RU141793U1 - START-UP AND PROTECTION DEVICE FOR VOLTAGE CONVERTER - Google Patents

Abstract

A device for starting and protecting a voltage converter, comprising a PWM controller; a make-up circuit comprising a transformer-rectifier assembly comprising a secondary winding of a power transformer with a rectifier circuit connected to one terminal with a current return circuit, a second capacitor connected between the PWM controller power input and the current return circuit; a starting circuit connected between the positive bus of the IVE and the power input of the PWM controller, characterized in that the make-up circuit contains a choke connected by one terminal to the other terminal of the transformer-rectifier unit, a diode connected by an anode to another terminal of the choke, a zener diode connected by a cathode to the cathode of the first diode, and the anode to the power input of the PWM controller, a resistor and a first capacitor connected in parallel, connected between the common connection point of the inductor and diode and the current return circuit.

Description

Technical field

The utility model relates to electrical engineering and can be used in pulsed sources of secondary power supply (RES), operating at high reactive load at the output, as a start-up and protection circuit, namely for operation of the RES in "hiccup" mode.

State of the art

The IVE control circuits are usually performed on microcircuits, so their power is sometimes organized from an additional low-voltage rectifier with a separate low-power transformer, however, this increases the size and weight of the IVE.

The most widespread are the IVE, in which for the initial start-up of the control device, special “starting” power supply circuits are used. After the powerful conversion cascade has started, the power to the control device comes from one of the windings of the power pulse transformer or inductor, and the "start" circuit is turned off.

A device is known (patent US 5498995 "Short circuit frequency shift circuit for switching regulators", priority date 03/12/1996, IPC H02M 3/335, G05F 1/10), in which to filter the voltage that occurs on the recharge winding 42 of the transformer TR1 , an inductor L1 is used, which is included in the make-up winding circuit 42 of transformer TR1.

The disadvantages of this device include the fact that in the "Icahn" short-circuit at the output (CP _OUT) value L1 choke inductor does not provide protection from high voltage spikes occurring on the recharge coil and no separate adjustment is turned on the time on and time .

A device is known (patent US 5815383 "High voltage start-up circuit and method therefor", priority date 12/27/1996, IPC H02M 7/517, H02M 1/00), in which at the initial time, when the power is turned on, the generator current 10 produces the charge of the capacitor 50. Further, when the converter PWM 1 starts operating with 42, the current generator 10 is turned off and the capacitors 52 and 50 are charged through the secondary winding of the makeup 44A of the transformer 44 and diodes 46, 48.

The disadvantages of the device include the fact that in the "hiccup" mode with a short _{OUT there is} no protection against high voltage pulses in the secondary winding circuit 44A of the transformer 44.

This device is selected as a prototype.

Utility Model Essence

The technical result of the operation of IVE with a large reactive load at the output, which corresponds to a short circuit at the output at the initial start-up moment (short circuit _OUT ), is:

- providing independent adjustment of the on time and time in the on state of the module;

- protection of the PWM controller from high voltage voltage pulses arising on the feed winding of the transformer-rectifier unit.

This technical result is achieved due to the fact that the device for starting and protecting the voltage converter (Fig. 1) contains: a PWM controller 3; make-up circuit, including: transformer-rectifier unit 1, containing the secondary winding of the power transformer (T1) with a rectifier circuit, connected by one output to the current return circuit, a second capacitor (C2) connected between the power input of the PWM controller 3 and the current return circuit; a starting circuit 2, connected between the positive bus of the IVE and the power input of the PWM controller 3, and the make-up circuit contains a choke (L1) connected by one terminal to the other terminal of the transformer-rectifier node 1, a diode (VD1) connected by an anode to the other terminal of the inductor (L1 ), a zener diode (VD2) connected by a cathode to the cathode of the first diode (VD1), and by an anode to the power input of the PWM 3 controller, a resistor (R1) and a first capacitor (C1) connected in parallel between the common connection point of the inductor (L1) and the diode (VD1) and current return circuit.

In order to ensure the operation mode of the EVE in which a large reactive load is used, for example, a large capacitance or an electric motor, which is perceived by the IVE at initial start-up as a short-circuit at the output (Short-circuit _OUT ), the device switches to the "hiccup" mode, cyclic switching on to charge the reactive load turning off to cool the EVE.

