Power supply system

Abstract

To reduce a processing load of a control device.SOLUTION: The power supply system includes first and second batteries, a motor having a three-phase coil, first and second inverters connected to the first and second batteries via first and second positive electrode lines and a common negative electrode line and connected to one end side and the other end side of the three-phase coil, a connector connected to the first positive electrode line and the negative electrode line, and first and second feedforward terms based on voltages on DC sides of the first and second inverters and a common feedback term for canceling a difference between a current command and a current of the motor when electric power is exchanged between the first and second batteries and the outside via the connector, and a control device that performs duty control on one of the first and second inverters whose duty command is less than a value 1, and fixes an upper arm of one of the first and second inverters whose duty command is equal to or greater than the value 1 to ON.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to power supply systems. [Background technology]

[0002] A conventional charging control device for a power supply device configured as a series-parallel battery system capable of switching the connection method of multiple power storage units between series and parallel has been proposed, which includes a charging control unit that performs charging control for the power supply device using an external power source (see, for example, Patent Document 1). Here, the charging control unit selects the connection method at the start of charging based on the temperature and SOC of the power supply device, and controls the charging current for the parallel connection method using an upper limit value that is greater than the upper limit value of the charging current input to the power supply device for the series connection method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-81316 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power supply system including first and second batteries, a motor having a three-phase coil, first and second inverters connected to the first and second batteries via first and second positive lines and a common negative line and connected to one end and the other end of the three-phase coil, a connector connected to the first positive line and the negative line, and a control device that controls the first and second inverters, when exchanging power between the first and second batteries and the outside via the connector, it is desired to reduce the processing load of the control device when selecting which of the first and second inverters to duty control.The power supply system of the present disclosure has as its main objective reducing the processing load of the control device. [Means for solving the problem]

[0005] The power supply system of the present disclosure employs the following measures to achieve the above-mentioned primary object. The power supply system of the present disclosure is a power supply system including first and second batteries, a motor having a three-phase coil, first and second inverters connected to the first and second batteries via first and second positive lines and a common negative line and connected to one end and the other end of the three-phase coil, connectors connected to the first positive line and the negative line, and a control device that, when exchanging power between the first and second batteries and the outside via the connectors, sets duty commands for the first and second inverters, respectively, using first and second feedforward terms based on the voltages on the DC sides of the first and second inverters and a common feedback term for canceling out the difference between the current command and the current of the motor, and performs duty control for the first or second inverter whose duty command is less than 1 and fixes the upper arm on for the inverter whose duty command is 1 or greater. This control reduces the processing load of the control device. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of a power supply system 10 and a power charging station 80. FIG. [Figure 2] FIG. 2 is a block diagram showing an example of a functional block. [Figure 3] FIG. 10 is an explanatory diagram showing an example of an FF term map. DETAILED DESCRIPTION OF THE INVENTION

[0007] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of a power supply system 10 and a charging station 80 according to an embodiment of the present disclosure. The power supply system 10 is mounted on an electric vehicle, a hybrid vehicle, or a fuel cell vehicle, and includes a battery 12, a motor 20, first and second inverters 22, 24, a switching circuit 30, a charging circuit 40, and a system ECU 50 (control device). The power supply system 10 is capable of exchanging power between the battery 12 and a charging station 80 installed at a home, a charging station, or the like.

[0008] The battery 12 includes first and second batteries 13, 14 (first and second cells). The first and second batteries 13, 14 are configured as secondary batteries with the same specifications and a rated voltage of, for example, about Vs1 (e.g., 400 V). The positive terminal of the first battery 13 is connected to a first positive line 31, and the negative terminal of the second battery 14 is connected to a negative line 33. The negative terminal of the first battery 13 is connected to the positive terminal of the second battery 14 via a series line 35 to which a series relay Rs is attached. By turning on the series relay Rs, the first and second batteries 13, 14 are connected in series.

