Control device, power storage drive system and control method

Abstract

To provide a control device which can raise voltage usage rate.SOLUTION: In a control device (2B), in an AC rotary electric machine (3) in which a first battery (4) and a second battery (6) are insulated from each other except on a route including windings, states of opening or charge of each of first upper arm switching elements (51u, 51v and 51w), first lower arm switching elements (52u, 52v and 52w), second upper arm switching elements (71u, 71v and 71w) and second lower arm switching elements (72u, 72v and 72w) are set, and thereby a control unit (9) transmits and receives power between the first battery (4) and the second battery (6) to charge one of the first battery (4) or the second battery (6).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control device, an electricity storage drive system, and a control method. [Background technology]

[0002] An AC rotating electric machine having so-called open windings in which the windings of multiple phases provided on a stator are not connected to each other (hereinafter, referred to as an open winding AC rotating electric machine) is driven by an inverter including a first drive unit that applies a voltage to one side of the windings of each phase to drive them, and a second drive unit that applies a voltage to the other side of each set of windings to drive them. In particular, the open winding AC rotating electric machine drives both sides of the windings of each phase by the first drive unit and the second drive unit.

[0003] Furthermore, some open-winding AC rotating electric machines have a common mode current that flows through the entire windings of multiple phases due to the voltage applied by the first drive section and the second drive section. Hereafter, such an inverter will be referred to as a "common power supply type." On the other hand, an inverter in which no common-mode current flows through the entire multi-phase windings, regardless of how much voltage is applied by the first and second drive units, will be referred to as an "isolated power supply type."

[0004] The common mode current flowing through the entire set of windings is the sum of the current values ​​in the entire windings, taking into account the direction of the current. For example, the direction of the current flowing from the first drive unit to the second drive unit is the positive direction, and the opposite direction is the negative direction. The sum of the currents in each winding, expressed with positive and negative signs, is the common mode current flowing through the entire windings of multiple phases. If a common mode current flows through each winding, an increase in current will cause noise generation, heat generation, and a deterioration in the voltage utilization rate. The voltage utilization rate is the ratio of the fundamental wave component of the line voltage to the DC bus voltage in the first drive unit and the second drive unit.

[0005] Since no common-mode current flows in a "power supply isolated" inverter, the above problem does not occur. However, even in a "power supply isolated" inverter, an open-winding AC rotating electric machine needs a power supply to drive the rotating part from both sides of the windings of each phase, for example, a battery is connected to the first drive unit and the second drive unit. The two batteries connected to the first drive unit and the second drive unit usually need to be charged.

[0006] When a charging device is provided for each of the two batteries connected to the first drive unit and the second drive unit, the scale of the storage drive system including the AC rotating electric machine driven by the first drive unit and the second drive unit becomes large. As a conventional technique for solving this problem, for example, Patent Document 1 describes a drive unit including a capacitor that causes one of the first drive unit and the second drive unit to function as a battery. During the operation of the AC rotating electric machine, this drive unit extracts from the capacitor the same amount of power as that used to drive the AC rotating electric machine, and charges the battery connected to the other drive unit through the winding with the power from the capacitor. In this way, a component that performs switching to balance the power balance of the capacitor during operation (see Fig. 4 of Patent Document 1) makes it possible to select one of the two drive units to be connected to the charging device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 8,648,562 Summary of the Invention [Problem to be solved by the invention]

[0008] The conventional technology described in Patent Document 1 requires setting a switching pattern period according to the current state of the windings of the AC rotating electric machine in order to balance the power balance of the capacitor during operation, and has the problem that the voltage utilization rate decreases depending on the switching pattern setting.

[0009] The present disclosure is devised to solve the above-mentioned problems, and has an object to provide a control device that can increase the voltage utilization rate. [Means for solving the problem]

[0010] A control device according to the present disclosure includes a first drive unit for driving an AC rotating electric machine having a stator with a multi-phase winding and a rotor, the multi-phase windings not being connected to each other, the first drive unit having a plurality of first upper arm switching elements and a plurality of first lower arm switching elements, all of whose one ends on the high potential side of the first upper arm switching elements are connected to the positive electrode of a first battery, the other ends of the plurality of first upper arm switching elements are connected to one end on the high potential side of a corresponding first lower arm switching element and to one end of the multi-phase windings, and the other ends of the plurality of first lower arm switching elements are all connected to the negative electrode of the first battery; and a drive unit for driving the AC rotating electric machine, the drive unit having a plurality of second upper arm switching elements and a plurality of second lower arm switching elements, the second upper arm switching elements being connected to the positive electrode of a first battery. the first upper arm switching element, the first lower arm switching element, the second lower arm switching element, and the second upper arm switching element are connected to a positive electrode of the second battery that is insulated from the first battery except for a path including the winding, the second upper arm switching elements have their other ends connected to one end of the high potential side of a corresponding second lower arm switching element and to the other end of the multi-phase winding, and the second lower arm switching elements have their other ends connected to the negative electrode of the second battery; and a control unit that transmits and receives power between the first battery and the second battery to charge either the first battery or the second battery by setting an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. Effect of the Invention

[0011] According to the present disclosure, in an AC rotating electric machine in which a first battery and a second battery are insulated from each other except through a path including windings, by setting the open or charged state of each of a first upper arm switching element, a first lower arm switching element, a second upper arm switching element and a second lower arm switching element, power is transmitted and received between the first battery and the second battery to charge either the first battery or the second battery. In this way, the control device disclosed herein is a "power source isolated type" device in which the first battery and the second battery are insulated from each other except in paths including the windings, so that no common mode current flows through the windings of the AC rotating electric machine, and the control device charges either the first battery or the second battery using power transmitted between the first battery and the second battery by setting the switching element of the drive unit to an open or conductive state. The control device according to the present disclosure does not have the components that reduce the voltage utilization rate described in Patent Document 1, and therefore can increase the voltage utilization rate. Furthermore, since the control device of the present disclosure charges either the first battery or the second battery using power transmitted and received between the first battery and the second battery, it is only necessary to connect a charging device to either the first drive unit or the second drive unit, thereby avoiding an increase in the size of the device. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a configuration example of a power storage drive system according to a first embodiment. [Diagram 2] 4 is a block diagram showing an example of the configuration of a control unit according to the first embodiment. FIG. [Diagram 3] 4 is a flowchart showing a control method according to the first embodiment. [Figure 4] 1 is a table showing the d-axis ranges and the corresponding a-phase, b-phase, and c-phase, and their positive and negative values. [Diagram 5] FIG. 2 is a region diagram showing regions (1) to (6) corresponding to the d-axis range in a three-phase AC coordinate system of uvw phases. [Figure 6] 4 is a table showing the open and conductive states of switching elements in direct charging. [Figure 7] FIG. 13 is a diagram showing a clipping of a voltage command and a limit of a voltage that can be applied in step-down charging. [Figure 8] 1 is a table showing the open state and the conductive state of switching elements during step-down charging. [Figure 9] 1 is a table showing the open state and the conductive state of switching elements in each mode during step-down charging. [Figure 10] FIG. 13 is a diagram showing a clip of a voltage command and a limit of a voltage that can be applied in boost charging. [Figure 11] 1 is a table showing the open and conductive states of switching elements during boost charging. [Figure 12] 1 is a table showing the open state and the conductive state of switching elements in each mode during boost charging. [Figure 13] 1 is a table showing the d-axis range, the corresponding a-phase, b-phase, c-phase, d-phase, and e-phase, their positive and negative polarities, and the open and conductive states of the switching elements in direct charging. [Figure 14] 14A and 14B are block diagrams showing a hardware configuration for realizing the functions of the control unit according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Embodiment 1 Fig. 1 is a block diagram showing a configuration example of an electricity storage drive system 1 according to a first embodiment. In Fig. 1, the electricity storage drive system 1 is a device that drives an AC rotating electric machine 3, and includes a control device 2, the AC rotating electric machine 3, a first battery 4, and a second battery 6. The control device 2 includes a first drive unit 5, a second drive unit 7, and a control unit 9. The control device 2 controls the drive of the AC rotating electric machine 3, and charges either the first battery 4 or the second battery 6. First, the AC rotating electric machine 3 will be described in detail.

[0014] (AC rotating motor 3) The AC rotating electric machine 3 includes a stator, which is a fixed part provided with windings of multiple phases, and a rotor, which is a rotor. In the AC rotating electric machine 3, the windings provided on the stator are so-called open windings, in which the windings of the multiple phases are not directly connected to each other. The control device 2 can control the current flowing through the windings of each phase by applying a voltage to both ends of the windings of each phase provided in the AC rotating electric machine 3. The first battery 4 and the second battery 6 are insulated from each other except for the path including the windings of the AC rotating electric machine 3.

[0015] In the following description, it is assumed that AC rotating electric machine 3 is a three-phase machine having windings 31u, 31v and 31w corresponding to the u-phase, v-phase and w-phase, respectively. However, the AC rotating electric machine 3 may be a five-phase machine provided with windings corresponding to the u-phase, v-phase, w-phase, x-phase, and y-phase, respectively.Also, the AC rotating electric machine 3 may be an n-phase machine provided with n sets of windings, where n is any integer.Note that the case of an n-phase machine will be explained as appropriate.

[0016] A synchronous motor is used for the AC rotating electric machine 3. Examples of synchronous motors include permanent magnet synchronous motors, field winding synchronous motors, and reluctance motors. A permanent magnet synchronous motor is a motor with a permanent magnet provided on the rotor. A field winding synchronous motor is a motor with an electromagnet provided on the rotor using a field winding. A reluctance motor is a motor that does not have a permanent magnet or field winding on the rotor, is made of a ferromagnetic material such as an iron core, and utilizes a magnetic reluctance difference.

[0017] The rotor is provided with an angle sensor 8 that detects the rotation angle of the rotor. A detection signal indicating the rotation angle of the rotor detected by the angle sensor 8 is input to a control unit 9. The angle sensor 8 may be any of various sensors such as a Hall element, a resolver, or an encoder. The AC rotating electric motor 3 may be a so-called sensorless type electric motor that does not have an angle sensor 8 and estimates the rotation angle, i.e., the magnetic pole position, based on current information obtained by superimposing harmonic components on the current command value.

