A converter control circuit and a conversion system

Abstract

The present invention relates to the technical field of power supplies, and mainly provides a converter control circuit and a conversion system. The circuit includes a sampling resistor, a driving module and a triggering module connected to the sampling resistor. The sampling resistor is used to output a sampling voltage according to the change of the inductor current in the converter; the triggering module is used to output a trigger signal to the controller at the moment when the sampling voltage is greater than a preset voltage, so that the controller controls the power tube in the converter to act; the driving module is used to control the freewheeling diode in the converter to turn on when the pulse signal is at the first level and the sampling voltage is greater than the preset voltage; and to control the freewheeling diode to turn off when the sampling voltage is less than the preset voltage or the pulse signal is at the second level. Based on this, the action time of the power tube and the freewheeling diode can be determined in real time according to the inductor current, so that the currents corresponding to the actions of the two tubes are consistent, and the action time of the two tubes is adjusted in real time according to the relationship between the load condition of the converter and the inductor current, thereby reducing the loss of the power tube.

Description

Technical Field

[0001] The present invention relates to the technical field of power supplies, and in particular, to a converter control circuit and a conversion system. Background Art

[0002] The Buck / Boost converter circuit topology has the advantages of simple structure, low cost, easy control, and high reliability, and is widely used in fields such as photovoltaic power generation, hybrid vehicles, and energy storage systems. Therefore, it has become the most commonly used topology structure for non-isolated DC / DC step-down converters. In engineering applications, in order to effectively reduce the switching loss and electromagnetic radiation interference of switching tubes while increasing the switching frequency, soft switching technology has emerged as the times require. In order to reduce the complexity of traditional soft switching technology, TCM control is mostly used to achieve the soft switching action of switching tubes. Among them, TCM control refers to using the inductor current to achieve the soft switching action of switching tubes.

[0003] However, the magnitude of the converter inductor current is determined by the load state of the converter, so that the time for the terminal voltage of the parasitic capacitance of the switching tube to resonate to zero is also different. In actual settings, the dead-time voltage of the switching tube is set according to the light load of the converter, resulting in that when the converter is under heavy load, the inductor current will resonate the terminal voltage of the parasitic capacitance of the switching tube to zero in a very short time, making the conduction time of the anti-parallel diode inside the switching tube longer. This operating state increases the conduction loss of the converter to a certain extent, thereby reducing the conversion efficiency of the converter. Moreover, due to the differences between devices, there is an error between the calculated dead time and the actual required dead time, resulting in the inductor current value when the converter freewheeling diode turns off being not equal to the inductor current value when the power tube turns on, thereby affecting the stability and safety of the converter. Summary of the Invention

[0004] Embodiments of the present invention provide a converter control circuit and a conversion system, mainly solving the technical problems of large switching loss, low conversion efficiency, and low stability of the converter in the prior art.

[0005] To solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: providing a converter control circuit, the converter control circuit includes a sampling resistor, a driving module, and a triggering module;

[0006] The sampling resistor is respectively connected to the driving module and the triggering module, the sampling resistor is further used to connect to a converter, the triggering module is further connected to a controller, the driving module is further used to connect to a freewheeling diode in the converter, and the driving module is further used to receive a pulse signal;

[0007] The sampling resistor responds to the change in the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current;

[0008] The trigger module is used to receive the sampling voltage and output a trigger signal to the controller at the moment when the sampling voltage is greater than a preset voltage, so that the controller controls the operation of the power tube in the converter according to the trigger signal;

[0009] The driving module is used to receive the sampling voltage, and when the pulse signal is at the first level, determine whether the sampling voltage is greater than the preset voltage, so as to output a turn-on signal to the freewheeling diode in the converter when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling diode in the converter to turn on according to the turn-on signal; and

[0010] When the sampling voltage is less than the preset voltage or the pulse signal is at the second level, output a turn-off signal to the converter, so that the freewheeling diode in the converter turns off according to the turn-off signal.

[0011] Optionally, when the trigger signal jumps from the first signal to the second signal, the trigger module includes a first comparison unit and a trigger unit;

[0012] The first comparison unit is connected to the trigger unit, the first comparison unit and the trigger unit are also both connected to the sampling resistor, and the trigger unit is also connected to the controller;

[0013] The first comparison unit is used to receive the sampling voltage and output a first control signal to the trigger unit when the sampling voltage is less than the preset voltage, so that the trigger unit outputs a first signal to the controller according to the first control signal; and

[0014] When the sampling voltage is greater than the preset voltage, output a second control signal to the trigger unit, so that the trigger unit outputs a second signal to the controller according to the second control signal, so that the controller controls the operation of the power tube in the converter.

[0015] Optionally, the first comparison unit includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10, and a capacitor C11;

[0016] The non-inverting input terminal of the comparator U2 is connected to the sampling resistor through the resistor R17, the non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10, the inverting input terminal of the comparator U2 is connected to the reference power supply through the resistor R15, the inverting input terminal of the comparator U2 is also grounded through the capacitor C11, and the output terminal of the comparator U2 is connected to the trigger unit.

[0017] Optionally, the triggering unit includes resistor R19, resistor R20, resistor R13, resistor R18, switching transistor Q5, comparator U3, capacitor C7, and capacitor C8;

[0018] The control terminal of the switching transistor Q5 is connected to the first comparison unit through the resistor R19, and the control terminal of the switching transistor Q5 is also grounded through the resistor R20. The first terminal of the switching transistor Q5 is connected to the non-inverting input terminal of the comparator U3. The non-inverting input terminal of the comparator U3 is also connected to the reference power supply through the resistor R13, and the non-inverting input terminal of the comparator U3 is also grounded through the capacitor C8. The inverting input terminal of the comparator U3 is connected to the sampling resistor through the resistor R18, and the inverting input terminal of the comparator U3 is also grounded through the capacitor C7. The output terminal of the comparator U3 is connected to the controller.

