JP2002238250A - Symmetrical dc/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a symmetrical DC/DC converter capable of optionally selecting a conveying direction of energy and optionally setting step-up and step-down including their ratios. SOLUTION: In the symmetrical DC/DC converter, a pair of switching means 53, 53 is connected to respective terminals of one inductor 23 so as to be symmetrical with respect to the inductor 23. The DC/DC converter is structured so as to operate a step-up converter and a step-down converter with one of the pair of switching means 53, 53 taken as an input and the other taken as an output, and so as to operate the step-up converter and the step-down converter with the input taken as an output and the output as an input as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC converter for transmitting electric energy by increasing or decreasing a voltage, and more particularly to a symmetric DC / DC converter.

[0002]

2. Description of the Related Art For example, an electric double layer capacitor is known as an energy storage device whose voltage varies according to the amount of stored energy. When an electric double layer capacitor is used, it is necessary to transfer energy by increasing or decreasing the voltage when charging or discharging.

When a motor such as an electric vehicle is used as a load that consumes electric power of an electric double layer capacitor, the energy efficiency of the entire system is reduced by collecting the energy when the motor generates power in reverse, such as during braking. Greatly increase.

In order to increase or decrease the voltage, DC /
It is important for the function of the DC converter to be able to transfer energy to the other, regardless of the input of energy. A method of preparing a DC / DC converter for each direction and switching with a switch is conceivable, but this is not practical because the whole device becomes large. Therefore, the DC / D functioning even if the input and output are switched in one circuit
A C converter is indispensable.

Conventionally, as this type of DC / DC converter, a so-called bidirectional converter has been proposed. This conventional bidirectional DC / DC converter is a circuit element having four terminals for connecting a charger or a power supply, for example, an electric double layer capacitor, and a load, for example, a motor.

FIG. 12 is a circuit diagram showing a configuration example of a conventional bidirectional DC / DC converter (hereinafter, referred to as prior art 1). Referring to FIG. 12, in the bidirectional DC / DC converter, when power is supplied from the electric double layer capacitor 17 to the motor 19 to operate the motor 19, the switch circuit 29 is opened and the switch circuit 27 is operated. It is controlled by PWM or the like, and is operated as a forward type converter circuit.

When the electric power generated by the motor 19 is supplied to the electric double layer capacitor 17 for charging, the switch circuit 27 is opened and the switch circuit 29
It is controlled by M or the like, and is operated as a forward type converter circuit.

FIG. 13 is a circuit diagram showing another configuration example of a conventional bidirectional DC / DC converter (see Japanese Patent Application Laid-Open No. 2000-33445, hereinafter referred to as Conventional Technique 2).

Referring to FIG. 13, a bidirectional DC / DC converter according to the prior art 2 is provided between a DC power supply 33 and a load 37 including a capacitor 35. Conventional technology 2
The bidirectional DC / DC converter 31 uses an FET as a switch element, and specifically includes a first series circuit 43, a second series circuit 49, the inductance 23, and a control device (not shown). The first series circuit 43 includes a first FET 39 and a second FET
41. The second series circuit 49 includes a third FET 45 and a fourth FET 47 connected in parallel to the load. The inductance 23 includes the first FET 39 and the second FE
It is provided between a connection point with T41 and a connection point between the third FET 45 and the fourth FET 47. Further, the control device
Supplying the energy of the DC power supply 33 to the load 37;
The first FET 39, the second FET 41, the third FET 45, and the fourth F 4 are connected so that the energy stored in the capacitor 35 is regenerated to the DC power supply 33.
This is a configuration for controlling each gate of the ET47.

[0010]

The bidirectional converter of the prior art 1 has a plurality of inductors and a complicated circuit configuration.

In addition, when an energy storage device whose voltage varies like a capacitor is used for the electric double layer, or when driving / regeneration is performed by a motor load, a system including a voltage change amount corresponding to the energy amount is provided. Become. Therefore, it is necessary not only to transfer energy in either direction, but also to be able to freely raise or lower the voltage depending on which voltage is higher or lower.

