PWM waveform generation circuit detection and application training device

Abstract

The utility model relates to detection and application training equipment for a PWM waveform generation circuit, which realizes cognitive training and examination of a corresponding PWM waveform generation principle circuit through reasonable design of a circuit and a cover plate, realizes on-off of different fault switches through control of a control switch, achieves setting of different fault states for the PWM waveform generation principle circuit, and improves the reliability of the PWM waveform generation circuit. The basic principle, use and troubleshooting of the PWM waveform generation principle circuit can be learned, the fault type and the fault number can be freely set through the state combination of the control switch, the flexibility is good, the operation is convenient, autonomous training and examination are facilitated, the cover plate is opened during training, the function control area is covered during examination, and the operation is convenient. The questioner sets different faults according to the questions, and the examinee identifies the fault occurrence position and reason according to the data parameters detected on the circuit, and finally compares the fault occurrence position and reason with the state of the operation switch of the function control area, so that instant examination can be carried out.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronic technology training equipment, in particular to a PWM waveform generation circuit detection and application training equipment. Background Art

[0002] Power electronics technology spans three fields: power, electronics, and control. It is one of the foundations of modern electronic technology and has been widely used in various fields of ship weapons and equipment. Almost all high-tech fields related to power and electronics on ships involve power electronics conversion and control technology. Therefore, power electronics technology is the basic knowledge and basic skills that electricians and maintenance personnel of similar professions must possess. Operators are required to be able to operate equipment related to power electronics equipment in a standardized manner, and to locate, detect and eliminate faults in a timely manner in case of faults to ensure the normal operation of equipment.

[0003] Usually, when operating and troubleshooting equipment using power electronics technology, it involves comprehensive knowledge of component identification and detection, power electronics schematic analysis, use of electrical tools and instruments, and component replacement, which are essential skills required for maintenance and support work by relevant professionals. Power electronic devices, working principles, and wiring are complex, and operators need a lot of practical troubleshooting experience to accurately and quickly troubleshoot. However, it is obviously inappropriate to conduct maintenance operation training on actual ship devices, which limits the improvement of the troubleshooting ability of power electronic devices.

[0004] PWM waveform (Pulse width modulation wave), PWM is pulse width modulation, that is, a pulse waveform with a variable duty cycle. Pulse width modulation is a method of digitally encoding analog signal levels. It is necessary for operators to understand the working principle of the PWM waveform generation circuit and be able to independently handle the faults of the PWM waveform generation circuit and be able to independently troubleshoot through the occurrence of typical faults. However, there is currently no corresponding training equipment to train and assess related technologies and capabilities. Utility Model Content

[0005] Based on the above description, the utility model provides a PWM waveform generating circuit detection and application training device to solve the above technical problems.

[0006] The technical solution of the utility model to solve the above technical problems is as follows:

[0007] A PWM waveform generating circuit detection and application training device, comprising a circuit board and a cover plate;

[0008] The circuit board has a front side and a back side facing each other, and the front side is provided with a circuit area and a function control area at intervals;

[0009] A PWM waveform generating principle circuit is arranged on the front side corresponding to the circuit area, and a plurality of fault switches electrically connected to the PWM waveform generating principle circuit are arranged on the back side of the circuit area. Different fault states can be formed for the PWM waveform generating principle circuit by turning on and off the fault switches, and the function control area has a control switch for controlling the fault switch.

[0010] The cover plate can selectively cover the function control area.

[0011] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0012] The detection application training device provided in the present application realizes cognitive training and assessment of the PWM waveform generation principle circuit through the reasonable design of the circuit and the cover plate, realizes the opening and closing of different fault switches through the control of the control switch, and sets different fault states for the PWM waveform generation principle circuit, thereby realizing the learning of the basic principle, use and troubleshooting of the PWM waveform generation principle circuit, and the fault type and number can be freely set by the state combination of the control switch. It has good flexibility and easy operation, and is convenient for independent training and assessment. During training, the cover plate is opened, and during assessment, the function control area is covered. The question setter sets different faults according to the questions, and the examinee identifies the location and cause of the fault according to the data parameters detected on the circuit, and finally compares it with the state of the operating switch in the function control area to conduct an immediate assessment.

