JP2013106368A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device that can supply power from an input system even when a phase rotation of a commercial power supply is different.SOLUTION: The DC output type power conversion device having a converter 10 for converting AC power supplied from a commercial power supply 7 to DC power, a current control circuit 20 for creating an output voltage command for the converter 10 such that a current to the converter 10 matches a current amplitude standard, and a gate control circuit 27 for controlling a gate of a switching element constituting the converter 10 on the basis of the output command for the converter 10 from the current control circuit 20 includes: a phase rotation fault detection circuit 51 for detecting a phase rotation fault in the commercial power supply 7; and a circuit for changing an input to a converter control circuit 14 and a converter gate output on the basis of an output of the phase rotation fault detection circuit 51.

Description

  The present embodiment relates to a power conversion device that converts AC power from a commercial power source into power and converts it to a load.

  A conventional uninterruptible power supply includes a converter that converts AC power supplied from a commercial power source through an AC filter into DC power, and an inverter that converts DC power converted by the converter into AC power and supplies the load to a load. A storage battery connected to the input side of the inverter, a switching circuit for switching the power supply to the load to either the commercial power source side or the inverter side, and the output voltage of the converter so that the converter current matches the current amplitude reference Current control means for creating a command, and a gate control circuit for controlling the gate of the switching element constituting the converter based on the converter output command from the current control means.

  And normally, it converts into a desired direct-current voltage source from a commercial power source with a converter, and the inverter which inputs this direct-current voltage source outputs a desired voltage, and power supply from a power converter to a load is performed.

  In the event of an AC input error such as an AC input power failure, the converter is stopped by detecting an AC input error, supplying power to the inverter from a DC voltage source that can be configured like a storage battery, and continuing to supply power to the load To do.

JP 2002-27684 A

  However, in the conventional power converter, if the phase rotation of the commercial power supply is different due to, for example, different wiring connection, the converter control system becomes unstable and the DC constant voltage control function and the input power factor “1” cannot be maintained. Therefore, the inverter power supply was continued using the DC power supply as an input when the device was protected from protection or had a DC power supply.

  For this reason, DC operation is continued from the viewpoint of device protection in the state of abnormal phase rotation despite the state of having an energy as an AC power source. Sometimes stopped.

  The present embodiment has been made to eliminate the above-described drawbacks, and an object thereof is to provide a power conversion device that can supply power from an input system even when the commercial power supply has different phase rotations.

  A typical power conversion device of an embodiment creates a converter that converts AC power supplied from a commercial power source into DC power, and an output voltage command of the converter so that the current of the converter matches a current amplitude reference. In a DC output type power converter having a current control means and a gate control circuit for controlling a gate of a switching element constituting the converter based on a converter output command from the current control means, phase rotation of the commercial power supply And a circuit for changing the input of the converter control circuit and the converter gate output by the output of the phase rotation detection circuit.

  According to the representative power converter of the embodiment, it is possible to supply power from the input system even if the commercial power supply has a different phase rotation.

The block diagram which shows the structure of the power converter device in this embodiment. The block diagram for demonstrating the converter control circuit of FIG. The figure for demonstrating the phase rotation abnormality detection circuit of FIG. The figure for demonstrating the main circuit of the converter of FIG. The figure for demonstrating the DC voltage control circuit of FIG. The figure for demonstrating the alternating current detection circuit of FIG. The figure for demonstrating the gate control circuit of FIG. The figure for demonstrating operation | movement of the alternating current detection circuit of FIG. The figure for demonstrating operation | movement of the input current control circuit of FIG. The figure for demonstrating operation | movement of the phase rotation abnormality detection circuit of FIG. The figure for demonstrating operation | movement of the phase rotation abnormality detection circuit of FIG.

  FIG. 1 shows a first example of the power converter of this embodiment. The output of the inverter 1 is connected to the primary winding of the inverter transformer 2, and the secondary winding of the inverter transformer 2 is connected to the power converter. And is connected to the switching circuit 3. The switching circuit 3 includes a contactor 4 and a semiconductor switch 5, and uses the power supply to the load 6 to switch between the power converter and the commercial power source 7.

  Here, the switching circuit 3 includes the contactor 4 and the semiconductor switch 5, but only one of them may be used. Further, a configuration without the inverter transformer 2 may be used.

