JP5530009B1 - Power supply - Google Patents

Abstract

Provided is a power supply device capable of independently setting output characteristics of individual devices when a plurality of devices are connected in parallel.
A power converter is controlled such that an alternating current Iac input / output at a terminal P1 and a voltage Vdc (voltage of a DC bus 7) at a terminal P2 have a relationship defined by a predetermined function. The predetermined function is changed according to the control signal Sc. Therefore, when operating by connecting a plurality of power supply apparatuses 10 in parallel, the output characteristics of each power supply apparatus 10 can be set independently.
[Selection] Figure 1

Description

  The present invention relates to a power supply device such as a DC-DC converter or a DC-AC inverter, and more particularly to a power supply device that can be operated by connecting a plurality of devices in parallel.

  When driving a large load, a plurality of power supply devices (also referred to as power conversion devices) such as a DC-DC converter or a DC-AC inverter may be connected in parallel. The following Patent Document 1 describes a method of operating PWM inverters in parallel.

  In the method of parallel operation of PWM inverters described in Patent Document 1, one of a plurality of inverters that are operated in parallel is a master PWM inverter, and the other is a slave PWM inverter. Each PWM inverter is equipped with a current sensor that detects the load current. Based on this detected current value, the difference between the load current of the master PWM inverter and the load current of the slave PWM inverter (current difference signal) is detected. Is done. The gate signal supplied to the switching element of the slave PWM inverter is generated by adjusting the pulse width of the gate signal supplied to the switching element of the master PWM inverter according to the current difference signal. That is, the gate signal of the slave PWM inverter is adjusted so that the load current of the slave PWM inverter matches the load current of the master PWM inverter.

JP 2008-5673 A

  In the system in which one of a plurality of power supply devices connected in parallel as described above is operated as a master and the other as a slave, the slave load current is determined according to the setting of the master load current. There is a problem that it cannot be set independently of the master. In addition, a dedicated cable for transmitting a control signal from the master to the slave is required, and a circuit for transmitting and receiving the control signal is also required, which causes a problem that the configuration is complicated. Furthermore, when there is a large delay in the control signal transmitted from the master to the slave, there is a problem that the load currents of the master and slave are out of synchronization. In addition, when the power supply device serving as the master stops due to a failure or the like, the slave power supply device also stops, resulting in a problem that the entire power supply system goes down.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power supply device capable of independently setting the output characteristics of each device when a plurality of devices are connected in parallel.

The power supply device according to the present invention includes a power converter that converts power input at the first terminal into power of a predetermined format and outputs the power from the second terminal, and a voltage detector that detects the voltage at the second terminal. The current input or output at the first terminal or the second terminal or the power and the voltage at the second terminal detected by the voltage detector have a relationship defined by a predetermined function. And a control unit for controlling the power conversion unit. The predetermined function indicates that as the voltage detected by the voltage detector increases, the power transmitted from the first terminal to the second terminal continuously decreases, and the voltage detected by the voltage detector decreases. As the power is transmitted, the power transmitted from the first terminal to the second terminal continuously increases, so that the current input or output at the first terminal or the second terminal or the power and the voltage detection unit detects the current. It is a function which prescribes | regulates the relationship with the voltage of the said 2nd terminal. The power conversion unit can transmit power bidirectionally between the first terminal and the second terminal. When the voltage detected by the voltage detection unit is lower than a predetermined first reference voltage, the control unit transmits power from the first terminal to the second terminal and is equal to the first reference voltage or When the detected voltage is higher than a second reference voltage higher than the first reference voltage, power is transmitted from the second terminal to the first terminal, and the detected voltage and the first reference voltage are transmitted. Alternatively, as the voltage difference from the second reference voltage increases, the power transmitted between the first terminal and the second terminal continuously increases according to the predetermined function, and as the voltage difference decreases, The power conversion unit is controlled so that the power transmitted between the first terminal and the second terminal continuously decreases according to the predetermined function.
Preferably, the control unit changes a constant in the predetermined function according to an input control signal, or one predetermined number of predetermined functions from a plurality of predetermined functions according to an input control signal. A function is selected, or the predetermined function is changed to another function according to information indicating the definition of the function included in the input control signal.

  According to the present invention, the power conversion unit is controlled so that the input or output current or the relationship between the current and the voltage is defined by a predetermined function, and the constants included in this function and the function itself are controlled. By changing according to the signal, the output characteristic of the power supply device can be set to a desired characteristic. Therefore, when operating a plurality of units connected in parallel, the output characteristic of each power supply device can be set independently.

It is a figure which shows an example of the power supply system comprised using the power supply device which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the power supply device which concerns on 1st Embodiment. It is a figure which shows an example of the relationship between the voltage input / output in the power supply device shown in FIG. 2, and an electric current. It is a figure for demonstrating the electric current input / output in each power supply device when a several power supply device is connected in parallel. It is a figure which shows an example of a structure of the power supply device which concerns on the 2nd Embodiment of this invention. FIG. 6 is a diagram illustrating an example of a relationship between voltage and current input / output in the power supply device illustrated in FIG. 5.

