JP5863880B2 - In-vehicle DCDC converter - Google Patents

Description

  The present invention relates to an in-vehicle DCDC converter that is mounted on a vehicle having a low-voltage storage battery and a high-voltage storage battery having different operating voltages, and that controls power transfer between the low-voltage storage battery and the high-voltage storage battery.

  Conventionally, a vehicle is equipped with a plurality of control devices for performing power control and power control of the entire vehicle while managing the state of the storage battery. In addition, a state detection sensor such as an electrical state or a temperature state and a signal line are mounted on power supply system components including the storage battery.

  In such a configuration, when referring to the same sensor information among a plurality of control devices or when the function arrangement is not appropriate, sensor information is input via communication, or a similar function exists between control devices. Implementation has been done. For this reason, it cannot be said that efficient control is performed in the power transfer between the storage batteries carried by the DCDC converter.

  On the other hand, the method of providing the detection part of the various sensors which concern on the power transmission / reception between storage batteries inside a DCDC converter is proposed (for example, refer patent document 1). The DCDC converter of Patent Document 1 controls power transfer between the high voltage storage battery and the low voltage storage battery according to the detected state of the storage battery and the state of the electric load.

  On the other hand, with respect to the vehicle mounting position of the DCDC converter main body, a method of installing adjacent to the low voltage storage battery has been proposed for the purpose of reducing power loss and reducing the size of the periphery of the high voltage storage battery (see, for example, Patent Document 2). .

Japanese Patent No. 4259411 JP 2013-22991 A

However, the prior art has the following problems.
In patent document 1, the electric power transmission / reception between a high voltage storage battery and a low voltage storage battery is integrated by integrating the current detection part which detects the output value of the current sensor mounted in the low voltage storage battery, and converts it into a digital value in a DCDC converter. Is efficiently controlled.

  However, in Patent Document 1, a sensor signal line that connects a current sensor that measures the current of the storage battery and a current detection unit that digitally converts the output value of the current sensor exists outside the DCDC converter. For this reason, there has been a problem that the current detection accuracy is lowered due to the influence of noise received by the sensor signal line from the outside.

  Moreover, in patent document 2, a DCDC converter is installed adjacent to a low voltage storage battery, and the power loss is reduced by shortening a low voltage wiring. However, even with this method, the sensor signal line is still affected by noise, and the problem that the current detection accuracy is lowered as in the case of Patent Document 1 cannot be solved.

  Thus, in the in-vehicle DCDC converters of Patent Document 1 and Patent Document 2, the detection accuracy of the state of the low-voltage storage battery of the vehicle is reduced due to the influence of external noise. As a result, there has been a problem that the transfer of power between the high voltage storage battery and the low voltage storage battery cannot be effectively controlled according to the state of the charge rate of the low voltage storage battery. In addition, there is a problem that the cost of components increases when it is attempted to suppress the influence of external noise by providing a shield or the like to the sensor signal line.

  The present invention has been made to solve the above-described problems, and can suppress the influence of noise from the outside of the in-vehicle DCDC converter and detect the state of the low-voltage storage battery of the vehicle with high accuracy. It is an object of the present invention to obtain a low-cost in-vehicle DCDC converter capable of controlling power transfer between a low voltage storage battery and a high voltage storage battery according to the state of the voltage storage battery.

An in-vehicle DCDC converter according to the present invention is an in-vehicle DCDC converter that is mounted on a vehicle having a low-voltage storage battery and a high-voltage storage battery having different operating voltages, and controls the transfer of power between the low-voltage storage battery and the high-voltage storage battery. A current sensor that is installed adjacent to the low voltage storage battery, measures the current value of the low voltage storage battery, and outputs the current value as an analog current value via the sensor signal line; and the current value, voltage value of the low voltage storage battery, and Among the temperature state values, at least a state value including an analog current value output from the current sensor is input as an analog state value, and a state detection unit that converts the analog state value into a digital state value and outputs the digital state value, and a high voltage A state value including at least the current value among the current value, voltage value, and temperature state value of the storage battery is input as the second analog state value. With, based on the second analog state value and a second state detecting section for outputting a second digital state value and digital conversion, into a second digital state value of the digital state value and a high voltage battery of the low voltage battery A control arithmetic unit that controls transmission and reception of power between the low-voltage storage battery and the high-voltage storage battery, and the current sensor, the sensor signal line, and the state detection unit are integrated inside the in-vehicle DCDC converter. The control calculation unit calculates the charging rate of the low voltage storage battery based on the digital state value of the low voltage storage battery, and calculates the charging rate of the high voltage storage battery based on the second digital state value. Based on the charging rate of both the high voltage storage battery and the high voltage storage battery, the power supply is stepped down from the high voltage storage battery to the low voltage storage battery or the power increase from the low voltage storage battery to the high voltage storage battery is performed. Determining whether to perform the supply, and performs control of the power transfer.

