JP2000125570A - Power converter controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the switching loss of a switching element by reducing the number of switching times by integrating the absolute values of the error vectors between actual voltage value vectors and voltage command value vectors and, when the integrated value exceeds an allowable value, outputting a turning-on/off command to the switching element by selecting the optimum voltage vector. SOLUTION: Voltage commands Vd* and Vq* for a rotating system of coordinates outputted from a voltage command generating circuit 1 are converted into voltage command vectors Va* and Vb* on a rest frame by means of a rotation-rest converting circuit 2 and the errors between the vectors Va* and Vb* and currently outputted voltage command vectors Va and Vb are integrated by means of an integrator 3 and discriminated by means of an allowable value discriminating circuit 4. When the integrated voltage error value exceeds a set value, an output vector selecting circuit 5 switches the switching state of a switching element to the optimum switching state and, when the value does not exceed the set value, the circuit 5 maintains the element in the present condition. The turning-on/off of the switching element is controlled by using the outputs Vva* and Vvb* of the circuit 5 through a 2/3 coordinate transforming circuit 6 and a gate pattern deciding circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a power converter requiring low harmonic and sine wave outputs.

[0002]

2. Description of the Related Art When an electric motor or the like operated at a variable speed is operated by an inverter, the inverter must generate an AC voltage including a direct current. In addition, the inverter needs to generate an AC voltage to obtain a smooth rotation of the motor. The required voltage is required to be sinusoidal.

[0003] In inverter applications requiring such low harmonic sine wave output characteristics, NPC inverters (three-level inverters) are widely used in recent years.

FIG. 17 shows a main circuit configuration of an NPC inverter. Since the NPC inverter can output three stages of phase voltages and five stages of line voltage, harmonics can be greatly reduced, and the voltage applied to each device is, in principle, two. Since it has a feature that is reduced by a factor of one, it is easy to increase the capacity and the voltage.

[0005]

However, as shown in FIG. 17, the NPC inverter has a limitation in its constant voltage characteristics because the DC voltage is divided by a capacitor to increase the output level. That is, there is a period in which the neutral point of the DC power supply is connected to the load via the diode and the switching element, and during that period, current flows to the neutral point of the DC power supply.

For this reason, even though the DC voltage is constant,
The neutral point potential fluctuates at a frequency three times the output frequency. Also, if the DC component of the output voltage is biased, the divided potential is also biased greatly, and a large voltage may be applied to the device. This neutral point potential fluctuation can be suppressed by devising the output voltage of the inverter, but this requires setting the DC link voltage to be higher than the output line voltage required for the inverter load. There is.

In other words, the NPC inverter has a limit on the modulation rate. For example, assuming that the upper limit of the modulation factor is about 0.8, the peak value of the output line voltage of the power converter is (） 3/2) × M × Vdc (where M: modulation degree, Vdc: DC Voltage). That is, the upper limit of the peak value of the output line voltage is about 0.69 times the DC voltage.

In other words, in order to obtain the required peak value of the output line voltage, a DC voltage that is approximately 1.45 times the peak value is required. Therefore, in order to cope with a high DC voltage, it is necessary to connect a plurality of switching elements in series, and there is a problem that the number of used switching elements is directly reflected in the price, so that the power converter becomes expensive.

[0009] In general, triangular wave comparison PWM control with a constant carrier frequency is used for PWM control of an NPC inverter. This PWM control method not only has a low voltage utilization rate but also repeats switching in synchronization with a carrier cycle. Therefore, unnecessary switching operation is included, and as a result, switching loss increases.

[0010] The switching loss not only reduces the efficiency of the converter, but also causes problems such as an increase in the size of the stack and cooling system and an increase in the cost of the entire device. Accordingly, the present invention reduces the number of switching operations to a minimum and reduces switching loss, and furthermore, in a converter multiplexed in parallel using a voltage dividing transformer, a PWM for suppressing magnetic bias of the transformer is provided.
It is intended to provide a control method.

[0011]

In order to achieve the above object, a control device for a power converter according to a first aspect of the present invention provides a voltage command value vector based on a current command value and a load current detection value. Then, the starting point of the outputtable voltage vector which can be output by the power converter is set as the origin, and the voltage command value vector is set on a plane expressing each vector at the end point of the outputable voltage vector.

