Electric power system, startup control method for turbine engine, and vehicle

Abstract

According to the present invention, if a first battery, which is a power source of a high voltage system, is normal when starting a turbine engine, a turbine control device for controlling the turbine generator assists with starting the turbine engine by driving a power generation inverter by using the power of the first battery, and if the first battery is abnormal, the turbine control device electrically disconnects the first battery and drive inverter and assists with starting the turbine engine by driving the power generation inverter by using power from a second battery, which is a power source of a low voltage system. The amount of power consumption when assisting with starting the turbine engine by using the power of the second battery is made smaller than the amount of power consumption when assisting with starting the turbine engine by using the power of the first battery.

Description

Power system, turbine engine start control method, and vehicle

[0001] The present disclosure relates to an electric power system, a turbine engine starting control method, and a vehicle.

[0002] In recent years, electric vehicles have come into practical use. Electric vehicles use electric power stored in a high-voltage battery to rotate a drive motor, which then drives using the drive torque output from the drive motor. For such electric vehicles, a turbine generator using a generator driven by a turbine engine is known as a range extender that generates electric power to charge the high-voltage battery and extends the cruising range of the electric vehicle.

[0003] The turbine engine includes a gas turbine, a combustor that supplies combustion gas to the gas turbine, a compressor that supplies compressed gas to the combustor, and a turbine shaft on which the gas turbine and compressor are mounted. When starting a turbine engine, a relatively large amount of combustion energy is required to rotate the compressor, and since there is a large energy loss, it tends to take a long time from the start of startup until the turbine rotation speed stabilizes and the engine reaches a self-sustaining operating state.

[0004] In response to this, for example, Patent Document 1 describes a gas turbine engine system that functions as a charging system for charging a high-voltage battery of an electric vehicle with power when the charge level of the high-voltage battery becomes low, in which a generator motor of the gas turbine engine system functions as a starter when starting the gas turbine engine, thereby assisting in starting the gas turbine engine.

[0005] JP 2015-218711 A

[0006] In an electric vehicle equipped with a turbine generator, if the high-voltage battery that serves as the power source for the drive motor fails due to power depletion or other reasons, the generator motor of the turbine generator can be directly connected to the inverter of the drive motor, allowing the electric vehicle to travel at a minimum speed using the generated current of the turbine generator.

[0007] However, if the turbine engine is not started, the generator motor cannot be driven by the power of the high-voltage battery, and the turbine engine cannot be started, as described in Patent Document 1. In response to this, when the high-voltage battery fails, it is conceivable to start the turbine engine by connecting the low-voltage battery, which is a power source for various on-board electrical components, to the inverter of the generator motor.

[0008] However, the low-voltage battery, also known as the auxiliary battery, has a smaller capacity than the high-voltage battery, and therefore, if the low-voltage battery's power is used to start the turbine engine, the low-voltage battery may be depleted.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and an object of the present disclosure is to provide an electric power system, a turbine engine starting control method, and a vehicle that improve the startability of a turbine engine using power from a low-voltage battery.

[0010] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a power system including: a first battery that is a high-voltage power source; a second battery that is a low-voltage power source; a drive inverter that drives a drive motor of a vehicle using power from the first battery; a power generation inverter that controls power generation of a power generation motor of a turbine generator; and a turbine control device that controls the turbine generator, wherein, when starting a turbine engine of the turbine generator, if the first battery is normal, the turbine control device assists starting of the turbine engine by driving the power generation inverter using power from the first battery; and if the first battery is abnormal, the turbine control device electrically disconnects the first battery from the drive inverter and assists starting of the turbine engine by driving the power generation inverter using power from the second battery, and reduces power consumption when assisting starting of the turbine engine with power from the second battery compared to power consumption when assisting starting of the turbine engine with power from the first battery.

[0011] In order to solve the above-mentioned problems, according to another aspect of the present disclosure, there is provided a start-up control method for a turbine engine of a turbine generator, wherein a turbine control device that controls the turbine generator assists the start-up of the turbine engine by driving the power generation inverter with power from a first battery that is a high-voltage power source when the first battery is normal, and assists the start-up of the turbine engine by electrically disconnecting the first battery from the drive inverter when the first battery is abnormal, and driving the power generation inverter with power from a second battery that is a low-voltage power source when the first battery is abnormal, and the amount of power consumed when assisting the start-up of the turbine engine with power from the second battery is less than the amount of power consumed when assisting the start-up of the turbine engine with power from the first battery.

[0012] In order to solve the above-mentioned problems, according to another aspect of the present disclosure, there is provided a vehicle including a drive motor that is a drive power source for the vehicle, a first battery that is a high-voltage power source, a second battery that is a low-voltage power source, a drive inverter that drives the drive motor with power from the first battery, a power generation inverter that controls power generation of a power generation motor of a turbine generator, and a turbine control device that controls the turbine generator, wherein, when starting a turbine engine of the turbine generator, if the first battery is normal, the turbine control device assists starting of the turbine engine by driving the power generation inverter with power from the first battery, and if the first battery is abnormal, the turbine control device electrically disconnects the first battery and the drive inverter and assists starting of the turbine engine by driving the power generation inverter with power from the second battery, and the amount of power consumed when assisting starting of the turbine engine with power from the second battery is less than the amount of power consumed when assisting starting of the turbine engine with power from the first battery.

