Method and control circuit for operating power converter arrangement and power converter arrangement

Abstract

A method for operating a power converter device, a controller for controlling operation of a power converter device, and a power converter device are disclosed. The method includes operating the power converter device in a first mode of operation. The power converter apparatus includes: a first power converter including input nodes each configured to receive a respective one of the input voltages, the input voltages each referencing a first ground node, and the first power converter configured to provide a first intermediate voltage and a second intermediate voltage each referencing a second ground node; and a second power converter connected between the first power converter and an output of the power converter arrangement. Operating the power converter apparatus in the first mode of operation includes adjusting an input power received by the first power converter from an input node in accordance with an output signal and in accordance with a ground signal, and adjusting each of the first intermediate voltage and the second intermediate voltage by the second power converter.

Description

Technical Field

[0001] The present disclosure generally relates to methods for operating a power converter device, particularly a power converter device that can be used to charge a battery, such as a battery of an electric vehicle (EV). The present disclosure also relates to a control circuit for operating a power converter device and a power converter device. Background Art

[0002] A power converter device for charging a battery may include a first power converter connected to a power grid and a second power converter connected between the first power converter and the battery. The first power converter may be implemented as an AC-DC converter that generates an intermediate voltage (DC link voltage) based on an AC input voltage received from the power grid. The second power converter generates a regulated output current or a regulated output voltage based on the DC link voltage to power the battery. The second power converter typically provides galvanic isolation between the first power converter and the power grid on one side and the battery on the other side. With this galvanic isolation, the voltage provided to the battery is referenced to a fixed potential that is separate from the ground potential referenced to the AC input voltage. In this way, current from the battery to ground can be avoided.

[0003] A transformer may be used to achieve galvanic isolation. However, transformers are expensive and contribute significantly to the overall size of the second power converter. Therefore, it is desirable to implement the second power converter without galvanic isolation.

[0004] In addition, the first power converter may include several converter stages, wherein each converter stage is connected to a corresponding input node to receive a corresponding AC input voltage from the power grid. A power converter connected to a three-phase power grid, for example, includes three converter stages. Each converter stage typically includes at least one electronic switch operated in a switching mode (pulse width modulation (PWM) mode). In certain operating scenarios of the power converter device, the first power converter may be operated in a simplified switching mode. This includes deactivating each converter stage except one of the converter stages in the converter stage. Deactivating the converter stage reduces the power consumption required to operate the first power converter, and thus improves the efficiency of the power converter device.

[0005] There is a need to operate a power converter arrangement having a first converter and a second converter in an efficient manner, wherein the second power converter has no galvanic isolation. Summary of the invention

[0006] One example relates to a method. The method includes operating a power converter device in a first operating mode. The power converter device includes a first power converter and a second power converter. The first power converter includes input nodes each configured to receive a corresponding one of the input voltages, the input voltages each being referenced to a first ground node, and the first power converter is configured to provide a first intermediate voltage and a second intermediate voltage each being referenced to a second ground node. The second power converter is connected between the first power converter and an output terminal of the power converter device. Operating the power converter device in the first operating mode includes: adjusting an input power received by the first power converter from the input node according to an output signal and according to a ground signal, and adjusting each of the first intermediate voltage and the second intermediate voltage by the second power converter. The ground signal is a signal between the first ground node and the second ground node. Adjusting the input power received by the first power converter includes: obtaining a switching node voltage reference based on the output signal and the ground signal, adjusting the first intermediate voltage includes: selecting a maximum switching node voltage reference among the obtained switching node voltage references, and adjusting the first intermediate voltage so that the first intermediate voltage tracks the maximum switching node voltage reference among the obtained switching node voltage references, and adjusting the second intermediate voltage includes: selecting a minimum switching node voltage reference among the obtained switching node voltage references, and adjusting the second intermediate voltage so that the second intermediate voltage tracks the minimum switching node voltage reference among the obtained switching node voltage references.

[0007] Another example relates to a controller configured to operate a power converter arrangement according to the method. Yet another example relates to a power converter arrangement. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The following examples are explained with reference to the accompanying drawings. The accompanying drawings are used to illustrate certain principles and therefore only show aspects necessary for understanding these principles. The accompanying drawings are not drawn to scale. The same reference numerals in the accompanying drawings represent similar features.

[0009] Figure 1 An example of a power converter apparatus is shown, the power converter apparatus comprising: a first power converter configured to receive an input voltage referenced to a first ground node, a second power converter connected between the first power converter and an output terminal, and a control circuit for controlling operation of the first power converter and the second power converter;

[0010] Figure 2 a signal diagram showing an example of an input voltage that may be received by a first power converter;

[0011] Figure 3 Shows the operation Figure 1 An example of a method of a power converter arrangement of the type shown;

[0012] Figure 4 Shows Figure 1 A power converter device of the type shown, wherein Figure 4 A more detailed example of a first power converter and a second power converter, each comprising a number of converter stages, is shown;

[0013] Figure 5 and Figure 6 Various examples of one converter stage of a first power converter are shown;

[0014] Fig. 7A and Figure 7B An example of a bidirectional blocking electronic switch is shown;

[0015] Figure 8 An example of an inductor and filter arrangement is shown;

[0016] Fig. 9 An example of a first converter stage and a second converter stage of a second power converter is shown;

[0017] Fig.10 shows a block diagram of a control circuit according to one example;

[0018] Fig.11 Shown included in the Fig.10 An example of an output signal controller in a control circuit;

[0019] Fig.12 Shown included in the Fig.10 Examples of ground signal controllers and input current controllers in a control circuit;

[0020] Fig.13 Shown included in the Fig.10 An example of a first intermediate voltage reference controller and a second intermediate voltage reference controller in a control circuit of;

[0021] Fig.14 Shown included in the Fig.10 An example of a first intermediate voltage controller and a second intermediate voltage controller in a control circuit of;

[0022] Fig.15 showing a signal diagram illustrating operation of a power converter arrangement in a first operating mode;

[0023] Fig.16 showing a signal diagram illustrating operation of a power converter arrangement in a second operating mode; and

[0024] Fig.17 A signal diagram illustrating operation of a power converter in a transition phase between a first mode of operation and a second mode of operation is shown. DETAILED DESCRIPTION

[0025] In the following detailed description, reference is made to the accompanying drawings. The accompanying drawings form part of the specification and, for illustrative purposes, show examples of how the invention may be used and implemented. It should be understood that the features of the various embodiments described herein may be combined with each other unless otherwise specifically noted.

[0026] Figure 1 An example of a power converter device including a first power converter 1 and a second power converter 2 is shown. The first power converter 1 includes a plurality of input nodes a, b, c, wherein each input node a, b, c is configured to receive a corresponding one of a plurality of input voltages Va, Vb, Vc. The input voltages Va, Vb, Vc are referenced to a first reference node n, which is also referred to as a first ground node n hereinafter. In addition, the first power converter 1 is configured to provide a first intermediate voltage Vx and a second intermediate voltage Vz, wherein each of the first intermediate voltage Vx and the second intermediate voltage Vz is referenced to a second reference node y, which is also referred to as a second ground node y hereinafter. The first intermediate voltage Vx is a voltage between the first intermediate node x and the second ground node y, and the second intermediate voltage Vz is a voltage between the second intermediate node z and the second ground node y. According to an example, the first intermediate voltage Vx is a positive voltage referenced to the second ground node y, and the second intermediate voltage Vz is a negative voltage referenced to the second ground node y. In this case, the voltage between the first intermediate node x and the second intermediate node z is positive. Hereinafter, the first and second intermediate voltages Vx and Vz are also referred to as first and second DC link voltages Vx and Vz, and the first and second intermediate nodes x and z are also referred to as first and second DC link nodes x and z.

[0027] According to an example, the plurality of input nodes a, b, c comprises three input nodes a, b, c, such that the power converter arrangement is configured to receive three input voltages Va, Vb, Vc from a three-phase grid.

[0028] The second power converter 2 is connected between the first power converter 1 and the output terminals p, r of the power converter device. More specifically, the second power converter 2 is connected between the first DC link node x and the second DC link node z on one side and the first output node p and the second output node r on the other side. The output nodes p, r are configured to have a load Z connected thereto (at Figure 1 During operation of the power converter device, an output voltage Vout is available between the output nodes p, r, and the power converter device supplies an output current Iout to a load Z at the output nodes p, r.

[0029] According to one example, the power converter device is configured to adjust at least one of the output voltage Vout and the output current Iout. The load Z can be a battery charged by the power converter device. In this example, the voltage level of the output voltage Vout is defined by the load Z, and the output current Iout can be adjusted by the power converter device so that the output current Iout meets the predefined output current reference (output current set point). However, this is only an example. According to another example, the power converter device is configured to adjust the output voltage Vout.

[0030] Reference Figure 1 The power converter device further comprises a control circuit 3. The control circuit 3 is configured to control the operation of the first power converter 1 and the second power converter 2. Figure 1 In FIG. 1 , this is schematically shown as the control circuit 3 providing a first control signal S1 to the first power converter 1 and a second control signal S2 to the second power converter 2. The first control signal S1 represents one or more control signals required to control the operation of the first power converter 1. Equivalently, the second control signal S2 represents one or more control signals required to control the operation of the second power converter 2.

[0031] According to an example, the first power converter 1 is a PFC (Power Factor Correction) converter configured to receive an AC input voltage Va, Vb, Vc such as a grid voltage, and provide first and second DC voltages as first and second DC link voltages Vx and Vz.

[0032] According to an example, Figure 2 As shown, each of the three input voltages Va, Vb, and Vc is a sinusoidal input voltage. Figure 2 The signal diagram shows three sinusoidal input voltages that can be received from a three-phase grid during one cycle of the input voltages Va, Vb, Vc. The input voltages Va, Vb, Vc have the same frequency and RMS (root mean square) value. For example, the frequency is 50 Hz or 60 Hz, and the RMS value is 230 V. RMS or 110V RMS The input voltages Va, Vb, Vc differ in having different phase angles. According to one example, the phase shift between each pair of the input voltages Va, Vb, Vc is 120° (2π / 3).

