Current detection circuit applied to flyback circuit and energy storage power supply

Abstract

The invention relates to a current detection circuit applied to a flyback circuit and an energy storage power supply. The current detection circuit comprises a one-way conduction module, a control module and an equivalent output module which are connected in sequence, and the control module is further used for receiving a driving signal. The control module is used for controlling the equivalent output module to work under the condition that the driving signal is a first signal and controlling the equivalent output module to stop working under the condition that the driving signal is a second signal, and the equivalent output module is used for responding to the voltage of the sampling end of the flyback circuit and the conduction voltage drop of the one-way conduction module when the equivalent output module works. And determining a current detection result of the flyback circuit. The first signal is a driving signal for driving a power tube of the flyback circuit to be conducted, and the second signal is a driving signal for driving the power tube to be cut off. By adopting the current detection circuit, the accuracy of a current detection result can be improved.

Description

Technical Field

[0001] The present application relates to the field of power technologies, and in particular, to a current detection circuit and an energy storage power supply applied to a flyback circuit. Background Art

[0002] With the rapid development of power electronics technologies, higher requirements are also imposed on the functions, performance, and reliability of power supply products. Therefore, it is necessary to strictly require the performance indicators of each circuit in the power supply product and accurately detect the electrical parameters in the power supply product.

[0003] The flyback circuit is a common circuit in power supply products, which uses the principle of electromagnetic conversion to obtain the required output voltage. When the flyback circuit operates in the Discontinuous Conduction Mode (DCM), it is necessary to detect the winding current of the primary winding of the transformer in the high-frequency chopper of the flyback circuit.

[0004] However, due to the existence of parasitic parameters in the flyback circuit, the accuracy of the current detection result of the current flyback circuit is not high. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a current detection circuit and an energy storage power supply applied to a flyback circuit with relatively good accuracy.

[0006] In a first aspect, the present application provides a current detection circuit applied to a flyback circuit, including a unidirectional conduction module, a control module, and an equivalent output module connected in sequence. The unidirectional conduction module is connected to the sampling terminal of the flyback circuit, the equivalent output module is connected to the unidirectional conduction module and the control module respectively, and the control module is further configured to receive a driving signal for controlling the working state of the flyback circuit;

[0007] The control module is configured to control the equivalent output module to work when the driving signal is a first signal, and control the equivalent output module to stop working when the driving signal is a second signal, where the first signal is a driving signal for driving the power tube of the flyback circuit to conduct, and the second signal is a driving signal for driving the power tube to cut off;

[0008] The equivalent output module is configured to, when working, determine the current detection result of the flyback circuit in response to the voltage at the sampling terminal of the flyback circuit and the conduction voltage drop of the unidirectional conduction module.

[0009] In one embodiment, the equivalent output module includes an energy storage element; both the control module and the energy storage element are connected to an auxiliary power supply;

[0010] The control module is used to be in the cut-off state when the drive signal is the first signal, so as to control the first path between the auxiliary power supply and the energy storage element to conduct, enabling the energy storage element to be charged through the auxiliary power supply; and to be in the conducting state when the drive signal is the second signal, so as to control the second path between the auxiliary power supply and the control module to conduct, stopping the auxiliary power supply from charging the energy storage element.

[0011] The equivalent output module is used to control the unidirectional conduction module to conduct and clamp the voltage of the energy storage element when the voltage of the energy storage element is greater than the sum of the voltage at the sampling terminal and the conduction voltage drop, so as to determine the current detection result according to the voltage of the energy storage element.

[0012] In one embodiment, the control module includes a first transistor; the emitter of the first transistor is respectively connected to the unidirectional conduction module and the first end of the energy storage element, the base of the first transistor is used to receive the drive signal, the first end of the energy storage element is also connected to the auxiliary power supply, and the collector of the first transistor and the second end of the energy storage element are both connected to the first ground terminal.

[0013] In one embodiment, the unidirectional conduction module includes a first diode; the positive electrode of the first diode is connected to the equivalent output module, and the negative electrode of the first diode is connected to the sampling terminal.

[0014] In one embodiment, the current detection circuit further includes a compensation module, the compensation module is connected to the equivalent output module, and the conduction voltage drop of the compensation module is the same as that of the unidirectional conduction module;

[0015] The equivalent output module is used to determine the output voltage in response to the voltage at the sampling terminal and the conduction voltage drop of the unidirectional conduction module during operation;

[0016] The compensation module is used to compensate the output voltage of the equivalent output module according to the conduction voltage drop of the compensation module to obtain a compensation voltage, and to determine the current detection result according to the compensation voltage.

[0017] In one embodiment, the compensation module includes a second diode; the positive electrode of the second diode is connected to the equivalent output module, and the negative electrode of the second diode is connected to the output terminal of the current detection circuit.

[0018] In one embodiment, the current detection circuit further includes an operation module, and the operation module is connected to the equivalent output module;

[0019] The operation module is used to determine the current detection result according to the output voltage of the equivalent output module.

