JP2012254763A - Control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the energy efficiency of a hybrid vehicle excellent.SOLUTION: The control device of the hybrid vehicle on which a battery where the electric power supplied from the external power source is stored is mounted, and which runs by using at least one of the engine and the electric motor as a driving source, switches the travel mode that drives the engine and the travel mode that stops the engine according to the map having the traveling power and the vehicle speed as parameters, and at least determined in consideration of the efficiency of the engine. The engine is driven in a traveling state where the overall efficiency of the hybrid vehicle is better when the engine is driven than when stopped. Oppositely, the engine is stopped in the traveling state to stop when the overall efficiency of the hybrid vehicle is better when the engine is stopped than when driven. As the result that the engine is driven, the increase amount of the electric power supplied to the electric motor is controlled, and decrease of the remaining capacity of the battery is controlled.

Description

  The present invention relates to a vehicle control device, and more particularly, to control a vehicle that is mounted with a battery that stores electric power supplied from an external power source and that uses at least one of an engine and an electric motor as a drive source. Regarding technology.

  Hybrid vehicles equipped with an engine and an electric motor as drive sources are known. A hybrid vehicle is equipped with a power storage device such as a battery for storing electric power supplied to the electric motor. The battery is charged with electric power generated by a generator driven by an engine, electric power regenerated using an electric motor when the vehicle is decelerated, and the like. A hybrid vehicle, also called a plug-in hybrid vehicle, can charge a battery supplied from a power supply external to the vehicle.

  In a plug-in hybrid vehicle, the battery can be fully charged. Therefore, it is possible to travel using only the electric motor for a relatively long time. As one of the methods using such characteristics, as described in Japanese Patent Application Laid-Open No. 2011-915 (Patent Document 1), EV traveling that travels only with an electric motor according to electric power cost and fuel cost. It has been proposed to increase or decrease the area.

JP 2011-915 A

  However, the distance that can be traveled by only the electric motor is limited, and the engine must be driven when the remaining capacity of the battery decreases. Therefore, for example, when it is necessary to travel over a long distance, it is inevitable to drive the engine with the remaining capacity of the battery lowered. In a state where the remaining capacity of the battery is reduced, it is possible that sufficient electric power cannot be supplied to the electric motor to assist the engine with the electric motor. In this case, the engine must be driven even in an operating state where the engine is inefficient. Thus, overall energy efficiency can be degraded.

  The present invention has been made to solve the above-described problems, and an object thereof is to improve the energy efficiency of a vehicle.

  A control device for a vehicle that is mounted with a battery that stores electric power supplied from an external power source and that uses at least one of an engine and an electric motor as a drive source has travel power and vehicle speed as parameters. And a control means for switching between a travel mode for driving the engine and a travel mode for stopping the engine according to a map determined in consideration of at least engine efficiency.

  According to this configuration, in consideration of the engine efficiency, the engine can be driven in a traveling state where the engine efficiency is good, for example, and the rate of decrease in the remaining capacity of the battery can be reduced. Therefore, electric power necessary for running the vehicle using the electric motor can be left in the battery over a relatively long distance. Therefore, the engine can be stopped in an operating state where the efficiency of the engine is low, and the travel distance that allows the vehicle to travel using the electric motor can be increased. As a result, overall vehicle energy efficiency can be improved.

It is a schematic block diagram which shows a plug-in hybrid vehicle. It is a figure which shows the alignment chart of a power split device. It is a figure (the 1) which shows the electric system of a plug-in hybrid vehicle. It is FIG. (2) which shows the electrical system of a plug-in hybrid vehicle. It is a figure which shows the area | region where CS mode is selected, and the area | region where CD mode is selected. It is a figure which shows the period when an engine drives. It is a figure which shows the fuel consumption optimal line which determines the operating point of an engine. It is a figure which shows SOC of a battery in long distance operation mode. It is a figure which shows a driving | running | working possible distance and driving | running | working planned distance. FIG. 6 is a diagram showing a map used to increase battery power.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
Referring to FIG. 1, an engine 100, a first motor generator 110, a second motor generator 120, a power split mechanism 130, a speed reducer 140, and a battery 150 are mounted on the plug-in hybrid vehicle. .

