JP5151900B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter that converts a voltage applied to a primary coil of a transformer into a predetermined voltage via a secondary coil and outputs the result.

  As this type of power converter, for example, as can be seen in Patent Document 1 below, an apparatus that steps down the voltage of a high voltage battery and outputs it to a low voltage battery has been proposed. Here, the output voltage is controlled by controlling the ratio (time ratio) of the on time to one cycle of the on / off operation of the switching element provided on the primary side of the transformer included in the converter. As a result, a desired voltage can be applied to the low voltage battery regardless of fluctuations in the voltage of the high voltage battery.

In addition, as this kind of power converter device, there exists a thing described in the following patent document 2, for example.
Japanese Patent Laid-Open No. 2005-51994 JP 2005-295731 A

  However, in the converter described in Patent Document 1, when the switching element provided on the primary side is operated at the duty ratio D, the voltage applied between the input and output terminals is “ 1 / (1-D) "times. For this reason, depending on the value of the duty ratio D, the voltage applied to the switching element provided on the primary side becomes excessive, so that it is required to use a high withstand voltage element as the switching element.

  The present invention has been made to solve the above-described problems, and its purpose is to convert the voltage applied to the primary coil of the transformer into a predetermined value via the secondary coil and output it. Thus, an object of the present invention is to provide a power converter that can suitably suppress a required increase in breakdown voltage.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

According to the first aspect of the present invention, in the power converter that converts the voltage applied to the primary coil of the transformer into a predetermined value via the secondary coil and outputs the voltage, the power is generated in the secondary coil of the transformer 1. Voltage application means is provided to enable application of a voltage obtained by dividing the input voltage to the primary side coil in two ways in which the polarities of the voltages are opposite to each other. A plurality of primary side coils corresponding to the coils are provided , and the voltage application means sets the division number of the input voltage to 3 or more .

  In the above invention, since the voltage obtained by dividing the input voltage is applied to the primary coil by the voltage application means, the voltage application means converts the divided voltage into a predetermined value via the secondary coil. A voltage similar to that of the output power conversion circuit is applied. For this reason, it is possible to suitably suppress the required increase in breakdown voltage. In addition, since a plurality of primary coils corresponding to one secondary coil are provided, the amount of energy handled by each primary coil can be reduced.

Furthermore, in the said invention, the voltage applied to a voltage application means can be reduced suitably. In particular, it is easy to make the voltage applied to the voltage applying means smaller than the input voltage.

According to a second aspect of the invention of claim 1 Symbol placement, the voltage applying means is characterized by an even number of division number of the input voltage.

  In the above-mentioned invention, the utilization degree of a plurality of secondary side coils corresponding to one secondary side coil can be made mutually the same, performing appropriately the reset processing of the magnetic flux of the secondary side coil.

According to a third aspect of the present invention, in the first or second aspect of the present invention, in the voltage application cycle in which the divided voltages are applied instead of the primary coil, the divided voltages are The apparatus further comprises means for operating the voltage application means so that the application times are equal to each other.

  In the above invention, since the voltage application process by operating the voltage application means has symmetry, it is easy to make the divided voltage values equal to each other.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the transformer includes a pair of transformers in which primary coils are connected in series to each other. Means are provided for reversing the voltage polarities that allow current to flow between the secondary coils.

In the above invention, when the divided voltage is applied to the primary side coil in two ways such that the polarities of the voltages generated in the secondary side coil are opposite to each other, in which aspect the voltage is applied Accordingly, current can be passed through the secondary side coils that are different from each other. In addition, in the voltage application cycle, by setting “0 <application period of each divided voltage ≦ voltage application cycle / (number of divisions of input voltage)”, output is performed according to the application period of each divided voltage. The voltage can be controlled. For this reason, the invention specific matter according to claim 3 which is a condition for equalizing each divided voltage value and the condition for controlling the output voltage can be made independent of each other.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the voltage applying means includes a number of capacitors equal to the number of divisions of the input voltage, and both of the capacitors. A voltage between electrodes can be applied to the primary coil.

In the above invention, the input voltage can be suitably divided by the capacitor. In particular, when the above invention has the invention-specifying matters described in claim 3 , the partial pressure values can be made equal to each other.

A sixth aspect of the present invention is the invention according to any one of the first to fourth aspects, wherein the voltage applying means includes a number of capacitors that is one smaller than the number of divisions of the input voltage. And a voltage obtained by subtracting a sum of voltages between both electrodes of the capacitor from the input voltage, respectively, can be applied to the primary coil.

In the above invention, the input voltage can be suitably divided by the capacitor. In particular, when the above invention has the invention-specifying matters described in claim 3 , the partial pressure values can be made equal to each other.

The invention according to claim 7 is the invention according to any one of claims 1 to 4 , wherein the input voltage is a voltage at both ends of an assembled battery which is a series connection body of battery cells, and the voltage application means Is characterized in that the input voltage is divided by taking out an electrode voltage of an intermediate battery cell constituting the assembled battery.

  In the above invention, the input voltage can be suitably divided while suppressing or avoiding the addition of new hardware means.

The invention according to claim 8 is the invention according to any one of claims 1 to 7 , wherein the secondary coil of the transformer includes a pair of secondary coils, and the pair of secondary coils The rectifier is further provided with rectifying means for reversing the voltage polarities that allow current flow.

  In the above invention, when a voltage obtained by dividing the input voltage is applied to the primary coil in two ways in which the polarities of the voltages generated in the secondary coil are opposite to each other, Depending on whether it is applied, a current can be passed through different secondary coils.

The invention according to claim 9 is the invention according to any one of claims 1 to 8 , wherein the secondary side coil of the transformer includes a pair of secondary side coils, and the pair of secondary side coils The apparatus further comprises opening / closing means for opening / closing each of the pair of loop circuits including the respective circuits.

  In the above invention, by providing the opening / closing means, the divided voltage of the input voltage is applied to the primary side coil by each of two modes in which the polarities of the voltages generated in the secondary side coil are opposite to each other. At this time, the current flowing through the secondary coil can be rectified.

The invention of claim 10, wherein, in the invention according to any one of claim 1 to 9 voltage the output is characterized by lower than the input voltage.

  In the above-described invention, since the power conversion device steps down and outputs the input voltage, there is little demerit due to a decrease in the output voltage caused by dividing and using the input voltage.

The invention according to an eleventh aspect is the invention according to any one of the first to tenth aspects, wherein the voltage generated in the secondary coil of the transformer is alternated in two ways in which the polarities are opposite to each other. And a means for operating the voltage applying means to apply a voltage obtained by dividing the input voltage to the primary coil of the transformer.

  In the above invention, the voltage obtained by dividing the input voltage is alternately applied to the primary coil of the transformer in two ways such that the polarities of the voltages generated in the secondary coil of the transformer are opposite to each other. Whenever the divided voltage is applied twice, the magnetic flux of the secondary coil can be suitably reset.

