JP2015231301A - Power supply unit for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit for vehicle, capable of controlling a power supply voltage to be within a predetermined voltage range.SOLUTION: Voltage state detection means 111 includes charging rate detection means 111d for detecting the charging rate of a battery 110. A power supply management apparatus 108 includes charge and discharge threshold calculation means 108c for calculating charge and discharge threshold values based on a maximum operation voltage and a minimum operation voltage of the battery, and charge and discharge suppression means for suppressing charge and discharge of the battery when the charge rate of the battery reaches a charge threshold value and a discharge threshold value.

Description

  The present invention relates to a vehicle power supply device, and more particularly to a vehicle power supply device including means for controlling a power supply voltage within a predetermined voltage range.

  Vehicles are equipped with generators and secondary batteries to supply power to various electrical loads. Recently, due to demands for improving fuel efficiency, lithium secondary batteries have been developed as a power expansion measure for conventional lead battery systems. The adoption of batteries with high energy density, represented by ion batteries and electric double layer capacitors, is advancing. As for these batteries, in order to meet the voltage range and electric capacity required for the power source of the vehicle, a plurality of unit cells are generally connected in series as a set of battery modules (hereinafter referred to as assembled batteries). It is configured by combining assembled batteries in series or in parallel. In addition, a battery pack provided with a cell monitoring unit (hereinafter also simply referred to as CMU) that detects the state of each unit cell for each assembled battery in order to use all the unit cells safely. It is often handled in the form of The battery pack preferably includes fail-safe means for interrupting input / output based on the state of the battery detected by the CMU so that the internal battery is not damaged due to incorrect use.

  On the other hand, a means has been proposed in which a dedicated relay is provided between the assembled battery and the output terminal inside the battery pack, and the relay contact is opened when a battery abnormality is detected (see Patent Document 1). In this prior art, battery abnormality is detected by parameters such as voltage, current, temperature, state of charge (hereinafter also simply referred to as SOC), internal resistance, and the like. The purpose is protection.

JP2011-78147

  However, in the prior art disclosed in Patent Document 1, when the voltage of the battery inside the battery pack reaches an abnormal voltage, the relay contact can be opened. The voltage range required for the vehicle power supply cannot be controlled. That is, if a battery voltage abnormality is detected and the relay contact is opened, the battery pack stops output and the output terminal voltage becomes 0V.

  The present invention has been made to solve the conventional problems as described above. The battery pack output terminal voltage is kept within a predetermined voltage range without causing abnormal battery pack voltage due to overcharge or overdischarge. An object of the present invention is to provide a power supply device for a vehicle that can be controlled.

  A power supply device for a vehicle according to the present invention includes a battery that is charged by an electric generator of a vehicle and that supplies power to an electric load, battery state detection means that detects the state of the battery, and power management that performs power management based on the state of the battery. And a vehicle power supply device including a vehicle control unit that controls power generation and power consumption of the vehicle based on a command from the power management unit, and controls charging / discharging of the battery, wherein the battery state detection means Charging rate calculation means for detecting the charging rate of the battery, the power management unit calculates a charging threshold of the charging rate from the maximum operating voltage of the battery, and discharge threshold of the charging rate from the minimum operating voltage of the battery Charging / discharging threshold value calculating means, and charging / discharging suppressing means for suppressing charging / discharging of the battery when the charging rate of the battery reaches the charging threshold value or the discharging threshold value.

  According to the vehicle power supply device of the present invention, the SOC charge / discharge threshold is calculated from the maximum operating voltage and the minimum operating voltage of the battery pack, and the battery pack is controlled by controlling the charge / discharge current when the SOC reaches the charge / discharge threshold. Suppresses charging / discharging. As a result, the battery pack can control the output terminal voltage within a desired voltage range, that is, a voltage range required for the power source of the vehicle, without causing voltage abnormality due to overcharge or overdischarge.

  The above-described and other objects, features, and effects of the present invention will become more apparent from the detailed description and the drawings in the following embodiments.

