JP6094493B2 - Storage battery temperature riser - Google Patents

Description

  The present invention relates to a temperature increasing device for a storage battery.

  Conventionally, as can be seen in Patent Document 1 below, an in-vehicle power supply system that includes first and second storage batteries and first and second converters that boost output voltages of the first and second storage batteries is known. ing. Specifically, in this power supply system, the output voltage of each converter is applied to a three-phase inverter for driving the motor via a common power line. According to this power supply system, the capacity of the in-vehicle storage battery can be increased, and the cruising distance of the vehicle can be increased.

  Here, as the storage battery, a storage battery (for example, a lithium ion storage battery) having an input / output characteristic whose allowable upper limit value of input / output power when the temperature is low is lower than the allowable upper limit value of input / output power when the temperature is high ) Is used. For this reason, when the temperature of a storage battery is low, it is requested | required to raise the temperature rapidly.

  Therefore, in the technique described in Patent Document 1 below, the output voltage from the storage battery corresponding to the converter with the higher output voltage is made lower by changing the target values of the output voltages of the first and second converters. Current is sent to the storage battery corresponding to the converter. Thereby, the temperature of the storage battery is raised by heat generated in the internal resistance of the storage battery.

Japanese Patent Laid-Open No. 2008-60047

  Incidentally, a storage battery such as a lithium ion storage battery has a characteristic that impedance is large in a region where a fluctuation frequency of a current flowing through the storage battery is low in a low temperature state. Here, the current flowing between the storage batteries by the above-described temperature raising method that makes the target value of the output voltage different becomes quasi-stationary, and therefore the fluctuation frequency thereof becomes low. That is, the fluctuation frequency of the current flowing through the storage battery is included in the frequency region where the impedance is large. Therefore, in the above temperature raising method, a sufficient current for heat generation cannot be supplied to the storage battery, and there is a concern that the temperature increase rate of the storage battery is insufficient. In addition, when the temperature of the storage battery is low, if the current is made to flow between the storage batteries with the target value being different, there is a concern that the deterioration of the storage battery may progress.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to allow an upper limit of input / output power when its own temperature is low and an upper limit of input / output power when its own temperature is high. An object of the present invention is to provide a temperature increasing device for a storage battery that can be applied to a storage battery having characteristics lower than the value and that can suitably increase the temperature of the storage battery when the temperature of the storage battery is low.

  In order to solve the above problems, the present invention provides a plurality of storage batteries having a characteristic that an allowable upper limit value of input / output power when its own temperature is low is lower than an allowable upper limit value of input / output power when its own temperature is high (10, 20), one of the plurality of storage batteries divided into two is a first storage battery (10), the other is a second storage battery (20), a first reactor (12a), and an on operation Using the first storage battery as a power supply source, energy is stored in the first reactor, and the energy stored in the first reactor is released by an off operation to increase the output voltage of the first storage battery to thereby increase the first power line. (L1) and a first boost switching element (S1n) capable of outputting between the second power line (L2) and the first power line and the second power line by an ON operation. A first receiving switching element (S1p; S1a) for connecting a storage battery, a first booster (12) provided corresponding to the first storage battery, a second reactor (22a), and an ON operation The second storage battery is used as a power supply source to store energy in the second reactor, and the energy stored in the second reactor is released by an off operation to increase the output voltage of the second storage battery, thereby A second boosting switching element (S2n) capable of outputting between one power line and the second power line, and a second receiving switching for connecting the second storage battery between the first power line and the second power line by an ON operation. Element (S2p; S2a), the second booster (22) provided corresponding to the second storage battery, and the operation of the first booster switching element. In order to alternately perform the boosting operation of the output voltage of the first storage battery and the boosting operation of the output voltage of the second storage battery by operating the second boosting switching element, the first boosting switching element and the The voltage between the first power line and the second power line is higher than the output voltage of the second storage battery due to the boosting operation means for operating the second boosting switching element and the boosting operation by the operation of the first boosting switching element. During the period of high voltage, the voltage between the first power line and the second power line is changed to the first storage battery in accordance with the turning-on operation of the second receiving switching element and the boosting operation by the operation of the second boosting switching element. Alternately turning on the first receiving switching element during a period higher than the output voltage of the first storage And a temperature raising means for raising the temperature of the battery and the second storage battery.

  The voltage between the first and second power lines varies due to the boosting operation by operating the first and second boosting switching elements. For this reason, by causing the boosting operation means to alternately perform each boosting operation by operating each boosting switching element, voltage fluctuations caused by each boosting operation are alternately generated between the first and second power lines. .

  Assuming such a configuration, in the above invention, the voltage between the first and second power lines rises by the boosting operation by the operation of the first boosting switching element, and the voltage is higher than the output voltage of the second storage battery. The second receiving switching element is turned on during a period when the second receiving switching element becomes higher. Thereby, a current flows from the first storage battery to the second storage battery via the first booster and each power line. On the other hand, in the period in which the voltage between the first and second power lines rises due to the boosting operation by operating the second boosting switching element and the voltage is higher than the output voltage of the first storage battery, the first receiving switching element is Turn on. Thereby, a current flows from the second storage battery to the first storage battery via the second booster and each power line.

