Converter control circuit and conversion system

Abstract

The invention relates to the technical field of power supplies, and mainly provides a converter control circuit and a conversion system, the circuit comprises a time delay module, a sampling resistor and a trigger module, the sampling resistor and the trigger module are respectively connected with the time delay module, the sampling resistor is also used for connecting a converter, and the time delay module and the trigger module are also connected with a controller. The sampling resistor is used for outputting sampling voltage according to the change of inductive current in the converter. The delay module is used for receiving the sampling voltage according to a first driving signal when receiving the first driving signal output by the controller, delaying the sampling voltage for a corresponding time based on the size of the sampling voltage and outputting the sampling voltage to the trigger module, so that the trigger module outputs the sampling voltage to the controller when the sampling voltage is greater than the reference voltage. The controller controls the action of the switch tube in the converter, so that the action time of the switch tube is determined in real time according to the inductive current, long-time work of a body diode in the switch tube during heavy load is avoided, the loss of a power tube is reduced, and the conversion efficiency of the converter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power supplies, and particularly 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 voltage across 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 voltage across the parasitic capacitance of the switching tube to zero in a very short time, causing the conduction time of the anti-parallel diode inside the switching tube to be relatively long. And this working state increases the conduction loss of the converter to a certain extent, thereby reducing the conversion efficiency 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 and low conversion efficiency 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: to provide a converter control circuit, the converter control circuit includes a sampling resistor, a delay module, and a trigger module;

[0006] The sampling resistor is connected to the delay module, the delay module is connected to the trigger module, the sampling resistor is further used to connect to a converter, and both the delay module and the trigger module are also connected to a controller;

[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 delay module is configured to receive the sampling voltage according to the first driving signal when receiving the first driving signal output by the controller, and output the sampling voltage to the trigger module after delaying the corresponding time based on the magnitude of the sampling voltage;

[0009] The triggering module is configured to determine whether the sampled voltage is greater than a reference voltage after receiving the sampled voltage, and output a trigger signal to the controller when the sampled voltage is greater than the reference voltage, so that the controller controls the switching tube in the converter to act.

[0010] Optionally, the trigger signal is the moment when the first signal jumps to the second signal.

[0011] The delay module is further configured to receive a second driving signal output by the controller and output an offset voltage to the triggering module according to the second driving signal.

[0012] The triggering module is configured to receive the offset voltage and output a first signal to the controller after receiving the offset voltage; and

[0013] Receive the sampled voltage, and switch the first signal to a second signal and output it to the controller when the sampled voltage is greater than the reference voltage, so that the controller controls the switching tube in the converter to act at the moment of receiving the second signal.

[0014] Optionally, the delay module includes a control unit, an isolation unit, and a delay unit.

[0015] The isolation unit is respectively connected to the control unit and the sampling resistor, the isolation unit is further connected to the delay unit, the delay unit is connected to the triggering module, and the control unit is further connected to the controller.

[0016] The control unit is configured to stop working after receiving the first driving signal output by the controller, so as to control the isolation unit to receive and transmit the sampled voltage to the delay unit; and

[0017] Start working after receiving the second driving signal output by the controller, so that the isolation unit outputs an offset voltage to the triggered module.

[0018] The delay unit is configured to receive the sampled voltage and determine the delay time of the sampled voltage according to the magnitude of the sampled voltage, so as to delay the sampled voltage based on the delay time and output it to the triggering module.

[0019] Optionally, the control unit includes a switching tube Q6, a resistor R25, and a resistor R26.

[0020] The control terminal of the switching transistor Q6 is connected to the controller 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 connected to the isolation unit, and the second terminal of the switching transistor Q6 is used for grounding.

[0021] Optionally, the isolation unit includes a voltage follower U2, a resistor R24, and a capacitor C21;

[0022] The non-inverting input terminal of the voltage follower U2 is respectively connected to the resistor R24 and the control unit. The resistor R24 is connected to the sampling resistor. The inverting input terminal of the voltage follower U2 is connected to the output terminal of the voltage follower U2. The output terminal of the voltage follower U2 is connected to the delay unit.

[0023] Optionally, the delay unit includes a resistor R21 and a capacitor C13;

[0024] The resistor R21 is respectively connected to the isolation unit and the capacitor C13. The first terminal of the capacitor C13 is connected to the trigger module, and the second terminal of the capacitor C13 is used for grounding.

