Resistor for constant current source control circuit and constant current source control circuit

Abstract

The utility model relates to a constant current source control circuit, in particular to a resistor for a constant current source control circuit and the constant current source control circuit, which comprise a manganese copper wire and a metal film resistor which are connected in parallel, and has the beneficial effects that a novel sampling resistor structure formed by connecting the manganese copper wire and the metal film resistor in parallel is introduced into the constant current source control circuit; the problems of large temperature excursion and low precision of a traditional resistor are obviously improved, so that constant current output is kept in different temperature environments, and the test stability and accuracy are improved. According to the structure, the excellent temperature stability of the manganese copper wire is combined with the high-resistance characteristic of the metal film resistor, so that the power bearing capacity of the constant current source is improved, and the constant current precision is ensured. In the aspect of circuit control, a plurality of current gears are flexibly switched through combination of a first control signal and a second control signal, meanwhile, multi-stage voltage output selection is achieved in cooperation with an analog switch, and the optimal gear can be automatically matched according to a measured resistance value.

Description

Technical Field

[0001] This utility model relates to the field of constant current source control circuit technology, and in particular to a resistor and constant current source control circuit for use in a constant current source control circuit. Background Technology

[0002] In motor testing, the DC resistance test of the motor stator winding is a crucial comprehensive test item. This test is mainly used to evaluate the electrical performance of the motor stator winding to determine whether it meets design requirements. Traditional testing methods typically rely on dedicated DC resistance meters to obtain resistance values ​​through precise current control and voltage measurement. Among these methods, the four-wire method is the most common and accurate. The core technologies of the four-wire method include constant current source design and sampling resistor test range control. The constant current source provides a stable current, while the sampling resistor is used to detect the voltage drop after the current passes through the motor stator winding, further calculating the resistance value.

[0003] However, existing technologies have certain limitations in practical applications, especially when using ordinary resistors as constant current source sampling resistors. Because ordinary resistors exhibit significant temperature drift under varying ambient temperatures, their resistance values ​​change significantly with temperature variations. This temperature-induced resistance change directly affects the accuracy of the test results, leading to substantial testing errors under different operating environments and failing to meet the accuracy requirements for DC resistance testing of motor stator windings in industrial environments. Therefore, a new technical solution is urgently needed to improve the stability and accuracy of DC resistance testing of motor stator windings, particularly in industrial environments with significant temperature variations. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology and provide a resistor and constant current source control circuit for a constant current source control circuit.

[0005] This utility model is achieved through the following technical solution:

[0006] A resistor for a constant current source control circuit, the resistor comprising a manganese copper wire and a metal film resistor connected in parallel.

[0007] Preferably, the manganese copper wire has a diameter of 3.5 mm, a length of 41 cm, and a resistance of 2 Ω.

[0008] Preferably, the resistance of the metal film resistor is 1MΩ.

[0009] A constant current source control circuit includes the resistor described above.

[0010] Preferably, the constant current source control circuit includes an operational amplifier, a voltage control module, a first resistor, a second resistor, a third resistor, a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch;

[0011] The positive terminal of the operational amplifier is connected to the voltage control module, and the voltage control module can control the voltage input to the positive terminal of the operational amplifier.

[0012] The first end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is grounded.

[0013] The gate of the first semiconductor switch is connected to the first control signal, the drain is connected to the first terminal of the first resistor, and the source is grounded.

[0014] The gate of the second semiconductor switch is connected to the second control signal, the drain is connected between the second resistor and the third resistor, and the source is grounded to the second end of the third resistor;

[0015] The gate of the third semiconductor switch is connected to the signal output terminal of the operational amplifier, and the drain is connected to the constant current source signal.

[0016] The negative terminal of the operational amplifier, the source of the third semiconductor switch, the second terminal of the first resistor, and the second terminal of the second resistor are all connected to the first node;

[0017] The first resistor is the resistor used in the constant current source control circuit described above.

[0018] Preferably, the voltage control module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an analog switch;

[0019] The fourth resistor, the fifth resistor, the sixth resistor, and the seventh resistor are connected in series to form a resistor string, and their two ends are respectively connected to the positive and negative terminals of the input voltage.

[0020] The input terminal of the analog switch can be selectively connected to the connection node between adjacent resistors in the resistor string, and the output terminal is connected to the positive signal input terminal of the operational amplifier.

[0021] Preferably, the input voltage of the resistor string is 2.5V;

[0022] When the input terminal of the analog switch is connected between the fourth resistor and the fifth resistor, the input voltage at the positive terminal of the operational amplifier is 1V.

[0023] When the input terminal of the analog switch is connected between the fifth resistor and the sixth resistor, the input voltage at the positive terminal of the operational amplifier is 0.5V.

[0024] When the input terminal of the analog switch is connected between the sixth resistor and the seventh resistor, the input voltage at the positive terminal of the operational amplifier is 0.1V.

