JP4693214B2 - Inverter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device suitable for a portable AC power supply device and the like.
[0002]
[Problems to be solved by the invention]
Inverter devices are frequently used in portable AC power supply devices, AC motor drive devices, uninterruptible power supply devices, and the like. Among these, in a portable AC power supply device, a load may be driven by connecting a plurality of portable AC power supply devices in parallel. In this case, the operation is performed by synchronizing the output frequency of the portable AC power supply device. By the way, when the frequency of one of the portable AC power supply devices changes slightly due to a load change or when an output voltage difference occurs between the portable AC power supply devices, There is a possibility that current (cross current) flows into the portable AC power supply device and damages the circuit components of the portable AC power supply device. In this case, a cross current flows from the higher output frequency to the lower output frequency.
[0003]
Conventionally, as a measure to prevent the cross current between the portable AC power supply devices, the delay or advance of the phase of the output voltage / current is monitored, and the output frequency is adjusted based on this to suppress the cross current. There is something like that. An example of the configuration is shown in FIG. The portable AC power supply device 1 is composed of an engine-driven AC generator 2 and an inverter unit 3, and outputs a sinusoidal AC voltage from output terminals 3 a and 3 b of the inverter unit 3. The inverter unit 3 includes a rectifier circuit 4 that rectifies the three-phase AC voltage output from the AC generator 2, a smoothing capacitor 5, a single-phase full-bridge inverter circuit 6, a filter circuit 7, a control circuit 8, and a drive circuit. 9 or the like. The control circuit 8 is mainly composed of a microcomputer 10 (hereinafter referred to as a microcomputer 10) and a PWM circuit 11 that generates a drive signal. The inverter circuit 6 is connected to a load, and when a plurality of portable AC power supply devices are operated in parallel, the inverter circuit 6 is connected in parallel in the plurality of units.
[0004]
In this configuration, the control circuit 8 controls the generator 2 so that the engine maintains a predetermined number of revolutions, and at the predetermined frequency (50 Hz or 60 Hz) from the output terminals 3a and 3b, a predetermined voltage (for example, an effective value of 100 V). PWM control is performed so as to output a sine wave AC voltage having.
[0005]
The control circuit 8 also includes an output voltage detection circuit 12 that detects the output voltage of the inverter circuit 6, an output current detection circuit 13 that also detects the output current, and a phase difference between the output voltage and the output current detected thereby. And a phase difference detection circuit 14 that detects the output frequency, and controls to increase the output frequency when the output current is delayed from the output voltage, and to decrease the output frequency when the output current is advanced. This balances the output when two AC power supply units are operated in parallel. In this case, the power supply device of 50 Hz specification is adjusted between 49.90 Hz and 50.10 Hz.
[0006]
By the way, when detecting the above-described phase difference, the phase difference is detected by counting the time from the zero cross point of the output voltage (alternating current) to the zero cross point of the output current. However, when the detected waveform of the output current is a distorted waveform, the zero cross may occur twice or may occur at an unusual timing. For this reason, when parallel operation is performed, the output current balance between the devices may not be uniform.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inverter device in which the output current balance between the devices is always equal when parallel operation is performed.
[0008]
[Means for Solving the Problems]
  The invention of claim 1 is a DC power supply circuit;
  A plurality of inverter circuits connected in parallel, each having a switching element and switching the output of the DC power supply circuit based on a PWM signal to output a high-frequency voltage;
  A filter circuit that outputs the high-frequency voltage as a sinusoidal AC voltage;
  Active power detection means for detecting the active power of the AC output by accumulating the product of the output voltage instantaneous value of the inverter circuit and the output current instantaneous value at the same timing as the inverter circuit;
  Phase angle calculating means for calculating the phase angle between the output voltage and the output current of the inverter circuit from the active power detected by the active power detecting means;
  Phase detection means for detecting whether the calculated phase angle is a leading phase or a lagging phase;
  When the active power detected by the active power detection means is positive, the output voltage according to the magnitude of the calculated phase angle when the output current of the inverter circuit is in a leading phase with respect to the output voltage. When the output current of the inverter circuit is in a delayed phase with respect to the output voltage, the frequency of the output voltage is set to be increased in accordance with the calculated phase angle. The frequency of the output voltage is variably controlled so that the detection result of the active power is maximized, and when the active power is negative, the output voltage of the inverter circuit is controlled to be increased.Control means and
  It is comprised including.
