Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M5/00—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases
  • H02M5/02—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC
  • H02M5/04—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters
  • H02M5/22—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M5/275—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M5/293—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only

Definitions

• the present invention relates to a method and a device for electronically regulating and controlling AC voltages.
• the AC voltages in question are those that are common in public power supply networks.
• the typical frequency in Europe is 50 Hz, in the U.S.A. and other countries, for example 60 Hz.
• frequencies around 400 Hz are used.
• the invention relates to an AC voltage control, which, depending on the design, can be used between a voltage frequency of zero and up to 10 kHz.
• the order of magnitude of the mains voltage in public networks is always at a nominal voltage value between zero and 500 V. ..
• the AC voltage for current consumers is mainly regulated by phase angle controls, by inverter circuits or by means of vibration packet controls.
• the voltage is regulated by cutting off a certain part of the phase, which causes a point of discontinuity in the voltage curve. This will induces many harmonics or harmonics that can be derived from the Fourier transformations.
• Electrical stor consumers regulated in this way to the Neüz therefore have undesirable network perturbations which have a negative effect on the quality of the power supply network.
• the AC voltage sine curve of the power supply network is superimposed by these, in some cases high-frequency harmonics or harmonics, and to a certain extent contaminated.
• phase control Another side effect of the phase control is the reactive current, which is withdrawn from the network depending on the phase angle between the current and the voltage. This electricity places an unnecessary strain on the energy distribution network and must therefore be kept within limits. Above certain limits, therefore, elaborate reactive current compensation systems with audio frequency locks used. These are essentially capacitors and decoupling inductors connected in parallel, by means of which the reactive power is brought to almost zero. In addition, reactive power meters are also installed so that the purchased reactive power can be offset.
• a second known type of AC voltage regulation takes place by means of a so-called Variacs with an optional servomotor.
• This is an electromechanical device. It allows only a low adjustment speed and has been displaced today for reasons of price and space. It is only used for laboratory purposes.
• inverter Another option for regulating AC voltages is the inverter.
• This is a device that first generates a DC voltage, i.e. processes the AC voltage using a rectifier-capacitor circuit, and then uses an inverter to generate a controllable single-phase or three-phase AC voltage with a controllable frequency.
• Such inverters primarily produce harmonics due to their rectifier-capacitor circuit, which in turn must then be eliminated from certain limits by means of specially designed suction circuits. Inverters are also relatively expensive in terms of material prices.
• electronic AC voltage switches should also be mentioned. There are some circuits that allow an AC voltage to be switched with the aid of a Grai rectifier and a transistor. However, such an AC voltage switch has so far only been used as a replacement for a relay switch.
• the object of the present invention is therefore to create a method and a device for regulating and controlling alternating voltages from the public distribution network, which solves the problems mentioned at the beginning.
• the method according to the invention and the device for exercising it should enable AC voltage regulation and control, which eliminates the drawing of reactive power from the network and avoids the occurrence of harmonics.
• This object is achieved by a method for regulating and controlling AC voltages from the public distribution network, in which the input voltage is regulated by means of pulse width modulation and subsequent filtering directly into an AC output voltage which lies within the envelope of the AC input voltage.
• the device for performing the method is characterized in that at least two AC switching elements are present between the terminals of the input voltage, between which the output voltage is tapped, these switching elements being able to be activated alternately for pulse width modulation.
• the device and the method operate with little loss. No harmonic harmonics are generated and no additional reactive power is drawn. For specific loads (for example fluorescent tube systems), a partial harmonic compensation of the load is even possible by a special choice of the output curve shape (by means of modulation).
