0-20 ma current source speed control circuit and motor

Abstract

The present application discloses a 0-20 mA current source speed control circuit and a motor. The 0-20 mA current source speed control circuit comprises a dual-channel op-amp current source circuit, and is characterized by further comprising an input voltage adjustable circuit and an ADC sampling circuit. An output terminal Uin of the input voltage adjustable circuit is connected to a signal input terminal of the dual-channel op-amp current source circuit and a signal input terminal of the ADC sampling circuit, and the ADC sampling circuit and the dual-channel op-amp current source circuit each output one signal. The dual-channel op-amp current source circuit features high accuracy and low costs. The input voltage adjustable circuit enables convenient manual adjustment of the magnitude of an output current of a dual-channel op-amp current source, making operation practical and convenient. By using the ADC sampling circuit, the magnitude of an output current of a constant current source can be learned in real time.

Description

A 0-20mA current source speed control circuit and motor Technical Field

[0001] This application relates to a 0-20mA current source speed regulation circuit and a motor. Background Technology

[0002] Currently, 4-20mA speed control circuits are widely used in industry, with the vast majority of solutions employing high-precision 4-20mA dedicated chips, resulting in high costs. Major manufacturers are seeking solutions that offer lower costs, meet accuracy requirements, and are easily replaceable. To address these issues, a popular approach is to utilize a dual-channel operational amplifier based on an improved 0-20mA current source.

[0003] The dual-channel operational amplifier is based on a 0-20mA speed control circuit improved from the HOWLAND current source. Its circuit structure is shown in Figure 1. R1 is the inverting input resistor of the operational amplifier, R3 is the non-inverting input resistor, resistors R1 and R2 form a negative feedback circuit, and resistors R3 and R4 form a positive feedback circuit. RO is the output resistor of the operational amplifier, RL is the load, and Uin+ and Uin- are the input signals of the operational amplifier. Based on Kirchhoff's laws and the concepts of virtual short and virtual open circuits, the following formula can be obtained:

[0004] This formula shows that the current magnitude is independent of the load size. Therefore, as long as the resistor is selected properly, a precise current source can be obtained. Based on this principle, a stable, high-precision, and low-cost 0-20m speed regulation scheme can be designed.

[0005] Although the above-mentioned dual-channel operational amplifier based on the HOWLAND current source can obtain a stable current source, the current magnitude is fixed and there is no manual adjustment circuit, which has the drawback of being inconvenient to use in practice. Summary of the Invention

[0006] This application proposes a 0-20mA current source speed regulation circuit and motor to solve the technical problem that although the existing dual-channel operational amplifier based on the HOWLAND current source can obtain a stable current source, the current magnitude is fixed and there is no manual adjustment circuit, which makes it inconvenient to use in practice.

[0007] The technical solution of this application is implemented as follows:

[0008] A 0-20mA current source speed regulation circuit includes a dual-channel operational amplifier current source circuit, characterized in that: it further includes an input voltage adjustable circuit and an ADC sampling circuit, the output terminal Uin of the input voltage adjustable circuit is connected to the signal input terminal of the dual-channel operational amplifier current source circuit, the output terminal Uin of the input voltage adjustable circuit is connected to the signal input terminal of the ADC sampling circuit, and the ADC sampling circuit and the dual-channel operational amplifier current source circuit each output one signal.

[0009] Preferably, the adjustable input voltage circuit includes a resistor R6 and a variable resistor R9. The resistor R6 and the variable resistor R9 are connected in series and their two ends are respectively connected to a DC power supply V and ground. The DC power supply V is divided by the resistor R6 and the variable resistor R9 and output to form the output terminal Uin of the adjustable input voltage circuit.

[0010] Preferably, the ADC sampling circuit includes an operational amplifier U1B, resistors R5 and R7, and a capacitor C3. The output terminal Uin of the adjustable input voltage circuit is connected to one input terminal of the operational amplifier U1B. The output terminal of the operational amplifier U1B is divided by resistors R5 and R7 and then used as the output terminal MCU_O. The capacitor C3 is connected in parallel with resistor R7.

[0011] Preferably, the dual-channel operational amplifier current source circuit includes operational amplifier U1A, resistors R10, R20, R30, R40, and R8. The output terminal Uin of the adjustable input voltage circuit is connected to the positive input terminal of operational amplifier U1A through resistor R10. The negative input terminal of operational amplifier U1A is connected to ground through resistor R20. The output terminal of operational amplifier U1A is connected to ground through resistor R30 and load RL. The output terminal of operational amplifier U1A is fed back to the negative input terminal of operational amplifier U1A through resistor R40. The feedback signal between resistor R30 and load RL is connected to the positive input terminal of operational amplifier U1A through resistor R8.

