DE2360670C3 - Device for simultaneous ignition of a number of controllable semiconductor valves in a converter for high voltages - Google Patents

Description

3. Device according to claim 2, characterized in that the impedance element (/ 1) is controlled by a characteristic frequency oscillator (oil), the output signal of which is switched on or off as a function of the status signal (ui) , the feedback receiver (R) is matched to the characteristic frequency of the characteristic frequency oscillator (Oi).

4. Device according to claim 2, characterized by a capacitance diode as an impedance element.

5. Device according to claim 2, characterized by a PIN diode as an impedance element.

6. Device according to claim 1, characterized in that a voltage monitoring circuit (UX) is connected to its anode-cathode path to form the status signal (u 1) via the current-blocking or current-conducting state of the semiconductor valve (Vl).

7. Device according to claim 1, characterized by a circulator (Z) ah modulation-dependent signal switch.

8. Device according to claim 1, characterized in that the feedback receiver (R) is connected downstream of an evaluation circuit (W) for generating display signals (al, al) and / or alarm signals (w).

9. A device according to claim 1 having a radio frequency transmitter comprising a frequency generator for generating a carrier frequency and a bo further frequency generator for generating a sub-carrier; characterized contains frequency such that the carrier frequency (f / q) a phase modulator (M) is entered, the the carrier frequency is frequency-modulated as a function of the output signal of a modulo <■ <<, tors (Mi) and fed to a frequency multiplier (F) to form the transmission signal, the modulator (M 1) setting the subcarrier frequency (/ 1) with the control signal (s 1 ) amplitude modulated (Fig. 2).

10. Device according to claim 9 for a number of controllable Haibleiterveiitilen, characterized in that a separate subcarrier frequency (/ 1, f2) is provided for each semiconductor valve (Vl, V2), each via modulators (AfI ₁ Af 2) with the control signals (s 1, s 2) are amplitude-modulated and fed to a logic element (Q) whose sum signal in the phase modulator (M) frequency-modulates the carrier frequency (f / q).

11. Device according to claim 3 for a number of controllable semiconductor valves, characterized in that for each semiconductor valve (Vl, V2) its own high-frequency receiver (£ 1, £ 2) with an antenna (B1, 52) and an impedance element (/ 1, / 2) is provided with a characteristic frequency oscillator (0 1, O2) , the characteristic frequencies (n 1, π 2) being different from one another and the feedback receiver (R) either having a number of filters (N 1, N2) or a filter that can be sequentially tuned to the different characteristic frequencies.

The invention relates to a device for the simultaneous ignition of a number of controllable Semiconductor valves in a converter for high voltages with a high-frequency transmitter the control signals modulated transmission signal is generated and emitted via an antenna connected to it and the one assigned to the controllable semiconductor valves High-frequency receivers receive and demodulate the transmission signal via an upstream antenna and apply the demodulated control signal to the control path of the relevant semiconductor valve.

The transmission of control signals from a control signal generator to the control path of controllable Semiconductor valves will always be wireless, i.e. mi! galvanic isolation, made, if there is a particularly large difference in potential between the control signal transmitter and the semiconductor valves, if there is a particularly large distance between them or if both are difficult to access.

In the case of the device known from CH-PS 4 13 993 mentioned at the outset, the Control signals used a frequency of about 1 MHz. This high frequency is associated with a center frequency modulated, the receiver designed as demodulators using the modulation frequency as the control frequency to a switching device that generates ignition pulses for the controlled valves.

In such a device it is of interest whether a controllable semiconductor valve is operated Short circuit has occurred in the anode-cathode path. Are there several controllable semiconductor valves in summarized in a converter, one also wants to find out how many and which semiconductor valves have failed are.

In a known arrangement for detecting the lack of power in a Stromriehtervent.ls the Reverse voltage of the converter valve evaluated (DT-OS 21 00 776). One in parallel with the converter valve switched light-emitting element detects the reverse voltage of the converter valve, converts it into converts a light signal and transmits it via a

Light path to a photoelectric converter that is on its output emits a signal when the converter valve is de-energized for the transmission of the Status signal, a separate transmission link with transmitter and receiver is required.

