JP3337635B2 - Power supply control device and system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for converting a DC power supply voltage having a large output fluctuation into an AC voltage, and a system therefor.

[0002]

2. Description of the Related Art Conventionally, a power supply control device for converting a DC power supply whose output voltage characteristic fluctuates greatly into an AC power supply has a converter for boosting the input voltage to stabilize it, and converts the converter output to an AC voltage. It consists of an inverter. In particular, a power supply control device for converting a DC voltage having a large fluctuation in output voltage characteristics into an AC voltage, such as a fuel cell, a photovoltaic cell, a storage battery, or an electric double layer capacitor, is described in, for example, JP-A-5-284654. I have.
This prior art is a boost converter that temporarily stores the energy of a DC power supply in a reactor by turning on and off a semiconductor switching element and then discharges the energy to charge a smoothing capacitor, thereby maintaining a substantially constant smoothing capacitor voltage, and an output of the boost converter. And an inverter circuit for converting a DC voltage into an AC voltage.

Hereinafter, a conventional power supply control device will be described.

FIG. 6 is a block diagram of a conventional power supply control device. However, the case where the number of phases is n = 2 is shown, and the same applies to n = 3. 6, when the semiconductor switching element 24 is turned on, the DC power supply 1 is short-circuited via the reactor 2, and energy due to the short-circuit current is stored in the reactor 2. When the semiconductor switching element 24 is turned off, the energy stored in the reactor 2 is stored in the smoothing capacitor 4 through the diode 3. The voltage across the smoothing capacitor 4 is detected by the DC voltage detecting means 6 so that the voltage across the smoothing capacitor 4 becomes a stabilized DC voltage.
To control the ON / OFF of the semiconductor switching element 24. DC is supplied to the inverter circuit 5 by the DC voltage of the smoothing capacitor 4. The inverter circuit 5 is PWM-controlled by an inverter control circuit 7 to obtain an AC waveform output.

[0005]

However, in the above-mentioned prior art, the output of the DC power supply 1 is made a stable DC constant voltage by the high frequency switching control of the semiconductor switching element 24, and this DC constant voltage is converted into an inverter circuit. 5, and is converted into an AC power by PWM control. In this process, the PWM for making the stabilized DC power supply
PWM control for AC conversion with control is required. For this reason, switching loss is increased, and improvement in efficiency is limited. Further, there is a problem that the control circuit configuration becomes complicated because two PWM controls are required.

The present invention has been made in consideration of the above-described conventional problems, and provides a power supply control device and a power supply control device capable of reducing switching loss, improving efficiency, simplifying a control circuit configuration and reducing costs. It is intended to provide.

[0007]

According to the first aspect of the present invention, there is provided a reactor connected to an output of a DC power supply, a first diode connected to the reactor, and a smoothing diode connected to the first diode. A capacitor, DC voltage detecting means for detecting the voltage of the smoothing capacitor, n second diodes having an anode connected to the reactor, and an n-phase bridge connected to the output of the smoothing capacitor and comprising a semiconductor switch element. An inverter circuit in which the cathodes of n second diodes are respectively connected to the respective midpoints of the n-phase bridge; and an n-phase bridge such that the output voltage waveform of the inverter circuit becomes a predetermined AC waveform. Phase switching control of the semiconductor switch element of the n-phase bridge based on the detection result of the DC voltage detection means. Te, superimposed on the phase switching control by PW
A power control device including an inverter control circuit that performs M control.

According to a third aspect of the present invention, there is provided a first reactor connected to an output of a DC power supply, a first diode connected to the first reactor, and a smoothing connected to the first diode. A capacitor, DC voltage detecting means for detecting the voltage of the smoothing capacitor, n second diodes having an anode connected to the reactor, and an n-phase bridge connected to the output of the smoothing capacitor and comprising a semiconductor switch element. An inverter circuit having cathodes of n second diodes connected to respective midpoints of the n-phase bridge; a second reactor for system-linking the output of the inverter circuit to a commercial power supply; Current detection means for detecting the output current of the circuit; AC voltage detection means for detecting the voltage of the commercial power supply; DC voltage detection means; current detection means; On the basis of the detection result of the detection means, the phase switching of the semiconductor switch element of the n-phase bridge is controlled so that the output voltage waveform of the inverter circuit becomes a predetermined AC waveform. Is a power supply control device including an inverter control circuit that performs PWM control by superimposing the PWM control on the phase switching control.

According to a fifth aspect of the present invention, there is provided a DC power supply having at least one of a fuel cell, a solar cell, a storage battery, and an electric double layer capacitor, and a DC power supply connected to the DC power supply. A power supply control system comprising the power supply control device according to any one of Items 1 to 4.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment. (First Embodiment) FIG. 1 is a block diagram of a power supply control device according to a first embodiment. Here, the number of phases n =
It is 2. In FIG. 1, the output of a DC power supply 1 is connected to the anodes of a first diode 3 and two second diodes 8 through a reactor 2. First
Is connected to a smoothing capacitor 4, and both ends of the smoothing capacitor 4 are connected to an inverter circuit 5 as a DC power supply. The cathodes of the two second diodes 8 are connected to each midpoint of the bridge of the inverter circuit 5. The output of the DC voltage detecting means 6 for detecting the voltage across the smoothing capacitor 4 is input to the inverter control circuit 7, and the drive signal is output to the semiconductor switching element of the inverter circuit 5.

FIG. 2 is a block diagram of the inverter control circuit 7. In FIG. 2, an error between a preset voltage value supplied from the DC voltage setting means 9 and a detection value of the DC voltage detecting means 6 is amplified by a DC voltage error amplifying means 10. The output of the waveform pattern generator 11 for determining the output voltage waveform of the inverter circuit 5 is multiplied by the output of the DC voltage error amplifier 10 by the multiplier 12. On the other hand, the output of the waveform pattern generating means 11 is input to the phase switching pulse generating means 13, where a pulse synchronized with the AC output is generated. Output of multiplying means 12 and phase switching pulse generating means 1
3 and the output of the triangular wave generating means 14 are input to a PWM pulse generating means 15 and generate a PWM signal from these signals. Outputs of the PWM pulse generating means 15 are connected to the semiconductor switching elements Qd1 and Qd connected to the DC negative electrode side of the bridge of the inverter circuit 5 through the drive circuit 16.
2 are driven to drive. The output of the phase switching pulse generating means 13 is connected to drive the semiconductor switching elements Qu1 and Qu2 connected to the DC positive side of the bridge of the inverter circuit 5 through the drive circuit 16.

Next, the operation of the power supply control device according to the first embodiment will be described with reference to the drawings.

Assume that a short-circuit current flows from the DC power supply 1 via the reactor 2 when the semiconductor switching element Qd2 on the DC negative side of the inverter circuit 5 is turned on, and energy is stored in the reactor 2. When turned off, the energy stored in the reactor 2 is charged in the smoothing capacitor 4. The voltage between both ends of the smoothing capacitor 4 is fed back to the inverter control circuit 7 by the DC voltage detecting means 6 and compared with the set value of the DC voltage setting means 9, and the DC voltage error amplifying means 1
The feedback amount is determined by 0. On the other hand, the waveform pattern generating means 11 generates a waveform pattern for determining the output voltage waveform of the inverter circuit 5, and the multiplication means 12 multiplies this waveform pattern by the feedback amount output from the DC voltage error amplifying means 10, and outputs A voltage command is obtained.

Further, a pulse for every half cycle is generated by the phase switching pulse generating means 13 from the AC signal output from the waveform pattern generating means 11, and the timing of driving each semiconductor switching element of the inverter circuit 5 is determined by the pulse. . The output of the triangular wave generating means 14, the output of the multiplying means 12, and the output of the phase switching pulse generating means 13 are input to the PWM pulse generating means 15, where they are converted into PWM signals. Of the negative side semiconductor switching element Qd2. As a result, the boosting operation and the inverter operation are performed simultaneously. Therefore, the in-phase positive polarity side semiconductor switching element Qu2 is turned off during this period, and the other-phase Qu-side semiconductor switching element Qu2 is turned off.
Reference numeral 1 denotes an output of the phase switching pulse generating means 13 which is driven through the drive circuit 16 so as to maintain the on state.

In addition, the PWM signal limits the PWM duty to an appropriate value of less than 100% in order to prevent a full-time short-circuit state within the PWM cycle period. FIG. 3 shows the operation waveform of each part. In FIG. 3, Qu1, Qu2, Qd1, Q
d2 is a drive waveform of each semiconductor switching element of the inverter circuit 5. Qu1 and Qu2 are responsible only for the phase switching of the AC output, and are PWM-controlled by Qd1 and Qd2, so that the boost converter operation and the inverter operation can be performed simultaneously. (Second Embodiment) FIG. 4 is a block diagram of a power supply control device according to a second embodiment, and FIG. 5 is a block diagram of the inverter control circuit. Hereinafter, description of the same components as those in FIGS. 1 and 2 will be omitted. In FIG. 4, the output of the inverter circuit 5 is system-connected to a commercial power supply 20 via a reactor 17 that is a second reactor. The output current of the inverter circuit 5 is detected by the current detecting means 18, and the voltage of the commercial power supply 20 is detected by the AC voltage detecting means 19 and input to the inverter control circuit 7.
Here, the reactor 2 is the first reactor.

In FIG. 5, the voltage polarity and phase are detected by the voltage phase detecting means 21 from the output of the AC voltage detecting means 19, and a sine wave synchronized with the commercial power is generated by the sine wave generating means 22 from the detection signal. DC voltage error amplifier 10
Is multiplied by the output of the sine wave generating means 22 by the multiplying means 12 and converted into a command for the output current of the inverter circuit 5. An error between the output of the current detecting means 18 for detecting the output current of the inverter circuit 5 and the output of the multiplying means 12 is amplified by the AC current error amplifying means 23, and the output is output to the phase switching pulse generating means 13 and the PWM pulse generating means 15 Is input to

The phase switching pulse generating means 13 supplies the phase switching pulse to the inverter circuit 5 through the drive circuit 16,
The PWM pulse generating means 15 generates a PWM pulse from the output of the triangular wave generating means 14, the output of the phase switching pulse generating means 13 and the output of the AC current error amplifying means 23, and outputs the generated PWM pulse through the drive circuit 16 to the inverter circuit. 5

Next, the operation of the power supply control device according to the second embodiment will be described with reference to the drawings.

In the present embodiment, the current minor loop is provided because the output of the inverter circuit 5 needs to operate as a current source when connected to a commercial power supply system. Multiplication means 1 for obtaining a product of a reference sine wave synchronized with commercial power supply 20 output from sine wave generation means 22 and an error feedback amount of the DC voltage output from DC voltage error amplification means 10
The output of (2) can be a command value of the inverter output current. A current minor loop can be formed by taking the error current between the output of the multiplication means 12 and the actual output of the AC current detection means 18.

In this embodiment, similarly to the first embodiment, the semiconductor switching element Qu on the positive polarity side of the bridge circuit is generated by the output signal of the phase switching pulse generating means 13.
1 and Qu2, and controls the semiconductor switching element Qd on the negative polarity side by the output signal of the PWM pulse generating means 15.
1 and Qd2. Therefore, the switching elements Qu1 and Qu2 take charge of only the phase switching of the AC output,
Since the PWM control is performed by the switching elements Qd1 and Qd2, the boost converter operation and the inverter operation can be performed simultaneously. (Third Embodiment) In a third embodiment, there is provided a power supply control system including the power supply control device according to any one of the above-described embodiments and a DC power supply connected to the power supply control device. Is what you do. Here, as a DC power supply,
Any of a fuel cell, a solar cell, a storage battery, and an electric double layer capacitor, or a combination of two or more of these can be used. Although the output of these batteries or accumulators has a drooping characteristic, the voltage applied to the inverter is stabilized by the step-up converter operation against fluctuations in the output voltage, so that the AC output of the inverter can be efficiently stabilized. .

As described above, according to the present invention, the following effects can be obtained. In the power supply control device according to the first embodiment, since a dedicated semiconductor switching element is not required to obtain the DC boost stabilization voltage, the semiconductor switching element of the inverter circuit can also be used, so that a large switching can be achieved. Loss can be reduced. at the same time,
Since a control circuit for PWM control is not required, cost can be reduced. Furthermore, since the semiconductor switching element on the positive electrode side of the bridge of the inverter circuit is only energized and non-switching is performed, switching loss can be reduced and efficiency can be greatly improved.

In the power supply control device of the second embodiment, by adding a current minor loop, the inverter can be operated as a current source through the system reactor, so that the system interconnection can be performed with high efficiency.

In the power supply control system according to the third embodiment, any one of a fuel cell, a photovoltaic cell, a storage battery, and an electric double layer capacitor having a large output fluctuation, or any of them is used as a DC power supply of the power supply control device. A stable AC output can be obtained with high efficiency by using a combination of two or more of the above.

In the above embodiment, the number of phases is n = 2. However, the number of phases is not limited to this and may be three. In that case, the number of the second diodes may be connected in accordance with the number of each phase (the number of midpoints of the bridge).

Further, the configuration of the inverter control circuit shown in FIGS. 2 and 5 in the above embodiment is an example, and if the configuration is such that the boost converter operation and the inverter operation can be performed simultaneously as described above, The configuration may be different from that described above.

[0026]

As apparent from the above description, the present invention can reduce the switching loss and improve the efficiency,
There is an advantage that the cost can be reduced by simplifying the control circuit configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a power supply control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an inverter control circuit according to the first embodiment.

FIG. 3 is a drive waveform diagram of the inverter circuit according to the first embodiment.

FIG. 4 is a block diagram illustrating a power supply control device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing an inverter control circuit according to the second embodiment.

FIG. 6 is a block diagram showing a conventional power supply control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DC power supply 2, 17 reactor 3 first diode 4 smoothing capacitor 5 inverter circuit 6 DC voltage detecting means 7 inverter control circuit 8 second diode 9 DC voltage setting means 10 DC voltage error amplifying means 11 waveform pattern generating means 12 multiplication Means 13 Phase switching pulse generating means 14 Triangular wave generating means 15 PWM pulse generating means 16 Drive circuit 18 Current detecting means 19 AC voltage detecting means 20 Commercial power supply 21 Voltage phase detecting means 22 Sine wave generating means 23 AC current error amplifying means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-284654 (JP, A) JP-A-9-131069 (JP, A) JP-A-9-47033 (JP, A) JP-A 8- 237884 (JP, A) JP-A-6-343271 (JP, A) JP-A-10-271833 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/42-7 / 98 H02J 3/38 H02J 9/06 504

Claims (5)

(57) [Claims] 1. A reactor connected to an output of a DC power supply, a first diode connected to the reactor,
A smoothing capacitor connected to the first diode;
DC voltage detecting means for detecting the voltage of the smoothing capacitor; and n second second electrodes having anodes connected to the reactor.
And an n-phase bridge connected to the output of the smoothing capacitor and comprising a semiconductor switch element.
An inverter circuit in which the cathodes of the n second diodes are connected to respective midpoints of the n-phase bridge; and an inverter circuit of the n-phase bridge so that the output voltage waveform of the inverter circuit has a predetermined AC waveform. An inverter control circuit that performs phase switching control of a semiconductor switching element and performs PWM control by superimposing the phase switching control on the semiconductor switching element on the negative side of the n-phase bridge based on the detection result of the DC voltage detection means; And a power supply control device. 2. An inverter control circuit comprising: a DC voltage error amplifying means for amplifying an error between a preset DC voltage setting means and a voltage value detected by the DC voltage detecting means; and an output voltage of the inverter circuit. Waveform pattern generating means for determining a waveform, multiplying means for multiplying the output of the DC voltage error amplifying means by the output of the waveform pattern generating means, and generating a phase switching pulse from the output of the waveform pattern generating means A phase-switching pulse generator, a triangular-wave generator, a PWM for generating a PWM signal based on an output of the multiplier and an output of the phase-switching pulse generator.
A semiconductor switch element connected to a positive electrode side of an n-phase bridge of the inverter circuit, the semiconductor switch element being controlled by the phase switching pulse generating means, and a negative electrode of an n-phase bridge of the inverter circuit. The power supply control device according to claim 1, wherein the semiconductor switch element connected to the side is controlled by the PWM pulse generation means. 3. A first reactor connected to an output of a DC power supply, a first diode connected to the first reactor, a smoothing capacitor connected to the first diode, and the smoothing capacitor DC voltage detecting means for detecting the voltage of the first and second n diodes connected to the anode of the reactor, and an n-phase bridge which is connected to the output of the smoothing capacitor and includes a semiconductor switch element. At each midpoint of the n-phase bridge, the n second
An inverter circuit to which a cathode of each of the diodes is connected, a second reactor for system-linking the output of the inverter circuit to a commercial power supply, current detecting means for detecting an output current of the inverter circuit, And an output voltage waveform of the inverter circuit based on detection results of the DC voltage detection means, the current detection means, and the AC voltage detection means, and a predetermined AC waveform. An inverter control circuit that performs a phase switching control of the semiconductor switching element of the n-phase bridge, and performs a PWM control for the semiconductor switching element on the negative electrode side of the n-phase bridge by superimposing the phase switching control. Characteristic power supply control device. 4. An inverter control circuit comprising: a DC voltage error amplifying means for amplifying an error between a preset DC voltage setting means and a voltage value detected by the DC voltage detecting means; Based on the output, a voltage phase detecting means for performing phase synchronization, and a sine wave generating means for generating a sine wave synchronized with a commercial power supply from the voltage phase detecting means,
Multiplying means for multiplying an output of the sine wave generating means and an output of the DC voltage error amplifying means; an AC current error amplifying means for amplifying an error between an output of the multiplying means and an output of the current detecting means; Phase switching pulse generating means for generating a phase switching pulse from the output of the AC current error amplifying means, PWM for generating a PWM signal based on the output of the triangular wave generating means, the output of the multiplying means and the output of the phase switching pulse generating means
A semiconductor switch element connected to a positive electrode side of an n-phase bridge of the inverter circuit, the semiconductor switch element being controlled by the phase switching pulse generating means, and a negative electrode of an n-phase bridge of the inverter circuit. The power supply control device according to claim 3, wherein the semiconductor switch element connected to the side is controlled by the PWM pulse generating means. 5. A DC power supply having at least one of a fuel cell, a photovoltaic cell, a storage battery, and an electric double layer capacitor, and a DC power supply connected to the DC power supply. A power supply control system comprising any one of the power supply control devices.