JP3484636B2 - Symmetric DC / DC converter - Google Patents

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 that boosts or lowers a voltage to transfer electrical energy, and more particularly to a symmetrical 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 energy stored. When an electric double layer capacitor is used, it is necessary to boost or lower the voltage to transfer energy when charging or discharging.

When a motor of an electric vehicle or the like is used as a load that consumes the electric power of the electric double layer capacitor, the energy efficiency of the entire system is improved by recovering the energy when the motor reversely generates power during braking. Greatly increased.

Therefore, in order to raise or lower the voltage, DC /
It is important for the function of the DC converter to be able to transfer energy from one side to the other side. A method of preparing a DC / DC converter for each direction and switching with a switch can be considered, but this is not practical because the entire device becomes large. Therefore, DC / D that functions even if the input and output are switched in one circuit
The C converter becomes 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 an example of the configuration 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 left open and the switch circuit 27 is set. It is controlled by PWM and operates as a forward converter circuit.

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

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

Referring to FIG. 13, a bidirectional DC / DC converter according to the conventional technique 2 is provided between a DC power supply 33 and a load 37 including a capacitor 35. Prior art 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, an inductance 23, and a controller (not shown). The first series circuit 43 includes a first FET 39 and a second FET that are connected in parallel to a DC power supply.
And 41. The second series circuit 49 also includes a third FET 45 and a fourth FET 47 that are connected in parallel to the load. The inductance 23 is composed of the first FET 39 and the second FE.
It is provided between the connection point with T41 and the connection point with the third FET 45 and the fourth FET 47. In addition, the controller
The energy of the DC power supply 33 is supplied to the load 37,
In addition, the first FET 39, the second FET 41, the third FET 45, and the fourth F so as to regenerate the energy stored in the capacitor 35 to the DC power supply 33.
This is a configuration for controlling each gate of the ET 47.

[0010]

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

In addition, when using an electric storage device in which the voltage of the electric double layer fluctuates like a capacitor, or when driving and regenerating with 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 a system is constructed by combining a plurality of energy storage devices, generators and loads, it is necessary to set the step-up ratio and step-down ratio appropriately.
A conventional bidirectional converter could not handle this.

Therefore, a technical object of the present invention is to provide a symmetrical DC / DC converter which operates in a direction corresponding to energy transfer and a step-up ratio or step-down ratio corresponding to an input / output voltage ratio. .

[0014]

According to the present invention, a pair of switch means is connected to each terminal of one inductor in a symmetrical manner with respect to the inductor.
A C converter that operates as a step-up converter and a step-down converter by using one of the pair of switch means as an input and the other as an output, and uses the input as an output and the output as an input. Can operate as an input or output
It is intended to provide a symmetrical DC / DC converter characterized in that an electric double layer capacitor is connected to one side or both sides .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

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

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

FIG. 2 is a circuit diagram of a symmetrical DC / DC converter according to the second embodiment of the present invention. FIG. 3 is FIG.
FIG. 3 is a configuration diagram of the symmetric DC / DC converter when the boosting operation is performed with the third and fourth terminals as inputs. 4 is shown in FIG.
FIG. 3 is a configuration diagram when the step-down operation is performed with the third and fourth terminals of the symmetrical DC / DC converter of FIG.

Referring to FIG. 2, a symmetrical DC / DC converter 55 according to a second embodiment of the present invention has switch parts 57, 59 and 61, 63 at both ends of the inductor 23.
And one end of each of the switch parts 57, 59 and 61, 6
The other end of 3 is connected to terminals 65, 67, 69 and 71, respectively, and capacitors 73 and 73 are inserted between the switch portions 57, 59 and 61 and 63, respectively, to connect terminals 67 and 71. Is connected to form four terminals.

Table 1 below shows the first and second terminals 6
5 and 67 are input and the 3rd and 4th terminals 69 and 71 are output, and 1st and 2nd terminals 65 and 67 are output and 3rd
And the operation when the fourth terminals 69 and 71 are input is separately shown.

[0021]

[Table 1]

In Table 1 above, the switch parts 57, 5
The operation in each case of 9, 61, and 63 is shown, and in the above Table 1, “ON” is in a short-circuit state, “OFF” is in an open state,
“SW” indicates a state in which ON-OFF is intermittently performed and controlled so as to have an appropriate step-up ratio or step-down ratio by PWM control or the like, 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 by using 5, 67 as an input and the third and fourth terminals 69, 71 as an output.

