Motor current sampling circuit and electric vehicle

Abstract

The utility model relates to a motor current sampling circuit and an electric vehicle, the motor current sampling circuit comprises a first sampling circuit, a second sampling circuit and a controller, the first sampling circuit samples the current flowing through a motor and outputs a first sampling signal to the controller, and the second sampling circuit samples the current flowing through the motor and outputs a second sampling signal to the controller. The first sampling circuit is connected with the controller and outputs a second sampling signal to the controller, the controller responds to the input of the first sampling signal and controls the torque of the motor, the controller further responds to the result that the voltage of the second sampling signal is larger than or equal to a preset threshold value and controls the motor to stop running, and the first sampling circuit and the second sampling circuit are different types of sampling circuits. The motor current sampling circuit adopts two different types of sampling circuits to respectively sample the current of the motor, so that the problem of common cause failure of the sampling circuit is avoided, the reliability of motor current sampling is improved, and the safety of an electric vehicle is further improved.

Description

Technical Field

[0001] This utility model relates to the field of current sampling, and in particular to a motor current sampling circuit and an electric vehicle. Background Technology

[0002] Electric vehicles are gradually becoming one of the mainstream modes of transportation. Electric vehicles include motors, and in the motor control process, high-precision sampling of the motor current is required to accurately control the motor torque, thereby enabling the electric vehicle to drive smoothly. However, current motor current sampling circuits are prone to inaccurate sampling or even failure to sample due to common causes, leading to unsafe and unreliable operation of electric vehicles and reduced safety. Utility Model Content

[0003] The present invention aims to provide a motor current sampling circuit and an electric vehicle that can sample motor current more reliably.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, this utility model provides a motor current sampling circuit, including: a first sampling circuit, a second sampling circuit, and a controller;

[0006] The first sampling circuit is electrically connected to the first input terminal of the controller, and the second sampling circuit is electrically connected to the second input terminal of the controller;

[0007] The first sampling circuit is used to sample the current flowing through the motor and output a first sampling signal to the controller; the second sampling circuit is used to sample the current flowing through the motor and output a second sampling signal to the controller.

[0008] The controller is used to control the torque of the motor in response to the input of the first sampled signal. The controller is also used to control the motor to stop running in response to the result that the voltage of the second sampled signal is greater than or equal to a preset voltage threshold.

[0009] The first sampling circuit and the second sampling circuit are sampling circuits of different types.

[0010] In some embodiments, the first sampling circuit includes a first sensor and a first filtering circuit, wherein the first filtering circuit is electrically connected to the first sensor and the first input terminal of the controller, respectively.

[0011] The first sensor is used to sample the current flowing through the motor and generate a first voltage signal. The first filter circuit is used to filter the first voltage signal and generate the first sampled signal.

[0012] In some embodiments, the second sampling circuit includes a second sensor and a second filtering circuit, wherein the second filtering circuit is electrically connected to the second sensor and the second input terminal of the controller, respectively.

[0013] The second sensor is used to sample the current flowing through the motor and generate a second voltage signal. The second filter circuit is used to filter the second voltage signal and generate the second sampled signal.

[0014] In some embodiments, the model of the first sensor is different from that of the second sensor.

[0015] In some embodiments, the first filter circuit and the second filter circuit are filter circuits of different types.

[0016] In some embodiments, the first filter circuit is an active filter circuit, and the second filter circuit is an RC filter circuit.

[0017] In some embodiments, the motor current sampling circuit further includes a circuit board, the circuit board including a first plate surface and a second plate surface disposed opposite to each other along a first direction, the second plate surface being the side of the circuit board facing the three-phase copper busbar of the motor, the first sensor being mounted on the first plate surface, and the second sensor being mounted on the second plate surface.

[0018] In some embodiments, the motor current sampling circuit further includes a magnetic focusing element;

[0019] The magnetic focusing element is disposed on the circuit board, and the magnetic focusing element and the circuit board form a first receiving cavity and a second receiving cavity that are adjacent to each other in the first direction. The first sensor is located in the first receiving cavity, and the second sensor is located in the second receiving cavity.

