Bidirectional current detection circuit

Abstract

The application provides a bidirectional current detection circuit, which converts a to-be-detected current into two differential voltages through a differential current sampling module, and respectively performs voltage lifting and amplification processing, so that the voltage values of the two differential voltages after processing are positive, regardless of whether the to-be-detected current is positive or negative, thereby realizing subsequent capacitor charging and voltage value comparison; then, in order to adapt to different directions of the to-be-detected current, a current direction comparison module is used to control one of the output lines to be the larger one of the differential voltages after processing, so as to charge a first capacitor in the later stage, and control the other output line to be the smaller one of the differential voltages after processing, so as to charge a second capacitor in the later stage; finally, a switched capacitor dynamic comparison module controls the charge transfer of the capacitors in two stages, and finally the value range of the to-be-detected capacitor can be obtained according to the comparison result of the comparator; in this way, through the synergistic effect of the modules, the detection circuit can be applied to both forward current and reverse current.

Description

Technical Field

[0001] This application relates to the field of current detection technology, and in particular to a bidirectional current detection circuit. Background Technology

[0002] In applications such as motor drives and switching power supplies, it is necessary to monitor the current flowing through the switching transistor in order to accurately control the output voltage and current. Traditional detection circuits can usually only detect current in one direction. However, in practical applications, the current direction can be both positive and negative. Therefore, it is particularly necessary to design a bidirectional current detection circuit. Summary of the Invention

[0003] This application provides a bidirectional current detection circuit capable of bidirectional current detection.

[0004] A bidirectional current detection circuit includes:

[0005] A differential current sampling module includes a sampling resistor connected in series in the current loop to be measured. The differential current sampling module is used to acquire the voltage across the sampling resistor to obtain a first voltage and a second voltage, and to perform voltage boosting and amplification on the first voltage and the second voltage respectively. The first voltage and the second voltage after voltage boosting and amplification are both greater than 0, and the voltage difference is equal to the product of the voltage difference between the first voltage and the second voltage before voltage boosting and amplification and the sampling gain.

[0006] The current direction comparison module is connected to the differential current sampling module and is used to receive the first voltage and the second voltage after voltage boosting and amplification, and output the larger of the first voltage and the second voltage as the first target voltage, and output the smaller of the first voltage and the second voltage as the second target voltage.

[0007] A switched-capacitor dynamic comparison module, connected to the current direction comparison module, includes a first capacitor, a second capacitor, and a comparator. The switched-capacitor dynamic comparison module is used to first control the first target voltage and the common-mode voltage to charge the first capacitor, and the second target voltage and the common-mode voltage to charge the second capacitor. Then, it controls the first capacitor to be connected to the first reference power supply and the inverting input terminal of the comparator, respectively, and controls the second capacitor to be connected to the second reference power supply and the non-inverting input terminal of the comparator, respectively, so as to obtain the comparison result at the comparator output terminal.

[0008] In one embodiment, the differential current sampling module includes: load unit R1, load unit R2, load unit R3, load unit R4, load unit R5, load unit R6, load unit R7, a first operational amplifier, and a second operational amplifier; a first terminal of load unit R1 is connected to one end of the sampling resistor, and a second terminal of load unit R1 is connected to the first terminal of load unit R2 and the non-inverting input of the first operational amplifier; a first terminal of load unit R3 is connected to the other end of the sampling resistor, and a second terminal of load unit R3 is connected to the first terminal of load unit R4 and the non-inverting input of the second operational amplifier. The non-inverting input is connected; the second terminals of the load unit R3 and the second terminals of the load unit R4 are respectively used to receive the common-mode voltage; the output terminal of the first operational amplifier is connected to the first terminal of the load unit R5 and the current direction comparison module, and the inverting input terminal of the first operational amplifier is connected to the second terminal of the load unit R5 and the first terminal of the load unit R6, respectively; the output terminal of the second operational amplifier is connected to the first terminal of the load unit R7 and the current direction comparison module, and the inverting input terminal of the second operational amplifier is connected to the second terminal of the load unit R7 and the second terminal of the load unit R6, respectively.

