Electric vehicle systems and electric vehicles equipped therewith

Abstract

To provide an electric vehicle driven by a secondary battery which suppresses useless energy consumption and shortens charge time to improve usability.SOLUTION: An electric vehicle system comprises: a fuel battery 31 and a secondary battery 22; an external charging interface 21 which charges the secondary battery 22 from an external power source; a secondary battery temperature acquisition part which acquires temperature of the secondary battery 22; a secondary battery temperature regulating system 25 which regulates temperature of the secondary battery 22; and a controller 51 which controls, when temperature of the secondary battery is out of a prescribed condition at the time of charging and when the fuel battery is operating, to continue operation of the fuel battery 31 to supply the secondary temperature regulating system 25 with power.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to an electric vehicle equipped with both a fuel cell and a secondary battery.

Background Art

[0002] Generally, the drive secondary battery provided in an electric vehicle can be charged by an external power source. Mainly lithium-ion batteries are used for the secondary battery. Since the capacity is large, the charging time tends to be long, and the demand from users for shortening it is strong.

[0003] When the temperature of the secondary battery becomes excessively low during charging, acceleration of deterioration occurs and the input / output possible power decreases. On the other hand, acceleration of deterioration also occurs when the temperature of the secondary battery becomes excessively high, such as during rapid charging. Also, especially at high temperatures, there is a risk that the solvent, separator, etc. will denature, and the input / output possible power is limited from the viewpoint of safety. In any case, when the input / output possible power decreases, the charging time will be lengthened accordingly. To prevent this, some electric vehicles are proposed that are equipped with a temperature adjustment system that operates a heater or cooler for heating the secondary battery to adjust the temperature to a suitable temperature at which a suitable output can be exhibited.

[0004] Among this temperature adjustment system, the generally used normal temperature adjustment system has a configuration as shown in FIG. 5. Taking an electric vehicle that charges the secondary battery 22 with a fuel cell 31 and an external power source (external charging interface 21) and drives a motor 41 with the secondary battery 22 as an example. The secondary battery 22 and the fuel cell 31 receive instructions from a control unit (referred to as "ECU" in the figure) 51. During the charging of the secondary battery 22 by the external power source 21, the control unit 51 continuously monitors the temperature of the secondary battery 22, and when the temperature becomes below a predetermined temperature or above a predetermined temperature, it supplies power from the secondary battery 22 itself to the secondary battery temperature adjustment system 25 to heat the secondary battery 22 itself with a heater 26 or, conversely, cool the secondary battery 22 itself with a cooler 27 to keep the temperature within a predetermined range and prevent a decrease in the input / output possible power.

[0005] On the other hand, some electric vehicles are being offered that are equipped with a fuel cell (FC) along with a secondary battery, as shown in Patent Document 1. At the time of this application, the general recommended operating temperature for a fuel cell is about 80°C. However, fuel cells do not operate continuously; when the vehicle is parked and the secondary battery is being charged by an external power source, or when the electric vehicle is running solely on the secondary battery, the fuel cell is stopped to reduce fuel consumption. In particular, if the operation of the fuel cell is stopped while charging by an external power source, the temperature of the fuel cell will gradually decrease. If the temperature of the fuel cell drops too low, it will need to be warmed up again before the next operation. Also, since fuel cells generate water when they operate, if the generated water remains in the gas flow path in a sub-zero environment, it may freeze and block the gas flow path. For this reason, when stopping the fuel cell, it may be necessary to discharge the water remaining in the path along with the fuel gas remaining inside using a blower or similar device. This discharge also consumes additional energy.

[0006] Furthermore, when starting a fuel cell in a sub-zero environment, it is determined whether the gas path is frozen, and if it is determined to be frozen, a heating process is performed to thaw it. Heating processes include methods such as generating electricity by lowering the cathode gas-air-fuel ratio of the fuel cell to generate power, so that the heat output of the fuel cell exceeds the heat output, thereby warming the system, or heating with an external heater. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-181757 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, in conventional electric vehicle systems, when the secondary battery temperature falls outside a predetermined range during charging, the secondary battery itself supplies power to operate temperature control systems such as heaters and coolers. This consumes some of the stored power during charging, which prolongs the charging time.

