JP2014208504A - Hybrid vehicle controller - Google Patents

Abstract

In a hybrid vehicle, when a battery is at a low temperature, overcharge can be reliably prevented and an auxiliary device can be operated for as long as possible while preventing overdischarge. A control device (100) for controlling a hybrid vehicle (1) includes a temperature specifying means for specifying a temperature of a battery (30), an SOC specifying means for specifying the SOC of the battery, an internal combustion engine ( 200) When the specified temperature at the time of the start request is less than a predetermined value, the boost converter (21) is stopped when the specified SOC is equal to or higher than the predetermined value, and the specified SOC is the predetermined value. And control means for controlling the relay device (23) to be in an electrically disconnected state. [Selection] Figure 6

Description

  The present invention relates to a technical field of a control device for a hybrid vehicle related to a battery.

  This type of apparatus is disclosed in Patent Document 1. According to the battery control device disclosed in Patent Literature 1, the battery can be reliably warmed up in a short time by charging the regenerative power while prohibiting charging by the driving force of the engine during battery warm-up control. It is said that. A similar device is also disclosed in Patent Document 2.

  In addition, a hybrid vehicle control device has been proposed that uses SMR (System Main Relay) to cool the battery with maximum capacity in battery-less running when an abnormality other than the battery temperature relationship is detected (see Patent Document 3). ). In this device, when an abnormality in the battery temperature is detected, a system-off command signal is output and the vehicle is stopped.

  There has also been proposed a device that limits the target voltage of the boost converter to be lower as the battery temperature is lower (see Patent Document 4).

JP 2008-049877 A JP 2009-0788807 A JP 2008-239079 A JP 2010-172139 A

  Battery charging performance is greatly affected by battery temperature. For example, in a cryogenic environment, the charge limit value (Win) is greatly reduced. In this case, it is necessary to limit the charging of the battery from the viewpoint of preventing overcharging.

  On the other hand, in a hybrid vehicle that generates power using part of the torque of the internal combustion engine and charges the generated power to the battery, the controllability of the charge amount correlates with the controllability of the torque of the internal combustion engine. That is, the minimum value of the charge amount is determined in a manner that is regulated by the throttle diameter of the internal combustion engine. If the minimum charge amount exceeds the battery charge limit value, the battery is overcharged. Therefore, in this type of hybrid vehicle, it is necessary to electrically disconnect the battery from the power generation system when the battery temperature is low.

  On the other hand, in the apparatus disclosed in Patent Document 4, charging to the battery is not prohibited. Therefore, overcharging of the battery cannot be reliably prevented.

  On the other hand, in the devices disclosed in Patent Documents 1 and 2, charging using the internal combustion engine is prohibited when the battery temperature is low, and charging using regenerative power is performed. However, since these also do not prohibit the charging of the battery itself, for example, as a measure for a battery that should be reliably prevented from overcharging, such as a lithium ion battery in which lithium may be deposited during overcharging, Not always enough.

  On the other hand, as disclosed in Patent Document 3, if the SMR is disconnected, the battery can be reliably disconnected from the power generation system, which is desirable from the viewpoint of battery protection. However, in this type of hybrid vehicle, the driving voltages of various auxiliary devices are also generated from the power supply voltage of the battery. Therefore, in this case, it is difficult to drive these auxiliary devices. Further, in order to avoid such a problem, if the auxiliary device is disconnected from the power generation system while allowing the auxiliary device to be driven, the battery may be used during this type of charging prohibition period depending on the operating status of the various auxiliary devices. The SOC (remaining charge capacity index value) of the battery continuously decreases. Therefore, the battery may fall into overdischarge.

  As described above, in the hybrid vehicle that uses the electric power generated by utilizing the torque of the internal combustion engine to charge the battery, it is possible to reliably prevent the battery from being overcharged and to overdischarge the battery when the battery is at a low temperature. Therefore, there is a technical problem that it is difficult to maintain the driving of the auxiliary device as much as possible while preventing it.

  Further, with regard to Patent Documents 1 and 2, since regenerative power converts kinetic energy input from the outside into electrical energy, there is no guarantee that desired power can be obtained at a desired time. Therefore, in these techniques, the possibility that the above-described battery is overdischarged is not excluded.

  The present invention has been made in view of such technical problems, and in a hybrid vehicle, overcharge can be reliably prevented at the time of low temperature of the battery, and the auxiliary device can be used with overdischarge prevented. It is an object of the present invention to provide a control device for a hybrid vehicle that can achieve both a long-term operation.

  In order to solve the above-described problem, a control apparatus for a hybrid vehicle according to the present invention boosts a power supply voltage of the battery by predetermined boost control including switching of a switching state of a battery and switching means based on a boost command voltage. The boost converter that outputs to the load device can be disconnected from the electrical connection between the battery and the boost converter and the electrical connection between the battery and a predetermined auxiliary device in an electrically disconnected state. A control device for a hybrid vehicle that controls a hybrid vehicle including a relay device, an internal combustion engine, and a rotating electrical machine that is a load device capable of powering and regeneration, wherein the temperature specifying means specifies the temperature of the battery. SOC specifying means for specifying the SOC of the battery, and the specified temperature at the start request of the internal combustion engine When the specified SOC is greater than or equal to a predetermined value, the boost converter is stopped, and when the specified SOC is less than the predetermined value, the relay device is placed in the electrically disconnected state. And a control means for controlling (Claim 1).

