Electric-vehicle charging control method and electric-vehicle charging control device

Abstract

An electric-vehicle charging control method which charges a battery by boosting the power supplied from an external power supply by using an inverter and a rotary electric machine of an electric drive system equipped with a battery, a rotary electric machine, the rotor of which is provided with a three-phase coil and a permanent magnet, and an inverter interposed between the battery and the rotary electric machine, said method being configured in a manner such that: when it is necessary to warm up the battery, the controller charges in one of the following warm-up modes: a first mode in which the current value of the current flowing through a coil of a single phase of the three-phase coil is set to a first current value which is greater than zero and is the smallest value within a controllable range, and the current value of the current flowing through coils of the other two phases thereof is set to a second current value which is greater than the first current value; and a second mode in which the current value of the current flowing through the coils of two phases of the three-phase coil is set to a first current value, and the current value of the current flowing through a coil of the other one phase thereof is set to a second current value.

Description

Charging control method for electric vehicle and charging control device for electric vehicle

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

[0002] In recent years, drive systems for electric vehicles, such as batteries and electric motors, have been increasingly driven by higher voltages (e.g., 800 V). However, when an electric vehicle that is charged by power supplied from an external power source, such as a battery electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV), is charged by an external power source that is not compatible with high voltages, it is desirable to charge the vehicle by boosting the voltage.

[0003] US11230200B2 discloses a control method for charging a three-phase AC electric motor by receiving current from an external power source at the neutral point and boosting the voltage by switching an inverter. Specifically, the current value of one of the three phase coils is set to zero, and the current values ​​of the remaining two phase coils are set so that the torque of the electric motor becomes zero.

[0004] However, since the input current limit value of a battery is smaller as the battery temperature is lower, when charging at low temperatures, the input current value is limited, which may reduce the effect of boosting the voltage. For this reason, it is desirable to complete the warm-up of the battery as quickly as possible. A known method for quickly completing the warm-up of a battery is so-called d-axis current control, in which the component of current that contributes to torque (q-axis component) is set to zero and the component of current that does not contribute to torque (d-axis component) is passed through the electric motor, thereby warming up the electric motor by utilizing the heat generated by the current loss.

[0005] However, during charging using the control method described in the above document, the d-axis current control cannot be performed because the electric motor and inverter are used for voltage boosting. Furthermore, the above document does not mention shortening the time until warm-up is complete.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to achieve both promotion of battery warm-up and charging efficiency.

[0007] According to one aspect of the present invention, there is provided a charging control method for an electric vehicle, in which an electric drive system including a battery, a rotating electric machine whose rotor includes three-phase coils and permanent magnets, and an inverter interposed between the battery and the rotating electric machine uses the rotating electric machine and inverter to boost power supplied from an external power source and charge the battery. In this method, when warming up of the battery is required, a controller performs charging in either a first warm-up mode in which a current value flowing through one of the three-phase coils is set to a first current value that is greater than zero and is the smallest current value in a controllable range, and current values ​​flowing through the other two phase coils are set to a second current value that is greater than the first current value, or a second warm-up mode in which a current value flowing through two of the three-phase coils is set to the first current value, and current value flowing through the other phase coil is set to the second current value.

[0008] FIG. 1 is a block diagram showing a schematic configuration of a rotating electric machine system. FIG. 2 is a schematic circuit diagram of the rotating electric machine system. FIG. 3 is an equivalent circuit for the U-phase when a boost converter is configured. FIG. 4 is a block diagram showing the configuration of a controller when a DC / DC converter is configured using an inverter and a rotating electric machine. FIG. 5 is an explanatory diagram showing coil magnetic flux generated in a rotating electric machine during charging control. FIG. 6 is a time chart of current values ​​when a high-efficiency mode is performed. FIG. 7 is a time chart of current values ​​when a warm-up mode is performed. FIG. 8 is a circuit diagram showing an example of a circuit of a temperature adjustment system. FIG. 9 is a diagram showing the warm-up promotion effect of the warm-up mode. FIG. 10 is a flowchart showing a control routine for switching control between the warm-up mode and the high-efficiency mode. FIG. 11 is a time chart of current values ​​when the warm-up mode is performed in a modified example.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] Fig. 1 is a block diagram showing a schematic configuration of a rotating electric machine system 100. The rotating electric machine system 100 is, for example, a vehicle drive system or a power generation system mounted on an electrically powered vehicle such as a hybrid vehicle or an electric vehicle. Therefore, as shown in Fig. 1, the rotating electric machine system 100 includes a battery 10, an inverter 11, a rotating electric machine 12, and a controller 13. Of these, the inverter 11 and the rotating electric machine 12 are, for example, formed substantially integrally to form a so-called electric powertrain 14. An external charger 15 may also be connected to the rotating electric machine system 100.

