JP6692168B2 - Power storage device having UPS function and method of controlling power storage device having UPS function - Google Patents

Description

  The present invention relates to a power storage device having a UPS function and a method for controlling a power storage device having a UPS function.

  In a power storage device having a UPS (Uninterruptible Power Supply) function, a constant inverter system is adopted in order to stably supply AC power to various loads.

  The power storage device includes a converter circuit that converts an AC voltage supplied from a commercial power source into a DC voltage, an inverter circuit that converts a DC voltage input from the converter circuit into an AC voltage, a storage battery, and a DC voltage boosted by the storage battery. A boost converter circuit that outputs the output voltage to the inverter circuit and a boost control unit that performs feedback control so that the output voltage of the boost converter circuit becomes a predetermined voltage are provided.

  As the converter circuit, a PFC (Power Factor Correction) circuit for boosting while improving the power factor, a converter circuit for boosting a DC voltage rectified by a rectifying circuit, and the like are used.

  Then, when the commercial power source fails, the boost converter circuit activates the boost converter circuit, boosts the output voltage of the storage battery to a predetermined voltage, and inputs the boosted voltage to the inverter circuit.

  Patent Document 1 discloses a step-up DC-DC converter capable of optimally and efficiently maintaining operation in a discontinuous mode without impairing load characteristics and responsiveness.

  The step-up DC-DC converter includes an inductance element, a switching element connected in series with the inductance element via a node between a DC voltage input input terminal and a reference potential terminal, a node and an output terminal. A rectifying element connected between the output terminal and the reference potential terminal, an output capacitor connected between the output terminal and the reference potential terminal, and each cycle defined by the main clock of a constant frequency is divided into two variable ON and OFF periods. However, a switching control circuit that turns on the switching element during the on period and turns off the switching element during the off period, and whether or not current is still flowing from the inductance element to the output capacitor at the end of each cycle. The current monitoring circuit to be monitored and the ON period for each cycle are limited to the specified upper limit or less, and the monitoring result of the current monitoring circuit is adjusted. Te is configured to include an on period limit control circuit for variably controlling the upper limit of the ON period in the next cycle.

  In Patent Document 1, the transfer function in the current discontinuous mode can be approximated as a first-order pole system and stable operation can be performed, but the transfer function in the current continuous mode becomes a second-order pole system, and the zero point of the RHP (right half plane). It is described that since the compensation is complicated and difficult because it has, the stable operation and the simplification of the circuit configuration can be achieved by exclusively configuring to operate in the current discontinuous mode.

JP, 2009-201247, A

  By the way, in the above-described power storage device having the UPS function, when an AC voltage of a predetermined level is input from a commercial power source, a predetermined DC voltage boosted via a converter circuit such as a PFC circuit (for example, DC150V). Is input to the inverter circuit, and a predetermined AC voltage (for example, AC 100 V) generated by the inverter circuit is supplied to the load.

  Then, when the commercial power supply fails, the DC voltage of the storage battery is boosted to a predetermined DC voltage (for example, DC150V) by the boost converter circuit and then input to the inverter circuit.

  Further, a large-capacity electrolytic capacitor is provided at the input stage of the inverter circuit so that a stable AC voltage can be output from the inverter circuit even if the commercial power supply fluctuates in voltage.

  When a commercial power supply connected to such a power storage device having a UPS function fails, feedback control is performed by the boost control unit so that the output voltage of the boost converter circuit becomes a desired voltage (for example, DC150V), specifically, a predetermined control. The PWM control is performed at the duty ratio set by the PI control of the gain. Then, the gain of the feedback control is usually set with reference to the case where the load connected to the inverter is heavy and the operation is performed in the continuous current mode.

  However, sufficient charge remains in the above-mentioned electrolytic capacitor immediately after the occurrence of a power failure in the commercial power supply, and the boost converter circuit is in a state similar to the no-load state, so in the current discontinuous mode with a small output current. However, there has been a problem that the responsiveness is lowered and stable control becomes difficult.

  Therefore, if the peak value of the current flowing through the inductor is reduced and the control is performed in the continuous current mode at all times, the value of the inductor needs to be increased and the circuit component becomes large.

  In view of the above-mentioned problems, an object of the present invention is to provide a power storage device and a UPS function having a UPS function capable of improving a decrease in responsiveness when controlled in a discontinuous current mode while using an inductor having a small value. Another object is to provide a method for controlling a power storage device having the above.