[0009] In one embodiment, the load units R1, R2, R3, and R4 have the same resistance value.

[0010] In one embodiment, the current direction comparison module includes: control switch SW1, control switch SW2, control switch SW3, and control switch SW4; the first terminals of control switch SW1 and control switch SW3 are respectively connected to the output terminals of the first operational amplifier; the first terminals of control switch SW2 and control switch SW4 are respectively connected to the output terminals of the second operational amplifier; the second terminals of control switch SW1, control switch SW2, control switch SW3, and control switch SW4 are respectively connected to the switched capacitor dynamic comparison module.

[0011] In one embodiment, the current direction comparison module includes: a third operational amplifier, a first inverter, and a second inverter; the non-inverting input of the third operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the third operational amplifier is connected to the output of the second operational amplifier; the output of the third operational amplifier is connected to the input of the first inverter, and the output of the first inverter is connected to the input of the second inverter, the control terminal of the control switch SW2, and the control terminal of the control switch SW3, respectively; the output of the second inverter is connected to the control terminal of the control switch SW1 and the control terminal of the control switch SW4, respectively.

[0012] In one embodiment, the switched capacitor dynamic comparison module further includes: control switches SW5, SW6, SW7, SW8, SW9, and SW10; load units R8, R9, R10, and R11; a first terminal of load unit R8 is connected to a second terminal of control switch SW1, and a second terminal of load unit R8 is connected to a first terminal of control switch SW5; a first terminal of load unit R9 is connected to the first reference power supply, and a second terminal of load unit R9 is connected to a first terminal of control switch SW6; the second terminals of control switch SW5 and control switch SW6 are respectively connected to the first terminal of the first capacitor; the first capacitor... The second terminal is connected to the first terminal of the control switch SW9 and the inverting input terminal of the comparator, respectively; the first terminal of the load unit R11 is connected to the second terminal of the control switch SW3, and the second terminal of the load unit R11 is connected to the first terminal of the control switch SW8; the first terminal of the load unit R10 is connected to the second reference power supply, and the second terminal of the load unit R10 is connected to the first terminal of the control switch SW7; the second terminals of the control switches SW7 and SW8 are respectively connected to the first terminal of the second capacitor; the second terminal of the second capacitor is respectively connected to the first terminal of the control switch SW10 and the non-inverting input terminal of the comparator, respectively; the second terminal of the control switch SW9 is connected to the second terminal of the control switch SW10.

[0013] In one embodiment, the control terminals of control switches SW5, SW8, SW9, and SW10 are all connected to receive the same control signal.

[0014] In one embodiment, the control terminals of control switch SW6 and control switch SW7 are connected together to receive the same control signal.

[0015] In one embodiment, the comparator compares the voltages at the positive and negative terminals within a preset time period after the control switches SW6 and SW7 begin to close.

[0016] The above-mentioned differential current sampling module converts the current to be measured into two differential voltages, and performs voltage boosting and amplification processing on each to ensure that the voltage values ​​of the two differential voltages are positive regardless of whether the current to be measured is positive or negative, thereby realizing subsequent capacitor charging and voltage value comparison. Then, to adapt to different directions of the current to be measured, the current direction comparison module controls one of its output lines to always be the larger of the processed differential voltages to charge the first capacitor later, while the other line is always the smaller of the processed differential voltages to charge the second capacitor later. Finally, the switching capacitor dynamic comparison module performs two stages of charge transfer control on the capacitor. The value range of the capacitor to be measured can be determined based on the comparison result of the comparator. In this way, through the synergistic effect of each module, the detection circuit can be used for both forward and reverse currents. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a bidirectional current detection circuit according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the bidirectional current detection circuit according to another embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the bidirectional current detection circuit according to another embodiment of this application;

[0020] Figure 4 This is a schematic diagram of the bidirectional current detection circuit according to another embodiment of this application;

[0021] Figure 5 This is a schematic diagram of the bidirectional current detection circuit according to another embodiment of this application;

[0022] Figure 6 This is a timing diagram of control signals according to an embodiment of this application. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly. The connection can be a direct connection or an indirect connection.