[0033] The load Z may be coupled to the first ground node n. Such coupling may include capacitive coupling or a direct (current) connection. Such coupling between the load Z and the first ground node n may result in a current flow between the load Z and the first ground node n. This is undesirable because such a current flow may cause a protective device (such as an RCD (residual current detection) device) to trip and disable the power converter device. Therefore, appropriate measures are required to prevent such a current flow between the load Z and the first ground node n.

[0034] A conventional way to avoid such current flow is to provide galvanic isolation between input nodes a, b, c (where input voltages Va, Vb, Vc referenced to a first ground node n are available) and output nodes p, r for connecting a load Z thereto. Galvanic isolation can be achieved using a transformer. However, transformers are expensive and contribute significantly to the overall size of the power converter device.

[0035] Therefore, according to Figure 1 The power converter arrangement of the invention has no galvanic isolation between the input nodes a, b, c and the output nodes p, r. In particular, the second power converter 2 has no galvanic isolation between the first intermediate node x and the second intermediate node z and the output nodes p, r.

[0036] The first power converter 1 is a switch mode converter. This includes: the first power converter 1 includes a number of switches, each of which is configured to operate in a switch mode. Operating the electronic switch in the switch mode may include operating the electronic switch in a plurality of consecutive drive cycles, and in each drive cycle, operating the electronic switch in an on state (switch on state) during the on time and operating the electronic switch in an off state (switch off state) during the off time, so that the electronic switch is turned on and off in each drive cycle. For example, the switching frequency fs as the reciprocal of the duration Ts of a drive cycle is between several 10kHz and several 100kHz. Turning on and off the electronic switch requires energy. The losses associated with turning on and off the electronic switch are generally referred to as switching losses. The switching losses of a power converter having several electronic switches increase with the increase in the number of electronic switches. In addition, the switching losses increase with the increase in the switching frequency. Therefore, it is desirable to operate the first power converter 1 with reduced switching losses.

[0037] Figure 3 shows the operation according to Figure 1 An example of a method for a power converter device of the present invention is provided, which enables the first power converter 1 to operate with reduced switching losses and avoids current flow between the load Z and the first ground node n despite the lack of galvanic isolation. Figure 3, the method includes operating a power converter device (100) having a first power converter and a second power converter in a first operating mode. Operating the power converter device in the first operating mode includes: adjusting the input power received by the first power converter from the input node according to the output signal and according to the ground signal (110), and adjusting each of the first intermediate voltage and the second intermediate voltage by the second power converter (120). In addition, adjusting the input power received by the first power converter includes obtaining a switch node voltage reference (111) according to the output signal and the ground signal, and adjusting each of the first intermediate voltage and the second intermediate voltage by the second power converter includes: selecting a maximum switch node voltage reference from the obtained switch node voltage references and adjusting the first intermediate voltage so that the first intermediate voltage tracks the maximum switch node voltage reference (121), and selecting a minimum switch node voltage reference from the obtained switch node voltage references and adjusting the second intermediate voltage so that the second intermediate voltage tracks the minimum switch node voltage reference (122). Reference Figure 1 The method is described in more detail with reference to the power converter arrangement shown in FIG.

[0038] Reference Figure 1 , adjusting the input power received by the first power converter 1 from the input nodes a, b, c according to the output signal and according to the ground signal includes: the control circuit 3 controls the operation of the first power converter 1 according to the output signal and according to the ground signal. To this end, the control circuit 3 receives the measured output signal Sout' and the measured ground signal Syn'. The measured output signal Sout' represents the output signal of the power converter device to be adjusted. Therefore, the measured output signal Sout' represents the output current Iout when the output current Iout is to be adjusted, or represents the output voltage Vout when the output voltage Vout is to be adjusted. It can be achieved by using a conventional current or voltage measurement circuit ( Figure 1 The output signal is measured by a controller (not shown) to obtain a measured output signal Sout'. According to an example, the measured output signal Sout' is proportional to the output signal Sout to be regulated.

[0039] The ground signal Syn is a signal between the first ground node n and the second ground node y. The ground signal Syn is a voltage Vyn between the first ground node n and the second ground node y or a current Iyn between the first ground node n and the second ground node y. According to an example, Figure 1As shown by the dashed line in the figure, the first ground node y is ohmically connected to the second ground node n. In this example, the ground signal Syn is a voltage Vyn or a current Iyn. According to another example, the first ground node y is non-ohmically connected to the second ground node n. In this example, the ground signal Syn is a voltage Vyn between the first ground node n and the second ground node y. "Non-ohmically connected" includes, for example, that the first ground node n and the second ground node y are not connected at all or that the first ground node n and the second ground node y are capacitively coupled.

[0040] By adjusting the input power of the first power converter 1 according to the measured output signal Sout' and according to the measured ground signal Syn', both the output signal Sout and the ground signal Syn can be adjusted. Adjusting the output signal Sout includes adjusting the output signal so that the output signal is at least approximately equal to a predefined output signal reference (output signal set point). In addition, adjusting the ground signal Syn includes adjusting the ground signal Syn so that the ground signal is at least approximately equal to a predefined ground signal reference Syn* (ground signal set point). According to an example, the ground signal reference Syn* is zero, so that the ground voltage Vyn between the first ground node n and the second ground node y is zero, or when the first ground node n is connected to the second ground node y, the ground current Iyn between the first ground node n and the second ground node y is zero. In this case, the second power converter 2 can be implemented without current isolation without taking the risk of current flow between the load Z and the first ground node n.

[0041] The input power Pin of the first power converter 1 is the power received by the first power converter 1 at the input nodes a, b, c. The input power received at one of the input nodes a, b, c is given by the input voltage Va, Vb, Vc multiplied by the current Ia, Ib, Ic received at the corresponding input node, so the total input power is given by the sum of the input powers received at the corresponding input nodes a, b, c.

[0042] Pin=Va·Ia+Vb·Ib+Vc·Ic (1).

[0043] The voltage levels of the input voltages Va, Vb, Vc received at the respective input nodes a, b, c are defined by a power source (such as a power grid) providing the input voltages Va, Vb, Vc. Therefore, the input power received at each of the input nodes a, b, c can be adjusted by adjusting the current level of the respective input currents Ia, Ib, Ic.

[0044] Adjusting the current level of the input currents Ia, Ib, Ic includes adjusting the voltages Va\, Vb\, Vc\ at the switch nodes a\, b\, c\ of the first power converter 1. These voltages referenced to the second ground node y are referred to as switch node voltages Va\, Vb\, Vc\ hereinafter. The switch node voltage references Va\*, Vb\*, Vc\* are the desired voltage levels of these switch node voltages Va\, Vb\, Vc\. It should be noted that in the steady state of the power converter device, the potential at the second ground node y is at least approximately equal to the potential at the first ground node n, and therefore the switch node voltages Va\, Vb\, Vc\ can also be considered to be referenced to the first ground node n.

[0045] Reference Figure 1 , the first power converter 1 includes a plurality of switch nodes a\, b\, c\, wherein each of the switch nodes a\, b\, c\ is coupled to a corresponding one of the input nodes a, b, c. According to one example, each of the switch nodes a\, b\, c\ is inductively coupled to a corresponding input node a, b, c. This will be further described in detail below. In addition, each of the switch nodes a\, b\, c\ is coupled to each of the first intermediate node x and the second intermediate node z and the second ground node y. An example for coupling the switch nodes a\, b\, c\ to the first intermediate node x and the second intermediate node z and the second ground node y is further described in detail herein below.

[0046] As further detailed herein below, the switch node voltage Va\, Vb\, Vc\ at each switch node a\, b\, c\ can be adjusted by switching the corresponding switch node a\, b\, c\ between the second ground node y and one of the first intermediate node x and the second intermediate node z. Such switching is part of the switch mode operation of the first power converter 1 and is associated with switching losses.

[0047] When the first intermediate voltage Vx is adjusted by the second power converter 2 so that the first intermediate voltage Vx is equal to the first switch node voltage reference among the switch node voltage references Va\*, Vb\*, Vc\*, one of the switch nodes a\, b\, c\ having the first switch node voltage reference as its voltage reference can be permanently connected to the first intermediate node x, so that no switching operation is required to adjust the corresponding switch node voltage. For example, the first switch node voltage reference among the switch node voltage references Va\*, Vb\*, Vc\* is the maximum value among the switch node voltage references Va\*, Vb\*, Vc\*. In addition, when the second intermediate voltage Vz is adjusted by the second power converter 2 so that the second intermediate voltage Vz is equal to the second switch node voltage reference among the switch node voltage references Va\*, Vb\*, Vc\*, one of the switch nodes a\, b\, c\ having the second switch node voltage reference as its voltage reference can be permanently connected to the second intermediate node z, so that no switching operation is required to adjust the corresponding switch node voltage. For example, the second switch node voltage reference among the switch node voltage references Va\*, Vb\*, Vc\* is the minimum value among the switch node voltage references Va\*, Vb\*, Vc\*. In this way, two switch node voltages among the plurality of switch node voltages a\, b\, c\ are adjusted by the second power converter 2, so that no switching operation is required to adjust the two switch node voltages. Figure 1 In a power converter device, in which a first power converter 1 receives three different input voltages Va, Vb, Vc and includes three switch nodes a\, b\, c\, only a switch mode operation is required to adjust one of the three switch node voltages Va\, Vb\, Vc\. Therefore, compared with adjusting each of the three switch node voltages Va\, Vb\, Vc\ by a switch mode operation, the switching loss of the first power converter 1 is reduced.

[0048] The switch mode operation is used to adjust only one of the three switch node voltages Va\, Vb\, and Vc\. Figure 1 The operation mode of the first power converter 1 may be referred to as a 1 / 3 mode.

[0049] Figure 4 An example of a first power converter 1 and a second power converter 2 is shown in more detail. Figure 4 , the first power converter 1 includes a plurality of converter stages 10a, 10b, 10c, wherein each of the converter stages 10a, 10b, 10c is connected between a corresponding one of the input nodes a, b, c on one side and a first intermediate node x, a second intermediate node z, and a second ground node y on the other side. In addition, each of the converter stages 10a, 10b, 10c includes a reference Figure 1 A corresponding one of the switching nodes a\, b\, c\ described.