[0019] Optionally, the driving module includes a first control unit, a second comparison unit, and a second control unit;

[0020] The second comparison unit is respectively connected to the first control unit and the second control unit. The second comparison unit is also connected to the sampling resistor. The second control unit is also connected to the freewheeling diode in the converter. The first control unit is also used to receive the pulse signal;

[0021] The first control unit is used to control the second comparison unit to judge whether the sampling voltage is greater than the preset voltage when the pulse signal is at the first level, so that when the sampling voltage is greater than the preset voltage, the second comparison unit outputs a first driving signal to the second control unit; when the sampling voltage is less than the preset voltage, the second comparison unit outputs a second driving signal to the second control unit; and

[0022] When the pulse signal is at the second level, control the second comparison unit to output a second driving signal to the second control unit;

[0023] The second control unit is used to output a turn-on signal to the freewheeling diode in the converter when receiving the first driving signal, so that the freewheeling diode in the converter is turned on according to the turn-on signal; and

[0024] When receiving the second driving signal, output a turn-off signal to the converter, so that the freewheeling diode in the converter is turned off according to the turn-off signal.

[0025] Optionally, the second comparison unit includes comparator U4, resistor R23, and capacitor C14;

[0026] The non-inverting input terminal of the comparator U4 is respectively connected to the sampling resistor and the first control unit. The inverting input terminal of the comparator U4 is connected to the reference power supply through the resistor R23. The inverting input terminal of the comparator U4 is also grounded through the capacitor C14. The output terminal of the comparator U4 is connected to the second control unit.

[0027] Optionally, the driving module further includes a delay unit;

[0028] The delay unit is respectively connected to the sampling resistor and the second comparison unit;

[0029] The delay unit is configured to obtain the sampling voltage and input the sampling voltage to the second comparison unit after delaying the corresponding time based on the magnitude of the sampling voltage.

[0030] Optionally, the second control unit includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switching transistor Q7, a switching transistor Q8, a switching transistor Q9, and a switching transistor Q10;

[0031] The control terminal of the switching transistor Q7 is connected to the second comparison unit. The first terminal of the switching transistor Q7 is connected to the control terminal of the switching transistor Q8 through the resistor R30. The control terminal of the switching transistor Q8 is also connected to the first power supply through the resistor R29. The second terminal of the switching transistor Q8 is respectively connected to the control terminals of the switching transistor Q9 and the switching transistor Q10 through the resistor R31. The control terminal of the switching transistor Q10 is also grounded through the resistor R32. The first terminal of the switching transistor Q8 and the first terminal of the switching transistor Q9 are both connected to the first power supply. The second terminal of the switching transistor Q9 and the first terminal of the switching transistor Q10 are also both connected to the freewheeling diode in the converter.

[0032] Optionally, the converter control circuit further includes an amplification module;

[0033] The amplification module is respectively connected to the sampling resistor, the triggering module, and the driving module;

[0034] The amplification module is configured to receive the sampling voltage output by the sampling resistor and amplify the sampling voltage and then output it to the triggering module and the driving module.

[0035] To solve the above technical problems, another technical solution adopted in the embodiments of the present invention is: to provide a conversion system, the conversion system includes:

[0036] A converter;

[0037] A controller; and

[0038] The converter control circuit as described above.

[0039] Differing from the related art, the present invention provides a converter control circuit and a conversion system. The circuit includes a sampling resistor, a driving module, and a triggering module; the sampling resistor is respectively connected to the driving module and the triggering module, the sampling resistor is further used to connect to a converter, the triggering module is further connected to a controller, the driving module is further used to connect to a freewheeling diode in the converter, and the driving module is further used to receive a pulse signal; the sampling resistor responds to a change in the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current; the triggering module is used to receive the sampling voltage and output a trigger signal to the controller at the moment when the sampling voltage is greater than a preset voltage, so that the controller controls the operation of a power transistor in the converter according to the trigger signal; the driving module is used to receive the sampling voltage and, when the pulse signal is at a first level, determine whether the sampling voltage is greater than the preset voltage, so as to output an on signal to the freewheeling diode in the converter when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling diode in the converter to turn on according to the on signal; and when the sampling voltage is less than the preset voltage or the pulse signal is at a second level, output an off signal to the converter, so that the freewheeling diode in the converter turns off according to the off signal. Based on this, the operation times of the power transistor and the freewheeling diode can be determined in real time according to the inductor current, so that the currents corresponding to the operations of the freewheeling diode and the power transistor are consistent, thereby improving the stability and safety of the converter; and the operation times of the power transistor and the freewheeling diode are adjusted in real time according to the relationship between the load condition of the converter and the inductor current, thereby reducing the loss of the power transistor and improving the conversion efficiency of the converter. Description of the Drawings

[0040] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the figures in the drawings do not constitute a proportional limitation.

[0041] Figure 1 is a structural block diagram of a conversion system provided by an embodiment of the present invention;

[0042] Figure 2a is a circuit diagram of a Buck converter provided by an embodiment of the present invention;

[0043] Figure 2b is a circuit diagram of a Boost converter provided by an embodiment of the present invention;

[0044] Figure 3 is a waveform diagram of the operation of a converter provided by an embodiment of the present invention;

[0045] Figure 4 It is a structural block diagram of a converter control circuit provided by an embodiment of the present invention;

[0046] Figure 5 It is a circuit diagram of a converter control circuit provided by an embodiment of the present invention. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] It should be noted that if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different module division from that in the device schematic diagram or a different order from that in the flowchart.