  Engine 100, first motor generator 110, second motor generator 120, and battery 150 are controlled by an ECU (Electronic Control Unit) 170. ECU 170 may be divided into a plurality of ECUs.

  This vehicle travels by driving force from at least one of engine 100 and second motor generator 120. That is, either one or both of engine 100 and second motor generator 120 is automatically selected as a drive source according to the operating state.

  For example, when the accelerator opening is small and the vehicle speed is low, the plug-in hybrid vehicle runs using only the second motor generator 120 as a drive source. In this case, engine 100 is stopped. However, the engine 100 may be driven for power generation or the like.

  Further, when the accelerator opening is large, the vehicle speed is high, or the remaining capacity (SOC: State Of Charge) of battery 150 is small, engine 100 is driven. In this case, the plug-in hybrid vehicle travels using only engine 100 or both engine 100 and second motor generator 120 as drive sources.

  Further, the vehicle is controlled in one of a control mode of a CS (Charge Sustaining) mode, a CD (Charge Depleting) mode, and a long-distance driving mode. For example, when the driver turns on the switch 172, the long distance driving mode is selected. When the switch 172 is off, the CS mode and the CD mode are automatically switched.

  In the CS mode, the plug-in hybrid vehicle travels while maintaining the electric power stored in the battery 150 at a predetermined target value.

  In the CD mode, the plug-in hybrid vehicle travels mainly using only the driving force of the second motor generator 120 using the power without maintaining the power stored in the battery 150 for traveling. However, in the CD mode, the engine 100 can be driven to supplement the driving force when the accelerator opening is high and the vehicle speed is high.

  In the long distance operation mode, the engine 100 is driven while the second motor generator 120 is driven, and the engine 100 is driven when the engine 100 is in an efficient driving state, and the engine 100 is stopped when the engine 100 is in an inefficient driving state.

  The CS mode may be described as the HV mode. Similarly, the CD mode may be described as an EV mode. The CS mode, the CD mode, and the long distance operation mode will be further described later.

  The engine 100 is an internal combustion engine. As the fuel / air mixture burns in the combustion chamber, the crankshaft as the output shaft rotates. The exhaust gas discharged from the engine 100 is purified by the catalyst 102 and then discharged outside the vehicle. The catalyst 102 exhibits a purification action when the temperature is increased to a predetermined activation temperature. The catalyst 102 is warmed up by utilizing the heat of the exhaust gas. The catalyst 102 is, for example, a three-way catalyst.

  The air-fuel ratio of the engine 100 is detected from the exhaust gas by the air-fuel ratio sensor 104. Further, the temperature of the cooling water of engine 100 is detected by temperature sensor 106. The output of the air-fuel ratio sensor 104 and the output of the temperature sensor 106 are input to the ECU 170.

  Engine 100, first motor generator 110, and second motor generator 120 are connected via power split mechanism 130. The power generated by the engine 100 is divided into two paths by the power split mechanism 130. One is a path for driving the front wheels 160 via the speed reducer 140. The other is a path for driving the first motor generator 110 to generate power.

  First motor generator 110 is a three-phase AC rotating electric machine including a U-phase coil, a V-phase coil, and a W-phase coil. First motor generator 110 generates power using the power of engine 100 divided by power split mechanism 130. The electric power generated by the first motor generator 110 is selectively used according to the running state of the vehicle and the remaining capacity of the battery 150. For example, during normal traveling, the electric power generated by first motor generator 110 becomes electric power for driving second motor generator 120 as it is. On the other hand, when the SOC of battery 150 is lower than a predetermined value, the electric power generated by first motor generator 110 is converted from AC to DC by an inverter described later. Thereafter, the voltage is adjusted by a converter described later and stored in the battery 150.

  When first motor generator 110 is acting as a generator, first motor generator 110 generates negative torque. Here, the negative torque means a torque that becomes a load on engine 100. When first motor generator 110 is supplied with electric power and acts as a motor, first motor generator 110 generates positive torque. Here, the positive torque means a torque that does not become a load on the engine 100, that is, a torque that assists the rotation of the engine 100. The same applies to the second motor generator 120.

