A current detection circuit based on h-bridge

Abstract

The application relates to a current detection circuit based on an H-bridge, comprising an H-bridge circuit and a current sampling and commutation circuit; the current sampling and commutation circuit is used for collecting the current flowing through the H-bridge circuit and comparing the current with a preset current threshold to control the commutation of the H-bridge circuit; a multistage amplification circuit is connected to the current sampling and commutation circuit and is used for multistage amplifying the collected current to obtain multistage amplified current; an MCU is used for providing the current sampling and commutation circuit with the preset current threshold and selecting the multistage amplified current in sections. The application carries out multistage amplification on weak current, effectively solves the pain points of low accuracy in a large range and weak signal in a small range in wide-range current sampling; the original current data are selected in sections, the peak current can be accurately detected, accurate basis is provided for the peak power output / input of a battery pack, and problems such as power overload and unstable motor power output caused by current detection errors are avoided.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more specifically to a current detection circuit based on an H-bridge. Background Technology

[0002] The core error in battery pack SOC estimation stems from current integration error; therefore, accurate detection of battery pack current is crucial for high-precision battery pack SOC estimation. However, current fluxgate current sensors based on H-bridge circuits for battery pack current detection have a full-scale, full-temperature (-40℃~85℃) accuracy of only 0.5%~1%, which cannot meet the requirements for high precision. Summary of the Invention

[0003] The present invention provides a current detection circuit based on an H-bridge to solve at least one of the above-mentioned technical problems.

[0004] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A current detection circuit based on an H-bridge, comprising:

[0005] The power supply end is used to connect to the power source.

[0006] An H-bridge circuit and a current sampling and commutation circuit are provided. One end of the H-bridge circuit is connected to the power supply terminal, and the other end of the H-bridge circuit is connected to the current sampling and commutation circuit. The current sampling and commutation circuit is connected to a preset current threshold. The current sampling and commutation circuit is used to collect the current flowing through the H-bridge circuit and compare it with the preset current threshold to control the commutation of the H-bridge circuit, thereby causing the H-bridge circuit to oscillate.

[0007] A multi-stage amplifier circuit, connected to the current sampling and commutation circuit, is used to amplify the current collected by the current sampling and commutation circuit in multiple stages to obtain a multi-stage amplified current.

[0008] The MCU is connected to the current sampling and commutation circuit and the multi-stage amplification circuit, and is used to provide the preset current threshold to the current sampling and commutation circuit, and to select the multi-stage amplification current segment.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the H-bridge circuit includes:

[0011] The first power transistor has its source connected to the power supply terminal;

[0012] The source of the second power transistor is connected to the power supply terminal;

[0013] The third power transistor has its drain connected to the drain of the second power transistor and its source connected to the current sampling and commutation circuit.

[0014] The fourth power transistor has its drain connected to the drain of the first power transistor, and its source connected to the current sampling and commutation circuit.

[0015] An inductor, one end of which is connected between the drain of the first power transistor and the drain of the fourth power transistor, and the other end of which is connected between the drain of the second power transistor and the drain of the third power transistor;

[0016] The first driving transistor has its source connected to the gate of the first power transistor and its drain connected to the drain of the second power transistor.

[0017] The second driving transistor has its source connected to the gate of the second power transistor and its drain connected to the drain of the first power transistor.

[0018] The third driving transistor has its source connected to the gate of the third power transistor and its drain connected to the drain of the fourth power transistor.

[0019] The fourth driving transistor has its source connected to the gate of the fourth power transistor and its drain connected to the drain of the third power transistor.

[0020] The first capacitor has one end connected to the power supply terminal and the other end connected to the gate of the first driving transistor and the gate of the second driving transistor.

[0021] The second capacitor has one end grounded and the other end connected to the gate of the third driving transistor and the gate of the fourth driving transistor.

[0022] Furthermore, the H-bridge circuit also includes:

[0023] The first TVS diode has its negative terminal connected to the power supply terminal and its positive terminal connected to the gate of the first driving transistor and the gate of the second driving transistor.

[0024] The second TVS diode has its positive terminal grounded and its negative terminal connected to the gate of the third driving transistor and the gate of the fourth driving transistor.

[0025] The first resistor is connected between the positive terminal of the first TVS diode and the negative terminal of the second TVS diode.

[0026] Furthermore, the first power transistor and the second power transistor are both PMOS transistors, and the third power transistor and the fourth power transistor are both NMOS transistors; the first driving transistor and the second driving transistor are both PMOS driving transistors, and the third driving transistor and the fourth driving transistor are both NMOS driving transistors.

[0027] Furthermore, the current sampling and commutation circuit includes:

[0028] The drain of the switching transistor is connected to the source of the third power transistor and the source of the fourth power transistor.

[0029] The second resistor has one end connected to the source of the switching transistor and the other end grounded.

[0030] The comparator has its inverting input connected to one end of the second resistor, its non-inverting input connected to the MCU to access the preset current threshold, and its output connected to the gate of the switching transistor.