  In the hybrid vehicle control device according to the present invention, two types of charge prohibition measures applied at a low temperature of the battery are prepared, and these are appropriately switched according to the SOC of the battery.

  That is, when the SOC is equal to or higher than the predetermined value, the boost converter is stopped, and the electrical connection between the power generation system including the rotating electrical machine and the battery is interrupted. In this state, for example, the relay device such as SMR is not disconnected, so that power supply from the battery to the auxiliary device performed via the DC-DC converter or the like is maintained. That is, the driving of the auxiliary device is not limited.

  On the other hand, when the SOC is less than the predetermined value, the relay device is in an electrically disconnected state, and the electrical connection between the power generation system including the rotating electrical machine and the battery is interrupted. In this state, since the electrical connection between the battery and the auxiliary device is also cut off at the same time, the battery is completely in a stand-alone state, and the hybrid vehicle is in a so-called battery-less state. In this state, the SOC of the battery does not fluctuate at all except for slight fluctuations excluding spontaneous discharge. Therefore, the battery can be prevented from falling into an overdischarged state.

  That is, according to the control apparatus for a hybrid vehicle according to the present invention, both reliable prevention of overcharge and operation of the auxiliary equipment over the longest possible time while preventing overdischarge at the time of low temperature of the battery are achieved. It can be done.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic configuration diagram conceptually illustrating a configuration of a hybrid vehicle according to an embodiment of the present invention. It is a schematic block diagram of the hybrid drive device in the hybrid vehicle of FIG. It is a schematic block diagram of PCU in the hybrid vehicle of FIG. It is a block diagram of a pressure | voltage rise control part. It is a block diagram of an inverter control part. 2 is a flowchart of battery protection control in the hybrid vehicle of FIG. 1.

<Embodiment of the Invention>
Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of Embodiment>
First, with reference to FIG. 1, the structure of the hybrid vehicle 1 which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the hybrid vehicle 1.

  In FIG. 1, the hybrid vehicle 1 includes an ECU (Electronic Control Unit) 100, a hybrid drive device 10, a PCU (Power Control Unit) 20, a battery 30, a blower fan 40, and a sensor group 50. It is an example of the "hybrid vehicle" concerning.

  The ECU 100 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like, and is configured to be able to control the operation of each part of the hybrid vehicle 1, and is an example of the “hybrid vehicle control device” according to the present invention. The ECU 100 can execute “battery protection control” to be described later according to a control program stored in the ROM.

  The ECU 100 includes a boost control unit 110 and an inverter control unit 120 that control a later-described boost converter 21 and inverter 22 provided in the PCU 20, respectively. Details of the boost control unit 110 and the inverter control unit 120 will be described later.

  The PCU 20 converts the DC power extracted from the battery 30 into AC power and supplies it to a motor generator MG1 and a motor generator MG2, which will be described later, and converts AC power generated by the motor generator MG1 and the motor generator MG2 into DC power. Inverter 22 (not shown) configured to be able to be supplied to battery 30, the power input / output between battery 30 and each motor generator, or the power input / output between each motor generator (that is, in this case) The control unit is configured to be capable of controlling power transfer between the motor generators without using the battery 30. The PCU 20 is electrically connected to the ECU 100 and its operation is controlled by the ECU 100. The PCU 20 will be described in detail later with reference to FIG.

  The battery 30 is a rechargeable secondary battery unit that functions as a power supply source related to power for powering the motor generator MG1 and the motor generator MG2. The battery 30 has a configuration in which a plurality (for example, several hundreds) of unit battery cells such as lithium ion battery cells are connected in series. The battery 30 is an example of a “battery” according to the present invention.

  The battery 30 is housed in a battery case 31. The battery case 31 is installed in a duct (not shown) installed in the lower part of the rear seat of the hybrid vehicle 1. The duct is an air passage, and the upstream side communicates with the passenger compartment through a predetermined communication port. Such a battery storage mode is an example.

  The blower fan 40 is a blower installed between the battery case 31 and the communication port in the duct described above. The blower fan 40 is configured to guide the air in the vehicle interior into the duct by the rotation of the blade-like member, and the airflow directed from the upstream side to the downstream side with the communication port side as the upstream side in the duct by the blower fan 40. Is formed. The battery 30 accommodated in the battery case 31 is configured to be exposed to this airflow through a vent hole appropriately formed in the battery case 31. Usually, the battery 30 is cooled by this airflow. That is, the blower fan 40 normally functions as a cooling fan.

  The sensor group 50 is a collective name for various sensors that detect the state of the hybrid vehicle 1. The sensor group 50 includes at least a battery temperature sensor 51, an accelerator opening sensor 52, an SOC sensor 53, and a vehicle speed sensor 54.

  The battery temperature sensor 51 is a sensor that detects a battery temperature Tbat that is the temperature of the battery 30. The battery temperature sensor 51 is electrically connected to the ECU 100, and the detected battery temperature Tbat is appropriately referred to by the ECU 100.

  The accelerator opening sensor 52 is a sensor that detects an accelerator opening Ta that is an opening of an accelerator pedal. The accelerator opening sensor 52 is electrically connected to the ECU 100, and the detected accelerator opening Ta is appropriately referred to by the ECU 100.