[0013] On the basis of the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, the PWM waveform generation principle circuit includes a direct current generation circuit, a triangle wave generation circuit, and a PWM wave output circuit;

[0015] The DC power generation circuit is used to generate DC power with adjustable voltage;

[0016] The triangular wave generating circuit is used to generate a triangular wave with adjustable frequency and amplitude;

[0017] The PWM wave output circuit is used to compare the direct current and the triangle wave, and output a PWM square wave according to the comparison result.

[0018] Furthermore, the DC power generating circuit includes a voltage-dividing resistor, a variable resistor and a voltage stabilizing module, the voltage-dividing resistor is connected in series between a predetermined voltage input terminal and a first fixed terminal of the variable resistor, the second fixed terminal is grounded, the sliding terminal of the variable resistor is connected to a DC power output terminal, and the voltage stabilizing module includes a first electrolytic capacitor and a first ceramic capacitor connected in parallel, and the positive electrode of the first electrolytic capacitor is connected to the first fixed terminal.

[0019] Furthermore, the triangle wave generating circuit includes an OP297 operational amplifier having 8 pins, and the pins of the operational amplifier are connected as follows:

[0020] Pin 8 and pin 4 are connected to the positive and negative poles of the power supply respectively, pin 2 and pin 5 are grounded, pin 1 is divided into a first path and a second path, both of which are connected to the triangular wave output end, the first path includes a first potentiometer and is feedback connected to pin 3, the second path includes a second potentiometer and is feedback connected to pin 6, a filter capacitor is connected to the second path, a fixed terminal of the second potentiometer is connected in series with two voltage regulators and then grounded, pin 7 is connected to the triangular wave output end and is feedback connected to pin 6.

[0021] Furthermore, the PWM wave output circuit includes an LM111 comparator having 8 pins, and the pins of the comparator are connected as follows:

[0022] Pin 1 is grounded, pins 5 and 6 are left vacant, pin 2 receives the DC power output from the DC power output terminal, pin 3 receives the triangular wave output from the triangular wave output terminal, pins 8 and 4 are connected to the positive and negative poles of the power supply respectively, pin 7 is connected to the PWM waveform output terminal, and a pull-up resistor is connected between the triangular wave output terminal and the PWM waveform output terminal.

[0023] Furthermore, two passive filtering circuits are included, and the two passive filtering circuits are respectively used close to the operational amplifier and the comparator.

[0024] Furthermore, the fault switch includes an open circuit fault switch and a short circuit fault switch. The open circuit fault switch is used to open the circuit of the corresponding component, and the short circuit fault switch is used to short circuit the corresponding component.

[0025] Further, the circuit breaker fault switch includes a first switch connected between the variable resistor and the DC output terminal, a second switch connected to the adjustable tap of the variable resistor, a third switch connected to the adjustable tap of the first potentiometer, a fourth switch connected to the adjustable tap of the second potentiometer, a fifth switch connected between the positive pole of the power supply voltage and pin 8 of the operational amplifier, a sixth switch connected between pin 7 of the operational amplifier and the triangular wave output terminal, a seventh switch connected between the DC output terminal and pin 2 of the comparator, an eighth switch connected between the triangular wave output terminal and pin 3 of the comparator, a ninth switch connected between the power supply voltage and pin 8 of the comparator, and a tenth switch connected between pin 7 of the comparator and the PWM waveform output terminal;

[0026] The short-circuit fault switch includes an eleventh switch connected in parallel to both ends of the variable resistor, a twelfth switch connected in parallel to the two fixed ends of the first potentiometer, a thirteenth switch connected between pins 2 and 3 of the operational amplifier, a fourteenth switch connected in parallel to the two fixed ends of the second potentiometer, and a fifteenth switch connected to pins 2 and 3 of the comparator. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of the present application;

[0028] Figure 2 A schematic diagram of a PWM waveform generation principle circuit in an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of a direct current generating circuit in an embodiment of the present application;

[0030] Figure 4 Schematic diagram of a triangle wave generating circuit in an embodiment of the present application;

[0031] Figure 5 Schematic diagram of a PWM wave output circuit in an embodiment of the present application;

[0032] Figure 6 Schematic diagram of a passive filtering circuit in an embodiment of the present application;

[0033] Figure 7 Schematic diagram of the arrangement of the fault switch in the embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0036] It will be appreciated that spatial relationship terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, the element or feature described as "under other elements" or "under it" or "under it" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0037] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. The "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0038] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0039] like Figure 1 Combination Figure 2 As shown, an embodiment of the present application provides a PWM waveform generating circuit detection and application training device, which includes a circuit board 10 and a cover plate 20.

