JP2023012259A - Uninterruptible power supply system - Google Patents

Abstract

To provide an uninterruptible power supply system capable of suppressing an increase in size and cost of an uninterruptible power supply device while preventing a cross current from flowing between different uninterruptible power supply devices.SOLUTION: An uninterruptible power supply system 100 includes a plurality of uninterruptible power supply devices 10 connected to each other in parallel and for supplying power to a load 103. Each of the plurality of uninterruptible power supply devices includes a converter 1 for converting AC power supplied from an AC power source 101 to DC power, an inverter 3 for converting DC power supplied from the converter or a power storage unit 102 that stores DC power to AC power, and a control unit 6 for generating a PWM carrier signal that serves as a reference for a PWM signal that controls the converter and inverter.SELECTED DRAWING: Figure 1

Description

The present invention relates to an uninterruptible power supply system, and more particularly to an uninterruptible power supply system comprising a plurality of uninterruptible power supplies connected in parallel.

Conventionally, an uninterruptible power supply system including a plurality of uninterruptible power supplies connected in parallel has been disclosed (see, for example, Patent Document 1).

The aforementioned Patent Literature 1 discloses an uninterruptible power supply system including a plurality of uninterruptible power supplies connected in parallel. Power is supplied to the UPS load from each of the plurality of uninterruptible power supplies. Each of the plurality of uninterruptible power supplies includes a converter that converts AC power input into DC power, and an inverter that converts DC power from the converter or storage battery into AC power. Also, each of the plurality of uninterruptible power supplies includes a selective contactor that switches whether to transmit power from the inverter to the load, and a reactor that is provided downstream of the selective contactor. Since the impedance of the reactor is relatively large, the impedance between the different uninterruptible power supply systems becomes relatively large, and cross currents are suppressed from flowing between the different uninterruptible power supply systems.

JP 2007-215344 A

However, in the uninterruptible power supply system described in Patent Literature 1, the reactor included in each of the plurality of uninterruptible power supplies suppresses cross currents from flowing between different uninterruptible power supplies. Therefore, there is a problem that the cost of the uninterruptible power supply increases due to the reactor and the size of the reactor increases.

The present invention has been made to solve the problems described above, and one object of the present invention is to reduce the cost of the uninterruptible power supply while suppressing cross currents between different uninterruptible power supplies. To provide an uninterruptible power supply system capable of suppressing an increase in size and increase in size, and in particular, connecting uninterruptible power supplies with short wiring in order to reduce the installation space of the uninterruptible power supply system. To provide an uninterruptible power supply system capable of suppressing an increase in cost and an increase in size of an uninterruptible power supply while suppressing a cross current flowing between different uninterruptible power supplies.

To achieve the above object, an uninterruptible power supply system according to one aspect of the present invention includes a plurality of uninterruptible power supply units connected in parallel to each other and supplying power to a load. Each of the devices includes a converter that converts AC power supplied from an AC power supply into DC power, an inverter that converts DC power supplied from the converter or a power storage unit that stores DC power into AC power, and a converter and inverter. a control unit that generates a PWM carrier signal that serves as a reference for the PWM signal to be controlled, and the control unit of each of the plurality of uninterruptible power supply units synchronizes the PWM carrier signals between different uninterruptible power supply units. By generating a PWM carrier synchronization signal and correcting the frequency of the PWM carrier signal based on the PWM carrier synchronization signal, the PWM carrier signal of the uninterruptible power supply provided by itself and the other uninterruptible power supply It is configured to perform control to reduce the phase difference between PWM carriers, which is the phase difference with the PWM carrier signal.

In the uninterruptible power supply system according to one aspect of the present invention, as described above, the control unit of each of the plurality of uninterruptible power supplies corrects the frequency of the PWM carrier signal based on the PWM carrier synchronization signal, whereby the PWM carrier and a control unit that performs control to reduce the interphase difference. As a result, even if an element such as a reactor is provided in the uninterruptible power supply and the impedance between the uninterruptible power supplies is not increased, the control unit reduces the phase difference between the PWM carriers to operate a plurality of uninterruptible power supplies. By synchronizing the respective inverter output voltages, it is possible to suppress cross currents (high frequency cross currents) from flowing between the uninterruptible power supplies. As a result, the cross current (high frequency cross current) is suppressed by the control unit provided in advance, so unlike the case where an element such as a reactor is provided in the uninterruptible power supply, the cross current flows between different uninterruptible power supplies. It is possible to suppress the increase in the size and cost of the uninterruptible power supply while suppressing the In addition, even if the impedance between the uninterruptible power supply units is small by connecting the uninterruptible power supply units with short wiring without using a reactor or the like, it is possible to prevent cross currents (high-frequency cross current) from flowing between different uninterruptible power supply units. can be suppressed.

In the uninterruptible power supply system according to the above aspect, preferably, the control unit of each of the plurality of uninterruptible power supplies includes a PWM carrier synchronization signal for the uninterruptible power supply in which it is provided and a PWM carrier synchronization signal for the other uninterruptible power supply. By correcting the frequency of the PWM carrier signal so as to reduce the phase difference with the carrier synchronization signal, control is performed to reduce the phase difference between PWM carriers. According to this configuration, the phase difference between PWM carriers can be easily reduced by performing control to reduce the phase difference between the PWM carrier synchronization signals of different uninterruptible power supplies.

In this case, preferably, the control unit of each of the plurality of uninterruptible power supplies is based on the PWM carrier synchronization signal of its own uninterruptible power supply and the PWM carrier synchronization signals of the other uninterruptible power supplies. By generating a reference synchronization signal and performing control to reduce the synchronization signal phase difference, which is the phase difference between the reference synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply in which the self is provided, It is configured to perform control to reduce the phase difference between the PWM carrier synchronization signal of the uninterruptible power supply and the PWM carrier synchronization signal of another uninterruptible power supply. With this configuration, each of the plurality of uninterruptible power supplies is the phase difference between the reference synchronization signal that serves as the reference for the PWM carrier synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply provided therein. By reducing the synchronization signal phase difference, the PWM carrier synchronization signals of each of the plurality of uninterruptible power supplies can be synchronized based on the reference synchronization signal. As a result, it is possible to easily reduce the phase difference between the PWM carrier synchronization signals of different uninterruptible power supplies.

In the uninterruptible power supply system in which the control unit generates the reference synchronization signal, preferably, the control unit of each of the plurality of uninterruptible power supply units is configured so that the PWM carrier synchronization signal of the uninterruptible power supply unit provided therein has a predetermined value and a second period during which the PWM carrier synchronization signal of another uninterruptible power supply becomes a predetermined value, the reference synchronization signal is generated. With this configuration, the period during which the PWM carrier synchronization signal of each of the plurality of uninterruptible power supply units has a predetermined value and the period during which the reference synchronization signal is generated can be overlapped. As a result, compared to the case where the period during which the PWM carrier synchronization signal of each of the plurality of uninterruptible power supply units has a predetermined value and the period during which the reference synchronization signal is generated do not overlap with each other, the A predetermined phase (for example, the central phase) of the period in which the PWM carrier synchronization signal of each of the uninterruptible power supply units has a predetermined value, and the predetermined phase (i.e., the central phase) of the period in which the reference synchronization signal is generated ) are relatively close to each other. Thereby, the phase difference between the PWM carrier synchronization signal and the reference synchronization signal of each of the plurality of uninterruptible power supplies (that is, the phase difference between the central phases) can be made relatively small. As a result, it is possible to easily adjust the phase of the PWM carrier synchronization signal to match the phase of the reference synchronization signal.