The absolute value of the error vector between the actually output voltage actual value vector and the voltage command value vector is integrated, and when the integrated value exceeds the allowable value, the actual output from the end of the error vector is performed. A possible output vector pointed to by the vector having the smallest angle with the error vector is selected as a voltage actual value vector to be actually output from among the difference vectors heading to the possible voltage vector, and based on the voltage actual value vector, a plurality of switching elements are selected. Is given.

According to a second aspect of the present invention, in the power conversion device multiplexed by the voltage dividing transformer, a voltage command value vector is set based on a current command value and a load current detection value. Then, the starting point of the outputtable voltage vector which can be output by the power converter is set as the origin, and the voltage command value vector is set on a plane expressing each vector at the end point of the outputable voltage vector.

Then, the absolute value of the error vector between the actually output voltage actual value vector and the voltage command value vector is integrated, and when the integrated value exceeds the allowable value, the actual output from the end of the error vector is performed. A possible output vector pointed to by the vector having the smallest angle with the error vector is selected as a voltage actual value vector to be actually output from among the difference vectors heading to the possible voltage vector, and based on the voltage actual value vector, a plurality of switching elements are selected. Is given.

According to a third aspect of the present invention, when the magnetic flux generated in the voltage dividing transformer reaches a predetermined value, the output of the power converting apparatus is reduced in a direction in which the magnetic flux of the voltage dividing transformer decreases. Sort out.

According to a fourth aspect of the present invention, there is provided a control device for a power conversion device, wherein an estimated magnetic flux of a voltage dividing transformer is obtained based on an exciting current of the voltage dividing transformer. The output of the power converter is distributed in the direction in which the magnetic flux of the voltage transformer decreases.

In the control device of the power converter according to claim 5 of the present invention, the estimated magnetic flux of the voltage dividing transformer is obtained based on the voltage applied to the winding of the voltage dividing transformer, and the estimated magnetic flux reaches a predetermined value. Then, the output of the power converter is distributed in a direction in which the magnetic flux of the voltage dividing transformer decreases.

In the control device for a power converter according to claim 6 of the present invention, an estimated magnetic flux of the voltage transformer is obtained based on an output switching function of the power converter, and when the estimated magnetic flux reaches a predetermined value, the divided voltage is calculated. The output of the power converter is distributed in a direction in which the magnetic flux of the transformer decreases.

According to a seventh aspect of the present invention, in the control device for a power converter, the estimated magnetic flux of the voltage dividing transformer obtained by the voltage dividing transformer magnetic flux estimating means is used as the magnetic flux of the voltage dividing transformer, the exciting current or the winding. The error with the actual magnetic flux is corrected based on the inter-voltage.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a first embodiment of the present invention. In FIG. 1, a voltage command of a rotating coordinate system that rotates in synchronization with a power supply output by a voltage command generating circuit 1 for controlling a current command and an actual current is Vd * and Vq *, and a rotation → stationary conversion circuit. In step 2, the voltage commands are converted into voltage commands Va * and Vb * on the stationary coordinates, and a voltage command vector is calculated.

The error between the obtained voltage commands Va *, Vb * and the actually output voltage command vectors Va, Vb is successively integrated by the integration controller 3 and the magnitude thereof is determined as a set allowable value. The circuit 4 determines the size.

If the voltage error integrated value exceeds the set value, the output vector selection circuit 5 switches to the optimum switching state and outputs the actual voltage vector. If not, keep the current state.

The output of the output vector selection circuit 5 is converted into a three-phase voltage command by a two-phase to three-phase conversion circuit 6, and the gate pattern determination circuit 7 turns on / off the self-extinguishing type element according to this value. Generates a gate pulse signal for controlling the gate pulse signal.

The operation of FIG. 1 will be further described with reference to FIGS. The voltage commands Vd * and Vq * are voltage commands on the rotating coordinates obtained from the voltage command generation circuit 1. The voltage commands Vd * and Vq * are converted into voltage command vectors Va * and Vb * in the rotation → stationary coordinate conversion circuit 2 according to the following equation. Here, the A-axis is in the U-phase direction, the B-axis is an axis advanced by 90 degrees from the A-axis, and θ is the phase of the voltage to be output by the inverter.

