SU568123A2 - Transistorized voltage converter - Google Patents

Description

(54) TRANSISTOR VOLTAGE CONVERTER

The invention can be used for the hcTO iHKKax power supply of electronic equipment for various purposes.

According to the main auth. No. 233072 is known for a converter made according to a two-circuit scheme, two sections of the primary winding of the output transformer of which are used as the windings of positive feedback circuits, and the secondary winding is connected to a two-phase rectifier with a capacitive filter.

This efficiency increase device is equipped with a double-winding commutating choke with a core of a material with a rectangular hysteresis loop, the windings of which are connected to the auxiliary windings of the output transformer of the converter via diodes and transitions of the emitter-base of the transistors of the converter.

The use of a commutation throttle reduces the losses in the transistors, as it allows to obtain the optimal switching time of the transistors. The transformer parameters do not affect the switching frequency of the transistors, which allows selection.

For him, the optimum mode of operation and increase the efficiency of the converter.

However, in practical schemes, the processes are more complicated and due to the use of ferromagnetic materials for commuting droplets, the magnetization reversal curve of which differs from the rectangular one, and also because of the voltage drop across the diodes and at the base-emitter junctions of the transistors.

The time of magnetization reversal in each half-period depends on the voltage, the base-emitter of the transistors and the voltage drops on the diodes and, due to their scatter, is different in magnitude. This leads to a misalignment of the circuit, which has led to an increase in losses in the window of transistors, / an increase in the switching current and a decrease in the reliability of the circuit.

The aim of the invention is to increase the efficiency of the converter and improve its reliability.

For this, an additional winding is introduced into the switching choke, which is connected to the auxiliary winding of the transformer and can be connected via a single-resistor chain. The drawing shows a schematic diagram of a converter, in a half bridge version. The converter is made of transistor 1 and 2 and is equipped with an output transformer 3. Primary 4 of transformer 3 is included in the diagonal of the bridge formed by capacitors 5 and 6 and i in transistors 2. Winding 7 to 8 are used as positive feedback windings. The secondary winding 9 of the transformer 3 is connected to a rectifier on a dyuah 10 n 11 capacitor filter across a capacitor 12 connected in parallel to the load (same 13. In the converter use a three-winding choke 14. Obmops 15 drossel 14 is connected to the auxiliary winding 16 of transformer 3 through diode 17 and a junction i base of the transistor 1, and the winding 18 of the drossel 14 - to the auxiliary winding 19 through the diode 20 and the transition bae-vmitt transistor 2. A third winding 21 of the throttle 14 is connected through the diode-resistive chain 22 with the auxiliary winding 23 of the trans The device works with a transducer image Transistors 1 and 2 each 1) are usually connected to the capacitors 6 and 7 of the transformer 3. When you have a VNI, for example, vpaHSKCffOpa 1 nqp- the main winding is connected to the co-ordinator S. Basic transistor 7 transformer, winding 21 droplets 14 applied voltage auxiliary winding 23. Under the action of this voltage choke reversal and when it reaches saturation "through the winding 16 of the transformer increases sharply, which leads to locking nsistor 1 and to roll over the converter. Then, transistor 2 is turned on, and the process is similar. The voltage on the winding 23 of the transformer is chosen greater than the sum of the auxiliary winding voltage (16 or 19) and the maximum possible base-emitter voltage for this type of transistor. As a result, the voltage across which the choke is re-magnetized does not depend on the base-emitter voltage of the transistors and the voltage on the diodes of the base-emitter shunt transitions, and thus eliminates one of the main causes of skewing. For example, when the transistor 1 is turned on, the current in the circuit 15 and 16 does not flow through the entire half cycle, since the voltage on the drossel winding is greater than the sum of the voltage on the auxiliary winding 16 and the base-emitter voltage of the transistor 1, and the circuit is locked with a diode 17. Magnetizing gok flow through the circuit obtomatszh 21 (choke) and 23 (transformer). To increase the reliability of the converter under serial production conditions, when there is a possibility of installing transistors with extreme parameters (for example, with a minimum and maximum resorption time) in the transistor bins, various asymmetrical chains, such as diodes and potentiometer 22, connected in series with windings of the throttle and transformer, Formup of the invention 1. Transistor voltage converter according to the author. swith No. 233072, which is based on the fact that, in order to increase efficiency and reliability, the choke and the transformer are provided with additional windings, which are connected opposite to each other. 2. The converter according to p. Ij is of a kind, and with the fact that, for the purpose of additional correction, the indicated windings of the throttles and traisformat1 are connected {s via a diode resistive chain.