CN112398405B - AC motor voltage-regulating and speed-regulating control system and method - Google Patents

Abstract

The invention provides a voltage regulation and speed regulation control system and method for an AC motor, comprising: a micro controller, which is respectively connected with an external control terminal and a rotary encoder of the AC motor, and is used for the given speed and rotation according to the input of the external control terminal. The real-time rotation speed of the AC motor fed back by the encoder generates a pulse modulation signal; the digital-to-analog conversion circuit is connected with the microcontroller to convert the pulse-modulated signal output by the microcontroller into the corresponding analog signal; the AVR microcontroller, which is connected with the digital-to-analog conversion The circuit connection is used to convert the analog signal output by the digital-to-analog conversion circuit into an identifiable digital signal, and generate a speed regulation signal according to the generated digital signal; the voltage regulation circuit is respectively connected with the AVR microcontroller and the AC motor, used for The input power supply voltage of the AC motor is adjusted according to the speed regulation signal generated by the AVR microcontroller, thereby realizing the speed regulation of the AC motor. Based on the fuzzy PID controller, it realizes the on-off control of the thyristor, and then realizes the effective adjustment of the input power voltage and speed of the AC motor, with high precision and strong anti-interference ability.

Description

AC motor voltage regulation and speed regulation control system and method

technical field

The invention relates to the technical field of control, and in particular, to a voltage regulation and speed regulation control system and method for an AC motor.

Background technique

In recent years, AC motors have been widely used in various fields, such as electric vehicles, mechanical lathes, etc. In practical applications, the motor speed regulation (adjusting the speed of the motor) can meet the different needs of the motor load on the speed of the motor. To achieve the purpose of high speed regulation accuracy and wide speed regulation range of the AC motor, the design and research of the speed regulation controller is very important. critical.

In the early days, due to the lack and immaturity of power electronic components, there were very few power electronic devices that could be used to form the AC drive control system, and most of them used analog separation devices. The speed control method of the motor requires many analog devices. Due to the common existence of temperature drift or zero-drift voltage in analog devices, problems such as low precision, large error, and low reliability are directly caused, which seriously affects the production efficiency. With the development of power electronic technology, power electronic devices are developing in the direction of high integration and miniaturization, and the reliability is getting higher and lower, the cost is getting lower and lower, the performance of the AC speed control system has been improved, and the scope of use has continued to expand. However, in the use of new power electronic devices to achieve motor speed regulation, the method of device on-off control is usually more complicated to formulate.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a voltage regulation and speed regulation control system and method for an AC motor, which effectively solves the technical problems of the existing AC motor speed regulation control methods such as low precision, poor reliability, and difficulty in implementation.

The technical scheme provided by the present invention is as follows:

An AC motor voltage regulation and speed regulation control system, comprising:

The microcontroller is connected to the external control terminal and the rotary encoder of the AC motor respectively, and is used to generate a pulse modulation signal according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder;

a digital-to-analog conversion circuit, connected to the microcontroller, for converting the pulse modulation signal output by the microcontroller into a corresponding analog signal;

AVR microcontroller, connected with the digital-to-analog conversion circuit, is used to convert the analog signal output by the digital-to-analog conversion circuit into a recognizable digital signal, and generate a speed control signal according to the generated digital signal;

The voltage regulation circuit is respectively connected with the AVR microcontroller and the AC motor, and is used for adjusting the input power supply voltage of the AC motor according to the speed regulation signal generated by the AVR microcontroller, so as to realize the speed regulation of the AC motor.

The present invention also provides a voltage regulation and speed regulation control method for an AC motor, comprising:

The microcontroller generates a pulse modulation signal according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder;

The digital-to-analog conversion circuit converts the pulse modulation signal output by the microcontroller into a corresponding analog signal;

The AVR microcontroller converts the analog signal output by the digital-to-analog conversion circuit into an identifiable digital signal, and generates a speed control signal according to the generated digital signal;

The voltage regulation circuit adjusts the input power voltage of the AC motor according to the speed regulation signal, thereby realizing the speed regulation of the AC motor.

The present invention also provides a voltage regulation and speed regulation control system and method for an AC motor, a single-phase AC voltage regulation circuit is designed with a thyristor as a switching device, and the on-off control of the thyristor is realized based on a fuzzy PID controller, and then It can effectively adjust the input power voltage and speed of the AC motor, with high precision and strong anti-interference ability. In addition, the combination of microcontroller and AVR microcontroller further improves the stability of system operation and avoids interference and mixed connection during real-time pulse control and signal conversion.