<First Embodiment>
FIG. 1 is a diagram illustrating an example of a power supply system configured using the power supply device according to the first embodiment of the present invention.
The power supply system shown in FIG. 1 is a system that transmits power to each other via a DC bus 7 between an AC system line 1, a solar power generation device 2, a storage battery 3, and a load 4, and is connected in parallel to the AC system line 1. The power supply device 10 includes a plurality of power supply devices 10, a power supply device 20 connected to the solar power generation device 2, a power supply device 30 connected to the storage battery 3, and a power supply device 40 connected to the load 4. The power supply device 10 is a power supply device according to the first embodiment of the present invention.

  The power supply device 10 is a power conversion device that transmits power between the AC system line 1 and the DC bus 7, and can transmit power, for example, in both directions. Specifically, the power supply device 10 converts the AC power input from the AC system line 1 into DC power and outputs the DC power to the DC bus 7 and the DC power input from the DC bus 7 as AC. It has an operation mode (regeneration mode) in which it is converted into electric power and output to the AC system line 1.

  Each power supply device 10 connected in parallel is connected to the AC system line 1 via a transformer 5 as shown in FIG. The transformer 5 prevents a direct current from flowing from the power supply device 10 to the AC system line 1 and prevents a direct current circulating current from flowing between the power supply devices 10 connected in parallel.

  The power supply device 20 is a power conversion device (DC-DC converter) that outputs DC power generated in the solar power generation device 2 to the DC bus 7. For example, a relatively low voltage of the solar power generation device 2 is applied to the DC bus 7. Boosts to a high voltage Vdc.

  The power supply device 30 is a power conversion device (DC-DC converter) that transmits power between the storage battery 3 and the DC bus 7, and can transmit power in both directions, for example. Specifically, the power supply device 30 outputs an operation mode (discharge mode) for outputting DC power input from the storage battery 3 to the DC bus 7 and an operation mode (charging) for outputting DC power input from the DC bus 7 to the storage battery 3. Mode). Power supply device 30 boosts the relatively low voltage of storage battery 3 to a relatively high voltage Vdc of DC bus 7 in the discharge mode, and reduces the DC voltage Vdc of DC bus 7 to the voltage of storage battery 3 in the charging mode.

  The power supply device 40 is a power conversion device (DC-DC converter) that outputs DC power input from the DC bus 7 to the load 4. The power supply device 40 steps down or boosts the voltage of the DC bus 7 to a voltage necessary for the load 4.

  The power supply devices 20 to 40 insulate the input from the output by, for example, a high frequency transformer. Thereby, since the solar power generation device 2, the storage battery 3, and the load 4 are insulated from each other, it is possible to prevent a ground fault current or the like from flowing through the power supply system.

FIG. 2 is a diagram showing an example of the configuration of the power supply device 10 in the power supply system shown in FIG.
The power supply device 10 illustrated in FIG. 2 includes a power conversion unit 11, a control unit 12, an AC voltage detection unit 13, an AC current detection unit 14, and a DC voltage detection unit 15.
The power conversion unit 11 is an example of a power conversion unit in the present invention.
The DC voltage detector 15 is an example of a voltage detector in the present invention.
The control unit 12 is an example of a control unit in the present invention.

  The power conversion unit 11 has a terminal P1 connected to the AC system line 1 via the transformer 5 and a terminal P2 connected to the DC bus 7, and power is supplied bidirectionally between the terminal P1 and the terminal P2. Tell. That is, the power conversion unit 11 converts AC power from the AC system line 1 input to the terminal P1 into DC power in the powering mode and outputs the DC power from the terminal P2 to the DC bus 7. In the regeneration mode, the power conversion unit 11 The input DC power is converted into AC power and output from the terminal P1.

As shown in FIG. 2, for example, the power conversion unit 11 includes an H bridge circuit 110, a drive circuit 115, an inductor L1, and capacitors C1 and C2.
The H-bridge circuit 110 has four semiconductor switch elements (n-type MOSFETs in the example of FIG. 2), and is connected to the terminal P1 according to the drive signal supplied from the drive circuit 115 to each semiconductor switch element. Each of the AC lines is connected to one of the high potential side line and the low potential side line of the DC bus 7.
The drive circuit 115 outputs a drive signal for turning on or off each semiconductor switch element of the H bridge circuit 110 according to the control signal supplied from the control circuit 12.
The inductor L1 and the capacitor C2 constitute a filter for smoothing the rectangular wave voltage generated in the H bridge circuit 110, and are provided on an AC line connecting the H bridge circuit 110 and the terminal P1. .
The capacitor C <b> 1 is for suppressing the vibration of the voltage of the DC bus 7 caused by the current flowing through the H bridge circuit 110, and is provided at the connection portion between the H bridge circuit 110 and the DC bus 7.

