Hybrid vehicle control device

Abstract

To suppress a situation that desired torque cannot be outputted to a driving shaft, while suppressing a vehicle from vibrating.SOLUTION: When a vehicle speed is below or equal to a predetermined vehicle speed, temporary output power of a first motor is set so that the power is constant in a range of a hysteresis width with power which should be outputted from the first motor as a center, and a second motor is controlled so that the second motor is driven in a range of power limit values of the second motor based on the set temporary output power and an output limit of a battery, where the hysteresis width is set on the basis of, an input / output difference as a difference between the output limit and an input limit of the battery.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle, and more particularly, to a control device for a hybrid vehicle that is mounted on a hybrid vehicle together with an engine, first and second motors, a planetary gear, and a battery, and controls the engine and the first and second motors.

Background Art

[0002] Conventionally, as a control device for this type of hybrid vehicle, a device that is mounted on a hybrid vehicle together with an engine, first and second motors, a planetary gear, and a battery has been proposed (see, for example, Patent Document 1). The planetary gear has three rotating elements connected to the rotating shaft of the first motor, the output shaft of the engine, and the drive shaft connected to the drive wheels. The second motor has a rotating shaft connected to the drive shaft. The battery exchanges power with the first and second motors. In this device, when the power generated by the first and second motors at the time of starting is greater than the input limit of the battery, the first motor motors the engine to consume power with the first motor, and then starts and travels with the output of power from the engine with power generation by the first motor to the drive shaft. The engine and the first and second motors are controlled so as to start and travel. Since starting is performed while suppressing charging of the battery with power exceeding the input limit, starting performance can be ensured while protecting the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above hybrid vehicle control device, when the power output from the engine fluctuates, the torques of the first and second motors fluctuate. Since the second motor inputs and outputs power to the drive shaft, when the torque of the second motor fluctuates, vehicle vibration occurs. As a method for suppressing such vehicle vibration, the temporary output power of the first motor is set to be constant within the range of the hysteresis width centered on the target power based on the torque command of the first motor, and the second motor is driven within the range of the power limit value of the second motor based on the temporary output power and the output limit of the battery. However, when the hysteresis width is constant, depending on the value of the temporary output power, the power limit value of the second motor becomes small, and the second motor cannot output sufficient torque, and the desired torque cannot be output to the drive shaft. If the hysteresis width is reduced to output the desired torque to the drive shaft, the vibration of the vehicle becomes large.

[0005] The main object of the hybrid vehicle control device of the present invention is to suppress vehicle vibration while suppressing the inability to output a desired torque to the drive shaft.

Means for Solving the Problems

[0006] The hybrid vehicle control device of the present invention has adopted the following means in order to achieve the above main object.

[0007] The hybrid vehicle control device of the present invention is a hybrid vehicle control device mounted on a hybrid vehicle together with an engine, a first motor, a planetary gear having three rotating elements connected to the rotating shaft of the first motor, the output shaft of the engine, and a drive shaft connected to drive wheels, a second motor having a rotating shaft connected to the drive shaft, and a battery for exchanging power with the first and second motors, and controlling the engine and the first and second motors. When the vehicle speed is equal to or lower than a predetermined vehicle speed, the temporary output power of the first motor is set to be constant within a range of a hysteresis width centered on the target power to be output from the first motor, and the second motor is controlled to be driven within a range of the power limit value of the second motor based on the set temporary output power and the output limit of the battery. The hysteresis width is set based on the input / output difference that is the difference between the output limit and the input limit of the battery. This is the gist.

[0008] In the control device for a hybrid vehicle of the present invention, when the vehicle speed is equal to or lower than a predetermined vehicle speed, the temporary output power of the first motor is set to be constant within a range of a hysteresis width centered on the target power to be output from the first motor, and the second motor is controlled to be driven within a range of the power limit value of the second motor based on the set temporary output power and the output limit of the battery. Examples of the "predetermined vehicle speed" include a vehicle speed that is predetermined in advance as a threshold value for determining whether or not the vehicle is likely to stop. Then, the hysteresis width is set based on the input / output difference that is the difference between the output limit and the input limit of the battery. Thereby, even when the state of the battery deteriorates and the absolute value of either the output limit or the input limit of the battery becomes the value 0, while suppressing the hysteresis width from becoming the value 0, the temporary output power of the first motor can be made closer to the target power of the first motor. Since the hysteresis width can be suppressed from becoming the value 0, frequent changes in the temporary output power of the first motor can be suppressed compared to those in which the hysteresis width becomes the value 0. As a result, torque fluctuations of the second motor can be suppressed, and vibrations of the vehicle can be suppressed. Also, since the temporary output power of the first motor can be made closer to the target power of the first motor, it is possible to suppress the situation where the temporary output power becomes excessive with respect to the target power of the first motor, the power limit value of the second motor becomes too small, and the driving of the second motor is excessively restricted, and it is possible to suppress the situation where the desired torque cannot be output to the drive shaft. As a result, it is possible to suppress the vibrations of the vehicle while suppressing the situation where the desired torque cannot be output to the drive shaft.

