JP3813859B2 - Power converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-efficiency and economical power converter that combines a power diode rectifier and a voltage-type self-excited power converter.
[0002]
[Prior art]
In an electric railway DC feeding system, a system in which three-phase AC power is converted into DC power by a power diode rectifier connected in a three-phase bridge is often employed. This method has an advantage of being excellent in overload resistance and reducing the converter cost. However, there was a problem that when the train applied the regenerative brake, the power could not be regenerated to the AC power source side, and the regeneration was often invalidated. In addition, there is a load current dependency, and there is a drawback that the DC feeding voltage varies greatly depending on the load.
[0003]
FIG. 25 shows a circuit configuration of a conventional PWM converter (pulse width modulation control converter) capable of power regeneration. The PWM converter CNV has an AC terminal connected to terminals R, S, and T of a three-phase AC power supply SUP via an AC reactor Ls, a DC terminal is a DC smoothing capacitor Cd, and a three-phase output VVVF (variable voltage variable frequency). Connected to the DC terminal of the inverter INV. The AC terminal of the inverter INV is connected to the AC motor M. The PWM converter CNV includes six-arm six rectifier high-speed diodes D1 to D6 connected in a three-phase bridge, and self-extinguishing elements S1 to S6 which are switching elements for regenerative inverters connected in reverse parallel to the respective diodes. Yes. Diodes D1-D3 and self-extinguishing elements S1-S3 are arranged on the positive side, and diodes D4-D6 and self-extinguishing elements S4-S6 are arranged on the negative side. The inverter INV also has a circuit configuration similar to that of the converter CNV, but detailed description thereof is omitted here.
[0004]
The PWM converter CNV includes a control device including comparators C1 and C2, a voltage control compensator Gv (S), a multiplier ML, a current control compensator Gi (S), and a pulse width modulation control circuit PWMC. Although the comparator C1 and the voltage control compensator Gv (S) are common to each phase, the multiplier ML, the comparator C2, the current control compensator Gi (S), and the pulse width modulation control circuit PWMC are provided for each phase. It is done. Here, only the R-phase internal circuit configuration is shown in detail, but the S-phase and T-phase control circuits are similarly configured. Gate signals g1 and g4 for the R-phase self-extinguishing elements S1 and S4 are output from the R-phase control circuit, and gate signals g2 and g5 for the S-phase self-extinguishing elements S2 and S5 are output from the S-phase control circuit. , And gate signals g3 and g6 for the T-phase self-extinguishing elements S3 and S6 are output from the T-phase control circuit.
[0005]
The PWM converter CNV controls the input currents Ir, Is, It so that the DC voltage Vd applied to the DC smoothing capacitor Cd matches the voltage command value Vd * by the control device configured as described above. More specifically, the deviation between the voltage command value Vd * and the voltage detection value Vd is obtained by the comparator C1 and amplified by the voltage control compensator Gv (S) to obtain the amplitude command value Ism of the input current. Multiplier ML multiplies unit sine wave sinωt synchronized with the R-phase voltage and amplitude command value Ism of the input current, and sets the product as R-phase current command value Ir *. The R-phase current command value Ir * and the R-phase current detection value Ir are compared by the comparator C2, and the deviation is inverted and amplified by the current control compensator Gi (S). Here, normally, proportional amplification is used, and the gain is Gi (S) = − Ki. Ki is a proportionality constant. The voltage command value er * = − Ki × (Ir * −Ir), which is the output of the current control compensator Gi (S), is input to the PWM control circuit PWMC, and the R-phase self-extinguishing elements S1 and S4 of the converter CNV are input. Gate signals g1 and g4 are generated. The PWM control circuit PWMC compares the voltage command value er * with the carrier signal X (for example, a 1 kHz triangular wave). When er *> X, the element S1 is turned on (S4 is turned off), and er * <X. If so, the element S4 is turned on (S1 is turned off). As a result, the R-phase voltage Vr of the converter generates a voltage proportional to the voltage command value er *.
[0006]
When the R-phase input current Ir is Ir *> Ir, the voltage command value er * becomes a negative value, and Ir is increased. Conversely, when Ir * <Ir, the voltage command value er * becomes a positive value, and Ir is decreased. In this way, control is performed so that Ir * = Ir. S-phase and T-phase currents Is and It are similarly controlled.
[0007]
The voltage Vd applied to the DC smoothing capacitor Cd is controlled as follows. That is, when Vd *> Vd, the amplitude command value Ism of the input current increases. The current command value of each phase is in phase with the power supply voltage, and active power Ps proportional to the current Ism is supplied from the AC power supply SUP to the DC smoothing capacitor Cd. As a result, the voltage Vd rises and is controlled so that Vd * = Vd. Conversely, when Vd * <Vd, the amplitude command value Ism of the input current becomes a negative value, and the power Ps is regenerated to the AC power supply side. Therefore, the stored energy of the DC smoothing capacitor Cd is reduced, the voltage Vd is lowered, and the control is performed so that Vd * = Vd.
[0008]
The VVVF (variable voltage / variable frequency) inverter INV and the AC motor M are loads using the DC smoothing capacitor Cd as a voltage source, and during powering operation, the accumulated energy of the capacitor Cd is consumed and acts to reduce the voltage Vd. . Further, during the regenerative operation, the regenerative energy is returned to the smoothing capacitor Cd, so that the voltage Vd is increased. Since the DC voltage Vd is controlled to be constant by the PWM converter CNV as described above, the effective power corresponding to the regenerative energy is automatically supplied during the regenerative operation. Will be regenerated to the AC power supply side.
[0009]
Thus, according to the conventional PWM converter, the DC voltage Vd can be stabilized, power regeneration is possible, and the problem of regeneration invalidation in the DC power feeding system of the electric railway is solved.
[0010]
However, since the PWM converter performs switching at a high frequency, there is a drawback that the switching loss of the switching element becomes large. Further, the switching element needs to be capable of cutting the maximum value of the AC input current as a cutoff current. Therefore, it must be designed to withstand the breaking current even for a short overload (for example, 300% of the rated current), and a large power converter is required, resulting in an uneconomic system. was there.
[0011]
[Problems to be solved by the invention]
As described above, as a power converter capable of power regeneration, there is a self-excited converter (referred to as a PWM converter) based on pulse width modulation control. However, the cost is higher than that of a diode rectifier, and the overload capability is increased too much. There is a difficulty that can not be. In addition, there is a problem that switching loss accompanying PWM control becomes large and converter efficiency is poor.
[0012]
Therefore, an object of the present invention is to provide an economical power conversion device that is excellent in overload resistance, is capable of power regeneration, has high converter efficiency, and is economical.
[0013]
[Means for Solving the Problems]
The power converter of the invention according to claim 1 is a power diode rectifier having an AC terminal connected to an AC power source through an AC reactor, and a voltage in which the AC terminal is directly connected to the AC terminal of the power diode rectifier. A self-excited power converter, and a DC smoothing capacitor connected between the DC common terminals of the voltage self-excited power converter and the power diode rectifier via a recovery current suppression reactor and connecting the load device in parallel. It has.
[0014]
According to this configuration, during powering operation, the cut-off current of the voltage source self-excited power converter is kept small by controlling so that most of the current flows to the power diode rectifier. The voltage type self-excited power converter controls the input current by controlling the phase angle with respect to the power supply voltage with a constant pulse pattern (1 pulse, 3 pulses, 5 pulses, etc.) synchronized with the power supply voltage. Operates near input power factor = 1. Therefore, by switching the self-extinguishing element constituting the self-excited power converter near the zero point of the input current, it is possible to reduce the breaking current of the element.
[0015]
During regenerative operation, most of the current flows through the self-extinguishing element of the voltage type self-excited power converter. For example, it is economical to use the apparatus of the present invention to allow 300% overload during power running and 100% during regenerative operation. In electric railways, even if one train applies regenerative braking, the other trains are often in power running, and the above usage is appropriate. When operating at 100% regenerative power, the majority of the current flows through the self-extinguishing element. However, even during regenerative operation, the power source power factor is controlled to approximately 1, and switching of the self-extinguishing element is performed in the vicinity of the current zero point, so that the breaking current of the element can be kept small. Therefore, the switching loss is greatly reduced, and the self-excited power converter CNV can be configured with a self-extinguishing element having a small breaking current, thereby providing an economical device.
[0016]
Another feature of the present invention resides in that a recovery current suppressing reactor is arranged on the DC side. As a result, the AC terminal of the power diode and the AC terminal of the voltage type self-excited power converter can be directly connected, and when the self-extinguishing element is turned off, the current instantaneously moves to the power diode and self-extinguishes. Very little current flows through the high speed diode connected in antiparallel with the arc element. Therefore, since a current flows through the power diode having a small forward voltage drop, the loss is small and an efficient operation is possible.
[0017]
According to a second aspect of the present invention, in the power conversion device according to the first aspect, a recovery current suppression reactor is connected in parallel with a reset circuit that resets the recovery current flowing through the reactor.
[0018]
The recovery current suppressing reactor has a role of suppressing an excessive recovery current from flowing into each diode of the power diode rectifier when the self-extinguishing element of the voltage type self-excited power converter is turned on. Usually, the inductance of this reactor may be about several tens of μH, and may be about two orders of magnitude smaller than that of an AC reactor. When a recovery current flows through this reactor, it is necessary to reset the current once before the next switching. For this purpose, a recovery current reset circuit is connected in parallel to the reactor. For example, a reset circuit composed of a series circuit of a diode and a resistor is connected in parallel to the reactor. The time constant T of the reset circuit is given by T = L / R, where L is the inductance of the reactor and R is the resistance value of the resistor, and is preferably 1/3 or less of the switching period. When the self-excited converter is operated with one pulse, the power supply frequency fs is 50 Hz, and the switching cycle Tsw is Tsw = 1 / (6 · fs) = 1/300 [s] = 3.3 [ms]. Therefore, it is desirable to set Tp = 1 [ms] or less. If L = 50 μH and R = 0.1Ω, T = 0.5 [ms]. When the resistance R is increased, the voltage applied to the converter increases, and accordingly, the breakdown voltage of the element needs to be increased.
[0019]
In the conventional PWM converter, since the switching frequency is high and the switching of each self-extinguishing element connected in a three-phase bridge operates randomly, the reset time becomes very short. Therefore, it is not a good idea to insert recovery current suppressing reactors in a batch on the DC line of the PWM converter.
[0020]
As a circuit for resetting the recovery current flowing through the recovery current suppressing reactor, there is a series circuit of a diode and a resistor as described above, but a DC voltage source may be prepared instead of the resistor. The DC voltage source may be a battery or a large-capacity DC smoothing capacitor. Since energy is gradually stored in the DC voltage source, a circuit that consumes it or a circuit that regenerates power is often added.
[0021]
Thus, for example, by connecting a reset circuit including a diode and a resistor in parallel to the recovery current suppression reactor, the function of the recovery current suppression reactor inserted on the DC side can be maintained.
[0022]
According to a third aspect of the present invention, in the power conversion device according to the first or second aspect, the voltage-type self-excited power converter operates with a constant pulse pattern and adjusts the phase angle with respect to the voltage of the AC power supply. It is characterized by controlling the input current.
[0023]
The voltage type self-excited power converter performs switching in synchronization with the voltage of the AC power supply with a constant pulse pattern. If the DC voltage is constant, the voltage amplitude value is constant. In this state, by changing the phase angle φ of the output voltage with respect to the power supply voltage, the voltage applied to the AC reactor changes and the input current can be adjusted.
