JP2023045318A - Power supply device - Google Patents

Abstract

To easily reduce a voltage to ground generated between elements, without deteriorating filter characteristics.SOLUTION: A class D amplifier 10 includes: a full bridge switching circuit 13 that has a pair of output terminals and that converts DC power to AC power by PWM control; a filter circuit 14A that has inductors L1 to Lm as a first element connected in series and capacitors C1 to Cn as a second element and that has one end connected to one of the output terminals of the full bridge switching circuits 13; and a transformer 15 with one end connected to the other end of the filter circuit 14A and the other end connected to the other output terminal of the full bridge switching circuit 13. In the filter circuit 14A, the first element and the second element are alternately arranged.SELECTED DRAWING: Figure 3

Description

The present invention relates to a power supply device.

2. Description of the Related Art Conventionally, a high-frequency power supply (simply referred to as a power supply) that supplies high-frequency power to a load such as a plasma load is known. Such a high-frequency power supply uses, for example, a class D amplifier, and converts a DC voltage into an AC voltage to supply AC power (high-frequency power) to a load. A class D amplifier has a voltage conversion circuit that converts a DC voltage into a square-wave differential voltage by the switching operation of switching elements. In addition, a filter circuit, a transformer, and the like functioning as a resonance circuit are provided at the subsequent stage of the voltage conversion circuit, and convert the differential voltage into a sine wave voltage and output it. An LC filter including an inductor L (coil L) and a capacitor C (capacitor C) is generally used for the filter circuit. The output frequency of the high-frequency power supply is, for example, an industrial RF band (Radio Frequency) such as 13.56 MHz, 27.12 MHz, or 40.68 MHz.

JP-A-2003-143861 JP 2017-054646 A JP 2018-057223 A

Generally, the characteristics of this LC filter are represented by the following equation.
Q=2πfL/R _pri (R _pri : Apparent load resistance value on the primary side)

That is, the larger the Q value, the better the filter characteristics, but the voltage applied to the inductor L and the capacitor C increases in proportion to the Q value, as shown in the following equation.
|V _C |=|V _L |=Q|V _Rpri |

In this case, the voltage VC applied to the capacitor _C and the voltage VL applied to the inductor _L have phases that cancel each other out.

However, a voltage before being canceled is applied to the wiring between the inductor L and the capacitor C,
Voltage Q|V _Rpri |
is applied as is. Therefore, the voltage to ground generated between LC was supposed to rise. Therefore, there is a risk that the size of the device will increase and structural restrictions will arise due to the need to ensure insulation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to easily reduce the voltage to ground generated between elements without deteriorating filter characteristics.

A power supply device according to the present embodiment has a pair of output terminals, a voltage conversion circuit that converts a DC voltage to an AC voltage, and an inductor as a first element and a capacitor as a second element that are connected in series. and a filter circuit having one end connected to one of the output terminals of the voltage conversion circuit, one end connected to the other end of the filter circuit, and the other end connected to the other output terminal of the voltage conversion circuit. and a transformer, wherein m×n≧ 2, and when the inductance set in the filter circuit is LL0 and the capacitance is CC0, the inductances of the m first elements are LL1, LL2, LL3, . the capacitances of the second elements are CC1, CC2, CC3, . . . , CCn, respectively;
LL1+LL2+LL3+...+LLm=LL0
1/CC1+1/CC2+1/CC3+...+1/CCn=1/CC0
In the filter circuit, the first elements and the second elements are alternately arranged.

According to the above configuration, as compared with the case where the filter circuit is configured with one first element and one second element, the It is possible to reduce the voltage to ground generated in (wiring between elements).

Further, in the filter circuit, when the number of the first elements is two or more, all the first elements have the same inductance, and when the number of the second elements is two or more, the second elements are All have the same capacitance.

According to the above configuration, the voltage applied to the first element can be evenly lowered, and the voltage applied to the second element can be evenly lowered. The voltage between the element and the second element can be lowered evenly.

According to the embodiment, it is possible to reduce the voltage to ground generated between elements (inter-element wiring) without deteriorating filter characteristics.

