Power conversion system

Abstract

The power conversion system of the present invention includes a power conversion device and a relay unit. The power conversion device has terminals connected to a high-potential line and a low-potential line. The relay unit is disposed on the low-potential line. The relay unit is disposed between the terminal, a branch point, and the relay unit itself. The relay unit switches between a first state in which the terminal is electrically connected to the branch point via the high-potential line, and a second state in which the terminal is partially electrically connected to the low-potential line between the relay unit and the terminal.

Description

Technical Field

[0001] This disclosure relates to power conversion systems. Background Technology

[0002] Japanese Patent Application Publication No. 2013-90459 discloses a battery electric vehicle. This vehicle includes a battery, an AC / DC converter (power conversion device) for charging the battery, and a controller. The AC / DC converter converts alternating current (AC) power supplied to the vehicle from an external power source into direct current (DC) power and outputs it to the battery. The controller controls the AC / DC converter.

[0003] When a power conversion device is connected to an energy storage device, the terminal voltage (hereinafter also referred to as "terminal voltage") on the energy storage device side of the power conversion device corresponds to the voltage of the energy storage device. If the voltage of the energy storage device is low, the current in the energy storage device increases, potentially leading to overcurrent. On the other hand, if the voltage of the energy storage device is high, there is a possibility that the power conversion efficiency of the power conversion device may be excessively reduced. For these reasons, it is desirable that the voltage of the energy storage device be within a specified reference voltage range corresponding to the type of energy storage device.

[0004] The reference voltage range varies depending on the type of energy storage device, therefore the terminal voltage range needs to correspond to the reference voltage range. For example, for energy storage devices with a high reference voltage range, a power conversion device with a high terminal voltage range is required; for energy storage devices with a low reference voltage range, a power conversion device with a low terminal voltage range is required. Therefore, it is possible to select a suitable power conversion device with a terminal voltage range corresponding to the reference voltage range from a variety of pre-prepared power conversion devices, based on the type of energy storage device. In this case, by mounting a power conversion system including the selected power conversion device in the vehicle, power transmission can be appropriately implemented by allowing the voltage of the energy storage device to vary appropriately within the reference voltage range.

[0005] In recent years, the types of energy storage devices have diversified. Furthermore, the reference voltage range varies depending on the type of energy storage device, thus leading to a diversification of reference voltage ranges. As a result, selecting the appropriate power conversion device each time, as described above, depends on the type of energy storage device installed in the vehicle. Summary of the Invention

[0006] This disclosure provides a power conversion system for appropriately implementing power transmission regardless of the type of energy storage device mounted in a vehicle without requiring the selection of a power conversion device.

[0007] The power conversion system disclosed herein is mounted on a vehicle.

[0008] The power conversion system includes a first power conversion device, a second power conversion device, a first relay unit, and a second relay unit. The first power conversion device has a first terminal pair connected to a first power line pair for connection to a vehicle's connector, and a second terminal pair connected to a second power line pair for connection to the vehicle's energy storage device.

[0009] The second power conversion device has a third terminal pair for connection to a third power line pair for connection to a socket, and a fourth terminal pair for connection to a fourth power line pair branching from the second power line pair.

[0010] The second terminal pair includes: a first terminal for connecting the power line in the second power line pair that is connected to the positive terminal of the energy storage device, i.e., the first high-potential line; and a second terminal for connecting the power line in the second power line pair that is connected to the negative terminal of the energy storage device, i.e., the first low-potential line.

[0011] The fourth terminal pair includes: a third terminal for connecting to a second high-potential line branching from the first high-potential line at the first branch point; and a fourth terminal for connecting to a second low-potential line branching from the first low-potential line at the second branch point.

[0012] The first relay unit is located on the first low potential line.

[0013] The second relay unit is disposed between the second terminal, the third terminal, the first branch point, and the first relay unit.

[0014] The second relay unit switches between a first state in which the third terminal is electrically connected to the first branch point via the second high-potential line, and a second state in which the third terminal is partially electrically connected to the portion between the first relay unit and the second terminal in the first low-potential line.

[0015] By employing the above configuration, the connection state (series / parallel) between the first and second power conversion devices can be appropriately determined based on the states of the first and second relay units. Therefore, power transmission can be appropriately implemented by varying the voltage of the energy storage device within a reference voltage range, regardless of the type of energy storage device installed in the vehicle. Consequently, the time required to select a suitable power conversion device each time based on the type of energy storage device is eliminated. Thus, according to the above configuration, power transmission can be appropriately implemented regardless of the type of energy storage device without the need for selecting a power conversion device.

[0016] The energy storage device may also include a first battery and a second battery.

[0017] The first battery has a positive terminal connected to a first high-potential line.

[0018] The second battery has a negative terminal connected to the first low-potential line. The power conversion system may also include a switching device. The switching device switches whether the first and second batteries are connected in series between the first high-potential line and the first low-potential line, or whether the first and second batteries are connected in parallel between the first high-potential line and the first low-potential line.

[0019] By adopting the above configuration, the connection state of the first and second batteries can be appropriately switched between a series connection state and a parallel connection state based on the maximum output voltage of each power conversion device. Therefore, high voltage withstand capability is not required for each power conversion device, and power transmission can be appropriately implemented.

[0020] According to this disclosure, power transmission can be appropriately implemented regardless of the type of energy storage device installed in the vehicle without the need for selecting a power conversion device. Attached Figure Description

[0021] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same elements, wherein,

[0022] Figure 1 It is an overall configuration diagram of the power system, including the vehicle equipped with the power conversion system involved in the implementation method;

[0023] Figure 2A This is a diagram used to illustrate the vehicle used as a comparative example;

[0024] Figure 2B It is a graph used to illustrate the relationship between battery voltage, battery current, and power conversion efficiency.