  The AC voltage detector 13 detects the AC voltage Vac at the terminal P1, and the DC voltage detector 15 detects the voltage Vdc of the DC bus 7. The AC voltage detection unit 13 and the DC voltage detection unit 15 include, for example, an amplifier (such as a differential amplifier) that detects by lowering the voltage level.

  The alternating current detection unit 14 is a circuit that detects the alternating current Iac input / output at the terminal P1, and includes a current sensor such as a current transformer, a resistor (shunt resistor), and a magnetic sensor.

The control unit 12 is a circuit that generates a control signal for controlling power conversion between direct current power and alternating current power in the power conversion unit 11, and specifically, as shown in FIG. A control signal for controlling on or off of the semiconductor switch element included in the main circuit of the unit 11 (H bridge circuit 110 in the example of FIG. 2) is generated.
The control unit 12 includes, for example, a microprocessor (DSP or the like) that executes processing based on a program. The control unit 12 converts the detection signals output from the AC voltage detection unit 13, the AC current detection unit 14, and the DC voltage detection unit 15 into digital signals (analog-digital conversion) and inputs them, and according to these detection signals. The control signal is generated and supplied to the drive circuit 115 of the power converter 11.

The control unit 12 controls the control signal of the power conversion unit 11 so that the AC current Iac input / output at the terminal P1 and the voltage Vdc (voltage of the DC bus 7) at the terminal P2 have a relationship defined by a predetermined function. Is generated.
Specifically, when the voltage Vdc of the DC bus 7 detected by the DC voltage detection unit 15 is lower than the reference voltage V0, the control unit 12 transmits power from the terminal P1 to the terminal P2 (powering mode), and the DC voltage When the voltage Vdc detected by the detection unit 15 is higher than the reference voltage V0, a control signal for the power conversion unit 11 is generated so that power is transmitted from the terminal P2 to the terminal P1 (regeneration mode). In addition, as the voltage difference between the voltage Vdc detected by the DC voltage detection unit 15 and the reference voltage V0 increases, the control unit 12 continuously increases the power transmitted between the terminals P1 and P2 according to a predetermined function. As the voltage difference increases and the voltage difference decreases, a control signal for the power converter 11 is generated so that the power transmitted between the terminals P1 and P2 continuously decreases according to a predetermined function.

  FIG. 3 is a diagram showing an example of the relationship between voltage Vdc and current Iac in power supply device 10 shown in FIG. The vertical axis of the graph in FIG. 3 indicates the voltage Vdc, and the horizontal axis indicates the current Iac (the amplitude or effective value of the AC signal). Note that the polarity of the current Iac in the graph of FIG. 3 is positive when power is input from the AC system line 1 to the power supply device 10 (powering mode), and the power is output from the power supply device 10 to the AC system line 1. The polarity of the regenerative mode (regenerative mode) is negative. The polarity of the current Iac is positive on the right side of zero on the horizontal axis and negative on the left side of zero.

In the graph shown in FIG. 3, the voltage Vdc and the current Iac are in a proportional relationship. When the voltage Vdc matches the reference voltage V0, the current Iac is zero.
When the voltage Vdc is lower than the reference voltage V0, the positive current Iac increases in proportion to the voltage drop from the reference voltage V0, and the power input from the AC system line 1 to the power supply device 10 increases. In this case, since a current flows from the power supply device 10 to the DC bus 7, the DC bus voltage Vdc changes in an increasing direction.
On the other hand, when voltage Vdc becomes higher than reference voltage V0, negative current Iac increases in proportion to the excess voltage from reference voltage V0, and the power output from power supply device 10 to AC system line 1 increases. In this case, since a current flows from the DC bus 7 to the power supply device 10, the voltage Vdc of the DC bus changes in a decreasing direction.

Further, the control unit 12 changes the function that defines the relationship between the current Iac and the voltage Vdc as shown in the graph of FIG. 3 in accordance with a control signal Sc input from a host computer (higher-order device) or the like.
For example, the control unit 12 changes a constant included in the function (a coefficient or a constant term included in a function represented by a polynomial or the like) according to the control signal Sc. When the voltage Vdc and the current Iac are in a proportional relationship, the proportionality coefficient (gradient of the graph) can be changed according to the control signal Sc, for example, as represented by a dotted line graph in FIG.

As another example, the control unit 12 may select one from a plurality of predetermined functions according to the control signal Sc, and use this as a new function. Or the control part 12 may change a predetermined function into another function according to the information (information of the formula of a function, etc.) which shows the definition of the function contained in the control signal Sc input.
Thus, in the present embodiment, the function that defines the relationship between the current Iac and the voltage Vdc can be changed for each power supply device 1. Therefore, even when operating by connecting a plurality of power supply devices 10 in parallel, the output characteristics of each power supply device 1 can be set independently.

  The control unit 12 includes a voltage control unit 120 and a target voltage setting unit 122 as functional blocks.