[0031] Furthermore, the current sampling and commutation circuit also includes:

[0032] The third resistor is connected between one end of the second resistor and the inverting input of the comparator;

[0033] The fourth resistor has one end connected to the inverting input of the comparator and the other end grounded.

[0034] The fifth resistor is connected between the positive input terminal of the comparator and the MCU;

[0035] The sixth resistor has one end connected to the positive input terminal of the comparator and the other end grounded.

[0036] The third capacitor is connected in parallel with the sixth resistor.

[0037] Furthermore, the multi-stage amplifier circuit includes:

[0038] Bias reference circuit, used to provide bias and reference voltage;

[0039] The first-stage amplifier circuit is connected to the bias reference circuit and one end of the second resistor. It is used to amplify the current collected by the current sampling and commutation circuit in one stage under the action of the bias and reference voltage to obtain the first-stage amplified current.

[0040] The second-stage amplifier circuit is connected to the bias reference circuit and the first-stage amplifier circuit. It is used to amplify the first-stage amplifier current in two stages under the action of the bias and reference voltage to obtain the second-stage amplifier current.

[0041] The third-stage amplifier circuit is connected to the bias reference circuit and the second-stage amplifier circuit. It is used to amplify the first-stage amplified current in three stages under the action of the bias and reference voltage to obtain a third-stage amplified current.

[0042] Furthermore, the first-stage amplifier circuit includes:

[0043] The seventh resistor has one end connected to one end of the second resistor;

[0044] The first amplifier has its inverting input terminal connected to the other end of the seventh resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the first-stage amplification current.

[0045] The eighth resistor is connected between the inverting input terminal and the output terminal of the first amplifier;

[0046] The second-stage amplifier circuit includes:

[0047] The ninth resistor has one end connected to the output terminal of the first amplifier;

[0048] The second amplifier has its inverting input terminal connected to the other end of the ninth resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the second-stage amplification current.

[0049] The tenth resistor is connected between the inverting input and output terminals of the second amplifier.

[0050] The third-stage amplifier circuit includes:

[0051] The eleventh resistor is connected at one end to the output terminal of the first amplifier.

[0052] The third amplifier has its inverting input terminal connected to the other end of the eleventh resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the third-stage amplified current.

[0053] The twelfth resistor is connected between the inverting input and output of the third amplifier.

[0054] Furthermore, the bias reference circuit includes:

[0055] The thirteenth resistor has one end connected to the reference power supply.

[0056] The negative terminal of the third TVS diode is connected to the other end of the thirteenth resistor, and the positive terminal is grounded.

[0057] The fourth capacitor is connected in parallel to the third TVS diode;

[0058] The fourteenth resistor has one end connected to the other end of the thirteenth resistor, and the other end connected to the positive input terminal of the second amplifier and the positive input terminal of the third amplifier.

[0059] The fifteenth resistor has one end connected to the other end of the fourteenth resistor and the other end connected to the positive input terminal of the first amplifier.

[0060] The sixteenth resistor has one end connected to the other end of the fifteenth resistor, and the other end grounded.

[0061] Furthermore, the current range of the first-stage amplification current is ±200A to ±700A, the current range of the second-stage amplification current is ±20A to ±200A, and the current range of the third-stage amplification current is 0 to ±20A.

[0062] Specifically, the MCU is used to: take data values ​​in the range of 30% to 70% in both the high and low half-cycles when the current range is 0 to ±200A; and take data values ​​in the range of 33% to 50% in the high half-cycle and 50% to 70% in the low half-cycle when the current range is ±200A to ±700A.

[0063] The beneficial effects of this invention are as follows: The H-bridge-based current detection circuit of this invention performs multi-stage amplification for weak currents, effectively solving the pain points of low accuracy over a large range and weak signal over a small range in wide-range current sampling. This improves the current detection accuracy under all-temperature conditions by 0.2% to 0.7%, thus reducing the cumulative error of SOC integration during battery pack SOC estimation, thereby avoiding problems such as false charging, inaccurate range prediction, and low-charge drop-off, improving the range experience of new energy vehicles and the accuracy of power metering in energy storage stations. Simultaneously, this invention segments the raw current data, enabling precise detection of peak current, providing an accurate basis for the peak power output / input of the battery pack, and avoiding problems such as power overload and unstable motor power output caused by current detection errors. Attached Figure Description

[0064] Figure 1 This is a block diagram of a current detection circuit based on an H-bridge according to the present invention.

[0065] Figure 2 This is a schematic diagram of a current detection circuit based on an H-bridge according to the present invention;

[0066] Figure 3 The graph shows the full-range positive current test results at -40℃.

[0067] Figure 4 The graph shows the results of the full-range negative current test at -40℃.

[0068] Figure 5 The graph shows the full-range positive current test results at 25℃.

[0069] Figure 6 The graph shows the results of the full-range negative current test at 25℃.

[0070] Figure 7 The graph shows the full-range positive current test results at 85℃.

[0071] Figure 8 The graph shows the results of the full-range negative current test at 85℃.

