HK1192378A - Power supply assembly with an inverter for creating single phase alternating current - Google Patents

Description

Power supply device with inverter for generating single-phase alternating current

Technical Field

The invention relates to a power supply device comprising an inverter for generating a single-phase alternating current and comprising a transformer which comprises a primary winding and a first secondary winding and a second secondary winding, wherein the secondary windings have the same number of turns and are arranged such that the secondary windings are flowed through by the same magnetic flux during operation of the transformer, such that the same voltage can be tapped off at the secondary windings during operation of the transformer, wherein one terminal of the first secondary winding and one terminal of the second secondary winding are connected to one another at a first node, a two-phase system being produced between the first node, the other terminal of the first secondary winding and the other terminal of the second secondary winding, the phases of the two-phase system being offset from one another by 180 °.

Background

Such a power supply device is known from document EP2346150a1 (see fig. 1b therein). It is known from the same literature to use a first power supply device for supplying a silicon rod for producing polycrystalline silicon according to the siemens process. The power supply devices shown in fig. 1b of EP2346150a1 each have two outputs at which voltages offset by 180 degrees from one another, i.e. in phase opposition, are provided. The voltage drives a medium-frequency current having a frequency between 1 and 100kHz into the silicon rod. The voltage in opposite phase is generated by two transformers, each having a primary winding and two secondary windings.

The secondary coils are connected to each other at a first node. Each first node is connected to a neutral terminal of an output of the power supply device. The other terminal of the secondary winding is connected to an outer conductor terminal in the output.

In addition to the supply of power by the first power supply device, the silicon rod may be supplied with power by a second power supply device at the same time as the first power supply device, as described in EP2346150a 1. Silicon rods are connected in series to the second power supply device. The power supply is performed with a current having a frequency of about 50 Hz.

Document EP2346150a1 discloses that the first supply device and the second supply device are decoupled from one another by a capacitor. For this purpose, a capacitor is inserted between the outer conductor terminal of the output and the further terminal of the secondary winding of the transformer. The capacitor together with the other components forms a high-pass filter which prevents the current driven by the second power supply from flowing into the first power supply and damaging or destroying the first power supply. In contrast, the second power supply device is thereby decoupled from the first power supply device, since the voltage at one output of a first power supply device is cancelled by the inverted voltage at the other output of the same first power supply device.

When the loads on the outputs of the first power supply device are not equally large, then problems may of course arise in practice. In particular, if the inductance of one load is greater than the inductance of the other load, a somewhat significant difference in the value of the voltage provided at the respective output of the first power supply device may occur. This results in the sum of the voltages at the outputs of the first supply device no longer being 0. Instead, values of more than 100V are reached. The voltage reached can be dependent on the frequency at which the first power supply is operated.

The uneven application of the first power supply device and the resulting voltage at the respective output of the series connection of the first power supply device can result in the second power supply device being damaged or destroyed.

Disclosure of Invention

The object of the present invention is therefore to further design the first supply device in such a way that differences between the voltage values at the outputs of the first supply device described at the outset are avoided as far as possible.

This object is achieved by the invention in that a capacitor is arranged in series with the primary winding of the transformer or between the first node and the neutral connection of the output of the power supply device.

The capacitor connecting the first node to the neutral connection or the capacitor connected in series with the primary winding is in the circuit with the first secondary winding of the power supply device and the second secondary winding both directly or indirectly, i.e. with the intermediate transformer, during operation of the power supply device. The capacitor can thus be used to compensate for differences in the value of the voltage at the outputs of the power supply device. The capacitor can have a capacitance of 2 to 10 μ F, in particular a capacitance of 4.5 μ F, in particular if it is arranged on the secondary side.

When it is assumed that the transformer is replaced by an equivalent circuit, the equivalence of the arrangement of the capacitor in series with the primary coil of the transformer on the one hand and between the first node and the neutral terminal on the other hand becomes clear. It is thus clear to the person skilled in the art that a capacitor arranged on the primary side also acts in both load circuits.

Preferably, the other terminal of the first secondary coil is connected to the first outer conductor terminal, and the other terminal of the second secondary coil is connected to the second outer conductor terminal. The invention makes it possible to significantly reduce the voltage between the outer conductor terminals compared to the state of the art.

