JP7418912B2 - Hybrid system control device - Google Patents

Description

The present invention relates to a control device for a hybrid system installed in a vehicle.

2. Description of the Related Art Conventionally, hybrid systems are known that include an engine and a drive motor that is a drive source for driving. For example, in a series hybrid system, engine power is converted to electric power by a generator motor, a drive motor is driven by the electric power and the output of a battery, and the power of the drive motor is transmitted to drive wheels.

Engines have a relationship between engine speed and engine torque at which the best thermal efficiency is achieved. According to this relationship, the engine torque and engine speed are set according to the generated power required of the generator motor, and the engine is driven so as to obtain the set engine torque and engine speed. It can be operated with a thermal efficiency of

JP2006-347283A JP 2015-128933 Publication

However, the power generated by the engine is converted into DC power by a generator motor and an inverter, and is used to charge a battery or drive a drive motor. Therefore, the system efficiency of the hybrid system is determined by the thermal efficiency of the engine, the efficiency of the generator motor, and the efficiency of the inverter. Therefore, even if the engine is operating at the best thermal efficiency, the system efficiency is not necessarily good.

An object of the present invention is to provide a control device for a hybrid system that can improve system efficiency.

In order to achieve the above object, a control device for a hybrid system according to the present invention includes an engine, a generator motor that generates electricity using the power of the engine, a battery, a boost converter that boosts the output voltage of the battery to the system voltage, and a system voltage that is driven by the system voltage. A control device for a hybrid system, which is equipped with a drive motor mounted on a vehicle and transmits the power of the drive motor to the drive wheels of the vehicle, is created for each of a plurality of mutually different system voltages, and is created for each of a plurality of mutually different system voltages, and is configured to control the target engine rotation speed of the engine. and a storage means for storing a target operating line indicating the relationship between the target operating line and the target engine torque; , and engine control means for controlling the driving of the engine.

According to this configuration, the storage means stores a target operating line indicating the relationship between engine rotation speed and engine torque. The target operating line is created for each of a plurality of different system voltages. Then, a target operating line corresponding to the system voltage is selected, a target engine speed and a target engine torque are set according to the selected target operating line, and the engine is adjusted so that the target engine speed and target engine torque are obtained. The drive is controlled.

System efficiency, which is determined by the thermal efficiency of the engine and the power generation efficiency of the generator motor and inverter, changes depending on the system voltage. Since it is possible to actually measure the system efficiency for each system voltage, it is necessary to actually measure the system efficiency for each system voltage in advance, and based on the actual measurement data, create a target operating line for the engine that will result in high system efficiency for each system voltage. I can do it. Therefore, if the created target operating line for each system voltage is stored in the storage means, the system efficiency can be improved by controlling the engine drive according to the target operating line corresponding to the system voltage. As a result, it is possible to reduce energy loss in the hybrid system, and it is possible to improve the power performance and fuel efficiency of a vehicle equipped with the hybrid system.

If a region that reduces the system efficiency of the hybrid system exists on the target operating line according to the system voltage, the engine control means controls at least one of the target engine speed and the target engine torque so that the engine does not operate in the region. It is preferable to set

Even if the target operating line for the engine is created so that the system efficiency is high, the system efficiency may decrease in some areas on the target operating line. By setting at least one of the target engine speed and target engine torque so that the engine does not operate in this region, it is possible to suppress local decreases in system efficiency and further improve the vehicle's power performance and fuel efficiency. be able to.

According to the present invention, system efficiency can be improved.

1 is a block diagram showing the configuration of a vehicle equipped with a hybrid system according to an embodiment of the present invention. FIG. 3 is a diagram showing a target operating line of the engine, and shows a target operating line corresponding to system voltage A (V). It is a diagram showing a target operating line of the engine, and shows a target operating line corresponding to system voltage B (V). FIG. 3 is a diagram showing a target operating line of the engine, and shows a target operating line corresponding to system voltage C(V).

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Hybrid vehicle>
FIG. 1 is a block diagram showing the configuration of a vehicle 1 equipped with a hybrid system 2 according to an embodiment of the present invention.

The vehicle 1 is equipped with a series type hybrid system 2. The hybrid system 2 includes an engine (ENG) 11, a generator motor (MG1) 12, a drive motor (MG2) 13, a drive battery 14, and a PCU (Power Control Unit) 15.

Engine 11 is, for example, a gasoline engine or a diesel engine. An engine output gear 22 is provided on the crankshaft 21 of the engine 11 so as to rotate together with the crankshaft 21.

The generator motor 12 is, for example, a permanent magnet synchronous motor. A generator motor gear 24 is provided on the rotating shaft 23 of the generator motor 12 so as to rotate together with the generator motor gear 24 . The generator motor gear 24 meshes with the engine output gear 22. The generator motor 12 is used as a starter motor for cranking the engine 11 when the engine 11 is stopped. After the engine 11 is started, the generator motor 12 functions as a generator that converts the power of the engine 11 into electric power.

