Current sampling circuit and system and vehicle

Abstract

The utility model relates to a current sampling circuit and system and a vehicle. The current sampling circuit is used for current sampling of a front sampling circuit (101) and comprises a first operational amplifier circuit (102), a second operational amplifier circuit (103) and a controller (104), the first input end of the first operational amplifier circuit is suitable for being connected with the front sampling circuit, and the first output end is connected with the second input end of the second operational amplifier circuit and the controller; the second output end of the second operational amplifier circuit is connected with the controller; the controller is suitable for determining the sampling current value of the front sampling circuit according to the received electric signals output by the first operational amplifier circuit and the second operational amplifier circuit, so that the sampling current value of the to-be-tested device can be obtained, and the current sampling values of different operational amplifier circuits are applied to current feedback according to different working conditions of the to-be-tested device. The overall reliable and efficient operation of the to-be-tested device control system is ensured; meanwhile, when the current range of the front sampling circuit is small, the precision of a current sampling value is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of current sampling, and in particular, to a current sampling circuit, system and vehicle. Background Art

[0002] Current sampling refers to the collection and processing of current signals. Through current sampling, real-time monitoring and control of the operating status of the device under test can be achieved, thereby ensuring the stable operation of the device under test. Specifically, current sampling can be performed on the pre-sampling circuit connected to the device under test, and the sampling current value of the device under test can be determined by the sampling current value of the pre-sampling circuit.

[0003] However, the current sampling range of a high-power device under test is relatively wide. When the device under test is operating under low-power conditions, the corresponding working current is relatively small, resulting in a certain error between the sampled current value and the actual current value. The accuracy of current sampling is relatively low, which in turn affects the control performance of the device under low torque. Utility Model Content

[0004] The purpose of the present disclosure is to provide a current sampling circuit, system and vehicle, aiming to solve the above-mentioned technical problems.

[0005] In order to achieve the above object, the present disclosure provides a current sampling circuit for current sampling of a pre-sampling circuit, characterized in that it includes:

[0006] A first operational amplifier circuit, a second operational amplifier circuit and a controller;

[0007] Wherein, the first input end of the first operational amplifier circuit is suitable for connecting to the pre-sampling circuit, and the first output end of the first operational amplifier circuit is connected to the second input end of the second operational amplifier circuit and the controller respectively;

[0008] The second output terminal of the second operational amplifier circuit is connected to the controller;

[0009] The controller is adapted to determine the sampling current value of the pre-sampling circuit according to the received electrical signals output by the first operational amplifier circuit and the second operational amplifier circuit.

[0010] Optionally, the first input terminal of the first operational amplifier circuit includes: a first non-inverting input terminal and a first inverting input terminal; wherein the first non-inverting input terminal is connected to a first reference voltage, and the first inverting input terminal is suitable for being connected to the pre-sampling circuit;

[0011] The second input terminal of the second operational amplifier circuit includes: a second non-inverting input terminal and a second inverting input terminal; wherein the second non-inverting input terminal is connected to a second reference voltage, and the second inverting input terminal is connected to the first output terminal of the first operational amplifier circuit.

[0012] Optionally, the current sampling circuit further includes: a reference voltage generating circuit, wherein the reference voltage generating circuit is used to generate the first reference voltage and / or the second reference voltage;

[0013] The reference voltage generating circuit comprises:

[0014] A first operational amplifier, a second resistor, a third resistor, a fourth resistor and a first capacitor;

[0015] Wherein, one end of the second resistor is connected to the divided voltage, and the other end is used to be connected to one end of the third resistor and the non-inverting input end of the first operational amplifier respectively;

[0016] The other end of the third resistor is grounded;

[0017] The first operational amplifier has a first power supply terminal connected to ground, a second power supply terminal connected to a divided voltage, and an inverting input terminal and an output terminal respectively connected to one end of the fourth resistor;

[0018] The other end of the fourth resistor is used to be connected to one end of the first capacitor and connected to the first non-inverting input end of the first operational amplifier circuit through the first resistor; or the other end of the fourth resistor is used to be connected to one end of the first capacitor and connected to the second non-inverting input end of the second operational amplifier circuit;

[0019] The other end of the first capacitor is grounded.

[0020] Optionally, the first operational amplifier circuit includes:

[0021] a second operational amplifier, a first feedback resistor, a second feedback resistor, a third feedback resistor, a fourth feedback resistor, and a fifth resistor;

[0022] Wherein, the second operational amplifier, the inverting input terminal is used to be connected to one end of the first feedback resistor and one end of the second feedback resistor respectively, the non-inverting input terminal is used to be connected to one end of the third feedback resistor and one end of the fourth feedback resistor respectively, the output terminal is used to be connected to the other end of the second feedback resistor and one end of the fifth resistor respectively, the first power supply terminal is grounded, and the second power supply terminal is connected to the divided voltage;

[0023] The other end of the first feedback resistor is used to be connected to the pre-sampling circuit;

[0024] The other end of the third feedback resistor is grounded;

[0025] The other end of the fourth feedback resistor is connected to the reference voltage;

[0026] The other end of the fifth resistor is used to be connected to the ground line, the second input end of the second operational amplifier circuit and the controller respectively.