For example, it is conceivable for the respective outer conductor terminal to be connected directly to the further terminal of the secondary winding. It is thus possible that the voltage between the outer conductor terminals is 0V or close to 0V even when the outputs of the power supply device are not loaded to the same extent, in particular when the resistive-inductive loads have different load-inductance fractions.

However, it is also conceivable for the outer conductor terminal to be connected to the further terminal of the secondary winding via a capacitor. In this case, the voltage between the external conductors can also be reduced when the output of the power supply device is subjected to different loads. But the reduction is not as significant at this time as if the capacitor at the outer conductor terminal were eliminated.

This object is also achieved according to the invention in that the voltage can be adjusted discontinuously or continuously by means of at least one of the secondary windings. Discontinuous adjustability of the voltage can be achieved by having a plurality of taps on at least one of the secondary windings. If the voltage is adjustable by means of at least one of the secondary windings, the voltage can be varied such that the voltages on the loads connected to the power supply device according to the invention are equal in value.

Another solution according to the invention consists in arranging capacitors between the further terminals of the secondary windings and the outer conductor terminals of the output, at least one of the capacitors having an adjustable capacitance. With such an adjustable capacitor it is also possible to achieve that the voltages across the loads connected to the supply device according to the invention are equal in value.

The inverter may be an H-bridge with power transistors.

The power supply may have a frequency converter and the inverter may be part of the frequency converter. In addition to the inverter, the frequency converter may have a rectifier and a direct current intermediate circuit.

Alternatively, the frequency converter may also be a direct frequency converter (direktemrichter). The inverter is an integrated component of the direct-conversion converter within the meaning of the invention.

The power supply device according to the invention may be part of a reactor for producing polycrystalline silicon according to the siemens process. The power supply device according to the invention may be a first power supply device which supplies an alternating current for induction heating to the silicon rod or silicon thin rod. The silicon rods or thin silicon rods may be arranged in a reactor vessel. A holding part is provided in the reactor vessel, by means of which the silicon rod or silicon thin rod is held. The holding part is at the same time an electrical terminal, by means of which the silicon rod or the silicon foil rod is connected into the load circuit.

The reactor may have a second power supply for supplying the silicon rods or silicon thin rods with an alternating current for induction heating. The second power supply device may have a transformer with a plurality of secondary-side taps and a power regulator connected thereto, which is operated in the voltage sequence controller and is connected to the outer conductor terminals of the second power supply device, as is also disclosed, for example, in EP2346150a 1. The frequency of the alternating current that can be generated by the first power supply means is 1 to 1000kHz, and the frequency of the alternating current that can be generated by the second power supply means is 10 to 100 Hz.

Drawings

Further features of the invention will become apparent from the ensuing description of preferred embodiments with reference to the accompanying drawings. The attached drawings are as follows:

fig. 1 is a circuit diagram of a power supply apparatus according to the prior art;

fig. 2 is a circuit diagram of a first power supply apparatus according to the present invention;

fig. 3 is a circuit diagram of a second power supply apparatus according to the present invention.

Detailed Description

The power supply device according to the prior art shown in fig. 1 has a frequency converter comprising a rectifier 1, a direct current intermediate circuit 2 and an inverter 3.

The rectifier 1 is connected to the outer conductor L1 'and the neutral conductor N' of the power supply facility. A capacitor is connected to the output of the rectifier, said capacitor forming a direct current intermediate circuit 2. The inverter 2 is connected to the dc intermediate circuit 2.

The inverter 3 is an H-bridge formed from IGBTs 31, as it is widely used in inverters. Instead of IGBTs, other controllable switches can also be used. The primary coil 41 of the transformer 4 is connected to the parallel circuit of the H-bridge. On the secondary side, the transformer 4 has two coils 421, 422. The two secondary coils are arranged on a core and are flowed through by the same magnetic flux. The secondary coils 421, 422 have the same number of turns but are wound in opposite directions.

One terminal of each of the one secondary winding and the other secondary winding is joined at a node K1. An electrical connection is established by this node to the neutral terminal N on the output side of the power supply device.

The other terminal of each secondary coil 421, 422 is connected to the outer conductor terminals L1, L2 on the output side of the power supply device through capacitors C1, C2.

The power supply device provides two voltages of opposite phase at its output terminals L1, N and L2, N, which have the same value in idle mode and in symmetrical loading of the output terminals L1, N, L2, N. The voltage between the outer conductor terminals L1, L2 is then 0V.