The drive motor 13 is, for example, a permanent magnet synchronous motor larger than the generator motor 12. A motor output gear 26 is provided on the rotating shaft 25 of the drive motor 13 so as to rotate together with the rotating shaft 25 .

Motor output gear 26 is coupled to power transmission mechanism 3 mounted on vehicle 1. The power transmission mechanism 3 includes a counter shaft 31, a counter gear 32, an output gear 33, and a differential gear 34. The counter shaft 31 is provided parallel to the rotation shaft 25 of the drive motor 13. The counter gear 32 and the output gear 33 are provided on the counter shaft 31 so as to rotate together. The output gear 33 meshes with a ring gear 35 of a differential gear 34. Motor output gear 26 meshes with counter gear 32.

The power of drive motor 13 is transmitted to differential gear 34 via motor output gear 26, counter gear 32, and output gear 33. The power transmitted to the differential gear 34 is then transmitted to the left and right drive wheels 5 of the vehicle 1 via the left and right drive shafts 4 . As a result, the left and right drive wheels 5 rotate, and the vehicle 1 travels forward or backward.

The driving battery 14 is a battery pack that is a combination of a plurality of secondary batteries (for example, lithium ion batteries). The driving battery 14 outputs, for example, DC power of about 200 to 350 V (volts).

The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13, and includes a first inverter (MG1 INV) 41, a second inverter (MG2 INV) 42, and a boost converter (BstCONV) 43.

When the vehicle 1 is accelerating, the drive motor 13 is operated in power running, and the drive motor 13 generates power for power running. At this time, the DC power output from the drive battery 14 is boosted as necessary by the boost converter 43, the DC power output from the boost converter 43 is converted into AC power by the second inverter 42, and the AC power is is supplied to the drive motor 13. As a result, the power of the drive battery 14 is consumed.

Further, when the engine 11 is started, the DC power output from the drive battery 14 is boosted by the boost converter 43, the boosted DC power is converted to AC power by the first inverter 41, and the AC power is transferred to the generator motor 12. is supplied to As a result, the generator motor 12 is motored, and the engine 11 is motored by the generator motor 12. This motoring causes the crankshaft of the engine 11 to rotate, and when its rotational speed increases to the rotational speed necessary for starting, the ignition plug of the engine 11 is sparked and the engine 11 is started.

When the generator motor 12 is operated to generate electricity while the engine 11 is operating, the generator motor 12 generates alternating current power. The AC power generated by the generator motor 12 is converted into DC power by the first inverter 41 . Then, the DC power output from the first inverter 41 is converted into AC power by the second inverter 42, and the AC power is supplied to the drive motor 13. Furthermore, when it is not necessary to supply power to the drive motor 13, the DC power output from the first inverter 41 is stepped down by the step-up converter 43, and the stepped down DC power is supplied to the drive battery 14. , the driving battery 14 is charged.

When the vehicle 1 is decelerating, the drive motor 13 is operated regeneratively, and the power transmitted from the drive wheels 5 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 acts as a resistance in the traveling drive system, and the resistance acts as a braking force (regenerative braking force) that brakes the vehicle 1. The AC power generated by the drive motor 13 is converted into DC power by the second inverter 42 . Then, the DC power output from the second inverter 42 is stepped down by the step-up converter 43, and the stepped-down DC power is supplied to the drive battery 14, thereby charging the drive battery 14.

Also. The vehicle 1 is equipped with an ECU (Electronic Control Unit) 6 that includes a microcomputer (microcontroller unit) 51 . The microcomputer 51 includes, for example, a CPU, a nonvolatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). Although only one ECU 6 is shown in FIG. 1, the vehicle 1 is equipped with a plurality of ECUs having the same configuration as the ECU 6 in order to control each part. A plurality of ECUs including the ECU 6 are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol.

<Engine control>
2, 3, and 4 are diagrams showing target operating lines of the engine 11.

A nonvolatile memory built into the microcomputer 51 of the ECU 6 stores a target operating line for the engine 11 in the form of a map. The target operating line is a characteristic line that shows the relationship between the target engine speed and target engine torque of the engine 11. Target operating lines are created for each of multiple system voltages. The system voltage is a DC voltage supplied to the second inverter 42 of the PCU 15. 2, 3, and 4 are target operating lines corresponding to mutually different system voltages A (V), system voltages B (V), and system voltages C (V).

The target operating line is created based on the actual measured value of the system efficiency of the hybrid system 2. The system efficiency of the hybrid system 2 is determined by the thermal efficiency of the engine 11, the efficiency of the generator motor 12, the efficiency of the first inverter 41, and the efficiency of the second inverter 42. System efficiency maps are shown in FIGS. 2, 3 and 4 along with target operating lines. The system efficiency map shows contour lines plotting the position of engine speed and engine torque at equal system efficiency.