[0025]

Va * = Vd * × cos θ−Vq * × sin θ Vb * = Vd * × sin θ + Vq * × con θ As a result, voltage command vectors Va * and Vb * are obtained. In the integral controller 3, the voltage command vector Va *,
The deviation, that is, the error between Vb * and the currently output vectors Va and Vb is continuously integrated by the following equation.

[0026]

A0 = ∫ (Ea) dt Ea = Va * −Va B0 = ∫ (Eb) dt Eb = Vb * −Vb In the allowable value determination circuit 4, the magnitude of the voltage error integrated value Z obtained from the following equation And if this is greater than the set value,
The permissible value determination circuit 4 sends an optimum vector selection execution permission command to the vector selection circuit 5.

[0027]

[Mathematical formula-see original document] Next, a vector selection method in the vector selection circuit 5 will be described. FIG. 2 is a diagram showing a voltage vector that can be generated by one unit converter, FIG. 3 is a diagram showing how the optimum vector is selected, and FIG. 4 is a flowchart at that time.

As shown in FIG. 2, the vectors which can be output by one unit converter are seven vectors V0 to V7. When the optimum vector selection execution permission command is input from the permissible value determination circuit 4, the vector selection circuit 5 recognizes that the voltage error integrated value Z has exceeded the permissible value (STEP).
1) A small triangle to which the voltage command vector Vref (= Va * + jVb *) belongs is selected from among the small triangles surrounded by the seven output possible vectors (STEP 2).

Next, difference vectors Vs, Vt, connecting each vertex of the small triangle obtained earlier from the tip of the voltage command vector.
Vu is determined (STEP 3), the angle between the difference vector and the error vector Er is determined (STEP 4), and the vector of the vertex pointed by the vector that minimizes the angle between the error vector and the difference vector is the vector Va + jV to be output next.
b (STEP 5). The 2/3 coordinate conversion circuit 6 converts the output of the vector selection circuit 5 into three-phase voltage commands Vu, Vv, Vw using two-phase three-phase conversion represented by the following equation.

[0030]

(Equation 4) The gate pattern determination circuit 7 outputs the three-phase voltage commands Vu, V
Each self-extinguishing type element is turned on / off according to v and Vw.

As described above, the difference between the voltage command and the actually output voltage command vector is integrated, and switching is performed on condition that the value exceeds a predetermined value. As a result, when the difference is small, the time required for the integrated value to reach the permissible value becomes longer, and the switching frequency is reduced. Therefore, the switching operation can be suppressed to the minimum necessary in total, thereby reducing the switching loss. A highly efficient power converter can be realized.

Depending on the integrated value, a command may be output so that the pulse width is narrower than the minimum on-pulse width. In such a case, the pulse width is not output as instructed and the minimum pulse width is output. It is conceivable to output a pulse having a fixed pulse width. However, this results in equivalently distorting the voltage command, and as a result, the output voltage waveform is distorted.

Therefore, in such a case, the voltage vector is not switched even if the allowable value is exceeded, the integration is continued until the minimum on-pulse width is secured, and the voltage vector is switched when the minimum on-pulse width is secured. By
Since the minimum on-pulse width can be ensured and the time required to reach the next allowable value becomes longer by the amount exceeding the allowable value, the waveform is not distorted.

As described above, according to the present embodiment, the restriction on the minimum on-pulse width of the switching element can be avoided, and the voltage utilization rate can be increased to 1 at the maximum.
Next, a second embodiment of the present invention will be described.

FIG. 5 is a configuration diagram of a power converter according to a second embodiment of the present invention. In FIG. 5, a power converter includes a power converter 14 for converting an AC 13 into a DC, and inverter groups 15 and 1 connected in parallel to the power converter 14.
6, 17; a group of voltage dividing transformers 18, 19, and 20 for synthesizing output voltages of the same phase of the respective inverters; and a load 21 having an output of the voltage dividing transformer as an input of each phase.

The voltage dividing transformer group 18 comprises three voltage dividing transformers, and one terminal of a winding of each voltage dividing transformer is connected to a U-phase AC terminal of each of the inverters 15, 16 and 17. The other end of this winding is connected to the other phase winding, and the final end is
Connected to the phase. Similarly, the V-phase and W-phase of the inverter are connected to the voltage-dividing transformer groups 19 and 20, and the V-phase and the
Connected to W phase. The load 21 is described as a three-phase load for convenience of description, but is, for example, a variable speed motor load.

