Power supply system

Abstract

A power supply system capable of reducing the processing load of a control device is provided with: 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 line and the negative line; and a control device that, when power is exchanged 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 feed-forward terms based on voltages on the DC sides of the first and second inverters, and a common feedback term for cancelling a difference between a current command and a current for the motor, a duty control is performed on one of the first and second inverters whose duty command is less than a value 1, and an upper arm is fixed on the other of the first and second inverters whose duty command is equal to or greater than the value 1.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power supply system. BACKGROUND

[0002] In the related art, in a charge control device of a power supply device configured of a series-parallel battery system capable of switching a connection mode of a plurality of power storage bodies between series connection and parallel connection, a charge control device provided with a charge control section that performs charge control of the power supply device using an external power supply is proposed (for example, refer to Patent Literature 1). In this case, the charge control section selects a connection mode at the start of charging based on the temperature and the SOC of the power supply device, and controls the charging current for the connection mode of parallel connection using an upper limit value that is larger than an upper limit value for the charging current input to the power supply device in the connection mode of series connection.

[0003] PRIOR ART DOCUMENTS

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2013-81316 SUMMARY

[0005] In a power supply system provided with first and second batteries, a motor having a three-phase coil, first and second positive electrode lines, and first and second inverters connected to the first and second batteries and 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 a control device that controls the first and second inverters, when exchanging electric power between the first and second batteries and the outside via the connector, it is required to reduce the processing load of the control device in selecting which of the first and second inverters to perform duty cycle control. The main object of the power supply system of the present disclosure is to achieve reduction of the processing load of the control device.

[0006] In order to achieve the above main object, the power supply system of the present disclosure employs the following means. The power supply system of the present disclosure is a power supply system provided with first and second batteries, the gist of which is to provide: 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 a control device that, when exchanging electric power between the first and second batteries and the outside via the connector, sets duty cycle commands of the first and second inverters using first and second feedforward terms based on voltages on the direct current side of the first and second inverters, and a common feedback term for eliminating a difference between a current command of the motor and a current, performs duty cycle control on the one of the first and second inverters whose duty cycle command is less than a value of 1, and fixes the upper arm to be on for the one whose duty cycle command is a value of 1 or more. With such control, reduction of the processing load of the control device can be achieved. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the power supply system 10 and the charging power supply pile 80.

[0008] Figure 2 This is a block diagram representing an example of a function block.

[0009] Figure 3 This is an explanatory diagram illustrating an example of FF term mapping.

[0010] Explanation of reference numerals in the attached figures:

[0011] 10 Power supply system, 20 Motor, 22 First inverter, 24 Second inverter, 44 Charging power supply connector, 50 System ECU. Detailed Implementation

[0012] The embodiments (implementations) for carrying out this disclosure will be described with reference to the accompanying drawings. Figure 1 This is a schematic structural diagram of the power supply system 10 and the charging power supply pile 80 according to an embodiment of this disclosure.

[0013] The power system 10 is installed in electric vehicles, hybrid vehicles, and fuel cell vehicles, and includes a battery 12, a motor 20, a first inverter 22, a second inverter 24, a switching circuit 30, a charging power supply circuit 40, and a system ECU 50 (control device). The power system 10 can exchange power between the battery 12 and a charging power supply pile 80 installed at home, a charging station, etc.

[0014] Battery 12 includes first and second batteries 13 and 14. The first and second batteries 13 and 14 are, for example, secondary batteries with a rated voltage of approximately Vs1 (e.g., 400V) and of the same specifications. The positive terminal of the first battery 13 is connected to the first positive line 31, and the negative terminal of the second battery 14 is connected to the 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 equipped with a series relay Rs. By setting the series relay Rs to the ON state, the first and second batteries 13 and 14 are connected in series.