FIG. 1 is a schematic configuration block diagram of a class D amplifier. FIG. 2 is an explanatory diagram of the essential configuration of a conventional class D amplifier. FIG. 3 is an explanatory diagram of the first embodiment. FIG. 4 is an explanatory diagram of a first specific example of the first embodiment. FIG. 5 is an explanatory diagram of a second specific example of the first embodiment. FIG. 6 is an explanatory diagram of the second embodiment. FIG. 7 is an explanatory diagram of a first specific example of the second embodiment. FIG. 8 is an explanatory diagram of a second specific example of the second embodiment. FIG. 9 is an explanatory diagram of the third embodiment. FIG. 10 is an explanatory diagram of a specific example of the third embodiment.

Next, embodiments will be described with reference to the drawings.
FIG. 1 is a schematic configuration block diagram of a class D amplifier.
The class D amplifier 10 includes a PWM circuit 11 , a gate driver section 12 , a full bridge switching circuit 13 , an LC filter (low pass filter) 14 , a transformer 15 and a DC power supply section 16 .

The PWM circuit 11 generates a PWM control signal SPWM and outputs it to the gate driver section 12 .
The gate driver section 12 outputs gate drive signals GD1 to GD4 to be supplied to the gate terminals of the transistors forming the full bridge switching circuit 13 based on the PWM control signal.

The full bridge switching circuit 13 is driven based on gate drive signals GD1-GD4.
The LC filter 14 is composed of m inductors and n capacitors, and the inductors and capacitors are alternately connected in series.
Here, m is a natural number of 1 or more, n is a natural number of 1 or more, and m×n≧2.

Also, one (one) inductor does not physically indicate one inductor, and for example, when two inductors are directly connected, it is regarded as one inductor. Similarly, one (one) capacitor does not physically indicate one capacitor. For example, when two capacitors are directly connected, they are regarded as one capacitor.

Therefore, when they are connected in the order inductor->inductor->capacitor->inductor, it is considered that one inductor, one capacitor, and one inductor are connected in series. Also, when they are connected in the order of capacitor->capacitor->inductor->inductor->inductor->capacitor, it is considered that one capacitor, one inductor and one capacitor are connected in series. The same applies to the following embodiments.

Further, when connecting an inductor and a capacitor in series, if the inductor is used as the first element and the capacitor is used as the second element, either one of the first element and the second element However, the portion sandwiched between the other pair of elements is included. In this case, placing one element between any one of a pair of elements refers to the state in which three elements are connected in series in the order of one element - the other element - one element Say. For example, when one element is an inductor and the other element is a capacitor, it is a state of being connected in series in the order of inductor-capacitor-inductor, one element being a capacitor and the other element being an inductor. , it means that they are connected in the order of capacitor-inductor-capacitor.
Furthermore, the inductor (first element) and the capacitor (second element) are arranged alternately so that the applied voltage fluctuation can be canceled out because the applied voltage fluctuation is in the opposite direction. The same applies to the following embodiments.

The transformer 15 transforms the voltage applied to the primary side coil according to the turns ratio of the primary side coil and the secondary side coil, and supplies it to the load LD.

The DC power supply unit 16 supplies power to the load LD via the full bridge switching circuit 13 . In the following description, it is assumed that a power supply circuit (not shown) supplies power for operating each part of the class D amplifier 10 .

First, prior to explaining the operation of the embodiment, the problems of the conventional class D amplifier will be explained.
FIG. 2 is an explanatory diagram of the essential configuration of a conventional class D amplifier.
In FIG. 2, parts similar to those in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 2A, the full bridge switching circuit 13 constitutes a first upper arm, a first upper transistor TU1 whose gate terminal receives a gate drive signal GD1, and a second upper arm. A second upper transistor TU2 having a gate terminal to which a gate driving signal GD2 is input, a first lower transistor TU3 constituting a first lower arm and having a gate terminal to which a gate driving signal GD3 is input, and a second lower arm. and a second lower transistor TU4 having a gate terminal to which a gate drive signal GD4 is input.

In this case, a parasitic diode is formed between the drain terminal and the source terminal of each of the transistors TU1-TU4.

The LC filter 14P includes an inductor L0 and a capacitor C0 connected in series with the inductor L0. This LC filter 14P functions as a resonance circuit.

In the above configuration, the full-bridge switching circuit 13 generates a square-wave differential voltage by switching the DC power supplied from the DC power supply unit 16, and the LC filter detects harmonic components (especially the third harmonic and the fifth harmonic). wave) is removed and supplied to the transformer 15 as a sine wave voltage (AC voltage).

