Charging device and power conversion device

Abstract

To achieve a voltage boost function for charging power at a low cost.SOLUTION: In a charging device 2, an inverter 20 selects, among switching elements 21a to 23b, the V-phase switching elements 22a, 22b and / or the W-phase switching elements 23a, 23b in which a connection part is not provided between coils 32, 33 as voltage boost switching elements, and can perform the voltage boost operation of boosting the voltage of the DC power from a DC power source 4 using the coils 31-33 of a rotary electric machine 30 to supply the voltage to a power storage device 11 by switching the voltage boost switching elements. A relay 42u which is connected via a connection part 41u to the switching elements 21a, 21b other than the voltage boost switching elements is switched to the ON state when the inverter 20 performs the voltage boost operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charging device and a power conversion device. [Background technology]

[0002] In recent years, as part of environmental protection and global warming countermeasures, electric vehicles such as electric cars and plug-in hybrid cars have become increasingly popular. In these electric vehicles, an on-board battery is charged with electric power provided from an external charging facility, and the electric motor is driven using the electric energy stored in the on-board battery to run the electric vehicle. Generally, there are two types of charging for on-board batteries in electric vehicles: normal charging, which converts a commercial power source for general household use into DC power and charges the battery, and rapid charging, which rapidly charges the battery using high-power DC power provided from a dedicated charging facility.

[0003] In recent years, the voltage of on-board batteries has been increasing in order to improve the driving performance of electric vehicles and the efficiency of power conversion. As a result, the voltage of DC power that can be supplied by a charging facility for quick charging (e.g., 400V) may be lower than the charging voltage of the on-board battery (e.g., 800V). As a method for making it possible to charge the on-board battery even in such cases, it is possible to install a boost circuit in the vehicle to boost the voltage of the DC power supplied from the charging facility. However, large-capacity boost circuits that can achieve this tend to be large and heavy, and are not suitable for installation in a vehicle. In addition, this also increases the cost of the vehicle.

[0004] As a technique for solving the above problem, for example, the one described in Patent Document 1 has been proposed. Patent Document 1 describes a charging system that has a first relay having one end connected to a DC connection end and the other end connected to a charging power input end, and a second relay having one end connected to a neutral point of a motor and the other end connected to a charging power input end, and that controls the states of these relays and also controls the on / off states of each switching element of an inverter, thereby enabling charging power provided from a charging facility to be boosted by a motor coil and provided to a battery. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-175363 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the charging system of Patent Document 1, the neutral point of the motor is connected to one end of the second relay, and a structure must be adopted in which the neutral point of the motor is drawn outside the motor in order to enable connection to the charging power input terminal via this second relay. In other words, in order to apply the charging system of Patent Document 1, a special structure different from the usual one must be adopted for the motor, which continues to be a factor in increasing costs.

[0007] The present invention has been made in consideration of the above problems, and a main object of the present invention is to realize a charging power boost function at low cost. [Means for solving the problem]

[0008] The charging device according to the present invention includes an inverter having a plurality of switching elements connected to a power storage device, a rotating electric machine having a plurality of windings each corresponding to a different phase of AC power output from the inverter, with one end of each winding connected to the switching element and the other end of each winding connected to each other, at least one relay having one end connected to a connection portion provided between the winding and the switching element corresponding to at least one phase of the AC power and the other end connected to a connection point with an external DC power source that supplies DC power for charging the power storage device, and being switched between an ON state or an OFF state to establish or break conduction between the connection portion and the DC power source, and a relay between the relay and the connection point. and a capacitor having one end connected to the negative electrode of the power storage device and the other end connected to the negative electrode of the power storage device, wherein the inverter selects, from among the plurality of switching elements, a switching element that does not have the connection part between the winding or is connected via the connection part to the relay that is switched to the OFF state, as a boost switching element, and is capable of performing a boost operation of boosting the voltage of the DC power using the winding and supplying it to the power storage device by switching the boost switching element, and the relay that is connected via the connection part to a switching element other than the boost switching element is switched to the ON state when the inverter performs the boost operation. The power conversion device according to the present invention includes a plurality of switching elements that perform a switching operation for converting a first DC power supplied from a power storage device into AC power and outputting the AC power to a rotating electric machine, and at least one relay having one end connected to a connection portion provided between the switching element corresponding to at least one phase of the AC power and a winding of the rotating electric machine and the other end connected to a connection point with an external DC power source that supplies second DC power for charging the power storage device, and being switched between an ON state and an OFF state to establish or break conduction between the connection portion and the DC power source, and at least one relay having one end connected between the relay and the connection point and the other end connected to a negative electrode of the power storage device. and a capacitor to which is connected, wherein a switching element among the plurality of switching elements that does not have the connection portion between the winding or is connected via the connection portion to the relay switched to the OFF state is selected as a boost switching element, and the boost switching element is switched on to perform a boost operation of boosting the voltage of the second DC power using the winding and supplying it to the power storage device, and the relay that is connected via the connection portion to a switching element other than the boost switching element is switched to the ON state when performing the boost operation. Effect of the Invention

