JP2020183161A - Power supply unit and power supply system - Google Patents

Abstract

To provide a power supply unit and a power supply system that can properly calculate internal resistance of a second storage battery without having influence on behaviour of a vehicle.SOLUTION: A power supply unit 40 is applied to a power supply system 100 that is mounted on a vehicle in which an engine 30 is automatically stopped and restarted according to a prescribed condition and is equipped with a first storage battery 11 that is used for power supply at the time of initially starting the engine and a second storage battery 12 that is used for power supply at the time of restarting the engine after the engine is automatically stopped, which are connected in parallel to a rotating electric machine 10, which comprises: a driving control part that brings the rotating electric machine into a force driving state by power supply from the second storage battery, under a low-efficiency state where efficiency of the rotating electric machine is equal to a predetermined value or less, after initially starting the engine 30; and a resistance calculation part that calculates internal resistance of the second storage battery, when the driving control part brings the rotating electric machine into the force driving state under the low efficiency state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply system mounted on a vehicle and a power supply device applied to the power supply system.

As a power supply system mounted on a vehicle, a configuration in which two batteries, a first storage battery (sub-battery) and a second storage battery (main battery), are mounted as a power source is known. These two storage batteries are connected in parallel via a relay, a starter and a motor generator are connected to the second storage battery, and various electric loads that do not allow a voltage drop are connected to the first storage battery.

In addition, for the purpose of improving fuel efficiency and reducing gas emissions, idling stop control is performed to automatically stop the engine when a predetermined automatic stop condition is satisfied and then restart the engine when a predetermined restart condition is satisfied. The power system to do is known. In this power supply system, when the engine is started for the first time, the electric power of the first storage battery is used to drive the motor generator, and when the engine is restarted, the electric power of the second storage battery is used to drive the motor generator. ..

In the technique described in Patent Document 1, a power supply system for calculating the internal resistance of the second storage battery after the initial start by the first storage battery is disclosed for the purpose of avoiding the failure of restarting the engine. In this power supply system, the internal resistance of the second storage battery is calculated in a state where a current equal to or higher than a predetermined value is applied to the second storage battery, for example, at the start of power assist, and the condition is that the internal resistance is less than a predetermined threshold value. The engine is allowed to restart by supplying power from the second storage battery. This prevents the engine from being restarted properly.

JP-A-2017-25709

Unless the current energized in the second storage battery is large, the internal resistance of the second storage battery at the time of restart cannot be calculated appropriately. For example, since the current flowing during power assist is smaller than the current flowing during restart, there is a problem that the internal resistance of the second storage battery at restart cannot be calculated appropriately using the current flowing during power assist. On the other hand, if the current flowing during power assist is increased to the same level as the current flowing during restart in order to calculate the internal resistance of the second storage battery at restart, the power applied to the vehicle becomes excessive, which affects the vehicle behavior. There was a problem to affect.

The present invention has been made in view of the above, and an object of the present invention is to provide a power supply device and a power supply system capable of appropriately calculating the internal resistance of the second storage battery without affecting the vehicle behavior.

The first means for solving the above problems is mounted on a vehicle that automatically stops and restarts the engine according to a predetermined condition, is connected in parallel to the rotary electric machine, and supplies electric power at the first start of the engine. A power supply device applied to a power supply system including a first storage battery used for the engine and a second storage battery used for supplying electric power at the time of restarting the engine after the automatic stop of the engine. After starting, under a low efficiency state in which the efficiency of the rotary electric machine is equal to or less than a predetermined value, a drive control unit that puts the rotary electric machine into a power running state by supplying electric power from the second storage battery, and the drive control unit that lowers the efficiency. It is provided with a resistance calculation unit that calculates the internal resistance of the second storage battery when the rotary electric machine is put into a power running state under an efficiency state.

In a vehicle having an idling stop function, after the initial start using the electric power of the first storage battery, the restart using the electric power of the second storage battery is appropriately performed. In this case, it is desirable that the engine is automatically stopped after grasping the state such as deterioration of the second storage battery. In this regard, in the above configuration, the internal resistance of the second storage battery is calculated when the rotary electric machine is driven by power by supplying power from the second storage battery in a low efficiency state where the efficiency of the rotary electric machine is equal to or less than a predetermined value. I made it. The "power running drive state" includes a state in which the armature winding of the rotary electric machine is energized so as to perform a power running operation, and a state in which the power running operation is not generated.

By putting the rotary electric machine in the power running state under the low efficiency state, the second storage battery can be used in a state where the power to the vehicle is not increased as compared with the case where the rotary electric machine is put into the power running drive state under the condition not in the low efficiency state. The flowing current can be increased. That is, for example, even at the time of power assist, the current flowing through the second storage battery can be increased to the same level as at the time of restart while suppressing the increase in the power of the vehicle. As a result, the internal resistance of the second storage battery can be calculated appropriately without affecting the vehicle drive.

In the second means, the rotary electric machine performs power assist when a predetermined assist condition is satisfied while the vehicle is traveling, and the drive control unit performs the power assist when the assist condition is not satisfied. Under the low efficiency state, the rotary electric machine is put into a power running state.

The rotary electric machine performs power assist when a predetermined assist condition is satisfied, and does not perform power assist when the assist condition is not satisfied. According to the above configuration, during the rest period of the rotary electric machine that does not perform the power assist, the rotary electric machine is put into the power running state in the low efficiency state, and the internal resistance of the second storage battery is calculated. As a result, the internal resistance of the second storage battery can be appropriately calculated by effectively utilizing the rotary electric machine during the suspension period.

