Power supply unit and circuit breaker

Abstract

Provided herein is a power supply unit (1) for use in a three-phase alternating current system, comprising: a transformer (2); and a first phase conductor (L1), a second phase conductor (L2) and a third phase conductor (L3) forming respective first, second and third primary windings (31, 32, 33) of the transformer (2), the winding direction of the third primary winding (33) being opposite to the winding direction of the first and second primary windings (31, 32), and / or the number of windings of the third primary winding (33) is different from the number of windings of the first primary winding (31) or the second primary winding (32). Further, an electronic circuit breaker (10) is provided herein.

Description

Technical Field

[0001] This article provides a power supply unit and a circuit breaker. Background Art

[0002] Circuit breakers can be used to protect electronic circuits from short circuits and / or to protect electrical equipment (e.g., electric motors) from electrical overloads. Digital or electronic circuit breakers may include electronic components, such as a control unit or a trip unit, that are configured to monitor the current flowing through the circuit breaker during operation. These electronic components typically require a power supply unit. For example, the power supply unit can extract power from the current flowing through the circuit breaker during operation. In this case, no additional connections are required to supply power to the trip unit. For example, where the circuit breaker is used in a three-phase AC system, the power supply unit can extract power from one or more of the three phases. However, if one or two of the three phases fail or are lost, it may be desirable for the power supply to the trip unit to remain functional so that the circuit breaker remains functional even in the event of a phase failure or phase loss. Summary of the Invention

[0003] It is at least one object of certain embodiments to provide a compact power supply unit for use in a three-phase AC system that remains functional if all but one of the three phases fail.

[0004] This object is achieved by the subject matter of the independent claims. Further embodiments and further advantageous developments are provided in the dependent claims.

[0005] According to one embodiment, a power supply unit for a three-phase AC system includes a transformer. Specifically, the transformer transfers electrical energy from a primary circuit to a secondary circuit via electromagnetic induction. The primary circuit and the secondary circuit may be electrically isolated from each other. For example, the transformer includes a magnetic core, one or more primary windings connected to the primary circuit, and one or more secondary windings connected to the secondary circuit. Furthermore, the transformer may be configured to convert an AC input voltage into an AC output voltage having different amplitudes. For example, the input voltage is provided by the primary circuit, while the output voltage is applied and / or provided to the secondary circuit. For example, the amplitude of the output voltage may be greater or less than that of the input voltage.

[0006] The magnetic core is configured to guide or direct magnetic flux. For example, the magnetic core directs magnetic flux generated by current flowing through one or more primary windings to one or more secondary windings. For example, the magnetic core has a toroidal, rectangular, shell-shaped, or any other form or shape useful for a transformer. Preferably, the magnetic core comprises a magnetic material having a high magnetic permeability, such as iron or a ceramic ferrite material.

[0007] For example, one or more primary windings and / or one or more secondary windings comprise electrically insulated wire wound around a magnetic core. If the transformer comprises more than one primary winding, the primary windings may be electrically insulated from one another. If the transformer comprises more than one secondary winding, the secondary windings may be electrically insulated from one another. Each winding of the transformer may comprise a predetermined number of turns. Herein and hereinafter, the number of turns of a given winding specifies the number of times the wire of said winding is wound around the magnetic core. The number of turns may be an integer. Alternatively or additionally, the number of turns may also comprise a fractional part of an integer if a turn of a winding is only partially wound around the magnetic core. For example, a turn that is partially wound around the magnetic core is wound around a portion of the circumference of the magnetic core.

[0008] According to another embodiment, a power supply unit for a three-phase AC system includes a first phase conductor, a second phase conductor, and a third phase conductor, forming a first primary winding, a second primary winding, and a third primary winding, respectively, of a transformer. For example, the AC voltage and / or AC current between each pair of the first phase conductor, the second phase conductor, and the third phase conductor are 120° out of phase. In particular, each of the first phase conductor, the second phase conductor, and the third phase conductor comprises a wire that is wound around a magnetic core of the transformer and forms the first primary winding, the second primary winding, and the third primary winding. Preferably, the first primary winding, the second primary winding, and the third primary winding are electrically insulated from each other.