  The voltage control unit 120 is a block that generates a control signal for the power conversion unit 11 so that the voltage Vdc detected by the DC voltage detection unit 15 approaches the target voltage set by the target voltage setting unit 122. FIG. In the example, a target current setting signal generation unit 1201 and a control signal generation unit 1202 are included.

The control signal generation unit 1202 generates a control signal for the power conversion unit 11 so that a current Iac corresponding to the target current setting signal Iset generated by the target current setting signal generation unit 1201 is input or output at the terminal P1. .
The target current setting signal generation unit 1201 generates the target current setting signal Iset so that the voltage Vdc detected by the DC voltage detection unit 15 approaches the target voltage set by the target voltage setting unit 122.

  In a more specific example illustrated in FIG. 2, the target current setting signal generation unit 1201 includes an error calculation unit 1203 and a PI control unit 1204. The control signal generation unit 1202 includes a reference AC signal generation unit 1205, a multiplication unit 1206, an error calculation unit 1207, a PI control unit 1208, a carrier signal generation unit 1209, and a pulse signal generation unit 1210.

The error calculator 1203 calculates the difference between the detected value of the voltage Vdc output from the DC voltage detector 15 and the target voltage setting signal Vset of the voltage Vdc output from the target voltage setting unit 122.
The PI control unit 1204 performs a PI calculation (proportional / integral calculation) on the difference between the detected value of the voltage Vdc calculated by the error calculation unit 1203 and the target voltage setting signal Vset, and a target indicating the target value of the amplitude of the current Iac. A current setting signal Iset is generated. That is, the PI control unit 1204 calculates the integration element calculated by multiplying the output of the error calculation unit 1203 by a predetermined integral gain, and the proportional element calculated by multiplying the output of the error calculation unit 1203 by a predetermined proportional gain. And the addition result is output as the target current setting signal Iset.

The reference AC signal generator 1205 generates a reference AC signal whose frequency and phase coincide with those of the AC voltage Vac based on the detection result of the AC current detector 14.
Multiplier 1206 multiplies the reference AC signal generated by reference AC signal generator 1205 by target current setting signal Iset, and outputs the multiplication result as a target instantaneous value of current Iac.

Error calculator 1207 calculates the difference between the instantaneous value of AC current Iac detected by AC current detector 14 and the target instantaneous value of current Iac output from multiplier 1206.
The PI control unit 1208 performs PI calculation on the difference between the instantaneous value of the alternating current Iac calculated by the error calculation unit 1207 and the target instantaneous value. That is, the PI control unit 1208 multiplies the output of the error calculation unit 1207 by a predetermined integral gain and integrates it, and the proportional element calculated by multiplying the output of the error calculation unit 1207 by a predetermined proportional gain. And add.

The carrier signal generator 1209 generates a triangular wave carrier signal having a frequency sufficiently higher than the frequency of the AC system line 1.
The pulse signal generation unit 1210 is configured to turn on and off each semiconductor switch element included in the power conversion unit 11 based on the PI calculation result signal in the PI control unit 1208 and the carrier signal generated by the carrier signal generation unit 1209. A pulse signal for controlling is generated.
The above is the description of the voltage control unit 120.

  The target voltage setting unit 122 is based on a signal indicating the current Iac input or output at the terminal P1, and a relationship defined by a predetermined function with the current Iac indicated by the signal (for example, the graph of FIG. 3 shows The target value of the voltage Vdc at the terminal P2 is set so as to satisfy (Relationship).

Specifically, when the current Iac has a positive polarity (polarity for inputting power from the AC system line 1 to the power conversion unit 11), the target voltage setting unit 122 increases the voltage Vdc as the effective value of the current Iac increases. Is continuously decreased, and the target voltage of the voltage Vdc is set so that the voltage Vdc continuously increases as the effective value of the current Iac decreases.
When the current Iac has a negative polarity (polarity for outputting power from the power conversion unit 11 to the AC system line 1), the target voltage setting unit 122 continuously increases the voltage Vdc as the effective value of the current Iac increases. Thus, the target voltage of the voltage Vdc is set so that the voltage Vdc continuously decreases as the effective value of the current Iac decreases.
When the current Iac is zero, the target voltage setting unit 122 sets the reference voltage V0 as the target voltage of the voltage Vdc.
Thereby, the power conversion unit 11 operates in the power running mode when the voltage Vdc is lower than the reference voltage V0, operates in the regeneration mode when the voltage Vdc is higher than the reference voltage, and the voltage Vdc matches the reference voltage V0. The current Iac becomes zero. Accordingly, the plurality of power supply devices 10 connected in parallel to the common DC bus 7 all operate in the same mode (power running mode or regenerative mode).

The target voltage setting unit 122 refers to, for example, the target current setting signal Iset as a signal indicating the current Iac input or output at the terminal P1. The target voltage setting unit 122 generates a target voltage setting signal Vset having a relationship defined by the target current setting signal Iset and a predetermined function by performing a predetermined calculation on the target current setting signal Iset.
Alternatively, the target voltage setting unit 122 may include a data table that defines the correspondence relationship between the target current setting signal Iset and the target voltage setting signal Vset. In this case, the target voltage setting unit 122 may read the target voltage setting signal Vset corresponding to the input target current setting signal Iset from the data table.

  The target voltage setting unit 122 sets the reference voltage V0 as the target value of the voltage Vdc of the DC bus 7 when the target current setting signal Iset that makes the current Iac input or output at the terminal P1 zero is generated.

  Further, the target voltage setting unit 122 may change a function that defines the relationship between the target current setting signal Iset and the target voltage setting signal Vset in accordance with a control signal Sc input from a host computer (higher-order device) or the like. it can. For example, the target voltage setting unit 122 changes a constant included in the function according to the control signal Sc, selects a new function from a plurality of predetermined functions according to the control signal Sc, For example, a predetermined function is changed to another function based on function definition information (such as information on a function formula) included in Sc.

Here, the operation of the power supply system shown in FIG. 1 will be described.
The power supply device 20 inputs the electric power generated in the solar power generation device 2 and outputs a current to the DC bus 7 as a current source, for example.
The power supply device 40 receives DC power from the DC bus 7 and supplies a voltage obtained by stepping down or boosting the voltage Vdc to the load 4.

  The power supply device 30 monitors the state of charge of the storage battery 3 and charges the storage battery 3 by inputting power from the DC bus 7 so that an appropriate state of charge is maintained. When the voltage Vdc of the DC bus 7 falls below the reference voltage V0, the power supply device 30 discharges the storage battery 3 within the range of an appropriate charging state and outputs the power to the DC bus 7.

  The voltage Vdc of the DC bus 7 changes according to the power input / output in the power supply devices 20-40. When the voltage Vdc of the DC bus 7 becomes higher than the reference voltage V0, the power supply devices 10 connected in parallel operate in the regeneration mode, and output power from the DC bus 7 to the AC system line 1, thereby Reduce. When the voltage Vdc of the DC bus 7 becomes lower than the reference voltage V0, each power supply device 10 operates in the power running mode, and inputs power from the AC system line 1 to the DC bus 7, thereby increasing the voltage of the DC bus 7. Thereby, the voltage Vdc of the DC bus 7 is maintained at a voltage close to the reference potential V0.

  As described above, according to the power supply device 10 according to the present embodiment, the AC current Iac input / output at the terminal P1 and the voltage Vdc (voltage of the DC bus 7) at the terminal P2 are defined by a predetermined function. The power conversion unit 11 is controlled to have a relationship, and this predetermined function is changed according to the control signal Sc. Therefore, when operating by connecting a plurality of power supply apparatuses 10 in parallel, the output characteristics of each power supply apparatus 10 can be set independently.

Further, according to the power supply device 10 according to the present embodiment, the function of the alternating current Iac and the voltage Vdc can be set by the control signal Sc. Therefore, when a plurality of power supply devices 10 are connected in parallel, The size can be set arbitrarily.
FIG. 4 is a diagram for explaining currents input and output in each power supply device 10 when a plurality of power supply devices 10 are connected in parallel. In the example of FIG. 4, the AC current Iac input / output at the terminal P1 and the voltage Vdc at the terminal P2 are proportional to each power supply device 10, and the proportionality coefficient (slope of the graph) is different for each power supply device 10. It is set to a different value. As shown in FIG. 4, since the functions of the alternating current Iac and the voltage Vdc in the power supply device 10 can be individually set, when a plurality of power supply devices 10 are connected in parallel, each power supply device 10 at a specific voltage (Va) The magnitude (I1, I2) of the alternating current Iac can be arbitrarily set.

  Furthermore, according to the power supply device 10 according to the present embodiment, since the alternating current Iac and the voltage Vdc have a relationship defined by a predetermined function, even when a plurality of power supply devices 10 are connected in parallel. By measuring the voltage Vdc at the terminal P2, the magnitude of the alternating current Iac flowing through each power supply device 10 can be easily estimated.

Moreover, according to the power supply device 10 according to the present embodiment, when the voltage Vdc detected by the voltage detection unit 15 is lower than the reference voltage V0, power is transmitted from the terminal P1 to the terminal P2 (powering mode), and voltage detection is performed. When the voltage Vdc detected in the unit 15 is higher than the reference voltage V0, the power conversion unit 11 is controlled so that power is transmitted from the terminal P2 to the terminal P1 (regeneration mode). Further, as the voltage difference between the voltage Vdc detected by the voltage detector 15 and the reference voltage V0 increases, the power transmitted between the terminal P1 and the terminal P2 continuously increases according to a predetermined function, and this voltage difference The power conversion unit 11 is controlled so that the power transmitted between the terminal P1 and the terminal P2 continuously decreases according to a predetermined function as becomes smaller.
If each power conversion unit 11 is controlled so that the voltage Vdc at the terminal P2 becomes a constant voltage (assuming that a general constant voltage control is performed at the terminal P2), a plurality of such power conversion units is used. If 11 are connected in parallel, a load will concentrate on a part of the power converters 11 due to slight variations in the target voltage. Such a phenomenon generally occurs when the outputs of a plurality of constant voltage sources are connected in parallel. On the other hand, in the power supply device 10 according to the present embodiment, the power transmitted between the terminal P1 and the terminal P2 changes continuously as described above in accordance with the change in the voltage Vdc of the terminal P2, so Even when the power supply devices 10 are connected in parallel, load concentration due to variations in the target voltage at the terminal P2 can be effectively suppressed.

  Further, according to the power supply device 10 according to the present embodiment, when the voltage Vdc at the terminal P1 becomes the reference voltage V0, the power transmitted between the terminal P1 and the terminal P2 becomes zero, and the voltage Vdc becomes the reference voltage. When it is lower than V0, it becomes a power running mode in which power is transmitted from the terminal P1 to the terminal P2, and when the voltage Vdc is higher than the reference voltage V0, it becomes a regeneration mode in which power is transmitted from the terminal P2 to the terminal P1. As a result, when a plurality of power supply devices 10 are connected in parallel, all the power supply devices 10 operate in the same mode (powering mode or regenerative mode), so power is circulated wastefully between the power supply devices 10. It is possible to effectively prevent a phenomenon (a phenomenon in which electric power circulates between a device operating in the power running mode and a device operating in the regenerative mode).

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 5 is a diagram illustrating an example of the configuration of the power supply device 10 according to the second embodiment.

The power supply device 10 shown in FIG. 5 is obtained by changing the control unit 12 in the power supply device 10 shown in FIG. 2 to a control unit 12A, and the other configuration is the same as that of the power supply device 10 shown in FIG.
The control unit 12A controls the power conversion unit 11 so that the alternating current Iac input / output at the terminal P1 and the voltage Vdc of the terminal P2 (the voltage of the direct current bus 7) have a relationship defined by a predetermined function. The control signal is generated, and this point is the same as the control unit 12 described above. The difference between the control unit 12A and the control unit 12 is the condition of the voltage Vdc that makes the power transmitted between the terminal P1 and the terminal P2 zero. That is, the control unit 12 is conditional on the voltage Vdc being equal to the reference voltage V0, whereas the control unit 12A is conditional on the voltage Vdc being between two reference voltages (V1, V2). .

Specifically, when the voltage Vdc of the DC bus 7 detected by the DC voltage detection unit 15 is in the range of the reference voltage V1 or more and the reference voltage V2 or less (where V2> V1), the control unit 12A detects the terminal P1. The control signal of the power converter 11 is generated so that the power transmitted between the terminal P2 and the terminal P2 becomes zero.
On the other hand, when the voltage Vdc of the DC bus 7 detected by the DC voltage detection unit 15 is lower than the reference voltage V1, the control unit 12A transmits power from the terminal P1 to the terminal P2 (powering mode), and the DC voltage detection unit 15 When the detected voltage Vdc is higher than the reference voltage V2, a control signal for the power converter 11 is generated so that power is transmitted from the terminal P2 to the terminal P1 (regeneration mode).
In addition, as the voltage difference between the voltage Vdc detected by the DC voltage detection unit 15 and the reference voltage V1 or V2 increases, the control unit 12A causes the power transmitted between the terminal P1 and the terminal P2 to continue according to a predetermined function. As the voltage difference decreases, the control signal of the power converter 11 is generated so that the power transmitted between the terminals P1 and P2 continuously decreases according to a predetermined function.

The control unit 12A includes a voltage control unit 120 similar to the control unit 12 and a target voltage setting unit 122A as functional blocks.
Similar to the target voltage setting unit 122 described above, the target voltage setting unit 122A satisfies the relationship defined by a predetermined function with the current Iac indicated by the signal based on the signal indicating the current Iac. The target value of the voltage Vdc at the terminal P2 is set. However, the target value setting method when the current Iac is zero is different from that of the target voltage setting unit 122.

That is, when the current Iac is zero in the signal indicating the current Iac (the target current setting signal Iset in the example in the figure), the target voltage setting unit 122A has a detection value of the voltage Vdc in the DC voltage detection unit 15 equal to or higher than the reference voltage V1. It is determined whether or not it is within the range of the reference voltage V2.
When the detected value of voltage Vdc is within this range, target voltage setting unit 122A sets the detected value of voltage Vdc as the target value of voltage Vdc. Thereby, as long as the detected value of voltage Vdc is in the range of reference voltage V1 or more and reference voltage V2 or less, power conversion unit 11 is controlled so that current Iac is maintained at zero.
When the detected value of the voltage Vdc is lower than the reference voltage V1, the target voltage setting unit 122A sets the reference voltage V1 closest to the detected value of the voltage Vdc as a target value of the voltage Vdc under the condition that the current Iac becomes zero.
When the detected value of voltage Vdc is higher than reference voltage V2, target voltage setting unit 122A sets reference voltage V2 that is closest to the detected value of voltage Vdc as the target value of voltage Vdc under the condition that current Iac is zero. To do.

