SU1356158A1 - Method of controlling three-phase bridge inverter - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to converter equipment, and can be used in the construction of converter systems — an asynchronous motor with autonomous voltage inverters adjustable according to the principle of pulse-width modulation. The purpose of the invention is to improve the voltage form and current at the output of the inverter, to improve the energy performance of the inverter, and to simplify. In this method, on the interval of 0-240 electragrad of the period of the output frequency, sequences of valve control pulses of each phase are formed. A pulse train consists of modulated and. "Modulated regions. 5 il. i (Л С оо СП О) О1 00

Description

The invention relates to electrical engineering, in particular, to converter equipment, and can be used in building frequency converter systems - an asynchronous motor in which the frequency converter is made according to the structure of an unmanaged rectifier - filter - a three-phase bridge inverter, adjustable in frequency and voltage rotary pulse modulation (PWM).

The purpose of the invention is to improve the forms of voltage and current at the output of the inverter, to improve the energy performance of the inverter, and to simplify.

Figure 1 shows the diagrams explaining the proposed method; Fig. 2 is a diagram of a control device for a three-phase bridge with an inverter for implementing the proposed method; Fig. 3 shows the distributor and switch diagrams (for the switch, the diagram for one control channel is shown); Fig. 4 shows diagrams of a control pulse generator, a control unit for adjusting the initial phase of the control pulses and current zero sensors for one phase of the inverter; on fig.Z - diagram of the inverter.

Inverter (fig.Z) contains valves

.1 and 2 phases A, valves 3 and 4 phases B, valves 3 and 6 of phase C, a reverse current bridge on diodes 7-12, source, 13 inverter power supplies. Three-phase active-inductive load 14 - 16, respectively, of phases A, B, C, connected to a star are connected to the output terminals of the inverter.

Fig. 1 denotes: 17 and 18, the modulation law for the first and second modulated sequences 19 and 20, respectively; 21-26 - a pole of unregulated impulses of duration 60 al.grad shifted from one another by 60 el. hail; 27 and 28 are switch output signals for generating pulse control pulses 1. and 2 inverters; 29 and 30 —former output signals (valve control pulses 1 and 2) for the load angle 43 el. Degrees; 31 and 32 — similar signals for the load angle 73 el. Degrees; 33 - linear voltage line AB of the inverter; 34-40 - time points on the interval 0-60 el.grad, corresponding to the switching of at least one inverter valve; 41 - 45 points in time

respectively, for 120,180,240,300, 360 el.grad period of the output linear voltage.

The three-phase bridge inverter control unit (FIG. 2) includes a pulse generator 46, a counter 47, a decoder 48, a distributor 49, a switch 50, a driver pulse for control pulse 51, a control pulse initial phase control unit 52, a current zero sensor 53, a phase splitter 54 pulse generator, the counter and the decoder are connected by

5 therefore, the inputs of the switch 50 are connected to the outputs 55 of the decoder and the outputs 56 of the distributor, the phase splitter 54 is connected by the input 57 to the output of the high-order counter

0 47 5 and the outputs to the inputs 58 of the distributor 49 and the inputs 59 of the block 52 for adjusting the initial phase, the other inputs 60-62 of which are connected to three sensors 33 current zero, respectively

5 phases, and the outputs 63 of the control unit 52 are connected to the first inputs of the pulse driver 31, the second inputs of which are connected to the outputs 64 of the switch 50, and the outputs 63 to 70 of the driver 51 are the device outputs.

The distributor 49 (FIG. 3) contains the elements AND 71.1 -.71.6, the elements SH-72.1-72.6, the inputs 73-78. The elements AND 71.1- 71.6 are the inputs of the distributor, and the outputs 21-26 the elements OR 72.1 - 72.6 - by the distributor outputs,

Switch 30 (FIG. 3 shows

The Q scheme of one control channel, the remaining five channels are performed similarly) contains elements AND 79.1 - 79.3, whose inputs are switch inputs, elements OR 80.1 5 80.4, element OR 81, input 27 of element 80.4 is the output of switch Input 82 is one of the switch inputs.