In the third means, when the engine speed is higher than the predetermined speed, the drive control unit puts the rotary electric machine into the power running drive state as being in the low efficiency state.

When the engine speed is larger than the predetermined speed, the amount of increase in the engine speed due to power application to the vehicle is suppressed as compared with the case where the engine speed is smaller than the predetermined speed. That is, the efficiency of the rotary electric machine becomes a predetermined value or less, which is a low efficiency state. Therefore, by calculating the internal resistance of the second storage battery when the engine speed is larger than the predetermined speed, the internal resistance of the second storage battery can be appropriately calculated without affecting the vehicle drive.

In the fourth means, when the temperature of the rotary electric machine is higher than a predetermined temperature, the drive control unit puts the rotary electric machine into a power running drive state as being in the low efficiency state.

When the temperature of the rotary electric machine is higher than the predetermined temperature, the heat loss in the rotary electric machine suppresses the increase in the engine speed due to the power application to the vehicle as compared with the case where the temperature is lower than the predetermined temperature. That is, the efficiency of the rotary electric machine becomes a predetermined value or less, which is a low efficiency state. Therefore, by calculating the internal resistance of the second storage battery when the temperature of the rotary electric machine is higher than the predetermined temperature, the internal resistance of the second storage battery can be appropriately calculated without affecting the vehicle drive.

In the fifth means, the drive control unit puts the rotary electric machine into a power running state with a current flowing only in the d-axis of the d-axis and the q-axis of the rotary electric machine.

When the current flows only on the d-axis of the rotary electric machine, no torque is generated in the rotary electric machine, so that the amount of increase in the engine speed is suppressed. That is, the efficiency of the rotary electric machine becomes a predetermined value or less, which is a low efficiency state. Therefore, by calculating the internal resistance of the second storage battery in a state where the current flows only on the d-axis of the rotary electric machine, the internal resistance of the second storage battery can be appropriately calculated without affecting the vehicle drive.

The sixth means includes a restart determination unit that determines whether or not to permit the restart by supplying power from the second storage battery based on the internal resistance calculated by the resistance calculation unit.

According to the above configuration, the idling stop control can be appropriately performed after grasping the state such as deterioration of the second storage battery.

The seventh means is a power supply system mounted on a vehicle that automatically stops and restarts the engine according to a predetermined condition, and is connected in parallel to the rotary electric machine and the rotary electric machine to start the engine for the first time. The efficiency of the rotary electric machine after the first storage battery used for power supply at the time, the second storage battery used for power supply at the time of restarting after the automatic stop of the engine, and the first start of the engine. A drive control unit that puts the rotary electric machine into a power driving state by supplying electric power from the second storage battery under a low efficiency state of a predetermined value or less, and a drive control unit that drives the rotary electric machine by power running under the low efficiency state. A resistance calculation unit for calculating the internal resistance of the second storage battery when the state is set is provided.

In the above configuration, the internal resistance of the second storage battery is calculated when the rotary electric machine is put into a power running state by supplying electric power from the second storage battery in a low efficiency state where the efficiency of the rotary electric machine is equal to or less than a predetermined value. As a result, the current flowing through the second storage battery can be increased while the power to the vehicle is not increased, and the internal resistance of the second storage battery can be appropriately calculated without affecting the vehicle drive.

Schematic block diagram of the power supply system. The flowchart which shows the procedure of the control process which concerns on 1st Embodiment. A time chart showing an example of control processing. The figure which shows the relationship between the difference current and the difference voltage. The figure which shows the relationship between the rotation speed of a rotary electric machine and the torque of a rotary electric machine. The flowchart which shows the procedure of the control process which concerns on 2nd Embodiment. The figure which shows the relationship between the temperature of a rotary electric machine and the heat loss of a rotary electric machine. The flowchart which shows the procedure of the control process which concerns on 3rd Embodiment.

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. The vehicle equipped with the power supply system 100 of the present embodiment travels by using the engine 30 as a drive source, and has a so-called idling stop function.

(First Embodiment)
As shown in FIG. 1, the power supply system 100 includes a rotary electric machine 10, a lead storage battery 11, a lithium ion storage battery 12, a starter 13, an electric load 14, a current detection unit 15, a voltage detection unit 16, a first switch 21, and a second switch. 22 and a third switch 23 are provided. Of these, the lithium ion storage battery 12, the first switch 21, and the second switch 22 are integrated by being housed in a housing (storage case) (not shown), and are configured as a battery unit U. In the present embodiment, the lead storage battery 11 corresponds to the "first storage battery", and the lithium ion storage battery 12 corresponds to the "second storage battery".

The battery unit U is provided with a first terminal T1 and a second terminal T2 as external terminals. The lead storage battery 11 and the electric load 14 are connected to the first terminal T1, and the rotary electric machine 10 and the starter 13 are connected to the second terminal T2. Both the terminals T1 and T2 are large-current input / output terminals through which the input / output current of the rotary electric machine 10 flows.

The rotary shaft of the rotary electric machine 10 is driven and connected to an engine output shaft (not shown) by a belt or the like. Rotates the engine output shaft. In this case, the rotary electric machine 10 has a power generation function of generating power (regenerative power generation) by rotating the engine output shaft and the axle, and a power running function of applying power to the engine output shaft. For the rotary electric machine 10, for example, an ISG (Integrated Starter Generator) is used.

The lead storage battery 11 and the lithium ion storage battery 12 are electrically connected to the rotary electric machine 10 in parallel, and the storage batteries 11 and 12 can be charged by the generated power of the rotary electric machine 10. Further, the rotary electric machine 10 applies power (power running operation) to the engine 30 by supplying power from the storage batteries 11 and 12.

