WO1997023031A2

WO1997023031A2 - Device for high-voltage transformation by cascading

Info

Publication number: WO1997023031A2
Application number: PCT/DE1996/002407
Authority: WO
Inventors: Gernot Sikora
Original assignee: Studlar-Sikora, Jana
Priority date: 1995-12-18
Filing date: 1996-12-15
Publication date: 1997-06-26
Also published as: DE19547064A1; AU1921197A; WO1997023031A3

Abstract

The process for high-voltage transformation is based on the following steps: dividing the high voltage into any number of partial voltages in a divider cascade in which each divider consists of the parallel connection of an active and a passive component; shaping the partial voltages into adjustable a.c. voltages in the medium-frequency range; transforming the a.c. voltages in a complex transformer system consisting of a number of partial transformers corresponding to that of the partial voltages and combining the transformed partial voltages into an overall voltage, modifying the architecture of power components, e.g. transformers, to produce physical properties and achieve transmission properties which are prerequisites fo the proper operation of the process; fitting with a control, safety and monitoring electronic system for the transmission properties of the entire system and the partial systems with regard to the static and dynamic operating states and the dynamic transition states.

Description

Device for high-voltage conversion by cascading.

Description.

The invention relates to a device for converting an unregulated, strongly fluctuating high voltage into a regulated output voltage with potential isolation. In high-voltage conversion, circuit arrangements are known in which, by series connection (cascading) of thyristors, transistors or related semiconductors with a lower operating voltage than the supply voltage, are used as high-voltage switches. When semiconductors are connected in series, the

Transition states between "conductive" and "blocking" state, due to the specimen scattering very difficult to control. The amount of the total voltage divided into equal partial voltages on the semiconductors in the cascade is no longer guaranteed, which has consequences for operational reliability. The control of such components in the cascade is also not without problems, which can be seen from the large number of applications in this area. The following prior art documents were used for comparison purposes.

US 40 62 057 (Regulated Power Supply having a Series Arrangement of Inverters.

JP 07 - 31144 (A) and Abstr. 7031144 (DC j DC converter).

UNITRODE "Application Handbook 1987-1988 page 148 - page 156. P 40 22 176.8" Modulator for controlling high-voltage transistors ".

P 40 22 243.8 "disc transformer". The system described in US Pat. No. 4,062,057 is completely unsuitable for use with the object of the invention for the following reasons and also deviates considerably in essential points:

1. Each inverter in the cascade has its own transformer in the output. 2. Due to the design of the transformers (power and driver transformers), the system is not suitable for the frequency range of 20kHz and more, nor for the voltage range of 3kV and more.

3. In the system, the critical transition states when switching the inverters at higher frequencies are not taken into account, which leads to the uneven distribution of the voltages at the individual inverters.

It is admitted and accepted as a fact, but is to be compensated for by the so-called "SELF BALANCING effect) by the parallel connection of the power transformers at the output, which is no longer possible in the frequency range of 20 kHz. In contrast to a self-regulation in question, in the device according to the invention Additional circuit measures enforce the uniform voltage distribution in the cascade. In Japan Patent JP 07 0331144A there is a cascading of converters, but it is a completely different task. The design of the transformers is intended to superimpose an impulse voltage on the direct voltage The help of which is to minimize the interval between the states of the energy supply from the voltage source through the switching stages ("on time") and the switch - off times "off - time" enforced by pulse width modulation, in order to achieve the cleanest possible direct voltage without to get additional filtering. The power transformer has a center tap, although it is fed from a bridge.

The circuit breaker types used according to the prior art, such as half bridges, bridges, dual systems and the like, are limited in their input voltage range by the limited maximum voltage of the semiconductors used as fast circuit breakers.

State-of-the-art pulse width modulators, such as B. the integrated module UC 1846 from Uπitrode, the advantages of which are described in detail in the "Application Handbook 1987-1988 page 148 - page 156 and are emphasized by the following quote:" The inherent advantages of eur rentmode control over conventional PWM appoaches to switching power converters read like a wish / ist from a frustrated power supply engineerP 'ei do not meet the tough requirements of the task. Even after

According to the manufacturer, the module tends to become instable with a controlled inverter at duty cycles above 50%, as explained on page 153, column 2, paragraph 2.

Elsewhere, there is a direct indication that this module is completely unsuitable for half-bridge converters because of the instability. Driver stages for high-performance converters, as described in detail in patent application P 40 22 176.8 "Modulator for controlling high-voltage transistors", are not suitable for this use without significant changes, because control was only designed for the operation of an inverter. In addition, the delay times in the circuit arrangement are too high for the critical application. In the case of high-voltage switching transistors of the bipolar type (current-controlled components), there is confusion in the specification of the maximum permissible operating voltage. The decisive criterion for the use of such components is not the limit value of the switch-off voltage, but rather the DC voltage that is applied indefinitely. Unfortunately, these values are very far apart. A value of approx. 8ooV collector - permanent emitter voltage must be assumed. In high-voltage switches of the type with voltage control (Power * MOS ^■ FET), which are available for maximum operating voltages up to 1500V, there is the increasing switch-on resistance (RDS-ON) and the physically related hypersensitivity to voltage peaks, even if they are only very short in time. serious obstacles to the use of these components.

IGBTs with operating voltages above 1000V are ruled out because of their too long switch-off and storage times for these conversion frequencies. Tyristors and GTOs are ruled out because of the relatively high conversion frequency, because their storage and switch-off times already take up more than 20% of the pulse duration of the pulse width modulation. Power transformers in a classic design are completely unsuitable for such an application because of the high demands placed on the dielectric strength, the resulting deterioration in the degree of coupling, and the increase in the leakage inductance. Disk transformers, as in patent application P 40 22 243.8 "Disk transformer" and their references, do not meet the conditions of high voltage insulation strength and reproducible physical properties, such as the constant and reproducible coupling factor in series production. In addition, the special operating state, that a transformer is fed from different with several primary windings from different electronic circuit breakers and transforms these medium-frequency AC voltages together, is not taken into account.

Driver transformers, as dealt with in application P 40 22 176.8 "Modulator for driving power transistors", do not meet the high requirements for the dielectric strength. This makes the entire modulator unusable for this application.

The use of chokes in a classic design as long inductors also fails due to the requirements for high dielectric strength. Requirements for dynamic operating behavior with regard to DC bias, extremely high current and voltage rise speeds make their use completely impossible

The state of the art listed with regard to processes of stress conversion when using assemblies and components according to the prior art shows that a solution is not possible when compared with the requirement profile for assemblies and components of the inventive device for high-voltage forming

The task in creating the device according to the invention is: reshaping a high voltage by cascading, in which an unregulated, strongly fluctuating high voltage, sometimes with frequent, short interruptions, is to be converted into a regulated output voltage with potential isolation. There is also the following profile of requirements for the device:

Medium frequency conversion frequency (in the range of 20 kHz)

Use of commercially available, cost-effective power semiconductor components

■ Design of an optimized power transformer from the point of view

Minimal dimensions, high dielectric strength, constant and reproducible power transmission properties, constant coupling factor, low leakage inductance

Adaptation of the core shape to the architecture of the windings

Composition of the core from commercially available embodiments

Reduction of masses and volumes compared to known solutions.

High insulation dielectric strength (lOkV, 50Hz) Lower manufacturing costs compared to known solutions.

^■ High reliability in long-term operation

Redundant security system for self-protection of the system and the environment. Extended temperature range. Reliability in mobile use ^■ Resistance to voltage peaks above the maximum operating voltage EMI values must not influence communication electronics The assemblies and components affected by the device according to the invention are: 1. POWER SWITCH; 2. PULSE WIDTH MODULATOR; 3. DRIVER LEVELS. 4. HIGH VOLTAGE SWITCHING TRANSISTORS; 5. POWER TRANSFORMER; 6. DRIVER TRANSFORMER; 7th thrush

On the other hand, the instruments available for solving this task must also be considered. Fundamental research to increase the collector - DC emitter voltage of fast power semiconductors are immediately excluded.

This problem cannot be solved with a physically constructive measure alone. The device according to the invention for high-voltage conversion by means of cascading is based on a modification of components and assemblies, the circuitry expansion and connection of components and assemblies, which each would not be suitable for a high-voltage application. The modification of the individual components with regard to the architecture brings about fundamental changes in the physical property in such a way that these components, which have been modified in this way, can only be used for high-voltage applications. A circuit-related expansion of the modules only results in their use in voltage ranges for which they are not designed. The inventive idea of the device, the linking, modification and expansion of assemblies and components, also includes an effective, redundant security system that ensures both operational reliability in the series application and the protection of the system and its environment in the event of a fault in the system. The consequent implementation of this method also compensates for the manufacturing-related specimen scatter of the specific parameters of the components. The absence or omission of only one component jeopardizes the reliability of this device.