[0009] According to the present invention, a charging power boosting function can be realized at low cost. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a configuration of a charging device according to a first embodiment of the present invention. [Diagram 2] This figure shows the time changes of the currents Iv and Iw flowing through the V-phase winding and W-phase winding, respectively, when the V-phase switching element is switched and the W-phase switching element is kept in the OFF state to perform boost operation. [Diagram 3]This figure shows the time changes of the currents Iv and Iw flowing through the V-phase winding and the W-phase winding, respectively, when the V-phase switching element is switched and the W-phase switching element is also switched to perform boost operation. [Figure 4] 13 is a diagram showing an example in which the switching period of a V-phase switching element and the switching period of a W-phase switching element are partially shifted from each other. FIG. [Diagram 5] 13 is a diagram showing an example in which the switching periods of the V-phase switching elements and the W-phase switching elements are all shifted from each other. FIG. [Figure 6] FIG. 6 is a diagram showing the configuration of a charging device according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a diagram illustrating an example of switching timing of a relay in the second embodiment of the present invention. [Figure 8] FIG. 11 is a diagram showing how line inductance changes depending on the rotor position. [Figure 9] 13 is a diagram showing an example of a fixed position of a rotor when a V-phase switching element is switched as a boost switching element. FIG. [Figure 10] 11 is a diagram showing an example of a fixed position of a rotor when a V-phase switching element and a W-phase switching element are switched as boost switching elements. FIG. [Figure 11] FIG. 13 is a diagram showing an example of line inductance when the rotor is fixed at a 50° position at the start of boost operation. [Figure 12] FIG. 13 is a diagram showing an example of line inductance when the rotor is fixed at a 120° position at the start of a voltage boosting operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) Fig. 1 is a diagram showing the configuration of a charging device according to a first embodiment of the present invention. The charging device 2 shown in Fig. 1 is mounted on and used in an electrically powered vehicle such as an electric vehicle or a plug-in hybrid vehicle, and is connected to a vehicle system 1 including an electricity storage device 11. The charging device 2 has an inverter 20 and a rotating electric machine 30.

[0012] The inverter 20 has switching elements 21a, 21b constituting an upper arm and a lower arm of the U phase, switching elements 22a, 22b constituting an upper arm and a lower arm of the V phase, and switching elements 23a, 23b constituting an upper arm and a lower arm of the W phase. These switching elements 21a to 23b are switched on and off in response to a gate signal output from a gate drive circuit (not shown), thereby converting DC power supplied from the power storage device 11 into AC power and outputting it to the rotating electric machine 30. This generates a rotational driving force in the rotating electric machine 30, and the electric vehicle can be run using this rotational driving force.

[0013] The gate drive circuit receives a gate command from a control device (not shown) configured by a microcomputer etc., and can output a gate signal to each switching element in response to the gate command. The control device can generate a gate command in response to an external torque command by performing well-known PWM control, for example, and output the gate command to the gate drive circuit, but a detailed description thereof will be omitted.

[0014] Although FIG. 1 shows an example in which each switching element of the inverter 20 is configured with a MOSFET, the switching elements 21a to 23b may be configured using other semiconductor elements such as IGBTs.

[0015] Furthermore, inverter 20 has, between switching elements 21a to 23b and power storage device 11, smoothing capacitor 26 for suppressing voltage fluctuations in the DC power supplied from power storage device 11, and Y capacitors 27a, 27b for suppressing noise.

[0016] The rotating electric machine 30 has a U-phase winding 31, a V-phase winding 32, and a W-phase winding 33, which respectively correspond to the U-phase, V-phase, and W-phase of the three-phase AC power output from the inverter 20. One end of the U-phase winding 31 is connected to the U-phase switching elements 21a and 21b of the inverter 20, one end of the V-phase winding 32 is connected to the V-phase switching elements 22a and 22b of the inverter 20, and one end of the W-phase winding 33 is connected to the W-phase switching elements 23a and 23b of the inverter 20. The other ends of the U-phase winding 31, the V-phase winding 32, and the W-phase winding 33 are connected to each other and form a neutral point of the rotating electric machine 30.

[0017] Between the inverter 20 and the rotating electric machine 30, a connection part 41u to which a wiring 40u is connected is provided between the U-phase switching elements 21a, 21b and the U-phase winding 31. A relay 42u is provided on the wiring 40u, one end of the relay 42u is connected to the connection part 41u, and the other end of the relay 42u is connected to a connection point 44. The connection point 44 is a point where the charging device 2 is electrically connected to the positive electrode of the DC power source 4 via the charging terminal 12a and the wiring 13a in the vehicle system 1 when the charging terminals 12a, 12b provided on the vehicle system 1 are connected to the external DC power source 4, and corresponds to a connector terminal or a contact (not shown) provided on the charging device 2. Note that the wiring 40u and the wiring 13a may be integrated, and an arbitrary point on this wiring may be the connection point 44.

[0018] When the charging terminals 12a, 12b are connected to the DC power source 4 and the relay 42u is switched to the ON state, the connection part 41u is electrically connected to the positive electrode of the DC power source 4 via the wiring 40u and the connection point 44. As a result, one end of the U-phase winding 31 is electrically connected to the positive electrode of the DC power source 4.