  Thus, in the situation where each boosting operation by the operation of each boosting switching element is performed alternately, the current flow direction between the first and second storage batteries is alternately repeated by turning on each switching element for receiving. It is possible to pass a current between the storage batteries while alternately switching between. That is, an alternating current can be passed between each storage battery. Thereby, the temperature of the first and second storage batteries can be suitably raised. Moreover, according to the said invention, unlike the temperature rising method described in the said patent document 1, progress of deterioration of a storage battery can also be suppressed.

1 is an overall configuration diagram of a power supply system according to a first embodiment. The figure which shows the allowable upper limit of the input / output power of a battery. The figure which shows the setting method of the switching frequency concerning 1st Embodiment. The figure which shows the equivalent circuit of the internal structure of a battery. The flowchart which shows the procedure of the battery temperature rising process concerning 1st Embodiment. The figure which shows the operation | movement aspect of each converter concerning the embodiment. The figure which shows the operation | movement aspect of each converter concerning the embodiment. The time chart which shows an example of the battery temperature rising process concerning the embodiment. The whole block diagram of the power supply system concerning 2nd Embodiment. The whole block diagram of the power supply system concerning 3rd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a storage battery temperature increasing device according to the present invention is applied to an in-vehicle power supply system will be described with reference to the drawings.

  As shown in FIG. 1, the power supply system includes first and second batteries 10 and 20, first and second converters 12 and 22, and a control device 30. In the present embodiment, lithium ion storage batteries are used as the batteries 10 and 20. In the present embodiment, the batteries 10 and 20 have the same configuration. Specifically, the batteries 10 and 20 have the same relationship between the open-circuit voltage with respect to the charging rate (SOC: ratio of the actual charge amount to the full charge amount), the full charge amount, the internal resistance value, and the like. Is used.

  The first converter 12 (corresponding to the “first boosting unit”) is a chopper type buck-boost converter, and includes a first reactor 12a, a first smoothing capacitor 12b, first upper and lower arm switching elements S1p, S1n, and 1 includes upper and lower arm diodes D1p and D1n. In this embodiment, IGBT is used as each switching element S1p and S1n.

  The first upper and lower arm switching elements S1p and S1n are connected in series with each other. Specifically, the collector of the first lower arm switching element S1n is connected to the emitter of the first upper arm switching element S1p. A first smoothing capacitor 12b is connected in parallel to the series connection body of the switching elements S1p and S1n.

  A series connection body of the first reactor 12a and the first battery 10 is connected in parallel to the first lower arm switching element S1n. Specifically, the positive terminal of the first battery 10 is connected to the opposite side of the both ends of the first reactor 12a from the connection point of the first upper and lower arm switching elements S1p, S1n. First upper and lower arm diodes D1p and D1n are connected in reverse parallel to the first upper and lower arm switching elements S1p and S1n.

  The second converter 22 (corresponding to the “second booster”) is a chopper-type step-up / down converter similar to the first converter. The second converter 22 includes a second reactor 22a, a second smoothing capacitor 22b, second upper and lower arm switching elements S2p and S2n, and second upper and lower arm diodes D2p and D2n. Here, in the present embodiment, the internal configuration of the second converter 22 is the same as the internal configuration of the first converter 12. For this reason, in this embodiment, detailed description of the internal configuration of the second converter 22 is omitted.

  Incidentally, in the present embodiment, the first lower arm switching element S1n corresponds to a “first boosting switching element”, and the first upper arm switching element S1p corresponds to a “first receiving switching element”. The second lower arm switching element S2n corresponds to a “second boosting switching element”, and the second upper arm switching element S2p corresponds to a “second receiving switching element”.

  A common first power line L1 is connected to the collectors of the first and second upper arm switching elements S1p and S2p. A common second power line L2 is connected to the emitters of the first and second lower arm switching elements S1n and S2n. These power lines L1 and L2 are connected to the input side of a multiphase inverter (three-phase inverter 40). A motor generator 42 is connected to the output side of the three-phase inverter 40. The motor generator 42 is a multi-phase rotating machine (three-phase rotating machine) as an in-vehicle main machine, and is connected to driving wheels 44 of the vehicle. As the motor generator 42, for example, a synchronous machine (permanent magnet synchronous machine) or an induction machine can be used. In the present embodiment, the motor generator 42 corresponds to “a predetermined power supply target”.

  The control device 30 generates operation signals g1p, g1n, g2p, and g2n for turning on / off the switching elements S1n, S2p, and S2n, and outputs the operation signals to the switching elements S1p, S1n, S2p, and S2n. Specifically, the control device 30 detects the potential difference between the first and second temperature sensors 50 and 52 that detect the temperatures of the first and second batteries 10 and 20 and the first and second power lines L1 and L2. The detection value of the sensor 54 is captured. The control device 30 generates the operation signals g1p, g1n, g2p, g2n based on these detected values.

