Electric vehicle control method and electric vehicle control device

Abstract

Provided is a control method for an electric vehicle having a battery and an electric power train including an inverter and an electric motor, wherein, when the electric vehicle is stopped, the battery is warmed up using the heat of the electric power train, which is generated by causing a d-axis current to flow through the electric motor. In this electric vehicle control method, when the battery is warmed up, a d-axis current having a sign opposite to that of a d-axis current when the electric vehicle starts is set.

Description

Control method for electric vehicles, and control device for electric vehicles

[0001] The present invention relates to a control method and control device for electric vehicles.

[0002] JP2012-165526A discloses a control device for a vehicle's driving motor that sets the d-axis current value to facilitate battery warm-up when battery warm-up is required.

[0003] Electric vehicles sometimes use the heat generated by the inverter and motor to warm up the battery. When warming up the battery using the heat generated by the inverter and motor in this way, electric vehicles can accelerate battery warming by actively generating heat in the inverter and motor by increasing the so-called d-axis current. In particular, when an electric vehicle is stationary, it can generate heat in the inverter and motor while the motor is not rotating by only supplying d-axis current to the motor.

[0004] Thus, when a d-axis current is supplied to the motor while the electric vehicle is stationary, current flows through some of the multiple switching elements in the inverter. As a result, the temperature of some of the switching elements rises. Consequently, when the electric vehicle starts moving and it is necessary to supply current to the already heated switching elements, the torque output may be limited due to the heat resistance limit of the switching elements.

[0005] The present invention aims to provide a control method and control device for electric vehicles that, when warming up the battery using the heat from the inverter and electric motor while the electric vehicle is stopped, allows d-axis current to flow to the electric motor while making it less likely for the torque output when the electric vehicle starts to be restricted.

[0006] One aspect of the present invention is a control method for an electric vehicle having a battery and an electric powertrain including an inverter and an electric motor, wherein the battery is warmed up using the heat generated by the electric powertrain when a d-axis current is passed through the electric motor while the electric vehicle is stopped. In this electric vehicle control method, when warming up the battery, a d-axis current is set that has the opposite sign to the d-axis current when the electric vehicle starts moving.

[0007] Figure 1 is a block diagram showing the schematic configuration of an electric vehicle. Figure 2 is an explanatory diagram showing the circuit configuration of the electric powertrain. Figure 3 is a block diagram showing the configuration of the controller. Figure 4 is a block diagram showing the configuration of the current command calculation unit. Figure 5 is a block diagram showing the configuration of the warm-up current command calculation unit. Figure 6 is a flowchart showing the start of warm-up. Figure 7 is a flowchart showing the completion of warm-up. Figure 8 is a graph showing the relationship between the d-axis current and phase current for warm-up control. Figure 9 is an explanatory diagram showing the flow of phase current in the inverter when a negative d-axis current is flowed when θ = 0. Figure 10 is an explanatory diagram showing the flow of phase current in the inverter when a positive d-axis current is flowed when θ = 0. Figure 11 is an explanatory diagram showing the flow of phase current when the electric vehicle starts moving from a state of θ = 0. Figure 12 is a schematic graph showing the transition of phase current when a negative d-axis current is flowed in warm-up control when θ = 0, and then the electric vehicle starts moving. Figure 13 is a schematic graph showing the phase current transition when a positive d-axis current is applied during warm-up control when θ = 0, and then the electric vehicle starts moving. Figure 14 is a schematic graph showing the torque response during starting. Figure 15 is a flowchart related to warm-up control in the first modified example. Figure 16 is a flowchart related to warm-up control in the second modified example.

[0008] Embodiments of the present invention will be described below with reference to the drawings.

[0009] [Embodiment] Figure 1 is a block diagram showing a schematic configuration of an electric vehicle 100. The electric vehicle 100 is a vehicle capable of traveling by electric power, such as an electric vehicle or a hybrid vehicle. As shown in Figure 1, the electric vehicle 100 includes a battery 10, an electric powertrain 11, a cooling system 12, and a controller 13.

[0010] The battery 10 is a DC power source that stores electric power used for traveling of the electric vehicle 100 and the like. That is, the battery 10 supplies DC power to the electric powertrain 11. Also, the battery 10 is rechargeable. For example, the battery 10 is charged by an external power source or by regenerative power input from the electric powertrain 11. The battery 10 is constituted by, for example, a lithium ion battery.

[0011] Note that when the battery 10 is in a low temperature state, the power that can be input and output decreases. Therefore, when supplying power from the battery 10 in a low temperature state to the electric powertrain 11, or when charging the battery 10 in a warm state, it is necessary to warm up the battery 10 and increase the temperature of the battery 10 (hereinafter referred to as the battery temperature T). ｂａｔ to raise it.

[0012] In the present embodiment, in order to determine the necessity of warming up, a first temperature threshold T is determined for the battery temperature T according to the specific characteristics of the battery 10. That is, the low temperature state of the battery 10 means that the battery temperature T is lower than the first temperature threshold T (T < T), and the power that can be input and output is in a state of being lower than normal. And when the battery temperature T is lower than the first temperature threshold T (T < T), it is necessary to warm up the battery 10. The first temperature threshold T is determined in advance based on experiments or simulations or the like. ｂａｔ with respect to ｔｈ１ is defined. That is, the low temperature state of the battery 10 means that the battery temperature T ｂａｔ is lower than the first temperature threshold T ｔｈ１ (T ｂａｔ < T ｔｈ１ ), and the power that can be input and output is in a state where it has decreased more than usual. And when the battery temperature T ｂａｔ is lower than the first temperature threshold T ｔｈ１ (T ｂａｔ < T ｔｈ１ ), it is necessary to warm up the battery 10. The first temperature threshold T ｔｈ１ is determined in advance based on experiments or simulations or the like.

[0013] The electric powertrain 11 is a drive unit that generates driving force for the electric vehicle 100 using electricity supplied from the battery 10. Specifically, the electric powertrain 11 includes an inverter 14 and an electric motor 15.

[0014] The inverter 14 converts the DC power supplied from the battery 10 into AC power and supplies it to the motor 15. Furthermore, when the motor 15 generates regenerative power through so-called regenerative control, the inverter 14 converts the AC regenerative power input from the motor 15 into DC power and inputs it to the battery 10. As a result, the battery 10 is charged.

[0015] The electric motor 15 rotates using power input from the battery 10 via the inverter 14, and torque T is applied to its output shaft. ｍ This causes the torque T of the electric motor 15 to occur. ｍ The power is transmitted to the drive wheels 18 via the gearbox 16 (G / B) and drive shaft 17. This generates driving force in the electric vehicle 100. In addition, when the electric motor 15 rotates along with the drive wheels 18, the electric motor 15 generates regenerative power.

[0016] In this embodiment, the motor 15 is configured as, for example, a permanent magnet embedded type three-phase AC synchronous motor. Specifically, the motor 15 includes a rotor in which permanent magnets are embedded and a stator consisting of UVW three-phase windings. The rotor and stator are not shown in the illustration. Also, in this embodiment, the motor 15 is assumed to be a so-called reverse salient pole type as an example. For this reason, the motor 15 has a d-axis inductance L ｄ The q-axis inductance L ｑ (L) ｄ <L ｑ ). d-axis inductance L ｄ This is the inductance in the d-axis direction (the magnetization direction of the permanent magnet) in a Cartesian coordinate system (dq-axis coordinate system) that rotates with the rotor. Similarly, the q-axis inductance L is also represented. ｑ This is the inductance in the q-axis direction in the dq-axis coordinate system.

[0017] The cooling system 12 is a system that cools the battery 10 and the electric powertrain 11 by circulating coolant or the like to the battery 10, the electric powertrain 11, and a radiator (not shown), etc. Furthermore, the cooling system 12 can circulate the coolant or the like between the battery 10 and the electric powertrain 11. Therefore, when the battery 10 is in a low temperature state, the heat from the electric powertrain 11 is transported to the battery 10 using the coolant or the like, thereby lowering the battery temperature T ｂａｔ It can increase [something].

[0018] The controller 13 is a control device that comprehensively controls each part of the electric vehicle 100. The controller 13 is composed of, for example, one or more computers and is programmed to control the operation of each part at a predetermined control cycle.

[0019] In this embodiment, the controller 13 functions as a driving control device that controls the driving of the electric vehicle 100. Specifically, the controller 13 controls the accelerator operation amount A ｐｏ Based on the above, the torque T of the electric motor 15 ｍ By controlling this, driving force and braking force are generated in the electric vehicle 100.

[0020] Furthermore, in this embodiment, the controller 13 functions as a warm-up control device that warms up the battery 10 in a low-temperature state using the heat from the electric powertrain 11. Specifically, when the electric vehicle 100 is stopped and the battery 10 is in a low-temperature state, the controller 13 supplies the electric motor 15 with a d-axis current i ｄ By flowing this fluid, the electric powertrain 11 (i.e., the inverter 14 and the electric motor 15) is heated without rotating the electric motor 15. The controller 13 then uses the cooling system 12 to transport the heat generated in the electric powertrain 11 to the battery 10, thereby lowering the battery temperature T ｂａｔ The d-axis current i of the electric vehicle 100 is increased. If the electric vehicle 100 starts running despite the battery 10 being at a low temperature, the controller 13 will increase the d-axis current i of the electric motor 15. ｄ By increasing the torque T of the electric motor 15, ｍWhile maintaining the same performance, the heat generated by the electric powertrain 11 can be increased. However, in this embodiment, the controller 13 generally warms up the battery 10 when the electric vehicle 100 is stopped.

[0021] Figure 2 is an explanatory diagram showing the circuit configuration of the electric powertrain 11. As shown in Figure 2, the electric motor 15 has windings (stator windings) for each of the U, V, and W phases.

