AC voltage output devices, AC voltage output systems, and vehicles

Abstract

To provide an in-vehicle AC voltage output device, AC voltage output system, and vehicle capable of supporting idle stop. [Solution] The lithium battery 4 is installed under the floor of the vehicle, and the remainder is housed in a junction box as an AC voltage output device. The AC voltage output system 100, which is installed in an appropriate location inside the vehicle such as near the driver's seat, includes an inverter 1 that can receive a DC voltage from an auxiliary battery 21, which is an on-board battery, via an auxiliary battery relay 11, and a DC voltage from a lithium battery 4, which is a secondary battery, via a lithium battery relay 13, and generates and outputs an AC voltage from the input DC voltage; a lithium charger 3 that charges the lithium battery with the AC voltage from the inverter via a charger relay 12; and an AC voltage output unit 2 that outputs the AC voltage from the inverter.

Description

Technical Field

[0007] , , ,

[0006] , , , , ,

[0001] The present invention relates to an AC voltage output device, an AC voltage output system, and a vehicle.

Background Art

[0002] In recent years, awareness of environmental problems has been increasing, and for example, vehicle idling stop is required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem of the present invention is to provide a new AC voltage output device, for example, an in-vehicle AC voltage output device capable of coping with idling stop.

Means for Solving the Problems

[0005] As an example, the following invention is disclosed.

[0006] [1] An inverter that can input a DC voltage from an in-vehicle battery via a first switch and can input a DC voltage from a secondary battery via a second switch, and generates and outputs an AC voltage from the input DC voltage, A charger that charges the secondary battery with the AC voltage from the inverter via a third switch, An AC voltage output device including an AC voltage output unit that outputs the AC voltage from the inverter.

[0007] [2] The AC voltage output device according to [1], further comprising a control unit for controlling the on / off state of the first switch, the second switch, and the third switch.

[0008] [3] The control unit controls the on / off state of the first switch, the second switch, and the third switch based on the DC voltage from the vehicle battery, as described in [2].

[0009] [4] The AC voltage output device according to [2] or [3], wherein the control unit controls the on / off switching of the first switch and the second switch so that the output of AC voltage from the AC voltage output unit is not interrupted.

[0010] [5] The control unit, If the DC voltage from the vehicle battery exceeds a first threshold, the first switch is turned on, the second switch is turned off, and the third switch is turned on. The AC voltage output device according to [2] to [4], wherein the DC voltage from the vehicle battery does not exceed a first threshold, the first switch is turned off, the second switch is turned on, and the third switch is turned off.

[0011] [6] The control unit, when the vehicle on which the AC voltage output device is installed is stopped, turns off the first switch, turns on the second switch, and turns off the third switch, according to any one of [2] to [5], the AC voltage output device.

[0012] [7] The AC voltage output device according to [2], wherein the control unit controls the on / off state of the first switch, the second switch, and the third switch based on the DC voltage from the vehicle battery and the DC voltage from the secondary battery.

[0013] [8] When the DC voltage from the in - vehicle battery transitions from a state exceeding the first threshold value to a state not exceeding the first threshold value, first, the control unit turns on the second switch from off, and then, after a delay time corresponding to the difference between the DC voltage from the secondary battery and the DC voltage from the in - vehicle battery, turns off the first switch from on. The AC voltage output device according to [7].

[0014] [9] The greater the voltage difference Dv of the following formula, the shorter the delay time. The AC voltage output device according to [8]. Dv = DC voltage from the secondary battery - DC voltage from the in - vehicle battery.

[0015]

[10] The delay time is set so that when the voltage output by the in - vehicle battery transitions from a state exceeding the first threshold value to a state not exceeding the first threshold value, the DC voltage input to the inverter does not fall below the second threshold value. The AC voltage output device according to [8] or [9].

[0016]

[11] When the input DC voltage of the inverter is below the output cut - off voltage, the inverter does not output an AC voltage normally. The second threshold value is equal to or higher than the output cut - off voltage. The AC voltage output device according to

[10] .