  In particular, the control device 30 turns on and off the first and second lower arm switching elements S1n and S2n so as to boost the output voltage of the first and second batteries 10 and 20 and apply it to the input side of the three-phase inverter 40. To do. Specifically, the voltage detected by the voltage sensor 54 (hereinafter referred to as the actual output voltage Vh) is set to the target value of the output voltage of the first and second batteries 10 and 20 (hereinafter referred to as the first and second target voltages V1tgt and V2tgt). In order to control, the first and second lower arm switching elements S1n and S2n are turned on and off. Here, in the present embodiment, the first target voltage V1tgt and the second target voltage V2tgt are set to the same value.

  The step-up operation of each converter 12, 22 will be described using the first converter 12 as an example. Specifically, the first lower arm switching element S1n is turned on while the first upper arm switching element S1p is turned off. Thereby, magnetic energy is accumulated in the first reactor 12a. Thereafter, by switching the first lower arm switching element S1n to the off operation, the magnetic energy accumulated in the first reactor 12a is released, the output voltage of the first battery 10 is increased, and the first and second power lines L1, L2 are increased. It is output during L2.

  Note that the control device 30 also performs a process of operating the three-phase inverter 40 to perform power running control using the motor generator 42 as an electric motor and regenerative control using the motor generator 42 as a generator during deceleration of the vehicle. This process is a process of operating the three-phase inverter 40 by well-known vector control or the like to control the torque of the motor generator 42 to the command torque.

  Then, the temperature rising process of the 1st, 2nd batteries 10 and 20 which is the characteristic structure concerning this embodiment is demonstrated.

  This process is executed by the control device 30, and by passing an alternating current between the batteries 10 and 20 while alternately switching the battery as the power supply source and the battery as the power supply destination between the batteries 10 and 20. In this process, each battery 10 and 20 is heated.

  That is, as shown in FIG. 2, the lithium ion storage battery has an allowable upper limit value of output power (allowable upper limit value of power that can be discharged per unit time, hereinafter, maximum output power Poutmax) when its own temperature is low. It has characteristics that are lower than the maximum output power Poutmax when its own temperature is high. In addition, the lithium ion storage battery has an allowable upper limit value of input power when its own temperature is low (allowable upper limit value of power that can be accepted per unit time, hereinafter, maximum input power Pinmax) when its own temperature is high. It has a characteristic lower than the maximum input power Pinmax. In FIG. 2, a temperature region where the temperature of each of the batteries 10 and 20 is lower than the first specified temperature Tα is defined as a low temperature region, and a temperature region equal to or higher than the first specified temperature Tα and lower than the second specified temperature Tβ is defined as a normal temperature region. Yes.

  When the temperatures of the batteries 10 and 20 are in the low temperature region, the input / output characteristics of the power of the batteries 10 and 20 are deteriorated. In particular, in the in-vehicle power supply system, there is a problem of a decrease in the maximum output power Poutmax when the temperatures of the batteries 10 and 20 are in a low temperature region. For this reason, when the temperature of each battery 10 and 20 exists in a low temperature area | region, it is requested | required to heat up each battery 10 and 20 rapidly. Therefore, a temperature raising process for flowing an alternating current between the batteries 10 and 20 is performed.

  Here, in the present embodiment, as shown in FIG. 3, the frequency of the alternating current that flows between the batteries 10 and 20 is set in the high admittance region. The high admittance region is determined by commonly known battery characteristics, ie, resistance due to chemical reaction at the electrode interface, resistance due to ion diffusion in the electrolyte, and the synthesis circuit of the electrical circuit connected to the battery. . FIG. 4 is an equivalent circuit diagram in which the batteries 10 and 20 are modeled from these characteristics.

  In the illustrated example, each of the batteries 10 and 20 is modeled mainly from a negative electrode reaction resistance Rn, a negative electrode electric double layer capacity Cn, a positive electrode reaction resistance Rp, a positive electrode electric double layer capacity Cp, and an electrolyte resistance Rsol. It was supposed to be. Here, the negative electrode reaction resistance Rn is a charge transfer resistance on the negative electrode terminal An side, and the negative electrode electric double layer capacitance Cn is a capacitance of an electric double layer formed at the interface between the negative electrode terminal An and the electrolytic solution. Further, the positive electrode reaction resistance Rp is a charge transfer resistance on the positive electrode terminal Ap side, and the positive electrode electric double layer capacitance Cp is a capacitance of an electric double layer formed at the interface between the positive electrode terminal Ap and the electrolytic solution. Further, the electrolyte resistance Rsol is a resistance including a resistance of the electrolyte and a metal resistance such as a current collector foil.

