JP6564640B2 - Engine generator - Google Patents

Description

  The present invention relates to an engine generator equipped with power storage means that is driven by an engine and can assist electric power according to a load.

  In general, as a portable generator used outdoors, an engine generator is known that is equipped with a power storage unit that is driven by an engine and that can perform power assist according to a load (see Patent Document 1). For example, as shown in FIG. 7, an engine generator 100 described in Patent Document 1 includes an engine 101, a permanent magnet generator 102 that is driven by the engine 101 and outputs alternating current, and the permanent magnet generator. Rectifying means 103 for rectifying the alternating current output from the machine 102 and converting it into direct current; a step-up / step-down means (DC / DC step-up / down chopper) 104 for converting the direct current from the rectifying means 103 into a preset voltage; Electric storage means (EDLC) 105 charged with a part of the direct current from the step-up / step-down means 104, and DC / AC conversion means for converting the direct current from the step-up / step-down means 104 into alternating current of a preset frequency and outputting it. (Inverter) 106 and an engine for controlling increase / decrease in the number of revolutions of the engine 101 in accordance with the amount of power output from the DC / AC conversion means 106 to the load 108 And a control means (ECU) 107.

  In the engine generator 100, when the load 108 starts operation, the DC / AC conversion means 106 outputs to the load 108 as AC power having a preset voltage and frequency. The status of the electric power output from the DC / AC conversion means 106 and the status of the voltage of the power storage means 105 are transmitted to the engine control means 107, and the engine control means 107 adjusts the rotational speed of the engine 101 according to these conditions. .

  When the load 108 has a large inrush current at the start-up such as a motor, the power for operating the load 108 is higher than the power output from the permanent magnet generator 102 rotating at the engine speed at that time. May become temporarily larger. In the engine generator 100, since the power storage means 105 is charged before the load 108 starts operation, in such a case, the power storage means 105 starts discharging and corresponds to insufficient power. Electric power is taken out from the power storage means 105, and power obtained by adding the power from the power storage means 105 to the power from the permanent magnet generator 102 is supplied to the load 108 via the DC / AC conversion means 106.

  As described above, according to the engine generator 100, the rotational speed of the engine 101 can be automatically changed according to the state of the load 108 to save fuel and reduce noise, and start the motor and the like. It is possible to cope with a large inrush current at the start of the load such as when

JP 2011-256729 A

  However, the engine generator 100 of Patent Document 1 has the following problems. That is, generally, the control circuit of the step-up / step-down means (DC / DC step-up / step-down chopper) 104 that converts the direct current from the rectifying means 103 into a preset voltage can provide a stable output even if the load 108 fluctuates. A voltage feedback and current feedback circuit for performing such PID control is provided. In this configuration in which the power storage means 105 is a capacitor, a current feedback loop is provided inside the voltage feedback loop, and charging is performed while preventing an excessive current from flowing by providing a limiter for the current. In the case of the control configuration as described above, the response speed of the voltage feedback needs to be about 1/100 of the response speed of the current feedback. Response delay of voltage conversion is likely to occur.

  When dealing with a large inrush current at the time of starting a load such as when starting a motor or the like, the power output from the permanent magnet generator 102 is insufficient due to a delay in voltage conversion response in the step-up / step-down means 104. A lot of electric power is taken out from the charged power storage means 105. As a result, in order to cope with such a temporary increase in the power supplied to the load, the power storage capacity of the power storage means 105 must be increased, and the power storage means 105 is unnecessarily large and increases costs. was there.

  The present invention has been made to solve such a problem, and in an engine generator capable of assisting power by the power storage means, the power supply from the power storage means can be reduced against a temporary increase in power supplied to the load. Another object of the present invention is to provide an engine generator capable of reducing the size of the power storage means.

In order to achieve the above object, an engine generator according to the present invention has the following configuration.
(1) An engine, an alternator driven by the engine and outputting alternating current, a rectifying means for rectifying the alternating current output from the alternator and converting it into direct current, and a direct current output from the rectifying means are preset. DC / DC step-down means for converting the voltage into a voltage, power storage means charged by a part of the direct current output from the DC / DC step-down means, and direct current output from the DC / DC step-down means and the power storage means. An inverter that converts the alternating current into a preset frequency and outputs it to the load, and controls the increase / decrease in the engine speed according to the amount of electric power output from the inverter to the load, and the DC / DC step-down means An engine generator comprising a control device for controlling,
When the load increases , the control device includes the DC / DC step-down means if the output voltage, output current and output power of the step-down chopper in the DC / DC step-down means are within predetermined limits. When the output from the step-down chopper is increased to 100% duty ratio and the load is decreased , the output voltage, output current, or output power of the step-down chopper in the DC / DC step-down means is If a predetermined limit value is exceeded, a command circuit is provided for decreasing the output current by setting the output from the step-down chopper in the DC / DC step-down means to a duty ratio of 0%.