[0018] (First drive unit 5) The first drive unit 5 is a drive device connected to the AC rotating electric machine 3 and converts DC power into AC power to drive the AC rotating electric machine 3. The first drive unit 5 has, for each phase of the AC, a series circuit of a first upper arm switching element 51u and a first lower arm switching element 52u, a series circuit of a first upper arm switching element 51v and a first lower arm switching element 52v, and a series circuit of a first upper arm switching element 51w and a first lower arm switching element 52w.

[0019] In the first drive unit 5, three series circuits of a first upper arm switching element 51u and a first lower arm switching element 52u, a first upper arm switching element 51v and a first lower arm switching element 52v, and a first upper arm switching element 51w and a first lower arm switching element 52w are provided corresponding to the windings of each phase between a positive-side DC bus 51P through which DC power flows and a negative-side DC bus 51N through which DC power flows. The positive-side DC bus 51P is connected to the positive side of the first battery 4, and the negative-side DC bus 51N is connected to the negative side of the first battery 4.

[0020] In the u-phase series circuit in which the u-phase first upper arm switching element 51u and the u-phase first lower arm switching element 52u are connected in series, a connection point of the two arm switching elements is connected to one u-phase terminal of the AC rotating electric machine 3 via a u-phase AC wire 55u. In the v-phase series circuit in which the v-phase first upper arm switching element 51v and the v-phase first lower arm switching element 52v are connected in series, a connection point of the two arm switching elements is connected to one v-phase terminal of the AC rotating electric machine 3 via a v-phase AC wire 55v. In the w-phase series circuit in which the w-phase first upper arm switching element 51w and the w-phase first lower arm switching element 52w are connected in series, a connection point of the two arm switching elements is connected to one w-phase terminal of the AC rotating electric machine 3 via a w-phase AC wire 55w.

[0021] The switching elements of the upper and lower arms use, for example, insulated gate bipolar transistors (IGBTs) with diodes connected in inverse parallel, metal oxide semiconductor field effect transistors (MOSFETs) having the function of inverse parallel connected diodes, or bipolar transistors with diodes connected in inverse parallel. A gate terminal of each switching element is connected to the control unit 9 via a gate drive circuit etc. The control unit 9 controls the open state or the conductive state of each switching element by a control signal.

[0022] The switching element is formed using a wide band gap semiconductor, such as a SiC (silicon carbide)-based material, a GaN (gallium nitride)-based material, or a diamond-based material. The switching elements may be formed using a Si (silicon) semiconductor.

[0023] The smoothing capacitor 53 is connected between the DC bus 51P and the DC bus 51N. The high potential side DC bus 51P is connected to the positive electrode side of the first battery 4, and the low potential side DC bus 51N is connected to the negative electrode side of the first battery 4. The first battery 4 is usually composed of a battery unit having a plurality of battery cells, a voltage detection unit for detecting a voltage V1 of the positive electrode relative to the negative electrode of the first battery 4, and a communication unit. This battery unit is communicatively connected to the control unit 9. For example, a signal indicating the DC voltage V1 detected by a voltage sensor provided in the first battery 4 is transmitted to the control unit 9 via CAN (Car Area Network) communication. The first battery 4 may be composed of only a single or multiple battery cells, in which case it may be provided with a voltage sensor (not shown in FIG. 1) for detecting the DC voltage Vpn1 (hereinafter referred to as the first bus DC voltage Vpn1) between the high potential side DC bus 51P and the low potential side DC bus 51N, and Vpn1 may be substituted for V1.

[0024] The current sensor 55 is a sensor that detects the current flowing through the u-phase winding 31u, the v-phase winding 31v, and the w-phase winding 31w. For example, the current sensor 55 for each phase is provided on the AC electric wires 55u, 55v, and 55w that connect the above-mentioned series circuit of each phase to the windings 31u, 31v, and 31w of each phase. The current sensor 55 is a current detection resistor or a Hall element. A detection signal indicating the current value of each phase detected by the current sensor 55 of each phase is input to the control unit 9.

[0025] A chargeable and dischargeable power storage device (for example, a lithium ion battery, a nickel metal hydride battery, or an electric double layer capacitor) is used as the first battery 4. The first battery 4 may be provided with a charging device for charging and discharging the first battery 4 with external power. The charging device may be, for example, an AC charger that converts AC power from a grid power into DC power and uses the DC power to charge the first battery 4. The charging device may also include a connector for receiving power from an external DC charger.

[0026] (Second drive unit 7) The second drive unit 7 is connected to the side of the AC rotating electric machine 3 opposite to the first drive unit 5, and is a drive device that drives the AC rotating electric machine 3 by converting DC power into AC power. The second drive unit 7 has, for each phase of the AC, a series circuit of a second upper arm switching element 71u and a second lower arm switching element 72u, a series circuit of a second upper arm switching element 71v and a second lower arm switching element 72v, and a series circuit of a second upper arm switching element 71w and a second lower arm switching element 72w.

[0027] In the second drive unit 7, three sets of series circuits of a second upper arm switching element 71u and a second lower arm switching element 72u, a series circuit of a second upper arm switching element 71v and a second lower arm switching element 72v, and a series circuit of a second upper arm switching element 71w and a second lower arm switching element 72w are provided corresponding to the windings of each phase between a positive DC bus through which DC power flows and a negative DC bus through which DC power flows. The positive DC bus is connected to the positive side of the second battery 6, and the negative DC bus is connected to the negative side of the second battery 6.

[0028] In the u-phase series circuit in which the u-phase second upper arm switching element 71u and the u-phase second lower arm switching element 72u are connected in series, a connection point of the two arm switching elements is connected to one u-phase terminal of the AC rotating electric machine 3 via a u-phase AC wire 74u. In the v-phase series circuit in which the v-phase second upper arm switching element 71v and the v-phase second lower arm switching element 72v are connected in series, a connection point of the two arm switching elements is connected to one v-phase terminal of the AC rotating electric machine 3 via a v-phase AC wire 74v. In the w-phase series circuit in which the w-phase second upper arm switching element 71w and the w-phase second lower arm switching element 72w are connected in series, a connection point of the two arm switching elements is connected to one w-phase terminal of the AC rotating electric machine 3 via a w-phase AC wire 74w.

[0029] The switching elements of the upper arm and the lower arm are formed using a wide band gap semiconductor. For example, the wide band gap semiconductor is a SiC-based material, a GaN-based material, or a diamond-based material. The switching elements may be formed using a Si semiconductor. The smoothing capacitor 73 is connected between the high-potential side DC bus and the low-potential side DC bus. The high-potential side DC bus is connected to the positive electrode side of the second battery 6, and the low-potential side DC bus is connected to the negative electrode side of the second battery 6.

[0030] Similarly to the first battery 4, the second battery 6 is usually configured with a battery unit having a plurality of battery cells, a voltage detection unit for detecting a voltage V2 of the positive electrode of the second battery 6 based on the negative electrode of the second battery 6, and a communication unit. This battery unit is communicatively connected with the control unit 9. For example, a signal indicating the DC voltage V2 detected by a voltage sensor included in the second battery 6 is transmitted to the control unit 9 via CAN communication. The second battery 6 may be composed of only a single or multiple battery cells, in which case it may be provided with a voltage sensor (not shown in FIG. 1) for detecting the DC voltage Vpn2 between the high potential side DC bus and the low potential side DC bus (hereinafter referred to as the second bus DC voltage Vpn2), and Vpn2 may be substituted for V2.

[0031] The second drive unit 7 may be provided with current sensors (not shown in FIG. 1) that detect the currents flowing through the u-phase winding 31u, the v-phase winding 31v, and the w-phase winding 31w. For example, the current sensors for each phase are provided on the AC wires 74u, 74v, and 74w that connect the above-mentioned series circuits for each phase to the windings 31u, 31v, and 31w for each phase. Detection signals indicating the current values ​​of each phase detected by the current sensors for each phase are input to the control unit 9. Note that when a charging device is connected to the first battery 4, no charging device is connected to the second battery 6. As shown by the arrows in Fig. 1, the direction of current flowing from the first drive unit 5 to the second drive unit 7 is the positive direction, and the direction of current flowing from the second drive unit 7 to the first drive unit 5 is the negative direction. The common mode current is a current equivalent to the sum of the currents of the respective windings when the currents of the respective windings are expressed with signs. However, in the energy storage drive system 1, since the control device 2 is of the "power supply isolated type", basically, the common mode current as shown in Fig. 1 does not flow.

[0032] Fig. 2 is a block diagram showing an example of the configuration of the control unit 9. In Fig. 2, the control unit 9 includes a current command generating unit 21, a charging control unit 22, and a switching signal generating unit 23. The current command generating unit 21 generates a current command indicating a current to be set in the AC rotating electric machine 3. For example, the current command generating unit 21 may generate a preset charging current target value I * and the charging voltage target value V * Based on this, the current command I b * and the current command I c * and generate the current command I b * and the current command I c * to the charging control unit 22.

[0033] The charging control unit 22 controls the current command I b * and the current command I c * By setting the open or conductive states of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w based on the switching signals generated using the switching signals, power is transmitted and received between the first battery 4 and the second battery 6 to charge the first battery 4 or the second battery 6.

[0034] For example, the charging control unit 22 may set a current command I b * , current command I c * , the detected current values ​​Iu, Iv, and Iw of each phase, the rotor rotation angle θ, the DC voltage V1 in the first drive unit 5, and the DC voltage V2 in the second drive unit 7 are used to generate signals Du1, Du2, Dv1, Dv2, Dw1, and Dw2 indicating the switching duty ratios. The signals Du1, Du2, Dv1, Dv2, Dw1, and Dw2 are output from the charging control unit 22 to the switching signal generation unit 23. Du1 is a duty ratio for switching the first upper arm switching element 51u and the first lower arm switching element 52u. Du2 is a duty ratio for switching the second upper arm switching element 71u and the second lower arm switching element 72u. Dv1 is a duty ratio for switching the first upper arm switching element 51v and the first lower arm switching element 52v. Dv2 is a duty ratio for switching the second upper arm switching element 71v and the second lower arm switching element 72v. Dw1 is a duty ratio for switching the first upper arm switching element 51w and the first lower arm switching element 52w. Dw2 is a duty ratio for switching the second upper arm switching element 71w and the second lower arm switching element 72w.

[0035] The switching signal generating unit 23 generates switching signals that switch between an open state and a conductive state of each of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w.

