JPH0946144A - Insulated class d amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a class D amplifier whose output is isolated from a voltage source and in which a maximum output is properly set. SOLUTION: The amplifier is mainly made up of a primary circuit having a transformer 21 and switch means 11, 12 of half bridge, full bridge or push-pull configuration and a secondary circuit having the transformer 21 and combination of one or two switch means 23, 24 in pairs driven complementarily. Then a 3rd signal for driving the secondary side obtained by an output of a logic circuit 19 receiving a 1st signal for driving the primary side and a 2nd signal subject to 2-state modulation of an amplified signal is used to drive the secondary circuit. Thus, the 2-state modulation signal is amplified for the power and the resulting signal is given to a low-pass filter 10 to realize desired isolation and power amplification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of bidirectional power transfer between a voltage source and a load such as amplification of an acoustic signal, motor drive, uninterruptible power supply, etc., and output is AC. The present invention relates to a class D amplifier for high-efficiency power amplification, and more particularly, to a characteristic that a voltage source and a load can be electrically insulated.

[0002]

2. Description of the Related Art In recent years, class D amplifiers have been used for the purpose of highly efficient power amplification of acoustic signals, and have the advantage that particularly high level power can be processed with high efficiency. As a conventional class D amplifier for the purpose of high efficiency power amplification, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 5-152867 filed by the present applicant.

Power amplification in a conventional class D amplifier including the above-mentioned prior art will be described below with reference to the drawings. FIG. 14 is a circuit diagram showing a basic configuration of a power amplification unit in a conventional class D amplifier, and FIG. 15 is an operation explanatory diagram showing an operation of the circuit shown in FIG.

The first and second series-connected first and second voltage sources 1 and 2 having the same power supply voltage V _CC are connected in series.
First and second switch means 3 and 4 are connected in series between both ends of the second voltage sources 1 and 2. A low-pass composed of an inductor 7 and a capacitor 8 with the potential difference v _SS between the connection point of the first and second switch means 3 and 4 and the connection point of the first and second voltage sources 1 and 2 as an input. Load 9 through filter 10
Are connected. The switch means 3 and 4 are complementarily driven by a drive circuit 5 and an inverting drive circuit 6 which _{receive the} two-state modulation signal v _2M .

In the case of a separately excited pulse width modulation class D amplifier, which is one type of two-state modulation, the two-state modulation signal v _2M shown in (B) of FIG. 14) described above and not shown in FIG. 14 can be obtained by comparing the amplified signal v _S with the triangular wave v _T by a comparator. In the following description, it is assumed that all switch means are turned on when the voltage of the control electrode is positive or the logic is H, and turned off when the control electrode voltage is negative or the logic is L. At the connection point of the switch means 3 and 4, the two-state modulation signal v
Ideally the amplitude (0-peak value) of power amplification of _2M is V
_The signal v _SS that is _CC can be obtained. This signal v _SS is input to the low-pass filter 10 and the carrier wave is removed, so that the output v _O obtained by power-amplifying the signal v _S amplified as the output of the low-pass filter 10 as shown in FIG. Can be obtained and this is supplied to the load 9. If necessary, negative feedback (not shown) is carried out to reduce distortion.

Thus, ideally, the power conversion efficiency of 100
%, In reality, loss will occur in the switching means, etc.,
Even so, it is not difficult to secure an efficiency of 80% or more, and extremely efficient amplification is possible compared to general class B amplification, etc., and no heat dissipation structure is required, or it becomes extremely small, and it is small. It is possible to obtain a lightweight amplifier.

Further, FIG. 16 shows a basic structure of a power amplification section in another conventional class D amplifier. This is generally called a BTL configuration and has the characteristic that one power supply is enough.
There are two pairs of serially connected switch means that are driven in a complementary manner, and the two pairs operate in a complementary manner, so that FIG.
As in the conventional example shown in FIG. 4, efficient amplification is possible.

[0008]

However, in order to use such a class D amplifier in a device that uses a commercial AC power supply, a voltage source that is insulated and stepped down from the commercial AC power supply is generally required.

For the purpose of stepping down, in the case of an acoustic amplifier, the load is generally a fixed impedance, and for safety (prevention of heating), the power supply voltage is limited in order to prevent the output from exceeding the maximum output. This is because it is necessary. For example,
In the case of the class D amplifier shown in FIG. 14, the power supply voltage (voltage source 1,
It is necessary to set ± V _CC ) to the value shown in the following (Equation 1) with reference to the connection point of 2.

