RU1827707C - Single-ended transistor converter - Google Patents

Abstract

Usage: DC to AC conversion for secondary power systems, electric drives and automation. The inventive power transistor 1 is switched when the voltage polarity changes on the first secondary winding 3 of the control transformer 2. The second secondary winding 5 of this transformer automatically adjusts the saturation depth of the power transistor 1 using saturation dross 7 and the first diode 6. The third is secondary winding 11, having one or two orders of magnitude more turns than the second secondary winding 5, demagnetizes the saturation inductor 7 and forces the locking of the power transistor 1 at the junction the collector-base thanks to the small number of turns of the winding 9 of this throttle. 2 ill.

Description

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Yu VJ VI

ABOUT

The invention relates to a conversion technique and can be used in the development of switching power supplies.

The purpose of the invention is to increase the efficiency by reducing the static losses in the power key when the transistor is on and the dynamic losses when the power transistor is turned on.

Figure 1 presents a diagram of a device; Fig. 2 is a timing chart showing a comparative analysis of on-time, absorption of excess charge, formation of a positive collector voltage front and on-state static loss voltage.

The single-ended transistor power switch device comprises a power transistor 1, a control transformer 2, a first secondary winding 3 of a control transformer 2, a limiting resistor 4, a second secondary winding 5 of a control transformer 2, a first diode 6, a saturation inductor 7, consisting of two magnetos windings 8 and 9, a second diode 10, a third secondary winding 11 of the control transformer 2.

The device operates as follows.

When a rectangular pulse of positive polarity (time interval ti-t4, Fig. 2a) appears on the first secondary winding 3 of the control transformer 2, on its second 11 and third 5 secondary windings and on the windings 8 and 9 saturation throttle 7 induce EMF , the polarity of which is shown in Fig. 1 without brackets, Under the influence of a rectangular pulse of positive polarity, the base-emitter junction of the power transistor 1 is shifted in the forward direction and the base opening current JGH starts to flow through it, the value of which is limited to torus 4. B, as a result of this, the process of opening the power transistor 1 begins (time interval ti-t2, FIG. 2) and the collector current starts flowing through it. At the same time, under the influence of the EMF induced in the winding 11 and the EMF induced in winding 3, the current begins to flow along the following circuit: the beginning of the winding 11 of the control transformer 2 - winding 8 saturation throttle 7 - the first diode 10 - the collector-emitter junction of the power transistor V - the end of winding 3. As a result of the flow of this current in the winding 8 throttle saturation 7 there is an EMF, which in Este a voltage drop in the open

the transition of the diode 10 compensates the EMF induced in the winding 11. At this time, the current E of the circuit is maintained due to the open state of the diode 10. Compensation of the EMF winding

11 of the control transformer 2 prevents the shift of the base-collector junction of the power transistor 1 in the opposite direction, i.e. prevents the active operation of the power transistor 1. As a result, the power transistor 1 enters saturation mode (the base-collector transition is shifted in the forward direction) and is maintained in this mode until the inductor 7 enters saturated mode5 (interval time t2-ta of FIG. 2). The power transistor 1 entering saturation mode when turned on improves the negative edge of the collector voltage pulse (reduces the time interval

0 ti-t2, Fig. 2), reduces the loss of power to turn on (increases efficiency), reduces the instantaneous power dissipated by the power transistor 1 when turned on, i.e. increases reliability and efficiency. Finding

5 power transistor 1 in the time period t2-t3 in saturation mode reduces the static power loss on the power transistor 1 compared with the prototype by reducing the voltage drop by

At the base-collector junction of the power transistor 1. The number of turns of the first winding 8 and the inductance of the first winding U of the saturation choke 7 are chosen so that saturation of the choke occurs after

5 time is less than half the period, i.e. the number of turns of the winding of the first winding 8 and the inductance LS saturation choke 7 will be less than the number of turns and inductance of the second secondary winding 5

0 of the control transformer 2. In addition, the number of turns of the first winding 8, the inductance of the saturation choke 7 is chosen so that the EMF of the winding 8 of the saturation choke 7 is less than the EMF

5 of the second secondary winding 11 of the control transformer 2 for voltage drop across the diode 10 in order to ensure that the current flows through the saturation inductor 7, i.e. current through saturation inductor 7 and

0 the saturated mode of operation of the power transistor 1 in the time interval t2-ta (Fig.2d) is provided due to the open state of the diode 10. After saturation, the saturation choke 7 (time ta, Fig.2) is 5

the voltage on it becomes zero. Then, under the influence of the EMF on the second secondary winding 11, the base-collector junction of the power transistor 1 is shifted in the opposite direction and it enters an unsaturated (active) mode of operation (interval

time t3-t4, FIG. 2), which can significantly reduce the absorption time of the excess charge (time interval t4-ts, FIG. 2), the duration of the positive edge (time interval ts-te, FIG. 2), and as a consequence , reduces the power loss on shutdown in the time interval t4-t5, Fig. 2) and the instantaneous power in this time interval. Those. in this time interval, the proposed device retains all the advantages of the prototype.

