SU1334307A1 - Single-phase stabilized d.c.-to-d.c.voltage converter - Google Patents

Abstract

The invention relates to electrical engineering, namely to power supply sources for studio television cameras. The purpose of the invention is to increase the electromagnetic compatibility of the converter with the powered television equipment by ensuring the constancy and synchronization of the conversion frequency. The converter contains the first transistor switch (TC) 1, the transformer 2, the current sensor 9, the comparator 10, the control pulse driver (IGF) 12, the feedback amplifier 13. The introduction of the second TC 11 and the connection of the IGF 12 to the driving input of the TC 11, Introduction of the master oscillator 14 and connection to TC 1 allows the duration of the recharging process of the capacitor 8 to be varied without energy loss and additional interference. TK 1 is locked at a constant frequency determined by the reference generator 14. TK 1 opens when the signals from the outputs of the logic element 11, current sensor 9 and comparator 10 coincide after overcharging of the capacitor 6. 2 Il. ate with 2 g4n "o with 4ib CO

Description

The invention relates to the industry of communications and can be used in the construction of sources for secondary power supply; - sound equipment of high frequency, such as studio television cameras,

The purpose of the invention is to increase the electromagnetic compatibility of the converter with the powered telezision: - equipment by ensuring the constancy and synchronism of the conversion frequency.

FIG. 1 shows a block diagram of a converter; Fig. 2 shows timing diagrams, in order for the converter to work (and the currents and voltages in combination correspond to the numbers of the elements).

The single-ended stabilized DC / DC converter contains the first transistor switch 1 connected in series and connected to the input terminals and the primary winding of the transformer 2e, the secondary winding of which through the first diode 3 is connected to the first capacitor 4 and the additional winding of the transformer 2 through an additional diode 5 is connected to an additional capacitor by capacitor b Diode 7 and capacitor 8 are connected in parallel with the leads of transistor switch 1 "Current sensor 9 is connected to common the additional winding point of the transformer 2 and the additional diode 5 voltage comparator 10 (for example, J semiconductor) inputs are connected to the additional winding of transformer 2, and the code is connected to one of the inputs of the coincidence logic element 11 and the input, the driver, 12 pulse pulses (for example

on the basis of a controlled one-shot), 45 on the windings of the transformer, the control output is connected to the output of the feedback amplifier 13. The output of the pulse driver is connected to the input of the second logic element 11 coincidence. The number of turns of the secondary winding of a transformer 2 divided by the number of turns of its primary winding is chosen equal to the ratio of the values of the output and the mafgsimal input voltages. The output is set (its generator 14 is connected to the first input of the first logic element 15 coincidence, the output of which is connected to the input of the first transistor switch 5

1. The output of the second logical logic 11 is connected to the input of the second transistor switch 16 and the first input of the logic element 15. The terminals of the second transistor switch 16 are connected to the auxiliary winding of the transformer 2. The output of the current sensor 9 is connected to the third input of the primary logic element 15 whose fourth input is connected to the output of comparator 10,

The converter works as follows,

In the transformer 2, with the transistor switch 1 open, during the time 0-t (FIG. 2), energy is accumulated from the primary constant-voltage source. After locking key 1 over time, the capacitor 8 is charged with current igt. In this case, the voltage Ug on the capacitor 8 increases much slower than the rate of decline of the current of transistor switch 1, which eliminates the energy loss during this process. After that, during the time t - t J, the accumulated energy is transferred to the load through diode 3 and capacitor 4. When current is terminated through diode 3, it is locked and recharging of capacitor 8 occurs due to the free oscillatory process in the circuit formed by this a capacitor and a transformer 2. The indicated process is carried out

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0

until time t |, corresponding to a zero voltage value on the windings of the transformer 2, which is detected by means of a voltage comparator 10. The signal at the output of this comparator triggers the duration modulator and unlocks through the logic element 1, the second transistor switch 16

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is zero and, consequently, the current in the oscillating circuit does not change. After a period of modulation t J determined by the voltage at the control input of the modulator 12, the signal at the output of the driver, the control of the pulses changes j, which causes locking of the key 16 and the progress of the reloading of the capacitor 8. When when the voltage on the capacitor 8 reaches zero, diode 7 is turned off, which leads to the termination of the current of the capacitor 8 (ig) i On the signal Ug from the current sensor of this

the capacitor at the output of the second logic element 15 a signal appears that unlocks the transistor switch 1. The transistor switch 1 is locked according to the signal and the master oscillator 14. Thus, in the converter all switching processes occur with virtually no energy loss at zero voltages on the switching elements, as a result of which the level of interference from the transducer is negligible. In addition, the frequency constant of the conversion ensures synchronized operation of the converter with the powered television equipment by applying horizontal sync pulses to the input of the master oscillator 14. At the same time, the transistor I is turned off during the damping horizontal pulse, which eliminates the influence of most significant, and increase the electromagnetic compatibility of the converter with the powered television equipment.

The use of a single-ended stabilized converter in the construction of sources of secondary power supply for studio television cameras, to which image requirements are particularly high, makes it possible to reduce their size and weight by eliminating noise suppressing filters for power supply purposes, as well as eliminating various types of power. shielding structures inside the camera In addition, when such studio television cameras work together with other television equipment, the application of the proposed It allows to exclude acoustic noise due to the beats of frequencies of transformations of various sources of secondary power supply by means of their synchronization.

Claims (1)

Invention Formula A single-ended stabilized constant-voltage-to-constant voltage converter containing series-connected and connected to The input pins are a transistor switch and the primary winding of the transformer, the secondary winding of which is connected to the capacitive filter and output pins through a one-half-cycle rectifier, a diode, a shunt transistor switch having a common output with a capacitor of the resonant circuit, developed by the specified capacitor and additional winding of the transformer. pulses, the input connected to the output of the feedback amplifier, the detector 5 voltage polarity, inputs connected in parallel to the auxiliary winding of the transformer, a current sensor connected to the common point of the auxiliary winding and an additional diode, another pin of which is connected to the common input of the converter, the outputs of the detector, the polarity of the voltage and the current sensor through the first the coincidence gate is connected to the control input of the transistor switch, and the number of turns of the secondary winding of the transferor, referred to the number of turns of the primary winding, is less than or equal to but Q is the ratio of the output and maximum input voltage values, characterized in that, in order to increase the electromagnetic compatibility with the powered television equipment by providing constant and synchronous conversion frequency, a master oscillator, the second transistor switch and the second logical element are entered into it No, the input is connected to the output of the driver control pulse, and the output is connected to the control input of the second transistor switch, the power terminals of which are connected to the outputs 5 of an additional winding of transformers, the master oscillator is connected to the first input of the first logic element, the second input of which is connected to the control input of the second transistor key, the output of the current sensor is connected to the third input of the second logic element, the fourth input of which is connected to the comparator output. five PHYO. I Editor L.Pcholinsk Compiled by N.Tsishevsk Tehred M. Khodanich Proofreader I. Muska Order 3975/53 Circulation 659 Subscription VN1ZhSh of the USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Rautska nab. 4/5 Production and printing company, Uzhgorod, st. Design, And