Electric vehicle

Abstract

To provide an electric vehicle capable of charging a battery with a high-voltage external power supply without using an independent step-down converter.SOLUTION: An electric vehicle disclosed herein may comprise a battery, a motor, first and second inverters, a power receiving terminal, and a controller. The motor includes a plurality of stator coils, a first inverter is connected to one ends of the plurality of stator coils, and a second inverter is connected to the other ends of the plurality of stator coils. The power receiving terminal includes a connection positive electrode terminal and a connection negative electrode terminal to which an external power supply is connectable. When the external power supply is connected to the power receiving terminal, the controller turns on and off the second upper switching element while keeping the first lower switching element off. The second upper switching element and the stator coil function as a step-down circuit, and the voltage of the external power supply is stepped down and reaches the battery. The battery can be charged by a high-voltage external power supply.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an electric vehicle that uses a stator coil of a motor and switching elements of an inverter as a step-down circuit and can charge a battery with a high-voltage external power supply. [Background technology]

[0002] Patent Document 1 discloses an electric vehicle equipped with a step-down converter so that the battery can be charged by an external power supply that has a higher output voltage than the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-061691 Summary of the Invention [Problem to be solved by the invention]

[0004] An electric vehicle includes a motor and an inverter. This specification provides an electric vehicle that utilizes the stator coil of the motor and the switching elements of the inverter as a step-down circuit, and that can charge the battery from a high-voltage external power supply without having an independent step-down converter. [Means for solving the problem]

[0005] The electric vehicle disclosed in this specification includes a battery, a motor, first and second inverters, a power receiving terminal, and a controller. The motor includes multiple stator coils, one end of which is connected to a first inverter, and the other end of which is connected to a second inverter. The power receiving terminal includes a positive power receiving terminal and a negative power receiving terminal to which an external power supply can be connected. An external power supply with an output voltage higher than that of the battery can be connected to the power receiving terminal.

[0006] The first inverter includes a first high potential terminal, a first ground terminal, and a plurality of first series-connected bodies connected in parallel therebetween. Each first series-connected body includes a first upper switching element and a first lower switching element connected in series. One end of each stator coil is connected to the midpoint of each first series-connected body (the connection point between the first upper switching element and the first lower switching element). The second inverter includes a second high potential terminal, a second ground terminal, and a plurality of second series-connected bodies connected in parallel therebetween. Each second series-connected body includes a second upper switching element and a second lower switching element connected in series. The other end of each stator coil is connected to the midpoint of each second series-connected body (the connection point between the second upper switching element and the second lower switching element).

[0007] The negative terminal of the battery is electrically connected to the first ground terminal, the second ground terminal, and the power receiving negative terminal. The positive terminal of the battery is connected to the first high potential terminal. The power receiving positive terminal is connected to the second high potential terminal. When an external power supply is connected to the power receiving terminal, the controller turns the second upper switching element on and off while keeping the first lower switching element off, thereby stepping down the voltage of the external power supply and charging the battery.

[0008] The electric vehicle disclosed in this specification can charge the battery from a high output voltage external power supply by utilizing the second upper switching element and the stator coil as a step-down circuit. The electric vehicle disclosed in this specification can charge the battery from a high output voltage external power supply without requiring an independent step-down converter.

[0009] Details and further improvements of the technology disclosed in this specification are described in the following "Description of Embodiments of the Invention." [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a circuit diagram of an electric vehicle according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing the flow of current during charging. DETAILED DESCRIPTION OF THE INVENTION

[0011] An electric vehicle 2 according to an embodiment will be described with reference to the drawings. Fig. 1 shows a circuit diagram of the electric vehicle 2. The electric vehicle 2 includes a battery 3, a first inverter 10, a second inverter 20, a motor 30, a connecting switch 4, a power receiving terminal 40, and a controller 5. Fig. 1 also shows an external power source 70 for charging the battery 3. The external power source 70 is installed in, for example, a charging station.

[0012] An axle (not shown) is connected to the output shaft of the motor 30. The motor 30 is driven by power from the battery 3, which drives the electric vehicle 2. The motor 30 is a three-phase AC motor and has a plurality of stator coils 31. The DC power of the battery 3 is converted by the first inverter 10 (and the second inverter 20) into AC power suitable for driving the motor 30, and is supplied to the motor 30 (stator coil 31).

