Khanahmedova S., Safiyev R., Guluzade E.
PRINCIPLE OF OPERATION OF FREQUENCY CONVERTERS USING A NATURAL SWITCHING PROCESS *
Аннотация:
the article discusses some issues related to thyristor frequency converters using a natural switching process, i.e. closed by the reverse voltage of the network. It is taken into account that multiphase frequency converters have higher technical and economic indicators
Ключевые слова:
thyristor, frequency converter, reverse voltage, multiphase frequency converter, network, sine waveform
DOI 10.24412/2712-8849-2023-966-324-327
УДК 621.8
Khanahmedova S.
Azerbaijan State Oil and Industry University
(Baku, Azerbaijan)
Safiyev R.
Azerbaijan State Oil and Industry University
(Baku, Azerbaijan)
Guluzade E.
Azerbaijan State Oil and Industry University
(Baku, Azerbaijan)
PRINCIPLE OF OPERATION OF FREQUENCY
CONVERTERS USING A NATURAL SWITCHING PROCESS
Abstract: the article discusses some issues related to thyristor frequency converters using a natural switching process, i.e. closed by the reverse voltage of the network. It is taken into account that multiphase frequency converters have higher technical and economic indicators.
Keywords: thyristor, frequency converter, reverse voltage, multiphase frequency converter, network, sine waveform.
Introduction. In the frequency converters, thyristors are connected through a natural switching process. Therefore, the output frequency of such speed transducers is less than the bandwidth. These frequency converters are widely used to control the speed of asynchronous electric drives in a low frequency range. The number of input and output phases of the frequency converters three-phase/single-phase FCCN determines its structure and scheme of the frequency converter as its main classification indicator. It should be noted that multiphase frequency converters have higher technical and economic indicators [1].
Principle of operation of the frequency converters three-phase/single-phase - FCCN (Fig. 1). The impulses that open the thyristors are synchronized to the cathode group thyristors (T1,T2,T3) synchronously with network frequency. This group works in the tractor regulator mode and creates a positive halfwave due to the Zy load zero point of the transistor. The control pulses control the value of the output voltage by providing a sliding angle to the opening angle for the line voltage. When the control pulses of the Anode group thyristors (T4,T5,T6) are given, the Zy charge generates negative zero points due to the zero point of the transformer. Anode and cathodic group thyristor turns into a variable voltage in the load f2<f1. The frequency of f2 is determined by the duration of the output of each group of thyristors [1, 2].
In the three-phase / single-phase scheme, the thyristors of each group switch between p/3 interval. It can be written for frequency converter frequency without taking into account the switching interval,
(2n+1);
here n - is the number of sine waveform; - the angle up to the zero fall of the half-back. The thyristors are divided into two groups - anode group (T4,T5,T6) and cathode groups (T1,T2,T3). Let's assume that Zy load is an active character. Control impulse is given by cathode (T1,T2,T3 ) and anode (T2,T4,T6) groups [2].
Fig. 1. Scheme of the three-phase / single-phase FCCN
In general, the dependence of the frequency converter on the input and output frequencies can be summarized as follows:
f2=, (1)
here m1 - is the number of phases of the network; f1 and f2 are input and output speeds of the frequency converter accurrentingly. From (1) shows that, as the values n change, the frequency f2 will change discrete. It is necessary to create a break (φ) between the tristor groups and the tristor groups that work to speed the output speed. In this case, the dependence between the input and output frequencies of the frequency converter is expressed as follows [2]:
f2 = ; (2)
for m1=3; f1=50 Hz; n=1 the dependence of f2 on φ.
f2 = , (3)
In fig. 2 shows is a smoothly change frequency f2 depending on φ. When the voltage in the active-inductive load passes through the zero, the load current does not go from zero because the load in the load lags behind the voltage. In this case, in the invertor mode, the appropriate tymitter group for the flow of load to the network (induced energy return to the network - for recuperation) is transmitted to the network.
Direct-to-turn frequency converter (FCCN) differs from the frequency converter, which is the intermediate constant current converter, with the small size and weight of the FCCN. The FCCNs are used only at low frequencies (30¸50)Hz, influencing them as a source of voltage. Therefore, the power of the FCCN is smaller than the power of the electric motor it operates.
Fig. 2. Smoothly change of the frequency f2 depends on φ
REFERENCES:
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Ссылка для цитирования:
Khanahmedova S., Safiyev R., Guluzade E. PRINCIPLE OF OPERATION OF FREQUENCY CONVERTERS USING A NATURAL SWITCHING PROCESS // Вестник науки №9 (66) том 4. С. 324 - 327. 2023 г. ISSN 2712-8849 // Электронный ресурс: https://www.вестник-науки.рф/article/10074 (дата обращения: 17.05.2024 г.)
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