[0040] The circuit board 10 has a front side 11 and a back side (not shown) opposite to each other. The front side 11 is provided with a circuit area 11 a and a function control area 11 b at intervals.

[0041] Among them, the circuit area 11a is provided with a PWM waveform generating principle circuit 30 corresponding to the front side 11, and the back side of the circuit area 11a has a plurality of fault switches 40 electrically connected to the PWM waveform generating principle circuit 30. Different fault states can be formed for the PWM waveform generating principle circuit 30 through the on and off combination of the fault switches 40. The function control area 11b has a control switch 12 for controlling the fault switch 40.

[0042] The cover plate 20 can selectively cover the function control area 11b.

[0043] like Figure 2 As shown, the PWM waveform generating principle circuit 30 includes a direct current generating circuit 31 , a triangle wave generating circuit 32 , and a PWM wave output circuit 33 .

[0044] The DC power generating circuit 31 is used to generate DC power with adjustable voltage.

[0045] Specifically, the DC power generation circuit 31 includes a voltage dividing resistor GDR1, a variable resistor GDRJ and a voltage stabilizing module, such as Figure 3 As shown, the voltage-dividing resistor GDR1 is connected in series between the predetermined voltage input terminal and the first fixed terminal of the variable resistor GDRJ, the second fixed terminal of the variable resistor GDRJ is grounded, the sliding terminal of the variable resistor GDRJ is connected to the DC output terminal GD, and the voltage stabilizing module includes a first electrolytic capacitor GDC1 and a first ceramic capacitor GDC2 connected in parallel, the positive electrode of the first electrolytic capacitor GDC1 is connected to the first fixed terminal, and the voltage of the DC power can be adjusted by adjusting the variable resistor GDRJ.

[0046] The triangle wave generating circuit 32 is used to generate a triangle wave with adjustable frequency and amplitude;

[0047] The triangle wave generating circuit 32 includes an OP297 operational amplifier U1, such as Figure 4 As shown, the operational amplifier U1 has 8 pins, and the pins of the operational amplifier U1 are connected as follows:

[0048] Pin 8 and pin 4 are connected to the positive and negative poles of the power supply respectively, pin 2 and pin 5 are grounded, pin 1 is divided into the first path and the second path, both of which are connected to the triangular wave output terminal U1OUT, the first path includes the first potentiometer U1RJ2 and is feedback connected to pin 3, the second path includes the second potentiometer U1RJ1 and is feedback connected to pin 6, the second path is connected to the filter capacitor U1C5, a fixed terminal of the second potentiometer U1RJ1 is connected to the ground after being connected in series with two voltage regulators U1D1 and U1D2, pin 7 is connected to the triangular wave output terminal U1OUT and is feedback connected to pin 6, and the amplitude and frequency of the triangular wave are adjusted by adjusting the first potentiometer U1RJ2 and the second potentiometer U1RJ1.

[0049] Among them, the PWM wave output circuit is used to compare direct current and triangular wave, and output PWM square wave according to the comparison result.

[0050] Specifically, the PWM wave output circuit includes an LM111 comparator U2, which has 8 pins. The pins of the comparator are connected as follows:

[0051] Pin 1 is grounded, pins 5 and 6 are vacant, pin 2 receives the DC power output by the DC output terminal GD, pin 3 receives the triangular wave output by the triangular wave output terminal U1OUT, a first resistor U2R3 is connected between the DC output terminal GD and pin 2, a second resistor U2R4 is connected between the triangular wave output terminal U1OUT and pin 3, pins 8 and 4 are connected to the positive and negative poles of the power supply respectively, pin 7 is connected to the PWM waveform output terminal PWM, and a pull-up resistor U2R1 is connected between the triangular wave output terminal and the PWM waveform output terminal to pull up the level.