[0009] According to another embodiment of a power supply unit for a three-phase AC system, the third primary winding is wound in a direction opposite to the winding directions of the first and second primary windings. For example, the first and second primary windings include turns wound clockwise around the magnetic core, while the third primary winding includes turns wound counterclockwise around the magnetic core, or vice versa. In other words, the third primary winding has a different polarity than the first and second primary windings.

[0010] Because the third primary winding has a different winding direction than the first and second primary windings, the magnetic flux generated by the AC current flowing through the third primary winding has an additional phase shift of 180° compared to the magnetic flux generated by the AC current flowing through the first and second primary windings, respectively. In other words, the current induced in the secondary winding of the transformer by the AC current flowing through the third primary winding has an additional 180° phase shift compared to the current induced in the secondary winding by the AC current flowing through the first and second primary windings.

[0011] According to another embodiment of a power supply unit for a three-phase AC system, the third primary winding has a different number of windings than the first or second primary windings. Herein and hereinafter, the number of turns of a winding is equal to the number of turns of that winding. For example, the third primary winding may have a greater number of turns or a smaller number of turns than the first or second primary windings. For example, all three primary windings may have different numbers of windings, or the first and second primary windings may have the same number of windings.

[0012] According to a preferred embodiment, a power supply unit for a three-phase AC system comprises:

[0013] - transformers; and

[0014] - a first phase conductor, a second phase conductor and a third phase conductor, forming a respective first primary winding, a second primary winding and a third primary winding of a transformer, wherein

[0015] - the winding direction of the third primary winding is opposite to the winding direction of the first primary winding and the second primary winding, and / or

[0016] The number of windings of the third primary winding is different from the number of windings of the first primary winding or the second primary winding.

[0017] The power supply unit disclosed herein is based on the idea that for each of the three phases, only a single transformer is used, rather than three separate transformers. Consequently, the power supply unit described herein is particularly compact. Furthermore, since all three phases are coupled to the same transformer, the power supply unit will generate an electrical output voltage and / or an electrical output current even if one or two of the three phases fail or are lost. Consequently, the power supply unit described herein is particularly robust against the loss of all but one of the three phases. In contrast, if only one of the three phases forms the primary winding of the transformer, and if that particular phase fails or is lost, the power supply unit will not generate an electrical output voltage and will therefore lose its functionality.

[0018] Importantly, if the three phases are 120° phase-shifted relative to each other and if the three phases are coupled to the same transformer in the same manner, the total output voltage and / or total output current can sum to zero. In practice, for example, the total output voltage is the sum of the voltages induced by each of the three phases. Given a 120° phase shift relative to each other and equal voltage amplitudes, the total output voltage can therefore sum to zero.

[0019] In order to generate a non-zero root mean square (RMS) value of the electrical output voltage and / or the electrical output current with a 120° phase shift between the three phases, at least one of the three phases should be coupled to the transformer differently than the other two phases. For example, the winding direction and / or number of windings of the primary winding corresponding to one of the three phases can be different from those of the other two phases.

[0020] In particular, by using different winding directions for one of the three phases, the corresponding phase generates an output voltage in the secondary winding that has an additional 180° phase shift compared to the other two phases. Consequently, the sum of the output voltages induced in the secondary winding by the three phases has a non-zero RMS value. Alternatively or additionally, by using different winding numbers for the primary windings corresponding to the three phases, the sum of the output voltages induced in the secondary winding by the three phases has a non-zero RMS value. Advantageously, if the electrical input voltage and / or electrical input current of one or two of the three phases is zero, that is, if one or two of the three phases fails or is lost, the RMS value of the output voltage remains non-zero.