[0020] In one embodiment, the current detection circuit further includes a pull-up current-limiting resistor, and the pull-up current-limiting resistor is arranged between the auxiliary power supply and the equivalent output module;

[0021] The sampling terminal includes a sampling resistor. The first end of the sampling resistor is respectively connected to the emitter of the power transistor and the unidirectional conduction module, and the second end of the sampling resistor is connected to the second grounding terminal.

[0022] The resistance value of the pull-up current-limiting resistor is greater than that of the sampling resistor.

[0023] In one embodiment, the second grounding terminal is the power grounding terminal of the flyback circuit, and the first grounding terminal corresponding to the equivalent output module is connected to the second grounding terminal through a bus capacitor.

[0024] In a second aspect, the present application also provides an energy storage power supply, which includes a flyback circuit and the current detection circuit of any one of the above.

[0025] In the above current detection circuit and energy storage power supply applied to the flyback circuit, the current detection circuit includes a unidirectional conduction module, a control module, and an equivalent output module connected in sequence. The unidirectional conduction module is connected to the sampling terminal of the flyback circuit, the equivalent output module is respectively connected to the unidirectional conduction module and the control module, and the control module is further configured to receive a driving signal, and the driving signal is used to control the working state of the flyback circuit. Since the first signal is the driving signal for driving the power transistor of the flyback circuit to conduct, and the second signal is the driving signal for driving the power transistor to cut off, and the control module can control the equivalent output module to work when the driving signal is the first signal, and control the equivalent output module to stop working when the driving signal is the second signal. Therefore, during the process of driving the power transistor of the flyback circuit to conduct through the first signal, the influence of the oscillation of parasitic parameters on the voltage of the sampling terminal can be reduced through the unidirectional conduction module. Furthermore, when the equivalent output module is working, it can accurately determine the current detection result of the flyback circuit in response to the voltage of the sampling terminal of the flyback circuit and the conduction voltage drop of the unidirectional conduction module. And, during the process of driving the power transistor of the flyback circuit to cut off through the second signal, by stopping the equivalent output module from working, the current spike caused by the moment when the flyback circuit is turned off can also be effectively avoided. In this way, the accuracy of the current detection result can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a sampling schematic diagram of the flyback circuit;

[0028] Figure 2 It is a schematic diagram of the current waveform in the flyback circuit;

[0029] Figure 3 Schematic diagram of a current detection circuit applied to a flyback circuit in an embodiment;

[0030] Figure 4 Schematic diagram of an equivalent output module in an embodiment;

[0031] Figure 5 Schematic diagram of another current detection circuit in an embodiment;

[0032] Figure 6 Schematic diagram of another current detection circuit in an embodiment;

[0033] Figure 7 Schematic diagram of another current detection circuit in an embodiment;

[0034] Figure 8 Schematic diagram of an energy storage power supply in an embodiment. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application 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 application and are not used to limit the present application.

[0036] The flyback circuit can use the electromagnetic conversion principle to achieve the required output voltage. It can be understood as a high-frequency chopper, and the sampling of the dynamic current in the high-frequency chopper is relatively complex.

[0037] Figure 1 Sampling schematic diagram of the flyback circuit, Figure 1 Figure (a) in Figure 1 shows a sampling circuit of an ideal flyback circuit. As shown in Figure (a) in Figure 1 the sampling circuit of the flyback circuit may include a power supply BUS+, a resistor R1, a capacitor C1, a snubber diode D1, a transformer T1, a diode D2, a capacitor C2, a power transistor Q1, a resistor R2, a resistor R3, and a sampling resistor R4. The current IP in the primary winding of the transformer T1 in the flyback circuit is equivalent to the current in the sampling resistor R4. Therefore, the current in the sampling resistor R4 can be used to detect the current IP in the primary winding of the transformer T1 in the flyback circuit.

[0038] Figure 2 Schematic diagram of the current waveform in the flyback circuit, Figure 2 Figure (a) in Figure 1 is the current waveform diagram corresponding to Figure (a) in Figure 2As shown in Figure (a), if the power transistor Q1 is driven according to the driving signal PWM, the current IP in the primary winding will also change correspondingly. It can be understood that the driving signal can be achieved by pulse width modulation.

[0039] Figure 1 Figure (b) shows a schematic diagram of an equivalent circuit. Based on Figure (a), the sampling circuit of the actual flyback circuit is as Figure 1 shown in Figure (b). There are parasitic parameters in the power transistor Q1, the absorption diode D1, and the printed circuit board (PCB). The parasitic parameters will affect the current characteristics of the flyback circuit during the transient period of the power transistor Q1 turning on and off, resulting in an inaccurate current signal being sampled on the sampling resistor R4. Figure 1 Figure (b) is the current waveform diagram corresponding to Figure (b). As shown by the circular dotted line mark, if the power transistor Q1 is driven according to the driving signal PWM, the actual current IP in the primary winding is as

