Control devices for electric vehicles

Abstract

A control device for an electric vehicle is provided that can simultaneously suppress the deterioration of fuel economy and improve acceleration performance. The control device (20) for the electric vehicle 1 is a control device (20) for an electric vehicle (1) having: an internal combustion engine (2), a generator (4), a front electric motor (6), a rear electric motor (8), and a drive battery (10). The generator (4) is driven by the internal combustion engine (2). Each electric motor drives the drive shaft of the electric vehicle (1). The drive battery (10) supplies power to each electric motor. The control device (20) for the electric vehicle (1) includes: a driving mode control unit (30), a battery output deficiency judgment unit (32), and a power generation control unit (34). The power generation control unit (34) controls the internal combustion engine (2) and the generator (4) based on a first power control. The power generation control unit (34) includes a first control mode and a second control mode. The first control mode controls the internal combustion engine (2) to change the speed of the internal combustion engine (2). The second control mode controls the generator (4) to change the speed of the internal combustion engine (2). When the driving mode control unit (30) switches to series mode and the battery output deficiency judgment unit (32) determines that there is a second power deficiency, the power generation control unit (34) switches from the second control mode to the first control mode.

Description

Technical Field

[0001] This invention relates to a control device for an electric vehicle equipped with a generator driven by an internal combustion engine. Background Technology

[0002] Conventional control devices for series hybrid electric vehicles (e.g., see Patent Document 1) are known, which generate electricity using a generator driven by an internal combustion engine, supply the generated electricity to an electric motor, and the electric motor drives a drive shaft. In the control device of Patent Document 1, when the generator speed increases due to an increase in the demand for power generation, the required torque for the internal combustion engine is added to the required torque, along with an inertial torque necessary to increase the generator speed. Thus, in the control device of Patent Document 1, the generator speed increases rapidly by adding the required torque to the internal combustion engine to the inertial torque. As a result, the acceleration performance of the electric vehicle is improved.

[0003] Furthermore, control devices for electric vehicles with parallel, series, and EV modes are known in the past (see, for example, Patent Document 2). In the electric vehicle control device of Patent Document 2, in series mode, when the target speed of the generator increases, the required torque demanded by the internal combustion engine is added to the inertial torque. Thus, in the electric vehicle control device of Patent Document 2, by adding the required torque demanded by the internal combustion engine to the inertial torque, the power generation can be stabilized. As a result, the acceleration performance of the electric vehicle is improved.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-20972

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-124318

[0008] The technical problem that the invention aims to solve

[0009] However, in the control devices of the electric vehicles in Patent Documents 1 and 2, the required torque for the internal combustion engine is added to the inertial torque used to increase the generator speed. Therefore, the internal combustion engine needs to output a torque corresponding to the amount of inertial torque. Consequently, the fuel injection quantity of the internal combustion engine increases, and fuel economy deteriorates. Summary of the Invention

[0010] The objective of this invention is to provide a control device for an electric vehicle that can simultaneously suppress the deterioration of fuel economy and improve acceleration performance.

[0011] Technical means for solving technical problems

[0012] The electric vehicle control device of the present invention comprises an internal combustion engine, a generator, an electric motor, and a drive battery mounted on the electric vehicle. The generator is driven by the internal combustion engine. The electric motor drives the drive shaft of the electric vehicle. The drive battery supplies power to the electric motor. The electric vehicle control device includes a driving mode control unit, a battery output insufficiency determination unit, and a power generation control unit. The driving mode control unit switches to a series mode, which drives the electric vehicle using a first power source and a second power source. The first power source is supplied from the generator to the electric motor, and the second power source is supplied from the drive battery to the electric motor. The battery output insufficiency determination unit determines whether the second power source is insufficient. The power generation control unit controls the internal combustion engine and the generator based on the first power source. The power generation control unit includes a first control mode and a second control mode. The first control mode controls the internal combustion engine to change its rotational speed. The second control mode controls the generator to change its rotational speed. When the driving mode control unit switches to the series mode and the battery output insufficiency determination unit determines that the second power source is insufficient, the power generation control unit switches from the second control mode back to the first control mode. Alternatively, the power generation control unit calculates the target speed based on the first power supply and sets a lower limit for the target speed, which serves as the target speed for the internal combustion engine. Alternatively, if the driving mode control unit switches to series mode and the battery output insufficiency judgment unit determines that the second power supply is insufficient, the power generation control unit performs corrective control to raise the lower limit.

[0013] According to the control device of this electric vehicle, when the second power supplied from the drive battery to the electric motor is insufficient, the generator control unit rapidly changes the speed of the internal combustion engine through a first control mode. This causes the first power supplied from the generator to the electric motor to change rapidly. Therefore, even when the second power is insufficient during series mode operation, the electric motor can quickly receive the first power supply. As a result, the acceleration performance of the electric vehicle is improved. On the other hand, when the second power is not insufficient, the generator control unit controls the generator through a second control mode, thereby changing the speed of the internal combustion engine. When the generator is controlled, the first power may decrease. However, since the internal combustion engine does not need to increase its speed itself, fuel economy improves. In other words, according to the control device of this electric vehicle, it is possible to simultaneously suppress the deterioration of the electric vehicle's fuel economy and improve its acceleration performance.

[0014] Furthermore, according to this structure, the power generation control unit can increase the engine speed from a high state. This allows the internal combustion engine to reach a higher speed more easily and quickly. Consequently, the generator can supply the first power to the electric motor earlier. As a result, even when the second power supply decreases, the acceleration performance of the electric vehicle can be improved.

[0015] Alternatively, the higher the speed of the electric vehicle, the larger the lower limit value will be adjusted by the power generation control unit.

[0016] According to this structure, the higher the speed of an electric vehicle, the easier it is for the internal combustion engine to reach a higher RPM sooner. On the other hand, at lower speeds, the internal combustion engine RPM decreases, thus reducing the noise and vibration caused by the engine's rotation.

[0017] The power generation control unit may also calculate the target speed based on the first power supply, which is the target speed of the internal combustion engine. Alternatively, if the target speed increases, the power generation control unit may calculate the rate of increase of the target speed and set a first limit value for the rate of increase. Alternatively, if the driving mode control unit switches to series mode and the battery output insufficiency judgment unit determines that there is a second power shortage, the power generation control unit may perform correction control to adjust the rate of increase to a second limit value greater than the first limit value.

[0018] Alternatively, the second limit value can be a value that decreases as the target rotational speed increases.

[0019] According to this structure, the generator control unit can rapidly increase the speed of the internal combustion engine. As a result, the internal combustion engine can easily reach higher speeds more quickly. Consequently, the generator can supply the first power to the electric motor more rapidly. Consequently, even when the second power source is insufficient, the acceleration performance of the electric vehicle can be improved.

[0020] The battery output deficiency determination unit may also include a battery temperature acquisition unit that acquires the temperature of the drive battery. Alternatively, if the temperature acquired by the battery temperature acquisition unit is below a first predetermined temperature or above a second predetermined temperature, the battery output deficiency determination unit determines that there is a second power deficiency.

[0021] The output of the drive battery may be limited at high temperatures. Furthermore, the output of the drive battery may decrease at low temperatures. According to this structure, the motor can quickly receive a first power supply under any condition.

[0022] Alternatively, the second limit value may be as follows: compared to the case where the temperature of the drive battery obtained by the battery output deficiency determination unit is below the first predetermined temperature, the second limit value is smaller when the temperature of the drive battery obtained by the battery output deficiency determination unit is above the second predetermined temperature.

[0023] According to the results, when the temperature of the drive battery is above the second predetermined temperature, the second limit value is suppressed to a lower level. Therefore, when the drive battery is at a high temperature, the engine speed increases slowly compared to when the drive battery is at a low temperature. As a result, noise and vibration caused by engine rotation can be reduced. On the other hand, when the temperature of the drive battery is below the first predetermined temperature, the engine speed increases rapidly compared to when the drive battery is at a high temperature.