  An in-vehicle DCDC converter according to the present invention includes a current sensor that measures a current value of a low-voltage battery of a vehicle, a current detection unit that digitally converts the measured current value, and a sensor signal line that connects the current sensor and the current detection unit. It is stored inside the module of the on-vehicle DCDC converter. As a result, it is possible to detect the state of the low voltage storage battery of the vehicle with high accuracy by suppressing the influence of noise from the outside of the in-vehicle DCDC converter, and between the low voltage storage battery and the high voltage storage battery according to the state of the low voltage storage battery. It is possible to obtain a low-cost in-vehicle DC / DC converter that can control power transmission / reception.

It is a schematic block diagram of the vehicle-mounted power supply system carrying the vehicle-mounted DCDC converter in Embodiment 1 of this invention. It is an illustration figure of the layout of the vehicle-mounted DCDC converter in Embodiment 1 of this invention. It is a flowchart which shows the conditions and procedure which transfer electric power between the high voltage storage battery and the low voltage storage battery in the key off in Embodiment 1 of this invention. It is a figure which shows the correction table of the determination value of a charging rate by the internal resistance of the low voltage storage battery in Embodiment 1 of this invention. It is a figure which shows the correction table of the determination value of a charging rate by the temperature of the low voltage storage battery in Embodiment 1 of this invention. It is a schematic block diagram of the vehicle-mounted power supply system carrying the vehicle-mounted DCDC converter in Embodiment 2 of this invention. It is a flowchart which shows the conditions and procedure which transfer electric power between the high voltage storage battery and the low voltage storage battery in Embodiment 2 of this invention during key-off. It is a figure which shows the correction table of the determination value of a charging rate by the internal resistance of the high voltage storage battery in Embodiment 2 of this invention. It is a figure which shows the correction table of the determination value of a charging rate by the temperature of the high voltage storage battery in Embodiment 2 of this invention.

  Hereinafter, preferred embodiments of an in-vehicle DCDC converter according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the part which is the same or it corresponds in each figure.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram of an in-vehicle power supply system equipped with an in-vehicle DCDC converter 1 according to Embodiment 1 of the present invention. The power supply system shown in FIG. 1 includes a high-voltage electrical load 101, a high-voltage storage battery 102 that supplies power to the high-voltage electrical load 101, a state detection device 103 for a secondary battery that detects the state of the high-voltage storage battery 102, and a low-voltage electrical A load 104, a low-voltage storage battery 105 that supplies power to the low-voltage electric load 104, a generator motor 106 provided with an internal combustion engine, and a DCDC converter 107 that transfers power between the high-voltage side and the low-voltage side are configured.

  Here, the secondary battery state detection device 103 includes a current detection unit 109 that detects a signal from a current sensor 108 that detects an input / output current of the high voltage storage battery 102, and a secondary battery state detection device 103. Voltage detector 110 detects a signal from a temperature sensor (not shown) installed in the vicinity of the voltage storage battery 102, and detects a signal from a voltage sensor (not shown) installed in the state detector 103 of the secondary battery. Unit 111 and calculation unit 112 that calculates the state of high-voltage storage battery 102 based on signals from three state detection units 109 to 111 (current detection unit 109, temperature detection unit 110, and voltage detection unit 111). It is prepared for.

  Further, the DCDC converter 107 detects a voltage drop at the main circuit unit 113 that transfers power between the high-voltage side and the low-voltage side, the shunt resistor (current sensor) 114 through which the input / output current of the low-voltage storage battery 105 flows, and the shunt resistor 114. Current detector 115 that performs amplification / AD conversion and the like, a temperature sensor (not shown), a temperature detector 116 that detects a signal from the temperature sensor, a voltage sensor (not shown), a voltage detector 117 that detects a signal from the voltage sensor, A calculation unit 118 that calculates the state of the low-voltage storage battery 105 based on signals received from the three state detection units 115 to 117 (current detection unit 115, temperature detection unit 116, and voltage detection unit 117), and A control unit 119 for controlling the main circuit unit 113 based on the signal and the signal received from the secondary battery state detection device 103 is provided. Composed of Te.

  In FIG. 1, the high voltage storage battery 102 is connected to the generator motor 106 so that power can be exchanged with the generator motor 106. The high voltage storage battery 102 is connected to the high voltage electrical load 101 so that power can be supplied to the high voltage electrical load 101. Further, the high voltage electrical load 101 and the generator motor 106 are connected in parallel to the high voltage storage battery 102.

  Further, the low voltage storage battery 105 is connected to the low voltage electric load 104 so that electric power can be supplied to the low voltage electric load 104.

  The DCDC converter 107 is connected to the low-voltage storage battery 105 and the high-voltage storage battery 102 so that power can be transferred between the high-voltage system including the high-voltage storage battery 102 and the low-voltage system including the low-voltage storage battery 105.

  The state detection units 109 to 111 of the secondary battery state detection device 103 and the calculation unit 112 are connected by a sensor signal line s 1, and the state detection units 109 to 111 output detection values to the calculation unit 112. doing. The calculation unit 112 inside the secondary battery state detection device 103 and the control unit 119 inside the DCDC converter 107 are connected by a signal line s2, and the calculation unit 112 relates to the state of the high voltage storage battery 102 to the control unit 119. The calculation result is output.