[0020] In some embodiments, the magnetic focusing component includes a main body portion and two connecting portions connected to each other. Both connecting portions extend through the circuit board and are respectively connected to opposite ends of the main body portion. Along the first direction, the main body portion is located on one side of the second board surface. The minimum distance between the main body portion and the second board surface is d1, and the distance between the end of the connecting portion away from the main body portion and the first board surface is d2, satisfying d1 = d2.

[0021] In a second aspect, embodiments of the present invention provide an electric vehicle, the electric vehicle including a motor and a motor current sampling circuit as described above.

[0022] In various embodiments of this utility model, the motor current sampling circuit includes a first sampling circuit, a second sampling circuit, and a controller. The first sampling circuit is electrically connected to a first input terminal of the controller, and the second sampling circuit is electrically connected to a second input terminal of the controller. The first sampling circuit samples the current flowing through the motor and outputs a first sampling signal to the controller. The second sampling circuit samples the current flowing through the motor and outputs a second sampling signal to the controller. The controller responds to the input of the first sampling signal and controls the torque of the motor. The controller also responds to the result that the voltage of the second sampling signal is greater than or equal to a preset threshold and controls the motor to stop running. The first and second sampling circuits are sampling circuits of different types. Therefore, this motor current sampling circuit uses two different types of sampling circuits to sample the motor current separately, avoiding the problem of common-cause failure in the sampling circuit, improving the reliability of motor current sampling, and thus improving the safety of electric vehicles. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 This is a structural schematic diagram of one type of electric vehicle provided in this utility model embodiment;

[0025] Figure 2 This is a schematic diagram of the structure of one of the motor current sampling circuits provided in this embodiment of the utility model;

[0026] Figure 3 This is a schematic diagram of the structure of one of the motor current sampling circuits provided in this embodiment of the utility model;

[0027] Figure 4 This is a schematic diagram of the structure of one of the motor current sampling circuits provided in this utility model embodiment. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0029] Please see Figure 1 , Figure 1This is a schematic diagram of the structure of an electric vehicle provided by an embodiment of the present utility model. The electric vehicle includes a motor current sampling circuit 10 and a motor 20. The motor current sampling circuit 10 is electrically connected to the motor 20, and the motor current sampling circuit 10 is used to sample the current flowing through the motor 20.

[0030] In the drive motor system of an electric vehicle, the motor controller controls the motor 20 based on signals from the accelerator pedal, brake pedal, and vehicle speed feedback signals. When the motor 20 needs to accelerate in the forward direction, the motor controller converts the direct current into three-phase alternating current of appropriate frequency and amplitude through its internal circuitry. This three-phase alternating current is then transmitted to the windings of the motor 20 through a three-phase copper busbar, causing the motor 20 to generate a positive rotational torque and drive the vehicle forward.

[0031] If torque control malfunctions, the vehicle may experience sudden acceleration or deceleration. For example, when starting or climbing a hill, motor 20 needs to provide sufficient torque to ensure a smooth climb. During regenerative braking, precise torque control of motor 20 is also crucial to prevent loss of vehicle control. Therefore, accurate torque control of motor 20 is essential for the smooth operation of the electric vehicle.

[0032] To improve the torque control accuracy of motor 20, it is necessary to sample the current flowing through motor 20 with high precision, obtain the sampled current, and then process and analyze the sampled current to achieve precise control of motor 20.

[0033] The current motor current sampling circuit 10 generally uses a single sampling circuit. However, if the sampling circuit fails or fails due to a common cause, it will lead to inaccurate sampling or even failure to sample, which will result in the electric vehicle not being able to operate safely and reliably, and the safety will be reduced.