[0013] The battery 3 can be charged by kinetic energy when the electric vehicle 2 decelerates, but can also be charged by an external power supply 70 connected to the power receiving terminal 40. When charging the battery 3 with the external power supply 70, the upper switching element (second upper switching element 22) of the second inverter 20 and the stator coil 31 of the motor 30 can be used as a step-down circuit. Therefore, in the electric vehicle 2, the battery 3 can be charged by the external power supply 70 even if the output voltage of the external power supply 70 is higher than the output voltage of the battery 3.

[0014] The configuration of the first inverter 10 will be described. The first inverter 10 has a first high potential terminal 10p, a first ground terminal 10g, and three sets of first series-connected bodies 11a, 11b, and 11c. The three sets of first series-connected bodies 11a, 11b, and 11c are connected in parallel between the first high potential terminal 10p and the first ground terminal 10g.

[0015] Each of the three sets of first series-connected bodies 11a, 11b, and 11c includes a first upper switching element 12 and a first lower switching element 13 connected in series. The first upper switching element 12 is connected to a first high potential terminal 10p, and the first lower switching element 13 is connected to a first ground terminal 10g. One end of each of the three stator coils 31 is connected to the midpoint of each of the three sets of first series-connected bodies 11a, 11b, and 11c (the connection point between the first upper switching element 12 and the first lower switching element 13).

[0016] A free wheel diode is connected in anti-parallel to each first upper switching element 12 and each first lower switching element 13. The free wheel diode always passes a current from the first ground terminal 10g side to the first high potential terminal 10p side. The free wheel diode may be an element separate from the first upper switching element 12 (first lower switching element 13), or may be a diode function included in the element of the first upper switching element 12 (first lower switching element 13).

[0017] A smoothing capacitor 15 is connected between the first high potential end 10p and the first ground end 10g. The smoothing capacitor 15 suppresses fluctuations in current / voltage caused by the on / off switching of the switching element.

[0018] The configuration of the second inverter 20 will be described. The second inverter 20 has a second high potential terminal 20p, a second ground terminal 20g, three sets of second series-connected bodies 21a, 21b, and 21c, and a smoothing capacitor 25. Each of the three sets of second series-connected bodies 21a, 21b, and 21c includes a second upper switching element 22 and a second lower switching element 23 connected in series. The other ends of the three stator coils 31 are connected to the midpoints of the three sets of second series-connected bodies 21a, 21b, and 21c (the connection points between the second upper switching elements 22 and the second lower switching elements 23). The configuration of the second inverter 20 is the same as that of the first inverter 10, so a detailed description will be omitted.

[0019] The positive electrode of the battery 3 (battery positive terminal 3p) is connected to the first high potential terminal 10p, and the negative electrode of the battery 3 (battery negative terminal 3n) is connected to the first ground terminal 10g. The battery negative terminal 3n is also connected to the second ground terminal 20g. A connecting switch 4 is connected between the first high potential terminal 10p and the second high potential terminal 20p to connect or disconnect the two. When the connecting switch 4 is closed, the first inverter 10 and the second inverter 20 are connected in parallel to the battery 3. When the connecting switch 4 is opened, the second inverter 20 is disconnected from the first inverter 10 and the battery 3.

[0020] All switching elements and the connecting switch 4 are controlled by a controller 5. When the controller 5 causes the motor 30 to output low or medium torque, it opens the connecting switch 4 and drives the first inverter 10 (the first upper switching element 12 and the first lower switching element 13). At this time, the controller 5 keeps the three second upper switching elements 22 of the second inverter 20 on. As a result, the other ends of the three stator coils 31 are mutually conductive, and the other ends of the three stator coils 31 are star-connected. At this time, the drive system of the electric vehicle 2 becomes a normal one-motor, one-inverter system and is driven only by the first inverter 10. The motor 30 is driven by the battery 3 and the first inverter 10 and outputs low or medium torque. For ease of explanation, driving the motor 30 only by the first inverter 10 is referred to as single-inverter mode.

[0021] When the controller 5 causes the motor 30 to output high torque, it closes the connecting switch 4 and drives the first inverter 10 (first upper switching element 12 and first lower switching element 13) and the second inverter 20 (second upper switching element 22 and second lower switching element 23). Specifically, the controller 5 drives the second upper switching element 22 so that its current is in the opposite phase to the movement of the first upper switching element 12, and drives the second lower switching element 23 so that its current is in the opposite phase to the movement of the first lower switching element 13. The current flowing through the motor 30 becomes roughly twice that in single inverter mode, and the motor 30 outputs high torque.