  In addition, the state detection units 115 to 117 and the calculation unit 118 of the DCDC converter 107 are connected by a sensor signal line s3, and the state detection units 115 to 117 output detection values to the calculation unit 118. . The calculation unit 118 and the control unit 119 inside the DCDC converter 107 are connected by a signal line s4, and the calculation unit 118 outputs a calculation result regarding the state of the low-voltage storage battery 105 to the control unit 119.

  The control unit 119 and the main circuit unit 113 are connected by a signal line s 5, and the control unit 119 outputs a control command to the main circuit unit 113.

  When the DCDC converter 107 supplies power from the high voltage side to the low voltage side by step-down, the output voltage to the low voltage side is determined based on a command from the control unit 119 based on the state of the low voltage storage battery 105. The main circuit unit 113 is controlled to be equal to or higher than the voltage value of the low voltage storage battery 105. Thus, power is supplied from the high voltage storage battery 102 to the low voltage electrical load 104 via the DCDC converter 107, and charging to the low voltage storage battery 105 is also performed simultaneously. As a result, it is possible to prevent the low voltage storage battery 105 from being overdischarged, and to prevent the deterioration of the low voltage storage battery 105 that shortens the life cycle due to overdischarge.

  Further, when the DCDC converter 107 boosts and supplies power from the low voltage side to the high voltage side, the output voltage to the high voltage side is determined based on a command from the control unit 119 based on the state of the low voltage storage battery 105. Is controlled to be equal to or higher than the voltage value of the high voltage storage battery 102. Thereby, the power supply from the low voltage storage battery 105 to the high voltage system electric load 101 is performed via the DCDC converter 107, and the high voltage storage battery 102 is also charged at the same time. As a result, a decrease in charge acceptance due to overcharging of the low voltage storage battery 105 can be suppressed.

  FIG. 2 is an exemplary diagram of a layout of the in-vehicle DCDC converter according to Embodiment 1 of the present invention. Although it is a well-known method, the low voltage storage battery 105 is assembled to the battery tray 204 with the battery holder 201, the bolt 202, and the bolt 203.

  The DCDC converter 107 is assembled to the battery tray 204 with bolts 205 and 206.

  Further, the positive terminal 207 of the low-voltage storage battery is connected to the low-voltage side positive terminal 208 of the DCDC converter 107 by a bus bar 209 with battery mounting terminals.

  Further, the high-voltage side positive terminal 210 of the DCDC converter 107 is connected to a positive terminal of a high-voltage storage battery (not shown), a high-voltage electric load, and a generator motor by a copper wire s11. The high-voltage side negative electrode terminal 211 of the DCDC converter 107 is connected to a vehicle body (not shown) by a copper wire s12. The signal terminal 212 is connected to a high-voltage secondary battery state detection device and a vehicle ECU (not shown) via a signal line s8.

  The shunt resistor 114 is disposed between the positive terminal portion 213 and the negative terminal portion 214 and is integrated through the DCDC converter 107. A resistor is disposed inside the DCDC converter 107, and the positive terminal portion 213 of the shunt resistor and the negative terminal portion 214 of the shunt resistor are exposed. Further, the negative terminal 215 of the low voltage storage battery is connected to the negative terminal portion 214 of the shunt resistor integrated with the DCDC converter 107 by a copper wire s9. The positive terminal portion 213 of the shunt resistor is connected to the vehicle body (not shown) by a copper wire s10.

  By laying out the in-vehicle DCDC converter as shown in FIG. 2, external wiring that causes noise between the shunt resistor 114 and the current detection unit 115 becomes unnecessary, so that current detection accuracy is improved. As a result, the low voltage storage battery 105 controls the supply of power in a specified life cycle by controlling the transfer of power based on the charging rate of the low voltage storage battery 105 so that the low voltage storage battery 105 does not overdischarge. Can be satisfied. Further, by integrating the shunt resistor 114 used conventionally in the module of the DCDC converter 107, the configuration of the first embodiment can be realized without an increase in cost due to a shield or the like.

  Here, if the low voltage storage battery 105 (for example, a lead storage battery) continues to be maintained in a state where the charging rate is low, the deterioration of the low voltage storage battery 105 due to sulfation or the like is rapid. Further, when the low voltage storage battery 105 is not charged due to leaving the vehicle for a long period of time or the like, the charging rate of the low voltage storage battery 105 decreases due to power consumption due to self-discharge or dark current, and the vehicle starts. It may be impossible.

  Therefore, in the first embodiment, the DCDC converter 107 further defines the conditions and procedure for power transfer during key-off in which power is not supplied to the low voltage storage battery 105. The power transfer conditions and procedures shown below are most effective when the vehicle is in key-off, but are not necessarily limited to during key-off, and are effective regardless of the driving state of the vehicle. I have it.

  FIG. 3 is a flowchart showing conditions and procedures for transferring power between high voltage storage battery 102 and low voltage storage battery 105 during key-off in DCDC converter 107 according to Embodiment 1 of the present invention. With reference to FIG. 3, the conditions and procedure of power transfer between the high voltage storage battery 102 and the low voltage storage battery 105 during key-off will be described.

