Voltage conversion assembly, electric drive system and method for operating voltage conversion assembly

Abstract

The invention relates to a voltage conversion assembly in an electric drive system, which voltage conversion assembly can actuate a coupled electric machine in one operating mode and can convert an input DC voltage into an output DC voltage in the other operating mode. In order to convert an input DC voltage into an output DC voltage, a phase winding of the connected electric machine can be used as an inductor. In this case, the individual phase windings can be individually energized as a function of the rotor position and a target value specification of the total current.

Description

Technical Field

[0001] The present invention relates to a voltage conversion component, an electric drive system and a method for operating a voltage conversion component. In particular, the present invention relates to voltage conversion when using a component of an electric drive system. Background Art

[0002] Vehicles that are fully or at least partially electrically driven usually have an electric drive system, in which electrical energy is supplied to the electric machine from an energy storage device, such as a traction battery, by means of an inverter. The electrical energy storage device used for this purpose can be charged by means of an external energy source. For this purpose, a separate charging circuit is usually required.

[0003] In addition, there is the possibility of using components of the electric drive system for charging the electric energy storage device. Such an arrangement is described, for example, in the publication DE 10 2018 207 188 A1. Summary of the invention

[0004] The invention provides a voltage conversion assembly, an electric drive system and a method for operating a voltage conversion assembly having the features of the independent claims. Further advantageous embodiments are the subject matter of the dependent claims.

[0005] Therefore, it is proposed that:

[0006] A voltage conversion assembly having a voltage conversion circuit and a control device. The voltage conversion circuit is configured to be connected to a multi-phase motor. In addition, the voltage conversion circuit is configured to convert an input DC voltage provided at the voltage conversion circuit into a predetermined output DC voltage in a first operating mode when the motor is stopped. The control device is configured to regulate a current flowing through at least one phase winding of the multi-phase motor connected to the voltage conversion circuit during the conversion of the input DC voltage into the predetermined output DC voltage. In this case, the current flowing through the corresponding phase winding is regulated in particular by using the rotor position of the motor.

[0007] In addition, it is proposed that:

[0008] An electric drive system having a voltage conversion assembly according to the invention and a multi-phase electric machine, wherein the electric machine is electrically coupled to the voltage conversion assembly.

[0009] Finally proposed:

[0010] Method for operating a voltage conversion component. The voltage conversion component comprises a voltage conversion circuit. The voltage conversion circuit is configured to be connected to a multi-phase motor. The method comprises a step for acquiring a rotor position of the motor connected to the voltage conversion circuit. In addition, the method comprises a step for controlling the voltage conversion circuit to convert an input DC voltage provided at the voltage conversion circuit into a predetermined output DC voltage. In particular, the input DC voltage is converted into an output DC voltage when the connected motor is stopped. Here, by the method according to the invention, the current flowing through at least one phase winding of the multi-phase motor connected to the voltage conversion circuit is separately adjusted during the conversion of the input DC voltage into the predetermined output DC voltage. In particular, the current is adjusted by using the acquired rotor position of the motor.

[0011] Advantages of the present invention.

[0012] The invention is based on the finding that the resulting inductance of the individual phase windings of a multiphase electric machine can vary depending on the rotor position of the electric machine, in particular a permanent-magnet synchronous machine. If components of an electric drive system are used for voltage conversion of an input DC voltage into an output DC voltage, the electrical characteristics caused by the inductance or the position-dependent inductance can therefore also fluctuate.

[0013] The idea of ​​the present invention is therefore to take this knowledge into account and to take into account the rotor position and the resulting changing inductance of the phase windings in the electric machine when using components of the electric drive system for voltage conversion.

[0014] In this regard, it is proposed that when components of the electric drive system are used for voltage conversion from an input DC voltage to an output DC voltage, the current flowing through the phase windings, i.e. the stator windings, of the connected electric machine is adapted separately. In other words, a plurality of phase windings in the connected electric machine is used for voltage conversion, and the current flowing through the phase windings used can then be adapted individually. In this case, the respective current flowing through the individual phase windings can be adjusted, in particular taking into account the current rotor position or the respective inductance of the phase windings caused thereby, and the required total current intensity.

