Charging system

Abstract

The present application relates to a charging system configured to transform a voltage of a power supply to charge a battery, the charging system comprising: a motor having a plurality of stator coils; a power receiving terminal having a power receiving positive electrode end and a power receiving negative electrode end to which the power source can be connected, the power receiving negative electrode end being connected to a battery negative electrode end of the battery, and the power receiving positive electrode end being connected to a neutral point of the motor; a capacitor connected between the power receiving positive electrode terminal and the power receiving negative electrode terminal; an inverter, the DC end of which is connected to the battery and the AC end of which is connected to a first end of one end of the plurality of stator coils; a plurality of neutral point switching elements, each of which connects a second end of the other end of each of the plurality of stator coils to the neutral point; and a plurality of diodes, each of which has a positive electrode connected to the power receiving negative electrode end and a negative electrode connected to a second end of the other end of each of the plurality of stator coils.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a charging system that includes an inverter and a motor and can use the switching elements of the inverter and the stator coils of the motor as a voltage converter to charge a battery. Background Art

[0002] It is publicly known that a circuit using the stator coils of a motor and the switching elements of an inverter can be used as a boost converter. Japanese Patent Application Laid-Open No. 2023-114972 discloses a device that uses the stator coils of a motor and the lower switching elements of an inverter as a boost converter to charge a battery with a power source having an output voltage lower than that of the battery.

[0003] In the device of Japanese Patent Application Laid-Open No. 2023-114972, when charging the battery, the other ends of a plurality of stator coils are connected to each other at the neutral point, and a power source is connected to the neutral point. The current of the power source flows through the neutral point to the stator coils. By turning on and off the lower switching elements of the first inverter, the voltage of the power source is boosted by the stator coils. The power of the power source flows through the neutral point / stator coils / upper switching elements of the first inverter to the battery. Hereinafter, for convenience of explanation, the charging method of delivering power to the battery through the neutral point is referred to as neutral point charging. Summary of the Invention

[0004] In the system of Japanese Patent Application Laid-Open No. 2023-114972, it is impossible to step down the power source voltage to deliver power to the battery. This specification provides a charging system that uses the stator coils of a motor as a reactor and can charge the battery with either a power source having an output voltage lower than that of the battery or a power source having an output voltage higher than that of the battery.

[0005] The charging system according to the first aspect of the present disclosure is a charging system configured to transform the voltage of a power source to charge a battery, and includes: a motor having a plurality of stator coils; a power receiving terminal having a power receiving positive terminal and a power receiving negative terminal configured to be connected to the power source, the power receiving negative terminal being connected to the battery negative terminal of the battery, and the power receiving positive terminal being connected to the neutral point of the motor; a capacitor connected between the power receiving positive terminal and the power receiving negative terminal; an inverter having a DC terminal connected to the battery and an AC terminal connected to the first ends of the plurality of stator coils; a plurality of neutral point switching elements, each of the neutral point switching elements connecting the second ends of the plurality of stator coils to the neutral point; and a plurality of diodes, the positive electrode of each of the diodes being connected to the power receiving negative terminal and the negative electrode being connected to the second ends of the plurality of stator coils.

[0006] The charging system according to the first aspect of the present disclosure may further include a controller. The controller may be configured to: when the output voltage of the power source connected to the power receiving terminal is lower than the output voltage of the battery, close a plurality of neutral point switching elements, turn on and off the lower switching elements of the inverter, boost the voltage of the power source, and charge the battery. The voltage of the power source is boosted by the stator coil, and the battery can be charged using a power source with an output voltage lower than that of the battery. The controller may be configured to: when the output voltage of the power source connected to the power receiving terminal is higher than the output voltage of the battery, turn on and off the neutral point switching elements to step down the voltage of the power source and charge the battery. The voltage of the power source is stepped down by the stator coil, and the battery can be charged using a power source with an output voltage higher than that of the battery.

[0007] In the charging system according to the first aspect of the present disclosure, the controller may be configured to: when driving the motor using the battery in a state where the power source is not connected to the power receiving terminal, close a plurality of the neutral point switching elements, and turn on and off the upper and lower switching elements of the inverter.

[0008] The charging system according to the first aspect of the present disclosure may further include a direct charging switch that connects the positive power receiving terminal to the positive battery terminal bypassing the stator coil.

[0009] The charging system according to the first aspect of the present disclosure may further include a sub-inverter having a DC terminal connected to the battery and an AC terminal connected to the second ends of a plurality of the stator coils.

