Buck-boost circuit and current detection circuit thereof

Abstract

The invention relates to a buck-boost circuit and a current detection circuit thereof. The current detection circuit comprises a first current detection module and a second current detection module. The first current detection module is connected with a boost control switch of the buck-boost circuit; the second current detection module is connected with a step-down control switch of the step-up and step-down circuit; in a boost mode, the first current detection module collects a first current in a current rising stage, and the second current detection module collects a second current in a current falling stage; in a voltage reduction mode, the first current detection module collects first current in a current reduction stage, and the second current detection module collects second current in a current rise stage; the sampling output end of the first current detection module and the sampling output end of the second current detection module are connected to the total output end. The first current detection module and the second current detection module are used for sampling the current of the buck-boost circuit in different modes and different branches, and current detection of the buck-boost circuit is achieved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of buck-boost circuits, and in particular, to a buck-boost circuit and its current detection circuit. Background Art

[0002] With the rapid development of power electronic products such as switching power supplies, uninterruptible power supplies, and energy storage inverters, the buck-boost circuit (BUCK-BOOST circuit) has been widely used. If the current output by the buck-boost circuit in a power electronic product is too large, it will cause damage to the components inside the product. Therefore, it is necessary to effectively detect the current output of the buck-boost circuit to achieve overcurrent protection for the power electronic product. Thus, how to implement current detection for the buck-boost circuit has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0003] In order to solve the above technical problem or at least partially solve the above technical problem, the present disclosure provides a buck-boost circuit and its current detection circuit.

[0004] In a first aspect, the present disclosure provides a current detection circuit for a buck-boost circuit, including: a first current detection module and a second current detection module;

[0005] The first current detection module is connected to the boost control switch of the buck-boost circuit;

[0006] The second current detection module is connected to the buck control switch of the buck-boost circuit;

[0007] In the boost mode of the buck-boost circuit, the first current detection module is used to collect a first current in the current rising stage, and the second current detection module is used to collect a second current in the current falling stage;

[0008] In the buck mode of the buck-boost circuit, the first current detection module is used to collect a first current in the current falling stage, and the second current detection module is used to collect a second current in the current rising stage;

[0009] The sampling output terminal of the first current detection module and the sampling output terminal of the second current detection module are connected to a total output terminal;

[0010] Wherein, the total output terminal is used to output the detection current of the current detection circuit; the detection current is used to implement current detection for the buck-boost circuit.

[0011] In a second aspect, the present disclosure further provides a buck-boost circuit, and the buck-boost circuit is connected to the current detection circuit provided in the first aspect;

[0012] The buck-boost circuit includes: a boost control switch, a buck control switch, a first inductor, a first capacitor, and a second capacitor;

[0013] The low - voltage end of the buck - boost circuit is connected to the first end of the first inductor. The second end of the first inductor is connected to the first end of the boost control switch and the first end of the buck control switch. The second end of the boost control switch is grounded. The second end of the buck control switch is connected to the high - voltage end of the buck - boost circuit. The first end of the first inductor is grounded through the first capacitor. The second end of the buck control switch is grounded through the second capacitor.

[0014] The present disclosure provides a buck - boost circuit and its current detection circuit. The current detection circuit includes a first current detection module and a second current detection module. The first current detection module is connected in series with the boost control switch of the buck - boost circuit, and the second current detection module is connected in series with the buck control switch of the buck - boost circuit.

[0015] In the boost mode of the buck - boost circuit, the conduction and disconnection of the boost control switch alternate, and the buck control switch remains in the off state. When the boost control switch is conducting, the first current detection module collects the first current in the current rising stage and outputs it through the total output terminal, and the second current detection module does not collect current. When the boost control switch is disconnected, the first current detection module does not collect current, and the second current detection module collects the second current in the current falling stage and outputs it through the total output terminal.

[0016] In the buck mode of the buck - boost circuit, the conduction and disconnection of the buck control switch alternate, and the boost control switch remains in the off state. When the buck control switch is conducting, the second current detection module collects the second current in the current rising stage and outputs it through the total output terminal, and the first current detection module does not collect current. When the buck control switch is disconnected, the second current detection module does not collect current, and the first current detection module collects the first current in the current falling stage and outputs it through the total output terminal.

[0017] The total output terminal finally outputs the detection current of the current detection circuit, and the detection current is used to implement over - current protection for the buck - boost circuit. Thus, the present disclosure realizes that in both the boost mode and the buck mode of the buck - boost circuit, the current of the entire buck - boost circuit can be sampled and detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 FIG. 22 is a schematic structural diagram of a buck - boost circuit provided by the related art.

[0020] Figure 2 Schematic diagram of the current detection circuit of a buck-boost circuit provided by an embodiment of the present disclosure.

[0021] Figure 3 Schematic diagram of the current output at the total output terminal of a current detection circuit in boost mode provided by an embodiment of the present disclosure.

[0022] Figure 4 Schematic diagram of the current output at the total output terminal of a current detection circuit in buck mode provided by an embodiment of the present disclosure.

[0023] Figure 5 Schematic diagram of the current detection circuit of another buck-boost circuit provided by an embodiment of the present disclosure.

[0024] Figure 6 Circuit diagram of a first current detection module provided by an embodiment of the present disclosure.

[0025] Figure 7 Schematic diagram of the current detection circuit of another buck-boost circuit provided by an embodiment of the present disclosure.

[0026] Figure 8 Circuit diagram of a second current detection module provided by an embodiment of the present disclosure.

[0027] Figure 9 Schematic diagram of the current detection circuit of another buck-boost circuit provided by an embodiment of the present disclosure.

