JP6495412B1 - Power system - Google Patents

Abstract

To provide a power supply system capable of making the direction of an inrush current that can occur at the time of starting a voltage converter provided between two batteries constant.
A power supply system S includes a first circuit 1 having a high output type first battery 10, a second circuit 2 having a high capacity type second battery 20, a voltage converter 3, and a primary side. A voltage sensor 15, a secondary side voltage sensor 25, and an ECU 5 that controls the voltage converter 3, and the second circuit 2 is connected to both ends of the series connection body of the upper arm 32 and the lower arm 31, One circuit 1 is connected to the lower arm 31 via a reactor L. The ECU 5 sets the primary side voltage sensor value V1_sens, the secondary side voltage sensor value V2_sens, the maximum error value ε1 of the primary side voltage sensor 15 and the maximum error value ε2 of the secondary side voltage sensor 25. Based on this, the initial duty ratios γ1 and γ2 of the upper arm 32 and the lower arm 31 when the voltage converter 3 is started are set.
[Selection] Figure 1

Description

  The present invention relates to a power supply system. More specifically, the present invention relates to a power supply system including two batteries and a voltage converter provided between these batteries.

  2. Description of the Related Art In recent years, a vehicle power supply system has been proposed in which two batteries having different characteristics are connected by a converter and power can be interchanged between these power supplies (see, for example, Patent Document 1). In such a power supply system including two batteries, since there is a considerable potential difference between the two batteries, the converter needs to be controlled so as not to generate an inrush current due to the potential difference.

  In Patent Document 1, a drive device that generates a driving force for driving a vehicle, a first battery, a first converter provided between the first battery and the drive device, and the first battery are input to the first converter. A first sensor for detecting a first voltage, a second battery, a second converter provided between the second battery and the driving device, and a second voltage input from the second battery to the second converter. In the power supply system including the second sensor to be detected, a procedure for executing the upper arm on control of the first converter so that no inrush current is generated is shown.

  In the power supply system of Patent Document 1, the upper arm on control refers to maintaining the upper and lower arms of the first converter in a conductive state and a stopped state, respectively, in order to reduce switching loss due to the first converter. For example, when such upper arm ON control is executed in a state where the second voltage is higher than the first voltage, an inrush current may flow from the second battery to the first battery due to this potential difference. Therefore, the execution of the upper arm on control is permitted when the first voltage is higher than the second voltage.

  In addition, the detection values of the first sensor and the second sensor are used to determine whether or not the upper arm ON control can be executed, but there is an error in these sensors. Therefore, in the power supply system described in Patent Document 1, in order to prevent the inrush current as described above from occurring reliably, the first voltage is assumed assuming that the sensor error of the first sensor and the second sensor is the worst condition. And the second voltage are compared to determine whether or not the upper arm on control can be executed.

Japanese Patent Laid-Open No. 2006-59124

  FIG. 4 is a diagram schematically illustrating a configuration of a conventional power supply system 100 including two batteries. The power supply system 100 includes a first battery 101, a second battery 102 having an output voltage higher than that of the first battery 101, and a voltage converter 103 provided between the batteries 101 and 102. The voltage converter 103 is a so-called bi-directional DCDC converter, and operates as a step-up chopper to boost the output of the first battery 101 and supply it to the second battery 102 side or operate as a step-down chopper. The output of the battery 102 is stepped down and supplied to the first battery 101 side. When the voltage converter 103 is operated as a step-up chopper, the switching element of the upper arm 105 and the switching element of the lower arm 104 are turned on / off so as to be complementary to each other.

  FIG. 5 is a time chart showing an example of control of the switching elements of the upper arm 105 and the lower arm 104 when the voltage converter 103 is activated. More specifically, a theoretical duty ratio (1-V1 / V2) in which the on-duty ratio of the switching element of the lower arm 104 at the time of startup is determined by the voltage V1 on the first battery 101 side and the voltage V2 on the second battery 102 side. It is a figure which shows the change of the various electric current when it is lower than. FIG. 5 shows a current ID1 that flows through the diode of the lower arm 104, a current IQ2 that flows through the switching element of the upper arm 105, and a current IL that flows through the reactor in order from the lower stage.

  As shown in FIG. 5, in the power supply system 100, a large inrush current may flow to the first battery 101 if the on-duty ratio of the lower arm 104 when the voltage converter 103 is started is smaller than the theoretical duty ratio. Although not shown, if the on-duty ratio of the lower arm 104 is larger than the theoretical duty ratio, a large inrush current may flow to the second battery 102 in some cases.

  As described above, in the power supply system 100 in which the voltage converter 103 is provided between the two batteries 101 and 102, even when there is a difference between the on-duty ratio and the theoretical duty ratio when the voltage converter 103 is started, There is a risk of current generation. However, in the power supply system of Patent Document 1, although attention is paid to the inrush current generated at the start of the upper arm on control, the inrush current generated due to the deviation of the on-duty ratio at the start-up is not sufficiently studied.