  On the input side of the inverter 1, AC power from the commercial power supply 7 is input via the AC filter 8 and the grid connection reactor 9, and a converter 10 that outputs DC power, and a DC that smoothes the output of the converter 10. A capacitor 11 and a storage battery 12 serving as a voltage source when an AC input abnormality such as an AC input power failure occurs are connected. The AC filter 8 is provided in order to prevent the harmonic generated in the converter 10 from being regenerated in the commercial power supply 7.

  And normally, the AC power to the load 6 is converted to a desired DC voltage source by the converter 10 from the commercial power source 7 and the inverter 1 having the DC voltage source as an input outputs a desired AC voltage. Is fed.

  When an AC input abnormality such as an AC input power failure occurs, the converter 10 is stopped by detecting an abnormality of the AC input, and power to the inverter 1 is supplied from what can constitute a DC voltage source such as the storage battery 12 to the load 6. Continue to supply power.

  Next, the converter control circuit 14 will be described with reference to FIG.

  A DC voltage detection signal 16, which is an output of a DC voltage detector 13 that measures a DC voltage such as a DC capacitor, is input to the converter control circuit 14, and is supplied as a DC voltage feedback to the DC voltage control circuit 15 in the converter control circuit 14. Entered. The converter control circuit 14 is connected to a power failure detection circuit 18 and a PLL circuit 19 that detect an AC input abnormality such as an AC input power failure based on the output of the AC voltage detection circuit 17 that detects an AC input voltage.

  Signals described below are input to the input of the input current control circuit 20. That is, the input current amplitude reference 21 that is the output of the DC voltage control circuit 15 is the converter reference phase 22 that is the output of the PLL circuit 19, and the input voltage detection signal 23 of the AC voltage detector 17 is the input voltage feedback. The input current detection signal 24 of the current detector 25 is input as feedback.

  An input voltage command 26 obtained in the input current control circuit 20 is input to the gate control circuit 27, and a power failure detection signal 29 and a converter phase order switching signal described later are input to the gate control circuit 27. The required gate signal 28 of the converter 10 is output.

  In FIG. 2, the DC voltage control circuit 15 outputs an input current amplitude reference 21 so that the inverter can output an output corresponding to the voltage that the power converter should originally output. The input current control circuit 20 performs control so that the input current detection signal 24 detected by the current detector 25 is equal to the input current amplitude reference 21 and the converter reference phase 22 detected by the PLL circuit 19. An input voltage command 26 is output. The gate control circuit 27 outputs a gate signal 28 so that the output of the converter 10 matches the input voltage command 26.

  The converter control circuit 14 described above is provided with a phase rotation abnormality detection circuit 51 described below. The phase rotation abnormality detection circuit 51 receives an input voltage detection signal (AC input voltage, converter input) 23 that is an output from the AC voltage detection circuit 17 and an input voltage sound signal 57 from the power failure detection circuit 18, and a phase rotation abnormality is detected. The detection circuit 51 receives a converter phase order switching signal 52 as an output to the input current control circuit 20 and the gate control circuit 27, respectively.

  FIG. 3 shows a specific example of the phase rotation abnormality detection circuit 51, which comprises a D latch circuit 53 and an AND circuit 58. The D latch circuit 53 is connected to the clock input terminal CLK at the timing of the clock signal 54. If there is an input signal 55, the latch output is not output from the output terminal Q, and the latch output is output from the output terminal Q in other cases. The D latch input 55 and the clock input 54 are obtained from the input voltage detection signal 23 as described later, and the D latch output 56 and the input voltage sound signal 57 of the D latch circuit 53 are input to the AND circuit 58. As a result, when both the D latch output 56 and the input voltage sound signal 57 exist, the converter phase order change signal 52 is obtained as an output from the AND circuit 58.

  Here, one a phase (for example, U phase) of the input voltage detection signal 23 is input as the clock input 54 of the D latch circuit 53, and another b phase (for example, V phase if the above phase is U phase) Phase) is the D latch input 55. Thereby, it is detected that the U phase and V phase of the AC input voltage are within a predetermined time (phase), and when the predetermined time is exceeded (in this configuration, 180 degrees: 50 ms, 10 ms) That is, when it is detected that the phase sequence of the AC input voltage is not correct, the output 56 of the D latch circuit is turned on. The D latch output 56 and the input voltage sound signal 57 that is the output of the power failure detection circuit 18 are input to the logical product circuit 58, and the output of the logical product circuit 58 is the converter phase order replacement signal 52.

