JP2024168319A - Multi-level DC power supply - Google Patents

Abstract

To cancel an electric charge and an electrostatic energy accumulated to a capacitive load, and outputs a predetermined output voltage.SOLUTION: A multilevel DC power supply of the present invention, connects a bidirectional DC/DC converter to between a DC power supply and a pulse formation part. The bidirectional DC/DC converter executes a DC voltage conversion of converting into a DC voltage of a voltage level that is different from a voltage value of the DC power supply; and a DC voltage conversion of converting the EC voltage of the pulse formation part into a regenerative voltage, and forms a pulse voltage of a multi level of which an output level is different, and regenerates a residual DC voltage of the pulse formation part as a regenerative voltage to the DC power supply.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multilevel DC power supply that outputs DC pulse voltages with different output levels.

Multilevel DC power supplies are known that output DC pulse voltages of different output levels to a load. For example, in fields such as semiconductor processing, pulsed DC power is applied to a high-frequency plasma device that processes and processes objects using high-frequency plasma.

Patent Document 1 describes a multilevel power supply that includes two power sources, a power source that supplies a first potential _V1 and a power source that supplies a second potential _V2 , and a switching mechanism including switching elements Q1 and Q2, and discloses a configuration in which the output level is switched by changing the switching state of the switching mechanism.

Patent document 2 discloses a power conversion device that includes one DC power source and multiple DC/DC converters connected in parallel, and controls the output power according to the drive state of these DC/DC converters.

Figure 4 shows an example of the configuration of a multilevel DC power supply consisting of one DC power supply and multiple DC/DC converters. Multilevel DC power supply 100 includes DC/DC converter 101A, DC/DC converter 101B, and control unit 102. DC/DC converter 101A and DC/DC converter 101B have different output voltages, and control unit 102 switches between DC/DC converter 101A and DC/DC converter 101B to supply different voltages to load 103.

JP 2016-7134 A Patent No. 6771700

In a configuration with multiple DC/DC converters, the number of DC power supplies can be reduced to one. Although the number of components increases with the addition of DC/DC converters, the total size of the multilevel DC power supply is reduced because DC/DC converters are smaller than DC power supplies.

When a pulse voltage is supplied to a load, the output voltage may deviate from a predetermined voltage due to charges or electrostatic energy accumulated in the capacitive load.
5A and 5B show the state of the output voltage switching between a low voltage and a high voltage. In the configuration of the multilevel DC power supply shown in Fig. 4, when DC/DC converter 101A is used as a converter for low voltage and DC/DC converter 101B is used as a converter for high voltage, DC/DC converter 101A outputs output voltage V1 of low output in response to switching signal Si_low, and DC/DC converter 101B outputs output voltage V2 of high output in response to switching signal Si_High.

When charge or electrostatic energy accumulates in the capacitive load, the output voltage rises with each pulse output, causing a deviation from the low output voltage V1, and the specified output voltage cannot be obtained. V_low1 and V_low2 in Figure 5B indicate output voltages that deviate from the low output output voltage V1. Note that the waveform in Figure 5B is shown diagrammatically and does not represent the actual voltage waveform.

The present invention aims to solve the above-mentioned problems of the conventional technology, eliminate the charge and electrostatic energy accumulated in the capacitive load, and output a predetermined output voltage.

The multilevel DC power supply of the present invention connects a bidirectional DC/DC converter between the DC power supply and the pulse forming section. The bidirectional DC/DC converter performs DC voltage conversion to convert the voltage value of the DC power supply to a DC voltage of a different voltage level, and DC voltage conversion to convert the DC voltage of the pulse forming section to a regenerative voltage, forming multilevel pulse voltages with different output levels, and regenerating the excess DC voltage of the pulse forming section to the DC power supply as a regenerative voltage.

The multilevel DC power supply of the present invention comprises a DC power supply that outputs a DC voltage, a pulse forming unit that forms a pulse voltage, and a bidirectional DC/DC converter connected between the DC power supply and the pulse forming unit.

The bidirectional DC/DC converter performs bidirectional DC voltage conversion in different current directions. The first-direction DC voltage conversion converts the DC voltage of the DC power supply to a DC voltage with a different voltage level, which is output to the pulse forming section. The second-direction DC voltage conversion converts the voltage of the pulse forming section into a regenerative voltage that is regenerated to the DC power supply, and is regenerated to the DC power supply.

The pulse forming unit switches between the DC voltage of the DC power supply and the output voltage of the bidirectional DC/DC converter to form a multi-level pulse voltage with different output levels.

The DC voltage of the DC power supply and the DC voltage output by the bidirectional DC/DC converter have different voltage levels. This allows the pulse forming unit to form a multi-level pulse voltage with different voltage levels.

