SU974549A1 - Control system for self-sustained thyristorized inverter with high-frequency intermediate state - Google Patents

Description

(5) CONTROL SYSTEM OF THYRISTOR AUTONOMOUS INVERTER WITH INTERMEDIATE LINK

one

The invention relates to a converter technique and can be used in thyristor devices for private control of asynchronous motors, as well as for on-board power supply systems with small weights and dimensions.

In most cases, three-phase bridge circuits 1 are used as the power circuit of autonomous thyristor inverters.

However, if along with adjusting the output voltage and frequency, it is necessary to reconcile the voltage value of the inverter power source and the voltage value of the inverter power source and the voltage generated on the load, while the weight of the barometric indicators of the device is reduced, it is advisable to use an inverter with an intermediate link high frequency, consisting of a single-phase high-frequency bridge inverter, transformer and frequency HF

switch To control the inverter according to the specified power circuit, it is advisable to apply PWM by forming an output voltage half-wave of equal duration rectangular pulses whose duration is equal to the duration of the control pulses C2.

The closest to-proposed is an autonomous inverter control system implementing PWM that performs a discrete increase in the ratio of the carrier frequency of control pulses to the output frequency of the inverter in the lower frequency range of the inverter compared to the upper ones. The said control system for an autonomous three-phase thyristor inverter made in a three-phase 2 (j circuit, contains a master oscillator connected to a frequency divider with intermediate outputs, the output of which is connected to a scaling circuit with modulating signal generator for 397 cathode and anode groups of thyristors of each phase, unit switching carrier signals containing a single vibrator to the inputs of which the input of the master oscillator and the outputs of the frequency divider, as well as shapers of wide and short pulses are connected thyristor control systems containing circuits And A disadvantage of the known control circuit is that it does not have the necessary functionality to control an autonomous thyristor inverter with a high-frequency intermediate circuit consisting of a single-phase bridge high-frequency inverter, a transformer and a thyristor switch with current sensors. of the invention is the expansion of functional capabilities. To achieve this goal, the control system of the thyristor autonomous inverter with a high frequency element consisting of a single-phase bridge high-frequency inverter, a transformer and a thyristor switch with current sensors containing a master oscillator connected to a frequency divider with intermediate outputs, the output of which is connected to a scaling circuit with modulators of modulating signals for the cathode and the anodic thyristor groups of the switch of each phase, a clock switching unit containing a one-shot, the inputs of which are connected to the input of the master oscillator and the outputs of the clock divider The voltages, as well as wide and short thyristor control pulse drivers, containing AND circuits, connect the single vibrator outputs to the inputs of the high frequency inverter thyristor control drivers and shapers, and a single inverse trigger output connected to the input of the first short pulse control inverter outputs of the high frequency inverter to the output of the clock switching unit, and the inputs of the other two short thyristor control pulse drivers are high The invertors are connected to the second one-shot through two sequences. flax delay lines, while the outputs of the circuits AND shapers of the wide control pulses of the thyristor switch are connected to the outputs of OR circuits 94, which form the modulating signal of the anodic or cathodic group of this switch phase, the first one-shot output and the single inverse output of the trigger, and the inputs of the AND circuits The outputs of current direction indicators of this phase, the second output of the one-oscillator, and the inverse single output of the trigger are connected to each driver of the narrow control pulses of the thyristor switch. FIG. 1 shows the power circuit of an autonomous thyristor inverter with an intermediate high-frequency link; in fig. 2 is a block diagram of the proposed inverter control system; in fig. 3 is a timing diagram of the signals of the proposed control system. Autonomous thyristor inverter (Fig. 1) consists of an intermediate high-frequency link, including 1-A power thyristors, reverse diodes, switching thyristors, respectively, for switching cathode and anode groups 9 and 10, diodes 11 and 12, switching chokes 13 and 14, switching capacitor 15. Transformer 16 contains a winding 17 connected to the output of a high-frequency link, as well as winding 18-23, to which a thyristor switch consisting of thyristors 2435, a three-phase load 36-38 connected in a star and current sensors is connected and amplifiers of their signals, respectively 42-44. The block diagram of the proposed inverter control system (Fig. 2) contains a master oscillator 45, a frequency divider 46, presented in the form of three series-connected thyristors 47-49, a scaling circuit (shift register) 50 with a modulating signal generator for the anode and cathode thyristors each phase (OR circuit 51-56), clock switching unit 57, which includes semiconductor relays 58 and 59, whose outputs are connected to control inputs of two key groups 60 and 61 and 62, 63, OR 64 circuit, to the entrance of which is directly The final output of the frequency divider and its intermediate outputs is connected through the keys 60, as well as the one-shot B5, the first input of which is connected to the output of the block via the delay line 66, and the second and third to the outputs of the keys B2 and 63, the control unit 67 of the single-phase high-frequency inverter Of the flip-flop 68, two shapers of wide control pulses 69 70 with the And circuits connected at their inputs and three shapers of short control-5 impulses of control, of which two