This problem gave rise to the inventive idea of a device based on the following three pillars:

1. Ensuring a predetermined voltage division of the high voltage into partial voltages that can be processed by commercially available semiconductors, taking into account the - static operating states,

- dynamic operating conditions,

- Dynamic transition states.

2. Constructional modification of components to ensure

- physically technical requirements, - influencing the active properties of components.

3. Change of active properties of components through electrical wiring measures.

The correctness of the inventive idea of this device for reshaping high voltage has been demonstrated by the implementation using a case study that was tested under extreme conditions and has the following technical parameters:

Input voltage: 1.6kV - 3.9kV.

Output voltage: 55V constant. Output current: 0 ^■ 100A.

Output power: max. 5.5kW continuous rated power.

Working frequency: 20kHz.

Regulation by: pulse width modulation. Operating behavior: constant voltage / constant current.

Switching on: Start by contacting the high voltage power source.

Insulation resistance: Primary Jsec: 10kV, 50Hz sine, 10min

Power semiconductors: BUV 48C (high-voltage switching transistor). Circuit breaker.

Mass power unit: 15 kg. Mass power transformer: approx.3kg

Total mass: 32kg, consisting of:

Power part, input filter, additional protective devices and steel housing. Dimensions: 400 x 300 x 400 mm (L x Wx H).

Operation of the device:

The high voltage is fed via an input filter to a low-loss voltage divider, in which each divider of the cascade consists of a parallel connection of one active and one passive component. The partial voltages that arise in the cascade are each converted into pulse-width-modulated, medium-frequency AC voltages by an associated electronic circuit breaker. The thus formed DC voltages of the cascade are supplied to partial transformer systems in which the energy transfer predominantly takes place directly between the windings and which are mounted on a common core. The associated secondary windings of the partial transformer systems are connected in parallel to a rectifier and an output filter. All converters are controlled synchronously in time and polarity by a central trigger generator.

Additional monitoring and control electronics and safety electronics guarantee the safe operation of the system at all times in a safe map.

Description of components and assemblies: According to the invention, the input voltage, a high voltage into a predetermined number of partial voltages in a low-loss voltage divider, which keeps the division ratio of the high voltage constant in all operating states, both statically and dynamically, at idle speed, full load and in transition states , divided up. The transition states are particularly critical and difficult to control. Another critical operating state is the undefined application of the full operating voltage, as occurs, for example, in the contacting of an overhead line by the pantograph of a locomotive. System-internal capacities and series * supply * inductances in a generator with a very low internal resistance such as. B. in a remote rectifier station, lead to significant voltage spikes, such as these occur in series resonance circuits when a jump function is created.

Technically, the idea was solved by a low-loss voltage divider with an active and a passive component. The passive component consists of a capacitor with a high-ohmic resistance in parallel. In the cascade, this represents a frequency-compensated divider. The active component consists of a network of complex and control-dependent power resistors connected in parallel to the passive component. The complex part consists of the transformed load-dependent output resistance of the device with its complex parts of the output filter and the energy transmission path. The control-dependent load resistors consist of the power switches with their resistors in the switched-on state and the variable resistors during the switching on and off process. The advantage over all solutions is that the maximum alternating voltage that occurs on the assigned primary winding of the transformer subsystem corresponds to the amount of only the corresponding divider voltage. The individual AC voltages are superimposed on the DC voltage amount due to the position in the divider. (DC voltage as "offset"). The charge shifts that occur in the power transformer and the other components for potential separation, which are a function of the voltage rise rate, amplitude and frequency of the AC voltage, are only a fraction of those that occur when the high voltage is chopped with a cascade of power semiconductors one level.

The requirements for the insulation materials are significantly reduced. The resulting EMI values are considerably smaller compared to all other processes. The deformation of the individual partial voltages on the voltage divider in alternating voltages, as is required for a transformation, takes place in connection with a current or voltage regulation via a central, pulse-width-modulated driver signal for the individual circuit breakers within the cascade. The circuit breakers in this exemplary embodiment are self-oscillating inverters whose duty cycle in both current directions is determined by a common, external start * stop trigger signal time-synchronized. (Puis width modulation).

The pulse width modulated output voltage, whereby the same pulse width modulation is required for the positive and negative amplitude, is supplied to a separate transformer system, the requirements of which will be dealt with in detail in a later chapter. Stray inductance, degree of coupling and power transmission behavior of each individual partial transformer system must be identical. The partial transformer systems of the power transformer are mounted on a common core. The dimensioning of the capacitive component of the voltage divider must ensure that the amount of charge withdrawn from the dividing capacitor during the on-time of the inverter is very much smaller than the amount of charge of each individual capacitor of the divider. With such a link, the requirements regarding the static and dynamic operating states are fully met.

The critical part of the transition states is essentially determined by the switching behavior of the individual power semiconductors of each individual circuit breaker. The requirement for a time-synchronous course The output voltage of all power switches is solved according to the invention in that the power control signal for the power switches consists of two power signals which follow one another in time. The first power signal is defined in time duration and amplitude, the subsequent one, which is smaller in amplitude, is determined by pulse width modulation in the time duration. Both signals are generated in separate output stages of the trigger generator.

In very special operating conditions, such as. B. short circuit or "soft start" conditions in which the duration of the pulse width modulated signal is shorter than the duration of the first signal, the first signal is determined in its duration by the pulse width modulated signal. The very low internal resistance of the 1st signal with a high amplitude and time-defined, constant width prevents the course of the inrush current of the power semiconductors, which follows the R L constant, due to the inductances of the driver transformers and the generator series resistance of the output stage, and also causes a strong overload of these semiconductors. The effect of this circuit arrangement manifests itself in the time-synchronous and considerably shorter duty cycle of the individual circuit breakers. Influences of the scattering of the active components (high-voltage transistors) and passive components (such as the different inductances of the driver transformers) are thereby eliminated.

By connecting the primary windings of all driver transformers in parallel and connecting them to a central, fast circuit breaker as a short circuit in the output stage of the pulse width modulator, the time-synchronized, fast opening of the circuit breakers in the individual circuit breakers also takes place. The complex effect of the high voltage rise speeds on the cascade by suddenly applying the operating voltage was solved according to the invention as a result of tests and analyzes by interventions in three different levels of the device.

1. Limitation of the voltage rise rate to a predetermined maximum value by an upstream series filter. The effects are not combated with difficulty, but critical conditions are actively prevented. 2. Short circuit of the primary windings of all driver transformers via a mechanical contact of a relay in the rest position.

The remaining residual risk due to the uncoordinated switching on of individual power semiconductors in the power switches, caused by the critical voltage or current steepness of individual semiconductors being exceeded as a result of the charge shifts in the collector base capacitance, is increased by the feedback via the current jerk-transformer of the individual power switches by short-circuiting the primary windings of all driver transformers through a mechanical relay contact of a relay in the rest position. The relay contact is only opened when enabled by internal protective circuits, which are described in detail in a further chapter. 3. Blocking of the pulse width modulator if the characteristic map is exceeded or undershot by only one voltage monitor of each individual divider in the cascade.

All circuit breakers must be blocked when the high voltage is applied. The circuit breakers may only be controlled and activated by the pulse width modulator after the high voltage has been applied. Each inverter is assigned an undervoltage and overvoltage monitor with a defined working field between these two corner points, each of which independently outputs a potential-free enable signal to the logic electronics of the pulse width modulator.

For reasons of operational safety and protection against the consequences of the destruction of components with fire or explosion-like conditions due to the high energy content of the charge in the capacitive divider of the cascade, which could be triggered by the fault in a single circuit breaker in the cascade, the enable signal is blocked immediately . The automatic blocking of the enable signal is triggered by leaving the specified characteristic map by only one circuit breaker in the divider cascade, as is the case, for example, when a circuit breaker fails. According to the invention, the device not only includes the creation of safe operating states, but also active operational safety through redundancy of effective, fast electronic fuses in the event of malfunctions that can never be completely excluded. Mechanical fuses in accordance with the standards can only protect one circuit breaker, but do not prevent the remaining cascade from being switched on in the event of a fault. In addition, these fuses have large mechanical dimensions and response times that are too long in order to prevent, for example, an explosive bursting of power transistors.