[0028] Figure 10 Schematic diagram of the structure of a buck-boost circuit provided by an embodiment of the present disclosure. Detailed implementation manners

[0029] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present application by showing examples of the present application.

[0030] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The embodiments will be described in detail below with reference to the drawings.

[0031] Figure 1 Schematic diagram of the structure of a buck-boost circuit provided for the related art, as Figure 1 shown, the buck-boost circuit includes a boost control switch 110, a buck control switch 120, a first inductor L1, a first capacitor C1, and a second capacitor C2.

[0032] The low-voltage terminal 101 of the buck-boost circuit is connected to the first end of the first inductor L1. The second end of the first inductor L1 is connected to the first end of the boost control switch 110 and the first end of the buck control switch 120. The second end of the boost control switch 110 is grounded. The second end of the buck control switch 120 is connected to the high-voltage terminal 102 of the buck-boost circuit. The first end of the first inductor L1 is grounded through the first capacitor C1. The second end of the buck control switch 120 is grounded through the second capacitor C2.

[0033] In the boost mode of the buck-boost circuit, the current direction in the buck-boost circuit is from the low-voltage terminal 101 of the buck-boost circuit to the high-voltage terminal 102 of the buck-boost circuit. The boost control switch 110 will alternately conduct and disconnect according to the PWM wave (Pulse Width Modulation wave) received at the control terminal. When the boost control switch 110 conducts, the voltage across the first inductor L1 gradually increases, thereby causing the current in the branch where the boost control switch 110 is located to gradually increase. When the boost control switch 110 disconnects, the first inductor L1 discharges through the body diode of the buck control switch 120, thereby causing the current in the branch where the buck control switch 120 is located to gradually increase.

[0034] In the buck mode of the buck-boost circuit, the current direction in the buck-boost circuit is from the high-voltage terminal 102 of the buck-boost circuit to the low-voltage terminal 101 of the buck-boost circuit. The buck control switch 120 will alternately conduct and disconnect according to the PWM wave received at the control terminal. When the buck control switch 120 conducts, the voltage across the first inductor L1 gradually increases, thereby causing the current in the branch where the buck control switch 120 is located to gradually increase. When the buck control switch 120 disconnects, the first inductor L1 discharges through the body diode of the boost control switch 110, thereby causing the current in the branch where the boost control switch 110 is located to gradually increase.

[0035] With the rapid development of power electronic products such as switching power supplies, uninterruptible power supplies, and energy storage inverters, buck-boost circuits have been widely used. If the current output by the buck-boost circuit in a power electronic product is too large, it will cause damage to the components inside the product. Therefore, it is necessary to effectively detect the current output situation of the buck-boost circuit to achieve overcurrent protection for power electronic products.

[0036] In the related art, a current Hall sensor is usually used to detect the current of a buck-boost circuit. However, the price of the current Hall sensor is relatively expensive, and the current Hall sensor is also easily affected by environmental factors such as temperature and external magnetic fields. Therefore, in order to reduce the influence of environmental factors, the cost of current detection will undoubtedly be greatly increased, which is not conducive to large-scale applications. In addition, when measuring large currents, the Hall sensor may exhibit non-linear errors, affecting the measurement accuracy. At this time, special calibration and compensation methods need to be used to reduce the non-linear errors, increasing the complexity of the current detection process.

[0037] Therefore, how to achieve current detection of the buck-boost circuit and reduce the cost of current detection has become a technical problem that needs to be solved urgently by those skilled in the art.

[0038] To solve the above technical problems, the embodiments of the present application provide a buck-boost circuit and its current detection circuit. First, the current detection circuit of the buck-boost circuit provided by the embodiments of the present application will be introduced below.

[0039] Figure 2 FIG. is a schematic structural diagram of a current detection circuit of a buck-boost circuit provided by an embodiment of the present disclosure. The current detection circuit is used to be connected to the buck-boost circuit to realize current detection of the buck-boost circuit. As Figure 2 shown, the current detection circuit includes a first current detection module 200 and a second current detection module 300.

[0040] The first current detection module 200 is connected to the boost control switch 110 of the buck-boost circuit; the second current detection module 300 is connected to the buck control switch 120 of the buck-boost circuit.

[0041] Exemplarily, the boost control switch 110 and the buck control switch 120 may be semiconductor switch devices such as MOS transistors and triodes.

[0042] In the boost mode of the buck-boost circuit, the first current detection module 200 is used to collect a first current in the current rising stage, and the second current detection module 300 is used to collect a second current in the current falling stage.

[0043] Specifically, in the boost mode of the buck-boost circuit, the boost control switch 110 will alternately conduct and disconnect according to the PWM wave received at the control terminal, and the buck control switch 120 remains in the off state. When the boost control switch 110 conducts, the first current detection module 200 will collect the first current in the current rising stage, and the second current detection module 300 does not collect any current. When the boost control switch 110 disconnects, the inductor will impede the current reduction due to self-inductance, causing the inductor current to gradually decrease. At this time, it is in the current falling stage, the first current detection module 200 does not collect any current, and the second current detection module 300 collects the second current in the current falling stage.

[0044] In the buck mode of the buck-boost circuit, the first current detection module 200 is used to collect the first current in the current falling stage, and the second current detection module 300 is used to collect the second current in the current rising stage.

[0045] Specifically, in the buck mode of the buck-boost circuit, the buck control switch 120 will alternately conduct and disconnect according to the PWM wave received at the control terminal, and the boost control switch 110 remains in the off state. When the buck control switch 120 conducts, the second current detection module 300 will collect the second current in the current rising stage, and the first current detection module 200 does not collect any current. When the buck control switch 120 disconnects, the inductor current gradually decreases. At this time, the second current detection module 300 does not collect any current, and the first current detection module 200 collects the first current in the current falling stage.

