JP2957344B2 - Bidirectional 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 for converting a terminal voltage of a DC power supply. The present invention relates to a DC / DC converter capable of bidirectionally converting DC energy between a low voltage side terminal and a high voltage side terminal.

[0002] The present invention converts mechanical energy generated when braking an internal combustion engine into electrical energy and accumulates the same, and supplies the accumulated electric energy to an auxiliary accelerator when accelerating the internal combustion engine. Although it has been developed for use in a device that generates mechanical energy, the application is not limited to this device.

[0003] The present invention relates to International Publication WO 88/061.
7 (International Application No. PCT / JP / 000015). The present invention is a device suitable for mounting on a vehicle equipped with an auxiliary acceleration and auxiliary braking device which is sold on a trial basis by the present applicant under the name of HIMR.

[0004]

2. Description of the Related Art Conventionally, the current of a DC input terminal is intermittently switched by a chopper, stepped up or stepped down by a transformer, rectified, and supplied to a DC output terminal.
Although a DC converter is widely known, in a conventional device, an input terminal and an output terminal are fixed, and a bidirectional converter that can be used by exchanging an input terminal and an output terminal depending on an operation mode is not known.

In a large-scale process control system used in a thermal power plant or the like, a plurality of DC power supplies having different voltages may be used. Even if one of the plurality of DC power supplies fails, another DC power supply may be used. There is known a system in which DC / DC converters are coupled to each other so that a power supply current can be supplied from the DC / DC converter.
Two systems of DC converters are provided, and are configured to be switched and used depending on the direction of energy supply.

In an automobile equipped with the above-described electric braking and auxiliary acceleration device, a cage-type polyphase induction machine coupled to an internal combustion engine, DC power storage means, the cage-type polyphase induction machine and the DC power storage means are provided. In the acceleration mode, energy is extracted from the DC storage means, converted into polyphase alternating current by the inverter, and supplied to the cage-type polyphase induction machine in the acceleration mode, and the cage-type polyphase induction machine is used as an electric motor. In the deceleration mode, the squirrel-cage polyphase induction machine is used as a generator to convert the output polyphase alternating current of the squirrel-cage polyphase induction machine by an inverter and store it in a storage means. In such a device, the DC terminal voltage of the inverter is 200 to 3
It is 00 V, and a lead storage battery is connected in series as a power storage means to correspond to this terminal voltage.

[0007] However, the automobile equipped with this device also uses headlights, air conditioners and the like having a rated voltage of 24 V (or 12 V).
V) A standard battery is required. Therefore 300V
And a 24V battery.

[0008]

The high-voltage battery of the electric braking and auxiliary acceleration device has a large volume and a large weight, and it is very difficult to mount it on an automobile and perform appropriate maintenance. It was conceived to use extremely large capacitors instead of batteries.
This technology was filed at the same time as the present application.

When a high-voltage capacitor is used instead of a high-voltage battery, the battery can be made into one system. However, in a normal running state, it is necessary to charge the electric charge stored in the high-voltage capacitor to the low-voltage battery. It is. This includes DC ・ D
A C converter is available. But with this device, when the car is parked for a very long time,
Alternatively, when operating for the first time immediately after manufacturing, the high-voltage capacitor has little stored electric charge, so the high-voltage capacitor must be charged using the energy of the low-voltage battery. Although a DC / DC converter can be used in this case, the direction of energy transmission is opposite to that of the DC / DC converter described above.

For this purpose, it has been considered that two systems of DC / DC converters are provided for each direction of energy transmission and are used by switching according to the operation mode. It is very inconvenient to mount two DC converters. Therefore, DC / DC that can transmit energy bidirectionally
I needed a converter.

That is, according to the present invention, in a DC / DC converter having a low voltage side terminal and a high voltage side terminal, energy is transmitted from the low voltage side terminal to the high voltage side terminal and from the high voltage side terminal to the low voltage side terminal depending on the operation mode. Possible bidirectional D
It is an object to provide a C / DC converter.