In order to achieve the above-mentioned object, the first characteristic configuration of the power storage device having the UPS function according to the present invention is, as described in claim 1 of the document of the claims, an AC voltage supplied from a commercial power source to a DC voltage. AC / DC converter circuit for converting to voltage, inverter circuit for converting DC voltage input from the AC / DC converter circuit to AC voltage, storage battery, and boosting DC voltage of the storage battery to output to the inverter circuit A booster converter circuit, and a booster control unit that performs feedback control so that the output voltage of the booster converter circuit becomes a predetermined voltage. The converter circuit can be switched between continuous current mode control and current discontinuous mode control. Is set to de-value gain is different of the feedback control in the current discontinuous mode, the control in the current discontinuous mode to detect a power failure of the commercial power supply to start the step-up converter circuit, said from subsequent storage battery It is configured to switch to the continuous current mode based on the input current to the boost converter circuit .

  When the load is heavy, the current continuous mode is controlled, and when the load is light, the current discontinuous mode is controlled. Since the gain when controlled in the continuous current mode and the gain when controlled in the discontinuous current mode are set to different values, it is possible to control with appropriate response performance in each mode.

Then, according to the above configuration, when the commercial power supply fails, the current is rapidly boosted in the current discontinuous mode, and then, when the voltage becomes close to the predetermined target input voltage set in the inverter circuit, for example, the current continuous mode is switched. Since the feedback control is performed in the current discontinuous mode with a gain different from that in the current continuous mode, the responsiveness does not decrease even when a large capacity capacitor is provided in the input stage of the inverter circuit. When the input current rises above a predetermined threshold current during the control in the current discontinuous mode, it is determined that the load becomes heavy, and the control is switched to the current continuous mode with a gain different from that in the current discontinuous mode.

A first characteristic configuration of a method for controlling a power storage device having a UPS function according to the present invention is, as described in claim 4 , a converter circuit for converting an AC voltage supplied from a commercial power source into a DC voltage, and the converter circuit. An inverter circuit that converts a DC voltage input from the AC voltage into an AC voltage, a storage battery, a boost converter circuit that boosts the DC voltage of the storage battery and outputs the boosted DC voltage to the inverter circuit, and an output voltage of the boost converter circuit is a predetermined voltage. A method of controlling a power storage device having a UPS function, comprising: a boost control unit that performs feedback control so that the boost converter circuit is started when a power failure of the commercial power supply is detected, and a predetermined current mode is set. performs feedback control by the gain, and from then the storage battery based on the input current to the boost converter circuit Lies in performing feedback control by different gains is switched to flow discontinuous mode.

  As described above, according to the present invention, a power storage device having a UPS function and a UPS function capable of improving a decrease in responsiveness when controlled in a current discontinuous mode are provided while using an inductor having a small value. It has become possible to provide a method for controlling a power storage device.

Configuration diagram of a power storage device having a UPS function according to the present invention Control unit and boost converter circuit diagram according to the present invention Control signal waveform and circuit current waveform diagram by conventional control method Control signal waveform and circuit current waveform diagram according to the control method of the present invention Comparison diagram of output current and inverter input voltage between the conventional control method and the control method of the present invention Flow chart of the control method according to the present invention Control signal waveform and circuit current waveform diagram when the gain is changed in the current continuous mode and the current discontinuous mode by the control according to the present invention

  An example of a power storage device having a UPS function and a control method of a power storage device having a UPS function according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a power storage device 1 having a UPS function according to the present invention.
The power storage device 1 having the UPS function includes an AC / DC converter circuit 20 that converts an AC voltage supplied from a commercial power supply 10 into a DC voltage, and an inverter that converts a DC voltage input from the AC / DC converter circuit 20 into an AC voltage. The circuit 30, the storage battery 40, the boost converter circuit 50 that boosts the DC voltage of the storage battery 40 and outputs the boosted DC voltage to the inverter circuit 30, and the boost control unit 60 that performs feedback control so that the output voltage of the boost converter circuit 50 becomes a predetermined voltage. It is configured with.

  In the electricity storage device 1 having the USP function of the inverter system at all times, a large-capacity electrolytic capacitor is mounted on the input portion B of the inverter circuit 30 in order to maintain the voltage of the AC output 15.

  The boost control unit 60 is configured to be able to switch between controlling the boost converter circuit 50 in the current continuous mode or the current discontinuous mode, and sets the gain of feedback control in the current continuous mode and the current discontinuous mode. It is set to a different value.

  When the load is heavy, the current continuous mode is controlled, and when the load is light, the current discontinuous mode is controlled. Since the gain when controlled in the continuous current mode and the gain when controlled in the discontinuous current mode are set to different values, it is possible to control with appropriate response performance in each mode.

  Here, the operation when the commercial power supply 10 fails will be described. FIG. 5 is a waveform diagram of the input voltage to the inverter circuit 10 and the output current of the boost converter circuit 50 according to the conventional control when the commercial power supply stops due to a power failure, and the input voltage to the inverter circuit 10 according to the present invention. 5B is a waveform diagram of the output current of the boost converter circuit 50.

  Conventionally, when the commercial power supply 10 is stopped, since a large-capacity electrolytic capacitor is mounted on the input section B of the inverter circuit 30, the load seen from the output side of the boost converter circuit 50 is light and the current discontinuous mode is used. The current was supplied from the storage battery 40 while being controlled. Therefore, although the amount of electric charge accumulated in the large-capacity electrolytic capacitor is small, the current consumed in the inverter circuit 10 does not change, and therefore the input voltage of the inverter circuit 30 changes until the output current of the boost converter switches to the current continuous mode. However, there is a problem that the voltage cannot be temporarily dropped and the voltage cannot be stably supplied to the inverter circuit 30.

  According to the present invention, when the commercial power supply 10 is stopped, a large-capacity electrolytic capacitor is mounted on the input section B of the inverter circuit 30, so that the load seen from the output side of the boost converter circuit 50 is light and the current discontinuity is low. Control is started in the mode. However, the boost control unit 60 monitors the change in the output voltage of the boost converter circuit 50, and immediately after the power failure occurs, the PI control unit mounted inside the control unit 60 adjusts the gain to enter the current continuous mode. It is configured to switch. The current flowing from the boost converter circuit 50 is increased, a current commensurate with the current consumed by the inverter circuit 10 is supplied from the boost converter circuit 50 to the inverter circuit 30, and the current continuous mode is gradually switched. Therefore, even if a large load is applied to the inverter circuit 30 and current is consumed, the input voltage of the inverter circuit 10 will not drop.

  When the commercial power supply 10 has a power failure, the current is rapidly boosted in the continuous current mode, and then, for example, when it approaches the predetermined target input voltage set in the inverter circuit 30, the current discontinuous mode is switched. In the discontinuous current mode, feedback control is performed with a gain different from that in the continuous current mode, so that even if an electrolytic capacitor having a large capacity is provided in the input stage of the inverter circuit 30, the responsiveness does not deteriorate. ..

The above control method will be described from the signal waveform of each element.
FIG. 3 is a circuit diagram of a conventional control method, a current I (L1) flowing in an inductor L1 of the boost converter circuit 50, a gate-source voltage VGS which is a switching signal of a switching element Tr1 of the boost converter circuit 50, and a control unit. The PWM signal voltage is shown.

  When a power failure occurs, the voltage Vo across the electrolytic capacitor C2 in FIG. 3 changes. Since the capacity of the electrolytic capacitor C2 is large, the change in the voltage Vo at the beginning of the power failure is not large. However, the step-up control unit starts the PWM operation shown in FIG. 3 (d) in response to the change in the voltage Vo at the beginning of the power failure, and initially the PWM operation voltage in FIG. 3 (d) is at the position (n) in FIG. 3 (c). A gate-source voltage VGS, which is a switching signal shown in FIG. Along with this, the current I (L1) in the current discontinuous mode flows through the inductor L1, and electromagnetic energy is accumulated.

  On the other hand, in the inverter 30, the voltage Vo was initially output across the load R1, but the voltage output from the storage battery 40 via the boost converter circuit 50 due to a power failure is due to the current discontinuous mode. During the Ioff period, no current flows, and a current sufficient to cover the power consumed by the load R1 of the inverter 30 cannot be supplied, resulting in a large decrease in the output voltage Vo of the boost converter circuit 50.

  When the decrease of the output voltage Vo becomes large, the change of the output voltage Vo is detected for the first time, and the PWM control voltage of FIG. 3 (d) changes to the position shown in (m) in the step-up control unit, as shown in FIG. 3 (b). A gate-source voltage VGS, which is a switching signal, is generated, and along with this, a current I (L1) in the current continuous mode flows through the inductor L1, while electromagnetic energy is accumulated.

  When the current I (L1) in the continuous current mode begins to flow, a current sufficient to cover the power consumed by the load R1 of the inverter 30 is supplied, and as a result, the output voltage Vo of the boost converter circuit 50 returns to the voltage before the power failure.

  During a power failure in the above series of operations, the output voltage Vo of the boost converter circuit 50 temporarily fluctuates until the current discontinuous mode is switched to the current continuous mode.

  Next, FIG. 4 shows a circuit diagram according to the control method of the present invention, a current I (L1) flowing in the inductor L1 of the boost converter circuit 50, a gate-source voltage VGS which is a switching signal of the switching element Tr1 of the boost converter circuit 50, and The PWM signal voltage of the boost controller 60 is shown.

  When a power failure or an input voltage fluctuation occurs, the voltage Vo across the electrolytic capacitor C2 in FIG. 4 changes. Since the capacity of the electrolytic capacitor C2 is large, the change in the output voltage Vo of the boost converter circuit 50 at the beginning of the power failure is not large. However, the boost control unit starts the PWM operation shown in FIG. 4C in response to the change in the output voltage Vo of the boost converter circuit 50 at the beginning of the power failure. In this case, unlike the conventional control method, the gain by PI control is multiplied according to the amount of change in the output voltage Vo of the boost converter circuit 50, and the PWM operation of FIG. A gate-source voltage VGS, which is a switching signal shown in FIG. 4A, is generated, and accordingly, the inductor L1 transits from the current discontinuous mode to the current continuous mode. The current I (L1) gradually increases in the inductor L1 and electromagnetic energy is accumulated.

  When the current I (L1) in the continuous current mode starts to flow, a current sufficient to cover the power consumed by the load R1 of the inverter 30 is supplied, and as a result, the output voltage Vo of the boost converter circuit 50 decreases the voltage before the power failure. Continue to maintain without.

  FIG. 2 shows the configuration of the boost control unit 60 according to the voltage control method of the present invention described above. The output voltage Vo of the step-up converter circuit 50 is resistance-divided to take in its voltage change as an input signal, PI control is performed by a control circuit or the like, the gains Kp and Ki are multiplied by the voltage change amount, etc., and the result is a PWM circuit. Is input. The PWM circuit inputs a pulse signal for operating the switching element to the gate electrode of the switching element via the drive circuit. The output voltage Vo of the boost converter circuit 50 is controlled by the pulse signal input to this switching element.

  A microcomputer may be used as the control circuit. In this case, the output voltage Vo of the boost converter circuit 50 is resistance-divided to capture the voltage change as an input signal, and then the input signal is A / D converted to be used as an input of a PI control program previously incorporated in the microcomputer. give. The same control can be performed by D / A converting the result calculated by the PI control program and inputting it to the PWM circuit.

  Further, while the storage battery 40 is operating, the boost control unit 60 controls the boost converter circuit 50 in the current discontinuous mode or the current continuous mode based on the input current from the storage battery 40 to the boost converter circuit 50. It is also configured to switch between doing and not.

  Whether the load is light or heavy can be determined based on the input current from the storage battery 40 to the boost converter circuit 50. For example, when the input current is lower than a predetermined threshold current while being controlled in the continuous current mode, it is determined that the load becomes light. Then, the control is switched to the control in the discontinuous current mode with a gain different from that in the continuous current mode. Also, for example, when the current is controlled in the current discontinuous mode, it is determined that the load becomes heavy when the input current rises above a predetermined threshold current, and the control is switched to the current continuous mode with a gain different from that in the current discontinuous mode. .. In either case, stable responsiveness can be realized.

  Furthermore, the boost control unit 60 is configured to switch to the current discontinuous mode when a predetermined time has elapsed after starting the boost converter circuit 50 in the current continuous mode.

  After the boost converter circuit 50 is started in the continuous current mode, the time to be boosted to the vicinity of the predetermined target input voltage set in the inverter circuit 30 is almost constant. You may switch to.