The switch unit 57 is "ON" so that it is short-circuited, the switch unit 59 is "OFF" because it is open, and the switch unit 61 is "D" so that the diode 75 and the switch unit 63 that perform the rectifying operation are "SW". Therefore, the switch circuit 77 is provided, and control is performed so as to obtain an appropriate boost ratio.

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.
With 1 as the output, the symmetrical 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 performs control so as to have an appropriate step-down ratio. Further, since the switch unit 59 is “D”, it functions as the diode 75 for performing the rectifying operation, the switch unit 61 is “ON”, and thus the short circuit occurs, and the switch unit 63 is “OFF”.
Therefore, it will be open.

The first and second terminals 65 and 67 are output, and the third terminal
Also, when the fourth terminals 69 and 71 are input, the same operation can be realized by simply replacing the switch sections 57 and 59 and 61 and 63 with each other.

FIG. 5 is a circuit diagram showing a symmetrical DC / DC converter according to a third embodiment of the present invention. Referring to FIG. 5, a symmetrical shape 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.
The switch circuit 77 and the rectifier 75 are connected in parallel to each of 9, 61, and 63.

Table 2 below shows the inputs of the first and second terminals 65 and 67 in the symmetric DC / DC converter of FIG.
When the third and fourth terminals 69 and 71 are output,
And outputs the second terminals 65 and 67, and the third and fourth terminals 6
In addition to the case of inputting 9,71, and further,
In each case, the operation of the switch unit is collectively shown according to the case of step-up or step-down.

[0030]

[Table 2]

In Table 2 above, when the switch circuit 77 is turned off "OFF", the diode 75 is connected in parallel, so the operation of the switch section is the rectification operation "D".
Becomes Therefore, the opening operation "OF
All the "F" parts are replaced with the rectifying operation "D" in Table 2 above.

However, since a voltage is not applied in the forward direction to the diode of the switch section at the place where the opening operation is changed to the rectifying operation, it becomes equivalent to the opening operation.
The same operation as shown in Table 1 above can be performed.

Therefore, in the symmetrical 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 symmetrical DC / DC converter according to a fourth embodiment of the present invention. Referring to FIG. 6, the symmetrical shape D according to the fourth embodiment of the present invention.
In the C / DC converter, 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 that of the body diode 83 is connected in parallel to the body diode 83 of the FET 81 in the same direction, the body diode 83 is formed. It can operate as a symmetric DC / DC converter without affecting.

FIG. 7 is a circuit diagram showing a symmetrical DC / DC converter according to a fifth embodiment of the present invention. Referring to FIG. 7, a symmetrical shape D according to a fifth embodiment of the present invention.
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 set to the FET 8 so that the output of the operational amplifier 89 is not saturated 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 energy transfer can be freely selected, and the step-up and step-down ratios can be freely changed to operate. A symmetrical DC / DC converter can be provided.

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

Referring to FIG. 8, the symmetrical DC / DC converter 91 according to the sixth embodiment of the present invention has the same energy transfer device as the symmetrical DC / DC converter according to the second embodiment. It is the same. An energy storage device that transfers energy, a power generation device, an electric double layer capacitor 17 as an example of a load, a solar cell 93, and a light emitting element 95 are connected. The controller 97 includes a voltage monitor 99,
101, voltage information of each terminal, current sensor 103, 1
Current information of each terminal can be obtained from 05. Further, the control device has a function of judging the situation from the information, and it is possible to switch the switch parts 57, 59, 61, 63 at a high speed switching between open and short states, short-circuited state, open state, and one-way current flow. It is connected so that it can be controlled to any of the commutation states.

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

When the direction of energy transfer and the boosting / decreasing pressure are determined, the switch parts 57, 59, 61, 63 are set to operate as shown in Table 3 below, and the switch parts which operate as SW are operated. The open and short circuit intervals are set to appropriate values according to the ratio of input / output voltage (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), and how is the operation performed? It is determined whether or not the operation should be performed, and the operation is normally repeated unless there is an instruction to end the operation.