  As described above, since the inrush current due to the deviation of the on-duty ratio at the time of start-up can flow to both the first battery 101 side and the second battery 102 side, some countermeasure is taken against the inrush current in any direction. It is necessary to take.

  An object of this invention is to provide the power supply system which can make constant the direction of the inrush current which can be generated at the time of starting of the voltage converter provided between two electrical storage devices.

  (1) A power supply system (for example, power supply system S described later) of the present invention includes a first circuit (for example, first circuit 1 described later) having a first battery (for example, first battery 10 described later), A second circuit (for example, a second circuit 2 described later) having two capacitors (for example, a second battery 20 described later), an upper arm (for example, an upper arm 32 described later), and a lower arm (for example, a lower arm described later) 31), and a voltage converter (for example, voltage converter 3 to be described later) that has a reactor (for example, a reactor L to be described later) and converts a voltage between the first circuit and the second circuit, First voltage acquisition means (for example, a primary side voltage sensor 15 described later) for acquiring a value of a first voltage that is a voltage of the first circuit, and a value of a second voltage that is a voltage of the second circuit. Second voltage acquisition means (for example, a secondary side voltage sensor described later) 25) and a control device (for example, ECU 5 described later) for controlling the voltage converter, and the second circuit is connected to both ends of a series connection body of the upper arm and the lower arm, One circuit is connected to the lower arm through the reactor, and the control device includes a first voltage acquisition value (for example, a primary voltage sensor value V1_sens described later) by the first voltage acquisition unit, and the first voltage acquisition unit. A second voltage acquisition value (for example, a secondary side voltage sensor value V2_sens described later) by the two voltage acquisition means and an acquisition error value (for example, a constant described later) of the first voltage by the first voltage acquisition means set in advance. ε1) and a predetermined error acquisition value of the second voltage by the second voltage acquisition means (for example, a constant ε2 described later), and the upper arm at the time of activation of the voltage converter and Duty ratio of the serial lower arm (e.g., the initial duty ratio γ1 below, .gamma.2) and sets the.

(2) In this case, the first voltage acquisition value is V1_sens, the predetermined maximum value of the first voltage acquisition error by the first voltage acquisition means is ε1, and the second voltage acquisition value is V2_sens. The predetermined maximum value of the second voltage acquisition error by the second voltage acquisition means is ε2, and the control device sets the duty ratio γ1 of the lower arm when the voltage converter is activated to the following formula ( It is preferable to set based on 1).

(3) In this case, it is preferable that the control device sets the duty ratio γ2 of the upper arm based on the following equation (2) when the voltage converter is activated.

  (4) In this case, it is preferable that the larger one of the first capacitor and the second capacitor can be charged by an external charger (for example, an external charger C described later) until it is fully charged.

  (5) In this case, the second capacitor has a larger capacity than the first capacitor, and the second circuit has an external charger (for example, an external charger described later) for fully charging the second capacitor. It is preferable that a connecting portion (for example, an external positive terminal 23 and an external negative terminal 24 described later) to be connected is provided.

  (1) In the power supply system of the present invention, a voltage converter for converting a voltage between the first circuit having the first capacitor and the second circuit having the second capacitor is provided. In such a power supply system, the duty ratio (hereinafter also referred to as “initial duty ratio”) of the upper arm and the lower arm at the time of starting up the voltage converter is based on a theoretical duty ratio determined from the actual first voltage and second voltage. If it shifts, an inrush current may flow to either the first capacitor side or the second capacitor side. In addition, the first and second voltage acquisition values acquired by the first and second voltage acquisition means include not only errors, but the initial duty ratio is set to the theoretical duty so that no inrush current flows in any direction. It is difficult to match the ratio. Therefore, the control device of the present invention provides a first voltage acquisition value by the first voltage acquisition unit, a second voltage acquisition value by the second voltage acquisition unit, and an error in acquiring the first voltage by a predetermined first voltage acquisition unit. An initial duty ratio is set based on the value and a predetermined error acquisition value of the second voltage by the second voltage acquisition means. According to the power supply system of the present invention, in addition to the first and second voltage acquisition values, the initial duty ratio is set using these acquisition error values whose values are determined in advance. Even if the two-voltage acquisition value is deviated from the true value within the range of the acquisition error value, the initial duty ratio can always be set to be smaller or larger than the theoretical duty ratio. Therefore, according to the power supply system of the present invention, the direction of the inrush current that can be generated when starting up the voltage converter can be limited to only one of the first capacitor side and the second capacitor side. It is sufficient to apply to only one of them.