Further, when constructing a system by combining a plurality of energy storage devices, generators and loads, it is necessary to appropriately set the step-up ratio and step-down ratio.
Conventional bidirectional converters could not cope.

It is an object of the present invention to provide a symmetric DC / DC converter that operates at a step-up ratio or a step-down ratio corresponding to a direction corresponding to energy transfer and an input / output voltage ratio. .

[0014]

According to the present invention, a DC / D converter in which a pair of switch means is connected to each terminal of one inductor so as to be symmetrical with respect to the inductor.
C converter, wherein one of the pair of switch means is input and the other is output to operate as a boost converter and a step-down converter, and the input is an output and the output is an input. Symmetrical shape D characterized by being able to operate as
A C / DC converter is provided.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a circuit diagram of a symmetric DC / DC converter according to a first embodiment of the present invention.

Referring to FIG. 1, a symmetric DC / DC converter 51 according to a first embodiment of the present invention has a pair of switch means 53 connected to an inductor 23. By controlling the switch means 53, 53, the input / output direction of the apparatus and the step-up and step-down are selected.

FIG. 2 is a circuit diagram of a symmetric DC / DC converter according to a second embodiment of the present invention. FIG. 3 is FIG.
FIG. 5 is a configuration diagram when a boost operation is performed using third and fourth terminals of the symmetric DC / DC converter of FIG. FIG. 4 shows FIG.
FIG. 4 is a configuration diagram when a step-down operation is performed using third and fourth terminals of the symmetric DC / DC converter of FIG.

Referring to FIG. 2, a symmetric DC / DC converter 55 according to a second embodiment of the present invention includes switch portions 57, 59 and 61, 63 at both ends of inductor 23.
And one end of each switch section 57, 59 and 61, 6
3 are connected to terminals 65, 67, 69, 71, respectively, and capacitors 73, 73 are inserted between the switches 57, 59 and 61, 63, respectively. Are connected to form four terminals.

Table 1 below shows the first and second terminals 6.
5 and 67 are input and the third and fourth terminals 69 and 71 are output, and the first and second terminals 65 and 67 are output and the third
The operation is collectively shown separately for the case where the signals are input to the fourth terminals 69 and 71.

[0021]

[Table 1]

In the above Table 1, the switches 57, 5
9, 61, and 63, the operation is shown in Table 1 above, “ON” is a short-circuit state, “OFF” is an open state,
"SW" indicates a state in which ON-OFF is performed intermittently so as to attain an appropriate step-up ratio or step-down ratio by, for example, PWM control, and "D" indicates a rectifying operation.

Referring to FIG. 3, the first and second terminals 6
The symmetric DC / DC converter of the present invention is operated as a step-up converter with 5,67 as input and the third and fourth terminals 69,71 as output.

The switch section 57 is "ON", short-circuited, the switch section 59 is "OFF", it is open, and the switch section 61 is "D", so that the diode 75 performs rectifying operation, and the switch section 63 is "SW". , The switch circuit 77 is provided, and control is performed so that an appropriate boosting ratio is obtained.

Referring to FIG. 4, similarly to FIG. 2, the first and second terminals 65 and 67 are input, and the third and fourth terminals 69 and 7 are input.
1 as an output, the symmetric DC / DC converter according to the second embodiment of the present invention is operated as a step-down converter.

Since the switch section 57 is “SW”, the switch circuit 77 controls the switch circuit 77 so as to have an appropriate step-down ratio. Further, since the switch section 59 is “D”, it functions as a diode 75 that performs a rectifying operation. Since the switch section 61 is “ON”, it is short-circuited, and the switch section 63 is “OFF”.
Because it is open.

The first and second terminals 65 and 67 are output,
Also, when the fourth terminals 69 and 71 are input, the same operation can be realized only by switching the operation of the switch units 57 and 59 and 61 and 63, respectively.