[0024] The generator control unit can also calculate the rotational torque that increases the speed of the internal combustion engine. The generator control unit can also acquire the actual speed of the internal combustion engine. Alternatively, in the first control mode, the generator control unit can suppress the rotational torque based on the actual speed.

[0025] Alternatively, when the actual rotational speed is greater than the target rotational speed, the power generation control unit suppresses the rotational torque increase.

[0026] Alternatively, the power generation control unit can suppress the increasing rotational torque as the actual rotational speed increases.

[0027] This structure can suppress excessive rotational increase when the internal combustion engine speed increases.

[0028] Alternatively, the control device of the electric vehicle may also include a throttle opening determination unit, which determines the throttle opening. Alternatively, when the throttle is cut off, the power generation control unit switches from a first control mode to a second control mode.

[0029] According to this structure, when the accelerator is not depressed, the engine speed changes through the second control mode. As a result, fuel economy is improved.

[0030] Alternatively, when the electric vehicle's speed is above the first specified speed, the battery output insufficiency judgment unit judges it as a second power insufficiency.

[0031] This structure improves the acceleration performance of electric vehicles at high speeds.

[0032] Alternatively, the first specified temperature can be calculated based on either or both of the degradation of the driving battery and the charging rate of the driving battery.

[0033] According to this structure, the insufficiency of the second power can be quickly determined using a first specified temperature based on either or both of the degradation of the driving battery and the charging rate.

[0034] The power generation control unit can also calculate the target power generation based on the first power output, which is the target power generation for the generator. The power generation control unit can also obtain the actual power generation from the generator. Alternatively, if the actual power generation is less than the target power generation, the power generation control unit can switch from the second control mode to the first control mode.

[0035] According to this structure, when the actual power generation is less than the target power generation, the power generation control unit rapidly increases the speed of the internal combustion engine through a first control mode. This causes a rapid increase in the first power supplied from the generator to the electric motor. Therefore, even when the second power is insufficient, the acceleration performance of the electric vehicle can be improved.

[0036] Alternatively, the power generation control unit calculates the target speed based on the first power and sets a lower limit for the target speed, which is the target speed of the internal combustion engine. When the driving mode control unit switches to series mode and the battery output insufficiency judgment unit determines that the second power is insufficient, the power generation control unit limits the upper limit to below the specified speed.

[0037] According to this structure, it is possible to suppress the deterioration of fuel economy and improve acceleration performance of electric vehicles, and to suppress the deterioration of vibration / noise that accompanies the increase in internal combustion engine speed.

[0038] The specified speed can also be the point at which the output characteristics of an internal combustion engine change.

[0039] According to this structure, for example, the power generation control unit can increase the speed of the internal combustion engine until the output speed increases at a substantially constant slope relative to the speed of the internal combustion engine. Thus, the power generation control unit can efficiently utilize the output of the internal combustion engine to generate electricity for the generator.

[0040] Alternatively, if the speed of the electric vehicle is less than the second specified speed, the power generation control unit may limit the upper limit to below the specified speed.

[0041] According to this structure, the vibration / noise can be made to a degree corresponding to a second specified speed.

[0042] Alternatively, when the speed of the electric vehicle is above the second specified speed, the power generation control unit increases the upper limit value as the speed increases.

[0043] This structure can suppress the feeling of idling and increase the speed of the internal combustion engine.

[0044] The effects of the invention

[0045] According to the present invention, a control device for an electric vehicle can be provided that can simultaneously suppress the deterioration of the fuel economy of the electric vehicle and improve its acceleration performance. Attached Figure Description

[0046] Figure 1 This is a system diagram of an electric vehicle according to an embodiment of the present invention.

[0047] Figure 2 This is a block diagram illustrating the structure of a control device for an electric vehicle according to an embodiment of the present invention.

[0048] Figure 3 This is a diagram illustrating an example of a three-dimensional mapping of an embodiment of the present invention.

[0049] Figure 4 This is a graph showing the change of the target engine speed Ert relative to the throttle opening in an embodiment of the present invention.

[0050] Figure 5 This is a graph illustrating an example of the relationship between the increase rate limit value dErtLim and the target engine speed Ert in an embodiment of the present invention.

[0051] Figure 6 This is a graph illustrating an example of the relationship between the rotational lifting torque UTq and the engine speed deviation in an embodiment of the present invention.

[0052] Figure 7 This is a graph illustrating an example of the relationship between the rotational lifting torque UTq and the actual engine speed Erq in an embodiment of the present invention.

[0053] Figure 8 This is a flowchart illustrating the control sequence of the control device in an embodiment of the present invention.

[0054] Figure 9 This is a timing diagram showing the change of the target engine speed Ert when the upper limit of the target engine speed Ert is changed according to an embodiment of the present invention.

[0055] Figure 10 This is a graph illustrating an example of the output characteristics of an internal combustion engine according to an embodiment of the present invention. Detailed Implementation

[0056] <First Implementation>

[0057] Hereinafter, the control device 20 of the electric vehicle 1 according to the first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1As shown, the electric vehicle 1 of this embodiment is a four-wheel drive hybrid electric vehicle. The electric vehicle 1 includes: an internal combustion engine (ENG) 2, a generator (GEN) 4, a front electric motor (FrM) 6, a rear electric motor (RM) 8, a drive battery (BT) 10, a control unit (HVECU) 20, and an accelerator pedal 21. In the electric vehicle 1 of this embodiment, the front electric motor 6 drives the front wheel drive axle 12a of the front wheels 12 via a transmission drive axle 16. The rear electric motor 8 drives the rear wheel drive axle 14a of the rear wheels 14 via a reducer 8c. The front electric motor 6 is connected to the drive battery 10 via a front inverter 18, and is supplied with power (secondary power) from the drive battery 10. The front inverter 18 includes: a front electric motor control unit (FrMCU) 6a and a generator control unit (GCU) 4a that controls the generator 4. The front electric motor control unit 6a receives signals from the control unit 20 and controls the regeneration and power operation of the front electric motor 6 to achieve the desired operating state of the front electric motor 6. Similarly, the rear motor 8 is connected to the drive battery 10 via the rear inverter 8b, and is supplied with power (secondary power) from the drive battery 10. The rear inverter 8b has a rear motor control unit (RMCU) 8a. The rear motor control unit 8a receives signals from the control unit 20 and controls the regeneration and power operation of the rear motor 8 to make the rear motor 8 operate in the desired state.

[0058] The internal combustion engine 2 drives the generator 4 via the transmission drive axle 16. The internal combustion engine 2 is driven by the combustion of fuel supplied from the fuel tank 22. Various devices and sensors of the internal combustion engine 2 are electrically connected to the engine control unit (ENG-ECU) 2a. The ENG-ECU 2a receives signals from the control unit 20 and controls the internal combustion engine 2 to achieve the desired operating state. The transmission drive axle 16 amplifies the rotational speed of the internal combustion engine 2 and transmits it to the generator 4. In addition, the transmission drive axle 16 in this embodiment has a clutch 16a, which transmits or disconnects power between the internal combustion engine 2 and the front electric motor 6, and between the internal combustion engine 2 and the front wheel drive axle 12a. The internal combustion engine 2 is connected to the front wheel drive axle 12a via the clutch 16a of the transmission drive axle 16, thereby driving the front wheel drive axle 12a.

