Article number Wu Zhonghua Chaoyang Vocational University. Chaoyangcheng. The phase shift control pulse is composed of power amplification and other parts. And there are perfect protection measures. The required peripheral components are few and the scope of application is wide. It is an integrated trigger with high performance-price ratio.
It can be seen from the working principle and structure of Gong 1ding 785 that 785 is composed of voltage distribution synchronous zero-crossing detection discharge monitoring synchronous register control comparison pulse formation and pressure distribution.
Pin 16 and pin 1 are the DC power input terminal and the grounding male terminal, respectively. Terminal 5 is the input terminal of the synchronization signal. The synchronization signal is sent to the synchronous registered tooth wave signal generator through the synchronous zero-crossing circuit. At the zero-crossing moment of the sinusoidal signal, the wave generator quickly discharges and starts to charge from the initial value of 0. Change 10 The external capacitance of the foot or the external resistance of foot 9 can change the slope of the moment tooth wave. The torque wave voltage is compared with the control voltage of the foot. When the torque wave voltage reaches the amplitude, a pulse is generated, and the control signal is generated and sent to the pulse formation and distribution link. From this, it can be seen that the magnitude of the control angle is determined by the amplitude value of the control voltage Decide. Pin 14 and pin 15 are pulse output terminals corresponding to positive and negative half cycles respectively. Pin 4 and pin 2 are the inverting pulse output terminals of pin 14 and pin 15, respectively, which can be flexibly selected according to actual needs. The generated pulse width is determined by the external capacitance values ​​of pin 12 and pin 13, respectively, pin 3 and pin 7 are the pulse synthesis output terminals, and are flipped twice every power cycle. Pin 6 is the pulse blocking terminal, which is controlled by the level of pin 6. When 1, the blockade is lifted. When =, the blockade is valid. It is a control terminal set up for the system to overcurrent or overvoltage or perform other control. The waveform of each foot of the Ugren 785 2. The main technical indicators are as follows. The peak value of the synchronous voltage 2 should be less than the pulse formation and division of the DC working power supply, and the output Tuner 450 pulse equalization degree 1.5.
Pulse front, suitable for the typical application of thyristor rectifier circuit and AC voltage regulation circuit 2 D 04785 The following introduces the actual circuit of DC motor speed regulation powered by seed thyristor. The circuit takes 1 to 785 as the core. It adopts closed loop control of speed feedback and has over-current and over-voltage protection functions.
2.1 Main circuit and exciting color circuit 3, adopts the form of single-phase half-controlled bridge, in order to ensure the current connection and smooth series connection of smoothing reactor and relay diode, 3. To speed up braking and stop, use energy consumption Braking, powered by the resistance hole 2 and the excitation of the contactor tender motor. The power is supplied by a separate rectifier circuit. In order to prevent the motor from demagnetization and causing a flying accident, an undercurrent relay is connected in series in the excitation circuit. Make adjustments.
2.2 Control power supply and synchronous signal control circuit 4 Synchronous transformer 7 After the system is powered on and exchanged for 22 teams, Fubian provides two sets of independent AC voltages 71 and 72.71 through the transistor, 12 half-wave rectification and after 7815 voltage stabilization is provided to the system + Working voltage, provide synchronous signal to 10785 after resistance and 4 and 5 partial pressure. After rectification and filtering, it can be directly used as the trigger pulse power supply of the thyristor.
Overvoltage signal Overcurrent signal 2.3 Voltage control and touch, the link voltage control uses the operational amplifier as the core voltage, the output of the given potentiometer and the speed feedback voltage are superimposed in parallel, and the pin voltage of 1085 is controlled after amplification, that is, the trigger pulse angle is controlled. size. When the load increases, the speed decreases. The feedback power 8 detected by the tachogenerator decreases. Therefore, the pin 1 of 785 decreases accordingly. Trigger the phase solution, lt; move forward, the voltage at both ends of the armature increases, which counteracts the speed drop and makes the system have a certain mechanical hardness.