[0011] The battery 10 is a rechargeable DC power supply. The battery 10 supplies power to drive the rotating electric machine 12. That is, when driving the rotating electric machine 12, the battery 10 supplies a DC voltage V ｄｃ On the other hand, when the rotating electrical machine 12 generates electric power, the battery 10 is charged with that electric power.

[0012] When the external charger 15 is connected, the battery 10 is charged by the power supplied by the external charger 15 via the electric powertrain 14. At this time, the input voltage V ＩＮ is boosted by the electric powertrain 14 as needed. This results in an output voltage V suitable for charging. ＯＵＴ In this embodiment, the battery 10 is charged by the voltage (DC voltage V ｄｃ ) is, for example, 800 V. The external charger 15 is a DC power supply, and its voltage (input voltage V ＩＮ ) is, for example, 400 V or 800 V. Therefore, when a 400 V external charger 15 is connected, the output voltage V ＯＵＴ is boosted to 800V.

[0013] The inverter 11 converts DC power output by the battery 10 into AC power and supplies it to the rotating electric machine 12. This drives the rotating electric machine 12. On the other hand, when the rotating electric machine 12 generates electric power, the inverter 11 converts the AC power generated by the rotating electric machine 12 into DC power and supplies it to the battery 10.

[0014] When an external charger 15 is connected to the rotating electric machine system 100, the inverter 11 can configure a boost converter together with the rotating electric machine 12. Specifically, all or some of the switching elements and free wheel diodes that configure the inverter 11 are used as elements of the boost converter. When the external charger 15 is a quick charger or the like, the inverter 11 configures a boost converter together with the rotating electric machine 12, and the input voltage V ＩＮ The output voltage V ＯＵＴ is applied to the battery 10.

[0015] The rotating electric machine 12 is an electric motor or a generator. When the rotating electric machine 12 is an electric motor, the rotating electric machine system 100 is a drive system for an electric vehicle or the like that is equipped with the rotating electric machine 12. When the rotating electric machine 12 is a generator, the rotating electric machine system 100 is a power generation system for a hybrid vehicle or the like that is equipped with the rotating electric machine 12. In this embodiment, the rotating electric machine 12 is an electric motor for driving a vehicle.

[0016] The rotating electric machine 12 is an AC synchronous motor with embedded permanent magnets and has multiple phases. Therefore, the rotating electric machine 12 includes a rotor with embedded permanent magnets 36 (see FIG. 5 ) and a stator with multiple independent coils. The rotating electric machine 12 rotates due to the interaction between the magnetic flux generated by the permanent magnets (hereinafter referred to as permanent magnet magnetic flux) and the composite magnetic flux (hereinafter referred to as coil magnetic flux) generated by the multiple-phase coils. The multiple-phase coils are connected in a so-called star connection (Y connection) and have a neutral point. In this embodiment, the rotating electric machine 12 is a three-phase AC synchronous motor with embedded permanent magnets. Therefore, the rotating electric machine 12 includes a rotor with permanent magnets 36 and a stator with three-phase (UVW) stator coils connected in a Y connection.

[0017] When the external charger 15 is connected to the rotating electric machine system 100, the rotating electric machine 12 and the inverter form a boost converter. Specifically, the coils of each phase are used as inductors of the boost converter. In this case, one terminal of the external charger 15 is connected to the neutral point of the rotating electric machine 12.

[0018] The current flowing through the coils of each phase (UVW) (hereinafter referred to as the three-phase current I ＵＶＷ ), and neutral point voltage V ｎ , the rotation angle θ of the rotor (permanent magnet 36) ｒ can be detected at any timing. ＵＶＷ is detected by the current sensor 16. The neutral point voltage V ｎ is detected by the voltage sensor 17. The rotation angle θ ｒ is detected by the rotation sensor 18. The rotation angle θ ｒ is measured counterclockwise in the UVW coordinate system, with the position of the U-phase coil (U) as the reference angle (0°).

[0019] The controller 13 is a control device that comprehensively controls the operation of each part of the rotating electric machine system 100. The controller 13 is configured, for example, by one or more computers, and is programmed to cause each part to perform a predetermined operation. In this embodiment, the controller 13 is a charge / discharge control device that controls charging or discharging of the battery 10 by configuring a DC / DC converter using the inverter 11 and the rotating electric machine 12. A charge / discharge control program for operating the inverter 11 and the rotating electric machine 12 as a DC / DC converter may be provided in the form of being stored in a storage medium.

[0020] Specifically, the controller 13 controls the overall operation of the rotating electric machine system 100 by inputting a PWM (pulse width modulation) signal to the inverter 11. For example, the controller 13 generates a PWM signal (referred to as a rotation control PWM signal) for controlling the rotation of the rotating electric machine 12, and controls the rotation speed and torque of the rotating electric machine 12 by inputting this to the inverter 11. The controller 13 generates the rotation control PWM signal based on, for example, the amount of accelerator operation or the like.