[0013] As described above, according to the present disclosure, it is possible to improve the startability of a turbine engine using power from a low-voltage battery.

[0014] 1 is an explanatory diagram showing an example of the overall configuration of an electric vehicle equipped with a power system according to the present embodiment; FIG. 2 is a block diagram showing a schematic configuration of the power system according to the present embodiment; FIG. 3 is a schematic diagram showing an example of the configuration of a turbine power generator; FIG. 4 is a block diagram showing an example of the configuration of a turbine control device of the power system according to the embodiment; FIG. 5 is a flowchart showing an example of control of the turbine power generator executed by the turbine control device of the power system according to the embodiment; FIG. 6 is a flowchart showing an example of control in normal mode executed by the turbine control device of the power system according to the embodiment; FIG. 7 is a flowchart showing an example of control in failsafe mode executed by the turbine control device of the power system according to the embodiment; FIG. 8 is an explanatory diagram showing the flow of power in normal mode of the power system according to the embodiment; FIG. 9 is an explanatory diagram showing the flow of power at the start of a turbine engine in normal mode of the power system according to the embodiment; FIG. 10 is an explanatory diagram showing the flow of power in failsafe mode of the power system according to the embodiment;

[0015] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0016] 1. Overall Configuration of Electric Vehicle First, the overall configuration of an electric vehicle equipped with a power system according to an embodiment of the present disclosure will be described.

[0017] Fig. 1 is an explanatory diagram showing an example of the overall configuration of an electric vehicle 1. Fig. 2 is a block diagram showing the schematic configuration of a power system 10 including a turbine generator 40.

[0018] The power system 10 of the electric vehicle 1 includes a first battery 14, a second battery 16, a front drive inverter 17F, a rear drive inverter 17R, a front drive motor 19F, a rear drive motor 19R, a connection switching device 18, a turbine generator unit 40, and a turbine control device 20. The power system 10 is used in a drive system that uses, as a drive power source, the front drive motor 19F and the rear drive motor 19R, which are driven by power supplied from the high-voltage first battery 14. The power system 10 is configured as a series hybrid system in which the electric power generated by the turbine generator unit 40 is charged into the first battery 14, thereby extending the range.

[0019] The first battery 14 is a high-voltage, large-capacity battery, and is formed, for example, by connecting a plurality of battery cells or battery modules in series. The first battery 14 is, for example, a battery with a rated voltage of 200 V. The rated voltage of the first battery 14 may be 24 V, 40 V, or the like, and is not particularly limited. The first battery 14 mainly supplies power to the drive motor 19. The first battery 14 also stores power generated by the drive motor 19 through regeneration and power generated by the turbine generator 40. In this embodiment, the power of the first battery 14 is also used to rotate the power generator motor 41.

[0020] The second battery 16 is a low-voltage battery with a smaller capacity than the first battery 14. The second battery 16 is, for example, a rated 12 V battery, and is a so-called auxiliary battery that serves as a power source for electrical components such as an on-board audio system, an air conditioning system, an electronic control unit, and electronic control devices. In this embodiment, the power of the second battery 16 is also used to drive the generator motor 41.

[0021] The front drive inverter 17F and the rear drive inverter 17R each include an inverter and a converter. When the electric vehicle 1 accelerates, the front drive inverter 17F converts DC current supplied from the first battery 14 or the turbine generator 40 into AC current and supplies the AC current to the front drive motor 19F, thereby causing the front drive motor 19F to output drive torque. When the electric vehicle 1 accelerates, the rear drive inverter 17R converts DC current supplied from the first battery 14 or the turbine generator 40 into AC current and supplies the AC current to the rear drive motor 19R, thereby causing the rear drive motor 19R to output drive torque. When the electric vehicle 1 decelerates, the front drive inverter 17F and the rear drive inverter 17R respectively regenerate power in the front drive motor 19F and the rear drive motor 19R, and convert the generated AC current into DC current to charge the first battery 14.

[0022] The electric vehicle 1 shown in FIG. 1 is a four-wheel drive vehicle. The front drive motor 19F outputs drive torque that is transmitted to the left and right front wheels via a differential mechanism 5F. The rear drive motor 19R outputs drive torque that is transmitted to the left and right rear wheels via a differential mechanism 5R. The front drive motor 19F and the rear drive motor 19R are, for example, three-phase AC radial motors, and output drive torque when AC current is supplied via a front drive inverter 17F and a rear drive inverter 17R, respectively, during acceleration of the electric vehicle 1. Meanwhile, the front drive motor 19F and the rear drive motor 19R generate electricity by regenerating power during deceleration.

