WO2008153161A1 - Hybrid electric vehicle - Google Patents

Abstract

A hybrid electric vehicle (10) includes an engine (22) and motors (MG1, MG2) as drive sources. A hybrid ECU (70) outputs a control signal to an engine ECU (24) and a motor ECU (40) so that an engine (22) performs an intermittent operation by alternately repeating an operation period and halt period and a motor (MG1 or MG2) generates electricity by the engine (22) in the operation period. When the vehicle velocity is smaller than a predetermined threshold value, the motor ECU (40) sets a carrier frequency of an inverter (41 or 42) in the halt period lower than a carrier frequency of the inverter (41 or 42) in the operation period.

Description

High electric vehicle technology

 The present invention relates to a hybrid electric vehicle including an engine and a motor as drive sources. BACKGROUND ART A hybrid electric vehicle includes a driving motor (electric motor) as a driving source in addition to an engine field (internal combustion engine). The drive motor is an AC motor driven by an AC current, and a power converter such as a chamber is required to drive the AC motor with a DC current. In the drive motor, inverters and other power converters perform power conversion for high power by switching at high frequencies, which may heat the power transistor. Therefore, it is necessary to take measures to suppress the heat generated in the power transistor when controlling the driving mode.

 As one of the measures to prevent heating, a technology that suppresses heat generated in the evening by reducing the carrier frequency of the P WM (pulse width modulation) signal, that is, the switching frequency of the transistor, is known. . The carrier frequency can be reduced, for example, when the motor speed is low enough, when starting on a hill, when the accelerator is stepped on with the side brake on, or when the wheel is hitting the car stop. This is done when it can be considered locked by an external force. In addition, a technique is known in which the temperature of the power transistor is detected and the carrier frequency is changed according to the temperature change to suppress the heat generated in the chamber.

JP-A-5-3 0 8 7 0 4 describes a propulsion operation to save a train stuck on a track due to a failure by another train, and disconnects the failed unit and operates only with the remaining unit. Unit cut operation, low speed constant speed operation during car wash A technology is disclosed in which the switching frequency is set low when switching from the normal operation mode to the special operation mode such as the above, thereby suppressing the loss of the switching element.

 In Japanese Patent Laid-Open No. 2 0 3-3 2 4 9 6 7, in an inverter unit equipped with a control board in a casing, temperature control means is provided on the control board to detect the ambient temperature in the casing. Thus, a technique for grasping the operation status of the inverse device is disclosed.

 By the way, the inverter installed in a hybrid electric vehicle has a limited installation space, so it often has to be placed near the engine. Inverse evening is often cooled by cooling water to suppress the heating of internal control boards. However, if the engine is left idling or running at a low speed after running on a high load such as on a slope, the cooling water temperature rises due to the high load running, and the cooling efficiency of the imper May decrease. In addition, when driving at low speed, the cooling wind taken into the engine room decreases, and the cooling effect of the chamber overnight decreases. Disclosure of the invention

 An object of the present invention is to suppress heat generation in an inverter even when a hybrid electric vehicle travels at a high load and the engine is left in an idling state or continues to travel at a low speed.

 The hybrid electric vehicle according to the present invention is a hybrid electric vehicle including an engine and a motor as a drive source, wherein the engine performs an intermittent operation in which an operation period and a rest period are alternately repeated, and the operation period A control unit that causes the motor to generate electric power using the power of the engine, and a motor control unit that supplies a pulse modulation signal having a predetermined carrier frequency to a chamber connected to the motor; When the engine is intermittently operated and the vehicle speed is lower than a predetermined threshold speed, a motor control unit is provided that sets the carrier frequency of the inverter during the pause period lower than the carrier frequency of the inverter during the operation period. .

In one aspect of the hybrid electric vehicle according to the present invention, the motor controller When the engine is intermittently operated and the vehicle speed is zero, the supply of the pulse modulation signal to the inverter during the pause period is stopped.

 In one aspect of the hybrid electric vehicle according to the present invention, the motor control unit is configured to perform the inverter control only when the engine load immediately before the engine performs intermittent operation is greater than a predetermined threshold value. Set lower than the frequency, or stop supplying the pulse modulation signal to the chamber.

 According to the present invention, when the vehicle speed is lower than the predetermined threshold speed, the carrier frequency during the engine idle period is set lower than the carrier frequency during the engine operation period. Heat generation can be suppressed. Further, according to the present invention, for example, even when a hybrid electric vehicle travels at a high load and the engine is left in an idling state or continues to travel at a low speed, the heat generation of the chamber overnight is suppressed. be able to. Brief Description of Drawings

 FIG. 1 is a diagram showing functional blocks of a hybrid electric vehicle according to the present embodiment.