[0025] Figure 3 This is a diagram illustrating an example of the flow of electricity during external charging in this embodiment.

[0026] Figure 4 This is a diagram illustrating another example of the flow of electricity during external charging in this embodiment.

[0027] Figure 5A This is a graph used to illustrate the relationship between voltage VB and current of the batteries in the comparative example and the implementation method.

[0028] Figure 5B This is a graph used to illustrate the relationship between voltage VB and current of the batteries in the comparative example and the implementation method.

[0029] Figure 6A This is a flowchart illustrating an example of the process performed by the control device in Modification 1;

[0030] Figure 6B This is a flowchart illustrating an example of the processing performed by the control device in Variation 2;

[0031] Figure 6C This is a flowchart illustrating an example of the processing performed by the control device in Modification 3;

[0032] Figure 6D This is a flowchart illustrating an example of the processing performed by the control device in Variation 4;

[0033] Figure 7 This is a diagram used to explain the structure of the relay unit in Modified Example 5.

[0034] Figure 8A This is a flowchart used to explain the sequence of setting and operation of the object device in Embodiment 2;

[0035] Figure 8B This is a diagram used to illustrate the advantages of embodiment 2;

[0036] Figure 9 This is a diagram illustrating an example of the detailed configuration of the battery and switching circuit in Embodiment 3.

[0037] Figure 10 This is a diagram showing the relationship between the states of the relay unit, power conversion device, first battery, and second battery in Embodiment 2; the target value of the overall output power of the power conversion device; the maximum output voltage of each power conversion device; and the input voltage of the battery; and

[0038] Figure 11 This is a flowchart illustrating an example of determining the order of connection states of the first and second batteries in Embodiment 2. Detailed Implementation

[0039] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Identical or equivalent parts in the drawings will be labeled with the same reference numerals and their descriptions will not be repeated. Embodiments and their variations may also be appropriately combined with each other.

[0040] Implementation Method 1

[0041] Figure 1 This is an overall configuration diagram of the power system of a vehicle equipped with the power conversion system according to Embodiment 1. (Refer to...) Figure 1 The power system 1 includes vehicles 10 and power equipment 20.

[0042] In this example, vehicle 10 is a battery electric vehicle (BEV). Vehicle 10 could also be other types of electric vehicles, such as a plug-in hybrid electric vehicle (PHEV).

[0043] Vehicle 10 includes a battery 105, a voltage sensor 110, a temperature sensor 115, an SMR (System Main Relay) 120, a socket 125, and power conversion devices 130 and 140. Vehicle 10 also includes power line pairs 150, 155, 160, and 170, relay units 180 and 185, temperature sensors 181, 182, and 189, and a control device 190.

[0044] Battery 105 is an example of an electrical storage device that stores electricity for the driving of vehicle 10. Battery 105 has a reference voltage range corresponding to its type. This range is appropriately predetermined through experiments, etc. Voltage sensor 110 detects the voltage VB of battery 105 and outputs its detected value. Temperature sensor 115 detects the temperature TB of battery 105 and outputs its detected value.

[0045] SMR120 is located on power line pair 160 (described later) and is set to the closed state in Embodiment 1. Socket 125 is connected to the power cable of power device 20 and receives power supplied from power device 20 (in this example, AC power).

[0046] The power conversion device 130 is an insulated converter including a transformer, having terminals 132, 134, 136, and 138 and a temperature sensor 139. Terminals 132 and 134 correspond to an example of a "first terminal pair" of this disclosure and are connected to a power line pair 150. The power line pair 150 is connected to a socket 125. Terminals 136 and 138 correspond to an example of a "second terminal pair" of this disclosure and are connected to a power line pair 160. The temperature sensor 139 detects the temperature TC1 of the power conversion device 130 and outputs its detected value.

[0047] The power conversion device 130 operates during power transmission (hereinafter also simply referred to as "power transmission") between the vehicle 10 and the electrical equipment 20. Power transmission can be external charging or external power supply. External charging refers to charging the battery 105 using the power received from the socket 125. External power supply refers to supplying power to external devices (such as the electrical equipment 20 or other household appliances) using the power from the battery 105. During external charging, the power conversion device 130 converts the voltage (terminal voltage V1) between terminals 132 and 134 and outputs the converted voltage (terminal voltage V2A) between terminals 136 and 138. The terminal voltage V1 is, for example, equivalent to the voltage applied from the electrical equipment 20 to the socket 125. On the other hand, during external power supply, the power conversion device 130 converts the terminal voltage V2A and outputs the terminal voltage V1.

[0048] Power line pair 160 is connected to battery 105 and includes a high-potential line 162 and a low-potential line 164. One end of the high-potential line 162 is connected to terminal 136, and the other end is connected to the positive terminal of battery 105. One end of the low-potential line 164 is connected to terminal 138, and the other end is connected to the negative terminal of battery 105.

[0049] The power conversion device 140 is an insulated converter including a transformer, having terminals 142, 144, 146, 148 and a temperature sensor 149. Terminals 142 and 144 correspond to an example of a "third terminal pair" of this disclosure, connected to a power line pair 155. In this example, the power line pair 155 branches from the power line pair 150, but it can also be directly connected to the socket 125. Terminals 146 and 148 correspond to an example of a "fourth terminal pair" of this disclosure, connected to a power line pair 170. The temperature sensor 149 detects the temperature TC2 of the power conversion device 140 and outputs its detected value.