[0027] Optionally, the first operational amplifier circuit further includes:

[0028] A second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor;

[0029] Wherein, one end of the second capacitor is used to be connected to the other end of the first feedback resistor, and the other end is used to be connected to the other end of the third feedback resistor;

[0030] The third capacitor is connected in parallel with the second feedback resistor;

[0031] The fourth capacitor is connected in parallel with the fourth feedback resistor;

[0032] The fifth capacitor is connected in series with the fifth resistor and is grounded.

[0033] Optionally, the second operational amplifier circuit includes:

[0034] a third operational amplifier, a fifth feedback resistor, a sixth feedback resistor, a seventh feedback resistor, and a sixth resistor;

[0035] Wherein, the third operational amplifier, the inverting input terminal is used to be connected to one end of the fifth feedback resistor and one end of the sixth feedback resistor respectively, the non-inverting input terminal is used to be connected to one end of the seventh feedback resistor, the output terminal is used to be connected to the other end of the sixth feedback resistor and one end of the sixth resistor respectively, the first power supply terminal is grounded, and the second power supply terminal is connected to the divided voltage;

[0036] The other end of the fifth feedback resistor is used to be connected to the first output end of the first operational amplifier circuit;

[0037] The other end of the seventh feedback resistor is connected to the reference voltage;

[0038] The other end of the sixth resistor is used to be connected to the ground wire and the controller respectively.

[0039] Optionally, the second operational amplifier circuit further includes:

[0040] a sixth capacitor and a seventh capacitor;

[0041] Wherein, the sixth capacitor is connected in parallel with the sixth feedback resistor;

[0042] The seventh capacitor is connected in series with the sixth resistor and is grounded.

[0043] Optionally, the pre-sampling circuit is further included, which is used for current sampling of the driving motor, and the pre-sampling circuit includes:

[0044] A first power MOS tube, a second power MOS tube and a sampling resistor;

[0045] Wherein, the first end of the first power MOS tube is used to be connected to the power supply, and the second end is used to be connected to the first end of the second power MOS tube and the output end of the driving motor respectively;

[0046] The second end of the second power MOS tube is connected to the first input end of the first operational amplifier circuit and one end of the sampling resistor;

[0047] The other end of the sampling resistor is grounded.

[0048] Optionally, the sampling resistor is an extremely low resistance high precision alloy resistor.

[0049] In addition, to achieve the above objectives, the present disclosure also provides a current sampling system, including:

[0050] A current sampling circuit, wherein the current sampling circuit is the above-mentioned current sampling circuit.

[0051] In addition, to achieve the above objectives, the present disclosure also provides a vehicle, including the above current sampling system.

[0052] In the above technical scheme, the current sampling circuit includes a first operational amplifier circuit, a second operational amplifier circuit and a controller, and the first input end of the first operational amplifier circuit is suitable for connecting to the pre-sampling circuit, and the first output end is connected to the second input end of the second operational amplifier circuit and the controller respectively; the second output end of the second operational amplifier circuit is connected to the controller; the controller is suitable for determining the sampling current value of the pre-sampling circuit according to the received electrical signals output by the first operational amplifier circuit and the second operational amplifier circuit, and then the sampling current value of the device under test can be known; in this way, the controller can apply the current sampling value of the first operational amplifier circuit or the second operational amplifier circuit to the current feedback of the device under test according to the different working conditions of the device under test, which can ensure the overall reliable and efficient operation of the control system of the device under test; at the same time, when the device under test is running at low power and the current range is small, the accuracy of the current sampling value can be improved, avoiding the high performance requirements of the operational amplifier using only a first-stage operational amplifier circuit. In addition, compared with the use of Hall sensors to sample the current of the device under test, the current sampling circuit disclosed in the present invention has low cost and occupies little space.

[0053] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0055] Figure 1 It is a structural schematic diagram of a current sampling system according to an exemplary embodiment.

[0056] Figure 2 The figure is a connection diagram of a pre-sampling circuit according to an exemplary embodiment.

[0057] Figure 3 is a connection diagram of a first operational amplifier circuit according to an exemplary embodiment.

[0058] Figure 4 is a connection diagram of a second operational amplifier circuit according to an exemplary embodiment.

[0059] Figure 5 It is a structural schematic diagram of a current sampling circuit according to an exemplary embodiment.

[0060] Figure 6 The figure is a connection diagram of a reference voltage generating circuit according to an exemplary embodiment.

