Exhaust gas aftertreatment system for internal combustion engine and method for controlling exhaust gas aftertreatment system

Abstract

The present invention relates to an exhaust gas aftertreatment system (100) for treating exhaust gas from an internal combustion engine, wherein the exhaust gas aftertreatment system (100) comprises: an exhaust gas catalyst (110) comprising an exhaust gas catalytic part and a heating element (120), wherein the heating element (120) is configured to heat the exhaust gas catalytic part, a voltage source (140) which supplies electric power to the heating element (120) so as to heat the heating element (120), a DC-DC converter (170) which is configured to control the supply of electric power from the voltage source (140) to the heating element (120), and a control unit (200) which is configured to control the DC-DC converter (170) based on the electric power required to heat the exhaust gas catalytic part.

Description

Technical Field

[0001] The invention relates to an exhaust gas aftertreatment system for treating exhaust gases from an internal combustion engine and to a method for controlling an exhaust gas aftertreatment system for an internal combustion engine. Background Art

[0002] The exhaust gas aftertreatment system is particularly used for vehicles using internal combustion engines to treat their exhaust gas to reduce the exhaust gas emissions of the internal combustion engine. Therefore, the exhaust gas aftertreatment system includes components such as an exhaust gas catalyst. The exhaust gas catalyst treats the exhaust gas emissions by chemical oxidation-reduction. The exhaust gas catalyst therefore includes an exhaust gas catalytic part, through which the exhaust gas flows and in which chemical oxidation-reduction occurs.

[0003] The required operating temperature for the exhaust catalytic part is usually in the region of more than 200°C. To reach this temperature, the exhaust catalytic converter usually uses the heat of the exhaust gas itself. This means that in the first moments after a cold start of the internal combustion engine, the exhaust catalytic converter is not operating at the required temperature level. If the exhaust catalytic converter is not operating at the required temperature level, the emissions of the internal combustion engine cannot be reduced as desired. In particular, the initial emissions after a cold start of the internal combustion engine are exacerbated by the higher combustion efficiency of modern internal combustion engines, which results in lower exhaust gas temperatures. Lower exhaust gas temperatures mean that the exhaust catalytic converter takes longer to reach operating temperature, which therefore results in higher emissions.

[0004] This is also a problem for hybrid vehicles because, by its nature, the internal combustion engine will run intermittently, so even during operation of the hybrid vehicle this may not be sufficient to raise the temperature of the exhaust catalyst to its operating temperature.

[0005] To counteract these problems, exhaust gas catalysts including heating elements are used. The heating element is configured to heat the exhaust gas catalytic portion of the exhaust gas catalyst during operation of the internal combustion engine. The heating element is typically supplied with electrical power from a voltage source. The electrical power required to heat the heating element may be between 2 kW and 10 kW. Due to the high electrical power requirements of the heating element, most of the required electrical power is typically provided from the vehicle's alternator or starter generator.

[0006] Control of the electrical power supply is usually achieved by an on-off control switch. In case the heating element is connected to the power supply network via an on-off switch, it is difficult to handle sudden power consumption on the network due to the high electrical power demand of the heating element. When the heating element is suddenly disconnected from the power supply network via the on-off switch, transient pulses may appear on the power supply network.

[0007] In the event of a sudden connection of the heating element to the power supply network and in the event of a sudden disconnection of the heating element from the power supply network, the entire network may become unstable or high-energy pulses may appear on the network, which may damage or destroy control units or other parts of the network.

[0008] US2010 / 212981 A1 discloses a system and a control module for controlling an electrically heated catalyst, which includes: a remote start module that generates a remote start signal; a catalyst control module that controls the electrical heating of the catalyst based on the remote start signal; and an engine control module that starts the engine after preheating and / or when a vehicle requirement satisfies a defined request.

[0009] JP 2009-189921 A discloses a current control system for use in a catalyst device heated by electric current, which is assembled together with the catalyst device heated by electric current, and the system includes: a catalyst carrier, which heats the catalyst carried by the increase in its temperature caused by electric current, and is characterized in that the current resistance changes according to its temperature change; first and second temperature sensors, which are arranged on the catalyst carrier; and a controller, which controls the current of the catalyst carrier according to information from the first and second temperature sensors.

[0010] US Pat. No. 5,261,230 A discloses a device for controlling the heating of a catalyst arranged in an exhaust passage of an engine. Summary of the invention

[0011] An object of the present disclosure is to provide an exhaust gas aftertreatment system and a method for controlling an exhaust gas aftertreatment system, with which a reliable and safe operation of the exhaust gas aftertreatment system can be achieved.