In the uninterruptible power supply system in which the control unit generates the reference synchronization signal, preferably each of the plurality of uninterruptible power supplies includes a first power path that supplies power from the inverter to the load, and the first power path is a second power path provided separately for supplying power from the outside to the load without passing through the converter and the inverter, and When synchronizing the phase of the inverter output voltage output from the inverter of the device and the phase of the bypass voltage externally input to each of the plurality of uninterruptible power supply devices via the second power path, the PWM carrier signal By correcting the frequency, control is performed to reduce each of the output voltage phase difference, which is the phase difference between the bypass voltage and the inverter output voltage, and the synchronization signal phase difference. With this configuration, it is possible to suppress cross currents (high frequency cross currents) from flowing between different uninterruptible power supply units by reducing the synchronization signal phase difference, and by decreasing the output voltage phase difference, When switching the power supply path to the load from the first power path to the second power path (or from the second power path to the first power path), a cross current (low-frequency cross current) occurs between the first power path and the second power path. ) can be suppressed from flowing. In addition, since the inverter output voltage of each of the plurality of uninterruptible power supplies is synchronized with the common bypass voltage, cross currents (low-frequency cross currents) can be suppressed between different uninterruptible power supplies.

In this case, preferably, the control unit of each of the plurality of uninterruptible power supplies controls the frequency of the inverter output voltage to the rated frequency when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized. In addition, it is configured to perform control to reduce the synchronization signal phase difference by correcting the frequency of the PWM carrier signal. According to this configuration, when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, the frequency of the inverter output voltage of each of the plurality of uninterruptible power supply systems is controlled to be the rated frequency. By reducing the signal phase difference, it is possible to suppress cross currents (high frequency cross currents) from flowing between different uninterruptible power supplies.

In the uninterruptible power supply system that performs control to reduce the synchronization signal phase difference when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, preferably, the control unit of each of the plurality of uninterruptible power supply units includes the inverter When the phase of the output voltage and the phase of the bypass voltage are not synchronized and the value of the synchronization signal phase difference is within the range of the dead band between the negative first value and the positive second value, PWM It is configured to perform control to set the correction amount of the frequency of the carrier signal to zero. With this configuration, when the synchronizing signal phase difference includes a small detection error within the range of the dead band, correction of the frequency of the PWM carrier signal based on the detection error can be suppressed. can.

In the uninterruptible power supply system that performs control to reduce each of the output voltage phase difference and the synchronization signal phase difference when synchronizing the phase of the inverter output voltage and the phase of the bypass voltage, preferably, a plurality of uninterruptible power supply units Each control unit has a proportional controller that performs at least proportional control using as an input value a value calculated by adding a value based on the synchronizing signal phase difference and the output voltage phase difference, and the phase of the inverter output voltage carrier frequency determination for determining the frequency of the PWM carrier signal by adding the output value of the proportional controller to the carrier frequency reference value that is the reference for the frequency of the PWM carrier signal when synchronizing the phase of the PWM carrier signal with the phase of the bypass voltage and is configured to correct the frequency of the PWM carrier signal based on the carrier frequency determination value. With this configuration, the frequency of the PWM carrier signal is corrected based on the carrier frequency determination value obtained by adding the output value of the proportional controller to the carrier frequency reference value. A value calculated by adding the value based on the phase difference and the output voltage phase difference is reduced by feedback control. As a result, the synchronizing signal phase difference and the output voltage phase difference can be easily reduced. Note that the proportional controller is realized by software such as a program.

In the uninterruptible power supply system that performs control to reduce each of the output voltage phase difference and the synchronization signal phase difference when synchronizing the phase of the inverter output voltage and the phase of the bypass voltage, preferably, a plurality of uninterruptible power supply units When the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, each control unit adds the output value from the low-pass filter to the value obtained by performing proportional control using the value based on the synchronizing signal phase difference as the input value. Based on the obtained value, it is configured to perform control for correcting the frequency of the PWM carrier signal. A value other than 0 is switched to 0 based on a change to a state to be released (for example, release when the bypass voltage is cut off). With this configuration, since the low-pass filter has a predetermined time constant, when the input value of the low-pass filter is switched from a value other than 0 to 0, the output value of the low-pass filter sharply decreases. change can be suppressed. As a result, it is possible to suppress a sudden change in the frequency of the PWM carrier signal, so that a sudden change in the frequency of the inverter output voltage can be suppressed even when a bypass voltage failure or the like occurs.

In the uninterruptible power supply system that performs control to reduce each of the output voltage phase difference and the synchronization signal phase difference when synchronizing the phase of the inverter output voltage and the phase of the bypass voltage, preferably, a plurality of uninterruptible power supply units Each control unit adjusts the output current value of its own uninterruptible power supply to a predetermined gain during the overlap period in which both the bypass voltage and the inverter output voltage of its own uninterruptible power supply are supplied to the load. Synchronization with the value obtained by performing proportional control using the 1st d-axis cross current component, which is the d-axis component of the difference between the multiplied value multiplied by and the output current value of the inverter of the uninterruptible power supply provided by itself, as an input value Control for correcting the frequency of the PWM carrier signal is performed based on the value obtained by adding the value obtained by proportional control using the value based on the signal phase difference as the input value. With this configuration, it is possible to reduce the first d-axis cross current component in addition to the synchronization signal phase difference during the overlap period. As a result, by reducing the synchronization signal phase difference in the overlap period, it is possible to suppress cross currents (high frequency cross currents) from flowing between different uninterruptible power supply apparatuses, and to reduce the first d-axis cross current component. Thus, it is possible to further suppress cross currents (low frequency cross currents) from flowing between the first power path and the second power path.

In the uninterruptible power supply system that performs control to reduce each of the output voltage phase difference and the synchronization signal phase difference when synchronizing the phase of the inverter output voltage and the phase of the bypass voltage, preferably, a plurality of uninterruptible power supply units each having a plurality of uninterruptible power supply sections each including a converter and an inverter, the control section of each of the plurality of uninterruptible power supply sections controlling the bypass voltage and the inverter output voltage in each of the plurality of uninterruptible power supply sections; The output voltage phase difference is calculated based on the difference from the average value. With this configuration, by calculating the output voltage phase difference using the average value of the inverter output voltage in each of the plurality of uninterruptible power supply units, the output voltage phase difference in each of the plurality of uninterruptible power supply units can be made equal. As a result, the frequencies of the corrected PWM carrier signals can be made equal in the different uninterruptible power supply units.

In the uninterruptible power supply system in which the control unit generates the reference synchronization signal, preferably, each control unit of the plurality of uninterruptible power supply units is provided with an average value of output current values of the plurality of uninterruptible power supply units and itself Proportional control is performed on the value obtained by performing proportional control with the input value of the second d-axis cross current component, which is the d-axis component of the difference from the output current value of the uninterruptible power supply, with the value based on the synchronization signal phase difference as the input value. It is configured to perform control for correcting the frequency of the PWM carrier signal based on the value obtained by adding the values obtained. With this configuration, the first d-axis cross current component can be reduced in addition to the synchronization signal phase difference. As a result, by reducing the synchronization signal phase difference, it is possible to suppress the flow of cross currents (high frequency cross currents) between different uninterruptible power supply devices, and by reducing the second d-axis cross current component, different Cross currents (low frequency cross currents) can be suppressed from flowing between the uninterruptible power supplies.

According to the present invention, as described above, it is possible to suppress an increase in size and cost of an uninterruptible power supply while suppressing a cross current from flowing between different uninterruptible power supplies.

It is a figure which shows the structure of the uninterruptible power supply system by 1st Embodiment. 4 is a diagram showing the configuration of phase difference control means of the control unit according to the first embodiment; FIG. FIG. 4 is a diagram showing synchronization signal phase differences according to the first embodiment; Fig. 3 shows a PWM carrier signal according to the first embodiment; 4 is a diagram showing the configuration of voltage command means of the control unit according to the first embodiment; FIG. It is a figure which shows the structure of the uninterruptible power supply system by 2nd Embodiment. It is a figure which shows the structure of the phase difference control means of the control part by 2nd Embodiment. It is a figure which shows the structure of the voltage command means of the control part by 2nd Embodiment. It is a figure which shows the structure of the uninterruptible power supply system by the modification of 1st Embodiment.