The invention described in claim 12 is the invention described in claim 9 , wherein the output voltage is lower than the input voltage, and both the pair of loop circuits are operated by operating the opening / closing means. The input voltage is obtained by periodically repeating a process for making a closed loop, a process for making one of the pair of loop circuits a closed loop, a process for making both of them closed loop, and a process for making the other of the loop circuits closed loop. Further, it is further characterized by further comprising a boost control means for performing a process of boosting and outputting the output side voltage.

  When the power conversion device is intended for use as a step-down converter as in the above invention, it is difficult to supply power from the low voltage side (original output side) to the high voltage side (original input side). In this regard, in the above-described invention, when both the pair of loop circuits are closed-looped, energy is stored in the secondary coil, whereby the low-voltage side voltage can be boosted and output to the high-voltage side.

According to a thirteenth aspect of the present invention, in the twelfth aspect of the present invention, the input voltage is a voltage across the battery, and when the temperature of the battery is equal to or lower than a predetermined value, the input voltage is stepped down and output. The apparatus further includes a warming-up unit that warms up the battery by alternately repeating the process and the boosting process by the boosting control unit.

  Some batteries have reduced performance at low temperatures. In the above invention, in view of this point, such a situation can be improved by providing the warming-up means under a situation where the performance of the battery is assumed to be lowered due to the low temperature.

(First embodiment)
Hereinafter, a first embodiment in which a power conversion device according to the present invention is applied to a power conversion device for a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The high voltage battery 10 constitutes a high voltage system of the vehicle, and its output voltage is a predetermined high voltage (for example, “288V”). The high voltage battery 10 is an assembled battery configured by connecting a plurality of secondary battery cells such as lithium ion secondary batteries in series. The step-down converter CV steps down the voltage of the high voltage battery 10 and outputs it to the low voltage battery 12. Here, the low voltage battery 12 serves as a power source for supplying electric power to an electric load in the low voltage system of the vehicle, and its output voltage is a predetermined low voltage (for example, “12 V”).

  The step-down converter CV includes transformers Ta and Tb. Each of these transformers Ta and Tb includes a pair of primary side coils T1a and T1b corresponding to one secondary side coil T2a and T2b, respectively. FIG. 2 schematically shows the structure of the transformers Ta and Tb. In FIG. 2, the transformers Ta and Tb are collectively referred to as a transformer T, the primary side coils T1a and T1b are collectively referred to as a primary side coil T1, and the secondary side coils T2a and T2b are collectively referred to as a secondary side coil T2. It is summed up. As shown in the figure, the transformer T has the same closed magnetic circuit generated when a current flows through each of the pair of primary side coils T1, and this is linked by the secondary side coil T2. is there. In other words, the closed magnetic path linked by one secondary coil T2 is shared by the pair of primary coils T1. Incidentally, FIG. 2 exemplifies a configuration in which a pair of primary side coil T1 and secondary side coil T2 are wound around an iron core CF for forming a closed magnetic circuit, and the iron core C includes a gap. However, the iron core CF itself may be a closed loop.

  The step-down converter CV shown in FIG. 1 includes a series connection body of capacitors C1 and C2 connected in parallel to the high-voltage battery 10. And each of these capacitor | condensers C1 and C2 comprises a loop circuit via the primary side coils T1a and T1b. Specifically, here, the primary side coils T1a and T1b constituting the loop circuit corresponding to the capacitor C1 and the primary side coils T1a and T1b constituting the loop circuit corresponding to the capacitor C2 are separate members. Yes. Each of the loop circuits including the capacitors C1 and C2 is opened and closed by the switching elements Q1 and Q2. In the present embodiment, N-channel power MOS field effect transistors are assumed as the switching elements Q1 and Q2. Incidentally, in the figure, the diode connected in parallel between the input terminal (drain) and the output terminal (source) of the switching elements Q1, Q2 is the body diode of the switching elements Q1, Q2.

  The cathodes of the diodes Da and Db are connected to the secondary coils T2a and T2b of the transformers Ta and Tb, respectively. Specifically, the polarity of the voltage induced by the mutual induction between the primary side coils T1a and T1b connected in series is such that the secondary side connected to the terminal of the secondary side coil T2a connected to the diode Da and the diode Db. Diodes Da and Db are connected so as to be opposite to each other at the terminal of the coil T2b. Accordingly, either one of the diodes Da and Db is turned on according to which polarity voltage is applied to the primary side coils T1a and T1b. Therefore, a current can be output from the secondary side of the step-down converter CV regardless of which polarity voltage is applied to the primary side coils T1a and T1b.

  The output voltages of the secondary coils T2a and T2b are applied to the capacitor 14 and the low voltage battery 12.

  The controller 20 operates the operation signals g1 and g2 by outputting the operation signals g1 and g2 to the switching elements Q1 and Q2 of the step-down converter CV, thereby controlling the output voltage of the step-down converter CV.

  In FIG. 3, the operation mode of switching element Q1, Q2 by the control apparatus 20 is shown. Specifically, FIG. 3 (a) shows the transition of the operation mode of the switching element Q1, FIG. 3 (b) shows the transition of the operation mode of the switching element Q2, and FIG. 3 (c) shows the transition of the switching element Q1. The transition of the voltage between the source and the drain is shown, and FIG. 3D shows the transition of the voltage between the source and the drain of the switching element Q2. 3 (e) shows the transition of the current iQ1 flowing through the switching element Q1, FIG. 3 (f) shows the transition of the current iQ2 flowing through the switching element Q2, and FIG. 3 (g) shows the primary side. The transition of the voltage V1a at both ends of the coil T1a is shown, FIG. 3 (h) shows the transition of the voltage V1b at both ends of the primary coil T1b, and FIG. 3 (i) shows the transition of the current iDa flowing through the diode Da. FIG. 3J shows the transition of the current iDb flowing through the diode Db.