[0046] The sampling output terminal of the first current detection module 200 and the sampling output terminal of the second current detection module 100 are connected to the total output terminal 400; among them, the total output terminal 400 is used to output the detection current of the current detection circuit; the detection current is used to implement the current detection of the buck-boost circuit.

[0047] Specifically, since a voltage drop is generated when current passes through a resistor, the magnitude of the current in the circuit where the resistor is located can be measured by detecting the voltage drop across the resistor. Therefore, in related technologies, usually a resistor and a voltage detection module for detecting the voltage across the resistor are added to the buck-boost circuit as the current detection circuit of the buck-boost circuit, so as to realize the detection of the current in the buck-boost circuit. However, since the current flow direction in the buck-boost circuit changes under different operating modes. For example, in a typical buck-boost circuit, if the current detection circuit does not take into account the change in the current direction, it may cause the current value detected by the current detection circuit to be a positive current in the boost mode, or a negative current in the buck mode, thus affecting the accuracy of current detection. In the boost mode and the buck mode of the buck-boost circuit of the present disclosure, the first current detection module 200 only detects the current in the branch where the boost control switch 110 is located, and the second current detection module 300 only detects the current in the branch where the buck control switch 120 is located, so that only one current detection module corresponds to one control switch for current detection. Therefore, no matter how the current flow direction changes, the result of current detection will not change, thus avoiding the problem of inaccurate detection caused by the change in the current flow direction.

[0048] Figure 3 The schematic diagram of the current output by the total output terminal of a current detection circuit provided by an embodiment of the present disclosure in the boost mode is shown as Figure 3 shown. In the boost mode, when the boost control switch 110 is turned on, the total output terminal 400 outputs a first current in the rising stage during the time period t1, and when the boost control switch 110 is turned off, the total output terminal 400 outputs a second current in the falling stage during the time period t2. Thus, by detecting the detected current output by the total output terminal 400, the current detection of the buck-boost circuit can be realized in the boost mode of the buck-boost circuit.

[0049] Figure 4 The schematic diagram of the current output by the total output terminal of a current detection circuit provided by an embodiment of the present disclosure in the buck mode is shown as Figure 4 shown. In the buck mode, when the buck control switch 120 is turned on, the total output terminal 400 outputs a second current in the rising stage during the time period t3, and when the buck control switch 120 is turned off, the total output terminal 400 outputs a first current in the falling stage during the time period t4. Thus, by detecting the detected current output by the total output terminal 400, the current detection of the buck-boost circuit can be realized in the buck mode of the buck-boost circuit. Moreover, the present disclosure does not need to use a current Hall sensor, but uses the first current detection module 200 and the second current detection module 230 with a simple circuit structure for current detection. Therefore, the cost of current detection is low.

[0050] In some embodiments, Figure 5 FIG. 3 is a schematic structural diagram of a current detection circuit of another buck-boost circuit provided by an embodiment of the present disclosure. As Figure 5 shown, the first current detection module includes: a first sampling unit 210 and a first amplification unit 220.

[0051] The first sampling unit 210 is connected in series with the boost control switch 110. The first sampling unit 210 is configured to collect a first current and convert the first current into a first voltage. The input end of the first amplification unit 220 is connected to the first sampling unit 210, and the output end of the first amplification unit 220 is connected to the total output end 400. The first amplification unit 220 is configured to amplify the first voltage.

[0052] Specifically, in the boost mode of the buck-boost circuit, when the boost control switch 110 is turned on, the first sampling unit 210 collects the first current in the current rising stage and converts the first current into a first voltage and outputs it to the input end of the first amplification unit 220. In the buck mode of the buck-boost circuit, when the buck control switch is turned off, the first sampling unit 210 collects the first current in the current falling stage and converts the first current into a first voltage and outputs it to the input end of the first amplification unit 220. After the first amplification unit 220 amplifies the received first voltage according to the set gain, it is then converted into a voltage through a current limiting resistor provided in the first current detection module and output to the total output end 400. Thus, by collecting the voltage at the total output end 400, the current flowing through the boost control switch 110 when the boost control switch 110 is turned on in the buck-boost circuit can be obtained, and the current flowing through the body diode of the boost control switch 110 when the buck control switch is turned off in the buck-boost circuit can be obtained.

[0053] In some embodiments, Figure 6 FIG. 4 is a circuit diagram of a first current detection module provided by an embodiment of the present disclosure. As Figure 6 shown, the first sampling unit includes: a first current transformer U1 and a first sampling resistor R1.

[0054] Exemplarily, the first sampling unit may further include a plurality of sampling resistors. The plurality of sampling resistors and the first sampling resistor R1 may be connected in series, in parallel, or in a combination of series and parallel connections, which is not limited herein.

[0055] The main coil of the first current transformer U1 is connected in series with the boost control switch 110. The first output terminal of the secondary coil of the first current transformer U1 is connected to the first end of the first sampling resistor R1 and the first input terminal of the first amplification unit. The second output terminal of the secondary coil of the first current transformer U1 is connected to the second end of the first sampling resistor R1 and the second input terminal of the first amplification unit. The first current transformer U1 is used to convert the first current into a first sampling current, and the first sampling resistor R1 is used to convert the first sampling current into a first voltage.

[0056] Exemplarily, the first amplification unit includes a first operational amplifier U2 and a first current-limiting resistor R2. The non-inverting input terminal of the first operational amplifier U2 is connected to the first output terminal of the secondary coil of the first current transformer U1. The inverting input terminal of the first operational amplifier U2 is connected to the second output terminal of the secondary coil of the first current transformer U1. The output terminal of the first operational amplifier U2 is connected to the total output terminal 400 through the first current-limiting resistor R2.