Embodiments embodying the present invention will be described below with reference to the drawings.

[First embodiment]
The configuration of an uninterruptible power supply system 100 according to the first embodiment will be described with reference to FIGS. 1 to 5. FIG.

(Configuration of uninterruptible power supply system)
First, the configuration of an uninterruptible power supply system 100 will be described with reference to FIG.

As shown in FIG. 1 , an uninterruptible power supply system 100 includes a plurality of uninterruptible power supplies 10 that are connected in parallel and supply power to a load 103 . A plurality of uninterruptible power supplies 10 have the same configuration as each other. In 1st Embodiment, the uninterruptible power supply system 100 shows the example containing three units|sets of the uninterruptible power supply 10a, the uninterruptible power supply 10b, and the uninterruptible power supply 10c.

Each of the plurality of uninterruptible power supplies 10 includes a first power path 11 that supplies power from an inverter 3 (to be described later) to a load 103 . Further, each of the plurality of uninterruptible power supplies 10 is provided separately from the first power path 11, and supplies power from the outside to the load 103 without passing through the converter 1 and the inverter 3 described later. Including 12.

Each of the plurality of uninterruptible power supplies 10 includes a converter 1 that converts AC power supplied from an AC power supply 101 into DC power. The AC power supplies 101 that supply AC power to each uninterruptible power supply 10 are different from each other. Alternatively, AC power may be supplied from a common AC power supply to each uninterruptible power supply 10 .

Further, each of the plurality of uninterruptible power supply devices 10 includes a chopper 2 that boosts DC power supplied from a power storage unit 102 that stores DC power.

Further, each of the plurality of uninterruptible power supply devices 10 includes an inverter 3 that converts DC power supplied from converter 1 or power storage unit 102 into AC power. Inverter 3 normally converts the DC power from converter 1 into AC power. Further, the inverter 3 converts the DC power sent from the power storage unit 102 via the chopper 2 into AC power in the event of an abnormality such as a power failure of the AC power supply 101 .

Each of the plurality of uninterruptible power supplies 10 also includes an inverter switch 4 that switches on and off the electrical connection between the inverter 3 and the load 103 .

Also, each of the plurality of uninterruptible power supplies 10 includes a bypass switch 5 . When the bypass switch 5 is on, the bypass voltage externally input to each of the plurality of uninterruptible power supplies 10 via the second power path 12 is applied to the load 103 via the bypass switch 5 . The bypass voltages input to each of the plurality of uninterruptible power supplies 10 are the same voltage (amplitude and phase).

Each of the plurality of uninterruptible power supplies 10 also includes a control unit 6 that generates a PWM carrier signal that serves as a reference for PWM signals that control the converter 1 and the inverter 3 . A PWM carrier signal is, for example, a triangular wave (see FIG. 4). The control unit 6 also has phase difference control means 60 and voltage command means 61 . Each function of phase difference control means 60 and voltage command means 61 can be realized by software such as a program. Further, the controllers 6 of the plurality of uninterruptible power supply units 10 communicate with each other (for example, wireless communication).

As shown in FIG. 2, the phase difference control means 60 includes a PI adjuster 60a, a dead zone processor 60b, a low pass filter 60c, P controllers 60d-60g, and switches 60h-60j. The PI controller 60a is an example of a "proportional controller" in the claims.

The control unit 6 of each of the plurality of uninterruptible power supplies 10 performs control to switch whether or not to synchronize the inverter output voltage output by the inverter 3 of the uninterruptible power supply 10 provided therein with the bypass voltage. Each of the switches 60h-60j is switched to the "T" side when synchronizing the inverter output voltage and the bypass voltage. Further, each of the switches 60h to 60j is switched to the "F" side when releasing the synchronization between the inverter output voltage and the bypass voltage.

Further, as shown in FIG. 3, the control unit 6 of each of the plurality of uninterruptible power supplies 10 generates a PWM carrier synchronization signal for synchronizing PWM carrier signals between different uninterruptible power supplies 10. . After the reference sine wave below changes from negative to 0 or positive to 0, the PWM carrier synchronization signal first rises to zero crossing where the count of the PWM carrier signal (see FIG. 4) changes from -1 to 0. (the first time point of one cycle of the PWM carrier signal), and rises to H after a predetermined time (see period A in FIG. 3) (eg, 400 μs) after falling to L. FIG.

Here, in the first embodiment, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 corrects the frequency of the PWM carrier signal based on the PWM carrier synchronization signal, Control to reduce the phase difference between PWM carriers, which is the phase difference between the PWM carrier signal of the uninterruptible power supply 10 provided by itself and the PWM carrier signal of another uninterruptible power supply 10, based on the PWM carrier synchronization signal configured to do so. That is, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 corrects the frequency of the PWM carrier signal based on the PWM carrier synchronization signal, so that the uninterruptible power supply 10 different from each other It is configured to perform control for synchronizing the PWM carrier signals between them.

Specifically, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 is provided with the PWM carrier synchronization signal of the uninterruptible power supply 10 itself and the other uninterruptible power supply 10 By correcting the frequency of the PWM carrier signal so as to reduce the phase difference with the PWM carrier synchronization signal, control is performed to reduce the phase difference between the PWM carriers. That is, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 is configured to perform control for synchronizing PWM carrier synchronization signals between different uninterruptible power supplies 10. ing.

Based on the PWM carrier signal whose frequency has been corrected, a three-phase reference sine wave that serves as a reference for the inverter output voltage command (a modulated wave that is multiplied by the inverter output voltage amplitude command and serves as a reference for the PWM signal together with the PWM carrier signal). ) is corrected. Specifically, during one period of the reference sine wave (with a rated frequency of 50 Hz, for example), the corrected PWM carrier signal is counted every half period. As a result, the period of the PWM carrier signal and the period of the reference sine wave are in a proportional relationship, and when the period of the PWM carrier signal changes, the period of the reference sine wave changes accordingly. Specifically, if the maximum count value is M and the number of counts is N, the corrected three-phase reference sine waves are sin(360deg×N/M) and sin(360deg×N/M− 120deg) and sin (360deg×N/M−240deg). Note that the count number is reset to 0 when the maximum value M is reached.

The control for synchronizing the PWM carrier synchronization signals will be described in detail. First, the control unit 6 of each of the plurality of uninterruptible power supplies 10 is based on the PWM carrier synchronization signal of the uninterruptible power supply 10 provided therein and the PWM carrier synchronization signal of the other uninterruptible power supply 10 A reference synchronization signal (see FIG. 3) is generated. The reference synchronization signals generated by each of the plurality of uninterruptible power supplies 10 are the same signal.

Here, in the first embodiment, by performing control to reduce the synchronization signal phase difference, which is the phase difference between the reference synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply 10 provided with itself, It is configured to perform control to reduce the phase difference between the PWM carrier synchronization signal of the uninterruptible power supply 10 that is selected and the PWM carrier synchronization signal of the other uninterruptible power supply 10 . Specifically, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supply units 10 controls a predetermined phase of the reference synchronization signal and a predetermined phase of its own PWM carrier synchronization signal. control to synchronize the As a result, the PWM carrier synchronization signals of the plurality of uninterruptible power supplies 10 are synchronized with each other based on the predetermined phase of the reference synchronization signal. Specifically, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 synchronizes the central phase of the reference synchronization signal with the central phase of its own PWM carrier synchronization signal. control. The PWM carrier synchronization signal of each of the plurality of uninterruptible power supplies 10 is an L active signal (the L state is the active state).