[0059] The generator 4 generates electricity by being driven by the internal combustion engine 2. The electricity generated by the generator 4 (first electricity) can charge the drive battery 10 and can be supplied to the front motor 6 and the rear motor 8 (hereinafter referred to as each motor) via the front inverter 18 and the rear inverter 8b. In this embodiment, the generator 4 is an electric generator that can drive the internal combustion engine 2 to rotate in addition to generating electricity. When driven by the internal combustion engine 2, the generator 4 generates electricity by applying a load to the generator 4. On the other hand, the generator 4 drives the internal combustion engine 2 to start by performing power operation by being supplied with electricity from the drive battery 10. The generator 4 is controlled by a generator control device 4a provided in the front inverter 18. The generator control device 4a is electrically connected to the control device 20, receives signals from the control device 20, and controls the power generation and power operation to make the generator 4 operate in the desired state.

[0060] The drive battery 10 is composed of a secondary battery such as a lithium-ion battery and has a battery module (not shown) that integrates multiple battery elements. The drive battery 10 functions as a power source for each electric motor. Furthermore, the drive battery 10 has a battery monitoring unit (BMU) 10a, which calculates the state of charge (SOC) of the battery module, detects the state of health (SOH) of the battery module, and monitors the voltage Bv and temperature Btmp of the battery module. The battery monitoring unit 10a acquires the battery temperature Btmp of the drive battery 10 and sends it to the control device 20.

[0061] The control unit 20 is actually composed of a microcomputer including a computing device, memory, input / output buffer, etc. The control unit 20 controls the various devices based on signals from various sensors and devices, as well as the mapping and programs stored in the memory, so as to make the electric vehicle 1 operate in the desired state.

[0062] In this embodiment, the various control devices, including the engine control unit 2a, generator control unit 4a, front motor control unit 6a, rear motor control unit 8a, and battery monitoring unit 10a, are separately installed from the control unit 20. Each control device is electrically connected to the control unit 20. However, the various control devices can also be integrated with the control unit 20. Like the control unit 20, each control device is composed of a microcomputer including a computing device, memory, input / output buffer, etc.

[0063] like Figure 2As shown, the control device 20 includes a driving mode control unit 30, a battery output deficiency judgment unit 32, a power generation control unit 34, and a throttle opening judgment unit 36. The driving mode control unit 30, the battery output deficiency judgment unit 32, the power generation control unit 34, and the throttle opening judgment unit 36 ​​are functional structures implemented by software stored in the control device 20. However, various controls are not limited to software-based processing; they can also be processed using dedicated hardware (electronic circuitry). Furthermore, the control device 20 acquires the rotational speeds of the front wheel 12 and the rear wheel 14 using wheel speed sensors (not shown), and calculates the speed V of the electric vehicle 1 based on the rotational speeds of the wheel speed sensors using a speed calculation unit 38.

[0064] The accelerator pedal 21 is a pedal used by the driver of the electric vehicle 1 to control the acceleration and deceleration of the electric vehicle 1. An accelerator position sensor 21a is provided on the accelerator pedal 21 to detect the depressed position. The accelerator position sensor 21a is electrically connected to the control device 20 and sends the accelerator depressed position (accelerator opening) to the control device 20. The accelerator opening determination unit 36 ​​includes a driver-required torque calculation unit 36a. The driver-required torque calculation unit 36a calculates the driver-required torque DTq of the electric vehicle 1 based on the accelerator opening Th obtained from the accelerator position sensor 21a.

[0065] The driving mode control unit 30 controls the clutch 16a based on information such as speed V, SOC, and throttle opening Th, thereby switching between parallel mode, series mode, and EV mode to any driving mode. In parallel mode, the driving mode control unit 30 engages the clutch 16a, and drives the front wheel drive shaft 12a via both the internal combustion engine 2 and the front electric motor 6. At this time, either or both of the power from the drive battery 10 (second power) and the power generated by the generator 4 (first power) are supplied to the front electric motor 6. Similarly, the rear electric motor 8 is also supplied with either or both of the power from the drive battery 10 (second power) and the power generated by the generator 4 (first power), driving the rear wheel drive shaft 14a. In EV mode, the driving mode control unit 30 disengages the clutch 16a and supplies the drive battery 10 power (second power) to each electric motor, thereby driving the front wheel drive shaft 12a and the rear wheel drive shaft 14a (hereinafter referred to as each drive shaft).

[0066] In series mode, the driving mode control unit 30 releases the clutch 16a, allowing the internal combustion engine 2 to drive the generator 4 and supply the first power generated by the generator 4 to each electric motor. Furthermore, if the driving force of each electric motor driving its drive shaft using the first power is insufficient, the driving mode control unit 30 also supplies a second power from the drive battery 10 to each electric motor. That is, in series mode, the driving mode control unit 30 uses both the first and second power to propel the electric vehicle 1. Thus, by combining the first power supplied from the generator 4 to each electric motor with the second power supplied from the drive battery 10 in series mode, the driving mode control unit 30 can effectively operate the internal combustion engine 2, reducing fuel consumption when the internal combustion engine 2 powers the generator 4, thereby improving the acceleration performance of the electric vehicle 1.

[0067] The driving mode control unit 30 includes: a drive shaft torque calculation unit 30a, a front-rear torque distribution calculation unit 30b, a front motor / engine torque distribution calculation unit 30c, a power conversion calculation unit 30d, and a drive shaft torque limit value calculation unit 30e. The drive shaft torque calculation unit 30a acquires the driver-required torque DTq and the upper limit drive shaft torque TqLim. Based on the driver-required torque DTq and the upper limit drive shaft torque TqLim, the drive shaft torque calculation unit 30a calculates the target drive shaft torque FRTq that each drive shaft needs to produce.

[0068] The upper limit drive shaft torque TqLim can be calculated by subtracting the power consumed by auxiliary equipment such as electronic devices mounted on the electric vehicle 1 and the losses in each motor from the power generation GWi based on the upper limit power W2 of the battery and the capacity of the generator 4 (described later), and then dividing the obtained value by the speed V and multiplying by the unit conversion factor. The upper limit drive shaft torque TqLim can be calculated in the drive shaft torque limit value calculation unit 30e. However, the target drive shaft torque FRTq is not limited to these calculation methods; for example, a mapping diagram can also be used. After performing these calculations, the drive shaft torque calculation unit 30a sends the target drive shaft torque FRTq to the power conversion calculation unit 30d. The power conversion calculation unit 30d converts the target drive shaft torque FRTq into a target power generation W1 and sends it to the power generation control unit 34.

[0069] The front and rear axle distribution calculation unit 30b acquires road conditions, etc., and calculates the target front axle torque FTq to be distributed to the front axle 12a and the target rear axle torque RTq to be distributed to the rear axle 14a based on the road conditions, etc., and sends them to the front motor control device 6a and the rear motor control device 8a. The front motor engine torque distribution calculation unit 30c calculates the parallel engine torque PETq required by the internal combustion engine 2 in parallel mode.

[0070] The battery output insufficiency determination unit 32 determines whether the second power supplied from the drive battery 10 to each motor is insufficient. The battery output insufficiency determination unit 32 includes a battery output calculation unit 32a. The battery output calculation unit 32a obtains the SOC, SOH, battery temperature Btmp, and voltage Bv of the drive battery 10 from the battery monitoring unit 10a, and calculates the upper limit power W2, which is the upper limit value of the second power that the drive battery 10 can supply to each motor. If the upper limit power W2 of the drive battery 10 is lower than the upper limit power W2 in the normal state, the battery output insufficiency determination unit 32 determines that the second power is insufficient.

[0071] In this embodiment, the battery output deficiency determination unit 32 includes a battery temperature acquisition unit 32b. The battery temperature acquisition unit 32b acquires the battery temperature Btmp from the battery monitoring unit 10a. If the battery temperature Btmp is below a first predetermined temperature T1, the battery output deficiency determination unit 32 determines that there is a second power deficiency. The first predetermined temperature T1 is a temperature preset on a mapping diagram based on SOC and SOH. More specifically, as... Figure 3 As shown in one example of the three-dimensional mapping, the battery output insufficiency determination unit 32 stores multiple mappings for each SOH, based on SOC and battery temperature Btmp, to determine the value (State of Power, hereinafter referred to as SOP) that the drive battery 10 can output. Figure 3 As indicated by the arrow, when the drive battery 10 is in a new condition (e.g., SOH = 100%), with an SOP of 15 kW, an SOC of 20%, and a battery temperature Btmp of -20°C, the drive battery 10 is in a deteriorated condition (e.g., SOH = 30%). With an SOP of 15 kW, an SOC of 20%, and a battery temperature Btmp of 0°C, the drive battery 10 is in a deteriorated condition.