[0040] Figure 2 shown in Figure (b). Among them, the oscillation caused by the parasitic parameters Cr1 of the absorption diode D1, the parasitic parameters Cr3 and Cr4 of the power transistor Q1, and the parasitic parameters Lr1 and Lr2 of the PCB will cause spikes at the rising start point and the turn-off point of the current IP in the primary winding. Figure 1 shown in Figure (b). Figure 2 As can be seen, the oscillation generated by the parasitic parameters will lead to inaccurate current information being sampled, and further cause the power supply product to work unstably. Based on this, it is necessary to provide a current detection circuit with better accuracy. The following will introduce this current detection circuit. Figure 2 Figure (b) shows the current waveform corresponding to Figure (b). As shown by the circular dotted line mark, if the power transistor Q1 is driven according to the driving signal PWM, the actual current IP in the primary winding is as shown in Figure (b). Among them, the oscillation caused by the parasitic parameters Cr1 of the absorption diode D1, the parasitic parameters Cr3 and Cr4 of the power transistor Q1, and the parasitic parameters Lr1 and Lr2 of the PCB will cause spikes at the rising start point and the turn-off point of the current IP in the primary winding.

[0041] It can be seen that the oscillation generated by the parasitic parameters will lead to inaccurate current information being sampled, and further cause the power supply product to work unstably. Based on this, it is necessary to provide a current detection circuit with better accuracy. The following will introduce this current detection circuit.

[0042] Figure 3 Figure shows a schematic diagram of a current detection circuit applied to a flyback circuit in an embodiment. As Figure 3 shown, the current detection circuit 300 includes a unidirectional conduction module 301, a control module 302, and an equivalent output module 303 connected in sequence.

[0043] Among them, the unidirectional conduction module 301 is connected to the sampling terminal 101 of the flyback circuit 100. The sampling terminal 101 is used to sample the electrical parameters of the flyback circuit 100. Optionally, the voltage of the sampling terminal 101 is determined according to the winding current of the primary winding in the flyback circuit 100. The following examples will all detect the winding current of the primary winding in the flyback circuit 100 by the sampling terminal 101.

[0044] The unidirectional conduction module 301 refers to a module that conducts unidirectionally when the current or voltage is greater than a preset threshold. The unidirectional conduction module 301 may include, but is not limited to, a diode, a diode array, or a thyristor. It can be understood that the unidirectional conduction module 301 has a conduction voltage drop.

[0045] Moreover, the equivalent output module 303 is respectively connected to the unidirectional conduction module 301 and the control module 302. The control module 302 is further configured to receive a driving signal. Wherein, the driving signal is used to control the working state of the flyback circuit 100. Optionally, the control module 302 may include at least one switching element, and the switching element includes, but is not limited to, an Insulated Gate Bipolar Transistor (IGBT) and a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET).

[0046] In this embodiment, the flyback circuit 100 includes a power transistor, and the driving signal includes a first signal and a second signal. The first signal is a driving signal for driving the power transistor of the flyback circuit 100 to conduct, and the second signal is a driving signal for driving the power transistor to cut off. Wherein, the first signal may be a high level, and the second signal may be a low level. Exemplarily, the current detection circuit 300 in the present application performs current detection when the driving signal is the first signal, that is, when driving the power transistor to conduct; while when the driving signal is the second signal, that is, when the power transistor is cut off, no current detection is performed.

[0047] Optionally, the base of the power transistor is used to receive the driving signal, the emitter of the power transistor is connected to the sampling terminal 101, and the collector of the power transistor is connected to the primary winding.

[0048] Furthermore, the control module 302 is configured to control the equivalent output module 303 to work when the driving signal is the first signal, and to control the equivalent output module 303 to stop working when the driving signal is the second signal. Exemplarily, the control module 302 is configured to bypass the equivalent output module 303 when the driving signal is the second signal to control the equivalent output module 303 to stop working, that is, to make the equivalent output module 303 stop outputting the detection signal. The control module 302 is configured not to bypass the equivalent output module 303 when the driving signal is the first signal, so that the equivalent output module 303 outputs the corresponding detection signal.

[0049] Further optionally, when the driving signal is the first signal, the control module 302 can control the path between the unidirectional conduction module 301 and the equivalent output module 303 to be turned on, so as to control the equivalent output module 303 to operate. When the driving signal is the second signal, the control module 302 can control the path between the unidirectional conduction module 301 and the equivalent output module 303 to be turned off, so as to control the equivalent output module 303 to stop operating.

[0050] In some embodiments, when the driving signal is the first signal, the control module can control the unidirectional conduction module to be turned on, so as to control the equivalent output module to operate. When the driving signal is the second signal, the control module can control the unidirectional conduction module to be turned off, so as to control the equivalent output module to stop operating.

[0051] The equivalent output module 303 is configured to, when operating, determine the current detection result of the flyback circuit 100 in response to the voltage of the sampling terminal 101 of the flyback circuit 100 and the conduction voltage drop of the unidirectional conduction module 301.

