DE102021111590A1 - Method for operating an electric drive unit of a motor vehicle in different operating modes, control device, drive unit and motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an electric drive unit (1) of a motor vehicle in different operating modes, wherein - to provide an operating mode with optimal power loss, output voltages (uu, uv, uw) of an inverter (3) of the drive unit (1) are modulated in such a way that output currents (iu, iv, iw) of the inverter (3) for an electric machine (2) of the drive unit (1) have a first harmonic content (H1), and for providing an operating mode that increases power loss for heating at least one component (4) of the motor vehicle the output voltages (uu, uv, uw) are modulated in such a way that the output currents (i*u, i*v, i*w) have a second harmonic content (H2) that is greater than the first harmonic content (H1), with a specific Operating point of the electrical machine (2) by means of a pulse method in each case corresponding to the power loss-optimal operating mode a first pulse pattern and a second pulse pattern corresponding to the operating mode that increases power loss are generated, by which the same short-term average values of the output voltages (uu, uv, uw) are modulated, so that the drive unit (1) transfers from one operating mode to the other operating mode without changing the operating point becomes.

Description

The invention relates to a method for operating an electric drive unit of a motor vehicle in different operating modes. In order to provide an operating mode with optimal power loss, output voltages of an inverter of the drive unit are modulated in such a way that output currents of the inverter for an electric machine of the drive unit have a first harmonic content. To provide an operating mode that increases power loss for heating at least one component of the motor vehicle, the output voltages are modulated in such a way that the output currents have a second harmonic content that is greater than the first harmonic content. The invention also relates to a control device, an electric drive unit and a motor vehicle.

In the present case, interest is directed towards electrically drivable motor vehicles which have an electric drive unit with an electric machine, an inverter and at least one component to be heated. The electric machine provides an operating point-specific torque or drive torque for the motor vehicle. For this purpose, by appropriate control of the inverter, output voltages or phase voltages are modulated, which generate output currents for energizing phases of the electrical machine, which in turn generate a torque-specific rotating field in a stator of the electrical machine. It is known from the prior art to operate the electric drive unit in different operating modes, through which a power loss of the electric drive unit can be changed. In an operating mode that is optimal in terms of power loss, the electric drive unit is operated in such a way that the power loss is minimal. In an operating mode that increases power loss, the electric drive unit is operated in such a way that the power loss is increased and can be used to heat the at least one component. To this the DE 10 2016 211 762 A1 for example, in order to increase the power loss, to superimpose a fundamental wave of the generated output current with parasitic harmonics. For this purpose, a switching frequency and thus a switching frequency of switches of the inverter are reduced or a control method of the inverter is changed.

It is the object of the present invention to provide an alternative method to the prior art for increasing a power loss used for heating in an inefficient operating mode of an electric drive unit.

According to the invention, this object is achieved by a method, a control device, an electric drive unit and a motor vehicle having the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject matter of the dependent patent claims, the description and the figures.

A method according to the invention serves to operate an electric drive unit of a motor vehicle in different operating modes. In order to provide an operating mode with optimal power loss, output voltages of an inverter of the drive unit are modulated in such a way that operating point-specific output currents of the inverter for an electric machine of the drive unit have a first harmonic content. To provide an operating mode that increases power loss for heating at least one component of the motor vehicle, the output voltages are modulated in such a way that the operating-point-specific output currents have a second harmonic content that is greater than the first harmonic content. According to the invention, a first pulse pattern corresponding to the power loss-optimal operating mode and a second pulse pattern corresponding to the power loss-increasing operating mode are generated for each operating point of the electrical machine by means of a pulse method, by which the same short-term average values of the output voltages are modulated, so that the drive unit changes from one operating mode to the other Operating mode is transferred without changing the operating point.

The invention also includes a control device for an electric drive unit of a motor vehicle, which is designed to carry out a method according to the invention, and an electric drive unit for a motor vehicle, which has an electric machine for providing a torque, power electronics connected to the electric machine, in particular a Inverter, a control device according to the invention and at least one component to be heated. The electric machine serves as a traction machine for the motor vehicle and provides a drive torque. The at least one component to be heated is preferably an electrical energy store of the motor vehicle. The electrical energy store can be a high-voltage energy store and act as a traction battery for providing electrical energy for the electric machine. The elec ric machine and the electrical energy storage device are electrically connected via the inverter.