[0057] The first current transformer U1 converts the current flowing through the boost control switch 110 collected by the main coil into the first sampling current of the secondary coil, so as to realize the current acquisition when the boost control switch 110 is turned on in the boost mode of the buck-boost circuit. And it realizes the current acquisition of the body diode of the boost control switch 110 when the buck control switch is turned off in the buck mode of the buck-boost circuit. The first sampling resistor R1 converts the received first sampling current into a first voltage and outputs it to the first operational amplifier U2. The first operational amplifier U2 amplifies the received first voltage according to the set gain. The amplification gain of the first operational amplifier U2 can be adjusted by the gain resistors (not shown in the figure) arranged at the non-inverting input terminal and the inverting input terminal. After amplifying the first voltage, it is output to the total output terminal 400. Thus, by collecting the voltage of the total output terminal 400, the current flowing through the boost control switch 110 when the boost control switch 110 is turned on in the boost mode of the buck-boost circuit can be obtained. And the current of the body diode of the boost control switch 110 when the buck control switch is turned off in the buck mode. The present disclosure can more accurately reflect the current waveform in the buck-boost circuit by setting the first current transformer U1 to sample the current, and the amplitude of the finally collected current waveform also corresponds to the output of the first current transformer U1. Therefore, the accuracy and linearity of current detection are improved. And collecting the current by using a current transformer can make the circuit design more concise and reduce the circuit cost at the same time.

[0058] In some embodiments, continue to refer to Figure 6, the first current detection module further includes a first voltage follower U3. The non-inverting input terminal of the first voltage follower U3 is connected to the output terminal of the first amplification unit, and the inverting input terminal of the first voltage follower U3 is connected to the output terminal of the first voltage follower U3; the output terminal of the first voltage follower U3 is connected to the total output terminal 400.

[0059] Exemplarily, the first current detection module further includes a second current-limiting resistor R3, and the output terminal of the first voltage follower U3 is connected to the total output terminal 400 through the second current-limiting resistor R3. The voltage output by the first operational amplifier U2 is output to the total output terminal 400 after passing through the first voltage follower U3, thereby realizing buffering and isolation of the output signal of the first operational amplifier U2, avoiding the interference of the current output by the first operational amplifier U2 by interference signals, and further making the output current more accurate, improving the accuracy of current detection.

[0060] In some embodiments, the first current detection module further includes a first filtering unit; the output terminal of the first voltage follower is grounded through the first filtering unit.

[0061] Specifically, the first filtering unit can filter out the interference signals in the voltage signal output by the first voltage follower, so that the current output to the total output terminal is more accurate, and further improves the accuracy of current detection.

[0062] In some embodiments, continue to refer to Figure 6 , the first current detection module further includes a first diode D1 and a second diode D2.

[0063] The first output terminal of the first current transformer U1 is connected to the positive terminal of the first diode D1, the negative terminal of the first diode D1 is connected to the first input terminal of the first amplification unit, the second output terminal of the first current transformer U1 is connected to the negative terminal of the second diode D2, and the positive terminal of the second diode D2 is connected to the second input terminal of the first amplification unit.

[0064] Exemplarily, the negative terminal of the first diode D1 is connected to the non-inverting input terminal of the first operational amplifier U2, and the positive terminal of the second diode D2 is connected to the inverting input terminal of the first operational amplifier U2. When the boost control switch 110 is turned on, the first diode D1 and the second diode D2 can conduct normally to achieve current acquisition. When the boost control switch 110 is turned off, the demagnetization of the secondary coil of the first current transformer U1 generates an abnormal voltage. At this time, the first diode D1 and the second diode D2 can be reversely cut off, thereby avoiding the abnormal output current of the first current detection module due to the voltage generated by the demagnetization of the secondary coil of the first current transformer U1 when the boost control switch 110 is turned off. Therefore, it is possible to avoid the influence of the first current detection module on the current output by the second current detection module, so that the current output at the total output terminal 400 is more accurate and the current detection accuracy is improved.

[0065] In some embodiments, the first current detection module further includes: a first clamping unit and a second clamping unit; the first end of the first clamping unit is connected to the first input terminal of the first amplifying unit, the second end of the first clamping unit is connected to the second end of the second clamping unit, and the first end of the second clamping unit is connected to the second input terminal of the first amplifying unit.

[0066] Exemplarily, continue to refer to Figure 6 , the first clamping unit may be, for example, the first clamping voltage stabilizing diode D3, and the second clamping unit may be, for example, the second clamping voltage stabilizing diode D4. The negative terminal of the first clamping voltage stabilizing diode D3 is connected to the non-inverting input terminal of the first operational amplifier U2, the positive terminal of the first clamping voltage stabilizing diode D3 is connected to the positive terminal of the second clamping voltage stabilizing diode D4, and the negative terminal of the second clamping voltage stabilizing diode D4 is connected to the inverting input terminal of the first operational amplifier U2. When the boost control switch 110 is turned off, the demagnetization of the secondary coil of the first current transformer U1 may cause an excessively high output voltage. Through the provided first clamping voltage stabilizing diode D3 and the second clamping voltage stabilizing diode D4 in the present disclosure, the voltage is clamped within a safe range, thereby avoiding damage to the components in the subsequent circuit due to excessive voltage.

[0067] It should be noted that the first clamping unit and the second clamping unit may also be circuit elements such as clamping diodes that can achieve the voltage clamping function, and specific limitations are not made here.

[0068] In some embodiments, continue to refer to Figure 6 , the first sampling module further includes: a first filter capacitor C3, a second filter capacitor C4, a third filter capacitor C5, a first filter resistor R4, a second filter resistor R5, a first load resistor R7, a first clamping diode D5, a second clamping diode D6, a third clamping diode D7, and a fourth clamping diode D8.

