JP2015196455A - Hybrid electric vehicle control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid electric vehicle control system capable of preventing the excessive output voltage from a step-up converter even at a time of slip detection and preventing the degradation of engine startability.SOLUTION: A control system 12 of a hybrid electric vehicle 10 comprises: an engine 20; a second MG 24 serving as a travel motor; a first MG 22 serving as a generator; and an ECU 32 serving as a control unit that controls a step-up operation performed by a step-up converter 46 connected between a battery 28 serving as a power storage unit, and the first and second MG 22 and 24. The ECU 32 controls the step-up converter 46 to increase a target output voltage of the step-up converter 46 from an output voltage before slip detection or to keep the target output voltage equal to the output voltage before the slip detection if the slip of driving wheels 18 is detected and the hybrid electric vehicle 10 is in an EV travel mode for allowing the vehicle 10 to travel by driving the second MG 24 while stopping the engine 20.

Description

  The present invention relates to a control system for a hybrid vehicle, and more particularly to control of a boost converter when a slip of a drive wheel is detected.

  In a hybrid vehicle including an engine and a travel motor as a vehicle drive source, the power supply voltage may be boosted by a boost converter and output to the travel motor side. In this hybrid vehicle, when the drive wheel slips, a large amount of power is consumed by the travel motor. However, when the slip is eliminated and the drive wheel grips, the speed of the travel motor suddenly increases. Since the voltage decreases, the output voltage on the high voltage side of the boost converter may become excessive.

  In Patent Document 1, in order to prevent the output voltage of the boost converter from becoming excessive, slippage of the drive wheel is detected, and when the motor current is disturbed, the output is connected to the output side of the boost converter. Further, it is described that the control mode is improved by switching the control mode of the inverter and the control is performed to reduce the target output voltage on the high voltage side of the boost converter.

JP 2007-20383 A

  In the case of the control described in Patent Document 1, it is difficult to rapidly reduce the high-voltage side output voltage due to a small capacity of the capacitor connected to the boost converter. If the high-voltage side output voltage becomes excessive, an overvoltage may occur in the inverter. On the other hand, as a means for preventing the generation of an excessively high output voltage, it is conceivable that the target output voltage on the high voltage side is lowered early in preparation for the transition to the next grip state when a slip is detected. However, in this case, when the power split mechanism is connected between the engine, the traveling motor, and the generator, the rotational speed of the generator for starting the engine increases as the rotational speed of the traveling motor increases due to slip. In addition, when the high-voltage side voltage VH further decreases, engine startability may decrease.

  An object of the present invention is to provide a control system for a hybrid vehicle that can prevent an output voltage of a boost converter from becoming excessive even when a slip is detected, and can prevent a decrease in engine startability.

  A control system for a hybrid vehicle according to the present invention includes an engine, a travel motor connected to a power storage unit, a power generation function connected to the power storage unit and driven by the engine to generate power, and a motor function to start the engine And a control device that controls the boosting operation of the boost converter connected between the power storage unit, the travel motor, and the generator according to the traveling state of the vehicle, and in an engine stopped state The engine, the traveling motor, and the generator are connected so that the rotational speed of the generator increases when the rotational speed of the traveling motor increases, and at least one of the engine and the traveling motor is connected. A control system for a hybrid vehicle that travels by driving a drive wheel as a drive source, wherein the control device detects a slip of the drive wheel. In this case, and when the vehicle is traveling by EV while driving the traveling motor while the engine is stopped, whether the target output voltage of the boost converter is increased before the detection of the slip Or the boost converter is controlled so as to be maintained at the same size.

  In the hybrid vehicle control system according to the present invention, preferably, the control device decreases the target output voltage of the boost converter when the slip is detected and when the EV traveling is not being performed.

  According to the hybrid vehicle control system of the present invention, it is possible to prevent the output voltage of the boost converter from becoming excessive even when slip is detected, and to prevent a decrease in engine startability.

It is a lineblock diagram showing a hybrid vehicle carrying a control system of an embodiment of the present invention. It is a figure which shows the state which the drive wheel slipped in the engine stop state, Comprising: It is a collinear diagram which shows the relationship between the rotation speed of two motor generators and an engine. It is a flowchart which shows the method of controlling a boost converter using the control system of embodiment of this invention. In embodiment of this invention, it is a figure which shows the operation | movement waveform (a) for demonstrating the target output voltage of the step-up converter at the time of slip detection, the slip state (b) of a drive wheel, and the grip state (c). In the embodiment of the present invention, it is an operation waveform diagram for explaining operation of the vehicle at the time of slip detection. It is a flowchart which shows another example of the method of controlling a boost converter using the control system of embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a step-up / step-down converter having a step-up / step-down function will be described as a step-up converter. In the following description, similar elements are denoted by the same reference numerals in all drawings.

