JP2014230432A - Dc power source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power source device that supplies a voltage so as to prevent occurrence of a ripple current even for a load that has a high voltage.SOLUTION: A DC power source device comprises: a current control section 1 connected to a load 5, which has a DC voltage Vc, and configured to control a current, flowing in the load 5, by use of a plurality of switching elements 11 to 14; a DC power source section 2 configured to generate a voltage V1 smaller than the voltage Vc of each end of the load 5, and to input the voltage V1 to the current control section 1; and a boosting power source section 3 configured to output a DC voltage VB equal to the voltage Vc of each end of the load 5. The load 5 and the boost power source section 3 are connected in series in reverse polarity. Further, the DC power source section 2 is connected, via the current control section 1, to a point between the load 5 and boost power source section 3. The voltage V1 is superposed on a DC voltage VB with predetermined on-duty by the operation of each of the switching elements 11 to 14 of the current control section 1, and it is supplied to the load 5.

Description

  The present invention relates to a DC power supply apparatus that supplies a DC high voltage to a load.

A battery that outputs a high voltage is widely used, for example, in an automobile having a traveling motor, a power storage system combined with solar power generation, and the like. For example, a regenerative type power supply device is connected to such a high voltage type battery so as to suppress the consumption of electric power stored in the battery.
FIG. 1 is an explanatory diagram showing a configuration of a conventional DC power supply device. This figure shows a buck converter portion having a choke coil 103 in a DC power supply device.
The device shown in FIG. 1 is a half bridge that connects two switches 101 (Q1) and 102 (Q2) in series and supplies current to a load 105 via a choke coil 103 connected to the connection point of these switches. A circuit is formed.
A smoothing capacitor 104 is connected in parallel to the load 105 on the connection line between the choke coil 103 and the load 105.
The load 105 has a high potential side electrode connected to one end of the choke coil 103 and a low potential side electrode connected to the ground.

FIG. 2 is an explanatory diagram showing the operation of the DC power supply device of FIG. The upper part of the figure is a graph showing the change over time of the current flowing through the load 105, the vertical axis represents the current flowing through the load 105, and the horizontal axis represents the operating time (elapsed time) of the DC power supply device.
As shown in FIG. 1, a voltage + V on the high potential side higher than the ground level is applied to one end of the switch 101 (Q1), and a low potential side lower than the ground level is applied to one end of the switch 102 (Q2). The voltage −V is applied.
The load 105 is a rechargeable battery pack, for example, and is configured to output a high voltage. When the voltage across the load 105 is Vc, the absolute values of the voltage V and the voltage −V applied to the switch 101 are larger than the voltage Vc.
As shown in the lower part of FIG. 2, this DC power supply device is switched on so that the switch 101 (Q1) and the switch 102 (Q2) are alternately turned on and not turned on at the same time and turned off at the same time. It is controlled.
In the operation shown in FIG. 2, the switch 101 (Q1) and the switch 102 (Q2) are alternately turned on and off in the same cycle, and the increase or decrease of the current flowing through the load 105 at this time is shown in the upper part of FIG. ing.

Here, when the inductance of the choke coil 103 is L, the rate of change of the current flowing through the load 105 when the switch 101 is in the on state and the switch 102 is in the off state is expressed as dI / dt = (V−Vc) / L. As the time elapses, the current I flowing to the load 105 increases.
When the switch 101 is in the off state and the switch 102 is in the on state, the current change rate is dI / dt = (− V−Vc) / L, and the current I decreases with time.
As described above, when the voltage V and the voltage −V are alternately switched and supplied to the load 105, a triangular wave current (ripple current Ir) as shown in the upper part of FIG.
In the circuit shown in FIG. 1, the smoothing capacitor 104 is connected to the connection point between the choke coil 103 and the load 105. However, when the load 105 is an in-vehicle battery pack or the like, the AC impedance may be very small. Many. Therefore, the smoothing capacitor 104 connected in parallel with the load 105 cannot sufficiently absorb the triangular wave current (ripple current Ir).

  In order to suppress the ripple current Ir, it is conceivable to configure the circuit by increasing the inductance L of the choke coil 103, or to provide a separate ripple filter circuit or the like. As a result, the cost increases, and the circuit or device becomes large.

Some conventional power supply devices include a buck converter configured by connecting four switch elements in series to control the output voltage (see, for example, Patent Document 1).
FIG. 3 is an explanatory diagram showing another configuration of a conventional DC power supply device. This figure shows a buck converter portion of a DC power supply device, and is configured by connecting four switch elements in series in substantially the same manner as that described in Patent Document 1 described above. 3 is different from the circuit described in Patent Document 1 in the on / off operation of each switch element.
In the circuit of FIG. 3, four switches 110 to 113 are connected in series, a voltage V having a potential higher than the ground level is supplied to one end of the switch 110 (Q1), and a ground level is connected to one end of the switch 113 (Q2). A voltage −V having a lower potential is supplied.

One end of a choke coil 124 (L) is connected to a connection point between the switch 111 (q1) and the switch 112 (q2), which is the center of the switches 110 to 113 connected in series. In this device, the switches 110 to 113 and the load 105 are connected by the choke coil 124 (L). When the load 105 is a battery, for example, the load is connected to the other end of the choke coil 124 (L). The high potential side electrode 105 is connected.
The cathode of the diode 114 is connected to the connection point between the switch 110 (Q1) and the switch 111 (q1), and the anode of the diode 115 is connected to the connection point between the switch 112 (q2) and the switch 113 (Q2). Has been. The cathode of the diode 115 is connected to the anode of the diode 114, and this connection point is grounded.

The switches 110 (Q1) to 113 (Q2) are controlled to be turned on / off by a control unit (not shown).
FIG. 4 is an explanatory diagram showing the operation of the DC power supply device of FIG. The upper part of the figure is a graph showing the change with time of the current flowing through the load 105 in FIG. 3, the vertical axis shows the current and the horizontal axis shows the elapsed time.
In addition, the operation illustrated in FIG. 4 is performed by the switch operation of the switch 110 (Q1) and the switch 112 (q2) when the switch 111 (q1) is kept on and the switch 113 (Q2) is kept off. It shows the flowing current, and the illustration of the current change when each switch is in another state is omitted. In other words, the switch operation when the voltage V is supplied to the load 105 is shown, and the switch operation when the voltage −V is supplied to the load 105 is omitted.
In the drawing, a current change indicated by a solid line indicates a current that flows when the voltage V is supplied to the load 105 and the load 105 is grounded as described later. In addition, the current change indicated by the one-dot broken line in the figure is a triangular wave current generated when the voltage V and the voltage −V are alternately supplied to the load 105 as described with reference to FIGS. 1 and 2, for example. is there.

Here, the inductance of the choke coil 124 in FIG. 3 is L, and the voltage across the load 105 is Vc.
In the switch operation shown in FIG. 4, when the switch 110 (Q1) is turned on and the switch 112 (q2) is turned off, the voltage V is supplied to the load 105. At this time, the rate of change of the current I flowing through the load 105 Is dI / dt = (V−Vc) / L.
Further, the switch 110 (Q1) is turned off and the switch 112 (q2) is turned on, so that the voltage V is not supplied to the load 105, and the high potential side electrode of the load 105 is connected via the choke coil 124 and the diode 115. The rate of change of the current I that flows when grounded is dI / dt = −Vc / L.