It is a schematic block diagram of the whole vehicle power supply system including the vehicle power supply device in Embodiment 1 of this invention. It is a flowchart which shows the control processing of CMU inside a battery pack in Embodiment 1 of this invention. It is a flowchart which shows the control processing of the power management device in Embodiment 1 of this invention. It is a timing chart which shows the control action of the power supply device of the vehicle in Embodiment 1 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 shows a vehicle power supply apparatus according to Embodiment 1 of the present invention, and is a schematic configuration diagram of an entire vehicle power supply system including a power management unit, a vehicle control unit, and a high-voltage battery pack.
In FIG. 1, the high-voltage power supply system includes a battery pack 101, a motor generator 102 that is mechanically connected to an internal combustion engine (not shown) and generates or drives a vehicle, and a high-voltage electric load 103 of the vehicle. The low voltage power supply system includes a lead battery 104, a DCDC converter 105, a low voltage electric load 106 of the vehicle, a vehicle control device 107 as a vehicle control unit, and a power management device 108 as a power management unit. The Here, when the power management device 108 detects an abnormality of the battery pack 101, the power management device 108 opens the contact point of the fail-safe relay 109 inside the battery pack 101 and sends an emergency power supply command to the vehicle control device 107. Further, the vehicle control device 107 controls an internal combustion engine (not shown) and controls the motor generator 102, the high voltage electric load 103, and the low voltage electric load 106 in response to a command from the power management device 108.

  The battery pack 101 includes an assembled battery 110, a CMU 111 that detects the state of each unit cell inside the assembled battery 110, a fail-safe relay 109 that interrupts electrical connection with the outside when the battery pack 101 is abnormal, and a fail-safe relay 109. It is comprised from the control board 112 which controls the drive of this. Here, the CMU 111 detects the voltage, current, and temperature of each unit cell, and calculates the SOC and internal resistance of the battery based on these. A method for calculating these parameters will be described later with reference to FIG. In addition to the driving state of the fail safe relay 109, the control board 112 detects the temperature of the circuit unit inside the battery pack 101. The CMU 111 and the control board 112 transmit the internal state of the battery pack 101 detected to the power management apparatus 108, respectively.

  Based on the state inside the battery pack 101, the power management device 108 calculates the internal resistance of the entire battery pack 101, the SOC charge / discharge threshold, and the charge / discharge permission current. A method for calculating these parameters will be described later with reference to FIG. Further, the power management device 108 sends a command to the DCDC converter 105 and the vehicle control device 107 so that the charge / discharge current of the battery pack 101 falls within the charge / discharge permission current when the battery pack 101 is normal. The motor generator 102, the high voltage electric load 103, and the low voltage electric load 106 are controlled.

In addition, although the battery pack 101, the power supply management apparatus 108, the DCDC converter 105, the motor generator 102, and the vehicle control apparatus 107 are shown here individually, you may integrate each when mounting in a vehicle. When the functions of the power management device 108 serving as the power management unit are incorporated in the vehicle control device 107 and the devices are integrated, there are effects of cost reduction and weight reduction by the integration. On the other hand, when the power management device and the vehicle control device are provided separately, functions can be added without changing the original vehicle control device, and if there is an abnormality in the power management device, the original vehicle control device Only the vehicle can be operated.
Further, the power management device 108 shows a form of calculating the charge / discharge permission current as the charge / discharge suppression means, but instead of the charge / discharge permission current, the charge / discharge permission power of the battery pack 101, the output terminal target voltage, the operation of the motor generator 102 The vehicle control device 107 may control power generation and power consumption of the vehicle by transmitting any one of electric power, operating torque, and electric load discharge power to the vehicle control device 107.
Further, the motor generator 102 may be an alternator having only a power generation function. Moreover, although the form which provided CMU111, the control board 112, and the fail safe relay 109 separately about the internal structure of the battery pack 101 is shown, you may integrate each. Moreover, although a pair of form is shown about the assembled battery 110 and CMU111, you may provide two or more CMU111 according to the row | line | column number of a cell. In addition, the CMU 111 and the control board 112 make an abnormality determination based on the internal state of the battery pack 101 detected in each case, and in the case of an emergency, the contact of the fail safe relay 109 is opened regardless of the command of the power management device. Also good.

