JP2010172105A - Power conversion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress fluctuation of an input-side DC intermediate voltage of an inverter, and to sufficiently store power in a power storage means and control the DC intermediate voltage. <P>SOLUTION: During non-power failure time, a storage voltage deviation ΔBAT being a deviation between a real storage voltage BAT of a storage cell 8 and a storage voltage command value Sbat, and a DC intermediate voltage deviation ΔDC being a deviation between a real DC intermediate voltage DC of a DC intermediate circuit 3 and a control DC intermediate voltage command value SAdc are operated. Each of these deviations is used as a deviation signal δV and a step-up/down control signal with respect to a step-up/down chopper 7 is generated based on the deviation signal δV. A step-up operation or a step-down operation is performed by giving priority to either the real storage voltage BAT or real DC intermediate voltage DC which has a larger lack amount to each target value. When real DC intermediate voltage DC is less than the control DC intermediate voltage command value SAdc, the storage voltage deviation ΔBAT is restricted to an upper-limit value Hb equivalent to zero, and DC intermediate voltage is preferentially controlled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power converter that charges power storage means with DC power obtained by rectifying an AC input, and supplies power to a load using DC power obtained by rectification or stored energy of the power storage means.

For example, an uninterruptible power supply as shown in FIG. 3 has been proposed as an uninterruptible power supply that supplies power to a load without an uninterruptible power (see, for example, Patent Document 1).
In FIG. 3, 1 is an AC power source, 2 is a rectifier that converts AC power from the AC power source 1 into DC power, 3 is a DC intermediate circuit connected to the DC output of the rectifier 2, and 4 is a voltage of the DC intermediate circuit 3. DC capacitor 5 for smoothing the DC, 5 is an inverter for converting DC power from the DC intermediate circuit 3 into AC power, and 6 is a load.

Reference numeral 7 denotes a step-up / down chopper that charges the storage battery 8 from the DC intermediate circuit 3 and discharges from the storage battery 8 to the DC intermediate circuit 3.
The step-up / step-down chopper 7 is anti-parallel to each of the first transistor 7a and the second transistor 7b, and the first transistor 7a and the second transistor 7b, each composed of an IGBT (insulated gate bipolar transistor) connected in series. The freewheeling diodes 7c and 7d connected to each other, the chopper reactor 7e having one end connected to the connection point of the first transistor 7a and the second transistor 7b, the other end of the chopper reactor 7e, and the emitter side of the second transistor 7b And the smoothing capacitor 7f connected in parallel with the second transistor 7b and the storage battery 8 are provided.

Both ends of the first transistor 7 a and the second transistor 7 b connected in series are connected in parallel between the DC capacitor 4 and the inverter 5.
Reference numeral 9 designates a chopper control that causes the step-up / step-down chopper 7 to operate as a step-down chopper to charge the storage battery 8 and also causes the step-up / step-down chopper 7 to operate as a step-up chopper to supply DC power to the DC intermediate circuit 3 using the storage battery 8 as a DC power source. The circuit is shown.

  The chopper control circuit 9 includes a first gate drive circuit (GDU) 9a for driving the first transistor 7a, a second gate drive circuit (GDU) 9b for driving the second transistor 7b, a first gate drive circuit 9a, and a second gate drive circuit 9a. A pulse generation circuit 9c that outputs a gate pulse to the gate drive circuit 9b is provided. The first gate driving circuit 9a and the second gate driving circuit 9b supply a gate driving signal to the first transistor 7a and the second transistor 7b according to the gate pulse from the pulse generation circuit 9c, and the first gate driving circuit 9b according to the gate pulse. The transistor 7a and the second transistor 7b are turned on / off.

  Further, 10 is a voltage sensor that detects an input voltage from the AC power supply 1, 11 is a power failure detector that detects that the AC power source 1 is in a power failure state based on the detection result of the voltage sensor 10, and 12 is a DC intermediate circuit 3. A voltage sensor for detecting the DC voltage of the battery, and 13 is a voltage sensor for detecting the storage voltage of the storage battery 8. The detection results of the power failure detector 11 and the voltage sensors 12 and 13 are input to the pulse generation circuit 9c. Then, the pulse generation circuit 9c generates gate pulses to the first gate drive circuit 9a and the second gate drive circuit 9b based on these detection results.

In such a configuration, the rectifier 2 normally converts AC power from the AC power source 1 into DC power and outputs the DC power to the DC intermediate circuit 3. The inverter 5 converts the DC power from the DC intermediate circuit 3 into predetermined AC power and supplies the converted AC power to the load 6.
At this time, no power failure is detected in the power failure detector 11 that detects the power failure of the AC power source 1 based on the detection result of the voltage sensor 10 that detects the input voltage from the AC power source 1 and is detected by the voltage sensor 12. When the direct current intermediate voltage of the direct current intermediate circuit 3 is higher than the direct current intermediate voltage command value, the pulse generation circuit 9c applies a gate pulse to the first gate drive circuit 9a so that the first transistor 7a repeats the on / off operation. Output.

  That is, when the pulse generation circuit 9c operates the first gate drive circuit 9a and turns on the first transistor 7a by the gate drive signal from the first gate drive circuit 9a, the DC intermediate circuit 3, the first transistor 7a, the chopper A charging current flows to the storage battery 8 through the path of the reactor 7 e, the storage battery 8, and the DC intermediate circuit 3. Next, when the first transistor 7a is turned off, the current flowing through the chopper reactor 7e is circulated through the path of the chopper reactor 7e, the storage battery 8, the second freewheel diode 7d, and the chopper reactor 7e, and the DC intermediate circuit 3 is DC-converted. The storage battery 8 is charged by operating as a well-known step-down chopper including a first transistor 7a, a chopper reactor 7e, and a second freewheeling diode 7d.

  Further, for example, the DC intermediate circuit detected by the voltage sensor 12 is in a state where the sum of the power consumption of the load 6 and the power stored in the storage battery 8 exceeds the threshold value of the power supplied from the AC power supply 1 to be limited. When the DC intermediate voltage 3 is lower than the DC intermediate voltage command value, the pulse generation circuit 9c first outputs a gate pulse to the first gate drive circuit 9a so as to stop charging the storage battery 8. If there is still a deviation even after the charging of the storage battery 8 is stopped, that is, when the charging of the storage battery 8 is stopped, the voltage of the DC intermediate circuit 3 rises, but the DC 6 When the voltage is lower than the direct current intermediate voltage command value, a gate pulse is output to the second gate drive circuit 9b so that the second transistor 7b repeats the on / off operation, and a later-described boost chopper operation is performed. It operates so that the DC intermediate voltage becomes the DC intermediate voltage command value. As a result, the power supplied from the AC power supply 1 is limited to a desired input power.

On the other hand, when the AC power supply 1 has a power failure, the power failure detector 11 outputs a signal to the pulse generation circuit 9c, and the pulse generation circuit 9c receives the signal in order to repeat the on / off operation of the second transistor 7b. A gate pulse is output to the two-gate drive circuit 9b to perform a boost chopper operation. As a result, AC power is supplied to the load 6 without a power failure.
Here, when the pulse generation circuit 9c operates the second gate drive circuit 9b and turns on the second transistor 7b by the gate drive signal from the second gate drive circuit 9b, the storage battery 8 is used as a DC power source, and the storage battery 8, current flows through the path of the chopper reactor 7e, the second transistor 7b, and the storage battery 8 while increasing.

  Next, when the second transistor 7b is turned off, a current flows through the path of the chopper reactor 7e, the first free wheel diode 7c, the DC intermediate circuit 3, and the inverter 5, and the second transistor 7b, It operates as a known step-up chopper constituted by the reactor 7e and the first freewheel diode 7c, and supplies DC power to the DC intermediate circuit 3.