The lead storage battery 11 is a well-known general-purpose storage battery. For example, lead dioxide (PbO2) is used as the positive electrode active material of the lead storage battery 11, and lead (Pb) is used as the negative electrode active material. Further, sulfuric acid (H2SO4) is used as the electrolytic solution. Then, the lead storage battery 11 is configured by connecting a plurality of battery cells composed of these electrodes in series. In this embodiment, the storage capacity of the lead storage battery 11 is set to be larger than the storage capacity of the lithium ion storage battery 12.

Compared with the lead-acid battery 11, the lithium-ion storage battery 12 has a smaller internal resistance RL in an unused state (new), a smaller power loss during charging / discharging, and a higher output density and energy density (high power acceptability). ) It is a high-density storage battery.

For example, an oxide containing lithium (lithium metal composite oxide) is used as the positive electrode active material of the lithium ion storage battery 12. Specific examples include LiCoO2, LiMn2O4, LiNiO2, LiFePO4 and the like. As the negative electrode active material of the lithium ion storage battery 12, an alloy containing carbon (C), graphite, lithium titanate (for example, LixTiO2), Si or Su is used. An organic electrolytic solution is used as the electrolytic solution of the lithium ion storage battery 12. Then, the lithium ion storage battery 12 is configured by connecting a plurality of battery cells composed of these electrodes in series.

Reference numerals 11a and 12a in FIG. 1 represent battery cell assemblies of the lead-acid battery 11 and the lithium-ion storage battery 12, and reference numerals 11b and 12b represent the internal resistances of the lead-acid battery 11 and the lithium-ion storage battery 12. Further, in the following description, the open circuit voltage V0 of the storage battery is a voltage generated by the battery cell aggregates 11a and 12a.

The battery unit U is provided with a first connection path L1 and a second connection path L2 for connecting the terminals T1 and T2 and the lithium ion storage battery 12 to each other as an electric path in the unit. A first switch 21 is provided in the first connection path L1 that connects the first terminal T1 and the second terminal T2, and the connection point N1 (battery connection point) on the first connection path L1 and the lithium ion. A second switch 22 is provided in the second connection path L2 that connects the storage battery 12.

For example, semiconductor switches such as P-channel MOSFETs and N-channel MOSFETs are used for the first switch 21 and the second switch 22.

Further, the power supply system 100 is provided with a bypass path L3 that enables the lead storage battery 11 and the rotary electric machine 10 to be connected without going through the first switch 21. The bypass path L3 bypasses the battery unit U and is an electric path connected to the first terminal T1 (a path connected to the lead storage battery 11 or the like) and an electric path connected to the second terminal T2 (rotary electric machine 10). It is provided so as to electrically connect to the path) connected to.

A third switch 23 is provided on the bypass path L3 to cut off or conduct a connection between the lead-acid battery 11 side and the rotary electric machine 10 side. For the third switch 23, for example, a normally closed relay switch is used. It is also possible to provide the bypass path L3 and the third switch 23 so as to bypass the first switch 21 in the battery unit U.

The starter 13 is a starting device for starting the engine 30. When the ignition switch of the vehicle (not shown) is turned on and the starter 13 is turned on, the engine 30 is started by the electric power supplied from the lead storage battery 11.

The electric load 14 has a constant voltage required load that requires the voltage of the supplied power to be substantially constant, or at least stable so as to fluctuate within a predetermined range, and a general load other than the constant voltage load. ..

Explaining the electric load 14 in detail, the constant voltage required load includes a traveling load related to vehicle traveling and a non-traveling load. Examples of the traveling load include a braking device, an oil pump for an automatic transmission, a fuel pump, an electric power steering, and the like. Examples of loads other than those for traveling include navigation devices, display devices that display meters and the like, audio devices, and the like. The general load has a relatively wide operating voltage range compared to the constant voltage required load, such as headlights, wipers such as front windshields, blower fans for air conditioners, and heaters for defrosters on rear windshields. Can be mentioned.

The current detection unit 15 is connected in series to the lithium ion storage battery 12 and detects the charge / discharge current IL flowing through the lithium ion storage battery 12. The voltage detection unit 16 is connected in parallel to the lithium ion storage battery 12 and detects the voltage VL between terminals applied to the lithium ion storage battery 12.

The rotary electric machine 10 performs a power running operation that applies power to the engine output shaft. For example, when a predetermined assist condition is satisfied while the vehicle is running, power is applied to the engine output shaft to perform power assist. Here, the assist condition is, for example, a condition during acceleration in a low speed state of the vehicle. In addition, power is applied to the engine output shaft when restarting from automatic stop by idling stop control.

The rotary electric machine 10 is in a state in which power is not applied to the engine 30 by the drive of the rotary electric machine 10 when the vehicle is constantly running or automatically stopped. Further, when the vehicle accelerates, or when the engine 30 is restarted after the automatic stop, the power is applied to the engine 30 by driving the rotary electric machine 10.

Further, the rotary electric machine 10 also serves as a generator that generates electricity by the rotational energy of the engine output shaft. For example, when the rotor is rotated by the engine output shaft in the rotary electric machine 10, an alternating current is induced in the stator coil according to the exciting current flowing through the rotor coil, and is converted into a direct current by a rectifier (not shown). Then, the exciting current flowing through the rotor coil in the rotary electric machine 10 is adjusted by the regulator so that the voltage of the generated DC current becomes a predetermined voltage.