  The SOC sensor 53 is a sensor that detects the SOC that is the remaining charge capacity of the battery 30. The SOC sensor 53 is electrically connected to the ECU 100, and the detected SOC is appropriately referred to by the ECU 100.

  The vehicle speed sensor 54 is a sensor that detects the vehicle speed V of the hybrid vehicle 1. The vehicle speed sensor 54 is electrically connected to the ECU 100, and the detected vehicle speed V is appropriately referred to by the ECU 100.

  The hybrid drive device 10 is a power train of the hybrid vehicle 1. Here, the detailed configuration of the hybrid drive apparatus 10 will be described with reference to FIG. FIG. 2 is a schematic configuration diagram conceptually showing the configuration of the hybrid drive apparatus 10. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  The hybrid drive device 10 includes an engine 200, a power split mechanism 300, an input shaft 400, a drive shaft 500, a speed reduction mechanism 600, a motor generator MG1 (hereinafter referred to as “MG1” where appropriate), a motor generator MG2 (hereinafter referred to as “MG2” as appropriate). For short).

  The engine 200 is a gasoline engine that functions as a main power source of the hybrid vehicle 1 and is an example of the “internal combustion engine” according to the present invention.

  The engine 200 includes a piston that reciprocates inside the cylinder in response to an explosive force generated when the air-fuel mixture burns in a combustion chamber formed inside the cylinder. The reciprocating motion of the piston is converted into the rotational motion of the crankshaft via the connecting rod, and is taken out from the input shaft 400 connected to the crankshaft. Note that the detailed configuration of the engine 200 is omitted here because it has a low relationship with the present invention. Although the engine 200 is a gasoline engine here, there are a wide variety of practical aspects that can be taken by the “internal combustion engine” according to the present invention. For example, the “internal combustion engine” according to the present invention is free in fuel type, cylinder arrangement, number of cylinders, fuel supply mode, valve system configuration, intake / exhaust system configuration, and the like.

  Motor generator MG1 is a motor generator that is an example of a “rotary electric machine” according to the present invention, which has a power running function that converts electrical energy into kinetic energy and a regeneration function that converts kinetic energy into electrical energy.

  Motor generator MG2 is a motor generator having a larger physique than motor generator MG1, and, like motor generator MG1, has a power running function that converts electrical energy into kinetic energy and a regeneration function that converts kinetic energy into electrical energy. It is another example of the “rotary electric machine” according to the present invention provided.

  The motor generators MG1 and MG2 are configured as synchronous motor generators and include, for example, a rotor having a plurality of permanent magnets on the outer peripheral surface and a stator wound with a three-phase coil that forms a rotating magnetic field. You may have the structure of.

  The power split mechanism 300 is a known planetary gear mechanism that includes a plurality of rotating elements that have a differential action with respect to each other.

  The power split mechanism 300 is disposed between the sun gear S1 provided at the center, the ring gear R1 provided concentrically on the outer periphery of the sun gear S1, and the sun gear S1 and the ring gear R1. A plurality of pinion gears (not shown) that revolve while rotating, and a carrier C1 that supports the rotation shaft of each pinion gear.

  Sun gear S1 is a reaction force element for bearing reaction torque against engine torque Te, which is output torque of engine 200, and is fixed to an output rotation shaft to which the rotor of motor generator MG1 is fixed. Therefore, the rotational speed of sun gear S1 is equivalent to MG1 rotational speed Nmg1, which is the rotational speed of motor generator MG1.

  The ring gear R1 is an output element of the power split mechanism 300, and is connected to a drive shaft 500, which is a power output shaft of the power split mechanism 300, in a manner sharing its rotational axis. The drive shaft 500 is indirectly connected to the drive wheels DW of the hybrid vehicle 1 through a differential or the like.

  The carrier C1 is connected to the input shaft 400 connected to the crankshaft of the engine 200 via the torsion damper TDP so as to share the rotation shaft, and the rotation speed is equal to the engine speed NE of the engine 200. Is equivalent.

  In the power split mechanism 300, the engine torque Te supplied from the engine 200 to the input shaft 400 is transferred to the sun gear S1 and the ring gear R1 by the carrier C1 with the predetermined ratio (the gear ratio between the gears). It is possible to divide the power of the engine 200 into two systems.

  At this time, in order to make the operation of the power split mechanism 300 easy to understand, when the gear ratio ρ as the number of teeth of the sun gear S1 with respect to the number of teeth of the ring gear R1 is defined, the engine torque Te is applied from the engine 200 to the carrier C1. In this case, the torque Tes acting on the sun gear S1 is expressed by the following equation (1), and the direct torque Ter appearing on the drive shaft 500 is expressed by the following equation (2).

Tes = −Te × ρ / (1 + ρ) (1)
Ter = Te × 1 / (1 + ρ) (2)
Deceleration mechanism 600 is a planetary gear mechanism that includes rotation elements of sun gear S2, ring gear R2, pinion gear (not shown), and carrier C2 interposed between drive shaft 500 and motor generator MG2.

  In reduction mechanism 600, sun gear S2 is fixed to an output rotation shaft fixed to the rotor of motor generator MG2. The carrier C2 is fixed to the outer case of the hybrid drive device 10 so as not to rotate. Further, the ring gear R <b> 2 is connected to the drive shaft 500. In such a configuration, the speed reduction mechanism 600 can transmit the rotational speed Nmg2 of the motor generator MG2 to the drive shaft 500 while reducing the speed according to the speed ratio determined according to the gear ratio of each rotation element (gear).

