JP3526262B2 - Power converter for power storage device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a power conversion device for a power storage device, and more particularly to charging a power storage means using a secondary battery with an AC input and discharging with an AC output. This is suitable for a power conversion device of a power storage device. 2. Description of the Related Art As a conventional power conversion device of a power storage device, a charging rectifier circuit for rectifying an AC power supply and a charging rectifier circuit as proposed in Japanese Patent Application Laid-Open No. 9-233710. A rectifier circuit for regeneration that regenerates the amount of electricity in the storage battery to the AC power supply, and a buck-boost converter provided between the rectification circuit for charging and the storage battery. Some are used as step-down converters and used as step-up converters during discharging. [0003] However, such a conventional power converter of a power storage device performs two-stage voltage conversion by a charging and regenerative rectifier circuit and a buck-boost converter during charging and discharging. Therefore, it becomes an expensive device,
The loss associated with the conversion increases, and the charge and discharge efficiency of the power storage device decreases. [0004] It is an object of the present invention to provide a power conversion device for a power storage device which can improve the charge and discharge efficiency of the power storage device with an inexpensive configuration. A first feature of the present invention to achieve the above object is to provide a power storage means using a secondary battery and an intermediate power supply by rectifying an AC input voltage from an AC power supply. A converter that converts the DC input voltage to a DC input voltage, a step-down chopper that steps down the intermediate DC input voltage and inputs the voltage to the power storage means, and an inverter that converts the DC output voltage from the power storage means to an AC output voltage; The step-down chopper is configured to step down the intermediate DC input voltage to an input DC voltage higher than the peak value of the AC output voltage, and the storage means is configured to step up the intermediate DC input voltage higher than the peak value of the AC output voltage. , So that the DC output voltage becomes higher than the peak value. A second feature of the present invention is that a step-down chopper that has a series circuit of a semiconductor switch element and a charging reactor and steps down an intermediate DC input voltage and inputs the stepped-down DC input voltage to a power storage means. A diode is reversely connected in parallel to a series circuit of the element and the charging reactor, and an intermediate DC output voltage input from the storage means via the diode is converted into an AC output voltage by an inverter. A third feature of the present invention is that the DC output voltage from the power storage means is converted into an AC output voltage by an inverter having a full bridge of the semiconductor switch element and a reactor connected in series to the AC output side thereof. That's what I did. A fourth feature of the present invention is that a bidirectional converter for rectifying an AC input voltage from an AC power supply to convert it into an intermediate DC input voltage and converting a DC output voltage from a power storage means to an AC output voltage. And a second reactor connected in series to the full bridge of the semiconductor switch element and its AC input / output side. A fifth feature of the present invention is that a storage means using a secondary battery, a converter for rectifying an AC input voltage from an AC power supply and converting it to an intermediate DC input voltage, and a step-down converter for reducing the intermediate DC input voltage. A step-down chopper for inputting the voltage to the power storage means, and an inverter for converting the DC output voltage from the power storage means to an AC output voltage, wherein the converter is configured to step up to an intermediate DC input voltage higher than the peak value of the AC input voltage. The step-down chopper is configured to step down the intermediate DC input voltage to an input DC voltage higher than the peak value of the AC output voltage, and the storage means is configured to have a DC output voltage higher than the peak value of the AC output voltage, Is that the DC output voltage from the power storage means is converted to an AC output voltage slightly higher than the AC input voltage. Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or corresponding components. First, a first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. First, a configuration of a power converter of a power storage device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of a power converter of a power storage device according to a first embodiment of the present invention. In FIG. 1, semiconductor switching elements 1a,
1b, 1c, 1d are connected in a full bridge configuration, and diodes 2a, 2b, 2c, 2d are reversely connected in parallel to the respective semiconductor switch elements 1a, 1b, 1c, 1d. Then, the semiconductor switch elements 1a, 1
One end of the charging / discharging reactor 3 is connected to the connection point b. These semiconductor switch elements 1a, 1b, 1c,
1d, the diodes 2a, 2b, 2c, 2d, and the charging / discharging reactor 3 constitute a bidirectional converter 22. The other end of the charging / discharging reactor 3 is connected to one end of a choke coil 4 and one end of a filter capacitor 5, and the other end of the choke coil 4 is connected to a changeover switch 6. Further, the semiconductor switch element 1c,
The connection point 1 d is connected to the other end of the filter capacitor 5 and the changeover switch 6 via the alternating current measurement sensor 7. The changeover switch 6 has a two-circuit transfer contact configuration. The break contact side is connected to the commercial power supply 8, and the make contact side is connected to the load 9. At the connection point between the semiconductor switches 1a and 1c,
One end of the smoothing capacitor 10 and the semiconductor switch element 11
, The cathode side of the diode 12, and the intermediate DC voltage detection unit 13 are connected. Further, a smoothing capacitor 10 is connected to a connection point of the semiconductor switches 1b and 1d.