[0015] The motor 20 has, for example, a rotor in which a permanent magnet is embedded in a rotor core, and a stator in which three-phase (U-phase, V-phase, W-phase) coils are wound on a stator core. The first and second inverters 22, 24 have six transistors T11 to T16, T21 to T26 (switching elements), and six diodes D11 to D16, D21 to D26 connected in parallel with the six transistors T11 to T16, T21 to T26, respectively. The transistors T11 to T16, T21 to T26 are arranged in groups of two in a manner such that the source side and the drain side are reversed with respect to the first and second positive lines 31, 32 and the negative line 33, and the connection points of the paired two transistors are connected to one end side and the other end side of the three-phase coils of the motor 20, respectively. The first and second positive lines 31, 32 and the negative line 33 are connected to the first and second capacitors 26, 28, respectively. The transistors T11 to T13, T21 to T23 are sometimes referred to as "upper bridge arms", and the transistors T14 to T16, T24 to T26 are sometimes referred to as "lower bridge arms". The switching circuit 30 has, in addition to the first and second positive lines 31, 32, the negative line 33, the series line 35, and the series relay Rs described above, a parallel line 36 connecting the negative terminal of the first battery 13 to the negative line 33, a first parallel relay Rp1 mounted on the parallel line 36, and a second parallel relay Rp2 mounted on the second positive line 32. The charge power supply circuit 40 has a charge line 42 connected to the first positive line 31 and the negative line 33, and a charge power supply connector 44 connected to the charge line 42 and configured to be connectable to a pile connector 82 of a charge power supply pile 80.

[0016] The signals from various sensors are input to the system ECU 50. As the various sensors, there can be mentioned voltage sensors 13v, 14v that detect the voltages Vbl, Vb2 of the first and second batteries 13, 14, temperature sensors 13t, 14t that detect the temperatures Tb1, Tb2 of the first and second batteries 13, 14, current sensors 20u, 20v, 20w that detect the currents Iu, Iv, Iw flowing through the respective phases of the motor 20, voltage sensors 26v, 28v that detect the voltages VH, VL of the first and second capacitors 26, 28, and current sensors 31i, 32i that detect the currents Ip1, Ip2 flowing through the first and second positive electrode lines 31, 32. The system ECU 50 operates the state of charge SOC1, SOC2 of the first and second batteries 13, 14 on the basis of the on-off states of the series relay Rs and the first and second parallel relays Rp1, Rp2 and the currents Ip1, Ip2 flowing through the first and second positive electrode lines 31, 32, or operates the allowable input and output electric powers Win1, Wout1, Win2, Wout2 on the basis of the state of charge SOC1, SOC2 and the temperatures Tb1, Tb2 of the first and second batteries 13, 14. Control signals are output from the system ECU 50 to the first and second inverters 22, 24, the series relay Rs, and the first and second parallel relays Rp1, Rp2. The system ECU 50 is capable of communicating with the pile ECU 86 of the charging power supply pile 80.

[0017] The charging power supply pile 80 is provided with a pile connector 82 configured to be connectable with the charging power supply connector 44 of the power supply system 10, a power conversion device 84 that converts alternating-current electric power from a power system or the like into direct-current electric power and adjusts the voltage and current to supply to the pile connector 82 side, or that converts direct-current electric power from the pile connector 82 side into alternating-current electric power and adjusts the voltage and current to supply to the power system or the like, and a pile ECU 86. Signals of various sensors are input to the pile ECU 86. Control signals are output from the pile ECU 86 to the power conversion device 84. As described above, the pile ECU 86 is capable of communicating with the system ECU 50. As the charging power supply pile 80, there can be mentioned a first and second voltage pile in which the voltages of electric power (charging power supply electric power) exchanged with the power supply system 10 are the above-described voltage Vs1 and a voltage Vs2 (for example, 800 V) higher than the voltage Vs1, respectively, a third voltage pile in which one of the voltages Vs1, Vs2 can be selectively set as the voltage of the charging power supply electric power, and the like.

[0018] In the power supply system 10, when the charging power supply connector 44 is connected to the pole connector 82, the system ECU 50 selects parallel charging power supply when the voltage of the charging power supply of the charging power supply pole 80 is the voltage Vs1, and selects series charging power supply when the voltage of the charging power supply of the charging power supply pole 80 is the voltage Vs2. In the parallel charging power supply, the first and second batteries 13, 14 are connected in parallel as viewed from the charging power supply connector 44 by setting the series relay Rs to the off state and setting the first and second parallel relays Rp1, Rp2 to the on state, and power is exchanged between the charging power supply pole 80 and the first and second batteries 13, 14. In the parallel charging in the parallel charging power supply, the first battery 13 is charged by the current flowing from the charging power supply connector 44 through the positive line of the charging line 42, the first positive line 31, the first battery 13, the parallel line 36, the negative line 33, the negative line of the charging line 42, and the charging power supply connector 44 in this order. The second battery 14 is charged by the current flowing from the charging power supply 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 power supply connector 44 in this order. At this time, voltage reduction processing based on the first inverter 22 and the motor 20 is performed, or voltage increase processing based on the motor 20 and the second inverter 24 is performed. The parallel power supply is opposite to the parallel charging. As for the series charging power supply, detailed description is omitted.