[0072] Figure 9 This is an exploded structural diagram of a current detection device based on an H-bridge according to the present invention.

[0073] Figure 10This is an exploded structural diagram of a current detection system based on an H-bridge according to the present invention. Detailed Implementation

[0074] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0075] like Figure 1 As shown, an H-bridge-based current detection circuit includes:

[0076] The power supply end is used to connect to the power source.

[0077] An H-bridge circuit and a current sampling and commutation circuit are provided. One end of the H-bridge circuit is connected to the power supply terminal, and the other end of the H-bridge circuit is connected to the current sampling and commutation circuit. The current sampling and commutation circuit is connected to a preset current threshold. The current sampling and commutation circuit is used to collect the current flowing through the H-bridge circuit and compare it with the preset current threshold to control the commutation of the H-bridge circuit, thereby causing the H-bridge circuit to oscillate.

[0078] A multi-stage amplifier circuit, connected to the current sampling and commutation circuit, is used to amplify the current collected by the current sampling and commutation circuit in multiple stages to obtain a multi-stage amplified current.

[0079] The MCU is connected to the current sampling and commutation circuit and the multi-stage amplification circuit, and is used to provide the preset current threshold to the current sampling and commutation circuit, and to select the multi-stage amplification current segment.

[0080] In this preferred embodiment, such as Figure 2 As shown, the H-bridge circuit includes:

[0081] The source of the first power transistor Q1 is connected to the power supply terminal Vcc_40V;

[0082] The source of the second power transistor Q2 is connected to the power supply terminal Vcc_40V;

[0083] The third power transistor Q3 has its drain connected to the drain of the second power transistor Q2, and its source connected to the current sampling and commutation circuit.

[0084] The fourth power transistor Q4 has its drain connected to the drain of the first power transistor Q1, and its source connected to the current sampling and commutation circuit.

[0085] The inductor L has one end connected between the drain of the first power transistor Q1 and the drain of the fourth power transistor Q4, and the other end connected between the drain of the second power transistor Q2 and the drain of the third power transistor Q3.

[0086] The first driving transistor M1 has its source connected to the gate of the first power transistor Q1 and its drain connected to the drain of the second power transistor Q2.

[0087] The source of the second driving transistor M2 is connected to the gate of the second power transistor Q2, and the drain is connected to the drain of the first power transistor Q1.

[0088] The source of the third driving transistor M3 is connected to the gate of the third power transistor Q3, and the drain is connected to the drain of the fourth power transistor Q4.

[0089] The source of the fourth driving transistor M4 is connected to the gate of the fourth power transistor Q4, and the drain is connected to the drain of the third power transistor Q3.

[0090] The first capacitor C1 has one end connected to the power supply terminal Vcc_40V, and the other end connected to the gate of the first driving transistor M1 and the gate of the second driving transistor M2.

[0091] The second capacitor C2 has one end grounded to GND and the other end connected to the gate of the third driving transistor M3 and the gate of the fourth driving transistor M4.

[0092] Specifically, the first power transistor Q1 and the second power transistor Q2 are both PMOS transistors, and the third power transistor Q3 and the fourth power transistor Q4 are both NMOS transistors; the first driving transistor M1 and the second driving transistor M2 are both PMOS driving transistors, and the third driving transistor M3 and the fourth driving transistor M4 are both NMOS driving transistors. The first power transistor Q1, the second power transistor Q2, the third power transistor Q3, and the fourth power transistor Q4 form an H-bridge to carry high voltage and high current; wherein, the first power transistor Q1 and the second power transistor Q2 form the upper bridge arm, and the third power transistor Q3 and the fourth power transistor Q4 form the lower bridge arm. The first driving transistor M1, the second driving transistor M2, the third driving transistor M3, and the fourth driving transistor M4 form an H-bridge driving circuit to control the gates of the power transistors, respectively driving the first power transistor Q1, the second power transistor Q2, the third power transistor Q3, and the fourth power transistor Q4. The inductor L is the load, and the current cannot change abruptly, requiring a freewheeling path. The first capacitor C1 and the second capacitor C2 form a charging and discharging circuit to provide a variable gate voltage to the driving transistors.

[0093] In this invention, the H-bridge provides "saturation excitation": the magnetic core is made to work in the nonlinear magnetization region by alternating large current, which provides a prerequisite for magnetic field detection; the fluxgate completes "magnetic field-electrical signal conversion": the magnetic field to be measured is modulated into an induced signal by utilizing the magnetization asymmetry of the magnetic core.

[0094] In this preferred embodiment, such as Figure 2 As shown, the H-bridge circuit further includes:

[0095] The first TVS diode D1 has its negative terminal connected to the power supply terminal Vcc_40V, and its positive terminal connected to the gate of the first driving transistor M1 and the gate of the second driving transistor M2.

[0096] The second TVS transistor D2 has its positive terminal grounded to GND and its negative terminal connected to the gate of the third driving transistor M3 and the gate of the fourth driving transistor M4.

