Method and device for controlling a mild hybrid starter / generator of a mild hybrid electric vehicle

Abstract

A method for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle, comprising: acquiring data for controlling the MHSG (S100); determining, by a control device, a target torque of an internal combustion engine based on the data (S110); determining, by the control device, whether a pressure difference between a front end portion and a rear end portion of a particulate filter is equal to or greater than a first pressure based on the data (S120); determining, by the control device, an amount of engine torque loss of the internal combustion engine based on the pressure difference when the pressure difference is greater than or equal to the first pressure (S130); and performing, by the control device, torque compensation control of the MHSG based on the target engine torque and the amount of engine torque loss of the internal combustion engine.

Description

BACKGROUND OF THE INVENTIONField of the InventionThe present invention relates to a method and apparatus for controlling a mild hybrid starter / generator (e.g., mild hybrid starter / generator) (MHSG) of a mild hybrid electric vehicle, and more particularly, the present invention relates to a method and apparatus for controlling an MHSG of a mild hybrid electric vehicle that can prevent deterioration of performance of the mild hybrid electric vehicle in response to an increase in soot trapped in a particulate filter.Description of Related ArtGenerally, a hybrid electric vehicle uses an engine and a battery line source (e.g., power source) together. The hybrid electric vehicle efficiently combines engine torque and electric motor torque.Hybrid electric vehicles may be divided into a hard type and a mild type according to a power division ratio between an engine and an electric motor. In the case of the mild type of the hybrid electric vehicle (hereinafter referred to as the mild hybrid electric vehicle), a mild hybrid starter / generator (MHSG) configured to start the engine or generate electricity / current according to an output of the engine is used instead of an alternator. In the case of the hard type of hybrid electric vehicle, a drive motor configured to generate drive torque is used in addition to an integrated starter / generator (ISG) configured to start the engine or generate electricity.The MHSG may assist torque of the engine according to driving conditions of the vehicle, and may charge a battery (e.g., a 48V battery) by regenerative braking. Accordingly, the fuel efficiency of the mild hybrid electric vehicle can be improved.A particulate filter for trapping particulate matter (PM) contained in the exhaust gas is mounted in an exhaust pipe.In general, exhaust gas flowing out from an internal combustion engine through an exhaust manifold is introduced into and purified in a catalyst mounted on the exhaust pipe. Thereafter, noise of the exhaust gas is reduced while passing through a muffler, and then the exhaust gas is discharged into the air through an exhaust pipe. The catalyst purifies pollutants contained in the exhaust gas.As particulates (soot) trapped in the particulate filter become more (increase), the performance of the particulate filter is deteriorated and, in the worst case, the particulate filters are damaged. Accordingly, when an amount of the particulates trapped in the particulate filter is larger than a predetermined amount, the particulates are burned and removed. This is called regeneration of the particulate filter.Further, as the amount of particulates trapped in the particulate filter increases, the exhaust pressure of the engine increases and the output of the engine decreases. Accordingly, a method for compensating the output of the internal combustion engine while the regeneration of the particulate filter is performed is required.DE 195 32 128 A1 discloses a method for controlling an internal combustion engine, comprising:acquiring data for controlling the engine, determining, by a controller, a target torque of an engine,determining, by the controller, a loss amount of engine torque of the engine based on the data; andperforming, by the control device, torque compensation control of the engine using an electric motor based on the target torque of the engine and the loss amount of the engine torque of the engine. From DE 10 2005 018 575 A1 a method for controlling an internal combustion engine of a hybrid drive is known, which comprises: determining, by the control device, whether a pressure difference exists between a front end section and a rear end section of a particle filter, and controlling the internal combustion engine based on exhaust gas values determined from the pressure difference in order to maintain these in a desired range.EXPLANATION OF THE INVENTIONAn object of the present invention is to provide a method and an apparatus for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle, which have advantages of preventing deterioration of performance of the mild hybrid electric vehicle in response to an increase in soot / soot amount in a particulate filter.A method for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to the present invention includes: acquiring data for controlling the MHSG; determining a