JP2017034959A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device capable of increasing power supply efficiency while curbing deterioration and damage of a switching element constituting a circuit.SOLUTION: A power conversion device comprises: a choke coil L13 installed between a power conversion circuit 10 and a direct current power supply 100; an auxiliary coil L14 which is connected in parallel to an output side circuit so that the choke coil L13 functions as a flyback transformer, magnetically connected to the choke coil L13, and wound in a direction to allow exciting current to flow from a negative electrode side of the output side circuit to a positive electrode side thereof when the exciting current flows in the choke coil L13 from the positive electrode side of the direct current power supply 100 to the negative electrode side thereof; and a rectifier cell D1 which is serially connected to the auxiliary coil L14 and shuts off a power supply from the direct current power supply 100 to the output side through the auxiliary coil L14 and the power supply from the output side to an input side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device.

  There is a power supply control device described in Patent Document 1 that outputs electric power supplied from a DC power supply connected to the input side via a transformer. The power supply control device described in Patent Document 1 includes a main power storage device, a capacitive load connected between the power lines of the main power storage device, and a capacitive load between the power lines of the main power storage device via a bidirectional converter. And an auxiliary power storage device connected in parallel. Power transfer between the main power storage device and the auxiliary power storage device is performed using a bidirectional converter. Further, by supplying the power of the auxiliary power storage device to the capacitive load using the bidirectional converter, charging is performed until the voltage of the capacitive load becomes equal to the voltage of the main power storage device.

JP 2007-295699 A

  When the bidirectional converter in the power supply control device described in Patent Document 1 includes a choke coil on the auxiliary battery, the charging to the capacitive load is performed by repeatedly increasing and decreasing the current of the choke coil. Done. Further, the power supply control device described in Patent Document 1 is not provided with a limiting resistor or the like for preventing an inrush current from the viewpoint of cost reduction and miniaturization of the system.

  Here, the condition for reducing the current of the choke coil is that the voltage of the auxiliary storage battery is smaller than the value obtained by dividing the voltage of the capacitive load by the turn ratio of the coils constituting the bidirectional converter. Therefore, when the voltage of the capacitive load is small, such as at the start of charging, the choke coil current continues to increase. As a result, the DCDC converter may be deteriorated or damaged. On the other hand, if the switching element is turned OFF in order to reduce the current of the choke coil, a back electromotive force is generated by the avalanche current, and the switching element may be deteriorated or damaged.

  The present invention has been made to solve the above-mentioned problems, and its main object is to convert power that can improve power supply efficiency while suppressing deterioration and breakage of switching elements constituting the circuit. To provide an apparatus.

  The present invention supplies power from an input side to which a DC power source is connected to a circuit on an output side through a power conversion circuit including a transformer and a switching element including a first coil and a second coil that are magnetically coupled. A choke coil provided between the power conversion circuit and the DC power supply, and the choke coil connected in parallel to the output-side circuit to function as a flyback transformer, the choke Coiled magnetically with the coil, and when the excitation current flows from the positive electrode side to the negative electrode side of the DC power supply to the choke coil, the coil is wound in the direction in which the excitation current flows from the negative electrode side to the positive electrode side of the output side circuit. Auxiliary coil, connected in series with the auxiliary coil, power supply from the DC power source to the output side via the auxiliary coil, and from the output side And a rectifying element for blocking the supply of power to the fill power side.

  With the above configuration, when control is performed so as to include a period in which the supply of power from the DC power supply is cut off, the avalanche current generated in the circuit is supplied to the output side via the auxiliary coil. Therefore, it is possible to suppress deterioration and damage of the input side circuit due to the avalanche current. Furthermore, the power remaining in the input side circuit can be supplied to the output side. Therefore, it is possible to further improve the power supply efficiency to the output side while suppressing deterioration and damage of the input side circuit.

It is a circuit diagram of a power converter. It is a time chart which shows the control in a 1st mode. It is a figure which shows the electric current path | route in 1st mode. It is a figure explaining transition of control in the 1st mode. It is a time chart which shows the control in 2nd mode. It is a figure which shows the electric current path | route in 2nd mode. It is a time chart which shows the control in a 3rd mode. It is a figure which shows the electric current path | route in 3rd mode. It is a flowchart which shows the process which a control part performs. It is a time chart which shows control in the 3rd mode in a 2nd embodiment. It is a control block diagram which shows the process which the control part in 2nd Embodiment performs. It is a circuit diagram of the power converter device in 3rd Embodiment. It is a time chart which shows control in the 1st mode in a 3rd embodiment. It is a time chart which shows control in the 2nd mode in a 3rd embodiment. It is a time chart which shows the control in the 3rd mode in a 3rd embodiment. It is a circuit diagram of the power converter device in 4th Embodiment. It is a time chart which shows the control in the 1st mode in 4th Embodiment. It is a time chart which shows the control in the 2nd mode in 4th Embodiment. It is a time chart which shows control in the 3rd mode in a 4th embodiment. It is a time chart which shows control in the 1st mode in a 5th embodiment. It is a control block diagram which shows the process which the control part in 5th Embodiment performs. It is a control block diagram which shows the process which the control part in 6th Embodiment performs. It is a time chart which shows control in the 1st mode in a 7th embodiment. It is a figure which shows another example of a power converter device. It is a figure which shows another example of a power converter device. It is a figure which shows another example of a power converter device. It is a figure which shows another example of a power converter device. It is a figure which shows another example of control of a 1st mode. It is a figure which shows another example of control of a 2nd mode.

  Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

<First Embodiment>
The power conversion device according to the present embodiment is mounted on a hybrid car including a secondary battery such as a lead battery having a nominal voltage of 12V and a high voltage storage battery such as a lithium ion battery having a nominal voltage of several hundred volts. Is.

  FIG. 1 is a circuit diagram of the power conversion device according to the present embodiment. The power conversion device according to the present embodiment supplies power of the secondary battery 100 that is a DC power source connected to the input side via the power conversion circuit 10 to the output side.

  The power conversion circuit 10 includes a transformer Tr11 and first to sixth switching elements Q11 to Q16 which are MOSFETs. The transformer Tr11 includes a first coil L11 and a second coil L12 that are magnetically coupled to each other, and the first coil L11 has a center tap. The number of turns of the second coil L12 is N / 2 times the number of turns of the first coil L11. That is, the number of turns of the second coil L12 is N times the number of turns from any one end of the first coil L11 to the center tap.

  Both ends of the first coil L11 are connected to the drain of the first switching element Q11 and the drain of the second switching element Q12, respectively. On the other hand, the source of the first switching element Q11 and the source of the second switching element Q12 are connected.

  The secondary battery 100 is connected to the power conversion circuit 10 via the choke coil L13. Specifically, one end of the choke coil L13 is connected to the positive electrode of the secondary battery 100, and the other end of the choke coil L13 is connected to the center tap of the first coil L11. On the other hand, the connection point between the source of the first switching element Q11 and the source of the second switching element Q12 is connected to the negative electrode of the secondary battery 100. A capacitor 101 is connected in parallel to the secondary battery 100.

  One end of the second coil L12 is connected to the source of the third switching element Q13 and the drain of the fourth switching element Q14. The other end of the second coil L12 is connected to the source of the fifth switching element Q15 and the drain of the sixth switching element Q16. The drain of the third switching element Q13 and the drain of the fifth switching element Q15 are connected to the positive output terminal 200a, and the source of the fourth switching element Q14 and the source of the sixth switching element Q16 are the negative output terminal 200b. It is connected to the. A capacitor 201 is connected in parallel to the positive output terminal 200a and the negative output terminal 200b.

  The power converter further includes an auxiliary coil L14 that is magnetically coupled to the choke coil L13. The choke coil L13 and the auxiliary coil L14 constitute a second transformer Tr12 that functions as a flyback transformer. The auxiliary coil L14 is connected in parallel to the power conversion circuit 10, and is connected to the positive output terminal 200a and the negative output terminal 200b.

  The auxiliary coil L14 is wound in a direction in which the excitation current flows from the negative electrode side to the positive electrode side of the circuit on the output side when the excitation current flows through the choke coil L13 from the positive electrode side to the negative electrode side of the secondary battery 100. . The turn ratio between the auxiliary coil L14 and the choke coil L13 is N: 1. In addition, a diode D1 is connected in series to the negative output terminal 200b side of the auxiliary coil L14. When a voltage is applied from the positive electrode of the secondary battery 100 to the choke coil L13, the supply of power to the output side via the auxiliary coil L14 is blocked by the diode D1. When a voltage is applied to the auxiliary coil L14 from the positive output terminal 200a side, the supply of power to the choke coil L13 is blocked by the diode D1.

  The power conversion device detects an input side voltage VB that is a voltage of the secondary battery 100, and a reactor current IL that is a current that flows through the choke coil L13 (current that flows through the circuit on the input side). A current detection unit 103 and an output side voltage detection unit 202 that detects an output side voltage VH that is a voltage on the output side (the voltage of the capacitor 201) are provided. The detected input side voltage VB, output side voltage VH, and reactor current IL are input to the controller 300.

  The controller 300 performs a calculation based on the input voltage VB, the output voltage VH, and the reactor current IL that are input, and transmits a control signal to the first switching element Q11 and the second switching element Q12. At this time, on the output side, control is performed by selecting one of the first to third modes in accordance with the progress of charging of the capacitor 201.