  That is, as shown in FIG. 4, the pulse generation circuit 9c performs the PI control process so that the deviation between the storage voltage command value of the storage battery 8 and the actual storage voltage of the storage battery 8 detected by the voltage sensor 13 becomes zero. PI controller 14 and a PI controller that performs PI control processing so that the deviation between the DC intermediate voltage command value of DC intermediate circuit 3 and the actual DC intermediate voltage of DC intermediate circuit 3 detected by voltage sensor 12 becomes zero. 15 and the PI regulator 14 that performs adjustment based on the stored voltage deviation and the adjustment based on the DC intermediate voltage deviation between when the step-up / step-down chopper 7 operates as a step-up chopper and when the step-up / step-down chopper 7 operates as a step-down chopper. The control is performed by switching the PI controller 15 that performs the control.

JP 2001-186689 A (page 3)

  In the conventional uninterruptible power supply, the power failure detector 11 has not detected a power failure, and the DC intermediate voltage of the DC intermediate circuit 3 detected by the voltage sensor 12 is lower than the DC intermediate voltage command value. In the pulse generation circuit 9c, first, the charging of the storage battery 8 is stopped, and when the DC intermediate voltage is still lower than the DC intermediate voltage command value, the step-up / down chopper 7 is operated as a boost chopper, The voltage is restored. That is, a standby time is provided for determining whether or not the DC intermediate voltage has recovered from when the charging of the storage battery 8 is stopped until the storage battery 8 starts discharging.

For this reason, when the direct current intermediate voltage falls below the direct current intermediate voltage command value as a result of a power failure in the alternating current power supply 1, the storage battery 8 is actually used in spite of the fact that the rapid recovery of the direct current intermediate voltage is desired. It takes time until the discharge is started, and the power supply from the storage battery 8 is delayed. As a result, the DC intermediate voltage is further lowered. In order to suppress the decrease in the DC intermediate voltage until the power supply from the storage battery 8 is started, it is necessary to install a DC capacitor having a capacity corresponding to the decrease, and the decrease in the DC intermediate voltage is reduced. The larger the value, the larger the capacity of the DC capacitor, which leads to an increase in cost and an increase in the volume of the entire device.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and even when an event that fluctuates the DC intermediate voltage occurs, such as when an abnormality occurs in the AC power supply, the DC It aims at providing the power converter device which can suppress the fall of an intermediate voltage.

  In order to achieve the above object, a power conversion device according to claim 1 of the present invention includes a rectifier that converts AC power input into DC power, and AC power for load supply by converting the DC power into AC power. An inverter that generates and supplies the AC power for supplying the load to the load, a storage means that stores the DC power, and is connected between the rectifier and the inverter, and is stepped up or stepped down according to an input control signal A step-up / step-down circuit that operates, steps down the DC intermediate voltage between the rectifier and the inverter, charges the power storage means, and boosts the DC intermediate voltage using the stored energy of the power storage means; A DC intermediate voltage detection means for detecting the DC intermediate voltage, a storage voltage detection means for detecting a storage voltage of the storage means, and an index of the DC intermediate voltage. DC intermediate voltage deviation calculating means for calculating a deviation between the value and the actual DC intermediate voltage detected by the DC intermediate voltage detecting means, a target value of the storage voltage of the storage means, and an actual value detected by the storage voltage detection means Storage voltage deviation calculating means for calculating a deviation from the storage voltage, DC intermediate voltage deviation calculated by the DC intermediate voltage deviation calculating means, and storage voltage deviation calculated by the storage voltage deviation calculating means And a step-up / step-down control means for generating the control signal so that the deviation becomes zero.

In the power converter according to claim 2, the step-up / step-down control unit is configured such that the AC power supply input is equal to or higher than a preset threshold value and the actual DC intermediate voltage is smaller than a preset limit start voltage. The first limiting means for limiting the maximum value of the storage voltage deviation calculated by the storage voltage deviation calculation means is provided.
Further, in the power conversion device according to claim 3, the step-up / step-down control means includes an input current detection means for detecting an input current to the rectifier, the AC power supply input is equal to or higher than a preset threshold value, and Second limiting means is provided for limiting the maximum value of the stored voltage deviation calculated by the stored voltage deviation calculating means when the actual input current detected by the input current detecting means is greater than or equal to a preset limit start current. It is characterized by that.

  According to a fourth aspect of the present invention, there is provided the power converter, wherein the inverter generates AC power for supplying the load by using the stored energy of the power storage means when the AC power input is smaller than a preset threshold value. When the AC power supply input is equal to or greater than the threshold value, a preset specified value is subtracted from a DC voltage conversion target value when the rectifier converts the DC power into the DC power. The obtained value is set as the target value of the DC intermediate voltage, and when the AC power supply input is smaller than the threshold value, the DC voltage conversion target value is set as the target value of the DC intermediate voltage.

Further, in the power converter according to claim 5, the step-up / step-down control means performs a proportional-integral control process on a deviation between the DC intermediate voltage deviation and the storage voltage deviation to generate the control signal. It is characterized by.
Furthermore, the power converter according to claim 6 is characterized in that the threshold value of the AC power supply input is set to a value that can be considered that a power failure has occurred in the AC power supply.

  The power conversion device according to the present invention includes a deviation between the target value of the DC intermediate voltage, which is a voltage between the rectifier and the inverter, and the actual DC intermediate voltage, and a deviation between the target value of the storage voltage of the storage means and the actual storage voltage. From these, these deviations are calculated, and a control signal is generated so that these deviations become zero. The step-up / step-down circuit is operated so that the DC intermediate voltage matches the target value or the storage voltage matches the target value in accordance with the control signal. The step-up / step-down circuit can be operated so that the larger of the shortage of each target value among the voltages is matched to the target value, and switching between the control for the storage voltage and the control for the DC intermediate voltage Can be performed accurately.

  Further, according to the power conversion device of the second aspect, when the AC power supply input is equal to or greater than the threshold value and the actual DC intermediate voltage is smaller than the preset limit start voltage, the storage voltage deviation calculating means calculates. Since the maximum value of the stored voltage deviation is limited, for example, as the limit start voltage, the direct current intermediate voltage when the direct current intermediate voltage is smaller than the value that the direct current intermediate voltage can take in a normal state and the alternating current power input falls below the threshold value. By setting the value to a value larger than the value that can be taken, the maximum value of the storage voltage deviation is limited when the DC intermediate voltage falls below the normal value before the AC power input falls below the threshold value. Therefore, at this time, it is easier to control the DC intermediate voltage to match the target value than to control the stored voltage.

  For this reason, if the AC power input falls below the threshold, the DC intermediate voltage may decrease due to the decrease in the AC power input, but the AC power input may fall below the threshold. At a point when it can be assumed that there is an AC power input, the control of the DC intermediate voltage is prioritized over the control of the storage voltage and the control to make the DC intermediate voltage match the target value is started. When the voltage falls below the threshold value, it is possible to suppress a decrease in the DC intermediate voltage caused by the decrease in the AC power supply input.

  According to the power conversion device of claim 3, when the AC power input is equal to or greater than the threshold value and the input current input to the rectifier is equal to or greater than a preset limit start current, the maximum stored voltage deviation Since the value is limited, for example, by setting the value corresponding to the input current that can be considered that the AC input power may be lower than the threshold value as the limit start current, the AC power input is In order to limit the maximum value of the storage voltage deviation at the time when it is predicted that there is a possibility of falling below the threshold before it falls below that threshold, the target DC intermediate voltage is targeted rather than the control of the storage voltage at this point. Control to match the value is facilitated.

  For this reason, if the AC power input falls below the threshold, the DC intermediate voltage may drop due to the AC power input falling, but the AC power input may fall below the threshold. At a point when it can be considered, the control of the DC intermediate voltage is prioritized over the control of the storage voltage, and the control to make the DC intermediate voltage coincide with the target value is started, so the AC power input actually falls below the threshold value. A decrease in the direct current intermediate voltage at the time can be suppressed.

  According to the power conversion device of claim 4, when the AC power input is equal to or greater than the threshold value, a value obtained by subtracting a preset specified value from the DC voltage conversion target value when converting to DC power in the rectifier Is set as the target value of the DC intermediate voltage, for example, by setting a value corresponding to the maximum value of the fluctuation that can be taken by the DC intermediate voltage in the normal state as a specified value, the value becomes a value corresponding to the fluctuation of the DC intermediate voltage that can normally occur. Thus, the DC intermediate voltage is controlled. For this reason, it is possible to operate so as to suppress the fluctuation only when the direct current intermediate voltage fluctuates beyond the fluctuation of the direct current intermediate voltage that can normally be taken.

