply and the full-bridge control circuit;
the PWM generator has a first PWM signal output terminal and a second PWM signal output terminal; the direct current power supply is provided with a direct current output end;
a first PWM signal output end of the PWM generator is connected with a first signal input end of the PWM signal modulation module, and a second PWM signal output end of the PWM generator is connected with a fourth signal input end of the PWM signal modulation module; and the direct-current output end of the direct-current power supply is connected with the power supply input end of the full-bridge main circuit.
Compared with the prior art, the utility model discloses a full-bridge control circuit and full-bridge converter's beneficial effect lies in: by arranging the PWM signal modulation module, the PWM signal modulation module receives two paths of complementary PWM signals through the first signal input end and the fourth signal input end, and the first logic output end of the PWM signal modulation module realizes NOR logic output according to the signals received by the first signal input end and the second signal input end; the second logic output end of the PWM signal modulation module realizes NOR logic output according to signals received by the third signal input end and the fourth signal input end, and converts two paths of PWM driving signals into four paths of PWM driving; and four PWM drive signals are mapped one by one through four drive signal input ends of the isolation module and output to the four drive signal output ends, and the four drive signal output ends of the isolation module are mapped one by one with four controlled ends of the full-bridge main circuit, so that the four PWM drive signals modulate a lower tube of the full-bridge main circuit, the problem of large switching loss of the full-bridge converter controlled by a hard switch is solved, and the switching frequency of a switching tube of the full-bridge converter is improved. Through mutual cooperation among the PWM signal modulation module, the isolation module and the full-bridge main circuit, the low-tube modulation full-bridge main circuit is simply realized at low cost, the stress of a switch tube is reduced, and the working efficiency of the full-bridge converter is improved.
Drawings
FIG. 1 is a schematic diagram of a hard-switched full-bridge control circuit in the prior art;
fig. 2 is a schematic structural diagram of an embodiment of a full-bridge control circuit provided by the present invention;
fig. 3 is a schematic circuit diagram of another embodiment of a full bridge control circuit provided by the present invention;
fig. 4 is a schematic structural diagram of a full-bridge converter provided by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Referring to fig. 2, it is a schematic structural diagram of an embodiment of a full-bridge control circuit provided in the present invention, the full-bridge control circuit includes: the PWM signal modulation module 10, the isolation module 20 and the full-bridge main circuit 30;
the PWM signal modulation module 10 has a first signal input terminal, a second signal input terminal, a third signal input terminal, a fourth signal input terminal, a first logic output terminal and a second logic output terminal; the isolation module 20 has a first driving signal input terminal, a second driving signal input terminal, a third driving signal input terminal, a fourth driving signal input terminal and four driving signal output terminals; the full-bridge main circuit 30 has a power input terminal, a power output terminal and four controlled terminals, and each controlled terminal controls one switching tube of the full-bridge main circuit 30;
the first signal input terminal is used for receiving a first PWM signal, and the fourth signal input terminal is used for receiving a second PWM signal; the first PWM signal is complementary to the second PWM signal; the first signal input end is connected with the fourth driving signal input end, the second signal input end and the second logic output end are both connected with the first driving signal input end, the third signal input end and the first logic output end are both connected with the third driving signal input end, and the fourth signal input end is connected with the second driving signal input end; the first logic output end is used for realizing NOR logic output according to signals received by the first signal input end and the second signal input end; the second logic output end is used for realizing NOR logic output according to signals received by the third signal input end and the fourth signal input end;
the isolation module 20 is configured to map and output four signals received by the driving signal input end of the isolation module 20 to the four driving signal output ends one by one; the four driving signal output ends are connected with the four controlled ends in a one-to-one mapping mode.
