Current sampling circuit for on-board power supply debugging

Abstract

The utility model provides a kind of current sampling circuit for vehicle-mounted power supply debugging, comprising: microcontroller, with analog-digital conversion port;Operational amplifier, the output of the operational amplifier is connected with the analog-digital conversion port of the microcontroller;And single resistance value is milliohm level sampling resistance network, the sampling resistance network is connected in series to the circuit loop to be sampled, two ends of the sampling resistance network are used as voltage sampling point, the input of the operational amplifier is connected with the sampling resistance network to amplify voltage difference of two ends of the sampling resistance network by differential input mode, and then the current value of the input current is obtained by measuring voltage difference of two ends of the sampling resistance network.It is suitable for direct current or alternating current sampling, and appropriate resistance value can be selected according to actual demand, or series / parallel connection mode is used, to meet the needs of various occasions, without providing separate power supply and peripheral auxiliary resistance, with the advantages of simple structure, low cost and wide versatility.

Description

Technical Field

[0001] This utility model relates to the field of vehicle power supply debugging technology, specifically to a current sampling circuit for vehicle power supply debugging. Background Technology

[0002] With the development of new energy vehicles, the reliability and safety of on-board power supplies, as their core components, are becoming increasingly important.

[0003] Currently, one common current sampling scheme is to use Hall effect sensors for current detection. For example, in a typical Hall current sampling circuit, the input current is sensed by a Hall element, then amplified by an operational amplifier, and finally transmitted to the analog-to-digital converter (ADC) port of a microcontroller (MCU) for processing. However, this scheme has the following drawbacks: First, such as Figure 1 As shown, the circuit structure is complex and requires an additional power supply circuit and external matching circuit.

[0004] Secondly, since MCUs cannot directly process current signals, they need to be converted into voltage signals, and this conversion process is non-linear, such as... Figure 2 As shown, this makes software algorithm processing difficult, especially when used as a reference for current loop control in power circuits, making it hard to guarantee control accuracy.

[0005] To overcome the above problems, the following improvements have emerged in the prior art: Chinese utility model patent CN215526051U discloses a battery pack sampling circuit that connects a sampling resistor in series in the power supply circuit of the analog front end and obtains the current signal by detecting the voltage difference across the resistor. Although this solution simplifies some aspects of the structure, it still requires an analog front end, a controller, and possible temperature compensation circuitry, resulting in high system complexity and cost. Furthermore, it is specifically designed for BMS systems and is not suitable for general-purpose vehicle power supply debugging scenarios.

[0006] Chinese invention patent CN117978027A discloses a method, verification method, device, medium, and motor closed-loop control system for estimating bus current in a motor drive circuit. The method estimates the current indirectly by calculating the total three-phase power and bus voltage. Although it can save some hardware, its estimation accuracy is affected by various factors such as motor wiring method, MOSFET switching process, dead time, and MCU loss. The algorithm is complex and has limited applicability, making it difficult to promote its use in the high-precision and high-reliability vehicle power supply debugging environment.

[0007] It is evident that existing current sampling schemes still have significant shortcomings in terms of circuit complexity, cost control, and versatility. There is an urgent need for a current sampling scheme that is simple in structure, low in cost, and applicable to various debugging scenarios. Utility Model Content

[0008] The technical problem to be solved by this utility model is how to provide a current sampling scheme with a simple structure that is applicable to various vehicle power supply debugging scenarios.

[0009] To solve the above-mentioned technical problems, this utility model provides a current sampling circuit for vehicle power supply debugging, comprising: Microcontroller with analog-to-digital conversion port; An operational amplifier, the output of which is connected to the analog-to-digital converter port of the microcontroller; and A sampling resistor network with a single resistance value in the milliohm range is connected in series in the circuit loop to be sampled. The two ends of the sampling resistor network serve as voltage sampling points. The input terminal of the operational amplifier is connected to the sampling resistor network to amplify the voltage difference across the sampling resistor network through differential input. The input current value is obtained by measuring the voltage difference across the sampling resistor network.

[0010] Furthermore, the sampling resistor network consists of multiple milliohm-level metal film resistors.

[0011] Furthermore, the sampling resistor network is composed of multiple metal film resistors connected in series and / or in parallel.

[0012] Preferably, the resistance value of the metal film resistor is in the range of 0.1-5mΩ.

[0013] Preferably, the operational amplifier is model NSI1300D25-Q1SWVR.