[0036] For example, the switching signal generating unit 23 generates switching signals UH1, UH2, UL1, UL2, VH1, VH2, VL1, VL2, WH1, WH2, WL1 and WL2 based on signals Du1, Du2, Dv1, Dv2, Dw1 and Dw2 indicating duty ratios from the charging control unit 22. The switching signal UH1 is a signal for switching the first upper arm switching element 51u. The switching signal generator 23 outputs the switching signal UH1 to the first upper arm switching element 51u. The first upper arm switching element 51u switches between an open state and a conductive state based on the switching signal UH1. The switching signal UH2 is a signal for switching the second upper arm switching element 71u. The switching signal generator 23 outputs the switching signal UH2 to the second upper arm switching element 71u. The second upper arm switching element 71u switches between an open state and a conductive state based on the switching signal UH2. The switching signal UL1 is a signal for switching the first lower arm switching element 52u. The switching signal generator 23 outputs the switching signal UL1 to the first lower arm switching element 52u. The first lower arm switching element 52u switches between an open state and a conductive state based on the switching signal UL1. The switching signal UL2 is a signal for switching the second lower arm switching element 72u. The switching signal generator 23 outputs the switching signal UL2 to the second lower arm switching element 72u. The second lower arm switching element 72u switches between an open state and a conductive state based on the switching signal UL2. The switching signal VH1 is a signal for switching the first upper arm switching element 51v. The switching signal generator 23 outputs the switching signal VH1 to the first upper arm switching element 51v. The first upper arm switching element 51v switches between an open state and a conductive state based on the switching signal VH1. The switching signal VH2 is a signal for switching the second upper arm switching element 71v. The switching signal generator 23 outputs the switching signal VH2 to the second upper arm switching element 71v. The second upper arm switching element 71v switches between an open state and a conductive state based on the switching signal VH2. The switching signal VL1 is a signal for switching the first lower arm switching element 52v. The switching signal generator 23 outputs the switching signal VL1 to the first lower arm switching element 52v. The first lower arm switching element 52v switches between an open state and a conductive state based on the switching signal VL1. The switching signal VL2 is a signal for switching the second lower arm switching element 72v. The switching signal generator 23 outputs the switching signal VL2 to the second lower arm switching element 72v. The second lower arm switching element 72v switches between an open state and a conductive state based on the switching signal VL2. The switching signal WH1 is a signal for switching the first upper arm switching element 51w. The switching signal generator 23 outputs the switching signal WH1 to the first upper arm switching element 51w. The first upper arm switching element 51w switches between an open state and a conductive state based on the switching signal WH1. The switching signal WH2 is a signal for switching the second upper arm switching element 71w. The switching signal generator 23 outputs the switching signal WH2 to the second upper arm switching element 71w. The second upper arm switching element 71w switches between an open state and a conductive state based on the switching signal WH2. The switching signal WL1 is a signal for switching the first lower arm switching element 52w. The switching signal generator 23 outputs the switching signal WL1 to the first lower arm switching element 52w. The first lower arm switching element 52w switches between an open state and a conductive state based on the switching signal WL1. The switching signal WL2 is a signal for switching the second lower arm switching element 72w. The switching signal generator 23 outputs the switching signal WL2 to the second lower arm switching element 72w. The second lower arm switching element 72w switches between an open state and a conductive state based on the switching signal WL2.

[0037] The control unit 9 changes the conduction state of any of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w, to transmit and receive power between the first battery 4 and the second battery 6 in order to charge the first battery 4 or the second battery 6. The control device 2 that performs such control is a "power supply insulation type", so that a common mode current does not flow through the windings of the AC rotating electric machine 3 and the voltage utilization rate can be increased. Furthermore, the control device 2 only needs to connect a charging device to, for example, the second drive unit 7 out of the first drive unit 5 and the second drive unit 7, so that an increase in the scale of the storage drive system 1 can be suppressed.

[0038] (Charging control sequence) Next, a method for controlling charging of the battery connected to the power storage driving system 1 according to the first embodiment will be described. 3 is a flowchart showing a control method according to embodiment 1. The flowchart shows a sequence in which the power of the first battery 4 is supplied to the second battery 6 for charging. It should be noted that, when the first battery 4 is charged by a charging device provided outside the control device 2, the power of the first battery 4 also includes the charging power.

[0039] The control unit 9 determines whether or not charging is to be started (step ST1). For example, the control unit 9 determines that the series of processes shown in Fig. 3 should be started by inputting a control signal indicating the start of charging from the outside (step ST1; YES). If the control signal is not obtained, the control unit 9 does not start charging (step ST1; NO).

[0040] When the charging process is started, the control unit 9 sets a charging target (step ST2). The charging target is a charging target current or a charging target voltage. The charging target may be a certain constant value, or may be a value given to the control unit 9 from outside. In general, constant current and constant voltage charging is considered desirable for lithium ion batteries. This means that charging is performed so that neither a predetermined current amount nor a predetermined voltage is exceeded. In setting the charging target, a predetermined current amount and a predetermined voltage are set as the target current and target voltage, respectively. The predetermined current amount is determined for each battery temperature, and the target current may be set after detecting the battery temperature.

[0041] Also, the setting may be made in consideration of not only the protection of the second battery 6 being charged, but also the protection of the first battery 4 being discharged. For example, for a given current amount, a given voltage value, and a given voltage threshold, when the voltage of the second battery 6 falls below the given voltage threshold, the given current amount is set as the target current, and when it is equal to or greater than the given voltage threshold, the target current is reduced so as to become zero at the given voltage value.

[0042] Next, the control unit 9 judges whether or not direct charging should be performed (step ST3). If it is judged that it is appropriate to perform direct charging (step ST3; YES), the control unit 9 proceeds to step ST4 and performs direct charging. If it is judged that it is not appropriate to perform direct charging (step ST3; NO), the control unit 9 proceeds to step ST6.

[0043] (Definition of various charging terms) Direct charging, step-down charging, and step-up charging require case-specific operation depending on the rotor angle, etc. (for example, six case categories in the case of a three-phase machine). Note that the main operations in these charging methods are essentially the same, and terms for briefly explaining the essentially common operations are defined below. Fig. 4 is a table showing the d-axis ranges and the corresponding a-phase, b-phase, and c-phase and their positive and negative values. Fig. 5 is a region diagram showing regions (1) to (6) corresponding to the d-axis ranges in a three-phase AC coordinate system of uvw phases.

[0044] In Fig. 4, for example, among the u-axis, v-axis, and w-axis, the axis with the smallest absolute value of the angle at which it intersects with the d-axis is designated as the a-phase, and the phases are called b-phase, c-phase, d-phase, and e-phase in rotational order from the a-phase (in a three-phase machine, the phases are a-phase, b-phase, and c-phase). When selecting the a-phase, the positive or negative direction of each phase axis is not taken into consideration, and the intersection angle is found by regarding them as straight lines. That is, for example, in a three-phase machine, since the d-axis is 45 degrees ahead of the u-phase, the a-phase is the w-phase, not the u-phase. When considering the positive and negative axial directions, the absolute value of the difference between the d-axis and w-axis directions is 165 degrees; however, when the a-phase is selected, the angle at which the d-axis and w-axis intersect is set to 15 degrees, regardless of whether the axial direction is positive or negative.

[0045] When the absolute value of the angle difference between the direction of the axis of the phase corresponding to the a-phase (hereinafter referred to as the a-axis; the same applies to the b-axis, etc.) and the direction of the d-axis is 90 degrees or less, that is, when the dot product of the direction vector indicating the positive direction of the a-axis and the direction vector indicating the positive direction of the d-axis is positive or zero, this situation is called a "positive pattern." Also, when the dot product of the direction vector indicating the positive direction of the a-axis and the direction vector indicating the positive direction of the d-axis is negative, this situation is called a "negative pattern." An example will be given for a three-phase machine.

[0046] As shown in Figure 5, there are six regions (1) to (6) in which the d-axis is shifted from the u-axis in the positive rotation direction, and there are six cases corresponding to these regions (1) to (6). That is, as shown below, there are six patterns, consisting of three patterns and two combinations called positive and negative patterns, depending on which of uvw corresponds to abc. In region (1), the a phase is the u phase, which is a positive pattern. In region (2), the a phase is the w phase, which is a negative pattern. In region (3), the a phase is the v phase, which is a positive pattern. In region (4), the a-phase is the u-phase, which is a negative pattern. In region (5), the a phase is the w phase, which is a normal pattern. In region (6), the a-phase is a v-phase, which is a negative pattern.

[0047] (Direct charging) The control unit 9 executes direct charging (step ST4). For example, it is assumed that the AC rotating electric machine 3 is a three-phase machine. In direct charging, the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected, forming a closed current path to transmit and receive power between the first battery 4 and the second battery 6. The control unit 9 sets the conductive or open state of each switching element, so that the first battery 4 and the second battery 6 are electrically connected with each other, with the winding of the AC rotating electric machine 3 serving as a conductor. In the case of the direct charging, in the case of the positive pattern, the control unit 9 sets the first upper arm switching element 51u in a conductive state and the remaining first upper arm switching elements 51v and 51w in an open state among the first upper arm switching elements 51u, 51v, and 51w provided in the first drive unit 5, which correspond to the a-phase (if the a-phase corresponds to the u-phase). The control unit 9 sets the first lower arm switching elements 52u, 52v, and 52w provided in the first drive unit 5 in a complementary state to the first upper arm switching elements 51u, 51v, and 51w corresponding thereto.

[0048] The complementary state is a state in which a lower arm switching element corresponding to an upper arm switching element in a conductive state is opened, and a lower arm switching element corresponding to an upper arm switching element in an open state is opened. For example, the first lower arm switching element 52u corresponding to the first upper arm switching element 51u in a conductive state is opened. On the other hand, the first lower arm switching elements 52v and 52w corresponding to the first upper arm switching elements 51v and 51w in an open state are opened. However, when switching, the complementary state is not strictly maintained, but a so-called dead time process is added. That is, in order to prevent a short circuit between the upper arm and the lower arm when switching, the switching elements that are to be opened are opened before the switching elements that are to be opened are made conductive between the corresponding switching elements of the upper and lower arms.