[0097] The first resistor R1 is connected between the positive terminal of the first TVS diode D1 and the negative terminal of the second TVS diode D2.

[0098] Specifically, the first TVS diode D1 and the second TVS diode D2 are the core components for voltage regulation and protection of the H-bridge power supply: they are used to provide a precise 40V voltage regulation for the high-power circuit through the Zener characteristics, ensuring the normal operation of the MOSFET, coil, and current sensor; they are also used to clamp the back electromotive force of the inductor and the overvoltage spikes caused by external surges, preventing the power devices from breaking down.

[0099] In this preferred embodiment, such as Figure 2 As shown, the current sampling and commutation circuit includes:

[0100] The drain of the switching transistor K is connected to the source of the third power transistor Q3 and the source of the fourth power transistor Q4.

[0101] The second resistor R2 is connected at one end to the source of the switching transistor K and at the other end to ground GND.

[0102] The comparator U0 has its inverting input connected to one end of the second resistor R2, its non-inverting input connected to the MCU to access the preset current threshold O_A_DACM, and its output connected to the gate of the switching transistor K.

[0103] Specifically, the second resistor R2 is a current sampling resistor. In this preferred embodiment, as shown... Figure 2 As shown, the current sampling and commutation circuit further includes:

[0104] The third resistor R3 is connected between one end of the second resistor R2 and the inverting input of the comparator U0;

[0105] The fourth resistor R4 is connected at one end to the inverting input of the comparator U0, and at the other end to ground (GND).

[0106] The fifth resistor R5 is connected between the positive input terminal of the comparator U0 and the MCU;

[0107] The sixth resistor R6 is connected at one end to the positive input terminal of the comparator U0, and at the other end to ground GND;

[0108] The third capacitor C3 is connected in parallel with the sixth resistor R6.

[0109] Specifically, the preset current threshold O_A_DACM is a current setting / feedback signal from the MCU, which is filtered by an RC network consisting of the fifth resistor R5, the sixth resistor R6, and the third capacitor C3, serving as the input reference for the entire circuit. The current detection process will be explained in detail below using the H-bridge circuit and the current sampling and commutation circuit:

[0110] Phase 1: The instant of power-on.

[0111] At the moment of power-on, due to the effect of the first capacitor C1 and the second capacitor C2, the gate voltages Vg of the first driving transistor M1 and the second driving transistor M2 of the PMOS are Vcc - 40V, and the gate voltages Vg of the third driving transistor M3 and the fourth driving transistor M4 of the NMOS are 0V. Therefore, the first driving transistor M1, the second driving transistor M2, the third driving transistor M3 and the fourth driving transistor M4 are all in the off state, which makes the first power transistor Q1, the second power transistor Q2, the third power transistor Q3 and the fourth power transistor Q4 of the H-bridge all in the off state.

[0112] Phase Two: Oscillation.

[0113] 1: The first capacitor C1 is slowly charged, the gate voltage of the first driving transistor M1 and the second driving transistor M2 decreases, and these two driving transistors begin to be "half-open", which in turn drives the first power transistor Q1 and the second power transistor Q2 to also be "half-open" - the first capacitor C1 is charged → the gate voltage of the first driving transistor M1 and the second driving transistor M2 decreases → gradually conduction.

[0114] 2: At the same time, the second capacitor C2 is charged, the gate voltage of the third driving transistor M3 and the fourth driving transistor M4 rises, causing the third driving transistor M3 and the fourth driving transistor M4 to be "half-open" - the second capacitor C2 is charged → the gate voltage of the third driving transistor M3 and the fourth driving transistor M4 rises → gradually turn on.

[0115] The driver transistor first enters the amplification region, which in turn causes the power transistor to conduct slightly.

[0116] 3: At this time, there is a slight difference in the voltage across the inductor L (which may be due to parasitic parameters or the initial bias of the circuit design). For example, the voltage at one end of the inductor L (the end connecting the drain of the first power transistor Q1 and the drain of the fourth power transistor Q4) is slightly higher.

[0117] 4 Key positive feedback: High voltage at one end of inductor L → the second power transistor Q2 is "closed tighter" through the second driver transistor M2, and the third power transistor Q3 is "opened wider" through the third driver transistor M3; Low voltage at the other end of inductor L → the first power transistor Q1 is "opened wider" through the first driver transistor M1, and the fourth power transistor Q4 is "closed tighter" through the fourth driver transistor M4.

[0118] 5. Results: The first power transistor Q1 and the third power transistor Q3 are fully turned on, while the second power transistor Q2 and the fourth power transistor Q4 are fully turned off. There is a current flowing from left to right in the coil of the inductor, and the "positive half-cycle" of oscillation begins.

[0119] The third stage: the positive half-cycle of the oscillation.

[0120] The H-bridge oscillation positive half-cycle conduction path is: first power transistor Q1 → inductor L → third power transistor Q3; the current path is: 40V power supply → first power transistor Q1 (upper bridge arm) → inductor L (left positive, right negative) → third power transistor Q3 (lower bridge arm) → current sampling resistor (second resistor R2) → GND (ground wire); at this time, the voltage across inductor L is left positive and right negative, which is close to the H-bridge supply voltage of 40V.

