JP3250185B2 - Output stabilization method for load power supply with unstable output characteristics and pulse width control device for output current of current source inverter used for it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stabilizing the output of a load power supply having unstable output characteristics and a pulse width control device for the output current of a current source inverter used in the method.

[0002]

2. Description of the Related Art Conventionally, a switching power supply of a current-source inverter type has been used to supply a current according to a desired operation to various loads. Among the loads, feedback control is performed in a load power supply in order to stabilize the output of a laser device or the like whose output characteristics are unstable. In this feedback control, the difference between the current set value and the detected current value is multiplied by a proportional gain by a proportional operation (P control) and input to a pulse width control circuit as a current control signal, thereby changing the pulse width of the inverter output current. Adjustments have been made.

[0003] However, in the case of the current-source inverter system that outputs a current in a pulse form, when the proportional gain is small, the control deviation increases, so that the rise of the output current deteriorates. If you increase the proportional gain to improve this,
The control system may become unstable in a high frequency range. When a load such as a laser device requiring a fast response (up to 2 kHz) is operated by using a power supply controlled by a control system having a possibility that this kind of instability may occur, the output current may oscillate. There are problems that the laser output becomes unstable, the ripple of the current waveform increases, and the heat generated by the transistors used in the inverter and the like increases.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and the control system is stable even for a load having an unstable output characteristic such as a laser device. It is therefore an object of the present invention to provide a method for stabilizing the output of a power supply in which the output does not become unstable and a pulse width control device for the output current of a current source inverter used for the method.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the problems of the prior art, and as a result, introduced an integrator into the control system and integrated operation (I control) only when the pulse signal was on. When the pulse signal is off, the control deviation with respect to the previous pulse current is held. In addition, the integrator is disconnected and the current control signal (current command value) is forcibly output as 0, so that a quick response ( The inventors have found that the output of a load power supply such as a laser device requiring a maximum of 2 kHz) can be stabilized, and have completed the present invention.

According to the power supply output stabilization method of the present invention , an integrator is provided in front of a pulse width control circuit, and the output of a load power supply whose output characteristics are unstable by a current-source inverter method using feedback control. An output stabilization method for stabilizing a current, wherein a step of calculating a difference between a current setting value and a load current detection value, and a second switch provided on an output side of the integrator.
And the end of the rise of the load current detection value.
After that, the first switch provided on the input side of the integrator
Switch to open the input from the integrator to the pulse width control circuit.
Starting procedure and a predetermined procedure after the second switch is turned on.
After a lapse of time, the first switch and the second switch are turned off.
Off, and the input from the integrator to the pulse width control circuit is
And a step of stopping .

A first aspect of the pulse width control device for an output current of a current source inverter according to the present invention is a comparator that compares a current set value and a load current detection value and outputs a difference between the set value and the load current detection value. An integrator that generates a pulse width control signal of the current source inverter by an input, a pulse width control circuit to which a pulse width control signal from the integrator is input, and a pulse width control circuit interposed between the comparator and the integrator A first switch element, a second switch element interposed between the integrator and the pulse width control circuit, and a time delay element for controlling on / off of the first switch element by an external signal. a first switch control circuit having, a second switch control circuit for controlling the on-off of the second switch element of the same signal as the first switch control circuit, said second switch
When the element is turned on by the second switch control circuit,
In addition, the first switch element sets the load current detection value.
After the ascending is completed, the first switch control circuit turns off the switch.
And after a lapse of a predetermined time, the first switch element
Is turned off by the first switch control circuit, and
The second switch element is turned off by the second switch control circuit.
Input from the integrator to the pulse width control circuit.
It is characterized in that the force is stopped .

A second aspect of the pulse width control device for the output current of the current source inverter according to the present invention is a comparator that compares a current set value with a load current detection value and outputs a difference between the current set value and the load current detection value.
An integrator that generates a pulse width control signal of the current source inverter based on an input from the comparator, a chopper pulse width control circuit that receives a pulse width control signal from the integrator, the comparator and the integrator, comprising a switching element interposed between a chopper driven by the chopper pulse width control circuit, and a switch control circuit having a time delay element for controlling the on-off of the switching element by a signal from the outside , The first switch element is the load
After the rising of the current detection value is completed, the first switch control is performed.
Turned on for a predetermined period by the control circuit and the difference is input to the integrator
And the pulse current detection from the current setting value and the chopper
The difference obtained by comparing the value with the value is output to the output from the integrator.
The signal is further corrected and input to the chopper pulse width control circuit . In that case, chopper pulse width system
A proportionalizer is provided before the control circuit, and the current set value and chopper
The difference obtained by comparing with the pulse current detection value from
Corrected by the output from the integrator and input to the proportional unit
Preferably.