[0019] In vehicle system 1, wiring 13b is provided between charging terminal 12b and the negative electrode of power storage device 11. As a result, when charging terminal 12b is connected to DC power supply 4, the negative electrode of power storage device 11 is electrically connected to the negative electrode of DC power supply 4 via charging terminal 12b and wiring 13b.

[0020] The DC power supply 4 is, for example, a power supply for rapid charging. In this embodiment, the voltage of the DC power that the DC power supply 4 can supply (for example, about 400 Vdc) is lower than the charging voltage of the power storage device 11 (for example, about 800 Vdc).

[0021] The relay 42u is switched to an ON state or an OFF state by a control device (not shown), thereby establishing or interrupting electrical continuity between the connection portion 41u and the DC power source 4. Details of the switching control of the relay 42u will be described later.

[0022] In addition, a capacitor 43 is provided between the inverter 20 and the connection point 44. One end of the capacitor 43 is connected between the relay 42u and the connection point 44, and the other end of the capacitor 43 is connected to the negative electrode of the power storage device 11. As a result, when the charging terminal 12a is connected to the DC power source 4, the capacitor 43 is electrically inserted between the negative electrode of the power storage device 11 and the positive electrode of the DC power source 4.

[0023] 1 shows an example in which the wiring 40u, the relay 42u, and the capacitor 43 are arranged outside the inverter 20, but they may be arranged inside the inverter 20. That is, the inverter 20, which is a power conversion device, may be configured to include at least one of the wiring 40u, the relay 42u, and the capacitor 43 in addition to the switching elements 21a to 23b, the smoothing capacitor 26, and the Y capacitors 27a and 27b. Furthermore, the vehicle system 1 and the charging device 2 may include any parts or devices other than those shown in FIG. 1, such as various relays and other components.

[0024] Next, a description will be given of the operation of the charging device 2 when the DC power supply 4 is connected to the vehicle system 1 to charge the power storage device 11. At this time, the electric vehicle including the vehicle system 1 is stopped, and the position of the rotor of the rotating electric machine 30 is fixed (locked), and the positive and negative electrodes of the DC power supply 4 are connected to the charging terminals 12a and 12b, respectively.

[0025] As described above, the voltage of the DC power that can be supplied by the DC power source 4 is lower than the charging voltage of the power storage device 11. Therefore, in the charging device 2, the inverter 20 performs a boosting operation described below to boost the DC power supplied from the DC power source 4 and supply it to the power storage device 11. This makes it possible to charge the power storage device 11 using the DC power source 4.

[0026] When starting the boost operation of the inverter 20, first, all switching elements are turned off and the relay 42u is switched to the on state. As a result, the inverter 20 and the rotating electric machine 30 are electrically connected to the DC power source 4.

[0027] Next, among the switching elements 21a to 23b included in the inverter 20, the V-phase switching elements 22a and 22b that do not have a connection portion between the DC power source 4 and the corresponding V-phase winding 32 are alternately turned ON / OFF to perform a boost operation by the inverter 20. Specifically, first, the upper arm switching element 22a is turned OFF and the lower arm switching element 22b is turned ON to allow an excitation current to flow from the DC power source 4 to the U-phase winding 31 and the V-phase winding 32. Thereafter, the lower arm switching element 22b is turned OFF and the upper arm switching element 22a is turned ON to pass a boost current resulting from boosting the voltage of the DC power source 4 to the capacitor 43 and the power storage device 11. In the inverter 20, by repeating such switching operations of the V-phase switching elements 22a and 22b, a boost operation can be performed in which the DC voltage supplied from the DC power source 4 is boosted using the U-phase winding 31 and the V-phase winding 32 and supplied to the power storage device 11. In the following description, the switching elements that are switched on and off during the boost operation in the inverter 20 are also referred to as "boost switching elements."

[0028] The switching control of the boost switching elements 22a, 22b may be performed by a control device that outputs the above-mentioned gate command to a gate drive circuit when the inverter 20 converts the DC power supplied from the power storage device 11 into AC power. Alternatively, a circuit that generates a gate command for boost operation may be provided separately from the control device, and the switching control of the boost switching elements 22a, 22b may be performed by using this circuit.

[0029] Furthermore, when the V-phase switching elements 22a, 22b are used to perform the boost operation as described above, the W-phase switching elements 23a, 23b may be left in the OFF state. Alternatively, similarly to the V-phase, the W-phase switching elements 23a, 23b may also repeat a switching operation to energize the U-phase winding 31 and the W-phase winding 33 to perform the boost operation.

[0030] 2 is a diagram showing the time changes in currents Iv, Iw flowing through V-phase winding 32 and W-phase winding 33, respectively, when a boost operation is performed with V-phase switching elements 22a, 22b switched and W-phase switching elements 23a, 23b kept in the OFF state. In this case, as shown in FIG 2, current Iv through V-phase winding 32 fluctuates up and down as switching elements 22a, 22b repeat switching operations, while current Iw through W-phase winding 33 remains unchanged at 0.