[0121] The inductor L stores energy like a "rechargeable battery". As the current gradually increases, the current sampling resistor detects the magnitude of the current and transmits it to the MCU (equivalent to the "brain" of the H-bridge) through a multi-stage amplification circuit.

[0122] Step 4: Reversal of H-bridge oscillation.

[0123] 1. Comparator U0 compares the current detected by the current sampling resistor with a preset current threshold;

[0124] 2. When the current in inductor L (i.e. the current detected by the current sampling resistor) rises to the "upper limit value (preset current threshold, such as 20A)" set by the MCU, the comparator U0 immediately outputs a command to turn off the switch K (the switch K is the "switch" for current sampling; after it is turned off, the detection of current in the current direction stops).

[0125] 3. An inductor is an inductive load, and the current cannot change abruptly. It will generate a "reverse electromotive force" (negative on the left and positive on the right) to maintain the original direction of the current.

[0126] 4. The reverse electromotive force generated by the inductor pushes the first power transistor Q1 and the third power transistor Q3 to cut off, while pulling the second power transistor Q2 and the fourth power transistor Q4 to conduct—completing the commutation, which is equivalent to the current direction "turning around".

[0127] Step 5: The negative half-cycle of the oscillation.

[0128] After the fourth step above, when the second power transistor Q2 and the fourth power transistor Q4 are turned on, while the first power transistor Q1 and the third power transistor Q3 are turned off, the voltage is applied across the inductor in a negative left and positive right direction. At this point, the oscillation enters the negative half-cycle.

[0129] Current path: 40V power supply → second power transistor Q2 (upper bridge arm) → inductor L (left negative, right positive) → fourth power transistor Q4 (lower bridge arm) → current sampling resistor → GND;

[0130] During the negative half-cycle of the H-bridge oscillation, the voltage across inductor L, which is negative on the left and positive on the right, gradually approaches 40V.

[0131] As the current gradually increases in the reverse direction, the current sampling resistor continues to detect it. When the current detected by the current sampling resistor rises to another "upper limit value", the comparator U0 will control the switching transistor K to activate, triggering the next commutation.

[0132] This cycle continues, and the H-bridge continuously outputs alternating current, providing a stable magnetic field for the fluxgate.

[0133] In this preferred embodiment, the multi-stage amplifier circuit includes:

[0134] Bias reference circuit, used to provide bias and reference voltage;

[0135] The first-stage amplifier circuit is connected to the bias reference circuit and one end of the second resistor R2. It is used to amplify the current collected by the current sampling and commutation circuit in one stage under the action of the bias and reference voltage to obtain the first-stage amplified current.

[0136] The second-stage amplifier circuit is connected to the bias reference circuit and the first-stage amplifier circuit. It is used to amplify the first-stage amplifier current in two stages under the action of the bias and reference voltage to obtain the second-stage amplifier current.

[0137] The third-stage amplifier circuit is connected to the bias reference circuit and the second-stage amplifier circuit. It is used to amplify the first-stage amplified current in three stages under the action of the bias and reference voltage to obtain a third-stage amplified current.

[0138] Specifically, the multi-stage amplification circuit ensures "detection accuracy": it amplifies weak induced signals through multiple stages, ensuring that the accuracy of current detection across the entire range is improved by 0.2% to 0.7%.

[0139] In this preferred embodiment, such as Figure 2 As shown, the first-stage amplifier circuit includes:

[0140] The seventh resistor R7 is connected at one end to one end of the second resistor R2;

[0141] The first amplifier U1 has its inverting input terminal connected to the other end of the seventh resistor R7, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the first-stage amplification current I_A_OUT1.

[0142] The eighth resistor R8 is connected between the inverting input terminal and the output terminal of the first amplifier U1;

[0143] The second-stage amplifier circuit includes:

[0144] The ninth resistor R9 is connected at one end to the output terminal of the first amplifier U1;

[0145] The second amplifier U2 has its inverting input terminal connected to the other end of the ninth resistor R9, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the second-stage amplification current I_A_OUT2.

[0146] The tenth resistor R10 is connected between the inverting input terminal and the output terminal of the second amplifier U2;

[0147] The third-stage amplifier circuit includes:

[0148] The eleventh resistor R11 is connected at one end to the output terminal of the first amplifier U1.

[0149] The third amplifier U3 has its inverting input terminal connected to the other end of the eleventh resistor R11, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the third-stage amplification current I_A_OUT3.

[0150] The twelfth resistor R12 is connected between the inverting input terminal and the output terminal of the third amplifier U3.

[0151] Specifically, the first amplifier U1 further amplifies or buffers the processed current signal and outputs a first-stage amplified current I_A_OUT1 to the MCU for precise current monitoring. The output terminal of the first amplifier U1 serves as a test point and can output the corresponding voltage values ​​under different currents (e.g., +700A: 0.236V, -700A: 3.064V).