[0009] In such a control device for a hybrid vehicle according to the present invention, the hysteresis width may be set such that it is smaller when the input-output difference is small than when it is large. By doing so, it is possible to further suppress the situation where the desired torque cannot be output to the drive shaft.

[0010] In this case, the hysteresis width may be set to the input-output difference, or may be set to a value obtained by multiplying the input-output difference by a predetermined coefficient that is a positive value. By doing so, the hysteresis width can be set more appropriately.

[0011] Also, in the control device for a hybrid vehicle according to the present invention, the hysteresis width may be set to the smaller value between the input-output difference and the maximum value of the input-output difference within which the vibration of the vehicle is allowed. By doing so, the vibration of the vehicle can be suppressed within the allowable range.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Next, a mode for carrying out the present invention will be described using examples.

EXAMPLE

[0014] FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50 as a power storage device, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0015] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil. The engine 22 is operationally controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24.

[0016] The engine ECU 24 is configured as a microprocessor centered around a CPU, and in addition to the CPU, it includes a ROM for storing processing programs, a RAM for temporarily storing data, input / output ports, and communication ports. Signals from various sensors necessary for controlling the operation of the engine 22 are input into the engine ECU 24 via the input ports. Examples of the signals input into the engine ECU 24 include the crank angle θcr from the crank position sensor 23 that detects the rotational position of the crankshaft 26, and the coolant temperature Tw from a water temperature sensor (not shown) that detects the temperature of the coolant of the engine 22. Also, the throttle opening TH from a throttle valve position sensor (not shown) that detects the position of the throttle valve, the intake air amount Qa from an air flow meter (not shown) attached to the intake pipe, and the intake air temperature Ta from a temperature sensor (not shown) attached to the intake pipe can be mentioned. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via the output ports. Examples of the signals output from the engine ECU 24 include drive control signals to the throttle motor that adjusts the position of the throttle valve, drive control signals to the fuel injection valves, and drive control signals to the ignition coil integrated with the igniter. The engine ECU 24 is connected to the HV ECU 70 via the communication port. The engine ECU 24 calculates the rotational speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor 23.

[0017] The planetary gear 30 is configured as a single-pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30. The drive shaft 36, which is connected to the drive wheels 39a and 39b via the differential gear 38, is connected to the ring gear of the planetary gear 30. The crankshaft 26 of the engine 22 is connected to the carrier of the planetary gear 30 via the damper 28.

[0018] The motor MG1 is configured as, for example, a synchronous generator motor. As described above, the rotor is connected to the sun gear of the planetary gear 30. The motor MG2 is configured as, for example, a synchronous generator motor, and the rotor is connected to the drive shaft 36. The inverters 41 and 42 are connected to the motors MG1 and MG2 and are also connected to the battery 50 via the power line 54. The motors MG1 and MG2 are rotationally driven by the motor electronic control unit (hereinafter referred to as "motor ECU") 40 by switching control of a plurality of switching elements (not shown) of the inverters 41 and 42.

[0019] Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU. In addition to the CPU, it includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors necessary for driving and controlling the motors MG1 and MG2 are input to the motor ECU 40 via the input port. For example, the rotational positions θm1 and θm2 from the rotational position detection sensors 43 and 44 that detect the rotational positions of the rotors of the motors MG1 and MG2, and the phase currents from the current sensors that detect the currents flowing in each phase of the motors MG1 and MG2. Switching control signals and the like to a plurality of switching elements (not shown) of the inverters 41 and 42 are output from the motor ECU 40 via the output port. The motor ECU 40 is connected to the HVECU 70 via the communication port. The motor ECU 40 calculates the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotational position detection sensors 43 and 44.