[0023] The front drive motor 19F and the rear drive motor 19R may be axial gap motors. The electric vehicle 1 may be a front-wheel drive vehicle or a rear-wheel drive vehicle equipped with the front drive motor 19F or the rear drive motor 19R. The electric vehicle 1 may be configured to output drive torque transmitted from a single drive motor to the front wheels and the rear wheels, respectively, or may be equipped with a drive motor corresponding to each of the four wheels.

[0024] The electric vehicle 1 is equipped with an accelerator sensor 7, a brake sensor 8, and a wheel speed sensor 9. The accelerator sensor 7 and the brake sensor 8 detect the accelerator opening and the brake force or brake pressure, respectively, and output signals indicating the detection results to the vehicle control device 3. The wheel speed sensor 9 is provided on the front drive shaft and outputs a sensor signal corresponding to the rotation speed of the front drive shaft to the vehicle control device 3. The wheel speed sensor 9 may also be provided on the rear drive shaft.

[0025] The vehicle control device 3 controls the driving force of the electric vehicle 1 by having one or more processors execute a computer program. For example, the vehicle control device 3 calculates a target acceleration of the electric vehicle 1 based on information detected by the accelerator sensor 7, the brake sensor 8, and the wheel speed sensor 9, and controls the driving of the front drive inverter 17F and the rear drive inverter 17R based on the target acceleration.

[0026] The turbine generator 40 includes a power generation inverter 39, a power generation motor 41, and a turbine engine 42. The turbine engine 42 is a power generation engine whose output is not transmitted as drive torque for the electric vehicle 1. The turbine engine 42 converts the energy of high-temperature gas generated by heating compressed air into mechanical power and outputs the power. The power generation motor 41 is driven by the power output from the turbine engine 42 to generate electricity.

[0027] The power generating inverter 39 boosts the voltage of the power generated by the power generating motor 41 to the charging voltage (set charging voltage) of the first battery 14, and converts the generated AC current into DC current to supply to the first battery 14. The power generating inverter 39 also functions as a starter that is driven by the power generating inverter 39 when the turbine engine 42 is started, and rotates the turbine shaft of the turbine engine 42.

[0028] 3 is an explanatory diagram specifically illustrating the configuration of the turbine generator 40. The turbine engine 42 includes a compressor 43, a gas turbine 45, a combustor 51, and a heat exchanger 49. The compressor 43 draws in atmospheric air, compresses it to a predetermined pressure, and supplies the compressed gas to the combustor 51. The combustor 51 burns fuel therein, heats the compressed air supplied from the compressor 43, and generates high-temperature combustion gas, which is supplied to the gas turbine 45. The gas turbine 45 converts the energy of the high-temperature gas supplied from the combustor 51 into mechanical rotational energy and outputs it as rotational torque for a turbine shaft 47. The heat exchanger 49 heats the compressed air supplied from the compressor 43 to the combustor 51 using the heat of the exhaust gas discharged from the gas turbine 45.

[0029] The combustor 51 is provided with an on-off valve 57 that injects fuel into the combustor 51, a fuel control valve 55 that adjusts the amount of fuel supplied to the on-off valve 57, and an ignition plug 59 that ignites the fuel injected into the combustor 51. The turbine control device 20 controls the amount of fuel injected into the combustor 51 by driving the fuel control valve 55. The turbine control device 20 also drives the ignition plug 59 to combust the fuel.

[0030] The generator motor 41 is a three-phase AC generator equipped with a stator and a rotor and using permanent magnets. A turbine shaft 47 of the turbine engine 42 is connected to the rotor of the generator motor 41. The turbine shaft 47 and the rotor may be directly connected or may be connected via a power transmission mechanism such as a gear. The generator motor 41 generates electricity as the turbine shaft 47 rotates. The greater the output of the turbine engine 42, i.e., the higher the rotation speed of the turbine shaft 47 (turbine rotation speed), the greater the amount of electricity generated by the generator motor 41. The power output from the three-phase windings wound around the stator of the generator motor 41 is boosted to a battery charging set voltage by the generator inverter 39 and converted from AC to DC before being supplied to the first battery 14.

[0031] The power generation inverter 39 is provided with a current sensor 35 that detects the current value (generated current value) of the generated power output from the power generation motor 41, and a voltage sensor 37 that detects the voltage value (generated output voltage) of the generated power. The turbine engine 42 is also provided with a turbine rotation sensor 44 that detects the turbine rotation speed.

[0032] The connection switching device 18 is connected to each of the first battery 14, the second battery 16, the front drive inverter 17F, the rear drive inverter 17R, and the turbine generator 40. The connection switching device 18 includes a plurality of switches that switch the electrical connection states between the first battery 14, the second battery 16, the front drive inverter 17F, the rear drive inverter 17R, and the turbine generator 40.

[0033] The turbine control device 20 functions as a device that controls the operation of the turbine power generation device 40 by having one or more processors execute a computer program. The computer program is a computer program that causes the processor to execute the operations, described below, that should be performed by the turbine control device 20. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) provided in the turbine control device 20, or may be recorded on a recording medium built into the turbine control device 20 or any recording medium that can be externally attached to the turbine control device 20.

