JP2571467Y2 - Power supply device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a power supply device, and more particularly to a power supply device of an engine-driven generator for generating a commercial AC voltage using an inverter circuit driven by a pulse width modulation (PWM) control signal. A power supply device in which a resistor is connected between an output terminal and the ground to divide the generated AC voltage, and feedback is performed based on the divided voltage to make the commercial AC voltage a constant voltage. is there.

[0002]

2. Description of the Related Art In a conventional power supply device for an engine-driven generator that generates a commercial AC voltage by using an inverter circuit driven by a PWM control signal, an output detection circuit for making the output voltage constant is shown in FIG. As shown in FIG. 5, a detection transformer 10 was used.

In FIG. 1, reference numerals 1 to 4 denote transistors, 5 and 6 denote inductors, 7 denotes capacitors,
Reference numeral 9 denotes an output terminal. The transistors 1 and 4 and the transistors 2 and 3 form a pair, respectively. When the transistors 1 and 4 forming a pair are first turned on by a PWM control signal from a PWM signal generation circuit (not shown), the transistor 1, the inductor 5, a current flows in the direction of the capacitor 7, the inductor 6, and the transistor 4, and when the paired transistors 2 and 3 are subsequently turned on by the PWM control signal from the PWM signal generation circuit, the transistor 3, A current flows in the direction of the inductor 6, the capacitor 7, the inductor 5, and the transistor 2.

As described above, the transistors 1 and 4 and the transistors 2 and 3 forming a pair are alternately controlled to be turned on, and by passing through a low-pass filter composed of inductors 5 and 6 and a capacitor 7, an output terminal is provided. 8,
A commercial AC voltage is generated during 9.

[0005]

However, when voltage detection is performed using the detection transformer 10 shown in FIG. 5, the output waveform is distorted due to the inductance L of the detection transformer 10, and there is a drawback that the excitation current and the like are reduced. In addition to the large loss, there are disadvantages that the weight is heavy and the cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks. For each output terminal, a resistor is connected between the output terminal and the ground to divide the generated AC voltage. It is an object of the present invention to provide a power supply device for converting a commercial AC voltage to a constant voltage by applying feedback based on the power supply.

[0007]

In order to achieve the above object, a power supply device of the present invention uses a voltage generated from a generator driven by an engine as a drive source and a PWM signal generation circuit (1).
7) The bridge circuit unit (1) including the transistors (1, 2, 3, 4) controlled by the PWM control signal from (1).
4) A power supply device for generating a commercial AC voltage at the output terminals (8, 9), wherein each of the output terminals (8, 9) is connected in series between the output terminal (8, 9) and the ground.
Connected resistors (21, 22) and (23, 24)
And the resistors (21, 22) and (23, 2) connected in series.
4) a detection circuit (15) configured to receive each divided voltage of the AC voltage generated at each series connection point by a differential amplifier (25);
An error signal is obtained from the detection signal detected by the detection circuit (15) and the reference signal to obtain the PWM signal generation circuit (17).
And an error detecting unit (16) for feeding back the feedback.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 11 denotes an engine, 12 denotes a DC generator, 13 denotes a stabilizing circuit, 14 denotes a bridge circuit,
Represents a detection circuit, 16 represents an error detection section, 17 represents a PWM signal generation circuit, and 18 and 19 represent inverters.

The bridge circuit section 14 has the same configuration as that of FIG. 1 except for the detection transformer 10. The bridge circuit section 14 is driven by the engine 11 and converts the DC voltage generated in the DC generator 12 by the stabilization circuit 13. After the stabilization, the DC voltage is supplied to the bridge circuit unit 14 as Vcc.

The detection circuit 15 includes a resistance detection section in which resistances 21 to 24 are connected between the output terminals 8, 9 and the ground for each of the output terminals 8, 9. The resistors 21 and 23 have the same resistance value, and the resistors 22 and 24 have the same resistance value. These resistors 21 to 24 divide the commercial AC voltage generated between the output terminals 8 and 9 with high resistance.

The voltages divided by the resistors 21 and 22 and the resistors 23 and 24 are phase-shifted by a differential amplifier 25. The error detection unit 16 is a circuit unit that compares the detection signal detected by the detection circuit 15 with a reference signal and detects the error.

The PWM signal generating circuit 17 includes an error detecting section 16
Output terminals 8, 9 based on the error signal input from
It outputs a PWM control signal for generating a constant commercial AC voltage at a constant frequency in between. The PWM control signal output from A of the PWM signal generation circuit 17 is, together with the PWM control signal obtained through the inverter 18,
For example, switching control is performed on each of the transistors 1 and 4 forming a pair. The PWM control signal output from B of the PWM signal generating circuit 17 controls the switching of the other pairs of transistors 3 and 2 together with the PWM control signal obtained via the inverter 19.

Error detection unit 16 and PWM signal generation circuit 1
After a more detailed circuit configuration is described for 7, the operation of FIG. 1 will be described. FIG. 2 shows an embodiment of a specific circuit of the present invention.

In the figure, reference numerals 1 to 9 correspond to those in FIG. 5, and 14, 15, 18, 19, 21 to 25 correspond to those in FIG. Reference numeral 26 denotes a sine wave generation circuit, 27
Denotes a triangular wave generating circuit, 28 denotes an error amplifier, 29 and 30 denote comparators, and 31 denotes a switch.