[0049] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific implementation manners and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0050] Please refer to Figure 1 , Figure 1 It is a structural block diagram of a conversion system provided by an embodiment of the present invention. As shown in Figure 1 , the conversion system 100 includes a converter 10, a controller 20 and a converter control circuit 30; the converter control circuit 30 is respectively connected to the converter 10 and the controller 20. The converter control circuit 30 is used to detect the output current of the converter 10, and output a corresponding trigger signal to the controller 20 based on the change of the output current, so that the controller 20 controls the on and off of the switching tubes in the converter 10 based on the trigger signal. Among them, the converter 10 can be a Buck converter or a Boost converter.

[0051] Further, taking the Buck converter as an example, please refer to Figure 2a , Figure 2a It is a circuit diagram of a Buck converter provided by an embodiment of the present invention. As shown in Figure 2aAs shown, the converter 10 includes a switching transistor Q1 (power transistor), a switching transistor Q2 (freewheeling diode), a resonant inductor Lr, and a capacitor C2. The switching transistor Q1 and the switching transistor Q2 are connected in series with each other. The second end of the switching transistor Q1 is also connected to the capacitor C2 through the resonant inductor Lr. The control ends of the switching transistor Q1 and the switching transistor Q2 are both connected to the controller 20.

[0052] It should be noted that during the operation of the converter 10, the controller 20 is mainly used to control the on and off of the switching transistor Q1 and the switching transistor Q2 to change the input voltage (DC-IN+) of the converter 10, so as to output the target voltage. Both the switching transistor Q1 and the switching transistor Q2 include parasitic capacitors. During the on and off process of the switching transistor Q1 and the switching transistor Q2, the parasitic capacitors will store voltage, which will cause relatively large losses when the switching transistor Q1 and the switching transistor Q2 are turned off or on. Therefore, when realizing voltage conversion through switching transistors, it is necessary to ensure that the switching transistor Q1 and the switching transistor Q2 are in the soft-switching state to reduce the losses of the switching transistors, thereby improving the service life of the converter 10.

[0053] Specifically, in combination with Figure 2a and Figure 3 , when there is an input voltage and the switching transistor Q1 is in the off state and the switching transistor Q2 is in the on state, the inductor current on the resonant inductor Lr will flow through the switching transistor Q2 into the ground terminal. At this time, the inductor current will decrease in the positive direction (that is, the inductor current continuously decreases). When the inductor current on the resonant inductor Lr decreases to 0, the capacitor C2 will charge the resonant inductor Lr in the reverse direction, so that the inductor current increases in the reverse direction (that is, the inductor current continues to decrease). When the inductor current increases in the reverse direction to a preset value (I n-set ), the switching transistor Q2 will turn off. Since the inductor current starts to charge the parasitic capacitor of the switching transistor Q2 only after the switching transistor Q2 is turned off, the voltage stored in the parasitic capacitor when the switching transistor Q2 operates is 0, thus realizing the soft turn-off of the switching transistor Q2.

[0054] After the switching transistor Q2 is turned off, the resonant inductor Lr resonates with the parasitic capacitors of the switching transistor Q1 and the switching transistor Q2, so that the inductor current i Lr (t) of the resonant inductor Lr continues to increase in the reverse direction, the voltage u C2 (t) of the parasitic capacitor of the switching transistor Q2 starts to increase in the positive direction, and the voltage u C1 (t) of the parasitic capacitor of the switching transistor Q1 decreases in the positive direction. During the resonance process, the voltage on the parasitic capacitor of the switching transistor Q2 increases in the positive direction to the maximum value (V pm), the voltage across the parasitic capacitance of the switching transistor Q1 also drops to the minimum value (-V F ). When the voltage stored in the parasitic capacitance of the switching transistor Q2 increases in the positive direction to the maximum value, the parasitic capacitance of the switching transistor Q2 starts to discharge the resonant inductor Lr, causing the inductor current in the resonant inductor Lr to start decreasing in the reverse direction (i.e., the inductor current is slowly increasing). Among them, when the voltage stored in the parasitic capacitance of the switching transistor Q1 decreases to a certain value, the switching transistor Q1 conducts, thus achieving soft turn-on of the switching transistor Q1.

[0055] After the switching transistor Q1 is turned on, the input voltage charges the resonant inductor Lr through the switching transistor Q1. At this time, the inductor current in the resonant inductor Lr continues to decrease in the reverse direction. When the inductor current decreases to 0, the inductor current starts to increase in the positive direction until it increases to the maximum value I pm . At this time, the switching transistor Q1 is turned off. Since the voltage stored in the parasitic capacitance of the switching transistor Q1 is 0, the switching transistor Q1 achieves soft turn-off.

[0056] After the switching transistor Q1 is turned off, the resonant inductor Lr starts to resonate with the parasitic capacitance of the switching transistor Q1 and the parasitic capacitance of the switching transistor Q2, causing the voltage stored in the parasitic capacitance of the switching transistor Q1 to continuously increase, while the voltage stored in the parasitic capacitance of the switching transistor Q2 continuously decreases, and the inductor current also continuously decreases. When the voltage stored in the parasitic capacitance of the switching transistor Q2 is 0, the switching transistor Q2 conducts, thus achieving soft turn-on of the switching transistor Q2.

[0057] Based on this, it can be known that during the operation of the switching transistors Q1 and Q2, the inductor current is closely related to the voltages stored in the parasitic capacitances of the switching transistors Q1 and Q2. Therefore, by monitoring the inductor current of the resonant inductor Lr, soft switching of the switching transistors can be achieved.

[0058] In another embodiment, when the converter 10 is a Boost converter, as Figure 2b shown, this Boost converter includes a switching transistor Q3 (freewheeling diode), a switching transistor Q4 (power transistor), a resonant inductor Lm, and a capacitor C4. The switching transistors Q3 and Q4 are connected in series. The second terminal of the switching transistor Q3 also receives the input voltage through the resonant inductor Lm. The capacitor C4 is connected to the first terminal of the switching transistor Q3 and the second terminal of the switching transistor Q4 respectively. The control terminals of the switching transistor Q3 and the switching transistor Q4 are also both connected to the controller 20. Among them, the operating principle of the Boost converter is similar to that of the Buck converter, and will not be elaborated here.