[0034] Examples of recording media for recording computer programs include magnetic media such as HDD (Hard Disk Drive), floppy disks, and magnetic tapes, optical recording media such as CD-ROM (Compact Disk Read Only Memory), DVD (Digital Versatile Disk), SSD (Solid State Drive), and Blu-ray (registered trademark), magneto-optical media such as floptical disks, memory elements such as RAM (Random Access Memory) and ROM (Read Only Memory), and flash memories such as USB (Universal Serial Bus) memories, as well as other media capable of storing programs.

[0035] In addition to the function of controlling the operation of the turbine generator 40, the turbine control device 20 may also have functions such as controlling the operation of the front drive inverter 17F and the rear drive inverter 17R to control the drive and regeneration of the front drive motor 19F and the rear drive motor 19R, and controlling the charging of the first battery 14. The functions and specific processing operations of the turbine control device 20 will be described in detail later.

[0036] 2. Turbine Control Device Next, the turbine control device 20 will be described in detail.

[0037] 4 is a block diagram showing an example configuration of the turbine control device 20. The turbine control device 20 includes a processing unit 21 and a storage unit 26. The processing unit 21 is configured to include one or more processors such as CPUs, and executes various arithmetic processes by executing computer programs. A part or all of the processing unit 21 may be configured with updatable firmware, or may be a program module executed by commands from the CPU, etc. The storage unit 26 is configured to include one or more storage elements such as RAM and ROM, or storage devices such as HDDs and SSDs, and is connected to the processing unit 21 so as to be able to communicate with it.

[0038] The turbine control device 20 is configured to be able to acquire information indicating the state of the first battery 14 from a battery controller (BMS: Battery Management System) 15 provided in the first battery 14. The information indicating the state of the first battery 14 includes, for example, information such as the open circuit voltage, output voltage, output current value, charge capacity, and temperature of the first battery 14. Furthermore, the turbine control device 20 is configured to be able to output drive commands to the connection switching device 18, the power generation inverter 39, and the fuel control valve 55.

[0039] The processing unit 21 includes a turbine power generation control unit 22, a connection switching control unit 23, and an assist control unit 24. Each of these units may have a function realized by a processor such as a CPU executing a computer program, or may be configured to include an analog circuit. Below, the function of each unit of the processing unit 21 will be briefly described, followed by a description of specific processing operations.

[0040] (Turbine power generation control unit) The turbine power generation control unit 22 controls power generation by the turbine power generation device 40. For example, the turbine power generation control unit 22 starts power generation when the remaining capacity SOC of the first battery 14 falls below a charge start threshold, and stops power generation when the remaining capacity SOC of the first battery 14 exceeds a charge end threshold. For example, the turbine power generation control unit 22 controls the operation of the turbine engine 42 while controlling the fuel injection amount so that the turbine rotation speed detected by the turbine rotation sensor 44 becomes a predetermined constant target rotation speed.

[0041] In this embodiment, the power system 10 is configured as a series hybrid system, which eliminates the need to change the output of the turbine engine 42 in response to increases or decreases in the drive torque of the electric vehicle 1. For this reason, the turbine power generation control unit 22 controls the operation of the turbine engine 42 so that the turbine rotation speed is basically a constant target rotation speed that allows stable, self-sustaining operation. The target rotation speed of the turbine engine 42 is set to a constant value regardless of the driver's accelerator operation. However, the target rotation speed may also be a variable value that is set to one of multiple stages depending on, for example, the remaining capacity SOC of the first battery 14. Even in this case, the target rotation speed is set to a value at least equal to or greater than the steady-state rotation speed.

[0042] The voltage of the AC power output from the generator motor 41 is determined according to the rotation speed of the generator motor 41, i.e., the turbine rotation speed. Therefore, the turbine power generation control unit 22 controls the drive of the power generation inverter 39 to convert the AC power output from the generator motor 41 into DC power and adjusts the voltage to the system voltage (battery charging voltage) before outputting it.

[0043] (Connection Switching Control Unit) The connection switching control unit 23 controls the connection switching device 18 to switch the electrical connection states between the first battery 14, the second battery 16, the front drive inverter 17F, the rear drive inverter 17R, and the turbine generator 40.

[0044] When the first battery 14 is normal, the connection switching control unit 23 electrically connects the first battery 14, the front drive inverter 17F, the rear drive inverter 17R, and the turbine generator unit 40. Hereinafter, this state will be referred to as the "normal connection state." In the normal connection state, the power generation inverter 39 is electrically connected to the high-voltage circuit to which the first battery 14 is electrically connected. In the normal connection state, the power generated by the turbine generator unit 40 can be charged into the first battery 14. Furthermore, the power of the first battery 14 can drive the front drive motor 19F and the rear drive motor 19R. Furthermore, the power of the first battery 14 can drive the power generation inverter 39 to assist in starting the turbine engine 42 of the turbine generator unit 40.