[0025] Optionally, the trigger module includes a comparator U3, a resistor R27, and a capacitor C14;

[0026] The non-inverting input terminal of the comparator U3 is grounded through the resistor R27. The non-inverting input terminal of the comparator U3 is also used to receive a reference voltage. The capacitor C14 is connected in parallel with the resistor R27. The inverting input terminal of the comparator U3 is connected to the delay module. The output terminal of the comparator U3 is connected to the controller.

[0027] Optionally, the trigger module further includes a resistor R23;

[0028] The resistor R23 is connected to the non-inverting input terminal of the comparator U3. The resistor R23 is used to receive the first drive signal or the second drive signal.

[0029] Optionally, the converter control circuit further includes an amplification module;

[0030] The amplification module is respectively connected to the sampling resistor and the delay module;

[0031] The amplification module is used to receive the sampling voltage output by the sampling resistor and amplify the sampling voltage and then output it to the delay module.

[0032] Optionally, the amplification module includes a differential amplifier U1 and a resistor R8;

[0033] Two input terminals of the differential amplifier U1 are respectively connected to two ends of the sampling resistor. The non-inverting input terminal of the differential amplifier U1 is further used to connect to a first power supply. The output terminal of the differential amplifier U1 is connected to the delay module. The resistor R8 is respectively connected to the output terminal of the differential amplifier U1 and the inverting input terminal of the differential amplifier U1.

[0034] 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:

[0035] A converter;

[0036] A controller; and

[0037] The converter control circuit as described above.

[0038] Different from the related art, the present invention provides a converter control circuit and a conversion system. The circuit includes a sampling resistor, a delay module, and a trigger module. The sampling resistor is connected to the delay module. The delay module is connected to the trigger module. The sampling resistor is further used to connect to a converter. Both the delay module and the trigger module are also connected to a controller. The sampling resistor responds to a change in the inductor current in the converter to output a corresponding sampling voltage based on the real-time changing inductor current. The delay module is used to receive the sampling voltage according to the first driving signal when receiving the first driving signal output by the controller, and delay the sampling voltage by a corresponding time based on the magnitude of the sampling voltage and then output it to the trigger module, so that when the sampling voltage is greater than the reference voltage, the trigger module controls the switching tube in the converter to act through the controller, so as to realize determining the action time of the switching tube in real time according to the magnitude of the inductor current, thereby avoiding the body diode in the switching tube from working for a long time under heavy load, and further reducing the loss of the power tube and improving the conversion efficiency of the converter. Description of the Drawings

[0039] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0040] Figure 1 is a structural block diagram of a conversion system provided by an embodiment of the present invention;

[0041] Figure 2a is a circuit diagram of a Buck converter provided by an embodiment of the present invention;

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

[0043] Figure 3 It is a waveform diagram of the operation of a converter provided by an embodiment of the present invention;

[0044] Figure 4 It is a structural block diagram of a converter control circuit provided by an embodiment of the present invention;

[0045] Figure 5 It is a circuit diagram of a converter control circuit provided by an embodiment of the present invention. Detailed implementation manners

[0046] In order to make the objectives, technical solutions and advantages of the present invention clearer, 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.

[0047] 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 sequence 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 sequence from that in the flowchart.

[0048] 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 embodiments 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.

[0049] 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 Figure 1 shown, 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 based on the change of the output current, output a corresponding trigger signal to the controller 20, so that the controller 20 controls the on and off of the switching tube in the converter 10 based on the trigger signal. Among them, the converter 10 can be a Buck converter or a Boost converter.

[0050] Further, taking the Buck converter as an example, please refer to Figure 2a , Figure 2aThe circuit diagram of a Buck converter provided by an embodiment of the present invention is as follows Figure 2a As 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 terminals of the switching transistor Q1 and the switching transistor Q2 are both connected to the controller 20.

[0051] 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 capacitances. During the on and off process of the switching transistor Q1 and the switching transistor Q2, these parasitic capacitances will store voltage, which will lead to relatively large losses when the switching transistor Q1 and the switching transistor Q2 are turned off or on. Therefore, when implementing voltage conversion through switching transistors, it is necessary to ensure that the switching transistor Q1 and the switching transistor Q2 are in a soft-switching state to reduce the losses of the switching transistors, thereby improving the service life of the converter 10.