[0031] 3 is a diagram showing time variations in currents Iv and Iw flowing through the V-phase winding 32 and the W-phase winding 33, respectively, when the V-phase switching elements 22a and 22b and the W-phase switching elements 23a and 23b are switched to perform a boost operation. In this case, as shown in FIG. 3, the V-phase switching elements 22a and 22b and the W-phase switching elements 23a and 23b each repeatedly switch, causing the current Iv of the V-phase winding 32 and the current Iw of the W-phase winding 33 to fluctuate up and down. At this time, the switching frequencies of the V-phase switching elements 22a and 22b and the W-phase switching elements 23a and 23b may or may not be the same.

[0032] In addition, by shifting the phases at which V-phase switching elements 22a, 22b and W-phase switching elements 23a, 23b are switched, it is possible to level out the ripple current generated in U-phase winding 31 and the ripple voltage generated in capacitor 43, and to expect the effect of effectively suppressing these. Therefore, the phases of the switching operations of the V-phase and W-phase may be shifted as necessary.

[0033] Furthermore, during the boost charging operation period, the period during which the V-phase switching elements 22a and 22b are switched and the period during which the W-phase switching elements 23a and 23b are switched may be shifted partially or entirely from each other. An example of this will be described below with reference to Figs. 4 and 5.

[0034] 4 shows an example in which the switching period T22 of the V-phase switching elements 22a and 22b and the switching period T23 of the W-phase switching elements 23a and 23b are partially shifted from each other. In this example, the V-phase switching period T22 and the W-phase switching period T23 are shifted from each other in each period shown by hatching in the figure.

[0035] 5 shows an example in which the switching period T22 of the V-phase switching elements 22a and 22b and the switching period T23 of the W-phase switching elements 23a and 23b are all shifted from each other. In this example, the V-phase switching period T22 and the W-phase switching period T23 are shifted from each other over the entire period.

[0036] 4 and 5, by making the V-phase switching period T22 and the W-phase switching period T23 not overlap each other at least partially, the heat generated during switching in the V-phase switching elements 22a and 22b and the heat generated during switching in the W-phase switching elements 23a and 23b can be dispersed in time from each other, thereby effectively preventing the inverter 20 from becoming overheated.

[0037] When charging of the power storage device 11 is completed, all the switching elements are turned off again, and the relay 42u is switched to the off state. Thereafter, the DC power supply 4 and the vehicle system 1 are disconnected.

[0038] In the charging device 2, by switching the relay 42u and performing the boosting operation of the inverter 20 as described above, the DC voltage supplied from the DC power source 4 is boosted and supplied to the electricity storage device 11, thereby charging the electricity storage device 11.

[0039] During the boost operation of the inverter 20, the temperatures of the windings 31-33 of the rotating electric machine 30 and the boost switching elements of the inverter 20 may be detected, and the output of the boost current may be adjusted based on the temperature detection result to prevent overtemperature. In particular, when both the V-phase switching elements 22a, 22b and the W-phase switching elements 23a, 23b are operated as boost switching elements, a current Iu, which is the sum of a current Iv of the V-phase winding 32 and a current Iw of the W-phase winding 33, is passed through the U-phase winding 31, causing a large temperature rise in the U-phase winding 31. Therefore, in such a case, it is preferable to reliably prevent overtemperature from occurring by monitoring the temperature of the U-phase winding 31.

[0040] Furthermore, in the above embodiment, an example has been described in which the connection portion 41u with the DC power supply 4 is provided between the U-phase switching elements 21a, 21b and the U-phase winding 31, but a connection portion with the DC power supply 4 may be provided between the V-phase switching elements 22a, 22b and the V-phase winding 32, or between the W-phase switching elements 23a, 23b and the W-phase winding 33. Even in this case, as in the above, it is possible to charge the power storage device 11 by alternately turning on and off the switching elements of the upper arm and the lower arm of a phase not provided with a connection portion as boost switching elements, thereby performing a boost operation by the inverter 20.

[0041] Furthermore, in the above embodiment, an example has been shown in which boost charging is performed from the low-voltage DC power source 4 to the high-voltage storage device 11, but the opposite may be true in which step-down power is supplied from the high-voltage storage device 11 to the low-voltage DC power source 4.

[0042] According to the first embodiment of the present invention described above, the following advantageous effects are achieved.

[0043] (1) The charging device 2 includes an inverter 20 having switching elements 21a-23b connected to the power storage device 11, a rotating electric machine 30 having windings 31-33 corresponding to different phases (U phase, V phase, W phase) of AC power output from the inverter 20, with one end of each winding connected to the switching elements 21a-23b, respectively, and the other ends of the windings connected to each other, and at least one relay (relay 42u) having one end connected to a connection part 41u provided between the switching elements 21a, 21b corresponding to at least one phase (U phase) of the AC power and the U-phase winding 31, and having the other end connected to a connection point 44 with an external DC power source 4 that supplies DC power for charging the power storage device 11, and being switched between an ON state or an OFF state to establish or break conduction between the connection part 41u and the DC power source 4, and a capacitor 43 having one end connected between the relay 42u and the connection point 44, and the other end connected to the negative electrode of the power storage device 11. The inverter 20 selects, as a boost switching element, the V-phase switching elements 22a, 22b and / or the W-phase switching elements 23a, 23b that are not provided with a connection portion between the windings 32, 33, among the switching elements 21a-23b, and switches the boost switching elements, thereby performing a boost operation of boosting the voltage of the DC power of the DC power source 4 using the windings 31-33 and supplying the boosted voltage to the electricity storage device 11. In addition, the relay 42u connected to the switching elements 21a, 21b other than the boost switching elements via a connection portion 41u is switched to an ON state when the inverter 20 performs a boost operation. Since this is done, it is not necessary to draw the neutral point of the rotating electric machine 30 to the outside, and therefore the boost function of the charging power can be realized at low cost.

