Electric vehicles

Abstract

To provide an electric vehicle which can supply energy required for power running while being shared by a plurality of power storage devices, steps down the output voltages of the power storage devices and makes the output voltages with DC voltage setting of an inverter because there is no limit in a step-down ratio of a power converter, and thereby can widen the widths of lower limit setting and upper limit setting of the inverter DC voltage.SOLUTION: In power running of a motor 1, the output voltage of a first power storage device 4 is stepped down by a power converter 10, energy is supplied to an inverter 2 from the first power storage device 4 and a second power storage device 5, a power storage state of the second power storage device 4 can be determined on the basis of the voltage of the second power storage device 5, and in regeneration of the motor 1, when the number of rotation of the motor 1 is equal to or less than a predetermined number of rotation and the power storage state of the second power storage device 5 is equal to or less than a predetermined upper limit value, regenerative energy is recovered by the second power storage device 5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric vehicle equipped with a motor capable of power running and regenerating, and an electricity storage device capable of supplying energy to the motor. [Background technology]

[0002] An example of an electric vehicle that is equipped with a motor capable of power running and regenerating electricity and an electricity storage device capable of supplying energy to the motor, obtains thrust from the driving force of the motor, and is capable of recovering energy in the electricity storage device by adjusting the braking torque of the drive wheels, is described in Patent Document 1. With such an electric vehicle, energy recovered during braking can be stored in the electricity storage device (battery) and used as driving energy during power running. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-166367 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, power storage devices (high-capacity power storage devices and high-output power storage devices) with different characteristics are provided, and the output voltage of each power storage device is boosted to match the DC voltage setting of the inverter. Therefore, although the energy required during power running can be shared and supplied by the multiple power storage devices, there is a problem in that there is a limit to the boost ratio of the power converter, and the range between the lower limit and upper limit settings of the inverter's DC voltage is limited.

[0005] The present invention has been made in view of the above circumstances, and aims to provide an electric vehicle in which the energy required during power running can be shared and supplied by a plurality of power storage devices, and since there is no limit to the step-down ratio of the power converter, the output voltage of the power storage devices can be stepped down to match the DC voltage setting of the inverter, thereby making it possible to widen the range in which the lower and upper limits of the inverter DC voltage can be set. [Means for solving the problem]

[0006] The invention of claim 1 is an electric vehicle having a motor capable of powering and regenerating, and an inverter capable of converting direct current to alternating current, the electric vehicle comprising: a first storage device having high-capacity characteristics; a second storage device having high-output characteristics; a power converter having a function of reducing voltage during powering; and a circuit in which the power converter is connected to each of the first and second storage devices so that they are in parallel; when the motor is powering, the output voltage of the first storage device is reduced by the power converter, and energy is supplied from the first and second storage devices to the inverter; the storage state of the second storage device can be determined based on the voltage of the second storage device; and when the motor is regenerating, if the rotation speed of the motor is equal to or lower than a predetermined rotation speed and the storage state of the second storage device is equal to or lower than a predetermined upper limit value, regenerated energy is recovered by the second storage device.

[0007] The invention of claim 2 is characterized in that, in the electric vehicle of claim 1, the power converter has a function of stepping down during power running and a function of stepping up during regeneration, and when the motor is regenerating, it steps up the DC voltage of the inverter and recovers energy in the first storage device and the second storage device.

[0008] The invention of claim 3 is an electric vehicle of claim 1 or claim 2, in which the storage state of the second storage device can be determined based on the voltage of the second storage device, and when the motor is powered, if the rotation speed of the motor is equal to or lower than a predetermined rotation speed and the storage state of the second storage device is equal to or higher than a predetermined intermediate value, energy is supplied from the second storage device to the inverter.

[0009] The invention of claim 4 is characterized in that, in the electric vehicle of any one of claims 1 to 3, the power converter has a plurality of semiconductor switch elements, and during power running, the power converter reduces the voltage of the first power storage device or the second power storage device by switching on and off the switches of the semiconductor switch elements at high speed, and during regeneration, the power converter increases the voltage of the first power storage device or the second power storage device by switching on and off the switches of the semiconductor switch elements at high speed.

[0010] The invention of claim 5 is characterized in that in the electric vehicle of any one of claims 1 to 4, charging and discharging are controlled so that the voltage of the first power storage device is equal to or higher than the voltage of the second power storage device.

[0011] The invention of claim 6 is characterized in that, in the electric vehicle of any one of claims 1 to 5, when controlling the current of the inverter, the DC voltage of the inverter can be controlled according to the rotation speed of the motor, and when the rotation speed of the motor is equal to or lower than a predetermined rotation speed, the DC voltage of the inverter is controlled to be lower as the rotation speed of the motor becomes lower.

[0012] The invention of claim 7 is characterized in that, in the electric vehicle of any one of claims 1 to 6, when the current of the inverter is controlled and the rotation speed of the motor is equal to or lower than a predetermined rotation speed, the DC voltage of the inverter is controlled in accordance with the peak value of the motor line voltage.