[0049] The control unit 9 sets the second upper arm switching elements 71u, 71v, and 71w included in the second drive unit 7, which correspond to the a-phase, to a conductive state, and sets the remaining switching elements to an open state. Similarly to the first drive unit 5, the control unit 9 also sets the second lower arm switching elements 72u, 72v, and 72w to a complementary state with the corresponding switching elements on the upper arm side. In addition, in the case of a negative pattern, the control unit 9 sets the switching elements that were in a conductive state in the case of a positive pattern to an open state, and sets the switching elements that were in an open state to a conductive state. That is, in the case of a negative pattern, among the first upper arm switching elements 51u, 51v, and 51w provided in the first drive unit 5, those corresponding to the a-phase are set to an open state, and the remaining switching elements are set to a conductive state. At this time, the first lower arm switching elements 52u, 52v, and 52w are set to a complementary state to the corresponding upper arm switching elements.

[0050] Similarly, in the second drive unit 7, the control unit 9 sets the second upper arm switching elements 71u, 71v, and 71w included in the second drive unit 7, which correspond to the a-phase, to an open state, and sets the remaining switching elements to a conductive state. Furthermore, the control unit 9 also sets the second lower arm switching elements 72u, 72v, and 72w to a complementary state with the switching elements corresponding to the second upper arm switching elements. In this way, in the direct charging control, the conductive states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element and the second lower arm switching element are fixedly set, so that the first battery 4 and the second battery 6 are electrically connected (directly connected) via the first drive unit 5 and the second drive unit 7, and charging is performed using power transmitted and received between the first battery 4 and the second battery 6.

[0051] 6 is a table showing the open and conductive states of the switching elements in direct charging. The control unit 9 sets the switching elements included in the first drive unit 5 and the second drive unit 7 to the open and conductive states shown in FIG. However, for any one of the two phases other than phase a, both the upper arm switching element and the lower arm switching element for the same phase in the first drive unit 5 and the second drive unit 7 may be in an open state without being conductive. As shown in FIG. 6, in direct charging, the open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element is predetermined, and the conductive states of these elements are fixedly set.

[0052] When direct charging is completed, the control unit 9 determines whether or not to end charging based on the following conditions (step ST5). If it is determined that charging has ended (step ST5; YES), the control unit 9 ends the series of processes shown in Fig. 3. On the other hand, if it is determined that charging has not ended (step ST5; NO), the control unit 9 returns to the process of step ST2. Returning to the process of step ST2, the control unit 9 sets a new charging target in step ST2 in accordance with a change in the charging state from the previous time.

[0053] (Voltage conditions) If direct charging is performed when the voltage of the first battery 4 is lower than the voltage of the second battery 6, the current for charging the second battery 6 does not flow from the first battery 4, and the first battery 4 ends up being charged by discharging from the second battery 6. On the other hand, if the voltage of the first battery 4 is significantly higher than that of the second battery 6, the current for charging the second battery 6 flows from the first battery 4. However, the amount of current may become excessively large, which may cause deterioration of the first battery 4, the second battery 6, or the switching elements. Therefore, the control unit 9 determines whether charging is to be completed depending on whether the voltage of the first battery 4 is appropriately higher than that of the second battery 6 or not.

[0054] (Angle condition) In direct charging, the current flowing through the AC rotating electric machine 3 cannot be determined arbitrarily. The magnitude of the current and the direction of charging and discharging can exclude situations that are inappropriate for direct charging based on the above voltage conditions. In addition to the magnitude of the current and the direction of charging and discharging, there are cases where the direction of the current vector must be appropriate. For example, in a permanent magnet synchronous AC rotating electric machine, torque is generated depending on the direction of the current vector. Since charging is usually performed while the vehicle is stopped, it is undesirable for a large torque to be generated that causes the vehicle body to move. It is necessary to determine whether the direction of the current vector flowing in direct charging is appropriate. Therefore, the control unit 9 determines the end of charging based on whether or not any of the absolute values ​​of the angles between the d-axis and each of the phase axes (u-axis, v-axis, and w-axis in a three-phase machine) is less than a predetermined value. Here, each phase axis is an axis along the maximum direction of the fundamental wave magnetomotive force of each phase winding. The d-axis is an axis along which no basic torque is generated even if a current is passed in that direction, and in particular, when there are multiple d-axes within one electrical angle cycle, it is an axis along which a minute torque is generated in the rotation direction that cancels out the increment of the minute displacement of the rotor position with either the positive or negative current. Specifically, in a normal permanent magnet type synchronous AC rotating electric machine, it is an axis along the direction of the rotor magnet magnetic flux, and in a field winding type synchronous AC rotating electric machine, it is an axis along the direction of the salient pole axis. However, in a synchronous reluctance motor, no torque is generated for any current on either the d or q axis, and generally, to align with an interior permanent magnet synchronous AC rotating electric machine in terms of the magnitude of inductance, the one with the smaller inductance is defined as the d axis, and the one with the larger inductance is defined as the q axis. Here, the one with the larger inductance is defined as the d axis, and the one with the smaller inductance is defined as the q axis. Regardless of whether a positive or negative current is passed through a shaft with large inductance, a small displacement of the rotor position generates a torque in the opposite rotational direction to that small displacement. However, regardless of whether a positive or negative current is passed through a shaft with small inductance, a small displacement of the rotor position generates a torque in the same rotational direction as the small displacement. Similarly, the permanent magnets are used as flux barriers to arrange the magnetic flux paths of the rotor, and the dq axes may be selected as described above even for rotating electric machines that obtain output torque using reluctance torque rather than so-called magnet torque.

[0055] (current conditions) For example, if direct charging is started, but a current greater than the target current value is about to flow due to a change in the charging state or temperature, it is better to stop direct charging and switch to another type of charging (step-down charging). In addition, in the case of direct charging, if the current becomes smaller than the target current value, it is better to switch to another charging method (boost charging). Therefore, the control unit 9 may determine that it is inappropriate to perform direct charging when "if the charging current exceeds a value obtained by adding a predetermined value to the target current value during direct charging," "if the charging current continues to be below a value obtained by subtracting a predetermined value from the target current value for a predetermined period of time during step-down charging or direct charging," "if the step-up charging control limit flag is not set during step-up charging," or "if the step-down charging control limit flag is not set during step-down charging."

[0056] When it is determined that direct charging is not appropriate, the control unit 9 determines whether or not to perform step-down charging (step ST6). For example, when the voltage of the first battery 4 is higher than the voltage of the second battery 6 by a predetermined value or more, the control unit 9 determines that it is appropriate to perform step-down charging. When it is determined that it is appropriate to perform step-down charging (step ST6; YES), the control unit 9 proceeds to step ST7 and performs step-down charging. When it is determined that it is not appropriate to perform step-down charging (step ST6; NO), the control unit 9 proceeds to step ST8.

[0057] (Step-down charging) The control unit 9 executes step-down charging (step ST7). Step-down charging is a charging method in which power is transmitted between the first battery 4 and the second battery 6 by repeatedly switching between Mode A and Mode B, using the power stored in a reactor. The winding of the AC rotating electric machine 3 is used as this reactor. Mode A is a mode in which the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the reactor. In addition, mode B is a mode in which the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via a reactor, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected via a reactor. For example, in the case of a positive pattern, the control unit 9 sets the first upper arm switching elements 51u, 51v, and 51w provided in the first drive unit 5, which correspond to phase a, or if phase a corresponds to phase u, sets the first upper arm switching element 51u to a conductive state, and sets the remaining first upper arm switching elements 51v and 51w to an open state. Furthermore, the control unit 9 sets the first lower arm switching elements 52u, 52v, and 52w to a complementary state with the corresponding switching elements among the first upper arm switching elements.

[0058] The control unit 9 sets the second upper arm switching element 71u, 71v, and 71w provided in the second drive unit 7, which corresponds to phase a, or if phase a corresponds to phase u, sets the second upper arm switching element 71u to a conductive state, and sets the remaining second upper arm switching elements 71v and 71w to an open state. Furthermore, the control unit 9 sets the second lower arm switching elements 72u, 72v, and 72w to a complementary state with the corresponding switching elements among the second upper arm switching elements.

[0059] The charge control unit 22 included in the control unit 9 determines a duty ratio according to the degree to which the charge target is not reached, for example, the difference from the charge current target value or the difference from the charge voltage target value, in order to perform switching control so as to satisfy the charge target. Here, the duty ratio is the ratio of time during which the switching element is in a conductive state or an open state in a certain period, and can take a value between 0 and 1.

[0060] In the following description, the duty ratio at which the upper arm switching element is in a conductive state is referred to as an on-duty, and the duty ratio at which the upper arm switching element is in an open state is referred to as an off-duty. The control unit 9 calculates the target current for each phase from the charging current target value, and performs feedback control so that the current actually flowing through each phase, i.e., the detection value of the current sensor, coincides with the target current for each phase.

[0061] The target current value for each phase of the n-phase machine will now be described. Using the following formula (1), which is an n-th order algebraic equation for z, the real parts of n non-overlapping complex solutions are set as the target current values ​​for each of the n phases. Of the n non-overlapping complex solutions, the real part of the solution whose absolute value of the argument is the smallest is set as the target current value for the a phase. The control unit 9 associates the solutions other than the solution associated with the a phase with the solutions corresponding to the b phase, the c phase, and the d phase in order of increasing argument, up to the nth phase. The argument is considered to be a principal value between 0 degrees and 360 degrees. * is the charging current target value, j is the imaginary unit, and θ is the target current phase. The target current phase is the target value of the directional angle from the a-axis of the current vector taking into account all the currents of each phase. (e -jθ zcosθ / i * ) n =1 (1)

[0062] In the case of a three-phase machine, the target current value of each phase is specifically calculated from the following formula (2). In the following formula (2), i * is the charging current target value, and i * a is the target current value of phase a, and i * b is the target current value of phase b, and i * c is the target current value of phase c. i * a =i * i * b ={cos(θ+2π / 3) / cosθ}i * i * c ={cos(θ-2π / 3) / cosθ}i * (2)

[0063] There are two methods for setting the target current phase: The first setting method is to set the target current phase to zero. With this setting, both the maximum phase current and the sum of squares of the phase currents required to obtain the same charging current are smaller than with other settings. In other words, there is an advantage that Joule loss can be reduced or an element with a small current rating can be used. On the other hand, the set current phase is slightly shifted from the phase where the torque is zero, and some torque may be generated.