 FIG. 2 is a diagram showing an example of a timing chart related to the carrier frequency corresponding to the operating state of the engine in the idling state.

 FIG. 3 is a diagram showing an example of a timing chart relating to the switching signal corresponding to the engine operating state in the idling state. Explanation of symbols

1 0 Hybrid electric vehicle, 2 2 Engine, 2 4 Engine ECU, 2 6 Crankshaft, 3 0 Power distribution mechanism, 3 2 Drive shaft, 3 4 Reducer, 3 6 Drive shaft, 4 0 Motor ECU, 4 1 , 4 2 Inverter, 50 notch, 5 2 battery ECU, 70 hybrid ECU, 80 0 dani switch. BEST MODE FOR CARRYING OUT THE INVENTION

 DESCRIPTION OF EXEMPLARY EMBODIMENTS Embodiments specifically showing the best mode for carrying out the invention will be described below with reference to the drawings.

 FIG. 1 is a diagram showing a schematic configuration of a hybrid electric vehicle 10 according to the present embodiment. As shown in the figure, the hybrid electric vehicle 10 includes an engine 22, a three-shaft power distribution mechanism 30 connected via a damper to a crankshaft 26 as an output shaft of the engine 22, and a power distribution Motorized MG 1 connected to mechanism 30 and motorized MG 2 connected to power distribution mechanism 30 via drive shaft 32, and hybrid electronic control for controlling the entire power output device Unit (hereinafter referred to as hybrid ECU) 70. The drive shaft 3 2 transmits the power from the engine 2 2 and the motors MG 1 and MG 2 to the drive wheels via the speed reducer 3 4 and the drive shaft 卜 3 6.

 The engine 22 is an internal combustion engine that outputs power by receiving a hydrocarbon-based fuel such as gasoline or light oil from a fuel tank (not shown). The engine 22 has an engine electronic control unit (hereinafter referred to as engine ECU) 2 4 that receives signals from various sensors that detect the operating state of the engine 22 and fuel injection control, ignition control, and intake air amount adjustment control. Are under operation control. The engine E C U 24 communicates with the hybrid E C U 70 and controls the operation of the engine 22 by a control signal from the hybrid E C U 70. Further, the engine E C U 24 outputs data relating to the operating state such as the engine speed of the engine 22 to the hybrid E C U 70 as necessary.

 The power distribution mechanism 30 is suitable for the vehicle driving force for directly driving the drive wheels by the power of the engine 22 and the power generation driving force for operating the motor MG 1 by the power of the engine 22 to generate power. A known so-called planetary gear mechanism for dividing is provided. The power distribution mechanism 30 further includes a mechanism capable of transmitting rotation via the rotor shaft of the motor MG 2 and the drive shaft 32.

The motor MG 1 and the motor MG 2 are both configured as well-known synchronous generator motors that can be driven by a three-phase alternating current as a generator and that can be driven as an electric motor. Power the battery 50 Take a trap. The motors MG 1 and MG 2 are driven and controlled by a motor electronic control unit (hereinafter referred to as motor ECU) 40 via inverters 41 and 42. The motor ECU 40 has signals necessary for controlling the motor MG 1 and MG 2, such as signals from the rotational position detection sensor that detects the rotational position of the rotor of the motor MG 1 and MG 2, and current sensors. The current applied to MG1 and MG2 detected by is input. The motor ECU 40 outputs a switching signal (pulse width modulation signal) to inverters 41 and 42. The motor ECU 40 inputs the motor MG 1 and motor MG 2 rotation speeds from the motor MG 1 and motor MG 2 rotation speeds, and the current sensor inputs the motor speed MG 1 and motor MG 2 rotation speeds 41 and 42. Inverter current I 1, I 2, Motor MG 1 and torque command value that is the torque value to be output from motor MG 2 are input from the hybrid ECU 70, and the carrier frequency is calculated. A switching signal is output to

The battery 50 is managed by a battery electronic control unit (hereinafter referred to as a battery ECU) 52. The battery ECU 52 has signals necessary to manage the battery 50, such as the voltage across the terminals from the voltage sensor installed between the terminals of the battery 50, and the power line connected to the output terminal of the battery 50. The charging / discharging current from the attached current sensor, the battery temperature from the temperature sensor attached to the battery 50, etc. are input. Further, the battery ECU 52 calculates data relating to the state of the battery 50 based on each input signal as necessary, and outputs the data to the hybrid ECU 70 by communication. The battery ECU 52 also calculates the state of charge (SOC) based on the integrated charge / discharge current detected by the current sensor to manage the battery 50. The hybrid ECU CU70 has an 80 The engine signal from the engine ECU 24 and the engine speed R ev of the engine 22 are input via the input port. The hybrid ECU 70 further includes a shift position SP from the shift position sensor that detects the operation position of the shift lever, and an accelerator pedal position that detects the amount of depression of the accelerator pedal. The accelerator opening A cc from the engine sensor, the brake pedal depression amount detected, the brake pedal position BP from the brake pedal position sensor, and the vehicle speed V from the vehicle speed sensor are input via the input port. As described above, the hybrid ECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via a communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, and the battery ECU 52. Is doing.

