JP5765075B2 - Power conversion device and charging device - Google Patents

Description

  The present invention relates to a power conversion device that converts DC power and a charging device that includes the device.

  As is well known, power converters that convert DC power are generally called DC / DC converters, and are roughly classified into non-insulated types and insulated types. The insulated DC / DC converter includes, for example, a transformer (transformer), a first converter connected to the primary side of the transformer to convert DC power into AC power, and an AC power connected to the secondary side of the transformer. And a second converter that converts DC to DC power.

  In recent years, bidirectional insulated DC / DC converters that can transmit DC power from the primary side to the secondary side of the transformer as well as direct current power from the secondary side to the primary side of the transformer have been developed. . In this bidirectional insulated DC / DC converter, switching circuits (bridge circuits) are provided on both the primary side and the secondary side of the transformer, and the timing for driving the switching circuit provided on the primary side of the transformer; By changing the timing of driving the switching circuit provided on the secondary side of the transformer, DC power can be transmitted from the primary side to the secondary side, or DC power can be transmitted from the secondary side to the primary side. It is.

  By using the above-described bidirectional insulation type DC / DC converter, for example, a secondary battery such as a lithium ion battery provided on the secondary side is charged as necessary, and the DC power charged in the secondary battery It is possible to realize a charging device that can be taken out to the primary side as needed. For details of the bidirectional insulated DC / DC converter, see, for example, Non-Patent Document 1 below.

Shigenori Inoue and one other, “Basic Experiments of Energy Storage System Using Bidirectional Insulated DC / DC Converter”, Proceedings of 2006 Annual Conference of the Institute of Electrical Engineers of Japan, Vol. 2006, No. 4, p. 49

  By the way, in the bidirectional insulated DC / DC converter disclosed in the above-mentioned Patent Document 1, the output voltage on the secondary side of the transformer is almost determined by the winding ratio between the primary side winding and the secondary side winding. . For this reason, a charging device provided with such a bidirectional insulation type DC / DC converter has a problem that a voltage range in which charging can be performed efficiently is narrow. Here, if the voltage of the secondary battery to be charged is constant, the secondary battery can be efficiently charged by designing a bidirectional insulated DC / DC converter according to the characteristics of the secondary battery. . However, when the output voltage of the secondary battery to be charged is in the range of several tens to several hundreds V, there is a problem that it is difficult to efficiently charge all the secondary batteries.

  The present invention has been made in view of the above circumstances, and a power conversion device whose output voltage is variable over a wide voltage range, and charging efficiently over a wide voltage range by including the device. It is an object of the present invention to provide a charging device capable of performing the above.

In order to solve the above problems, a power converter of the present invention includes a high-frequency transformer (23) and a first power conversion circuit (21) provided on the primary side of the high-frequency transformer for converting DC power and AC power. And a second power conversion circuit (25) that is provided on the secondary side of the high-frequency transformer and converts DC power and AC power, and a power converter (13) that converts DC power, At least one of the first and second power conversion circuits is connected to one end (P1) of a winding included in the high-frequency transformer, and a first switching leg (L11) formed by connecting switching elements (31a, 31b) in series. A second switching leg (L12) connected to the other end (P2) of the winding and connected in series with switching elements (31c, 31d), and between the one end and the other end of the winding. Is connected to the point (P3) is characterized in that it comprises a switching element (31e, 32f) at least one of the third switching leg (L13) and formed by serially connected.
Moreover, the power converter device of this invention is provided with the switch (24) which makes a short circuit state or an open state between the said midpoint and a said 3rd switching leg, It is characterized by the above-mentioned.
In the power converter of the present invention, the switch is a bidirectional switch, a relay switch, or a contactor.
Further, the power conversion device of the present invention is configured such that the switching provided in the first and second switching legs when the switch is controlled to open the middle point and the third switching leg. When the element is controlled and the switch is controlled to short-circuit between the midpoint and the third switching leg, the switching element provided in the first and third switching legs is controlled. It is characterized by comprising a control device (14) for performing.
The charging device of the present invention is a charging device (1) for charging a secondary battery (B) using AC power supplied from an AC power source (PS), wherein the AC power supplied from the AC power source is converted to DC power. And a converter (11) for converting to DC power and the power converter for converting DC power converted by the converter.
Moreover, the charging device of the present invention is characterized in that the control device controls the converter, the first and second power conversion circuits, and the switch according to characteristics of the secondary battery.