  During key-off, in step s31, the calculation unit 118 includes at least the current value of the low voltage storage battery 105 output by the current detection unit 115 among the state values of the low voltage storage battery 105 output by the state detection units 115 to 117. Based on the above, the charging rate of the low voltage storage battery 105 (hereinafter referred to as “SOC1”) is calculated. Then, calculation unit 118 outputs the calculated SOC1 to control unit 119.

  Here, in order to suppress the deterioration of the performance of the low voltage storage battery 105 to ensure long-term reliability and to ensure sufficient charge power acceptability, the charging rate range of the low voltage storage battery 105 is limited. There is a need to.

  Therefore, in step s32, the control unit 119 determines whether or not SOC1 is less than 90% by setting, for example, a predetermined first threshold value that is a comparison target of the charging rate of the low voltage storage battery 105 to 90%. If SOC1 is less than 90%, control unit 119 determines that low voltage storage battery 105 is in an overdischarged state, and supplies the power from high voltage storage battery 102 to low voltage storage battery 105 in step s33. .

  Further, in step s34, the control unit 119 determines, for example, that the predetermined second threshold value to be compared with the charging rate of the low voltage storage battery 105 is 95%, and whether SOC1 is 95% or more. When SOC1 is 95% or more, control unit 119 determines that low voltage storage battery 105 is in an overcharged state, and boosts and supplies power from low voltage storage battery 105 to high voltage storage battery 102 in step s35.

  If the DCDC converter 107 does not have a step-up function and has only a step-down function, steps s34 and s35 do not exist.

  Further, when the first threshold value or the second threshold value of the charging rate is corrected based on the internal resistance of the low voltage storage battery and the charging rate becomes less than the corrected first threshold value, the high voltage storage battery reduces the low voltage. Electric power may be transferred to the storage battery. Alternatively, when the charging rate is equal to or higher than the corrected second threshold, power may be transferred from the low voltage storage battery to the high voltage storage battery. For example, when the internal resistance is large, the first threshold value of the charging rate is increased from 90% to 93%. Thereby, at the time of starting, the shortage of power supply to the starter can be solved and the engine can be started normally. By setting the SOC1 determination value in accordance with the internal resistance in this manner, the charging rate of the low-voltage storage battery can be controlled to be higher and the stable power can be supplied when the engine starts deteriorating. it can.

  The low-voltage storage battery that has deteriorated due to long-term use has increased internal resistance, so that the power supply to the starter becomes insufficient, and the engine may not start normally. Further, when the internal resistance increases, the voltage drop of the low voltage storage battery becomes large at the time of starting. If the voltage of the low-voltage storage battery is greatly reduced, the ignition device (not shown) and the vehicle control device (not shown) cannot be operated properly, and as a result, the engine may not be started normally. On the other hand, the lower the storage voltage of the low voltage storage battery, the lower the internal resistance.

  Therefore, in the present invention, a table for correcting the determination value of the charging rate based on the predetermined internal resistance of the low voltage storage battery shown in FIG. 4 is stored in a storage unit (not shown). Then, the SOC1 determination value is calculated based on the internal resistance of the low-voltage storage battery acquired during key-off and the above table.

  For example, when the low voltage storage battery has a predetermined charging rate and the internal resistance is IR1, the determination value of SOC1 is SOCth1, and the internal resistance increases due to deterioration or the like, and when the internal resistance becomes IR2, it is SOCth2. As described above, by setting the SOC1 determination value according to the internal resistance, when the engine starts, if the deterioration proceeds, the charging rate of the low voltage storage battery can be controlled to be high, and stable power can be supplied. Can do.

  When the low voltage storage battery is left in a low temperature environment for a long period of time, the internal resistance becomes high, so that the engine startability is deteriorated for the reason described above. On the other hand, the internal resistance of the low voltage storage battery decreases as the temperature increases.

  Therefore, in the present invention, a table for correcting the determination value of the charging rate based on the temperature of the low voltage storage battery specified in advance as shown in FIG. 5 is stored in a storage unit (not shown). Then, the SOC1 determination value is calculated based on the temperature of the low voltage storage battery acquired during key-off and the above table.

  For example, when the low-voltage storage battery has a predetermined charging rate and the temperature is T1, the SOC1 determination value is SOCth3. When the temperature is T2 due to being left in a low temperature environment for a long period of time, the SOCth4 is To do. Thus, by setting the SOC1 determination value according to the temperature of the low-voltage storage battery, stable power can be supplied even when the engine is started.

  As described above, according to the first embodiment, the sensor signal line that connects the current sensor and the current detection unit and is easily affected by external noise is stored or unnecessary in the DCDC converter for vehicle use. Therefore, the current detection accuracy is improved. Furthermore, in order to control the transfer of power based on the charging rate of the low voltage storage battery so that the low voltage storage battery does not overdischarge, the low voltage storage battery must satisfy the specified power supply in the specified life cycle. Can do. Further, the present invention can be realized without increasing the cost by integrating the current sensor used conventionally in the module of the DCDC converter.

