DE102019208033A1 - Power unit, inverter and process - Google Patents

Abstract

Shown and described is a power unit (1) with a first input connection (3) and a second input connection (5) to which an input voltage can be applied, a first output connection (7) and a second output connection (9), of which an output voltage for supplying an electrical load (21) can be provided, a switching unit (17) with several switching elements (31, 33, 35, 37, 39, 41), and an oscillating circuit (15) with a coil (27) and a Capacitor (29), wherein a first switching element (31) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the first input connection (3) and the first output connection (7), with a second switching element ( 33) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the second input connection (5) and the first output connection (7), a third switching element (35) of the plurality of switching elements (31, 33, 35, 37, 39, 41) with the first egg input connection (3) and the second output connection (9) is connected, wherein a fourth switching element (37) of the plurality of switching elements (31, 33, 35, 37, 39, 41) with the second input connection (5) and the second output connection (9 ) is connected, the resonant circuit (15) being connected to the first input connection (3) and the second input connection (5).

Description

The present invention relates to a power unit, an inverter with a power unit and a method for controlling a power unit.

Inverters with line units are known from the prior art. Input voltages can be applied to the power units, which can be converted into output voltages with the aid of switching elements of the power unit. For the conversion of an input voltage into an output voltage, the switching elements are usually switched in a mutually coordinated manner, each of the switching elements being able to assume an electrically conductive state and an electrically insulating state.

When switching a switching element, both during the transition from the electrically conductive state of the switching element to the electrically insulating state of the switching element and during the transition from the electrically insulating state of the switching element to the electrically conductive state of the switching element, power loss can occur in the switching element. In particular at high switching frequencies, this power loss can significantly reduce the efficiency of the power unit.

It is desirable to provide power units with high efficiencies. At the same time, it is desirable to provide power units with a small number of components.

It is therefore the object of the present invention to provide a power unit with a high degree of efficiency which has a small number of components. It is also the object of the present invention to provide an inverter with a corresponding power unit and a method for controlling a corresponding power unit.

According to a first aspect of the invention, the stated object is achieved by a power unit with the features of claim 1. The power unit has a first input connection and a second input connection. An input voltage can be applied to the first input connection and to the second input connection. The power unit has a first output connection and a second output connection. An output voltage for supplying an electrical load can be provided by the first output connection and the second output connection. The power unit has a switching unit. The switching unit has several switching elements. The power unit has an oscillating circuit. The resonant circuit has a coil and a capacitor. A first switching element of the plurality of switching elements is connected to the first input terminal and the first output terminal. A second switching element of the plurality of switching elements is connected to the second input terminal and the first output terminal. A third switching element of the plurality of switching elements is connected to the first input terminal and the second output terminal. A fourth switching element of the plurality of switching elements is connected to the second input terminal and the second output terminal. The resonant circuit is connected to the first input connection and the second input connection.

The power unit has the first input connection and the second input connection. The first input connection and the second input connection can each provide an electrical contact. A voltage source can be connected to the first input connection and the second input connection, so that an electrical connection is provided between the voltage source and the power unit. The voltage source can be an accumulator or a battery.

The input voltage can be applied to the first input connection and the second input connection. In particular, when the voltage source is connected to the first input connection and the second input connection, the input voltage can be provided by the voltage source so that the input voltage is applied to the first input connection and to the second input connection. The input voltage can, however, also be an intermediate circuit voltage. If the input voltage is an intermediate circuit voltage, an electrical circuit, in particular a further power unit connected upstream of the line unit, is connected to the first input connection and the second input connection, so that the electrical circuit provides the input voltage.

The input voltage is preferably a direct voltage. In particular, the instantaneous value of the input voltage does not change over a longer observation period. The instantaneous value of the input voltage can also change over time, in particular change periodically. However, if the instantaneous value of the input voltage changes over time, the input voltage does not change its polarity.

The power unit has a first output connection and a second output connection. The first output port and the second output connection can each provide an electrical contact. The electrical consumer can be connected to the first output connection and the second output connection, so that an electrical connection is provided between the power unit and the electrical consumer, so that a working current can flow through the electrical consumer. When the term consumer is used in the following, it refers to the electrical consumer.

If the consumer is connected to the first output connection and the second output connection, an output voltage for supplying the consumer can be provided by the first output connection and the second output connection, so that the working current can flow through the consumer. The consumer can be an electric motor, in particular a brushless electric motor.