target torque of an engine based on the data; determining whether a pressure difference between a front end portion and a rear end portion of a particulate filter is equal to or greater than a first pressure based on the data; determining a loss amount of engine torque of the engine based on the pressure difference when the pressure difference is greater than or equal to the first pressure; and performing torque compensation control of the MHSG based on the target torque of the engine and the loss amount of engine torque of the engine.For example, the target engine torque may be determined based on a position of an accelerator pedal, a travel speed of the mild hybrid electric vehicle, and a speed of the engine.Performing the torque compensation control of the MHSG may include: determining a target torque of the MHSG based on the target torque of the engine and the loss amount of the engine torque of the engine; and controlling the MHSG to generate the target torque of the MHSG.The method may further include: determining whether the pressure difference is equal to or less than a second pressure during performing the torque compensation control of the MHSG; applying (e.g., ending) the torque compensation control of the MHSG when the pressure difference is equal to or less than the second pressure.An apparatus for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to the present invention includes: a data detector that detects data for controlling the MHSG; and a control device that determines a target torque of an engine based on the data and determines whether a pressure difference between a front end portion and a rear end portion of a particulate filter is equal to or greater than a first pressure, wherein the control device may be configured to determine a loss amount of engine torque of the engine based on the pressure difference when the pressure difference is equal to or greater than the first pressure, and may perform torque compensation control of the MHSG based on the target torque of the engine and the loss amount of engine torque of the engine.The controller may be configured to determine the target torque of the engine based on a position of an accelerator pedal, a travel speed of the mild hybrid electric vehicle, and a rotation speed of the engine.The controller may be configured to determine a target torque of the MHSG based on a target torque of the engine and the loss amount of the engine torque of the engine, and controls the MHSG to generate the target torque of the MHSG.The controller may be configured to determine whether the pressure difference is equal to or less than a second pressure during performing the torque compensation control of the MHSG, and may open (e.g., end) the torque compensation control of the MSHG when the pressure difference is equal to or less than the second pressure.The data detector may include an accelerator pedal position detector configured to detect a position of an accelerator pedal, a vehicle speed detector configured to detect a travel speed of the mild hybrid electric vehicle, an engine speed detector configured to detect the speed of the engine, and a pressure difference detector configured to detect the pressure difference between the front end portion and the rear end portion of the particulate filter.According to an exemplary embodiment of the present invention, even when the loss amount of the torque of the internal combustion engine is increased in response to an increase in the amount of soot trapped in the particulate filter, the performance of the mild hybrid electric vehicle can be prevented from being deteriorated by using the MHSG.The methods and apparatuses of the present invention have other features and advantages which will be apparent and are set forth in further detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.Brief Description of the DrawingsFIG. 1 is a diagram of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention. FIG. 2 is a schematic diagram of an exhaust system to which a method of controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention is applied. FIG. 3 is a diagram illustrating an apparatus for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention. FIG. 4 is a flow chart of a method for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention.It is to be understood that the appended drawings are not necessarily to scale, presenting an at least partially simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined, at least in part, by the particular intended application and use environment.In the figures, the same reference numerals refer to the same or similar parts of the invention throughout the several figures of the drawing.Detailed DescriptionReference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the invention will be described in connection with exemplary embodiments, it is to be understood that the present description is not intended to limit the invention to these exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, variations and other embodiments, which may be included within the scope of the claims appended hereto.In the following detailed description, various exemplary embodiments of the present application will be described in further detail with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. However, the