[0009] The motor 20 includes, for example, a rotor with a permanent magnet embedded in a rotor core, and a stator with three-phase (U-phase, V-phase, W-phase) coils wound around a stator core. The first and second inverters 22 and 24 include six transistors T11-T16 and T21-T26 (switching elements) and six diodes D11-D16 and D21-D26 connected in parallel to the six transistors T11-T16 and T21-T26, respectively. The transistors T11-T16 and T21-T26 are arranged in pairs, two at a time, on the source and sink sides of the first and second positive lines 31 and 32 and the negative line 33, and the connection points of the two transistors in each pair are connected to one end and the other end of the three-phase coils of the motor 20, respectively. First and second capacitors 26 and 28 are connected to the first and second positive lines 31 and 32 and the negative line 33, respectively. The transistors T11 to T13 and T21 to T23 may be referred to as the "upper arm," and the transistors T14 to T16 and T24 to T26 may be referred to as the "lower arm." In addition to the first and second positive lines 31 and 32, the negative line 33, the series line 35, and the series relay Rs, the switching circuit 30 also includes a parallel line 36 connecting the negative terminal of the first battery 13 and the negative line 33, a first parallel relay Rp1 attached to the parallel line 36, and a second parallel relay Rp2 attached to the second positive line 32. The charging circuit 40 includes a charging line 42 connected to the first positive electrode line 31 and the negative electrode line 33, and a charging connector 44 connected to the charging line 42 and configured to be connectable to a stand connector 82 of the charging stand 80.

[0010] Signals from various sensors are input to the system ECU 50. The various sensors include voltage sensors 13v, 14v and temperature sensors 13t, 14t that detect voltages Vb1, Vb2 and temperatures Tb1, Tb2 of the first and second batteries 13, 14, current sensors 20u, 20v, 20w that detect currents Iu, Iv, Iw flowing through each phase of the motor 20, voltage sensors 26v, 28v that detect voltages VH, VL of the first and second capacitors 26, 28, and current sensors 31i, 32i that detect currents Ip1, Ip2 flowing through the first and second positive electrode lines 31, 32. The system ECU 50 calculates the power storage rates SOC1 and SOC2 of the first and second batteries 13 and 14 based on the on / off states of the series relay Rs and the first and second parallel relays Rp1 and Rp2 and the currents Ip1 and Ip2 flowing through the first and second positive lines 31 and 32, and calculates the allowable input / output powers Win1, Wout1, Win2, and Wout2 based on the power storage rates SOC1 and SOC2 of the first and second batteries 13 and 14 and temperatures Tb1 and Tb2. The system ECU 50 outputs control signals to the first and second inverters 22 and 24, the series relay Rs, and the first and second parallel relays Rp1 and Rp2. The system ECU 50 is capable of communicating with a station ECU 86 of the charging station 80.

[0011] The charging station 80 includes a station connector 82 configured to be connectable to the charging connector 44 of the power supply system 10, a power conversion device 84 that converts AC power from a power grid or the like into DC power and adjusts the voltage and current before supplying the DC power to the station connector 82, or converts DC power from the station connector 82 into AC power and adjusts the voltage and current before supplying the AC power to the power grid, and a station ECU 86. Signals from various sensors are input to the station ECU 86. A control signal is output from the station ECU 86 to the power conversion device 84. As described above, the station ECU 86 is capable of communicating with the system ECU 50. Examples of the charging station 80 include a first voltage station and a second voltage station in which the voltages of the power (charging power) exchanged with the power supply system 10 are the above-mentioned voltage Vs1 and a higher voltage Vs2 (e.g., 800 V), respectively, and a third voltage station in which the voltage of the charging power can be selectively set to either voltage Vs1 or Vs2.

[0012] In power supply system 10, when charging connector 44 and stand connector 82 are connected and the voltage of the charging power supplied from charging stand 80 is voltages Vs1 and Vs2, system ECU 50 selects parallel charging or series charging, respectively. In parallel charging, first and second batteries 13 and 14 are connected in parallel from the perspective of charging connector 44 by turning off series relay Rs and turning on first and second parallel relays Rp1 and Rp2, and power is exchanged between charging stand 80 and first and second batteries 13 and 14. In parallel charging, which is a type of parallel charging, first battery 13 is charged by current that flows from charging connector 44 through the positive line of charging line 42, first positive line 31, first battery 13, parallel line 36, negative line 33, negative line of charging line 42, and charging connector 44 in this order. The second battery 14 is charged by a current that flows in the following order from the charging connector 44 through the positive line of the charging line 42, the first positive line 31, the first inverter 22, the motor 20, the second inverter 24, the second positive line 32, the second battery 14, the negative line 33, the negative line of the charging line 42, and the charging connector 44. At this time, the first inverter 22 and the motor 20 perform a step-down process, and the motor 20 and the second inverter 24 perform a step-up process. In parallel power supply, the process is reversed from that in parallel charging. A detailed description of series charging and power supply will be omitted.

