JPH11341823A - Ac power supply and method of synchronously operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC power supply, capable of reliably matching the phase of a single-phase AC voltage to be outputted by a portable generator, an AC power supply of one's own, with that of an AC voltage to be outputted by an other AC power supply. SOLUTION: Time lags are compared between the zero-cross point of a sine wave form formed, by the PWM control signal controlling an inverter circuit 130 and that in the wave form of the voltage across the output terminals of its portable generator. If both zero-cross points are shifted, the interval of the clock pulses which form the PWM control signal is finely adjusted. This fine adjustment reduces the time lags of both zero-cross points.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable generator as an AC power supply device capable of outputting a single-phase AC voltage such as 100 volts by rotating a generator by an engine.

[0002]

2. Description of the Related Art Today, small generators that can be moved to a required place using a gasoline engine or a diesel engine and that can produce an output of several kilowatts have been frequently used. Have been. The portable generator as an AC power supply that can be moved has a single phase of 50 Hz or 60 Hz by setting the average output voltage to about 100 volts and the engine speed to a constant speed. There was a generator that output AC voltage. However, recently, there is a type in which an output voltage of an AC generator rotated by an engine is temporarily converted to a DC voltage, and further, an output voltage having a constant frequency of 50 Hz or 60 Hz is formed using an inverter (for example, JP-A-63-114527, JP-A-63-302724
issue).

Incidentally, a small-sized portable generator capable of outputting about several kilowatts to about 10 kilowatts using an engine is not limited to a case where the generator is carried to a place of use and the power generation operation is always performed in a movable state. In some cases, such as when the usage period in a specific place continues, the device may be fixedly installed and operated. In a portable generator employing this inverter, as shown in FIG. 6, an AC generator 50 rotated by an engine, a rectifier diode 115 and a thyristor 1 are provided.
DC power supply unit 1 with a DC voltage generation circuit 110 using a large-capacity capacitor 121 with a required number of capacitors in parallel
20, and an inverter circuit 13 using a power transistor
0 and a low-pass filter 140. Further, as a control circuit for driving and controlling the power circuits such as the DC voltage generation circuit 110 and the inverter circuit 130, a PWM signal generation circuit
250, a voltage limiting circuit 240, an overload detection circuit 260, an inverter drive circuit 255, and the like. Further, the portable generator 100 also includes a smoothing circuit 210 and a constant voltage circuit 235 as a power supply unit for driving these control circuits.

As an AC generator 50 for rotating a rotor by this engine, a generator having a three-phase output winding 51 and a single-phase output winding 55 is often used. The three-phase output winding 51 has a maximum output of several hundred volts and can output about several tens of amps, and the single-phase output winding 55 has several tens of volts and can output about tens of amps. Many. The DC voltage generation circuit 110 to which the output terminal of the three-phase output winding 51 is connected,
A rectifying bridge circuit using three rectifying diodes 115 and three thyristors 111 is connected. Both output terminals of the rectifying bridge circuit are connected to both ends of a main smoothing capacitor 121 serving as a DC power supply unit 120, and a capacitor is connected. It charges the 121.

The gate terminal of each thyristor 111 in the DC voltage generating circuit 110 is connected to a voltage limiting circuit 240,
By controlling the conduction angle of each thyristor 111, the voltage across the main smoothing capacitor 121 serving as the DC power supply unit 120 is adjusted. The inverter circuit 130 is configured by a bridge circuit using four power transistors. In the inverter circuit 130, the first transistor 131
And the third transistor 133 are connected in series to the DC power supply unit 120, and the second transistor 132 and the fourth transistor 134 are connected in series to the DC power supply unit 120. Also, the first
A middle point between the transistor 131 and the third transistor 133 is connected to a first output terminal 151 via a low-pass filter 140, and a middle point between the second transistor 132 and the fourth transistor 134 is connected to a second output terminal via a low-pass filter 140. Connected to terminal 152. Further, the base of the first transistor 131 and the base of the fourth transistor 134 are connected in common to the inverter drive circuit 255, and the base of the second transistor 132 and the base of the third transistor 133 are connected in common to the inverter drive circuit 255. doing.

[0006] The inverter drive circuit 255
The first PWM signal output to the transistor 131 and the fourth transistor 134 and the second PWM signal output to the second transistor 132 and the third transistor 133 are high-frequency pulse signals of several kilohertz or more. The pulse width is sequentially changed in a cycle of 50 Hz or 60 Hz, and the amount of change in the pulse width is a signal that is sequentially increased or decreased in a sinusoidal manner.

The first PWM signal and the second PWM signal have opposite phases. For this reason, when the first transistor 131 and the fourth transistor 134 are made conductive by the first PWM signal to set the midpoint between the first transistor 131 and the third transistor 133 to the voltage VD of the DC power supply unit 120, the second transistor 132 The midpoint of the second transistor 132 and the fourth transistor 134 is set to 0 volt, and the second PWM signal is
When the third transistor 133 is turned on, the midpoint between the first transistor 131 and the third transistor 133 is set to 0 volt, and the midpoint between the second transistor 132 and the fourth transistor 134 is set to the voltage VD. It is said.

As shown in FIG. 7A, the midpoint potential between the first transistor 131 and the third transistor 133 switches between 0 volts and the voltage VD of the DC power supply 120 at a high speed, The duration of VD changes sequentially. or,
As shown in FIG. 7B, the midpoint potential between the second transistor 132 and the fourth transistor 134 also switches between the voltage VD of the DC power supply 120 and 0 volts at a high speed, and the duration of the DC power supply voltage VD sequentially. Change.

For this reason, the first output voltage and the second output voltage that have passed through the low-pass filter 140 are, as shown in FIG.
A sine wave voltage of 50 Hz or 60 Hz, and
The voltage of the first output terminal 151 and the voltage of the second output terminal 152 are
50 Hz or 60 with maximum and minimum values shifted by half a cycle
It is formed as a hertz AC output voltage. The single-phase output winding 55 of the AC generator 50 is connected to a smoothing circuit 210 in the control power supply circuit, as shown in FIG.

The smoothing circuit 210 includes a rectifying diode 211.
And a smoothing capacitor 215, a rectifier diode 211 is inserted between the output terminal of the single-phase output winding 55 and the smoothing capacitor 215, and the output voltage of the single-phase output winding 55 causes the smoothing capacitor 215 to The battery is charged to form a DC voltage. The number of the rectifying diodes 211 is not limited to one as shown in FIG. 6, but a smoothing capacitor may be charged as a full-wave rectifying bridge using four rectifying diodes.

Then, the output terminal of the smoothing circuit 210 is connected to a constant voltage circuit 235, and the constant voltage circuit 235 forms a predetermined voltage for driving a control circuit. Further, the constant voltage circuit 235 connects the negative terminal to the positive terminal of the DC power supply unit 120,
The positive terminal of the constant voltage circuit 235 is connected to the voltage limiting circuit 240, the PWM signal generating circuit 250, and the inverter drive circuit 255.

The voltage limiting circuit 240 is constituted by using a resistor and a comparator, and a first reference voltage resistor 245 and a second reference voltage resistor 246 are connected in series to the positive terminal of the constant voltage circuit 235. Between the first reference voltage resistor 245 and the second reference voltage resistor 246 to the reference input terminal of the comparator 243. . Also, the first
The voltage dividing resistor 248 and the second voltage dividing resistor 249 are connected in series between the positive terminal of the constant voltage circuit 235 and the negative terminal of the DC power supply unit 120, and the first voltage dividing resistor 248 and the second voltage dividing resistor 249 are connected in series. The midpoint of the two-divided resistor 249 is connected to the comparison input terminal of the comparator 243.

Further, the output terminal of the comparator 243 is connected to the + terminal of the constant voltage circuit 235 via the control resistor 241 and also to the gate terminal of each thyristor 111 in the DC voltage generation circuit 110. ing. When the output terminal of the comparator 243 is connected to the gate terminal of each thyristor 111, it is connected via the protection resistor 117. Therefore, in the voltage limiting circuit 240, the constant voltage circuit 2 of the control power supply circuit is used.
The constant voltage formed at 35 is divided by the first reference voltage resistor 245 and the second reference voltage resistor 246 to form a constant reference voltage, and the constant voltage reference voltage is compared. Input to the reference input terminal of the detector 243.

Further, a voltage obtained by adding the output voltage of the DC power supply unit 120 and the constant voltage formed by the constant voltage circuit 235 is divided by the first voltage dividing resistor 248 and the second voltage dividing resistor 249, and the detection voltage is obtained. And the detection voltage can be input to the comparison input terminal of the comparator 243. Therefore, the detection voltage input to the comparison input terminal fluctuates due to the voltage fluctuation of the DC power supply unit 120, and this detection voltage is connected to the first reference voltage resistor 245 and the second reference voltage resistor 245.
When the voltage is lower than the reference voltage formed by the reference voltage resistor 246, the output of the comparator 243 is set to a positive potential.