The output voltage is preferably an alternating voltage. In particular, the instantaneous value of the output voltage changes over a longer observation period. The instantaneous value of the output voltage preferably changes periodically. In particular, the instantaneous value of the output voltage changes over time in such a way that the output voltage changes its polarity repeatedly over time. In particular, the recurring change in the polarity of the output voltage over time is achieved by the way in which the switching elements are switched in a coordinated manner.

The power unit has a switching unit which has a plurality of switching elements. Each switching element of the switching elements can be a transistor, in particular a power transistor. If a switching element is a power transistor, the corresponding switching element is preferably designed so that a maximum collector current or a maximum drain current is at least 1 A. Alternatively or additionally, a switching element embodied as a power transistor can be embodied, so that a minimum collector-emitter voltage or a minimum drain-source voltage is at least 50 V. Each of the switching elements can be a field effect transistor. Field effect transistors have the advantage that they enable control with a low power requirement. Preferably, each of the switching elements is an insulated gate field effect transistor (IGFET). Each of the switching elements is particularly preferably a metal-oxide-semiconductor field effect transistor (MOSFET). Each of the switching elements can also be a bipolar transistor (BJT). Bipolar transistors have the advantage that they can be designed for high currents and high voltages. Each of the switching elements is preferably a bipolar transistor with an insulated gate electrode (IGBT). Bipolar transistors with an insulated gate electrode provide good on-state behavior, high blocking voltages, high robustness and control with low power requirements. Each of the switching elements can also be a thyristor.

Each of the switching elements can assume an electrically conductive state and an electrically insulating state. When a switching element is in the electrically conductive state, an operating current can flow through the corresponding switching element. When the corresponding switching element is in the electrically insulating state, the working current cannot flow through the corresponding switching element. A corresponding switching process can be used to switch between the electrically conductive state and the electrically insulating state of each switching element. Each of the switching elements can be switched such that the corresponding switching element is in a corresponding electrically conductive state during a switch-on period and is in a corresponding electrically insulating state during a switch-off period.

In connection with the present invention, a distinction must be made between the working current that flows through the consumer and the working current that flows through the switching elements. In particular, the working current flowing through the consumer changes its direction, the working current flowing through the switching elements not changing its direction. This is achieved in particular by the coordinated switching of the switching elements. The features, technical effects and / or advantages described in connection with the working current flowing through the switching elements also apply at least in an analogous manner to each working current flowing through a corresponding switching element and vice versa. In particular, the oscillating working current means the working current that flows through the switching elements.

The first switching element of the plurality of switching elements is connected to the first input terminal and the first output terminal. The connection of the first switching element to the first input terminal enables an electrical connection between the first switching element and the voltage source when the voltage source is connected to the first input terminal. The connection of the first switching element to the first output connection enables an electrical connection between the first switching element and the consumer when the consumer is connected to the first output connection.

The second switching element of the plurality of switching elements is connected to the second input terminal and the first output terminal. The connection of the second switching element to the second input terminal enables an electrical connection between the second switching element and the voltage source when the voltage source is connected to the second input terminal. The connection of the second switching element to the first output connection enables an electrical connection between the second switching element and the consumer when the consumer is connected to the first output connection.

The third switching element of the plurality of switching elements is connected to the first input terminal and the second output terminal. The connection of the third switching element to the first input terminal enables an electrical connection between the third switching element and the voltage source when the voltage source is connected to the first input terminal. The connection of the third switching element to the second output connection enables an electrical connection between the third switching element and the consumer when the consumer is connected to the second output connection.

The fourth switching element of the plurality of switching elements is connected to the second input terminal and the second output terminal. The connection of the fourth switching element to the second input terminal enables an electrical connection between the fourth switching element and the voltage source when the voltage source is connected to the second input terminal. The connection of the fourth switching element to the second output connection enables an electrical connection between the fourth switching element and the consumer when the consumer is connected to the second output connection.

The power unit has an oscillating circuit which is connected to the first input connection and the second input connection. The connection of the resonant circuit to the first input connection and the second input connection enables an electrical connection between the resonant circuit and the voltage source when the voltage source is connected to the first input connection and the second input connection.

The resonant circuit has a coil and a capacitor. The resonant circuit can be excited to an electrical oscillation. For example, the resonant circuit can be excited to oscillate electrically by switching at least one switching element of the plurality of switching elements. When the resonant circuit is excited to the electrical oscillation, energy can be exchanged periodically between the electric field of the capacitor and the magnetic field of the coil. The electrical oscillation of the resonant circuit can lead to an oscillation of the working current, which can flow through the multiple switching elements that are connected to one another. In particular, the oscillating operating current can flow at a given point in time through two switching elements, each of which is in the electrically conductive state. The working current flowing through the switching elements preferably oscillates at a resonance frequency of the resonant circuit.