FIG. 5 is a circuit diagram showing a symmetric DC / DC converter according to a third embodiment of the present invention. Referring to FIG. 5, a symmetrical D according to a third embodiment of the present invention
The C / DC converter 55 includes the switch units 57 and 5 shown in FIG.
9, 61 and 63 are provided with a configuration in which a switch circuit 77 and a rectifier 75 are connected in parallel.

Table 2 below shows that the first and second terminals 65 and 67 are input to the symmetric DC / DC converter of FIG.
When the third and fourth terminals 69 and 71 are output,
And the second and third terminals 65 and 67 are output.
9 and 71 as input, and
In each case, the operation of the switch unit is collectively shown for the case of stepping up or stepping down.

[0030]

[Table 2]

In Table 2 above, when the switch circuit 77 is set to the open operation "OFF", the diode 75 is connected in parallel, and the operation of the switch unit is the rectification operation "D".
Becomes Therefore, the opening operation “OF” in Table 1 is performed.
All parts of "F" are replaced with the rectifying operation "D" in Table 2 above.

However, the portion where the opening operation is changed to the rectifying operation is equivalent to the opening operation since no voltage is applied to the diode of the switch section in the forward direction.
The same operations as those shown in Table 1 above can be performed.

Therefore, in the symmetric DC / DC converter of FIG. 5, the same operation as that shown in Table 1 can be realized only by turning ON / OFF the switch circuit 77.

FIG. 6 is a circuit diagram showing a symmetric DC / DC converter according to a fourth embodiment of the present invention. Referring to FIG. 6, a symmetric D according to a fourth embodiment of the present invention is shown.
In the C / DC converter, a case is shown in which an FET 81 is used as the switch circuit 77 shown in FIG.
The body diode 83 of T81 can be used as a rectifier.

However, as shown in FIG. 6, if a high-performance diode 75 having a lower forward voltage Vf and a shorter recovery time than the body diode 83 is connected in parallel to the body diode 83 of the FET 81 in the same direction, respectively, Can be operated as a symmetric DC / DC converter without any influence.

FIG. 7 is a circuit diagram showing a symmetric DC / DC converter according to a fifth embodiment of the present invention. Referring to FIG. 7, a symmetric D according to a fifth embodiment of the present invention is shown.
In the C / DC converter, the DC / DC shown in FIG.
The diode operation of the converter is realized by synchronous rectification to improve the efficiency.

Specifically, in the fifth embodiment, the diode 21 is connected to the FET 8 so that the output of the operational amplifier 89 does not saturate to the negative side and analog control can be performed.
1 is connected to one end via a resistor 87.

As described above, according to the first to fifth embodiments of the present invention, the direction of the energy transfer can be freely selected, and the operation can be performed by freely changing the ratio between the step-up and step-down. A symmetric DC / DC converter can be provided.

FIG. 8 is a circuit diagram of a symmetric DC / DC converter according to a sixth embodiment of the present invention. FIG. 9 is a flowchart showing the operation of the symmetric DC / DC converter according to the sixth embodiment of the present invention.

Referring to FIG. 8, a symmetric DC / DC converter 91 according to a sixth embodiment of the present invention has a structure of a device for transferring energy which is different from that of the symmetric DC / DC converter according to the second embodiment. The same is true. The electric double layer capacitor 17, the solar cell 93, and the light emitting element 95 are connected as an example of an energy storage device for transferring energy, a power generation device, and a load. The control device 97 includes a voltage monitor 99,
The voltage information of each terminal from 101 is supplied to the current sensors 103, 1
05, the current information of each terminal can be obtained. Further, the control device has a function of judging the situation based on the information, and a state in which the switches 57, 59, 61, and 63 can be opened and short-circuited at high speed, a short-circuited state, an open state, and a current can flow in one direction. It is connected so that it can be controlled to any of the commutation states.

Referring to FIG. 9, in symmetric DC / DC converter 91 according to the sixth embodiment of the present invention, the states of switches 57, 59, 61, 63 are controlled by control device 97. The control device 97 controls the voltage information from the voltage monitors 99 and 101 and the current sensor 10.
The current information from Steps 3 and 105 (Step SA1) is determined (Step SA2), and it is determined which terminal is to be used for input and output, and whether to operate as a boost converter or a step-down converter (Step SA3). ).