[0015] In this way, the overall system for the voltage conversion of the input DC voltage into the output DC voltage can be adapted to the respectively resulting inductance of the connected electric machine. In this way, the operating characteristics for the voltage conversion can be optimized.

[0016] In particular, by taking into account the rotor position and the inductance caused thereby for the current supply of the phase windings, the resulting current ripple and / or voltage ripple can be minimized. The need for filtering measures or interference suppression measures is thereby also reduced. In particular, for example, the capacitance required for compensating the mentioned current regulators and / or voltage regulators can be minimized. Furthermore, by the individual current supply of the phase windings according to the invention as a function of the rotor position, the torque occurring in the electric machine during the voltage conversion can also be minimized.

[0017] According to one embodiment, the voltage conversion circuit includes a DC voltage connection and an AC voltage connection. The DC voltage connection is configured to be connected to an energy storage device, such as a battery. The AC voltage connection is configured to be connected to a motor. In addition, the voltage conversion circuit can be configured to receive an input DC voltage between a connection point of the DC voltage connection and a motor connection in a first operating mode, and to provide an output DC voltage between a first connection point and a second connection point of the DC voltage connection. Therefore, the voltage conversion circuit is, for example, a converter configured to control the motor by using the electrical energy provided by the energy storage device at the DC voltage connection. Additionally or alternatively, such a converter can charge the energy storage device using the electrical energy provided by the motor in the form of an AC voltage. Such a circuit rule can be used in another operating mode, which is referred to here as the first operating mode, in order to convert a DC voltage provided by an external DC voltage source into a DC voltage suitable for charging the energy storage device. For this purpose, the energy storage device is connected to the DC voltage connection unchanged. The input DC voltage can be provided between the connection point (preferably the negative pole) of the energy storage device and the motor connection. Depending on the design, the phase connections of the electric machine or the star point of the electric machine can be used as motor connections. In other words, the input DC voltage of the external energy source is provided between the phase connections or the star point of the electric machine and the connection points of the electric energy storage device or the connection points of the DC voltage connection of the voltage conversion circuit.

[0018] According to one embodiment, the control device of the voltage conversion component is configured to adjust one or more currents flowing through at least one of the phase windings by using a target value of the total current to be adjusted. The total current here refers to, for example, the current at the input or output of the voltage conversion component. Correspondingly, the total current to be adjusted can be distributed to one or more of the phase windings according to the rotor position. For example, it can be provided that at relatively low total currents, the current is completely distributed to one phase winding. On the contrary, for higher currents, it may be necessary to distribute the total current to two or more phase windings. In this distribution, in particular, the rotor position or the inductance generated by the rotor position for each phase winding can also be taken into account.

[0019] According to one specific embodiment, the control device of the voltage conversion assembly is designed to determine the inductance values ​​for the phase windings of the multi-phase electric machine connected to the voltage conversion circuit. In particular, the individual inductances of the respective phase windings are determined by using the rotor position of the electric machine. In addition, the control device is designed to regulate the current flowing through the phase windings of the electric machine by using the determined inductance values. By determining the induced inductance values ​​of the phase windings of the connected electric machine, a variable which is very suitable for determining the current flowing through the respective phase winding is thus provided.

[0020] According to one embodiment, the voltage conversion component includes a storage device. The storage device is configured to provide data for the relationship between the rotor position of the motor and the current to be adjusted in the phase winding of the motor. In this case, the control device is configured to read the data stored in the storage device and adjust the current flowing through each phase winding of the connected motor by using the data read from the storage device. The relationship between the rotor position and the corresponding current to be adjusted can be stored, for example, in a so-called lookup table or in any other form. In addition to the tabular form, in particular, a relationship between the rotor position and the current to be adjusted can also be provided in the form of a formula. In addition, more complex relationships are also feasible, in which, in addition to the rotor position and the current to be adjusted, other parameters are also taken into account. These other parameters can include, for example: input current, output current, input voltage, output voltage or any other operating parameter, such as, for example, temperature, in particular rotor temperature and / or stator temperature.