[0021] According to another embodiment of a power supply unit for a three-phase AC system, a transformer includes a secondary winding such that the magnetic flux passing through the secondary winding corresponds to the sum of the magnetic flux generated by the first primary winding, the second primary winding, and the third primary winding during operation of the power supply unit. In other words, the secondary winding of the transformer is simultaneously coupled to all three primary windings corresponding to the three phases. For example, the transformer includes a toroidal or circular core, and all three primary windings and the secondary winding are wound along the polar directions of the toroidal core. As another example, the transformer may include a shell-type core, and all primary and secondary windings are wound around the same central column of the shell-type core. The number of turns of the secondary winding can be selected so that the output voltage has a predetermined amplitude. The transformer may also include two or more secondary windings.

[0022] According to another embodiment of a power supply unit for a three-phase AC system, at least one of the primary windings is a half-turn winding. Herein and hereinafter, a half-turn winding has a number of turns equal to or approximately equal to half. For example, all primary windings are half-turn windings. For example, the transformer includes a toroidal core, and the three-phase conductor includes a substantially straight portion extending through a central aperture of the toroidal core in a direction parallel to the main axis of the toroidal core. In this case, the two different winding directions correspond to two opposite directions parallel to the main axis of the toroidal core.

[0023] According to another embodiment, the power supply unit further includes an electronic circuit configured to generate a constant DC output voltage from the transformer's output voltage. For example, the electronic circuit includes a rectifier configured to rectify the transformer's AC output voltage and generate the DC output voltage. Furthermore, the electronic circuit may include a voltage regulator configured to generate a constant DC output voltage that is independent of the amplitude of the transformer's AC output voltage, at least as long as the amplitude of the transformer's AC output voltage is within predetermined limits. For example, if the amplitude of the transformer's AC output voltage drops to half its nominal value, the DC output voltage of the electronic circuit remains constant. In this case, the DC output voltage of the electronic circuit advantageously remains constant even if one or two of the three input phases coupled to the transformer fail or are lost.

[0024] Furthermore, the present invention provides an electronic circuit breaker. In particular, the electronic circuit breaker includes the power supply unit described above. All features of the power supply unit of the electronic circuit breaker apply vice versa.

[0025] According to one embodiment, an electronic circuit breaker for use in a three-phase AC system includes a power supply unit as described above, wherein the power supply unit is configured to supply power to a trip unit of the electronic circuit breaker. For example, the trip unit is configured to monitor current flowing through the circuit breaker during operation. Furthermore, the trip unit can be configured to, for example, switch or brake current flowing through the circuit breaker during operation if the monitored current falls outside a predetermined range.

[0026] According to another embodiment of the electronic circuit breaker, the trip unit includes at least one current sensor for monitoring the current flowing through the circuit breaker. For example, the trip unit includes a separate current sensor for connection to each of the three phases of the circuit breaker. For example, a transformer may or may not be used as part of the power supply unit and for measuring the current flowing through the circuit breaker during operation.

[0027] According to another embodiment of the electronic circuit breaker, the current sensor is a Hall effect sensor. A Hall effect sensor is an indirect current sensor that detects the strength of the magnetic field generated by the current to be sensed. Alternatively or additionally, the current sensor may be a magnetoresistive current sensor, a fluxgate sensor, or a current sensor for direct current sensing, such as a resistor that generates a voltage drop proportional to the current to be sensed.

[0028] According to another embodiment, an electronic circuit breaker is configured as a protective switch for a three-phase AC motor. For example, the electronic circuit breaker is configured to protect the three-phase AC motor from short circuits or electrical overloads. For example, if the current carried by at least one of the three-phase conductors, as measured by the trip unit, is abnormal, the electronic circuit breaker electrically disconnects the motor from one or more of the three-phase conductors.

[0029] Further advantageous embodiments and further embodiments of the contactor device and of the method for operating a contactor device become apparent from the following exemplary embodiments which are described in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic perspective view of a power supply unit according to an exemplary embodiment is shown.

[0031] Figure 2 A schematic diagram of a power supply unit according to another exemplary embodiment is shown.