  Moreover, although the converter 10 of FIG. 1 is provided with a charging current control circuit (not shown) for charging the storage battery 12, the description thereof is omitted here.

  Similarly to the converter control circuit 14 of the converter 10, an inverter control circuit (not shown) is also provided for the inverter 1.

  FIG. 4 shows a main circuit of the converter 10, and an arm such as the following elements is bridge-connected, a commercial power supply 7 is connected to the input side, and a positive electrode P and a negative electrode N are provided on the output side. . Collectors of switching elements 31a, 31c, and 31e are connected to the positive electrode P, and diodes 32a, 32c, and 32e are connected in antiparallel to the switching elements. Collectors of switching elements 31b, 31d, and 31f are connected to the negative electrode N, and diodes 32b, 32d, and 32f are connected in antiparallel to the switching elements. A DC capacitor 11 is connected between the positive electrode P and the negative electrode N, and a converter output 33 is obtained from both ends of the positive electrode P and the negative electrode N and the DC capacitor 11.

  A gate signal 28 is input to the gate drive circuit 34. Each switching element 32 is provided with a snubber circuit for suppressing a surge voltage during switching individually or collectively, but is omitted here for the sake of simplicity. In response to the gate signal 28, the gate driving circuit 34 generates a dead time that prevents switching elements connected in series, for example, 31a and 31b, from turning on at the same time, and the charge / discharge period of each snubber circuit Or to secure. The converter 10 charges the storage battery 12 as a power storage element by controlling the DC voltage of the DC capacitor 11 by pulse width modulation (PWM).

  FIG. 5 is a configuration example of the DC voltage control circuit 15 in the converter control circuit 14. The DC voltage command (DC voltage reference signal) 35 outputs a constant voltage command so that the inverter 1 can output a desired voltage. A circuit for setting various DC voltage commands may be provided in accordance with the characteristics of the storage battery 12 that is a power storage element, but is omitted here for the sake of simplicity.

  A difference between the DC voltage command 35 and the DC voltage detection signal 16 from the DC voltage detector 13 is obtained by a difference detector 37, and this difference is input to the PI control circuit 36 and input as an output of the PI control circuit 36. A current amplitude reference 21 is obtained.

  In this example, PI control is used as voltage control, but it goes without saying that it may be a control circuit using PID control, IP control, other general control methods, modern control theory, or the like.

  FIG. 6 is a configuration example of the input current control circuit 20 in the converter control circuit 14. The input current amplitude reference 21 and the converter reference phases 22a to 22c which are the outputs of the PLL circuit 19 are connected to multipliers 41a to 41c. The outputs of the multipliers 41a to 41c serve as U-phase, V-phase, and W-phase AC input current references. A difference from the input current detection signal 24 is taken for each AC input current reference, and each difference is input to the P control circuits 42a to 42c.

  In FIG. 6, P control circuits 42a to 42c perform control so that the input current detection signal 24 follows the input current reference. In this example, the P control is used as the voltage control, but it goes without saying that a control circuit using PID control, IP control, other general control methods, modern control theory, or the like may be used. In particular, an offset such as an input voltage may be added in a subsequent stage, an upstream stage, or a parallel stage of the input current in order to increase speed and stability. Here, the input voltage detection signal 23 is added to the subsequent stage for each phase to obtain the input voltage command 26. In addition, this configuration example is a configuration in which control is performed individually for each phase, but using a known dq axis theory, it is configured with a control circuit that divides current and voltage of three phases into amplitude components and phase components. It may be.

  FIG. 7 shows a configuration example of the gate control circuit 27 in the converter control circuit 14. Each input voltage command 26 from the input current control circuit 20 and a signal from each carrier generation circuit 43 are input to the operational amplifiers 44a to 44c, respectively. The operational amplifier 44 a includes a subtractor 44 a 1 that obtains a difference between the input voltage command 26 and the signal from the carrier generation circuit 43 and an amplifier 44 a 2 that amplifies the difference. Similarly, the operational amplifier 44 b includes the input voltage command 26 and the carrier generation circuit 43. The operational amplifier 44c includes a subtractor 44c1 that obtains the difference between the input voltage command 26 and the carrier generation circuit 43, and an amplifier that amplifies the difference. 44c2. The outputs of the operational amplifiers 44a to 44c are input to the gate signal output circuits 45a to 45c. The outputs of the gate signal output circuits 45 a to 45 c become one input of the signal switching circuit 46. The other is turned off, and the power failure detection signal 29, which is the output of the power failure detection circuit 18, is used for this signal switching. The output of the signal switching circuit 45 is the gate signal 28. This configuration example is an example showing a generally-known triangular wave comparison method. The method for generating the gate pulse is not particularly limited.