The transformer 15 transforms the sinusoidal voltage applied to the primary side coil according to the ratio of the number of turns of the primary side coil and the number of turns of the secondary side coil, and is configured as a plasma device or the like. It feeds the load LD.

Here, general characteristics of LC filters are described.
Generally, it is said that the larger the value of Q (Quality Factor) shown below, the better the filter characteristics of the LC filter.

However, the voltage V _L applied to inductor L0 and the voltage V _C applied to capacitor C0 rise in proportion to the value of Q, as shown by the following equations.

In this case, the phase of the voltage V _L and the phase of the voltage V _C are phases that cancel each other.

is applied as is. Therefore, the voltage to ground generated between inductor L0 and capacitor C0 increases.

More specifically, when the voltage V_HV0 in the wiring between the inductor L0 and the capacitor C0 forming the LC filter 14P is obtained by a circuit simulator, as shown in FIG. It can be seen that at time t1 and time t2, the voltage V_HV0 on the wiring between inductor L0 and capacitor C0 becomes a high voltage.

Since the DC power supply unit 16 and the LC filter 14P are not grounded, the potential at the position of the LC filter 14P is uncertain. Therefore, the center of the amplitude of the output waveform of the full-bridge switching circuit 13 may not be 0 volts. Therefore, the conditions of the circuit simulator are set so that the amplitude center of the output waveform of the full-bridge switching circuit 13 becomes an AC waveform with 0 volts. In the following, each condition is compared using the peak value of the voltage (hereinafter referred to as peak value) in the simulation results, taking into account the above. In addition, it demonstrates using a voltage peak-peak value (henceforth a peak-peak value) as needed.

In the example of FIG. 2B, when the output voltage of the DC power supply unit 16 is 400 volts and the turns ratio of the transformer 15 is 1:2, the peak value of the voltage V_HV0 is approximately 2,440 volts. At this time, since the voltage on the secondary side of the transformer 15 has a peak value of about 1,010 volts, it can be seen that the voltage V_HV0 is a high voltage. As a result, from the viewpoint of ensuring insulation, there is a possibility that the size of the device will increase and that there will be structural restrictions.

Therefore, in the following embodiments, it is an object to suppress the voltage to ground generated between the inductor and the capacitor without degrading the filter characteristics.

[1] First Embodiment FIG. 3 is an explanatory diagram of the first embodiment.
In FIG. 3, parts similar to those in FIGS. 1 and 2 are denoted by the same reference numerals.

In the following description, m is the number of series-connected inductors forming the LC filter, and n is the number of series-connected capacitors. Here, m and n are natural numbers of 1 or more, and m×n≧2.

In the LC filter 14A of FIG. 3, m=n-1.
Also, the LC filter 14A shown in FIG. 3 will be described as having the same characteristics as the LC filter 14P shown in FIG.

That is, when the inductances of inductors L1 to Ln-1 are assumed to be inductances LL1 to LL(n-1), the relationship between inductor L0 and inductance LL0 is as follows.
LL0=LL1+LL2+...+LL(n-2)+LL(n-1)

When the capacitances of the capacitors C1 to Cn are CC1 to CCn, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2+...+1/CC(n-1)+1/CCn

First, a first specific example of the first embodiment will be described.
FIG. 4 is an explanatory diagram of a first specific example of the first embodiment.
Here, for ease of understanding, a case of m=n−1=1 (one inductor and two capacitors) will be described in detail as an example.

In FIG. 4, the same reference numerals are given to the same parts as in FIG.
4 differs from FIG. 2 in that a capacitor C1 connected to the front stage of the inductor L0 and a capacitor C2 connected to the rear stage of the inductor L0 are provided instead of the capacitor C0.
In FIG. 4, the capacitor C1, the inductor L0, and the capacitor C2 are positioned between one of the pair of elements (here, the capacitor as the second element) and the other one element (here, the second element). 1 element (inductor) is arranged.

In this case, as described above, when the capacitances of the capacitors C1 and C2 are defined as the capacitances CC1 and CC2, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2

For example, 2·CC0=CC1=CC2 satisfies the above equation.

