JPH0624437B2 - DC power supply voltage control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control circuit of a DC power supply device having a capacitive load such as an electron beam device which is likely to cause a short circuit, and more particularly to a short circuit protection and a rapid voltage recovery circuit. Regarding configuration.

[Conventional technology]

In a DC high-voltage power supply device that requires miniaturization of a power supply device, there is a so-called modulation type DC power supply device in which a DC is once converted into a high frequency AC by using a chopper and an inverter, and the AC is converted into a DC again by a rectifier circuit. Used.

FIG. 4 is a block diagram showing an example of the modulation type DC high voltage power supply device. The output current of the DC power supply 1 is controlled by the switching element 2A of the semiconductor type step-down chopper 2 and converted into an AC current by the inverter 4. After that, the AC current increased to a predetermined high voltage by the step-up transformer 5 is rectified by the rectification bridge 6 and becomes a DC high voltage with ripples removed by the smoothing capacitor 7 and is supplied to the load 8.

Output voltage V of the DC high-voltage power supply unit 10 configured in this way
Is controlled by the chopper control circuit 11. That is, the chopper control circuit 11 receives the detection signal 9E of the detector 9 of the output voltage V and the voltage setting signal 12E of the setter 12 of the output voltage V as input signals, and an automatic voltage regulator (abbreviated as AVR hereinafter) 13 And an automatic current regulator (hereinafter abbreviated as ACR) using as input signals the chopper current setting signal 13E which is the output of the AVR 13 and the chopper current detection signal 16E which is the output of the current detector 16 which detects the output current of the semiconductor chopper 2. 14) and a pulse former 15 for shaping the output signal of the ACR and outputting a control signal 11E for controlling the on / off time ratio of the switching element 2A.
Composed of and.

Therefore, the switching element 2A sets the ACR as a minor loop so that the detection side input signal 9E of the AVR 13 becomes equal to the setting signal 12E and the chopper current detection side input signal 16E of the ACR 14 becomes equal to the output voltage control signal 13E of the AVR 13. Is controlled by the output control signal 11E of the AVR control type chopper control circuit 11,
Since the output current of the semiconductor chopper 2 and the current supplied to the load 8 are balanced, the output voltage V of the DC power supply unit 10 is held at a constant voltage value.

[Problems to be Solved by the Invention]

By the way, when the load of the DC high-voltage power supply device is an electron beam processing machine, an electron beam irradiation device, or the like, several tens of KV
Since the electron gun to which a DC voltage of order or higher is applied and the object to be processed by the electron beam are housed in the same vacuum chamber, the occluded gas is released from the object to be processed and the electrode at the time of starting, There is a problem that load short-circuiting occurs repeatedly due to the influence, and the occurrence frequency gradually decreases with the progress of aging, and reaches a steady operation state in which machining can be performed. Therefore, the output side of the DC high-voltage power supply device is repeatedly short-circuited, and the stored energy of the smoothing capacitor 7 provided for reducing the voltage overshoot or ripple generated when the voltage is restored is discharged each time the load is short-circuited. Therefore, a large amount of charging energy is needed to charge the smoothing capacitor when the voltage is restored. However, the transient response speed of the AVR is usually determined by the load time constant which is almost determined by the load resistance of the load rating 8 and the electrostatic capacity of the smoothing capacitor 7.
When a load short circuit occurs repeatedly in the DC high-voltage power supply device configured in this manner, the time required for voltage recovery increases, and during that time, the electron beam stops and processing unevenness and quality variations occur on the workpiece. The inconvenience occurs.

An object of the present invention is to provide a chopper control circuit with a load short-circuit protection function and a voltage early recovery function.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, a direct current power supply unit having a semiconductor chopper receives an output signal from an output voltage setter and a detector to settle the output voltage, and the automatic voltage regulator. A regulator and an automatic current regulator for adjusting the output current of an output current detector of the semiconductor chopper to set the chopper output current, and a pulse forming for turning on / off the semiconductor chopper by receiving the output signal of the automatic current regulator In a device having a chopper control circuit, the protection circuit detects a load short circuit of the DC power supply unit and temporarily stops the signal output of the pulse former, and the automatic current triggered by a signal from the protection circuit. The magnitude of either one of the input signals of the regulator is controlled so that a sudden increase in the chopper output current is prompted at the same time as the suspension is completed. A charge control circuit, the output voltage is assumed and a settling recovery circuit for commanding the operation stop of the quick charge control circuit detects that it has recovered to a predetermined level.

