JP2009303401A - Neutral point clamp power conversion device and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a neutral point clamp power conversion device, which simplifies a PWM operation, which charges a battery from a fuel cell, and which requires no additional snubber circuit. <P>SOLUTION: The neutral point clamp power conversion device, which includes DC power supplies having three-value potentials consisting of a DC generator and a battery and convert the three-value potentials into three-phase AC to drive an inductive load, includes an output voltage command calculation part (41), which determines a command value of an output voltage; a voltage vector calculation part (42), which calculates an output voltage vector based on the potential difference of the DC power supply having the three-value potentials; and an output time calculation part (43), which determines the output voltage vector and output time during a fixed period based on the vector component of the output voltage command and the output voltage vector. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a neutral point clamp power converter for converting power from a DC power source having three values combining a battery, a generator and the like to an arbitrary frequency.

The circuit configuration of a power conversion device that converts a DC power supply having a three-value potential to a three-phase AC is a neutral point clamp type power conversion device (for example, a neutral point fixed power conversion device in Patent Document 1 FIG. 1). Is common. As a power conversion device that converts a battery, a fuel cell, or the like into a three-phase alternating current using a direct current power source, there is a circuit configuration using a matrix converter (for example, Patent Document 2 FIG. 1 and Patent Document 3 FIG. 4).
The neutral point clamp type power converter connects two DC power supplies in series, selects and outputs the high-voltage potential and low-voltage potential of the power supply, and the intermediate potential that is the connection point with a switch element, and performs PWM modulation to convert to three-phase AC Power conversion is in progress. PWM is performed by changing the output vector in order to control the potential at the neutral point (see Patent Document 4).
In the power conversion device of Patent Document 2, a circuit configuration is provided in which a motor is driven using a high-pressure fuel cell and a low-voltage battery, regenerative power is charged to the battery, and the fuel cell can be charged from the fuel cell by a chopper circuit. It has become.
In the power conversion device of Patent Document 3, the fuel cell and the battery are switched to drive the motor, and the regenerative power of the motor is charged to the battery.
The matrix converter requires a protection circuit for the switch element and a complicated protection operation (FIG. 8 of Patent Document 5).
Japanese Patent Laying-Open No. 2003-88128 (page 8, FIG. 1) Japanese Patent Laying-Open No. 2006-60912 (page 15, FIG. 1) Japanese Patent Laying-Open No. 2006-129644 (page 12, FIG. 4) JP 2001-57784 A JP 2000-139076 (page 11, FIG. 8)

A conventional power converter using a matrix converter has a problem that a complicated switching sequence is required when switching current using a bidirectional switch. In addition, there has been a problem in that in order to switch the power from the DC power source, a complicated correction process such as correcting the voltage command according to each DC power source is required. Furthermore, since the matrix converter uses a bidirectional switch, the load current may be completely cut off. In order to protect the semiconductor elements used in the bidirectional switch, the load current is separately circulated. There is a problem that a snubber circuit for suppressing the surge voltage is necessary.
The present invention has been made in view of such problems, and is a small-sized device that uses a space vector to simplify PWM calculation, can charge a battery from a fuel cell, and does not require an additional snubber circuit. The object is to provide a low-cost neutral point clamp power converter and its control method.

In order to solve the above problem, the present invention is configured as follows.





According to the first aspect of the present invention, a DC power source having a ternary potential, and the DC power source is constituted by a DC generator and a battery, and the ternary potential is converted into a three-phase AC to drive an inductive load. In the sex point clamp power converter, an output voltage command calculation unit that determines a command value of an output voltage, a voltage vector calculation unit that calculates an output voltage vector based on a potential difference of a DC power supply having the three-value potential, And an output time calculation unit for determining an output voltage vector and an output time during a predetermined period based on the vector component of the output voltage command and the output voltage vector.
The invention according to claim 2 is the neutral point clamp power converter according to claim 1, wherein the inductive load is an electric motor.
According to a third aspect of the present invention, in the neutral point clamp power conversion device according to the second aspect, the voltage vector calculation unit applies a generator power to the inductance of the motor while the motor is stopped to generate a current. A voltage vector for charging is generated, and then an operation for generating a voltage vector for discharging the current charged in the inductance to the battery is repeated to charge the battery from the generator to the battery.
According to a fourth aspect of the present invention, there is provided the neutral point clamp power converter according to the second aspect, wherein the electric power of the generator is reduced during the output time of the zero output vector during the rotation of the electric motor. A voltage vector for charging current by applying to the inductance of the motor is generated, and then an operation for generating a voltage vector for discharging the current charged in the inductance to the battery is repeated to charge the battery from the generator. It is characterized by.