[0026] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0027] Figure 1 Here is a block diagram of a bidirectional current detection circuit according to one embodiment, such as Figure 1As shown, the bidirectional current detection circuit includes a differential current sampling module 110, a current direction comparison module 120, and a switched capacitor dynamic comparison module 130. The differential current sampling module 110 includes a sampling resistor R0. The differential current sampling module 110 is used to collect the voltage across the sampling resistor R0 to obtain a first voltage U1 and a second voltage U2, and to perform voltage boosting and amplification on the first voltage U1 and the second voltage U2 respectively. The boosted and amplified first voltage U1 and second voltage U2 are both greater than 0, and the voltage difference is equal to the product of the voltage difference between the first voltage U1 and the second voltage U2 before voltage boosting and amplification and the sampling gain. The current direction comparison module 120 is connected to the differential current sampling module 110 and is used to receive the first voltage U1 and the second voltage U2, and output the voltage boosted and amplified voltage U2. The larger of the first voltage VO1 and the second voltage VO2 is taken as the first target voltage, and the smaller of the first voltage U1 and the second voltage U2 after voltage boosting and amplification is taken as the second target voltage. The switched capacitor dynamic comparison module 130 is connected to the current direction comparison module 120 and includes a first capacitor C1, a second capacitor C2 and a comparator 131. The switched capacitor dynamic comparison module 130 is used to first control the first target voltage and the common mode voltage to charge the two ends of the first capacitor C1, and the second target voltage and the common mode voltage to charge the two ends of the second capacitor C2. Then, it controls the two ends of the first capacitor C1 to be connected to the first reference power supply and the inverting input terminal of the comparator 131 respectively, and controls the two ends of the second capacitor C2 to be connected to the second reference power supply and the non-inverting input terminal of the comparator 131 respectively, so as to obtain the comparison result at the output terminal of the comparator 131.

[0028] It is understood that the sampling resistor R0 in the differential current sampling module 110 can convert the current signal to be measured into a corresponding voltage signal. Then, the differential current sampling module 110 acquires the first voltage U1 and the second voltage U2 across the sampling resistor R0. To prevent the first voltage U1 and the second voltage U2 from being negative when the direction of the current to be measured is reversed, voltage boosting and amplification processing is required. This ensures that the charge can be smoothly transferred to the comparator 131 after the first capacitor C1 and the second capacitor C2 are subsequently charged. The processed first voltage U1 is represented by VO1, and the second voltage U2 is represented by VO2. After receiving the processed first voltage VO1 and second voltage VO2, the current direction comparison module 120 transmits them to the first capacitor C1 and the second capacitor C2 of the switched capacitor dynamic comparison module 130 for charging. Considering that the direction of the current to be measured can be bidirectional, the magnitude relationship between the processed first voltage VO1 and second voltage VO2 may change. The voltage that charges the first capacitor C1 is the larger of the processed first voltage VO1 and second voltage VO2 (represented by the first target voltage VA), while the voltage that charges the second capacitor C2 is the smaller one (represented by the second target voltage VB). Therefore, in order to ensure that the first capacitor C1 and the second capacitor C2 can be correctly charged regardless of the direction of the current to be measured, a current direction comparison module 120 can be set to output a larger first target voltage VA to the end connected to the first capacitor C1 and a smaller second target voltage VB to the end connected to the second capacitor C2.

[0029] The switching capacitor dynamic comparison module 130 controls the first capacitor C1 and the second capacitor C2 in two stages. First, the first target voltage VA and the common mode voltage VCM are controlled to charge the first capacitor C1, and the second target voltage VB and the common mode voltage VCM are controlled to charge the second capacitor C2. Thus, the charge on the first capacitor C1 is QC1 = C1*(VA-VCM), and the charge on the second capacitor C2 is QC2 = C2(VB-VCM).