  Further, when the AC power input is smaller than the threshold value, the DC voltage conversion target value when converting to DC power in the rectifier is set as the DC intermediate voltage target value, so that sufficient power is supplied from the AC power source side. If not, control is performed so that the DC intermediate voltage matches the target value, and the DC intermediate voltage is increased to a value equivalent to the target value of the DC intermediate voltage that is the true target value in advance. When the DC intermediate voltage cannot be sufficiently increased and the DC intermediate voltage decreases, the timing at which the DC intermediate voltage falls below the target value can be delayed, and power supply to the load can be continued accordingly. Can do.

Further, the power conversion device according to claim 5 performs proportional-integral control processing on the deviation between the DC intermediate voltage deviation and the storage voltage deviation to generate the control signal. It is possible to easily generate a control signal capable of achieving both the storage voltage control and the control signal.
In particular, since the power conversion device according to claim 6 sets a value that can be considered that a power failure has occurred in the AC power supply as the threshold value of the AC power input, the AC power input is caused by the occurrence of a power failure in the AC power supply. When the voltage drops, switching between the control for the stored voltage and the control for the DC intermediate voltage can be performed accurately.

It is a block diagram which shows an example of the pulse generation circuit in 1st Embodiment to which this invention is applied. It is a block diagram which shows an example of the pulse generation circuit in 2nd Embodiment to which this invention is applied. It is a block diagram which shows an example of the uninterruptible power supply to which this invention is applied. It is a block diagram which shows an example of the conventional pulse generation circuit.

Embodiments of the present invention will be described below.
First, a first embodiment will be described.
Here, a case where the present invention is applied to an uninterruptible power supply will be described. The basic configuration of the uninterruptible power supply is the same as that of the conventional uninterruptible power supply shown in FIG. 3, and the configuration of the pulse generation circuit 9c is different in the uninterruptible power supply shown in FIG.

FIG. 1 is a block diagram showing a configuration of a pulse generation circuit 9c to which the present invention is applied.
As described with reference to FIG. 3, the pulse generation circuit 9 c includes the detection result of the power failure detector 11 that detects that the AC power source 1 is in a power failure state, the actual DC intermediate of the DC intermediate circuit 3 detected by the voltage sensor 12. The voltage DC and the actual storage voltage BAT of the storage battery 8 detected by the voltage sensor 13 are input.

  In FIG. 1, 21 is a computing unit that calculates the storage voltage deviation ΔBAT, 22 is an upper limiter that limits the maximum value of the storage voltage deviation ΔBAT calculated by the computing unit 21, and 23 is after the limit by the upper limiter 22. The calculator 24 subtracts the DC intermediate voltage deviation ΔDC (described later) or the DC intermediate voltage deviation ΔDC ′ after limitation from the stored voltage deviation ΔBAT ′, and outputs a deviation signal δV. 24 is a deviation signal δV calculated by the calculator 23. PI regulator 25 that performs PI (proportional-integral) control processing and generates a step-up / step-down control signal, and 25 is a PWM signal that generates a PWM control signal by a known procedure based on the step-up / step-down control signal generated by PI regulator 24. The generation unit 26 generates a first gate drive based on the PWM control signal generated by the PWM signal generation unit 25 and the PWM inversion control signal obtained by inverting the PWM control signal by the inversion circuit 27. A dead time generation unit for generating a gate pulse to the circuit 9a and the second gate driving circuit 9b.

Further, 31 is a mode determination unit, 32 is an upper limit value selection unit that selects the upper limit value of the upper limit limiter 22 according to the determination result of the mode determination unit 31, and 33 is the power failure detector 11 and the AC power source 1 is connected. It is a power failure upper limit selection unit that sets the upper limit of the upper limiter 22 to zero when it is detected that a power failure has occurred.
Further, 41 is a DC deviation selection unit that selects a DC deviation according to the detection result of the power failure detector 11, and 42 is an arithmetic unit that calculates a control DC intermediate voltage command value SAdc based on the DC intermediate voltage command value Sdc. 43 is an arithmetic unit for subtracting the actual DC intermediate voltage DC from the control DC intermediate voltage command value SAdc to calculate the DC intermediate voltage deviation ΔDC, and 44 is a DC intermediate voltage according to the detection result of the power failure detector 11. A switching unit 45 that switches the output destination of the deviation ΔDC is a lower limiter that limits the minimum value of the DC intermediate voltage deviation ΔDC.

The computing unit 21 subtracts the actual storage voltage BAT detected by the voltage sensor 13 from the storage voltage command value Sbat preset as the target value of the storage voltage of the storage battery 8, and outputs this as the storage voltage deviation ΔBAT. Since the actual storage voltage BAT takes a value equal to or less than the storage voltage command value Sbat, the storage voltage deviation ΔBAT is a positive value greater than or equal to zero.
The upper limiter 22 sets the maximum value of the storage voltage deviation ΔBAT input from the computing unit 21 as the upper limit value Ha or Hb selected by the upper limit value selection unit 32 or the upper limit set by the upper limit value selection unit 33 during power failure. Limit to zero.

  The mode determination unit 31 includes the actual DC intermediate voltage DC from the voltage sensor 12 and the target value of the DC voltage when the AC power is converted into DC power in the rectifier 2, that is, the target value of the DC intermediate voltage of the DC intermediate circuit 3. The DC intermediate voltage command value Sdc and the control DC intermediate voltage command value SAdc are input. The control DC intermediate voltage command value SAdc is a value obtained by subtracting a DC deviation from the DC intermediate voltage command value Sdc.

  When the actual DC intermediate voltage DC is equal to or greater than the DC intermediate voltage command value Sdc, the mode determination unit 31 outputs a selection signal for selecting the upper limit value Ha in the upper limit value selection unit 32. When the actual direct current intermediate voltage DC is smaller than the control direct current intermediate voltage command value SAdc, the upper limit value selection unit 32 outputs a selection signal for selecting the upper limit value Hb. That is, when the actual direct current intermediate voltage DC is equal to or greater than the control direct current intermediate voltage command value SAdc and smaller than the direct current intermediate voltage command value Sdc, hysteresis is provided by preventing the upper limit value from changing. This prevents the upper limit from changing.

  The upper limit value selection unit 32 selects one of the upper limit values Ha and Hb according to the selection signal from the mode determination unit 31, and sets this as the upper limit value of the upper limit limiter 22. The upper limit value Ha is larger than the upper limit value Hb, and is set to a value that the storage voltage deviation ΔBAT is not limited by the upper limit limiter 22 when the storage battery 8 is charged when the AC power supply 1 is in a non-power failure state. For example, the charging voltage rating value of the storage battery 8 is set. The upper limit value Hb is a value that determines how much control is performed on the storage voltage deviation ΔBAT, and is set to a value equal to or greater than zero. The smaller the value, the smaller the ratio of control to the storage voltage deviation ΔBAT. Become. The upper limit value Hb is set to zero, for example.

When the power failure detector 11 detects that the AC power supply 1 is in a power failure state, the power failure upper limit selection unit 33 selects zero as the upper limit value of the upper limit limiter 22. When it is detected that there is a non-power failure state, the upper limit value Ha or Hb set by the upper limit value selection unit 32 is selected as the upper limit value of the upper limit limiter 22.
The DC deviation selection unit 41 selects zero as the DC deviation when the power failure detector 11 detects that the AC power supply 1 is in a power failure state, and preliminarily stores the DC deviation as a DC deviation when it is detected that the power source is in a non-power failure state. Select the specified value εdc. This prescribed value εdc is a positive fixed value, for example, a direct current intermediate that can be caused by a sudden change in the load amount of the load 6 when the AC power supply 1 is in a non-power failure state and the rectifier 2 is operating normally. It is set to the same level as the maximum value of voltage drop.