[0013] The invention described in claim 8 is characterized in that, in the electric vehicle described in any one of claims 1 to 7, the first power storage device is a high-capacity lithium-ion battery or a high-capacity nickel-metal hydride battery, and the second power storage device is any one of a high-output lithium-ion battery, a high-output nickel-metal hydride battery, a lithium-ion capacitor, or an electric double layer capacitor. [Effects of the Invention]

[0014] According to the present invention, when the motor is powered, the output voltage of the first storage device is stepped down by the power converter, and energy is supplied to the inverter from the first storage device and the second storage device. Therefore, the energy required during powering can be shared and supplied by a plurality of storage devices, and since there is no limit to the step-down ratio of the power converter, the range between the lower limit and upper limit settings of the inverter DC voltage can be widened by stepping down the output voltage of the storage device to match the DC voltage setting of the inverter. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an electric vehicle according to an embodiment of the present invention; [Figure 2] A circuit diagram showing a power conversion device of the electric vehicle [Figure 3] Conceptual diagram showing the power conversion device for the electric vehicle [Figure 4] Schematic diagram showing the power control relationship of the electric vehicle [Figure 5] Time chart showing power control of the electric vehicle [Figure 6] 1 is a flowchart showing the overall power control of the electric vehicle. [Figure 7] Graph showing the required characteristics of the electric vehicle (vehicle requirements for drive wheels) [Figure 8] Graph showing the required characteristics of the electric vehicle (motor requirements for the drive wheels) [Figure 9] Graph showing the required characteristics of the electric vehicle (vehicle requirements for the driven wheels) [Figure 10] Graph showing the required characteristics of the electric vehicle (braking requirements for the driven wheels) [Figure 11] A flowchart showing request processing control of the electric vehicle. [Figure 12] Graph showing the driver's request table (Table 1) of the electric vehicle [Figure 13] Graph showing the driver's request table (Table 2) of the electric vehicle [Figure 14] Graph showing the driver's request table (Table 3) of the electric vehicle [Figure 15]Graph showing the driver's request table (Table 4) of the electric vehicle [Figure 16] 1 is a flowchart showing motor control for power control of the electric vehicle. [Figure 17] 1 is a flowchart showing motor control for power control of the electric vehicle. [Figure 18] Table showing the power conversion circuit control of the electric vehicle [Figure 19] Graph showing the voltage requirement table for the same electric vehicle (Table A for PWM) [Figure 20] Graph showing the voltage requirement table for the same electric vehicle (Table B for PWM) [Figure 21] Graph showing the voltage requirement table for the same electric vehicle (Table A for the case of motor line voltage peak value dependent type) [Figure 22] Graph showing the voltage requirement table for the same electric vehicle (Table B for the case of motor line voltage peak value dependent type) [Figure 23] A time chart showing an example of operation dependent on the peak value of the motor line voltage of an electric vehicle according to another embodiment. [Figure 24] Graph showing the state of charge of the first power storage device of the electric vehicle [Figure 25] Graph showing the state of charge of the second power storage device of the electric vehicle [Figure 26] Table showing combinations of storage devices for the electric vehicle [Figure 27] FIG. 10 is a circuit diagram showing a power conversion device for an electric vehicle according to another embodiment of the present invention; [Figure 28] Conceptual diagram showing the power conversion device for the electric vehicle [Figure 29] Table showing the power conversion circuit control of the electric vehicle DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The electric vehicle according to this embodiment is a saddle-type vehicle such as a motorcycle that can be driven by the driving force of a motor, and as shown in FIGS. 1 to 4, is mainly equipped with a motor 1, an inverter 2, mechanical brakes (3a, 3b), a first power storage device 4, a second power storage device 5, an accelerator operation means 6, a mechanical brake operation means 7, a regenerative brake operation means 8, a power converter 10, an ECU 11, a start switch 12, and a monitor 13 (auxiliary device).

[0017] The motor 1 is an electromagnetic motor that obtains driving force from energy supply, and as shown in Figures 2 and 3, is electrically connectable to the second power storage device 5, power converter 10, and first power storage device 4 via the inverter 2, and is capable of power running and regeneration. The inverter 2 (DC-AC inverter) is capable of converting direct current to alternating current, and in this embodiment, it is capable of converting the direct current of the first power storage device 4 and the second power storage device 5 into alternating current and supplying it to the motor 1.

[0018] The mechanical brakes are comprised of braking devices such as disc brakes or drum brakes that can apply braking by releasing energy, and are configured with a driving wheel mechanical brake 3a that applies braking by releasing the kinetic energy of the driving wheels Ta, and a driven wheel mechanical brake 3b that applies braking by releasing the kinetic energy of the driven wheels Tb. The driving wheel mechanical brakes 3a and driven wheel mechanical brakes 3b are connected to a mechanical brake operating means 7 via a brake actuator 9.

[0019] The mechanical brake operating means 7 is composed of a part (in this embodiment, an operating lever attached to the right end of the handlebar) that can control the mechanical brake (driven wheel mechanical brake 3b) to adjust the braking torque, and is configured so that the mechanical brake control unit 18 (see Figure 4) operates the brake actuator 9 in accordance with the amount of operation, thereby operating the driven wheel mechanical brake 3b.