[0050] The power conversion device 140 operates during power transmission, for example, during external charging, converting the voltage between terminals 142 and 144 (terminal voltage V1) and outputting the converted voltage as terminal voltage V2B to terminals 146 and 148. Terminal voltage V2B may differ from terminal voltage V2A, but in the following description, it is assumed to be equal to terminal voltage V2A for ease of understanding. On the other hand, when powered externally, the power conversion device 140 converts terminal voltage V2B and outputs the converted voltage as terminal voltage V1.

[0051] Power line pair 170 branches from power line pair 160, including a high-potential line 172 and a low-potential line 174. High-potential line 172 branches from high-potential line 162 at branch point BP1, with its end connected to terminal 146. Low-potential line 174 branches from low-potential line 164 at branch point BP2, with its end connected to terminal 148.

[0052] Relay section 180 corresponds to a contact relay disposed on low-potential line 164. Relay section 185 is disposed between branch point BP1, terminals 138 and 146, and relay section 180, and includes contacts 186, 187, and 188. Contact 186 is disposed in the portion of low-potential line 164 between relay section 180 and terminal 138 (low-potential line 165). Contacts 187 and 188 are disposed on high-potential line 172 between branch point BP1 and terminal 146. Contact 188 can be connected to either contact 187 or contact 186.

[0053] The state of the relay unit 185 when contacts 188 and 187 are connected is also called "state A". In state A, contacts 187 and 188 constitute the contact relay RL, and terminal 146 is electrically connected to branch point BP1 via high-potential line 172. On the other hand, the state of the relay unit 185 when contacts 188 and 186 are connected is also called "state B". In state B, contacts 186 and 188 constitute the contact relay RL, and terminal 146 is electrically connected to terminal 138 via low-potential line 165. The relay unit 185 switches between state A and state B.

[0054] Temperature sensor 181 is an external air temperature sensor that detects the temperature TE of the external air in vehicle 10 and outputs its detected value. Temperature sensor 182 detects the temperature TR1 of relay section 180 and outputs its detected value. Temperature sensor 189 detects the temperature TR2 of relay section 185 and outputs its detected value. Temperature TR2 is, for example, the temperature of contact relay RL.

[0055] The control device 190 includes a memory and a processor (neither shown). The memory includes read-only memory (ROM) and random access memory (RAM). The ROM stores the program executed by the processor. The RAM functions as working memory. The processor is, for example, a CPU (Central Processing Unit), which performs various arithmetic operations according to the program described above.

[0056] The control device 190 controls various devices of the vehicle 10, such as the SMR 120, power conversion devices 130 and 140, and relay units 180 and 185, based on the detected values ​​of voltage VB and temperatures TB, TE, TC1, TC2, TR1, and TR2. For example, the control device 190 controls the power conversion devices 130 and 140 to supply power to the battery 105 from the power conversion devices 130 and 140 as a whole during external charging (i.e., the power output of the power conversion devices 130 and 140 as a whole during power transmission). Alternatively, the control device 190 controls the power conversion devices 130 and 140 to supply power to the outside of the vehicle 10 from the power conversion devices 130 and 140 as a whole during external power supply (i.e., the power output of the power conversion devices 130 and 140 as a whole during power transmission).

[0057] Voltage sensor 110, temperature sensor 115, power conversion devices 130, 140, power line pairs 150, 155, 160, 170, relay unit 180, 185, temperature sensors 181, 182, 189, and control device 190 form an example of the "power conversion system" of this disclosure.

[0058] Figure 2A and Figure 2B This is a graph used to illustrate the relationship between the comparative example vehicle, voltage VB, and the current and power conversion efficiency of battery 105. (Refer to...) Figure 2A The comparative example vehicle 10A differs from vehicle 10 in that its power conversion system does not include power conversion device 140, power line pairs 155, 170, and relay units 180, 185. Figure 1 The two are different. However, other aspects of the comparative example vehicle 10A are basically the same as those of vehicle 10. In the comparative example, the terminal voltage V2A during external charging corresponds to the output voltage VP of the power conversion device 130. The output voltage VP corresponds to the voltage VB of the battery 105.

[0059] Reference Figure 2B Line 405 represents the relationship between the current IB of battery 105 and the voltage VB (output voltage VP). Line 410 represents the relationship between the power conversion efficiency of power conversion device 130 and the voltage VB.

[0060] The reference voltage range RNG corresponds to the reference voltage range of battery 105. If the voltage VB is lower than the lower limit voltage LV of the reference voltage range RNG, the current in battery 105 may exceed the threshold TH, resulting in overcurrent (line 405). On the other hand, if the voltage VB is higher than the upper limit voltage UV of the reference voltage range RNG, the power conversion efficiency of power conversion device 130 may be excessively reduced and may fall below the specified efficiency eth (line 410). For this reason, the output voltage VP corresponding to voltage VB is limited to a specific allowable range within the reference voltage range RNG.

[0061] Since the reference voltage range RNG varies depending on the type of battery 105, the range of the output voltage VP (terminal voltage V2A) needs to correspond to the reference voltage range RNG. For example, in the comparative example, for a battery 105 with a high reference voltage range RNG, a power conversion device 130 with a high range of output voltage VP is required; for a battery 105 with a low reference voltage range RNG, a power conversion device 130 with a low range of output voltage VP is required. Therefore, it is possible to select a suitable power conversion device 130 with an output voltage VP (terminal voltage V2A) range corresponding to the reference voltage range RNG from various power conversion devices pre-prepared in the factory, etc., according to the type of battery 105. In this case, by mounting a power conversion system including the selected power conversion device on the vehicle 10A, power transmission can be appropriately implemented by appropriately varying the voltage VB within the reference voltage range RNG.