[0009] Furthermore, when charging externally, the vehicle's power is temporarily turned off, and the fuel cell operation is also stopped, causing the fuel cell temperature to drop to ambient temperature. As a result, the fuel cell needs to be warmed up before the vehicle can be driven again, and the electricity stored in the secondary battery is consumed for this warming process.

[0010] Furthermore, in sub-zero temperatures, when the vehicle is powered off, residual generated water and fuel gas must be exhausted to prevent the fuel cell from freezing, and this exhaust system consumes power stored in the secondary battery. On the other hand, when starting the vehicle in sub-zero temperatures, if it is determined that the gas path to the fuel cell is frozen, not only the normal fuel cell warm-up process but also a heating process to thaw the gas path is required. Such a heating process consumes even more power from the secondary battery.

[0011] Therefore, the objective of this invention is to improve convenience in electric vehicles powered by secondary batteries by suppressing unnecessary energy consumption and shortening charging time. [Means for solving the problem]

[0012] This invention is Fuel cells and secondary batteries installed in vehicles, An external charging interface for charging the secondary battery from an external power source, A secondary battery temperature acquisition unit that acquires the temperature of the secondary battery, A secondary battery temperature control system for adjusting the temperature of the secondary battery, When charging is performed, if the temperature of the secondary battery is outside of predetermined conditions and the fuel cell is in operation, a control unit controls the fuel cell to continue operating and supply power to the secondary battery temperature control system. The above problems were solved by an electric vehicle system having [this feature].

[0013] The secondary battery temperature control system should preferably include both a heater for heating and a cooler for cooling. That is, if the fuel cell is operating when charging begins, the fuel cell can continue to operate without the need for a heating process. By operating the secondary battery temperature control system with power supplied from this fuel cell, energy consumption from the secondary battery being charged is suppressed, preventing prolonged charging times, and allowing the secondary battery to be continuously adjusted to an appropriate temperature range. At this time, the power to the operating fuel cell does not need to be turned off, and it is sufficient to continue operating it as is, thus avoiding the consumption of energy required to heat up the fuel cell itself.

[0014] Furthermore, the electric vehicle system according to this invention is The system further includes a fuel cell temperature acquisition unit that acquires the temperature of the fuel cell, The control unit, When performing the aforementioned charging, if the temperature of the secondary battery is outside of predetermined conditions and the fuel cell is not operating, and the temperature of the fuel cell is above a predetermined value, the system controls the system to restart the fuel cell and supply power to the secondary battery temperature control system. The configuration can be adopted.

[0015] Even if the fuel cell is not operating during the aforementioned charging process, if it has not been a long time since the fuel cell ceased operation, it often maintains a reasonable temperature. If this temperature is above a predetermined value, the energy consumption required to raise the temperature necessary for fuel cell operation is allowed, and the secondary battery temperature control system is activated by power supplied from the fuel cell. This results in overall energy efficiency, reduces the consumption of power charged to the secondary battery, and avoids prolonged charging times.

[0016] Furthermore, the electric vehicle system according to this invention The control unit When performing the charging, when the temperature of the secondary battery is outside a predetermined condition, when the fuel cell is not in operation, and when the temperature of the fuel cell is not above a predetermined value, if at least any one of the following conditions (1) to (3) is satisfied, the fuel cell is restarted and controlled to supply power to the secondary battery temperature adjustment system. A configuration can be adopted. (1) The voltage of the fuel cell is not less than a predetermined value. (2) The degree of deterioration of the fuel cell is not more than a predetermined value. (3) The estimated expected charging time from the start to the end of charging of the secondary battery is not less than a predetermined value.

[0017] That is, even when the temperature of the fuel cell is decreasing, if the voltage of the fuel cell is still high enough and fuel supply for operation can be energy-saving, or if the fuel cell is not deteriorated and can exhibit sufficient output, or if the assumed prediction time until charging is short, it may be more preferable to operate the secondary battery temperature adjustment system by the fuel cell rather than by the secondary battery itself from the viewpoints of energy efficiency and other comprehensiveness. When any of these conditions is satisfied, it is better to prevent the charging time from being prolonged by driving the secondary battery temperature adjustment system with power supplied from the fuel cell.

