SU741408A1 - Method of automatic tuning inverter frequency - Google Patents

Description

The invention relates to a converter technique, namely, to devices for controlling the frequency of the output voltage of the inverters, and can be used, for example, to auto-tune the frequency of the output voltage of electrothermal units with thyristor inverters. A device for controlling the frequency of an inverter is known, which contains a functional converter, a threshold element, a filter, an amplifier, and a controlled clock generator Vll. The closest to the technical essence of this invention is an automatic frequency control device containing a phase discriminator, a ftr, an amplifier and a controlled clock pulse generator. 23 The disadvantage of such a device is a relatively narrow frequency range in which normal auto-tuning is possible. So, if the change in the frequency of the inverter is large, it is possible to operate the device with an adjustment not of the main frequency, but of its multiple frequency. The purpose of the invention is to expand the frequency range. This goal is achieved by the fact that in the inverter's automatic frequency control device, which contains a two-input logic element, whose first input is the common input of the device, and the output through a filter is connected to the first input of the differential amplifier, the second input of which is an input for | s, the output is connected to the input of a controlled clock pulse generator, the filter is controlled, the output of the clock pulse generator is connected to the second input of the Ni element, moreover, two waiting oscillators, a pulse subtraction element and a relay element are added to it the first waiting generator is connected to the output of the element I, the input of the second to the output of the clock generator, the outputs of both the waiting geeira-

The tori are connected to the corresponding inputs of the pulse subtraction element, the output of which is connected to the control input of the filter through a relay element.

Waiting pulse generators can be executed, in particular, in the form of differentiating chains, a subtraction element on the diodes, and a relay element in the form of a key element with an integrating filter at the input. In FIG. 1 is a functional diagram of an inverter self-tuning device; Fig. 2 shows timing diagrams for the operation of the device; in fig. 3 shows an embodiment of the device. The device operates as follows. Input signal Ue; the inverter load (amplified and limited) is fed to the input of element 1 I, where it is compared with the output signal of the 4 clock pulse generator. The output signal of the element And, proportional to the phase angle, is fed through a filter 2 to the first input of the differential amplifier 3, where it is compared with the reference signal Uon Amplified difference signal and y is fed to the input controlled by the oscillator 4 clock pulses. From the output of the element 1 and from the output, the generator of 4 clock pulses through the corresponding waiting generators 5 and 6 signals are fed to the inputs of the element 7 of the pulse subtraction. The difference frequency signal is fed to a relay element 8 that controls the transmission coefficient of the filter 2. In the operation of the device, it is possible to distinguish two modes — capture mode and normal operation mode. In the first case, the inverter frequency is much lower than the resonance frequency of the load. In this case, the frequency of the current in the load may not coincide with the frequency of the output current of the inverter, but it is multiple to it, t, e, to exceed it by 2–3 or more times. FIG. Figure 2 shows the capture mode for the case when the frequency in the load is twice the frequency of the inverter. The diagrams show the output signal (voltage or load current of the inverter, amplified and limited); Up is the output signal of the clock pulse generator, which determines the frequency of the output current of the inverter; Up is the output signal of the element I — the output pulses of the waiting generator 6, triggered from the generator output 4 clock pulses;, 1), the output pulses of the waiting generator 5, triggered from the output of the element 1 AND; VJpr is the output signal of the pulse subtraction element 7.

Claims (2)

Element 1 And works in such a way that the output signal appears only when there are signals on both inputs. At the same time, the output pulse of the element is And is proportional to the phase angle between the output voltage of the clock generator and the input signal of the inputs, and the frequency of these pulses is determined by the frequency of the input signal of the comparison. The frequencies of both signals U and Up are unified by means of the waiting generators 5 and 6, These generators, when a signal arrives at the output of a pulse with a stable amplitude and duration, and wr, the same pulses are compared in the pulse subtraction element 7. Since liaK in the pulse frequency capture mode at both inputs does not coincide in time for the specified reasons, then differential frequency pulses appear at the output of the subtraction element, which affect the relay element changing the filter transmission coefficient. At the same time, the output signal Ъf of the filter 1 supplied to the input of amplifier 3 begins to change. Since the output signal of amplifier U of the & and С HSA controller for the clock generator is defined as () where V4 is the gain factor of amplifier 3, This also changes the generator frequency accordingly. This frequency change will occur until the output pulse element will have differential pulses, i.e., until the frequency of the input signal becomes equal to the generator frequency. This capture mode ends, but the load is not yet tuned in resonance. The adjustment is carried out in the usual way by means of an AND element indicating the phase angle, the signal of which is compared after filtering with the reference signal. In this case, the frequency of the generator is changed else until the phase angle reaches the desired, for example, phase angle corresponding to the resonance. In the normal mode, there is no signal at the output of the pulse subtraction element and, therefore, the relay element does not affect the filter. On. FIG. 3 shows an example of a specific implementation of the device, where the diodes of the subtraction element (9, 10, 11) are additionally designated, which integrates the filter (12) with the key element (13). The waiting generators 5, 6 can be executed, in particular, in the form of differentiating chains, the subtraction element 7 - on diodes 9, 10, 11, and the relay element 8 - in the form. key element with an integrated input filter. Thus, the proposed device provides a significantly extended frequency range at which normal capture and automatic frequency control are possible. (Claim 1, an inverter self-tuning device containing a two-input logic element AND, the first input of which is the common input of the device, and The code through the filter is connected to the first input of the differential amplifier, the second input of which is the input for the reference signal, and the output is connected to the input of the controlled clock generator, In order to expand the frequency range, the filter is controllable in it, the output of the clock pulse generator is connected to the second input of the AND element, and 74 8 it is additionally introduced two waiting generators, the pulse subtraction element and the relay element the input of the first standby generator is connected to the output of the And element, the input of the second is connected to the output of the clock pulse generator, the outputs of both of the waiting generators are connected to the corresponding inputs of the pulse subtraction element, the output of which is through the relay element Linked to the control input of the filter. 2. A device according to claim 1, characterized in that the clock pulse generator is provided with an additional inverse output associated with the second pulse generator. both of the waiting pulse generators are made in the form of differentiating chains, the pulse subtraction element is made in the form of three diodes, the anode of the first one connected to the output of the first waiting generator, the second cathode to the output of the second generator, the third cathode to the input of the relay element. the remaining electrodes of the diodes are combined, and the relay element is complete in the form of a 1A element with an integrating filter at the input. Information sources, . taken into account during the examination 1. USSR author's certificate No. 573899, кп. H O4 L 7/04, 22.O1.76 2. The patent of Germany No. 2206279, l. H 02 J 3/38, published 03.02.77 Uc % ".Us itz) li-i Uy About Pop. and and, g CR {; Phi1.1