[0012]

According to the present invention, there is provided a low voltage side terminal, a high voltage side terminal, a transformer including a low voltage side winding and a high voltage side winding, and a transformer between the low voltage side terminal and the low voltage side winding. A low-side switching element inserted into the high-side terminal and the high-side winding; a high-side switching element inserted between the high-side winding; a low-side rectifying element connected in parallel to the low-side switching element; A high-side rectifying element connected in parallel to the high-side switching element; and a control circuit for controlling the low-side switching element and the high-side switching element.
The pair of the pressure side rectifying elements connected in parallel is the low voltage side winding.
High-side switching connected to both ends of the line
The element and the high voltage side rectifying element
The control circuit is connected to both ends of the high-voltage side winding , and in a low-voltage / high-voltage conversion mode, the control circuit supplies an open / close control signal to the low-voltage switching element to maintain the high-side switching element in an open state; the low-pressure conversion mode, and selecting means for selecting a control means for maintaining the low voltage side switching element provides a switching control signal to the high voltage side switching element in an open state, one of the two control modes, the low-pressure High pressure conversion mode or
Is the low pressure side or high pressure side in the high pressure / low pressure conversion mode.
Control means for alternately opening and closing the two sets of switching elements
It is characterized by including a step .

A low voltage side voltage detection circuit for detecting a terminal voltage of the low voltage side terminal; and a high voltage side voltage detection circuit for detecting a terminal voltage of the high voltage side terminal. A low-voltage side detecting means for receiving the respective detection outputs of the detection circuit, automatically comparing the two detection outputs with respective reference values, and automatically controlling the selection means; A high-side current detection circuit for detecting a current of the high-side winding.

The control circuit includes means for receiving the detection outputs of the two current detection circuits and transmitting an abnormality alarm output when the two detection outputs are not within the respective allowable ranges of the two control modes. Is desirable.

[0015]

In the low pressure / high pressure conversion mode, an open / close control signal is supplied to the low voltage side switching element to maintain the high voltage side switching element in an open state. In this case, the applied voltage of the low voltage side rectifying element connected in parallel with the low voltage side switching element is in the opposite direction, and does not operate. The applied voltage of the high-side rectifier connected in parallel to the high-side switching element maintained in the open state is in the forward direction, and acts as a rectifier.

In the high-to-low pressure conversion mode, an open / close control signal is supplied to the high-side switching element to maintain the low-side switching element in an open state. In this case, the applied voltage of the high-voltage side rectifying element connected in parallel with the high-voltage side switching element is in the opposite direction, and does not operate. The applied voltage of the low-voltage side rectifier connected in parallel with the low-voltage side switching element maintained in the open state is forward and acts as a rectifier.

Generally, most of the volume and weight of a DC / DC converter is a transformer, and a switching element, a rectifying element, or a control circuit formed of a semiconductor element is extremely small and light in weight as compared with a transformer. In the present invention, the switching element and the rectifying element are provided for two systems. However, since only one transformer is required, the volume and the weight are almost the same as those of one DC / DC converter.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the embodiment of the present invention.

In the embodiment of the present invention, the low voltage side terminals 1a and 1
b, the high voltage side terminals 1c and 1d, the transformer 5 including the low voltage side winding 2 and the high voltage side winding 3, and the low voltage side switching inserted between the low voltage side terminals 1a and 1b and the low voltage side winding 2. Elements Ta and Tb, high-side switching elements Tc and Td inserted between high-side terminals 1c and 1d and high-side winding 3, and low-side switching element T
a and Tb connected in parallel to the low-voltage rectifiers Da and Db, respectively, and the high-voltage rectifiers Dc and Dd connected in parallel to the high-voltage switching elements Tc and Td.
And a control circuit 4 for controlling the low-voltage switching elements Ta and Tb and the high-voltage switching elements Tc and Td. The control circuit 4 includes an open / close control signal to the low-voltage switching elements Ta and Tb in the low-voltage high-voltage conversion mode. And a control means for maintaining the high-voltage switching elements Tc and Td in an open state, and in the high-voltage / low-voltage conversion mode, providing an open / close control signal to the high-voltage switching elements Tc and Td to maintain the low-voltage switching elements Ta and Tb in an open state. And control means for selecting one of the two control modes.

A low voltage side voltage detecting circuit V1 for detecting terminal voltages of the low voltage side terminals 1a and 1b,
a high-side voltage detection circuit V2 for detecting the terminal voltages of terminals c and 1d. Further, the control circuit 4 takes in the respective detection outputs of the two voltage detection circuits V1 and V2 at startup, and Means for automatically controlling the selection means by comparing the output with respective reference values, detecting a current in the low voltage side winding 2 and detecting a current in the high voltage side winding 3 And the control circuit 4 captures the detection outputs of the two current detection circuits I1 and I2, and the two detection outputs are not within the respective allowable ranges of the two control modes. Means for sending an abnormal alarm output at times.