FIG. 8 shows a configuration example of the input current control circuit 25 used in the present embodiment. When the converter phase order change signal 52 is on, the phase order (V phase and W phase) of the converter reference phase 22, the input voltage detection signal 23, and the input current detection signal 24 is changed. 3 is a configuration example of a gate control circuit 27 used in the embodiment. When the converter phase order switching signal 52 is on, the phase order (V phase and W phase) of the gate signal 28 is switched.

FIG. 10 is a diagram for explaining an operation example of the phase rotation abnormality detection circuit 51. (1) shows the waveform of the input voltage for one a phase (for example, U phase) of the AC input voltage. In the phase detection signal, the negative period of (1) is turned on. (3) shows an AC input voltage, another b phase (for example, V phase if the above phase is U phase), (4) is a b phase detection signal, and zero crossing that changes from negative to positive in (3). Turn on for about 1 ms from the point. (5) is a phase rotation detection signal when the phase rotation is normal, (6) is a phase b detection signal when the phase rotation is abnormal, and (7) is a phase rotation abnormality detection when the phase rotation is abnormal. Signal. (8) shows a state when the phase rotation in each phase is normal and a state when the phase rotation is abnormal.

  FIG. 11 is an example of the operation timing of the phase rotation abnormality detection circuit 51 used in this embodiment.

As shown in (1) of FIG. 11, when the AC power input of the power converter is switched from the commercial power supply 7 to the self-generated power supply facility 60 by the contactor 4 included in the switching circuit 3, the converter 10 detects a power failure once. At this time, the converter 10 stops, but after the power recovery, when the self-generated power supply facility 60 is connected in a phase sequence different state, first, the voltage sound signal 57 shown in (3) of FIG. Then, the D latch output 56 of the phase rotation abnormality detection circuit 51 becomes abnormal (on), and the converter phase order replacement signal 52 is turned on. Finally, when the power failure detection signal 29 is restored (sound), the converter 10 starts operating again. Therefore, the phase order can be changed before the operation of the converter 10 by detecting the phase rotation abnormality before the operation of the converter 10.

  When switching the AC power input of the power converter from the commercial power supply 7 to the generator 58, the converter 10 detects a power failure once. At this time, the converter stops, but when the generator 58 is connected in a state where the phase sequence is different after power recovery, first, the voltage sound signal 57 is restored (sound) as shown in (3) of FIG. After that, the D latch circuit output 56 of the phase abnormality detection circuit becomes abnormal (on), and the converter phase order switching signal 52 is turned on as shown in (4) of FIG. Finally, as shown in (5) of FIG. 11, when the power failure detection signal 29 is restored (healthy), the converter starts operating again. Therefore, by detecting the phase rotation abnormality before the converter operation, the phase order can be changed before the converter operation.

  In the embodiment described above, by detecting the phase rotation abnormality of the host system, the phase order of the input signals in the converter control circuit 14 constituting the power conversion device is changed, so that the converter control is performed soundly, and the converter By matching the control outputs in the order of the output phases, the converter control outputs can be output in a sound form even in a phase rotation abnormal state.

  The embodiment described above can be similarly implemented as follows.

  1) Not only the power converter provided with the converter and inverter described above, but also a power converter that converts AC power from a commercial power source and supplies it to a load, and a phase rotation detection circuit that detects the phase rotation of the commercial power source And a phase rotation change circuit that changes the phase rotation of the input and output of the power converter according to the output of the phase rotation detection circuit.

  2) Not only the above-described power converter including the converter and the inverter, but also a converter that converts AC power supplied from a commercial power source into DC power, and that the current of the converter matches a current amplitude reference. In a DC output type power conversion device having a current control means for creating an output voltage command and a gate control circuit for controlling a gate of a switching element constituting the converter based on a converter output command from the current control means, The power converter may include a phase rotation detection circuit that detects phase rotation of the commercial power supply, and a circuit that changes an input of the converter control circuit and a converter gate output based on the output of the phase rotation detection circuit.