  Here, in a circuit including a series connection body of capacitor components Cp and Cn of the batteries 10 and 20 and inductors 60 (inductor components) connected to terminals of the batteries 10 and 20, the resonance frequency of the circuit, and The predetermined frequency range determined by the frequency characteristics of the battery impedance is the high admittance region. This region is a range defined by the target temperature rise performance of the battery. Examples of the target temperature increase performance include a temperature increase amount per unit time of the battery (hereinafter referred to as a temperature increase rate). Specifically, in order to increase the current temperature of the battery to a predetermined temperature (for example, a target temperature Ttgt described later) within the target time, the current temperature of the battery, the predetermined temperature, and the target time (for example, the current temperature from the predetermined temperature is changed). Based on the value obtained by dividing the subtracted value by the target time), the value of the current to be supplied to the battery required to realize the temperature increase rate is determined. Then, a high admittance region capable of realizing the determined current value is determined. In addition, as the inductor 60, for example, the wiring impedance in the electric path from the positive terminal of each battery 10 and 20 to the first power line L1 via each reactor 12a and 22a and each upper arm switching element S1p and S2p. Can be mentioned.

  The admittance characteristics are determined by the specifications of the converter (boost circuit) and the battery. The admittance characteristic is such that the admittance in the high admittance region is higher than the admittance in the frequency region adjacent to the low frequency side and the high frequency side of the high admittance region (see FIG. 3 above). For this reason, by setting the frequency of the alternating current flowing between the batteries 10 and 20 within the high admittance region, the power of the capacitor component of the batteries 10 and 20 can be exchanged between the batteries 10 and 20. it can. That is, a sufficient current for generating heat in the internal resistances of the batteries 10 and 20 can flow. Thereby, each battery 10 and 20 can be heated effectively, and each battery 10 and 20 can be heated up effectively.

  FIG. 5 shows the procedure of the temperature increasing process for each of the batteries 10 and 20. This process is repeatedly executed by the control device 30 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, the temperature of the first battery 10 detected by the first temperature sensor 50 (hereinafter referred to as the first temperature Tbt1) and the second battery 20 detected by the second temperature sensor 52 are detected. It is determined whether at least one of the temperatures (hereinafter referred to as the second temperature Tbt2) is lower than the target temperature Ttgt. This process is a process for determining whether or not an execution condition for the temperature raising process is satisfied. The target temperature Ttgt is a temperature set to an arbitrary temperature within the normal temperature range shown in FIG. 2, and is set to the first specified temperature Tα, for example.

  If an affirmative determination is made in step S10, the process proceeds to step S12 to set the target voltages V1tgt and V2tgt. In the present embodiment, since the target voltages V1tgt and V2tgt are set to the same value, the target voltages V1tgt and V2tgt are hereinafter simply referred to as the target voltage Vtgt. In the present embodiment, the target voltage Vtgt is set higher as the required input voltage of the three-phase inverter 40 (command power of the motor generator 42) is larger.

  In the following step S14, the switching frequency fsw of each switching element S1p, S1n, S2p, S2n is calculated. In the present embodiment, the switching frequency fsw is set in the high admittance region shown in FIG. More specifically, the switching frequency fsw is set to a frequency having the highest admittance in the high admittance region. The reciprocal of the switching frequency fsw is one cycle Tsw of on / off operation of each switching element.

  In subsequent steps S16 to S22, the command value (first and second lower arm command values R1nc, R2nc) of the ratio of the on operation time (Duty ratio) to one cycle of the on / off operation of the first and second lower arm switching elements S1n, S2n. And the duty ratio command values (first and second upper arm command values R1pc and R2pc) of the first and second upper arm switching elements S1p and S2p.

  Specifically, in step S16, based on the target voltage Vtgt, the duty ratio reference values (first and second reference values R1f, R2f) for the first and second lower arm switching elements S1n, S2n are calculated. Each of the reference values R1f and R2f is a feedforward operation amount required to set the actual output voltage Vh to the target voltage Vtgt. In the present embodiment, the first and second reference values R1f and R2f are set larger as the target voltage Vtgt is higher. In the present embodiment, the actual output voltage Vh when the potential of the first power line L1 is higher than the potential of the second power line L2 is defined as positive.

  In subsequent step S18, the first and second correction values R1b and R2b are calculated based on the deviation ΔV between the target voltage Vtgt and the actual output voltage Vh. Each of the correction values R1b and R2b is a feedback operation amount required for feedback control of the actual output voltage Vh to the target voltage Vtgt. In this embodiment, the deviation ΔV is calculated as a value obtained by subtracting the actual output voltage Vh from the target voltage Vtgt, and the correction values R1b and R2b are calculated by proportional-integral control based on the calculated deviation ΔV.

  In the following step S20, first and second lower arm command values R1nc and R2nc are calculated as an addition value of the first and second reference values R1f and R2f and the first and second correction values R1b and R2b.

  In subsequent step S22, first and second upper arm command values R1pc and R2pc are calculated based on the first and second lower arm command values R1nc and R2nc. In the present embodiment, the upper arm command values R1pc and R2pc are set larger as the lower arm command values R1nc and R2nc are larger. In view of the fact that as each lower arm command value R1nc, R2nc increases, the period during which the actual output voltage Vh is higher than the average value of one cycle of the actual output voltage Vh becomes longer, the power from the battery serving as the power supply source This is a setting for securing time for flowing current to the battery as the supply destination.