[0009]
In the first aspect of the invention, since the frequency of the output voltage is variably controlled so as to maximize the active power, the voltage difference is a cross current generated by the frequency difference when the plurality of inverter devices are operated in parallel. (Reactive power) can be reduced directly, and the output current balance between devices can always be equalized.
[0010]
  Claim 2InventionDC power supply circuit,
  A plurality of inverter circuits connected in parallel, each having a switching element and switching the output of the DC power supply circuit based on a PWM signal to output a high-frequency voltage;
  A filter circuit that outputs the high-frequency voltage as a sinusoidal AC voltage;
  Active power detection means for detecting the active power of the AC output by accumulating the product of the output voltage instantaneous value of the inverter circuit and the output current instantaneous value at the same timing as the inverter circuit;
  Reactive power calculation means for calculating reactive power based on the detected active power;
  Reactive power phase detection means for detecting whether the calculated reactive power is a leading phase or a lagging phase;
  When the active power is positive, when the reactive power is in the leading phase, the frequency of the output voltage is lowered according to the magnitude of the reactive power, and the reactive power is in the delayed phase when the reactive power is in the delayed phase. By increasing the frequency of the output voltage according to the magnitude of the output voltage, the output frequency is variably controlled so that the detection result of the reactive power is minimized, and when the active power is negative active power, Control to increase the output voltage of the inverter circuitControl means and
  It is comprised including.
[0011]
In the second aspect of the invention, since the frequency of the output voltage is variably controlled so as to minimize the reactive power, the cross current can be directly reduced when a plurality of inverter devices are operated in parallel. Thus, the output current balance between the devices can be always equalized.
[0017]
  The invention of claim 3 is claimed in claim 1.Or 2The present invention is characterized in that the active power detection means detects the active power in a period of at least half a cycle of the output voltage.
  According to this, active power detection can be performed in a short time, and subsequent frequency control can be performed quickly.
[0021]
  NormallyA very large cross current is not generated. However, if a large amount of cross current is generated, the switching element of the inverter circuit may be damaged, so it is better to eliminate the cross current as soon as possible.However, in the invention of claim 1 described above,Since it is controlled to increase the output voltage by judging that the active power is negative when a large amount of cross current flows, without waiting to detect the phase angle and phase delay / advance It becomes possible to prevent a large amount of cross current from flowing in quickly. As a result, damage to the switching elements of the inverter circuit can be effectively prevented.
  Claim4In the invention of claim 1 or 2, the inverter circuitTimesA feature is that auxiliary control means is provided to increase the frequency of the output voltage when the circuit voltage increases.
  If cross current is flowing,TimesThe circuit voltage also rises. Claim4In this invarTimesSince the frequency of the output voltage is increased according to the circuit voltage, the output current balance between the devices can be equalized more quickly in the case of parallel operation.
[0022]
  Claim5The invention of claim 1 or 2 further comprises a peak limiter circuit for performing a peak limiter for preventing overcurrent on the PWM control signal for generating the PWM signal, and outputting the peak limiter circuit to the peak limiter circuit. It is characterized in that an integrating circuit for stabilization is provided.
  This claim5In this invention, it is possible to prevent overcurrent and to prevent the occurrence of an oscillation phenomenon.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a first embodiment in which the inverter device of the present invention is applied to a portable AC power supply device (claim 1,3Will be described with reference to FIGS. 1 to 10. FIG.
  First, FIG. 1 shows an electrical configuration of a portable AC power supply device 21 that generates an AC power supply of, for example, 100 V · 50 Hz or 60 Hz. The portable AC power supply device 21 includes a three-phase AC generator 22 driven by an engine (not shown) and a single-phase inverter unit 23 connected to the subsequent stage.
[0024]
The AC generator 22 includes a rotor and an armature (both not shown), and a stepping motor 24 for controlling the rotational speed of the engine by controlling the amount of fuel (gasoline) supplied to the engine. Yes. The armature is wound with Y-connected main windings 25u, 25v, 25w and an auxiliary winding 26. The main winding terminals 27u, 27v, 27w and the auxiliary winding terminals 28a, 28b are respectively The inverter unit 23 is connected to input terminals 29u, 29v, 29w and input terminals 30a, 30b.
