Charging device for electric vehicle

Abstract

The invention provides a charging device for an electric vehicle, which can perform boost operation by using a multilevel converter circuit during charging and can improve charging efficiency. A charging device for an electric vehicle is provided with an NPC-type multilevel converter circuit for outputting a drive current to a travel motor, the NPC-type multilevel converter circuit having, in at least one leg, an upper clamp that is an upper switching clamp capable of switching operation and a lower clamp that is a lower switching clamp capable of switching operation. One of a pair of power lines for transmitting charging power is connected to a connection point between the upper switch clamp and the upper arm, and the other is connected to a connection point between the lower switch clamp and the lower arm. The controller is capable of driving the multilevel converter circuit so that the charging power is boosted by the charge pump operation using the two capacitors.

Description

Technical Field

[0001] The invention relates to a charging device for an electric vehicle. Background Art

[0002] Patent Document 1 discloses that a multilevel converter circuit using a bidirectional switch method is used to boost an input voltage by a charge pump operation of the multilevel converter circuit, thereby charging a battery at a voltage higher than the input voltage.

[0003] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2022-108885 Summary of the invention

[0004] Technical issues In an electric vehicle equipped with a high-voltage battery, a charging voltage lower than the battery voltage is sometimes supplied. In this case, if the charging voltage can be boosted and supplied to the battery without using a dedicated boosting circuit, the dedicated boosting circuit can be omitted, which is preferable.

[0005] By utilizing the bidirectional switch method of the multilevel converter circuit of Patent Document 1, the charging voltage can be boosted and supplied to the battery. However, the device is configured in such a way that the charging power is input from the middle point of the bidirectional switch. In this configuration, a diode is required to be added to the power line that transmits the charging power to the multilevel converter circuit to suppress the leakage of current from the multilevel converter circuit to the power line. In this case, the charging current is transmitted through the additional diode, resulting in increased loss.

[0006] An object of the present invention is to provide a charging device for an electric vehicle that can charge a battery and improve charging efficiency even when a low charging voltage is supplied by utilizing a voltage boosting operation of a multilevel converter circuit.

[0007] Technical Solution A charging device for an electric vehicle according to one embodiment of the present invention is mounted on an electric vehicle, the electric vehicle comprising: a driving wheel; a running motor that drives the driving wheel; and a battery that stores electric power to be supplied to the running motor. The electric vehicle charging device comprises: a multi-level converter circuit that receives power from the battery and outputs a drive current to the driving motor; a pair of power lines that transmit power for charging; and a controller that controls the multi-level converter circuit, The multilevel converter circuit is an NPC type multilevel converter circuit, which has: a first potential point and a second potential point, which are supplied with power from the battery; a third potential point, which generates a neutral point potential; at least two capacitors, which generate the neutral point potential; a plurality of output lines, which output the drive current; and a plurality of bridge arms, which correspond to the plurality of output lines, respectively. The plurality of bridge arms respectively include: an upper arm; a lower arm; an upper clamp capable of cutting off a current flowing from the upper arm to the third potential point; and a lower clamp capable of cutting off a current flowing from the third potential point to the lower arm. In at least one of the plurality of bridge arms, the upper clamp is an upper switch clamp capable of performing a switching action, In at least one of the plurality of bridge arms, the lower clamp is a lower switch clamp capable of performing a switching action, One of the pair of power lines is connected to a connection point between the upper switch clamp and the upper arm, The other of the pair of power lines is connected to a connection point between the lower switch clamp and the lower arm, The controller may drive the multilevel converter circuit so as to boost the charging electric power by a charge pump operation using the two capacitors.

[0008] Technical Effects According to the present invention, by using a multi-level converter circuit, the power for charging can be boosted and transmitted to the battery. Therefore, the circuits or elements for boosting can be reduced. In addition, when the power for charging is boosted, the charging current can flow on a path with less loss. Therefore, the charging efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a block diagram showing an electric vehicle equipped with a charging device according to an embodiment of the present invention.

[0010] Figure 2 It is shown Figure 1 Diagram of a multilevel converter circuit.

