JP4325501B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a control device for a vehicle driven by an electric motor, and more particularly, to a control device for stopping a vehicle having a transformation mechanism (step-up and step-down).

  A vehicle equipped with a power train called a hybrid system combining an engine (for example, a known engine such as a gasoline engine or a diesel engine) and an electric motor has been developed and put into practical use. In such a vehicle, regardless of the amount of accelerator operation by the driver, the operation by the engine and the operation by the electric motor are automatically switched and controlled so as to obtain the highest efficiency. For example, when the engine is operated in a steady state to operate a generator that charges a secondary battery (battery), or the engine is operated intermittently during traveling according to the amount of charge of the secondary battery, etc. In such a case, the engine is repeatedly operated and stopped regardless of the amount of accelerator operation by the driver. That is, by operating the engine and the electric motor individually or in cooperation, it becomes possible to improve fuel consumption and significantly reduce exhaust gas.

  As described above, the engine of the hybrid vehicle is intermittently driven even during traveling, and the stop control is frequently performed. When engine stop control is performed, engine rotational energy (kinetic energy) may be applied to a generator and converted to electrical energy by the generator to stop the vehicle. The electric power generated at this time is used to charge the secondary battery. Japanese Patent Application Laid-Open No. 8-308025 (Patent Document 1) discloses an electric vehicle power supply control device relating to such vehicle control.

  The electric vehicle power supply control device includes a motor that operates as a vehicle drive source during acceleration and operates as a generator during deceleration, a first power storage unit, a second power storage unit capable of rapid charge / discharge with little power loss, A converter having a step-down side connected to the power storage means, a converter control device for controlling the operation of the converter, and an inverter having an AC side connected to the motor and a DC side connected to the first power storage means and the step-up side of the converter. An electric vehicle power supply control device that supplies power to the motor from the first power storage means and the second power storage means and regenerates power from the motor during deceleration, a current detection device that detects the magnitude and direction of the inverter DC current, and a converter current A current detection resistor that detects whether or not the vehicle is accelerating or regenerating according to the detection signal from the current detection device. At that time, when the inverter DC current is equal to or lower than a predetermined discharge current, the converter is turned off, and when it exceeds the predetermined discharge current, the converter is boosted to supply the excess from the second power storage means, During deceleration, the converter is turned off when the inverter DC current is equal to or less than a predetermined charging current, and the converter is stepped down so that when the inverter charging current exceeds the specified charging current, the excess current flows to the second power storage means.

According to this electric vehicle power supply control device, when power is supplied to the motor during vehicle acceleration, power is supplied only from the first power storage means if the required current is equal to or less than a predetermined discharge current predetermined for the first power storage means such as a battery. To do. When more current is required, the amount exceeding the specified discharge current is supplied from the second power storage means via the converter. As a result, the discharge current of the first power storage means is further leveled and charging from the second power storage means to the first power storage means does not occur even if the power required by the motor is reduced. Further, when regenerating electric power from the motor, if the DC current of the inverter, which is the regenerative current, is equal to or less than the specified charging current that is predetermined for the first power storage means, it flows only to the first power storage means. If it is more than that, the amount exceeding the specified charging current is passed through the converter to the second power storage means. As a result, the charging current to the first power storage means is further leveled, and even if the regenerative current is reduced, charging from the first power storage means to the second power storage means does not occur.
JP-A-8-308025

  However, the electric vehicle power supply control device disclosed in Patent Document 1 must include second power storage means such as a capacitor provided via a converter in addition to the first power storage means such as a battery. That is, two (two types) or more power storage mechanisms are required. For this reason, it cannot be applied to a vehicle equipped with only a battery. For this reason, in a vehicle equipped with only one power storage mechanism such as a battery or a capacitor (for example, a vehicle having only a battery), if the battery is in a fully charged state, the generator generates power when the engine is stopped. When the generated power is supplied to the battery, the battery is overcharged. This can cause the battery to deteriorate and shorten its life. In addition, current and voltage changes may increase instantaneously and exceed allowable values.

  The present invention has been made to solve the above-described problems, and its purpose is to generate electric power generated when the vehicle is stopped even in a vehicle equipped with only one power storage mechanism such as a battery or a capacitor. It is providing the control apparatus of the vehicle which can supply and charge to an electrical storage mechanism. Another object is to provide a vehicle control device that can sufficiently supply electric power for operating an electric device for driving the vehicle from a power storage mechanism.