[0061] Description of Reference Numerals

[0062] 100 Current sampling circuit 101 Pre-sampling circuit

[0063] 102 first operational amplifier circuit 103 second operational amplifier circuit

[0064] 104 controller 200 drive motor

[0065] 105 Reference voltage generating circuit R1 First resistor

[0066] U1 1st operational amplifier R2 2nd resistor

[0067] R3 The third resistor R4 The fourth resistor

[0068] C1 First capacitor U2 Second operational amplifier

[0069] Rf1 First feedback resistor Rf2 Second feedback resistor

[0070] Rf3 The third feedback resistor Rf4 The fourth feedback resistor

[0071] R5 Fifth resistor C2 Second capacitor

[0072] C3 Third capacitor C4 Fourth capacitor

[0073] C5 Fifth capacitor U3 Third operational amplifier

[0074] Rf5 The fifth feedback resistor Rf6 The sixth feedback resistor

[0075] Rf7 seventh feedback resistor R6 sixth resistor

[0076] C6 Sixth capacitor C7 Seventh capacitor

[0077] Q1 The first power MOS tube Q2 The second power MOS tube

[0078] Rc1 sampling resistor DETAILED DESCRIPTION

[0079] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0080] Current sampling refers to the collection and processing of current signals. Through current sampling, real-time monitoring and control of the operating status of the device under test can be achieved, thereby ensuring the stable operation of the device under test. The following embodiments are all described with the device under test being a drive motor as an example. The current sampling range of a high-power drive motor is relatively wide. When the drive motor is running under low operating conditions, the corresponding working current is relatively small, resulting in a certain error between the sampled current value and the actual current value. The accuracy of current sampling is relatively low, which in turn affects the control performance of the drive motor under low torque.

[0081] Related technologies usually use the following methods to sample the current of the drive motor:

[0082] Method 1: Use Hall sensor to sample the output current of the drive motor. However, the larger the current sampling range, the larger the corresponding voltage, which leads to a larger design cost and occupied volume of the Hall sensor, and does not meet the high power density design requirements of the drive motor.

[0083] Method 2: Sample the output current of the drive motor through a sampling resistor, that is, measure the electrical signal of the sampling resistor, amplify it through the operational amplifier and input it into the controller, and the controller analyzes the sampled current. However, when the current sampling range is wide, the corresponding voltage is high, and the heat generated by the sampling resistor is large, which affects the overall heat dissipation of the current sampling system. In addition, when the drive motor runs at low power, the current value is small, and the performance requirements of the operational amplifier are high, which is difficult to meet the accuracy requirements of current sampling.

[0084] To this end, the present disclosure provides a current sampling circuit, a system and a vehicle. The specific implementation methods of the present disclosure are described in detail below with reference to the accompanying drawings.

[0085] Since the drive motor can usually be a three-phase motor, that is, an AC motor driven by three-phase AC power, the three phases specifically include U, V, and W, and the interval between each phase is 120 degrees electrical angle. When the three-phase AC power is passed, the drive motor will generate a rotating magnetic field, and the rotating magnetic field cuts the rotor winding to generate electricity. The present disclosure is provided with a corresponding current sampling circuit with the same structure for each phase of the drive motor. In order to reduce repeated descriptions and drawings, in the following embodiments and drawings, only one of the current sampling circuits of one phase is exemplified, and the letter N is used to represent the specific phase, that is, N can be any one of U, V, and W.

[0086] Figure 1 FIG. 1 is a schematic diagram showing a structure of a current sampling system according to an exemplary embodiment. Figure 1 As shown, the present disclosure provides a current sampling circuit for current sampling of a pre-sampling circuit 101 . The current sampling circuit 100 includes: a first operational amplifier circuit 102 , a second operational amplifier circuit 103 and a controller 104 .

[0087] Among them, the first input end of the first operational amplifier circuit 102 is suitable for connecting to the pre-sampling circuit 101, and the first output end of the first operational amplifier circuit 102 is respectively connected to the second input end of the second operational amplifier circuit 103 and the controller 104; the second output end of the second operational amplifier circuit 103 is connected to the controller 104; the controller 104 is suitable for determining the sampling current value of the pre-sampling circuit 101 according to the received electrical signals output by the first operational amplifier circuit 102 and the second operational amplifier circuit 103.

[0088] In the present disclosure, the controller 104 may be a microcontroller unit (MCU). When the circuit starts running, the electric signal generated by the pre-sampling circuit 101 is amplified by the first operational amplifier circuit 102 and transmitted to the second operational amplifier circuit 103 and the controller 104. The second operational amplifier circuit 103 amplifies the electric signal amplified by the first operational amplifier circuit 102 again and transmits it to the controller 104. That is, the controller 104 can receive the electric signal amplified once by the first operational amplifier circuit 102 and the electric signal amplified twice by the second operational amplifier circuit 103. Then, the controller 104 converts the electric signal through information processing to obtain the current sampling value of the pre-sampling circuit 101. The current sampling value is equivalent to the current sampling value of the drive motor 200 connected to the pre-sampling circuit 101. The controller 104 can switch the operational amplifier circuit according to the current sampling value, and apply the first operational amplifier circuit 102 or the second operational amplifier circuit 103 to the current feedback of the drive motor 200 to ensure the current sampling accuracy under different working conditions of the drive motor 200.

[0089] In addition, if Figure 1 As shown, since the drive motor 200 is an AC motor, its electrical signal is an AC signal with positive and negative values, and the controller 104 usually cannot read negative values, so it is necessary to set a reference voltage Vref to raise the voltage, wherein the size of the reference voltage Vref can be set according to the actual conditions of each component, for example, it can be 2.5V.