[0017]

[12] An AC voltage output system including the secondary battery and the AC voltage output device according to any one of [1] to

[11] .

[0018]

[13] A vehicle including the in - vehicle battery and the AC voltage output system according to

[12] .

Brief Description of the Drawings

[0019] [Figure 1] A block diagram showing the schematic configuration of the AC voltage output system 100 according to the first embodiment. [Figure 2]A diagram for explaining the on / off control of relays 11 to 13 by the system controller 20. [Figure 3A] A diagram for explaining the operating state of the AC voltage output system in state 1. [Figure 3B] A diagram for explaining the operating state of the AC voltage output system in states 2-1 and 2-2. [Figure 4] A diagram schematically showing an example of the switching timing of relays 11 and 13. [Figure 5] A diagram for explaining the operating state of the AC voltage output system. [Figure 6] A block diagram showing the schematic configuration of the AC voltage output system 100 according to the second embodiment. [Figure 7A] A diagram for explaining an example of the switching timing of relays 11 and 13. [Figure 7B] A diagram for explaining another example of the switching timing of relays 11 and 13. [Figure 8] A diagram exemplifying the relationship between the voltage difference Dv and the delay time Dt.

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

[0021] (First Embodiment) FIG. 1 is a block diagram showing the schematic configuration of the AC voltage output system 100 according to the first embodiment. The AC voltage output system 100 may include an inverter 1, an AC voltage output unit 2, a lithium charger 3, a lithium battery 4, an auxiliary battery relay 11, a charger relay 12, a lithium battery relay 13, a system controller 20, and the like.

[0022] As a typical example, this AC voltage output system 100 is mounted in a vehicle. Specifically, the lithium battery 4 of the AC voltage output system 100 is installed under the vehicle floor, and the remainder is housed in a junction box as an AC voltage output device, which can be installed in an appropriate location inside the vehicle, such as near the driver's seat. The AC voltage output system 100 is then connected to the vehicle's original auxiliary battery 21 and alternator 22. Here, the auxiliary battery 21 is charged by the alternator 22, and when sufficiently charged, it outputs a DC voltage of approximately 24V.

[0023] The connections of each part are as follows: The positive terminal of the auxiliary battery 21 is connected to one end of the auxiliary battery relay 11. It can also be said that the alternator 22 is connected to one end of the auxiliary battery relay 11. The other end of the auxiliary battery relay 11 is connected to the input terminal of the inverter 1. The output terminal of the inverter 1 is connected to both the AC voltage output unit 2 and the input terminal of the lithium charger 3. The output terminal of the lithium charger 3 is connected to one end of the charger relay 12. The other end of the charger relay 12 is connected to the positive terminal of the lithium battery 4.

[0024] The positive terminal of the lithium battery 4 is also connected to one end of the lithium battery relay 13. The other end of the lithium battery relay 13 is connected to the input terminal of the inverter 1. That is, the other end of the auxiliary battery relay 11 and the other end of the lithium battery relay 13 are connected to the input terminal of the inverter 1. The AC voltage output system 100 may also include a pre-charge relay 14 and a resistor R connected in series between the positive terminal of the lithium battery 4 and the input terminal of the inverter 1.

[0025] The positive terminal of the auxiliary battery 21 is connected to the system controller 20. Alternatively, the alternator 22 is connected to the system controller 20. A signal (e.g., a vehicle speed pulse signal) that can be used to determine whether the vehicle is stopped may also be input to the system controller 20. The system controller 20 controls the on / off state of relays 11-14 based on the DC voltage from the auxiliary battery 21 and whether the vehicle is stopped. Although not shown in the diagram, the DC voltage from the lithium battery 4 may be output externally and made available for use.

[0026] The negative terminals of the lithium battery 4 and the auxiliary battery 21 are commonly grounded (not shown). In this specification, "A and B are connected" includes cases where A and B are directly connected by conductive materials such as wiring, and cases where they are indirectly connected via some electrical component. The lithium battery 4 is an example of a secondary battery. The auxiliary battery 21 is an example of an on-board battery. Relays 11-14 are examples of switches.