[0021] In this embodiment, even when an external charger 15 is connected to the rotating electric machine system 100, the controller 13 inputs a PWM signal (hereinafter referred to as a converter PWM signal) to the inverter 11 to operate the electric powertrain 14 as a DC / DC converter. This causes the inverter 11 and the rotating electric machine 12 to function as a step-up converter or a step-down converter. The controller 13 controls the three-phase current I ＵＶＷ , neutral point voltage V ｎ , and the rotation angle θ ｒ A PWM signal for the converter is generated based on the

[0022] The external charger 15 is provided separately from the vehicle on which the rotating electrical machine system 100 is mounted, and is, for example, a rapid charger or other charger installed in a charging station.

[0023] Fig. 2 is a schematic circuit diagram of the rotating electric machine system 100. As shown in Fig. 2, the battery 10 includes a battery main body 21 and relay switches 22a and 22b. The inverter 11 includes a smoothing capacitor 23 and a bridge circuit 24. The rotating electric machine 12 includes a U-phase coil (U), a V-phase coil (V), and a W-phase coil (W) as multi-phase coils.

[0024] The bridge circuit 24 has legs L corresponding to the UVW phases. Ｕ , L Ｖ , L Ｗ Each leg L Ｕ , L Ｖ , L Ｗ Each of the inverters 11 consists of two arms, an upper arm and a lower arm, and the coils U, V, and W of each phase are connected between them. Each arm is formed by a switching element and a freewheeling diode. The controller 13 inputs a PWM signal to the inverter 11 to control the timing of turning on (conducting) and off (disconnecting) the switching element of each arm.

[0025] Furthermore, the rotating electric machine system 100 includes relay switches 25, 26, and 27, a capacitor 28, and an external input / output terminal 29. These are components for connecting the external charger 15 and the rotating electric machine system 100.

[0026] The relay switch 25 is provided between a first terminal of the external input / output terminal 90 and one end of the battery 10, and the relay switch 26 is provided between a second terminal of the external input / output terminal 90 and the other end of the battery 10. The relay switch 27 is provided on a line connecting the first terminal of the external input / output terminal 90 and the neutral point of the rotating electric machine 12. The capacitor 28 is provided between the relay switch 27 and the neutral point of the rotating electric machine 12 so as to connect the first and second terminals of the external input / output terminal 90 in parallel.

[0027] The relay switches 25, 26, and 27 are each turned on / off independently by the controller 13. When there is no need to step up or step down the voltage, the relay switches 25 and 26 are turned on (conductive), and the relay switch 27 is turned off (disconnected). As a result, the external charger 15 is connected directly to the battery 10 without going through the inverter 11 and the rotating electric machine 12. On the other hand, when there is a need to step up or step down the voltage, the relay switch 25 is turned off, and the relay switches 26 and 27 are turned on. As a result, the external charger 15 is connected to the battery 10 via the rotating electric machine 12 and the inverter 11.

[0028] Figure 3 shows an equivalent circuit for the U phase when a boost converter is configured. As shown in Figure 3, when a boost converter is configured with the inverter 11 and the rotating electric machine 12, the upper arm switching element is maintained in the off state, and the lower arm switching element is controlled to be on / off. The coil of the rotating electric machine 12 (here, the U-phase coil) functions as an inductor of the boost converter. While the boost converter configuration for the U phase is shown here, the V phase and W phase are configured in the same way. The boost converters for each of the U, V, and W phases are connected in parallel to the battery 10.

[0029] Therefore, any one of the boost converters for the U, V, and W phases can be selected and used. In this embodiment, when the inverter 11 and the rotating electrical machine 12 are used as boost converters, the boost converters for all phases are used.

[0030] Furthermore, because the boost converters for each phase are connected in parallel, the on / off timing of the switching elements can be determined substantially independently for each phase. However, when current flows through the coils of each phase, torque is typically generated in the rotating electric machine 12. Therefore, when the inverter 11 and the rotating electric machine 12 are used as a boost converter, it is necessary to suppress the torque generated by the rotating electric machine 12 to an extent that the rotating electric machine 12 does not substantially rotate. The extent to which the rotating electric machine 12 does not substantially rotate refers to, for example, an extent to which an electric parking brake (so-called park lock) is not broken. In other words, when a boost converter is configured using the inverter 11 and the rotating electric machine 12 and the battery 10 is charged, at least the rotating electric machine 12 is maintained in a non-rotating state.

[0031] In addition, I １ is the output current before smoothing, and I ２ represents the output current after smoothing. When a step-down converter is configured using the inverter 11 and the rotating electric machine 12, the on / off of the upper arm switching element is controlled, and the lower arm switching element is maintained in the off state, in contrast to the step-up converter.

