CALCULATION OF CURRENT LOADING OF THREE-PHASE BRIDGE RADIATION IN NON-SUPERMEAL MODES UNDER THE FILTRATION AVAILABILITY
The curves of the rectified voltage of the non-ventilated modes of the three-phase bridge rectifier circuit have in their composition a number of non-canonical higher harmonics, which results in significant pulsations of the load current. Hence the problem of choosing the optimal composition of filters in order to prove the load current pulsation coefficient to allowable values. The analysis of the current state of the problem is carried out by studying the latest publications.
The analytical expressions and forms of load current curves are obtained based on the results of mathematical modeling of the resonant and inductive filters higher harmonics influence on the outputs and rectifier loads, respectively, on the leads and in the rectifier load cell. The value of the current ripple coefficient in the load cell for the individual cases of the non-ventilated mode of the three-phase bridge rectifier is calculated. The curves of the currents given in this article are valid for those forms of rectified voltage that arises in non-blunt modes of the three-phase bridge rectifier scheme, and can be obtained under the condition of a known composition of higher harmonics of the output voltage of the rectifier. It is shown that the establishment of a resonance filter at the frequency of the largest harmonic significantly reduces the current pulsation coefficient in the load cell.
In the case of a real resonance filter at the output of the rectifier in the current of the load circuit there will be a harmonic, which will proceed under the action of a voltage drop on the active resistance of the filter. However, its effect will be negligible, since the active resistance of the filters is usually small. The level of harmonic components in the load current will also diminish somewhat as a result of the branching of a certain value of these currents through the branches of the resonant filters.
The proposed method allows to calculate the current in the recirculation load cell in non-ventilated modes, taking into account a certain composition of resonant parallel and inductive serial filters to achieve the desired level of current pulsations.
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