  FIG. 2 is a flowchart showing a control process of CMU 111 inside battery pack 101 according to Embodiment 1 of the present invention. In FIG. 2, in step 201, the voltage detection unit 111 a in FIG. 1 detects the voltage of each unit cell inside the assembled battery 110. In step 202, the current detection means 111b of FIG. 1 processes the signal of the current sensor CS provided between the assembled battery 110 and the negative electrode of the battery pack 101, whereby the current flowing through each unit cell inside the assembled battery 110 is obtained. To detect. In step 203, the temperature of each unit cell is detected by processing the signal of a thermistor (not shown) attached to the surface of each unit cell inside the assembled battery 110 by the temperature detection means 111c of FIG.

  In step 204, if the current detected in step 202 is approximately 0 (zero) A during a predetermined period, that is, if each unit cell is in a stationary state without charge / discharge, the voltage detected in step 201 at the end of the predetermined period. Considering the open circuit voltage (hereinafter also simply referred to as OCV), the SOC calculation of each cell is calculated by the charging rate calculation means 111d in FIG. 1 based on the OCV and the battery temperature detected in step 203. To do. In other states, the SOC of each unit cell is updated by integrating the current detected in step 202. In step 205, the internal resistance calculation unit 111e in FIG. 1 calculates a map of the internal resistance of each unit cell based on the SOC of each unit cell calculated in step 204 and the battery temperature detected in step 203. In step 206, the state of each single cell detected in steps 201 to 205 is transmitted to the power management apparatus 108. Note that the SOC and OCV for each battery temperature and the relationship between the SOC and the internal resistance for each battery temperature are battery characteristics determined by the manufacturer according to the degree of battery deterioration.

  FIG. 3 is a flowchart showing a control process of the power management apparatus 108 in the first embodiment of the present invention. In FIG. 3, in step 301, the state of each unit cell inside the battery pack 101 is received from the CMU 111. Regarding the battery state parameters to be referred to in the subsequent steps, the maximum value may be used during charging and the minimum value during discharging may be used in consideration of safety based on the average value of all single cells. In step 302, the temperature of the circuit unit inside the battery pack 101 is received from the pack internal temperature detection means 112 b of the control board 112. In step 303, the internal resistance of the battery calculated by the internal resistance calculation unit 111e of the CMU 111 by the pack internal resistance calculation unit 108b of FIG. 1 is calculated based on the temperature of the circuit unit inside the battery pack 101 detected in step 302. The internal resistance of the entire battery pack 101 is calculated by adding the electric resistances calculated in the table. In step 304, the battery pack abnormality detection means 108a in FIG. 1 determines whether the battery pack 101 is in an abnormal state based on the state of the battery pack 101 detected in steps 301 to 303. The relationship between the temperature of the circuit portion inside the battery pack 101 and the electrical resistance can be determined according to the temperature characteristics of the components of the current path excluding the battery between the positive and negative output terminals of the battery pack 101.

  If it is determined in step 304 that the battery pack 101 is abnormal, the process proceeds to step 305. In step 305, the relay control means 112a of the control board 112 in the battery pack 101 is instructed to open the contact of the failsafe relay 109. In the subsequent step 306, the charge / discharge permission current calculation means 108d, which is the charge / discharge suppression means in FIG. 1, is initialized to 0A by the charge / discharge permission current calculation means 108d. , The vehicle control device 107 shifts to the emergency power supply mode by the generator, and the vehicle control device 107 powers the internal combustion engine to continue power supply to the high voltage electric load 103 and the low voltage electric load 106. In response, the motor generator 102 is operated to generate electricity.