[0090] It is worth noting that the above-mentioned current sampling circuit 100 does not involve method improvement, but is implemented by relying on circuit structure and conventional application of simple programs or known computer programs. For example, the sampling range of the first operational amplifier circuit 102 can be set to [-500A, -200A) and (+200A, +500A], and the sampling range of the second operational amplifier circuit 103 can be set to [-200A, +200A]. When the current sampling value obtained by the controller 104 is relatively large, for example, +400A, and is within the sampling range of the first operational amplifier circuit 102, the controller 104 uses the current sampling value of the first operational amplifier circuit 102 to drive the current feedback of the motor 200; if the current sampling value obtained by the controller 104 is relatively small, for example, +120A, and is within the sampling range of the second operational amplifier circuit 103, the controller 104 uses the current sampling value of the second operational amplifier circuit 103 to drive the current feedback of the motor 200; in this way, for different operating conditions of the drive motor, by selecting operational amplifier circuits with different amplification precisions, the operating state of the drive motor is monitored and controlled in real time to ensure the stable operation of the drive motor.

[0091] In the above technical solution, the current sampling circuit 100 includes a first operational amplifier circuit 102, a second operational amplifier circuit 103 and a controller 104, and the first input end of the first operational amplifier circuit 102 is suitable for being connected to the pre-sampling circuit 101, and the first output end is respectively connected to the second input end of the second operational amplifier circuit 103 and the controller 104; the second output end of the second operational amplifier circuit 103 is connected to the controller 104; the controller 104 is suitable for determining the sampling current value of the pre-sampling circuit 101 according to the received electrical signals output by the first operational amplifier circuit 102 and the second operational amplifier circuit 103. The current sampling value is equivalent to the current sampling value of the drive motor 200 connected to the pre-sampling circuit 101. In this way, the controller 104 can apply the current sampling value of the first operational amplifier circuit 102 or the second operational amplifier circuit 103 to the current feedback of the drive motor 200 according to the different working conditions of the drive motor 200, which can ensure the reliable and efficient operation of the drive motor control system as a whole; at the same time, when the drive motor 200 is running at low power and the current range is small, the accuracy of the current sampling value can be improved, avoiding the high performance requirements of the operational amplifier using only a first-stage operational amplifier circuit. In addition, compared with the use of Hall sensors for current sampling, the current sampling circuit disclosed in the present invention has a lower cost and occupies less space.

[0092] Figure 2 FIG. 1 is a connection diagram of a pre-sampling circuit according to an exemplary embodiment. Figure 2 As shown, as an optional implementation, the current sampling circuit 100 further includes a pre-sampling circuit 101 for current sampling of the drive motor 200, and the pre-sampling circuit 101 includes: a first power MOS tube Q1, a second power MOS tube Q2 and a sampling resistor Rc1; wherein the first end of the first power MOS tube Q1 is used to connect to the power supply, and the second end is used to connect to the first end of the second power MOS tube Q2 and the N-phase output end of the drive motor 200 respectively; the second end of the second power MOS tube Q2 is connected to the first input end of the first operational amplifier circuit 102 and one end of the sampling resistor Rc1; the other end of the sampling resistor Rc1 is grounded.

[0093] In one embodiment of the present disclosure, the power MOS tube refers to a metal oxide semiconductor field effect transistor, which is a semiconductor device that works on the principle of field effect. The pre-sampling circuit 101 includes an inverter composed of a first power MOS tube Q1 and a second power MOS tube Q2 connected in series, which can convert the DC power POWER provided by the power supply into AC power, and the sampling resistor Rc1 is arranged at the lower bridge arm of the inverter, that is, the N-phase positive terminal (NLE+). In this way, when the drive motor 200 is running, the lower bridge arm of the inverter is turned on, and current flows through the sampling resistor Rc1, and a corresponding voltage is generated at both ends of the sampling resistor Rc1. At this time, the electrical signal at both ends of the sampling resistor Rc1 can be collected for subsequent calculation of the current sampling value.

[0094] As an optional implementation, the sampling resistor Rc1 is an extremely low resistance high precision alloy resistor.

[0095] In one embodiment of the present disclosure, the alloy resistor is made of alloy material. Due to the strong conductivity of metal, the resistance of the alloy resistor is usually lower than that of ordinary resistors compared with other types of resistors, so it is often used in current sampling. For example, the alloy resistor can be a manganese copper alloy resistor, an iron chromium aluminum alloy resistor, a constantan alloy resistor, a nickel chromium alloy resistor, and a nickel copper alloy resistor. The sampling resistor Rc1 is an extremely low resistance high precision alloy resistor, for example, it can be a manganese copper alloy resistor with a resistance less than 1mΩ, so that the heating problem of the alloy resistor can be reduced when the current in the circuit is large, and it is convenient to control the working temperature in the current sampling circuit 100 to ensure the normal operation of each component.