[0052] In this embodiment, optionally, when the equivalent output module 303 is operating, the output voltage of the equivalent output module 303 can be equal to the sum of the voltage of the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. Furthermore, the equivalent output module 303 can determine the current detection result of the flyback circuit 100 according to the output voltage of the equivalent output module 303. For example, when the equivalent output module 303 is operating, the equivalent output module 303 takes the difference between the output voltage of the equivalent output module 303 and the conduction voltage drop of the unidirectional conduction module 301 as the voltage of the sampling terminal 101, and obtains the current detection result according to the voltage of the sampling terminal 101.

[0053] It can be understood that when the equivalent output module 303 is not operating, the current detection result can be a default preset value, such as 0.

[0054] The above-mentioned current detection circuit 300 includes a one-way conduction module 301, a control module 302, and an equivalent output module 303 that are connected in sequence. The one-way conduction module 301 is connected to the sampling terminal 101 of the flyback circuit 100. The equivalent output module 303 is respectively connected to the one-way conduction module 301 and the control module 302. The control module 302 is further configured to receive a driving signal, and the driving signal is used to control the working state of the flyback circuit 100. Since the first signal is the driving signal for driving the power tube of the flyback circuit 100 to conduct, and the second signal is the driving signal for driving the power tube to cut off, and the control module 302 can control the equivalent output module 303 to work when the driving signal is the first signal, and control the equivalent output module 303 to stop working when the driving signal is the second signal. Therefore, during the process of driving the power tube of the flyback circuit 100 to conduct through the first signal, the influence of the oscillation of parasitic parameters on the voltage of the sampling terminal 101 can be reduced through the one-way conduction module 301. Furthermore, when the equivalent output module 303 is working, it can more accurately determine the current detection result of the flyback circuit 100 in response to the voltage of the sampling terminal 101 of the flyback circuit 100 and the conduction voltage drop of the one-way conduction module 301. And, during the process of driving the power tube of the flyback circuit 100 to cut off through the second signal, by stopping the equivalent output module 303 from working, the current spike caused by the instant turn-off of the flyback circuit 100 can also be effectively avoided. Thus, the accuracy of the current detection result can be improved.

[0055] Figure 4 FIG. is a schematic diagram of an equivalent output module in an embodiment, as Figure 4 shown. In an exemplary embodiment, optionally, the equivalent output module 303 includes an energy storage element 3031. Both the control module 302 and the energy storage element 3031 are connected to the auxiliary power supply 102. Among them, the energy storage element 3031 may include, but is not limited to, at least one capacitor, inductor, battery, or other energy storage elements. The connection of the auxiliary power supply 102 can be any form of current source or voltage source, such as a 5-volt (V) DC power supply, and this embodiment does not limit it.

[0056] In this embodiment, the control module 302 can be in a cut-off state when the driving signal is the first signal, and in a conducting state when the driving signal is the second signal.

[0057] Further, when the control module 302 is in a cut-off state, the first path between the auxiliary power supply 102 and the energy storage element 3031 is conducted. In this way, the auxiliary power supply 102 can charge the energy storage element 3031 to control the equivalent output module 303 to work through the control module 302.

[0058] When the control module 302 is in the conducting state, the second path between the auxiliary power supply 102 and the control module 302 is conducting to bypass the equivalent output module 303. The auxiliary power supply 102 stops charging the energy storage element 3031, and the control module 302 is used to control the equivalent output module 303 to stop working.

[0059] In some embodiments, when the control module 302 is in the conducting state, the second path between the auxiliary power supply 102 and the control module 302 is conducting to bypass the equivalent output module 303. The auxiliary power supply 102 stops charging the energy storage element 3031. At the same time, the energy storage element 3031 discharges through the control module 302 to discharge all the stored electrical energy of the energy storage element 3031, thereby resetting the equivalent output module 303. Without outputting the detection result, it can also prepare for the equivalent output module 303 to output the detection signal when the drive signal is converted into the first signal.

[0060] Furthermore, during the process of the auxiliary power supply 102 charging the energy storage element 3031, the voltage of the energy storage element 3031 will rise. Then, the equivalent output module 303 will control the unidirectional conduction module 301 to conduct when the voltage of the energy storage element 3031 is greater than the sum of the voltage of the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. That is to say, as the voltage of the energy storage element 3031 rises, the unidirectional conduction module 301 can conduct only when the voltage of the energy storage element 3031 is greater than the sum of the voltage of the sampling terminal 101 and the conduction voltage drop.

[0061] Then, the voltage of the energy storage element 3031 is clamped. Optionally, the voltage of the energy storage element 3031 is clamped to the sum of the voltage of the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. In this way, the equivalent output module 303 can determine the current detection result according to the voltage of the energy storage element 3031. Optionally, the equivalent output module 303 can determine the voltage of the sampling terminal 101 according to the difference between the voltage of the energy storage element 3031 and the conduction voltage drop, that is, the current detection result can be correspondingly determined.