[0020] The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the inverters 41 and 42 via the power line 54. This battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0021] The battery ECU 52 is configured as a microprocessor centered around a CPU, although not shown in the figure. In addition to the CPU, it includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors necessary for managing the battery 50 are input to the battery ECU 52 via the input port. Examples of the signals input to the battery ECU 52 include the voltage Vb of the battery 50 from the voltage sensor 51a installed between the terminals of the battery 50, the current Ib of the battery 50 from the current sensor 51b attached to the output terminal of the battery 50, and the temperature Tb of the battery 50 from the temperature sensor 51c attached to the battery 50. The battery ECU 52 is connected to the HV ECU 70 via the communication port. The battery ECU 52 calculates the state of charge SOC based on the integrated value of the current Ib of the battery 50 from the current sensor 51b, or calculates the input / output limits Win, Wout based on the calculated state of charge SOC and the temperature Tb of the battery 50 from the temperature sensor 51c. The state of charge SOC is the ratio of the capacity of the power that can be discharged from the battery 50 to the total capacity of the battery 50. The input / output limits Win, Wout are the allowable charge / discharge power at which the battery 50 can be charged and discharged.

[0022] The battery ECU 52 sets the input and output limits Win and Wout of the battery 50 by the following method. Regarding the input limit Win, first, a basic value Winb (negative value) of the input limit Win is set based on the temperature Tb of the battery 50, a correction coefficient for input limit (positive value) is set based on the state of charge SOC of the battery 50, and the normal input limit Winn (negative value) is set by multiplying the set basic value Winb by the correction coefficient for input limit. Then, the larger value (the smaller value in terms of absolute value) between the set normal input limit Winn and the protection input limit Winp (negative value) which is the maximum power allowed to be input to the inverter 41 from the perspective of protecting the inverter 41 is set as the input limit Win. Regarding the output limit Wout, first, a basic value Woutb (positive value) of the output limit Wout is set based on the temperature Tb of the battery 50, a correction coefficient for output limit (positive value) is set based on the state of charge SOC of the battery 50, and the normal output limit Woutn (positive value) is set by multiplying the set basic value Woutb by the correction coefficient for output limit (positive value). Then, the smaller value between the set normal output limit Woutn and the protection output limit Woutp (positive value) which is the maximum power allowed to be output from the inverter 42 from the perspective of protecting the inverter 42 is set as the output limit Wout. An example of the relationship between the temperature Tb of the battery 50 and the basic values Winb and Woutb is shown in FIG. 2, and an example of the relationship between the state of charge SOC of the battery 50 and the input / output limit correction coefficient is shown in FIG. 3.

[0023] The HVECU 70 is configured as a microprocessor centered around a CPU (not shown). In addition to the CPU, it includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors are input into the HVECU 70 via the input port. Examples of signals input into the HVECU 70 include an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operating position of the shift lever 81. Also, an accelerator opening Acc from the accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83, a brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, and a vehicle speed V from the vehicle speed sensor 88 can be mentioned. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port.

[0024] The hybrid vehicle 20 of the embodiment configured in this way controls the engine 22 and the motors MG1 and MG2 so as to run in a hybrid driving mode (HV driving mode) accompanied by the operation of the engine 22 or an electric driving mode (EV driving mode) accompanied by the stop of the operation of the engine 22.

[0025] Next, the operation of the hybrid vehicle 20 of the embodiment configured in this way will be described. FIGS. 4 and 5 are flowcharts showing an example of a drive control routine executed by the HVECU 70 of the hybrid vehicle 20 of the embodiment. This routine is repeatedly executed at predetermined intervals (for example, every few msec).

[0026] When this routine is executed, the CPU of the HVECU 70 first performs a process of inputting data necessary for control, such as the accelerator opening Acc from the accelerator pedal 83, the vehicle speed V from the vehicle speed sensor 88, the engine speed Ne of the engine 22 from the engine ECU 24, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 from the motor ECU 40, and the input / output limits Win and Wout from the battery ECU 52 (step S100).