Here, the current change rate dI / dt is the slope of the characteristic curve (triangular wave current) representing the current change shown in the upper part of FIG. If this slope, that is, dI / dt is “0”, it means that there is no triangular wave current (ripple current).
When the load 105 is connected to the ground after the voltage V is supplied to the load 105, dI / dt when the current drops decreases, and the current gently flows out from the high potential side electrode of the load 105.

Japanese Patent No. 4944208

  Since the conventional DC power supply device is configured as described above, the higher the voltage at both ends of the load, the larger the ripple current is generated when the current flows from the DC power supply device to the load. In addition, when the ripple current is suppressed using a choke coil, there is a limit to the size of the inductance because the transient characteristics of the circuit are deteriorated. For example, when handling a battery pack that generates a high voltage as a load It becomes difficult to effectively suppress the generation of ripple current. Therefore, there is a problem that it is difficult to measure the current flowing through the load and to measure the charge / discharge characteristics and the like with desired accuracy.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a DC power supply device that supplies a voltage to a load having a high voltage so as to suppress generation of a ripple current.

  A DC power supply device according to the present invention is connected to a load having a DC voltage, and uses a plurality of switch elements to control a current flowing through the load, and a first DC voltage smaller than a voltage across the load. And a second power source that generates a second DC voltage equal to the voltage across the load, and the load and the second power source. The first power source unit is connected in series via the current control unit between the load and the second power source, and the first power source unit is connected in series via the current control unit. One DC voltage is superimposed on the second DC voltage with a predetermined on-duty and supplied to the load.

The current control unit connects one end of the first switch element and one end of the second switch element in series, connects one end of the third switch element and one end of the fourth switch element in series, and is connected in series. A full bridge circuit formed by connecting in parallel the first and second switch elements and the third and fourth switch elements connected in series;
(1) A connection point connecting the other end of the first switch element and the other end of the third switch element is a first connection point,
(2) A connection point connecting the other end of the second switch element and the other end of the fourth switch element is a second connection point,
(3) A connection point connecting one end of the first switch element and one end of the second switch element is a third connection point,
(4) A connection point connecting one end of the third switch element and one end of the fourth switch element is a fourth connection point,
(5) When the first connection point and the second connection point are input points of the full bridge circuit, and the third connection point and the fourth connection point are output points of the full bridge circuit,
A capacitor that connects the output points; a choke coil that connects the output point and the capacitor; and a switch control unit that controls on / off operations of the fourth switch element from the first switch element; The output terminal of the first power supply unit is connected so that the first DC voltage is supplied between the input points, and the high potential side voltage of the load is applied to the third connection point. The second power supply unit is connected to the other end of the capacitor such that a high potential side electrode of the load is connected to one end of the capacitor, and a high potential side voltage of the second DC voltage is supplied to the fourth connection point. A low potential side output terminal of the second DC power supply unit is connected to the low potential side electrode of the load, and the switch control unit includes the first switch element and the first switch element. 3 switch elements In this case, Tm is the time width of the narrower time width for turning on, and the on / off state of the switch device having the wider time width of the on state and the on time of the switch device having the smaller time width of the on state. When the overlap period in which the OFF state is the same is Td, and the drive overlap ratio indicating the ratio of the overlap period Td to the time width Tm is Rd = (Td / Tm) × 100%, the drive overlap ratio Rd is The operation of each switch element is controlled so as to be 50% or more and 100% or less, and the first switch element and the second switch element are alternately turned on / off, and the third switch element and the fourth switch element are Are alternately turned on and off to output a supply current to be supplied from the full bridge circuit to the load, and during the period in which the supply current is not output, the first switch element and the third switch The switch elements are both turned on to connect the third connection point and the fourth connection point to flow an inertial current.

  The current control unit is connected to the first switch element, the second switch element, the third switch element, and the fourth switch element that are connected in series, and at a connection point between the second switch element and the third switch element. The other end of the choke coil is connected to the other end of the choke coil, the other end of the choke coil is connected to the ground, and the other end of the choke is grounded. A switch control unit for controlling on / off operation of the switch element; a first diode for connecting a cathode to a connection point between the first switch element and the second switch element; the third switch element; and the fourth switch element. A second diode for connecting an anode to a connection point with the switch element, and the first power supply unit generates a first DC voltage having a positive voltage polarity and a first DC voltage having a negative voltage polarity. The positive first DC voltage output terminal is connected to one end of the first switch element, the negative first DC voltage output terminal is connected to one end of the fourth switch element, and the positive first DC voltage output terminal is connected to one end of the fourth switch element. An output terminal serving as a center potential of one DC voltage and the negative first DC voltage is connected to the anode of the first diode and the cathode of the second diode, and is grounded. A high-voltage side output terminal of a DC voltage is connected to an output terminal serving as a central potential of the first power supply unit, and a low-voltage side output terminal of the second DC voltage is connected to a low-potential side electrode of the load; The switch control unit controls the first and second switches to be in an ON state, supplies the positive first DC voltage to the choke coil, and sharply increases the current flowing through the load, and then the first Switch the switch to the off state Forming a current circuit including the second switch, the choke coil, the second power supply unit, and the first diode in an on state, and causing an inertial current due to energy accumulated in the choke coil to flow to the load Control, and the third and fourth switches are controlled to be in an on state, the negative first DC voltage is supplied to the choke coil, the current flowing through the load is sharply reduced, and then the fourth switch is turned off. The inertial current due to the energy accumulated in the choke coil is formed by forming a current circuit including the third switch, the choke coil, the second power supply unit, and the second diode in the on state by transitioning to the state. And performing a second control to flow through the first.

  Further, the second power supply unit detects a voltage across the load and generates a second DC voltage equal to the detected voltage.

  According to the present invention, the ripple component of the current flowing through the load having a high voltage can be reduced, and the current flowing through the load can be controlled or measured with high accuracy.

It is explanatory drawing which shows the structure of the conventional DC power supply device. It is explanatory drawing which shows operation | movement of the DC power supply device of FIG. It is explanatory drawing which shows the other structure of the conventional DC power supply device. It is explanatory drawing which shows operation | movement of the DC power supply device of FIG. It is explanatory drawing which shows schematic structure of the DC power supply device by Example 1 of this invention. It is explanatory drawing which shows operation | movement of the DC power supply device of FIG. It is explanatory drawing which shows operation | movement of the DC power supply device of FIG. It is explanatory drawing which shows operation | movement of the full bridge circuit of a current control part. It is explanatory drawing which shows operation | movement of the DC power supply device of FIG. It is explanatory drawing which shows schematic structure of the DC power supply device by Example 2 of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Example 1
FIG. 5 is an explanatory diagram showing a schematic configuration of the DC power supply device according to Embodiment 1 of the present invention. The illustrated DC power supply includes a switch 11 (Q1) to a switch 14 (q2), choke coils 16 and 17 that remove high-frequency components included in circuit current, an output capacitor 18 that smoothes circuit voltage and the like, and switch 11 ( The current control unit 1 includes a switch control unit 4 that controls each switch operation of the switches Q1) to 14 (q2). Further, a DC power supply unit 2 that supplies a DC voltage V1 to the current control unit 1 and a boost power supply unit 3 that supplies a boost voltage VB to the current control unit 1 are provided.
The DC power supply device shown in FIG. 5 is connected to a load 5 made of, for example, a battery pack that generates a DC voltage Vc.