[0096] Figure 3 FIG. 1 is a connection diagram of a first operational amplifier circuit according to an exemplary embodiment. Figure 3As shown, as an optional implementation, the first operational amplifier circuit 102 includes: a second operational amplifier U2, a first feedback resistor Rf1, a second feedback resistor Rf2, a third feedback resistor Rf3, a fourth feedback resistor Rf4 and a fifth resistor R5; wherein, the inverting input terminal of the second operational amplifier U2 is used to be connected to one end of the first feedback resistor Rf1 and one end of the second feedback resistor Rf2 respectively, the non-inverting input terminal is used to be connected to one end of the third feedback resistor Rf3 and one end of the fourth feedback resistor Rf4 respectively, the output terminal is used to be connected to the other end of the second feedback resistor Rf2 and one end of the fifth resistor R5 respectively, the first power supply terminal is grounded, and the second power supply terminal is connected to the divided voltage; the other end of the first feedback resistor Rf1 is used to be connected to the pre-sampling circuit 101; the other end of the third feedback resistor Rf3 is grounded; the other end of the fourth feedback resistor Rf4 is connected to the reference voltage; the other end of the fifth resistor R5 is used to be connected to the ground line, the second input terminal of the second operational amplifier circuit 103 and the controller 104 respectively.

[0097] In one embodiment of the present disclosure, since the resistance of the sampling resistor Rc1 is usually small, the voltage difference between its two ends is also small, and it is difficult to directly collect the electrical signal accurately, so the electrical signal needs to be amplified by an operational amplifier circuit. In the first operational amplifier circuit 102, the second operational amplifier U2 may be an operational amplifier of model TP2411, which is used to perform a first amplification on the electrical signal of the sampling resistor Rc1; the first feedback resistor Rf1, the second feedback resistor Rf2, the third feedback resistor Rf3 and the fourth feedback resistor Rf4 are used to introduce negative feedback to the second operational amplifier U2 to reduce errors, and at the same time, current limiting protection may also be performed on the first operational amplifier circuit 102, wherein the third feedback resistor Rf3 and the first feedback resistor Rf1 have a symmetrical structure and the same parameters, and the fourth feedback resistor Rf4 and the second feedback resistor Rf2 have a symmetrical structure and the same parameters; the fifth resistor R5 is used to protect the second operational amplifier U2 to prevent the output terminal of the second operational amplifier U2 from being accidentally grounded and causing damage; the reference voltage Vref is also called the reference voltage, which may be 2.5V; the divided voltage VAD is the voltage obtained by dividing the second power supply terminal, which may be 5VAD.

[0098] like Figure 3 As shown, as an optional implementation, the above-mentioned first operational amplifier circuit 102 also includes: a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5; wherein, one end of the second capacitor C2 is used to connect to the other end of the first feedback resistor Rf1, and the other end is used to connect to the other end of the third feedback resistor Rf3; the third capacitor C3 is connected in parallel with the second feedback resistor Rf2; the fourth capacitor C4 is connected in parallel with the fourth feedback resistor Rf4; the fifth capacitor C5 is connected in series with the fifth resistor R5 and is grounded.

[0099] In one embodiment of the present disclosure, the second capacitor C2, the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 can all be capacitors of 470pF, wherein the third capacitor C3 is connected in parallel with the second feedback resistor Rf2, and the fourth capacitor C4 is connected in parallel with the fourth feedback resistor Rf4, for suppressing and filtering the high-frequency noise of the input signal; the second capacitor C2 is located between the first feedback resistor Rf1 and the third feedback resistor Rf3, and can block and isolate the DC components in the pre-sampling circuit 101 and the first operational amplifier circuit 102, avoiding the problems of input voltage drift and signal interference; the fifth capacitor C5 is connected in series with the fifth resistor R5 and grounded, playing a filtering role.

[0100] Figure 4 FIG. 1 is a connection diagram of a second operational amplifier circuit according to an exemplary embodiment. Figure 4 As shown, as an optional implementation, the second operational amplifier circuit 103 includes: a third operational amplifier U3, a fifth feedback resistor Rf5, a sixth feedback resistor Rf6, a seventh feedback resistor Rf7 and a sixth resistor R6; wherein, the inverting input terminal of the third operational amplifier U3 is used to be connected to one end of the fifth feedback resistor Rf5 and one end of the sixth feedback resistor Rf6 respectively, the non-inverting input terminal is used to be connected to one end of the seventh feedback resistor Rf7, the output terminal is used to be connected to the other end of the sixth feedback resistor Rf6 and one end of the sixth resistor R6 respectively, the first power supply terminal is grounded, and the second power supply terminal is connected to the divided voltage; the other end of the fifth feedback resistor Rf5 is used to be connected to the first output terminal of the first operational amplifier circuit 102; the other end of the seventh feedback resistor Rf7 is connected to the reference voltage; the other end of the sixth resistor R6 is used to be connected to the ground line and the controller 104 respectively.