The activation of the circuit breaker by the pulse width modulator in the event of a circuit breaker failure would result in the partial voltages reaching impermissible values due to the imbalance in the active components of the cascade, which would result in the subsequent destruction of further components.

Further embodiments of the invention emerge from the subordinate claims. The invention is explained in more detail in exemplary embodiments using the drawings. In these represent

Fig. 1. Block diagram with component symbol additions according to the invention of a system for the technical implementation of the device. Fig. 2a. Oscillograms of voltage profiles at the input and in the divider cascade. - Without filter. Fig. 2b. Oscillograms of voltage profiles at the input and in the divider cascade. - With filter.

Fig. 3. A in Fig. 1 block 1 shown divider of the cascade, consisting of capacitance, resistance, circuit breaker with associated voltage monitor (block 1 in connection with block 7), the associated current measurement (block 1 in connection with block 8) and the associated partial transformer system (block 1 in connection with block 2), as a circuit diagram. Fig. 4. Circuit diagram: rectification, screening, output voltage monitor with diagnostic system and "restart" automatic. (Fig. 1, block 4). Fig. 5. Current flow plan: pulse shaper, power driver stage. (Fig. 1, block 5).

Fig. 6. Current plan: pulse width modulator, current regulator 1, current regulator 2, voltage regulator, system monitoring. (Fig. 1; Block 6, Block 9, Block 10, Block 11, Block 12). Fig. 7a. Oscillograms: voltage curve before the filter when the high voltage is switched on as a function of time. Starting current of the system as a function of time. Fig. 7b. Oscillograms: Voltage curve in front of the filter when the high voltage is interrupted by the feeder Pantograph with arcing. Current flow of the system during the arc. Fig. 8. Oscillogram: Current curve through primary windings of the power transformer system after Stromtrans formation and rectification as a function of time. Fig. 9. Mechanical component for power transformer and filter choke; Cassette carrier plate for spirally cut windings made of copper foils.

Fig. 10. Sectional view of Fig. 9, Fig. 11. Sectional view of Fig. 9.

Fig. 12. Mechanical component for power transformer and filter choke; Cassette support plate for wire-shaped, single-layer copper windings. Fig. 13. Power transformer (block 2) side view. Fig. 14. Power transformer (block 2) top view.

Fig. 15. Secondary bobbin; Sectional view with 2 secondary windings, front view, rear view. Fig. 16. Primary bobbin; Sectional view with a primary winding, a technical embodiment of the inventive device for high voltage conversion with the necessary links and modifications is explained using a block diagram. For this purpose, the circuit arrangements contained in the blocks are explained using circuit diagrams, and the modified components used in the circuit arrangements are explained using technical drawings.

Block 1. TEILERKASKAE with circuit arrangement CIRCUIT BREAKER.

The high voltage divider consists of a cascade of parallel connection of active and passive components. The passive component consists of a parallel connection of capacitance and ohmic resistance. The active component consists of a circuit breaker with a partial transformer system of the power transformer at the output. The transformed variable output resistor with the complex portion of the power transmission chain appears as a parallel resistor in the form of an active component to the passive component via transformer and circuit breaker. The design of a divider of the cascade in block 1 is shown in FIG. 3. The design of the capacitor in the divider cascade differs depending on the type of circuit breaker used, whether half or full bridge. In the case example, a circuit breaker in a half-bridge configuration was used. In this type of inverter, the capacitor consists of the series connection of two capacitors, the capacitors being able to consist of a parallel connection of several capacitors. In terms of amount, all capacities in the cascade must be the same, except for the manufacturing tolerances. 3, the capacitance consists of the capacitors C111 to C113. The constant resistance component in the form of boho resistors, which are required for safety reasons to discharge the capacitors when switched off, is taken over by the resistors Rl 11 and Rl 12. The current flowing through the resistors is also used to supply and transmit the signal "Voltage monitor" used with group 710a, which is described in more detail in the corresponding chapter.

The maximum voltage at the "voltage monitor" circuit arrangement is limited by the Zener diode D 117.

CIRCUIT BREAKER. In the case example, it is a half-bridge with positive feedback, the duration of each switching period is determined by external "start" - "stop" signals.

Each circuit breaker in the divider cascade is controlled potential-free via its own driver transformer. In Fig. 3 it is the transformer Tr. 111. Incoming control pulses from block 5 (FIG. 1) switch on the transistors of the upper bridge branch, consisting of 0 113, Q 114 or of the lower bridge branch Q 111, Q 112, depending on the polarity.

The corresponding networks of diodes and capacitors between the corresponding secondary winding of the driver transformer Tr. 111 and the base of the associated transistors serve, on the one hand, to generate a negative bias voltage in the “off state”, and on the other hand, the diodes D 116, D 115 form an “anti-saturation circuit” for the power transistors. Correspondingly, the mode of operation of the diodes in the other bridge branch. The combination of R 113, C 118 and C 117 is a relief network when the respective power transistors are switched off. In addition, the high-frequency oscillation which arises in the switching-off process is damped by these elements due to the remaining leakage inductance of the partial transformer and parasitic capacitances. The load current at the output of the circuit breaker is transformed in phase with the primary winding of the driver transformer Tr.111 via a current feedback transformer Tr.112. This guarantees a load-dependent, optimal current control of the power transistors without an additional auxiliary voltage supply. The output current of the inverter is recorded via a current transformer Tr.113 and rectified in block 8 (FIG. 1, FIG. 3) and converted at burden R 811 into a pulsating DC voltage proportional to the load current, which in turn is fed via a busbar for the "Pulse by pulse" current control of the inverter is used.

DRIVER TRANSFORMER.

The high requirements of the device for high-voltage forming are:

^■ High ^{dielectric strength} .

- Greater complex resistance, to avoid a differentiation constant that interferes with the power control signal.

^■ Extremely short delay time between input * and output signal.

- Small sample variations of the complex resistance in series production.

- Small build volume.

- Small coupling capacity between the primary and secondary winding. - Low manufacturing costs.

The conditions of the requirement profile are partially diametrical and are not solved according to the state of the art. According to the invention, the tasks were solved below.

Deviating from the classic design, the primary winding and secondary windings are applied to separate, cylindrical, chamber-shaped winding cores, which are pushed together when wound

A core of the EE * or EC design is used as the core The two secondary windings Fig. 15, .2 and .3 are in foil form on two adjacent chambers Fig. 15, 4 and 5 of a winding former Fig. 15 .1 housed

The winding ends π "A", "E" are led out on the two lateral end faces through the slotted webs to one side

The secondary windings are located on the thinner winding koper, through the inner hole of which the middle bar of an EC core runs.

The outer diameter of the winding body with the secondary windings corresponds to the inner diameter of the cylindrical winding body FIGS. 16, .6 for the primary winding .8 The primary winding is cylindrical

Wire winding designed and housed in the winding chamber .7.

By press fitting the coil form with each other, the windings are encapsulated, resulting in a high dielectric strength

By spatial separation and positioning of the winding body that the winding ends on different sides of the

Emerge, the dielectric strength increases again.

A plastic cylinder is pushed onto the bobbin wound with the primary winding

The wound bodies consist of temperature-resistant materials with a low dielectric constant, such as. B polyamide

The construction according to the invention ensures a defined minimum distance between the windings over the entire winding area with a small construction volume. The windings are thus encapsulated in plastic

The assembled arrangement of nested, wound bobbins with an outer iso-sleeve and core is cast in a plastic trough. Due to the winding geometry designed for series production and the distant spatial arrangement of the Pπmar coil to the core at the same distances from the secondary coil, the specimen scatter of the transformers is again low and negligible with regard to the pulse transmission behavior. The impulse running times in

Transformer systems are load independent and negligible

POWER PRINCIPAL TRANSFORMER.

The profile of requirements for the power feedback transformer corresponds to that of the driver transformer. Apart from minor deviations, the design is identical. Instead of a two-part secondary winding, there is only one one-part winding

Both winding cores each have only one winding chamber. The secondary winding is also applied to the thinner winding chamber (smaller spatial distance from the core).

VOLTAGE MONITOR. Fig. 3 The current through the resistors of the divider cascade is proportional to the input voltage. In the circuit arrangement of the voltage monitor, the current is converted into a voltage. In the event of undervoltage, the transistor Q 713 keeps the light-emitting diode D 713 short-circuited. The diode D 713 and the photo transistor 0 714 are used for potential-free signal transmission and are both arranged in a dark plastic tube. The distance between the two components corresponds to the safety requirements for the insulation dielectric strength.