The calculator 42 subtracts the DC deviation selected by the DC deviation selector 41 from the DC intermediate voltage command value Sdc and outputs the result to the calculator 42 as a control DC intermediate voltage command value SAdc.
The calculator 43 subtracts the actual DC intermediate voltage DC detected by the voltage sensor 12 from the control DC intermediate voltage command value SAdc calculated by the calculator 42, and outputs the result as a DC intermediate voltage deviation ΔDC to the switching unit 44. To do.

The switching unit 44 operates according to the detection result of the power failure detector 11, and outputs the DC intermediate voltage deviation ΔDC to the lower limiter 45 when the power failure detector 11 detects that the AC power supply 1 is in a non-power failure state. . When the power failure detector 11 detects that the AC power source 1 is in a power failure state, it outputs a DC intermediate voltage deviation ΔDC to the calculator 23.
The lower limiter 45 limits the minimum value of the DC intermediate voltage deviation ΔDC input from the switching unit 44 to zero. The limited DC intermediate voltage deviation ΔDC ′ limited by the lower limiter 45 is subtracted and input to the calculator 23.

The PI controller 24 performs a known PI (proportional-integral) control process on the deviation signal δV input from the computing unit 23 so that the deviation signal δV becomes zero, and the deviation signal δV is a positive value. If there is, a step-up / step-down control signal for charging the storage battery 8 corresponding to δV is generated, and if the deviation signal δV is a negative value, a step-up / step-down control signal for discharging δV from the storage battery 8 is generated. The data is output to the generation unit 25.
The PWM signal generation unit 25 generates a PWM signal by a known procedure based on the step-up / step-down control signal from the PI regulator 24, outputs the PWM signal directly to the dead time generation unit 26, and converts the PWM signal into an inverting circuit. 27.

  The dead time generation unit 26 receives the PWM signal from the PWM signal generation unit 25, the PWM inversion signal from the inversion circuit 27, and the deviation signal δV from the computing unit 23, and the PWM signal is input by the first gate drive circuit 9a. In order to prevent the short circuit between the first transistor 7a and the second transistor 7b by using the PWM signal and PWM inverted signal for the first transistor 7a to be driven as the PWM signal for the second transistor 7b driven by the second gate drive circuit 9b. The first transistor PWM signal and the second transistor PWM signal having a dead time for turning off both the transistors 7a and 7b are generated.

  When the deviation signal δV from the computing unit 23 is a positive value, the first transistor PWM signal is output to the first gate drive circuit 9a, and the step-up / step-down chopper 7 is stepped down. At this time, the second gate drive circuit 9b is not driven. Conversely, when the deviation signal δV is a negative value, the PWM signal for the second transistor is output to the second gate drive circuit 9b, and the step-up / step-down chopper 7 is boosted. At this time, the first gate drive circuit 9a is not driven.

Next, the operation of the first embodiment will be described.
First, the operation at the time of non-power failure will be described.
Usually, the rectifier 2 converts AC power from the AC power source 1 into DC power and outputs the DC power to the DC intermediate circuit 3. The inverter 5 converts the DC power from the DC intermediate circuit 3 into predetermined AC power and supplies the converted AC power to the load 6.
Then, based on the detection result of the voltage sensor 10, the power failure detector 11 determines whether the AC power source 1 is in a power outage state. If the AC power source 1 is not in a power outage state, A specified value εdc, which is a positive fixed value, is selected as the deviation, and a value obtained by subtracting the specified value εdc from the DC intermediate voltage command value Sdc becomes the control DC intermediate voltage command value SAdc.

When the actual direct current intermediate voltage DC detected by the voltage sensor 12 is equal to or greater than the direct current intermediate voltage command value Sdc, the upper limit value selection unit 32 selects the upper limit value Ha based on the determination result in the mode determination unit 31, and Since the AC power supply 1 is in a non-power failure state, the upper limit value selection unit 33 at the time of power failure selects the upper limit value set by the upper limit value selection unit 32, so the upper limit value of the upper limit limiter 22 becomes the upper limit value Ha.
When storage voltage deviation ΔBAT, which is the deviation between actual storage voltage BAT of storage battery 8 and storage voltage command value Sbat, is smaller than upper limit value Ha of upper limiter 22, storage voltage deviation ΔBAT is not limited. For this reason, the storage voltage deviation ΔBAT ′ after the limit is “storage voltage command value Sbat−actual storage voltage BAT”.

On the other hand, when the actual direct current intermediate voltage DC is greater than or equal to the direct current intermediate voltage command value Sdc and greater than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC is a negative value, but the alternating current power supply 1 is not powered. In this state, the DC intermediate voltage deviation ΔDC is supplied to the lower limiter 45 via the switching unit 44 and is limited to zero here. For this reason, the DC intermediate voltage deviation ΔDC ′ after the limit becomes zero.
Therefore, the deviation signal δV calculated by the calculator 23 becomes ΔBAT′−ΔDC ′ = ΔBAT ′, and as a result, “deviation signal δV = storage voltage command value Sbat−actual storage voltage BAT”.

Then, the PI regulator 24 generates a step-up / step-down control signal for controlling the deviation signal δV (= storage voltage command value Sbat−actual storage voltage BAT) to zero, and a PWM signal corresponding thereto is generated by the PWM signal generation unit 25. The dead time generator 26 performs dead time processing based on the generated PWM signal and the PWM inverted signal inverted by the inverter circuit 27.
At this time, since the deviation signal δV (= ΔBAT ′) is a positive value and the step-up / step-down chopper 7 needs to be stepped down, the PWM signal is output to the first gate drive circuit 9a, and the second gate drive circuit 9b Do not drive.
For this reason, only the first transistor 7a is turned on / off, and accordingly, the step-up / step-down chopper 7 performs a step-down operation in the same manner as described above, whereby the storage battery 8 is charged, and the actual storage voltage BAT is stored. Control is performed so as to coincide with the voltage command value Sbat.

  At this time, when the actual storage voltage BAT greatly falls below the storage voltage command value Sbat and the storage voltage deviation ΔBAT exceeds the upper limit value Ha of the upper limit limiter 22, the storage voltage deviation ΔBAT is limited to the upper limit value Ha. For this reason, the storage voltage deviation ΔBAT ′ after the limit becomes the upper limit value Ha, so that the deviation signal δV becomes the “upper limit value Ha”, and the step-down operation is performed so as to perform charging corresponding to the upper limit value Ha. Further, since the upper limit value Ha is set to be equivalent to the rated value of the charging voltage of the storage battery 8, it is possible to avoid charging exceeding the rated value.

  Here, the control DC intermediate voltage command value SAdc is a value obtained by subtracting the specified value εdc from the DC intermediate voltage command value Sdc, and the specified value εdc is a sudden change in the load amount of the load 6 during normal operation in a non-power failure state. Is set to the same level as the maximum value of the DC intermediate voltage drop that can occur. Therefore, the control DC intermediate voltage command value SAdc corresponds to the minimum value that the actual DC intermediate voltage DC can take during normal operation, and the actual DC intermediate voltage DC is equal to or greater than the control DC intermediate voltage command value SAdc (= Adc−εdc). If the actual direct current intermediate voltage DC is less than the control direct current intermediate voltage command value SAdc, the actual direct current intermediate voltage DC can be regarded as being in an allowable range that can be regarded as normal. DC can be considered abnormal.

  Therefore, when the actual direct current intermediate voltage DC is larger than the direct current intermediate voltage command value Sdc and the control direct current intermediate voltage command value SAdc, the actual direct current intermediate voltage DC takes a value within a normal range, and the uninterruptible power supply device Can be determined to be operating normally. Further, since the actual direct current intermediate voltage DC exceeds the direct current intermediate voltage command value Sdc, only the storage voltage control is performed without controlling the direct current intermediate voltage, and the actual storage voltage BAT becomes equal to the storage voltage command value Sbat. The step-up / step-down chopper 7 is stepped down so as to match.

Next, when the actual direct current intermediate voltage DC decreases from the state where the actual direct current intermediate voltage DC is equal to or greater than the direct current intermediate voltage command value Sdc, while the actual direct current intermediate voltage DC is greater than the control direct current intermediate voltage command value SAdc, The upper limit value of the upper limiter 22 is maintained at Ha.
Further, since the actual direct current intermediate voltage DC is larger than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC becomes a negative value and is restricted by the lower limiter 45, and the restricted direct current intermediate voltage deviation ΔDC ′ is zero. It becomes.