In a known tax rate for the delivery of width-limited ignition pulses in a converter with one or more controllable converter valves is a circuit for monitoring the to the Converter valves provided voltage (DT-OS 23 02 227). This circuit gives an output signal when a blocking voltage is applied to the converter valves. A switching device there a width-limited ignition pulse to the controllable converter valves if there is an output signal at the same time pending, which indicates blocking voltage, and when a pulse from a pulse generator is pending. One Transmission of the status signal is not provided in this known tax rate.

The present invention is based on the object in a circuit arrangement of the initially mentioned type to ensure that a feedback about the failure of one or, if necessary, several Semiconductor valves with little circuitry effort is made possible.

This object is achieved according to the invention in that each antenna of the high-frequency receiver a controllable reflective modulation element is connected downstream, depending on one of the current-blocking or the current-conducting state of the semiconductor valve characterizing state signal part of the received St-ndesignals re-modulien and reflected as a feedback signal via the antenna, and that the antenna of the radio frequency transmitter a modulation-dependent signal switch is connected downstream, which the feedback signal to a feedback receiver feeds.

In the device according to the invention, the high-frequency receiver on the semiconductor valve has a controllable reflective modulation element is provided, depending on a status signal via the current-blocking or current-conducting state of the valve part of the received high-frequency energy newly modulated and reflected as a feedback signal. This creates its own transmitter to broadcast the Feedback signal and a separate receiver to receive it saved. The feedback signal is rather emitted via the antenna of the radio frequency receiver and from the antenna of the radio frequency transmitter caught. Such a double use of antennas is for example from the FR-PS 13 58 780 known. To the antenna of the radio frequency transmitter a modulation-dependent signal switch is connected, which sends the feedback signal to a feedback receiver feeds.

A preferred development of the invention provides that an impedance element is used as the controllable reflective modulation element, its impedance is controlled as a function of the status signal. Here, the one used for the control is used on the Receiving antenna of the receiver partially reflects incoming high-frequency power on the impedance element and used for wireless transmission of the feedback. A capacitance diode can be used as the impedance element or a PIN diode (semiconductor data book 1972/1973, standard types, Siemens Aktiengesellschaft, Page 512) can be used.

In the mentioned development of the invention can

50

(", The impedance term of a characteristic frequency oscillator be controlled, the output signal of which is switched on or off as a function of the status signal, wherein the feedback receiver is matched to the characteristic frequency of the characteristic frequency oscillator provided that, for reasons of interference immunity, a frequency modulation of the high-frequency transmitter and an amplification controllability of the characteristic frequency oscillator The characteristic frequency oscillator controls the impedance element with its characteristic frequency with regard to its impedance and thereby causes an amplitude modulation of the reflected and as feedback signal utilized part of the received high frequency energy.

To generate a status signal via the current blocking or the current-conducting state of the semiconductor valve can be connected to a voltage monitoring circuit whose anode-cathode path must be connected. Such a voltage monitoring circuit can, for example make use of a principle as it is in the already mentioned DT-OS 21 00 7/6 or the DT-OS 23 02 227 is known.

A circulator can preferably be used as the modulation-dependent signal switch. A Circulator is a waveguide component, which is described, for example, in Collin »Fundamentals of Microwave Technology«, VEB Verlag Technik Berlin, 1973, page 334 is described.

It is particularly important to have a sharp separation in the transmitting part of the transmitted by the transmitting antenna To carry out the transmission signal from the feedback signal picked up by the same transmitting antenna. this is preferably achieved through different types of modulation. If the transmission signal is frequency modulated, then the reflected feedback signal should be amplitude modulated.

If there is a large number of semiconductor valves, the control signals should be transmitted using different Subcarrier frequencies take place.

Embodiments of the invention and their advantageous characterized in the subclaims Refinements are explained in more detail below with reference to the figures. For same or equal Acting components are used the same reference numerals. Show it:

F i g. 1 shows a circuit arrangement for the wireless transmission of two control signals with wireless Transmission of feedback signals,

Fi g. 2 an embodiment of the control transmitter used for this,

F i g. 3 shows an embodiment of the receiver used therein and

Fi g. 4 shows an embodiment of a combination of the feedback and feedback circuit used in this case.