[0011] Figure 3 1 is a timing chart for explaining the voltage boosting operation of the multilevel converter circuit.

[0012] Figure 4 is a flowchart showing a battery charging control process executed by the controller.

[0013] Explanation of symbols 1 Electric Vehicles 2 Drive wheels 3 Travel motor 4 Batteries 5 Driving Operation 6 Multilevel Converter Circuit 7 Power Acquisition Department 71, 72 Power lines 8 Ministry of Communications 9 Voltage sensor 11 Controller 11a Storage unit L1~L3 output line 61~63 bridge arm 611, 621, 631 Upper arm 612, 622, 632 Lower arm 613 Upper switch clamp (upper clamp) 623, 633 upper clamp 614 Lower switch clamp (lower clamp) 624, 634 lower clamp 80 External devices C1, C2 capacitors P1 first potential point P2 Second potential point P3 The third potential point Q1 First switch Q2 Second switch Q3 Third switch Q4 Fourth switch Q5 Fifth switch Q6 Sixth switch D1~D4 Freewheeling diode D5, D6 diodes N1, N2 connection point DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification, a state where a switch is closed is referred to as being turned on, and a state where a switch is turned on is referred to as being turned off. In this specification, a connection point refers to points other than the point and also includes points of a wiring conductor that is continuous with the point without passing through a circuit element.

[0015] Figure 11 is a block diagram showing an electric vehicle equipped with a charging device according to an embodiment of the present invention. The electric vehicle 1 includes: a driving wheel 2; a running motor 3 that drives the driving wheel 2; a battery 4 that stores electric power for driving the running motor 3; a multilevel converter circuit 6 that converts electric power between the battery 4 and the running motor 3; a controller 11 that controls the multilevel converter circuit 6; and a driving operation unit 5 that is operated by the driver for driving. The driving operation unit 5 includes a steering operation unit (e.g., a steering wheel) 5a for steering, an acceleration operation unit (e.g., an accelerator pedal) 5b for accelerating, and a deceleration operation unit (e.g., a brake pedal) 5c for decelerating. The multilevel converter circuit 6 receives electric power from the battery 4 when the running motor 3 is powered and outputs a driving current to the running motor 3.

[0016] The electric vehicle 1 further includes: a power acquisition unit 7 that acquires power from the outside; a pair of power lines 71 and 72 that transmit the charging power acquired from the power acquisition unit 7; a communication unit 8 that communicates with an external device 80 for charging; and a voltage sensor 9 that detects the voltage between the power lines 71 and 72.

[0017] The charging device 20 of the present embodiment includes a multilevel converter circuit 6 , a power acquisition unit 7 , power lines 71 , 72 , a communication unit 8 , a voltage sensor 9 , and a controller 11 .

[0018] The controller 11 is a microcomputer having a storage unit 11a. The controller 11 operates according to the control program stored in the storage unit 11a. When the electric vehicle 1 is running, the controller 11 receives a signal of the operation amount from the driving operation unit 5, and controls the driving motor 3 to perform power operation or regeneration operation based on the signal. The power operation or line operation is achieved by driving the multilevel converter circuit 6. The electric vehicle 1 is driven by the operation of the driving motor 3.

[0019] In addition, when the controller 11 obtains power from the power acquisition unit 7, it drives the multilevel converter circuit 6 for charging to charge the battery 4. It should be noted that the controller 11 can be composed of a plurality of microcomputers that communicate and cooperate with each other. In this case, the microcomputer for driving control and the microcomputer for charging control can also be other configurations.

[0020] The communication unit 8 receives information on the power supplied from the external device 80, and transmits the information to the controller 11. The information on the charging power includes information indicating the voltage of the supplied power.

[0021] The battery 4 is a lithium ion secondary battery, but is not limited to this type and may be any type. The voltage of the battery 4 is a first voltage system (eg, 800V system).