The invention according to claim 5 is the neutral point clamp power converter according to claim 1, wherein the inductive load is an AC system power supply.
According to a sixth aspect of the present invention, in the neutral point clamp power conversion device according to the fifth aspect, the output includes an inductive filter reactor, and the electric power of the generator is applied to the inductance of the inductive filter reactor to charge the current. And generating a voltage vector for discharging the current charged in the inductance to the battery, and charging the battery from the generator.
According to a seventh aspect of the present invention, in the neutral point clamp power converter according to the third aspect of the present invention, a product of a voltage vector and an output time for charging a current to the inductance, and a product of a voltage vector and a discharge time for discharging. The sum is zero.
The invention according to claim 8 is the neutral point clamp power converter according to claim 6, wherein a product of a voltage vector for charging current to the inductance and an output time, and a product of a voltage vector for discharging and a product of the output time. The sum is zero.
The invention according to claim 9 is a DC power source having a ternary potential, and the DC power source is composed of a DC generator and a battery, and converts the ternary potential into a three-phase AC to drive an inductive load. In the control method of the neutral point clamp power converter, the step of calculating the voltage command of the output three-phase voltage or vector, the step of calculating the component of the voltage command in the a and b vector directions and the region where the voltage command exists, A step of selecting a voltage vector to be applied based on a command to determine whether or not to charge an externally input battery and determining the number of times of switching; a step of calculating an output time of the voltage vector; and an output voltage And a step of driving the switch of the power conversion unit on and off based on the order of the vectors and the time.

According to the first and second aspects of the present invention, PWM is performed using the vector component of the voltage command, so that it is possible to provide a neutral point clamp power converter that simplifies the PWM generation circuit even when the fluctuation of the DC voltage is large. .
According to invention of Claim 3, the neutral point clamp power converter device which charges a battery from a generator can be provided.
According to the fourth aspect of the present invention, it is possible to provide a neutral point clamp power conversion device that charges a battery from a generator even during load operation.
According to invention of Claim 5, 6, the neutral point clamp power converter device which charges a battery from a generator in the state of grid connection can be provided.
According to the seventh and eighth aspects of the present invention, it is possible to provide a neutral point clamp power converter that generates a zero vector even when a battery is charged from a generator.
According to the ninth aspect of the present invention, since the PWM is performed using the vector component of the voltage command, there is provided a control method for the neutral point clamp power converter in which the PWM generation circuit is simplified even when the fluctuation of the DC voltage is large. can do.
According to the present invention, since there is no protection circuit or complicated protection operation, the apparatus can be reduced in size and cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a power converter according to the present invention. In the figure, 1 is a battery, 2 is a fuel cell, 3 is a neutral point clamp inverter main circuit, 4 is a control device, and 5 is a load. Reference numeral 41 denotes an output voltage command calculation unit, 42 denotes a voltage vector calculation unit, 43 denotes a voltage vector output time calculation unit, and 44 denotes a PWM output unit. In terms of circuit configuration, the relationship between the voltage V1 of the battery 1 and the voltage V2 of the fuel cell 2 must always be V1> V2. In the following embodiments, description will be made using the fuel cell 2 as a DC generator. However, the present invention is not limited to the fuel cell, and a DC output of a wind power generator or a solar power generator may be used. In the present invention, the configuration of the main circuit is not a matrix converter but a neutral point clamp inverter, and in the case of a small capacity, a freewheeling diode connected in parallel with the switch element of the neutral point clamp inverter is used. By doing so, a separate snubber circuit is not required. However, if the device becomes larger and the wiring length becomes longer as the output capacity of the power converter becomes larger, a separate snubber device is required. Since it can be applied to individual switch elements of the clamp inverter main circuit, the cost can be reduced as compared with a matrix converter that cannot be applied.

