High-frequency PWM signal detection circuit

Abstract

The utility model discloses a high-frequency PWM signal detection circuit which comprises a reference source module, a PWM input optocoupler module, a PWM logic detection module and an MCU signal detection module. The reference source module is connected with the PWM input optocoupler module, the PWM logic detection module and the MCU signal detection module; the PWM input optocoupler module is connected with the PWM logic detection module and the MCU signal detection module; and the PWM logic detection module is connected with the MCU signal detection module. The device can be applied to the detection of related electronic boards with high-frequency PWM output, can achieve the detection before the combined test with corollary equipment, and can avoid the damage of a power module of the corollary equipment, the abnormal operation of a motor, and the like.

Description

Technical Field

[0001] This utility model relates to the field of signal modulation technology, and in particular to a high-frequency PWM signal detection circuit. Background Technology

[0002] The main control board of an elevator is responsible not only for detecting elevator-related signals but also for outputting signals to control the motor, ensuring the elevator operates normally. The high-frequency PWM signal output by the main control board to control the motor is extremely important, enabling efficient elevator operation and improving the passenger experience. Currently, most PWM detection circuits on these boards only detect low-frequency PWM signals to check for abnormalities in components. High-frequency PWM signal detection is rarely used, which poses a potential risk in practical high-frequency PWM applications. Abnormal high-frequency PWM signal output can damage other external electronic boards, and in severe cases, cause motor malfunctions and elevator safety accidents. Utility Model Content

[0003] The purpose of this invention is to overcome the problems existing in related technologies and provide a high-frequency PWM signal detection circuit.

[0004] The technical solution adopted by this utility model is:

[0005] A high-frequency PWM signal detection circuit includes a reference source module, a PWM input optocoupler module, a PWM logic detection module, and an MCU signal detection module;

[0006] The reference source module is connected to the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module;

[0007] The PWM input optocoupler module is connected to the PWM logic detection module and the MCU signal detection module; the PWM logic detection module is connected to the MCU signal detection module.

[0008] Furthermore, the reference source module includes a power supply, a reference source chip, and a reference source module resistor; the reference source module resistor includes a first resistor and a second resistor;

[0009] One end of the first resistor is connected to the power supply and the cathode of the reference source chip, and the other end is connected to one end of the second resistor and the reference terminal of the reference source chip;

[0010] The other end of the second resistor is connected to the anode and ground of the reference source chip;

[0011] The reference terminal of the reference source chip is connected to the voltage divider node of the first resistor and the second resistor;

[0012] The anode of the reference source chip is connected to ground;

[0013] The cathode of the reference source chip is connected to the power supply and the load; the load includes the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module.

[0014] Furthermore, the reference source chip is a TL431BIDBZR chip.

[0015] Furthermore, the PWM input optocoupler module includes multiple units, each of which includes an optocoupler chip, a PWM input optocoupler module resistor, and a first capacitor; the PWM input optocoupler module resistor includes a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

[0016] The anode of the optocoupler chip is connected to one end of the third resistor, one end of the first capacitor, and one end of the fourth resistor; the other end of the third resistor is connected to the reference source module; the cathode of the optocoupler chip is connected to the PWM signal input port, the other end of the first capacitor, and the other end of the fourth resistor; the ground terminal of the optocoupler chip is connected to the ground wire; the output terminal of the optocoupler chip is connected to the first end of the fifth resistor and one end of the sixth resistor; the second end of the fifth resistor is connected to the reference source module; the other end of the sixth resistor is connected to the MCU signal detection module; the enable terminal of the optocoupler chip is connected to the reference source module, the second end of the fifth resistor, and the power supply terminal of the optocoupler chip; the power supply terminal of the optocoupler chip is connected to the reference source module and the second end of the fifth resistor.

[0017] Furthermore, the unit of the PWM input optocoupler module also includes a second capacitor;

[0018] One end of the second capacitor is connected to the reference source module, the enable terminal of the optocoupler chip, the power supply terminal of the optocoupler chip, and the second end of the fifth resistor; the other end of the second capacitor is connected to the ground wire.

[0019] Furthermore, the optocoupler chip is a 6N137SDM chip.

[0020] Furthermore, the PWM logic detection module includes an OR gate chip;

[0021] The input terminal of the OR gate chip is connected to the PWM input optocoupler module and the MCU signal detection module;

[0022] The output of the OR gate chip is connected to the MCU signal detection module.