[0025] Preferably, the first semiconductor switch, the second semiconductor switch, and the third semiconductor switch are all N-channel field-effect transistors.

[0026] The beneficial effects of this utility model are:

[0027] By introducing a novel sampling resistor structure consisting of a manganese copper wire and a metal film resistor connected in parallel into the constant current source control circuit, the problems of large temperature drift and low accuracy of traditional resistors are significantly improved. This allows for a constant current output under different temperature environments, enhancing test stability and accuracy. This structure combines the excellent temperature stability of the manganese copper wire with the high resistance characteristics of the metal film resistor, improving both the power carrying capacity of the constant current source and ensuring constant current accuracy. In terms of circuit control, the combination of a first and second control signal enables flexible switching between multiple current levels. Simultaneously, an analog switch allows for multi-level voltage output selection, automatically matching the optimal level based on the measured resistance value. This device achieves linked adjustment of the constant current source current level and output voltage, possessing a high degree of intelligence and self-adaptation, effectively improving the reliability and accuracy of DC resistance testing of motor stator coils in complex industrial environments. Attached Figure Description

[0028] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and preferred embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0030] In the description of the utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model.

[0031] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] This utility model provides a constant current source control circuit for detecting the DC resistance of a motor stator coil. The circuit includes an operational amplifier U1, a voltage control module, a first resistor R1, a second resistor R2, a third resistor R3, a first semiconductor switch Q1, a second semiconductor switch Q2, and a third semiconductor switch Q3.

[0033] The first resistor R1 comprises a manganese copper wire and a metal film resistor connected in parallel. The manganese copper wire has a diameter of 3.5 mm, a length of 41 cm, and a resistance of 2 Ω. The metal film resistor has a resistance of 1 MΩ. This invention improves the stability of current output and measurement accuracy in DC resistance testing by modifying the sampling resistor structure of the constant current source. Specifically, the original 2 Ω resistor is replaced with a 2 Ω sampling resistor made of Ф3.5 mm manganese copper wire, 41 cm in length. This material has extremely low temperature drift characteristics, which can significantly reduce the influence of ambient temperature changes on the resistance value, thereby effectively reducing test errors. Simultaneously, to enhance the power carrying capacity of the constant current source, a 1 MΩ metal film resistor is connected in parallel with the manganese copper wire resistor, forming a parallel structure. Using a common packaging method, heat dissipation capacity and safety are improved without significantly changing the total resistance value. This structure not only possesses excellent temperature drift performance and power adaptability but also facilitates integrated packaging, meeting the high precision, stability, and reliability requirements of industrial environments, and has good engineering application value.

[0034] The voltage control module is connected to the positive input terminal of operational amplifier U1, and it controls the voltage level at the positive input terminal. Specifically, the voltage control module includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an analog switch S1. These resistors are connected in series to form a resistor string, with the two ends connected to the positive and negative terminals of the input voltage, which is 2.5V. The input terminal of analog switch S1 can selectively connect to the connection node between adjacent resistors in the resistor string, and its output terminal is connected to the positive input terminal of operational amplifier U1. Specifically, R4 has a resistance of 3000Ω, R5 has a resistance of 1000Ω, R6 has a resistance of 800Ω, and R7 has a resistance of 200Ω. When the input terminal of analog switch S1 is connected between the fourth resistor R4 and the fifth resistor R5, the positive input voltage of operational amplifier U1 is 1V; when the input terminal of analog switch S1 is connected between the fifth resistor R5 and the sixth resistor R6, the positive input voltage of operational amplifier U1 is 0.5V; when the input terminal of analog switch S1 is connected between the sixth resistor R6 and the seventh resistor R7, the positive input voltage of operational amplifier U1 is 0.1V. The output terminal of analog switch S1 is connected to the positive input terminal of operational amplifier U1.

[0035] The first terminal of the second resistor R2 is connected to the first terminal of the third resistor R3, and the second terminal of the third resistor R3 is grounded. Further, the resistance of R2 is 20Ω, and the resistance of R3 is 2000Ω. The gate of the first semiconductor switch Q1 is connected to the first control signal A1, the drain is connected to the first terminal of the first resistor R1, and the source is grounded. A1 controls the on / off state of the first semiconductor switch Q1. The gate of the second semiconductor switch Q2 is connected to the second control signal A2, the drain is connected between the second resistor R2 and the third resistor R3, and the source is grounded and connected to the second terminal of the third resistor R3. A2 controls the on / off state of the second semiconductor switch Q2. The gate of the third semiconductor switch Q3 is connected to the signal output terminal of the operational amplifier U1, and the drain is connected to a constant current source signal; the negative input terminal of the operational amplifier U1, the source of the third semiconductor switch Q3, the second terminal of the first resistor R1, and the second terminal of the second resistor R2 are all connected to the first node B.

[0036] The circuit operates as follows: Upon power-up, it defaults to the 2000R range, where A1 and A2 are disabled. Sampling resistors R2 and R3 are connected in series, and the constant current source outputs 0.5mA, suitable for preliminary testing of high resistance values. When the resistor under test is connected to the system, the processor acquires the voltage signal in real time through the analog signal acquisition module and estimates the resistance value. Subsequently, the processor automatically selects the appropriate test range based on the estimated resistance value and adjusts the enabling states of A1 and A2 through the range control module, achieving automatic switching between the sampling resistor and voltage output channels.

[0037] In the 20mR and 200mR ranges, A1 and A2 are both enabled, Q1 and Q2 are turned on, and sampling resistors R1 and R2 are connected in parallel to the circuit. At this time, the constant current source output current is 550mA, and the analog switch S1 selects 1.0V as the voltage output, which is suitable for high current precision measurement of small resistors.

[0038] In the 2R position, only the control terminal A1 is enabled, Q1 is turned on, R1 and R2 continue to work in parallel, but the constant current source output current is adjusted to 250mA, corresponding to a voltage output of 0.5V.

[0039] In the 20R and 200R ranges, only the control terminal A2 is enabled, Q2 is turned on, and only the sampling resistor R2 is connected in the circuit. The constant current source output current in the 20R range is 50mA, and the voltage output is selected as 1.0V by S1; the constant current source output current in the 200R range is 5mA, and the voltage output is selected as 0.1V by S1.

[0040] When entering the 2000R range, control terminals A1 and A2 are both disabled, R2 and R3 are connected in series as sampling resistors, the constant current source output current is 0.5mA, and S1 continues to select 1.0V output voltage.

[0041] This device enables precise control of multiple current levels by enabling different combinations of control terminals A1 and A2. Combined with analog switch S1 to switch different voltage output channels, the system can automatically adjust to the optimal measurement state according to the range of the resistance being measured, thereby ensuring that the entire test process is completed under high precision and high stability conditions, effectively improving the intelligence and reliability of DC resistance testing.

[0042] The above are merely preferred embodiments of this utility model. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A resistor for a constant current source control circuit, characterized in that, The resistor comprises a manganese-copper wire and a metal film resistor connected in parallel. The manganese copper wire has a diameter of 3.5 mm, a length of 41 cm, and a resistance of 2 Ω, while the metal film resistor has a resistance of 1 MΩ.

2. A constant current source control circuit, characterized in that, Includes the resistor as described in claim 1.

3. The constant current source control circuit according to claim 2, characterized in that, The constant current source control circuit includes an operational amplifier, a voltage control module, a first resistor, a second resistor, a third resistor, a first semiconductor switch, a second semiconductor switch, and a third semiconductor switch; The positive terminal of the operational amplifier is connected to the voltage control module, and the voltage control module can control the voltage input to the positive terminal of the operational amplifier. The first end of the second resistor is connected to the first end of the third resistor, and the second end of the third resistor is grounded. The gate of the first semiconductor switch is connected to the first control signal, the drain is connected to the first terminal of the first resistor, and the source is grounded. The gate of the second semiconductor switch is connected to the second control signal, the drain is connected between the second resistor and the third resistor, and the source is grounded to the second end of the third resistor; The gate of the third semiconductor switch is connected to the signal output terminal of the operational amplifier, and the drain is connected to the constant current source signal. The negative terminal of the operational amplifier, the source of the third semiconductor switch, the second terminal of the first resistor, and the second terminal of the second resistor are all connected to the first node; The first resistor is the resistor described in claim 1.

4. The constant current source control circuit according to claim 3, characterized in that, The voltage control module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an analog switch; The fourth resistor, the fifth resistor, the sixth resistor, and the seventh resistor are connected in series to form a resistor string, and their two ends are respectively connected to the positive and negative terminals of the input voltage. The input terminal of the analog switch can be selectively connected to the connection node between adjacent resistors in the resistor string, and the output terminal is connected to the positive signal input terminal of the operational amplifier.

5. The constant current source control circuit according to claim 4, characterized in that, The input voltage of the resistor string is 2.5V; When the input terminal of the analog switch is connected between the fourth resistor and the fifth resistor, the input voltage at the positive terminal of the operational amplifier is 1V. When the input terminal of the analog switch is connected between the fifth resistor and the sixth resistor, the input voltage at the positive terminal of the operational amplifier is 0.5V. When the input terminal of the analog switch is connected between the sixth resistor and the seventh resistor, the input voltage at the positive terminal of the operational amplifier is 0.1V.

6. The constant current source control circuit according to claim 3, characterized in that, The first semiconductor switch, the second semiconductor switch, and the third semiconductor switch are all N-channel field-effect transistors.

Images