JP2008110700A - Power supply system of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the low-temperature startability of a vehicle and to increase the capacity of a low voltage power supply, in a power supply system of a hybrid vehicle. <P>SOLUTION: The power supply system 10 of the hybrid vehicle has a function of supplying power to a motor 56 through a PCU 54 in order to start an engine 58 and supplying power to a 14V-system load 50 and 42V-system load 52. The power supply system 10 comprises a 200V-system high voltage battery 12, a 12V-system battery 18, a 42V-system battery 22, a 14V-system DC/DC converter 16 capable of only reducing voltage, and a bidirectional 42V-system DC/DC converter 20 capable of both reducing voltage and rising voltage. A control section 40, according to the temperature related to the engine 58, switches the operation of the 42V-system DC/DC converter 20 to voltage rising mode when it is low temperature and the 42V-system load 52 does not operate, operation stop mode when it is low temperature and the 42V-system load 52 operates, or voltage reducing mode when it is not low temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply system for a hybrid vehicle, and more particularly to a power supply system for a hybrid vehicle having a high voltage battery for supplying electric power for driving the vehicle and a low voltage battery for supplying electric power for operating an auxiliary machine.

  A hybrid vehicle includes a rotating machine driven by electric power from a high-voltage battery and an engine, but includes various auxiliary machines and electronic devices that operate with electric power. Since these auxiliary machines and electronic devices are often operated by a low-voltage power source such as a 12V system, for example, a low-voltage power source is mounted on the hybrid vehicle. A typical low voltage power source is a low voltage battery of a 14V secondary battery such as a lead storage battery. The low-voltage battery such as 14V system is supplied with electric power that is stepped down by the DC / DC converter from the high-voltage battery and charged. In addition, a 42V battery may be used as a low-voltage power source. Some vehicles use a 14V system as a low-pressure system and a 42V system as a high-pressure system.

  In addition, since the operating range of the secondary battery has a width, on the other hand, the DC / DC converter connected to them has a relatively constant voltage. A notation may be used. For example, a battery using a secondary battery in the range of 12V to 14V may be referred to as a 14V system as described above, and may be expressed as a 12V system. Similarly, a battery using a secondary battery in the range of 36V to 42V is sometimes referred to as a 36V system in addition to the 42V system as described above.

  Patent Document 1 describes a dual power supply system including a 12V low voltage battery, a 36V, 144V or approximately 300V high voltage battery, and a bidirectional DC-DC converter as a power supply system in a hybrid vehicle. Then, using this bidirectional DC-DC converter, when the engine is started by the generator motor, when the engine is suddenly accelerated by a predetermined electric power or more by the generator motor, and when the engine is in a predetermined period such as idle stop In addition, it is described that the low-voltage battery is charged with electric power larger than that before and after the regenerative braking performed by the generator motor during vehicle braking by transmitting power from the low-voltage battery to the high-voltage battery.

  Patent Document 2 includes a battery having a high voltage terminal of 42 V and a low voltage terminal of 14 V in a vehicle power supply system in which a 14 V system power supply system and a 42 V system power supply system coexist, and a space between the high voltage terminal and the inverter. A power supply system is disclosed in which a high voltage FET and a reverse connection diode are connected, and a low voltage terminal and an inverter are connected by a low voltage FET and a reverse connection diode. Here, the reverse connection diode is arranged so that charging to the high voltage terminal and discharging from the low voltage terminal are always possible. As a result, the vehicle can be operated until the battery remaining rate on the low voltage terminal side decreases, and the battery charge rate on the high voltage terminal side and the battery charge rate on the low voltage terminal side are detected and uninterrupted between them. It is stated that no balance occurs.

  Patent Document 3 discloses a vehicle power supply device capable of connecting a 42V battery for a drive motor for starting or assisting an engine and a 12V battery for an auxiliary machine in a series connection of 42V + 12V by a switch. Yes. Here, when the engine is started by the drive motor, when the engine is assisted, and when the vehicle is decelerating, the regenerative power generation amount is switched to the serial connection when it is greater than or equal to a predetermined value.