The drive unit also has, in particular, a cooling circuit that carries coolant, to which the electric machine, the power electronics and the at least one component of the motor vehicle to be heated can be connected, with the control device being designed to provide the power loss-increasing, inefficient operating mode for the drive unit if the at least one component to be heated provides a heating request signal. In the inefficient operating mode, the power loss emitted by the electric drive unit in the form of heat can be transported via the coolant of the cooling circuit to the at least one component to be heated. The electric drive unit can therefore emit the heat loss deliberately “generated” in the inefficient operating mode to the coolant, which transports the heat loss to the at least one component to be heated.

The electrical machine has a stator and a rotor which is mounted such that it can rotate with respect to the stator. The electrical machine can be, for example, an externally excited synchronous machine (SSM) in which the rotor has rotor windings that can be energized, or a permanently excited synchronous machine (PSM) in which the rotor has permanent magnets. The electrical machine can also be designed as an asynchronous machine. The stator has stator windings or phase windings, which can be connected, for example, to form three phase strands or winding strands u, v, w. To provide a specific working point, which is characterized by a predetermined torque requested by a driver of the motor vehicle and by a predetermined speed, phase-shifted electrical phase currents are fed to these winding strands to generate a rotating field specific to the working point. To do this, the inverter applies output voltages to the phase strands as target phase voltages. The phase currents are output currents of the inverter connected to the phases of the stator. The rotating magnetic field causes the rotor to rotate in order to provide the operating point-specific torque.

A pulse method, in particular pulse width modulation, is used to generate or modulate the output voltages. Pulse patterns are generated by means of this pulse method, based on which switches of the inverter designed as a pulse-controlled inverter are switched by the control device. The pulsed output voltages provided at the output of the inverter result in almost sinusoidal output currents due to the phase windings of the electrical machine. In the power loss-optimized, efficient operating mode, the first pulse patterns for providing the setpoint values are determined in such a way that the power loss of the electric machine is minimal. Since the power loss depends, among other things, on a ripple in the rotary field, which in turn depends on a ripple in the output currents, these ripples are minimized in order to provide the efficient operating mode. This means that the output voltages are modulated in such a way that the fundamental waves of the output currents, which generate the usable torque, are superimposed with as few harmonics as possible. In addition, the amplitude of the fundamental wave is adjusted in particular in such a way that the losses of the drive unit are minimized. Output voltages are thus modulated by means of the first pulse pattern, as a result of which the associated output currents have the first, minimum harmonic content.

In order to convert the electrical machine into the inefficient operating mode, the second pulse pattern is determined in such a way that the harmonic content of the output currents is increased. The second harmonic content for increasing the heat loss is preferably always generated when the at least one component of the motor vehicle to be heated provides the heating request signal. The drive unit is therefore only switched to the inefficient operating mode when the at least one component to be heated has to be heated. In addition to copper losses, the increase in the harmonic content increases iron losses or core losses in the machine.

In order to provide the different operating modes, two pulse patterns are provided for each operating point. The first, minimum harmonic content is generated by means of the first pulse pattern, and the second, higher harmonic content is generated by means of the second pulse pattern. Depending on the operating mode to be provided, the first or the second pulse pattern is therefore selected for each operating point. Both pulse patterns generate the same short-term mean value of the output voltage, so that the same current fundamentals are generated for both pulse patterns. The short-term average is the average of the output voltage over a switching period. In addition, the two pulse patterns corresponding to an operating point are generated using the same pulse method. There is therefore no change in the pulse method when changing the operating modes. Also, the switching frequency of the inverter switches in particular not changed when changing the operating modes. Only a signal form of the activation of the switches, which is predetermined by the pulse pattern, is changed.

In a first embodiment, the pulse patterns are generated by means of a pulse method in the form of space vector modulation. The first pulse patterns are generated by means of a basic voltage vector and a zero voltage space vector. In the respective second pulse patterns corresponding to the same operating point, at least part of the zero voltage space vector of the associated first pulse pattern is replaced by at least two basic voltage space vectors of different signs. A time duration and/or a proportion of the basic voltage space vectors of different signs is preferably specified for setting a level of the power loss. In space vector modulation, basic voltage space vectors or active voltage vectors and zero voltage space vectors or passive voltage vectors are used to generate an output voltage which is represented by a voltage space vector with a specific phase angle and a specific amplitude. In the case of a 2-level inverter, six basic voltage vectors and two zero voltage vectors are used to generate the output voltages. In the case of a 3-level inverter, 18 basic voltage vectors and three zero voltage vectors are used to generate the output voltages. In this case, a first, operating-point-specific sequence of basic voltage space vectors and zero-voltage space vectors is specified for a specific operating point in order to provide a first pulse pattern.