[0052] In order to ensure the stability of the above-mentioned PWM waveform output, two passive filtering circuits 34 are also included. The two passive filtering circuits are used close to the operational amplifier U1 and the comparator U2 respectively. As a commonly used passive filtering circuit, it includes a first filtering branch composed of a second electrolytic capacitor U1C1 and a second ceramic capacitor U1C2 and a second filtering branch composed of a third electrolytic capacitor U1C3 and a second ceramic capacitor U1C4. The first filtering branch and the second filtering branch are connected in parallel, and the negative electrode of the second electrolytic capacitor U1C1 and the positive electrode of the third electrolytic capacitor U1C3 are grounded.

[0053] In an embodiment of the present application, the fault switch includes an open circuit fault switch and a short circuit fault switch. The open circuit fault switch is used to open the circuit of the corresponding component, and the short circuit fault switch is used to short-circuit the corresponding component.

[0054] Specifically, Figure 7 As shown, the circuit breaker fault switch includes a first switch SW1 connected between the variable resistor GDRJ and the DC output terminal GD, a second switch SW2 connected to the adjustable tap of the variable resistor GDRJ, a third switch SW3 connected to the adjustable tap of the first potentiometer U1RJ2, a fourth switch SW4 connected to the adjustable tap of the second potentiometer U1RJ1, a fifth switch SW5 connected between the positive pole of the power supply voltage and the No. 8 pin of the operational amplifier U1, a sixth switch SW6 connected between the No. 7 pin of the operational amplifier U1 and the triangular wave output terminal U1OUT, a seventh switch SW7 connected between the DC output terminal GD and the No. 2 pin of the comparator U2, an eighth switch SW8 connected between the triangular wave output terminal U1OUT and the No. 3 pin of the comparator U2, a ninth switch SW9 connected between the power supply voltage and the No. 8 pin of the comparator U2, and a tenth switch SW10 connected between the No. 7 pin of the comparator U2 and the PWM waveform output terminal PWM;

[0055] The short-circuit fault switch includes an eleventh switch SW11 connected in parallel to both ends of the variable resistor GDRJ, a twelfth switch SW12 connected in parallel to the two fixed ends of the first potentiometer U1RJ2, a thirteenth switch SW13 connected between pins 2 and 3 of the operational amplifier U1, a fourteenth switch SW14 connected in parallel to the two fixed ends of the second potentiometer U1RJ1, and a fifteenth switch SW15 connected to pins 2 and 3 of the comparator U2.

[0056] According to the above detection and application training equipment, the fault points, fault images and fault causes can be set as follows:

[0057] 1. SW1

[0058] 1. Fault setting point: the main line between GD and the positive pole of GDC1.

[0059] 2. Description of fault phenomenon: GD signal cannot be output effectively.

[0060] 3. Cause of the fault: The main line between GD and the positive pole of GDC1 is broken.

[0061] SW2

[0062] 1. Fault setting point: between the adjustable tap of the adjustable potentiometer GDRJ and the ground.

[0063] 2. Description of fault phenomenon: GD output voltage cannot be adjusted.

[0064] 3. Cause of the fault: There is a short circuit between the adjustable tap of the adjustable potentiometer GDRJ and the ground.

[0065] SW3

[0066] 1. Fault setting point: between the adjustable tap of U1RJ2 and U1R1.

[0067] 2. Fault phenomenon description: It is impossible to change the peak-to-peak value of the U1OUT output waveform by adjusting U1RJ2. When the circuit is powered on, the oscilloscope screen cannot display a stable waveform when measuring the output of the triangle wave circuit using an oscilloscope.

[0068] 3. Cause of the fault: The circuit between the adjustable tap of U1RJ2 and U1R1 is broken.

[0069] SW4

[0070] 1. Fault setting point: between the adjustable tap of U1RJ1 and the negative pole of U1D2.

[0071] 2. Fault phenomenon description: The frequency of the U1OUT output waveform cannot be changed by adjusting U1RJ1. When the circuit is powered on, the oscilloscope screen cannot display a stable waveform when measuring the output of the triangle wave circuit using an oscilloscope.

[0072] 3. Cause of the fault: There is a short circuit between the adjustable tap of U1RJ1 and the negative pole of U1D2.

[0073] SW5

[0074] 1. Fault setting point: between pin 8 of operational amplifier U1 and ground.

[0075] 2. Description of the fault phenomenon: Operational amplifier U1 cannot work normally, and the triangle wave circuit has no normal output.

[0076] 3. Cause of failure: between pin 8 of operational amplifier U1 and ground.