  According to the present invention, at least one of the first and second power conversion circuits provided on the primary side and the secondary side of the high-frequency transformer, respectively, a first switching leg connected to one end of the winding provided in the high-frequency transformer; Since the second switching leg connected to the other end of the winding and at least one third switching leg connected to the midpoint of the winding are provided, the output voltage can be varied over a wide voltage range. There is an effect that can be. Thereby, in a charging device, there exists an effect that it can charge efficiently over a wide voltage range.

It is a circuit diagram which shows the principal part structure of the charging device by one Embodiment of this invention. It is a circuit diagram which shows the example of the switch provided in the charging device by one Embodiment of this invention.

  Hereinafter, a power conversion device and a charging device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a main configuration of a charging device according to an embodiment of the present invention. As shown in FIG. 1, the charging device 1 of this embodiment includes a converter 11, a capacitor 12, a bidirectional DC / DC converter 13 (power conversion device), and a control device 14, and is supplied from an AC power supply PS. DC power for charging is generated from AC power (for example, three-phase AC power having a voltage of 200V).

  The DC power generated by the charging device 1 is output to the outside from the output terminals T1 and T2 of the bidirectional DC / DC converter 13, for example, a secondary battery such as a lithium ion secondary battery connected between the output terminals T1 and T2. Used to charge battery B. It is assumed that the secondary battery B connected between the output terminals T1 and T2 can take an output voltage in the range of several tens to several hundreds of volts. Here, the charging device 1 of the present embodiment can not only charge the secondary battery B connected to the output terminals T1 and T2, but also extract DC power charged in the secondary battery B. Then, in order to simplify the description, a case will be described in which the secondary battery B is charged mainly using AC power supplied from the AC power source PS.

  The converter 11 includes an AC reactor 11a and a PWM converter 11b, and converts the three-phase AC power supplied from the AC power PS into DC power. The AC reactor 11a is provided at the input end of the PWM converter 11b (between the AC power supply PS and the PWM converter 11b), and removes harmonic noise superimposed on the three-phase AC power supply supplied from the AC power supply PS. To do.

  The PWM converter 11b includes, for example, a plurality of diodes (for example, six diodes) constituting a three-phase full-wave rectifier circuit, and switching elements such as transistors connected in parallel to each of these diodes. Under the control of 14, the three-phase AC power supplied from the AC power source PS is rectified. The control device 14 performs PWM (Pulse Width Modulation) control of the switching element provided in the PWM converter 11b, thereby performing output voltage control and power factor compensation. The capacitor 12 is provided between the output terminals of the converter 11 (between the input terminals of the bidirectional DC / DC converter 13), and smoothes the power rectified by the converter 11 and converts it into DC power.

  The bidirectional DC / DC converter 13 includes a power conversion circuit 21 (first power conversion circuit), a reactor 22, a high frequency transformer 23, a switch 24, a power conversion circuit 25 (second power conversion circuit), and a capacitor 26. The DC power is converted under the control of the control device 14. Specifically, the DC power converted by the converter 11 is converted and output from the output terminals T1 and T2. Note that the DC power supplied from the secondary battery B connected to the output terminals T1 and T2 may be converted and output to the converter 11.

  The power conversion circuit 21 includes three switching legs L11 to L13 (first to third switching legs) in which switching elements are connected in series, and is converted by the converter 11 under the control of the control device 14. DC power is converted into AC power and output to the reactor 22 side. The power conversion circuit 21 can also convert AC power input from the reactor 22 side into DC power and output it to the converter 11.