[0069] The first filtering unit includes a third filtering resistor R6 and a fourth filtering capacitor C6.

[0070] The first end of the first filtering capacitor C3 is connected to the non-inverting input terminal of the first operational amplifier U2, the second end of the first filtering capacitor C3 is connected to the inverting input terminal of the first operational amplifier U2, and the first load resistor R7 is connected in parallel with the first filtering capacitor C3. The non-inverting input terminal of the first operational amplifier U2 is grounded through the second filtering capacitor C4, and the first filtering resistor R4 is connected in parallel with the second filtering capacitor C4. The inverting input terminal of the first operational amplifier U2 is connected to the first end of the third filtering capacitor C5, the second end of the third filtering capacitor C5 is connected to the output terminal of the first operational amplifier U2, and the second filtering resistor R5 is connected in parallel with the third filtering capacitor C5. The output terminal of the first voltage follower U3 is grounded through the second current-limiting resistor R3 and the fourth filtering capacitor C6, and the third filtering resistor R6 is connected in parallel with the fourth filtering capacitor C6.

[0071] Thus, the first filtering capacitor C3, the second filtering capacitor C4, the third filtering capacitor C5, the first filtering resistor R4, and the second filtering resistor R5 can filter out the interference signals in the voltage signal input to the first operational amplifier U2 and the voltage signal output by the first operational amplifier U2. The fourth filtering capacitor C6 and the third filtering resistor R6 can filter out the interference signals in the voltage signal output by the first voltage follower U3, so that the current output to the total output terminal 400 is more accurate, thereby improving the accuracy of current detection.

[0072] The positive terminal of the first clamping diode D5 is connected to the non-inverting input terminal of the first operational amplifier U2, the negative terminal of the first clamping diode D5 is connected to the first power supply terminal VCC, the positive terminal of the second clamping diode D6 is grounded, and the negative terminal of the second clamping diode D6 is connected to the non-inverting input terminal of the first operational amplifier U2. The positive terminal of the third clamping diode D7 is connected to the inverting input terminal of the first operational amplifier U2, the negative terminal of the third clamping diode D7 is connected to the first power supply terminal VCC, the positive terminal of the fourth clamping diode D8 is grounded, and the negative terminal of the fourth clamping diode D8 is connected to the inverting input terminal of the first operational amplifier U2.

[0073] The first clamping diode D5 and the second clamping diode D6 can clamp the voltage input to the non-inverting input terminal of the first operational amplifier U2, and the third clamping diode D7 and the fourth clamping diode D8 can clamp the voltage input to the inverting input terminal of the first operational amplifier U2, thereby realizing the protection of the first operational amplifier U2.

[0074] In some embodiments, Figure 7 is a schematic structural diagram of a current detection circuit of a buck-boost circuit provided by an embodiment of the present disclosure, as Figure 7As shown, the second current detection module includes: a second sampling unit 310 and a second amplification unit 320.

[0075] The second sampling unit 310 is connected in series with the buck control switch 120. The second sampling unit 310 is configured to collect a second current and convert the second current into a second voltage. The input terminal of the second amplification unit 320 is connected to the second sampling unit 310, and the output terminal of the second amplification unit 320 is connected to the total output terminal 400; the second amplification unit 320 is configured to amplify the second voltage.

[0076] Specifically, in the buck mode of the buck-boost circuit, when the buck control switch 120 is turned on, the second sampling unit 310 collects the second current in the current rising stage and converts the second current into a second voltage and outputs it to the input terminal of the second amplification unit 320. In the boost mode of the buck-boost circuit, when the boost control switch is turned off, the second sampling unit 310 collects the second current in the current falling stage and converts the second current into a second voltage and outputs it to the input terminal of the second amplification unit 320. After the second amplification unit 320 amplifies the received second voltage according to the set gain, it is then converted into a voltage through a current limiting resistor provided in the second current detection module and output to the total output terminal 400. Thus, by collecting the voltage of the total output terminal 400, the current flowing through the buck control switch 120 when the buck control switch 120 is turned on in the buck-boost circuit can be obtained, and the current flowing through the body diode of the buck control switch 120 when the boost control switch is turned off in the buck-boost circuit can be obtained.

[0077] In some embodiments, Figure 8 is a circuit diagram of a second current detection module provided by an embodiment of the present disclosure. As Figure 8 shown, the second sampling unit includes: a second current transformer U4 and a second sampling resistor R8.

[0078] Exemplarily, the second sampling unit may further include a plurality of sampling resistors. The plurality of sampling resistors and the second sampling resistor R8 may be connected in series, in parallel, or in a combination of series and parallel connections, which is not limited herein.

[0079] The primary coil of the second current transformer U4 is connected in series with the buck control switch 120. The first output terminal of the secondary coil of the second current transformer U4 is connected to the first end of the second sampling resistor R8 and the first input terminal of the second amplification unit. The second output terminal of the secondary coil of the second current transformer U4 is connected to the second end of the second sampling resistor R8 and the second input terminal of the second amplification unit. The second current transformer U4 is configured to convert the second current into a second sampling current, and the second sampling resistor R8 is configured to convert the second sampling current into a second voltage.

[0080] Exemplarily, the second amplification unit includes a second operational amplifier U5 and a third current-limiting resistor R9. The non-inverting input terminal of the second operational amplifier U5 is connected to the first output terminal of the secondary coil of the second current transformer U4, the inverting input terminal of the second operational amplifier U5 is connected to the second output terminal of the secondary coil of the second current transformer U4, and the output terminal of the second operational amplifier U5 is connected to the total output terminal 400 through the third current-limiting resistor R9.