[0044] Moreover, with the above configuration, the charging device 2 and the DC power supply 4 can be connected at one connection point 44, thereby achieving further cost reduction compared to a conventional circuit configuration that requires connection points on the positive and negative sides of the DC power supply 4. Furthermore, during the boost operation of the inverter 20, an excitation current can be passed through at least two phases of windings (U-phase winding 31, and V-phase winding 32 and / or W-phase winding 33) in the rotating electric machine 30, thereby making it possible to increase inductance and reduce current ripple compared to a conventional circuit configuration in which an excitation current flows through only one phase of windings.

[0045] (2) The inverter 20 can perform a boost operation by switching the boost switching elements of one of the V and W phases, using the switching elements 22a, 22b, 23a, and 23b corresponding to the two phases (V phase and W phase) of the AC power as boost switching elements. At this time, it is preferable to switch each boost switching element in the boost operation so that at least a part of the period during which the boost switching element of one phase is switched does not overlap with the period during which the boost switching element of the other phase is switched (FIGS. 4 and 5). In this way, heat generated during switching in each phase can be dispersed over time, and the inverter 20 can be effectively prevented from becoming overheated.

[0046] Second embodiment Next, a second embodiment of the present invention will be described.

[0047] Fig. 6 is a diagram showing the configuration of a charging device according to a second embodiment of the present invention. A charging device 2A shown in Fig. 6 is different from the charging device 2 described in the first embodiment in that each of the U-phase, V-phase, and W-phase is configured to be connectable to a DC power source 4. That is, the charging device 2A of this embodiment has a V-phase wiring 40v, a connection portion 41v, and a relay 42v, and a W-phase wiring 40w, a connection portion 41w, and a relay 42w, in addition to the U-phase wiring 40u, a connection portion 41u, and a relay 42u described in the first embodiment.

[0048] The connection part 41v is provided between the V-phase switching elements 22a, 22b and the V-phase winding 32, and a wiring 40v is connected to the connection part 41v. A relay 42v is provided on the wiring 40v, and one end of the relay 42v is connected to the connection part 41v and the other end of the relay 42v is connected to a connection point 44.

[0049] Connection 41w is provided between W-phase switching elements 23a, 23b and W-phase winding 33, and wiring 40w is connected to connection 41w. Relay 42w is provided on wiring 40w, and one end of relay 42w is connected to connection 41w and the other end of relay 42w is connected to connection point 44.

[0050] In this embodiment, the relays 42u, 42v, and 42w are alternately switched to the ON state while the charging device 2A is performing boost charging of the power storage device 11. This distributes the energization periods of the U-phase winding 31, the V-phase winding 32, and the W-phase winding 33 in time, averaging out heat generation due to energization.

[0051] 7 is a diagram showing an example of switching timing of the relays 42u, 42v, and 42w in the second embodiment of the present invention. When the charging device 2A starts boost charging, first, one of the relays 42u, 42v, and 42w, for example, the U-phase relay 42u, is switched to the ON state for a predetermined period. During this period, in the inverter 20, the V-phase switching elements 22a and 22b and / or the W-phase switching elements 23a and 23b are selected as boost switching elements while the U-phase switching elements 21a and 21b are in the OFF state. Then, by switching the boost switching elements, a boost operation similar to that of the first embodiment is performed, and the DC power supplied from the DC power source 4 is boosted to charge the power storage device 11.

[0052] When a predetermined period has elapsed since the U-phase relay 42u was switched to the ON state, the relay 42u is switched to the OFF state, and one of the other relays 42v, 42w, for example the V-phase relay 42v, is switched to the ON state for a predetermined period. During this period, in the inverter 20, the U-phase switching elements 21a, 21b and / or the W-phase switching elements 23a, 23b are selected as boost switching elements while the V-phase switching elements 22a, 22b are kept in the OFF state. Then, a boost operation is performed by switching the boost switching elements, and the DC power supplied from the DC power source 4 is boosted to charge the power storage device 11.

[0053] Furthermore, when a predetermined period has elapsed since the V-phase relay 42v was switched to the ON state, the relay 42v is switched to the OFF state, and the remaining W-phase relay 42w is switched to the ON state for a predetermined period. During this period, in the inverter 20, the U-phase switching elements 21a, 21b and / or the V-phase switching elements 22a, 22b are selected as boost switching elements while the W-phase switching elements 23a, 23b are kept in the OFF state. Then, a boost operation is performed by switching the boost switching elements, and the DC power supplied from the DC power source 4 is boosted to charge the power storage device 11.

[0054] Thereafter, the above operation is repeated to alternately switch the relays 42u, 42v, and 42w to the ON state at predetermined intervals and to switch the boost switching elements that are switched on during boost operation, thereby dispersing heat generated by the U-phase winding 31, the V-phase winding 32, and the W-phase winding 33.