[0024]
By increasing the phase angle of the output voltage with respect to the power supply voltage in the delay direction, the effective power supplied from the AC power supply increases. Conversely, when the phase angle is increased in the advance direction, the active power is regenerated to the AC power source. Incidentally, there is no exchange of active power at the phase angle φ = 0. The phase angle of the input current is φ / 2 or π−φ / 2 with respect to the power supply voltage, and the input power factor is cos (φ / 2). Further, the phase difference between the input current and the AC output voltage of the self-excited converter is −φ / 2 or π + φ / 2, and the converter power factor is cos (φ / 2). The phase angle φ depends on the input current and the value of the AC reactor. The phase angle θ is at most about φ = 30 ° even during overload operation, and the power factor is cos 15 ° = 0.966.
[0025]
When the self-excited converter is controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current becomes small. However, since the converter power factor is close to 1 as described above, the current is near the zero point. Thus, switching is performed, and the cut-off current of the self-extinguishing element constituting the self-excited converter can be small. As a result, it is possible to provide a power conversion device that can regenerate power, has a high power factor, is highly efficient, and is low in cost.
[0026]
According to a fourth aspect of the present invention, in the power conversion device according to the first or second aspect, the voltage-type self-excited power converter operates in a one-pulse mode synchronized with the frequency of the AC power supply, and has a phase with respect to the voltage of the AC power supply. The input current is controlled by adjusting the angle.
[0027]
According to the invention described in claim 4, as in the invention according to claim 3, the self-excited converter is operated with a constant pulse pattern, but the number of pulses is one. Naturally, if the DC voltage is constant, the amplitude value of the AC side output voltage of the self-excited converter is constant. The input current is controlled by adjusting the phase angle φ of the AC-side output voltage of the self-excited converter with respect to the power supply voltage. When φ = 0, It is necessary to make the peak value and the peak value of the fundamental wave of the converter output voltage the same. Since the DC voltage is determined by the demand on the load side, a transformer is inserted on the power supply side so that the peak value of the fundamental component of the output voltage and the peak value of the power supply voltage are the same. Adjust the voltage.
[0028]
By operating the self-excited converter with one pulse, the number of switching is minimized and the converter efficiency is further improved. Moreover, the fundamental wave component of the AC side output voltage is increased, and the voltage utilization factor of the self-excited converter is improved. In addition, since the converter power factor is operated at approximately 1, switching is performed only once near the zero point of the input current, and the cutoff current of the self-extinguishing element is extremely high during power running and regenerative operation. Get smaller. As a result, a highly efficient and low-cost power conversion device can be provided. Further, not interrupting a large current means that it is close to soft switching, and an EMI noise is reduced and an environment-friendly power conversion device can be provided.
[0029]
According to a fifth aspect of the present invention, in the power conversion device according to any one of the first to fourth aspects, the voltage type self-excited power converter is adapted to change the voltage of the power supply when the voltage of the AC power supply fluctuates. In addition, the control operation is performed by changing the command value of the voltage applied to the DC smoothing capacitor.
[0030]
When the voltage type self-excited power converter is operated with one pulse or a constant pulse pattern, the amplitude value of the AC side output voltage of the power converter becomes constant, and when the power supply voltage becomes high, the converter becomes a delayed power factor operation, When the power supply voltage becomes low, the converter advances and becomes a power factor operation. Further, as the power factor decreases, the phase difference between the AC output voltage of the self-excited power converter and the input current increases, and the cutoff current of the self-extinguishing element constituting the self-excited power converter increases. Therefore, by adjusting the voltage Vd applied to the DC smoothing capacitor in accordance with the amplitude value of the power supply voltage Vs, control is always performed so that | Vs | = | Vc |. Thereby, it is possible to prevent an extreme decrease in the power source power factor or the converter power factor, and it is possible to prevent an increase in the cutoff current of the self-extinguishing element.
[0031]
According to a sixth aspect of the present invention, in the power conversion device according to any one of the first to fifth aspects, the voltage-type self-excited power converter has an angular frequency of ω, a power supply voltage of Vs, and an input current. Is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
It is characterized by controlling to become.
[0032]
The voltage Vd applied to the DC smoothing capacitor by the self-excited power converter is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
Thus, the phase of the input current can be matched with the phase of the power supply voltage, and the operation with the power source power factor = 1 can be performed. This effect is the same in regenerative operation. As a result, it is possible to provide a power conversion device that is excellent in overload resistance, low cost, and high power factor.
[0033]
According to a seventh aspect of the present invention, in the power conversion device according to any one of the first to fifth aspects, the voltage type self-excited power converter is configured such that the angular frequency of the AC power source is ω, the power source voltage is Vs, and the input current is Is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
It is characterized by controlling to become.
[0034]
The voltage Vd applied to the DC smoothing capacitor by the self-excited power converter is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
Thus, the phase angle of the input current with respect to the power supply voltage can be made to substantially match the phase angle of the AC side output voltage of the self-excited power converter. That is, the phase of the input current and the converter output voltage match, and the converter power factor = 1 can be operated. As a result, the cutoff current of the self-extinguishing element constituting the self-excited converter can be reduced, and the converter capacity can be reduced. This effect is the same in regenerative operation. Thereby, it is excellent in overload tolerance, can provide a low-cost and highly efficient power converter device.
[0035]
According to an eighth aspect of the present invention, there is provided a power conversion device including a three-phase transformer having a primary winding connected to a three-phase AC power source and having n sets of secondary windings having a predetermined phase difference. N power diode rectifiers in which an AC terminal is connected to each secondary winding of the phase transformer via an AC reactor, and an AC side terminal is directly connected to the AC terminals of these n power diode rectifiers. N voltage-type self-excited power converters, and n voltage-type self-excited power converters and n power diode rectifiers connected to a DC common terminal via a recovery current suppressing reactor, and a load device Are connected to each other in parallel.
[0036]
This device prepares a plurality of power converters that combine power diode rectifiers and voltage-type self-excited power converters, and includes a three-phase transformer having n sets of secondary windings having a predetermined phase difference. It is configured to be used for parallel multiple operation, and it is possible to increase the capacity of the conversion device and reduce the harmonic components of the input current supplied from the AC power supply. As a result, it is possible to provide a high-efficiency, low-cost, large-capacity power conversion device that is excellent in overload capability and capable of power regeneration.
[0037]
The invention according to claim 9 is the power converter according to claim 8, wherein the n voltage-type self-excited power converters operate with a constant pulse pattern and adjust the phase angle with respect to the voltage of the AC power supply. To control the voltage applied to the DC smoothing capacitor by controlling the AC input current.
[0038]
The voltage-type self-excited power converter operates with a constant pulse pattern and performs switching in synchronization with the voltage of the AC power supply. If the DC voltage is constant, the amplitude value of the AC output voltage of the self-excited converter becomes constant. In this state, by changing the phase angle φ of the output voltage with respect to the power supply voltage, the voltage applied to the AC reactor changes and the input current Is can be adjusted.
[0039]
By increasing the phase angle of the output voltage of each converter with respect to the power supply voltage in the delay direction, the effective power supplied from the AC power supply increases. Conversely, when the phase angle is increased in the advance direction, the active power is regenerated to the AC power source.
[0040]
When controlling a self-excited converter with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current is small. However, since the converter power factor is close to 1, switching is performed near the zero point of the current. However, the cut-off current of the self-extinguishing element constituting the self-excited converter may be small. Thereby, the harmonic component of input current is small, electric power regeneration is possible, a high power factor, high efficiency, and a low-cost power converter device can be provided.
[0041]
The invention according to claim 10 is the power converter according to claim 8, wherein the n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power supply, The AC input current is controlled by adjusting the phase angle to control the voltage applied to the DC smoothing capacitor.
[0042]
By operating each voltage type self-excited power converter in the 1-pulse mode, switching loss can be reduced and the voltage utilization factor of the self-excited converter can be improved. Further, since the self-excited converter is switched near the zero point of the input current, the cutoff current of the self-extinguishing element can be reduced. As a result, it is possible to provide a power conversion device that has excellent overload capability, low cost, high efficiency, and large capacity.
[0043]
A power conversion device according to an eleventh aspect of the present invention is a three-phase transformer having a primary winding connected to a three-phase AC power source and having n sets of secondary windings having a predetermined phase difference. N power diode rectifiers in which an AC terminal is connected to each secondary winding via an AC reactor, and n AC terminals directly connected to the AC terminals of these n power diode rectifiers Voltage-type self-excited power converters, and n DC-type smoothing capacitors connected to the DC common terminals of the n voltage-type self-excited converters and the power diode rectifier via a recovery current suppressing reactor, respectively. And n DC smoothing capacitors are connected in series, and load devices are connected to both ends connected in series.
[0044]
This device is provided with a plurality of power converters (n units) in which a power diode rectifier and a voltage-type self-excited power converter are combined, and has n sets of secondary windings having appropriate phase differences. A phase transformer is used to perform parallel multiplex operation on the AC side and to connect in series on the DC side. The converter has a large capacity, a high DC output voltage, and is supplied from an AC power source. Reduction of harmonic components of the input current can be achieved. As a result, it is possible to provide a high-efficiency, low-cost, large-capacity power conversion device that is excellent in overload capability and capable of power regeneration.
[0045]
The invention according to claim 12 is the power converter according to claim 11, wherein the n voltage-type self-excited power converters operate with a constant pulse pattern and adjust the phase angle with respect to the voltage of the AC power supply. To control the voltage applied to the DC smoothing capacitor by controlling the input current of each voltage source self-excited power converter.
[0046]
The voltage type self-excited power converter performs switching in synchronization with the voltage of the AC power supply with a constant pulse pattern. If the DC voltage is constant, the amplitude value of the AC output voltage of the self-excited converter becomes constant. In this state, by changing the phase angle of the output voltage with respect to the power supply voltage, the voltage applied to the AC reactor changes, and the input current of each voltage source self-excited power converter can be adjusted. When the self-excited converter is controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current becomes small. By operating the converter power factor close to 1, the zero point of the current Is Switching is performed in the vicinity, and the cut-off current of the self-extinguishing element constituting the self-excited converter CNV can be reduced.
[0047]
Increasing the phase angle φ of the output voltage of each converter with respect to the power supply voltage in the delay direction increases the effective power supplied from the AC power supply. Conversely, when the phase angle φ is increased in the advance direction, the active power is regenerated to the AC power source.
[0048]
The self-excited converter controls the voltage applied to each DC smoothing capacitor to be substantially constant. As a result, the sum voltage is controlled to be constant. As a result, the DC output voltage can be increased, the harmonic component of the input current is small, power regeneration is possible, and a high power factor, high efficiency, and low cost power conversion device can be provided. .
[0049]
The invention according to claim 13 is the power converter according to claim 11, wherein the n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power supply, The voltage applied to the DC smoothing capacitor is controlled by controlling the input current of each voltage source self-excited power converter by adjusting the phase angle.
[0050]
By operating each voltage type self-excited power converter in the 1-pulse mode, switching loss can be reduced and the voltage utilization factor of the self-excited converter can be improved. Further, since the self-excited converter is switched near the zero point of the input current, the cutoff current of the self-extinguishing element can be reduced. As a result, it is possible to provide a power conversion device that has excellent overload capability, low cost, high efficiency, and large capacity.
[0051]
The power converter of the invention according to claim 14 is configured such that a primary winding is connected in series for each phase with respect to a three-phase AC power supply, and an output voltage of the secondary winding has a predetermined phase difference. n three-phase transformers, n power diode rectifiers in a three-phase bridge connection in which an AC terminal is connected to each secondary winding of these n three-phase transformers, and these n power transformers N three-phase bridge-connected voltage-type self-excited power converters in which the AC terminal is directly connected to the AC terminal of the diode rectifier, and these n voltage-type self-excited power converters and n power diode rectifiers And a DC smoothing capacitor that is connected to each DC common common terminal via a recovery current suppressing reactor and connected in parallel with a load device.
