JP2001045799A - Inverter-type engine generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a supply voltage to a load from decreasing by performing control so that the target value of an inverter input voltage being inputted to an inverter decreases within a certain range due to the increase in a detected load current. SOLUTION: The engine generator inputs a load current being outputted from an inverter 4 via a filter 5 and a DC voltage being outputted from a rectification circuit 3 to a control device 6, and detects a load current from the inverter 4 by a control device 6 for calculating a target reference voltage value. Then, control is made so that a DC voltage being outputted from the rectification circuit 3, namely the target value of an inverter input voltage being inputted to the inverter 4 decreases as the load current increases, thus preventing the load current from exceeding a prescribed range when the load current is large, and preventing the load current from becoming lower than the prescribed range when the load current is small and hence enabling an inverter input voltage to be within the prescribed range even if the load rapidly increases or decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an engine generator with an inverter.

[0002]

2. Description of the Related Art Conventionally, in an engine generator, the number of poles of the generator and the engine speed are limited in order to output AC power having a predetermined frequency. For example, 2
In order to output 60 Hz alternating current with the pole machine, the engine speed must be maintained at 3600 revolutions per minute irrespective of the connected load, so that the operation efficiency was poor. Also,
When it is desired to increase the output of the generator, the number of poles is limited, so that the generator device tends to be larger and heavier.

[0003] In order to solve such a problem, an inverter-type engine generator in which an AC output is once converted to DC by a rectifier circuit, and the converted DC power is converted into AC power of a target frequency and voltage by an inverter. Structured ones are being used. In such an inverter-type engine generator, the final output voltage / frequency does not depend on the frequency of the generator output voltage. Therefore, since the engine speed can be changed according to the magnitude of the load connected to the output stage of the inverter, it is possible to always control the operating state to be efficient. Also,
Since it is no longer dependent on the number of poles of the generator, for example, a permanent magnet rotating field type structure configured to perform a field with a large number of small permanent magnets built in a flywheel and extract electric power with a large number of stator windings By using the pole synchronous generator, the generator device can be configured to be lightweight and compact.

[0004]

As described above, in an engine generator using an inverter circuit, in order to stabilize the operation of the inverter circuit, an electrolytic capacitor for direct current smoothing is provided at a stage preceding the inverter circuit. Here, when the input voltage to the inverter circuit suddenly increases due to a sudden decrease in load such as load shedding, and exceeds the withstand voltage of the smoothing capacitor, the smoothing capacitor is damaged and the operation of the inverter circuit becomes unstable. . As one of means for solving such a problem, it is conceivable to use a high withstand voltage type as the smoothing capacitor, but the cost increases. Conversely, when the input voltage to the inverter circuit suddenly decreases due to a sudden increase in load such as when a load is applied, and falls below the minimum specified value, the inverter output voltage, that is, the supply voltage to the load becomes insufficient, and the AC output waveform becomes distorted. The problem that occurs.

Therefore, the engine generator according to the present invention uses the smoothing capacitor having the lowest withstand voltage as much as possible while keeping the input voltage to the inverter circuit within the specified range, and using the smoothing capacitor with the lowest withstand voltage as much as possible. This prevents the smoothing capacitor from being damaged due to fluctuations in the input voltage and prevents the inverter output voltage, that is, the supply voltage to the load, from becoming insufficient. As a technique for keeping the inverter input voltage constant, for example, a technique is known in which a rectifier circuit is configured as a thyristor circuit and the conduction angle of the thyristor is controlled.

[0006]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. That is, according to the present invention, in the engine generator configured to rectify the output of the AC generator driven by the engine and output the rectified output to the outside as an AC output of a predetermined frequency via an inverter, The load current of the engine generator was detected, and control was performed so that the target value of the inverter input voltage input to the inverter decreased within a certain range as the detected load current increased.

According to a second aspect of the present invention, the control target for controlling the inverter input voltage is an engine speed.

According to a third aspect of the present invention, the control target for controlling the input voltage of the inverter is a fuel supply amount, and an appropriate fuel supply amount is calculated from the magnitude of the load, so that the input voltage is fed forward. Control.

According to a fourth aspect of the present invention, the rectifier circuit for generating the inverter input voltage is constituted by a thyristor circuit, and the control of the inverter input voltage is performed by controlling the thyristor conduction angle.