In the above example, the capacitances of the capacitors C1 and C2 are the same, and the capacitors C1 and C2 are connected in series via the inductor L0. Assuming that the voltage applied to C1 is V1 and the voltage applied to capacitor C2 is V2, the following is obtained.

V1=V2=V·CC2/(CC1+CC2)
=V·CC1/(CC1+CC2)

On the other hand, since the voltage Vc applied to the capacitor C0 shown in FIG. 2 is equal to V, the voltage V1 applied to the capacitor C1 and the voltage V2 applied to the capacitor C2 are lower than in the conventional example. I understand.

When the voltage V_HV1 in the wiring between the inductor L0 and the capacitor C1 constituting the LC filter 14B is obtained by a circuit simulator, as shown in FIG. At time t2, the voltage V_HV1 on the wire between inductor L0 and capacitor C1 rises, but remains at a very low voltage (approximately 2,440 volts peak) compared to the case of FIG. In the example of FIG. 4B, the peak value is about 1,425 volts).

Similarly, when the voltage V_HV2 in the wiring between the inductor L0 and the capacitor C2 forming the LC filter 14B is obtained by a circuit simulator, the transistors TU1 to TU4 are switched as shown in FIG. 4(B). At time t1 and time t2, the voltage V_HV2 on the wiring between inductor L0 and capacitor C2 rises, but is significantly lower than in the case of FIG. 4(B), the peak value is about 1,425 volts).

Next, a second specific example of the first embodiment will be described.
FIG. 5 is an explanatory diagram of a second specific example of the first embodiment.
Here, for ease of understanding, the case of m=n−1=2 will be specifically described as an example.
In FIG. 5, parts similar to those in FIG. 2 are given the same reference numerals.

5 differs from FIG. 2 in that the LC filter 14C includes capacitors C1, C2, and C3 instead of capacitor C0, inductors L1 and L2 instead of inductor L0, and capacitor C1→ The point is that they are connected in series in the order of inductor L2→capacitor C2→inductor L2→capacitor C3.

Further, in FIG. 5, the capacitor C1, the inductor L1 and the capacitor C2 portion, the capacitor C2, the inductor L2 and the capacitor C3 portion are each one of the pair of elements (here, the capacitor which is the second element). This is the place where one of the other elements (in this case, the inductor, which is the first element) is arranged between them.

Similarly, the inductor L1, capacitor C2, and inductor L2 portions are placed between one of the pair of elements (here, the inductor that is the first element) and the other one element (here, the second element). (capacitor) is arranged.
These are the same for other embodiments below.

In this case, when the capacitances of the capacitors C1, C2, and C3 are set to the capacitances CC1, CC2, and CC3 as described above, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2+1/CC3
For example, 3·CC0=CC1=CC2=CC3 satisfies the above equation.

In the above example, the capacitances of capacitors C1, C2, C3 are the same, and capacitors C1, C2, and C3 are connected in series via inductors L1 and L2, so that the total capacitance of capacitors C1, C2 is Let V be the applied voltage, V1 be the voltage applied to the capacitor C1, V2 be the voltage applied to the capacitor C2, and V3 be the voltage applied to the capacitor C3.

V1=V2=V3=V·CC1/(CC1+CC2+CC3)
=V·CC2/(CC1+CC2+CC3)
=V·CC3/(CC1+CC2+CC3)

In this case, since the voltage Vc applied to the capacitor C0 shown in FIG. 2 is Vc=V, the voltage V1 applied to the capacitor C1, the voltage V2 applied to the capacitor C2, and the voltage V3 applied to the capacitor C3 are , is lower than in the case of the conventional example.

On the other hand, as described above, when the inductances of the inductors L1 and L2 are assumed to be the inductances LL1 and LL2, the relationship between the inductor L0 and the inductance LL0 is as follows.
LL0=LL1+LL2
For example, LL0/2=LL1=LL2 satisfies the above equation.

In the above example, the inductors L1 and L2 have the same inductance magnitude, and the inductors L1 and L2 are connected in series via the capacitor C2. Let V10 be the voltage applied to inductor L1, V11 be the voltage applied to inductor L1, and V12 be the voltage applied to inductor L2.
V11=V12=V10/2

On the other hand, since the voltage V L applied to the inductor _L0 shown in FIG. 2 is V10, the voltage V11 applied to the inductor L1 and the voltage V12 applied to the inductor L2 are lower than in the conventional example. I understand.