The minimum phase angle potentiometer in the system takes 2 and the pole, 3 control, when the output voltage of the op amp is less than the partial voltage of 2, the pole, 13 is turned on, at this time the pin voltage of a few 785 is the minimum control angle, corresponding The voltage. The maximum angle, the control voltage is determined by the regulator tube milk 2, and the potentiometer evaluation 4.
The trigger link is composed of a photoelectric coupler trigger pulse power supply and the normally closed contact of relay 1 etc. Under the action of a synchronous signal, according to the output voltage of the op amp, the output control angle from pin 7 of Han 785 is negative, and the interval is 18 The pulse and the width of the thrust are determined by the external capacitance of pins 12 and 13. The negative pulse drives the galvanic coupler, so that the positive pulse with the same wide skin is applied between the gate cathodes of the thyristors, making it conductive in the respective positive and negative half cycles.
2.4 Protection link The function of the protection link is to block the trigger pulse to stop the load when the output voltage or current is overloaded. This link takes the pole tube 3 as the core. When the load terminal is over-voltage or over-current, the signal detected by the current and voltage sensor makes the corresponding voltage stabilizing pole tube, 17, 19 breakdown, the pole tube 13 is saturated and turned on, and the redundant 785 6 The pin is low level 0, the output pulse is blocked, and at the same time, the relay 1 is energized, and the normally open contact pulls in and locks the relay. In addition, the normally closed contact connected in series in the trigger circuit is disconnected, cutting off the trigger source. Make protection more reliable. 3 Troubleshooting. Manually press the reset switch 513.
The relay husband calls this, the 6 pins of 785 are high power, 1. The block letter 4 is lifted. System 1 is newly put into operation.
1 Huang Jun Semiconductor converter technology editor Shao Baoshan, Beijing Machinery Industry Press, took up 67 pages of curiosity, which can gradually open the door to imagination, thereby developing students' ability to create imagination.
2.4 It is necessary to guide students to think in an indirect reflection of objective quotient on the summary of objective reality. The high-level form of the human brain reflecting objective reality. Mr. Tao said that if he does not use his brain, he will be knocked down sooner or later. This shows the importance of thinking.
2.4.1 In the teaching of weaving, teachers should not control too much and control too much. Teachers should give students free time to think according to the teaching content. In thinking, they not only develop the initiative and subjectivity of students but also raise questions they found. And solve the problem environment.
2.4.2 Using Heuristic Teaching Method in Teaching Method Confucius in China has no indignation, no stern words, and later Socrates uses the question and answer method to inspire students to think independently; Czech Comenius accuses infusion teaching It is to force students to use other people's eyes to use other people's brains to make themselves smart. As a result, most people have no knowledge. The distinctive feature of the heuristic teaching thought of modern teaching theory is that it is student-centered.
The teacher put in the full house. Intensive talk. The students have learned to test first and then talked about 2 tests. 7 This is mainly based on the study of cattle freedom 73. 2.4.3 It may be possible to make seeds for students to ask. Zankov said that he taught students to think, which is the most important thing for students Valuable capital. This shows the importance of thinking. In the theory teaching of physical education majors in normal universities, the theoretical knowledge is combined with the actual practice of physical education, students gradually change from passive thinking to active thinking, in order to improve thinking skills, so as to cultivate students' innovative ability.
2.4.4 Reforming the life style of traditional examinations in performance assessment The traditional examinations are mostly about knowledge and life. Close the paper and complete the answer within two hours. This form of memory nine is a stifling of their creativity. Therefore, to cultivate students' innovative ability nine must reform this examination method, take open-book examinations, and ask why. Teachers' judgment on this type of answer depends on whether their arguments are reasonable and reasonable, and it is not necessary to easily determine whether they are right or wrong.
3 Conclusion Innovation is the hope of a country and a nation. The school's ability to cultivate students' innovation is related to the successor innovative talents required by the national innovation project. Cultivating students' innovative abilities in the teaching of theoretical courses for physical education majors in normal colleges, and changing the cloning education model is a hot spot of physical education reform before 1st and the need for comprehensive quality in the 21st century.
1 Liu Zeyu. Discuss Deng Xiaoping's innovative spirit and its practical significance. Wen Wei Po, 1998.
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