According to a fifth aspect of the present invention, an engine generator configured to rectify the output of an AC generator driven by the engine and output the rectified output to the outside as an AC output of a predetermined frequency via an inverter. In the case, a first resistor is provided between the generator and the rectifier circuit, a second resistor is provided between the rectifier circuit and the inverter, and the inverter input voltage is detected. Only a circuit for conducting to the first resistor or the second resistor was provided.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. 1 is a circuit diagram showing a configuration of an engine generator with an inverter of the present invention, FIG. 2 is a diagram showing a change in inverter input voltage when a load is applied, FIG. 3 is a diagram showing a change in inverter input voltage when a load is cut off,
FIG. 4 is a circuit diagram showing an engine generator configured to control the inverter input voltage by engine control.
FIG. 6 is a diagram showing a control flow of the inverter input voltage of the engine generator in FIG. 4, FIG. 6 is a diagram showing a relationship between load current and DC voltage at each engine speed, and FIG. 7 is a relationship between load current and reference DC voltage. FIG. 8 is a circuit diagram showing an engine generator configured to control the inverter input voltage by engine control with the control target being the engine speed, and FIG. 9 is an inverter input voltage of the engine generator in FIG. FIG. 10 is a diagram showing the relationship between the load current and the engine speed, and FIG. 11 is a diagram showing the fuel supply amount as the control target and controlling the inverter input voltage by performing the engine control in feedforward. FIG. 12 is a circuit diagram showing an engine generator configured as described above, FIG. 12 is a diagram showing a control flow of an inverter input voltage of the engine generator in FIG. 11, and FIG. FIG. 14 is a diagram showing a relationship between a load current and a DC supply voltage in a fuel supply amount, FIG. 14 is a diagram showing a relationship between a load current and a fuel supply amount, and FIG. 15 is a thyristor circuit configured as a rectifier circuit, which controls the thyristor circuit. FIG. 16 is a circuit diagram showing an engine generator configured to control the inverter input voltage by means of the inverter, FIG. 16 is a diagram showing a control flow of the inverter input voltage of the engine generator in FIG. 15, and FIG. FIG. 18 is a circuit diagram showing an engine generator configured to control the inverter input voltage by applying pressure to the inverter generator. FIG. 18 is a diagram showing a control flow of the inverter input voltage of the engine generator shown in FIG.

First, the configuration of the engine generator with an inverter will be described. As shown in FIG. 1, AC power output from a power generator 2 driven by an engine 1 is
The rectifier circuit 3 converts the rectified DC output to DC, converts the rectified DC output to AC again by the inverter 4, and outputs the AC output to the outside through the filter 5. An electrolytic capacitor 11 for DC smoothing is interposed between the rectifier circuit 3 and the inverter 4.

Here, in order to supply stable AC power to the outside, the voltage of the DC output from the rectifier circuit 3 does not become higher than the withstand voltage of the DC smoothing electrolytic capacitor 11 and the desired AC output voltage Of the DC voltage (hereinafter referred to as DC voltage) is defined as a specified range R.

In the engine generator constructed as shown in FIG. 1, for example, as shown in FIG. 2, the load suddenly increases due to the load application, and the input voltage to the inverter 4 decreases.
If the voltage falls below the specified range R, the supply voltage to the load output from the inverter 4 will be insufficient, and the output waveform will be distorted.

As shown in FIG. 3, for example, the load suddenly decreases due to the load interruption, the input voltage to the inverter 4 rises, and becomes larger than the specified range R, so that the withstand voltage of the DC smoothing electrolytic capacitor 11 is reduced. If it exceeds, the DC smoothing electrolytic capacitor 11 is damaged, and the operation of the inverter 4 becomes unstable.