Therefore, the gate potential of the thyristor 111 can be made higher than the cathode potential of the thyristor 111, and a gate current is supplied to each thyristor 111 via the control resistor 241 to make each thyristor 111 conductive. Will be. Therefore, when the output voltage of the three-phase output winding 51 becomes higher than the voltage of the DC power supply unit 120, power is supplied to the DC power supply unit 120, and the voltage of the DC power supply unit 120 is increased.

When the voltage of the DC power supply 120 rises and the detection voltage input to the comparator 243 becomes equal to the reference voltage, the output of the comparator 243 becomes 0, and the gate potential of each thyristor 111 becomes the cathode potential. Equal, each thyristor 11
1 becomes non-conductive. As described above, the voltage limiting circuit 240 performs charging from the AC generator 50 when the voltage formed by the DC power supply unit 120 becomes lower than a certain voltage, and stops charging when the voltage reaches the certain voltage. Can be constantly maintained at a constant voltage VD set by the voltage limiting circuit 240 at about 170 volts to 200 volts.

Then, the potentials of the first output terminal 151 and the second output terminal 152 are changed at a constant period of 50 Hz or 60 Hz by the inverter circuit 130, and the first output terminal 151 is changed.
The maximum potential difference between the voltage of the second output terminal 152 and the voltage of
A single-phase AC voltage having an average voltage of 100 volts is output by applying 41 volts. A PWM signal generation circuit 250 that forms a PWM control signal for controlling the inverter circuit 130 includes:
A PWM control signal is formed from a reference sine wave such as 50 Hz or 60 Hz and a triangular wave and output to the inverter drive circuit 255.

The reference sine wave of the PWM signal generation circuit 250 is the frequency of the voltage output from the output terminal.
It is formed in accordance with a predetermined frequency such as Hertz or 60 Hertz, adjusts the ratio between the reference sine wave voltage and the triangular wave voltage, and outputs the output voltage VD of the DC The frequency of the pulse signal used as the PWM control signal, the pulse width, and the amount of change in the pulse width are determined by the characteristics of the circuit 130 and the low-pass filter 140.

Further, in the portable generator 100, the detection resistor 261 is provided between the DC power supply 120 and the inverter circuit 130.
Is provided. The overload detection circuit 260 includes a detection resistor 261 and an arithmetic circuit unit 265, and when a current value exceeding a rated current value is detected, a stop signal is added in consideration of time according to a magnitude exceeding the rating. This is output to the inverter drive circuit 255.

The arithmetic circuit section 265 uses various circuits using a comparator, a capacitor, and a resistor. In consideration of the characteristics of the elements constituting the power circuit, the arithmetic circuit section 265 often has twice the rated current. When the current flows through the inverter drive circuit 255, the stop signal is immediately output and the first stop signal is output from the inverter drive circuit 255.
The output of the PWM signal and the second PWM signal is stopped.
When a current slightly exceeding the rated current is detected, a stop signal is output to the inverter drive circuit 255 when a time of several seconds to several minutes has been maintained.

As described above, the portable generator 100 as an AC power supply device which once rectifies the three-phase AC by the DC voltage generation circuit 110 and converts the DC voltage generated by the DC power supply unit 120 to the AC voltage again by the inverter circuit 130. Is the alternator 50
, Ie, the number of revolutions of the engine, to constantly generate an electric power according to the load, and to form an AC output voltage of a constant frequency and voltage.

Accordingly, the engine speed is adjusted in accordance with the load fluctuation, the engine speed is increased in the case of a high load, and the engine speed is lowered in the case of a low load, and the necessary energy is adjusted according to the load. Since it is sufficient if the power is generated from the engine, the output can be easily adjusted according to the load, and the portable generator 100 can be made efficient. When the overload state exceeds the rated output, the operation of the inverter circuit 130 is stopped instantaneously or in accordance with the elapse of a predetermined time according to the overload state, and the output voltage is set to 0 to secure the entire circuit. It is possible to operate various electrical devices loaded within a range of several kilowatts, which is a rated output, while maintaining the rated output.

As described above, the portable generator 100 which is an AC power supply device with an engine using the inverter circuit 130 is provided.
Can output the same 100-volt single-phase AC power as a commercial power supply, and has recently been used as a power supply for various general electric appliances. As such a portable generator 100, there is a portable generator 100 that performs a voltage phase adjustment of a single-phase AC power to enable parallel operation.

In the portable generator 100 capable of performing the parallel operation, the AC output voltage and the AC output current output from the first output terminal 151 and the second output terminal 152 of the portable generator 100 are detected, and the parallel operation is performed. A PWM signal generation circuit that always outputs an output voltage that matches the output voltage and phase of another generator that operates and the voltage value and phase of the single-phase AC power output from the portable generator 100 250 (for example, JP-A-5-49174, JP-A-5-236658, and JP-A-5-244726).

In the portable generator 100, in many cases,
As shown in FIG. 8, the first stage is provided after the low-pass filter 140.
An output voltage detection circuit 340 is inserted between the output terminal 151 and the second output terminal 152, and an output current detection circuit 330 is inserted after the low-pass filter 140, so that the first output terminal 151 and the second output terminal 152 are inserted. The PWM signal generation circuit 250 is controlled by detecting the voltage and current of the single-phase AC output output from.

In this portable generator 100, similarly to the portable generator 100 shown in FIG. 6, the single-phase output winding 55 of the AC generator 50 is constituted by a smoothing circuit 210 and a constant voltage circuit 235. Connected to the control power supply unit 201, the output voltage of the single-phase output winding 55 is smoothed by a smoothing circuit 210, and a constant voltage circuit 235 forms a predetermined control voltage Vcc. However, according to the elements constituting the control circuit, the control voltage is + Vcc voltage and -V
The cc voltage may be formed by the control power supply unit 201 in some cases.

The output terminal of the three-phase output winding 51 is connected to a DC voltage generating circuit 110 which is a rectifier bridge circuit using a thyristor and a rectifier diode, and rectifies the output voltage of the three-phase output winding 51. A DC voltage is formed by charging a large-capacity capacitor serving as the DC power supply unit 120, and this DC voltage is input to the inverter circuit 130 to form a single-phase AC voltage, similarly to the above-described prior art.

In the portable generator 100 shown in FIG. 8, the stop signal from the overload detection circuit 269 is input to the voltage control circuit 240 for controlling the conduction angle of the thyristor in the DC voltage generation circuit 110. In the load state, the operation of the inverter circuit 130 is stopped, and the gate current output from the voltage control circuit 240 to the DC voltage generation circuit 110 is cut off to stop the operation of the DC voltage generation circuit 110. .

The PWM signal generating circuit 250 includes a sine wave generating circuit 270 for forming a reference sine wave, a triangular wave generating circuit 281 and a PWM control signal generating circuit 285 for forming a PWM control signal. The wave generation circuit 270 forms an accurate 50 Hz or 60 Hz reference sine wave,
The triangular wave generating circuit 281 forms a high frequency triangular wave of about several kilohertz to several tens of kilohertz, and the PWM control signal generating circuit 285 combines a reference sine wave and a triangular wave to form a pulse train whose pulse width changes sequentially. It forms a signal.

Further, the sine wave generation circuit 270 outputs an oscillation circuit 271 for outputting a high frequency signal of several megahertz to several tens of megahertz, and a clock signal of about 10 kilohertz by dividing the high frequency signal output by the oscillation circuit 271. The dividing circuit 273 forms a number of different potentials by means of a multi-stage voltage dividing resistor, and sequentially selects different potentials by a multiplexer operated by a clock signal to form a stepped sine wave of 50 Hz or 60 Hz. Pseudo-sinusoidal wave forming circuit 275 that outputs a sine wave, and a voltage adjusting circuit 277 that adjusts the peak voltage of the stepped sine wave output by the pseudo sine wave forming circuit 275 and forms a smooth sine wave from the stepped sine wave. And a low-pass filter 279.

The voltage detection signal output from the output voltage detection circuit 340 is input to a rectangular wave forming circuit 291 to form a rectangular wave signal having a zero cross point of the AC output voltage as a rising edge and a falling edge, The zero-cross signal converted into the rectangular wave signal is input to the start timing circuit 293 and the phase comparison circuit 297. The start timing circuit 293 releases the pseudo sine wave forming circuit 275 in the sine wave generating circuit 270 so that the pseudo sine wave forming circuit 275 outputs a pseudo sine wave.

When the pseudo sine wave forming circuit 275 is in the reset state and the reference sine wave is not output from the sine wave generating circuit 270, that is, when the inverter circuit 130 is not operating, the output voltage detecting circuit 340 is turned on. When a voltage change between the first output terminal 151 and the second output terminal 152 is detected, the start timing circuit 293 releases the reset of the pseudo sine wave forming circuit 275 in accordance with the zero cross signal from the rectangular wave forming circuit 291 and outputs a sine wave. The phase of the reference sine wave output from the wave generation circuit 270 and the phase of the voltage generated between the first output terminal 151 and the second output terminal 152 are matched.