  A vehicle control device according to a first aspect of the invention controls a vehicle that is driven by operating an electric device using electric power of a power storage mechanism. The control device includes a step-up / step-down unit for stepping up / down the electric power of the power storage mechanism and a control unit for controlling the step-up / step-down unit. When the step-up / step-down means is changed from the step-up operation to the step-down operation, the electric power stored in the step-up / step-down means is supplied to the power storage mechanism. The control means includes means for controlling the step-up / step-down means so as not to synchronize the timing when the electric power generated by operating the electric device is supplied to the power storage mechanism and the timing for changing to the step-down operation.

  According to the first invention, the voltage of the stored electric power, such as a secondary battery or a capacitor as a power storage mechanism, is boosted or lowered by a DC / DC converter or the like as a step-up / down means. This DC / DC converter has a capacitor called a smoothing capacitor that stores electric charge during boosting. When the boosting operation is switched to the step-down operation, the electric charge stored in the smoothing capacitor is released and returned to the power storage mechanism. When such a change of operation is performed and the power storage mechanism is in a fully charged state or a state close to a fully charged state, it becomes impossible to store the generated power by operating the generator, which is an electrical device. That is, charging may be prohibited because the power storage mechanism may be overcharged and may deteriorate the power storage mechanism, or the current and voltage may increase instantaneously and exceed allowable values. is there. In order to avoid such a situation, the control means includes a DC / DC converter so as not to synchronize the timing when the electric power generated by the generator is supplied to the power storage mechanism and the timing for changing to the step-down operation of the DC / DC converter. To control. For example, when power is generated by a generator or when there is a plan to generate power, switching to the step-down operation of the DC / DC converter is prohibited. In this way, the timing when the power generated by the generator is supplied to the power storage mechanism and the timing for changing to the step-down operation of the DC / DC converter do not overlap, and the power generated by the generator is supplied to the power storage mechanism. Is charged. As a result, it is possible to provide a vehicle control device that can supply electric power generated when the vehicle is stopped to a power storage mechanism even in a vehicle equipped with only one power storage mechanism such as a battery or a capacitor.

  In the vehicle control device according to the second invention, in addition to the configuration of the first invention, the time when the electric power generated by operating the electric device is supplied to the power storage mechanism is when the engine is stopped or the engine This is the time when the generator is operated by the engine and electric power is generated when the rotational speed decreases.

  According to the second invention, the vehicle is equipped with an engine as a drive source of the vehicle, the electric device is a generator, and the control means is configured to supply the electric power generated by the generator to the power storage mechanism, The DC / DC converter is controlled so as not to synchronize with the change timing to the step-down operation of the / DC converter. For example, since the generator is scheduled to generate power before the engine is stopped, switching to the step-down operation of the DC / DC converter is prohibited. Since the power generation time can be avoided from the change time to the step-down operation of the DC / DC converter, the power storage mechanism can be charged using the power generated by the generator.

  In the vehicle control apparatus according to the third invention, in addition to the configuration of the first or second invention, the step-up / step-down means is a DC / DC converter, and when the step-up operation is changed to the step-down operation, The electric power stored in the smoothing capacitor of the DC / DC converter is supplied to the power storage mechanism.

  According to the third aspect of the invention, when the DC / DC converter is changed from the step-up operation to the step-down operation, power (charge) is supplied from the smoothing capacitor to the power storage mechanism. Therefore, the power storage mechanism can be charged using the power generated by the generator.

  A vehicle control device according to a fourth aspect of the invention controls a vehicle that is driven by operating an electric device using the electric power of the power storage mechanism. The control device includes a step-up / step-down unit for stepping up / down the electric power of the power storage mechanism and a control unit for controlling the step-up / step-down unit. When the step-up / step-down means is changed from the step-down operation to the step-up operation, electric power stored in the step-up / step-down means is supplied from the power storage mechanism. The control means includes means for controlling the step-up / step-down means so as not to synchronize the timing when the electric power for operating the electric device is supplied from the power storage mechanism to the electric device and the timing for changing to the boosting operation.