[0062] In recent years, the types of automotive batteries have diversified, and various automotive batteries can be installed in vehicles as batteries 105. Furthermore, since the reference voltage range RNG varies depending on the type of automotive battery, the reference voltage range RNG also varies with the diversity of automotive battery types. As a result, selecting a suitable power conversion device each time, as described above, requires considerable effort depending on the type of automotive battery used as battery 105.

[0063] In contrast, the power conversion system according to Embodiment 1 has a configuration designed to address such a problem. This will be explained below.

[0064] Figure 3 This is a diagram illustrating an example of power flow during external charging in Embodiment 1. (See also...) Figure 3 In this example, relay 180 is in the closed state, and relay 185 is in state A. Figure 1In this case, terminal 146 is connected to branch point BP1 via high-potential line 172, thus power conversion devices 130 and 140 are connected in parallel. As a result, the combined current (large current) of the output current of power conversion device 130 and the output current of power conversion device 140 is supplied to battery 105 through SMR 120 as the overall output current of these power conversion devices. The voltage of the overall output power of these power conversion devices (output voltage VP) is equal to the terminal voltages V2A and V2B, respectively.

[0065] Figure 4 This is a diagram illustrating another example of the flow of electricity during external charging in Embodiment 1. (Refer to...) Figure 4 In this example, relay 180 is in the off state, and relay 185 is in state B. Figure 1 In this case, terminal 146 is connected to terminal 138 via high-potential line 172 and low-potential line 165, thus power conversion devices 130 and 140 are connected in series. As a result, the combined voltage of terminal voltages V2A and V2B is applied to battery 105 as output voltage VP. Furthermore, in this case, the overall output current of power conversion devices 130 and 140 is higher than... Figure 3 The example has a small output current (in one example, it could be...) Figure 3 Half of the examples).

[0066] In implementation 1, for battery 105 with a relatively low voltage VB (reference voltage range RNG), such as Figure 3 As shown, by setting relay 180 to the closed state and relay 185 to state A, power conversion devices 130 and 140 can be connected in parallel. This allows for charging of battery 105 with a large current or for supplying power from battery 105 to external devices. On the other hand, for battery 105 with a relatively high voltage VB (reference voltage range RNG), such as Figure 4 As shown, by setting relay 180 to the off state and relay 185 to state B, power conversion devices 130 and 140 can be connected in series. This suppresses the decrease in power conversion efficiency during battery 105 charging (for example, preventing the power conversion efficiency of each power conversion device from falling below a certain level). Figure 2B The specified efficiency (eth) and the ability to increase the voltage VB to the desired voltage within the reference voltage range RNG, or to apply a high voltage from the battery 105 to an external device through the socket 125.

[0067] Thus, in Embodiment 1, the connection state (series / parallel) between the power conversion devices 130 and 140 can be determined based on the state of the relay units 180 and 185. By appropriately switching this connection state, power transmission such as external charging can be appropriately implemented as described above. That is, in order to appropriately implement power transmission as described above, it is only necessary to install the power conversion system of Embodiment 1 on the vehicle 10 and determine the state of the relay units 180 and 185 based on the voltage of the battery 105. As a result, it is only necessary to prepare the minimum required (e.g., a single) type of power conversion system in the factory or the like, without the need to select a suitable power conversion device each time based on the type of battery 105. Therefore, the types of vehicle power conversion systems prepared in the factory or the like can be reduced to the minimum required. In the above, according to Embodiment 1, power transmission can be appropriately implemented regardless of the type of battery 105 without the need for selecting a power conversion device.

[0068] For example, considering the reference voltage range RNG of battery 105, the connection state (series / parallel) between power conversion devices 130 and 140 can be fixed by operators (e.g., by welding). In one example, if the reference voltage range RNG is known beforehand to be relatively low, the output voltage VP does not need to be high. Therefore, the states of relay sections 180 and 185 can also be fixed so that power conversion devices 130 and 140 are always connected in parallel to charge (or discharge) battery 105 with a high current.

[0069] Preferably, the above connection state is appropriately switched by the control device 190 based on the detected value of voltage VB from voltage sensor 110. In this case, if the detected value of voltage VB is lower than a predetermined reference value, the control device 190... Figure 3 That way, relay section 180 is controlled to the closed state and relay section 185 is controlled to state A. On the other hand, when the detected value of voltage VB is above the reference value, such as Figure 4 In this way, relay section 180 is controlled to the off state and relay section 185 is controlled to state B.

[0070] By configuring the power conversion devices 130 and 140 accordingly, when the detected voltage VB exceeds a reference value, the control device 190 switches the relay 180 from the closed state to the open state, and automatically switches the relay 185 from state A to state B. Therefore, according to this configuration, the series / parallel connection of the power conversion devices 130 and 140 is appropriately switched in response to changes in the voltage VB. For example, when the voltage VB is low, the power conversion devices 130 and 140 are connected in parallel, thus charging the battery 105 with a large current and appropriately shortening the charging time. On the other hand, if external charging is performed and the voltage VB rises, the connection state of these power conversion devices is switched from parallel to series, and the output voltage VP rises. Therefore, the decrease in power conversion efficiency can be suppressed, and the voltage VB can be increased to the desired voltage within the reference voltage range RNG. Thus, according to the control of the control device 190, power transmission such as external charging can be appropriately implemented.

[0071] Figure 5A This is used for the comparative example mentioned above ( Figure 2A The diagram illustrating the relationship between voltage VB (output voltage VP) and current IB in each of Embodiment 1 is shown. (Refer to...) Figure 5A and Figure 5B Line 510 represents the relationship described above in the comparative example. Line 520 represents the case where the power conversion devices 130 and 140 are connected in parallel in Embodiment 1. Figure 3 The above relationship. Line 525 indicates the case where the power conversion devices 130 and 140 are connected in series in Embodiment 1. Figure 4 The above relationship.