  The control in the first mode will be described with reference to the time chart of FIG. In the first mode, control A for turning on the first switching element Q11 and turning off the second switching element Q12 and control B for turning off both the first switching element Q11 and the second switching element Q12 are alternately performed. Do. In other words, the second switching element Q12 is always turned off, and the first switching element Q11 is alternately turned on and off.

  In the control A, the amount of change per unit time of the reactor current IL is determined based on the reactor voltage VL that is a voltage applied to the choke coil L13. The reactor voltage VL is obtained by subtracting a value obtained by dividing the output side voltage VH by the turn ratio from the input side voltage VB. Further, the change amount per unit time of the output side current IC that is the current flowing to the second coil L12 side is a value obtained by dividing the change amount dIL / dt per unit time of the reactor current IL by N. An excitation voltage VT, which is a voltage applied to the second coil L12, is equal to the output side voltage VH. The time change amount of the excitation current IM is obtained by dividing the excitation voltage VT by the excitation inductance, and therefore increases linearly and monotonously. Note that the direction in which the excitation current IM flows from the positive output terminal 200a to the negative output terminal 200b is positive.

  A current path when the control A is performed will be described with reference to FIG. In FIG. 3A, current paths are indicated by arrows. The excitation current IM is indicated by a broken line. On the first coil L11 side, the current supplied from the secondary battery 100 takes a path through the choke coil L13, the first coil L11, and the first switching element Q11 in this order. On the second coil L12 side, a path that passes through the sixth switching element Q16, the second coil L12, and the third switching element Q13 in this order is taken. Further, the excitation current IM takes a path that passes through the third switching element Q13, the second coil L12, and the sixth switching element Q16 in this order.

  In the control A, since the reactor current IL monotonously increases, the control B is performed to reduce the reactor current IL on condition that the reactor current IL becomes the first command value Iref1 which is a predetermined value.

  In the control B, the reactor current IL becomes zero. On the other hand, a counter electromotive force is generated in the choke coil L13, and the reactor voltage VL is a negative value obtained by dividing the output side voltage VH by the turn ratio. Therefore, flyback current ID linearly monotonously decreases based on the value of reactor voltage VL, and accordingly reactor current IL also monotonously decreases linearly. Further, the excitation voltage VT becomes a negative value of the output side voltage VH, and the excitation current IM monotonously decreases.

  A current path when the control B is performed will be described with reference to FIG. This current path indicates the path of the period B11 which is the first half of the control B. In the control B, on the first coil L11 side, since the first switching element Q11 and the second switching element Q12 are both OFF, the power supply from the secondary battery 100 is not performed. On the other hand, since the reactor current IL remains in the choke coil L13 and a counter electromotive force is generated, power is supplied through the auxiliary coil L14 by the reactor current IL. Further, the excitation current IM takes a path that passes through the third switching element Q13, the second coil L12, and the sixth switching element Q16 in this order. In addition, since no current flows during the period B12 which is the second half of the control B, the description of the current path is omitted.

  Incidentally, as described above, the flyback current ID in the first mode linearly and monotonously decreases in accordance with the value of the reactor voltage VL during the period in which the control B is performed. Since the reactor voltage VL is based on the output side voltage VH in the control B, the amount of decrease of the flyback current ID per time changes based on the progress of charging on the output side. The flyback current ID in this case will be described with reference to FIG. FIG. 4A is a time chart in a state where the output side voltage VH is close to 0V at the start of charging of the capacitor 201. At this time, the flyback current ID does not sufficiently decrease during the control B period, and the output-side current IC is continuously supplied via the transformer Tr11 during the control A period, and the second transformer Tr12 during the control B period. It will be supplied continuously via.

  FIG. 4B is a time chart when the value of the output side voltage VH is about half of the value obtained by multiplying the input side voltage VB by the turn ratio N. In this case, the increase amount per time of the output side current IC in the control A and the decrease amount per time of the output side current IC in the control B are equal. Therefore, if the first command value Iref1 is set so that the period during which control A is performed and the period during which control B is performed, the flyback current ID can be made zero at the end of control B, and charging The reactor current IL and the flyback current ID can be prevented from excessively increasing.

  FIG. 4C is a time chart when the capacitor 201 is charged and the value of the output side voltage VH approaches VB × N. In this case, in the period B12 that is the latter half of the control B, a period in which the output side current IC is zero is provided.

  Next, the control in the second mode will be described with reference to the time chart of FIG. In the second mode, the control C for turning on both the first switching element Q11 and the second switching element Q12, the control A for turning on the first switching element Q11 and turning off the second switching element Q12, and the first switching element Q11. And the control B which turns off both the 2nd switching element Q12 is performed in order.

  In the control C, the reactor voltage VL applied to the choke coil L13 is equal to the input side voltage VB applied from the secondary battery 100. That is, reactor current IL increases monotonously linearly. At this time, since the first coil L11 is not energized, the output-side current IC is zero.

  A current path when the control C is performed will be described with reference to FIG. Since both the first switching element Q11 and the second switching element Q12 are ON, power is not supplied from the first coil L11 to the second coil L12. In addition, the supply of electric power from the choke coil L13 to the auxiliary coil L14 is also blocked by the diode D1. Therefore, the reactor current IL flowing through the choke coil L13 increases.

  Thus, since the reactor current IL monotonously increases in the control C, the process shifts from the control C to the control A on condition that the reactor current IL becomes the second command value Iref2, which is a predetermined value.

  In the subsequent control A, as shown in FIG. 6B, the same current path as that of the control A in the first mode is taken, so that the description thereof is omitted. Switching from the control A to the control B may be performed under a condition that a predetermined time elapses from the start of the control C, or may be a condition that a predetermined time elapses from the start of the control A. In the time chart of FIG. 4, it is assumed that the reactor current IL monotonously increases in the control A, but the amount of change in the reactor current IL may not increase or decrease depending on the relationship between the input side voltage VB and the output side voltage VH. However, it may decrease monotonously.

  In the control B, since the first switching element Q11 and the second switching element Q12 are both OFF on the first coil L11 side, no current is supplied from the secondary battery 100, and the reactor current IL becomes zero. On the other hand, a counter electromotive force is generated in the choke coil L13, and the reactor voltage VL is a negative value obtained by dividing the output side voltage VH by the turn ratio. Therefore, flyback current ID linearly decreases monotonously, and accordingly reactor current IL also decreases linearly monotonously. Further, the excitation voltage VT becomes a negative value of the output side voltage VH, and the excitation current IM monotonously decreases.

  A current path when the control B is performed will be described with reference to FIGS. 6C and 6D. The current path in FIG. 6C indicates a path in the period B11 that is the first half of the control B. In the control B, on the first coil L11 side, since the first switching element Q11 and the second switching element Q12 are both OFF, the power supply from the secondary battery 100 is not performed. On the other hand, since the reactor current IL remains in the choke coil L13 and a counter electromotive force is generated, power is supplied through the auxiliary coil L14 by the reactor current IL. Further, the excitation current IM takes a path that passes through the third switching element Q13, the second coil L12, and the sixth switching element Q16 in this order. In addition, in the period B11 which is the second half of the control B, since no current flows, description of the current path is omitted. In the period B22, which is a period after the flyback current ID becomes zero, the current path is as shown in FIG. That is, the supply of electric power through the auxiliary coil L14 is finished, and on the output side, an exciting current IM that takes a path passing through the third switching element Q13, the second coil L12, and the sixth switching element Q16 in this order flows. Note that in the period B23, which is the second half of the control B, no current flows as in the first mode, so the description of the current path is omitted.

  Subsequently, the control in the third mode will be described with reference to the time chart of FIG. In the third mode, the control A that turns on both the first switching element Q11 and the second switching element Q12, and the control A that turns on one of the first switching element Q11 and the second switching element Q12 and turns off the other. And alternately. At this time, for control A, the first switching element Q11 is ON and the second switching element Q12 is OFF, and the first switching element Q11 is OFF and the second switching element Q12 is ON. Are performed alternately.

  In the control C, the reactor voltage VL is equal to the input side voltage VB applied from the secondary battery 100, and the reactor current IL increases linearly and monotonously as in the second mode. At this time, since the first coil L11 is not energized, the output-side current IC is zero.

  A current path when the control C is performed will be described with reference to FIG. Since both the first switching element Q11 and the second switching element Q12 are ON, power is not supplied from the first coil L11 to the second coil L12. In addition, the supply of electric power from the choke coil L13 to the auxiliary coil L14 is also blocked by the diode D1. Therefore, the reactor current IL flowing through the choke coil L13 increases. Thus, since the reactor current IL monotonously increases in the control C, the control C shifts to the control A on condition that the reactor current IL becomes the third command value Iref3 that is a predetermined value.

  In the subsequent control A, the reactor current IL decreases linearly and monotonously. That is, the amount of change per unit time of the output side current IC is a value obtained by dividing the amount of change dIL / dt per unit time of the reactor current IL by N. The excitation voltage VT, which is a voltage applied to the second coil L12, is equal to the output side voltage VH, but the polarity is inverted depending on which of the first switching element Q11 and the second switching element Q12 is turned on. . Therefore, it is determined whether the excitation current IM increases or decreases based on the polarity of the excitation voltage VT.