[0101] In one embodiment of the present disclosure, when the drive motor 200 is running at low power and the resistance of the sampling resistor Rc1 is too small, the electrical signal is small and requires a larger amplification factor. However, the operational amplifier performance of the second operational amplifier U2 is difficult to meet the amplification requirements of the electrical signal. Based on this, a second operational amplifier circuit 103 is provided to perform a second amplification on the electrical signal after the first amplification by the first operational amplifier circuit 102, so as to improve the current sampling accuracy of the current sampling circuit 100 under low current conditions.

[0102] In the second operational amplifier circuit 103, the third operational amplifier U3 may be an operational amplifier of model TP2411, which is used to perform a second amplification on the electrical signal of the sampling resistor Rc1 output by the first operational amplifier circuit 102; the fifth feedback resistor Rf5, the sixth feedback resistor Rf6, and the seventh feedback resistor Rf7 are used to introduce negative feedback to the third operational amplifier U3 to reduce errors, and at the same time, current limiting protection can also be performed on the second operational amplifier circuit 103; the sixth resistor R6 is used to protect the third operational amplifier U3 to prevent the output terminal of the third operational amplifier U3 from being accidentally grounded and causing damage; the reference voltage Vref is also called the reference voltage, which can be 2.5V; the divided voltage VAD is the voltage obtained by dividing the second power supply terminal, which can be 5VAD.

[0103] like Figure 4 As shown, as an optional implementation, the second operational amplifier circuit 103 further includes: a sixth capacitor C6 and a seventh capacitor C7; wherein the sixth capacitor C6 is connected in parallel with the sixth feedback resistor Rf6; and the seventh capacitor C7 is connected in series with the sixth resistor R6 and grounded.

[0104] In one embodiment of the present disclosure, the sixth capacitor C6 and the seventh capacitor C7 can be 470pF capacitors, wherein the sixth capacitor C6 and the sixth feedback resistor Rf6 are connected in parallel to suppress and filter the high-frequency noise of the input signal; the seventh capacitor C7 and the sixth resistor R6 are connected in series to ground to play a filtering role.

[0105] As an optional implementation, the first input terminal of the first operational amplifier circuit 102 includes: a first non-inverting input terminal and a first inverting input terminal; wherein the first non-inverting input terminal is connected to a first reference voltage, and the first inverting input terminal is suitable for being connected to the pre-sampling circuit 101; the second input terminal of the second operational amplifier circuit 103 includes: a second non-inverting input terminal and a second inverting input terminal; wherein the second non-inverting input terminal is connected to a second reference voltage, and the second inverting input terminal is connected to the first output terminal of the first operational amplifier circuit 102.

[0106] Figure 5 FIG. 1 is a schematic diagram showing a structure of a current sampling circuit according to an exemplary embodiment. Figure 5 As shown, as an optional implementation, the current sampling circuit 100 further includes: a reference voltage generating circuit 105; the reference voltage generating circuit 105 is used to generate a first reference voltage and / or a second reference voltage.

[0107] In one embodiment of the present disclosure, a reference voltage is generated for each phase current sampling circuit by a reference voltage generating circuit 105 for the first operational amplifier circuit 102 and the second operational amplifier circuit 103, respectively, so as to avoid drift of the reference voltage after the drive motor 200 is started, so as to keep the reference voltage value stable and further improve the accuracy of current sampling.

[0108] Figure 6 FIG. 1 is a connection diagram of a reference voltage generating circuit according to an exemplary embodiment. Figure 6 As shown, the reference voltage generating circuit 105 includes: a first operational amplifier U1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first capacitor C1; wherein one end of the second resistor R2 is connected to the divided voltage, and the other end is used to be connected to one end of the third resistor R3 and the non-inverting input end of the first operational amplifier U1 respectively; the other end of the third resistor R3 is grounded; the first power supply terminal of the first operational amplifier U1 is grounded, the second power supply terminal is connected to the divided voltage, and the inverting input end and the output end are respectively used to be connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is used to be connected to one end of the first capacitor C1 and connected to the first non-inverting input end of the first operational amplifier circuit 102 through the first resistor R1; or, the other end of the fourth resistor R4 is used to be connected to one end of the first capacitor C1 and connected to the second non-inverting input end of the second operational amplifier circuit 103; the first capacitor C1, the other end is grounded.

[0109] In one embodiment of the present disclosure, in the reference voltage generating circuit 105, the first operational amplifier U1 can be an operational amplifier of model TP2411, whose inverting input terminal is directly connected to the output terminal to form a closed loop; the second resistor R2 and the third resistor R3 are voltage-dividing resistors with relatively large resistance values, for example, 10kΩ, which are used to divide the voltage for the first operational amplifier U1; the fourth resistor R4 is used to protect the first operational amplifier U1 to prevent the output terminal of the first operational amplifier U1 from being accidentally grounded and damaged; the first capacitor C1 and the fourth resistor R4 are connected to the ground in series to play a filtering role. In addition, the voltage-dividing voltage VAD is the voltage obtained by dividing the second power supply terminal of the first operational amplifier U1 and the second resistor R2, which can be 5VAD, and correspondingly, the voltage outputted by the output terminal of the first operational amplifier U1 is 2.5V, which is used to provide the reference voltage Vref for the operational amplifier circuit.