[0052] 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 capacitance of the switching transistor Q2 only after the switching transistor Q2 is turned off, the voltage stored in the parasitic capacitance when the switching transistor Q2 operates is 0, thus realizing the soft turn-off of the switching transistor Q2.

[0053] After the switching transistor Q2 is turned off, the resonant inductor Lr resonates with the parasitic capacitances 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 capacitance of the switching transistor Q2 starts to increase in the positive direction, and the voltage u C1 (t) of the parasitic capacitance of the switching transistor Q1 decreases in the positive direction. During the resonance process, the voltage on the parasitic capacitance of the switching transistor Q2 increases in the positive direction to the maximum value (Vpm ), 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, so that the inductor current in the resonant inductor Lr starts to decrease 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, thereby achieving soft turn-on of the switching transistor Q1.

[0054] 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.

[0055] 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, so that the voltage stored in the parasitic capacitance of the switching transistor Q1 continues to increase, while the voltage stored in the parasitic capacitance of the switching transistor Q2 continues to decrease, and the inductor current also continues to decrease. When the voltage stored in the parasitic capacitance of the switching transistor Q2 is 0, the switching transistor Q2 conducts, thereby achieving soft turn-on of the switching transistor Q2.

[0056] In another embodiment, when the converter 10 is a Boost converter, as Figure 2b shown, the 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 transistor Q3 and the switching transistor Q4 are connected in series. The second end of the switching transistor Q3 also receives the input voltage through the resonant inductor Lm. The capacitor C4 is connected to the first end of the switching transistor Q3 and the second end of the switching transistor Q4 respectively. The control ends of the switching transistor Q3 and the switching transistor Q4 are also both connected to the controller 20. Among them, the working principle of the Boost converter is similar to that of the Buck converter, and will not be elaborated here.

[0057] It can be known that the voltages stored in the parasitic capacitances of switching transistors Q1 and Q2 are closely related to the inductor current, and the inductor current is affected by the load condition of converter 10. Therefore, in order to accurately achieve soft switching of the switching transistors in converter 10, the present application introduces converter control circuit 30, which monitors the inductor current of resonant inductor Lr in real time through the converter control circuit 30, and determines the action time of the switching transistors in converter 10 according to the magnitude of the inductor current, so as to ensure that no matter what load condition converter 10 is in, the switching transistors in converter 10 are soft turned on or soft turned off.

[0058] In some embodiments, please refer to Figure 4 , Figure 4 which 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 sampling resistor R5, delay module 31, and trigger module 32.

[0059] The sampling resistor R5 is connected to the delay module 31, the delay module 31 is connected to the trigger module 32, the sampling resistor R5 is also used to connect to converter 10, and both the delay module 31 and the trigger module 32 are also connected to controller 20;

[0060] The sampling resistor R5 responds to the change in the inductor current in converter 10 and outputs a corresponding sampling voltage based on the changing inductor current;

[0061] The delay module 31 is used to receive the sampling voltage according to the first drive signal when receiving the first drive signal output by the controller 20, and delay the sampling voltage by a corresponding time based on the magnitude of the sampling voltage and then output it to the trigger module 32;

[0062] The trigger module 32 is used to determine whether the sampling voltage is greater than the reference voltage after receiving the sampling voltage, and when the sampling voltage is greater than the reference voltage, output a trigger signal to the controller 20 to enable the controller 20 to control the switching transistors in converter 10 to act.

[0063] It can be known that the converter control circuit 30 mainly detects the inductor current in the converter 10 in real time through the sampling resistor R5, and determines the on and off times of the switching transistors in the converter 10 based on the magnitude of the inductor current, so as to achieve soft switching of the switching transistors.

[0064] Specifically, after the delay module 31 receives the first driving signal output by the controller 20, it will receive the sampling voltage output by the sampling resistor R5 based on the inductor current, and delay the corresponding time based on the magnitude of the sampling voltage and then output the sampling voltage to the trigger module 32. After receiving the sampling voltage, the trigger module 32 will judge the magnitude of the sampling voltage and the reference voltage, and when the sampling voltage is greater than the reference voltage, output a trigger signal to the controller 20, so that the controller 20 controls the switching tube in the converter 10 to act based on the trigger signal. It should be noted that the reference 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 reference voltage, and vice versa.

