Passive inverter output filter with series resonance branch circuit
An output filter and series resonance technology, which is applied in the field of passive inverter output filter, can solve the problems of high filter cost and high switching frequency.
Inactive Publication Date: 2013-10-02
HEFEI UNIV OF TECH
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Problems solved by technology
[0003] Traditional passive inverter output filters mainly use LC filters to filter out the PWM (pulse width modulation) switching frequency and its integer multiple frequency harmonics generated by the passive filter. However, it is affected by switching devices and losses. Limitation, the switching frequency cannot be made very high. In order to effectively filter out the harmonics with the switching frequency as the main component, an LC filter with a lower cut-off frequency must be used, resulting in a higher cost of the filter
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[0018] figure 1 It is the circuit schematic diagram of the first embodiment of the present invention. It can be seen from the figure that the passive inverter uses PWM (pulse width modulation) to generate the voltage of the frequency and amplitude required by the load, and transmits the electric energy to the load through the LC filter composed of the inductor L and the capacitor C; in addition, Inductance L f and capacitance C f A series resonant branch is formed and connected in parallel with capacitor C. Its series resonant frequency is the same or similar to the switching frequency of the passive inverter, thus providing a bypass channel for the switching frequency harmonics of the passive inverter. The LC filter composed of the above inductance L and capacitance C and the inductance L f , capacitance C f The composed series resonant branches together constitute the passive inverter output filter with series resonant branches proposed by the present invention.
[0019...
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The invention discloses a passive inverter output filter with a series resonance branch circuit, which includes a conventional LC output filter, and a series resonance branch circuit formed by connecting an inductor and a capacitor in series, wherein the resonance frequency of the series resonance branch circuit is equal to or close to the switching frequency of a passive inverter. The series resonance branch circuit can filter main components in output harmonic waves of the passive inverter, so that the overall cost of the filter can be reduced. In addition, the series resonance branch circuit of the filter can be connected with a resistor Rf, so that the series resonance branch circuit has a certain Q value, and thus the situation that the filter performance decreases sharply due to deviation of the resonance frequency can be efficiently avoided.
Description
technical field [0001] The invention relates to a passive inverter, in particular to a passive inverter output filter with a series resonant branch. Background technique [0002] With the development of society and economy, people's demand for passive inverter represented by UPS (uninterruptible power supply) is increasing, and the application of passive inverter is becoming more and more extensive. [0003] Traditional passive inverter output filters mainly use LC filters to filter out the PWM (pulse width modulation) switching frequency and its integer multiple frequency harmonics generated by the passive filter. However, it is affected by switching devices and losses. Due to the limitation, the switching frequency cannot be made very high. In order to effectively filter out the harmonics with the switching frequency as the main component, an LC filter with a lower cut-off frequency must be used, resulting in a higher cost of the filter. Therefore, how to reduce the cost ...
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Inventor 张兴李飞朱虹刘淳刘芳余畅舟
Owner HEFEI UNIV OF TECH