As shown in the figure, in the present embodiment, the step-down process is performed by alternately turning on the switching elements Q1 and Q2. Specifically, mode a in which switching element Q1 is turned on, mode b in which both switching elements Q1 and Q2 are turned off, mode c in which switching element Q2 is turned on, and both switching elements Q1 and Q2 are turned off The step-down process is performed by sequentially repeating the four modes d. Hereinafter, a current distribution mode in each mode will be described. In the following description, it is assumed that the transformers Ta and Tb are both tightly coupled transformers.
・ Mode a
In this mode, a current flows through the loop circuit of the capacitor C1, the switching element Q1, and the primary side coils T1b and T1a shown in FIG. Thereby, a counter electromotive voltage in which the switching element Q1 side is positive is generated in the primary side coils T1a and T1b. At this time, the voltage generated in the secondary coil T2b due to the mutual induction is negative at the terminal connected to the cathode side of the diode Db, so that a forward current flows through the diode Db. On the other hand, since the voltage generated in the secondary coil T2a by mutual induction is positive at the terminal connected to the cathode side of the diode Da, no current flows through the diode Da. For this reason, in this mode, energy is output to the capacitor 14 and the low-voltage battery 12 via the transformer Tb. Incidentally, the current flowing through the primary side coil T1b of the transformer Tb is the sum of the exciting current of the transformer Ta and the current released from the exciting inductance of the transformer Tb.
・ Mode b
In this mode, the excitation energy of the transformers Ta and Tb shown in FIG. 1 is released to the load through the secondary coils T2a and T2b of the transformers Ta and Tb.
・ Mode c
In this mode, a current flows through the loop circuit of the capacitor C2, the primary side coils T1a and T1b and the switching element Q2 shown in FIG. As a result, a counter electromotive voltage in which the switching element Q2 side is negative is generated in the primary side coils T1a and T1b. At this time, the voltage generated in the secondary coil T2a by mutual induction is negative at the terminal connected to the cathode side of the diode Da, so that a forward current flows through the diode Da. On the other hand, since the voltage generated in the secondary coil T2b by mutual induction is positive at the terminal connected to the cathode side of the diode Db, no current flows through the diode Db. For this reason, in this mode, energy is output to the capacitor 14 and the low voltage battery 12 via the transformer Ta. Incidentally, the current flowing through the primary coil T1b of the transformer Ta is the sum of the exciting current of the transformer Tb and the current released from the exciting inductance of the transformer Ta.
・ Mode d
In this mode, the excitation energy of the transformers Ta and Tb shown in FIG. 1 is released to the load through the secondary coils T2a and T2b of the transformers Ta and Tb.

  In the present embodiment, the time determined by the modes a to d is the time during which the switching element Q1 is turned on (mode a processing time) and the time during which the switching element Q2 is turned on (mode c processing time). The half cycle of the application cycle is set as the upper limit. In particular, the time when the switching element Q1 is turned on and the time when the switching element Q2 is turned on are made equal to each other. Thereby, the voltage Vc1 of the capacitor C1 and the voltage Vc2 of the capacitor C2 can be made equal. In other words, the voltage (input voltage Vi) of the high voltage battery 10 can be equally divided by the capacitors C1 and C2. This will be described below.

  In mode a, energy is output via the transformer Tb, so that the voltage applied to the primary coil T1b using the output voltage Vo of the step-down converter CV and the turn ratio n of the transformer Tb is “ nVo ". For this reason, the voltage applied to the primary coil T1a is “Vc1-nVo”. On the other hand, in the modes b to d, since the excitation energy of the transformer Ta is output through the secondary coil T2a of the transformer Ta, the voltage of the primary coil T1a is “nVo”. From the condition that the et products of these modes a and modes b to d are equal, the following formula (c1) using the time ratio D of the time of mode a to one cycle of modes a to d is established.

(Vc1-nVo) .D = nVo. (1-D) (c1)
Similarly, the et product of the primary side coil T1b of the transformer Tb is expressed by the following equation (c2). However, in the following, it is assumed that the turns ratio of the transformer Ta is equal to the turns ratio n of the transformer Tb.

(Vc2-nVo) · D = nVo · (1-D) (c2)
From the above equations (c1) and (c2), it can be seen that the voltages Vc1 and Vc2 of the capacitors C1 and C2 are equal to each other (the following equation (c3)).

Vc1 = Vc2 = nVo / D (c3)
On the other hand, since the capacitors C1 and C2 are connected in parallel to the high voltage battery 10, the following equation (c4) is established.

Vc1 + Vc2 = Vi (c4)
In view of the above formula (c3), “Vc1 = Vc2 = Vi / 2” is obtained from the above formula (c4). Further, from the above formulas (c3) and (c4), the processing of the above modes a to d is set as one cycle, and by repeating these, the output voltage Vo of the step-down converter CV is obtained from the time ratio D and the turn ratio n. Depending on the input voltage Vi, “Vo = Vi · D / 2n”.

  Thus, according to the present embodiment, the output voltage Vo can be controlled by manipulating the duty ratio D. Moreover, in the step-down converter CV according to the present embodiment, the maximum voltage applied between the sources and drains of the switching elements Q1, Q2 becomes the input voltage Vi regardless of the time ratio D. Next, this will be described. In the following, in view of the symmetry of operation of the switching elements Q1 and Q2, the maximum voltage applied between the source and drain of the switching element Q1 is derived.

  The period in which the voltage applied between the source and drain of the switching element Q1 is maximum is within the period in which the switching element Q1 is in the off state. During this period, the sum of the voltage Vc1 of the capacitor C1 and the voltages V1a and V1b across the primary coils T1a and T1b is applied between the source and drain of the switching element Q1. Here, in the modes b and d in which the switching elements Q1 and Q2 are turned off, the voltage polarity at the connection point between the primary coil T1a and the primary coil T1b is the same, so the primary side The voltage at both ends of the series connection body of the coils T1a and T1b becomes zero. For this reason, the voltage applied to the switching element Q1 becomes the voltage Vc1 of the capacitor C1. On the other hand, in mode d, since the switching element Q2 is turned on, the voltage across the serial connection of the primary side coils T1a and T1b allocated to the switching element Q2 is the voltage Vc2 (= Vi / 2). Here, each of the primary side coils T1a and T1b allocated to the switching element Q2 and each of the primary side coils T1a and T1b allocated to the switching element Q1 are linked with the same magnetic flux. Therefore, the voltage at both ends of the series connection body of the primary side coils T1a and T1b allocated to the switching element Q1 is also equal to the voltage at both ends of the series connection body of the primary side coils T1a and T1b allocated to the switching element Q2. Become. Therefore, the voltage applied between the source and drain of the switching element Q1 is the sum of the voltage Vc1 of the capacitor C1 and the voltage Vc2 of the capacitor C2, that is, the input voltage Vi.

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

  (1) A voltage obtained by dividing the input voltage can be applied to the primary side coil in two ways in which the polarities of the voltages generated in the secondary side coil of the transformers Ta and Tb are opposite to each other. The switching elements Q1 and Q2 are provided, and the transformers Ta and Tb are provided with a plurality of primary side coils corresponding to one secondary side coil. Here, by applying the divided voltage, the voltage applied between the sources and drains of the switching elements Q1 and Q2 can be suppressed, and as a result, the required breakdown voltage of the switching elements Q1 and Q2 is increased. Can be suppressed. Further, by providing a plurality of primary side coils T1a and primary side coils T1b, the amount of energy handled by each primary side coil T1a, T1b can be reduced.

  (2) The input voltage Vi is divided into an even number (two) by the capacitors C1 and C2. Thereby, while performing the reset process of the magnetic flux of secondary side coil T2a, T2b appropriately, the utilization degree of the some secondary side coil corresponding to one secondary side coil can mutually be made the same.

  (3) In the voltage application period (modes a to d) in which the voltages divided by the capacitors C1 and C2 are applied instead of the primary coils T1a and T1b, the application time (modes) of the divided voltages The switching elements Q1 and Q2 were operated so that the processing time of a and the processing time of mode c were equal to each other. Thereby, since the voltage application process has symmetry, it is easy to make the divided voltage values equal to each other.