[0072] In this way, the battery output deficiency determination unit 32 acquires SOH and SOC, compares the acquired SOH and SOC with a three-dimensional mapping map, and acquires the battery temperature Btmp, which is the SOP (hereinafter referred to as the reference SOP) at which the battery output is determined to be reduced, from the three-dimensional mapping map. Here, the battery output deficiency determination unit 32 can also acquire the actual SOP (hereinafter referred to as the actual SOP). However, the actual SOP may be corrected based on the decrease in voltage Bv in order to suppress over-discharge prevention of the drive battery 10. Therefore, if the battery output deficiency determination unit 32 determines that the battery output is reduced by comparing the actual SOP with the reference SOP, it may not be able to make an accurate judgment. Therefore, by acquiring the battery temperature Btmp, which becomes the reference SOP, the battery output deficiency determination unit 32 can accurately and quickly determine the decrease in the upper limit power W2 of the drive battery 10. In addition, the battery output deficiency determination unit 32 can also determine the decrease in the upper limit power W2 of the battery based on the outside temperature, etc., instead of the battery temperature Btmp. Alternatively, the battery output deficiency determination unit 32 can also use the first predetermined temperature T1 as an extremely low temperature (e.g., -20°C), and without acquiring SOH and SOC, determine that the battery's upper limit power W2 has decreased if the temperature is below the first predetermined temperature T1. Furthermore, the battery output deficiency determination unit 32 can also determine the decrease in the battery's upper limit power W2 based on either SOH or SOC and a two-dimensional mapping graph representing the relationship between battery temperature Btmp and SOP. Alternatively, the battery's upper limit power W2 can also be calculated by the battery monitoring unit (BMU) 10a.

[0073] Furthermore, when the battery temperature Btmp is above the second predetermined temperature T2, the battery output deficiency determination unit 32 determines that there is a second power deficiency. More specifically, when the battery temperature Btmp is above the second predetermined temperature T2, the battery output deficiency determination unit 32 of the control device 20 suppresses the temperature rise of the drive battery 10 by suppressing the upper limit power W2 of the battery. As a result, the second power that can be supplied from the drive battery 10 to each motor is reduced. When the upper limit power W2 of the battery is suppressed while the drive battery 10 is in a high-temperature state, the battery output deficiency determination unit 32 determines that there is a second power deficiency.

[0074] Furthermore, the battery output insufficiency determination unit 32 acquires the speed V, and if the speed V is above the first predetermined speed Vt, it determines that there is a second power shortage. That is, when the electric vehicle 1 is traveling at high speed, the energy required for acceleration increases. Therefore, when the speed is above the first predetermined speed Vt, more first power and second power are required compared to when the speed is below the first predetermined speed Vt. Therefore, by determining that there is a second power shortage when the speed is above the first predetermined speed Vt, the battery output insufficiency determination unit 32 can supply first power to each motor as quickly as possible. That is, even if the battery upper limit power W2 has not decreased and it is determined that the battery upper limit power W2 has not been suppressed, the battery output insufficiency determination unit 32 still determines that there is a second power shortage when the speed is above the first predetermined speed Vt.

[0075] The power generation control unit 34 controls the internal combustion engine 2 and the generator 4 based on the target power generation W1 calculated by the drive shaft torque calculation unit 30a and the power conversion calculation unit 30d. Here, the target power generation W1 is the target value of the first power that the generator 4 needs to supply to each electric motor. In this embodiment, in order to generate the target power generation W1 by driving the generator 4 with the internal combustion engine 2, the power generation control unit 34 calculates the engine torque ETq required by the internal combustion engine 2 in each calculation unit described later.

[0076] The power generation control unit 34 includes: a power calculation unit 34a, a target engine speed calculation unit 34b, an engine torque calculation unit 34c, and a generator torque calculation unit 34d. The power calculation unit 34a calculates the target power generation GW required from the generator 4 based on the target power generation W1, taking into account transmission losses incurred when supplying first power from the generator 4 to each motor. Transmission losses can also be calculated based on a mapping diagram recording the relationship between the generator 4's power generation and transmission losses. Furthermore, the target power generation GW can also be calculated considering the power required to charge the drive battery 10, the power required by other electric vehicle 1 equipment, and the upper limit of power generation for protecting each motor.

[0077] The target engine speed calculation unit 34b acquires the target power generation GW and calculates the target engine speed (target speed) Ert, which is the target value for the speed at which the internal combustion engine 2 drives the generator 4, based on the target power generation GW. At this time, the target engine speed calculation unit 34b can also refer to a mapping diagram recording the fuel injection quantity and ignition timing of the internal combustion engine 2, and calculate the target engine speed Ert in a way that optimizes the fuel economy of the internal combustion engine 2. As a result, the fuel economy of the electric vehicle 1 is improved. Furthermore, the target engine speed calculation unit 34b can also acquire the speed V and calculate the target engine speed Ert corresponding to the speed V. Therefore, when the electric vehicle 1 accelerates, it is possible to prevent the speed of the internal combustion engine 2 from becoming excessively high relative to the speed V.

[0078] The power generation control unit 34 sets a lower limit value minErt for the target engine speed Ert. Furthermore, when the driving mode control unit 30 switches to series mode and the battery output deficiency judgment unit 32 determines that there is a second power shortage, the power generation control unit 34 performs correction control of the internal combustion engine 2 by adjusting the lower limit value minErt to a larger value (as described in the following specification and...). Figure 8 In this context, the correction control is denoted as the lower limit correction control. For example... Figure 4 As shown, the lower limit value minErt is the target engine speed Ert from time T0 when the accelerator pedal 21 is not pressed to time T1. In this embodiment, the target engine speed calculation unit 34b acquires the target engine speed Ert and sets an initial value for the lower limit value minErt. The initial value may also be a pre-stored value. When the battery output insufficiency judgment unit 32 determines that there is a second power shortage, the target engine speed calculation unit 34b performs a correction calculation to correct the lower limit value minErt of the target engine speed Ert to a value greater than the initial value (see reference). Figure 4 During calibration (Ert).

[0079] Furthermore, the target engine speed calculation unit 34b can also acquire the target engine speed Ert and speed V, and perform correction calculations to set the lower limit value minErt of the target engine speed Ert to a value larger than the initial value if the speed V is higher. As a result, the first power supplied from the generator 4 to each electric motor increases rapidly. Therefore, the acceleration performance of the electric vehicle 1 is improved. In addition, the higher the speed V of the electric vehicle 1, the easier it is to quickly reach the high speed of the actual engine speed Erq (described later). On the other hand, when the speed V is low, the actual engine speed Erq (described later) becomes low, thus reducing the noise and vibration caused by the rotation of the internal combustion engine 2.

[0080] When the target power generation GW increases based on the target power generation W1, the power generation control unit 34 sets a limit value dErtLim for the increase rate of the target engine speed Ert. When the driving mode control unit 30 switches to series mode and the battery output insufficiency judgment unit 32 determines that there is a second power shortage, the power generation control unit 34 performs correction control of the internal combustion engine 2 by adjusting the increase rate limit value dErtLim to a larger value (as described in the following specification and...). Figure 8 In this context, the correction control is denoted as the limit value correction control. The increase rate limit value dErtLim is the upper limit of the rate of change of the target engine speed Ert per unit time when the accelerator pedal 21 is depressed. That is, in Figure 4 In this context, it represents the upper limit of the slope of the target engine speed Ert from time T1 to time T2.