  On the other hand, when actual storage voltage BAT is lower than storage voltage command value Sbat and storage voltage deviation ΔBAT is smaller than upper limit value Ha of upper limit limiter 22, storage voltage deviation ΔBAT is not limited. Therefore, deviation signal δV is ΔBAT′−ΔDC ′ = ΔBAT ′ (= storage voltage command value Sbat−actual storage voltage BAT), and the step-down operation is performed so that storage voltage deviation ΔBAT ′ becomes zero. As a result, the storage battery 8 is charged and the storage voltage increases so as to become the storage voltage command value Sbat.

Further, when the storage voltage deviation ΔBAT is larger than the upper limit value Ha of the upper limit limiter 22, the storage voltage deviation ΔBAT is limited to the upper limit value Ha. Therefore, deviation signal δV is ΔBAT′−ΔDC ′ = upper limit value Ha, and the step-down operation is performed so that stored voltage deviation ΔBAT ′ becomes zero.
As described above, when the actual direct current intermediate voltage DC is smaller than the direct current intermediate voltage command value Sdc but larger than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage is in a range that can normally be taken. The intermediate voltage is not controlled, only the storage voltage is controlled, and the step-up / step-down chopper 7 performs only the step-down operation.

When the actual direct current intermediate voltage DC further decreases and falls below the control direct current intermediate voltage command value SAdc, the upper limit value of the upper limit limiter 22 is changed to Hb.
At this time, since the actual direct current intermediate voltage DC is smaller than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC becomes a positive value and larger than the lower limit value zero of the lower limiter 45, and therefore the direct current intermediate voltage deviation ΔDC is limited. The limited DC intermediate voltage deviation ΔDC ′ is “control DC intermediate voltage command value SAdc−actual DC intermediate voltage DC”.

Further, when the storage voltage deviation ΔBAT is larger than the upper limit value Hb (= 0) of the upper limit limiter 22, the storage voltage deviation ΔBAT is limited to the upper limit value Hb (= 0).
Therefore, the deviation signal δV becomes “upper limit value Hb (= 0) − (control direct current intermediate voltage command value SAdc−actual direct current intermediate voltage DC)”, and the step-up / down chopper 7 outputs “control direct current intermediate voltage command value SAdc”. -Boosting is performed so that the actual direct current intermediate voltage DC "becomes zero.

  As described above, when the actual direct current intermediate voltage DC is lower than the control direct current intermediate voltage command value SAdc, the actual direct current intermediate voltage DC is reduced beyond a normal range, and some event occurs that causes the direct current intermediate voltage to fluctuate. Therefore, by limiting the storage voltage deviation ΔBAT to the upper limit value Hb (= 0), the storage battery 8 is not charged, and the control of the DC intermediate voltage is given priority over the control of the storage voltage. To restore the DC intermediate voltage.

Therefore, for example, when the AC power supply 1 is in a non-power failure state and operates normally and the actual DC intermediate voltage DC is equal to or greater than the DC intermediate voltage command value Sdc, it is not necessary to control the DC intermediate voltage. The step-up / step-down chopper 7 performs a step-down operation so that the stored voltage matches the stored voltage command value Sbat.
From this state, when the AC power supply input decreases due to an abnormality on the AC power supply 1 side, the actual direct current intermediate voltage DC decreases with this decrease, and the actual direct current intermediate voltage DC is larger than the control direct current intermediate voltage command value SAdc. Since the DC intermediate voltage is within the normal range, the control of the stored voltage is performed with priority.

  When the actual direct current intermediate voltage DC further decreases and falls below the control direct current intermediate voltage command value SAdc, the storage voltage deviation ΔBAT is limited to the upper limit value Hb (= 0) or less, giving priority to the control of the direct current intermediate voltage. Then, the step-up / step-down chopper 7 is boosted. That is, when the actual DC intermediate voltage DC falls below the range of DC intermediate voltages that can normally be taken, the boosting operation is started and the DC intermediate voltage is recovered.

  For this reason, for example, when a power failure occurs in the AC power source 1, the DC intermediate voltage is recovered at an early stage when the AC power source voltage starts to decrease before the AC power source 1 actually reaches the power failure state. As described above, the boosting operation can be started. For this reason, when AC power supply 1 will be in a power failure state, it can suppress that a direct current intermediate voltage falls in connection with this, ie, the amount of fall of direct current intermediate voltage can be made small.

  Further, for example, when the direct current intermediate voltage decreases due to a temporary change in the load amount of the load 6 from the state where the alternating current power supply 1 is operating normally, the actual direct current intermediate voltage DC is lower than the direct current intermediate voltage command value Sdc. However, when the reduction amount is a reduction amount that can normally occur, the actual direct current intermediate voltage DC takes a value larger than the control direct current intermediate voltage command value SAdc. For this reason, the DC intermediate voltage deviation ΔDC is limited to zero by the lower limiter 45, and the control of the storage voltage is performed with priority. When the load amount returns to the normal load amount and the DC intermediate voltage increases accordingly, the actual DC intermediate voltage DC continues to exceed the control DC intermediate voltage command value SAdc, and the DC intermediate voltage deviation ΔDC is reduced by the lower limiter 45. Since it is limited to zero, the control of the storage voltage is continued with priority. Accordingly, even when the actual direct current intermediate voltage DC varies with the fluctuation of the load amount of the load 6 within a temporary allowable range, the control switches from the stored voltage control to the direct current intermediate voltage control. That is, it can be avoided that the control is switched from the power storage to the storage battery 8 to the discharge from the storage battery 8.

Next, the operation when the AC power supply 1 is in a power failure state will be described.
When a power failure is detected by the power failure detector 11, zero is selected as the DC deviation in the DC deviation selection unit 41, so that the control DC intermediate voltage command value SAdc becomes the DC intermediate voltage command value Sdc. Moreover, since it is a power failure state, the switching unit 44 directly inputs the DC intermediate voltage deviation ΔDC calculated by the calculator 43 to the calculator 23, and the DC intermediate voltage deviation ΔDC is not limited. Moreover, since it is a power failure state, the upper limit value selector 33 at the time of power failure sets the upper limit value of the upper limiter 22 to zero.
For this reason, the direct current intermediate voltage deviation ΔDC becomes “direct current intermediate voltage command value Sdc−actual direct current intermediate voltage DC” and the deviation signal δV = ΔBAT′−ΔDC = −ΔDC. The direct current intermediate voltage is controlled so as to coincide with the command value Sdc.

  Therefore, when the actual direct current intermediate voltage DC is smaller than the direct current intermediate voltage command value Sdc, the step-up / step-down chopper 7 performs a boosting operation using the storage battery 8 as an energy source, and boosts the direct current intermediate voltage to obtain the direct current intermediate voltage. The DC intermediate voltage command value Sdc is maintained and power supply to the load 6 is continued. Conversely, when the actual DC intermediate voltage DC is greater than the DC intermediate voltage command value Sdc, the step-up / step-down chopper 7 performs a step-down operation to charge the storage battery 8 to reduce the DC intermediate voltage. As a result, the DC intermediate voltage is maintained at the DC intermediate voltage command value Sdc, and the power supply to the load 6 is continued although the AC power supply 1 is in a power failure state.

Thus, when the AC power supply 1 is in a power failure state, the storage voltage deviation ΔBAT is limited to zero, the storage voltage is not controlled, and the control of the DC intermediate voltage is given priority. The DC intermediate voltage command value Sdc can be surely matched.
In the non-power failure state, the control is performed so that the direct current intermediate voltage command value Sdc and the actual direct current intermediate voltage DC do not coincide with the control direct current intermediate voltage command value SAdc. The DC intermediate voltage can be maintained at the DC intermediate voltage command value Sdc even when the DC intermediate voltage is not controlled by the rectifier 2 due to the power failure state.