 In the present embodiment, when the hybrid electric vehicle 10 configured as described above is left in an idling state, the hybrid ECU 70 operates the engine 22 intermittently, and the motor MG is driven by the power of the engine 22. Drive 1 to charge battery 50 intermittently. That is, the hybrid ECU 70 outputs a control signal to the engine ECU 24 and the motor ECU 40 so that the engine 22 performs intermittent operation in which the operation period and the rest period are alternately repeated. By charging the battery 50 during idling in this way, it is possible to prevent the motor MG 1 from being driven due to insufficient charging of the battery 50 at the next start. However, when a hybrid electric vehicle is left in an idling state after running at a high load such as on a slope, the temperature of the cooling water for cooling the inverters 41 and 42 also increases due to the high load running. As a result, the cooling efficiency of Inver evening 41 and 42 may decrease. In addition, when the hybrid electric vehicle runs at a low speed, the cooling wind taken into the engine room decreases, and the cooling effect of the inverter 41, 2 is reduced.

Inverters 41 and 42, on the other hand, the higher the carrier frequency of the switching signal, the more stable the drive and the suppression of abnormal noise. However, the higher the carrier frequency, the more easily the power transistors provided in Inver evening 41 and 42 are heated. In other words, the lower the carrier frequency, the more the power transistor heating can be suppressed. For this reason, when the hybrid electric vehicle 10 is left in an idling state, it is conceivable to always set the carrier frequency low to suppress heating of the power transistor. However, as described above, during idling, the motor MG 1 is driven and the battery 50 is charged. Is done. In other words, if the carrier frequency is always set to a low value when left in an idling state, there is a risk that abnormal noise may be generated from the motor MG 1 or the motor MG 2 that is driven when the battery 50 is charged. is there.

 Therefore, in the present embodiment, when the hybrid electric vehicle 10 is left in an idling state, the period during which the engine 22 is at rest, that is, while the torque of the motor MG 1 and the engine MG 2 is zero, The heat generated by the inverters 41 and 42 is suppressed by setting the carrier frequency that the motor ECU 40 outputs to the chambers 41 and 42 low.

FIG. 2 shows a timing chart regarding the carrier frequency corresponding to the operating state of the engine 22 in the idling state. As shown in Fig. 2, the motor EC U40 determines that the motor MG 1 and the motor MG 2 are not operating during the idling state in which the engine 22 is intermittently operated while the engine 22 is idle. Thus, the carrier frequency is set lower than the period during which the engine 22 is operating. More specifically, when the carrier frequency during the operation period of the engine 22 is set to 20 kHz, for example, the motor ECU 40 sets the carrier frequency during the idle period of the engine 22 to 10 kHz or 1 kHz, for example. In Fig. 2, (a) shows the temperature of the electronic components on the control board inside the inverter 41 or 42 when the carrier frequency is set to 20 kHz during both the operation and rest periods of the engine 22. (Parts driven at carrier frequency). (B) shows the electronic component temperature when the carrier frequency during the operation period of the engine 22 is 20 kHz and the carrier frequency during the idle period of the engine 22 is 10 kHz. (c) shows the electronic component temperature when the carrier frequency during the engine 22 operation period is 20 kHz and the carrier frequency during the engine 22 idle period is 1 kHz. That is, as shown in FIG. 2, it can be seen that the lower the carrier frequency during the idle period of the engine 22, the more the temperature of the electronic components inside the inverter can be suppressed. In the above embodiment, an example in which the carrier frequency is lowered during the idle period of the engine 22 has been described. However, for example, as shown in FIG. 3, the motor ECU 40 may turn off the switching signal, that is, prevent the switching signal from being output to the inverters 41 and 42 during the idle period of the engine 22. This As a result, as shown in FIG. 3 (d), it is possible to suppress an increase in the temperature of the electronic components inside the inverter as compared with the case where the switching signal is turned on during the engine 22 suspension period.

 As described above, the engine frequency of the switching signal input to the inverter overnight is lowered or the switching signal is not input to the inverter overnight during the idle period of the engine 22 during idling, where the temperature rise tends to occur. With this configuration, it is possible to suppress an increase in the temperature of the electronic component during the idling.