[0081] The second current transformer U4 converts the current flowing through the buck control switch collected by the primary coil into a second sampled current of the secondary coil, so as to realize the current acquisition when the buck control switch 120 is turned on in the buck mode of the buck-boost circuit. And it realizes the current acquisition of the body diode of the buck control switch 120 when the boost control switch is turned off in the boost mode of the buck-boost circuit. The second sampling resistor R8 converts the received second sampled current into a second voltage and outputs it to the second operational amplifier U5. The second operational amplifier U5 amplifies the received second voltage according to the set gain. The amplification gain of the second operational amplifier U5 can be adjusted by the gain resistors (not shown in the figure) provided at the non-inverting input terminal and the inverting input terminal. After amplifying the second voltage, it is output to the total output terminal 400. Thus, by collecting the voltage of the total output terminal 400, the current flowing through the buck control switch 120 when the buck control switch 120 is turned on in the buck mode of the buck-boost circuit can be obtained. And the current of the body diode of the buck control switch 120 when the boost control switch is turned off in the boost mode. The present disclosure can more accurately reflect the current waveform in the buck-boost circuit by setting the second current transformer U4 to sample the current, and the amplitude of the finally collected current waveform also corresponds to the output of the second current transformer U4. Therefore, the accuracy and linearity of current detection are improved. And using a current transformer to collect current can make the circuit design more concise and reduce the circuit cost at the same time.

[0082] In some embodiments, continue to refer to Figure 8 , the second current detection module further includes a second voltage follower U6. The non-inverting input terminal of the second voltage follower U6 is connected to the output terminal of the second amplification unit, the inverting input terminal of the second voltage follower U6 is connected to the output terminal of the second voltage follower U6; the output terminal of the second voltage follower U6 is connected to the total output terminal 400.

[0083] Exemplarily, the second current detection module further includes a fourth current-limiting resistor R10. The output terminal of the second voltage follower U6 is connected to the total output terminal 400 through the fourth current-limiting resistor R10. The voltage output by the second operational amplifier U5 is output to the total output terminal 400 after passing through the second voltage follower U6, thereby realizing buffering and isolation of the output signal of the second operational amplifier U5, avoiding the interference of the current output by the second operational amplifier U5 by interference signals, and further making the output current more accurate, improving the accuracy of current detection.

[0084] In some embodiments, the second current detection module further includes a second filtering unit; the output terminal of the second voltage follower is grounded through the second filtering unit.

[0085] Specifically, the second filtering unit can filter out the interference signals in the voltage signal output by the second voltage follower, so that the current output to the total output terminal is more accurate, and further improves the accuracy of current detection.

[0086] In some embodiments, continue to refer to Figure 8 , the second current detection module further includes a third diode D9 and a fourth diode D10.

[0087] The first output terminal of the second current transformer U4 is connected to the positive terminal of the third diode D9, the negative terminal of the third diode D9 is connected to the first input terminal of the second amplification unit, the second output terminal of the second current transformer U4 is connected to the negative terminal of the fourth diode D10, and the positive terminal of the fourth diode D10 is connected to the second input terminal of the second amplification unit.

[0088] Exemplarily, the negative terminal of the third diode D9 is connected to the non-inverting input terminal of the second operational amplifier U5, and the positive terminal of the fourth diode D10 is connected to the inverting input terminal of the second operational amplifier U5. When the buck control switch 120 is turned on, the third diode D9 and the fourth diode D10 can be normally turned on to realize current acquisition. When the buck control switch 120 is turned off, the secondary coil of the second current transformer U4 demagnetizes and generates an abnormal voltage. At this time, the third diode D9 and the fourth diode D10 can be reversely cut off, thereby avoiding the abnormal output current of the second current detection module due to the voltage generated by the demagnetization of the secondary coil of the second current transformer U4 when the buck control switch 120 is turned off. Therefore, it is possible to avoid the influence of the second current detection module on the current output by the first current detection module, so that the current output by the total output terminal 400 is more accurate and the accuracy of current detection is improved.

[0089] In some embodiments, the second current detection module further includes: a third clamping unit and a fourth clamping unit; a first end of the third clamping unit is connected to a first input end of the second amplifying unit, a second end of the third clamping unit is connected to a second end of the fourth clamping unit, and a first end of the fourth clamping unit is connected to a second input end of the second amplifying unit.

[0090] Exemplarily, continuing to refer to Figure 8 , the third clamping unit may be, for example, a third clamping zener diode D11, and the fourth clamping unit may be, for example, a fourth clamping zener diode D12. The negative terminal of the third clamping zener diode D11 is connected to the non-inverting input terminal of the second operational amplifier U5, the positive terminal of the third clamping zener diode D11 is connected to the positive terminal of the fourth clamping zener diode D12, and the negative terminal of the fourth clamping zener diode D12 is connected to the inverting input terminal of the second operational amplifier U5. When the boost control switch is turned off, the demagnetization of the secondary coil of the second current transformer U4 may cause an excessively high output voltage. By providing the third clamping zener diode D11 and the fourth clamping zener diode D12 in the present disclosure, the voltage is clamped within a safe range, thereby preventing the components in the subsequent-stage circuit from being damaged due to excessive voltage.

[0091] It should be noted that the third clamping unit and the fourth clamping unit may also be circuit elements such as clamping diodes that can implement the voltage clamping function, and are not specifically limited herein.

[0092] In some embodiments, continuing to refer to Figure 8 , the second current detection module further includes: a fifth filter capacitor C7, a sixth filter capacitor C8, a seventh filter capacitor C9, an eighth filter capacitor C30, a fourth filter resistor R11, a fifth filter resistor R12, a sixth filter resistor R13, a second load resistor R14, a fifth clamping diode D13, a sixth clamping diode D14, a seventh clamping diode D15, and an eighth clamping diode D16.