[0043]

[Table 3]

In the case of the sixth embodiment of the present invention, not only the generated power of the solar cell 93 is consumed by the light emitting element 95, but also the surplus power is charged in the electric double layer capacitor 17. The control device 75 determines to operate to charge the electric double layer capacitor 17 while the solar cell 93 is generating power until the light emitting element 95 can sufficiently emit light. At this time, the electric double layer capacitor 17
Whatever the energy state or voltage value of
The control device 97 determines the input and output voltages, determines the step-up and step-down, and charges the electric double layer capacitor 17. Furthermore, when it is desired to cause the light emitting element 95 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 of the electric double layer capacitor 17 is higher or lower than the voltage required for light emission of the light emitting element 95. By adjusting and discharging the light emitting element 95, the light emitting element 95 can emit light with a required brightness.

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

Referring to FIG. 10, in the symmetrical DC / DC converter according to the seventh embodiment of the present invention, the structure of the device for transferring energy is the same as that of the symmetrical DC / DC converter according to the third embodiment. Is. An energy storage device that transfers energy, a power generation device, an electric double layer capacitor 17 as an example of a load, and a motor 19 are connected. The control device 97 controls the voltage information of each terminal from the voltage monitors 99 and 101, the current sensor 103, The current information of each terminal can be obtained from 105.

The motor 19 required by the user
It is possible to obtain the torque information of the above through the torque setting device 107. Further, the control device 97 has a function of judging the situation from the information, and the respective switch circuits 77
Is connected so that it can be controlled to be in a state in which it can switch between open and short at high speed, a short-circuit state, or an open state.

Referring to FIG. 11, in the symmetrical 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 information on the voltage from the voltage monitors 99 and 101, the information on the current 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. (Steps SB1, SB2, SB3), which input and output terminals are to be used (step SB4), and whether to operate as a step-up converter or a step-down converter (step SB5).

When the direction of energy transfer and the boosting / decreasing pressure are determined, the state of the switch circuit 77 is set so that the switch portions 57, 59, 61 and 63 operate as shown in Table 4 below, and the SW operation is performed. The interval of opening and short-circuiting of the switch circuit of the switch section that is operating is set to an appropriate value according to the ratio of the input / output voltage (step SB6). After energy transfer is performed (step SB7), the control device 97 again determines the voltage information from the voltage monitors 99 and 101 and the current information from the current sensor, and determines how to operate (step). SB8).

[0050]

[Table 4]

In the case of the seventh embodiment of the present invention, the signal from the outside is used as the torque of the motor 19 desired by the user, and the motor 1 at which the desired torque is actually operating.
When the torque is less than 9, for example, when it is desired to stop the rotation while the motor 19 is rotating, the motor 19 acts as a power generator. At this time, regardless of the energy state of the electric double layer capacitor 17, that is, the voltage value, or the voltage value output by the motor 19, the control device 97 determines the input and output voltages and boosts the voltage. Then, the step-down voltage is determined, and the electric double layer capacitor 17 is charged. When the desired torque is higher than the torque of the motor 19 which is actually operating, for example, when a certain amount of rotation is desired while the motor 19 is stopped, 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 appropriately.

[0052]

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

[Brief description of drawings]

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

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

FIG. 3 is a configuration diagram of the symmetrical DC / DC converter of FIG. 2 when the third and fourth terminals are input and a boosting operation is performed.

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

FIG. 5 shows a symmetrical DC / according to a third embodiment of the invention.
It is a circuit diagram which shows a DC converter.

FIG. 6 is a symmetrical DC / according to a fourth embodiment of the invention.
It is a circuit diagram which shows a DC converter.

FIG. 7 shows a symmetrical DC / according to a fifth embodiment of the invention.
It is a circuit diagram which shows a DC converter.