When the lower threshold voltage of the working field, which is determined by diode D 712, is exceeded, current flows through transistor Q 712, which leads to transistor Q 713 being blocked. The diode D 713 has current flowing through it and emits a light signal. When the upper threshold voltage of the working field, which is determined by the Zener diode D 711 and the resistors R 715, R 716, is exceeded, a current flow through 0 71 1 begins. The D 713 is short-circuited, the control of Q 714 is interrupted.

The significant advantage of this circuit arrangement is that no additional auxiliary supply with high requirements for insulation dielectric strength is required. The already existing divider current is used for measurement, power supply of the circuit arrangement and signal transmission. The voltage at the phototransistors resulting from the operating state is amplified and fed to a comparator.

The logic state of all the comparators is linked. Only in the event that all the light-emitting diodes of the individual monitoring electronics are in operation is there an enable signal for the modulator and an opening of the mechanical relay contact which short-circuits all primary windings of the driver transformers.

Block 2.

POWER TRANSFORMER.

The device according to the invention is based on the uniformly proportional distribution of the energy transfer of the individual dividers of the cascade.

In the dynamic operating state, the uniform voltage distribution in the divider is to be ensured by the precise splitting of the secondary-side total load by transforming partial loads with the same amount parallel to the individual stages of the voltage divider. This task is performed by the power transformer (FIG. 1, block 2), which is divided into a number of sub-transformer systems which correspond to the number of sub-voltages in the voltage divider. The magnetic flux generated by the partial transformer systems flows through a common core. Each partial transformer system consists of at least one current-carrying primary winding in cheese construction, which is fed from its own power source (circuit breaker) and at least one current-carrying secondary winding in cassette construction, which are separated on both sides of the primary winding by insulating material. An absolutely identical power transmission behavior is the main requirement of the device. In transformers for medium-frequency power transmission, the degree of coupling between the windings, the leakage inductance and the phase shift of the magnetic fields of the energy transmission between the windings and the energy transmission through the core are dominant physical parameters. The reproducibility of these parameters with only small specimen variations is an unconditional requirement of the device for the power transformer component. Due to the device, there is also the high requirement for dielectric strength between primary and secondary.

The fulfillment of the requirements in this concentration is not fulfilled by any state-of-the-art transformer, not even by the disc transformer.

According to the invention, these requirements, such as reproducibility of the degree of coupling and the leakage inductance with high insulation resistance in series production, are solved by the architecture of the power transformer and in the configuration of the windings as “finished components”. The construction and design of the individual primary and secondary windings as "prefabricated components" places high demands on the construction with regard to the mechanical properties, such as. B. vibration resistance, temperature resistance, resistance to high humidity with simultaneous use of high voltage. From these requirements, the idea according to the invention arose to design a plastic plate on both sides in such a relief that a spiral winding is sunk into the plate on each side. After embedding the windings, the relief-like plastic plate is closed on both sides by thin, glued insulating plates. The carrier plate is broken through in the area of the spiral start of the windings at a point such that contacting the winding starts is possible. It is only important to ensure that the winding direction of each spiral is directed in the opposite direction. The interior of the plate is broken through in such a way that a core made of soft magnetic material can be inserted through the plate. The plates have centering and fastening holes at the corners. At the end for the electrical connections of the spiral windings, openings are created through which potting compound or liquid can penetrate in order to soak the winding in a vacuum.

The result is a cassette with defined and reproducible insulation in every area of the winding, in accordance with the requirements for insulation strength for high voltage. The technical implementation of such cassette carriers is shown in FIG. 9 as a top view of one side and the sectional representations of FIGS. 10 and 11. Basically, it is possible to shape such a shape from a solid insulating material plate by milling. Another possibility is the production as an injection molded part made of polyamide or a similar plastic. A third type of implementation consists in the form-fitting connection of prefabricated individual parts. In the case example, the production from individual parts was chosen. On a carrier plate made of 0.5 mm thick epoxy resin, FIG. 9 .1, in which an inner window .5 is cut out, plastic frames .2; .3; .4 glued to the edges of the plate. The material thickness of the frame material should be about 0.1mm thicker than the thickness of the spiral winding. A plastic frame .6 with the same wall thickness is glued on both sides of the inner window .5 of the panel. The ridge web width was chosen to be 4mm. The geometry of the winding spiral forces the carrier plate to be asymmetrical. The outer frames are broken through on the longer part of the plate. The spiral winding is electrically contacted at these points. Above the inner frame in the direction of the opening, the support plate is pierced by a small window (Fig. 9, .7). The geometric dimensions of the inner window are due to the core geometry given.

The centering and fastening bores (FIGS. 9, .8) must be at exactly the same distances from the associated symmetry axes.

When rotating the cassette by 180 ° in the drawing plane, the holes and the inner window must be absolutely congruent.

In the sectional representations of FIG. 9, FIGS. 10 and 11, the reference numbers of FIG. 9 were used in each case in order to better illustrate the symmetry of the relief in relation to the mounting plate .1.

The type of cassette carrier in FIG. 9 is matched to the special requirements of a winding in the form of a spiral-shaped cut copper plate. The opening .7 through the carrier plate .1 has the width of a spiral fertilizer winding. The ends of the spiral windings on each side overlap in the area of the window .7 and are electrically connected to one another. Pay attention to the opposite spiral course. The outwardly leading ends of each spiral on each side of the carrier plate are preferably designed in such a way that a simple, external connection between the individual prefabricated components is possible. It is advantageous to fix the ends on the carrier plate with small tubular rivets. After embedding the windings, the carrier plate is closed on both sides with a plastic plate made of insulating material, for example a 0.5 mm thick glass fiber reinforced plastic plate with the same geometry as the carrier plate. The plates are made by applying an adhesive to the webs of the inner names .6 and .2; .3; .7 the outer frames are positively connected. The cassette manufactured in this form is a "prefabricated component". When designing the winding in the form of a spiral made of copper wire, a more optimal design is recommended, as shown in Fig. 12.

A plastic frame .6 is glued to both sides of the carrier plate with a central window. The web is asymmetrical on one side and ramp-shaped up to half. The height of the ramp depends on the wire thickness used. The ramp is directed in such a way that the winding begins behind the ramp and runs in a clockwise direction. The carrier plate is drilled through in the area of the falling flank of ramp .7 in order to insert the wire for the winding on the other side.

The prefabricated plastic plate is wound on both sides in a special winding device. After a provisional fixation of the winding, the outer frames .2; .3; .4 glued on. After this step, the manufacturing process is the same as for the type of cassette already described. The material thickness of the inner and outer frames is determined by the wire thickness and a safety margin of approx. 0.2 mm. The web width of the inner and outer frames corresponds to the requirements for voltage insulation resistance.

The overall transformer system shown in block 2 of FIG. 1 of the exemplary embodiment is shown graphically in FIG. 13 as a side view. The power transformer consists of 6 sub-transformers, Tr. 210 to Tr. 260. Four threaded bolts .7 are screwed into a foot made of insulating material .5. The "prefabricated components" are placed on the stud bolts in the following order: insulating plate .1; 0.2mm Micanit cassette .2; (Copper plate spirals) connections on the left insulating plate .1; 0.2mm micanite Cassette .3; (Copper wire spiral) connections on the right insulating plate .1; 0.2mm Micanit cassette .2; (Copper plate π spirals) connections on the left insulating plate .1; 0.2mm micanite. Spacer sleeves .4 (4 rings made of 4mm thick glass fiber reinforced plastic with 12mm outer and 5.5mm inner diameter. The assembled parts result in the partial transformer system Tr. 210.

The subtransformer systems Tr. 220 to Tr. 260 mounted.

Spacer bolts (Fig. 13 .4) are inserted between the partial transformer systems. The resulting intermediate spaces enable the power transformer to be cooled better and the compact thermal masses to be reduced. The package of finished parts is completed with two solid strips of GRP and pressed together by 4 M5 nuts. The presentation of washers and sawtooth rings was dispensed with because they are irrelevant for comprehensibility.

The core is composed of a 6-part ferrite material, material N 27. In the case of two cores, the center webs are cut out from "E" shaped starting pieces of the E55 series, so that two "U" shaped pieces are created. With 2 "E" shaped starting pieces, the two outer legs are separated, the four "I" shaped webs are created.