[0012] This object is achieved by an exhaust gas aftertreatment system having the features according to the present disclosure and a method for controlling an exhaust gas aftertreatment system having the features according to the present disclosure.

[0013] According to the present disclosure, an exhaust gas aftertreatment system for treating exhaust gas from an internal combustion engine comprises:

[0014] an exhaust gas catalyst comprising an exhaust gas catalytic portion and a heating element, wherein the heating element is configured to heat the exhaust gas catalytic portion,

[0015] a voltage source which supplies electrical power to the heating element in order to heat the heating element,

[0016] a DC-DC converter configured to control the supply of electrical power from the voltage source to the heating element, and

[0017] - a control unit configured to control the DC-DC converter based on the electrical power required for heating the exhaust catalytic portion.

[0018] The exhaust gas catalyst comprises an exhaust gas catalytic part and a heating element. In the exhaust gas catalytic part, a catalytic action takes place to reduce exhaust gas emissions. The heating element is configured to heat the exhaust gas catalytic part. According to one embodiment, the heating element is configured to selectively heat the exhaust gas catalytic part during operation of the exhaust gas aftertreatment system. According to one embodiment, the heating element is arranged upstream of the exhaust gas catalytic part relative to the flow direction of the exhaust gas through the internal combustion engine. According to another embodiment, it is also conceivable that the heating element is arranged downstream of the exhaust gas catalytic part in the exhaust gas flow direction. According to another embodiment, the exhaust gas catalyst comprises two heating elements, wherein one of the two heating elements is arranged upstream of the exhaust gas catalytic part in the exhaust gas flow direction, and the other of the two heating elements is arranged downstream of the exhaust gas catalytic part in the exhaust gas flow direction. Electrical power is supplied to the heating element by a voltage source. The voltage source is, for example, a battery or a rechargeable battery. The exhaust gas catalytic part is heated to a predetermined temperature by the heating element only when the temperature of the exhaust gas catalytic part is below a threshold temperature required for adequate exhaust gas aftertreatment. This is the case, for example, immediately after a cold start of the internal combustion engine. It is therefore not necessary to heat the exhaust gas catalytic converter by the heating element during the entire operating time of the internal combustion engine.

[0019] According to one embodiment, the heating element comprises a honeycomb structure or a matrix structure. According to this embodiment, an electric current flows from a voltage source through the honeycomb structure or the matrix structure. The honeycomb structure or the matrix structure acts as an ohmic resistor. As a result, the honeycomb structure or the matrix structure is heated and supplies heat to the exhaust gas catalytic part. Therefore, the temperature of the heating element directly depends on the electric power supplied by the voltage source.

[0020] A DC-DC converter is an electronic circuit or electromechanical device that converts a direct current source from one voltage level to another voltage level, so a DC-DC converter can be used to control the supply of electrical power to an electrical device. The advantage of a DC-DC converter is that electrical devices that require high electrical power can be safely connected or disconnected without damaging the power supply network. The DC-DC converter can therefore be used to connect or disconnect the heating element from the voltage source, and with the DC-DC converter, the output voltage supplied to the heating element can be safely controlled. Compared with conventional on-off switches, the DC-DC converter has a high efficiency level, so it can reduce the generation of unwanted heat. With a DC-DC converter, the supply of electrical power from the voltage source to the heating element can be safely and reliably controlled. When the DC-DC converter closes the circuit, the power consumption of the heating element enables the flow of electrical power from the voltage source to the heating element to be safely and reliably controlled without transient pulses on the power grid. With a DC-DC converter that controls the supply of electrical power from the voltage source to the heating element, even if the power supply from the voltage source to the heating element is constantly switched between on and off, it will not so easily cause instability in the power grid of the exhaust gas aftertreatment system. The DC-DC converter handles such sudden connections or disconnections without damaging the exhaust gas aftertreatment system's electrical network.

[0021] The control unit is configured to control the DC-DC converter based on the electric power required to heat the exhaust gas catalytic portion. In other words, if the heating element should heat the exhaust gas catalytic portion, the control unit controls the DC-DC converter to supply electric power from the voltage source to the heating element to heat the exhaust gas catalytic portion. In addition, the control unit is further configured to control the DC-DC converter to disconnect the voltage source from the heating element so that no electric power flows from the voltage source to the heating element.