The electric power generated by the rotary electric machine 10 is supplied to the electric load 14, and is also supplied to the lead storage battery 11 and the lithium ion storage battery 12. When the driving of the engine 30 is stopped and the rotary electric machine 10 is not generating electric power, electric power is supplied from the lead storage battery 11 and the lithium ion storage battery 12 to the electric load 14. The amount of discharge from the lead-acid battery 11 and the lithium-ion storage battery 12 to the electric load 14 and the amount of charge from the rotary electric machine 10 are appropriately adjusted so that the SOC (State of charge) does not become overcharged / discharged. There is.

The engine 30 is provided with a rotation detection unit 17. The rotation detection unit 17 detects the engine speed NE, which is the number of revolutions of the engine 30 per unit time. Further, the rotary electric machine 10 is provided with a temperature detection unit 18. The temperature detection unit 18 detects the temperature YM of the rotary electric machine 10.

The control unit 40 carries out various processes in the power supply system 100. For example, the control unit 40 drives the starter 13 to drive the engine 30 when it determines that there is an initial start request based on the signal from the ignition switch. In this embodiment, the control unit 40 corresponds to the "power supply device". At this time, the starter 13 is driven by the power supply from the lead storage battery 11.

In addition, the control unit 40 performs idling stop control. In the idling stop control, as is well known, the engine 30 is automatically stopped when a predetermined automatic stop condition is satisfied, and the engine 30 is restarted when a predetermined restart condition is satisfied under the automatic stop state. When restarting the engine 30 that is automatically stopped, the control unit 40 supplies power from the lithium ion storage battery 12 with the first switch 21 turned off and the second switch 22 turned on. Drive the rotary electric machine 10.

As described above, in the power supply system 100 having two power sources of the lead storage battery 11 and the lithium ion storage battery 12, when the engine 30 is started for the first time, a stable voltage can be output against a large current discharge at the time of the first start. The lead storage battery 11 is used. On the other hand, when the engine 30 is restarted from the stopped state of the engine 30 by idling stop control, the lithium ion storage battery 12 having good charge / discharge characteristics is used. As a result, the automatic restart of the engine 30 is preferably performed by using the lithium ion storage battery 12 having good charge / discharge characteristics while suppressing early deterioration of the lead storage battery 11 having low durability against frequent charge / discharge (cumulative charge / discharge). Can be carried out.

By the way, if the lithium ion storage battery 12 is in a deteriorated state, the power of the lithium ion storage battery 12 may be insufficient. If the engine 30 is automatically stopped in this deteriorated state, there is a concern that the restart of the engine 30 by the rotary electric machine 10 implemented by using the lithium ion storage battery 12 as a power source will be hindered.

Therefore, it is preferable to calculate the internal resistance RL as the deteriorated state of the lithium ion storage battery 12 after the engine 30 is started for the first time. The internal resistance RL can be calculated using, for example, the inter-terminal voltage VL detected by the voltage detection unit 16 and the charge / discharge current IL detected by the current detection unit 15.

When calculating the internal resistance RL after the initial start of the engine 30, for example, power assist is performed by driving the rotary electric machine 10 as the vehicle accelerates, and the lithium ion storage battery 12 is energized by the current (discharge current) flowing at that time. To do. Then, for example, at the start of power assist, the deterioration state of the lithium ion storage battery 12 can be confirmed by calculating the internal resistance RL of the lithium ion storage battery 12 in a state where a predetermined current or more is applied to the lithium ion storage battery 12. Conceivable.

However, since the current flowing during power assist is smaller than the current flowing during restart, the internal resistance RL of the lithium ion storage battery 12 at restart cannot be properly calculated using the current flowing during power assist. On the other hand, if the current flowing during power assist is increased to the same level as the current flowing during restart in order to calculate the internal resistance RL of the lithium ion storage battery 12 at restart, the power to the vehicle becomes excessive, which affects the vehicle behavior. Will affect.

Therefore, in the present embodiment, the control unit 40 is in a state of applying power from the rotary electric machine 10 to the engine 30 under a low efficiency state in which the efficiency of the rotary electric machine 10 is equal to or less than a predetermined value after the first start of the engine 30 (power running). The lithium ion storage battery 12 is energized by the current flowing at that time. Then, a control process is performed to calculate the internal resistance RL of the lithium ion storage battery 12 from the detection result of the electrical change (current, voltage) of the lithium ion storage battery 12 caused by energization.

As described above, by putting the rotary electric machine 10 into the power running state under the low efficiency state, it is possible to increase the charge / discharge current IL flowing through the lithium ion storage battery 12 while keeping the power to the vehicle from increasing. As a result, the internal resistance RL can be appropriately calculated without affecting the vehicle drive.

Subsequently, the control process according to the present embodiment will be described with reference to FIG. Here, FIG. 2 is a flowchart showing the procedure of the above processing. This process is repeatedly performed by the control unit 40, for example, at a predetermined cycle under the condition that the starter 13 is turned on and the engine 30 is started for the first time.

When the control process is started, first, in step S10, it is determined whether or not the engine speed NE is in a high speed state larger than the predetermined speed Nth. Here, the predetermined rotation speed Nth is the minimum rotation speed of the engine 30 in a high-speed state of the vehicle, that is, a state in which the vehicle does not require power assist, and is, for example, 2000 rotation speeds / minute. If a negative determination is made in step S10, the control process ends without calculating the internal resistance RL.

On the other hand, if an affirmative determination is made in step S10, it is determined in step S12 whether or not the request flag FD is on. Here, the request flag FD is a flag that requests the calculation of the internal resistance RL. Specifically, the request flag FD is turned on once during one trip from when the ignition switch is turned on to when it is turned off. If a negative determination is made in step S12, the control process ends without calculating the internal resistance RL.