For reasons of better assembly, better stability and to avoid corona formation on the sharp edges of the ferrite pieces, the "I" -shaped core pieces are pushed into two "U" -shaped GRP profile slides, FIGS. 13 and 14 .9, which with the surface facing the windings. The rails are about 5mm longer on each side than the stack of finished parts. The two "U" shaped core pieces .8; .12 on the top and bottom of the winding stack with the two 'T' shaped webs .13, which are embedded in profile rails .9 made of GRP, form a ring of ferrite material around the winding stack, which runs through the central window. The sections of ferrite material are mechanically compressed by a brass tensioning strap .10 in Fig. 13 and 14, which surrounds the ferrite ring on the outside and held under tension by means of a screw .1 1 on the top of the transformer. If necessary, such a construction can be mounted on the other side of the center window in the winding stack. With a continuous rated power of 5.5 kW, the core described above is fully sufficient.

The architecture determines the core design compared to the classic systems in which the windings are adapted to the cores according to DIN standards. The great flexibility due to the modular composition of the cores offers the advantage of an inexpensive core design.

The described construction of the cassettes and the assembly of the "finished parts" to form a power transformer offers the advantage of the optimal design of the windings and precisely reproducible positioning of the windings with respect to one another.

The prerequisites for low copy dispersion in series production are thus given. The use of a Micanit plate was described between the individual cassettes. Insulating materials often do not simultaneously meet the electrical and mechanical properties required by the process. For this reason, two materials with the respective optimal properties were used in pairs. Micanit offers the advantage of maintaining its mechanical strength even at extreme temperatures. The transformer subsystems and the power transformer can be soaked in a vacuum. The material for impregnation can be made through the openings in the outer frame for contacting the winding ends. The number of turns of each transformer subsystem is dimensioned such that with a minimum input voltage at the high-voltage divider, taking into account the dead time of the energy transfer in the associated power switch and the voltage drops on the power semiconductors in the primary and secondary circuit, the given Output voltage is reached. The maximum output current corresponds to the total current divided by the number of dividers in the cascade. The associated outputs of the secondary windings of the partial transformer systems are conductively connected to one another in the form of a “parallel connection”.

A final summary of the sub-area power transformer shows that the demand for equal energy distribution in dynamic operating conditions within the high-voltage * divider is proven by the following physical processes in the power transformer and its transmission behavior. Synchronization of the magnetic field within the power transformer through a common core.

• Leg flow of the neighboring sub-transformer systems via electromagnetic coupling within neighboring sub-systems, and the resulting balancing of the transmission power. - The onset of differential current flow in the secondary windings in the event of asymmetries in the output voltage forms of the AC voltages at individual circuit breakers within the cascade. The resulting pulse shape of the current flow in the primary winding is recorded by the monitoring electronics and the necessary control measures are carried out.

Block 3.

INPUT FILTER. 1, block 3, has three essential protective functions for the downstream circuit breaker cascade.

1. The defined limitation of the rate of voltage rise when high voltage is applied.

2. The cutting of rapid voltage peaks that are superimposed on the high voltage.

3. Avoidance of the transmission of the interference voltages generated during the process in the system into the supply network.

The filter consists of a series inductance and a subsequent capacitance against minus, which in principle represents a series resonance circuit. The consumer, the divider cascade, which represents a load-dependent damping of this resonant circuit, is connected in parallel to the capacitance. For reasons of dielectric strength, the capacitance can also be designed as a series connection of capacitors. The series inductance is split into 6 partial inductors, which are designed in a cassette design like the power transformer and are mounted on a common core with an air gap. The windings are electrically connected in series. The greater part of the windings connected in series are, depending on the requirements for blocking voltage strength diodes connected in series and in reverse with parallel capacitances for voltage distribution. A diode with parallel capacitance and a series resistor is connected in parallel to the remaining windings.

The capacitance switched against minus is carried out for reasons of the dielectric strength in series connection of capacitances with parallel ohmic resistors in order to ensure a discharge of the capacitances in the switched-off state for safety reasons. The physical property of a series resonant circuit, when a step function is applied, with a damped oscillation determined by values from inductance and capacitance, is modified by the external parallel connection with diodes in such a way that only the delayed voltage rise of the rising flank of the sine wave with a small one Voltage overshoot in the positive direction, which is caused by the damped portion of the total inductance, remains. The part of the inductance damped in the reverse direction by a series resistor with a diode, however, offers the advantage of a complex series resistor for AC voltage components which are superimposed on the DC voltage. In addition, there is still the effect of an interference filter of the system with respect to the high-voltage source. A cascade of varistors is connected in parallel with the capacitors, the varistor voltage amount of which exceeds approximately 10% of the nominal voltage at the maximum input voltage.

In the case example: nominal voltage 3kV, maximum voltage 3.9kV; 10% reserve 300V. Varistor voltage 4.2kV. (5 VDR - resistors in series with surge current of 2000A / 20μsec; an energy absorption of 5x 190W / 2msec and a varistor voltage of 5x 820V. Metrologically, the comparison of a voltage curve under nominal voltage conditions at the input of the divider cascade could not be carried out without a filter because the The resulting peak voltages without a filter would immediately destroy the circuit breakers, as can be clearly seen in the oscillogram, Figure 2a, in which large overshoots of 1.6 kV occur with an input voltage of only I kV. In Figure 2a (1) the voltage curve is at Input of the divider cascade, which consists of only 2 dividers, is represented by an oscillogram.To obtain the same voltage conditions on the divider cascade as they occur during normal operation, only a divider cascade consisting of 2 dividers and a corresponding input voltage from IkV could be used. What is striking is the strong negative part of the tension retention fes after applying the positive supply voltage. The following 60% overshoot shows the dangers for the semiconductors in the divider cascade. The oscillogram Fig. 2a (4) shows the voltage curve on the 1st divider of the cascade of 3.6 kV. The time and amplitude-synchronous course of the voltages is clearly visible. The effectiveness of the filter design as a sub-component of the device according to the invention has been clearly proven.

Block 4.

RECTIFIER and FILTER. The symbolic representation of this assembly in FIG. 1 block 4 is shown in detail in FIG. 4 using a circuit diagram. In the device according to the invention, the circuit arrangement performs the following tasks: rectification of the pulse-width-modulated AC voltage. - Screening and smoothing of the pulse width modulated, rectified AC voltage.

- Change of the complex resistance vector at the exit of the system.

^■ Fast protection device when a pre-selected upper voltage limit is exceeded.

- Inverters blocked when overvoltage protection is activated with status analysis and restart. - Decoupling the output and the protective device from the load, for example of accumulators. The pulse width modulated AC voltage on the busbar of the partial transformer systems is fed to a two-way rectifier. This consists of the arrangement of fast diodes D 410 ■ D 417 with low forward voltage. The capacitor resistor network on the rectifier diodes, consisting of R 411 to R 414 and C 410 to C 413, serves to dampen high-frequency resonance oscillations that arise from the variable diode capacitances and remaining stray inductances of the power transformer. In addition, the voltage distribution is forced when diodes are connected in series.

The downstream inductor L 410 changes the complex resistance vector at the output in such a way that the complex resistance transformed into the output of the respective circuit breaker by the partial transformer does not represent a short circuit for the circuit breaker cascade. A capacitive resistance of -j O.l lmOhm is connected in parallel with the load resistor at a nominal load of 0.55 Ohm. This would be without a complex

Series resistance, which is formed by L 410, represent an impermissible short circuit for the circuit breaker in the switching process of the circuit breaker. The application-specific dimensioning of the inductance and the capacities fulfills the requirements for the residual ripple. In the case example at 100A and 55V with a longitudinal inductance of 45 // H and a total capacitance of 6x 600 // F, this is about 500mV. Additional safety systems are integrated in the process for reasons of operational safety and reduction of the risk potential for people and material. So e.g. the output of the system is secured with a length diode D 419 and a fuse Si 410 in the event that components fail on the secondary side of the inverter, or other fuses respond. In the case example, large lead accumulators are connected as a load. The consequences of a short circuit in the system output without the fuse system can be easily estimated.