[0065] It can be known that when the converter 10 is in a heavy load state, the peak value of the inductor current will be very large when the power tube in the converter 10 is turned off, so that the voltage at the parasitic capacitor terminal 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 will be very small, so that the time for the parasitic capacitor to resonate to zero is longer. In order to realize the soft switching of the switching tube Q1 and the switching tube Q2, the voltage on the parasitic capacitors of the switching tube Q1 and the switching tube Q2 needs to be zero. Therefore, when realizing the soft switching of the switching tube in the converter 10, the inductor current is collected in real time, and the delay time of the delay module 31 is determined according to the magnitude of the inductor current, so as to control the time of the output trigger signal, so that no matter how the load condition of the converter 10 changes, the switching tube is in soft switching, reducing the loss of the converter 10.

[0066] In some embodiments, when the trigger signal is the moment when the first signal jumps to the second signal, the delay module 31 is further configured to receive the second driving signal output by the controller 20 and output an offset voltage to the trigger module 32 according to the second driving signal;

[0067] The trigger module 32 is configured to receive the offset voltage and output the first signal to the controller 20 after receiving the offset voltage; and

[0068] receive the sampling voltage, and when the sampling voltage is greater than the reference voltage, switch the first signal to the second signal and then output it to the controller 20, so that the controller 20 controls the switching tube in the converter 10 to act at the moment of receiving the second signal.

[0069] Specifically, when the controller 20 outputs a second driving signal to the delay module 31, the delay module 31 stops receiving the sampling voltage and outputs an offset voltage to the trigger module 32 according to the second driving signal, so that the trigger module 32 outputs a first signal to the controller 20 according to the offset voltage. When the controller 20 outputs a first driving signal to the delay module 31 and the sampling voltage is greater than the reference voltage, the trigger module 32 receives the sampling voltage output by the delay module 31 and outputs a second signal to the controller 20 based on the sampling voltage, so that the controller 20 outputs a trigger signal to the switching tube in the converter 10 at the moment of receiving the second signal, thereby making the switching tube soft-switch.

[0070] It can be known that the switching tubes in the converter 10 include a switching tube Q1 and a switching tube Q2, and the trigger signal output by the converter control circuit 30 can control the soft-switching of the switching tube Q1 or the soft-switching of the switching tube Q2. When the controller 20 controls the soft-switching of the switching tube Q1 according to the trigger signal, the first driving signal and the second driving signal are output by the controller 20 according to the current state of the switching tube Q2. If the controller 20 controls the soft-switching of the switching tube Q2 according to the trigger signal, the first driving signal and the second driving signal are output by the controller 20 according to the current state of the switching tube Q1.

[0071] 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 will control the switching tube Q1 and the switching tube Q2 to act. 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 tube Q1 or the switching tube Q2 to act.

[0072] In yet another embodiment, the delay module 31 includes a control unit 311, an isolation unit 312, and a delay unit 313;

[0073] The isolation unit 312 is respectively connected to the control unit 311 and the sampling resistor R5, the isolation unit 312 is also connected to the delay unit 313, the delay unit 313 is connected to the trigger module 32, and the control unit 311 is also connected to the controller 20;

[0074] The control unit 311 is configured to stop working after receiving the first driving signal output by the controller 20, so as to control the isolation unit 312 to receive and transmit the sampling voltage to the delay unit 313; and

[0075] start working after receiving the second driving signal output by the controller 20, so that the isolation unit 312 outputs an offset voltage to the trigger module 32;

[0076] The delay unit 313 is configured to receive the sampling voltage, determine the delay time of the sampling voltage according to the magnitude of the sampling voltage, and output the sampled voltage to the trigger module 32 after delaying it based on the delay time.

[0077] Specifically, the sampling resistor R5 outputs a sampling voltage to the delay module 31 in real time based on the inductor current on the resonant inductor Lr. When the control unit 311 receives the second driving signal output by the controller 20, the control unit 311 starts to work, so that the isolation unit 312 outputs an offset voltage to the trigger module 32. When the control unit 311 receives the first driving signal output by the controller 20, it stops working according to the first driving signal, so that the sampling voltage is input to the isolation unit 312. When the isolation unit 312 receives the sampling voltage, it inputs the sampling voltage to the delay unit 313, so that the delay unit 313 delays the sampling voltage by a preset time based on the magnitude of the sampling voltage and inputs it to the trigger module 32. 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 in the converter 10, thus affecting the delay time of the delay unit 313. Therefore, the delay time of the delay unit 313 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.