[0023] Furthermore, the OR gate chip is a four-way 2-input OR gate chip.

[0024] Furthermore, the OR gate chip is an SN74HC32PWR chip.

[0025] Furthermore, the MCU signal detection module includes an MCU chip; the MCU chip includes a plurality of first GPIO pins and a plurality of second GPIO pins; the first GPIO pins are connected to the PWM input optocoupler module and the PWM logic detection module; the second GPIO pins are connected to the PWM logic detection module.

[0026] The beneficial effects of this invention are: it provides a high-frequency PWM signal detection circuit, including a reference source module, a PWM input optocoupler module, a PWM logic detection module, and an MCU signal detection module; the reference source module is connected to the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module; the PWM input optocoupler module is connected to the PWM logic detection module and the MCU signal detection module; and the PWM logic detection module is connected to the MCU signal detection module. This invention can be applied to the testing of electronic boards with high-frequency PWM output, enabling testing before combined testing with supporting equipment, thus avoiding damage to the power module of the supporting equipment and abnormal motor operation. Attached Figure Description

[0027] Figure 1 This is a high-frequency PWM signal detection circuit diagram provided in this embodiment of the utility model;

[0028] Figure 2 This is the signal truth table of the PWM logic detection circuit provided in this embodiment of the utility model. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0030] This utility model provides a high-frequency PWM detection circuit; the overvoltage protection circuit is composed as follows: Figure 1 As shown, it includes: reference source module 1, PWM input optocoupler module 2, PWM logic detection module 3, and MCU signal detection module 4.

[0031] The circuit works roughly as follows: the power input VIN outputs a stable reference voltage VCC3.3 through the reference source module 1. The electronic board to be tested outputs PWM-UP, PWM-UN, PWM-VP, PWM-VN, PWM-WP, and PWM-WN (UVW motor drive PWM signals) through the PWM input optocoupler module 2 and then sends the output signal to the MCU signal detection module 4. The MCU internal program determines the duty cycle and frequency of the current PWM input signal. At the same time, the signal output by the PWM optocoupler circuit is sent to the PWM logic judgment module 3, and then the feedback signal is sent to the MCU signal detection module 4 to determine whether the logic of the current PWM output is normal.

[0032] The present invention will be further described in detail below with reference to embodiments and specific implementation methods.

[0033] This utility model provides a high-frequency PWM signal detection circuit, including a reference source module, a PWM input optocoupler module, a PWM logic detection module, and an MCU signal detection module;

[0034] The reference source module is connected to the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module.

[0035] The PWM input optocoupler module is connected to the PWM logic detection module and the MCU signal detection module; the PWM logic detection module is connected to the MCU signal detection module.

[0036] The reference source module disclosed in this embodiment includes a power supply, a reference source chip, and a reference source module resistor; the reference source module resistor includes a first resistor and a second resistor;

[0037] One end of the first resistor is connected to the power supply and the cathode of the reference source chip, and the other end is connected to one end of the second resistor and the reference end of the reference source chip.

[0038] The other end of the second resistor is connected to the anode and ground of the reference source chip;

[0039] The reference terminal of the reference source chip is connected to the voltage divider node of the first and second resistors;

[0040] The anode of the reference source chip is connected to ground;

[0041] The cathode of the reference source chip is connected to the power supply and the load; the load includes a PWM input optocoupler module, a PWM logic detection module, and an MCU signal detection module.

[0042] As an optional implementation, the reference source module provides a stable reference voltage VCC 3.3V, providing a stable operating voltage for the PWM input optocoupler module, MCU signal detection module, and PWM logic detection module. The reference source chip, along with the first and second resistors, performs a voltage divider to output a stable 3.3V voltage.

[0043] The reference source chip disclosed in this embodiment is the TL431BIDBZR chip.

[0044] The PWM input optocoupler module disclosed in this embodiment includes multiple units, each unit including an optocoupler chip, a PWM input optocoupler module resistor, and a first capacitor; the PWM input optocoupler module resistor includes a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

[0045] The anode of the optocoupler chip is connected to one end of the third resistor, one end of the first capacitor, and one end of the fourth resistor; the other end of the third resistor is connected to the reference source module; the cathode of the optocoupler chip is connected to the PWM signal input port, the other end of the first capacitor, and the other end of the fourth resistor; the ground terminal of the optocoupler chip is connected to the ground wire; the output terminal of the optocoupler chip is connected to the first end of the fifth resistor and one end of the sixth resistor; the second end of the fifth resistor is connected to the reference source module; the other end of the sixth resistor is connected to the MCU signal detection module; the enable terminal of the optocoupler chip is connected to the reference source module, the second end of the fifth resistor, and the power supply terminal of the optocoupler chip; the power supply terminal of the optocoupler chip is connected to the reference source module and the second end of the fifth resistor.