  According to the fourth invention, the voltage of the stored electric power such as a secondary battery or a capacitor as a power storage mechanism is boosted or lowered by a DC / DC converter or the like as a step-up / down means. This DC / DC converter has a capacitor called a smoothing capacitor that stores electric charge during boosting. When the step-down operation is switched to the boosting operation, electric power for storing electric charge in the smoothing capacitor is supplied from the power storage mechanism. When such a change of operation is performed and the power storage mechanism is discharged, the motor, which is an electrical device, cannot be operated to drive the vehicle. In other words, there is a possibility that the power storage mechanism will be in an overdischarged state and the power storage mechanism may be deteriorated, or the change in current and voltage may increase instantaneously and exceed the allowable value. is there. In order to avoid such a situation, the control means controls the DC / DC converter so as not to synchronize the timing when the electric power is supplied from the power storage mechanism to the motor and the timing when the DC / DC converter is changed to the boosting operation. . For example, when the vehicle is driven by a motor or when the vehicle is scheduled to be driven by a motor, switching to the step-up operation of the DC / DC converter is prohibited. If it does in this way, the time when the electric power supplied to a motor is supplied from an electrical storage mechanism, and the change timing to the pressure | voltage rise operation of a DC / DC converter will not overlap, and sufficient electric power for a motor can be supplied from an electrical storage mechanism. As a result, it is possible to provide a vehicle control device that can sufficiently supply electric power for operating an electrical device for driving a vehicle even from a vehicle equipped with only one power storage mechanism such as a battery or a capacitor. Can do.

  In the vehicle control apparatus according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the vehicle is driven by the electric device when power for operating the electric device is supplied from the power storage mechanism to the electric device. When the electric device is activated and power is consumed.

  According to the fifth invention, the control means controls the DC / DC converter so as not to synchronize the timing when the electric power is supplied to the motor to the power storage mechanism and the timing when the DC / DC converter is boosted. For example, when the motor is driven to assist the engine, since the motor is scheduled to be discharged, switching to the boosting operation of the DC / DC converter is prohibited. Since the discharge time can be avoided from the change time to the step-up operation of the DC / DC converter, sufficient electric power can be supplied to the motor.

  In the vehicle control apparatus according to the sixth invention, in addition to the configuration of the fourth or fifth invention, the step-up / step-down means is a DC / DC converter, and when the step-down operation is changed to the step-up operation, The electric power stored in the smoothing capacitor of the DC / DC converter is supplied from the power storage mechanism.

  According to the sixth invention, when the DC / DC converter is changed from the step-down operation to the step-up operation, electric power (charge) is supplied from the power storage mechanism to the smoothing capacitor, but when the electric power is consumed by the motor Since such a change is not performed, sufficient electric power can be supplied to the motor.

  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.

  A control block diagram of a hybrid vehicle according to an embodiment of the present invention will be described with reference to FIG. The present invention is not limited to the hybrid vehicle shown in FIG. It may be a hybrid vehicle having another aspect. Further, it may be an electric vehicle or a fuel cell vehicle.

  The hybrid vehicle includes an internal combustion engine (hereinafter simply referred to as an engine) 120 such as a gasoline engine or a diesel engine, and a motor generator (MG) 140 as drive sources. In FIG. 1, for convenience of explanation, the motor generator 140 is expressed as a motor 140A and a generator 140B (or a motor generator 140B). However, depending on the traveling state of the hybrid vehicle, the motor 140A functions as a generator, The generator 140B functions as a motor.

  In addition to this, the hybrid vehicle transmits a power generated by the engine 120 and the motor generator 140 to the drive wheels 160, and a reduction gear 180 that transmits the drive of the drive wheels 160 to the engine 120 and the motor generator 140, and the engine 120. Power split mechanism (for example, planetary gear mechanism) 200 that distributes the generated power to two paths of drive wheel 160 and generator 140B, travel battery 220 that charges power for driving motor generator 140, and travel Inverter 240 that performs current control while converting the direct current of battery 220 and the alternating current of motor 140A and generator 140B, and a battery control unit (hereinafter referred to as a battery ECU (Electronic Control Unit)) that manages and controls the charge / discharge state of traveling battery 220 260) and En The engine ECU 280 for controlling the operation state of the engine 120, the MG_ECU 300 for controlling the motor generator 140, the battery ECU 260, the inverter 240, etc. according to the state of the hybrid vehicle, and the battery ECU 260, the engine ECU 280, the MG_ECU 300, etc. And HV_ECU 320 that controls the entire hybrid system so that the hybrid vehicle can operate most efficiently.

