SU1411895A1 - Single-ended transistor d.c. voltage converter - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase reliability by reducing the dynamic power losses during switching of the power transistor and expanding the range of control of the rate of increase of the output voltage at the start. The converter contains a power transistor 1, via a power choke 2 connected to the input ports. Parallel to the power transistor 1, a chain of a series of connected shunt capacitor 3 and shunt diode 4 is connected. The charge of the shunt capacitor 3 starts through the shunt diode 4 with a current, the initial value of which is equal to the sum of the current flowing through the power choke 2 and the reduced load current, 3 sludge. $ (L

Description

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The invention relates to electrical engineering and can be used in secondary power supply systems for converting a constant voltage.

The purpose of the invention is to increase reliability by reducing dynamic power losses when switching a power transistor.

FIG. Figure 1 shows a schematic diagram of the power part of the proposed (second converter; Figures 2 and 3 are diagrams of currents and voltages in the converter circuits in transition and established processes, respectively.

The voltage converter contains a power transistor 1, the emitter of which is connected to the negative terminal of the power source, and the collector through the power choke of its 2nd positive terminal. Parallel to the power transistor 1, a chain is connected | from a series-connected shunt-I capacitor 3 and shunt diode 4, the cathode of which is connected to the negative terminal of the power source, and the positive end of the latter is connected to the cathode of the discharge diode 5. Anode discharge diode 5 unite with one of the terminals of the buffer capacitor 6, the second output of which is connected to the point of connection of the shunt capacitor 3 with the anode of the shunt diode 4, and connected to the cathode of the cutting diode 7, the anode of which through will add A solid choke 8 is associated with a negative output of the power supply. Parallel to the power transistor 1, a unit for converting a pulse voltage to a constant is turned on. This unit is for the upgrade (the converter is made in the form of successively connected power Yiod 9 and filter output capacitor. Sensor 10 and is connected to the load 11. For the converter with a split capacitor (Cook scheme), the circuit of this unit is, respectively, - .keHBHa.

The transistor converter in: transition mode works as follows (& bit.

At the time of locking the force: b o transistor 1 t (figure 2) its collector current (Figure 2a), equal to (|: the current flow through the power choke 2 (figure 2b and reduced load current, drops to zero)

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(the decay time is determined by the frequency properties of the power transistor 1 and is assumed to be zero). This starts the charge of the shunt capacitor 3 through the bypass diode 4 (Fig. 2e, g) with a current, the initial value of which is equal to the sum of the current flowing through the power choke 2, and the reduced load current. Consequently, the voltage on the power transistor 1 (Fig. 2c) does not increase abruptly, but repeats the voltage Uj on the shunt capacitor 3 (Fig. 2d), thereby creating a favorable turn-off path of the power transistor I.

From the moment t-, when the charge of the capacitor 3 is finished, until the moment when the power transistor 1 is turned on, the current in the power choke 2 is closed in the circuit; power choke 2 - l power diode 9 - capacitor 10 - power supply. At the moment of turning on the power transistor 1 (C), the voltage and (Fig. 2c) drops to zero (the decay time is determined by the frequency properties of the power transistor 1 and is assumed to be zero). This starts the discharge of the shunt capacitor of the torus 3 in the circuit: shunt capacitor 3 — power transistor 1 — additional choke 8 — cut off diode 7 — buffer capacitor 6. Energy stored in shunt capacitor 3 is transferred to the buffer capacitor 6.

At time t, when the voltage on the shunt capacitor 3 in the oscillatory process of its discharge drops to zero, the shunt diode 4 opens and the charge of the buffer capacitor 6 continues in the circuit: buffer capacitor 6 - shunt diode 4 - additional choke 8 - cut off diode 7 due to the energy stored in the additional choke 8. The shape of the collector current 1l of the power transistor 1 is determined by the parameters of the circuit: shunt diode 3 - additional choke 8 - cut-off diode 7 - buffer capacitor 6, as well as pairs TRAM circuit choke and the load 2.

