JP5286743B2 - Output torque control device, vehicle drive system, and vehicle including vehicle drive system - Google Patents

Description

  The present invention relates to a vehicle drive system and a vehicle including the same, and more particularly to a vehicle drive system that drives wheels using a rotating electrical machine and a vehicle including the vehicle drive system.

  In recent years, vehicles using a rotating electric machine as a drive source, such as hybrid electric vehicles, fuel cell vehicles, and electric vehicles, have attracted much attention as environmentally friendly vehicles.

  In order to prevent overheating of a drive system such as an inverter that drives the rotating electrical machine, a vehicle that uses the rotating electrical machine as a drive source is usually mounted with a cooling system that cools the drive system. A typical cooling system includes a cooling water circulation path, a pump that circulates the cooling water in the circulation path, and a radiator that cools the cooling water.

  In order to prevent problems due to overheating of the drive system, a technique for limiting the output of a rotating electrical machine based on the temperature of cooling water or the temperature of elements in an inverter circuit is known.

  For example, in Patent Document 1, when the motor control unit reads the coolant temperature with a temperature sensor and the coolant temperature rises excessively, the total power of the converter and the inverter is reduced according to the temperature to suppress heat generation. Technology is disclosed.

  Further, in Patent Document 2, even if the control device generates torque with a large torque command value, if the temperature of the cooling water output from the radiator is close to the current temperature of the inverter, the cooling capacity Discloses a technique for determining that the torque command value is not high and applying a predetermined restriction to the torque command value and outputting a drive instruction or a regeneration instruction to the inverter based on the torque command value after the restriction.

  Furthermore, Patent Document 3 discloses a technique for limiting a torque command value when a failure of a blower fan that cools a current control element in an inverter circuit is detected.

  In addition, Patent Document 4 discloses a technique for limiting the torque command value when the temperature of the semiconductor element of the inverter is in a high temperature state and the time change rate of the temperature is large.

JP 2003-274509 A JP 2006-149064 A JP-A-6-98404 JP-A-10-210790

  By the way, in a cooling system such as a pump that circulates cooling water in a circulation path, there is a possibility that the flow rate of the cooling water may decrease due to pump failure, air jamming, clogging in the circulation path of the radiator or cooling water, and the like. When the flow rate of the cooling water is thus reduced, the cooling efficiency is lowered.

  However, the techniques described in the above patent documents do not take into consideration the countermeasure against the decrease in cooling efficiency when the flow rate of the cooling water is reduced due to the malfunction of the cooling system.

  An object of the present invention is to prevent a vehicle drive system including a cooling system from being overheated due to a decrease in the flow rate of cooling water.

  An output torque control device according to the present invention includes an output torque command value calculation unit that calculates an output torque command value for a rotating electrical machine drive system, and a flow rate in a fluid circulation path for cooling the rotating electrical machine drive system. An output torque limiting unit that limits the output torque command value for the rotating electrical machine drive system when the flow rate is not satisfied.

  In one aspect of the output torque control device according to the present invention, the output torque limiting unit is configured such that the flow rate of the fluid of the pump is predetermined when the rotational speed of the pump that circulates the fluid does not satisfy a predetermined specified rotational speed. It is determined that the specified flow rate is not satisfied, and the output torque command value for the rotating electrical machine drive system is limited.

  In one aspect of the output torque control device according to the present invention, the output torque limiting unit outputs the output calculated by the output torque command value calculation unit based on a coefficient determined in advance according to the rotation speed of the pump. The output torque command value for the rotating electrical machine drive system is limited by reducing the torque command value.

  A vehicle drive system according to the present invention includes a rotary electric machine drive system, a pump, a cooling device that cools the rotary electric machine drive system by circulating the fluid, and a flow rate of fluid circulated by the pump. An output torque limiting unit that limits an output torque command value for the rotating electrical machine drive system when a predetermined prescribed flow rate is not satisfied.

  In one aspect of the vehicle drive system according to the present invention, the output torque limiting unit is configured such that the flow rate of the fluid of the pump satisfies a predetermined specified flow rate when the rotation speed of the pump does not satisfy a predetermined specified rotation number. It is determined that the output torque command value for the rotating electrical machine drive system is limited.

  In one aspect of the vehicle drive system according to the present invention, the vehicle drive system includes an output torque command value calculation unit that calculates an output torque command value corresponding to a required torque for the rotating electrical machine drive system, and the output torque limit unit includes the pump The output torque command value for the rotating electrical machine drive system is limited by reducing the output torque command value corresponding to the required torque based on a coefficient determined in advance according to the number of rotations.

  A vehicle according to the present invention includes any one of the vehicle drive systems described above.