  A current path when the control A is performed will be described with reference to FIGS. 8B and 8C. FIG. 8B shows an example in which the first switching element Q11 is ON and the second switching element Q12 is OFF. On the first coil L11 side, the current supplied from the secondary battery 100 takes a path that passes through the choke coil L13, the first coil L11, and the first switching element Q11. On the second coil L12 side, a path passing through the sixth switching element Q16, the second coil L12, and the third switching element Q13 is taken. FIG. 8C shows an example in which the first switching element Q11 is OFF and the second switching element Q12 is ON. On the first coil L11 side, the current supplied from the secondary battery 100 takes a path that passes through the choke coil L13, the first coil L11, and the second switching element Q12. On the second coil L12 side, a path passing through the fourth switching element Q14, the second coil L12, and the fifth switching element Q15 is taken.

  These first mode, second mode, and third mode are switched according to the value of the output side voltage VH. When charging of the capacitor 201 is started, control is performed in the first mode. When charging proceeds and the output side voltage VH becomes larger than the first predetermined value V1, control is performed in the second mode. When the charging further proceeds and the output side voltage VH becomes larger than the second predetermined value V2, the control is performed in the third mode.

  Electric power can be supplied from the input side to the output side by the control in the first mode when the value obtained by multiplying the input side voltage VB by the turn ratio N is larger than the output side voltage VH. Therefore, assuming that the input side voltage VB is constant, the first predetermined value V1 is set to be smaller than at least a value obtained by multiplying the input side voltage VB, which is a constant, by the turn ratio N. Further, the condition that the reactor current IL decreases in the control A in the third mode is that the value obtained by multiplying the input side voltage VB by the turn ratio N is smaller than the output side voltage VH. Therefore, assuming that the input side voltage VB is constant, the second predetermined value V2 is set to be larger than at least a value obtained by multiplying the input side voltage VB, which is a constant, by the turn ratio N.

  Control A, control B, and control C can also be referred to as first control, second control, and third control, respectively.

  Next, a series of processing executed by the control unit 300 will be described with reference to the flowchart of FIG. The control according to the flowchart of FIG. 9 is executed at a predetermined control cycle.

  First, it is determined whether an activation request has been acquired (S101). The start request command signal is transmitted from, for example, an ECU or the like, which is a host control device. When the activation request has not been acquired (S101: NO), the standby state is continued without performing a series of controls.

  If the activation request is acquired (S101: YES), the output side voltage VH is acquired (S102), and it is determined whether or not the output side voltage VH is equal to or lower than the first predetermined value V1 (S103). If the output side voltage VH is equal to or lower than the first predetermined value V1 (S103: YES), control in the first mode is performed (S104). If the output side voltage VH is not less than or equal to the first predetermined value V1 (S103: NO), it is subsequently determined whether or not the output side voltage VH is less than or equal to the second predetermined value V2 (S105). If the output side voltage VH is less than or equal to the second predetermined value V2 (S105: YES), control is performed in the second mode (S106). On the other hand, if the output side voltage VH is not less than or equal to the second predetermined value V2 (S105: NO), control is performed in the third mode (S107).

  After the control in any one of the first mode, the second mode, and the third mode is performed for a predetermined time, the control end determination is performed (S108). In the process of S108, for example, the output side voltage VH may be acquired again, and it may be determined whether or not the output side voltage VH is equal to or higher than a predetermined upper limit value. The determination as to whether or not the output-side voltage VH has become equal to or higher than a predetermined upper limit value may be made after a negative determination is made in S105. If it is determined that the control is to be terminated (S108: YES), the process is terminated until a start request is made. If it is not determined to end the control (S108: NO), it is determined whether an end request has been acquired (S109). This end request command signal is transmitted from a host control device such as an ECU. If an end request is acquired (S109: YES), a series of processing is ended and the process waits until an activation request is made. If the end request is not acquired (S109: NO), the processing after S102 is executed again.

  In the flowchart of FIG. 9, only control related to charging control for the capacitor 201 is shown, but the power conversion apparatus performs power conversion other than charging control for the capacitor 201. For example, there is a control in which the power supplied via the positive electrode side output terminal 200a and the negative electrode side output terminal 200b is stepped down to charge the secondary battery 100. Since the control is a well-known control, description thereof is omitted.

  With the above configuration, the power conversion device according to the present embodiment has the following effects.

  When the output side voltage VH is small, such as at the start of charging (precharging) of the capacitor 201, the control A that turns on one of the first switching element Q11 and the second switching element Q12 and turns off the other, Control B that turns off both the first switching element Q11 and the second switching element Q12 is alternately performed. Thereby, the current of the choke coil L13 increased in the control A can be decreased in the control B. Therefore, it is possible to prevent the current flowing through the choke coil L13 from continuing to increase. However, in this control B, it is necessary to consume the reactor current IL remaining in the choke coil L13 in the circuit. In this respect, since electric power can be supplied to the output side via the auxiliary coil L14 that is magnetically coupled to the choke coil L13, it is possible to prevent deterioration and damage of the circuit on the input side.

  When the output side voltage VH becomes larger than the first predetermined value V1, the control C shifts to the second mode and turns on both the first switching element Q11 and the second switching element Q12, and the first switching element Q11 The control A for turning on the second switching element Q12 and the control B for turning off both the first switching element Q11 and the second switching element Q12 are sequentially performed. Therefore, the current flowing through the choke coil L13 can be increased by the control C, and the power supply speed to the output side can be improved. Further, the current of the choke coil L13 can be reduced by the control B. Therefore, it is possible to prevent the current flowing through the choke coil L13 from continuing to increase. However, similarly to the first mode, in the control B, it is necessary to consume the reactor current IL remaining in the choke coil L13 in the circuit. In this respect, since electric power can be supplied to the output side via the auxiliary coil L14 that is magnetically coupled to the choke coil L13, it is possible to prevent deterioration and damage of the circuit on the input side.

  Since the auxiliary coil L14 is provided, power can be supplied to the output side via the auxiliary coil L14 in the control B in the first mode and the second mode. This electric power is consumed in the circuit on the input side when the auxiliary coil L14 is not provided. Therefore, the power supply efficiency can be improved by providing the auxiliary coil L14.

  When the output side voltage VH becomes larger than the second predetermined value V2, such as when the precharge to the capacitor 201 further progresses, the mode shifts to the third mode, and the first switching element Q11 and the third switching element Control C for turning on Q13 and turning off the second switching element Q12 and the fourth switching element Q14, and turning off the first switching element Q11, the third switching element Q13 and the fourth switching element Q14, and turning on the second switching element Q12 The control A is turned on alternately. Therefore, the current flowing through the choke coil L13 can be increased by the control C, the current flowing through the choke coil L13 can be decreased by the subsequent control A, and the capacitor 201 that has been charged can be further quickly charged. Can do.

Second Embodiment
In the present embodiment, the control in the third mode is partially different from the first embodiment. FIG. 10 shows the open / closed states of the first switching element Q11 and the second switching element Q12 in the third mode in this embodiment, and the reactor current IL at that time.

  In the third mode, if the increase amount of reactor current IL in control C is equal to the decrease amount of reactor current IL in control A, an excessive increase in reactor current IL can be suppressed. Therefore, the ratio of the period during which the control C is performed to the period during which the control A is performed is set to D: (1-D) using D which is a value less than 1, and using the input side voltage VB and the output side voltage VH. Define D.

  In addition, in the third mode, the timing for switching from the control C to the control A is controlled so that the value obtained by adding the slope current Is to the reactor current IL becomes the correction command value Iref3 * in order to suppress subharmonic oscillation. . The slope current Is will be described with reference to FIG. The slope current Is is a virtual value that increases linearly. If the increase amount of the reactor current IL in the control C is ΔIL and the increase amount of the slope current Is is ΔIs, the third command value Iref3 is set to ΔIL. A correction command value Iref3 *, which is a value obtained by adding ΔIs, is calculated. And control which switches from the control C to the control A is performed so that it may become this correction command value Iref3 *.

  Next, processing executed by the control unit 300 will be described with reference to the control block diagram of FIG. In the constant current control unit 50, the first command value Iref1 that is the command value of the reactor current IL in the first mode, the second command value Iref2 that is the command value of the reactor current IL in the second mode, and the third mode A third command value Iref3, which is a command value of the reactor current IL, is read from the memory and used for control.

  The first command value Iref1 and the second command value Iref2 are output from the constant current control unit 50 as they are. Note that the first command value Iref1 and the second command value Iref2 may be the same value or different values.

  The third command value Iref3 is input to the feedback control unit 51. In addition, the feedback control unit 51 acquires an average value IL_ave that is an actual current of the reactor current IL. The average value IL_ave is obtained by accumulating the reactor current IL detected by the current detection unit 103 for a predetermined period and averaging the values. The third command value Iref3 and the average value IL_ave are input to the adder 52, and the adder 52 takes the difference between the third command value Iref3 and the average value IL_ave. This difference is input to the PI controller 53 and input to the limiter 54. In the limiter 54, if the output value of the PI controller 53 is larger than the upper limit value, the output value is limited to the upper limit value. The output value from the limiter 54 is added to the third command value Iref3 by the adder 55 and output from the feedback control unit 51.