  It should be noted that the configuration of speed reduction mechanism 600 is merely one form that can be adopted by a mechanism that decelerates the rotation of motor generator MG2, and this type of speed reduction mechanism can have various forms in practice. Further, this type of reduction mechanism is not necessarily provided in the hybrid drive device. That is, motor generator MG2 may be directly connected to drive shaft 500.

  Next, the configuration of the PCU 20 according to the present embodiment will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the PCU 20.

  In FIG. 3, the PCU 20 includes a boost converter 21, an inverter 22, an SMR 23, and a DC-DC converter 24.

  Boost converter 21 is a booster that boosts the power supply voltage of battery 30 to a boost command voltage suitable for driving motor generators MG1 and MG2, which are load devices.

  In boost converter 21, one end of reactor L1 is connected to a positive line (not shown) connected to the positive electrode of battery 30, and the other end is an intermediate point between switching element Q1 and switching element Q2, that is, a switching element. It is connected to a connection point between the emitter terminal of Q1 and the collector terminal of switching element Q2.

  The switching elements Q1 and Q2 are switching means connected in series between the positive electrode line and a negative electrode line (not shown) connected to the negative electrode of the battery 30. The collector terminal of the switching element Q1 is connected to the positive electrode line, and the emitter terminal of the switching element Q2 is connected to the negative electrode line. The diodes D1 and D2 are rectifying elements that allow only current from the emitter side to the collector side in each switching element.

  In this embodiment, the switching element is composed of a switching element Q1 on the higher potential side than the connection point with the end of the reactor L1, and a switching element Q2 on the lower potential side. A boost converter is configured. However, the configuration of such a switching element is an example, and the boost converter may be a one-arm type boost converter including only the switching element Q2 in FIG.

  The switching elements Q1 and Q2 and the switching elements (Q3 to Q8 and Q13 to Q18) of the inverter 22 are configured as, for example, IGBTs (Insulated Gate Bipolar Transistors), power MOS (Metal Oxide Semiconductor) transistors, or the like.

  The capacitor C is a capacitor connected between the positive electrode line and the negative electrode line. The voltage across the capacitor C, that is, the potential difference VH between the positive electrode line and the negative electrode line is the output voltage of the boost converter 21.

  The inverter 22 includes an inverter circuit 22A for driving MG1 and an inverter circuit 22B for driving MG2.

  The inverter circuit 22A includes a U-phase arm (not shown) including a p-side switching element Q3 and an n-side switching element Q4, a V-phase arm (not shown) and a p-side switching including a p-side switching element Q5 and an n-side switching element Q6. The power converter includes a W-phase arm (reference numeral omitted) including an element Q7 and an n-side switching element Q8. Each arm of the inverter 22A is connected in parallel between the positive electrode line and the negative electrode line.

  The switching elements Q3 to Q8 are connected to rectifying diodes D3 to D8 that allow current to flow from the emitter side to the collector side, similarly to the switching elements Q1 and Q2. Further, an intermediate point between the p-side switching element and the n-side switching element of each phase arm in inverter circuit 22A is connected to each phase coil of motor generator MG1.

  The inverter circuit 22B has a configuration similar to that of the inverter circuit 22A. As switching elements, the p-side switching elements Q13, Q15, and Q17 are switched for the u-phase, v-phase, and w-phase, and the n-side switching is performed. Elements Q14, Q16 and Q18 are provided. The same applies to the rectifying diode.

  The boost converter 21 and the inverter 22 constitute an example of a “power converter” according to the present invention.

  The SMR 23 is a relay device that can cut off the electrical connection between the battery 30 and the boost converter 21 and the DC-DC converter 24 in an electrically disconnected state. The SMR 23 is electrically connected to the ECU 100, and the operation state is controlled by the ECU 100.

  Note that the boost converter 21, the inverter 22, and a DC-DC converter 24 described later are electrically connected to the battery 30 via the SMR 23. When the SMR 23 is in an electrically disconnected state, the battery 30 in the hybrid vehicle 1 is used. All the load devices that use the power supply source as a power source become unusable. However, for auxiliary equipment such as the above-described blower fan 40 and electric auxiliary equipment that are necessary for operation control of the engine 200, such as a spark plug, which is relatively low in power consumption, the motor generator generates power using the engine torque. It can be covered by such generated power.

  The DC-DC converter 24 is a device that converts the power supply voltage of the battery 30 into a drive voltage of the auxiliary device. Auxiliary equipment includes, for example, electric power steering devices, rudder angle control devices such as VGRS (Variable Gear Ratio Steering), air conditioners and air purifiers, audio and car navigation devices, headlights, winkers, etc. , Brake lamps, tail lamps, valve-operated devices such as cam-by-wire, electric sliding doors and electric seats, power windows, electric retractable mirrors, ABS (Anti-lock Braking System), VSC (Vehicle Stability Control) and other PCS (Pre Crush) safety System) and the above-mentioned blower fan 40, etc.

  The DC-DC converter 24, for example, once converts the power supply voltage of the battery 30 into an AC voltage, transforms the AC voltage into a voltage value for driving auxiliary equipment (for example, 12V), and then rectifies and converts it to a DC voltage again. It becomes the composition to convert.