  Patent Document 4 discloses battery switching control for a vehicle including a plurality of high-voltage batteries. Then, when driving the traction motor, the voltage value of each high-voltage battery is obtained, and those having a voltage value higher than the minimum required at the time of driving are selected, and the voltage value is low and the remaining capacity is low. The priority of use is determined from the battery, and at the time of traveling regeneration, it is selected whether or not it is a battery that can be used for regenerative charging by the regenerative current from the traveling motor. It is stated that priorities are determined in order.

JP 2002-176704 A JP 2002-10408 A JP 2004-116296 A Japanese Patent Laying-Open No. 2005-237064

  Thus, in the prior art, when a high voltage battery and a low voltage battery are provided, a system for exchanging electric power between them is disclosed.

  By the way, with the evolution of hybrid vehicles, there is an increase in the number of auxiliary machines and electronic devices that are operated by a low-voltage battery, and the required power of the auxiliary machines tends to increase. Therefore, it is necessary to expand the capacity of the low-voltage power supply. As one of the measures, it is conceivable that the low voltage battery is used as a large capacity battery as it is. However, in that case, it is necessary to increase the capacity of the battery, and the capacity and cost increase.

  As another measure, it is conceivable to increase the conversion capacity of a DC / DC converter that steps down from a high-voltage battery to a low-voltage power supply to supply sufficient charging power to the low-voltage battery. In this case, the capacity that can be used for driving the high-voltage battery or the like decreases. A hybrid vehicle uses a rotating machine as an engine starting source in addition to using a rotating machine for driving a vehicle or for regeneration. However, when a large amount of electric power is supplied from a high voltage battery to a low voltage power source, the electric power that can be used for starting the engine is reduced. In particular, the output characteristics of the battery are degraded at low temperatures, and the startability may be degraded. In order to prevent these problems, the capacity of the high-voltage battery can be increased, but the volume and cost are still increased.

  As described above, the conventional technology cannot sufficiently meet the demand for expanding the capacity of the low-voltage power supply.

  An object of the present invention is to provide a power supply system for a hybrid vehicle that can expand the capacity of a low-voltage power supply. Another object is to provide a power supply system for a hybrid vehicle that can improve the cold startability of the vehicle. It is an object of the present invention to provide a power supply system for a hybrid vehicle that can expand the capacity of a low-voltage power supply while improving the low temperature startability of the vehicle. The following means contribute to at least one of these purposes.

  A power supply system for a hybrid vehicle according to the present invention includes a high voltage battery, a drive motor that starts an engine with electric power supplied from the high voltage battery, a 42V battery, and a load that operates with electric power supplied from the 42V battery, A bidirectional 42V DC / DC converter provided between the high voltage battery and the 42V battery, a temperature sensor for detecting a temperature related to the engine, and an operation control of the 42V DC / DC converter according to the temperature detected by the temperature sensor. And a control unit for performing the above.

  In the hybrid vehicle power supply system according to the present invention, the control unit boosts the 42V DC / DC converter to increase the electric power boosted from the 42V battery when the temperature sensor detects a temperature lower than a predetermined temperature. It is preferable to perform control at a low temperature supplied to the drive motor.

  In the hybrid vehicle power supply system according to the present invention, the control unit has means for determining whether or not there is an auxiliary machine that needs to be operated at a low temperature, and there is an auxiliary machine that needs to be operated at a low temperature. It is preferable to perform stop control to stop the operation of the 42V DC / DC converter without performing the low temperature control.

  In the power supply system for a hybrid vehicle according to the present invention, a 14V system battery, a load that operates with power supplied from the 14V system battery, and a 14V system DC / DC provided between the high voltage battery and the 14V system battery. And a DC converter.

  In the power supply system for a hybrid vehicle according to the present invention, the 42V battery is preferably composed of the same unit cell as that of the high-voltage battery.