[0022] Charging of the battery 3 by the external power source 70 will now be described. The external power source 70 is connected to the power receiving terminal 40. The power receiving terminal 40 has a power receiving positive terminal 40p and a power receiving negative terminal 40n. The positive terminal 70p of the external power source 70 is connected to the power receiving positive terminal 40p, and the negative terminal 70n of the external power source 70 is connected to the power receiving negative terminal 40n. The power receiving negative terminal 40n is connected to the battery negative terminal 3n (and the first ground terminal 10g and the second ground terminal 20g). The power receiving positive terminal 40p is connected to the second high potential terminal 20p.

[0023] Normally, when the electric vehicle 2 is stopped (when the shift lever, not shown, is in the "P" range), the controller 5 opens the coupling switch 4. When the external power supply 70 is connected to the power receiving terminal 40 in this state, the controller 5 first checks the output voltage of the external power supply 70. The controller 5 measures the output voltage of the external power supply 70 using a voltage sensor, not shown. Alternatively, the controller 5 communicates with the external power supply 70 to obtain information about the output voltage.

[0024] When the output voltage of the external power supply 70 is equal to the voltage of the battery 3, the controller 5 closes the coupling switch 4. At this time, the battery 3 and the external power supply 70 are directly coupled, and the power of the external power supply 70 flows to the battery 3 without passing through the first inverter 10 and the second inverter 20, thereby charging the battery 3.

[0025] When the output voltage of the external power supply 70 is higher than the output voltage of the battery 3, the controller 5 keeps the connecting switch 4 open. The controller 5 turns the second upper switching element 22 on and off while keeping the first lower switching element 13 off. The second upper switching element 22 and the stator coil 31 function as a step-down circuit, and the output voltage of the external power supply 70 is stepped down and appears at the first high potential terminal 10p (i.e., the battery positive terminal 3p). The ratio (step-down ratio) between the voltage applied to the second high potential terminal 20p and the voltage appearing at the first high potential terminal 10p is determined by the duty ratio of the PWM signal that drives the second upper switching element 22. The controller 5 adjusts the duty ratio so that the voltage at the first high potential terminal 10p becomes a voltage suitable for charging the battery 3. It is well known that the second upper switching element 22 and the stator coil 31 function as a step-down circuit, so a detailed description of their operation will be omitted.

[0026] Note that the battery 3 can be charged no matter how high the output voltage of the external power supply 70 is. However, if the output voltage of the external power supply 70 is much higher than the voltage of the battery 3, the battery 3 will be damaged. The controller 5 adjusts the voltage of the first high potential end 10p (i.e., the voltage applied to the battery 3) so that current flows from the external power supply 70 to the battery 3 without causing significant damage to the battery 3.

[0027] FIG. 2 shows the current flow at this time. The circuit diagram in FIG. 2 is the same as that in FIG. 1. In FIG. 2, thick arrows indicate the current flow. The first upper switching element 12 may be on or off. This is because, even when the first upper switching element 12 is off, current can flow from the stator coil 31 to the first high potential terminal 10p (battery positive terminal 3p) through the freewheeling diode. The second lower switching element 23 is kept off at least when the second upper switching element 22 is on. The current that passes through the second upper switching element 22 does not flow to the second ground terminal 20g, but flows to the stator coil 31.

[0028] 2, current flows from the positive terminal 70p of the external power supply 70 through the power receiving positive terminal 40p, the second high potential terminal 20p, the second upper switching element 22, the stator coil 31, the first upper switching element 12 (or a diode associated therewith), the first high potential terminal 10p, and to the battery 3. The battery negative terminal 3n is connected to the negative terminal 70n of the external power supply 70 through the power receiving negative terminal 40n.

[0029] 2, the voltage of the external power supply 70 is stepped down and reaches the battery positive terminal 3p, and the battery 3 is charged with the power from the external power supply 70. The electric vehicle 2 of the embodiment can charge the battery 3 with the high-voltage external power supply 70 without using an independent step-down converter.