According to the schematic representation in FIG. 1, a control transmitter S is provided, to which a control signal s i for igniting a semiconductor valve Vi, in particular a thyristor, is specified via an input terminal. Instead of this one semiconductor valve Vi , a plurality of semiconductor valves connected in series or parallel to one another, which are to be ignited at the same time, can also be provided here. A further control signal s2, which is used to ignite a further semiconductor valve V2 or a group of such semiconductor valves, is specified for the control transmitter S via a further input terminal.

In Fig. 1 are different from the normal case only

two semiconductor valves VI ₁ V 2 are shown. It is assumed that both semiconductor valves Vl ₁ V2 the same converter for high voltage, z. B. the same converter for high-voltage direct current transmission, but that they are arranged in different branches and should be ignited at different ignition times.

The control transmitter S emits a transmission signal ρ to a transmission antenna A via a circulator Zein. The frequency of this transmission signal ρ is, for example, in the GHz range. The transmission signal ρ reaches a number of receiving antennas B 1, B2, ..., of which only the two receiving antennas B1, B2 are shown. The wireless transmission of the transmission signal ρ is indicated by the wavy arrows in FIG. 1 indicated. The receiving antennas B 1, B 2 are set up at some distance from the transmitting antenna A. The minimum distance is generally determined by the safety distance which must be maintained by the semiconductor valves at the highest voltage of the converter. In Fig. 1 only two receiving antennas B 1 and B2 are shown. In general, such a receiving antenna B 1, B 2 will be assigned to each of the existing semiconductor valves V1, V2.

Each receiving antenna Bi, B2 , together with a receiver Ei, E2, which each contains a demodulator, is assigned to one of the semiconductor valves V1, V2 of the converter. The individual receivers Ei, E2 have largely the same structure. They have the property that they select the control signal 51 or s 2 assigned to them from a large number of available control signals and, depending on this control signal 51, s 2 , send an ignition signal to the control path of the semiconductor valve V1 or V2.

A controllable impedance element / 1 or / 2 is arranged between the receiving antenna B1, B 2 and the receiver Ei, E2. A capacitance diode or a PIN diode can each be provided as the impedance element Ii, 12. Its impedance can each be controlled by a characteristic frequency oscillator ΟΙ, Ο2 with a characteristic frequency π 1 or η 2. The characteristic frequencies nl, π 2 emitted by the characteristic frequency oscillators Oi, O2 are a characteristic of the relevant semiconductor valve V1 and V2. The characteristic frequency π 1 is therefore assigned to the semiconductor valve V ί and the characteristic frequency π 2 is assigned to the semiconductor valve V2. The individual characteristic frequencies nl, η 2 of all semiconductor valves V1, V2, .. are different from one another and can, for. B. are each 1 kHz apart.

The transmitted signal ρ picked up by the receiving antenna Bl, B 2 reaches the receiver Et, E2 via the impedance element 11, 12 and is demodulated here. In this case, it is determined whether the demodulated signal for the ignition of the respective valve Vl and V2 is actually provided If so, the demodulated signal is used for firing the semiconductor valve Vl or V2.

The characteristic frequency oscillators Oi, O 2 are provided for reporting information about the state of the relevant semiconductor valve Vl or V 2. In order to determine the state of the semiconductor valves Vl, V2, voltage monitoring circuits Ui, i / 2 are provided in particular, which monitor the anode-cathode voltages, & h. Measure the voltages at the anode-cathode sections of the semiconductor valves Vl and V2. If the anode-cathode voltage is zero, if there is a fault, the voltage monitoring circuit U1, LJ2 emits a blocking signal to the characteristic frequency oscillator 01 or O 2 as output signal u 1 or u2. This blocking signal ul, u2 blocks the output voltage of the characteristic frequency oscillator Oi, O 2, ie makes this output voltage zero.