Description of drawings

The preferred embodiments will be described below in a clear and easy-to-understand manner with reference to the accompanying drawings, and the above-mentioned characteristics, technical features, advantages and implementations thereof will be further described.

Fig. 1 is the structure diagram of AC motor voltage regulation and speed regulation control system in the present invention;

Fig. 2 is the voltage regulation circuit diagram in the present invention;

Fig. 3 is the structure diagram of fuzzy control device in the present invention;

FIG. 4 is a flow chart of the control method for voltage regulation and speed regulation of an AC motor according to the present invention.

Reference number:

1-control terminal, 2-microcontroller, 3-digital-analog conversion circuit, 4-AVR microcontroller, 5-voltage regulator circuit, 61-AC motor, 62-rotary encoder, 7-comparator, 8-fuzzy PID controller

Detailed ways

In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts, and obtain other implementations.

As shown in FIG. 1, the AC motor voltage regulation and speed regulation control system provided by the present invention includes: a microcontroller 2, which is respectively connected with the external control terminal 1 and the rotary encoder of the AC motor 61, and is used for inputting according to the external control terminal 1. The given speed and the real-time rotation speed of the AC motor fed back by the rotary encoder 62 generate a pulse modulation signal; the digital-to-analog conversion circuit 3 is connected with the microcontroller 2, and is used to convert the pulse modulation signal output by the microcontroller 2 into a corresponding analog signal The AVR microcontroller 4 is connected with the digital-to-analog conversion circuit 3, and is used to convert the analog signal output by the digital-to-analog conversion circuit 3 into an identifiable digital signal, and generates a speed regulation signal according to the generated digital signal; the voltage regulation circuit 5 , which are respectively connected to the AVR microcontroller 4 and the AC motor 61, and are used to adjust the input power supply voltage of the AC motor according to the speed regulation signal generated by the AVR microcontroller 4, thereby realizing the speed regulation of the AC motor.

In the control system, the specific models of the microcontroller 2 and the AVR microcontroller 4 can be selected according to the actual situation. In theory, as long as the chips that can achieve the purpose of the present invention are included in the scope. In an example, the microcontroller 2 is an 8051 microcontroller, and the AVR microcontroller 4 is an AVR microcontroller. In this example, the external control terminal 1 (PC terminal, etc.) is connected to the communication interface in the 8051 single-chip microcomputer, so that the control terminal 1 can transmit the given speed to the 8051 single-chip microcomputer through the communication interface. After the 8051 single-chip microcomputer receives the given speed and the real-time speed of the AC motor fed back by the rotary encoder, it pulse-modulates it to generate a pulse-modulated signal, and further transmits the pulse-modulated signal to the digital-to-analog conversion circuit 3 to convert the digital signal into analog Signal. The digital-to-analog conversion circuit 3 is connected to the analog-to-digital conversion circuit in the AVR microcontroller to convert the analog signal into a digital signal that can be recognized by the AVR microcontroller, and then the AVR microcontroller further obtains the speed regulation signal (suitable for The pulse width signal of industrial real-time control) is output to the voltage regulator circuit 5 through the port 1, and the voltage regulator circuit 5 realizes the regulation of the input power supply voltage of the AC motor 61, thereby realizing the regulation of the motor speed.

As shown in FIG. 2 , the voltage regulating circuit 5 includes a first thyristor VT ₁ , a second thyristor VT ₂ and a load resistor R, and the first thyristor VT ₁ and the second thyristor VT ₂ are connected in anti-parallel (the first thyristor VT ₁ The anode of the _second thyristor VT2 is connected to the cathode, the cathode of the _first thyristor VT1 is the cathode of the _second thyristor VT2, the cathode is connected to the anode of the second thyristor VT2), wherein one end of the parallel connection is connected to one end of the load resistor R, and the other end of the parallel connection is connected to the other end of the load resistor R. One end is used as the input end of the circuit, and the input is standard single-phase alternating current u ₁ ; the control ends of the first thyristor VT ₁ and the second thyristor VT ₂ are connected to the AVR microcontroller 4, and the voltage at both ends of the load resistor is used as the output of the voltage regulating circuit u _o . During the working process, in the positive half cycle and negative half cycle of the standard single-phase alternating current u ₁ input, the conduction angle α of the first thyristor VT ₁ and the second thyristor VT ₂ is controlled by the speed control signal generated by the AVR microcontroller 4 respectively. , that is, the purpose of adjusting the output voltage of the alternating current can be achieved, which is simple and convenient and has high accuracy.