[0022] The power acquisition unit 7 is a connector that can be connected to the power cable 81 of the external device 80, and the power acquisition unit 7 acquires power for charging in a wired manner. The external device 80 includes: a first type of external device that can supply DC charging power at a voltage of a first voltage system (e.g., an 800V system); and a second type of external device that can supply DC charging power at a voltage of a second voltage system (e.g., a 400V system) lower than the voltage of the first voltage system. It should be noted that the power acquisition unit 7 can also adopt a structure that can acquire charging power from an external device via electromagnetic action without contact, and can supply DC power via a rectifier circuit or the like.

[0023] The power lines 71 and 72 are connected to the multilevel converter circuit 6. The charging power acquired from the power acquisition unit 7 is transmitted to the battery 4 via some elements of the multilevel converter circuit 6 and the power lines. A relay capable of disconnecting the power lines 71 and 72 may be provided in the middle of the power lines 71 and 72.

[0024] <Multilevel converter circuit> Figure 2 It is shown Figure 1 The multilevel converter circuit 6 is a multilevel converter circuit of the NPC (Neutral Point Clamped) type, which is roughly a diode clamping method. The multilevel converter circuit 6 has: a first potential point P1 and a second potential point P2, which are supplied with power from the battery 4; at least two capacitors C1 and C2, which are connected in series; a third potential point P3, which generates a neutral point potential through the capacitors C1 and C2; a plurality of output lines L1 to L3, which output drive current to the driving motor 3; and a plurality of bridge arms 61 to 63, which correspond to the plurality of output lines L1 to L3, respectively. The following describes the structure having three output lines L1 to L3 and three bridge arms 61 to 63 corresponding to the three-phase driving motor 3.

[0025] The first potential point P1 and the second potential point P2 are respectively connected to power lines 41 and 42 connected to the battery 4. Although not shown in the figure, relays capable of interrupting the power lines 41 and 42 are provided on the power lines 41 and 42.

[0026] The capacitors C1 and C2 are connected in series between the first potential point P1 and the second potential point P2. The capacitors C1 and C2 generate a neutral point potential by using the connection point between each other as the third potential point P3. The neutral point potential is a potential in the middle between the potential of the first potential point P1 and the potential of the second potential point P2, and the neutral point potential is lower than the potential of the first potential point P1 and higher than the potential of the second potential point P2.

[0027] The first bridge arm 61 is a circuit capable of switching the connection between the corresponding output line L1 and the first potential point P1, the second potential point P2 and the third potential point P3. The second bridge arm 62 is a circuit capable of switching the connection between the corresponding output line L2 and the first potential point P1, the second potential point P2 and the third potential point P3. The third bridge arm 63 is a circuit capable of switching the connection between the corresponding output line L3 and the first potential point P1, the second potential point P2 and the third potential point P3.

[0028] The first to third bridge arms 61 to 63 include upper arms 611, 621, 631, lower arms 612, 622, 632, upper clamps 613, 623, 633, and lower clamps 614, 624, 634, respectively. The upper arms 611, 621, 631 are circuit portions that allow current to flow from the first potential point P1 to the output lines L1 to L3, respectively, when the travel motor 3 is in power operation. The lower arms 612, 622, 632 are circuit portions that allow current to flow from the output lines L1 to L3 to the second potential point P2, respectively, when the travel motor 3 is in power operation. The upper clamps 613, 623, 633 are circuit portions that allow current to flow from the third potential point P3 to the upper arms 611, 621, 631, respectively, and cut off current flowing from the upper arms 611, 621, 631 to the third potential point P3, respectively, when the travel motor 3 is in power operation. The lower clamps 614 , 624 , 634 are circuit portions that allow current to flow from the lower arms 612 , 622 , 632 to the third potential point P3 and cut off current flowing from the third potential point P3 to the lower arms 612 , 622 , 632 when the travel motor 3 is in power operation.

[0029] <First bridge arm 61> The upper arm 611 has a first switch Q1 and a second switch Q2 connected in series between the first potential point P1 and the output line L1 .

[0030] The lower arm 612 has a third switch Q3 and a fourth switch Q4 connected in series between the second potential point P2 and the output line L1 .