  (2) In the power supply system of the present invention, using the predetermined maximum value ε1 of the first voltage acquisition error and the maximum value ε2 of the second voltage acquisition error, the initial value of the lower arm according to the above equation (1) is used. A duty ratio γ1 is set. According to the power supply system of the present invention, by setting the initial duty ratio γ1 according to the above equation (1), the first voltage acquisition value V1_sens and the second voltage acquisition value V2_sens have maximum error values ε1, ε2 with respect to the true value. However, the initial duty ratio γ1 can always be set smaller than the theoretical duty ratio. For this reason, since the direction of the inrush current generated when starting up the voltage converter can always be limited from the second capacitor side to the first capacitor side, it is sufficient to take measures against the inrush current only on the first capacitor side. .

  (3) According to the power supply system of the present invention, by setting the initial duty ratio γ2 in accordance with the above equation (2), the voltage converter is started while the lower arm and the upper arm are complementarily turned on / off. The direction of the inrush current sometimes generated can always be limited from the second capacitor side to the first capacitor side.

  (4) According to the power supply system of the present invention, the larger one of the first capacitor and the second capacitor can be charged until it is fully charged by the external charger. Therefore, according to the vehicle equipped with the power supply system of the present invention, the travel distance can be increased. By the way, when the power supply system is started after the capacitor is fully charged by the external charger, the inrush current generated when the voltage converter is started flows into the capacitor that is already fully charged, and the capacitor deteriorates. There is a risk. On the other hand, in the power supply system of the present invention, the direction of the inrush current that can be generated when the voltage converter is started as described above can be limited to only one of the first capacitor side and the second capacitor side. Therefore, in the power supply system of the present invention, the inrush current generated at the time of starting the voltage converter is prevented from flowing to the one of the first and second capacitors that can be fully charged by the external charger. Deterioration of the battery can be suppressed while increasing the distance.

  (5) As described above, according to the power supply system of the present invention, the direction of the inrush current generated when starting up the voltage converter can always be limited from the second capacitor side to the first capacitor side. Further, in the power supply system of the present invention, the capacity of the second capacitor is made larger than that of the first capacitor, and an external charger for fully charging the second capacitor is provided in the second circuit provided with the second capacitor. A connecting portion to be connected is provided. Thereby, after connecting an external battery charger to a connection part and making a 2nd battery full charge, when starting a power supply system, it can prevent that an inrush current flows into the 2nd battery fully charged. Therefore, deterioration of the second capacitor can be suppressed while the second capacitor is fully charged.

It is a figure which shows the structure of the vehicle and external charger which mount the power supply system which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure which starts a voltage converter and performs feedback control using the output of a primary side current sensor. It is a figure which shows the specific example of the change of the reactor current at the time of starting of a voltage converter. It is a figure which shows typically the structure of the conventional power supply system provided with two power supplies. It is a time chart which shows an example of control of the switching element of an upper arm and a lower arm at the time of starting of a voltage converter.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a vehicle V equipped with a power supply system S according to the present embodiment and an external charger C for the vehicle. In the present embodiment, a so-called electric vehicle including two batteries and a voltage converter provided between these batteries will be described as an example of the vehicle V, but the present invention is not limited to this. The power supply system according to the present invention is not limited to an electric vehicle, and any hybrid vehicle or fuel cell vehicle may be used as long as it includes two or more batteries and a voltage converter provided between these batteries. It can also be applied to vehicles.

  The external charger C is a quick charger installed in a charging station, a commercial facility, a public facility, or the like, which is a facility mainly for charging. The external charger C outputs a direct current having a predetermined charging voltage to the power supply system S of the vehicle V via a charging cable. Both the positive and negative terminals of the external charger C are connected to a charging connector provided at the tip of the charging cable to an inlet (not shown) of the vehicle V. Connected to the external negative terminal 24. Further, when the external charger C is connected to both terminals 23 and 24 of the power supply system S, power can be supplied from the external charger C to the power supply system S.

  The vehicle V includes a power supply system S, a motor M, and drive wheels W. The motor M mainly generates power for the vehicle V to travel. The motor M is connected to the drive wheel W. Torque generated by the motor M by supplying electric power from the power supply system S to the motor M is transmitted to the drive wheels W via a power transmission mechanism (not shown), and the drive wheels W are rotated to drive the vehicle V. The motor M acts as a generator when the vehicle V is decelerated and regenerated. The electric power generated by the motor M is charged into a later-described first battery 10 and second battery 20 included in the power supply system S.

  The power supply system S includes a first circuit 1, a second circuit 2, a voltage converter 3 provided between the first circuit 1 and the second circuit 2, an inverter 4, a voltage converter 3 and an inverter 4. An electronic control unit 5 (hereinafter abbreviated as “ECU (Electrical Control Unit) 5”).