[0055] In the above embodiment, an example has been described in which the U, V, and W phases are configured to be connectable to the DC power source 4 via the wirings 40u, 40v, and 40w connected to the connection portions 41u, 41v, and 41w, respectively, and the relays 42u, 42v, and 42w provided on the wirings 40u, 40v, and 40w, respectively, but only any two of the U, V, and W phases may be configured to be connectable to the DC power source 4. Even in this case, the relays are alternately switched to the ON state, and in the inverter 20, each switching element except for the switching element connected to the relay switched to the ON state at each predetermined period is set as a boost switching element, and the boost switching element is switched on and off, thereby performing a boost operation.

[0056] According to the second embodiment of the present invention described above, the charging device 2A includes an inverter 20 having switching elements 21a-23b connected to the power storage device 11, a rotating electric machine 30 having windings 31-33 respectively corresponding to different phases (U phase, V phase, W phase) of the AC power output from the inverter 20, one end of each winding being connected to the switching elements 21a-23b, respectively, and the other ends of each winding being connected to each other, and a rotating electric machine 30 having switching elements 21a-23b and windings 31-33 respectively corresponding to at least one phase (U phase, V phase, W phase) of the AC power. 3 and the other end is connected to a connection point 44 with an external DC power source 4 that supplies DC power for charging the power storage device 11, and the relay 42u, 42v, 42w is switched between an ON state or an OFF state to establish or cut off electrical continuity between the connection points 41u, 41v, 41w and the DC power source 4, and a capacitor 43 having one end connected between the relay 42u, 42v, 42w and the connection point 44 and the other end connected to the negative electrode of the power storage device 11. The inverter 20 selects, as a boost switching element, a switching element connected to the relays 42u, 42v, 42w switched to the OFF state via the connection parts 41u, 41v, 41w among the switching elements 21a to 23b, and switches the selected boost switching element, thereby performing a boost operation of boosting the voltage of the DC power of the DC power source 4 using the windings 31 to 33 and supplying the boosted voltage to the power storage device 11. In addition, the relays 42u, 42v, 42w connected to the switching elements 21a to 23b other than the boost switching elements via the connection parts 41u, 41v, 41w, respectively, are switched to the ON state when the inverter 20 performs the boost operation. Since this is done, as in the first embodiment, there is no need to draw the neutral point of the rotating electric machine 30 to the outside, and therefore the boost function of the charging power can be realized at low cost.

[0057] The charging device 2A also has a plurality of relays (relays 42u, 42v, 42w). One end of each of these relays 42u, 42v, 42w is connected to a connection portion 41u, 41v, 41w provided on a different phase of the AC power, and at least one of the relays 42u, 42v, 42w is switched to an ON state when the inverter 20 performs a boost operation. The inverter 20 performs a boost operation by switching each of the switching elements 21a to 23b, except for the relays 42u, 42v, 42w that are switched to an ON state and the switching elements connected via the connection portions 41u, 41v, or 41w, and switching the boost switching elements. Since this is done, the heat generated by the current passing through each winding of the rotating electric machine 30 can be dispersed over time, and the overtemperature can be further effectively suppressed.

[0058] (Third embodiment) Next, a third embodiment of the present invention will be described. In this embodiment, an example will be described in which the rotor position during voltage boosting operation is determined in consideration of the fact that the line-to-line inductance of each of the windings 31 to 33 of the rotating electric machine 30 has dependency on the rotor position.

[0059] The charging device according to this embodiment can be configured similarly to the first or second embodiment described above. In the following, the charging device according to this embodiment will be described using the configuration of the charging device 2 described in the first embodiment.

[0060] In the rotating electric machine 30, the magnetic path changes depending on the position of the rotor. Therefore, the line inductance of each of two combinations of the U-phase winding 31, the V-phase winding 32, and the W-phase winding 33 changes depending on the position of the rotor, as shown by curves 81, 82, and 83 in FIG. 8. Here, the curve 81 represents the line inductance of the U-phase and V-phase, that is, the inductance of the U-phase winding 31 and the V-phase winding 32. The curve 82 represents the line inductance of the V-phase and W-phase, that is, the inductance of the V-phase winding 32 and the W-phase winding 33, and the curve 83 represents the line inductance of the U-phase and W-phase, that is, the inductance of the U-phase winding 31 and the W-phase winding 33. In this way, the line inductance of each of the windings 31 to 33 has a rotor position dependency, and the phases of the line inductances are shifted from each other.

[0061] In this embodiment, the rotor position dependency of the line inductance of each of the windings 31 to 33 is utilized to fix the rotor to a position where the inductance of the winding energized by the switching operation is as large as possible when the switching element of any phase is switched as a boost switching element. This suppresses the ripple current flowing through each winding of the rotating electric machine 30 during the boost operation, thereby reducing magnetostrictive noise and voltage ripple generated in the rotating electric machine 30. Alternatively, the switching frequency required for the boost operation can be reduced, so that the loss of the switching element can be reduced. Generally, semiconductor elements compatible with driving at a switching frequency of about 10 kHz are often used for the switching elements 21a to 23b of the inverter 20. Therefore, it is important to ensure the magnitude of the inductance in each winding of the rotating electric machine 30 so that sufficient boost operation can be performed at this switching frequency.