  FIG. 3 is an example showing 27 voltage vectors that can be output by the neutral clamp inverter of the present invention in a space vector diagram. Each vector is classified into 10 types of vectors of a, b, ap, an, bp, bn, cm, Op, Om, and On according to length and phase. Further, the correspondence between each vector and the inverter output voltage is shown in FIG. 3 as PNN in the order of U, V, and W phases. In the configuration of FIG. 1, the maximum value of the voltage that can be output by the inverter is the voltage V1 of the battery 1, the vectors that output this voltage are the a vector and the b vector, and the lengths of these vectors coincide with V1.

The lengths of the an and bn vectors are the voltage V2 of the fuel cell 2 from their switch state (MNN or the like). The lengths of the ap and bp vectors are the difference (V1−V2) between the voltage V1 of the battery 1 and the voltage V2 of the fuel cell 2 from the switch state (such as PMM). The cm vector is equal to the composition of the ap vector and the bn vector, and its length is formed by the points of PPP, PNN, and PMN. From the cosine theorem, considering the triangle, √ [V1 ^ 2 + (V1-V2) ^ 2-2 × V1 × (V1−V2) cos 60 °] = √ (V1 ＾ 2−V1 × V2 + V2 ＾ 2). The Op, Om, On vectors are called zero vectors, and their length is zero. The angle of the cm vector varies depending on the voltage V1 of the battery 1 and the voltage V2 of the fuel cell, and the angle θm formed from the adjacent a vector is expressed by | bn | / sinθm = | cm | / sin60 ° from the sine theorem (1) [Theta] m = asin [sin 60 [deg.] * V2 / [square root] (V1 ^ 2-V1 * V2 + V2 ^ 2)] (1)

The control circuit of FIG. 1 of the present invention generates a three-phase voltage command to be output by the inverter, and calculates the components of the voltage command in the a and b vector directions. When the voltage command is a vector indicated by a component (θ, k), the a vector component Va and the b vector component Vb are calculated as shown in FIG. When the angle between the voltage command vector and the adjacent a vector is θ ′, it is expressed by equation (2).
| Va | = k × 2 × sin (60 ° −θ ′) / √3
| Vb | = k × 2 × sin (θ ′) / √3 (2)
When the voltage command is a three-phase AC voltage, as shown in FIG. 5, the image is compared with a triangular wave (PWM carrier wave) having an amplitude 0.5 times the maximum value V1 of the inverter output voltage, and the maximum phase voltage The difference between the intermediate value and the intermediate value may be calculated as | Va |, and the difference between the intermediate value and the lowest value may be calculated as | Vb |. Further, the determination of where the command in this case exists in the region of FIG. 3 is determined by the correspondence between the magnitude of the voltage command and the phase. When the U-phase voltage command is Vu, the V-phase voltage command is Vv, and the W-phase voltage command is Vw,
A area: Vu>Vv> Vw
B region: Vv>Vu> Vw
C region: Vv>Vw> Vu
D region: Vw>Vv> Vu
E region: Vw>Vu> Vv
F region: Vu>Vw> Vv
It is.

The control circuit 4 performs PWM by selecting and time-division-outputting the voltage vector so that the a and b vector components of the voltage command coincide with the a and b vector components of the 27 voltage vectors.
In the simplest PWM modulation, PWM is performed using a and b vectors and a zero vector close to a voltage command vector. In this case, if the PWM cycle is Tc, the a vector output time is Ta and b vector output time is Tb, and the zero vector output time is To, then it is expressed as in equation (3).
Ta = Tc × | Va | / V1
Tb = Tc × | Vb | / V1 (3)
To = Tc-Ta-Tb
In the configuration of FIG. 1, when only the a vector and the b vector are used, power is supplied from the battery to the load. As the zero vector, any of Op, Om, and On may be used. However, if a zero vector that can be shifted from the a and b vectors to be output with the minimum number of switching times is used, the switching loss can be reduced.

When power is supplied from the fuel cell 2 to the load, PWM is performed using an and bn vectors and a zero vector close to the voltage command vector. In this case, when the PWM cycle is Tc, the output time of the an vector is Tan and the output time of the b vector is Tbn, and the output time of the zero vector is To,
Tan = Tc × | Va | / V2, Tbn = Tc × | Vb | / V2, To
= Tc-Tan-Tbn (4)
As above. In the power converter of the present invention, PWM can be easily performed by calculating the output time using the vector component of the voltage command and the vector close to the voltage command.