  In the present embodiment, boost converter 242 is provided between battery for traveling 220 and inverter 240. This is because the rated voltage of the traveling battery 220 is lower than the rated voltage of the motor 140A or the motor generator 140B, and therefore when the power is supplied from the traveling battery 220 to the motor 140A or the motor generator 140B, the boost converter 242 supplies the power. Boost the pressure. The step-up converter 242 includes a smoothing capacitor. When the step-up converter 242 is changed from the step-up operation to the step-down operation, the electric charge stored in the smoothing capacitor is supplied to the traveling battery 220.

  In FIG. 1, each ECU is configured separately, but may be configured as an ECU in which two or more ECUs are integrated (for example, MG_ECU 300 and HV_ECU 320, as shown by a dotted line in FIG. 1). An example is an integrated ECU).

  The power split mechanism 200 uses a planetary gear mechanism (planetary gear) in order to distribute the power of the engine 120 to both the drive wheel 160 and the motor generator 140B. By controlling the rotation speed of motor generator 140B, power split device 200 also functions as a continuously variable transmission. The rotational force of the engine 120 is input to the planetary carrier (C), which is transmitted to the motor generator 140B by the sun gear (S) and to the motor and the output shaft (drive wheel 160 side) by the ring gear (R). When the rotating engine 120 is stopped, since the engine 120 is rotating, the kinetic energy of this rotation is converted into electric energy by the motor generator 140B, and the rotational speed of the engine 120 is reduced.

  In a hybrid vehicle equipped with a hybrid system as shown in FIG. 1, the hybrid vehicle travels only by the motor 140 </ b> A of the motor generator 140 when the engine 120 is inefficient, such as when starting or running at a low speed. During normal travel, for example, the power split mechanism 200 divides the power of the engine 120 into two paths, and on the other hand, the drive wheels 160 are directly driven, and on the other hand, the generator 140B is driven to generate power. At this time, the motor 140A is driven by the generated electric power to assist driving of the driving wheels 160. Further, at the time of high speed traveling, electric power from the traveling battery 220 is further supplied to the motor 140A to increase the output of the motor 140A and to add driving force to the driving wheels 160. On the other hand, at the time of deceleration, motor 140 </ b> A driven by drive wheel 160 functions as a generator to perform regenerative power generation, and the collected power is stored in traveling battery 220. When the amount of charge of traveling battery 220 decreases and charging is particularly necessary, the output of engine 120 is increased to increase the amount of power generated by generator 140B to increase the amount of charge for traveling battery 220. Of course, control is performed to increase the drive amount of the engine 120 as necessary even during low-speed traveling. For example, it is necessary to charge the traveling battery 220 as described above, to drive an auxiliary machine such as an air conditioner, or to raise the temperature of the cooling water of the engine 120 to a predetermined temperature.

  The technical feature of the present embodiment is that, when there is an engine stop request for engine 120 or when engine 120 is in the stop process, motor generator 140B is used to convert the kinetic energy of engine 120 into electrical energy. And the traveling battery 220 is charged using the generated electric power. At this time, if the boost converter 242 enters the step-down operation from the step-up operation, the charge stored in the smoothing capacitor is supplied to the traveling battery 220. When the electric charge stored in the smoothing capacitor is supplied to the traveling battery 220 and the traveling battery 220 is charged to be in a fully charged state or nearly in a fully charged state, the electric power generated using the motor generator 140B is used for traveling. Battery 220 cannot be charged (becomes overcharged). Also, current and voltage changes may increase instantaneously and exceed allowable values. Therefore, in such a case, the change from the step-up operation to the step-down operation is prohibited so that power is not supplied from the smoothing capacitor of step-up converter 242 to battery for traveling 220.

  With reference to FIG. 2, the control structure of the engine stop process executed by MG_ECU 300 will be described.

  In step (hereinafter, step is abbreviated as S) 100, MG_ECU 300 determines whether engine 120 is in operation or not. This determination is made based on, for example, a signal detected by an engine speed sensor input from engine ECU 280 to MG_ECU 300 via HV_ECU 320. If engine 120 is in operation (YES in S100), the process proceeds to S110. Otherwise (NO in S100), this process ends.

  In S110, MG_ECU 300 determines whether there is an engine stop request for engine 120 or whether engine 120 is in a stop process. This determination is also made based on various signals input from engine ECU 280 to MG_ECU 300 via HV_ECU 320, similarly to the determination in S100. If there is an engine stop request for engine 120 or engine 120 is being stopped (YES in S110), the process proceeds to S120. If not (NO in S110), the process proceeds to S130.