  3) The rotation detection circuit described above includes a latch circuit that latches the output if there is an input voltage signal of the commercial power supply at the timing of the clock signal, and a logical product of the input voltage sound signal of the commercial power supply and the output of the latch circuit. When it is established, it outputs a phase order change signal, but the phase rotation detection circuit inputs the voltage signal of the commercial power supply, performs dq conversion, and detects an abnormality in the phase order by the secondary vibration generated on the d axis. You may do.

  DESCRIPTION OF SYMBOLS 1 ... Inverter, 2 ... Inverter transformer, 3 ... Switching circuit, 4 ... Contactor, 5 ... Semiconductor switch, 6 ... Load, 7 ... Commercial power supply, 8 ... AC filter, 9 ... Reactor for system connection, 10 ... Converter, DESCRIPTION OF SYMBOLS 11 ... DC capacitor, 12 ... Storage battery, 13 ... DC voltage detector, 14 ... Converter control circuit, 15 ... DC voltage control circuit, 16 ... DC voltage detection signal, 17 ... AC voltage detection circuit, 18 ... Power failure detection circuit, 19 ... PLL circuit, 20 ... input current control circuit, 21 ... input current amplitude reference, 22 ... converter reference phase, 23 ... input voltage detection signal, 24 ... input current detection signal, 25 ... AC current detection circuit, 26 ... input voltage command 27 ... Gate control circuit, 28 ... Gate signal of converter 10, 29 ... Power failure detection signal, 31 ... Switching element, 32 ... Diode, 33 ... Converter Output 34: Gate drive circuit 35: DC voltage reference signal 36 ... PI control circuit 41 ... Multiplier 42 ... P control circuit 43 ... Carrier generation circuit 44 ... Operational amplifier 45 ... Gate signal output circuit 46 ... Signal switching circuit, 51 ... Phase rotation abnormality detection circuit, 52 ... Converter phase order switching signal, 53 ... D latch circuit, 54 ... Clock input, 55 ... D latch input, 56 ... D latch output, 57 ... Input voltage sound signal , 58... AND circuit, 59.

Claims (5)

A power converter that converts AC power from a commercial power source and supplies it to a load;
A phase rotation detection circuit for detecting phase rotation of the commercial power supply;
A phase rotation change circuit that changes the phase rotation of the input and output of the power converter according to the output of the phase rotation detection circuit;
A power conversion device comprising: A converter that converts AC power supplied from commercial power into DC power;
An inverter that converts DC power converted by the converter into AC power and supplies the load to the load;
A storage battery connected to the input side of the inverter;
A switching circuit for switching power supply to the load to either the commercial power source side or the inverter side;
A current control circuit that creates an output voltage command for the converter so that the current of the converter matches a current amplitude reference;
In a power converter having a gate control circuit for controlling the gate of a switching element constituting the converter based on a converter output command from the current control circuit,
A phase rotation detection circuit for detecting phase rotation of the commercial power supply;
A power conversion device comprising: a circuit for changing an input of a converter control circuit and a converter gate output by an output of the phase rotation detection circuit. A converter that converts AC power supplied from commercial power into DC power;
A current control circuit that creates an output voltage command for the converter so that the current of the converter matches a current amplitude reference;
In a DC output type power converter having a gate control circuit for controlling a gate of a switching element constituting the converter, based on a converter output command from the current control circuit,
A phase rotation detection circuit for detecting phase rotation of the commercial power supply;
A power conversion device comprising: a circuit for changing an input of a converter control circuit and a converter gate output by an output of the phase rotation detection circuit.   The phase rotation detection circuit has a logical product of a latch circuit that latches the output if there is an input voltage signal of the commercial power supply at the timing of the clock signal, and an output voltage sound signal of the commercial power supply and the output of the latch circuit. The power converter according to any one of claims 1 to 3, wherein a phase order change signal is output at times.   The phase rotation detection circuit receives the voltage signal of the commercial power supply, performs dq conversion, and detects an abnormality in phase sequence by secondary vibration generated in the d-axis. The power converter according to claim 1.

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