[0078] 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 control unit 311 includes a switching tube Q6, a resistor R25, and a resistor R26; the isolation unit 312 includes a voltage follower U2, a resistor R24, and a capacitor C21; the delay unit 313 includes a resistor R21 and a capacitor C13;

[0079] The control terminal of the switching transistor Q6 is connected to the controller 20 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 connected to the isolation unit 312, and the second terminal of the switching transistor Q6 is used for grounding.

[0080] The non-inverting input terminal of the voltage follower U2 is respectively connected to the resistor R24 and the control unit. The resistor R24 is connected to the sampling resistor R5. The inverting input terminal of the voltage follower U2 is connected to the output terminal of the voltage follower U2. The output terminal of the voltage follower U2 is connected to the delay unit 313.

[0081] The resistor R21 is respectively connected to the isolation unit 312 and the capacitor C13. The first terminal of the capacitor C13 is connected to the trigger module 32, and the second terminal of the capacitor C13 is used for grounding.

[0082] Specifically, when the controller 20 outputs a second driving signal, the switching transistor Q6 will conduct according to the second driving signal (that is, the control unit 311 starts to work), thereby pulling down the voltage of the non-inverting input terminal of the voltage follower U2. At this time, the voltage follower U2 will output an offset voltage to the trigger module 32. When the controller 20 outputs a first driving signal, the switching transistor Q6 will stop working according to the first driving signal, so that the sampling voltage is input to the non-inverting input terminal of the voltage follower U2 through the resistor R4. When the non-inverting input terminal of the voltage follower U2 receives the sampling voltage, it will directly input the sampling voltage to the capacitor C13 to charge the capacitor C13. After the capacitor C13 is charged for a corresponding time, it will input the sampling voltage to the trigger module 32. Among them, since the capacitance of the capacitor C13 is fixed, the larger the sampling voltage, the faster the capacitor C13 charges, and the faster the trigger module 32 receives the sampling voltage.

[0083] In another real-time example, as Figure 5 shown, the trigger module 32 includes a comparator U3, a resistor R27, and a capacitor C14;

[0084] The non-inverting input terminal of the comparator U3 is grounded through the resistor R27. The non-inverting input terminal of the comparator U3 is also used to receive a reference voltage. The capacitor C14 is connected in parallel with the resistor R27. The inverting input terminal of the comparator U3 is connected to the delay module 31, and the output terminal of the comparator U3 is connected to the controller 20.

[0085] Specifically, after the delay module 31 outputs the offset voltage, the inverting input terminal of the comparator U3 receives the offset voltage and outputs a first signal to the controller 20 based on the offset voltage; and after the delay module 31 outputs the sampling voltage, the comparator U3 compares the magnitudes of the sampling voltage and the reference voltage, and when the sampling voltage is greater than the reference voltage, the comparator U3 outputs a second signal to the controller 20. At this time, the controller 20 receives the trigger signal (the moment when the first signal jumps to the second signal) and controls the soft switching of the switching tube in the converter 10 according to the trigger signal.

[0086] In another embodiment, as Figure 5 shown, the trigger module 32 further includes a resistor R23, and the resistor R23 is connected to the non-inverting input terminal of the comparator U3, and the non-inverting input terminal of the comparator U3 is used to receive the first drive signal or the second drive signal through the resistor R23. It should be noted that when the switching tube Q6 is turned off based on the received first drive signal, the voltage follower U2 charges the capacitor C13 according to the sampling voltage; at the same time, the non-inverting input terminal of the comparator U3 also receives the first drive signal, thereby pulling down the voltage of the non-inverting input terminal of the comparator U3. After voltage division and the action of the reference voltage, a preset voltage is sent to the non-inverting input terminal of the comparator, so that the comparator U3 can quickly output a first signal. And when the switching tube Q6 is turned on according to the second drive signal, the voltage follower U2 outputs the offset voltage, and the capacitor C13 starts to discharge based on the voltage follower U2; at the same time, the non-inverting input terminal of the comparator U3 also receives the second drive signal, thereby raising the voltage of the non-inverting input terminal of the comparator U3, so that the comparator U3 can quickly output a second signal. Based on this, the response speed of the comparator U3 can be improved, thereby improving the reliability of the converter control circuit 30.

