JPH05137325A - Charge voltage control circuit - Google Patents

Abstract

PURPOSE:To improve the accuracy in control of charge voltage by preventing the influence of switching noise. CONSTITUTION:A subtraction and division circuit 31 calculates the number of times of switching required for charging a high voltage capacitor to a specified voltage from a voltage command value V8b and residual voltage detection value Vref. An A/D conversion circuit 32 converts the number of times of switching from an analog value to a digital value, and presets it in a counter circuit 33. The counter circuit 33 starts the count of the number of times of switching to the number of times of switching when a command signal S is input. A flip-flop circuit 34 outputs a signal corresponding to the operation command for starting or stopping the switching operation of an inverter switching circuit based on the number of times of switching. When the charge operation ends, the counter circuit 33 outputs a charge end signal EOC to the general control circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging voltage control circuit for a high voltage pulse charging power source applied to laser excitation of an excimer laser oscillator or the like.

[0002]

2. Description of the Related Art FIG. 3 shows a circuit block diagram of a conventional high voltage pulse charging power supply.

An alternating current is input to the rectifier circuit 2 from a three-phase or single-phase commercial power source 1 of 50 Hz or 60 Hz. The rectifier circuit 2 converts the alternating current into direct current and supplies it to the direct current smoothing capacitor 3.

The inverter switching circuit 4 provided at the subsequent stage of the DC smoothing capacitor 3 is constructed in a full bridge type using switching elements 4a to 4d such as high speed transistors or field effect transistors (FETs), and is composed of 4a, 4d and 4b. The switching elements according to the combination of 4c are simultaneously turned on or off for a predetermined time. Further, in the combination of the switching elements, the DC voltage of the DC voltage smoothing capacitor 3 is converted into a pulsed AC voltage by alternately turning on and off in a predetermined repeated synchronization. The generated pulsed AC voltage is boosted to a pulsed AC high voltage by the step-up transformer 5 having good high frequency characteristics. The high-voltage rectifier circuit 6 rectifies the pulsed AC high voltage, and charges the high-voltage capacitor 7 provided at the subsequent stage with a high-voltage pulse having a positive or negative predetermined polarity by its circuit configuration.

The voltage dividing resistor 8 is a resistance voltage dividing circuit for detecting the charging voltage value charged in the high voltage capacitor 7, which is composed of a series connection circuit of a high voltage side resistor 8a and a low voltage side resistor 8b. The charging voltage charged in the high voltage capacitor 7 is divided into a low voltage by the voltage dividing resistor 8 and output to both ends of the low voltage side resistor 8b. Normally, one of the low voltage side resistors 8b is connected to the ground potential. The output voltage value V8b output across the low voltage side resistor 8b is input to the comparator 9.

A normal voltage comparator is used for the comparator 9, and the divided voltage detection value of the charging voltage value of the high voltage capacitor 7, that is, the output voltage V8b of the low voltage side resistor 8b and the high voltage input from the overall control circuit 10 are used. The drive circuit 11 is controlled by comparing with the voltage command value Vref for the voltage capacitor 7. The drive circuit 11 turns on or off the switching elements 4a to 4d of the inverter switching circuit 4 at a switching frequency of several tens KHz according to the signal from the comparator 9.

The overall control circuit 10 outputs a voltage command value Vref to the comparator 9 in response to an operation or command from the outside, and also outputs a command to the drive circuit 11 to start the operation of the inverter switching circuit 4. Further, the overall control circuit 10 outputs the signal EOC indicating that the charging voltage value of the high-voltage capacitor 7 becomes larger than a predetermined value because the voltage detection value V8b becomes larger than the voltage command value Vref, and the comparator 9 outputs the signal EOC. Input, display or output a predetermined signal to the outside. Here, the conventional charging voltage control in the above-mentioned high voltage pulse charging power supply will be described.