  The first circuit 1 includes a first battery 10 that outputs direct current, a positive electrode and a negative electrode of the first battery 10, a primary-side positive terminal 11 and a primary-side negative terminal 12 of the voltage converter 3 (hereinafter, these are summarized. A first positive power line 1p and a first negative power line 1n (hereinafter collectively referred to as “first power lines 1p, 1n”) connected to the “primary side terminals 11, 12”, and the first A contactor (not shown) that electrically connects or disconnects the battery 10 and the first power lines 1p, 1n is provided.

  The first battery 10 is a secondary battery capable of both discharging for converting chemical energy into electric energy and charging for converting electric energy into chemical energy. Hereinafter, as the first battery 10, a case where a so-called lithium ion storage battery that charges and discharges by moving lithium ions between electrodes will be described, but the present invention is not limited thereto.

  The first power lines 1p and 1n detect a voltage V1 (hereinafter also referred to as “primary side voltage V1”) between the primary side terminals 11 and 12 of the voltage converter 3 and a signal corresponding to the detected value. A primary side voltage sensor 10 for transmitting to the ECU 5 is provided. Hereinafter, the output of the primary side voltage sensor 15 is expressed as a primary side voltage sensor value V1_sens. The primary side voltage V1 is basically equal to the output voltage of the first battery 10.

  Further, the first positive power line 1p detects a current I1 (hereinafter also referred to as “primary side current I1”) flowing through the first positive power line 1p, and transmits a signal corresponding to the detected value to the ECU 5. A current sensor 16 is provided.

  The second circuit 2 includes a second battery 20 that outputs a direct current, a positive electrode and a negative electrode of the second battery 20, a secondary positive electrode terminal 21 and a secondary negative electrode terminal 22 of the voltage converter 3 (hereinafter, these are summarized. The second positive power line 2p and the second negative power line 2n (hereinafter collectively referred to as "second power lines 2p, 2n") connected to the "secondary terminals 21, 22"), The external positive terminal 23 and the external negative terminal 24 provided on the two power lines 2p and 2n, respectively, and a contactor (not shown) that electrically connects or disconnects the second battery 20 and the second power lines 2p and 2n.

  During external charging by the external charger C, the positive output terminal and the negative output terminal are connected to the external positive terminal 23 and the external negative terminal 24. Thereby, the second battery 20 is charged by the external charger C. Since the voltage converter 3 is provided between the first battery 10 and the external charger C, basically, the first battery 10 cannot be charged by the external charger C. However, at the time of external charging, the voltage converter 3 may be driven and power from the external charger C may be supplied to the first battery 10 by using a step-down function described later to charge the first battery 10. However, when the second battery 20 is fully charged by the external charger C, the first battery 10 is externally charged so that the power generated by the motor M during the deceleration regeneration of the vehicle V can be collected by the first battery 10. It is preferable that the battery is not fully charged.

  The second battery 20 is a secondary battery capable of both discharging for converting chemical energy into electric energy and charging for converting electric energy into chemical energy. Hereinafter, as the second battery 20, a case where a so-called lithium ion storage battery that performs charging and discharging by moving lithium ions between electrodes will be described, but the present invention is not limited thereto. In the following, a case where the second battery 20 having a voltage at full charge lower than the charge voltage of the external charger C is used as the second battery 20 so that the second battery 20 can be fully charged by the external charger C will be described. .

  The second power lines 2p and 2n detect a voltage V2 between the secondary terminals 21 and 22 of the voltage converter 3 (hereinafter also referred to as “secondary voltage V2”), and send a signal corresponding to the detected value. A secondary side voltage sensor 25 that transmits to the ECU 5 is provided. Hereinafter, the output of the secondary side voltage sensor 25 is expressed as a secondary side voltage sensor value V2_sens. The secondary side voltage V2 is basically equal to the output voltage of the second battery 20.

  Here, the difference between the first battery 10 and the second battery 20 will be described. First, the output voltage of the first battery 10 is lower than the output voltage of the second battery 20. Therefore, the primary side voltage V1 is basically lower than the secondary side voltage V2 (V1 <V2). The second battery 20 has a lower output weight density than the first battery 10, but a higher energy weight density. That is, the second battery 20 is superior to the first battery 10 in terms of energy weight density, and the first battery 10 is superior to the second battery 20 in terms of output weight density. The energy weight density is the amount of power per unit weight [Wh / kg], and the output weight density is the power per unit weight [W / kg]. Therefore, the second battery 20 having an excellent energy weight density is a high-capacity capacitor mainly for high capacity, and the first battery 10 having an excellent output weight density is a high battery mainly for high output. This is an output type capacitor.

  The inverter 4 is a PWM inverter by pulse width modulation including a bridge circuit configured by bridge-connecting a plurality of switching elements (for example, IGBTs), and has a function of converting DC power and AC power. The inverter 4 is connected to the second power lines 2p and 2n on the DC input / output side, and is connected to the U-phase, V-phase, and W-phase coils of the motor M on the AC input / output side.