The working current flowing through the switching elements can in particular oscillate in such a way that the instantaneous value of the working current changes over time, in particular changes periodically. The working current flowing through the switching elements preferably oscillates around a mean value of the working current flowing through the switching elements so that the instantaneous value of the working current repeatedly falls below and exceeds the mean value one after the other, in particular when the electrical current direction of the working current flowing through the switching elements remains the same. The mean value of each operating current flowing through a switching element is preferably not equal to zero. A mean value not equal to zero can be achieved in that the electrical current direction of each operating current flowing through a switching element remains the same. The working current flowing through a switching element can have a direct current component and an alternating current component which are superimposed on one another, so that each working current flowing through a switching element oscillates. During a corresponding switch-on period of each of the switching elements, the corresponding switching element is electrically conductive, so that the oscillating working current can flow through the corresponding switching element.

Due to the way in which the switching elements are switched, the instantaneous value of the working current flowing through the consumer changes over a longer observation period. The instantaneous value of the working current flowing through the consumer preferably changes periodically. In particular, the instantaneous value of the working current flowing through the consumer changes over time such that the working current flowing through the consumer repeatedly changes its direction over time.

As already described, the working current flowing through the switching elements oscillates, the oscillation of the working current flowing through the switching elements being caused by the resonant circuit becomes. The oscillation of the working current flowing through the switching elements enables each of the switching elements to be controlled in such a way that the end of a corresponding switch-on period of a corresponding switching element, during which the corresponding switching element is electrically conductive, lies in the time range of a minimum of the oscillating working current or even with it the minimum of the oscillating working current coincides in time. The current strength of the oscillating working current flowing through the corresponding switching element is thus less than the current strength of a non-oscillating working current during the transition from the electrically conductive state to the electrically insulating state of the switching element. Due to the low current intensity during the transition from the electrically conductive state to the electrically insulating state of the switching element, the power loss during the transition from the electrically conductive state to the electrically insulating state of the switching element can be significantly reduced, so that a high efficiency of the power unit, especially with high switching frequencies can be achieved. Furthermore, the resonant circuit with the coil and the capacitor is a comparatively low-component solution.

In summary, it can be stated that a power unit with a high degree of efficiency and a small number of components is made possible.

In one embodiment, the coil of the resonant circuit and the capacitor of the resonant circuit form a parallel circuit, the coil being connected to the first input connection and the second input connection, the capacitor being connected to the first input connection and the second input connection. The parallel connection forms a preferred embodiment of the resonant circuit with a parallel resonant circuit.

In one embodiment, the coil of the resonant circuit and the capacitor of the resonant circuit form a series circuit, the coil being connected to the first input connection and the capacitor being connected to the second input connection. The series connection, which can be referred to as the first series connection, forms a preferred embodiment of the resonant circuit with a series resonant circuit.

In one embodiment, the coil of the resonant circuit and the capacitor of the resonant circuit form a series circuit, the coil being connected to the second input connection and the capacitor being connected to the first input connection. The series connection, which can be referred to as a second series connection, forms a further preferred embodiment of the resonant circuit with a series resonant circuit.

In one embodiment, the power unit has a third output terminal, wherein a fifth switching element of the plurality of switching elements is connected to the first input terminal and the third output terminal, wherein a sixth switching element of the plurality of switching elements is connected to the second input terminal and the third output terminal. The fifth switching element of the plurality of switching elements is connected to the first input terminal and the third output terminal. The connection of the fifth switching element to the first input terminal enables an electrical connection between the fifth switching element and the voltage source when the voltage source is connected to the first input terminal. The connection of the fifth switching element to the third output connection enables an electrical connection between the fifth switching element and the consumer when the consumer is connected to the third output connection. The sixth switching element of the plurality of switching elements is connected to the second input terminal and the third output terminal. The connection of the sixth switching element to the second input connection enables an electrical connection between the sixth switching element and the voltage source when the voltage source is connected to the second input connection. The connection of the sixth switching element to the third output connection enables an electrical connection between the sixth switching element and the consumer when the consumer is connected to the third output connection.