  FIG. 1 shows a schematic configuration of a hybrid vehicle equipped with a control system according to an embodiment of the present invention. The hybrid vehicle 10 includes a control system 12, a speed reducer 14, and drive wheels (for example, front wheels) 18 connected to a drive shaft 16. The control system 12 includes an engine 20, a first motor generator 22, a second motor generator 24, a power split mechanism 25, a PCU 26, a battery 28 as a power storage unit, and an ECU 32 as a control device. The hybrid vehicle 10 travels using at least one of the engine 20 and the second motor generator 24 as a drive source. Hereinafter, the first motor generator 22 is described as a first MG 22, and the second motor generator 24 is described as a second MG 24.

  The engine 20 is controlled by a control signal Si1 from the ECU 32. An engine speed sensor 34 that detects the speed Ne of the crankshaft is attached to the engine 20. In this specification, “the number of rotations” means the number of rotations per unit time, for example, every minute.

  The first MG 22 is a three-phase synchronous generator that is connected to the battery 28 and has a power generation function that is basically driven by the engine 20 to generate power. The first MG 22 also has a motor function for starting the engine 20. When first MG 22 is used as a generator, at least part of the torque from engine 20 is transmitted to the rotating shaft of first MG 22 via power split mechanism 25 described later. The electric power generated in the first MG 22 is supplied to the battery 28 via the PCU 26, and the battery 28 is charged. A first rotation sensor 36 that detects the rotation angle or the rotation speed Nw1 of the rotation shaft of the first MG 22 is attached to the first MG 22.

  The second MG 24 is a three-phase synchronous motor that is connected to the battery 28, is basically used as a travel motor, and is driven by electric power supplied from the battery 28. By driving the second MG 24, the driving wheels 18 are driven to generate a driving force of the vehicle. The second MG 24 also has a function as a power regeneration generator when regenerative braking is performed during vehicle deceleration. The electric power generated in the second MG 24 is also supplied to the battery 28 via the PCU 26, and the battery 28 is charged. A second rotation sensor 38 that detects the rotation angle or the rotation speed Nw2 of the rotation shaft of the second MG 24 is attached to the second MG 24. An induction motor or another electric motor may be used as the first MG and the second MG.

  Signals representing detection values Ne, Nw1, and Nw2 of the engine speed sensor 34, the first rotation sensor 36, and the second rotation sensor 38 are transmitted to the ECU 32.

  The power split mechanism 25 is formed by a planetary gear mechanism. For example, the planetary gear mechanism includes a sun gear, a plurality of pinion gears, a carrier, and a ring gear, and the sun gear is coupled to the end of the hollow rotation shaft of the first MG 22. The plurality of pinion gears mesh with both the ring gear and the sun gear, and are connected to the drive shaft of the engine 20 via a carrier. Each pinion gear is connected to the end portion of the carrier so as to be capable of revolution and rotation with the center axis of the carrier as the center of rotation. The ring gear is connected to the output shaft 40, and the output shaft 40 is coupled to the rotation shaft of the second MG 24. The output shaft 40 may be coupled to the rotation shaft of the second MG 24 via a speed reduction mechanism including another planetary gear mechanism (not shown). The output shaft 40 is connected to the drive shaft 16 connected to the drive wheels 18 via the speed reducer 14 shown in FIG. Power split device 25 splits the power from engine 20 into a route to output shaft 40 and a route to first MG 22.

  Thus, power split device 25 connects engine 20, first MG 22, and second MG 24 so that the rotation speed of first MG 22 also increases when the rotation speed of second MG 24 increases while the engine is stopped. The ring gear of power split device 25 may be connected to first MG 22 and the sun gear may be connected to second MG 24.