  If the abnormality of the battery pack 101 is not established in step 304, the process proceeds to step 308. In step 308, the charge / discharge permission current calculation means 108d in FIG. The smaller of the value and the output limit value of the motor generator 102 is divided by the battery voltage and set as the charge / discharge permission current A. The battery output limit value is a battery characteristic determined by the manufacturer based on the battery temperature as a limit value that does not damage the battery, and the output limit value of the motor generator 102 is determined from the influence of the power generation torque or the drive torque on the vehicle. Value. In step 309, the OCV charge / discharge threshold is calculated by subtracting the product of the charge / discharge permission current A calculated in step 308 and the internal resistance calculated in step 303 from the maximum operating voltage and the minimum operating voltage of the battery pack 101. . In step 310, the charge / discharge threshold value calculation means 108c calculates a map of the SOC charge / discharge threshold value from the OCV charge / discharge threshold value calculated in step 309 and the battery temperature. The relationship between the SOC and the OCV for each battery temperature is as described above. In step 311, it is determined whether the SOC of the battery received in step 301 is within the range of the SOC charge / discharge threshold calculated in step 310, that is, whether it is below the charge threshold and above the discharge threshold.

  If the SOC is not in the charge / discharge threshold range in step 311, the process proceeds to step 312, and the OCV is calculated from the SOC and battery temperature in the reverse order of step 310. In step 313, the charge / discharge permission current B of the battery pack 101 is calculated from the OCV calculated in step 312 and the internal resistance of the battery pack 101 calculated in step 303. That is, the value obtained by subtracting the OCV from the maximum operating voltage of the battery pack 101 and dividing by the internal resistance is the charge permission current, and the value obtained by subtracting the minimum operating voltage of the battery pack 101 from the OCV and dividing by the internal resistance is the discharge permission current. . In step 314, as the charge / discharge permission current when the SOC is not within the range of the charge / discharge threshold, the calculated value A in step 308 is compared with the calculated value B in step 313, and the smaller one is selected for each charge / discharge. To step 307.

If the SOC is within the charge / discharge threshold range in step 311, the process proceeds to step 307, and the charge / discharge permission current becomes the calculated value A in step 308. In step 307, the power management device 108 transmits the charge / discharge permission current selected in step 314 to the vehicle control device 107, so that the power management device 108 can maintain the charge / discharge current of the battery pack 101 within the charge / discharge permission current. The vehicle control device 107 controls the motor generator 102, the high voltage electric load 103, and the low voltage electric load 106 by the power generation control means 107a and the electrical equipment control means 107b.
That is, when step 311 is YES, the calculated value A of step 308 is vehicle control, and when step 311 is NO, the selected value of step 314 (minimum value of calculated value A and calculated value B) is used as the charge / discharge permission current. Transmitted to the device 107.

FIG. 4 is a timing chart showing the control operation of the power supply device for a vehicle in the first embodiment of the present invention, and corresponds to the control processing of steps 304 to 314 in FIG.
In FIG. 4, a solid line 401 indicates the output terminal voltage of the battery pack 101 in the present invention, a solid line 402 indicates the SOC of the battery pack 101 during charging, and a solid line 403 indicates the SOC of the battery pack 101 during discharging. Broken lines 404 and 405 indicate the output of the battery pack 101 when the power management apparatus 108 does not apply the control based on the SOC charge / discharge threshold, that is, when there is no control processing in steps 309 to 314 in FIG. The broken line 404 indicates the output terminal voltage during charging, and the broken line 405 indicates the output terminal voltage during discharging.

  Dotted lines 406 and 407 indicate threshold values for determining a voltage abnormality of the battery pack 101, and dotted lines 408 and 409 indicate the maximum operating voltage and the minimum operating voltage of the battery pack 101. Dotted lines 410 and 411 indicate the SOC charge / discharge threshold of the battery pack 101.

