Series parallel resonant external power supply, impedance transformation

It's been confusing us for a long time. Parallel resonance

Originally we or very simple thought, the parallel power drive is uses the overlap time, in order to prevent the short-circuit natural should use the reactor filter, in turn said also may, because is uses the reactor filter but only uses the overlap area the drive. Series circuits are the opposite. But more often than not, the reality is not what we think. Compared with the series resonant circuit and the parallel resonant circuit, the characteristic impedance is certain (that is, the value of L and C must be). The lower the resistance of the series resonant circuit, the higher the quality factor, the higher the value of the parallel resonant circuit resistance, the better the quality factor. Therefore, in order to obtain a high Q value, the general requirements of series. The value of resistance in resonant circuit is very small, and the value of parallel resistor in parallel resonant circuit is higher. When the internal resistance of the signal source cannot be neglected, the internal resistance of the signal source is compared with the ideal excitation source: Increasing the equivalent resistance of the series resonant circuit and reducing the parallel equivalent resistance in the parallel resonant circuit. The consequence is to reduce the quality factor of the resonant circuit. In order to make the Q value of the resonant circuit not affected by the signal source resistance excessively, the resonant impedance of the series resonant circuit is only suitable to work with the low internal resistance signal source, and the resonant impedance of the parallel resonant circuit is suitable to work with high internal resistance signal source. The above is a good explanation for the series resonance at no-load when the Q value is the highest, and the parallel resonance at full load when the Q value is the highest. So our tandem machine is not afraid of full load, the heavier it works, the more secure it is. This is the theory of weak electricity, used in the industrial induction heating industry is still correct. Popular is that the series resonant circuit uses voltage source power supply, parallel resonant circuit using current source power supply, that is, voltage source type induction heating power must match series resonant load circuit, current source type induction heating power must match the parallel resonant load circuit, which is the first matching measure of power and load. Series resonant circuit load matching scheme: From the state of the resonant time to analyze: series resonant circuit in the resonant state of the equivalent impedance of pure resistance, and to achieve the minimum value, the parallel resonant circuit in the resonant state equivalent impedance reached the maximum, in order to obtain the maximum power output power, series resonant circuit using voltage source power supply, parallel resonant circuit using current source power supply. Based on power analysis: a low internal resistance, voltage source, so that its output power to reach the maximum, the highest power utilization, the lower the load impedance of the natural output power greater. Conversely, a high internal resistance, current source, so that its output power reaches the maximum, the load impedance is higher output power. The logic is that the voltage source voltage is constant, The current changes with the load impedance, the current source is constant, and the voltage changes with the load. The conclusion is that the selection of this filter circuit is the initial load matching, in order to make it output the maximum power.