The voltage V_HV1 in the wiring between the capacitor C1 and the inductor L1 that constitute the LC filter 14C, the voltage V_HV2 in the wiring between the inductor L1 and the capacitor C2, the voltage V_HV3 in the wiring between the capacitor C2 and the inductor L2, A voltage V_HV4 in the wiring between the inductor L2 and the capacitor C3 is obtained by a circuit simulator.

As a result, as shown in FIG. 5B, at time t1 or time t2 when the transistors TU1 to TU4 are switched, the voltage V_HV1 in the wiring between the capacitor C1 and the inductor L1 and the voltage V_HV1 in the wiring between the inductor L2 and the capacitor C3 Although the voltage V_HV4 on the wiring between them rises, the voltage V_HV2 on the wiring between the inductor L1 and the capacitor C2 and the voltage V_HV4 on the wiring between the capacitor C2 and the inductor L2 cancel each other out, and fluctuations are greatly suppressed. As a result, compared to the case of FIG. 2 (B) (about 2,440 volts at the peak value), the voltage is very low, less than half (about 1,084 volts at the peak value in the example of FIG. 5 (B)). It can be seen that

As described above, according to the first embodiment, compared with the conventional example, the filter characteristics are the same, that is, the voltage to ground generated between the inductor and the capacitor is reduced without deteriorating the filter characteristics. can be suppressed.

In the above description, the capacitor C0 is divided into two capacitors C1 and C2, and the capacitance of the capacitors C1 and C2 is double the capacitance of the capacitor C0. , the capacitor C0 is divided into X (X is a natural number of 3 or more) capacitors having the same capacitance, and the capacitance of the plurality of capacitors is X times the capacitance of the capacitor C0. can be suppressed.

In the above description, the LC filters 14A, 14B, and 14C are configured with capacitors having the same capacitance, but it is also possible to combine capacitors having different capacitances to function as a capacitor having a desired capacitance.

In this case, the voltage applied to the capacitor with the smallest capacitance defines the voltage to ground between the inductor and the capacitor. can be suppressed.

When the number of first elements (inductors) is two or more, the inductances of the first elements are all made the same. Also, when the number of second elements (capacitors) is two or more, the voltage can be most effectively suppressed by setting the capacitance of all the second elements to be the same. Of course, it is difficult to make the inductance and capacitance exactly the same, so the same inductance and capacitance should be used within the allowable error range. This also applies to the second embodiment and the like, which will be described later.

Also, in the above description, the full bridge switching circuit 13 is used as an example of the voltage conversion circuit, but the voltage conversion circuit is not limited to this. For example, other voltage conversion circuits such as half-bridge switching circuits can be used. This also applies to the second embodiment and the like, which will be described later.

[2] Second Embodiment FIG. 6 is an explanatory diagram of the second embodiment.
In FIG. 6, the same reference numerals are given to the same parts as in FIGS. 1 and 2 of the first embodiment.

In the second embodiment, the number m of inductors constituting the LC filter C is m=n+1 when expressed using the number n of capacitors.
Also, the LC filter 14D shown in FIG. 6 is described as having the same characteristics as the LC filter 14P shown in FIG.

That is, when the inductances of inductors L1 to Ln+1 are assumed to be inductances LL1 to LL(n+1), the relationship between inductor L0 and inductance LL0 is as follows.
LL0=LL1+LL2+...+LLn+LL(n+1)

When the capacitances of the capacitors C1 to Cn are CC1 to CCn, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2+...+1/CC(n-1)+1/CCn

Next, a first specific example of the second embodiment will be described.
FIG. 7 is an explanatory diagram of a first specific example of the second embodiment.
Here, for ease of understanding, the case of m=n+1=2 will be specifically described as an example.

In FIG. 7, parts similar to those in FIG. 2 are given the same reference numerals.
7 differs from FIG. 2 in that an inductor L1 connected to the front stage of the capacitor C0 and an inductor L2 connected to the rear stage of the capacitor C0 are provided instead of the inductor L0.

In this case, as described above, when the inductances of the inductors L1 and L2 are set to the inductances LL1 and LL2, the relationship between the inductor L0 and the inductance LL0 is expressed by the following equation.
LL0=LL1+LL2
For example, LL0/2=LL1=LL2 satisfies the above equation.