[0050] Reference Figure 4 , each of the converter stages 10a, 10b, 10c includes an inductor 11a, 11b, 11c connected between the input nodes a, b, c and the switching nodes a\, b\, c\. In addition, each of the converter stages 10a, 10b, 10c includes a switching circuit 12a, 12b, 12c connected between the switching nodes a\, b\, c\ on one side and the first and second intermediate nodes x and z and the second ground node y on the other side. More specifically, each switching circuit 12a, 12b, 12c includes: an input node 13a, 13b, 13c connected to the corresponding switching nodes a\, b\, c\ and the inductor 11a, 11b, 11c; a first output node 14a, 14b, 14c connected to the first intermediate node x; a second output node 15a, 15b, 15c connected to the second ground node y; and a third output node 16a, 16b, 16c connected to the second intermediate node z.

[0051] Each of the switching stages 12a, 12b, 12c is configured to receive control signals S12a, S12b, S12c from the control circuit 3 that govern the operation of the respective switching stage 12a, 12b, 12c. These control signals S12a, S12b, S12c are Figure 1 The portion of the control signal S1 which controls the operation of the first power converter 1 is shown in FIG.

[0052] Reference Figure 4 , the second power converter 2 includes two converter stages: a first converter stage 20p and a second converter stage 20r. The first converter stage 20p is connected between a first intermediate node x and a second ground node y on one side and a first output node p and a third ground node q on the other side. More specifically, the first converter stage 20p includes: a first input node 23p connected to the first intermediate node x, a second input node 24p connected to the second ground node y, a first output node 25p connected to the first output node p of the power converter device, and a fourth output node 26p connected to the third ground node q.

[0053] The second converter stage 20r is connected between the second ground node y and the second intermediate node z on one side and the third ground node q and the second output node r on the other side. More specifically, the second converter stage 20r includes: a first input node 23r connected to the second intermediate node z, a second input node 24r connected to the second ground node y, a first output node 25r connected to the second output node r of the power converter device, and a second output node 26r connected to the third ground node q.

[0054] Each of the first converter stage 20p and the second converter stage 20r may include an input capacitor 21p, 21r and an output capacitor 22p, 22r (in Figure 4 In the example shown, they are drawn outside the respective converter stages 20p, 20r). An input capacitor 21p is connected between input nodes 23p, 24p of the respective converter stage 20p, an input capacitor 21r is connected between input nodes 23r, 24r of the respective converter stage 20r, and an output capacitor 22p is connected between output nodes 25p, 26p of the respective converter stage 20p, an output capacitor 22r is connected between output nodes 25r, 26r of the respective converter stage 20r.

[0055] In accordance with Figure 4 In the power converter 2 of FIG. 1 , in the first operation mode of the power converter device, the first converter stage 20 p is configured to adjust the first intermediate voltage Vx, and the second converter stage 20 r is configured to adjust the second intermediate voltage Vz. Each of the converter stages 20 p, 20 r is configured to receive a corresponding control signal S2 p, S2 r from the control circuit 3. These control signals S2 p, S2 r are Figure 1 A portion of a control signal S2 which controls the operation of the second power converter 2 is shown.

[0056] Reference Figure 4 , between the output nodes 25p, 26p of the first converter stage 20p, a first portion Vp of the output voltage Vout is available, and between the output nodes 25r, 26r of the second converter stage 20r, a second portion Vr of the output voltage Vout is available. For the purpose of illustration, it is assumed that both output voltage portions are referenced to the third ground node q. For example, the output voltage Vout is given by the first output voltage portion Vp minus the second output voltage portion Vr. According to an example, the first output voltage portion is positive and the second output voltage portion is negative, so the output voltage Vout between the first output node p and the second output node r is positive.

[0057] According to an example, Figure 4 As shown by the middle dotted line, the second ground node y is connected to the third ground node q.

[0058] In accordance with Figure 4In the first power converter 1, controlling the input currents Ia, Ib, Ic of the respective converter stages 10a, 10b, 10c to control the input power Pin includes controlling the voltages VLa, VLb, VLc across the inductors 11a, 11b, 11c. The voltages VLa, VLb, VLc across the inductors 11a, 11b, 11c in each of the converter stages 10a, 10b, 10c are given by the corresponding input voltages Va, Vb, Vc minus the corresponding switch node voltages Va\, Vb\, Vc\, VLa=Va-Va\ (2a)

[0059] VLb=Vb-Vb\ (2b)

[0060] VLc=Vc-Vc\ (2c), Thus, the inductor voltages VLa, VLb, VLc can be adjusted by adjusting the switch node voltages Va\, Vb\, Vc\, and thus the input currents Ia, Ib, Ic and the input power Pin can be adjusted.

[0061] Figure 5 An example for implementing the switching circuits 12a, 12b, 12c is shown in more detail. More specifically, Figure 5 One of the converter stages 10a, 10b, 10c is shown with a detailed example of a corresponding switching circuit. Figure 5 The converter stage 10i shown represents Figure 4 Any of the converter stages 10a, 10b, 10c shown. Figure 5 , i represents a corresponding input node, Vi represents a corresponding input voltage; Ii represents a corresponding input current, i\ represents a corresponding switch node; Vi\ represents a corresponding switch node voltage; 11i represents a corresponding inductor connected between the input terminal i and the switch node i\; VLi represents a voltage across the inductor 11i, 12i represents a corresponding switch circuit; 13i represents an input terminal of the switch circuit 12i; and 14i, 15i, 16i represent output nodes of the switch circuit 12i. Each of the converter stages 10a, 10b, 10c may be configured according to Figure 5 This is achieved by the converter stage 10i shown.

[0062] Reference Figure 5 , the switch circuit 12i includes an electronic switch 17i connected between the switch node i\ and the second output node 15i, the second output node 15i is connected to the second ground node y. The first rectifier element 18i is connected between the switch node i\ and the first output node 14i, the first output node 14i is connected to the first intermediate node x. The second rectifier element 19i is connected between the switch node i\ and the second intermediate node z.

[0063] exist Figure 5 In the converter stage 10i shown, adjusting the switch node voltage Vi\ includes operating the electronic switch 17i in the switch mode. According to one example, operating the electronic switch 17i in the switch mode includes: operating the electronic switch 17i in a plurality of consecutive drive cycles, each drive cycle having a drive cycle duration Ts described above; and operating the electronic switch 17i in the on state (switch on state) during the on time Ton, and operating the electronic switch 17i in the off state (switch off state) during the off time Toff. The duration of the on time Ton and the off time Toff can be changed in order to adjust the switch node voltage Vi\. According to one example, the electronic switch 17i is operated at a fixed switching frequency, so that each drive cycle has the same duration.

[0064] During the on-time Ton, the potential at the switch node i\ is at least approximately equal to the potential at the second ground node y. Referring to the above, the potential at the second ground node y is adjusted to be at least approximately equal to the potential at the first ground node n, so that during the on-time Ton, the voltage VLi across the inductor 11i is at least approximately equal to the input voltage Vi. This increases the amplitude of the input current Ii. The current direction of the input current Ii depends on the polarity of the input voltage Vi. When the input voltage Vi is positive, the input current Ii is positive and Figure 5 When the input voltage Vi is negative, the input current Ii is negative and flows in the direction shown in FIG. Figure 5 Flow in the direction opposite to that shown.

[0065] During the off state of the electronic switch 17i, the switch node voltage Vi\ is clamped to the first intermediate voltage Vx by the first rectifier element 18i, or is clamped to the second intermediate voltage Vz by the second rectifier element 19i. Figure 5 In the example shown, the first rectifier element 18i and the second rectifier element 19i are passive rectifier elements, such as diodes. The polarity of the first rectifier element 18i is such that the first rectifier element 18i takes over the positive input current Ii during the off-state of the switch element 17i, so that the first rectifier element 18i clamps the switch node voltage Vi\ to the first intermediate voltage Vx. The polarity of the second rectifier element 19i is such that the second rectifier element 19i takes over the negative input current Ii during the off-state of the switch element 17i, so that the second rectifier element 19i clamps the switch node voltage Vi\ to the second intermediate voltage Vz. During the off-state, the amplitude of the input current Ii is reduced.

[0066] Referring to the above, the input current Ii increases during the on-time Ton and decreases during the off-time. As used herein, “adjusting the input current” (such as Figure 5 The input current Ii) shown in includes adjusting the average value of the input current within the duration of one or more drive cycles. The average input current depends on the average switch node voltage Vi\, wherein "adjusting the switch node voltage" as used herein includes adjusting the average switch node voltage within the duration of one or more drive cycles. The (average) switch node voltage within the duration of one drive cycle is given by the following formula:

[0067] When the input voltage Vi is positive and therefore the input current Ii is positive,

[0068]

[0069] And when the input voltage Vi is negative and therefore the input current Ii is negative,

[0070]

[0071] In the following, di, where

[0072]

[0073] represents the duty cycle of the switch mode operation of the electronic switch 17i and simultaneously represents the duty cycle of the switch mode operation of the converter stage 10i. Based on this and considering equations (3a) and (3b), the (average) switch node voltage is given by:

[0074] When the input voltage Vi is positive,

[0075] Vi\=di·Vx (5a),

[0076] And when the input voltage Vi is negative,

[0077] V\=di·Vz (5b).

[0078] Therefore, in order to adjust the input power received by converter stage 10i, the (average) switch node voltage Vi of converter stage 10i, and thus the (average) input current Ii of converter stage 10i, may be adjusted by appropriately adjusting the duty cycle of the switch mode operation of converter stage 10i.

[0079] It should be noted that, except for a short duration when the input voltage Va, Vb, Vc is close to zero crossing, the amplitude of the average inductor voltage VLa, VLb, VLc is low compared to the amplitude of the input voltage Va, Vb, Vc. Therefore, the switch node voltage Va\, Vb\, Vc\ substantially follows the input voltage Va, Vb, Vc. The "average inductor voltage" is the average value of the voltage VLa, VLb, VLc across one inductor 11a, 11b, 11c during at least one drive cycle of the switch mode operation of the electronic switch 17i.