[0032] Figure 3 Shown is a schematic diagram depicting voltage variations over time during operation of a power supply unit according to an exemplary embodiment.

[0033] Figure 4 A schematic circuit diagram of an electronic circuit breaker according to an exemplary embodiment is shown. DETAILED DESCRIPTION

[0034] Elements that are identical, similar, or have the same effect are denoted by the same reference numerals in the figures. The figures and the proportions of the elements shown in the figures are not to be considered true to scale. On the contrary, individual elements may be shown enlarged for better representation and / or better understanding.

[0035] according to Figure 1 The power supply unit 1 of the exemplary embodiment includes a transformer 2 for use in a three-phase AC system. The transformer 2 includes a toroidal magnetic core 5, a first phase conductor L1 forming a first primary winding 31 of the transformer 2, a second phase conductor L2 forming a second primary winding 32 of the transformer 2, and a third phase conductor L3 forming a third primary winding 33 of the transformer 2. A secondary winding 4 is wound around the magnetic core 5 in a poloidal direction.

[0036] Each of the first, second, and third primary windings 31, 32, and 33 is formed as a half-turn winding. In other words, each of the first, second, and third phase conductors L1, L2, and L3 includes a straight or substantially straight portion that passes through the central hole of the annular core 5 in a direction parallel to the main axis of the annular core 5. During operation, the magnetic flux generated by these straight or substantially straight portions of the phase conductors L1, L2, and L3 is coupled to the secondary winding via the magnetic core 5.

[0037] The three-phase conductors L1, L2, L3 carry an alternating current during operation with a 120° phase shift between each pair of the three-phase conductors L1, L2, L3. To induce a non-zero voltage in the secondary winding 4, the winding direction of the third primary winding 33 is opposite to the winding direction of the first and second primary windings 31, 32.

[0038] according to Figure 2 A power supply unit 1 according to another exemplary embodiment includes a transformer 2 for use in a three-phase AC system. Figure 1 Compared to the exemplary embodiment described above, the first, second, and third primary windings 31, 32, 33 each include multiple turns wound around the magnetic core 5. The number of turns in each of the three primary windings 31, 32, 33 is equal. The winding direction of the first and second primary windings 31, 32 is clockwise, while the winding direction of the third primary winding 33 is counterclockwise. Therefore, the voltage induced in the secondary winding 4 by the third primary winding 33 has an additional 180° phase shift. Therefore, during operation of the transformer 2, the output voltage V4 of the transformer 2 at least approximately follows the following relationship:

[0039]

[0040] Wherein, V31 , V32 and V33 represent the input voltages of the first primary winding, the second primary winding and the third primary winding respectively, Np represents the number of turns of each primary winding, and Ns represents the number of turns of the secondary winding 4 .

[0041] In an alternative exemplary embodiment, the transformer 2 has Figure 2 The same form is shown, but the number of turns of each of the three primary windings 31, 32, 33 is different, while the winding direction of these three primary windings is the same.

[0042] Figure 3 The diagram in FIG. 2 schematically shows the operation of the transformer 2 during Figure 2 The voltages shown in FIG vary with time t. Specifically, the AC input voltages V31, V32, and V33 applied to the three primary windings 31, 32, and 33, respectively, have equal amplitudes and are 120° phase-shifted relative to each other. The output voltage V4 of transformer 2 is given by Equation 1 above and is described here for an equal number of turns Np=Ns in the primary and secondary windings. Specifically, because the third primary winding 33 has an opposite winding direction compared to the first and second primary windings 31 and 32, the sum of the output voltages V4 is a non-zero RMS value.

[0043] according to Figure 4In the exemplary embodiment shown, an electronic circuit breaker 10 for a three-phase AC system includes a power supply unit 1, three switches 13, and a trip unit 11 having three current sensors 12. The power supply unit 1 includes a combination of Figure 1 or Figure 2 Transformer 2 described.