Advantages of the Invention

[0018] In an electric vehicle equipped with the electric vehicle system according to this invention, when charging the secondary battery, the fuel cell under appropriate conditions supplies the power required for temperature adjustment of the secondary battery, suppressing the energy required for warming up the fuel cell and shortening the time required for charging the secondary battery, thereby saving energy and improving convenience.

Brief Description of the Drawings

[0019] [Figure 1]Schematic diagram of an embodiment of an electric vehicle system incorporated in an electric vehicle according to this invention [Figure 2] Functional block diagram of an embodiment of an electric vehicle system according to this invention [Figure 3] Functional flow example diagram of an electric vehicle system according to this invention [Figure 4] Second functional flow example diagram of an electric vehicle system according to this invention [Figure 5] Functional block diagram which is an embodiment of a conventional electric vehicle system

Embodiments for Carrying Out the Invention

[0020] Embodiments of this invention will be described using the example of the electric vehicle shown in FIG. 1. This invention is an electric vehicle system mounted on an electric vehicle 11 having a secondary battery 22 and a fuel cell 31 (denoted as "FC31" in the figure). The electric vehicle 11 is a plug-in hybrid vehicle (PHEV) having an external charging interface 21 so that the secondary battery 22 can be charged not only by the fuel cell 31 but also by external charging from an external power source. Also, although not shown, the secondary battery 22 may also be capable of external power supply to the outside. Here, an embodiment will be described by taking as an example the case where the electric vehicle 11 travels by supplying power from the secondary battery 22 to drive the motor 41.

[0021] Regarding the embodiment example of FIG. 1 of the electric vehicle system according to this invention, a more detailed functional block diagram is shown in FIG. 2. In the electric vehicle system according to this invention, power (I1) is supplied from the external charging interface 21 to the secondary battery 22 for charging. Also, the power (I2) generated by the fuel cell 31 is also appropriately supplied to the secondary battery 22 for charging. The motor 41 is driven by the power (I3) stored in these secondary batteries to make the electric vehicle 11 travel.

[0022] The electric vehicle system according to this invention has a secondary battery temperature control system 25 that adjusts (H / C) the temperature of the secondary battery 22. It is desirable that the secondary battery temperature control system 25 has both a heater 26 that heats the secondary battery 22 and a cooler 27 that cools the secondary battery 22. This is to prevent the input / output power of the secondary battery 22 from decreasing too much by cooling when the temperature is higher than the appropriate temperature range and heating when the temperature is lower than the appropriate temperature range.

[0023] The electric vehicle system according to this invention utilizes a secondary battery temperature control system 25 and includes a secondary battery temperature acquisition unit (not shown) that acquires the temperature (t1) of the secondary battery 22. The secondary battery temperature acquisition unit is attached to a predetermined location that affects the electrode reaction of the secondary battery 22 and outputs the temperature.

[0024] The electric vehicle system according to this invention preferably has an information acquisition unit for acquiring information about the fuel cell 31. Specifically, it is preferable to have a fuel cell operation acquisition unit that acquires operation information (TF) indicating whether or not the fuel cell 31 is in operation, a fuel cell temperature acquisition unit that acquires temperature (t2), a fuel cell voltage acquisition unit that acquires voltage (e2), and a fuel cell degradation degree acquisition unit that acquires the degradation degree (D) of the fuel cell. As means of acquisition, general information acquisition means such as directly acquiring information from a voltmeter or thermometer, or calculating from those values, can be used. For example, operation information (TF) can be determined not only by voltage, but also by the presence or absence of load (current) and the presence or absence of movement of auxiliary equipment such as a compressor (i.e., the presence or absence of air (fuel) introduction).