[0031] The first switch Q1 to the fourth switch Q4 are power semiconductor switch elements that can be driven on and off. The first switch Q1 to the fourth switch Q4 can be applied to IGBT (Insulated Gate Bipolar Transistor) or FET (Field Effect Transistor). Freewheeling diodes D1 to D4 can also be connected in parallel to the first switch Q1 to the fourth switch Q4, respectively. The freewheeling diodes D1 to D4 can be applied to power semiconductor diodes, or parasitic diodes of the first switch Q1 to the fourth switch Q4.

[0032] The upper clamp 613 is connected between the connection point N1 of the first switch Q1 and the second switch Q2 and the third potential point P3. The upper clamp 613 is a structure capable of performing a switching operation, and is hereinafter also referred to as "upper switch clamp 613". The upper switch clamp 613 has a fifth switch Q5 and a diode D5 connected in parallel to each other. When the fifth switch Q5 is turned off, the upper switch clamp 613 can allow current to flow from the third potential point P3 to the connection point N1, and on the other hand, cut off the reverse current. When the fifth switch Q5 is turned on, the upper switch clamp 613 can allow current to flow from the connection point N1 to the third potential point P3.

[0033] The lower clamp 614 is connected between the connection point N2 of the third switch Q3 and the fourth switch Q4 and the third potential point P3. The lower clamp 614 is a structure capable of performing a switching operation, and is hereinafter also referred to as "the lower switch clamp 614". The lower switch clamp 614 includes a sixth switch Q6 and a diode D6 connected in parallel to each other. When the sixth switch Q6 is turned off, the lower switch clamp 614 can allow current to flow from the connection point N2 to the third potential point P3, and on the other hand, cut off the reverse current. When the sixth switch Q6 is turned on, the lower switch clamp 614 can allow current to flow from the third potential point P3 to the connection point N2.

[0034] The fifth switch Q5 and the sixth switch Q6 can be implemented as power semiconductors such as IGBT or FET. The diodes D5 and D6 can be implemented as power semiconductor diodes or parasitic diodes of the fifth switch Q5 and the sixth switch Q6.

[0035] <Second bridge arm 62 and third bridge arm 63> The upper arms 621 and 631 are the same as the upper arm 611 of the first bridge arm 61. The lower arms 622 and 632 are the same as the lower arm 612 of the first bridge arm 61. The upper clamps 623 and 633 have a clamping diode D5 like the first bridge arm 61, but do not have a fifth switch Q5 unlike the first bridge arm 61. The lower clamps 624 and 634 have a clamping diode D6 like the first bridge arm 61, but do not have a sixth switch Q6 unlike the first bridge arm 61.

[0036] <Operation of Multilevel Converter Circuit 6> According to the multilevel converter circuit 6 configured as described above, the first bridge arm 61 functions as follows. That is, when the first and second switches Q1 and Q2 are turned on and the third and fourth switches Q3 and Q4 are turned off, the first potential point P1 is connected to the output line L1 in such a manner that a current can be output from the first potential point P1 to the output line L1. When the second switch Q2 is turned on and the first, third and fourth switches Q1, Q3 and Q4 are turned off, the third potential point P3 is connected to the output line L1 in such a manner that a current can be output from the third potential point P3 to the output line L1. When the third switch Q3 is turned on and the first, second and fourth switches Q1, Q2 and Q4 are turned off, the third potential point P3 is connected to the output line L1 in such a manner that a current can flow back from the output line L1 to the third potential point P3. When the first and second switches Q1 and Q2 are turned off and the third and fourth switches Q3 and Q4 are turned on, the second potential point P2 is connected to the output line L1 in such a manner that a current can flow back from the output line L1 to the second potential point P2. When the first to fourth switches Q1 to Q4 are turned off, the first to third potential points P1 to P3 are disconnected from the output line L1. The same applies to the bridge arms 62 and 63.