When the collector current of the power transistor 1 changes, the device of the unsaturated key provides a redistribution of the base current of the power transistor 1 and the current flowing through the winding 8 saturation dross 7 and the diode 10, for example, with a decrease in the collector current of the power transistor 1, the current to its base decreases, and the current through the winding 8, saturation throttle 7 and diode 10 increase, as a result of which the inductor enters saturation mode faster (the time interval t2-ta decreases, Fig. 2). Since, in case of pulse-width regulation, a decrease in the collector current corresponds to a decrease in the open time of the power transistor 1 (time interval t2-t4, Fig. 2), when using the device in secondary power sources based on single-cycle pulse-width converters, in the case of changes in the load current over a wide range, the functioning of the proposed device is not disturbed,

The EMF induced in the winding 5 of the control transformer 2, keeps the diode 6 closed during the entire half-cycle of the positive control pulse (time interval trt4, Fig. 2) and accumulates energy for forced closing of the power transistor 1 during the half-cycle of the negative control pulse (time interval t4-ty, Fig. 2, a). Because to achieve greater efficiency of the absorption of the excess charge in the base-call% cto junction of the power transistor 1 during the half-cycle of the negative control pulse (increasing the blocking current at the base-collector junction), the winding 5 of the control transformer 2 is made with a large number of turns in compared with the winding 11 of the control transformer 2 (the voltage on the winding 11 has a value of the order of 2 V to achieve the optimal unsaturated mode in terms of static losses and time absorbed overcharge, since further increase in the voltage at the coil 5 decreases only insignificantly

the time of absorption of the excess charge and the duration of the positive front of the collector voltage with increasing static losses, and the voltage on the winding 11 can approach the supply voltage of the power transistor 1), and the winding 8 is the saturation choke 7 to ensure saturation of the interrogator and the open state of the diode 10 has fewer turns and inductance compared to the winding 11 of the control transformer 2 (voltage on the winding 8 saturation throttle 7 is less than the voltage on the winding 11 of the control transformer 2 n and the magnitude of the voltage drop across the diode 10) with the same material and the size of the cores, the demagnetizing winding 9 saturating throttle 7 will have a small number of turns and a small inductance compared to the winding 5 of the control transformer 2. At high voltage values on the winding 5 of the control transformer 2, the absorption current of the excess charge from the base-collector junction of the power transistor 1 during the half-cycle of the negative control pulse may exceed the base current of the power transistor 1 and the current through the winding 8 throttle saturation 7 several times, so the number of turns and the inductance of the demagnetizing winding 9 throttle saturation 7 will not exceed the number of turns and the inductance of its winding 8. The voltage on the demagnetizing winding 9 throttle saturation 7 will be insignificant compared to the voltage on winding 5 and, as a result, the demagnetizing winding 9, saturation throttle 7 will not affect the functioning of winding 5 during both positive and negative control pulses.

When a rectangular pulse of negative polarity appears on winding 3 (time interval t4-t, Fig. 2, a) on the second 11 and third 5 windings of the control transformer 2 and windings 8 and 9, saturation throttle 7 induces an EMF, the field The figure of which is indicated in parentheses in FIG.

Under the influence of the EMF induced in the winding 3 of the control transformer 2, the power transistor 1 closes at the base-emitter junction.

Under the influence of the EMF induced in the winding 11 of the control transformer 2, the power transistor 1 closes at the base-emitter junction.

Under the influence of EMF. induced in the winding 11 of the control transformer 2 is forced closing

diode 10 due to the fact that the voltage on the winding 11 is greater than the voltage on the winding 8 of the saturation choke 7, which contributes to the forced closing of the base-collector junction of the power transistor 1, because. the process of resorption of minority carriers of the diode 6 will not affect the process of resorption of minority carriers in the base-collector junction of the power transistor 1.

Under the influence of the EMF induced in the winding 5, the diode 6 opens. As a result, the reverse voltage is applied to the base-collector junction of the power transistor 1, which contributes to the fast absorption of minority carriers in this transition (reduction of the absorption time of the excess charge), reduction of shutdown power losses in the time interval t4-te (Fig. 2), t .e. an increase in efficiency, a decrease in the duration of a positive edge (time interval ts-t6, Fig. 2d), a decrease in instantaneous power at the shutdown stage (increase in reliability). Thus, the introduction of a demagnetizing winding 9 saturating throttle 7 does not affect the operation of the boosting winding 5 of the control transformer 2. Under the influence of the EMF induced in the winding 5 of the control transformer 2, during the action of the control pulse of negative polarity, demagnetization of saturation 7 throttle due to the leakage of minority carriers through its winding 9 in the base-collector junction of the power transistor 1 along the following circuit: end of the winding 5-winding 9 saturation throttle 7 - diode 6 - transition od collector-base power transistor 1 - the beginning of the winding 5. Since the magnitude of the dissipation current of minority carriers in the base-collector junction will be determined by the magnitude of the voltage of the winding 5 and the resistance of the circuit along which this current flows, then at high voltage values on the winding 5, the resorption current can exceed the base current and the current through the winding 8 several times, which ensures complete demagnetization of saturation throttle 7 even with fewer turns of its demagnetizing winding 9 compared to its main winding 8. The presence of the boost winding 5 of the control transformer 2 allows To some extent, reduce the time of absorption of the excess charge and the formation of a positive front of the collector voltage compared with the prototype.

When a positive polarity control pulse arrives, the processes occurring in the device are repeated.

Claims (1)

SUMMARY OF THE INVENTION A single-phase transistor converter containing a control transformer with two secondary windings, the first of which is connected to the base of the power transistor and the end through the resistor to the emitter of the power transistor, and the second end is connected to the base of the power transistor, and the first diode connected to the first output to the collector of the power transistor, characterized in that, in order to increase the efficiency, a saturation inductor with two windings is introduced, the first of which is connected to the second output by the first diode and the end is combined with the beginning of the second secondary winding of the control transistor, and the second end is connected through the introduced second diode to the collector of the power transistor and the beginning is connected to the end of the third secondary winding inserted into the control transformer, the beginning of which is connected to the base of the power transistor. Umvj Lt