[0081] In this embodiment, the target engine speed calculation unit 34b sets a limit value dErtLim for the rate of increase of the target engine speed Errt. The target engine speed calculation unit 34b sets an initial value (first limit value) for the rate of increase limit value dErtLim from time T1 to time T2. The initial value may also be a pre-stored value. The target engine speed calculation unit 34b performs a correction calculation to correct the rate of increase limit value dErtLim to a second limit value greater than the initial value. As a result, the power generation control unit 34 can quickly increase the actual engine speed Erq (described later). Therefore, the actual engine speed Erq (described later) can easily and quickly reach a higher speed. Consequently, the generator 4 can supply first power to each electric motor more quickly, and the acceleration of the electric vehicle 1 improves.

[0082] Furthermore, in this embodiment, the target engine speed calculation unit 34b lowers the second limit value as the target engine speed Ert increases. For example... Figure 4 and Figure 5 As shown, for example, during the period from 4000 rpm to 5000 rpm, the target engine speed Ert (DertLim) is corrected by setting the second limit value of the increase rate limit value dErtLim to be lower than 4000 rpm. Figure 4 During the correction, Ert increases slowly. This makes it easier to suppress excessive increases in the actual engine speed Erq, as described later.

[0083] Furthermore, the target engine speed calculation unit 34b can also set a smaller second limit value for the case where the temperature of the drive battery 10 is high compared to the case where the temperature of the drive battery 10 is low. More specifically, such as Figure 5 As shown, the rate of increase limit dErtLim when the battery temperature Btmp is above the second specified temperature T2 is a smaller value than the rate of increase limit dErtLim when the battery temperature Btmp is below the first specified temperature T1. That is, even if the outside temperature is normal (approximately 10°C to 25°C), the battery temperature Btmp may still be above the second specified temperature T2. Therefore, the frequency with which the battery temperature Btmp is above the second specified temperature T2 is more frequent than the frequency with which the battery temperature Btmp is below the first specified temperature T1. The target engine speed calculation unit 34b sets the rate of increase limit dErtLim to a smaller value when the drive battery 10, which generates power at a higher frequency, is in a high-temperature state compared to when the drive battery 10 is in a low-temperature state. As a result, the speed of the internal combustion engine 2 increases slowly. Consequently, noise and vibration caused by the rotation of the internal combustion engine 2 can be reduced. On the other hand, when the drive battery 10 is in a low-temperature state, the speed of the internal combustion engine 2 increases rapidly compared to when the drive battery 10 is in a high-temperature state.

[0084] The engine torque calculation unit 34c acquires the target power generation GW and the target engine speed Ert, and calculates the engine torque ETq required by the internal combustion engine 2 based on the target power generation GW and the target engine speed Ert. More specifically, the engine torque calculation unit 34c calculates the engine torque ETq1 by dividing the target power generation GW by the target engine speed Ert, and adds the torque required to change the speed of the internal combustion engine 2 when necessary, thus calculating the engine torque ETq. The engine torque calculation unit 34c sends the engine torque ETq to the engine control unit 2a. The engine control unit 2a calculates the actual engine torque ETqr based on the actual engine speed (actual speed) Erq acquired from various sensors such as the crank angle sensor (not shown) of the internal combustion engine 2. The engine control unit 2a acquires the engine torque ETq and controls the internal combustion engine 2 such that the actual engine torque ETqr becomes the engine torque ETq. At this time, the engine control unit 2a sends the actual engine speed Erq to the engine torque calculation unit 34c. The engine torque calculation unit 34c obtains the actual engine speed Erq and corrects the engine required torque ETq by using the target engine speed Ert.

[0085] The generator torque calculation unit 34d acquires the engine required torque ETq and calculates the target load torque LTq, which is the target load torque of the generator 4, based on the engine required torque ETq. More specifically, the generator torque calculation unit 34d calculates the target load torque LTq by adding or subtracting the torque used to change the speed of the internal combustion engine 2 from the load torque LTq1 that corresponds to the engine required torque ETq. The generator torque calculation unit 34d can also calculate the target load torque LTq based on a mapping diagram that records the relationship between the engine required torque ETq and the target load torque LTq. The generator torque calculation unit 34d sends the target load torque LTq to the generator control device 4a. The generator control device 4a detects the actual power generation GWr, which is the actual power generation of the generator 4, and the speed of the generator 4, calculates the actual load torque LTqr based on the actual power generation GWr and the speed of the generator 4, and controls the generator 4 in such a way that the actual load torque LTqr becomes the target load torque LTq. In addition, the generator control device 4a sends the actual power generation GWr to the engine torque calculation unit 34c via the generator torque calculation unit 34d.

[0086] The power generation control unit 34 includes a first control mode and a second control mode. When the driving mode control unit 30 switches to series mode, the battery output deficiency judgment unit 32 determines a second power deficiency, and the throttle opening Th is above a predetermined opening Tht, the power generation control unit 34 switches from the second control mode to the first control mode. That is, regardless of the driver's acceleration request, the power generation control unit 34 switches from the second control mode to the first control mode when the battery's maximum power W2 decreases. Alternatively, the power generation control unit 34 may switch from the second control mode to the first control mode when the actual power generation GWr is less than the target power generation GW, i.e., when the actual power generation GWr is insufficient relative to the target power generation GW.

[0087] In the first control mode, the power generation control unit 34 controls the internal combustion engine 2 to change the actual engine speed Erq of the internal combustion engine 2. More specifically, in the first control mode, the power generation control unit 34 calculates the engine required torque ETq, which includes the rotational torque UTq required to increase the target engine speed Ert. That is, the engine torque calculation unit 34c calculates the engine required torque ETq by adding the rotational torque UTq to the engine torque ETq1 obtained based on the target power generation GW. The rotational torque UTq is a torque preset for each target engine speed Ert, taking into account the frictional losses between the internal combustion engine 2 and the generator 4, the inertial forces of the crankshaft of the internal combustion engine 2 and the rotating shaft of the generator 4, etc.

[0088] On the other hand, in the second control mode, the power generation control unit 34 controls the generator 4 to change the actual engine speed Erq of the internal combustion engine 2. More specifically, in the second control mode, the power generation control unit 34 calculates the target load torque LTq, which includes the rotational rising torque UTq. That is, the generator torque calculation unit 34d calculates the target load torque LTq by subtracting the rotational rising torque UTq from the load torque LTq1 that corresponds to the engine required torque ETq.

[0089] Thus, in the first control mode, the internal combustion engine 2 itself increases the actual engine speed Erq, thereby increasing the intake air volume and fuel injection volume of the internal combustion engine 2 compared to the second control mode. As a result, the fuel economy of the internal combustion engine 2 deteriorates in the first control mode. However, since the power generation of the generator 4 does not decrease, the first power supplied from the generator 4 to each electric motor does not decrease. As a result, the acceleration performance of the electric vehicle 1 improves.

[0090] On the other hand, in the second control mode, since the generator torque calculation unit 34d subtracts the rotational rise torque UTq, the actual power generation of generator 4 GWr decreases. However, because generator 4 reduces the actual power generation GWr, internal combustion engine 2 maintains output, and the actual engine speed Erq of internal combustion engine 2 increases. As a result, the fuel economy of internal combustion engine 2 is maintained. Furthermore, in the case of a decrease in the target engine speed Ert, in the second control mode, the actual engine speed Erq decreases by increasing the target load torque LTq.