When the operation of the pseudo sine wave forming circuit 275 is started, if the zero cross signal is not input to the starting timing circuit 293 within a predetermined time, the pseudo sine wave forming circuit 275 may be used.
The reset of 275 is released, and the output of the reference sine wave from the sine wave generation circuit 270 is started. Then, the output current detection circuit 33
The current detection signal from 0 is input to a rectangular wave forming circuit 295, an overload detecting circuit 269, and a limit value detecting circuit 299, and the rectangular wave forming circuit 295 outputs a zero-cross signal that matches the phase of the output current, The detection circuit 269 generates a stop signal when the rated current is exceeded, and the limit value detection circuit 299 generates a voltage adjustment signal when the current value is equal to or less than the rated current and exceeds a predetermined lower limit value and upper limit value range. It is assumed.

The rectangular wave forming circuit 295 forms a rectangular wave signal having the zero cross point of the AC output current as a rising edge and a falling edge based on the current detection signal output from the output current detecting circuit 330. The wave signal is input to the phase comparison circuit 297 as a zero-cross signal. This phase comparison circuit 297 compares the phase of the output current with the phase of the output voltage based on the zero-cross signal based on the current detection signal and the zero-cross signal based on the voltage detection signal, and determines whether the current phase is later than the voltage phase. Outputs the added signal as a phase adjustment signal to the frequency divider 273, and
If the current phase is more advanced than the voltage phase, the subtraction signal is output to the frequency divider 273 as a phase adjustment signal.

The frequency dividing circuit 273 in the sine wave generating circuit 270 receives the added signal from the phase comparing circuit 297 when dividing the high frequency signal to form a clock signal of several kilohertz to tens of kilohertz. One pulse is added for every several hundred pulses of the clock signal. When a subtraction signal is input from the phase comparison circuit 297, a clock signal is formed by thinning out one pulse every several hundred pulses of the clock signal.

As described above, when the current phase lags behind the voltage phase, the pulse of the clock signal is increased to slightly advance the phase of the pseudo sine wave and thus the reference sine wave, and the current phase advances beyond the voltage phase. In this case, the phase of the reference sine wave is slightly delayed by thinning out the pulse of the clock signal, and the phase of the PWM control signal is adjusted to reduce the phase of the PWM control signal.
100 adjusts the phase of the single-phase AC voltage output.

Therefore, the other generator and the portable generator 10
0 and the first output terminal 151
When the phase of the output current is delayed with respect to the phase of the voltage between the second output terminal 152 and the phase of the single-phase AC voltage output from the portable generator 100, the phase of the reference sine wave is advanced. Can be made closer to the phase of the voltage output by another generator. Also, the first output terminal 15
When the phase of the output current is advanced with respect to the phase of the voltage between the first and second output terminals 152, the phase of the single-phase AC voltage output by the portable generator 100 is delayed by delaying the phase of the reference sine wave. The phase of the voltage output by another generator can be approximated.

Since this phase adjustment changes the number of pulses of the clock signal so as to increase or decrease one pulse every several hundred pulses, one pulse is added every 250 pulses or 300 or more pulses. Alternatively, by performing the subtraction, the phase adjustment can be performed while limiting the fluctuation width to 0.2 Hertz or less at the frequency of 50 Hertz or 60 Hertz specified as the commercial power supply.

When a voltage control type oscillation circuit is used as the oscillation circuit 271 of the sine wave generation circuit 270, the frequency of the high frequency signal output from the oscillation circuit 271 may be adjusted by a phase adjustment signal. is there. The overload detection circuit 269, to which the current detection signal output from the output current detection circuit 330 is input, is based on the current detection signal output from the output current detection circuit 330. Is output, and when the rated current is slightly exceeded, time integration is performed and a stop signal is output after the required time. This stop signal is input to the voltage control circuit 240 and the inverter drive circuit 255, and the voltage control circuit 240
Cuts off the gate current output by the DC voltage generation circuit 110
Stop the operation of the inverter drive circuit 255
In this case, the output of the first PWM signal and the second PWM signal output by the controller is stopped, and the operation of the inverter circuit 130 is also stopped.

Further, the limit value detection circuit 299 to which the current detection signal output from the output current detection circuit 330 is input is a circuit in which a current upper limit value and a current lower limit value are set.
When the current value of the current detection signal becomes equal to or less than the current lower limit value, the peak value (amplitude) of the reference sine wave is reduced or increased so that the output voltage which is the voltage between the first output terminal 151 and the second output terminal 152 is slightly increased. Voltage adjustment circuit to increase the voltage adjustment signal
Output to 277. When the current value of the current detection signal exceeds the current upper limit value, the first output terminal 151 and the second output terminal 1
A voltage adjustment signal for increasing or decreasing the peak value of the reference sine wave so as to slightly reduce the output voltage which is a voltage between 52 is output to the voltage adjustment circuit 277.

As described above, since the current upper limit value and the current lower limit value are set within the range of the rated current and the output voltage can be finely adjusted, the load sharing can be performed while the generators are operating in parallel. If the load is small, the output voltage may be increased slightly to increase the output current, and if the current supplied to the load is near the limit of the rated current, the output voltage may be decreased slightly to reduce load sharing. This makes it possible to efficiently share the load in accordance with the capacity of each portable generator 100 performing the parallel operation.

Therefore, the portable generator as an AC power supply device capable of performing the parallel operation increases the power supply capacity by a plurality of generators even if the generator is a small generator that can be moved. It is possible to cope with a large load such as a large number of loads.

[0043]

The portable generator capable of parallel operation has an advantage that a plurality of generators can cope with a large load. However, as described above, the portable generator capable of parallel operation controls the voltage between the output terminals and the output current from the output terminal when controlling the phase together with the voltage value of the single-phase AC power output from the output terminal. The output is detected and the output adjustment is controlled based on the phase difference between the output voltage and the output current.

For this reason, when a capacitive load or an inductive load is connected, or when a variable load such as a step motor is connected, the phases of the output current and the output voltage are connected in parallel. In addition to being affected by the characteristics of the load as well as the relationship with the set generator, it may be difficult to reduce the phase difference between the generators operating in parallel.

Therefore, a circulating current flows between the generators operating in parallel, and the power generation capacity of the power source cannot be used effectively, and the output of the engine is wasted. The present invention eliminates such disadvantages and ensures that the phase of the single-phase AC voltage output by the portable generator as its own AC power supply matches the phase of the AC voltage output by another AC power supply. It is possible to provide an AC power supply device capable of performing the above.

[0046]

SUMMARY OF THE INVENTION The present invention provides an AC power supply for converting a DC power supply into an AC power supply having a predetermined frequency via an inverter circuit (130) and supplying AC power from an AC output terminal (151, 152) to a load. In the inverter circuit (13
0), the voltage of the AC output terminal (151, 152) at the zero cross point of the AC voltage generated through the AC output terminal is detected, and the AC output terminal (151, 152) at the zero cross point of the AC voltage is detected.
Phase difference between the AC output of the other AC power supply that is operated based on the voltage of the AC power supply and the AC output of the own AC power supply, and detects the AC of the own AC power supply based on the detected phase shift. An AC power supply device having a synchronous operation control unit that adjusts the phase of the output during parallel operation by adjusting the output phase.

As described above, the voltage of the AC output terminals (151, 152) at the zero cross point of the AC power generated through the inverter circuit (130) is detected, and the voltage of the AC output terminals (151, 152) at the zero cross point of the AC power is detected. Since the configuration is such that the phase difference between the AC output of another AC power supply device that is operated in parallel based on the voltage and the AC output of the own AC power supply device is detected, the voltage of the AC output terminals (151, 152) is detected. Only by itself, it is possible to accurately detect a difference between the AC output phase of the own AC power supply device and the AC phase of another AC power supply device, and correct the phase difference.

Therefore, the AC power supply according to the present invention detects a deviation between the AC output phase of its own AC power supply and the AC output phase of another AC power supply based only on the voltage of the AC output terminals (151, 152). Therefore, the circuit configuration and processing means can be simplified. Further, the present invention operates by connecting a portable generator (100) for converting a DC voltage to a single-phase AC voltage by PWM control using an inverter circuit (130) in parallel with another single-phase AC generator. PWM for controlling the inverter circuit (130) when generating power
The timing of the zero-cross point of the sine wave waveform formed by the control signal is compared with the timing of the zero-cross point in the waveform of the voltage between the output terminals (151, 152) of the portable generator (100). This is a synchronous operation method of an AC generator in which a shift between both zero cross points is reduced by adjusting an interval between clock pulses forming a control signal.