present invention is not limited to the exemplary embodiments and may be modified in various ways.Parts not related to the invention are omitted to clearly describe the exemplary embodiments, and like reference numerals refer to like parts throughout the figures.Since each component in the drawings is arbitrarily selected for simple description, the present invention is not limited to the components illustrated in the drawings.FIG. 1 is a diagram of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention.As shown in FIG. 1, a mild hybrid electric vehicle according to an exemplary embodiment of the present invention includes an engine 10, a transmission 110, a mild hybrid starter / generator (MHSG) 120, a battery 130, a differential gear device 140, and a wheel 150.With respect to torque transmission of a mild hybrid electric vehicle, torque generated by the engine 10 is transmitted to an input shaft of the transmission 110, and torque output from an output shaft of the transmission 20 is transmitted to an axle via the differential gear device 140. The axle rotates the wheel 150 so that the mild hybrid electric vehicle travels by the torque generated by the engine 10.The MHSG 120 may start the engine 10 or generate electricity according to an output of the engine 10. Further, the MHSG 120 may assist the torque of the engine 10. The torque of the engine 10 may be used as a main torque, and a torque of the MHSG 120 may be used as an assist torque.The battery 130 may supply electricity to the MHSG 120, and may be charged by electricity recovered from the MHSG 120. The battery 30 may be a 48V battery. The mild hybrid electric vehicle may further include a low-voltage battery DC-DC converter (LDC) that converts a voltage supplied from the battery 130 into a low voltage, and a 12V battery that supplies a low voltage to electric loads (such as a headlight and an air conditioner).FIG. 2 is a schematic diagram of an exhaust system to which a method of controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention is applied.As shown in FIG. 2, an exhaust system may include the internal combustion engine 10, an exhaust pipe (e.g., exhaust pipe) 20, an exhaust gas recirculation (EGR) device 30, a denitrification catalyst (DeNOx catalyst) 40, a particulate filter 50, and a controller 60.The engine 10 burns fuel and air to convert chemical energy into mechanical energy. The internal combustion engine 10 is connected to an intake manifold 18 to receive the air in a combustion chamber 12, and exhaust gas generated in a combustion process is collected in the exhaust manifold 16 and discharged to an outside of the internal combustion engine 10. An injector 14 is mounted in the combustion chamber 12 to inject the fuel into the combustion chamber 12.A diesel engine is taken as an example herein, but a gasoline engine may also be used. In the case where the gasoline engine is used, the air-fuel mixture flows into the combustion chamber 12 through the intake manifold 18, and a spark plug is attached to an upper portion of the combustion chamber 12. Further, if a direct gasoline injector (GDI) engine is used, the injector 14 is mounted to the upper portion of the combustion chamber 12.The exhaust pipe 20 is connected to the exhaust manifold 16 to discharge the exhaust gas to the outside of the vehicle. The denitrification catalyst 40 and the particulate filter 50 are mounted on the exhaust pipe 20 and remove hydrocarbons, carbon monoxide and nitric oxide (NOx) contained in the exhaust gas.The exhaust gas recirculation device 30 is mounted on the exhaust pipe 20, and a part of the exhaust gas discharged from the engine 10 is fed back to the engine 10 through the exhaust gas recirculation device 30. further, the exhaust gas recirculation device 30 is connected to the intake manifold 18 to control the combustion temperature by mixing a part of the exhaust gas with the air. Such control of the combustion temperature is performed by controlling the amount of the exhaust gas fed back to the intake manifold 18 through control(s) by the control device 60.A first oxygen detector 72 is mounted on the exhaust pipe 20 downstream of the exhaust gas recirculation device 30, and the first oxygen detector 72 detects the amount of oxygen in the exhaust gas that passes through the exhaust gas recirculation device 30, and transmits a signal corresponding thereto to the control device 60.Further, a first temperature detector 74 is mounted on the exhaust pipe 20 downstream of the exhaust gas recirculation device 30, and detects the temperature of the exhaust gas passing through the exhaust gas recirculation device 30.The denitrification catalyst 40 is mounted on the exhaust pipe 20 downstream of the exhaust gas recirculation device 30. the denitrification catalyst 40 absorbs the nitrogen oxide (NOx) contained in the exhaust gas at a lean air-fuel ratio, and releases the absorbed nitrogen oxide (NOx) and reduces the nitrogen oxide (NOx) contained in the exhaust gas or the released nitrogen oxide (NOx) at a rich air-fuel ratio. A lean NOx trap (LNT) catalyst may be used as the denitrification catalyst 40. further, the denitrification catalyst 40 may oxidize carbon monoxide (CO) and hydrocarbon (HC) contained in the exhaust gas.A second