[0059] In some embodiments, please refer toFigure 4 , Figure 4 is a structural block diagram of a converter control circuit provided by an embodiment of the present invention. As Figure 4 shown, the converter control circuit 30 includes a sampling resistor R5, a driving module 31, and a triggering module 32;

[0060] The sampling resistor R5 is respectively connected to the driving module 31 and the triggering module 32. The sampling resistor R5 is also used to connect to the converter 10. The triggering module 32 is also connected to the controller 20. The driving module 31 is also used to connect to the freewheeling diode in the converter 10. The driving module 31 is also used to receive a pulse signal;

[0061] The sampling resistor R5 responds to the change in the inductor current in the converter 10 and outputs a corresponding sampling voltage based on the changed inductor current;

[0062] The triggering module 32 is used to receive the sampling voltage and output a trigger signal to the controller 20 at the moment when the sampling voltage is greater than a preset voltage, so that the controller 20 controls the operation of the power tube in the converter 10 according to the trigger signal;

[0063] The driving module 31 is used to receive the sampling voltage and, when the pulse signal is at a first level, determine whether the sampling voltage is greater than the preset voltage, so as to output an on signal to the freewheeling diode in the converter 10 when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling diode in the converter 10 to turn on according to the on signal; and

[0064] when the sampling voltage is less than the preset voltage or the pulse signal is at a second level, output an off signal to the converter 10, so that the freewheeling diode in the converter 10 turns off according to the off signal.

[0065] It can be known that the converter control circuit 30 mainly uses the sampling resistor R5 to detect the inductor current in the converter 10 in real time, and determines the on and off times of the switching transistor Q1 and the switching transistor Q2 based on the inductor current, so as to realize the soft switching of the switching transistor Q1 and the switching transistor Q2.

[0066] Specifically, when the sampling resistor R5 detects the inductor current, it outputs a corresponding sampling voltage to the driving module 31 and the triggering module 32 based on the inductor current. Meanwhile, the driving module 31 also receives the pulse signal. At this time, if the pulse signal is at the first level, the driving module 31 will receive the sampling voltage and determine whether the sampling voltage is greater than the preset voltage. If the sampling voltage is greater than the preset voltage, the driving module 31 will output a turn-on signal to the freewheeling diode (switching transistor Q2) in the converter 10, so that the switching transistor Q2 conducts based on the turn-on signal; and if the sampling voltage is less than the preset voltage, the driving module 31 will output a turn-off signal to the switching transistor Q2 to control the switching transistor Q2 to turn off. Among them, when the pulse signal is at the second level, at this time, regardless of whether the pulse signal is greater than the preset voltage, the driving module 31 will output a turn-off signal to the switching transistor Q2, so that the switching transistor Q2 maintains the off state.

[0067] It should be noted that, as Figure 3 shown, the level state of the pulse signal (PWM-GH) is determined according to the working state of the switching transistor Q1. When the switching transistor Q1 is in the off state, the pulse signal is at the first level; and when the switching transistor Q1 is in the on state, the pulse signal is at the second level.

[0068] When the triggering module 32 receives the sampling voltage, it will output a trigger signal to the controller 20 at the moment when the sampling voltage is greater than the preset voltage, and after receiving the trigger signal, the controller 20 will control the switching transistor Q1 to act according to the trigger signal. Among them, the preset voltage is set according to the preset value (I n-set ) of the inductor current, that is, when the collected inductor current is greater than the preset value, it is considered that the sampling voltage is greater than the preset voltage, and vice versa.

[0069] In some embodiments, when the controller 20 controls the switching transistor Q1 to act, it can control the switching transistor Q1 to act according to the trigger signal, or directly control the switching transistor Q1 to act. And if the controller 20 controls the switching transistor Q1 to turn on according to the trigger signal, then the controller 20 will continuously monitor the inductor current of the resonant inductor Lr and directly control the switching transistor Q1 to turn off after the inductor current meets the conditions; and if the controller 20 controls the switching transistor Q1 to turn off according to the trigger signal, then it will directly control the switching transistor Q1 to turn on after the inductor current meets the conditions. For example, when the switching transistor Q1 turns on based on the trigger signal, the inductor current of the resonant inductor Lr will increase linearly, as Figure 3as shown, and when the inductor current increases to the peak current (I pm ) of the inductor current, the controller 20 controls the switching transistor Q1 to turn off.

[0070] In another embodiment, the trigger signal is the moment when the first signal jumps to the second signal, and the trigger module 32 includes a first comparison unit 321 and a trigger unit 322;

[0071] The first comparison unit 321 is connected to the trigger unit 322. The first comparison unit 321 and the trigger unit 322 are also both connected to the sampling resistor R5, and the trigger unit 322 is also connected to the controller 20;

[0072] The first comparison unit 321 is configured to receive the sampling voltage, and when the sampling voltage is less than the preset voltage, output a first control signal to the trigger unit 322, so that the trigger unit 322 outputs a first signal to the controller 20 according to the first control signal; and

[0073] When the sampling voltage is greater than the preset voltage, output a second control signal to the trigger unit 322, so that the trigger unit 322 outputs a second signal to the controller 20 according to the second control signal, so that the controller 20 controls the power transistor in the converter 10 to act.

[0074] It can be known that the inductor current on the resonant inductor Lr changes in real time with the on and off of the switching transistor Q1 and the switching transistor Q2. Therefore, when the converter 10 works, the sampling voltage output by the sampling resistor R5 also changes in real time.