In one embodiment, the power unit has an energy store, which is connected to the first input connection and the second input connection. If an input voltage source is connected to the first input connection and to the second input connection, the energy store can be supplied with charge carriers from the input voltage source and thus energy can be temporarily stored in the energy store. In the event that the consumer has a short-term high energy requirement, the charge carriers stored by the energy store can be released by the latter, so that sufficient charge carriers can be provided for the short-term high energy demand. The energy store can have at least one capacitor. The capacitor can carry electrical charges electrostatically save and thus release them at short notice. The at least one capacitor can have two capacitors. The two capacitors can form a series circuit such that one of the two capacitors is connected to the first input terminal and the other of the two capacitors is connected to the second input terminal. The two capacitors preferably form a parallel circuit, so that each of the two capacitors is connected to both the first input connection and the second input connection. The parallel connection of the two capacitors can increase the capacity of the energy store. Each of the at least one capacitor can be an electrolytic capacitor. An electrolytic capacitor can have a comparatively high capacitance in relation to its size.

According to a second aspect of the invention, the object mentioned at the beginning is achieved by an inverter having the features of claim 7. The inverter has a power unit according to the first aspect of the invention and a control unit. The control unit is connected to the multiple switching elements of the switching unit for controlling the multiple switching elements. The control unit can provide a corresponding control signal for each switching element, so that each of the switching elements can transition from a corresponding electrically conductive state to a corresponding electrically insulating state and from the corresponding electrically insulating state to the corresponding electrically conductive state, depending on the corresponding control signal .

The power unit according to the first aspect of the invention or the inverter according to the second aspect of the invention can have a measuring unit for measuring the operating current flowing through the at least one switching element. In particular, the period duration of the oscillating operating current can be determined with the aid of the measuring unit. Furthermore, the mean value of the working current flowing through the switching elements can be determined with the measuring unit. In addition, a minimum or several minimums of the operating current flowing through the switching elements can be determined with the measuring unit.

The features, technical effects and / or advantages described in connection with the power unit according to the first aspect of the invention also apply at least in an analogous manner to the inverter according to the second aspect of the invention, so that a corresponding repetition is dispensed with at this point.

According to a third aspect of the invention, the aforementioned object is achieved by a method with the features of claim 8. The method is carried out for controlling a power unit according to the first aspect of the invention. Each of the switching elements is switched in such a way that each of the switching elements is electrically conductive during a corresponding switch-on period, so that an oscillating operating current can flow through the switching element, and is electrically insulating during a corresponding switching-off period, so that the oscillating operating current cannot flow through the switching element. At least one of the switching elements is controlled in such a way that the end of a corresponding switch-on period of the at least one switching element lies in a time interval which is at most a quarter of a period of the oscillating working current and in which there is a minimum of the oscillating working current. The oscillation of the oscillating working current is caused by the resonant circuit, so that the working current oscillates at the resonance frequency of the resonant circuit.

Each of the switching elements is switched in such a way that each of the switching elements is electrically conductive during a corresponding switch-on period, so that an oscillating operating current can flow through the switching element, and is electrically insulating during a corresponding switching-off period, so that the oscillating operating current cannot flow through the switching element. In particular, each of the switching elements can be switched in such a way that several switch-on periods and several switch-off periods follow one another, so that in each case a switch-off period follows a corresponding switch-on period and a switch-on period follows a corresponding switch-off period, so that each of the switching elements switches between a corresponding electrically conductive state and a corresponding one electrically insulating state changes back and forth.

At least one of the switching elements is controlled in such a way that the end of the corresponding switch-on period of the at least one switching element lies in the time interval which is at most a quarter of the period of the oscillating working current and in which the minimum of the oscillating working current is. The end of the switch-on period and the minimum of the oscillating working current lie in the time interval so that the end of the switched-on period and the minimum of the oscillating working current are close in time or, particularly preferably, coincide in time. The instantaneous value of the oscillating operating current is therefore particularly low during the transition from the electrically conductive state to the electrically insulating state of the at least one switching element, so that the power loss is also particularly low. Thus, a method of controlling a power unit with a high Efficiency and a small number of components allows.

The time interval is preferably at most one fifth, one tenth or one hundredth of the period of the oscillating working current. The smaller the time interval selected, the lower the instantaneous value of the oscillating operating current at the point in time at the end of the switch-on period. It is particularly preferred that the end of the corresponding switch-on period of the at least one switching element and the minimum of the oscillating operating current coincide in time. In this case, the instantaneous value of the oscillating operating current during the transition from the electrically conductive state to the electrically insulating state of the at least one switching element is particularly low, so that the power loss in the switching element is also particularly low. The minimum of the oscillating working current can be a local minimum of the oscillating working current. In particular, the minimum of the oscillating working current is the lowest instantaneous value of the oscillating working current during a period of the oscillating working current.