  On the other hand, the input voltage VB and the output voltage VH are input to the current correction unit 57, and the correction amount of the third command value Iref3 is output. Then, a correction command value Iref3 * is obtained by adding to the sum of the third command value Iref3 and the output value of the feedback control unit 51 by the adder 56.

  The first command value Iref1, the second command value Iref2, and the correction command value Iref3 * output from the constant current control unit 50 are input to the mode selection unit 60. Further, the output side voltage VH is also input to the mode selection unit 60, and the output side voltage VH is compared with the first predetermined value V1 and the second predetermined value V2. Then, one of the first command value Iref1, the second command value Iref2, and the correction command value Iref3 * is determined and output.

  One of the first command value Iref1, the second command value Iref2, and the correction command value Iref3 * output from the mode selection unit 60 is input to the peak current control unit 70, converted into an analog value by the DA converter 71, Input to the negative terminal of the comparator 72.

  On the other hand, the slope compensator 73 of the peak current controller 70 generates the value of the slope current Is obtained from the register value as a signal and inputs the signal to the DA converter 74. As described above, the slope current Is is a sawtooth wave signal that monotonously increases linearly from 0 A in each control cycle. Then, the slope current Is and the reactor current IL that have been converted into an analog waveform by the DA converter 74 are added by the adder 75 and input to the plus terminal of the comparator 72. The slope compensator 73 may directly generate an analog waveform and input it to the comparator 72 without going through the DA converter 74.

  The slope compensator 73 sets the value of the slope current Is to zero in the first mode and the second mode, and outputs the aforementioned sawtooth wave slope current Is in the third mode. In the first mode, there is a period in which both the first switching element Q11 and the second switching element Q12 are turned off. During that period, the reactor current IL becomes zero, and as a result, the subharmonic oscillation phenomenon occurs. This is because it does not occur.

  The comparator 72 adds the slope current Is to any one of the first command value Iref1, the second command value Iref2, and the correction command value Iref3 * input to the minus terminal, and the reactor current IL input to the plus terminal. Compare with the value. Then, in a period in which the input value of the plus terminal is smaller than the input value of the minus terminal, a signal in a high state is input to the S terminal of the RS flip-flop 77, and the period in which the input value of the plus terminal is larger than the input value of the minus terminal. , A low signal is input to the S terminal of the RS flip-flop 77. A clock signal from the clock 76 is input to the R terminal of the RS flip-flop 77.

  In the first mode, if the input signal is a low signal, it means that the reactor current IL has exceeded the first command value Iref1. Therefore, the RS flip-flop 77 switches from the control A to the control B by transmitting a signal for turning off both the first switching element Q11 and the second switching element Q12. When one control cycle elapses, the control B is switched to the control A by transmitting a signal for turning on one of the first switching element Q11 and the second switching element Q12 and turning off the other.

  In the second mode, if the input signal is a low signal, it means that the reactor current IL has exceeded the second command value Iref2. Therefore, the RS flip-flop 77 switches from the control C to the control A by transmitting a signal that turns on one of the first switching element Q11 and the second switching element Q12 and turns off the other. Subsequently, when a predetermined time (for example, a half cycle) less than one control cycle has elapsed since the start of the control C, the RS flip-flop 77 generates a signal for turning off both the first switching element Q11 and the second switching element Q12. By switching, control A is switched to control B. When one control cycle elapses, the control B is switched to the control C by transmitting a signal for turning on both the first switching element Q11 and the second switching element Q12.

  In the third mode, if the input signal becomes a low signal, it means that the value obtained by adding the slope current Is to the reactor current IL exceeds the correction command value Iref3 *. Therefore, the RS flip-flop 77 switches from the control C to the control A by transmitting a signal that turns on one of the first switching element Q11 and the second switching element Q12 and turns off the other. And if one control period passes, it will switch from the control A to the control C by transmitting the signal which turns ON both the 1st switching element Q11 and the 2nd switching element Q12.

  The output of the RS flip-flop 77 is input to the duty limiting unit 78. In the duty restriction unit 78, if the length of each control period exceeds the upper limit value, the upper limit value is set. If the length of each control period is less than the lower limit value, the lower limit value is set. Then, a control signal is transmitted to the first switching element Q11 and the second switching element Q12.

  With the configuration described above, the power conversion device according to the present embodiment has the following effects in addition to the effects exhibited by the power conversion device according to the first embodiment.

  The peak current control unit 70 performs constant current control using each command value input from the constant current control unit 50. As a result, when the input side voltage VB changes, the robustness against overcurrent can be improved.

  The slope current is added when the peak current control is performed for the reactor current IL in the third mode. Thereby, subharmonic oscillation of reactor current IL can be suppressed.

<Third Embodiment>
In this embodiment, the circuit configuration of the power converter is different from that of the first embodiment. Moreover, since the circuit configurations are different, some of the processes executed by the control unit 300 are also different.

  FIG. 12 is a circuit diagram of the power conversion apparatus according to the present embodiment. The power conversion circuit 20 included in the power conversion device includes a transformer Tr21 including a first coil L21 and a second coil L22, and first to eighth switching elements Q21 to Q28 that are MOSFETs. The turn ratio of the first coil L21 and the second coil L22 is 1: N.

  The source of the first switching element Q21 and the drain of the second switching element Q22 are connected, and one end of the first coil L21 is connected to the connection point. On the other hand, the source of the third switching element Q23 and the drain of the fourth switching element Q24 are connected, and the other end of the first coil L21 is connected to the connection point. The drain of the first switching element Q21 and the drain of the third switching element Q23 are connected to one end of the choke coil L23, and the other end of the choke coil L23 is connected to the positive electrode of the secondary battery 100. The source of the second switching element Q22 and the source of the fourth switching element Q24 are connected to the negative electrode of the secondary battery 100.

  Since the fifth to eighth switching elements Q25 to Q28 provided on the second coil L22 side are connected in the same manner as the third to sixth switching elements Q13 to Q16 of the first embodiment, description thereof is omitted.

  The choke coil L23 is provided with an auxiliary coil L24 that is magnetically coupled, and the choke coil L23 and the auxiliary coil L24 constitute a second transformer Tr22. Note that the choke coil L23 and the auxiliary coil L24 are wound in the same manner as in the first embodiment, and the diode D2 is also provided in the same manner as in the first embodiment, and thus detailed description thereof is omitted.

  FIG. 13 is a time chart showing processing in the first mode. In the first mode, the control A for turning on the first switching element Q21 and the fourth switching element Q24 and turning off the second switching element Q22 and the third switching element Q23, and the first to fourth switching elements Q21 to Q24 are performed. Control B which turns off both is performed alternately.

  In the control A, similarly to the control A in the first embodiment, the reactor current IL monotonously increases, and accordingly, the output side current IC also monotonously increases. As for the control B, similarly to the control B in the first embodiment, the reactor current IL becomes zero and the flyback current ID monotonously decreases. Accordingly, the output side current IC also monotonously decreases.

  FIG. 14 is a time chart showing processing in the second mode. In the second mode, the control C for turning on the first to fourth switching elements Q21 to Q24, the first switching element Q21 and the fourth switching element Q24 are turned on, and the second switching element Q22 and the third switching element Q23 are turned on. The control A for turning off and the control B for turning off all of the first to fourth switching elements Q21 to Q24 are sequentially performed.

  In the control C, similarly to the control C in the first embodiment, the reactor current IL increases monotonously. On the other hand, since power is not supplied from the first coil L21 to the second coil L22, the output-side current IC is zero. In the control A, similarly to the control A in the first embodiment, the amount of change in the reactor current IL is determined by the relationship between the input side voltage VB and the output side voltage VH. At this time, electric power is supplied from the first coil L21 to the second coil L22, and the output-side current IC conforms to the value of the reactor current IL. In the subsequent control B, similarly to the control B in the first embodiment, the reactor current IL becomes zero, and the flyback current ID monotonously decreases. Accordingly, the output side current IC also monotonously decreases.

  FIG. 15 is a time chart showing processing in the third mode. In the third mode, the control C for turning on the first to fourth switching elements Q21 to Q24, the first switching element Q21 and the fourth switching element Q24 are turned on, and the second switching element Q22 and the third switching element are turned on. Control A for turning off Q23 or control A for turning off the first switching element Q21 and the fourth switching element Q24 and turning on the second switching element Q22 and the third switching element Q23 are alternately performed.

  In the control C, similarly to the control C in the first embodiment, the reactor current IL increases monotonously. On the other hand, since power is not supplied from the first coil L21 to the second coil L22, the output-side current IC is zero. In the control A, similarly to the control A in the first embodiment, the reactor current IL decreases monotonously. At this time, electric power is supplied from the first coil L21 to the second coil L22, and the output-side current IC conforms to the value of the reactor current IL.

  With the above configuration, the power conversion device according to the present embodiment has an effect similar to that of the first embodiment.

<Fourth embodiment>
In this embodiment, the circuit configuration of the power converter is different from that of the first embodiment. Moreover, since the circuit configurations are different, some of the processes executed by the control unit 300 are also different.

  FIG. 16 is a circuit diagram of the power converter according to the present embodiment. The power conversion circuit 30 included in the power conversion device includes a transformer Tr31, first to fourth switching elements Q31 to Q34, first to fourth diodes D31 to D34, and a capacitor C30. A second switching element Q32, which is a MOSFET, is connected in series to the first coil L31 provided as an input side of the transformer Tr31 to form a series connection body, and the first switching element Q31, which is a MOSFET, is connected in parallel to the series connection body. Has been. More specifically, the drain of the first switching element Q31 is connected to one end of the first coil L31, and the drain of the second switching element Q32 is connected to the other end of the first coil L31. The source of the first switching element Q31 and the source of the second switching element Q32 are connected.