The current control unit 1 connects the switch 11 (Q1) and the switch 12 (Q2) in series, connects the switch 13 (q1) and the switch 14 (q2), and connects these series-connected switch trains in parallel. A full-bridge circuit configured as described above.
The connection point (input point of the full bridge circuit) between the switch 11 (Q1) and the switch 13 (q1) is connected to the high potential side output terminal of the DC power supply unit 2. The connection point (input point of the full bridge circuit) between the switch 12 (Q2) and the switch 14 (q2) is connected to the low potential side output terminal of the DC power supply unit 2.
One end of the choke coil 16 is connected to a connection point between the switch 11 (Q1) and the switch 12 (Q2) (first output point of the full bridge circuit). One end of the choke coil 17 is connected to a connection point between the switch 13 (q1) and the switch 14 (q2) (second output point of the full bridge circuit).

The other end of the choke coil 16 is connected to the high potential side of the load 5, that is, the plus electrode, and the other end of the choke coil 17 is connected to the high potential side output terminal of the boost power supply unit 3. An output capacitor 18 is connected between the other end of the choke coil 16 and the other end of the choke coil 17, that is, between the output points of the full bridge circuit.
The low potential side of the load 5, that is, the negative electrode is connected to the low potential side output terminal of the boost power supply unit 3. Further, both electrodes of the load 5 are connected to a voltage detection terminal of the boost power supply unit 3 and the like. That is, the load 5 and the boost power supply unit 3 are connected in series in reverse polarity, and the DC power supply unit 2 is connected in series between the boost power supply unit 3 and the load 5 via the current control unit 1.
The switches 11 (Q1) to 14 (q2) are made of, for example, MOSFET semiconductor switch elements, and gates serving as control terminals are connected to the switch control unit 4, respectively.

The switch control unit 4 includes a processor, a memory, and the like. For example, the switch 11 (Q1) to the switch 14 according to a setting command input from the outside or according to a control program stored in its own internal memory. (Q2) is configured to be turned on / off.
The DC power supply unit 2 includes a power supply circuit that generates the DC voltage V1 as described above, and has a current capacity that does not change the output voltage V1 when the load 5 is connected to the current control unit 1.

The output voltage V1 of the DC power supply unit 2 is used as follows.
1) Supplying energy to make up for loss due to heat generation or the like of wiring parts connecting the switch elements or the load 5 constituting the current control unit 1 and to continue the current flowing between the current control unit 1 and the load 5 .
2) In general, the boost power supply unit 3 is slow in adjusting the voltage VB with respect to the high speed of the transient response / rise characteristics of the current control unit 1 and the like. For example, when the load 5 is a capacitive battery or the like, the voltage drop due to the internal impedance of the load 5 changes when the load current increases. Therefore, when the voltage Vc changes, the follow-up of the voltage VB output from the boost power supply unit 3 to the current control unit 1 is not in time. When the voltage VB is adjusted in response to such a change in the voltage Vc, the energy of the voltage V1 output from the DC power supply unit 2 is transiently replenished.
The voltage V1 is set to a voltage value including an appropriate margin in order to correspond to the internal impedance of the battery, the characteristics of the current circuit (such as the current control unit 1), the response speed of the boost power supply unit 3, and the like. However, it is generally smaller than the voltage VB and the voltage Vc.

When the load 5 is, for example, a battery pack that generates a DC voltage Vc of 300 [V], the boost power supply unit 3 is configured to generate and output at least a DC voltage VB of 300 [V]. . Note that the voltage VB output from the boost power supply unit 3 is the same as the voltage Vc across the load 5 and when the polarity is aligned so as to be connected in series with the voltage V1, that is, when superimposed so as to be V1 + VB. This is the voltage value at which the discharge current flows from the load 5 when it is superimposed on the voltage V1 having the charge voltage of the load 5 and superimposed on the voltage V1 whose polarity is inverted, that is, when it is superimposed so as to be −V1 + VB.
Further, the boost power supply unit 3 is configured to detect the voltage Vc across the load 5, and when the detected voltage is Vs, the magnitude of the voltage VB is adjusted to be equal to the voltage Vs. Configured to generate.

Next, the operation will be described.
The boost power supply unit 3 detects the voltage Vc across the load 5, generates a voltage VB equivalent to the detected voltage Vs, and outputs the high potential side voltage of the voltage VB to the current control unit 1. The voltage is applied to the connection point between 17 and the output capacitor 18. Further, the low potential side voltage of the voltage VB is applied to the low potential side electrode of the load 5. In other words, the boost power supply unit 3, the current control unit 1 and the load 5 form a series circuit, and the voltage VB from the boost power supply unit 3 is opposite to the voltage Vc across the load 5 (battery). Therefore, these combined voltages are constantly 0 [V].
Therefore, the current control unit 1 can control the current flowing through the series circuit with a small voltage that can overcome the circuit impedance.
The DC power supply unit 2 supplies, for example, the high potential side voltage of the voltage V1 to the connection point between the switch 11 (Q1) and the switch 13 (q1), and the low potential side voltage of the voltage V1 is the switch 12 (Q2) and the switch 14. Supply to the connection point with (q2). That is, the voltage V1 is supplied between the input points of the aforementioned full bridge circuit.

When the switch 11 (Q1) and the switch 14 (q2) are controlled to be in an on state and the switch 12 (Q2) and the switch 13 (q1) are in an off state by the switch control unit 4, the voltage V1 + VB is choked. Applied to both ends of a series circuit portion formed by the coils 16 and 17 and the load 5. Here, the on / off state of the switch 11 (Q1) to the switch 14 (q2) is a first switch state.
When the switch 11 (Q1) and the switch 14 (q2) are controlled to be in the off state and the switch 12 (Q2) and the switch 13 (q1) are controlled to be in the on state, the voltage of −V1 + VB is the choke coil 16, Applied to both ends of the series circuit portion of 17 and the load 5. Here, the on / off state of the switch 11 (Q1) to the switch 14 (q2) is a second switch state.

FIG. 6 is an explanatory diagram showing the operation of the DC power supply device of FIG. This figure shows an operation example of the current control unit 1 under the control of the switch control unit 4, and is a timing chart showing the operation timing of the switch 11 (Q1) to the switch 14 (q2). In the figure, a period showing a high level is an on state, and a period showing a low level is an off state.
In the switch operation shown in FIGS. 6A and 6B, in addition to the first switch state and the second switch state described above, a period in which both the switch 11 (Q1) and the switch 13 (q1) are in the on state. In addition, there is a period during which both the switch 12 (Q2) and the switch 14 (q2) are turned on.
Note that there is no period during which both the switch 11 (Q1) and the switch 12 (Q2) are in the on state and a period during which both the switch 13 (q1) and the switch 14 (q2) are in the on state.
Each of the switch operations described above is performed according to the purpose of supplying power to the load 5 and the like. When only the switch operation shown in FIG. 6A is performed, only the switch operation shown in FIG. In some cases, the switch operations shown in FIGS. 6A and 6B are performed in combination.