[0052]
In this device, a plurality (n units) of power converters combining a power diode rectifier and a voltage-type self-excited power converter are prepared, primary windings are connected in series, and an appropriate phase difference is provided. It is configured to perform series multiplex operation using n three-phase transformers with secondary windings, which can increase the capacity of the converter and reduce the harmonic components of the input current supplied from the AC power supply. Can be planned. In particular, there is an advantage that the harmonic component of the AC side input current flowing through each converter can be reduced by the serial multiple operation, and the control pulses of the self-excited power converter can be reduced. Moreover, the conventional AC reactor can be omitted by using the leakage inductance of the three-phase transformer. As a result, it is possible to provide a high-efficiency, low-cost, large-capacity power conversion device that is excellent in overload capability and capable of power regeneration.
[0053]
The invention according to claim 15 is the power conversion device according to claim 14, wherein the n voltage-type self-excited power converters operate with a constant pulse pattern and adjust the phase angle with respect to the voltage of the AC power supply. To control the voltage applied to the DC smoothing capacitor by controlling the AC input current.
[0054]
The voltage type self-excited power converter performs switching in synchronization with the voltage of the AC power supply with a constant pulse pattern. If the DC voltage is constant, the amplitude value of the AC output voltage of the self-excited converter becomes constant. In this state, by changing the phase angle of the output voltage with respect to the power supply voltage, the voltage applied to the leakage inductance of the transformer changes, and the input current can be adjusted. When the self-excited converter is controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current is reduced. By operating the converter power factor close to 1, it is near the zero point of the current. Switching is performed in this manner, and the cut-off current of the self-extinguishing element constituting the self-excited converter can be reduced.
[0055]
By increasing the phase angle of the output voltage of each converter with respect to the power supply voltage in the delay direction, the effective power supplied from the AC power supply increases. Conversely, when the phase angle is increased in the advance direction, the active power is regenerated to the AC power source.
[0056]
The self-excited converter controls the input current so that the voltage applied to the DC smoothing capacitor is substantially constant. As a result, it is possible to provide a power converter that has a small harmonic component of the input current, can regenerate power, and has a high power factor, high efficiency, and low cost.
[0057]
The invention according to claim 16 is the power converter according to claim 14, wherein the n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power supply, The AC input current is controlled by adjusting the phase angle to control the voltage applied to the DC smoothing capacitor.
[0058]
According to this invention, as in the invention according to claim 15, the self-excited converter is operated with a constant pulse pattern, but the number of pulses is one. Naturally, if the DC voltage is constant, the amplitude value of the AC side output voltage of the self-excited converter is constant. The input current is controlled by adjusting the phase angle φ of the sum voltage of the AC side output voltage of the self-excited converter with respect to the power supply voltage. When φ = 0, the input current = 0 It is necessary that the peak value of the power supply voltage and the fundamental peak value of the sum voltage of the converter output voltage be the same. Since the DC voltage is determined by the load-side requirements, the values are adjusted so that the secondary side voltage of the three-phase transformer is the same as the fundamental wave component of the AC side output voltage of each self-excited converter.
[0059]
By operating the self-excited converter with one pulse, the number of switching is minimized and the converter efficiency is further improved. Moreover, the fundamental wave component of the AC side output voltage is increased, and the voltage utilization factor of the self-excited converter is improved. In addition, since the converter power factor is operated at approximately 1, switching is performed only once near the zero point of the input current Is, and the cutoff current of the self-extinguishing element during power running operation and regenerative operation is Extremely small. As a result, a highly efficient and low-cost power conversion device can be provided. In addition, the fact that a large current is not cut off is close to soft switching, EMI noise is reduced, and an environment-friendly power conversion device can be provided.
[0060]
According to a seventeenth aspect of the present invention, in the power conversion device according to any one of the eighth to sixteenth aspects, a reset circuit for resetting a current flowing through each of the reactors is connected in parallel to each of the recovery current suppressing reactors. It is characterized by that.
[0061]
The recovery current suppressing reactor has a role of suppressing an excessive recovery current from flowing into each diode of the power diode rectifier when the self-extinguishing element of the voltage type self-excited power converter is turned on. Usually, the inductance of this reactor may be about several tens of μH, and may be about two orders of magnitude smaller than that of an AC reactor. When a recovery current flows through this reactor, it is necessary to reset the current once before the next switching. For this purpose, a recovery current reset circuit is connected in parallel to the reactor. For example, a reset circuit composed of a series circuit of a diode and a resistor is connected in parallel to the reactor. The time constant T of the reset circuit is given by T = L / R, where L is the inductance of the reactor and R is the resistance value of the resistor, and is preferably 1/3 or less of the switching period. When the self-excited converter is operated with one pulse, the power supply frequency fs is 50 Hz, and the switching cycle Tsw is Tsw = 1 / (6 · fs) = 1/300 [s] = 3.3 [ms]. Therefore, it is desirable to set Tp = 1 [ms] or less. If L = 50 μH and R = 0.1Ω, T = 0.5 [ms]. When the resistance R is increased, the voltage applied to the converter increases, and accordingly, the breakdown voltage of the element needs to be increased.
[0062]
As a circuit for resetting the recovery current flowing through the recovery current suppressing reactor, there is a series circuit of a diode and a resistor as described above, but a DC voltage source may be prepared instead of the resistor. The DC voltage source may be a battery or a large-capacity DC smoothing capacitor. Since energy is gradually stored in the DC voltage source, a circuit that consumes it or a circuit that regenerates power is often added.
[0063]
Thus, for example, by connecting a reset circuit including a diode and a resistor in parallel to the recovery current suppression reactor, the function of the recovery current suppression reactor inserted on the DC side can be maintained.
[0064]
According to an eighteenth aspect of the present invention, in the power conversion device according to any one of the eighth to seventeenth aspects, the n voltage-type self-excited power converters have a power supply voltage when the voltage of the AC power supply fluctuates. The control is performed by changing the command value of the voltage applied to the DC smoothing capacitor in accordance with the change of.
[0065]
When n voltage-type self-excited power converters are operated with one pulse or a constant pulse pattern, the amplitude value of the AC output voltage of the power converter becomes constant, and when the power supply voltage becomes high, the converter When the operation is started and the power supply voltage is lowered, the converter is advanced in a power factor operation. Further, as the power factor decreases, the phase difference between the AC output voltage of the self-excited power converter and the input current increases, and the cutoff current of the self-extinguishing element constituting the self-excited power converter increases. Therefore, by adjusting the voltage Vd applied to the DC smoothing capacitor in accordance with the amplitude value of the power supply voltage Vs, control is always performed so that | Vs | = | Vc |. Thereby, it is possible to prevent an extreme decrease in the power source power factor or the converter power factor, and it is possible to prevent an increase in the cutoff current of the self-extinguishing element.
[0066]
According to a nineteenth aspect of the present invention, in the power conversion device according to any one of the eighth to eighteenth aspects, the n voltage-type self-excited power converters have an angular frequency of the AC power supply of ω and a power supply voltage of Vs. When the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
It is characterized by controlling to become.
[0067]
The voltage Vd applied to the DC smoothing capacitor by n self-excited power converters is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
Thus, the phase of the input current can be matched with the phase of the power supply voltage, and the operation with the power source power factor = 1 can be performed. This effect is the same in regenerative operation. As a result, it is possible to provide a power conversion device that is excellent in overload resistance, low cost, and high power factor.
[0068]
The invention according to claim 20 is the power converter according to any one of claims 8 to 18, wherein the n voltage-type self-excited power converters have an angular frequency of the AC power supply of ω and a power supply voltage of Vs. When the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
It is characterized by controlling to become.
[0069]
The voltage Vd applied to the DC smoothing capacitor by n self-excited power converters is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
The phase angle of the input current with respect to the power supply voltage can be made to substantially coincide with the phase angle of the AC output voltage of the self-excited power converter. That is, the phase of the input current and the converter output voltage match, and the converter power factor = 1 can be operated. As a result, the cutoff current of the self-extinguishing element constituting the self-excited converter can be reduced, and the converter capacity can be reduced. This effect is the same in regenerative operation. Thereby, it is excellent in overload tolerance, can provide a low-cost and highly efficient power converter device.
[0070]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
FIG. 1 is a block diagram showing an embodiment of the power conversion apparatus of the present invention. Here, circuit elements having the same or similar functions as those in FIG. 25 are denoted by the same reference numerals, and detailed description thereof is omitted. In the main circuit of FIG. 1, a power diode rectifier REC is additionally disposed between the AC reactor Ls and the voltage source self-excited converter CNV in the main circuit of FIG. The rectifier REC is composed of power diodes PD1 to PD6 having a three-phase bridge connection, and the AC terminal is connected to the power receiving terminals R, S, and T of the three-phase AC power supply SUP through the AC reactor Ls, and the voltage source itself. It is directly connected to the AC terminal of the excitation converter CNV. The DC terminal of the rectifier REC and the DC terminal of the self-excited converter CNV are connected to both ends of the DC smoothing capacitor Cd via a recovery current suppressing reactor Lp. A load device LOAD composed of a VVVF inverter INV and an AC motor M is connected to both ends of the DC smoothing capacitor Cd using this as a voltage source.
[0071]
The recovery current suppression reactor Lp has a role of suppressing excessive recovery current from flowing into each diode of the rectifier REC when the self-extinguishing element of the power converter CNV is turned on. It is designed to have an inductance value, and may be about two orders of magnitude smaller than the AC reactor Ls. The recovery current suppressing reactor Lp is connected in parallel with a reset circuit composed of a series circuit of a diode Dp and a resistor Rp in the forward direction with respect to the direct current during powering. This reset circuit has a role of resetting the recovery current flowing in the reactor Lp.
[0072]
FIG. 1 also shows a control device for sending gate signals g1 to g6 to the self-extinguishing elements S1 to S6 for controlling the voltage source self-excited converter CNV. The control device includes comparators C1 and C3, an adder C2, a voltage control compensation circuit Gv (S), a current control compensation circuit Gi (S), a feedforward compensator FF, a coordinate conversion circuit A, and a power supply synchronization phase detection circuit PLL. And a phase control circuit PHC. The voltage Vd applied to the DC smoothing capacitor Cd is detected, and is compared with the voltage command value Vd * by the comparator C1. The deviation εv (= Vd * −Vd) is integrated or proportionally amplified by the voltage control compensation circuit Gv (S), and the output value is input to the first input terminal of the adder C2. On the other hand, the DC current Idc consumed by the load LOAD is detected and input to the second input terminal of the adder C2 via the feedforward compensator FF. The output Iq * of the adder C2 becomes the command value of the effective current supplied from the power supply SUP. The coordinate converter A converts the detected values of the three-phase input currents Ir, Is, It supplied from the power supply SUP to the power converter into a dq axis (DC amount). The q-axis current Iq obtained by the coordinate conversion represents an effective current detection value, and the d-axis current Id represents a reactive current detection value.
[0073]
The comparator C3 compares the effective current command value Iq * with the detected effective current value Iq, amplifies the deviation εi (= Iq * −Iq) by the current control compensation circuit Gi (S), and the phase angle command value φ * The power supply synchronization phase detection circuit PLL generates phase signals θr, θs, θt synchronized with the three-phase AC power supply voltage and inputs the phase signals to the phase control circuit PHC. The phase control circuit PHC generates the gate signals g1 to g6 of the self-extinguishing elements S1 to S6 of the power converter CNV using the phase angle command value φ * and the phase signals θr, θs, θt for each phase. The voltage type self-excited power converter CNV controls the phase angle φ with respect to the power supply voltage by a constant pulse pattern (1 pulse, 3 pulses, 5 pulses, etc.) synchronized with the power supply voltage by the gate signals g1 to g6. Control input current.
[0074]
FIG. 2 is a voltage / current vector diagram for explaining the control operation of the apparatus of FIG. In the figure, Vs is the power supply voltage, Vc is the AC output voltage of the self-excited power converter CNV, Is is the input current, jωLs · Is is the voltage drop due to the AC reactor Ls (however, the resistance of the reactor Ls is sufficiently small) Ignore). As a vector, there is a relationship of Vs = Vc + jωLs · Is.