Further, in the first embodiment, the control unit 6 of each of the plurality of uninterruptible power supply devices 10 has a period A in which the PWM carrier synchronization signal of the uninterruptible power supply device 10 in which it is provided becomes a predetermined value, and other The reference synchronization signal is generated over a period B during which the PWM carrier synchronization signal of the uninterruptible power supply 10 becomes a predetermined value. Specifically, the control unit 6 generates a reference synchronization signal that is an OR signal of the PWM carrier synchronization signal of the uninterruptible power supply 10 provided with itself and the PWM carrier synchronization signal of the other uninterruptible power supply 10. Generate. When any one of the PWM carrier synchronization signals of each of the plurality of uninterruptible power supplies 10 is L (predetermined value), an L level OR signal (reference synchronization signal) is generated. As a result, in the example shown in FIG. 3, when the PWM carrier synchronization signal of the most advanced uninterruptible power supply 10a falls to L, the PWM carrier synchronization signal of the most delayed uninterruptible power supply 10c The OR signal (reference sync signal) is continuously at L level until it rises to H. Period A and period B are examples of "first period" and "second period" in the claims, respectively.

Next, control for reducing the synchronization signal phase difference will be described with reference to FIG.

(When synchronizing the inverter output voltage and the bypass voltage)
In the first embodiment, as shown in FIG. 2, when the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 synchronizes the phase of the inverter output voltage and the phase of the bypass voltage Furthermore, by correcting the frequency of the PWM carrier signal, control is performed to reduce each of the output voltage phase difference, which is the phase difference between the bypass voltage and the inverter output voltage, and the synchronization signal phase difference. . Specifically, a value calculated by adding a value based on the synchronizing signal phase difference (the output value of the P control unit 60d) and the output voltage phase difference is used as an input value, and at least proportional control is performed by the PI controller 60a. is done. Specifically, proportional control and integral control are performed by the PI adjuster 60a so that each of the synchronizing signal phase difference and the output voltage phase difference is reduced within a predetermined specified value range close to zero. is done. Note that the value based on the synchronizing signal phase difference is a value that is P-controlled (proportionally controlled) by the P control unit 60d using the synchronizing signal phase difference as an input value. A predetermined P gain (for example, 10) is used in the P control section 60d. The predetermined gain is set based on the difference between the magnitude of the synchronizing signal phase difference and the magnitude of the output voltage phase difference. The P gain used in the P control section 60f is also the same as the P gain used in the P control section 60d.

Note that the control unit 6 of each of the plurality of uninterruptible power supplies 10 detects the phase difference between the phase at which the bypass voltage is 0 V and the phase at which the inverter output voltage is 0 V, thereby detecting the output voltage phase difference. do.

Further, in the first embodiment, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 adjusts the output value of the PI adjuster 60a to the carrier frequency that is the reference for the frequency of the PWM carrier signal. By adding to the reference value, a carrier frequency determination value for determining the frequency of the PWM carrier signal is calculated, and the frequency of the PWM carrier signal is corrected based on the carrier frequency determination value. The carrier frequency determination value is the number of pulses (number of clocks) counted from 0 to the peak value of the PWM carrier signal. In the first embodiment, since the PWM carrier signal is a triangular wave, the carrier frequency determination value is the number of counts of 1/4 period (period C in FIG. 4) of the PWM carrier signal. Therefore, by correcting the carrier frequency determination value, the period and frequency of the PWM carrier signal are corrected.

Further, in the first embodiment, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supply devices 10 is provided with an average value of the output current values of the plurality of uninterruptible power supply devices 10 and itself. A value (output value of the P control unit 60e) obtained by proportional control using the d-axis cross current (active current component) between the UPSs, which is the d-axis component of the difference from the output current value of the power failure power supply 10, as an input value, It is configured to perform control for correcting the frequency of the PWM carrier signal based on a value obtained by adding a value (output value of the P control section 60d) obtained by performing proportional control using the synchronizing signal phase difference as an input value. The d-axis cross current between UPSs is the d-axis of the value obtained by converting the difference between the average value of the output current values of the plurality of uninterruptible power supply units 10 and the output current value of the uninterruptible power supply unit 10 in which it is provided. is an ingredient. The d-axis cross flow between UPSs is an example of the "second d-axis cross flow component" in the scope of claims.

Specifically, the first addition value is calculated by adding to the output voltage phase difference a value obtained by performing proportional control in the P control unit 60e using the inter-UPS d-axis cross current as an input value. Then, the second addition value is calculated by adding the first addition value and the value (the output value of the P control section 60d) that is proportionally controlled using the synchronization signal phase difference as the input value. By inputting the second addition value to the PI adjuster 60a, the carrier frequency determination value is corrected and the frequency of the PWM carrier signal is corrected.

In addition, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supply units 10 is configured so that both the bypass voltage and the inverter output voltage of the uninterruptible power supply unit 10 in which it is provided are supplied to the load 103. During the wrap period, proportional control is performed using a value based on the synchronizing signal phase difference as an input value (output value of the P control unit 60e) obtained by performing proportional control using the d-axis cross current (active current component) during bypass wrap as an input value. Control is performed to correct the frequency of the PWM carrier signal based on the value obtained by adding the value (the output value of the P control section 60d). That is, during the overlap period, the d-axis cross flow during bypass wrap is input to the P control unit 60e in addition to the inter-UPS d-axis cross flow. The d-axis cross flow during bypass wrap is an example of the "first d-axis cross flow component" in the scope of claims.

In addition, the d-axis cross current during bypass wrap is a multiplication value obtained by multiplying the output current value of the uninterruptible power supply 10 provided by itself by a predetermined gain in the overlap period, and the uninterruptible power supply 10 provided by itself is the d-axis component of the difference from the output current value of the inverter 3 of . Specifically, the d-axis cross current during bypass wrap is the d-axis component of the value obtained by 3-phase/dq-converting the difference between the multiplied value and the output current value during the overlap period.

Further, the predetermined gain is set to the above-mentioned It is changed from 1 to 0 with a predetermined slope during the overlap period. Further, the predetermined gain is changed from 0 to 1 with a predetermined slope during the overlap period when switching from bypass feeding to inverter feeding.

As shown in FIG. 5, the control unit 6 (voltage command means 61) generates a signal (inverter output voltage amplitude command in FIG. 5) containing information on the command value of the amplitude of the inverter output voltage. The voltage command means 61 includes a PI controller 61a and a P controller 61b.

The control unit 6 (voltage command means 61) controls a value based on an inverter output voltage amplitude command reference value, which serves as a reference for the command value of the amplitude of the inverter output voltage, and inverter output voltage amplitude detection, which is a detected value of the amplitude of the inverter output voltage. By using the difference from the value as an input value, proportional control and integral control are performed in the PI controller 61a. Then, the output of the PI controller 61a becomes the inverter output voltage amplitude command.

The value based on the inverter output voltage amplitude command reference value is the sum of the UPS q-axis cross current (reactive current component) and the q-axis cross current at bypass wrap (reactive current component) input to the inverter output voltage amplitude command reference value. It is a value obtained by adding a value (output value of the P control section 61b) to which proportional control is performed as a value. The UPS q-axis cross current is the q-axis component of the value obtained by three-phase/dq-converting the difference between the average value of the output current values of the plurality of uninterruptible power supply units 10 and the output current value of the uninterruptible power supply unit 10 provided therein. be. In addition, the q-axis cross current during the bypass wrap is obtained by multiplying the output current value of the uninterruptible power supply 10 provided by itself by a predetermined gain in the overlap period, and the uninterruptible power supply 10 provided by itself. It is the q-axis component of the value obtained by 3-phase/dq-converting the difference from the output current value of the inverter 3 . The predetermined gain is the same as in the case of the d-axis cross flow during bypass wrap. As a result, the q-axis cross current between different uninterruptible power supply devices 10 is reduced, and the q-axis cross current flowing between the inverter 3 and the bypass (between the first power path 11 and the second power path 12) is reduced. can be reduced.