[0064] The second setting method is to set the target current phase at a directed angle from the positive direction of the a-axis to the positive direction of the d-axis. With this setting, ideally the torque generated by the rotating electric machine is zero, and no unnecessary torque is generated during charging. In other words, in an AC rotating electric machine provided in a device in which undesirable motion is caused when torque is generated, there is an advantage that a locking mechanism that mechanically restrains the undesirable motion so as to prevent the undesirable motion is not required, or a simple one is sufficient. It should be noted that the positive d-axis direction is usually calculated based on the value obtained from the angle sensor 8, but this value may contain some error. In this case, rather than continuing to calculate the target current phase θ during charging and resetting the target current value, it is desirable to continue to use the value obtained before the start of charging during charging, unless there is a significant change in the angle, such as a change in which phase is designated as phase a.

[0065] A specific feedback control method for making the current of each phase follow the current target value of each phase is, for example, a proportional-integral control method in which the plant output (controlled amount) is the current value of each phase from phase b onwards, and the plant input (operated amount) is the applied voltage to each phase from phase b onwards. To convert the applied voltage into a duty ratio, the following (1) and (2) are taken into consideration. (1) The conversion must be performed taking into account that the upper arm switching element of phase a is always in a conductive state and the lower arm switching element is always in an open state. (2) If saturation occurs when converting the applied voltage of each phase into a duty ratio, it is desirable to scale down the applied voltage of each phase to the saturation limit while maintaining the ratio between the applied voltages of each phase. In addition, anti-windup processing of the proportional-integral controller may be performed.

[0066] In the case where the AC rotating electric machine 3 is a three-phase machine, with regard to (2), the charging control unit 22 clips the applied voltage of each phase determined by a feedback control system such as proportional-integral control at a saturation limit. FIG. 7 is a diagram showing the applicable voltage limit and the clipping of the voltage command in step-down charging. As shown in FIG. 7, the range in which the applied voltages vb and vc can be output is inside a parallelogram. That is, point P (V 1 / 3,ΔV 2 / 3), point B is ((V 2 +V 1 ) / 3,(V 2 -2V 1 ) / 3), point C is ((V 2 -2V 1 ) / 3,(V 2 +V 1 ) / 3), point Z is ((V 2 -V 1 ) / 3,(V 2 -V 1 ) / 3) are the interior of a parallelogram with vertices V 1 is the voltage of the first battery 4 (the value detected by the voltage sensor), and V 2 is the voltage of the second battery 6 (the value detected by the voltage sensor).

[0067] Let us assume that the applied voltage command values ​​(vb and vc) for each phase, indicated by the dashed arrows in Fig. 7, are obtained from a feedback control system. In this case, they are outside the range (parallelogram shown in the figure) that can be output as applied voltages, and cannot be output. As indicated by the solid arrows in Fig. 7, these are clipped so that they fall within the parallelogram while maintaining the direction of the dashed arrows.

[0068] Next, we will explain how to convert the duty ratio in relation to (1). Point z is taken as the starting point of the position vector. In Fig. 7, the position of a point inside the parallelogram can be expressed as a linear sum of the position vector indicating point B and the position vector indicating that point, and the coefficient is between 0 and 1. Based on this, in order to convert the applied voltage indicated at a point inside the parallelogram into a duty ratio, when the position vector is expressed as a linear sum of the position vector indicating point B and the position vector indicating point C, the coefficient of the position vector indicating point B is taken as the duty ratio of phase b, and the coefficient of the position vector indicating point C is taken as the duty ratio of phase c. When the pattern is positive, the on-duty is obtained by the above-mentioned process, and when the pattern is negative, the off-duty is obtained.

[0069] The above-mentioned process is similar to that for an n-phase machine. The control unit 9 scales the applied voltage command values ​​(vb, vc, vd,...) obtained from the feedback control system while maintaining their orientation so that they are within a hypercube that indicates the range in which they can be output as applied voltages. The control unit 9 performs similar control for the b-phase and subsequent phases without changing the premise that the upper arm switching element is always in a conductive state and the lower arm switching element is always in an open state in the a-phase. That is, the control unit 9 defines the points corresponding to the n-phase as point B, which is the point that indicates the voltage vector when only the b-phase is in a conductive state and the other phases are in an open state, point C, which is the point that indicates the voltage vector when only the c-phase is in a conductive state and the other phases are in an open state, point D, which is the point that indicates the voltage vector when only the d-phase is in a conductive state and the other phases are in an open state, and so on.

[0070] Point Z, which is the starting point of the position vector, is the point that indicates the voltage vector when all phases from b onwards are open. The points inside the hypercube that indicate the range that can be output as applied voltage can be expressed as a linear sum of the position vectors that indicate the points defined by turning on only one phase from point B onwards. In this case, just like with three phases, the duty ratios of phases other than a, which are fixed in the open state, are found by using the coefficient of the position vector of point B as the duty ratio of phase b, the coefficient of the position vector of point C as the duty ratio of phase c, and the coefficient of the position vector of point D as the duty ratio of phase d.

[0071] When a phase is described as being on, it means that the upper arm switching element in that phase is in a conductive state and the lower arm switching element is in an open state, and when it is described as being off, it means that, opposite to on, the upper arm switching element is in an open state and the lower arm switching element is in a conductive state. The above describes the case of a positive pattern in step-down charging. In the case of a negative pattern, the same explanation holds true by reversing the axis of each phase (u-phase, v-phase, w-phase, etc.) (switching the positive and negative directions). Reversing the axis of each phase not only reverses the sign of the current detection value, but also reverses the output voltage, that is, fixing the a-phase from fixed on to fixed off. Where on-duty is sought, it should be interpreted as seeking off-duty.

[0072] FIG. 8 is a table showing the open and conductive states of the switching elements in step-down charging. "SW" in FIG. 8 indicates a switching element that is subject to switching control based on a duty ratio. When the AC rotating electric machine 3 is a three-phase machine, the control unit 9 sets the switching elements to a conductive state or an open state in step-down charging control as shown in FIG. 8. In this way, in step-down charging, the step-down charging is performed by power transmitted between the first battery 4 and the second battery 6 by changing the conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element (the element corresponding to "SW").

[0073] Fig. 9 is a table showing the open state and the conductive state of the switching elements in each mode in step-down charging. As shown in Fig. 9, for example, in the d-axis range (1) (-30 degrees to 30 degrees), in mode A, the first upper arm switching elements 51v and 51w are in a conductive state, and the first lower arm switching elements 52v and 52w are in an open state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected through the winding of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51v and 51w are in an open state, and the first lower arm switching elements 52v and 52w are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected through the winding of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (2) (30 degrees to 90 degrees), in mode A, the first upper arm switching elements 51u and 51v are in an open state, and the first lower arm switching elements 52u and 52v are in a conductive state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51u and 51v are in a conductive state, and the first lower arm switching elements 52u and 52v are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (3) (90 degrees to 150 degrees), in mode A, the first upper arm switching elements 51u and 51w are in a conductive state, and the first lower arm switching elements 52u and 52w are in an open state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51u and 51w are in an open state, and the first lower arm switching elements 52u and 52w are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (4) (150 degrees to 210 degrees), in mode A, the first upper arm switching elements 51v and 51w are in an open state, and the first lower arm switching elements 52v and 52w are in a conductive state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51v and 51w are in a conductive state, and the first lower arm switching elements 52v and 52w are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (5) (210 degrees to 270 degrees), in mode A, the first upper arm switching elements 51u and 51v are in a conductive state, and the first lower arm switching elements 52u and 52v are in an open state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51u and 51v are in an open state, and the first lower arm switching elements 52u and 52v are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (6) (270 degrees to 330 degrees), in mode A, the first upper arm switching elements 51u and 51w are in an open state, and the first lower arm switching elements 52u and 52w are in a conductive state, so that the positive electrode of the second battery 6 and the negative electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the first upper arm switching elements 51u and 51w are in a conductive state, and the first lower arm switching elements 52u and 52w are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In this manner, in step-down charging, by repeatedly switching between mode A and mode B, the power stored in the windings of the AC rotating electric machine 3 is transmitted between the first battery 4 and the second battery 6, thereby charging the second battery 6.

[0074] As step-down charging progresses, even if the voltage of the second battery 6 is sufficiently lower than the voltage of the first battery 4 at the start of step-down charging, the second battery 6 is charged and reaches a voltage close to that of the first battery 4. In this case, step-down charging cannot charge the battery with a sufficient current. For this reason, the control unit 9 sets a step-down charging limit flag and determines in step ST4 that direct charging should be performed.

[0075] (Boost charging) The control unit 9 executes boost charging (step ST8). Boost charging is charging in which power is transmitted between the first battery 4 and the second battery 6 by using power stored in a reactor by repeatedly switching between mode C and mode B. A winding of the AC rotating electric machine 3 is used as this reactor. Mode B is a mode in which the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via a reactor, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected via a reactor. Mode C is a mode in which the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via a reactor. For example, in the case of a positive pattern, the control unit 9 sets the first upper arm switching elements 51u, 51v, and 51w included in the first drive unit 5, which correspond to the a-phase, in a conductive state and sets the remaining switching elements in an open state. The control unit 9 sets the first lower arm switching elements 52u, 52v, and 52w in a complementary state with the switching elements corresponding to the first upper arm switching elements. The control unit 9 also brings the second upper arm switching elements 71u, 71v, and 71w included in the second drive unit 7 into a conductive state, and controls the switching of the remaining switching elements according to the charging state. For example, the control unit 9 brings the first lower arm switching elements 52u, 52v, and 52w into a complementary state with the switching elements corresponding to the first upper arm switching elements.

[0076] The switching control is performed so as to satisfy the charging target. For example, the on-duty is determined according to the degree to which the charging target is not reached, that is, the difference from the charging current target value or the difference from the charging voltage target value. This is a control in which the on-duty is reduced as the charging target is approached, but in the boost charging control, more complicated control or phase compensation may be involved. For example, the control unit 9 determines a target current for each phase from the charging current target value, and performs feedback control so that the current actually flowing through each phase (obtained as a detection value of a current sensor) coincides with the target current for each phase.