  (4) The voltage polarities that allow current to flow between the pair of transformers Ta and Tb in which the primary coils are connected in series to each other and the secondary coils of the pair of transformers Ta and Tb are reversed. Diodes Da and Db. As a result, the condition for equalizing the divided voltage values and the condition for controlling the output voltage Vo (duty ratio D) can be made independent of each other.

  (5) By providing the number of capacitors (capacitors C1 and C2) equal to the number of divisions of the input voltage Vi, the input voltage Vi can be suitably divided.

  (6) The pair of secondary side coils T2a and T2b includes diodes Da and Db for reversing the voltage polarities that enable current flow. As a result, when the divided voltage of the input voltage Vi is applied to the primary side coils T1a and T1b in two ways in which the polarities of the voltages generated in the secondary side coils T2a and T2b are opposite to each other, Depending on whether the partial pressure is applied, it is possible to pass a current through different secondary coils.

  (7) The present invention is applied to the step-down converter CV. As a result, there are few disadvantages caused by a decrease in the output voltage Vo due to the divided input voltage Vi.

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

  FIG. 4 shows a system configuration according to the present embodiment. In FIG. 4, members corresponding to those in FIG. 1 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, the series connection body of the switching elements Q1 and Q2 is connected in parallel to the high voltage battery 10. A loop circuit is constituted by one of the series-connected bodies of the primary side coils T1a and T1b, the capacitor C1, and the switching element Q1, and another loop circuit is formed by the other of the series-connected bodies, the capacitor C2, and the switching element Q2. Configured. Also by this, the same effect as the first embodiment can be obtained.

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

  FIG. 5 shows a system configuration according to the present embodiment. In FIG. 5, members corresponding to those in FIG. 4 are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, the negative electrode of the capacitor C1 and the positive electrode of the capacitor C2 are short-circuited without passing through the primary side coils T1a and T1b. Also by this, the same effect as in the second embodiment can be obtained.

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

  FIG. 6 shows a system configuration according to the present embodiment. In FIG. 6, members corresponding to those in FIG. 1 are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, each of the transformers Ta and Tb includes four primary coils T1a and T1b. On the other hand, in this embodiment, the high voltage battery 10 is connected in parallel to a series connection body of four capacitors C1 to C4. Each of the capacitors C1 to C4 is assigned one of four primary coils T1a and T1b, and a loop circuit including these capacitors C1 to C4 and the corresponding primary coils T1a and T1b, Opened and closed by the corresponding switching elements Q1 to Q4. Incidentally, these switching elements Q1 to Q4 are operated by outputting operation signals g1 to g4 from the control device 20.

  In FIG. 7, the operation mode of switching element Q1-Q4 by the control apparatus 20 concerning this embodiment is shown. Specifically, FIGS. 7 (a) to 7 (d) show transitions of the operation modes of the switching elements Q1 to Q4, and FIGS. 7 (e) to 7 (h) show switching elements. The transition of the voltage between the source and drain of each of Q1 to Q4 is shown, and the transition of the current flowing through each of the switching elements Q1 to Q4 is shown in each of FIGS. 7 (i) to 7 (l).

  As shown in the figure, in this embodiment, the step-down process is performed by sequentially turning on the switching elements Q1, Q2, Q3, and Q4. Specifically, mode a in which only switching element Q1 is turned on, mode b in which all switching elements Q1 to Q4 are turned off, mode c in which only switching element Q2 is turned on, and all switching elements Q1 to Q4 are turned off. Mode d in which only switching element Q3 is turned on, mode f in which all switching elements Q1 to Q4 are turned off, mode g in which only switching element Q4 is turned on, and all switching elements Q1 to Q4 are turned on. The step-down process is performed by sequentially repeating the eight modes of the mode h that are turned off. As a result, reverse polarity voltages are alternately applied to the secondary coils T2a and T2b.

  Here, in the present embodiment, in the voltage application cycle composed of the above modes a to h, the ON times of the switching elements Q1 to Q4 are set to “¼” or less of the voltage application cycle. And the time when each of switching elements Q1-Q4 will be in an ON state is made mutually the same. Thereby, each of the switching elements Q1 to Q4 with respect to a cycle in which any one of the switching devices Q1 to Q4 is turned on twice (a cycle in which the polarity of the applied voltage to the secondary coils T2a and T2b is reversed twice) The relationship of the et product in the period in which the polarity of the voltage applied to the secondary side coils T2a and T2b is reversed twice using the time ratio D of the on-state time is expressed by the above formula (c1 ), (C2). On the other hand, in the modes e to h, the following equations (c5) and (c6) are obtained using the voltages Vc3 and Vc4 of the capacitors C3 and C4.

(Vc3-nVo) · D = nVo · (1-D) (c5)
(Vc4-nVo) · D = nVo · (1-D) (c6)
According to the above equations (c1), (c2), (c3), and (c4), it can be seen that the voltages Vc1 to Vc4 of the capacitors C1 to C4 are equal to each other (the following equation (c7)).

Vc1 = Vc2 = Vc3 = Vc4 = nVo / D (c7)
In view of “Vc1 + Vc2 + Vc3 + Vc4 = Vi”, the following equation (c8) is established.

Vc1 = Vc2 = Vc3 = Vc4 = Vi / 4 (c8)
It can also be seen that the output voltage is “Vi · D / 4n”.

  Here, the maximum voltage applied to each of the switching elements Q1 to Q4 is the same as the polarity of the corresponding capacitors C1 to C4 when they are in the off state and the voltage of the series connection body of the primary side coils T1a and T1b. Therefore, “(Vi / 4) × 2 = Vi / 2”. Thus, according to this embodiment, the voltage applied between the source and drain of each switching element Q1-Q4 can be reduced further.

(Fifth embodiment)
Hereinafter, the fifth embodiment will be described with reference to the drawings with a focus on differences from the fourth embodiment.

  FIG. 8 shows a system configuration according to the present embodiment. In FIG. 8, members corresponding to those in FIG. 6 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, the series connection body of the switching elements Q <b> 1 to Q <b> 4 is connected in parallel to the high voltage battery 10. Then, each of the switching element Q1 and the capacitor C1, the switching element Q2 and the capacitor C2, the switching element Q3 and the capacitor C3, the switching element Q4 and the capacitor C4, and a series connection body of the primary side coils T1a and T1b allocated to them. A loop circuit was constructed. Also by this, the same effect as in the fourth embodiment can be obtained.

(Sixth embodiment)
Hereinafter, the sixth embodiment will be described with reference to the drawings with a focus on differences from the fourth embodiment.