To provide the second pulse pattern that corresponds to this operating point, a second sequence is provided, which differs from the first sequence in terms of its proportion of zero-voltage space vectors. To generate the second sequence, at least part of the zero voltage space vector of the first sequence is replaced by at least two active voltage vectors with opposite voltages, ie opposite signs. The duration and the direction of the new voltage vectors are selected in such a way that the geometric addition of these voltage vectors results in zero. This ensures at all times that the short-term mean value of the voltage at the electrical machine and thus its operating point remain unchanged. The additional power loss can be linearly adjusted and thus regulated by a size of the proportion of the replacement of the zero vectors and/or a period of time.

In a second embodiment, the pulse patterns are generated using a pulse method based on offline-optimized pulse patterns. In particular, first switching angles for switches of the inverter are determined for the first pulse pattern, which are optimized with regard to a first, in particular minimum, harmonic, and second switching angles are determined for the respective second pulse patterns corresponding to the same operating point, which are optimized with regard to a second, in particular maximum, harmonic are optimized. These offline-optimized pulse patterns are predetermined depending on the working point to be provided and stored in tables, for example. In this case, two or more tables with pulse patterns which are optimized for different harmonic content can be stored in the control device. One of these tables contains the first pulse patterns, which are optimized for the lowest, first harmonic content and which are used for the power loss-optimal, efficient operating mode. At least one further table contains the second pulse patterns, which are optimized for the second, maximum or maximum desired harmonic content and which are used for the power loss-increasing, inefficient operating mode. In this case, a table with a respective second pulse pattern can be specified for each desired harmonic content that generates a certain desired power loss. Depending on the desired level of power loss, the table with the corresponding second pulse pattern can then be selected.

However, it can also be provided that, in order to set the level of the power loss, a pulse sequence control is carried out from at least one first pulse pattern and at least one second pulse pattern, with a time ratio of the at least one first pulse pattern and the at least one second pulse pattern depending on the level of the power loss is determined. It is therefore switched back and forth between the first and the second pulse pattern for a respective operating point to provide the inefficient operating mode, so that the level of the power loss can be set via a duty cycle, depending on the required heating power.

The invention also includes a motor vehicle with a drive unit according to the invention. The motor vehicle is in particular an electric or hybrid vehicle and has the electric machine as a traction machine.

The embodiments presented with reference to the method according to the invention and their advantages apply correspondingly to the control device according to the invention, the drive unit according to the invention and to the motor vehicle according to the invention.

Further features of the invention result from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own.

• 1 eine schematische Darstellung einer Ausführungsform einer elektrischen Antriebseinheit;
• 2 eine schematische Darstellung von Ausgangsströmen mit jeweils unterschiedlichem Oberwellengehalt,
• 3 eine Darstellung eines Raumzeigerdiagramms;
• 4 eine Darstellung zweier offline-optimierter Pulsmuster mit unterschiedlichen Schaltwinkeln.

The invention will now be explained in more detail using a preferred exemplary embodiment and with reference to the drawings. Show it:

• 1 a schematic representation of an embodiment of an electric drive unit;
• 2 a schematic representation of output currents with different harmonic content,
• 3 a representation of a space vector diagram;
• 4 a representation of two offline-optimized pulse patterns with different switching angles.

Elements that are the same or have the same function are provided with the same reference symbols in the figures.

1 shows an electric drive unit 1 with an electric machine 2, an inverter 3 and at least one component 4 to be heated. The component 4 to be heated is here an electrical energy store in the form of a high-voltage energy store. However, the component 4 to be heated can also be a passenger compartment of the motor vehicle. The component 4 to be heated and the electric machine 2 are thermally coupled via a coolant-carrying cooling circuit 6, which is only indicated schematically here. The inverter 3 is controlled by a control device 7 of the electric drive unit 1 in order to operate the electric machine 2 in different operating modes.