  Boost converter 21 is controlled by boost controller 110 in ECU 100. Here, the configuration of the boost control unit 110 will be described with reference to FIG. FIG. 4 is a block diagram of the boost control unit 110. In the figure, the same reference numerals are given to the same portions as those in FIG. 3, and the description thereof will be omitted as appropriate.

  4, the boost control unit 110 includes an inverter input calculation unit 111, an adder / subtractor 112, a voltage control calculation unit 113, a carrier generation unit 114, and a comparator 115. Further, the boost control unit 110 is configured to be able to execute boost control according to a control program stored in advance in the ROM.

  The boost control is control for boosting the voltage between the positive electrode line and the negative electrode line, that is, the output voltage VH to be higher than the power supply voltage of the battery 30 based on the converter control signal PWC. In step-up control, if output voltage VH is lower than target value VHtg (also referred to as VH command value), on-duty of switching element Q2 is relatively increased, and the positive line flows from battery 30 side to inverter 300 side. The current can be increased, and the output voltage VH can be increased. On the other hand, if the output voltage VH is higher than the target value VHtg, the on-duty of the switching element Q1 is relatively increased, and the current flowing through the positive line from the inverter 300 side to the battery 30 side can be increased, and the output voltage VH Can be reduced.

  Inverter input calculation unit 111 is a circuit that sets target value VHtg of output voltage VH of boost converter 200. Target value VHtg is determined such that system loss Lsys, which is a loss of the entire power system including boost converter 200, inverter 300, and motor generator MG, is minimized.

  The addition / subtraction unit 112 subtracts the detected value of the output voltage VH from the target value VHtg and outputs the subtraction result to the voltage control calculation unit 113. When the voltage control calculation unit 113 receives a subtraction result obtained by subtracting the detection value of the output voltage VH from the target value VHtg from the addition / subtraction unit 112, the voltage control calculation unit 113 calculates a control amount for making the output voltage VH coincide with the target value VHtg. At this time, for example, a known PI control calculation including a proportional term (P term) and an integral term (I term) is used. The voltage control calculation unit 113 outputs the calculated control amount to the comparator 115 as a voltage command value.

  On the other hand, the carrier generation unit 114 generates a carrier signal composed of a triangular wave and sends it to the comparator 115. In the comparator 115, the voltage command value supplied from the voltage control calculation unit 113 is compared with this carrier signal, and the above-described converter control signal PWC whose logic state changes according to the magnitude relation of the voltage value is generated. The The generated converter control signal PWC is output to switching elements Q1 and Q2 of boost converter 200. The boost control unit 110 is configured as described above.

  The configuration illustrated in FIG. 2 is a circuit configuration that realizes voltage control, but the control mode of the boost converter 200 is not limited to such voltage control.

  Next, the configuration of the inverter control unit 120 will be described with reference to FIG. FIG. 5 is a block diagram of the inverter control unit 120. In the figure, the same reference numerals are given to the same portions as those in the above-described drawings, and the description thereof will be omitted as appropriate. In FIG. 5, for simplicity of explanation, the concept of motor generator MG including motor generator MG <b> 1 and motor generator MG <b> 2 is used as an electrical load connected to inverter 22.

  In FIG. 5, the inverter control unit 120 includes a current command conversion unit 121, a current control unit 122, a two-phase / three-phase conversion unit 123, a three-phase / two-phase conversion unit 124, a carrier generation unit 114 (shared with the boost control unit 110). And PWM converter 125.

  Current command conversion unit 121 generates two-phase current command values (Idtg, Iqtg) based on torque command value TR of motor generator MG.

  On the other hand, the inverter 300 supplies the v-phase current Iv and the w-phase current Iw to the three-phase / 2-phase converter 124 as feedback information. In the three-phase / two-phase converter 124, the three-phase current value is converted from the v-phase current Iv and the w-phase current Iw into a two-phase current value composed of the d-axis current Id and the q-axis current Iq. The converted two-phase current value is sent to the current control unit 122.

  In the current control unit 122, based on the difference between the two-phase current command value generated in the current command conversion unit 121 and the two-phase current values Id and Iq received from the three-phase / two-phase conversion unit 124, d A two-phase voltage command value composed of the shaft voltage Vd and the q-axis voltage is generated. The generated two-phase voltage command values Vd and Vqh are sent to the two-phase / three-phase converter 123.

  In the two-phase / three-phase converter 123, the two-phase voltage command values Vd and Vq are converted into the three-phase voltage command values Vu, Vv, and Vw. The converted three-phase voltage command values Vu, Vv, and Vw are sent to the PWM conversion unit 125.

  Here, the PWM conversion unit 125 is configured to receive a carrier Car having a predetermined carrier frequency fcar from the carrier generation unit 114, and the carrier Car and the converted three-phase voltage command values Vu, Vv, and Vw. Compare the magnitude relationship with. Further, the PWM conversion unit 125 generates u-phase switching signals Gup and Gun, v-phase switching signals Gvp and Gvn, and w-phase switching signals Gwp and Gwn and changes the logic state according to the comparison result to the inverter 22. Supply.