  The switching leg L11 includes transistors 31a and 31b (switching elements) connected in series, a diode 32a and a capacitor 33a connected in parallel to the transistor 31a, and a diode 32b and a capacitor 33b connected in parallel to the transistor 31b. The switching leg L12 includes transistors 31c and 31d (switching elements) connected in series, a diode 32c and a capacitor 33c connected in parallel to the transistor 31c, and a diode 32d and a capacitor 33d connected in parallel to the transistor 31d. Similarly, the switching leg L13 includes transistors 31e and 31f (switching elements) connected in series, a diode 32e and a capacitor 33e connected in parallel to the transistor 31e, and a diode 32f and a capacitor 33f connected in parallel to the transistor 31f. Prepare.

  The above transistors 31 a to 31 f are insulated gate bipolar transistors, and the on state and the off state are controlled by the control device 14. As the transistors 31a to 31f, normal bipolar transistors can be used, or FET transistors (Field Effect Transistors) can be used. The capacitors 33a to 33f are snubber capacitors provided to absorb a transient high voltage generated when the transistors 31a to 31f are switched.

  Specifically, the transistors 31a, 31c, and 31e provided in the switching legs L11 to L13 have a collector electrode connected to one output terminal of the converter 11 (one electrode of the capacitor 12), and an emitter electrode connected to the transistor 31b, The collector electrodes 31d and 31f are connected to the collector electrodes, respectively. In addition, the transistors 31b, 31d, and 31f provided in the switching legs L11 to L13 have emitter electrodes connected to the other output end of the converter 11 (the other electrode of the capacitor 12). Base electrodes of these transistors 31 a to 31 f are connected to the control device 14. The diodes 32a to 32f and the capacitors 33a to 33f are connected between the collectors and emitters of the transistors 31a to 31f, respectively.

  Here, the connection point between the emitter electrode of the transistor 31a and the collector electrode of the transistor 31b forming the switching leg L11 is connected to one end P1 of the primary winding 23a of the high-frequency transformer 23 via the reactor 22. The connection point between the emitter electrode of the transistor 31c and the collector electrode of the transistor 31d that form the switching leg L12 is connected to the other end P2 of the primary winding 23a of the high-frequency transformer 23.

  Further, the connection point between the emitter electrode of the transistor 31e and the collector electrode of the transistor 31f forming the switching leg L13 is connected to the midpoint P3 of the primary winding 23a of the high-frequency transformer 23. The midpoint P3 here is not a narrow meaning of accurately dividing the primary winding 23a into two, but a broad meaning of an arbitrary point between one end P1 and the other end P2 of the primary winding 23a. The position is set according to the specifications of the charging device 1.

  The transistors 31c and 31d provided in the switching leg L12 and the transistors 31e and 31f provided in the switching leg L13 are exclusively driven by the control device 14. Therefore, each of the four transistors 31a to 31d provided in the switching legs L11 and L12 or the four transistors 31a, 31b, 31e and 31f provided in the switching legs L11 and L13 is set in accordance with a preset rule. By performing a switching operation (for example, a PWM switching operation), DC power from the converter 11 is converted into AC power and output to the reactor 22 side. On the other hand, for example, when all the transistors 31a to 31f are in the off state, when AC power is supplied from the reactor 22 side, the AC power is rectified by the diodes 32a to 32f and output to the converter 11.

  One end of the reactor 22 is connected to a connection point between the emitter electrode of the transistor 31a provided in the switching leg L11 and the collector electrode of the transistor 31b, and the other end of the primary side winding 23a provided in the high-frequency transformer 23. One end is connected to P1. This reactor 22 is provided to adjust the power factor. The other end P2 of the primary winding 23a is connected to the switching leg L12 (the connection point between the emitter electrode of the transistor 31c and the collector electrode of the transistor 31d), and the midpoint P3 of the primary winding 23a is It is connected to the switching leg L13 (the connection point between the emitter electrode of the transistor 31e and the collector electrode of the transistor 31f).