  The inverter 4 includes a high-side U-phase switching element and a low-side U-phase switching element connected to the U-phase of the motor M, and a high-side V-phase switching element and a low-side V-phase switching element connected to the V-phase of the motor M. A high-side W-phase switching element and a low-side W-phase switching element connected to the W-phase of the motor M are bridge-connected for each phase. The inverter 4 turns on / off the switching elements of each phase in accordance with a gate drive signal generated at a predetermined timing from the gate drive circuit of the ECU 5, thereby converting the DC power supplied from the second power lines 2p and 2n to AC. The power is converted into electric power and supplied to the motor M, or the AC power supplied from the motor M is converted into DC power and supplied to the second power lines 2p and 2n.

  The voltage converter 3 includes a lower arm 31 having a transistor Q1 as a switching element, an upper arm 32 having a transistor Q2 as a switching element, a reactor L, a primary side smoothing capacitor C1, and a secondary side smoothing capacitor C2. And a so-called bidirectional DCDC converter configured by combining the primary side terminals 11 and 12 and the secondary side terminals 21 and 22.

  The emitter of the transistor Q1 of the lower arm 31 is connected to the secondary negative terminal 22 and the primary negative terminal 12, and the collector of the transistor Q2 of the upper arm 32 is connected to the secondary positive terminal 21. The collector of the transistor Q1 and the emitter of the transistor Q2 are connected at a connection midpoint 33. That is, the second power lines 2p and 2n of the second circuit 2 are connected to both ends of the series connection body of the lower arm 31 and the upper arm 32. Anti-parallel diodes D1 and D2 are connected to the transistors Q1 and Q2, respectively. The forward direction of the antiparallel diode D1 is a direction from the connection middle point 33 toward the secondary positive terminal 21, and the forward direction of the antiparallel diode D2 is a direction from the secondary negative terminal 22 to the connection middle point 33. is there.

  As these transistors Q1 and Q2, a power bipolar transistor, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or the like is used. The switching operation of the transistor Q1 is controlled according to a gate drive signal P1 generated at a predetermined timing from the gate drive circuit of the ECU 5. The switching operation of the transistor Q2 is controlled according to a gate drive signal P2 generated at a predetermined timing from the gate drive circuit of the ECU 5.

  The reactor L is connected between the primary side positive terminal 11 and the connection middle point 33. That is, the first power lines 1p and 1n of the first circuit 1 are connected to the lower arm 31 via the reactor L. The primary side smoothing capacitor C <b> 1 is connected between the primary side positive terminal 11 and the primary side negative terminal 12. The secondary side smoothing capacitor C <b> 2 is connected between the secondary side positive terminal 21 and the secondary side negative terminal 22.

  The voltage converter 3 configured as described above boosts the voltage from the primary side terminals 11 and 12 to the secondary side terminals 21 and 22 by operating as a boost chopper by the gate drive signals P1 and P2 from the ECU 5. And a step-down function for stepping down and outputting a voltage from the secondary side terminals 21 and 22 to the primary side terminals 11 and 12 by operating as a step-down chopper by the gate drive signals P1 and P2 from the ECU 5. .

  The ECU 5 is a microcomputer that is responsible for running control of the vehicle V, more specifically, for controlling the voltage converter 3 and the inverter 4. In addition, the ECU 5 controls the voltage converter 3 so that the characteristics of the first battery 10 that is a high output type and the second battery 20 that is a high capacity type are utilized. More specifically, the ECU 5 covers the required power in the motor M from the second battery 20 that is basically a high capacity type. In addition, when the second battery 20 cannot cover all of the required power in the motor M, for example, during high-load operation, the ECU 5 is insufficient to cover this shortage with the first battery 10 that is a high output type. The voltage converter 3 is controlled by feedback control using the output of the primary side current sensor 16 so that a current having a magnitude corresponding to the minute flows from the first battery 10 toward the voltage converter 3. The ECU 5 includes a RAM 5a as a storage medium. In the RAM 5a, a constant ε1, which will be described later, which is the maximum value of the detection error of the primary voltage sensor 15 specified by performing a test on the primary voltage sensor 15 in advance, and a secondary voltage sensor in advance. A constant ε2, which will be described later, which is the maximum value of the detection error of the secondary side voltage sensor 25 specified by performing a test on 25, is stored.

  FIG. 2 is a flowchart showing a procedure for starting the voltage converter 3 in the ECU 5 and executing feedback control using the output of the primary side current sensor 16. The flowchart of FIG. 2 is executed in the ECU 5 in response to a start request for the voltage converter 3 in a state where the voltage converter 3 is stopped, that is, in a state where the transistors Q1 and Q2 are turned off.