  More specifically, among the switching signals corresponding to each phase, the signal with the identifier “p” added is the p-side switching element (Q3, Q5 and Q7 and Q13, Q15 and Q17) is a drive signal for driving, and a signal with an identifier “n” is used to drive the n-side switching elements (Q4, Q6 and Q8 and Q4, Q6 and Q18) among the switching elements of each phase. This means a drive signal for

  Here, in particular, in the comparison between the carrier Car and each phase voltage command value, when each phase voltage command value matches the carrier Car from a value smaller than the carrier Car, a switching signal for turning on the p-side switching element is generated. The Further, when each phase voltage command value matches the carrier Car from a value larger than the carrier Car, a switching signal for turning on the n-side switching element is generated. That is, the switching signal is a signal that is turned on and off, and one of the p-side and n-side switching elements is always on and the other is off.

  When inverter 22 changes or is maintained in the driving state of each switching element defined by each phase switching signal, motor generator MG is driven according to the circuit state corresponding to the changed or maintained driving state. It has a configuration. Such a control mode of the inverter 300 is a so-called PWM control mode.

  In general, the motor generator MG for driving the vehicle often uses well-known overmodulation control and rectangular wave control in addition to the PWM control described above. Also in the motor drive system 10 according to the present embodiment, the control mode of the inverter 22 is appropriately switched according to the traveling condition of the vehicle.

<Operation of Embodiment>
Next, the operation of this embodiment will be described.

<Driving mode of hybrid vehicle 1>
The hybrid vehicle 1 has an HV travel mode and an EV travel mode as travel modes that define a power transmission mode between the hybrid drive device 10 and the drive wheels DW.

  In the HV traveling mode, by using the power split action of the power split mechanism 300, the direct drive torque Ter that is a part of the engine torque Te and the MG2 torque Tmg2 that is the output torque of the motor generator MG2 are cooperatively driven. This is a travel mode that acts on the vehicle. In the HV traveling mode, electric power regeneration, that is, power generation is also performed by MG1 torque Tmg1 which is output torque of motor generator MG1 using reaction force torque Tes which is another part of engine torque Te.

  At this time, the operating point of the engine 200 (the operating condition defined by the engine speed NE and the engine torque Te) is an electric CVT (Continuously Variable Transmission) of the hybrid drive device 10 using the MG1 torque Tmg1 as a reaction torque. It can be set freely depending on the function. The operating point of the engine 200 is controlled to an optimum fuel efficiency operating point at which the fuel consumption rate (fuel efficiency) of the engine 200 is minimized as a preferred embodiment.

  On the other hand, the MG2 torque Tmg2 is basically controlled to compensate for the shortage of the direct torque Tor with respect to the drive shaft required torque required for the drive shaft 500. That is, in the HV traveling mode, cooperative control between the MG2 torque Tmg2 and the engine torque Te is performed.

  For example, in this cooperative control, the power generation amount of motor generator MG1 and the discharge amount of motor generator MG2 or further the discharge amount of the auxiliary device are set so that the SOC of battery 30 is maintained at the target SOC as the target value. Constantly adjusted. For example, if the SOC of the battery 30 is higher than the target SOC, the ratio of the MG2 torque Tmg2 to the drive shaft required torque is increased, and the power balance is inclined toward the discharge side. Conversely, if the SOC is lower than the target SOC, the ratio is reduced. As a result, the power balance is inclined toward the charging side.

  On the other hand, the EV travel mode is a travel mode in which only the MG2 torque Tmg2 is applied to the drive shaft 500 and the hybrid vehicle 1 is traveled only by the power of the motor generator MG2. In the EV traveling mode, the engine 200 is basically in the engine stopped state (in some cases, the minimum engine operation for supplying power to the auxiliary device may be performed), so that the fuel consumption is zero, or It is so small that it can be ignored. However, since the EV traveling mode is a traveling mode inclined toward the discharge side in terms of the power balance of the battery 12, the SOC of the battery 30 basically continues to decrease. Therefore, whether or not the EV traveling mode can be executed is determined in consideration of the SOC of the battery 30.

<Details of battery protection control>
The charge / discharge characteristics of the battery 30 change according to the battery temperature Tbat. In short, whether the battery temperature Tbat is too high or too low, the charge limit value Win (allowable charge amount per hour) and the discharge limit value Wout (allowable discharge amount per time) of the battery 30 tend to be small. is there.

  Here, since the blower fan 40 described above functions as a cooling fan, the battery 30 rarely falls into an extremely high temperature state, but the battery 30 often falls into an extremely low temperature state during a cold start or the like. .

  Therefore, the battery 30 needs to be protected from overcharge and overdischarge particularly at low temperatures. In particular, in a battery composed of a lithium ion battery such as the battery 30, lithium may be deposited during overcharging, and it is necessary to reliably prevent overcharging. Such a battery protection request is satisfied in the battery protection control executed by the ECU 100.

  Here, the details of the battery protection control will be described with reference to FIG. FIG. 6 is a flowchart of battery protection control. The battery protection control is basically a control that is always executed, and is restarted after a predetermined period of time has elapsed even if it is once terminated.

  In FIG. 6, the ECU 100 determines whether or not the battery temperature Tbat is lower than the reference value T1 and there is an engine start request (step S101).

  At this time, the ECU 100 acquires the battery temperature Tbat detected by the battery temperature sensor 51 (that is, an example of the operation of the “temperature specifying unit”), and determines whether or not the battery temperature Tbat is less than the reference value T1. . The reference value T1 is an adaptive value determined experimentally in advance, and the charge limit value Win is a minimum value of the power generation amount of the motor generator MG1 using the engine torque, or a value in the vicinity of the minimum value. Is the value.