The latter are connected via successively connected lines of Delay 7b-77,

Identical blocks 78-83 of wide and short impulse control formers 10 of the anodic and cathodic groups of the switch thyristors with circuits I included at their inputs

The proposed control system for the autonomous thyristor inverter operates as follows.

The master oscillator 5 generates a sequence of impulses, which goes to the frequency divider +6. The frequency divider, in its turn, forms three sequences of pulses with a frequency of 2kf, 12f, 6f, (where f is the inverter output frequency), which are presented respectively on FIG. 3 -. b, c. Pulses from the output of the divider k6 with a frequency of 6 f are fed to a six-cell shift register, the outputs of which include six circuits of the shaper modulators 51 56. The outputs of the OR circuits form a three-phase system of voltages shifted with each other by 120 °. FIG. Zg, d, e are the modulating voltages at the outputs of the odd OR circuits. The respective modulating voltages jj at the outputs of the even circuits OR are out of phase with the reduced voltage.

The final output of frequency divider 6f and its intermediate taps 12f and 40 2kf are connected to the input of the circuit OR 6 of the clock switching unit. At the same time, in the upper frequency range, relays 58 and 59 are closed, the intermediate outputs of the frequency divider are shunted and only impulses with a frequency of 6f arrive at the input of the OR circuit OR, only the relay 59 is closed in the middle frequency range and impulses of a frequency of 6f arrive at the input of the OR b , 12f, -. in the lower frequency range, both relays 58 and 39 are open and pulses with a frequency of 6f, 12f, Ztf arrive at the input of the OR 6 circuit. If the first group of keys 60 and 61 controls the frequency of the pulses taken from the output of the OR 6k circuit, then the other group of keys 62, 63 changes the duration of the carrier signals, initiated by the single vibrator b5.

For example, consider the operation of the control circuit in the middle frequency range, corresponding to which the graphs in FIG. 3. In this case, from the output of the switching unit of the clock signals 67 (the output of the circuit OR 6), the output pulses with a frequency of 12f are sent to the control unit of the high-frequency inverter, namely, the short pulse shaper 73, to the trigger, as well as to the single-frequency frequency input via the delay line 66 The voltage plots at one of the outputs of the trigger U 68 and at the first output of the one-shot Ub5 are shown in FIGS. 3, 3.

The trigger 68 and the one-shot B5 control the operation of the coincident circuits 71, 72, the output of which includes shapers of wide pulses 69, 70 controlling the power thyristors 1, k and 2, 3 of the high-frequency inverter. On the second output of one-shot1 | 6p a pulse is formed corresponding to the falling edge of the voltage taken from the one-shot, which through the delay line .76 goes to the driver of short pulses 7, goes to 77 via 77. Thus, at outputs b9, 70, 7 and 75 the necessary sequence of wide and short pulses is needed to control a single-phase high-frequency inverter, which forms a direct voltage with zero pause.

In this case, the signal duration of each of the delay lines 66, 71, 76 must correspond to the recovery time of the thyristors used in the inverter. FIG. 3 "shows the voltage U76 formed by line 7b. FIG. 3k is the voltage and. Generated at the output of the high-frequency inverter, where the diagram of the power thyristors is shown. It follows that during the formation of zero pauses after the recovery time of the thyristors k or 2, the anode pair of power thyristors 1 and 3c start the purpose of shorting the primary winding of the transformer along circuit 17-1 7, or. whereby regardless of the parameters of the load and the direction of the flow of reactive energy from the load to the source, a zero voltage is formed on the load.

