Circuit arrangement and method thereof

Abstract

The invention relates to the operation of the intermediate circuit processing while reducing the harmonic components in the input current, i.e. to the availability or applicability in different power supply networks, in particular in single-phase and three-phase networks with the same circuit topology or in the case of a phase fault.

Description

Technical Field

[0001] This invention relates to efficient, network-type-independent intermediate circuit processing that reduces harmonic components in the input current, i.e., its availability or applicability in different power supply networks, particularly in single-phase and three-phase networks with the same circuit topology. Specifically, a 3-phase PFC topology is configured to be adaptable to control so that it can also be used with 1-phase power supply connections having the same output power. It should be noted that harmonic components on the power supply side must be kept at a low level. Background Technology

[0002] Different concepts are known from existing technologies for implementing intermediate circuit processing for different types of power supply networks.

[0003] For example, a multiphase rectifier bridge circuit for single-phase input is known from EP0696838B1.

[0004] A motor drive power conversion system is known from EP3509212A1, comprising a filter circuit with a single inductor and capacitors for each input phase, an active rectifier with silicon carbide rectifier switching devices, a DC intermediate circuit with thin-film DC intermediate circuit capacitors, an inverter, and a controller, thereby operating the rectifier switching devices at a PWM rectifier switching frequency.

[0005] The Vienna rectifier offers an alternative solution known and widely used in the prior art. Compared to the conventional six-pulse bridge circuit (B6) using 3-phase current, the Vienna rectifier is characterized by a significant reduction in harmonic components on the AC voltage side, even providing a DC voltage that is twice the AC voltage. Because the current curve is almost sinusoidal, a smaller power supply filter is required, especially for higher power applications, thus necessitating a smaller rectifier size.

[0006] However, the object of the present invention is to construct a 3-phase PFC topology that can be adapted to control so that the topology can also be used for 1-phase power connections.

[0007] This approach is known from the public DE102019131410A, and can be operated on the power supply phase using a 3-phase Vienna rectifier.

[0008] The disadvantages of Vienna rectifiers are their cost and the complexity and necessity of the electronic control circuitry used to control them with pulse width modulation (PWM).

[0009] However, various systems known in the prior art exhibit at least one of the following drawbacks or problems that need to be improved or eliminated:

[0010] a) The harmonic content of the input current is too high;

[0011] b) Cannot handle intermediate circuit voltages independently of network type;

[0012] c) Loads with unbalanced power supply phases;

[0013] d) It is impossible to reduce electronic changes (Elektronikvarianz);

[0014] e) High tooling and / or development costs in design and manufacture;

[0015] f) High storage costs due to various variants. Summary of the Invention

[0016] Therefore, the purpose of this invention is to overcome the above-mentioned disadvantages and create a solution that can be produced inexpensively. This solution enables effective intermediate circuit processing, particularly reducing harmonic components in the input current. It is also applicable to 3-phase and 1-phase operation, or can operate in the event of a phase fault without significant harmonics on the power supply side.

[0017] This objective is achieved by combining the features described below.

[0018] The basic concept is as follows: three power supply phases L1, L2, and L3 can be connected to a 3-phase PFC topology for 3-phase operation. Each of the 3-phase PFC topologies operates in single-phase mode and has a 3-phase rectifier circuit, supplemented by switches for activating and deactivating one or more phases L1, L2, and L3, and two other independently controllable switches. For single-phase PFC operation, the corresponding switches in each phase are opened or closed in a controlled manner to regulate the current on the two active phases in a sinusoidal manner and in phase with the power supply.

[0019] The core idea is that the concept according to the invention allows for the integration of circuit layouts, such as Minnesota rectifiers, with operation in the event of phase failure.

[0020] Another relevant aspect is that the switching between single-phase and three-phase operation is also activated in the event of a power failure or phase failure, so the circuit can be used for this purpose.

[0021] According to the present invention, a circuit device is provided for this purpose having a 3-phase PFC stage having three connection terminals for terminals of phases L1, L2, L3 for 3-phase operation, conventionally designed and operating in single-phase operation by bridging the intermediate circuit of the 3-phase rectifier circuit and the rectifier diode bridge (including the rectifier diodes) via a switching device consisting of two diodes, each diode being switched on by an independently controllable switch "S1, S2", wherein phases L1, L2, L3 converge at a star junction via their respective line paths, and wherein a bidirectional switch for activating and deactivating the relevant phase is provided in each line path at the star junction, and wherein for single-phase PFC operation, the corresponding switch in the phase is opened or closed in a controlled manner to regulate the current on the two active phases in a sinusoidal manner and in phase with the power supply.

[0022] In a preferred embodiment, it is specified that in single-phase PFC operation, only two of the three phases, preferably phases L1 and L2, are turned on or connected.