As described above, in order to compare the zero-cross point of the sinusoidal waveform formed by the PWM control signal with the zero-cross point of the voltage between the output terminals (151, 152), the portable generator (100) is output by the PWM control signal. Phase comparison with the combined voltage formed by another generator or the like connected to the portable generator (100) can be accurately performed at the zero-cross point, and the other generator and the AC generator ( 100) can be accurately detected.

In correcting the voltage phase shift with respect to another generator, the interval of the clock pulse is finely adjusted to adjust the PWM.
In order to extend or shorten the cycle of the sine wave waveform formed by the control signal to correct the zero-cross point, the portable generator (1
The phase adjustment can be performed while reducing the distortion rate of the single-phase alternating-current voltage output by (00). And as the present invention,
In adjusting the interval of the clock pulse, a slightly wider clock pulse or a slightly narrower clock pulse is used as one of the sinusoidal waveforms formed by the PWM control signal.
A synchronous operation method of an AC generator for adjusting a phase of a sinusoidal waveform formed by a plurality of PWM control signals formed in a cycle.

As described above, the formation of the clock pulse in which the interval of the clock pulse is slightly widened or narrowed can be easily performed by combining the frequency dividing circuit, and the portable generator (100) outputs the clock pulse. Adjustment with the output voltage phase of another generator can be performed while reducing the distortion rate of the single-phase AC voltage. Further, according to the present invention, the amount of change in the interval of one clock pulse is a constant value of about several percent to ten percent, and the difference between the zero cross point of the sine wave waveform formed by the PWM control signal and the zero cross point of the voltage between the output terminals is determined. If the number of pulses exceeds a predetermined set value of about 10, the number of pulses whose pulse interval is changed is set to a sine wave generated by the PWM control signal. A sine wave formed within one cycle of the waveform and formed by changing the pulse interval by the calculated number of pulses within one cycle when the calculated number of pulses is less than the number of set values and forming the PWM control signal There is a case where a synchronous operation method of an AC generator for adjusting a phase of a waveform is used.

As described above, by calculating the number of clock pulses required to correct the deviation and determining the maximum number in one cycle, the maximum frequency variation is regulated to perform the quick correction. In addition to the above, accurate fine adjustment can be performed to minimize the phase shift.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A portable generator according to the present invention rotates an AC generator by an engine having an output of several kilowatts to about 10 kilowatts, temporarily converts the three-phase output voltage of the AC generator to DC, It is a small power supply device that forms a single-phase AC output voltage by being converted into an AC by a circuit, which is frequently moved and used at a place of use, and is sometimes brought into a place of use and operated as a fixed installation state. .

This portable generator as an AC power supply device has an AC generator 50 for rotating a rotor by an engine. As shown in FIG. 1, a DC voltage generation circuit 110, a DC power supply section 120, and an inverter circuit are provided. Power circuit 10 mainly composed of 130
Central control means for setting the frequency of the output voltage output from the output terminal of the power circuit 101, and controlling the entire portable generator 100 based on a detection signal from a detection circuit provided in each unit The portable generator 100 has a microcomputer as 310 and a control power supply unit 201 for generating operating power for the control means and the detection circuit.

The central control means 310 includes a setting switch 318
By setting the frequency of the output voltage to a predetermined constant frequency such as 50 Hz or 60 Hz, based on detection signals from the DC voltage detection circuit 320, the output current detection circuit 330, and the output voltage detection circuit 340 provided in the power circuit 101. In addition, it controls the operation of the inverter circuit 130, and further controls the opening and closing of the engine throttle based on the detection signal from the rotation speed detection circuit 319 and the opening signal from the throttle control mechanism 315.

The setting switch 318 is capable of adjusting the output voltage in addition to setting the frequency. The AC generator 50 of this portable generator 100 has a three-phase output winding 51 and a single-phase output winding 55, the three-phase output winding 51 is in the power circuit 101, and the single-phase output winding 55 is It is connected to the control power supply unit 201.

The output terminal of the three-phase output winding 51 is connected to a DC voltage generating circuit 110 by a rectifying bridge using three rectifying diodes 115 and three thyristors 111, as shown in FIG. Connect and gate voltage generator 1
60 is also connected. This DC voltage generating circuit 110 connects the connection point between the cathode of each rectifier diode 115 and the anode of each thyristor 111 to each output terminal of the three-phase output winding 51, and collects the anodes of each rectifier diode 115. To the negative terminal of the DC power supply unit 120 and the inverter circuit 130, and collectively connect the cathodes of the thyristors 111 to the DC power supply unit 1.
It is connected to the + terminal of 20 and the inverter circuit 130.

The gate voltage generating circuit 160 connected to the output terminal of the three-phase output winding 51 is formed using a rectifying diode, a limiting resistor, a power supply capacitor and a zener diode. That is, each output terminal of the three-phase output winding 51 is connected to the anode of the rectifying diode 161 and the cathode of each rectifying diode 161 is shared.
A negative terminal of the power supply capacitor 165 is connected to the + terminal of the DC power supply unit 120 via a 63, and a zener diode 167 is connected in parallel with the power supply capacitor 165.

Therefore, the gate voltage generation circuit 160
A voltage higher than the voltage of the + terminal of the DC power supply unit 120 by the specified voltage of the Zener diode 167 can be formed and output. The output terminal of the gate voltage generation circuit 160 is connected to each gate terminal of each thyristor 111 in the DC voltage generation circuit 110 via the thyristor control circuit 170.

This thyristor control circuit 170 comprises a switching transistor 173, a switch control resistor 171 and a photocoupler 175. That is, the collector of the PNP transistor serving as the switching transistor 173 is connected to the output terminal of the gate voltage generating circuit 160, and the emitter of the switching transistor 173 is connected to the gate terminal of each thyristor 111. The thyristor 111
When connecting to the gate terminal, the protective resistor 117 is used to connect to the gate terminal.

The base of the switching transistor 173 is connected to the output terminal of the gate voltage generating circuit 160 via the switch control resistor 171, and the switch control resistor 1
The midpoint of 71 is connected to the + terminal of the DC power supply unit 120 via the phototransistor 176 of the photocoupler 175. still,
The phototransistor 176 of the photocoupler 175 has a collector connected to the middle point of the switch control resistor 171, an emitter connected to the + terminal of the DC power supply unit 120, and a light emitting diode 177 of the photocoupler 175 having the anode connected to the control power supply. The cathode of the light emitting diode 177 is connected to the output terminal of the second control voltage Vcc in the unit 201, and the constant voltage detection circuit 180 and the stop circuit 36
0, connected to overcurrent detection circuit 350.

Therefore, the thyristor control circuit 170
When the light emitting diode 177 of the photocoupler 175 turns on,
The phototransistor 176 becomes conductive, the midpoint potential of the switch control resistor 171 drops to the + terminal voltage of the DC power supply unit 120, and the switching transistor 173 becomes nonconductive. When the light-emitting diode 177 does not light, the switching transistor 173 is turned on to supply the output current of the gate voltage generation circuit 160 to each thyristor 111 as the gate current of the thyristor 111. Each thyristor 111 of the generation circuit 110 is turned on.

Therefore, the output power of the three-phase output winding 51 can be supplied to the DC power supply unit 120 connected to both output terminals of the DC voltage generation circuit 110. Also, DC voltage generation circuit
The inverter circuit 130 connected to both output terminals of the 110 is a bridge circuit with a power transistor and a smoothing capacitor.
173. This inverter circuit 130 has a first
The transistor 131 and the third transistor 133 are connected in series to the DC power supply unit 120, and the second transistor 132 and the fourth transistor 134 are connected in series to the DC power supply unit 120, and the first transistor 131 and the third transistor The midpoint of 133 is connected to a first output terminal 151 via a low-pass filter 140,
The midpoint between the second transistor 132 and the fourth transistor 134 is connected to the second output terminal 152 via the low pass filter 140.

The single-phase output winding 55 of the AC generator 50 is connected to the smoothing circuit 210 of the control power supply section 201 as shown in FIG. The smoothing circuit 210 includes four rectifying diodes 2
The bridge rectifier circuit 11 performs full-wave rectification to charge the smoothing capacitor 215. The control power supply unit 201 has a first constant voltage circuit 221 and a second constant voltage circuit 225 and a regulator 230 in addition to the smoothing circuit 210, and the output voltage of the smoothing circuit 210 is adjusted to 15 volts by the first constant voltage circuit 221. And the first reverse current blocking diode 233
To the regulator 230 through the DC power supply unit 120
Is set to a constant voltage of about 12 volts by the second constant voltage circuit 225, and the second reverse current blocking diode 234
Is applied to the regulator 230.