There is also a considerable danger that, in the event of a high voltage skipping in the primary circuit onto the secondary circuit, for whatever reason, it is diverted to ground by a fast switch. Reasons could be unforeseeable, significant overvoltages, material defects in the insulation material or a mechanical crash. In this case, a power thyristor is ignited when an output voltage of BOV is exceeded, which short-circuits the output of the filter. In the event of a high-voltage breakdown, the fuse is destroyed by this short circuit in the input of the high-voltage filter. The protective function is fully fulfilled. Without the diode D 419, the fuse Si 410 would immediately melt in the output due to the battery voltage and the system would fail completely. Devices using this method are used in rooms with considerable electromagnetic interference fields, such as electric locomotives. A false triggering of the Th 410 thyristor by electromagnetic radiation in the "Gate * Zone" can never be excluded despite interference suppression measures. An automatic diagnosis and safety electronics monitors the output of the filter in the device according to the invention. Two different operating states must be distinguished from the electronics:

1. Start of the system with voltage ramp-up.

2. Malfunction with drop in output voltage.

The thyristor Th 410 is responsible for a hard short circuit of the system output. For this reason, no components may be arranged in this circuit that could endanger the effectiveness of this protective circuit in the event of a high voltage breakdown. The conducting state of the thyristor cannot be detected and diagnosed via a current flow through the thyristor, but only indirectly via the voltage state at the thyristor. The following evaluation and fuse electronics create the necessary control commands for the circuit breaker cascade. As already mentioned, the high-voltage conversion system has a constant-voltage constant-current

Characteristic. In constant current operation, the output voltage is a function of the load resistance and sometimes takes on very low values. There is only a very small voltage window for automatic diagnosis

Available.

The heart of the diagnostic system is a 1-stage comparator IC 414, whose 10 outputs are set to "Logical 1" in "DOT" mode and jump to "Logical 0" in 0.5V increments between 0.5V and 5V depending on the input voltage. The divider consisting of R 436, D 437, R 438 and R 433 allows a linear status diagnosis of the output voltage between 0 and 8V. The parallel connection of D 442 to R 437 and R 438 creates a magnifying glass for this area. The logic linkage and evaluation of the states at the comparator outputs takes place in the "NOR gate" of the IC 412.

In the state of "Logical 0" of all 4 inputs, the transistor Q 410 is actuated via a further "Or" link, consisting of the diodes D 424, D 425 and D 426. By activating the relay Re 410, the "voltage monitor" input is activated "short-circuited on the pulse width modulator. This switching state has priority over the enable signal by the voltage monitors of the divider cascade and forces the blocking of all circuit breakers in the cascade.

The rising edge at the output of IC 412 triggers a pulse with a defined duration at the Mαnofiop IC 410, which maintains the blocking state for the circuit breakers via an "OR connection", the diode D 425. The lock is required to discharge the capacitors in the output filter so that the Th 410 can safely extinguish. An overvoltage on the cathode of diode D 418 automatically triggers a blockage of the circuit breakers. The Zener diode D 422 becomes conductive and drives transistor Q 411. IC 411 inverts the logic state and controls the transistor Q 410 via D 424, the function of which has already been described.

The undisturbed starting of the circuit breaker of the cascade during the "soft start" is ensured in the following way: In the range between 0 and 0.5 V, the "H" state of an input of the IC 412 through R 424 deactivates the electronic fuse. If the 0.5 V upper limit is exceeded, the D 440 0 416 is switched through. Q 416 controls via R 433 and D 432 IC 413, which in turn one through R 430 and C 425 in its Time constant triggers a specific pulse and the "H" level keeps the fuse switched off, although the simultaneous activation of Q 412 via D 428 and R 426 causes the input with the only "H" level to drop to "0". If the voltage rises further between 1.5 and 4.5 V, Q 414 takes over from Q 416. If the output voltage exceeds the 5 V level during the time constant of IC 413, the comparator of IC 414 remains the only one at "0". Q 413 is controlled via D 430 and holds the electronic fuse blocked via an "H" level at an input of IC 412

If the output voltage falls below 5 V in the event of a malfunction (short circuit caused by the connected loads or Th 410 triggered), Q 413 is blocked and Q 414 is conductive, and the electronic fuse trips. The lock is maintained until the voltage at the cathode of D 419 is less than 0.5V. The behavior of the electronic fuse offers the advantage that in the event of a malfunction, by triggering Th 410 with an EMI pulse greater than 80 V at the cathode or greater than 0.7 V at the gate, the thyristor is automatically extinguished by switching off the device and discharging the filter capacitors C 415 to 422 becomes. The system automatically tries a "RESTART" again. If there is no malfunction due to a short-circuit in the consumer circuit or the high-voltage fuse responding, the system works again without any problems. Such an electronic fuse significantly increases the operational reliability of the method according to the invention and considerably reduces the maintenance expenditure on the system for high-voltage conversion.

The arrangement of R 410 for continuous current measurement and current control is selected so that the circuit currents of the filter are not recorded.

Block 5.

TRIGGER GENERATOR:

The device according to the invention places very high demands on the trigger generator for the circuit breakers, which are not met by prior art drivers.

Integrated driver circuits according to the prior art cannot be expanded in such a way by additional external wiring that they could meet the following requirements.

- Very small internal resistance in the event of a short circuit in the current feedback transformers in the circuit breaker of the Teiterkaskade with the "Stop" command for the circuit breaker with current coupling.

Decoupling the pulse voltage at the primary winding of the driver transformers compared to the circuit breakers of the auxiliary voltage source, the amplitude of which is greater than the auxiliary voltage as a function of the load current when the power switch is also coupled.

■ Defined pulse duration of a switch-on overload with very low internal resistance when the "Start" command is given. In Fig. 1 block 5 the core of the power driver stage is symbolic, in Fig. 5 in detail as a circuit diagram.

The device for high-voltage conversion requires the following controls of the driver transformers for operating the circuit breakers in the cascade and the associated switching states of the circuit breakers of the trigger generator bridge: Circuit breakers of the cascade "OFF": Switching state of the bridge of the trigger generator: Q 510 and Q 511 "On". Q 520, Q 518, Q 521, Q 519 "Off". Circuit breaker of the cascade "ON": Upper switch of the half-bridge configurations. Switching state of the bridge of the trigger generator: Switching on: Q 520, Q 518, Q 511 "On". Q 510, Q 519, Q 521 "Off".

PU width modulation: Q 520, Q 511 "On". Q 518, Q 519, Q 521, Q 510 "off". Circuit breaker of the cascade "OFF": input described.

Circuit breaker of the cascade "ON": Lower switch of the half-bridge configurations. Switching state of the bridge of the trigger generator: Switching on: Q 519, Q 521, Q 510 "On"; Q 518, Q 520; Q 511 "Off".

Puis width modulation: Q 521, Q 510 "On"; Q 519, Q 518, Q 520, 511 "Off". Only by expanding the bridge by a further, separately controlled circuit breaker in the upper bridge branch with an "or" link in the "supply energy" state, all the requirements of the device are met. The bridge is powered by an auxiliary voltage of 19 ^• 24V. The pulse width modulated control signal for push-pull control at the output of a pulse width modulator is unsuitable for these requirements. In an additional pulse shaper stage, the logic combination and generation of the switching signals for the 6 switches (Q 510, Q 511, Q 518, Q 519, Q 520 and Q 521) takes place in accordance with the requirements of the device.

With logic "L" at the outputs of the pulse width modulator, Q 510 and Q 511 must be conductive to short-circuit or keep short-circuited the primary windings of the driver transformers. Logical "H" at an output of the pulse width modulator opens the bridge circuit breaker assigned to it (Q 510 or Q 511). The rising edge at one of the outputs of the pulse width modulator triggers a pulse with a defined duration via the "0R" gate IC 516. The "AND" gate IC 517 is linked to the signal of the pulse width modulator. The pulse width at the output of the trigger generator is never longer than the smallest pulse width of the pulse width modulator, although a pulse was generated for the switch-on override with a defined period of time. This circuit-technical measure is of crucial importance for the dynamic transition behavior of the circuit breakers in the cascade of dividers.

To shorten the switching times for switches Q 518 and Q 519, the respective gate is operated via a switched constant current source with switch-on override when switching on and a short circuit when switching off. The exemplary embodiment is described with reference to Q 518 and also applies analogously to Q 519. Q 527, D 532, D 533 and R 522 form a constant current source which is activated by "H" at the output of IC 517c. During the switch-on process, the current is determined by the voltage curve at C 511, which results in an optimal switching behavior of Q 518. The short circuit at the gate of Q 518, caused by Q 522 and α 526, is canceled simultaneously by the complementary control signal to Q 527.