[0030] Then, in the second stage, the first capacitor C1 is connected to the first reference power supply and the inverting input of comparator 131, respectively, and the second capacitor C2 is connected to the second reference power supply and the non-inverting input of comparator 131, respectively. Let the voltage of the first reference power supply be VDAC, the voltage of the second reference power supply be 0V, the capacitance of the first capacitor C1 be equal to the capacitance of the second capacitor C2, and the voltage at the non-inverting input of comparator 131 be V+ and the voltage at the inverting input of comparator 131 be V-. Thus, the charge across the first capacitor C1 is QC1 = C1 * (VDAC - V-), and the charge across the second capacitor C2 is QC2 = C2 * (0 - V+). According to the law of conservation of charge, we have:

[0031] QC1=C1*(VA-VCM)=C1*(VDAC-V-)

[0032] From this we can obtain

[0033] V- = VDAC - VA + VCM

[0034] Similarly, there are also:

[0035] QC2=C2(VB-VCM)=C2*(0-V+)

[0036] Therefore, we can obtain

[0037] V+ = VCM - VB

[0038] Therefore:

[0039] (V+)-(V-)=(VA-VB)-VDAC (Formula 1)

[0040] Where VA is the larger of the processed first voltage VO1 and second voltage VO2, and VB is the smaller, and the voltage difference between the processed first voltage VO1 and second voltage VO2 is equal to the product of the voltage difference between the unprocessed first voltage U1 and second voltage U2 and the sampling gain Gain, let the first target voltage VA be V01 and the second target voltage VB be V02, then we have:

[0041] (V01-V02)=(VA-VB)=Gain|U1-U2|=|Gain*Io*R0|

[0042] Combining Formula 1, we can obtain:

[0043] (V+)-(V-)=|Gain*Io*R0|-VDAC

[0044] Since the sampling gain Gain, sampling resistor R0, and VDAC are all known, when the comparator 131 outputs a high level, it indicates that V+ is greater than V-, i.e., |Gain*Io*R0|-VDAC>0, thus the numerical range of the measured current Io can be obtained. Similarly, when the comparator 131 outputs a high level, it indicates that V+ is less than V-, i.e., |Gain*Io*R0|-VDAC<0, thus the numerical range of the measured current Io can be obtained. The value of VDAC can be set by the user.

[0045] By setting up a differential current sampling module 110, the current to be measured is converted into two differential voltages, and voltage boosting and amplification are performed respectively to ensure that the voltage values ​​of the two differential voltages are positive regardless of whether the current to be measured is positive or negative, thereby realizing subsequent capacitor charging and voltage value comparison. Then, to adapt to different directions of the current to be measured, the current direction comparison module 120 controls one of its output lines to always be the larger of the processed differential voltages to charge the first capacitor C1 later, while the other line is always the smaller of the processed differential voltages to charge the second capacitor C2 later. Finally, the switched capacitor dynamic comparison module 130 performs two stages of charge transfer control on the capacitors. The value range of the capacitor to be measured can be determined based on the comparison result of the comparator 131. In this way, through the synergistic effect of each module, the detection circuit can be used for both forward and reverse currents. Furthermore, due to the use of a fully differential structure, the system offset voltage is reduced, ultimately improving the current detection accuracy.

[0046] In one embodiment, such as Figure 2 As shown, the differential current sampling module 110 includes: load unit R1, load unit R2, load unit R3, load unit R4, load unit R5, load unit R6, load unit R7, a first operational amplifier 111, and a second operational amplifier 112; the first terminal of load unit R1 is connected to one end of the sampling resistor R0, and the second terminal of load unit R1 is connected to the first terminal of load unit R2 and the non-inverting input of the first operational amplifier 111; the first terminal of load unit R3 is connected to the other end of the sampling resistor, and the second terminal of load unit R3 is connected to the first terminal of load unit R4 and the second operational amplifier 112. The non-inverting input of the first operational amplifier 111 is connected to the first terminal of the load unit R5 and the current direction comparison module 120, respectively; the inverting input of the first operational amplifier 111 is connected to the second terminal of the load unit R5 and the first terminal of the load unit R6, respectively; the output of the second operational amplifier 112 is connected to the first terminal of the load unit R7 and the current direction comparison module 120, respectively; the inverting input of the second operational amplifier 112 is connected to the second terminal of the load unit R7 and the second terminal of the load unit R6, respectively.