  FIG. 2 is a diagram illustrating a state in which the drive wheel 18 slips in a state where the engine is stopped, and is a collinear diagram illustrating a relationship between the two first MGs 22, the second MG 24, and the rotational speed of the engine 20. Since the engine 20, the first MG 22 and the second MG 24 are connected by a planetary gear mechanism, the rotational speeds of the first MG 22, the engine 20 and the second MG 24 are connected in a straight line as shown in FIG. In the nomogram, the ratio of the lengths between the rotation speeds of the first MG 22, the engine 20, and the second MG 24 is determined from the ratio of the number of teeth of the ring gear and the sun gear.

  For example, when the drive wheel 18 slips and the rotation speed of the second MG 24 connected to the ring gear increases in the positive direction (+ direction) as indicated by an arrow R1 in FIG. 2, the first MG 22 connected to the sun gear. As shown by the arrow R2, the number of rotations greatly changes in the negative direction (− direction). In this case, the engine 20 can be started by generating a torque in the first MG 22 in the positive direction. In this case, a large voltage corresponding to the rotation speed of the first MG 22 needs to be applied to the first MG 22.

  In this example, as will be described later, when the slip of the drive wheel 18 is detected, the output voltage VH may be lowered in order to prevent the output voltage VH of the boost converter 46 from becoming excessive. . In this case, since the first inverter 42 connected to the first MG 22 is also connected to the boost converter 46, the voltage applied to the first MG 22 is insufficient, and the startability of the engine 20 may be reduced. In this example, in order to prevent such inconvenience, as described later, when the slip is detected during EV traveling in which the second MG 24 is driven to drive the vehicle while the engine is stopped, the boost converter 46 outputs the slip. The boost converter 46 is controlled by the ECU 32 so that the boosted voltage is maintained or increased at the same level as before the slip detection.

  The PCU 26 is connected between the first MG 22 and the second MG 24 and the battery 28. PCU 26 includes a first inverter 42 and a second inverter 44, and a boost converter 46. Boost converter 46 is controlled by a control signal Si2 from ECU 32, and each inverter 42, 44 is controlled by a control signal Si3 from ECU 32. Boost converter 46 has two switching elements connected in series, two diodes connected in parallel so that a reverse current flows to each switching element, and one end connected between each switching element. Including reactors. A transistor such as an IGBT is used as the switching element. Boost converter 46 is connected between battery 28 and each of inverters 42, 44, and when controlled by ECU 32 with a boost command, boosts the DC voltage input from battery 28 to each inverter 42, 44. It has a function of outputting a boosted voltage. Boost converter 46 also has a function of stepping down a DC voltage on the output side (voltage VH side) and outputting a DC voltage to battery 28 when controlled by ECU 32 with a step-down command. Thereby, the battery 28 is charged.

  First inverter 42 converts the DC voltage input from boost converter 46 into an AC voltage, and outputs the AC voltage to first MG 22 to drive first MG 22. The first inverter 42 also has a function of converting the AC voltage obtained by the power generation into a DC voltage and outputting the DC voltage to the boost converter 46 when the first MG 22 generates power as the engine 20 is driven.

  The second inverter 44 converts the DC voltage input from the boost converter 46 into an AC voltage, supplies the AC voltage to the second MG 24, and drives the second MG 24. Second inverter 44 also has a function of converting the AC voltage generated by second MG 24 into a DC voltage and outputting the DC voltage to boost converter 46 during regenerative braking of hybrid vehicle 10.

  The first inverter 42 and the second inverter 44 include switching elements respectively provided in the upper arm and the lower arm of each phase of U, V, and W, and switching of each switching element is controlled by a control signal Si2 from the ECU 32. Is done. The input terminal of each phase of the first MG 22 is connected between the upper arm and the lower arm of each phase of U, V, and W of the first inverter 42 by a power line. Current sensors 48u and 48v for detecting motor current are attached to the V-phase power line. Although no current sensor is attached to the W-phase power line, the total current of each phase is zero in the three-phase AC, so the W-phase current value is calculated from the U-phase and V-phase current values. It is done. Similarly, current sensors 49u and 49v are attached to the U-phase and V-phase power lines connecting the second inverter 44 and the second MG 24. Signals representing detection values of the current sensors 48u, 48v, 49u, 49v are transmitted to the ECU 32.

  The battery 28 is a nickel metal hydride battery or a lithium ion battery or other type of secondary battery. A capacitor may be used instead of the battery. A system relay (not shown) is provided between the battery 28 and the boost converter 46, and the system relay is controlled to be turned on and off by the ECU 32. A smoothing capacitor may be connected between the boost converter 46 and the battery 28 and between the boost converter 46 and each of the inverters 42 and 44.

