For an alternating current circuit with resistance, inductance, capacitance, the voltage across the AC power supply is generally not the same as the current it output. If the parameter or power frequency of the circuit is adjusted, the circuit has a resonant phenomenon. According to the circuit of the resonant phenomenon, it can be divided into series resonance and parallel resonance. 1, in series resonance in the R, L, C series circuit, but satisfy the induction XL equal to the capacitive anti-XC, that is, the output voltage and output current of the power source will have a resonance. Since the series circuit occurs, it is also called a series resonance. In order to more deeply understand the phenomenon of series resonance, set up AC series R, L, and C circuitry in MATLAB / Simulink. Set the AC power amplitude is 220V, the frequency is 50Hz, the resistance is 10 ohms, according to the condition of resonance in series circuit, set L is 0.0318h, C is 3.1831e-04f, and the simulation results shown below. By analyzing the simulation waveform: (1) When the series circuit is resonant, the impedance value in the circuit reaches the minimum. In the case of the power supply voltage, the circuit has occurred in series resonance so that the current in the circuit reaches the maximum value. (2) Due to the voltage of the power supply and its output current, the circuit is resistant to the power supply. The power supplied to the circuit is completely consumed by resistance, and there is no energy exchange between the power supply and the circuit. Energy exchange only occurs between inductor coils and capacitors. (3) Due to the occurrence of series resonance, the sensing resistance is equal to the capacitive resistance, the voltage between the voltage and the voltage between the inductors, etc., the phase is exactly the opposite, mutual offset, and the entire circuit does not work. (4) Adjust the resistance value from 10 ohms to 5 ohms, other conditions are unchanged. At this time, the sensing resistance is equal to the capacitive resistance, the voltage waveform and the voltage waveform between the two ends of the inductor, and the voltage waveform of the capacitor are shown below. As can be seen from the figure, the voltage between the two ends of the inductor is much larger than the power supply voltage, i.e., an overvoltage may cause the coil and the capacitor insulation to break through. Therefore, in the power engineering to avoid serial resonance. 2, in parallel, in the parallel circuit of R, L, C, but satisfy the induction XL equal to the capacitive anti-XC, that is, the output voltage of the power source and the output current of the power source will resonate. Since the parallel circuit occurs, it is also known as parallel resonance. In order to more deeply understand the phenomenon of parallel resonance, the AC in MATLAB / SIMULINK is set in parallel R, L, C circuits. Set the AC power amplitude is 220V, the frequency is 50Hz, the resistance is 10 ohms, according to the condition of resonance in the parallel circuit, set L is 0.0318h, Diangon.comc is 3.1831E-04F, and the simulation results are shown below. By analyzing the simulation waveform: (1) When the circuit occurs in parallel, the modulus of the circuit's impedance reaches the maximum value, thereby reaching the circuit current to the minimum. (2) The power supply voltage and the power supply current are in phase, and the circuit is resistant to the power supply. (3) When parallel resonance, the inductor branch and the capacitor branch current are substantially equal. The characteristics of impedance mode high when the circuit occurred in electrical technologies, is used to select signal or eliminate interference. Responsible Editor: LQ
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