The sine wave generating circuit 26 is a reference signal oscillator for generating a sine wave having a predetermined frequency, that is, a commercial frequency of 50 Hz or 60 Hz by the switch 31, and the output terminals 8 and 9 have the oscillating frequency of the sine wave generating circuit 26. The frequency of the AC voltage generated is determined.

The triangular wave generating circuit 27 is a sine wave generating circuit 26.
And outputs a triangular wave signal X having a higher frequency than the commercial frequency of the reference signal Y generated as shown in FIG. The error amplifier 28 compares the reference signal of the commercial frequency input from the sine wave generation circuit 26 with the detection signal input from the detection circuit 15, and adjusts the error amplifier so that the reference signal and the detection signal become zero. 28 outputs the error signal. That is, in the differential amplifier 25 of the detection circuit 15, the output terminals 8,
An error signal is obtained by adding the signal obtained by inverting the phase of the divided voltage between 9 and the reference signal from the sine wave generation circuit 26.

The comparators 29 and 30 compare the triangular wave signal X from the triangular wave generating circuit 27 with the error signal Y from the error amplifier 28, and according to the magnitude of the triangular wave signal X and the error signal Y as shown in FIG. , The comparator 29 generates a positive PWM control signal, and the comparator 30 generates a negative PWM control signal.

When the commercial AC voltage generated between the output terminals 8 and 9 fluctuates from a predetermined rated voltage due to rotation fluctuation of the engine 11, connection of a load, or the like, a detection circuit 15 detects a reverse-phase detection voltage proportional to the fluctuation voltage. Is detected. Since the detection voltage having the opposite phase proportional to the fluctuation voltage is input to the error amplifier 28, the error amplifier 28 outputs an error signal so that the point C becomes zero. That is, the amplitude (frequency is always constant commercial frequency) of the error signal Y shown in FIG. 3 changes higher or lower according to the detection voltage of the opposite phase proportional to the fluctuation voltage input from the detection circuit 15, Comparator 29,
The pulse width of each PWM control signal generated from 30 is changed, and the PWM control signal is controlled so that the commercial AC voltage generated between the output terminals 8 and 9 becomes a predetermined rated voltage.

As described above, feedback is applied in accordance with the voltage fluctuation, and a constant commercial AC voltage is always generated between the output terminals 8 and 9. FIG. 4 is a waveform diagram showing one embodiment of each point according to the experiment of the present invention.

The experimental conditions are those when a resistive load is connected between the output terminals 8 and 9. In FIG.
The voltage waveform of the reference signal output from the detection circuit 15
The voltage waveform of the detection signal detected from the
A voltage waveform between 9 indicates a current waveform flowing through the inductors 5 and 6.

, Is 5 V / div on the vertical axis, 5 msec / div on the horizontal axis,
The vertical axis is 50 V / div, the horizontal axis is 5 msec / div, and the vertical axis is 20 A.
/ div, 5 msec / div on the horizontal axis. As shown in FIG. 4, since the detection is performed by the resistors 21 to 24, no distortion occurs in the detection signal, and the error amplifier 28
, A clean sine wave error signal is obtained.

The anode voltage Vcc is obtained in the bridge circuit section 14 based on the DC power generated by the DC generator 12, but the DC power is obtained by the AC generator and the rectifier instead of the DC generator 12. Thus, the anode voltage Vcc of the bridge circuit section 14 may be used.

[0023]

As described above, according to the present invention, a resistor is connected between the output terminal and the ground for each output terminal.
Since the detection circuit is configured to divide the commercial AC voltage, there is no adverse effect of the distortion rate on the output waveform,
By selecting a large resistance value, a detection circuit with a small loss can be obtained.

Since a detection circuit is constituted by one OP amplifier and a resistor, the cost is reduced and
By changing the input terminal of the amplifier, a detection signal having the same phase as that of the output waveform and a phase opposite to that of the output waveform can be obtained, and the circuit after the error detection unit can be freely handled.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 shows an embodiment of a specific circuit of the present invention.

FIG. 3 is an explanatory diagram of a waveform of generation of a PWM control signal.

FIG. 4 is a waveform diagram of one embodiment of each point according to the experiment of the present invention.

FIG. 5 is a diagram of a conventional output detection circuit.

[Explanation of symbols]

 1, 2, 3, 4 Transistor 5, 6 Inductor 7 Capacitor 8, 9 Output terminal 10 Detection transformer 11 Engine 12 DC generator 13 Stabilization circuit 14 Bridge circuit unit 15 Detection circuit 16 Error detection unit 17 PWM signal generation circuit 18, 19 Inverter 21, 22, 23, 24 Resistance 25 Differential Amplifier 26 Sine Wave Generation Circuit 27 Triangular Wave Generation Circuit 28 Error Amplifier 29, 30 Comparator

Claims (1)

(57) [Scope of request for utility model registration] A transistor (1, 1) controlled by a PWM control signal from a PWM signal generation circuit (17) using a voltage generated from an engine driven generator as a drive source.
In a power supply device that includes a bridge circuit section (14) including (2, 3, 4) and generates a commercial AC voltage at output terminals (8, 9), an output terminal (8, 9) is provided for each output terminal (8, 9). , 9) and the ground, the resistors (21, 22) connected in series, respectively.
And (23, 24) are connected, and a resistor (2
Occurrence at each series connection point of (1, 22) and (23, 24)
A detection circuit (15) configured to receive each divided voltage of the AC voltage by the differential amplifier (25); and obtaining an error signal from the detection signal and the reference signal detected by the detection circuit (15) to obtain the PWM signal. Generation circuit (17)
And an error detection unit (16) for feeding back to the power supply.