  FIG. 9 shows a system configuration according to the present embodiment. In FIG. 9, members corresponding to those in FIG. 6 are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, primary coils T1a and T1b that form a loop circuit with the switching element Q1 and the capacitor C1, and primary coils T1a and T1a that form a loop circuit with the switching element Q2 and the capacitor C2, The primary side coils T1a and T1b constituting the loop circuit together with the switching element Q3 and the capacitor C3 are the same member, and the primary side coils T1a and T1b constituting the loop circuit together with the switching element Q4 and the capacitor C4 are the same. It was set as a member. Also by this, an effect according to the effect of the fourth embodiment can be obtained.

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

  FIG. 10 shows a system configuration according to the present embodiment. In FIG. 10, members corresponding to those in FIG. 1 are given the same reference numerals for convenience.

  As illustrated, the present embodiment includes a single transformer T. The transformer T includes two secondary coils T2a and T2b corresponding to the pair of primary coils T1. Here, the secondary side coils T2a and T2b must be linked to the closed magnetic circuit generated by the current flowing through the pair of primary side coils T1, but the chain of the secondary side coil T2a is not different. The closed magnetic circuit that intersects and the closed magnetic circuit that links the secondary coil T2b are different from each other. As this transformer T, what is described in FIG. 7 etc. of Unexamined-Japanese-Patent No. 2003-79142 is assumed, for example.

  In the present embodiment, the switching elements Q1 and Q2 are turned on and off in a complementary manner. That is, a periodic operation including a process of turning on the switching element Q1 and turning off the switching element Q2 and a process of turning off the switching element Q1 and turning on the switching element Q2 is performed. By using the time ratio D of the time during which the switching element Q1 is turned on with respect to one period of this periodic operation, the capacitor of the capacitor can be obtained by using the relation of the et product as in the derivation of the above expressions (c1) and (c2). The voltages Vc1 and Vc2 of C1 and C2 are “Vi (1-D)” and “ViD”, respectively.

  Therefore, also in this case, the maximum value of the voltage applied between the sources and drains of the switching elements Q1 and Q2 is the input voltage Vi.

  According to this embodiment described above, it is possible to obtain the effects according to the above (1), (2), (5) to (7) of the first embodiment.

(Eighth embodiment)
Hereinafter, the eighth embodiment will be described with reference to the drawings with a focus on differences from the previous seventh embodiment.

  FIG. 11 shows a system configuration according to the present embodiment. In FIG. 11, members corresponding to those in FIG. 10 and the like are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, the transformer T includes four primary coils T1. On the other hand, in this embodiment, the high voltage battery 10 is connected in parallel to a series connection body of four capacitors C1 to C4. Each of the capacitors C1 to C4 is assigned one of the four primary coils T1, and the loop circuit including the capacitors C1 to C4 and the corresponding primary coil T1 includes a corresponding switching element. Opened and closed by Q1-Q4. Incidentally, these switching elements Q1 to Q4 are operated by outputting operation signals g1 to g4 from the control device 20.

  In the present embodiment, the switching elements Q1 to Q4 are turned on once each in one cycle, and any one of the switching elements Q1 to Q4 at any timing of the one cycle (excluding the dead time). Ensure that only one is on. Specifically, the switching elements Q1, Q2, Q3, and Q4 are turned on in this order, and the ON times of the switching elements Q1 and Q3 are set equal to the ON times of the switching elements Q2 and Q4. Accordingly, assuming that the et products in the period in which the switching elements Q1 to Q4 are turned on twice are equal to each other, using the time ratio D of the on-time of each switching element Q1, Q3 with respect to the half cycle of the voltage application period, The ratio “Vc1: Vc2: Vc3: Vc4” of the voltages Vc1 to Vc4 of the capacitors C1 to C4 is “1: D / (1-D): 1: D / (1-D)”. The sum of the voltages Vc1 to Vc4 of the capacitors C1 to C4 is the input voltage Vi.

  For this reason, for example, the maximum voltage applied between the source and drain of the switching element Q1 is “Vc1 + Vc2” or “Vc1 + Vc4”, which is smaller than the input voltage Vi. Based on the same consideration, the maximum voltage applied between the source and drain of the switching elements Q2 to Q4 is also smaller than the input voltage Vi. Therefore, the voltage applied between the sources and drains of the switching elements Q1 to Q4 can be suppressed also in this embodiment.

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

  FIG. 12 shows the system configuration of this embodiment. In FIG. 12, members corresponding to those shown in FIG. 1 are given the same reference numerals for the sake of convenience.

  In this embodiment, switching means Q3, Q4 are used instead of the diodes Da, Db as means for reversing the voltage polarities that allow current flow between the pair of secondary coils T2a, T2b. Prepare. Here, MOS field effect transistors are assumed as the switching elements Q3 and Q4. Thereby, compared with the case where diode Da, Db is used, reduction of a power loss becomes easy.

  Furthermore, according to the present embodiment, energy can be discharged from the low voltage battery 12 to the high voltage battery 10 by reversing the input side and the output side separately from the original application. Here, in the step-down converter CV, the voltage applied to the primary side coils T1a and T1b is originally determined by the voltage of the low voltage battery 12 and the turn ratio n of the transformers Ta and Tb. Unless the voltage is higher than the value obtained by dividing the voltage of the high voltage battery 10 by the turn ratio n, the energy cannot be released from the low voltage battery 12 side to the high voltage battery 10 side. However, in the present embodiment, energy can be released from the low voltage battery 12 side to the high voltage battery 10 side by boosting the voltage of the low voltage battery 12 in the following manner.

  FIG. 13 shows a boost control mode according to this embodiment. Specifically, FIG. 13A shows the transition of the state of the switching element Q3, FIG. 13B shows the transition of the state of the switching element Q4, and FIG. 13C shows the state of the switching element Q1. FIG. 13D shows the transition of the state of the switching element Q2.

  As illustrated, the boost control is performed by turning on both of the secondary side switching elements Q3 and Q4 in the original application and then turning off one of them. Here, the period during which both of the switching elements Q3 and Q4 are turned on is provided to accumulate energy in the secondary coils T2a and T2b. That is, when both the switching elements Q3 and Q4 are turned on, the voltage induced in the primary coil T1a due to the current flowing in the secondary coil T2a and the current flows in the secondary coil T2b. As a result, the voltage induced in the primary side coil T1b cancels out, so that energy is not released through the primary side coils T1a and T1b during this period, and energy is not supplied to the secondary side coils T2a and T2b. Can be stored. After energy is stored in the secondary side coils T2a and T2b in this way, one of the switching elements Q3 and Q4 is turned off, so that the corresponding primary side coil is passed through the secondary side coil corresponding to the other side. It becomes possible to release energy. For this reason, the switching element on the primary side is turned on so as to make the loop circuit including the corresponding primary side coil into a closed loop. As a result, the voltage on the low voltage side (secondary side in the original application) can be boosted and applied to the high voltage side (primary side in the original application).

  Specifically, as shown in FIG. 13, a period in which only the switching element Q3 is turned on and a period in which only the switching element Q4 is turned on are alternately generated. This is a setting for resetting the magnetic field of the primary side coils T1a and T1b.