Next, the operation of the embodiment of the present invention thus configured will be described.

In the low-voltage / high-voltage conversion mode, the control circuit 4 supplies an open / close control signal to the low-voltage switching elements Ta and Tb to open the high-voltage switching elements Tc and Td. At this time, the low-voltage side rectifying elements Da and Db connected in parallel with the low-voltage side switching elements Ta and Tb do not act because the applied voltage is in the reverse direction, and are kept in the open state. The high-voltage rectifiers Dc and Dd connected in parallel with Tc and Td operate as rectifiers because the applied voltage is in the forward direction.

In the high-to-low voltage conversion mode, the control circuit 4 supplies an open / close control signal to the high-side switching elements Tc and Td to open the low-side switching elements Ta and Tb. At this time, the voltages applied to the high-side rectifiers Dc and Dd connected in parallel with the high-side switching elements Tc and Td have no effect because they are in opposite directions. The voltages applied to the low-voltage rectifiers Dc and Dd connected in parallel with the low-voltage switching elements Ta and Tb maintained in the open state operate as rectifiers in the forward direction.

FIG. 2 is a timing chart showing the switching operation of the switching element in the embodiment of the present invention. FIG.
The voltage conversion operation by switching the switching element will be described in detail with reference to FIG.

In the low-voltage / high-voltage conversion mode, the control circuit 4 alternately opens and closes the low-voltage switching elements Ta and Tb, and keeps the high-voltage switching elements Tc and Td open. As a result, an alternating current flows through the low-voltage winding 2 to excite the low-voltage winding 2 and induce a high-voltage current in the high-voltage winding 3. At this time, the high-voltage side switching element T
Since c and Td are in the open state, the generated high-voltage current is rectified through the high-side rectifying element Dc or Dd and is converted to a high voltage between the high-side terminals 1c and 1d.
2 appears.

Next, the high-to-low pressure conversion mode will be described. In this case, the control circuit 4 continuously opens the low-voltage switching elements Ta and Tb and alternately opens the high-voltage switching elements Tc and Td. The alternating current generated thereby excites the high voltage side winding 3, and the excitation of the high voltage side winding 3 induces a low voltage current in the low voltage side winding 2. At this time, since the low-voltage switching elements Ta and Tb are continuously open, the generated low-voltage current is rectified through the low-voltage rectification element Da or Db and converted to low voltage by the low-voltage terminals 1a and 1b. The voltage V1 appears.

The terminal 1b serving as a common potential on the low voltage side and the terminal 1d serving as a common potential on the high voltage side are completely separated by the transformer 5.

FIG. 3 is a diagram showing an example in which the bidirectional DC / DC converter according to the present invention is applied, and shows an example in which the bidirectional DC / DC converter is used for braking and an auxiliary power unit of an internal combustion engine. In this example, a squirrel-cage polyphase induction machine 12 whose rotor is directly connected to an internal combustion engine 11, a secondary battery circuit 13 and a capacitance circuit 14, and a secondary battery circuit 13 and a capacitance circuit 14
Is converted to an AC voltage having a frequency suitable for inducing a rotating magnetic field having a rotation speed lower than the shaft rotation speed of the cage-type polyphase induction machine 12, and this is supplied to the cage-type polyphase induction machine 12, and An inverter circuit 15 for converting AC power from the cage-type polyphase induction machine 12 into DC power; an inverter control circuit 16 for generating a control signal for setting a frequency of an AC side voltage of the inverter circuit 15; A rotation sensor 17 that detects the rotation speed and sends it to an inverter control circuit 16 to send information about the state of charge of the secondary battery circuit 13 and the capacitance circuit 14. A bidirectional DC / DC converter 10 is mounted in order to connect between the circuit and the capacitance circuit 10. In this case, 24 V or 12 V is normally supplied from the secondary battery circuit 13 to the vehicle load, and low voltage to high voltage conversion is performed when charging the capacitance circuit. Is operated when the high voltage from the inverter circuit 15 is converted to a low voltage and the secondary battery circuit 13 is charged.