• the voltage regulation according to the invention can be used quite generally for regulating AC voltage, in particular also as a voltage stabilizer and as Three-phase voltage regulator. It is suitable, for example, for light control, for controlling motors, and as a soft start control. For the user, their advantages lie in saving energy costs by, for example, a hardly noticeable reduction in the intensity of light in the case of fluorescent tubes. Furthermore, an extended service life of the starting devices and fluorescent tubes due to a reduction in the operating voltage can be expected. In addition, no suction circuits are required for the suppression of harmonics. Furthermore, no additional reactive current compensation systems are required, which means that smaller bundle current compensation systems can be used in comparison to devices with phase-angle control.
• the voltage regulation according to the invention if used to a greater extent, helps to save energy, to optimize the network utilization and to maintain a network that is free of flow with respect to harmonics.
• Figure 1 A schematic diagram of the inventive device
• Figure 2 The AC voltage switch from Figure 1 in its interior structure
• FIG. 3 another construction of an AC voltage switch with Grford rectifiers.
• FIG. 1 The basic structure of the device according to the invention is shown in FIG. Following the input filter 1, a bidirectional switchover element 2 is arranged between the terminals of the input voltage.
• the basis of the operation of the device is a direct pulse width modulation of the alternating voltage with specially connected fast alternating voltage switching elements in the inside of the switching element 2.
• a power switch is thus formed which is suitable for the regulation of any loads from zero to approx. 50 kW / kVA .
• the core of the device consists of the switching element 2, which can process both positive and negative input voltages U. That is, alternating voltages as well as direct voltages of any polarity.
• FIG. 2 shows the basic circuit of the changeover element 2 or the power changeover switch 2 on the basis of a detailed and enlarged view compared to FIG. It includes two AC voltage switching elements 4, 5, between which the terminals for the output voltage U are connected, these switching elements 4, 5 being alternately activatable for pulse width modulation.
• the AC voltage switching elements 4, 5 consist here of an anti-serial connection of two power semiconductors .., T 7 and T 3 , T. each with a diode D 1 , D 2 and D 3 , D 4 connected antiparallel to them. If one considers one half of the switching element 2, or the upper switching element 4, and the first power semiconductor T. is switched on, the current flows through this first power semiconductor T- when the input voltage U.
• the diodes D - D. can both components of the power semiconductor 1 ⁇ -T. (Power Mos Fet or IGET), but can also be external, i.e. discrete, as shown.
• the course of the modulated AC voltage U. is shown schematically in Figure 1.
• a certain proportional output voltage U t of the same curve shape can be generated, the value of the voltage naturally always running inside the envelope of the input voltage U. If modulation is only carried out over half a period and the pulse widths are varied, the output voltage U t can have any curve shape. This application is primarily of interest for the compensation of any harmonics that occur, that is, if a load exhibits a non-linear behavior.
• FIG 3 shows an alternative device which can also be used for the same purpose.
• the AC voltage switching elements 4, 5 therefore each include a Griger rectifier circuit D 5 and D g , the AC voltage inputs of which form the connections of the AC voltage switching elements 4, 5 and a power semiconductor between their DC voltage outputs -Element T 5 or T g is connected.
• the two AC voltage switching elements 4, 5, whether for a circuit according to FIG. 2 or according to FIG. 3, are particularly advantageously formed by industrially manufactured hybrid modules.
• the invention makes it possible to achieve a largely sinusoidal power-current curve by regulating the AC voltage accordingly by pulse width modulation.
• the method and the device can be operated in the range between zero and up to 10 kHz.
• the voltage can take any course within the envelope of the input voltage U- n , depending on the variation of the pulse widths and pulse pauses.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Inverter Devices (AREA)
• Ac-Ac Conversion (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=4260200

Family Applications (1)

Country Status (5)

Cited By (2)

Families Citing this family (2)

Citations (3)

• 1989
  • 1989-10-04 CH CH3634/89A patent/CH679704A5/de not_active IP Right Cessation
• 1990
  • 1990-10-01 WO PCT/CH1990/000232 patent/WO1991005401A1/de not_active Ceased
  • 1990-10-01 EP EP19900914048 patent/EP0452431A1/de not_active Withdrawn
  • 1990-10-01 AU AU64335/90A patent/AU6433590A/en not_active Abandoned
  • 1990-10-01 CA CA 2042589 patent/CA2042589A1/en not_active Abandoned

Patent Citations (3)

Non-Patent Citations (1)

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