[0077] The difference between the target current value and step-down charging will be described below. As with step-down charging, the current target value for each phase is calculated, but the difference with step-up charging is that it is multiplied by a correction coefficient K. That is, the real part of the solution to the above equation (1) is multiplied by the correction coefficient K, and then the correction coefficient K is assigned to each phase according to the same rules as with step-down charging. In step-down charging, the current flowing through phase a is constantly charging; in other words, taking into account that the sum of the currents of all phases is zero, the current with the sign of the inverted sum of the currents of each phase other than phase a is constantly charging; however, this is not the case with step-up charging. For example, in boost charging, the contribution of phase b current to the charging current only occurs when phase b is off, and does not contribute to the charging current when phase b is on. In this way, the contribution of the current of each phase other than phase a to the charging current depends on the off-duty of each phase. That is, for each phase other than phase a, the sum of the absolute value of the current target value of each phase multiplied by the off-duty of that phase is the time-averaged charging current with the sign inverted.

[0078] As a result, the control unit 9 can estimate the ratio of the charging current that will actually be used to the charging current target value by estimating the off-duty of each phase during steady charging, and can accurately control the charging current by setting, for example, the reciprocal of that ratio as a correction coefficient according to that ratio. Methods for estimating the off-duty of each phase can be roughly divided into methods based on pre-calculation prior to current feedback control and methods based on post-estimation according to current feedback control.

[0079] A representative example of a pre-calculation is one based on the voltage ratio between the first battery 4 and the second battery 6. A more accurate pre-calculation can be achieved by taking into account the target current of each phase, the equivalent resistance of the current path, or the dead-time voltage, etc., which are set in advance as predetermined values.

[0080] In the method of post-estimation, the equivalent resistance or the substantial dead-time voltage is adaptively estimated, estimated by a disturbance observer, or successively updated by the same calculation as the pre-calculation. Alternatively, the actual duty command of each phase may be passed through a low-pass filter with a time constant longer than the control system response to replace the duty ratio of each phase. Alternatively, the charging current to the battery may be detected and passed through a low-pass filter that usually blocks high-frequency components higher than the switching period to obtain an actual charging current estimate, and the ratio to the charging current target value may be directly calculated without using the duty ratio. As described above, during boost charging, after obtaining an appropriate current target value for each phase, feedback control is performed so that the current of each phase follows the target value, similarly to step-down charging.

[0081] In the case of a three-phase machine, a specific procedure for using proportional-integral control for feedback control similar to step-down charging will be described below, focusing on the differences from step-down charging. FIG. 10 is a diagram showing the applicable voltage limit and the clipping of the voltage command in boost charging. As shown in FIG. 10, in boost charging, when the applied voltage of each phase determined by a feedback control system such as proportional-integral control is clipped at the saturation limit, the applicable voltage range differs. The range in which the applied voltages vb and vc can be output is inside a parallelogram as shown in FIG. 10. In other words, at point Z ((V 2 -V 1 ) / 3,(V 2 -V 1 ) / 3), point B is ((2V 2 -V 1 ) / 3,(-V 2 -V 1 ) / 3), point C((-V 2 -V 1 ) / 3,(2V 2 -V 1 ) / 3), point P is (-V 1 / 3,-V 1 / 3) are the vertices of a parallelogram.

[0082] The method of clipping is the same as in step-down charging. In other words, let us say that the applied voltage command values ​​(vb and vc) for each phase as shown by the dashed arrows in Figure 10 are obtained from the feedback control system. This is outside the range that can be output as the applied voltage (parallelogram in Figure 10) and cannot be output. As shown by the solid arrow, this is clipped so that it fits inside the parallelogram while maintaining the direction of the dashed arrow.

[0083] The conversion of the duty cycle is performed using the same logic as in step-down charging. For example, point z is taken as the starting point of the position vector. In FIG. 10, the position of a point inside the parallelogram can be expressed as a linear sum of a position vector indicating point B and a position vector indicating that point, and the coefficient is 0 or more and 1 or less. Based on this, in order to convert the applied voltage indicated by a point inside the parallelogram into a duty ratio, when the position vector is expressed as a linear sum of a position vector indicating point B and a position vector indicating point C, the coefficient of the position vector indicating point B is set as the duty ratio of the b phase, and the coefficient of the position vector indicating point C is set as the duty ratio of the c phase. When the AC rotating electric machine 3 is a three-phase machine, as described above, the positions of the points are different from those in step-down charging, but the calculation logic is the same as in step-down charging. The same is true for n-phase machines.

[0084] Up to this point, the positive pattern in voltage boost charging has been described. In the case of a negative pattern, the same explanation can be made by inverting the axis of each phase (u-phase, v-phase, w-phase, etc.) (switching the positive and negative directions). This is the same as step-down charging.

[0085] Fig. 11 is a table showing the open and conductive states of switching elements in boost charging. In Fig. 11, "SW" indicates a switching element that is subject to switching control based on a duty ratio. In this manner, in boost charging, boost charging is performed by power transmitted between the first battery 4 and the second battery 6 by changing the conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element (the element corresponding to "SW"). If the AC rotating electric machine 3 is a three-phase machine, the control unit 9 sets the switching elements in a conductive state or an open state during boost charging, as shown in FIG. 11. During boost charging, for example, the first battery 4 may be charged from the outside at the same time. In such a case, the voltage of the second battery 6 is sufficiently higher than the voltage of the first battery 4 at the start of boost charging, but the first battery 4 is charged and reaches a voltage close to that of the second battery 6. In this case, the above-mentioned boost charging limit flag is set, and it is determined in step ST3 that direct charging should be performed.

[0086] Fig. 12 is a table showing the open state and the conductive state of the switching elements in each mode in boost charging. As shown in Fig. 9, for example, in the d-axis range of region (1) (-30 degrees to 30 degrees), in mode C, the second upper arm switching elements 71v and 71w are in a conductive state, and the second lower arm switching elements 72v and 72w are in an open state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected through the winding of the AC rotating electric machine 3. In mode B, contrary to mode A, the second upper arm switching elements 71v and 71w are in an open state, and the second lower arm switching elements 72v and 72w are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected through the winding of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In boost charging, the second battery 6 is charged by repeatedly switching between Mode C and Mode B to transmit and receive the electric power stored in the windings of the AC rotating electric machine 3 between the first battery 4 and the second battery 6. In the d-axis range (2) (30 degrees to 90 degrees), in mode C, the second upper arm switching elements 71u and 71v are in an open state, and the second lower arm switching elements 72u and 72v are in a conductive state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the second upper arm switching elements 71u and 71v are in a conductive state, and the second lower arm switching elements 72u and 72v are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (3) (90 degrees to 150 degrees), in mode C, the second upper arm switching elements 71u and 71w are in a conductive state, and the second lower arm switching elements 72u and 72w are in an open state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the second upper arm switching elements 71u and 71w are in an open state, and the second lower arm switching elements 72u and 72w are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (4) (150 degrees to 210 degrees), in mode C, the second upper arm switching elements 71v and 71w are in an open state, and the second lower arm switching elements 72v and 72w are in a conductive state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the second upper arm switching elements 71v and 71w are in a conductive state, and the second lower arm switching elements 72v and 72w are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (5) (210 degrees to 270 degrees), in mode C, the second upper arm switching elements 71u and 71v are in a conductive state, and the second lower arm switching elements 72u and 72v are in an open state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the second upper arm switching elements 71u and 71v are in an open state, and the second lower arm switching elements 72u and 72v are in a conductive state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In the d-axis range (6) (270 degrees to 330 degrees), in mode C, the second upper arm switching elements 71u and 71w are in an open state, and the second lower arm switching elements 72u and 72w are in a conductive state, so that the positive electrode of the first battery 4 and the negative electrode of the first battery 4 are electrically connected via the windings of the AC rotating electric machine 3. In mode B, the second upper arm switching elements 71u and 71w are in a conductive state, and the second lower arm switching elements 72u and 72w are in an open state, so that the positive electrode of the first battery 4 and the positive electrode of the second battery 6 are electrically connected via the windings of the AC rotating electric machine 3, and the negative electrode of the first battery 4 and the negative electrode of the second battery 6 are electrically connected. In this way, in boost charging, by repeatedly switching between mode C and mode B, the power stored in the windings of the AC rotating electric machine 3 is transmitted between the first battery 4 and the second battery 6, thereby charging the second battery 6.

[0087] Here, a supplementary explanation will be given regarding the execution order of this charging sequence. For convenience of explanation, the sequence shown in Fig. 3 has been explained as a sequential execution sequence, but it is not necessary to execute it sequentially. For example, when the function of the control unit 9 is implemented as software on a microcomputer having an interrupt function, each charging control of step ST4, step ST7, and step ST8 may be processed as an interrupt routine for every integer multiple of a half cycle of PWM, and the charging end determination in step ST5 and the charging target setting (step ST2) that may be executed after this step may be implemented as a time interruption different from the interrupt cycle of each charging (typically longer cycle).

[0088] (Direct charging in n-phase machines) For example, in the positive pattern, the control unit 9 selects candidates for a phase for making the upper arm switching element conductive and a phase for making the lower arm switching element conductive. Here, if the inner product of the axial direction vector of a phase and the axial direction vector of phase a is positive, the candidate is a phase for making the upper arm switching element conductive. If it is negative, the candidate is a phase for making the lower arm switching element conductive. At least one of the candidates for the phases that cause the upper arm switching element to be conductive is selected as the phase that actually causes the upper arm switching element to be conductive. At least one of the candidates for the phases that cause the lower arm switching elements to be conductive is selected as the phase that actually causes the lower arm switching elements to be conductive. For a phase selected as the phase in which to make the upper arm switching elements conductive, the control unit 9 places the upper arm switching elements corresponding to that phase in both the first drive unit 5 and the second drive unit 7 in a conductive state, and places the lower arm switching elements in an open state. Furthermore, for the phase selected as the phase for conducting the lower arm side, the control unit 9 places the upper arm switching elements corresponding to that phase of both the first drive unit 5 and the second drive unit 7 in an open state and places the lower arm switching elements in a conducting state. In addition, if the AC rotating electric machine 3 is a special rotating machine having a phase where the inner product with the axial direction of phase a is zero, it may be included as a candidate for conducting either the upper arm side or the lower arm side.

[0089] If it is a negative pattern, the control unit 9 uses the selection criteria for phase candidates for turning on the upper arm switching element in the positive pattern as the selection criteria for phase candidates for turning on the lower arm switching element in the negative pattern. Similarly, the control unit 9 uses the selection criteria for phase candidates for turning on the lower arm switching elements in the positive pattern as the selection criteria for phase candidates for turning on the upper arm switching elements in the negative pattern.