[0075]
The peak value of the power supply voltage Vs is matched with the fundamental peak value of the AC output voltage Vc of the self-excited power converter CNV. The DC voltage Vd is often determined by a request from the load side, and when the pulse pattern is determined, the fundamental wave peak value of the AC output voltage Vc is determined. Therefore, a transformer is installed on the power supply side, and the peak value is adjusted with the secondary voltage as Vs.
[0076]
The input current Is can be controlled by adjusting the phase angle φ of the AC output voltage Vc of the power converter CNV with respect to the power supply voltage Vs. That is, when the phase angle φ = 0, the voltage jωLs · Is applied to the AC reactor Ls is zero, and the input current Is is also zero. As the phase angle (delay) φ is increased, the voltages of jωL and • Is increase, and the input current Is also increases in proportion to the value. The input current vector Is is 90 ° behind the voltage jωLs · Is, and is a vector delayed by φ / 2 with respect to the power supply voltage Vs. Therefore, the input power factor viewed from the power source side is cos (φ / 2).
[0077]
On the other hand, when the AC output voltage of the power converter CNV is increased in the advance direction by the phase angle φ as shown by Vc ′ in FIG. 2, the voltage jωLs · Is applied to the AC reactor Ls becomes negative, and the input current is Is. As indicated by ', the phase angle is (π−φ / 2) with respect to the power supply voltage Vs. That is, the electric power Ps = Vs · Is becomes negative, and the electric power can be regenerated to the power source. When the AC output voltage Vc is shifted in the direction of Vc ′ along the broken line in the figure with respect to the power supply voltage Vs, the input current vector Is changes in the direction of Is ′ along the broken line.
[0078]
In FIG. 1, the effective current Iq is controlled as follows.
[0079]
When Iq *> Iq, the output φ * of the current control compensation circuit Gi (S) increases to increase the input current Is. Since the input power factor is approximately 1, the effective current Iq increases and eventually settles as Iq * = Iq. On the contrary, when Iq * <Iq, the output φ * of the current control compensation circuit Gi (S) decreases or becomes a negative value, and the input current Is is decreased. Since the input power factor≈1, the effective current Iq decreases, and Iq * = Iq is also settled.
[0080]
Further, the voltage Vd of the DC smoothing capacitor Cd is controlled as follows.
[0081]
When Vd *> Vd, the output Iq * of the adder C2 on the output side of the voltage control compensation circuit Gv (S) increases and is controlled to Iq * = Iq as described above, so that the active power Ps is It is supplied from the AC power supply SUP to the DC smoothing capacitor Cd. As a result, the DC voltage Vd is increased and controlled so that Vd * = Vd.
[0082]
Conversely, when Vd * <Vd, the output Iq * of the adder C2 decreases or becomes a negative value, and the active power Ps is regenerated from the DC smoothing capacitor Cd to the AC power supply SUP side. As a result, the direct-current voltage Vd is decreased and is controlled so that Vd * = Vd.
[0083]
In the apparatus shown in FIG. 1, a DC current Idc taken by a load is detected, a compensation amount IqFF = k1 · Idc is calculated by a feedforward compensator FF so that an effective current corresponding to the amount is supplied, and input to an adder C2. is doing. As a result, when the load suddenly changes, an input current (effective current) Iq corresponding to the load is supplied, and fluctuations in the applied voltage Vd of the DC smoothing capacitor Cd are suppressed.
[0084]
<Second Embodiment>
In this embodiment, in the power conversion device of FIG. 1, a reset circuit composed of a series circuit of a diode Dp and a resistor Rp is connected in parallel to the recovery current suppressing reactor Lp in order to reset the recovery current flowing therethrough. Is.
[0085]
The recovery current suppressing reactor Lp suppresses an excessive recovery current from flowing into each diode of the power diode rectifier REC when the self-extinguishing element of the voltage source self-excited power converter CNV is turned on. Usually, the inductance of the reactor Lp is about several tens of μH, which is about two orders of magnitude smaller than that of the AC reactor Ls. When a recovery current flows through the reactor Lp, it is necessary to reset the current once before the next switching, and a reset circuit is provided for the reset.
[0086]
In the circuit device of FIG. 1, for example, when the R-phase input current Ir is flowing through the power diode PD1, and the self-extinguishing element S4 is turned on, the recovery current of the diode PD1 is the DC smoothing capacitor Cd ( +) → Reactor Lp → Power diode PD1 → Self-extinguishing element S4 → Direct current smoothing capacitor Cd (−). Reactor Lp suppresses this current from becoming excessive. When the accumulated carriers in the diode PD1 disappear due to the recovery current, the diode PD1 is turned off. At that time, a voltage of VLP = Lp (di / dt) is generated at both ends of the reactor Lp due to the energy accumulated in the reactor Lp. As a result, a voltage of Vd + VLP is applied to the self-extinguishing element and the diode constituting the converter. At this time, the reset circuit composed of the diode Dp and the resistor Rp consumes the stored energy of the reactor Lp and plays a role of resetting the current. The time constant Tp of the reset circuit is given by Tp = Lp / Rp, where Lp is the inductance of the reactor Lp and Rp is the resistance value of the resistor Rp, and is preferably 1/3 or less of the switching period. When the self-excited converter is operated with one pulse, the power supply frequency fs is 50 Hz, and the switching cycle Tsw is Tsw = 1 / (6 · fs) = 1/300 [s] = 3.3 [ms]. Therefore, it is desirable to set Tp = 1 [ms] or less. If L = 50 μH and R = 0.1Ω, T = 0.5 [ms]. When the resistance R is increased, the voltage applied to the converter increases, and accordingly, the breakdown voltage of the element needs to be increased.
[0087]
As a circuit for resetting the recovery current flowing through the recovery current suppressing reactor Lp, FIG. 1 shows a series circuit of the diode Dp and the resistor Rp, but a DC voltage source may be prepared instead of the resistor Rp. The DC voltage source may be a battery or a large-capacity DC smoothing capacitor. Since energy is gradually stored in the DC voltage source, a circuit that consumes it or a circuit that regenerates power is often added.
[0088]
Thus, for example, the function of the recovery current suppression reactor Lp inserted on the DC side can be maintained by connecting a reset circuit including the diode Dp and the resistor Rp in parallel to the recovery current suppression reactor Lp.
[0089]
<Third Embodiment>
FIG. 3 shows an embodiment of the phase control circuit PHC in FIG. In FIG. 3, AD1 to AD3 are adders / subtracters provided for each phase, and PTN1 to PTN3 are pulse pattern generators similarly provided for each phase. The adders / subtractors AD1 to AD3 subtract the phase angle command value φ * from the phase signals θr, θs, θt to generate new phase signals θcr, θcs, θct. The new phase signals θcr, θcs, and θct change in synchronization with the power supply frequency with a periodic function of 0 to 2π. The pulse pattern generators PTN1 to PTN3 generate gate signals g1 to g6 for each phase so that a new pulse signal θcr, θcs, θct has a constant pulse pattern.
[0090]
Using the R phase as a representative example, the pulse pattern generator PTN1 stores the pulse pattern of the R phase elements S1 and S4 with respect to the phase signal θcr as a table function. FIG. 4 shows a waveform during one pulse operation. In the figure, Vr is an R-phase power supply voltage, θr is a phase signal synchronized with the power supply voltage Vr, and has a periodic function that varies between 0 and 2π. The new phase signal θcr = θr−φ * is a periodic function that changes between 0 and 2π, and is given as a signal delayed by φ * with respect to the signal of θr. That is, the following gate signal g1 (or g4) is output with respect to the input θcr. That is,
In the range of 0 ≦ θcr <π, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of π ≦ θcr <2π, g1 = 0, g4 = 1 (S1 off, S4 on)
It is.
[0091]
The AC side output voltage (R phase) Vcr of the self-excited power converter CNV is
When S1 is on (S4 is off), Vcr = + Vd / 2
When S1 is off (S4 is on), Vcr = −Vd / 2
It becomes. If the DC voltage Vd is constant, the amplitude value of the AC output voltage Vcr is constant. The phase of the fundamental wave Vcr * of the AC output voltage Vcr is delayed by the phase angle φ with respect to the power supply voltage Vs. The S phase and T phase are also offset by 120 ° to 240 ° from the R phase, respectively, but are given similarly.
[0092]
FIG. 5 shows an operation waveform of each part of the R phase when the self-excited power converter CNV is operated with the pulse pattern of FIG. For convenience of explanation, the input current Ir is drawn as a sine wave with the ripples omitted. FIG. 5 shows an operation waveform during powering operation. The fundamental wave of the AC output voltage Vcr of the converter is delayed by the phase angle φ with respect to the power supply voltage Vr. The input current Ir flows with a phase angle (φ / 2) with respect to the power supply voltage Vr. Here, IS1 and IS4 are currents of the R-phase self-extinguishing elements S1 and S4, ID1 and ID4 are currents of the high-speed diodes D1 and D4, and IPD1 and IPD4 are currents of the power diodes PD1 and PD4, respectively. It represents. The operation at that time will be described below with reference to FIG.
[0093]
Until the R-phase input current Ir changes from negative to positive, current flows through the power diode PD4. When the direction of the current Ir changes from this state, the element S4 is in the on state, so that the input current Ir flows through the recovery current suppressing reactor Ls and the element S4. Next, when the element S4 is turned off, the current Ir first flows through the high-speed diode D1 due to the effect of the wiring inductance. Since the forward drop voltage VFPD1 of the power diode PD1 is lower than the forward drop voltage VFD1 of the high speed diode D1, the input current Ir immediately shifts from the high speed diode D1 to the power diode PD1.
[0094]
The current flows through the power diode PD1 until the input current Ir is inverted again. After the input current Ir is inverted, the same operation as described above is performed between the element S1, the high speed diode D4, and the power diode PD1.
[0095]
Thus, according to this embodiment, most of the input current Ir during powering operation flows to the power diodes PD1 and PD4, so that it is possible to provide a power converter that has a small loss and a large overload capability.
[0096]
By reducing the direct wiring distance between the AC terminal of the power diode rectifier REC and the AC terminal of the self-excited converter CNV, the wiring inductance can be reduced, and almost all the current flowing through the high-speed diodes D1 to D6 can be reduced. Can be zero. Finally, the high speed diodes D1 to D6 can be omitted.
[0097]
The maximum current Imax cut off by the self-extinguishing elements S1 to S6 of the self-excited power converter CNV is, when the peak value of the input current is Ism,
Imax = Ism × sin (φ / 2)
It becomes. For example, when φ = 20 °,
Imax = 0.174 × Ism
It becomes. That is, it is only necessary to prepare a self-extinguishing element S1 to S6 having a capacity with a small breaking current, and a low-cost power conversion device can be provided.
[0098]
FIG. 6 shows operation waveforms during regenerative operation. IS1 and IS4 are currents of R-phase self-extinguishing elements S1 and S4, ID1 and ID4 are currents of high-speed diodes D1 and D4, and IPD1, IPD4 represents the current of the power diode. The fundamental wave of the AC output voltage Vcr of the converter is advanced by the phase angle φ with respect to the power supply voltage Vr. The input current Ir flows with a phase angle (φ / 2) with respect to the inversion value −Vr of the power supply voltage.
[0099]
When the R-phase input current Ir is negative and the element S1 is on (S4 is off), the input current Ir flows through the element S1. When the element S1 is turned off (S4 is turned on), the current Ir first flows through the high speed diode D4 due to the effect of the wiring inductance. Since the forward drop voltage VFPD4 of the power diode PD4 is lower than the forward drop voltage VFD4 of the high speed diode D4, the input current Ir immediately moves from the high speed diode D4 to the power diode PD4. When the input current Ir is inverted, a current flows through the element S4. When the element S4 is turned off in the same manner as described above, the current first moves to the high speed diode D1, and then immediately flows to the power diode PD1.