Here, the operation of the voltage dividing transformer is shown in FIG.
This will be described with reference to FIG. FIG. 6 is a diagram showing the magnetic flux generated by the voltage dividing transformer and the current of the winding at that time. Usually 3
Since the output currents of the two inverters operate in the same phase and have the same magnitude, the magnetic fluxes generated in the iron core cancel each other.

Therefore, at this time, the inductance of the voltage dividing transformer viewed from the inverter becomes zero, the voltage dividing transformer does not act as an inductance with respect to the load current, and the load current Iu flows through the winding of the voltage dividing transformer. Does not occur in principle.

On the other hand, the fundamental wave of the voltage generated by each inverter is the same, but the voltage waveform at the moment is different. Therefore, a current flowing between the inverters, for example, a cross current Iu23 is generated. FIG. 7 is a diagram showing the magnetic flux generated by the voltage dividing transformer and the current of the winding at this time.

Unlike FIG. 6, magnetic flux is generated in the voltage dividing transformer,
As a result, the inductance increases. Therefore, the cross current can be suppressed to a small value. In conventional multiplexing using an AC reactor, a voltage drop due to a load current occurs in the AC reactor, so that the inductance of the AC reactor cannot be designed to be too large. As a result, there is a disadvantage that the cross current flowing between the inverters becomes large.

On the other hand, in the multiplexing using the voltage dividing transformer, a voltage drop does not occur in principle with respect to the load current, and a large inductance necessary for suppressing the cross current is provided. Therefore, there is a feature that a power converter having a small cross current can be multiplexed.

When arbitrarily N inverters are multiplexed in parallel, the number of legs of the voltage dividing transformer may be N. Next, a control device according to a second embodiment will be described.

The control device according to the second embodiment has basically the same configuration as that of the first embodiment shown in FIG. 1, but since it is multiplexed, the output of the multiplex inverter The output vector selection circuit 5 supports multiplexing.

FIG. 8 shows a voltage vector that can be output by the three-multiplex inverter, and each vertex of the small triangle represents it. Compared with the single inverter, the output vector of the three-multiplex inverter increases in 37 ways.

Here, the operation of the output vector selection circuit 5 will be described. When the allowable value determination circuit 4 determines that the magnitude of the error integral value exceeds the allowable value, an output vector is selected according to the flowchart of FIG.

When the optimum vector selection execution permission command is input from the permissible value determination circuit 4, it is recognized that the voltage error integrated value Z has exceeded the permissible value (STEP 1), and the small value surrounded by 37 outputable vectors is recognized. Voltage command vector V from triangle
The small triangle to which ref belongs is selected (STEP 2).

Next, difference vectors Vs, Vt, which connect each vertex of the small triangle obtained earlier from the tip of the voltage command vector,
Vu is determined (STEP 3), the angle between the difference vector and the error vector Er is determined (STEP 4), and the vector of the vertex pointed by the vector that minimizes the angle between the error vector and the difference vector is determined as the next vector to be output. Select (STEP 5).

The 2/3 coordinate conversion circuit 6 converts the output of the vector selection circuit 5 into a three-phase voltage command V using two-phase to three-phase conversion.
u, Vv, Vw, and the gate pattern determination circuit 7
Then, the gate pattern of each phase is determined from the three-phase command voltage value.

According to the present embodiment, as in the first embodiment, the voltage utilization rate can be increased to a maximum of 1,
The switching operation can be suppressed to a necessary minimum, and a high efficiency power converter with reduced switching loss and reduced harmonics due to the multiplexing effect can be realized.

Next, a third embodiment of the present invention will be described. FIG. 9 is a configuration diagram of a control device according to the third embodiment of the present invention. Here, the difference from the control device of the second embodiment is that a magnetic flux detecting circuit 22 in the voltage dividing transformer and a magnetic flux saturation suppressing circuit 23 are added.