  According to the present invention, the output torque command value is limited according to the flow rate of the fluid for cooling the rotating electrical machine drive system. Therefore, it is possible to prevent the cooling efficiency from being lowered by reducing the fluid flow rate due to the malfunction of the cooling system, and the vehicle drive system from being overheated.

  The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below with reference to the drawings.

  FIG. 1 is a schematic block diagram of a vehicle drive system according to the present embodiment. In FIG. 1, a vehicle drive system 100 includes a battery B, a boost converter 10, inverters 20 and 30, motor generators MG1 and MG2, and capacitors C1 and C2 as a rotating electrical machine drive system. The system 100 includes an engine EGN as a drive source. In this embodiment, an example in which two inverters and two motor generators are provided as the rotating electrical machine drive system will be described. However, the number of inverters and motor generators is not limited to two, and may be one. Or three or more.

  The vehicle drive system 100 is mounted on, for example, a hybrid electric vehicle. Motor generator MG1 operates as a generator driven by engine EGN, and also operates as an electric motor that can start the engine. Motor generator MG2 operates as an electric motor that drives the drive wheels of the hybrid electric vehicle.

  Motor generators MG1 and MG2 are made of, for example, a three-phase AC synchronous motor. Motor generator MG1 generates an AC voltage using the rotational force from engine EGN, and outputs the generated AC voltage to inverter 20. Motor generator MG1 generates a driving force by the AC voltage received from inverter 20, and starts engine EGN. Motor generator MG2 generates a driving torque of the vehicle by the AC voltage received from inverter 30. Motor generator MG2 generates an AC voltage during regenerative braking and outputs the AC voltage to inverter 30.

  The battery B, which is a direct current power source, includes a secondary battery such as a nickel metal hydride battery or a lithium ion battery. The battery B may be a fuel cell or a capacitor. Battery B outputs the generated DC voltage to boost converter 10 and is charged by the DC voltage output from boost converter 10.

  The inverters 20 and 30 are provided with a plurality of switching elements. The switching element is a semiconductor element such as an IGBT, a bipolar transistor, a thyristor, or a MOS-FET. The inverters 20 and 30 are controlled by the control device 60.

  Capacitor C1 is connected between power supply line PL1 and ground line SL, and reduces the influence on battery B and boost converter 10 due to voltage fluctuation. Capacitor C2 is connected between power supply line PL2 and ground line SL, and reduces the influence on inverters 20 and 30 and boost converter 10 due to voltage fluctuation.

  Boost converter 10 boosts the DC voltage from battery B based on control signal PWC from control device 60, and outputs the boosted voltage to power supply line PL2. Boost converter 10 steps down DC voltage received from inverters 20 and 30 via power supply line PL2 to voltage level of battery B based on control signal PWC from control device 60, and charges battery B.

  Inverter 20 converts voltage Vm of power supply line PL2 into an AC voltage based on control signal PWM1 from control device 60, and outputs the AC voltage to motor generator MG1. Thereby, motor generator MG1 is driven to generate a desired torque. Inverter 20 converts AC voltage generated by motor generator MG1 into DC voltage based on control signal PWM1 from control device 60, and outputs the converted AC voltage to power supply line PL2.

  Inverter 30 converts voltage Vm received from power supply line PL2 into an AC voltage based on control signal PWM2 from control device 60, and outputs the AC voltage to motor generator MG2. Thereby, motor generator MG2 is driven to generate a desired torque. Further, inverter 30 converts the AC voltage output from motor generator MG2 into an AC voltage based on control signal PWM2 from control device 60 during regenerative braking of motor generator MG2, and converts the converted DC voltage to a power line. Output to PL2.

  Current sensor 70 detects motor current MCRT1 flowing through motor generator MG1 and outputs the detected motor current MCRT1 to control device 60. Current sensor 72 detects motor current MCRT2 flowing through motor generator MG2, and outputs the detected motor current MCRT2 to control device 60.

  Control device 60 receives torque command values TR1, TR2 for motor generators MG1, MG2 from output torque control device 80, and receives motor rotational speeds MRN1, MRN2 from an external ECU (not shown). Control device 60 also receives DC voltage Vb as voltage of battery B from voltage sensor 76, and receives output voltage Vm of boost converter 10 (ie, input voltage to inverters 20 and 30) from voltage sensor 78. Furthermore, control device 60 receives motor current MCRT1 from current sensor 70 and receives motor current MCRT2 from current sensor 72.

  Based on output voltage Vm, torque command value TR1 and motor current MCRT1, control device 60 generates control signal PWM1 for controlling the switching element of inverter 20 when inverter 20 drives motor generator MG1, The generated signal PMW1 is output to the inverter 20.

  Control device 60 generates control signal PWM2 for controlling the switching element of inverter 30 when inverter 30 drives motor generator MG2 based on output voltage Vm, torque command value TR2 and motor current MCRT2. The generated signal PMW2 is output to the inverter 30.