[0087] 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 delay module 31, and the trigger module 32;

[0088] 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 connection of the delay module 31 and the trigger module 32.

[0089] Specifically, after the sampling resistor R5 outputs a 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 delay module 31 and the second 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, and the sampling voltage is amplified by the amplification module 33, thereby improving the switching accuracy of the converter 10.

[0090] In some embodiments, as Figure 5 shown, the amplification module 33 includes a differential amplifier U1 and a resistor R8;

[0091] 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 also used to connect to the first power supply V RF1 , the output terminal of the differential amplifier U1 is connected to the delay module 31, and the resistor R8 is respectively connected to the output terminal of the differential amplifier U1 and the inverting input terminal of the differential amplifier U1.

[0092] Among them, the differential amplifier refers to a device that amplifies the difference between two input signals. Therefore, when there is current flowing 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) across the sampling resistor R5, amplify the voltage drop, and finally input the amplified sampling voltage to the delay module 31.

[0093] In yet another real-time example, please refer to Figure 2a and Figure 5, taking the Buck converter and the triggering signal to control the operation of the switching transistor Q2 as an example. When the switching transistor Q1 is turned on, the controller 20 will output a second driving signal to the switching transistor Q6 according to the switching transistor Q1. When the switching transistor Q6 receives the second driving signal, it will start to work according to the second driving signal, thereby pulling down the voltage at the non-inverting input terminal of the voltage follower U2. At this time, the sampled voltage will also flow into the ground terminal through the switching transistor Q6. When the voltage at the non-inverting input terminal of the voltage follower U2 is pulled down, since the voltage follower U2 is a voltage follower, the voltage follower U2 will output a low voltage (offset voltage) at this time. When the comparator U3 receives the offset voltage, and this offset voltage is less than the reference voltage, the comparator U3 will output a high-level signal (the first signal) to the controller 20, and the controller 20 will only control the switching transistor Q2 to operate at the moment when the first signal jumps to the second signal, so the switching transistor Q2 does not operate at this time. When the switching transistor Q1 is turned off, the resonant inductor Lr and the parasitic capacitances of the switching transistors Q1 and Q2 start to resonate. At this time, the controller 20 will also output a first driving signal based on the switching transistor Q1. When the switching transistor Q6 receives the first driving signal, it will stop working according to the first driving signal, so that the sampled voltage is directly input to the voltage follower U2. When the voltage follower U2 receives the sampled voltage, it will input the sampled voltage into the capacitor C13 to charge the capacitor C13. Among them, due to the influence of the load condition on the inductor current, it affects the charging speed of the capacitor C13. When the converter 10 is heavily loaded, the capacitor C13 will be quickly charged, and the voltage at the inverting input terminal of the comparator U3 will also be quickly pulled up, thereby outputting a low-level signal (the second signal) to the controller 20. When the controller 20 receives the second signal instantaneously, it starts to control the switching transistor Q2 to turn on softly. Based on this, regardless of the load condition of the converter 10, the soft switching of the switching transistors in the converter 10 can be realized, thereby reducing the loss of the converter, and further improving the stability and safety of the converter.

[0094] An embodiment of the present invention provides a converter control circuit, which includes a sampling resistor, a delay module, and a trigger module; the sampling resistor is connected to the delay module, the delay module is connected to the trigger module, the sampling resistor is further used to connect to a converter, and both the delay module and the trigger module are also connected to a controller. The sampling resistor responds to the change in the inductor current in the converter to output a corresponding sampling voltage based on the real-time changing inductor current. The delay module is used to receive the sampling voltage according to the first driving signal when receiving the first driving signal output by the controller, and output the sampling voltage to the trigger module after delaying the corresponding time based on the magnitude of the sampling voltage, so that when the sampling voltage is greater than the reference voltage, the trigger module controls the switching tube in the converter to act through the controller, so as to realize determining the action time of the switching tube in real time according to the magnitude of the inductor current, thereby avoiding the body diode in the switching tube from working for a long time under heavy load, and further reducing the loss of the power tube and improving the conversion efficiency of the converter.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 variations 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 recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to 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 delay module and a trigger module; The sampling resistor is connected to the delay module, the delay module is connected to the trigger module, the sampling resistor is also used to connect a converter, and the delay module and the trigger module are also connected to a controller; 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 delay module is used for receiving the sampled voltage according to the first drive signal output by the controller, and outputting the sampled voltage to the trigger module after delaying the sampled voltage for a corresponding time based on the size of the sampled voltage; The trigger module is used to determine whether the sampled voltage is greater than a reference voltage after receiving the sampled voltage, and output a trigger signal to the controller when the sampled voltage is greater than the reference voltage, so that the controller controls the action of the switch tube in the converter.