  In subsequent steps S24 to S38, the second upper arm switching element S2p is turned on in a period in which the actual output voltage Vh is higher than the output voltage of the second battery 20, and the actual output voltage Vh is output from the first battery 10. The first upper arm switching element S1p is turned on alternately in a period higher than the voltage.

  Specifically, in step S24, the first lower arm switching element S1n is turned on for the on-operation time indicated by the first lower arm command value R1nc, and in step S26, the off indicated by the first lower arm command value R1nc. The first lower arm switching element S1n is turned off for the operation time. In the subsequent step S28, the second upper arm switching element S2p is turned on for the on operation time indicated by the second upper arm command value R2pc. In step S30, the off operation time indicated by the second upper arm command value R2pc. Only the second upper arm switching element S2p is turned off. Here, each ON operation time becomes longer as each command value becomes larger, and each OFF operation time becomes shorter as each command value becomes larger.

  FIG. 6 shows that the second upper arm switching element S2p is turned on in a situation where the actual output voltage Vh becomes higher than the output voltage V2 of the second battery 20 with the step-up operation by turning on and off the first lower arm switching element S1n. Showed how it was done. Thus, the first battery 10 is used as a power supply source, and the second battery 20 is passed through the first reactor 12a, the first upper arm diode D1p, the first power line L1, the second upper arm switching element S2p, and the second reactor 22a. Current will flow into the. In the present embodiment, the output voltage V2 of the second battery 20 is detected by second voltage detection means (voltage sensor) (not shown) that detects the output voltage of the second battery 20.

  Returning to the description of FIG. 5 above, in step S32, the second lower arm switching element S2n is turned on for the on operation time indicated by the second lower arm command value R2nc. In step S34, the second lower arm command value is turned on. The second lower arm switching element S2n is turned off for the off operation time indicated by R2nc. In the following step S36, the first upper arm switching element S1p is turned on for the on operation time indicated by the first upper arm command value R1pc, and in step S38, the off operation time indicated by the first upper arm command value R1pc. Only the first upper arm switching element S1p is turned off. Here, each ON operation time becomes longer as each command value becomes larger, and each OFF operation time becomes shorter as each command value becomes larger.

  FIG. 7 shows that the first upper arm switching element S1p is turned on in a situation where the actual output voltage Vh becomes higher than the output voltage V1 of the first battery 10 with the step-up operation by turning on and off the second lower arm switching element S2n. Showed how it was done. Thereby, the second battery 20 is used as a power supply source, and the first battery 10 is passed through the second reactor 22a, the second upper arm diode D2p, the first power line L1, the first upper arm switching element S1p, and the first reactor 12a. Current will flow into the. In the present embodiment, the output voltage V1 of the first battery 10 is detected by first voltage detection means (voltage sensor) (not shown) that detects the output voltage of the first battery 10.

  Returning to the description of FIG. 5, the process returns to step S10 after the process of step S38 is completed. If a negative determination is made in step S10, this series of processes is temporarily terminated. In the present embodiment, the switching frequency fsw is changed during the temperature raising process so that the switching frequency fsw of each of the switching elements S1p, S1n, S2p, S2n is in the high admittance region. For this reason, when the temperature raising process is completed, the change of the switching frequency fsw is cancelled. That is, the switching frequency fsw when the temperature raising process is performed may be different from the switching frequency fsw when the temperature raising process is not performed.

  Incidentally, in the present embodiment, the processes in steps S24, S26, S32, and S34 correspond to the “boosting operation means”. In addition, the processes in steps S28, S30, S36, and S38 correspond to “temperature raising means”.

  FIG. 8 shows an example of the temperature raising process according to the present embodiment. Specifically, FIGS. 8A to 8D show the transition of the operation state of each switching element S1p, S1n, S2p, S2n, and FIG. 8E shows the transition of the actual output voltage Vh. FIG. 8F shows the transition of the current Ibt1 flowing through the first battery 10, and FIG. 8G shows the transition of the current Ibt2 flowing through the second battery 20. 8 (f) and 8 (g), the direction in which current is output from each of the batteries 10 and 20 is positive (refer to FIGS. 6 and 7).

  In the illustrated example, the first and second lower arm command values R1nc and R2nc are set to the same value, and the first and second upper arm command values R1pc and R2pc are set to the same value. For this reason, the ON operation time Tnon in the ON / OFF operation 1 cycle Tsw of the lower arm switching elements S1n, S2n is set to the same time, and the ON operation time Tpon in the ON / OFF operation 1 cycle Tsw of the upper arm switching elements S1p, S2p. Are set at the same time.

  Further, in FIG. 8, the temperature raising process in a state where the motor generator 42 is in a stopped state (stopped state) and the average value of one cycle of the currents Ibt1 and Ibt2 flowing in the first and second batteries 10 and 20 is substantially zero. Is shown.