It should be noted that, the utility model provides a full-bridge control circuit, through setting up PWM signal modulation module, PWM signal modulation module receives two way complementary PWM signals through first signal input end and fourth signal input end, and the first logic output end of PWM signal modulation module realizes or not logical output according to the signal that first signal input end and second signal input end received; the second logic output end of the PWM signal modulation module realizes NOR logic output according to signals received by the third signal input end and the fourth signal input end, and converts two paths of PWM driving signals into four paths of PWM driving; and four PWM drive signals are mapped one by one through four drive signal input ends of the isolation module and output to the four drive signal output ends, and the four drive signal output ends of the isolation module are mapped one by one with four controlled ends of the full-bridge main circuit, so that the four PWM drive signals modulate a lower tube of the full-bridge main circuit, the problem of large switching loss of the full-bridge converter controlled by a hard switch is solved, and the switching frequency of a switching tube of the full-bridge converter is improved. Through mutual cooperation among the PWM signal modulation module, the isolation module and the full-bridge main circuit, the full-bridge main circuit is modulated by the lower tube in a simple and low-cost realization mode, the stress of the switch tube is reduced, and the working efficiency of the switch tube of the full-bridge conversion circuit is improved.
Fig. 3 is a schematic circuit diagram of another embodiment of a full-bridge control circuit according to the present invention.
On the basis of the above embodiments, the full-bridge control circuit provided in this embodiment further optimizes the structure of a part of functional circuits, specifically as follows:
further, the PWM signal modulation module 10 includes a first nor gate U3 and a second nor gate U4; wherein,
a first input terminal of the first nor gate U3 is connected to a first signal input terminal of the PWM signal modulation module 10, a second input terminal of the first nor gate U3 is connected to a second signal input terminal of the PWM signal modulation module 10, and an output terminal of the first nor gate U3 is connected to a first logic output terminal of the PWM signal modulation module 10; a first input terminal of the second nor gate U4 is connected to the third signal input terminal of the PWM signal modulation module 10, a second input terminal of the second nor gate U4 is connected to the fourth signal input terminal of the PWM signal modulation module 10, and an output terminal of the second nor gate U4 is connected to the second logic output terminal of the PWM signal modulation module 10.
Further, the isolation module 20 includes a first driver chip U1 and a second driver chip U2; the driving chip comprises a logic high-end input end HIN, a logic low-end input end LIN, a high-end output end Ho and a low-end output end Lo;
a logic high-end input terminal HIN of the first driver chip U1 is connected to a first driving signal input terminal of the isolation module 20, a logic low-end input terminal LIN of the first driver chip U1 is connected to a second driving signal input terminal of the isolation module 20, a high-end output terminal Ho of the first driver chip U1 is connected to a first driving signal output terminal of the isolation module 20, and a low-end output terminal Lo of the first driver chip U1 is connected to a second driving signal output terminal of the isolation module 20; a logic high-end input terminal HIN of the second driver chip U2 is connected to a third driving signal input terminal of the isolation module 20, a logic low-end input terminal LIN of the second driver chip U2 is connected to a fourth driving signal input terminal of the isolation module 20, a high-end output terminal Ho of the second driver chip U2 is connected to a third driving signal output terminal of the isolation module 20, and a low-end output terminal Lo of the second driver chip U2 is connected to a fourth driving signal output terminal of the isolation module 20.
Further, the full-bridge main circuit 30 includes a first switching tube Q1, a second switching tube Q2, a third switching tube Q3 and a fourth switching tube Q4; the power output end of the full-bridge main circuit 30 is provided with a first power output end and a second power output end;
the control end of the first switch tube Q1 is connected to the first controlled end of the full-bridge main circuit 30, the input end of the first switch tube Q1 is connected to the power input end of the full-bridge main circuit 30, and the output end of the first switch tube Q1 is connected to the first power output end of the full-bridge main circuit 30; the control end of the second switch tube Q2 is connected to the second controlled end of the full-bridge main circuit 30, the input end of the second switch tube Q2 is connected to the input end of the first switch tube Q1, and the output end of the second switch tube Q2 is connected to the second power output end of the full-bridge main circuit 30; the control end of the third switching tube Q3 is connected with the third controlled end of the full-bridge main circuit 30, the input end of the third switching tube Q3 is connected with the output end of the second switching tube Q2, and the output end of the third switching tube Q3 is grounded; the control end of the fourth switching tube Q4 is connected with the fourth controlled end of the full-bridge main circuit 30, the input end of the fourth switching tube Q4 is connected with the output end of the first switching tube Q1, and the output end of the fourth switching tube Q4 is grounded.
