Analog-digital signal conversion circuit suitable for motor speed regulation system and motor controller

Abstract

The utility model discloses an analog-to-digital signal conversion circuit suitable for a motor speed regulation system and a motor controller. A voltage signal and PWM signal conversion circuit comprises a filtering and scaling circuit, a triangular wave generation circuit and a comparison circuit. A motor speed regulation signal TPWM is processed by the PWM signal isolation transmission circuit to output PWM-out, when the input speed regulation signal T0-10V is a voltage signal, the motor speed regulation signal T0-10V is processed by the filtering and scaling circuit and then is input to one input end of the comparison circuit, the triangular wave generation circuit generates a triangular wave with a certain frequency to serve as the other input end of the comparison circuit, and the output end of the comparison circuit is connected with the motor speed regulation signal TPWM. The output end of the comparison circuit outputs PWM-1, and PWM-out is output after the PWM signal isolation transmission circuit processes the PWM-1; the circuit is simple, the principle is easy to understand, conversion of different PWM signal frequencies can be achieved without programming, and the analog-to-digital conversion linearity is good.

Description

Technical Field

[0001] The utility model relates to an analog-to-digital signal conversion circuit and a motor controller suitable for a motor speed regulation system. Background Art

[0002] In the speed control system in the field of industrial control, it is often necessary to control the terminal equipment (such as motors) through analog signals. In order to ensure the safety between input and output and the control signal is not interfered with, the signals at both ends need to be isolated. Therefore, a reliable signal isolation output technology is widely needed.

[0003] At present, there are two main types of signal isolation transmission technologies. One is to achieve the isolation transmission of analog signals through linear optical couplers (such as Figure 1 The other type is to convert the analog voltage signal into PWM through the chip, and then transmit it through ordinary optical couplers for isolation (as shown in Figure 2 shown).

[0004] Linear optocouplers can well isolate and transmit the analog voltage signal input from the primary side to the secondary side, and then sample and process it through the processor on the secondary side. This method is undoubtedly simple in circuit, but in order to obtain an ideal linear signal on the secondary side, the cost of the selected linear optocoupler is also relatively high. There are many analog-to-digital conversion chips on the market that can efficiently convert analog voltage signals into PWM signals. In essence, a small MCU is integrated inside the chip, which converts the voltage into PWM through AD conversion. Because the corresponding program of the chip has been solidified before leaving the factory, users only need to connect it according to the recommended typical application circuit, which really reduces the design workload for downstream users. This is the advantage of integrated circuits, but it also brings application limitations, that is, users cannot freely change the output PWM frequency according to the needs of on-site applications. If the frequency changes, the program needs to be changed, or even the chip with the corresponding frequency needs to be replaced, which will cause some waste of resources. Summary of the invention

[0005] The purpose of the utility model is to provide an analog-to-digital signal conversion circuit and a motor controller suitable for a motor speed regulation system, so as to solve the technical problem that in the prior art, an analog-to-digital conversion chip with an internal MCU is used to convert a voltage signal into a PWM signal. Because the corresponding program of the chip has been solidified before leaving the factory, the user cannot freely change the output PWM frequency according to the application requirements on site. If the frequency is changed, the program needs to be replaced, or even the chip of the corresponding frequency needs to be replaced, thereby causing some technical problems of waste of resources.

[0006] The technical solution of the utility model is achieved in this way:

[0007] An analog-to-digital signal conversion circuit suitable for a motor speed control system, characterized in that it includes a PWM signal isolation transmission circuit and a voltage signal and PWM signal conversion circuit, wherein the voltage signal and PWM signal conversion circuit includes a filtering and scaling circuit, a triangular wave generating circuit and a comparison circuit;

[0008] When the input speed control signal T_PWM is a PWM signal, the motor speed control signal T_PWM is processed by the PWM signal isolation transmission circuit and outputted as PWM-out, where PWM-out is a PWM signal;

[0009] When the input speed control signal T_0-10V is a voltage signal, the motor speed control signal T_0-10V is input to one input end of the comparison circuit after being processed by the filtering and proportional scaling circuit, and the triangle wave generating circuit generates a triangle wave of a certain frequency as the other input end of the comparison circuit, and the output end of the comparison circuit outputs PWM-1, PWM-1 is a PWM signal, and PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out;

[0010] After the above processing, the voltage and PWM different input speed control signals are converted and integrated into the output.

[0011] The above also includes a current-voltage conversion circuit. When the input speed control signal T_4~20mA is a current signal, T_4~20mA outputs a T_0-10V voltage signal through the current-voltage conversion circuit. The T_0-10V voltage signal outputs PWM-1 through the voltage signal and PWM signal conversion circuit. PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out. After the above processing, the three different input speed control signals of voltage, current and PWM are converted and integrated into output.

[0012] The above-mentioned input speed regulation signal T_4-20mA is a current signal of 4-20mA, and the input speed regulation signal T_0-10V is a voltage signal of 0-10V.

