SU1582267A1 - Transistor converter with protection - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase the reliability of a transistor converter with protection. The impulse from the start-up unit 8 opens the transistor 3, and the supply voltage flows through the current sensor 11 to the generator 4, which through the amplifier 7 drives the inverter 1. On the base of the transistor 3, a triangular voltage is formed with a constant component that compares with a voltage drop across the current sensor 11 of the inverter. When the voltage across the sensor 11 of the base voltage of the transistor 3 is exceeded, it closes and disconnects the control unit 2 from the power source. Any fault in the protection unit causes the inverter to turn off, which increases the reliability of the device. 2 Il.

Description

The invention relates to electrical engineering and can be used to protect converters, for example, to power fixtures of highly mechanized faces ..

The purpose of the invention is to increase the reliability of a transistor converter with protection.

In FIG. 1 shows a diagram of a transistor converter with protection; FIG. 2 is a timing diagram explaining its operation.

The converter, (Fig. 1) contains an inverter 1, a control unit 2 connected through a transistor 3 to a power source "

The control unit 2 contains a pulse generator 4 on the comparator 5, one of the inputs of which is connected to a timing capacitor 6. The output of the comparator is connected to a power amplifier 7 with a transformer output.

The start-up block 8 contains a similar pulse generator 9 on a comparator * torus with a timing capacitor 10.

The emitter of transistor 3. and inverter 1 are connected to the power source through the sensor 11 of the output current of inverter 1, and the base of transistor 3 is connected .. through a capacitor 12 to the output of the trigger unit 8 and through a resistor 13 ~ to the output of an additional power amplifier 14 on one transistor 15, for example, a p-p-p type, the input of which is connected to the input of the comparator 5, connected to a timing capacitor 6 in the pulse generator 4 of the control unit 2.

The device operates as follows.

When the supply voltage is turned on, the transistor 3 is closed, since the capacitor 6 does not have a charge circuit and plus the power supply of blocks 2, 14 and 8 through the resistor 16 of the pulse generator 4 it enters the base of the transistor 15 and holds it closed, which also holds it closed and transistor 3.

To start the circuit, use the 8 ”launcher

Periodically repeating triggering pulses U _{3c (n} (Fig. 2), the duty cycle of which is determined by the timing capacitor 10, and the duration of the capacitor 12, arrive at the base of the transistor 3 and open it. The duration of the triggering pulses should be slightly longer than the switching on time of the transistors 3 and 15, so that provide reliable start.

During the open state of transistor 3, control unit 2 is connected to a power source through transistor 3 and inverter 1 output current sensor 11. The capacitor 6 of the pulse generator 4 of control unit 2 is initially discharged, and transistor 15 of additional power amplifier 14 is completely open, holding · in the 'open state and the transistor 3 after the expiration of the''Start _Pulse U _3an .

2Q, Pulse generator 4 starts working, t, e. capacitor 6 ,. periodically charging and discharging, forms rectangular pulses U ₁ at the output of the co-comparator 5 _;

The discharge of the capacitor 6 does not occur to zero, but to a certain voltage level, which is carried out by the appropriate choice of resistors in the pulse generator 4, i.e. according to the corresponding Q thresholds for the operation of the comparator 5. Thus, triangular pulses U ₂ are formed on the capacitor 6 (Fig. 2).

Pulses U2 are fed to the input of an additional power amplifier

14 are amplified and inverted in phase. The amplified pulses .U ₅ 'through the resistor 13 are fed to the base of the transistor 3.

₄ 0 Since the triangular pulses U ₃ are superimposed on the DC voltage component U _П0Сг , the transistor 3 is constantly open, the generator 4 generates rectangular pulses U ,, amplified by a power amplifier 7 with a transformer, from the secondary winding of which the pulses and 'enter - in inverter 1. If overload or short circuit in the output circuit

There is no 5Q inverter, then with normal operation. to the bot on the current sensor 11, current pulses U _{4 are formed} (in Fig. 2 for the inductive nature of the load), the amplitude does not exceed the constant voltage component U _noCT and does not affect the open state of the transistor 3 ·

In an emergency, i.e. with a significant increase in voltage

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inverter power supply, with through current of the inverter or during overload in the output circuit of the inverter, i.e. in any case, the excess of the voltage pulses Uj at the current sensor 11 is higher than the amplitude of the triangular pulses and _e , the transistor 3 closes and turns off the control unit 2 of the inverter 1, the pulses U ₇ do not enter the inverter, so the inverter also turns off "

The restart is carried out by the nearest start pulse, and if there is no overload or short circuit, the device starts to function normally. If overload or short circuit in the output circuit of inverter 1 is not eliminated, then the converter operates in the mode of start pulses, the duty cycle of which is relatively large and the duration of the emergency mode is not limited, since the inverter current in this mode is very small.

Claims (2)

Claim A transistor converter with protection, containing an inverter connected to a control unit, the first power terminal of which is connected to a positive input terminal, and the second power terminal is connected to the collector of the first transistor, a current sensor 5, a triggering unit made in the form of a pulse generator and connected to the input terminals , a second transistor, first and second resistors, characterized in that, 10 in order to increase reliability, a third resistor and capacitor are introduced, the control unit being made in the form of a power amplifier, the input to 15 through a matching resistor, 15 is connected to the output of the pulse generator on the comparator, the first input of which is connected through a timing capacitor to the second power output of the control unit, the emitter of the second transistor is connected to the positive input output through the first resistor, the base is connected to the first input of the comparator, the collector is connected through the second resistor connected to the base of the first transistor connected via a capacitor to the output of the trigger unit, and the collector through the third resistor is connected to the negative input terminal, connected through a current sensor to the emitter of the first transistor, while the current sensor is connected in series to the power supply circuit of the inverter. FIG. 2 t