On the other hand, if an affirmative determination is made in step S12, power is applied to the engine 30 by driving the rotary electric machine 10 in step S14. That is, the rotary electric machine 10 is put into the power running drive state under the high rotation state of the engine 30. In this embodiment, the process of step S14 corresponds to the "drive control unit".

In step S16, the internal resistance RL of the lithium ion storage battery 12 is calculated. That is, the internal resistance RL of the lithium ion storage battery 12 is calculated when the rotary electric machine 10 is driven by power running under the high rotation state of the engine 30. In this embodiment, the process of step S16 corresponds to the “resistance calculation unit”.

In step S18, it is determined whether the internal resistance RL calculated in step S16 is smaller than the predetermined threshold resistance Rth. Here, the threshold resistance Rth is a resistance value that hinders the restart of the engine 30, and is preset for each temperature of the lithium ion storage battery 12.

If an affirmative determination is made in step S18, the permission flag FP is turned on and the control process is terminated in step S20. Here, the permission flag FP is a flag that permits the restart of the engine 30 by supplying electric power from the lithium ion storage battery 12, and is turned on when the restart is permitted and turned off when the restart is prohibited. On the other hand, if a negative determination is made in step S18, the permission flag FP is turned off and the control process ends in step S22. Therefore, it can be said that the process of step S18 is a process of determining whether or not to allow restart by power supply from the lithium ion storage battery 12 based on the internal resistance RL calculated in step S16. In this embodiment, the process of step S18 corresponds to the "restart determination unit".

Subsequently, FIG. 3 shows an example of control processing. In FIG. 3, (A) shows the transition of the engine speed NE, (B) shows the transition of the high rotation flag FH, and (C) shows the transition of the request flag FD. Further, (D) shows the transition of the charge / discharge current IL, (E) indicates the transition of the voltage between terminals VL, and (F) indicates the transition of the permission flag FP.

Here, the high rotation flag FH is a flag indicating the determination result in step S10 of the control process, and is turned on when a positive determination is made in step S10 and turned off when a negative determination is made in step S10. Further, the charge / discharge current IL is described so that the charge current becomes positive and the discharge current becomes negative. In the present embodiment, the permission flag FP is turned off at the start of the control process.

In the illustrated example, when the engine 30 is started for the first time at time t1 and the vehicle starts running, the engine speed NE becomes the starting speed Ns as shown in FIG. 3A. Here, the starting rotation speed Ns is smaller than the predetermined rotation speed Nth, for example, 1000 rotations / minute.

After that, at time t2, the engine speed NE increases due to the acceleration of the vehicle accompanying the accelerator operation of the user. On the other hand, since the vehicle is in a low speed state in which the engine speed NE is smaller than the predetermined speed Nth, power assist is performed by the rotary electric machine 10 as shown in FIGS. 3 (D) and 3 (E).

After that, at time t3, when the engine speed NE becomes larger than the predetermined speed Nth, the high speed flag FH is turned on as shown in FIG. 3 (B). As a result, the assist condition of the rotary electric machine 10 is no longer satisfied, so that the power assist by the rotary electric machine 10 is stopped.

After that, at time t4, as shown in FIG. 3C, when the request flag FD is turned on, the internal resistance RL of the lithium ion storage battery 12 is calculated. In the present embodiment, under the high rotation state of the engine 30 in which the assist condition of the rotary electric machine 10 is not satisfied, power is applied to the engine 30 by driving the rotary electric machine 10, and the internal resistance RL of the lithium ion storage battery 12 is calculated.

In this case, since the engine 30 is already in a high rotation state, the increase in the engine speed NE is suppressed even if power is applied to the engine 30. That is, the efficiency of the rotary electric machine 10 indicated by the ratio of the increase amount of the engine rotation speed NE to the power applied to the engine 30 becomes a predetermined value or less. In the present embodiment, when the engine speed NE is larger than the predetermined speed Nth, power is applied to the engine 30 by driving the rotary electric machine 10 assuming that the efficiency is low, and the internal resistance RL of the lithium ion storage battery 12 is calculated. To do.

Specifically, first, the charge / discharge current IL and the voltage between terminals VL at time t4 before power is applied to the engine 30 from the rotary electric machine 10 are detected. Hereinafter, the charge / discharge current IL and the voltage between terminals VL at time t4 are referred to as voltage V4 and current I4. The voltage V4 is expressed as the following (Equation 1) by using the open circuit voltage V0 of the lithium ion storage battery 12, the current I4, and the internal resistance RL.

V4 = V0 + I4 × RL ... (Equation 1)
Next, power is applied to the engine 30 by driving the rotary electric machine 10. As a result, the discharge current increases and the voltage VL between terminals decreases. Then, the charge / discharge current IL and the terminal voltage VL are detected at the time t5 when a predetermined elapsed period has elapsed from the time t4. Hereinafter, the charge / discharge current IL and the voltage between terminals VL at time t5 are referred to as voltage V5 and current I5. The voltage V5 is represented by the following (Equation 2) using the open circuit voltage V0 of the lithium ion storage battery 12, the current I5, and the internal resistance RL.

V5 = V0 + I5 × RL ... (Equation 2)
From (Equation 1) and (Equation 2), the internal resistance RL is expressed as the following (Equation 3) by using the voltages V4 and V5 and the currents I4 and I5.

RL = (I4-I5) / (V4-V5) ... (Equation 3)
Hereinafter, the current I4 minus the current I5 is referred to as a differential current ΔI, and the voltage V4 minus the voltage V5 is referred to as a differential voltage ΔV (see FIG. 4). In the present embodiment, the voltage V5 and the current I5 are detected at a plurality of times t5 having different elapsed periods from the time t4, and a plurality of data showing the relationship between the differential current ΔI and the differential voltage ΔV are acquired.