[0062] Specifically, for example, as described in the first embodiment, when the relay 42u is switched to the ON state and the V-phase switching elements 22a, 22b are switched as boost switching elements to perform boost operation, the U-phase winding 31 and the V-phase winding 32 are energized and an excitation current flows. Therefore, in this case, the rotor is fixed at a position where the U-phase-V-phase line inductance shown by curve 81 is larger than the other line inductances, as shown by the dashed line 84 in Fig. 9.

[0063] Also, for example, as described in the first embodiment, when boost operation is performed by switching the V-phase switching elements 22a, 22b and the W-phase switching elements 23a, 23b as boost switching elements, the U-phase winding 31 and the V-phase winding 32, and the U-phase winding 31 and the W-phase winding 33 are each energized to flow an excitation current. Therefore, in this case, as shown by the dashed line 85 in Fig. 10, the rotor is fixed at a position where the U-phase-V-phase line inductance shown by curve 81 and the U-phase-W-phase line inductance shown by curve 83 become relatively large.

[0064] In this embodiment, the rotor position to be fixed during boost operation is preferably a position where the line inductance corresponding to the combination of energized windings is as large as possible, as described above, but it does not necessarily have to be a position where the maximum line inductance is obtained. The effect of this embodiment can be obtained at any position other than the position where the inductance of the windings energized in response to switching of the boost switching element is minimum.

[0065] Furthermore, the rotor position of the rotating electric machine 30 can be fixed by any method. For example, the rotor position can be fixed by using an electric parking lock system that operates in an electric vehicle on which the rotating electric machine 30 is mounted, that is, a fixing mechanism that can mechanically fix the rotating shaft of the rotating electric machine 30 to the housing of the reducer.

[0066] Alternatively, the rotor position may not be fixed, and the inverter 20 may start boosting operation at any rotor position. In this case, when current is applied to any of the windings of the phases, the rotor position at which the magnetic flux of that winding is at its maximum becomes a stable point, and the rotor moves to an optimal position by itself. After the rotor moves to the stable point position, the rotor may or may not be fixed at that position.

[0067] According to the third embodiment of the present invention described above, the charging device 2, 2A has a fixing mechanism capable of fixing the position of the rotor of the rotating electric machine 30. When the inverter 20 performs a boost operation, this fixing mechanism fixes the rotor to a position other than a position where the inductance of the windings 31-33 of the rotating electric machine 30 to which current is applied in response to switching of the boost switching elements is minimum. This makes it possible to suppress the ripple current flowing through the rotating electric machine 30 when the inverter 20 performs the boost operation.

[0068] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. In this embodiment, an example will be described in which switching elements to be switched on and off during boost operation are selected in consideration of the rotor position dependency of the line inductance described in the third embodiment.

[0069] The charging device according to this embodiment can also have the same configuration as the first or second embodiment described above. In the following, the charging device according to this embodiment will be described using the configuration of the charging device 2 described in the first embodiment.

[0070] As described in the third embodiment, in the rotating electric machine 30, the line inductances of the windings 31 to 33 each have rotor position dependency, and the phases are shifted from each other. In this embodiment, by utilizing the rotor position dependency of the line inductance, a boost switching element is selected so that a winding of a phase with a relatively large inductance at the rotor position during boost operation is energized. This makes it possible to obtain the same effects as the third embodiment.

[0071] Specifically, for example, when the rotor is fixed at the 50° position at the start of the boost operation, the U-phase-V-phase line inductance indicated by curve 81 becomes larger than the other line inductances, as shown by dashed line 86 in Fig. 11. Therefore, in this case, the boost operation is performed by switching V-phase switching elements 22a and 22b in inverter 20 as boost switching elements so that the U-phase winding 31 and the V-phase winding 32 are energized and an excitation current flows.

[0072] Furthermore, for example, if the rotor is fixed at the 120° position at the start of the boost operation, the U-phase-W-phase line inductance shown by curve 83 becomes larger than the other line inductances, as shown by dashed line 87 in Fig. 12. Therefore, in this case, the boost operation is performed by switching W-phase switching elements 23a, 23b in inverter 20 as boost switching elements so that U-phase winding 31 and W-phase winding 33 are energized and an excitation current flows.

[0073] 1, only relay 42u corresponding to the U phase is provided, and relays corresponding to the V phase and the W phase are not provided, so that it is not possible to energize V-phase winding 32 and W-phase winding 33 to pass an excitation current. Therefore, in this case, even if the rotor is fixed at a position where the line inductance between the V phase and the W phase is larger than the other line inductances, it is preferable to perform a boost operation by switching V-phase switching elements 22a, 22b or W-phase switching elements 23a, 23b in inverter 20 as boost switching elements so that either U-phase winding 31 and V-phase winding 32 or U-phase winding 31 and W-phase winding 33 are energized to pass an excitation current.