In the regulator 230, a first control voltage Vss of about 10 volts and a second control voltage Vcc of about 5 volts are formed, and the first control voltage Vss is used to drive a throttle control motor for an engine, which will be described later. And the second control voltage Vcc is supplied to the central control means 310 and other control circuit elements. It should be noted that the control power supply unit 201 normally outputs the smoothing circuit 21 from the AC voltage output from the single-phase output winding 55.
The 0 and the DC voltage formed by the first constant voltage circuit 221 are supplied to the regulator 230, and the regulator 230 forms the first control voltage Vss and the second control voltage Vcc and supplies them to each circuit element. Then, when a failure such as a disconnection occurs in the single-phase output winding 55 or the like, if the DC power supply unit 120 is operating, power is supplied to the regulator 230 by the second constant voltage circuit 225,
The first control voltage Vss and the second control voltage Vcc are output from the regulator 230, and the operation of the portable generator 100 is maintained.

A switch circuit for detecting and switching the output voltage of the first constant voltage circuit 221 may be disposed on the input side of the regulator 230 in place of the first backflow prevention diode 233 and the second backflow prevention diode 234. is there. In this case, the output voltage of the first constant voltage circuit 221 and the second constant voltage circuit 225
The power from the first constant voltage circuit 221 is normally supplied to the regulator 230 while the output voltage of the second constant voltage circuit 221 is stopped, and the output voltage from the second constant voltage circuit 225 is stopped when the output of the first constant voltage circuit 221 stops. The switch circuit may be switched so as to supply the voltage to the regulator 230. Further, the AC generator 50 having no single-phase output winding 55 is used, and the smoothing circuit 210 and the first
In some cases, the constant voltage circuit 221 is omitted, the voltage of the DC power supply unit 120 is reduced by the second constant voltage circuit 225, and the power of the DC power supply unit 120 is always supplied to the regulator 230 to form a control voltage.

As shown in FIG. 3, the constant voltage detection circuit 180 for controlling the voltage of the DC power supply unit 120 uses a resistor, a Zener diode, and a switching transistor.
The voltage of the DC power supply unit 120 is divided by the voltage dividing resistors 181 and 182 in which two resistors are connected in series, and the midpoint potential of the voltage dividing resistors 181 and 182 is further reduced by the Zener diode 183 and the detection resistor 184 to detect the voltage. Schmitt circuit 1 for the potential of resistor 184
85, which controls the conduction of the switching transistor 187.

Further, the switching transistor 187
Is connected in series with the light-emitting diode 177 of the photocoupler 175 in the thyristor control circuit 170, and controls the lighting of the light-emitting diode 177 by applying a second control voltage Vcc to the series-connected light-emitting diode 177 and cutting off the conduction of the switching transistor 187. . Therefore, this constant voltage detection circuit 180
Is the detection resistor 1 when the output voltage of the DC power supply 120 rises.
The detection potential of 84 rises and the switching transistor 187
Is turned on to light the light emitting diode 177. For this reason, the thyristor control circuit 170 stops outputting the conduction signal to the DC voltage generation circuit 110, puts each thyristor 111 of the DC voltage generation circuit 110 into a non-conduction state, and outputs the power from the AC generator 50 to the DC power supply unit 120. Stop supply.

When the voltage of the DC power supply 120 drops, the switching transistor 187 is turned off, and a continuity signal is output from the thyristor control circuit 170 to turn on each thyristor 111 of the DC voltage generation circuit 110. In this manner, the potential of the DC power supply unit 120 can be always kept constant by the constant voltage detection circuit 180.

The DC voltage detecting circuit 320 connects the voltage dividing resistor 325 so as to be inserted between both terminals of the DC power supply section 120. The output of the DC power supply section 120 is controlled by the voltage dividing resistor 325. The voltage is divided and the output voltage value of the DC power supply unit 120 is input to the central control means 310 as a DC voltage signal. An output voltage detection circuit 340 inserted between the inverter circuit 130 and the low-pass filter 140 detects the voltage by dividing the first output voltage and the second output voltage of the inverter circuit 130 by a voltage-dividing resistor. A first detection voltage obtained by dividing the first output voltage by the voltage dividing resistors 341 and 342, and a second detection voltage obtained by dividing the second output voltage by the voltage dividing resistors 343 and 344, respectively. The output voltage signal is input to the central control unit 310 via the low-pass filters 347 and 348 for detection.

When the output voltage signal output from the output voltage detection circuit 340 is input to the central control means 310, the first output voltage signal and the second output voltage signal which are analog signals are input to the central control means 310. At the same time, the zero cross signal from the square wave forming circuit 317 is also input to the central control means 310. The rectangular wave forming circuit 317 forms a rectangular wave based on the difference voltage between the first output voltage and the second output voltage forming a sine wave, and generates a square wave based on the difference between the first output voltage and the second output voltage forming a sine wave. The zero cross point in the difference voltage is defined as the edge of this rectangular wave, and a zero cross signal indicating the timing of the zero cross point in the output voltage output from the portable generator 100 is input to the central control means 310.

Further, the output current detection circuit 330 detects the current flowing from the inverter circuit 130 to the low-pass filter 140 with the detection resistor 331 and uses the detection low-pass filter 335 to remove the harmonic component from the output current signal. It is input to the central control means 310 and the overcurrent detection circuit 350. The output current detection circuit 330 may be provided on the input side of the inverter circuit 130. When the output current detection circuit 330 is provided on the input side of the inverter circuit 130,
Output current detection circuit 330 between the side terminal and the inverter circuit 130.
Is provided, it becomes easy to lower the absolute voltage of the output current signal output from the output current detection circuit 330.

As the output current detection circuit 330, not only the case where the detection resistor 331 is used, but also a current detector using an induction coil or the like may be used. The overcurrent detection circuit 350 includes resistors 351 and 352, a comparator 355, and a switching transistor 357, and applies the second control voltage Vcc formed by the control power supply unit 201 to the reference voltage dividing resistors 351 and 352.
The reference voltage is formed by voltage division by 352, and when the potential of the output current signal output from the output current detection circuit 330 becomes higher than the reference voltage, the switching transistor 357 is turned on.

Further, the switching transistor 357
Has an emitter grounded and a collector connected to the cathode of the light emitting diode 177 in the photocoupler 175. Therefore, when the switching transistor 357 is turned on, the overcurrent detection circuit 350
To stop the output of the conduction signal. The central control means 310
The DC voltage signal from the DC voltage detection circuit 320, the output current signal from the output current detection circuit 330, and the output voltage signal from the output voltage detection circuit 340 and the square wave forming circuit 317 based on this output voltage signal Is input as a detection signal, a detection signal of the frequency of the output voltage output from the three-phase output winding 51 is also input as a rotation speed signal from the rotation speed detection circuit 319, and the cathode potential of the light emitting diode 177 is also detected. Is also input as a conductivity detection signal, and a throttle opening signal is also input from the throttle control mechanism 315, but the opening signal from the throttle control mechanism 315 can be omitted.

The central control means 310 to which these detection signals are input operates as shown in FIG.
In addition to the PWM signal generation section 441 for outputting a control signal to the PWM driver, the output voltage signal from the output voltage detection circuit 340 and the zero-cross signal from the rectangular wave formation circuit 317 determine whether control is started alone or in parallel at the start of control. Single operation control unit 435 and synchronous operation control unit that control signal generation unit 441
437, an output voltage setting unit 417 that adjusts and sets the output voltage of the single-phase AC voltage by a signal from the setting switch 318, an output frequency setting unit 415 that sets the frequency of the single-phase AC voltage by a signal from the setting switch 318, and A voltage waveform monitoring unit 433 that monitors a single-phase AC voltage output from the first output terminal 151 and the second output terminal 152 based on an output voltage signal from the output voltage detection circuit 340, and a rotation speed from the rotation speed detection circuit 319. An engine speed detector 421 for judging the engine speed by a signal, a throttle opening controller for outputting a rotation control signal to a throttle driver 313 based on an output current signal, an engine speed signal and an opening signal from a throttle control mechanism 315. 423, and outputs a stop control signal to the stop circuit 360 based on the output current signal from the output current detection circuit 330 and the DC voltage signal from the DC voltage detection circuit 230. Protection unit 4
31, light emitting diode 177 in thyristor control circuit 170
A conductivity detection unit 419 for detecting the conductivity of the thyristor 111 in the DC voltage generation circuit 110 based on the cathode potential of the DC voltage generation circuit 110, and further displays the operation status of the portable generator 100 in accordance with the control operation status of the central control means 310. A display control unit 425 for outputting a signal to be displayed on the display unit 427 is formed.

The central control means 310, which is a microcomputer, has a crystal oscillator (not shown) operating at a frequency of ten and several megahertz, operates using the output of the crystal oscillator as a reference clock, and executes a control program or control program. It has a read only memory in which a data table and the like are recorded, a random access memory for performing arithmetic processing, and a frequency dividing circuit for dividing a reference clock to form a required clock signal. An analog-to-digital converter 41 for converting an input analog signal into a digital signal.
It also has one.

When the throttle control mechanism 315 controls the rotation of the throttle valve by using a pulse motor, a pulse counter is built in the throttle opening control section 423, and the throttle opening control section 423 outputs to the throttle driver 313. The throttle value may be counted up or down according to the rotation control signal, and the throttle opening control unit 423 may store the throttle opening by omitting the opening signal from the throttle control mechanism 315.