[0027] Subsequently, a required torque Tr* required for the drive shaft 36 is set based on the accelerator opening Acc and the vehicle speed V, and a required power Pe* that the engine 22 should output is set (step S110). In the embodiment, for the setting of the required torque Tr*, the relationship between the accelerator opening Acc, the vehicle speed V, and the required torque Tr* is obtained in advance and stored in the ROM as a required torque setting map. When the accelerator opening Acc and the vehicle speed V are given, the corresponding required torque Tr* is derived from the required torque setting map and set. An example of the required torque setting map is shown in FIG. 6. In the embodiment, for the setting of the required power Pe* of the engine 22, the required power Pd* required for running (required for the drive shaft 36) is calculated by multiplying the set required torque Tr* by the rotational speed Nd (rotational speed Nm2 of the motor MG2) of the drive shaft 36, and the required power Pe* required for the vehicle (required for the engine 22) is calculated by subtracting the charge / discharge required power Pb* (positive value when discharging from the battery 50) based on the state of charge SOC of the battery 50 from the required power Pd*.

[0028]

[0029] After setting the required torque Tr* and the required power Pe*, among the operating points (points determined from torque and rotational speed) of the engine 22 where the set required power Pe* can be output, the points at which the engine 22 can operate efficiently are set as the target torque Te* and the target rotational speed Ne* of the engine 22 (step S120).Then, using the torque command of the motor MG1 (previous Tm1*) set in the process of step S170 described later and the gear ratio ρ of the planetary gear 30 (number of teeth of the sun gear 31 / number of teeth of the ring gear 32) when the previous routine is executed, the output torque Teest as the torque estimated to be output from the engine 22 is calculated by the following equation (1) (step S130).

[0030] Teest = (1 + ρ) · previous Tm1* / ρ (1)

[0031] Next, using the target rotational speed Ne* of the engine 22, the rotational speed Nm2 of the motor MG2, and the gear ratio ρ of the planetary gear 30, the target rotational speed Nm1* of the motor MG1 is calculated by equation (2). Then, using the calculated target rotational speed Nm1* of the motor MG1, the rotational speed Nm1 of the motor MG1 input in step S100, the output torque Teest of the engine 22 set in step S130, and the gear ratio ρ of the planetary gear 30, the temporary torque Tm1tmp as the temporary value of the torque command Tm1* of the motor MG1 is calculated by equation (3) (step S140). Equation (3) is the relational expression in the feedback control for rotating the motor MG1 at the target rotational speed Nm1* (rotating the engine 22 at the target rotational speed Ne*). In equation (3), the first term on the right side is the feedforward term, and the second and third terms on the right side are the proportional term and integral term of the feedback, respectively. The first term on the right side can be easily derived using a nomograph. Also, "k1" in the second term on the right side is the gain of the proportional term, and "k2" in the third term on the right side is the gain of the integral term.

[0032] Nm1* = Ne* · (1 + ρ) / ρ - Nm2 · ρ (2) Tm1tmp = -ρ · Teest / (1 + ρ) + k1 · (Nm1* - Nm1) + k2 · ∫(Nm1* - Nm1)dt (3)

[0033] Subsequently, as shown in the following equation (4), the temporary torque Tm2tmp as the temporary value of the torque command Tm2* of the motor MG2 is calculated by adding the result of dividing the torque command Tm1* of the motor MG1 by the gear ratio ρ of the planetary gear 30 to the required torque Tr* (step S150).

[0034] Tm2tmp = Tr* + Tm1* / ρ (4)

[0035] Then, torque limits Tm1min and Tm1max as the upper and lower limits of the torque that may be output from motor MG1 and that satisfy both of the following expressions (5) and (6) are set (step S160). Here, expression (5) represents the relationship that the sum of the torques output to the ring gear shaft 32a from motor MG1 and motor MG2 is within the range from value 0 to the required torque Tr*, and expression (6) represents the relationship that the sum of the electric powers input and output by motor MG1 and motor MG2 is within the input / output limits Win and Wout of battery 50. FIG. 7 is an explanatory diagram showing an example of the torque limits Tm1min and Tm1max of motor MG1. The torque limits Tm1min and Tm1max can be obtained as the maximum and minimum values of the provisional torque Tm1tmp in the region indicated by the hatched lines in the figure. As can be seen from FIG. 7, when the required torque Tr* is a positive value, the drive point of motor MG1 that satisfies the relationship that the sum of the torques output to the drive shaft 36 from motor MG1 and motor MG2 is the required torque Tr* and the relationship that the sum of the electric powers input and output by motor MG1 and motor MG2 is the input limit Win of battery 50 is set as the torque limit Tm1min. That is, the torque limit Tm1min is calculated by expression (7) obtained from expressions (5) and (6). Further, the drive point of motor MG1 that satisfies the relationship that the sum of the torques output to the drive shaft 36 from motor MG1 and motor MG2 is value 0 and the relationship that the sum of the electric powers input and output by motor MG1 and motor MG2 is the output limit Wout of battery 50 is set as the torque limit Tm1max. That is, the torque limit Tm1max is calculated by expression (8) obtained from expressions (5) and (6).