Therefore, in the present invention, the following control is performed so that the output voltage from the rectifier circuit 3 falls within the specified range R. That is, in the engine generator shown in FIG. 4, the load current output from the inverter 4 via the filter 5 and the DC voltage output from the rectifier circuit 3 are input to the control device 6. Then, as shown in FIG. 5, the control device 6 detects the load current from the inverter 4 (Step S101, Step S10).
2) Then, a target reference DC voltage value is calculated (step S103). The DC output from the rectifier circuit 3
The voltage is detected as an actual voltage, and the calculated reference DC voltage value is compared with the actual voltage value to calculate a deviation between the two (step S104). Based on this deviation, the drive amount of the actuator 8 that operates the fuel supply device 7 of the engine 1 is calculated and input to the actuator 8 (step S10).
5, Step S106). The fuel supply device 7 is operated by an actuator 8 to adjust the amount of fuel supply to the engine 1, and the rotation speed of the engine 1 is changed so that the DC voltage from the rectifier circuit 3 becomes the reference DC voltage value. Note that the current output from the rectifier circuit 3 may be used as the load current detected in steps S101 and S102.

FIG. 6 shows the engine speeds 12a and 12a.
9 shows the relationship between the load current and the DC voltage at b, 12c, 12d and 12e, and shows the engine speeds 12a and 12b
・ 12c ・ 12d ・ 12e Among the engine speed 12
a is the largest, the engine speed 12b, the engine speed 12c, the engine speed 12d, the engine speed 12
It becomes smaller in the order of e.

As described above, when the reference DC voltage value is calculated based on the load current and the engine speed is adjusted, when the load current is large, the DC voltage value output from the rectifier circuit 3 is used. Actuator 8 such that the engine speed is located at the lower limit side within the specified range R.
Of the rectifier circuit 3 when the load current is small.
The drive of the actuator 8 is controlled such that the DC voltage value output from the engine reaches an engine speed such that the DC voltage value is located on the upper limit side within the specified range R. For example, in the example shown in FIG. 6, when the load current Ia is the engine speed 12a, and when it is the load current Ib, the load current Ic is the engine speed 12b.
When the load current is large, the output DC voltage is located on the lower limit side within the specified range R, as indicated by the load-DC voltage line 13. As the load current decreases, the output DC voltage moves to the upper limit side within the specified range R.

As described above, when the load current is large, the output DC voltage is positioned on the lower limit of the specified range R, and when the load current is small, the output DC voltage is positioned on the upper limit of the specified range R. When the control device 6 calculates the reference DC voltage, as shown in FIG. 7, the reference DC voltage increases as the load current decreases within the above-described certain range, and the reference DC voltage decreases as the load current increases. Is set as follows.

As described above, by controlling the DC voltage output from the rectifier circuit 3, that is, the target value of the inverter input voltage input to the inverter 4, to decrease as the load current increases, When the load current is large, the reference DC voltage is positioned on the lower limit side within the specified range R in which the power can be stably supplied to the outside, and it is assumed that the load suddenly decreases and the inverter input voltage increases. So that the inverter input voltage does not exceed the specified range R.
A large overshoot margin can be secured. On the other hand, when the load current is small, the reference DC voltage is positioned on the upper limit side within the specified range R, and even if the load increases rapidly and the inverter input voltage decreases, the inverter input voltage is reduced to the specified range R. , It is possible to secure a large drop-down margin. As a result, even when the load suddenly increases or decreases, the inverter input voltage can be kept within the specified range R.

Further, such control can be performed by calculating a reference engine speed based on the detected load current, and controlling the engine speed based on the calculated reference engine speed. That is, in the engine generator shown in FIG. 8, the load current flowing from the inverter 4 to the load via the filter 5 and the engine speed of the engine 1 are input to the control device 6. And, as shown in FIG.
The control device 6 detects the load current from the inverter 4 (step S201, step S202), and calculates a reference engine speed which is a target engine speed (step S203). Further, the engine speed of the engine 1 is detected as the actual speed, and the calculated reference speed value and the actual speed value are compared and calculated to obtain a deviation between them (step S204). Based on this deviation, the driving amount of the actuator 8 that operates the fuel supply device 7 of the engine 1 is calculated and input to the actuator 8 (step S20).
5, step S206). The fuel supply device 7 is operated by an actuator 8 to measure the amount of fuel supplied to the engine 1, and is changed so that the engine speed becomes a reference speed value. Note that the current output from the rectifier circuit 3 may be used as the load current detected in steps S201 and S202.