The instantaneous value of the oscillating operating current can be determined by the measuring unit. The instantaneous value of the oscillating working current during the time interval is preferably less than a mean value around which the working current oscillates. In particular, the at least one switching element is controlled in such a way that the switching element changes from the electrically conductive state to the electrically insulating state when the instantaneous value of the oscillating operating current falls below a predetermined threshold value, so that the end of the corresponding switch-on period of the at least one switching element lies within the time interval. In particular, the threshold value is greater than the minimum of the oscillating working current, preferably 10% or 5% or 2% of the amplitude of the oscillating working current is greater than the minimum of the oscillating working current.

In one embodiment, the at least one switching element is controlled in such a way that the switch-on duration of the at least one switching element is a first multiple of the period duration of the operating current flowing through the at least one switching element. The first multiple can change over time in accordance with a duty cycle of the control signal. The first multiple can be, for example, one, two, three, four or five.

In one embodiment, the at least one switching element is controlled in such a way that the switch-off period of the at least one switching element is a second multiple of the period duration of the operating current that flows through the at least one switching element during the switch-on period. The second multiple can change over time according to the duty cycle of the control signal. The second multiple can be, for example, one, two, three, four or five.

In one embodiment, each of the switching elements is controlled in such a way that the end of a corresponding switch-on period of each of the switching elements lies in a corresponding time interval which is at most a quarter of the period of the oscillating operating current and in which there is a corresponding minimum of the oscillating operating current. Each of the switching elements can thus be controlled in such a way that a particularly high level of efficiency of the power unit is achieved.

In one embodiment, each of the switching elements is controlled in such a way that the corresponding switch-on duration of each of the switching elements is a corresponding first multiple of the period duration of the operating current flowing through the corresponding switching element. Each first multiple can change over time in accordance with a duty cycle of the corresponding control signal. Each first multiple can be, for example, one, two, three, four or five.

In one embodiment, each of the switching elements is controlled in such a way that the corresponding switch-off period of each of the switching elements is a corresponding second multiple of the period duration of the operating current that flows through the corresponding switching element during the corresponding switch-on period. Every second multiple can change over time in accordance with a duty cycle of the corresponding control signal. Every other multiple can be, for example, one, two, three, four or five.

The features, technical effects and / or advantages described in connection with the power unit according to the first aspect of the invention and the features, technical effects and / or advantages described in connection with the inverter according to the second aspect of the invention also apply at least in an analogous manner to the method according to the third aspect of the invention, so that a corresponding repetition is dispensed with at this point.

• 1 zeigt eine schematische Ansicht einer Ausführungsform einer erfindungsgemäßen Leistungseinheit.
• 2 zeigt eine schematische Ansicht eines zeitlichen Verlaufs eines Steuersignals eines ersten Schaltelements der Leistungseinheit in 1 sowie eines zeitlichen Verlaufs eines Arbeitsstroms durch das erste Schaltelement.
• 3 zeigt einen Ausschnitt aus 2.

Further features, advantages and possible applications of the present invention emerge from the following description of the exemplary embodiments and the figures. All of the features described and / or shown in the figures, individually and in any combination, form the subject matter of the invention, regardless of their composition in the individual claims or their references. In the figures continue to represent the same reference symbols for the same or similar objects.

• 1 shows a schematic view of an embodiment of a power unit according to the invention.
• 2 FIG. 13 shows a schematic view of a time profile of a control signal of a first switching element of the power unit in FIG 1 and a time profile of an operating current through the first switching element.
• 3 shows an excerpt from 2 .

1 shows a schematic view of an embodiment of a power unit according to the invention 1 . The power unit 1 has a first input port 3 and a second input port 5 on. The power unit 1 has a first output port 7th , a second output port 9 and a third output terminal 11 on. It also has the power unit 1 an energy store 13 , an oscillating circuit 15th and a switching unit 17th on.

Furthermore shows 1 a voltage source 19th . The voltage source 19th is with the first input port 3 and the second input port 5 connected. The voltage source 19th provides an input voltage that is applied to the first input terminal 3 and the second input port 5 is applied. Also shows 1 a consumer 21st . The consumer 21st is with the first output port 7th , the second output port 9 and the third output terminal 11 connected.

The energy storage 13 is with the first input port 3 and the second input port 5 connected. The energy storage 13 has two capacitors 23 , 25th on. A first capacitor 23 of the two capacitors 23 , 25th is with the first input port 3 connected. A second capacitors 25th of the two capacitors 23 , 25th is to the second input port 5 connected. The two capacitors 23 , 25th form a series circuit. The first capacitor 23 of the energy storage 13 is designed as an electrolytic capacitor. Likewise the second is capacitors 25th of the energy storage 13 designed as an electrolytic capacitor. The energy storage 13 can from the voltage source 19th are supplied with charge carriers and are thus supplied with energy. When the consumer 21st has a high energy demand for a short time, the energy storage 13 stored charge carriers are released by this, so that sufficient charge carriers can be provided for the short-term high energy demand.