[0047] It can be understood that the differential current sampling module 110 has a differential structure. The resistance values ​​of load unit R1 and load unit R3 are the same, and the resistance values ​​of load unit R2 and load unit R4 are the same. Based on the virtual short characteristic of the operational amplifier, the voltage VP1 at the non-inverting input terminal of the first operational amplifier 111 is equal to the voltage VN1 at the inverting input terminal, and the voltage VP2 at the non-inverting input terminal of the second operational amplifier 112 is equal to the voltage VN2 at the inverting input terminal. Let R2 = nR1, R4 = nR3, where n is a constant. Based on the virtual open characteristic of the operational amplifier, the voltage division at the input terminals can be obtained as follows:

[0048] VP1 = (U1 + VCM) / (n + 1)

[0049] VP2 = (U2 + VCM) / (n + 1)

[0050] Since the load current flowing through the output terminal of the fully differential op-amp is equal, we have:

[0051] (VO1-VO2) / (R5+R6+R7)=(VN1-VN2) / R6

[0052] VO1-VO2=[(R5+R6+R7) / R6]*(VN1-VN2)

[0053] Substituting VN1 and VN2 into VP1 and VP2 respectively, we get:

[0054] VO1-VO2=[(R5+R6+R7) / (n+1)R6]*(U1-U2)

[0055] Since the voltage difference between the first voltage VO1 and the second voltage VO2 after voltage boosting and amplification is equal to the product of the voltage difference between the first voltage U1 and the second voltage U2 before voltage boosting and amplification and the sampling gain Gain, the sampling gain Gain can be expressed as (R5+R6+R7) / (n+1)R6; and since the voltage difference U1-U2 between the first voltage U1 and the second voltage U2 can be expressed as |Io*R0|, then:

[0056] VO1-VO2=|Io*R0*Gain|

[0057] Therefore, the circuit described above can be used to boost and amplify the first voltage U1 and the second voltage U2. Furthermore, by appropriately setting the resistance values ​​of the load units R5, R6, and R7, and the proportional relationships between load units R1 and R2, and R3 and R4, the desired sampling gain can be obtained. This circuit has a simple structure and the sampling gain is adjustable. In some embodiments, each load unit may include a resistive element.

[0058] In one embodiment, the resistance values ​​of load units R1, R2, R3, and R4 are the same.

[0059] It is understandable that when the resistance values ​​of load units R1, R2, R3, and R4 are the same, i.e., R2 = R1 and R4 = R3, then:

[0060] Gain = (R5 + R6 + R7) / 2R6

[0061] This simplifies the gain expression; the desired sampling gain can be obtained simply by adjusting the resistance values ​​of load units R5, R6, and R7.

[0062] In one embodiment, such as Figure 3 As shown, the current direction comparison module 120 includes: control switch SW1, control switch SW2, control switch SW3 and control switch SW4; the first terminal of control switch SW1 and the first terminal of control switch SW3 are respectively connected to the output terminal of the first operational amplifier 111; the first terminal of control switch SW2 and the first terminal of control switch SW4 are respectively connected to the output terminal of the second operational amplifier 112; the second terminals of control switch SW1, control switch SW2, control switch SW3 and control switch SW4 are respectively connected to the switched capacitor dynamic comparison module 130.