[0010] The detailed technology and further improvements disclosed in this specification will be described in the following "Detailed Description of the Embodiments". BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Hereinafter, the features, advantages, technology, and industrial importance of the exemplary embodiments of the present invention will be described with reference to the drawings, in which the same reference numerals denote the same components, where:

[0012] Figure 1 is a circuit diagram of the charging system of the first embodiment.

[0013] Figure 2 is a circuit diagram of the charging system of the second embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] (First Embodiment)

[0015] The charging system 2 of the first embodiment will be described with reference to the drawings. Figure 1The circuit diagram of the charging system 2 of the first embodiment is shown. The charging system 2 includes a first inverter 10, a second inverter 20, a motor 30, a plurality of neutral point switching elements 32, a plurality of diodes 33, a power receiving terminal 40, and a controller 50. Figure 1 In addition to depicting the charging system 2, a battery 60 and an external power source 70 are also depicted. The external power source 70 can be attached to and detached from the power receiving terminal 40.

[0016] The outline of the charging system 2 will be described. The charging system 2 can charge the battery 60 through the external power source 70 connected to the power receiving terminal 40. When charging the battery 60, the lower switching element of the first inverter 10 and the stator coil 31 of the motor 30 function as a boost converter. Therefore, the battery 60 can be charged by the external power source 70 whose output voltage is lower than that of the battery 60. In addition, the neutral point switching element 32, the stator coil 31, and the diode 33 function as a buck converter. Therefore, even when the output voltage of the external power source 70 is higher than the output voltage of the battery 60, the battery 60 can be charged.

[0017] The charging system 2 and the battery 60 are mounted on an electric vehicle. The motor 30 is connected to an axle (not shown) of the electric vehicle, and the charging system 2 also functions as a drive system that drives the motor 30 using the power of the battery 60 to make the electric vehicle run. The motor 30 is a three-phase AC motor and has a plurality of stator coils 31. The charging system 2 can drive the motor 30 only when the external power source 70 is not connected to the power receiving terminal 40. Next, the details of the charging system 2 will be described.

[0018] The configuration of the first inverter 10 will be described. The battery 60 is connected to the DC terminal of the first inverter 10, and one end of the stator coil 31 (which can be regarded as the first terminal in this application) is connected to the AC terminal. The first inverter 10 has 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 positive terminal (battery positive terminal 60p) and the negative terminal (battery negative terminal 60n) of the battery 60. The high-potential side and the low-potential side of the first series-connected bodies 11a, 11b, and 11c correspond to the DC terminal of the first inverter 10.

[0019] Each of the three sets of first series connection 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 the positive electrode terminal 60p of the battery, and the first lower switching element 13 is connected to the negative electrode terminal 60n of the battery. One end of each of the three stator coils 31 is connected to the midpoint (the connection point of the first upper switching element 12 and the first lower switching element 13) of each of the three sets of first series connection bodies 11a, 11b, and 11c. If the controller 50 alternately turns on and off the first upper switching element 12 and the first lower switching element 13, an alternating current is output from the midpoint. The midpoints of the first series connection bodies 11a, 11b, and 11c correspond to the AC terminals of the first inverter 10.

[0020] The configuration of the second inverter 20 will be described. The battery 60 is connected to the DC terminal of the second inverter 20, and the other end of the stator coil 31 (which can be regarded as the second terminal in this application) is connected to the AC terminal. The second inverter 20 has three sets of second series connection bodies 21a, 21b, and 21c. The three sets of second series connection bodies 21a, 21b, and 21c are connected in parallel between the positive electrode terminal 60p and the negative electrode terminal 60n of the battery. The high potential side and the low potential side of the second series connection bodies 21a, 21b, and 21c correspond to the DC terminals of the second inverter 20.

[0021] Each of the three sets of second series connection bodies 21a, 21b, and 21c includes a second upper switching element 22 and a second lower switching element 23 connected in series. The second upper switching element 22 is connected to the positive electrode terminal 60p of the battery, and the second lower switching element 23 is connected to the negative electrode terminal 60n of the battery. The other end of each of the three stator coils 31 is connected to the midpoint (the connection point of the second upper switching element 22 and the second lower switching element 23) of each of the three sets of second series connection bodies 21a, 21b, and 21c. If the controller 50 alternately turns on and off the second upper switching element 22 and the second lower switching element 23, an alternating current is output from the midpoint. The midpoints of the second series connection bodies 21a, 21b, and 21c correspond to the AC terminals of the second inverter 20.

[0022] Freewheeling diodes are connected in anti-parallel to the respective switching elements of the first inverter 10 and the second inverter 20. The freewheeling diodes can be elements different from the switching elements, or can be diode elements included in the switching elements.