[0032] 4 is a block diagram showing the configuration of the controller 13 when a DC / DC converter is configured using the inverter 11 and the rotating electric machine 12. As shown in FIG. 4, the controller 13 includes a voltage controller 31, a current command generator 32, a coordinate converter 33, a current controller 34, and a PWM signal generator 35.

[0033] The voltage controller 31 detects the neutral point voltage V ｎ and the neutral point voltage V ｎ (hereinafter referred to as the neutral point voltage command V ｎ ＊ ) and based on this, the neutral point current command I ｎ ＊ More specifically, the voltage controller 31 calculates the neutral point voltage V by PI (Proportional-Integral) control, PID (Proportional-Integral-Differential) control, or the like. ｎ is the neutral point voltage command Vｎ ＊ The neutral point current command I ｎ ＊ Determine.

[0034] Neutral point current command I ｎ ＊ is the current flowing through the neutral point of the rotating electrical machine 12 (hereinafter referred to as the neutral point current I ｎ The neutral point voltage command V ｎ ＊ is set in advance by a higher-level controller (not shown) based on the specific characteristics of the external charger 15 connected to the rotating electrical machine system 100. ｎ ＊ In any case, in this embodiment, the neutral point voltage command V ｎ ＊ is predetermined.

[0035] The current command generator 32 generates a neutral point current command I ｎ ＊ and the detected rotation angle θ ｒ Based on this, the dq axis current command I ｄｑ ＊ Calculate the dq axis current command I ｄｑ ＊ is a command for a current component in the dq-axis coordinate system that rotates together with the rotor of the rotating electrical machine 12, i.e., the d-axis current I ｄ Command for (d-axis current command I ｄ ＊ ) and q-axis current I ｑ Command for (q-axis current command I ｑ ＊ ), is a general term for

[0036] The current command generator 32 generates the dq-axis current command I so that at least the rotating electric machine 12 does not generate any torque and maintains a non-rotating state. ｄｑ ＊ The current command generator 32 determines the neutral point current I ｎ is the neutral point current command I ｎ ＊ The dq axis current command I ｄｑ＊ Furthermore, the current command generator 32 determines the dq-axis current command I ｄｑ ＊ Determine.

[0037] In order to satisfy these conditions, the current command generator 32 essentially controls the d-axis current I ｄ does not flow, and the q-axis current I ｑ flows, and the three-phase current I ＵＶＷ The rotation angle θ is set so that the phase of at least one phase current differs from the phase of the other phase current. ｒ The dq-axis current command I ｄｑ ＊ That is, the dq-axis current command I calculated by the current command generator 32 is ｄｑ ＊ When current flows through the coils (boost converter) of each phase according to the above, the three-phase current I ＵＶＷ The phase (current phase) of at least one of the three phases is different from that of the other phases, and these three phase currents I ＵＶＷ The dq axis current I ｄｑ is converted into the q-axis current I ｑ The result is that only

[0038] The coordinate converter 33 converts the detected three-phase current I ＵＶＷ and the detected rotation angle θ ｒ Based on this, the d-axis current I ｄ and q-axis current I ｑ (Hereinafter, dq-axis current I ｄｑ (called "(x,y)") is calculated.

[0039] The current controller 34 outputs the dq axis current command I ｄｑ ＊ and the dq axis current I ｄｑ Based on this, the three-phase voltage command V ＵＶＷ ＊ More specifically, the current controller 34 calculates the actual d-axis current I by PI control, PID control, etc. ｄｑ is the dq axis current command I ｄｑ ＊ The three-phase voltage command V ＵＶＷ ＊ This three-phase voltage command VＵＶＷ ＊ is the neutral point current I ｎ While maintaining the three-phase current I ＵＶＷ Therefore, the three-phase voltage command V calculated by the current controller 34 is ＵＶＷ ＊ is essentially a command (current phase command) for the phase of the current flowing through each phase. ＵＶＷ ＊ is the U-phase voltage command V Ｕ ＊ , V-phase voltage command V Ｖ ＊ , and W-phase voltage command V Ｗ ＊ is a general term for

[0040] The PWM signal generator 35 generates a DC voltage V ｄｃ and three-phase voltage command V ＵＶＷ ＊ Based on this, a PWM signal is generated that determines the timing of switching each switching element of the inverter 11 according to a predetermined PWM method such as space vector PWM control. Here, the PWM signal generated by the PWM signal generator 35 is a PWM signal for the converter. The PWM signal generator 35 can generate PWM signals independently for the switching elements of each of the UVW phases. That is, the PWM signal generator 35 generates PWM signals for the leg L. Ｕ , L Ｖ , L Ｗ A different PWM signal can be generated for each of the pulses.

[0041] In this embodiment, the PWM signal generator 35 particularly generates a first PWM signal (hereinafter referred to as PWM １ ) and the second PWM signal (hereinafter referred to as PWM ２ Two types of PWM signals are generated: １ determines the timing for switching at least one of the switching elements for each of the UVW phases. ２ determines the timing for switching the switching elements of the other phases. １ and PWM ２The timing (phase) for switching the switching elements is different for the UVW phases. １ and a phase for switching the switching element according to the PWM ２ The current phase differs from the phase in which the switching element is switched according to the current.