, The anode side of the reflux diode 14, the intermediate DC voltage detection unit 13, the negative side of the storage means 16 formed of a secondary battery via the DC current measurement sensor 15, the DC voltage detection unit 17, One end of the filter capacitor 18 is connected. A parasitic diode 19 is reversely connected between the drain and the source of the semiconductor switch element 11, and a freewheel diode 14 is connected to the source side of the semiconductor switch element 11.
Of the charging reactor 20 and one end of the charging reactor 20. The other end of the charging reactor 20 has a diode 1
2, the DC voltage detector 17, the other end of the filter capacitor 18, and one end of the disconnect switch 21. The other end of the disconnect switch 21 is connected to the positive electrode side of the power storage means 16. The power storage means 16 is configured by connecting a plurality of lithium ion secondary batteries in series. The step-down chopper 26 includes the semiconductor switch element 11, the parasitic diode 19, the freewheeling diode 14, and the charging reactor 20. An AC voltage detection unit 23 is connected to both ends of the AC side input / output unit of the bidirectional converter 22, and an AC current measurement unit 24 is connected to the AC current measurement sensor 7. The AC current measurement unit 24, the AC voltage detection unit 23, and the intermediate DC voltage detection unit 13 are connected so that each piece of detection information is transmitted to the input / output control unit 25 that controls the bidirectional converter 22. A DC current detecting section 27 is connected to the DC current measuring sensor 15. The DC current detection unit 27, the intermediate DC voltage detection unit 13, and the DC voltage detection unit 17 are connected so that each detection information is transmitted to the charge control unit 28 that controls the step-down chopper 26. The device control unit 29 is connected so that information can be exchanged with the input / output control unit 25 and the charging control unit 28, and is connected so that the changeover switch 6 can be switched. Next, a charging / discharging operation of the power converter of the power storage device according to the present embodiment will be described with reference to FIGS. FIG. 2 is a voltage waveform diagram of each part of the power converter of FIG. In FIG. 2, reference numeral 30 denotes an AC input voltage, which indicates an AC voltage at a terminal portion of the AC input changeover switch 8 during charging.
An intermediate DC input voltage 31 is an intermediate DC capacitor 10 rectified and boosted by the bidirectional converter 22 during charging.
Shows the voltage between the terminals. 32 is a DC input voltage, which is a voltage between both terminals of the power storage means 16 of the DC input during charging. Reference numeral 36 denotes a DC output voltage, which indicates a voltage between terminals of the power storage means for DC output during discharging. Reference numeral 37 denotes an intermediate DC output voltage, which indicates a voltage between terminals of the intermediate DC capacitor 10 during discharging. Reference numeral 38 denotes an AC output voltage, which indicates the AC voltage at the terminal of the changeover switch 8 for the AC output during discharging. In this embodiment, the waveform of the AC input voltage 30 is the same as the voltage waveform of the commercial power supply 8. First, the operation of the power storage device of the present embodiment during charging of the power converter will be described. When the power storage device 16 is charged, a charge command signal is sent from the device control unit 29 to the changeover switch 6 to switch the changeover switch 6 to the commercial power supply 8 on the break contact side. Thus, the AC input having the voltage waveform of the AC input voltage 30 shown in FIG. 2 passes through the low-pass filter formed by the choke coil 4 and the filter capacitor 5 and is then input to the bidirectional converter 22.