After that, when the request flag FD is turned off at time t6, the application of power from the rotary electric machine 10 to the engine 30 is stopped. Then, the internal resistance RL of the lithium ion storage battery 12 is calculated from the acquired data showing the relationship between the differential current ΔI and the differential voltage ΔV, and it is determined whether the calculated internal resistance RL is smaller than the threshold resistance Rth. In the illustrated example, since the calculated internal resistance RL is smaller than the threshold resistance Rth, the permission flag FP is turned on at time t6 as shown in FIG. 3 (F).

After that, when the vehicle starts decelerating at time t7, the engine speed NE decreases. After that, at time t8, when the engine speed NE becomes smaller than the predetermined speed Nth, the high speed flag FH is turned off.

FIG. 4 is a diagram showing the relationship between the differential current ΔI and the differential voltage ΔV. As shown in FIG. 4, the differential voltage ΔV is linearly proportional to the differential current ΔI, and the larger the differential current ΔI, the larger the differential voltage ΔV. Then, the internal resistance RL is calculated from the slope of the differential voltage ΔV with respect to the differential current ΔI.

Since the differential voltage ΔV is linearly proportional to the differential current ΔI, it is possible to calculate the internal resistance RL by using, for example, the charge / discharge current IL flowing during power assist from time t2 to time t3 in FIG. It is also considered to be.

However, since a large discharge current does not flow during power assist, a large differential current ΔI does not occur. Therefore, as data showing the relationship between the differential current ΔI and the differential voltage ΔV, only the data group DX in the range where the differential current ΔI is small can be acquired. If only the data group DX can be acquired, as shown by the broken line in FIG. 4, the slope of the differential voltage ΔV with respect to the differential current ΔI changes significantly due to the detection error of the voltage detection unit 16 and the current detection unit 15, and the internal resistance RL Cannot be calculated properly.

In the present embodiment, the discharge current flowing through the lithium ion storage battery 12 is increased when the data showing the relationship between the differential current ΔI and the differential voltage ΔV is acquired. As a result, data in a range in which the differential current ΔI is large can be acquired, and as shown by a straight line in FIG. 4, the internal resistance RL can be appropriately calculated regardless of the detection errors of the voltage detection unit 16 and the current detection unit 15.

On the other hand, when the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased, the rotation speed NM of the rotary electric machine 10 increases, and the torque TM of the rotary electric machine 10 increases accordingly. If the power applied to the engine 30, that is, the power to the vehicle becomes excessive due to the increase in the torque TM of the rotary electric machine 10, the vehicle behavior is affected and the vehicle behavior cannot be controlled appropriately.

Therefore, in the present embodiment, the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased under the high rotation state of the engine 30. FIG. 5 is a diagram showing the relationship between the rotation speed NM of the rotary electric machine 10 and the torque TM of the rotary electric machine 10. As shown in FIG. 5, the rotary electric machine 10 has a characteristic that the torque TM becomes smaller as the rotation speed NM is larger. Here, the rotation speed NM is proportional to the engine rotation speed NE, and a state in which the rotation speed NM is large corresponds to a high rotation state of the engine 30. Therefore, when the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased under the high rotation state of the engine 30, the torque TM generated in the rotary electric machine 10 is small, so that the increase in the engine rotation speed NE is suppressed. As a result, the power application to the vehicle is suppressed, and the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

According to the present embodiment described in detail above, the following effects can be obtained.

-In a vehicle having an idling stop function, after the initial start using the electric power of the lead storage battery 11, the restart using the electric power of the lithium ion storage battery 12 is appropriately performed. In this case, it is desirable that the engine 30 is automatically stopped after grasping the state such as deterioration of the lithium ion storage battery 12. In this respect, in the present embodiment, when the rotary electric machine 10 supplies power to the engine 30 by supplying electric power from the lithium ion storage battery 12 in a low efficiency state in which the efficiency of the rotary electric machine 10 is equal to or less than a predetermined value, the lithium ion storage battery 12 The internal resistance RL of the above was calculated. By applying power from the rotary electric machine 10 to the engine 30 under a low efficiency state, the power to the vehicle is not increased as compared with the case where power is applied from the rotary electric machine 10 to the engine 30 under conditions other than the low efficiency state. At the same time, the charge / discharge current IL flowing through the lithium ion storage battery 12 can be increased. As a result, the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

The rotary electric machine 10 performs power assist when a predetermined assist condition is satisfied, and does not perform power assist when the assist condition is not satisfied. In the present embodiment, power is applied from the rotary electric machine 10 to the engine 30 in a low efficiency state during the rest period of the rotary electric machine 10 without the power assist, and the internal resistance RL of the lithium ion storage battery 12 is calculated. As a result, the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated by effectively utilizing the rotary electric machine 10 during the rest period.

-Specifically, when the engine speed NE is larger than the predetermined speed Nth, the suspension period of the rotary electric machine 10 (time t3 to t8 in FIG. 3) is set. In this rest period, since the engine speed NE is larger than the predetermined speed Nth, the amount of increase in the engine speed NE due to the power application to the vehicle is suppressed as compared with the case where the engine speed NE is smaller than the predetermined speed Nth. That is, the efficiency of the rotary electric machine 10 becomes a predetermined value or less. Therefore, by calculating the internal resistance RL of the lithium ion storage battery 12 during this pause period, the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

-In the present embodiment, it is determined whether or not the restart of the engine 30 by the power supply from the lithium ion storage battery 12 is permitted based on the calculated internal resistance RL. Therefore, the idling stop control can be appropriately performed after grasping the state such as deterioration of the lithium ion storage battery 12.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 6 and 7, focusing on the differences from the first embodiment.