  In S120, MG_ECU 300 turns off the step-down permission signal output to step-up converter 242. When this step-down permission signal is turned off, step-up converter 242 cannot enter the step-down operation, and traveling battery 220 is not charged by the charge stored in the smoothing capacitor.

  In S130, MG_ECU 300 turns on the step-down permission signal output to step-up converter 242. When the step-down permission signal is turned on, step-up converter 242 can enter a step-down operation. When the operation is changed to the step-down operation, the traveling battery 220 is charged by the electric charge stored in the smoothing capacitor.

  An operation of the vehicle according to the present embodiment based on the above-described structure and flowchart will be described.

  The driver of the hybrid vehicle sets the ignition key to the engine start position and gives an instruction to start the engine so that the engine 120 is in operation or the engine 120 is in operation in accordance with an instruction from the HV_ECU 320 (YES in S100). ). For example, when the engine 120 is stopped and the SOC (States Of Charge) of the battery for traveling 220 is lowered and needs to be charged while traveling only with the motor 140A, the engine 120 is operated and the engine 120 is operated. The engine 120 is in operation in accordance with an instruction from the HV_ECU 320 to rotate the generator 140B to generate electric power and charge the traveling battery 220.

If engine stop is requested or engine 120 is being stopped during operation of engine 120 (YES in S110), the step-down permission signal is turned off to step-up converter 242, and step-up converter 242 enters step-down operation. The electric charge stored in the smoothing capacitor is left as it is .

  As described above, according to the vehicle control apparatus of the present embodiment, in the hybrid vehicle, when the engine is stopped by generating power using the generator, only one power storage mechanism such as a battery or a capacitor is mounted. It is possible to provide a vehicle control device that can supply electric power generated when the vehicle is stopped to the power storage mechanism even in a vehicle that is not.

  Note that a mode opposite to the above-described mode is also conceivable. That is, if the timing at which generator 140B consumes power of battery for traveling 220 and the timing at which boost converter 242 is changed from the step-down operation to the step-up operation overlap, the battery from traveling battery 220 to the smoothing capacitor of boost converter 242 will overlap. Electric power is supplied, and electric power is supplied from the traveling battery 220 to the generator 140B. At this time, the step-up converter 242 is changed from the step-down operation to the step-up operation so that the overdischarge state does not occur and the current and voltage changes do not increase instantaneously and exceed the allowable values. Control to prohibit. In this way, it is possible to prevent overdischarge and a large change in current and voltage instantaneously.

  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.

It is a control block diagram of the hybrid vehicle which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the engine stop process performed by MG_ECU.

Explanation of symbols

  120 Engine, 140 Motor Generator, 140A Motor, 140B Generator, 160 Drive Wheel, 180 Reducer, 200 Power Dividing Mechanism, 220 Traveling Battery, 240 Inverter, 242 Boost Converter, 260 Battery ECU, 280 Engine ECU, 300 MG_ECU, 320 HV_ECU.

Claims (2)

A vehicle control device including a travel motor, a generator, an engine used in combination with the travel motor as a vehicle drive source, and a power storage mechanism for supplying power to the travel motor,
A step-up / step-down means for supplying electric power of the power storage mechanism to the traveling motor by a step-up operation, and supplying electric power generated by the generator to the power storage mechanism by a step-down operation ;
Control means for controlling the step-up / step-down means,
When the step-up / step-down means is changed from the step-up operation to the step-down operation, the electric power stored in the smoothing capacitor inside the step-up / step-down means is supplied to the power storage mechanism,
The control means includes a timing when electric power generated by the operation of the generator by the engine is supplied to the power storage mechanism when the engine is stopped or when the rotational speed of the engine is reduced, and the step-up / step-down means Controlling the step-up / step-down means so as not to synchronize the change timing from the step-up operation to the step-down operation ,
When the engine is in operation, and when the engine is requested to stop or when the engine is being stopped, the control means is configured to prohibit the step-down operation. A vehicle control device for controlling the pressure means . The step-up / step-down means is a DC / DC converter, and when the step-up operation is changed to the step-down operation, the electric power stored in the smoothing capacitor inside the DC / DC converter is supplied to the power storage mechanism. The vehicle control device according to claim 1.

Images