  Furthermore, the DCDC converter can transfer power between the storage batteries based on the charging rate of the low voltage storage battery regardless of the driving state of the vehicle. As a result, the low voltage storage battery can always satisfy stable power supply including when the vehicle is started, and can effectively suppress deterioration of the low voltage storage battery.

  In addition, a table defining the relationship between the internal resistance value or temperature of the low voltage storage battery and the correction amount of the first threshold value or the second threshold value is stored in the storage unit, and based on the digital state value of the low voltage storage battery By acquiring the internal resistance value or temperature of the low-voltage storage battery and correcting the first threshold value or the second threshold value from the internal resistance value or temperature of the low-voltage storage battery according to the table, stable electric power can be obtained even when the engine is started. Can be supplied.

Embodiment 2. FIG.
In the first embodiment, a method is described in which the DCDC converter 107 controls transmission / reception of power based on the charging rate of the low voltage storage battery 105 so that the low voltage storage battery 105 does not enter an overdischarged state or an overcharged state. did. In the second embodiment, the DCDC converter 107 further controls the transmission / reception of power based on the charging rate of the high-voltage storage battery 102 so that the high-voltage storage battery 102 is not overcharged or discharged. explain.

  FIG. 6 is a schematic configuration diagram of an in-vehicle power supply system equipped with an in-vehicle DCDC converter according to Embodiment 2 of the present invention. The DCDC converter 401 shown in FIG. 6 further includes a current detection unit 402 that detects a signal from the current sensor 108 that detects the input / output current of the high-voltage storage battery 102 with respect to the DCDC converter 107 in the first embodiment. A temperature detection unit 403 that detects a signal from a temperature sensor (not shown), a voltage detection unit 404 that detects a signal from a voltage sensor (not shown), and each state detection unit 115-on the low voltage side instead of the calculation unit 118. 117 and an operation unit 405 for receiving signals from both the high-voltage side state detection units 402 to 404.

  The state detection units 402 to 404 and the calculation unit 405 of the DCDC converter 401 are connected by a signal line s 6, and the state detection units 402 to 404 output detection values to the calculation unit 405. The calculation unit 405 and the control unit 119 inside the DCDC converter 401 are connected by a signal line s7, and the calculation unit 405 sends the charge rate of the low voltage storage battery 105 and the charge rate of the high voltage storage battery 102 to the control unit 119. The calculation result is output.

  The portions other than those described above are the same as those in the first embodiment, and the same portions are denoted by the same reference numerals and description thereof is omitted.

  The DCDC converter 401 according to the second embodiment is configured so that the main circuit unit is based on a command from the control unit 119 when power is stepped down from the high voltage side to the low voltage side based on the state of the high voltage storage battery 102. In 113, the output voltage to the low voltage side is set to be equal to or higher than the voltage value of the low voltage storage battery 105. As a result, power is supplied from the high voltage storage battery 102 to the low voltage electrical load 104 via the DCDC converter 401, and at the same time, the low voltage storage battery 105 is charged.

  As a result, the DCDC converter 401 suppresses the overcharge state of the high voltage storage battery 102 by controlling power transfer based on the charge rate of the high voltage storage battery 102 so that the high voltage storage battery 102 is not overcharged. Thus, the progress of deterioration of the high voltage storage battery 102 can be suppressed, and heat generation and ignition can be prevented in advance. As a result, the high voltage storage battery 102 can satisfy the specified power supply in the specified life cycle.

  Here, when the high voltage storage battery 102 (for example, Li ion battery) is in an overdischarged state with a low charging rate, deterioration proceeds due to electrode dissolution. On the other hand, in an overcharged state where the charging rate is high, not only does the deterioration progress quickly, but it may cause heat generation and ignition.

  Therefore, in the second embodiment, the DCDC converter 401 further defines the conditions and procedure for power transfer during key-off. The power transfer conditions and procedures shown below are most effective when the vehicle is in key-off, but are not necessarily limited to during key-off, and are effective regardless of the driving state of the vehicle. I have it.

  FIG. 7 is a flowchart showing conditions and procedures for transferring power between high-voltage storage battery 102 and low-voltage storage battery 105 during key-off in DCDC converter 401 according to Embodiment 2 of the present invention. With reference to FIG. 7, the conditions and procedure of power transfer between high voltage storage battery 102 and low voltage storage battery 105 during key-off will be described.

  During key-off, in step s71, the calculation unit 405 includes at least the current value of the high voltage storage battery 102 output by the current detection unit 402 among the state values of the high voltage storage battery 102 output by the state detection units 402 to 404. Based on the above, the charging rate of the high voltage storage battery 102 (hereinafter referred to as SOC2) is calculated. Then, calculation unit 405 outputs calculated SOC2 to control unit 119.

  Here, in order to suppress the performance deterioration of the high-voltage storage battery 102 and ensure long-term reliability, it is necessary to limit the charge rate range of the high-voltage storage battery 102.