[0045] Furthermore, if the first battery 14 is abnormal, the connection switching control unit 23 electrically disconnects the first battery 14 from the front drive inverter 17F and the rear drive inverter 17R. Hereinafter, this state will be referred to as the "emergency connection state." In the emergency connection state, the power generating inverter 39 is electrically disconnected from the first battery 14. In the emergency connection state, at least one of the front drive motor 19F and the rear drive motor 19R can be driven by the power generated by the turbine generator unit 40. Furthermore, in the emergency connection state, if a start request for the turbine engine 42 is made, the power generating inverter 39 is electrically connected to the low-voltage circuit to which the second battery 16 is connected. This makes it possible to drive the power generating inverter 39 using power from the second battery 16 to assist in starting the turbine engine 42 of the turbine generator unit 40.

[0046] The connection switching control unit 23 determines whether the first battery 14 is normal or abnormal based on information output from the BMS 15. For example, the connection switching control unit 23 determines that the first battery 14 is abnormal when the remaining capacity SOC (State Of Charge) of the first battery 14 falls below a threshold that is even smaller than the charge start threshold or when the diagnosis result of the first battery 14 indicates an abnormality. In addition, the connection switching control unit 23 may obtain information indicating whether the first battery 14 is normal or abnormal from another control device such as the vehicle control device 3.

[0047] (Assist Control Unit) The assist control unit 24 assists in starting the turbine engine 42 of the turbine generator 40. When the turbine generator 40 is used as the generator of a series hybrid system, when attempting to start the turbine engine 42 by starting combustion in the combustor 51, it takes at least several tens of seconds for the turbine rotation speed to reach a steady rotation speed. Since sufficient power cannot be generated until the turbine rotation speed reaches the steady rotation speed, this leads to unnecessary consumption of combustion energy. For this reason, the assist control unit 24 drives the generator motor 41 as a starter to assist in increasing the turbine rotation speed.

[0048] When the first battery 14 is normal, the assist control unit 24 drives the power generation inverter 39 with the power of the first battery 14 to rotate the turbine shaft 47 and assist the starting of the turbine engine 42. When the first battery 14 is abnormal, the assist control unit 24 drives the power generation inverter 39 with the power of the second battery 16 to rotate the turbine shaft 47 and assist the starting of the turbine engine 42.

[0049] At this time, because the capacity of the second battery 16 is smaller than the capacity of the first battery 14, the assist control unit 24 changes the settings of the starting conditions for the turbine engine 42, and makes the amount of power consumed when assisting the start of the turbine engine 42 with the power of the second battery 16 less than the amount of power consumed when assisting the start of the turbine engine 42 with the power of the first battery 14. At this time, the assist control unit 24 makes the lower limit value of the voltage (DC link voltage) of the DC circuit that interconnects the drive inverters 17R lower than the lower limit value of the DC link voltage in the normal connection state.

[0050] The lower limit of the DC link voltage is set to perform an emergency shutdown of the power system 10 when the DC link voltage drops due to an abnormality or the like in the high-voltage first battery 14, and is set, for example, based on the lower limit of the output voltage of the first battery 14. If the lower limit of the DC link voltage is maintained in the normal connection state in the emergency connection state, there is a risk that the power of the low-voltage second battery 16 will not be able to assist in starting the turbine engine 42. For this reason, the assist control unit 24 sets the lower limit of the DC link voltage in the emergency connection state lower than the lower limit of the DC link voltage in the normal connection state, and based on, for example, the lower limit of the output voltage of the second battery 16.

[0051] 3. Operation of the Turbine Control Device So far, we have described exemplary configurations of the electric vehicle 1 equipped with the power system 10 and the turbine control device 20. Next, we will describe an example of the processing of starting the turbine engine 42, which is one of the processing operations of the turbine control device 20.

[0052] 5 to 7 are flowcharts showing an example of turbine engine startup control executed by the turbine control device 20. When the power system 10 is started (step S11), the processing unit 21 executes initialization processing (step S13). This initializes parameters used in calculations and various settings. In the initial state, the connection switching device 18 is in a normal connection state.

[0053] Next, the assist control unit 24 determines whether the first battery 14 is in a normal state (step S15). If the assist control unit 24 determines that the first battery 14 is in a normal state (S15 / Yes), the assist control unit 24 controls the turbine generator 40 in the normal mode (step S17).

[0054] 6 is a flowchart showing the normal mode processing by the turbine control device 20. In the normal mode, the connection switching control unit 23 drives the connection switching device 18 to set the normal connection state (step S31). In the normal connection state, the power generation inverter 39 is electrically connected to the high-voltage circuit to which the first battery 14 is electrically connected.

[0055] Next, the turbine power generation control unit 22 determines whether the turbine engine 42 is operating (step S33). For example, the turbine power generation control unit 22 determines that the turbine engine 42 is operating when a start completion flag for the turbine engine 42 is set or when the turbine rotation speed is equal to or greater than a predetermined determination threshold value.