[0022] According to the present disclosure, the control unit controls the supply of electric power from the voltage source to the heating element through a DC-DC converter to control the temperature of the exhaust gas catalytic part. By combining the control unit with the DC-DC converter, the supply of electric power from the voltage source to the heating element can be controlled in a manner that does not damage the power grid of the exhaust gas aftertreatment system during connection or disconnection of the heating element from the voltage source. This makes the entire exhaust gas aftertreatment system reliable and robust.

[0023] According to one embodiment, the DC-DC converter is a buck converter. A buck converter is a DC-DC converter that gradually reduces the voltage from its input to its output (by gradually increasing the current). With a buck converter, the supply of electrical power from the voltage source to the heating element can advantageously be controlled in such a way that the electrical network of the exhaust gas aftertreatment system is not overloaded if the heating element is connected to the voltage source via the buck converter or if the heating element is disconnected from the voltage source via the buck converter. Furthermore, energy pulses that may occur on the electrical network when the heating element is disconnected or connected to the voltage source can be reduced by the buck converter. The buck converter makes the entire exhaust gas aftertreatment system more reliable and robust.

[0024] In one embodiment, the DC-DC converter is a multiphase buck converter. A multiphase buck converter is a DC-DC converter comprising a plurality of groups, each of which comprises switches with corresponding inductances, wherein the groups are connected in parallel with each other. With such a converter, the power can be increased and the stepless current can be regulated. With a multiphase buck converter, the supply of electrical power from the voltage source to the heating element can be controlled in such a way that the power grid and, in particular, the entire exhaust gas aftertreatment system are not damaged during the disconnection of the heating element from the voltage source or the connection of the heating element to the voltage source. The multiphase buck converter can be adjusted according to the power demand of the heating element so that, in particular, during the on-off switching of the supply of electrical power from the voltage source to the heating element, the power grid is not exposed to transient energy pulses. With a multiphase buck converter, the supply of electrical power from the voltage source to the heating element can be achieved in a very reliable and robust manner.

[0025] In one embodiment, the DC-DC converter is configured to control the supply of electric power from the voltage source to the heating element during the ramp-up and / or ramp-down process of the electric power supply from the voltage source to the heating element. In addition, the exhaust gas aftertreatment system includes a main switch element, which is configured to control the supply of electric power from the voltage source to the heating element after the ramp-up process and / or before the ramp-down process. According to this embodiment, the control unit is configured to control the DC-DC converter and the main switch element based on the electric power required for heating the exhaust gas catalytic part. The ramp-up process is a process or stage in which the supply of electric power from the voltage source to the heating element is increased from zero load to the required load. The ramp-down process is a process or stage in which the supply of electric power from the voltage source to the heating element is reduced from the required load to zero load. According to this embodiment, the DC-DC converter is used to control the electric power from the voltage source to the heating element during the ramp-up and / or ramp-down process. This means that the control unit controls the DC-DC converter to increase the electric power supplied from the voltage source to the heating element from zero load to the required load, and the control unit controls the DC-DC converter to reduce the electric power supplied from the voltage source to the heating element from the required load to zero.

[0026] The main switch element is configured to control the supply of electric power from the voltage source to the heating element after the ramp-up process and / or before the ramp-down process. This means that the control unit controls the main switch element to control the supply of electric power from the voltage source to the heating element after the ramp-up process and / or before the ramp-down process. According to one embodiment, the main switch element is connected in parallel with respect to the DC-DC converter. For example, if the control unit controls the exhaust gas aftertreatment system to supply electric power from the voltage source to the heating element, the control unit controls the DC-DC converter to supply electric power from the voltage source to the heating element during the ramp-up process, and the control unit controls the main switch element to control the supply of electric power from the voltage source to the heating element after the ramp-up process.

[0027] According to one embodiment, the main switching element is activated once the required electrical power during the ramp-up process reaches 90% of its required load. Using a DC-DC converter during the ramp-up and / or ramp-down process of the electrical power supply from the voltage source to the heating element, the electrical power supply can be precisely controlled. This ensures the stability of the power grid of the exhaust gas after-treatment system. Using the main switching element to control the electrical power supply from the voltage source to the heating element after the ramp-up process and / or before the ramp-down process improves the efficiency of the entire circuit. With the configuration according to this embodiment, the entire exhaust gas after-treatment system and especially the circuit / grid is very reliable and robust even if the heating element is connected or disconnected from the voltage source.