The bidirectional DC/DC converter of the present invention outputs a multilevel pulse voltage by DC voltage conversion in a first direction. With this configuration, the multilevel DC power supply of the present invention can be configured with a single bidirectional DC/DC converter without requiring multiple DC power supplies or multiple DC/DC converters, allowing the power supply device to be made smaller.

The bidirectional DC/DC converter of the present invention also converts excess voltage due to charge and electrostatic energy accumulated in the capacitive load into a regenerative voltage that is regenerated to the DC power supply by DC voltage conversion in the second direction, and regenerates the excess energy to the DC power supply. With this configuration, the charge and electrostatic energy accumulated in the capacitive load are eliminated, the voltage level of the pulse voltage can be maintained at a predetermined voltage, and the excess energy can be reused by regenerating it to the DC power supply.

(additional capacitor)
The multilevel DC power supply of the present invention comprises a first capacitor and a second capacitor.
The first capacitor has one end connected to the output terminal of the DC power supply and the other end grounded, and the second capacitor has one end connected to the output terminal of the bidirectional DC/DC converter and the other end grounded. The second capacitor can be provided inside or outside the bidirectional DC/DC converter.
The first capacitor suppresses voltage fluctuations in the power supply line from the DC power supply and replenishes power to the load, while the second capacitor smoothes voltage ripples in the output voltage of the bidirectional DC/DC converter and suppresses fluctuations in the peak value of the pulse output.

(additional damping resistor)
The multilevel DC power supply of the present invention comprises a first damping resistor and a second damping resistor.
The first damping resistor is connected between the DC power supply and the pulse forming unit, and the second damping resistor is connected between the bidirectional DC/DC converter and the pulse forming unit. The first damping resistor and the second damping resistor suppress overshoot included in the DC voltage.

(Output detection section and control section)
The multilevel DC power supply of the present invention includes an output detection section that detects the output of the pulse forming section, and a control section that controls the DC power supply and the bidirectional DC/DC converter.
The control unit performs feedback control based on the detection value of the output detection unit. The feedback control includes a voltage level control and a switching control.
The voltage level control controls the voltage level of the DC voltage of the DC power supply based on the detection value of the output detection unit, and the switching control controls switching of the voltage conversion direction of the bidirectional DC/DC converter.

As described above, the multilevel DC power supply of the present invention can eliminate the charge and electrostatic energy accumulated in the capacitive load and output a predetermined output voltage.

FIG. 1 is a diagram for explaining a configuration example of a multilevel DC power supply according to the present invention. 4 is a flowchart for explaining an example of the operation of the multilevel DC power supply of the present invention. 4 is a signal diagram for explaining an example of the operation of the multilevel DC power supply of the present invention. FIG. 1 is a diagram for explaining the configuration of a conventional multilevel DC power supply. 1 is a diagram for explaining an example of an output voltage of a multilevel DC power supply;

(1) Schematic Configuration of the Multilevel DC Power Supply of the Present Invention The schematic configuration of the multilevel DC power supply (direct current power supply) of the present invention will now be described with reference to FIG.
1 shows an example of a configuration in which two voltage levels, a LOW output and a HIGH output, are output to a load 20. In this configuration, a capacitive load such as a plasma load is shown as an example of the load 20. As an example of the two voltage levels supplied to the capacitive load, the LOW output is a negative voltage of -2000V, and the HIGH output is a negative voltage of -900V.

The multilevel DC power supply 1 of the present invention comprises a DC power supply 2 that outputs a DC voltage, a pulse forming unit 4 that forms a pulse voltage, and a bidirectional DC/DC converter 3 connected between the DC power supply 2 and the pulse forming unit 4.

The DC power supply 2 is configured using an AC/DC converter that converts AC to DC, or a battery. The DC power supply 2 in the configuration example shown in Fig. 1 outputs a negative voltage for a LOW output.
A first capacitor 7 is connected to the output end of the DC power supply 2. The first capacitor 7 suppresses voltage fluctuations in the power supply line connected to the output end of the DC power supply 2, and supplements the power supplied to the load.

The bidirectional DC/DC converter 3 is a converter that converts DC voltage in both directions between the power supply side and the load side, and is used as a step-up/step-down converter that steps up the voltage in one direction and steps down the voltage in the other direction.

The bidirectional DC/DC converter 3 converts the DC output voltage V1 of the LOW output of the DC power supply 2 to the DC output voltage level of the HIGH output of the DC output voltage V2 by DC voltage conversion in the first direction from the DC power supply 2 to the pulse forming unit 4, and outputs it to the pulse forming unit 4. The bidirectional DC/DC converter 3 also converts the voltage of the pulse forming unit 4 to a regenerative voltage that is regenerated to the DC power supply 2 by DC voltage conversion in the second direction from the pulse forming unit 4 to the DC power supply 2, and regenerates it to the DC power supply 2.