In the undisturbed case, when a blocking voltage is applied to the semiconductor filaments Vl, V2, each voltage monitoring circuit U 1, t / 2 does not emit a blocking signal. The characteristic frequency oscillators Oi, O2

ίο then change the value of the associated impedance element / 1, / 2 in accordance with the characteristic frequency η 1, η 2. The incoming transmission signal ρ is thereby modulated. This modulation has the effect that the transmission signal ρ is partially reflected at the controllable impedance 11, 12

is and is emitted again via the receiving antenna B1, B2 as an amplitude-modulated feedback signal r 1, r2. Part of the radiated power is returned to the transmitting antenna A via the transmission path.

The mixture of feedback signals r 1, r 2 received by the transmitting antenna A is passed to a feedback receiver R via the circulator ZaIs received signal. This feedback receiver R selects the reflected feedback signals rl, r2 modulated by all receiving antennas Bl, B 2 according to their characteristic frequencies π 1, η2 ... If one of the semiconductor valves Vl, V2 is disturbed, the corresponding characteristic frequency nl or π2 is missing in the received signal e. An evaluation circuit W processes the signals emitted by the feedback receiver R , so that information about the code number, location and / or number of the faulty semiconductor valves V1, V2 is obtained. The evaluation circuit W emits display signals a1 and a 2 assigned to the valves V1, V2 at its output terminals, which signals can be used to operate control lamps. The evaluation circuit W also emits a sum signal w which can be used to trigger an alarm.

Various measures must be taken so that the transmission signal ρ and the mixture of back-emitted feedback signals r 1, r 2 do not influence one another. First of all, different types of modulation should be provided. For example, the transmission signal ρ can be frequency-modulated in time with the control signals Ie si, s2 and the received signal e, as already mentioned, can be amplitude-modulated. However, one can also proceed in reverse: the transmission signal ρ can be amplitude-modulated and the reception signal e can be frequency-modulated.

The first-mentioned solution is, however, the more favorable one, because a frequency-modulated transmission signal ρ is less susceptible to interference that can be caused, for example, by glow discharges on the converter. A frequency-modulated transmission signal ρ

is simpler and less susceptible to interference on the valve side process.

The separation of the transmitted signal ρ and the received signal e by means of the circulator Z should be mentioned as a further measure. Instead of a circulator Z, any other common signal splitter can be used. And as a third measure, care should be taken to ensure that different frequencies for the characteristic frequencies ni, nl on the one hand and - with frequency modulation of the transmission signal ρ - for the

Modulation frequencies in the exciter S can be used.

In Fig. 2 is an exemplary embodiment of the control transmitter S shown

t> U OYU

It is assumed that the semiconductor valves to be ignited are arranged in a converter in a three-phase bridge circuit. A control signal generator, not shown, which z. B. is part of a control loop, outputs control signals 51,5 2, ..., s 6, which are to be used to ignite the semiconductor valves in the six branches of the converter. the

The frequency of these control signals is si, s2 s6

z. B. 50 Hz.

According to Fig. 2, the control transmitter 5 contains a ι ο frequency generator G 1, ζ. Β. a quartz oscillator that emits a signal with a frequency f \. This frequency ft is constant. For example, it should be in the range from 6.7 to 11 MHz. This frequency f \ is referred to as sub-carrier frequency f \ designated net is. The signal emitted by the frequency generator G 1 is fed to a modulator M 1, which is provided for amplitude modulation. For example, an electronic switch, for example a switching transistor, can be provided as the modulator AiI. Di m modulation input M1, e.g. B. the base of the switching transistor, the control signal 51 is supplied. This control signal s 1 is provided for simultaneous ignition of all semiconductor valves Vl of a branch of the converter. The signal emitted by the modulator Mi is a signal of the subcarrier frequency ft, which occurs in the cycle of the control signal s 1, ie z. B. with 50 Hz, is amplitude modulated.