In FIG. 9, a magnetic flux detecting circuit 22 in the voltage dividing transformer is a circuit for detecting magnetic flux generated in each leg of the voltage dividing transformer, and a magnetic flux saturation suppressing circuit 23 is provided for each phase. By adjusting the output voltage allocated to each of the inverters 15, 16 and 17, the circuit suppresses the saturation of the magnetic flux in the voltage dividing transformer while making the line voltage as close as possible to the command value.

The operation of the magnetic flux saturation suppressing circuit 23 will be described with reference to the flowchart of FIG. Here, the output voltage of the inverter is represented by ± E as shown in FIG. First, the output voltage index V 'is initialized, and the current output voltage is converted into an integer to be the output voltage index V' (STEP 10). The branch is determined based on whether or not the output voltage index V 'matches the voltage command V * (STEP 11).

When the voltage command V * is larger than the output voltage index V ', the output of the inverter having an output of -E, which has the smallest magnetic flux compared to the other inverters, is set to + E output, and the output voltage index is set to + E. It is increased (STEP 12). On the other hand, when the voltage command V * is smaller than the output voltage index V ', the output of the inverter having the maximum magnetic flux as compared with the other inverters among the inverters having the output + E is set to the -E output, and the output voltage index is decreased. (STEP 13). This operation is repeated until the voltage index V 'matches the voltage command V * (STEP 14).

Next, the branch is determined based on whether or not the magnetic flux limitation index BI and the detected magnetic flux Bd match (STEP 1).
5). When the detected magnetic flux Bd exceeds the range of the magnetic flux limiting index BI, if there is an inverter having a minimum magnetic flux and a current output of -E, the inverter is switched to the + E output, and the inverter exceeding the limit value is output to the -E output. (STEP1
6). On the other hand, when the detected magnetic flux Bd falls below the range of the magnetic flux limiting index BI, if there is an inverter having a maximum magnetic flux and a current output of + E, the inverter is switched to a −E output,
The inverter below the limit value is set to + E output (STE
P17).

As described above, if the output of the inverter is distributed, the saturation of the magnetic flux can be suppressed while the influence on the output line voltage waveform is minimized. According to the present embodiment, the voltage utilization rate can be increased to a maximum of 1,
The switching operation can be suppressed to the minimum necessary, a high efficiency with reduced switching loss, a harmonic converter reduced by the effect of multiplexing, and a power converter that suppresses the demagnetization of the transformer magnetic flux can be realized.

Next, a fourth embodiment of the present invention will be described. FIG. 12 is a configuration diagram of a control device according to the fourth embodiment of the present invention. Here, the difference from the control device of the third embodiment shown in FIG. 9 is that an exciting current detection circuit 32 is provided instead of the magnetic flux detection circuit 22 in the voltage dividing transformer.

The exciting current detecting circuit 23 is a circuit for detecting an exciting current generated in a winding wound around each leg of the voltage dividing transformer. Normally, the magnetic flux is proportional to the exciting current, which is equivalent to obtaining the magnetic flux. For example, the first of a voltage dividing transformer
Assuming that the current input to the leg winding is It1 and the current output from the connection point is It0, the exciting current Im of this winding is obtained by the following equation.

[0058]

## EQU5 ## Im = It1-It0 / 3 This value is multiplied by a coefficient K obtained from the characteristics of the transformer core to obtain a magnetic flux Φ.

[0059]

Φ = K * Im By performing the magnetic flux saturation suppression 23 from this magnetic flux, the same effect as in the third embodiment can be obtained.

According to the present embodiment, the voltage utilization rate can be increased to a maximum of 1, the switching operation can be suppressed to the minimum required, the switching loss is reduced, and the switching efficiency is improved. It is possible to realize a power converter in which waves are reduced and the magnetic flux of the transformer is suppressed from being demagnetized.

Next, a fifth embodiment of the present invention will be described. FIG. 13 is a configuration diagram of a control device according to a fifth embodiment of the present invention. Here, the difference from the control device of the third embodiment shown in FIG. 9 is that a voltage dividing transformer winding voltage detecting circuit 33 is provided in place of the magnetic flux detecting circuit 22 in the voltage dividing transformer. It is.

