SU985923A1 - Digital device for control of voltage inverter - Google Patents

Description

(54) DIGITAL DEVICE FOR CONTROLLING VOLTAGE INVERTER

The invention relates to electrical engineering, namely to control systems. lazy autonomous voltage inverters, and can be used in variable-frequency AC drives with digital control.

A device for controlling autonomous inverters with pulse-width modulation is known, ensuring synchronization of the carrier and output frequency and periodic switching of the frequency ratio of these frequencies. The device contains a generator, a frequency divider, a generator of the reference and modulating voltages, shapers, a distributor, and a frequency multiplier switch 1.

A disadvantage of this device is the use of analog operations in the generation of control pulses and commands to switch the multiplicity, which leads to a decrease. stability and complexity of the scheme.

It is also known to control a three-phase thyristor frequency converter, which contains an analog converter — a code, a frequency master, drivers, a distributor, a logic circuit, and a frequency multiplier circuit. This device generates output signals on the digital principle. C2.

The disadvantages of the known device are: va are the complexity of the circuit and the formation of commands for switching the frequency multiplicity as a function of the input signal level, as a result of which it maintains the required multiplicity, frequency

10 in the process of frequency control is almost impossible. /

NSShb closer to the proposed technical essence and the achieved result of the digital device

15 to be inserted by the voltage inverter contains a code-frequency converter, two reversible counters with digital oscillators, a clock time generator, a distributor, and

20 switch multiplicity C 31.

One: This device has the complexity of irrational use of the counter. If necessary, the formation of a three-phase

25 of the control pulse system here. Twelve reversible counters will be required, and at the output of the distributor, a complex driver circuit is required. In addition, such a system is formed zak-,

30 whipped circuits, for example, an analog converter-code-input input, a code-frequency converter-converter-code-frequency converter-analogue converter-code converter, and this may result in a clock violation of the entire system and cause malfunctions due to the delay. . The purpose of the invention is to increase the reliability and simplify the voltage inverter control device. This goal is achieved by the fact that a digital device for controlling a voltage inverter is equipped with a logic unit made on an OR element connected through a single AND element to the inputs of three other OR elements, and an output driver made on RS triggers, triggers with a counting input and elements AND, where the converter code output is the frequency through the counter plug to the multiplicity switch, the outputs of the distributor and the outputs of the decoder, except the last one, are connected respectively to the input of one OR element and to the element This AND logical block, the last output of the decoder is connected to one input of ftstriggers, the other inputs of which are connected to the outputs of three elements OR logical block, to the inputs of flip-flops with counting inputs the corresponding outputs of the distributor are connected, the output of each RS-flip-flop is connected to the first inputs of two corresponding elements And, to the second inputs of which are connected the outputs of the corresponding trigger with the counting input. Hal in the drawing is a schematic of the device. The device contains a clock frequency generator 1 connected to an controlled frequency divider 2, components of frequency converter 3, code frequency, counter 4, linear decoder 5, quasi-sinusoidal voltage driver, multiplicity switch 7, distributor 8, logic unit 9, shaper 10, elements OR 11, elements AND 12f elements OR 13, triggers 14, triggers with counting input 15 and elements AND 16. The device works as follows. The pulses from the output of the 1 clock frequency generator arrive at the counting input of the 2 pulse counter, the parallel inputs of which each time it overflow records the inverted code of the required frequency (Thus, a simple circuit of the controlled frequency divider c combined with the clock frequency generator functions of the converter code-3 frequency.The signal from the output of the converter frequency code is fed to the input of counter 4 which, together with the linear decoder 5, forms the circuit of the former 6 Each time the counter overflows, the signals from its output are fed to the input of the digital switch 7, made on the counter, which forms the control controlled by the {d, oty ,,,., df,) divider, and the change in the division factor is the same code as frequency reference. The multiplicity switch generates the signals for switching the positions of the distributor 8 with a multiplicity proportional to the input frequency set by the code. All twelve distributor outputs go to logic block 9, where the decoder outputs are connected. Next, the pulses from the logical block are fed to the inputs of the generator 10, at the inputs of which a three-phase system of pulses U- (- Ug, modulated according to a sinusoidal law and entering the output stages to control the inverter valves) is produced. The outputs of the distributor through the elements of OR 11 are fed to the inputs of the elements And 12, to the other inputs of which are connected the outputs of the decoder. As a result, the selection of signals from the output of the decoder 5 is carried out by pulses of the distributor. The circuit diagram is given for the case of approximation of the field the fault of the sinusoidal output voltage period is twelve intervals (steps. For this case, 1, 3, 7, 13, 20, 28 outputs of the linear distributor are used with the counter 32 capacity. And the rising half-wave is formed by selecting the output signals of the decoder in the forward direction, and falling part of the half-wave is sampled in the opposite direction. Signals from the outputs of three groups of elements AND logical block, combined through the elements OR 13, are fed to the inputs of the RS-flip-flops 14 of the driver 10, the other inputs of these flip-flops are given a signal from 3 1 output decoder. Simultaneously, from the zero, fourth and tenth outputs of the distributor, pulses are fed to the counting inputs of the trigger 16 of the driver. The formation of impulses modulated by sinusoidal modulation and their addressing by the working valves of the inverter is controlled by There are elements And 16 shaper. Thus, on the same counter with the decoder, the modulation of the control voltages of all the inverter valves is sinusoidally formed, the time selection of these voltages is performed by the logic block from the distributor signals, and

Claims (1)

Claim A digital device for controlling a voltage inverter containing a code-frequency converter, a counter with a decoder at the output, and a frequency switch connected to the input of the distributor, characterized in that, in order to increase reliability and simplification, it is equipped with a logic unit made on an OR element connected through one AND element to the inputs of three other OR elements, and the output. a shaper made on RS triggers, triggers with a counting input and AND elements, and the output of the code-frequency converter through a counter is connected to the switch. multiplicity, the output of the distributor and the output of the decoder ^ except the last, are connected respectively to the input 5 of one OR element and to the input of the AND element of the logical unit, the last decoder output is connected to one input of the RC flip-flops, the other inputs of which are connected to the outputs of three other 10 OR elements of the logical ^ block, the corresponding outputs of the distributor are connected to the inputs of the triggers with counting inputs, the output each I RS-trigger is connected to the first. 15 I will give two corresponding AND elements, to the second inputs of which the outputs of the corresponding trigger with a counting input are connected.