[0100]
During regenerative operation, the maximum current Imax that the self-extinguishing elements S1 to S6 cut off is when the peak value of the input current is Ism,
Imax = Ism × sin (φ / 2)
It becomes. For example, when φ = 20 °,
Imax = 0.174 × Ism
It becomes.
[0101]
As described above, most of the input current Ir during the regenerative operation flows through the self-extinguishing elements S1 to S6, but the cut-off current of the elements S1 to S6 can be small, and a low-cost power conversion device can be provided. it can.
[0102]
In electric railways, since power is supplied to a plurality of vehicles from one substation, generally the load during powering operation is heavy and the regenerative power is small. For example, 300% of the rated output is required as the overload withstand capability during powering operation, but normally the regenerative power only needs to have a rating of 100%. This power converter is suitable for a large overload capability during such powering operation.
[0103]
FIG. 7 shows an operation waveform at the time of transition from power running to regenerative operation. The phase angle φ of the AC output voltage Vcr of the power converter is changed from the delayed phase to zero with respect to the power supply voltage Vr. It is a thing. When the input current Ir is positive, the self-extinguishing element S4 is turned on (S1 is turned off), and the input current Ir flowing in the power diode PD1 is commutated to the element S4. At this time, the recovery current suppression reactor Lp arranged on the direct current side acts to suppress the recovery current IPD1re flowing in the power diode PD1. Without this recovery current suppressing reactor Lp, an excessive recovery current flows through the power diode PD1 and not only increases the loss but also destroys the diode PD1 and the self-extinguishing element S4. The same applies to the case where the self-extinguishing element S1 is turned on (S4 is turned off) when the input current Ir is negative, and the input current Ir flowing in the power diode PD4 is commutated to the element S1.
[0104]
By operating the self-excited converter CNV with one pulse, the number of times of switching is minimized and the converter efficiency is further improved. Moreover, the fundamental wave component of the AC side output voltage Vc is increased, and the voltage utilization factor of the self-excited converter is improved. In addition, since the converter power factor is operated at approximately 1, switching is performed only once near the zero point of the input current Is, and the cutoff current of the self-extinguishing element during power running operation and regenerative operation is Extremely small. As a result, a highly efficient and low cost power conversion device can be provided. Further, not interrupting a large current means switching close to soft switching, and therefore, EMI noise is reduced, and an environment-friendly power conversion device can be provided.
[0105]
<Fourth embodiment>
FIG. 8 shows an operation waveform when a three-pulse output is performed as the pulse pattern generator PTN1, and the R phase is illustrated. In the figure, Vr is an R-phase power supply voltage, θr is a phase signal synchronized with the power supply voltage Vr, and has a periodic function that varies between 0 and 2π. The new phase signal θcr = θr−φ * is a periodic function that changes between 0 and 2π, and is given as a signal delayed by φ * with respect to the signal of the phase signal θr. The pulse pattern of the R-phase elements S1 and S4 with respect to the phase signal θcr is
In the range of 0 ≦ θcr <θ1, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ1 ≦ θcr <θ2, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ2 ≦ θcr <π, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of π ≦ θcr <θ3, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ3 ≦ θcr <θ4, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ4 ≦ θcr <2π, g1 = 1, g4 = 0 (S1 on, S4 off)
It becomes.
[0106]
At this time, the AC side output voltage (R phase) Vcr of the self-excited power converter CNV is
When S1 is on (S4 is off), Vcr = + Vd / 2
When S1 is off (S4 is on), Vcr = −Vd / 2
It becomes. The phase of the fundamental wave Vcr * of the output voltage Vcr is delayed by the phase angle φ with respect to the power supply voltage Vr. S and T phases are given as well.
[0107]
In this case as well, the pulse pattern is fixed, and when the DC voltage Vd is constant, the fundamental peak value of the AC output voltage of the self-excited power converter CNV is constant.
[0108]
FIG. 9 shows an operation waveform of each part of the R phase when the self-excited power converter is operated with the pulse pattern of FIG. In order to simplify the description, the input current Ir is drawn as a sine wave with the ripples omitted. FIG. 9 shows an operation waveform during the power running operation. The fundamental wave of the AC output voltage Vcr of the converter is delayed by the phase angle φ with respect to the power supply voltage Vs. The input current Is flows with a phase angle (φ / 2) delayed from the power supply voltage Vs. Here, IS1 and IS4 represent currents of the R-phase self-extinguishing elements S1 and S4, ID1 and ID4 represent currents of the high-speed diodes D1 and D4, and IPD1 and IPD4 represent currents of the power diodes PD1 and PD4, respectively. ing. The operation at that time will be described below.
[0109]
Until the input current Ir changes from negative to positive, current flows through the power diode PD4. When the direction of the current Ir is changed from this state, the element S4 is in the on state, so that the input current Ir flows through the element S4. Next, when the element S4 is turned off, the current Ir first flows through the high-speed diode D1 due to the effect of the wiring inductance. Since the forward drop voltage VFPD1 of the power diode PD1 is lower than the forward drop voltage VFD1 of the high speed diode D1, the input current Ir immediately shifts from the high speed diode D1 to the power diode PD1.
[0110]
Next, when the element S4 is turned on again, the input current Ir flows through the element S4, and the currents of the power diode PD1 and the high speed diode D1 become zero. Further, when the element S4 is turned off at θ1 in FIG. 9, the current first flows to the high speed diode D1, and then the current moves to the power diode PD1 until the input current Ir is inverted again, as described above. The current flows through the power diode PD1. After the input current Ir is inverted, the same operation as described above is performed between the element S1, the high-speed diode D4, and the power diode PD4.
[0111]
Although the pulse pattern of FIG. 9 shows the case of 3 pulses, the maximum current Imax cut off by the self-extinguishing elements S1 to S6 is when the peak value of the input current is Ism,
Imax = Ism × sin (φ / 2 + θ1)
It becomes. However, θ2 <90 °. For example, when φ = 20 ° and θ2 = 10 °,
Imax = 0.342 × Ism
It becomes.
[0112]
Thus, according to the present embodiment, during power running, most of the current flows through the power diodes PD1 to PD6 having a low on-voltage, and a highly efficient conversion device can be achieved. Further, the cutoff current of the self-extinguishing elements S1 to S6 can be reduced, and the cost of the entire apparatus can be greatly reduced.
[0113]
FIG. 10 shows an operation waveform when the 5-pulse output operation is performed as the pulse pattern generator PTN1, and the R phase is illustrated. In the figure, Vr is an R-phase power supply voltage, θr is a phase signal synchronized with the power supply voltage Vr, and has a periodic function that varies between 0 and 2π. The new phase signal θcr = θr−φ * is a periodic function that changes between 0 and 2π, and is given as a signal delayed by φ * with respect to the θr signal. The pulse pattern of the R-phase elements S1 and S4 with respect to the phase signal θcr is as follows.
[0114]
In the range of 0 ≦ θcr <θ1, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ1 ≦ θcr <θ2, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ2 ≦ θcr <θ3, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ3 ≦ θcr <θ4, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ4 ≦ θcr <π, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of π ≦ θcr <θ5, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ5 ≦ θcr <θ6, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ6 ≦ θcr <θ7, g1 = 0, g4 = 1 (S1 off, S4 on)
In the range of θ7 ≦ θcr <θ8, g1 = 1, g4 = 0 (S1 on, S4 off)
In the range of θ8 ≦ θcr <2π, g1 = 0, g4 = 1 (S1 off, S4 on)
The AC side output voltage (R phase) Vcr of the self-excited power converter CNV is
When S1 is on (S4 is off), Vcr = + Vd / 2
When S1 is off (S4 is on), Vcr = −Vd / 2
It becomes. If the DC voltage Vd is constant, the amplitude value of the AC output voltage Vcr is constant. The phase of the fundamental wave Vcr * of Vcr is delayed by the phase angle φ with respect to the power supply voltage Vr. S and T phases are given as well.
[0115]
FIG. 11 shows an operation waveform of each part when the self-excited power converter is operated with the pulse pattern of FIG. 10 and shows the R phase. In order to simplify the description, the input current Ir is drawn as a sine wave with the ripples omitted.
[0116]
In FIG. 11, the fundamental wave of the AC output voltage Vcr of the converter is delayed by the phase angle φ with respect to the power supply voltage Vs. Therefore, the power converter is in a power running operation, and the input current Is flows with a phase angle (φ / 2) delayed with respect to the power supply voltage Vs. Here, the currents IS1 and Is4 are the currents of the R-phase self-extinguishing elements S1 and S4, ID1 and ID4 are the currents of the high-speed diodes D1 and D4, and the currents IPD1 and IPD4 are the current waveforms of the power diodes, respectively. It represents. The operation at that time will be described below using the apparatus shown in FIG.
[0117]
Until the input current Ir changes from negative to positive, current flows through the power diode PD4. When the direction of the current Ir is changed from this state, the element S4 is in the on state, so that the input current Ir flows through the element S4. Next, when the element S4 is turned off, the current Ir first flows through the high-speed diode D1 due to the effect of the wiring inductance. Since the forward drop voltage VFPD1 of the power diode PD1 is lower than the forward drop voltage VFD1 of the high speed diode D1, the input current Ir immediately moves from the high speed diode D1 to the power diode PD1.
[0118]
Next, when the element S4 is turned on again, the input current Ir flows through the element S4, and the currents of the power diode PD1 and the high speed diode D1 become zero. Further, when the element S4 is turned off, the current Ir first flows through the high speed diode D1, and the current immediately moves to the power diode PD1. The above operation is repeated according to the pulse pattern shown in FIG. 10, but after the element S4 is turned off (the element S1 is turned on) at the phase angle θ2 in FIG. 10, first, a current flows through the high-speed diode D1 as described above. Then, the current flows to the power diode PD1, and the current flows to the power diode PD1 until the input current Ir is inverted again. After the input current Ir is inverted, the same operation as described above is performed between the element S1, the high speed diode D4, and the power diode PD4.
[0119]
Although the pulse pattern of FIG. 11 shows the case of 5 pulses, the maximum current Imax cut off by the self-extinguishing elements S1 to S6 is when the peak value of the input current is Ism,
Imax = Ism × sin (φ / 2 + θ2)
It becomes. However, θ2 <90 °. For example, when φ = 20 ° and θ2 = 15 °,
Imax = 0.42 × Ism
It becomes.
[0120]
By increasing the number of pulses, the harmonic component of the input current Ir can be reduced and the current pulsation can be reduced. However, on the other hand, the maximum value Imax of the cutoff current of the self-extinguishing element is increased. There is. As will be described later, it is desirable to reduce the input current harmonics by multiplexing power converters, etc., and to operate with as few pulses as possible.
[0121]
When the self-excited converter CNV is controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current Is becomes small. However, because the converter power factor is operated near 1 as described above. Switching is performed in the vicinity of the zero point of the current Is, and the cut-off current of the self-extinguishing element constituting the self-excited converter CNV can be small. As a result, it is possible to provide a power conversion device that can regenerate power, has a high power factor, is highly efficient, and is low in cost.
[0122]
<Fifth embodiment>
FIG. 12 shows another embodiment of the control device of the device of the present invention. In this embodiment, the voltage command value Vd * in the control device of FIG. 1 is changed by the arithmetic circuit CAL according to the peak value Vsm of the power supply voltage or the peak value Ism of the input current. As one control method, the arithmetic circuit CAL gives the DC voltage command value Vd * in proportion to the power supply voltage peak value Vsm.
[0123]
FIG. 13 shows a voltage / current vector diagram on the AC power supply side when the amplitude value of the power supply voltage Vs varies when the DC voltage Vd is controlled to be constant. When Vs = Vc, the phase angle φ = 0 and the input current Is becomes zero. On the other hand, when Vs <Vc, the leading current flows when φ = 0. On the contrary, when Vs> Vc, a delay current flows when φ = 0. When the power supply voltage Vs fluctuates, the fundamental wave crest value of the converter output voltage Vc can always be matched with the crest value of the power supply voltage Vs by adjusting the DC voltage Vd accordingly. Thereby, it is possible to prevent useless reactive current from being taken from the power source when the phase angle φ = 0.