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

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

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

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

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

FIG. 13 is a circuit diagram showing a configuration of a bidirectional DC / DC converter according to Related Art 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 1st FET 41 Second FET 43 First Series Circuit 45 3rd FET 47 4th FET 49 Second series circuit 51 Symmetric DC / DC Converter 53 Switch means 55 Symmetric DC / DC Converter 57, 59, 61, 63 Switch section 65, 67, 69, 71 terminals 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 cells 95 Light emitting device 97 Control device 99, 101 voltage monitor 103,105 Current sensor 107 Torque setting device

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP 2000-60116 (JP, A) JP 2000-23453 (JP, A) JP 10-243642 (JP, A) JP 2001-268900 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 3/155

Claims (8)

(57) [Claims] 1. A DC / DC 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, and one of the pair of switch means is Operates as a step-up converter and a step-down converter with the input and the other as output,
And, an output of the input, can also operate as a boost converter and buck converter as inputs the output, input
Electric double layer key for either or both power and output
Symmetrical DC / DC characterized by connecting a capacitor
converter. 2. The symmetrical DC / DC converter according to claim 1, wherein an intermediate terminal of two switch parts connected in series with one terminal of the inductor is connected to the two connected in series. A capacitor was connected in parallel to both terminals of each switch section to configure the terminals as an input terminal or an output terminal of a symmetrical DC / DC converter, and similarly connected in series with another terminal of the inductor. An intermediate terminal of two switch parts is connected, and a capacitor is connected in parallel to both terminals of the two switch parts connected in series, and the both terminals are input terminals or outputs of a symmetrical DC / DC converter. A symmetric DC / DC converter characterized in that it is configured as a terminal, and one terminal of each of the input / output terminals is connected. 3. The symmetrical DC / DC converter according to claim 1, wherein the pair of switch means includes four switch parts, and the switch parts are short-circuited with a mechanism capable of high-speed switching between open and short at appropriate intervals. A symmetric DC / DC converter comprising a mechanism for maintaining a state and a rectifying mechanism capable of passing a current in only one direction. 4. The symmetrical DC / DC converter according to claim 1, wherein the pair of switch means comprises four switch parts, and at least one of the switch parts comprises a rectifying mechanism using a synchronous rectification method. A symmetric DC / DC converter characterized in that 5. The symmetrical DC / DC converter according to claim 1, wherein one of the pair of switch means is the first.
And a second switch section, the other of the pair of switch means has a third and a fourth switch section, and a terminal commonly connecting one of the input and the output is a common input and output terminal, The first switch section between the input terminal and the inductor is short-circuited, and the second switch section between the input / output common section and the connection section between the first switch section and the inductor is open. In a state where the third switch section between the output terminal and the inductor is rectified in a direction in which a current flows from the inductor to the output terminal, a connection section between the third switch section and the inductor and an input / output common section are provided. By making the fourth switch section between and between the first and fourth switch sections open and short-circuited at a high-speed switchable state at a suitable interval, and controlling the open and short-circuit switching intervals.
A symmetric DC / DC converter capable of boosting an input voltage to an arbitrary voltage and outputting the boosted voltage. 6. The symmetrical DC / DC converter according to claim 1, wherein one of said pair of switch means is first.
And a second switch part, and the other of the pair of switch means is provided with a third and a fourth switch part for opening and shorting the first switch part between the input terminal and the inductor. The second switch section between the connection section between the first switch section and the inductor and the input / output common section is set in a direction in which a 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 and output by controlling the switching interval of the opening and the shorting of the first to fourth switch portions that can switch the opening and the short circuit by opening the portion. Symmetrical DC / DC converter, characterized in that it is Rukoto. 7. The symmetrical DC / DC converter according to claim 1, wherein voltage or current is measured at both of the two input / output terminals, and energy is transferred by recognizing the state of the input / output terminals. 4 switches in any of the following states: automatically determine which direction to open, and can switch between open and short at high speed with appropriate intervals, maintain a short, and allow current to flow in only one direction. A symmetric DC / DC converter, comprising a control device capable of controlling the parts, wherein the four switch parts constitute the pair of switch means. 8. The symmetrical DC / DC converter according to claim 1, wherein the voltage or current of both of the two input / output terminals is measured, the state of the input / output terminal is determined, and the input / output terminal is determined. The information of the state and the information obtained from the outside are comprehensively examined, and the direction of energy transfer is automatically determined, and the state where the open circuit and the short circuit can be switched at high speed at an appropriate interval, the state where the short circuit is maintained, A control device capable of controlling the four switch parts in any of the states in which the current can flow in only one direction;
A symmetric DC / DC converter, wherein one switch section constitutes the pair of switch means.