JP5876748B2 - Converter device - Google Patents

Description

  The present invention relates to a converter device having improved control characteristics.

  A converter device that converts AC power into DC power is mainly composed of a semiconductor main circuit bridge and a controller that controls the output voltage to match the voltage command value. The controller uses the DC voltage feedback signal and the AC current feedback signal of the converter to perform processing such as comparison and amplification with the command value, and the output of the converter outputs a signal that follows the command value. In the converter device, for example, when the load inverter includes a smoothing capacitor, the load amount of the converter device also fluctuates due to the load amount of the load inverter, and the smoothing capacitor charge / discharge operation is performed. Fluctuates. The control constant of the controller is set so that the DC voltage is stabilized according to the capacity of the capacitor and the load amount. However, when the load fluctuates rapidly, output voltage hunting occurs by repeating overshoot and undershoot. If hunting occurs, the ripple current may increase the temperature of the capacitor and cause damage.

  In order to prevent the DC voltage hunting continuation as described above, a converter device has been proposed in which a control protection device including a hunting detector, a determiner, a controller gain corrector, and the like is added (see, for example, Patent Document 1). .)

Japanese Patent No. 3388277 (Overall)

  The method of Patent Document 1 compares the output DC voltage of the converter with a hunting vibration voltage determination value. If the DC voltage exceeds the vibration voltage determination value continuously for a set time or longer, it is determined that hunting has occurred, and the proportionality of the controller This is a technique that reduces the gain and suppresses the output DC voltage hunting of the converter.

  In such a conventional method, since the hunting is generated from the hunting of the output DC voltage of the converter until the proportional gain of the controller is reduced and the hunting of the output DC voltage of the converter is suppressed, the ripple current of the capacitor is reduced. This increases the stress and may shorten the life of the capacitor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a converter device that can suppress hunting before hunting occurs.

  In order to achieve the above object, a converter device of the present invention includes a main circuit bridge for supplying a DC voltage in parallel to a plurality of inverters each having a switch and a smoothing capacitor in a DC input section, and an output voltage of the main circuit bridge. A voltage detector for detecting an input current, a current detector, and a control unit for controlling an output voltage of the main circuit bridge, wherein the control unit detects a feedback voltage and a voltage reference detected by the voltage detector. A voltage controller that outputs a current reference so that this deviation is minimized, and amplifies the deviation between the feedback current detected by the current detector and the current reference so that this deviation is minimized. A current controller that outputs a voltage command for the main circuit bridge, a number detector that detects the number of operating inverters, and a load ratio based on the operating number information. And a gain generator for changing the optimum proportional gain of the voltage controller to a value obtained by calculation from the load amount ratio, and the calculation by the gain generator is based on the number of operating inverters. When the proportional gain when the inverter is zero is the no-load correction gain, and when the proportional gain when all the inverters are operating is the reference gain, the no-load correction gain is obtained by multiplying the reference gain by the load ratio. It is the operation which adds.

  According to the present invention, it is possible to provide a converter device that can suppress hunting before hunting occurs.

The circuit block diagram of the converter apparatus which concerns on Example 1 of this invention. The circuit block diagram of the converter apparatus which concerns on Example 2 of this invention. The circuit block diagram of the converter apparatus which concerns on Example 3 of this invention.

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

  FIG. 1 is a circuit configuration diagram of a converter device according to Embodiment 1 of the present invention. The converter device 2 includes a semiconductor main circuit bridge 2S that converts the three-phase AC power supplied from the commercial AC power source 1 into DC power, and the DC power output from the main circuit bridge 2S is unloaded by the smoothing capacitor 2P. Are then supplied in parallel to the load inverters 3A, 3B, 3C. Input switches 31A, 31B, 31C for operation selection are provided on the input side of the load inverters 3A, 3B, 3C, respectively, and the outputs of these input switches 31A, 31B, 31C are smoothing capacitors 32A, 32B, respectively. , 32C to the inverter bridges 33A, 33B, 33C, respectively. Although the AC outputs of the inverter bridges 33A, 33B, and 33C are connected to a load such as an electric motor, illustration of this portion is omitted.

  The internal configuration of the converter device 2 will be described below.

  In the main circuit bridge 2S, switching elements constituting the main circuit bridge 2S are controlled by a voltage command given from the controller 2C. A current detector 21 is provided on the input side of the main circuit bridge 2S, and a voltage detector 22 for detecting an output DC voltage is provided on the output side.