In the above example, the inductors L1 and L2 have the same inductance magnitude, and the inductors L1 and L2 are connected in series via the capacitor C0. Let V10 be the voltage applied to inductor L1, V11 be the voltage applied to inductor L1, and V12 be the voltage applied to inductor L2.
V11=V12=V10/2

On the other hand, since the voltage V L applied to the inductor L0 shown in FIG. ₂ is V, the voltage V11 applied to the inductor L1 and the voltage V12 applied to the inductor L2 are lower than in the conventional example. I know it will be.

When the voltage V_HV1 in the wiring between the capacitor C0 and the inductor L1 that constitute the LC filter 14E is obtained by a circuit simulator, the voltage in the wiring between the inductor L0 and the capacitor C1 is obtained as shown in FIG. V_HV1 is a very low voltage (approximately 1,240 volts peak in the example of FIG. 7B) compared to the case of FIG. 2B (approximately 2,440 volts peak). It can be seen that

Similarly, when the voltage V_HV2 in the wiring between the capacitor C0 and the inductor L2 forming the LC filter 14C is obtained by a circuit simulator, the voltage between the capacitor C0 and the inductor L2 is obtained as shown in FIG. Although the voltage V_HV2 on the wiring rises, it is very low (in the example of FIG. 7B, at a peak value of about 1,240 volts).

Next, a second specific example of the second embodiment will be described.
FIG. 8 is an explanatory diagram of a second specific example of the second embodiment.
Here, for ease of understanding, the case of m=n+1=3 will be specifically described as an example.
In FIG. 8, parts similar to those in FIG. 2 are given the same reference numerals.

8 differs from FIG. 2 in that, as the LC filter 14D, inductors L1, L2 and L3 are provided instead of inductor L0, capacitors C1 and C2 are provided instead of capacitor C0, and inductor L1→ The point is that they are connected in series in the order of capacitor C1→inductor L2→capacitor C2→inductor L3.

In this case, when the inductances of the inductors L1, L2, and L3 are set to the inductances LL1, LL2, and LL3 as described above, the relationship between the inductor L0 and the inductance LL0 is as follows.
LL0=LL1+LL2+LL3
That is, inductance LL1=LL0/3, inductance LL2=LL0/3, and inductance LL3=LL0/3.
For example, LL0/3=LL1=LL2=LL3 satisfies the above equation.

In the above example, inductors L1, L2, and L3 have the same inductance, and inductors L1, L2, and L3 are connected in series via capacitor C1 and capacitor C2. Let V10 be the voltage applied across L2 and L3, V11 be the voltage applied to inductor L1, and V12 be the voltage applied to inductor L2.
V11=V12=V13=V10/3

In this case, since the voltage V _L applied to the inductor L0 shown in FIG. 2 is V, the voltage V11 applied to the inductor L1, the voltage V12 applied to the inductor L2, and the voltage V13 applied to the inductor L3 is lower than that of the conventional example.

On the other hand, as described above, when the inductances of the capacitors C1 and C2 are the capacitances CC1 and CC2, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2
That is, the capacitance CC1=2.CC0 and the capacitance CC2=2.CC0.
For example, 2·CC0=CC1=CC2 satisfies the above equation.

In the above example, the capacitances of the capacitors C1 and C2 are the same, and the capacitors C1 and C2 are connected in series via the inductor L2. Assuming that the voltage applied to C1 is V1 and the voltage applied to capacitor C2 is V2, the following is obtained.
V1=V2=V·CC1/(CC1+CC2)
=V·CC2/(CC1+CC2)

In this case, since the voltage Vc=V applied to the capacitor C0 shown in FIG. 2, the voltage V1 applied to the capacitor C1, the voltage V3 applied to the voltage V2 applied to the capacitor C2, and It can be seen that it is lower than in the case of

The voltage V_HV1 in the wiring between the inductor L1 and the capacitor C1 that constitute the LC filter 14F, the voltage V_HV2 in the wiring between the capacitor C1 and the inductor L2, the voltage V_HV3 in the wiring between the inductor L2 and the capacitor C2, A voltage V_HV4 in the wiring between the capacitor C2 and the inductor L3 is obtained by a circuit simulator.