In order to charge the battery 1 from the fuel cell 2, first, assuming that the motor of the load is stopped, for example, an an (MNN) vector is output, and energy is applied from the fuel cell 2 to the motor inductance to generate a current. the charge, then, all of the switch elements turn off, the current charged in the inductance of the motor by rectifying operation of the circulating diode that is connected to the switch element and the antiparallel (energy = inductance * current ^2/2) Discharge and charge the battery. This operation is the same as that of the step-up chopper when V1> V2, and a current is supplied to the motor inductance (energy is applied to the motor inductance), and then an off operation is performed to charge the battery by rectification. As the vector for applying energy to the motor inductance, the energy from the fuel cell 2 to the motor moves by using the an or bn vector. The charging current can be controlled by adjusting the output time of the an (MNN) vector, which is also equivalent to the operation of the boost chopper.

Next, in the motor rotation state, for example, assuming that the voltage command vector is in the A region and power is being supplied from the fuel cell 2 to the load, the motor has an an (MNN), bn (MMN) vector and zero in the A region. PWM driving is performed by a vector. At this time, if the output time of an (MNN) is Tan, the output time of the bn (MMN) vector is Tbn, and the time of the zero vector is To, To is divided based on the values of V1 and V2, and Tan is (5 ) Tan '= Tan + To × V1 / (V1 + V2) (5)
Further, if the output time of the b (NPP) vector opposite to an (MNN) is Tbx, tbx is expressed by the following equation (6).
Tbx = To × V2 / (V1 + V2) (6)
The output time of the an (MNN) vector is increased without outputting the zero vector during the PWM period, and the b (NPP) vector is output. By this operation, a voltage of an output increase To × V1 / (V1 + V2) of the an (MNN) vector is applied to the motor, and energy is stored in the motor. The energy can be charged to the battery by outputting a b (NPP) vector. The average value of the voltage applied to the motor is the increment of the an (MNN) vector V2 × To × V1 / (V1 + V2), the reverse voltage of the b (NPP) vector −V1 × To × V2 / (V1 + V2). The sum is zero and the average voltage applied to the load motor does not change.
In this way, the battery can be charged from the fuel cell while the motor is normally driven. In this example, the an vector is increased and the reverse b vector is output. However, the bn vector may be increased to output the a vector opposite to the bn vector, and the an and bn vectors may be output. Both may be increased to output opposite a and b vectors.

When reducing the charging current, the time of the vector to be output is reduced as shown in Equations (7) and (8) by setting 0 <α <1, and the zero vector is output as the reduced time and the output time To ′ is set as ( 9) Correct as shown in the equation.
Tan ′ = Tan + α × To × V2 / (V1 + V2) (7)
Tbx = α × To × V1 / (V1 + V2) (8)
To ′ = (1−α) × To (9)
Thus, by controlling using α, the charging current can also be controlled.

  FIG. 2 is a schematic configuration diagram of the power conversion device according to the second embodiment of the present invention. In the figure, 1 is a battery, 2 is a fuel cell, 3 is a neutral clamp inverter main circuit, 4 is a control device, and 5 is a load. In terms of circuit configuration, the relationship between the voltage V1 of the fuel cell 2 and the voltage V2 of the battery 1 must always be V1> V2. The control circuit 4 performs PWM in the same manner as the power conversion device of the first embodiment, but the vector correspondence is different as follows.

When power is supplied from the fuel cell to the load, PWM is performed using the a and b vectors and the zero vector close to the voltage command vector. In this case, assuming that the PWM cycle is Tc, the output time of the a vector is Ta and the output time of the b vector is Tb, and the output time of the zero vector is To, Equation (10) is obtained.
Ta = Tc × | Va | / V1, Tb = Tc × | Vb | / V1, To = Tc−Ta−Tb
... (10)
As the zero vector, any of Op, Om, and On may be used. However, if a zero vector that can be shifted from the a and b vectors to be output with the minimum number of switching times is used, the switching loss can be reduced.

When power is supplied from the battery to the load, PWM is performed using the an and bn vectors close to the voltage command vector and the zero vector. In this case, when the PWM cycle is Tc, the output time of the an vector is Tan and the output time of the bn vector is Tbn, and the output time of the zero vector is To, the equation (11) is obtained.
Tan = Tc × | Va | / V2
Tbn = Tc × | Vb | / V2 (11)
To = Tc-Tan-Tbn
As above. In the power converter of the present invention, PWM can be easily performed by calculating the output time using the vector component of the voltage command and the vector close to the voltage command.