[0013] The operation of the power supply system 10 according to the embodiment will be described, particularly the control of the first and second inverters 22, 24 during parallel charging. FIG. 2 is a block diagram showing an example of functional blocks used by the system ECU 50 to control the U phase of the first and second inverters 22, 24 during parallel charging. The V and W phases of the first and second inverters 22, 24 are controlled in a similar manner during parallel charging. The control of each phase of the first and second inverters 22, 24 during parallel power feeding is also similar. The system ECU 50 includes, as functional blocks shown in FIG. 2, a feedforward term setting unit 61, a subtraction unit 62, a multiplication unit 63, a proportional term calculation unit 64, an integral term calculation unit 65, an addition unit 66, an addition unit 67, a subtraction unit 68, and upper limit guard units 69 and 70.

[0014] The feedforward term setting unit 61 sets the feedforward terms Du1ff and Du2ff based on the voltages VH and VL (voltages on the DC sides of the first and second inverters 22 and 24) and the phase current command Iu*. In this embodiment, the voltages VH and VL and the phase current command Iu* are applied to an FF term map that is determined in advance through experiments, analysis, or the like as the relationship between the voltages VH and VL, the phase current command Iu*, and the feedforward terms Du1ff and Du2ff, and the corresponding feedforward terms Du1ff and Du2ff are derived and obtained. FIG. 3 is an explanatory diagram showing an example of the FF term map. FIGS. 3(A), 3(B), and 3(C) respectively show the cases where the voltage VH is higher than the voltage VL, the voltages VH and VL are equal, and the voltage VH is lower than the voltage VL. In any of the cases of FIGS. 3A, 3B, and 3C, the feedforward terms Du1ff and Du2ff increase and decrease, respectively, as the phase current command Iu* increases, and when the phase current command Iu* is 0, the feedforward terms Du1ff and Du2ff take values ​​(VL / VH) and (VH / VL). Therefore, as shown in FIG. 3A, when the voltage VH is higher than the voltage VL, the feedforward terms Du1ff and Du2ff are less than 1 and exceed 1, respectively, when the phase current command Iu* is 0. As shown in FIG. 3B, when the voltages VH and VL are equal to each other, the feedforward terms Du1ff and Du2ff both take 1 when the phase current command Iu* is 0. As shown in FIG. 3C, when the voltage VH is lower than the voltage VL, the feedforward terms Du1ff and Du2ff are greater than 1 and less than 1, respectively, when the phase current command Iu* is 0.

[0015] The subtraction unit 62 calculates a difference ΔIu by subtracting an average current Iuav, which is the average value of the phase current Iu over a predetermined time, from the phase current command Iu*. The phase current command Iu* and the phase current Iu have positive values ​​in the direction from the first inverter 22 to the second inverter 24. The phase current command Iu* is set, for example, based on the required power Ps* to be supplied from the charging station 80 to the power supply system 10 and the allocation ratio Rd of the first and second batteries 13, 14. The required power Ps* is set, for example, as the sum of the required powers Pb1* and Pb2* of the first and second batteries 13, 14 based on the power storage rates SOC1 and SOC2. The allocation ratio Rd is the ratio of the required power Pb2* to the sum of the required powers Pb1* and Pb2*, and is set, for example, based on the magnitude relationship between the power storage rates SOC1 and SOC2. The phase current command Iu* is set to, for example, 1 / 3 of the product of the required power Ps* and the distribution ratio Rd. A multiplier 63 multiplies the difference ΔIu by a coefficient α. The coefficient α is determined based on the inductance Lu of the U-phase coil and the carrier frequency fc used for switching control of the first and second inverters 22, 24. A proportional term calculator 64 and an integral term calculator 65 calculate a proportional term Dufbp and an integral term Dufbi in the feedback term Dufb by multiplying the product of the difference ΔIu and the coefficient α by proportional and integral term gains Kp and Ki, respectively.