[0022] The electric motor 15 is equipped with a rotational position detector 21 for detecting the rotational position of the rotor. The rotational position detector 21 is, for example, a resolver. The controller 13 receives a rotational position detection signal (hereinafter referred to as the rotational position detection signal S) from the rotational position detector 21. ｒｏｔ The controller 13 can acquire the rotation position detection signal S as needed. ｒｏｔ Based on this, the electrical angle θ and electrical angular velocity ω of the rotor are detected as appropriate. Note that when the electric vehicle 100 is stopped, the rotation of the electric motor 15 is stopped. Therefore, when the electric vehicle 100 is stopped, the electrical angle θ is a constant value indicating the rotor's stopping position. Also, the electrical angular velocity ω is zero.

[0023] A current sensor 22 is provided between the inverter 14 and the motor 15. Therefore, the controller 13 detects the current flowing through the windings of each phase (hereinafter referred to as phase current i). ｕｖｗ The phase current i can be detected as needed using the current sensor 22. ｕｖｗ i is the U-phase current flowing through the U-phase winding. ｕ , V-phase current i flowing through the V-phase winding ｖ , and the W-phase current i flowing through the W-phase winding. ｗ It is a general term for [something].

[0024] The inverter 14 includes a smoothing capacitor 23 provided at the input terminal connected to the battery 10, and a bridge circuit configured using a plurality of switching elements (UP-WN). A voltage sensor 24 is also provided near the smoothing capacitor 23 (at the input terminal of the inverter 14). Therefore, the controller 13 uses the voltage sensor 24 to determine the DC voltage V input from the battery 10 to the inverter 14. ｄｃIt can be obtained as appropriate.

[0025] Each switching element (UP to WN), together with a freewheeling diode, constitutes an arm of each phase. Specifically, UP is a switching element that constitutes the upper arm of the U phase, and UN is a switching element that constitutes the lower arm of the U phase. VP is a switching element that constitutes the upper arm of the V phase, and VN is a switching element that constitutes the lower arm of the V phase. Similarly, WP is a switching element that constitutes the upper arm of the W phase, and WN is a switching element that constitutes the lower arm of the W phase. Below, the current flowing through the upper arm of the U phase is defined as i ＵＰ This is expressed as i, and the current flowing through the lower arm of the U phase is i ＵＮ This is expressed as follows. Also, the current flowing through the V-phase upper arm is i ＶＰ This is expressed as i, and the current flowing through the lower arm of the V phase is i ＶＮ This is expressed as follows. Similarly, the current flowing through the W-phase upper arm is i ＷＰ This is expressed as i, and the current flowing through the W-phase lower arm is i ＷＮ It is represented as follows.

[0026] Each switching element (UP to WN) receives a drive signal D generated by the controller 13. ｕｕ ＊ -D ｗｌ ＊ = (D ｕｕ ＊ , D ｕｌ ＊ , D ｖｕ ＊ , D ｖｌ ＊ , D ｗｕ ＊ , D ｗｌ ＊ ) switches according to the drive signal D. That is, the on / off state of each switching element (UP to WN) is controlled by the drive signal D. ｕｕ ＊ ~D ｗｌ ＊ It can be switched by [this]. Note that the drive signal for UP is D ｕｕ ＊ Therefore, the drive signal for UN is D ｕｌ ＊ The drive signal for VP is D ｖｕ ＊ Therefore, the drive signal for VN is D ｖｌ＊ And the drive signal for WP is D ｗｕ ＊ And the drive signal D of WN ｗｌ ＊ Therefore, in the following, unless there is a particular need to distinguish between them, the drive signal D of each switching element (UP to WN) is used. ｕｕ ＊ ~D ｗｌ ＊ Put them together into D ＊ It is sometimes abbreviated as follows:

[0027] Battery 10 has a battery temperature T ｂａｔ The controller 13 also includes a battery state sensor 25 that detects the state of the battery 10, such as the State of Charge (SOC). Therefore, the controller 13 uses the battery state sensor 25 to determine the battery temperature T as needed. ｂａｔ And SOC and other parameters can be acquired as appropriate. SOC is a parameter that represents the charge state (charge rate) of the battery 10.

[0028] The controller 13 uses an accelerator opening sensor (not shown) to appropriately control the accelerator operation amount A. ｐｏ The controller 13 can acquire the gradient ψ of the road surface on which the electric vehicle 100 is located as appropriate. The controller 13 can determine the gradient ψ using, for example, the location information of the electric vehicle 100 and the map data of the navigation system. The controller 13 can also determine the gradient ψ using a gradient sensor (or acceleration sensor, etc.) not shown.

[0029] Figure 3 is a block diagram showing the configuration of the controller 13. It includes a torque command calculation unit 31, a warm-up requirement determination unit 32, a current command calculation unit 33, a current control unit 34, a coordinate transformation unit 35, a PWM control unit 36, a rotation position detection unit 37, and a coordinate transformation unit 38, etc.

[0030] The torque command calculation unit 31 calculates the accelerator operation amount A ｐｏ Based on the above, the torque command T ｍ ＊ Calculate the torque command T. ｍ ＊ The torque T of the electric motor 15ｍ is the command (target value) for this. In this embodiment, the torque command calculation unit 31 uses the accelerator operation amount A ｐｏ and the electrical angular velocity ω, and a torque map associating the torque command T ｍ ＊ is provided in advance. Therefore, the torque command calculation unit 31 refers to this torque map to obtain the torque command T corresponding to the accelerator operation amount A ｐｏ and the electrical angular velocity ω ｍ ＊ is calculated. The torque map is determined in advance based on experiments or simulations, etc. When the electric vehicle 100 is stopped, both the accelerator operation amount A ｐｏ and the electrical angular velocity ω are zero. Therefore, the torque command T ｍ ＊ also becomes zero.

[0031] The warm-up necessity determination unit 32 determines whether it is necessary to warm up the battery 10, that is, determines the necessity of warm-up control, based on the battery temperature T ｂａｔ . Specifically, when the battery temperature T ｂａｔ is lower than the first temperature threshold T ｔｈ１ and the power that can be input and output by the battery 10 has decreased, the warm-up necessity determination unit 32 determines that it is necessary to warm up the battery 10. On the other hand, when the battery temperature T ｂａｔ is higher than or equal to the first temperature threshold T ｔｈ１ and the power that can be input and output by the battery 10 is at the original level as planned, the warm-up necessity determination unit 32 determines that it is not necessary to warm up the battery 10. The warm-up necessity determination unit 32 inputs a warm-up command C ｗａｒｍ indicating the result of the determination to the current command calculation unit 33. The warm-up command C ｗａｒｍ indicates either that warm-up control is necessary or not.

[0032] In principle, the warm-up requirement determination unit 32 determines whether warm-up control is necessary when the power switch (not shown) is ON and the electric vehicle 100 is in an operational state. However, the warm-up requirement determination unit 32 may also determine whether warm-up control is necessary at a set time reserved in advance by the driver or other user's settings. In this way, when the warm-up requirement determination unit 32 determines that warm-up control is necessary at a predetermined set time, the controller 13 will execute warm-up control even if the driver or other user does not turn on the power switch.

[0033] The current command calculation unit 33 calculates the torque command T when the electric vehicle 100 is running. ｍ ＊ DC voltage V ｄｃ Based on the electrical angular velocity ω, the motor 15 receives a torque command T ｍ ＊ Torque T corresponding to ｍ Output the dq axis current command i ｄｑ ＊ The dq axis current command i is calculated. ｄｑ ＊ is the d-axis current i ｄ The command (target value) for the d-axis current command i ｄ ＊ And the q-axis current i ｑ The command (target value) for the q-axis current command i ｑ ＊ This is a general term for the following. In this embodiment, the current command calculation unit 33 calculates the torque command T ｍ ＊ DC voltage V ｄｃ , and the electrical angular velocity ω and the dq-axis current command i ｄｑ ＊ It has a dq-axis current command map (not shown) that has been pre-associated with the dq-axis current command map based on experiments or simulations. Therefore, the current command calculation unit 33 refers to this dq-axis current command map to calculate the torque command T ｍ ＊ DC voltage V ｄｃ , and the dq axis current command i corresponding to the electrical angular velocity ω ｄｑ ＊ Perform the calculation.

[0034] Furthermore, when the electric vehicle 100 is running, a warm-up command C indicates that warm-up control is necessary. ｗａｒｍ If this is input, the current command calculation unit 33 will, for example, calculate the q-axis current i ｑ Maintain the battery temperature T ｂａｔ The d-axis current i ｄ The dq axis current command i increases ｄｑ ＊ This allows for adjustment of the torque T of the electric motor 15. ｍ While maintaining the same temperature, the amount of heat generated by the electric powertrain 11 increases. As a result, the warming up of the battery 10 is accelerated.

[0035] The electric vehicle 100 is stopped, and the torque command T ｍ ＊ When it is zero, the dq axis current command i is usually ｄｑ ＊ It is also zero. However, when the electric vehicle 100 is stopped, a warm-up command C indicating that warm-up control is necessary is issued. ｗａｒｍ If this is input, the current command calculation unit 33 will determine the battery temperature T ｂａｔ , and based on the electrical angle θ, a dq axis current command i for warm-up control. ｄｑ ＊ Calculate the dq axis current command i for warm-up control. ｄｑ ＊ is the q-axis current i ｑ While keeping it at zero, the d-axis current i ｄ This is a command to supply only this current to the motor 15. Therefore, the current command calculation unit 33 receives the q-axis current command i ｑ ＊ Set to zero, and the d-axis current command i ｄ ＊ Battery temperature T ｂａｔ Set according to the instructions.

[0036] However, when the electric vehicle 100 is stopped and the electric motor 15 has stopped rotating, the d-axis current i ｄ The direction in which the current flows, i.e., the d-axis current i ｄ The sign σ can be arbitrarily selected from two directions. For this reason, in this embodiment, as an example, the current command calculation unit 33 uses the electrical angle θ (rotor stopping position), the road surface gradient ψ, and the battery temperature T as parameters. ｂａｔBased on the above, the d-axis current i ｄ Set the direction (sign σ) in which the fluid flows.