  The solid line 412 indicates the charging / discharging permission current of the battery pack 101 in the present invention, and the broken lines 413 and 414 indicate the case where the power management device 108 does not apply the control based on the SOC charging / discharging threshold as in the prior art, that is, FIG. The charging / discharging permission current of the battery pack 101 when there is no control processing of steps 309 to 314 is shown, the broken line 413 indicates the charging permission current, and the broken line 414 indicates the discharging permission current. In order to simplify the explanation, the charge / discharge current of the battery pack 101 during the period is controlled by the DCDC converter 105 and the vehicle control device 107 so as to match the charge / discharge permission current, and the temperature inside the battery pack 101 is constant. It shall be. Further, during the period in which the charging / discharging current of the battery pack 101 is 0 (zero) A, the vehicle control device 107 continues the power generation operation of the motor generator 102 to the high voltage electric load 103 and the low voltage electric load 106 of the vehicle. Power supply shall be performed.

At time t0, the SOC 402 and the output terminal voltage 401 of the battery pack 101 increase with charging. At time t1, the SOC 402 of the battery pack 101 exceeds the SOC charging threshold 410, so that the charge permission current is changed. At time t2, the output terminal voltage 401 of the battery pack 101 reaches the maximum operating voltage 408, and thereafter, the battery pack 101 is not charged until the voltage drops due to discharge. On the other hand, the output terminal voltage 404 when the control based on the SOC charge / discharge threshold is not applied is increased beyond the maximum operating voltage 408 because the charge permission current 413 is not changed, as in the conventional technique. Therefore, at time t3, the output terminal voltage 404 reaches the voltage abnormality threshold, the contact of the fail safe relay 109 is opened due to the battery pack abnormality being established, and the battery pack 101 stops outputting. After time t3, the charging / discharging current of the battery pack 101 becomes 0 A due to the power generation of the motor generator 102 described above. However, according to the present invention, the battery pack 101 is connected to the fail-safe relay contact, The pulsation of the power supply voltage can be suppressed and stabilized. That is, even if the fail-safe relay is on (connected) / off (released), the charge / discharge current is controlled to 0 (zero) A on average by the power generation of the motor generator. A fine ripple (pulsation) is superimposed on. Further, if there is a fluctuation in the electric load, the motor generator generates power to cancel the fluctuation, but there may be a delay with respect to the instantaneous fluctuation.
In contrast, when the fail-safe relay is in a connected state, a battery exists in the electric path between the motor generator and the electric load, and the battery becomes a smoothing element even when the ripple is superimposed or the electric load fluctuates. Power supply voltage can be stabilized.

After time t4, the battery pack 101 will be discharged. At time t4, the SOC 403 and the output terminal voltage 401 of the battery pack 101 decrease with discharge. At time t5, the SOC 403 of the battery pack 101 falls below the SOC discharge threshold 411, so that the discharge permission current is changed. At time t7, the output terminal voltage 401 of the battery pack 101 reaches the minimum operating voltage 409, and thereafter the battery pack 101 is not discharged until the voltage increases due to charging.
On the other hand, the output terminal voltage 405 in the case where the control based on the SOC charge / discharge threshold is not applied is not changed to the discharge permission current 414 after time t5, as in the conventional technique, and thus reaches the voltage abnormality threshold at time t6. When the battery pack abnormality is established, the contact of the fail safe relay 109 is opened, and the battery pack 101 stops outputting. The stabilization of the power supply voltage of the vehicle according to the present invention after time t7 is as described above.

As described above, according to the vehicle power supply device of the first embodiment of the present invention, the SOC charge / discharge threshold is calculated from the maximum operating voltage and the minimum operating voltage of the battery pack, and the SOC reaches this charge / discharge threshold. The charging / discharging of the battery pack is suppressed by controlling the charging / discharging current. Thereby, the battery pack 101 can control the output terminal voltage within a desired voltage range without causing voltage abnormality due to overcharge or overdischarge, and can operate within a predetermined voltage range required for the power source of the vehicle.
Also, when the battery pack 101 is abnormal, that is, when the battery pack is overcharged or overdischarged due to a short circuit inside the battery pack or erroneous detection of the SOC, the output of the battery pack 101 is stopped, and the motor generator By performing power generation operation of 102, it is possible to continuously supply power to the high-voltage electric load 103 and the low-voltage electric load 106 of the vehicle.

