SU467277A1 - DC power converter - Google Patents

Description

one

The invention relates to the field of measuring technology and can be used as a measuring transducer for linear conversion of an input DC voltage to an output DC voltage with galvanic separation of the input and output circuits. In particular cases, the converter can be used as a scale link or a galvanic separator of electrical high-current and low-current circuits, and also as a part of telemetry systems and digital measuring devices.

The known linear DC / DC converter containing a series-connected switching device, a transformer, a rectifier and a filter, a multivibrator does not provide the necessary conversion accuracy, since the frequency of the multivibrator does not remain constant when the supply voltage changes.

In order to increase the conversion accuracy, a voltage transformer and an inverter have been introduced into the converter, and the multivibrator is connected via an inverter and a voltage transformer to the control input of the switching device.

The drawing shows the described transducer containing multivibrator 1 (transistors TI, Tz) of inverter 2 (transistors T3, T4), switching device 3 (transistors TS, Tg), transformers 4 and 5 of galvanic separation of input and control circuits, rectifier 6 ( diodes D,

D2) and filter 7 (resistor Ri, capacitor Ci). When the DC voltage is turned on, the multivibrator begins to generate square-wave pulses, the duration and frequency of which are determined by the parameters of the pulsed bridge elements included in the base-collector connections of the TI and T2 transistors. This ensures the stability of the threshold for unlocking the bridge diodes Dz, D4, and the frequency of the multivibrator remains unchanged with changes in the power supply pair.

From the collectors of the latter, pulses arrive at the bases of the Ta, T4 inverters, in whose collector circuits the primary winding is connected with the middle point of the transformer 5. The inverters are used to eliminate the instability of the multivibrator from its load. Medium point secondary

Transformer 5 induces rectangular pulses due to the operation of the transformer on the linear portion of the magnetization curve. These pulses, arriving at the base of the TS transistors, Te, provide them

high stability switching

both in duration of open and closed state, and in frequency.

A measured DC voltage is supplied to the converter input, which, switching alternately by TS, Tb transistors, is supplied through ballast resistors to the primary winding with the midpoint of the transformer 4.

On the secondary winding with the midpoint of the transformer 4, rectangular pulses are induced with an amplitude proportional to the input voltage t / I. This transformer also operates in a linear part of the magnetization curve, due to which a linear dependence of the output voltage on the input voltage is realized.

After the transformer, the pulses are rectified by diodes D ,, Dz and are smoothed by a filter (resistor RI, capacitor Ci), forming the output DC voltage

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Prevention: Retenie

A linear voltage converter, voltage, containing a successively connected switching device, a transformer, a rectifier and a filter, a multivibrator, characterized in that, in order to improve the accuracy of the conversion, a voltage transformer and is introduced into it. the inverter, with the multivibrator connected

through the inverter and the transformer. voltage with the control input of the switching device.