[0034] Based on the above problems, this utility model embodiment provides a motor current sampling circuit, such as... Figure 2 As shown, the motor current sampling circuit 10 includes a first sampling circuit 11, a second sampling circuit 12, and a controller 13. The first sampling circuit 11 is electrically connected to the first input terminal of the controller 13, and the second sampling circuit 12 is electrically connected to the second input terminal of the controller 13. The first sampling circuit 11 and the second sampling circuit 12 are sampling circuits of different types.

[0035] The first sampling circuit 11 samples the current flowing through the motor 20 and outputs a first sampling signal to the controller 13. The first sampling circuit 11 can be any circuit capable of sampling current, such as: a circuit based on a sampling resistor, where a sampling resistor is used to shunt the current; when current flows through the sampling resistor, a voltage is generated across the resistor, and the magnitude of the current is determined by this voltage value; another example is a circuit based on electromagnetic induction, which converts a large primary current into a small secondary current for measurement based on the principle of electromagnetic induction; yet another example is a circuit based on the Hall effect, using a Hall current sensor to measure the current flowing through the motor 20.

[0036] The first sampling circuit 11 outputs a first sampling signal. The controller 13 receives the first sampling signal, processes and analyzes it, and outputs a corresponding control signal based on the first sampling signal to control the torque of the motor 20. For example, the controller 13 determines whether there is a deviation between the voltage value of the first sampling signal and the set value. If there is a deviation, it indicates that the motor 20 has not reached the preset torque. The controller 13 then generates a corresponding control signal to control the current flowing through the motor 20, thereby controlling the torque of the motor 20 so that the torque of the motor 20 reaches the preset torque.

[0037] The second sampling circuit 12 outputs a second sampling signal, which is received by the controller 13. The controller 13 processes and analyzes this second sampling signal, monitoring the torque of the motor 20 based on it. For example, the controller 13 determines whether the voltage value of the second sampling signal is greater than or equal to a preset voltage threshold. If so, it indicates that the torque of the motor 20 exceeds the preset torque, and the controller 13 generates a stop signal to stop the motor 20. Furthermore, the controller 13 records the corresponding fault code, issues an MCUF fault flag message, and enters a safe state to prevent safety issues.

[0038] The first sampling circuit 11 and the second sampling circuit 12 are different sampling circuits. The two sampling circuits are independent of each other and sample the current flowing through the motor 20 separately without affecting each other's sampling results. The controller 13 performs different motor 20 controls based on the two sampling results. When one sampling circuit fails or fails due to a common cause, the other sampling circuit can still sample normally, and the controller 13 can still accurately control the torque of the motor 20, improving the reliability of motor 20 current sampling and motor 20 control.

[0039] Controller 13 may be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), microcontroller, ARM (Acorn RISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components. Furthermore, controller 13 may also be any conventional processor, controller, microcontroller, or state machine. Controller 13 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP, and / or any other such configuration.

[0040] In summary, this motor current sampling circuit uses two different types of sampling circuits to sample the motor current separately, avoiding common-cause failures in the sampling circuit, improving the reliability of motor current sampling, and thus improving the safety of electric vehicles.

[0041] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of a motor current sampling circuit provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the first sampling circuit 11 includes a first sensor 111 and a first filter circuit 112. The first filter circuit 112 is electrically connected to the first sensor 111 and the first input terminal of the controller 13, respectively.

[0042] The first sensor 111 samples the current flowing through the motor 20 and generates a first voltage signal. The first filter circuit 112 filters the first voltage signal and generates a first sampling signal.

[0043] In some embodiments, the first sensor 111 is a Hall sensor, which collects the magnetic field generated by the current of the motor 20 and converts the current signal of the motor 20 into a voltage signal output.

[0044] In some embodiments, the first filter circuit 112 can be any circuit capable of filtering. For example, an RC filter circuit, an LC filter circuit, and an active filter circuit.

[0045] The first filter circuit 112 filters the first voltage signal to remove interference signals and filter ripple signals, thereby improving the accuracy of the first sampled signal.