  A connection point between the drain of the first switching element Q31 and the first coil L31 is connected to the positive electrode of the secondary battery 100 via the choke coil L33. On the other hand, the connection point between the source of the first switching element Q31 and the source of the second switching element Q32 is connected to the negative electrode of the secondary battery 100.

  A second coil L32 that is magnetically coupled to the first coil L31 is provided on the output side of the transformer Tr31. The turn ratio of the first coil L31 and the second coil L32 is 1: N. On the output side, the third switching element Q33, which is a MOSFET, and the capacitor C30 are connected in series to form a series connection body, and the series connection body and the second coil L32 are connected in parallel to form a parallel connection body. A fourth switching element Q34, which is a MOSFET, is connected in series to the parallel connection body. More specifically, one end of the second coil L32 and one end of the capacitor C30 are connected, the other end of the capacitor C30 and the drain of the third switching element Q33 are connected, and the other end of the second coil L32 and the third switching are connected. The source of the element Q33 is connected. The drain of the fourth switching element Q34 is connected to the connection point between the second coil L32 and the source of the third switching element Q33.

  The connection point between the second coil L32 and the capacitor C30 is connected to the positive output terminal 200a, and the source of the fourth switching element Q34 is connected to the negative output terminal 200b. A capacitor 201 is connected in parallel to the positive output terminal 200a and the negative output terminal 200b.

  An auxiliary coil L34 is magnetically coupled to the choke coil L33, and the choke coil L33 and the auxiliary coil L34 constitute a second transformer Tr32. Note that the choke coil L33 and the auxiliary coil L34 are wound in the same manner as in the first embodiment, and the diode D3 is also provided in the same manner as in the first embodiment, and thus detailed description thereof is omitted.

  FIG. 17 is a time chart showing processing in the first mode. In the first mode, the control A that turns off the first switching element Q31, the third switching element Q33, and the fourth switching element Q34 and turns on the second switching element Q32, and the first switching element Q31 and the second switching element Q32. , And the control B for turning off the fourth switching element Q34 and turning on the third switching element Q33. In other words, the first switching element Q31 and the fourth switching element Q34 are always turned off, and the second switching element Q32 and the third switching element Q33 are alternately turned on.

  In the control A, similarly to the control A in the first embodiment, the reactor current IL monotonously increases, and accordingly, the output side current IC also monotonously increases. As for the control B, similarly to the control B in the first embodiment, the reactor current IL becomes zero and the flyback current ID monotonously decreases. Accordingly, the output side current IC also monotonously decreases.

  FIG. 18 is a time chart showing processing in the second mode. In the second mode, the control C for turning on the first switching element Q31 and the third switching element Q33 and turning off the second switching element Q32 and the fourth switching element Q34, the first switching element Q31, the third switching element Q33, and Control A for turning off the fourth switching element Q34 and turning on the second switching element Q32, turning off the first switching element Q31, the second switching element Q32, and the fourth switching element Q34, and turning on the third switching element Q33 Control B is performed in order.

  In the control C, similarly to the control C in the first embodiment, the reactor current IL increases monotonously. On the other hand, since no power is supplied from the first coil L31 to the second coil L32, the output-side current IC is zero. In the control A, similarly to the control A in the first embodiment, the amount of change in the reactor current IL is determined by the relationship between the input side voltage VB and the output side voltage VH. At this time, electric power is supplied from the first coil L31 to the second coil L32, and the output-side current IC conforms to the value of the reactor current IL. In the subsequent control B, similarly to the control B in the first embodiment, the reactor current IL becomes zero, and the flyback current ID monotonously decreases. Accordingly, the output side current IC also monotonously decreases.

  FIG. 19 is a time chart showing processing in the third mode. In the third mode, the control C for turning on the first switching element Q31 and the third switching element Q33 and turning off the second switching element Q32 and the fourth switching element Q34, and the first switching element Q31 and the third switching element Q33. And the control A which turns off the fourth switching element Q34 and turns on the second switching element Q32 is alternately performed.

  In the control C, similarly to the control C in the first embodiment, the reactor current IL increases monotonously. On the other hand, since no power is supplied from the first coil L31 to the second coil L32, the output-side current IC is zero. In the control A, similarly to the control A in the first embodiment, the reactor current IL decreases monotonously. At this time, electric power is supplied from the first coil L31 to the second coil L32, and the output-side current IC conforms to the value of the reactor current IL.

  With the above configuration, the power conversion device according to the present embodiment has an effect similar to that of the first embodiment.

<Fifth Embodiment>
In the present embodiment, the control in the first to third modes is partially different from that in the first embodiment. Specifically, the reactor current IL is not detected without providing the current detector 103, or the value of the reactor current IL detected by the current detector 103 is not used in the control in the first to third modes. .

  As shown in FIG. 4A of the first embodiment, when the reactor current IL is controlled to be the first command value Iref1 at the end of each control cycle, the reactor current IL is not detected. The current IL may become an excessive value. On the other hand, if control is performed such that the flyback current ID becomes zero at the end of control in each control cycle, the reactor current IL does not reach the first command value Iref1 when switching from the control A to the control B, and the power The supply speed of the is reduced. Therefore, in the control in the first mode in the present embodiment, the control A is performed so that the value obtained by multiplying the flyback current ID at the end of the control in the predetermined control cycle by the turn ratio N becomes the first command value Iref1. Set the length of the displayed period. In addition, after the end of the predetermined control period, a pause period is provided in which the OFF state of the first switching element Q11 and the second switching element Q12 is continued over the predetermined control period in order to make the flyback current ID zero.

  FIG. 20 shows the open / closed states of the first switching element Q11 and the second switching element Q12 in the first mode, the reactor current IL, the value obtained by multiplying the flyback current ID by the turn ratio N, and the output side voltage VH. Is shown. In FIG. 20, from time T1 to time T2, the control A and the control B are alternately repeated to gradually increase the value of the reactor current IL, and from time T2 to time T3 is set as a pause period. Similarly, the reactor current IL is gradually increased in the period from time T3 to time T4 and in the period from time T5 to time T6, and the period from time T4 to time T5 and the period from time T6 to T7 are suspended. The period.

  In the period in which the control A and the control B are alternately repeated, the control A and the control B are alternately repeated for a fixed period (four control periods), and the turn ratio is set to the flyback current ID when the control in the four control periods is completed. The duty value D, which is the ratio of the lengths of the periods during which the control A is performed in each control cycle, is set so that the value obtained by multiplying N becomes the first command value Iref1. That is, the duty value D is set so that the increase amount of the magnetic flux accumulated in the choke coil L13 in the control A is larger than the decrease amount of the magnetic flux in the control B. At this time, ΔI ′, which is an increase amount of the reactor current IL per control cycle, and an increase amount of a value obtained by multiplying the flyback current ID per control cycle by the turn ratio N, is expressed by the following equation (1). The

制御Ａと制御Ｂとを交互に繰り返す制御を固定制御周期繰り返すとすれば、固定制御周期繰り返した後のフライバック電流ＩＤに巻数比Ｎを乗算した値であるΔＩが第１指令値Ｉｒｅｆ１となればよいため、Ｄｕｔｙ値Ｄは次式（２）により求めることができる。すなわち、入力側電圧ＶＢ及び出力側電圧ＶＨを取得することにより、リアクトル電流ＩＬの値を検出することなく。Ｆ制御周期後のフライバック電流ＩＤに巻数比Ｎを乗算した値を第１指令値Ｉｒｅｆ１とすることができる。なお、次式（２）におけるＦの値は、自然数に１制御周期の長さを乗算した値である。

Assuming that the control that alternately repeats the control A and the control B is repeated in the fixed control cycle, ΔI that is a value obtained by multiplying the flyback current ID after repeating the fixed control cycle by the turn ratio N becomes the first command value Iref1. Therefore, the duty value D can be obtained by the following equation (2). That is, by acquiring the input side voltage VB and the output side voltage VH, the value of the reactor current IL is not detected. A value obtained by multiplying the flyback current ID after the F control period by the turn ratio N can be set as the first command value Iref1. Note that the value of F in the following equation (2) is a value obtained by multiplying the natural number by the length of one control cycle.

一方、休止期間におけるフライバック電流ＩＤに巻数比Ｎを乗算した値の時間変化量は、出力側電圧ＶＨを自己インダクタンス及び巻数比Ｎで除算した値として表され、この休止期間においてフライバック電流ＩＤがゼロとなればよい。したがって、休止期間の長さであるＴは、次式（３）で求めることができる。

On the other hand, the amount of time change of the value obtained by multiplying the flyback current ID by the turn ratio N in the idle period is expressed as a value obtained by dividing the output side voltage VH by the self-inductance and the turn ratio N, and in this idle period, the flyback current ID Should be zero. Therefore, T, which is the length of the suspension period, can be obtained by the following equation (3).