[0080] exist Figure 5 In the example shown, the rectifier elements (clamping elements) 18i, 19i are passive rectifier elements. However, this is only an example. Figure 6 In another example shown, the rectifier elements 18i, 19i are active rectifier elements, each of which includes an electronic switch 181i, 191i and a passive rectifier element 182i, 192i, such as a diode, connected in parallel with the electronic switch. Figure 6 Each of the active rectifier elements 18i, 19i shown can be operated so that the electronic switch 181i, 191i is turned on each time the parallel passive rectifier element is forward biased, so that the electronic switch bypasses the passive rectifier elements 182i, 192i to reduce conduction losses. The operation of the switches 181i, 191i of the active rectifier elements 18i, 19i can be controlled by the control circuit 3 in such a way that in each drive cycle, one of the electronic switches 181i, 191i is operated in a complementary manner to the electronic switch 17i. That is, one of the electronic switches 181i, 191i is in the on state when the electronic switch 17i is in the off state, and is in the off state when the electronic switch 17i is in the on state. Which of the electronic switches 181i, 191i operates in the switching mode depends on the polarity of the input voltage Vi. When the input voltage Vi is positive and thus the input current Ii is positive, the electronic switch 181i in the first rectifier element 18i operates in switching mode.When the input voltage Vi is negative and thus the input current Ii is negative, the electronic switch 191i operates in switching mode.

[0081] According to one example, the electronic switch 17i of the switch circuit 12i is a bidirectional blocking electronic switch. A "bidirectional blocking switch" is an electronic switch that is configured to block regardless of the polarity of the voltage applied across the switch in the off state. The bidirectional blocking electronic switch can be implemented in various ways. Fig. 7A and Figure 7B Two different examples for implementing a bidirectional blocking switch are shown in FIG.

[0082] exist Fig. 7AIn the example shown, the bidirectional blocking switch 17i includes two unidirectional blocking electronic switches 171i, 172i connected in series. A "unidirectional blocking switch" is an electronic switch that, in the off state, blocks when the voltage applied across the switch has a first polarity, and conducts when the voltage applied across the switch has a second polarity opposite to the first polarity.

[0083] Each of the one-way blocking switches 171i, 172i includes a switching element and a rectifier element connected in parallel with the switching element, such as a diode. The one-way blocking switches are connected in series so that the freewheeling elements are connected in reverse series. For example, each of the one-way blocking switches 171i, 172i can be implemented as a MOSFET. In a MOSFET, an integrated body diode forms a rectifier element. However, implementing each of the one-way blocking switches as a MOSFET is only an example. Any other type of electronic switch and a rectifier element (such as a diode) connected in parallel with the electronic switch can also be used to implement these switches.

[0084] exist Figure 7B In the example shown, the bidirectional blocking switch is implemented as a bidirectional blocking GaN switch, which is a monolithic implementation of a bidirectional switch.

[0085] Fig. 7A and Figure 7B Each of the bidirectional blocking switches 17i shown in the figure includes two control nodes, wherein each of these control nodes is connected to the control node of one of the switches 171i, 172i, and is configured to receive a control signal for turning on or off the corresponding switch 171i, 172i. According to one example, the two control nodes receive the same control signal S17i, so that the two switches 171i, 172i are turned on and off at the same time.

[0086] As reference Figure 4 As illustrated, each of the converter stages 10a, 10b, 10c comprises an inductor 11a, 11b, 11c. Furthermore, the power converter arrangement may comprise an input filter 4 configured to filter current ripple of the input current Ia, Ib, Ic which may be generated by the switch mode operation of the first power converter 1. Although Figure 4 One inductor 11a, 11b, 11c in each of the converter stages 10a, 10b, 10c and an input filter 4 connected between the input nodes a, b, c and the converter stages 10a, 10b, 10c are shown, but this is only an example. Figure 4The inductors 11a, 11b, 11c shown in FIG. 4 may each include several inductor sections, and the input filter 4 may include several filter stages, wherein the inductor sections and the filter stages are alternately arranged between the input nodes a, b, c and the switching nodes a\, b\, c\. Figure 8 An example of such an arrangement is shown in .

[0087] exist Figure 8 In the example shown in , each of the inductors 11a, 11b, 11c includes three inductor sections 111a to 113a, 111b to 113b, 111c to 113c, and the input filter includes three filter stages, wherein each filter stage includes three inductors 411a to 411c, 412a to 412c, 413a to 413c. Between each input node a, b, c and the corresponding switching node a\, b\, c\, the three inductor sections 111a to 113a, 111b to 113b, 111c to 113c of the power stage inductors 11a, 11b, 11c and the inductors of the filter stages are alternately arranged. Furthermore, the first and second filter stages each comprise a plurality of capacitors 421a to 421c, 422a to 422c, wherein each of these capacitors couples one of the three inductors 411a to 411c, 412a to 412c to the first ground node n via a respective further capacitor 431, 432.

[0088] Fig. 9 An example of a first converter stage 2p and a second converter stage 2r for implementing the second power converter 2 is shown. Fig. 9 In the example shown in , each of the first converter stage 2p and the second converter stage 2r is implemented as a buck converter including an electronic switch 27p, 27r, an inductor 29p, 29r and a rectifier element (freewheeling element) 28p, 28r. The rectifier element 28p, 28r can be implemented as a passive rectifier element, such as a diode (as shown), or as an active rectifier element (synchronous rectifier).

[0089] In the first converter stage 2p, an electronic switch 27p and an inductor 29p are connected in series between a first input node 23p and a first output node 25p, and a rectifier element 28p is connected in parallel with a series circuit including the inductor 29p and the output capacitor 22p. In addition, a second input node 24p is connected to a second output node 26p. In the second converter stage 2r, an electronic switch 27r and an inductor 29r are connected in series between a first input node 23r and a first output node 25r, and a freewheeling element 28r is connected in parallel with a series circuit including the inductor 29r and the output capacitor 22r. In addition, a second input node 24r is connected to a second output node 26r.

[0090] The electronic switches 27p, 27r in each of the converter stages 2p, 2r may be operated in a switching mode such that each of the switches 27p, 27r is alternately turned on and off. The converter stages 2p, 2r may be operated at a fixed switching frequency such that each drive cycle of operating the electronic switches 27p, 27r has the same duration. The switching frequency of operating the first converter stage 2p and the second converter stage 2r of the second power converter may be in the same range as the switching frequency of the converter stages 10a, 10b, 10c of the first power converter 1.

[0091] In the first converter stage 2p, when the electronic switch 27p is in the on state, the output current Iout flows through the electronic switch 27p and the inductor 29p. When the electronic switch 27p is turned off, the freewheeling element 28p takes over the output current Iout from the electronic switch 27p.

[0092] Reference Fig. 9 The electronic switches 27p, 27r in the first converter stage 2p and the second converter stage 2r are controlled by control signals S27p, S27r. According to one example, these control signals (drive signals) correspond to the respective control signals S2p, S2r received by the first converter stage 2p and the second converter stage 2r.

[0093] In the second converter stage 2r, when the electronic switch 27r is in the on state, the output current Iout flows through the electronic switch 27r and the inductor 29r. When the electronic switch 27r is turned off, the freewheeling element 28r takes over the current from the electronic switch 27r.

[0094] With reference to the above, in the first operating mode of the power converter device, the first converter stage 2p adjusts the voltage level of the first intermediate voltage Vx. For example, when the duty cycle of operating the first converter stage 2p makes the (average) first intermediate current Ix higher than the (average) switching current I27p, the amplitude of the first intermediate voltage Vx increases. In this case, the input capacitor 21p is charged so that the first intermediate voltage Vx increases. The "average first intermediate current" is the average value of the first intermediate current Ix within one or more drive cycles of the switch mode operation of the electronic switch 27p. The average switch current I27p is the average value of the current passing through the switch 27p within one or more drive cycles of the switch mode operation of the electronic switch 27p. The first intermediate current Ix is the current received at the first intermediate node x. Equivalently, when the (average) first intermediate current Ix is lower than the average switch current I27p, the first intermediate voltage Vx decreases.

[0095] For example, when the duty cycle of the switch mode operation of the electronic switch 27r in the second converter stage 2r makes the amplitude of the average second intermediate current Iz higher than the amplitude of the average switching current I27r, the amplitude of the second intermediate voltage Vz increases. The "average second intermediate current Iz" is the average value of the second intermediate current Iz within one or more drive cycles of the switch mode operation of the electronic switch 27r, and the average switching current I27r is the average value of the current passing through the switch 27r within one or more drive cycles of the switch mode operation of the electronic switch 27r. The second intermediate current Iz is the (negative) current received at the second intermediate node z. Equivalently, when the amplitude of the average second intermediate current Iz is lower than the average switching current I27r, the amplitude of the second intermediate voltage Vz decreases. In the following, unless otherwise specified, the second intermediate current Iz is the average value of the second intermediate current Iz, and the average switching current I27p is the average value of the switching current I27p.

[0096] Fig.10 1 shows a block diagram of a control circuit 3 according to an example. It should be noted that Fig.10 The functions of the control circuit 3 are shown instead of the specific implementation. The control circuit 3 can be implemented in various ways. According to one example, the control circuit 3, which can include several control units 31 to 39r, can be implemented as a dedicated control circuit. According to another example, the control circuit 3 includes a microcontroller, wherein different control units can be implemented as different program codes, each program code being configured to operate the microcontroller so that it has the function of a corresponding control unit.

[0097] Reference Fig.10 , one of the control units of the control circuit 3 is an output signal controller 31. The output signal controller 31 is configured to receive the measured output signal Sout' and provide input current references Ia*, Ib*, Ic*. Each of the input current references Ia*, Ib*, Ic* represents a desired current level of an average value of a corresponding input current in the input currents Ia, Ib, Ic. As previously described, the average value of the input currents Ia, Ib, Ic is an average value of the currents in one or more drive cycles of the switch mode operation of the converter stages 10a, 10b, 10c receiving the corresponding input currents Ia, Ib, Ic.