[0075] After the sampling resistor R5 outputs a sampling voltage to the trigger module 32, the first comparison unit 321 compares the magnitude of the sampling voltage with the preset voltage, and when the sampling voltage is less than the preset voltage, outputs a first control signal to the trigger unit 322; if the sampling voltage is greater than the preset voltage, the first comparison unit 321 outputs a second control signal to the trigger unit 322. When the trigger unit 322 receives the first control signal, it compares the sampling voltage with the preset voltage according to the first control signal. At this time, since the sampling voltage is less than the preset voltage, the trigger unit 322 outputs a first signal to the controller 20 according to the first control signal. Among them, since the switching transistor Q1 only operates at the moment when it receives a trigger signal (the first signal jumps to the second signal), the controller 20 does not control the switching transistor Q1 to operate at this time. When the trigger unit 322 receives the second control signal, the trigger unit 322 outputs a second signal to the controller 20 based on the second control signal. The controller 20 outputs a trigger signal to the switching transistor Q1 at the moment when it receives the second signal, thereby controlling the switching transistor Q1 to operate.

[0076] It should be noted that in this embodiment, the controller 20 is set to trigger on the falling edge, that is, when the controller 20 receives a falling edge signal, it controls the switching transistor Q1 to operate. Based on this, the first signal is a high-level signal, and the second signal is a low-level signal. Optionally, in other embodiments, the controller 20 can also be triggered on the rising edge, that is, when the controller 20 receives a signal that jumps from a low level to a high level, it controls the switching transistor Q1 to operate.

[0077] Further, in some embodiments, please refer to Figure 5 , Figure 5 is a circuit diagram of a converter control circuit provided by an embodiment of the present invention. As Figure 5 shown, the first comparison unit 321 includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10, and a capacitor C11; the trigger unit 322 includes a resistor R19, a resistor R20, a resistor R13, a resistor R18, a switching transistor Q5, a comparator U3, a capacitor C7, and a capacitor C8.

[0078] The non-inverting input terminal of the comparator U2 is connected to the sampling resistor R5 through the resistor R17. The non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10. The inverting input terminal of the comparator U2 is connected to the reference power supply (V RF2is connected, and the inverting input terminal of the comparator U2 is also grounded through the capacitor C11. The output terminal of the comparator U2 is connected to the trigger unit 322.

[0079] The control terminal of the switching transistor Q5 is connected to the first comparison unit 321 through the resistor R19. The control terminal of the switching transistor Q5 is also grounded through the resistor R20. The first terminal of the switching transistor Q5 is connected to the non-inverting input terminal of the comparator U3. The non-inverting input terminal of the comparator U3 is also connected to the reference power supply (V RF2 ) through the resistor R13. The non-inverting input terminal of the comparator U3 is also grounded through the capacitor C8. The inverting input terminal of the comparator U3 is connected to the sampling resistor R5 through the resistor R18. The inverting input terminal of the comparator U3 is also grounded through the capacitor C7. The output terminal of the comparator U3 is connected to the controller 20.

[0080] Specifically, when the sampling resistor R5 outputs a sampling voltage, the non-inverting input terminal of the comparator U2 will receive the sampling voltage through the resistor R17 and compare the sampling voltage with the preset voltage corresponding to the reference power supply. At this time, if the sampling voltage is less than the preset voltage, the comparator U2 will output a first control signal (low-level signal). When the comparator U2 outputs the first control signal, the switching transistor Q5 will turn off based on the first control signal. At this time, the voltage at the non-inverting input terminal of the comparator U3 is the preset voltage. At the same time, the inverting input terminal of the comparator U3 will receive the sampling voltage through the resistor R18. Since the sampling voltage is less than the preset voltage at this time, the comparator U3 will output a first signal (high-level signal) to the controller 20.

[0081] When the sampling voltage is greater than the preset voltage, the comparator U2 will output a second control signal, and the switching transistor Q5 will turn on based on the second control signal, thereby pulling down the voltage at the non-inverting input terminal of the comparator U3, causing the comparator U3 to output a second signal (low-level signal) to the controller 20. When the controller 20 receives the second signal instantaneously, it is considered that the controller 20 receives the trigger signal (GH-ON), and thus controls the switching transistor Q1 to act according to the trigger signal, thereby realizing the soft switching of the switching transistor Q1.

[0082] In another embodiment, as Figure 4 shown, the driving module 31 includes a first control unit 311, a second comparison unit 312, and a second control unit 313;

[0083] The second comparison unit 312 is respectively connected to the first control unit 311 and the second control unit 313. The second comparison unit 312 is also connected to the sampling resistor R5. The second control unit 313 is also connected to the freewheeling diode in the converter 10. The first control unit 311 is further configured to receive the pulse signal;

[0084] The first control unit 311 is configured to, when the pulse signal is at a first level, control the second comparison unit 312 to determine whether the sampled voltage is greater than a preset voltage, so that when the sampled voltage is greater than the preset voltage, the second comparison unit 312 outputs a first drive signal to the second control unit 313; when the sampled voltage is less than the preset voltage, the second comparison unit 312 outputs a second drive signal to the second control unit 313; and

[0085] when the pulse signal is at a second level, control the second comparison unit 312 to output a second drive signal to the second control unit 313;

[0086] The second control unit 313 is configured to output a turn-on signal to the freewheeling diode in the converter 10 when receiving the first drive signal, so that the freewheeling diode in the converter 10 is turned on according to the turn-on signal; and

[0087] output a turn-off signal to the converter 10 when receiving the second drive signal, so that the freewheeling diode in the converter 10 is turned off according to the turn-off signal.