In the embodiment of the present invention, the first driving chip U1 and the second driving chip U2 in the isolation module 20 further have a high-end floating power offset voltage terminal Vs and a common terminal COM, and the high-end floating power offset voltage terminal Vs of the first driving chip U1 is connected to the output terminal of the first switch Q1 in the full-bridge main circuit 30; the high-side floating power offset voltage terminal Vs of the second driver chip U2 is connected to the output terminal of the second switch Q2; the common terminal COM of the first driving chip U1 and the second driving chip U2 are both grounded. A first driving signal output end of the isolation module 20 is connected to a first controlled end of the full-bridge main circuit to control the first switching tube; a second driving signal output end of the isolation module 20 is connected to a fourth controlled end of the full-bridge main circuit to control the fourth switching tube; a third driving signal output end of the isolation module 20 is connected to a second controlled end of the full-bridge main circuit to control the second switching tube; and a fourth driving signal output end of the isolation module 20 is connected with a third controlled end of the full-bridge main circuit to control the third switching tube. The four high-power PWM driving signals are isolated by the first driving chip U1 and the second driving chip U2 in the isolation module 20, and then the four low-power driving signals are outputted to control the four MOS switch transistors of the full-bridge main circuit, so as to prevent the switch transistors from being burned out due to the input of the high-power driving signals.
Further, the full-bridge main circuit 30 further includes a first capacitor C1 and a first inductor L1 connected between the output terminal of the first switch Q1 and the first power output terminal of the full-bridge main circuit 30;
the first end of the first capacitor C1 is connected to the input end of the first switch tube Q1, and the second end of the first capacitor C1 is grounded. Because the switching tube on the bridge arm of the full-bridge main circuit works in a switching state, voltage and current can generate higher harmonics after passing through the transformer to destroy the power supply quality of the power supply and cause serious interference to output, and the higher harmonics can be effectively filtered through the first capacitor C1 to realize a filtering effect.
Preferably, the switch tube is an N-channel MOS tube;
the control end of the switch tube is a grid electrode of the N-channel MOS tube, the input end of the switch tube is a drain electrode of the N-channel MOS tube, and the output end of the switch tube is a source electrode of the N-channel MOS tube.
Further, the full-bridge main circuit 30 further includes a transformer 40;
a first end of the primary coil of the transformer 40 is connected to the first power output end of the full-bridge main circuit 30, and a second end of the primary coil of the transformer 40 is connected to the second power output end of the full-bridge main circuit 30.
Further, the transformer 40 includes a first secondary coil and a second secondary coil; the full-bridge main circuit 30 further comprises a rectifying and filtering module 50, and the rectifying and filtering module 50 has an output end; the rectifying and filtering module 50 comprises a first diode D1, a second diode D2, a second inductor L2 and a second capacitor C2;
the anode of the first diode D1 is connected with the first end of the first secondary coil, and the cathode of the first diode D1 is connected with the first end of the second inductor L2; a second end of the second inductor L2 is connected to the output terminal; the second capacitor C2 is connected to the second end of the second inductor L2, and the second end of the second capacitor C2 is grounded; a second end of the first secondary winding is connected with a second end of the second capacitor C2; a first terminal of the second secondary winding is connected to a second terminal of the second capacitor C2, a second terminal of the second secondary winding is connected to an anode of the second diode D2, and a cathode of the second diode D2 is connected to a cathode of the first diode D1.