[0098] Reference Fig.10 Another control unit of the control circuit 3 is a ground signal controller 33. The ground signal controller receives the measured ground signal Syn' and outputs a ground control signal Scm*.

[0099] Reference Fig.10The input current controller 32 receives input current references Ia*, Ib*, Ic* and a ground control signal Scm*, and is configured to output switch node voltage references Va\*, Vb\*, Vc\* to control the input currents Ia, Ib, Ic according to the input current references Ia*, Ib*, Ic* and the ground control signal Scm*.

[0100] The duty cycle controller 34 receives the switch node voltage references Va\*, Vb\*, Vc\* from the input current controller 32, the first intermediate voltage reference Vx* from the first intermediate voltage reference controller 37x, and the second intermediate voltage reference Vz* from the second intermediate voltage reference controller 37z. The duty cycle controller 34 is configured to calculate the duty cycles da, db, dc for operating the converter stages 10a, 10b, 10c of the first power converter 1 based on the switch node voltage references Va\*, Vb\*, Vc\* and the first intermediate voltage references Vx* and the second intermediate voltage references Vz*.

[0101] Basically, calculating each of the duty cycles da, db, dc may include dividing the corresponding switch node voltage reference Va\*, Vb\*, Vc\* by one of the first intermediate voltage reference Vx* and the second intermediate voltage reference Vz*. In particular, calculating each of the duty cycles da, db, dc may include dividing the corresponding switch node voltage reference Va\*, Vb\*, Vc\* by the first intermediate voltage reference Vx* when the corresponding switch node voltage reference is positive Va\*, Vb\*, Vc\*, and dividing the corresponding switch node voltage reference Va\*, Vb\*, Vc\* by the second intermediate voltage reference Vz* when the corresponding switch node voltage reference is negative Va\*, Vb\*, Vc\*. This is explained below with reference to calculating the duty cycle da of the first converter stage 10a based on the switch node voltage reference Va\* associated with the first converter stage 10a and the first intermediate voltage reference Vx* and the second intermediate voltage reference Vz*. The duty cycles db, dc of the converter stages 10 b, 10 c are obtained in an equivalent manner by the duty cycle controller 34 .

[0102] It should be noted that the "duty cycle" da, db, dc as used herein for brevity represents the duty cycle information, which is the duty cycle information of an electronic switch (such as a Figure 5 and Figure 6 The switch 17i in the drive cycle provides the information required for the switch to operate at a given duty cycle within one drive cycle.

[0103] When the switch node voltage reference Va\* is positive, the duty cycle controller 34 is configured to calculate the duty cycle da based on the following formula:

[0104]

[0105] In this example, in the switch circuit 12a (see Figure 4 ) in the electronic switch ( Figure 5 and Figure 6 During the off state of the first rectifier element ( Figure 5 and Figure 6 18i) in the figure clamps the switch node to the first intermediate node x. In addition, when the switch node voltage reference Va\* is negative, the duty cycle controller 34 is configured to calculate the duty cycle da based on the following formula:

[0106]

[0107] In this example, in the switch circuit 12a (see Figure 4 ) in the electronic switch ( Figure 5 and Figure 6 During the off state of the first rectifier element ( Figure 5 and Figure 6 18i) in the switch node is clamped to the second intermediate node z. In the example described earlier in this article, the second intermediate voltage Vz is negative. Therefore, the intermediate voltage reference Vz* is also negative, so that the duty cycle da calculated based on equation (6b) produces a positive duty cycle value.

[0108] Equivalently, when the corresponding switch node voltage references Vb\*, Vc\* are positive, the duty cycles db, dc are calculated based on:

[0109]

[0110] And when the corresponding switch node voltage reference Vb\*, Vc\* is negative, the duty cycle db, dc is calculated based on:

[0111]

[0112] Reference Fig.10 The drive circuit 35 receives the duty cycles da, db, dc from the duty cycle controller 34 and is configured to generate control signals S12a, S12b, S12c received by the converter stages 10a, 10b, 10c based on the duty cycles da, db, dc. In particular, the drive circuit 35 is configured to drive the electronic switches in the switch circuit 12a of the converter stage 10a according to the duty cycle da, drive the electronic switches in the switch circuit 12b of the converter stage 10b according to the duty cycle db, and drive the electronic switches in the switch circuit 12c of the converter stage 10c according to the duty cycle dc.

[0113] The output signal controller 31 , the input current controller 32 , the ground signal controller 33 and the duty cycle controller 34 form an input power controller for controlling the input power received by the first power converter 1 .

[0114] Reference Fig.10 , the control circuit 3 also includes a classifier 36, which is configured to receive the switch node voltage references Va\*, Vb\*, Vc\* from the input current controller 32, and is configured to output a maximum switch node voltage reference Vmax* and a minimum switch node voltage reference Vmin*. The maximum switch node voltage reference Vmax* is the highest one among the switch node voltage references Va\*, Vb\*, and Vc\*. That is, the maximum switch node voltage reference Vmax* is the most positive one among the switch node voltage references Va\*, Vb\*, and Vc\*. The minimum switch node voltage reference Vmin* is the lowest one among the switch node voltage references Va\*, Vb\*, and Vc\*. That is, the minimum switch node voltage reference Vmin* is the most negative one among the switch node voltage references Va\*, Vb\*, and Vc\*.

[0115] Referring to the above, each of the switch node voltage references Va\*, Vb\*, Vc\* follows the corresponding input voltage Va, Vb, Vc. Figure 2 In an input voltage system of three AC input voltages of the type shown in , at each time, at least one of the three input voltages Va, Vb, Vc is positive, and at least one of the three input voltages Va, Vb, Vc is negative. Therefore, except for negligible time instances where the two voltages cross, there is a maximum (most positive) input voltage and a minimum (most negative) input voltage at each time. Therefore, at each time, there is a maximum (most positive) switch node voltage reference Vmax* and a minimum (most negative) switch node voltage reference Vmin*.

[0116] Reference Fig.10 , the first intermediate voltage reference controller 37x receives the maximum switch node voltage reference Vmax* and provides the first intermediate voltage reference Vx*, and the second intermediate voltage reference controller 37z receives the minimum switch node voltage reference Vmin* and provides the second intermediate voltage reference Vz*. In the first operation mode of the power converter device, the first intermediate voltage reference controller 37x outputs the maximum switch node voltage reference Vmax* as the first intermediate voltage reference Vx*, and the second intermediate voltage reference controller 37z outputs the minimum switch node voltage reference Vmin* as the second intermediate voltage reference Vz*.

[0117] Therefore, the duty ratios da, db, dc obtained based on equations (6a) to (7c) in the first operating mode have the effect that two of the three duty ratios are equal to 1, so that the electronic switch ( Figure 5 and Figure 6 17i in the figure is turned off during the entire corresponding driving cycle. Therefore, in a switching circuit including an active rectifier element (such as Figure 6 In a converter stage of a switching circuit 12i) of the type shown in FIG. 1 , the electronic switch comprised in one of the two active rectifier elements is turned on throughout the respective drive cycle.

[0118] It should be noted that the duration for which one of the switch node voltage references Va\*, Vb\*, Vc\* is the maximum switch node voltage reference Vmax* is much longer than the duration of one drive cycle of the corresponding converter stage 10a, 10b, 10c. Therefore, in the corresponding converter stage 10a, 10b, 10c, the electronic switches are in the off state and the electronic switches of the corresponding active rectifier elements are in the on state for a duration much longer than the duration of one drive cycle. Therefore, the corresponding converter stage 10a, 10b, 10c operates statically for a duration much longer than the duration of one drive cycle, which saves switching losses.

[0119] Equivalently, the duration for which one of the switch node voltage references Va\*, Vb\*, Vc\* is the minimum switch node voltage reference Vmin* is much longer than the duration of one drive cycle of the corresponding converter stage 10a, 10b, 10c. Therefore, in the corresponding converter stage 10a, 10b, 10c, the electronic switch is in the off state and the electronic switch of the corresponding active rectifier element is in the on state for a duration much longer than the duration of one drive cycle. Therefore, the corresponding converter stage 10a, 10b, 10c operates statically for a duration much longer than the duration of one drive cycle, which saves switching losses.

[0120] Therefore, in the first operation mode of the power converter device, at each time, there are two statically operated converter stages 10a, 10b, 10c, while only one of the converter stages operates in switching mode. Such operation is possible because the second power converter adjusts the first switching node voltage Vx and the second switching node voltage Vz according to the maximum switching node voltage reference Vmax* and the minimum switching node voltage reference Vmin*.

[0121] In order to control the first switch node voltage Vx, according to Fig.10The control circuit 3 comprises a first intermediate voltage controller 38p, which receives the first intermediate voltage reference Vx* and generates a first duty cycle dp for operating the first converter stage 2p. The first drive circuit 39p receives the first duty cycle dp and generates a control signal S2p for operating the first converter stage 2p based on the duty cycle dp. In particular, the control signal S2p controls the operation of the electronic switch 27p in the first converter stage 2p.

[0122] In order to control the second switch node voltage Vz, according to Fig.10 The control circuit 3 includes a second intermediate voltage controller 38r, which receives the second intermediate voltage reference Vz* and generates a first duty cycle dr for operating the second converter stage 2p. The second drive circuit 39p receives the second duty cycle dr and generates a control signal S2r for operating the second converter stage 2r based on the duty cycle dr. In particular, the control signal S2r controls the operation of the electronic switch 27r in the second converter stage 2r.

[0123] The following is shown and explained according to Fig.10 Detailed examples of some of the control units 31 to 39r included in the control circuit 3.