[0025] The electric vehicle system according to this invention has a control unit 51 that performs electronic control of a secondary battery system and a fuel cell system. In this embodiment, the control unit 51 has a PHEV-ECU 52 that is responsible for the control system of the secondary battery 22 and an FC-ECU 53 that is responsible for the control system of the fuel cell 31. Here, ECU stands for Electronic Control Unit. These have a semiconductor computing device and memory, and receive output requests (c1, c2) from operating devices 50 such as a steering wheel, brakes, and accelerator, and send data and commands to each part including the secondary battery 22 and fuel cell 31, and acquire data from each part.

[0026] The PHEV-ECU52 sends a power supply request c3 to the secondary battery 22 at the necessary timing, and the secondary battery 22 supplies power to the motor 41, the secondary battery temperature control system 25, and, although not shown, an external power supply interface for external power supply, according to the instructions. Meanwhile, the PHEV-ECU52 acquires the temperature (t1), voltage (e1), and state of charge (SOC) of the secondary battery 22. The temperature (t1) is obtained from the secondary battery temperature acquisition unit described above. The voltage (e1) is obtained from the voltmeter on the secondary battery 22. The state of charge (SOC) can be calculated using the voltage (e1) acquired from the secondary battery 22, by referring to the voltage at full charge and the charge / discharge characteristics of the secondary battery 22, which are registered in advance for use.

[0027] The FC-ECU 53 sends a power generation request (c4) to the fuel cell 31 at the necessary timing, and the fuel cell 31 generates power according to the instruction. This power generation can be used to supply power to the secondary battery 22 (I2), to the secondary battery temperature control system 25 (I5) described later, and to supply other necessary power as appropriate. Meanwhile, the FC-ECU 53 obtains information from the fuel cell 31 such as the temperature (t2) of the fuel cell 31, whether the fuel cell 31 is operating or not (TF), the voltage of the fuel cell 31 (e2), and the degree of degradation (D). Alternatively, the FC-ECU 53 may calculate the degree of degradation (D) from the information obtained. When calculating the degree of degradation (D), for example, the following configuration can be used, which takes advantage of the fact that the voltage decreases when the fuel cell deteriorates. The voltage value at a certain load (generated current) in the initial state is obtained in advance and recorded in a storage means (not shown). Then, the voltage value at the same load (generated current) is obtained and the difference from the voltage in the initial state is calculated. The decrease in this difference can be taken as the degree of degradation (D).

[0028] In the electric vehicle system according to this invention, the control unit 51, which is either or both of the PHEV-ECU 52 and EC-ECU 53, sends target set temperatures (t11, t12) for suitably adjusting the temperature of the secondary battery 22 to the secondary battery temperature adjustment system 25. When charging the secondary battery 22 (I1), the secondary battery 22 and the fuel cell 31 each provide the power (I5, I6) to operate the secondary battery temperature adjustment system 25 that adjusts the temperature of the secondary battery 22, under the following conditions.

[0029] First, when the electric vehicle 11 is ignitioned and in motion (driving or stopped), the power to operate the secondary battery temperature control system 25 is supplied by the secondary battery 22. At this time, the temperature (t3) of the secondary battery temperature control system 25 itself is also transmitted to the PHEV-ECU 52, which adjusts it to an appropriate temperature. This temperature control system, which operates using power supplied from the secondary battery 22, is referred to as the "normal temperature control system."

[0030] Next, the process when the electric vehicle 11 is turned off will be explained using the example flow shown in Figure 3. First, when the key is turned off (S101), a waiting period is set to determine whether or not to perform external charging (S102). If external charging is not performed (S102 → No), the fuel cell 31 is stopped as is (S103). If external charging is performed during the predetermined waiting period after the key is turned off (S102 → Yes → S105), the control unit 51 (PHEV-ECU 52) obtains the temperature t1 of the secondary battery 22 and makes a determination. If the temperature of the secondary battery 22 is between the lower limit a℃ and the upper limit b℃ (S105 → Yes), there is no need to adjust the temperature, so external charging is continued as is (S106). The temperature ranges of a and b depend on the type of secondary battery installed, but are preferably 0℃ to 50℃, and more preferably 10℃ to 40℃.