[0042] This PWM １ and PWM ２ By switching the switching elements of each phase by the above, the rotating electric machine 12 does not generate torque substantially, and maintains a non-rotating state, while the neutral point current I ｎ is the neutral point current command I ｎ ＊ , and furthermore, the generation of eddy currents in the permanent magnet 36 is suppressed.

[0043] The following will describe in detail the operation of the charge / discharge control that controls the charging or discharging of the battery 10 using the DC / DC converter configured by the inverter 11 and the rotating electrical machine 12 as described above.

[0044] When the inverter 11 and the rotating electric machine 12 constitute a DC / DC converter, the controller 13 detects the rotation angle θ of the rotating electric machine 12 using the rotation sensor 18. ｒ After that, the controller 13 detects (acquires) the rotation angle θ ｒ Based on this, the controller 13 identifies a first direction, which is the direction of the permanent magnet magnetic flux, and a second direction perpendicular to the first direction. In a rotating coordinate system (dq-axis coordinate system) that rotates together with the rotor, the first direction is the d-axis direction, and the second direction is the q-axis direction. Then, as described above, the controller 13 generates the dq-axis current command I ｄｑ ＊ is determined, and the PWM signal generator 35 calculates the dq axis current command I ｄｑ ＊ PWM based on １ and PWM ２ Then, the controller 13 generates this PWM １ and PWM ２By controlling the operation of the switching elements of each phase in accordance with the above, the magnetic flux φ generated by the V-phase coil (V) and the W-phase coil (W) is Ｖ , φ Ｗ and the magnetic flux φ generated by the U-phase coil (U). Ｕ is generated along the second direction (q-axis direction). ＵＶＷ Adjust the phase of the signal.

[0045] 5 is an explanatory diagram showing the coil magnetic flux generated in the rotating electric machine 12 during charging control. When the inverter 11 and the rotating electric machine 12 are used as a DC / DC converter, the direction in which the permanent magnet 36 embedded in the rotor faces varies depending on the timing at which the rotation of the rotating electric machine 12 is stopped. For simplicity, however, it is assumed here that the N pole of the permanent magnet 36 faces the U-phase coil (U). In this case, the controller 13 controls the current (V-phase current I) flowing through the V-phase coil (V) and the W-phase coil (W). Ｖ and W-phase current I Ｗ ) phase by PWM １ and the current flowing through the V-phase coil (V) (V-phase current I Ｖ ) phase by PWM ２ The controller 13 controls the PWM １ and PWM ２ The phase difference between the V-phase and V-phase is set to 1 / 2 of the carrier wave period. As a result, as shown in FIG. 5, the coil magnetic flux (V-phase magnetic flux φ Ｖ and W-phase magnetic flux φ Ｗ The resultant magnetic flux of the U-phase coil (U-phase magnetic flux φ Ｕ ) and occur alternately.

[0046] When the magnetic flux Φ is generated as described above, the rotating electric machine 12 does not generate torque, and therefore the rotating electric machine 12 can maintain a state in which it has stopped rotating.

[0047] FIG. 6 is a time chart of the current value when the above-described control is performed. Ｖ and W-phase current I Ｗ are in phase and have the same current value. U-phase current I Ｕhas a smaller current value than these and has a phase difference of 1 / 2 period. In the following description, this current control is also referred to as a high efficiency mode.

[0048] However, the battery 10 has a limited amount of power that can be input and output (also referred to as input / output power) at low temperatures. Therefore, even if the high-efficiency mode is executed when the input / output power is limited, some of the boosted power may not be charged to the battery 10 and may be wasted, resulting in a decrease in charging efficiency. Therefore, it is desirable to quickly warm up the battery 10 to a temperature where the input / output power is not limited. A known method for warming up the battery 10 is d-axis current control, which controls the rotating electric machine 12 so that only the d-axis current flows, thereby generating heat and using that heat to warm up the battery 10. However, d-axis current control cannot be performed while the inverter 11 and the rotating electric machine 12 are being used as a boost converter. While it is possible to provide a heating device such as a PTC heater for warming up the battery 10, this increases the number of components, resulting in poor layout flexibility and increased costs.

[0049] Therefore, in this embodiment, the warm-up mode described below is executed to shorten the time required to warm up the battery 10 and improve charging efficiency.

[0050] 7 is a time chart of current values ​​in the warm-up mode. The solid lines in the figure represent the U-phase current, V-phase current, and W-phase current in the warm-up mode. The dashed lines in the figure represent the U-phase current, V-phase current, and W-phase current in the high-efficiency mode.