[0021] According to one specific embodiment, the control device is designed to adjust the phase offset between the currents flowing through at least two phase windings of a multiphase electric machine connected to the voltage conversion circuit. The adjustment can be performed by using the rotor position of the electric machine and the required charging current intensity if necessary. In particular, the phase offset between the AC voltages used to load the individual rotor phases can be adapted as a function of the rotor position and / or the respective inductances caused by the individual phase windings. For example, even in the case of pulse width modulated control for loading the individual phase windings with current, the rising or falling edges of the individual pulses or the pulse center can be adapted as a function of the rotor position.

[0022] According to one embodiment, the control device of the voltage conversion assembly is configured to receive a signal from a rotor angle sensor of the motor. In this case, the current flowing through the phase winding of the motor can be adjusted by using the signal received from the rotor angle sensor. In other words, the corresponding rotor position is obtained by receiving a corresponding sensor signal from a rotor angle sensor coupled to the motor.

[0023] According to another embodiment, the control device of the voltage conversion assembly is configured to calculate or estimate the rotor position of a multiphase motor connected to the voltage conversion circuit. Correspondingly, the current flowing through the phase winding of the motor is regulated by using the rotor position thus obtained. In this case, the rotor position of the connected motor can be calculated or estimated based on a mathematical model or the like.

[0024] According to one specific embodiment, the control device of the voltage conversion assembly is designed to regulate the current flowing through the phase windings of the motor by using further operating parameters of the voltage conversion assembly and / or of the multiphase motor connected to the voltage conversion circuit. In this way, an optimized operating point can be obtained, which, in addition to the rotor position of the connected motor and the respective inductances in the phase windings caused thereby, also takes into account other operating parameters for optimized operation. These other operating parameters can include, for example: voltage levels / current levels of the input voltage and / or output voltage, operating temperature, in particular calculated, estimated or measured temperatures in or at the connected motor, in particular at the stator and / or rotor of the motor, and any other suitable operating parameters.

[0025] According to one embodiment, the voltage conversion component is further configured to provide a voltage for controlling a multiphase motor in a second operating mode. In other words, the voltage conversion component according to the invention is suitable for controlling a connected motor on the one hand. In addition, the voltage conversion component is also suitable for using the inductance of the phase winding of the connected motor for voltage conversion from an input DC voltage to an output DC voltage. Thus, for example, an electric drive system can be realized, which obtains electrical energy from a connected electrical energy storage device for operating the motor. In this case, the electrical energy storage device can be charged by using components of the control circuit of the motor and the inductance of the phase winding of the connected motor. As a result, multiple utilization of existing components can be achieved.

[0026] As long as it makes sense, the above-mentioned construction schemes and modifications can be combined with each other arbitrarily. Other construction schemes, modifications and implementation schemes of the present invention also include combinations of features not explicitly mentioned in the previous or following descriptions of the embodiments of the present invention. In particular, those skilled in the art can also add various aspects as improvements or supplements to the corresponding basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features and advantages of the present invention are explained below with reference to the accompanying drawings.

[0028] Figure 1 A schematic diagram of a circuit arrangement for an electric drive system is shown, which can serve as a basis for an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of an alternative circuit arrangement for an electric drive system is shown, which can serve as a basis for an embodiment of the present invention;

[0030] Figure 3 A schematic diagram showing a block diagram of an electric drive system having a voltage conversion component according to one embodiment;

[0031] Figure 4 A flow chart is shown which is the basis for a method for operating a voltage conversion component according to one specific embodiment. DETAILED DESCRIPTION

[0032] Figure 1 A schematic diagram of a circuit arrangement structure for an electric drive system is shown. The electric drive system includes a voltage conversion circuit 10. The voltage conversion circuit 10 can be electrically coupled to an energy storage device 3, such as a battery, at a DC voltage connection. For this purpose, the DC voltage connection can, for example, have two connection points, and the two electrodes of the energy storage device 3 can be connected to these two connection points. In addition, the voltage conversion circuit 10 can be electrically coupled to the motor 2 at an AC voltage connection. The motor 2 can, for example, be a multi-phase motor having, for example, three phase windings W1, W2, and W3. Correspondingly, the AC voltage connection can have a connection point for each phase winding W1, W2, and W3. However, the present invention is not limited to three-phase motors. More precisely, in principle, any other multi-phase motor having a phase winding different from three can be used.