  The voltage reference set by the reference circuit 23 is given to the voltage controller 24 together with the feedback voltage detected by the voltage detector 22. The voltage controller 24 amplifies the deviation between the voltage reference and the feedback voltage, and outputs a current reference that minimizes this deviation. This current reference is supplied to the current controller 25 together with the feedback current detected by the current detector 21. The current controller 25 amplifies the deviation between the current reference and the feedback current, and outputs a voltage command that minimizes this deviation. In accordance with this voltage command, the main circuit bridge 2S outputs a DC voltage. Note that a gate circuit that generates a gate signal of a switching element constituting the main circuit bridge 2S by this voltage command is not shown.

  The voltage controller 24 is a so-called PI controller, and this proportional gain is supplied from the gain selector 27. The gain selector 27 is provided with information on the number of operating inverters 3 serving as a load of the converter device 2 from the number detector 26, and is set in advance so that the proportional gain to be selected is uniquely determined by the operating number information. A signal indicating whether or not the inverter 3A, 3B, or 3C is in operation is given to the number detector 26, and the number of detectors 26 can be used to grasp the number of operating units of the inverter 3.

  The converter device 2 supplies DC power to the inverter 3 having the smoothing capacitor 32, and controls the output DC voltage to be a voltage reference value with respect to the load fluctuation. When the load amount of the load inverter 3 changes, the DC voltage is increased or decreased by charging / discharging the capacitor 32. The proportional gain (amplification factor) of the voltage controller 24 is calculated based on the capacity of the capacitor 32 of the inverter 3 and is set so that the DC voltage control system is stabilized. For example, when the inverter 33A is disconnected, the capacitance of the capacitor 32 decreases. However, since the proportional gain set before the voltage controller 24 inverter 33A is disconnected is used, the amplification factor of the voltage controller 24 is the capacitance of the capacitor 32. , Hunting of overshoot and undershoot occurs, and the ripple current of the capacitor 32 increases. In order to prevent such an event, the number detector 26 acquires operation information of the inverters 3A, 3B, and 3C, which are loads of the converter device 2, and outputs the number information of the inverters. The gain selector 27 selects a proportional gain calculated according to the number of operating inverters 3 set in advance based on the operating number information given from the number detector 26 and outputs it as a proportional gain of the voltage controller 24. . The gain selector 27 selects the proportional gain so that it becomes a smaller proportional gain as described above when the number of operating inverters 3 decreases, and selects the proportional gain so as to become a larger proportional gain when it increases.

  With this configuration, the voltage controller 24 can use the optimum proportional gain corresponding to the number of operating inverters 3 serving as the load of the converter device 2 before the main circuit operation. The occurrence of hunting due to overshoot and undershoot of the generated DC voltage can be prevented.

  FIG. 2 is a circuit configuration diagram of the converter device according to the second embodiment of the present invention. The same parts of the second embodiment as those of the converter device according to the first embodiment of the present invention shown in FIG. The second embodiment differs from the first embodiment in that a load amount calculator 28 and a gain generator 29 are provided in place of the gain selector 27.

  The load amount calculator 28 in the controller 2C1 of the converter device 2 acquires the operating unit number information of the inverter 3 given from the number detector 26, calculates the load amount from the ratio between the unit number information and the total number of units, The quantity ratio is given to the gain generator 29. The gain generator 29 generates an optimal proportional gain of the voltage controller 24 from the load amount ratio. The optimum proportional gain is generated by calculating the load amount ratio by the reference gain and adding the no-load correction gain. Here, the no-load correction gain corresponds to the smoothing capacitor 2P connected to the output of the main circuit bridge 2S, and the reference gain corresponds to the case where all the inverters 3 are operated.

  For example, if the inverter capacity is generally the same, the smoothing capacitor capacity of the inverter is the same. Therefore, when the inverter 3 is composed of three inverters 3A, 3B, and 3C, the total number of loads is 3, and only one is operated. The load amount calculator 28 outputs a 1/3 load amount ratio, outputs 2/3 load amount ratio when operating two units, and 1 load amount ratio when all three units operate. Output. The gain generator 29 performs the above-described calculation to generate a proportional gain and inputs it to the voltage controller 24.

  With this configuration, as in the first embodiment, when the amount of the smoothing capacitor 32 included in the inverter 3 that is the load of the converter device 2 changes, before the main circuit of the converter device 2 is energized, the load The optimal proportional gain corresponding to the amount can be generated, the occurrence of hunting due to overshoot and undershoot of the DC voltage can be prevented, and the shortening of the life due to the ripple current of the capacitor 32 and the possibility of breakage can be prevented. .