[0027] With the above connection configuration, the inverter 1 can receive a DC voltage from the auxiliary battery 21 (alternator 22) via the auxiliary battery relay 11, and a DC voltage (for example, 28V) from the lithium battery 4 via the lithium battery relay 13.

[0028] Inverter 1 converts the input DC voltage into a 100V AC voltage and outputs it to both the AC voltage output unit 2 and the lithium charger 3. The AC voltage output unit 2 outputs the 100V AC voltage from inverter 1 and is a so-called outlet. The lithium charger 3 generates and outputs the DC voltage necessary to charge the lithium battery 4 using the AC voltage from inverter 1 via the charger relay 12.

[0029] Figure 2 illustrates the on / off control of relays 11-13 by the system controller 20. The system controller 20 controls relays 11-13 in the following manner to ensure that the 100V AC voltage output from the AC voltage output unit 2 is not interrupted.

[0030] The system controller 20 determines whether the auxiliary battery 21 is sufficiently charged. As an example of this determination, if the DC voltage from the auxiliary battery 21 exceeds a predetermined threshold (for example, 23.5V), it is determined that the battery is sufficiently charged.

[0031] If the auxiliary battery 21 is sufficiently charged (State 1 in Figure 2), the system controller 20 turns on the auxiliary battery relay 11 and the charger relay 12, and turns off the lithium battery relay 13 and the precharge relay 14.

[0032] In state 1, as shown in Figure 3A, a DC voltage from the auxiliary battery 21 (alternator 22) is supplied to the inverter 1. This DC voltage generates a 100V AC voltage, which is output from the AC voltage output unit 2. The lithium battery 4 is also charged by the lithium charger 3, which is supplied with a 100V AC voltage. When the auxiliary battery 21 is sufficiently charged, power is supplied from the auxiliary battery 21 (alternator 22), allowing for stable output of a 100V AC voltage while charging the lithium battery 4.

[0033] If the auxiliary battery 21 is not sufficiently charged (State 2-1 in Figure 2), the system controller 20 turns off the auxiliary battery relay 11 and the charger relay 12, and turns on the lithium battery relay 13. Alternatively, the system controller 20 may first briefly turn on the pre-charge relay 14, and then turn on the lithium battery relay 13 (the on periods of both relays 14 and 13 will slightly overlap). By first supplying power from the lithium battery 4 to the inverter 1 via the resistive element R, a large instantaneous current flowing into the inverter 1 can be suppressed.

[0034] The system controller 20 also determines whether the vehicle is stopped or not. As an example of this determination, if the vehicle speed based on the vehicle speed pulse signal is below a predetermined threshold, the system controller 20 determines that the vehicle is stopped. When it is determined that the vehicle is stopped (state 2-2), the system controller 20 controls relays 11-13 in the same way as in state 2-1, regardless of whether the auxiliary battery 21 is sufficiently charged or not.

[0035] In states 2-1 and 2-2, as shown in Figure 3B, a DC voltage is supplied from the lithium battery 4 to the inverter 1. This DC voltage generates a 100V AC voltage, which is output from the AC voltage output unit 2. In this way, even if the auxiliary battery 21 is not sufficiently charged, or if the vehicle is stopped and the alternator 22 does not charge the auxiliary battery 21, a 100V AC voltage can be output by power supply from the lithium battery 4.

[0036] In this embodiment, the output of the inverter 1 is connected to both the AC voltage output unit 2 and the lithium charger 3. This makes it possible to output a 100V AC voltage using power from the auxiliary battery 21 (alternator 22) and charge the lithium battery 4, as well as output a 100V AC voltage using power from the lithium battery 4, with a single inverter 1.

[0037] The AC voltage output system 100 described above can be installed in vehicles such as medium and large trucks as a sub-battery system. Even when the vehicle is stopped, it can output 100V AC voltage using power from the lithium battery 4, thus promoting idle stop. Furthermore, when the vehicle is stopped or the auxiliary battery 21 is not sufficiently charged, the power from the auxiliary battery 21 is not used, thus reducing the risk of vehicle operation problems.