[0110] Next, with respect to the controller, the method of converting the electrical signals output by the first operational amplifier circuit and the second operational amplifier circuit to obtain current sampling values ​​and switching the operational amplifier circuits according to the current sampling values ​​is described in detail:

[0111] First, the controller receives the voltage value output by the first operational amplifier circuit and the voltage value output by the second operational amplifier circuit, and samples the two at the center point of the carrier counter at the same time to obtain a current sampling value;

[0112] Then, according to the running state of the driving motor and the magnitude of the current sampling value, the operational amplifier circuit is switched; for example, it may include:

[0113] If the drive motor is in the starting state, the current sampling value is compared with the first threshold value; if the current sampling value is less than the first threshold value, the second operational amplifier circuit is used to control the current of the drive motor; if the current sampling value is greater than or equal to the first threshold value, the first operational amplifier circuit is used to control the current of the drive motor;

[0114] If the driving motor is in a normal operating state at the first moment, the current sampling value is first compared with the first threshold value; if the current sampling value is less than the first threshold value, the second operational amplifier circuit is used to control the current of the driving motor; if the current sampling value is greater than or equal to the first threshold value, and at other moments when the driving motor is in a normal operating state, the current sampling value is compared with the second threshold value, wherein the first threshold value is less than the second threshold value, if the current sampling value is less than the second threshold value, the second operational amplifier circuit is used to control the current of the driving motor; if the current sampling value is greater than or equal to the second threshold value, the first operational amplifier circuit is used to control the current of the driving motor.

[0115] In order to prevent the current sampling value from fluctuating easily around the smaller first threshold, the second threshold is added to judge the current sampling value after the drive motor is running stably, avoiding repeated switching between the first operational amplifier circuit and the second operational amplifier circuit, thereby facilitating stable control of the current of the drive motor.

[0116] Specifically, when the first operational amplifier circuit is used to control the current of the driving motor, the current sampling value I1 corresponding to the first operational amplifier circuit is obtained by the following equations (1) and (2):

[0117] β1=Rf2 / Rf1(1)

[0118] I1=(V1-Vref) / β1Rc1(2)

[0119] Among them, β1 is the amplification factor of the first operational amplifier circuit, Rf2 is the resistance value of the second feedback resistor, Rf1 is the resistance value of the first feedback resistor, V1 is the voltage value output by the first operational amplifier circuit, Vref is the reference voltage, which can be 2.5V, and Rc1 is the resistance value of the sampling resistor.

[0120] Furthermore, when the second operational amplifier circuit is used to control the current of the driving motor, the corresponding current sampling value I2 of the second operational amplifier circuit is obtained by the following equations (3)-(5):

[0121] V1=Vref(1+β2)-β2V2(3)

[0122] β2=Rf5 / Rf6(4)

[0123] I2=(V1-Vref) / β1Rc1(5)

[0124] Among them, V2 is the voltage value output by the second operational amplifier circuit, which is usually in the range of 0-5V, β2 is the amplification factor of the second operational amplifier circuit, Rf5 is the resistance value of the fifth feedback resistor, and Rf6 is the resistance value of the sixth feedback resistor.

[0125] In addition, the present disclosure further provides a current sampling system, which includes a current sampling circuit 100, wherein the current sampling circuit 100 is the above-mentioned current sampling circuit provided by the present disclosure.

[0126] In addition, the present disclosure also provides a vehicle, which includes the above-mentioned current sampling system provided by the present disclosure.

[0127] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0128] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0129] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A current sampling circuit, used for current sampling of a pre-sampling circuit (101), characterized in that: include: A first operational amplifier circuit (102), a second operational amplifier circuit (103) and a controller (104); The first input end of the first operational amplifier circuit (102) is suitable for being connected to the pre-sampling circuit (101), and the first output end of the first operational amplifier circuit (102) is respectively connected to the second input end of the second operational amplifier circuit (103) and the controller (104); The second output end of the second operational amplifier circuit (103) is connected to the controller (104); The controller (104) is adapted to determine the sampling current value of the pre-sampling circuit (101) according to the received electrical signals output by the first operational amplifier circuit (102) and the second operational amplifier circuit (103).

2. The current sampling circuit according to claim 1, characterized in that: The first input end of the first operational amplifier circuit (102) comprises: a first in-phase input end and a first inverting input end; wherein the first in-phase input end is connected to a first reference voltage, and the first inverting input end is suitable for being connected to the pre-sampling circuit (101); The second input terminal of the second operational amplifier circuit (103) comprises: a second non-inverting input terminal and a second inverting input terminal; wherein the second non-inverting input terminal is connected to a second reference voltage, and the second inverting input terminal is connected to the first output terminal of the first operational amplifier circuit (102).