The further control signals 5 2 to s6 are provided for the ignition of the semiconductor valves in the five other branches of the converter. A frequency generator-modulator combination is provided for each of these control signals ί 2 to 5 6. The control signal s2 is given, for example, to the modulation input of a modulator M 2 , to which a signal of the subcarrier frequency / 2 is applied by a frequency generator G 2. The individual frequency generators G \, G2 ... have different subcarrier frequencies ft, / '2, ... the output voltages of all the modulators M 1, M 2 ... are combined, ie added. For this, a logic element Q is provided for. B. can be designed as a resistor. The output voltages combined in logic element Q are fed to a phase modulator M.

The phase modulator M is preceded by a carrier generator G , which can be designed as a quartz oscillator and, for example, emits a carrier signal with a constant frequency f / q of 51 MHz. The carrier signal emitted by the carrier generator G is frequency-modulated in the phase modulator M by the sum signal of the logic element Q applied to its modulation input. The frequency-modulated Ausgangssignai M of the phase modulator is a frequency multiplier F fed This frequency multiplier may F z. B. have a multiplication factor of 9 = 48. The frequency of the carrier generator f / q is increased by the factor q to the frequency value /. At the output of the frequency multiplier F , a signal appears that has a carrier frequency / of 2448MHz, for example.This signal is amplified by a power amplifier L to the required output power , which can be 2W, for example. The output signal of the power amplifier L is already the transmission signal p. According to FIG. 1, it is passed to the transmitting antenna A via the 6s circulator Z. The transmitted signal ρ transmitted by the transmitting antenna A thus has a carrier frequency / of 2.448 GHz. This carrier frequency / lies in the so-called international industrial band. Deviating from this, any other frequency above 300 MH2 can be used as the carrier frequency f.

In summary, the following can be said about the control transmitter 5: A carrier signal with a carrier frequency f is used, onto which six subcarrier signals are modulated by frequency modulation. In the frequency diagram, the subcarrier signals each result in six subcarriers located above and / or below the carrier frequency f . These sub-subscriptions can in particular each have the same frequency spacing from one another. The sub-carrier frequencies / 1, / 2 ... can be derived from the output frequencies? a single frequency generator that uses G 1, G 2, ... instead of the individual frequency generators! will derive. On each of the six sub-carrier signals, in turn, one of the six control signals, which have a low frequency of e.g. B. have only 50 Hz, modulated by amplitude modulation.

In the following, an embodiment of one of the receivers E1, E2 shown in FIG. 1 is described in more detail with reference to FIG. These receivers £ 1, El show substantially all of the same construction, so that it is sufficient to consider in more detail the receiver E1.

According to FIG. 3, the transmission signal ρ picked up by the receiving antenna E 1 reaches the receiver Et via the controllable impedance element / 1. Here it hits a ratio detector or generally detector D 1, which acts as a frequency demodulator. It is provided for demodulating the carrier frequency /. The output signal of the detector D 1 is fed to a filter H 1 which is tuned to the subcarrier frequency / 1. The frequency to which the filter Ht is tuned depends on the selected branch of the converter. The corresponding filter in the receiver E 2 is thus matched to the subcarrier frequency / 2. The filter Ht thus only lets through a signal when the corresponding control signal 51 is not equal to zero and thus indicates the ignition of the semiconductor valve VI as desired.

The filter H 1 is followed by an amplifier X t. Its output signal, which is still amplitude-modulated at the rate of the control signal s 1, is sent to an amplitude demodulator Pi . This amplitude demodulator Pt, which provides amplitude demodulation, is followed by a flip-flop K t, in particular a Schmitt trigger. This flip-flop K 1 ensures the formation of rectangular ignition pulses for the semiconductor valve Vl. The output side of the flip-flop Ki is connected to the control path of the semiconductor valve Vl. The temporal course of the an da; The ignition pulses emitted by the semiconductor valve Vl corresponds to the profile of the control signal s 1.

The receiver £ 2, which is associated with the semiconductor valve Vi is, accordingly be formed Filtei is - as already mentioned - adapted to the subcarrier frequency / ° 2 emitted by him ignition pulses for firing the semiconductor valve Vi thus correspond in their time characteristic to · the course of the Control signal s 2.