[0077] SW6

[0078] 1. Fault set point: U1OUT to pin 7 of operational amplifier U1.

[0079] 2. Fault phenomenon description: U1OUT has no signal output.

[0080] 3. Cause of the fault: The main line from U1OUT to pin 7 of the operational amplifier U1 is broken.

[0081] SW7

[0082] 1. Fault setting point: between A and U2R3.

[0083] 2. Description of the fault phenomenon: There is no signal input to the second pin of the comparator U2, and the PWM wave cannot be generated normally.

[0084] 3. Cause of failure: open circuit between A and U2R3.

[0085] SW8

[0086] 1. Fault setting point: between B and U2R4.

[0087] 2. Description of the fault phenomenon: There is no signal input to the third pin of the comparator U2, and the PWM wave cannot be generated normally.

[0088] 3. Cause of failure: open circuit between A and U2R3.

[0089] SW9

[0090] 1. Fault setting point: between pin 8 of LM311 and power supply.

[0091] 2. Fault phenomenon description: LM311 cannot work normally and PWM wave cannot be generated normally.

[0092] 3. Cause of failure: There is a short circuit between the 8th pin of LM311 and the power supply.

[0093] SW10

[0094] 1. Fault setting point: between PWM test point and U2R2.

[0095] 2. Description of fault phenomenon: PWM wave cannot be output.

[0096] 3. Cause of failure: open circuit between PWM test point and U2R2.

[0097] SW11

[0098] 1. Fault setting point: both ends of the fixed resistance of the adjustable potentiometer GDRJ.

[0099] 2. Description of fault phenomenon: GD output is always zero.

[0100] 3. Cause of the fault: Both ends of the fixed resistance of the adjustable potentiometer GDRJ are short-circuited.

[0101] SW12

[0102] 1. Fault setting point: both ends of the fixed resistance of the adjustable potentiometer U1RJ2.

[0103] 2. Fault phenomenon description: U1OUT cannot output triangle wave.

[0104] 3. Cause of the fault: Both ends of the fixed resistance of the adjustable potentiometer U1RJ2 are short-circuited.

[0105] SW13

[0106] 1. Fault setting point: between pins 2 and 3 of operational amplifier U1.

[0107] 2. Fault phenomenon description: U1OUT output is abnormal.

[0108] 3. Cause of the fault: Pin 2 and pin 3 of operational amplifier U1 are short-circuited.

[0109] SW14

[0110] 1. Fault setting point: both ends of the fixed resistance of the adjustable potentiometer U1RJ1.

[0111] 2. Description of fault phenomenon: The frequency of U1OUT output waveform cannot be adjusted by adjusting U1RJ1.

[0112] 3. Cause of the fault: Both ends of the fixed resistance of the adjustable potentiometer U1RJ1 are short-circuited.

[0113] SW15

[0114] 1. Fault setting point: between pins 2 and 3 of comparator U2.

[0115] 2. Description of fault phenomenon: Comparator U2 cannot output PWM waveform normally.

[0116] 3. Cause of failure: The 2nd and 3rd pins of comparator U2 are short-circuited.

[0117] To summarize, the detection application training device provided by the present application realizes cognitive training and assessment of the corresponding PWM waveform generation principle circuit through the reasonable design of the circuit and the cover plate, realizes the opening and closing of different fault switches through the control of the control switch, and sets different fault states for the PWM waveform generation principle circuit, thereby realizing the learning of the basic principle, use and troubleshooting of the PWM waveform generation principle circuit. The fault type and number of faults can be freely set by the state combination of the control switch. It has good flexibility and easy operation, and is convenient for independent training and assessment. During training, the cover plate is opened, and during assessment, the function control area is covered. The question setter sets different faults according to the questions, and the examinee identifies the location and cause of the fault based on the data parameters obtained by detecting the circuit, and finally compares it with the state of the operating switch in the function control area to conduct an immediate assessment.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A PWM waveform generating circuit detection and application training device, characterized in that: Including circuit board and cover; The circuit board has a front side and a back side facing each other, and the front side is provided with a circuit area and a function control area at intervals; The circuit area is provided with a PWM waveform generating principle circuit on the front side thereof, and the circuit area is provided with a plurality of fault switches electrically connected to the PWM waveform generating principle circuit on the back side thereof, and different fault states of the PWM waveform generating principle circuit can be formed by the on-off combination of the fault switches, and the function control area is provided with a control switch for controlling the fault switches; The cover plate can selectively cover the function control area.