When the direction of the energy transfer and the step-up / step-down voltage are determined, the switches 57, 59, 61 and 63 are set so as to operate as shown in Table 3 below, and the switch which operates the SW is operated. Is set to an appropriate value according to the input / output voltage ratio (step SA).
4). After the energy transfer (step SA5), the control device again determines the voltage information from the voltage monitors 99 and 101 and the current information from the current sensors 103 and 105 (step SA6). It is determined whether or not the operation should be performed, and the operation is normally repeated unless a termination instruction is given.

[0043]

[Table 3]

In the case of the sixth embodiment of the present invention, a configuration is provided in which not only the power generated by the solar cell 93 is consumed by the light emitting element 95 but also the surplus power is charged into the electric double layer capacitor 17. The control device 75 determines that the operation of charging the electric double layer capacitor 17 is performed while the solar cell 93 is generating power until the light emitting element 95 can emit light sufficiently. At this time, the electric double layer capacitor 17
Whatever the energy state or voltage value of
Control device 97 determines the input and output voltages to determine the step-up and step-down, and charges electric double layer capacitor 17. Further, when the light emitting element 95 is desired to emit light even when the solar cell 93 is not generating power, the voltage of the electric double layer capacitor 17 is set to an appropriate voltage regardless of whether the voltage is higher or lower than the voltage required for the light emitting element 95 to emit light. By adjusting and discharging the light-emitting element 95, the light-emitting element 95 can emit light with required luminance.

FIG. 10 is a circuit diagram of a symmetric DC / DC converter according to a seventh embodiment of the present invention. FIG. 11 is a flowchart showing the operation of the symmetric DC / DC converter according to the seventh embodiment of the present invention.

Referring to FIG. 10, in the symmetric DC / DC converter according to the seventh embodiment of the present invention, the configuration of the device for transferring energy is the same as that of the symmetric DC / DC converter according to the third embodiment. It is. An electric storage device, a power generation device, an electric double layer capacitor 17 and a motor 19 are connected as an example of a load. The control device 97 receives the voltage information of each terminal from the voltage monitors 99 and 101, From 105, current information of each terminal can be obtained.

The motor 19 required by the user
Can be obtained via the torque setting device 107. Further, the control device 97 has a function of judging the situation from the information.
Is connected so that it can be controlled to any of a state in which open and short circuits can be switched at high speed, a short circuit state, and an open state.

Referring to FIG. 11, in the symmetric DC / DC converter according to the seventh embodiment of the present invention,
The state of the switch circuit 77 is controlled by the control device 97. The control device 97 determines the voltage information from the voltage monitors 99 and 101, the current information from the current sensors 103 and 105, and the information input from the outside, that is, the information on the required torque from the torque setting device 107 here. (Step SB1, SB2, SB3), and determine which terminal the input and output are to be used (step SB4), and determine whether to operate as a boost converter or a step-down converter (step SB5).

When the direction of the energy transfer and the step-up / step-down voltage are determined, the state of the switch circuit 77 is set so that the switches 57, 59, 61, and 63 operate in accordance with the following Table 4 in accordance with the determined direction, and the operation of SW The interval between the open and short circuits of the switch circuit of the switch unit is set to an appropriate value in accordance with the ratio of the input and output voltages (step SB6). After the energy transfer (step SB7), the control device 97 determines again the voltage information from the voltage monitors 99 and 101 and the current information from the current sensor, and determines how to operate (step SB7). SB8).