[0031] Until external charging is complete (S121→No→S105), the temperature is checked periodically. This is because the output power will decrease if the temperature is too low or too high. The temperature may exceed the upper limit not only when the ambient temperature is high, but also due to the heat generated during charging. On the other hand, if the ambient temperature is too low, the temperature may still fall below the lower limit even with the heat generated during charging. For this reason, the temperature is checked periodically during charging. However, at this stage, the secondary battery temperature control system 25 by the fuel cell 31 is not operating (S122→No), and there is little benefit in keeping the fuel cell 31 running, so the fuel cell 31 is stopped (S123), and the subsequent temperature check cycle is repeated (S105). Alternatively, instead of S122 and S123, it may be possible to check whether a predetermined time has elapsed since the key was turned off, and if the predetermined time has not elapsed, the operation of the fuel cell 31 may be continued.

[0032] If the temperature t1 of the secondary battery 22 is outside the range a≦t1≦b (S105→No), the secondary battery temperature control system 25 must be activated. At this time, the control unit 51 (FC-ECU 53) determines whether or not the fuel cell 31 is operating (TF) (S111). This can be done not only for the first S105 determination immediately after charging, but also for any subsequent S105 determinations after charging has started. If the fuel cell 31 is still operating at this stage (S111→Yes), the operation of the fuel cell 31 continues, and power (t5) is supplied from the fuel cell 31 to the secondary battery temperature control system 25 (S112). This allows the temperature of the secondary battery 22 to be adjusted to an appropriate temperature range by the heater 26 or cooler 27 without the fuel cell 31 consuming energy to heat up in order to operate, and without consuming the power being charged from the secondary battery 22 to be charged, thereby prolonging the charging time. Until external charging is complete, this temperature check is repeated, and as long as the temperature of the secondary battery 22 is outside the above range (S105 → No), the operation of the fuel cell 31 continues (S111 → Yes → S112). When the temperature of the secondary battery 22 returns to the above range (S105 → Yes), the operation of the fuel cell 31 is terminated (S122 → No → S123) and charging continues (S105 → S106). When external charging is complete (S121 → Yes), if the fuel cell 31 is operating (TF), it is stopped (S131 → Yes → S132), otherwise (S131 → No), the control unit 51 terminates the series of flows (S133).

[0033] Furthermore, in the electric vehicle system according to this invention, as an application of the above flow, when the temperature t1 of the secondary battery 22 is outside the above range during charging and the fuel cell 31 is not operating (S111→No), it may be preferable to start the secondary battery temperature control system 25 with power from the fuel cell 31 (I5) in accordance with the flow in Figure 3, rather than using the normal temperature control system which starts the secondary battery temperature control system 25 with power from the secondary battery 22 (I6). The flow in that case will be explained using Figure 4.

[0034] Even if the fuel cell 31 is not operating (TF), if the temperature t2 of the fuel cell 31 is above a predetermined temperature c°C, the energy required to raise the temperature of the fuel cell 31 to its operating temperature can be kept to an acceptable level. For this reason, if the temperature t2 of the fuel cell 31 is above c°C, the fuel cell 31 is restarted and power is supplied to the secondary battery temperature control system 25 from the fuel cell 31 instead of the secondary battery 22 (S152). By doing this, the power of the charging secondary battery 22 is not consumed for temperature control, the charging time is not extended, and the energy required to raise the temperature of the fuel cell 31 is kept to a minimum, thus shortening the charging time in an energy-saving manner. From this point onward, the same flow as above is followed until the completion of external charging (S121) while the fuel cell 31 is operating. Note that this temperature c°C depends on the fuel cell used, but for current general fuel cells, it is preferable to set it to around 40°C or higher.

[0035] Furthermore, as a further application of the above flow, the electric vehicle system according to this invention may be preferable to restart the fuel cell 31 and operate the secondary battery temperature control system 25 with power from the fuel cell 31 (I5) rather than operating the secondary battery temperature control system 25 with power from the secondary battery 22 (I6), even when the fuel cell 31 is not operating (S111 → No) and the temperature of the fuel cell 31 is below c℃ (S151 → No), as this allows for the enjoyment of the benefit of reduced charging time with less burden. Such conditions include satisfying at least one of the following (1) to (3) (S160, S161 to S163). The condition may be considered satisfied if at least one condition is satisfied, or if any multiple of the conditions from (1) to (3) are satisfied simultaneously.

