CN210986081U - Pulse width modulation signal detection device with isolation - Google Patents
Pulse width modulation signal detection device with isolation Download PDFInfo
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- CN210986081U CN210986081U CN201922008822.5U CN201922008822U CN210986081U CN 210986081 U CN210986081 U CN 210986081U CN 201922008822 U CN201922008822 U CN 201922008822U CN 210986081 U CN210986081 U CN 210986081U
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Abstract
The utility model provides a pulse width modulation signal detection device with isolation, which belongs to the technical field of pulse width modulation signal detection, and comprises a MCU, a signal isolation circuit, a communication isolation circuit and a PWM signal input module; the PWM signal input module comprises a voltage conversion circuit, a signal attenuation circuit and a high-speed ADC acquisition circuit; the input end of the signal isolation circuit is connected with the output end of the voltage conversion circuit, and the output end of the signal isolation circuit is connected with the MCU; one end of the communication isolation circuit is connected with the high-speed ADC acquisition circuit, and the other end of the communication isolation circuit is connected with the MCU; and the signal attenuation circuit is connected with the high-speed ADC acquisition circuit. The utility model has the advantages that: the frequency, the duty ratio and the pulse amplitude of the pulse width modulation signal are detected at the same time, and the detection precision and the voltage range are improved.
Description
Technical Field
The utility model relates to a pulse width modulation signal detects technical field, indicates a pulse width modulation signal detection device of area isolation very much.
Background
Pulse Width Modulation (PWM) signals are common control signals in motor control and industrial control of new energy vehicles, and belong to key control signals. If the pwm signal outputted from the controller is not matched with the controller, the controller cannot operate in a predetermined manner, and the controller is damaged, even a safety accident is caused. Therefore, the pwm signal output from the controller needs to be detected.
Conventionally, the following problems exist with respect to detection of a pulse width modulated signal: 1. because the MCU is not isolated from the PWM signal input circuit, interference is easily introduced into the PWM signal, and the detection precision of the MCU and the stability of a system are influenced; 2. because a high-speed ADC acquisition circuit is not arranged to convert the high pulse voltage signal into a digital signal, the pulse amplitude of the PWM signal cannot be detected; 3. because there is no voltage conversion circuit, only the PWM signal with fixed voltage amplitude can be detected, resulting in poor adaptability, and when the voltage amplitude of the input PWM signal is not matched with the voltage of the PWM signal input circuit, the MCU is easily damaged.
Therefore, how to provide an apparatus and a method for detecting a pwm signal with isolation to simultaneously detect the frequency, duty ratio and pulse amplitude of the pwm signal and improve the detection accuracy and voltage range becomes a problem to be solved urgently.
Disclosure of Invention
The to-be-solved technical problem of the utility model lies in providing a pulse width modulation signal detection device who keeps apart in area, realizes detecting pulse width modulation signal's frequency, duty cycle and pulse amplitude simultaneously, and promotes detection precision and voltage range.
The utility model provides a pulse width modulation signal detection device with isolation, which comprises an MCU, a signal isolation circuit, a communication isolation circuit and a PWM signal input module; the PWM signal input module comprises a voltage conversion circuit, a signal attenuation circuit and a high-speed ADC acquisition circuit;
the input end of the signal isolation circuit is connected with the output end of the voltage conversion circuit, and the output end of the signal isolation circuit is connected with the MCU; one end of the communication isolation circuit is connected with the high-speed ADC acquisition circuit, and the other end of the communication isolation circuit is connected with the MCU; and the signal attenuation circuit is connected with the high-speed ADC acquisition circuit.
Further, the signal isolation circuit comprises a digital isolation chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4;
Further, the communication isolation circuit comprises a digital isolation chip U3, a capacitor C6, a capacitor C7, a capacitor C8 and a capacitor C9;
Further, the voltage conversion circuit includes a comparator U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C5, a zener diode VD1, and a diode D1;
Further, the signal attenuation circuit comprises a power amplifier N1, a resistor R8, a resistor R9, a resistor R10, a resistor R11 and a resistor R12;
Further, the high-speed ADC acquisition circuit includes an analog-to-digital converter U5, a reference voltage source chip U4, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C10, a capacitor C11, and a capacitor C12;
The utility model has the advantages that:
1. through setting up signal isolation circuit and communication isolation circuit have avoidd the influence of PWM signal to MCU that has strong interference, very big promotion detection device's detection precision and stability.