The AC input voltage 30 is detected by the AC voltage detector 23 and the detection information is input to the input / output controller 25. According to the detection information of the AC voltage detection unit 23, the input / output control unit 25
Switching signal from the semiconductor switch element 1
a, 1b, 1c, 1d are input to the gates to control the on / off of the semiconductor switch elements 1a, 1b, 1c, 1d,
The input current waveform is monitored by the AC current measuring unit 24 and rectified and boosted while controlling it to have a substantially AC input waveform. The rectifying / boosting operation of the bidirectional converter 22 will be described in detail. When the voltage on the charging / discharging reactor 3 side of the AC input is positive, the current is changed to the semiconductor switch 1b, 1
When the switch c is turned on, the electric current is changed to the semiconductor switch element 1b, the diode 2d and the diode 2a,
c, and flows through the charge / discharge reactor 3
When the semiconductor switching elements 1b and 1c are turned off, the energy stored in the charging / discharging reactor 3 is stored in the diode 2a and the smoothing capacitor 1.
0, which flows through the diode 2d, whereby energy is stored in the smoothing capacitor 10. When the voltage of the AC input charging / discharging reactor 3 is negative, turning on the semiconductor switches 1a and 1d causes a current to flow through the semiconductor switching elements 1d and 2b and the diode 2c and semiconductor switching element 1a. , Energy is accumulated in the charging / discharging reactor 3 by the current, and
When the semiconductor switch elements 1a and 1d are turned off, the energy stored in the charging / discharging reactor 3 becomes the diode 2c,
Flows through the smoothing capacitor 10 and the diode 2b,
As a result, energy is stored in the smoothing capacitor 10. At this time, the amount of energy stored in the charging / discharging reactor 3 depends on the supplied current and the supplied time, and the voltage between the terminals of the smoothing capacitor 10, that is, the intermediate DC input voltage 31, depends on the amount of energy stored in the smoothing capacitor 10. By controlling the ON time of the semiconductor switch elements 1b, 1c and 1a, 1d, the AC input voltage 30 can be rectified and boosted to generate the intermediate DC input voltage 31. The full-bridge semiconductor switch elements 1a, 1b, 1c, 1
In the above description of the operation, d has been described as simultaneously turning on and off the diagonal semiconductor switch elements, respectively.
Control may be performed so as to be turned on / off individually. Then, from the device control unit 29 to the charge control unit 2
The high frequency switching signal is input from the charge control unit 28 to the gate of the semiconductor switch element 11 in response to the charge command signal to the battery 8, thereby operating the step-down chopper 26. The operation of the step-down chopper 26 will be described in detail. Information on the intermediate DC input voltage 31 detected by the intermediate DC detection unit 13, information on the DC input voltage 32 to the power storage means 16 detected by the DC voltage detection unit 17, and information on the DC current detected by the DC current detection unit 27 Is input to the charge control unit 28, and based on the input information, the charge control unit 28 controls the ON time of the high-frequency ON / OFF signal input to the gate of the semiconductor switch element 11 in the step-down chopper 26, 16 to control the charging voltage and current. In the operation of the step-down chopper 26, when the semiconductor switch element 11 is turned on, a current flows through the path of the smoothing capacitor 10, the semiconductor switch element 11, the charging reactor 20, the filter capacitor 18, the disconnecting switch 21 and the storage means 16, and the filter capacitor 18 Energy is stored in the charging reactor 20 while charging the battery and the power storage means 16. Note that the disconnect switch 21 is closed during charging. When the semiconductor switch element 11 is turned off, the energy stored in the charging reactor 20 causes a current to flow through the path of the filter capacitor 18, the separation switch 21, the storage means 16 and the return diode 14, and The means 16 is charged. The charge control unit 28 performs on / off control such that the charge current is continuous without interruption due to on / off of the semiconductor switch element 11. At this time, the DC input voltage 3