The asymmetrical loading of the outputs can result in the values at the two outputs L1, N, L2, N not being equal. The voltage between the outer conductor terminals L1, L2 is then not 0V. The deviation can be in the order of magnitude, which is problematic for the integration of the power supply device into larger devices, depending on the frequency of the alternating voltage at the output and depending on the manner of loading. In particular in different inductive loads, the alternating voltages can be separated from one another during operation of the power supply. Especially when operating the power supply to provide alternating current with a frequency close to the resonance frequency of the output circuit comprising the secondary coil 421, the capacitor C1, the load RL1, LL1 or the secondary coil 422, the capacitor C2, the load RL2, LL2, a high voltage may result between the outer conductor terminals L1, L2.

This voltage can be reduced significantly if, like the first supply device according to the invention according to fig. 2, which otherwise corresponds to the supply device according to fig. 1, a capacitor CN is inserted in the connection between the node K1 and the neutral terminal N.

By means of the capacitor CN, a coupling of the output circuit is produced, which results in a reduction of the voltage between the outer conductor terminals L1, L2. The voltages at the output terminals L1, N, L2, N are compensated compared to the case of the asymmetrical loading described with reference to fig. 1. The voltage may be reduced up to about 80%.

When the capacitors C1, C2 in the connection between the further terminals of the secondary windings 421, 422 of the transformer 4 and the outer conductor terminals L1, L2 are replaced by wire connections and only the capacitor CN between the first node K1 and the neutral terminal is present, a reduction of approximately 100% of the voltage between the outer conductors can be achieved in the case of an asymmetrical application, in particular an asymmetrical resistance-inductance application, of the output terminals L1, N, L2, N, as is shown in fig. 3 for the second circuit arrangement according to the invention, which otherwise corresponds to the first circuit arrangement according to the invention according to fig. 2.

Claims (7)

1. Power supply device comprising an inverter (3) for generating single-phase alternating current and comprising a transformer (4) comprising a primary coil (41) and a first secondary coil (421) and a second secondary coil (422), wherein the secondary coils (421, 422) have the same number of turns and are arranged such that they are flowed through by the same magnetic flux during operation of the transformer (4) such that the same voltage can be tapped off at the secondary coils (421, 422) during operation of the transformer (4), wherein one terminal of the first secondary coil (421) and one terminal of the second secondary coil (422) are connected to one another at a first node (K1), a two-phase system being generated between the first node (K1), the other terminal of the first secondary coil (421) and the other terminal of the second secondary coil (422), the phases of the two-phase system are offset from each other by 180 DEG, characterized in that,

the first node (K1) is connected to a neutral terminal (N) of the output of the power supply via a capacitor;

arranging a capacitor in series with a primary coil of a transformer;

the voltage can be discontinuously or continuously adjusted by at least one of the secondary coils;

and/or capacitors are arranged between the further terminals of the secondary windings and the outer conductor terminals of the output, at least one of the capacitors having an adjustable capacitance.

2. The power supply device according to claim 1, characterized in that the other terminal of the first secondary coil (421) is connected with a first outer conductor terminal (L1) and the other terminal of the second secondary coil (422) is connected with a second outer conductor terminal (L2).

3. The power supply device according to claim 2, characterized in that a capacitor (C1) is connected between the other terminal of the first secondary coil (421) and the first outer conductor terminal (L1), and a capacitor (C2) is connected between the other terminal of the second secondary coil (422) and the second secondary coil (L2).

4. A supply device according to any one of claims 1-3, characterized in that the inverter (3) is an H-bridge with power transistors (31).

5. The supply device according to any one of claims 1 to 4, characterized in that the supply device has a frequency converter (1, 2, 3) and the inverter (3) is part of the frequency converter (1, 2, 3).

6. Reactor for producing polycrystalline silicon according to the siemens process, comprising a first power supply device for supplying alternating current for induction heating to silicon rods or silicon thin rods which can be arranged in a reaction vessel, characterized in that the first power supply device is a power supply device according to any one of claims 1 to 5.

7. Reactor according to claim 6, characterized in that the reactor has a second power supply device for supplying the silicon rods or thin silicon rods with an alternating current for induction heating, wherein the frequency of the alternating current that can be generated by the first power supply device is 10 to 1000kHz and the frequency of the alternating current that can be generated by the second power supply device is 10 to 100 Hz.