JP4553292B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device, and in particular, has a generator driven by an engine and can keep the number of rotations of an engine waiting in a no-load operation state low, and is good when a load is applied. The present invention relates to a power supply device that exhibits responsiveness.

  Power generation devices such as engine-driven generators are widely used as power supply devices for various purposes from portable to emergency. In a power supply device with a relatively small output, for example, when a load that temporarily flows a large current such as a mercury lamp load or an electric motor load is connected, an overload condition occurs temporarily, and the engine and generator rotate. The number may drop and stall (engine stall) may occur. That is, when a temporary overload condition occurs, the engine speed decreases, and this decrease causes a decrease in the output of the generator, resulting in a stall due to a vicious cycle of falling into a further overload condition. Therefore, only about 1/3 of the inductive load such as a motor load can be used with respect to the rating of the engine-driven generator.

  In order to cope with this, it has been proposed to limit the load to a range in which the engine can maintain the maximum output operation state, eliminate the overload state as soon as possible, and start up the load. For example, in the following Patent Document 1, when it is determined that the fuel supply amount to the engine is approximately the maximum, but it is not determined that the engine speed is increasing at a change rate of a predetermined value or more. An engine speed control device is described that maintains and controls the engine at a substantially maximum output state by reducing the load.

Moreover, the following patent document 2 describes an inverter generator that accommodates a shortage of electric power from a battery with respect to a temporary overload, and the following patent document 3 describes an energy saving operation in a light load region. For the purpose of illustration, an auto-throttle device for an engine generator that reduces the engine speed in a light load state is described.
Japanese Patent No. 2740567 JP 2003-102200 A Japanese Utility Model Publication No.8-11073

  As described in Patent Documents 1 and 2, various countermeasures have been taken for temporary overload. As for the light load region, as described in Patent Document 3 mentioned above, it has been proposed to reduce the engine speed to achieve energy-saving operation, thereby achieving a certain degree of energy saving.

  However, the minimum number of revolutions of the standby engine in the no-load operation state is required to be a number of revolutions that can secure a load voltage and guarantee that the engine will not stall when a load is applied. For this reason, the number of rotations of the waiting engine cannot be significantly reduced.

  The present invention solves the above-described problem, and in a power supply apparatus having a generator driven by an engine, it is possible to significantly reduce the number of rotations of an engine on standby in a no-load operation state as compared with the conventional one. In addition, an object is to improve the responsiveness when a load is applied.

In order to solve the above problems, the present invention relates to a generator driven by an engine, a rectifier circuit that rectifies the output of the generator, and converts the output of the rectifier circuit into alternating-current power having a predetermined frequency. In a power supply device having an inverter that outputs to a battery, a battery as a power source, and a DC-DC converter that supplies power from the battery to the input side of the inverter, the engine is operated at idling speed in a no-load state. A rotation speed adjustment device that increases the rotation speed of the engine in response to an increase in load, and when the load is connected in the no-load state, the rotation speed adjustment device causes the rotation speed of the engine to be applied to the load. together configured to be powered to the load from the battery to be raised corresponding to the target rotational speed, the rotational speed of the engine is the target speed Until rises to lower predetermined rotational speed is first characterized in that configured as power supply to the load from the generator is stopped.

Further, according to the present invention, in a state where the rotational speed of the engine has increased to the predetermined rotational speed or more, the generator and the battery are both connected until the rotational speed of the engine reaches a target rotational speed corresponding to a load. powered to the load, when the rotation speed of the engine reaches the target rotation speed corresponding to the load is a second feature that is configured as power supply to the load is stopped from the battery.

Further, according to the present invention, the DC-DC converter is a bidirectional DC-DC converter, and the target rotational speed is set so as to obtain a power generation amount sufficient to drive a load only by the generator output. the battery is a third aspect of is charged with power supplied from the generator through the bi-directional DC-DC converter according to the charge state.

Furthermore, the present invention is characterized in that a regulator is provided between the rectifier circuit and the inverter, and the bidirectional DC-DC converter is provided between a connection point between the rectifier circuit and the regulator and the battery. There is a fourth feature.

  According to the first feature of the present invention, it is possible to significantly reduce the idling speed of the engine that is waiting in the no-load operation state as compared with the conventional one.

Further, for taking out the electric power from the battery alone without removing power from the generator to rise from a low rather set idle speed to a predetermined rotational speed, the rotational speed of the engine along with allowing rapid supply of power to the load Can be raised quickly. As a result, it is possible to obtain excellent performance in both load response and engine start-up response.

Also. According to the second feature, when the engine speed sufficiently increases and reaches the target speed corresponding to the load, power is supplied only from the generator to the load, so that the burden on the battery can be reduced.