  By performing the boost control, when the remaining capacity of the low voltage battery 12 is excessive and the remaining capacity on the high voltage battery 10 side is insufficient, energy can be supplied from the low voltage battery 12 to the high voltage battery 10. . Furthermore, by using the above boost control, the high voltage battery 10 and the low voltage battery 12 can be warmed up quickly and the situation can be quickly resolved under the condition that the performance of the high voltage battery 10 and the low voltage battery 12 is excessively lowered. it can.

  FIG. 14 shows a procedure for warming up the high-voltage battery 10. This process is repeatedly executed by the control device 20 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, it is determined whether or not there is a request for warm-up of the high-voltage battery 10. This process may be, for example, a process in which temperature detection means is provided in the vicinity of the high voltage battery 10 and it is determined whether or not the detected value is equal to or lower than a predetermined temperature. When an affirmative determination is made in step S10, the step-up converter CV performs the step-up process for a predetermined time (steps S12 and S14). After that, a step-down process that is a normal process by the step-down converter CV is performed for a predetermined time (steps S16 and S18). When this process is completed, it is determined in step S20 whether or not the high-voltage battery 10 has been warmed up. This process may be, for example, a process in which temperature detection means is provided in the vicinity of the high voltage battery 10 and it is determined whether or not the detected value is equal to or lower than a predetermined temperature. Note that, from the viewpoint of avoiding the hunting of the execution and stop of the warm-up process, it is desirable that the predetermined temperature in step S20 is higher than the predetermined temperature in step S10. If a negative determination is made in step S20, the process returns to step S12. On the other hand, when an affirmative determination is made in step S20 or a negative determination is made in step S10, this series of processes is temporarily terminated.

  According to such a series of processes, when a current flows through the high-voltage battery 10, the high-voltage battery 10 can be warmed up by heat generated when the current flows through the internal resistance in the high-voltage battery 10.

  According to the embodiment described above in detail, the following effects can be obtained in addition to the effects according to the above-described effects of the first embodiment.

  (8) By providing the switching elements Q3 and Q4, the current flowing through the secondary coils T2a and T2b can be rectified.

  (9) By operating the switching elements Q3 and Q4, a process for making both of the loop circuits constituting the secondary side coils T2a and T2b into a closed loop, a process for making one closed loop, a process for making both closed loops, and Boosting control was performed by periodically repeating the process of making the other closed loop. Thereby, energy can be supplied from the low voltage battery 12 side to the high voltage battery 10 side separately from the original use of the step-down converter CV.

  (10) A process for warming up the high-voltage battery 10 was performed by alternately repeating the step-down process and the step-up process. Thereby, such a situation can be improved under a situation where the performance of the high-voltage battery 10 is assumed to deteriorate due to the low temperature.

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

  FIG. 15 shows a system configuration diagram according to the present embodiment. In FIG. 15, members corresponding to those shown in FIG. 1 are given the same reference numerals for the sake of convenience.

  As illustrated, in the present embodiment, each of the transformers Ta and Tb includes three primary coils T1a and T1b. On the other hand, in this embodiment, the high voltage battery 10 is connected in parallel to a series connection body of three capacitors C1 to C3. Each of the capacitors C1 to C3 is assigned one of three primary coils T1a and T1b, and a loop circuit including these capacitors C1 to C3 and the corresponding primary coils T1a and T1b, Opened and closed by corresponding switching elements Q1 to Q3. Incidentally, these switching elements Q1 to Q3 are operated by outputting operation signals g1 to g3 from the control device 20.

  In FIG. 16, the operation aspect of switching element Q1-Q3 by the control apparatus 20 concerning this embodiment is shown. Specifically, FIG. 16A to FIG. 16C show the transition of the operation modes of the switching elements Q1 to Q3.

  As shown in the figure, in this embodiment, the step-down process is performed by turning on the switching elements Q1, Q2, and Q3 instead. Specifically, mode a in which only switching element Q1 is turned on, mode b in which all switching elements Q1 to Q3 are turned off, mode c in which only switching element Q2 is turned on, and all switching elements Q1 to Q3 are turned off. Mode d in which only switching element Q3 is turned on, mode f in which all switching elements Q1 to Q3 are turned off, mode g in which only switching element Q2 is turned on, and all switching elements Q1 to Q3 are turned on. The step-down process is performed by sequentially repeating the eight modes of the mode h that are turned off. Thus, also in this embodiment, switching is performed so that the magnetic fluxes of the secondary coils T2a and T2b are reset at every cycle in which the switching state of the switching elements Q1 to Q3 is switched twice (“1/3” of the step-down cycle). Operate elements Q1-Q3.

  Here, also in the present embodiment, each one ON time in one cycle of the step-down process is made equal to each other. Thus, it is understood that the voltages Vc1 to Vc3 of the capacitors C1 to C3 are equal to each other using the et product relationship for each of the modes a to d and the modes e to h. For this reason, in this embodiment, since the maximum value of the voltage applied between the source and drain of each switching element Q1 to Q3 is “Vi / 3”, the maximum value is made smaller than the input voltage Vi. Can do.

(Eleventh embodiment)
Hereinafter, the eleventh embodiment will be described with reference to the drawings, centering on differences from the first embodiment.

  FIG. 17 shows a system configuration diagram according to the present embodiment. In FIG. 17, members corresponding to those shown in FIG. 1 are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, the capacitor C2 is deleted. Even in this case, by performing the step-down processing in the manner shown in FIG. 3, the relationship between the output voltage Vo and the duty ratio D, or between the sources and drains of the switching elements Q1 and Q2 is applied. The voltage is the same as in the first embodiment. This is because, when the voltage applied to the series connection body of the primary side coils T1a and T1b when the switching element Q2 is in the on state is the voltage Vc2, the above formulas (c1) and (c2) are established as they are, Furthermore, since “Vc1 + Vc2 = Vi”, the derivation of the above formula (c3) can be applied as it is.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) and (3) to (7) of the first embodiment.

  (11) By adopting a configuration in which the capacitor C2 is deleted in the first embodiment, the number of parts can be reduced.

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

  FIG. 18 shows a system configuration diagram according to the present embodiment. In FIG. 18, members corresponding to those shown in FIG. 6 are given the same reference numerals for convenience.

  In the present embodiment, the capacitor C4 is deleted from the configuration shown in FIG. Even in this case, by performing the step-down process in the manner shown in FIG. 7, the relationship between the output voltage Vo and the duty ratio D, or between the sources and drains of the switching elements Q1 to Q4 is applied. The voltage is the same as in the fourth embodiment. The reason for this can be considered in the previous eleventh embodiment in the same manner as the reason why the same embodiment is the same as the first embodiment.

(13th Embodiment)
Hereinafter, a thirteenth embodiment will be described with reference to the drawings, centering on differences from the fourth embodiment.

