SU1418875A1 - Inverter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power sources of automation devices and computer technology. The purpose of the invention is to increase reliability by eliminating through currents while expanding the control range. The inverter is made by bridge circuit transistors 1-4. The AC diagonal inputs are connected to one of the inputs of the transistor 8 state sensors; 9 other inputs of which are connected to the middle points of capacitive voltage dividers 14. The outputs of these sensors are connected to the blocking inputs of control signal formers 6, to the information inputs of which signals are taken into account with 7 pulse-width modulators. The introduction of transistor state sensors allows the switching on control signal to be applied to the next transistor after the previously turned on transistor of the adjacent arm is completely turned off in both regulated and non-regulated converters. 2 3.p. f-lsh, 1 ill. i (L

Description

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The invention relates to converter equipment and can be used in secondary power sources of automation and computing devices.

The purpose of the invention is to increase the reliability by eliminating through currents while expanding the range of regulation.

The drawing shows the electrical circuit of the inverter.

The inverter is bridged by transistors 1-4 connected to control unit 5, consisting of four identical control signal formers 6 and a pulse width modulator (PMM) 7,

Transformers 8 and 9 are used as transistor status sensors. Each transformer has one primary winding (state sensor input) and one secondary winding with a middle point (state sensor output} loaded on active resistances 10 and 11,

The primary winding 12 of the transformer 8 is connected through capacitors 14 of a capacitive divider to transistors 1 and 2, and the primary winding 13 of a transformer is connected to another pair of transistors 3 and 4 through another pair of capacitors 14 of the same capacitive voltage divider.

The secondary windings of transformers B and 9 receive information about the voltage of an adjacent pair of transistors, which is transmitted to control unit 5 at the inputs of the comparators 15 of the drivers 6. The outputs of the comparators 15 of the drivers 6 are connected to one of the inputs of the AND-HI circuit 16, the other inputs of which are (information) connected to the corresponding outputs of the control pulse PWM 7, the outputs of the AND-16 circuits are connected to one of the inputs of the RS flip-flops 17, the second inputs of which are connected to the second inputs of the AND-NOT circuits. The output diagonal of the bridge is connected via output transformer I9 to the terminals for connecting the load. i

PIM 7 generates control signals corresponding to the numbers of transistors 1-4, the phase shift between which is carried out according to the principle of pulse-width modulation.

The output two-polar signals of the amplifiers 18 of the pulses of the driver 6 correspond in duration to the output signals of the triggers 17.

The inverter works as follows.

Suppose at time t, the control pulses are applied to the bases of transq 1 and 3, the latter open and current flows through them, and the input voltage of the converter appears on the load. At time t, a trigger pulse is removed.

5 controls from transistor 3 and a locking pulse is applied, but transistor 3 remains in the open state until the process of resorption of minority carriers is completed

0 of its base. This process ends at time t, when the base-emitter junction is restored. After time tj, the voltage across the transistor begins to recover. Signal,

5 removed from the secondary winding of the transformer 9 and repeating the voltage change on the switching transistor 3, is fed to the input of the comparator 15 of the driver 6 pulses. At the output of the comparator 15, a logical signal 1 is generated at time t, when the voltage reaches the setpoint value.

The comparator signal is fed to

, one of the inputs of the circuit 16, to the other input of which a pulse of PWM 7 comes. The output signal of the circuit 16 overturns the trigger 17 and forms the leading edge of the trigger pulse of transistor 4, delayed relative to the back edge of the trigger pulse of transistor 3 on frame t race t - tj. After turning on the transistor 4, the circuit is organized

5 of the load through the transistor 4 turned on in the inverse turn on and the transistor 4 connected in the forward direction. There is a pause in the output voltage on the load. Then, the pulse shaping signal of the transistor 1 is removed by the pulse generator 6, but the transistor 2 is turned on after time t race t JPCT transistor 1, and so on.

Thus, the introduction of transistor state sensors, which measure the voltage across the transistors directly, makes it possible to supply

including a control signal to the next transistor after a complete turn-off of the previously turned on transistor adjacent to it, which ensures the complete elimination of through currents in both regulated and unregulated bridge and half-bridge transistor inverters and increases the reliability of the latter.

In addition, transistors 1-4 are additionally loaded with the magnetizing current of the sensor transformers 8 and 9, the amplitude of which at the moment of switching off does not depend on the load current of the inverter and the output ratio of the output voltage. This reduces the dissipation time of transistors 1–4, which makes it possible to increase the inverter control range in the direction of small conduction angles of transistors without disturbing their normal switching cycle.

In the inverter operating in the pulse-width modulation mode, the mode takes place when either a pair of transistors 1, 4 or 2, 3 is turned on, then a pause occurs in the output voltage of the inverter and the current through the inverter's transistors is provided with stored energy in the inductance of the transformer 19 In this mode, the magnetizing current of the transformer is closed both through the switched-on pair of transistors on one pair of power lines and through the load. If the pause is long., Then the current time drops to zero, and the transistors remain in the on state without current at the impulses of control, i.e., go into deep saturation mode with large multiplicity. This leads to a significant increase in the turn-off time of the transistor when a blocking control pulse is applied to its input. If the turn-off time of the transistors exceeds the duration of the control pulse of the next transistor, then a failure occurs: normal cycling

cheni inverter.

Installing an air gap transformer as a sensor allows loading the transistors with reactive current independent of the load size and the depth of the inverter control, which allows normalizing the turn-off time of the power transistors, thereby not

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Claims (3)

1. An inverter, produced by a bridge transistor circuit, one diagonal of which is connected to the output pins, and the other to the input, shunted by the first capacitive voltage divider, the midpoint of which is connected to one of the input transistors, the second inputs of which are connected to the corresponding output terminals of the inverter, and the outputs of the said sensors are connected to the corresponding blocking inputs of the first two control signal drivers, the information in the strokes of which are connected to the output of the pulse-width modulator, and the outputs of the control signal drivers are connected to the transistors of the opposite shoulders of the bridge, characterized in that, in order to increase reliability by eliminating the through currents when the control range is expanded, the third and fourth control drivers are inserted signals similar to the first two, with the blocking inputs of control signal drivers for transistors of adjacent antiphase arms connected to paraphasal sensor outputs s state of these transistors shoulder and the first input of the second sensor vshod state transistors connected to an intermediate point of introduction of the second capacitive voltage divider connected in parallel to the first. 2. An inverter as claimed in Claim 1, characterized in that voltage transformers c are used as transistor state sensors. air gap. 3. The inverter according to claim 1, characterized in that each of the control signal drivers contains a comparator, an NAND circuit, an RS trigger, and an output amplifier, one of the inputs of the comparator forming the specified blocking input of the control signaling generator, and the other to the output for connecting the reference signal, the output of the comparator 51418875 connected to the first input of the I – PE circuit, the first input of the R-Trngger, the output of the second input of which forms the information through the output amplifier of the power input of the control driver is connected to the output of the flashing signal and the output to .. the body of control signals.