When the reference rotational speed is calculated based on the load current and the engine speed is adjusted, when the load current is large, the DC voltage output from the rectifier circuit 3 is increased in the same manner as described above. The drive of the actuator 8 is controlled so that the value is at the lower engine speed within the specified range R. When the load current is small, the DC voltage value output from the rectifier circuit 3 is controlled to the specified range. The drive of the actuator 8 is controlled so that the engine speed becomes the upper limit side in R.

Here, in the conventional engine generator, as shown in a load-DC voltage line 14 shown in FIG.
Since the C voltage was always constant, the drop-down margin when the load current was small and the overshoot margin when the load current was large were small. In this case, the relationship between the load current and the engine speed is such that the engine speed increases as the load current increases, as shown by the engine speed curve 17 in FIG.

In the case of this example, when the load current is large, the output DC voltage is positioned at the lower limit of the specified range R. When the load current is small, the output DC voltage is set at the upper limit of the specified range R. As shown in the relationship between the load current and the engine speed shown in FIG. 10, the engine speed is increased as the load current is increased. Compared to the value of the rotation speed curve 17, the engine rotation speed curve 1 of this example
6 is set to be small, and when the load current is large, compared to the value of the conventional engine speed curve 17,
The value of the engine speed curve 16 of this example is set to be large. That is, in a region where the load current is small, the operation is performed at a high speed in advance to secure a large drop-down margin, and even if the load rapidly increases and the inverter input voltage decreases, the inverter input voltage falls below the specified range R. In the region where the load current is large, operation is performed at the required minimum rotation speed to secure a large overshoot margin, and even if the load suddenly decreases and the inverter input voltage increases, the inverter input voltage exceeds the specified range R. Is preventing that. As a result, even when the load suddenly increases or decreases, the inverter input voltage can be kept within the specified range R.

Further, the inverter input voltage can be controlled by the following configuration. That is, in the engine generator shown in FIG. 11, the load current output from the inverter 4 is input to the control device 6. And FIG.
As shown in (1), the control device 6 detects the load current from the inverter 4 (step S301, step S302).
An actuator 8 for controlling the fuel supply amount of the fuel supply device 7 by calculating in the control device 6
Is calculated (step S303), and the calculated value is input to the actuator 8 (step 304). Then, the fuel supply device 7 is operated by the actuator 8, the fuel supply amount to the engine 1 is measured, and the engine speed is changed. Step S301 and step S301
The current output from the rectifier circuit 3 may be used as the load current detected at 302.

As described above, when the fuel supply amount is calculated based on the load current and the fuel supply amount is adjusted, when the load current is large, the DC voltage value output from the rectifier circuit 3 is adjusted to the specified value. The drive of the actuator 8 is controlled so that the fuel supply amount is positioned on the lower limit side of the range R. When the load current is small, the DC voltage value output from the rectifier circuit 3 becomes the upper limit within the specified range R. The drive of the actuator 8 is controlled so that the fuel supply amount is located on the side. For example, in the example shown in FIG. 13, when the load current is Ia, the fuel supply amount is 22a, and when the load current is Ib, the fuel supply amount is 22b. Has a fuel supply of 22
When the load current is large, as shown by the load-DC voltage line 25, the output DC voltage is located on the lower limit side within the specified range R, and the output becomes smaller as the load current becomes smaller. The DC voltage is moved to the upper limit side within the specified range R.

Here, in the conventional engine generator, the reference DC voltage is always constant, as in the load-DC voltage line 26 shown in FIG. 13, so that the drop-down margin when the load current is small and the load The overshoot margin when the current was large was small. In this case, the relationship between the load current and the fuel supply amount is such that the engine speed increases as the load current increases, as shown by the fuel supply amount line 24 in FIG.

In the case of this example, when the load current is large, the output DC voltage is positioned at the lower limit of the specified range R. When the load current is small, the output DC voltage is set at the upper limit of the specified range R. 14, the fuel supply amount increases as the load current increases, as in the relationship between the load current and the fuel supply amount shown in FIG. The value of the fuel supply amount line 23 of this example is set to be smaller than the value of the supply amount line 24, and when the load current is large, the value of the fuel supply amount line 23 is smaller than the value of the conventional fuel supply amount line 24. The value of the fuel supply amount line 23 in the example is set to be large. That is, in a region where the load current is small, the fuel supply amount is increased in advance to secure a large drop-down margin, and even if the load suddenly increases and the inverter input voltage decreases, the inverter input voltage falls below the specified range R. In the region where the load current is large, the fuel supply amount is adjusted to the required minimum amount to secure a large overshoot margin, and even if the load suddenly decreases and the inverter input voltage increases, the inverter input voltage is regulated. The range R is prevented from being exceeded. As a result, even when the load suddenly increases or decreases, the inverter input voltage can be kept within the specified range R.