The overall control circuit 10 outputs a voltage command value Vref to the comparator 9 by an operation or a command from the outside, and also outputs a command to the drive circuit 11 to start the operation of the inverter switching circuit 4. The drive circuit 11 operates the inverter switching circuit 4 to charge the high voltage capacitor 7 with a voltage rise value per switching determined by a predetermined charging energy per switching. The detected value V8b of the charging voltage during charging of the high-voltage capacitor 7 is shown in FIG. Here, t = t0 is the charging start time, and t = ts is the time when the charging voltage reaches the voltage command value Vref. Also,
V8b (t0) is the detected value of the residual voltage of the high voltage capacitor 7 at t = t0.

Further, the comparator 9 has an inverter switching circuit as shown in FIG. 4 (b), as shown in FIG. 4B, from t = t0 until t = ts when the detected value V8b of the charging voltage becomes larger than the voltage command value Vref. The signal for operating 4 is output. After t = ts, a signal for stopping the operation of the inverter switching circuit 4 is output, and since the predetermined charging is completed, the charging end signal EOC is output to the overall control circuit 10.

[0010]

However, in the above-mentioned conventional method, during the charging operation, that is, while the inverter switching circuit is switching, the comparator detects the charging voltage and the voltage command value as 10 [V]. Since the end of charging is detected by comparing with a low voltage signal of a certain degree, the control accuracy of the charging voltage becomes low due to the influence of the switching noise of the inverter switching circuit. Further, this noise countermeasure requires a high level of technology, which increases the cost.

The present invention has been made in view of the above-mentioned circumstances, and simplifies noise countermeasures and improves control accuracy of charging voltage.
An object of the present invention is to provide a charging voltage control circuit that can reduce the cost by reducing the size of the entire device.

[0012]

A charging voltage control circuit according to the present invention comprises a voltage detection value obtained by dividing a charging voltage by a predetermined voltage dividing ratio and a voltage command value obtained by converting the charging voltage command value by the voltage dividing ratio. An arithmetic means for calculating the number of switching times required for charging, an analog / digital conversion means for converting the number of switching times calculated by this arithmetic means from an analog value into a digital value, and the number of switching times up to the number of switching times calculated by the above arithmetic means. It is characterized by comprising a counting means for counting and a flip-flop circuit for outputting a command signal corresponding to an operation command for starting or stopping the driving of the switching based on the counting means.

Further, the charging voltage control circuit further comprises a signal input means for inputting a command signal for starting the operation of the arithmetic means, the analog / digital converting means, the counting means and the flip-flop circuit, and the counter circuit. Signal output means for outputting a charge end signal indicating that the predetermined count operation has ended.

[0014]

The subtraction / division circuit calculates the number of switching times required to charge the high voltage capacitor to a predetermined voltage by inputting the voltage command value and the residual voltage detection value immediately before the start of charging. The A / D conversion circuit converts a switching number, which is an analog value output from the subtraction / division circuit, into a digital value when a command signal is input from the overall control circuit, and the switching number is input to a counter circuit. Preset. The counter circuit starts counting the number of times of switching up to the number of times of switching by receiving the command signal. The flip-flop circuit outputs a signal corresponding to an operation command for starting or stopping the switching operation of the inverter switching circuit to the drive circuit based on the preset number of times of switching in the counter circuit. When the charging operation ends, the counter circuit outputs a charging end signal to the overall control circuit.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration of a high-voltage pulse charging power supply to which the charging voltage control circuit according to the present invention is applied.

Alternating current is input to the rectifier circuit 2 from a commercial power source 1 of 50 Hz or 60 Hz, which is three-phase or single-phase. The rectifier circuit 2 converts the alternating current into direct current and supplies it to the direct current smoothing capacitor 3.