(When the inverter output voltage and bypass voltage are not synchronized)
In the first embodiment, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10, when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, the frequency of the inverter output voltage is controlled to have an accuracy of ±0.01% with respect to the rated frequency, and control is performed to reduce the synchronization signal phase difference by correcting the frequency of the PWM carrier signal. Specifically, as shown in FIG. 2, when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, each of the switches 60h to 60j switches to the "F" side, so the output voltage phase difference is Only the sync signal phase difference, inter-UPS d-axis cross current, and bypass wrap d-axis cross current contribute to carrier frequency correction. Also, the rated frequency is, for example, a frequency of 50 Hz.

The control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10 controls the phase difference of the inverter output voltage when the phase of the bypass voltage is not synchronized and the value of the synchronization signal phase difference is negative. It is configured to perform control to set the correction amount of the frequency of the PWM carrier signal to 0 when it is within the range of the dead band between the first value (eg -5 μs) and the positive second value (eg 5 μs). ing. Specifically, when the value of the synchronization signal phase difference is within the dead zone between the first value and the second value, the output value of the dead zone processor 60b is zero. Note that the absolute value of the first value and the absolute value of the second value in the range of the dead band may be different from each other.

Also, if the value of the synchronization signal phase difference is greater than 5 μs (for example, P), the output value of the dead zone processor 60b will be P−5 μs. Also, if the value of the synchronizing signal phase difference is -5 μs or less (for example, N), the output value of the dead band processor 60b is N-(-5 μs). As a result, when the synchronization signal phase difference changes from a value within the dead band to a value outside the dead band, it is possible to suppress a sudden change in the output value of the dead band processor 60b. As a result, it is possible to suppress sudden changes in the frequency of the PWM carrier signal. The range of the dead band is set wider than the detection error range of the synchronization signal phase difference.

The control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supplies 10, when not synchronizing the phase of the inverter output voltage and the phase of the bypass voltage, the value based on the synchronization signal phase difference (dead band processing unit Control for correcting the frequency of the PWM carrier signal based on the value obtained by adding the output value from the low-pass filter 60c to the value (the output value of the P control unit 60f) that is proportionally controlled using the output value of 60b) as the input value. is configured to do

Specifically, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supply units 10 controls the output value of the P control unit 60f, the inter-UPS d-axis cross flow, and the d-axis cross flow during bypass wrap. A third addition value is calculated by adding the value output from the P control unit 60g to the addition value as an input value. Further, the control unit 6 (phase difference control means 60) of each of the plurality of uninterruptible power supply devices 10 adds the carrier frequency reference value, the third addition value, and the output value from the low-pass filter 60c, Calculate the carrier frequency determination value.

Here, in the first embodiment, the input value to the low-pass filter 60c changes from the state of synchronizing the phase of the inverter output voltage and the phase of the bypass voltage to the state of releasing the synchronization (for example, when the bypass voltage fails). It is switched from a non-zero value to a zero value based on what has been done. Specifically, the input value to the low-pass filter 60c is changed by switching the switch 60j based on the change from the state of synchronizing the phase of the inverter output voltage and the phase of the bypass voltage to the state of releasing the synchronization. , the output value of the PI controller 60a (value other than the above 0 value) is switched to the 0 value. Since the low-pass filter 60c has a predetermined time constant, it performs processing to gradually decrease the output after the 0 value is input. As a result, it is possible to perform continuous change processing in which the carrier frequency determination value gradually decreases. The integral term of the PI controller 60a is reset to 0 when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized. As a result, when the phase of the inverter output voltage and the phase of the bypass voltage are synchronized, it is possible to prevent the output of the PI controller 60a from becoming excessively large due to the integral term.

The control of the voltage command means 61 is the same as when the phase of the inverter output voltage and the phase of the bypass voltage are synchronized.

(Effect of the first embodiment)
The following effects can be obtained in the first embodiment.

In the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supplies 10 generates a PWM carrier synchronization signal for synchronizing PWM carrier signals between different uninterruptible power supplies 10. By correcting the frequency of the PWM carrier signal based on the PWM carrier synchronization signal, the PWM carrier signal of the uninterruptible power supply 10 provided with itself and the PWM carrier signal of the other uninterruptible power supply 10 The uninterruptible power supply system 100 is configured to perform control to reduce the phase difference between PWM carriers, which is the phase difference. As a result, even if the uninterruptible power supply 10 is not provided with an element such as a reactor to increase the impedance between the uninterruptible power supplies 10, the control unit 6 reduces the phase difference between the PWM carriers to generate a plurality of uninterruptible power supplies. By synchronizing the inverter output voltages of the power supply devices 10 , cross currents (high-frequency cross currents) flowing between the uninterruptible power supply devices 10 can be suppressed. As a result, the cross current (high frequency cross current) is suppressed by the control unit 6 provided in advance. It is possible to suppress the increase in size and cost of the uninterruptible power supply 10 while suppressing the cross current. In addition, even if the impedance between the uninterruptible power supply units 10 is small because the uninterruptible power supply units 10 are connected to each other by short wiring without using a reactor or the like, a cross current (high frequency cross current) is generated between the different uninterruptible power supply units 10. flow can be suppressed.

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supplies 10 is provided with the PWM carrier synchronization signal of the uninterruptible power supply 10 itself and other uninterruptible power supplies The uninterruptible power supply system 100 is configured to perform control to reduce the phase difference between PWM carriers by correcting the frequency of the PWM carrier signal so that the phase difference with the PWM carrier synchronization signal of 10 is reduced. Accordingly, by performing control to reduce the phase difference between the PWM carrier synchronization signals of the uninterruptible power supply devices 10 different from each other, the phase difference between PWM carriers can be easily reduced.

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supply devices 10 has the position of the reference synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply device 10 provided therein. By performing control to reduce the synchronization signal phase difference, which is the phase difference, the phase difference between the PWM carrier synchronization signal of the uninterruptible power supply 10 provided by itself and the PWM carrier synchronization signal of the other uninterruptible power supply 10 The uninterruptible power supply system 100 is configured to perform control to reduce. As a result, each of the plurality of uninterruptible power supplies 10 is a synchronization signal that is the phase difference between the reference synchronization signal that is the reference of the PWM carrier synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply 10 provided with itself. By reducing the phase difference, the PWM carrier synchronization signals of the plurality of uninterruptible power supplies 10 can be synchronized with each other based on the reference synchronization signal. As a result, the phase difference between the PWM carrier synchronization signals of the uninterruptible power supplies 10 different from each other can be easily reduced.

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supply units 10 is provided with the PWM carrier synchronization signal of the uninterruptible power supply unit 10 in which the period becomes a predetermined value The uninterruptible power supply system 100 is configured so as to generate a reference synchronization signal over a period A and a period B in which the PWM carrier synchronization signal of the other uninterruptible power supply 10 becomes a predetermined value. As a result, the period during which the PWM carrier synchronization signal of each of the plurality of uninterruptible power supplies 10 has a predetermined value and the period during which the reference synchronization signal is generated can be overlapped. As a result, compared to the case where the period during which the PWM carrier synchronization signal of each of the plurality of uninterruptible power supplies 10 has a predetermined value and the period during which the reference synchronization signal is generated do not overlap each other, A predetermined phase (for example, the central phase) of the period in which the PWM carrier synchronization signal of each of the plurality of uninterruptible power supplies 10 has a predetermined value, and the predetermined phase (that is, the central phase) of the period in which the reference synchronization signal is generated phase) are relatively close to each other. Thereby, the phase difference between the PWM carrier synchronization signal and the reference synchronization signal of each of the plurality of uninterruptible power supplies 10 (that is, the phase difference between the central phases) can be made relatively small. As a result, it is possible to easily adjust the phase of the PWM carrier synchronization signal to match the phase of the reference synchronization signal.