[0023] The charging system 2 includes a plurality of neutral point switching elements 32. Each of the plurality of neutral point switching elements 32 connects the other end of each of the plurality of stator coils 31 to the neutral point 34. If the plurality of neutral point switching elements 32 are closed, the plurality of stator coils 31 are electrically connected to each other at the neutral point 34. If the plurality of neutral point switching elements 32 are opened, the plurality of stator coils 31 are electrically separated from the neutral point 34.

[0024] A freewheeling diode is anti-parallel connected to each of the multiple neutral point switch elements 32. The freewheeling diode can be an element different from the neutral point switch element 32 or a diode element included in the neutral point switch element 32.

[0025] The charging system 2 is provided with a power receiving terminal 40. The power receiving terminal 40 has a power receiving positive terminal 40p for connecting to the positive electrode 70p of the external power supply 70 and a power receiving negative terminal 40n for connecting to the negative electrode 70n of the external power supply 70. A capacitor 41 is connected between the power receiving positive terminal 40p and the power receiving negative terminal 40n. In addition, a capacitor 61 is connected between the battery positive terminal 60p and the battery negative terminal 60n.

[0026] The charging system 2 is provided with a pair of charging switches 35. One charging switch 35 is connected between the neutral point 34 and the power receiving positive terminal 40p, and the other charging switch 35 is connected between the positive electrodes of the multiple diodes 33 and the power receiving negative terminal 40n. The charging switch 35 is provided to completely disconnect the power receiving terminal 40 from the stator coil 31.

[0027] As described previously, the charging system 2 also functions as a drive system for driving the motor 30 using the power of the battery 60. The controller 50 closes the multiple neutral point switch elements 32. If the neutral point switch elements 32 are closed, the other ends of the multiple stator coils 31 are connected to each other at the neutral point 34.

[0028] If the neutral point switch elements 32 are closed, the motor 30 functions as a closed-type motor with the other end Y-connected. The controller 50 stops the second inverter 20 and appropriately turns on and off the first upper switch element 12 and the first lower switch element 13 of the first inverter 10. Alternating current is supplied from the AC terminal of the first inverter 10 to the stator coil 31, and the motor 30 rotates.

[0029] When the motor 30 is driven by two inverters (the first inverter 10 and the second inverter 20), the controller 50 disconnects the multiple neutral point switch elements 32. One end of the stator coil 31 of the motor 30 is connected to the AC terminal of the first inverter 10, and the other end is connected to the AC terminal of the second inverter 20. The motor 30 functions as an open-type motor. If the controller 50 appropriately turns on and off the respective switch elements of the first inverter 10 and the second inverter 20, the motor 30 rotates. At this time, since the motor 30 is driven by the two inverters 10 and 20, a higher torque can be output compared to the case where only the first inverter 10 is used for driving.

[0030] Among them, the driving motor 30 is limited to the case where the external power supply 70 is not connected to the power receiving terminal 40. If the external power supply 70 is connected in the case of the driving motor 30, there is a concern that an inappropriate current may flow in the charging system 2. Therefore, in the case of the driving motor 30, a pair of charging switches 35 are disconnected, and the neutral point 34 and the diode 33 are completely separated from the power receiving terminal 40.

[0031] The charging system 2 can charge the battery 60 in either case where the output voltage of the external power supply 70 is higher or lower than the output voltage of the battery. Among them, before charging the battery 60, the controller 50 closes a pair of charging switches 35.

[0032] First, the operation of the controller 50 in the case where the output voltage of the external power supply 70 connected to the power receiving terminal 40 is lower than the output voltage of the battery 60 will be described.

[0033] When the external power supply 70 with an output voltage lower than that of the battery 60 is connected to the power receiving terminal 40, the controller 50 closes a plurality of neutral point switch elements 32. Moreover, the controller 50 appropriately turns on and off a plurality of first lower switch elements 13 of the first inverter 10. When the controller 50 turns on the first lower switch element 13, current flows from the external power supply 70 through the neutral point switch element 32, the stator coil 31, and the first lower switch element 13 to the capacitor 61, and magnetic energy is stored in the stator coil 31. When the controller 50 switches the first lower switch element 13 from on to off, the magnetic energy of the stator coil 31 is released, and current is pushed out from the stator coil 31 toward the positive battery terminal 60p through the induced electromotive force. At this time, the voltage of the external power supply 70 is boosted. Current flows from the external power supply 70 through the neutral point switch element 32, the stator coil 31, and the freewheeling diode of the first upper switch element 12 to the battery 60. That is, the battery 60 is charged using the external power supply 70 with an output voltage lower than that of the battery 60.