[0091] In addition, such as Figure 6 and Figure 7 As shown, in this embodiment, the power generation control unit 34 suppresses the rotational torque UTq based on the actual engine speed Erq in the first control mode. More specifically, the power generation control unit 34 can also suppress the rotational torque UTq when the actual engine speed Erq is greater than the target engine speed Errt. That is, as Figure 6 As shown, the deviation (difference) between the target engine speed Ert and the actual engine speed Erq is calculated. A smaller deviation indicates a decrease in the rotational torque UTq. Figure 6 The graph showing the relationship between the rotational torque UTq and the difference indicates that when the deviation is less than 300 rpm, the value of the rotational torque UTq is reduced, and when the deviation is below zero, the rotational torque UTq is set to zero. This helps to suppress excessive increases in the actual engine speed Erq.

[0092] Furthermore, the power generation control unit 34 can also suppress the rotational torque UTq as the actual engine speed Erq increases. That is, as... Figure 7 As shown, when the actual engine speed Erq is, for example, 4000 rpm or higher, the power generation control unit 34 reduces the rotational torque UTq as the actual engine speed Erq increases. Even in this case, it is possible to suppress excessive increase in the actual engine speed Erq.

[0093] Next, use Figure 8 The flowchart below explains the control sequence of the power generation control unit 34 and the battery output deficiency judgment unit 32 of the control device 20 in this embodiment. The power generation control unit 34 starts its control operation when the ignition switch (not shown) is turned on. Furthermore, the power generation control unit 34 starts its control operation in the second control mode.

[0094] In S1, the power generation control unit 34 determines whether the driving mode has been switched to series mode by the driving mode control unit 30. If the power generation control unit 34 of the control device 20 determines that the driving mode has been switched to series mode (S1 is yes), the process proceeds to S2.

[0095] S2 to S4 represent the processing performed by the battery output deficiency determination unit 32. In S2 to S4, the battery output deficiency determination unit 32 determines whether the second power is insufficient. In S2, the battery output deficiency determination unit 32 determines whether the battery temperature Btmp is below the first predetermined temperature T1. If the battery temperature Btmp is greater than the first predetermined temperature T1 (S2 No), the battery output deficiency determination unit 32 proceeds to S3. On the other hand, if the battery temperature Btmp is below the first predetermined temperature T1 (S2 Yes), the battery output deficiency determination unit 32 determines that the second power is insufficient and sends the determination result to the power generation control unit 34. The power generation control unit 34 obtains the determination result from the battery output deficiency determination unit 32 and proceeds to S10.

[0096] In S10, the power generation control unit 34 performs lower limit correction control. The power generation control unit 34 acquires the speed V (km / h) and performs lower limit correction control such that the lower limit value minErt of the target engine speed Ert is set to a larger value as the speed V increases. For example, if the initial value of the lower limit value minErt is 0 rpm, it can be corrected to 1000 rpm. Furthermore, as the speed V increases, the power generation control unit 34 can appropriately correct the lower limit value minErt to a value greater than 1000 rpm. In addition, in the second control mode, the power generation control unit 34 uses the initial value of the lower limit value minErt (refer to...). Figure 4 When the power generation control unit 34 performs lower limit correction control, it initiates the processing step S5.

[0097] In S3, the battery output deficiency determination unit 32 determines whether the battery temperature Btmp is above the second predetermined temperature T2. If the battery output deficiency determination unit 32 determines that the battery temperature Btmp is below the second predetermined temperature T2 (S3 No), the process proceeds to S4. On the other hand, if the battery output deficiency determination unit 32 determines that the battery temperature Btmp is above the second predetermined temperature T2 (S3 Yes), it determines that there is a second power deficiency and sends the determination result to the power generation control unit 34. The power generation control unit 34 receives the determination result from the battery output deficiency determination unit 32 and the process proceeds to S5.

[0098] In step S4, the battery output deficiency determination unit 32 acquires the speed V of the electric vehicle 1 and determines whether the speed V is greater than or equal to Vt. If the battery output deficiency determination unit 32 determines that the speed V is greater than or equal to Vt (S4 Yes), it determines that there is a second power deficiency and sends the determination result to the power generation control unit 34. That is, if any one of the conditions from S2 to S4 is met, the battery output deficiency determination unit 32 determines that there is a second power deficiency. The power generation control unit 34 acquires the determination result of the battery output deficiency determination unit 32 and proceeds to step S5. On the other hand, if the battery output deficiency determination unit 32 determines that the speed V is less than Vt (S4 No), it determines that none of the conditions from S2 to S4 are met, and it determines that there is no second power deficiency. The battery output deficiency determination unit 32 sends the determination result to the power generation control unit 34. The power generation control unit 34 acquires the determination result of the battery output deficiency determination unit 32 and proceeds to step S5.

[0099] In S5, the power generation control unit 34 determines whether the throttle opening Th is greater than or equal to the specified opening Tht. If the power generation control unit 34 determines that the throttle opening Th is greater than or equal to the specified opening Tht (as in S4), the process proceeds to S6. In S6, the power generation control unit 34 switches from the second control mode to the first control mode. After switching to the first control mode, the power generation control unit 34 proceeds to S7. Furthermore, in S5, the power generation control unit 34 can also determine whether the actual power generation GWr is less than or equal to the target power generation GW. If the power generation control unit 34 determines that the actual power generation GWr is less than the target power generation GW, the process proceeds to S6.

[0100] In S7, the power generation control unit 34 determines whether the target engine speed Ert is increasing. If the power generation control unit 34 determines that the target engine speed Ert is increasing (S7 is yes), the process proceeds to S8. The target engine speed Ert is increasing when the accelerator pedal 21 is depressed, the driver requests an increase in torque DTq, the target power generation W1 also increases, and thus the target power generation GW increases. That is, the electric vehicle 1 is in an acceleration state. The power generation control unit 34 can also determine that the target engine speed Ert is increasing when the accelerator opening Th is above the specified opening Tht. That is, the power generation control unit 34 can also determine whether the target engine speed Ert is increasing in S5. In addition, it can also determine that the target engine speed Ert is increasing when the actual power generation GWr is less than the target power generation GW.

[0101] In S8, the power generation control unit 34 performs limit value correction control. For example, if the initial value of the increase rate limit value dErtLim is 20%, the power generation control unit 34 can correct it by setting the increase rate limit value dErtLim to a value greater than 20%. Furthermore, in the second control mode, the initial value of the increase rate limit value dErtLim is used. When limit value correction control is performed in S7, the process proceeds to S9.

[0102] In S9, the power generation control unit 34 obtains the throttle opening Th from the throttle opening determination unit 36 ​​and determines whether the throttle opening Th is zero (throttle cut-off). If the power generation control unit 34 determines that the throttle is cut-off (S9 is), it simultaneously ends the lower limit correction and the increase rate limit correction, and proceeds to S11. In S11, the power generation control unit 34 switches from the first control mode to the second control mode, and proceeds to S1.

[0103] If the power generation control unit 34 determines that it is not in series mode (S1 No), it returns the process to before S1. If it determines that the throttle opening Th is less than the specified opening Tht (S5 No), it enters S11, maintains the second control mode, and returns the process to before S1.

[0104] If the power generation control unit 34 determines that the target engine speed Ert has not increased (S7 No) and that the throttle has not been cut off (S9 No), it returns the processing to before S5. Thus, the first control mode is maintained until the throttle opening Th is less than the specified opening Tht.

[0105] Next, with reference to the accompanying drawings, the control device 220 of the electric vehicle 201 according to the second embodiment of the present invention will be described. Furthermore, the system structure of the electric vehicle 1 and the control device 220 in the second embodiment is the same as that in the first embodiment, therefore, the description is omitted. In addition, regarding the control performed by the control device 220 in the second embodiment, only the points that differ from the control in the first embodiment will be described.

[0106] In the control device 220 of the second embodiment, the power generation control unit 234 sets an upper limit value maxErt in addition to the lower limit value minErt of the target engine speed Ert, which is different from the control device 20 in the first embodiment.