[0074] 6, by switching any one of the relays 42u, 42v, 42w to the ON state, it is possible to energize any two combinations of the U-phase winding 31, the V-phase winding 32, and the W-phase winding 33 to flow an excitation current. Therefore, in this case, it is preferable to switch any one of the relays 42u, 42v, 42w to the ON state and to switch any one of the U-phase switching elements 21a, 21b, the V-phase switching elements 22a, 22b, or the W-phase switching elements 23a, 23b in the inverter 20 as a boost switching element so that the windings of the two phases having the largest line-to-line inductance according to the rotor position are energized to flow an excitation current.

[0075] According to the fourth embodiment of the present invention described above, the inverter 20 selects one of the U, V, and W phases of the AC power in which the line inductance is relatively large according to the position of the rotor of the rotating electric machine 30, and performs a boost operation with the switching element corresponding to that phase as the boost switching element. This makes it possible to suppress the ripple current flowing through the rotating electric machine 30 during the boost operation of the inverter 20.

[0076] The present invention is not limited to the above-mentioned embodiment, and various modified examples are included. For example, the above-mentioned embodiments have been described in detail to easily explain the present invention, and are not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of a certain embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of a certain embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. In addition, each of the above-mentioned configurations, functions, processing units, processing means, etc. may be realized by hardware, for example, by designing them as integrated circuits. In addition, each of the above-mentioned configurations, functions, etc. may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as a program, table, file, etc. that realizes each function can be placed in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0077] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0078] 1: vehicle system, 2, 2A: charging device, 4: DC power supply, 11: power storage device, 20: inverter, 21a, 21b, 22a, 22b, 23a, 23b: switching elements, 30: rotating electric machine, 31: U-phase winding, 32: V-phase winding, 33: W-phase winding, 40u, 40v, 40w: wiring, 41u, 41v, 41w: connection portion, 42u, 42v, 42w: relay, 43: capacitor, 44: connection point

Claims

1. an inverter having a plurality of switching elements connected to the power storage device; a rotating electric machine including a plurality of windings each corresponding to a different phase of the AC power output from the inverter, one end of each winding being connected to the switching element and the other ends of each winding being connected to each other; at least one relay, one end of which is connected to a connection portion provided between the winding and the switching element corresponding to at least one phase of the AC power, and the other end of which is connected to a connection point with an external DC power source that supplies DC power for charging the power storage device, and which is switched between an ON state and an OFF state to establish or break conduction between the connection portion and the DC power source; a capacitor having one end connected between the relay and the connection point and the other end connected to a negative electrode of the power storage device, the inverter is capable of performing a boost operation of boosting a voltage of the DC power using the winding and supplying the DC power to the power storage device by selecting, as a boost switching element, a switching element from among the plurality of switching elements that does not have the connection portion between itself and the winding or that is connected via the connection portion to the relay that is switched to the OFF state, and switching the boost switching element; the relay connected to a switching element other than the boost switching element via the connection portion is switched to the ON state when the inverter performs the boost operation. Charging device.

2. the inverter performs the boost operation by switching the boost switching elements of one phase and the other phase of the two phases, the switching elements corresponding to the two phases of the AC power as the boost switching elements, respectively; The charging device according to claim 1 .

3. the inverter switches each boost switching element in the boost operation such that a period in which the boost switching element of the one phase is switched and a period in which the boost switching element of the other phase is switched do not at least partially overlap each other. The charging device according to claim 2.

4. A plurality of the relays are provided, the one end of each of the relays is connected to the connection portion provided on a different phase of the AC power, At least one of the plurality of relays is switched to the ON state when the inverter performs the boost operation, the inverter performs the boost operation by switching each of the switching elements, except for the switching element connected to the relay switched to the ON state via the connection portion, as the boost switching element. The charging device according to claim 1 .

5. A plurality of the relays are switched to the ON state or the OFF state, The charging device according to claim 4.

6. a fixing mechanism capable of fixing a position of a rotor of the rotating electric machine, the fixing mechanism fixes the rotor to a position other than a position at which an inductance of a winding among the plurality of windings that is energized in response to switching of the boost switching element is minimized when the inverter performs the boost operation. The charging device according to any one of claims 1 to 5.

7. the inverter selects a phase having a relatively large line-to-line inductance in accordance with a position of a rotor of the rotating electric machine from among the multiple phases of the AC power, and performs the boost operation by using the switching element corresponding to the selected phase as the boost switching element. The charging device according to any one of claims 1 to 5.

8. a plurality of switching elements that perform a switching operation for converting a first DC power supplied from the power storage device into AC power and outputting the AC power to a rotating electric machine; at least one relay, one end of which is connected to a connection portion provided between the switching element corresponding to at least one phase of the AC power and a winding of the rotating electric machine, and the other end of which is connected to a connection point with an external DC power source that supplies second DC power for charging the power storage device, and which is switched between an ON state and an OFF state to establish or break conduction between the connection portion and the DC power source; a capacitor having one end connected between the relay and the connection point and the other end connected to a negative electrode of the power storage device, Among the plurality of switching elements, a switching element that does not have the connection portion between itself and the winding or that is connected via the connection portion to the relay that is switched to the OFF state is selected as a boost switching element, and the boost switching element is switched to perform a boost operation of boosting the voltage of the second DC power using the winding and supplying it to the power storage device, the relay connected to a switching element other than the boost switching element via the connection portion is switched to the ON state when the boost operation is performed. Power conversion equipment.

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