  Voltage sensor 50 detects low voltage VL of boost converter 46 and transmits a signal representing voltage VL to ECU 32. Voltage sensor 52 detects high voltage side voltage VH of boost converter 46 and transmits a signal representing high voltage side voltage VH to ECU 32.

  The accelerator position sensor 54 detects the accelerator position AP of the accelerator pedal, and transmits a signal representing the accelerator position AP to the ECU 32. The drive wheel rotation sensor 56 detects the rotation angle or the rotation speed Hs of the drive wheel 18 and transmits a signal representing the detection value Hs to the ECU 32. The ECU 32 calculates an estimated vehicle speed based on the detection value Hs. The ECU 32 may calculate the estimated vehicle speed based on the detected value of the rotation angle or the rotation speed Nw2 of the second MG 24. The vehicle speed sensor 58 detects the actual vehicle speed of the vehicle. For example, the vehicle speed sensor 58 may be configured to calculate the vehicle speed from a detection value of a rotation sensor that detects a rotation angle or a rotation speed Vs of a driven wheel (for example, a rear wheel) (not shown). A signal representing the detected value Vs of the vehicle speed sensor 58 is transmitted to the ECU 32.

  The ECU 32 includes a microcomputer having a CPU and a memory. In the illustrated example, only one ECU 32 is illustrated as the ECU 32, but the ECU 32 may be appropriately divided into a plurality of components and connected to each other by a signal cable. The ECU 32 includes a converter control unit 60 that controls the operation of the boost converter 46 and an inverter control unit 62 that controls the operations of the inverters 42 and 44. The ECU 32 also includes an EV travel determination unit 66 and a slip detection unit 68, which will be described later.

  The ECU 32 calculates the vehicle target torque Tr * and the engine target output Pe * based on the accelerator position AP or the vehicle speed and the accelerator position AP during the travel drive control, and uses the target rotation of the engine 20 from a preset map. The number Ne * and the target torque Te * are calculated. The ECU 32 calculates the target rotational speed Nw1 * and target torque Tr1 * of the first MG22 and the target torque Tr2 * of the second MG24 from the target rotational speed Ne *, the rotational speed Nw2 of the second MG24, and the rotational speed Nw1 of the first MG22. To do. Such target rotational speed Ne *, target torque Te *, target rotational speed Nw1 *, target torque Tr1 * and target torque Tr * are stored in a storage unit (not shown) based on the accelerator position AP or the accelerator position AP and the vehicle speed. You may calculate from the map memorize | stored beforehand.

  The ECU 32 controls the engine 20 with the control signal Si1 so that the calculated target rotational speed Ne * and target torque Te * of the engine 20 are obtained. In addition, the ECU 32 controls the control signal by the converter control unit 60 and the inverter control unit 62 so that the calculated target rotational speed Nw1 * and target torque Tr1 * of the first MG 22 and target torque Tr * of the second MG 24 are obtained. The boost converter 46 and the inverters 42 and 44 are controlled by Si2 and Si3. The inverter control unit 62 controls the inverters 42 and 44 while switching the control mode in accordance with the motor rotation state or the vehicle running state as will be described later.

  The ECU 32 calculates an SOC (State Of Charge) that is a charge amount of the battery 28 based on a detection value from one or both of a battery current sensor and a voltage sensor 50 (not shown). The calculated value of the SOC is used for controlling switching between the EV mode and the HV mode, which will be described later.

  Further, the ECU 32 controls the engine 20, the first MG 22 and the second MG 24 so that the vehicle travels while performing mode switching between the EV mode which is an EV travel mode and the HV mode. The “EV mode” is a mode in which the second MG 24 is driven and the vehicle travels using the second MG 24 as a drive source when the engine is stopped. The “HV mode” is a mode in which at least the engine 20 is driven and the vehicle is driven to travel. In this case, the first MG 22 generates power by driving the engine 20. Switching between the EV mode and the HV mode is performed depending on whether a predetermined condition set in advance is satisfied. For example, switching to the HV mode is performed when the calculated value of the SOC is equal to or lower than a predetermined lower limit value during execution of the EV mode. During execution of the HV mode, the driver operates the EV travel instruction unit 69 shown in FIG. 1 and is switched to the EV mode on condition that a predetermined EV mode precondition is satisfied when the EV mode is selected. In addition, during execution of the HV mode, the mode is switched to the EV mode also when the calculated value of the SOC exceeds a predetermined upper limit value. The EV traveling instruction unit 69 is, for example, a push button or a switch that instructs the EV mode.