[0037] Then, the controller 11 switches the states of the plurality of bridge arms 61 to 63 to any one of the five states described above by making the phases different, thereby outputting voltages of a plurality of levels between each pair of potential points of the first potential point P1, the second potential point P2, and the third potential point P3 on the output lines L1 to L3. Then, the output can be used to drive the travel motor 3. When the travel motor 3 is in power operation, the controller 11 maintains the fifth switch Q5 and the sixth switch Q6 in an open state.

[0038] It should be noted that the controller 11 may control the fifth switch Q5 to be turned on and the current to flow through the fifth switch Q5 during the period when the current flows through the diode D5 of the first bridge arm 61. In addition, when such control is performed, the diode D5 of the first bridge arm 61 may be omitted. Similarly, the controller 11 may control the sixth switch Q6 to be turned on and the current to flow through the sixth switch Q6 during the period when the current flows through the diode D6 of the first bridge arm 61. In addition, when such control is performed, the diode D6 may be omitted.

[0039] <Connection between charging power line and multi-level converter circuit> One of the power lines 71 and 72 for transmitting charging power from the power acquisition unit 7 is connected to a connection point N1 between the upper arm 611 of the first bridge arm 61 and the upper switch clamp 613 , and the other is connected to a connection point N2 between the lower arm 612 of the first bridge arm 61 and the lower switch clamp 614 .

[0040] <Boosting Operation of Multilevel Converter Circuit> The charging device 20 of the present embodiment has a function of boosting the charging power acquired from the power acquisition unit 7 by a charge pump operation and transmitting the boosted power to the battery 4 .

[0041] Figure 3 1 is a timing diagram showing the boost operation of the multi-level converter circuit. When performing the boost operation, the controller 11 alternately switches the control of turning on the fourth switch Q4 and the fifth switch Q5 (periods T1 and T5) and the control of turning on the first switch Q1 and the sixth switch Q6 (periods T3 and T7). Between the switching, a stop period (periods T2, T4, T6, and T8) in which the first switch Q1 to the sixth switch Q6 are turned off may be inserted.

[0042] By turning on the fourth switch Q4 and the fifth switch Q5, the voltage of the power lines 71 and 72 is applied to the lower capacitor C2, and the capacitor C2 is charged. By turning on the first switch Q1 and the sixth switch Q6, the voltage of the power lines 71 and 72 is applied to the upper capacitor C1, and the capacitor C1 is charged. It should be noted that when the first switch Q1 and the fourth switch Q4 are IGBTs that do not allow reverse current to flow, the current is passed through the freewheeling diodes D1 and D4, thereby realizing the charging of the above-mentioned capacitors C1 and C2.

[0043] As a result of charging the capacitors C1 and C2, a charging voltage is generated between the first potential point P1 and the second potential point P2 by the charge pump operation. This charging voltage can be boosted to approximately twice the voltage of the power lines 71 and 72.

[0044] <Charging control processing> Next, the charging control process of the battery 4 executed by the controller 11 will be described. Figure 4 : is a flowchart showing the charging control process.

[0045] The controller 11 starts the charging control process based on an arbitrary charging request. When the charging control process is started, the controller 11 obtains information on the voltage of the charging power input via the power lines 71 and 72, that is, the voltage of the external device 80 (step S1). The voltage information may be sent to the controller 11 from the external device 80 that supplies the charging power via the communication unit 8, or may be information detected by the voltage sensor 9.

[0046] Next, the controller 11 determines whether the voltage is lower than the charging voltage of the battery 4 (step S2). As a result, if the voltage is lower than the charging voltage of the battery 4, for example, the charging voltage of the battery 4 is 800V system and the voltage of the charging power is 400V system, the controller 11 performs charging processing with a voltage boosting operation (step S3).

[0047] In step S3, the controller 11 starts to obtain power from the power acquisition unit 7, and further performs the following steps: Figure 3 Specifically, the controller 11 adjusts the duration of the stop periods T2, T4, T6, and T8 so that the charging current or charging voltage output to the battery 4 becomes a predetermined current value or voltage value. Figure 3 Here, the controller 11 can adjust the current or voltage output to the battery 4 by adjusting the duration of the charging periods T1, T3, T5, T7 to the capacitors C1 and C2 in addition to adjusting the stop periods T2, T4, T6, and T8. Through the processing of step S3, the low voltage of the power supplied from the external device 80 can be boosted to a voltage higher than the charging voltage of the battery 4, and the battery 4 can be charged with the boosted voltage.