[0088] Specifically, when the sampling resistor R5 outputs a sampled voltage to the drive module 31, the first control unit 311 receives the pulse signal, and when the pulse signal is at a first level, transmits the sampled voltage to the second comparison unit 312, so that the second comparison unit 312 determines the magnitude relationship between the sampled voltage and the preset voltage. When the sampled voltage is greater than the preset voltage, a first drive signal is output to the second control unit 313; if the sampled voltage is less than the preset voltage, a second drive signal is output to the second control unit 313. Among them, if the pulse signal is at a second level, the first control unit 311 controls the second comparison unit 312 to directly output a second drive signal to the second control unit 313. When the second control unit 313 receives the first drive signal, an on signal is output to the freewheeling diode in the converter 10 based on the first drive signal to control the freewheeling diode to turn on; if the second control unit 313 receives the second drive signal, the freewheeling diode is controlled to close according to the second drive signal.

[0089] In another embodiment, please refer to Figure 5, the first control unit 311 includes a resistor R25, a resistor R26, and a switching transistor Q6; the second comparison unit 312 includes a comparator U4, a resistor R23, and a capacitor C14; the second control unit 313 includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switching transistor Q7, a switching transistor Q8, a switching transistor Q9, and a switching transistor Q10.

[0090] The control terminal of the switching transistor Q6 receives the pulse signal through the resistor R25, the control terminal of the switching transistor Q6 is also grounded through the resistor R26, the first terminal of the switching transistor Q6 is respectively connected to the sampling resistor R5 and the second comparison unit 312, and the second terminal of the switching transistor Q6 is used for grounding.

[0091] The non-inverting input terminal of the comparator U4 is respectively connected to the sampling resistor R5 and the first control unit 311, the inverting input terminal of the comparator U4 is connected to a reference power supply (V RF2 ) through the resistor R23, the inverting input terminal of the comparator U4 is also grounded through the capacitor C14, and the output terminal of the comparator U4 is connected to the second control unit 313.

[0092] The control terminal of the switching transistor Q7 is connected to the second comparison unit 312, the first terminal of the switching transistor Q7 is connected to the control terminal of the switching transistor Q8 through the resistor R30, the control terminal of the switching transistor Q8 is also connected to a first power supply (12V) through the resistor R29, the second terminal of the switching transistor Q8 is connected to the control terminals of the switching transistor Q9 and the switching transistor Q10 respectively through the resistor R31, the control terminal of the switching transistor Q10 is also grounded through the resistor R32, the first terminal of the switching transistor Q8 and the first terminal of the switching transistor Q9 are both connected to the first power supply, and the second terminal of the switching transistor Q9 and the first terminal of the switching transistor Q10 are also both connected to the freewheeling diode in the converter 10.

[0093] Among them, as Figure 5 can be seen, the switching transistors Q7 and Q9 are N-channel switching transistors, and the switching transistors Q8 and Q10 are P-channel switching transistors.

[0094] Specifically, when the pulse signal is at the first level (low-level signal), the switching transistor Q6 is in the cut-off state. At this time, the sampling voltage is directly output to the non-inverting input terminal of the comparator U4, and the comparator U4 compares the sampling voltage with the preset voltage corresponding to the reference power supply. If the sampling voltage is greater than the preset voltage, the comparator U4 outputs a first driving signal (high-level signal) to the switching transistor Q7 to turn on the switching transistor Q7. After the switching transistor Q7 is turned on, the switching transistors Q8 and Q9 are also turned on, thereby outputting a turn-on signal (high level) to the switching transistor Q2, and further controlling the soft turn-on of the switching transistor Q2.

[0095] If the sampling voltage is less than the preset voltage, the comparator U4 outputs a second driving signal (low-level signal). After receiving the low-level signal, the switching transistor Q7 is turned off, so that the switching transistors Q8 and Q9 are also turned off. When the switching transistor Q9 is turned off, the switching transistor Q10 is turned on, thereby outputting a turn-off signal (low level) to the switching transistor Q2, and further controlling the soft turn-off of the switching transistor Q2.

[0096] When the pulse signal is at the second level (high-level signal), the switching transistor Q6 is turned on, so that the voltage at the non-inverting input terminal of the comparator U4 is directly pulled down. At this time, the sampling voltage is discharged through the switching transistor Q6, and the comparator U4 directly outputs a second driving signal, so that the switching transistor Q2 is turned off.

[0097] In some embodiments, as Figure 5 shown, the second control unit 313 further includes a resistor R33, a resistor R34, and a diode D1; the resistor R33 is connected in series with the diode D1, and the series-connected resistor R33 and diode D1 are also connected in parallel with the resistor R34. The resistor R34 is also respectively connected to the second terminal of the switching transistor Q9 and the freewheeling diode in the converter 10.

[0098] Specifically, after the switching transistors Q7, Q8, and Q9 are turned on, the voltage of the first power supply forms a turn-on signal through the switching transistor Q9 and the resistor R34 and acts on the freewheeling diode to control the turn-on of the freewheeling diode. When the switching transistor Q10 is turned on, the driving voltage on the freewheeling diode is reversely input to the second control unit 313. At this time, the diode D1 is turned on, and the driving voltage is quickly discharged through the resistor R33, the resistor R34, and the switching transistor Q10, so that the freewheeling diode in the converter 10 is quickly turned off.

[0099] It should be noted that when the converter 10 is in a heavy load state, the peak value of the inductor current is very large when the power tube in the converter 10 is turned off, so that the voltage at the parasitic capacitance end of the switching tube in the converter 10 resonates to zero quickly; while if the converter 10 is in a light load state, the peak value of the inductor current of the resonant inductor Lr is very small, so that the time for the parasitic capacitance to resonate to zero is relatively long. Therefore, during the operation of the converter 10, it is necessary to adjust the action time of the real-time switching tube Q1 and the switching tube Q2 according to the inductor current, so that the switching tube Q1 or the switching tube Q2 operates in soft switching. Based on this, the present application introduces a delay unit 314 to determine the action time of the switching tube Q2 based on the delay unit 314 and the inductor current, thereby reducing the loss of the converter 10.