このとき、休止期間の長さを制御周期であるＴｓの整数倍の値とする。すなわち、上式（３）で求めた休止期間の長さを制御周期であるＴｓで除算し、小数点以下の値を繰り上げて整数とする。こうすることで、１制御周期の長さを変更することとなく、休止期間の終了時にはフライバック電流ＩＤをゼロとすることができる。

At this time, the length of the suspension period is set to a value that is an integral multiple of Ts that is the control period. That is, the length of the suspension period obtained by the above equation (3) is divided by the control cycle Ts, and the value after the decimal point is carried up to an integer. By doing so, the flyback current ID can be made zero at the end of the pause period without changing the length of one control cycle.

  In order to perform the control in this way, in the first mode, the output side voltage VH gradually increases, the amount of time change of the reactor current IL in the control A becomes small, and the time change amount of the flyback current ID in the control B is absolute. The value gets bigger. Therefore, as in the period from time T7 to time T8 in FIG. 20, even when the duty value D is set to the upper limit value, the flyback current ID may become zero at the end of one control cycle. That is, changes in the reactor current IL and the flyback current ID are equivalent to those shown in FIGS. 4B and 4C of the first embodiment. In this case, the value of the duty value D is obtained by the following equation (4) so that the increase amount of the reactor current IL in one control cycle becomes the first command value Iref1.

なお、Ｄｕｔｙ値Ｄには上限値（例えば４５％）を設けている。そのため、出力側電圧ＶＨの上昇に伴い、Ｄｕｔｙ値Ｄを上限値に設定したとしても、リアクトル電流ＩＬの値は第１指令値Ｉｒｅｆ１に達しなくなる。すなわち、図２０の時刻Ｔ１０以降の状態となる。この場合には、休止期間を設けなくともフライバック電流ＩＤがゼロとなるため、休止期間を設けないものとしてもよい。

The duty value D has an upper limit value (for example, 45%). Therefore, as the output side voltage VH increases, even if the duty value D is set to the upper limit value, the value of the reactor current IL does not reach the first command value Iref1. That is, the state is after time T10 in FIG. In this case, since the flyback current ID becomes zero without providing a pause period, the pause period may not be provided.

  Subsequently, the control in the second mode will be described. In the second mode, in the control C in which both the first switching element Q11 and the second switching element Q12 are turned on, the reactor current IL is controlled to be the second command value Iref2. In the second mode, the total period of the period in which the control C is performed and the period in which the control A is performed is fixed as half of one control cycle. If the ratio of the length of the period during which the control C is performed with respect to one control cycle is the duty value D, the time change amount of the reactor current IL in the control C is a value obtained by dividing the input side voltage VB by L which is a self-inductance. Therefore, the duty value D is expressed by the following equation (5). In determining the duty value D, an upper limit value (for example, 45%) is determined so that the duty value D is smaller than half of one control cycle.

第３モードでは、制御Ｃが行われる期間でのリアクトル電流ＩＬの増加量と、制御Ａが行われる期間でのリアクトル電流ＩＬの減少量とが等しくなるように制御する。このとき、Ｄｕｔｙ値Ｄは次式（６）で求められる。なお、第３モードでは、第１スイッチング素子Ｑ１１と第２スイッチング素子Ｑ１２を共にＯＮとする期間を設けるため、Ｄｕｔｙ値Ｄに上限値（例えば５５％）を設ける。

In the third mode, control is performed so that the increase amount of the reactor current IL in the period in which the control C is performed is equal to the decrease amount of the reactor current IL in the period in which the control A is performed. At this time, the duty value D is obtained by the following equation (6). In the third mode, an upper limit value (for example, 55%) is provided for the Duty value D in order to provide a period during which both the first switching element Q11 and the second switching element Q12 are turned on.

続いて、制御部３００が実行する制御について、図２１の制御ブロック図により説明する。第１モード制御部４００では、出力側電圧ＶＨ及び入力側電圧ＶＢを第１演算部４０１、第２演算部４０２へ入力する。第１演算部４０１では、上式（２）の演算が行われ、Ｄｕｔｙ値Ｄが求められる。一方、第２演算部４０２では、上式（４）の演算が行われ、Ｄｕｔｙ値Ｄが求められる。この算出したＤｕｔｙ値Ｄは選択部４０４に入力され、小さいほうのＤｕｔｙ値Ｄが選択される。このとき、選択部４０４へは、固定周期取得部４０３が取得した固定周期の長さであるＦの値も入力される。この固定周期の長さであるＦの値は予め定められた値であり、例えば４制御周期である。選択されたＤｕｔｙ値ＤはＤｕｔｙ制限部４０５へ入力される。

Next, the control executed by the control unit 300 will be described with reference to the control block diagram of FIG. In the first mode control unit 400, the output side voltage VH and the input side voltage VB are input to the first calculation unit 401 and the second calculation unit 402. In the first calculation unit 401, the calculation of the above equation (2) is performed, and the duty value D is obtained. On the other hand, in the second calculation unit 402, the calculation of the above equation (4) is performed to obtain the duty value D. The calculated duty value D is input to the selection unit 404, and the smaller duty value D is selected. At this time, the value of F that is the length of the fixed period acquired by the fixed period acquisition unit 403 is also input to the selection unit 404. The value of F, which is the length of this fixed cycle, is a predetermined value, for example, 4 control cycles. The selected duty value D is input to the duty restriction unit 405.

  In this way, while calculating the duty value D, the output side voltage VH is input to the idle period calculation unit 406 to calculate the length of the idle period. At this time, as described above, the length of the suspension period is an integral multiple of the control period.

  If the duty value D and the length of the pause period are obtained in this way, these values are input to the calculation unit 407. The calculation unit 407 outputs the value calculated as the duty value D as D1 which is the duty value D indicating the ratio of the length of the ON period of the first switching element Q11 until the fixed period elapses. Further, for D2, which is a Duty value D indicating the length of the ON period of the second switching element Q12, a control signal that is 0%, that is, always OFF is transmitted. On the other hand, if the fixed period has elapsed, a value of 0% is output as both D1 and D2 to control the pause period. This control is performed until the suspension period elapses.

  In the second mode control unit 410, the input side voltage VB is input to the calculation unit 411. In the calculation unit 411, the duty value D is calculated by the above equation (5), and the calculated duty value D is input to the duty restriction unit 412. The duty limiter 412 outputs the duty value D as it is if it is less than or equal to the upper limit value, and sets the duty value D to the upper limit value and outputs it if it is greater than the upper limit value. At this time, the duty value D is output as D2, which is the duty value D indicating the ratio of the length of the ON period of the second switching element Q12. On the other hand, D1, which is a duty value D indicating the ratio of the length of the first switching element Q11, is fixed to 50% and output.

  In the third mode control unit 420, the output side voltage VH and the input side voltage VB are input to the calculation unit 421. The calculation unit 421 calculates the duty value D by the above equation (6), and the duty value D is set to a value equal to or higher than the lower limit value by the duty limiting unit 422. On the other hand, constant voltage control using the command value VH * of the output side voltage VH is also performed. The command value VH * is input to the gradual change unit 423, and is set so that the command value VH * gradually increases with the progress of charging. The command value VH * via the gradual change unit 423 is input to the adder 424, and a difference from the detected output side voltage VH is obtained. This difference is input to the PI controller 425 to calculate the duty value D, and the duty value D is set to a value equal to or higher than the lower limit value by the duty limiting unit 426. The duty value D thus obtained is input to the selection unit 427, and the smaller value is output.

  The intermittent control unit 428 sets the values of D1 and D2 to zero when the output side voltage VH is larger than a predetermined value and when at least one of the input duty value D is smaller than the predetermined value is satisfied. , Stop switching. The predetermined value to be compared with the output side voltage VH is set to a value indicating that charging of the capacitor 201 has been completed. The predetermined value to be compared with the duty value D is set to be larger than at least one of the lower limit value in the duty limiting unit 422 and the lower limit value in the duty limiting unit 426.

  When the duty value D obtained as a result of the constant voltage control is selected by the selection unit 427 and the duty value D is smaller than the predetermined value, the difference between the command value VH * and the output side voltage VH is small. Means. Further, when the duty value D calculated by the calculation unit 421 is selected in the selection unit 427 and the duty value D is smaller than a predetermined value, the value of the output side voltage VH is set to the value of the input side voltage VB. Therefore, when the input duty value D is smaller than the predetermined value, charging of the capacitor 201 proceeds, and the output side voltage VH is equal to the charging of the capacitor 201. It means that the value indicates completion.

  That is, when the charging to the capacitor 201 is completed, further charging is stopped by the determination by the intermittent control unit 428, and then the charging to the capacitor 201 is restarted by the determination by the intermittent control unit 428 when the discharge of the capacitor 201 proceeds. It will be. Therefore, after the charging of the capacitor 201 is completed, the control is performed so that the output side voltage VH repeats gradually decreasing and gradually increasing near the command value VH *.

  The duty value D that has passed through the intermittent control unit 428 in this way is output as D1 that is the duty value D for the first switching element Q11 and D2 that is the duty value D for the second switching element Q12.

  D1 and D2 obtained as described above are input to the mode selection unit 430. The mode selection unit 430 selects which mode is controlled using the output side voltage VH as in the first embodiment, and transmits a control signal to the first switching element Q11 and the second switching element Q12. At this time, the determination may be made using the input side voltage VB as well.