In the present embodiment, the control process is different from that of the first embodiment. The control process of the present embodiment is different from the control process of the first embodiment in that the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased based on the temperature YM of the rotary electric machine 10.

FIG. 6 shows a flowchart of the control process according to the present embodiment. In FIG. 6, the same processing as that shown in FIG. 2 above is designated by the same reference numerals for convenience, and the description thereof will be omitted.

In the present embodiment, when the control process is started, first, in step S30, it is determined whether or not the temperature YM of the rotary electric machine 10 is in a high temperature state higher than the predetermined temperature Yth. Here, the predetermined temperature Yth is the lowest temperature at which the heat loss HL of the rotary electric machine 10 becomes excessive and the efficiency of the rotary electric machine 10 becomes equal to or less than a predetermined temperature. If a negative determination is made in step S10, the control process ends without calculating the internal resistance RL. On the other hand, if an affirmative determination is made in step S10, the process proceeds to step S12.

In the present embodiment, the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased under the high temperature state of the rotary electric machine 10. FIG. 7 is a diagram showing the relationship between the temperature YM of the rotary electric machine 10 and the heat loss HL of the rotary electric machine 10. As shown in FIG. 7, the rotary electric machine 10 has a characteristic that the higher the temperature YM, the larger the heat loss HL. Therefore, when the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased under the high temperature state of the rotary electric machine 10, the increase in the engine speed NE is suppressed due to the large heat loss HL, and the power application to the vehicle is suppressed. To. As a result, the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

-According to the present embodiment described above, the internal resistance RL of the lithium ion storage battery 12 is calculated when the temperature YM of the rotary electric machine 10 is higher than the predetermined temperature Yth. When the temperature YM of the rotary electric machine 10 is higher than the predetermined temperature Yth, the engine speed due to the power to the vehicle is compared with the case where the temperature YM of the rotary electric machine 10 is lower than the predetermined temperature Yth due to the heat loss HL of the rotary electric machine 10. The amount of increase in NE is suppressed. That is, the efficiency of the rotary electric machine 10 becomes a predetermined value or less. Therefore, by calculating the internal resistance RL of the lithium ion storage battery 12 in the high temperature state of the rotary electric machine 10, the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

(Third Embodiment)
Hereinafter, the third embodiment will be described with reference to FIG. 8, focusing on the differences from the first embodiment.

In the present embodiment, the control process is different from that of the first embodiment. In the control process of the present embodiment, when the charge / discharge current IL flowing through the lithium ion storage battery 12 is increased, the current flows only in the d-axis of the d-axis and the q-axis of the rotary electric machine 10. Different from control processing.

FIG. 8 shows a flowchart of the control process according to the present embodiment. In FIG. 8, the same processing as that shown in FIG. 2 above is designated by the same reference numerals and the description thereof will be omitted for convenience.

In the present embodiment, when the control process is started, first, in step S12, it is determined whether or not the request flag FD is on. If a negative determination is made in step S12, the control process ends without calculating the internal resistance RL.

On the other hand, if an affirmative determination is made in step S12, the q-axis current Iq of the rotary electric machine 10 is set to zero in step S40, and the process proceeds to step S14. As a result, when the rotary electric machine 10 is put into the power running drive state in step S14, only the d-axis current Id flows through the rotary electric machine 10. In the "power running drive state", in addition to the state in which the armature winding of the rotary electric machine 10 is energized so as to apply power from the rotary electric machine 10 to the engine 30, the power to the engine 30 is supplied. It includes a state in which energization is performed in a state where no application occurs.

In the present embodiment, only the d-axis current Id is passed through the rotary electric machine 10 to increase the charge / discharge current IL flowing through the lithium ion storage battery 12. When only the d-axis current Id flows through the rotary electric machine 10, torque TM is not generated in the rotary electric machine 10, so that the increase in the engine speed NE is suppressed. As a result, the power application to the vehicle is suppressed, and the internal resistance RL of the lithium ion storage battery 12 can be appropriately calculated without affecting the vehicle drive.

-According to the present embodiment described above, the internal resistance RL of the lithium ion storage battery 12 is calculated in a state where only the d-axis current Id flows through the rotary electric machine 10. In a state where only the d-axis current Id flows through the rotary electric machine 10, torque TM is not generated in the rotary electric machine 10, so that the amount of increase in the engine speed NE is suppressed. That is, the efficiency of the rotary electric machine 10 becomes a predetermined value or less. Therefore, by calculating the internal resistance RL of the lithium ion storage battery 12 in a state where only the d-axis current Id flows through the rotary electric machine 10, the internal resistance RL of the lithium ion storage battery 12 is appropriately calculated without affecting the vehicle drive. it can.

-In the present embodiment, since the torque TM is not generated in the rotary electric machine 10, the internal resistance RL of the lithium ion storage battery 12 can be calculated even when the vehicle is stopped. Therefore, the internal resistance RL of the lithium ion storage battery 12 can be calculated in the period after the engine 30 is started for the first time and before the restart using the electric power of the lithium ion storage battery 12 is performed.

(Other embodiments)
The present invention is not limited to the contents described in the above embodiments, and may be implemented as follows.

-In the above embodiment, an example is shown in which the lead storage battery 11 is used for the first start of the engine 30 and the lithium ion storage battery 12 is used for the start of the engine 30, but the type of battery used for each start is the same. Not exclusively. When the engine 30 is started for the first time, a storage battery capable of outputting a stable voltage against a large current discharge at the time of the first start may be used, and when the engine 30 is restarted, the durability against cumulative charge / discharge is high. A storage battery may be used. For example, as the second storage battery, a nickel hydrogen storage battery may be used. Further, the first storage battery and the second storage battery may be the same type of storage battery.