  The EV travel determination unit 66 determines whether or not the current vehicle travel mode is the EV mode. The slip detection unit 68 detects whether or not the current vehicle running state causes the drive wheel 18 to slip.

  The slip detection unit 68 detects the slip based on the slip relationship value which is the deviation between the rotation speed of the drive shaft 16 or the time change rate of the rotation speed of the drive shaft 16 or the rotation speed of the drive wheel 18 and the rotation speed of the driven wheel. When the relationship value is equal to or greater than a preset threshold value, it may be detected that the vehicle is in the slip state. The detection value of the drive wheel rotation sensor 56 may be used for detecting the rotation speed of the drive wheel 18.

  As shown in FIG. 4B to be described later, when there is a convex portion 72 on the road surface 70 on which the vehicle travels, the driving wheel 18 rides on the convex portion 72, so that the road surface resistance is extremely reduced and the driving wheel 18 Almost idles and the rotation speed increases rapidly. This state is a slip state. After the slip, as shown in FIG. 4C, when the driving wheel 18 comes off the convex portion 72 and contacts the road surface 70, the slip is eliminated and a grip state is obtained.

  Converter control unit 60 also has a function of controlling the boosting operation of boost converter 46 in accordance with the current running state of the vehicle. More specifically, the converter control unit 60 is in the case where the slip is detected by the slip detection unit 68 and when “not traveling in the EV mode”, that is, “in traveling in the HV mode”. The boost converter 46 is controlled so as to lower the target output voltage V1 of the boost converter 46.

  In addition, when the slip is detected and “when traveling in the EV mode”, converter control unit 60 determines whether target output voltage V1 of boost converter 46 is increased or not before the slip detection. Or a target voltage rise maintaining module 74 that controls the boost converter 46 so that it is maintained at the same magnitude. Thereby, it is possible to prevent the output voltage of boost converter 46 from becoming excessive even when slip is detected, and to prevent the startability of engine 20 from being deteriorated. This will be described later.

  The inverter control unit 62 functions to control the inverters 42 and 44 by switching between three control modes, that is, a sine wave PWM control mode P1, an overmodulation control mode P2, and a rectangular wave control mode P3, according to the motor rotation state. Have

  The characteristics of the three control modes can be expressed by “modulation rate E”, which is a ratio of the motor required voltage to the high-voltage side voltage VH as the system voltage. The required motor voltage is determined from the calculated value including the torque command value, and is the effective value J of the line voltage required for the first MG 22 or the second MG 24. As a result, the modulation rate E becomes (J / VH).

  In the sine wave PWM control mode P1, the ON / OFF duty ratio of the switching element is controlled so that the fundamental wave component becomes a sine wave within a predetermined period. With this control, the amplitude of the fundamental component can be increased to 0.61 times the system voltage in the PWM control mode. In this case, the modulation rate E is 0.61.

  In the overmodulation control mode P2, the PWW control mode similar to the sine wave PWM control mode is performed by reducing the amplitude of the carrier wave. When the fundamental wave component is distorted by this control, the modulation factor E can be increased to a range of 0.61 to 0.78.

  In the rectangular wave control mode P3, one pulse of the rectangular wave having a ratio of ON / OFF of the switching element of 1: 1 in a predetermined period is applied to the first MG 22 or the second MG 24. As a result, the modulation factor E can be increased to 0.78.

  Switching between the three control modes can be performed according to the motor speed of the first MG 22 or the second MG 24, for example. In this case, the inverter control unit 62 selects the sine wave PWM control mode P1 capable of smooth rotation in the region where the motor rotation speed is low, according to the detection value of the rotation sensor 36 (or 38), and the motor rotation speed is Mode switching is performed so that the overmodulation control mode P2 and the rectangular wave control mode P3 are shifted in order in accordance with the increase. The inverter control unit 62 performs mode switching so that the control mode is switched in order when the motor rotation speed decreases.

  The inverter control unit 62 also has a function of performing emergency switching for switching between the rectangular wave control mode P3 and the overmodulation control mode P2 in accordance with the traveling state of the vehicle. “Emergency switching” refers to an overmodulation control mode from the rectangular wave control mode P3 when slip and grip occur during the execution of the rectangular wave control mode P3 and the motor current of the second MG 24 is disturbed to disturb the motor rotation. Further, switching to P2 and switching from the overmodulation control mode P2 to the sine wave PWM control mode P1.