Moreover, according to the 3rd characteristic, while being able to supply electric power stably from a generator to a load, a battery can fully be charged with the electric power from a generator as a part of load. In addition, since it is possible to charge the battery by using a circuit for taking out power from the battery, the same circuit is used for taking in and out power from the battery, that is, taking out the power from the battery and charging the battery by the output of the generator. Can be done easily and reliably.

Further, according to the fourth feature, fluctuations in the secondary side output of the bidirectional DC-DC converter can be absorbed by the regulator so that the fluctuations do not directly affect the inverter side.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the concept of a power supply device according to the present invention. In the figure, the generator 1 is composed of, for example, a three-phase multipolar magnet generator. The generator 1 is an engine-driven generator that is connected to the engine 2 and driven by the engine 2, and is an electric generator that can also operate as an engine starting motor.

  The rectifier circuit 3 rectifies the output of the generator 1, and also converts the DC voltage applied from the output side into a three-phase AC voltage and applies it to the generator 1 to operate as an engine starting motor. It also functions as a driving inverter.

  The power conversion unit 4 includes a DC regulator 4-1 and an inverter 4-2, converts the output of the rectifier circuit 3 or a DC-DC converter 5 described later to AC power having a predetermined frequency, and outputs it to the load side. The DC regulator 4-1 of the power conversion unit 4 prevents the output fluctuation of the DC-DC converter 5 from reaching the inverter 4-2.

  The DC-DC converter 5 boosts the voltage of the battery 6 and outputs the boosted DC voltage to the output side of the rectifier circuit 3. Further, when a sufficient voltage is output from the rectifier circuit 3 and the remaining capacity of the battery 6 is small, the DC-DC converter 5 supplies the output of the rectifier circuit 3 to the battery 6 and charges it. Hereinafter, the battery 6 side of the DC-DC converter 5 may be referred to as a primary side, and the rectifier circuit 3 side may be referred to as a secondary side. The battery 6 is a 12V battery generally used as a cell starter, for example.

  Next, the operation of FIG. 1 will be described. Hereinafter, power supply to the load by the generator 1 driven by the engine 2 is referred to as “generator power generation”, and power supply to the load by the battery 6 is referred to as “battery power generation”.

  When starting the engine 2, the DC voltage of the battery 6 is boosted by the DC-DC converter 5, and the boosted DC voltage is applied to the drive inverter (rectifier circuit) 3. The drive inverter 3 is switching-driven by a start command, converts a DC voltage into a three-phase AC voltage, and supplies the AC voltage to the generator 1. Thereby, the generator 1 is started as an engine starting motor. When the engine 2 is started, the generator 1 is driven by the engine 2. The drive inverter 3 stops the switching operation and functions as a rectifier circuit.

  If the load is not connected to the output side of the power converter 4, the engine 2 is driven at idling speed. The idling rotational speed is obtained by controlling the throttle opening of the rotational speed adjusting device of the engine 2 with an electronic governor according to the load current 0.

  When a load is connected to the output side of the power conversion unit 4, a current taken out from the battery 6 through the DC-DC converter 5 to the load side (hereinafter referred to as a DDC current) is equal to or less than a specified value (light load). If the remaining capacity of the battery 6 is equal to or greater than a specified value, power is supplied from the battery 6 to the load through the DC-DC converter 5. That is, only battery power generation is performed.

  When the DDC current exceeds the specified value and / or the remaining capacity of the battery 6 is less than the specified value, the actual engine speed increases toward the target engine speed corresponding to the load at that time. Is done. At this time, since the output from the generator 1 side is smaller than the output from the battery 6 side, the output is not taken out from the generator 1 side, and the actual rotational speed of the engine 2 rapidly increases. When the actual rotational speed of the engine 2 exceeds a predetermined value, both the battery 5 and the generator 1 are fed to the load. That is, both battery power generation and generator power generation are performed.

  When the actual rotational speed of the engine 2 reaches the target rotational speed, the output voltage of the rectifier circuit 3 is sufficiently increased. Therefore, the voltage conversion from the primary side to the secondary side of the DC-DC converter 5 is stopped and battery power generation is performed. Stopped.

  When the load changes in this state, the actual rotation speed of the engine 2 is changed by the rotation speed adjusting device accordingly, and power corresponding to the load is supplied by the generator power generation. At this time, the battery 6 is charged with the output of the rectifier circuit 3 if it is not fully charged. Usually, the operation in this state is continued.

  If the load is equal to or less than the specified value and the remaining capacity of the battery 6 is equal to or greater than the specified value, the actual engine speed of the engine 2 is reduced to an idle engine speed. At this time, if a light load is connected, only battery power generation is performed. Here, when the power supply capacity for the load is insufficient due to a decrease in the remaining capacity of the battery 6 or the like, the actual rotational speed of the engine 2 is increased again and switched to generator power generation. At the same time, the battery 6 is charged with the output of the generator power generation.

  As described above, the engine 2 is driven at the idle rotation speed in the no-load state, and when the load is connected in the no-load state, only the battery power generation is performed until the actual rotation speed of the engine 2 reaches the predetermined rotation speed. If the actual rotational speed of the engine 2 exceeds a predetermined rotational speed, both battery power generation and generator power generation are performed. If the actual rotational speed of the engine 2 further increases and reaches the target rotational speed according to the load at that time, the generator is generated. Only power generation is performed. The battery 6 is charged with the output of the rectifier circuit 3 through the DC-DC converter 5 if the remaining capacity is small.

  FIG. 2 is a flowchart for explaining the operation of the power supply apparatus. The engine 2 waiting in the no-load state is driven at an idle rotation speed close to the lowest, for example, 1500 rpm (Ne = 1500 rpm) for maintaining the rotation. When a load is applied in this state (S1), battery power generation (Batt power generation) is first performed. At this time, it is detected whether the load current, that is, the DDC current from the battery 6 exceeds a specified value (S2), and whether the remaining capacity of the battery 6 is less than a specified value (S3). Whether or not the remaining capacity of the battery 6 is less than a specified value can be detected by, for example, determining completion of charging of the battery 6 and outputting a charging completion signal.

  If the DDC current is not more than the specified value and the remaining capacity of the battery 6 is not less than the specified value (S4), battery power generation is continued. If the DDC current exceeds the specified value and / or the remaining capacity of the battery 6 is less than the specified value, the actual rotational speed Ne of the engine 2 is increased toward the target rotational speed corresponding to the load. (S5).

  When the actual rotational speed Ne of the engine 2 exceeds a predetermined value, both battery power generation and generator power generation are performed. This predetermined value means the rotational speed at which the output voltage of the power conversion unit 4 becomes substantially the same as the output voltage of the DC-DC converter 5, for example, 2500 rpm. When the actual rotational speed Ne of the engine 2 reaches this rotational speed, both the battery power generation and the generator power generation supply current to the load. However, until sufficient current is supplied to the load, that is, power generation corresponding to the load. The actual rotational speed Ne of the engine 2 increases until the target rotational speed at which an output is obtained is reached.

  Whether or not sufficient current is supplied to the load is determined by the primary DC voltage of the DC regulator 4-1 of the power converter 4. The target primary side DC voltage is obtained from the actual rotational speed Ne of the current engine 2 and compared with the actual primary side DC voltage. If the actual primary side voltage is low, it means that the input is insufficient. The actual rotational speed Ne of 2 is further increased. When the difference between the actual primary DC voltage and the target primary DC voltage is within the allowable range, it is determined that the actual rotational speed Ne of the engine 2 has reached the target rotational speed corresponding to the load.

  When the actual rotational speed Ne of the engine 2 reaches the target rotational speed corresponding to the load at that time (S6), power supply from the battery 6 side, that is, battery power generation is stopped, and only generator power generation is performed.

  When the load changes in this state, the actual rotational speed Ne of the engine 2 is changed accordingly, and power corresponding to the load is supplied by generator power generation in a range where the change amount of the load is not so large. For example, when the load increases, the primary side DC voltage of the DC regulator 4-1 decreases as described above, and thus becomes lower than the target primary side DC voltage obtained from the current actual speed Ne of the engine 2. For this reason, the actual rotational speed Ne of the engine 2 is increased so that the difference between the actual primary DC voltage and the target primary DC voltage falls within the allowable range. At this time, when the load increase amount is large and the difference between the target rotational speed and the actual rotational speed Ne becomes large, current supply to the load is performed again from both battery power generation and generator power generation.

  On the contrary, when the load is reduced, the actual rotational speed Ne of the engine 2 is lowered and the electric power generated by the generator power generation is reduced. If the battery 6 is not fully charged, the battery 6 is charged with the output of the rectifier circuit 3. Usually, the operation in the current supply state only by the generator power generation is continued within a range in which the difference between the target rotation speed and the actual rotation speed Ne is small (S6).

  When it is detected that the load is not more than a specified value, for example, 400 W or less (S7) and the remaining capacity of the battery 6 is not less than the specified value (S8), the actual rotational speed Ne of the engine 2 is decreased (S9) Only the battery power generation is performed (S10). If the power supply capacity for the load is insufficient due to a decrease in the remaining capacity of the battery 6 or the like, the actual rotational speed Ne of the engine 2 is increased again (S2 to S5) and switched to generator power generation. At the same time, the battery 6 is charged with the output of the generator power generation. Further, when the generator power generation state is changed to the no-load state (S7 to S9), the actual rotational speed Ne of the engine 2 becomes the idle rotational speed (S11).

  When the actual rotational speed Ne of the engine 2 has reached the target rotational speed corresponding to the load (S6) and the generator power generation cannot cope with the overload state, the generator power generation is assisted by battery power generation. As described above, the power supply is performed in the form of power supply, for example, when the input voltage of the power conversion unit 4 is less than the target voltage and the throttle opening of the rotation speed adjustment device of the engine 2 exceeds a predetermined value, or power conversion Even when the input voltage of the unit 4 is lower than the target voltage by a predetermined value or more, power can be supplied to the load in such a manner that generator power generation is assisted by battery power generation. Note that the case where the input voltage of the power conversion unit 4 is lower than the target voltage by a predetermined value or more is for providing a hysteresis characteristic to prevent frequent switching. Further, when the input voltage of the power conversion unit 4 is equal to or higher than the target voltage, the throttle opening is equal to or less than a predetermined value, or the assist duration time exceeds the set time, the assist is stopped.

  When the battery 6 spontaneously discharges due to long-term non-use and the remaining capacity decreases, and the engine 2 cannot be started with the electric power, first, the engine 2 is manually started by a manual starter such as a recoil starter to generate generator power. What is necessary is just to make it charge the battery 6.

  FIG. 3 is a circuit diagram showing an example of a specific circuit of the power supply device according to the present invention. The same or equivalent parts as those in FIG. The three-phase generator 1 is connected to an engine (not shown). The output side of the generator 1 is connected to a rectifier circuit (drive inverter) 3. Switching elements (hereinafter referred to as FETs) 3-1 to 3-6 such as FETs are connected in parallel to each rectifying element (diode) of the rectifier circuit 3, and these FETs 3-1 to 3-6 are A drive inverter that converts the DC voltage into a three-phase AC voltage and applies it to the generator 1 by turning on and off is configured.

  The rectifying element constituting the rectifying circuit 3 may be a parasitic diode of a switching element such as an FET, or may be a separately connected junction diode.

  The DC regulator 4-1 of the power conversion unit 4 includes, for example, an FET, a choke coil, a capacitor, a diode, and the like, and the FET is PWM-modulated to smooth and adjust the output of the rectifier circuit 3. The inverter 4-2 is configured by connecting, for example, four FETs 4-2-1 to 4-2-4.

  The DC-DC converter 5 is capable of bidirectionally exchanging power between the battery 6 and the output side of the rectifier circuit 3, and includes a primary side low voltage side winding 5-1-1 and a secondary side high voltage. A transformer 5-1 including a side winding 5-1-2 is included. The step-up ratio of the DC-DC converter 5 is determined by the winding ratio of the low-voltage side winding 5-1-1 and the high-voltage side winding 5-1-2.

  The low voltage side switching unit 5-2 is inserted on the low voltage side winding 5-1-1 side, and the high voltage side switching unit 5-3 is inserted on the high voltage side winding 5-1-2 side. The low-voltage side switching unit 5-2 is configured by, for example, four FETs 5-2-1 to 5-2-4 being bridge-connected, and the high-voltage side switching unit 5-3 is similarly configured with four FETs 5-3-1 to 5-2. It is composed of 5-3-4.

  Rectifiers such as diodes are connected in parallel to the FETs 5-2-1 to 5-2-4 and 5-3-1 to 5-3-4 of the low-voltage side switching unit 5-2 and the high-voltage side switching unit 5-3. Is done. These rectifying elements may also be FET parasitic diodes, or may be separately connected junction diodes. If the rectifying elements connected in parallel are combined, the low-voltage side switching unit 5-2 and the high-voltage side switching unit 5-3 can be considered as switching / rectifying units, respectively.

  An LC resonance circuit 5-4 is inserted on the high-voltage side winding 5-1-2 side of the transformer 5-1. The LC resonance circuit 5-4 has a sinusoidal current that flows when at least one of the low-voltage side switching unit 5-2 and the high-voltage side switching unit 5-3 is driven, and reduces switching loss. It functions so as not to cause FET destruction. This is because the FET can be easily turned on and off near the zero cross point of the sinusoidal current. The LC resonance circuit 5-4 is not limited to the secondary side and may be provided on the primary side.