[0009]

In the method for stabilizing the output of a power supply according to the present invention, an integration process is performed in control by a current source inverter system using feedback control. Moreover, since the control deviation obtained by removing the rising portion of the detected current is integrated to obtain the current control signal (current command value),
The obtained current control signal is stable as well as having no control deviation. Further, the gain can be reduced by appropriately adjusting the integration processing time, so that the control system does not become unstable. Therefore, the output of a load power supply having unstable output characteristics can be stabilized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the attached drawings, but the present invention is not limited to only such embodiments.

FIG. 1 is a block diagram of an embodiment of a control system used in the method of stabilizing the output of a power supply according to the present invention, FIG. 2 is a circuit diagram of a main part of the block diagram, FIG. FIG. 4 is a block diagram of another embodiment of a circuit used in the power supply output stabilization method of the present invention, and FIG. 5 is a control block diagram of the main part. In the figure, 1 is a comparator, 2 is an integrator, 3
Is a pulse width control circuit (PWM modulation circuit), 4 is a current source inverter, 5 is a time delay element, 6 is a DC power supply, 7 is a chopper, 8 is a rectifier, 9 is a laser device, 10 is a proportional device, 1
1 denotes a chopper pulse width control circuit, and Z denotes an impedance.

In the embodiment shown in FIGS. 1 to 3, first, consider the case where an on / off pulse current is supplied to the discharge tube. In this pulse current control, a pulse signal for controlling ON / OFF of a pulse and a current setting value Is for giving a current command value are used. First, the comparator 1 compares the current setting value Is with the current detection value Ir to determine the deviation (control deviation) ΔI. The obtained deviation ΔI is
The signal is input to the integrator 2 via a switch S1 which is opened and closed intermittently by a pulse signal for controlling ON / OFF of the pulse. The integrator 2 performs an integration process on the input deviation ΔI only while the switch S1 is on, that is, when the pulse signal is on, and outputs a current control signal Ic. The output current control signal (current command value) Ic is
1 is input to a pulse width control circuit (PWM modulation circuit) 3 via a switch S2 which is opened and closed by the same pulse signal. When the pulse signal is off, the integrator 2 is held and the current control signal Ic is set to 0. The pulse width control circuit 3 inputs a pulse current Ip having a pulse width corresponding to the input current control signal Ic to an output current control unit of the current source inverter 4. Thus, the current source inverter 4 can output a current I having a pulse width corresponding to the input pulse current Ip to the load.

The integrator 2 used here includes:
For example, as shown in FIG. 2, an operational amplifier is used, and has a function capable of holding the values when the switches S1 and S2 of the input terminal and the output terminal are opened. The time delay element 5 is formed by impedances Z1 and Z2, and the value is appropriately set according to a desired time constant. The other impedance values represented by the symbol Z are appropriately set according to the needs of the inserted portion, and the values are not necessarily the same.

Next, the configuration and operation of the switches S1 and S2 provided before and after the integrator 2 will be described in detail.

The switches S1 and S2 are both constituted by analog switches. The switch S1 and the switch S2 are turned on / off by the pulse signal that controls the on / off of the pulse as described above. Then, as shown in FIGS.
Is turned on and off by a pulse signal passing through the time delay element 5, so that it is delayed from the switch S2 whose on / off is controlled by the pulse signal not passing through the time delay element. Turned on . The time constant of the time delay element 5 is set in consideration of a rising time from a rising state immediately after the detection of the current detection value Ir to a stable state (see FIG. 3). That is, after the current detection value Ir reaches a stable state, the switch S1
Ounce is set to so that. Since the opening and closing of the switch S1 is controlled in this manner, the input signal to the integrator 2 is stabilized, and the current control signal Ic does not become unstable.
Therefore, the output current I of the inverter 4 is also stabilized, so that the load can be operated stably. Also, as described above, even when the switches S1 and S2 are off , the integrator 2 holds the value, and the switch S2 is also turned on in synchronization with the current detection timing.
Since it is off, the value held by the integrator 2 is output simultaneously with the current detection (see FIG. 3). Further, when the pulse signal is off, the integrator 2 is disconnected, and the current control signal Ic is set to 0. Therefore, the rise of the output current from the current source inverter 4 is sharpened, and the control system does not become unstable even with a load that requires a quick response. Note that when the pulse signal is off, the current control signal Ic is set to 0. For example, the current control signal Ic is turned on when the pulse signal is off at the outlet side of the integrator 2 (and downstream of the switch S2), and the pulse signal is turned off. It is also achieved by grounding through a switch that turns off when on.