[0124]
<Sixth Embodiment>
In the control device of FIG. 12, the arithmetic circuit CAL calculates the DC voltage command value Vd *
Vd * = k · √ {Vsm ² + (ΩLs ・ Ism) ² }
Shall be given as Here, Vsm represents a power supply voltage peak value, ω represents a power supply angular frequency, Ls represents an inductance value of the AC reactor Ls, and Ism represents a peak value of the input current Is.
[0125]
In this control method, not only the DC voltage command value Vd * is changed depending on the magnitude of the power supply voltage Vs, but also the Vd * is adjusted in relation to the input current peak value Ism.
[0126]
FIG. 14 shows a voltage / current vector diagram on the AC side at this time. The converter output voltage is
Vc = √ {Vs ² + (ΩLs · Is) ² }
Keep the relationship. As a result, the power supply voltage vector Vs and the applied voltage (= jωLs · Is) of the AC reactor Ls always maintain a quadrature relationship, and the input current Is is in phase (or in reverse phase) with the power supply voltage Vs. Rate = 1.
[0127]
FIG. 15 shows the relationship of the DC voltage command value Vd * to the input current peak value Ism. The DC voltage command value Vd * is increased as the current Ism increases.
[0128]
<Seventh embodiment>
In the control circuit of FIG. 12, the arithmetic circuit CAL calculates the DC voltage command value Vd *
Vd * = k · √ {Vsm ² -(ΩLs ・ Ism) ² }
Shall be given as Here, Vsm represents the power supply voltage peak value, ω represents the power supply angular frequency, Ls represents the inductance value of the AC reactor, and Ism represents the input current peak value.
[0129]
In this control method, not only the DC voltage command value Vd * is changed depending on the magnitude of the power supply voltage Vs, but also the Vd * is adjusted in relation to the input current peak value Ism.
[0130]
FIG. 16 shows a voltage / current vector diagram on the AC side at this time. The converter output voltage is
Vc = √ {Vs ² -(ΩLs ・ Is) ² }
Keep the relationship. As a result, the converter output voltage vector Vc and the applied voltage (= jωLs · Is) of the AC reactor Ls always maintain a quadrature relationship, and the input current Is is in phase (or in reverse phase) with the converter output voltage Vc. Thus, the converter power factor becomes 1.
[0131]
FIG. 17 shows the relationship of the DC voltage command value Vd * with respect to the input current peak value Ism, and shows that the DC voltage command value Vd * decreases as the current Ism increases.
[0132]
FIG. 18 shows an operation waveform when the converter is operated in the 1-pulse mode with a converter power factor of 1. For the convenience of explanation, the input current Ir is drawn as a sine wave with the ripples omitted. In the figure, IS1 and IS4 represent currents of the R-phase self-extinguishing elements S1 and S4, ID1 and ID4 represent currents of the high-speed diodes D1 and D4, and IPD1 and IPD4 represent current waveforms of the power diodes PD1 and PD4. Respectively.
[0133]
FIG. 18 shows a waveform during powering operation. The fundamental wave of the AC output voltage Vcr of the converter is delayed by the phase angle φ with respect to the power supply voltage Vs. The input current Ir is in phase with the AC output voltage Vcr of the converter and flows with a phase angle φ delayed from the power supply voltage Vr.
[0134]
In the 1-pulse mode, when the input current Ir is zero, the self-extinguishing element S1 or S4 is turned on / off, so that the interruption current of the element becomes zero. The same applies to regenerative operation. In other words, by operating with the converter power factor = 1, it becomes possible to operate with the interruption current of the self-extinguishing element constituting the self-excited converter being zero, and the converter cost can be greatly reduced. It becomes. In addition, zero current switching, that is, soft switching can be performed, and the problems of EMI noise and inductive failure that are currently problematic in hard switching can be solved.
[0135]
<Eighth Embodiment>
FIG. 19 shows another embodiment of the apparatus of the present invention. In this embodiment, two power converters that combine a power diode rectifier REC and a voltage-type self-excited power converter CNV are prepared, and two sets of secondary windings having a phase difference of 30 ° between them are prepared. Using the three-phase transformer TR, the power converter is configured to perform parallel multiplex operation on the AC side and to connect in parallel on the DC side. Here, the diode rectifier REC, the voltage source self-excited power converter CNV, the AC reactor Ls, and the recovery current suppression reactor Lp described in FIG. It represents belonging. The transformer TR interposed between the AC power supply terminals R, S, T and the AC reactors LS1, LS2 has two sets of secondary windings, and one of the secondary windings is a star connection (Y connection). ), And the other secondary winding is a triangular connection (Δ connection), and there is a phase difference of 30 ° between the output voltages of both. One secondary winding of the transformer TR supplies power to the first group of power converters, and the other secondary winding supplies power to the second group of power converters. Both power converters CNV1 and CNV2 are connected in parallel on the DC side, and the DC terminals thereof are connected to a common DC smoothing capacitor Cd and a load device LOAD. The load device LOAD is a collective representation of the inverter INV and the AC motor M.
[0136]
FIG. 20 shows an embodiment of a control device that controls the power conversion device of FIG. 19, and is used in common for both groups up to the generation of the active current command value Iq *. Divided into The constituent elements of each group are the same as those in FIG. 1, but here again, those in the first group and those in the second group are distinguished by the suffix 1 or 2. Finally, the first controller outputs gate signals g11 to g16 for the self-extinguishing element of the first power converter CNV1, and the second control unit outputs the self-extinguishing of the second power converter CNV2. Gate signals g21 to g26 for the element are output.
[0137]
For example, the R-phase input currents (secondary currents of the transformer TR) Ir1 and Ir2 of the two sets of power converters are controlled independently, but both command values Iq * are the same, so they are controlled to substantially the same value. . As a result, the harmonics of the primary current of the transformer TR cancel each other, and operation with less current ripple can be performed. When the parallel multiple operation is performed by combining three or more power conversion devices, the primary current ripple of the transformer TR can be further reduced.
[0138]
This device can increase the capacity of the conversion device and reduce the harmonic component of the input current Is supplied from the AC power supply, thereby providing high efficiency with excellent overload capability and power regeneration. -A low-cost large-capacity power converter can be provided.
[0139]
<Ninth embodiment>
The present embodiment adjusts the phase angle φ with respect to the voltage Vs of the AC power supply by operating n voltage source self-excited power converters CNV1 to CNVn in a constant pulse pattern in the power conversion device of the eighth embodiment. Thus, the AC input current Is is controlled, and the voltage Vd of the DC smoothing capacitor Cd is controlled. The voltage type self-excited power converters CNV1 to CNVn operate with a constant pulse pattern and perform switching in synchronization with the voltage Vs of the AC power supply. If the DC voltage Vd is constant, the amplitude values of the AC output voltages Vc1 to Vcn of the self-excited power converters CNV1 to CNVn are constant. In this state, by changing the phase angle φ of the output voltages Vc1 to Vcn with respect to the power supply voltage Vs, the voltage applied to the AC reactors Ls1 to Lsn changes, and the input current Is can be adjusted. By increasing the phase angle φ of the output voltages Vc1 to Vcn of each converter with respect to the power supply voltage Vs in the delay direction, the effective power Ps supplied from the AC power supply increases. Conversely, when the phase angle φ is increased in the advance direction, the active power Ps is regenerated to the AC power source.
[0140]
When the self-excited converters CNV1 to CNVn are controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current Is becomes small. However, since the converter power factor is close to 1, the zero point of the current Is Switching is performed in the vicinity, and the cut-off current of the self-extinguishing elements constituting the self-excited converters CNV1 to CNVn can be small. Thereby, the harmonic component of the input current Is is small, power regeneration is possible, and a high-power factor / high-efficiency, low-cost power conversion device can be provided.
[0141]
<Tenth Embodiment>
In this embodiment, in the power conversion device of the eighth embodiment, n voltage-type self-excited power converters CNV1 to CNVn are operated in a one-pulse mode synchronized with the frequency of the AC power supply SUP, and the voltage of the AC power supply The AC input current Is is controlled by adjusting the phase angle φ with respect to Vs, and the voltage Vd of the DC smoothing capacitor Cd is controlled.
[0142]
By operating each voltage type self-excited power converter CNV1 to CNVn in the 1-pulse mode, switching loss can be reduced and the voltage utilization factor of the self-excited converter can be improved. Further, since the self-excited converter is switched near the zero point of the input current Is, the cutoff current of the self-extinguishing element can be reduced. As a result, it is possible to provide a power conversion device that has excellent overload capability, low cost, high efficiency, and large capacity.
[0143]
<Eleventh embodiment>
FIG. 21 shows still another embodiment of the device of the present invention. The feature of this embodiment is that the DC side of the first and second voltage source self-excited power converters CNV1 and CNV2 is connected in series to supply power to a common load device LOAD. The other configuration is the same as that of FIG.
[0144]
FIG. 22 shows an embodiment of the control device of the apparatus of FIG. Self-excited power converters CNV1 and CNV2 perform a control operation so that voltages Vd1 and Vd2 of DC smoothing capacitors Cd1 and Cd2 respectively coincide with command value Vd *. The comparator C11 compares the voltage detection value Vd1 with the voltage command value Vd *, and the deviation εv1 is integrated or proportionally amplified by the voltage control compensation circuit Gv1 (S) and input to one input terminal of the adder C21. . Similarly, the comparator C12 compares the voltage detection value Vd2 with the voltage command value Vd *, and the deviation εv2 is integrated or proportionally amplified by the voltage control compensation circuit Gv2 (S), and is added to one input terminal of the adder C22. On the other hand, the DC current Idv consumed by the load LOAD is detected and input to the other input terminals of the adders C21 and C22 via the common feedforward compensator FF. The output of the adder C21 becomes the command value Iq1 * of the active current supplied from the power supply SUP to the first power converter (REC1 + CNV1), and the output of the adder C22 is sent from the power supply SUP to the second power converter (REC2 + CNV2). The command value Iq2 * of the effective current to be supplied is obtained. Others are the same as those of FIG.
[0145]
Voltage-type self-excited power converters CNV1 and CNV2 control the input current by controlling the phase angle φ1, φ2 with respect to the power supply voltage with a constant pulse pattern (1 pulse, 3 pulses, 5 pulses, etc.) synchronized with the power supply voltage. To do.
[0146]
The input currents (secondary currents of the transformer TR) Ir1 and Ir2 (R phase) of the two sets of power converters are controlled independently, but in the steady state, the DC voltages Vd1 and Vd2 are substantially the same, and the effective current command Since the values Iq1 * and Iq2 * are substantially equal, the input currents Is1 and Is2 are controlled to be substantially the same value. As a result, the harmonics of the primary current of the transformer cancel each other, and operation with less current ripple can be performed. When the parallel multiple operation is performed by combining three or more power conversion devices, the primary current ripple of the transformer TR can be further reduced.
[0147]
This device can increase the capacity of the conversion device, increase the DC output voltage Vd, and reduce the harmonic component of the input current Is supplied from the AC power supply. It is possible to provide a high-efficiency, low-cost, large-capacity power conversion device that can regenerate power.
[0148]
<Twelfth embodiment>
The feature of this embodiment is that in the power conversion device of the eleventh embodiment, n voltage-type self-excited power converters CNV1 to CNVn are operated with a constant pulse pattern, and the phase angle φ with respect to the voltage Vs of the AC power supply is set. The adjustment is to control the AC input current Is and to control the voltages Vd1 to Vdn applied to the DC smoothing capacitors Cd1 to Cdn.