The operation of the phase-by-phase groups of the control pulse formers of the thyristor switch 78-8} is considered on the example of blocks 73-79, which form the voltage on the load of CB 5 with the help of thyristors (Fig. 1) / I and the blocks 78 and 79 include -91, of which 92-95 wide-control pulse shapers are controlled, and 88-91 - short-control shaper shapers 96-99. The first inputs of the coincidence circuit .7 are connected to the output of the single vibrator, the second - alternately to the outputs of the trigger 68, and the third - to the form-15 of the modulating signal of the phase 36 of the scaling circuit. The diagram is. the point of potential a and the circuit of FIG. 1 of the inverter output is shown in FIG. 2. In FIG. 3c, t, graphs of linear-20 and phase voltages U at the load are available. The control pulses 1) 2, 27 arriving at the thyristors are shown in FIG. 3 liters, and, o. In accordance with the voltage at the output of the high-frequency frequency inverter of FIG. 3k, the potential of point a consists of six sequences, positive pulses and six sequences of negative pulses. The voltage from the outputs of the trigger 68 is, as it were. By analogy with the operation of the high-frequency inverter for the control system and in accordance with the operation of the high-frequency inverter, it controls the formation of control pulses fed to the switch tiris tors. The first inputs of the coincidence circuit 8891 are powered from the second output of the single-oscillator, through which a short pulse corresponding to the trailing edge of the single-oscillator pulse is formed, the second inputs are alternately connected to the trigger outputs, and the third to the outputs of the current direction amplifiers of this phase 42-4. The output voltages of the sensor currents are applied to the inputs of the current direction amplifier. The current direction amplifier of each phase has two outputs, while at some outputs of the amplifiers .2 W, V a signal is formed corresponding to a positive half-wave of the load current, and at their other outputs 2, 3, V - a negative half-wave of the load current. 8 areas of high and low frequencies change the pulse frequency at the output of the trigger and the one-shot, as well as the duration of the pulses,

formed by a one-shot, the principle of operation of the control circuit remains unchanged.

Claims (3)

The main features of the inverter control circuit from the prototype are as follows: the direct output of the frequency divider and its intermediate taps are fed to the input of the OR circuit, from which the trigger is triggered and through the delay line the one-shot; the introduction of a trigger that operates at the frequency of the high-frequency inverter and is the main control element for the AND circuits included at the inputs of the wide and short pulse control thyristors of the switch; switching on shapers of short control pulses with AND circuits switched on at the inputs controlled from current direction indicators, flip-flop outputs and second one-vibrator output, which ensure trouble-free operation of the inverter over the entire range of the inverter with a high-frequency intermediate circuit to active-inductive load; the presence of two single-shot outputs, the first output of which is the formation of the corresponding control pulse durations applied to the power thyristors, and the second output produces a short pulse along the falling edge of the generated pulse in order to receive short pulses from the additional driver at discrete points in time to switch the thyristors thyristor switch. The invention is a thyristor autonomous inverter control system with a high-frequency intermediate circuit consisting of a single-phase bridge high-frequency inverter, a transformer and a thyristor switch with current sensors, containing a master oscillator connected to a frequency divider with intermediate outputs, the output of which is connected to a driver with a generator circuit of modulating signals for the cathode and anode groups of the thyristors of the switch of each phase, the block JF of the timing signals containing one vibrator, which are connected to the inputs of input .zadayuschego generator and outputs of the frequency divider, and. Also, the wide and short thyristor control pulse shapers containing circuits AND, characterized in that, in order to expand the functionality, single-vibration outputs and a single inverse trigger output, whose input together with the first input, are connected to the inputs of the high-frequency inverter thyristor control pulse shapers the shaper of control pulses of the high-frequency inverter is connected to the output of the clock switching unit, and the inputs of the other two The short thyristor control pulses of the high-frequency inverter are connected to the second output of the single-oscillator via two successively connected delay lines, while the outputs of the circuits AND shapers of the wide pulses of the control of the thyristor switch are connected to the outputs of the OR circuit that forms the anodic or cathodic modulating signal. This phase of the switch group, the first one-shot output and a single inverse trigger output, and the outputs of the current-direction indicator indicators, the second one-shot output and the inverse single trigger output are connected to the inputs of the circuits AND of each pulse generator: controlling the thyristor switch: torus. Sources of information taken into account during the examination 1. Zabrodin Yu. S. Nodes of forced capacitor switching of thyristors. M., Energia, E7. 2. Authors certificate of the USSR ..., „.„ A., „,., Oi,“ and i. No. H 02 M 7/52, 1970. 3. USSR author's certificate No. 318127, cl. H 02 M 1/08, 1972.