The electrical machine 2 can be operated in an efficient operating mode that is optimal in terms of power loss, in which the electrical machine 2 emits minimal power loss and thus heat loss. The efficient operating mode is always provided when the component 4 to be heated has no heating requirement. The electrical machine 2 can also be operated in an inefficient operating mode that increases the power loss, in which the electrical machine 2 emits a higher power loss or heat loss compared to the efficient operating mode. The inefficient operating mode is provided whenever component 4 has a heating requirement. The heat loss provided by the electrical machine 2 is then supplied to the component 4 via the coolant of the cooling circuit 6 . The inverter funnel 3 can also be integrated into the cooling circuit 6 so that heat loss from the inverter 3 can also be transported to the component 4 to be heated.

The inverter 3 is connected to three phase windings u, v, w of a stator of the electrical machine 2 . In order to be able to provide a required, operating point-specific torque M, the inverter 3 is controlled by the control device 7 for modulating output voltages or target phase voltages u _u , u _v , u _w , which are applied to the three phase windings u, v, w of the electrical Machine 2 are created and through which the phase windings u, _v , w are energized with output currents or phase currents i _u , iv, i _w . These phase currents i _u , _iv , i _w generate a rotating field which causes a rotor of the electrical machine 2 to rotate in order to provide the torque M specific to the operating point.

A level of the power loss is also dependent on a harmonic content of the output currents i _u , _iv , i _w , i* _u , i* _v , i* _w . Such harmonics or harmonics, which are superimposed on a respective fundamental wave of the output currents i _u , i _v , i _w , generate copper losses and iron losses and thus increased heat loss. In the efficient operating mode, the output voltages _uu , uv, uw are modulated in such a way that the harmonic content of the associated output _{currents iu, iv, iw, i*u, i*v , i * w is as low} as possible. In the inefficient operating mode, the control of the inverter 3 is changed in such a way that additional higher frequency components and thus a higher harmonic content of the output currents i _u , i _v , i _w , i* _u , i* _v , i* _w arise. The control is designed in such a way that the short-term average value of the control remains unchanged in the inefficient operating mode compared to the efficient operating mode. This boundary condition means that the operating point of the electrical machine 2, which leads to the generation of the desired drive torque M, remains unchanged. The harmonic content influences the smoothness of the output currents i _u , i _v , i _w , i* _u , i* _v , i* _w . The lower the harmonic content, the closer the actual output current is to a desired shape, such as a sinusoidal shape. In 2 output currents i, i* are shown, each of which has the same sinusoidal fundamental wave but different harmonic content H1, H2. The output current i has a first, minimum harmonic content H1 and the associated output current i* has a second, higher harmonic content H2. Both output currents i, i* contribute to the generation of the same torque M, ie they correspond to the same operating point.

erzeugt, wie sind in dem Raumzeigerdiagramm gemäß 3 in der komplexen Ebene a, jβ dargestellt sind. Die Spannungsraumzeiger $\stackrel{\rightharpoonup }{U_0},\stackrel{\rightharpoonup }{U_7}$

sind dabei passive Nullspannungsraumzeiger und die Spannungsraumzeiger $\stackrel{\rightharpoonup }{U_1},\stackrel{\rightharpoonup }{U_2},\stackrel{\rightharpoonup }{U_3},\stackrel{\rightharpoonup }{U_4},\stackrel{\rightharpoonup }{U_5},\stackrel{\rightharpoonup }{U_6}$

sind aktive Grundspannungsraumzeiger. Zur Erzeugung einer bestimmten Ausgangsspannung u_u, u_v, u_w wird dabei eine Abfolge von Spannungsraumzeiger bestimmt, welche nacheinander ausgegeben werden. Für den effizienten Betriebsmodus beinhaltet die Abfolge die Nullspannungsraumzeiger $\stackrel{\rightharpoonup }{U_0},\stackrel{\rightharpoonup }{U_7}.$