Here, the DC output voltage V1 of the LOW output and the DC output voltage V2 of the HIGH output are negative voltages, and the absolute value of the output voltage V2 is smaller than the absolute value of the output voltage V1. In this case, in the DC voltage conversion in the first direction, the DC voltage conversion that converts the voltage level from the output voltage V1 to the output voltage V2 corresponds to a negative step-down, and in the DC voltage conversion in the second direction, the DC voltage conversion of the regenerative voltage regenerated in the DC power supply 2 corresponds to a negative step-up.

A second capacitor 8 is connected to the output end of the bidirectional DC/DC converter 3. The second capacitor 8 may be built into the bidirectional DC/DC converter 3, or may be connected to a line connecting the output end of the bidirectional DC/DC converter 3 and the pulse forming unit 4. The second capacitor 8 smoothes the voltage ripple contained in the output voltage of the bidirectional DC/DC converter.

The pulse forming unit 4 inputs the DC output voltage V1 of the DC power supply 2 and the DC output voltage V2 of the bidirectional DC/DC converter 3, switches between either DC voltage by switching operation, and outputs it as a pulse voltage. The switching operation is performed by switching the switching element of the bidirectional DC/DC converter 3 with an external pulse signal. The pulse forming unit 4 forms a multilevel pulse voltage with different output levels by this switching operation, and supplies it to the load 20. The multilevel DC power supply 1 of the configuration example shown in FIG. 1 outputs a pulse voltage of two voltage levels, the DC output voltage V1 of the LOW output and the DC output voltage V2 of the HIGH output, but the voltage level of the pulse voltage is not limited to two voltage levels and can be three or more voltage levels.

A first damping resistor is connected between the DC power supply 2 and the pulse forming unit 4, and a second damping resistor is connected between the bidirectional DC/DC converter 3 and the pulse forming unit 4. The first damping resistor and the second damping resistor suppress overshoots contained in the DC output voltage V1 output from the DC power supply 2 and the DC output voltage V2 output from the bidirectional DC/DC converter 3.

Furthermore, the multilevel DC power supply 1 of the present invention includes an output detection unit 6 that detects the output voltage Vout of the pulse forming unit 4, and a control unit 5 that controls the DC power supply 2 and the bidirectional DC/DC converter 3.

The control unit 5 performs feedback control based on the detection value of the output detection unit 6. The feedback control of the control unit 5 includes voltage level control and switching control.

The voltage level control controls the voltage level of the DC voltage of the DC power supply 2 based on the output voltage Vout detected by the output detection unit 6. The detected value is compared with a set voltage, and if the detected value deviates from the set voltage, feedback control is performed so that the voltage level of the DC voltage output from the DC power supply 2 becomes the set voltage.

The switching control controls switching of the voltage conversion direction of the bidirectional DC/DC converter 3 .
The switching control compares the output voltage Vout of the output detection unit 6 with the DC output voltage of the HIGH output, and switches between an output operation in which a HIGH output is output to the pulse forming unit 4, and a regenerative operation in which the voltage of the pulse forming unit 4 is converted into a regenerative voltage Vre and regenerated to the DC power supply 2.

(2) Example of Operation of the Multilevel DC Power Supply of the Present Invention An example of operation of the multilevel DC power supply of the present invention will be described with reference to the flow chart and signal diagram of Fig. 2. Note that an example of operation for outputting pulse voltages of two voltage levels, LOW output and HIGH output, is shown here.

The external pulse signal is a Low signal that controls the output of a Low output and a High signal that controls the output of a High output in the switching operation of the pulse forming section 4 .
When the pulse forming unit 4 receives a low signal for output control of the low output (S1), it switches the low-side switching element SW_low to the on state and switches the high-side switching element SW_high to the off state (S2). By switching the switching elements to the state (S2), the pulse forming unit 4 outputs the direct current output voltage V1 at the low output output from the DC power supply 2 as the output voltage Vout (S3).

The output detection unit 6 detects the output voltage Vout of the pulse formation unit 4 and feeds back the detection value to the control unit 5. The control unit 5 judges whether the detection value of the fed back output voltage Vout is within the normal range of the DC output voltage V1 of the LOW output. The output voltage Vout is judged by comparing the detection value with the allowable range of the set voltage set as the normal output voltage, and if the detection value is within the allowable range, it is judged to be in a normal state, and if it is outside the allowable range, it is judged to be in an abnormal state (S4).

If it is determined that the detected value is within the allowable range, the output state of the DC power supply 2 is maintained. If it is determined that the detected value is outside the allowable range, the control unit 5 performs voltage control so that the output voltage V1 of the DC power supply 2 becomes the set voltage (S5).