 Inver evening mounted on hybrid electric vehicles is often placed in a high-temperature environment such as near the engine room due to space constraints. Therefore, there is a high possibility that the circuit provided by Inver evening will be at a high temperature, and it is necessary to consider the heat resistance performance of the circuit. To improve the heat resistance performance, the circuit may be enlarged. However, according to the present embodiment, since the carrier frequency is set low or the switching signal is turned off during the idle period of the engine 22 during idling, an increase in the temperature of electronic components inside the inverter can be suppressed. Therefore, there is no problem even if the heat resistance of the circuit provided by Inveru is lowered to some extent. Therefore, an increase in the size of the circuit for improving the heat resistance can be suppressed. Also, by setting the carrier frequency low during the idle period of the engine 22 in which the motor is not driven, or by turning off the switching signal, it is possible to suppress abnormal noise that occurs when the motor rotates.

In the above embodiment, when the hybrid electric vehicle is in an idling state, that is, when the engine 22 is intermittently operated while the vehicle is stopped, the value of the carrier frequency is changed or the switching signal is turned off. explained . However, for example, the carrier frequency value may be changed or the switching signal may be turned off in accordance with the vehicle speed during the intermittent operation of the engine 22. That is, the motor ECU 40 sets the carrier frequency low when the vehicle speed is lower than the predetermined threshold speed during the pause period when the engine 22 is intermittently operated, and further, when the vehicle speed becomes zero, that is, When the hybrid electric vehicle stops, the switching signal may be turned off. Furthermore, in the above embodiment, an example is described in which the carrier frequency is set low or the switching signal is turned off during the pause period when the engine 22 is intermittently operated, regardless of the traveling state immediately before shifting to the idling state. did. However, it is preferable to suppress the heat generation of electronic components in Invert evening when the engine is left idling or running at low speed after running on a high load such as running on a slope. Therefore, the carrier frequency is set low during the idle period of engine 22 only when engine 22 is shifted to intermittent operation (idling state) immediately after the hybrid electric vehicle travels at a high load. May turn off the switching signal. In this case, for example, in the motor ECU 40, the load (torque and inverter current) of the motor MG1 and MG2 immediately before the engine 22 shifts to the intermittent operation (idling state) is below a predetermined threshold. It is determined whether or not it is large, and only when it is large, the carrier frequency may be set low or the switching signal may be turned off during the idle period when the engine 22 is intermittently operated.

Claims

1. A hybrid electric vehicle equipped with an engine and a motor drive as a driving source,  A control unit that controls the engine to perform intermittent operation that alternately repeats an operation period and a rest period, and generates power in the motor by the power of the engine in the operation period;  Applying a pulse with a predetermined carrier frequency to the chamber connected to the motor A motor control unit for supplying a modulation signal, wherein the engine is intermittently operated and the vehicle speed is smaller than a predetermined threshold speed; A motor control unit that sets a carrier frequency lower than the carrier frequency of the chamber during the operation period.  Eight hybrid electric car equipped with. Surrounding 2. In the eight hybrid electric vehicle according to claim 1,  The above-mentioned control unit is  When the engine is in intermittent operation and the vehicle speed is zero, the supply of the pulse modulation signal to the inverter during the pause period is stopped  Eight-prid electric car. 3. In the hybrid electric vehicle according to claim 1,  The control unit is  When the load of the motor before the engine performs intermittent operation is larger than a predetermined threshold, the carrier frequency is set lower than the inverter overnight. Eight-prid electric car. 4. In the hybrid electric vehicle according to claim 2,  The motor controller is  The hybrid electric vehicle, wherein supply of the pulse modulation signal to the inverter is stopped when the load of the motor before the engine performs intermittent operation is larger than a predetermined threshold. 5. A hybrid electric vehicle with an engine and a motor drive as a drive source,  A control unit that controls the engine to perform intermittent operation that alternately repeats an operation period and a rest period, and generates power in the motor by the power of the engine in the operation period;  A motor control unit for supplying a pulse modulation signal having a predetermined carrier frequency to a chamber connected to the motor, wherein the engine is intermittently operated and the vehicle speed is lower than a predetermined threshold speed. The chamber overnight carrier frequency during the rest period is set lower than the chamber carrier frequency during the operation period;  A motor control unit that stops the supply of the pulse modulation signal during the suspension period when the vehicle speed is zero  A hybrid electric vehicle equipped with. 6. In the hybrid electric vehicle according to claim 5,  The motor control unit is a case where the load of the motor before the engine performs intermittent operation is larger than a predetermined threshold, and the engine is intermittently operated and the vehicle speed is lower than a predetermined threshold speed. The carrier frequency of the inverter during the idle period is set lower than the carrier frequency during the operation period, and the supply of the pulse modulation signal during the idle period is stopped when the vehicle speed is zero.  A hybrid electric vehicle characterized by that.