SU432652A1 - METHOD OF MANAGEMENT OF DIRECT VENTILATION CONVERTER - Google Patents

Description

one

Methods are known for controlling direct valve converters of the input T-phase voltage to an alternating voltage of a stable lower frequency, using a master oscillator and a thyristor converter with natural commutation.

According to the proposed method, the control of the thyristors is carried out using pulses switched with the output voltage frequency under the action of single control pulses, which are obtained using a master oscillator of the required output frequency, which forms gating signals that serve to separate the single control pulses that most closely match the period of the master oscillator, from a sequence of pulses, following synchronously with the frequency of the input t-phase voltage.

Such a technical solution makes it possible to improve the shape of the output voltage curve of the converter by reducing the content of low-frequency components in it, including the DC components.

FIG. 1 is a diagram illustrating the proposed control method applied to a three-phase single-phase direct frequency converter; on

FIG. 2 (a, b, c, d, e) are diagrams of the system.

Peak transformers 1-3 connected to each phase of the supply voltage through

the ballasts produce pulses at the moments when the supply voltage passes through the bullets (Fig. 26). These pulses come in a common circuit, which includes a pulse transformer 4 and a semiconductor key element 5, which prohibits or allows the passage of pulses from peak transformers. As a key element, two back-to-back single-conducting keys or one two-conducting key can be used.

The waiting multivibrator 6, assembled according to any of the known schemes, is triggered by pulses coming from transformer 4, and

the output voltage of the multivibrator 6 serves to control the key element 5, and when there is a voltage at the output of the multivibrator, the key element is closed, and when not, it is open. The operation diagram of the multivibrator is presented in FIG. 2 in.

At the same time, the pulse removed from the transformer 4 serves to synchronize the control generator 7, the output voltage of which serves as the reference voltage for the control system 8 with the power section of the frequency converter 9 (Fig. 2d, d). When the first pulse arrives from pictransformers 1-3 into a common circuit 4-5, a pulse transformer generates a pulse arriving at the multivibrator start and synchronization, from the moment it arrives, one half-wave of the control (reference) generator voltage 7 begins to form.

The waiting multivibrator 6 provides a voltage for the required period, determined by the required frequency of the output voltage of the frequency converter 9. This voltage is applied to the input of the key element 5 and closes it. After the end of the output voltage of the multivibrator, the key element opens and the first reverse polarity pulse from transformers 1–3 to circuit 4–5 is fed to synchronization through transformer 4, as a result of which another half-wave of reference voltage begins to form. At the same time, switching of the multivibrator 6 occurs, the output voltage of which closes the key element 5, etc.

Thus, the period of the control voltage of the generator 7 will be a multiple of the number of elementary switching intervals, resulting in the low-frequency components in the output voltage curve of the converter due to the inconsistency of its frequencies

input and output voltages will be completely absent. In order to reduce the maximum error in frequency, a sensing organ 10 is inserted, which changes the duty cycle of the output voltage of the driving multivibrator 6. The diagram also shows the power source 11 with the number of phases t and the filter 12.

Subject invention

A method of controlling a direct gate converter of an input t-phase voltage to an alternating voltage of a stable lower frequency, using a master oscillator and a thyristor converter with natural commutation, characterized in that, in order to improve the shape of the output voltage curve of the converter, the thyristors are controlled by pulses switched with the output voltage frequency under the action of single control pulses, to obtain which use the master oscillator Op desired output frequency forming gating signals which serve to isolate single control pulses closest coinciding with a period of the master oscillator of the pulse sequence in synchronism with the frequency of the following input / n-phase voltage.