  As described above, when the AC power supply 1 is in a non-power failure state or not in a power failure state, it is possible to suppress a decrease in the actual DC intermediate voltage DC from the DC intermediate voltage command value Sdc, Since the reduction amount can be reduced, the capacity of the DC capacitor 4 for maintaining the DC intermediate voltage at the DC intermediate voltage command value Sdc can be reduced. Therefore, the apparatus can be reduced in size accordingly.

Next, a second embodiment of the present invention will be described.
FIG. 2 is a block diagram showing the configuration of the pulse generation circuit 9c of the uninterruptible power supply according to the second embodiment.
The basic configuration of the uninterruptible power supply in the second embodiment is the same as that of the conventional uninterruptible power supply shown in FIG. 3, and in the uninterruptible power supply shown in FIG. The configuration is different. The same parts as those of the pulse generation circuit 9c in FIG. 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The pulse generation circuit 9c according to the second embodiment is different from the pulse generation circuit 9c according to the first embodiment shown in FIG. 1 in that it replaces the mode determination unit 31 with a current sensor 51, an amplitude calculation unit 52, and a rectifier state determination. The upper limit value selection unit 32 selects the upper limit value Ha or Hb based on the determination result of the rectifier state determination unit 53 instead of the mode determination unit 31.
Current sensor 51 is provided between AC power supply 1 and rectifier 2 and detects an input current from AC power supply 1 to the uninterruptible power supply.
The amplitude calculator 52 calculates the amplitude based on the detection signal from the current sensor 51, and outputs this as the input current amplitude Wi.

  The rectifier state determination unit 53 inputs the input current amplitude Wi calculated by the amplitude calculation unit 52 and the preset amplitude command value SWi, and when the input current amplitude Wi is smaller than the amplitude command value SWi, the charge rated voltage value A signal for selecting a corresponding upper limit value Ha is output to the upper limit value selection unit 32. When the input current amplitude Wi is equal to or larger than the amplitude command value SWi, an upper limit for determining how much control is performed on the storage voltage deviation ΔBAT. A signal for selecting the value Hb (for example, zero) is output to the upper limit selection unit 32. The amplitude command value SWi is set to a value that can be normally taken by the amplitude of the input current in a state in which normal operation is performed in a non-power failure state. That is, it is set to a value that can determine from the amplitude of the input current whether it is in a state that causes a drop in the DC intermediate voltage.

Next, the operation of the second embodiment will be described.
First, the operation when the AC power supply 1 is in a non-power failure state will be described.
Usually, the rectifier 2 converts AC power from the AC power source 1 into DC power and outputs the DC power to the DC intermediate circuit 3. The inverter 5 converts the DC power from the DC intermediate circuit 3 into predetermined AC power and supplies the converted AC power to the load 6.
When the power failure detector 11 determines that the AC power supply 1 is in a non-power failure state, the DC deviation selection unit 41 selects a specified value εdc that is a positive fixed value as the DC deviation, and this specified value εdc. Is subtracted from the DC intermediate voltage command value Sdc to become the control DC intermediate voltage command value SAdc. Further, since it is a non-power failure state, the switching unit 44 outputs the DC intermediate voltage deviation ΔDC calculated by the calculator 43 to the lower limiter 45. For this reason, the lower limit value of the DC intermediate voltage deviation ΔDC is limited to zero. Further, the upper limit value selector 33 at the time of power failure selects the upper limit value Ha or Hb selected by the upper limit value selector 32 as the upper limit value of the upper limiter 22.

When the actual direct current intermediate voltage DC is greater than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC becomes a negative value, but is limited to zero by the lower limiter 45 and the restricted direct current intermediate voltage deviation ΔDC. ′ Becomes zero.
At this time, when it is determined that the input current amplitude Wi calculated by the amplitude calculator 52 is smaller than the amplitude command value SWi and the load 6 is stably consuming power, the storage battery is used as the upper limit value of the upper limiter 22. An upper limit value Ha corresponding to the rated charging voltage value of 8 is set. Further, when the storage voltage deviation ΔBAT is smaller than the upper limit value Ha, the storage voltage deviation ΔBAT is not limited by the upper limit limiter 22. For this reason, the storage voltage deviation ΔBAT ′ after the limit is “storage voltage command value Sbat−actual storage voltage BAT”.

Therefore, deviation signal δV calculated by calculator 23 is ΔBAT′−ΔDC ′ = (storage voltage command value Sbat−actual storage voltage BAT).
For this reason, the PI regulator 24 generates a step-up / step-down control signal for controlling the deviation signal δV (= storage voltage command value Sbat−actual storage voltage BAT) to zero, and a PWM signal corresponding thereto is generated as a PWM signal generation unit 25. The dead time generation unit 26 performs dead time processing based on the generated PWM signal and the PWM inverted signal inverted by the inverting circuit 27. Since the deviation signal δV is a positive value, the PWM signal is output to the first gate drive circuit 9a to perform the step-down operation, and the second gate drive circuit 9b is not driven.

For this reason, only the first transistor 7a is turned on / off, whereby the same step-down operation as described above is performed, the storage battery 8 is charged, and the actual storage voltage BAT matches the storage voltage command value Sbat. Will be controlled.
At this time, when the actual storage voltage BAT greatly falls below the storage voltage command value Sbat and the storage voltage deviation ΔBAT exceeds the upper limit value Ha of the upper limit limiter 22, the storage voltage deviation ΔBAT is limited to the upper limit value Ha. Therefore, storage voltage deviation ΔBAT ′ after the limit becomes “upper limit value Ha”, so that deviation signal δV becomes upper limit value Ha, and the step-down operation is performed so as to perform charging corresponding to upper limit value Ha. Here, since the upper limit value Ha is set to be equivalent to the rated value of the charging voltage of the storage battery 8, it is possible to avoid charging exceeding the rated value.

  As described above, when the actual direct current intermediate voltage DC is larger than the control direct current intermediate voltage command value SAdc and the input current amplitude Wi is smaller than the amplitude command value SWi, the actual direct current intermediate voltage DC is within a normal range. In addition, since the direct current intermediate voltage does not tend to decrease, the direct current intermediate voltage is not controlled, only the stored voltage is controlled, and the step-up / step-down chopper 7 is stepped down to charge the storage battery 8.

On the other hand, when the input current amplitude Wi calculated by the amplitude calculation unit 52 is greater than or equal to the amplitude command value SWi and the DC intermediate voltage is predicted to be lower than the value that the supply current to the load 6 can normally take, the upper limit An upper limit value Hb (= 0) is set as the upper limit value of the limiter 22. For this reason, the storage voltage deviation ΔBAT is limited to the upper limit value Hb (= 0).
When the actual direct current intermediate voltage DC is larger than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC is a negative value, so that the direct current intermediate voltage deviation ΔDC is limited to zero by the lower limiter 45 and is limited. ′ Becomes zero.
Therefore, the deviation signal δV calculated by the calculator 23 becomes ΔBAT′−ΔDC ′ = upper limit value Hb (= 0) −0 = 0, and the step-up / down chopper 7 is not driven.

  Thus, although the actual direct current intermediate voltage DC is greater than the control direct current intermediate voltage command value SAdc, the input current amplitude Wi is greater than or equal to the amplitude command value SWi, and the actual direct current intermediate voltage DC is within the allowable range. However, when the input current amplitude Wi is relatively large and the DC intermediate voltage is predicted to decrease, the storage voltage deviation ΔBAT is limited to the upper limit value Hb (0) and the step-down operation is not performed. As a result, the step-down / step-up chopper 7 can be stepped down in a state where the direct current intermediate voltage is predicted to be reduced, and further reduction of the direct current intermediate voltage can be avoided.

On the other hand, when the actual direct current intermediate voltage DC is smaller than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC is a positive value, and is not limited by the lower limiter 45. The deviation ΔDC ′ is “control direct current intermediate voltage command value SAdc−actual direct current intermediate voltage DC”.
At this time, when the input current amplitude Wi calculated by the amplitude calculator 52 is smaller than the amplitude command value SWi, the upper limit value Ha corresponding to the rated charging voltage value for the storage battery 8 is set as the upper limit value of the upper limiter 22. The For this reason, when the storage voltage deviation ΔBAT is smaller than the upper limit value Ha, the upper limit limiter 22 is not limited, and the storage voltage deviation ΔBAT ′ after the limit is “storage voltage command value Sbat−actual storage voltage BAT”.