[0020] The accelerator operation means 6 is made up of a part (in this embodiment, an accelerator grip attached to the right end of the handlebar) that can control the motor 1 to adjust the drive torque of the drive wheel Ta, and as shown in Figure 4, the inverter control unit 16 estimates the torque requirement according to the amount of operation and operates the motor 1 to obtain the desired drive force. The inverter control unit 16 is one of the control units formed in the ECU 11.

[0021] The power storage device is capable of supplying energy to the motor 1, and in this embodiment, is configured to include a first power storage device 4 and a second power storage device 5. The first power storage device 4 is made up of a storage battery having high-capacity characteristics, and as shown in FIG. 26, for example, a high-capacity lithium-ion battery or a high-capacity nickel-metal hydride battery can be used. The second power storage device 5 is made up of a storage battery having high-output characteristics, and as shown in FIG. 26, for example, any one of a high-output lithium-ion battery, a high-output nickel-metal hydride battery, a lithium-ion capacitor, or an electric double layer capacitor can be used.

[0022] The regenerative brake operation means 8 is made up of a component (in this embodiment, an operating lever attached to the left end of the handlebar) that controls the motor 1 to adjust the braking torque of the drive wheel Ta and recover energy in the first power storage device 4 and the second power storage device 5, and is configured to perform regeneration of the motor 1 according to the amount of operation to obtain a desired braking force. By this regeneration of the motor 1, energy can be recovered in the first power storage device 4 and the second power storage device 5.

[0023] The power converter 10 has a function of stepping down the voltage when the motor 1 is powered (when energy is supplied to the motor 1) and a function of stepping up the voltage when the motor 1 is regenerating (when energy is recovered from the motor 1), and is connected between the second power storage device 5 and the inverter 2 in the electric circuit as shown in Figures 2 and 3. More specifically, as shown in Figure 2, the power converter 10 is configured to have switches S1, S2, S3 (S3L, S4R), three semiconductor switch elements (MOSFETs) 10a, 10b, 10d each having a diode as a rectifier, and a reactor 10c (coil).

[0024] Furthermore, according to the power converter 10 of this embodiment, by performing high-speed switching (duty control) on the switches S1, S2, and S3 (S3L, S4R) of the semiconductor switch elements 10a, 10b, and 10d, when the motor 1 is powered (when current flows to the right in FIG. 3), the reactor 10c is located downstream of the semiconductor switch elements 10a, 10b, and 10d, making it possible to step down the voltage, and when the motor 1 is regenerating (when current flows to the left in FIG. 3), the reactor 10c is located upstream of the semiconductor switch elements 10a, 10b, and 10d, making it possible to step up the voltage.

[0025] More specifically, in this embodiment, as shown in Figures 2 and 3, a circuit is provided in which a power converter 10 is connected to each of the first and second storage devices 4 and 5 so that the first and second storage devices 4 and 5 are connected in parallel, and when the motor 1 is powered, the power converter 10 reduces the output voltage of the first storage device 4 and supplies energy from the first and second storage devices 4 and 5 to the inverter 2, and when the motor 1 is regenerating, the DC voltage of the inverter 2 is increased and energy is recovered by the first and second storage devices 4 and 5.

[0026] In this embodiment, as shown in FIG. 2, a switch Sa is formed that is turned on when the power converter 10 is off, and capacitors Ca and Cb are connected for stabilization.

[0027] 2, in this embodiment, the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 share a ground connection switch (semiconductor switch element 10b), and the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 share a reactor 10c. Furthermore, charge and discharge control is performed so that the voltage of the first power storage device 4 according to this embodiment becomes equal to or higher than the voltage of the second power storage device 5.

[0028] The ECU 11 controls the motor 1 and the like in response to input requests from the driver, and as shown in Fig. 4, has an inverter control unit 16, a circuit control unit 17, and a mechanical brake control unit 18, and is connected to the inverter 2, the power converter 10, the first power storage device 4, the second power storage device 5, and the brake actuator 9. The ECU 11 is also capable of detecting the voltages of the first power storage device 4 and the second power storage device 5, and is capable of determining the power storage states of the first power storage device 4 and the second power storage device 5 based on these voltages. The power storage state of the first power storage device 4 is shown in Fig. 24, and the power storage state of the second power storage device 5 is shown in Fig. 25.

[0029] However, when the motor 1 is powered, if the rotation speed of the motor 1 is equal to or lower than a predetermined rotation speed and the storage state of the second storage device 5 is equal to or higher than a predetermined intermediate value (see Figure 25), energy is supplied from the second storage device 5 to the inverter 2, and when the motor 1 is regenerating, if the rotation speed of the motor 1 is equal to or lower than a predetermined rotation speed and the storage state of the second storage device 5 is equal to or lower than a predetermined upper limit value (see Figure 25), the regenerative energy is recovered by the second storage device 5.

[0030] The start switch 12 is an operating switch that enables the vehicle to run, and after operating the start switch 12, the accelerator operating means 6 is operated to start the motor 1 and make the vehicle run. The monitor 13 is an auxiliary device such as a liquid crystal monitor attached to the vehicle, and is capable of displaying, for example, the vehicle's status (speed, battery status, presence or absence of malfunctions, etc.) and a map from a navigation system.