[0072] The voltage range rng1 is the permissible range (limited range) of the output voltage VP of the power conversion device 130 in the comparative example. In the comparative example, since the output voltage VP is limited to the voltage range rng1 determined based on the reference voltage range RNG, the voltage VB is also limited to the voltage range rng1. As a result, if the voltage VB is lower than the lower limit voltage V1a, the current IB is limited, and it is impossible to use a current IB larger than the threshold TH1 to charge the battery 105 (line 510). The threshold TH1 is, for example, equivalent to the magnitude of the permissible upper limit current of the power conversion device 130. Furthermore, in the comparative example, when the voltage VB is higher than the upper limit voltage V1b, the power conversion efficiency is excessively reduced, making it difficult to make the voltage VB higher than the upper limit voltage V1b.

[0073] In contrast, in Embodiment 1, the connection state (series / parallel) of the power conversion devices 130 and 140 can be switched. Therefore, the allowable range (limited range) of the output voltage VP from the entire power conversion devices 130 and 140 is expressed as a voltage range rng2 that is wider than voltage range rng1. Voltage range rng2 is determined based on the reference voltage range RNG.

[0074] In Implementation 1, when the detected value of voltage VB is less than the reference value RV (e.g., 500V), such as Figure 3 As shown, relay units 180 and 185 are controlled by connecting power conversion devices 130 and 140 in parallel. Therefore, unlike the comparative example where only power conversion device 130 is allowed to flow through its maximum allowable current, power conversion devices 130 and 140 can each flow through their maximum allowable current. As a result, unlike the comparative example, as long as the output voltage VP is not lower than the lower limit voltage V2a of the voltage range rng2, the maximum allowable current will not flow through each power conversion device. Therefore, battery 105 can be charged (line 520) with a large current (maximum current equal to the threshold value TH2).

[0075] On the other hand, if the detected value of voltage VB exceeds the reference value RV while external charging is in progress, such as Figure 4 As shown, relay units 180 and 185 are controlled by power conversion devices 130 and 140 connected in series. Therefore, in Embodiment 1, even if the output voltage VP exceeds the upper limit voltage V1b, the power conversion efficiency is still within the allowable range, and the output voltage VP can be increased to the upper limit voltage V2b (>V1b) of the voltage range rng2 (line 525). This differs from the comparative example where the power conversion efficiency excessively decreases if the output voltage VP exceeds the upper limit voltage V1b. Therefore, excessive decrease in power conversion efficiency can be suppressed, and the battery 105 with a high reference voltage range RNG can be charged. In this case, for example, the terminal voltages V2A and V2B are lower than the upper limit voltage UV (>V1b). Figure 2B This avoids the power conversion efficiency of each power conversion device being lower than the specified efficiency eth.

[0076] Figure 5B This is a flowchart illustrating an example of the process executed by the control device 190 in Embodiment 1. This flowchart is repeatedly executed during external charging. Hereinafter, each step will be abbreviated as "S".

[0077] Reference Figure 5B The control device 190 determines whether the detected value of voltage VB is less than the reference value RV (S105). If the detected value of voltage VB is less than the reference value RV (yes in S105), the control device 190... Figure 3The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in parallel. Specifically, the control device 190 controls the relay unit 180 to the closed state and controls the relay unit 185 to state A (S110). On the other hand, if the detected value of voltage VB is above the reference value RV (not in S105), the control device 190... Figure 4 The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in series. Specifically, the control device 190 controls the relay unit 180 to the off state and controls the relay unit 185 to state B (S115). After S110 or S115, the processing returns to S105.

[0078] As described above, according to Embodiment 1, power transmission such as external charging can be appropriately implemented regardless of the type of battery 105 without the need for selecting a power conversion device in a factory or the like.

[0079] Variation Example 1

[0080] When in S105 ( Figure 5B If the detected value of voltage VB in the battery is less than the reference value RV, the control device 190 can also control the relay units 180 and 185 based on the detected value of temperature TB of battery 105.

[0081] Figure 6A This is a flowchart illustrating an example of the process performed by control device 190 in Modification 1. This flowchart replaces S110 ( Figure 5B And execute.

[0082] Reference Figure 6A The control device 190 determines whether the detected value of temperature TB is lower than the predetermined value PV1 (S120). When the detected value of temperature TB is lower than the predetermined value PV1 (yes in S120), even if the battery 105 is charged with a large current, it will not overheat. Therefore, as Figure 3 As shown, the control device 190 controls the relay units 180 and 185 in a manner where the power conversion devices 130 and 140 are connected in parallel (S130). On the other hand, when the detected value of temperature TB is above the predetermined value PV1 (not in S120), if the battery 105 is charged with a large current, it may cause the battery 105 to overheat. Therefore, as Figure 4 As shown, the control device 190 controls the relay units 180 and 185 (S135) by connecting the power conversion devices 130 and 140 in series. After S130 or S135, the processing returns to... Figure 5B S105.

[0083] According to Modification 1, when the voltage VB is low and the temperature TB is low, the power conversion devices 130 and 140 are connected in parallel. This allows for charging of the battery 105 with a large current and effective heating of the battery 105. As a result, the time required for power transmission, such as external charging, can be appropriately shortened. On the other hand, when the voltage VB is low and the temperature TB is high, the power conversion devices 130 and 140 are connected in series. This effectively prevents overheating of the battery 105 and enables power transmission.