  With the above configuration, the high-voltage battery is provided with a 42V battery, a 42V bidirectional DC / DC converter provided between the high voltage battery and the 42V battery, and a temperature sensor that detects the temperature of the engine, and the load is 42V. It operates with electric power supplied from the system battery, and operation control of the bidirectional 42V system DC / DC converter is performed according to the engine temperature. The 42V DC / DC converter can step down the power of the high voltage battery and supply it to the low voltage battery, and can step up the power of the low voltage battery to obtain high voltage power. Therefore, sufficient power can be supplied to the load by the former control. In addition to the power from the high-voltage battery, the latter control can also supply the drive motor with the electric power obtained by boosting the electric power of the 42V battery. By performing this control particularly at low temperatures, the engine startability can be improved. be able to.

  Further, when the temperature detected by the temperature sensor is a low temperature equal to or lower than the predetermined temperature, the 42V DC / DC converter is boosted to supply the boosted electric power from the 42V battery to the drive motor. Low temperature startability can be improved.

  Further, it is determined whether or not there is an auxiliary machine that needs to be operated at a low temperature. If there is an auxiliary machine that needs to be operated at a low temperature, the operation of the 42V DC / DC converter is stopped. When the 42V DC / DC converter operates, the power of the high voltage battery is not divided into the charge of the 42V battery. Therefore, the electric power of the high-voltage battery can be sufficiently allocated to start the engine, thereby improving the low-temperature startability of the hybrid vehicle.

  Further, in addition to the 42V system, a 14V system battery, a load that operates with electric power supplied from the 14V system battery, and a 14V system DC / DC converter provided between the high voltage battery and the 14V system battery are provided. Therefore, the capacity of the low-voltage power supply can be expanded. In addition, the capacity of the low-voltage power supply can be increased while improving the low temperature startability of the vehicle.

  Further, the 42V battery is composed of the same unit cells as the unit cells constituting the high voltage battery. Thereby, it is not necessary to construct a special battery system for configuring the 42V battery. For example, when a high voltage battery is configured, a part of the high voltage battery can be a 42V battery, and the configuration is simplified.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the hybrid vehicle is assumed to include a motor and an engine, and one motor is shown in the drawing. However, the hybrid vehicle may have separate rotating machines for driving and for regenerative use. In addition, as the battery, the high voltage battery includes two 200V systems and the low voltage battery includes 14V system and 42V system, but the high voltage battery may be other voltage systems. For example, a 300V high voltage battery may be used. Moreover, it is good also considering only a 42V system as a low voltage battery. Here, the 14V system battery is a secondary battery having an operating range of about 12V to 14V, and the 42V system battery is a generic term for secondary batteries having an operating range of about 36V to 42V.

  FIG. 1 is a diagram showing a configuration of a power supply system 10 for a hybrid vehicle. The power supply system 10 of the hybrid vehicle has a function of supplying electric power to a motor 56 as a vehicle drive source and loads such as auxiliary equipment and electronic equipment. Here, although not shown in FIG. 1 as a component of the power supply system 10 of the hybrid vehicle, a motor 56, an engine 58 connected to the motor 56, a power control unit (PCU) 54 for supplying AC power to the motor 56, A 14V system load 50 operated by a 14V system battery and a 42V system load 52 operated by a 42V system battery are shown.

  The motor 56 is a vehicle drive source together with the engine 58, and is used as a start source for starting the engine 58. The PCU 54 is a circuit unit including an inverter circuit that performs conversion between DC power and a predetermined controlled AC drive signal.

  As described above, the load is roughly classified into the 14V system load 50 and the 42V system load 52. The former is configured to operate with a lead storage battery conventionally used as a power source for vehicles, for example, Auxiliary equipment such as air conditioners and wiper motors, and various electronic devices. The latter shall be equipment that requires relatively high power, and auxiliary equipment and electronic equipment that are newly added as hybrid vehicles evolve. Can do. For example, since oil pumps, igniters, and the like require a relatively large amount of electric power as hybrid vehicles evolve, it is preferable that they be assigned as 42V load 52 and operated by a 42V battery.

  The power supply system 10 of the hybrid vehicle includes a 200V high-voltage battery 12, a 14V battery 18, and a 42V battery 22 as batteries. In addition, the power supply system 10 of the hybrid vehicle includes a system main relay (SMR) 14 provided on each of the positive side bus and the negative side bus connecting the high voltage battery 12 and the PCU 54, the high voltage battery 12, and the 14V system battery 18. Is provided between the high voltage battery 12 and the 42V battery 22, and is a bidirectional 42V DC / DC capable of both stepping down and boosting. DC converter 20 is included. The temperature sensor 32 that detects the temperature of the engine 58 is also a component of the power supply system 10 of the hybrid vehicle.