  Therefore, in step s72, control unit 119 determines whether or not SOC2 is 80% or more by setting, for example, a predetermined third threshold value to be compared with the charging rate of high voltage storage battery 102 to 80%. If SOC2 is 80% or more, control unit 119 determines that high voltage storage battery 102 is in an overcharged state, and supplies power from high voltage storage battery 102 to low voltage storage battery 105 in step s73. .

  In step s74, the control unit 119 determines whether or not the SOC2 is less than 20%, for example, by setting a predetermined fourth threshold value to be compared with the charging rate of the high voltage storage battery 102 to 20%. If SOC2 is less than 20%, control unit 119 determines that high-voltage storage battery 102 is in an overdischarged state, and boosts power from low-voltage storage battery 105 to high-voltage storage battery 102 in step s75. .

  If the DCDC converter 107 does not have a step-up function and has only a step-down function, steps s74 and s75 do not exist.

  Further, when the third threshold value or the fourth threshold value of the charging rate is corrected based on the internal resistance of the high voltage storage battery, and the charging rate becomes equal to or higher than the corrected third threshold value, the low voltage from the high voltage storage battery is reduced. Electric power may be transferred to the storage battery. Alternatively, when the charging rate is less than the corrected fourth threshold value, power may be transferred from the low voltage storage battery to the high voltage storage battery. For example, when the internal resistance is large, the fourth threshold value of the charging rate is increased from 20% to 23%. Thereby, when starting an engine with the electric power of a high voltage | pressure storage battery, the stable supply of required electric power is attained in engine starting.

  In the present invention, a table for correcting the determination value of the charging rate based on the predetermined internal resistance of the high voltage storage battery shown in FIG. 8 is stored in a storage unit (not shown). Then, the SOC2 determination value is calculated based on the internal resistance of the high-voltage storage battery acquired during key-off and the above table.

  For example, when the high voltage storage battery has a predetermined charging rate and the internal resistance is IR3, the SOC2 determination value is set to SOCth5. When the internal resistance increases due to deterioration or the like, and the internal resistance becomes IR4, it is set to SOCth6. In this way, by setting the SOC2 determination value according to the internal resistance, stable power can be supplied even when the engine is started.

  Further, when the high voltage storage battery is left in a low temperature environment for a long period of time, the internal resistance becomes high, so that the engine startability is deteriorated for the same reason as in the case of the above-described low voltage storage battery. On the other hand, the higher the temperature of the high voltage storage battery, the smaller the internal resistance.

  Therefore, in the present invention, a table for correcting the determination value of the charging rate based on the temperature of the predetermined high voltage storage battery as shown in FIG. 9 is stored in a storage unit (not shown). Then, the SOC2 determination value is calculated based on the temperature of the high-voltage storage battery acquired during key-off and the above table.

  For example, when the high voltage storage battery has a predetermined charging rate and the temperature is T3, the SOC2 determination value is SOCth7, and when the temperature is T4 due to being left in a low temperature environment for a long time, the SOCth8 To do. Thus, by setting the SOC2 determination value according to the temperature of the high-voltage storage battery, stable power can be supplied even when the engine is started.

  Although FIG. 7 shows a method for transferring power based on the charging rate of the high-voltage storage battery 102 during key-off, it goes without saying that charging of both the low-voltage storage battery 105 and the high-voltage storage battery 102 during key-off is performed. You may make it control based on a rate. In this case, since the charging rate of the low voltage storage battery 105 can be measured with high accuracy while suppressing external noise, the power of both storage batteries can be transferred and received more effectively.

  In addition, a table that defines the relationship between the voltage value of the high voltage storage battery and the current value of the low voltage storage battery so that the conversion efficiency of power transfer is optimal is stored in a storage unit (not shown), Based on the second digital state value of the voltage storage battery, the voltage of the high voltage storage battery is obtained, and the table shows the voltage value of the high voltage storage battery so that the conversion efficiency of power transfer is the optimum current value of the low voltage storage battery. Accordingly, it is possible to command the voltage value of the low voltage storage battery to the main circuit unit.

  As described above, according to the second embodiment, power transfer is controlled based on the charging rate of the high voltage storage battery so that the high voltage storage battery is not overcharged. As a result, the DCDC converter can suppress the progress of deterioration of the high-voltage storage battery and prevent heat generation and ignition, and the high-voltage storage battery satisfies the specified power supply in the specified life cycle. be able to.

  Furthermore, the DCDC converter can transfer power between the storage batteries based on the charging rate of the high-voltage storage battery regardless of the driving state of the vehicle. As a result, the high voltage storage battery can always be managed in an appropriate state, and deterioration of the high voltage storage battery can be effectively suppressed.

  In addition, this invention is not limited to the content of description of previous Embodiment 1 and this Embodiment 2, You may implement as changed as follows. In addition, the methods exemplified below may be arbitrarily combined.

  In the first embodiment and the second embodiment, the DCDC converter 107 is mounted with a shunt resistor in FIG. 2, but a non-contact current sensor may be mounted instead. In this case, a copper wire is wired through the DCDC converters 107 and 401 and the internal current sensor instead of the shunt resistor. Also in this method, the sensor signal line that connects the current sensor and the current detection unit and is easily affected by noise from the outside is stored or unnecessary in the on-board DCDC converter, so the current detection accuracy is improved. To do.