The sensors 33 zero current contain (figure 4) comparator 83, the input of which

0 is the sensor input, and the output 60 of the comparator 83 is the current zero sensor current.

55

The initial phase control unit 32 contains (FIG. 4) AND 84.1 - 84.2 elements whose inputs are the control unit inputs, outputs 85 and 86 of the elements, RS-triggers 87.1 - 87.2 with outputs 88 and 89, which are the outputs of control unit 2.

The control pulse generator 51 contains (FIG. 4) AND elements 90.1 and 90.2, whose inputs are the driver inputs, and OR elements 91.1-191.2, whose outputs 65 and 66 are the generator outputs.

For phases B and C, the execution of the current zero sensors 53, the initial phase control unit 52 and the control pulse generator 51 is analogous to

In the proposed control method, two modulated sequences of 19,20 are formed (Fig. 1 with a repetition period of 60 al-degrees), in the first 19 of which the modulation law 17 corresponds to the value of the sinusoidal function in the interval O - 60 el, degrees, in the second 20 of which the modulation law 18 corresponds to the value of a sinusoidal function in the interval 60–120 el, hail, six unregulated pulses are formed 21–26 in duration 60 el, hail shifted from each other by 60 el, hail, are formed in the interval O - 240 el , hail, sequence of 27 control pulses neither by the valve of each phase during the period of the output frequency, using four of the six unregulated pulses, with the first 19 modulated pulse sequence being used in the first interval O - 60, the unregulated pulse duration in the second interval 60-120 al. 60 zl.grad, on the third interval 120 - 180 el, degrees - the second 20 modulated pulse sequence, on the fourth interval 180 - 240 z.grad - inverse modulation of the first modulated pulse sequence, while the modulation of the They are applied by moving the leading edge of the pulse, and a sequence of control pulses is generated for each inverter gate, starting with the transition time of the corresponding zero phase current,

The device works as follows.

The pulse generator 46 (FIG. 2) generates at the output a sequence of pulses of a given frequency, a multiple of the voltage frequency at the output of the inverter, and triggers a counter 47 with these pulses, the pulses from the higher bit of which are used as clock pulses and are controlled by a phase splitter 54. 48, codes of numbers defining the durations of the modulated pulses are read out, and at the outputs of the RS flip-flops 87.1 - 87.2, pulse sequences 19, 20 are formed, modulated sinusoidally in sections O respectively - 60 el, hail, and 60 - 120 el. grades; and coming from the outputs 55 of the decoder to the switch 50, From the output of the phase distributor 54 (FIG. 2), the direct pulses and inverse ones go to the input 58 of the distributor 49 and the input 59 of the initial phase control unit 52 — control pulses (FIG. 4). At the output 56 of the distributor 49, unregulated t-pulses 21-26 (fig. 2) with a duration of 60 el are formed, the degrees shifted from one another to 60 el, degrees. For example, the formation of pulses 21 is carried out as follows. Pulses 73 and 74 are received at the inputs of the AND 71.1 element (FIG. 3). At the output of the AND 71.1 element, a Zero signal with a duration of 60 e, hail, interval 34-40 (figure 1) is generated, which enters the inverter element 72.1. (fig. 3), from the output of which the signal 21 is removed (fig. 3 and 1), the formation of pulses 22-26 is carried out similarly to the elements 71.2 71.6, 72.2- 72.6 (fig.3), from the output 56 the distributor 49 (FIG. 2) pulses 21 to 26 (FIG. 1) arrive at one input of the switch 50 (FIG. 4), while the other signals of the decoder 48 arrive at the other inputs of the switch 50. Consider the formation of an imp sov 27 (Figure 1) used for controlling a valve phase inverter 1 A (Figure 5). Signals 21, 23, 24 from the distributor 49, respectively, come to one input of the elements 79.1 of the switch 5Q (FIG. 3), and signals 19, 20, 82 (FIG. 3) from the other inputs of the same elements arrive respectively. decoder 48 (FIG. 2). Pulse sequence 82 is inverse with respect to pulse sequence 19. At the outputs of elements 80.1 - 80.3 (FIG. 3) of inverters, modulated sequences 19, 20.82 are formed, corresponding to 60 e, hail intervals 34 - 40, 41 - 42,