  In addition to the two relays SMR-1 and SMR-2, the SMR 14 is shown as SMR-P in FIG. 1 and has a resistor connected in series to the relay. This is for slowly charging the power supply circuit system when the main relay is connected, and P in SMR-P represents precharge meaning pre-charge.

  The control unit 40 has a function of performing control related to the operation of the motor 56 of the vehicle. In particular, the control unit 40 has a function of performing start control when the motor 56 is used as a start source of the engine 58. The control unit 40 is connected to the temperature sensor 32, the SMR 14, the 42V DC / DC converter 20, and the PCU 54. Then, based on the detection result of the temperature sensor 32, the operation of the SMR 14 and the operation of the 42V DC / DC converter 20 are controlled, and the distribution of the electric power supplied to the PCU 54, the 42V battery 22 and the 42V load 52 is controlled. In that sense, a part of the function of the control unit 40 is a component of the power supply system 10 of the hybrid vehicle. The control unit 40 can be configured by a vehicle computer, and may be configured as a single element or may be configured in combination with the functions of other vehicle computers. For example, it can be configured as a part of a hybrid CPU that controls the entire hybrid vehicle.

  The high voltage battery 12 is an assembled battery configured by combining a plurality of unit cells such as lithium ion batteries or nickel metal hydride batteries. Since nickel-metal hydride cells have an output voltage of about 1.2V and lithium-ion cells have an output voltage of about 3.6V, the 200V high-voltage battery 12 combines about 200 cells in the former and about the latter in the latter. About 60 unit cells are combined. When the vehicle is in a regenerative operation, the high-voltage battery 12 can be charged by causing the motor 56 to act as a generator by the regenerative energy of the engine 58 and converting it into regenerative power by the PCU 54.

  The 42V system battery 22 can be configured by using the same unit cell as the high voltage battery 12 and having a different number of combinations. From another point of view, a 242V system battery of 200V + 42V = 242V can be configured, an intermediate tap is provided on the battery, and the 200V high voltage battery and the 42V system battery can be integrated. Of course, the high-voltage battery 12 and the 42V battery 22 can be configured as independent separate bodies using the same type of single cells. Further, in some cases, a 42V battery may be configured as a battery of a different type from the single battery configuring the high voltage battery 12. In addition, the 14V type | system | group battery 18 can use the lead storage battery conventionally used as a vehicle-mounted storage battery as mentioned above.

  The 14V DC / DC converter 16 is a DC voltage conversion circuit having a function of stepping down the high voltage power of the high voltage battery 12 to a 14V low voltage power. Thereby, the 14V battery 18 can be charged by the high voltage battery 12.

  The 42V DC / DC converter 20 has two voltage conversion functions. One of them is a function to step down the high voltage power of the high voltage battery 12 to a 42V low voltage power. As a result, the 42V battery 22 can be charged by the high voltage battery 12. The other is a DC voltage conversion circuit having a function of boosting low-voltage high-voltage power of a 42V battery to 200V high-voltage power. As a result, the 200V power can be increased by the power of the 42V battery 22. That is, the high voltage power is assisted by the power of the 42V battery 22.

  As described above, since the high voltage battery 12 and the 42V system battery 22 are composed of the same type of unit cell, it is likely that the high voltage battery 12 and the 42V system battery 22 have the same characteristics with only different terminal voltages. Since the latter is for loads such as auxiliary machines, the range of SOC (State of Charge) indicating the state of charge of the battery is different. This is shown in FIG. That is, in the high voltage battery 12 used for driving the vehicle, the SOC largely fluctuates due to fluctuations in the running state of the vehicle, and therefore the SOC range is widened. On the other hand, the 42V battery 22 used as a power source for auxiliary machines or the like is not subject to much fluctuations in the running state of the vehicle, and often continues to have a substantially constant power consumption and charging accordingly. Therefore, the SOC falls within a narrow range of relatively high values.