  Second motor generator 120 is a three-phase AC rotating electric machine including a U-phase coil, a V-phase coil, and a W-phase coil. Second motor generator 120 is driven by at least one of the electric power stored in battery 150 and the electric power generated by first motor generator 110.

  The driving force of the second motor generator 120 is transmitted to the front wheels 160 via the speed reducer 140. As a result, the second motor generator 120 assists the engine 100 or causes the vehicle to travel by the driving force from the second motor generator 120. The rear wheels may be driven instead of or in addition to the front wheels 160.

  During regenerative braking of the plug-in hybrid vehicle, the second motor generator 120 is driven by the front wheels 160 via the speed reducer 140, and the second motor generator 120 operates as a generator. Accordingly, second motor generator 120 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by second motor generator 120 is stored in battery 150.

  Power split device 130 includes a planetary gear including a sun gear, a pinion gear, a carrier, and a ring gear. The pinion gear engages with the sun gear and the ring gear. The carrier supports the pinion gear so that it can rotate. The sun gear is connected to the rotation shaft of first motor generator 110. The carrier is connected to the crankshaft of engine 100. The ring gear is connected to the rotation shaft of second motor generator 120 and speed reducer 140.

  The engine 100, the first motor generator 110, and the second motor generator 120 are connected via a power split mechanism 130 that is a planetary gear, so that the rotational speeds of the engine 100, the first motor generator 110, and the second motor generator 120 are increased. As shown in FIG. 2, the relationship is connected by a straight line in the alignment chart.

  Returning to FIG. 1, the battery 150 is an assembled battery configured by further connecting a plurality of battery modules in which a plurality of battery cells are integrated in series. The voltage of the battery 150 is about 200V, for example. The battery 150 is charged with electric power supplied from a power source external to the vehicle in addition to the first motor generator 110 and the second motor generator 120. A capacitor may be used instead of or in addition to the battery 150.

  With reference to FIG. 3, the electrical system of the plug-in hybrid vehicle will be further described. The plug-in hybrid vehicle is provided with a converter 200, a first inverter 210, a second inverter 220, an SMR (System Main Relay) 230, a charger 240, and an inlet 250.

  Converter 200 includes a reactor, two npn transistors, and two diodes. One end of the reactor is connected to the positive electrode side of each battery, and the other end is connected to the connection point of the two npn transistors.

  Two npn-type transistors are connected in series. The npn transistor is controlled by the ECU 170. A diode is connected between the collector and emitter of each npn transistor so that a current flows from the emitter side to the collector side.

  For example, an IGBT (Insulated Gate Bipolar Transistor) can be used as the npn transistor. Instead of the npn type transistor, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) can be used.

  When the electric power discharged from the battery 150 is supplied to the first motor generator 110 or the second motor generator 120, the voltage is boosted by the converter 200. Conversely, when charging the battery 150 with the electric power generated by the first motor generator 110 or the second motor generator 120, the voltage is stepped down by the converter 200.

  System voltage VH between converter 200 and each inverter is detected by voltage sensor 180. The detection result of voltage sensor 180 is transmitted to ECU 170.

  First inverter 210 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, the V-phase arm, and the W-phase arm has two npn transistors connected in series. Between the collector and emitter of each npn-type transistor, a diode for passing a current from the emitter side to the collector side is connected. A connection point of each npn transistor in each arm is connected to an end portion different from neutral point 112 of each coil of first motor generator 110.

  First inverter 210 converts a direct current supplied from battery 150 into an alternating current and supplies the alternating current to first motor generator 110. The first inverter 210 converts the alternating current generated by the first motor generator 110 into a direct current.

  Second inverter 220 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, the V-phase arm, and the W-phase arm has two npn transistors connected in series. Between the collector and emitter of each npn-type transistor, a diode for passing a current from the emitter side to the collector side is connected. A connection point of each npn transistor in each arm is connected to an end portion different from neutral point 122 of each coil of second motor generator 120.