[0046] In some embodiments, the second sampling circuit 12 includes a second sensor 121 and a second filtering circuit 122, wherein the second filtering circuit 122 is electrically connected to the second sensor 121 and the second input terminal of the controller 13, respectively.

[0047] The second sensor 121 samples the current flowing through the motor 20 and generates a second voltage signal. The second filter circuit 122 filters the second voltage signal and generates a second sampling signal.

[0048] The first input terminal and the second input terminal of the controller 13 are different ADC ports of the controller 13. For example, the first input terminal is ADC1 port, ADC2 port, and ADC3 port of the controller 13, which are used to receive the U-phase voltage signal, the V-phase voltage signal, and the W-phase voltage signal in the first sampled signal, respectively. The second input terminal is ADC4 port, ADC5 port, and ADC6 port of the controller 13, which are used to receive the U-phase voltage signal, the V-phase voltage signal, and the W-phase voltage signal in the second sampled signal, respectively.

[0049] In some embodiments, the second sensor 121 is a Hall sensor, which collects the magnetic field generated by the current of the motor 20 and converts the current signal of the motor 20 into a voltage signal output.

[0050] In some embodiments, the second filter circuit 122 can be any circuit capable of filtering. For example, an RC filter circuit, an LC filter circuit, and an active filter circuit.

[0051] The second filter circuit 122 filters the second voltage signal to remove interference signals and filter ripple signals, thereby improving the accuracy of the second sampled signal.

[0052] In this embodiment, two sensors are used to sample the current of motor 20, avoiding the inability to sample the motor 20 current due to sensor failure and improving the reliability of motor 20 current sampling. Similarly, two filter circuits are used to filter the voltage signal, avoiding the inability to sample the motor 20 current due to filter circuit failure and improving the reliability of motor 20 current sampling.

[0053] If the first sensor 111 and the second sensor 121 are the same type of sensor, then the first filter circuit 112 and the second filter circuit 122 are different types of filter circuits. Alternatively, if the first sensor 111 and the second sensor 121 are different types of sensors, then the first filter circuit 112 and the second filter circuit 122 can be the same type of filter circuit or different types of filter circuits.

[0054] The model of the first sensor 111 is different from that of the second sensor 121, which can improve the reliability of the current sampling of the motor 20. For example, if the first sensor 111 is a Hall sensor with the model number MLX91208 and the second sensor 121 is a Hall sensor with the model number MLX91218, then the first sensor 111 and the second sensor 121 have different sensitivities and will output different voltage signals.

[0055] If the first sensor 111 is model MLX91208 with a sensitivity of 40mV / mT, the second sensor 121 is model MLX91218 with a sensitivity of 30mV / mT, the current of motor 20 generates a magnetic field with a field strength factor of 70uT / A, and the current of motor 20 is 500A, then the voltage of the first voltage signal U1 = 2.5V + 40mV / mT * 70uT / A * 500A = 2.5V + 1.4V = 3.9V, and the voltage of the second voltage signal U2 = 2.5V + 30mV / mT * 70uT / A * 500A = 2.5V + 1.05V = 3.55V.

[0056] The first sensor 111 and the second sensor 121 are of different models and output different voltage signals, which avoids the risk of vehicle loss of control due to common cause failure of the sensors and further improves the reliability of motor 20 current sampling.

[0057] In some embodiments, the first filter circuit 112 and the second filter circuit 122 are different types of filter circuits, which further improves the reliability of the current sampling of the motor 20.

[0058] For example, the first filter circuit 112 is an active filter circuit, and the second filter circuit 122 is an RC filter circuit. Different types of filter circuits filter the voltage signal output by the sensor, avoiding the risk of vehicle loss of control due to common cause failure of the filter circuit, and further improving the reliability of the current sampling of the motor 20.

[0059] Preferably, the first sensor 111 and the second sensor 121 are different types of sensors, and the first filter circuit 112 and the second filter circuit 122 are different types of filter circuits.