FIGS. 4 and 5 show another embodiment of the present invention. In the embodiment shown in FIGS. 4 and 5, a chopper 7 is used instead of the switch S2. Therefore, the output (current control signal Ic) of the integrator 2 is input to the chopper pulse width control circuit 11. More specific
Specifically, as shown in FIG. 5, the current set value Is and the chopper
The difference from the detected value of the pulse current Ip of FIG.
The current control signal Ic corrected by the force is the chopper pulse width
It is input to the control circuit 11. Further, the chopper pulse width control circuit 11, Cho as the current control signal Ic
Tsu path 7 is controlled, whereby the chopper 7 pulse current Ip
Is input to the output current control unit of the current source inverter 4. As a result, the current source inverter 4 has
A current I having a pulse width corresponding to the input pulse current Ip can be output to the load.

In this embodiment, the proportional unit 10 is provided before the chopper pulse width control circuit 11.

[0018]

As described above, according to the present invention, the power supply output can be stabilized because no control deviation occurs and the control system does not become unstable even in a high frequency range. Therefore, the load can be operated stably.
Therefore, it is possible to stabilize the output of a load such as a laser device that requires a quick response.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a control system used for a method of stabilizing the output of a power supply according to the present invention.

FIG. 2 is a main part circuit diagram of the block diagram.

FIG. 3 is a time chart of the block diagram.

FIG. 4 is a block diagram of another embodiment of a circuit used for the power supply output stabilization method of the present invention.

FIG. 5 is a control block diagram of the main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Comparator 2 Integrator 3 Pulse width control circuit (PWM modulation circuit) 4 Current source inverter 5 Time delay element 6 DC power supply 7 Chopper 8 Rectifier 9 Laser device 10 Proportional unit 11 Chopper pulse width control circuit Z impedance

Continuation of the front page (56) References JP-A-4-88885 (JP, A) JP-A-4-46588 (JP, A) JP-A-3-226277 (JP, A) JP-A-59-10174 (JP) , A) JP-A-57-142178 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/48

Claims (4)

(57) [Claims] An integrator is provided before a pulse width control circuit.
Te, to stabilize the output of the power supply output characteristic is unstable load by current source inverter system using feedback control
An output stabilization method comprising: calculating a difference between a current setting value and a load current detection value; and turning on a second switch provided on an output side of the integrator.
That the procedure, after the rise of the load current detection value is completed, the integrator
Turns on the first switch provided on the input side of the
Starting the input to the pulse width control circuit from
2 After a predetermined time has passed since the switch was turned on,
Turning off the first switch and the second switch,
Stopping the input to the pulse width control circuit from the power supply. 2. A comparator for comparing a set current value and a detected load current value and outputting a difference therebetween; an integrator for generating a pulse width control signal of a current source inverter based on an input from the comparator; A pulse width control circuit to which a pulse width control signal from an integrator is input; a first switch element interposed between the comparator and the integrator; and a pulse width control circuit including the integrator and the pulse width control circuit. The second switch element interposed therebetween and the first switch element are turned on by an external signal.
- comprising a first switch control circuit having a time delay element for controlling the off and a second switch control circuit for controlling the on-off of the second switch element of the same signal as the first switch control circuit, said first The two switch element is controlled by the second switch control circuit.
And the first switch element is turned on
The first switch after the completion of the rise of the load current detection value;
Turned on by the control circuit, and then after a predetermined time
The first switch element is turned off by the first switch control circuit.
And the second switch element is the second switch
The pulse is turned off by the control circuit and is output from the integrator.
A pulse width control device for an output current of a current source inverter , wherein an input to a width control circuit is stopped . 3. A comparator for comparing a set current value and a detected load current value and outputting a difference therebetween; an integrator for generating a pulse width control signal of a current source inverter based on an input from the comparator; A chopper pulse width control circuit to which a pulse width control signal from the integrator is input; a switch element interposed between the comparator and the integrator; and a chopper driven by the chopper pulse width control circuit. A switch control circuit having a time delay element for controlling on / off of the switch element by an external signal , wherein the first switch element detects a rise of the load current detection value.
After the termination, the first switch control circuit performs a predetermined period of time.
Is turned on, the difference is input to the integrator, and the current setting value and the pulse current detection value from the chopper are calculated.
The difference obtained by the comparison is complemented by the output from the integrator.
A pulse width control device for an output current of a current source inverter, wherein the pulse width is controlled and input to the chopper pulse width control circuit . (4) The output of the current source inverter according to claim 3.
In the current pulse width control device, A proportionality device is provided before the chopper pulse width control circuit, Compare the current setting with the pulse current detection value from the chopper
The obtained difference is corrected by the output from the integrator.
Input to the proportional device by means of
Pulse width control device for the output current of the motor.