In the operation illustrated in FIG. 6A, the switch control unit 4 synchronizes, for example, the timing at which the switch 11 (Q1) transitions to the off state and the timing at which the switch 12 (Q2) transitions to the on state. The on / off states of (Q1) and switch 12 (Q2) are reversed to alternately turn on / off (the above switch operations have dead time, but are shown here for the sake of simplicity). Etc.).
Further, for example, the timing at which the switch 13 (q1) transitions to the OFF state and the timing at which the switch 14 (q2) transitions to the ON state are synchronized, and the switches 13 (q1) and 14 (q2) are inverted to alternately On / off.
Further, the timing at which the switch 11 (Q1) transitions to the off state and the timing at which the switch 13 (q1) transitions to the off state are not synchronized. Furthermore, the timing at which the switch 12 (Q2) transitions to the on state and the timing at which the switch 14 (q2) transitions to the on state are not synchronized.

When the switch control unit 4 controls the switch operation as described above, the on-duty of the switch 11 (Q1) is made larger than the on-duty of the switch 13 (q1). In other words, the switch operation is performed so that the on-duty of the voltage V1 output from the current control unit 1 is 50 [%] or less.
By controlling each switch operation in this manner, both the switch 11 (Q1) and the switch 14 (q2) are turned on during the “transmission period” shown in FIG. 6A, and the switch 12 (Q2 ) And the switch 13 (q1) are both turned off. In this transmission period, when the total inductance of the choke coils 16 and 17 is L and the voltage applied to the inductance L is VL, VL = V1 + VB−Vc, and when VB = Vc, VL = V1. Become.
Since the current increase rate at this time is expressed as dI / dt = V1 / L, the increase rate of the load current, that is, the slope when the triangular wave current increases is determined by the value of the voltage V1, and the application time of the voltage VL is determined. The amount of current increase can be adjusted.
In this way, the circuit current can be controlled by changing the length of the transmission period.
In addition, the switch control unit 4 controls each switch operation so that the length of the transmission period, that is, the on-duty of the voltage V1 is basically around 50 [%], and is effective in suppressing the ripple current. As described above, the above-described control is performed by setting the above-described on-duty.

In the switch operation shown in FIG. 6B, the on / off states of the switch 11 (Q1) and the switch 12 (Q2) connected in series are reversed as in the operation shown in FIG. The switch timing is synchronized so as to alternately turn on and off.
Further, the switch timings are synchronized so that the on / off states of the switch 13 (q1) and the switch 14 (q2) connected in series are reversed and alternately turned on / off.
In addition, the timing at which the switch 11 (Q1) and the switch 13 (q1) transition from the off state to the on state is synchronized, and the timing at which the switch 12 (Q2) and the switch 14 (q2) transition from the on state to the off state is synchronized. Synchronized.
In this switch operation, the timing at which the switch 11 (Q1) transitions to the off state and the timing at which the switch 13 (q1) transitions to the off state are not synchronized. Furthermore, the timing at which the switch 12 (Q2) transitions to the on state and the timing at which the switch 14 (q2) transitions to the on state are not synchronized.

6A and 6B, the “transmission period” in which the supply current is output exists between the first “pause period” and the second “pause period”.
In each pause period shown in FIGS. 6A and 6B, a period in which both the switch 11 (Q1) and the switch 13 (q1) are on, and a switch 12 (Q2) and a switch 14 (q2). ) Are both in the on state.

During the period when both the switch 11 (Q1) and the switch 13 (q1) are on, or during the period when both the switch 12 (Q2) and the switch 14 (q2) are on, the DC power supply unit The voltage V1 generated by 2 is not supplied to the output point of the above-described full bridge circuit, the choke coils 16 and 17, and the load 5.
This is because the two output points of the full bridge circuit constituted by the switch 11 (Q1) to the switch 14 (q2) are connected. In other words, one end of the choke coil 16 and one end of the choke coil 17 are connected to each other. 5 is supplied with the voltage VB from the boost power supply unit 3. At this time, the voltage V1 generated by the DC power supply unit 2 is not superimposed on the voltage VB.
Since the boost power supply unit 3 detects the voltage across the load 5 as described above and generates the voltage VB equal to the detected voltage Vs, there is no potential difference between the output points of the full bridge circuit. When the potential difference disappears in this way, the energy (electric power) accumulated in the choke coils 16 and 17 is released, and an inertial current flows through the load 5 by this energy.

FIG. 7 is an explanatory diagram showing the operation of the DC power supply device of FIG. This figure is a timing chart showing the ON / OFF state of each switch constituting the full bridge circuit of the current control unit 1, and state transition A showing one switch operation pattern and state transition showing another switch operation pattern. B.
In each state shown in FIG. 7, a high level portion represents an on state, and a low level portion represents an off state.
The state transition A represents, for example, the on / off operation of the switch 11 (Q1), and the state transition B represents the on / off operation of the switch 13 (q1).
Here, of the state transition A and the state transition B, the time width in the state transition with the shorter on-state period (narrow time width) is Tm, and the on-state of the state transition A and the on-state of the state transition B are When the overlapping period is Td, the ratio of the overlap period Td to the time width Tm is the drive overlap ratio Rd (Rd = Td / Tm). In the example illustrated in FIG. 7, a state transition A has a narrower time width in one state (here, an on state), and a state transition B has a wider time width in one state (on state). It is.

FIG. 7A shows a general switching operation that has been performed conventionally. For example, state transition A representing the operation pattern of the switch 11 (Q1) and state representing the operation pattern of the switch 13 (q1). Transition B is shown.
In the switch operation illustrated in FIG. 7A, the delay time (dead time) that occurs when each switch transitions from the on state to the off state, or from the off state to the on state, is very small. To the extent that it can be considered. Here, when the period in which the state transition A is at the low level and the period in which the state transition B is at the high level are each Tm, the period Td is regarded as “0”, thereby driving the drive. The overlapping rate Rd becomes Td / Tm = 0, and the above-described period of inertia current does not occur.
FIG. 7B shows an example of the switch operation under the control of the current control unit 1 of FIG. Similarly to FIG. 7A, the state transition A in FIG. 7B represents the operation pattern of the switch 11 (Q1), for example, and the state transition B represents the operation pattern of the switch 13 (q1). .

  In FIG. 7B, the time width on the high level side is narrower in the state transition B than in the state transition A. Further, the time transition on the low level side is narrower in the state transition A than in the state transition B. The narrower time width is Tm. Of the periods in which the state transition B is at the high level with the time width Tm, the period in which the state transition A is at the high level is Td. Of the periods in which the state transition A is at the low level with the time width Tm, the period in which the state transition B is at the low level is Td. Since the inertia current flows during the period Td, the period during which the inertia current flows becomes longer as the drive overlap ratio Rd increases.

In addition, the period during which the current flows is shortened by the voltage V1 generated by the DC power supply unit 2 symmetrically. In other words, the period in which the state transition A is in the on state and the state transition B is in the off state and the period in which the state transition A is in the off state and the state transition B is in the on state are shortened.
As described above, the current control unit 1 switches the input voltage (voltage V1) and suppresses the period during which the current is output, thereby suppressing the above-described triangular wave current (ripple current). By flowing an inertial current during a period in which no current is output from the control unit 1, a direct current flowing through the load 5 can be maintained.