Then, the PWM signal generation section 441 outputs the PWM
It has a reference table, and outputs a PWM control signal to the PWM driver 311 based on the PWM reference table.
The conduction and cutoff of each transistor as the transistor 134 is controlled. This PWM reference table is a table that stores a large number of PWM reference values, and each PWM reference value is a numerical value of about one hundred to several hundreds corresponding to a value of a curve forming one cycle of a sine wave curve. .

Then, the PWM signal generator 441 of the central control means 310 sequentially reads out the PWM reference values from the PWM reference table at a constant cycle to form a PWM control signal, and outputs the PWM control signal to the PWM driver 311. I do. When the head value of the PWM reference table is 0, the PWM control signal adds a value corresponding to a half of one clock time in a read clock for reading the PWM reference value to each of the read PWM reference values. When the reference value is 0, a pulse signal having a duty ratio of 50% is formed. For this reason, as shown in FIG. 5A, each pulse of the PWM control signal sequentially changes the duty ratio in accordance with the sinusoidal wave shape, and the duty ratio is several tens to 100% around 50%. Is a signal train of pulse signals having a pulse width value forming a reference sine wave shape that sequentially changes with a value in the range up to several tens of percent before.

Then, the PWM driver 311
A first PWM signal, which is obtained by amplifying the current of the WM control signal and outputting it to the first transistor 131 and the fourth transistor 134, and a second transistor 132 which inverts and amplifies the PWM control signal.
And a second PWM signal to be output to the third transistor 133, and outputs the first PWM signal and the second PWM signal to the inverter circuit 130.

Further, the voltage waveform monitor 4 of the central control means 310
Reference numeral 33 denotes an output voltage value table for storing a number of voltage table values corresponding to each PWM reference value. The output voltage value table is read from the voltage table value in accordance with the timing at which the PWM reference value is read from the PWM reference table. And compares the read voltage table value with the value of the output voltage input from the output voltage detection circuit 340 to obtain the PWM value.
The pulse width of each pulse signal forming the PWM control signal output from the signal generation unit 441 is corrected to adjust the output voltage.

When the required time has elapsed from the start of rotation of the engine and the output of the single-phase AC voltage is started, or when an output switch (not shown) is operated, the PWM control signal is output from the PWM signal generation section 441. When starting the output of the single-phase AC voltage from the first output terminal 151 and the second output terminal 152, the central control means 310 determines whether or not the zero-cross signal from the rectangular wave forming circuit 317 is input. , When the zero cross signal is not input,
Start operation of 435.

When the operation of the isolated operation control section 435 is started, the PWM signal generation section 441 of the central control means 310 is started.
Is an average output voltage between the first output terminal 151 and the second output terminal 152, such as 100 volts set by the setting switch 318, and a sine wave voltage of 50 Hz or 60 Hz which is the set frequency. Is output.

The frequency of the output voltage, which is the voltage between the first output terminal 151 and the second output terminal 152, corresponds to one cycle of the single-phase AC voltage recorded in the PWM reference table of the PWM signal generator 441. 100 to several hundred PWMs forming
The frequency of the single-phase AC voltage output from the portable generator 100 is determined by selecting a clock signal for reading the reference value in 20 ms or selecting a clock signal for reading in 16.66 ms. .

The output voltage is set by multiplying a PWM reference value recorded in a PWM reference table by a correction value to form a corrected reference value, and based on the corrected reference value, a pulse signal serving as a PWM control signal. Are determined. Then, the independent operation control unit 435 reads the correction value for calculating the correction reference value from the PWM reference value from the output voltage setting unit 417, and transfers the correction value to the PWM signal generation unit 441.

Further, after the PWM control signal is output from the PWM signal generation unit 441, the peak voltage and the sine wave distortion are monitored by the output voltage waveform monitoring unit 433 based on the output voltage signal from the output voltage detection circuit 340. When the peak voltage fluctuates from the set value, a correction value for correcting the difference from the set voltage is read from the output voltage waveform monitoring unit 433 to the PWM signal generation unit 441. Further, even when the distortion of the sine wave continues, the correction value is read by the PWM signal generation unit 441 so that the single-phase AC voltage which is a set voltage and is a smooth sine wave is always output. I have.

In the case of independent operation, a pulse signal having a duty ratio of 50% is output from the central control means 310 as a PWM control signal. Control means
The minute time before input to 310 is determined by the inverter circuit 130
Although the voltage table value is preset and compared with the detected output voltage value by such circuit characteristics as described above, this minute time difference is corrected based on the zero cross signal input from the rectangular wave forming circuit 317, and PWM control is performed. In some cases, the relationship between the signal and the output voltage output to the first output terminal 151 and the second output terminal 152 may be correctly adjusted.

When starting the output of the PWM control signal from the PWM signal generation section 441, when the zero-cross signal is input from the rectangular wave forming circuit 317 to the central control means 310, the central control means 310 controls the synchronous operation control. The operation of the unit 437 is started. The synchronous operation control unit 437 determines whether the frequency of the voltage generated between the first output terminal 151 and the second output terminal 152 matches the frequency set by the setting switch 318 according to the input interval of the zero cross signal. Is determined first.

If the frequencies match, it is determined based on the output voltage signal whether or not the peak voltage is substantially equal to the peak value of the voltage set by the setting switch 318. In this way, when the voltage generated between the first output terminal 151 and the second output terminal 152 is compared with the frequency and voltage set by the setting switch 318, and it is determined that they do not match the set values. Outputs an abnormal signal to the display control unit 425 without starting the operation of the PWM signal generation unit 441, and causes the display control unit 425 to output a required display signal to the operation state display unit 427.

When the frequency and the voltage match the set values, the PWM signal generator 441 starts operating in accordance with the rise of the zero-cross signal from the rectangular wave forming circuit 317, and the PWM reference table in the PWM reference table is activated. The value is read from the head and the output of the PWM control signal is started. Therefore, the inverter circuit 130 operates and the low-pass filter 140
And the phase and voltage of the single-phase AC voltage are matched with the AC voltage input between the first output terminal 151 and the second output terminal 152 so that the AC power supply The output of the AC voltage can be started from the portable generator 100 as a device.

After starting the synchronous operation in this manner, the synchronous operation control unit 437 sets the central control unit every time the PWM signal generation unit 441 outputs a PWM control signal based on 0 which is the leading value of the PWM reference value. The zero-cross signal input to 310 is determined, and phase adjustment control between the portable generator 100 and another generator is performed. When a PWM control signal based on a PWM reference value is output as shown in (1) of FIG. 5, the single-phase AC voltage, which is an output voltage at the time of the synchronous operation, becomes a sine wave a in FIG. Is output from the low-pass filter 140 having a zero-cross point substantially coincident with 0 of the PWM reference signal. However, the phase of the voltage output from the portable generator 100 via this low-pass filter 140 and the phase of the sine wave voltage output from the other generators are shown in FIG.
5 (c), the voltage generated between the first output terminal 151 and the second output terminal 152 is combined as shown as b in FIG. 5 (3). Voltage. That is, the zero-cross point of the reference sine wave shown in (1) of FIG. 5 becomes a sine wave shown in (2) of FIG. 5 and the zero-cross point of the output voltage signal deviates from the zero-cross point of the reference sine wave. become.

Therefore, the PWM based on the PWM reference value of 0
At the timing when the control signal is output, if the rectangular wave serving as the zero-cross signal of the output voltage is at the L level, the single-phase AC voltage output from the portable generator 100 is output by another generator operating in parallel. The synchronous operation control unit 437 determines that the phase is ahead of the voltage to be synchronized, and performs control to lengthen the cycle of the reference sine wave used as the PWM control signal.

If the rectangular wave serving as the zero cross signal of the output voltage is at the H level at the timing when the PWM control signal based on the PWM reference value of 0 is output, the synchronous operation control unit
437 performs control to shorten the cycle of the reference sine wave. This P
When adjusting the period of the sine wave waveform formed by the WM control signal, the synchronous operation control unit 437 sets the PWM reference value to PWM
This is for changing the interval between clocks read from the M reference table.

This clock interval controls the frequency divider circuit that forms the clock for reading the PWM reference value, and makes the time of one clock (the time interval of one step in the PWM modulation cycle) longer or shorter by several percent to ten percent. Approximately several to ten clock signals out of one hundred to several hundred clocks forming one cycle are formed. As described above, the first sine wave at the timing of the zero-cross point by the PWM control signal generated by the PWM signal
Detects whether the voltage generated between the output terminal 151 and the second output terminal 152 is positive or negative, that is, the shift of the zero cross point between the reference sine wave and the output voltage, and reads and outputs the PWM reference value.
In order to adjust the output timing of the WM control signal, the effect based on the phase difference between the output voltage and the output current depending on the type of load is eliminated, and the phase difference between the output voltage of another generator and the portable generator 100 is accurately determined Can be modified.