[0033] To operate the electric drive system, the voltage converter circuit 10 can convert the voltage provided by the energy storage device 3 into a multiphase AC voltage according to a target value specification and provide it to the motor 2. To this end, the switching elements S1-S6 of the voltage converter circuit 10 are correspondingly controlled.

[0034] In another operating mode, the voltage conversion circuit 10 together with the connected electric machine 2 can be used to convert the voltage of the external energy source 4 into a voltage suitable for charging the electric energy storage device 3. In this case, the phase windings W1, W2, W3 can be used as inductive components. For this purpose, the electric energy provided by the external energy source 4 can be provided, in particular in the form of a DC voltage, between the motor connection and the connection point of the electric energy storage device 3. Preferably, for this purpose, any switches that are present between the external energy source 4 and the motor connection and the connection point of the electric energy storage device 3, preferably the negative connection point or the negative pole of the electric energy storage device 3, are closed. As will be discussed in detail below, the motor connection is in particular a connection at one of the phase windings or a connection at the star point of the phase windings.

[0035] exist Figure 1In the embodiment shown in , for this purpose, for example, the connection of the external energy source 4 is electrically coupled to the star point S of the electric machine 2. Such a circuit arrangement is also referred to as a W connection. The phase windings W1, W2, W3 can be energized by suitable clocking of the switching elements M1-M6 of the voltage conversion circuit 10. In this way, the voltage level and / or the current intensity from the external energy source 4 for charging the electrical energy storage 3 can be adapted.

[0036] Figure 2 1 shows a schematic diagram of another circuit arrangement of an electric drive system, in which a voltage conversion circuit 10 and an electric machine 2 can also be used, which convert the voltage provided by an external energy source 4 into a voltage suitable for charging an electrical energy storage device 3. Figure 2 The circuit arrangement of differs from the previously described circuit arrangement in particular in that here it is not the star point S of the electric machine 2 that is connected to the connection of the external energy source 4, but rather the connection of the phase winding W3. This circuit arrangement is referred to as a Y connection. Preferably, for this purpose, any switches present between the external energy source 4 and the motor connection and the connection point of the electric energy store 3, preferably the negative connection point or the negative pole of the electric energy store 3, are closed.

[0037] Figure 3 1 shows a schematic diagram of a block diagram for an electric drive system according to an embodiment. The electric drive system can include a voltage conversion component 1, which is electrically connected to the motor 2. The voltage conversion component 1 can include a voltage conversion circuit 10, which converts a voltage provided by the electric energy storage device 3, in particular a DC voltage, into a voltage suitable for driving the motor 2. In this case, it can be related in particular to the above-mentioned Figure 1 and Figure 2 The voltage conversion circuit 10 described. Correspondingly, the voltage conversion component 1 having the voltage conversion circuit 10 can also convert the electrical energy from the external energy source 4 into a voltage suitable for charging the electrical energy storage 3 in another operating mode. For this purpose, the voltage conversion circuit 10 and in particular the switching elements M1-M6 of the voltage conversion circuit 10 can be controlled by the control device 20 through corresponding control signals. In addition, Figure 1 and Figure 2 Switching elements (not described in detail) between the external energy source 4 , the voltage conversion circuit 10 and the electrical energy store 3 can also be switched off or on in a suitable manner depending on the operating mode.

[0038] In an operating mode for converting an input DC voltage from an external energy source 4 into a voltage for charging the electrical energy storage device 3, the phase windings W1, W2, W3 are used as inductive components in the electric machine 2. In this case, the inductance caused by the respective phase windings W1, W2, W3 of the electric machine 2 can vary depending on the position of the rotor and the desired total current flowing through the phase windings W1, W2, W3 of the electric machine 2. Therefore, the control device 20 of the voltage conversion component 1 adapts the control of the voltage conversion circuit 10 depending on the rotor position of the electric machine 2 or the inductance caused thereby of the phase windings W1, W2, W3. As a result, a separate current is realized for each phase winding W1, W2, W3 used depending on the rotor position of the electric machine 2.