  The high-frequency transformer 23 includes the primary winding 23a and the secondary winding 23b described above. In the high-frequency transformer 23, the winding ratio of the secondary winding 23b with respect to the entire primary winding 23a (between one end P1 and the other end P2) is set to “6”, for example. The winding ratio of the secondary winding 23b to a part of 23a (between one end P1 and the middle point P3) is set to “10”, for example. The winding ratio can be arbitrarily set according to the specifications of the charging device 1. By providing the high-frequency transformer 23, the AC power source PS and the secondary battery B are insulated.

  The switch 24 is provided between the midpoint P3 of the primary winding 23a provided in the high-frequency transformer 23 and the switching leg L12 (a connection point between the emitter electrode of the transistor 31c and the collector electrode of the transistor 31d). Under the control of the device 14, they are short-circuited or opened. The switch 24 is provided to prevent a current from flowing through the switching leg L13 while driving the four transistors 31a to 31d provided in the switching legs L11 and L12.

  FIG. 2 is a circuit diagram illustrating an example of a switch provided in the charging apparatus according to the embodiment of the present invention. The switch shown in FIG. 2A is a bidirectional switch composed of two transistors and two diodes. In this bidirectional switch, when a control signal is applied to the base electrode of one transistor, current flows in one direction (for example, from the left side to the right side of the paper), and when a control signal is applied to the base electrode of the other transistor, the other direction (for example, Current flows from the right side to the left side of the page. Further, the switch shown in FIG. 2B is a relay switch such as an electromagnetic relay. In addition to the switches illustrated in FIGS. 2A and 2B, an electromagnetic contactor (contactor) can be used.

  The power conversion circuit 25 includes two switching legs L21 and L22 in which switching elements are connected in series, and AC power transferred from the primary side to the secondary side of the high-frequency transformer 23 under the control of the control device 14. Is converted to DC power and output to the output terminals T1 and T2. The power conversion circuit 25 can also convert DC power supplied from the output terminals T1 and T2 side into AC power and output the AC power to the secondary winding 23b of the high-frequency transformer 23.

  The switching leg L21 includes transistors 41a and 41b connected in series, a diode 42a and a capacitor 43a connected in parallel to the transistor 41a, and a diode 42b and a capacitor 43b connected in parallel to the transistor 41b. The switching leg L22 includes transistors 41c and 41d connected in series, a diode 42c and a capacitor 43c connected in parallel to the transistor 41c, and a diode 42d and a capacitor 43d connected in parallel to the transistor 41d.

  The transistors 41 a to 41 d are insulated gate bipolar transistors, similarly to the transistors 31 a to 31 f provided in the power conversion circuit 21, and the on state and the off state are controlled by the control device 14. As the transistors 41a to 41d, normal bipolar transistors or FET transistors can be used.

  Specifically, the transistors 41a and 41c provided in the switching legs L21 and L22 have collector electrodes connected to the output terminal T1 (one electrode of the capacitor 26) and emitter electrodes connected to the collector electrodes of the transistors 41b and 41d, respectively. It is connected. The transistors 41b and 41d provided in the switching legs L21 and L22 have their emitter electrodes connected to the output terminal T2 (the other electrode of the capacitor 26). Base electrodes of these transistors 41 a to 41 d are connected to the control device 14. The diodes 42a to 42d and the capacitors 43a to 43d are connected between the collectors and emitters of the transistors 41a to 41d, respectively.

  Here, the connection point between the emitter electrode of the transistor 41 a and the collector electrode of the transistor 41 b forming the switching leg L 21 is connected to one end of the secondary winding 23 b of the high-frequency transformer 23. The connection point between the emitter electrode of the transistor 41c and the collector electrode of the transistor 41d forming the switching leg L22 is connected to the other end of the secondary winding 23b of the high-frequency transformer 23.

  By switching each of the four transistors 41a to 41d provided in the switching legs L21 and L22 according to a preset rule (for example, PWM switching operation), from the output terminals T1 and T2 side (capacitor 26 side) Is converted to AC power and output to the secondary winding 23b of the high-frequency transformer 23. On the other hand, for example, when all of the transistors 41a to 41d are in the off state, when AC power is transferred from the primary side to the secondary side of the high-frequency transformer 23, the AC power is rectified by the diodes 42a to 42d and output. Output to the terminals T1 and T2 (capacitor 26). The capacitor 26 is connected between the output terminals T1 and T2 of the charging device 1, and smoothes the power rectified by the power conversion circuit 25 and converts it into DC power.