[0060] In this embodiment, taking the first sensor 111 as model MLX91208, the second sensor 121 as model MLX91218, the first filter circuit 112 as an active filter circuit, and the second filter circuit 122 as an RC filter circuit as an example, the working process of the motor current sampling circuit 10 is described:

[0061] The first voltage signal output by the first sensor 111 is filtered by an active filter circuit to obtain a first sampling signal, which is received and processed by the controller 13. The first sampling signal can be transmitted to the L1 layer of the controller 13 to participate in the torque control of the motor 20.

[0062] The second voltage signal output by the second sensor 121 is filtered by an RC filter circuit to obtain a second sampling signal, which is received and processed by the controller 13. The second sampling signal can be transmitted to the L2 layer of the controller 13 to participate in the torque monitoring of the motor 20. The controller 13 determines whether the voltage of the second sampling signal exceeds a preset voltage threshold. If it exceeds the voltage threshold, it indicates that the torque of the motor 20 exceeds a preset torque. Therefore, a stop signal is sent to the motor 20 to control it to stop operating and enter a safe state. Furthermore, the corresponding fault code is recorded, and a CPU fault flag message is issued.

[0063] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a motor current sampling circuit provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the motor current sampling circuit 10 also includes a circuit board 14. The circuit board 14 includes a first plate surface and a second plate surface that are disposed opposite to each other along a first direction. The second plate surface is the side of the circuit board 14 facing the three-phase copper busbar 21 of the motor 20. The circuit board 14 is a PCB board, and the first direction is shown as direction n in the figure.

[0064] The three-phase copper busbar 21 is a conductive component used to connect the three-phase power supply and the three-phase winding of the motor 20. The three-phase power supply is transmitted to the three-phase winding of the motor 20 through the three-phase copper busbar 21, so that the motor 20 generates positive rotational torque and drives the electric vehicle forward.

[0065] When sampling the current of motor 20, the first sensor 111 and the second sensor 121 are mounted on different surfaces of the circuit board 14. The first sensor 111 is mounted on the first surface, and the second sensor 121 is mounted on the second surface. The first surface is the top layer of the circuit board 14, and the second surface is the bottom layer of the circuit board 14.

[0066] The first sensor 111 is installed at any position on the first plate, and the second sensor 121 is installed at any position on the second plate. Preferably, the first sensor 111 is installed at the center of the first plate, and the second sensor 121 is installed at the center of the second plate.

[0067] The first sensor 111 and the second sensor 121 respectively collect the magnetic field generated by the current on the three-phase copper busbar 21 to sample the current of the motor 20, and convert the sampled current signal into a voltage signal and output it to the controller 13.

[0068] In some embodiments, please continue reading Figure 4 The motor current sampling circuit 10 also includes a magnetic focusing element 15, which is disposed on the circuit board 14. The magnetic focusing element 15 and the circuit board 14 form a first receiving cavity and a second receiving cavity adjacent to each other in a first direction. The first sensor 111 is located in the first receiving cavity, and the second sensor 121 is located in the second receiving cavity.

[0069] The magnetic focusing element 15 is a device that arbitrarily concentrates the magnetic field generated by the current on the three-phase copper busbar 21. Examples include magnetic cores, magnetic rings, or magnetic shielding covers. In this embodiment of the invention, a magnetic core is used as the magnetic focusing element 15, and the magnetic core is made of stacked silicon steel sheets.

[0070] This embodiment of the invention uses a magnetic focusing component 15 to uniformly concentrate the magnetic field generated by the current on the three-phase copper busbar 21, while simultaneously shielding it from external magnetic field interference, thus improving system stability. Furthermore, the uniform magnetic field ensures that even if the first sensor 111 and the second sensor 121 are located in different positions, they will acquire the same magnetic field strength, reducing acquisition errors caused by different installation positions and improving sampling accuracy.