As a result, as shown in FIG. 8B, at time t1 or time t2 when the transistors TU1 to TU4 are switched, the voltage V_HV1 in the wiring between the inductor L1 and the capacitor C1 and the voltage V_HV1 in the wiring between the capacitor C1 and the inductor L2 Although the voltage V_HV2 on the wiring between them, the voltage V_HV3 on the wiring between the inductor L2 and the capacitor C2, and the voltage V_HV4 on the wiring between the capacitor C2 and the inductor L3 fluctuate, they cancel each other out and the fluctuations are greatly suppressed. As a result, compared to the case of FIG. 2(B) (approximately 2,440 volts at the peak value), the voltage is very low, less than half (approximately 1,011 volts at the peak value in the example of FIG. 8(B)). It can be seen that

As described above, according to the second embodiment, similar to the first embodiment, compared with the conventional example, the filter characteristics are the same, that is, the filter characteristics are not degraded. A voltage to ground generated between capacitors can be suppressed.

The above description of the second embodiment relates to the case where the inductor L0 is divided into two, the inductor L0 is divided into three inductors, and the capacitor C0 is divided into two capacitors C1 and C2. However, if the installation area is acceptable, the voltage to ground can be further suppressed by similarly increasing the number of divisions of the inductor and the capacitor.

In the above description, the LC filters 14D, 14E, and 14F are configured with inductors having the same inductance and capacitors having the same capacitance. Alternatively, capacitors with different capacitances can be combined to function as a capacitor with the desired capacitance.

In this case, the voltage across the inductor with the largest inductance or the applied voltage across the capacitor with the smallest capacitance defines the voltage-to-ground generated between the inductor and the capacitor, without degrading the filter characteristics. , the voltage to ground generated between the inductor and the capacitor can be suppressed.

[3] Third Embodiment FIG. 9 is an explanatory diagram of the third embodiment.
In FIG. 9, parts similar to those in FIGS. 1 and 2 of the first embodiment are denoted by the same reference numerals.

In the third embodiment, the number m of inductors constituting the LC filter is m=n when expressed using the number n of capacitors.
Also, the LC filter 14G shown in FIG. 9 will be described as having the same characteristics as the LC filter 14P shown in FIG.

That is, when the inductances of the inductors L1 to Ln are assumed to be the inductances LL1 to LLn, the relationship between the inductor L0 and the inductance LL0 is as follows.
LL0=LL1+LL2+...+LL(n-1)+LLn

When the capacitances of the capacitors C1 to Cn are CC1 to CCn, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2+...+1/CC(n-1)+1/CCn

Next, a first specific example of the third embodiment will be described.
FIG. 10 is an explanatory diagram of a specific example of the third embodiment.
Here, for ease of understanding, the case of m=n=2 will be specifically described as an example.
In FIG. 10, parts similar to those in FIG. 2 are given the same reference numerals.

10 differs from FIG. 2 in that capacitor C1 and capacitor C2 are provided instead of capacitor C0, inductor L1 and inductor L2 are provided instead of inductor L0, and capacitor C1→inductor L1→capacitor C2→inductor L2. It is a point connected in series in order.

In this case, as described above, when the inductances of the inductors L1 and L2 are set to the inductances LL1 and LL2, the relationship between the inductor L0 and the inductance LL0 is expressed by the following equation.
L0 = LL1 + LL2

That is, inductance LL1=LL0/2 and inductance LL2=LL0/2.
For example, LL0/2=LL1=LL2 satisfies the above equation.

In the above example, the inductors L1 and L2 have the same inductance magnitude, and the inductors L1 and L2 are connected in series via the capacitor C2. Let V10 be the voltage applied to inductor L1, V11 be the voltage applied to inductor L1, and V12 be the voltage applied to inductor L2.
V11=V12=V10/2

On the other hand, since the voltage V L applied to the inductor L0 shown in FIG. ₂ is V, the voltage V11 applied to the inductor L1 and the voltage V12 applied to the inductor L2 are lower than in the conventional example. I know it will be.

On the other hand, as described above, when the inductances of the capacitors C1 and C2 are the capacitances CC1 and CC2, the relationship between the capacitance CC0 of the capacitor C0 and the capacitance CC0 is as follows.
1/CC0=1/CC1+1/CC2
For example, 2·CC0=CC1=CC2 satisfies the above equation.