[0152] The second amplifier U2 further amplifies or buffers the processed current signal and outputs the secondary amplified current I_A_OUT2 to the MCU for precise current monitoring. The output of the second amplifier U2 serves as a test point and can output the corresponding voltage value under different currents (e.g., -200A: 0.305V, +200A: 2.995V).

[0153] The third-stage amplifier circuit provides another current signal output, which can be used for redundant monitoring or different control loops. The third amplifier U3 further amplifies or buffers the processed current signal, outputting the three-stage amplified current I_A_OUT3 to the MCU for precise current monitoring. The output of the third amplifier U3 serves as a test point, capable of outputting corresponding voltage values ​​under different currents (e.g., +20A: 3.000V, -20A: 0.303V). In this preferred embodiment, as shown... Figure 2 As shown, the bias reference circuit includes:

[0154] The thirteenth resistor, R13, is connected at one end to the reference power supply Vcc_5V;

[0155] The negative terminal of the third TVS diode D3 is connected to the other end of the thirteenth resistor R13, and the positive terminal is grounded to GND.

[0156] The fourth capacitor C4 is connected in parallel to the third TVS transistor D3;

[0157] The fourteenth resistor R14 is connected at one end to the other end of the thirteenth resistor R13, and at the other end to the positive input terminal of the second amplifier U2 and the positive input terminal of the third amplifier U3.

[0158] The fifteenth resistor R15 is connected at one end to the other end of the fourteenth resistor R14, and at the other end to the positive input terminal of the first amplifier U1.

[0159] The sixteenth resistor R16 has one end connected to the other end of the fifteenth resistor R15, and the other end is grounded (GND).

[0160] Specifically, the current generated by the thirteenth resistor R13, the third TVS diode D3, and the fourth capacitor C4 produces a stable reference voltage VREF. After being divided by the fourteenth resistor R14, the fifteenth resistor R15, and the sixteenth resistor R16, the reference voltage VREF provides bias and comparison reference for the subsequent amplifier.

[0161] In addition, in the H-bridge-based current detection circuit of this invention, the output of comparator U0 is also connected to the MCU to feed back the H-bridge commutation capture interrupt I_F_CMP_OP / M to the MCU; the output of comparator U0 is also connected to the MCU through the seventeenth resistor R17, and the MCU outputs the H-bridge commutation power transistor cycle capture monitoring signal O_S_CmpPU / M to the current sampling and commutation circuit. One end of inductor L is connected to the MCU through the eighteenth resistor R18, the fifth capacitor C5, and the nineteenth resistor R19 connected in series, to feed back the second H-bridge oscillation period signal I_F_Coil2 / M to the MCU. The fifth capacitor C5 and the nineteenth resistor R19 are connected to ground (GND) through the twentieth resistor R20. The other end of inductor L is connected to the MCU through the twenty-first resistor R21, the sixth capacitor C6, and the twenty-second resistor R22 connected in series, to feed back the first H-bridge oscillation period signal I_F_Coil1 / M to the MCU. The sixth capacitor C6 and the twenty-second resistor R22 are connected to ground (GND) through the twenty-third resistor R23.

[0162] In this preferred embodiment, the current range of the first-stage amplification current I_A_OUT1 is ±200A~±700A, the current range of the second-stage amplification current I_A_OUT2 is ±20A~±200A, and the current range of the third-stage amplification current I_A_OUT3 is 0~±20A.

[0163] Specifically, the MCU is used to: take data values ​​in the range of 30% to 70% in both the high and low half-cycles when the current range is 0 to ±200A; and take data values ​​in the range of 33% to 50% in the high half-cycle and 50% to 70% in the low half-cycle when the current range is ±200A to ±700A.

[0164] Specifically, the first-stage amplifier circuit amplifies the signal by 3 times, and the current range of the first-stage amplification current I_A_OUT1 is ±200A to ±700A; the second-stage amplifier circuit amplifies the signal by 10 times, and the current range of the second-stage amplification current I_A_OUT2 is ±20A to ±200A; the third-stage amplifier circuit amplifies the signal by 101 times, and the current range of the third-stage amplification current I_A_OUT3 is 0 to ±20A.

[0165] The relationship between the primary current (measured current) Ip and the secondary induced voltage is: Vsens = Ip * R² / Ns

[0166] Among them, the current sampling resistor (second resistor R2): R2=1Ω, and the number of coil turns Ns: 2000;

[0167] First-stage amplification voltage Vout1: First-stage amplification current I_A_OUT1 amplifies the voltage across the current sampling resistor by 3 times: Vout1 = 0.504*VREF - 3.03*Vsense;

[0168] Second-stage amplification voltage Vout2: Vout2 = 0.506*VREF + 10.09*Vsense;

[0169] The third-stage amplification voltage Vout3 is: Vout3 = 0.5*VREF + 101*Vsense;

[0170] Vsens is the voltage across the current sampling resistor (second resistor R2); VREF is the reference voltage of 3.3V.