[0031] 4, this embodiment is provided with detection means 19 consisting of a sensor that detects the rotation speed of motor 1, and is configured so that when the rotation speed of motor 1 detected by detection means 19 is equal to or greater than a predetermined value, a predetermined braking torque corresponding to the amount of operation of regenerative brake operation means 8 is generated by the regenerative brake (particularly in this embodiment, generated only by the regenerative brake). Furthermore, during regeneration of motor 1, the maximum value of the predetermined braking torque is set to the rated torque of motor 1.

[0032] Furthermore, when the rotation speed of motor 1 detected by detection means 19 is less than a predetermined value, braking torque is generated by the mechanical brake (driving wheel mechanical brake 3a) in accordance with the amount of operation of regenerative brake operation means 8. In addition, when the amount of charge of first power storage device 4 is equal to or greater than a predetermined value, braking torque is generated by the mechanical brake (driving wheel mechanical brake 3a) in accordance with the amount of operation of regenerative brake operation means 8.

[0033] Fig. 5 shows changes in each parameter when the accelerator operation means 6 and the regenerative brake operation means 8 are operated after the start switch 12 is turned on in the electric vehicle according to the above embodiment. In particular, the capacitor current (Ic) and capacitor capacity (SOC2) indicate the current and capacity of the second power storage device 5 of this embodiment, and the battery current (Idc) and battery capacity (SOC1) indicate the current and capacity of the first storage battery 4 of this embodiment. Note that "FCCNO" (function circuit control number) in the table in the figure corresponds to the "FCCNO" shown in Figs. 4, 16 to 18.

[0034] Next, the control (main control) of the electric vehicle according to this embodiment will be described with reference to the flowchart of FIG. First, in S1, it is determined whether or not start switch 12 is turned on. If it is determined that start switch 12 is turned on, it is determined in S2 whether or not the state of charge (Soc1) of first power storage device 4 is greater than a predetermined lower limit (see FIG. 28). If it is determined that the state of charge (Soc1) is greater than the predetermined lower limit, request processing (S3), motor control (S4), and mechanical brake control (S5) are performed in this order.

[0035] Next, the required characteristics of the electric vehicle according to this embodiment will be described with reference to FIGS. The relationship between the driving torque and braking torque at the driving wheels Ta and the vehicle speed has the characteristics shown in Figure 7, and the relationship between the motor torque at the driving wheels Ta and the rotation speed (ω) of the motor 1 has the characteristics shown in Figure 8. In particular, as shown in Figure 7, when the vehicle is traveling at high speed, the driving torque and braking torque gradually decrease with the vehicle speed. In Figure 8, the plus side (upper half) of the vertical axis indicates the driving torque corresponding to the amount of operation of the accelerator operation means 6, and the minus side (lower half) of the vertical axis indicates the braking torque corresponding to the amount of operation of the regenerative brake operation means 8. The symbol Tm1 in the figure indicates the rated torque of the motor 1.

[0036] The relationship between the braking torque at the driven wheel Tb and the vehicle speed has the characteristics shown in FIG. 9, and the relationship between the braking torque at the driven wheel Tb (mechanical braking torque (Tbmf)) and the rotation speed (ω) of the motor 1 has the characteristics shown in FIG. 10. Note that, since FIGS. 9 and 10 show the characteristics of the driven wheel Tb, only the characteristics (braking torque) on the negative side (lower half) of the vertical axis are shown.

[0037] Next, control (request processing control) of the electric vehicle according to this embodiment will be described with reference to the flowchart of FIG. First, in S1, it is determined whether the regenerative system is normal or not based on the presence or absence of a fault signal. If it is determined that there is no fault signal, it is determined in S2 whether the accelerator operation means 6 is being operated (whether the accelerator operation amount Ap is greater than 0). If it is determined that the accelerator operation means 6 is being operated, the process proceeds to S4, where the motor torque (Tm) corresponding to the operation amount of the accelerator operation means 6 is calculated based on Table 1 shown in FIG. 12.

[0038] After the calculation in S4, in S7, a mechanical braking torque (Tbmr) corresponding to the amount of operation of the regenerative brake operation means 8 is calculated based on Table 3 shown in Fig. 14, and in S10, a mechanical braking torque (Tbmf) corresponding to the amount of operation of the mechanical brake operation means 7 is calculated based on Table 4 shown in Fig. 15. Furthermore, if it is determined in S2 that the accelerator operation means is not being operated, it is determined in S3 whether regeneration of the motor 1 is possible. This determination is made when the state of charge (Soc1) of the first power storage device 4 is equal to or less than a predetermined upper limit (see Fig. 24) and the motor rotation speed is equal to or greater than ω1 (see Fig. 8).

[0039] If it is determined in S3 that regeneration of the motor 1 is possible, the process proceeds to S5, where the motor torque (Tm) corresponding to the amount of operation of the regenerative brake operation means 8 is calculated based on Table 2 shown in Fig. 13. Here, in calculating the motor torque (Tm) based on Table 2, if the rotation speed of the motor 1 is equal to or lower than the predetermined rotation speed (ω2) shown in Fig. 8, a correction of Tm = Tm(ω-ω1) / (ω2-ω1) is made. After the calculation in S5, the mechanical braking torque (Tbmr) is set to 0 in S8, and then the above-mentioned S10 is performed.