[0090] For a phase that is not to be actually turned on for the upper arm or the lower arm, the control unit 9 opens the switching elements of the phase on both the upper arm side and the lower arm side. The phase to be actually turned on may be selected from among the candidates by selecting at least one on the upper arm side and at least one on the lower arm side. The following two selection methods are particularly preferred. (1) Ensure that all candidates are actually successful. (2) Select phase a, and if it is a positive pattern, select it as the phase that actually conducts the upper arm, and if it is a negative pattern, select it as the phase that actually conducts the lower arm. Select the phase that is most different in direction from phase a, that is, the phase for which the dot product of the directional vector of each axis and the directional vector in the a-axis direction is the smallest negative value. If it is a positive pattern, select it as the phase that actually conducts the lower arm, and if it is a negative pattern, select it as the phase that actually conducts the upper arm. In addition, there are two phases whose direction differs most from phase a when n is an odd number, and one when n is an even number. Usually, the number of phases n is odd, so there are two phases whose direction differs most from phase a.

[0091] Fig. 13 is a table showing the d-axis range, the corresponding a, b, c, d and e phases, their positive and negative polarities, and the open and conductive states of the switching elements in direct charging control. As mentioned above, there is no unique way to decide which switching elements should be in a conductive or open state so that direct charging control is possible. The table shows the cases when conductive and open are selected for a five-phase machine using the selection criterion (1) above.

[0092] In the above explanation, a synchronous motor has been taken as an example of the AC rotating electric machine 3. With a synchronous motor, the torque generated during charging can be reduced, or ideally reduced to zero, by appropriately setting the a-phase selection and the target current phase. When an induction motor known as an asynchronous machine is used as the AC rotating electric machine 3, any phase such as the u-phase or v-phase may be selected as the a-phase unless there is a particular reason not to do so.

[0093] Furthermore, the target current phase may be set to zero unless there is a particular reason not to do so. An example of the special reason is temperature protection. For example, if the a-phase is set as the u-phase when the first upper arm switching element 51u of the u-phase is hotter than any other element, the largest current flows through the first upper arm switching element 51u among the switching elements, and the first upper arm switching element 51u becomes even hotter. In this case, by selecting a phase other than the u-phase as the a-phase, it is possible to prevent current from flowing through the hot first upper arm switching element 51u.

[0094] Next, a hardware configuration for realizing the functions of the control unit 9 will be described. The current command generating unit 21, the charging control unit 22, and the switching signal generating unit 23 included in the control unit 9 are realized by processing circuits. That is, the control unit 9 includes a processing circuit for executing each process from step ST1 to step ST8 shown in Fig. 3. The processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in a memory.

[0095] Fig. 14A is a block diagram showing a hardware configuration for realizing the functions of the control unit 9. Fig. 14B is a block diagram showing a hardware configuration for executing software for realizing the functions of the control unit 9. In Figs. 14A and 14B, the input interface 100 is, for example, an interface that relays a detection signal output from a sensor to the control unit 9. The output interface 101 is an interface that relays a control signal output from the control unit 9 to the first drive unit 5 and the second drive unit 7.

[0096] 14A, the processing circuit 102 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these. The functions of the current command generating unit 21, the charging control unit 22, and the switching signal generating unit 23 included in the control unit 9 may be realized by separate processing circuits, or these functions may be realized together by one processing circuit.

[0097] 14B, the functions of the current command generating unit 21, the charging control unit 22, and the switching signal generating unit 23 included in the control unit 9 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 104.

[0098] The processor 103 reads out and executes the programs stored in the memory 104 to realize the functions of the current command generating unit 21, the charging control unit 22, and the switching signal generating unit 23 included in the control unit 9. For example, the control unit 9 includes a memory 104 for storing a program that, when executed by the processor 103, results in the processing of steps ST1 to ST8 shown in FIG. 3 being executed. These programs cause a computer to execute the procedure or method of the processing performed by the control unit 9. The memory 104 may be a computer-readable storage medium in which a program for causing a computer to function as the control unit 9 is stored.

[0099] Memory 104 may be, for example, a non-volatile or volatile semiconductor memory such as a Random Access Memory (RAM), a Read Only Memory (ROM), a flash memory, an Erasable Programmable Read Only Memory (EPROM), an Electrically-EPROM (EEPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD, etc.

[0100] Some of the functions of current command generating unit 21, charging control unit 22, and switching signal generating unit 23 included in control unit 9 may be realized by dedicated hardware, and the remaining functions may be realized by software or firmware. For example, the function of current command generating unit 21 is realized by processing circuit 102, which is dedicated hardware, and the functions of charging control unit 22 and switching signal generating unit 23 are realized by processor 103 reading and executing a program stored in memory 104. Thus, the processing circuitry may implement the above-described functions through hardware, software, firmware or a combination of these.

[0101] As described above, in the control device 2 of embodiment 1, in an AC rotating electric machine 3 in which the first battery 4 and the second battery 6 are insulated from each other except by paths including the windings, the control unit 9 transmits and receives power between the first battery 4 and the second battery 6 in order to charge either the first battery 4 or the second battery 6 by setting the open or charged state of each of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w. In this way, the control device 2 is a "power supply isolated type" in which the first battery 4 and the second battery 6 are insulated from each other except through paths including the windings, and no common mode current flows through the windings of the AC rotating electric machine 3, and charges either the first battery 4 or the second battery 6 using power transmitted between the first battery 4 and the second battery 6 by setting the switching element of the drive unit to an open or conductive state. The control device 2 does not have the components described in Patent Document 1 that reduce the voltage utilization rate, and therefore can increase the voltage utilization rate. Furthermore, since the control device 2 charges either the first battery 4 or the second battery 6 using the power transmitted and received between the first battery 4 and the second battery 6, it is only necessary to connect a charging device to either the first drive unit or the second drive unit, thereby avoiding an increase in the size of the device.

[0102] In the control device 2 according to the first embodiment, the control unit 9 fixedly sets the conduction states of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w, thereby transmitting and receiving power between the first battery 4 and the second battery 6 in order to directly charge either the first battery 4 or the second battery 6. When the voltages of the first battery 4 and the second battery 6 are close to each other, power can be transmitted and received appropriately.

[0103] In the control device 2 according to the first embodiment, the control unit 9 changes the conduction state of any of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to transmit and receive power between the first battery 4 and the second battery 6 in order to perform step-down charging of either the first battery 4 or the second battery 6. When the voltage of the first battery 4 is higher than the voltage of the second battery 6, power can be transmitted and received preferably.

[0104] In the control device 2 according to the first embodiment, the control unit 9 changes the conduction state of any of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to transmit and receive power between the first battery 4 and the second battery 6 in order to boost charge either the first battery 4 or the second battery 6. When the voltage of the first battery 4 is lower than the voltage of the second battery 6, power can be transmitted and received appropriately.

[0105] In the control device 2 according to the first embodiment, the control unit 9 transmits and receives power between the first battery 4 and the second battery 6 by fixedly setting the conductive states of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to perform direct charging of either the first battery 4 or the second battery 6, and transmits and receives power between the first battery 4 and the second battery 6 by fixedly setting the conductive states of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to perform step-down charging of either the first battery 4 or the second battery 6. The power is exchanged between the first battery 4 and the second battery 6 by changing the conduction state of any of the switching elements 71u, 71v, and 71w and the second lower arm switching elements 72u, 72v, and 72w, and the power is exchanged between the first battery 4 and the second battery 6 by changing the conduction state of any of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w in order to boost charge either the first battery 4 or the second battery 6, depending on the charging state. Power can be exchanged suitably regardless of the voltage of the first battery 4 and the voltage of the second battery 6.

[0106] In the control device 2 according to the first embodiment, the control unit 9 includes a current command generating unit 21 that generates a current command indicating a current to be set in the AC rotating electric machine 3, and a switching signal generating unit that generates switching signals that switch between an open state and a conductive state of each of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w. and a charge control unit 22 that transmits and receives power between the first battery 4 and the second battery 6 in order to charge either the first battery 4 or the second battery 6 by setting the open or conductive state of each of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w. This enables the control device 2 to increase the voltage utilization rate.

[0107] In the control device 2 according to the first embodiment, the charge control section 22 sets any one of the first upper arm switching elements 51u, 51v, and 51w and any one of the second upper arm switching elements 71u, 71v, and 71w corresponding thereto in a conductive state, sets any one of the first lower arm switching elements 52u, 52v, and 52w and any one of the second lower arm switching elements 72u, 72v, and 72w corresponding thereto in an open state, and changes the conductive states of the remaining elements other than the elements set in the conductive state and the open state. This enables the control device 2 to increase the voltage utilization rate.

[0108] In the control device 2 according to the first embodiment, the current command generating unit 21 generates a current command for controlling the amount of current flowing through the windings to have a predetermined relationship. An appropriate amount of power can be transmitted and received without causing overcharging or over-discharging.

[0109] The power storage drive system 1 according to the first embodiment includes an AC rotating electric machine 3 and a control device 2. This makes it possible to provide a power storage drive system 1 capable of increasing the voltage utilization rate.

[0110] In the control method according to the first embodiment, the control unit 9 included in the control device 2 sets the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to open or conductive, respectively, thereby transmitting and receiving power between the first battery 4 and the second battery 6 in order to charge either the first battery 4 or the second battery 6. By the control unit 9 executing this method, it is possible to increase the voltage utilization rate.

[0111] In the control method according to the first embodiment, the control unit 9 fixedly sets the conduction states of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w to perform direct charging of either the first battery 4 or the second battery 6, thereby transmitting and receiving power between the first battery 4 and the second battery 6, and In order to boost charge either the first battery 4 or the second battery 6, the control unit 9 switches between transmitting and receiving power between the first battery 4 and the second battery 6 by changing the conduction state of any of the first upper arm switching elements 51u, 51v, and 51w, the first lower arm switching elements 52u, 52v, and 52w, the second upper arm switching elements 71u, 71v, and 71w, and the second lower arm switching elements 72u, 72v, and 72w, depending on the charging status. By the control unit 9 executing this method, it is possible to increase the voltage utilization rate.

[0112] Various aspects of the present disclosure are summarized below as appendices.

