Electric system

Abstract

To effectively raise temperature of a power storage device with a simple configuration.SOLUTION: An electric system comprises a battery 12, an inverter 40 and an actuator 30. The inverter 40 is connected to the battery 12 through power lines PL and NL. The actuator 30 adjusts an interval between the power lines PL and NL. When a temperature rise start condition for starting a temperature rise of the battery 12 is satisfied, the actuator 30 adjusts the interval so that a ripple of a current Ib of the battery 12 increases.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrical system.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2011-155788 (Patent Document 1) discloses an electric vehicle. This electric vehicle includes a power storage device (secondary battery), a boost converter, an inverter, a motor, and a control device. The boost converter is connected to the power storage device and boosts the power output from the power storage device. The inverter converts the boosted DC power into AC power. The motor receives this AC power and generates a driving force for the vehicle to travel. The control device heats up the power storage device by controlling the boost converter so that the ripple of the current flowing through the power storage device increases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above electric vehicle, a boost converter is used to heat up the power storage device. However, there may be a case where a boost converter is not provided in the electric vehicle. Even in such a case, a technique for effectively heating up the power storage device is desired.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an electrical system for effectively heating up a power storage device with a simple configuration.

Means for Solving the Problems

[0006] The electrical system of the present disclosure includes a power storage device, an inverter, and an adjustment device. The inverter is connected to the power storage device through a pair of power lines. The adjustment device adjusts the interval between the pair of power lines. When a temperature increase start condition for starting the temperature increase of the power storage device is satisfied, the adjustment device adjusts the interval so that the ripple of the current of the power storage device increases.

[0007] With the above configuration, the interval is adjusted by the adjustment device, and the ripple increases. As a result, the power loss of the power storage device increases due to the internal resistance of the power storage device. As a result, the amount of heat generation can be increased when the temperature of the power storage device rises. Therefore, the power storage device can be effectively heated with a simple configuration.

Advantages of the Invention

[0008] According to the present disclosure, the power storage device can be effectively heated with a simple configuration.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. Each of the embodiments and their modifications may be combined with each other as appropriate.

[0011] FIG. 1 is an overall configuration diagram of a vehicle equipped with an electrical system according to the present embodiment. Referring to FIG. 1, vehicle 1 is assumed to be a battery electric vehicle (BEV), but may be another type of electric vehicle such as a plug-in hybrid electric vehicle (PHEV). Vehicle 1 includes an electrical circuit 10, an actuator 30, an inverter 40, current sensors 45u, 45v, 45w, a motor 50, and a control device 80.

[0012] Electrical circuit 10 includes a battery unit 11 and a capacitor 38. Battery unit 11 includes a battery 12, a sensor group 15, and a system main relay (SMR) 17. Battery 12 is a secondary battery such as a lithium-ion battery and corresponds to an example of the "power storage device" of the present disclosure. The direct current output from battery 12 is also represented as "current Ib". Sensor group 15 includes various sensors for detecting various physical quantities of battery 12 (for example, current Ib, voltage, and temperature Tb). When temperature Tb decreases, the performance of battery 12 may decrease and current Ib may decrease. In this case, the driving force of vehicle 1 may decrease. SMR 17 is connected to battery 12. When SMR 17 is on, battery 12 is connected to power lines PL, NL (power line pair). Power lines PL, NL are wire harnesses provided to connect battery 12 to an inverter 40 (described later).

[0013] Capacitor 38 is connected between power lines PL, NL. Capacitor 38 is provided to smooth the current ripple (for example, the ripple of current Ib) superimposed on power lines PL, NL due to the operation of inverter 40.

[0014] The above ripple frequency and amplitude are also referred to as the "ripple frequency" and the "ripple amplitude Ra", respectively. The ripple amplitude Ra is an example of an index representing the magnitude of the above ripple. The larger the ripple amplitude Ra, the larger the input / output current of the battery 12, and thus the larger the power loss due to the internal resistance of the battery 12. As a result, the heat generation amount of the battery 12 is large. The ripple amplitude Ra also depends on the impedance (transmission characteristics) of the power lines PL and NL. This point will be described later.

[0015] The actuator 30 is an adjustment device that adjusts the distance between the power lines PL and NL, and is disposed between the power lines PL and NL. The detailed configuration of the actuator 30 will be described in detail later.