[0013] The above-mentioned triangle wave generating circuit includes a comparator U3A, a resistor R18, a resistor R19, a resistor R20, a resistor R25, a resistor R28, a capacitor C9 and a capacitor C7. The frequency of the triangle wave generating circuit can be adjusted by matching the electrical parameters of the capacitor C9 and the resistor R25.

[0014] The above-mentioned filtering and scaling circuit includes resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, capacitor C4, capacitor C5 and diode D1. Resistor R9 and capacitor C4 constitute a filtering circuit, and resistor R8, resistor R9, resistor R10 and resistor R11 constitute a scaling circuit.

[0015] The above-mentioned PWM signal isolation transmission circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a voltage regulator diode DR1 and an optocoupler chip U1.

[0016] The above-mentioned current-to-voltage conversion circuit includes resistor R13, resistor R14, resistor R15, resistor R21, resistor R22, resistor R23, resistor R26, resistor R27, resistor R29, resistor R30, capacitor C6, capacitor C8, capacitor C12, capacitor C11, operational amplifier chip U2A, and operational amplifier chip U2B.

[0017] A motor controller includes a speed control signal input circuit, a microprocessor, and an inverter circuit. The output end of the speed control signal input circuit is connected to the input end of the microprocessor. The invention is characterized in that the speed control signal input circuit is the analog-to-digital signal conversion circuit suitable for the motor speed control system as described above.

[0018] Compared with the prior art, the utility model has the following advantages:

[0019] 1. The circuit is simple, the principle is easy to understand, and the conversion of different PWM signal frequencies can be achieved without programming;

[0020] 2. Good linearity of analog-to-digital conversion;

[0021] 3. Components are common, highly interchangeable, low cost and easy to purchase;

[0022] 4. It can be used in motor speed control circuits and LED dimming circuits in industrial or household appliance fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A circuit diagram for realizing isolated transmission of analog signals through linear optical couplers in the prior art;

[0024] Figure 2 The invention is a circuit diagram of converting an analog voltage signal into a PWM signal through a chip in the prior art.

[0025] Figure 3 It is a circuit block diagram of the first embodiment of the utility model;

[0026] Figure 4 yes Figure 3 The circuit diagram corresponding to the PWM signal isolation transmission circuit;

[0027] Figure 5 yes Figure 3 Circuit diagram corresponding to the medium voltage signal and PWM signal conversion circuit;

[0028] Figure 6 yes Figure 3The circuit diagram corresponding to the current-voltage conversion circuit;

[0029] Figure 7 It is a circuit block diagram of the second embodiment of the utility model. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] Embodiment 1:

[0032] like Figures 3 to 6 As shown, this embodiment provides an analog-to-digital signal conversion circuit suitable for a motor speed control system, characterized in that it includes a PWM signal isolation transmission circuit and a voltage signal and PWM signal conversion circuit, wherein the voltage signal and PWM signal conversion circuit includes a filtering and scaling circuit, a triangular wave generating circuit and a comparison circuit;

[0033] When the input speed control signal T_PWM is a PWM signal, the motor speed control signal T_PWM is processed by the PWM signal isolation transmission circuit and outputted as PWM-out, where PWM-out is a PWM signal;

[0034] When the input speed control signal T_0-10V is a voltage signal, the motor speed control signal T_0-10V is input to one input end of the comparison circuit after being processed by the filtering and proportional scaling circuit, and the triangle wave generating circuit generates a triangle wave of a certain frequency as the other input end of the comparison circuit, and the output end of the comparison circuit outputs PWM-1, PWM-1 is a PWM signal, and PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out;

[0035] After the above processing, the voltage and PWM different input speed control signals are converted and integrated into the output.

[0036] The above-mentioned analog-to-digital signal conversion circuit suitable for the motor speed control system also includes a current-voltage conversion circuit. When the input speed control signal T_4~20mA is a current signal, T_4~20mA outputs a T_0-10V voltage signal through the current-voltage conversion circuit, and the T_0-10V voltage signal outputs PWM-1 through the voltage signal and PWM signal conversion circuit. PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out. After the above processing, the three different input speed control signals of voltage, current and PWM are converted and integrated and output.

[0037] The above-mentioned input speed regulation signal T_4-20mA is a current signal of 4-20mA, and the input speed regulation signal T_0-10V is a voltage signal of 0-10V.

[0038] The above-mentioned triangle wave generating circuit includes a comparator U3A, a resistor R18, a resistor R19, a resistor R20, a resistor R25, a resistor R28, a capacitor C9 and a capacitor C7. The frequency of the triangle wave generating circuit can be adjusted by matching the electrical parameters of the capacitor C9 and the resistor R25.

[0039] The above-mentioned filtering and scaling circuit includes resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, capacitor C4, capacitor C5 and diode D1. Resistor R9 and capacitor C4 constitute a filtering circuit, and resistor R8, resistor R9, resistor R10 and resistor R11 constitute a scaling circuit.

[0040] The above-mentioned PWM signal isolation transmission circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a voltage regulator diode DR1 and an optocoupler chip U1.

[0041] The above-mentioned current-to-voltage conversion circuit includes resistor R13, resistor R14, resistor R15, resistor R21, resistor R22, resistor R23, resistor R26, resistor R27, resistor R29, resistor R30, capacitor C6, capacitor C8, capacitor C12, capacitor C11, operational amplifier chip U2A, and operational amplifier chip U2B.