[0040] On the other hand, if it is determined in S1 that a fault signal is present or if it is determined in S3 that regeneration is not possible, the process proceeds to S6, where the motor torque (Tm) is set to 0, and then the process proceeds to S9, where the mechanical braking torque (Tbmr) corresponding to the amount of operation of the regenerative brake operation means 8 is calculated based on Table 3 shown in Fig. 14. After the calculation in S9, the previously described S10 is performed.

[0041] Next, control (motor control) of the electric vehicle according to this embodiment will be described with reference to the flowcharts of FIGS. First, in S1, it is determined whether the regeneration system is normal based on the presence or absence of a fault signal, and if it is determined that a fault exists, the process proceeds to S15, where FCC is set to 9, and then power conversion control (S20) and inverter control (S21) are performed sequentially. Also, if it is determined that there is no fault signal in S1, it is determined in S2 whether the accelerator operation means 6 is being operated (whether the accelerator operation amount Ap is greater than 0), and if it is determined that the accelerator operation means 6 is being operated, it is determined in S3 whether the rotation speed of the motor 1 is greater than ω4 (see Figures 19 and 21).

[0042] If it is determined in S3 that the rotation speed of motor 1 is greater than ω4, it is determined in S4 whether the rotation speed of motor 1 is less than ω3 (see FIGS. 19 and 21), and if it is determined that the rotation speed of motor 1 is not less than ω3, the process proceeds to S7, where FCCNO is set to 1. If it is determined in S4 that the rotation speed of motor 1 is less than ω3, it is determined in S5 whether the state of charge (Soc2) of the second storage device 5 is less than a predetermined lower limit (see FIG. 25), and if it is determined that the state of charge (Soc2) of the second storage device 5 is less than the predetermined lower limit, the process proceeds to S8, where FCCNO is set to 2.

[0043] Furthermore, if it is determined in S3 that the rotation speed of motor 1 is not greater than ω4, it is determined in S6 whether or not the state of charge (Soc2) of second power storage device 5 is smaller than a predetermined intermediate value (see FIG. 25). If it is determined that the state of charge (Soc2) of second power storage device 5 is smaller than the predetermined intermediate value, or if it is determined in S5 that the state of charge (Soc2) of second power storage device 5 is not smaller than a predetermined lower limit value, the process proceeds to S9, where FCCNO is set to 3. If it is determined in S6 that the state of charge (Soc2) of second power storage device 5 is not smaller than the predetermined intermediate value (see FIG. 25), the process proceeds to S10, where FCCPNO is set to 4. After S7 to S10 are performed, the above-mentioned S20 and S21 are performed sequentially.

[0044] On the other hand, if it is determined in S2 that the accelerator operation means 6 is not being operated, then in S11 it is determined whether or not regeneration of the motor 1 is possible. This determination is made such that if the state of charge (Soc1) of the first power storage device 4 is equal to or less than a predetermined upper limit (see FIG. 24) and the motor rotation speed is equal to or greater than ω1 (see FIG. 8), then it is determined that regeneration of the motor 1 is possible. If it is determined in S11 that regeneration of the motor 1 is not possible, then the process proceeds to S15, where FCCNO=9 is set.

[0045] Furthermore, if it is determined in S11 that regeneration of the motor 1 is possible, it is determined in S12 whether the state of charge (Soc2) of the second power storage device 5 is equal to or greater than a predetermined upper limit (see FIG. 25), and if it is determined that the state of charge (Soc2) of the second power storage device 5 is equal to or greater than the predetermined upper limit, it is determined in S13 whether the rotation speed of the motor 1 is smaller than ω3. If it is determined in S13 that the rotation speed of the motor 1 is not smaller than ω3, the process proceeds to S16, where FCCNO=9 is set, and if it is determined in S13 that the rotation speed of the motor 1 is smaller than ω3, the process proceeds to S17, where FCCNO=6 is set.

[0046] Furthermore, if it is determined in S12 that the state of charge (Soc2) of the second power storage device 5 is not equal to or greater than a predetermined upper limit, it is determined in S14 whether the rotation speed of the motor 1 is greater than ω4 (see FIGS. 19 and 21), and if it is determined that the rotation speed of the motor 1 is greater than ω4, FCCNO=7 is set in S18, and if it is determined that the rotation speed of the motor 1 is not greater than ω4, FCCNO=8 is set in S19. After S15 to S19 are performed, the above-mentioned S20 and S21 are performed in sequence.

[0047] Here, the control in S20 is performed based on the control table in Fig. 18. The control content according to this control table will be explained below. When FCCNO=1, the switches S1, S2, and S3 of the semiconductor switch elements 10a, 10b, and 10d are turned off (the power converter 10 is turned off), and the switch Sa is turned on. Note that "capacitor used" in the control table means "second power storage device 5 is used."

[0048] When FCCNO=2, switches S1 and S2 of semiconductor switch elements 10a and 10b are duty controlled during power running, so that power converter 10 reduces the output voltage of the first power storage device, and switches S3 and Sa of semiconductor switch element 10d are turned off. When FCCNO=2, current control of inverter 2 is performed based on table A shown in FIG.