[0025]
On the other hand, the inverter unit 23 is configured as follows. That is, the rectifier circuit 33 is connected between the input terminals 29u, 29v, 29w and the DC power supply lines 31, 32. A smoothing capacitor 34 is connected between the DC power supply lines 31 and 32, and an inverter circuit 37 and a filter circuit 38 are cascaded between the DC power supply lines 31 and 32 and the output terminals 35 and 36. . The rectifier circuit 33 corresponds to the DC power supply circuit in the present invention.
[0026]
The rectifier circuit 33 has a configuration in which thyristors 39 to 41 and diodes 42 to 44 are connected in the form of a so-called three-phase mixed bridge, and the inverter circuit 37 includes transistors 45 to 48 (corresponding to switching elements) and a reflux circuit. The diodes 49 to 52 are configured to be connected in a so-called full bridge form.
[0027]
The filter circuit 38 includes a reactor 55 interposed between the output terminal 53 of the inverter circuit 37 and the output terminal 35 of the inverter unit 23, and a capacitor 56 connected between the output terminals 35 and 36 of the inverter unit 23. It is configured. The output terminal 54 of the inverter circuit 37 is directly connected to the output terminal 36 of the inverter unit 23, and a current transformer 57 for detecting the output current is provided in the current path from the output terminal 54 to the filter circuit 38. It has been. The output terminals 35 and 36 of the inverter unit 23 are connected in parallel when a plurality of the AC power supply devices 21 are operated in parallel, that is, the inverter devices 37 are connected in parallel. .
[0028]
Further, the inverter unit 23 includes a control power circuit 58, a control circuit 59, and a drive circuit 60. Among these, the control power supply circuit 58 inputs an AC voltage induced in the auxiliary winding 26 via the input terminals 30a and 30b, and rectifies and smoothes the AC voltage to control the control circuit 59 to operate (for example, 5V, ± 15V). The AC voltage induced in the auxiliary winding 26 is also input to the control circuit 59 in order to detect the engine speed.
[0029]
The control circuit 59 includes a microcomputer 61 (hereinafter referred to as a microcomputer 61), a DC voltage detection circuit 62, an output voltage detection circuit 63, an output current detection circuit 64, and a PWM circuit 65. The microcomputer 61 has a configuration in which a CPU, a RAM, a ROM, an input / output port, an A / D converter, a timer circuit, an oscillation circuit, and a D / A converter are made into a one-chip IC, although not specifically illustrated. Yes.
[0030]
  The DC voltage detection circuit 62 isAs apparent from FIG. 1, the DC power supply circuit 33 and the inverter circuit 37 are connected.The DC voltage Vdc between the DC power supply lines 31 and 32 is detected, and the detected DC voltage is output to the microcomputer 61 as a DC voltage detection signal. In this case, the microcomputer 61 reads the DC voltage detection signal, turns off the thyristors 39 to 41 when the DC voltage Vdc exceeds 180V, and turns on when the voltage becomes 180V or less.
[0031]
The output voltage detection circuit 63 includes a voltage dividing circuit that divides the voltage between the output terminals 53 and 54 of the inverter circuit 37 and a filter for removing a carrier wave component from the divided rectangular wave voltage (both shown in FIG. The output voltage detection signal Vs is output to the microcomputer 61 and the PWM circuit 65.
[0032]
The output current detection circuit 64 converts the output current detected by the current transformer 57 into a predetermined voltage level, and outputs the output current detection signal Is to the microcomputer 61 and the PWM circuit 65 as an output current detection signal. It is configured.
The PWM circuit 65 executes PWM control and generates drive signals G1 to G4 for the transistors 45 to 48. The drive signals G1 to G4 are supplied to the bases of the transistors 45 to 48 through the drive circuit 60, respectively.