[0012] Preferably, a transistor Q1 is also provided between the output terminal of the operational amplifier U1A and the resistor R30. The base of the transistor Q1 is connected to the output terminal of the operational amplifier U1A, the collector of the transistor Q1 is connected to the +15V power supply, and the emitter of the transistor Q1 is connected to one end of the resistor R30.

[0013] An electric motor includes a motor body and a motor controller. The motor body includes a stator assembly and a rotor assembly. The motor controller includes a 0-20mA speed regulation circuit, a microprocessor, a rotor position detection circuit, and an inverter circuit. The 0-20mA speed regulation circuit adopts the aforementioned 0-20mA current source speed regulation circuit, and the output signals of the ADC sampling circuit and the dual-channel operational amplifier current source circuit are each connected to the signal input terminal of the microprocessor.

[0014] Compared with the prior art, this application has the following advantages:

[0015] 1. The 0-20mA current source speed regulation circuit of this application includes a dual-channel operational amplifier current source circuit, an input voltage adjustable circuit, and an ADC sampling circuit. The dual-channel operational amplifier current source circuit has high accuracy and low cost, and the input voltage adjustable circuit can be easily adjusted manually to adjust the magnitude of the output current of the dual-channel operational amplifier current source. It is practical and convenient to operate. Using the ADC sampling circuit, the magnitude of the output current of the constant current source can be known in real time.

[0016] 2. Other advantages of this application are described in detail in the Embodiments section. Attached Figure Description

[0017] Figure 1 is a circuit diagram of a prior art dual-channel operational amplifier based on a HOWLAND current source;

[0018] Figure 2 is a circuit block diagram of Embodiment 1 of this application;

[0019] Figure 3 is the circuit diagram corresponding to Figure 2;

[0020] Figure 4 is a circuit block diagram of Embodiment 2 of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] As shown in Figures 2 and 3, this embodiment provides a 0-20mA current source speed regulation circuit, including a dual-channel operational amplifier current source circuit. Its features include an adjustable input voltage circuit and an ADC sampling circuit. The output terminal Uin of the adjustable input voltage circuit is connected to the signal input terminal of the dual-channel operational amplifier current source circuit, and the output terminal Uin of the adjustable input voltage circuit is connected to the signal input terminal of the ADC sampling circuit. Both the ADC sampling circuit and the dual-channel operational amplifier current source circuit output one signal.

[0023] The 0-20mA current source speed control circuit of this application includes a dual-channel operational amplifier current source circuit, an adjustable input voltage circuit, and an ADC sampling circuit. The dual-channel operational amplifier current source circuit has high accuracy and low cost, and the adjustable input voltage circuit can be easily adjusted manually to adjust the output current of the dual-channel operational amplifier current source. It is practical and convenient to operate. Using the ADC sampling circuit, the output current of the constant current source can be known in real time.

[0024] Preferably, the adjustable input voltage circuit includes a resistor R6 and a variable resistor R9. The resistor R6 and the variable resistor R9 are connected in series, with their ends connected to a DC power supply V and ground, respectively. The DC power supply V is divided by the resistors R6 and R9, and the output voltage Uin of the adjustable input voltage circuit is formed. By manually adjusting the value of the variable resistor R9, the output current of the dual-channel operational amplifier current source can be adjusted, making operation practical and convenient.

[0025] Preferably, the ADC sampling circuit includes operational amplifier U1B, resistors R5 and R7, and capacitor C3. The output terminal Uin of the adjustable input voltage circuit is connected to one input terminal of operational amplifier U1B. The output terminal of operational amplifier U1B, after being divided by resistors R5 and R7, serves as the output terminal MCU_O. Capacitor C3 is connected in parallel with resistor R7. The value of the output terminal Uin of the adjustable input voltage circuit is transmitted to the microprocessor MCU for ADC sampling after being divided by the output resistors of U1B, allowing for real-time knowledge of the constant current source's output current.

[0026] Preferably, the dual-channel operational amplifier current source circuit includes operational amplifier U1A, resistors R10, R20, R30, R40, and R8. The output terminal Uin of the adjustable input voltage circuit is connected to the positive input terminal of operational amplifier U1A through resistor R10. The negative input terminal of operational amplifier U1A is connected to ground through resistor R20. The output terminal of operational amplifier U1A is connected to ground through resistor R30 and load RL. The output terminal of operational amplifier U1A is fed back to the negative input terminal of operational amplifier U1A through resistor R40. The feedback signal between resistor R30 and load RL is connected to the positive input terminal of operational amplifier U1A through resistor R8.

[0027] By making R10 = R20 = R8 = R40, the load current iL = Uin / R30. Therefore, the range of the adjustable constant current source can be determined by modifying the resistor R30 and adjusting the value of the output terminal Uin of the adjustable input voltage circuit.