[0030] Some of the features of the electric vehicle 2 of the embodiment are listed below. The electric vehicle 2 includes a battery 3, a first inverter 10, a second inverter 20, a motor 30, a power receiving terminal 40, and a controller 5. One end of each of three stator coils 31 is connected to the midpoint (the connection point between the first upper switching element 12 and the first lower switching element 13) of each of the three sets of first series-connected bodies 11a, 11b, and 11c of the first inverter 10. The other end of each of the three stator coils 31 is connected to the midpoint (the connection point between the second upper switching element 22 and the second lower switching element 23) of each of the three sets of second series-connected bodies 21a, 21b, and 21c of the second inverter 20.

[0031] The electric vehicle 2 further includes a connecting switch 4 that connects or disconnects the first high potential terminal 10p and the second high potential terminal 20p. The battery negative terminal 3n, the first ground terminal 10g, the second ground terminal 20g, and the power receiving negative terminal 40n of the power receiving terminal 40 are mutually conductive. The battery positive terminal 3p is connected to the first high potential terminal 10p, and the power receiving positive terminal 40p of the power receiving terminal 40 is connected to the second high potential terminal 20p. When an external power source 70 with a higher output voltage than the battery 3 is connected to the power receiving terminal 40, the controller 5 turns the second upper switching element 22 on and off while keeping the first lower switching element 13 off, thereby reducing the voltage of the external power source 70 and charging the battery 3. At this time, the first upper switching element 12 may be on or off. The second lower switching element 23 is preferably kept off. However, it is sufficient that the second lower switching element 23 is off at least when the second upper switching element 22 is on.

[0032] When the output voltage of the external power supply 70 is equal to the output voltage of the battery 3 (in other words, when the output voltage of the external power supply 70 is a voltage suitable for charging the battery 3), the controller 5 closes the coupling switch 4 and keeps all switching elements of the first inverter 10 and the second inverter 20 off. The power of the external power supply 70 is supplied to the battery 3 without passing through the first inverter 10 and the second inverter 20.

[0033] Here are some points to note regarding the technology described in the examples. The technology disclosed in this specification can be applied not only to electric vehicles that do not have engines, but also to hybrid vehicles that have a battery, a motor, and an engine. In other words, the term "electric vehicle" in this specification refers to any vehicle that has a motor and a battery for driving, and can also include hybrid vehicles.

[0034] 2, the controller 5 simultaneously turns on and off all of the second upper switching elements 22. When charging the battery 3 with a high-voltage external power supply 70, the controller 5 may turn on and off one or two second upper switching elements 22 and keep the remaining second upper switching elements 22 off.

[0035] The expression "holding a switching element on" is equivalent to "closing a switching element," which means electrically connecting a device connected to each end of the switching element. The expression "holding a switching element off" is equivalent to "opening a switching element," which means electrically disconnecting a device connected to each end of the switching element.

[0036] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives alone is technically useful. [Explanation of symbols]

[0037] 2: Electric vehicle 3: Battery 4: Link switch 5: Controller 10: First inverter 12, 13, 22, 23: Switching elements 15, 25: Smoothing capacitor 20: Second inverter 30: Motor 31: Stator coil 40: Power receiving terminal 70: External power supply

Claims

[Claim 1] An electric vehicle that can charge the battery using an external power source that has a higher output voltage than the battery, a motor having a plurality of stator coils; a first inverter connected to one end of the plurality of stator coils; a second inverter connected to the other ends of the plurality of stator coils; a power receiving terminal having a power receiving positive terminal and a power receiving negative terminal to which the external power source can be connected; A controller; It is equipped with The first inverter is a first high potential end; a first ground end; a plurality of first series-connected bodies in which first upper switching elements and first lower switching elements are connected in series, the plurality of first series-connected bodies being connected in parallel between the first high potential end and the first ground end; It is equipped with One end of each of the stator coils is connected to a midpoint of each of the first series-connected bodies, The second inverter is A second high potential end; a second ground end; a plurality of second series-connected bodies in which second upper switching elements and second lower switching elements are connected in series, the plurality of second series-connected bodies being connected in parallel between the second high potential end and the second ground end; It is equipped with The other end of each of the stator coils is connected to a midpoint of each of the second series-connected bodies, the negative electrode of the battery, the first ground terminal, the second ground terminal, and the power receiving negative terminal are electrically connected to each other; the positive electrode of the battery is connected to the first high potential terminal; the power receiving positive terminal is connected to the second high potential terminal, When the external power supply is connected to the power receiving terminal, the controller turns on and off the second upper switching element while keeping the first lower switching element off, thereby stepping down the voltage of the external power supply and charging the battery. Electric car.

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