[0100] Further, in another embodiment, as Figure 4 shown, the driving module 31 further includes a delay unit 314, and the delay unit 314 is respectively connected to the sampling resistor R5 and the second comparison unit 312;

[0101] The delay unit 314 is configured to obtain the sampling voltage and input the sampling voltage to the second comparison unit 312 after delaying the corresponding time based on the magnitude of the sampling voltage.

[0102] Specifically, when the sampling resistor R5 outputs a sampling voltage, the delay unit 314 will receive the sampling voltage and input the sampling voltage to the second comparison unit 312 after delaying the preset time based on the magnitude of the sampling voltage, so that the second comparison unit 312 can judge the magnitude of the sampling voltage and the preset voltage. It should be noted that due to the influence of the load condition on the inductor current, the magnitude of the inductor current is not the same at the same moment of the converter 10, thus affecting the delay time of the delay unit 314. Therefore, the delay time of the delay unit 314 is determined by the magnitude of the sampling voltage corresponding to the inductor current, and further, the soft switching of the switching tube in the converter 10 can be ensured.

[0103] In some embodiments, as Figure 5 shown, the delay unit 314 includes a resistor R24 and a capacitor C13; the resistor R24 is respectively connected to the sampling resistor R5 and the capacitor C13, the first end of the capacitor C13 is connected to the second comparison unit 312, and the second end of the capacitor C13 is grounded.

[0104] After the sampling resistor R5 outputs the sampling voltage, the capacitor C13 receives the sampling voltage through the resistor R24 and starts charging based on the sampling voltage; after the capacitor C13 is charged for a corresponding time, it inputs the sampling voltage to the second comparison unit 312. Since the capacitance of the capacitor C13 is fixed, the larger the sampling voltage, the faster the capacitor C13 charges, and the faster the second comparison unit 312 receives the sampling voltage.

[0105] In some embodiments, as Figure 4 shown, the converter control circuit 30 further includes an amplification module 33; the amplification module 33 is respectively connected to the sampling resistor R5, the trigger module 32, and the driving module 31;

[0106] The amplification module 33 is configured to receive the sampling voltage output by the sampling resistor R5, amplify the sampling voltage, and output it to the trigger module 32 and the driving module 31.

[0107] Specifically, after the sampling resistor R5 outputs the sampling voltage based on the inductor current, the sampling voltage is input to the amplification module 33, so that the amplification module 33 amplifies the sampling voltage and inputs the amplified sampling voltage to the driving module 31 and the trigger module 32. It should be noted that since the resistance value of the sampling resistor R5 is small, when the inductor current flows through the sampling resistor R5, the voltage drop across the sampling resistor R5 is also small. Therefore, in order to accurately obtain the current change of the resonant inductor Lr, the amplification module 33 is introduced to amplify the sampling voltage through the amplification module 33, thereby improving the switching accuracy of the converter 10.

[0108] In some embodiments, as Figure 5 shown, the amplification module 33 includes a differential amplifier U1 and a resistor R10;

[0109] Two input terminals of the differential amplifier U1 are respectively connected to both ends of the sampling resistor R5, and the non-inverting input terminal of the differential amplifier U1 is further configured to be connected to a first power supply V RF1 , the output terminal of the differential amplifier U1 is respectively connected to the driving module 31 and the trigger module 32, and the resistor R10 is respectively connected to the output terminal of the differential amplifier U1 and the inverting input terminal of the differential amplifier U1.

[0110] Among them, the differential amplifier refers to a device that amplifies the difference between two input signals. Therefore, when a current flows through the sampling resistor R5, a corresponding sampling voltage will also be generated on the sampling resistor R5. At this time, the differential amplifier U1 will obtain the voltage drop (sampling voltage) on the sampling resistor R5 and amplify the voltage drop, and finally input the amplified sampling voltage to the driving module 31 and the triggering module 32.

[0111] An embodiment of the present invention provides a converter control circuit, which includes a sampling resistor, a driving module, and a triggering module; the sampling resistor is respectively connected to the driving module and the triggering module, and the sampling resistor is also used to connect to a converter. The triggering module is also connected to a controller, and the driving module is also used to connect to a freewheeling diode in the converter. The driving module is also used to receive a pulse signal; the sampling resistor responds to the change in the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current; the triggering module is used to receive the sampling voltage and output a trigger signal to the controller at the moment when the sampling voltage is greater than a preset voltage, so that the controller controls the operation of a power transistor in the converter according to the trigger signal; the driving module is used to receive the sampling voltage and, when the pulse signal is at a first level, determine whether the sampling voltage is greater than the preset voltage, so as to output a turn-on signal to the freewheeling diode in the converter when the sampling voltage is greater than the preset voltage, thereby controlling the freewheeling diode in the converter to turn on according to the turn-on signal; and when the sampling voltage is less than the preset voltage or the pulse signal is at a second level, output a turn-off signal to the converter, so that the freewheeling diode in the converter turns off according to the turn-off signal. Based on this, the operation time of the power transistor and the freewheeling diode can be determined in real time according to the inductor current, so that the currents corresponding to the operations of the freewheeling diode and the power transistor are the same, thereby improving the stability and safety of the converter; and the operation time of the power transistor and the freewheeling diode is adjusted in real time according to the relationship between the load condition of the converter and the inductor current, thereby reducing the loss of the power transistor and improving the conversion efficiency of the converter.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A converter control circuit, characterized in that: The converter control circuit includes a sampling resistor, a driving module and a trigger module; The sampling resistor is connected to the driving module and the triggering module respectively, the sampling resistor is also used to connect the converter, the triggering module is also connected to the controller, the driving module is also used to connect the freewheeling tube in the converter, and the driving module is also used to receive the pulse signal; The sampling resistor responds to the change of the inductor current in the converter and outputs a corresponding sampling voltage based on the changed inductor current; The trigger module is used to receive the sampled voltage and output a trigger signal to the controller at the moment when the sampled voltage is greater than a preset voltage, so that the controller controls the action of the power tube in the converter according to the trigger signal; The driving module is used to receive the sampled voltage, and when the pulse signal is at a first level, determine whether the sampled voltage is greater than the preset voltage, so as to output an opening signal to the freewheeling tube in the converter when the sampled voltage is greater than the preset voltage, thereby controlling the freewheeling tube in the converter to be opened according to the opening signal; as well as When the sampling voltage is less than the preset voltage or the pulse signal is at the second level, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is shut down according to the shutdown signal.