  A control method of the power storage device having the UPS function according to the present invention is shown in the flowchart of FIG. First, the boost controller 60 constantly monitors for power failure. If a power failure can be detected (S1), a change in the output voltage is detected and the operation of the boost converter circuit 50 is started in the discontinuous current mode (S2). The gain is adjusted by the PI control (S3) to switch to the current continuous mode (S4) to monitor the output voltage, the output current of the storage battery 40 or the operation time of the storage battery 40 to determine whether to switch to the current discontinuous mode. (S5). If the output voltage becomes stable with respect to the load, the current discontinuous mode is switched to (S6). If the output voltage is not stable, the gain is readjusted to operate in the continuous current mode (S4). Even when the output voltage is stable with respect to the load, the gain is adjusted in preparation for the load variation (S7), and the storage battery is operated until the power failure is restored.

  Furthermore, not only during a power failure, but also when commercial power is supplied, the current continuous mode and the current discontinuous mode are switched as appropriate to optimize the output for each mode even for the size of the connected load. The gain can also be controlled in each current mode so that a voltage can be obtained.

  As an example, as shown in FIG. 7, when the current continuous mode and the current discontinuous mode have different gains, the current I (L1) flowing through the inductor also changes. For example, when the gain is g1 in the discontinuous current mode, the time during which no current flows decreases with the passage of time, and a constant output voltage can be maintained even when the load increases. Further, it is understood that when the gain is g2 in the continuous current mode, the current I (L1) flowing in the inductor increases with the passage of time, and in this case as well, a constant output voltage can be maintained even when the load becomes large.

  As the switching elements provided in the boost converter circuit 50 and the inverter circuit 30, in addition to the MOS-FET and the bipolar transistor, it is also possible to use an IGBT or the like which is a power semiconductor having an MOS input portion and a bipolar output portion.

  As another embodiment, unlike the boost converter circuit 50 described above, a circuit configuration in which the buck-boost converter circuit is connected to the storage battery 40 from the commercial power supply 10 is conceivable. This is used for the purpose of charging the storage battery 40 using the step-up / down converter circuit through the commercial power source 10 when the commercial power source is not used much at night.

  In each of the above-described embodiments, only a specific example of a power storage device having a UPS function according to the present invention has been described, and the scope of the present invention is not limited by the description, and the specific configuration of each part is the present invention. Needless to say, it is possible to appropriately change the design within a range in which the above-mentioned action and effect are exhibited.

1: Power storage device 10 having a UPS function: Commercial power supply 15: AC output 20: AC / DC converter circuit 30: Inverter circuit 40: Power storage device 50: Boost converter 60: Boost control unit

Claims (2)

An AC / DC converter circuit for converting an AC voltage supplied from a commercial power source into a DC voltage;
An inverter circuit for converting a DC voltage input from the AC / DC converter circuit into an AC voltage;
Storage battery,
A boost converter circuit for boosting the DC voltage of the storage battery and outputting it to the inverter circuit;
A boost control unit that performs feedback control so that the output voltage of the boost converter circuit becomes a predetermined voltage;
A power storage device having a UPS function, comprising:
The boost control unit is configured to be able to switch between controlling the boost converter circuit in a continuous current mode or in a discontinuous current mode, and also provides a gain of the feedback control in a continuous current mode and a discontinuous current mode. Are set to different values ,
When a power failure of the commercial power source is detected, the boost converter circuit is activated to control in the current discontinuous mode, and then switched to the current continuous mode based on the input current from the storage battery to the boost converter circuit . A power storage device having a UPS function characterized by the above. An AC / DC converter circuit for converting an AC voltage supplied from a commercial power source into a DC voltage;
An inverter circuit for converting a DC voltage input from the AC / DC converter circuit into an AC voltage;
Storage battery,
A boost converter circuit for boosting the DC voltage of the storage battery and outputting it to the inverter circuit;
A boost control unit that performs feedback control so that the output voltage of the boost converter circuit becomes a predetermined voltage;
A method of controlling a power storage device having a UPS function, comprising:
When the power failure of the commercial power source is detected, the boost converter circuit is started to perform feedback control with a predetermined gain in the current discontinuous mode, and then switched to the current continuous mode based on the input current from the storage battery to the boost converter circuit. A method of controlling a power storage device having a UPS function, which comprises performing feedback control with different gains.

Images