[Action]

In the above means, the protection circuit detects the short-circuit current flowing in the load circuit and sends the pulse-off signal to the pulse shaper, so that the switching operation of the semiconductor chopper is temporarily stopped and the output voltage of the DC power supply unit becomes the load. The short-time required for recovery from a short circuit is reduced and the withstand voltage performance of the load is recovered. In addition, the quick charge control circuit triggered by the signal from the protection circuit controls the magnitude of either one of the two input signals of the ACR to prevent the sudden increase of the chopper output current, thereby releasing the pulse off. The output voltage of the rear DC power supply unit sharply rises, and a high-rise voltage is applied to the load whose withstanding voltage performance has been restored. further,
By providing a settling recovery circuit that stops the operation of the quick charge control circuit by detecting that the output voltage has reached a predetermined level close to the settling voltage of AVR, the output voltage is then set by the output voltage settling function of AVR. The voltage specified by the output voltage setting unit is reached and the DC voltage with a small ripple is output from the DC power supply unit.

〔Example〕

 The present invention will be described below based on examples.

FIG. 1 is a circuit configuration diagram showing an apparatus according to an embodiment of the present invention, and the same parts as those of the conventional apparatus are designated by the same reference numerals and detailed description thereof will be omitted. In the figure, 20 is a voltage control circuit including a chopper control circuit (consisting of reference numerals 12, 13, 14, and 15), and a protection circuit 21 is triggered by a short-circuit current detector 17 and an output signal of the detector 17. Short circuit signal generator 2 that outputs a short circuit signal 22E
2, H level signal 2 set by the short circuit signal 22E
It is composed of a flip-flop 23 holding 3E and a pulse-off signal generator that outputs a pulse-off signal 24E that is L-level for a predetermined time by being triggered by an H-level signal 23E. The pulse-off signal 24E causes the chopper control signal of the pulse former 15 to be generated. 11E is AVR, ACR
It stops for a predetermined time regardless of the settling state.

26 is an amplification factor switching device as a quick charge control circuit,
When the output signal 23E of the flip-flop 23 changes from the L level to the H level, the amplification factor is changed from g ₁ to g.
₂ (where g ₁ > g ₂ ), and the detection signal 16E of the chopper current detector 16 is converted into a signal 26E whose magnitude is reduced by a factor of g ₂ / g ₁ and is converted into an ACR. This is equivalent to switching the ACR chopper current setting to g ₁ / g ₂ times. After that, when the temporary stop of the chopper control signal 11E by the protection circuit 21 is released, the chopper current rapidly increases, the smoothing capacitor 7 is rapidly charged based on this, and the output voltage V rapidly increases.

Reference numeral 27 denotes an AVR and ACR settling recovery circuit, which outputs the output setting signal 12E of the output voltage setting unit 12 to an amplification factor g ₃ (g
Amplifier 28 and amplifier 2 that amplifies at ₃ ≈ 0.9)
8 and the output detection signal 9E of the voltage detector 9 are used as input signals for the comparator 29. When the detection signal 9E reaches the same level as the output signal of the amplifier 28, the reset signal 29E is flip-flopped. Output to the flip-flop 23, the flip-flop 23 outputs the output signal 23E.
Becomes an L level, the amplification factor of the quick charge control circuit 26 returns from g ₂ to g ₁ , and the AVR and ACR return to the steady settling control state.

FIG. 2 is a time chart showing the operation of the apparatus of the embodiment, in which the output voltage V of the DC power supply unit is operated at the settling voltage V ₁ by the output voltage setting unit 12 and the load 8 is short-circuited to the load 8 at time t _0. It is assumed that At this time, the load current I is instantaneously changed from the settling current I ₁ to the short-circuit current I 1.
This current Is is detected by the short-circuit current detector 17, and the short-circuit signal generator 22 outputs a pulsed short-circuit signal 22E, so that the flip-flop 23 receiving this outputs the H-level signal 23E. Output. Signal 23
The pulse-off signal generator that receives E needs t for the short-circuit recovery.
Pulse off signal 24E which changes ₁ -t ₀ hour L level
And the output of the chopper control signal 11E from the pulse former 15 is temporarily stopped, so that the chopper output current Ic, the load current I ₁ and the output voltage V ₁ are reduced, and the load short circuit is recovered. Also, the H-level signal 23E
The amplification factor switch 26 as a quick charge control circuit triggered by the operation causes the amplification factor to decrease from g ₁ to g ₂ , so that the level of the ACR detection side input signal 28E decreases and the control signal from the AVR 13 decreases. Since the voltage difference with 23E increases, the ACR enters a standby state for quick charging, and the pulse shaper 15 outputs the chopper control signal 11E having a wide pulse width at the end time t ₁ of the temporary stop, which results in a large chopper output current. Then, the smoothing capacitor 7 is rapidly charged, and the output voltage V again sharply increases toward V ₁ . When the output voltage V recovers to a voltage (V ₁ × g ₃ ) determined by the amplification factor g ₃ of the amplifier 28 of the settling recovery circuit 27 at time t ₂ , the comparator 29 operates and the reset signal 29E causes the output H level of the flip-flop. The signal 23E goes to the L level, and the amplification factor switch 26 as the quick charge control circuit returns from the amplification factor g ₂ to the amplification factor g ₁ in the steady operation accordingly, so that the rapid charging is stopped, and thereafter AVR, The steady settling operation of the ACR causes the output voltage to gradually rise toward V _1, and the settling voltage V ₁ can be recovered without causing overshoot due to the sudden rise in the output voltage.