[0046] As an optional implementation, the PWM input optocoupler module transmits the high-frequency PWM signals (PWM-UP, PWM-UN, PWM-VP, PWM-VN, PWM-WP, PWM-WN) output by the electronic board to be tested to subsequent circuits (PWM logic detection module and MCU signal detection module) after optocoupler isolation. The optocoupler chip is used to isolate and transmit high-frequency PWM signals. The optocoupler chip has a transmission speed of 10 Mbit / s and is capable of handling high-frequency PWM signals.

[0047] In this diagram, PWM-UP, PWM-VP, and PWM-WP represent the upper arm PWM control signals for the three-phase (U, V, W) motors, while PWM-UN, PWM-VN, and PWM-WN represent the lower arm PWM control signals for the three-phase (U, V, W) motors, respectively. By adjusting the duty cycle and frequency of the PWM signals, the motor's speed, torque, and direction can be controlled.

[0048] The PWM input optocoupler module disclosed in this embodiment also includes a second capacitor;

[0049] One end of the second capacitor is connected to the reference source module, the enable terminal of the optocoupler chip, the power supply terminal of the optocoupler chip, and the second end of the fifth resistor; the other end of the second capacitor is connected to the ground wire.

[0050] The optocoupler chip disclosed in this embodiment is the 6N137SDM chip.

[0051] The PWM logic detection module disclosed in this embodiment includes an OR gate chip;

[0052] The input terminal of the OR gate chip is connected to the PWM input optocoupler module and the MCU signal detection module;

[0053] The output of the OR gate chip is connected to the MCU signal detection module.

[0054] The OR gate chip disclosed in this embodiment is a four-way 2-input OR gate chip.

[0055] The OR gate chip disclosed in this embodiment is the SN74HC32PWR chip.

[0056] As an optional implementation, the PWM logic detection module detects whether the PWM signals of the upper and lower transistors of the same phase are simultaneously low, preventing damage to the power module and abnormal motor operation. An OR gate chip is used for logic judgment. When the signals of the upper and lower transistors of the same phase are detected to be simultaneously low, an error signal is output.

[0057] The MCU signal detection module disclosed in this embodiment includes an MCU chip; the MCU chip includes several first GPIO pins and several second GPIO pins; the first GPIO pins are connected to a PWM input optocoupler module and a PWM logic detection module; the second GPIO pins are connected to the PWM logic detection module.

[0058] As an optional implementation, the MCU signal detection module determines the duty cycle and frequency of the current PWM input signal through the MCU's internal program and compares them with the normal set values ​​to determine whether the PWM signal is abnormal. The MCU chip detects the PWM signal output by the PWM input optocoupler module and calculates the duty cycle and frequency of the PWM signal through the program.

[0059] As an optional implementation, the high-frequency PWM detection circuit of this invention operates in the following ways:

[0060] refer to Figure 1U1 is the reference source chip; R1 is the first resistor; R2 is the second resistor; U2, U3, U4, U5, U6, and U7 are optocoupler chips; R3, R7, R11, R15, R19, and R23 are the third resistors; R4, R8, R12, R16, R20, and R24 are the fourth resistors; R5, R9, R13, R17, R21, and R25 are the fifth resistors; R6, R10, R14, R18, R22, and R26 are the sixth resistors; C1, C4, C7, C10, C13, and C16 are the first capacitors. C2, C5, C8, C11, C14, and C17 are the second capacitors; C3, C6, C9, C12, C15, and C18 are the third capacitors; U2, R3, R4, R5, R6, C1, C2, and C3 form one unit of the PWM input optocoupler module; U8 is an OR gate chip; U8 includes U8A, U8B, U8C, and U8D; U9 is an MCU chip; PA0, PA1, PA2, PA3, PA4, and PA5 are the first GPIO pins, and PA6, PA7, and PA8 are the second GPIO pins.