Here, when the load is cut off or the load is turned on, the load current changes abruptly, and the DC voltage output from the rectifier circuit fluctuates abruptly, and this fluctuation of the DC voltage is suppressed. Therefore, as described above, if only the control of the engine 1 is performed, for example, by controlling the engine speed by adjusting the fuel supply amount of the fuel supply device 7 by the actuator 8, a response delay to the control occurs. That is, in the case of such an engine control, the processing speed of the mechanical operation of the actuator 8, the processing speed of the chemical reaction of combustion in the engine 1, the processing speed of the mechanical operation of the engine 1 itself, and the like. There is an element related to delay. On the other hand, for example, if a thyristor circuit is used as the rectifier circuit 3 and the thyristor circuit is controlled to suppress the fluctuation of the DC voltage, only electrical processing in the semiconductor circuit is performed in the thyristor circuit. Therefore, no response delay occurs, and the fluctuation of the DC voltage can be suppressed more quickly.

Next, a description will be given of an example in which a thyristor circuit is used as the rectifier circuit 3, the thyristor circuit is controlled to suppress the fluctuation of the DC voltage, and the inverter input circuit is controlled. That is, in the engine generator shown in FIG.
A rectifier circuit for converting an AC output from the power generator into a DC is configured in the thyristor bridge 31, and the load current output from the inverter 4 and the DC voltage output from the thyristor bridge 31 are input to the control device 6. I have.
Then, as shown in FIG. 16, the control device 6 detects the load current from the inverter 4 (Step S401, Step S402), and calculates a target reference DC voltage value (Step S403). Further, the DC voltage output from the thyristor bridge 31 is detected as an actual voltage, and the calculated reference DC voltage value is compared with the actual voltage value to calculate the deviation between them (step S404). The conduction angle of the thyristor bridge 31 is calculated based on the deviation (step S405), and a gate signal corresponding to the determined conduction angle is output from the gate signal generating means 32 (step S4).
06), the conduction angle of the thyristor bridge 31 is controlled (step S407). Note that the current output from the rectifier circuit 3 may be used as the load current detected in steps S401 and S402.

When the reference DC voltage value is calculated based on the load current and the conduction angle of the thyristor bridge 31 is controlled, when the load current is large, the DC voltage value output from the rectifier circuit 3 is equal to the aforementioned DC voltage value. Control is performed such that the conduction angle is positioned on the lower limit side within the specified range R, and when the load current is small, the DC voltage value output from the rectifier circuit 3 is positioned on the upper limit side within the specified range R. It is controlled so that the conduction angle becomes large.

As described above, when the load current is large, the output DC voltage is positioned on the lower limit side within the prescribed range R to secure a large overshoot margin, and when the load current is small, the output DC voltage is reduced to the prescribed range R. In order to secure a large drop-down margin by being positioned on the upper limit side of the above, when calculating the reference DC voltage in the control device 6, as in the case of the above-described first embodiment, as shown in FIG.
The reference DC voltage is set to be higher as the load current is smaller, and the reference DC voltage is set lower as the load current is larger. Thus, even when the load suddenly increases or decreases, the inverter input voltage is kept within the specified range R. To be able to fit in.

As described above, the D input to the inverter 4
By controlling the conduction angle of the thyristor bridge 31 by using a thyristor bridge 31 in the rectifier circuit in order to suppress the fluctuation of the C voltage, the responsiveness is improved as compared with the case where engine control is performed, and quick control is performed. Can be performed. Thereby, the responsiveness of the entire inverter-type engine generator can be improved.