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supplies 10 is provided with the phase of the inverter output voltage output from the inverter 3 of the uninterruptible power supply 10 provided therein. When synchronizing the phase of the bypass voltage externally input to each of the plurality of uninterruptible power supplies 10 via the second power path 12, by correcting the frequency of the PWM carrier signal, the bypass voltage and the inverter The uninterruptible power supply system 100 is configured to perform control to reduce each of the output voltage phase difference, which is the phase difference with the output voltage, and the synchronization signal phase difference. As a result, by reducing the synchronization signal phase difference, it is possible to suppress the cross current (high frequency cross current) from flowing between the different uninterruptible power supply units 10, and by reducing the output voltage phase difference, the load 103 cross current between the first power path 11 and the second power path 12 when switching the power supply path from the first power path 11 to the second power path 12 (or from the second power path 12 to the first power path 11) (low-frequency cross current) can be suppressed. In addition, since the inverter output voltage of each of the plurality of uninterruptible power supply units 10 is synchronized with the common bypass voltage, it is possible to suppress cross currents (low-frequency cross currents) flowing between different uninterruptible power supply units 10. .

Further, in the first embodiment, as described above, when the control unit 6 of each of the plurality of uninterruptible power supplies 10 does not synchronize the phase of the inverter output voltage and the phase of the bypass voltage, the frequency of the inverter output voltage The uninterruptible power supply system 100 is configured to control so that the accuracy is ±0.01% with respect to the rated frequency, and to perform control to reduce the synchronization signal phase difference by correcting the frequency of the PWM carrier signal. do. As a result, when the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, the frequency of the inverter output voltage of each of the plurality of uninterruptible power supplies 10 has an accuracy of ±0.01% with respect to the rated frequency. It is possible to suppress cross currents (high frequency cross currents) from flowing between different uninterruptible power supply units 10 by reducing the synchronization signal phase difference while controlling to .

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supplies 10 does not synchronize the phase of the inverter output voltage and the phase of the bypass voltage. The uninterruptible power supply system performs control to set the correction amount of the frequency of the PWM carrier signal to 0 when the phase difference value is within the range of the dead zone between the negative first value and the positive second value 100. As a result, when the synchronization signal phase difference includes a small detection error within the dead band, it is possible to suppress correction of the frequency of the PWM carrier signal based on the detection error.

Further, in the first embodiment, as described above, when the control unit 6 of each of the plurality of uninterruptible power supplies 10 synchronizes the phase of the inverter output voltage and the phase of the bypass voltage, the PI controller 60a A carrier frequency determination value for determining the frequency of the PWM carrier signal is calculated by adding the output value to a carrier frequency reference value that is a reference for the frequency of the PWM carrier signal, and the PWM carrier signal is calculated based on the carrier frequency determination value. Configure uninterruptible power supply system 100 to compensate for frequency. As a result, the frequency of the PWM carrier signal is corrected based on the carrier frequency determination value obtained by adding the output value of the PI adjuster 60a to the carrier frequency reference value. and the output voltage phase difference are reduced by feedback control. As a result, the synchronizing signal phase difference and the output voltage phase difference can be easily reduced.

In the first embodiment, as described above, the input value to the low-pass filter 60c changes the phase of the inverter output voltage and the phase of the bypass voltage from the state of synchronizing to the state of releasing the synchronization (for example, when the bypass voltage fails). The uninterruptible power supply system 100 is configured to switch from a non-zero value to a zero value based on a change to a non-zero value. Accordingly, since the low-pass filter 60c has a predetermined time constant, when the input value of the low-pass filter 60c is switched from a value other than 0 to 0, the output value of the low-pass filter 60c changes sharply. can be suppressed. As a result, it is possible to suppress a sudden change in the frequency of the PWM carrier signal, so that a sudden change in the frequency of the inverter output voltage can be suppressed even when a bypass voltage failure or the like occurs.

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supplies 10 sets the output current value of the uninterruptible power supply 10 provided therein to a predetermined value during the overlap period. Proportional control was performed using the d-axis cross current during bypass wrap, which is the d-axis component of the difference between the multiplied value multiplied by the gain and the output current value of the inverter 3 of the uninterruptible power supply 10 provided therein, as an input value. The uninterruptible power supply system 100 is configured to perform control to correct the frequency of the PWM carrier signal based on the value obtained by adding the value obtained by performing proportional control using the value based on the synchronization signal phase difference as the input value. do. As a result, in the overlap period, the d-axis cross current during bypass wrap can be reduced in addition to the synchronization signal phase difference. As a result, by reducing the synchronization signal phase difference during the overlap period, cross currents (high frequency cross currents) can be suppressed between different uninterruptible power supply units 10, and d-axis cross currents can be suppressed during bypass wrap. By reducing the size, it is possible to further suppress the cross current (low frequency cross current) from flowing between the first power path 11 and the second power path 12 .

Further, in the first embodiment, as described above, the control unit 6 of each of the plurality of uninterruptible power supply devices 10, the average value of the output current values of the plurality of uninterruptible power supply devices 10 and the uninterruptible power supply provided with itself Proportional control was performed on a value obtained by performing proportional control using the d-axis cross current between UPSs, which is the d-axis component of the difference from the output current value of the device 10, as an input value, and using a value based on the synchronization signal phase difference as an input value. The uninterruptible power supply system 100 is configured to perform control for correcting the frequency of the PWM carrier signal based on the added value. As a result, the d-axis cross current between UPSs can be reduced in addition to the synchronization signal phase difference. As a result, by reducing the synchronization signal phase difference, it is possible to suppress the flow of cross currents (high frequency cross currents) between different uninterruptible power supply units 10, and by reducing the d-axis cross currents between UPSs, Cross currents (low-frequency cross currents) flowing between different uninterruptible power supply units 10 can be suppressed.

[Second embodiment]
A second embodiment will be described with reference to FIGS. 6 to 8. FIG. In this second embodiment, unlike the first embodiment, each of the plurality of uninterruptible power supply units 10 is provided with a plurality of uninterruptible power supply modules 111 . In the figure, the same reference numerals are given to the same configurations as those of the first embodiment, and the description thereof will be omitted.

(Configuration of uninterruptible power supply system)
First, the configuration of the uninterruptible power supply system 200 will be described with reference to FIG.

As shown in FIG. 6 , the uninterruptible power supply system 200 includes a plurality of uninterruptible power supplies 110 that are connected in parallel and supply power to the load 103 . A plurality of uninterruptible power supplies 110 have the same configuration as each other. In 2nd Embodiment, the uninterruptible power supply system 200 shows the example containing three units|sets of the uninterruptible power supply 110a, the uninterruptible power supply 110b, and the uninterruptible power supply 110c.

Each of the plurality of uninterruptible power supplies 110 has a plurality of uninterruptible power supply modules 111 each including a converter 1 and an inverter 3 . As a result, even if one (or two) of the uninterruptible power supply modules 111 in the uninterruptible power supply 110 fails or is stopped for parts replacement, etc., the remaining normal uninterruptible power supply modules 111 can be used. can supply power to the load 103. Also, by switching the number of uninterruptible power supply modules 111 to be operated according to the size of the load 103, it is possible to improve the efficiency of power supply. Also, each of the plurality of uninterruptible power supply modules 111 has a chopper 2 and an inverter switch 4 in addition to the converter 1 and the inverter 3 . Also, each of the plurality of uninterruptible power supplies 110 includes a first power path 11 and a second power path 12 . The first power path 11 is provided in each of the plurality of uninterruptible power supply modules 111 . The uninterruptible power supply module 111 is an example of an "uninterruptible power supply unit" in the scope of claims.

Also, in each of the plurality of uninterruptible power supply devices 110 , AC power is supplied from a common AC power supply 101 to the plurality of uninterruptible power supply modules 111 . Also, in each of the plurality of uninterruptible power supply devices 110 , DC power is supplied from a common power storage unit 102 to the plurality of uninterruptible power supply modules 111 .

Also, each of the plurality of uninterruptible power supplies 110 includes a control unit 16 . Also, the control unit 16 is configured to control each of the plurality of uninterruptible power supply modules 111 in each of the plurality of uninterruptible power supply devices 110 . The control unit 16 has phase difference control means 160 and voltage command means 161 . Each function of phase difference control means 160 and voltage command means 161 can be implemented by software such as a program.

Here, in the second embodiment, as shown in FIG. 7, the control unit 16 (phase difference control means 160) of each of the plurality of uninterruptible power supply units 110 controls the bypass voltage and the The output voltage phase difference is calculated based on the difference from the average value of the inverter output voltage in each. Specifically, the controller 16 of each of the plurality of uninterruptible power supplies 110 generates a reference sine wave whose frequency is corrected based on a predetermined rated frequency (50 Hz). The method of correcting the reference sine wave based on the PWM carrier signal is the same as in the first embodiment. The output voltage phase difference is a value obtained by adding an average value of phase differences between the phase of the reference sine wave and the phase of the inverter output voltage to the phase difference between the bypass voltage and the reference sine wave. As a result, an output voltage phase difference, which is a phase difference between the bypass voltage and the inverter output voltage, is detected. The average value of the phase difference between the phase of the reference sine wave and the phase of the inverter output voltage is the average value of the phase difference between the phase of the reference sine wave and the phase of the inverter output voltage of each of the plurality of uninterruptible power supply modules 111. means value. Also, the reference sine wave is common to each uninterruptible power supply module 111 in each of the plurality of uninterruptible power supply systems 110 .

The d-axis cross current during bypass wrap in the second embodiment is the difference between the product of the output current detection value of the uninterruptible power supply 110 and a predetermined gain and the total output current value of the plurality of uninterruptible power supply modules 111. It is the d-axis component of the value after 3-phase/dq conversion. Note that the predetermined gain is the same as in the first embodiment.

In addition, the q-axis cross current during bypass wrap used in the voltage command means 161 shown in FIG. It is the q-axis component of the value obtained by 3-phase/dq-converting the difference from the current total value. Note that the predetermined gain is the same as in the first embodiment.

Further, the difference between a value obtained by adding the output value of the P control section 61b to the inverter output voltage amplitude command reference value and the average value of the inverter output voltage amplitude detection values is input to the PI controller 61a. The average value of the inverter output voltage amplitude detection values means the average value of the output voltage amplitude detection values of the inverters 3 of the plurality of uninterruptible power supply modules 111 that are not stopped. In addition, each of the plurality of uninterruptible power supply modules 111 may be provided with a control unit having a voltage command means for performing the above control. In this case, the voltage command means uses the output voltage amplitude detection value of the inverter 3 of each uninterruptible power supply module 111 instead of using the average value of the inverter output voltage amplitude detection value in the voltage command means 161. An inverter output voltage amplitude command for the power failure power supply module 111 is output.

Other configurations of the second embodiment are the same as those of the first embodiment.

(Effect of Second Embodiment)
The following effects can be obtained in the second embodiment.

In the second embodiment, the control unit 16 of each of the plurality of uninterruptible power supply devices 110 determines the output voltage based on the difference between the bypass voltage and the average value of the inverter output voltages of each of the plurality of uninterruptible power supply modules 111. The uninterruptible power supply system 200 is configured to calculate the phase difference. By calculating the output voltage phase difference using the average value of the inverter output voltage in each of the plurality of uninterruptible power supply modules 111, the output voltage phase differences in each of the plurality of uninterruptible power supply modules 111 are made equal to each other. be able to. As a result, the frequencies of the corrected PWM carrier signals can be made equal in the uninterruptible power supply modules 111 different from each other.

Other effects of the second embodiment are the same as those of the first embodiment.

[Modification]
The embodiments disclosed this time should be considered illustrative and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and includes all modifications (modifications) within the scope and meaning equivalent to the scope of the claims.

For example, in the above-described first embodiment, an example in which the power storage units 102 corresponding to each of the plurality of uninterruptible power supply units 10 are provided separately from each other was shown, but the present invention is not limited to this. A common power storage unit may be provided for each of the plurality of uninterruptible power supplies 10 . For example, as shown in FIG. 9 , each of the plurality of uninterruptible power supply devices 10 of the uninterruptible power supply system 300 is supplied with DC power from a common power storage unit 202 . In this case, by using the PWM carrier signal controlled to synchronize between the mutually different uninterruptible power supply devices 10 in generating the PWM signal for controlling the chopper 2, the choppers 2 of the mutually different uninterruptible power supply devices 10 It is possible to suppress high-frequency cross currents from flowing between them. Note that the second embodiment may also be configured in the same manner. In addition, in the case of a configuration in which AC power is supplied from a common AC power supply 101 to each uninterruptible power supply 10, high-frequency cross currents are suppressed from flowing between converters 1 of mutually different uninterruptible power supplies 10. It is possible. The same applies to the second embodiment.

Further, in the first and second embodiments, the control unit 6 (16) of each of the plurality of uninterruptible power supply devices 10 (110) controls the reference synchronization signal and the PWM carrier of its own uninterruptible power supply device 10 (110). Although an example of performing control to reduce the phase difference (synchronization signal phase difference) with the synchronization signal has been shown, the present invention is not limited to this. Each control unit 6 (16) of a plurality of uninterruptible power supply 10 (110), without using the reference synchronization signal, the PWM carrier synchronization signal of its own uninterruptible power supply 10 (110), other uninterruptible power supply Control may be performed to directly reduce the phase difference with the PWM carrier synchronization signal of the power failure power supply 10 (110).

Further, in the first and second embodiments, the control unit 6 (16) of each of the plurality of uninterruptible power supply devices 10 (110) controls the central phase of the reference synchronization signal and the uninterruptible power supply device 10 (110) ) is controlled to reduce the phase difference (synchronization signal phase difference) from the center phase of the PWM carrier synchronization signal, but the present invention is not limited to this. The control unit 6 (16) of each of the plurality of uninterruptible power supplies 10 (110) controls a predetermined phase other than the center of the reference synchronization signal (for example, the phase at which the reference synchronization signal falls to L) and its own uninterruptible power supply Control may be performed to reduce the phase difference with a predetermined phase other than the center of the PWM carrier synchronization signal of 10 (110) (for example, the phase at which the PWM carrier synchronization signal falls to L).

Further, in the first and second embodiments, the control unit 6 (16) of each of the plurality of uninterruptible power supplies 10 (110) is provided for the PWM carrier synchronization of the uninterruptible power supply 10 (110) itself. Although an example of generating a reference synchronization signal that is an OR signal of a signal and a PWM carrier synchronization signal of another uninterruptible power supply 10 (110) has been shown, the present invention is not limited to this. The control unit 6 (16) of each of the plurality of uninterruptible power supplies 10 (110) is provided with the PWM carrier synchronization signal of the uninterruptible power supply 10 (110) provided therein, and the other uninterruptible power supply 10 (110 ) and the PWM carrier synchronizing signal may be generated as a reference synchronizing signal which is an AND signal. In this case, the reference synchronizing signal and each PWM carrier synchronizing signal are H active (H state is active state) signals.

Further, in the first and second embodiments, the control unit 6 (16) of each of the plurality of uninterruptible power supplies 10 (110) performs control to reduce each of the output voltage phase difference and the synchronization signal phase difference. Although an example has been given, the invention is not so limited. The control unit 6 (16) of each of the plurality of uninterruptible power supplies 10 (110) may perform control to reduce the synchronization signal phase difference without performing control to reduce the output voltage phase difference.

Further, in the above-described first and second embodiments, an example in which the control unit 6 (16) is provided with the dead zone processing unit 60b was shown, but the present invention is not limited to this. The dead band processor 60b may not be provided in the controller 6 (16).

Further, in the first and second embodiments, when the input value of the dead zone processing section 60b is outside the range of the dead zone, the dead zone processing section 60b outputs the difference between the input value and the range of the dead zone. , the present invention is not limited to this. When the input value of the dead zone processor is outside the range of the dead zone, the dead zone processor may output the input value as it is.