[0037] The current control unit 34 controls the dq axis current command i ｄｑ ＊ and dq axis current i ｄｑ Based on this, the dq axis voltage command v ｄｑ ＊ The dq axis current i is calculated. ｄｑ This is the d-axis current i that actually flows through the electric motor 15. ｄ and q-axis current i ｑ This is the detected value. dq axis voltage command v ｄｑ ＊ is the dq axis current i ｄｑ The dq axis current command i ｄｑ ＊ It is determined to match or follow the. In this embodiment, the current control unit 34 controls the dq-axis voltage command v by PI (Proportional Integral) control as shown in equation (1) below. ｄｑ ＊ Calculate K. ｐｄ This is the d-axis proportional gain, and K ｉｄ is the d-axis integral gain. Similarly, K ｐｑ This is a q-axis proportional gain, and K ｉｑ is the q-axis integral gain, and φ is the permanent magnet flux linkage number.

[0038]

[0039] The coordinate transformation unit 35 performs a coordinate transformation from the dq axis coordinate system to the UVW three-phase coordinate system based on the electrical angle θ, thereby generating the dq axis voltage command v ｄｑ ＊ From three-phase voltage command v ｕｖｗ ＊ The three-phase voltage command v is calculated. ｕｖｗ ＊ This is the U-phase voltage command v ｕ ＊ V-phase voltage command v ｖ ＊ , and W-phase voltage command v ｗ ＊ It is a general term for [something].

[0040] The PWM control unit 36 ​​controls the three-phase voltage command using so-called PWM (Pulse Width Modulation) control. ｖｕｖｗ ＊ Based on this, the drive signal D of each switching element (UP-WN) ＊ = D ｕｕ ＊ ~D ｗｌ ＊ This generates a drive signal D*. According to this drive signal D*, each switching element (UP-WN) is switched, and the motor 15 receives a dq axis current command i ｄｑ ＊ dq axis current i corresponding to ｄｑ A current flows. As a result, when the electric vehicle 100 is running, the electric motor 15 receives the torque command T. ｍ ＊ Torque T corresponding to ｍ It outputs the following. Also, when warming up the battery 10 while the electric vehicle 100 is stopped, the electric motor 15 remains stopped rotating, and the d-axis current command i ｄ ＊ d-axis current i corresponding to ｄ The inverter 14 and motor 15 generate heat when power is supplied. The heat generated by the inverter 14 and motor 15 is then transported, which accelerates the warming up of the battery 10.

[0041] The rotation position detection unit 37 receives the rotation position detection signal S. ｒｏｔ Based on this, the electrical angle θ and electrical angular velocity ω are detected. The electrical angle θ is used in the current command calculation unit 33, the coordinate transformation unit 35, and the coordinate transformation unit 38. The electrical angular velocity ω is used in the torque command calculation unit 31 and the current command calculation unit 33, as described above.

[0042] The coordinate transformation unit 38 performs a coordinate transformation from the three-phase coordinate system to the dq-axis coordinate system based on the electrical angle θ, thereby determining the phase current i ｕｖｗ From the dq axis current i ｄｑ This calculates the dq axis current i. ｄｑ As mentioned above, the detected value is used in the PI control in the current control unit 34.

[0043] Figure 4 is a block diagram showing the configuration of the current command calculation unit 33. As shown in Figure 4, the current command calculation unit 33 includes a driving current command calculation unit 41, a warm-up current command calculation unit 42, and a selection unit 43.

[0044] The driving current command calculation unit 41 calculates the torque command T when the electric vehicle 100 is running. ｍ ＊ DC voltage V ｄｃ , and based on the electrical angular velocity ω, the dq axis current command i for driving ｄｑ１ ＊ The dq axis current command i for driving is calculated. ｄｑ１ ＊ Torque command T is given to the electric motor 15. ｍ ＊ Torque T corresponding to ｍ The dq axis current command i that outputs ｄｑ ＊ The driving current command calculation unit 41 calculates the torque command T by referring to the dq axis current command map. ｍ ＊ DC voltage V ｄｃ , and the dq axis current command i for driving, according to the electrical angular velocity ω. ｄｑ１ ＊ Perform the calculation.

[0045] The warm-up current command calculation unit 42 calculates the dq-axis current command i for warm-up control based on the electrical angle θ (rotor stopping position) when the electric vehicle 100 is stopped. ｄｑ２ ＊ The following is calculated: dq axis current command i for warm-up control. ｄｑ２ ＊ The stopped motor 15 receives a d-axis current i ｄ By applying this current, the rotation of the motor 15 is stopped, while the inverter 14 and the motor 15 are heated up by the dq-axis current command i. ｄｑ ＊ Furthermore, the warm-up current command calculation unit 42 calculates the electrical angle θ (rotor stopping position), the road surface gradient ψ, and the battery temperature T. ｂａｔ Based on the above, the d-axis current i should be supplied to the electric motor 15 for warming up the battery 10. ｄ Set the direction (sign σ).

[0046] The selection unit 43 is, for example, a torque command Tｍ ＊ and warm-up command C ｗａｒｍ Based on this, the dq axis current command i for driving ｄｑ１ ＊ or dq axis current command i for warm-up control ｄｑ２ ＊ Select one of the following and final dq axis current command i ｄｑ ＊ It outputs as follows: Specifically, the torque command T ｍ ＊ When the value is greater than zero and the electric vehicle 100 is running, the selection unit 43 sets the dq axis current command i for running. ｄｑ１ ＊ The final dq axis current command i ｄｑ ＊ It outputs as follows: and the torque command T ｍ ＊ When the value is zero and the electric vehicle 100 is stopped, warm-up command C ｗａｒｍ When the warm-up control is being commanded, the selection unit 43 commands the dq axis current i for warm-up control. ｄｑ２ ＊ The final dq axis current command i ｄｑ ＊ Output as follows.

[0047] Figure 5 is a block diagram showing the configuration of the warm-up current command calculation unit 42. As shown in Figure 5, the warm-up current command calculation unit 42 includes a current amount setting unit 51, a starting load estimation unit 52, a starting current specification unit 53, a current direction setting unit 54, and a current command setting unit 55.

[0048] The current setting unit 51 is set to the battery temperature T ｂａｔ Based on this, the d-axis current i is supplied for warm-up control. ｄ The magnitude (hereinafter simply referred to as current quantity | i) ｄ The current setting unit 51 sets the battery temperature T. ｂａｔ The lower the current |i ｄ Set | to a large value. More specifically, the current setting unit 51 sets the first temperature threshold T ｔｈ１ and battery temperature T ｂａｔ The larger the difference, the greater the current quantity |i ｄ Increase the |. Also, the current setting unit 51 is set to the battery temperature Tｂａｔ The higher the current |i ｄ Set | to a large value. More specifically, the current setting unit 51 sets the battery temperature T ｂａｔ The first temperature threshold T ｔｈ１ The closer it gets, the greater the current |i ｄ Set or change | to a small value. Therefore, the warm-up control will cause the battery temperature T ｂａｔ When it increases, the current |i ｄ The | symbol becomes smaller.

[0049] In this embodiment, the battery temperature T ｂａｔ The second temperature threshold T predetermined ｔｈ２ This concludes the explanation, and the first temperature threshold T ｔｈ１ When it approaches, the current setting unit 51 sets the d-axis current i for warm-up control. ｄ Current quantity | i ｄ | Reduce. Note that the second temperature threshold T ｔｈ２ This is set in advance based on experiments or simulations, etc. However, the second temperature threshold T ｔｈ２ The first temperature threshold T ｔｈ１ Set to a value lower than (T ｔｈ２ <T ｔｈ１ ).

[0050] The starting load estimation unit 52 estimates the load on the electric motor 15 when the electric vehicle 100 starts moving. Specifically, the starting load estimation unit 52 estimates the load on the electric motor 15 when starting and compares that load with a load threshold set in advance based on experiments or simulations.

[0051] In this embodiment, for simplicity, the electric vehicle 100 is assumed to start in the forward direction. Also, in this embodiment, as an example, the starting load estimation unit 52 estimates that the road surface gradient ψ represents the load on the electric motor 15 at the time of starting. The starting load estimation unit 52 then considers the gradient ψ and the gradient threshold ψ. ｔｈ (Load threshold) By comparing, it is estimated whether a large load is applied to the electric motor 15 at startup. That is, the gradient ψ is the gradient threshold ψ ｔｈ When it is greater than, the starting load estimation unit 52 estimates that the electric vehicle 100 will have a relatively large torque T when it starts. ｍThe output required is such that a large load is placed on the motor 15. On the other hand, the gradient ψ is the gradient threshold ψ. ｔｈ When the following conditions are met, the starting load estimation unit 52 estimates that the torque T is not large enough when the electric vehicle 100 starts moving. ｍ No output is required, and it is estimated that the load on the motor 15 is relatively small. Gradient threshold ψ ｔｈ These are predetermined based on experiments or simulations.

[0052] The starting load estimation unit 52 may estimate the load on the electric motor 15 when the electric vehicle 100 starts moving, based on parameters other than the road surface gradient ψ. For example, if the electric vehicle 100 is towing another vehicle, the load on the electric motor 15 at startup is large. Therefore, if the use of a towing device (not shown) is detected, the starting load estimation unit 52 can estimate that the load on the electric motor 15 at startup is large, and if the use of a towing device is not detected, it can estimate that the load on the electric motor 15 at startup is small. Also, if the weight of the electric vehicle 100 has increased due to loading, etc., the load on the electric motor 15 at startup is large. Therefore, if the weight of the electric vehicle 100 is greater than a predetermined weight threshold, the starting load estimation unit 52 can determine that the load on the electric motor 15 at startup is large, and if the weight of the electric vehicle 100 is less than or equal to the weight threshold, it can estimate that the load on the electric motor 15 at startup is small. Therefore, the starting load estimation unit 52 can estimate the load on the electric motor 15 at the time of starting based on the road surface gradient ψ, whether or not a traction device is used, the weight of the electric vehicle 100, or a combination thereof. In this embodiment, for simplicity, it is assumed that a traction device is not used and the weight of the electric vehicle 100 has not increased, and the starting load estimation unit 52 estimates the load on the electric motor 15 at the time of starting based on the road surface gradient ψ.