  In this embodiment, the detected output side voltage VH is used. However, when the output side voltage VH is small, more accurate control is possible by taking into account the voltage drop amount VF due to the diode D1. It becomes. In this case, in each equation, the voltage drop amount VF may be added to the output side voltage VH.

  With the above configuration, the power conversion device according to the present embodiment has the following effects.

  In the first mode, when the control that alternately repeats the control A and the control B is performed for a predetermined period, the value obtained by multiplying the flyback current ID by the turn ratio N is controlled to be the first command value Iref1. Yes. Thereby, even when the output side voltage VH is small and the increase amount of the reactor current IL in one control cycle is small, the power supply speed can be improved.

  A pause period is provided in which the control B is continued after the control A and the control B are alternately repeated for a predetermined period. Thereby, the increased reactor current IL can be made zero, and an excessive increase in the reactor current IL can be suppressed.

<Sixth Embodiment>
In the present embodiment, part of the processing executed by the control unit 300 is different from that in the fifth embodiment. Specifically, the value of the reactor current IL detected by the current detection unit 103 is used for the control in the third mode. FIG. 22 is a control block diagram illustrating processing executed by the control unit 300 in the present embodiment. Since the processes in the first mode control unit 400 and the second mode control unit 410 are the same as those in the fifth embodiment, the description thereof is omitted.

  In the third mode control unit 440, the adder 441 calculates the difference between the output side voltage VH and the command value VH *, and the PI controller 442 sets the difference to the constant voltage command value Iref_cv. The constant voltage command value Iref_cv is input to the selection unit 443. On the other hand, a third command value Iref3, which is a command value for constant current control, is also input to the selection unit 443, and the smaller value is output. The constant voltage command value Iref_cv or the third command value Iref3 output from the selection unit 443 is differenced from the reactor current IL by the adder 444 and input to the PI controller 445. A difference between the output of the PI controller 445 and the input side voltage VB is taken by the adder 446, and a multiplier 447 multiplies the value obtained by dividing the turn ratio N by the output side voltage VH, and the calculation result is the adder 448. 1 is subtracted from 1 to obtain a duty value D.

  The calculated duty value D is input to the duty restriction unit 450. The upper limit value D_max obtained by the upper limit value setting unit 449 is also input to the duty limiting unit 450. This upper limit value D_max is determined by the value of the input side voltage VB and the value of the output side voltage VH. If the calculated duty value D is larger than the upper limit value D_max, the duty limit unit 450 outputs the duty value D as the upper limit value D_max.

  D1 and D2 obtained as described above are input to the mode selection unit 430. The mode selection unit 430 selects which mode is controlled using the output side voltage VH as in the first embodiment, and transmits a control signal to the first switching element Q11 and the second switching element Q12.

  By the said structure, the power converter device which concerns on this embodiment has an effect according to the effect which the power converter device which concerns on 5th Embodiment has.

<Seventh embodiment>
In the present embodiment, the control in the first mode is different from the first embodiment. FIG. 23 shows a value obtained by multiplying the open / close state of the first switching element Q11 and the second switching element Q12 in the first mode, the reactor current IL at that time, and the flyback current ID by the turn ratio N.

  In the first mode, if the control A is performed so that the reactor current IL becomes the first command value Iref1, the flyback current ID may not become zero at the end of the period of the control B. In this case, the reactor current IL may increase without limit. In addition, the flyback current ID may become zero before the end of the control B period. In this case, although the situation where the reactor current IL increases indefinitely can be suppressed, the power supply speed decreases.

  On the other hand, if control is performed so that the amount of increase in reactor current IL in control A is equal to the amount of decrease in the value obtained by multiplying the flyback current ID in control B by the turn ratio N, in control A, reactor current IL is There may be a case where the command value Iref1 is not reached. Even in this case, although the situation in which the reactor current IL increases indefinitely can be suppressed, the power supply speed decreases.

  Therefore, in the present embodiment, as shown in FIG. 23, in the control A, the reactor current IL becomes the first command value Iref1, and at the end of the control B, the flyback current ID becomes zero. The length Ts is variable.

  If the reactor current IL is set to the first command value Iref1 in the control A, the following equation (7) is established, and the amount of decrease in the value obtained by multiplying the flyback current ID in the control B by the turn ratio N is the first command value. If the value is Iref1, then the following equation (8) is established.

上式（７）と上式（８）を解くことにより、１制御周期の長さであるＴｓは次式（９）で求まり、Ｄｕｔｙ値Ｄは次式（１０）で求まる。

By solving the above equation (7) and the above equation (8), Ts which is the length of one control cycle is obtained by the following equation (9), and the duty value D is obtained by the following equation (10).

このように制御しているため、コンデンサ２０１への充電が進行し、出力側電圧ＶＨが大きくなるほど１制御周期の長さは短くなる。

Since the control is performed in this way, the charging of the capacitor 201 proceeds and the length of one control cycle becomes shorter as the output side voltage VH increases.

  With the above configuration, the power conversion device according to the present embodiment can improve the power supply speed while suppressing an excessive increase in the reactor current IL.

<Modification>
In the first embodiment, the diode D1 is provided on the negative output terminal 200b side of the auxiliary coil L14. However, as shown in FIG. 24, the diode D1a is provided on the positive output terminal 200a side of the auxiliary coil L14. It may be provided. Even in this case, the same effects as in the first embodiment can be obtained.

  -You may comprise the power converter circuit 10 of 1st Embodiment as shown to Fig.25 (a). Specifically, in the power conversion circuit 10a, the source of the first switching element Q11a and the source of the second switching element Q12a are respectively connected to the ends of the first coil L11a constituting the transformer Tr11a. On the other hand, the drain of the first switching element Q11a and the drain of the second switching element Q12a are connected, and the connection point is connected to one end of the choke coil L13. The center tap of the first coil L11 is connected to the negative electrode of the secondary battery 100. In addition, about the structure by the side of the 2nd coil L12, since it is the same as that of 1st Embodiment, description is abbreviate | omitted. At this time, the processing executed by the control unit 300 is the same as that in the first embodiment. Also in this case, as shown in FIG. 25B, the diode D1a may be provided on the positive output terminal 200a side of the auxiliary coil L14.

  As shown in FIG. 26, also in the full bridge circuit according to the third embodiment, the diode D2a may be provided on the positive output terminal 200a side of the auxiliary coil L24. Although not shown, the diode may be provided on the positive output terminal 200a side of the auxiliary coil L34 in the same manner in the forward active clamp circuit according to the fourth embodiment.

  The second coil L32 side of the power conversion circuit 30 (forward active clamp circuit) according to the fourth embodiment may be configured as shown in FIG. Specifically, one end of the second coil L32 constituting the output side of the transformer Tr31 is connected to the positive output terminal 200a, and the other end is connected to the drain of the fourth switching element Q34a. The connection point between the second coil L32 and the drain of the fourth switching element Q34a is connected to the source of the third switching element Q33a via the capacitor C30a, and the source of the fourth switching element Q34a is connected to the source of the third switching element Q33a. Connected to the drain. The connection point between the fourth switching element Q34a and the third switching element Q33a is connected to the negative output terminal 200b. A third diode D33a is connected in parallel in the reverse direction to the third switching element Q33a, and a fourth diode D34a is connected in parallel in the reverse direction to the fourth switching element Q34. The specific processing executed by the control unit 300 is the same as that in the fourth embodiment, and thus the description thereof is omitted.

  -In each embodiment, although control of 1st-3rd mode shall all be performed, control of at least 2 mode among each mode may be performed. That is, the first mode control may be performed at the start of charging, and the third mode control may be performed without passing through the second mode if the output side voltage VH exceeds a predetermined value. Alternatively, the second mode may be controlled from the start of charging, and the third mode may be performed if the output side voltage VH exceeds a predetermined value.

  In each embodiment, the diodes D1, D1a, D2, D2a, and D3 are used as the rectifying elements connected to the auxiliary coils L14, L24, and L34, but switching is performed instead of the diodes D1, D1a, D2, D2a, and D3. An element may be used. In this case, when power is supplied from the input side to the output side via the auxiliary coils L14, L24, and L34, the switching element may be turned on and energized.

  In the first mode in the first embodiment, the example in which the second switching element Q12 is always turned off has been shown. However, as shown in FIG. 28A, in the control A, the first switching element Q11 is turned on. The case and the case where Q12 is ON may be alternately performed. Further, as shown in FIG. 28B, the control A in which the first switching element Q11 is ON may be performed a plurality of times, and then the control A in which the second switching element Q12 is ON may be performed a plurality of times. .

  In the second mode in the first embodiment, the second switching element Q12 is switched from the control C to the control A by turning off the second switching element Q12. However, as shown in FIG. Control for switching from control C to control A by turning OFF and control for switching from control C to control A by turning off first switching element Q11 may be performed alternately. Further, as shown in FIG. 29 (b), the control to switch from the control C to the control A is performed a plurality of times by turning off the second switching element Q12, and then the first switching element Q11 is turned off. Thus, the control for switching from the control C to the control A may be performed a plurality of times.

  In the first to third modes, control is performed using the first to third command values Iref1 to Iref3. However, in each mode, the length of the period for performing the control A to control C is determined in advance. Control may be performed based on the determined period.

  In each embodiment, the choke coils L13, L23, and L33 are provided on the positive electrode side with respect to the secondary battery 100, but may be provided on the negative electrode side. Further, the choke coils L13, L23, and L33 may be provided on the positive electrode side and the negative electrode side, and auxiliary coils L14, L24, and L34 that are magnetically coupled to each other may be provided.

  The turn ratio between the auxiliary coil L14 and the choke coil may be N or more and 1 :.

  -In embodiment, although the power converter device shall be mounted in a hybrid car, mounting object is not restricted to this.

  -In 5th Embodiment-7th Embodiment, although the control in the power converter device which concerns on 1st Embodiment shall be changed, it can implement similarly also in the power converter device in 3rd, 4th embodiment. That is, each switching element may be controlled using the length setting method of the control A and the control B shown in the fifth to seventh embodiments.

  In the fifth embodiment, the length of the pause period is an integral multiple of the control cycle, and the control A is started after the lapse of the integral multiple of the control cycle. In this regard, the control A may be started when the suspension period calculated by the above equation (3) elapses.

  In the fifth embodiment, the period in which the control A and the control B are alternately performed is a fixed period (four control periods), but the control period may be changed. That is, control is performed such that the value obtained by multiplying the flyback current ID by the turn ratio N at the end of the plurality of control cycles becomes the first command value Iref1, and the flyback current ID becomes zero in the subsequent rest period. That's fine.

  DESCRIPTION OF SYMBOLS 10 ... Power conversion circuit, 20 ... Power conversion circuit, 30 ... Power conversion circuit, 300 ... Control part, C30, C30a ... Capacitor, D1, D1a, D2, D2a, D3 ... Diode, L11, L11a, L21, L31 ... 1 coil, L12, L22, L32 ... 2nd coil, L13, L23, L33 ... choke coil, L14, L24, L34 ... auxiliary coil, Q11-Q16, Q21-Q28, Q31-Q34 ... switching element, Tr11, Tr11a, Tr21, Tr31 ... Transformer.

Claims (20)

A transformer (Tr11, Tr21, Tr31) comprising a first coil (L11, L21, L31) and a second coil (L12, L22, L32) that are magnetically coupled from the input side to which the DC power supply (100) is connected; And power is supplied to the output side circuit through the power conversion circuit (10, 10a, 20, 30, 30a) including the switching elements (Q11, Q11a, Q12, Q12a, Q21 to Q24, Q31 to Q33, Q33a). A power converter that
Choke coils (L13, L23, L33) provided between the power conversion circuit and the DC power source;
In order to make the choke coil function as a flyback transformer, it is connected in parallel to the circuit on the output side, and is magnetically coupled to the choke coil, and an exciting current flows from the positive side of the DC power source to the negative side of the choke coil. The auxiliary coil (L14, L24, L34) wound in the direction in which the exciting current flows from the negative electrode side to the positive electrode side of the circuit on the output side,
A rectifying element (D1) connected in series with the auxiliary coil and blocking power supply from the DC power source to the output side via the auxiliary coil and power supply from the output side to the input side; A power conversion device. The first coil (L11) has a center tap,
The power conversion circuit (10, 10a) includes a first switching element (Q11, Q11a) and a second switching element (Q12, Q12a) connected to both ends of the first coil,
The first switching element and the second switching element are connected to one of a positive electrode and a negative electrode of the DC power supply, and the center tap is connected to the other of the positive electrode and the negative electrode of the DC power supply. Power conversion device. A controller (300) for controlling the first switching element and the second switching element;
The controller is
A first control in which one of the first switching element and the second switching element is turned on and the other is turned off; a second control in which both the first switching element and the second switching element are turned off; A first mode including a period in which
A third control for turning on both the first switching element and the second switching element; and a first control for turning on one of the first switching element and the second switching element and turning off the other. A second mode including a period for sequentially performing the second control for turning off both the first switching element and the second switching element;
The first control in which one of the first switching element and the second switching element is turned on and the other is turned off, and the third control in which both the first switching element and the second switching element are turned on The power conversion device according to claim 2, wherein at least two modes are executed among a third mode including a period in which the steps are sequentially performed. The power conversion circuit (20)
A first switching element (Q21) and a second switching element (Q22) connected in series; a third switching element (Q23) and a fourth switching element (Q24) connected in series;
One end of the first coil is connected to a connection portion between the first switching element and the second switching element, and the other end of the first coil is connected to a connection portion between the third switching element and the fourth switching element. ,
A full bridge circuit in which the first switching element and the third switching element are connected to a positive electrode side of the DC power supply, and the second switching element and the fourth switching element are connected to a negative electrode side of the DC power supply; The power conversion device according to claim 1. A control unit (300) for controlling the first to fourth switching elements;
The controller is
The first switching element and the fourth switching element are turned on, the second switching element and the third switching element are turned off, or the second switching element and the third switching element are turned on. A first mode including a period for sequentially performing a first control for turning off the first switching element and the fourth switching element and a second control for turning off all of the first to fourth switching elements. When,
Third control for turning on all of the first to fourth switching elements; turning on the first switching element and the fourth switching element; turning off the second switching element and the third switching element; Or the first control for turning on the second switching element and the third switching element and turning off the first switching element and the fourth switching element, and the first to fourth switching elements. A second mode including a period of sequentially performing the second control in which both are turned off,
The third control for turning on the first to fourth switching elements, the first switching element and the fourth switching element are turned on, and the second switching element and the third switching element are turned off. Or a period of time in which the first control for turning on the second switching element and the third switching element and turning off the first switching element and the fourth switching element are sequentially performed. The power converter according to claim 4 which performs at least two modes among three modes. The power conversion circuit (30, 30a)
A first switching element (Q32) connected in series to the first coil;
A second switching element (Q31) connected in parallel to the first coil and the first switching element;
2. The active clamp circuit according to claim 1, further comprising: an active clamp circuit having a third switching element (Q33, Q33a) and a capacitor (C30, C30a) connected in parallel or in series with the second coil. Power conversion device. A control unit (300) for controlling the first to third switching elements;
The controller is
A first control for turning off the first switching element and the third switching element and turning on the second switching element; turning off the first switching element and the second switching element; and turning off the third switching element. A first mode for performing the second control to be ON;
A third control for turning on the first switching element and the third switching element and turning off the second switching element; turning off the first switching element and the third switching element; and turning on the second switching element. A second mode for performing the first control to be turned on, and the second control to turn off the first switching element and the second switching element and turn on the third switching element;
The third control for turning on the first switching element and the third switching element and turning off the second switching element; turning off the first switching element and the third switching element; and The power conversion device according to claim 6, wherein at least two modes are executed among the first mode in which the first control is turned on and the third mode in which the first control is performed. A voltage detector that detects the output voltage as an output voltage;
If the output voltage is less than a first predetermined value, execute the first mode;
When the output voltage is larger than the first predetermined value and smaller than a second predetermined value larger than the first predetermined value, the second mode is executed,
The power converter according to claim 3, 5 or 7, wherein the third mode is executed when the output voltage is larger than the second predetermined value. A voltage detector that detects the output voltage as an output voltage;
When the output voltage is smaller than a predetermined value, the first mode is executed,
The power converter according to claim 3, 5 or 7, wherein the third mode is executed when the output voltage is larger than the predetermined value. A voltage detector that detects the output voltage as an output voltage;
When the output voltage is smaller than a predetermined value, the second mode is executed,
The power converter according to claim 3, 5 or 7, wherein the third mode is executed when the output voltage is larger than the predetermined value. A current detector (103) for detecting a current value of the choke coil;
The power conversion according to any one of claims 3, 5, and 7 to 10, wherein the control unit controls each switching element so that the current value becomes a predetermined value in each mode. apparatus. The control unit further includes a slope compensation unit that adds a slope signal that is a sawtooth wave to the current value,
The power converter according to claim 11, wherein the slope compensator does not add the slope signal in the first mode and the second mode, and adds the slope signal in the third mode.   In the first mode, the control for increasing the amount of increase in the magnetic flux stored in the choke coil in the first control to be larger than the amount of decrease in the magnetic flux in the second control is continued for a predetermined control period, and The power converter according to any one of claims 3, 5, and 7, wherein a pause period in which the second control is continued is provided.   The power converter according to claim 13, wherein the predetermined control cycle is a predetermined control cycle. A voltage detector that detects the output voltage as an output voltage;
The power converter according to claim 13 or 14, wherein the pause period is shortened as the output voltage increases. A voltage detector that detects the output voltage as an output voltage;
The power converter according to claim 13 or 14, wherein a ratio of performing the first control in one control cycle is increased as the output voltage increases.   The length of the said idle period is a power converter device of any one of Claims 13-16 set so that the electric current which flows through the said choke coil may become zero.   An upper limit is set for the ratio for performing the first control in one control cycle, and the current flowing through the choke coil becomes zero by the second control when the ratio for performing the first control is set as the upper limit. The power converter according to any one of claims 13 to 17, wherein the pause period is not provided. A current detection unit for detecting a current value of the choke coil;
The power converter according to any one of claims 13 to 18, wherein, in the third mode, control is performed so that the detected current value becomes a command value.   In the first mode, the current flowing through the choke coil is controlled to be a predetermined value in the first control, and the current flowing through the choke coil at the time of switching from the second control to the first control is The power converter according to any one of claims 3, 5, and 7, wherein a length of one control cycle is set so as to be zero.

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