[0028] According to one embodiment, the voltage source supplies a voltage of at least 36 volts, preferably 48 volts, to the exhaust gas aftertreatment system. It is conceivable that a hybrid vehicle is powered by an internal combustion engine and an electric motor. The electric motor is supplied with electrical energy by the voltage source. It is conceivable that the voltage source that supplies power to the electric motor driving the hybrid vehicle is also used to supply electrical power to the heating element of the exhaust gas catalyst. If this is the case, the number of voltage sources in such a vehicle can be reduced, which reduces the overall cost of the vehicle. The voltage source configured to supply power to the electric motor used to drive the vehicle typically supplies the vehicle with a voltage of at least 36 volts, preferably 48 volts. Therefore, the exhaust gas aftertreatment system is advantageously configured to handle a voltage of at least 36 volts, preferably 48 volts. This helps to reduce the number of different components and thus reduce costs.

[0029] According to the present disclosure, a method for controlling an exhaust gas aftertreatment system of an internal combustion engine is disclosed, wherein the exhaust gas aftertreatment system comprises an exhaust gas catalyst, the exhaust gas catalyst comprises an exhaust gas catalytic portion and a heating element, and wherein the exhaust gas aftertreatment system comprises a voltage source, wherein the voltage source supplies electric power to the heating element so as to heat the heating element, a DC-DC converter and a main switching element are provided, wherein the DC-DC converter and the main switching element are configured to control the supply of electric power from the voltage source to the heating element, wherein the method comprises the following steps:

[0030] - providing a signal, wherein the signal determines whether the exhaust gas catalytic portion is to be heated by the heating element;

[0031] - controlling a DC-DC converter to control a ramp-up of the electrical power supply from the voltage source to the heating element based on the signal;

[0032] - controlling the main switching element to control the supply of electrical power from the voltage source to the heating element after a ramp-up process and / or before a ramp-down process based on the signal;

[0033] - controlling a DC-DC converter to control the ramp-down of the electrical power supply from the voltage source to the heating element based on the signal.

[0034] If, for example, a sensor or sensor device in the exhaust gas aftertreatment system detects that the temperature of the exhaust gas catalytic part is below a predetermined threshold value (for example after a cold start), the control unit is configured to detect, for example, by means of a sensor device, that the temperature of the exhaust gas catalytic part is below a predetermined threshold value, and the control unit can provide a signal to heat the heating element accordingly. Thereafter, the DC-DC converter is controlled to increase the electrical power from the voltage source to the heating element. If the electrical power has reached a predetermined level, for example 90% of a defined electrical load, the main switching element is controlled to supply electrical power from the voltage source to the heating element. If, for example, the same sensor device detects that the temperature of the exhaust gas catalytic part is above a predetermined threshold value, the main switching element and the DC-DC converter are controlled to reduce the electrical power supplied by the voltage source to the heating element from a predetermined load to, for example, 50% of the maximum load, for example 20% of the maximum load, or zero load. The maximum load is the maximum electrical load that the heating element can withstand.

[0035] A DC-DC converter is also used in this ramp-down process. With the method according to the invention, the supply of electrical power from the voltage source to the heating element can be precisely controlled during the ramp-up and ramp-down processes, and grid stability is also ensured. The method for controlling an exhaust gas aftertreatment system is thus very reliable and robust.

[0036] According to another embodiment, a device for controlling an exhaust gas aftertreatment system of an internal combustion engine comprises a control unit configured to control the aforementioned method.

[0037] According to another embodiment, a computer program product includes instructions, which, when executed by a computer, cause the computer to implement the steps of the above method.

[0038] The device for controlling the exhaust gas aftertreatment system is, for example, an engine control unit. It is also conceivable that the device is part of the engine control unit or that the device is a further control unit arranged in a vehicle with an internal combustion engine. It is conceivable that the computer program product is executed in the engine control unit. It is also conceivable that the computer program product is executed by a further control unit arranged in a vehicle with an internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other advantageous embodiments of the present disclosure will become apparent through detailed description of exemplary embodiments in conjunction with the accompanying drawings. In the drawings:

[0040] Figure 1 shows a schematic circuit diagram of an exhaust gas aftertreatment system according to a first exemplary embodiment,

[0041] Figure 2 a first diagram showing a duty cycle of a circuit according to a first exemplary embodiment,

[0042] Figure 3 shows a schematic diagram of a circuit of an exhaust gas aftertreatment system according to a second exemplary embodiment,

[0043] Figure 4 a second diagram showing a duty cycle of a circuit according to a second exemplary embodiment,

