Motor current sampling circuit based on operational amplifier, electronic controller and new energy automobile

Abstract

The utility model provides a motor current sampling circuit based on an operational amplifier, an electronic controller and a new energy automobile, and relates to the technical field of electronic circuits, and the motor current sampling circuit comprises a sampling resistor which is connected in series in a power supply loop of a motor and is used for converting a current signal of the motor into a voltage signal; the first operational amplifier circuit is used for amplifying the voltage signal to obtain an amplified voltage signal; and the filter circuit is used for filtering the amplified voltage signal to obtain a ripple signal, and sending the ripple signal to the second operational amplifier circuit for amplification to obtain an amplified ripple signal for the single-chip microcomputer to identify. The beneficial effects are that the motor current is subjected to direct current and alternating current separation and filtering processing through the hardware circuit, and then is amplified through the second operational amplifier circuit, so that the single-chip microcomputer can easily identify current ripples under the condition of weak performance, the performance requirement on the single-chip microcomputer is greatly reduced, and the motor current can be well, stably and reliably identified; and the product competitiveness is greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field especially relates to a motor current sampling circuit based on operational amplifier, electronic controller and new energy automobile. BACKGROUND

[0002] In recent years, the global environmental protection consciousness and the urgent demand for energy structure transformation promote the rapid development of new energy automobile industry. Electric vehicles with its zero emission, low noise, high energy efficiency and other advantages, quickly occupied a place in the automobile market, and the market share continues to expand. With the continuous progress of electric vehicle technology, the trend of in-vehicle intelligence and electronic is increasingly significant, which not only reflects in the driving assistance system, information entertainment system and other aspects, but also goes deeper into the control and management of vehicle power system.

[0003] The power system of electric vehicle is composed of battery pack, motor and its controller, among which the motor controller plays a crucial role as a bridge connecting the battery and the motor. With the increasing performance requirements of electric vehicles, the number of electronic components inside the motor controller increases significantly, and the motor load becomes more complex and variable. In order to ensure the efficient and stable operation of the motor, accurate monitoring of motor current has become a key task. Traditionally, the method of detecting motor current is to connect a precision resistor in series in the circuit, and use Ohm's law to convert the current into a voltage signal, and then process it through an amplification circuit to make the voltage signal reach the range that can be recognized by the single-chip microcomputer (MCU).

[0004] However, with the increasing demand for power system control accuracy of electric vehicles, this traditional current detection method faces many challenges. First, the dynamic range of motor current in modern electric vehicles is large, and contains rich harmonic components, i.e. current ripple, which has a direct impact on the efficiency, noise and life of the motor. In order to accurately capture and process these high-frequency current ripples, the single-chip microcomputer needs to sample the voltage signal at high frequency, which requires the single-chip microcomputer to have a high main frequency and a high-precision analog-to-digital converter (ADC). High-frequency sampling not only increases the processing burden of the single-chip microcomputer, but also puts higher requirements on hardware resources, thus increasing the overall system cost.

[0005] In addition, the traditional detection method limits the amplification of the ripple current while synchronously amplifying the direct current component of the motor current. This is because the design of the amplification circuit needs to maximize the gain of the ripple signal while ensuring the accuracy of the direct current component. However, in actual operation, there is often a contradiction between the two, especially when using low-performance single-chip microcomputers, due to limited processing capacity, it is difficult to effectively identify and process small current ripples while ensuring the accuracy of the direct current component, which directly affects the control accuracy and efficiency of the motor. UTILITY MODEL CONTENT

[0006] In view of the problems in the prior art, the utility model provides a motor current sampling circuit based on operational amplifier, including:

[0007] Sampling resistance, series connection in the power supply circuit of motor, for converting the current signal of motor into voltage signal;

[0008] First operational amplifier circuit, the sampling point of sampling resistance is connected, for amplifying the voltage signal to obtain the amplified voltage signal;

[0009] Filter circuit, respectively connecting the first operational amplifier circuit and second operational amplifier circuit, for filtering the amplified voltage signal to obtain ripple signal, and sending the ripple signal to the second operational amplifier circuit to obtain the amplified ripple signal for the recognition of single-chip microcomputer.