[0084] Variation Example 2

[0085] When in S105 ( Figure 5B If the detected value of voltage VB is less than the reference value RV, the control device 190 can also control the relay unit 180 and the relay unit 185 based on the detected value of the external air temperature TE.

[0086] Figure 6B This is a flowchart illustrating an example of the process performed by control device 190 in Modification 2. This flowchart replaces S110 ( Figure 5B And execute.

[0087] Reference Figure 6B The control device 190 determines whether the detected value of temperature TE is lower than the predetermined value PV2 (S122). When the detected value of temperature TE is lower than the predetermined value PV2 (yes in S122), there is a tendency for the temperature TB of battery 105 to be low. Therefore, in order to appropriately shorten the power transmission time, the control device 190, such as... Figure 3 The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in parallel (S130). On the other hand, when the detected temperature TE is above the specified value PV2 (not in S122), there is a tendency for the temperature TB to be high. Therefore, the control device 190, in order to prevent the battery 105 from overheating, such as... Figure 4 The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in series (S135). After S130 or S135, the processing returns to... Figure 5B S105.

[0088] According to Modification 2, similar to Modification 1, the time required for power transmission can be appropriately shortened, and overheating of battery 105 can be effectively avoided.

[0089] Variation Example 3

[0090] When in S105 ( Figure 5B If the detected value of voltage VB in the power conversion device 130 is less than the reference value RV, the control device 190 can also control the relay units 180 and 185 according to the detected value of temperature TC1 of the power conversion device 130.

[0091] Figure 6C This is a flowchart illustrating an example of the process performed by control device 190 in Modification 3. This flowchart replaces S110 ( Figure 5B And execute.

[0092] Reference Figure 6C The control device 190 determines whether the detected value of temperature TC1 is lower than the predetermined value PV3 (S124). When the detected value of temperature TC1 is lower than the predetermined value PV3 (yes in S124), even if a large current flows through the battery 105 and the power conversion device 130, the power conversion device 130 will not overheat. Therefore, in order to charge the battery 105 with a large current, the control device 190, such as... Figure 3 The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in parallel (S130). On the other hand, when the detected temperature TC1 is above the specified value PV3 (not in S124), if a large current flows through the battery 105 and the power conversion device 130, it may cause the power conversion device 130 to overheat. Therefore, as Figure 4 As shown, the control device 190 controls the relay units 180 and 185 (S135) by connecting the power conversion devices 130 and 140 in series. After S130 or S135, the processing returns to... Figure 5B S105.

[0093] In the determination process of S124, the detected value of temperature TC1 of power conversion device 130 can also be replaced by the detected value of temperature TC2 of power conversion device 140.

[0094] According to Modification 3, when the voltage VB is low and the temperature TC1 or TC2 is high, the power conversion devices 130 and 140 are connected in series. Therefore, the large current flowing through the power conversion devices 130 and 140, as seen in the example where these power conversion devices are connected in parallel, is not present. Thus, excessive heat generation of these power conversion devices is prevented. As a result, power transmission can be carried out while appropriately protecting the power conversion devices 130 and 140 from overheating.

[0095] Variation Example 4

[0096] When in S105 ( Figure 5B If the detected value of voltage VB in the relay unit is less than the reference value RV, the control device 190 can also control the relay units 180 and 185 according to the detected value of temperature TR1 of the relay unit 180.

[0097] Figure 6DThis is a flowchart illustrating an example of the process performed by control device 190 in Modification 4. This flowchart replaces S110 ( Figure 5B And execute.

[0098] Reference Figure 6D The control device 190 determines whether the detected value of temperature TR1 is lower than the predetermined value PV4 (S126). When the detected value of temperature TR1 is lower than the predetermined value PV4 (yes in S126), even if a large current flows through the battery 105 and the relay unit 180, the relay unit 180 will not overheat. Therefore, in order to charge the battery 105 with a large current, the control device 190, such as... Figure 3 The relay units 180 and 185 are controlled by connecting the power conversion devices 130 and 140 in parallel (S130). On the other hand, when the detected value of temperature TR1 is above the specified value PV4 (not in S126), if a large current flows through the battery 105 and the relay unit 180, it may cause the relay unit 180 to overheat. Therefore, if... Figure 4 As shown, the control device 190 controls the relay units 180 and 185 (S135) by connecting the power conversion devices 130 and 140 in series.

[0099] In the determination process of S126, the detected value of temperature TR1 of relay section 180 can also be replaced by the detected value of temperature TR2 of relay section 185.

[0100] According to Variation 4, when the voltage VB is low and the temperature TR1 or TR2 is high, the power conversion devices 130 and 140 are connected in series. Therefore, the large current flowing through the relay sections 180 and 185, as seen in examples where these power conversion devices are connected in parallel, is avoided. This prevents excessive heat generation in the relay sections 180 and 185. As a result, power transmission can be performed while appropriately protecting the relay sections 180 and 185 from overheating.

[0101] Modified Example 5

[0102] In the above, the relay unit 185 includes contacts 186, 187, and 188 ( Figure 1 However, it can also have other compositions.

[0103] Figure 7 This is a diagram used to explain the configuration of the relay section 185 in Modified Example 5. (Refer to...) Figure 7The relay unit 185 in Modification 5 differs from the relay unit 185 in Embodiment 1 and its Modifications 1 to 4 in that it includes contact relays RL1 and RL2 instead of contacts 186, 187, and 188. State A of the relay unit 185 is defined as the state where contact relay RL1 is closed and contact relay RL2 is open. On the other hand, state B of the relay unit 185 is defined as the state where contact relay RL1 is open and contact relay RL2 is closed. Thus, states A and B can also be... Figure 7 That's certain.