In steady-state mode, the nature of the processes in the transistor key depends on the ratios of the power supply voltages and the maximum value of the UEM voltage on the capacitor 3

(Fig, 3). FIG. 3 shows time diagrams of the processes for the ratios and 7 2E (Fig. 3a) and V, 2E (Fig. 36).

In the case of / 2E, when the power transistor is locked, a shunt capacitor is charged in a loop: power choke 2 — shunt capacitor 3 — buffer capacitor 6-10 discharge diode 5, while the voltage on the buffer capacitor b decreases from E + to E ( time t, fig. 3). The subsequent charging of the shunt capacitor 3 to the voltage 15 and carried out along the circuit: power source - power choke 2 - shunt capacitor 3 - shunt diode 4. When the voltage is reached

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on the shunt capacitor of the magnitude and ... further on, the entire current of the power

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Drossel flows into the output circuit.

When the power transistor is unlocked, the discharge of the shunt capacitor 3 occurs along the contour :, shunt capacitor 3 — additional choke 8 — cut-off diode 7 — buffer capacitor 6. In this case, energy from the shunt capacitor 3 is transferred to the buffer capacitor 6, charging up to voltage, a little more than E. At time t (Fig. 3a), when the sum of the voltages on the buffer and shunt capacitors is equal to E, discharge diode 5 is unlocked and the remaining energy in the additional choke is sent to the power source through the cut-off 7 and bit 5 diodes.

When and. 2E, the processes in the circuit occur similarly, with the difference that at the moment of locking the power transistor a jump in voltage occurs on it (fig.zb). The voltage across the shunt capacitor varies in

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A transistor single-voltage DC / DC converter containing a power choke, connected by one output to the first input output of the converter, and another through a power transistor to the second input output of the converter, and an additional choke connected by the first input to the second input output through the second input output of the converter, and an additional choke connected by the first input to the second input output through the second input terminal of the converter. and the second output through the first and second diodes connected in series to each other, connected opposite to the converter power supply, to the first input output of the converter the first point of shunt capacitor is connected to the point of connection of the power droplet with the power transistor, and parallel to the power transistor a pulse voltage conversion unit is connected, in order to increase reliability by reducing the dynamic power loss when switching power transistor and expanding the range I of regulating the rate of rise of the output voltage during start-up, a buffer capacitor is inserted, one output of which is connected to the junction point of the first and torogo diode and the other terminal connected to the second terminal of tundiapazone (E-4U) to (E + di). For example, a –4 capacitor capacitor, and through the introduction of a third diode modified on a buffer capacitor, switched on in the range from E to E + li. In accordance with the direction of conductivity.

Without taking into account the energy loss in the commutation-power transistor, with the second input circuits for voltages, the appropriate output of the converter.

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condition 4U 4l -f / jU is satisfied. The energy of the additional throttle 8 in this mode is not transmitted to the power source.

In this way, the dynamic losses during switching of the power transistor are reduced, which increases the efficiency and reliability of the converter.

Claims (1)

Invention Formula A transistor single-voltage DC / DC converter containing a power choke, connected by one output to the first input output of the converter, and another through a power transistor to the second input output of the converter, and an additional choke connected by the first input to the second input output through the second input output of the converter, and an additional choke connected by the first input to the second input output through the second input terminal of the converter. and the second output through the first and second diodes connected in series to each other, connected opposite to the converter power supply, to the first input output of the converter the first point of shunt capacitor is connected to the point of connection of the power droplet with the power transistor, and parallel to the power transistor a pulse voltage conversion unit is connected, in order to increase reliability by reducing the dynamic power loss when switching power transistor and expanding the range I of regulating the rate of rise of the output voltage during start-up, a buffer capacitor is inserted, one output of which is connected to the junction point of the first and torogo diode and the other terminal connected to the second terminal A tunyU . / I l. / L % "4" -7n / N / U f t