JPH0624438B2 - Control method of DC high-voltage power supply device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC high-voltage power supply device, and more particularly, to a voltage recovery method in a device having a load such as an electron beam processing machine that easily causes a load short circuit.

[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 a 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 step-down chopper 2 and converted into an AC current by the inverter 4. After that, the voltage is supplied to the primary winding of the step-up transformer 5. The alternating current increased to a predetermined high voltage by the step-up transformer 5 is rectified by the rectifying 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. The output voltage V of the DC power supply unit 10 is controlled by the output control signal 11E of the AVR control circuit 11 and the output current of the semiconductor chopper 2 and the current supplied to the load 8 are balanced. Held in.

[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 required to charge the smoothing capacitor at the time of voltage recovery, which causes the DC high-voltage power supply device to have a much shorter time capacity than the power supply capacity required to generate an electron beam. The problem occurs. If the voltage recovery is slow, the electron beam stop period becomes long and the quality of the workpiece is uneven, so fast voltage recovery is required, which also necessitates a further increase in the short-time capacity of the power supply. It

An object of the present invention is to suppress an increase in short-time capacity of a power supply device and to shorten an electron beam stop time during steady operation by controlling a voltage recovery speed in accordance with a frequency of load short circuit. It is in.

[Means for Solving the Problems] In order to solve the above problems, according to the method of the present invention, a repetitive load short circuit of a DC high-voltage power supply device having a chopper held at an output voltage based on a settling condition of a chopper control circuit is provided. Is a method for recovering output voltage against the output voltage of the chopper, the output current of the chopper is throttled for a predetermined time, and then the output voltage is rapidly recovered to a predetermined voltage level by the chopper output current exceeding the set value of the chopper control circuit. A rapid recovery mode and a normal recovery mode in which the rapid acceleration mode is switched to the set value of the chopper control circuit when the recovery command time of the rapid recovery mode is integrated and the integrated value reaches the upper limit threshold level. Depending on the frequency of load short-circuiting, it will be repeated multiple times alternately.

[Action]

In the above means, AVR and A of the chopper control circuit
If a load short circuit occurs repeatedly in the DC high-voltage power supply device in which the chopper output current and DC output voltage are settled to the set values by CR, output voltage recovery control is performed multiple times in the rapid recovery mode and command time in the rapid recovery mode. Is configured and when the integrated value reaches a predetermined upper threshold level, it is switched to the set value of the chopper control circuit and a plurality of normal recovery modes are alternately performed according to the frequency of load short circuit. As a result, the normal recovery mode functions during the aging period of the load where the frequency of load short-circuit occurrence is high, which makes it possible to suppress the short-term capacity increase of the power supply device and to reduce the frequency of load short-circuit occurrence during steady operation. In the state, the control by the quick recovery mode is the main, and the stop time of the electron beam is short-circuited, so it occurs with the stop of the electron beam. Variations and deterioration of the quality of the workpiece can be prevented.

〔Example〕

 The present invention will be described below based on examples.

FIG. 1 is a block diagram of an apparatus for explaining an embodiment method of the present invention, FIG. 2 is a time chart of each part in the embodiment method, and FIG. 3 is an operation explanatory view showing the embodiment method. The same parts as those in FIG. In FIG. 1, 20 is a quick recovery control circuit, 30 is a normal recovery control circuit,
The circuit configuration and its operation will be described with reference to the drawings and FIG. It is assumed that a load short circuit occurs at time t ₀ during operation with the settling output voltage V ₁ and load current I ₁ of the chopper control circuit 11 and a short circuit current Is flows. The short circuit current Is is detected by the short circuit current detector 17, and the short circuit signal generator 22 outputs a short circuit signal 22E.
3 is set, and the H-level signal 23E is output.
In response to this, the pulse-off signal generator 24 outputs the pulse-off signal 2 which is at the L level for a predetermined time from time t ₀ to time t _1.
4E is output to the pulse former 15, the output signal of the pulse former 15 is stopped, and the output current Ic of the chopper 2 is stopped.
Stops during time t ₀ to t ₁ . As a result, both the output voltage V and the load current I drop to near zero, and the load 8
Withstand voltage performance is restored. On the other hand, when the integrated value of the integrating circuit 32 is less than or equal to the upper limit threshold S ₁ , the integrating circuit is H level.
Since the level signal is output to the AND gate 33,
During signal 34E of _{t 2} from time _{t 1} is a rapid recovery instruction time from D gate 33 is output, _{g 2} a gain switcher 26 from the amplification factor _{g 1} as shown in the waveform 26E having received the
Switch to (g ₁ > g ₂ ). As a result, the detection signal 16E of the chopper current detector 16 has a magnitude of g ₂ / g ₁
It is converted into a signal 26E that has been doubled. This is A
Since this is equivalent to increasing the setting of the CR chopper current, the ACR 14 issues a command to increase the chopper current Ic to Ir via the pulse former 15 to the chopper control signal 11
Since it is output to the semiconductor switching element 2A as E, the output voltage V of the DC high-voltage power supply unit 10 exhibits a faster rise than in the normal recovery mode determined by the settling condition of the chopper control circuit 11, and is close to the settling voltage V ₁ at time t _2. Recover to. The voltage V is input to the comparator 29, and the output voltage setting signal 12E is compared with the setting signal of the reduction level that has passed through the amplifier 28 for reducing the output voltage setting signal 12E by the amplification factor g ₃ (g ₃ is 1 or less), thereby the output voltage V Is a level g close to the settling voltage V _1.
At time t ₂ when ₃ × V ₁ is reached, the flip-flop 23 is reset, and the output H level signal 23E changes to the L level signal, so that the amplification factor switcher 26 changes its amplification factor from g ₂ to g ₁ . Since the chopper output current also returns from Ir to Ic based on this, the output voltage V returns to the normal recovery mode based on the settling condition of the chopper control circuit 11 and reaches the settling voltage V ₁ at a slow speed.
The occurrence of voltage overshoot due to rapid recovery is avoided.