2 is always higher than the peak value of the AC input voltage 30, as shown in FIG. As a result, the current flowing through the power storage means 16 is reduced, so that the resistance loss proportional to the square of the current can be reduced, and the efficiency during charging can be improved. Next, the operation of the power converter of the power storage device according to the present embodiment at the time of discharging will be described. When discharging from the power storage means 16 to the load 9, the changeover switch 6 is switched to the load 9 on the make contact side and the disconnect switch 21 is closed according to a discharge command signal of the device control unit 29. If the disconnection switch 21 is closed without opening after the charging of the power storage means 16 is completed, it is not necessary to close it again. Disconnect switch 21
When the switch 21 is closed, the switch 21 and the diode 1 are disconnected from the power storage means 16 which becomes the DC output voltage 36 shown in FIG.
Discharge charge is supplied to the smoothing capacitor 10 through the second capacitor 2. Since the DC output voltage 36, which is the voltage between the terminals of the power storage means 16, is higher than the peak value of the AC output voltage 38, the current flowing through the power storage means 16 at the time of discharging becomes small, and the resistance loss is proportional to the square of the current. Can be reduced. The intermediate DC input voltage 37, which is the voltage between the terminals of the smoothing capacitor 10,
Has substantially the same waveform slightly lower than the inter-terminal voltage 36 of the power storage means 16, but is set to be always higher than the peak value of the AC output voltage 38 at the time of discharge. , The bidirectional converter 22 can be operated as an inverter to obtain a predetermined AC output voltage 38. Therefore, since a booster circuit is not required, the cost can be reduced, the loss accompanying the boosting conversion can be eliminated, and the efficiency at the time of discharging can be improved. In this case, the discharge current of the storage means 16 is
Although it is possible to flow through the charging reactor 20 and the parasitic diode 19 without using the diode 12, the forward voltage drop of the parasitic diode 19 is generally relatively large, the frequency characteristics are not so good, and the charging reactor is not so good. Because the impedance of 20 is also added,
If a discharge is attempted using the charging reactor 20 and the parasitic diode 19, the loss increases.
It is desirable to use 2. That is, the charging reactor 20
By bypassing the series circuit of the switch and the semiconductor switch 11 with the diode 12 reversely connected, the charging reactor 2
0 and the loss in the semiconductor switch 11 can be reduced, and the efficiency at the time of discharging can be improved. In particular, in the case of the present embodiment, since the power storage device operates in a self-sustaining manner, the maximum discharge current becomes significantly larger than the charging current, and the diode 12 has an appropriate current / voltage specification with a small forward voltage drop. By selecting and providing, the loss at the time of discharge can be significantly reduced. In order to convert the intermediate DC input voltage 37, which is the voltage between the terminals of the smoothing capacitor 10, to the AC output voltage 38 by the bidirectional converter 22, the device control unit 29
, A high-frequency on / off signal from the input / output unit 25 is applied to the gates of the semiconductor switch elements 1a, 1b, 1c and 1d of the bidirectional converter 22. During this discharge, the bidirectional converter 22 operates as an inverter. The operation of the bidirectional converter 22 as an inverter will be described in detail. When the semiconductor switch elements 1a and 1d are turned on by the signal of the input control unit 25, the charge stored in the smoothing capacitor 10 is transferred to the semiconductor switch element 1a, charge / discharge reactor 3, filter capacitor 5, choke coil 4, switch 6, load 9 Is discharged through the semiconductor switch element 1d as a path and flows as a current. At this time, energy is accumulated in the charging / discharging reactor 3, and when the semiconductor switching elements 1a, 1d are turned off, current is charged by the energy stored in the charging / discharging reactor 3, the charging / discharging reactor 3, the filter capacitor 5, and the choke coil 4. It flows through the series circuit of the switch 6 and the load 9, the diode 2c, the smoothing capacitor 10, and the diode 2b. At this time, the AC voltage detector 23
, The AC output current is monitored by the AC current measurement unit 24, and the AC output voltage is turned on by the input / output control unit 25 so that the waveform of the AC output voltage 38 becomes equivalent to the voltage waveform of the commercial power supply 8. • Control by adjusting the pulse width of the OFF signal. The peak value of the AC output waveform 31 increases as the ON pulse width increases. When the semiconductor switch elements 1b and 1c are turned on, a current flows through the semiconductor switch element 1c, a series circuit of the filter capacitor 5, the changeover switch 6, the load 9, and the choke coil 4, the charge / discharge reactor 3, the semiconductor switch element 1b, It flows on the path of the smoothing capacitor 10, and at this time, energy is stored in the charging / discharging reactor 3. When the semiconductor switch elements 1b and 1c are turned off, the current stored in the charge / discharge reactor 3 causes the current to flow through the charge / discharge reactor 3, the diode 2a, the smoothing capacitor 10,
The current flows through a series circuit path of the diode 2d, the filter capacitor 5, the changeover switch 6, the load 9, and the choke coil 4. In this way, the output of the bidirectional converter 22 operating as an inverter is AC, and the input / output control unit 25 uses the information from the AC voltage detection unit 23 to make the AC output equivalent to the voltage waveform of the commercial power supply 8. AC output voltage 3
8 is controlled. In the case of this embodiment, since the power storage device operates in a self-sustaining manner, the bidirectional converter 22 operating as an inverter is controlled by voltage control for keeping the output voltage constant. As described above, the inverter for converting the intermediate DC output voltage 37 into the AC output voltage 38 and outputting the same is connected in series to the full bridge of the semiconductor switch elements 1a, 1b, 1c and 1d and the AC output section. The configuration with the reactor 3 makes it possible to reduce the size and weight without using a transformer. Further, since the converter for converting AC input to intermediate DC and the inverter for converting intermediate DC to AC and outputting the same are the same bidirectional converter 22, a high-efficiency power converter can be provided with an inexpensive circuit. . Next, a power conversion device for a power storage device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram of a power converter of a power storage device according to a second embodiment of the present invention, and FIG. 4 is a voltage waveform diagram of each part of the power converter of FIG. First, the configuration of the present embodiment will be described with reference to FIG. 3. The load 9 is connected to the commercial power supply 8 in advance, and the load 9 is connected between the power conversion device of the power storage device and the commercial power supply 8 and the load 9. The power converter is connected to the commercial power supply 8 and the load 9 by the on / off switch 34. A commercial power supply waveform detection unit 35 is connected to the commercial power supply 8 side of the on / off switch 34.
Even when the power is cut off, the voltage waveform 30 of the commercial power supply 8 is monitored by the commercial power supply waveform detection unit 35. The other points are basically the same as those of the first embodiment, and the description is omitted. Next, the operation of the power converter of the power storage device according to the present embodiment will be described with reference to FIGS. At the time of charging, the charging operation is performed after the ON / OFF switch 34 is turned ON. The operation of the power converter of this embodiment at the time of charging is the same as that of the first embodiment, and a description thereof will be omitted. At the time of discharging, before the ON / OFF switch 34 is turned on, the AC input voltage 30 of the commercial power supply 8 is monitored by the commercial power supply waveform detection unit 35, and the bidirectional converter 22 operating as an inverter is operated. The AC output voltage 38 is monitored by the AC voltage detection unit 23, and the AC output voltage 38 slightly higher than the AC input voltage 30 of the commercial power supply 8 is output (see FIG. 4). Since the discharging operation of the other parts of the power converter is the same as that of the first embodiment, the description is omitted.