[0062] In the above embodiments, the equivalent output module 303 includes a storage element 3031. Both the control module 302 and the storage element 3031 are connected to the auxiliary power supply 102. Since the control module 302 can be in a cut-off state when the drive signal is the first signal to control the conduction of the first path between the auxiliary power supply 102 and the storage element 3031, enabling the storage element 3031 to be charged through the auxiliary power supply 102, and can be in a conducting state when the drive signal is the second signal to control the conduction of the second path between the auxiliary power supply 102 and the control module 302, stopping the auxiliary power supply 102 from charging the storage element 3031. Therefore, when the voltage of the storage element 3031 is greater than the sum of the voltage of the sampling terminal 101 and the conduction voltage drop, the equivalent output module 303 can control the unidirectional conduction module 301 to conduct and clamp the voltage of the storage element 3031. In this way, when the equivalent output module 303 operates, a relatively accurate current detection result can be determined according to the voltage of the storage element 3031.

[0063] Figure 5 is a schematic diagram of another current detection circuit in an embodiment, as Figure 5 shown. In an exemplary embodiment, optionally, the control module 302 includes a first transistor Q2. Exemplarily, the first transistor Q2 can be a PNP type triode.

[0064] Among them, the emitter of the first transistor Q2 is respectively connected to the unidirectional conduction module 301 and the first end of the storage element 3031. The base of the first transistor Q2 is used to receive the drive signal. The first end of the storage element 3031 is also connected to the auxiliary power supply 102. The collector of the first transistor Q2 and the second end of the storage element 3031 are both connected to the first ground terminal GND_P2. In Figure 5 , the auxiliary power supply 102 is denoted as VCC_DR, and the drive signal is denoted as PWM.

[0065] Optionally, the voltage of the auxiliary power supply 102 is less than or equal to the voltage corresponding to the first signal. Further optionally, the auxiliary power supply 102 can be the power supply for the drive signal PWM. Please refer to Figure 5 . The voltage of the first signal is equal to the voltage of VCC_DR. Therefore, when the drive signal PWM is the first signal, the voltage between the base and the emitter of the first transistor Q2 is equal, and the first transistor Q2 is in a cut-off state, causing the control module 302 to be in a cut-off state.

[0066] When the driving signal is the second signal, the voltage of the energy storage element 3031 flows through the base of the first transistor Q2 to the driving signal PWM. The voltage at the emitter of the first transistor Q2 is greater than the voltage at the base of the first transistor Q2, and the first transistor Q2 is in the conducting state, so that the control module 302 is in the conducting state.

[0067] In the above embodiment, the control module 302 includes a first transistor Q2. Since the emitter of the first transistor Q2 is respectively connected to the unidirectional conduction module 301 and the first end of the energy storage element 3031, the base of the first transistor Q2 is used to receive the driving signal, and the first end of the energy storage element 3031 is also connected to the auxiliary power supply 102. The collector of the first transistor Q2 and the second end of the energy storage element 3031 are both connected to the first ground terminal GND_P2. Therefore, the state of the control module 302 can be efficiently controlled through the driving signal.

[0068] Please continue to refer to Figure 5 In an exemplary embodiment, optionally, the unidirectional conduction module 301 includes a first diode D3. Exemplarily, the first diode D3 can be a Schott diode. Wherein, the positive electrode of the first diode D3 is connected to the equivalent output module 303, and the negative electrode of the first diode D3 is connected to the sampling terminal 101.

[0069] Further optionally, the positive electrode of the first diode D3 is respectively connected to the emitter of the first transistor Q2 and the first end of the energy storage element 3031, and the negative electrode of the first diode D3 is connected to the sampling terminal 101.

[0070] Please refer to Figure 5 When the driving signal changes to the first signal, due to the existence of the unidirectional conduction module 301, the equivalent output module 303 does not start working immediately. Instead, when the voltage of the energy storage element 3031 is greater than the sum of the voltage of the sampling terminal 101 and the conduction voltage drop, the unidirectional conduction module 301 will conduct, so that the equivalent output module 303 determines the current detection result, which can reduce the surge spikes at the moment of switching to the first signal or the second signal due to parasitic parameters.

[0071] In the above embodiment, the unidirectional conduction module 301 includes a first diode D3. Since the positive electrode of the first diode D3 is connected to the equivalent output module 303 and the negative electrode of the first diode D3 is connected to the sampling terminal 101, the first diode D3 can not only play a role in unidirectional conduction, but also reduce the surge spikes when the flyback circuit 100 is turned on or off.

[0072] Figure 6 Schematic diagram of another current detection circuit in an embodiment, as Figure 6As shown, in an exemplary embodiment, optionally, the current detection circuit 300 further includes a compensation module 304. Among them, the compensation module 304 is connected to the equivalent output module 303, and the conduction voltage drop of the compensation module 304 is the same as that of the unidirectional conduction module 301. Further optionally, the compensation module 304 and the unidirectional conduction module 301 can be symmetrically arranged at both ends of the equivalent output module 303.

[0073] The equivalent output module 303 is configured to, during operation, determine the output voltage in response to the voltage at the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. Optionally, the output voltage of the equivalent output module 303 is equal to the sum of the voltage at the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. Further optionally, the output voltage of the equivalent output module 303 can be the voltage of the energy storage element 3031.