The voltage dividing transformer winding voltage detecting circuit 33 detects the voltage applied between the voltage dividing transformer windings and estimates the magnetic flux in the voltage dividing transformer. Assuming that the voltage applied to the winding is e and the magnetic flux in the winding is Φ,

[0063]

## EQU7 ## It is obtained by Φ = ∫edt. Then, from this magnetic flux, the magnetic flux saturation suppression 23
By performing the above, the same effect as in the third embodiment can be obtained.

According to the present embodiment, the voltage utilization factor can be increased to a maximum of 1, the switching operation can be suppressed to the minimum necessary, the switching loss is reduced, the efficiency is higher, and the harmonics are increased by the effect of multiplexing. It is possible to realize a power converter in which waves are reduced and the magnetic flux of the transformer is suppressed from being demagnetized.

Next, a sixth embodiment of the present invention will be described. FIG. 14 is a configuration diagram of a control device according to the sixth embodiment of the present invention. Here, the difference from the control device of the third embodiment shown in FIG. 9 is that a DC voltage detecting circuit 34 and a voltage dividing transformer magnetic flux calculating circuit 35 are provided instead of the magnetic flux detecting circuit 22 in the voltage dividing transformer. It is a point that is.

The DC voltage detection circuit 34
The voltage dividing transformer magnetic flux calculating circuit 35 calculates the voltage applied to the voltage dividing transformer from the output switching function of the inverter, calculates the current comparison value, and calculates the current comparison value. This circuit calculates the magnetic flux generated in each leg of the voltage dividing transformer by integrating. The operation of the voltage dividing transformer magnetic flux calculation circuit 35 will be described by taking the U phase as an example. When the output of the DC voltage detection circuit 34 is E, the switching function of the inverter is

[0067]

[Expression 8] Su = 1 (Vu = + E), Su = 0 (Vu = −E) Sx = 0 (Vu = + E), and Sx = 1 (Vu = −E) Therefore, the U-phase AC voltage of the inverter 15 is

[0068]

EA1 = (Su−Sx) * E Similarly, EA is applied to the inverter 16.
2. EA3 is obtained for the inverter 17, and the coupling point phase voltage of the voltage dividing transformer is:

[0069]

EAAT = (EA1 + EA2 + EA3) / 3 From these, the voltage applied to the legs of the voltage dividing transformer by the inverter 15 is

[0070]

VLU1 = EA1-EAAT Therefore, the magnetic flux of the legs of this voltage dividing transformer is

[0071]

## EQU12 ## It can be obtained by Φ = ∫ (VLU1) dt. Then, from this magnetic flux, the magnetic flux saturation suppression 23
By performing the above, the same effect as in the third embodiment can be obtained.

According to the present embodiment, the voltage utilization factor can be increased to a maximum of 1, the switching operation can be suppressed to the necessary minimum, the switching loss is reduced, the efficiency is increased, and the harmonics are increased by the effect of multiplexing. It is possible to realize a power converter in which waves are reduced and the magnetic flux of the transformer is suppressed from being demagnetized.

Next, a seventh embodiment of the present invention will be described. FIG. 15 is a configuration diagram of a control device according to the seventh embodiment of the present invention. Here, the difference from the control device of the sixth embodiment shown in FIG. 14 is that a correction value calculation circuit 36 and an estimated magnetic flux correction circuit 37 are provided.

The estimated magnetic flux correction circuit 37 is a circuit for correcting an error between the estimated magnetic flux and the actual magnetic flux by adding the value obtained from the correction value calculation circuit 36 to the estimated magnetic flux of the voltage dividing transformer.

The correction value calculation circuit 36 uses any one of the exciting current, the magnetic flux of the voltage dividing transformer winding, and the voltage between the windings of the voltage dividing transformer for correction, and outputs the DC component Δ directly or through a low-pass filter. Assuming that the magnetic flux obtained from the voltage dividing transformer magnetic flux calculation circuit 35 is Φ and the gain is G, the corrected magnetic flux Φ
c is

[0076]

Φc = Φ + G * △ Then, by performing the magnetic flux saturation suppression 23 from this magnetic flux, the same effect as in the third embodiment can be obtained.