In order to realize closed-loop control, the microcontroller 2 also includes a fuzzy control device. As shown in FIG. 3 , the comparator 7 is connected to the rotary encoder 62 of the AC motor and the external control terminal 1 respectively, and is used to obtain the value of the AC motor 61 . Real-time rotational speed, and compare it with the given speed; the fuzzy PID controller 8 is respectively connected with the comparator 7, the first thyristor VT ₁ and the second thyristor VT ₂ in the voltage regulating circuit 5, and is used for according to the AC motor 61 The error signal between the real-time speed and the given speed generates a pulse-modulated signal.

In this process, firstly, the given speed V ^* (t) is compared with the actual speed V(t) fed back by the AC motor 61 in a comparator and an error signal E(t) is generated. After that, the error signal E(t) is passed through the fuzzy PID controller 8 to obtain the pulse modulation signal G(t), and the on-off control G(t) is sent to the voltage regulator circuit through the digital-to-analog conversion circuit 3 and the AVR microcontroller 4 In step 5, the on-off of the first thyristor and the second thyristor is controlled to control the output of the voltage regulating circuit 5 to realize the regulation of the AC output voltage. Finally, the adjusted output AC voltage signal C(t) is used as the input power supply voltage of the AC motor 61 , so that the rotation speed of the AC motor 61 can be adjusted by changing the input AC power supply voltage of the AC motor 61 .

As shown in FIG. 4 , the present invention also provides a voltage regulation and speed regulation control method for an AC motor, including:

The S10 microcontroller generates a pulse modulation signal according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder;

The S20 digital-to-analog conversion circuit converts the pulse modulation signal output by the microcontroller into the corresponding analog signal;

The S30 AVR microcontroller converts the analog signal output by the digital-to-analog conversion circuit into a recognizable digital signal, and generates a speed control signal according to the generated digital signal;

The S40 voltage regulation circuit adjusts the input power supply voltage of the AC motor according to the speed regulation signal, thereby realizing the speed regulation of the AC motor.

In the control method, in the control system, the specific models of the microcontroller and the AVR microcontroller can be selected according to actual conditions. In theory, as long as the chips that can achieve the purpose of the present invention are included in the scope. In an example, the microcontroller is an 8051 microcontroller, and the AVR microcontroller is an AVR microcontroller. In this example, the external control terminal (PC terminal, etc.) is connected with the communication interface in the 8051 single-chip microcomputer, so that the control terminal can transmit the given speed to the 8051 single-chip microcomputer through the communication interface. After the 8051 single-chip microcomputer receives the given speed and the real-time speed of the AC motor fed back by the rotary encoder, it pulse-modulates it to generate a pulse-modulated signal, and further transmits the pulse-modulated signal to the digital-to-analog conversion circuit to convert the digital signal into an analog signal. . The digital-to-analog conversion circuit is connected with the analog-to-digital conversion circuit in the AVR microcontroller to convert the analog signal into a digital signal that can be recognized by the AVR microcontroller, and then the AVR microcontroller further obtains the speed control signal (suitable for industrial Real-time control pulse width signal), and output to the voltage regulation circuit through the port, through the voltage regulation circuit to realize the adjustment of the input power supply voltage of the AC motor, and then realize the adjustment of the motor speed.

As shown in FIG. 2 , the voltage regulating circuit includes a first thyristor VT ₁ , a second thyristor VT ₂ and a load resistor R, and the first thyristor VT ₁ and the second thyristor VT ₂ are connected in anti-parallel (the anode of the first thyristor VT ₁ ) The cathode of the _second thyristor VT2 is connected to the cathode of the _first thyristor VT1, the cathode of the _second thyristor VT2 is connected to the anode of the second thyristor), wherein one end of the parallel connection is connected to one end of the load resistor R, and the other end of the parallel connection is connected to the other end of the load resistor R. As the input end of the circuit, and the input is standard single-phase alternating current u ₁ ; the control ends of the first thyristor VT ₁ and the second thyristor VT ₂ are connected to the AVR microcontroller 4, and the voltage across the load resistor is used as the output u of the voltage regulating circuit _o . During the working process, in the positive half cycle and the negative half cycle of the standard single-phase alternating current u ₁ input, the conduction angle α of the first thyristor VT ₁ and the second thyristor VT ₂ is controlled by the speed control signal generated by the AVR microcontroller, respectively. That is, the purpose of adjusting the output voltage of the alternating current can be achieved, which is simple and convenient and has high accuracy.