In order to charge the battery 1 from the fuel cell 2, first, assuming that the motor of the load is stopped, for example, an a (PNN) vector is output, energy is applied from the fuel cell 2 to the inductance of the motor, and then In addition, the bn (NMM) vector is output to charge the battery with the energy stored in the motor. This operation is the same as that of the step-down chopper when V1> V2, and a current is supplied to the motor inductance (energy is applied to the motor inductance), and then a current path to the battery is created to charge the battery. As the vector for applying energy to the motor inductance, the energy from the fuel cell 2 to the motor moves by using the a or b vector. The charge current can be controlled by adjusting the output time of the a (PNN) vector, which is also equivalent to the operation of the step-down chopper.
In this operation, since the bn (NMM) vector is output, when the charging current is small, the energy from the battery to the motor may return as the reflux current. To prevent this, for example, not the bn (NMM) vector, but all the U-phase switch elements are turned off, and the V-phase and W-phase are connected to M. Can block the current to.

Next, in the motor rotation state, for example, assuming that the voltage command vector is in the A region and power is being supplied from the fuel cell 2 to the load, the motor has the a (PNN) and b (PPN) vectors in the A region and zero. PWM driving is performed by a vector. At this time, the output time of a (PNN) is Ta, the output time of b (PPN) vector is Tb, and the time of zero vector is To. To is divided based on the values of V1 and V2, and Ta is corrected as shown in equation (12).
Ta ′ = Ta + To × V2 / (V1 + V2) (12)
Furthermore, when the output time of the bn (NMM) vector opposite to a (PNN) is Tbnx, the equation (13) is obtained.
Tbnx = To × V1 / (V1 + V2) (13)
The output time of the a vector is increased without outputting the zero vector during the PWM period, and the bn (NMM) vector is output. By this operation, a voltage of the output increase To × V2 / (V1 + V2) of the a (PNN) vector is applied to the motor, and energy is stored in the motor. By outputting a bn (NMM) vector of the energy, the battery can be charged.

  The average value of the voltage applied to the motor is the increment of the a (PNN) vector V1 × To × V2 / (V1 + V2), and the reverse voltage of the bn (NMM) vector −V2 × To × V1 / (V1 + V2). The sum is zero and the average voltage applied to the load motor does not change. In this way, the battery can be charged from the fuel cell while the motor is normally driven. In this example, the a vector is increased and the reverse bn vector is output. However, the b vector may be increased and an an vector opposite to the b vector may be output. Both may be increased and an an and bn vector in the opposite direction may be output.

When reducing the charging current, 0 <α <1 and the equations (14) and (15) are used.
Ta ′ = Ta + α × To × V2 / (V1 + V2) (14)
Tbnx = α × To × V1 / (V1 + V2) (15)
The time of the vector to be output is reduced, and the reduced time is corrected as shown in the equation (16) for the zero vector output time To ′.
To ′ = (1−α) × To (16)
Thus, by controlling using α, the charging current can also be controlled.

  FIG. 6 is a schematic configuration diagram of a power conversion device according to a third embodiment of the present invention. In the figure, 1 is a battery, 2 is a fuel cell, 3 is a neutral point clamp inverter main circuit, 4 is a control device, and 5 is a load. The control circuit 4 controls charging of the battery by selecting the ap, an, bp, and bn voltage vectors output from the motor drive and neutral point clamp inverter. FIG. 8 is a diagram illustrating a correspondence example between the load current direction and the charging current of the battery when the ap, an, bp, and bn vectors are output.

When power is supplied from the fuel cell to the load, PWM is performed using the an and bn vectors and the zero vector close to the voltage command vector. In this case, when the PWM cycle is Tc, the output time of the an vector is Tan and the output time of the bn vector is Tbn, and the output time of the zero vector is To, the equation (17) is obtained.
Tan = Tc × | Va | / V4
Tbn = Tc × | Vb | / V4 (17)
To = Tc-Tan-Tbn
It becomes. As the zero vector, any of Op, Om, and On may be used, but switching loss can be reduced by using a zero vector that can be shifted from the output an and bn vectors with the minimum number of switching times.