[0028] Preferably, a transistor Q1 is also provided between the output terminal of operational amplifier U1A and resistor R30. The base of transistor Q1 is connected to the output terminal of operational amplifier U1A, the collector of transistor Q1 is connected to a +15V power supply, and the emitter of transistor Q1 is connected to one end of resistor R30. Transistor Q1 can amplify the output current of operational amplifier U1A. If the actual circuit output current is not very large, transistor Q1 can be omitted to save costs. If higher precision is required, a dual-channel precision operational amplifier can be selected to improve output accuracy.

[0029] When selecting operational amplifier devices, this application can choose not to use high-precision 4-20mA dedicated chips, thereby reducing the number of external electronic components and lowering manufacturing costs.

[0030] Example 2:

[0031] As shown in Figure 4, this embodiment provides a motor, including a motor body and a motor controller. The motor body includes a stator assembly and a rotor assembly. The motor controller includes a 0-20mA speed regulation circuit, a microprocessor, a rotor position detection circuit, and an inverter circuit. The 0-20mA speed regulation circuit adopts the 0-20mA current source speed regulation circuit described in Embodiment 1. The ADC sampling circuit and the dual-channel operational amplifier current source circuit each output one signal and are connected to the signal input terminal of the microprocessor.

[0032] The 0-20mA current source speed control circuit of this application includes a dual-channel operational amplifier current source circuit, an adjustable input voltage circuit, and an ADC sampling circuit. The dual-channel operational amplifier current source circuit has high accuracy and low cost, and the adjustable input voltage circuit can be easily adjusted manually to adjust the output current of the dual-channel operational amplifier current source. It is practical and convenient to operate. Using the ADC sampling circuit, the output current of the constant current source can be known in real time.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A 0-20mA current source speed regulation circuit, comprising a dual-channel operational amplifier current source circuit, characterized in that: It also includes an adjustable input voltage circuit and an ADC sampling circuit. The output terminal Uin of the adjustable input voltage circuit is connected to the signal input terminal of the dual-channel operational amplifier current source circuit, and the output terminal Uin of the adjustable input voltage circuit is connected to the signal input terminal of the ADC sampling circuit. The ADC sampling circuit and the dual-channel operational amplifier current source circuit each output one signal.

2. The 0-20mA current source speed regulation circuit according to claim 1, characterized in that: The adjustable input voltage circuit includes a resistor R6 and a variable resistor R9. The two ends of the resistor R6 and the variable resistor R9 are connected in series and connected to the DC power supply V and ground, respectively. The DC power supply V is divided by the resistor R6 and the variable resistor R9 and output to form the output terminal Uin of the adjustable input voltage circuit.

3. The 0-20mA current source speed regulation circuit according to claim 2, characterized in that: The ADC sampling circuit includes operational amplifier U1B, resistor R5, resistor R7, and capacitor C3. The output terminal Uin of the adjustable input voltage circuit is connected to one input terminal of operational amplifier U1B. The output terminal of operational amplifier U1B is divided by resistors R5 and R7 and then used as the output terminal MCU_O. Capacitor C3 is connected in parallel with resistor R7.

4. A 0-20mA current source speed regulation circuit according to claim 1, 2, or 3, characterized in that: The dual-channel operational amplifier current source circuit includes operational amplifier U1A, resistors R10, R20, R30, R40, and R8. The output terminal Uin of the adjustable input voltage circuit is connected to the positive input terminal of operational amplifier U1A through resistor R10. The negative input terminal of operational amplifier U1A is connected to ground through resistor R20. The output terminal of operational amplifier U1A is connected to ground through resistor R30 and load RL. The output terminal of operational amplifier U1A is fed back to the negative input terminal of operational amplifier U1A through resistor R40. The feedback signal between resistor R30 and load RL is connected to the positive input terminal of operational amplifier U1A through resistor R8.

5. A 0-20mA current source speed regulation circuit according to claim 4, characterized in that: A transistor Q1 is also placed between the output terminal of op-amp U1A and resistor R30. The base of transistor Q1 is connected to the output terminal of op-amp U1A, the collector of transistor Q1 is connected to +15V power supply, and the emitter of transistor Q1 is connected to one end of resistor R30.

6. An electric motor, comprising a motor body and a motor controller, the motor body comprising a stator assembly and a rotor assembly, the motor controller comprising a 0-20mA speed control circuit, a microprocessor, a rotor position detection circuit, and an inverter circuit, characterized in that: The 0-20mA speed control circuit described herein adopts the 0-20mA current source speed control circuit as described in any one of claims 1 to 5, wherein the output signals of the ADC sampling circuit and the dual-channel operational amplifier current source circuit are each connected to the signal input terminal of the microprocessor.

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