[0124] Fig.11 An example of an output signal controller 31 that receives the measured output signal Sout' and provides the input current references Ia*, Ib*, Ic* is shown. Fig.11 , the output signal controller 31 generates a conductance reference G* representing the desired input conductance of the first power converter 1. Each of the input current references Ia*, Ib*, Ic* is generated by multiplying the conductor current reference G* by the corresponding measured input voltage Va', Vb', Vc' using corresponding multipliers 314a, 314b, 314c. In this way, each of the input current references Ia*, Ib*, Ic* is proportional to the corresponding input voltage Va, Vb, Vc, thereby realizing the PFC function. Each of the measured input voltages Va', Vb', Vc' represents the corresponding input voltage Va, Vb, Vc, and can be obtained by measuring the input voltages Va, Vb, Vc using a conventional voltage measurement circuit (not shown).

[0125] Reference Fig.11, calculating the conductance reference G* includes subtracting the measured output signal Sout' from the output signal reference Sout* by a subtractor 311. The output signal reference Sout* represents the desired signal level of the output signal to be adjusted (e.g., the output voltage Vout or the output current Iout). The output signal of the subtractor is an error signal representing the difference between the signal level of the desired output signal and the signal level of the existing (measured) output signal Sout'. A controller such as, for example, a PI (proportional integral) controller receives the error signal and outputs a signal Pin* representing the desired (average) input power. The average input power is the input power within at least one drive cycle of the switch mode operation of the first power converter 1. In the example described earlier in this article, where the input voltage is a sinusoidal input voltage, and due to the PFC function of the first power converter 1, the input currents Ia, Ib, and Ic are sinusoidal input currents, the input power at each of the three input terminals a, b, and c has a sinusoidal square waveform. Due to the phase shift (120°) between the input voltages Va, Vb, Vc and the corresponding phase shift between the input currents Ia, Ib, Ic, the total input power Pin is substantially constant. Therefore, the input power reference Pin* is substantially constant.

[0126] Reference Fig.11 To obtain the conductivity reference G*, the divider 313 divides the input power reference Pin* by Where V represents the amplitude of the input voltage Va, Vb, Vc. The amplitude is given by times the above RMS value is given.

[0127] Fig.12 An example of the input current controller 32 and the ground signal controller 33 is shown. Fig.12 The current controller 32 includes three controller branches, wherein each of these controller branches is configured to provide one of three switch node voltage references Va\*, Vb\*, Vc\*. In the following, a first controller branch configured to generate a switch node voltage Va\* based on an input current reference Ia* and a ground control signal Scm* will be briefly described. The other two controller branches are implemented and operated in the same manner. In the three controller branches, corresponding components are marked with corresponding reference numerals. "Corresponding reference numerals" are reference numerals having the same number and differing by adding the character "a" in the first controller branch, the character "b" in the second controller branch, and the character "c" in the third controller branch.

[0128] Reference Fig.12, the first controller branch includes a subtractor 321a, which subtracts the measured input current Ia' from the input current reference Ia* to obtain an input current error. The measured input current Ia' represents the (average) input current Ia and can be obtained by measuring the input current Ia using a conventional current measurement circuit (not shown) and low-pass filtering the measured value to obtain the average value of the input current Ia within at least one drive cycle. A controller 322a (such as a PI controller) generates an inductor voltage reference VLa* based on the input current error. The inductor voltage reference VLa* represents the desired average voltage across the inductor 11a in the first converter stage 10a. The inductor voltage reference VLa* represents the inductor voltage required to achieve the first input current Ia at least approximately equal to the first input current reference Ia*. The switch node voltage reference Va\* is given by the measured first input voltage Va' minus the inductor voltage reference VLa* and minus the ground signal Scm*, and is provided by the subtractor 324.

[0129] from Fig.12 It can be seen that the ground signal Scm* affects each of the input voltage references Va\*, Vb\*, and Vc\* in the same way. That is, when the ground signal Scm* changes, each of the input voltage references Va\*, Vb\*, and Vc\* changes in the same way. Therefore, the ground signal Scm* can also be called a common mode signal.

[0130] Reference Fig.12 , the ground signal Scm can be obtained by subtracting the measured ground signal Syn' from the ground signal reference Syn* by the subtractor 331. According to an example, the ground signal reference Syn* is zero, Syn*=0, so the voltage or current between the first ground node n and the second ground node y is zero. The output signal of the subtractor 331 represents the difference between the ground signal reference Syn* and the measured ground signal Syn'. The output signal is received by a controller 332 such as a PI controller, and the controller 332 outputs the ground signal Scm based on the output signal of the subtractor 331.

[0131] Fig.13 An example of a first intermediate voltage reference controller 37x and a second intermediate voltage reference controller 37z is shown. In this example, each of the first intermediate voltage reference controller 37x and the second intermediate voltage reference controller 37z includes a maximum selector 371x, 371z, which is configured to receive two signals, detect which of the two signals has a higher amplitude, and output the signal with the higher amplitude.

[0132] Reference Fig.13, the maximum selector 371x included in the first intermediate voltage reference controller 37x receives the maximum switch node voltage reference Vmax* and the measured first output voltage portion Vp'. According to one example, both the maximum switch node voltage reference Vmax* and the measured first output voltage portion Vp' are positive, so the maximum selector 371x outputs the more positive one of the two signals (values).

[0133] Reference Fig.13 , the maximum selector 372z included in the second intermediate voltage reference controller 37z receives the minimum switch node voltage reference Vmin* and the measured second output voltage portion Vr'. According to one example, both the minimum switch node voltage reference Vmin* and the measured second output voltage portion Vr' are negative, so the maximum selector 371z outputs the more negative one of the two signals (values).

[0134] Referring to the above, in the first operation mode of the power converter device, the first intermediate voltage reference Vx* is equal to the maximum switch node voltage reference Vmax*, and the second intermediate voltage reference Vz* is equal to the minimum switch node voltage reference Vmin*. Therefore, considering the functions of the first intermediate voltage reference controller 37x and the second intermediate voltage reference controller 37z, when the maximum switch node voltage reference Vmax* is higher (more positive) than the measured first output voltage portion Vp' and when the minimum switch node voltage reference Vmin* is lower (more negative) than the measured second output voltage portion Vr', the power converter device operates in the first operation mode.

[0135] Fig.14 An example of a first intermediate voltage controller 38p and a second intermediate voltage controller 38r is shown. As described above, the first intermediate voltage controller 38p receives the first intermediate voltage reference Vx* and generates a duty cycle dp for operating the electronic switch 27p in the first converter stage 2p of the second power converter 2. The second intermediate voltage controller 38r receives the second intermediate voltage reference Vz* and generates a duty cycle dr for operating the electronic switch 27r in the second converter stage 2r of the second power converter 2. The first intermediate voltage controller 38p and the second intermediate voltage controller 38r are implemented in the same manner, wherein corresponding components have corresponding reference numerals. "Corresponding reference numerals" are reference numerals having the same number and having an added "p" in the case of the first intermediate voltage controller 38p and an added "r" in the case of the second intermediate voltage controller 38r. In the following, the first intermediate voltage controller 38p and its functions are described in detail. The description applies accordingly to the second intermediate voltage controller 38r.

[0136] Reference Fig.14, the first intermediate voltage controller 38p includes a subtractor 381p that subtracts the first intermediate voltage reference Vx* from the measured first intermediate voltage Vx'. The measured first intermediate voltage Vx' represents the first intermediate voltage Vx and can be obtained by measuring the first intermediate voltage Vx using a normal mode voltage measurement circuit (not shown). The output signal of the subtractor 381p representing the difference between the first intermediate voltage reference Vx* and the measured first intermediate voltage Vx' is received by a controller 382p, which is, for example, a PI controller. Another subtractor 383p subtracts the output signal of the controller 382p from the first (average) intermediate current Ix'. The first (average) intermediate current Ix' can be measured using a current sensor, can be calculated based on the measured input currents Ia', Ib', Ic', or can be calculated based on the duty cycles da, db, dc of the three converter stages 10a, 10b, 10c. The first (average) intermediate current is Fig.14 The average value of the intermediate current Ix is an average value within one or more driving cycles of the switching mode operation of the first power converter 1 .

[0137] Reference Fig.14 The divider 384p divides the output signal of the subtractor 383p by the measured first inductor current I29p', where the measured first inductor current I29p' represents the current passing through the inductor 29p'.

[0138] Fig.14 The first intermediate voltage controller 38p shown in is configured to control the operation of the first converter stage 2p taking into account the first intermediate voltage reference Vx*, the measured first intermediate voltage Vx' and the measured first intermediate current Ix' so that the first intermediate voltage Vx is at least approximately equal to the first intermediate voltage reference Vx* so that the first intermediate voltage Vx tracks the first intermediate voltage reference Vx*. Equivalently, Fig.14 The second intermediate voltage controller 38r shown in is configured to control the operation of the second converter stage 2r taking into account the second intermediate voltage reference Vz*, the measured second intermediate voltage Vz' and the measured second intermediate current Iz', so that the second intermediate voltage Vz is at least approximately equal to the second intermediate voltage reference Vz*, so that the second intermediate voltage Vz tracks the second intermediate voltage reference Vz*.

[0139] Instead of a subtractor such as the subtractor 383p in the first intermediate voltage controller, the second intermediate voltage controller 38r comprises an adder 383r which adds the output signal of the controller 382r to the second (average) intermediate current Iz'. A divider 384r divides the output signal of the adder 383r by the measured second inductor current I29r'.

[0140] Reference Fig.10 , in the case where the measured first output voltage portion Vp' is higher than the maximum switch node voltage reference Vmax*, the first intermediate voltage reference Vx* is equal to the measured first output voltage portion Vp'. In this case, the first intermediate voltage controller 38p controls the first intermediate voltage Vx to be substantially equal to the first output voltage portion Vp', which includes the duty cycle dp generated by the first intermediate voltage controller 38r being equal to 1, i.e. dp=1, so that the switch 27p is permanently turned on.

[0141] Equivalently, in the case where the magnitude of the measured second output voltage Vr' is higher than the magnitude of the minimum switch node voltage reference, the second intermediate voltage Vz* is equal to the measured second output voltage portion Vr'. In this case, the second intermediate voltage controller 38r controls the second intermediate voltage Vz to be substantially equal to the second output voltage portion Vr, which includes the duty cycle dr generated by the second intermediate voltage controller 38r being equal to 1, i.e. dr=1, so that the switch 27r is permanently turned on.