Für den ineffizienten Betriebsmodus sind die Nullspannungsraumzeiger $\stackrel{\rightharpoonup }{U_0},\stackrel{\rightharpoonup }{U_7}.$

zumindest teilweise durch die Grundspannungsraumzeiger $\stackrel{\rightharpoonup }{U_1},\stackrel{\rightharpoonup }{U_2},\stackrel{\rightharpoonup }{U_3},\stackrel{\rightharpoonup }{U_4},\stackrel{\rightharpoonup }{U_5},\stackrel{\rightharpoonup }{U_6}$

ersetzt, indem ein Nullspannungszeiger $\stackrel{\rightharpoonup }{U_0},\stackrel{\rightharpoonup }{U_7}$

durch zumindest zwei Grundspannungszeiger $\stackrel{\rightharpoonup }{U_1},\stackrel{\rightharpoonup }{U_2},\stackrel{\rightharpoonup }{U_3},\stackrel{\rightharpoonup }{U_4},\stackrel{\rightharpoonup }{U_5},\stackrel{\rightharpoonup }{U_6}$

$$

unterschiedlicher Vorzeichen repräsentiert wird. Beispielsweise kann ein Nullspannungszeiger $\stackrel{\rightharpoonup }{U_0},\stackrel{\rightharpoonup }{U_7}$

durch die Grundspannungsraumzeiger $\stackrel{\rightharpoonup }{U_2},\stackrel{\rightharpoonup }{U_5},$

ersetzt werden. Durch diese entgegengesetzten Grundspannungszeiger $\stackrel{\rightharpoonup }{U_2},\stackrel{\rightharpoonup }{U_5}$

wird ein Stromfluss aufgebaut und wieder abgebaut, welcher den Kurzzeitmittelwert nicht beeinflusst, jedoch eine Oberwelle ausbildet.Different pulse patterns are generated to provide the different harmonic contents H1, H2. The pulse patterns can be generated, for example, by means of space vector modulation. With space vector modulation, the output voltages u _u , _uv , u _w are generated using voltage space vectors $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_1},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102021111590A1\_0017.png,DE102021111590A1\_0020.png"\; state="\{\{state\}\}">u</figure-callout>}}_2},...\stackrel{\rightharpoonup }{u_7}$

generated as shown in the space vector diagram 3 are shown in the complex plane a, jβ. The stress space vector $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}$

are passive zero-stress space vectors and the stress space vectors $\stackrel{}{u_{}}$$\stackrel{\rightharpoonup }{{}_1},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102021111590A1\_0017.png,DE102021111590A1\_0020.png"\; state="\{\{state\}\}">u</figure-callout>}}_2},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="3"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_3},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="4"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_4},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="5"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_5},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="6"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_6}$

are active basic stress space vectors. To generate a specific output voltage u _u , u _v , u _w , a sequence of voltage space vectors is determined, which are output one after the other. For the efficient mode of operation, the sequence includes the zero voltage space vectors $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}.$

For the inefficient mode of operation are the zero voltage space vectors $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}.$

at least in part by the fundamental stress space vector $\stackrel{}{u_{}}$$\stackrel{\rightharpoonup }{{}_1},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102021111590A1\_0017.png,DE102021111590A1\_0020.png"\; state="\{\{state\}\}">u</figure-callout>}}_2},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="3"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_3},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="4"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_4},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="5"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_5},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="6"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_6}$

replaced by a zero voltage pointer $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}$

by at least two basic voltage vectors $\stackrel{}{u_{}}$$\stackrel{\rightharpoonup }{{}_1},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="DE102021111590A1\_0017.png,DE102021111590A1\_0020.png"\; state="\{\{state\}\}">u</figure-callout>}}_2},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="3"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_3},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="4"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_4},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="5"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_5},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="6"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_6}$

$$

of different signs is represented. For example, a zero voltage pointer $\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}$

through the fundamental stress space vector $\stackrel{}{u_{}}$$\stackrel{\rightharpoonup }{{}_2},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="5"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_5},$

be replaced. Through these opposing fundamental voltage phasors $\stackrel{}{u_{}}$$\stackrel{\rightharpoonup }{{}_2},\stackrel{\rightharpoonup }{{\mathrm{<figure-callout\; id="5"\; label="u"\; filenames="DE102021111590A1\_0017.png"\; state="\{\{state\}\}">u</figure-callout>}}_5}$

a current flow is built up and then dissipated again, which does not affect the short-term mean value, but forms a harmonic.

Alternatively, the pulse patterns can be off-line optimized pulse patterns. A loss-optimal pulse pattern P1 and at least one power-loss-increasing pulse pattern P2 are thus determined offline for each operating point. The control device 7 can then select the loss-optimal, offline-optimized pulse pattern P1 or the power loss-increasing, offline-optimized pulse pattern P2 for driving the inverter 3 depending on the heating requirement of the component 4 . In 4 shown. The pulse patterns P1, P2 differ, for example, with regard to their switching angles φ ₁ , φ ₁ , φ ₂ , φ _{2 *} . The switching angles φ ₁ , φ ₂ define the first pulse pattern P1 and generate, for example, the current i, which has low harmonics. The switching angles φ _{1 *} , φ _{2 *} define the second pulse pattern P2 and generate the current i*, which is afflicted with increased harmonics.