[0074] The compensation module 304 is configured to compensate the output voltage of the equivalent output module 303 according to the conduction voltage drop of the compensation module 304 to obtain a compensation voltage. Optionally, the compensation voltage is equal to the output voltage of the equivalent output module 303 minus the conduction voltage drop of the unidirectional conduction module 301.

[0075] Furthermore, the compensation module 304 can determine the current detection result based on the compensation voltage. Exemplarily, the compensation module 304 can equivalent the compensation voltage to the voltage at the sampling terminal 101, that is, it can be correspondingly equivalent to the current detection result.

[0076] It can be understood that when the equivalent output module 303 is not operating, both the current detection result and the compensation voltage can be default preset values, such as 0.

[0077] In the above embodiment, the current detection circuit 300 further includes a compensation module 304. Since the compensation module 304 is connected to the equivalent output module 303 and the conduction voltage drop of the compensation module 304 is the same as that of the unidirectional conduction module 301, therefore, when the equivalent output module 303 is operating, it can determine the output voltage in response to the voltage at the sampling terminal 101 and the conduction voltage drop of the unidirectional conduction module 301. Furthermore, after the compensation module 304 compensates the output voltage of the equivalent output module 303 through its own conduction voltage drop to obtain a compensation voltage, it can determine the relatively accurate voltage at the sampling terminal 101 based on the compensation voltage, that is, it can be correspondingly equivalent to the current detection result.

[0078] Please continue to refer to Figure 5 , in an exemplary embodiment, optionally, the compensation module 304 includes a second diode D4. Among them, the positive electrode of the second diode D4 is connected to the equivalent output module 303, and the negative electrode of the second diode D4 is connected to the output terminal of the current detection circuit 300.

[0079] In the above embodiments, since the compensation module 304 includes the second diode D4, and the positive electrode of the second diode D4 is connected to the equivalent output module 303, and the negative electrode of the second diode D4 is connected to the output terminal of the current detection circuit 300, therefore, the compensation voltage can be determined according to the difference between the output voltage of the equivalent output module 303 and the conduction voltage drop of the unidirectional conduction module 301. In this way, the conduction voltage drop generated by the guiding conduction module can be compensated through the compensation voltage, and a relatively accurate compensation voltage can be obtained. Schematically, the second diode D4 and the first diode D3 are selected as diodes with the same specifications and parameters to ensure that under different environmental conditions, the second diode D4 compensates and cancels the voltage drop of the first diode D3, so that the voltage of the equivalent output module 303 is the current detection result.

[0080] Figure 7 Schematic diagram of another current detection circuit in an embodiment, as Figure 7 shown, in an exemplary embodiment, optionally, the current detection circuit 300 further includes an operation module 305. Among them, the operation module 305 is connected to the equivalent output module 303.

[0081] The operation module 305 is used to determine the current detection result according to the output voltage of the equivalent output module 303. Optionally, the operation module 305 can use a differential operation circuit to perform proportional operation on the output voltage of the equivalent output module 303 to determine the current detection result.

[0082] Exemplarily, please refer to Figure 5 , the operation module 305 may include a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C4, an operational amplifier U1B, a capacitor C5, a resistor R12, a resistor R13, and a capacitor C6.

[0083] Please refer to Figure 5 , in an embodiment, the output voltage of the equivalent output module 303 is expressed as V - I0. V - I0 is divided by the resistors R7 and R8 to obtain the input voltage V_I1 required to match the subsequent operation circuit. After the operation module 305 performs proportional operation on the input voltage V_I1, the operation result can be sent to the subsequent microcontroller unit (MCU) for sampling by the analog - to - digital converter (ADC).

[0084] It can be understood that Figure 5 only one optional way of the operation module 305 is exemplified. In some embodiments, the operation module 305 can also be implemented by a processor or other logic units, and this embodiment is not limited thereto.

[0085] In some embodiments, please refer to Figure 6 , if the current detection circuit 300 includes a compensation module 304 and an operation module 305, the compensation module 304 is respectively connected to the equivalent output module 303 and the operation module 305. The operation module 305 is configured to determine the current detection result according to the compensation voltage output by the compensation module 304.

[0086] In the above embodiments, since the current detection circuit 300 further includes an operation module 305, and the operation module 305 is connected to the equivalent output module 303, therefore, through the operation module 305, the current detection result can be efficiently and accurately determined according to the output voltage of the equivalent output module 303.

[0087] Please continue to refer to Figure 5 , in an exemplary embodiment, optionally, the current detection circuit 300 further includes a pull-up current-limiting resistor R6, and the pull-up current-limiting resistor R6 is disposed between the auxiliary power supply 102 and the equivalent output module 303. The sampling terminal 101 includes a sampling resistor R4. The first end of the sampling resistor R4 is respectively connected to the emitter of the power transistor Q1 and the unidirectional conduction module 301, and the second end of the sampling resistor R4 is connected to the second ground terminal GND_POWER. Moreover, the resistance value of the pull-up current-limiting resistor R6 is greater than that of the sampling resistor R4. Exemplarily, the resistance value of the pull-up current-limiting resistor R6 can be dozens or hundreds of times that of the sampling resistor R4, and this embodiment is not limited thereto.