  Therefore, deviation signal δV is ΔBAT′−ΔDC ′ = (storage voltage command value Sbat−actual storage voltage BAT) − (control direct current intermediate voltage command value SAdc−actual direct current intermediate voltage DC), and deviation signal δV is zero. Control is performed so that For this reason, when the storage voltage deviation ΔBAT ′ is larger than the DC intermediate voltage deviation ΔDC ′, the step-up / step-down chopper 7 performs a step-down operation so as to perform charging corresponding to these differences, and when the DC intermediate voltage deviation ΔDC ′ is larger. The step-up / step-down chopper 7 performs a boosting operation so as to perform a discharge corresponding to the difference. As a result, the actual storage voltage BAT is controlled to match the storage voltage command value Sbat, and the actual DC intermediate voltage DC is controlled to match the control DC intermediate voltage command value SAdc.

When the storage voltage deviation ΔBAT becomes larger than the upper limit value Ha from this state, the storage voltage deviation ΔBAT is limited by the upper limit limiter 22, and the storage voltage deviation ΔBAT ′ after the limit becomes the upper limit value Ha.
Therefore, the deviation signal δV becomes “upper limit value Ha− (control direct current intermediate voltage command value SAdc−actual direct current intermediate voltage DC)”, and when the upper limit value Ha is larger than the direct current intermediate voltage deviation ΔDC ′, the deviation signal The step-up / step-down chopper 7 performs a step-down operation so as to perform charging corresponding to δV, and when the DC intermediate voltage deviation ΔDC ′ is larger, the step-up / step-down chopper 7 performs step-up operation so as to perform step-up corresponding to the deviation signal δV. Boost DC intermediate voltage.

  Thus, when the actual direct current intermediate voltage DC falls below the control direct current intermediate voltage command value SAdc, the actual direct current intermediate voltage DC has dropped beyond the normal range, so that the boost operation is performed to Although recovery is attempted, when it is predicted that the input current amplitude Wi is smaller than the amplitude command value SWi and the DC intermediate voltage is not further reduced, the storage battery 8 is also charged, while the DC intermediate voltage is boosted. Charge to 8.

On the other hand, when the input current amplitude Wi calculated by the amplitude calculation unit 52 is equal to or larger than the amplitude command value SWi and the supply current to the load 6 is predicted to be larger than usual and the DC intermediate voltage tends to decrease, The upper limit value Hb (= 0) is set as the upper limit value of the upper limiter 22.
For this reason, the storage voltage deviation ΔBAT is limited by the upper limiter 22, and the storage voltage deviation ΔBAT ′ after the limit becomes the “upper limit value Hb”.

When the actual direct current intermediate voltage DC is smaller than the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC is a positive value. Therefore, the direct current intermediate voltage deviation ΔDC is not limited by the lower limiter 45 and is limited. 'Becomes "control direct current intermediate voltage command value SAdc-actual direct current intermediate voltage DC".
Therefore, the deviation signal δV becomes ΔBAT′−ΔDC ′ = upper limit value Hb (= 0) − (control direct current intermediate voltage command value SAdc−actual direct current intermediate voltage DC), and therefore the direct current intermediate voltage deviation ΔDC becomes zero. Thus, the step-up / step-down chopper 7 performs a boosting operation.

  Thus, the actual direct current intermediate voltage DC is smaller than the control direct current intermediate voltage command value SAdc, the input current amplitude Wi is greater than or equal to the amplitude command value SWi, the actual direct current intermediate voltage DC is below the allowable range, and the input current When the amplitude Wi is relatively large and the DC intermediate voltage is predicted to further decrease, the storage voltage deviation ΔBAT is limited to the upper limit value Hb (= 0), the storage voltage is not controlled, and the control of the DC intermediate voltage is given priority. To restore the DC intermediate voltage.

Therefore, for example, in a state where the AC power supply 1 is operating normally and the actual DC intermediate voltage DC is operating in a state exceeding the control DC intermediate voltage command value SAdc, the input current amplitude Wi is smaller than the amplitude command value SWi. In some cases, the actual direct current intermediate voltage DC is within the normal range and the direct current intermediate voltage does not tend to decrease. Therefore, only the storage voltage is controlled to charge the storage battery 8.
From this state, for example, when the power consumption of the load 6 increases or the power supplied from the AC power source 1 is limited, the input current from the AC power source 1 increases, and the amplitude calculation unit 52 calculates the current. When the input current amplitude Wi is equal to or greater than the amplitude command value SWi, the upper limit value of the upper limit limiter 22 is changed to Hb (= 0).

  As a result, the stored voltage deviation ΔBAT is limited to the upper limit value Hb (= 0), the step-down operation of the step-up / step-down chopper 7 is stopped, and neither the step-down operation nor the step-up operation is performed. Therefore, although the actual direct current intermediate voltage DC exceeds the control direct current intermediate voltage command value SAdc, when the direct current intermediate voltage is predicted to decrease thereafter, the charging of the storage battery 8 is stopped. It is avoided that the decrease in the DC intermediate voltage that is expected to occur later and the decrease in the DC intermediate voltage caused by charging the storage battery 8 work together.

  From this state, when the actual direct current intermediate voltage DC further decreases and falls below the control direct current intermediate voltage command value SAdc, the direct current intermediate voltage deviation ΔDC becomes a positive value. At this time, the input current amplitude Wi is equal to or greater than the amplitude command value SWi. Since storage voltage deviation ΔBAT is limited to upper limit value Hb (= 0), control of storage voltage is not performed, control of DC intermediate voltage is performed with priority, and recovery of actual DC intermediate voltage DC is achieved. become.

  Therefore, when it is predicted that the DC intermediate voltage will decrease based on the input current amplitude Wi, by stopping charging the storage battery 8 before the actual DC intermediate voltage DC falls below the control DC intermediate voltage command value SAdc, When the direct current intermediate voltage DC falls below the control direct current intermediate voltage command value SAdc, priority is given to the control of the direct current intermediate voltage, and the step-up / step-down chopper 7 is boosted so that the direct current intermediate voltage DC is reduced. Since boosting of the intermediate voltage is intended, suppression of fluctuations in the DC intermediate voltage can be started from an earlier stage, and as a result, the amount of decrease in the DC intermediate voltage can be reduced.

  If the DC intermediate voltage is not expected to decrease based on the input current amplitude Wi, when the actual DC intermediate voltage DC exceeds the control DC intermediate voltage command value SAdc, the storage battery 8 is charged with priority given to the control of the storage voltage. As shown, when the actual direct current intermediate voltage DC is lower than the control direct current intermediate voltage command value SAdc, the storage voltage and direct current intermediate voltage are controlled. Charging can be performed.

  Also in the second embodiment, the step-up / step-down chopper 7 is boosted when the actual direct current intermediate voltage DC falls below the control direct current intermediate voltage command value SAdc. When a power failure occurs, the boosting operation may be started so as to recover the DC intermediate voltage at an early stage when the AC power supply voltage starts to decrease before the AC power source 1 actually reaches the power failure state. it can. Accordingly, when the AC power source 1 is determined to be in a power outage state by the power outage detector 11, the boosting operation has already been performed, so that the DC intermediate voltage decreases when the AC power source 1 enters the power outage state. This can be suppressed, that is, the amount of decrease in the DC intermediate voltage can be reduced.

Next, the operation when the AC power supply 1 is in a power failure state will be described.
When the power failure detector 11 detects that the AC power source 1 is in a power failure state, the DC deviation selection unit 41 selects zero as the DC deviation, so that the control DC intermediate voltage command value SAdc is the DC intermediate voltage command. It becomes the value Sdc. The DC intermediate voltage deviation ΔDC is directly input to the calculator 23 by the switching unit 44 and is not limited by the lower limiter 45. In addition, since the power failure state occurs, zero is selected as the upper limit value by the power failure upper limit value selection unit 33. Therefore, the upper limit value of the upper limit limiter 22 is zero, and the storage voltage deviation ΔBAT is limited to zero.
Therefore, the deviation signal δV is ΔBAT′−ΔDC ′ = − ΔDC ′ = (DC intermediate voltage command value Sdc−actual DC intermediate voltage DC).