As described above, by correcting the magnetic flux obtained by the calculation using the actual current value or the like, the influence of the error in the magnetic flux calculation can be reduced. FIG. 16 is a schematic diagram of a variable-speed pumped-storage power generation system. The variable-speed pumped-storage power generation system includes a winding-type induction generator 39 having a primary winding connected to a system via a main transformer 38, and a first winding-supplying generator 39 for supplying an exciting current to a secondary winding of the winding-type induction generator. And second and third power converters 40, 41 and 42, and a voltage dividing transformer 43 for coupling the first, second and third power converters 40, 41 and 42.
u, 43v, 43w, a DC capacitor 44 provided on the DC side of the first, second, and third power converters, a DC power supply 45 for supplying power to the DC capacitor 44, and a wound induction generator 39 A first phase detector 46 for detecting a phase on the primary side, a second phase detector 47 for detecting a phase on the secondary side of the wound induction generator 39, and a wound induction generator 39.
Current detectors 48u, 48v, which detect the current on the secondary side of
48w, the difference between the output of the first phase detector 46 and the output of the second phase detector 47, and the current detectors 48u, 48v, 48
and a control circuit 49 for controlling the first, second, and third power converters based on the output of w.

By applying any of the second to sixth embodiments to the power converter constituting this variable speed pumped storage power generation system, a similar effect can be obtained in the present system. .

[0079]

According to the present invention, the voltage utilization of the inverter can be increased, the switching frequency can be suppressed low, and the large-capacity power conversion with less harmonics can be achieved due to the multiplexing effect of the voltage dividing transformer. The device can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a voltage vector that can be generated by one unit converter.

FIG. 3 is a diagram showing a voltage error integration vector and a difference vector.

FIG. 4 is a diagram illustrating selection of a voltage vector.

FIG. 5 is a configuration diagram of a control device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of an operation of the voltage dividing transformer.

FIG. 7 is an explanatory diagram of an operation of the voltage dividing transformer.

FIG. 8 is a diagram showing a voltage vector that can be generated by the three-to-three converter.

FIG. 9 is a configuration diagram of a control device according to a third embodiment of the present invention.

FIG. 10 is a view for explaining output distribution for suppressing magnetic bias.

FIG. 11 is a diagram for assuming the amplitude of an inverter.

FIG. 12 is a configuration diagram of a control device according to a fourth embodiment of the present invention.

FIG. 13 is a configuration diagram of a control device according to a fifth embodiment of the present invention.

FIG. 14 is a configuration diagram of a control device according to a sixth embodiment of the present invention.

FIG. 15 is a configuration diagram of a control device according to a seventh embodiment of the present invention.

FIG. 16 is a configuration diagram of variable speed pumped storage power generation.

FIG. 17 is a main circuit configuration diagram of an NPC inverter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Voltage command generation circuit 3 ... Integrator 4 ... Permissible value determination circuit 5 ... Output vector selection circuit 7 ... Gate pattern determination circuit 14 ... Power converter 15, 16, 17 ··· Inverters 18, 19 and 20 ··· Voltage dividing transformer 22 ··· Magnetic flux detecting circuit in voltage dividing transformer 23 ··· Flux saturation suppression circuit 32 ··· Voltage dividing transformer exciting current detecting circuit 33 ..Voltage detecting transformer winding voltage detecting circuit 35 ... Voltage calculating transformer magnetic flux calculating circuit 37 ... Estimated magnetic flux correcting circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Kitahata 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant (72) Inventor Takashi Fujita 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Corporation Inside the office (72) Inventor Takahisa Kageyama 1 Toshiba-cho, Fuchu-shi, Tokyo, Japan Inside the Toshiba Fuchu Plant, Inc. Masahiro 1F Toshiba-cho, Fuchu-shi, Tokyo F-term in the Fuchu factory of Toshiba Corporation (reference) 5H007 AA03 AA08 BB06 CA05 CB05 CC04 CC12 CC23 CC33 DA03 DA06 DC02 DC05 EA03

Claims (7)