2. The PWM waveform generating circuit detection and application training device according to claim 1, characterized in that: The PWM waveform generation principle circuit includes a direct current generation circuit, a triangle wave generation circuit, and a PWM wave output circuit; The DC power generation circuit is used to generate DC power with adjustable voltage; The triangular wave generating circuit is used to generate a triangular wave with adjustable frequency and amplitude; The PWM wave output circuit is used to compare the direct current and the triangle wave, and output a PWM square wave according to the comparison result.

3. The PWM waveform generating circuit detection and application training device according to claim 2, characterized in that: The fault switch includes an open circuit fault switch and a short circuit fault switch. The open circuit fault switch is used to open the circuit of the corresponding component, and the short circuit fault switch is used to short the circuit of the corresponding component.

4. The PWM waveform generating circuit detection and application training device according to claim 3, characterized in that: The DC power generating circuit includes a voltage-dividing resistor, a variable resistor and a voltage-stabilizing module. The voltage-dividing resistor is connected in series between a predetermined voltage input terminal and a first fixed terminal of the variable resistor, the second fixed terminal is grounded, and the sliding terminal of the variable resistor is connected to a DC power output terminal. The voltage-stabilizing module includes a first electrolytic capacitor and a first ceramic capacitor connected in parallel, and the positive electrode of the first electrolytic capacitor is connected to the first fixed terminal.

5. The PWM waveform generating circuit detection and application training device according to claim 4, characterized in that: The triangle wave generating circuit includes an OP297 operational amplifier having 8 pins, and the pins of the operational amplifier are connected as follows: Pin 8 and pin 4 are connected to the positive and negative poles of the power supply respectively, pin 2 and pin 5 are grounded, pin 1 is divided into a first path and a second path, both of which are connected to the triangular wave output end, the first path includes a first potentiometer and is feedback connected to pin 3, the second path includes a second potentiometer and is feedback connected to pin 6, a filter capacitor is connected to the second path, a fixed terminal of the second potentiometer is connected in series with two voltage regulators and then grounded, pin 7 is connected to the triangular wave output end and is feedback connected to pin 6.

6. The PWM waveform generating circuit detection and application training device according to claim 5, characterized in that: The PWM wave output circuit includes an LM111 comparator having 8 pins, and the pins of the comparator are connected as follows: Pin 1 is grounded, pins 5 and 6 are left vacant, pin 2 receives the DC power output from the DC power output terminal, pin 3 receives the triangular wave output from the triangular wave output terminal, pins 8 and 4 are connected to the positive and negative poles of the power supply respectively, pin 7 is connected to the PWM waveform output terminal, and a pull-up resistor is connected between the triangular wave output terminal and the PWM waveform output terminal.

7. The PWM waveform generating circuit detection and application training device according to claim 6, characterized in that: It also includes two passive filtering circuits, which are respectively used close to the operational amplifier and the comparator.

8. The PWM waveform generating circuit detection and application training device according to claim 7, characterized in that: The circuit breaker fault switch includes a first switch connected between the variable resistor and the DC output terminal, a second switch connected to the adjustable tap of the variable resistor, a third switch connected to the adjustable tap of the first potentiometer, a fourth switch connected to the adjustable tap of the second potentiometer, a fifth switch connected between the positive pole of the power supply voltage and the No. 8 pin of the operational amplifier, a sixth switch connected between the No. 7 pin of the operational amplifier and the triangular wave output terminal, a seventh switch connected between the DC output terminal and the No. 2 pin of the comparator, an eighth switch connected between the triangular wave output terminal and the No. 3 pin of the comparator, a ninth switch connected between the power supply voltage and the No. 8 pin of the comparator, and a tenth switch connected between the No. 7 pin of the comparator and the PWM waveform output terminal; The short-circuit fault switch includes an eleventh switch connected in parallel to both ends of the variable resistor, a twelfth switch connected in parallel to the two fixed ends of the first potentiometer, a thirteenth switch connected between pins 2 and 3 of the operational amplifier, a fourteenth switch connected in parallel to the two fixed ends of the second potentiometer, and a fifteenth switch connected to pins 2 and 3 of the comparator.

Images