When power is supplied from the battery to the load, PWM is performed using ap and bp vectors and zero vectors that are close to the voltage command vector. In this case, when the PWM cycle is Tc, the ap vector output time is Tap, the bp vector output time is Tbp, and the zero vector output time is To, the equation (18) is obtained.
Tap = Tc × | Va | / V3
Tbp = Tc × | Vb | / V3 (18)
To = Tc-Tap-Tbp
As described above, in the power conversion device of the present invention, the output time is calculated using the vector component of the voltage command and the vector close to the voltage command, and the fuel cell drive and the battery drive are easily switched by selecting the vector. Can do.

  In order to charge the battery 1 from the fuel cell 2, first, assuming that the motor of the load is stopped, for example, an an (MNN) vector is output and the current of FIG. Next, energy is applied to the inductance, and a bp (MPP) vector is output, and the battery stores the energy stored in the motor as shown in FIG. 8 bp (MPP). This operation is the same operation as that of the flyback converter, in which a current is supplied to the motor inductance (energy is applied to the motor inductance), and then a current path to the battery is created to charge the battery. As the vector for applying energy to the motor inductance, the energy from the fuel cell 2 to the motor moves by using the an or bn vector.

  A vector is used when current flows from the fuel cell to the motor. However, when current flows from the motor to the battery, only the switch connected to the neutral point M is turned on, and the switch on the N side is turned off to rectify the freewheeling diode May create a current path to the battery. This operation has an advantage that generation of a circulating current from the battery to the motor can be suppressed when the charging current is small.

Next, in the motor rotation state, for example, assuming that the voltage command vector is in the A region and power is being supplied from the fuel cell 2 to the load, the motor has an an (MNN), bn (MMN) vector and zero in the A region. PWM driving is performed by a vector. At this time, the output time of an (MNN) is Tan, the output time of the bn (MMN) vector is Tbn, and the time of the zero vector is To. To is divided based on the values of V3 and V4, and Tan is corrected as shown in equation (19) Ta ′ = Ta + To × V3 / (V3 + V4) (19)
Furthermore, when the output time of the bp (MPP) vector opposite to an (MNN) is Tbpx, the equation (20) is obtained.
Tbpx = To × V4 / (V3 + V4) (20)
The output time of the an vector is increased without outputting the zero vector during the PWM period, and the bp (MPP) vector is output. By this operation, a voltage of an output increase To × V3 / (V3 + V4) of the an (MNN) vector is applied to the motor, and energy is stored in the motor. The energy can be charged into the battery by outputting a bp (MPP) vector.
The average value of the voltage applied to the motor is the increment of ap (MNN) vector V4 × To × V3 / (V3 + V4), and the reverse voltage by bp (MPP) vector −V3 × To × V4 / (V3 + V4). The sum is zero and the average voltage applied to the load motor does not change. In this way, the battery can be charged from the fuel cell while the motor is normally driven. In this example, the an vector is increased and a reverse bp vector is output. However, the bn vector may be increased to output an ap vector opposite to the bn vector, and the an and bn vectors. Both may be increased, and the ap and bp vectors in the reverse direction may be output.

When reducing the charging current, 0 <α <1 and the equation (21) is used.
Ta ′ = Ta + α × To × V2 / (V1 + V2)
Tbnx = α × To × V1 / (V1 + V2) (21)
The time of the vector to be output is reduced, and the time decrease is corrected as shown in the equation (22) for the zero vector output time To ′.
To ′ = (1−α) × To (22)
Thus, by controlling using α, the charging current can also be controlled.

  FIG. 7 is a schematic configuration diagram of a power conversion device according to a third embodiment of the present invention. In the figure, 1 is a battery, 2 is a fuel cell, 3 is a neutral clamp inverter main circuit, 4 is a control device, and 5 is a load. This is a circuit in which the positions of the fuel cell and the battery in FIG. 6 are reversed, and this circuit configuration can be derived in the same manner as the operation example of the third embodiment.

  In the above description, the motor is used as the load. However, as in the example of FIG. 9, the power converter may be provided with an inductive three-phase filter at the output and connected to the system. In this case, the battery is charged by temporarily storing energy in the inductance of the three-phase filter reactor and flowing the current to the battery, and the operation of the power converter is equivalent to motor driving. However, when connected to the system, a direct current component cannot be passed through the system, so that an operation equivalent to the motor stop state cannot be performed.