  The FETs 5-2-1 to 5-2-4 of the low-voltage side switching unit 5-2 and the FETs 5-3-1 to 5-3-4 of the high-voltage side switching unit 5-3 are control circuits (not shown) including a CPU or the like. Z)). Capacitors 7 and 8 connected to the primary side and the secondary side are output smoothing capacitors.

  As is well known, the low-voltage side switching unit 5-2 and the high-voltage side switching unit 5-3 include a pair of FET 5-2-1 and 5-2-4, FET 5-2-2 in the low-voltage side switching unit 5-2. And 5-2-3 are alternately turned on and off, and in the high-voltage side switching unit 5-3, a pair of FETs 5-3-1 and 5-3-4, and FETs 5-3-2 and 5-3-3. Are driven to be alternately turned on and off.

  If the FETs 3-1 to 3-6 of the drive inverter 3 are PWM-driven as is well known, the generator 1 can be operated as an engine starting motor. At this time, the FETs 3-1 to 3-6 can be synchronously driven without a sensor by using the fact that the current distribution is changed by the counter electromotive voltage according to the movement of the generator (motor) 1 to determine the phase. If the FETs 3-1 to 3-6 are not driven, the drive inverter portion operates as a rectifier circuit for the output of the generator 1.

  The DDC current can be detected by a current detection resistor 5-5 disposed in the DC-DC converter 5, and a current transformer or the like is provided at the connection between the rectifier circuit (drive inverter) 3 and the high voltage side switching unit 5-3. It can also detect by arranging. The remaining capacity of the battery 6 can be detected by a decrease in the terminal voltage, current, or remaining capacity of the battery 6, and can be detected based on the internal resistance value estimated from the temperature and current of the battery 6 or from current fluctuation and voltage change. It can also be detected by estimating the voltage.

  Although the embodiment has been described above, in the present invention, the DC-DC converter 5 is configured as a bidirectional DC-DC converter that drives the primary side and the secondary side in perfect synchronization, that is, with the same drive signal. You can also. With this configuration, the DC-DC converter 5 performs bidirectional power conversion based on the relative voltage difference between the primary side and the secondary side depending on the winding ratio of the transformer. Charging can be performed easily and reliably in the same circuit.

It is a block block diagram which shows the concept of the power supply device which concerns on this invention. It is a flowchart for demonstrating operation | movement of the power supply device of FIG. It is a circuit diagram which shows an example of the specific circuit of the power supply device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Engine, 3 ... Rectifier circuit (drive inverter), 3-1 to 3-6, 4-1 to 4-4, 5-2-1 to 5-2 -4, 5-3-1 to 5-3-4 ... FET, 4 ... power converter, 4-1 ... DC regulator, 4-2 ... inverter, 5 ... DC- DC converter, 5-1 ... transformer, 5-1-1 ... low voltage side winding, 5-1-2 ... high voltage side winding, 5-2 ... low voltage side switching unit, 5- DESCRIPTION OF SYMBOLS 3 ... High voltage side switching part, 5-4 ... LC resonance circuit, 5-5 ... DDC current detection resistor, 6 ... Battery, 7, 8 ... Smoothing capacitor

Claims (4)

A generator driven by an engine; a rectifier circuit that rectifies the output of the generator; an inverter that converts the output of the rectifier circuit into alternating-current power of a predetermined frequency and outputs the AC power; a battery as a power source; And a DC-DC converter for supplying electric power of the battery to the input side of the inverter,
In the no-load state, the engine is operated at idling rotational speed, and equipped with a rotational speed adjusting device that increases the rotational speed of the engine according to an increase in load,
When a load is connected in the no-load state, power is supplied from the battery to the load until the engine speed is increased to a target engine speed corresponding to the load by the engine speed adjusting device. In addition, the power supply device is configured such that the power supply from the generator to the load is stopped until the engine speed increases to a predetermined engine speed lower than the target engine speed.   In a state where the rotational speed of the engine has risen above the predetermined rotational speed, power is supplied to the load from both the generator and the battery until the rotational speed of the engine reaches a target rotational speed corresponding to a load, 2. The power supply device according to claim 1, wherein power supply from the battery to the load is stopped when an engine speed reaches the target speed corresponding to a load.   The DC-DC converter is a bidirectional DC-DC converter, and the target rotational speed is set so that a power generation amount sufficient to drive a load is obtained only by the generator output, and the battery is charged The power supply device according to claim 2, wherein the power supply device is charged with electric power supplied from the generator through the bidirectional DC-DC converter according to a state. 4. A regulator is provided between the rectifier circuit and the inverter, and the bidirectional DC-DC converter is provided between a connection point between the rectifier circuit and the regulator and the battery. The power supply device described in 1.

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