FIG. 3 is a circuit configuration diagram showing a device according to another embodiment of the present invention. The voltage control circuit 30 has an amplification factor switch 35 as a quick charge control circuit on the output side of the AVR, and the flip-flop 23 has an H level. Output signal 23E of t ₂
It differs from the previous embodiment in that it is configured to increase the amplification factor from g ₂ to g ₁ in reverse during −t ₀ period.
Is increased to g ₁ / g ₂ times (g ₁ > g ₂ ), and the difference between the signal 36E and the detection signal 16E of the chopper current spreads, so that the ACR causes the increase in the chopper current via the signal pulse former 15. Since the output is directed toward the gate of the semiconductor switching element 2A of the chopper 2, the output voltage V can be rapidly increased from the time t _{1 to the} time t ₂ .

The voltage control circuit of the present invention requires not only voltage recovery after load short-circuiting of a DC high-voltage power supply using an electron beam device or the like, but also a DC voltage with a quick rise of voltage at startup and less overshoot. It can be widely applied to a DC power supply device having a load.

〔The invention's effect〕

As described above, the present invention issues a command for detecting a load short circuit and stopping the chopper output current for a predetermined period of time to the DC high voltage power supply device which performs the output voltage of the DC power supply unit having the chopper by controlling the chopper output current. A protection circuit,
A quick charge control circuit that prompts a rapid increase in the chopper output current after the chopper current suspension time, and the quick charge is stopped when the output voltage is restored to a predetermined level by the quick charge.
A settling return circuit for returning to the settling control of the output voltage by VR and ACR is provided. As a result, the protection circuit operates at the same time as the load short circuit, the output voltage and the load current are once reduced, and the withstand voltage performance of the load is restored, and the quick charge control circuit operates immediately.
The smoothing capacitor can be charged with a current larger than that in the normal state to rapidly raise the output voltage. Further, when the output voltage suddenly rises to near the output voltage before the load is short-circuited, the settling recovery circuit operates to stop the operation of the quick charge control circuit and shift to the settling operation, whereby the voltage overshoot can be suppressed to a small level. Therefore, the delay of the voltage recovery time due to the slow transient response speed of the AVR, which is a problem in the conventional device, can be avoided.

In particular, when the load is a high voltage load such as an electron beam device in which a load short circuit is likely to occur, the voltage recovery time after the load short circuit is short circuited, and the stop time of the electron beam or the like is short circuited. It is possible to obtain an advantage that it is possible to prevent processing unevenness and quality variations of the processed body. Further, by shortening the voltage recovery time, it is possible to avoid the voltage from overshooting, so that the vicious cycle of increasing the frequency of load short-circuiting due to overshooting is prevented.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and FIG.
FIG. 4 is a time chart showing the operation of the device of the embodiment, FIG. 3 is a circuit configuration diagram showing a different embodiment, and FIG. 4 is a circuit configuration diagram showing the conventional device. 2 ... Semiconductor chopper, 7 ... Smoothing capacitor, 8 ...
... load, 9 ... voltage detector, 10 ... DC power supply section, 11
...... Chopper control circuit, 12 …… Output voltage setting device, 13
...... Automatic voltage regulator (AVR), 14 ...... Automatic current regulator (ACR), 15 ...... Pulse former, 16 ...... Chopper current detector, 17 ...... Short circuit current detector, 20, 30 ...
... voltage control circuit, 21 ... protection circuit, 26, 36 ... quick charge control circuit (amplification factor switch), 27 ... settling recovery circuit.

Claims (1)

[Claims] 1. An automatic voltage regulator in which a DC power supply unit having a semiconductor chopper receives an output signal of an output voltage setter and a detector to settle the output voltage, and an output current of the automatic voltage regulator and the semiconductor chopper. A chopper control circuit including an automatic current regulator that receives the output signal of the detector and stabilizes the output current of the chopper, and a pulse generator that receives the output signal of the automatic current regulator and performs on / off control of the semiconductor chopper One of a protection circuit that detects a load short circuit of the DC power supply unit and temporarily stops the signal output of the pulse former, and an input signal of the automatic current regulator that is triggered by a signal from the protection circuit. A quick charge control circuit that controls one of the magnitudes and prompts a rapid increase in the chopper output current at the same time as the end of the suspension, and an output voltage Voltage control circuit for a DC power supply apparatus characterized by comprising a settling recovery circuit detects that it has recovered to the level commands operation stop of the quick charge control circuit.