  First, in S1, the ECU 5 acquires the primary voltage sensor value V1_sens and the secondary voltage sensor value V2_sens immediately before starting the voltage converter 3.

In S2, the ECU 5 sets initial duty ratios γ1 [%] and γ2 [%], which are duty ratios of the transistor Q1 of the lower arm 31 and the transistor Q2 of the upper arm 32 when the voltage converter 3 is started. More specifically, the ECU 5 calculates the following equation (3-1) based on the sensor values V1_sens and V2_sens acquired in S1 and positive constants ε1 and ε2 that are slightly larger than the predetermined zero. ) And (3-2), the initial duty ratio γ1 of the transistor Q1 and the initial duty ratio γ2 of the transistor Q2 are set. Here, the initial duty ratio γ1 of the transistor Q1 is γ1 = t1 / T × 100 when the duty cycle is T [sec] and the period during which the transistor Q1 is turned on during the duty cycle T is t1 [sec]. It is represented by The initial duty ratio Q2 of the transistor Q2 is expressed by γ2 = t2 / T × 100, where t2 [sec] is a period during which the transistor Q2 is turned on during the duty cycle T.

  In the above formulas (3-1) and (3-2), the constant ε1 is the maximum value of the detection error of the primary side voltage sensor 15 and is a value unique to the primary side voltage sensor 15. The constant ε2 is the maximum value of the detection error of the secondary side voltage sensor 25 and is a value unique to the secondary side voltage sensor 25. That is, if the true value of the primary side voltage is expressed as V1, the sensor value V1_sens exists in the range of V1−ε1 to V1 + ε1 (V1−ε1 ≦ V1_sens ≦ V1 + ε1). When the true value of the secondary side voltage is expressed as V2, the sensor value V2_sens exists in the range of V2−ε2 to V2 + ε2 (V2−ε2 ≦ V2_sens ≦ V2 + ε2). In the above calculation, values stored in advance in the RAM 5a of the ECU 5 are used for the constants ε1, ε2.

  In S3, the ECU 3 complementarily drives the transistor Q1 of the lower arm 31 and the transistor Q2 of the upper arm 32 under the initial duty ratios γ1 and γ2 set in S2. Here, the complementary driving of the transistors Q1 and Q2 specifically means that the transistor Q1 is turned on / off under the initial duty ratio γ1, the transistor Q2 is turned off while the transistor Q1 is turned on, and This means that the transistor Q2 is turned on while the transistor Q1 is turned off.

  In S4, it is determined whether or not a predetermined time (for example, several tens [ms]) has elapsed since the activation of the voltage converter 3 was started. If the determination in S4 is NO, the process returns to S3 and the transistors Q1 and Q2 are complementarily driven under the initial duty ratios γ1 and γ2 until a predetermined time elapses. If the determination in S4 is YES, the process moves to S5.

  In S <b> 5, the ECU 5 starts feedback control of the voltage converter 3 using the output of the primary side current sensor 16. More specifically, the ECU 5 sets a target value for the output current from the first battery 10 based on the required power in the motor M, and the detected value of the primary side current sensor 16 matches this target value. The duty ratios for the transistors Q1 and Q2 are set to the transistors Q1 and Q2, and the transistors Q1 and Q2 are turned on / off so that this setting is realized.

  Here, the technical significance of driving the voltage converter 3 under the initial duty ratios γ1 and γ2 set as described above when the voltage converter 3 is started will be described.

  FIG. 3 is a diagram illustrating a specific example of a change in the reactor current when the voltage converter 3 is started. In FIG. 3, the initial duty ratio γ1 of the transistor Q1 at the time of start-up is a theoretical duty ratio (1−V1 / V2) determined according to the true value V1 of the primary side voltage and the true value V2 of the secondary side voltage. The case is indicated by a solid line. FIG. 3 shows a case where the initial duty ratio γ1 is larger than the theoretical duty ratio by a broken line, and a case where the initial duty ratio γ1 is smaller than the theoretical duty ratio is shown by a one-dot chain line. In FIG. 3, one duty cycle is from time t1 to time t3.

  As shown by the solid line in FIG. 3, when the transistor Q1 is turned off at time t1, the reactor current IL starts to increase in the positive direction (from the first battery 10 side to the second battery 20 side). Thereafter, when the transistor Q1 is turned off from the on state at the time t2 and the transistor Q2 is turned on from the off state, the reactor current IL starts to decrease and reaches the maximum in the negative direction at the time t3. Here, if the initial duty ratio of the transistor Q1 is accurately set to the theoretical duty ratio, the maximum value in the positive direction and the maximum value in the negative direction of the reactor current IL coincide with each other. 2 No inrush current is generated in any direction on the battery 20 side.