  For example, the inverter control unit 62 calculates the d-axis current Id and the q-axis current Iq on the dq-axis plane from the detected values of the current sensors 48u and 48v and the detected value of the rotation angle of the second MG 24. The inverter control unit 62 determines whether or not the emergency switching condition is satisfied depending on whether or not the d-axis current Id exceeds a threshold value of the q-axis current Iq set in advance in the rectangular wave control mode P3. Here, the dq-axis plane is for defining the operating point of the second MG 24 with the d-axis and the q-axis orthogonal to each other. The d-axis current Id is a current component in the magnetic pole direction of the rotor forming the second MG 24, and the q-axis current Iq is a current component in a direction orthogonal to the magnetic pole direction of the rotor. When the emergency switching condition is satisfied, switching from the rectangular wave control mode P3 to the overmodulation control control mode P2 is performed. When the vehicle is in a slip state, the output voltage VH is reduced by a sharp increase in power consumption of the inverter 42, and the output side of the boost converter 46 is reduced by shifting from the slip state to the grip state and reducing the motor power consumption. An excessive energy state occurs, and the output voltage VH of the boost converter 46 increases. In this case, the q-axis current Iq of the motor current flowing from the second inverter 44 to the second MG 24 exceeds the threshold value. Then, since the emergency switching condition is satisfied at time t2A in FIG. 4 (A3) described later, the control mode is switched from the rectangular wave control mode P3 to the overmodulation control mode P2. As a result, the control is switched to a control with good responsiveness in an emergency in which the variation range of the rotation speed of the second MG 24 is large, so that control breakdown can be prevented.

  FIG. 3 is a flowchart showing a method for controlling the boosting of the boosting converter 46 using the control system 12 of the present embodiment. FIG. 4 shows an operation waveform (a) for explaining the target output voltage V1 of the boost converter 46 at the time of slip detection, a slip state (b) and a grip state (c) of the drive wheel 18 in this embodiment. Show.

  The ECU 32 first determines whether or not a slip is detected by the slip detection unit 68 (S10), and if a slip is detected, the ECU 32 determines whether or not the EV traveling is being performed by the EV traveling determination unit 66 (S12). ). For example, when it is detected that the slip state shown in FIG. 4B is reached at time t1 in FIG. 4A, the rotational speed Nw2 of the second MG 24 rapidly increases as shown in FIG. 4A1.

  In S12 of FIG. 3, in the case of “not running in EV”, that is, in the case of “running in HV” while the engine 20 is operating, the converter control unit 60, as shown in (A4) of FIG. The target output voltage V1 of 46 is reduced by a preset voltage α from the current target value V0, and the boost converter 46 is controlled as V1 = V0−α.

  On the other hand, in the case of “EV running” in S12 of FIG. 3, the converter control unit 60 determines that the target output voltage V1 of the boost converter 46 is the same as the current target output voltage as shown in (A5) of FIG. The step-up converter 46 is controlled so as to be maintained at a magnitude (B1) or to be increased at a predetermined rate from the current target output voltage (B2). In S12, it is set in advance whether the target output voltage V1 is maintained or increased. Note that the target output voltage V1 may be maintained when the target output voltage currently reaches the system maximum voltage V0 (for example, 650 V) in S12, and may be increased at a predetermined rate otherwise. “System maximum voltage” is an upper limit of a target output voltage set in advance from the viewpoint of component protection. The “predetermined rate” is a predetermined ratio or a predetermined amount of a voltage set in advance to prevent overcurrent to the inverters 42 and 44.

  In addition, when slip detection is not performed by S10 of FIG. 3, it is determined whether it is within predetermined time after slip transfer from slip detection. For example, when the predetermined time has not elapsed since the slip detection unit 68 no longer detects the slip, the process proceeds to S12. As a result, when the output voltage of boost converter 46 is still high during gripping and not during EV traveling, target output voltage V1 is decreased in S18.

  When the time after the slip detection from the slip detection in S14 exceeds the predetermined time, the boost converter 46 determines a preset map from the target rotational speed and target torque of the first MG 22 and the target torque and rotational speed of the second MG 24. Alternatively, the boost control which is the “normal boost” of the boost converter 46 is performed with the target output voltage V1 calculated using the relational expression. Also in this case, when the target output voltage V1 is increased, the target output voltage V1 is increased at a predetermined rate as in the case described in S16. When the processes of S16, S18, and S20 are completed, the process returns to S10.