[0049] According to Table A, when the current control of the inverter 2 is performed by PWM control, the DC voltage of the inverter 2 can be controlled according to the rotation speed (ω) of the motor 1, and when the rotation speed of the motor 1 is equal to or lower than a predetermined rotation speed (ω3), the DC voltage of the inverter 2 is controlled to be lower as the rotation speed of the motor 1 decreases. Note that Table B, which will be described later, is also based on the assumption that the current control of the inverter 2 is performed by PWM control.

[0050] When FCCNO=3, switches S1, S2, and S3 of semiconductor switch elements 10a, 10b, and 10d are duty-controlled during power running, so that power converter 10 reduces the output voltage of the first power storage device and switch Sa is turned off. In this case as well, current control of inverter 2 is performed based on table A shown in FIG.

[0051] When FCCNO=4, switch S1 of semiconductor switch element 10a is turned off, and switches S2 and S3 of semiconductor switch elements 10b and 10d are duty controlled during power running, so that power converter 10 reduces the output voltage of the second power storage device and switch Sa is turned off. In this case as well, current control of inverter 2 is performed based on table A shown in FIG.

[0052] When FCCNO=5, switches S1, S2, and S3 of semiconductor switch elements 10a, 10b, and 10d are turned off (power converter 10 is turned off), and switch Sa is turned on. Note that when FCCNO=9, switches S1, S2, and S3 of semiconductor switch elements 10a, 10b, and 10d are turned off (power converter 10 is turned off), and switch Sa is turned off.

[0053] When FCCNO=6, the switches S1 and S2 of the semiconductor switch elements 10a and 10b are duty-controlled during regeneration, so that the power converter 10 boosts the inverter DC voltage, and the switches S3 and Sa are turned off. When FCCNO=6, the current control of the inverter 2 is performed based on table B shown in FIG.

[0054] According to Table B, when the current of inverter 2 is controlled by PWM control, the DC voltage of inverter 2 can be controlled according to the rotation speed (ω) of motor 1, as shown in Figure 20, and when the rotation speed of motor 1 is below a predetermined rotation speed (ω5), the DC voltage of inverter 2 is controlled to be lower the lower the rotation speed of motor 1.

[0055] When FCCNO=7, the switches S1, S2, and S3 of the semiconductor switch elements 10a, 10b, and 10d are duty-controlled during regeneration, so that the power converter 10 boosts the inverter DC voltage and the switch Sa is turned off. In this case, the current control of the inverter 2 is also performed based on table B shown in FIG.

[0056] When FCCNO=8, the switch S1 of the semiconductor switch element 10a is turned off, and the switches S2 and S3 of the semiconductor switch elements 10b and 10d are duty controlled during regeneration, so that the power converter 10 boosts the inverter DC voltage and the switch Sa is turned off. In this case as well, the current control of the inverter 2 is performed based on table B shown in FIG.

[0057] Furthermore, in the above embodiment, when applying Tables A and B, it is assumed that the current control of the inverter 2 is performed by PWM (pulse width modulation) control, but instead, the current control of the inverter 2 may be motor line voltage peak value dependent control. That is, PWM control is a control that changes the width (pulse width) of the switching frequency for a predetermined inverter DC voltage (changes the inverter current conduction rate), while motor line voltage peak value dependent control is a control that changes the inverter DC voltage itself depending on the peak value of the motor line voltage, as shown in Figures 21 to 23.

[0058] However, when inverter 2 current control is performed using motor line voltage peak value-dependent control, in Table A, as shown in FIG. 21, when the rotation speed of motor 1 is equal to or lower than a predetermined rotation speed (ω3), the DC voltage of inverter 2 is controlled according to the peak value of the motor line voltage. In addition, in Table B, the control shown in FIG. 22 is performed. FIG. 23 is a time chart showing an example of the switch operation of the inverter circuit and the operation of the motor line voltage and the fundamental wave of the motor line voltage when current control is performed using one of the tables in FIGS. 21 to 22 (when the inverter DC voltage and motor line voltage peak values are the same). In this time chart, the peak values of the inverter DC voltage (Vinv) and the fundamental wave of the motor line voltage match.

[0059] According to the electric vehicle of the above embodiment, when the motor 1 is powered, the output voltage of the first storage device 4 is stepped down by the power converter 10 and energy is supplied to the inverter 2 from the first storage device 4 and the second storage device 5. This allows the energy required during powering to be shared by a plurality of storage devices (in this embodiment, the first storage device 4 and the second storage device 5). In addition, since there is no limit to the step-down ratio of the power converter, the range between the lower limit and upper limit settings of the inverter DC voltage can be widened by stepping down the output voltage of the storage device to match the DC voltage setting of the inverter 2.

[0060] In particular, when adjusting the inverter DC voltage to a voltage lower than the voltage of the first storage device 4, the switches S1, S2, and S3 can be adjusted by duty control, so that the first storage device 4 and the second storage device 5 can share and supply the power running energy, and the current of the first storage device 4 can be reduced compared to when the same amount of power running energy is supplied by only the first storage device 4. Furthermore, when the power running energy is large, a large current needs to flow, but by sharing the power running energy between the first storage device 4 and the second storage device 5, the current of the first storage device 4 can be reduced and deterioration of the first storage device 4 can be suppressed.