oxygen detector 76 and a second temperature detector 78 are disposed on the exhaust pipe 20 downstream of the denitrification catalyst 40.The second oxygen detector 76 detects the amount of oxygen contained in the exhaust gas flowing into the particulate filter 50 and transmits a signal corresponding thereto to the controller 60. the controller 60 may perform the lean / rich control of the exhaust gas based on the detected values from the first oxygen detector 72 and the second oxygen detector 76.The second temperature detector 78 detects the temperature of the exhaust gas flowing into the particulate filter 50, and transmits a signal corresponding thereto to the controller 60.The particulate filter 50 is mounted on the exhaust pipe 20 downstream of the denitrification catalyst 40. The particulate filter 50 may be a diesel particulate filter (DPF) or a gasoline particulate filter (GPF), and traps particulates (PM) included in the exhaust gas.Further, an oxidizing catalyst may be coated on / on the particulate filter 50. Such an oxidizing catalyst oxidizes hydrocarbon and carbon monoxide contained in the exhaust gas to carbon dioxide and oxidizes nitrogen monoxide contained in the exhaust gas to nitrogen dioxide.A pressure difference detector 84 is mounted on the exhaust pipe 20. The pressure difference detector 84 detects the pressure difference between a front end portion and a rear end portion of the particulate filter 50, and transmits a signal corresponding thereto to the controller 60. the controller 60 may determine that the regeneration of the particulate filter 50 is required when the pressure difference detected by the pressure difference detector 84 is equal to or greater than a predetermined pressure. In this case, the injector 14 post-injects the fuel to combust the particulates trapped in the particulate filter 50.The controller 60 determines a driving state of the engine 10 based on the signals of the sensor and performs / the lean / rich control, and controls the regeneration of the particulate filter 50 based on the driving state of the engine 10.FIG. 3 is a diagram illustrating an apparatus for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention.As shown in FIG. 3, an apparatus for controlling a mild hybrid starter / generator (MHSG) according to an exemplary embodiment of the present invention includes a data detector 80 and the controller 60.The data detector 80 detects data for controlling the MHSG 120, and data(s) detected by the data detector 80 are transmitted to the controller 60. The data detector 80 may include an accelerator pedal position detector 81, a vehicle speed detector 82, an engine speed detector 83, and a / the pressure difference detector 84. The data detector 80 may further include other detectors (e.g., a brake pedal position detector, an SOC detector, and the like) for controlling the mild hybrid electric vehicle.The accelerator pedal position detector 81 detects a position of an accelerator pedal (i.e., the degree of depression of the accelerator pedal) and transmits a signal corresponding thereto to the controller 60.The vehicle speed detector 82 detects a speed of the mild hybrid electric vehicle and transmits a signal corresponding thereto to the control device 60.The engine speed detector 83 detects a rotation speed of the engine 10 and transmits a signal corresponding thereto to the controller 60. the engine speed detector 83 may detect the rotation speed of the engine 10 from a phase change of the crankshaft.The pressure difference detector 84 detects the pressure difference between a front end portion and a rear end portion of the particulate filter 50, and transmits a signal corresponding thereto to the controller 60.The controller 60 controls the MHSG 120 based on the data detected / have been detected by the data detector 80. For example, the controller 60 may determine a target torque of the engine 10 for driving / driving the mild hybrid electric vehicle based on the data, and may determine an engine torque of the engine 10 and a target torque of the MHSG 120 to satisfy the target torque (actually desired (but not achievable by the engine alone, as the case may be)) of the engine 10. For these purposes, the controller 60 may be implemented with one or more processors operated by a predetermined program. The predetermined program may include a series of commands for performing each step included / included in a method of controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention, which (method) is described below.FIG. 4 is a flow diagram of a method for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid starter according to an exemplary embodiment of the present invention.As shown in FIG. 4, a method of controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle according to an exemplary embodiment of the invention starts with, for example, acquiring data for controlling the MHSG 120 in step S 100. In other words, the accelerator position sensor 81 detects the position of the accelerator pedal, the vehicle speed sensor 82 detects the (running) speed of the mild hybrid vehicle, the engine speed detector 83 detects the speed of the engine 10, and the pressure difference detector 84 detects the pressure difference between the front end portion and the