[0142] Fig.15 A signal diagram illustrating operation of a power converter device in a first operating mode is shown. More specifically, Fig.15 The signal diagrams of the following items during one cycle of the input voltages Va, Vb, Vc are shown: the input voltages Va, Vb, Vc; the input currents Ia, Ib, Ic; the output voltage Vout; the first intermediate voltage Vx and the first output voltage portion Vp; the magnitudes of the second intermediate voltage Vz and the second output voltage portion Vr (in the example described above, both voltages Vz, Vr are negative); the total DC link voltage Vxz, which is the voltage between the first intermediate node x and the second intermediate node z; and the ground current Iyn. Fig.15 It can be seen from FIG. 1 that each of the input currents Ia, Ib, Ic has the same waveform as the corresponding input voltage Va, Vb, Vc, so that the power converter device has a PFC function. Fig.15 The instantaneous input currents Ia, Ib, Ic are shown, which include high frequency variations due to the switch-mode operation of the first power converter 1 .

[0143] Referring to the above, in the first operating mode of the power converter device, the first converter stage 2p in the second power converter 2 adjusts the first intermediate voltage Vx so that the first intermediate voltage Vx is at least approximately equal to the maximum switching node voltage reference Vmax*. In addition, as explained above, each of the switching node voltage references Va\*, Vb\*, Vc\* is similar to the corresponding input voltage Va, Vb, Vc. Therefore, in the time period when the first input voltage Va is the maximum input voltage (that is, the most positive one of the input voltages Va, Vb, Vc), the first intermediate voltage Vx substantially follows the first input voltage Va. Equivalently, in the time period when the second input voltage Vb is the maximum input voltage, the first intermediate voltage Vx substantially follows the second input voltage Vb; and in the time period when the third input voltage Vc is the maximum input voltage, the first intermediate voltage Vx substantially follows the third input voltage Vc. From Fig.15 It can be seen from FIG. 1 that within one third of one cycle of the input voltages Va, Vb, Vc, each of the input voltages Va, Vb, Vc is the maximum input voltage, so that the first intermediate voltage Vx has a three-pulse waveform.

[0144] Equivalently, in the time period when the first input voltage Va is the minimum input voltage (i.e., the most negative one of the input voltages Va, Vb, and Vc), the second intermediate voltage Vz substantially follows the first input voltage Va. Equivalently, in the time period when the second input voltage Vb is the minimum input voltage, the second intermediate voltage Vz substantially follows the second input voltage Vb; and in the time period when the third input voltage Vc is the minimum input voltage, the second intermediate voltage Vz substantially follows the third input voltage Vc. Fig.15 It can be seen that within one third of one cycle of the input voltages Va, Vb, Vc, each of the input voltages Va, Vb, Vc is the minimum input voltage, so that the second intermediate voltage Vz also has a three-pulse waveform. There is a phase shift between the three-pulse shape waveforms of the first intermediate voltage Vx and the second intermediate voltage Vz, so that the total intermediate voltage (total DC link voltage) Vxz has a six-pulse waveform.

[0145] from Fig.15 It can be seen that in the first operation mode, the first output voltage portion Vp is lower than the first intermediate voltage Vx, and the amplitude of the second output voltage portion Vr is lower than the amplitude of the second intermediate voltage Vz, so that the power converter device operates in the first operation mode.

[0146] According to one example, the power converter device is also capable of operating in a second operating mode. When the first output voltage portion Vp is higher than the maximum switch node voltage reference Vmax*, and the magnitude of the second output voltage portion Vr is higher than the magnitude of the minimum switch node voltage reference Vmin*, the power converter device operates in the second operating mode. In this case, Fig.10 The first intermediate voltage reference controller 37x shown in FIG. outputs the measured first output voltage portion Vp' as the first intermediate voltage reference Vx*, and the second intermediate voltage reference controller 37z outputs the measured second output voltage portion Vr' as the second intermediate voltage reference Vz*. In this operation mode, each of the three converter stages 10a, 10b, 10c operates in a switching mode, so that the operation mode of the first power converter 1 can be referred to as a 3 / 3 mode.

[0147] In the second operating mode, the first converter stage 2p and the second converter stage 2r of the second power converter 2 can be deactivated in such a way that the switches 27p, 27r in each of the first converter stage 2p and the second converter stage 2r are permanently turned on. In this operating mode, the output voltage Vout and the total DC link voltage Vxz are regulated only by operating the first power converter 1.

[0148] Fig.16 A signal diagram illustrating operation of a power converter device in a second operating mode is shown. More specifically, Fig.16 The signal diagrams of the following items within one cycle of the input voltage Va, Vb, Vc are shown: input voltage Va, Vb, Vc; input current Ia, Ib, Ic; output voltage Vout, which is equal to the total DC link voltage Vxz; first intermediate voltage Vx, which is equal to the first output voltage portion Vp; equal magnitudes of the second intermediate voltage Vz and the second output voltage portion Vr; maximum switch node voltage reference Vmax*; minimum switch node voltage reference Vmin* magnitude; and ground current Iyn. As shown from Fig.16 It can be seen from FIG. 1 that each of the input currents Ia, Ib, and Ic has the same waveform as the corresponding input voltage Va, Vb, and Vc, so that the power converter device has a PFC function. Fig.16 As can be seen in FIG. 1 , the first and second intermediate voltages Vx and Vz and the first and second output voltage portions Vp and Vr vary as a result of adjusting the ground current Iyn or the ground voltage Vyn to zero.

[0149] There may be a transition phase when the output voltage increases from a voltage level at which the power converter device operates in the first operating mode to a voltage level at which the power converter device operates in the second operating mode. Fig.17 The signal diagram shown in FIG.

[0150] In the transition phase, there is a time period during which the first output voltage portion Vp is lower than the maximum switch node voltage reference Vmax*, so that the second power converter 2 adjusts the first intermediate voltage Vx to be substantially equal to the maximum switch node voltage reference Vmax*. In addition, in the transition phase, there is a time period during which the first output voltage portion Vp is higher than the maximum switch node voltage reference Vmax*, so that the second power converter 2 is deactivated and the first intermediate voltage Vx is equal to the first output voltage portion Vp.

[0151] In the transition phase, there is also a time period in which the amplitude of the second output voltage portion Vr is lower than the amplitude of the minimum switch node voltage reference Vmin*, so that the second power converter 2 adjusts the second intermediate voltage Vz to be substantially equal to the minimum switch node voltage reference Vmin*. In addition, in the transition phase, there is a time period in which the amplitude of the second output voltage portion Vr is higher than the amplitude of the minimum switch node voltage reference Vmin*, so that the second power converter 2 is driven and the second intermediate voltage Vz is equal to the second output voltage portion Vr.

[0152] In the transition phase of the power converter arrangement, at each time, one of the three converter stages 10a, 10b, 10c operates statically. Hence, the operating mode of the first power converter 1 in the transition phase may be referred to as 2 / 3 mode.

[0153] Some of the aspects described above are briefly summarized below with reference to numbered examples.

[0154] Example 1. A method comprising: operating a power converter device in a first operating mode, wherein the power converter device comprises: a first power converter comprising input nodes each configured to receive a corresponding one of input voltages, the input voltages each being referenced to a first ground node, and the first power converter being configured to provide a first intermediate voltage and a second intermediate voltage each being referenced to a second ground node; a second power converter connected between the first power converter and an output terminal of the power converter device, and wherein operating the power converter device in the first operating mode comprises: adjusting an input power received by the first power converter from the input node according to an output signal and according to a ground signal, and adjusting the first intermediate voltage by the second power converter each of a voltage and a second intermediate voltage, wherein the ground signal is a signal between the first ground node and the second ground node, wherein adjusting the input power includes: obtaining a switch node voltage reference based on the output signal and the ground signal, wherein adjusting the first intermediate voltage includes: selecting a maximum switch node voltage reference among the obtained switch node voltage references, and adjusting the first intermediate voltage so that the first intermediate voltage tracks the maximum switch node voltage reference among the obtained switch node voltage references, and wherein adjusting the second intermediate voltage includes: selecting a minimum switch node voltage reference among the obtained switch node voltage references, and adjusting the second intermediate voltage so that the second intermediate voltage tracks the minimum switch node voltage reference among the obtained switch node voltage references.

[0155] Example 2. A method according to Example 1, wherein an output voltage having a first output voltage portion and a second output voltage portion can be obtained at an output terminal, and wherein, in a first operating mode, the amplitude of the first output voltage portion is lower than the amplitude of a maximum switching node voltage reference, and the amplitude of the second output voltage portion is lower than the amplitude of a minimum switching node voltage reference.

[0156] Example 3. The method according to Example 2 further includes: operating the power converter device in a second operating mode when the amplitude of the first output voltage portion is higher than the amplitude of the maximum switching node voltage reference and the amplitude of the second output voltage portion is higher than the amplitude of the minimum switching node voltage reference, wherein operating the power converter device in the second operating mode includes: deactivating the second power converter.

[0157] Example 4. The method of any one of Examples 1 to 3, wherein the output signal is an output current of the power converter device.

[0158] Example 5. The method of any one of Examples 1 to 3, wherein the output signal is an output voltage of the power converter device.

[0159] Example 6. The method of any one of Examples 1 to 5, wherein the ground signal is a voltage between a first ground node and a second ground node.

[0160] Example 7. The method of any one of Examples 1 to 5, wherein the ground signal is a current between the first ground node and the second ground node.

[0161] Example 8. A method according to any of the preceding examples, wherein the second power converter includes a first converter stage and a second converter stage, and wherein adjusting each of the first intermediate voltage and the second intermediate voltage by the second power converter includes: adjusting the first intermediate voltage by the first converter stage and adjusting the second intermediate voltage by the second converter stage.

[0162] Example 9. The method of Example 8, wherein each of the first converter stage and the second converter stage comprises a buck converter.