In the present invention, if the output voltage, output current, and output power of the step-down chopper in the DC / DC step-down means are within predetermined limit values, the control device outputs from the step-down chopper in the DC / DC step-down means. If the output voltage is increased at a duty ratio of 100%, and the output voltage, output current, or output power of the step-down chopper in the DC / DC step-down means exceeds a predetermined limit value, the step-down in the DC / DC step-down means Since a command circuit for decreasing the output voltage output from the chopper with a duty ratio of 0% is provided, the output change of the step-down chopper in the DC / DC step-down means is judged by a simple program, and the step-down chopper in the DC / DC step-down means is used. Can be ordered quickly. Therefore, the response speed of the voltage conversion in the DC / DC step-down means can be increased also in the case of dealing with a large inrush current at the time of starting such as a motor. Therefore, the power output from the alternator can be maximized in a short time, and the power extracted from the power storage means can be decreased. As a result, in order to cope with a temporary increase in power supplied to the load, the power storage capacity of the power storage means need not be increased.
Therefore, according to the present invention, in an engine generator capable of assisting power by the power storage means, engine power generation that can reduce the power supply from the power storage means and reduce the size of the power storage means against a temporary increase in power supplied to the load. Machine can be provided.

(2) In the engine generator described in (1),
The command circuit is provided with a hysteresis for determining the condition of the output current.

  In the present invention, since the command circuit is provided with hysteresis for determining the output current condition, it is possible to prevent the output current of the step-down chopper in the DC / DC step-down means from becoming excessive. Therefore, the constituent elements of the DC / DC step-down means can be made small in current rating, so that the DC / DC step-down means can be reduced in size and cost can be reduced.

  According to the present invention, an engine generator capable of assisting power by the power storage means can reduce the power supply from the power storage means and reduce the size of the power storage means against a temporary increase in power supplied to the load. Can be provided.

1 is an overall configuration diagram of an engine generator according to an embodiment of the present invention. It is a detailed block diagram of the DC / DC step-down means shown in FIG. FIG. 2 is a control flowchart of the command circuit shown in FIG. 1. FIG. 4 is a correlation diagram between current and voltage at a limit value shown in FIG. 3. The output current when no hysteresis is provided in the determination condition of the output current and the time lapse of the duty ratio. The output current when the hysteresis is provided in the output current determination condition and the time lapse of the duty ratio. 1 is an overall configuration diagram of an engine generator shown in Patent Document 1. FIG.

<Overall configuration of engine generator and its control method>
Next, the overall configuration and control method of the engine generator according to the embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 shows an overall configuration diagram of an engine generator according to an embodiment of the present invention. FIG. 2 shows a detailed block diagram of the DC / DC step-down means shown in FIG. FIG. 3 shows a control flow diagram of the command circuit shown in FIG. FIG. 4 shows a correlation diagram between current and voltage at the limit values shown in FIG. FIG. 5 shows the output current and the duty ratio over time when hysteresis is not provided in the output current determination condition. FIG. 6 shows the output current and the duty ratio over time when hysteresis is provided in the output current determination condition.

  As shown in FIGS. 1 and 2, the engine generator 10 according to this embodiment includes an engine 1, an alternator 2 that is driven by the engine 1 and outputs alternating current, and an alternating current output from the alternator 2 is rectified. Rectifying means 31 for converting to direct current, DC / DC step-down means 32 for converting the direct current output from the rectifying means 31 into a preset voltage, and direct current output from the DC / DC step-down means 32 The power storage means 4 charged by a part, the inverter 5 that converts the direct current output from the DC / DC step-down means 32 and the power storage means 4 into alternating current of a preset frequency and outputs the alternating current to the load 8, and the inverter 5 And a control device 6 for controlling the increase / decrease of the rotational speed of the engine 1 in accordance with the amount of electric power output to the load 8 and controlling the DC / DC step-down means 32. The power storage means 4 is a capacitor, and is preferably an EDLC (electric double layer capacitor). The rectifying unit 31 and the DC / DC step-down unit 32 constitute an AC / DC converter 3. When there is a margin in the output of the AC / DC converter 3, the power storage means 4 is charged.