42 - 43 (FIG. 1), which are fed to the inputs of the elements OR 81 (FIG. 3), the fourth input of which is simultaneously. Sequence 22 (Figs. 1 and 3) is received continuously. At the output of element 5 OR 80.4 a pulse sequence 27 is formed (Fig. 1). The formation of the sequence 28 used to control the valve 2 of the phase A of the inverter (Fig. 1), and the sequences used to control the valves of the inverter 3-6, is carried out similarly to the switch (Fig. 4); outputs 64 to the inputs of the driver 5

51 control pulses. The other inputs of the imaging unit 51 receive signals from the code 63 of the initial phase control unit 52, to the inputs of which signals 60-62 20 are supplied (Fig. 2) from the current zeroors 53 and signals 59 s. phase splitter. Consider the formation of control pulses 65 and 66 (Figures 2 and 4) by inverter valves 1 and 2 (Fig.5). From the current zero sensor 53 (FIGS. 2 and 4), the signal 60 is supplied to elements And 84.1, 84.2 (FIG. 4), to the other inputs of which signals are respectively transmitted from the phase splitter 54 (FIG. 2). The output 30 signals 85 and 86 (FIG. 4) of the elements And go to the R-inputs of the RS-flip-flops 87.1 and 87.2 (FIG. 4), the S-inputs of which receive the signals of the phase splitters 54 (FIG. 2). As a result, signals are generated at the output 35 of the control unit 52 with an initial phase corresponding to the transition of the current A of the phase through zero. Signals 88 and 89 (Fig. 4) are applied to the same inputs of the And 40 elements.

90.1 and 90.2 (FIG. 4) of the former 51 (FIG. 2), signals 27 and 28 (FIG. 1) .C of the switch 50 (FIG. 2) are sent to the other inputs of the elements And. Inverted with schemes 91.1 and 45

91.2 (FIG. 4), the signals 65 and 66 are output signals of the device. Figure 4 shows the same output signals 29 - 32 devices for different. personal load angles, with the signals 50 and 30 being formed for a shift factor of cos 1, 0.707 (if

 45 zl.grad), and the signals 31 and 32 form forms - for the coefficient of phase shift cos t 0,259 (H 75 el. Deg).

Claims (1)

Invention Formula The method of controlling a three-phase bridge inverter on fully controlled valves, consisting in that they set a signal with a frequency equal to the output frequency of the inverter, form two modulated pulse sequences, determine the moments of transition of the current value of each phase through zero, characterized in that improving the shape of the voltage and current at the output of the inverter, improving the energy performance of the inverter and simplifying, form the above two modulated pulse sequences with a repetition period 60 e. hail, in the first of which the modulation law corresponds to the value of a sinusoidal function on the interval of 0-60 el. degrees, in the second of which the modulation law corresponds to the value of the sinusoidal function on the interval of 60 - 120 el.grad, forming six unregulated pulses of duration 60 el. hail, shifted from each other by 60 el.grad, and on the first interval of 0-60 el. hail for each valve of each phase of the inverter serves the first modulated pulse sequence, in the second interval 60-120 el.grad serves an unregulated impulse with a duration of 60 el.grad, in the third interval 120-180 el.grad serves the second modulated pulse sequence, in the fourth interval 180 - 240 electr grades are fed inversely relative to the first modulated pulse train; in addition, the modulation factor is changed by moving the leading edge of the pulses, and the intervals for each the inverter valve of each phase is carried out starting from the moment of passing the current value of the corresponding phase through zero. UUUUUtl fiyo.1 FI.2 "H J Puts . Tfa 53 TO jr 8 Z7 65 86 ST SS2 YH; M Ljl: i: Compiled by S.Luzanov Editor T.Lazorenko Tehred L.Serdyukova Proofreader L.Pilipenko Order 5807/51 Circulation 659 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 J figs J "f | / 5jj /.