  For example, when the power of 10 [kW] or more is output to the output load 5, the switch control unit 4 switches each switch of the current control unit 1 at 20 [kHz] or less (a cycle of 50 [μsec.] Or more). When the load 5 is light, it is switched at several hundreds [kHz]. Further, the on-duty of each switch is adjusted according to the power output to the load 5, and the control signal of each switch is set so that the aforementioned drive overlap ratio Rd = (Td / Tm) × 100% is, for example, 50% or more. And the full bridge circuit of the current control unit 1 is operated.

  In addition, when the aforementioned inertial current flows, the voltage VB is supplied from the boost power supply unit 3 to the second output point of the current control unit 1, and therefore the potential at the first output point and the second output point is the voltage VB. Thus, the inertia current flows in a state where the voltage VB is applied. When the inertial current flows in this way, the voltage VB is applied, so that the voltage Vc of the load 5 is apparently reduced, and is preferably 0 [V]. Since the switching operation is not performed during the period in which the inertia current flows, the generation of the triangular wave current is eliminated.

FIG. 8 is an explanatory diagram showing the operation of the full bridge circuit of the current control unit. The upper part of the figure is a graph showing the change over time of the current flowing in the first output point of the full bridge circuit constituting the current control unit 1 or the load 5, the vertical axis showing the current, and the horizontal axis showing the elapsed time. ing. The lower part of the figure shows the on / off operation of the switch 11 (Q1) and the on / off operation of the switch 13 (q1) among the switches constituting the full bridge circuit.
The on / off operation of the switch 12 (Q2) (not shown) is an inversion of the switch 11 (Q1), and the on / off operation of the switch 14 (q2) (not shown) is the switch 13 (q1). Will be reversed. The operation illustrated in FIG. 8 corresponds to the operation in FIG.
Here, the voltage at the first output point of the current control unit 1 or the full bridge circuit is V. Further, let L be the inductance of the current control unit 1 when viewed from the load 5, that is, the total inductance of the choke coils 16 and 17.

FIG. 9 is an explanatory diagram showing the operation of the DC power supply device of FIG. The same parts as those shown in FIG. 5 will be described using the same reference numerals.
When the current control unit 1 operates as shown in FIG. 6A and enters the first switch state shown in FIG. 9A, the current flowing from the current control unit 1 to the load 5 is I. The rate of change is dI / dt = (V−Vc) / L.
Further, when both the switch 11 (Q1) and the switch 13 (q1) are in the ON state as shown in FIG. 9B, or the switch 12 (Q2) and the switch 14 shown in FIG. 9C. When both (q2) are in the ON state, the current I decreases because no power is supplied from the DC power supply unit 2. The current change rate at this time is dI / dt = −Vc / L.
When the current I supplied to the load 5 is increased, in order to suppress the ripple current (triangular wave current), it is desirable to increase the current sharply and ideally eliminate the current decrease. That is, it is preferable that the voltage V is sufficiently larger than the voltage Vc to increase the current change rate, and the voltage Vc is small to reduce the current change rate.

From the above relationship, when the ripple current is suppressed in a circuit that does not include the boost power supply unit 3 as in the conventional power supply device, the inductance L provided in the current circuit is increased to increase the current change rate in the steady state. It is small. In order to improve the transient characteristics (response speed) during current control, a high voltage is applied to the current circuit to increase the current change rate. For this reason, a power supply voltage that is significantly higher than the voltage Vc across the load is required, and in general, a power supply voltage that is approximately five times the voltage Vc is often required.
When the power supply voltage is set as described above, when driving a battery or the like that outputs a high voltage of several hundred volts, an apparatus / equipment for handling a considerable high voltage is required. The technique of the present invention makes it possible to reduce the ripple current without requiring a high voltage far exceeding the voltage of the load.

Since the voltage output from the full bridge circuit when in the first switch state is V1 + VB, and the voltage VB is equal to the voltage Vc across the load 5, the current change rate is dI / dt = V1 / L. Become. At this time, the voltage Vc apparently becomes 0 [V] or a very small value, so that the voltage V1 is a voltage sufficiently larger (more than 5 times) than the voltage Vc.
Further, in the operation of FIG. 6A, when both the switch 11 (Q1) and the switch 13 (q1) are on, or both the switch 12 (Q2) and the switch 14 (q2) are on. When the voltage VB is applied, the voltage Vc of the load 5 is apparently 0 [V] by applying the voltage VB. Therefore, the portion of the current waveform shown in FIG. 8 where dI / dt = −Vc / L is ideal. , DI / dt = 0, and the falling portion of the triangular wave current does not occur. That is, the current supplied from the current control unit 1 to the load 5 increases stepwise. In other words, the current ripple component (triangular wave current) is not included.

When the operation of FIG. 6B not shown in FIG. 8 is performed, the switch 11 (Q1) and the switch 14 (q2) are in the off state, and the switch 12 (Q2) and the switch 13 (q1) are in the on state. When the current control unit 1 enters the second switch state, the polarity of the voltage V1 applied to the choke coils 16 and 17 is reversed. When the current at this time is I, the current change rate is dI / dt = (− V−Vc) / L.
When the current control unit 1 to which the voltage VB is supplied is in the second switch state as described above, the voltage −V output from the full bridge circuit is −V1 + VB, and apparently as described above. Since the voltage Vc = 0 [V], the current change rate is dI / dt = −V1 / L. Since the absolute value of the voltage −V1 at this time is sufficiently larger than the apparent voltage Vc, the current drop is steep.

  Further, in the operation of FIG. 6B, when both the switch 11 (Q1) and the switch 13 (q1) are in the ON state as in FIG. 9B, or in the same manner as in FIG. 9C. When both the switch 12 (Q2) and the switch 14 (q2) are in the ON state, the voltage Vc of the load 5 is apparently 0 [V] by applying the voltage VB. The rising portion of the current becomes dI / dt = 0 and does not occur. That is, the current flowing through the load 5 decreases stepwise and does not include ripple current (triangular wave current). Note that the current flowing in this operation flows in a direction opposite to the current I shown in FIGS. 9B and 9C.

As described above, the DC power supply device according to the first embodiment shortens the period in which the voltage is output from the DC power supply unit 2 and connects the two output points of the current control unit 1 to flow an inertial current. Ripple current generated in the current flowing through is suppressed. Furthermore, a voltage VB equal to the voltage Vc across the load 5 is supplied to the current control unit 1, and the current change rate when the two output points of the current control unit 1 are connected is reduced to reduce the ripple current (triangular wave). When the current control of the load 5 having a high voltage is performed from the DC power supply device, the ripple current can be regarded as having no current.
For example, when a current sensor or the like is provided between the current control unit 1 and the load 5 and the charge / discharge characteristics of the load 5 are measured from the current value measured using the current sensor, the ripple current is suppressed as described above. This makes it possible to accurately measure the charge / discharge characteristics of the load 5 having a high voltage.