[0053] The starting current identification unit 53 identifies the current flowing through the inverter 14 and the motor 15 when the electric vehicle 100 starts moving, based on the electrical angle θ (the stopping position of the rotor). Specifically, the starting current identification unit 53 identifies the switching element (hereinafter referred to as the maximum current element) through which the maximum phase current flows in the inverter 14 when the electric vehicle 100 starts moving.

[0054] The element with the highest current is uniquely determined by the electrical angle θ (the stopping position of the rotor) and the predetermined characteristics (structure) of the electric motor 15, as described below.

[0055] First, the torque T output by the electric motor 15 ｍ In general, it is expressed by the following equation (2), using the number of pole pairs p and the magnetic flux Φ of the magnet. Φi in the first term ｑ This is the so-called magnetic torque, and the second term (L ｄ -L ｑ ) i ｄ i ｑ This is what is known as reluctance torque. And in this embodiment, the electric motor 15 is of the reverse salient pole type, L ｑ > L ｄ Therefore, the expression in parentheses in equation (2) is negative. For this reason, when the electric vehicle 100 starts up, it efficiently generates a high torque T. ｍ In order to obtain the output, in principle, a negative d-axis current i ｄ (i ｄ <0) Current command i on the dq axis so that it flows ｄｑ ＊ This will be set.

[0056]

[0057] And, for example, if the rotor's stopping position is θ = 0 [deg], then the negative d-axis current i ｄ When flowing, the phase current i is applied to VP, PN, and WN. ｕｖｗ A current flows. Specifically, the phase current i ｕｖｗ The flow is as follows: V-phase current i from battery 10 to VP (V-phase upper arm) ｖ The current flows in, and the U-phase current i passes through the PN (U-phase lower arm). ｕ And the W-phase current i passing through WN (W-phase lower arm) ｗThe current is distributed and returns to the battery 10. Therefore, the switching element through which the maximum phase current flows is VP. Consequently, when θ = 0, the starting current identification unit 53 can identify VP as the maximum current element. Depending on the electrical angle θ, two of the switching elements (UP-WN) may simultaneously become the maximum current elements.

[0058] The current direction setting unit 54 takes into account the maximum current element identified by the starting current identification unit 53, the estimated result by the starting load estimation unit 52, and the battery temperature T ｂａｔ Based on this, the d-axis current i is supplied to the motor 15 for warm-up control. ｄ Set the direction (sign σ).

[0059] Specifically, the current direction setting unit 54, in principle, sets the phase current i to the maximum current element. ｕｖｗ No current flows, and the switching element paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. The switching element paired with the maximum current element is the other switching element that constitutes the same phase leg as the maximum current element.

[0060] For example, when the rotor's stopping position is θ = 0, the element with the highest current is VP (V-phase upper arm), so the current direction setting unit 54 sets the V-phase current i to VN (V-phase lower arm). ｖ The d-axis current command i ｄ ＊ The sign σ is set to a negative value (σ = -1). As a result, in warm-up control, the d-axis current i is in the opposite direction to when the electric vehicle 100 starts moving. ｄ A negative d-axis current i flows when the electric vehicle 100 starts. ｄ (i ｄ Since a current of <0 flows, a positive d-axis current i is generated during warm-up control. ｄ (i ｄ >0) is played.

[0061] The current direction setting unit 54 takes into account the estimated result by the starting load estimation unit 52 and the battery temperature T. ｂａｔ Accordingly, the above principle of d-axis current i ｄThe direction (sign σ) of the function may be changed.

[0062] First, the current direction setting unit 54 sets the d-axis current i according to the estimation result by the starting load estimation unit 52. ｄ Change the orientation (sign σ) setting.

[0063] Specifically, when the starting load estimation unit 52 determines that the load on the motor 15 is large at the time of starting, the current direction setting unit 54 sets the phase current i to the maximum current element, as per the above principle. ｕｖｗ No current flows, and the switching element paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. That is, the phase current i flowing through the maximum current element at startup. ｕｖｗ When the current is large and there is a high possibility that the heat generated by the maximum current element will be large, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ No current flows, and the switching element paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ Set the sign σ.

[0064] On the other hand, when the starting load estimation unit 52 determines that the load on the motor 15 is small at the time of starting, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. That is, the phase current i flowing through the maximum current element at startup. ｕｖｗ When the current is small and it is not expected that the heat generated by the maximum current element will be very large, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. This results in the torque T at startup. ｍ The responsiveness will improve.

[0065] Next, the current direction setting unit 54 sets the battery temperature T ｂａｔ Accordingly, the d-axis current i ｄ Change the setting for the direction (sign σ).

[0066] Specifically, battery temperature Tｂａｔ The second temperature threshold T ｔｈ２ If it is lower than the above principle, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ No current flows, and the switching element paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. That is, the battery temperature T ｂａｔ The current is low, and the current amount |i is used for warm-up control. ｄ | is large d-axis current i ｄ When flowing current, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ No current flows, and the switching element paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ Set the sign σ.

[0067] Meanwhile, battery temperature T ｂａｔ The second temperature threshold T ｔｈ２ If the above conditions are met, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. That is, the current quantity |i| for warm-up control. ｄ | is a relatively small d-axis current i ｄ When flowing current, the current direction setting unit 54 sets the phase current i to the maximum current element. ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The sign σ is set. This results in the torque T at startup. ｍ The responsiveness will improve.

[0068] The current command setting unit 55 sets the d-axis current i set by the current direction setting unit 54. ｄ The sign σ and the current amount |i set by the current amount setting unit 51. ｄ | According to this, the dq axis current command i for warm-up control ｄｑ２ ＊ This is set. Therefore, the dq axis current command i for warm-up control is set. ｄｑ２ ＊ The sign σ and the current |i ｄ | has a d-axis current command i ｄ２ ＊ The q-axis current command i is set to zero.ｑ ＊ It is composed of and . That is, i ｄｑ２ ＊ = (i ｄ２ ＊ , i ｑ２ ＊ ) = (σ | i ｄ |, 0)

[0069] The operation of the warm-up control in the electric vehicle 100 configured as described above will be explained below.

[0070] Figure 6 is a flowchart showing the process up to the start of warm-up. However, it is assumed that the electric vehicle 100 is stationary. As shown in Figure 6, in step S10, the controller 13 sets the battery temperature T ｂａｔ The road surface gradient ψ is obtained. In step S11, the warm-up requirement determination unit 32 determines the battery temperature T ｂａｔ and the first temperature threshold T ｔｈ１ The system compares these values ​​to determine whether warm-up control is necessary.

[0071] In step S11, the battery temperature T ｂａｔ The first temperature threshold T ｔｈ１ Therefore, when it is not necessary to warm up the battery 10, the warm-up necessity determination unit 32 issues a warm-up command C indicating that warm-up control is unnecessary. ｗａｒｍ This setting is applied. Therefore, all steps for warm-up control, as described later, are skipped. Consequently, warm-up control is not performed.

[0072] On the other hand, in step S11, the battery temperature T ｂａｔ The first temperature threshold T ｔｈ１ When the temperature is lower than and the battery 10 needs to be warmed up, the warm-up necessity determination unit 32 issues a warm-up command C indicating that warm-up control is necessary. ｗａｒｍ The settings are configured. Then, the control proceeds to step S12.

[0073] In step S12, the current setting unit 51 sets the battery temperature T ｂａｔ Accordingly, the d-axis current i supplied to the motor 15 for warm-up control. ｄ Current quantity | i ｄ Set |.

[0074] In step S13, the starting load estimation unit 52 estimates the load on the electric motor 15 when the electric vehicle 100 starts moving. In this embodiment, the degree of the load on the electric motor 15 at the time of starting is estimated based on the road surface gradient ψ.

[0075] In step S13, the gradient ψ is equal to the gradient threshold ψ. ｔｈ If it is greater than, a large torque T is generated when the electric vehicle 100 starts. ｍ The output is required, and it is estimated that a large load will be placed on the motor 15. In this case, the control proceeds to step S14. Steps S14, and steps S15 to S17 following step S14, are performed when a large load is placed on the motor 15 at startup, and a large phase current i is applied to a specific switching element (i.e., the maximum current element). ｕｖｗ This is a step that is executed when it is expected that a certain amount of data will flow.

[0076] On the other hand, in step S13, the gradient ψ becomes the gradient threshold ψ ｔｈ The following is true, and the torque T is not so large when the electric vehicle 100 starts up. ｍ No output is required, and it is estimated that the load on the motor 15 is relatively small. In this case, the control proceeds to step S18. Steps S18, and steps S19 to S21 following step S18, are performed when the load on the motor 15 is small at startup, and even with a specific switching element (maximum current element), the phase current i ｕｖｗ This step is performed when the expected value is relatively small.

[0077] First, a large load is placed on the electric motor 15 during starting, resulting in a large phase current i on a specific switching element. ｕｖｗ If it is expected that the flow will occur (step S13: YES), the control proceeds as follows.

[0078] In step S14, the starting current identification unit 53 identifies the maximum current element through which the maximum phase current flows at the time of starting, based on the electrical angle θ and the characteristics of the electric motor 15.

[0079] Then, in step S15, the current direction setting unit 54 sets the d-axis current i for warm-up control, for example. ｄWhen the sign σ is set to σ = -1, it is confirmed whether or not the phase current flows through the specified maximum current element. When it is determined in step S15 that the phase current flows through the maximum current element when σ is set to -1, the process proceeds to step S16, and the current direction setting unit 54 sets the d-axis current i to be passed for warm-up control. ｄ The sign σ of is set to σ = +1.

