DE3011540C2 - Arrangement for an inverter externally controlled via a control and regulation part - Google Patents

Description

The invention relates to an arrangement for an externally guided via a control and regulating part Inverter as defined in more detail in the preamble of claim 1.

It is the same for a rectifier with a transistor inverter in push-pull mode known, with alternately controllable transistors, the primary winding of an inverter transformer to be connected to a DC operating voltage in different directions, with secondary windings of the inverter transformer, different AC voltages can be tapped (e.g. DE-PS 12 44 281). It is rectified there in an unregulated manner and a special starter circuit ensures that the Inverter. In the event of a short circuit, the inverter stops oscillating and after a certain amount of time it will / oil aiiioniiiiisch restarted. That means that at a milk error is constantly switched to a possibly persistent short circuit, which leads to destruction

of the device

The object of the invention is for an arrangement with an external inverter of the special type mentioned above via a control and regulation part in addition to the constant relevance to further reduce the power loss, in particular the device itself protect by no in the event of a fault (no oscillation) or if the control system is switched off new unintentional start can occur.

This object is achieved according to the characterizing features of claim 1. Further advantageous embodiments of the invention can be found in the subclaims.
Although it is already known for switched-mode power supplies to increase the efficiency of an additional transformer for generating the control power of the output stages and to gain the supply voltage of the driver stages from the output power of the output stage (DE-OS 27 49 337). Elsewhere, a start-up supply from a mains voltage is already implemented for switched-mode power supplies (DE book: Wüstenhube: "Schaltnetzteile", Expert-Verlag 1979, p. 377 ff) Converter itself is effected. However, there are no other similarities, and in particular there is no self-protection against self-destruction, as it is formulated according to the task.

The invention eliminates the power loss completely and only in continuous operation of the inverter The starting processes result in negligible losses for a short time. In the event of a mistake! or in the event of a shutdown the controller cannot start again unintentionally.

The invention will be explained in more detail below on the basis of a schematic exemplary embodiment. Reference is made to the drawing, which shows the circuit of a front-controlled transistor inverter 1 (framed by dashed lines) with a control and regulation part 2 for pulse width regulation. The starting circuit 3 according to the invention is also framed by a dashed line.The inverter 1 consists of two alternately switching power transistors 4 and 5, which supply an unstabilized DC operating voltage Un (here e.g. 110 V =) with alternating polarity to the terminals 6 and 7 Lay the primary winding 8 of the inverter transformer. With 9, 10, 11, 12, 13 secondary windings are designated, from which - if necessary after appropriate rectification and sieving - stabilized voltages, some of different voltage levels, are to be taken. The secondary winding 9 is led via a rectifier 14 to the connections a and b of the control part 2 and is used in addition to the voltage self-supply with z. B. 15 V direct voltage simultaneously as a common actual value variable for all voltages to be stabilized in the windings 9-13. By means of an IC circuit internal to the control part 2, the two power transistors 4 and 5 are controlled via the connections /, g, h, ι in the sense of a pulse width control. Via a current converter 15 and a rectifier 16, an actual value proportional to the load current in the inverter I is fed to the control and regulating part 2 (connections c, d). With 17 and 18, 2 free-wheeling diodes and 19 and 20 filter capacitors with parallel resistors 21, 22 are also designated.

Since the inverter 1 is controlled externally via the regulating and control part 2, its power supply

is in turn dependent on the inverter 1, the inverter 1 cannot be started without outside help. This can be done simply by applying an external voltage and is usually with the DC operating voltage Us, which must be divided down to the supply voltage level for the control and regulation part 2, performed by wiid the DC operating voltage Un briefly via a series resistor 23 is reduced and the a Z- Diode 24 and a capacitor 25 stabilized voltage value applied to the connection of the control and regulating part 2 as a starting aid. The contact piece 26 'of the relay 26, which interrupts the starting aid after a time delay, is also connected. The starting state must last at least 4-6 seconds until the inverter 1 swings properly and can take over the self-sufficiency of its control and regulating circuit 2. For the inverter control z. B. a current of approx. 0.8-1 A is required. The time delay is achieved by charging a capacitor 27 connected to the DC operating voltage Un , whereby the charging takes place via a charging resistor 28 and the coil of the relay 26. If the capacitor voltage has the threshold voltage of a trigger diode 29, it switches through a thyristor 30, whereby relay 26 is connected to the DC operating voltage Un and the relay picks up.It thus separates the supply voltage from the control and regulation part 2 via its opening contact piece 26 'and also switches the stabilizing elements 24 and 25 away. In the meantime, the internal supply of the control and regulating part 2 via the winding 9 has started to overlap

A parallel resistor is also shown in dashed lines in the circuit 31 indicated This is only necessary in those cases where the relay 26 used alone is not the one for a selected thyristor type 30 provides required holding current.

1 sheet of drawings

40

45

50

55

60

Claims (4)

Patent claims: 1. Arrangement for an inverter externally guided via a control and regulating part, in which alternately connected transistors connect the primary winding of an inverter transformer in different sense of direction to an operating direct voltage and in which alternating voltages different from secondary windings of the inverter transformer can be tapped, characterized in that the inverter (1 ) is supplied in a known manner via a secondary winding (9) of the inverter transformer itself and is provided with a starting circuit (3) running via a relay (26), the starting circuit (3) controlling and regulating part (2) when a switch-on command is given. , irrespective of the actual build-up, £ j> of the inverter (1), applies only once for the limited time of a normal start using a delay element (27) to the operating DC voltage (Un) feeding the inverter and then switches it off non-destructively 2. Arrangement according to claim 1, characterized in that the DC operating voltage (Un) on the one hand (+, terminal 6) is reduced to the supply level via a series resistor (23) and applied to the control and regulating part (2, terminal e) and on the other hand via a thyristor (30) feeds a relay (26) whose contact piece (26 ') is arranged as an opener in the current path between the series resistor (23) and the control and regulation part (2) 3. Arrangement according to claims 1 to 2, characterized in that cL-m thyristor (30) a The center tap of the RC element (28, 27) is connected in parallel connected to the control electrode of the thyristor (30) via a trigger diode (29) is. 4. Arrangement according to claims 1 to 3, characterized in that to stabilize the supply voltage behind the contact piece (26 ') of the relay (26) via a Zener diode (24) with a parallel connected capacitor (25) a cross connection to the other pole (-, Terminal 7) of the DC operating voltage (Un) is provided.