[0036] 0 ≦ -Tm1tmp / ρ + Tm2tmp ≦ Tr* (5) Win ≦ Tm1tmp·Nm1 + Tm2tmp·Nm2 ≦ Wout (6) Tm1min = (Win - Tr*·Nm2) / (Nm1 + Nm2 / ρ) (7) Tm1max = Wout / Nm1r + Nm2 / ρ (8)

[0037] When the torque limits Tm1min and Tm1max are set in this way, as shown in the following formula (9), the larger value between the smaller value of the temporary torque Tm1tmp of the motor MG1 and the torque limit Tm1max, and the torque limit Tm1min is set as the torque command Tm1* of the motor MG1 (the temporary torque Tm1tmp of the motor MG1 is limited by the torque limits Tm1min and Tm1max to set the torque command Tm1* of the motor MG1) (step S170).

[0038] Tm1* = max(min(Tm1tmp, Tm1max), Tm1min) (9)

[0039] Subsequently, the target power Pm1 to be output from the motor MG1 is calculated from the product of the calculated torque command Tm1* of the motor MG1 and the rotational speed Nm1 of the motor MG1 input in step S100 (step S180).

[0040] Subsequently, it is determined whether or not the vehicle speed V input in step S100 is less than or equal to a predetermined vehicle speed Vref (step S190). The predetermined vehicle speed Vref is a vehicle speed predetermined in advance as a threshold for determining whether or not the vehicle is likely to stop.

[0041] When the vehicle speed V exceeds the predetermined vehicle speed Vref in step S190, it is determined that the vehicle is not likely to stop, and the output of the motor MG1 is reduced from the output limit Wout and the input limit Win of the battery 50, and the hysteresis width His used for setting the output of the motor MG1 when setting the output limit of the motor MG2 (hereinafter, this is referred to as the temporary power (temporary output power) Pm1his of the motor MG1) is set to a predetermined width ΔWmax (step S200). The predetermined width ΔWmax is a value determined in advance by experiments or analysis as a constant value considering suppressing frequent changes in the output allowable range P2 of the motor MG2 described later.

[0042] When the hysteresis width His is set, the provisional power Pm1his of the motor MG1 is calculated using the following equation (10) based on the set hysteresis width His (step S220). In equation (10), "previous Pm1his" is the provisional power of the motor MG1 calculated in step S230 of the previous routine of this routine.

[0043] Pm1his = min(max(previous Pm1his, Pm1 - His), Pm1 + His) (10)

[0044] Fig. 8 shows how the provisional power Pm1his of the motor MG1 is set. In the figure, the solid line indicates the target power Pm1 of the motor MG1, and the dashed line indicates the provisional power Pm1his of the motor MG1. As shown in Fig. 8 and equation (10), when the previous provisional power (previous Pm1his) of the motor MG1 is within the hysteresis width His centered on the target power Pm1 of the motor MG1, the previous provisional power is set as the provisional power Pm1his of the motor MG1. When the previous provisional power is not within the range of the hysteresis width His, it is changed to be within that range, and the provisional power Pm1his of the motor MG1 is set. Since the provisional power Pm1his of the motor MG1 is directly reflected in the setting of the output allowable range P2 of the motor MG2, which is the output limit of the motor MG2, by adjusting the provisional power Pm1his of the motor MG1 to be as constant as possible within the range of the hysteresis width His centered on the target power Pm1, it is possible to prevent the output allowable range P2 of the motor MG2 from being frequently changed.

[0045] After setting the provisional power Pm1his of the motor MG1 in this way, the output lower limit value and the output upper limit value of the motor MG2 are calculated by subtracting the set provisional power Pm1his from the output limit Wout and the input limit Win of the battery 50 input in step S100, respectively, to set the output allowable range P2 (step S230). At the same time, the output lower limit value and the output lower limit value of the motor MG2 in the output allowable range P2 are divided by the rotational speed Nm2 of the motor MG2 to calculate the torque limits Tm2min and Tm2max of the motor MG2 (step S240).