  Second inverter 220 converts a direct current supplied from battery 150 into an alternating current, and supplies the alternating current to second motor generator 120. Second inverter 220 converts the alternating current generated by second motor generator 120 into a direct current.

  Converter 200, first inverter 210, and second inverter 220 are controlled by ECU 170.

  SMR 230 is provided between battery 150 and charger 240. The SMR 230 is a relay that switches between a connected state and a disconnected state of the battery 150 and the electrical system. When SMR 230 is open, battery 150 is disconnected from the electrical system. When SMR 230 is closed, battery 150 is connected to the electrical system.

  That is, when SMR 230 is open, battery 150 is electrically disconnected from converter 200, charger 240, and the like. When SMR 230 is in a closed state, battery 150 is electrically connected to converter 200, charger 240, and the like.

  The state of SMR 230 is controlled by ECU 170. For example, when the ECU 170 is activated, the SMR 230 is closed. When the ECU 170 stops, the SMR 230 is opened.

  Charger 240 is connected between battery 150 and converter 200. As shown in FIG. 4, charger 240 includes an AC / DC conversion circuit 242, a DC / AC conversion circuit 244, an insulation transformer 246, and a rectifier circuit 248.

  The AC / DC conversion circuit 242 is a single-phase bridge circuit. The AC / DC conversion circuit 242 converts AC power into DC power based on a drive signal from the ECU 170. The AC / DC conversion circuit 242 also functions as a boost chopper circuit that boosts the voltage by using a coil as a reactor.

  The DC / AC conversion circuit 244 is composed of a single-phase bridge circuit. The DC / AC conversion circuit 244 converts the DC power into high-frequency AC power based on the drive signal from the ECU 170 and outputs it to the isolation transformer 246.

  Insulation transformer 246 includes a core made of a magnetic material, and a primary coil and a secondary coil wound around the core. The primary coil and the secondary coil are electrically insulated and connected to the DC / AC conversion circuit 244 and the rectification circuit 248, respectively. Insulation transformer 246 converts high-frequency AC power received from DC / AC conversion circuit 244 into a voltage level corresponding to the turn ratio of the primary coil and the secondary coil, and outputs the voltage level to rectifier circuit 248. The rectifier circuit 248 rectifies AC power output from the insulating transformer 246 into DC power.

  A voltage (voltage between terminals of the smoothing capacitor) between AC / DC conversion circuit 242 and DC / AC conversion circuit 244 is detected by voltage sensor 182, and a signal representing the detection result is input to ECU 170. The output current of charger 240 is detected by current sensor 184, and a signal representing the detection result is input to ECU 170. Further, the temperature of charger 240 is detected by temperature sensor 186, and a signal representing the detection result is input to ECU 170.

  Inlet 250 is provided, for example, on the side of a plug-in hybrid vehicle. A connector 310 of a charging cable 300 that connects the plug-in hybrid vehicle and an external power source 402 is connected to the inlet 250.

  Plug 320 of charging cable 300 is connected to an outlet 400 provided in the house. AC power is supplied to the outlet 400 from a power source 402 outside the plug-in hybrid vehicle.

  In a state where the plug-in hybrid vehicle and the external power supply 402 are connected by the charging cable 300, the power supplied from the external power supply 402 is charged to the battery 150. When the battery 150 is charged, the SMR 230 is closed.

  Hereinafter, the CS mode, the CD mode, and the long distance operation mode will be further described. For example, if the long-distance operation mode is not selected, the CS mode is selected when the SOC of the battery 150 is equal to or less than a threshold value as shown in FIG. If the SOC of battery 150 is greater than the threshold value, the CD mode is selected. The method for selecting the CS mode and the CD mode is not limited to this.

  In the CS mode and the CD mode, the plug-in hybrid vehicle travels by the driving force from at least one of the engine 100 and the second motor generator 120.

  As shown in FIG. 6, when the traveling power of the plug-in hybrid vehicle is smaller than the engine start threshold, the plug-in hybrid vehicle travels using only the driving force of the second motor generator 120. Accordingly, when the traveling power that has been equal to or higher than the engine start threshold value decreases to the engine start threshold value, ignition and fuel supply (fuel injection) to engine 100 are stopped in order to stop engine 100.