[0038] (Second Embodiment) The second embodiment described below relates to the switching timing of relays 11 and 13 when the AC voltage output system 100 described in the first embodiment transitions from state 1 in Figure 2 to state 2-1 or state 2-2 (hereinafter collectively referred to as "state 2"). In this transition, the system controller 20 switches the auxiliary battery relay 11 from on to off and the lithium battery relay 13 from off to on.

[0039] Figure 4 schematically shows an example of the switching timing of relays 11 and 13. This figure shows an example where, at time t1, the auxiliary battery relay 11 is switched from on to off, and at the same time, the lithium battery relay 13 is switched from on to off.

[0040] Before time t1, the auxiliary battery relay 11 is ON, so a DC voltage (for example, about 24V) from the auxiliary battery 21 is input to the inverter 1. When the auxiliary battery relay 11 turns OFF at time t1 (Figure 4(a)), the DC voltage from the auxiliary battery 21 (alternator 22) is no longer input to the inverter 1. At time t1, the lithium battery relay 13 turns ON (Figure 4(b)), but the DC voltage (for example, about 28V) from the lithium battery 4 is not immediately input to the inverter 1.

[0041] Therefore, the DC voltage input to inverter 1 initially decreases from time t1, and then increases (Figure 4(c)). If the DC voltage input to inverter 1 falls below the output cutoff voltage Vth of inverter 1, inverter 1 will not be able to output a normal 100V AC voltage. For example, suppose the DC voltage input to inverter 1 falls below the output cutoff voltage Vth at time t2, and then exceeds the output cutoff voltage Vth at time t3 due to the DC voltage from lithium battery 4. In that case, a normal 100V AC voltage will not be output from time t2 to t3 (Figure 4(d)).

[0042] Thus, switching relays 11 and 13 simultaneously may result in a period during which a normal 100V AC voltage is not output. If such a period is acceptable, or if the output cutoff voltage Vth of inverter 1 is sufficiently small, the control shown in Figure 4 may be used.

[0043] On the other hand, if we want to avoid a situation where a normal 100V AC voltage is not output, we can consider a switching control that first turns on the lithium battery relay 13 and then turns off the auxiliary battery relay 11. In other words, we can consider keeping both relays 11 and 13 on for a certain period of time, and inputting DC voltage to the inverter 1 from both the auxiliary battery 21 and the lithium battery 4.

[0044] However, during the period when both relays 11 and 13 are turned on, the auxiliary battery 21 and alternator 22 are directly connected to the lithium battery 4, as shown in Figure 5. This could potentially cause the lithium battery 4 to become overcharged.

[0045] The longer both relays 11 and 13 are on, the less likely it is that a 100V AC voltage will not be output properly, but there is a possibility of overcharging of the lithium battery 4. On the other hand, the shorter the period both relays 11 and 13 are on, the less likely it is that a 100V AC voltage will not be output properly, but there is a higher possibility of a period of non-functioning 100V AC voltage. Therefore, the appropriate switching timing for relays 11 and 13 will be discussed below.

[0046] Figure 6 is a block diagram showing the schematic configuration of the AC voltage output system 100 according to the second embodiment. In contrast to Figure 1, the positive terminal of the lithium battery 4 is also connected to the system controller 20. The system controller 20 then controls the on / off state of relays 11-13 based on the DC voltage from the auxiliary battery 21 and the DC voltage from the lithium battery 4.

[0047] Figure 7A illustrates an example of the switching timing of relays 11 and 13. When transitioning from state 1 to state 2, the system controller 20 first turns on relay 13 at time t11 (Figure 7A(b)), and then turns off relay 11 at time t12 after the delay time Dt has elapsed (Figure 7A(a)).

[0048] When relay 11 turns off at time t12, the power supply from auxiliary battery 21 (alternator 22) is cut off, and the DC voltage input to inverter 1 begins to decrease (Figure 7A(c)). However, since relay 13 is already on, the DC voltage input to inverter 1 will eventually rise due to the power supply from lithium battery 4.