The pulse modulation signal generated by the microcontroller according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder includes: the comparator obtains the real-time speed of the AC motor and compares it with the given speed; fuzzy The PID controller generates a pulsed modulation signal based on the error signal between the real-time speed of the AC motor and the given speed.

In this process, first, the given speed V ^* (t) is compared with the actual speed V(t) fed back by the AC motor in a comparator and an error signal E(t) is generated. After that, the error signal E(t) is passed through the fuzzy PID controller to obtain the on-pulse modulation signal G(t), and the on-off control G(t) is sent to the voltage regulation circuit through the digital-to-analog conversion circuit and the AVR microcontroller. The on-off of the first thyristor and the second thyristor is controlled to control the output of the voltage regulating circuit and realize the regulation of the AC output voltage. Finally, the adjusted output AC voltage signal C(t) is used as the input power supply voltage of the AC motor, so that the speed of the AC motor can be adjusted by changing the input AC power supply voltage of the AC motor.

It should be noted that the above embodiments can be freely combined as required. The above are only the preferred embodiments of the present invention. It should be pointed out that, for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as It is the protection scope of the present invention.

Claims (6)

1. an AC motor voltage regulation and speed regulation control system, is characterized in that, comprises: The microcontroller is connected to the external control terminal and the rotary encoder of the AC motor respectively, and is used to generate a pulse modulation signal according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder; a digital-to-analog conversion circuit, connected to the microcontroller, for converting the pulse modulation signal output by the microcontroller into a corresponding analog signal; AVR microcontroller, connected with the digital-to-analog conversion circuit, is used to convert the analog signal output by the digital-to-analog conversion circuit into a recognizable digital signal, and generate a speed control signal according to the generated digital signal; A voltage regulation circuit, which is respectively connected with the AVR microcontroller and the AC motor, and is used for adjusting the input power supply voltage of the AC motor according to the speed regulation signal generated by the AVR microcontroller, thereby realizing the speed regulation of the AC motor; The voltage regulating circuit includes a first thyristor, a second thyristor and a load resistor, wherein the first thyristor and the second thyristor are connected in anti-parallel, one end in parallel is connected with one end of the load resistor, and the other end in parallel and the other end of the load resistor as the input end of the circuit, and the input is standard single-phase alternating current; the control ends of the first thyristor and the second thyristor are connected to the AVR microcontroller, and the voltage across the load resistor is used as a regulator. output of the voltage circuit. 2. The AC motor voltage regulation and speed regulation control system according to claim 1, wherein the microcontroller also includes a fuzzy control device, comprising: The comparator is connected with the rotary encoder of the AC motor and the external control terminal respectively, and is used to obtain the real-time speed of the AC motor and compare it with the given speed; The fuzzy PID controller is respectively connected with the comparator, the first thyristor and the second thyristor in the voltage regulating circuit, and is used for generating a pulse-on modulation signal according to the error signal between the real-time rotation speed of the AC motor and the given speed. 3. The AC motor voltage regulation and speed regulation control system according to claim 1, wherein the microcontroller is an 8051 single-chip microcomputer. 4. A voltage regulation and speed regulation control method for an AC motor, characterized in that, comprising: The microcontroller generates a pulse modulation signal according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder; The digital-to-analog conversion circuit converts the pulse modulation signal output by the microcontroller into a corresponding analog signal; The AVR microcontroller converts the analog signal output by the digital-to-analog conversion circuit into an identifiable digital signal, and generates a speed control signal according to the generated digital signal; The voltage regulation circuit adjusts the input power supply voltage of the AC motor according to the speed regulation signal, thereby realizing the speed regulation of the AC motor; The voltage regulating circuit includes a first thyristor, a second thyristor and a load resistor, wherein the first thyristor and the second thyristor are connected in anti-parallel, one end in parallel is connected with one end of the load resistor, and the other end in parallel and the other end of the load resistor as the input end of the circuit, and the input is standard single-phase alternating current; the control ends of the first thyristor and the second thyristor are connected to the AVR microcontroller, and the voltage across the load resistor is used as a regulator. output of the voltage circuit. 5. The AC motor voltage regulation and speed regulation control method according to claim 4, characterized in that, The pulse modulation signal generated by the microcontroller according to the given speed input from the external control terminal and the real-time speed of the AC motor fed back by the rotary encoder includes: The comparator obtains the real-time speed of the AC motor and compares it with the given speed; The fuzzy PID controller generates a pulsed modulation signal according to the error signal between the real-time speed of the AC motor and the given speed. 6 . The voltage and speed regulation control method of an AC motor according to claim 4 , wherein the microcontroller is an 8051 single-chip microcomputer. 7 .

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