[0051] As shown in the figure, the V-phase current I Ｖ and W-phase current I Ｗ is the V-phase current I in high efficiency mode Ｖ and W-phase current I Ｗ And the U-phase current I Ｕ is the U-phase current I in high efficiency mode Ｕ This U-phase current I Ｕ is a current value that is greater than zero and is the smallest in the controllable range. This reduces the boost efficiency compared to the high efficiency mode.

[0052] While the inverter 11 and the rotating electric machine 12 are being used as a boost converter, current flows through them, generating heat due to the coil resistance and the current flow. The amount of heat generated is proportional to the square of the current, so the greater the current value, the greater the amount of heat generated. In warm-up mode, the input current from the external charger 15 is set to the same level as in the high-efficiency mode, thereby increasing the current value flowing through the V-phase coil and the W-phase coil and increasing the amount of heat generated. The heat generated by the rotating electric machine 12 is then transferred to the battery 10 via the temperature control system 101, which will be described later, to warm up the battery 10.

[0053] Note that, although the effect of promoting the warm-up of battery 10 can be obtained by setting the first current value to zero, setting the first current value to zero may cause an inrush current in the U-phase coil when switching to the high-efficiency mode upon completion of warm-up. For this reason, in this embodiment, in order to prevent an inrush current, the first current value is set to the smallest current value within the controllable range, rather than to zero.

[0054] 8 is a circuit diagram showing an example of a circuit of a temperature control system 101. This temperature control system 101 is applied to a vehicle having a front electric powertrain 14Fr for driving the front wheels and a rear electric powertrain 14Rr for driving the rear wheels. In this case, the rear electric powertrain 14Rr is used as a boost converter.

[0055] The temperature adjustment system 101 includes a first circuit 101A in which the battery 10 is disposed, a second circuit 101B in which the front electric powertrain 14Fr and the rear electric powertrain 14Rr are disposed, and a heat pump system 103 connecting the first circuit 101A and the second circuit 101B. The second circuit 101B also includes a bypass passage 44 that branches off from the second passage 40, passes through a second heat exchanger (radiator) 41, and rejoins the second circuit 101B.

[0056] The first circuit 101A includes a first refrigerant pump 52 that circulates the refrigerant within the circuit, the battery 10, and a first heat exchanger 53 into which the refrigerant that has received heat from the battery 10 flows. In the first heat exchanger 53, heat is exchanged between the refrigerant in the first circuit 101A and the refrigerant in the heat pump system 103.

[0057] The second circuit 101B includes a second refrigerant pump 43 that circulates refrigerant within the circuit, a third heat exchanger 45 that exchanges heat between the refrigerant and refrigerant that cools the front electric powertrain 14Fr, a fourth heat exchanger 46 that exchanges heat between the refrigerant and refrigerant that cools the rear electric powertrain 14Rr, and a fifth heat exchanger 57 into which refrigerant that has passed through the fourth heat exchanger 46 and the third heat exchanger 45 flows. A third pump 48 and a fourth pump 50 are respectively provided in the circuit 47 for the refrigerant that cools the front electric powertrain 14Fr and the circuit 49 for the refrigerant that cools the rear electric powertrain 14Rr.

[0058] The branch point of the second passage 40 and the bypass passage 44 is located downstream of the fifth heat exchanger 57, and is provided with a flow path switching valve 42. The flow path switching valve 42 switches whether the refrigerant that has passed through the fifth heat exchanger 57 flows directly through the second passage 40 or through the bypass passage 44.

[0059] The heat pump system 101C includes a circulation path in which a first heat exchanger 53, a compressor 55, a fifth heat exchanger 57, and an expansion valve 56 are arranged in this order. The compressor 55 can rotate in either the forward direction, which is the direction of rotation when the refrigerant that has passed through the first heat exchanger 53 is compressed and sent to the fifth heat exchanger 57, or the reverse direction, which is the direction of rotation when the refrigerant that has passed through the fifth heat exchanger 57 is compressed and sent to the first heat exchanger 53.

[0060] The pumps 52, 43, 48, 50, compressor 55, and flow path switching valve 42 are controlled by the controller 13. In the warm-up mode, the controller 13 operates the first refrigerant pump 52, the second refrigerant pump 43, and the fourth pump 50, rotates the compressor 55 in the reverse direction, and sets the flow path switching valve 42 to a state where refrigerant in the second circuit 101B passes through the bypass passage 44. As a result, heat generated in the rear electric powertrain 14Rr is transferred to the first circuit 101A via the heat pump system 101C and is used to warm up the battery 10. In addition, during the warm-up mode, the first refrigerant pump 52, the second refrigerant pump 43, the fourth pump 50, and the compressor 55 are driven using surplus power supplied from the external charger 15 as an external power source that cannot be fully absorbed by the battery 10 due to input / output limitations caused by low temperatures.