[0046] Then, the smaller value among the larger value of the temporary torque Tm2tmp set in step S150 and the torque limit Tm2min, and the torque limit Tm2max is set as the torque command Tm2* (the value obtained by limiting the temporary torque Tm2tmp by the torque limits Tm2min and Tm2max is set as the torque command Tm2*) (step S250). Then, the target torque Te* of the engine 22 is transmitted to the engine ECU 24, and the torque commands Tm1*, Tm2* of the motors MG1, MG2 are transmitted to the motor ECU 40 (step S260), and this routine is terminated. The engine ECU 24 that has received the target torque Te* performs controls such as ignition control and fuel injection control so that a torque corresponding to the target torque Te* is output from the engine 22. The motor ECU 40 that has received the torque commands Tm1*, Tm2* performs switching control of the switching elements of the inverters 41, 42 so that a torque corresponding to the torque command Tm1* is output from the motor MG1 and a torque corresponding to the torque command Tm2* is output from the motor MG2. In this way, when the vehicle speed V exceeds the predetermined vehicle speed Vref, by setting the hysteresis width His to the predetermined width ΔWmax, frequent changes in the output allowable range P2 of the motor MG2 are suppressed, frequent changes in the temporary power Pm1his of the motor MG1 are suppressed, and frequent changes in the torque limits Tm2min and Tm2max are suppressed. As a result, frequent changes in the torque command Tm2* are suppressed, and vibrations of the vehicle due to fluctuations in the torque output from the motor MG2 can be suppressed.

[0047] When the vehicle speed V is less than or equal to the predetermined vehicle speed Vref in step S190, it is determined that the vehicle is likely to stop. Then, the input-output difference |Wout - Win|, which is the absolute value of the value obtained by subtracting the input limit Win from the output limit Wout, is set as the hysteresis width His (step S210). Using the set hysteresis width His, the provisional power Pm1his of the motor MG1 is set (step S220). Using the provisionally set power Pm1his, the output allowable range P2 of the motor MG2 is calculated (step 230). Torque limits Tm2min and Tm2max are set so that the power output from the motor MG2 is within the output allowable range P2 (step S240). The provisional torque Tm2tmp is set as the torque command Tm2* with the torque limited by the torque limits Tm2min and Tm2max (step S250). The target torque Te*, torque commands Tm1* and Tm2* are transmitted to each ECU (step S260), and this routine ends.

[0048] Since the input / output difference |Wout - Win| is set to the hysteresis width His in step S210, the hysteresis width His is set to be narrower as the output limit Wout is smaller and as the input limit Win is larger (as the absolute value of the input limit Win is smaller), within a range not falling below the value 0. The narrower the hysteresis width His is set, the closer the temporary power Pm1his of the motor MG1 is set to the target power Pm1 of the motor MG1. Therefore, when the state of the battery 50 deteriorates and the output limit Wout and the input limit Win of the battery 50 become smaller, the temporary power Pm1his is set to a value close to the target power Pm1 of the motor MG1. Thus, it is suppressed that the temporary power Pm1his becomes excessive with respect to the target power Pm1 of the motor MG1 and the upper limit value of the output allowable range P2 of the motor MG2 (=Wout - Pm1his) becomes too small, resulting in a decrease in the torque limit Tm2max and an excessive decrease in the torque command Tm2*. Thereby, it can be suppressed that the motor MG2 cannot output a desired torque and that the desired torque (required torque Tr*) cannot be output to the drive shaft 36. Therefore, it can be suppressed that the torque that can be output from the motor MG2 becomes small and the vehicle cannot start after stopping. Also, since the hysteresis width His is set to the input / output difference |Wout - Win|, when the output limit Wout is 0 and the input limit Win is not 0, the hysteresis width His can be set wider than 0. The wider the hysteresis width His is set, the more frequent changes in the temporary power Pm1his of the motor MG1 are suppressed, and the more frequent changes in the torque command Tm2* of the motor MG2 are suppressed. Thereby, torque fluctuations output from the motor MG2 can be suppressed, and vibrations of the vehicle can be suppressed. Therefore, it is possible to suppress the vehicle from vibrating while suppressing the inability to output a desired torque to the drive shaft 36.