In a practical embodiment, in which the output power radiated by the transmitting antenna A is about 2 W, an input power of 2 mW was obtained at the receiving antenna B 1, which was set up at a distance of about 5 m. AU transmitting antenna A for the carrier frequency before / = 2.448 GHz was a parabolic reflector mil

703 611/30

M- · ^ \ j yj \ j I \ J

a diameter of 2 m has been used. Since the received input power was relatively high, an input gain in the receiver Ei was not necessary. A high-pass filter was used as the filter Hi , so that low-frequency interference could be effectively eliminated.

In Fig. 4 shows an embodiment of a combination RW of a feedback receiver R and an evaluation circuit ^.

According to FIG. 4, the received signal e, which consists of a mixture of the two feedback signals rl and rl , is initially fed to an amplitude demodulator P. If one of the semiconductor valves Vi and V2, for example the semiconductor valve Vl, is defective, the associated feedback signal is missing, e.g. B. the feedback signal rl. After the amplitude demodulation in the amplitude demodulator P , the received signal e is fed to two different filters N 1 and N 2. Each of these two filters Ni and N 2, which can only have a small bandwidth, is matched to one of the characteristic frequencies η 1 or η 2. This means that only identification signals with the relevant identification frequency are allowed through. These signals are fed separately to amplifiers Yi and Y2 , each of which has a trigger stage Ti or 72, e.g. B. Schmitt trigger, is connected downstream. These flip-flops Ti, T2 are used to form display signals a 1, a 2, which can be used to feed control lamps. The two display signals a1 and a2 are also fed to an OR element O , the output signal of which can be used to trigger an alarm. This output signal w can also be used to trigger protective measures for the semiconductor valves V1, V2, for the disturbed branch or for the entire converter.

Notwithstanding the representation in Fig. 1, the converter can, for. B. contain a total of 1000 semiconductor valves. Thus, a total of 1000 feedback signals rl, / 2,..., RHDOO with the characteristic frequencies η 1, η 2 η 1000 can be contained in the received signal. for

In this case, a total of 1000 filters Nt, Λ / 2, ... / VIOOO with a low bandwidth connected in parallel on the input side are to be provided. These are then each matched to one of the characteristic frequencies ni, n2, ..., n 1000. The frequency spacing of these filters Ni, N2 N 1000 can

is z. B. progressively be 100 Hz, with the frequency 1.1 MHz can be provided as the characteristic frequency / 1, for example. The feedback receiver R then acts selectively because of the built-in filter. Overall, it can be viewed as an interrogation device that provides information on the state of a semiconductor valve, which is generally difficult to access.

You can save the large number of filters Ni, N2, ... if you use a single filter and its frequency, z. B. starting from the frequency 1.1 MHz, when queried step by step, z. EJ. each tuned by 100 Hz. The use of a filter with a step-wise variable frequency is more cost-effective when operating a converter with a large number of semiconductor valves than the parallel use of a large number of filters with a fixed frequency.

1 sheet of drawings

Claims (2)

Patent claims: 1. Device for the simultaneous ignition of a number of controllable semiconductor valves in a converter for high voltages, in which a high-frequency transmitter generates a transmission signal modulated with the control signals and emits it via an antenna connected to it and in which the high-frequency receiver assigned to the controllable semiconductor valves transmits the transmission signal receive and demodulate an upstream antenna and transmit the demodulated control signal to the control path of the relevant semiconductor valve, characterized in that the antenna (BX) of the high-frequency receiver (£ "1) is followed by a controllable reflective modulation element (/ 1) which is dependent on a state signal (u 1) characterizing the current-blocking or current-conducting state of the semiconductor valve (Vl), a part of the received transmission signal is newly modulated and reflected as a feedback signal (rl) via the antenna (Bi) , and that the antenna (A) of the high frequency transmitter (S) is followed by a modulation-dependent signal switch (/.) . which sends the RüVkmcldcsign.il (/ · 1) to a feedback receiver (R) . 2. Device according to claim 1, characterized by an impedance element (/ 1) as a controllable reflective modulation element, the impedance of which is controlled as a function of the state signal (u I)