[0016] The inverter 40 is connected to the battery 12 through the power lines PL and NL and the SMR 17, and includes switching elements Q1 to Q6 and diodes D1 to D6. The switching elements Q1 to Q6 are, for example, IGBTs (insulated-gate bipolar transistors), but may also be MOSFETs (metal-oxide-semiconductor field-effect transistors). The diodes D1 to D6 are respectively provided in antiparallel with the switching elements Q1 to Q6. The inverter 40 converts the DC current from the electric circuit 10 by switching the switching elements Q1 to Q6 to generate an AC current. The AC current is the U-phase current (current Iu), V-phase current, or W-phase current of the motor 50. The switching frequency of the switching elements Q1 to Q6 (the carrier frequency of the inverter 40) affects the ripple frequency.

[0017] The motor 50 is a permanent magnet synchronous motor connected to the inverter 40, and can generate a driving force for the vehicle 1 to travel by receiving the AC current from the inverter 40.

[0018] The current sensors 45u, 45v, and 45w detect the U-phase current, V-phase current, and W-phase current of the motor 50, respectively. These currents are collectively referred to as the "motor current". The peak-to-peak value of each motor current is also denoted as the "peak-to-peak value Vpp". This value is an example of an index representing the magnitude of the motor current.

[0019] The control device 80 includes a battery ECU (Electronic Control Unit) 82, an inverter ECU 84, and a vehicle ECU (upper ECU) 86. The battery ECU 82 monitors the state of the battery 12 according to the detection results of the sensor group 15. The inverter ECU 84 controls the inverter 40. Specifically, the inverter ECU 84 generates drive signals S1 to S6 according to the detection results of the current sensors 45u, 45v, and 45w, and thereby performs on / off control of the switching elements Q1 to Q6. The vehicle ECU 86 manages the battery ECU 82 and the inverter ECU 84 and controls the entire vehicle 1. The vehicle ECU 86 controls, for example, the actuator 30 or controls the battery ECU 82 and the inverter ECU 84.

[0020] The control device 80 calculates an amplification factor af of the ripple amplitude Ra with respect to the peak-to-peak value Vpp according to the detection results of the sensor group 15 and the current sensors 45u, 45v, and 45w. The higher the amplification factor af, the larger the ripple amplitude, and thus the larger the heat generation amount of the battery 12.

[0021] Figure 2 is a diagram for explaining the detailed configuration of the actuator 30. Referring to Figure 2(A), the actuator 30 includes link mechanisms 32A to 32C, a gear 34, and a gear motor (not shown). The link mechanisms 32A to 32C are connected to the power line PL and operate in conjunction with the gear 34. In this example, since the link mechanisms 32A to 32C are folded, the distance D between the power lines PL and NL is d1. The gear 34 is connected to the gear motor and is rotated by the drive of this motor. Thus, the actuator 30 can be realized with a simple configuration. The state of the actuator 30 when the distance D is d1 is also referred to as the "non-operating state".

[0022] Referring to Fig. 2(B), when the rotation of gear 34 is started by the drive start of the gear motor, gear 34 contacts power line NL, and link mechanisms 32A to 32C start to extend in the direction from power line PL to power line NL. As a result, in this example, interval D is expanded to d2 (>d1). Referring to Fig. 2(C), when link mechanisms 32A to 32C are fully extended thereafter, the angle θ between link mechanisms 32B and 32C reaches 180°, and the gear motor is stopped. In this case, interval D is expanded to d3 (>d2), which is its maximum value. The state of actuator 30 when interval D is d2 or d3 is also referred to as the "operating state". Note that when the gear motor is started to drive in the reverse direction and gear 34 is rotated in the reverse direction in the operating state, link mechanisms 32A to 32C start to contract in the direction from power line NL to power line PL. As a result, interval D finally returns to d1. Thus, the gear motor functions as a telescopic mechanism capable of extending and contracting link mechanisms 32A to 32C in the direction from one of power lines PL and NL to the other.

[0023] In the embodiment, link mechanisms 32A to 32C and gear 34 are arranged in the central portion of the routing space of power lines PL and NL. Thereby, interval D can be effectively expanded in the operating state of actuator 30.