[0042] The specific working principle of the utility model is as follows: the triangle wave generating circuit includes a comparator U3A, a resistor R18, a resistor R19, a resistor R20, a resistor R25, a resistor R28, a capacitor C9 and a capacitor C7. The frequency of the triangle wave generating circuit can be adjusted by matching the electrical parameters of the capacitor C9 and the resistor R25. The core circuit is as follows Figure 4According to the charging and discharging characteristics of the capacitor, the frequency of the triangular wave can be adjusted by matching the electrical parameters of the capacitor C and the resistor R25; the external input motor speed control signal T_0-10V (voltage signal) is input to one input end of the comparison circuit after being filtered and processed by the proportional scaling circuit. The triangular wave generating circuit generates a triangular wave of a certain frequency as the other input end of the comparison circuit. The output end of the comparison circuit outputs PWM-1, PWM-1 is a PWM signal, and PWM-1 is processed by the PWM signal isolation transmission circuit to output PWM-out.

[0043] The utility model has the following advantages: 1. The circuit is simple, the principle is easy to understand, and the conversion of different PWM signal frequencies can be achieved without programming; 2. The analog-to-digital conversion linearity is good; 3. The components are common, mutually substitutable, low cost, and easy to purchase; 4. It can be applied to motor speed regulation circuits and LED dimming circuits in the fields of industry or household appliances.

[0044] Embodiment 2:

[0045] like Figure 7 As shown, a motor controller includes a speed control signal input circuit, a microprocessor, and an inverter circuit. The output end of the speed control signal input circuit is connected to the input end of the microprocessor. It is characterized in that: the speed control signal input circuit is the analog-to-digital signal conversion circuit suitable for the motor speed control system described in Example 1.

[0046] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention are equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An analog-to-digital signal conversion circuit suitable for a motor speed control system, characterized in that: It includes a PWM signal isolation transmission circuit and a voltage signal and PWM signal conversion circuit, wherein the voltage signal and PWM signal conversion circuit includes a filtering and scaling circuit, a triangular wave generating circuit and a comparison circuit; When the input speed control signal T_PWM is a PWM signal, the motor speed control signal T_PWM is processed by the PWM signal isolation transmission circuit and outputted as PWM-out, where PWM-out is a PWM signal; When the input speed control signal T_0-10V is a voltage signal, the motor speed control signal T_0-10V is input to one input end of the comparison circuit after being processed by the filtering and proportional scaling circuit, and the triangle wave generating circuit generates a triangle wave of a certain frequency as the other input end of the comparison circuit, and the output end of the comparison circuit outputs PWM-1, PWM-1 is a PWM signal, and PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out; After the above processing, the voltage and PWM different input speed control signals are converted and integrated into the output.

2. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 1 is characterized in that: It also includes a current-voltage conversion circuit. When the input speed control signal T_4~20mA is a current signal, T_4~20mA outputs a T_0-10V voltage signal through the current-voltage conversion circuit. The T_0-10V voltage signal outputs PWM-1 through the voltage signal and PWM signal conversion circuit. PWM-1 is processed by the PWM signal isolation transmission circuit and outputs PWM-out. After the above processing, the three different input speed control signals of voltage, current and PWM are converted and integrated and output.

3. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 1 is characterized in that: The input speed control signal T_4~20mA is a current signal of 4~20mA, and the input speed control signal T_0-10V is a voltage signal of 0-10V.

4. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 1, 2 or 3, characterized in that: The triangular wave generating circuit includes a comparator U3A, a resistor R18, a resistor R19, a resistor R20, a resistor R25, a resistor R28, a capacitor C9 and a capacitor C7. The frequency of the triangular wave generating circuit can be adjusted by matching the electrical parameters of the capacitor C9 and the resistor R25.

5. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 4 is characterized in that: The filtering and scaling circuit includes resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, capacitor C4, capacitor C5 and diode D1. Resistor R9 and capacitor C4 constitute a filtering circuit, and resistor R8, resistor R9, resistor R10 and resistor R11 constitute a scaling circuit.

6. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 1, 2 or 3, characterized in that: The PWM signal isolation transmission circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a voltage zener diode DR1 and an optocoupler chip U1.

7. The analog-to-digital signal conversion circuit suitable for a motor speed control system according to claim 3 is characterized in that: The current-voltage conversion circuit includes resistor R13, resistor R14, resistor R15, resistor R21, resistor R22, resistor R23, resistor R26, resistor R27, resistor R29, resistor R30, capacitor C6, capacitor C8, capacitor C12, capacitor C11, operational amplifier chip U2A, and operational amplifier chip U2B.

8. A motor controller, comprising a speed control signal input circuit, a microprocessor, and an inverter circuit, wherein the output end of the speed control signal input circuit is connected to the input end of the microprocessor, and characterized in that: The speed control signal input circuit is an analog-to-digital signal conversion circuit suitable for a motor speed control system as described in any one of claims 1 to 7.

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