2. The converter control circuit according to claim 1, characterized in that: The trigger signal is the moment when the first signal jumps to the second signal, and the trigger module includes a first comparison unit and a trigger unit; The first comparison unit is connected to the trigger unit, the first comparison unit and the trigger unit are also connected to the sampling resistor, and the trigger unit is also connected to the controller; The first comparison unit is used to receive the sampled voltage, and output a first control signal to the trigger unit when the sampled voltage is less than the preset voltage, so that the trigger unit outputs a first signal to the controller according to the first control signal; as well as When the sampled voltage is greater than the preset voltage, a second control signal is output to the trigger unit, so that the trigger unit outputs a second signal to the controller according to the second control signal, thereby enabling the controller to control the action of the power tube in the converter.

3. The converter control circuit according to claim 2, characterized in that: The first comparison unit includes a comparator U2, a resistor R15, a resistor R17, a capacitor C10 and a capacitor C11; The non-inverting input terminal of the comparator U2 is connected to the sampling resistor through the resistor R17, the non-inverting input terminal of the comparator U2 is also grounded through the capacitor C10, the inverting input terminal of the comparator U2 is connected to the reference power supply through the resistor R15, the inverting input terminal of the comparator U2 is also grounded through the capacitor C11, and the output terminal of the comparator U2 is connected to the trigger unit.

4. The converter control circuit according to claim 3, characterized in that: The trigger unit includes a resistor R19, a resistor R20, a resistor R13, a resistor R18, a switch tube Q5, a comparator U3, a capacitor C7 and a capacitor C8; The control end of the switch tube Q5 is connected to the first comparison unit through the resistor R19, and the control end of the switch tube Q5 is also grounded through the resistor R20. The first end of the switch tube Q5 is connected to the non-inverting input end of the comparator U3, and the non-inverting input end of the comparator U3 is also connected to the reference power supply through the resistor R13. The non-inverting input end of the comparator U3 is also grounded through the capacitor C8. The inverting input end of the comparator U3 is connected to the sampling resistor through the resistor R18, and the inverting input end of the comparator U3 is also grounded through the capacitor C7. The output end of the comparator U3 is connected to the controller.

5. The converter control circuit according to any one of claims 1 to 4, characterized in that: The driving module includes a first control unit, a second comparison unit and a second control unit; The second comparison unit is connected to the first control unit and the second control unit respectively, the second comparison unit is also connected to the sampling resistor, the second control unit is also connected to the freewheeling tube in the converter, and the first control unit is also used to receive the pulse signal; The first control unit is used to control the second comparison unit to determine whether the sampling voltage is greater than a preset voltage when the pulse signal is at a first level, so that the second comparison unit outputs a first drive signal to the second control unit when the sampling voltage is greater than the preset voltage; and outputs a second drive signal to the second control unit when the sampling voltage is less than the preset voltage; as well as When the pulse signal is at a second level, controlling the second comparing unit to output a second driving signal to the second controlling unit; The second control unit is used for outputting an opening signal to the freewheeling tube in the converter when receiving the first driving signal, so that the freewheeling tube in the converter is opened according to the opening signal; as well as When the second driving signal is received, a shutdown signal is output to the converter, so that the freewheeling tube in the converter is turned off according to the shutdown signal.

6. The converter control circuit according to claim 5, characterized in that: The second comparison unit includes a comparator U4, a resistor R23 and a capacitor C14; The non-inverting input terminal of the comparator U4 is connected to the sampling resistor and the first control unit respectively, the inverting input terminal of the comparator U4 is connected to the reference power supply through the resistor R23, the inverting input terminal of the comparator U4 is also grounded through the capacitor C14, and the output terminal of the comparator U4 is connected to the second control unit.

7. The converter control circuit according to claim 5, characterized in that: The driving module also includes a delay unit; The delay unit is connected to the sampling resistor and the second comparison unit respectively; The delay unit is used to obtain the sampled voltage, and based on the magnitude of the sampled voltage, delay the sampled voltage by a corresponding time and then input it into the second comparison unit.

8. The converter control circuit according to claim 5, characterized in that: The second control unit includes a resistor R29, a resistor R30, a resistor R31, a resistor R32, a switch tube Q7, a switch tube Q8, a switch tube Q9 and a switch tube Q10; The control end of the switch tube Q7 is connected to the second comparison unit, the first end of the switch tube Q7 is connected to the control end of the switch tube Q8 through the resistor R30, the control end of the switch tube Q8 is also connected to the first power supply through the resistor R29, the second end of the switch tube Q8 is respectively connected to the control ends of the switch tube Q9 and the switch tube Q10 through the resistor R31, the control end of the switch tube Q10 is also grounded through the resistor R32, the first end of the switch tube Q8 and the first end of the switch tube Q9 are both connected to the first power supply, and the second end of the switch tube Q9 and the first end of the switch tube Q10 are also both connected to the freewheeling tube in the converter.

9. The converter control circuit according to any one of claims 1 to 4, characterized in that: The converter control circuit also includes an amplification module; The amplification module is respectively connected to the sampling resistor, the trigger module and the driving module; The amplifying module is used for receiving the sampling voltage output by the sampling resistor, and amplifying the sampling voltage and then outputting it to the triggering module and the driving module.

10. A conversion system, characterized in that: The transformation system comprises: Converter; Controller; and A converter control circuit as claimed in any one of claims 1 to 9.

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