The following control can be performed to suppress a rapid change in the inverter input voltage. That is, in the engine generator shown in FIG. 17, the DC voltage output from the rectifier circuit is input to the DC voltage detection circuit 36 of the control device 6. Further, a resistor Ra is connected as a first resistor to a circuit between the power generator 2 and the rectifier circuit 3, and a switching means Sa is interposed in a circuit between the resistor Ra and the circuit. In a steady state, the circuit and the resistor Ra are separated by the switching means Sa. Further, a resistor Rb is connected as a second resistor to a circuit between the rectifier circuit 3 and the inverter 4, and a switching means Sb is interposed between the resistor Rb and the circuit. In a steady state, the circuit and the resistor Rb are connected by the switching means Sb.
And are divided.

When the DC voltage detecting circuit 36 detects a rapid rise in the DC voltage due to the interruption of the load or the like, the switching means Sa is turned on to connect the resistor Ra, or the switching means Sb is turned on. A resistor Rb is connected to the inverter to divide the increased voltage by the resistor Ra or the resistor Rb, thereby suppressing a change in a DC voltage (inverter input voltage) output from the rectifier circuit 3 and an inverter. It is configured to control the input voltage. That is, as shown in FIG.
It is determined whether the detected DC voltage is higher than a certain threshold (step S901), and if it is higher than the threshold, a drive signal for turning on the resistor Ra or the resistor Rb is generated (step S902). ). As a result, the excess voltage is divided by the conductive resistor Ra or the resistor Rb, and the inverter input voltage is suppressed. Then, in step S903, it is determined whether the DC voltage is within a certain reference range. If the DC voltage output from the rectifier circuit 3 is not within the reference range, the resistor Ra is output.
Alternatively, a drive signal for the resistor Rb is continuously generated, and if the drive signal is within the range, the drive signal is stopped (step S904), and the process ends.

As described above, the resistor Ra is provided between the generator 2 and the rectifier circuit 3, the resistor Rb is provided between the rectifier circuit 3 and the inverter 4, and the DC voltage (inverter) output from the rectifier circuit is provided. Input voltage) and only when the detected DC voltage rises sharply, the resistor Ra or the resistor Rb
With this configuration, the input voltage to the inverter circuit between the rectifier circuit 3 and the inverter 4 can be rapidly increased and the DC smoothing can be suppressed. The electrolytic capacitor 11 for use can be prevented from being damaged.

[0037]

As described above, the present invention has the following advantages. That is, as in claim 1,
Since the load current of the engine generator is detected and the target value of the inverter input voltage input to the inverter is controlled to decrease within a certain range as the detected load current increases, the load current is large. In such a case, even if the load suddenly decreases and the inverter input voltage increases, the inverter input voltage does not exceed a specified range in which the engine generator can stably supply power to the outside.
A large overshoot margin can be secured. Conversely, when the load current is small, it is possible to secure a large drop-down margin so that the inverter input voltage does not fall below the specified range even if the load suddenly increases and the inverter input voltage decreases. Become. This makes it possible to keep the inverter input voltage within the specified range even when the load suddenly increases or decreases.

Furthermore, since the control target for controlling the inverter input voltage is the engine speed, in a region where the load current is small, the engine is previously operated at a high speed and the drop-down margin is controlled. To ensure that the inverter input voltage does not fall below the specified range R even if the load suddenly increases and the inverter input voltage decreases. As a result, a large overshoot margin can be ensured, and even if the load suddenly decreases and the inverter input voltage increases, the inverter input voltage can be prevented from exceeding the specified range R. This allows
Even when the load suddenly increases or decreases, the input voltage of the inverter can be kept within the specified range.

Further, since the control target for controlling the inverter input voltage is the fuel injection amount, in a region where the load current is small, the fuel supply amount is increased in advance to reduce the drop-down margin. Even if the load suddenly increases and the inverter input voltage decreases, it is possible to prevent the inverter input voltage from falling below the specified range R. In a region where the load current is large, the fuel supply amount is reduced to a necessary minimum amount. To ensure a large overshoot margin, and even if the load suddenly decreases and the inverter input voltage increases, the inverter input voltage remains within the specified range R
Can be prevented. This makes it possible to keep the inverter input voltage within the specified range even when the load suddenly increases or decreases.

Further, the rectifier circuit for generating the inverter input voltage is constituted by a thyristor circuit, and the control of the inverter input voltage is performed by controlling the thyristor conduction angle. Responsibility is improved and quick control can be performed as compared with the case where engine control for controlling the number of revolutions, the fuel injection amount, and the like is performed. Thereby, the responsiveness of the entire inverter-type engine generator can be improved.