[0163] Example 10. A method according to any of the preceding examples, wherein the first power converter includes converter stages, each of the converter stages being coupled to a corresponding one of the input nodes and each including a switch node between an inductor and a switch stage, wherein each of the switch node voltage references is a desired voltage between a switch node of a corresponding one of the converter stages and a first ground node or a second ground node.

[0164] Example 11. A controller configured to operate a power converter device in a first operating mode, wherein the power converter device includes: a first power converter including input nodes each configured to receive a corresponding one of input voltages, the input voltages each being referenced to a first ground node, and the first power converter is configured to provide a first intermediate voltage and a second intermediate voltage each being referenced to a second ground node; a second power converter connected between the first power converter and an output terminal of the power converter device, and wherein operating the power converter device in the first operating mode includes: adjusting an input power received by the first power converter from the input node according to an output signal and according to a ground signal, and adjusting the first intermediate voltage and the second intermediate voltage by the second power converter. Each of two intermediate voltages, wherein the ground signal is a signal between a first ground node and a second ground node, wherein adjusting the input power received by the first power converter includes: obtaining a switch node voltage reference based on the output signal and the ground signal, wherein adjusting the first intermediate voltage includes: selecting a maximum switch node voltage reference among the obtained switch node voltage references, and adjusting the first intermediate voltage so that the first intermediate voltage tracks the maximum switch node voltage reference among the obtained switch node voltage references, and wherein adjusting the second intermediate voltage includes: selecting a minimum switch node voltage reference among the obtained switch node voltage references, and adjusting the second intermediate voltage so that the second intermediate voltage tracks the minimum switch node voltage reference among the obtained switch node voltage references.

[0165] Example 12. A controller according to Example 11, wherein an output voltage having a first output voltage portion and a second output voltage portion can be obtained at the output, and wherein operating the power converter device in the first operating mode includes: operating the power converter device in the first operating mode when the amplitude of the first output voltage portion is lower than the amplitude of the maximum switching node voltage reference and the amplitude of the second output voltage portion is lower than the amplitude of the minimum switching node voltage reference.

[0166] Example 13. A controller according to Example 12, wherein the controller is further configured to: operate the power converter device in a second operating mode when the amplitude of the first output voltage portion is higher than the amplitude of the maximum switching node voltage reference, and the amplitude of the second output voltage portion is higher than the amplitude of the minimum switching node voltage reference, wherein operating the power converter device in the second operating mode includes: deactivating the second power converter.

[0167] Example 14. A controller according to any of Examples 11 to 13, wherein the output signal is one of an output current and an output voltage of the power converter device.

[0168] Example 15. A power converter device comprising: a first power converter, comprising input nodes each configured to receive a corresponding one of input voltages, the input voltages each being referenced to a first ground node, and the first power converter being configured to provide a first intermediate voltage and a second intermediate voltage each being referenced to a second ground node; a second power converter connected between the first power converter and an output terminal of the power converter device; and a controller according to any one of Examples 11 to 14.

Claims

1. A method for operating a power converter device, comprising: operating the power converter device in a first operating mode, Wherein, the power converter device comprises: A first power converter (1) comprising input nodes (a, b, c) each configured to receive a respective one of input voltages (Va, Vb, Vc), each of which is referenced to a first ground node (n), and the first power converter (1) is configured to provide a first intermediate voltage (Vx) and a second intermediate voltage (Vz) each of which is referenced to a second ground node (y); a second power converter connected between the first power converter (1) and the output terminal (p, r) of the power converter device, and Wherein, operating the power converter device in the first operation mode comprises: adjusting the input power received by the first power converter (1) from the input node (a, b, c) according to the output signal (Sout) and according to the ground signal (Syn), and adjusting each of the first intermediate voltage (Vx) and the second intermediate voltage (Vz) by the second power converter (2), The ground signal (Syn) is a signal between the first ground node (n) and the second ground node (y). Wherein, adjusting the input power includes obtaining a switch node voltage reference (Va\*, Vb\*, Vc\*) according to the output signal (Sout) and the ground signal (Syn), Wherein, adjusting the first intermediate voltage (Vx) includes: selecting the maximum switch node voltage reference (Vmax*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and adjusting the first intermediate voltage (Vx) so that the first intermediate voltage (Vx) tracks the maximum switch node voltage reference (Vmax*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and Wherein, adjusting the second intermediate voltage (Vz) includes: selecting the minimum switch node voltage reference (Vmin*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and adjusting the second intermediate voltage (Vz) so that the second intermediate voltage (Vz) tracks the minimum switch node voltage reference (Vmin*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*).

2. The method according to claim 1, in, An output voltage (Vout) having a first output voltage portion (Vp) and a second output voltage portion (Vr) can be obtained at the output terminal (p, r), and Wherein, in the first operating mode, the amplitude of the first output voltage portion (Vp) is lower than the amplitude of the maximum switching node voltage reference (Vmax*), and the amplitude of the second output voltage portion (Vr) is lower than the amplitude of the minimum switching node voltage reference (Vmin*).

3. The method according to claim 2, further comprising: operating the power converter device in a second operating mode when the magnitude of the first output voltage portion (Vp) is higher than the magnitude of the maximum switching node voltage reference (Vmax*) and the magnitude of the second output voltage portion (Vr) is higher than the magnitude of the minimum switching node voltage reference (Vmin*), Wherein, operating the power converter device in the second operation mode comprises: The second power converter (2) is deactivated.

4. The method according to any one of claims 1 to 3, wherein: The output signal (Sout) is the output current (Iout) of the power converter device.

5. The method according to any one of claims 1 to 3, wherein: The output signal (Sout) is the output voltage (Vout) of the power converter device.

6. The method according to any one of claims 1 to 5, in, The ground signal (Syn) is a voltage (Vyn) between the first ground node (n) and the second ground node (y).

7. The method according to any one of claims 1 to 5, in, The ground signal (Syn) is a current (Iyn) between the first ground node (n) and the second ground node (y).

8. The method according to any one of the preceding claims, in, The second power converter (2) comprises a first converter stage (20p) and a second converter stage (20r), and Wherein, adjusting each of the first intermediate voltage (Vx) and the second intermediate voltage (Vz) by the second power converter (2) includes: adjusting the first intermediate voltage (Vx) by the first converter stage (20p) and adjusting the second intermediate voltage (Vz) by the second converter stage (20r).

9. The method according to claim 8, in, Each of the first converter stage (20p) and the second converter stage (20r) comprises a buck converter.

10. The method according to any one of the preceding claims, in, The first power converter (1) comprises a converter stage (10a, 10b, 10c), each of the converter stages (10a, 10b, 10c) being coupled to a corresponding one of the input nodes (a, b, c) and each comprising a switch node (a\, b\, c\) between an inductor (11a, 11b, 11c) and a switch stage (12a, 12b, 12c), wherein each of the switch node voltage references (Va\*, Vb\*, Vc\*) is a desired voltage between the switch node (a\, b\, c\) of a corresponding one of the converter stages (10a, 10b, 10c) and the first ground node (n) or the second ground node (y).

11. A controller configured to operate a power converter device in a first operating mode, in, The power converter device comprises: A first power converter (1) comprising input nodes (a, b, c) each configured to receive a respective one of input voltages (Va, Vb, Vc), each of which is referenced to a first ground node (n), and the first power converter (1) is configured to provide a first intermediate voltage (Vx) and a second intermediate voltage (Vz) each of which is referenced to a second ground node (y); a second power converter connected between the first power converter (1) and the output terminal (p, r) of the power converter device, and Wherein, operating the power converter device in the first operation mode comprises: adjusting the input power received by the first power converter (1) from the input node (a, b, c) according to the output signal (Sout) and according to the ground signal (Syn), and each of the first intermediate voltage (Vx) and the second intermediate voltage (Vz) is adjusted by the second power converter (2), The ground signal (Syn) is a signal between the first ground node (n) and the second ground node (y). Wherein, adjusting the input power received by the first power converter (1) comprises obtaining a switch node voltage reference (Va\*, Vb\*, Vc\*) according to the output signal (Sout) and the ground signal (Syn), Wherein, adjusting the first intermediate voltage (Vx) includes: selecting the maximum switch node voltage reference (Vmax*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and adjusting the first intermediate voltage (Vx) so that the first intermediate voltage (Vx) tracks the maximum switch node voltage reference (Vmax*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and Wherein, adjusting the second intermediate voltage (Vz) includes: selecting the minimum switch node voltage reference (Vmin*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*), and adjusting the second intermediate voltage (Vz) so that the second intermediate voltage (Vz) tracks the minimum switch node voltage reference (Vmin*) among the obtained switch node voltage references (Va\*, Vb\*, Vc\*).

12. The controller according to claim 11, in, An output voltage (Vout) having a first output voltage portion (Vp) and a second output voltage portion (Vr) can be obtained at the output terminal (p, r), and Wherein, operating the power converter device under the first operating mode includes: when the amplitude of the first output voltage part (Vp) is lower than the amplitude of the maximum switching node voltage reference (Vmax*), and the amplitude of the second output voltage part (Vr) is lower than the amplitude of the minimum switching node voltage reference (Vmin*), operating the power converter device under the first operating mode.

13. The controller according to claim 12, in, The controller is further configured to operate the power converter device in a second operating mode when the magnitude of the first output voltage portion (Vp) is higher than the magnitude of the maximum switching node voltage reference (Vmax*) and the magnitude of the second output voltage portion (Vr) is higher than the magnitude of the minimum switching node voltage reference (Vmin*), Wherein, operating the power converter device in the second operation mode comprises: The second power converter (2) is deactivated.

14. A controller according to any one of claims 11 to 13, wherein: The output signal (Sout) is one of an output current (Iout) and an output voltage (Vout) of the power converter device.

15. A power converter device comprising: A first power converter (1) comprising input nodes (a, b, c) each configured to receive a respective one of input voltages (Va, Vb, Vc), each of which is referenced to a first ground node (n), and the first power converter (1) is configured to provide a first intermediate voltage (Vx) and a second intermediate voltage (Vz) each of which is referenced to a second ground node (y); a second power converter connected between the first power converter (1) and an output terminal (p, r) of the power converter device; and A controller according to any one of claims 11 to 14.

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