[0049] According to the hybrid vehicle 20 of the embodiment described above, when the vehicle speed V is less than or equal to the predetermined vehicle speed Vref, the temporary power Pm1his (temporary output power) of the first motor is set to be constant within the range of the hysteresis width His centered on the target power Pm1 of the motor MG1, and the motor MG2 is controlled to drive within the allowable output range P2 of the motor MG2 (within the range of the power limit value of the motor MG2) based on the set temporary power Pm1his and the input limit Win and output limit Wout of the battery. By setting the hysteresis width His to the input-output difference |Wout - Win|, which is the difference between the output limit Wout and the input limit Win of the battery 50, it is possible to suppress vehicle vibration and prevent the drive shaft 36 from being unable to output the desired torque.

[0050] In the hybrid vehicle 20 of the embodiment, the hysteresis width His is set to the input-output difference |Wout - Win|. However, since the hysteresis width His may be set to be smaller when the input-output difference |Wout - Win| is small than when it is large, the hysteresis width His may be set to a value obtained by multiplying the input-output difference |Wout - Win| by a predetermined coefficient with a positive value. Also, the hysteresis width His may be set based on the input-output difference |Wout - Win|. For example, it may be set to the smaller value between the input-output difference |Wout - Win| and the maximum value of the input-output difference |Wout - Win| that allows vehicle vibration. By doing so, it is possible to prevent the vehicle vibration from becoming excessive.

[0051] In the hybrid vehicle 20 of the embodiment, the input and output limits Win and Wout of the battery 50 are set by the battery ECU 52. However, the input and output limits Win and Wout may be set by other electronic control units such as the motor ECU 40 or the HV ECU 70, or may be set by a plurality of electronic control units (for example, the motor ECU 40 and the HV ECU 70, etc.).

[0052] In the hybrid vehicle 20 of the embodiment, the battery 50 is used as the power storage device, but a capacitor may also be used.

[0053] In the hybrid vehicle 20 of the embodiment, the engine ECU 24, the motor ECU 40, the battery ECU 52, and the HV ECU 70 are provided, but at least a part of these may be configured as a single electronic control unit.

[0054] In the hybrid vehicle 20 of the embodiment, the power of the motor MG2 is output to the drive shaft 36, but the power of the motor MG2 may be connected to an axle different from the axle to which the drive shaft 36 is connected (the axle to which the drive wheels 39a and 39b are connected).

[0055] The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor ECU 40, the battery ECU 52, and the HV ECU 70 correspond to the "control device for a hybrid vehicle".

[0056] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems is an example for specifically explaining the form for implementing the invention described in the column of means for solving the problems in the embodiment, and thus does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the column of means for solving the problems.

[0057] As described above, the embodiments have been used to explain the forms for implementing the present invention. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Industrial Applicability

[0058] The present invention can be used in the manufacturing industry of control devices for hybrid vehicles and the like.

Explanation of Reference Numerals

[0059] 20 Hybrid vehicle, 22 Engine, 23 Crank position sensor, 24 Engine electronic control unit (Engine ECU), 26 Crankshaft, 28 Damper, 30 Planetary gear, 36 Drive shaft, 38 Differential gear, 39a, 39b Drive wheels, 40 Motor electronic control unit (Motor ECU), 41, 42 Inverter, 43, 44 Rotation position detection sensor, 50 Battery, 51a Voltage sensor, 51b Current sensor, 51c Temperature sensor, 52 Battery electronic control unit (Battery ECU), 54 Power line, 70 Hybrid electronic control unit (HVECU), 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 88 Vehicle speed sensor, MG1, MG2 Motors.

Claims

Claim 1 An engine, a first motor, a planetary gear having three rotating elements connected to the rotating shaft of the first motor, the output shaft of the engine, and a drive shaft connected to drive wheels, a second motor having a rotating shaft connected to the drive shaft, a battery for exchanging power with the first and second motors, and a control device for a hybrid vehicle mounted on the hybrid vehicle and controlling the engine and the first and second motors, when the vehicle speed is equal to or lower than a predetermined vehicle speed, setting a temporary output power of the first motor so as to be constant within a range of a hysteresis width centered on a target power to be output from the first motor, and controlling the second motor so that the second motor is driven within a range of a power limit value of the second motor based on the set temporary output power and an output limit of the battery, setting the hysteresis width to a smaller value of an input / output difference as a difference between the output limit and the input limit of the battery and a maximum value of the input / output difference allowable for vehicle vibration A control device for a hybrid vehicle.

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