  In addition, the control device 6 includes an engine control device (ECU) 62 that controls the rotational speed of the engine 1 and a detection circuit 71 that detects the amount of power output from the inverter 5 to the load 8. The control device 6 calculates a control signal for controlling the engine control device (ECU) 62 based on the detection signal of the detection circuit 71 and outputs the control signal to the engine control device (ECU) 62 through the circuit 72. The engine control unit (ECU) 62 controls the number of revolutions of the engine 1 according to the increase or decrease in the amount of electric power output to the load 8. Therefore, if the amount of electric power output to the load 8 decreases, the rotational speed of the engine 1 is decreased, and if the amount of electric power output to the load 8 increases, the rotational speed of the engine 1 is increased. The engine control unit (ECU) 62 maintains an idling state in which the engine 1 is rotated at a predetermined rotational speed when the load 8 is stopped.

  The engine 1 and the alternator 2 are mechanically connected, and the alternator 2 outputs a three-phase alternating current proportional to the engine speed. The three-phase AC output of the alternator 2 is supplied to the rectifying means 31 and converted into a DC output. Since the direct current voltage output from the rectifying means 31 changes in potential according to the engine speed, it is stepped down to a constant voltage by the DC / DC step-down means 32 and sent to the inverter 5.

  Further, the DC / DC step-down unit 32 includes a step-down chopper 321, and the step-down chopper 321 steps down the DC voltage output from the rectifying unit 31. At this time, the output voltage Vo is output by multiplying the voltage Vi input from the rectifier 31 to the step-down chopper 321 by a predetermined duty ratio α.

  In addition, the control device 6 includes a command circuit 61 that operates the DC / DC step-down means 32 in a control flow described below. The command circuit 61 is connected to the DC / DC step-down means 32 via the circuit 73, and as shown in FIG. 3, whether or not the output voltage, the output current, or the output power of the step-down chopper 321 is within a predetermined limit value. (Step: S1), and if the output voltage, output current, and output power of the step-down chopper 321 are within predetermined limits, the output voltage of the DC / DC step-down means 32 is increased at a duty ratio of 100%. (Step: S2) If the output voltage, output current, or output power of the step-down chopper 321 exceeds a predetermined limit value, the output voltage of the DC / DC step-down means 32 is decreased at a duty ratio of 0%. (Step: S3).

  Further, the limit value shown in step S1 of FIG. 3 has a correlation between current and voltage as shown in FIG. 4 so as not to exceed the maximum voltage limit value Vs, the maximum current limit value Is, and the maximum power limit value Ps. ing. That is, as shown in FIG. 4, the current limit value maintains a constant value (current maximum limit value Is) from zero to Ps / Is, and then decreases in inverse proportion to the increase in voltage. The maximum limit value Vs is Ps / Is.

  In addition, within the limit value shown in FIG. 4 (the shaded area), the duty ratio of the DC / DC step-down means 32 is 100%, and in the range exceeding the limit value shown in FIG. The duty ratio of the / DC step-down means 32 is 0%. Therefore, the voltage conversion of the DC / DC step-down unit 32 is determined as 1 or 0, and the response speed of the voltage conversion in the DC / DC step-down unit 32 can be increased. According to the experiments by the present inventors, the response speed of the voltage conversion can be increased about 10 times as compared with the conventional control method for obtaining the duty ratio by PID control. Therefore, even when the power supplied to the load 8 temporarily increases, such as when dealing with a large inrush current at the time of starting a motor or the like, the power output from the alternator 2 is increased in a short time. Thus, the electric power taken out from the power storage means 4 can be reduced as much as possible.

  Further, when the output voltage Vo of the step-down chopper 321 is low, such as when charging of the power storage means 4 is started, the output current jumps at the moment when the control device 6 outputs a duty ratio of 100%, as shown in FIG. Since the output current jumps at a high speed of several μs, there is a slight delay from when the output current exceeds the limit value (current maximum limit value Is) until the duty ratio becomes 0%. This delay increases the output current jump. Even when the duty ratio is 0%, the output current descending speed is slower than that at the time of rising, so that an average current higher than the limit value (current maximum limit value Is) is output.