  FIG. 4 also shows that the control mode is switched from the rectangular wave control mode P3 to the overmodulation control mode P2 at time t2A when the slip state shifts to the grip state.

  According to the control system 12, the target output voltage V1 of the boost converter 46 is increased or the same as that before the detection of the slip when the slip is detected and the EV is running. Maintained in size. For this reason, when the engine 20 is started using the first MG 22 and shifts to HV running, the input voltage of the first inverter 42 that drives the first MG 22 can be increased, so that the startability of the engine 20 is reduced even when slip detection is detected. Can be prevented.

  For example, when a slip is detected during EV travel, if the calculated SOC value is equal to or lower than a predetermined lower limit value, or if the EV mode selection is canceled by operating the EV travel instruction unit 69, slip occurrence occurs. The start of the engine 20 using the first MG 22 may occur at the same timing. In this case, in this example, since the input voltage of the first inverter 42 that drives the first MG 22 can be increased, the startability of the engine 20 can be prevented from being deteriorated.

  FIG. 5 is an operation waveform diagram for explaining the operation of the vehicle at the time of slip detection in the present embodiment. The input voltage of the first inverter 42 is determined by the output voltage VH of the boost converter 46. On the other hand, when a slip is detected during EV travel, for example, when the target output voltage V1 is constant at 650 V as indicated by W1 in FIG. 5 (A4, A5), an output is indicated as indicated by W2 in (A6). The voltage VH changes. Specifically, when the rotational speed Nw2 of the second MG 24 suddenly increases due to slip at time t1 (A1) and the torque of the second MG 24 is controlled to be constant, the power consumption Pm (A7) of the second MG 24 rapidly increases. . In this case, the power consumption of the second inverter 44 also increases, so the output voltage VH of the boost converter 46 decreases. The converter control unit 60 controls the boost converter 46 so as to recover the decrease in the output voltage VH, so that the output voltage VH once decreased returns to 650 V again. When the state shifts to the grip state at time t2, the rotation speed Nw2 of the second MG 24 rapidly decreases, so the power consumption Pm of the second MG 24 also decreases. As a result, the output side of boost converter 46 becomes excessive in energy, and output voltage VH exceeds 650 V from time t2 to t2A. In this case, the amount of power (Pm−Pg) obtained by subtracting the power generation amount Pg of the first MG 22 indicated by (A8) from the power consumption Pm of the second MG 24 indicated by (A7) and passing through the boost converter 46 is (A9 W3 shown in FIG. In this case, since Pg = 0 when the engine is stopped, W3 becomes relatively large in the power running state, and the power returned to the battery 28 is small or not generated. For this reason, the excessive energy state on the output side of boost converter 46 is alleviated and the increase in output voltage VH can be suppressed, so that output voltage VH can be prevented from becoming excessive. Therefore, as indicated by W2 in (A6), since the output voltage VH during EV traveling does not exceed the VH upper limit value set in advance from the viewpoint of component protection, overvoltage of each inverter 42, 44 can be prevented. During such EV traveling, it is less necessary to lower the output voltage VH than in the case of HV traveling described later.

  On the other hand, when the rotation speed of the second MG 24 increases in the slip state, the rotation speed of the first MG 22 greatly changes in the negative direction due to the relationship between the first MG 22 and the second MG 24 shown in FIG. In this case, the relationship of the upper limit of torque according to the rotation speed of the first MG 22 changes according to the output voltage VH, and the higher the output voltage VH, the more limited the torque may not be. In the case of this example, even when slip detection is performed during EV travel, the output voltage VH of the boost converter 46 becomes higher than W5 (A6) during HV travel, which will be described later, between times t1 and t2. For this reason, since the torque of 1st MG22 can be made high, the fall of the engine startability using 1st MG22 can be prevented.

  On the other hand, when slip is detected during HV traveling, the target output voltage V1 decreases from 650 V to 600 V, for example, as indicated by W4 in FIG. 5 (A4, A5), and output as indicated by W5 in (A6). The voltage VH changes. In this case, as in the case of the EV traveling, the rotation speed of the second MG 24 rapidly increases due to the slip, and the power consumption of the second MG 24 rapidly increases. In this case, the output voltage VH increases when shifting to the grip state at time t2.