[0049] Here, if the DC voltage from the lithium battery 4 is sufficiently high, the DC voltage input to the inverter 1 will start to rise without falling below the output cutoff voltage Vth (solid line in Figure 7A(c)).

[0050] On the other hand, if the DC voltage from the lithium battery 4 is insufficient, the DC voltage input to the inverter 1 temporarily falls below the output cutoff voltage Vth, and then begins to rise (dashed line in Figure 7A(c)). In the same figure, during the period from time t13 to t14, the DC voltage input to the inverter 1 falls below the output cutoff voltage Vth, and no 100V AC voltage is output from the inverter 1 during this period (Figure 7A(d)).

[0051] Therefore, in this embodiment, the delay time Dt is variably set according to the difference between the DC voltage from the lithium battery 4 and the DC voltage from the auxiliary battery 21, as described below.

[0052] The system controller 20 calculates the voltage difference Dv based on the following equation (1). Dv = DC voltage from lithium battery 4 - DC voltage from auxiliary battery 21 ...(1) The condition for transitioning from state 1 to state 2 is that the DC voltage from the auxiliary battery 21 falls below a predetermined threshold (for example, 23.5V). Therefore, the second term of the voltage difference Dv may be this threshold (i.e., a fixed value).

[0053] The system controller 20 then sets a delay time Dt according to the voltage difference Dv. The larger the voltage difference Dv, the shorter the delay time Dt should be. The setting method is arbitrary, but for example, as shown in Figure 8, a table defining the relationship between the voltage difference Dv and the delay time Dt may be prepared, and the system controller 20 may set the delay time Dt from the voltage difference Dv based on this table. Alternatively, a relationship formula between the voltage difference Dv and the delay time Dt may be defined, and the system controller 20 may use this formula to calculate the delay time Dt from the voltage difference Dv.

[0054] The delay time Dt is set so that when transitioning from state 1 to state 2, the DC voltage input to inverter 1 does not fall below a predetermined threshold. This predetermined threshold is, for example, the output cutoff voltage Vth, or a higher value.

[0055] When the voltage difference Dv is large, as shown by the solid line in Figure 7A(c), even if the delay time Dt is short, the DC voltage input to inverter 1 will not fall below the output cutoff voltage Vth. Therefore, the period during which both relays 11 and 13 are ON can be shortened, and overcharging of lithium battery 4 can be suppressed.

[0056] On the other hand, when the voltage difference Dv is large, the delay time Dt' is increased, as shown in Figure 7B. This increases the period Dt' during which the DC voltage from the lithium battery 4 is input to the inverter 1 in advance (before the relay 11 turns off), even when the DC voltage from the lithium battery 4 is not large. Therefore, the DC voltage input to the inverter 1 does not fall below the output cutoff voltage Vth. Also, since the output voltage from the lithium battery 4 is not large, overcharging is not much of a problem.

[0057] Thus, according to this embodiment, relays 11 and 13 are switched with a delay time Dt corresponding to the voltage difference Dv between the lithium battery 4 and the auxiliary battery 21. Therefore, during the transition from state 1 to state 2, overcharging of the lithium battery 4 can be suppressed while maintaining a normal output of 100V AC voltage.

[0058] Any or all of the functions of the system controller 20 described herein may be implemented by program. The programs referred to herein may be recorded non-temporarily on a computer-readable recording medium.

[0059] Based on the above description, those skilled in the art may be able to conceive of additional effects and various modifications of the present invention, but the embodiments of the present invention are not limited to the individual embodiments described above. For example, inventions that take only a part of each embodiment, or inventions that combine multiple embodiments, are naturally conceivable. Various additions, modifications, and partial deletions are possible as long as they do not depart from the conceptual idea and spirit of the present invention derived from the contents of the claims and their equivalents.