[0171] To ensure a current detection accuracy of 0.3% across the entire measurement range, the raw current data is segmented and calculated as follows:

[0172] Ip: 0~±200A: The high and low half-cycles of the oscillation are both taken from the range of 30%~70% of the data value;

[0173] Ip: ±200A~±700A: For the high half-cycle, take the data value in the range of 33%~50%; for the low half-cycle, take the data value in the range of 50%~70%.

[0174] In this embodiment, the current test results under full temperature environment (-40~85℃) and full range (0~±700A) are as follows: Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown.

[0175] Based on the above-described H-bridge-based current detection circuit, the present invention also provides an H-bridge-based current detection device, such as... Figure 9 As shown, the current detection device includes:

[0176] The upper cover 1 and the lower cover 2 are closed to form an accommodating space, and the lower cover 2 is provided with an embedded ring 3;

[0177] A magnetic core 4 and a coil 5, wherein the coil 5 is wound around the magnetic core 4 to form an inductor, and the inductor is mounted in the receiving space by a bracket 6;

[0178] PCB board 7 is disposed in the accommodating space, on which the H-bridge based current detection circuit (excluding inductor and MCU) as described above is integrated, and a connector terminal cover 8 (which is a pin connector, an interface for external communication) is configured and connected to the inductor.

[0179] Among them, the inductor, PCB board 7 and connector terminal film 8 are finally encapsulated in the housing space by encapsulating glue 9.

[0180] Based on the aforementioned H-bridge-based current detection circuit, this invention also provides an H-bridge-based current detection system, such as... Figure 10 As shown, the current detection system is used to detect the current of the vehicle's power module, and includes a power supply subsystem, an MCU subsystem, a communication subsystem, and a current detection subsystem. The power supply subsystem is connected to the vehicle's power module and is used to convert the electrical energy provided by the vehicle's power module into 3.3V, 5V, and 40V power supplies. The MCU subsystem includes an MCU. The current detection subsystem includes the H-bridge-based current detection circuit described above (excluding the MCU). The power supply subsystem supplies power to the MCU subsystem, the communication subsystem, and the current detection subsystem. Under the control of the MCU subsystem, the current detection subsystem detects the current of the vehicle's power module and transmits the detection result to the MCU subsystem, and communicates with an external bus through the communication subsystem.

[0181] This invention employs multi-stage amplification for weak currents, effectively addressing the pain points of low accuracy over large ranges and weak signals over small ranges in wide-range current sampling. This improves the accuracy of current detection under all operating temperatures by 0.2% to 0.7%, thereby reducing the cumulative error of SOC integration during battery pack SOC estimation. This helps avoid problems such as false charging, inaccurate range prediction, and low-charge drop-offs, improving the driving experience of new energy vehicles and the accuracy of power metering in energy storage stations. Furthermore, this invention segments the raw current data, enabling precise detection of peak current and providing accurate data for peak power output / input of the battery pack. This avoids problems such as power overload and unstable motor power output caused by current detection errors.

[0182] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A current detection circuit based on an H-bridge, characterized in that, include: The power supply end is used to connect to the power source. An H-bridge circuit and a current sampling and commutation circuit are provided. One end of the H-bridge circuit is connected to the power supply terminal, and the other end of the H-bridge circuit is connected to the current sampling and commutation circuit. The current sampling and commutation circuit is connected to a preset current threshold. The current sampling and commutation circuit is used to collect the current flowing through the H-bridge circuit and compare it with the preset current threshold to control the commutation of the H-bridge circuit, thereby causing the H-bridge circuit to oscillate. A multi-stage amplifier circuit, connected to the current sampling and commutation circuit, is used to amplify the current collected by the current sampling and commutation circuit in multiple stages to obtain a multi-stage amplified current. The MCU is connected to the current sampling and commutation circuit and the multi-stage amplification circuit, and is used to provide the preset current threshold to the current sampling and commutation circuit, and to select the multi-stage amplification current segment.

2. The current detection circuit based on an H-bridge according to claim 1, characterized in that, The H-bridge circuit includes: The first power transistor has its source connected to the power supply terminal; The source of the second power transistor is connected to the power supply terminal; The third power transistor has its drain connected to the drain of the second power transistor and its source connected to the current sampling and commutation circuit. The fourth power transistor has its drain connected to the drain of the first power transistor, and its source connected to the current sampling and commutation circuit. An inductor, one end of which is connected between the drain of the first power transistor and the drain of the fourth power transistor, and the other end of which is connected between the drain of the second power transistor and the drain of the third power transistor; The first driving transistor has its source connected to the gate of the first power transistor and its drain connected to the drain of the second power transistor. The second driving transistor has its source connected to the gate of the second power transistor and its drain connected to the drain of the first power transistor. The third driving transistor has its source connected to the gate of the third power transistor and its drain connected to the drain of the fourth power transistor. The fourth driving transistor has its source connected to the gate of the fourth power transistor and its drain connected to the drain of the third power transistor. The first capacitor has one end connected to the power supply terminal and the other end connected to the gate of the first driving transistor and the gate of the second driving transistor. The second capacitor has one end grounded and the other end connected to the gate of the third driving transistor and the gate of the fourth driving transistor.