[0149]
The voltage type self-excited power converters CNV1 to CNVn perform switching in synchronization with the voltage Vs of the AC power supply with a constant pulse pattern. If the DC voltage Vd is constant, the amplitude values of the AC output voltages Vc1 to Vcn of the self-excited converters CNV1 to CNVn are constant. In this state, by changing the phase angle φ of the output voltages Vc1 to Vcn with respect to the power supply voltage Vs, the voltage applied to the AC reactors Ls1 to Lsn changes, and the input current of each voltage source self-excited power converter CNV1 to CNVn Can be adjusted. When the self-excited converters CNV1 to CNVn are controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current Is becomes small. By operating the converter power factor close to 1, Switching is performed near the zero point of Is, and the cutoff current of the self-extinguishing elements constituting the self-excited converters CNV1 and CNV2 can be reduced.
[0150]
By increasing the phase angle φ of the output voltages Vc1 to Vcn of each converter with respect to the power supply voltage Vs in the delay direction, the effective power Ps supplied from the AC power supply increases. Conversely, when the phase angle φ is increased in the advance direction, the active power Ps is regenerated to the AC power source. Self-excited converters CNV1 to CNVn control so that voltages Vd1 to Vdn of DC smoothing capacitors Cd1 to Cdn are substantially constant. As a result, the sum voltage Vd0 = Vd1 + Vd2 + ... + Vdn is controlled to be constant. As a result, the DC output voltage can be increased, the harmonic component of the input current Is is small, power regeneration is possible, and a high power factor, high efficiency, and low cost power conversion device is provided. it can.
[0151]
<Thirteenth embodiment>
In this embodiment, in the power conversion device of the eleventh embodiment, n voltage-type self-excited power converters CNV1 to CNVn are operated in a one-pulse mode synchronized with the frequency of the AC power supply SUP, and the voltage Vs of the AC power supply is set. Is adjusted to control the input currents of the voltage-type self-excited power converters CNV1 to CNVn and the voltages Vd1 to Vdn applied to the DC smoothing capacitors Cd1 to Cdn.
[0152]
By operating each of the voltage source self-excited power converters CNV1 to CNVn in the one-pulse mode, the switching loss can be reduced and the voltage utilization rate of the self-excited converter can be improved. Further, since the self-excited converter is switched near the zero point of the input current Is, the cutoff current of the self-extinguishing element can be reduced. As a result, it is possible to provide a power conversion device that has excellent overload capability, low cost, high efficiency, and large capacity.
[0153]
<Fourteenth embodiment>
FIG. 23 shows still another embodiment of the present invention. A feature of this embodiment is that the primary windings are connected in series instead of one transformer TR having two sets of secondary windings in the apparatus of FIG. 19 and have a phase difference of 30 ° from each other. By using two three-phase transformers TR1 and TR2 that output voltage to perform series multiplex operation, and using the leakage inductance of the two transformers, the AC shown in FIG. The reactors Ls1 and Ls2 are omitted. Of course, in the same manner as in FIG. 19, even if AC reactors Ls1 and Ls2 are provided outside, the same principle is obtained.
[0154]
FIG. 24 shows an embodiment of the control device of the device of FIG. Here, the steps from the adder C1 to the current control compensation circuit Gi (S) are the same as those in FIG. 1, and the phase control circuits PHC1, PHC2 and the subsequent branches are divided into two groups. The phase control circuits PHC1 and PHC2 generate gate signals g11 to g16 and g21 to g26 for both power converters CNV1 and CNV2 using the common phase angle command value φ * already described.
[0155]
The voltage-type self-excited power converters CNV1 and CNV2 control the input current Ir, Is by controlling the phase angle φ with respect to the power supply voltage with a constant pulse pattern (1 pulse, 3 pulses, 5 pulses, etc.) synchronized with the power supply voltage. , It is controlled. In this device, since the two transformers TR1 and TR2 are connected in series on the primary side, the input currents of the two power converters (REC1 + CNV1 and REC2 + CNV2) are the same, resulting in a current with less harmonics. .
[0156]
Although the example using two power converters has been described above, it goes without saying that a serial multiple connection operation can be performed using three or more power converters.
[0157]
According to this device, it is possible to increase the capacity of the conversion device and reduce the harmonic component of the input current Is supplied from the AC power supply. In particular, there is an advantage that harmonic components of the AC side input current flowing through each converter can be reduced by serial multiple operation, and the control pulses of the self-excited power converters CNV1 to CNVn can be reduced. Moreover, the conventional AC reactor can be omitted by using the leakage inductance of the three-phase transformer. As a result, it is possible to provide a high-efficiency, low-cost, large-capacity power conversion device that is excellent in overload capability and capable of power regeneration.
[0158]
<Fifteenth embodiment>
In this embodiment, in the power conversion device of the fourteenth embodiment, n voltage-type self-excited power converters CNVl to CNVn are operated in a constant pulse pattern to adjust the phase angle φ with respect to the voltage Vs of the AC power supply. Thus, the AC input current Is is controlled, and the voltage Vd applied to the DC smoothing capacitor Cd is controlled.
[0159]
The voltage type self-excited power converters CNV1 to CNVn perform switching in synchronization with the voltage Vs of the AC power supply with a constant pulse pattern. If the DC voltage Vd is constant, the amplitude values of the AC output voltages Vc1 to Vcn of the self-excited converters CNV1 to CNVn are constant. In this state, by changing the phase angle φ of the output voltages Vc1 to Vcn with respect to the power supply voltage Vs, the voltage applied to the leakage inductance of the transformer changes and the input current Is can be adjusted. When the self-excited converters CNV1 to CNVn are controlled with a constant pulse pattern, the switching pattern is determined so that the harmonic component of the input current Is becomes small. By operating the converter power factor close to 1, Switching is performed near the zero point of Is, and the cutoff current of the self-extinguishing elements constituting the self-excited converters CNV1 to CNVn can be reduced.
[0160]
By increasing the phase angle φ of the output voltages Vc1 to Vcn of each converter with respect to the power supply voltage Vs in the delay direction, the effective power Ps supplied from the AC power supply increases. Conversely, when the phase angle φ is increased in the advance direction, the active power Ps is regenerated to the AC power source.
[0161]
Self-excited converters CNV1 to CNVn control input current Is such that voltage Vd applied to DC smoothing capacitor Cd is substantially constant. Thereby, the harmonic component of the input current Is is small, power regeneration is possible, and a high-power factor / high-efficiency, low-cost power conversion device can be provided.
[0162]
<Sixteenth Embodiment>
In this embodiment, in the power conversion device of the fourteenth embodiment, n voltage-type self-excited power converters CNV1 to CNVn are operated in a one-pulse mode synchronized with the frequency of the AC power supply SUP, and the voltage of the AC power supply The AC input current Is is controlled by adjusting the phase angle φ with respect to Vs, and the voltage Vd applied to the DC smoothing capacitor Cd is controlled.
[0163]
In the present embodiment, the self-excited converters CNV1 to CNVn are operated with a constant pulse pattern as in the fifteenth embodiment, but the number of pulses is one. Naturally, if the DC voltage Vd is constant, the amplitude values of the AC side output voltages Vc1 to Vcn of the self-excited converters CNV1 to CNVn are constant. The input current Is is controlled by adjusting the phase angle φ of the sum voltage of the AC side output voltages Vc1 to Vcn of the self-excited converters CNV1 to CNVn with respect to the power supply voltage Vs. When φ = 0, Is = 0 In order to achieve this, it is necessary that the peak value of the power supply voltage Vs and the fundamental peak value of the sum voltage of the converter output voltages Vc1 to Vcn be the same. Since the DC voltage Vd is determined by the load side requirements, etc., the secondary side voltages of the three-phase transformers TR1 to TRn are made the same as the fundamental wave components of the AC side output voltages Vc1 to Vcn of the self-excited converters CNV1 to CNVn. Adjust the values so that
[0164]
By operating the self-excited converters CNV1 to CNVn with one pulse, the number of times of switching can be minimized and the converter efficiency can be further improved. Further, the fundamental wave components of the AC side output voltages Vc1 to Vcn are increased, and the voltage utilization rates of the self-excited converters CNV1 to CNVn are improved. In addition, since the converter power factor is operated at approximately 1, switching is performed only once near the zero point of the input current Is, and the cutoff current of the self-extinguishing element during power running operation and regenerative operation is Extremely small. As a result, a highly efficient and low cost power conversion device can be provided. Further, not interrupting a large current means that it is close to soft switching, and EMI noise is reduced, and an environment-friendly power conversion device can be provided.
[0165]
<Seventeenth embodiment>
In this embodiment, in the power conversion devices of the eighth to sixteenth embodiments, the recovery current suppression reactors Lp1 to Lpn are reset for resetting a recovery current composed of a series circuit of diodes Dp1 and Dp2 and resistors Rp1 and Rp2. The circuit is connected in parallel.
[0166]
In the present embodiment, in the power converters of the eighth to sixteenth embodiments, a reset circuit for resetting the recovery current flowing through these reactors is added to the recovery current suppressing reactors Lp1 to Lpn, respectively. . Each reset circuit is composed of a series circuit of diodes Dp1 to Dpn and resistors Rp1 to Rpn.
[0167]
The recovery current suppressing reactors Lp1 to Lpn suppress excessive current flowing into each diode of the power diode rectifiers REC1 to RECn when the self-extinguishing elements of the voltage type self-excited power converters CNV1 to CNVn are turned on. Have a role to play. Normally, the reactors Lp1 to Lpn have an inductance value of several tens of μH. When a recovery current flows through the reactors Lp1 to Lpn, it is necessary to reset the current once before the next switching. Therefore, a reset circuit for resetting the recovery current once is connected in parallel to the reactors Lp1 to Lpn.
[0168]
When the recovery current flowing through the power diode disappears, a voltage of VLP = Lp (di / dt) is generated in the reactors Lp1 to Lpn. As a result, as a result, a voltage of Vd + VLP is applied to the self-extinguishing element and the diode constituting the converter. At this time, the reset circuit including the diode and the resistor consumes the energy stored in each of the reactors Lp1 to Lpn and serves to reset the current. The time constant Tp of the reset circuit is given by Tp = Lp / Rp, where Lp is the inductance of the reactor and Rp is the resistance value of the resistor, and is preferably 1/3 or less of the switching period. When the self-excited converter is operated with one pulse, if the power supply frequency fs is 50 Hz, the switching cycle Tsw is Tsw = 1 / (6 · fs) = 1/300 [s] = 3.3 [ms]. Become. Therefore, it is desirable to set Tp = 1 [ms] or less. If Lp = 50 μH and Rp = 0.1Ω, then Tp = 0.5 [ms]. When the resistance value Rp is increased, the voltage applied to the converter increases, and the breakdown voltage of the element needs to be increased accordingly.
[0169]
As a circuit for resetting the recovery current flowing through the recovery current suppressing reactors Lp1 to Lpn, a series circuit of a diode and a resistor is shown as an embodiment, but a DC voltage source may be prepared instead of the resistor. The DC voltage source may be a battery or a large-capacity DC smoothing capacitor. Since energy is gradually stored in the DC voltage source, a circuit that consumes it or a circuit that regenerates power is often added.
[0170]
Thus, for example, by connecting a reset circuit including a diode and a resistor in parallel to the recovery current suppression reactor, the function of the recovery current suppression reactor inserted on the DC side can be maintained.
[0171]
<Eighteenth embodiment>
In this embodiment, in the power converters of the eighth to seventeenth embodiments, n voltage-type self-excited power converters CNV1 to CNVn are adapted to change in the power supply voltage Vs when the voltage Vs of the AC power supply fluctuates. Thus, the command value of the voltage Vd applied to the DC smoothing capacitor Cd is changed and controlled.