[0088] In the above embodiments, since the resistance value of the pull-up current-limiting resistor R6 is greater than that of the sampling resistor R4, therefore, the output voltage of the equivalent output module 303 can be reliably clamped to the sum of the conduction voltage drop and the voltage of the sampling terminal 101.

[0089] In an exemplary embodiment, optionally, the second ground terminal GND_POWER is the power ground terminal of the flyback circuit 100, and the first ground terminal GND_P2 corresponding to the equivalent output module 303 is connected to the second ground terminal GND_POWER through a bus capacitor.

[0090] Please continue to refer to Figure 5 , GND_POWER is the power ground of the flyback circuit 100, and GND_P2 is connected to GND_POWER at the bus capacitor, which can avoid the interference to the signal ground GND_P2 when the flyback circuit works in the loop, reduce the influence of the surge spikes at the moment of turn-on and turn-off of the flyback circuit 100 on the current detection result, and achieve more reliable current detection.

[0091] In the above embodiments, since the second grounding terminal GND_POWER is the power grounding terminal of the flyback circuit 100, and the first grounding terminal GND_P2 corresponding to the equivalent output module 303 is connected to the second grounding terminal GND_POWER through a bus capacitor, therefore, through this grounding method, the reliability and accuracy of current detection can be further improved.

[0092] To more clearly introduce the current detection circuit of the present application, an example is given here in combination with Figure 5 , where the energy storage element 3031 includes a capacitor C3. As Figure 5 shown, when the driving signal PWM of the power transistor Q1 in the flyback circuit 100 is a high-level signal, the power transistor Q1 is in the conducting state, and BUS+ flows through the primary winding of the transformer T1, the power transistor Q1, the sampling resistor R4, and the parasitic inductances Lr1 and Lr2 of the PCB to the second grounding terminal GND_POWER. The current of the sampling resistor R4 is equal to the winding current IP of the primary winding. VCC_DR is the power supply for the driving signal PWM, and the voltage of the driving signal PWM is equal to the voltage of VCC_DR when it is at a high level.

[0093] On the one hand, when the driving signal PWM is at a high level, the first transistor Q2 is cut off, and VCC_DR charges the capacitor C3 through the resistor R6. When the voltage V-I0 of C3 is greater than the sum of the voltages of the first diode D3 and the sampling resistor R4, the first diode D3 conducts.

[0094] Moreover, the resistance value of the resistor R6 is much larger than the resistance value of the sampling resistor R4, and the voltage of V-I0 is clamped to the sum of the conduction voltage drop of the first diode D3 and the voltage of the sampling resistor R4. As the power transistor Q1 continues to conduct, the winding current IP continues to increase, the voltage of the sampling resistor R4 also continues to increase, and the voltage of V-I0 also continues to increase. That is to say, the voltage of V-I0 can follow the voltage of the sampling resistor R4.

[0095] Furthermore, the operation module 305 can use a differential operation circuit to perform proportional operation on V_I1, and send the result of the proportional operation to the MCU for ADC sampling.

[0096] Among them, the types of the first diode D3 and the second diode D4 can be the same. In this way, even when the circuit works in various temperature environments, the conduction voltage drops of both are equal. Through the second diode D4, the compensation voltage V-I1 can accurately follow the voltage across the sampling resistor R4.

[0097] The first diode D3 plays an isolation role in the current detection circuit. The first diode D3 is reversely connected to the sampling resistor R4 and can be a Schottky diode. The response time of the Schottky diode is at the nanosecond level. When surge spikes are generated at the moment of turning on and off the power transistor Q1, it can block the reverse injection of the surge spikes into the capacitor C3, so that V_I0 is not interfered by the surge spikes when the power transistor Q1 is turned on and off.

[0098] On the other hand, when the driving signal PWM of the power transistor Q1 is a low-level signal, BUS+ cannot form a current loop through the primary winding of the transformer T1, the winding current IP of the primary winding is zero, no current flows through the sampling resistor R4, and the voltage of the sampling resistor R4 is zero.

[0099] Moreover, since the driving signal PWM is at a low level, V_I0 flows through the base of the first transistor Q2 and the resistor R5 to the driving signal PWM, causing the first transistor Q2 to conduct, and the V_I0 voltage is pulled to GND_P2. In this way, V_I0 is equal to 0 when PWM is at a low level and can also follow the voltage of the sampling resistor R4.

[0100] Among them, by connecting GND_P2 to GND_POWER at the bus capacitor, the influence of the surge spikes at the moment of turning on and off the flyback circuit on V_I0 and V_I1 is reduced, making the current detection circuit more reliable.

[0101] To sum up, since the current detection circuit provided by this application uses discrete devices, combines the working principle of the flyback circuit, borrows the driving signal of the power transistor in the flyback circuit, and stops working when the driving signal PWM is at a low level, it has high reliability. Not only is the circuit cost low and the layout simple, but it also cleverly and accurately realizes the detection function of the winding current in the high-frequency chopper, reducing the influence of the parasitic parameters in the flyback circuit on the current detection result. And. This circuit uses a small-current first diode D3 to isolate the main power circuit and the low-voltage circuit, and uses a second diode D4 with the same small current for compensation, so that the current detection circuit can still work reliably in various temperature environments. Therefore, finally, an ideal current detection result as shown in Figure 2 Figure (a) in can be obtained.

[0102] Figure 8 It is a schematic diagram of an energy storage power supply in an embodiment. In an embodiment, as shown in Figure 8 shown, an energy storage power supply 800 is further provided. The energy storage power supply 800 includes a flyback circuit 100 and a current detection circuit 300 as described in any one of the above.

[0103] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in this application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0104] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded in this application.

[0105] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A current detection circuit applied to a flyback circuit, characterized in that The current detection circuit includes a one-way conduction module, a control module, and an equivalent output module connected in sequence. The one-way conduction module is connected to the sampling terminal of the flyback circuit. The equivalent output module is respectively connected to the one-way conduction module and the control module. The control module is further configured to receive a driving signal, and the driving signal is used to control the working state of the flyback circuit; The control module is configured to control the equivalent output module to work when the driving signal is a first signal, and to control the equivalent output module to stop working when the driving signal is a second signal, where the first signal is a driving signal for driving the power transistor of the flyback circuit to conduct, and the second signal is a driving signal for driving the power transistor to cut off; The equivalent output module is configured to, when working, determine the current detection result of the flyback circuit in response to the voltage at the sampling terminal of the flyback circuit and the conduction voltage drop of the one-way conduction module.

2. The current detection circuit according to claim 1, wherein The equivalent output module includes an energy storage element; both the control module and the energy storage element are connected to an auxiliary power supply; The control module is configured to be in a cut-off state when the driving signal is the first signal to control the first path between the auxiliary power supply and the energy storage element to conduct, so that the energy storage element is charged through the auxiliary power supply; and to be in a conducting state when the driving signal is the second signal to control the second path between the auxiliary power supply and the control module to conduct, so that the auxiliary power supply stops charging the energy storage element; The equivalent output module is configured to, when the voltage of the energy storage element is greater than the sum of the voltage at the sampling terminal and the conduction voltage drop, control the one-way conduction module to conduct and clamp the voltage of the energy storage element, so as to determine the current detection result according to the voltage of the energy storage element.

3. The current detection circuit according to claim 2, characterized in that, The control module includes a first transistor; the emitter of the first transistor is respectively connected to the one-way conduction module and the first end of the energy storage element. The base of the first transistor is configured to receive the driving signal. The first end of the energy storage element is also connected to the auxiliary power supply. The collector of the first transistor and the second end of the energy storage element are both connected to a first ground terminal.

4. The current detection circuit according to claim 1, characterized in that, The one-way conduction module includes a first diode; the positive electrode of the first diode is connected to the equivalent output module, and the negative electrode of the first diode is connected to the sampling terminal.

5. The current detection circuit according to any one of claims 1-3, characterized in that, The current detection circuit further includes a compensation module. The compensation module is connected to the equivalent output module, and the conduction voltage drop of the compensation module is the same as that of the one-way conduction module; The equivalent output module is configured to, when working, determine the output voltage in response to the voltage at the sampling terminal and the conduction voltage drop of the one-way conduction module; The compensation module is configured to compensate the output voltage of the equivalent output module according to the conduction voltage drop of the compensation module to obtain a compensation voltage, and determine the current detection result according to the compensation voltage.

6. The current detection circuit according to claim 5, characterized in that, The compensation module includes a second diode; the positive electrode of the second diode is connected to the equivalent output module, and the negative electrode of the second diode is connected to the output end of the current detection circuit.

7. The current detection circuit according to any one of claims 1-3, characterized in that, The current detection circuit further includes an operation module, and the operation module is connected to the equivalent output module; The operation module is configured to determine the current detection result according to the output voltage of the equivalent output module.

8. The current detection circuit according to any one of claims 1-3, characterized in that, The current detection circuit further includes a pull-up current-limiting resistor, and the pull-up current-limiting resistor is arranged between the auxiliary power supply and the equivalent output module; The sampling terminal includes a sampling resistor, the first end of the sampling resistor is respectively connected to the emitter of the power transistor and the unidirectional conduction module, and the second end of the sampling resistor is connected to a second grounding terminal; The resistance value of the pull-up current-limiting resistor is greater than the resistance value of the sampling resistor.

9. The current detection circuit according to claim 8, wherein, The second grounding terminal is the power grounding terminal of the flyback circuit, and the first grounding terminal corresponding to the equivalent output module is connected to the second grounding terminal through a bus capacitor.

10. A energy storage power supply, characterized in that, The energy storage power supply includes a flyback circuit and the current detection circuit according to any one of claims 1-9.

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