In the above example, the capacitances of the capacitors C1 and C2 are the same, and the capacitors C1 and C2 are connected in series via the inductor L1. Assuming that the voltage applied to C1 is V1 and the voltage applied to capacitor C2 is V2, the following is obtained.
V1=V2=V·CC1/(CC1+CC2)
=V·CC2/(CC1+CC2)

In this case, since the voltage Vc=V applied to the capacitor C0 shown in FIG. 2, the voltage V1 applied to the capacitor C1, the voltage V3 applied to the voltage V2 applied to the capacitor C2, and It can be seen that it is lower than in the case of

When the voltage V_HV1 in the wiring between the capacitor C0 and the inductor L1 constituting the LC filter 14H is obtained by a circuit simulator, as shown in FIG. At time t2, the potential fluctuation is suppressed, and the voltage V_HV1 on the wiring between inductor L0 and capacitor C1 becomes a low voltage ( In the example of FIG. 10B, the peak value is about 1,425 volts).

Similarly, when the voltage V_HV2 in the wiring between the inductor L1 and the capacitor C2 forming the LC filter 14F is obtained by a circuit simulator, as shown in FIG. The voltage V_HV2 on the wiring between, although rising, is a very low voltage (in the example of FIG. 10B, peak It can be seen that the peak value is about 500 volts).

Furthermore, when the voltage V_HV3 in the wiring between the capacitor C2 and the inductor L2 that constitute the LC filter 14F is obtained by a circuit simulator, as shown in FIG. The voltage V_HV3 is a low voltage (approximately 1,200 volts at peak value in the example of FIG. 10B) compared to the case of FIG. 2B (approximately 2,440 volts at peak value). I know there is.

As described above, according to the third embodiment, similar to the first embodiment, compared with the conventional example, the filter characteristics are the same, that is, the filter characteristics are not degraded. A voltage to ground generated between capacitors can be suppressed.

In the above description, the inductor L0 is divided into two and the capacitor C0 is divided into two capacitors C1 and C2. By similarly increasing the number, it is possible to further suppress the voltage to ground.

In the above description, the LC filters 14G and 14H are configured with inductors having the same inductance and capacitors having the same capacitance. It is also possible to combine capacitors with different capacitances to function as a capacitor with a desired capacitance.

In this case, the voltage across the inductor with the largest inductance or the applied voltage across the capacitor with the smallest capacitance defines the voltage-to-ground generated between the inductor and the capacitor, without degrading the filter characteristics. , the voltage to ground generated between the inductor and the capacitor can be suppressed.

It should be noted that the above-described embodiments and modifications can be combined as appropriate, and are merely examples and do not limit the scope of the invention. In addition, the above-described embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Class-D amplifier 11... PWM circuit 12... Gate driver part 13... Full-bridge switching circuit (voltage conversion circuit) 14, 14A-14F... LC filter, 15... Transformer, 16... DC power supply part, LD... Load, L1, L2, L3, . . . , Lm .. inductor (first element), C1, C2, C3, .

Claims (2)

a voltage conversion circuit having a pair of output terminals and converting a DC voltage to an AC voltage;
a filter circuit having an inductor as a first element and a capacitor as a second element connected in series, one end of which is connected to one of the output terminals of the voltage conversion circuit;
a transformer having one end connected to the other end of the filter circuit and the other end connected to the other output terminal of the voltage conversion circuit;
When the number of the first elements is m (m: a natural number of 1 or more) and the number of the second elements is n (n: a natural number of 1 or more), m × n ≥ 2,
Furthermore, when the inductance set in the filter circuit is LL0 and the capacitance is CC0,
inductances of the m first elements are LL1, LL2, LL3, . . . , LLm, respectively;
the capacitances of the n second elements are CC1, CC2, CC3, . . . , CCn, respectively;
LL1+LL2+LL3+...+LLm=LL0
1/CC1+1/CC2+1/CC3+...+1/CCn=1/CC0
and
In the filter circuit, the first elements and the second elements are alternately arranged,
Power supply. In the filter circuit,
when the number of the first elements is two or more, all the first elements have the same inductance;
if the number of said second elements is two or more, said second elements all have the same capacitance;
The power supply device according to claim 1 .

Images