[0048] Simultaneously with the charging process of step S3, the controller 11 determines whether the end condition of charging the battery 4 is reached (step S4). Various conditions such as charging reaching a specified amount of electricity, reaching a specified charging time, and reaching a specified charging rate of the battery 4 can be applied to the end condition of charging. Then, if the result of the determination of step S4 is yes, the controller 11 performs the process when charging ends (step S7) and ends the charging control process. The process when charging ends includes, for example, communication processing to notify the external device 80 of the end of charging, processing to disconnect the relays of the power lines 71 and 72, and the like.

[0049] On the other hand, if it is determined in step S2 that the voltage is equal to or higher than the charging voltage, the controller 11 executes the charging process without the voltage step-up operation (step S5 ).

[0050] In step S5, the controller 11 transmits the power supplied from the power acquisition unit 7 to the battery 4 via the first switch Q1 or the flyback diode D1 of the first bridge arm 61 and the fourth switch Q4 or the flyback diode D4 of the first bridge arm 61. Then, the battery 4 is charged with the power.

[0051] Simultaneously with the charging process of step S5 , the controller 11 determines whether the end condition of charging the battery 4 is met (step S6 ). If so, the controller 11 performs the charging end process of step S7 and ends the charging control process.

[0052] According to the charging control processing described above, battery 4 can be charged in both the case where charging power is received from external equipment 80 of a voltage system suitable for battery 4 and the case where charging power is received from external equipment 80 of a voltage system lower than that of battery 4.

[0053] The program of the charging control process is stored in a non-transitory computer readable medium such as the storage unit 11a of the controller 11. The controller 11 may be configured to read the program stored in the portable non-transitory recording medium and execute the program. The portable non-transitory recording medium may also store the program of the charging control process.

[0054] As described above, according to the charging device 20 of the electric vehicle 1 of the present embodiment, by using the charge pump operation of the capacitors C1 and C2 of the multilevel converter circuit 6, the charging power obtained from the power acquisition unit 7 can be boosted and transmitted to the battery 4. Therefore, even when the voltage of the charging power is lower than the voltage of the battery 4, the battery 4 can be charged by boosting. In addition, a dedicated boost circuit can be omitted, and the manufacturing cost of the charging device 20 can be reduced and the size of the device can be reduced.

[0055] In addition, according to the charging device 20 of the electric vehicle 1 of the present embodiment, the upper clamp 613 of one bridge arm 61 is an upper switch clamp 613 capable of switching, and the lower clamp 614 of one bridge arm 61 is a lower switch clamp 614 capable of switching. In addition, the power line 71 of one side of the power acquisition unit 7 is connected to the connection point between the upper switch clamp 613 of the multilevel converter circuit 6 and the upper arm 611. In addition, the power line 72 of the other side is connected to the connection point between the lower switch clamp 614 of the multilevel converter circuit 6 and the lower arm 612. Therefore, it is difficult to cause leakage of current from the multilevel converter circuit 6 through the power lines 71 and 72, and a simple connection structure between the power lines 71 and 72 and the multilevel converter circuit 6 can be achieved. As a result, it is possible to reduce the situation where a component that generates loss such as a diode is set in the path where the charging current flows, and the charging current can be supplied to the battery 4 with a small amount of loss. Therefore, it is possible to improve the charging efficiency.

[0056] Furthermore, according to the charging device 20 of the electric vehicle 1 of the present embodiment, the controller 11 acquires information on the voltage input to the power lines 71 and 72 during the charging control process. Then, the controller 11 switches between the charging process with the charge pump operation and the charging process without the charge pump operation based on the acquired voltage information (see Figure 4 Therefore, when charging the battery 4 by acquiring low-voltage power from the external device 80 or acquiring high-voltage power from the external device 80 , power can be acquired through the same power lines 71 , 72 .