[0056] If the turbine power generation control unit 22 determines that the turbine engine 42 is already operating (S33 / Yes), it executes power generation processing in normal mode (step S35). For example, the turbine power generation control unit 22 controls the operation of the turbine engine 42 so that the turbine rotation speed reaches a target rotation speed at which the turbine can stably operate independently at a constant value. The turbine power generation control unit 22 also controls the drive of the power generation inverter 39 to convert the AC power output from the power generation motor 41 into DC power and adjust the voltage to the system voltage (battery charging voltage) before outputting it.

[0057] 8 shows the flow of power when the power system 10 is in normal mode and the turbine engine 42 is operating. As shown in the figure, in this state, the power generated by the turbine generator 40 is supplied to the high-voltage circuit, and the first battery 14 is charged or discharged depending on the drive states of the front drive motor 19F and the rear drive motor 19R.

[0058] On the other hand, if the turbine power generation control unit 22 does not determine that the turbine engine 42 is operating (No in S33), the assist control unit 24 determines whether or not there is a request to start the turbine engine 42 (step S37). For example, the assist control unit 24 determines that there is a request to start the turbine engine 42 when the remaining capacity SOC of the first battery 14 is below the charge start threshold.

[0059] If the assist control unit 24 does not determine that there is a request to start the turbine engine 42 (S37 / No), it does not start the turbine engine 42 and keeps the turbine generator 40 in a state where power generation is not performed. On the other hand, if the assist control unit 24 determines that there is a request to start the turbine engine 42 (S37 / Yes), it drives the power generation inverter 39 with power from the first battery 14 to rotate the turbine shaft 47 and assist the start of the turbine engine 42 (step S39).

[0060] 9 shows the flow of power when the power system 10 is in normal mode and the turbine engine 42 is started. As shown in the figure, in this state, charging and discharging of the first battery 14 is performed according to the drive states of the front drive motor 19F and the rear drive motor 19R. In addition, the power generation inverter 39 is driven by power supplied from the high-voltage circuit, and the turbine engine 42 is started.

[0061] When the start of the turbine engine 42 is completed, the turbine power generation control unit 22 executes the power generation process in the normal mode (step S35).

[0062] 5 , the turbine power generation control unit 22 determines whether the power system 10 has stopped while controlling the turbine power generation device 40 in the normal mode (step S19). If the turbine power generation control unit 22 does not determine that the power system 10 has stopped (S19 / No), the process returns to step S15.

[0063] On the other hand, in step S15, if the assist control unit 24 does not determine that the first battery 14 is in a normal state (S15 / No), the assist control unit 24 controls the turbine generator 40 in a fail-safe mode (step S21).

[0064] 7 is a flowchart showing the fail-safe mode processing by the turbine control device 20. In the fail-safe mode, the connection switching control unit 23 drives the connection switching device 18 to set the connection state for emergency (step S41). In the normal connection state, the first battery 14 is electrically disconnected. Next, the turbine power generation control unit 22 determines whether the turbine engine 42 is operating (step S43), similar to step S33.

[0065] If the turbine power generation control unit 22 does not determine that the turbine engine 42 is operating (No in S43), the connection switching control unit 23 drives the connection switching device 18 to electrically connect the power generation inverter 39 to the low-voltage circuit to which the second battery 16 is electrically connected (step S47). Next, the assist control unit 24 changes the setting of the start condition of the turbine engine 42 (step S49). The change in the setting of the start condition of the turbine engine 42 is performed to prevent the second battery 16 from running out of power during start-up of the turbine engine 42 due to the capacity of the second battery 16 being smaller than the capacity of the first battery 14.

[0066] For example, the assist control unit 24 sets the lower limit of the DC link voltage of the DC circuit to which the power generation inverter 39 is connected lower than the lower limit of the DC link voltage in a normal connection state. This change in the lower limit prevents the power system 10 from being brought to an emergency stop when the DC link voltage drops due to disconnection of the first battery 14 from the DC circuit and connection of the second battery 16.

[0067] Furthermore, the assist control unit 24 changes the settings so that the amount of power consumed when assisting the start of the turbine engine 42 with power from the second battery 16 is less than the amount of power consumed when assisting the start of the turbine engine 42 with power from the first battery 14. For example, the assist control unit 24 slows the rate of increase in the turbine rotation speed (rotational acceleration) when assisting the start of the turbine engine 42 with power from the second battery 16 compared to the rate of increase in the turbine rotation speed when assisting the start of the turbine engine 42 with power from the first battery 14. This limits the amount of power required to rotate the turbine shaft 47 using the generator motor 41 as a starter and increase the turbine rotation speed, thereby keeping the amount of power consumed by the second battery 16 low.

[0068] Furthermore, instead of lowering the target rotation speed of the turbine engine 42, or in addition to lowering the target rotation speed of the turbine engine 42, the assist control unit 24 may lower the target rotation speed of the turbine engine 42 when assisting the start of the turbine engine 42 with electric power from the second battery 16 compared to the target rotation speed of the turbine engine 42 when assisting the start of the turbine engine 42 with electric power from the first battery 14. For example, the assist control unit 24 changes the target rotation speed when starting the turbine engine 42 and setting the turbine rotation speed to a constant value from 25,000 rpm to 20,000 rpm. This makes it possible to slow down the rate at which the turbine rotation speed increases until it reaches the target rotation speed, and to keep the amount of power consumed by the second battery 16 low.