[0080] On the other hand, when it is determined in step S15 that the phase current does not flow through the maximum current element when σ is set to -1, the process proceeds to step S17, and the current direction setting unit 54 sets the sign σ of the d-axis current i to be passed for warm-up control to σ = -1. ｄ The sign σ of is set to σ = -1.

[0081] That is, when a large load is applied to the motor 15 at the time of starting and a large phase current i is expected to flow through a specific switching element, the current direction setting unit 54 sets the sign σ of the d-axis current i to be passed for warm-up control so as to be opposite to the d-axis current i flowing at the time of starting. For this reason, in the warm-up control, no phase current flows through the maximum current element. ｕｖｗ is expected to flow, the current direction setting unit 54 sets the sign σ of the d-axis current i to be passed for warm-up control so as to be opposite to the d-axis current i flowing at the time of starting. ｄ The direction of ｄ For this reason, in the warm-up control, no phase current flows through the maximum current element. ｄ is set.

[0082] Next, when the load of the motor 15 at the time of starting is small and it is expected that the phase current i is relatively small even in a specific switching element (step S13: NO), the control proceeds as follows. ｕｖｗ is relatively small (step S13: NO), the control proceeds as follows.

[0083] In step S18, the starting current specifying unit 53 specifies the maximum current element through which the maximum phase current flows at the time of starting based on the electrical angle θ and the characteristics of the motor 15. This is the same as in step S14.

[0084] Then, in step S19, the current direction setting unit 54 checks whether or not the phase current flows through the specified maximum current element when the sign σ of the d-axis current i to be passed for warm-up control, for example, is set to σ = -1. This is the same as in step S15. ｄ The sign σ of is set to σ = -1.

[0085] However, when it is determined in step S19 that the phase current flows through the maximum current element when σ is set to -1, the process proceeds to step S20, and the current direction setting unit 54 sets the sign σ of the d-axis current i ｄ to be flowed for warm-up control to σ = -1. On the other hand, when it is determined in step 19 that the phase current does not flow through the maximum current element when σ is set to -1, the process proceeds to step S21, and the current direction setting unit 54 sets the sign σ of the d-axis current i ｄ to be flowed for warm-up control to σ = +1. These are opposite to steps S16 to S17.

[0086] That is, when the load of the motor 15 at the start of travel is small and it is expected that the phase current i ｕｖｗ is relatively small even for a specific switching element, the current direction setting unit 54 sets the sign σ of the d-axis current i ｄ to be flowed for warm-up control so that the direction of the d-axis current i ｄ is the same as the direction of the d-axis current i ｄ flowing at the start of travel. Therefore, even in the warm-up control, the phase current flows through the maximum current element as in the case of starting. s

[0087] Thus, when the amount of the d-axis current i ｄ to be flowed for warm-up control and its sign σ are set, the warm-up control is started in step S22. That is, the current command setting unit 55 sets the dq-axis current command i ｄ | and the selection unit 43 outputs this dq-axis current command i ｄｑ２ ＊ for warm-up control as the final dq-axis current command i ｗａｒｍ according to the warm-up command C ｄｑ２ ＊ <A ｄｑ [[ID=3l]] ＊ . Thereby, the d-axis current i ｄ is applied to the motor 15 that has stopped rotating, and the transport of the heat generated in the inverter 14 and the motor 15 to the battery 10 is started.

[0088] In this embodiment, for the sake of explanation, an example is described in which the warm-up current command calculation unit 42 has a functional block (start-time current identification unit 53) that identifies the maximum current element, but it is not limited to this. For example, the dq axis current i at start-up ｄｑ If the current is predetermined using a table or the like, the starting current specification unit 53 can be omitted.

[0089] As described above, in this embodiment, the electric vehicle 100 receives the dq axis current command i at the time of starting. ｄｑ ＊ The d-axis current command i is predetermined by the dq-axis current command map. Therefore, the current direction setting unit 54 sets the d-axis current command i at startup as determined by the dq-axis current command map. ｄ ＊ Based on the sign, more directly, the d-axis current i for warm-up control ｄ The sign σ can be set.

[0090] In this way, by having the current direction setting unit 54 refer to the dq axis current map, even when the starting current specification unit 53 is omitted, the current direction setting unit 54 will have the d axis current i for warm-up control set. ｄ The criteria for setting the sign σ are the same as above. That is, in principle, if it is determined that the load on the motor 15 is large at the time of starting, the current direction setting unit 54 sets the d-axis current command i at the time of starting. ｄ ＊ The d-axis current i for warm-up control is set to be in the opposite direction (opposite sign). ｄ The sign σ is set. Then, in exceptional cases, such as when it is determined that the load on the electric motor 15 is small at the time of starting, the current direction setting unit 54 sets the d-axis current command i at the time of starting. ｄ ＊ The d-axis current i for warm-up control is set to have the same direction (same sign) as the other. ｄ Set the sign σ.

[0091] Therefore, if the starting current specification unit 53 is omitted by having the current direction setting unit 54 refer to the dq axis current map, steps S14 to S21 are changed as follows. First, the current direction setting unit 54 refers to the dq axis current map and determines the starting d axis current i ｄ (d-axis current command i ｄ ＊The sign σ′ of ) is determined. Then, in step S13, the gradient ψ is the gradient threshold ψ ｔｈ If it is greater than σ, the current direction setting unit 54 sets the d-axis current i for warm-up control according to σ = -1 × σ'. ｄ The sign σ is the d-axis current i at startup. ｄ The sign is set to the opposite sign of the other. On the other hand, in step S13, the gradient ψ is set to the gradient threshold ψ ｔｈ If the following conditions are met, the current direction setting unit 54 sets the d-axis current i for warm-up control according to σ = +1 × σ'. ｄ The sign σ is the d-axis current i at startup. ｄ Set to the same sign as the previous sign.

[0092] Figure 7 is a flowchart showing the process until warm-up is complete. As shown in Figure 7, when warm-up control is started, in step S31, the current direction setting unit 54 sets the battery temperature T that has risen due to warm-up control. ｂａｔ and the second temperature threshold T ｔｈ２ Compare the following. In step S31, the battery temperature T ｂａｔ However, the second temperature threshold T ｔｈ２ If it is lower than the battery temperature T, the current direction setting unit 54 will set ｂａｔ Monitoring will continue. Meanwhile, in step S31, the battery temperature T ｂａｔ The second temperature threshold T ｔｈ２ If the above is detected, the process proceeds to step S32, where the current direction setting unit 54 checks whether a phase current is flowing through the maximum current element based on the set value of sign σ.

[0093] If it is confirmed in step S32 that a phase current is already flowing through the maximum current element, the process proceeds to step S33, where the current direction setting unit 54 sets the d-axis current i for warm-up control. ｄ The setting of the sign σ is maintained. On the other hand, if it is confirmed in step S32 that no phase current is flowing through the maximum current element, the process proceeds to step S34, and the current direction setting unit 54 sets the d-axis current i for warm-up control. ｄ The sign σ of the setting is reversed. That is, the battery temperature T is controlled to some extent by the warm-up control. ｂａｔ When the current rises, the current direction setting unit 54 deliberately sets the d-axis current i for warm-up control so that the phase current flows to the maximum current element, just as during starting.ｄ Change the direction (sign σ).

[0094] Furthermore, in step S35, the current setting unit 51 sets the battery temperature T ｂａｔ Accordingly, the d-axis current i for warm-up control ｄ Current quantity | i ｄ | Reduce.

[0095] Subsequently, in step S36, the warm-up requirement determination unit 32 determines the battery temperature T ｂａｔ The first temperature threshold T ｔｈ１ The completion of warm-up control is determined by whether or not the battery temperature T is reached. ｂａｔ The first temperature threshold T ｔｈ１ If the above temperature is reached, the warm-up necessity determination unit 32 issues a warm-up command C indicating that warm-up control is unnecessary. ｗａｒｍ Set this. This terminates the warm-up control. Note that in step S36, the battery temperature T ｂａｔ However, the first temperature threshold T ｔｈ１ If the value is smaller than this, the control returns to step S31. This allows the warm-up control to continue.

[0096] Figure 8 shows the d-axis current i for warm-up control. ｄ and phase current i ｕｖｗ This graph shows the relationship. Figure 8(A) shows the negative d-axis current i depending on the rotor's stopping position (electrical angle θ). ｄ Phase current i when flowing ｕｖｗ This is shown in Figure 8(B), where the positive d-axis current i depends on the rotor's stopping position (electrical angle θ). ｄ Phase current i when flowing ｕｖｗ This indicates.

[0097] As shown in Figures 8(A) and 8(B), the d-axis current i is supplied to the non-rotating electric motor 15. ｄ When flowing, the positive or negative d-axis current i ｄ It can also flow. However, the positive d-axis current i ｄ and negative d-axis current i ｄ When flowing, the phase current i ｕｖｗ The phases are reversed. For example, when θ = 0, the negative d-axis current i ｄ When flowing, the U-phase current i ｕ is a negative value, V-phase current i ｖand W-phase current i ｗ This becomes a positive value. In contrast, when θ = 0, the positive d-axis current i ｄ When flowing, the U-phase current i ｕ is a positive value, V-phase current i ｖ and W-phase current i ｗ This becomes a negative value. Therefore, the d-axis current i ｄ The phase current i in inverter 14 depends on the sign of i. ｕｖｗ The switching elements through which the signal passes are different. Specifically, they are as follows:

[0098] Figure 9 shows the negative d-axis current i when θ = 0. ｄ Phase current i in inverter 14 when flowing ｕｖｗ This is an explanatory diagram showing the flow. As shown in Figure 9, for example, when θ = 0, the negative d-axis current i ｄ When flowing, the phase current i ｕｖｗ The fluid flows from the battery 10 through VP (V-phase upper arm) and WP (W-phase upper arm) to the electric motor 15, and then returns to the battery 10 through UN (U-phase lower arm).