3. The current detection circuit based on an H-bridge according to claim 2, characterized in that, The H-bridge circuit also includes: The first TVS diode has its negative terminal connected to the power supply terminal and its positive terminal connected to the gate of the first driving transistor and the gate of the second driving transistor. The second TVS diode has its positive terminal grounded and its negative terminal connected to the gate of the third driving transistor and the gate of the fourth driving transistor. The first resistor is connected between the positive terminal of the first TVS diode and the negative terminal of the second TVS diode.

4. The current detection circuit based on an H-bridge according to claim 2, characterized in that, The first power transistor and the second power transistor are both PMOS transistors, and the third power transistor and the fourth power transistor are both NMOS transistors; the first driving transistor and the second driving transistor are both PMOS driving transistors, and the third driving transistor and the fourth driving transistor are both NMOS driving transistors.

5. The current detection circuit based on an H-bridge according to claim 2, characterized in that, The current sampling and commutation circuit includes: The drain of the switching transistor is connected to the source of the third power transistor and the source of the fourth power transistor. The second resistor has one end connected to the source of the switching transistor and the other end grounded. The comparator has its inverting input connected to one end of the second resistor, its non-inverting input connected to the MCU to access the preset current threshold, and its output connected to the gate of the switching transistor.

6. The current detection circuit based on an H-bridge according to claim 5, characterized in that, The current sampling and commutation circuit also includes: The third resistor is connected between one end of the second resistor and the inverting input of the comparator; The fourth resistor has one end connected to the inverting input of the comparator and the other end grounded. The fifth resistor is connected between the positive input terminal of the comparator and the MCU; The sixth resistor has one end connected to the positive input terminal of the comparator and the other end grounded. The third capacitor is connected in parallel with the sixth resistor.

7. The current detection circuit based on an H-bridge according to claim 5, characterized in that, The multi-stage amplifier circuit includes: Bias reference circuit, used to provide bias and reference voltage; The first-stage amplifier circuit is connected to the bias reference circuit and one end of the second resistor. It is used to amplify the current collected by the current sampling and commutation circuit in one stage under the action of the bias and reference voltage to obtain the first-stage amplified current. The second-stage amplifier circuit is connected to the bias reference circuit and the first-stage amplifier circuit. It is used to amplify the first-stage amplifier current in two stages under the action of the bias and reference voltage to obtain the second-stage amplifier current. The third-stage amplifier circuit is connected to the bias reference circuit and the second-stage amplifier circuit. It is used to amplify the first-stage amplified current in three stages under the action of the bias and reference voltage to obtain a third-stage amplified current.

8. The current detection circuit based on an H-bridge according to claim 7, characterized in that, The first stage amplifier circuit includes: The seventh resistor has one end connected to one end of the second resistor; The first amplifier has its inverting input terminal connected to the other end of the seventh resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the first-stage amplification current. The eighth resistor is connected between the inverting input terminal and the output terminal of the first amplifier; The second-stage amplifier circuit includes: The ninth resistor has one end connected to the output terminal of the first amplifier; The second amplifier has its inverting input terminal connected to the other end of the ninth resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the second-stage amplification current. The tenth resistor is connected between the inverting input and output terminals of the second amplifier. The third-stage amplifier circuit includes: The eleventh resistor is connected at one end to the output terminal of the first amplifier. The third amplifier has its inverting input terminal connected to the other end of the eleventh resistor, its non-inverting input terminal connected to the bias reference circuit, and its output terminal outputting the third-stage amplified current. The twelfth resistor is connected between the inverting input and output of the third amplifier.

9. The current detection circuit based on an H-bridge according to claim 8, characterized in that, The bias reference circuit includes: The thirteenth resistor has one end connected to the reference power supply. The negative terminal of the third TVS diode is connected to the other end of the thirteenth resistor, and the positive terminal is grounded. The fourth capacitor is connected in parallel to the third TVS diode; The fourteenth resistor has one end connected to the other end of the thirteenth resistor, and the other end connected to the positive input terminal of the second amplifier and the positive input terminal of the third amplifier. The fifteenth resistor has one end connected to the other end of the fourteenth resistor and the other end connected to the positive input terminal of the first amplifier. The sixteenth resistor has one end connected to the other end of the fifteenth resistor, and the other end grounded.

10. The current detection circuit based on an H-bridge according to claim 7, characterized in that, The current range of the first-stage amplification current is ±200A to ±700A, the current range of the second-stage amplification current is ±20A to ±200A, and the current range of the third-stage amplification current is 0 to ±20A. Specifically, the MCU is used to: take data values ​​in the range of 30% to 70% in both the high and low half-cycles when the current range is 0 to ±200A; and take data values ​​in the range of 33% to 50% in the high half-cycle and 50% to 70% in the low half-cycle when the current range is ±200A to ±700A.

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