The oscillating circuit 15th has a coil 27 and a capacitor 29 on. The oscillating circuit 15th is with the first input port 3 and the second input port 5 connected. In 1 form the coil 27 of the oscillating circuit 15th and the capacitor 29 of the oscillating circuit 15th a parallel connection. Both the coil 27 as well as the capacitor 29 are each connected to the first input port 3 and the second input port 5 connected. Alternatively, the coil 27 and the capacitor 29 form a series circuit. In this case the coil can 27 with the first input port 3 be connected and the capacitor 29 to the second input port 5 be connected. The sink 27 can also be used with the second input connector 5 and the capacitor 29 with the first input port 3 be connected.

The switching unit 17th has a first switching element 31 , a second switching element 33 , a third switching element 35 , a fourth switching element 37 , a fifth switching element 39 and a sixth switching element 41 on. The first switching element 31 is with the first input port 3 and the first output terminal 7th connected. The second switching element 33 is to the second input port 5 and the first output terminal 7th connected. The third switching element 35 is with the first input port 3 and the second output terminal 9 connected. The fourth switching element 37 is to the second input port 5 and the second output terminal 9 connected. The fifth switching element 39 is with the first input port 3 and the third output terminal 11 connected. The sixth switching element 41 is to the second input port 5 and the third output terminal 11 connected.

The energy storage 13 is with the resonant circuit 15th via two connections 43 connected. The oscillating circuit 15th is with the switching unit 17th also via two connections 43 connected. The electrical potential at the in 1 connections shown above 43 can essentially be the potential at the first input terminal 3 correspond. The electrical potential at the in 1 connections shown below 43 can essentially be the potential at the second input terminal 5 correspond. In connection with the present invention, a first electrical potential at a first location can essentially correspond to a second electrical potential at a second location if the first location and the second location are connected to one another via electrical lines.

In the 1 power unit shown 1 can be part of an inverter. The inverter can use an in 1 have not shown control unit with the plurality of switching elements 31 , 33 , 35 , 37 , 39 , 41 the switching unit 17th to control the multiple switching elements 31 , 33 , 35 , 37 , 39 , 41 connected is. The multiple switching element 31 , 33 , 35 , 37 , 39 , 41 are controlled in such a way that they are switched in a coordinated manner. Each of the switching elements 31 , 33 , 35 , 37 , 39 , 41 each assume an electrically conductive state and an electrically insulating state.

2 shows a schematic view of a time profile of a control signal 45 of the first switching element 31 the power unit 1 in 1 as well as a time profile of an operating current 47 by the first switching element 31 . The one in connection with the first switching element 31 features, technical effects and / or advantages described, in particular of the control signal 45 and the working current 47 apply at least in an analogous manner to each other of the plurality of switching elements 31 , 33 , 35 , 37 , 39 , 41 , in particular for the second, third, fourth, fifth and sixth switching element 33 , 35 , 37 , 39 , 41 . The 2 is to be understood purely schematically. The control signals are only for a better illustration 45 and the working current 47 shown in a diagram over time and are shown so that both have the same amplitude.

Using the control signal 45 can the first switching element 31 be switched such that the first switching element 31 during a switch-on period 49 is electrically conductive and during a switch-off period 51 is electrically insulating. In 2 are several switch-on times 49 and several switch-off times 51 shown, which follow one another, so that each time a switch-off period 51 to a corresponding switch-on time 49 and one duty cycle each 49 for a corresponding switch-off time 51 follows. The control signal 45 is pulse width modulated, so that each time a duty cycle 49 with a switch-off time immediately following it 51 a period 53 of the control signal 45 forms. According to a duty cycle of the control signal that changes over time 45 differ in 2 switch-on times shown 49 and switch-off times 51 .

The work stream 47 oscillates with a period 55 around a mean 57 and runs through several minima 59 . The oscillation of the oscillating working current 47 is from the resonant circuit 15th caused so that the working current 47 with the resonance frequency of the oscillating circuit 15th oscillates.

wobei L die Induktivität der Spule 27 und C die Kapazität des Kondensator 29 ist.The resonance frequency of the oscillating circuit 15th is: $$f_0=\frac{1}{2\pi \sqrt{\mathrm{L.}\mathrm{C.}}},$$

where L is the inductance of the coil 27 and C is the capacitance of the capacitor 29 is.