[0010] Preferably, the filter circuit is a high-pass filter.

[0011] Preferably, the high-pass filter includes a first capacitor, one end of the first capacitor is connected to the output end of the first operational amplifier circuit, and the other end is connected to the ground through a first resistor.

[0012] Preferably, the second operational amplifier circuit includes:

[0013] Operational amplifier, one end of the second resistor is connected to the non-inverting input terminal of the operational amplifier, the other end of the second resistor is connected to the output terminal of the filter circuit, the non-inverting input terminal is also connected to the ground through a second capacitor, the inverting input terminal is respectively connected to one end of a third resistor and one end of a fourth resistor, the other end of the third resistor is connected to the ground, and the other end of the fourth resistor is connected to the output terminal of the operational amplifier;

[0014] Fifth resistor, one end of the fifth resistor is respectively connected to one end of a sixth resistor and one end of a seventh resistor, the other end of the fifth resistor is connected to the non-inverting input terminal, the other end of the sixth resistor is connected to the power supply, and the other end of the seventh resistor is connected to the ground.

[0015] Preferably, a third capacitor is connected between the non-inverting input terminal and the inverting input terminal.

[0016] Preferably, it further includes a fourth capacitor, one end of the fourth capacitor is connected to the inverting input terminal, and the other end is connected to the ground; and / or a fifth capacitor is connected across the fourth resistor.

[0017] Preferably, it further includes an eighth resistor, one end of the eighth resistor is connected to the output terminal of the operational amplifier, the other end of the eighth resistor is respectively connected to one end of a sixth capacitor and a sampling pin of the single-chip microcomputer, and the other end of the sixth capacitor is connected to the ground.

[0018] Preferably, the first operational amplifier circuit is integrated in a pre-drive chip of the motor.

[0019] The utility model also provides an electronic controller, the inside integrated singlechip of electronic controller, the singlechip is connected motor through above -mentioned motor current sampling circuit to obtain the ripple signal after amplification, and then the ripple current of motor is identified.

[0020] The utility model also provides a new energy automobile, including above -mentioned electronic controller.

[0021] The above technical scheme has the following advantages or beneficial effects: the motor current is separated and filtered by the hardware circuit into direct current and alternating current, and then amplified by the second operational amplifier circuit, so that the single-chip microcomputer can easily identify the current ripple even if its performance is weak, greatly reducing the performance requirements of the single-chip microcomputer and enabling the motor current to be stably and reliably identified, and greatly improving the product competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 For the preferred embodiment of the utility model, a schematic diagram of the overall structure of the motor current sampling circuit based on the operational amplifier is shown in the figure.

[0023] Figure 2 For the preferred embodiment of the utility model, a circuit diagram of the filter circuit and the second operational amplifier circuit is shown in the figure.

[0024] Figure 3 For the preferred embodiment of the utility model, a schematic diagram of the ripple signal after amplification is shown in the figure. DETAILED DESCRIPTION

[0025] The utility model will be described in detail below in combination with the drawings and specific embodiments. The utility model is not limited to this embodiment, as long as it conforms to the spirit of the utility model, other embodiments can also belong to the scope of the utility model.

[0026] In the preferred embodiment of the utility model, based on the above problems existing in the prior art, a motor current sampling circuit based on the operational amplifier is provided, as shown in the figure, which comprises: Figure 1

[0027] A sampling resistor R is connected in series in the power supply circuit of the motor M, for converting the current signal of the motor M into a voltage signal;

[0028] A first operational amplifier circuit 100 is connected to the sampling point of the sampling resistor R, for amplifying the voltage signal to obtain an amplified voltage signal;

[0029] ​The filter circuit 200 is connected with the first operational amplifier circuit 100 and the second operational amplifier circuit 300 respectively, and is used for filtering the amplified voltage signal to obtain a ripple signal, and sending the ripple signal to the second operational amplifier circuit 300 to obtain an amplified ripple signal for identification by the single-chip microcomputer MCU.