3. The current sampling circuit according to claim 2, characterized in that: The current sampling circuit further comprises: a reference voltage generating circuit (105), wherein the reference voltage generating circuit (105) is used to generate the first reference voltage and / or the second reference voltage; The reference voltage generating circuit (105) comprises: A first operational amplifier (U1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4) and a first capacitor (C1); One end of the second resistor (R2) is connected to the divided voltage, and the other end is used to be connected to one end of the third resistor (R3) and the non-inverting input end of the first operational amplifier (U1) respectively; The other end of the third resistor (R3) is grounded; The first operational amplifier (U1) has a first power supply terminal connected to ground, a second power supply terminal connected to a divided voltage, and an inverting input terminal and an output terminal respectively used to be connected to one end of the fourth resistor (R4); The other end of the fourth resistor (R4) is used to be connected to one end of the first capacitor (C1) and connected to the first non-inverting input end of the first operational amplifier circuit (102) through the first resistor (R1); or the other end of the fourth resistor (R4) is used to be connected to one end of the first capacitor (C1) and connected to the second non-inverting input end of the second operational amplifier circuit (103); The other end of the first capacitor (C1) is grounded.

4. The current sampling circuit according to claim 1, characterized in that: The first operational amplifier circuit (102) comprises: A second operational amplifier (U2), a first feedback resistor (Rf1), a second feedback resistor (Rf2), a third feedback resistor (Rf3), a fourth feedback resistor (Rf4) and a fifth resistor (R5); The second operational amplifier (U2) has an inverting input terminal connected to one end of the first feedback resistor (Rf1) and one end of the second feedback resistor (Rf2), a non-inverting input terminal connected to one end of the third feedback resistor (Rf3) and one end of the fourth feedback resistor (Rf4), an output terminal connected to the other end of the second feedback resistor (Rf2) and one end of the fifth resistor (R5), a first power supply terminal connected to ground, and a second power supply terminal connected to a divided voltage; The first feedback resistor (Rf1), the other end of which is used to be connected to the pre-sampling circuit (101); The other end of the third feedback resistor (Rf3) is grounded; The other end of the fourth feedback resistor (Rf4) is connected to the reference voltage; The other end of the fifth resistor (R5) is used to be connected to the ground line, the second input end of the second operational amplifier circuit (103) and the controller (104) respectively.

5. The current sampling circuit according to claim 4, characterized in that: The first operational amplifier circuit (102) further includes: A second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4) and a fifth capacitor (C5); Wherein, one end of the second capacitor (C2) is used to be connected to the other end of the first feedback resistor (Rf1), and the other end is used to be connected to the other end of the third feedback resistor (Rf3); The third capacitor (C3) is connected in parallel with the second feedback resistor (Rf2); The fourth capacitor (C4) is connected in parallel with the fourth feedback resistor (Rf4); The fifth capacitor (C5) is connected in series with the fifth resistor (R5) and is grounded.

6. The current sampling circuit according to claim 1, characterized in that: The second operational amplifier circuit (103) comprises: a third operational amplifier (U3), a fifth feedback resistor (Rf5), a sixth feedback resistor (Rf6), a seventh feedback resistor (Rf7) and a sixth resistor (R6); The third operational amplifier (U3) has an inverting input terminal connected to one end of the fifth feedback resistor (Rf5) and one end of the sixth feedback resistor (Rf6), a non-inverting input terminal connected to one end of the seventh feedback resistor (Rf7), an output terminal connected to the other end of the sixth feedback resistor (Rf6) and one end of the sixth resistor (R6), a first power supply terminal connected to ground, and a second power supply terminal connected to a divided voltage; The fifth feedback resistor (Rf5), the other end of which is used to be connected to the first output end of the first operational amplifier circuit (102); The other end of the seventh feedback resistor (Rf7) is connected to the reference voltage; The other end of the sixth resistor (R6) is used to be connected to the ground wire and the controller (104) respectively.

7. The current sampling circuit according to claim 6, characterized in that: The second operational amplifier circuit (103) further includes: a sixth capacitor (C6) and a seventh capacitor (C7); Wherein, the sixth capacitor (C6) is connected in parallel with the sixth feedback resistor (Rf6); The seventh capacitor (C7) is connected in series with the sixth resistor (R6) and is grounded.

8. The current sampling circuit according to claim 1, characterized in that: The pre-sampling circuit (101) is also included, which is used for current sampling of the driving motor (200), and the pre-sampling circuit (101) comprises: A first power MOS tube (Q1), a second power MOS tube (Q2) and a sampling resistor (Rc1); The first end of the first power MOS tube (Q1) is used to be connected to a power supply, and the second end is used to be connected to the first end of the second power MOS tube (Q2) and the output end of the drive motor (200) respectively; The second end of the second power MOS tube (Q2) is connected to the first input end of the first operational amplifier circuit (102) and one end of the sampling resistor (Rc1); The other end of the sampling resistor (Rc1) is grounded.

9. The current sampling circuit according to claim 8, characterized in that: The sampling resistor (Rc1) is an extremely low resistance and high precision alloy resistor.

10. A current sampling system, characterized in that: include: A current sampling circuit (100), wherein the current sampling circuit (100) is a current sampling circuit according to any one of claims 1-9.

11. A vehicle, characterized in that: Includes the current sampling system as claimed in claim 10.

Images