[0061] Furthermore, the power converter 10 according to this embodiment has a function of stepping down during power running and a function of stepping up during regeneration, and during regeneration of the motor 1, it steps up the DC voltage of the inverter 2 and recovers energy in the first and second power storage devices 4 and 5. This allows the first and second power storage devices 4 and 5 to share and store the regenerative energy, and the current of the first power storage device 4 can be reduced compared to when the same amount of regenerative energy is stored in only the first power storage device 4. Furthermore, when the regenerative energy is large, a large current needs to flow, but by sharing the recovered energy between the first and second power storage devices 4 and 5, the current of the first power storage device 4 can be reduced and deterioration of the first power storage device 4 can be suppressed.

[0062] Furthermore, according to the present embodiment, the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 share the same ground connection switch 10b (i.e., the semiconductor switch element 10b serves as the ground connection switch 10b of the power converter for the first power storage device 4 and the power converter 10), thereby reducing the number of components connected to the circuit. Similarly, according to the present embodiment, the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 share the same reactor 10c, thereby reducing the number of components connected to the circuit.

[0063] However, as shown in Figures 27 to 29, the ground connection switches of the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 may be provided separately and not shared, and the reactors of the power converter 10 for the first power storage device 4 and the power converter 10 for the second power storage device 5 may be provided separately and not shared. In this case, for example, as shown in Figure 27, semiconductor switch elements 10a, 10b and reactor 10c of the power converter 10 are connected to the circuit on the first power storage device 4 side, and semiconductor switch elements 10e, 10f and reactor 10g of the power converter 10 are connected to the circuit on the second power storage device 5 side connected in parallel with the circuit on the first power storage device 4 side.

[0064] As shown in FIG. 29, by controlling the switches S1 and S2 constituting the semiconductor switch elements 10a and 10b of the power converter 10 in the circuit on the first storage device 4 side and the switches S4 and S5 constituting the semiconductor switch elements 10e and 10f of the power converter 10 in the circuit on the second storage device 5 side on / off or with duty control according to FCCNO, it is possible to supply and recover energy during power running and recovery in the same manner as in the above embodiment.

[0065] Furthermore, in this embodiment, charge and discharge control is performed so that the voltage (Vdc) of the first power storage device 4 is equal to or higher than the voltage (Vc) of the second power storage device 5, so that when the switch S3 is on, reverse current flow from the second power storage device 5 to the first power storage device 4 can be prevented. In other words, if charge and discharge control is not performed so that the voltage of the first power storage device 4 is equal to or higher than the voltage of the second power storage device 5, current will flow reversely from the second power storage device 5 to the first power storage device 4, and a separate switch for preventing reverse current is therefore required. In the embodiment shown in FIGS. 27 and 28, by turning off the switch Sa, reverse current flow from the second power storage device 5 to the first power storage device 4 can be prevented even when charge and discharge control is not performed so that the voltage of the first power storage device 4 is equal to or higher than the voltage of the second power storage device 5.

[0066] Furthermore, according to this embodiment, the state of charge of the second power storage device 5 can be determined based on the voltage of the second power storage device 5, and when the rotation speed of the motor 1 is equal to or lower than a predetermined rotation speed and the state of charge of the second power storage device 5 is equal to or higher than a predetermined intermediate value during power running of the motor 1, energy is supplied from the second power storage device 5 to the inverter 2. This allows the energy of the second power storage device 5 to be used preferentially, and the energy stored in the second power storage device 5 can be reduced more quickly than in a case where energy is supplied to the inverter 2 from both the first power storage device 4 and the second power storage device 5. As a result, for example, when regenerating on a long downhill slope after starting the vehicle, more regenerative energy can be stored in the second power storage device 5.

[0067] Furthermore, according to this embodiment, the state of charge of the second power storage device 5 can be determined based on the voltage of the second power storage device 5, and when the rotation speed of the motor 1 is equal to or lower than a predetermined rotation speed and the state of charge of the second power storage device 5 is equal to or lower than a predetermined upper limit during regeneration of the motor 1, the regenerative energy is recovered in the second power storage device 5, so that the regenerative energy can be stored down to a lower rotation speed than when the regenerative energy is stored in the first power storage device 4 and the second power storage device 5. The reason for this is that when the voltage of the first power storage device 4 is higher than the voltage of the second power storage device 5, the inverter DC voltage is low at low rotation speeds, so the voltage is boosted for regeneration, but there is a limit to the boost ratio of the power converter (for example, about 5 times), and therefore a lower voltage storage device allows regenerative energy to be stored down to a lower rotation speed.

[0068] Furthermore, when controlling the current of inverter 2, the DC voltage of inverter 2 can be controlled according to the rotation speed of motor 1, and when the rotation speed of motor 1 is below a predetermined rotation speed, the DC voltage of inverter 2 is controlled to be lower the lower the rotation speed of motor 1. Therefore, the DC voltage of inverter 2 can be lowered at low rotation speeds, the instantaneous power of the switch can be lowered, and switching loss at low rotation speeds can be reduced.