[0061] Input voltage V IN After voltage division by the reference source chip U1 (TL431BIDBZR) and resistors R1 and R2, the reference source voltage is... VCC3.3 serves as the reference source voltage, providing a stable 3.3V voltage to the PWM input optocoupler module 2, the PWM logic judgment module 3, and the MCU signal detection module 4.

[0062] The optocoupler chip signal in PWM input optocoupler module 2 uses 6N137SDM. This optocoupler chip has a transmission speed of 10Mbit / S and can process the high-frequency PWM signal output by the electronic board that needs to be tested. The PWM signal is essentially a square wave.

[0063] refer to Figure 1 Since the detection circuits for the six input optocouplers (PWM-UP, PWM-UN, PWM-VP, PWM-VN, PWM-WP, and PWM-WN) are identical, the following example uses the PWM-UP optocoupler circuit:

[0064] When the PWM-UP signal is high (3.3V), the voltage values ​​of both the IN+ pin (anode) and IN- pin (cathode) of the optocoupler chip U2 are 3.3V, which cannot reach the primary-side turn-on voltage V of the optocoupler. FAt this time, the optocoupler chip U2 is not connected, and the secondary side Vb pin (output terminal) of the optocoupler chip outputs a signal, which is connected to the PA0 pin of the MCU chip U9 in the circuit of MCU signal detection module 4. At this time, the voltage detected by the PA0 pin is 3.3V; resistor R5 is a pull-up resistor, which provides a high-level signal to the PA0 signal; resistor R6 and capacitor C3 act as an RC filter to provide an accurate input signal for the MCU chip U9 and prevent abnormal signal detection due to external interference during the test; capacitor C2 is for input power filtering of optocoupler chip U2;

[0065] When the PWM-UP signal is low (0V), the voltage at the IN- pin of optocoupler chip U2 is 0V. At this time, the voltage drop between the IN+ and IN- pins of optocoupler chip U2 is... At this time, the primary side of optocoupler chip U2 is turned on, and the Vb pin of U2 outputs a low-level signal. At this time, the voltage detected by the PA0 pin is 0V. The primary side capacitor C1 of optocoupler chip U2 is a filter capacitor and plays a filtering role.

[0066] The above is a breakdown of the principle of a square wave signal in PWM. When PWM is a high-frequency signal, it is composed of many such small square waves. In the MCU signal detection circuit, the high and low level signals collected by the PA0 pin within a unit time of 1 second are judged by the program, thereby calculating the duty cycle and frequency of the PWM. The frequency is compared with that of the original high-frequency PWM signal to determine whether the PWM-UP signal is abnormal.

[0067] Considering that in the daily operation of the power module driving the motor, if the upper transistor signal P and the lower transistor signal N of any phase of the three-phase UVM output high-frequency PWM signal are both at a low level, it will cause damage to the power module and abnormal motor operation. Therefore, a PWM logic detection circuit (PWM logic detection module 3) is needed to detect whether the high-frequency PWM signal output of the upper and lower transistors is abnormal. In the circuit of this module, the detection chip U8 adopts the OR gate chip SN74HC32PWR. The truth table of this circuit is as follows: Figure 2 As shown, when PA6, PA7, and PA8 of the MCU chip U9 detect a low-level signal, an error is reported in a timely manner, which facilitates the screening of abnormal electronic boards by the testing personnel and prevents the electronic boards from being released and causing damage to the power module or abnormal operation of the motor during use.

[0068] This embodiment provides an input optocoupler detection circuit (PWM input optocoupler module 2) for high-frequency PWM detection signals, which can detect whether the output frequency of the PWM is consistent with the normal setting, thus avoiding power module damage and abnormal motor operation caused by one phase abnormality when the three-phase UVW high-frequency PWM signal is output. At the same time, based on the fact that in actual use, when the upper transistor signal P and the lower transistor signal N of any phase of the three-phase UVM output high-frequency PWM signal are both low, it can also lead to power module damage and abnormal motor operation. Therefore, a PWM logic detection circuit (PWM logic detection module 3) is provided to detect whether the upper and lower transistor signals of the same phase are simultaneously outputting low levels.

[0069] In this embodiment, the reference source chip U1 is TL431BIDDZR, and the OR gate chip is SN74HC32PWR. This embodiment only provides a high-frequency PWM signal detection circuit. The specific resistor and capacitor parameters, as well as the selection of chips and transistors, can be designed according to the specific actual application.