[0030] Specifically, in the embodiment, the power supply circuit comprises a first NMOS tube N1, a second NMOS tube N2, a third NMOS tube N3 and a fourth NMOS tube N4, wherein the gates of the first NMOS tube N1, the second NMOS tube N2, the third NMOS tube N3 and the fourth NMOS tube N4 are connected to the pre-driver chip 400 of the motor M, the drain of the first NMOS tube N1 is connected to the drain of the third NMOS tube N3, the source of the second NMOS tube N2 is connected to the source of the fourth NMOS tube N3, the source of the first NMOS tube N1 is connected to the drain of the second NMOS tube N2 and one end of the motor M respectively, and the source of the third NMOS tube N3 is connected to the drain of the fourth NMOS tube N4 and the other end of the motor M respectively. The source of the second NMOS tube N2 and the source of the fourth NMOS tube N3 are also connected to one end of a sampling resistor R, the other end of the sampling resistor R is grounded, and the non-grounded end of the sampling resistor R is connected to the input end of the first operational amplifier circuit 100 as a sampling point.

[0031] Further specifically, the first operational amplifier circuit 100 is preferably integrated in the pre-driver chip 400 of the motor M, and the model of the pre-driver chip 400 is DR7804Q, and the pre-driver chip 400 can be configured with a suitable amplification multiple, such as 10 times amplification, by software.

[0032] In the preferred embodiment of the utility model, the filter circuit 200 is a high-pass filter.

[0033] In the preferred embodiment of the utility model, the high-pass filter comprises a first capacitor C1, one end of the first capacitor C1 is connected to the output end of the first operational amplifier circuit 100, and the other end is grounded through a first resistor R1.

[0034] Specifically, in the embodiment, the amplified voltage signal obtained by the first operational amplifier circuit 100 is filtered by the high-pass filter formed by the first capacitor C1 and the first resistor R1, and the high-pass filter has a corresponding cut-off frequency, such as 141.8493HZ, and the ripple higher than the cut-off frequency in the amplified voltage signal can pass through, and the corresponding direct current component is filtered out.

[0035] The amplified ripple signal obtained by the second operational amplifier circuit 300 again is input into the single-chip microcomputer MCU for further processing. The second operational amplifier circuit 300 can provide a suitable amplification multiple, such as 10 times amplification, by reasonably configuring the parameters of each component in the second operational amplifier circuit 300.

[0036] In the preferred embodiment of the utility model, the second operational amplifier circuit 300 comprises:

[0037] The operational amplifier 301, one end of the second resistor R2 is connected to the noninverting input end of the operational amplifier 301, the other end of the second resistor R2 is connected to the output end of the filter circuit, the noninverting input end is also grounded through the second capacitor C2, the inverting input end is connected to one end of the third resistor R3 and one end of the fourth resistor R4 respectively, the other end of the third resistor R3 is grounded, and the other end of the fourth resistor R4 is connected to the output end of the operational amplifier 301.

[0038] The fifth resistor R5, one end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and one end of the seventh resistor R7 respectively, the other end of the fifth resistor R5 is connected to the noninverting input end, the other end of the sixth resistor R6 is connected to the power supply VCC, and the other end of the seventh resistor R7 is grounded.

[0039] Specifically, in the embodiment, the model of the operational amplifier 301 is LM2904, the positive power supply pin of the operational amplifier 301 is connected to the power supply VCC and one end of the seventh capacitor C7 respectively, and the other end of the seventh capacitor C7 is grounded. By arranging the seventh capacitor C7, the power supply noise can be effectively filtered out, the operational amplifier 301 has a clean and stable power supply, and therefore the stability of the overall circuit is improved.

[0040] In the preferred embodiment of the utility model, the third capacitor C3 is connected between the noninverting input end and the inverting input end.

[0041] In the preferred embodiment of the utility model, the fourth capacitor C4, one end of the fourth capacitor C4 is connected to the inverting input end, the other end is grounded, and / or the fifth capacitor C5 is connected to both ends of the fourth resistor R4.