2. Through setting up signal attenuation circuit and high-speed ADC acquisition circuit, realize turning into digital signal with PWM's high pulse voltage signal, and then detect the pulse amplitude of PWM signal.
3. Through setting up signal attenuation circuit and voltage conversion circuit, very big promotion detection device's detection voltage range.
4. The PWM signal input module is arranged to carry out voltage conversion and signal conversion on the input PWM signal, and the frequency, the duty ratio and the pulse amplitude of the pulse width modulation signal are detected simultaneously through signal isolation of the signal isolation circuit and the communication isolation circuit.
Drawings
The invention will be further described with reference to the following examples with reference to the accompanying drawings.
Fig. 1 is a schematic block circuit diagram of a pwm signal detection apparatus with isolation according to the present invention.
Fig. 2 is a circuit diagram of the signal isolation circuit of the present invention.
Fig. 3 is a circuit diagram of the communication isolation circuit of the present invention.
Fig. 4 is a circuit diagram of the voltage conversion circuit of the present invention.
Fig. 5 is a circuit diagram of the signal attenuation circuit of the present invention.
Fig. 6 is a circuit diagram of the high-speed ADC acquisition circuit of the present invention.
Fig. 7 is a flow chart of the working principle of the present invention.
Detailed Description
Referring to fig. 1 to 7, a preferred embodiment of a pulse width modulation signal detection device with isolation according to the present invention comprises an MCU, a signal isolation circuit, a communication isolation circuit and a PWM signal input module, wherein the PWM signal input module comprises a voltage conversion circuit, a signal attenuation circuit and a high-speed ADC acquisition circuit, the MCU is used to calculate the frequency, duty ratio and pulse amplitude of a pulse width modulation signal, and in the specific implementation, the MCU capable of implementing the function is selected from the prior art, and is not limited to any model, such as L PC5500 series of MCUs, which can be obtained by a person skilled in the art without creative work, the signal isolation circuit is used to isolate the interference of the PWM signal output from the voltage conversion circuit to the MCU, the communication isolation circuit is used to isolate the interference of the PWM signal output from the high-speed ADC acquisition circuit to the MCU, the voltage conversion circuit is used to convert the PWM signal of a wide voltage range to a PWM signal of a fixed voltage that can be normally acquired by the MCU, so as to ensure the compatibility of the PWM signal with a larger voltage range, and the signal attenuation circuit is used to convert the PWM signal into a PWM signal that the high-speed ADC acquisition is compatible with a high-speed ADC acquisition circuit.
The input end of the signal isolation circuit is connected with the output end of the voltage conversion circuit, and the output end of the signal isolation circuit is connected with the MCU; one end of the communication isolation circuit is connected with the high-speed ADC acquisition circuit, and the other end of the communication isolation circuit is connected with the MCU; and the signal attenuation circuit is connected with the high-speed ADC acquisition circuit. The positive input signal and the negative input signal of the PWM are respectively connected with the voltage conversion circuit and the signal attenuation circuit, so that the frequency, the duty ratio and the pulse amplitude of the pulse width modulation signal can be detected conveniently.
The signal isolation circuit comprises a digital isolation chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; the model of the digital isolation chip U1 is ADUM7641, and the digital isolation chip U1 is used for isolating interference of PWM signals output by the voltage conversion circuit to the MCU;
The communication isolation circuit comprises a digital isolation chip U3, a capacitor C6, a capacitor C7, a capacitor C8 and a capacitor C9; the model of the digital isolation chip U3 is ADUM1411, and is used for isolating the interference of PWM signals output to the MCU by the high-speed ADC acquisition circuit;
The voltage conversion circuit comprises a comparator U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C5, a voltage stabilizing diode VD1 and a diode D1, wherein the comparator U2 is L MV761MA in model and is used for converting PWM signals in a wide voltage range into PWM signals of fixed voltage which can be normally collected by an MCU (microprogrammed control Unit) so as to ensure compatibility with PWM signals in a larger voltage range, the voltage stabilizing diode VD1 is BZT52C5V1W, and the diode D1 is MBRS3200T 3G;
The signal attenuation circuit comprises a power amplifier N1, a resistor R8, a resistor R9, a resistor R10, a resistor R11 and a resistor R12; the model of the power amplifier N1 is OPA 188;
The high-speed ADC acquisition circuit comprises an analog-to-digital converter U5, a reference voltage source chip U4, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C10, a capacitor C11 and a capacitor C12; the model of the analog-to-digital converter U5 is AD7794 BRUZ; the model of the reference voltage source chip U4 is AD780 BR;
The working principle of the utility model comprises the following steps:
step S1, the PWM signal input module performs voltage conversion and signal conversion on the input PWM signal and sends the converted signal to the signal isolation circuit and the communication isolation circuit;
step S2, the signal isolation circuit and the communication isolation circuit send the received signal to the MCU;
and step S3, the MCU detects the frequency, the duty ratio and the pulse amplitude of the PWM signal according to the received signal.