In the embodiment of the present invention, after two complementary PWM signals are inputted into the first signal input terminal and the fourth signal input terminal of the PWM signal modulation module 10, because the first signal input terminal is connected to the fourth driving signal input terminal of the isolation module 20, the second signal input terminal and the second logic output terminal are both connected to the first driving signal input terminal of the isolation module 20, the third signal input terminal and the first logic output terminal are both connected to the third driving signal input terminal of the isolation module 20, and the fourth signal input terminal is connected to the second driving signal input terminal of the isolation module 20; the first logic output end is a logic signal output by a first nor gate U3 through nor logic operation according to signals received by the first signal input end and the second signal input end; the second logic output end is a logic signal output by a second nor gate U4 through nor logic operation according to signals received by the third signal input end and the fourth signal input end, and finally two paths of PWM signals are converted into four paths of PWM driving signals, four driving signal output ends of the isolation module 20 respectively control four MOS switch tubes Q1, Q2, Q3 and Q4 of the full-bridge main circuit 30 to realize tube down modulation, that is, the duty ratio of an upper tube in the full-bridge main circuit 30 is always fixed to 50%, the falling edge of a lower tube is modulated according to the PWM rule, and the period of controlling the on-off of the four switch tubes of the full-bridge main circuit 30 by the tube down modulation is divided into positive and negative half cycles and is symmetrical.
When the first PWM signal is at a high level and the second PWM signal is at a low level, a digital signal "1" is input to a first input terminal of a first nor gate in the PWM signal modulation module 10, a digital signal "1" is input to a second input terminal of the first nor gate, and a digital signal "0" is output from a first logic output terminal; a first input end of the second NOR gate inputs a digital signal '0', a second input end of the second NOR gate inputs the digital signal '0', and a second logic output end outputs the digital signal '1'; according to the connection relationship between the four driving signal input ends of the isolation module 20 and the PWM signal modulation module 10, it is obtained that the logic high-side input end HIN of the first driving chip U1 of the isolation module 20 is "1", and the logic low-side input end LIN of the first driving chip U1 is "0"; a logic high-end input terminal HIN of a second driving chip U2 of the isolation module 20 is "0", a logic low-end input terminal LIN of a second driving chip U2 is "1", finally, a first driving signal output terminal of the isolation module 20 outputs a high level signal to control a first switching tube Q1 of the full-bridge main circuit 30 to be turned on, a second driving signal output terminal outputs a low level signal to control a fourth switching tube Q4 of the full-bridge main circuit 30 to be turned off, a third driving signal output terminal outputs a low level signal to control a second switching tube Q2 of the full-bridge main circuit 30 to be turned off, and a fourth driving signal output terminal outputs a high level signal to control a third switching tube Q3 of the full-bridge main circuit 30 to be turned on. Because the first switch tube Q1 and the third switch tube Q3 are conducted, the power input at the power input end of the full-bridge main circuit 30 passes through the first switch tube Q1, the resonant inductor L1 and the primary coil of the transformer 40 and then is output to the ground through the third switch tube Q3 to form a loop, at this time, positive half-cycle power transmission is performed, the power voltage is applied to the resonant inductor L1 and the primary side of the transformer 40, the primary side current of the transformer 40 is linearly increased from a higher peak value, the energy of the power grid is continuously converted into magnetic energy to be stored in the inductor coil and transmitted to the secondary side of the transformer 40, and the leakage inductance of the coil of the transformer 40 and the resonant inductor L1 stores.
When the control time sequence of the PWM signal controls the third switching tube Q3 to turn off, the first switching tube Q1 is still turned on, at this time, the leakage inductance of the resonant inductor L1 and the transformer 40 continues current through the MOS switching tube junction capacitors of the second switching tube Q2 and the third switching tube Q3, and at this time, positive half-cycle linear discharge occurs, the MOS switching tube junction capacitor of the second switching tube Q2 and the resonant inductor L1 are in series resonance, and since the primary side current of the transformer is large and the MOS junction capacitor is small, the charging and discharging process is rapid, the MOS switching tube junction capacitor of the second switching tube Q2 discharges, so that the parasitic diode of the second switching tube Q2 is turned on at zero voltage, and upper-layer switching clamping follow current is performed, the primary side voltage of the transformer is also reduced to zero, and the output current of the transformer 40 is reduced, so that ZVS turning on of the second switching tube Q2, that is turned.