[0071] In some embodiments, please continue reading Figure 4 The magnetic focusing component 15 includes a main body 151 and two connecting parts 152 connected to each other. Both connecting parts 152 penetrate through the circuit board 14 and are respectively connected to the two opposite ends of the main body 151. In the first direction, the main body 151 is located on one side of the second plate surface, the minimum distance between the main body 151 and the second plate surface is d1, and the distance between the end of the connecting part 152 away from the main body 151 and the first plate surface is d2.

[0072] In some embodiments, d1 = d2, meaning the circuit board 14 is located at the center of the magnetic focusing element 15. In other embodiments, d1 > d2, or d1 <d2。

[0073] In summary, this motor current sampling circuit uses two sampling circuits to sample the motor current separately, avoiding common-cause failures in the sampling circuit, improving the reliability of motor current sampling, and thus improving the safety of electric vehicles.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above, which are not provided in detail for the sake of brevity; although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A motor current sampling circuit, characterized in that, include: The system comprises a first sampling circuit, a second sampling circuit, and a controller. The first sampling circuit is electrically connected to the first input terminal of the controller, and the second sampling circuit is electrically connected to the second input terminal of the controller; The first sampling circuit is used to sample the current flowing through the motor and output a first sampling signal to the controller; the second sampling circuit is used to sample the current flowing through the motor and output a second sampling signal to the controller. The controller is used to control the torque of the motor in response to the input of the first sampled signal. The controller is also used to control the motor to stop running in response to the result that the voltage of the second sampled signal is greater than or equal to a preset voltage threshold. The first sampling circuit and the second sampling circuit are sampling circuits of different types.

2. The motor current sampling circuit according to claim 1, characterized in that, The first sampling circuit includes a first sensor and a first filtering circuit, wherein the first filtering circuit is electrically connected to the first sensor and the first input terminal of the controller, respectively. The first sensor is used to sample the current flowing through the motor and generate a first voltage signal. The first filter circuit is used to filter the first voltage signal and generate the first sampled signal.

3. The motor current sampling circuit according to claim 2, characterized in that, The second sampling circuit includes a second sensor and a second filtering circuit, wherein the second filtering circuit is electrically connected to the second sensor and the second input terminal of the controller, respectively. The second sensor is used to sample the current flowing through the motor and generate a second voltage signal. The second filter circuit is used to filter the second voltage signal and generate the second sampled signal.

4. The motor current sampling circuit according to claim 3, characterized in that, The model number of the first sensor is different from that of the second sensor.

5. The motor current sampling circuit according to claim 3 or 4, characterized in that, The first filter circuit and the second filter circuit are different types of filter circuits.

6. The motor current sampling circuit according to claim 5, characterized in that, The first filter circuit is an active filter circuit, and the second filter circuit is an RC filter circuit.

7. The motor current sampling circuit according to claim 3, characterized in that, The motor current sampling circuit further includes a circuit board, which includes a first plate surface and a second plate surface disposed opposite to each other along a first direction. The second plate surface is the side of the circuit board facing the three-phase copper busbar of the motor. The first sensor is mounted on the first plate surface, and the second sensor is mounted on the second plate surface.

8. The motor current sampling circuit according to claim 7, characterized in that, The motor current sampling circuit also includes a magnetic focusing component; The magnetic focusing element is disposed on the circuit board, and the magnetic focusing element and the circuit board form a first receiving cavity and a second receiving cavity that are adjacent to each other in the first direction. The first sensor is located in the first receiving cavity, and the second sensor is located in the second receiving cavity.

9. The motor current sampling circuit according to claim 8, characterized in that, The magnetic focusing component includes a main body and two connecting parts connected to each other. Both connecting parts penetrate the circuit board and are respectively connected to opposite ends of the main body. Along the first direction, the main body is located on one side of the second board surface. The minimum distance between the main body and the second board surface is d1. The distance between the end of the connecting part away from the main body and the first board surface is d2, satisfying d1 = d2.

10. An electric vehicle, characterized in that, The electric vehicle includes a motor and a motor current sampling circuit as described in any one of claims 1-9.

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