[0060] For example, what is described herein as a single device (or component, hereinafter the same) (including what is depicted as a single device in the drawings) may be implemented by multiple devices. Conversely, what is described herein as multiple devices (including what is depicted as multiple devices in the drawings) may be implemented by a single device. Alternatively, some or all of the means or functions that are included in one device may be included in another device. Furthermore, a "system" may consist of one device or two or more devices.

[0061] Furthermore, not all matters described herein are mandatory requirements. In particular, matters described herein but not included in the claims can be considered optional additional matters.

[0062] It should also be noted that the applicant is only aware of the prior art inventions described in the "Prior Art Documents" section of this specification, and the present invention is not necessarily intended to solve the problems described in those prior art inventions. The problems that the present invention aims to solve should be determined by considering this specification as a whole. For example, if this specification describes that a certain effect is achieved by a particular configuration, it can also be said that the problem that is the inverse of that predetermined effect is solved. However, this does not necessarily mean that such a particular configuration is an essential requirement. [Explanation of symbols]

[0063] 1 Inverter 2. AC voltage output section 3. Lithium charger 4 Lithium batteries 11. Auxiliary battery relay 12 Charger relay 13 Lithium Battery Relay 14 Pre-charge relay 20 System Controllers 21. Auxiliary battery 22 Alternator 100 AC voltage output system

Claims

1. An inverter that can receive a DC voltage from an onboard battery via a first switch, and a DC voltage from a secondary battery via a second switch, and generates and outputs an AC voltage from the input DC voltage, A charger that charges the secondary battery with the AC voltage from the inverter via a third switch, An AC voltage output device comprising an AC voltage output unit that outputs an AC voltage from the inverter.

2. The AC voltage output device according to claim 1, further comprising a control unit for controlling the on / off state of the first switch, the second switch, and the third switch.

3. The AC voltage output device according to claim 2, wherein the control unit controls the on / off state of the first switch, the second switch, and the third switch based on the DC voltage from the on-board battery.

4. The AC voltage output device according to claim 2 or 3, wherein the control unit controls the on / off state of the first switch and the second switch so that the output of AC voltage from the AC voltage output unit is not interrupted.

5. The control unit, If the DC voltage from the vehicle battery exceeds a first threshold, the first switch is turned on, the second switch is turned off, and the third switch is turned on. The AC voltage output device according to claim 2 or 3, wherein if the DC voltage from the vehicle battery does not exceed a first threshold, the first switch is turned off, the second switch is turned on, and the third switch is turned off.

6. The AC voltage output device according to claim 2 or 3, wherein the control unit turns off the first switch, turns on the second switch, and turns off the third switch when the vehicle on which the AC voltage output device is installed is stopped.

7. The AC voltage output device according to claim 2, wherein the control unit controls the on / off state of the first switch, the second switch, and the third switch based on the DC voltage from the vehicle battery and the DC voltage from the secondary battery.

8. The AC voltage output device according to claim 7, wherein when the DC voltage from the vehicle battery transitions from a state in which it exceeds a first threshold to a state in which it does not exceed a first threshold, the control unit first turns the second switch from off to on, and then, after a delay time corresponding to the difference between the DC voltage from the secondary battery and the DC voltage from the vehicle battery, turns the first switch from on to off.

9. The AC voltage output device according to claim 8, wherein the larger the voltage difference Dv in the following equation, the shorter the delay time. Dv = DC voltage from the secondary battery - DC voltage from the vehicle battery.

10. The AC voltage output device according to claim 8 or 9, wherein the delay time is set so that when the voltage output by the vehicle battery transitions from a state exceeding a first threshold to a state not exceeding the first threshold, the DC voltage input to the inverter does not fall below a second threshold.

11. The inverter will not output an AC voltage properly if the input DC voltage falls below the output cutoff voltage. The AC voltage output device according to claim 10, wherein the second threshold is equal to or higher than the output cutoff voltage.

12. An AC voltage output system comprising the aforementioned secondary battery and an AC voltage output device according to any one of claims 1 to 3, 7 to 9.

13. A vehicle comprising the above-mentioned onboard battery and the AC voltage output system described in claim 12.

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