rear end portion of the particulate filter 50.The controller 60 determines a target torque of the engine 10 based on the data in step S 110. The controller 60 may determine the target torque of the engine 10 based on the position of the accelerator pedal, the (traveling) speed of the mild hybrid electric vehicle, and the rotational speed of the engine 10. The controller 60 may control the ignition timing, the fuel amount, and the air-fuel ratio to generate the engine torque of the engine 10.The controller 60 determines whether the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is equal to or greater than a first pressure in step S 120. The first pressure may be set by experiments. Specifically, the first pressure may be set by those skilled in the art based on a pressure difference between the front end portion and the rear end portion of the particulate filter 50 affecting an engine torque of the engine 10.When the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is less than the first pressure in step S 120, the controller 60 ends the method of controlling the MHSG according to an exemplary embodiment of the present invention. In the present case, the controller 60 may control the engine 10 and the MHSG 120 based on the detected engine torque of the engine 10 and the detected target torque of the MHSG 120.When the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is equal to or greater than the first pressure in step S 120, the controller 60 determines a loss amount of the engine torque of the engine 10 based on the pressure difference between the front end portion and the rear end portion of the particulate filter 50 in step S 130. The loss amount of the engine torque of the engine 10 may be set through experiments. More specifically, the loss amount of the engine torque increases as the pressure difference between the front end portion and the rear end portion of the particulate filter 50 increases.The controller 60 performs torque compensation control of the MHSG 120 based on the target torque of the engine 10 and the loss amount of the engine torque of the engine 10 in step S 140.More specifically, the controller 60 determines a target torque of the MHSG 120 based on the target torque of the engine 10 and the loss amount of the engine torque of the engine 10 in step S 141. The controller 60 determines the target torque of the MHSG 120 so that the torque of the MHSG 120 increases by the loss amount of the engine torque of the engine 10 to satisfy the target torque of the engine 10.The controller 60 controls the MHSG 120 to generate the target torque of the MHSG 120 in step S 142. Accordingly, even when the engine torque of the engine 10 decreases by increasing the pressure difference between the front end portion and the rear end portion of the particulate filter 50, the target torque of the engine 10 can be satisfied by compensating the engine torque of the engine 10 using the MHSG.While performing the torque compensation control of the MHSG 120, the controller 60 determines whether the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is equal to or less than a second pressure in step S 150. The second pressure may be set by experiments. More specifically, the second pressure may be set by those skilled in the art to determine whether the torque compensation control is not required. When the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is high, the control device 60 enters a regeneration mode of the particulate filter 50 and controls the injector 14 to re-inject the fuel to increase a temperature of the exhaust gas. Accordingly, the particulates trapped in the particulate filter 50 are burned, and the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is decreased.When the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is greater than the second pressure in step S 150, the controller 60 may return to step S 130.When the pressure difference between the front end portion and the rear end portion of the particulate filter 50 is equal to or less than the second pressure in step S 150, the controller 60 issues (terminates) the torque compensation control of the MHSG 120 in step S 160. In other words, the control device 60 may control the engine 10 and the MHSG 120 without considering the loss amount of the torque of the engine 10 in response to an increase in the pressure difference between the front end portion and the rear end portion of the particulate filter 50.As described above, according to an exemplary embodiment of the present invention, even when the loss amount of the torque of the engine 10 increases in response to an increase in soot trapped in the particulate filter 50, the performance of the mild hybrid electric vehicle can be prevented from degrading by using the MHSG 120.For convenience in explanation and accurate definition in the appended claims, the terms "upper", "lower", "inner", "outer", "up", "down", "up", "down", "front", "rear", "inside", "outside", "inward", "outward", "forward", "rearward", "inside", "outside", etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.The foregoing description of specific embodiments of the present invention has been made for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings without departing from the scope of the appended claims.