  On the other hand, when the initial duty ratio γ1 becomes larger than the theoretical duty ratio, excessive boosting occurs, and the reactor current IL increases in the positive direction at every duty cycle, and from the first battery 10 side to the second battery 20. Inrush current is generated to the side. On the other hand, when the initial duty ratio γ1 is smaller than the theoretical duty ratio, the boost is under-boosted, and the reactor current IL increases in the negative direction at every duty cycle, from the second battery 20 side to the first battery 10 side. Inrush current is generated. As described above, since the sensor values V1_sens and V2_sens change within the error range with respect to the true values V1 and V2, the initial duty ratio γ1 is obtained by inputting the sensor values V1_sens and V2_sens into an equation for determining the theoretical duty ratio. Is set (that is, γ1 = 1−V1_sens / V2_sens), an excessive boosting and an underboosting can occur.

  On the other hand, as described with reference to FIG. 1, the high-capacity second battery 20 can be fully charged by the external charger C so that the characteristics are utilized. The first battery 10 that is a high output type is basically not fully charged so that regenerative power can be received. Therefore, if the inrush current flows into the second battery 20 that is excessively boosted and has a relatively high possibility of being fully charged, the deterioration of the second battery 20 may be promoted. Therefore, it is preferable that the inrush current generated when starting up the voltage converter 3 flows to the first battery 10 side.

  Therefore, the ECU 5 determines the initial duty ratio γ1 when the voltage converter 3 is activated by the above equation (3-1). In other words, the actual primary side voltage and the secondary side voltage can exist within the range of ± ε1, ± ε2 with respect to the sensor values V1_sens and V2_sens actually acquired by the sensors 15 and 25. The voltage is estimated with the largest possible value within the error range, and the secondary side voltage is estimated with the smallest possible value within the error range. By setting the initial duty ratio γ1 to the maximum within the error range, the sensor value V1_sens, The voltage converter 3 can be started up so that the voltage is always under-boosted no matter how the V2_sens changes within the error range. As a result, when the voltage converter 3 is started, an inrush current flows from the second battery 20 side to the first battery 10 side. However, the first battery 10 is not fully charged and has room to accept the inrush current. Therefore, both the first battery 10 and the second battery 20 can suppress deterioration.

The power supply system S of the present embodiment has the following effects.
(1) In the power supply system S, the voltage converter 3 that converts the voltage between the first circuit 1 having the first battery 10 and the second circuit 20 having the second battery 20 is provided. The ECU 5 compares the primary side voltage sensor value V1_sens from the primary side voltage sensor 15, the secondary side voltage sensor value V2_sens from the secondary side voltage sensor 25, and the primary side voltage sensor 15 acquisition error of the primary side voltage sensor 15. Based on the maximum value ε1 and the maximum value ε2 of the secondary side voltage acquisition error by the secondary side voltage sensor 25, the initial duty ratios γ1, γ2 are set. According to the power supply system S, in addition to the primary side voltage sensor value V1_sens and the secondary side voltage sensor value V2_sens, by setting the initial duty ratios γ1 and γ2 using the maximum values ε1 and ε2 of these errors, Even if the primary side voltage sensor value V1_sens and the secondary side voltage sensor value V2_sens deviate from true values within the range of the maximum values ε1 and ε2 of the acquisition error, the initial duty ratio is always smaller than the theoretical duty ratio. It can be set to be larger or larger. Therefore, according to the power supply system S, the direction of the inrush current that can be generated when the voltage converter 3 is started can be limited to only one of the first battery 10 side and the second battery 20 side. It is sufficient to apply only one of them.

  (2) In the power supply system S, using the maximum value ε1 of the primary-side voltage acquisition error and the maximum value ε2 of the secondary-side voltage acquisition error, the initial duty of the lower arm 31 according to the above equation (3-1) The ratio γ1 is set. According to the power supply system S, by setting the initial duty ratio γ1 according to the above equation (3-1), the primary side voltage sensor value V1_sens and the secondary side voltage sensor value V2_sens have a maximum error ε1 with respect to the true value. , Ε 2, the initial duty ratio γ 1 can always be set smaller than the theoretical duty ratio, no matter how much the deviation is within the range of ε 2. For this reason, since the direction of the inrush current generated when starting up the voltage converter 3 can always be limited from the second battery 20 side to the first battery 10 side, measures against the inrush current can be applied only to the first battery 10 side. It is enough.

  (3) According to the power supply system S, by setting the initial duty ratio γ2 in accordance with the above equation (3-2), the voltage converter is driven while the lower arm 31 and the upper arm 32 are complementarily turned on / off. 3 is always limited from the second battery 20 side to the first battery 10 side.