In correcting the output timing of the PWM control signal based on the PWM reference value, several to ten pulses are used to change the time interval of one step slightly longer or shorter by about several percent to ten percent. Because the clock signal is formed by only a plurality of
Adjustment can be performed such that the variation rate of one cycle of the sinusoidal waveform formed by the M control signal is about 0.3% or less, and the variation is less than 0.2 Hertz for 50 Hertz or 60 Hertz.

Further, the frequency adjustment of the sine wave waveform by the PWM control signal only slightly changes the interval of the clock signal, that is, the output interval of the PWM control signal by about several percent to ten percent. The number of pulse signals to be transmitted and the value of each PWM control signal, PW
Since the pulse width of each pulse as the M control signal is not changed, the cycle is adjusted while smoothly changing the sine wave waveform formed by the PWM control signal and the waveform of the single-phase AC voltage output from the portable generator 100. can do.

In forming several to ten clock pulses in which the clock pulse interval is changed by several percent to ten percent, the clock pulse in which the clock pulse interval is changed may be formed continuously. . Further, the clock pulses whose clock pulse intervals are changed may be dispersed within one cycle of the reference sine wave, and the pulse interval may be changed for a required number of clock pulses formed during one cycle. .

As described above, by dispersing the clock pulses whose clock pulse intervals are changed, the sinusoidal waveform formed by the PWM control signal, and furthermore, the waveform distortion of the single-phase AC voltage is reduced, and the smoother sinusoidal waveform is formed. The phase can be adjusted while maintaining the output. Further, when the timing of the zero-cross signal formed from the output voltage signal has a deviation of not less than a fixed value of about 3 milliseconds from the timing of the zero-cross of the sine wave waveform, the number is set to about several to ten in one cycle. If the difference between the timing of the zero-cross signal and the zero-cross of the sine wave waveform is less than or equal to a certain value, the pulse signal that is changed to be longer or shorter by a certain interval will be changed. In some cases, the number of pulses required to correct the amount is calculated, and a clock signal that changes the pulse interval by the calculated number of pulse signals may be formed.

As described above, by calculating the number of clock pulses for changing the interval by detecting the amount of deviation, the output voltage of the portable generator 100 can be more accurately converted to the voltage of another generator operating in parallel. Control that matches the phase can be performed. Then, as described above, the PWM signal generation unit 441 has an output voltage value table, compares the voltage table value read from the output voltage value table with the output voltage read by the output voltage signal, and generates a PWM control signal. Even if the pulse width of the pulse signal to be formed is corrected, when the value of the output voltage detected during the synchronous operation becomes larger than the voltage table value,
Correction to increase the pulse width of the PWM control signal is performed in accordance with the amount of change.

In the case of isolated operation, a correction is made to decrease the output voltage by decreasing the pulse width of the PWM control signal. As described above, when the output voltage increases during the synchronous operation, the pulse width of the pulse signal serving as the PWM control signal is increased to output the signal via the inverter circuit 130 and the low-pass filter 140 of the portable generator 100. By increasing the value of the single-phase AC voltage, it is possible to follow a change in the voltage output from another generator operating in parallel.

The synchronous operation control section 437 adjusts the peak voltage of the reference sine wave, that is, the value of the pulse width of the PWM control signal, based on the output current value from the output current detection circuit 330 to adjust the output voltage. Also do. The adjustment of the output voltage is performed when the current value output from the first output terminal 151 or the second output terminal 152 by the output current signal is 85% of the rated current value.
When the value exceeds a predetermined value of percent to 90 percent, the pulse width of the pulse signal used as the PWM control signal is slightly reduced so as to reduce the value of the single-phase AC voltage by about 1 percent.

As described above, when the output current value becomes close to the rated current value, the output voltage is slightly reduced, so that the load sharing of the generators operating in parallel operation is assigned to one of the generators. It can be prevented from being too lean. Further, the central control unit 310 controls the DC voltage generation circuit 110 by the circuit protection unit 431, and controls the engine speed by the throttle opening control unit 423.

The control of the DC voltage generation circuit 110 by the circuit protection section 431 is performed by the stop circuit 360 via the thyristor control circuit 170 as shown in FIG. The stop circuit 360 includes a switching transistor 361 whose base is connected to the central control means 310, an emitter of the switching transistor 361 is grounded, and a collector of the switching transistor 361 is connected to a cathode of the light emitting diode 177 in the photocoupler 175. Is what it is.

[0104] The DC voltage generating circuit 110 is
When the engine is started, the stop control signal is output from the circuit protection unit 431 until the engine speed signal input from the engine speed detection circuit 319 is stably maintained.
60 to turn on the light emitting diode 177 so that the thyristor control circuit 170 does not output a conduction signal.

When the engine speed is stabilized, the output of the stop control signal is stopped, and the DC voltage detection circuit 32
The voltage of the DC power supply unit 120 becomes 16
After confirming that the voltage reaches a predetermined voltage of 0 to 200 volts, the isolated operation control unit 435 or the synchronous operation control unit 437
, The output of the PWM control signal from the PWM signal generation unit 441 is started.

Further, the engine is controlled by rotating the pulse motor of the throttle control mechanism 315 forward or reverse through the throttle driver 313 by the engine speed detector 421 and the throttle opening controller 423. This engine speed control is performed by the output current detection circuit 330.
Throttle control mechanism 315 in accordance with the output current signal from
Or a predetermined value, or the count value of the pulse counter of the throttle control mechanism 315 is set to a predetermined value, and the predetermined engine speed is adjusted according to the output. Further, the ratio of the time during which the conduction signal is output to the DC voltage generation circuit 110 by the cathode potential of the light emitting diode 177 in the photocoupler 175, that is, the thyristor 111
High-efficiency voltage conversion by correcting the throttle opening according to the conductivity of the throttle.

Further, in this portable generator 100, when an overcurrent exceeding the rated current flows, control for stopping the operation of the DC voltage generation circuit 110 and the inverter circuit 130 is performed by the circuit protection unit 431 of the central control means 310. In addition, the power circuit 101 is protected by stopping the output of the single-phase AC voltage, and the control of stopping the operation of the DC voltage generation circuit 110 by the overcurrent detection circuit 350 is performed.

Circuit protection section 431 for protecting power circuit 101
When the output current value exceeds 1.2 times the rated voltage, PW is applied after a duration of several seconds to several minutes.
The output of the PWM control signal output from the M signal generation unit 441 is stopped, and the output of the stop control signal to the stop circuit 360 is started. When the output current value is large according to a value exceeding 1.2 times the rated current, the output of the stop control signal is started in a short duration and the output of the PWM control signal is stopped by the PWM signal generation unit 441. When the value exceeding the rated current is small, the output of the stop control signal and the output stop of the PWM control signal are controlled for a somewhat longer duration to stop the output of the single-phase AC voltage. When the value of the output current reaches more than twice the rated voltage, the output of the PWM control signal is immediately stopped, and the output of the stop control signal is started to stop the output of the single-phase AC voltage.

Further, when the value of the DC voltage detected by the DC voltage detection circuit 320 or the value of the output voltage detected by the output voltage detection circuit 340 becomes abnormally high, the output voltage is the set value. For example, the circuit protection unit 431 sends a stop control signal to the stop circuit 360 when detecting that an abnormal voltage has occurred in the power circuit 101, such as when the voltage drops significantly above 100 volts or when a voltage lower than 100 volts continues. Then, the output of the single-phase AC voltage from the first output terminal 151 and the second output terminal 152 is stopped by causing the PWM signal generation unit 441 to stop outputting the PWM control signal.

The overcurrent detection circuit 350 provided separately from the central control means 310 outputs an L level stop signal to the photocoupler 175 when the value of the output current reaches nearly twice the rated voltage. Then, the output of the conduction signal output from the thyristor control circuit 170 to the DC voltage generation circuit 110 is stopped.
For this reason, when the value of the output current reaches nearly twice the rated voltage, each thyristor 111 of the DC voltage generation circuit 110 is turned off, and the power supply from the AC generator 50 to the DC power supply unit 120 is performed. Is stopped. Therefore, the output voltage of DC power supply unit 120 drops.

Therefore, the output voltage of DC power supply
A first PWM signal and a second PWM signal based on a PWM control signal having a constant duty ratio and an AC voltage by the M control.
The output voltage, which is the potential difference between the first output terminal 151 and the second output terminal 152 formed by the WM signal, decreases, the load current also decreases, and the output current exceeds twice the rated current and the single-phase AC voltage immediately. Can be prevented from being stopped, and the output of the single-phase AC voltage can be stopped in a very short time because the output current value is much more than 1.2 times the rated current.