[0099] Figure 10 shows the positive d-axis current i when θ = 0. ｄ Phase current i in inverter 14 when flowing ｕｖｗ This is an explanatory diagram showing the flow. As shown in Figure 10, for example, when θ = 0, the positive d-axis current i ｄ When flowing, the phase current i ｕｖｗ The fluid flows from the battery 10 through the UP (U-phase upper arm) to the electric motor 15, and then returns to the battery 10 through the VN (V-phase lower arm) and WN (W-phase lower arm).

[0100] Figure 11 shows the phase current i when the electric vehicle 100 starts moving from the state θ = 0. ｕｖｗ This is an explanatory diagram showing the flow. In the electric motor 15 of this embodiment, when the electric vehicle 100 starts moving from the state θ = 0, the negative d-axis current i ｄ This will result in a current flowing. Here, as shown in Figure 11, the phase current i ｕｖｗThe current flows from the battery 10 through VP (V-phase upper arm) to the motor 15, and then returns to the battery 10 through UN (U-phase lower arm) and WN (W-phase lower arm). When θ = 0, the element with the maximum current is VP.

[0101] Figure 12 shows the negative d-axis current i in warm-up control when θ = 0. ｄ This graph schematically shows the phase current changes when the electric vehicle 100 starts moving after the current is applied. Figure 12(A) shows the accelerator operation amount A ｐｏ The changes are shown. Figure 12(B) shows the U-phase current i ｕ This is shown in Figure 12(B), where the current i flowing through UP (U-phase upper arm) is shown. ＵＰ The dashed line indicates the current i flowing through UN (U-phase lower arm). ＵＮ This is shown by a dashed line. Figure 12(C) shows the V-phase current i ｖ This is shown in Figure 12(C), where the current i flowing through VP (V-phase upper arm) is shown. ＶＰ The dashed line indicates the current i flowing through VN (V-phase lower arm). ＶＮ This is shown by a dashed line. And Figure 12(D) shows the W-phase current i ｗ This is shown in Figure 12(D), where the current i flowing through WP (W-phase upper arm) is shown. ＷＰ The dashed line indicates the current i flowing through WN (W phase lower arm). ＷＮ This is shown by a dashed line. Time t ０ This is the time when the accelerator was pressed and the electric vehicle 100 started moving. Here, time t ０ Previously, the negative d-axis current i ｄ (i ｄ <0) It is assumed that warm-up control is performed by flowing.

[0102] As shown in Figures 12(B) to (D), when θ = 0, the negative d-axis current i ｄ When performing warm-up control using this method, the phase current i is set to UN, VP, and WP. ｕｖｗ A current flows. Then, at the start, phase current i flows to UN, VP, and WN. ｕｖｗ A current flows through VP, which is the element with the maximum current at startup, from the time warm-up control is performed until the phase current (i ｖ ) flows. Therefore, when θ = 0, a negative d-axis current i ｄWhen warm-up control is performed using this method, the temperature of VP, which is the element with the maximum current at the time of starting, will have already risen by the time the electric vehicle 100 is about to start.

[0103] Therefore, when starting, a large torque T ｍ When a large output is required and a large load is placed on the motor 15, the phase current i is affected by the temperature limit (heat resistance limit) of VP, which is the maximum current element. ｕｖｗ This is limited, and the motor 15 is required to produce a torque T of a certain size. ｍ It may not be possible to output this.

[0104] For example, when starting an electric vehicle 100 on an uphill road, a large torque T ｍ If an output is required, a negative d-axis current i is generated before starting. ｄ When warm-up control is performed using this method, the phase current i is affected by the temperature limit of the maximum current element (VP) at startup. ｕｖｗ In some cases, this may be limited. In this case, the torque T of the electric motor 15 ｍ This is reduced. As a result, the motor 15 has the torque T required to climb the slope. ｍ This can result in the inability to generate the necessary power, preventing the electric vehicle 100 from starting.

[0105] Figure 13 shows the positive d-axis current i in warm-up control when θ = 0. ｄ This graph schematically shows the phase current changes when the electric vehicle 100 starts moving after the current is applied. Figure 13(A) shows the accelerator operation amount A ｐｏ The changes are shown. Figure 13(B) shows the U-phase current i ｕ This is shown in Figure 13(C) where the V-phase current i ｖ This is shown. And Figure 13(D) shows the W-phase current i ｗ This is shown. In Figures 13(B) to 13(D), the dashed and dotted lines represent the current passing through each switching element, similar to Figure 13. Also, time t ０ This is the time when the accelerator is pressed and the electric vehicle 100 starts moving, similar to Figure 12. However, here, time t ０ Previously, the positive d-axis current i ｄ (i ｄ It is assumed that warm-up control is performed by flowing > 0).

[0106] As shown in Figures 13(B) to (D), when θ = 0, the positive d-axis current i ｄ When performing warm-up control using UN, VP, and WP, ​​the phase current i ｕｖｗ A current flows. Then, at the start, phase current i flows to UN, VP, and WN. ｕｖｗ A current flows through it. In other words, the VP, which is the element with the highest current at startup, has a phase current (i) when warm-up control is being performed. ｖ ) does not flow. Therefore, when θ = 0, the positive d-axis current i ｄ When warm-up control is performed using this method, the temperature of VP, which is the element with the maximum current at the time of starting, will have not risen significantly when the electric vehicle 100 is about to start moving.

[0107] Therefore, when starting, a large torque T ｍ Even when a large load is placed on the motor 15 due to the required output, the phase current i is maintained by the temperature limit of VP, which is the maximum current element. ｕｖｗ This makes it easier to avoid limitations. In other words, the motor 15 can achieve the required torque T ｍ It is easy to output.

[0108] For example, when starting an electric vehicle 100 on an uphill road, a large torque T ｍ If an output is required, a positive d-axis current i is needed before starting. ｄ If warm-up control is performed using this method, the phase current i will be limited by the temperature of the maximum current element (VP) when starting. ｕｖｗ This is not limited. Therefore, the torque T of the motor 15 is limited by the temperature limit of the maximum current element (VP). ｍ The torque T required for climbing is not reduced. Therefore, the electric motor 15 is not reduced. ｍ This can generate the necessary power, allowing the electric vehicle 100 to start.

[0109] Therefore, in this embodiment, the current direction setting unit 54 identifies the maximum current element at the time of starting and sets the phase current i to that maximum current element. ｕｖｗ To prevent the flow, a d-axis current i is supplied for warm-up control. ｄ The direction (sign σ) is set. Therefore, even if warm-up control is performed before starting, the torque T of the motor 15 is limited by the temperature limit of the maximum current element. ｍThe torque T required for climbing is not reduced. Therefore, the electric motor 15 is not reduced. ｍ This can generate the necessary power, allowing the electric vehicle 100 to start.

[0110] Figure 14 is a schematic graph showing the torque response during acceleration. In Figure 14, the solid line graph G １ Therefore, the d-axis current i at the start ｄ In the opposite direction, the d-axis current i for warm-up control is used. ｄ Torque T when flowing ｍ This shows the responsiveness. That is, the solid line graph G １ The maximum current element has a phase current i ｕｖｗ To prevent the flow, the d-axis current i for warm-up control is used. ｄ This shows the torque response when the sign σ is set. Also, in Figure 14, the dashed line graph G ２ Therefore, the d-axis current i at the start ｄ In the same direction, d-axis current i for warm-up control ｄ Torque T when flowing ｍ This shows the responsiveness. That is, the dashed graph G ２ The maximum current element has a phase current i ｕｖｗ The d-axis current i for warm-up control flows so that it flows. ｄ The torque response is shown when the sign σ is set. And graph G is shown by the dashed line. ３ This is graph G １ and graph G ２ The difference is shown at time t. １ Torque T ｍ The target value (torque command T ＊ This is the time when the value of ) is reached.

[0111] As shown in Figure 14, in warm-up control, the d-axis current i is in the opposite direction to that during starting. ｄ When this is applied, the d-axis current i is in the opposite direction to when starting. ｄ Compared to when flowing, Torque T ｍ The response is delayed. That is, in warm-up control, the phase current i is applied to the maximum current element. ｕｖｗ To prevent the flow of the warm-up control d-axis current i ｄ When the sign σ is set, the torque T is slightly different. ｍ The response will be delayed.

[0112] Therefore, in this embodiment, the current direction setting unit 54, in principle, sets the d-axis current i such that no phase current flows to the maximum current element. ｄ While setting the sign σ, the load on the electric motor 15 at the time of starting and the battery temperature T ｂａｔ Accordingly, the d-axis current i ｄ We are adjusting the setting of the sign σ.

[0113] Specifically, in this embodiment, when the road surface gradient ψ is small and it is expected that the temperature limit of the maximum current element will not be a substantial problem, the current direction setting unit 54 sets the torque T ｍ Prioritizing responsiveness, the phase current i is deliberately set to the maximum current element. ｕｖｗ The d-axis current i during warm-up control flows so that it flows. ｄ The sign σ corresponds to the d-axis current i at startup. ｄ It is set in the same direction (steps S18 to S21).

[0114] Furthermore, in this embodiment, the battery temperature T is controlled by warm-up control. ｂａｔ When the torque T rises to a certain extent, the current direction setting unit 54 sets the torque T ｍ Prioritizing responsiveness, the phase current i is deliberately set to the maximum current element. ｕｖｗ The d-axis current i during warm-up control flows so that it flows. ｄ The sign σ corresponds to the d-axis current i at startup. ｄ It is set in the same direction (step S34).

[0115] Therefore, in this embodiment, the temperature rise of the maximum current element in warm-up control is avoided while torque T ｍ Responsiveness is ensured.