Period "hiccupping" fault mode when _OUT is provided by using a capacitor in the PWM power supply controller circuit of sufficient capacity (C2 capacitor). However, in this case, directly opposite requirements appear. The start-up time of the RES in the initial start-up should be minimum and sufficient for cooling the RES in the "hiccup" mode with short circuit _OUT , and the time of the on-state of the RES in the "hiccup" mode with short circuit _OUT should be large and sufficient to charge the reactive load (large capacity or start-up) electric motor).

Another problem in the "hiccup" mode is the appearance of high-voltage surges that occur on the transformer-rectifier node, as a result of the short duration of the current pulses of the power transistor and the presence of the leakage inductance of the power transformer.

To solve these problems, it was proposed to separate the capacitor in the power circuit of the PWM controller using a diode. A capacitor is used for charging of the starting circuit, providing a small on-time at initial startup and sufficient for cooling IVE in "ikayuschem" fault mode when _OUT. Another capacitor is isolated from the starting circuit by a diode isolation and is charged from the transformer-rectifier unit. Its capacity provides, together with the first capacitor, the required on-time of the IVE in the "hiccuping" mode with a short _OUT . To protect against high-voltage surges on the transformer-rectifier unit, a protection inductor is connected between it and the diode, and a zener diode is activated between the PWM controller and the diode, limiting high-voltage surges.

The operation of the device is illustrated by the example of a variant of its execution (Fig. 2) and diagrams (Fig. 3, 4).

At the time of the initial switching on of the IVE (Fig. 3.), when the voltage + Uin is applied to the input of the IVE, the capacitor C2 starts charging (curve U _C2 ) using the starting circuit 2, for example, using a current generator. When the voltage on the capacitor C2 is sufficient to start the PWM 3 controller, the IVE converter starts working and the output voltage appears on its output. Simultaneously, the output transformer-rectifier unit 1 feeding voltage appears which charges the capacitor C1 and through the separating and zener diode VD1 VD2 capacitor C2 (curve U _C1C2) 3 and the PWM controller is powered from the circuit has transformer-rectifier unit 1.

When the short-circuit mode _OUTPUT occurs (Fig. 4), the duration of the output pulses of the PWM 3 controller decreases under the influence of information from the current sensor 4 and as soon as the energy of the current pulses in the make-up winding becomes insufficient for the capacitors C1 and C2 to fully charge, their gradual discharge begins (curve U _C1C2 ). When the supply voltage of the PWM controller 3 reaches a certain threshold value, it is turned off. The discharge time of the capacitors C1 and C2 determines the time in the on state of the module in the "hiccuping" mode at short circuit _OUT . High-voltage surges occurring at the output of the transformer-rectifier unit 1 are smoothed by the protection inductor L1 by capacitors C1 and cut off by the zener diode VD2.

After turning off the PWM controller 3, the capacitor C2 starts charging from the start-up network 2 (curve U _C2 ) and the cycle is repeated until the short circuit _OUTPUT disappears. This effect is due to the fact that the current consumption of the PWM 3 controller in the off state is several orders of magnitude less than the current consumption in the on state. The charge time of the capacitor C2 determines the turn-on time of the module at the initial start-up of the module and in the "hiccuping" mode at short circuit _OUT .

The advantage of this starting and protection device is that in the "hiccup" mode during short circuit _OUT, in addition to independently adjusting the on-time and the on-time of the module, a protection function against high-voltage voltage pulses arising on the transformer-rectifier unit is also provided.

Comparative analysis with the prototype shows that the claimed device differs in the totality of the claimed features from the prototype, and, therefore, the proposed technical solution has significant differences.

The proposed device is made of standard elements that are commercially available from industry. It is assembled by typical installation operations using standard equipment, which is especially important in serial production. Therefore, the proposed device meets the criterion of industrial applicability.

Claims (1)

A device for starting and protecting a voltage converter, comprising a PWM controller; a make-up circuit comprising a transformer-rectifier assembly comprising a secondary winding of a power transformer with a rectifier circuit connected to a current return circuit by a single output terminal, a second capacitor connected between the PWM controller power input and the current return circuit; a starting circuit connected between the positive bus of the IVE and the power input of the PWM controller, characterized in that the make-up circuit contains a choke connected by one terminal to the other terminal of the transformer-rectifier unit, a diode connected by an anode to another terminal of the choke, a zener diode connected by a cathode to the cathode of the first diode, and the anode to the power input of the PWM controller, a resistor and a first capacitor connected in parallel, connected between the common connection point of the inductor and diode and the current return circuit.

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