[0034] Next, the operation of the controller 50 in the case where the output voltage of the external power supply 70 connected to the power receiving terminal 40 is higher than the output voltage of the battery 60 will be described. In this case, the controller 50 appropriately turns on and off the neutral point switch element 32. When the controller 50 closes the neutral point switch element 32, current flows from the external power supply 70 through the neutral point switch element 32, the stator coil 31, and the freewheeling diode of the first upper switch element 12 to the battery 60. At the same time, magnetic energy is stored in the stator coil 31.

[0035] If the controller 50 switches the neutral point switching element 32 from conducting to non-conducting, the current from the external power source 70 to the battery 60 stops. At the same time, the magnetic energy stored in the stator coil 31 is released. The released magnetic energy generates an induced electromotive force, and the stator coil 31 extracts charge from the capacitor 41 through the diode 33 and delivers it to the battery 60. That is, the neutral point switching element 32, the stator coil 31, and the capacitor 41 function as a buck converter. The battery 60 is charged by the external power source 70 whose output voltage is higher than that of the battery 60.

[0036] The charging system 2 is provided with a direct charging switch 37 that connects the power receiving positive terminal 40p to the battery positive terminal 60p bypassing the stator coil 31. When the output voltage of the external power source 70 connected to the power receiving terminal 40 is equal to the output voltage of the battery 60, the controller 50 closes the direct charging switch 37. The external power source 70 is directly connected to the battery 60. In this case, the current bypasses the stator coil 31 and the switching element and flows from the external power source 70 to the battery 60. By charging the battery 60 via the direct charging switch 37, the charging loss can be suppressed to a low level.

[0037] (Second Embodiment)

[0038] Figure 2 The circuit diagram of the charging system 102 of the second embodiment is shown. In the charging system 102, the diode 33 of the charging system 2 of the first embodiment is replaced with an additional switching element 133. Other configurations of the charging system 102 are the same as those of the charging system 2 of the first embodiment.

[0039] The additional switching element 133 is accompanied by a freewheeling diode 133a. The positive electrode of each freewheeling diode 133a is connected to the power receiving negative terminal 40n, and the negative electrode is connected to the other end of each stator coil 31. The freewheeling diode is responsible for the same function as the diode 33 of the charging system 2 of the first embodiment. Therefore, when the additional switching element 133 is turned off, the charging system 102 operates in the same manner as the charging system 2 and provides the same advantages.

[0040] The advantages are described due to the presence of the additional switching element 133. An electrical device that consumes electric power is connected to the power receiving terminal 40 instead of the external power source. If a pair of charging switches 35 are closed and the additional switching element 133 is appropriately turned on and off, the voltage of the battery 60 is boosted and output to the power receiving terminal 40. That is, the charging system 102 having the additional switching element 133 functions as a power source that can boost the output voltage of the battery 60 and output it to the outside.

[0041] In addition, an electrical device that consumes power is connected to the power receiving terminal 40, and a pair of charging switches 35 and the neutral point switching element 32 are closed. If the first upper switching element 12 is appropriately turned on and off, the voltage of the battery 60 is stepped down by the stator coil 31 and output from the power receiving terminal 40. That is, the charging system 102 can also step down the output voltage of the battery 60 and output it to the outside.

[0042] Enumerate several features of the charging system 2 (102) described in the embodiments. A battery 60 is connected to the DC side of the first inverter 10, and a plurality of stator coils 31 are connected to the AC side. The power receiving terminal 40 includes a power receiving positive terminal 40p and a power receiving negative terminal 40n, and an external power supply 70 can be connected to them. The power receiving negative terminal 40n is connected to the battery negative terminal 60n, and the power receiving positive terminal 40p is connected to the neutral point 34 of the motor 30. A capacitor 41 is connected between the power receiving positive terminal 40p and the power receiving negative terminal 40n. Each of the plurality of neutral point switching elements 32 connects the other end of each of the plurality of stator coils 31 to the neutral point 34. The positive electrode of each of the plurality of diodes 33 is connected to the power receiving negative terminal 40n, and the negative electrode is connected to the other end of each of the plurality of stator coils 31. With this structure, the battery 60 can be charged regardless of whether the output voltage of the external power supply 70 is higher or lower than the output voltage of the battery 60. The first inverter 10 is an example of an "inverter". The external power supply 70 is an example of a "power supply".