[0116] [First Modification] In the above embodiment, when the electric vehicle 100 starts, the d-axis current i is controlled in the opposite direction to that at the time of starting, depending on the degree of load on the electric motor 15 during warm-up control. ｄ Either flow (steps S14 to S17), or d-axis current i in the same direction as when starting ｄ The system switches between flowing (steps S18-S21) but is not limited to this. For example, even if warm-up control is required, the d-axis current i for warm-up control is not the primary method. ｄ Current quantity | i ｄWhen | is small, the temperature limit of the maximum current element during startup is unlikely to be a problem. Therefore, depending on the amount of d-axis current i ｄ flowing for warm-up control, |i ｄ |, during warm-up control, it may be switched whether to flow the d-axis current i ｄ in the opposite direction to that during startup (Steps S14 to S17), or to flow the d-axis current i ｄ in the same direction as that during startup (Steps S18 to S21).

[0117] FIG. 15 is a flowchart relating to the warm-up control of the first modification. As shown in FIG. 15, in this first modification, Step S40 is provided between Step S12 and Step S13. And in Step S40, the current direction setting unit 54 compares the magnitude of the d-axis current i ｄ flowing for warm-up control (that is, the amount of current |i ｄ |) with the current threshold value i ｄ－ｔｈ . The current threshold value i ｄ－ｔｈ is preset based on experiments or simulations, etc.

[0118] In Step S40, when the amount of current |i ｄ | is greater than the current threshold value i ｄ－ｔｈ and there is a possibility that the temperature limit of the maximum current element becomes a problem during the startup of the electric vehicle 100, it proceeds to Step S13. The processing after Step S13 is the same as that in the above embodiment.

[0119] On the other hand, in Step S40, when the amount of current |i ｄ | is less than or equal to the current threshold value i ｄ－ｔｈ and there is a low possibility that the temperature limit of the maximum current element becomes a problem during the startup of the electric vehicle 100, it proceeds to Step S18. The processing after Step S18 is the same as that in the above embodiment. That is, when the amount of the d-axis current i ｄ flowing for warm-up control, |i ｄ |, is small, the electric vehicle 100 can perform warm-up control by flowing the d-axis current i ｄ in the same direction as that during startup regardless of the load of the motor 15 during startup.

[0120] Thus, depending on the amount of the d-axis current i ｄ flowing for warm-up control, |i ｄWhen | is small, the d-axis current i is in the same direction as when starting. ｄ By flowing it, torque T ｍ Responsiveness is ensured.

[0121] [Second Modification] In the above embodiment, as an example, when estimating the load on the electric motor 15 when the electric vehicle 100 starts moving based on the gradient ψ of the road surface, only the gradient ψ is referred to, but this is not limited to this. For example, when the driver is riding in the electric vehicle 100 and the vehicle is stopped by the friction brakes, and warm-up control is performed, the load on the electric motor 15 at the time of starting can be estimated more accurately. For example, the starting load estimation unit 52 may estimate the load on the electric motor 15 at the time of starting as follows.

[0122] Figure 16 is a flowchart relating to warm-up control of a second modified example. As shown in Figure 16, step S13 in the above embodiment is extended to steps S41 to S44.

[0123] In step S41, the starting load estimation unit 52 determines the magnitude of the road surface gradient ψ |ψ| as the gradient threshold ψ. ｔｈ Compare with the following. In step S41, the magnitude of the road surface gradient ψ |ψ| is the gradient threshold ψ ｔｈ If the road surface gradient ψ is small and it is expected that the load on the electric motor 15 at startup will be small, the process proceeds to step S18. The processing from step S18 onward is the same as in the above embodiment.

[0124] On the other hand, in step S41, the magnitude of the road surface gradient ψ |ψ| is the gradient threshold ψ ｔｈ If it is greater than this, the process proceeds to step S42. In step S42, the starting load estimation unit 52 checks whether the gradient ψ is positive or negative. That is, the starting load estimation unit 52 checks whether the road surface is uphill or downhill for the electric vehicle 100.

[0125] In step S42, if the gradient ψ is positive and the electric vehicle 100 is stopped facing the uphill direction, the process proceeds to step S43, where the starting load estimation unit 52 checks whether the shift lever is set to the D range (drive range).

[0126] Then, in step S43, if the shift lever is set to the D range and it is determined that the electric vehicle 100 is about to start moving uphill, the starting load estimation unit 52 determines that the load on the electric motor 15 at the time of starting is large and proceeds to step S14. The processing from step S14 onwards is the same as in the above embodiment. Also, in step S43, if the shift lever is set to a range other than D (for example, the R range) and it is determined that the electric vehicle 100 is about to start moving downhill, the starting load estimation unit 52 determines that the load on the electric motor 15 at the time of starting is small and proceeds to step S18. The processing from step S18 onwards is the same as in the above embodiment.

[0127] Furthermore, in step S42, if the gradient ψ is negative and the electric vehicle 100 is stopped facing downhill, the process proceeds to step S44, where the starting load estimation unit 52 checks whether the shift lever is set to the R range (rearrange).

[0128] Then, in step S44, if the shift lever is set to the R range and it is determined that the electric vehicle 100 is about to start moving uphill, the starting load estimation unit 52 determines that the load on the electric motor 15 at the time of starting is large and proceeds to step S14. The processing from step S14 onwards is the same as in the above embodiment. Also, in step 44, if the shift lever is set to a range other than R (for example, D range) and it is determined that the electric vehicle 100 is about to start moving downhill, the starting load estimation unit 52 determines that the load on the electric motor 15 at the time of starting is small and proceeds to step S18. The processing from step S18 onwards is the same as in the above embodiment.

[0129] Thus, by considering the road surface gradient ψ and the orientation of the electric vehicle 100, the load on the electric motor 15 at startup can be estimated, and in particular, the d-axis current i supplied for warm-up control can be appropriately determined. ｄ The orientation can be set.

[0130] Furthermore, the first and second modified examples described above can be implemented in combination.

[0131] As described above, the control method for an electric vehicle according to the above embodiment and each of its modifications is as follows: In an electric vehicle 100 having a battery 10 and an electric powertrain 11 including an inverter 14 and an electric motor 15, when the electric vehicle 100 is stopped, the electric motor 15 is supplied with a d-axis current i ｄ This is a control method for an electric vehicle that uses the heat generated by the electric powertrain 11, which flows through it, to warm up the battery 10. In this control method, when warming up the battery 10, the d-axis current i when the electric vehicle 100 starts moving ｄ The d-axis current i has the opposite sign to the one shown. ｄ Set it.

[0132] Thus, when the electric vehicle 100 is stationary and the battery 10 is warmed up using the heat from the electric powertrain 11, the d-axis current i at the time of starting ｄ The d-axis current i has the opposite sign (the sign is reversed). ｄ By setting this, the torque T due to the heat resistance limit of the maximum current element at startup ｍ This makes it less likely for output limitations to occur. Therefore, even if warm-up control is performed before starting, the motor 15 will still need torque T ｍ This prevents the electric vehicle 100 from being unable to start due to the inability to generate the necessary energy.

[0133] In the electric vehicle control methods according to the above embodiments and their respective modifications, for example, when the electric vehicle 100 starts moving, the inverter 14 identifies the maximum current element (e.g., VP), which is a switching element through which the maximum phase current flows, and when the battery 10 is warmed up, the maximum current element receives a phase current i ｕｖｗ No current flows, and the switching element (e.g., VN) paired with the maximum current element receives a phase current i ｕｖｗ The d-axis current i flows ｄ Set it.

[0134] Thus, when the electric vehicle 100 is stationary and the battery 10 is warmed up using the heat from the electric powertrain 11, the phase current i is applied to the maximum current element. ｕｖｗ No current flows, and the corresponding switching element receives a phase current i ｕｖｗ The d-axis current i flows ｄBy setting this, the torque T due to the heat resistance limit of the maximum current element at startup ｍ This makes it less likely for output limitations to occur. Therefore, even if warm-up control is performed before starting, the motor 15 will still need torque T ｍ This prevents the electric vehicle 100 from being unable to start due to the inability to generate the necessary energy.

[0135] In the electric vehicle control method according to the above embodiment and each of its modifications, when the electric vehicle 100 starts moving, the load on the electric motor 15 is estimated, and if the load is above a predetermined load threshold, when warming up the battery 10, a phase current i is supplied to the switching element (e.g., VN) paired with the maximum current element (e.g., VP). ｕｖｗ The d-axis current i flows ｄ This is set. On the other hand, when the load is smaller than the load threshold, when warming up the battery 10, the maximum current element (VP) receives a phase current i ｕｖｗ The d-axis current i flows ｄ Set it.

[0136] In this way, the d-axis current i is adjusted according to the load applied to the electric motor 15 at the time of starting. ｄ By changing the setting (sign σ), depending on the situation, the temperature limit of the maximum current element at startup can be avoided, and when the temperature limit of the maximum current element is not a problem, the torque T ｍ This ensures responsiveness.

[0137] In the above embodiment and the control method for electric vehicles according to each of its modifications, the gradient ψ of the road surface on which the electric vehicle 100 is stopped is obtained, and the load is estimated based on the gradient ψ.

[0138] The scene of starting on a steep road surface is a large torque T ｍ This is one of the typical scenarios where a high output is required, placing a large load on the motor 15. Therefore, as described above, if the load on the motor 15 at startup is estimated by the road surface gradient ψ, then we can identify scenarios where the temperature limit of the maximum current element at startup should be avoided, and scenarios where the temperature limit of the maximum current element is not a problem, and torque T ｍ It allows for the appropriate identification of scenarios where responsiveness must be ensured.

[0139] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ), the phase current i is supplied to the maximum current element (e.g., VP). ｕｖｗ The d-axis current i flows ｄ Switch the settings.

[0140] In this way, the battery temperature T is controlled by warm-up control. ｂａｔ When it rises to a certain extent, the phase current i reaches the maximum current element. ｕｖｗ The d-axis current i flows as if ｄ Switching this setting avoids the temperature limit of the maximum current element while maintaining torque T at startup. ｍ This can improve responsiveness.