  FIG. 6 is a diagram showing an example of the relationship between voltage Vdc and current Iac in power supply device 10 shown in FIG. In the graph shown in FIG. 6, when the voltage Vdc is within the range from the reference voltage V1 to the reference voltage V2, the current Iac is zero. In other ranges, the voltage Vdc and the current Iac are in the same proportional relationship as in FIG.

As described above, according to the power supply device 10 according to the present embodiment, when the detected value of the voltage Vdc of the DC bus 7 is in the range of the reference voltage V1 or more and the reference voltage V2 or less, the terminal P1 and the terminal P2 The power converter 11 is controlled so that the electric power transmitted between them becomes zero.
Therefore, in the case where the plurality of power supply devices 10 are connected in parallel and operated, the range of the reference voltages V1 to V2 is within the variation range even if the magnitudes of the reference voltages V1 and V2 vary somewhat in the individual power supply devices 10. By setting it to be larger than that, it is possible to reliably prevent useless power circulation due to the simultaneous presence of the power supply device 10 in the power running mode and the power supply device 10 in the regeneration mode.

  In addition, this invention is not limited only to embodiment mentioned above, Various modifications are included.

In the above-described embodiment, an example of a power supply device including a power conversion unit that bidirectionally converts DC power and AC power is given, but the present invention is not limited to this example. For example, the present invention can also be applied to a power supply device including a power conversion unit that performs conversion in one direction from DC power to AC power or from AC power to DC power.
In addition, the form of power to be converted in the power conversion unit is not limited to the above example, and includes, for example, a power conversion unit (DC-DC converter) that converts DC power and DC power bidirectionally or unidirectionally. The present invention can also be applied to power supply devices. Specifically, for example, the present invention may be applied to the power supply device 30 for charging / discharging in FIG. 1 so that a plurality of units can be connected in parallel.

  In the embodiment described above, an example is given in which the power converter 11 is controlled so that the current Iac input or output at the terminal P1 and the voltage Vdc of the terminal P2 have a relationship defined by a predetermined function. The present invention is not limited to this example. In another embodiment of the present invention, the power converter 11 may be controlled such that the direct current input or output at the terminal P2 and the voltage Vdc of the terminal P2 have a relationship defined by a predetermined function. . In still another embodiment of the present invention, the power converter 11 is provided so that the power input or output at the terminal P1 or the terminal P2 and the voltage Vdc of the terminal P2 have a relationship defined by a predetermined function. You may control.

  In the embodiment described above, the target current setting signal Iset is referred to as the signal indicating the current Iac input or output at the terminal P1, and the target voltage setting signal Vset corresponding to the target current setting signal Iset is generated. The present invention is not limited to this example. For example, in another embodiment of the present invention, the effective value of the current Iac is calculated based on the detection signal of the current Iac in the alternating current detection unit 14, and the target voltage setting signal Vset corresponding to the calculated effective value is generated. May be.

  Regarding the technical idea of the present invention grasped based on the above-described embodiment, the following additional notes are disclosed.

[Appendix 1]
A power converter that converts power input at the first terminal into power of a predetermined format and outputs the power from the second terminal;
A voltage detector for detecting the voltage of the second terminal;
The current or power input or output at the first terminal or the second terminal and the voltage at the second terminal detected by the voltage detector have a relationship defined by a predetermined function. And a control unit that controls the power conversion unit.

[Appendix 2]
The controller is
Changing a constant in the predetermined function according to an input control signal;
Or
According to an input control signal, one predetermined function is selected from a plurality of predetermined functions.
Or
According to the information indicating the definition of the function included in the input control signal, the predetermined function is changed to another function.
The power supply device according to appendix 1.

[Appendix 3]
As the voltage detected by the voltage detector increases, the control unit continuously decreases the power transmitted from the first terminal to the second terminal according to the predetermined function, and the detected voltage decreases. As it becomes, the power conversion unit is controlled so that the power transmitted from the first terminal to the second terminal continuously increases according to the predetermined function.
The power supply device according to appendix 1 or 2.

[Appendix 4]
The power conversion unit can transmit power bidirectionally between the first terminal and the second terminal,
When the voltage detected by the voltage detection unit is lower than a predetermined first reference voltage, the control unit transmits power from the first terminal to the second terminal and is equal to the first reference voltage or When the detected voltage is higher than a second reference voltage higher than the first reference voltage, power is transmitted from the second terminal to the first terminal, and the detected voltage and the first reference voltage are transmitted. Alternatively, as the voltage difference from the second reference voltage increases, the power transmitted between the first terminal and the second terminal continuously increases according to the predetermined function, and as the voltage difference decreases, Controlling the power conversion unit so that the power transmitted between the first terminal and the second terminal continuously decreases according to the predetermined function;
The power supply device according to attachment 3.

[Appendix 5]
When the detected voltage is in a range not less than the first reference voltage and not more than the second reference voltage, the control unit is configured such that the power transmitted between the first terminal and the second terminal becomes zero. Controlling the power conversion unit,
The power supply device according to appendix 4.

[Appendix 6]
The controller is
Based on a signal indicating current or power input or output at the first terminal or the second terminal so as to satisfy the relationship defined by the predetermined function with the current or power indicated by the signal. A target voltage setting unit for setting a target voltage of the second terminal;
A voltage control unit that controls the power conversion unit so that the voltage of the second terminal detected by the voltage detection unit approaches the target voltage set by the target voltage setting unit,
The power supply device according to any one of appendices 1 to 5.

[Appendix 7]
The voltage controller is
A control signal generation unit that generates a control signal for controlling the power conversion unit such that a current according to an input target current setting signal is input or output at the first terminal or the second terminal;
A target current setting signal generation unit that generates the target current setting signal so that the voltage of the second terminal detected by the voltage detection unit approaches the target voltage set by the target voltage setting unit;
The target voltage setting unit sets, as the target voltage, the voltage of the second terminal that satisfies the relationship defined by the predetermined function with the current indicated by the target current setting signal.
The power supply device according to appendix 6.

DESCRIPTION OF SYMBOLS 1 ... AC system line, 2 ... Solar power generation device, 3 ... Storage battery, 4 ... Load, 5 ... Transformer, 7 ... DC bus, 10, 20, 30, 40 ... Power supply device, 11 ... Power conversion part, 12 ... Control part DESCRIPTION OF SYMBOLS 13 ... AC voltage detection part 14 ... AC current detection part 15 ... DC voltage detection part 120 ... Voltage control part 122 ... Target voltage setting part 1201 ... Target current setting signal generation part 1202 ... Control signal generation part .

Claims (5)

A power supply unit that can be operated by connecting a plurality of units in parallel,
A power converter that converts power input at the first terminal into power of a predetermined format and outputs the power from the second terminal;
A voltage detector for detecting the voltage of the second terminal;
The current or power input or output at the first terminal or the second terminal and the voltage at the second terminal detected by the voltage detector have a relationship defined by a predetermined function. A control unit for controlling the power conversion unit,
The predetermined function indicates that as the voltage detected by the voltage detector increases, the power transmitted from the first terminal to the second terminal continuously decreases, and the voltage detected by the voltage detector decreases. As the power is transmitted, the power transmitted from the first terminal to the second terminal continuously increases, so that the current input or output at the first terminal or the second terminal or the power and the voltage detection unit detects the current. Ri functions der which defines the relationship between the voltage of the second terminal being,
The power conversion unit can transmit power bidirectionally between the first terminal and the second terminal,
When the voltage detected by the voltage detection unit is lower than a predetermined first reference voltage, the control unit transmits power from the first terminal to the second terminal and is equal to the first reference voltage or When the detected voltage is higher than a second reference voltage higher than the first reference voltage, power is transmitted from the second terminal to the first terminal, and the detected voltage and the first reference voltage are transmitted. Alternatively, as the voltage difference from the second reference voltage increases, the power transmitted between the first terminal and the second terminal continuously increases according to the predetermined function, and as the voltage difference decreases, Controlling the power conversion unit so that the power transmitted between the first terminal and the second terminal continuously decreases according to the predetermined function;
Power supply. When the detected voltage is in a range not less than the first reference voltage and not more than the second reference voltage, the control unit is configured such that the power transmitted between the first terminal and the second terminal becomes zero. Controlling the power conversion unit,
The power supply device according to claim 1. The controller is
Changing a constant in the predetermined function according to an input control signal;
Or
According to an input control signal, one predetermined function is selected from a plurality of predetermined functions.
Or
According to the information indicating the definition of the function included in the input control signal, the predetermined function is changed to another function.
The power supply device according to claim 1 or 2. The controller is
Based on a signal indicating current or power input or output at the first terminal or the second terminal so as to satisfy the relationship defined by the predetermined function with the current or power indicated by the signal. A target voltage setting unit for setting a target voltage of the second terminal;
A voltage control unit that controls the power conversion unit so that the voltage of the second terminal detected by the voltage detection unit approaches the target voltage set by the target voltage setting unit,
The power supply device according to any one of claims 1 to 3. The voltage controller is
A control signal generation unit that generates a control signal for controlling the power conversion unit such that a current according to an input target current setting signal is input or output at the first terminal or the second terminal;
A target current setting signal generation unit that generates the target current setting signal so that the voltage of the second terminal detected by the voltage detection unit approaches the target voltage set by the target voltage setting unit;
The target voltage setting unit sets, as the target voltage, the voltage of the second terminal that satisfies the relationship defined by the predetermined function with the current indicated by the target current setting signal.
The power supply device according to claim 4.