[0014] Preferably, the microcontroller is model F280049CPZQR.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention replaces the existing Hall sensor with a milliohm-level sampling resistor, enabling the direct output of a voltage signal that is linearly related to the current. It is suitable for DC or AC sampling, and the appropriate resistance value can be selected according to actual needs, or a series / parallel connection method can be used to meet the needs of various occasions. It does not require a separate power supply or external auxiliary resistor, and has the advantages of simple structure, low cost and wide versatility. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a typical Hall current sampling circuit in the existing technology; Figure 2 The diagram shows the Hall current sampling VI curve in the existing technology; Figure 3 This is a schematic diagram of the current sampling circuit disclosed in an embodiment of the present utility model.

[0017] In the diagram: 10, sampling resistor network; 20, operational amplifier; 30, microcontroller. Detailed Implementation

[0018] To make the technical solutions and effects of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0019] The present invention aims to provide a current sampling circuit for vehicle power supply debugging, which solves the drawbacks of existing technologies such as complex structure, poor versatility and high cost.

[0020] Please see Figure 3 The on-board power supply debugging current sampling circuit mainly includes a sampling resistor network 10, an operational amplifier 20, and a microcontroller 30.

[0021] The microcontroller 30 has an analog-to-digital converter port for converting the analog voltage signal output from the operational amplifier 20, which is proportional to the current, into a digital quantity in real time for processing by the internal program. Preferably, the microcontroller 30 is model F280049CPZQR.

[0022] The output of operational amplifier 20 is connected to the analog-to-digital converter port of microcontroller 30. Preferably, operational amplifier 20 is an NSI1300D25-Q1SWVR.

[0023] In this scheme, the sampling resistor network 10 is the core sensing component of the circuit, which directly determines the accuracy, linearity, and range of current sampling. It is connected in series in the main current circuit of the vehicle power supply under test. Due to its extremely small resistance, the voltage drop across it is also very small, thereby minimizing the power loss and voltage impact of the sampling circuit itself on the main circuit and ensuring the accuracy of the measurement.

[0024] A sampling resistor network 10 is connected in series to the circuit loop to be sampled. The two ends of the sampling resistor network 10 serve as voltage sampling points. The input terminal of the operational amplifier 20 is connected to the sampling resistor network 10 to amplify the voltage difference across the sampling resistor network 10 through differential input. The input current value is then obtained by measuring the voltage difference across the sampling resistor network 10. Since the voltage difference ΔV=I*R generated by the sampling resistor network 10 has a strictly linear relationship with the current I, it fundamentally solves the technical problem of nonlinear conversion of VI in traditional Hall sensors. This simplifies the software workload and improves sampling accuracy. When used as a reference value for subsequent current loop design, it can effectively improve control precision.

[0025] Specifically, the sampling resistor network 10 is composed of multiple milliohm-level metal film resistors connected in series and / or parallel. Preferably, the resistance value of each individual resistor in the sampling resistor network 10 is in the milliohm range. The resistance value of the metal film resistors ranges from 0.1 to 5 mΩ.

[0026] Because there are many types of metal film resistors, the appropriate resistance value can be selected according to the actual debugging requirements, or a series / parallel connection method can be used to meet the needs of various occasions. At the same time, this circuit does not require a separate power supply and external auxiliary resistors like Hall current sensors, and has the advantages of simple structure and low cost.

[0027] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A current sampling circuit for vehicle power supply debugging, characterized in that, include: The microcontroller (30) has an analog-to-digital conversion port; An operational amplifier (20), the output of which is connected to the analog-to-digital converter port of the microcontroller (30); and A sampling resistor network (10) with a single resistance value in the milliohm range is connected in series to the circuit loop to be sampled. The two ends of the sampling resistor network (10) serve as voltage sampling points. The input terminal of the operational amplifier (20) is connected to the sampling resistor network (10) to amplify the voltage difference across the sampling resistor network (10) through differential input. The current value of the input current is obtained by measuring the voltage difference across the sampling resistor network (10).

2. The current sampling circuit for vehicle power supply debugging according to claim 1, characterized in that, The sampling resistor network (10) consists of multiple milliohm-level metal film resistors.

3. The current sampling circuit for vehicle power supply debugging according to claim 2, characterized in that, The sampling resistor network (10) is composed of multiple metal film resistors connected in series and / or in parallel.

4. The current sampling circuit for vehicle power supply debugging according to claim 2, characterized in that, The resistance value of the metal film resistor is in the range of 0.1-5mΩ.

5. The current sampling circuit for vehicle power supply debugging according to claim 1, characterized in that, The operational amplifier (20) is model NSI1300D25-Q1SWVR.

6. The current sampling circuit for vehicle power supply debugging according to claim 1, characterized in that, The microcontroller (30) is model F280049CPZQR.

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