When the pulse forming unit 4 receives a high signal that controls the output of the high output (S1), it switches the high-side switching element SW_low to the off state and switches the high-side switching element SW_high to the on state (S6). By switching the switching elements to the state (S6), the pulse forming unit 4 outputs the DC output voltage V2 at the high output output from the bidirectional DC/DC converter 3 as the output voltage Vout (S7).

The output detection unit 6 detects the output voltage Vout of the pulse forming unit 4 and feeds back the detected value to the control unit 5. The control unit 5 compares the fed back detection value of the output voltage Vout with the DC output voltage V2 of the HIGH output (S8).

When the detected value of the output voltage Vout is within the allowable range of the DC output voltage V2 of the HIGH output, it is determined whether the bidirectional DC/DC converter 3 is in regenerative operation (S9), and if it is in regenerative operation, the bidirectional DC/DC converter 3 is switched from regenerative operation to output operation (S10), and if it is in output operation, the output operation of the bidirectional DC/DC converter 3 is maintained (S1).

When the detected value of the output voltage Vout is higher than the DC output voltage V2 of the HIGH output and has a large absolute value in the negative direction (S8), the bidirectional DC/DC converter 3 is switched from output operation to regeneration operation (S11).

Figure 3A shows the external pulse signal, Figure 3B shows the output voltage, Figure 3C shows the regenerative operation control signal, and Figure 3D shows the output operation control signal.

In the external pulse signal, "LOW" is a signal that switches the switching element of the pulse forming unit 4 to output a LOW output, and "HIGH" is a signal that switches the switching element of the pulse forming unit 4 to output a HIGH output.

When the external pulse signal falls and switches to "LOW" at "P1" in Figure 3A, the output voltage in Figure 3B changes from the HIGH output voltage V2 to the LOW output voltage V1, and a LOW output pulse voltage is output.

When the external pulse signal rises and switches to "HIGH" at "P2" in Figure 3A, the output voltage in Figure 3B changes from the LOW output voltage V1 to the HIGH output voltage V2, and a pulse voltage of the HIGH output output voltage V2 is output.

When a charge is stored in the capacitive load during a LOW output, if the stored charge is not fully discharged, when the output voltage changes from LOW output V1 to HIGH output V2, the voltage becomes Va, which is between the output voltage V1 and the output voltage V2, without decreasing in the negative direction to the output voltage V2. "Q4a" in Figure 3B shows this voltage state.

The control unit 5 detects this voltage state by feedback of the output voltage Vout, and causes the bidirectional DC/DC converter 3 to perform regenerative operation using the regenerative operation control signal Si_re (Fig. 3C). The LOW output voltage drops in the negative direction from voltage Va toward "Q4b" of the HIGH output output voltage V2 due to the regenerative operation. When the LOW output voltage reaches the HIGH output output voltage V2, the control unit 5 switches the bidirectional DC/DC converter 3 from regenerative operation to output operation using the output operation control signal Si_out (Fig. 3D).

(3) Another Configuration of the Multilevel DC Power Supply of the Present Invention The configuration example of the multilevel DC power supply shown in Fig. 1 is a configuration example that outputs two power levels, HIGH output and LOW output. The multilevel DC power supply of the present invention is not limited to two voltage levels, HIGH output and LOW output, but may be a multilevel with three or more voltage levels. For example, in the case of three power levels, the HIGH output may be configured with two power levels, HIGH1 and HIGH2, and one power level, LOW output.

The multilevel DC power supply of the present invention can be applied to high-frequency power supplies (RF generators) used in semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, etc.

1 Multilevel DC power supply 2 DC power supply 3 Bidirectional DC/DC converter 4 Pulse forming section 5 Control section 6 Output detection section 7 First capacitor 8 Second capacitor 9 First damping resistor 10 Second damping resistor 20 Load 100 Multilevel DC power supply 102 Control section 103 Load Low, High1, High2 External pulse signal SWhigh Switching element SWlow Switching elements Si_low, Si_high Switching signal Si_re Regenerative operation control signal Si_out Output operation control signal V1, V2, V3 Output voltage Vout Output voltage Vre Regenerative voltage

Claims (1)

A DC power supply that outputs a DC voltage;
A pulse forming unit that forms a pulse voltage;
a bidirectional DC/DC converter connected between the DC power supply and the pulse forming unit;
The bidirectional DC/DC converter comprises:
a first-direction DC voltage conversion for converting the DC voltage of the DC power source into a DC voltage of a different voltage level and outputting the converted DC voltage to the pulse forming unit;
A second direction DC voltage conversion is performed by converting the voltage of the pulse forming unit into a regenerative voltage that is regenerated to a DC power source, and the regenerative voltage is converted to a DC power source in the second direction.
Run
The pulse forming unit includes:
A DC voltage of the DC power supply and an output voltage of the bidirectional DC/DC converter are switched to form a multi-level pulse voltage having different output levels.
Multi-level DC power supply.

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