  As described above, the SOC of the 42V battery 22 falls within a narrow range of relatively high values. For example, if this is boosted and used, the output efficiency is higher than when the high-voltage battery 12 with large fluctuations in SOC is used. Can be high. That is, it is effective as a drive source for the motor 56, and is particularly effective when used as a power source with high output efficiency at a low temperature at which a decrease in battery output appears. The configuration of the power supply system 10 of the hybrid vehicle in FIG. 1, particularly the configuration of the control unit 40, has been made paying attention to the SOC characteristics of the 42V battery 22 described above, and improves the startability of the engine particularly at low temperatures. Can do.

  The control unit 40 includes an SMR connection processing module 42 that performs a process of connecting an SMR including a precharge when the vehicle is started, a temperature state determination module 44 that determines a temperature state related to the engine 58 based on a detection result of the temperature sensor 32, Auxiliary machine state determination module 46 that determines whether or not there is a load of an auxiliary machine or the like that requires operation at the time of starting, and a 42V system that commands the operation content of the 42V DC / DC converter 20 based on the temperature state and the auxiliary machine state And a DC / DC command module 48. The control unit 40 can be configured by a computer as described above, and these functions can be realized by software. Specifically, it can be realized by executing a corresponding start control program. Some of these functions may be realized by hardware.

  The operation of the power supply system 10 of the hybrid vehicle having the above configuration, particularly each function of the control unit 40 will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing an operation procedure of the power supply system 10 relating to the start of the hybrid vehicle, and each procedure corresponds to each processing procedure of the start control program. First, the ignition switch is turned on to start the vehicle (S10). When the control unit 40 acquires this state, the connection processing of the SMR 14 including precharge is performed by the function of the SMR connection processing module 42. For example, the SMR-2 is first connected, and after the elapse of a predetermined timing, the SMR-P is connected, and the power supply circuit system is gradually charged through the resistor. -1 is connected.

  Next, the detection data of the temperature sensor 32 is acquired by the function of the temperature state determination module 44, and it is determined whether or not the temperature state related to the engine 58 is a low temperature (S14). The temperature state related to the engine 58 can be determined by detecting the coolant temperature of the engine 58 with the temperature sensor 32 and comparing it with a predetermined standard, for example. The low temperature reference can be determined based on whether or not the output characteristics of the high-voltage battery 12 are reduced and there is a possibility that the start of the engine 58 by the motor 56 may be hindered in the step S42 described later. From this point of view, the temperature sensor 32 may detect the temperature of the high-voltage battery 12, the temperature inside the vehicle, the outside air temperature, or the like. The temperature related to the engine 58 broadly refers to these temperatures.

  If it is determined that the temperature state is low, corresponds to the start of the engine 58 at a low temperature, and the output characteristics of the high voltage battery 12 may be reduced, the process proceeds to S16, and the temperature state is not determined to be low, When the engine 58 does not fall under low temperature, the process proceeds to S40.

  In S <b> 16, it is determined by the function of the auxiliary machine state determination module 46 whether there is any 42V auxiliary machine or the like that operates at the time of starting. For example, when the igniter is used at the start and the igniter is assigned to the 42V system load 52, the result is affirmative in S16 and the process proceeds to S30. When all the auxiliary machines and electronic devices used at the start are assigned to the 12V system load 50, the determination in S16 is not affirmative and the process proceeds to S20. As described above, the auxiliary machine state indicates the load state of the auxiliary machine and the electronic device. When an auxiliary machine or the like that operates at the time of starting is fixed in advance, the determination in S16 is determined from the beginning, and the process is performed according to the determination. When the auxiliary machine that operates at the start changes depending on the situation, the operating state of the element that may change may be acquired by a detection means provided separately, and the auxiliary that actually operates at the start based on the acquired result. It is determined whether there is a machine or the like.

  If the determination in S16 is not affirmative, that is, if the load such as an auxiliary machine that operates at the start does not belong to the 42V system load, the operation is commanded so that the 42V system DC / DC converter 20 enters the boost mode (S20). ). This process is realized by the function of the 42V DC / DC command module 48 together with S30, S40, S24, and S34 described later.