[0104] Implementation Method 2

[0105] The control device 190 of Embodiment 2 differs from the control device 190 of Embodiment 1 in that it can operate only one of the power conversion devices 130 and 140. In other words, the control device 190 operates at least one of the power conversion devices 130 and 140 (hereinafter also referred to as the "target device") and controls the target device in a manner that supplies output power from the target device to the battery 105 or output power from the target device to the outside of the vehicle 10 (output power of the target device during power transmission).

[0106] Figure 8A and Figure 8B These are flowcharts explaining the setup and operation sequence of the object device in Embodiment 2, and diagrams explaining the advantages of Embodiment 2. Hereinafter, the steps will be abbreviated as "S".

[0107] Reference Figure 8A The control device 190 determines whether the target value of the output power is above or below a predetermined value (S103). This target value is appropriately determined based on various conditions such as the specifications of the power equipment 20, the voltage of the battery 105, and the temperature. If the target value is above or below the predetermined value, the control device 190 sets both power conversion devices 130 and 140 as target devices and operates them (S104a). The predetermined value is, for example, the maximum output power of each power conversion device. The maximum output voltage corresponds to the maximum value of the terminal voltages V2A and V2B in the specifications of the power conversion devices 130 and 140. On the other hand, if the target value of the output power is below the predetermined value, the control device 190 sets only one of the power conversion devices 130 and 140 as a target device and operates it (S104b). After that, the process proceeds to S105.

[0108] Reference Figure 8BThe relationship between output power and power conversion efficiency for Embodiment 2 and the comparative example will be explained. In the comparative example, both power conversion devices operate continuously regardless of the target value of the output power. In Embodiment 2, when the target value of the output power is less than a predetermined value, only one power conversion device operates, supplying the target value of output power to its transmission destination. Therefore, in Embodiment 2, power loss during power conversion is reduced compared to the comparative example, especially within the range of low output power. As a result, the power conversion efficiency during power transmission can be appropriately improved based on the output power.

[0109] Implementation Method 3

[0110] The difference between the power system 1 of Embodiment 3 and the power system 1 of Embodiment 1 is that the vehicle 10 further includes a switching circuit connected between the battery 105 and the SMR 120, and the battery 105 includes a first battery and a second battery. Otherwise, the power system 1 of Embodiment 3 is substantially the same as the power system 1 of Embodiments 1 or 2.

[0111] Figure 9 This is a diagram illustrating an example of the detailed configuration of the battery 105 and the switching circuit in Embodiment 3. (Refer to...) Figure 9 Battery 105 includes a first battery 307 and a second battery 309. The first battery 307 has a positive terminal connected to a high-potential line 162 and a negative terminal connected to a switch 314 (described later). The second battery 309 has a positive terminal connected to a switch 312 (described later) and a negative terminal connected to a low-potential line 164.

[0112] The switching circuit 310 includes switches 312, 314, and 316. For example, when switches 312 and 314 are open and switch 316 is closed, the negative terminal of the first battery 307 is connected to the positive terminal of the second battery 309. As a result, the first battery 307 and the second battery 309 are electrically connected in series. On the other hand, when switches 312 and 314 are closed and switch 316 is open, the negative terminal of the first battery 307 is connected to the low-potential line 164, and the positive terminal of the second battery 309 is connected to the high-potential line 162. As a result, the first battery 307 and the second battery 309 are electrically connected in parallel. The state of each switch can be switched by user operation, automatically by the control device 190, or determined by the user through fixing such as soldering.

[0113] In Embodiment 2, switches 312, 314, and 316 of the switching circuit 310 can be used to switch whether the first battery 307 and the second battery 309 are connected in series between the high-potential line 162 and the low-potential line 164 or in parallel between the high-potential line 162 and the low-potential line 164. As a result, by appropriately switching the connection state of the first battery 307 and the second battery 309 between the series connection state and the parallel connection state according to the maximum output voltage of the power conversion devices 130 and 140, power transmission can be appropriately implemented without requiring high voltage withstand capability of each power conversion device (details will be described later).

[0114] Figure 10 This is a diagram showing the relationship between the states of the relay units 180 and 185, the power conversion devices 130 and 140, the first battery 307 and the second battery 309 in Embodiment 2, the target value of the overall output power of the power conversion devices 130 and 140, the maximum output voltage of each power conversion device, and the input voltage of the battery 305.

[0115] Reference Figure 10 When the maximum output voltage of each power conversion device is above a specified voltage (Va in this example), the switching circuit 310 is used to connect the first battery 307 and the second battery 309 in series. Conversely, when the power conversion devices 130 and 140 are connected in parallel and the maximum output voltage is less than a specified voltage (Vb in this example), the switching circuit 310 is used to connect the first battery 307 and the second battery 309 in parallel. The connection state of the first battery 307 and the second battery 309 is determined as described above when the target output power of the power conversion devices 130 and 140 as a whole is above the specified value (e.g., Wa) or when the target value is less than the specified value (e.g., Wb). In this example, Va = 800 [V], Vb = 400 [V], and Wa = 2 × Wb [W]. Furthermore, when the power conversion devices 130 and 140 are connected in series, the connection state of the first battery 307 and the second battery 309 becomes a series connection state even when the maximum output voltage is less than the specified voltage.

[0116] Sometimes, the power conversion devices 130 and 140, which are the target devices, are connected in parallel, and the first battery 307 and the second battery 309 are connected in series. In this case, in order to charge the battery 105, the output voltage VP of each power conversion device needs to be greater than the sum of the voltages of the first battery 307 and the second battery 309. This requires high voltage withstand capability for each power conversion device.