[0050]

[Table 4]

In the case of the seventh embodiment of the present invention, an external signal is used as the torque of the motor 19 desired by the user, and the motor 1 in which the desired torque is actually operating is used.
In the case where the torque is smaller than the torque of the motor 9, for example, when the motor 19 is rotating and it is desired to stop the rotation, the motor 19 acts as a power generator. At this time, no matter what the energy state of the electric double layer capacitor 17, that is, the voltage value, or whatever the voltage value output from the motor 19, the control device 97 determines the input and output voltages and boosts the voltage. Then, the voltage drop is determined, and the electric double layer capacitor 17 is charged. When the desired torque is larger than the torque of the motor 19 that is actually operating, for example, when the motor 19 is stopped and a certain amount of rotation is desired, the motor 19 acts as a load. Whether the voltage of the electric double layer capacitor 17 is higher or lower than the voltage required for the operation of the motor 19, the motor 19 can be driven by adjusting the voltage to an appropriate voltage.

[0052]

As described above, according to the present invention,
Symmetric DC / D operating at a direction corresponding to the energy transfer and a step-up ratio or step-down ratio corresponding to the input / output voltage ratio
A C converter can be provided.

[Brief description of the drawings]

FIG. 1 shows a symmetric DC / DC according to a first embodiment of the present invention.
It is a circuit diagram of a DC converter.

FIG. 2 shows a symmetric DC / according to a second embodiment of the present invention.
It is a circuit diagram of a DC converter.

FIG. 3 is a configuration diagram of the symmetric DC / DC converter of FIG. 2 when a boost operation is performed using third and fourth terminals as inputs.

FIG. 4 is a configuration diagram of the symmetric DC / DC converter of FIG. 2 when a step-down operation is performed using third and fourth terminals as inputs.

FIG. 5 shows a symmetric DC / according to a third embodiment of the present invention.
FIG. 3 is a circuit diagram illustrating a DC converter.

FIG. 6 shows a symmetric DC / according to a fourth embodiment of the present invention.
FIG. 3 is a circuit diagram illustrating a DC converter.

FIG. 7 shows a symmetric DC / according to a fifth embodiment of the present invention.
FIG. 3 is a circuit diagram illustrating a DC converter.

FIG. 8 shows a symmetric DC / according to a sixth embodiment of the present invention.
It is a circuit diagram of a DC converter.

FIG. 9 shows a symmetric DC / according to a sixth embodiment of the present invention.
It is a flowchart figure showing operation | movement of a DC converter.

FIG. 10 shows a symmetric DC according to a seventh embodiment of the present invention.
It is a circuit diagram of a / DC converter.

FIG. 11 shows a symmetric DC according to a seventh embodiment of the present invention.
It is a flowchart figure showing operation | movement of / DC converter.

FIG. 12 is a circuit diagram showing a configuration of a bidirectional DC / DC converter according to Conventional Technique 1.

FIG. 13 is a circuit diagram showing a configuration of a bidirectional DC / DC converter according to Conventional Technique 2.

[Explanation of symbols]

 17 Electric Double Layer Capacitor 19 Motor 23 Inductance 27 Switch Circuit 29 Switch Circuit 31 Bidirectional DC / DC Converter 33 DC Power Supply 35 Capacitor 37 Load 39 First FET 41 Second FET 43 First Series Circuit 45 Third FET 47 Fourth FET 49 Second Series Circuit 51 Symmetric DC / DC converter 53 Switching means 55 Symmetric DC / DC converter 57, 59, 61, 63 Switch section 65, 67, 69, 71 Terminal 73 Capacitor 75 Diode (rectifier) 77 Switch circuit 81 FET 83 Body diode 87 Resistance 89 Operational amplifier 91 Symmetric DC / DC converter 93 Solar cell 95 Light emitting element 97 Controller 99, 101 Voltage monitor 103, 105 Current sensor 107 Torque setting device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H730 AA06 AS04 AS05 AS17 BB13 BB14 FD01 FD11 FD31 FD41 FG05 FG16 FG23

Claims (8)