-In the above embodiment, the rotary electric machine 10 has both the power generation function and the power running function, but the rotary electric machine 10 may have only the power running function.

-In the above embodiment, as the low efficiency state, the high rotation state of the engine 30, the high temperature state of the rotary electric machine 10, and the state in which only the d-axis current Id flows through the rotary electric machine 10 are separately used. It may be used in combination. For example, when two of these three states are satisfied, it may be determined that the efficiency state is low. Specifically, power may be applied from the rotary electric machine 10 to the engine 30 under a high rotation state of the engine 30 and a high temperature state of the rotary electric machine 10 to increase the charge / discharge current IL flowing through the lithium ion storage battery 12. ..

-Also, these three states may be used in a complementary manner. For example, if it is determined that neither the high rotation state of the engine 30 nor the high temperature state of the rotary electric machine 10 is reached within a predetermined period after the first start of the engine 30, only the d-axis current Id is applied to the rotary electric machine 10. May be in a flowing state. As a result, it is easy to calculate the internal resistance RL of the lithium ion storage battery 12 in the period after the engine 30 is started for the first time and before the restart using the electric power of the lithium ion storage battery 12 is performed.

-In the above embodiment, an example is shown in which the internal resistance RL of the lithium ion storage battery 12 is used for determining whether or not to allow the restart of the engine 30 by supplying electric power from the lithium ion storage battery 12, but the present invention is not limited to this. For example, it may be used for other purposes such as deterioration determination of the lithium ion storage battery 12.

-In the above embodiment, an example is shown in which the engine 30 is not restarted when the internal resistance RL of the lithium ion storage battery 12 is equal to or higher than the threshold resistance Rth, but the present invention is not limited to this. For example, the engine 30 may be restarted by supplying electric power from the lead storage battery 11 instead of the lithium ion storage battery 12. As a result, idling stop control can be appropriately performed even in a deteriorated state of the lithium ion storage battery 12.

-There is a correlation between the internal resistance RL of the lithium ion storage battery 12 and the temperature of the lithium ion storage battery 12. Therefore, in the first embodiment, a temperature detection unit for detecting the temperature of the lithium ion storage battery 12 may be provided, and the calculated internal resistance RL may be corrected based on the temperature detection result by the temperature detection unit. For example, the internal resistance RL is corrected so as to decrease as the temperature of the lithium ion storage battery 12 increases. As a result, the calculation accuracy of the internal resistance RL can be improved.

-In the first embodiment, the timing at which the request flag FD is turned on may be earlier than the timing at which the high rotation flag FH is turned on. For example, the request flag FD may be turned on at the same time that the engine 30 is started for the first time. As a result, the internal resistance RL of the lithium ion storage battery 12 can be calculated at an early stage.

10 ... rotary electric machine, 11 ... lead storage battery, 12 ... lithium ion storage battery, 30 ... engine, 40 ... control unit, 100 ... power supply system.

Claims (7)

A first storage battery that is mounted on a vehicle that automatically stops and restarts the engine (30) according to predetermined conditions, is connected in parallel to the rotary electric machine (10), and is used to supply electric power when the engine is first started. A power supply device (40) applied to a power supply system (100) including (11) and a second storage battery (12) used for power supply when the engine is restarted after being automatically stopped. ,
After the engine is started for the first time, a drive control unit that puts the rotary electric machine into a power running state by supplying electric power from the second storage battery under a low efficiency state in which the efficiency of the rotary electric machine is equal to or less than a predetermined value.
A power supply device including a resistance calculation unit that calculates the internal resistance of the second storage battery when the rotary electric machine is put into a power running state under the low efficiency state by the drive control unit. The rotary electric machine performs power assist when a predetermined assist condition is satisfied while the vehicle is traveling.
The power supply device according to claim 1, wherein the drive control unit puts the rotary electric machine into a power running drive state under the low efficiency state when the assist condition is not satisfied. The power supply device according to claim 1 or 2, wherein the drive control unit puts the rotary electric machine into a power running drive state as being in the low efficiency state when the engine speed is higher than a predetermined rotation speed. Any one of claims 1 to 3 in which the drive control unit puts the rotary electric machine into a power running drive state as being in the low efficiency state when the temperature of the rotary electric machine is higher than a predetermined temperature. The power supply according to the section. The drive control unit according to any one of claims 1 to 4, wherein the rotary electric machine is brought into a power driving state in a state where a current is passed only on the d-axis of the d-axis and the q-axis of the rotary electric machine. The power supply described. Claims 1 to 5 include a restart determination unit that determines whether or not to permit the restart by supplying power from the second storage battery based on the internal resistance calculated by the resistance calculation unit. The power supply device according to any one item. A power supply system (100) mounted on a vehicle that automatically stops and restarts the engine (30) according to predetermined conditions.
Rotating electric machine (10) and
A first storage battery (11) connected in parallel to the rotary electric machine and used to supply electric power at the first start of the engine.
A second storage battery (12) used to supply electric power when restarting the engine after it is automatically stopped.
After the engine is started for the first time, a drive control unit that puts the rotary electric machine into a power running state by supplying electric power from the second storage battery under a low efficiency state in which the efficiency of the rotary electric machine is equal to or less than a predetermined value.
A power supply system including a resistance calculation unit that calculates the internal resistance of the second storage battery when the rotary electric machine is put into a power running state under the low efficiency state by the drive control unit.

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