[0033]
In the microcomputer 61, the output frequency can be set to either 50 Hz or 60 Hz by a switch input from a switch input unit (not shown). For example, it is set when an AC power supply of 50 Hz (100 V) is to be generated. A sinusoidal reference signal Vsin, which is an AC reference voltage having the same frequency as the output frequency, is supplied to the PWM circuit 65. In the PWM circuit 65, the sine wave reference signal Vsin is input to the error amplifier circuit 66 shown in FIG. The error amplification circuit 66 is supplied with the output voltage detection signal Vs of the output voltage detection circuit 63 as another input. This error amplifying circuit 63 subtracts and amplifies and outputs the PWM control signal Vsin ', and is adjusted so that the output voltage detection signal Vs corresponds to the set voltage / frequency, that is, output voltage feedback. Control is to be made. Further, as will be described later, the sine wave reference signal Vsin is also used for calculating the output active power.
[0034]
In addition, the PWM circuit 65 is provided with a peak limiter circuit 67 as shown in FIG. 2 showing a part of the internal configuration thereof, and is configured to include an operational amplifier 68 and an integration circuit 69. The operational amplifier 68 is supplied with the output current detection signal Is of the output current detection circuit 64 and the peak current reference signal Ik. When the output current detection signal Is is equivalent to an overcurrent, the peak current reference signal Ik is It is turned on for the part that exceeds. The peak current reference signal Ik includes signal levels “+ Ik” and “−Ik” (see FIG. 3A) due to hysteresis. At this time, since the feedback is applied by the integrating circuit 69, the PWM control signal Vsin 'has a waveform in which the peak portion is cut almost flat as shown in FIG. If the integration circuit 69 is not provided, the circuit may oscillate because the PWM control signal Vsin 'of the peak limiter circuit 67 falls and rises instantaneously. In the present embodiment, this is not the case. Absent. When no overcurrent is generated, the PWM control signal Vsin 'has a sine wave waveform as shown by a broken line in FIG.
[0035]
As shown in FIG. 4A, the PWM circuit 65 uses the PWM control signal Vsin ′ and a carrier frequency signal Sc (for example, a waveform with an extremely reduced frequency for the sake of convenience) as a comparator 70. As a result, the drive signals G1 to G4 are generated so as to obtain the rectangular-wave-shaped high-frequency voltage Vo (100V · 50 Hz or 60 Hz as viewed in the figure) shown in FIG. The high-frequency voltage Vo generated in this way is removed of high-frequency components by the filter circuit 38, and as shown in FIG. 5C, for example, an AC output Voac of 100 V · 50 Hz or 60 Hz is formed. Note that the PWM control signal Vsin 'in FIG. 4C shows a state when there is no overcurrent.
[0036]
The microcomputer 61 functions as an active power detection unit, a phase angle detection unit, a phase detection unit, and a control unit. These functions will be described below together with operations.
When the operation is started, the microcomputer 61 controls the output frequency according to the control flowchart shown in FIG. That is, in step Q1, the first zero cross of one cycle of the output voltage Vo (see FIG. 6, timing t0) is detected. In this case, the microcomputer 61 ideally matches the effective zero crossing of the sine wave reference signal Vsin and the output voltage Vo. Therefore, at the beginning of one cycle of the sine wave reference signal Vsin (timing that changes to the plus side). The zero cross timing t0 is determined. In step Q2, it is detected whether the instantaneous current value Is (1) is positive or negative. That is, it is detected whether the current is a lead phase or a lag phase with respect to the voltage, thereby detecting whether a phase angle θ described later is a lead phase or a lag phase.
[0037]
Thereafter, the instantaneous value Is (n) (n is 1 to 6) is detected from the detected output current signal Is at the timing of 6 times (equally spaced in time) for 1/2 cycle (step Q3). In step Q4, an instantaneous active power P (n) is calculated. That is, the product of the instantaneous value Is (n) of current at each detection opportunity (1) to (6) in FIG. 6 and the sine wave reference signal Vsin (n) (which is known in advance) is obtained, and this Remember. In the next step Q5, the square of the instantaneous value I (n) is obtained and stored. When 6 times are completed (“YES” in step Q6), the process proceeds to step Q7, and the active power P is calculated (detected). In this case, the active power P is
P = P (1) +... P (6)
[0038]
Next, the process proceeds to step Q8, and the current effective value I is obtained. This current effective value I is
I = ((Is (1)²+ ... Is (6)²/ 6)^1/2  Is required.