Then, the first PWM signal changes to a low level, the second PWM signal changes to a high level, the first input terminal of the first nor gate in the PWM signal modulation module 10 inputs the digital signal "0", the second input terminal of the first nor gate inputs the digital signal "0", and the first logic output terminal outputs the digital signal "1"; a first input end of the second NOR gate inputs a digital signal '1', a second input end of the second NOR gate inputs the digital signal '1', and a second logic output end outputs the digital signal '0'; according to the connection relationship between the four driving signal input ends of the isolation module 20 and the PWM signal modulation module 10, it is obtained that the logic high-side input end HIN of the first driving chip U1 of the isolation module 20 is "0", and the logic low-side input end LIN of the first driving chip U1 is "1"; a logic high-end input terminal HIN of a second driving chip U2 of the isolation module 20 is "1", a logic low-end input terminal LIN of a second driving chip U2 is "0", finally, a first driving signal output terminal of the isolation module 20 outputs a high level signal to control a first switching tube Q1 of the full-bridge main circuit 30 to be turned off, a second driving signal output terminal outputs a low level signal to control a fourth switching tube Q4 of the full-bridge main circuit 30 to be turned on, a third driving signal output terminal outputs a low level signal to control a second switching tube Q2 of the full-bridge main circuit 30 to be turned on, and a fourth driving signal output terminal outputs a high level signal to control a third switching tube Q3 of the full-bridge main circuit 30 to be turned off. Because the fourth switching tube Q4 of the lower switching tube in the full-bridge main circuit 30 is modulated according to the PWM rule, and the control time sequence of the PWM signal controls the on-time of the fourth switching tube Q4 to be behind the on-time of the second switching tube Q2 of the upper switching tube, when the first switching tube Q1 is cut off, the second switching tube is turned on first, and the rest three switching tubes are still cut off; the positive half-cycle resonant discharge is realized by that the resonant inductor L1 and the leakage inductance of the transformer 40 follow current through the MOS switch tube junction capacitors of the first switch tube Q1 and the fourth switch tube Q4 to feed back energy to the power supply, the MOS switch tube junction capacitors of the fourth switch tube Q4 and the first switch tube Q1 are connected in parallel and then are connected in series with the resonant inductor L1 for resonance, and the MOS switch tube junction capacitor of the fourth switch tube Q4 discharges, because the leakage inductance applies back pressure to the power supply, the primary side current gradually drops to zero, and the ZVS on of the fourth switch tube Q4 is realized, namely the zero voltage on of the switch tube is switched on.
When the fourth switching tube Q4 is controlled to be switched on by the control timing sequence of the PWM signal, the fourth switching tube Q4 is switched on at zero voltage and zero current, at this time, the power input from the power input of the full-bridge main circuit 30 passes through the second switching tube Q2, the resonant inductor L1, and the primary coil of the transformer 40 and then is output to the ground through the fourth switching tube Q4 to form a loop, the primary side leakage inductance of the transformer 40 is excited at a constant voltage, and the primary side current rises in a reverse linear manner. Then, entering a negative half cycle to simultaneously realize ZVS for the first switching tube and the third switching tube. By controlling the time sequence of the four switching tubes of the full-bridge main circuit 30 and utilizing the resonance of the leakage inductance and the junction capacitance of the switching tubes on the full-bridge arm, the zero-voltage switching of the switching tubes is realized, the stress of the switching tubes is reduced, the switching loss of the switching tubes of the full-bridge main circuit is greatly reduced in the working process, and the switching frequency is improved.
As shown in fig. 4, the embodiment of the present invention further provides a full-bridge converter, including: a PWM generator 401, a dc power supply 402, and a full bridge control circuit 403;
the PWM generator 401 has a first PWM signal output terminal and a second PWM signal output terminal; the dc power supply 402 has a dc output;
a first PWM signal output end of the PWM generator 401 is connected to a first signal input end of the PWM signal modulation module 10, and a second PWM signal output end of the PWM generator 401 is connected to a fourth signal input end of the PWM signal modulation module 10; the dc output terminal of the dc power source 402 is connected to the power input terminal of the full-bridge main circuit 30. Preferably, the PWM generator is a UC3846 power supply PWM chip.