  As shown in the drawing, the state 1 and the state 2 are alternately repeated by the temperature raising process. Specifically, in state 1 shown at times t1 to t3, in the period in which the actual output voltage Vh is higher than the output voltage V2 of the second battery 20 due to the step-up operation by the on / off operation of the first lower arm switching element S1n, This is a state where the upper arm switching element S2p is turned on. Specifically, after the first lower arm switching element S1n is turned on for the on operation time Tnon from time t1, the second upper arm switching element S2p is turned on for the on operation time Tpon from time t2. In particular, in the present embodiment, the ON operation start timing (time t2) of the second upper arm switching element S2p is set to a timing at which the actual output voltage Vh reaches its peak value.

  In the subsequent state 2 from time t3 to t5, the first upper arm is in a period in which the actual output voltage Vh is higher than the output voltage V1 of the first battery 10 due to the step-up operation by turning on and off the second lower arm switching element S2n. In this state, the switching element S1p is turned on. Specifically, after the second lower arm switching element S2n is turned on for the on operation time Tnon from time t3, the first upper arm switching element S1p is turned on for the on operation time Tpon from time t4. In particular, in the present embodiment, the ON operation start timing (time t4) of the first upper arm switching element S1p is set to a timing at which the actual output voltage Vh reaches its peak value.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) In a situation where the step-up operation by the on / off operation of the lower arm switching elements S1n and S2n is alternately performed, the temperature raising process for alternately repeating the on operation of the upper arm switching elements S1p and S2p was performed. Thereby, each battery 10 and 20 can be heated effectively. Moreover, according to such a temperature raising process, the progress of the deterioration of the batteries 10 and 20 can be suppressed.

  Further, according to the temperature raising process, for example, since the average value of one cycle of the actual output voltage Vh becomes substantially the target voltage Vtgt, each converter 12 in the period when the actual output voltage Vh is higher than the average value. The output power of 22 can be used for increasing the temperature of the batteries 10 and 20. Here, it is considered that the fluctuation of the actual output voltage Vh (deviation from the above average value) does not greatly affect the torque of the motor generator 42. For this reason, according to the present embodiment, it is possible to raise the temperature of each of the batteries 10 and 20 while suppressing a decrease in torque of the motor generator 42.

  (2) From the timing at which the actual output voltage Vh reaches its peak value due to the step-up operation by the on / off operation of the first lower arm switching element S1n, to the timing before the on operation start timing of the second lower arm switching element S2n immediately after this timing The period was set as the ON operation period of 2nd upper arm switching element S2p. Also, the period from the timing when the actual output voltage Vh reaches its peak value due to the step-up operation by the ON / OFF operation of the second lower arm switching element S2n to the timing before the ON operation start timing of the first lower arm switching element S1n immediately after this timing Is the ON operation period of the first upper arm switching element S1p. Thus, by turning on the upper arm switching elements S1p and S2p during a part of the period in which the actual output voltage Vh is higher than the output voltage of the batteries 10 and 20, the temperature of the batteries 10 and 20 is increased. Therefore, it is possible to suppress a decrease in power supplied from each converter 12 and 22 to motor generator 42. Thereby, the torque fall of motor generator 42 can be controlled suitably.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, the configuration of each converter 12, 22 is changed.

  FIG. 9 shows the overall configuration of the power supply system according to the present embodiment. In FIG. 9, the same members as those shown in FIG. 1 are given the same reference numerals for the sake of convenience.

  As illustrated, the first and second converters 12 and 22 further include first and second bypass switching elements S1a and S2a, and first and second bypass diodes D1a and D2a. In the present embodiment, IGBTs are used as the detour switching elements S1a and S2a.

  The first bypass switching element S <b> 1 a connects the first power line L <b> 1 and the positive terminal of the first battery 10. Specifically, the first power line L1 is connected to the collector of the first bypass switching element S1a, and the positive terminal of the first battery 10 is connected to the emitter. On the other hand, the second bypass switching element S <b> 2 a connects between the first power line L <b> 1 and the positive terminal of the second battery 20. Specifically, the first power line L1 is connected to the collector of the second bypass switching element S2a, and the positive terminal of the second battery 20 is connected to the emitter. The first and second bypass switching elements S1a and S2a are connected in reverse parallel to the first and second bypass diodes D1a and D2a. The first and second bypass switching elements S1a and S2a are turned on and off by operation signals g1a and g2a output from the control device 30.

  Incidentally, in the present embodiment, the first bypass switching element S1a corresponds to a “first receiving switching element”, and the second bypass switching element S2a corresponds to a “second receiving switching element”. The first upper arm diode D1p corresponds to a “first rectifier element”, and the second upper arm diode D2p corresponds to a “second rectifier element”.

  Then, the temperature rising process concerning this embodiment is demonstrated.