[0039] For this purpose, the current rotor position of the rotor of the electric machine 2 can be detected, for example, by means of a rotor position sensor 2a or a resolver, and provided to the control device 20. Alternatively, any other method can also be used to acquire the rotor position. The rotor position can also be determined or estimated, for example, by means of a sensorless method.

[0040] In order to control the voltage conversion circuit 10, the relationship between the rotor position and the parameters for controlling the voltage conversion circuit 10 can be stored in the control device 20, for example. For this purpose, for example, a storage device 21 can be provided in the control device 20, which stores and provides the previously acquired relationship between the rotor position and the control parameters. These relationships can be provided in the form of a table, such as a so-called lookup table, etc. In addition, of course, there can also be any other feasible way to display the relationship between the rotor position and the control of the voltage of the circuit 10. In particular, for example, the relationship can also be displayed by means of a formula relationship, a mathematical model, etc.

[0041] In addition to the current rotor position, other suitable parameters can also be taken into account for adapting the control of the voltage converter circuit 10. For example, the control can also be adapted as a function of the input voltage, input current, output voltage, output current or other operating parameters such as temperature, for example motor temperature, in particular the temperature in the phase winding or rotor of the electric machine 2.

[0042] By adapting the control of the respective energization of the phase windings W1, W2, W3, it is possible to adapt not only the current level in the individual phase windings W1, W2, W3, but also the phase shift between the voltages applied to the individual phase windings W1, W2, W3. In addition, the number of phase windings W1, W2, W3 used for converting the input DC voltage into the output DC voltage can also be changed according to requirements, for example, according to the rotor position, the desired charging current, the voltage level, etc. For example, only a part of the available phase windings W1, W2, W3 can be energized as necessary depending on the operating point.

[0043] The individual current supply of the individual phase windings W1, W2, W3 can be regulated first at the beginning of the voltage conversion by using the rotor position and, if necessary, other parameters. In addition, the current supply of the individual phase windings W1, W2 or W3 can also be dynamically adapted during operation, i.e., during the voltage conversion. In this way, the time-varying characteristics of the system can be taken into account if necessary. If, for example, the output DC voltage is used to charge the electrical energy storage device 3, the output DC voltage can rise during the charging period. This may cause the parameters required for the individual current supply of the phase windings W1, W2, W3 to change over time. For this purpose, any operating parameters of the voltage conversion component 1 and, if necessary, other components of the overall system, such as the motor 2, can be monitored, such as, for example, detected in a measurement technology manner or determined in another way, such as with the help of a mathematical model, and the corresponding optimized parameters for the current supply of the individual phase windings W1, W2, W3 can be obtained and adjusted.

[0044] Figure 4 A flow chart is shown, which is the basis for a method for operating a voltage conversion component 1 according to an embodiment. The voltage conversion component 1 is, for example, the voltage conversion component 1 described previously. Correspondingly, all previously made embodiments also apply to the method described below. In addition, the previously described voltage conversion component 1 can also include any components suitable for implementing the method described below.

[0045] In step 110, the rotor position of the motor 2 connected to the voltage conversion circuit 10 is first acquired. Subsequently, in step 120, the voltage conversion circuit 10 is controlled to convert the input DC voltage provided at the voltage conversion circuit 10 into a predetermined output DC voltage. In this case, the voltage is converted, in particular, when the connected motor 2 is stopped.

[0046] During the conversion of the input DC voltage into a predetermined output DC voltage, as described above, the current flowing through at least one phase winding W1 , W2 , W3 of the multiphase motor 2 coupled to the voltage conversion circuit 10 is regulated by using the detected rotor position of the motor 2 .

[0047] In summary, the present invention relates to a voltage conversion component in an electric drive system, which can control a connected electric machine in one operating mode and can convert an input DC voltage into an output DC voltage in another operating mode. In order to convert the input DC voltage into the output DC voltage, the phase windings of the connected electric machine can be used as inductors. In this case, the individual phase windings are energized separately according to the rotor position and the target value preset of the total current.