[0023] Another advantage is that, in addition to the main intermediate circuit capacitor, the intermediate circuit also has a capacitor that can be switched on. Since small intermediate circuit capacitors are advantageously used in 3-phase operation, switching on a second intermediate circuit capacitor may be advantageous when extending to single-phase operation, thereby increasing the circuit's potential output power while limiting voltage ripple in the intermediate circuit.

[0024] In another preferred embodiment of the invention, an inductor is provided between the star junction of the phase and the center tap of the switch of the switching device. Advantageously, an inductor is also provided between the switch of the circuit device and the rectifier diodes of the rectifier diode bridge.

[0025] In a preferred embodiment, the switch of the switching device is specified to have a diode of a second switch whose conduction direction is away from the switching device, and the second switch has a diode whose conduction direction is away from the first switch. Preferably, the center tap connected to the star junction of the three phases L1, L2, L3 is located between the diode whose conduction direction is away from the first switch and the diode whose conduction direction is away from the second switch.

[0026] Another aspect of the invention relates to a method for operating the 3-phase circuit device described above in single-phase PFC operation, wherein when a positive power supply half-wave is applied to phase L1, a switch in the corresponding line path is closed, and then by turning on the second switch, an increased current is generated from the junction of the phase through the corresponding rectifier diode to the junction of the phase, and then by turning off the second switch, the current flows through the diode in the first switch (of the switching device) or through the (reverse) switching switch into the intermediate circuit and returns to the corresponding rectifier diode of the rectifier diode bridge via ground, thereby reaching the junction of the second (additionally connected) phase.

[0027] For the negative power supply half-wave, this can also be done in a similar manner. When the negative power supply half-wave is applied to the second (additionally connected) phase, the switch in the corresponding line path in that phase is closed, and then by turning on the second switch of the switching device, an increased current is generated from the junction of the second connected phase L2 through the corresponding rectifier diode to the junction of the first phase L1. Then, by turning off the second switch, this current flows through the diode in the first switch (of the circuit device) or through the (reverse) switching switch into the intermediate circuit and returns to the corresponding rectifier diode of the rectifier diode bridge via its ground, thereby reaching the junction of the first phase.

[0028] Advantageously, before switching one or more switches, the current at the phase L2 connector is first adjusted to a predefined value, which can also be zero.

[0029] In another advantageous embodiment of the invention, one or more switches (in the circuit path) are timed at the power supply frequency, while advantageously, the switches (of the circuit device) are timed at a frequency significantly higher than the power supply frequency, in particular, the switches are timed by pulse width modulation in the frequency range between 20 kHz and 150 kHz.

[0030] In order for the circuit according to the invention to also operate in three-phase mode, it is necessary to use a constant power three-phase operating power consumer, wherein the power can be constant or the consumer can be a resistor during single-phase operation. Attached Figure Description

[0031] Other advantageous further aspects of the invention are characterized above or presented in more detail below together with the description of preferred embodiments of the invention with reference to the accompanying drawings.

[0032] The attached diagram shows:

[0033] Figure 1 A circuit topology for implementing single-phase operation of a 3-phase PFC stage according to the present invention is shown;

[0034] Figure 2 The first embodiment of the bidirectional switch to the star junction is shown in the phase line path.

[0035] Figure 3 An alternative implementation scheme for the bidirectional switch to the star junction in the phase line path is shown. Detailed Implementation

[0036] The invention will now be explained in more detail with reference to the accompanying drawings, in which the same reference numerals denote the same structural and / or functional features in exemplary embodiments.

[0037] Figure 1 An exemplary circuit arrangement 1 according to the concept of the present invention is shown. Circuit arrangement 1 has a 3-phase PFC stage having three connection terminals for terminals L1, L2, and L3 for three-phase operation. For single-phase operation, the power consumption causes the power supply voltage to be applied only to terminals L1 and L2 (e.g., ...). Figure 1 As shown), the third phase L3 is idle or disconnected from the power supply.

[0038] Circuit device 1 includes an intermediate circuit 20 and a rectifier diode bridge 10 with six rectifier diodes. Furthermore, a switching device 30 is connected in parallel with the intermediate circuit 20. This switching device 30 consists of two switches S1 and S2 and diodes connected in parallel with them, the diodes arranged in series with opposite conduction directions. The two switches S1 and S2 can be implemented using known techniques, but it is important that they are inherently present within the semiconductor housing or exist externally as reverse-biased diodes. The two switches S1 and S2 are independently controllable switches and are timed using pulse width modulation at a frequency much higher than the power supply frequency to regulate the current.

[0039] exist Figure 1 It can also be seen that phases L1, L2, and L3 converge at star junction 11 through their respective line paths, and bidirectional switches S3, S4, and S5 are arranged in each of the three line paths. They are timed according to the power supply frequency to activate and deactivate phases L1 and L2 at star junction 11.

[0040] In addition to the main intermediate circuit capacitor C1, the intermediate circuit 20 also has a capacitor C2 that can be switched on and is connected in parallel with capacitor C1.