Further, a first resistor is provided between the generator and the rectifier circuit, a second resistor is provided between the rectifier circuit and the inverter, and the inverter input voltage is detected. Only when the input voltage rises sharply,
A circuit that conducts to the first resistor or the second resistor is provided, so that a rapid rise in the inverter input voltage can be suppressed quickly, and the input voltage to the inverter circuit between the rectifier circuit and the inverter rises sharply. Thus, it is possible to prevent the smoothing capacitor provided in the inverter circuit from being damaged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an engine generator with an inverter according to the present invention.

FIG. 2 is a diagram illustrating a change in an inverter input voltage when a load is applied.

FIG. 3 is a diagram showing a change in an inverter input voltage at the time of load interruption.

FIG. 4 is a circuit diagram showing an engine generator configured to control an inverter input voltage by engine control.

5 is a diagram showing a control flow of an inverter input voltage of the engine generator in FIG.

FIG. 6 is a diagram showing a relationship between a load current and a DC voltage at each engine speed.

FIG. 7 is a diagram showing a relationship between a load current and a reference DC voltage.

FIG. 8 is a circuit diagram showing an engine generator configured to control an inverter input voltage by engine control in which a control target is an engine speed.

9 is a diagram showing a control flow of an inverter input voltage of the engine generator in FIG.

FIG. 10 is a diagram showing a relationship between load current and engine speed.

FIG. 11 is a circuit diagram showing an engine generator configured to control the inverter input voltage by controlling the fuel supply amount and performing engine control in a feedforward manner.

12 is a diagram showing a control flow of an inverter input voltage of the engine generator in FIG.

FIG. 13 is a diagram showing a relationship between a load current and a DC voltage at each fuel supply amount.

FIG. 14 is a diagram showing a relationship between a load current and a fuel supply amount.

FIG. 15 is a circuit diagram showing an engine generator in which a rectifier circuit is configured as a thyristor circuit, and the thyristor circuit is controlled to control an inverter input voltage.

16 is a diagram showing a control flow of the inverter input voltage of the engine generator in FIG.

FIG. 17 is a circuit diagram showing an engine generator configured to control an inverter input voltage by dividing a voltage excess by a resistor.

18 is a diagram showing a control flow of an inverter input voltage of the engine generator in FIG.

[Explanation of symbols]

Reference Signs List 1 engine 2 power generator 3 rectifier circuit 4 inverter 6 controller 7 fuel supply device 8 actuator 11 DC smoothing electrolytic capacitor 12a, 12b, 12c, 12d, 12e engine speed 13 load-DC voltage line 31 thyristor bridge R specified range Ra・ Rb resistor

Continued on the front page F term (reference) 5H590 AA21 AA24 CA07 CC02 CD01 CD03 EA01 EA05 EA07 EB02 EB07 EB21 EB23 EB29 FA01 FA08 FB05 FC15 FC21 FC22 GA02 GA04 GA09 GA10 GB05 GB07 HA02 HA04 HA11 JA02 JA19 JB15

Claims (5)

[Claims] 1. An engine generator configured to rectify the output of an AC generator driven by an engine and output the rectified output to the outside as an AC output of a predetermined frequency via an inverter. Wherein the target value of the inverter input voltage input to the inverter is controlled to decrease within a certain range as the detected load current increases. Machine. 2. The inverter-type engine generator according to claim 1, wherein a control target for controlling the inverter input voltage is an engine speed. 3. The inverter-type engine generator according to claim 1, wherein a control target for controlling the inverter input voltage is a fuel supply amount. 4. The rectifier circuit for generating the inverter input voltage is constituted by a thyristor circuit, and the control of the inverter input voltage is performed by controlling a thyristor conduction angle. Inverter type engine generator. 5. An engine generator configured to rectify the output of an AC generator driven by an engine and output the rectified output to the outside as an AC output of a predetermined frequency via an inverter. Provide a first resistor between the circuit, provide a second resistor between the rectifier circuit and the inverter, detect the inverter input voltage, only when the detected inverter input voltage suddenly increases, the first resistor or An inverter-type engine generator provided with a circuit for conducting to a second resistor.