The detection of the frequency and the duty ratio of the PWM signal comprises the following steps:
step S11, the PWM signal is subjected to voltage conversion through a voltage conversion circuit, and the PWM signal after voltage conversion is sent to a signal isolation circuit;
s12, the signal isolation circuit isolates the received signal from interference and sends the signal to the MCU;
step S13, the MCU captures the rising edge and the falling edge of the signal by utilizing the capture function of the self-contained timer, records the clock value t1 for capturing the rising edge for the first time, records the clock value t2 for capturing the falling edge after capturing the rising edge for the first time and records the clock value t3 for capturing the rising edge for the second time; the rising edge, namely the level, is from low to high, and the falling edge, namely the level, is from high to low;
step S14, calculating the frequency and duty ratio of the PWM signal using the t1, t2 and t 3:
frequency of PWM signal: f is 1/(t3-t 1);
the duty ratio of the PWM signal D ═ (t2-t1)/(t3-t 1).
Where f represents the frequency of the PWM signal and D represents the duty cycle of the PWM signal.
The detection of the pulse amplitude of the PWM signal includes the steps of:
s21, attenuating the PWM signal to 1/Gain of the original value through a signal attenuation circuit, converting the attenuated PWM signal from a voltage signal to a digital signal through a high-speed ADC acquisition circuit, and sending the digital signal to a communication isolation circuit, wherein Gain is more than 1;
s22, the digital signal received by the communication isolation circuit is sent to the MCU after being isolated from interference;
step S23, when the MCU detects the rising edge of the digital signal, the level value of the PWM signal currently acquired by the high-speed ADC acquisition circuit is continuously read and stored by using the SPI communication function of the MCU, and the reading is stopped until the MCU detects that the digital signal is the falling edge; the SPI is an abbreviation of a Serial Peripheral Interface (Serial Peripheral Interface), is a high-speed, full-duplex, synchronous communication bus, and occupies only four wires on the pins of the chip, saving the pins of the chip, and providing convenience for saving space on the layout of the PCB, and due to the characteristics of simplicity and easy use, more and more chips integrate the communication protocol;
step S24, selecting the maximum value of the saved level value as v 1;
pulse amplitude of the PWM signal: v1 gas.
Where V represents the pulse amplitude of the PWM signal and Gain represents the multiple of the PWM signal attenuated by the signal attenuation circuit.
To sum up, the utility model has the advantages that:
1. through setting up signal isolation circuit and communication isolation circuit have avoidd the influence of PWM signal to MCU that has strong interference, very big promotion detection device's detection precision and stability.
2. Through setting up signal attenuation circuit and high-speed ADC acquisition circuit, realize turning into digital signal with PWM's high pulse voltage signal, and then detect the pulse amplitude of PWM signal.
3. Through setting up signal attenuation circuit and voltage conversion circuit, very big promotion detection device's detection voltage range.
4. The PWM signal input module is arranged to carry out voltage conversion and signal conversion on the input PWM signal, and the frequency, the duty ratio and the pulse amplitude of the pulse width modulation signal are detected simultaneously through signal isolation of the signal isolation circuit and the communication isolation circuit.
Although specific embodiments of the present invention have been described, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the claims appended hereto.
Claims (6)
1. The utility model provides a pulse width modulation signal detection device of area isolation which characterized in that: comprises an MCU, a signal isolation circuit, a communication isolation circuit and a PWM signal input module; the PWM signal input module comprises a voltage conversion circuit, a signal attenuation circuit and a high-speed ADC acquisition circuit;
the input end of the signal isolation circuit is connected with the output end of the voltage conversion circuit, and the output end of the signal isolation circuit is connected with the MCU; one end of the communication isolation circuit is connected with the high-speed ADC acquisition circuit, and the other end of the communication isolation circuit is connected with the MCU; and the signal attenuation circuit is connected with the high-speed ADC acquisition circuit.