The inverter switching circuit 4 provided at the subsequent stage of the DC smoothing capacitor 3 is of a full bridge type using switching elements 4a to 4d such as high speed transistors or field effect transistors (FETs), and is composed of 4a, 4d and 4b. The switching elements according to the combination of 4c are simultaneously turned on or off for a predetermined time. Further, in the combination of the switching elements, the DC voltage of the DC voltage smoothing capacitor 3 is converted into a pulsed AC voltage by alternately turning on and off in a predetermined repeated synchronization. The generated pulsed AC voltage is boosted to a pulsed AC high voltage by the step-up transformer 5 having good high frequency characteristics. The high-voltage rectifier circuit 6 rectifies the pulsed AC high voltage, and charges the high-voltage capacitor 7 provided at the subsequent stage with a high-voltage pulse having a positive or negative predetermined polarity by its circuit configuration.

The voltage dividing resistor 8 provided in the subsequent stage of the high voltage capacitor 7 is composed of a series connection circuit of a high voltage side resistor 8a and a low voltage side resistor 8b, and has a charging voltage value charged in the high voltage capacitor 7 described above. It is a resistance voltage divider circuit for detection. The charging voltage charged in the high voltage capacitor 7 is divided into a low voltage by the voltage dividing resistor 8 and output to both ends of the low voltage side resistor 8b. Normally, one of the low voltage side resistors 8b is connected to the ground potential. The output voltage value V8b output across the low voltage side resistor 8b is input to the charging voltage control circuit 30.

The charging voltage control circuit 30 inputs the voltage command value Vref from the voltage dividing resistor 8 and the command signals S and P from the overall control circuit 20 to operate the drive circuit 11 the required number of times of switching to charge. At the end, the charge end signal EOC is output to the overall control circuit 20.

The overall control circuit 20 sends a voltage command value Vref to the charging voltage control circuit 30 by an operation or a command from the outside.
, The command signals S and P are output, and the drive circuit 1
A command for operating the inverter switching circuit is output to 1. The drive circuit 11 turns on or off the switching elements 4a to 4d of the inverter switching circuit 4 at a switching frequency of several tens KHz. Further, the overall control circuit 20 outputs a display or a predetermined signal to the outside by inputting the charging end signal EOS at the end of charging. The configuration of the charging voltage control circuit 30 is shown in FIG.

The charging voltage control circuit 30 includes a subtraction / division circuit 31, an A / D conversion circuit (analog / digital conversion circuit).
32, counter circuit 33, and flip-flop circuit 3
It is composed of 4. The subtraction / division circuit 31 inputs the voltage command value Vref and the residual voltage detection value V8b immediately before the start of charging to calculate the number of switching times required to charge the high voltage capacitor 7 to a predetermined voltage.

The A / D conversion circuit 32 is the entire control circuit 20.
When the command signal P is input, the number of times of switching, which is an analog value output from the subtraction / division circuit 31, is converted into a digital value. Similarly, the counter circuit 33
When the command signal P is input, the switching number is preset, and when the command signal S is input, the switching number counting operation is started up to the switching number and the charging operation is ended. A charge end signal EOC is output.

The flip-flop circuit 34 is provided after the counter circuit 33 and outputs a signal corresponding to an operation command for starting or stopping the switching operation of the inverter switching circuit 4 to the drive circuit 11. Next, the operation of the above embodiment will be described.

The overall control circuit 20 is controlled by an external operation or command to cause the subtraction / division circuit 3 of the charging voltage control circuit 30 to operate.
1 outputs the voltage command value Vref, the command signal P to the A / D conversion circuit 32 and the counter circuit 33, and outputs a signal for starting the operation of the inverter switching circuit 4 to the drive circuit 11.

The subtraction / division circuit 31 which receives the voltage command value Vref subtracts the residual voltage detection value V8b immediately before the charging of the high voltage capacitor 7 input from the voltage dividing resistor 8 from the voltage command value Vref. Then, the necessary and sufficient voltage is calculated. Further, this necessary and sufficient voltage is divided by the charging voltage increase value per switching determined by the circuit constant of the charging circuit to calculate the number of switching times required to charge the high voltage capacitor 7 to a predetermined voltage. The calculated number of times of switching is input to the A / D conversion circuit 32 in the state of an analog value.

The A / D conversion circuit 32 receives the command signal P as described above, and thereby converts the number of times of switching input as an analog value into a digital value. The number of switching times converted into a digital value is calculated by the A / D conversion circuit 32.
Similarly, the command signal P is preset in the input counter circuit 33.

After the command signal P is output from the overall control circuit 20, the command signal S is input to the charging voltage control circuit 30 again. The command signal S is input to the counter circuit 33 and the flip-flop circuit 34 of the charging voltage control circuit 30.

The flip-flop circuit 34 outputs a command signal corresponding to an operation command for causing the drive circuit 11 to start the switching operation of the inverter switching circuit 4 by the command signal S. At this point, the inverter switching circuit 4 operates and the charging operation is started.

The counter circuit 33 starts counting by the command signal S, and performs counting operation up to the required number of switching times calculated by the subtraction / division circuit 31.
When the required switching count is completed, the signal output to the flip-flop circuit 34 is inverted from the state up to then, and the operation of the drive circuit 10 is stopped and the switching operation of the inverter switching circuit 4 is stopped.

At this point, the charging operation is completed, and the counter circuit 33 of the charging voltage control circuit 30 outputs the charging end signal EOC.
Is output to the overall control circuit 20. Overall control circuit 20
When this charging end signal EOC is input, the display externally indicates the end of charging or outputs a predetermined signal.

As described above, since the calculation of the necessary number of times of switching, which is important for the control accuracy of the charging voltage, is performed without being affected by the switching noise before the switching is started, the charging voltage control accuracy can be improved.
The charging voltage control circuit according to the above-described embodiment can be configured using a microcomputer.

[0032]

As described above in detail, since the calculation of the number of times of switching necessary for charging, which is important for the accuracy of controlling the charging voltage, is performed without being affected by the switching noise before the switching is started, the accuracy of controlling the charging voltage is controlled. Can be improved. Further, the control during the switching operation is only the counting operation by the counter circuit, so that the noise countermeasure can be simplified and the downsizing cost of the entire apparatus can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a high-voltage pulse charging power supply by a charging voltage control circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a charging voltage control circuit according to the embodiment.

FIG. 3 is a block diagram showing a conventional high voltage pulse charging power supply circuit configuration.

FIG. 4A is a time chart showing a detected value of a charge voltage, and FIG. 4B is a time chart showing an output of a comparator in the conventional charge voltage control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 2 ... Rectifier circuit, 3 ... DC voltage smoothing capacitor, 4 ... Inverter switching circuit, 5 ... Step-up transformer, 6 ... High-voltage rectifier circuit, 7 ... High-voltage capacitor, 8
... voltage dividing resistor, 11 ... drive circuit, 20 ... overall control circuit, 30 ... charging voltage control circuit, 31 ... subtraction / division circuit,
32 ... A / D conversion circuit, 33 ... Counter circuit, 34 ... Flip-flop circuit

Claims (2)

[Claims] 1. A voltage detection value and a predetermined voltage obtained by dividing a charging voltage by a predetermined voltage division ratio in a charging voltage control circuit of a charging power supply circuit that executes a charging operation using a switching means that performs switching at a predetermined timing. An arithmetic means for calculating the number of times of switching by the switching means required to perform charging to the predetermined voltage value from the voltage command value obtained by converting the value by the voltage division ratio, and an analog value for the number of times of switching calculated by the arithmetic means. An analog / digital conversion means for converting into a more digital value, a counting means for counting the number of times of switching of the switching means up to the number of times of switching of the digital value, and an operation command for starting or stopping the driving of the switching means based on the counting means. Flip-flop that outputs a command signal corresponding to A charging voltage control circuit comprising: a drop circuit. 2. A signal input means for inputting a command signal for starting an operation to said arithmetic means, said analog / digital converting means, said counting means and said flip-flop circuit, and said counter circuit performs a predetermined counting operation. 2. A signal output means for outputting to the control means a charging end signal indicating that the charging has been completed.
The charging voltage control circuit according to.