  The power generation action of the motor generator MG1 performed using a part of the engine torque is realized by outputting a reaction torque corresponding to Tes, which is a part of the engine torque, from the motor generator MG1. Therefore, the control accuracy of the power generation amount of motor generator MG1 depends on the control accuracy of torque of engine 200.

  Here, the minimum value of the engine torque that ensures controllability is determined, for example, by the valve diameter of a throttle valve that controls the intake air amount. Therefore, if no measures are taken in a low temperature region where the charging limit value Win is excessively small, the power generation amount may exceed the charging limit value Win, and the battery 30 may be overcharged. The reference value T1 is a value set to prevent such overcharging. The relationship between the battery temperature Tbat, the charge limit value Win, and the discharge limit value Wout is mapped in advance and stored in the ROM.

  On the other hand, the engine start request is a request for starting the engine 200, and is a request that always occurs in a situation where the operation of the engine 200 is required, including a state where the engine 200 has already been started. The presence or absence of an engine start request in the hybrid vehicle is the basis of operation control in the hybrid vehicle, and various known determination methods can be applied.

  For example, the required driving force Ft of the hybrid vehicle 1 is calculated from a preset required driving force map based on the accelerator opening degree Ta detected by the accelerator opening sensor 52 and the vehicle speed V detected by the vehicle speed sensor 54. Is done. Further, the required output of the hybrid vehicle 1 is calculated based on the calculated required driving force Ft and the vehicle speed V. If this calculated required output exceeds the upper limit output of motor generator MG2 capable of supplying torque to drive shaft 500 (for example, determined by discharge limit value Wout), start of engine 200 is required. Further, if the SOC of the battery 30 is insufficient, the engine 200 is required to start for charging the battery 30. The conditions for generating the engine 200 start request may be specifically determined individually.

  When the battery temperature Tbat is equal to or higher than the reference value T1 or when there is no engine start request (step S101: NO), normal control is performed (step S113), and the battery protection control ends. Note that the battery protection control is started again after a predetermined interval as described above.

  The normal control means, for example, control related to the above-described HV traveling mode, EV traveling mode, and the like. That is, the case where step S101 branches to the “NO” side means a situation in which special protection measures (here, steps S104 to S112) of the battery 30 are not required at extremely low temperatures.

  When the battery temperature Tbat is less than the reference value T1 and there is an engine start request (step S101: YES), the ECU 100 starts the engine 200 (step S102). Engine 200 is started by supplying cranking torque (in this case, MG1 is in a power running state) from motor generator MG1.

  When the engine 200 is started, the ECU 100 determines whether or not the engine 200 has been started (step S103). If the engine 200 has not been started (step S103: NO), the ECU 200 according to step S102 is started. Start control continues. On the other hand, when the start of engine 200 is completed (step S103: YES), the SOC of battery 30 detected by SOC sensor 53 is referred to and it is determined whether or not the SOC of battery 30 is larger than reference value α (step S104). ).

  The reference value α is a determination reference value used for selecting one of the two types of battery protection measures determined in advance by adaptation. There is no significant limitation on the setting of the reference value α, and the reference value α is, for example, a lower limit value for control in normal SOC control (the SOC is controlled not to interrupt the lower limit value) or the lower limit value. It is set to a slightly high value. For example, the reference value α may be set to a value of about 25 to 50 (%).

  When the SOC of battery 30 is greater than reference value α (step S104: YES), ECU 100 stops boost converter 21 (step S105). Stop of boost converter 21 means, for example, stop of switching elements Q1 and Q2. When boost converter 21 is stopped, battery 30 is no longer charged.

  On the other hand, driving of motor generators MG1 and MG2 is ensured to some extent by output voltage VH held by capacitor C.

  For example, output voltage VH decreases with time if the power balance of the load device of boost converter 21 including motor generators MG1 and MG2 is inclined toward the discharge side. Further, if the power balance is inclined to the charging side, it increases with time. Further, if the power balance is close to zero, the value at the time when the boost converter 21 is stopped may substantially remain.

  Therefore, when a so-called battery-less travel (a kind of series hybrid travel) in which the motor generator MG2 travels with the electric power generated by the motor generator MG1 is realized as a kind of retreat travel, the decrease in the output voltage VH is slowed down. Can be made. In the period in which boost converter 21 is stopped, for example, such battery-less traveling or traveling using the directly achieved amount of engine torque Te is performed.

  When boost converter 21 is stopped, ECU 100 operates blower fan 40 as a measure for raising the temperature of battery 30 (step S106). The blower fan 40 can be used for cooling the battery 30 if the battery 30 is hotter than the room temperature, but can be used for warming up the battery 30 if the battery temperature Tbat is lower than the room temperature.

  Steps S <b> 105 and S <b> 106 are a first protection process for the battery 30. In the first protection process, the battery 30 and the power generation system including the inverter 22 and each motor generator are disconnected by stopping the boost converter 21, so that charging of the battery 30 is reliably prevented. . On the other hand, since power supply from the battery 30 to the DC-DC converter 24 is not prohibited, the driving of the auxiliary device is maintained as much as possible by the drive voltage obtained via the DC-DC converter 24.