On the other hand, the H level signal 23E passing through the AND gate 23,
The pulse-off signal 24E is input to the AND gate 34,
The integrated value of the integrator 32 is increased by the rapid recovery command time signal 34E from time t ₁ to time t ₂ when both signals overlap.

Again the load short circuit occurs at time t _3, when it recovers control of the voltage based on the rapid recovery mode described above is performed, the integrated value of the integrator 32 at time t ₅ has reached its upper threshold S _1, integrated The logic level of the device 32 changes to the L level, and the AND gate 33 outputs the H level signal 23E.
The gain switching unit 26E changes its gain from g ₂ to g ₁ , and the ACR 14
Returns to its settling level, resulting in a rapid recovery control circuit 2
At 0, the operation is stopped, and after time t ₅ , the operation recovers slowly toward the settling voltage V ₁ in the normal recovery mode based on the settling condition of the chopper control circuit 11.

The operation of shifting the output voltage V from the quick recovery mode to the normal recovery mode has been described above together with the configurations of the quick recovery control circuit 20 and the normal recovery control circuit 30. FIG. 3 is an explanatory diagram when a load short circuit occurs repeatedly. As shown, in the rapid recovery mode period, the integrating circuit output signal 32E is at H level, and every time a load short circuit occurs at this time ta, tb, tc, td, the integrator 32 increases (charges) its integrated value.
When the integrated value reaches the upper limit threshold value S ₁ , the integrated circuit output 32E becomes L level and the AND gates 33 and 34 prevent the passage of signals, and the normal recovery mode is reached. After the period, the integrated value does not increase even if a load short circuit occurs at times te, tf, and tg. When the integrated value gradually decreases at a predetermined discharge time constant and decreases to the lower limit threshold value S ₂ , the integrating circuit output 32E becomes H level again, and the rapid recovery mode period starts. Therefore, by adjusting the threshold values S ₁ and S _{2 of the} integrating circuit 32 and the set values of the charge / discharge time constants in advance, the load short circuit number in the rapid recovery mode period and the load short circuit number in the normal recovery mode period can be It is possible to control the ratio and suppress the short-term capacity increase of the DC high-voltage power supply device by the voltage recovery mainly in the normal recovery mode during the aging period of the electron beam device where the frequency of load short-circuiting is high. In the operating state of electron beam machining where the frequency of short circuits is low, the voltage recovery mainly in the rapid recovery mode shortens the electron beam stop time, resulting in uneven processing and deterioration of the quality of the workpiece caused by the electron beam stop. Can be prevented.

〔The invention's effect〕

As described above, in the present invention, the output voltage of the DC high-voltage power supply unit is settled by controlling the chopper output current in the chopper control circuit based on a predetermined settling condition. Output voltage recovery is performed in the rapid recovery mode and the normal recovery mode in which the signal proportional to the command time in the rapid recovery mode is integrated and when the integrated value reaches the upper threshold value, it is switched to the set value of the chopper control circuit. Is configured to be alternately repeated a plurality of times according to the frequency of load short circuit. As a result, in the operating state with few load short circuits, the voltage recovery mainly in the rapid recovery mode is performed, the adverse effect on the load is eliminated by short-circuiting the output voltage stop period, and the frequency of load short circuits is high. In this state, it becomes possible to mainly perform the voltage recovery in the normal recovery mode, so that it is possible to minimize the increase in the short-time capacity required for the power supply for charging the smoothing capacitor provided on the output side. . In particular, when the load is a load short circuit that repeatedly occurs at the time of startup, such as an electron beam processing machine or an electron beam irradiation device, the voltage is slowly recovered in the normal recovery mode during the aging period at startup. This prevents an increase in the capacity of the power supply for a short time and shortens the electron beam stop time by the rapid recovery mode during normal operation when the load short circuit frequency decreases. It is possible to avoid deterioration of quality based on the above.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus for explaining an embodiment method of the present invention, FIG. 2 is a time chart in the embodiment method,
FIG. 3 is an operation explanatory view of the embodiment method, and FIG. 4 is a configuration diagram showing a conventional device. 10 ... DC high-voltage power supply section, 11 ... Chopper control circuit,
20 ... Rapid recovery control circuit, 30 ... Normal recovery control circuit.

Claims (1)

[Claims] 1. A method of recovering output voltage against repeated load short-circuiting of a DC high-voltage power supply device having a chopper whose output voltage is held at the settling voltage based on the settling condition of a chopper control circuit, the method comprising detecting a load short-circuit. After the output current of the chopper is throttled for a predetermined time, a rapid recovery mode in which the output voltage is rapidly recovered to a predetermined voltage level by the chopper output current exceeding the set value of the chopper control circuit, and the recovery command time of the rapid recovery mode is integrated. When the integrated value reaches the upper limit threshold level, the rapid acceleration mode is switched to the settling value of the chopper control circuit and the normal recovery mode is alternately repeated a plurality of times according to the frequency of occurrence of load short circuit. A method of controlling a DC high-voltage power supply device, which is characterized in that: