SU1607065A1 - Transistor inverter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply and electric drive systems. The purpose of the invention is to reduce the weight and size and increase efficiency. The inverter cells of the converter are made according to the zero scheme on transistors and output transformers, the cores of which are made with mutually perpendicular fields created by the primary and control windings. The voltages on the secondary windings of the output transformers are algebraically summed in the load circuit. With the help of pulses from the control unit to the control windings of the output transformers, the magnetic conductors of these transformers are saturated at a given time interval, the magnetic coupling of the windings is broken, and the secondary windings for the external circuit represent only the resistance. 5 il.

Description

The invention relates to electrical engineering and can be used in secondary power supply and electric drive systems.

The purpose of the invention is to reduce the weight and size and increase efficiency.

FIG. 1 shows the scheme of the proposed transistor inverter with the number of cells equal to two; in fig. 2 - design of one of the output transformers; in fig. 3 - vector diagrams of induction cores of output transformers; in fig. 4, 5 - timing charts of the inverter and a variant of the control system.

The transistor inverter is connected to a power source and contains transistor switches 2–5 of direct current shunted by reverse diodes 6–9 saturated output transformers with primary windings 10–13 and secondary windings 14, 15 to which a load 6 is connected. Control windings 17, 18 transformers are connected to the outputs of the control unit 19, which generates a sequence of pulses 20 (Fig. 4). Transistor inverter operates as follows.

At the moment to, a control pulse is applied to the key 2 (3-5) (pos. 2i-25, fig. 4). The current flowing from the source 1 through the windings 10, 14 forms the first step of the output voltage. To eliminate the effect of the windings 15, 12, 13 of the inoperative transformer, at the same moment of time a current pulse is applied to the control winding 18 (17), which injects the core of this transformer into saturation (pos. 26, 27 of Fig. 4). For example, armor ferrite magnetic core consisting of two cups is taken as the core (Fig. 2). Power windings 12, 13, 15 (10, 11, 14) are wound on a bobbin and laid in the ring groove of the cups. The control winding 18 (17) is wound on a glued core, as on a toroidal one.

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 These two groups of windings create a coupling field, the inductions Bn and B. of which are orthogonal at any point of the magnetic circuit. Flowing through the winding 15, the magnetizing current creates induction V., and the current flowing through the control winding (Lig 3) And the 1-W power winding 1o (14) is chosen on the basis that even at maximum magnetizing current the core is not saturated. In this case, 1, W, control: the winding must, even in the absence of a magnetizing current, bring the induction of the core to saturation. With a saturated core, the magnetic coupling between the windings 5 and 12 13 (14 and 10, I) disappears and the winding 1 & for an external target, it represents only non-: significant active resistance, i At time t, control pulses are supplied to the transistor switches 3, 4, and the accelerator winding 18 of the winding 18 is removed. Since the primary windings 10-13 are made with the same number of turns, and the secondary windings with different (W, W, 4), anti-phase voltages that are subtracted on the windings 1o and 14 form the second output voltage level.

At time t2, the key 4 is turned on, the key 3 is opened. To eliminate the effect of the windings 10, 11 and 14 on the load current, a current pulse is applied to the control winding 17, which introduces the transformer core into saturation. The physics of the process is similar to that described. A third stage output voltage is created.

At the moment lc, the control pulse from the winding 17 is removed, but supplied to the key. The secondary windings 14, 15 are the sum of the voltages. As a result, a fourth stage of the output multistage voltage is formed. The falling part and the opposite half-wave of the output voltage are formed by switching the keys in reverse order (see Fig. 4). To maximally approximate a sinusoidal fourth, the output voltage level has a double duration, and in the interval t - t, o the zero level is entered.

The required sequence of control pulses (Fig. 4) is generated by the control system 19, consisting of a master oscillator 28, a pulse distributor 29 and a logical part 30 (fig. DJ. Not only the power amplifiers necessary for matching the outputs of the microcircuits

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The master oscillator 28 generates a sequence of pulses 20, which

they are distributed in time by a counter for nine and decimate Erms, which together with the outputs Po, Pb .-, Po form a distributor 29 of pulses.

The RS flip-flop of the logic part 30 is thrown every half-period to form the direct and inverse outputs Q and D. The control signals S2. S4, .., Sj7 are connected to the outputs of the Ro-P9 distributor and the outputs

The flip-flop Q Q expressions, obtained according to the timing diagrams of the operation in TPM, the windings 17, 18 are fed through current amplifiers, a known variant of which is shown in FIG. 5, pos. db The inverter circuit is operational and with active-inductive load. For conducting reverse currents are diodes L-Y. Orthogonal windings 17, 18 due to the quadratic dependence of the resulting

20 core induction from. its constituents do not need to be monitored.

sign of load current., „„

The required number of turns of the control windings 17, 18 is selected from the condition of ensuring the saturation of the core liver.

The ratios of the numbers of loops 10, 11, and 14, 12, 13, and 15 are chosen from the condition of maximum approximation of the sinusoid by a square-step output voltage.

30 The absence in the proposed transistor inverter of the influence of inactive output transformers on the output signal form allows avoiding an additional transistor with a reverse diode in the zero push pull circuit of a separate cell, which reduces the mass and gaarite and improves efficiency.

Claims (1)

Invention Formula , n A transistor inverter containing several inverter push-pull cells with output transformers, the secondary windings of which are connected in series and connected to the output terminals of the inverter and the control unit, which is different 45 that in order to reduce mass and dimensions and to increase the efficiency, the output transformer of each cell is equipped with a control winding connected to the output of the control unit and located on the magnetic conductor of this transformer so that the magnetic flux generated by it is perpendicular to the magnetic flux generated by the primary windings of the output transformer. I sixteen d 15 FIG. 2 1 X Fig.: 5 ID  - | TlA " -uJ - flTsa l, le „Ч„ Г