  Further, control device 60, when inverter 20 (or inverter 30) drives motor generator MG1 (or motor generator MG2), DC voltage Vb, output voltage Vm, torque command value TR1 (or TR2), motor rotational speed MRN1. Based on (or MRN2), a control signal PWC for controlling the switching element of boost converter 10 is generated and output to boost converter 10.

  FIG. 2 is a diagram for explaining a cooling device applied to the vehicle drive system 100 shown in FIG. 1.

  In FIG. 2, the vehicle drive system is a cooling device that is a cooling water circulation path 40 that is a fluid for cooling the inverter 20, a water pump 42 that circulates the cooling water, and a heat pump that releases heat of the cooling water to cool it. And a liquid temperature sensor 46 that detects the temperature of the cooling water passing through the inverter 20. The liquid temperature sensor 46 is provided in a place that is not easily affected by heat generated by each module such as a switching element provided in the inverter 20. The liquid temperature sensor 46 may be provided not in the vicinity of the inverter 20 in the circulation path 40 but in the vicinity of the outlet of the cooling water from the radiator 44, for example. The control device 60 acquires the coolant temperature Tw detected by the fluid temperature sensor 46.

  The control device 60 transmits a rotational speed command value DR to the water pump 42. The rotational speed command value DR is usually a constant value set in advance. The control device 60 may transmit a rotational speed command value DR corresponding to the coolant temperature Tw. For example, the temperature range of the cooling water is divided into three ranges of low temperature, medium temperature, and high temperature, and a rotational speed command value DR corresponding to each temperature range is set in advance to correspond to the detected coolant temperature Tw. The rotation speed command value DR set for the temperature range may be transmitted to the water pump 42.

  A cooling device as shown in FIG. 2 is also provided for boost converter 10, inverter 30, motor generators MG1, MG2, and the like. The cooling device may be provided for each cooling target module such as the inverter 20, or a plurality of cooling target modules may be cooled by one cooling device.

  FIG. 3 is a functional block diagram of the output torque control device 80. Note that each module constituting the output torque control device 80 stores a program stored in a storage device (hereinafter simply referred to as a storage device) such as a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk device. It functions by being executed by a central processing unit (CPU). In this embodiment, an example in which the output torque control device 80 is provided separately from the control device 60 will be described. However, the output torque control device 80 may be incorporated in the control device 60. That is, the output torque control device 80 and the control device 60 may be configured as one device. Further, among the modules constituting the output control device 80, only some modules, for example, only the output torque limiting unit 90 described later may be incorporated in the control device 60.

  In FIG. 3, a vehicle speed calculation unit 82 calculates the vehicle speed of the vehicle based on a rotation speed signal acquired from a rotation speed sensor provided on the axle of the drive wheel. The accelerator opening calculation unit 84 calculates the accelerator opening based on the accelerator pedal depression amount signal obtained from an accelerator sensor or the like. The range position acquisition unit 86 acquires the position of the range selected by the driver operating the shift lever or the like. Based on the vehicle speed V, the accelerator pedal opening AP, and the wrench position RP, the output torque command value calculation unit 88, for example, as shown in FIG. 4 prepared in advance for each motor generator MG1, MG2 and each position of the range. Referring to the reference map, basic output torque command values TRo1, TRo2 for motor generators MG1, MG2 are calculated. Further, the output torque command value calculating unit 88 multiplies the basic output torque command values TRo1 and TRo2 by a coefficient α (0 <α ≦ 1) output from an output torque limiting unit 90, which will be described later, to obtain an output torque command value TR1. , TR2 are calculated and output to the control device 60.

  The output torque limiting unit 90 acquires the actual rotational speed R of the water pump 42 from the water pump 42 from, for example, a rotational speed sensor that detects the rotational speed of the motor that drives the water pump 42. Further, the output torque limiting unit 90 specifies a coefficient α corresponding to the acquired actual rotational speed R with reference to a reference map associating the actual rotational speed and the coefficient α as shown in FIG. It outputs to the output torque command value calculation part 88. FIG. 5 shows an example in which only two coefficients are set: a coefficient when the actual rotational speed R is within the predetermined specified range and a coefficient when the actual rotational speed R is not included in the predetermined specified range. However, for example, when a reference map as shown in FIG. 6 is prepared and the actual rotational speed R is not included in the predetermined range, the coefficient α is set linearly according to the actual rotational speed R. May be.