  In the first embodiment and the second embodiment, the wiring between the DCDC converters 107 and 401 and the low-voltage storage battery 105 is performed using a copper wire and a bus bar. The wiring may be changed to a bus bar.

  In the present invention, the high-voltage and low-voltage GNDs are shared as a non-insulating system, but the low-voltage side negative electrode may be separated from the body to provide an insulating system. In that case, in FIG. 2, the copper wire s12 is not connected to the body but directly connected to the negative electrode of a high voltage storage battery (not shown).

  In the first embodiment and the second embodiment, as shown in FIG. 2, it is described that the DCDC converters 107 and 401 can be assembled with bolts, but other assembling methods may be used.

  The present invention improves the current detection accuracy not only for the analog method but also for an external current sensor that employs a communication method such as LIN. For example, if communication is used, a loss of accuracy occurs due to a difference in clock frequency, communication delay, or the like. Also, the external wiring has more severe environmental conditions than the internal wiring. Furthermore, if a connector is provided, the failure rate increases by the amount of fitting. However, in the present invention, a sensor signal line that is easily affected by noise from the outside is stored or unnecessary in the in-vehicle DCDC converter, so that current detection accuracy is improved.

  In the first embodiment and the second embodiment, as shown in FIGS. 3 and 7, power is transferred based on the charging rate of the low-voltage storage battery 105 or the high-voltage storage battery 102 during key-off. However, it is not limited to this condition, and it may be controlled based on the charging rate of both storage batteries. For example, when SOC1 is less than 90% and SOC2 is 20% or more, power is transferred from the high voltage storage battery 102 to the low voltage storage battery 105. Moreover, regarding the charging rate, the determination value of SOC1 is 90% and the determination value of SOC2 is 20%, but is not limited to this value.

  Although it described as the temperature of a low voltage storage battery, it is good also as other temperature computed based on the temperature detection value of a DCDC converter. Needless to say, for example, a value obtained by correcting the temperature detection value of the DCDC converter may be used.

  In the first embodiment and the second embodiment, the lead storage battery and the Li ion battery are described as examples of the high voltage storage battery 102 and the low voltage storage battery 105, respectively, but the present invention is not limited thereto.

  In the second embodiment, power is transferred between the high voltage storage battery and the low voltage storage battery based on the charge rate of the high voltage storage battery. However, the charge rate of the high voltage storage battery is higher than a predetermined value, and the low voltage storage battery is fully charged. In the case of charging, power may be supplied to an electric load that is not perceived by the user in order to reduce the charging rate of the high voltage storage battery. Thereby, while suppressing the overcharge state of a high voltage storage battery, safety can be improved, and a high voltage storage battery can satisfy specified power supply in a specified life cycle.

  In the first embodiment and the second embodiment, the DCDC converters 107 and 401 may be either unidirectional DCDC converters or bidirectional DCDC converters. When the DCDC converters 107 and 401 have a boosting function, if the high voltage storage battery 102 falls into an overdischarged state, charging can be performed by connecting a general-purpose battery charger to the low voltage storage battery 105.

  DESCRIPTION OF SYMBOLS 101 High voltage system electric load, 102 High voltage storage battery, 103 Secondary battery state detection apparatus, 104 Low voltage system electric load, 105 Low voltage storage battery, 106 Generator motor, 107, 401 DCDC converter, 108 Current sensor, 109, 115, 402 Current detection unit, 110, 116, 403 Temperature detection unit, 111, 117, 404 Voltage detection unit, 112, 118, 405 Calculation unit, 113 Main circuit unit, 114 Shunt resistance (current sensor), 119 Control unit, 201 Battery holder 202, 203, 205, 206 Volts, 204 Battery tray, 207 Low voltage battery positive terminal, 208 Low voltage positive terminal, 209 Bus bar with battery mounting terminal, 210 High voltage positive terminal, 211 Negative terminal, 212 Signal terminal, 213 of shunt resistance Electrode side terminal portions 214 the negative terminal of the shunt resistor 215 low-voltage negative terminal of the storage battery, s1, s2, s3, s4, s5, s6, s7, s8 signal line, s9, s10, s11, s12 copper wire.

Claims (9)