[0036] One of the conditions (1) above is whether the voltage (e2) of the fuel cell 31 is equal to or greater than a predetermined value x (V) (S161). This is because even if the temperature of the fuel cell 31 has dropped, if the voltage is above a certain level, there is still fuel remaining, and it becomes possible to supply power to the secondary battery temperature control system 25 while sufficiently saving the energy required for restart.

[0037] Condition (2) above is whether the degradation level (D) of the fuel cell 31 is below a predetermined value G (S162). This is because the more times the fuel cell is started (i.e., the more hydrogen / air gas is introduced and exhausted), the more the fuel cell itself deteriorates. At this stage, the fuel cell has already stopped, so restarting it will increase the number of starts. If the degradation level (D) is high, it is necessary to prioritize fuel cell protection even at the expense of the benefits of this proposal, such as shortening the charging time. On the other hand, if the degradation level (D) is below the predetermined value G and the deterioration has not progressed so much, it will not require excessive energy to restart, and it will be possible to supply power to the secondary battery temperature control system 25.

[0038] Condition (3) above is whether the estimated expected charging time of the fuel cell 31 at that stage is equal to or greater than a predetermined time N (min). The expected charging time is the estimated time until charging is complete, and the control unit 51 should calculate and determine this from the state of charge (SOC) of the secondary battery 22 and the amount of power supplied. If the expected charging time is short, there is a high possibility that the fuel cell will be fully charged immediately even if it is restarted, resulting in wasted energy, so it is generally preferable to use the temperature control system. On the other hand, if the expected charging time is sufficiently long, it is considered that even if the fuel cell is restarted and charged, the utilization will be sufficient to offset the disadvantage of increasing the number of fuel cell startups by one.

[0039] If any or more of the above conditions (1) to (3) are not met (S160 → No), the normal temperature control system is executed, which operates the secondary battery temperature control system 25 using power from the secondary battery 22 (I6) (S171). This is because restarting the fuel cell 31 from that state would result in unacceptable energy loss. Conversely, if any or more of these conditions are met (S160 → Yes), the benefit of reduced charging time obtained by operating the fuel cell 31 becomes greater (S152). [Explanation of Symbols]

[0040] 11 Electric Vehicles 21 External charging interface 22 Secondary battery 25. Secondary battery temperature control system 26 Heater 27 Cooler 31 Fuel Cell 41 Motor 50 Operating device 51 Control Unit 52 PHEV-ECU 53 FC-ECU

Claims

1. Fuel cells and secondary batteries installed in vehicles, An external charging interface for charging the secondary battery from an external power source, A secondary battery temperature acquisition unit that acquires the temperature of the secondary battery, A secondary battery temperature control system for adjusting the temperature of the secondary battery, When charging is performed, if the temperature of the secondary battery is outside of predetermined conditions and the fuel cell is in operation, a control unit controls the fuel cell to continue operating and supply power to the secondary battery temperature control system. An electric vehicle system having

2. The system further includes a fuel cell temperature acquisition unit that acquires the temperature of the fuel cell, The control unit, When performing the aforementioned charging, if the temperature of the secondary battery is outside of predetermined conditions and the fuel cell is not operating, and the temperature of the fuel cell is above a predetermined value, the system controls the system to restart the fuel cell and supply power to the secondary battery temperature control system. The electric vehicle system according to claim 1.

3. In the electric vehicle system according to claim 2, The control unit, An electric vehicle system that, when performing the aforementioned charging, controls the system to restart the fuel cell and supply power to the secondary battery temperature control system if the temperature of the secondary battery is outside of predetermined conditions, the fuel cell is not operating, the temperature of the fuel cell is not above a predetermined value, and at least one of the following conditions (1) to (3) is met. (1) The voltage of the fuel cell is above a predetermined value. (2) The degree of degradation of the fuel cell is below a predetermined value. (3) The estimated expected charging time from the start to the end of charging of the secondary battery is greater than or equal to a predetermined value.

4. An electric vehicle equipped with the electric vehicle system according to any one of claims 1 to 3.

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