Further, the DC power supply device according to the first embodiment includes the current control unit 1 having a full bridge circuit, so that the current flowing through the load 5 is increased and decreased using the DC power supply unit 2 that outputs a single voltage V1. In addition, it is possible to allow a current to flow from the current control unit 1 to the load 5 and to allow a current to flow from the load 5 to the current control unit 1. Further, as described above, the ripple current (triangular wave current) can be suppressed by providing the period for allowing the inertial current to flow by controlling the full bridge circuit.
Further, when the current sensor is provided as described above, since the ripple current included in the current detected by the current sensor becomes fine, the current flowing through the load 5 using the current value detected by the current sensor is reduced. Control with high accuracy is also possible.
When the load 5 is a battery or the like, when current flows from the current control unit 1 to the load 5 as described above, the load 5 is in a charged state, and each power supply unit performs a power output operation. When a current flows from the load 5 to the current control unit 1, the load 5 is in a discharge state, and each power supply unit operates as an electronic load. The DC power supply apparatus described in the first embodiment has a regeneration function and a function capable of operating as a bidirectional power supply.

(Example 2)
FIG. 10 is an explanatory diagram showing a schematic configuration of a DC power supply device according to Embodiment 2 of the present invention. The illustrated DC power supply includes a switch 31 (Q1) to a switch 34 (Q2) made of semiconductor switch elements, a choke coil 26 that removes a high-frequency component contained in a circuit current, an output capacitor 27 that smoothes a circuit voltage, and the like. A current control unit 21 including a switch control unit 24 that controls each switch operation of the switch 31 (Q1) to the switch 34 (Q2) is provided. Further, a DC power supply unit 22 that supplies DC voltages + V1 and −V1 to the current control unit 21 and a boost power supply unit 23 that supplies a boost voltage VB to the current control unit 21 are provided.
The DC power supply device shown in FIG. 10 is connected to a load 25 such as a battery pack that generates a DC voltage Vc.

The current control unit 21 includes a switch 31 (Q1), a switch 32 (q1), a switch 33 (q2), and a switch 34 (Q2) connected in series, and a voltage + V1 output from the DC power supply unit 22 at one end of the series connection. Is connected, and the other end is connected to the circuit so that the voltage -V1 from the DC power supply unit 22 is supplied.
The cathode of the diode 35 is connected to the connection point between the switch 31 (Q1) and the switch 32 (q1). The anode of the diode 36 is connected to the connection point between the switch 33 (q2) and the switch 34 (Q2). The anode of the diode 35 and the cathode of the diode 36 are connected to the ground (hereinafter referred to as GND) terminal of the DC power supply unit 22. Further, the high potential side output terminal of the voltage VB of the boost power supply unit 23 is connected to the GND terminal of the DC power supply unit 22.

One end of the choke coil 26 is connected to a connection point (output point) between the switch 32 (q1) and the switch 33 (q2). One end of an output capacitor 27 is connected to the other end of the choke coil 26, and a high potential side electrode of the load 25 is connected. Note that the other end of the output capacitor 27 is GND-connected.
The low potential side electrode of the load 25 is connected to the low potential side output terminal of the boost power supply unit 23. That is, the load 25 is connected to the boost power supply unit 23 in reverse polarity in series.
Both electrodes of the load 25 are connected to a voltage monitor terminal of the boost power supply unit 23 and the like.
The switches 31 (Q1) to 34 (Q2) are made of semiconductor switch elements such as MOSFETs, for example, and gates serving as control terminals are connected to the switch control unit 24, respectively.

The switch control unit 24 includes a processor, a memory, and the like. For example, the switch 31 (Q1) to the switch 34 according to a setting command input from the outside or according to a control program stored in its own internal memory. (Q2) is configured to be turned on and off, respectively.
The DC power supply unit 22 includes a power supply circuit that generates the voltage + V1 and the voltage −V1 as described above, and has a current capacity that does not change the voltage + V1 and the voltage −V1 when the load 25 is connected to the current control unit 21. Have.
The boost power supply unit 23 detects the voltage Vc across the load 25 and adjusts the magnitude of the boost voltage VB output to the current control unit 21 and the like according to the voltage Vs when the detected voltage is Vs. It is configured.

Next, the operation will be described.
The boost power supply unit 23 detects, for example, the voltage Vc across the load 25, generates a voltage VB equal to the detected voltage Vs, and supplies the high potential side voltage of the voltage VB to the current control unit 21, more specifically the DC power supply unit 22. Applied to the GND terminal. In other words, the boost power supply unit 23 outputs the voltage VB so that the voltage Vc of the load 25 connected to the current control unit 21 is apparently small from the current control unit 21 and is preferably 0 [V]. To do.
The DC power supply unit 22 supplies the voltage + V1 to one end of the switch 31 (Q1) and supplies the voltage −V1 to one end of the switch 34 (Q2).

The switch control unit 24 provides the transmission period and the pause period described in the first embodiment, and causes a current to flow between the current control unit 21 and the load 25. It should be noted that the on / off transition timing of each switch is different between the transmission period and suspension period described in the first embodiment and the transmission period and suspension period in the second embodiment. The period during which the OFF state overlaps is different.
The transmission period provided when the DC power supply device according to the second embodiment operates includes a current increase transmission period using the voltage + V1 and a current decrease transmission period using the voltage -V1.
In the DC power supply device of Example 2, each switch operation is controlled so that the length of each transmission period, that is, the on-duty of the voltage + V1 or the voltage −V1 is basically about 50 [%]. Therefore, the switch control is performed by setting the above-described on-duty so that the ripple current can be effectively suppressed.

The switch control unit 24 operates the switch 32 (q1) as follows.
i) It is turned on together with the switch 31 (Q1) to generate the above-described current increase transmission period, and the voltage + V1 output from the DC power supply unit 22 is connected to the output point of the current control unit 21 (switch 21 (q1)) To the switch 33 (q2)).
ii) In the above-described rest period in which the switch 31 (Q1) is turned off, when a current flows from the output point of the current control unit 21 to the high potential side electrode of the load 25, the switch 32 (q1) is turned on. Thus, a current circuit in which the choke coil 26, the load 25, the boost power supply unit 23, and the diode 35 are connected in series is formed. In this current circuit, due to the energy accumulated in the choke coil 26, an inertial current (charging current) from the current control unit 21 (choke coil 26) to the load 25 flows.
iii) When the switch 34 (Q2) and the switch 33 (q2) are turned on and the current reduction transmission period is reached, the voltage applied to the current control unit 21 is not damaged. It becomes.

The switch control unit 24 operates the switch 33 (q2) as follows.
i) Turns on together with the switch 34 (Q2) to generate the above-described current decrease transmission period and supply the voltage -V1 output from the DC power supply unit 22 to the output point of the current control unit 21.
ii) In the above-described rest period in which the switch 34 (Q2) is turned off, when a current is passed from the load 25 to the current control unit 21, the switch 34 (q2) is turned on and the choke coil 26 and the load 25 are turned on. The boost power supply unit 23 and the diode 36 form a current circuit connected in series. In this current circuit, due to the energy accumulated in the choke coil 26, an inertial current (discharge current) from the load 25 to the current control unit 21 (choke coil 26) flows.
iii) When the switch 31 (Q1) and the switch 32 (q1) are turned on and the above-described current increase transmission period is reached, the voltage applied to the current control unit 21 is not damaged. It becomes.
The control logic of each switch as described above enables an operation substantially similar to that of the DC power supply device described in the first embodiment.

  Since the boost power supply unit 23 detects the voltage Vc across the load 25 as described above and generates the voltage VB so as to be equal to the voltage Vc, there is no potential difference across the choke coil 26 at this time. The voltage Vc viewed from the current control unit 21 becomes small and ideally becomes 0 [V].