[0093] A first end of the fifth filter capacitor C7 is connected to the non-inverting input terminal of the second operational amplifier U5, a second end of the fifth filter capacitor C7 is connected to the inverting input terminal of the second operational amplifier U5, and the second load resistor R14 is connected in parallel with the fifth filter capacitor C7. The non-inverting input terminal of the second operational amplifier U5 is grounded through the sixth filter capacitor C8, and the fourth filter resistor R11 is connected in parallel with the sixth filter capacitor C8. The inverting input terminal of the second operational amplifier U5 is connected to a first end of the seventh filter capacitor C9, a second end of the seventh filter capacitor C9 is connected to the output terminal of the second operational amplifier U5, and the fifth filter resistor R12 is connected in parallel with the seventh filter capacitor C9. The output terminal of the second voltage follower U6 is grounded through the fourth current limiting resistor R10 and the eighth filter capacitor C30, and the sixth filter resistor R13 is connected in parallel with the fourth filter capacitor.

[0094] Therefore, the fifth filter capacitor C7, the sixth filter capacitor C8, the seventh filter capacitor C9, the fourth filter resistor R11, and the fifth filter resistor R12 can filter out the interference signals in the voltage signal input to the second operational amplifier U5 and the voltage signal output by the second operational amplifier U5. The eighth filter capacitor C30 and the sixth filter resistor R13 can filter out the interference signals in the voltage signal output by the second voltage follower U6, so that the current output to the total output terminal 400 is more accurate, thereby improving the accuracy of current detection.

[0095] The positive terminal of the fifth clamping diode D13 is connected to the non-inverting input terminal of the second operational amplifier U5, and the negative terminal of the fifth clamping diode D13 is connected to the first power supply terminal VCC. The positive terminal of the sixth clamping diode D14 is grounded, and the negative terminal of the sixth clamping diode D14 is connected to the non-inverting input terminal of the second operational amplifier U5. The positive terminal of the seventh clamping diode D15 is connected to the inverting input terminal of the second operational amplifier U5, and the negative terminal of the seventh clamping diode D15 is connected to the first power supply terminal VCC. The positive terminal of the eighth clamping diode D16 is grounded, and the negative terminal of the eighth clamping diode D16 is connected to the inverting input terminal of the second operational amplifier U5.

[0096] The fifth clamping diode D13 and the sixth clamping diode D14 can clamp the voltage input to the non-inverting input terminal of the second operational amplifier U5, and the seventh clamping diode D15 and the eighth clamping diode D16 can clamp the voltage input to the inverting input terminal of the second operational amplifier U5, thereby protecting the second operational amplifier U5.

[0097] Figure 9 FIG. is a schematic structural diagram of a current detection circuit of a buck-boost circuit provided by an embodiment of the present disclosure. As Figure 9 shown, the current detection circuit further includes: a fifth diode D17 and a sixth diode D18.

[0098] The negative terminal of the fifth diode D17 is connected to the total output terminal 400, and the positive terminal of the fifth diode D17 is connected to the output terminal of the first current detection module 200; the negative terminal of the sixth diode D18 is connected to the total output terminal 400, and the positive terminal of the sixth diode D18 is connected to the output terminal of the second current detection module 300.

[0099] Specifically, the fifth diode D17 can reversely cut off the current flowing from the second current detection module 300 to the first current detection module 200, thereby avoiding the interference of the current signal output by the second current detection module 300 on the first current detection module 200. The sixth diode D18 can reversely cut off the current flowing from the first current detection module 200 to the second current detection module 300, thereby avoiding the interference of the current signal output by the first current detection module 200 on the second current detection module 300.

[0100] Preferably, the current detection circuit further includes a temperature detection module, which is used to detect the temperature of the current detection circuit, so that the parameters of the current detection circuit can be dynamically adjusted according to the detected temperature to adapt to the temperature change.

[0101] The embodiment of the present disclosure also provides a buck-boost circuit, which is used to be connected to the current detection circuit provided in any of the above embodiments. Figure 10 As shown in the structural schematic diagram of a buck-boost circuit provided by the embodiment of the present disclosure, Figure 10 as shown, the buck-boost circuit includes: a boost control switch 110, a buck control switch 120, a first inductor L1, a first capacitor C1, and a second capacitor C2.

[0102] The low-voltage end 101 of the buck-boost circuit is connected to the first end of the first inductor L1. The second end of the first inductor L1 is connected to the first end of the boost control switch 110 and the first end of the buck control switch 120. The second end of the boost control switch 110 is grounded. The second end of the buck control switch 120 is connected to the high-voltage end 102 of the buck-boost circuit. The first end of the first inductor L1 is grounded through the first capacitor C1. The second end of the buck control switch 120 is grounded through the second capacitor C2. The boost control switch 110 is connected to the first current detection module 200, the buck control switch 120 is connected to the second current detection module 300, and the sampling output ends of the first current detection module 200 and the second current detection module 300 are connected to the total output end 400.

[0103] The total output end 400 is used to output the detected current of the current detection circuit; the detected current is used to realize the current detection of the buck-boost circuit.

[0104] Exemplarily, the boost control switch 110 and the buck control switch 120 may include semiconductor switching devices such as MOS transistors and triodes.

[0105] It can be understood that the buck-boost circuit provided by the embodiment of the present application can achieve the corresponding beneficial effects of the current detection circuit provided by the above embodiments, which will not be elaborated here.