[0117] Therefore, it is possible to charge the battery 105 by switching the relay units 180 and 185 and connecting the power conversion devices 130 and 140 in series, as in Embodiment 1. However, in this case, the output power (charging power to the battery 105) from the entire power conversion devices is reduced.

[0118] In contrast, in Embodiment 2, the power conversion devices 130 and 140 can be operated with the power conversion devices 130 and 140 connected in parallel and the first battery 307 and the second battery 309 connected in parallel using the switching circuit 310. In this case, to charge the battery 105, the output voltage VP does not need to be greater than the sum mentioned above; it only needs to be greater than the individual voltages of the first battery 307 and the second battery 309. Furthermore, since the power conversion devices 130 and 140 operate in parallel, the output power is twice that supplied from a single power conversion device, and it does not decrease as described above. Therefore, the battery 105 can be charged without the high withstand voltage of the power conversion devices 130 and 140 or the decrease in output power. For example, even if the maximum output voltage of each power conversion device is Vb (< Va), the output power of Wa (> Wb) can be supplied to the battery 105 as charging power.

[0119] Figure 11 This is a flowchart illustrating an example of determining the order of connection states of the first battery 307 and the second battery 309 in Embodiment 2. (Refer to...) Figure 11 When the maximum output voltage of each power conversion device is above a specified voltage (yes in S101), the state of each switch in the switching circuit 310 is determined by connecting the first battery 307 and the second battery 309 in series (S102a). Conversely, when the maximum output voltage is below the specified voltage (no in S101), the state of each switch in the switching circuit 310 is determined by connecting the first battery 307 and the second battery 309 in parallel (S102b). After S102a or S102b, the process ends. Then, for example, begin... Figure 5B or Figure 8A The processing of flowcharts.

[0120] As described above, in Embodiment 3, the switching circuit 310 can be used to switch the connection state (series / parallel) of the first battery 307 and the second battery 309. Therefore, power transmission can be appropriately implemented without requiring high voltage withstand capability of each power conversion device.

[0121] Other variations

[0122] The power conversion devices 130 and 140 are insulated type converters as described above, but they can also be replaced by converters such as current reversible type boost chopper circuits.

[0123] All points in the embodiments disclosed herein should be considered illustrative and not intended to limit the invention. The scope of the invention is not limited by the foregoing description, but is defined by the technical solutions and is intended to include equivalents and all modifications within that scope.

Claims

1. A power conversion system, mounted on a vehicle, characterized in that, The power conversion system includes: The first power conversion device has a first terminal pair connected to a first power line pair for connection to a plug of the vehicle, and a second terminal pair connected to a second power line pair for connection to a battery storage device of the vehicle. and The second power conversion device has a third terminal pair for connecting to a third power line pair connected to the socket, and a fourth terminal pair for connecting to a fourth power line pair branching from the second power line pair. The second terminal pair includes: a first terminal for connecting the power line in the second power line pair that is connected to the positive terminal of the energy storage device, i.e., the first high-potential line; and a second terminal for connecting the power line in the second power line pair that is connected to the negative terminal of the energy storage device, i.e., the first low-potential line. The fourth terminal pair includes: a third terminal for connecting to a second high-potential line branching from the first high-potential line at a first branch point; and a fourth terminal for connecting to a second low-potential line branching from the first low-potential line at a second branch point. The power conversion system also features: A first relay section is disposed on the first low-potential line; and The second relay unit is disposed between the second terminal, the third terminal, the first branch point, and the first relay unit. The second relay unit switches between a first state in which the third terminal is electrically connected to the first branch point via the second high-potential line, and a second state in which the third terminal is partially electrically connected to the portion between the first relay unit and the second terminal in the first low-potential line.

2. The power conversion system according to claim 1, characterized in that, The power conversion system also features: The voltage sensor outputs the voltage detection value of the energy storage device; and The control device controls the first relay unit and the second relay unit based on the voltage detection value. The control device is configured as follows: If the detected voltage value is lower than the reference value, the first relay unit is controlled to be in the closed state, and the second relay unit is controlled to be in the first state. When the voltage detection value is above the reference value, the first relay unit is controlled to be in the off state, and the second relay unit is controlled to be in the second state.

3. The power conversion system according to claim 2, characterized in that, The power conversion system also includes a first temperature sensor that outputs the temperature detection value of the energy storage device. When the voltage detection value is lower than the reference value, and the temperature detection value output from the first temperature sensor is higher than the first predetermined value, the control device controls the first relay unit to the disconnected state and controls the second relay unit to the second state.

4. The power conversion system according to claim 2, characterized in that, The power conversion system also includes a second temperature sensor that outputs the temperature of the outside air in the vehicle. When the voltage detection value is lower than the reference value, and the temperature detection value output from the second temperature sensor is higher than the second predetermined value, the control device controls the first relay unit to the disconnected state and controls the second relay unit to the second state.

5. The power conversion system according to claim 2, characterized in that, The power conversion system also includes a third temperature sensor that outputs the temperature detection value of the first power conversion device or the second power conversion device. When the voltage detection value is lower than the reference value, and the temperature detection value output from the third temperature sensor is higher than the third predetermined value, the control device controls the first relay unit to the disconnected state and controls the second relay unit to the second state.

6. The power conversion system according to claim 1, characterized in that, The energy storage device includes: a first battery having a positive terminal connected to the first high-potential line; and a second battery having a negative terminal connected to the first low-potential line. The power conversion system also includes a switching device that switches between connecting the first battery and the second battery in series between the first high-potential line and the first low-potential line, or connecting the first battery and the second battery in parallel between the first high-potential line and the first low-potential line.

Images