[0044] The three primary windings 31, 32, 33 of the transformer 2 are electrically connected to the three-phase conductors L1, L2, L3, respectively. In addition, the three switches 13 are operated by the trip unit 11 and are configured to disconnect the three-phase conductors L1, L2, L3, respectively, if the trip unit 11 detects a short circuit or an electrical overload.

[0045] The power supply unit 1 comprises an electronic circuit 6 configured to convert the output voltage V4 of the transformer 2 into a constant DC output voltage. The output voltage of the electronic circuit 6 remains constant even if one or two of the three-phase conductors L1, L2, L3 fail or are lost during operation.

[0046] Power supply unit 1 provides power for operating trip unit 11. Trip unit 11 includes three current sensors 12 in the form of Hall sensors that are configured to measure the current flowing through the three-phase conductors L1, L2, and L3 during operation. Trip unit 11 monitors the current during operation and opens one or all switches 13 if a short circuit or overload is detected.

[0047] The present invention is not limited to the exemplary embodiments by the description based on the exemplary embodiments. Rather, the present invention includes any novel feature and any combination of features, in particular any combination of features in the patent claims and any combination of features in the exemplary embodiments, even if the feature or the combination itself is not explicitly stated in the patent claims or the exemplary embodiments.

[0048] Reference numerals

[0049] 1 Power supply unit

[0050] 2 Transformers

[0051] 31 First primary winding

[0052] 32 Second primary winding

[0053] 33 Third primary winding

[0054] 4 Secondary Windings

[0055] 5 Magnetic core

[0056] 6 Electronic Circuits

[0057] 10 Electronic circuit breakers

[0058] 11 Trip unit

[0059] 12 Current sensor

[0060] 13 Switch

[0061] L1 First phase conductor

[0062] L2 Second phase conductor

[0063] L3 Third phase conductor

[0064] V31 First primary voltage

[0065] V32 Second primary voltage

[0066] V33 Third primary voltage

[0067] V4 output voltage

[0068] t time

Claims

1. A power supply unit (1) for use in a three-phase AC system, comprising: Transformer (2); as well as A first phase conductor (L1), a second phase conductor (L2) and a third phase conductor (L3) form a first primary winding, a second primary winding and a third primary winding (31, 32, 33) of the transformer (2), respectively, wherein The AC voltage and / or AC current between each pair of the first phase conductor (L1), the second phase conductor (L2) and the third phase conductor (L3) are 120° out of phase, The winding direction of the third primary winding (33) is opposite to the winding direction of the first primary winding and the second primary winding (31, 32), and / or The number of windings of the third primary winding (33) is different from the number of windings of the first primary winding (31) or the second primary winding (32).

2. The power supply unit (1) according to the preceding claim, wherein The transformer (2) comprises a secondary winding (4) such that a magnetic flux passing through the secondary winding (4) corresponds to the sum of the magnetic fluxes generated by the first, second and third primary windings (31, 32, 33) during operation of the power supply unit (1).

3. The power supply unit (1) according to any one of the preceding claims, in, At least one of the primary windings (31, 32, 33) is a half-turn winding.

4. The power supply unit (1) according to any one of the preceding claims, Also included is an electronic circuit (6) configured to generate a constant DC voltage from the output voltage (V4) of the transformer (2).

5. An electronic circuit breaker (10) for a three-phase AC system, comprising a power supply unit (1) according to any one of claims 1 to 3, wherein: The power supply unit (1) is configured to supply power to a trip unit (11) of the electronic circuit breaker (10).

6. Electronic circuit breaker (10) according to the preceding claim, wherein The trip unit (11) includes at least one current sensor (12) for monitoring the current flowing through the circuit breaker (10).

7. Electronic circuit breaker (10) according to the preceding claim, wherein The current sensor (12) is a Hall sensor.

8. The electronic circuit breaker (10) according to any one of claims 5 to 7, wherein: The electronic circuit breaker (10) is configured as a protection switch for a three-phase AC motor.

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