  Further, since the first MG 22 generates power by driving the engine, the power amount (Pm−Pg) obtained by subtracting the power generation amount Pg of the first MG 22 from the power consumption Pm of the second MG 24 changes as indicated by W6 in (A9), and from the power running The power is reduced so as to shift to regeneration, and the power returned to the battery 28 is increased. However, in the case of this example, the output voltage VH shifts lower than in the case of EV traveling after the time t1 due to the detection of slip, so that the upper limit of the output voltage VH may reach the VH upper limit value even when shifting to the grip state. Therefore, overvoltage of each inverter 42, 44 can be prevented.

  FIG. 6 is a flowchart showing another example of a method for controlling the boosting of the boosting converter 46 using the control system 12 according to the embodiment of the present invention. In another example of FIG. 6, when slip is detected in S30 and S32 and it is determined that the vehicle is traveling in EV, the target output voltage V1 of the boost converter 46 is set to a preset system maximum voltage V0 (for example, 650 V). Boost converter 46 is controlled to increase or maintain system maximum voltage V0. The processing from S30 to S34 and the processing from S38 to S40 in FIG. 7 are the same as the processing from S10 to S14 and the processing from S18 to S20 in FIG.

  According to the above configuration, referring to FIG. 4 (A5), even when the target output voltage V1 of the boost converter 46 is lower than the system maximum voltage V0 (B2) before slip detection during EV traveling, slip detection is performed. Can quickly increase the target output voltage V1 to the system maximum voltage V0 as indicated by an arrow β. In the case of the configuration shown in FIGS. 1 to 5 above, during EV traveling, the target output voltage V1 before slip detection is obtained from the rotation speed and torque of the second MG 24 in the same manner as the normal boosting in S20 of FIG. Since it is determined on the way, the target output voltage V1 may be a low voltage (for example, 500V). In this case, even when the target output voltage V1 is increased by detecting the slip, the increase of the target output voltage V1 may be slow because the increase is limited at a predetermined rate. Such a problem can be prevented in the configuration of this example. For this reason, the engine startability at the time of slip detection can be improved. Other configurations and operations are the same as those in FIGS. 1 to 5.

  In each of the above examples, even when EV travel is not selected by the EV travel instructing unit 69 as “EV travel”, it is a case of EV travel including switching from the HV travel mode due to an increase in SOC, and slip detection. In the above case, the case where the target output voltage of the boost converter is increased or maintained at the same level as before the slip detection has been described. However, it is limited to the case where EV traveling is selected by the EV traveling instruction unit 69, and in the case of slip detection, the target output voltage of the boost converter is increased or equal to that before slip detection. It may be maintained.

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 12 Control system, 14 Reducer, 16 Drive shaft, 18 Drive wheel, 20 Engine, 22 1st motor generator (1st MG), 24 2nd motor generator (2nd MG), 25 Power split mechanism, 26 PCU , 28 battery, 32 ECU, 34 engine speed sensor, 36 first rotation sensor, 38 second rotation sensor, 40 output shaft, 42 first inverter, 44 second inverter, 46 boost converter, 48u, 48v, 49u, 49v Current sensor, 50, 52 Voltage sensor, 54 Accelerator position sensor, 56 Drive wheel rotation sensor, 58 Vehicle speed sensor, 60 Converter control unit, 62 Inverter control unit, 66 EV travel determination unit, 68 Slip detection unit, 69 EV travel instruction unit , 70 Road surface, 72 Convex, 74 Target power Pressure rise maintenance module.

Claims (1)

Engine,
A travel motor connected to the power storage unit;
A power generator connected to the power storage unit and driven by the engine to generate electric power, and a motor function to start the engine;
A control device for controlling a boosting operation of a boosting converter connected between the power storage unit, the traveling motor, and the generator according to a traveling state of a vehicle;
The engine, the traveling motor, and the generator are connected so that the rotational speed of the generator increases when the rotational speed of the traveling motor increases when the engine is stopped, and the engine and the traveling motor are connected. A control system for a hybrid vehicle that travels by driving a drive wheel using at least one of the drive source,
When the slip of the driving wheel is detected, and when the vehicle is traveling in EV by driving the travel motor while the engine is stopped, the control device detects the slip before the slip is detected. On the other hand, a control system for a hybrid vehicle that controls the boost converter so that a target output voltage of the boost converter is increased or maintained at the same level.

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