The first switching element 31 can be switched to operate during each of the on-time periods 49 is electrically conductive, so that the oscillating working current 47 by the first switching element 31 can flow. The first switching element 31 is during each of the switch-off times 51 electrically isolating, so that the oscillating working current 47 not by the first switching element 31 can flow.

$$t_2=m\frac{1}{f_0}.$$

The first switching element 31 is controlled in such a way that the switch-on time 49 of the first switching element 31 a first multiple n of the period 55 of the working current 47 by the first switching element 31 is. The first multiple changes over time according to the duty cycle of the control signal 45 . In 2 a first multiple from left to right of five, four, three, two and one is shown as an example. In addition, the first switching element 31 controlled in such a way that the switch-off time 51 of the first switching element 31 a second multiple m of the period 55 of the working current 47 is that during the switch-on period 49 by the first switching element 31 flows. The second multiple changes over time according to the duty cycle of the control signal 45 . In 2 a second multiple from left to right of one, two, three, four and five is shown as an example. Each of the on-times 49 (t ₁ ) and each of the turn-off periods 51 (t2) can be represented as follows: $$t_1=n\frac{1}{f_0},$$

$$t_2=m\frac{1}{f_0}.$$

In 3 is an excerpt from 2 shown. 3 shows part of the control signal 45 , part of the oscillating operating current 47 , part of one of the switch-on times 49 , part of one of the switch-off times 51 , the period 55 of the oscillating working current 47 as well as three of the several minima 59 . There is also a time interval 61 shown.

The first switching element 31 is controlled in such a way that the end of the in 3 on-time shown 49 of the first switching element 31 in the time interval 61 lies. The time interval 61 is a quarter of the period at most 55 of the oscillating working current 47 . In the time interval 61 lies a minimum 59 of the oscillating working current 47 .

As already mentioned, the statements apply to 2 at least in an analogous manner for the second, third, fourth, fifth and sixth element 33 , 35 , 37 , 39 , 41 . In particular, each of the
te 31 , 33 , 35 , 37 , 39 , 41 be controlled in such a way that the end of a corresponding switch-on period 49 each of the switching elements 31 , 33 , 35 , 37 , 39 , 41 in a corresponding time interval 61 which is at most a quarter of a period 55 of the oscillating working current 47 and in which a corresponding minimum 59 of the oscillating working current 47 lies. Likewise, each of the switching elements 31 , 33 , 35 , 37 , 39 , 41 be controlled in such a way that the corresponding switch-on time 49 each of the switching elements 31 , 33 , 35 , 37 , 39 , 41 a corresponding first multiple of the period 55 of the working current 47 by the corresponding switching element 31 , 33 , 35 , 37 , 39 , 41 is. In addition, each of the switching elements 31 , 33 , 35 , 37 , 39 , 41 be controlled in such a way that the corresponding switch-off time 51 each of the te 31 , 33 , 35 , 37 , 39 , 41 a corresponding second multiple of the period 55 of the working current 47 through the appropriate ment 31 , 33 , 35 , 37 , 39 , 41 is.

In addition, it should be noted that “having” does not exclude any other elements or steps and “a” or “an” does not exclude a plurality. It should also be pointed out that features that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features of other exemplary embodiments described above. Reference signs in the claims are not to be regarded as a restriction.

List of reference symbols

1

Power unit

3

first input port

5

second input port

7th

first output port

9

second output port

11

third output port

13

Energy storage

15th

Resonant circuit

17th

Switching unit

19th

Voltage source

21st

consumer

23

capacitor

25th

capacitor

27

Kitchen sink

29

capacitor

31

first switching element

33

second switching element

35

third switching element

37

fourth switching element

39

fifth switching element

41

sixth switching element

43

connection

45

Control signal

47

Working current through the first switching element

49

Duty cycle

51

Switch-off time

53

Period of the control signal

55

Period duration of the working current

57

Average value of the working current

59

Minimum of the working current

61

Time interval

Claims (13)