  FIG. 19 shows a system configuration diagram according to the present embodiment. In FIG. 19, members corresponding to those shown in FIG. 6 are given the same reference numerals for the sake of convenience.

  In the present embodiment, the capacitors C2 and C4 are deleted from the configuration shown in FIG. In this case, it is necessary to provide a period during which the switching elements Q2 and Q4 are simultaneously turned on. For this reason, in this embodiment, a pressure | voltage reduction process is performed in the aspect shown in FIG.

  FIG. 20 shows an operation mode of the switching elements Q1 to Q4 by the control device 20 according to the present embodiment. Specifically, each of FIG. 20A to FIG. 20D shows a transition of each operation mode of the switching elements Q1 to Q4.

  As shown in the figure, in this embodiment, mode a in which only switching element Q1 is turned on, mode b in which all switching elements Q1 to Q4 are turned off, and mode c in which only switching elements Q2 and Q4 are turned on. Mode d in which all switching elements Q1 to Q4 are turned off, mode e in which only switching element Q3 is turned on, mode f in which all switching elements Q1 to Q4 are turned off, and only switching elements Q2 and Q4 are turned on The step-down process is performed by sequentially repeating the eight modes, i.e., mode g and mode h in which all switching elements Q1 to Q4 are turned off.

  Here, the polarity of the voltage applied to the secondary coils T2a and T2b is alternately reversed. This is a setting for resetting the magnetic flux induced in the secondary coils T2a and T2b. Also in this embodiment, the times of modes a, c, e, and g are made equal to each other. As a result, the maximum value of the voltage applied between the source and drain of the switching elements Q1 to Q4 is the same as that of the fourth embodiment. This is because the voltages applied to the primary side transformers T1a and T1b in the modes c and g are the same as those in the fourth embodiment.

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

  FIG. 21 shows a system configuration diagram according to the present embodiment. In FIG. 21, members corresponding to those shown in FIG. 1 are given the same reference numerals for the sake of convenience.

  As shown in the figure, in this embodiment, the capacitors C1 and C2 are deleted, and each of the switching elements Q1 and Q2 is configured by a series connection body of the corresponding primary side coils T1a and T1b. The same number of battery cells in the high-voltage battery 10 are allocated to each of the loop circuits. Here, the battery cells have the same specifications.

  In such a configuration, by performing the same processing as in the first embodiment, the voltage of the battery cell allocated to each loop circuit can be made the same, so that the remaining capacity of each battery cell is made substantially equal. Can do. This is because battery cells of the same specification basically have a one-to-one correspondence between the remaining capacity and the terminal voltage. For this reason, it is possible to equalize the remaining capacities of the same number of battery cells by equalizing the voltages of the same number of battery cells by the step-down process described in the first embodiment. For this reason, the dispersion | variation in the remaining capacity between battery cells can be suppressed to the extent of the dispersion | variation between several battery cells in a loop circuit.

  According to the present embodiment described above, the following effects can be obtained in addition to the effects according to the above-described effects of the first embodiment.

  (12) The input voltage Vi was divided by extracting the electrode voltage of the intermediate battery cell constituting the high-voltage battery 10. Thereby, it is possible to suitably divide the input voltage while suppressing or avoiding the addition of new hardware means.

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

  -You may change the said 5th Embodiment by the change of the said 6th Embodiment with respect to the said 4th Embodiment.

  -You may change 2nd, 3rd embodiment by the change of the said 7th Embodiment with respect to the said 1st Embodiment.

  -You may change the said 5th, 6th embodiment by the change of the 8th Embodiment with respect to the said 4th Embodiment.

  -You may change the said 2nd-8th embodiment by the change of the 9th Embodiment with respect to the said 1st Embodiment.

  -You may change the said 2nd, 3rd, 9th embodiment by the change of the 11th Embodiment with respect to the said 1st Embodiment.

  In the twelfth embodiment, the capacitor C4 is deleted from the step-down converter CV in the fourth embodiment. However, the present invention is not limited to this, and any one of the capacitors C1 to C3 may be deleted.

  -You may change the said 5th, 6th, 8th embodiment by the change of the said 12th Embodiment with respect to the said 4th Embodiment.

  In the tenth embodiment, as in the eleventh and twelfth embodiments, any one of the capacitors C1 to C3 may be deleted.

  -You may change 5th, 6th, 8th embodiment by the change of 13th Embodiment with respect to 4th Embodiment.

  In the twelfth embodiment, the number of divisions of the input voltage is not limited to 4, and may be 5 or more, for example.

  In the thirteenth embodiment, the number of divisions of the input voltage is not limited to 4, and may be 5 or more, for example. In this case, a capacitor may be connected in parallel to every other switching element Q1, Q2,. However, the present invention is not limited to this. In a configuration in which every other capacitor is connected in parallel, the capacitor may be further connected in parallel to any one of the switching elements not connected in parallel.

  The fourth embodiment is different from the first embodiment in that the number of divisions of the input voltage Vi is doubled, but the even number of divisions is not limited thereto. If the number of divisions is “k” and the switching elements are operated symmetrically, the output voltage Vo can be set to “Vi · D / k · n”, and the sources and drains of the switching elements Q1, Q2,. The maximum voltage applied between them can be “2 Vi / k”. However, at this time, as a transformer constituting the step-down converter CV, a pair of transformers in which primary coils are connected in series with each other and a voltage polarity that allows current flow between the secondary coils are used. It is desirable to provide means for reversing each other.

  The step-down converter CV is not limited to one in which the division number of the input voltage Vi is 3 or an arbitrary even number. In general, it may be any integer of 2 or more. However, at this time, the switching elements Q1, Q2,... Are operated so that the divided voltage is applied to the primary coil so that the polarity of the voltage applied to the secondary coil of the transformer is alternately reversed. Is desirable. At this time, as exemplified in each of the above embodiments, the operation pattern is not limited to be set so that the cycle of the operation pattern of the switching elements Q1 and Q2 is as short as possible. That is, for example, in the previous tenth embodiment, instead of the operation pattern shown in FIG. 16, a pattern that becomes the switching elements Q1, Q2, Q3, Q2, Q3, Q2, Q1 may be adopted.

  In the sixth embodiment, the example in which the series connection body of the primary side coils T1a and T1b is shared between the adjacent loop circuits of potentials for the division number of 4 is shown. Is not limited to “4” and may be any integer greater than “3”.

  In the ninth embodiment, when it is determined that the high-voltage battery 10 has a warm-up request, the step-up converter CV is first operated to perform the step-up process. However, the present invention is not limited to this, and the step-down process may be started. .

  In the ninth embodiment, whether or not there is a warm-up request for the low-voltage battery 12 is determined, and if it is determined that there is a warm-up request, the processes of steps S12 to S18 shown in FIG. 14 are performed. Also good. At this time, first, the step-down converter CV may be operated to perform step-down processing.