The same operating procedures apply analogously in the other diagonal of the trigger generator. Block β; 9; 10; 1 1; 12th

Pulse width modulator; Voltage regulator; Current controller primary current; Current controller

Ausqanqsstrom.

Because of the complex interactions between blocks 6, 9, 10, 11 and 12 in FIG. 1, the description of these blocks has been summarized. The detailed representation as a circuit diagram is shown in FIG. 6.

State-of-the-art pulse width modulators do not meet the tough requirements of the device for high-voltage conversion in several respects. In the case of integrated circuits, use in the system according to the invention can only be achieved by outsourcing certain functions, changing the specific characteristics and linking them to additional, external circuits. The large dynamic range of the input voltage and the output current in connection with two different control characteristics places very high demands on the stability of the control. The pulse width modulator has the task of converting one or more analog values with a predetermined priority into pulse widths in a defined time frame. The recurring compromise between integrating the analog values as a stability factor for the control and short control times in the event of step functions occurring in the system causes considerable difficulties. In addition, even small changes in the pulse width cause large deviations in the initial values of the system. The high demands on the control cannot be solved by a control loop. The solution to the problem of stable operation of the energy conversion system in the device for high-voltage conversion according to the invention consists in: Decentralized detection of disturbance variables at critical points on the energy conversion path.

- Splitting a control function on two control loops with different control time constants.

- Design of the priority criteria for the disturbance variables.

- Networking of the individual disturbance variables within the energy conversion path.

- Increase in sensitivity in the comparison points. The device according to the invention for high-voltage conversion can no longer be based on a control loop, but it already represents a relatively simple cybernetic system.

The dominant control characteristic of the system is the constant voltage. If the preselected maximum current value is exceeded, the system must continuously change to the control characteristic of the constant current. Even in the "constant voltage" operating mode, a portion of the rapid current control of the primary current is subordinated to the voltage control in order to prevent larger differences in the current amplitude between two successive pulses.

In all operating states that can occur in the process, there is no direct functional dependency between output current and primary current through the windings of the transformer system block 2, FIG. 1. Monitoring and limiting the primary current is a prerequisite for safe system operation. The function of the current control is split into two subfunctions primary current control and output current control with separate "actual value" * acquisition. The control variables are processed in separate control systems with different control time constants and are fed into the overall system at different points. A prerequisite for the stability of the control is a very small deviation of two successive pulse widths for controlling the circuit breakers in the half-bridges within the divider cascade. The method "PULS BY PULS CURRENT * REGULATION" for inverters, which the manufacturer "UNITRODE" propagates from integrated circuits for pu width modulation, is considered unsuitable even for half-bridges.

Although not a half-bridge but a cascade of half-bridges is used in this application, this type of control can be used successfully due to the design of the periphery of this module according to the invention. When implementing the pulse width modulator, the state of the art is used, as is customary in the market in an integrated module UC 1846 from Unitrode.

The subsequent functional description relates to the circuit diagram shown in FIG. 6. The oscillator function of the block must be removed from the block for reasons of stability and for further derivations from this signal. The clock frequency is determined by the external circuitry of IC 611, the pause time by the external circuitry of IC 612. IC 610 is operated with an external frequency via emitter follower Q 610.

The external wiring of the voltage regulator "EfA" in the IC 610 according to the manufacturer, an additional sawtooth function is connected to the "actual value" of the output voltage via R 1212. In the normal comparison between the amount of the reference voltage and the amount of the output voltage, a large temporal tolerance field arises because the intersection of two almost parallel lines is determined. Although the "actual value" is falsified by switching a sawtooth AC voltage, the absolute value of the output voltage in the steady state is considerably more precise than without this measure. In addition, the tendency to jitter caused by the undefined intersection of two almost parallel lines has been eliminated.

The sawtooth function arises at C 613 as an integral of the voltage state at the complementary output of IC 612, which is controlled by the oscillator frequency. The subsequent emitter follower Q 611 decouples the sawtooth generator from the impedances of the subsequent networks and prevents repercussions.

The basic idea of the IC manufacturer to generate the pulse width modulation not by comparing the output value with a fixed comparative value, but by comparing it with the ramp-shaped function of the primary current through a transformer, is good from the approach and, in practice, already comes up when operating an IN ¬ verter already on considerable difficulties. 1. The angle of inclination of the ramp depends on several factors.

2. The switch-on override triggers a malfunction because of the higher amplitude than the final amount of the ramp. By combining three measures according to the invention, the basic idea of the IC manufacturer can be used for the application of high-voltage conversion with high demands. The measures are:

1. Integration of the rectified alternating voltages.

Fig. 1 block 8a to 8n. The voltages are proportional to the current flow through the pri- märwicklungen the power transformer, Fig. 1, block 2. Integrator: R 1019, C 1013.

2. Linking the integrated amount of current with a ramp-shaped AC voltage, which is derived from the oscillator frequency. Linking of transformer current via R 1019 with sawtooth function at Q 611 via R 1052 and R 1021 at the non-inverting input C / S; X3 from IC 610.

3. Discharge of the integration capacity during the pause, to create constant initial conditions for successive pulses.

Discharge of C 1013 by Q 1010. This very fast current regulation allows current limitation during the start phase and rapid changes in the input voltage. The sieve and filter capacities have to be loaded during such settling conditions. These complex loads cause high current peaks that are independent of the load. An output current control independent of the input voltage is only possible through a current sensor in the output circuit outside the filter circuit currents. The voltage drop across a shunt resistor of 1 mOhm in the minus path of the output current (FIG. 4, R 410) is preamplified by the IC 1010 and supplied to the current regulator IC 1011. This branch has no influence until the point of use of the current control. When the setpoint that can be set by R 1015 is exceeded, a discharge of C 615 by Q 612 proportional to the duration of the exceeding takes place. The output values of IC 1011 are integrated. The short-circuit currents in the output are reduced to that by a different choice of the integration time constant Discharge of filter capacities limited The time constant for the downward integration is determined by the discharge * current through 0. 612, the upward integration through time constant of R 617 and C 615. The DC voltage level at C 615 looped in at pin 1 of IC 610 is a limitation for the Voltage swing of the control amplifier EfA in IC 610. The lower the voltage at the amplifier EfA, the smaller the pulse width and thus the output voltage. The current control of the output current takes place indirectly via the regulation of the output voltage.

This auxiliary circuit considerably reduces the fast control dynamics of the output voltage control during the start phase, which results in a "soft * start".

Critical operating states, such as rapid successive shutdowns and reclosing of the input voltage, are considerably alleviated by the transition from rapid voltage regulation to slow voltage control with a preselectable time constant. These critical operating conditions arise when there is poor contact between the overhead line and the pantograph of the locomotive on icy overhead lines and can occur for long periods. The inherent dynamics of the voltage profiles in the high-voltage circuit as a result of arcing and effects on the high-voltage conversion system can only be mastered by the device according to the invention, and use of the system under such extreme conditions is only possible. The fuse and monitoring circuits of blocks 710a in conjunction with 710b to 7π0a in conjunction with 7n0b in FIG. 1 as a block diagram and FIG. 3 as a circuit diagram also intervene in the control system at pin 1 of IC 610 via processing electronics. Q 911 is only blocked in the "H" state of all voltage monitors in the cascade and when an auxiliary voltage for the electronics of at least 19V is present at the inputs of a "NAND Schmitt * Trigger" IC 911. At the same time, transistor Q 910 is driven via IC 910. Q 910 actuates relay 910, which in turn short-circuits all primary windings of driver transformers Tr. 111 to Tr. n11 (FIG. 3) in the divider cascade block 1 FIG. 1. The blocking of Q 911 causes a charging of C 910. The voltage state at C 910 is monitored via an emitter sequence Q 912 and a "NAND-Schmitt trigger" connected downstream. As long as the voltage at C 910 has not exceeded the switching threshold of IC 912, the pulse width modulator IC 610 is blocked by state "H" at the output of IC 912. The system is supposed to keep this additional time constant locked during the transient processes when the pantograph contacts the overhead line. It is a further measure to increase operational safety. The effectiveness of the method described so far has been proven on the basis of measurements of dynamic operating states.