By actually measuring the system efficiency by changing the rotation speed and torque of the engine 11 while setting the system voltage to A (V), the system efficiency map shown in FIG. 2 can be created based on the measured data. . A target operating line can then be created from the system efficiency map. The target operating line corresponding to system voltage B(V) and the target operating line corresponding to system voltage C(V) are also created using the same method as the target operating line corresponding to system voltage B(V).

In order to control the drive of the engine 11, the ECU 6 uses the microcomputer 51 to adjust the accelerator opening degree, which is the ratio of the operation amount by the driver to the maximum operation amount of the accelerator pedal provided in the cabin of the vehicle 1, and the vehicle speed of the vehicle 1. A corresponding target motor torque of the drive motor 13 is set, and a system voltage required to output the target motor torque is determined. Then, by controlling the boost converter 43, the output voltage of the drive battery 14 is boosted to the system voltage. Further, the microcomputer 51 of the ECU 6 selects a target operating line according to the system voltage, and sets the target engine speed and target engine torque in accordance with the selected target operating line. If the system efficiency decreases in some region on the target operating line, at least one of the target engine speed and the target engine torque is adjusted so that the engine 11 does not operate in the region, as shown by the broken line in FIG. is set at a point that is off the target motion line. Then, the drive of the engine 11 is controlled by the microcomputer 51 of the ECU 6 so that the target engine speed and target engine torque are obtained.

Note that the accelerator opening degree and vehicle speed may be input from another ECU to the ECU 6 via CAN communication, or a detection signal may be output according to the operation amount of the accelerator pedal operated by the user (driver) of the vehicle 1. An accelerator sensor and a vehicle speed sensor that outputs a detection signal according to the vehicle speed of the vehicle 1 may be connected to the ECU 6, and the ECU 6 may calculate the detection signal from these detection signals.

<Effect>
As described above, the nonvolatile memory built into the microcomputer 51 of the ECU 6 stores a target operating line indicating the relationship between the engine rotation speed and the engine torque. The target operating line is created for each of a plurality of system voltages that are different from each other. Then, a target operating line corresponding to the system voltage is selected, a target engine speed and a target engine torque are set according to the selected target operating line, and the engine 11 is set so that the target engine speed and target engine torque are obtained. drive is controlled. Since the target operating line is a characteristic line that shows the relationship between the engine rotation speed and engine torque at which the system efficiency becomes high for each system voltage, the drive of the engine 11 is controlled according to the target operating line according to the system voltage. This improves system efficiency. As a result, it is possible to reduce energy loss in the hybrid system 2, and it is possible to improve the power performance and fuel efficiency of the vehicle 1 in which the hybrid system 2 is mounted.

In the ECU 6, when a region that reduces the system efficiency of the hybrid system 2 exists on the target operating line according to the system voltage, at least one of the target engine speed and the target engine torque is adjusted so that the engine 11 does not operate on the region. Set. Thereby, local reduction in system efficiency can be suppressed, and the power performance and fuel efficiency of the vehicle 1 can be further improved.

<Modified example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, in the above-described embodiment, the configuration of the series type hybrid system 2 was taken as an example, but the present invention is applicable to a type of hybrid system other than the series type, such as a series/parallel type. In a series/parallel type hybrid system, for example, the engine and motor are connected to a planetary gear mechanism, and the power from the engine can be divided and distributed to the motor and drive wheels. Power can be combined and transmitted to the drive wheels.

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Vehicle 2: Hybrid system 5: Drive wheel 6: ECU (control unit)
11: Engine 12: Generator motor 13: Drive motor 14: Drive battery (battery)
43: Boost converter 51: Microcomputer (memory means, engine control means)

Claims (1)

an engine, a generator motor that generates electricity using the power of the engine, a battery, a step-up converter that boosts the output voltage of the battery to a system voltage , a drive motor that is driven by the system voltage , and a generator motor that converts DC power into AC power. a first inverter that converts the AC power generated by the generator motor into DC power; and a first inverter that converts the DC power into AC power and supplies it to the drive motor, and converts the AC power generated by the drive motor into DC power. A control device for a hybrid system that is mounted on a vehicle that is equipped with a second inverter that converts into electric power, and that transmits the power of the drive motor to the drive wheels of the vehicle,
storage means for storing a target operating line created for each of the plurality of system voltages that are different from each other and indicating a relationship between a target engine speed and a target engine torque of the engine;
an engine control unit that selects the target operating line according to the system voltage, sets the target engine rotation speed and the target engine torque in accordance with the selected target operating line, and controls driving of the engine. fruit ,
The engine control means is configured to set the system efficiency of the hybrid system on the target operating line according to the system voltage, including the thermal efficiency of the engine, the efficiency of the generator motor, the efficiency of the first inverter, and the efficiency of the second inverter. If there is a region in which the system efficiency, which is determined by the efficiency of Control device.

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