[0063] It can be understood that in the current direction comparison module 120, by controlling the four control switches respectively, the first voltage VO1 and the second voltage VO2 after voltage boosting and amplification can be output as the first target voltage VA or the second target voltage VB. Control switches SW1 and SW3 are selectively turned on, as are control switches SW2 and SW4. For example, when the first voltage VO1 after voltage boosting and amplification is greater than the second voltage VO2, control switches SW1 and SW4 are closed, and control switches SW2 and SW3 are open. In this way, VO1 can be used as the first target voltage VA, and VO2 as the second target voltage VB. Conversely, when the first voltage VO1 after voltage boosting and amplification is less than the second voltage VO2, control switches SW2 and SW3 are closed, and control switches SW1 and SW4 are open. In this way, VO2 can be used as the first target voltage VA, and VO1 as the second target voltage VB.

[0064] In this way, two voltages can be output according to a specific path by simply switching on a switch, which solves the problem that the two voltages change due to the change in the direction of the current being measured, thus affecting the subsequent circuit's ability to receive only a specific voltage, and realizes bidirectional current detection.

[0065] In one embodiment, such as Figure 4 As shown, the current direction comparison module includes: a third operational amplifier 121, a first inverter 122, and a second inverter 123; the non-inverting input of the third operational amplifier 121 is connected to the output of the first operational amplifier 121, and the inverting input of the third operational amplifier 121 is connected to the output of the second operational amplifier 122; the output of the third operational amplifier 121 is connected to the input of the first inverter 122, and the output of the first inverter 122 is connected to the input of the second inverter 123, the control terminal of control switch SW2, and the control terminal of control switch SW3, respectively; the output of the second inverter 123 is connected to the control terminal of control switch SW1 and the control terminal of control switch SW4, respectively.

[0066] It can be understood that the output signal of the first inverter 122 is SWN, and the output signal of the second inverter 123 is SWP. The signal SWN is used to control the opening and closing of control switches SW2 and SW3, and the signal SWP is used to control the opening and closing of control switches SW1 and SW4. When voltage VO1 is greater than voltage VO2, signal SWN is low and signal SWP is high, thereby turning on control switches SW1 and SW4, and turning off control switches SW2 and SW3, so that voltage VO1 is the first target voltage VA and voltage VO2 is the second target voltage VB. When voltage VO1 is less than voltage VO2, signal SWN is high and signal SWP is low, thereby turning off control switches SW1 and SW4, and turning on control switches SW2 and SW3, so that voltage VO2 is the first target voltage VA and voltage VO1 is the second target voltage VB, thus ensuring that the voltage is output according to the correct path.

[0067] In one embodiment, such as Figure 5As shown, the switched capacitor dynamic comparison module 130 further includes: control switches SW5, SW6, SW7, SW8, SW9, and SW10; load units R8, R9, R10, and R11; the first terminal of load unit R8 is connected to the second terminal of control switch SW1, and the second terminal of load unit R8 is connected to the first terminal of control switch SW5; the first terminal of load unit R9 is connected to a first reference power supply (not shown), and the second terminal of load unit R9 is connected to the first terminal of control switch SW6; the second terminals of control switches SW5 and SW6 are respectively connected to the first terminal of the first capacitor C1; the first capacitor C1... The second terminal of the load unit R11 is connected to the first terminal of the control switch SW9 and the inverting input terminal of the comparator 131, respectively; the first terminal of the load unit R11 is connected to the second terminal of the control switch SW3, and the second terminal of the load unit R11 is connected to the first terminal of the control switch SW8; the first terminal of the load unit R10 is connected to the second reference power supply (not shown), and the second terminal of the load unit R10 is connected to the first terminal of the control switch SW7; the second terminals of the control switches SW7 and SW8 are respectively connected to the first terminal of the second capacitor C2; the second terminal of the second capacitor C2 is respectively connected to the first terminal of the control switch SW10 and the non-inverting input terminal of the comparator 131; the second terminal of the control switch SW9 is connected to the second terminal of the control switch SW10.

[0068] The first reference power supply can be a digital-to-analog converter (DAC), which provides a first reference voltage VDAC. The second reference power supply can be a reference ground, which provides a second reference voltage VSS, which can be 0V. Control switches SW5 and SW8, along with control switches SW6 and SW7, form two sets of switch pairs. The switched capacitor dynamic comparison module 130 controls one of these two sets of switches to be turned on, thereby realizing capacitor charging and charge redistribution. The following is a brief description of the operation of the switched capacitor dynamic comparison module 130.