[0069] After changing the settings of the starting conditions for the turbine engine 42, the assist control unit 24 drives the power generating inverter 39 with power from the second battery 16 to rotate the turbine shaft 47 and assist the starting of the turbine engine 42 (step S51). By changing the settings of the starting conditions for the turbine engine 42, power consumption is kept low while the turbine engine 42 is starting.

[0070] 10 shows the flow of power when the power system 10 is in the fail-safe mode and the turbine engine 42 is started. As shown in the figure, in this state, the first battery 14 is not charged or discharged, the power generating inverter 39 is driven by power supplied from the low-voltage circuit, and the turbine engine 42 is started.

[0071] Next, when the start-up of the turbine engine 42 is completed, the connection switching control unit 23 drives the connection switching device 18 to electrically disconnect the power generation inverter 39 from the low-voltage circuit to which the second battery 16 is electrically connected (step S53).

[0072] After the connection switching control unit 23 electrically disconnects the power generation inverter 39 from the low-voltage circuit to which the second battery 16 is electrically connected (step S53), or if the turbine power generation control unit 22 determines that the turbine engine 42 is already operating (S43 / Yes), the turbine power generation control unit 22 executes power generation processing in fail-safe mode (step S45). For example, the turbine power generation control unit 22 controls the operation of the turbine engine 42 so that the turbine rotation speed is a constant, minimum target rotation speed that allows stable, self-sustained operation. The turbine power generation control unit 22 also controls the drive of the power generation inverter 39 to convert AC power output from the power generation motor 41 into DC power and adjusts and outputs the output voltage.

[0073] In the fail-safe mode, because the first battery 14 is in an abnormal state, the drive torque of the electric vehicle 1 is limited to the minimum torque required for the electric vehicle 1 to move to a repair shop, etc. In addition, in the fail-safe mode, the generated power of the turbine generator 40 is not charged into the first battery 14 or the second battery 16, so the turbine engine 42 is controlled at the minimum target rotation speed that allows stable, self-sustaining operation at a constant turbine rotation speed.

[0074] 11 shows the flow of power when the power system 10 is in fail-safe mode and the turbine engine 42 is operating. As shown in the figure, in this state, the power generated by the turbine generator 40 is supplied to the front drive motor 19F via the front drive inverter 17F. Note that the power generated by the turbine generator 40 may be supplied to the rear drive motor 19R via the rear drive inverter 17R, or may be supplied to both the front drive motor 19F and the rear drive motor 19R.

[0075] 5 , while controlling the turbine generator 40 in the fail-safe mode, the turbine generator control unit 22 determines whether the power system 10 has stopped (step S23). If the turbine generator control unit 22 does not determine that the power system 10 has stopped (S23 / No), the process returns to step S21 and continues control in the fail-safe mode.

[0076] When the turbine power generation control unit 22 determines in step S19 or step S23 that the power system 10 has stopped (S19 / Yes or S23 / Yes), the turbine power generation control unit 22 ends the processing of the turbine control device 20.

[0077] 4. Effects As described above, the power system 10 according to this embodiment includes the first battery 14 which is a high-voltage power source, the second battery 16 which is a low-voltage power source, drive inverters 17F, 17R which drive the front drive motor 19F and the rear drive motor 19R with power from the first battery 14, the power generation inverter 39 which controls power generation of the power generation motor 41 of the turbine power generation unit 40, and the turbine control device 20 which controls the turbine power generation unit 40. When starting the turbine engine 42 of the turbine generator 40, if the first battery 14 is normal, the turbine control device 20 assists in starting the turbine engine 42 by driving the power generation inverter 39 with the power of the first battery 14, and if the first battery 14 is abnormal, the turbine control device 20 electrically disconnects the first battery 14 from the drive inverters 17F, 17R and assists in starting the turbine engine 42 by driving the power generation inverter 39 with the power of the second battery 16, and makes the amount of power consumed when assisting in starting the turbine engine 42 with the power of the second battery 16 less than the amount of power consumed when assisting in starting the turbine engine 42 with the power of the first battery 14.

[0078] As a result, even if the turbine generator 40 is not started when an abnormality occurs in the high-voltage first battery 14, it is possible to start the turbine generator 40 and continue running the electric vehicle 1. Furthermore, the amount of power consumed while starting the turbine engine 42 using power from the second battery 16 is kept low, reducing the risk of the second battery 16 running out of power.

[0079] Furthermore, in the power system 10 according to this embodiment, the turbine control device 20 slows the rate at which the rotation speed of the turbine engine 42 increases when the start of the turbine engine 42 is assisted by the power of the second battery 16, compared to the rate at which the rotation speed of the turbine engine 42 increases when the start of the turbine engine 42 is assisted by the power of the first battery 14. This makes it possible to slow the rate at which the turbine rotation speed increases until it reaches the target rotation speed, thereby reducing the torque required to start the turbine engine 42 and keeping the amount of power consumed by the second battery 16 low.