To sum up, the utility model discloses a full-bridge control circuit and full-bridge converter's beneficial effect lies in: by arranging the PWM signal modulation module, the PWM signal modulation module receives two paths of complementary PWM signals through the first signal input end and the fourth signal input end, and the first logic output end of the PWM signal modulation module realizes NOR logic output according to the signals received by the first signal input end and the second signal input end; the second logic output end of the PWM signal modulation module realizes NOR logic output according to signals received by the third signal input end and the fourth signal input end, and converts two paths of PWM driving signals into four paths of PWM driving; and four PWM drive signals are mapped one by one through four drive signal input ends of the isolation module and output to the four drive signal output ends, and the four drive signal output ends of the isolation module are mapped one by one with four controlled ends of the full-bridge main circuit, so that the four PWM drive signals modulate a lower tube of the full-bridge main circuit, the problem of large switching loss of the full-bridge converter controlled by a hard switch is solved, and the switching frequency of a switching tube of the full-bridge converter is improved. Through mutual cooperation among the PWM signal modulation module, the isolation module and the full-bridge main circuit, the low-tube modulation full-bridge main circuit is simply realized at low cost, the stress of a switch tube is reduced, and the working efficiency of the full-bridge converter is improved.
The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.
Claims (9)
1. A full bridge control circuit, comprising: the device comprises a PWM signal modulation module, an isolation module and a full-bridge main circuit; wherein,
the PWM signal modulation module is provided with a first signal input end, a second signal input end, a third signal input end, a fourth signal input end, a first logic output end and a second logic output end; the isolation module is provided with a first driving signal input end, a second driving signal input end, a third driving signal input end, a fourth driving signal input end and four driving signal output ends; the full-bridge main circuit is provided with a power input end, a power output end and four controlled ends, and each controlled end controls one switching tube of the full-bridge main circuit;
the first signal input terminal is used for receiving a first PWM signal, and the fourth signal input terminal is used for receiving a second PWM signal; the first PWM signal is complementary to the second PWM signal; the first signal input end is connected with the fourth driving signal input end, the second signal input end and the second logic output end are both connected with the first driving signal input end, the third signal input end and the first logic output end are both connected with the third driving signal input end, and the fourth signal input end is connected with the second driving signal input end; the first logic output end is used for realizing NOR logic output according to signals received by the first signal input end and the second signal input end; the second logic output end is used for realizing NOR logic output according to signals received by the third signal input end and the fourth signal input end;
the isolation module is used for mapping and outputting four signals received by the driving signal input end of the isolation module to the four driving signal output ends one by one; the four driving signal output ends are connected with the four controlled ends in a one-to-one mapping mode.
2. The full-bridge control circuit according to claim 1, wherein the PWM signal modulation module comprises a first nor gate and a second nor gate; wherein,
a first input end of the first nor gate is connected with a first signal input end of the PWM signal modulation module, a second input end of the first nor gate is connected with a second signal input end of the PWM signal modulation module, and an output end of the first nor gate is connected with a first logic output end of the PWM signal modulation module; the first input end of the second nor gate is connected with the third signal input end of the PWM signal modulation module, the second input end of the second nor gate is connected with the fourth signal input end of the PWM signal modulation module, and the output end of the second nor gate is connected with the second logic output end of the PWM signal modulation module.
3. The full-bridge control circuit according to claim 1, wherein the isolation module comprises a first driver chip and a second driver chip; the driving chip comprises a logic high-end input end HIN, a logic low-end input end LIN, a high-end output end Ho and a low-end output end Lo;
a logic high-end input end HIN of the first driving chip is connected with a first driving signal input end of the isolation module, a logic low-end input end LIN of the first driving chip is connected with a second driving signal input end of the isolation module, a high-end output end Ho of the first driving chip is connected with a first driving signal output end of the isolation module, and a low-end output end Lo of the first driving chip is connected with a second driving signal output end of the isolation module; a logic high-end input end HIN of the second driver chip is connected with a third driving signal input end of the isolation module, a logic low-end input end LIN of the second driver chip is connected with a fourth driving signal input end of the isolation module, a high-end output end Ho of the second driver chip is connected with a third driving signal output end of the isolation module, and a low-end output end Lo of the second driver chip is connected with a fourth driving signal output end of the isolation module.