The voltage curve at the input of the filter was examined in an electric locomotive under actual operating conditions. The expression of the following measurement is shown in FIG. 7a. With a 4-channel storage oscilloscope, the voltage curve at the filter input was measured when the main switch was actuated, using a high-voltage divider 100: 1 with a downstream probe 10: 1. Curve curve 1. The current profile of the current measuring transformers of the divider cascade was shown on channel 4. The automatic triggering for a "single shot" took place when a voltage level of 3.75 kV was exceeded. The DC voltage on the overhead line was 3.08 kV. The system load current was 75A. Immediately after the main switch is actuated, an oscillation with an amplitude of approx. 3 kV and a frequency of approx. 320 Hz can be seen. A maximum value of 4.875 kV is measured. The switch-on delay of 20msec and a gentle current increase can be clearly seen in the illustration of the current profile of channel 4. Since the measurement is digital, the time scale is 20msec | Div, but the frequency of the current is 40kHz, the amplitude curve is incorrect. Only the envelope curve of the current curve can be used for measurement purposes. 7b, the dynamic voltage processes during the process of interrupting the voltage supply by lowering the pantograph from the overhead line were measured and recorded. The behavior of the system during an arc in the input circuit is thus examined. The use of the arc is made visible by the position of the "start marker". The trigger was also set for a "single shot" when a voltage level of 3.75 kV was exceeded. A swinging of the input voltage between 3.75 kV and 1.6 kV for a period of 60 msec is recorded here. The response function of the system can be clearly seen from the envelope of the primary current. During a voltage drop to an amount of 1.6 kV after approx. 35 msec, the current drops almost to zero, rises again to its previous value when the high voltage rises. It should be noted that the dominant load resistance is lead accumulators, which have a non-linear current-voltage dependency.

If the input voltage drops after 6omsec. below 1.5 kV, the clear blocking of the system can be recognized immediately by responding to the voltage monitor. Although the input voltage due to the charge of the gates in the input filter only slowly sinks, the transformer current is zero.

The measurements clearly prove that the technical exemplary embodiment of the device for high-voltage conversion according to the invention can process even extremely critical operating states without problems. The accuracy of the theoretical explanations and circuit description is based on a further measurement in

Fig 8 proved. The rectified primary current through the power transformer is shown on channel 4 after the potential separation by the current transformers. The frequency is 40kHz, the peak amplitude at the end of the period is 15.6A. Due to a connected load, the pulse excitation for the main brake of the locomotive, the system has switched to constant * current * mode (97.5A). The current curve clearly shows the device-related "shading override", the exact "PULS by PULS" current * control and the frequency stability.

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Claims

claims

1 . Device for high voltage conversion by cascading in which the high voltage in the form of

The same or rectified alternating voltage in a low-loss power voltage divider (Fig.1.1.) Is forced to be synchronized in all operating states into equal partial voltage amounts, each power voltage divider optionally consisting of an arrangement of circuit breakers in a bridge configuration with parallel connection of one or more capacitors and an ohmic one Resistor or in half-bridge configuration (Fig. 3) with parallel connection of two capacitors in series connection with parallel ohmic resistances, in the diagonal of the respective circuit breaker arrangement is the primary winding of a partial transformer system and the device has the following features:

Design of the power transformer (Fig. 1.2 .; Fig. 13; Fig. 14.) with dominant energy transfer directly between the windings in cassette design for the isolated encapsulation of the

Winding, which in turn is made up of a number of self-contained, uniform partial transformer systems with at least one primary winding to be supplied and adjacent current-carrying secondary winding, which corresponds to the division ratio, and all partial transformer systems are mounted on a common core with a small amount of energy transfer, and the partial transformer systems have the complex power - resistance

Component of the divider stage, the transformed part of the load resistance with the complex parts of the output filter of the device.

Control of the associated electronic circuit breakers within the divider cascade, in

Bridge or half-bridge configuration, for generating a pulse-width-modulated, medium-frequency AC voltage via driver transformers, each assigned to the associated divider cascade, with the same transmission behavior, with a time-synchronized, time-defined override of the switch-on process of each half-cycle from a common trigger generator with five possible operating states {Fig. 1.5; Fig. 5) and linkage with the current transformers with the same transmission behavior, from the divider cascade potential-free transformed respective load currents with simultaneous operation of the power switches in the "quasi-saturation range", the electronic power switches representing the control-dependent power resistances of the divider cascade , whose time-synchronized instantaneous values of the resistors within the cascade are forced by external wiring. Shutdown of all associated electronic circuit breakers within the divider cascade due to simultaneous interruption of the driver current from the trigger generator, forced, time-synchronous short-circuiting of all transformed load currents on the primary windings of the driver transformers connected in parallel in every half period by the trigger generator with simultaneous relief of the circuit breakers by a parallel connected relief network .

Protection of the circuit breakers within the divider cascade against impermissible voltage and current rise rates by connecting the cascade in series with a filter (Fig.1.3.), The series inductance of which is designed in a cassette design

Protection of external consumers from the consequences of a high voltage flashover thanks to fast overvoltage protection with evaluation electronics and "restart" (Fig. 4.) of the system

False triggering.

Symmetry of the current profile through all primary windings of the power transformer

With the help of recording all partial currents through the primary windings of the power transformer via current measuring transformers with the same transmission behavior, linking the instantaneous values of the primary currents, evaluation and processing in a downstream "pulse by

Pulse "current control (Fig.3 .; Fig. 6) and conversion into a pulse width modulated signal for the downstream trigger generator.

Monitoring the minimum-maximum voltage range on each divider of the cascade with one

Monitoring electronics (Fig.1.7 .; Fig.3.) With potential-free transmitted locking signal for the entire device when exceeding the map of only one divider within the cascade (Fig.6.).

2nd Device for high-voltage conversion according to claim 1, characterized in that the two windings of the respective cassettes of the power transformer are designed as disk-shaped windings made of copper wire, insulated wire or spirally cut copper plates, which have opposite directions of winding in a carrier plate (Fig. 10; Fig. 11 12) made of insulating material with inner and outer webs of insulating material embedded and mechanically fixed in their position, the minimum distance of the windings from the inner and outer webs of the core made of soft magnetic material by plastic webs, the distance between primary and secondary windings by plates made of insulating materials.

3rd Device for high-voltage forming according to 1 or 2, characterized in that the individual windings of the power transformer through the cassette construction with each other in all three axes of the spatial coordinate system fixed, ensure a constant coupling factor of the partial transformers.

4th Device for high-voltage forming according to claim 1, characterized in that the core shape made of soft magnetic material is adapted to the winding architecture.

5. Device for high-voltage conversion according to claim 1, characterized in that the electronic circuit breakers in the divider cascade are designed as voltage-controlled or current-controlled components.

6. Device for high-voltage conversion according to claim 1, characterized in that the common trigger generator (Fig.1.5 .; Fig. 5.) can assume five possible operating states: (output short-circuited; + current source with low internal resistance and defined duty cycle, + current source with preselectable resistance and variable Time duration; - current source with low internal resistance and defined duty cycle; - current source with selectable internal resistance and variable duty cycle), the maximum duty cycle always being determined by the variable duty cycle as a function of pure width modulation.

7. Device for high-voltage conversion according to claim 1, characterized in that, in the mode of pulse width modulation, the duration of the switch-on pulse is never longer than the duration of the pulse width modulation

8th . Device for high-voltage conversion according to claim 1, characterized in that the primary windings of the driver transformers (Fig. 1.9.) Of the individual circuit breakers in the cascade are short-circuited by a mechanical relay contact, which is opened by the release for pulse control and as protection of the device when the high voltage is applied with the control electronics switched off

9. Device for high-voltage conversion according to claim 1, characterized in that the driver transformer and the current feedback transformer (Fig. 15; Fig. 16) in each divider of the cascade is designed in such a way that the primary winding and the secondary windings each on one own cylindrical winding cores made of insulating material are applied, the cylinders are pushed together due to their different diameters in the wound state on a common core made of ferromagnetic material, preferably in "E" or "EC" design and as a complete The entire assembly is poured into the insulating material or immersed in a container with insulating oil.

10th Device for high-voltage conversion according to claim 1, characterized in that it is preferably an "L-C" filter which is prevented by the special design of the winding and external circuitry of the series inductance, the typical resonance oscillation of a series resonance circuit when a jump function is applied. This is done by parallel connection of diodes in the reverse direction and small capacitances in parallel to the diodes for most of the winding. The remaining rest of the winding is connected in parallel with a combination of resistance and parallel connection of diode in the reverse direction with capacitance connected in parallel to the diode

11. Device for high-voltage conversion according to claim 1 or 10, characterized in that the series inductance is split into partial inductors, which in turn are designed in a cassette design and have a common core made of soft magnetic material.

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