QUOTES INCLUDED IN DESCRIPTION

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Patent Literature Cited

• DE 102016211762 A1 [0002]

Claims (10)

Method for operating an electric drive unit (1) of a motor vehicle in different operating modes, wherein - to provide an operating mode with optimal power loss, output voltages (u _u , u _v , u _w ) of an inverter (3) of the drive unit (1) are modulated in such a way that output currents ( i _u , i _v , i _w ) of the inverter (3) for an electrical machine (2) of the drive unit (1) have a first harmonic content (H1), and - for providing an operating mode that increases power loss for heating at least one component (4) of the motor vehicle, the output voltages (u _u , u _v , u _w ) are modulated in such a way that the output currents (i* _u , i* _v , i* _w ) have a second harmonic content (H2) that is greater than the first harmonic content (H1). , characterized in that for a specific operating point of the electrical machine (2) by means of a pulse method in each case to the power loss-optimal operation s mode corresponding first pulse pattern and a second pulse pattern corresponding to the operating mode that increases power loss are generated, by which the same short-term average values of the output voltages ( _{u u} , uv , u _w ) are modulated, so that the drive unit (1) changes from one operating mode to the other operating mode without Change in the operating point is transferred. procedure after claim 1 , characterized in that the power loss-increasing operating mode of the drive unit (1) is provided when the at least one component (4) of the motor vehicle sends a heating request signal. procedure after claim 1 or 2 , characterized in that the pulse patterns are generated by means of a pulse method designed as space vector modulation, the first pulse patterns being zero-voltage space vectors $\left(\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}\right)$

and the respective second pulse patterns corresponding to the same operating point have at least two basic voltage space vectors $\left(\stackrel{\rightharpoonup }{u_1},\stackrel{\rightharpoonup }{u_2},\stackrel{\rightharpoonup }{u_3},\stackrel{\rightharpoonup }{u_4},\stackrel{\rightharpoonup }{u_5},\stackrel{\rightharpoonup }{u_6}\right)$

have different signs, which at least a part of the zero voltage space vector $\left(\stackrel{\rightharpoonup }{u_0},\stackrel{\rightharpoonup }{u_7}\right)$

of the associated first pulse pattern. procedure after claim 3 , characterized in that for setting a level of the power loss, a proportion and/or a period of time of the basic voltage space vector $\left(\stackrel{\rightharpoonup }{u_1},\stackrel{\rightharpoonup }{u_2},\stackrel{\rightharpoonup }{u_3},\stackrel{\rightharpoonup }{u_4},\stackrel{\rightharpoonup }{u_5},\stackrel{\rightharpoonup }{u_6}\right)$

different signs is specified. procedure after claim 1 or 2 , characterized in that the pulse patterns are generated by means of a pulse method based on offline-optimized pulse patterns (P1, P2). procedure after claim 5 , characterized in that the first pulse patterns (P1) have first switching angles (φ ₁ , φ ₂ ) for switches of the inverter (3), which are optimized with regard to a first, in particular minimal, power loss, and the respective second pulse patterns corresponding to the same operating point (P2) have second switching angles (φ _{1 *} , φ _{2 *} ), which are optimized with regard to a second, in particular maximum, power loss. procedure after claim 5 or 6 , characterized in that to set the level of the power loss, a pulse sequence control is carried out from at least a first offline-optimized pulse pattern (P1) and at least a second offline-optimized pulse pattern (P2), with a time ratio of the at least one first pulse pattern (P1) and of the at least one second pulse pattern (P2) is determined as a function of the amount of power loss. Control device (7) for an electric drive unit (1) of a motor vehicle, which is designed to carry out a method according to one of the preceding claims. Electrical drive unit (1) for a motor vehicle, comprising: - an electrical machine (2) for providing a torque (M), - an inverter (3) connected to the electrical machine (2), - at least one component (4) to be heated, and - a control device (7). claim 8 . Motor vehicle with an electric drive unit (1). claim 9 .

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