[0107] like Figure 9 As shown in the timing diagram of this embodiment, an example is illustrated where the battery temperature Btmp, as measured by the battery temperature acquisition unit 32a, rises in stages, indicating a second power deficiency. (As shown from...) Figure 9As shown from time 0 to time A, the battery temperature Btmp increases along with the speed V of the electric vehicle 201. During the period from time 0 to time A, the target engine speed Ert increases by a first limit value of the increase rate limit dErtLim. When time A is exceeded, the speed V decreases towards time B, and the driving mode is switched to series mode by the driving mode control unit 30. On the other hand, the battery temperature Btmp does not decrease between time A and time B. At time B, when the battery temperature Btmp reaches or exceeds the second predetermined temperature T2, the battery output insufficiency judgment unit 32 determines that there is a second power shortage.

[0108] When the driving mode control unit 30 switches to series mode and the battery output deficiency judgment unit 32 determines that there is a second power deficiency, the power generation control unit 234 performs correction increase rate limit value dErtLim limit value correction control (see reference). Figure 9 (The limit value correction control is turned on). In addition to limit value correction control, the power generation control unit 234 can also perform at least one of lower limit value correction control and switching from the second control mode to the first control mode.

[0109] from Figure 9 The time interval from time C to time D shows the state where the accelerator pedal 21 is pressed again by the user of the electric vehicle 201. During this period, the battery temperature Btmp does not decrease and continues to maintain the series mode. In this situation, the power generation control unit 234 performs vibration / noise reduction control (hereinafter referred to as NV reduction control. NV is an abbreviation for Noise, Vibration). More specifically, the power generation control unit 234 limits the upper limit value maxErt to below a specified speed R1. As shown in the graph of the target engine speed Ert from time C to time D, the power generation control unit 234 uses a second limit value greater than the first limit value for the increase rate limit value dErtLim to increase the target engine speed Ert until the target engine speed Ert reaches the specified speed R1. Thus, the power generation control unit 234 achieves the suppression of the deterioration of the fuel economy and the improvement of the acceleration performance of the electric vehicle 201, and suppresses the deterioration of vibration / noise accompanying the increase of the internal combustion engine 2 speed.

[0110] Here, the specified speed R1 can also be the point of change in the output characteristics of the internal combustion engine 2. Figure 10 This is a graph representing the output characteristics of internal combustion engine 2. For example... Figure 10As shown, the maximum output of the internal combustion engine 2 maintains a roughly constant slope up to a specified speed R1. When the specified speed R1 is exceeded, the slope of the maximum engine output decreases. The power generation control unit 234 uses a second limit value as the increase rate limit value dErtLim up to the specified speed R1 to increase the target engine speed Ert. Therefore, the power generation control unit 234 can efficiently utilize the output of the internal combustion engine 2 and quickly supply first power to the electric motor.

[0111] In addition, such as Figure 9 As shown in time B to C, when the target engine speed Ert is above the specified speed R1, if the battery output insufficient judgment unit 32 determines that there is a second power shortage, the power generation control unit 234 waits for the target engine speed Ert to reach the specified speed R1, and then executes NV reduction control.

[0112] like Figure 9 As shown in the diagram from time D to time E, when the speed V of the electric vehicle 201 is less than the second predetermined speed V2, the power generation control unit 234 limits the target engine speed Ert to below a predetermined speed R1. In this embodiment, during the period from time D to time E, the speed V of the electric vehicle 201 continuously increases. During this period, the power generation control unit 234 limits the upper limit value maxErt of the target engine speed Ert by maintaining it at the predetermined speed R1.

[0113] Furthermore, during the interval from time C to time E, the target engine speed Ert rises rapidly due to the high increase rate limit dErtLim, resulting in a rapid increase in the actual engine speed Erq. On the other hand, if the actual engine speed Erq of the internal combustion engine 2 is higher than the speed V of the electric vehicle 201, the user of the electric vehicle 201 may experience a sense of unease due to excessive vibration / noise, or a feeling that the electric vehicle 201 is idling (idling sensation). However, when the speed is below the second predetermined speed V2, the power generation control unit 234 limits the upper limit of the target engine speed Ert, maxErt, to a predetermined speed R1, thus making it difficult to experience such unease. Moreover, from time D to time E, the power generation control unit 234 maintains the target engine speed Ert during the period when the speed V of the electric vehicle 201 increases. Therefore, the power generation control unit 234 is able to suppress the unease caused by the rapid decrease in the actual engine speed Erq.

[0114] like Figure 9As shown from time E to time F, when the speed V of the electric vehicle 201 decreases from above the second predetermined speed V2 to below the third predetermined speed V3, the power generation control unit 234 moderates the upper limit value maxErt as the speed V increases. The third predetermined speed V3 is a value higher than the second predetermined speed V2. In this embodiment, the power generation control unit 234 refers to a mapping diagram in which the upper limit value maxErt of the target engine speed Ert increases in stages as the speed V increases. The power generation control unit 234 moderates the upper limit value maxErt by increasing the upper limit value maxErt of the target engine speed Ert according to the speed V. As a result, the actual power generation GWr also increases corresponding to the increase in speed V. Consequently, the feeling of idling is suppressed and insufficient battery output is compensated, thereby improving the acceleration performance of the electric vehicle 201.

[0115] like Figure 9 As shown after time F, when the speed reaches or exceeds the third predetermined speed V3, the power generation control unit 234 releases the upper limit limit of maxErt. In this embodiment, the speed V of the electric vehicle 201 also increases after time F, so the power generation control unit 234 maintains the target engine speed Ert at the maximum speed Rmax, which is the maximum value of the target engine speed Ert. Then, when the accelerator pedal 21 is released and the electric vehicle 201 decelerates, the power generation control unit 234 reduces the target engine speed Ert. When the final target engine speed Ert is lower than the predetermined speed R1, the power generation control unit 234 terminates the NV reduction control.

[0116] As explained above, the control devices 20 and 220 of the electric vehicles 1 and 201 according to the present invention can simultaneously suppress the deterioration of fuel economy and improve acceleration performance of the electric vehicles 1 and 201.

[0117] <Other Implementation Methods>

[0118] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. In particular, the various modifications described in this specification can be arbitrarily combined as needed.

[0119] (a) In the first embodiment described above, the power generation control unit 34 switches to the first control mode when it determines that the throttle opening Th is above a predetermined opening Tht. However, the present invention is not limited thereto. When the battery output insufficiency determination unit 32 determines that there is a second power shortage in S2 to S4, the power generation control unit 34 can also obtain the determination result and immediately switch to the first control mode.

[0120] (b) In the first embodiment described above, an example was given of the power generation control unit 34 performing lower limit correction control before switching to the first control mode when the drive battery 10 is below the first predetermined temperature T1 in S2 (S2 is), but the present invention is not limited thereto. Lower limit correction control may also be performed after switching to the first control mode.

[0121] (c) In the first embodiment described above, an example was given where, when the battery output deficiency determination unit 32 determines that there is a second power deficiency, the power generation control unit 34 performs lower limit correction control, switches to the first mode, and performs limit correction control. However, the present invention is not limited to this. Alternatively, even when the battery output deficiency determination unit 32 determines that there is a second power deficiency, if the user of the electric vehicle 1 selects the energy-saving mode, the power generation control unit 34 may not perform any one or all of the lower limit correction control, switching to the first mode, and limit correction control. Thus, in the energy-saving mode, fuel economy can be prioritized. Furthermore, the power generation control unit 34 may also have a selection unit that allows the user of the electric vehicle 1 to select any one of the lower limit correction control, switching to the first mode, and limit correction control. Thus, the user can selectively prioritize either acceleration or fuel economy. Additionally, the power generation control unit 34 may be linked to the navigation system of the electric vehicle 1, so that when the electric vehicle 1 is traveling in a residential area, lower limit correction control is not performed. Thus, the electric vehicle 1 can travel quietly in residential areas.

