By hvhipot 
AC series resonance? HV Hipot Electric Co., Ltd. specializes in producing AC series resonators, with a wide range of product options. When looking for AC series resonators, choose HV Hipot Electric Co., Ltd..
Today, we will discuss the principle of series resonance with you, analyze some characteristics of the series resonance phenomenon, explore some basic rules of the series resonance phenomenon, so that we can use series resonance power products more freely in applications and analyze some phenomena that occur during the experimental process. The generation of series resonance:
Resonance is a special phenomenon that occurs in a circuit composed of R, L, and C components under certain conditions. Firstly, let’s analyze the conditions under which resonance occurs in a series circuit of R, L, and C, as well as the characteristics of the circuit during resonance. The series circuit of R, L, and C shown in Figure 1, under the action of a sine voltage U, has a complex impedance of:
In the equation, the reactance X=Xl-Xc is a function of the angular frequency ω, and the variation of X with ω is shown in Figure 2. When ω changes from zero to ∞, X changes from – ∞ to+∞. When ω<ω o X＜0， The circuit is capacitive; When ω>ω o, X＞0， The circuit is inductive; When ω=ω o
At this point, the circuit impedance Z (ω o)=R is pure resistance. Voltage and current are in phase, and we call the working state of the circuit at this time resonance. Due to this resonance occurring in a series circuit of R, L, and C, it is also known as series resonance. Equation 1 is the condition for resonance to occur in a series circuit. From this equation, the resonant angular frequency ω o can be obtained as follows:
The resonant frequency is
From this, it can be inferred that the resonant frequency of a series circuit is determined by its own parameters L and C. It is independent of external conditions and is therefore also known as the natural frequency of the circuit. When the power frequency is constant, the circuit parameters L or C can be adjusted to make the natural frequency of the circuit consistent with the power frequency and resonate; When the circuit parameters are constant, resonance can occur by changing the power frequency to match the natural frequency of the circuit.
Characteristics of series resonant power supply in power system applications:
1. The required power capacity is greatly reduced. Series resonant power supply generates high voltage and high current through resonance between resonant reactor and the tested capacitor. In the entire system, the power supply only needs to provide the active consumption part of the system. Therefore, the required power supply for the experiment is only 1/Q of the test capacity.
2. The weight and volume of the equipment have been greatly reduced. In a series resonant power supply, not only is the bulky high-power voltage regulating device and ordinary high-power power frequency test transformer eliminated, but the resonant excitation power supply only requires 1/Q of the test capacity, greatly reducing the weight and volume of the system, usually 1/3-1/5 of ordinary test devices.
3. Improve the waveform of the output voltage. A resonant power supply is a resonant filtering circuit that can improve the waveform distortion of the output voltage, obtain a good sine waveform, and effectively prevent the accidental breakdown of the test sample by harmonic peaks.
4. Prevent large short-circuit currents from burning the fault point. In the series resonance state, when the weak point of the insulation of the test sample is broken down, the circuit immediately disengages and the loop current rapidly drops to 1/Q of the normal test current. However, when conducting voltage withstand tests in parallel resonance or test transformer mode, the breakdown current immediately increases by several tens of times. Compared with the two, the short-circuit current is hundreds of times different from the breakdown current. So, series resonance can effectively identify insulation weaknesses without the concern of large short-circuit currents burning the fault point.
5. There will be no overvoltage recovery. When the test sample breaks down, due to the loss of resonance conditions, the high voltage immediately disappears, the arc immediately extinguishes, and the process of re establishing the recovery voltage is long. It is easy to disconnect the power supply before reaching the flashover voltage again. This voltage recovery process is an intermittent oscillation process of energy accumulation, which is long and does not result in any recovery overvoltage.
The AC series resonant device is a new generation resonant boost device designed by HV Hipot Electric Co., Ltd. based on years of research and development, production, and testing of power frequency resonant boost devices. Variable frequency resonance test is a new high-voltage testing method that uses a reactor and the capacitance of the test object to achieve series resonance and obtain high voltage and current on the test object. It is a new method and trend in high-voltage testing and has been widely used abroad. The frequency conversion resonance test is suitable for high-capacity and high-voltage capacitor specimens, such as generators, large transformers, GIS, and high-voltage cross-linked power cables. It is an on-site testing device used for handover and preventive testing.