[0043] When the output voltage of the external power supply 70 connected to the power receiving terminal 40 is lower than the output voltage of the battery 60, the controller 50 closes the plurality of neutral point switching elements 32. Moreover, the controller 50 turns on and off the first lower switching element 13 of the first inverter 10. As a result, the voltage of the external power supply 70 is boosted to the voltage of the battery 60. The power of the external power supply 70 is supplied to the battery 60 to charge the battery 60. When the output voltage of the external power supply 70 connected to the power receiving terminal 40 is higher than the output voltage of the battery 60, the controller 50 turns on and off the neutral point switching element 32. As a result, the voltage of the external power supply 70 is stepped down to the voltage of the battery 60. The power of the external power supply 70 is supplied to the battery 60 to charge the battery 60.

[0044] In a state where the external power supply 70 is not connected to the power receiving terminal 40, when driving the motor 30 using the battery 60, the controller 50 closes the plurality of neutral point switching elements 32. Moreover, the controller 50 alternately turns on and off the first upper switching element 12 and the first lower switching element 13 of the first inverter 10. The motor 30 is driven by this operation.

[0045] The charging system 2 (102) may include a direct charging switch 37 that bypasses the stator coil 31 and connects the positive power receiving terminal 40p to the positive battery terminal 60p. The charging system 2 (102) may also include a second inverter 20 (auxiliary inverter) whose DC terminal is connected to the battery 60 and whose AC terminal is connected to the other ends of the plurality of stator coils 31.

[0046] Points to note regarding the technology described in the embodiments are described. There may not be a pair of charging switches 35. The pair of charging switches 35 is provided to prevent malfunction in the case of accidentally driving the motor 30 while the external power supply 70 is connected.

[0047] There may also be no second inverter 20. Even without the second inverter 20, the charging system 2 (102) has the above-described advantages. However, by including the second inverter 20, the motor 30 can be driven using two inverters (the first inverter 10 and the second inverter 20). That is, high torque can be output from the motor 30. The second inverter 20 corresponds to an example of an auxiliary inverter.

[0048] The charging system 2 (102) can drive the motor 30 using the first inverter 10 and the second inverter 20. Therefore, the charging system 2 (102) may be renamed a "drive charging system".

[0049] The expression "the switching element is closed" means that the devices connected to both ends of the switching element are electrically connected. The expression "the switching element is open" means that the devices connected to both ends of the switching element are electrically separated. The expression "the switching element is turned off" is equivalent to the expression "the switching element is conducting". The expression "the switching element is open" is equivalent to the expression "the switching element is turned off".

[0050] As described above, specific examples of the present invention have been described in detail, but these are merely illustrative and do not limit the scope of the claims of the present application. The technology described in the claims of the present application includes technologies obtained by various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the 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. In addition, the technologies illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of these purposes itself has technical utility.

Claims

1. A charging system configured to transform the voltage of a power source to charge a battery, characterized in that: include: A motor having a plurality of stator coils; a power receiving terminal including a positive power receiving terminal and a negative power receiving terminal configured to be connected to the power source, the negative power receiving terminal being connected to the negative battery terminal of the battery, and the positive power receiving terminal being connected to the neutral point of the motor; A capacitor connected between the positive power receiving terminal and the negative power receiving terminal; An inverter, a DC end connected to the battery, and an AC end connected to the first end of the plurality of stator coils; a plurality of neutral point switching elements, each of which connects the second end of each of the plurality of stator coils to the neutral point; as well as A plurality of diodes are provided, wherein an anode of each of the diodes is connected to the negative power receiving terminal, and a cathode of each of the diodes is connected to the second end of each of the plurality of stator coils.

2. The charging system according to claim 1, characterized in that: Also includes a controller, the controller is configured as: When the output voltage of the power source connected to the power receiving terminal is lower than the output voltage of the battery, the plurality of neutral point switching elements are closed, and the lower switching element of the inverter is turned on and off to boost the voltage of the power source and charge the battery. When the output voltage of the power source connected to the power receiving terminal is higher than the output voltage of the battery, the neutral point switching element is turned on and off to step down the voltage of the power source and charge the battery.

3. The charging system according to claim 1 or 2, characterized in that: The controller is configured to close the plurality of neutral point switching elements and turn on and off the upper switching elements and the lower switching elements of the inverter when the motor is driven by the battery in a state where the power source is not connected to the power receiving terminal.

4. The charging system according to claim 1, characterized in that: It also includes a direct charging switch (37) for connecting the power receiving positive terminal to the positive terminal of the battery by bypassing the stator coil.

5. The charging system according to claim 1, characterized in that: It also includes a sub-inverter whose DC end is connected to the battery and whose AC end is connected to the second ends of the plurality of stator coils.

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