Claims

A method for controlling a mild hybrid starter / generator (MHSG) of a mild hybrid electric vehicle, comprising: acquiring data for controlling the MHSG (S 100), determining, by a controller, a target torque of an engine based on the data (S 110), determining, by the controller, whether a pressure difference between a front end portion and a rear end portion of a particulate filter is equal to or greater than a first pressure based on the data (S 120), determining, by the controller, an amount of loss of engine torque of the engine based on the pressure difference when the pressure difference is greater than or equal to the first pressure (S 130), and performing, by the controller, a torque loss of the engine based on the pressure difference, a torque compensation control of the MHSG based on the target torque of the engine and the loss amount of the engine torque of the engine.The method of claim 1, wherein the target engine torque is determined (S110) based on a position of an accelerator pedal, a travel speed of the mild hybrid electric vehicle, and a rotational speed of the engine.The method according to claim 1 or 2, wherein performing the torque compensation of the MHSG comprises: determining a target torque (S110) of the MHSG based on the target torque of the engine and the loss amount of the engine torque of the engine; and controlling the MHSG to generate the target torque of the MHSG.The method according to any one of claims 1-3, further comprising: determining whether the pressure difference is equal to or less than a second pressure during performing the torque compensation control of the MHSG (S150); and applying the torque compensation control of the MHSG (S160) when the pressure difference is equal to or less than the second pressure.An apparatus for controlling a mild hybrid starter / generator (MHSG) (120) of a mild hybrid electric vehicle, comprising: a data detector (80) that detects data for controlling the MHSG (120); and a control device (60) configured to determine a target torque of an internal combustion engine based on the data, and determine whether a pressure difference between a front end portion and a rear end portion of a particulate filter (50) is equal to or greater than a first pressure, wherein the control device (60) is configured to determine a loss amount of engine torque of the internal combustion engine based on the pressure difference when the pressure difference is equal to or greater than the first pressure, and configured to:, to perform torque compensation control of the MHSG ( 120) based on the target torque of the engine and the loss amount of the engine torque of the engine.The apparatus according to claim 5, wherein the controller (60) is configured to determine the target torque of the engine based on a position of an accelerator pedal, a travel speed of the mild hybrid electric vehicle, and a rotation speed of the engine.The apparatus according to claim 5 or 6, wherein the control device (60) is configured to determine a target torque of the MHSG (120) based on a target torque of the engine and the loss amount of the engine torque of the engine, and is configured to control the MHSG (120) to generate the target torque of the MHSG (120).The apparatus according to any one of claims 5-7, wherein the controller (60) is configured to determine whether the pressure difference is equal to or less than a second pressure during performing the torque compensation control of the MHSG (120), and to issue the torque compensation control of the MHSG (120) when the pressure difference is equal to or less than the second pressure.The apparatus according to any one of claims 5-8, wherein the data detector (50) comprises: an accelerator pedal position detector (81) configured to detect a position of an accelerator pedal, a vehicle speed detector (82) configured to detect a running speed of the mild hybrid electric vehicle, an engine speed detector (83) configured to detect the speed of the engine, and a pressure difference detector (84) configured to detect the pressure difference between the front end portion and the rear end portion of the particulate filter.

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