4. The full-bridge control circuit according to claim 1, wherein the full-bridge main circuit comprises a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the power supply output end of the full-bridge main circuit is provided with a first power supply output end and a second power supply output end;
the control end of the first switching tube is connected with the first controlled end of the full-bridge main circuit, the input end of the first switching tube is connected with the power input end of the full-bridge main circuit, and the output end of the first switching tube is connected with the first power output end of the full-bridge main circuit; the control end of the second switching tube is connected with the second controlled end of the full-bridge main circuit, the input end of the second switching tube is connected with the input end of the first switching tube, and the output end of the second switching tube is connected with the second power supply output end of the full-bridge main circuit; the control end of the third switching tube is connected with the third controlled end of the full-bridge main circuit, the input end of the third switching tube is connected with the output end of the second switching tube, and the output end of the third switching tube is grounded; the control end of the fourth switch tube is connected with the fourth controlled end of the full-bridge main circuit, the input end of the fourth switch tube is connected with the output end of the first switch tube, and the output end of the fourth switch tube is grounded.
5. The full-bridge control circuit according to claim 4, wherein the full-bridge main circuit further comprises a first capacitor and a first inductor connected between the output terminal of the first switch tube and the first power output terminal of the full-bridge main circuit;
the first end of the first capacitor is connected with the input end of the first switch tube, and the second end of the first capacitor is grounded.
6. The full-bridge control circuit according to claim 4, wherein the switch tube is an N-channel MOS tube;
the control end of the switch tube is a grid electrode of the N-channel MOS tube, the input end of the switch tube is a drain electrode of the N-channel MOS tube, and the output end of the switch tube is a source electrode of the N-channel MOS tube.
7. The full-bridge control circuit according to claim 1, wherein the full-bridge main circuit further comprises a transformer;
the first end of the primary coil of the transformer is connected with the first power output end of the full-bridge main circuit, and the second end of the primary coil of the transformer is connected with the second power output end of the full-bridge main circuit.
8. The full-bridge control circuit of claim 7, wherein the transformer comprises a first secondary winding and a second secondary winding; the full-bridge main circuit also comprises a rectifying and filtering module, and the rectifying and filtering module is provided with an output end; the rectifying and filtering module comprises a first diode, a second inductor and a second capacitor;
the anode of the first diode is connected with the first end of the first secondary coil, and the cathode of the first diode is connected with the first end of the second inductor; the second end of the second inductor is connected with the output end; the second capacitor is connected with the second end of the second inductor, and the second end of the second capacitor is grounded; a second end of the first secondary coil is connected with a second end of the second capacitor; the first end of the second secondary coil is connected with the second end of the second capacitor, the second end of the second secondary coil is connected with the anode of the second diode, and the cathode of the second diode is connected with the cathode of the first diode.
9. A full-bridge converter is characterized by comprising a PWM generator, a direct current power supply and a full-bridge control circuit;
the full-bridge control circuit is the full-bridge control circuit of any one of claims 1 to 8;
the PWM generator has a first PWM signal output terminal and a second PWM signal output terminal; the direct current power supply is provided with a direct current output end;
a first PWM signal output end of the PWM generator is connected with a first signal input end of the PWM signal modulation module, and a second PWM signal output end of the PWM generator is connected with a fourth signal input end of the PWM signal modulation module; and the direct-current output end of the direct-current power supply is connected with the power supply input end of the full-bridge main circuit.
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| CN109742932A (en) * | 2019-03-13 | 2019-05-10 | 国家电网有限公司 | A kind of driving circuit and driver |
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