[Claims] 1. A DC / DC converter in which a pair of switch means are connected to respective terminals of one inductor so as to be symmetrical with respect to the inductor, and one of the pair of switch means is connected to each other. Operates as a boost converter and a buck converter with the input and the other as output,
A symmetric DC / DC converter characterized in that it can operate as a boost converter and a step-down converter even when the input is an output and the output is an input. 2. The symmetric DC / DC converter according to claim 1, wherein two terminals connected in series by connecting one terminal of an inductor to an intermediate terminal of two switch units connected in series. Capacitors are connected in parallel to both terminals of the switch units to constitute the two terminals as input terminals or output terminals of a symmetric DC / DC converter, and similarly connected in series with another terminal of the inductor. An intermediate terminal of the two switch units is connected, a capacitor is connected in parallel to both terminals of the two switch units connected in series, and the two terminals are connected to an input terminal or an output of a symmetric DC / DC converter. A symmetrical DC / DC converter, wherein the symmetrical DC / DC converter is configured as a terminal, and configured by connecting one of the input / output terminals. 3. The symmetric DC / DC converter according to claim 1, wherein said pair of switch means comprises four switch sections, and said switch sections are capable of high-speed switching between open and short-circuit at appropriate intervals and a short-circuit. A symmetrical DC / DC converter comprising a mechanism for maintaining a state and a rectifying mechanism capable of flowing a current only in one direction. 4. The symmetric DC / DC converter according to claim 1, wherein said pair of switch means includes four switch units, and at least one of said switch units includes a rectifying mechanism using a synchronous rectification method. A symmetric DC / DC converter. 5. The symmetric DC / DC converter according to claim 1, wherein one of said pair of switch means is a first switch.
And a second switch unit, and the other of the pair of switch means includes a third and a fourth switch unit, and a terminal that commonly connects one of the input and output is an input / output common terminal. The first switch section between the input terminal and the inductor is short-circuited, and the second switch section between the connection section between the first switch section and the inductor and the input / output common section is opened. A connection portion between the third switch portion and the inductor and an input / output common portion in a state where the third switch portion between the output terminal and the inductor is rectified in a direction in which a current flows from the inductor to the output terminal. By setting the fourth switch section between the first and fourth switch sections to a state in which open and short circuits can be quickly switched at appropriate intervals, and controlling the open and short switch intervals of the first to fourth switch sections,
A symmetric DC / DC converter capable of boosting an input voltage to an arbitrary voltage and outputting the voltage. 6. The symmetric DC / DC converter according to claim 1, wherein one of said pair of switch means is a first switch means.
And a second switch section, the other of the pair of switch means including third and fourth switch sections, and opening and short-circuiting the first switch section between an input terminal and an inductor. The second switch section between the connection between the first switch section and the inductor and the input / output common section in a direction in which current flows from the input / output common section to the inductor so that high-speed switching can be performed at intervals. In a charged state, a third switch section between the output terminal and the inductor is short-circuited, and a fourth switch between the connection section between the third switch section and the inductor and the input / output common section. The input voltage is reduced to an arbitrary voltage by controlling the switching interval between the opening and the short-circuit of the first to fourth switch units which can switch between the open and the short-circuit. Symmetrical DC / DC converter, characterized in that it is Rukoto. 7. The symmetric DC / DC converter according to claim 1, wherein the voltage or the current of each of the two input / output terminals is measured, and energy is transferred by recognizing a state of the input / output terminal. The switch automatically determines the direction to be opened and switches between open and short circuits at appropriate intervals at high speed, maintains short circuits, and allows current to flow in only one direction. A symmetric DC / DC converter, comprising: a control device capable of controlling the switches, wherein the four switch units constitute the pair of switch means. 8. The symmetric DC / DC converter according to claim 1, wherein a voltage or a current of both of the two input / output terminals is measured to determine a state of the input / output terminal, and the input / output terminal is determined. The state of energy transfer is automatically determined by comprehensively examining the state information and information obtained from the outside, and the state in which opening and short-circuiting can be rapidly switched at appropriate intervals, the state in which short-circuiting is maintained, A control device capable of controlling the four switch units to an arbitrary state among states in which current can flow only in the direction;
A symmetrical DC / DC converter, wherein one switch unit constitutes the pair of switch means.