  Therefore, when the actual direct current intermediate voltage DC is smaller than the direct current intermediate voltage command value Sdc, the step-up / step-down chopper 7 performs a boosting operation using the storage battery 8 as an energy source, and boosts the direct current intermediate voltage to obtain the direct current intermediate voltage. The DC intermediate voltage command value Sdc is maintained and power supply to the load 6 is continued. Conversely, when the actual DC intermediate voltage DC is greater than the DC intermediate voltage command value Sdc, the step-up / step-down chopper 7 performs a step-down operation to charge the storage battery 8 to reduce the DC intermediate voltage. As a result, the DC intermediate voltage is maintained at the DC intermediate voltage command value Sdc, and the power supply to the load 6 is continued although the AC power supply 1 is in a power failure state.

Thus, when AC power supply 1 is in a power failure state, storage voltage deviation ΔBAT is limited to zero, and control for making the actual storage voltage coincide with storage voltage command value Sbat is not performed. Since only the control for matching the voltage command value Sdc is performed, the DC intermediate voltage can be more reliably matched with the DC intermediate voltage command value Sdc.
In the non-power failure state, the control is performed so that the direct current intermediate voltage command value Sdc and the actual direct current intermediate voltage DC do not coincide with the control direct current intermediate voltage command value SAdc. The DC intermediate voltage can be maintained at the DC intermediate voltage command value Sdc even when the DC intermediate voltage is not controlled by the rectifier 2 due to the power failure state.

  As described above, not only when the AC power source 1 is in a non-power-out state or in a power-out state, it is possible to suppress a decrease in the actual DC intermediate voltage DC from the DC intermediate voltage command value Sdc. In this case as well, the capacity of the DC capacitor 4 for maintaining the DC intermediate voltage at the DC intermediate voltage command value Sdc can be reduced as in the first embodiment. . Therefore, the apparatus can be reduced in size accordingly.

  In the second embodiment, the case where the amplitude of the input current is calculated based on the detection signal of the current sensor 51 and the DC intermediate voltage is predicted to be reduced based on this is described. It may be possible to predict whether or not the DC intermediate voltage is reduced by calculating an average value of the current and determining whether or not the average value exceeds a normal average value.

  In each of the above embodiments, the case where the present invention is applied to an uninterruptible power supply has been described. However, the present invention is not limited to this, and after converting input AC power to DC power, convert it to AC power again. Any power conversion device having a mode for supplying power to the load 6 and a mode for supplying power to the load 6 using the stored energy of the storage battery 8 without using the input AC power can be applied. .

Further, the case where the PI control process is performed on the deviation between the storage voltage deviation ΔBAT and the direct current intermediate voltage deviation ΔDC has been described, but the present invention is not limited to this. For example, the actual detection signal matches the target value, such as PID control. Even a control method for making it apply can be applied.
Further, the case where the step-up / step-down chopper 7 shown in FIG. 3 is applied as the step-up / step-down circuit has been described. However, the present invention is not limited to this, and the step-up / step-down operation is switched according to the step-up / step-down control signal. Any buck-boost circuit can be applied.

  In the above embodiment, the storage battery 8 corresponds to the storage means, the step-up / step-down chopper 7 corresponds to the step-up / step-down circuit, the arithmetic unit 23, the PI regulator 24, the PWM signal generation unit 25, the dead time generation unit 26, The first gate drive circuit 9a and the second gate drive circuit 9b correspond to the step-up / step-down control means, the voltage sensor 12 corresponds to the DC intermediate voltage detection means, the voltage sensor 13 corresponds to the stored voltage detection means, and the arithmetic unit 43 Corresponds to the DC intermediate voltage deviation calculation means, and the calculator 21 corresponds to the storage voltage deviation calculation means.

In the first embodiment, when the mode determination unit 31 detects that the actual DC intermediate voltage DC is lower than the control DC intermediate voltage command value SAdc (limit start voltage), the upper limit value selection unit 32 sets the upper limit value. The process of selecting Hb and limiting the storage voltage deviation ΔBAT to the upper limit value Hb by the upper limiter 22 in response to this selection corresponds to the first limiting means.
In the second embodiment, the current sensor 51 corresponds to the input current detection means, and the input current amplitude Wi calculated by the amplitude calculation unit 52 based on the detection signal of the current sensor 51 is the amplitude command value SWi (limit start current). ) When the upper limit value selection unit 32 selects the upper limit value Hb and the upper limit limiter 22 limits the storage voltage deviation ΔBAT to the upper limit value Hb in response to this, the second limit means corresponds to the above. .

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier 3 DC intermediate circuit 4 DC capacitor 5 Inverter 6 Load 7 Buck-boost chopper 7a 1st transistor 7b 2nd transistor 8 Storage battery 9 Chopper control circuit 9a 1st gate drive circuit 9b 2nd gate drive circuit 10 Voltage sensor 11 Power failure detector 12, 13 Voltage sensor 22 Upper limit limiter 31 Mode determination unit 32 Upper limit value selection unit 51 Current sensor 52 Amplitude calculation unit 53 Rectifier state determination unit

Claims (6)

A rectifier that converts AC power input to DC power;
An inverter for converting the DC power into AC power to generate AC power for load supply and supplying the AC power for load supply to the load;
Power storage means for storing the DC power;
Connected between the rectifier and the inverter, performs a step-up or step-down operation according to an input control signal, steps down a DC intermediate voltage between the rectifier and the inverter, and charges the power storage means. A step-up / step-down circuit that boosts the DC intermediate voltage using the stored energy of the power storage means,
DC intermediate voltage detecting means for detecting the DC intermediate voltage;
Storage voltage detection means for detecting the storage voltage of the storage means;
DC intermediate voltage deviation calculating means for calculating a deviation between the target value of the DC intermediate voltage and the actual DC intermediate voltage detected by the DC intermediate voltage detecting means;
Storage voltage deviation calculation means for calculating a deviation between a target value of the storage voltage of the storage means and the actual storage voltage detected by the storage voltage detection means;
These deviations are calculated from the DC intermediate voltage deviation calculated by the DC intermediate voltage deviation calculating means and the storage voltage deviation calculated by the storage voltage deviation calculating means, and the control signal is set so that this deviation becomes zero. And a step-up / step-down control means for generating the power conversion device.   The step-up / step-down control means stores the power stored in the power storage voltage deviation calculating means when the AC power supply input is equal to or higher than a preset threshold value and the actual DC intermediate voltage is lower than a preset limit start voltage. The power conversion device according to claim 1, further comprising first limiting means for limiting a maximum value of the voltage deviation. The step-up / step-down control means includes
An input current detecting means for detecting an input current to the rectifier;
When the AC power supply input is greater than or equal to a preset threshold and the actual input current detected by the input current detection means is greater than or equal to a preset limit start current, the storage voltage deviation calculation means is calculated. The power converter according to claim 1, further comprising a second limiting unit that limits a maximum value of the stored voltage deviation. The inverter is a power conversion device configured to generate AC power for supplying the load by using stored energy of the power storage means when the AC power supply input is smaller than a preset threshold value,
When the AC power supply input is greater than or equal to the threshold value, a value obtained by subtracting a preset specified value from a DC voltage conversion target value when the rectifier converts the DC power into the DC power is set as the target value of the DC intermediate voltage. ,
The DC voltage conversion target value is set as a target value of the DC intermediate voltage when the AC power supply input is smaller than the threshold value. Power conversion device.   5. The step-up / step-down control means generates a control signal by performing a proportional-integral control process on a deviation between the DC intermediate voltage deviation and the storage voltage deviation. The power converter of any one of Claims.   The power conversion according to any one of claims 1 to 5, wherein the threshold value of the AC power supply input is set to a value that can be considered that a power failure has occurred in the AC power supply. apparatus.

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