  FIG. 3 is a circuit configuration diagram of the converter device according to the third embodiment of the present invention. The same parts of the third embodiment as those of the converter device according to the first embodiment of the present invention shown in FIG. The third embodiment is different from the first embodiment in that the number detector 26 is omitted, a driving operation panel 4 is provided instead, and a driving number signal is directly supplied from the driving operation panel 4 to the gain selector 27. It is.

  When an inverter to be operated is automatically selected from a plurality of inverters 3, an operation control panel 4 as shown in FIG. 3 is usually provided, and an inverter to be operated according to given conditions is selected. Give an operation command. Accordingly, the operation control panel 4 has a function of managing the operation of the entire system including the converter device 2, and the operation operation panel 4 provides information on how many inverters of the entire inverter 3 are operated. Have. For this reason, in such a case, it is not necessary to detect operation information from each inverter.

  Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, in the embodiment, the number of the inverters 3 has been described as three, but it is apparent that any number of two or more may be used.

  Further, it is obvious that the number detector 26 in the second embodiment may be omitted, and the driving operation panel 4 may be provided instead, and the driving number signal may be directly supplied from the driving operation panel 4 to the gain selector 27. is there.

  Further, the smoothing capacitor 2P can be omitted.

  In addition, when the capacity of each inverter 3 is different, instead of detecting the number of operating units, the load amount ratio is detected by detecting the input current of each inverter, and the total load ratio is obtained by adding these. Also good.

  Further, as a precaution, a means for detecting the ripple voltage of the voltage detector 22 may be provided, and protective means for reducing the proportional gain when the ripple voltage exceeds a predetermined value may be added.

DESCRIPTION OF SYMBOLS 1 Commercial alternating current power supply 2 Converter apparatus 3, 3A, 3B, 3C Inverter 4 Operation panel 2S Main circuit bridge 2P Smoothing capacitor 21 Current detector 22 Voltage detector 2C Controller 23 Reference circuit 24 Voltage controller 25 Current controller 26 Gain Selector 27 Number detector 28 Load amount calculator 29 Gain generator 31A, 31B, 31C Input switch 32, 32A, 32B, 32C Smoothing capacitor 33A, 33B, 33C Inverter bridge

Claims (2)

A main circuit bridge for supplying a DC voltage in parallel to a plurality of inverters each having a switch and a smoothing capacitor in a DC input unit;
A voltage detector for detecting an output voltage of the main circuit bridge and an input current, a current detector, and
A control unit for controlling the output voltage of the main circuit bridge,
The controller is
A voltage controller that amplifies a deviation between a feedback voltage detected by the voltage detector and a voltage reference, and outputs a current reference so that the deviation is minimized;
A current controller that amplifies a deviation between the feedback current detected by the current detector and the current reference, and outputs a voltage command of the main circuit bridge so that the deviation is minimized;
A number detector for detecting the number of operating inverters;
A load amount calculator for calculating the load amount ratio from this operating unit information;
A gain generator for changing the optimum proportional gain of the voltage controller from the load amount ratio to a value obtained by calculation;
With
The calculation by the gain generator is
When the proportional gain when the number of operating inverters is zero is the no-load correction gain, and the proportional gain when all the inverters are operating is the reference gain, a value obtained by multiplying the reference gain by the load ratio A converter device characterized in that the calculation is to add a no-load correction gain to . A main circuit bridge for supplying a DC voltage in parallel to a plurality of inverters each having a switch and a smoothing capacitor in a DC input unit;
A voltage detector for detecting an output voltage of the main circuit bridge and an input current, a current detector, and
A control unit for controlling the output voltage of the main circuit bridge,
The controller is
A voltage controller that amplifies a deviation between a feedback voltage detected by the voltage detector and a voltage reference, and outputs a current reference so that the deviation is minimized;
A current controller that amplifies a deviation between the feedback current detected by the current detector and the current reference, and outputs a voltage command of the main circuit bridge so that the deviation is minimized;
A load amount calculator for calculating a load amount ratio from information on the number of operating inverters given from an external operation control panel;
A gain generator for changing the optimum proportional gain of the voltage controller from the load amount ratio to a value obtained by calculation;
With
The calculation by the gain generator is
When the proportional gain when the number of operating inverters is zero is the no-load correction gain, and the proportional gain when all the inverters are operating is the reference gain, a value obtained by multiplying the reference gain by the load ratio A converter device characterized in that the calculation is to add a no-load correction gain to .

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