[0057] In addition, according to the charging device 20 of the electric vehicle 1 of the present embodiment, the upper arms 611, 621, and 631 are respectively configured with a first switch Q1 and a second switch Q2 connected in series. In addition, the lower arms 612, 622, and 632 are respectively configured with a third switch Q3 and a fourth switch Q4 connected in series. Then, the upper clamps 613, 623, and 633 are respectively connected between the connection point N1 of the first switch Q1 and the second switch Q2 in the same bridge arm and the third potential point P3. In addition, the lower clamps 614, 624, and 634 are respectively connected between the connection point N2 of the third switch Q3 and the fourth switch Q4 in the same bridge arm and the third potential point P3. According to such a configuration, it is more difficult to generate leakage of current from the multi-level converter circuit 6 via the power lines 71 and 72, and the connection configuration of the power lines 71 and 72 with the multi-level converter circuit 6 can be made simpler. In addition, it is possible to realize the charge pump operation by switching control of a small number of components. Therefore, the reliability of the charging device 20 can be improved.

[0058] In addition, according to the charging device 20 of the electric vehicle 1 of the present embodiment, the upper clamp 613 of one of the multiple bridge arms 61 to 63 is a structure capable of performing a switching action, and the upper clamps 623 and 633 of the other bridge arms 62 and 63 are a structure of a diode D5. Similarly, the lower clamp 614 of one of the multiple bridge arms 61 to 63 is a structure capable of performing a switching action, and the lower clamps 624 and 634 of the other bridge arms 62 and 63 are a structure of a diode D6. Therefore, the same structure and the same control method as the known diode clamp type NPC multi-level converter circuit can be applied to the other bridge arms 62 and 63, which can achieve a reduction in the manufacturing cost and development cost of the device.

[0059] In addition, according to the charging device 20 of the electric vehicle 1 of the present embodiment, the upper clamp (upper switch clamp) 613 capable of switching operation is composed of the fifth switch Q5 and the clamping diode D5 connected in parallel. Similarly, the lower clamp (lower switch clamp) 614 capable of switching operation is composed of the sixth switch Q6 and the clamping diode D6 connected in parallel. Then, the controller 11 maintains the fifth switch Q5 and the sixth switch Q6 in an open state when the driving motor 3 is in power operation. Therefore, even in the bridge arm 61 where the charging current flows, the same control method as the known diode clamp type NPC multilevel converter circuit can be applied when the driving motor 3 is in power operation. That is, the multiple bridge arms 61 to 63 can be driven in the same control method. The proportion of the multilevel converter circuit 6 during the driving of the driving motor 3 is significantly greater than the proportion during the charging operation, so the degree of degradation of the element is affected by the driving period of the driving motor 3. Therefore, it is possible to suppress the large deviation of the degree of degradation of the element between the multiple bridge arms 61 to 63.

[0060] The above is a description of the embodiment of the present invention. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, a configuration is shown in which power lines 71, 72 for transmitting power for charging are connected to a bridge arm 61. However, the power line on one side may be connected to the connection point between the upper arm of one bridge arm and the upper clamp, and the power line on the other side may be connected to the connection point between the lower arm of a different bridge arm and the lower clamp. In this case, a configuration is adopted in which the upper clamp and the lower clamp to which the power line is connected can perform switching operations. In this configuration, by the same control, charging processing accompanied by a boosting action and charging processing not accompanied by a boosting action can also be performed.

[0061] In addition, in the above-mentioned embodiment, a configuration is shown in which a power line 71 on one side that transmits power for charging is connected to one bridge arm 61. However, the power line on one side may also be connected to a plurality of bridge arms or all bridge arms. In this case, in all bridge arms connected to the power line on one side, the upper clamp is set to a configuration capable of performing a switching action, and is driven simultaneously or one by one in sequence when performing a boost action. In this case, when driving the travel motor 3, a switch is provided on the power line in such a manner that a short circuit does not occur between the plurality of bridge arms connected to the power line on one side through the power line, and the switch is turned on. The same is true for the power line and the lower clamp on the other side.