In the next step Q9, the phase angle θ is obtained. That is, the relationship between the apparent power I × E and the active power P is
Since P = (I × E) cos θ (θ is a phase angle),
cos θ = P / (I × E), and the phase angle θ is determined from this cos θ.
[0039]
In this case, when positive is detected in step Q2, it is detected that the phase angle θ is a leading phase, and when negative is detected, it is detected that the phase angle θ is a delayed phase. Has been.
[0040]
In the next step Q10, the output frequency is set by this phase angle θ and its advance or delay phase. This setting is performed based on the data table shown in FIG. That is, when the phase angle θ is a leading phase, the frequency is set to decrease according to the magnitude of the phase angle θ, and when the phase angle θ is a delayed phase, the phase angle θ is set according to the magnitude of the phase angle θ. The frequency is set to increase. For example, when the phase angle θ is 0 ° and 50.0 Hz is set as a reference, when the phase angle θ is 90 degrees, the phase angle θ is set to 50.1 Hz, and the interval is set linearly.
[0041]
Furthermore, as described above, the microcomputer 61 has an output voltage control function that detects the DC voltage Vdc and adjusts the output voltage regardless of the on / off control of the thyristors 39 to 41. That is, as shown in step R1, step R2, and step R3 in the flowchart of FIG. 8, control is performed to increase the output voltage when Vdc is 180 V or higher. That is, control is performed so as to increase the output voltage by increasing the amplitude of the sine wave reference signal Vsin. For example, when the voltage is increased from 180V by 1V, the output frequency is controlled to be increased by 0.01Hz.
[0042]
The case where such a portable AC power generator 21 is connected in parallel to supply power to the load F will be described. In FIG. 9, for example, one of two portable AC power generators is a portable AC power generator 21A, and the other is a portable AC power generator 21B. Now, when the output frequency of one AC power generator 21A instantaneously becomes, for example, 49.96 Hz for some reason (for example, load fluctuation), a cross current flows from the other AC power generator 21B to one AC power generator 21A. Flowing. Also, as shown in FIG. 10, a cross current flows from the AC power generator 21B to the AC power generator 21A even when the output voltage of the AC power generator 21B is higher than the output voltage of the AC power generator 21A.
[0043]
In this case, in AC generator 21B, the phase of the current is delayed with respect to the voltage (the phase angle of the delayed phase is obtained). On the other hand, in the AC power generator 21A, the current advances with respect to the voltage (the phase angle of the advance phase).
In this embodiment, when the phase angle of the delayed phase is reached, the output frequency is controlled to increase, and when the phase angle of the advanced phase is reached, the output frequency is controlled to be lowered. Then, in AC generator 21A, the output frequency further decreases, and in AC generator 21B, the output frequency further increases. As a result, electric power is generated from the AC power generator 21B to the AC power generator 21A. As a result, the voltage Vdc, which is the main circuit voltage of the inverter circuit 37 of the AC power generator 21A, increases. Then, AC power generator 21A controls to increase the output voltage. As a result, the flow of the cross current into the AC power generator 21A is reduced, and as a result, the cross current between the power supply devices 21A and 21B is eliminated. In this way, control is performed so that the detection result of the active power is maximized.
[0044]
In this case, according to the present embodiment, the active power P including the phase angle θ element between the output voltage and the output current is detected, and the phase angle θ is calculated based on the detected active power P. Even when there is a waveform distortion in the output current or the detection signal Is of the output current detection circuit 64 serving as the output current detection means, the phase angle θ can be detected almost accurately. That is, the detection accuracy of the phase angle θ can be improved.
[0045]
Therefore, the frequency control of the output voltage can be appropriately performed based on the phase angle with high detection accuracy, and the output current balance between the devices is always equal when parallel operation is performed. It becomes.
[0046]
In particular, according to the present embodiment, since the active power is detected in the half cycle period of the AC voltage for detecting the active power, the active power can be detected in a short time, and the subsequent frequency control is performed. It can be done quickly. However, the active power may be detected in one cycle of AC voltage.