As described above, when the voltage Vc is apparently reduced, the aforementioned current change rate dI / dt = −Vc / L is also reduced, and preferably none at all. That is, during such a switch state, the amount of current flowing through the current control unit 21 is extremely small, and is substantially constant.
For example, the switch controller 24 controls both the switch 31 (Q1) and the switch 32 (q1) from the switch state where the voltage + V1 output from the DC power supply unit 22 is not supplied to the choke coil 26, and the voltage + V1 Is supplied to the choke coil 26, and either or both of the switch 33 (q2) and the switch 34 (Q2) are controlled to be in an off state so that the voltage -V1 is not applied to the choke coil 26. In the increase transmission period, the current flowing from the current control unit 21 to the load 25 increases steeply.
Thereafter, during the period when the switch 31 (Q1) is turned off and the switch 32 (q1) is maintained in the on state (rest period), the energy accumulated in the choke coil 26 is formed by the current circuit described above. As a result, an inertial current flows, and the current change (decrease) after the supply of the voltage + V1 is cut off is suppressed to a small level. That is, for example, when the charging current of the load 25 is increased, the current flowing from the current control unit 21 to the load 25 increases stepwise, and a triangular wave current (ripple current) that repeatedly increases and decreases is not observed.

Further, the switch control unit 24 controls both the switch 33 (q2) and the switch 34 (Q2) from the switch state in which the voltage −V1 output from the DC power supply unit 22 is not supplied to the choke coil 26 to turn on the voltage. -V1 is supplied to the choke coil 26, and either or both of the switch 31 (Q1) and the switch 32 (q1) are controlled to be off so that the voltage + V1 is not applied to the choke coil 26. When the current decrease transmission period is set, the current flowing through the load 25 decreases sharply.
After that, the switch 34 (Q2) is changed to the OFF state, and the current circuit is formed and the energy stored in the choke coil 26 during the period in which the switch 33 (q2) is maintained in the ON state (rest period). As a result, an inertial current flows, and the current change (decrease) after the supply of the voltage -V1 is cut off is suppressed to a small level. That is, for example, when the charging current of the load 25 is decreased, the current flowing through the load 25 decreases stepwise, and a triangular wave current (ripple current) that repeatedly increases and decreases is not observed.

Note that the DC power supply device according to the second embodiment includes a regenerative function and a function capable of operating as a bidirectional power supply in the same manner as the DC power supply device described in the first embodiment.
When the discharge current of the load 25 is controlled by the DC power supply device of the second embodiment, the switch control for supplying the voltage −V1 is performed when the discharge current is increased, and the switch control for supplying the voltage + V1 is performed when the discharge current is decreased. I do.
For example, when supplying power of 10 [kW] or more to the output load 25, the switch control unit 24 switches each switch of the current control unit 21 at 20 [kHz] or less. That is, the current flowing through the load 25 is 50 [μsec. ] Ascending or descending stepwise in the above cycle. When the load 25 is light, it may be switched at several hundred [kHz].

As described above, the direct-current power supply device according to the second embodiment reduces the apparent voltage Vc of the load 25 so that the current control unit 21 applies a positive or negative voltage to the load 25. When the current flowing from the control unit 21 to the load 25 or from the load 25 to the current control unit 21 is sharply changed and the voltage generated by the DC power supply unit 22 is not applied to the load 25, the rate of change of the current flowing through the current control unit 21 By making the current smaller, the generation of a triangular wave current (ripple current) is suppressed by changing the current stepwise when the current rises or falls.
For example, when a current sensor or the like is provided between the current control unit 2 and the load 25 and the charge / discharge characteristics of the load 25 are measured from the current value measured using the current sensor, the ripple current is suppressed as described above. This makes it possible to accurately measure the charge / discharge characteristics of the load 25 having a high voltage.
In addition, when the current sensor is provided as described above, the ripple current included in the current detected by the current sensor becomes fine, so the current flowing through the load 25 using the current value detected by the current sensor is reduced. Control with high accuracy is also possible.

1,21 current control unit 2,22 DC power supply unit 3,23 boost power supply unit 4,24 switch control unit 5,25 load 11-14,31-34 switch 16,17,26 choke coil 18,27 output capacitor 35, 36 diodes 101 and 102 switches 103 and 124 choke coils 104 smoothing capacitors 105 loads 110 to 113 switches 114 and 115 diodes

A DC power supply device according to the present invention is connected to a load having a DC voltage, and uses a plurality of switch elements to control a current flowing through the load, and a first DC voltage smaller than a voltage across the load. And a second power source that generates a second DC voltage equal to the voltage across the load, and the load and the second power source. The first power supply unit is connected in series via the current control unit between the load and the second power supply unit in reverse polarity series, and the operation of each switch element of the current control unit The first DC voltage is superimposed on the second DC voltage with a predetermined on-duty and supplied to the load.

The current control unit connects one end of the first switch element and one end of the second switch element in series, connects one end of the third switch element and one end of the fourth switch element in series, and is connected in series. A full bridge circuit formed by connecting in parallel the first and second switch elements and the third and fourth switch elements connected in series;
(1) A connection point connecting the other end of the first switch element and the other end of the third switch element is a first connection point,
(2) A connection point connecting the other end of the second switch element and the other end of the fourth switch element is a second connection point,
(3) A connection point connecting one end of the first switch element and one end of the second switch element is a third connection point,
(4) A connection point connecting one end of the third switch element and one end of the fourth switch element is a fourth connection point,
(5) When the first connection point and the second connection point are input points of the full bridge circuit, and the third connection point and the fourth connection point are output points of the full bridge circuit,
A capacitor that connects the output points; a choke coil that connects the output point and the capacitor; and a switch control unit that controls on / off operations of the fourth switch element from the first switch element; The output terminal of the first power supply unit is connected so that the first DC voltage is supplied between the input points, and the high potential side voltage of the load is applied to the third connection point. The second power supply unit is connected to the other end of the capacitor such that a high potential side electrode of the load is connected to one end of the capacitor, and a high potential side voltage of the second DC voltage is supplied to the fourth connection point. Are connected to the low potential side output terminal of the second power supply unit , and the switch control unit includes the first switch element and the third switch element. Of the switch elements The on-off state of the switch element with the narrower on-state time width is Tm, the on-off state of the switch element with the wider on-state time width and the on-off state of the switch element with the narrower on-state time width When the overlap period in which the state is the same is Td, and the drive overlap ratio indicating the ratio of the overlap period Td to the time width Tm is Rd = (Td / Tm) × 100%, the drive overlap ratio Rd is 50%. The operation of each switch element is controlled so as to be 100% or less, the first switch element and the second switch element are alternately turned on / off, and the third switch element and the fourth switch element are alternately switched. The supply current supplied from the full bridge circuit to the load is output, and the first switch element and the third switch are output during a period when the supply current is not output. Both the switch elements are turned on to connect between the third connection point and the fourth connection point, and an inertial current flows.

The current control unit is connected to the first switch element, the second switch element, the third switch element, and the fourth switch element that are connected in series, and at a connection point between the second switch element and the third switch element. The other end of the choke coil is connected to the other end of the choke coil, the other end of the choke coil is connected to the ground, and the other end of the choke is grounded. A switch control unit for controlling on / off operation of the switch element; a first diode for connecting a cathode to a connection point between the first switch element and the second switch element; the third switch element; and the fourth switch element. A second diode for connecting an anode to a connection point with the switch element, and the first power supply unit generates a first DC voltage having a positive voltage polarity and a first DC voltage having a negative voltage polarity. The positive first DC voltage output terminal is connected to one end of the first switch element, the negative first DC voltage output terminal is connected to one end of the fourth switch element, and the positive first DC voltage output terminal is connected to one end of the fourth switch element. An output terminal serving as a center potential of one DC voltage and the negative first DC voltage is connected to the anode of the first diode and the cathode of the second diode, and is grounded. A high-voltage side output terminal of a DC voltage is connected to an output terminal serving as a central potential of the first power supply unit, and a low-voltage side output terminal of the second DC voltage is connected to a low-potential side electrode of the load; The switch control unit controls the first and second switch elements to be in an ON state, supplies the positive first DC voltage to the choke coil, sharply increases a current flowing through the load, and then It turns off the first switch element So transferred, said second switching element in the ON state, the choke coil, the inertial current by the second power supply unit and the energy that has accumulated in the choke coil to form a current circuit including a first diode to the load First control to flow, control the third and fourth switch elements to ON state, supply the negative first DC voltage to the choke coil to sharply reduce the current flowing to the load, and then The fourth switch element is changed to an off state, and a current circuit including the third switch element in the on state, the choke coil, the second power supply unit, and the second diode is formed and accumulated in the choke coil. And a second control for flowing an inertial current due to energy to the load.

The switch control unit 24 operates the switch 32 (q1) as follows.
i) It is turned on together with the switch 31 (Q1) to generate the above-described current increase transmission period, and the voltage + V1 output from the DC power supply unit 22 is connected to the output point of the current control unit 21 (switch 32 (q1)) To the switch 33 (q2)).
ii) In the above-described rest period in which the switch 31 (Q1) is turned off, when a current flows from the output point of the current control unit 21 to the high potential side electrode of the load 25, the switch 32 (q1) is turned on. Thus, a current circuit in which the choke coil 26, the load 25, the boost power supply unit 23, and the diode 35 are connected in series is formed. In this current circuit, due to the energy accumulated in the choke coil 26, an inertial current (charging current) from the current control unit 21 (choke coil 26) to the load 25 flows.
iii) When the switch 34 (Q2) and the switch 33 (q2) are turned on and the current reduction transmission period is reached, the voltage applied to the current control unit 21 is not damaged. It becomes.

Claims (4)

A current control unit connected to a load having a DC voltage and controlling a current flowing through the load using a plurality of switch elements;
A first power supply unit that generates a first DC voltage smaller than a voltage across the load and inputs the first DC voltage to the current control unit;
A second power source that generates a second DC voltage equal to the voltage across the load;
With
The load and the second power supply unit are connected in reverse polarity in series, and the first power supply unit is connected in series via the current control unit between the load and the second power supply,
The first DC voltage is superimposed on the second DC voltage with a predetermined on-duty by the operation of each switch element of the current control unit, and supplied to the load.
A direct current power supply device. The current controller is
One end of the first switch element and one end of the second switch element are connected in series, one end of the third switch element and one end of the fourth switch element are connected in series, and the first and second switch elements connected in series And a full bridge circuit in which the third and fourth switch elements connected in series are connected in parallel,
(1) A connection point connecting the other end of the first switch element and the other end of the third switch element is a first connection point,
(2) A connection point connecting the other end of the second switch element and the other end of the fourth switch element is a second connection point,
(3) A connection point connecting one end of the first switch element and one end of the second switch element is a third connection point,
(4) A connection point connecting one end of the third switch element and one end of the fourth switch element is a fourth connection point,
(5) When the first connection point and the second connection point are input points of the full bridge circuit, and the third connection point and the fourth connection point are output points of the full bridge circuit,
A capacitor connecting between the output points;
A choke coil connecting between the output point and the capacitor;
A switch controller for controlling on / off operations of the fourth switch element from the first switch element;
With
An output terminal of the first power supply unit is connected so that the first DC voltage is supplied between the input points,
A high potential side electrode of the load is connected to one end of the capacitor so that a high potential side voltage of the load is applied to the third connection point;
A high-potential-side output terminal of the second power supply unit is connected to the other end of the capacitor so that a high-potential-side voltage of the second DC voltage is supplied to the fourth connection point;
A low potential side electrode of the load is connected to a low potential side output terminal of the second DC power supply unit;
The switch control unit
Of the first switch element and the third switch element, the smaller time width of the ON state is Tm, and the ON / OFF state of the switch element having the wider on state time is the ON / OFF state. Td is the overlap period in which the ON / OFF state of the switch element with the narrower time width is the same, and the drive overlap ratio indicating the ratio of the overlap period Td to the time width Tm is Rd = (Td / Tm) × When 100%, the operation of each switch element is controlled so that the drive overlap ratio Rd is 50% or more and 100% or less,
Supplying from the full bridge circuit to the load by alternately turning on and off the first switch element and the second switch element and alternately turning on and off the third switch element and the fourth switch element Output current,
In a period in which the supply current is not output, the first switch element and the third switch element are both turned on to connect the third connection point and the fourth connection point to flow an inertia current.
The DC power supply device according to claim 1. The current controller is
A first switch element, a second switch element, a third switch element and a fourth switch element connected in series;
A choke coil having one end connected to a connection point between the second switch element and the third switch element and the other end connected to a high potential side electrode of the load;
A capacitor that connects one end to the other end of the choke coil and grounds the other end;
A switch controller for controlling on / off operations of the fourth switch element from the first switch element;
A first diode connecting a cathode to a connection point between the first switch element and the second switch element;
A second diode connecting an anode to a connection point between the third switch element and the fourth switch element;
With
The first power supply unit
A first DC voltage having a positive voltage polarity and a first DC voltage having a negative voltage polarity;
Connecting the output terminal of the positive first DC voltage to one end of the first switch element;
Connecting the output terminal of the negative first DC voltage to one end of the fourth switch element;
An output terminal serving as a center potential of the positive first DC voltage and the negative first DC voltage is connected to the anode of the first diode and the cathode of the second diode, and is grounded.
The second power supply unit
A high-potential side output terminal of the second DC voltage is connected to an output terminal serving as a center potential of the first power supply unit;
A low potential side output terminal of the second DC voltage is connected to a low potential side electrode of the load;
The switch control unit
The first and second switches are controlled to be in an on state, the positive first DC voltage is supplied to the choke coil, the current flowing through the load is sharply increased, and then the first switch is transitioned to an off state. A current circuit including the second switch, the choke coil, the second power supply unit, and the first diode in an on state is formed, and an inertial current due to energy accumulated in the choke coil is caused to flow to the load. 1 control,
The third and fourth switches are controlled to be in an on state, the negative first DC voltage is supplied to the choke coil, the current flowing through the load is sharply reduced, and then the fourth switch is transitioned to an off state. A current circuit including the third switch, the choke coil, the second power supply unit, and the second diode in an on state is formed, and an inertial current due to energy accumulated in the choke coil is caused to flow to the load. 2 control,
The DC power supply device according to claim 1, wherein: The second power supply unit detects a voltage across the load and generates a second DC voltage equal to the detected voltage;
The DC power supply device according to any one of claims 1 to 3, wherein

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