Control device for hybrid vehicle

Abstract

To provide a control device for a hybrid vehicle capable of appropriately charging a high-voltage power supply and a low-voltage power supply under conditions where engine output is limited.SOLUTION: There is provided a control device for a hybrid vehicle, the hybrid vehicle comprising: a motor configured to be capable of converting power of an engine into electric power and charge the generated power into a main power supply; and an alternator configured to convert the power of the engine into electric power and charge the generated power into an auxiliary power supply. When a required power of the engine based on a required driving power of the hybrid vehicle, a required generated power of the motor, and a required generated power of the alternator is equal to or greater than a predetermined upper limit power, the control device limits the generated power of the motor (step S3). When the required power of the engine is equal to or greater than the upper limit power and a charge remaining amount of the main power supply is equal to or less than a predetermined first remaining amount, the control device limits the generated power of the alternator to power which makes the charge remaining amount of the auxiliary power supply equal to or greater than a predetermined second remaining amount, and increases the generated power of the motor (step S5).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle equipped with an engine and a motor as driving power sources, and more particularly to a control device for a hybrid vehicle further equipped with an alternator for converting the power of the engine into electric power.

Background Art

[0002] Patent Document 1 describes a control device for a hybrid vehicle including a motor-generator and an alternator connected to the output shaft of an engine, a high-voltage battery for charging the electric power generated by the motor-generator, and a low-voltage battery for charging the electric power generated by the alternator. When there is a request to charge the low-voltage battery, specifically when the vehicle is stopped, this control device rotates the output shaft of the engine by driving the motor-generator while fuel-cutting the engine, generates electricity with the alternator to charge the low-voltage battery. When there is a request to charge both the high-voltage battery and the low-voltage battery, it drives the engine, generates electricity with the motor-generator to charge the high-voltage battery, and generates electricity with the alternator to charge the low-voltage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The control device described in Patent Document 1 is configured to charge a high-voltage battery and a low-voltage battery when the vehicle is stopped and in a situation where sufficient power can be output from the engine. However, when the vehicle is running, in addition to charging the high-voltage battery and the low-voltage battery, power for generating the required driving force is output from the engine. On the other hand, when the vehicle is running, the output of the engine may be limited due to abnormal noise, vibration, or driving environment. Patent Document 1 does not disclose the control of the motor generator and the alternator under the condition that the output of the engine is limited. Therefore, there is room for technical improvement to appropriately control the generated power of the motor generator and the alternator.

[0005] The present invention has been made paying attention to the above technical problems, and an object thereof is to provide a control device for a hybrid vehicle capable of appropriately charging a high-voltage power source and a low-voltage power source under the condition that the output of the engine is limited.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention provides a control device for a hybrid vehicle including a motor configured to convert the power of the engine into electric power and charge the generated electric power into a main power source, and an alternator configured to convert the power of the engine into electric power and charge the generated electric power into an auxiliary power source. When the required power of the engine based on the required driving force of the hybrid vehicle, the required generated power of the motor, and the required generated power of the alternator is equal to or greater than a predetermined upper limit power, the generated power of the motor is limited. When the required power of the engine is equal to or greater than the upper limit power and the remaining charge amount of the main power source is equal to or less than a first predetermined remaining amount, the generated power of the alternator is limited to a power such that the remaining charge amount of the auxiliary power source is equal to or greater than a second predetermined remaining amount, and the generated power of the motor is increased.

Effects of the Invention

[0007] According to the present invention, when the required power of the engine is equal to or higher than the upper limit power, the generated power of the alternator can be ensured by restricting the generated power of the motor, and the auxiliary power supply can be appropriately charged. Further, when the required power of the engine is equal to or higher than the upper limit power and the remaining charge amount of the main power supply is equal to or less than the first predetermined remaining amount, the generated power of the alternator is restricted to a power at which the remaining charge amount of the auxiliary power supply becomes equal to or higher than the second predetermined remaining amount, and the generated power of the motor is increased. Therefore, while suppressing an excessive decrease in the remaining charge amount of the auxiliary power supply, the main power supply can be charged. That is, the power of the engine can be appropriately distributed to the driving force, the charging of the main power supply, and the charging of the auxiliary power supply, and while suppressing an excessive decrease in the charging power of each power supply, a decrease in the driving force can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples when the present invention is embodied, and do not limit the present invention.