[0069] In the first stage, the switched-capacitor dynamic comparison module 130 controls control switches SW5, SW8, SW9, and SW10 to close, and control switches SW6 and SW7 to open, causing the first target voltage VA and common-mode voltage VCM to charge the first capacitor C1, and the second target voltage VB and common-mode voltage VCM to charge the second capacitor C2. Then, in the second stage, the switched-capacitor dynamic comparison module 130 controls control switches SW5, SW8, SW9, and SW10 to open, and control switches SW6 and SW7 to close, causing the first capacitor C1 to connect to the first reference power supply, and the second capacitor C2 to connect to the second reference power supply, thereby achieving charge redistribution. The specific charge change process can be found in [reference needed]. Figure 1 The specific details in the embodiments are not repeated here.

[0070] In one embodiment, the control terminals of control switches SW5, SW8, SW9, and SW10 are connected together to receive the same control signal.

[0071] For example, if signal S1 is used as the control signal for control switches SW5, SW8, SW9, and SW10, the control timing of signal S1 can be referenced. Figure 6 As shown, when signal S1 is high, the control switch is closed; when it is low, the control switch is open. By connecting the control terminals of the above control switches, one-button control can be achieved, simplifying the control process.

[0072] In one embodiment, the control terminals of control switch SW6 and control switch SW7 are connected together to receive the same control signal.

[0073] For example, if signal S2 is used as the control signal for control switches SW6 and SW7, the control timing of signal S2 can be referenced. Figure 6 As shown, when signal S2 is high, the control switch is closed; when it is low, the control switch is open. By connecting the control terminals of the above control switches, one-button control can be achieved, simplifying the control process.

[0074] In one embodiment, comparator 131 performs voltage comparison between the positive and negative terminals within a preset time period after control switches SW6 and SW7 begin to close.

[0075] The control timing of comparator 131 and control switches SW6 and SW7 can be referenced. Figure 6 As shown, signal CLK is the reference clock signal of the switched capacitor dynamic comparison module 130, and signal CLK_CMP is the clock signal of comparator 131. In order to ensure that the charge on the first capacitor C1 and the second capacitor C2 has enough time to be redistributed after the control switch is switched, so as to ensure that the output result of comparator 131 is accurate, the comparator 131 can be driven to perform comparison after a certain period of time after the control switch SW6 and the control switch SW7 start to close.

[0076] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A bidirectional current detection circuit, characterized in that, include: A differential current sampling module includes a sampling resistor connected in series in the current loop to be measured. The differential current sampling module is used to acquire the voltage across the sampling resistor to obtain a first voltage and a second voltage, and to perform voltage boosting and amplification on the first voltage and the second voltage respectively. The first voltage and the second voltage after voltage boosting and amplification are both greater than 0, and the voltage difference is equal to the product of the voltage difference between the first voltage and the second voltage before voltage boosting and amplification and the sampling gain. A current direction comparison module includes: control switches SW1, SW2, SW3, and SW4; the first terminals of control switches SW1 and SW3 are respectively connected to the first output terminal of the differential current sampling module; the first terminals of control switches SW2 and SW4 are respectively connected to the second output terminal of the differential current sampling module; the second terminals of control switches SW1, SW2, SW3, and SW4 are respectively connected to a switched capacitor dynamic comparison module; the first output terminal is used to output a first voltage after voltage boosting and amplification, and the second output terminal is used to output a second voltage after voltage boosting and amplification; the current direction comparison module is used to receive the first voltage and the second voltage after voltage boosting and amplification, and output the larger of the first voltage and the second voltage as a first target voltage, and output the smaller of the first voltage and the second voltage as a second target voltage; The switched capacitor dynamic comparison module includes a first capacitor, a second capacitor, and a comparator. The switched capacitor dynamic comparison module is used to first control the first target voltage and the common-mode voltage to charge the two ends of the first capacitor, and the second target voltage and the common-mode voltage to charge the two ends of the second capacitor. Then, it controls the two ends of the first capacitor to be connected to the first reference power supply and the inverting input terminal of the comparator, respectively, and controls the two ends of the second capacitor to be connected to the second reference power supply and the non-inverting input terminal of the comparator, respectively, so as to obtain the comparison result at the output terminal of the comparator.