[0141] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ) the d-axis current i ｄ Magnitude (current | i ｄ |) Reduce

[0142] In this way, the battery temperature T is controlled by warm-up control. ｂａｔ When it rises to a certain level, the d-axis current i for warm-up control is activated. ｄ Current quantity | i ｄ Reducing | avoids the temperature limit of the maximum current element while maintaining torque T at startup. ｍ This can improve the responsiveness of the system.

[0143] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ), the phase current i is supplied to the maximum current element (e.g., VP). ｕｖｗ The d-axis current i flows ｄ Switch and the d-axis current i ｄ Magnitude (current | i ｄ |) Reduce

[0144] In this way, the battery temperature T is controlled by warm-up control. ｂａｔWhen it rises to a certain extent, the phase current i reaches the maximum current element. ｕｖｗ The d-axis current i flows as if ｄ While switching the settings, the d-axis current i for warm-up control ｄ Current quantity | i ｄ Reducing | avoids the temperature limit of the maximum current element and the torque T at startup. ｍ It is particularly easy to achieve both responsiveness and performance.

[0145] In the above embodiment and each of its modifications (especially the first modification), the control method for an electric vehicle is controlled by the temperature of the battery 10 (T ｂａｔ ) based on the d-axis current i ｄ Magnitude (current | i ｄ Determine the d-axis current i ｄ Size (|i ｄ |) is a predetermined current threshold (i ｄ－ｔｈ If the value is greater than or equal to the maximum current element (e.g., VP), when warming up the battery 10, the switching element (e.g., VN) paired with the maximum current element (e.g., VP) receives a phase current i ｕｖｗ The d-axis current i flows ｄ Set the d-axis current i. ｄ Size (|i ｄ |) is the current threshold (i ｄ－ｔｈ If it is smaller than ), when warming up the battery 10, the phase current i will be supplied to the maximum current element (e.g., VP). ｕｖｗ The d-axis current i flows ｄ Set it.

[0146] Thus, the d-axis current i is supplied for warm-up control. ｄ Current quantity | i ｄ When | is small, problems due to the temperature limit of the maximum current element are less likely to occur, so the torque T at startup ｍ This allows for prioritizing responsiveness. This avoids the temperature limit of the maximum current element and the torque T at startup. ｍ This makes it particularly easier to achieve both responsiveness and performance.

[0147] The control device for the electric vehicle according to the above embodiment and each of its modifications is for an electric vehicle 100 having a battery 10 and an electric powertrain 11 including an inverter 14 and an electric motor 15, and when the electric vehicle 100 is stopped, a d-axis current i is supplied to the electric motor 15.ｄ This is a control device (controller 13) for an electric vehicle that warms up the battery 10 using the heat generated by the electric powertrain 11 when the electric vehicle 100 starts moving. When the battery 10 is warmed up, this control device (controller 13) uses the d-axis current i ｄ The d-axis current i has the opposite sign to the one shown. ｄ It includes a current direction setting unit 54 for setting the current direction.

[0148] Thus, when the electric vehicle 100 is stationary and the battery 10 is warmed up using the heat from the electric powertrain 11, the phase current i is applied to the maximum current element. ｕｖｗ No current flows, and the corresponding switching element receives a phase current i ｕｖｗ The d-axis current i flows ｄ By setting this, the torque T due to the heat resistance limit of the maximum current element at startup ｍ This makes it less likely for output limitations to occur. Therefore, even if warm-up control is performed before starting, the motor 15 will still need torque T ｍ This prevents the electric vehicle 100 from being unable to start due to the inability to generate the necessary energy.

[0149] [Note] The above embodiments and their respective modifications include the following electric vehicle control methods and control devices.

[0150] The control method for an electric vehicle according to the above embodiment and each of its modifications is as follows: In an electric vehicle 100 having a battery 10 and an electric powertrain 11 including an inverter 14 and an electric motor 15, when the electric vehicle 100 is stopped, a d-axis current i is supplied to the electric motor 15. ｄ This is a control method for an electric vehicle that uses the heat generated by the electric powertrain 11, which flows through it, to warm up the battery 10. This control method uses the d-axis current i that flows when the electric vehicle 100 starts moving. ｄ The direction (sign σ) of the current is determined, and the d-axis current i flows when the battery 10 is warmed up and the electric vehicle 100 starts moving. ｄ The d-axis current i is in the opposite direction to the direction (σ). ｄ Let it flow.

[0151] In the electric vehicle control method according to the above embodiment and each of its modifications, the load on the electric motor 15 is estimated when the electric vehicle 100 starts moving, and if the load is above a predetermined load threshold, the d-axis current i that flows when the electric vehicle 100 starts is warmed up. ｄ The d-axis current i is in the opposite direction to the direction of ｄ When the load is less than a predetermined load threshold, the d-axis current i flows when the electric vehicle 100 starts moving, while the battery 10 is warming up. ｄ d-axis current i in the same direction ｄ Let it flow.

[0152] In the above embodiment and the control method for electric vehicles according to each of its modifications, the gradient ψ of the road surface on which the electric vehicle 100 is stopped is obtained, and the load is estimated based on the gradient ψ.

[0153] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ) the d-axis current i ｄ The direction (sign σ) of the d-axis current i that flows when the electric vehicle 100 starts is defined by the direction (sign σ) of the current i. ｄ Switch to the same direction (sign σ).

[0154] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ) the d-axis current i ｄ Size (|i ｄ |) Reduce

[0155] In the above embodiment and the control method for electric vehicles according to each of its modifications, the temperature of the battery 10 (T ｂａｔ ) is a predetermined temperature threshold (T ｔｈ２ When it exceeds ) the d-axis current i ｄ The direction (sign σ) of the d-axis current i that flows when the electric vehicle 100 starts is defined by the direction (sign σ) of the current i. ｄ Switch to the same direction (sign σ), and the d-axis current i ｄ Size (|i ｄ |) Reduce

[0156] In the above embodiment and each of its modifications (especially the first modification), the control method for an electric vehicle is controlled by the temperature of the battery 10 (T ｂａｔ ) based on the d-axis current i ｄ Size (|i ｄ Determine the d-axis current i ｄ Size (|i ｄ |) is a predetermined current threshold (i ｄ－ｔｈ ) If the value is greater than or equal to the value, the d-axis current i that flows when the battery 10 is warmed up and when the electric vehicle 100 starts moving ｄ In the opposite direction, the d-axis current i ｄ Then, the d-axis current i ｄ Size (|i ｄ |) is the current threshold (i ｄ－ｔｈ If it is smaller than ), when warming up the battery 10, the d-axis current i that flows when the electric vehicle 100 starts moving ｄ d-axis current i in the same direction ｄ Let it flow.

[0157] The control device for the electric vehicle according to the above embodiment and each of its modifications is for an electric vehicle 100 having a battery 10 and an electric powertrain 11 including an inverter 14 and an electric motor 15, and when the electric vehicle 100 is stopped, a d-axis current i is supplied to the electric motor 15. ｄ This is a control device (controller 13) for an electric vehicle that warms up the battery 10 using the heat generated by the electric powertrain 11 when the electric vehicle 100 starts moving. ｄ A starting current identification unit 53 identifies the direction (sign σ) of the current, and when the battery 10 is warmed up, the d-axis current i flows when the electric vehicle 100 starts moving. ｄ The d-axis current i is in the opposite direction to the direction of ｄ It includes a current direction setting unit 54 for flowing current.

[0158] Although embodiments and modifications of the present invention have been described above, the configurations described in the above embodiments and modifications represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A control method for an electric vehicle having a battery and an electric powertrain including an inverter and an electric motor, wherein when the electric vehicle is stopped, the electric vehicle is warmed up using the heat of the electric powertrain generated by flowing a d-axis current through the electric motor, wherein when warming up the battery, the d-axis current is set to have the opposite sign to the d-axis current when the electric vehicle starts moving.

2. A method for controlling an electric vehicle according to claim 1, comprising: identifying a maximum current element, which is a switching element through which the maximum phase current flows, in the inverter when the electric vehicle starts moving; and setting the d-axis current such that no phase current flows through the maximum current element and a phase current flows through the switching element paired with the maximum current element when the battery is warmed up.

3. A method for controlling an electric vehicle according to claim 2, comprising: estimating the load on the electric motor when the electric vehicle starts moving; setting the d-axis current so that a phase current flows through the switching element paired with the maximum current element when warming up the battery if the load is greater than or equal to a predetermined load threshold; and setting the d-axis current so that a phase current flows through the maximum current element when warming up the battery if the load is less than the load threshold.

4. A method for controlling an electric vehicle according to claim 3, comprising: obtaining the gradient of the road surface on which the electric vehicle is stopped, and estimating the load based on the gradient.

5. A control method for an electric vehicle according to claim 2, comprising switching the setting of the d-axis current so that a phase current flows through the maximum current element when the temperature of the battery exceeds a predetermined temperature threshold.

6. A method for controlling an electric vehicle according to claim 1 or 2, wherein the magnitude of the d-axis current is reduced when the temperature of the battery exceeds a predetermined temperature threshold.

7. A method for controlling an electric vehicle according to claim 2, comprising switching the d-axis current and reducing the magnitude of the d-axis current so that a phase current flows through the maximum current element when the temperature of the battery exceeds a predetermined temperature threshold.

8. A method for controlling an electric vehicle according to claim 2, comprising: determining the magnitude of the d-axis current based on the temperature of the battery; setting the d-axis current so that a phase current flows through the switching element paired with the maximum current element when warming up the battery if the magnitude of the d-axis current is greater than or equal to a predetermined current threshold; and setting the d-axis current so that a phase current flows through the maximum current element when warming up the battery if the magnitude of the d-axis current is less than the current threshold.

9. A control device for an electric vehicle having a battery and an electric powertrain including an inverter and an electric motor, wherein when the electric vehicle is stopped, the control device warms up the battery using the heat of the electric powertrain generated by flowing a d-axis current through the electric motor, the control device for an electric vehicle comprising a current direction setting unit that sets the d-axis current having the opposite sign to the d-axis current when the electric vehicle starts moving when warming up the battery.

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