[0042] In the preferred embodiment of the utility model, the eighth resistor R8, one end of the eighth resistor R8 is connected to the output end of the operational amplifier 301, the other end is connected to one end of the sixth capacitor C6 and the sampling pin of the single-chip microcomputer MCU respectively, and the other end of the sixth capacitor C6 is grounded.

[0043] As shown in the figure, Figure 3 In the case that the amplification multiples of the first operational amplifier circuit 100 and the second operational amplifier circuit 300 are both 10 times, the peak-to-peak value of the amplified ripple signal can reach 1.5V, and even the single-chip microcomputer MCU with poor performance can easily identify the motor current ripple period.

[0044] The utility model also provides an electronic controller, the single-chip microcomputer is integrated in the electronic controller, the single-chip microcomputer is connected to the motor through the above-mentioned motor current sampling circuit to obtain the amplified ripple signal, and then identifies the ripple current of the motor.

[0045] The utility model also provides a new energy automobile, including above -mentioned electronic controller.

[0046] The above description is only the preferred embodiment of the utility model, and does not limit the implementation and protection scope of the utility model, and for those skilled in the art, it should be realized that the scheme obtained by equivalent replacement and obvious change of the present application and drawings should be included in the protection scope of the utility model.

Claims

1. An operational amplifier based motor current sampling circuit, comprising: The motor current sampling circuit comprises: a sampling resistor connected in series in a power supply circuit of a motor for converting a current signal of the motor into a voltage signal; a first operational amplifier circuit connected to a sampling point of the sampling resistor for amplifying the voltage signal to obtain an amplified voltage signal; a filter circuit connected to the first operational amplifier circuit and a second operational amplifier circuit respectively for filtering the amplified voltage signal to obtain a ripple signal and sending the ripple signal to the second operational amplifier circuit for amplification to obtain an amplified ripple signal for identification by a single-chip microcomputer.

2. The motor current sampling circuit of claim 1, wherein, The filter circuit is a high-pass filter.

3. The motor current sampling circuit of claim 2, wherein, The high-pass filter comprises a first capacitor, one end of the first capacitor being connected to an output end of the first operational amplifier circuit and the other end being connected to ground through a first resistor.

4. The motor current sampling circuit of claim 1, wherein, The second operational amplifier circuit comprises: an operational amplifier, a same-phase input end of the operational amplifier being connected to one end of a second resistor, the other end of the second resistor being connected to an output end of the filter circuit, the same-phase input end being further connected to ground through a second capacitor, an opposite-phase input end being connected to one end of a third resistor and one end of a fourth resistor respectively, the other end of the third resistor being connected to ground, the other end of the fourth resistor being connected to an output end of the operational amplifier; a fifth resistor, one end of the fifth resistor being connected to one end of a sixth resistor and one end of a seventh resistor respectively, the other end of the fifth resistor being connected to the same-phase input end, the other end of the sixth resistor being connected to a power supply, the other end of the seventh resistor being connected to ground.

5. The motor current sampling circuit of claim 4, wherein, A third capacitor is connected between the same-phase input end and the opposite-phase input end.

6. The motor current sampling circuit of claim 4, wherein, The motor current sampling circuit further comprises a fourth capacitor, one end of the fourth capacitor being connected to the opposite-phase input end and the other end being connected to ground, and / or a fifth capacitor connected across the fourth resistor.

7. The motor current sampling circuit of claim 4, wherein, The motor current sampling circuit further comprises an eighth resistor, one end of the eighth resistor being connected to the output end of the operational amplifier, the other end of the eighth resistor being connected to one end of a sixth capacitor and a sampling pin of the single-chip microcomputer respectively, the other end of the sixth capacitor being connected to ground.

8. The motor current sampling circuit of claim 1, wherein, The first operational amplifier circuit is integrated in a pre-driver chip of the motor.

9. An electronic controller characterized by, The electronic controller internally integrated with a single-chip microcomputer is connected to the motor through the motor current sampling circuit to obtain the amplified ripple signal and further identify a ripple current of the motor.

10. A new energy vehicle, characterized in that, The electronic controller of claim 9 is provided.

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