2. The isolated pwm signal detection apparatus according to claim 1, wherein: the signal isolation circuit comprises a digital isolation chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4;
pins 1 and 7 of the digital isolation chip U1 are respectively connected with a capacitor C2 and a capacitor C4, pin 2 is respectively connected with a capacitor C2 and a capacitor C4 and grounded, pins 3, 4, 5, 6 and 9 are respectively connected with a voltage conversion circuit, pins 10 and 11 are grounded, pins 12, 15, 16, 17 and 18 are respectively connected with an MCU, pins 14 and 20 are respectively connected with a capacitor C1 and a capacitor C3, and pin 19 is respectively connected with a capacitor C1 and a capacitor C3 and grounded.
3. The isolated pwm signal detection apparatus according to claim 1, wherein: the communication isolation circuit comprises a digital isolation chip U3, a capacitor C6, a capacitor C7, a capacitor C8 and a capacitor C9;
pins 1 and 7 of the digital isolation chip U3 are respectively connected with a capacitor C6 and a capacitor C8, pin 2 is respectively connected with a capacitor C6 and a capacitor C8 and grounded, pins 3, 4, 5 and 6 are respectively connected with the MCU, pins 8 and 9 are both grounded, pins 10 and 16 are respectively connected with a capacitor C7 and a capacitor C9, pins 11, 12, 13 and 14 are respectively connected with the high-speed ADC acquisition circuit, and pin 15 is respectively connected with a capacitor C7 and a capacitor C9 and grounded.
4. The isolated pwm signal detection apparatus according to claim 1, wherein: the voltage conversion circuit comprises a comparator U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C5, a voltage stabilizing diode VD1 and a diode D1;
pin 2 of the comparator U2 is respectively connected with a capacitor C5, a resistor R6 and a resistor R7, pin 3 is connected with a resistor R2, pin 4 is connected with a capacitor C5 and a resistor R6 and is grounded, pin 5 is connected with a resistor R1, pin 6 is connected with a resistor R4, and pin 7 is connected with a resistor R1; the resistor R4 is connected with the signal isolation circuit; the resistor R2 is respectively connected with the resistor R3, the resistor R5 and the output end of the voltage stabilizing diode VD 1; the resistor R5 is connected with the input end of the voltage stabilizing diode VD1 and is grounded; the resistor R3 is connected to the output of the diode D1.
5. The isolated pwm signal detection apparatus according to claim 1, wherein: the signal attenuation circuit comprises a power amplifier N1, a resistor R8, a resistor R9, a resistor R10, a resistor R11 and a resistor R12;
pin 1 of the power amplifier N1 is respectively connected with a resistor R9 and a resistor R11, pin 3 is respectively connected with a resistor R8 and a resistor R10, and pin 4 is respectively connected with a resistor R11 and a resistor R12; the resistor R9 is connected with the high-speed ADC acquisition circuit; the resistor R10 and the resistor R12 are both grounded.
6. The isolated pwm signal detection apparatus according to claim 1, wherein: the high-speed ADC acquisition circuit comprises an analog-to-digital converter U5, a reference voltage source chip U4, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a capacitor C10, a capacitor C11 and a capacitor C12;
pin 1 of the analog-to-digital converter U5 is connected with a resistor R15 and a communication isolation circuit, pin 3 is connected with a resistor R16 and a communication isolation circuit, pins 6, 8, 10 and 12 are all grounded, pins 7, 9, 11, 15 and 17 are respectively connected with a signal attenuation circuit, pin 13 is connected with a capacitor C11 and pin 6 of a reference voltage source chip U4, pins 14, 16, 18, 19 and 20 are respectively connected with the capacitor 11 and grounded, pin 23 is connected with the resistor R13 and the communication isolation circuit, and pin 24 is connected with a resistor R14 and the communication isolation circuit; pin 2 of the reference voltage source chip U4 is connected with a capacitor C10, and pin 3 is connected with a capacitor C12; the capacitor C10 is connected to the capacitor C12 and the pin 4 of the reference voltage source chip U4 and is grounded.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201922008822.5U CN210986081U (en) | 2019-11-20 | 2019-11-20 | Pulse width modulation signal detection device with isolation |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201922008822.5U CN210986081U (en) | 2019-11-20 | 2019-11-20 | Pulse width modulation signal detection device with isolation |
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| CN210986081U true CN210986081U (en) | 2020-07-10 |
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