For this reason, when the portable generator 100 is operated with a predetermined load connected to it and an additional motor or discharge lamp is operated, the rated current may be greatly exceeded instantaneously. Then, even if a turbulence in which the output voltage drops at this moment occurs, the output of the single-phase AC voltage output from the first output terminal 151 and the second output terminal 152 is maintained, and the load already operating is stopped. Without starting, the additional motor is started or the discharge lamp is turned on, and all the rated loads within the output rated output of the portable generator 100 can be operated.

The overcurrent detection circuit 350 is limited to a case where a reference voltage is set so that a stop signal is output when the output current detection circuit 330 detects a current value nearly twice the rated current value. Without, when a current exceeding 1.5 times the rated current value is about to flow, the rectifying operation of the DC voltage generation circuit 110 is stopped, and the power supply from the AC generator 50 to the DC power supply unit 120 is stopped, For example, when reducing the output voltage, the characteristics and durability of the elements forming the power circuit 101,
In addition, according to the safety standard, the central control means 310 is set as an appropriate value together with the output current value when the stop control signal is output.

In the above embodiment, the PWM reference value for one cycle of the PWM reference value is stored as the PWM reference table, but the PWM reference value for a half cycle or the PWM reference value for a quarter cycle is stored.
The reference value may be stored. As described above, when the PWM reference value for a half cycle or a quarter cycle is stored in the PWM reference table, there is an advantage that the used capacity of the memory is reduced. However, when the PWM reference value for one cycle is stored, there is an advantage that the arithmetic processing for forming the PWM control signal is reduced and the load on the central control unit 310 is reduced.

Further, in the embodiment of the present invention, although the PWM control signal is formed by the PWM signal generating section 441 in the microcomputer, the step-like shape is formed by the multiplexer and the multi-stage voltage dividing resistor as in the conventional case. Even in the case of forming a pseudo sine wave, a plurality of pulses for slightly changing the pulse interval of the clock signal for controlling the switching of the multiplexer are formed in one cycle, and the cycle of the stepped sine wave is changed to thereby form a low-pass filter. It is also possible to adjust the period of the reference sine wave formed via 279.

[0116]

According to the present invention, there is provided an AC power supply device for converting a DC power supply into an AC power supply having a predetermined frequency and supplying the AC power supply from an AC output terminal. Voltage, and detects a phase shift between the AC output of the other AC power supply and the AC output of the own AC power supply based on the voltage of the AC output terminal at the zero cross point of the AC voltage. The AC power supply device includes a synchronous operation control unit that performs phase adjustment during parallel operation by adjusting the phase of the AC output of the own AC power supply device based on the deviation.

Therefore, it is possible to accurately detect the difference between the AC output phase of the own AC power supply device and the AC output phase of another AC power supply device and correct the phase difference only by detecting the voltage. Then, since the deviation can be detected based only on the voltage of the AC output terminal, the circuit configuration and the processing procedure can be simplified. According to another aspect of the present invention, a portable generator for converting a DC voltage into a single-phase AC voltage by PWM control using an inverter circuit and another single-phase AC generator are connected in parallel to operate. At this time, the timing of the zero cross point of the sine wave waveform formed by the PWM control signal is compared with the timing of the zero cross point of the voltage between the output terminals, and the interval between the clock pulses forming the PWM control signal when both zero cross points are shifted. This is a synchronous operation method of the AC generator for finely adjusting.

Therefore, the coincidence or deviation between the phase of the voltage output from the generator and the voltage phase of another generator can be accurately detected based on the PWM control signal, and the output from the generator can be obtained. Synchronous phase adjustment of the generator can be performed while reducing the distortion rate of the single-phase AC voltage. Further, the present invention provides a method for adjusting a clock pulse interval, wherein a clock pulse having a slightly widened interval or a clock pulse having a slightly narrowed interval is formed of a sine wave waveform formed by a PWM control signal. P is formed in one cycle
The synchronous operation method for an AC generator according to claim 2, wherein the phase of a sine wave waveform formed by the WM control signal is adjusted.

Therefore, it is easy to adjust the phase of the generator while reducing the distortion of the output voltage. According to a fourth aspect of the present invention, the amount of change in the interval between one clock pulse is fixed, and the difference between the zero cross point of the sine wave waveform formed by the PWM control signal and the zero cross point of the voltage between the output terminals is corrected. The number of pulses required to perform the calculation is calculated. If the number of pulses exceeds a predetermined set value, the set number of pulses with the changed pulse interval is included in one cycle of the sine wave waveform formed by the PWM control signal. 4. The synchronization of the alternator according to claim 2, wherein when the calculated number of pulses is smaller than the number of set values, a pulse whose pulse interval is changed by the calculated number of pulses is formed in one cycle. It is a driving method.

Therefore, the phase shift can be extremely reduced by performing accurate fine adjustment, and wasteful power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire portable generator according to the present invention.

FIG. 2 is a circuit block diagram mainly showing a power supply unit of the portable generator according to the present invention.

FIG. 3 is a circuit block diagram mainly showing a detection circuit of the portable generator according to the present invention.

FIG. 4 is a block diagram showing an outline of central control means of the portable generator according to the present invention.

FIG. 5 is a graph showing a voltage output state of the portable generator according to the present invention.

FIG. 6 is a circuit block diagram showing an example of a conventional portable generator.

FIG. 7 is a schematic diagram showing an output voltage.

FIG. 8 is a circuit block diagram showing an example of another conventional portable generator.

[Explanation of symbols]

Reference Signs List 50 AC generator 51 Three-phase output winding 55 Single-phase output winding 100 Portable generator 101 Power circuit 110 DC voltage generation circuit 111 Thyristor 115 Rectifier diode 120 DC power supply unit 121 Main smoothing capacitor 130 Inverter circuit 140 Low-pass filter 151 First 1 output terminal 152 second
Output terminal 160 Gate voltage generation circuit 170 Thyristor control circuit 180 Constant voltage detection circuit 201 Control power supply section 210 Smoothing circuit 221 First constant voltage circuit 225 Second
Constant voltage circuit 230 Regulator 235 Constant voltage circuit 240 Voltage control circuit 250 PWM signal generation circuit 255 Inverter drive circuit 260 Overload detection circuit 265 Operation circuit section 269 Overload detection circuit 270 Sine wave generation circuit 281 Triangular wave generation circuit 285 PWM control signal generation Circuit 291 Square wave generation circuit 293 Start timing circuit 295 Square wave generation circuit 297 Phase comparison circuit 299 Limit value detection circuit 310 Central control means 311 PWM driver 313 Throttle driver 315 Throttle control mechanism 317 Speed detection circuit 319 320 DC voltage detection circuit 330 Output current detection circuit 340 Output voltage detection circuit 350 Overcurrent detection circuit 432 Throttle opening control section 431 Circuit protection section 433 Output voltage monitoring section 435 Single operation control section 435 Period operation control unit 441 PW
M signal generator

Claims (4)

[Claims] 1. An AC power supply device for converting a DC power supply into an AC power supply having a predetermined frequency via an inverter circuit and supplying AC power from an AC output terminal to a load, wherein a zero-crossing point of an AC voltage generated via the inverter circuit is provided. At the AC output terminal at the zero-cross point of the AC voltage, and the AC output of the other AC power supply device operated based on the voltage of the AC output terminal at the zero-cross point of the AC voltage and the AC output of the own AC power supply device. A synchronous operation control unit that detects a phase shift and adjusts the phase of the AC output of the own AC power supply device based on the detected phase shift to perform phase adjustment of the AC output during parallel operation is provided. AC power supply device characterized by the above-mentioned. 2. When a portable generator for converting a DC voltage into a single-phase AC voltage by PWM control using an inverter circuit and another single-phase AC generator are connected in parallel and operated,
The timing of the zero-cross point of the sine wave waveform formed by the PWM control signal for controlling the inverter circuit is compared with the timing of the zero-cross point in the waveform of the voltage between the output terminals of the portable generator. A synchronous operation method for an AC generator, characterized in that a shift between two zero-cross points is reduced by finely adjusting an interval between clock pulses forming a PWM control signal. 3. When adjusting the interval between clock pulses, a plurality of clock pulses having a slightly wider interval or a slightly narrower interval are formed in one cycle of a sine wave waveform formed by a PWM control signal. 3. The synchronous operation method for an AC generator according to claim 2, wherein the phase of the sine wave waveform formed by the PWM control signal is adjusted by adjusting the phase. 4. When adjusting the interval between clock pulses, the amount of change in the interval between one clock pulse is set to a constant value of about several percent to about ten percent, and between the zero cross point of the sine wave waveform formed by the PWM control signal and the output terminal. The number of pulses required to correct the difference between the voltage and the zero crossing point is calculated, and when the number of pulses exceeds a predetermined set value of about 10, the set number of pulses whose pulse interval is changed is used. When the calculated number of pulses is less than the number of set values, a pulse whose pulse interval is changed by the calculated number of pulses is formed within one cycle of the sine wave waveform formed by the PWM control signal. 3. The method according to claim 2, wherein
Or the synchronous operation method of the alternator according to claim 3.