  In the present embodiment, in the temperature raising process, the first and second bypass switching elements S1a and S2a are turned on instead of turning on the first and second upper arm switching elements S1p and S2p. This is a configuration for reducing the impedance of the flow path of the current flowing between the batteries 10 and 20. That is, each of the reactors 12a and 22a may function as a choke coil that prevents current flow depending on the frequency of the alternating current flowing between the batteries 10 and 20. In this case, there is a concern that the alternating current flowing through each of the batteries 10 and 20 decreases, and the temperature of each of the batteries 10 and 20 cannot be effectively increased.

  In order to solve such a problem, the first and second bypass switching elements S1a and S2a are provided. Specifically, the second bypass switching element S2a is turned on during a period in which the actual output voltage Vh is higher than the output voltage of the second battery 20 in accordance with the step-up operation by turning on / off the first lower arm switching element S1n. Thereby, as shown with the broken line in a figure, an electric current flows into the 2nd battery 20 by the path | route which avoids the 2nd reactor 22a from the 1st battery 10. FIG. On the other hand, the first bypass switching element S1a is turned on during a period in which the actual output voltage Vh is higher than the output voltage of the first battery 10 due to the step-up operation by turning on and off the second lower arm switching element S1n. As a result, as indicated by the alternate long and short dash line in the figure, current flows from the second battery 20 to the first battery 10 through a path that avoids the first reactor 12a.

  Thus, in the present embodiment, an alternating current is passed between the batteries 10 and 20 through a low impedance path. According to such a configuration, it is possible to improve the degree of freedom of setting the switching frequency fsw, such as avoiding the setting of the switching frequency fsw that avoids the frequency at which the flow of alternating current is hindered by the reactors 12a and 22a.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  In the present embodiment, the configuration of each converter 12, 22 is changed.

  FIG. 10 shows the overall configuration of the power supply system according to the present embodiment. In FIG. 10, the same members as those shown in FIG. 9 are given the same reference numerals for the sake of convenience.

  As illustrated, in the present embodiment, the first and second upper arm switching elements S1p and S2p are removed. The first and second bypass diodes D1a and D2a are also removed. According to the present embodiment, the number of components of the power supply system can be reduced, and as a result, the cost of the power supply system can be reduced.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the first embodiment, the actual output voltage Vh is greater than the output voltage of the second battery 20 during the ON operation period of the second upper arm switching element S2p with the step-up operation by the ON / OFF operation of the first lower arm switching element S1n. However, it is not necessary to be a part of the higher period, but the whole period. The on-operation period of the first upper arm switching element S1p is also the entire period during which the actual output voltage Vh becomes higher than the output voltage of the first battery 10 due to the boosting operation by the on / off operation of the second lower arm switching element S2n. Also good.

  The temperature raising process shown in FIG. 8 of the first embodiment may be performed in a state where the motor generator 42 is driven (a state where the vehicle is traveling). In this case, the average value of one cycle of the currents Ibt1 and Ibt2 flowing through the first and second batteries 10 and 20 is a value larger than zero. Even under such circumstances, it is considered that an alternating current can flow between the batteries 10 and 20, and the temperature of the batteries 10 and 20 can be effectively increased.

  In each of the above embodiments, the power supply system includes two batteries and two converters corresponding to these batteries, but is not limited thereto. For example, a power supply system including three or more batteries and three or more converters corresponding to these batteries may be used. Specifically, in this power supply system, the opposite side of the both ends of the upper arm switching element constituting each converter to the side connected to the lower arm switching element is connected to the first power line L1. Moreover, the opposite side to the side connected with the upper arm switching element among the both ends of the lower arm switching element which comprises each converter is connected to the 2nd electric power line L2. In the case of adopting such a configuration, the number of batteries serving as power supply sources and the number of batteries serving as power supply destinations for the temperature rising process of each battery are not limited to one, and may be plural. . Specifically, for example, in the case of a power supply system including four batteries and four converters corresponding to these batteries, one of these batteries divided into two (two batteries) corresponds to the “first storage battery”, The other corresponds to the “second storage battery”. Then, the two converters corresponding to the first storage battery correspond to “first booster”, and the two converters corresponding to the second storage battery correspond to “second booster”.

  In the first embodiment, the first target voltage V1tgt and the second target voltage V2tgt are set to the same value. However, the present invention is not limited to this, and may be set to different values. Even in this case, the second upper arm switching element S2p is turned on or the actual output voltage Vh is reduced in all or part of the period in which the actual output voltage Vh is higher than the output voltage V2 of the second battery 20. The batteries 10 and 20 can be heated by turning on the first upper arm switching element S1p during all or part of the period higher than the output voltage V1 of the first battery 10.

  -The "storage battery" is not limited to the lithium ion storage battery. In short, if the storage battery has a characteristic that the allowable upper limit value of the input / output power when the own temperature is low is lower than the allowable upper limit value of the input / output power when the own temperature is high, the nickel hydride storage battery, etc. The storage battery may be used.

  10, 20 ... first and second batteries, 12, 22 ... first and second converters, L1, L2 ... first and second power lines.