[0044] Figure 5 A third diagram shows the operating cycle of the circuit of the second exemplary embodiment. DETAILED DESCRIPTION

[0045] Figure 1 First, the circuit of the exhaust gas aftertreatment system 100 is shown in a schematic manner. The exhaust gas aftertreatment system 100 includes an exhaust gas catalyst 110, wherein the exhaust gas catalyst 110 includes a heating element 120 and an exhaust gas catalytic portion. The heating element 120 is configured to heat the exhaust gas catalytic portion. The exhaust gas aftertreatment system 100 also includes a voltage source 140. The voltage source 140 is configured to supply electrical power to the heating element 120. According to this embodiment, the exhaust gas aftertreatment system 100 also includes a redundant switching element 160. According to this embodiment, the redundant switching element 160 is arranged to provide an additional shutoff path.

[0046] The exhaust aftertreatment system 100 further comprises a DC-DC converter 170. The DC-DC converter 170 is configured to control the supply of electrical power from the voltage source 140 to the heating element 120. According to this embodiment, the exhaust aftertreatment system 100 further comprises a capacitor 180. The capacitor 180 is arranged to smooth ripple current and smooth DC voltage variations.

[0047] The exhaust gas aftertreatment system 100 also includes a control unit 200 and a communication unit 210. The control unit 200 is configured to control the DC-DC converter 170 based on the electric power required to heat the exhaust gas catalytic portion of the exhaust gas catalyst 110. If the exhaust gas aftertreatment system is arranged in a vehicle, the communication unit 210 is configured to communicate with other parts of the vehicle. According to this exemplary embodiment, the DC-DC converter 170 is a three-phase (tree phase) buck converter. The three phases of the DC-DC converter 170 are controlled by the control unit 200. This Figure 1 140 , the DC-DC converter 170 is schematically shown by three arrows from the control unit 200 to the DC-DC converter 170. The DC-DC converter 170 is used during the ramp-up process of the electric power supply from the voltage source 140 to the heating element 120, during the steady-state power supply from the voltage source 140 to the heating element 120, and during the ramp-down process of the electric power supply from the voltage source 140 to the heating element 120. According to this embodiment, the entire power supply is controlled by the DC-DC converter. According to this embodiment, the voltage source 140, the capacitor 180, the DC-DC converter and the heating element 120 are connected to the engine ground 130.

[0048] The working cycle of the above embodiment can be Figure 2 Seen in. Figure 2 A first diagram 300 is schematically shown, which shows a current 330 flowing from a voltage source 140 to a heating element 120 over time 310. In a first time period, the current from the voltage source 140 to the heating element 120 is zero until the ramp-up process begins. The control unit 200 controls the DC-DC converter 170 accordingly to start the power supply. This can be seen in the first diagram 300, where, in the first time period, the current course 332 from the voltage source 140 to the heating element 120 increases from zero current to the required current over time 310. When the ramp-up process is completed, the current 330 flows from the voltage source 140 to the heating element 120 in a steady-state mode or phase. This can be seen in the first diagram 300, where the current course 332 remains constant over time 310 in a second time period. In a third time period after the second time period, the electrical power supply from the voltage source 140 to the heating element 120 is reduced to zero. This can be seen in the first diagram 300 in the current course 332, where the current 330 supplied from the voltage source 140 to the heating element 120 decreases to zero. The third time period is a ramp-down process. The entire operating cycle is controlled by the control unit 200 via the DC-DC converter 170.

[0049] Figure 3A second exemplary embodiment of a circuit of an exhaust gas aftertreatment system 100 is shown in a schematic manner. The second exemplary embodiment differs from the first exemplary embodiment in that the exhaust gas aftertreatment system 100 further comprises a main switching element 190. The main switching element 190 is configured to control the supply of electrical power from the voltage source 140 to the heating element 120 after a ramp-up process and / or before a ramp-down process, in particular during a steady-state power supply from the voltage source 140 to the heating element 120. Therefore, the control unit 200 of the second exemplary embodiment of the exhaust gas aftertreatment system 100 is further configured to control the main switching element 190.

[0050] Figure 4 In a second diagram 301 , a current flowing through a DC-DC converter 170 of a second exemplary embodiment of an exhaust gas aftertreatment system 100 during an operating cycle is shown.

[0051] Figure 5 In a third diagram 302 , a current flowing through the main switching element 190 of the second exemplary embodiment of the exhaust gas aftertreatment system 100 during an operating cycle is shown.