[0047]
  11 and 12 show a second embodiment of the present invention (claims).2In this embodiment, the output frequency is set according to the magnitude of the reactive power and the leading phase / lagging phase of the reactive power. Different. That is, step S1 to step S8 in the flowchart of FIG. 11 are the same as step Q1 to step Q8 of FIG. In step S9, cos θ is obtained, and in step S10, sin θ is obtained from cos θ and reactive power is calculated (reactive power calculating means). Whether the reactive power is the leading phase or the lagging phase can be determined from the determination result in step S2 (reactive power phase detecting means). When the instantaneous value I (1) of the current is positive, it is a lead phase,NegativeSometimes it is a lagging phase.
[0048]
In step S11, the frequency is set from the magnitude and phase of the reactive power with reference to the data table of FIG. As an example, when the reactive power of the lead phase is −2800 W (this corresponds to −90 ° in terms of the phase angle θ), it corresponds to 49.9 Hz. In this embodiment, the same effect as that of the first embodiment can be obtained.
[0049]
  As a method of detecting reactive power, the third embodiment of the present invention is used.Examples andAs shown in FIG. 13, an AC voltage Vx having a waveform obtained by a 90 ° phase advance of the sine wave reference signal Vsin, which is a reference AC voltage, is set (the AC voltage that the microcomputer 61 has advanced by 90 ° from the sine wave reference signal Vsin). Vx is included as data), the product of Vx and the output current detection signal Is is obtained at the timing of six half cycles, and the reactive power is detected by summing the product for six times. In this way, reactive power can be obtained directly.
[0050]
  The fourth embodiment of the present inventionExampleThe following is described.
  That is, the portable AC power supply device 21 in the first embodiment or the second embodiment is suitable for solving this when a relatively small cross current flows into one device when operated in parallel. That is, when a relatively small cross current flows, as shown in FIG. 14 (a), the phase has a phase that does not exceed 90 °, although the delayed phase also has a leading phase, and the active power is Is positive. However, if the cross current is large, the switching element of the inverter circuit may be damaged on the device side where the cross current enters, so it is better to eliminate the cross current as soon as possible. In this case, as shown in FIG. 14B, the phase of the current with respect to the sine wave reference signal Vsin is shifted by 90 ° or more (becomes an opposite phase), and the active power is negative.
[0051]
Considering this point, in the fourth embodiment, active power detection means for detecting the active power of the AC output and control to increase the output voltage when the detected active power is negative active power. It is set as the structure provided with the control means to do. According to this, it becomes possible to prevent a large amount of cross current from flowing in quickly without waiting for detection of a phase angle or phase delay / advance. As a result, damage to the switching elements of the inverter circuit can be effectively prevented.
[0052]
  Furthermore, in the first embodiment or the second embodiment, the inverter circuit 37circuitAuxiliary control means may be provided so as to increase the frequency of the output voltage when the voltage Vdc between the DC power supply lines 31 and 32, which is a voltage, rises.4Invention). For example, if the voltage Vdc increases by 1 V, the output frequency may be increased by 0.01 Hz. Even in this case, in the case of parallel operation, the output current balance between the devices can be equalized more quickly.
[0053]
【The invention's effect】
  As apparent from the above description, the present invention can obtain the following effects.
  According to the invention of claim 1, since the frequency of the output voltage is variably controlled so as to maximize the active power, the output current balance between the devices is always equalized when a plurality of inverter devices are operated in parallel. CanThe
  According to the invention of claim 2, since the frequency of the output voltage is variably controlled so as to minimize the reactive power, the output current balance between the devices is always equalized when a plurality of inverter devices are operated in parallel. CanThe
[0055]
  Claim3According to the invention, since the active power detecting means detects the active power in the period of at least a half cycle of the output voltage, the active power can be detected in a short time, and the subsequent frequency control is performed. Can be done quicklyThe
[0058]
  Claim4According to the invention of InvarTimesSince the frequency of the output voltage is increased according to the circuit voltage, the output current balance between the devices can be equalized more rapidly in the case of parallel operation.
  Claim5According to the invention, overcurrent can be prevented and the occurrence of oscillation phenomenon can be prevented.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention.
FIG. 2 is a circuit diagram showing a part of a PWM circuit.
3 is a diagram showing each waveform in FIG. 2;
FIG. 4 is a waveform diagram showing waveforms related to PWM control.