[0113] (Appendix 1) a first drive unit for driving an AC rotating electric machine having a stator with a multi-phase winding and a rotor, the multi-phase windings not being connected to each other, the first drive unit having a plurality of first upper arm switching elements and a plurality of first lower arm switching elements, all of one ends of the first upper arm switching elements on a high potential side being connected to a positive electrode of a first battery, the other ends of the plurality of first upper arm switching elements being connected to one ends of the corresponding first lower arm switching elements on a high potential side and to one ends of the multi-phase windings, and the other ends of the plurality of first lower arm switching elements being all connected to a negative electrode of the first battery; a second drive unit that drives the AC rotating electric machine, the second drive unit having a plurality of second upper arm switching elements and a plurality of second lower arm switching elements, one ends of the second upper arm switching elements on the high potential side all connected to a positive electrode of a second battery that is insulated from the first battery and from each other except for a path including the winding, the other ends of the plurality of second upper arm switching elements each connected to one end of the second lower arm switching element on the high potential side corresponding to the second lower arm switching element and the other ends of the winding of multiple phases, and the other ends of the plurality of second lower arm switching elements all connected to a negative electrode of the second battery; a control unit that sets an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to charge either the first battery or the second battery. A control device comprising: (Appendix 2) The control unit transmits and receives electric power between the first battery and the second battery in order to directly charge either the first battery or the second battery by setting fixed conductive states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. 2. The control device according to claim 1 . (Appendix 3) The control unit changes a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to perform step-down charging of either the first battery or the second battery. 3. The control device according to claim 1 or 2, (Appendix 4) The control unit changes a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to boost charge either the first battery or the second battery. 4. The control device according to claim 1, (Appendix 5) The control unit is transmitting and receiving electric power between the first battery and the second battery by fixing the conduction states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to directly charge either the first battery or the second battery; transmitting and receiving power between the first battery and the second battery by changing a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to perform step-down charging of either the first battery or the second battery; In order to perform boost charging of either the first battery or the second battery, a conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element is changed to switch between transmission and reception of power between the first battery and the second battery according to a charging state. 2. The control device according to claim 1 . (Appendix 6) The control unit is a current command generating unit that generates a current command indicating a current to be set in the AC rotating electric machine; a switching signal generating unit that generates switching signals that switch between an open state and a conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element; a charge control unit that transmits and receives power between the first battery and the second battery in order to charge either the first battery or the second battery by setting an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. 6. The control device according to claim 1, (Appendix 7) The charge control unit sets any one of the plurality of first upper arm switching elements and one of the corresponding second upper arm switching elements to a conductive state, sets any one of the plurality of first lower arm switching elements and one of the plurality of second lower arm switching elements corresponding to these elements to an open state, and changes the conductive states of the remaining elements other than the elements set to the conductive state and the open state. 7. The control device according to claim 6, (Appendix 8) The current command generating unit generates the current command for controlling the amount of current flowing through the windings so that the amount of current flowing through the windings satisfies a predetermined relationship. 8. The control device according to claim 6 or 7, (Appendix 9) the AC rotating electric machine having a stator provided with the windings of a plurality of phases and a rotor, the windings of the plurality of phases not being connected to each other; A control device according to any one of Supplementary Note 1 to Supplementary Note 8, The power storage drive system is characterized by the above. (Appendix 10) a first drive unit for driving an AC rotating electric machine having a stator with a multi-phase winding and a rotor, the multi-phase windings not being connected to each other, the first drive unit having a plurality of first upper arm switching elements and a plurality of first lower arm switching elements, all of one ends of the first upper arm switching elements on a high potential side being connected to a positive electrode of a first battery, the other ends of the plurality of first upper arm switching elements being connected to one ends of the corresponding first lower arm switching elements on a high potential side and to one ends of the multi-phase windings, and the other ends of the plurality of first lower arm switching elements being all connected to a negative electrode of the first battery; a second drive unit that drives the AC rotating electric machine, the second drive unit having a plurality of second upper arm switching elements and a plurality of second lower arm switching elements, one ends of the second upper arm switching elements on a high potential side all connected to a positive electrode of a second battery that is insulated from the first battery except for a path including the winding, the other ends of the plurality of second upper arm switching elements are connected to one ends of the second lower arm switching elements on a high potential side corresponding to each of the second lower arm switching elements and to other ends of the windings of multiple phases, and the other ends of the plurality of second lower arm switching elements all connected to a negative electrode of the second battery, A control unit sets an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to charge either the first battery or the second battery. A control method comprising: (Appendix 11) The control unit: transmitting and receiving electric power between the first battery and the second battery by fixing the conduction states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to directly charge either the first battery or the second battery; transmitting and receiving power between the first battery and the second battery by changing a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to perform step-down charging of either the first battery or the second battery; In order to perform boost charging of either the first battery or the second battery, a conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element is changed to switch between transmission and reception of power between the first battery and the second battery according to a charging state. 11. The control method according to claim 10,

[0114] Any of the components of the embodiments may be modified or omitted. [Explanation of symbols]

[0115] 1 Energy storage drive system, 2 Control device, 3 AC rotating electric machine, 4 First battery, 5 First drive unit, 6 Second battery, 7 Second drive unit, 8 Angle sensor, 9 Control unit, 21 Current command generation unit, 22 Charging control unit, 23 Switching signal generation unit, 31u, 31v, 31w Winding, 51N, 51P DC bus, 51u, 51v, 51w First upper arm switching element, 52u, 52v, 52w First lower arm switching element, 53, 73 Smoothing capacitor, 55 Current sensor, 55u, 55v, 55w, 74u, 74v, 74w AC electric wire, 71u, 71v, 71w Second upper arm switching element, 72u, 72v, 72w Second lower arm switching element, 100 Input interface, 101 Output interface, 102 Processing circuit, 103 Processor, 104 memory.

Claims

1. a first drive unit for driving an AC rotating electric machine having a stator with a multi-phase winding and a rotor, the multi-phase windings not being connected to each other, the first drive unit having a plurality of first upper arm switching elements and a plurality of first lower arm switching elements, all of one ends of the first upper arm switching elements on a high potential side being connected to a positive electrode of a first battery, the other ends of the plurality of first upper arm switching elements being connected to one ends of the corresponding first lower arm switching elements on a high potential side and to one ends of the multi-phase windings, and the other ends of the plurality of first lower arm switching elements being all connected to a negative electrode of the first battery; a second drive unit that drives the AC rotating electric machine, the second drive unit having a plurality of second upper arm switching elements and a plurality of second lower arm switching elements, one ends of the second upper arm switching elements on the high potential side all connected to a positive electrode of a second battery that is insulated from one another except for a path including the first battery and the winding, the other ends of the plurality of second upper arm switching elements each connected to one end of the second lower arm switching element on the high potential side corresponding thereto and to the other ends of the windings of a plurality of phases, and the other ends of the plurality of second lower arm switching elements all connected to a negative electrode of the second battery; a control unit that transmits and receives electric power between the first battery and the second battery in order to charge either the first battery or the second battery by setting an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. A control device comprising:

2. The control unit transmits and receives electric power between the first battery and the second battery in order to directly charge either the first battery or the second battery by setting fixed conductive states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. The control device according to claim 1 .

3. The control unit changes a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to perform step-down charging of either the first battery or the second battery. The control device according to claim 1 .

4. The control unit changes a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to boost charge either the first battery or the second battery. The control device according to claim 1 .

5. The control unit is transmission and reception of electric power between the first battery and the second battery by fixing the conduction states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to directly charge either the first battery or the second battery; transmitting and receiving electric power between the first battery and the second battery by changing a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to perform step-down charging of either the first battery or the second battery; In order to boost charge either the first battery or the second battery, a conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element is changed, and power transmission and reception between the first battery and the second battery are switched according to a charging state. The control device according to claim 1 .

6. The control unit is a current command generating unit that generates a current command indicating a current to be set in the AC rotating electric machine; a switching signal generating unit that generates switching signals that switch between an open state and a conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element; a charge control unit that transmits and receives power between the first battery and the second battery in order to charge either the first battery or the second battery by setting an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element. The control device according to claim 1 .

7. The charge control unit sets any one of the plurality of first upper arm switching elements and one of the corresponding second upper arm switching elements to a conductive state, sets any one of the plurality of first lower arm switching elements and one of the plurality of second lower arm switching elements corresponding to these elements to an open state, and changes the conductive states of the remaining elements other than the elements set to the conductive state and the open state.

7. The control device according to claim 6.

8. The current command generating unit generates the current command for controlling the amount of current flowing through the windings so that the amount of current flowing through the windings satisfies a predetermined relationship.

7. The control device according to claim 6.

9. the AC rotating electric machine having a stator provided with the windings of a plurality of phases and a rotor, the windings of the plurality of phases not being connected to each other; The control device according to any one of claims 1 to 8, The power storage drive system is characterized by the above.

10. a first drive unit for driving an AC rotating electric machine having a stator with a multi-phase winding and a rotor, the multi-phase windings not being connected to each other, the first drive unit having a plurality of first upper arm switching elements and a plurality of first lower arm switching elements, all of one ends of the first upper arm switching elements on a high potential side being connected to a positive electrode of a first battery, the other ends of the plurality of first upper arm switching elements being connected to one ends of the corresponding first lower arm switching elements on a high potential side and to one ends of the multi-phase windings, and the other ends of the plurality of first lower arm switching elements being all connected to a negative electrode of the first battery; a second drive unit that drives the AC rotating electric machine, the second drive unit having a plurality of second upper arm switching elements and a plurality of second lower arm switching elements, one ends of the second upper arm switching elements on a high potential side all connected to a positive electrode of a second battery that is insulated from the first battery except for a path including the winding, the other ends of the plurality of second upper arm switching elements are connected to one ends of the second lower arm switching elements on a high potential side corresponding to each of the second lower arm switching elements and to other ends of the windings of a plurality of phases, and the other ends of the plurality of second lower arm switching elements all connected to a negative electrode of the second battery, A control unit sets an open or conductive state of each of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element, thereby transmitting and receiving power between the first battery and the second battery in order to charge either the first battery or the second battery. A control method comprising:

11. The control unit: transmission and reception of electric power between the first battery and the second battery by fixing the conduction states of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to directly charge either the first battery or the second battery; transmitting and receiving electric power between the first battery and the second battery by changing a conduction state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element in order to perform step-down charging of either the first battery or the second battery; In order to boost charge either the first battery or the second battery, a conductive state of any one of the first upper arm switching element, the first lower arm switching element, the second upper arm switching element, and the second lower arm switching element is changed, and power transmission and reception between the first battery and the second battery are switched according to a charging state.

11. The control method according to claim 10.

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