[0041] Inductors Lb1 and Lb2, as shown, are also provided.

[0042] Figure 2 and Figure 3An embodiment of bidirectional switches S3, S4, and S5 in the line paths of phases L1, L2, and L3 to star junction 11 is shown. Switches S3, S4, and S5 are designed as bidirectional switches. They can be implemented using IGBTs and MOSFETs.

[0043] With the positive half-wave power supply in operation, switch S3 closes through this half-wave, and after switch S2 is turned on, an increased current is generated as follows: from the phase junction of L1 via S3, Lb2, through switch S2 and the rectifier diode to the phase junction of L2. When switch S2 is turned off, this current flows through the diode in switch S1 or through the reverse-biased switch into the intermediate circuit (current: L1-S3-Lb2-S1-C1-rectifier diode-L2).

[0044] In the case of a negative power supply half-wave, its behavior is the same as that in the case of a positive power supply voltage, except that the sign of the power supply current is reversed.

[0045] When switch S2 is turned on: current L2-S4-Lb2-S2-rectifier diode-L1, and when switch S2 is turned off: current L2-S4-Lb2-S1-C1-rectifier diode-L1.

[0046] The implementation of this invention is not limited to the preferred exemplary embodiments given above. Rather, even in cases of fundamentally different designs, various variations of the illustrated scheme are conceivable.

Claims

1. A circuit device (1) having a three-phase PFC stage, having three connection terminals for connecting the phases (L1, L2, L3) of three-phase operation, and operating in single-phase operation by bridging between the intermediate circuit (20) of a three-phase rectifier circuit and a rectifier diode bridge (10) having rectifier diodes via a switching device (30) consisting of two diodes, each diode being connected to an independently controllable switch, wherein the three phases (L1, L2, L3) converge at a star junction (11) via their respective line paths, and wherein a bidirectional switch for activating and deactivating each phase (L1, L2, L3) is provided in each line path at the star junction (11), and wherein for single-phase PFC operation, the corresponding bidirectional switch in the phase is opened or closed in a controlled manner to regulate the current on the two active phases in a sinusoidal manner and in phase with the power supply. The intermediate circuit (20) includes, in addition to the main intermediate circuit capacitor (C1), a capacitor (C2) that can be switched on, and... Before switching one or more of the bidirectional switches, the current at the second phase (L2) terminal of the three phases is first adjusted to a predefined value, which includes zero.

2. The circuit device (1) according to claim 1, characterized in that, In single-phase PFC operation, only two of the three phases are turned on or connected.

3. The circuit device (1) according to claim 1 or 2, characterized in that, The inductor (Lb2) is connected between the star junction (11) of the three phases (L1, L2, L3) and the center tap between the switch.

4. The circuit device (1) according to claim 1 or 2, characterized in that, The inductor (Lb1) is connected between the first switch in the switch of the switching device (30) and the rectifier diode of the rectifier diode bridge (10).

5. The circuit device (1) according to claim 1 or 2, characterized in that, The first switch in the switch has a diode whose conduction direction is away from the second switch in the switch, the second switch has a diode whose conduction direction is away from the first switch, and the center tap (M) connected to the star junction (11) is located between the diode whose conduction direction is away from the second switch and the diode whose conduction direction is away from the first switch.

6. A method for operating the circuit device (1) according to any one of claims 1 to 5 in single-phase PFC operation, wherein when a positive power supply half-wave is applied to the first phase (L1) of the three phases, a first bidirectional switch in the corresponding line path is closed, and then by turning on a second switch in the switch device (30), an increased current is generated from the junction of the first phase (L1) through the first bidirectional switch through the corresponding rectifier diode to the junction of the second phase (L2), and then by turning off the second switch, the current flows through the diode in the first switch in the switch or through the reverse switching into the intermediate circuit (20) and returns to the corresponding rectifier diode of the rectifier diode bridge (10) via its ground, thereby reaching the junction of the second phase (L2).

7. According to the method of claim 6, when a positive power supply half-wave is applied to the second phase (L2), the second bidirectional switch in the corresponding line path is closed, and then by turning on the second switch of the switching device (30), an increased current is generated from the junction of the second phase (L2) through the second bidirectional switch to the junction of the first phase (L1) through the corresponding rectifier diode, and then by turning off the second switch, the current flows through the diode in the first switch or through the reverse switching switch into the intermediate circuit (20) and returns to the corresponding rectifier diode of the rectifier diode bridge (10) through its ground, thereby reaching the junction of the first phase (L1).

8. The method of claim 6 or 7, wherein one or more of the bidirectional switches are timed at a power supply frequency.

9. The method of claim 6 or 7, wherein the switch is timed at a frequency significantly higher than the power supply frequency.

10. The method of claim 9, wherein the switch is timed using pulse width modulation in a frequency range between 20 kHz and 150 kHz.

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