  When the 42V DC / DC converter 20 is boosted, the power of the 42V battery 22 is converted into high voltage power, and the converted high voltage power is supplied to the PCU 54 together with the high voltage power from the high voltage battery 12. In other words, the high-voltage power supplied to the motor 56 is increased by the step-up operation of the 42V DC / DC converter 20. That is, the engine 58 is started by the motor 56 with the assistance of the high-voltage power from the 42V battery 20 (S22). As a result, the starting characteristics of the engine 58 are improved as compared with the case where the motor 56 is driven only by the high-voltage battery 12.

  After the engine 58 is started, an operation is commanded so that the 42V DC / DC converter 20 enters the step-down mode (S24). When the 42V DC / DC converter 20 is stepped down, the power of the high voltage battery 12 is converted into 42V low voltage power, and the 42V battery 22 is charged. As a result, the 42V system load 52 can operate upon receiving sufficient power supply, so READY-ON is performed (S26). READY-ON outputs a signal indicating that the startup process has been completed and the vehicle is ready for normal operation. Specifically, the ready lamp is lit in the passenger compartment. Thereafter, the driver can perform driving such as driving operation of the vehicle.

  If the determination in S16 is affirmative, that is, if there is a load such as an auxiliary machine that operates at the start belongs to a 42V system load, a command is issued to stop the operation of the 42V system DC / DC converter 20 ( S30). Stopping the operation of the 42V DC / DC converter 20 means that neither the step-up operation nor the step-down operation is performed. In other words, the relationship between the 42V DC / DC converter 20 and the high voltage battery 12 becomes disconnected, and the power of the high voltage battery 12 is supplied to the PCU 54 without being charged for charging the 42V system battery 22. Therefore, as compared with the case where the 42V DC / DC converter 20 is stepped down and the high voltage power of the high voltage battery 12 is divided, more high voltage power is supplied to the PCU 54, and the start characteristics of the engine 58 are improved accordingly. The At this time, the 42V system load 52 can be operated by the 42V system battery 22, and there is no problem in the operation of the entire vehicle. Since the contents of steps S34 and S36 after the engine 58 is started are the same as the contents of S24 and S26 described above, detailed description thereof will be omitted.

  As described above, if it is not determined in S14 that the temperature state is a low temperature, the process proceeds to S40. In S40, as in S24 and S34, the operation is commanded so that the 42V DC / DC converter 20 enters the step-down mode. As described above, when the 42V system DC / DC converter 20 is stepped down, the power of the high voltage battery 12 is converted into 42V system low voltage power, and the 42V system battery 22 is charged. At this time, high voltage power for starting the engine 58 is also supplied to the PCU 54. That is, when the temperature state is not low, the engine 58 is started while the high voltage power of the high voltage battery 12 is stepped down to 42V. Here, the high-voltage power of the high-voltage battery 12 is divided into power for starting the engine 58 and power for charging the 42V system battery 22, and the high-voltage power that is rotated for starting the engine 58 correspondingly. Will be less. However, the process of S40 is performed when the temperature state is not low, and the output characteristics of the high voltage battery 12 are sufficiently high, so that the high voltage power of the high voltage battery 12 is partly divided for charging the 42V system battery 22. However, the engine 58 can be sufficiently started. Since the contents of S44 after the engine is started are the same as S26 and S36, detailed description thereof is omitted.

  FIG. 4 is a diagram for explaining how high-voltage power is distributed in the three operation contents of the 42V DC / DC converter 20. 4A shows a case where the 42V DC / DC converter 20 is boosted, FIG. 4B shows a case where the operation of the 42V DC / DC converter 20 stops, and FIG. 4C shows a 42V DC / DC converter 20. Is the case where the pressure decreases.

  FIG. 4A shows a case of starting when the 42V system load 52 does not operate in a low temperature state. Here, as described in relation to S20 and S22, the high-voltage power supplied for starting the motor 56 is increased by the step-up operation of the 42V DC / DC converter 20. That is, the amount of high voltage power boosted from the 42V battery 22 is added to the high voltage power of the high voltage battery 12. As a result, the starting characteristics of the engine 58 are improved as compared with the case where the motor 56 is driven only by the high-voltage battery 12.