  The previous second to thirteenth embodiments may be changed according to the changes of the fourteenth embodiment relative to the first embodiment. At this time, when the step-down converter CV according to the second to sixth, ninth, and tenth embodiments is used, the step-down processing mode may be changed. Here, when each battery cell is of the same specification, from the viewpoint of equalizing the remaining capacity and terminal voltage of each battery cell, each voltage cell is proportional to each partial pressure value assumed to be generated by the step-down process. It is desirable to allocate the number of battery cells in the loop circuit for applying the partial pressure.

  However, even when the battery cells constituting the high-voltage battery 10 are not of the same specification, the divided voltage value that is assumed to be generated by the step-down process in equalizing the remaining capacity and the terminal voltage of each battery cell. It is desirable to determine the number of battery cells according to the above.

  In each of the above embodiments, the polarity of the voltage applied to the secondary coil is reversed each time so that the magnetic flux of the secondary coil is reset every time the switching element is turned on twice. Not limited to this. For example, in the first embodiment, by periodically turning on the switching elements Q1, Q1, Q2, and Q2, the magnetic flux of the secondary coil is reset every time the switching element is turned on four times. You may make it do.

  In each of the above embodiments, one cycle is equally divided according to the number of times the switching element is turned on in the voltage application cycle, and each divided time is set as the upper limit of one on operation, but this is not restrictive. For example, as in the previous tenth embodiment, the number of primary coils for applying a voltage of one polarity of a secondary coil and the number of primary coils for applying a voltage of the other polarity If the number is different, it is effective not to set the maximum ON operation time of each switching element to the equally divided time. That is, each of the switching elements Q1, Q2, Q3 is appropriately reset in order to appropriately reset the magnetic flux of the secondary coil despite the fact that each switching element is turned on only once within one cycle of the switching pattern. It is also conceivable that the ratio of the time ratio is “1: 2: 1”. In this case, twice the time obtained by dividing one cycle into four times is the maximum ON operation time of the switching element Q2.

  In each of the above embodiments, the power MOS field effect transistor is used as the primary side switching element. However, the present invention is not limited to this, and may be, for example, an insulated gate bipolar transistor.

  The step-down converter CV is not limited to being mounted on a hybrid vehicle, and may be mounted on an electric vehicle, for example. Furthermore, it is not limited to an in-vehicle converter.

1 is a system configuration diagram according to a first embodiment. FIG. The perspective view which shows the structure of the trans | transformer concerning the embodiment. The time chart which shows the operation mode of the converter concerning the embodiment. The system block diagram concerning 2nd Embodiment. The system block diagram concerning 3rd Embodiment. The system block diagram concerning 4th Embodiment. The time chart which shows the operation mode of the converter concerning the embodiment. The system block diagram concerning 5th Embodiment. The system block diagram concerning 6th Embodiment. The system block diagram concerning 7th Embodiment. The system block diagram concerning 8th Embodiment. The system block diagram concerning 9th Embodiment. The time chart which shows the pressure | voltage rise operation | movement aspect concerning the embodiment. The flowchart which shows the procedure of the warming-up process of the pressure | voltage fall converter concerning the embodiment. The system block diagram concerning 10th Embodiment. The time chart which shows the operation mode of the converter concerning the embodiment. The system block diagram concerning 11th Embodiment. The system block diagram concerning 12th Embodiment. The system block diagram concerning 13th Embodiment. The time chart which shows the operation mode of the converter concerning the embodiment. The system block diagram concerning 14th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... High voltage battery, 20 ... Control apparatus, C1, C2, C3, C4 ... Capacitor, CV ... Step-down converter, Q1, Q2, Q3, Q4 ... Switching element.

Claims (13)

In a power converter that converts a voltage applied to a primary coil of a transformer into a predetermined voltage via a secondary coil and outputs the voltage,
A voltage applying means for applying a voltage obtained by dividing the input voltage to the primary side coil in two ways such that the polarities of the voltages generated in the secondary side coil of the transformer are opposite to each other; Prepared,
The transformer includes a plurality of primary side coils corresponding to one secondary side coil ,
The power conversion device according to claim 1 , wherein the voltage application means sets the division number of the input voltage to 3 or more . It said voltage applying means according to claim 1 Symbol placement of the power converter, characterized in that an even number of divisions of the input voltage. Means for operating the voltage application means so that application times of the divided voltages are equal to each other in a voltage application cycle in which the divided voltages are applied instead of the primary coil; power converter according to claim 1 or 2 wherein, characterized in that it comprises. The transformer includes a pair of transformers in which primary coils are connected in series with each other,
The electric power according to any one of claims 1 to 3 , further comprising means for reversing the voltage polarities that allow current flow between the secondary coils of the pair of transformers. Conversion device. The voltage application means includes a number of capacitors equal to the number of divisions of the input voltage, and allows voltage between both electrodes of the capacitor to be applied to the primary coil. Item 5. The power conversion device according to any one of Items 1 to 4 . The voltage application means includes a capacitor whose number is one smaller than the number of divisions of the input voltage, and subtracts the voltage between both electrodes of the capacitor and the sum of the voltages between both electrodes of the capacitor from the input voltage. the voltage and the power conversion apparatus according to any one of claims 1 to 4, characterized in that each enabling applied to the primary coil. The input voltage is a voltage at both ends of an assembled battery that is a series connection body of battery cells,
Said voltage applying means, the battery pack by extracting the intermediate electrode voltage of the battery cells constituting the power conversion according to any one of claims 1 to 4, characterized in that dividing the input voltage apparatus. The secondary coil of the transformer includes a pair of secondary coils,
The electric power according to any one of claims 1 to 7 , further comprising a rectifier for reversing voltage polarities that allow current flow between the pair of secondary coils. Conversion device. The secondary coil of the transformer includes a pair of secondary coils,
The power converter according to any one of claims 1 to 8 , further comprising opening / closing means for opening / closing each of a pair of loop circuits including each of the pair of secondary coils. Voltage the output power converter according to any one of claims 1 to 9, characterized in that the lower than the input voltage. The voltage applying means for alternately applying a voltage obtained by dividing the input voltage to the primary coil of the transformer in two ways so that the polarities of the voltages generated in the secondary coil of the transformer are opposite to each other. power converter according to any one of claims 1 to 10, further comprising means for manipulating. The output voltage is lower than the input voltage,
By operating the opening / closing means, a process for making both of the pair of loop circuits a closed loop, a process for making one of the pair of loop circuits a closed loop, a process for making the both closed loop, and the loop circuit 10. The power conversion according to claim 9 , further comprising boosting control means for performing a process of boosting and outputting a voltage on the output side to the input voltage side by periodically repeating a process of making the other of the closed loops. apparatus. The input voltage is the voltage across the battery,
When the temperature of the battery is equal to or lower than a predetermined value, a warming-up unit for warming up the battery is further obtained by alternately repeating a process of stepping down and outputting the input voltage and a boosting process by the boosting control unit. The power conversion device according to claim 12, further comprising:

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