  Conventionally, for example, the output torque control device limits the output torque command value according to the coolant temperature Tw and the element temperature Te of the switching element of the inverter. More specifically, as shown by the solid line 200 in FIG. 7A, the output torque control device reduces the output torque command value when the coolant temperature Tw or the element temperature Te exceeds a predetermined threshold temperature. . On the other hand, in the present embodiment, in addition to the restriction on the coolant temperature Tw or the element temperature Te, in addition, when the actual rotational speed R of the water pump is not included in the predetermined specified range, the actual rotational speed R is determined. The limit is added to the output torque command value. That is, in the present embodiment, the output torque control device 80 sets the output torque command value as indicated by the solid line 210 in FIG. 7B when the actual rotational speed R of the water pump 42 is included in a predetermined specified range. When the actual rotational speed R of the water pump 42 is not included in the predetermined specified range, the output is based on the coefficient α determined according to the actual rotational speed R, as indicated by a broken line 212 in FIG. 7B. Reduce torque command value and output.

  According to the present embodiment, the output torque command value is limited in response to detecting that the flow rate of the cooling water has decreased. For example, even if the cooling efficiency of the cooling device is reduced due to pump failure, air jamming, clogging in the circulation path of the radiator or cooling water, the output torque command value is immediately limited according to this embodiment. The Therefore, overheating of the rotating electrical machine drive system can be reduced. Furthermore, according to the present embodiment, the output torque command value can be restricted before the coolant temperature Tw or the element temperature Te exceeds the threshold temperature. Therefore, compared with the case where only the coolant temperature Tw or the element temperature Te is used as a parameter to limit the output torque command value, overheating of the rotating electrical machine drive system can be prevented more reliably and quickly. Moreover, according to this embodiment, since the overheating of the rotating electrical machine drive system can be prevented more reliably and quickly, for example, the heat resistant structure of the inverter can be simplified. Therefore, the inverter can be reduced in size and weight, and the work man-hours and manufacturing costs can be reduced.

It is a schematic block diagram of the vehicle drive system which concerns on this embodiment. It is a figure for demonstrating the cooling device applied to the vehicle drive system which concerns on this embodiment. It is a functional block diagram of an output torque control device. It is a figure which shows an example of the reference map referred by the output torque control apparatus when calculating a basic output torque command value. It is a figure which shows an example of the reference map referred by the output torque control apparatus, when calculating | requiring the coefficient according to the rotation speed of a water pump. It is a figure which shows an example of the reference map referred by the output torque control apparatus, when calculating | requiring the coefficient according to the rotation speed of a water pump. It is a figure for demonstrating the restriction | limiting of the output torque command value in the past. It is a figure for demonstrating the restriction | limiting of the output torque command value in this embodiment.

Explanation of symbols

  10 boost converter, 20, 30 inverter, 40 circuit, 42 water pump, 44 radiator, 46 fluid temperature sensor, 60 control device, 70, 72 current sensor, 76, 78 voltage sensor, 80 output torque control device, 82 vehicle speed calculation Unit, 84 accelerator opening calculation unit, 86 range position acquisition unit, 88 output torque command value calculation unit, 90 output torque limit unit, 100 vehicle drive system, B battery, C1, C2 capacitor, EGN engine, MG1, MG2 motor generator .

Claims (5)

An output torque command value calculation unit for calculating an output torque command value for the rotating electrical machine drive system;
Rotational speed of the pump for circulating the fluid for cooling the rotary electric machine drive system, when it becomes less than the predetermined lower limit threshold value, the flow rate in the circulation path of the previous SL fluid is determined to not satisfy the predetermined specified flow rate Even when the output torque command value is limited and the rotation speed of the pump exceeds an upper limit threshold value greater than the lower limit threshold value, it is determined that the flow rate of the fluid in the circulation path does not satisfy the predetermined specified flow rate. An output torque limiter for limiting the output torque command value ;
An output torque control device comprising: The output torque control device according to claim 1,
The output torque limiter is
The output torque command value for the rotating electrical machine drive system is reduced by reducing the output torque command value calculated by the output torque command value calculation unit based on a coefficient determined in advance according to the rotation speed of the pump. Restrict,
An output torque control device. A rotating electrical machine drive system;
A cooling device comprising a pump, wherein the pump circulates fluid to cool the rotating electrical machine drive system;
An output torque command value calculation unit that calculates an output torque command value corresponding to a required torque for the rotating electrical machine drive system;
Rotational speed of the pump, when it becomes less than a predetermined lower threshold, before Symbol flow rate of the fluid is determined to not satisfy the predetermined specified flow limits the output torque command value, rotation speed of the pump is the An output torque limiter that limits the output torque command value by determining that the flow rate of the fluid does not satisfy the predetermined specified flow rate even when an upper limit threshold value greater than a lower limit threshold value is exceeded ;
A vehicle drive system comprising: The vehicle drive system according to claim 3, wherein
The output torque limiter is
Limiting the output torque command value for the rotating electrical machine drive system by reducing the output torque command value according to the required torque based on a coefficient predetermined according to the number of rotations of the pump.
A vehicle drive system characterized by that. A vehicle comprising the vehicle drive system according to claim 3 or 4.

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