  On the other hand, when the traveling power of the plug-in hybrid vehicle exceeds the engine start threshold value, engine 100 is driven. Thus, the plug-in hybrid vehicle travels using the driving force of engine 100 in addition to or instead of the driving force of second motor generator 120. Further, the electric power generated by first motor generator 110 using the driving force of engine 100 is directly supplied to second motor generator 120.

  As apparent from FIG. 6, the region where the plug-in hybrid vehicle is controlled in the CS mode includes a region where engine 100 is stopped and a region where engine 100 is driven. Similarly, the region where the plug-in hybrid vehicle is controlled in the CD mode includes a region where engine 100 is stopped and a region where engine 100 is driven.

  The traveling power is calculated by the ECU 170 according to a map having parameters such as an accelerator pedal position (accelerator position) operated by a driver and a vehicle speed, for example. Note that the method of calculating the traveling power is not limited to this.

  The engine start threshold value in the CD mode is larger than the engine start threshold value in the CS mode. That is, the engine 100 is stopped in the CD mode and the plug-in hybrid vehicle travels only with the driving force of the second motor generator 120. The engine 100 is stopped in the CS mode and only the driving force of the second motor generator 120 is used. It is larger than the area where plug-in hybrid vehicles travel. Therefore, in the CD mode, the engine 100 is stopped, and control is performed so that the plug-in hybrid vehicle travels mainly only with the driving force of the second motor generator 120. On the other hand, the frequency at which engine 100 is driven in the CS mode is higher than the frequency at which engine 100 is driven in the CD mode. Therefore, in the CS mode, control is performed so that the plug-in hybrid vehicle travels efficiently using both engine 100 and second motor generator 120.

  Hereinafter, the engine start threshold value in the CS mode is also referred to as first engine start power. The engine start threshold value in the CD mode is also referred to as the second engine start power. As shown in FIG. 6, the second engine start power is larger than the first engine start power.

  The electric power charged in the battery 150 in the CD mode is made smaller than the electric power charged in the battery 150 in the CS mode. Specifically, in the CS mode, the charging power of battery 150 is determined according to the SOC of battery 150. Engine 100 is driven so that electric power corresponding to the determined charging electric power can be generated using first motor generator 110. On the other hand, in the CD mode, normally, the charging power of the battery 150 is set to zero. That is, in the CD mode, the electric power obtained by regenerative braking is charged in battery 150, but engine 100 for the purpose of charging battery 150 is not driven.

  Therefore, in the CD mode, the power stored in the battery 150, in particular, the power supplied from the power source 402 outside the plug-in hybrid vehicle is actively consumed. As a result, in the CD mode, ignition and fuel supply (fuel injection) to the engine 100 can be frequently stopped to stop the engine 100 as compared to the CS mode. That is, in the CD mode, the opportunities for operating the engine 100 are limited as compared to the CS mode.

  As shown in FIG. 7, the operating point of the engine 100, that is, the engine speed NE and the output torque TE are determined by the intersection of the output power and the optimum fuel consumption line. The output power is indicated by an isopower line. The optimum fuel consumption line is a curve connecting operating points where the engine 100 is efficient. The optimum fuel consumption line is predetermined by the developer based on the results of experiments and simulations.

  When long-distance operation mode is selected, engine 100, first motor generator 110, and second motor generator 120 are controlled using an optimum efficiency operating point map having travel power and vehicle speed as parameters.

  The optimum efficiency operating point map is created in advance by the developer based on the results of experiments and simulations as the operating point at which the overall efficiency of the hybrid vehicle is the best considering the efficiency of the engine 100 and various losses. Is done.

  In the long-distance operation mode, the operating point (for example, output power and rotation speed) of engine 100 and the operating point (for example, power) of battery 150, that is, the operating point of second motor generator 120 (for example, power) according to the optimum efficiency operating point map. ) Is determined. However, unlike the CD mode described above, when the traveling power is positive, the power of the battery 150 is positive. Therefore, electric power is discharged from battery 150, and second motor generator 120 is driven.