[0010] An example of a hybrid vehicle according to an embodiment of the present invention is shown in FIG. 1. The hybrid vehicle (hereinafter simply referred to as a vehicle) Ve shown in FIG. 1 includes an engine (ENG) 1 and a motor (MG) 2 as driving power sources. This vehicle Ve is a front-engine rear-drive type vehicle in which the output shaft 3 of the engine 1 faces the front-rear direction of the vehicle Ve.

[0011] The engine 1 can be configured in the same manner as a gasoline engine or a diesel engine provided in a conventional vehicle, and controls the intake air amount and the fuel injection amount based on a required driving force according to the operation amount of an accelerator device (not shown) or the like, thereby generating driving torque.

[0012] A torque converter 4 is connected to the output shaft 3 of the engine 1. This torque converter 4 can be configured in the same manner as a torque converter provided in a conventional vehicle, and includes a pump impeller 5 connected to the output shaft 3 of the engine 1, a turbine runner 7 disposed opposite to the pump impeller 5 and having an output shaft 6 connected thereto, and a stator for rectifying the flow of oil from the pump impeller 5 toward the turbine runner 7. Note that the torque converter 4 may be provided with a lock-up clutch that connects the output shaft 3 of the engine 1 and the output shaft 6 of the torque converter 4 when the rotational speed difference between the pump impeller 5 and the turbine runner 7 becomes equal to or less than a predetermined difference.

[0013] A motor 2 configured to apply power to the output shaft 6 or to regenerate the power of the output shaft 6 is attached to the output shaft 6 of the torque converter 4. This motor 2, in addition to its function as a motor that generates driving torque when power is supplied, similar to a motor provided as a driving power source in a conventional electric vehicle or hybrid vehicle, can be configured by a motor-generator having a function as a generator that converts the power into electric power when its output shaft (rotor shaft) 8 is rotated. Specifically, it can be configured by a synchronous motor or an induction motor having a permanent magnet in the rotor.

[0014] Then, on the output shaft 8 of the motor 2, the left and right drive wheels 11r and 11l are connected via a transmission (T / M) 9 with a changeable gear ratio and a differential gear unit 10. Note that the transmission 9 may be constituted by a stepped transmission mechanism for stepwise changing the gear ratio, or may be constituted by a belt-type or toroidal transmission mechanism capable of continuously changing the gear ratio.

[0015] In addition, an alternator 12 that is rotated by the power of the engine 1 to generate electric power is provided in the engine 1 shown in FIG. 1. Specifically, the output shaft 3 of the engine 1 extends on the side opposite to the torque converter 4 and is configured such that torque is transmitted from the engine 1 to the alternator 12 via a belt transmission mechanism 13 provided at the tip thereof.

[0016] A high-voltage battery (high-voltage Batt) 14 constituted by a lithium-ion battery, a nickel-metal hydride battery, an all-solid-state battery, or the like is electrically connected to the above-described motor 2 via a power control unit (not shown) having an inverter and a converter. That is, power is supplied from the high-voltage battery 14 to the motor 2, and when the motor 2 functions as a generator, the power is configured to be charged into the high-voltage battery 14. Note that the high-voltage battery 14 corresponds to the "main power source" in the embodiment of the present invention.

[0017] In addition, a vehicle Ve shown in FIG. 1 is provided with a high-voltage electrical device 17 that uses high-voltage power such as a power outlet 15 to which AC100V is supplied and an air conditioner 16, similar to a household power source, and power is supplied to these high-voltage electrical devices 17 from the high-voltage battery 14.

[0018] Furthermore, an accessory battery (Auxiliary Batt) 18 configured in the same manner as the 12V battery provided in a conventional vehicle is electrically connected to the alternator 12, and the alternator 12 is configured to charge the accessory battery 18 with the electric power generated. This accessory battery 18 is configured to supply electric power to various lights provided in the vehicle Ve and low-voltage electrical devices 19 that operate with relatively low-voltage electric power such as a navigation system. Note that a high-voltage battery 14 is connected to the accessory battery 18 via a DCDC converter 20, and the accessory battery 18 can be charged by supplying electric power from the high-voltage battery 14 to the accessory battery 18. Note that the accessory battery 18 corresponds to the "auxiliary power source" in the embodiment of the present invention.