  (4) According to the power supply system S, the larger one of the first battery 10 and the second battery 20 can be charged by the external charger C until it is fully charged. Therefore, according to the vehicle V equipped with the power supply system S, the travel distance can be increased. In the power supply system S, as described above, the direction of the inrush current that can be generated when the voltage converter 3 is started can be limited to only one of the first battery 10 side and the second battery 20 side. Therefore, in the power supply system S, by preventing the inrush current generated when the voltage converter 3 is started from flowing to the first battery 10 and the second battery 20 that can be fully charged by the external charger C, Deterioration of the batteries 10 and 20 can be suppressed while extending the travel distance of the vehicle V.

  (5) As described above, according to the power supply system S, the direction of the inrush current generated when the voltage converter 3 is started can always be limited from the second battery 20 side to the first battery 10 side. Further, in the power supply system S, the capacity of the second battery 20 is made larger than that of the first battery 10, and the second circuit 2 provided with the second battery 20 is provided with an external battery for fully charging the second battery 20. An external positive terminal 23 and an external negative terminal 24 to which the charger C is connected are provided. Thus, after the external battery charger C is connected to both terminals 23 and 24 and the second battery 20 is fully charged, when the power supply system S is started, the battery 2 enters the fully charged second battery 20. Since current can be prevented from flowing, deterioration of the second battery 20 can be suppressed while the second battery 20 is fully charged.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this. Within the scope of the gist of the present invention, the detailed configuration may be changed as appropriate.

  For example, in the above embodiment, the second battery 20 is a high-capacity type having an energy weight density superior to that of the first battery 10, and the first battery 10 has a high output weight density superior to that of the second battery 20. Although the case where it was set as the type | mold was demonstrated, this invention is not restricted to this. The first battery 10 may be a high capacity type and the second battery 20 may be a high output type.

  Moreover, although the said embodiment demonstrated the case where the one voltage converter 3 was provided between the 1st battery 10 and the 2nd battery 20, this invention is not restricted to this. Two voltage converters may be provided between the two batteries. In this case, one of the two voltage converters performs direct connection control in which both the upper arm and the lower arm are turned on, and the other is started under the initial duty ratios γ1 and γ2 according to the procedure described with reference to FIG. You may make it do.

  Moreover, although the said embodiment demonstrated the case where the 1st battery 10 which is a secondary battery and the 2nd battery 20 which is a secondary battery were used as a battery | storage device mounted in the power supply system S, this invention corresponds to this. Not exclusively. For example, a capacitor that can be discharged and charged may be used instead of the first battery 10. Similarly, the second battery 20 may be a capacitor that can be discharged and charged.

V ... Vehicle C ... External charger S ... Power supply system 1 ... First circuit 10 ... First battery (first capacitor)
15 ... Primary voltage sensor (first voltage acquisition means)
2 ... 2nd circuit 20 ... 2nd battery (2nd electrical storage device)
23 ... External positive terminal (connection part)
24 ... External negative terminal (connection part)
25 ... Secondary voltage sensor (second voltage acquisition means)
DESCRIPTION OF SYMBOLS 3 ... Voltage converter 31 ... Lower arm 32 ... Upper arm L ... Reactor 5 ... ECU (control apparatus)

Claims (5)

A first circuit having a first capacitor;
A second circuit having a second capacitor;
A voltage converter having an upper arm, a lower arm, and a reactor, for converting a voltage between the first circuit and the second circuit;
First voltage acquisition means for acquiring a value of a first voltage that is a voltage of the first circuit;
Second voltage acquisition means for acquiring a value of a second voltage that is a voltage of the second circuit;
A power supply system comprising a control device for controlling the voltage converter,
The second circuit is connected to both ends of a series connection body of the upper arm and the lower arm,
The first circuit is connected to the lower arm via the reactor,
The control device is configured to acquire a first voltage acquisition value by the first voltage acquisition unit, a second voltage acquisition value by the second voltage acquisition unit, and acquisition of the first voltage by the predetermined first voltage acquisition unit. Based on the error value and the predetermined error value of the second voltage acquired by the second voltage acquisition means, the duty ratios of the upper arm and the lower arm when the voltage converter is activated are set. A power supply system characterized by that. The first voltage acquisition value is V1_sens, the maximum value of the first voltage acquisition error by the predetermined first voltage acquisition means is ε1, the second voltage acquisition value is V2_sens, The maximum value of the second voltage acquisition error by the second voltage acquisition means is ε2, and the control device sets the duty ratio γ1 of the lower arm when the voltage converter is activated based on the following equation (1). The power supply system according to claim 1, wherein:

3. The power supply system according to claim 2, wherein the control device sets a duty ratio γ <b> 2 of the upper arm when the voltage converter is activated based on the following formula (2).

  2. The power supply system according to claim 1, wherein the larger one of the first capacitor and the second capacitor can be charged by an external charger until it is fully charged. The second battery has a larger capacity than the first battery,
The power supply system according to claim 2 or 3, wherein the second circuit is provided with a connection portion to which an external charger for fully charging the second capacitor is connected.

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