[0016] An adder 67 calculates a temporary duty Du1tmp as the sum of a feedforward term Du1ff and a feedback term Dufb. A subtractor 68 calculates a temporary duty Du2tmp by subtracting the feedback term Dufb from the feedforward term Du2ff. Upper limit guard units 69 and 70 set duty commands Du1* and Du2* by upper limiting the temporary duties Du1tmp and Du2tmp with a value of 1, respectively. Duty commands Du1* and Du2* represent the ratio of the on-time of transistors T11 and T21 (upper arms) of the first and second inverters 22 and 24 to the sum of the on-time of transistors T11 and T21 (upper arms) and the on-time of transistors T14 and T24 (lower arms), respectively. When duty command Du1* is set, transistors T11 and T14 are duty controlled when duty command Du1* is less than 1, and transistor T11 is fixed on (transistor T14 is fixed off) when duty command Du1* is 1. The same applies to control of transistors T21 and T24 based on duty command Du2*.

[0017] In this way, for the U phase, feedforward terms Du1ff and Du2ff are set based on voltages VH and VL and phase current command Iu*, and a common feedback term Dufb is calculated so that the difference ΔIu between the phase current command Iu* and the average current Iuav (phase current Iu) is canceled. Next, duty commands Du1* and Du2* are set based on temporary duties D1tmp and D2tmp, which are obtained by adding or subtracting feedback term Dufb to or from feedforward terms Du1ff and Du2ff, respectively, to control the first and second inverters. When duty command Du1* is less than 1 and duty command Du2* is 1, transistors T11 and T14 are duty-controlled and transistor T21 is fixed on, thereby performing voltage conversion by motor 20 and first inverter 22. When duty command Du1* is 1 and duty command Du2* is less than 1, transistor T11 is fixed on and transistors T21 and T24 are duty controlled, thereby performing voltage conversion by motor 20 and second inverter 24. By using a common feedback term Dufb to select which of first and second inverters 22 and 24 is to be duty controlled, the processing load on system ECU 50 can be reduced compared to when individual feedback terms are used. The same applies to the V-phase and W-phase.

[0018] In the above-described embodiment, the feedforward terms Du1ff and Du2ff may be set based only on the voltages VH and VL without using the phase current command Iu*. For example, the feedforward terms Du1ff and Du2ff may be set to the values ​​(VL / VH) and (VH / VL), respectively.

[0019] In the above-described embodiment, the first and second batteries 13, 14 may be connected in series by turning the first parallel relay Rp1 off and the series relay Rs and the second parallel relay Rp2 on, and the first and second batteries 13, 14 may be connected to the second battery 14 via the first inverter 22, the motor 20, and the second inverter 24. In this case, control similar to that in the above-described embodiment may be performed when power is exchanged between the first and second batteries 13, 14 and the second battery 14 via the first inverter 22, the motor 20, and the second inverter 24 to raise the temperatures of the first and second batteries 13, 14. In this case, power may also be exchanged between the first and second batteries 13, 14 and the outside via the power supply connector 44.

[0020] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0021] The present disclosure is applicable to the power supply system manufacturing industry and the like. [Explanation of symbols]

[0022] 10 power supply system, 20 motor, 22 first inverter, 24 second inverter, 44 charging connector, 50 system ECU.

Claims

[Claim 1] A power supply system including first and second batteries, a motor having a three-phase coil; first and second inverters connected to the first and second batteries via first and second positive lines and a common negative line, and connected to one end and the other end of the three-phase coil; a connector connected to the first positive line and the negative line; a control device that, when exchanging power between the first and second batteries and the outside via the connector, sets duty commands for the first and second inverters, respectively, using first and second feedforward terms based on the voltages on the DC sides of the first and second inverters and a common feedback term for canceling out a difference between a current command and the current of the motor, and performs duty control for one of the first and second inverters whose duty command is less than 1, and fixes an upper arm on for the one whose duty command is 1 or more; A power supply system comprising:

Images