Claims (4)

Applicable to a plurality of storage batteries (10, 20) having a characteristic that the allowable upper limit value of input / output power when its own temperature is low is lower than the allowable upper limit value of input / output power when its own temperature is high,
One of the plurality of storage batteries divided into two is a first storage battery (10), the other is a second storage battery (20),
The first reactor (12a) is turned on to store energy in the first reactor using the first storage battery as a power supply source, and is turned off to release the energy stored in the first reactor. A first step-up switching element (S1n) capable of increasing the output voltage of the storage battery and enabling output between the first power line (L1) and the second power line (L2); and the first power line and the second power line by an ON operation. A first receiving switching element (S1p; S1a) for connecting the first storage battery between the first booster (12) provided corresponding to the first storage battery;
Energy is stored in the second reactor by using the second reactor (22a) and the second storage battery as a power supply source by an ON operation, and the energy stored in the second reactor is released by an OFF operation. A second step-up switching element (S2n) capable of increasing the output voltage of the storage battery to enable output between the first power line and the second power line; and the second boosting switching element (S2n) between the first power line and the second power line by an ON operation. A second receiving switching element (S2p; S2a) for connecting two storage batteries, and a second booster (22) provided corresponding to the second storage battery;
In order to alternately perform the boost operation of the output voltage of the first storage battery by the operation of the first boost switching element and the boost operation of the output voltage of the second storage battery by the operation of the second boost switching element, Boosting operation means for operating the first boosting switching element and the second boosting switching element;
The second receiving switching element is turned on during a period in which the voltage between the first power line and the second power line is higher than the output voltage of the second storage battery in accordance with the boosting operation by the operation of the first boosting switching element. In the period when the voltage between the first power line and the second power line is higher than the output voltage of the first storage battery in accordance with the operation and the step-up operation by the operation of the second step-up switching element. A temperature raising means for raising the temperature of the first storage battery and the second storage battery by alternately turning on the switching element for switching,
A temperature increasing device for a storage battery, comprising: Each of the first booster and the second booster is configured to be able to supply power to a predetermined power supply target (42) via each power line,
The temperature raising means starts from the timing at which the voltage between the first power line and the second power line reaches its peak value in accordance with the step-up operation by operating the first step-up switching element. The period before the switching element on-operation start timing is set as the on-operation period of the second receiving switching element, and the boosting operation by the operation of the second boosting switching element is performed between the first power line and the second power line. The period from the timing when the voltage reaches its peak value to the timing before the ON operation start timing of the first boosting switching element immediately after this timing is defined as the ON operation period of the first receiving switching element. Item 2. A storage battery temperature increasing device according to Item 1. One end of the first reactor is connected to a positive terminal of the first storage battery, and the other end is connected to one end of the first boost switching element,
One end of the first receiving switching element (S1p) is connected to the side where the first reactor is connected among both ends of the first boosting switching element, and the side where the first reactor is connected On the opposite side, the negative electrode terminal of the first storage battery and the second power line are connected,
The first power line is connected to the opposite side of the first receiving switching element to the side where the first boost switching element is connected,
One end of the second reactor is connected to a positive terminal of the second storage battery, and the other end is connected to one end of the second boost switching element,
One end of the second receiving switching element (S2p) is connected to the side to which the second reactor is connected among both ends of the second boosting switching element, and the side to which the second reactor is connected On the opposite side, the negative electrode terminal of the second storage battery and the second power line are connected,
3. The first power line is connected to the opposite side of the second receiving switching element to the side where the second boost switching element is connected. Battery storage temperature riser. One end of the first reactor is connected to a positive terminal of the first storage battery, and the other end is connected to one end of the first boost switching element,
The negative terminal of the first storage battery and the second power line are connected to the opposite side of the first boost switching element to the side where the first reactor is connected,
The first booster has one end connected to an electrical path connecting the first reactor and the first booster switching element, the other end connected to the first power line, and the first reactor A first current flowing in a first direction from the electric path side connecting the first boosting switching element to the first power line side, and restricting a current flowing in a direction opposite to the first direction; 1 rectifier element (D1p) is further provided,
The first receiving switching element (S1a) has one end connected to the first power line and the other end connected to a positive terminal of the first storage battery.
One end of the second reactor is connected to a positive terminal of the second storage battery, and the other end is connected to one end of the second boost switching element,
A negative electrode terminal of the second storage battery and the second power line are connected to a side opposite to the side where the second reactor is connected among both ends of the second boost switching element,
The second boosting unit has one end connected to an electrical path connecting the second reactor and the second boosting switching element, the other end connected to the first power line, and the second reactor. A second current flowing in the second direction from the electrical path connecting the second boosting switching element to the first power line, and restricting a current flowing in a direction opposite to the second direction; Further comprising two rectifying elements (D2p),
The storage battery according to claim 1 or 2, wherein one end of the second receiving switching element (S2a) is connected to the first power line and the other end is connected to a positive terminal of the second storage battery. Temperature riser.

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