[0172]
When n voltage-type self-excited power converters CNV1 to CNVn are operated with one pulse or a constant pulse pattern, the amplitude value of the AC side output voltage Vc of these power converters CNV1 to CNVn is constant, and the power supply voltage Vs is When it becomes higher, converters CNV1 to CNVn become delayed power factor operation, and when power supply voltage Vs becomes lower, converters CNV1 to CNVn become advanced power factor operation. As the power factor decreases, the phase difference between the AC output voltage Vc and the input current Is of the self-excited power converters CNV1 to CNVn increases, and the cutoff current of the self-extinguishing element constituting the self-excited power converter increases. turn into. Therefore, by adjusting the voltage Vd applied to the DC smoothing capacitor Cd according to the amplitude value of the power supply voltage Vs, control is always performed so that | Vs | = | Vc |. Thereby, it is possible to prevent an extreme decrease in the power source power factor or the converter power factor, and it is possible to prevent an increase in the cutoff current of the self-extinguishing element.
[0173]
<Nineteenth embodiment>
In this embodiment, in the power converters of the eighth to eighteenth embodiments, n voltage-type self-excited power converters CNV1 to CNVn have an angular frequency of AC power supply SUP as ω, a power supply voltage as Vs, and an input current. Is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor Cd is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
It controls to become.
[0174]
The voltage Vd applied to the DC smoothing capacitor Cd by n self-excited power converters CNV1 to CNVn is
Vd = k · √ {Vs ² + (Ω ・ Ls ・ Is) ² }
Thus, the phase of the input current Is can be matched to the phase of the power supply voltage Vs, and the operation with the power source power factor = 1 can be performed. This effect is the same in regenerative operation. As a result, it is possible to provide a power conversion device that is excellent in overload resistance, low cost, and high power factor.
[0175]
<20th Embodiment>
In this embodiment, in the power converters of the eighth to eighteenth embodiments, n voltage-type self-excited power converters CNV1 to CNVn have an angular frequency of AC power supply SUP as ω, a power supply voltage as Vs, and an input current. Is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the voltage Vd applied to the DC smoothing capacitor Cd is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
It controls to become.
[0176]
The voltage Vd applied to the DC smoothing capacitor Cd by n self-excited power converters CNV1 to CNVn is
Vd = k · √ {Vs ² -(Ω ・ Ls ・ Is) ² }
The phase angle φ of the input current Is with respect to the power supply voltage Vs can be made to substantially coincide with the phase angle φ of the AC output voltage Vc of the self-excited power converters CNV1 to CNVn. That is, the phase of the input current Is and the converter output voltage Vc are matched, and the converter power factor = 1 can be operated. As a result, the cut-off current of the self-extinguishing element constituting the self-excited converter CNV can be reduced, and the converter capacity can be reduced. This effect is the same in the regenerative operation. Thereby, it is excellent in overload tolerance, can provide a low-cost and highly efficient power converter device.
[0177]
【The invention's effect】
As described above in detail, according to the power conversion device of the present invention, it is possible to provide a power conversion device that is capable of power regeneration, has excellent overload capability, and is low in cost and high efficiency.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a power converter of the present invention.
FIG. 2 is an AC side voltage / current vector diagram for explaining a control operation of the apparatus of FIG.
FIG. 3 is a control block diagram for explaining a phase control operation of the apparatus of FIG. 1;
4 is a time chart for explaining a phase control operation of the apparatus of FIG. 1; FIG.
FIG. 5 is an operation waveform diagram of each part for explaining a control operation during the power running operation of the apparatus of FIG. 1;
6 is an operation waveform diagram of each part for explaining a control operation during a regenerative operation of the apparatus of FIG. 1;
7 is an operation waveform diagram of each part for explaining a control operation in a process from a power running operation to a regenerative operation of the apparatus of FIG. 1;
8 is another time chart for explaining the phase control operation of the apparatus of FIG. 1. FIG.
FIG. 9 is an operation waveform diagram for each part for explaining another control operation during the power running operation of the apparatus of FIG. 1;
10 is still another time chart for explaining the phase control operation of the apparatus of FIG. 1. FIG.
FIG. 11 is an operation waveform diagram of each part for explaining still another control operation during the power running operation of the apparatus of FIG. 1;
FIG. 12 is a block diagram showing an embodiment of another control circuit of the device of the present invention.
FIG. 13 is an AC side voltage / current vector diagram for explaining the operation of the device of the present invention.
FIG. 14 is an AC side voltage / current vector diagram for explaining a control operation of the device of the present invention.
FIG. 15 is a characteristic diagram for explaining a control operation of the device of the present invention.
FIG. 16 is an AC side voltage / current vector diagram for explaining another control operation of the device of the present invention;
FIG. 17 is a characteristic diagram for explaining another control operation of the device of the present invention.
FIG. 18 is an operation waveform diagram for explaining another control operation of the device of the present invention.
FIG. 19 is a main circuit configuration diagram showing another embodiment of the device of the present invention.
20 is a configuration diagram showing an embodiment of a control circuit of the apparatus shown in FIG. 19;
FIG. 21 is a main circuit configuration diagram showing still another embodiment of the device of the present invention.
22 is a configuration diagram showing an embodiment of a control circuit of the apparatus of FIG. 21. FIG.
FIG. 23 is a main circuit configuration diagram showing still another embodiment of the device of the present invention.
24 is a configuration diagram showing an embodiment of a control circuit of the apparatus of FIG. 23. FIG.
FIG. 25 is a configuration diagram of a conventional pulse width modulation control converter capable of power regeneration.
[Explanation of symbols]
SUP AC power supply
REC Power diode rectifier
CNV Voltage type self-excited power converter
Ls AC reactor
Lp Re-force burr current suppression reactor
Cd DC smoothing capacitor
LOAD load
C1, C3 comparator
C2 adder
Gv (S) voltage control compensation circuit
Gi (S) current control compensation circuit
FF feedforward compensator
A 3-phase / dq coordinate conversion circuit
PLL power supply synchronous phase detection circuit
PHC phase control circuit

Claims (20)

A power diode rectifier having an AC terminal connected to an AC power source through an AC reactor, a voltage type self-excited power converter in which the AC terminal is directly connected to the AC terminal of the power diode rectifier, and the voltage type A power converter comprising: an excitation power converter; and a DC smoothing capacitor connected between a DC common terminal of the power diode rectifier via a recovery current suppressing reactor and connecting a load device in parallel. The power converter according to claim 1, wherein a reset circuit for resetting a recovery current flowing through the reactor is connected in parallel to the recovery current suppressing reactor. 3. The power according to claim 1, wherein the voltage source self-excited power converter operates with a constant pulse pattern and controls an input current by adjusting a phase angle with respect to a voltage of the AC power supply. Conversion device. The voltage-type self-excited power converter operates in a one-pulse mode synchronized with the frequency of the AC power supply, and controls an input current by adjusting a phase angle with respect to the voltage of the AC power supply. The power converter according to 1 or 2. When the voltage of the AC power supply fluctuates, the voltage type self-excited power converter performs a control operation by changing a command value of the voltage applied to the DC smoothing capacitor in accordance with a change in the voltage of the power supply. The power converter according to any one of claims 1 to 4. The voltage-type self-excited power converter has the DC smoothing capacitor when the angular frequency of the AC power supply is ω, the power supply voltage is Vs, the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k. The voltage Vd applied to
Vd = k · √ {Vs ² + (ω · Ls · Is) ² }
The power conversion device according to claim 1, wherein control is performed so that In the voltage-type self-excited power converter, when the angular frequency of the AC power supply is ω, the power supply voltage is Vs, the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k, the DC smoothing capacitor The voltage Vd applied to
Vd = k · √ {Vs ² − (ω · Ls · Is) ² }
The power conversion device according to claim 1, wherein control is performed so that A three-phase transformer having a primary winding connected to a three-phase AC power source and having n sets of secondary windings having a predetermined phase difference, and an AC reactor on each secondary winding of the three-phase transformer N power diode rectifiers having AC terminals connected thereto, and n voltage-type self-excited power converters in which the AC side terminals are directly connected to the AC terminals of the n power diode rectifiers, The n voltage-type self-excited power converters and a DC smoothing capacitor connected to a DC common terminal of the n power diode rectifiers via a recovery current suppressing reactor and connecting a load device in parallel. A power conversion device. The n voltage-type self-excited power converters operate with a constant pulse pattern, and control the AC input current by adjusting the phase angle with respect to the voltage of the AC power supply to be applied to the DC smoothing capacitor. The power conversion device according to claim 8, wherein the power conversion device is controlled. The n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power source, and control the AC input current by adjusting the phase angle with respect to the voltage of the AC power source to control the DC current. The power converter according to claim 8, wherein a voltage applied to the smoothing capacitor is controlled. A three-phase transformer is connected to a three-phase AC power source, and a primary phase is connected to each other, and a secondary phase of the three-phase transformer is connected to each secondary winding via an AC reactor. N power diode rectifiers having AC terminals connected thereto, n voltage-type self-excited power converters having AC terminals directly connected to AC terminals of the n power diode rectifiers, A voltage source self-excited converter and n DC smoothing capacitors connected to a DC common terminal of each of the power diode rectifiers via a recovery current suppressing reactor, wherein the n DC smoothing capacitors are A power conversion device that is connected in series, and load devices are connected to both ends of the series connection. The n voltage-type self-excited power converters operate with a constant pulse pattern, and control the input current of each voltage-type self-excited power converter by adjusting the phase angle with respect to the voltage of the AC power source. The power converter according to claim 11, wherein a voltage applied to the DC smoothing capacitor is controlled. The n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power source, and adjust the phase angle with respect to the voltage of the AC power source to adjust the voltage type self-excited power converter. The power converter according to claim 11, wherein an input current is controlled to control a voltage applied to the DC smoothing capacitor. N three-phase transformers configured such that a primary winding is connected in series for each phase with respect to a three-phase AC power source, and an output voltage of the secondary winding has a predetermined phase difference, and these n units N power diode rectifiers with a three-phase bridge connection in which an AC terminal is connected to each secondary winding of the three-phase transformer, and an AC terminal directly connected to the AC terminals of these n power diode rectifiers N-type three-phase bridge-connected voltage-type self-excited power converters, and DC voltage common common terminals of the n voltage-type self-excited power converters and the n power diode rectifiers, respectively. A power converter comprising a DC smoothing capacitor connected via a reactor and connected to a load device in parallel. The n voltage-type self-excited power converters operate with a constant pulse pattern, and control the AC input current by adjusting the phase angle with respect to the voltage of the AC power supply to be applied to the DC smoothing capacitor. The power conversion device according to claim 14, wherein the power conversion device is controlled. The n voltage-type self-excited power converters operate in a one-pulse mode synchronized with the frequency of the AC power source, and control the AC input current by adjusting the phase angle with respect to the voltage of the AC power source to control the DC current. The power converter according to claim 14, wherein a voltage applied to the smoothing capacitor is controlled. The power converter according to any one of claims 8 to 16, wherein a reset circuit for resetting a current flowing through each of the recovery current suppressing reactors is connected in parallel. When the voltage of the AC power supply fluctuates, the n voltage-type self-excited power converters control by changing the command value of the voltage applied to the DC smoothing capacitor in accordance with the change of the power supply voltage. The power converter according to claim 8, wherein the power converter is characterized in that In the n voltage-type self-excited power converters, the angular frequency of the AC power supply is ω, the power supply voltage is Vs, the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k. The voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² + (ω · Ls · Is) ² }
It controls so that it may become. The power converter device of any one of Claims 8-18 characterized by the above-mentioned. In the n voltage-type self-excited power converters, the angular frequency of the AC power supply is ω, the power supply voltage is Vs, the input current is Is, the inductance value of the AC reactor is Ls, and the proportionality constant is k. The voltage Vd applied to the DC smoothing capacitor is
Vd = k · √ {Vs ² − (ω · Ls · Is) ² }
It controls so that it may become. The power converter device of any one of Claims 8-18 characterized by the above-mentioned.

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