  When warming up of the battery 30 by the blower fan 40 is started, the ECU 100 determines whether or not the battery temperature Tbat is a reference value T2 (T2 ≧ T1) (step S107). The reference value T2 is a value that is greater than or equal to the reference value T1. For example, when the reference value T1 includes a sufficient margin, the reference value T2 and the reference value T1 may be equal. Conversely, when the reference value T1 is set near the minimum value of the power generation amount of the motor generator MG1, the reference value T2 is preferably set to a value higher than the reference value T1.

  When battery temperature Tbat is below reference value T2 (step S107: NO), the process returns to step S104. This is because the SOC of the battery 30 tends to decrease because the power supply to the auxiliary device is continued in a state where charging to the battery 30 is prohibited.

  When battery temperature Tbat becomes higher than reference value T2 (step S107: YES), the process proceeds to step S113, and normal control is performed. In other words, measures specialized for battery protection are released. In the state where the processing has shifted to step S113, the charging limit value Win is larger than the control start time due to the temperature rise of the battery 30, and it is possible to reliably prevent overcharging of the battery 30 under normal control mode. it can.

  Here, the process is returned to step S104 when the battery temperature Tbat is equal to or lower than the reference value T2, but the battery temperature Tbat is higher than the reference value T2 during the execution period of the first protection process. It is a transitional period until. In view of this point, when step S107 branches to the “NO” side, the process may return to step S105, and the process may be substantially put into a standby state in a state where the temperature increase of the battery 30 is promoted.

  In step S104, when the SOC of the battery 30 is equal to or less than the reference value α (step S104: NO), the ECU 100 starts a second protection process related to the protection of the battery 30. That is, the ECU 100 controls the SMR 23 to be in an electrically disconnected state (step S108). And the battery warm-up by the ventilation fan 40 is accelerated | stimulated similarly to a 1st protection process (step S109). However, in the second protection process, the blower fan 40 is driven to the maximum so that the maximum wind force can be obtained.

  In the second protection process, since the SMR 23 is in an electrically disconnected state, various auxiliary devices in which the battery 30 is connected to the power generation system including the inverter 22 and each motor generator via the DC-DC converter 24. And electrically disconnected from both. Therefore, the battery 30 is preferably protected.

  When the warming-up of the battery 30 by the blower fan 40 is started, the ECU 100 determines whether or not the battery temperature Tbat is a reference value T2 (T2 ≧ T1), similarly to step S107 (step S110).

  When the battery temperature Tbat is equal to or lower than the reference value T2 (step S110: NO), the process is returned to step S108, and the process is substantially in a standby state.

  When battery temperature Tbat becomes higher than reference value T2 (step S110: YES), ECU 100 stops boost converter 21 as in step S105 (step S111). After the boost converter 21 is stopped, the SMR 23 is connected (step S112).

  When the SMR 23 is connected, the process shifts to normal control (step S113). It should be noted that the boost converter 21 is stopped at the start of step S113 through either step S107 or step S112. Therefore, in step S113, the operation of boost converter 21 is first restarted. Battery protection control proceeds in this way.

  As described above, according to the battery protection control according to the present embodiment, when the engine start is requested when the battery 30 is at a low temperature, the first or second protection process is started according to the SOC of the battery 30. The first and second protection processes differ in whether or not power can be supplied to the DC-DC converter 24. That is, while the SOC is sufficient, the first protection process maintains the electrical connection between the battery 30 and the auxiliary device via the SMR 23, while the battery 30 and the power generation load via the boost converter 21 are maintained. Is disconnected from the electrical connection. Therefore, it is possible to continue driving the auxiliary device as much as possible while reliably preventing the battery 30 from being charged. On the other hand, when there is no margin in the SOC or when there is no margin in the SOC from the beginning, the SMR 23 is brought into an electrically disconnected state by the second protection process. Therefore, it is possible to reliably prevent the battery 30 from being over-discharged by driving the auxiliary device while reliably preventing the battery 30 from being charged.

  That is, according to the present embodiment, when the battery 30 is at a low temperature, reliable prevention of overcharging and operation of the auxiliary device for as long as possible with overdischarge prevented are preferably achieved. is there.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and control of a hybrid vehicle involving such a change. The apparatus is also included in the technical scope of the present invention.

  The present invention is applicable to battery protection for hybrid vehicles.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 10 ... Hybrid drive device, 20 ... PCU, 30 ... Battery, MG1, MG2 ... Motor generator, 100 ... ECU, 200 ... Engine, 300 ... Power split mechanism, 400 ... Input shaft, 500 ... Drive shaft, 600 ... Deceleration mechanism.

Claims (1)

Battery,
A boost converter that boosts the power supply voltage of the battery by a predetermined boost control including switching of the switching state of the switching means based on the boost command voltage and outputs the boosted voltage to the load device;
A relay device capable of interrupting an electrical connection between the battery and the boost converter and an electrical connection between the battery and a predetermined auxiliary device in an electrical disconnection state;
An internal combustion engine;
A hybrid vehicle control device that controls a hybrid vehicle including a rotating electrical machine that is a load device capable of power running and regeneration,
Temperature specifying means for specifying the temperature of the battery;
SOC specifying means for specifying the SOC of the battery;
When the specified temperature is less than a predetermined value when the internal combustion engine is requested to start, the boost converter is stopped when the specified SOC is equal to or higher than a predetermined value, and the specified SOC is less than the predetermined value And a control means for controlling the relay device to the electrically disconnected state.

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