  FIG. 4B shows a case of starting when the 42V system load 52 operates in a low temperature state. Here, as described in relation to S30 and S32, the relation between the 42V DC / DC converter 20 and the high voltage battery 12 is cut off, and the power of the high voltage battery 12 is supplied to the PCU 54 by the 42V system. The battery 22 is supplied without being charged for charging. Therefore, as compared with the case where the 42V DC / DC converter 20 is stepped down and the high voltage power of the high voltage battery 12 is divided, more high voltage power is supplied to the PCU 54, and the start characteristics of the engine 58 are improved accordingly. The As described above, at this time, the 42V system load 52 can be operated by the 42V system battery 22, and there is no problem in the operation of the entire vehicle.

  FIG. 4C shows the case of starting when the temperature is not low, that is, when the output characteristics of the high-voltage battery 12 are not deteriorated. Here, as described in relation to S40 and S42, the 42V DC / DC converter 20 is stepped down, and the high voltage power of the high voltage battery 12 is stepped down to the power for starting the engine 58 and the 42V system. Power. Thus, even if the high-voltage power supplied for starting the engine 58 is reduced, the output characteristics of the high-voltage battery 12 are sufficiently high, so that the engine 58 can be sufficiently started.

  Thus, by providing the 42V system battery 22 and switching the operation of the 42V system DC / DC converter 20 according to the temperature related to the engine 58, it is possible to improve the low temperature startability of the vehicle and expand the capacity of the low voltage power source. It becomes.

It is a figure which shows the structure of the power supply system of the hybrid vehicle in embodiment which concerns on this invention. In embodiment which concerns on this invention, it is a figure explaining a mode that the range of SOC differs between a high voltage battery and a 42V type | system | group battery. In embodiment which concerns on this invention, it is a flowchart which shows the procedure of the action | operation of the power supply system in the start of a hybrid vehicle. In embodiment which concerns on this invention, it is a figure explaining the mode of distribution of the high voltage | pressure electric power in three operation | movement contents of the bidirectional | two-way 42V type DC / DC converter 20. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Power supply system of hybrid vehicle, 12 High voltage battery, 14 SMR, 16 14V system DC / DC converter, 18 14V system battery, 20 42V system DC / DC converter, 22 42V system battery, 32 Temperature sensor, 40 Control part, 42 SMR Connection processing module, 44 temperature state determination module, 46 auxiliary machine state determination module, 48 42V system DC / DC command module, 50 14V system load, 52 42 system load, 54 PCU, 56 motor, 58 engine.

Claims (5)

A high voltage battery;
A drive motor that starts the engine with electric power supplied from a high-voltage battery;
42V battery,
A load that operates with electric power supplied from a 42V battery;
A bidirectional 42V DC / DC converter provided between the high voltage battery and the 42V battery;
A temperature sensor for detecting the temperature related to the engine;
A control unit for controlling the operation of the 42V DC / DC converter according to the temperature detected by the temperature sensor;
A power supply system for a hybrid vehicle, comprising: In the hybrid vehicle power supply system according to claim 1,
The control unit
A hybrid vehicle characterized in that when the temperature detected by the temperature sensor is a low temperature equal to or lower than a predetermined temperature, the 42V DC / DC converter is boosted so that the electric power boosted from the 42V battery is supplied to the drive motor. Power system. The power supply system for a hybrid vehicle according to claim 2,
The control unit
A means for determining whether there is an auxiliary machine that needs to be operated at low temperatures;
A power supply system for a hybrid vehicle characterized in that when there is an auxiliary machine that needs to be operated at a low temperature, the control at a low temperature is not performed, but a stop control for stopping the operation of the 42V DC / DC converter is performed. The power supply system for a hybrid vehicle according to claim 1, further comprising:
A 14V battery,
A load that operates with electric power supplied from a 14V battery;
A 14V DC / DC converter provided between the high voltage battery and the 14V battery;
A power supply system for a hybrid vehicle, comprising: In the hybrid vehicle power supply system according to claim 1,
The 42V system battery is constituted by the same unit cell as the unit cell constituting the high voltage battery.

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