[0019] A controller 21 for controlling the engine 1, the motor 2, the transmission 9, the alternator 12, etc. described above is provided. This controller 21 is mainly composed of a microcomputer, similar to the controller provided in a conventional vehicle, and signals are input from various sensors provided in the vehicle Ve. Based on the input signals and arithmetic expressions, maps, etc. stored in advance, signals for controlling the engine 1, the motor 2, the transmission 9, the alternator 12, etc. are output.

[0020] The vehicle Ve configured as described above determines the power required for the engine 1 based on the drive power required for the vehicle Ve and the charging power required for each battery 14, 18, and controls the intake air amount and the fuel injection amount. Based on the required charging power of the high-voltage battery 14, the power generation power of the motor 2 is controlled, and based on the required charging power of the accessory battery 18, the power generation power of the alternator 12 is controlled. Note that the required power of the engine 1 is set in consideration of mechanical losses by the torque converter 4 and the transmission 9 and electrical losses when power is converted into electric power by the motor 2 and the alternator 12.

[0021] As described above, the greater the driving torque output by the engine 1 and the higher the rotational speed, the greater the abnormal noise and vibration. That is, the greater the output (power) of the engine 1, the greater the abnormal noise and vibration. Therefore, as shown by the solid line in FIG. 2, an upper limit value of the output of the engine 1 is determined to suppress the abnormal noise and vibration from becoming excessive. Further, since the engine 1 outputs torque according to the intake air amount, as shown by the broken line in FIG. 2, the higher the altitude and the thinner the air, the lower the maximum value of the output of the engine 1. That is, as shown in FIG. 2, when the altitude is e1 or lower, the engine 1 is operated in a region below the upper limit value of the output determined based on the abnormal noise and vibration, and when the altitude is higher than e1, the engine is operated in a region below the maximum value of the output corresponding to that altitude. That is, the upper limit value of the output of the engine 1 is determined based on suppressing the abnormal noise and vibration and the maximum value corresponding to the altitude.

[0022] In the control device according to the embodiment of the present invention, when the required power of the engine 1 determined as described above exceeds the upper limit value (upper limit power) of the output of the engine 1, the generated power of the motor 2 and the alternator 12 is appropriately controlled. A flowchart for explaining an example of the control is shown in FIG. 3.

[0023] In the control example shown in FIG. 3, first, it is determined whether or not the alternator 12 is operating (step S1). That is, it is determined whether or not the engine 1 is driving and the field current is being supplied to the alternator 12.

[0024] If it is determined negatively in step S1 because the alternator 12 is not operating, this routine is terminated once. On the contrary, if it is determined affirmatively in step S1 because the alternator 12 is operating, it is determined whether the required power of the engine 1 exceeds the upper limit value (step S2). Specifically, in the same manner as the control device of a conventional vehicle, the power (required drive power) required to drive the vehicle Ve based on the accelerator opening and the vehicle speed is calculated, the required power generation power of the motor 2 is calculated based on the remaining charge amount (SOC) of the high-voltage battery 14, and the required power generation power of the alternator 12 is calculated based on the remaining charge amount (SOC) of the auxiliary battery 18. Then, these powers and the power generation power are added to obtain the required power of the engine 1. Also, the altitude of the position where the vehicle Ve is traveling is obtained based on a navigation system or the like, and the upper limit value of the output of the engine 1 is calculated. Then, the required power of the engine 1 is compared with the upper limit value of the output of the engine 1.

[0025] If it is determined negatively in step S2 because the required power of the engine 1 does not exceed the upper limit value, this routine is terminated once as it is. That is, the engine 1, the motor 2, or the alternator 12 is controlled based on the required power and the required power generation power. On the contrary, if it is determined affirmatively in step S2 because the required power of the engine 1 exceeds the upper limit value, the required power generation power required for the motor 2 is decreased (step S3). Specifically, the power obtained by subtracting the required drive power and the required power generation power of the alternator 12 from the upper limit value of the output of the engine 1 is set as the required power generation power of the motor 2. That is, power generation is prioritized by the alternator 12 over the motor 2.

[0026] Next, it is determined whether the SOC of the high-voltage battery 14 is less than or equal to a predetermined value (allowable lower limit value) (step S4). This step S4 is a step for suppressing the excessive decrease in the SOC of the high-voltage battery 14, and the SOC can be detected and determined by detecting the output voltage of the high-voltage battery 14 or the like. Note that the predetermined value in step S4 corresponds to the "first predetermined remaining amount" in the embodiment of the present invention.