[0052] like Figure 4 and Figure 5 As can be seen in FIG. 1 , the DC-DC converter 170 is used to increase the power supply from the voltage source 140 to the heating element 120 during the ramp-up process, and to reduce the energy supply from the voltage source 140 to the heating element 120 during the ramp-down process. Figure 5 As can be seen in FIG. 1 , the main switching element is used to control the power supply from the voltage source 140 to the main switching element 190 after the ramp-up process and before the ramp-down process, thus during the steady state of the power supply.

[0053] The control unit 200 of the second exemplary embodiment of the exhaust gas aftertreatment system 100 is configured to control the power supply from the voltage source 140 to the heating element 120 through the DC-DC converter 170 during the ramp-up process, and to switch from the DC-DC converter 170 to the main switching element 190 after the ramp-up process or after a predefined part of the ramp-up process, for example, after 90% or 75% of the ramp-up process. The control unit 200 is also configured to control the electrical power supply from the voltage source 140 to the heating element 120 through the main switching element 190. The control unit 200 is also configured to change the electrical power supply from the main switching element 190 to the DC-DC converter 170 during the ramp-down process. The ramp-down process of the electrical power supply from the voltage source 140 to the heating element 120 is controlled by the DC-DC converter 170.

Claims

1. An exhaust gas aftertreatment system (100) for treating exhaust gas from an internal combustion engine, wherein: The exhaust gas aftertreatment system (100) comprises: an exhaust gas catalyst (110) comprising an exhaust gas catalytic part and a heating element (120), wherein the heating element (120) is configured to heat the exhaust gas catalytic part, a voltage source (140) which supplies electrical power to the heating element (120) in order to heat the heating element (120), a DC-DC converter (170) configured to control the supply of electrical power from the voltage source (140) to the heating element (120) during a ramp-up and / or ramp-down process of the supply of electrical power from the voltage source (140) to the heating element (120), a main switching element (190) configured to control the supply of electrical power from the voltage source (140) to the heating element (120) after the ramp-up process and / or before the ramp-down process, and - A control unit (200) configured to control the DC-DC converter (170) and the main switching element (190) based on a signal that the heating element (120) is to be heated and the electric power required to heat the exhaust gas catalytic portion.

2. The exhaust gas aftertreatment system (100) according to claim 1, wherein: The DC-DC converter (170) is a step-down converter.

3. The exhaust gas aftertreatment system (100) according to claim 2, wherein: The DC-DC converter (170) is a multi-phase buck converter.

4. The exhaust gas aftertreatment system (100) according to any one of the preceding claims, wherein: The voltage source (140) supplies a voltage of at least 36 volts to the exhaust aftertreatment system (100).

5. The exhaust gas aftertreatment system (100) according to any one of claims 1 to 3, wherein: The voltage source (140) supplies 48 volts to the exhaust aftertreatment system (100).

6. A method for controlling an exhaust gas aftertreatment system (100) of an internal combustion engine, wherein the exhaust gas aftertreatment system (100) comprises an exhaust gas catalyst (110), the exhaust gas catalyst (110) comprising an exhaust gas catalytic portion and a heating element (120), and wherein the exhaust gas aftertreatment system (100) comprises a voltage source (140), wherein the voltage source (140) supplies electric power to the heating element (120) so as to heat the heating element (120), a DC-DC converter (170) and a main switching element (190) are provided, wherein the DC-DC converter (170) and the main switching element (190) are configured to control the supply of electric power from the voltage source (140) to the heating element (120), wherein the method comprises the following steps: - providing a signal, wherein the signal determines whether the exhaust gas catalytic portion is to be heated by the heating element (120); - controlling a DC-DC converter (170) to control a ramp-up of the electrical power supply from the voltage source (140) to the heating element (120) based on the signal; - controlling the main switching element (190) to control the supply of electric power from the voltage source (140) to the heating element (120) after a ramp-up process and / or before a ramp-down process based on the signal; - controlling a DC-DC converter (170) to control the ramp-down of the electrical power supply from the voltage source (140) to the heating element (120) based on the signal.

7. The method according to claim 6, wherein: The DC-DC converter (170) is a step-down converter.

8. The method according to claim 7, wherein: The DC-DC converter (170) is a multi-phase buck converter.

9. A device for controlling an exhaust gas aftertreatment system (100) of an internal combustion engine, wherein: The device comprises a control unit (200) configured to control the method according to any one of claims 6, 7 or 8.

10. A computer program product comprising instructions which, when executed by a computer, cause the computer to implement the steps of the method according to any one of claims 6, 7 or 8.

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