101 battery pack, 102 motor generator, 103 high voltage electric load,
104 lead battery, 105 DCDC converter, 106 low voltage electrical load,
107 vehicle control device, 107a power generation control means, 107b electrical equipment control means,
108 power management device, 108a battery pack abnormality detection means,
108b pack internal resistance calculation means, 108c charge / discharge SOC threshold value calculation means,
108d charge / discharge permission current calculation means, 109 fail-safe relay,
110 battery pack, 111 CMU, 111a voltage detection means,
111b current detection means, 111c temperature detection means, 111d charge rate calculation means,
111e internal resistance calculation means, 112 control board, 112a relay control means,
112b Pack internal temperature detection means.

The vehicle control apparatus according to the present invention includes a battery charged by a generator of the vehicle to supply power to an electric load, battery state detection means for detecting the state of the battery, and power management for performing power management based on the state of the battery. And a vehicle power supply device including a vehicle control unit that controls power generation and power consumption of the vehicle based on a command from the power management unit, and controls charging / discharging of the battery, wherein the battery state detection means Charging rate calculation means for detecting the charging rate of the battery, the power management unit calculates a charging threshold of the charging rate from the maximum operating voltage of the battery, and discharge threshold of the charging rate from the minimum operating voltage of the battery Charging / discharging threshold value calculating means for calculating the charging / discharging of the battery when the charging rate of the battery reaches the charging threshold value or the discharging threshold value, the vehicle control unit Charge / discharge permit Based on a command from the charging and discharging means for suppressing the power management unit for calculating a power, but with a power control unit and the electrical equipment control means for controlling the charging and discharging power of the battery.

Claims (6)

A battery that is charged by an electric generator of a vehicle and that supplies power to an electric load, a battery state detection unit that detects the state of the battery, a power management unit that performs power management based on the state of the battery, and a command from the power management unit A vehicle power supply device comprising a vehicle control unit for controlling power generation and power consumption of the vehicle based on the above, and controlling charging and discharging of the battery,
The battery state detection means includes a charge rate calculation means for detecting a charge rate of the battery,
The power management unit calculates a charging threshold of the charging rate from the maximum operating voltage of the battery, and a charging / discharging threshold value calculating means for calculating a discharging threshold of the charging rate from the minimum operating voltage of the battery;
A power supply device for a vehicle comprising: charge / discharge suppression means for suppressing charge / discharge of the battery when a charge rate of the battery reaches the charge threshold or the discharge threshold. The battery state detection means includes current detection means for detecting the current of the battery,
The vehicle control unit includes a power generation control unit and an electrical equipment control unit that control a charge / discharge current of the battery based on a command from a charge / discharge suppression unit of the power management unit that calculates a charge / discharge permission current of the battery. The power supply device for a vehicle according to claim 1.   The battery state detection means includes temperature detection means for detecting the temperature of the battery, and internal resistance calculation means for calculating the internal resistance of the battery from the temperature and charge rate of the battery, and the charge / discharge suppression means includes the The power supply device for a vehicle according to claim 2, wherein a charge / discharge permission current is calculated from a maximum operating voltage and a minimum operating voltage of the battery and the internal resistance. The battery state detection means includes voltage detection means for detecting the voltage of the battery,
The power management unit detects an abnormality of the battery when the voltage of the battery exceeds a maximum operating voltage and reaches a high voltage abnormality threshold or when the voltage of the battery falls below a minimum operating voltage and reaches a low voltage abnormality threshold. The power supply device for a vehicle according to any one of claims 1 to 3, further comprising battery abnormality detection means.   When the battery abnormality is detected based on a command from the battery abnormality detection unit, the battery control unit includes a battery output stop unit for stopping the output of the battery, and the vehicle control unit performs the power management when the battery output is stopped. The vehicle power supply device according to claim 4, wherein the generator is driven based on a command from a section to perform emergency power feeding to the electric load.   The vehicle power supply device according to any one of claims 1 to 5, wherein the power supply management unit and the vehicle control unit are integrated into a vehicle control device.