[0122] (d) In the first and second embodiments described above, the electric vehicles 1 and 201 were described as four-wheel drive hybrid vehicles, but the present invention is not limited thereto. The electric vehicles 1 and 201 can be plug-in hybrid vehicles, and may also have a power supply function that supplies power from the drive battery 10 to external machines (such as home appliances).

[0123] Symbol Explanation

[0124] 1, 201: Electric vehicles; 2: Internal combustion engines; 4: Generators

[0125] 6: Front motor, 8: Rear motor, 10: Drive battery

[0126] 12a: Front drive axle, 14a: Rear drive axle, 20, 220: Control unit

[0127] 21: Accelerator pedal; 21a: Accelerator position sensor

[0128] 30: Driving mode control unit; 32: Battery output insufficiency judgment unit

[0129] 32a: Battery temperature acquisition unit; 34, 234: Power generation control unit

[0130] 36: Throttle opening judgment unit, Btmp: Battery temperature

[0131] Ert: Target engine speed (target RPM), Erq: Actual engine speed (actual RPM)

[0132] GW: Target power generation, GWr: Actual power generation

[0133] T: Specified temperature, V: Speed

[0134] minErt: Lower limit value, dErtLim: Increase rate limit value

Claims

1. A control device for an electric vehicle, comprising: an internal combustion engine mounted on the electric vehicle, a generator driven by the internal combustion engine, an electric motor driving a drive shaft of the electric vehicle, and a drive battery supplying power to the electric motor, characterized in that, have: The driving mode control unit switches to a series mode, which enables the electric vehicle to drive by a first power source and a second power source. The first power source is supplied from the generator to the motor, and the second power source is supplied from the drive battery to the motor. A battery output deficiency determination unit determines whether the second power is insufficient; and A power generation control unit, which controls the internal combustion engine and the generator based on the first power supply, The power generation control unit includes: A first control mode, wherein the first control mode controls the internal combustion engine to change the speed of the internal combustion engine; and A second control mode is used to control the generator to change the speed of the internal combustion engine. When the driving mode control unit switches to the series mode and the battery output deficiency determination unit determines that the second power is insufficient, the power generation control unit switches from the second control mode to the first control mode. The power generation control unit calculates the target speed based on the first power and sets a lower limit value for the target speed, which is the target speed of the internal combustion engine. When the driving mode control unit switches to the series mode and the battery output insufficiency judgment unit determines that the second power is insufficient, the power generation control unit performs correction control to increase the lower limit value.

2. The control device for an electric vehicle according to claim 1, characterized in that, The higher the speed of the electric vehicle, the larger the lower limit value will be adjusted by the power generation control unit.

3. The control device for an electric vehicle according to claim 1 or 2, characterized in that, The power generation control unit calculates the target speed based on the first power, which is the target speed of the internal combustion engine. When the target speed increases, the power generation control unit calculates the rate of increase of the target speed and sets a first limit value for the rate of increase. When the driving mode control unit switches to the series mode and the battery output insufficiency judgment unit determines that the second power is insufficient, the power generation control unit performs correction control to correct the rate of increase to a second limit value greater than the first limit value.

4. A control device for an electric vehicle, comprising: an internal combustion engine mounted on the electric vehicle, a generator driven by the internal combustion engine, an electric motor driving a drive shaft of the electric vehicle, and a drive battery supplying power to the electric motor, characterized in that, have: The driving mode control unit switches to a series mode, which enables the electric vehicle to drive by a first power source and a second power source. The first power source is supplied from the generator to the motor, and the second power source is supplied from the drive battery to the motor. A battery output deficiency determination unit determines whether the second power is insufficient; and A power generation control unit, which controls the internal combustion engine and the generator based on the first power supply, The power generation control unit includes: A first control mode, wherein the first control mode controls the internal combustion engine to change the speed of the internal combustion engine; and A second control mode is used to control the generator to change the speed of the internal combustion engine. When the driving mode control unit switches to the series mode and the battery output deficiency determination unit determines that the second power is insufficient, the power generation control unit switches from the second control mode to the first control mode. The power generation control unit calculates the target speed based on the first power, which is the target speed of the internal combustion engine. When the target speed increases, the power generation control unit calculates the rate of increase of the target speed and sets a first limit value for the rate of increase. When the driving mode control unit switches to the series mode and the battery output insufficiency judgment unit determines that the second power is insufficient, the power generation control unit performs correction control to correct the rate of increase to a second limit value greater than the first limit value.

5. The control device for an electric vehicle according to claim 4, characterized in that, The second limit value is a value that decreases as the target rotational speed increases.

6. The control device for an electric vehicle according to claim 1 or 4, characterized in that, The insufficient battery output determination unit includes a battery temperature acquisition unit, which acquires the temperature of the drive battery. If the temperature obtained by the battery temperature acquisition unit is below the first specified temperature or above the second specified temperature, the battery output insufficiency determination unit determines that the second power is insufficient.

7. The control device for an electric vehicle according to claim 4, characterized in that, The insufficient battery output determination unit includes a battery temperature acquisition unit, which acquires the temperature of the drive battery. If the temperature obtained by the battery temperature acquisition unit is below a first predetermined temperature or above a second predetermined temperature, the battery output insufficiency determination unit determines that the second power is insufficient. The second limit value is as follows: compared to the case where the temperature of the drive battery obtained by the battery output deficiency determination unit is below the first predetermined temperature, the value of the second limit value is smaller when the temperature of the drive battery obtained by the battery output deficiency determination unit is above the second predetermined temperature.

8. The control device for an electric vehicle according to claim 1 or 4, characterized in that, The power generation control unit calculates the rotational torque that increases the speed of the internal combustion engine. The power generation control unit acquires the actual rotational speed, which is the actual rotational speed of the internal combustion engine. In the first control mode, the power generation control unit suppresses the rotational upward torque based on the actual rotational speed.

9. The control device for an electric vehicle according to claim 8, characterized in that, When the actual rotational speed is greater than the target rotational speed, the power generation control unit suppresses the rotational increase torque.

10. The control device for an electric vehicle according to claim 8, characterized in that, The power generation control unit suppresses the rotational torque as the actual rotational speed increases.

11. The control device for an electric vehicle according to claim 1 or 4, characterized in that, It also includes a throttle opening determination unit, which determines the throttle opening. When the throttle opening is zero, the power generation control unit switches from the first control mode to the second control mode.

12. The control device for an electric vehicle according to claim 1 or 4, characterized in that, When the speed of the electric vehicle is above a first predetermined speed, the battery output insufficiency determination unit determines that the second power is insufficient.

13. The control device for an electric vehicle according to claim 6, characterized in that, The first specified temperature is calculated based on either or both of the degradation of the driving battery and the charging rate of the driving battery.

14. The control device for an electric vehicle according to claim 1 or 4, characterized in that, The power generation control unit calculates the target power generation based on the first power supply and obtains the actual power generation. The target power generation is the power generation target for the generator, and the actual power generation is the actual power generation of the generator. If the actual power generation is less than the target power generation, the power generation control unit switches from the second control mode to the first control mode.

15. The control device for an electric vehicle according to claim 1 or 4, characterized in that, The power generation control unit calculates the target speed based on the first power and sets an upper limit value for the target speed, which is the target speed of the internal combustion engine. When the driving mode control unit switches to the series mode and the battery output insufficiency judgment unit determines that the second power is insufficient, the power generation control unit limits the upper limit value to below the specified speed.

16. The control device for an electric vehicle according to claim 15, characterized in that, The specified speed is the point at which the output characteristics of the internal combustion engine change.

17. The control device for an electric vehicle according to claim 15, characterized in that, When the speed of the electric vehicle is less than the second predetermined speed, the power generation control unit limits the upper limit to below the predetermined speed.

18. The control device for an electric vehicle according to claim 15, characterized in that, When the speed of the electric vehicle is above the second predetermined speed, the power generation control unit increases the upper limit value as the speed increases.

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