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. The delay module is also used to receive a second driving signal output by the controller, and output an offset voltage to the trigger module according to the second driving signal; The trigger module is used to receive the offset voltage, and output a first signal to the controller after receiving the offset voltage; as well as The sampling voltage is received, and when the sampling voltage is greater than the reference voltage, the first signal is switched to a second signal and then output to the controller, so that the controller controls the action of the switch tube in the converter at the moment of receiving the second signal.

3. The converter control circuit according to claim 2, characterized in that: The delay module includes a control unit, an isolation unit and a delay unit; The isolation unit is connected to the control unit and the sampling resistor respectively, the isolation unit is also connected to the delay unit, the delay unit is connected to the trigger module, and the control unit is also connected to the controller; The control unit is used to stop working after receiving the first driving signal output by the controller, so as to control the isolation unit to receive and transmit the sampling voltage to the delay unit; as well as After receiving the second driving signal output by the controller, the operation starts, so that the isolation unit outputs an offset voltage to the triggered module; The delay unit is used to receive the sampled voltage and determine a delay time of the sampled voltage according to the magnitude of the sampled voltage, so as to delay the sampled voltage based on the delay time and output it to the trigger module.

4. The converter control circuit according to claim 3, characterized in that: The control unit includes a switch tube Q6, a resistor R25 and a resistor R26; The control end of the switch tube Q6 is connected to the controller through the resistor R25, and the control end of the switch tube Q6 is also grounded through the resistor R26. The first end of the switch tube Q6 is connected to the isolation unit, and the second end of the switch tube Q6 is used for grounding.

5. The converter control circuit according to claim 3, characterized in that: The isolation unit includes a voltage follower U2, a resistor R24 ​​and a capacitor C21; The in-phase input terminal of the voltage follower U2 is connected to the resistor R24 ​​and the control unit respectively, the resistor R24 ​​is connected to the sampling resistor, the inverting input terminal of the voltage follower U2 is connected to the output terminal of the voltage follower U2, and the output terminal of the voltage follower U2 is connected to the delay unit.

6. The converter control circuit according to claim 3, characterized in that: The delay unit includes a resistor R21 and a capacitor C13; The resistor R21 is connected to the isolation unit and the capacitor C13 respectively. A first end of the capacitor C13 is connected to the trigger module, and a second end of the capacitor C13 is grounded.

7. The converter control circuit according to claim 2, characterized in that: The trigger module includes a comparator U3, a resistor R27 and a capacitor C14; The non-inverting input terminal of the comparator U3 is grounded through the resistor R27, and the non-inverting input terminal of the comparator U3 is also used to receive a reference voltage. The capacitor C14 is connected in parallel with the resistor R27, the inverting input terminal of the comparator U3 is connected to the delay module, and the output terminal of the comparator U3 is connected to the controller.

8. The converter control circuit according to claim 7, characterized in that: The trigger module also includes a resistor R23; The resistor R23 is connected to the non-inverting input terminal of the comparator U3 , and the resistor R23 is used to receive the first driving signal or the second driving signal.

9. The converter control circuit according to any one of claims 1 to 8, characterized in that: The converter control circuit also includes an amplification module; The amplification module is connected to the sampling resistor and the delay module respectively; The amplification module is used to receive the sampling voltage output by the sampling resistor, and amplify the sampling voltage and output it to the delay module.

10. The converter control circuit according to claim 9, characterized in that: The amplification module includes a differential amplifier U1 and a resistor R8; The two input ends of the differential amplifier U1 are respectively connected to the two ends of the sampling resistor, the non-inverting input end of the differential amplifier U1 is also used to connect to the first power supply, the output end of the differential amplifier U1 is connected to the delay module, and the resistor R8 is respectively connected to the output end of the differential amplifier U1 and the inverting input end of the differential amplifier U1.

11. 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 10.

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