FIG. 10 shows an operation flow of the power converter of the present invention.
In step ST1, a three-phase voltage or vector voltage command to be output is calculated and generated. In step ST2, a component in the a and b vector directions of the voltage command and a region where the voltage command exists are calculated. Next, in step ST3, a voltage vector output from the power converter is selected based on an instruction whether or not to charge the battery input from the outside, and the output order is determined so that the number of times of switching is reduced as much as possible. Next, the output time of the voltage vector output in step ST4 is calculated. (If α is used, correction is also performed accordingly.) Next, the switch of the power converter is driven on and off based on the order and time of the voltage vectors output in step 5.

  Since this invention can charge a battery by selection of a vector, it can be applied also to the use of the grid connection apparatus which uses an electric vehicle, a direct current generator, and a battery together.

The block diagram of the power converter device which shows 1st Example of this invention The block diagram of the power converter device which shows 2nd Example of this invention Space vector diagram that the neutral point clamp inverter of the present invention can output Diagram showing the relationship between voltage command vector and output voltage vector The figure which shows the relationship between the voltage command of three phases, a carrier wave, and a vector component The block diagram of the power converter device which shows 3rd Example of this invention The block diagram of the power converter device which shows 4th Example of this invention The figure which shows the relationship between the output state of an ap, an, bp, bn vector, and the electric current of DC power supply Configuration diagram when the present invention is applied to grid interconnection Flow diagram showing processing steps of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Fuel cell 3 Neutral point clamp inverter main circuit 4 Control apparatus 41 Output voltage command calculating part 42 Voltage vector calculating part 43 Output time calculating part 44 PWM output part 5 Load (motor)
6 Three-phase filter reactor 7 AC system power supply

Claims (9)

A DC power source having a three-value potential, and the DC power source is composed of a DC generator and a battery;
In the neutral point clamp power converter for converting the ternary potential into a three-phase alternating current and driving an inductive load,
An output voltage command calculation unit for determining an output voltage command, a voltage vector calculation unit for calculating an output voltage vector based on a potential difference of the DC power supply having the three-value potential,
An output time calculation unit for determining an output voltage vector and an output time during a fixed period based on the vector component of the output voltage command and the output voltage vector;
A neutral point clamp power conversion device comprising:   The neutral point clamp power converter according to claim 1, wherein the inductive load is an electric motor.

The voltage vector calculation unit generates a voltage vector that charges the current by applying the power of the generator to the inductance of the motor while the motor is stopped, and then supplies the current charged in the inductance to the battery. 2. The neutral point clamp power converter according to claim 1, wherein a charge is charged from the generator to the battery by repeating the operation of generating a voltage vector to be discharged.

During the rotational drive of the electric motor, the output voltage vector is within the output time period of the zero vector,



A voltage vector for charging the current by applying the power of the generator to the inductance of the motor is generated, and then an operation for generating a voltage vector for discharging the current charged in the inductance to the battery is repeated. The neutral point clamp power converter according to claim 1, wherein the battery is charged with electric charge.   The neutral point clamp power converter according to claim 1, wherein the inductive load is a system AC power source.






A voltage vector having an inductive filter at an output, generating a voltage vector for charging current by applying generator power to the inductance of the inductive filter, and then discharging the current charged to the inductance to a battery The neutral point clamp power converter according to claim 5, wherein the electric charge is charged from the generator to the battery by repeating the operation of generating the generator.   4. The neutral point clamp power converter according to claim 3, wherein the sum of the product of the voltage vector for charging current to the inductance and the output time and the product of the voltage vector for discharging and the output time are zero.   7. The neutral point clamp power converter according to claim 6, wherein the sum of the product of the voltage vector for charging current to the inductance and the output time and the product of the voltage vector to be discharged and the output time are zero. A DC power source having a three-value potential, and the DC power source is composed of a DC generator and a battery;
In the control method of the neutral point clamp power converter for converting the ternary potential into a three-phase alternating current and driving an inductive load,
Calculating an output three-phase voltage or vector voltage command;
Calculating a component of the voltage command in the a and b vector directions and a region where the voltage command exists;
Selecting a voltage vector to be output based on a command whether or not to charge a battery input from the outside, and determining to reduce the number of times of switching;
Calculating the output time of the voltage vector;
A step of driving the switch of the power conversion unit on and off based on the order and time of the output voltage vector; and
The control method of the neutral point clamp power converter device characterized by providing.

Images