[Claims] 1. A control device for a power converter that controls a power converter in which a plurality of switching elements are bridge-connected, a voltage command value to be output by the power converter based on a current command value and a load current detection value. Means for generating a vector, the starting point of an outputable voltage vector that can be output by the power conversion device is taken as the origin, and the voltage actually output on a plane expressing each vector at the end point of the outputable voltage vector. Integrate the absolute value of the error vector between the value vector and the voltage command value vector, and when the integrated value exceeds the allowable value, select the error vector from the difference vector from the end of the error vector to the voltage vector that can be actually output. The output possible vector pointed by the vector with the smallest angle between the power conversion device and the actual voltage vector actually output by the power conversion device Output vector selecting means for selecting,
A control device for a power conversion device, comprising: gate pattern determination means for calculating on / off commands for the plurality of switching elements based on the voltage actual value vector. 2. A plurality of power converters in which a plurality of switching elements are bridge-connected, and one end of a first winding wound around a plurality of legged iron cores is connected to an AC terminal of a first phase of the plurality of power converters. One end of a second winding wound around an iron core having a plurality of legs is connected to a first voltage dividing transformer having the other end of the winding coupled to a second phase AC terminal of the plurality of power converters. One end of a third winding wound around an iron core having a plurality of legs is connected to a second voltage dividing transformer having the other end of the winding coupled to a third phase AC terminal of the plurality of power converters. In a control device for a power conversion device configured to control a power conversion device including a third voltage-dividing transformer having the other end of the winding coupled thereto, the power conversion device may be configured based on a current command value and a load current detection value. Means for generating a voltage command value vector to be output; Taking the starting point of the output possible voltage vector as the origin, the absolute value of the error vector between the voltage actual value vector actually output and the voltage command value vector on the plane expressing each vector at the end point of the output possible voltage vector Integrate and, when the integrated value exceeds the permissible value, select the output possible vector indicated by the vector with the smallest angle with the error vector from among the difference vectors heading from the end of the error vector to the voltage vector that can be actually output. Output vector selecting means for selecting as a voltage actual value vector actually output by the power converter, and gate pattern determining means for calculating on / off commands for the plurality of switching elements based on the voltage actual value vector. A control device for a power conversion device, comprising: 3. The control device for a power conversion device according to claim 2, wherein a magnetic flux detecting means for detecting a magnetic flux generated in the voltage dividing transformer, an output of the output vector selecting means and an output of the magnetic flux detecting means. Magnetic flux saturation suppressing means for determining the output of the power conversion device in a direction in which the magnetic flux of the voltage dividing transformer decreases when the magnetic flux of the voltage dividing transformer reaches a predetermined value based on Control device for converter. 4. The control device for a power conversion device according to claim 2, wherein exciting current detecting means for detecting an exciting current of the voltage dividing transformer, and an estimated magnetic flux of the voltage dividing transformer based on the exciting current. When the magnetic flux of the voltage dividing transformer reaches a predetermined value based on the output of the voltage dividing transformer magnetic flux detecting and estimating means to be obtained and the output of the output vector selecting means and the output of the voltage dividing transformer magnetic flux detecting and estimating means, the voltage dividing transformer And a magnetic flux saturation suppressing means for determining an output of the power converter in a direction in which a magnetic flux of the converter decreases. 5. The control device for a power conversion device according to claim 2, wherein voltage detecting means for detecting a voltage applied to a winding of the voltage dividing transformer, and an estimated magnetic flux of the voltage dividing transformer based on the voltage. Transformer magnetic flux detection and estimating means for determining the output vector selecting means and the output of the voltage dividing transformer magnetic flux estimating means, and when the magnetic flux of the voltage dividing transformer reaches a predetermined value, the voltage dividing transformer And a magnetic flux saturation suppressing means for determining an output of the power converter in a direction in which a magnetic flux of the converter decreases. 6. The control device for a power conversion device according to claim 2, wherein the voltage-dividing transformer magnetic flux detection and estimation means for obtaining an estimated magnetic flux of the voltage-dividing transformer based on an output switching function of the power conversion device; Based on the output of the output vector selecting means and the output of the voltage dividing transformer magnetic flux estimating means, when the magnetic flux of the voltage dividing transformer reaches a predetermined value, the output of the power converter in the direction in which the magnetic flux of the voltage dividing transformer decreases. And a magnetic flux saturation suppressing means for determining the value. 7. The control device for a power converter according to claim 4, wherein the estimated magnetic flux of the voltage dividing transformer obtained by the voltage dividing transformer magnetic flux estimating means is divided. A control device for a power converter, comprising: means for correcting an error from an actual magnetic flux based on a magnetic flux of a transformer, an exciting current, or a voltage between windings.