  The control device 14 controls charging of the secondary battery B connected to the output terminals T1 and T2. Specifically, according to the characteristics of the secondary battery B connected to the output terminals T1, T2, control of the converter 11, the power conversion circuits 31, 25 provided in the bidirectional DC / DC converter 13, and the switch 24 is performed. I do.

  Next, the operation when the secondary battery B is charged using the charging device 1 having the above-described configuration will be described. Note that the charging device 1 of the present embodiment controls each of the power conversion circuits 21 and 25 provided in the bidirectional DC / DC converter 13 when the power is transferred from the primary side to the secondary side of the high-frequency transformer 23. In this case, the amount of power transferred can be controlled. Here, for the sake of simplicity, a case where charging is performed by controlling only the power conversion circuit 21 will be described.

  First, the secondary battery B to be charged is connected to the charging device 1, and the positive electrode and the negative electrode of the secondary battery B are electrically connected to the output terminals T 1 and T 2 of the charging device 1, respectively. When the connection of the secondary battery B is completed, the control device 14 acquires information about the secondary battery B connected to the output terminals T1 and T2 (for example, information such as output voltage and remaining capacity). For example, as shown in FIG. 1, when the monitoring circuit D that monitors the secondary battery B is provided in the secondary battery B, information on the secondary battery B is acquired from the monitoring circuit D. A detection circuit that detects information such as the output voltage of the secondary battery B may be provided between the output terminals T1 and T2, and information about the secondary battery B may be acquired from the detection circuit.

  When the information about the secondary battery B is acquired, the control device 14 switches the on / off state of the switch 24 according to the acquired information. For example, when the output voltage of the secondary battery B is about several tens of volts, the switch 24 is turned off, and when the output voltage of the secondary battery B is about several hundred volts, the switch 24 is turned on. . That is, when the voltage of the secondary battery B is low, the middle point P3 of the primary side winding 23a of the high-frequency transformer 23 and the switching leg L13 are opened, and when the voltage of the secondary battery B is high, The middle point P3 of the primary side winding 23a of the high frequency transformer 23 and the switching leg L13 are short-circuited.

  When the above work and control are completed and an instruction to start charging is given, a control signal is output from the control device 14 to the power conversion circuit 21 provided in the bidirectional DC / DC converter 13, and provided in the power conversion circuit 21. The switching operation of the transistors 31a to 31f thus started is started. Specifically, when the voltage of the secondary battery B is low, among the six transistors 31a to 31f provided in the power conversion circuit 21, switching of the four transistors 31a to 31f provided in the switching legs L11 and L12 is performed. Operation starts. On the other hand, when the voltage of the secondary battery B is high, the switching operation of the four transistors 31a, 31b, 31e, 31f provided in the switching legs L11, L13 is started.

  Thus, the three-phase AC power supplied from the AC power source PS is converted into DC power by the converter 11, and the DC converted by the converter 11 by the switching operation of the transistors 31a to 31d or the transistors 31a, 31b, 31e, and 31f. Electric power is converted into AC power. The AC power converted by the power conversion circuit 21 is supplied to the primary winding 23 a of the high-frequency transformer 23 via the reactor 22.

  Here, when the voltage of the secondary battery B is low, the AC power converted by the switching operation of the transistors 31a to 31d is the primary side when the winding ratio of the high-frequency transformer 23 is low (the boost ratio is small). To the secondary side. For this reason, a voltage not so high (for example, about several tens of volts) is induced in the secondary winding 23b of the high-frequency transformer 23 according to the winding ratio. On the other hand, when the voltage of the secondary battery B is high, the AC power converted by the switching operation of the transistors 31a, 31b, 31e, and 31f has a high winding ratio of the high-frequency transformer 23 (a large boost ratio). State) is transferred from the primary side to the secondary side. For this reason, a high voltage (for example, about several hundred volts) corresponding to the winding ratio is induced in the secondary winding 23 b of the high-frequency transformer 23.