FIG. 4 shows another application example, in which a large-scale process control device 20 used in a thermal power plant or the like is used.
In the case where a plurality of DC power supplies 21, 22, 23 having different voltages are used, even if any of the plurality of power supplies 21, 22, 23 fails, a switch of the failed power supply is used. With S1, S2, or S3 open, the bidirectional DC / DC converter 10 can convert a voltage from another power supply to a predetermined voltage, supply the voltage, and continue to operate.

[0030]

As described above, according to the present invention, when there are two energy transmission directions, the energy is converted from the low pressure side to the high pressure side or from the high pressure side to the low pressure side according to the transmission direction. There is an effect that can be supplied.

The present invention can be widely applied not only to a vehicle braking or auxiliary acceleration device, but also to a thermal power plant or a manufacturing factory for performing process control.

Since most of the volume and weight of the DC / DC converter is reduced by the transformer, the bidirectional DC / DC converter of the present invention is used.
The DC converter consists of two DC-DC converters in the opposite direction.
It can be configured to be significantly smaller than one that is switched and connected using a stand.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a timing chart showing an opening / closing operation of a switching element in the embodiment of the present invention.

FIG. 3 is a diagram showing an example in which the device according to the embodiment of the present invention is applied to a braking and auxiliary acceleration device of a vehicle.

FIG. 4 is a diagram showing an example in which the apparatus according to the embodiment of the present invention is applied to process control of a thermal power plant.

[Explanation of symbols]

 1a, 1b Low voltage side terminal 1c, 1d High voltage side terminal 2 Low voltage side winding 3 High voltage side winding 4 Control circuit 5 Transformer 10 DC / DC converter 11 Internal combustion engine 12 Cage-shaped polyphase induction machine 13 Secondary battery circuit 14 Electrostatic Capacitance circuit 15 Inverter circuit 16 Inverter control circuit 20 Process control device 21 to 23 DC power supply Da, Db Low-side rectifying element Dc, Dd High-side rectifying element Ta, Tb Low-side switching element Tc, Td High-side switching element V1 Low-side voltage Detection circuit V2 High voltage side voltage detection circuit I1 Low voltage side current detection circuit I2 High voltage side current detection circuit S1, S2, S3 Switch

Claims (3)

(57) [Claims] 1. A low voltage side terminal, a high voltage side terminal, and a low voltage side winding.
A transformer including a wire and a high voltage side winding, and the low voltage side terminal
Low-voltage switch inserted between the low-voltage winding and the low-voltage winding
Between the high-voltage side terminal and the high-voltage side winding.
High-side switching element and the low-side switch
A low-voltage rectifier element connected in parallel to the
High-side rectifier connected in parallel with the high-side switching element
And the low voltage side switching element and the high voltage side switch.
And a control circuit for controlling the switching element,The low voltage side switching element and the low voltage side rectifying element are
Are connected in parallel at both ends of the low-voltage side winding.
Connected The high-side switching element and the high-side rectifying element are
Are connected in parallel to both ends of the high-voltage side winding.
Connected  In the low-voltage / high-voltage conversion mode, the control circuit includes the low-voltage side switching element.
To open / close the high-voltage side switching element.
Control means for maintaining the high-side switching element in a high-pressure / low-voltage conversion mode.
To the low-voltage side switching element.
Control means for maintaining the release state, and selection means for selecting one of the two control modes
Be preparede, In the low pressure / high pressure conversion mode or the high pressure / low pressure conversion mode
Said two sets of switching elements on the low pressure side or the high pressure side.
Including control means to open and close the child alternately Characterized by
Bidirectional DC / DC converter. 2. A low voltage side voltage detection circuit for detecting a terminal voltage of the low voltage side terminal, and a high voltage side voltage detection circuit for detecting a terminal voltage of the high voltage side terminal, wherein the control circuit is configured to start the second voltage when starting up. 2. The bidirectional DC / DC converter according to claim 1, further comprising means for taking in respective detection outputs of the two voltage detection circuits, comparing the two detection outputs with respective reference values, and automatically controlling the selection means. 3. A low voltage side current detecting circuit for detecting a current of the low voltage side winding, and a high voltage side current detecting circuit for detecting a current of the high voltage side winding. 2. The bidirectional DC / DC converter according to claim 1, further comprising means for receiving a detection output of the detection circuit and transmitting an abnormality alarm output when the two detection outputs are not within the respective allowable ranges of the two control modes.