SU1446673A1 - Device for protecting from unidirectional saturation the power transformer of pulsed converter - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to simplify a device for protection against unilateral saturation of a power transformer of a DC voltage converter. During the pause in the operation of the key elements 4 and 5 of the converter 3, the voltage on the second winding 12 of the throttle locks the power diodes of the slider 6. In this case, the magnetizing current of the transformer 2 passes through the diodes 1, the key 9 and the current limiter 10, the limiting threshold of which is equal to the maximum current magnetization. After the pause, the key 9 is closed by applying a locking voltage equal to the sum of the voltage on the secondary winding of the transformer 2 and the voltage on the second winding 12 of the LC filter 7 throttle 7, and the protection device does not affect the operation of the converter 3. 2 h. P. f-ly. 1 il. i SP

Description

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The invention relates to converter equipment and can be used in sources of secondary electric power supplies with a transformer at the output.

The purpose of the invention is to simplify the device for protection against unilateral saturation of the power transformer

constant voltage converter,

The drawing shows a circuit diagram of a converter with a protection device.

The protection device comprises a rectifier 1, an input connected to one of the windings of the power transformer 2 of the converter 3, key elements 4 and 5, an inverter 6 of the converter, a smoothing LC filter 7 and a control unit 8. The output of rectifier 1 is shunted by series-connected key 9 and current-limited BaioiJUiM 10 elements. A diode is used as the key element 9. An additional winding of 11 droplets of the LC filter 7 of the converter 3 is connected between the common point of the key 9 and the current-clamping 10 elements: and the input terminal of the chokes of the HC filter 7 of the converter 3,

As a current-limiting element can be used, nap-: |) nmer, current stabilizer.

The device works as follows.

At the moment of pause. In the operation of the key elements 4 and 5 of the converter 3 ,. the duration of which is determined by the control unit 8, opens the key element 9. The element 9 is opened by flowing the load current of the converter 3 through the key element 9 and additionally introduced by the winding I1 of the chokes of the LC filter 7, which locks the diodes of the voltage of the converter 6 by voltage arising on it at the moment of pause, the polarity of which is indicated on the diagram in parentheses. Since the diodes of the rectifier of the converter are locked at the moment of pause by the voltage on the additional winding 11 of the choke of the LC filter, the magnetizing current in the power transformer 2 flows through the rectifier 1, the key 9 and the current-limiting 0 elements.

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The limiting threshold of the current-limiting element 10 is chosen to be equal to the maximum permissible magnetizing current 1 | q d, o, c, corresponding to the maximum permissible in the given induction transformer. If the current 1p is less (lm, then the current-limiting element 10 is saturated and the flow of current i / does not cause a noticeable voltage drop on it, and therefore a minimum voltage is applied to the corresponding winding of the power transformer 2 of the converter 3, equal to the sum of the voltage drops on the top - Receiver 1, key 9 and current-limiting elements 10. This voltage, due to its smallness, practically does not reduce the current ip, and consequently, the magnitude of induction in the core of the power transformer 2. However, if the current if / exceeds Ini ijUMoiKt, the current-limiting element 10 limits the current through rectifier 1 at the in level. An excess of current (if / -) flows through rectifier 6 of the converter and enters the load. At the same time, demagnetizing voltage is applied to the secondary winding of the power transformer 2 equal to the voltage on the additional winding 11 chokes of the LC filter 7, and the current begins to decrease with a speed diJd / dt equal to

di / i (Up "3M dt ™ -L -

where L c is the magnetizing inductance of the power transformer 2, reduced to the corresponding winding.

The pause value is chosen such that by the time of its termination the current i | u becomes less than 1 / | iax. This ensures that the current i is found, and consequently, induction in the core of the transformer is within the specified limits, which eliminates one-sided saturation of the power transformer 2. After the end of the pause, the key element 9 is closed by applying a locking voltage equal to the sum of the voltage on the secondary winding of the transformer and the voltage on the additional winding I1 droplets of the LC filter 7 whose polarity is shown in square brackets, and

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the protection device does not affect, for the purpose of simplification, the throttle of the gluttonous converter 3, the living LC filter, is entered into the second

Claims (2)

winding, the first conclusion is intended - the claims of the invention for connection to the multi-variable the conclusion of the first winding mentioned 1, Device for protection against single-stranded and cathodes of power diodes, third-party saturation of a power trans- meter with a second one connected to the first pulse-transformer format converter of the key element and through a constant voltage with an IQ pause current-limiting element connected to the operation of power key elements on the cathodes of the first and second diodes connected to the primary stages of the cathodes, while the anodes of these diodes are coils of a power transformer, and are intended to be connected to the extreme winding of which These conclusions conclusions silovo- house the secondary winding is connected to the negative The output transformer is of transducer nym output transducer, and extreme and a second terminal key element - two terminals connected to the anodes to its average conclusion power diodes whose cathodes through 2. The device according to claim 1, 1 and 2 - the first winding of the throttles is smoothed so that the key LC filter connects to the positive element 20 as a diode, the output output of the converter, 3, The device according to paragraphs. 1 and 2, which contains the first and second diodes, characterized in that the current-limiting and key element- limiting element is made into one, characterized in that, in the form of a current stabilizer.