  As a result of determining the operating point of the engine 100 according to the optimal efficiency operating point map, in the long-distance driving mode, the driving state in which the overall efficiency of the hybrid vehicle is better when the engine 100 is driven than when the engine 100 is stopped (running) In a combination of power and vehicle speed, engine 100 is operated. On the contrary, the engine 100 is stopped in the traveling state where the overall efficiency of the hybrid vehicle is better when the engine 100 is stopped than when the engine 100 is operated.

  Therefore, as shown in FIG. 8, when the traveling power increases, in the CD mode, the SOC supplied to the second motor generator 120 increases, so that the SOC of the battery 150 rapidly decreases while the long distance operation mode. Then, as a result of operating engine 100, the amount of increase in power supplied to second motor generator 120 is suppressed, and the rate of decrease in SOC is suppressed as compared with CD mode.

  Therefore, it is possible to store in the battery 150 the electric power necessary to run the vehicle with only the second motor generator 120 over a longer distance. Therefore, engine 100 is stopped in the driving state where engine 100 is inefficient, and the travel distance in which the vehicle can travel using second motor generator 120 can be increased. Therefore, the overall energy efficiency of the vehicle can be improved.

  Since the relationship between the cruising distance in the CD mode and the cruising distance in the long-distance driving mode can be grasped by storing the cruising distance in each mode, in addition to the cruising distance in the CD mode, the long distance The cruising distance in the operation mode may be displayed on a meter or the like. Further, the travelable distance in the long distance driving mode may be learned according to the actual situation.

<Second Embodiment>
Hereinafter, a second embodiment will be described. In the present embodiment, as shown in FIG. 9, when the travelable distance in the long-distance driving mode is longer than the planned travel distance input by the user, according to the difference between the travelable distance and the planned travel distance. The second embodiment is different from the first embodiment in that the power discharged from the battery 150 is increased and the output power of the engine 100 is reduced.

  The travelable distance includes the SOC of the battery 150, the SOC reduction rate, the vehicle speed, the accelerator opening, and the like as parameters, and is calculated by the ECU 170 based on a map created in advance by a developer. The method for calculating the travelable distance is not limited to this. The travelable distance may be learned in consideration of the use situation of the user.

  The estimated travel distance is manually input by the user using an input interface or the like. The estimated travel distance may be input by using a mobile phone or the like. The distance to the destination registered in the navigation system may be used as the planned travel distance.

  For the electric power discharged from battery 150 (that is, the power of second motor generator 120), for example, a constant determined according to the map shown in FIG. 10 is determined according to the optimum efficiency operating point map described in the first embodiment. Increased by multiplying 150 powers. The constants are not limited to those shown in FIG.

  As shown in FIG. 10, the map in which the constants are defined includes at least a difference between the travelable distance and the planned travel distance and SOC as parameters. A predetermined constant may be added to the power of the battery 150 determined according to the optimum efficiency operating point map.

  The output power of engine 100 is reduced by an amount corresponding to the increase in power of battery 150. Because the output power of engine 100 is reduced, the operating point of engine 100 changes along the fuel efficiency optimal line.

  In this way, it is possible to reduce the electric power remaining in the battery 150 when it arrives at the destination and charged by the power supply 402 outside the vehicle. Therefore, the power charged by the external power source 402 can be consumed without waste.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  100 Engine, 102 Catalyst, 110 First motor generator, 120 Second motor generator, 130 Power split mechanism, 140 Reducer, 150 Battery, 160 Front wheel, 170 ECU, 172 Switch, 200 Converter, 210 First inverter, 220 Second Inverter, 240 charger, 242 AC / DC conversion circuit, 244 DC / AC conversion circuit, 246 insulation transformer, 248 rectifier circuit, 250 inlet, 300 charging cable, 310 connector, 320 plug, 400 outlet, 402 power supply.

Claims (1)

A control device for a vehicle that is mounted with a battery that stores electric power supplied from an external power source and that uses at least one of an engine and an electric motor as a drive source,
Vehicle having a running power and a vehicle speed as parameters, and a control means for switching between a running mode for driving the engine and a running mode for stopping the engine according to a map determined in consideration of at least engine efficiency Control device.

Images