  On the other hand, when the limit value of the output current is set to the upper limit value IsH having the same value as the above-described maximum current limit value Is and the lower limit value IsL having a value lower than the upper limit value IsH, FIG. As shown, by setting the limit value at the fall of the output current to the lower limit value IsL, the timing at which the duty ratio is 100% can be delayed, and the average current value can be lowered. In this way, the control device 6 sets the output current limit value to the upper limit value IsH having the same value as the maximum current limit value Is and the lower limit value IsL having a lower value, thereby allowing the program to be programmed. Since the hysteresis is provided in the output current determination condition above, it is possible to prevent the output current of the step-down chopper 321 in the DC / DC step-down means 32 from becoming excessively large. Thereby, since the current rating value of the component of the DC / DC step-down means 32 can be lowered, the cost can be suppressed.

<Effect>
As described above, according to the engine generator 10 according to the present embodiment described in detail, the control device 6 has the output voltage, the output current, and the output power of the step-down chopper 321 in the DC / DC step-down means 32 with predetermined limits. If it is within the value, the output voltage Vo output from the step-down chopper 321 of the DC / DC step-down means 32 is increased at a duty ratio α: 100%, and the output voltage of the step-down chopper 321 in the DC / DC step-down means 32, or A command circuit 61 is provided for decreasing the output voltage Vo output from the step-down chopper 321 of the DC / DC step-down means 32 at a duty ratio α = 0% if the output current or output power exceeds a predetermined limit value. The condition of the output change of the step-down chopper 321 in the DC / DC step-down means 32 is judged by a simple program, and the output change in the DC / DC step-down means 32 is determined. The pressure chopper 321 can be promptly commanded. Therefore, the response speed of the voltage conversion in the DC / DC step-down means 32 can be increased also in the case of dealing with a large inrush current at the time of starting, such as when starting a motor or the like. Therefore, the electric power output from the alternator 2 can be increased in a short time, and the electric power taken out from the power storage means 4 can be decreased. As a result, in order to cope with a temporary increase in power supplied to the load 8, the power storage capacity of the power storage unit 4 does not need to be increased.
Therefore, according to the present embodiment, in the engine generator 10 capable of assisting power by the power storage means 4, the power supply from the power storage means 4 can be reduced with respect to the temporary increase in power supplied to the load 8. It is possible to provide an engine generator 10 that can be reduced in size.

  Further, according to the present embodiment, since the command circuit 61 is provided with hysteresis in the output current determination condition, it is possible to prevent the output current of the step-down chopper 321 in the DC / DC step-down means 32 from becoming excessive. Can do. Therefore, the constituent elements of the DC / DC step-down means 32 can be made small in current rating, so that the DC / DC step-down means 32 can be reduced in size and cost can be reduced.

  Although the engine generator 10 according to the present embodiment has been described in detail above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. For example, in this embodiment, when the load 8 is stopped, the engine control unit (ECU) 62 performs control so as to maintain an idling state in which the engine 1 is rotated at a predetermined rotational speed. There is no need to limit. For example, the engine 1 may be stopped when the load 8 is stopped for a predetermined time or longer.

1 Engine 2 Alternator 3 Converter 4 Power storage means (capacitor)
DESCRIPTION OF SYMBOLS 5 Inverter 6 Control apparatus 8 Load 31 Rectification means 32 DC / DC step-down means 61 Command circuit 62 Engine control apparatus (ECU)
321 Step-down chopper Vs limit value (maximum voltage limit value)
Is limit value (current maximum limit value)
Ps limit value (maximum power limit value)
Vi voltage Vo Output voltage

Claims (2)

An engine, an alternator driven by the engine and outputting alternating current, a rectifying means for rectifying the alternating current output from the alternator and converting it into direct current, and a direct current output from the rectifying means to a preset voltage DC / DC step-down means for conversion, power storage means charged by a part of the direct current output from the DC / DC step-down means, and direct current output from the DC / DC step-down means and the power storage means are preset. An inverter that converts the alternating current into a frequency and outputs it to a load, and controls the increase / decrease of the engine speed and the DC / DC step-down means in accordance with the amount of power output from the inverter to the load An engine generator comprising a device,
When the load increases , the control device includes the DC / DC step-down means if the output voltage, output current and output power of the step-down chopper in the DC / DC step-down means are within predetermined limits. When the output from the step-down chopper is increased to 100% duty ratio and the load is decreased , the output voltage, output current, or output power of the step-down chopper in the DC / DC step-down means is An engine generator provided with a command circuit for decreasing the output current when the output from the step-down chopper in the DC / DC step-down means is a duty ratio of 0% if a predetermined limit value is exceeded. The engine generator according to claim 1, wherein
The engine generator according to claim 1, wherein the command circuit is provided with hysteresis for determining the condition of the output current.

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