[0019] The operation of the power supply system 10 of the embodiment, particularly the control of the first and second inverters 22, 24 at the time of parallel charging, is described. Figure 2 is a block diagram showing an example of a functional block of the control of the system ECU 50 over the U phase of the first and second inverters 22, 24 at the time of parallel charging. Also, the control of the V phase and the W phase of the first and second inverters 22, 24 at the time of parallel charging is the same. Also, the control of each phase of the first and second inverters 22, 24 at the time of parallel power supply is the same. As Figure 2 As the functional block of the system ECU 50, the system ECU 50 has a feedforward term setting section 61, a subtraction section 62, a multiplication section 63, a proportional term operation section 64, an integral term operation section 65, an addition section 66, an addition section 67, a subtraction section 68, and upper limit protection sections 69, 70.

[0020] The feedforward term setting unit 61 sets the feedforward terms Du1ff and Du2ff based on voltages VH and VL (the DC side voltages of the first and second inverters 22 and 24) and phase current command Iu*. In the embodiment, the relationship between voltages VH, VL, and phase current command Iu* and feedforward terms Du1ff and Du2ff is obtained by applying voltages VH, VL, and phase current command Iu* in a predetermined FF term mapping through experiments, analysis, etc., to derive the corresponding feedforward terms Du1ff and Du2ff. Figure 3 This is an explanatory diagram illustrating an example of FF term mapping. Figure 3 (A) Figure 3 (B) Figure 3 (C) represents the cases where voltage VH is higher than voltage VL, voltage VH and voltage VL are equal, and voltage VH is lower than voltage VL, respectively. Figure 3 (A) Figure 3 (B) Figure 3 In any case of (C), the larger the phase current command Iu*, the larger the feedforward terms Du1ff and Du2ff are respectively. When the phase current command Iu* is 0, the feedforward terms Du1ff and Du2ff become (VL / VH) and (VH / VL) respectively. Therefore, as Figure 3 As shown in (A), when the voltage VH is higher than the voltage VL, and the phase current command Iu* is 0, the feedforward term Du1ff is less than 1, and Du2ff is more than 1. Figure 3 As shown in (B), when voltages VH and VL are equal, and the phase current command Iu* is 0, the feedforward terms Du1ff and Du2ff both become 1. Figure 3 As shown in (C), when the voltage VH is lower than the voltage VL, and the phase current command Iu* is 0, the feedforward term Du1ff exceeds the value 1, and Du2ff is less than the value 1.

[0021] The subtraction unit 62 operates a difference ΔIu by subtracting the average value of the phase current Iu for a prescribed time, i.e., the average current Iuav, from the phase current command Iu*. The phase current command Iu* and the phase current Iu are values that are positive in the direction from the first inverter 22 to the second inverter 24. The phase current command Iu* is set, for example, based on a required power Ps* that should be supplied from the charging power supply station 80 to the power supply system 10 and a distribution ratio Rd of the first and second batteries 13, 14. The required power Ps* is set, for example, as the sum of required powers Pb1*, Pb2* of the first and second batteries 13, 14 based on the state of charge SOC1, SOC2. The distribution ratio Rd is the ratio of the required power Pb2* to the sum of the required powers Pb1*, Pb2*, and is set, for example, based on the magnitude relationship of the state of charge SOC1, SOC2. The phase current command Iu* is set, for example, as 1 / 3 of the product of the required power Ps* and the distribution ratio Rd. The multiplication unit 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 a carrier frequency fc used in the switching control of the first and second inverters 22, 24. The proportional term operation unit 64 and the integral term operation unit 65 operate 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 the gains Kp, Ki of the proportional term and the integral term, respectively.