FIG. 5 is a flowchart for explaining control contents;
FIG. 6 is a diagram showing a sine wave reference signal and an output current detection signal
FIG. 7 is a diagram showing frequency setting data.
FIG. 8 is a flowchart for explaining control contents different from FIG.
FIG. 9 is a diagram showing an operation example of two portable AC power generators in a state where a cross current related to the output frequency is generated.
FIG. 10 is a diagram showing an operation example of two portable AC power generators in a state where a cross current related to the output voltage is generated.
FIG. 11 is a flowchart for explaining control contents according to the second embodiment of the present invention.
FIG. 12 is a view corresponding to FIG.
FIG. 13 is a waveform diagram showing a third embodiment of the present invention.
FIG. 14 is a waveform diagram showing a fourth embodiment of the present invention.
15 is a view corresponding to FIG. 1 showing a conventional example.
[Explanation of symbols]
21 is a portable AC power supply device (inverter device), 22 is an AC generator, 23 is an inverter unit, 33 is a rectifier circuit (DC power supply circuit), 37 is an inverter circuit, 38 is a filter circuit, 59 is a control circuit, 61 Is a microcomputer (active power detection means, phase angle detection means, phase detection means and control means), 63 is an output voltage detection circuit (output voltage detection means), 64 is an output current detection circuit (output current detection means), and 67 is a peak. A limiter circuit 69 is an integrating circuit.

Claims (5)

A DC power supply circuit;
A plurality of inverter circuits connected in parallel, each having a switching element and switching the output of the DC power supply circuit based on a PWM signal to output a high-frequency voltage;
A filter circuit that outputs the high-frequency voltage as a sinusoidal AC voltage;
Active power detection means for detecting the active power of the AC output by accumulating the product of the output voltage instantaneous value of the inverter circuit and the output current instantaneous value at the same timing as the inverter circuit;
Phase angle calculating means for calculating the phase angle between the output voltage and the output current of the inverter circuit from the active power detected by the active power detecting means;
Phase detection means for detecting whether the calculated phase angle is a leading phase or a lagging phase;
When the active power detected by the active power detection means is positive, the output voltage according to the magnitude of the calculated phase angle when the output current of the inverter circuit is in a leading phase with respect to the output voltage. When the output current of the inverter circuit is in a delayed phase with respect to the output voltage, the frequency of the output voltage is set to be increased in accordance with the calculated phase angle. Control means for variably controlling the frequency of the output voltage so that the detection result of the active power is maximized, and for controlling the output voltage of the inverter circuit to be increased when the active power is negative. An inverter device. A DC power supply circuit;
A plurality of inverter circuits connected in parallel, each having a switching element and switching the output of the DC power supply circuit based on a PWM signal to output a high-frequency voltage;
A filter circuit that outputs the high-frequency voltage as a sinusoidal AC voltage;
Active power detection means for detecting the active power of the AC output by accumulating the product of the output voltage instantaneous value of the inverter circuit and the output current instantaneous value at the same timing as the inverter circuit;
Reactive power calculation means for calculating reactive power based on the detected active power;
Reactive power phase detection means for detecting whether the calculated reactive power is a leading phase or a lagging phase;
When the active power is positive, when the reactive power is in the leading phase, the frequency of the output voltage is lowered according to the magnitude of the reactive power, and the reactive power is in the delayed phase when the reactive power is in the delayed phase. By increasing the frequency of the output voltage according to the magnitude of the output voltage, the output frequency is variably controlled so that the detection result of the reactive power is minimized, and when the active power is negative active power, An inverter device comprising: control means for controlling the output voltage of the inverter circuit to increase . The inverter device according to claim 1 or 2 , wherein the active power detection means detects the active power in at least a half cycle period of the AC output voltage. The auxiliary control means is provided to increase the frequency of the output voltage when the DC voltage between the DC power supply lines connecting the DC power supply circuit and the inverter circuit rises. of the inverter device. A peak limiter circuit for performing a peak limiter for preventing overcurrent on a PWM control signal for generating a PWM signal is provided, and an integration circuit for stabilizing the output is provided in the peak limiter circuit. The inverter device according to claim 1 or 2 .

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