2. The bidirectional current detection circuit according to claim 1, characterized in that, The differential current sampling module includes: load unit R1, load unit R2, load unit R3, load unit R4, load unit R5, load unit R6, load unit R7, a first operational amplifier, and a second operational amplifier. The first end of load unit R1 is connected to one end of the sampling resistor, and the second end of load unit R1 is connected to the first end of load unit R2 and the non-inverting input of the first operational amplifier. The first end of load unit R3 is connected to the other end of the sampling resistor, and the second end of load unit R3 is connected to the first end of load unit R4 and the non-inverting input of the second operational amplifier. The second ends of load unit R3 and load unit R4 are used to receive the common-mode voltage. The output end of the first operational amplifier and the first end of load unit R5 serve as the first output end, and the inverting input end of the first operational amplifier is connected to the second end of load unit R5 and the first end of load unit R6. The output end of the second operational amplifier and the first end of load unit R7 serve as the second output end, and the inverting input end of the second operational amplifier is connected to the second end of load unit R7 and the second end of load unit R6.

3. The bidirectional current detection circuit according to claim 2, characterized in that, The load units R1, R2, R3, and R4 have the same resistance value.

4. The bidirectional current detection circuit according to claim 2, characterized in that, The current direction comparison module includes: a third operational amplifier, a first inverter, and a second inverter; the non-inverting input of the third operational amplifier is connected to the output of the first operational amplifier, and the inverting input of the third operational amplifier is connected to the output of the second operational amplifier; the output of the third operational amplifier is connected to the input of the first inverter, and the output of the first inverter is connected to the input of the second inverter, the control terminal of the control switch SW2, and the control terminal of the control switch SW3, respectively; the output of the second inverter is connected to the control terminal of the control switch SW1 and the control terminal of the control switch SW4, respectively.

5. The bidirectional current detection circuit according to claim 4, characterized in that, The switched capacitor dynamic comparison module further includes: control switches SW5, SW6, SW7, SW8, SW9, and SW10; load units R8, R9, R10, and R11; the first terminal of load unit R8 is connected to the second terminal of control switch SW1, and the second terminal of load unit R8 is connected to the first terminal of control switch SW5; the first terminal of load unit R9 is connected to the first reference power supply, and the second terminal of load unit R9 is connected to the first terminal of control switch SW6; the second terminals of control switches SW5 and SW6 are respectively connected to the first terminal of the first capacitor; the second terminal of the first capacitor is... The first terminal of the control switch SW9 is connected to the inverting input terminal of the comparator; the first terminal of the load unit R11 is connected to the second terminal of the control switch SW3, and the second terminal of the load unit R11 is connected to the first terminal of the control switch SW8; the first terminal of the load unit R10 is connected to the second reference power supply, and the second terminal of the load unit R10 is connected to the first terminal of the control switch SW7; the second terminals of the control switches SW7 and SW8 are respectively connected to the first terminals of the second capacitor; the second terminal of the second capacitor is respectively connected to the first terminal of the control switch SW10 and the non-inverting input terminal of the comparator; the second terminal of the control switch SW9 is connected to the second terminal of the control switch SW10.

6. The bidirectional current detection circuit according to claim 5, characterized in that, The control terminals of control switches SW5, SW8, SW9, and SW10 are all connected to receive the same control signal.

7. The bidirectional current detection circuit according to claim 5, characterized in that, The control terminals of control switch SW6 and control switch SW7 are connected together to receive the same control signal.

8. The bidirectional current detection circuit according to claim 5, characterized in that, The comparator compares the voltages at its positive and negative terminals within a preset time period after the control switches SW6 and SW7 begin to close.

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