  The AC power transferred to the secondary side of the high-frequency transformer 23 is input to the power conversion circuit 25, rectified by diodes 41 a to 41 d provided in the power conversion circuit 25, smoothed by the capacitor 26, and converted to DC power. The This DC power is supplied to the secondary battery B via the connection terminals T1 and T2, thereby charging the secondary battery B. In this way, the secondary battery B is charged by the charging device 1.

  As described above, in the present embodiment, in addition to the switching legs L11 and L12 connected to the one end P1 and the other end P2 of the primary winding 23a of the high-frequency transformer 23, they are connected to the midpoint P3 of the primary winding 23a. Since the switching leg L13 is provided and the transistors provided in the switching legs L12 and L13 are exclusively switched according to the output voltage of the secondary battery B connected to the output terminals T1 and T2, a wide voltage range is achieved. The output voltage of the charging device 1 can be changed over this. Thereby, various kinds of secondary batteries can be efficiently charged using the charging device 1.

  As mentioned above, although the power converter device and charging device by one Embodiment of this invention were demonstrated, this invention is not restrict | limited to the said embodiment, It can change freely within the scope of the present invention. For example, in the embodiment described above, an example in which one middle point P3 is set in the primary winding 23a of the high-frequency transformer 23 and one switching leg L13 connected to the middle point P3 is provided. A plurality of midpoints may be set at different positions of the primary winding 23a, and a plurality of switching legs connected to each midpoint may be provided. With this configuration, the variable range of voltage can be set finely.

  In the above embodiment, the power conversion circuit 21 is provided with three switching legs and the power conversion circuit 25 is provided with two switching legs as an example. However, instead of the power conversion circuit 21 or together with the power conversion circuit 21, the power conversion circuit 25 may be configured to include three switching legs.

  Furthermore, in the said embodiment, it demonstrated taking the case of the charging device which charges the secondary battery B using the three-phase alternating current power supplied from alternating current power supply PS. However, the present invention can also be applied to a charging device that charges the secondary battery B using single-phase AC power.

DESCRIPTION OF SYMBOLS 1 Charging device 11 Converter 13 Bidirectional DC / DC converter 14 Control device 21, 25 Power conversion circuit 23 High frequency transformer 24 Switch 31a to 31f Transistor B Secondary battery L11 to L13 Switching leg P1 One end P2 Other end P3 Middle point PS AC power supply

Claims (4)

A high-frequency transformer, a first power conversion circuit provided on the primary side of the high-frequency transformer for converting DC power and AC power, and a conversion of DC power and AC power provided on the secondary side of the high-frequency transformer And a second power conversion circuit that performs DC power conversion.
At least one of the first and second power conversion circuits is connected to one end of a winding included in the high-frequency transformer, and a first switching leg formed by connecting switching elements in series;
A second switching leg connected to the other end of the winding and connected in series with switching elements;
At least one third switching leg connected to a midpoint between one end and the other end of the winding and connected in series with switching elements ;
A switch for short-circuiting or opening between the midpoint and the third switching leg;
When the switch is controlled to open the midpoint and the third switching leg, the switching elements provided in the first and second switching legs are controlled to control the switch. And a control device that controls the switching elements provided in the first and third switching legs when the midpoint and the third switching leg are short-circuited. Power converter. The power converter according to claim 1 , wherein the switch is a bidirectional switch, a relay switch, or a contactor. In a charging device that charges a secondary battery using AC power supplied from an AC power source,
A converter that converts AC power supplied from the AC power source into DC power;
A charging device comprising: the power conversion device according to claim 1 or 2 that performs conversion of DC power converted by the converter. The said control apparatus controls the said converter, the said 1st, 2nd power converter circuit, and the said switch according to the characteristic of the said secondary battery, The charging device of Claim 3 characterized by the above-mentioned.

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