An in-vehicle DCDC converter that is mounted on a vehicle having a low-voltage storage battery and a high-voltage storage battery having different operating voltages, and that controls power transfer between the low-voltage storage battery and the high-voltage storage battery,
A current sensor that is installed adjacent to the low voltage storage battery, measures the current value of the low voltage storage battery, and outputs an analog current value via a sensor signal line;
Of the current value, voltage value, and temperature state value of the low-voltage storage battery, at least a state value including the analog current value output by the current sensor is input as an analog state value, and the analog state value is converted into a digital value. And a state detector that outputs as a digital state value,
Among the current value, voltage value, and temperature state value of the high-voltage storage battery, a state value including at least the current value is input as a second analog state value, and the second analog state value is digitally converted. A second state detection unit that outputs as a second digital state value;
Based on the digital state value of the low-voltage storage battery and the second digital state value of the high-voltage storage battery, a control arithmetic unit that controls transmission and reception of power between the low-voltage storage battery and the high-voltage storage battery;
With
The current sensor, the sensor signal line, and the state detection unit are integrated inside the in-vehicle DCDC converter,
The control calculation unit is
While calculating the charging rate of the low voltage storage battery based on the digital state value of the low voltage storage battery, calculating the charging rate of the high voltage storage battery based on the second digital state value,
Based on the charging rate of the low-voltage storage battery and the charging rate of the high-voltage storage battery, perform a step-down supply of power from the high-voltage storage battery to the low-voltage storage battery, or from the low-voltage storage battery to the high-voltage storage battery An in- vehicle DCDC converter that determines whether or not to perform boosting supply of electric power and controls electric power transfer . When the charging rate of the high-voltage storage battery is higher than a predetermined value and the low-voltage storage battery is fully charged, the control calculation unit supplies power from the high-voltage storage battery to an electric load that is not sensed by the user.
The in-vehicle DCDC converter according to claim 1. The control calculation unit is
When the charging rate of the low voltage storage battery is less than a predetermined first threshold value and the charging rate of the high voltage storage battery is not less than a predetermined fourth threshold value, the low voltage is supplied from the high voltage storage battery. Step down power supply to storage battery,
When the charging rate of the low-voltage storage battery is equal to or higher than a predetermined second threshold and the charging rate of the high-voltage storage battery is not equal to or higher than a predetermined third threshold, the low voltage storage battery Boost the power supply to the storage battery,
When the charging rate of the high voltage storage battery is equal to or higher than the third threshold value and the charging rate of the low voltage storage battery is not equal to or higher than the second threshold value, electric power is supplied from the high voltage storage battery to the low voltage storage battery. Buck supply,
When the charging rate of the high voltage storage battery is less than the fourth threshold value and the charging rate of the low voltage storage battery is not less than the first threshold value, electric power is supplied from the low voltage storage battery to the high voltage storage battery. Boosted supply,
Here, the second threshold value is set as a value larger than the first threshold value, the fourth threshold value, according to claim 1 or 2 is set as the value smaller than the third threshold value DCDC converter for automotive use. Storing a first table defining a relationship between an internal resistance value of the low-voltage storage battery and a correction amount of the first threshold value or the second threshold value in a storage unit;
The control calculation unit calculates the internal resistance value of the low-voltage storage battery based on the digital state value of the low-voltage storage battery, and calculates the first resistance from the internal resistance value of the low-voltage storage battery according to the first table. The in-vehicle DCDC converter according to claim 3 , wherein the threshold value of 1 or the second threshold value is corrected. Storing a second table defining a relationship between a temperature value of the low-voltage storage battery and a correction amount of the first threshold value or the second threshold value in a storage unit;
The control calculation unit acquires the temperature of the low-voltage storage battery based on the digital state value of the low-voltage storage battery, and calculates the first threshold value or the temperature of the low-voltage storage battery according to the second table. The in-vehicle DCDC converter according to claim 3 or 4 , wherein the second threshold value is corrected. Storing a third table defining a relationship between an internal resistance value of the high-voltage storage battery and a correction amount of the third threshold value or the fourth threshold value in a storage unit;
The control calculation unit calculates the internal resistance value of the high voltage storage battery based on the second digital state value of the high voltage storage battery, and the internal resistance value of the high voltage storage battery according to the third table. The in-vehicle DCDC converter according to any one of claims 3 to 5, wherein the third threshold value or the fourth threshold value is corrected. Storing a fourth table defining a relationship between a temperature value of the high-voltage storage battery and a correction amount of the third threshold value or the fourth threshold value in a storage unit;
The control calculation unit acquires the temperature of the high-voltage storage battery based on the second digital state value of the high-voltage storage battery, and calculates the third voltage from the temperature of the high-voltage storage battery according to the fourth table. The in-vehicle DCDC converter according to any one of claims 3 to 6 , wherein the threshold value or the fourth threshold value is corrected. The current sensor is a shunt resistor penetrating through the inside of the in-vehicle DCDC converter, and has a positive terminal portion of the shunt resistor and a negative terminal portion of the shunt resistor outside the in-vehicle DCDC converter, negative terminal of the shunt resistor is connected to the negative terminal of the low voltage battery of the low voltage battery, the positive terminal of the shunt resistor is any one of claims 1 connected to the body of the vehicle 7 1 The in-vehicle DCDC converter according to the item. A fifth table that defines the relationship between the voltage value of the high-voltage storage battery and the current value of the low-voltage storage battery so that the conversion efficiency of the power transfer is optimal is stored in the storage unit,
The control calculation unit obtains the voltage of the high voltage storage battery based on the second digital state value of the high voltage storage battery, and is obtained from the voltage value of the high voltage storage battery according to the fifth table. The in-vehicle DCDC converter according to any one of claims 1 to 8 , wherein a voltage value of the low-voltage storage battery is controlled so as to be a current value of the low-voltage storage battery.

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