[0070] The beneficial effects of this utility model are:

[0071] (1) The high-frequency PWM signal detection circuit of this utility model can be applied to the detection of related electronic boards with high-frequency PWM output. It can perform the test before the equipment is combined with the supporting equipment, which can avoid the damage of the power module of the supporting equipment, abnormal operation of the motor, etc., and ensure the normal operation of the elevator and protect people's life and property safety.

[0072] (2) This utility model can be optimized and improved according to the actual specific PWM output characteristics of electronic boards, and has a wide range of applications;

[0073] (3) The device selected in this utility model has low cost and can save on the cost of testing equipment.

[0074] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high frequency PWM signal detection circuit, characterized by, It includes a reference source module, a PWM input optocoupler module, a PWM logic detection module, and an MCU signal detection module; The reference source module is connected to the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module; The PWM input optocoupler module is connected to the PWM logic detection module and the MCU signal detection module; the PWM logic detection module is connected to the MCU signal detection module.

2. The high-frequency PWM signal detection circuit according to claim 1, characterized in that, The reference source module includes a power supply, a reference source chip, and a reference source module resistor; the reference source module resistor includes a first resistor and a second resistor. One end of the first resistor is connected to the power supply and the cathode of the reference source chip, and the other end is connected to one end of the second resistor and the reference terminal of the reference source chip; The other end of the second resistor is connected to the anode and ground of the reference source chip; The reference terminal of the reference source chip is connected to the voltage divider node of the first resistor and the second resistor; The anode of the reference source chip is connected to ground; The cathode of the reference source chip is connected to the power supply and the load; the load includes the PWM input optocoupler module, the PWM logic detection module, and the MCU signal detection module.

3. The high-frequency PWM signal detection circuit according to claim 2, characterized by The reference source chip is a TL431BIDBZR chip.

4. The high-frequency PWM signal detection circuit according to claim 1, characterized by, The PWM input optocoupler module includes multiple units, each of which includes an optocoupler chip, a PWM input optocoupler module resistor, and a first capacitor; the PWM input optocoupler module resistor includes a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; The anode of the optocoupler chip is connected to one end of the third resistor, one end of the first capacitor, and one end of the fourth resistor; the other end of the third resistor is connected to the reference source module; the cathode of the optocoupler chip is connected to the PWM signal input port, the other end of the first capacitor, and the other end of the fourth resistor; the ground terminal of the optocoupler chip is connected to the ground wire; the output terminal of the optocoupler chip is connected to the first end of the fifth resistor and one end of the sixth resistor; the second end of the fifth resistor is connected to the reference source module; the other end of the sixth resistor is connected to the MCU signal detection module; the enable terminal of the optocoupler chip is connected to the reference source module, the second end of the fifth resistor, and the power supply terminal of the optocoupler chip; the power supply terminal of the optocoupler chip is connected to the reference source module and the second end of the fifth resistor.

5. The high-frequency PWM signal detection circuit according to claim 4, characterized by The unit of the PWM input optocoupler module further includes a second capacitor; One end of the second capacitor is connected to the reference source module, the enable terminal of the optocoupler chip, the power supply terminal of the optocoupler chip, and the second end of the fifth resistor; the other end of the second capacitor is connected to the ground wire.

6. The high-frequency PWM signal detection circuit according to claim 4, characterized by The optocoupler chip is a 6N137SDM chip.

7. The high-frequency PWM signal detection circuit according to claim 1, characterized by, The PWM logic detection module includes an OR gate chip; The input terminal of the OR gate chip is connected to the PWM input optocoupler module and the MCU signal detection module; The output of the OR gate chip is connected to the MCU signal detection module.

8. The high-frequency PWM signal detection circuit according to claim 7, characterized by The OR gate chip is a four-way 2-input OR gate chip.

9. The high-frequency PWM signal detection circuit according to claim 7, characterized by, The or gate chip is an SN74HC32PWR chip.

10. The high-frequency PWM signal detection circuit according to claim 1, characterized by, The MCU signal detection module comprises an MCU chip; the MCU chip comprises a plurality of first GPIO pins and a plurality of second GPIO pins; the first GPIO pins are connected with the PWM input optocoupler module and the PWM logic detection module; the second GPIO pins are connected with the PWM logic detection module.

Images