[0080] In the power system 10 according to this embodiment, the turbine control device 20 may set the target rotation speed of the turbine engine 42 when assisting the start of the turbine engine 42 with electric power from the second battery 16 to be lower than the target rotation speed of the turbine engine 42 when assisting the start of the turbine engine 42 with electric power from the first battery 14. This can slow down the rate at which the turbine rotation speed increases until it reaches the target rotation speed, reducing the torque required to start the turbine engine 42 and keeping the amount of electric power consumed by the second battery 16 low.

[0081] Furthermore, in the power system 10 according to this embodiment, the turbine control device 20 sets the lower limit of the DC link voltage of the power generating inverter 39 when assisting the start of the turbine engine 42 with power from the second battery 16 to be lower than the lower limit of the DC link voltage of the power generating inverter 39 when assisting the start of the turbine engine 42 with power from the first battery 14. This prevents the power system 10 from being forced to an emergency stop due to a drop in the DC link voltage caused by disconnecting the first battery 14 from the DC circuit and connecting the second battery 16.

[0082] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technology of the present disclosure is not limited to such examples. It is clear that a person skilled in the art of the technology to which the present disclosure pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0083] The technology of the present disclosure can also be realized as a vehicle equipped with the turbine control device 20 described in the above embodiment, a method for controlling the start-up of a turbine engine using the turbine control device 20, a computer program that causes a computer to function as the above-mentioned turbine control device 20, and a non-transitory tangible recording medium on which the computer program is recorded.

[0084] 1: Electric vehicle 10: Power system 14: First battery 16: Second battery 17F: Front drive inverter 17R: Rear drive inverter 18: Connection switching device 19F: Front drive motor 19R: Rear drive motor 20: Turbine control device 21: Processing unit 22: Turbine power generation control unit 23: Connection switching control unit 24: Assist control unit 39: Power generation inverter 40: Turbine power generation unit 41: Power generation motor 42: Turbine engine

Claims

1. A power system comprising: a first battery which is a high-voltage power source; a second battery which is a low-voltage power source; a drive inverter which drives a vehicle drive motor using power from the first battery; a power generation inverter which controls power generation of a power generation motor of a turbine generator; and a turbine control device which controls the turbine generator, wherein, when starting a turbine engine of the turbine generator, if the first battery is normal, the turbine control device assists the start of the turbine engine by driving the power generation inverter using power from the first battery; if the first battery is abnormal, the turbine control device electrically disconnects the first battery from the drive inverter and assists the start of the turbine engine by driving the power generation inverter using power from the second battery; and reduces the amount of power consumed when assisting the start of the turbine engine using power from the second battery compared to the amount of power consumed when assisting the start of the turbine engine using power from the first battery.

2. The power system according to claim 1, wherein the turbine control device sets the target rotational speed of the turbine engine when assisting the start of the turbine engine with the power of the second battery to be lower than the target rotational speed of the turbine engine when assisting the start of the turbine engine with the power of the first battery.

3. The power system according to claim 1, wherein the turbine control device slows down the rate at which the rotational speed of the turbine engine increases when assisting the start of the turbine engine with the power of the second battery compared to the rate at which the rotational speed of the turbine engine increases when assisting the start of the turbine engine with the power of the first battery.

4. The power system according to claim 1, wherein the turbine control device sets a lower limit value of the DC link voltage of the power generating inverter when assisting the start of the turbine engine with the power of the second battery to be lower than a lower limit value of the DC link voltage of the power generating inverter when assisting the start of the turbine engine with the power of the first battery.

5. A method for controlling the start-up of a turbine engine of a turbine generator set, comprising: when a first battery, which is a high-voltage power source, is normal, assisting the start-up of the turbine engine by driving a power generation inverter that controls the power generation of a power generation motor of the turbine generator set with the power of the first battery; when the first battery is abnormal, electrically disconnecting the first battery from a drive inverter that drives a drive motor with the power of the first battery, and assisting the start-up of the turbine engine by driving the power generation inverter with the power of a second battery, which is a low-voltage power source; and reducing the amount of power consumed when assisting the start-up of the turbine engine with the power of the second battery compared to the amount of power consumed when assisting the start-up of the turbine engine with the power of the first battery.

6. A vehicle comprising: a drive motor which is a drive power source for the vehicle; a first battery which is a high-voltage power source; a second battery which is a low-voltage power source; a drive inverter which drives the drive motor with power from the first battery; a power generation inverter which controls power generation of a power generation motor of a turbine generator; and a turbine control device which controls the turbine generator, wherein, when starting a turbine engine of the turbine generator, if the first battery is normal, the turbine control device assists the start of the turbine engine by driving the power generation inverter with power from the first battery; if the first battery is abnormal, the turbine control device electrically disconnects the first battery and the drive inverter and assists the start of the turbine engine by driving the power generation inverter with power from the second battery; and reduces the amount of power consumed when assisting the start of the turbine engine with power from the second battery compared to the amount of power consumed when assisting the start of the turbine engine with power from the first battery.

Images