Power unit (1) with a first input connection (3) and a second input connection (5) to which an input voltage can be applied, a first output connection (7) and a second output connection (9), of which an output voltage can be provided for supplying an electrical load (21), a switching unit (17) with several switching elements (31, 33, 35, 37, 39, 41), and an oscillating circuit (15) with a coil (27) and a capacitor (29), wherein a first switching element (31) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the first input connection (3) and the first output connection (7), wherein a second switching element (33) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the second input connection (5) and the first output connection (7), a third switching element (35) of the plurality of switching elements (31, 33, 35, 37, 39, 41) being connected to the first input connection (3) and the second output connection (9), a fourth switching element (37) of the plurality of switching elements (31, 33, 35, 37, 39, 41) being connected to the second input connection (5) and the second output connection (9), wherein the resonant circuit (15) is connected to the first input connection (3) and the second input connection (5). Power unit (1) according to Claim 1 , wherein the coil (27) of the resonant circuit (15) and the capacitor (29) of the resonant circuit (15) form a parallel circuit, the coil (27) being connected to the first input connection (3) and the second input connection (5), wherein the capacitor (29) is connected to the first input connection (3) and the second input connection (5). Power unit (1) according to Claim 1 , wherein the coil (27) of the resonant circuit (15) and the capacitor (29) of the resonant circuit (15) form a series circuit, the coil (27) being connected to the first input connection (3) and the capacitor (29) to the second input terminal (5) is connected. Power unit (1) according to Claim 1 , wherein the coil (27) of the resonant circuit (15) and the capacitor (29) of the resonant circuit (15) form a series circuit, the coil (27) being connected to the second input connection (5) and the capacitor (29) to the first input terminal (3) is connected. Power unit (1) according to one of the preceding claims, wherein the power unit (1) has a third output connection (11), wherein a fifth switching element (39) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the first input connection (3) and the third output connection (11), wherein a sixth switching element (41) of the plurality of switching elements (31, 33, 35, 37, 39, 41) is connected to the second input connection (5) and the third output connection (11). Power unit (1) according to one of the preceding claims, wherein the power unit (1) has an energy store (13) which is connected to the first input connection (3) and the second input connection (5). Inverter with a power unit (1) according to one of the preceding claims and a control unit, wherein the control unit is connected to the plurality of switching elements (31, 33, 35, 37, 39, 41) of the switching unit (17) for controlling the plurality of switching elements. Method for controlling a power unit (1) according to one of the Claims 1 to 6th , wherein each of the switching elements (31, 33, 35, 37, 39, 41) is switched in such a way that each of the switching elements (31, 33, 35, 37, 39, 41) is electrically conductive during a corresponding switch-on period (49), so that an oscillating working current (47) can flow through the switching element (31, 33, 35, 37, 39, 41) and is electrically insulating during a corresponding switch-off time (51) so that the oscillating working current (47) does not pass through the switching element ( 31, 33, 35, 37, 39, 41) can flow, with at least one of the switching elements (31, 33, 35, 37, 39, 41) being controlled in such a way that the end of a corresponding switch-on period (49) of the at least one switching element (31, 33, 35, 37, 39, 41) lies in a time interval (61) which is at most a quarter of a period (55) of the oscillating working current (47) and in which a minimum (59) of the oscillating working current (47 ) is, the oscillation of the oscillating working stream (47) of de m resonant circuit (15) is caused, so that the working current (47) oscillates with the resonance frequency of the resonant circuit (15). Procedure according to Claim 8 , wherein the at least one switching element (31, 33, 35, 37, 39, 41) is controlled in such a way that the switch-on time (49) of the at least one switching element (31, 33, 35, 37, 39, 41) is a first multiple of Period duration (55) of the operating current (47) flowing through the at least one switching element (31, 33, 35, 37, 39, 41). Procedure according to Claim 8 or 9 , wherein the at least one switching element (31, 33, 35, 37, 39, 41) is controlled in such a way that the switch-off time (51) of the at least one switching element (31, 33, 35, 37, 39, 41) is a second multiple of Period duration (55) of the working current (47) which flows through the at least one switching element (31, 33, 35, 37, 39, 41) during the switch-on period (49). Method according to one of the Claims 8 to 10 , wherein each of the switching elements (31, 33, 35, 37, 39, 41) is controlled in such a way that the end of a corresponding switch-on period (49) of each of the switching elements (31, 33, 35, 37, 39, 41) in a corresponding Time interval (61) is at most a quarter of a period (55) of the oscillating working current (47) and in which a corresponding minimum (59) of the oscillating working current (47) lies. Method according to one of the Claims 8 to 11 , wherein each of the switching elements (31, 33, 35, 37, 39, 41) is controlled in such a way that the corresponding switch-on period (49) of each of the switching elements (31, 33, 35, 37, 39, 41) has a corresponding first A multiple of the period (55) of the operating current (47) flowing through the corresponding switching element (31, 33, 35, 37, 39, 41). Method according to one of the Claims 8 to 12 , wherein each of the switching elements (31, 33, 35, 37, 39, 41) is controlled in such a way that the corresponding switch-off time (51) of each of the switching elements (31, 33, 35, 37, 39, 41) is a corresponding second multiple of Period duration (55) of the working current (47) which flows through the corresponding switching element (31, 33, 35, 37, 39, 41) during the corresponding switch-on period.

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