[0062] In addition, in the above embodiment, the upper clamps 623 and 633 are shown to be composed of diodes D5, but the upper clamps 623 and 633 can also be composed of switching elements such as FET. Similarly, in the above embodiment, the lower clamps 624 and 634 are shown to be composed of diodes D6, but the lower clamps 624 and 634 can also be switching elements such as FET. In the case of this structure, when the controller 11 drives the driving motor 3, it is sufficient to control the switching element to be turned on while the current flows through the diodes D5 and D6. According to such a structure, the loss when the current flows through the upper clamps 613, 623, 633 and the lower clamps 614, 624, 634 can be reduced, and the efficiency of the multi-level converter circuit 6 can be improved in both cases when the driving motor 3 is driven and when the battery 4 is charged with a boost action.

[0063] In addition, in the above embodiment, the configuration in which the charging power is transmitted from the external device 80 is shown, but the charging power may be power generated inside the electric vehicle (e.g., regenerative power). In addition, the electric vehicle may be an electric vehicle equipped with an engine such as an HEV (Hybrid Electric Vehicle) or a PHEV (Plug-in Hybrid Electric Vehicle). In addition, the details shown in the embodiment can be appropriately changed within the scope of the invention.

[0064] Industrial Applicability The present invention can be applied to a charging device for an electric vehicle.

Claims

1. A charging device for an electric vehicle, characterized in that: The electric vehicle is mounted on a vehicle having a driving wheel, a running motor that drives the driving wheel, and a battery that stores electric power to be supplied to the running motor. The electric vehicle charging device comprises: a multi-level converter circuit that receives power from the battery and outputs a drive current to the driving motor; a pair of power lines that transmit power for charging; and a controller that controls the multi-level converter circuit, The multilevel converter circuit is an NPC type multilevel converter circuit, which has: a first potential point and a second potential point, which are supplied with power from the battery; and a third potential point, which generates a neutral point potential; at least two capacitors generating said neutral point potential; A plurality of output lines, which output the driving current; and a plurality of bridge arms, which correspond to the plurality of output lines respectively, The plurality of bridge arms respectively include: an upper arm; a lower arm; an upper clamp capable of cutting off a current flowing from the upper arm to the third potential point; and a lower clamp capable of cutting off a current flowing from the third potential point to the lower arm. In at least one of the plurality of bridge arms, the upper clamp is an upper switch clamp capable of performing a switching action, In at least one of the plurality of bridge arms, the lower clamp is a lower switch clamp capable of performing a switching action, One of the pair of power lines is connected to a connection point between the upper switch clamp and the upper arm, The other of the pair of power lines is connected to a connection point between the lower switch clamp and the lower arm, The controller can drive the multilevel converter circuit so as to boost the charging power by a charge pump operation using the two capacitors.

2. The electric vehicle charging device according to claim 1, characterized in that: The controller acquires information on the voltage of the charging power, and switches between a charging process in which the charge pump is operated and a charging process in which the charge pump is not operated based on the voltage information.

3. The electric vehicle charging device according to claim 1, characterized in that: The upper arm has a first switch and a second switch connected in series, The lower arm has a third switch and a fourth switch connected in series, The upper clamp is connected between the connection point of the first switch and the second switch and the third potential point, The lower clamp is connected between a connection point between the third switch and the fourth switch and the third potential point.

4. The electric vehicle charging device according to claim 3, characterized in that: The upper clamp in one of the plurality of bridge arms is the upper switch clamp, and the upper clamp in the other one or more of the other bridge arms is a diode, The lower clamp in one of the plurality of bridge arms is the lower switch clamp, and the lower clamp in the other one or more of the other bridge arms is a diode.

5. The electric vehicle charging device according to claim 4, characterized in that: The upper switch clamp has a fifth switch and a diode connected in parallel, The lower switch clamp has a sixth switch and a diode connected in parallel, The controller maintains both the fifth switch and the sixth switch in an open state when the travel motor performs power running.

Images