[0061] In the warm-up mode, the efficiency of boosting the power from the external charger 15 is reduced, thereby increasing copper loss and causing the rotating electric machine 12 to generate heat, and the heat is supplied to the battery 10 via the refrigerant, thereby raising the temperature of the battery 10.

[0062] 9 shows the results of verifying the warm-up promotion effect of the warm-up mode using a physical model. The warm-up promotion effect is calculated based on the temperature and charge amount of the battery 10. For comparison, the same model was also used to calculate the warm-up effect in both the high-efficiency mode and the d-axis current control.

[0063] The physical model used here uses the power input from the external charger 15 as an input and calculates the temperature rise due to the heat of the rotating electrical machine 12 and the inverter 11, the self-temperature rise due to the internal resistance of the battery 10, and the amount of power supplied to the battery 10. In the calculation, the battery temperature at the start of temperature rise was set to the temperature when the battery was soaked for a sufficient period of time in an extremely low temperature environment (for example, about -20°C), and the battery charge amount was set to about 10 kWh.

[0064] The calculation results show that in the high-efficiency mode, the rate of increase in battery temperature increases from time T2, and accordingly, the rate of increase in charge amount also increases, whereas in the warm-up mode, the rate of increase in battery temperature increases from time T1, which is earlier than the high-efficiency mode, and the rate of increase in charge amount also increases. Compared to these, the rate of increase in battery temperature is slower in the d-axis energization. Furthermore, in the d-axis energization, the rotating electrical machine 12 and inverter 11 are used as a boost converter and cannot boost voltage, so charging does not occur.

[0065] As described above, the battery temperature can be increased quickly by performing the warm-up mode.

[0066] 10 is a flowchart showing a control routine for controlling switching between the warm-up mode and the high-efficiency mode, which is executed by the controller 13. This control routine is pre-programmed in the controller 13.

[0067] In step S100, the controller 13 detects the battery temperature T ｂａｔｔ is the threshold T ｔｈ If it is lower, the process of step S110 is executed, and the threshold T ｔｈ In the above cases, the process of step S130 is executed. ｔｈ is a temperature at which the battery 10 can ensure sufficient input and output power, and is set according to the specifications of the battery 10. In this embodiment, it is set to about 25°C, for example.

[0068] In step S110, the controller 13 executes the warm-up mode.

[0069] In step S120, the controller 13 again detects the battery temperature T ｂａｔｔ is the threshold T ｔｈ If it is lower, the process returns to step S110 and the threshold T ｔｈ In the above cases, the process of step S130 is executed.

[0070] In step S130, the controller 13 executes the high efficiency mode.

[0071] That is, the controller 13 determines whether the battery temperature Tbatt is equal to or exceeds the threshold T ｔｈ While the U-phase current I Ｕis set to a low current close to zero, and the V-phase current I Ｖ and W-phase current I Ｗ This generates heat due to copper loss, and the heat is used to warm up the battery 10. Note that although loss (copper loss) increases in the warm-up mode, the warm-up mode is executed only when the battery temperature T ｂａｔｔ Since the input and output power is limited due to the low

[0072] Then, the threshold T ｔｈ When this is reached, that is, when the warm-up of the battery 10 is completed, the U-phase current I Ｕ and the V-phase current I Ｖ and W-phase current I Ｗ This reduces copper loss in the V-phase coil and the W-phase coil, suppressing heat generation and improving charging efficiency. In the high-efficiency mode, the V-phase current I Ｖ and W-phase current I Ｗ The U-phase current I Ｕ Since the current command value is increased, the total current value used for charging does not change. The current values ​​are switched by changing the current command value. In this case, the current command value may be switched in a stepwise manner or may be changed at a predetermined rate.

[0073] As described above, in this embodiment, a charging control method for an electric vehicle is provided, in which the electric drive system includes a battery 10, a rotating electric machine 12 whose rotor is equipped with three-phase coils and permanent magnets, and an inverter 11 interposed between the battery 10 and the rotating electric machine 12, and the electric drive system includes a rotating electric machine and inverter, and the electric drive system includes the battery 10, a rotating electric machine 12 whose rotor is equipped with three-phase coils and permanent magnets, and the inverter 11 is interposed between the battery 10 and the rotating electric machine 12. In this method, when warming up of the battery 10 is required, the controller 13 controls the current value (I Ｕ ) is set to a first current value that is greater than zero and is the smallest current value in a controllable range, and the current values ​​(I Ｖ , I Ｗa first mode in which the current value (I ) of the current flowing through two phase coils (V-phase coil and W-phase coil) of the three phase coils is set to a second current value that is a current value greater than the first current value, or Ｖ , I Ｗ ) is the first current value, and the current value (I Ｕ In either the first mode or the second mode, the current value flowing through the coil of one or two phases is reduced to increase heat loss (heat generation in the coil) due to copper loss, and this heat can be used to promote warm-up of the battery 10.