Further, in the first and second embodiments, an example in which the PI controller 60a (proportional controller) for performing proportional control and integral control is provided in the control section 6 (16) was shown, but the present invention is limited to this. can't Instead of the PI controller 60a, the controller 6 (16) may be provided with a PID controller that performs differential control in addition to proportional control and integral control.

Moreover, in the first and second embodiments, an example in which three uninterruptible power supplies 10 (110) are connected in parallel has been shown, but the present invention is not limited to this. Two or four or more uninterruptible power supplies 10 (110) may be connected in parallel. In the second embodiment, each uninterruptible power supply 110 may be provided with two or four or more uninterruptible power supply modules 111 .

Further, in the above-described first and second embodiments, an example in which each uninterruptible power supply 10 (110) is provided with one control unit 6 (16) is shown, but the present invention is not limited to this. A plurality of control units may be provided in each uninterruptible power supply 10 (110). Further, in the second embodiment, each uninterruptible power supply module 111 may be provided with a control unit.

1 converter 3 inverter 6, 16 controller 10, 10a, 10b, 10c, 110, 110a, 110b, 110c uninterruptible power supply 11 first power path 12 second power path 60a PI controller (proportional controller)
60c Low-pass filter 100, 200, 300 uninterruptible power supply system 101 AC power supply 102, 202 power storage unit 103 load 111 uninterruptible power supply module (uninterruptible power supply unit)
A period (first period)
Period B (second period)

Claims (12)

comprising a plurality of uninterruptible power supplies connected in parallel with each other and supplying power to the loads;
Each of the plurality of uninterruptible power supplies includes a converter that converts AC power supplied from an AC power source into DC power, and a DC power that is supplied from the converter or a power storage unit that stores the DC power, and converts the DC power into AC power. an inverter, and a control unit that generates a PWM carrier signal that serves as a reference for the PWM signal that controls the converter and the inverter,
The control unit of each of the plurality of uninterruptible power supplies generates a PWM carrier synchronization signal for synchronizing the PWM carrier signals between the different uninterruptible power supplies, and the PWM carrier synchronization signal PWM carrier which is the phase difference between the PWM carrier signal of the uninterruptible power supply to which it is provided and the PWM carrier signal of the other uninterruptible power supply by correcting the frequency of the PWM carrier signal based on An uninterruptible power supply system that is configured to provide control to reduce the interphase difference. The control unit of each of the plurality of uninterruptible power supply systems has a phase difference between the PWM carrier synchronization signal of the uninterruptible power supply system provided therein and the PWM carrier synchronization signal of the other uninterruptible power supply systems. 2 . The uninterruptible power supply system according to claim 1 , wherein control is performed to reduce the phase difference between the PWM carriers by correcting the frequency of the PWM carrier signal so as to reduce . The control unit of each of the plurality of uninterruptible power supplies is based on the PWM carrier synchronization signal of the uninterruptible power supply provided therein and the PWM carrier synchronization signal of the other uninterruptible power supply. By generating a reference synchronization signal and performing control to reduce the synchronization signal phase difference, which is the phase difference between the reference synchronization signal and the PWM carrier synchronization signal of the uninterruptible power supply provided with itself, 3. Control is performed to reduce a phase difference between the PWM carrier synchronization signal of the provided uninterruptible power supply and the PWM carrier synchronization signal of the other uninterruptible power supply. Uninterruptible power system as described. The control unit of each of the plurality of uninterruptible power supplies includes a first period in which the PWM carrier synchronization signal of the uninterruptible power supply provided therein becomes a predetermined value, and a period of the other uninterruptible power supplies. 4. The uninterruptible power supply system according to claim 3, wherein said reference synchronizing signal is generated over a second period in which said PWM carrier synchronizing signal becomes said predetermined value. Each of the plurality of uninterruptible power supply devices is provided separately from a first power path that supplies power from the inverter to the load and the first power path, and receives power from the outside through the converter and the inverter. a second power path that supplies the load without passing through
The control unit of each of the plurality of uninterruptible power supply devices provides the phase of the inverter output voltage output from the inverter of the uninterruptible power supply device in which it is provided and the second When synchronizing the phase of the bypass voltage input from the outside through the power path, the output voltage, which is the phase difference between the bypass voltage and the inverter output voltage, is corrected by correcting the frequency of the PWM carrier signal. The uninterruptible power supply system according to claim 3 or 4, configured to perform control to reduce each of the phase difference and the synchronization signal phase difference. When the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, the control unit of each of the plurality of uninterruptible power supplies controls the frequency of the inverter output voltage to become the rated frequency, and 6. The uninterruptible power supply system according to claim 5, wherein control is performed to reduce said synchronization signal phase difference by correcting the frequency of said PWM carrier signal. When the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, and the value of the synchronization signal phase difference is from a negative first value, the control unit of each of the plurality of uninterruptible power supply units 7. The uninterruptible power supply according to claim 6, configured to perform control to set the correction amount of the frequency of the PWM carrier signal to 0 when it is within the range of the dead band between up to the positive second value. system. The control unit of each of the plurality of uninterruptible power supply units performs at least proportional control using, as an input value, a value calculated by adding a value based on the synchronization signal phase difference and the output voltage phase difference. When a controller is provided and the phase of the inverter output voltage and the phase of the bypass voltage are synchronized, the output value of the proportional controller is added to the carrier frequency reference value that is the reference of the frequency of the PWM carrier signal. and calculating a carrier frequency determination value for determining the frequency of the PWM carrier signal, and correcting the frequency of the PWM carrier signal based on the carrier frequency determination value. The uninterruptible power supply system according to any one of . When the phase of the inverter output voltage and the phase of the bypass voltage are not synchronized, the control unit of each of the plurality of uninterruptible power supply units performs proportional control using a value based on the synchronization signal phase difference as an input value. Based on the value obtained by adding the output value from the low-pass filter to the value obtained, control is performed to correct the frequency of the PWM carrier signal,
The input value to the low-pass filter is changed from a non-zero value to a zero value based on the change from the state of synchronizing the phase of the inverter output voltage and the phase of the bypass voltage to the state of releasing the synchronization. An uninterruptible power supply system according to any one of claims 5 to 8 which is switched. The control unit of each of the plurality of uninterruptible power supplies is provided during an overlap period in which both the bypass voltage and the inverter output voltage of the uninterruptible power supply to which it is provided are supplied to the load. The 1d-axis component of the difference between the multiplied value obtained by multiplying the output current value of the uninterruptible power supply provided by a predetermined gain and the output current value of the inverter of the uninterruptible power supply provided therein The frequency of the PWM carrier signal is corrected based on a value obtained by adding a value obtained by performing proportional control using the value based on the phase difference of the synchronization signal as an input value to a value obtained by performing proportional control using the axial cross-flow component as an input value. The uninterruptible power supply system according to any one of claims 5 to 9, wherein the control is performed. each of the plurality of uninterruptible power supply units has a plurality of uninterruptible power supply units each including the converter and the inverter;
The control unit of each of the plurality of uninterruptible power supply units adjusts the output voltage phase difference based on the difference between the bypass voltage and the average value of the inverter output voltage in each of the plurality of uninterruptible power supply units. An uninterruptible power supply system according to any one of claims 5 to 10, configured to calculate. The control unit of each of the plurality of uninterruptible power supply units controls the difference between the average value of the output current values of the plurality of uninterruptible power supply units and the output current value of the uninterruptible power supply unit in which it is provided. Based on the sum of the value obtained by performing proportional control using the value based on the synchronization signal phase difference as an input value and the value obtained by performing proportional control using the second d-axis cross current component, which is an axial component, as an input value, the PWM The uninterruptible power supply system according to any one of claims 3 to 11, configured to perform control for correcting the frequency of the carrier signal.

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