[0024] Fig. 3 is a diagram showing the frequency characteristics of amplification factor af and the frequency characteristics of ripple amplitude. Referring to Fig. 3(A), lines 105 and 110 respectively represent the frequency characteristics of amplification factor af when interval D is d1 and d3. Range RNG is the frequency range from f1 to f2. This range corresponds to the frequency range in which the amplification factor af (line 110) when interval D is d3 is higher than the amplification factor af (line 105) when interval D is d1. f1 and f2 are stored in the memory of control device 80.

[0025] Referring to FIG. 3(B), line 205 (dashed-dotted line) and line 210 (solid line) respectively represent the frequency characteristics of the ripple amplitude when the interval D is d1 and d3. Outside the range RNG, it is assumed that line 210 is substantially the same as line 205. On the other hand, within the range RNG, line 210 is significantly different from line 205. Specifically, the ripple amplitude (line 210) when the interval D is d3 is larger than the ripple amplitude (line 205) when the interval D is d1. Thus, the frequency characteristics of the ripple amplitude change depending on the interval D.

[0026] There is a demand for a technique to effectively raise the temperature of the battery 12 when the temperature Tb drops. Therefore, in the present embodiment, when the temperature-raising start condition for starting the temperature-raising of the battery 12 is satisfied, the control device 80 controls the actuator 30 to perform an adjustment operation of adjusting the interval D so that the ripple amplitude increases. The temperature-raising start condition is, for example, that the temperature Tb is lower than a predetermined threshold temperature. The above adjustment operation corresponds to, for example, when the ripple frequency is within the range RNG, the gear motor operates so that the link mechanisms 32A to 32C extend (the interval D widens).

[0027] According to the above adjustment operation, the interval D is adjusted (widened) by the actuator 30, and the impedance (transmission characteristics) of the power lines PL and NL changes so that the mutual inductance of the power lines PL and NL changes (increases). As a result, the ripple amplitude Ra increases (line 210), and the power loss of the battery 12 increases due to the internal resistance of the battery 12. Therefore, the amount of heat generated when the temperature of the battery 12 rises can be increased. In addition, the embodiment does not necessarily require a boost converter and can be realized by mounting the actuator 30 on the vehicle 1. Therefore, the battery 12 can be effectively heated with a simple configuration. Thus, it is possible to prevent a decrease in the driving force of the vehicle 1 due to a decrease in the temperature Tb while shortening the time required to raise the temperature of the battery 12.

[0028] FIG. 4 is a flowchart illustrating the processing executed by the control device 80. Referring to FIG. 4, the control device 80 determines whether the temperature Tb of the battery 12 is less than the above-described threshold temperature (S105).

[0029] When the temperature Tb is equal to or higher than the threshold temperature (NO in S105), the control device 80 controls the actuator 30 to be in a non-operating state (S110). For example, the control device 80 controls the gear motor so that the interval D becomes d1.

[0030] When the temperature Tb is less than the threshold temperature (YES in S105), the control device 80 controls the actuator 30 to be in an operating state to raise the temperature of the battery 12 (S115). For example, the control device 80 controls the gear motor so that the interval D becomes d3.

[0031] As described above, according to the embodiment, the battery 12 can be effectively heated with a simple configuration.

[0032] [Modification Example] The control device 80 may control the actuator 30 to perform an adjustment operation according to the target value of the increase amount of the temperature Tb when the temperature of the battery 12 is rising. For example, when the target value is relatively low (the temperature increase amount is small), the control device 80 adjusts the interval D to d2, and when the target value is relatively high (the temperature increase amount is large), the control device 80 controls the actuator 30 to adjust the interval D to d3.

[0033] It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0034] 1 Vehicle, 12 Battery, 15 Sensor Group, 30 Actuator, 38 Capacitor, 40 Inverter, 50 Motor, 80 Control Device, NL, PL Power Line.

Claims

【Claim 1】 An electrical storage device, an inverter connected to the electrical storage device through a power line pair, and an adjustment device for adjusting the distance between the power line pairs, wherein when a temperature rise start condition for starting a temperature rise of the electrical storage device is satisfied, the adjustment device adjusts the distance so that a ripple of a current of the electrical storage device increases. An electrical system.

Images