[0027] When it is negatively determined in step S4 because the SOC of the high-voltage battery 14 is higher than a predetermined value, this routine is once terminated as it is. That is, the output of the engine 1 is set to the upper limit value, the alternator 12 is controlled according to the required power generation, and the motor 2 is controlled according to the required power generation determined in step S3. On the contrary, when it is positively determined in step S4 because the SOC of the high-voltage battery 14 is equal to or less than the predetermined value, the required power generation of the alternator 12 is decreased within the range where the SOC of the auxiliary battery 18 becomes equal to or more than the predetermined value (step S5), and this routine is once terminated. Specifically, the required driving power and the power generation power of the alternator 12 within the range where the SOC of the auxiliary battery 18 becomes equal to or more than the predetermined value are subtracted from the upper limit value of the output of the engine 1, and set as the required power generation of the motor 2. That is, the power generation power of the alternator 12 is set to the minimum necessary, and the power generation power of the motor 2 is increased. That is, the power generation by the motor 2 is prioritized over the power generation by the alternator 12. Note that the predetermined value for maintaining the SOC in this auxiliary battery 18 corresponds to the "second predetermined remaining amount" in the embodiment of the present invention.

[0028] FIG. 4 schematically shows the relationship between the required drive power Pd, the generated power Palt of the alternator 12, and the generated power Pm of the motor 2 when step S5 is executed. The upper limit value (or maximum value) of the output of the engine 1 is indicated by a dashed-dotted line. As shown in FIG. 4, the power required for the engine 1 obtained by adding the required generated power Pcharge (Pm + Palt) of the motor 2 and the alternator 12 to the required drive power Pd exceeds the upper limit value of the output of the engine 1. Further, in the example shown in FIG. 4, the case where the SOC of the high-voltage battery 14 is higher than a predetermined value is shown. Therefore, when the above step S5 is executed, the generated power Palt of the alternator 12 is reduced to the minimum value in the range where the SOC of the accessory battery 18 becomes a predetermined value or more. The generated power is denoted as Palt1. Therefore, the generated power of the motor 2 is set to the magnitude obtained by subtracting the required drive power Pd and the reduced generated power Palt1 of the alternator 12 from the upper limit value of the output of the engine 1. The generated power is denoted as Pm1.

[0029] As described above, when the power required for the engine 1 is equal to or higher than the upper limit value, by limiting the generated power of the motor 2, the generated power of the alternator 12 can be ensured, and the accessory battery 18 can be appropriately charged. Further, when the power required for the engine 1 is equal to or higher than the upper limit value and the SOC of the high-voltage battery 14 is less than a predetermined value, the generated power of the alternator 12 is limited to the power in the range where the SOC of the accessory battery 18 becomes a predetermined value or more, and the generated power of the motor 2 is determined. Therefore, while suppressing an excessive decrease in the SOC of the accessory battery 18, the high-voltage battery 14 can be preferentially charged. That is, the power of the engine 1 can be appropriately distributed to the required drive power Pd, the charging of the high-voltage battery 14, and the charging of the accessory battery 18, and while suppressing an excessive decrease in the charging power of each battery 14, 18, a decrease in the driving force can be suppressed.

Explanation of Signs

[0030] 1 Engine 2 Motor 12 Alternator 14 High-voltage battery 17 High-voltage electrical equipment 18 Auxiliary battery 19 Low-voltage electrical equipment 21 Controller Ve Hybrid vehicle

Claims

[Claim 1] A control device for a hybrid vehicle including a motor configured to be able to convert engine power into electric power and to charge a main power supply with the generated electric power, and an alternator that converts engine power into electric power and charges an auxiliary power supply with the generated electric power, limiting the generated power of the motor when a required power of the engine based on a required driving force of the hybrid vehicle, a required generated power of the motor, and a required generated power of the alternator is equal to or greater than a predetermined upper limit power; When the required power of the engine is equal to or greater than the upper limit power and the remaining charge of the main power supply is equal to or less than a predetermined first predetermined remaining amount, the power generated by the alternator is limited to power that will cause the remaining charge of the auxiliary power supply to be equal to or greater than a predetermined second predetermined remaining amount, thereby increasing the power generated by the motor. A control device for a hybrid vehicle.

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