[0074] In this embodiment, the controller 13 detects the temperature T ｂａｔｔ Whether or not the first battery 10 needs to be warmed up is determined based on the battery temperature T. This makes it possible to appropriately determine whether or not the first battery 10 needs to be warmed up, and to set the first current value according to the state of the battery 10. In the above embodiment, whether or not the first battery 10 needs to be warmed up is determined based on the battery temperature T. ｂａｔｔ The judgment is based on the battery temperature T ｂａｔｔ Instead of this, the determination may be made based on the output of the battery 10. In this case, if the input / output power of the battery 10 is limited, it is determined that warm-up is necessary.

[0075] In this embodiment, the temperature of the battery 10 is increased by supplying the refrigerant, which has been heated by heat exchange with the inverter 11 and the rotating electrical machine 12, to the battery 10. This allows the battery 10 to be quickly warmed up without providing a heater or the like that is used only for warming up the battery 10.

[0076] In this embodiment, the circulation devices (pumps and compressors) 43, 50, 52, and 55 used to supply the refrigerant are driven by surplus power that cannot be fully absorbed by the battery 10 among the power supplied from the external charger 15. This allows the battery 10 to be warmed up without consuming power from the batteries for the headlamps, various meters, and other electrical equipment.

[0077] In this embodiment, once the warm-up of the battery 10 is complete, the first current value is increased and the second current value is decreased. By decreasing the second current value, copper loss in the coil through which the second current value flows can be suppressed, thereby improving charging efficiency. Furthermore, by increasing the first current value, the total current value used for charging can be maintained.

[0078] In this embodiment, the temperature of the battery 10 is determined based on the temperature of the refrigerant after heat exchange with the battery 10. This allows the temperature of the battery 10 to be determined with high accuracy.

[0079] Next, a modification of the above-described embodiment will be described. This modification, like the above-described embodiment, also falls within the scope of the present invention. This modification differs from the above-described embodiment in the current values ​​of each layer in the warm-up mode. The following description will focus on this difference.

[0080] 11 is a time chart of the current value when the warm-up mode is executed in the modified example. In the warm-up mode of this modified example, the total current value used for charging is the same as in the above embodiment, and the V-phase current I Ｖ and W-phase current I Ｗ is the lowest controllable current value. In other words, most of the total current value flows to the U-phase coil. In this case, only the U-phase coil contributes to warm-up, but the U-phase current I Ｕ Since the copper loss increases accordingly, the warm-up effect of the battery 10 can be ensured.

[0081] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A charging control method for an electric vehicle, comprising: a battery; a rotating electric machine whose rotor is equipped with a three-phase coil and a permanent magnet; and an inverter interposed between the battery and the rotating electric machine, and using the rotating electric machine and the inverter of an electric drive system to boost power supplied from an external power source and charge the battery, wherein, when it is necessary to warm up the battery, a controller performs charging in either of the warm-up modes: a first mode in which a current value of a current flowing through one of the three coils is set to a first current value that is greater than zero and is the smallest current value in a controllable range, and a current value of a current flowing through the other two coils is set to a second current value that is greater than the first current value, or a second mode in which a current value of a current flowing through two of the three coils is set to the first current value, and a current value of a current flowing through the other one coil is set to the second current value.

2. A method for controlling charging of an electric vehicle as described in claim 1, wherein the controller determines whether or not warming up of the battery is required based on the temperature or output of the battery.

3. A method for controlling charging of an electric vehicle as claimed in claim 1, wherein the battery is heated by supplying to the battery a refrigerant heated by heat exchange with the inverter and the rotating electric machine.

4. A charging control method for an electric vehicle as described in claim 3, wherein a circulation device used to supply the refrigerant is driven by surplus power that cannot be absorbed by the battery among the power supplied from the external power source.

5. The method for controlling charging of an electric vehicle as claimed in claim 1, wherein, when warm-up of the battery is completed, the first current value is increased and the second current value is decreased.

6. A method for controlling charging of an electric vehicle as claimed in claim 5, wherein the temperature of the battery is determined based on the temperature of a refrigerant after heat exchange with the battery.

7. A charging control device for an electric vehicle comprising: an electric drive system including: a battery; a rotating electric machine whose rotor is equipped with a three-phase coil and a permanent magnet; and an inverter interposed between the battery and the rotating electric machine and having the function of converting direct current supplied from the battery into three-phase alternating current; and a controller that performs charging control to boost power supplied from an external power source using the rotating electric machine and the inverter to charge the battery, wherein, when warming up of the battery is required, the controller performs charging in either a first mode in which a current value of a current flowing through one of the three coils is set to a first current value that is greater than zero and is the smallest current value in a controllable range, and a current value of a current flowing through the other two coils is set to a second current value that is greater than the first current value, or a second mode in which a current value of a current flowing through two of the three coils is set to the first current value, and a current value of a current flowing through the other one coil is set to the second current value.

Images