[0106] It should be noted that in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0107] The above are only specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A current detection circuit for a buck-boost circuit, characterized in that: include: A first current detection module connected to the boost control switch of the boost-buck circuit; A second current detection module is connected to the buck control switch of the buck-boost circuit; In the boost mode of the buck-boost circuit, the first current detection module is used to collect a first current in a current rising stage, and the second current detection module is used to collect a second current in a current falling stage; In the buck mode of the buck-boost circuit, the first current detection module is used to collect the first current in the current decreasing stage, and the second current detection module is used to collect the second current in the current increasing stage; The sampling output end of the first current detection module and the sampling output end of the second current detection module are connected to the total output end; Wherein, the total output end is used to output the detection current of the current detection circuit; the detection current is used to realize the current detection of the buck-boost circuit.

2. The current detection circuit according to claim 1, characterized in that: The first current detection module includes: A first sampling unit, connected in series with the boost control switch, the first sampling unit being used to collect the first current and convert the first current into a first voltage; a first amplifying unit, wherein an input end of the first amplifying unit is connected to the first sampling unit, and an output end of the first amplifying unit is connected to the total output end; the first amplifying unit is used to amplify the first voltage; The second current detection module includes: A second sampling unit, connected in series with the step-down control switch, the second sampling unit is used to collect the second current and convert the second current into a second voltage; A second amplifying unit, wherein the input end of the second amplifying unit is connected to the second sampling unit, and the output end of the second amplifying unit is connected to the total output end; the second amplifying unit is used to amplify the second voltage.

3. The current detection circuit according to claim 2, characterized in that: The first sampling unit includes: a first current transformer and a first sampling resistor; The first current transformer is connected in series with the boost control switch, a first output end of the first current transformer is connected with a first end of the first sampling resistor and a first input end of the first amplifying unit, and a second output end of the first current transformer is connected with a second end of the first sampling resistor and a second input end of the first amplifying unit; The first current transformer is used to convert the first current into a first sampling current, and the first sampling resistor is used to convert the first sampling current into the first voltage; The second sampling unit includes: a second current transformer and a second sampling resistor; The second current transformer is connected in series with the step-down control switch, a first output end of the second current transformer is connected with a first end of the second sampling resistor and a first input end of the second amplifying unit, and a second output end of the second current transformer is connected with a second end of the second sampling resistor and a second input end of the second amplifying unit; The second current transformer is used to convert the second current into a second sampling current, and the second sampling resistor is used to convert the second sampling current into the second voltage.

4. The current detection circuit according to claim 3, characterized in that: The first current detection module also includes a first voltage follower; The non-inverting input terminal of the first voltage follower is connected to the output terminal of the first amplifying unit, the inverting input terminal of the first voltage follower is connected to the output terminal of the first voltage follower; the output terminal of the first voltage follower is connected to the total output terminal; The second current detection module also includes a second voltage follower; The non-inverting input terminal of the second voltage follower is connected to the output terminal of the second amplifying unit, the inverting input terminal of the second voltage follower is connected to the output terminal of the second voltage follower; and the output terminal of the second voltage follower is connected to the total output terminal.

5. The current detection circuit according to claim 4, characterized in that: The first current detection module also includes a first filtering unit; The output end of the first voltage follower is grounded through the first filtering unit; The second current detection module also includes a second filtering unit; The output terminal of the second voltage follower is grounded through the second filtering unit.

6. The current detection circuit according to claim 3, characterized in that: The first current detection module also includes a first diode and a second diode; The first output end of the first current transformer is connected to the positive terminal of the first diode, the negative terminal of the first diode is connected to the first input end of the first amplifying unit, the second output end of the first current transformer is connected to the negative terminal of the second diode, and the positive terminal of the second diode is connected to the second input end of the first amplifying unit; The second current detection module also includes a third diode and a fourth diode; The first output end of the second current transformer is connected to the positive end of the third diode, the negative end of the third diode is connected to the first input end of the second amplifying unit, the second output end of the second current transformer is connected to the negative end of the fourth diode, and the positive end of the fourth diode is connected to the second input end of the second amplifying unit.

7. The current detection circuit according to claim 2, characterized in that: The first current detection module further includes: a first clamping unit and a second clamping unit; The first end of the first clamping unit is connected to the first input end of the first amplifying unit, the second end of the first clamping unit is connected to the second end of the second clamping unit, and the first end of the second clamping unit is connected to the second input end of the first amplifying unit; The second current detection module further includes: a third clamping unit and a fourth clamping unit; The first end of the third clamping unit is connected to the first input end of the second amplifying unit, the second end of the third clamping unit is connected to the second end of the fourth clamping unit, and the first end of the fourth clamping unit is connected to the second input end of the second amplifying unit.

8. The current detection circuit according to any one of claims 1 to 7, characterized in that: The current detection circuit further includes: a fifth diode and a sixth diode; The cathode terminal of the fifth diode is connected to the total output terminal, and the anode terminal of the fifth diode is connected to the output terminal of the first current detection module; the cathode terminal of the sixth diode is connected to the total output terminal, and the anode terminal of the sixth diode is connected to the output terminal of the second current detection module.

9. A step-up / step-down circuit, characterized in that: Connected to the current detection circuit according to any one of claims 1 to 8; the buck-boost circuit comprises: a boost control switch, a buck control switch, a first inductor, a first capacitor and a second capacitor; The low voltage end of the buck-boost circuit is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the boost control switch and the first end of the buck control switch, the second end of the boost control switch is grounded, the second end of the buck control switch is connected to the high voltage end of the buck-boost circuit, the first end of the first inductor is grounded through the first capacitor, and the second end of the buck control switch is grounded through the second capacitor.

10. The step-up / down voltage circuit according to claim 9, characterized in that: The boost control switch and the buck control switch both include semiconductor switch devices.

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