[0022] The addition unit 67 operates a temporary duty ratio Du1tmp as the sum of the feedforward term Du1ff and the feedback term Dufb. The subtraction unit 68 operates a temporary duty ratio Du2tmp by subtracting the feedback term Dufb from the feedforward term Du2ff. The upper limit protection unit 69 and the upper limit protection unit 70 set the duty ratio commands Du1*, Du2* by performing upper limit protection of the temporary duty ratios Du1tmp, Du2tmp at a value 1, respectively. The duty ratio commands Du1*, Du2* are the proportions of the on time of the transistors T11, T21 with respect to the sum of the on time of the transistors T11, T21 (upper bridge arms) and the on time of the transistors T14, T24 (lower bridge arms) of the first and second inverters 22, 24, respectively. If the duty ratio command Du1* is set, the duty ratio control is performed on the transistors T11, T14 when the duty ratio command Du1* is less than the value 1, and the on time of the transistor T11 is fixed (the transistor T14 is fixed off) when the duty ratio command Du1* is the value 1. The control of the transistors T21, T24 based on the duty ratio command Du2* is the same.

[0023] Thus, for the U phase, the feedforward terms Duiff, Du2ff are set based on the voltages VH, VL and the phase current command Iu*, and the common feedback term Dufb is calculated in such a manner as to cancel the difference ΔIu between the phase current command Iu* and the average current Iuav (the phase current Iu). Then, the temporary duty ratios Dltmp, D2tmp are obtained by adding and subtracting the feedback term Dufb to and from the feedforward terms Duiff, Du2ff, respectively, and the duty ratio commands Du1*, Du2* are set based on these, and the first and second inverters are controlled further. When the duty ratio command Du1* is less than the value 1 and the duty ratio command Du2* is the value 1, the transistors T11, T14 are duty ratio controlled, and the transistor T21 is turned on fixedly, whereby voltage conversion based on the motor 20 and the first inverter 22 is performed. When the duty ratio command Du1* is the value 1 and the duty ratio command Du2* is less than the value 1, the transistor T11 is turned on fixedly, and the transistors T21, T24 are duty ratio controlled, whereby voltage conversion based on the motor 20 and the second inverter 24 is performed. By using the common feedback term Dufb to select which of the first and second inverters 22, 24 is duty ratio controlled, the processing load of the system ECU 50 can be reduced compared to the case where separate feedback terms are used. The same applies to the V phase and the W phase.

[0024] In the above-described embodiment, the feedforward terms Duiff, Du2ff can also be set based on the voltages VH, VL only, without using the phase current command Iu*. For example, the feedforward terms Duiff, Du2ff can be set to the values (VL / VH), (VH / VL), respectively.

[0025] In the above-described embodiment, the first and second batteries 13, 14 can also be connected in series by setting the first parallel relay Rp1 to the off state and the series relay Rs and the second parallel relay Rp2 to the on state, and the first and second batteries 13, 14 can be connected via the first inverter 22, the motor 20, and the second inverter 24. In this case, the same control as in the above-described lower embodiment can be performed when the first and second batteries 13, 14 are warmed up by exchanging electric power between the first and second batteries 13, 14 via the first inverter 22, the motor 20, and the second inverter 24. In this case, electric power can also be exchanged between the first and second batteries 13, 14 and the outside via the charge power supply connector 44.

[0026] The above describes the manner for implementing the present disclosure using the embodiments, but the present disclosure is not limited to such embodiments, and of course can be implemented in various manners without departing from the spirit of the present disclosure.

[0027] Industrial Applicability

[0028] The present disclosure can be used in the manufacturing industry of power supply systems and the like.

Claims

1. A power supply system including a first battery and a second battery, wherein the power supply system is provided with: a motor having a three-phase coil, a first inverter and a second inverter connected to the first battery and the second battery via a first positive line and a second positive line and a common negative line, and connected to one end side and the other end side of the three-phase coil; a connector connected to the first positive line and the negative line; and a control device that, when exchanging electric power between the first battery and the second battery and an outside via the connector, sets duty command of the first inverter and the second inverter respectively using a first feedforward term and a second feedforward term based on voltage of a direct current side of the first inverter and the second inverter, and a common feedback term for eliminating difference between current command of the motor and current, performs duty control on one of the first inverter and the second inverter whose duty command is less than a value 1, and fixes upper bridge arm on to the other one whose duty command is a value 1 or more. ​

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