Next, the on / off switch 34 is turned on to superimpose the AC output waveform 38 on the commercial power supply waveform 36. At this time, the input / output control unit 25 monitors the output current by the AC current measurement unit 24 and controls the current so that the output current becomes constant. In the case of this embodiment, the output of the power storage means 16 is connected to the commercial power supply 8 so that the output current at the time of discharging becomes constant, so that the semiconductor switching elements 1a, 1b, 1c, 1d, diode 2
a, 2b, 2c, 2d, the charging / discharging reactor 3, the choke coil 4, the diode 12, and the disconnecting switch 21 can be selected from those having appropriate specifications that can reduce the component ratings and reduce the loss. Although the embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment. According to the present invention, it is possible to obtain a power storage device power conversion device that can improve the charge / discharge efficiency of the power storage device with an inexpensive configuration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block connection diagram of a power converter of a power storage device according to a first embodiment of the present invention. FIG. 2 is a voltage waveform diagram of each part of the power converter of FIG. FIG. 3 is a block diagram of a power converter of a power storage device according to a second embodiment of the present invention. 4 is a voltage waveform diagram of each part of the power converter of FIG. [Description of References] 1a, 1b, 1c, 1d ... Semiconductor switch elements, 2a,
2b, 2c, 2d: diode, 3: charge / discharge reactor (second reactor), 4: choke coil, 5: filter capacitor, 6: changeover switch, 7: AC current measurement sensor, 8: commercial power supply, 9: load 10: smoothing capacitor, 11: semiconductor switch element, 12: diode, 1
3 ... Intermediate DC voltage detection unit, 14 ... Reflux diode, 15
... DC current measurement sensor, 16 ... power storage means, 17 ... DC voltage detection unit, 18 ... filter capacitor, 19 ... parasitic diode, 20 ... charging reactor (first reactor),
21: disconnect switch, 22: bidirectional converter, 23
... AC voltage detecting unit, 24 ... AC current measuring unit, 25 ... Input / output control unit, 26 ... Step-down chopper, 27 ... DC current detecting unit, 28 ... Charging control unit, 29 ... Device control unit, 30 ... AC input voltage, 31 ... intermediate DC input voltage, 32 ... DC input voltage, 34 ... ON / OFF switch, 35 ... commercial power supply waveform detection unit,
36 ... DC output voltage, 37 ... Intermediate DC output voltage, 38 ...
AC output voltage.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-11-136879 (JP, A) JP-A-5-64456 (JP, A) JP-A-10-97330 (JP, A) JP-A 9-1997 233710 (JP, A) JP-A-62-68023 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 7/34 H01M 10/44 H02M 7/12 601 H02M 7/48

Claims (1)

(57) [Claims] [Claim 1] Rectifying an AC from an AC power supply to an intermediate DC,
A bidirectional converter that converts the intermediate DC into AC, the bi
Smoothing capacitor connected in parallel to the DC side of the directional converter
And the smoothing capacitor connected to this smoothing capacitor.
A step-down circuit for stepping down a voltage, and a step-down circuit connected to the step-down circuit.
Power storage means using a secondary battery , the step-down circuit,
Semiconductor switch element connected in parallel to the smoothing capacitor
Step-down chopper having a series circuit of a capacitor and a charging reactor
And a diode connected in anti-parallel to the series circuit.
Are those having, the bidirectional converter the controlled so as to boost the intermediate DC voltage to a higher voltage than the peak value of the input voltage of the AC, the step-down chopper of the AC output voltage of the voltage of the intermediate DC The voltage is controlled to drop to a DC input voltage higher than the peak value , the power storage unit is configured to have a DC output voltage higher than the peak value of the AC output voltage, and the bidirectional converter is
Converts intermediate DC input through the diode to AC
A power conversion device for a power storage device.