[0069] Furthermore, when the current of the inverter 2 is controlled and the rotation speed of the motor 1 is below a predetermined value, the DC voltage of the inverter 2 is controlled according to the peak value of the motor line voltage, so a fixed switching pattern that reduces low-order harmonics at about three times the fundamental frequency can be used. This allows the switching frequency to be 1 / 30 or less of the switching frequency of PWM control (duty control with constant inverter DC voltage), and switching losses can be reduced to 1 / 30 or less compared to PWM control.

[0070] Although the present embodiment has been described above, the present invention is not limited to this. For example, the first power storage device 4 may be another type of power storage device having higher capacity characteristics than the second power storage device 5, or the second power storage device 5 may be another type of power storage device having higher output characteristics than the first power storage device 4. In addition, the semiconductor switch elements may be IGBTs instead of MOSFETs. Furthermore, the present invention may be applied to vehicles that do not include a monitor 13, or to three-wheeled or four-wheeled vehicles such as buggies. [Industrial Applicability]

[0071] As long as the electric vehicle has a power converter that reduces the output voltage of the first storage device when the motor is powered and supplies energy from the first storage device and the second storage device to the inverter, the invention can also be applied to electric vehicles with different external shapes or with added functions. [Explanation of symbols]

[0072] 1 motor 2 inverters 3a Drive wheel mechanical brake 3b Driven wheel mechanical brake 4. First storage device (battery) 5 Second power storage device (capacitor) 6 Accelerator operation means 7 Mechanical brake operation means 8. Regenerative braking operation means 9 Brake Actuator 10 Power Converter 10a, 10b, 10d, 10e, 10f Semiconductor switching element (MOSFET) 10c, 10g reactor (coil) 11 ECU 12 Start switch 13 Monitor (auxiliary device) 16 Inverter control unit 17 Circuit control section 18 Mechanical brake control unit 19 Detection methods Ta drive wheel Tb driven wheel Ca smoothing capacitor Cb smoothing capacitor Vdc First storage device (battery) voltage Vc Second storage device (capacitor) voltage Vinv Inverter DC voltage V1 S2 terminal average voltage V2 S5 terminal average voltage

Claims

1. a motor capable of power running and regeneration; an inverter capable of converting direct current to alternating current; An electric vehicle having a first power storage device having high-capacity characteristics; a second power storage device having high-output characteristics; a power converter having a function of stepping down during power running; a circuit in which the power converter is connected to each of the first and second power storage devices so that the first and second power storage devices are connected in parallel; and wherein, when the motor is powered, the output voltage of the first power storage device is reduced by the power converter, and energy is supplied from the first power storage device and the second power storage device to the inverter, the power converter is capable of determining a power storage state of the second power storage device based on the voltage of the second power storage device, and when the motor is regenerating power, if the rotation speed of the motor is equal to or lower than a predetermined rotation speed and the power storage state of the second power storage device is equal to or lower than a predetermined upper limit value, the second power storage device recovers regenerated energy.

2. 2. The electric vehicle according to claim 1, wherein the power converter has a function of stepping down the DC voltage during power running and a function of stepping up the DC voltage during regeneration, and when the motor is regenerating, the power converter steps up the DC voltage of the inverter and recovers energy in the first power storage device and the second power storage device.

3. 3. The electric vehicle according to claim 1, wherein a state of charge of the second power storage device can be determined based on a voltage of the second power storage device, and wherein, when the motor is powered, if the rotation speed of the motor is equal to or lower than a predetermined rotation speed and the state of charge of the second power storage device is equal to or higher than a predetermined intermediate value, energy is supplied from the second power storage device to the inverter.

4. 4. The electric vehicle according to claim 1, wherein the power converter has a plurality of semiconductor switch elements, and during power running, high-speed switching of the switches of the semiconductor switch elements reduces the voltage of the first power storage device or the second power storage device, and during regeneration, high-speed switching of the switches of the semiconductor switch elements increases the voltage of the first power storage device or the second power storage device.

5. 5. The electric vehicle according to claim 1, wherein charging and discharging are controlled so that the voltage of the first power storage device becomes equal to or higher than the voltage of the second power storage device.

6. 6. The electric vehicle according to claim 1, wherein, during current control of the inverter, the DC voltage of the inverter can be controlled in accordance with the rotation speed of the motor, and when the rotation speed of the motor is equal to or lower than a predetermined rotation speed, the DC voltage of the inverter is controlled to be lower as the rotation speed of the motor becomes lower.

7. 7. The electric vehicle according to claim 1, wherein, during current control of the inverter, if the rotation speed of the motor is equal to or lower than a predetermined rotation speed, the DC voltage of the inverter is controlled in accordance with a peak value of a voltage between motor lines.

8. 8. The electric vehicle according to claim 1, wherein the first power storage device is a high-capacity lithium-ion battery or a high-capacity nickel-metal hydride battery, and the second power storage device is any one of a high-output lithium-ion battery, a high-output nickel-metal hydride battery, a lithium-ion capacitor, or an electric double layer capacitor.

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