Claims

1. A voltage conversion component (1), comprising: A voltage conversion circuit (10) configured to be connected to a multi-phase motor (2) and to convert an input DC voltage provided at the voltage conversion circuit (10) into a predetermined output DC voltage in a first operating mode when the motor (2) is stopped; and A control device (20) is configured to regulate a current flowing through at least one phase winding (W1, W2, W3) of a multi-phase motor (2) coupled to the voltage conversion circuit (10) by using a rotor position of the motor (2) during conversion of an input DC voltage to a predetermined output DC voltage.

2. The voltage conversion component (1) according to claim 1, wherein: The voltage conversion circuit (10) comprises a DC voltage connector and an AC voltage connector, wherein the DC voltage connection is designed for connection to an electrical energy storage device (3), and the AC voltage connection is designed for connection to the electric machine (2), and The voltage conversion circuit (10) is configured to receive an input DC voltage between a connection point of the DC voltage connection and a motor connection on the input side in the first operating mode and to provide an output DC voltage between a first connection point and a second connection point of the DC voltage connection on the output side.

3. The voltage conversion component (1) according to claim 1 or 2, wherein: The control device (20) is designed to regulate a current flowing through at least one phase winding (W1, W2, W3) of a multi-phase electric machine (2) coupled to the voltage conversion circuit (10) by using a target value of a total current to be regulated.

4. The voltage conversion component (1) according to any one of claims 1 to 3, wherein: The control device (20) is configured to respectively determine the inductance values ​​of the phase windings (W1, W2, W3) of the multi-phase motor (2) connected to the voltage conversion circuit (10) by using the rotor position of the motor (2), and to adjust the current flowing through the phase windings (W1, W2, W3) of the motor (2) by using the acquired inductance values.

5. The voltage conversion component (1) according to any one of claims 1 to 4, comprising a storage device (21) which is designed to provide data for the relationship between the rotor position of the motor (2) and the current to be regulated in the phase windings (W1, W2, W3) of the motor (2), in, The control device (20) is designed to read out data stored in the storage device (21) and to regulate the current by using the data read out from the storage device (21).

6. The voltage conversion component (1) according to any one of claims 1 to 5, wherein: The control device (20) is designed to adjust a phase shift between currents flowing through at least two phase windings (W1, W2, W3) of a multi-phase electric machine (2) coupled to the voltage conversion circuit (10) by using a rotor position of the electric machine (2).

7. The voltage conversion component (1) according to any one of claims 1 to 6, wherein: The control device (20) is configured to receive a signal from a rotor angle sensor (2a) of the motor (2) and to regulate a current flowing through a phase winding (W1, W2, W3) of the motor (2) by using the signal received from the rotor angle sensor (2a).

8. The voltage conversion component (1) according to any one of claims 1 to 7, wherein: The control device (20) is designed to calculate the rotor position of a multi-phase motor (2) connected to the voltage conversion circuit (1) and to regulate the current flowing through the phase windings (W1, W2, W3) of the motor (2) by using the calculated rotor position.

9. The voltage conversion component (1) according to any one of claims 1 to 8, wherein: The control device (20) is designed to regulate the current flowing through the phase windings (W1, W2, W3) of the motor (2) by using further operating parameters of the voltage conversion component (1) and / or of a multi-phase motor (2) coupled to the voltage conversion circuit (10).

10. The voltage conversion component (1) according to any one of claims 1 to 9, wherein: The voltage conversion component (1) is further designed to provide an AC voltage in a second operating mode in order to actuate the multi-phase electric machine (2).

11. An electric drive system having: The voltage conversion assembly (1) according to any one of claims 1 to 10; and A multi-phase motor (2) is electrically coupled to the voltage conversion component (1).

12. A method for operating a voltage conversion component (1) having a voltage conversion circuit (10) which is designed to be connected to a multi-phase electric machine (2), the method comprising the following steps: Acquiring (110) a rotor position of a motor (2) connected to the voltage conversion circuit (10); controlling (120) the voltage conversion circuit (10) to convert an input DC voltage provided at the voltage conversion circuit (10) into a predetermined output DC voltage when the connected motor (2) stops, in, During the conversion of the input DC voltage to the predetermined output DC voltage, the current flowing through at least one phase winding (W1, W2, W3) of a multi-phase motor (2) coupled to the voltage conversion circuit (10) is regulated by using the acquired rotor position of the motor (2).

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