[0010]

[Equation 1]

However, conversion efficiency 100% PWM wave maximum duty ratio; 100% Pp; maximum output Zo; load impedance Further, in the case of an audio amplifier, the purpose is to insulate from a commercial AC power source, a speaker that becomes a load. This is because there is a high possibility that a person's hand will touch the terminal connecting the terminal and it is necessary to prevent electric shock. If a transformer for insulation is inserted in the output terminal, a transformer that can input a large amount of low frequency power and has little distortion, that is, a large and heavy transformer is required. , Against the purpose.

Generally, as a power supply device for audio, a commercial AC power supply is used as it is as an input of a transformer, and
A transformer-type power supply is used which obtains a DC voltage by rectifying and smoothing the voltage after stepping it down according to the winding ratio between the secondary and secondary windings. This is because the transformer type power supply is inexpensive and the power supply voltage does not require precise stability. However, when a transformer type power supply is used as a power supply device for a class D amplifier, the main component amplifier is highly efficient and therefore small and lightweight, while the subordinate power supply device is very heavy and large. It is an unbalanced thing that there is no freedom of shape. Further, although it is possible to use a switching power supply as the power supply device, there is a problem that the power supply device for acoustics is more expensive than the transformer type power supply.

The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a class D amplifier which has an insulating function with a simple structure and can set an arbitrary maximum output.

[0014]

According to the first characteristic constitution of the insulation type class D amplifier of the present invention for achieving the above object, the first and second voltage sources connected in series and the above series. First and second switch means connected in series between both ends of the connected first and second voltage sources, a connection point of the first and second switch means, and the first and second voltages. A transformer having a primary winding connected to the connection point of the source, and third and fourth series connected to both ends of the first and second secondary windings connected in series of the transformer. Switch means, and the third,
A low-pass filter that receives a potential difference between a connection point of the fourth switch means and a connection point of the first and second secondary windings of the transformer and supplies an output to a load, and a first signal. A first drive circuit for amplifying the first signal to drive the first switch means, and a second drive circuit for inverting and amplifying the first signal to drive the second switch means. A second signal obtained by subjecting the amplified signal to two-state modulation, and a logic circuit for performing logical operation processing on the second signal and the first signal or a signal related to the first signal, A third drive circuit for amplifying a third signal output from the logic circuit to drive the third switch means, and a third drive circuit for inverting and amplifying the third signal to drive the fourth switch means. 4 driving circuit is included.

According to the second characteristic configuration, the voltage source, the first and second switch means connected in series between both ends of the voltage source, and further connected in series between both ends of the voltage source. A transformer having a primary winding connected between third and fourth switch means, a connection point between the first and second switch means, and a connection point between the third and fourth switch means. And fifth and sixth switch means connected in series between both ends of the first and second secondary windings connected in series of the transformer, and a connection point of the fifth and sixth switch means. A low-pass filter that receives a potential difference between the connection points of the first and second secondary windings of the transformer and supplies an output to a load, a first signal, and an amplifier of the first signal. And a first drive circuit for driving the first switch means, and the first signal is inverted and amplified to Second for driving the second switching means
Drive circuit and the third signal by inverting and amplifying the first signal.
A third drive circuit for driving the switch means of the
Drive circuit for amplifying the signal of No. 2 and driving the above-mentioned fourth switch unit, and the second drive circuit for modulating the amplified signal in two states
And a logic circuit that performs logical operation processing of the second signal and the first signal or a signal related to the first signal, and a third signal that is the output of the logic circuit is amplified. A fifth drive circuit for driving the fifth switch means and a sixth drive circuit for inverting and amplifying the third signal to drive the sixth switch means.

According to the third characteristic configuration, the transformer having the first and second primary windings connected in series and the transformer having the first and second primary windings connected in series of the transformer are provided. First and second switch means connected in series between both ends, and connected between the first and second switch means and the connection point of the first and second primary windings of the transformer. Voltage source, third and fourth switching means connected in series between both ends of the first and second secondary windings connected in series of the transformer, and the third and fourth switching means. A low-pass filter that receives a potential difference between a connection point and the connection points of the first and second secondary windings of the transformer and supplies an output to a load, a first signal, and the first signal A first drive circuit for driving the first switch means and amplifying the first signal; Second driving the second switching means
Drive circuit, a second signal obtained by performing two-state modulation on a signal to be amplified, and a logic circuit for performing logical operation processing on the second signal and the first signal or a signal related to the first signal. And a third drive circuit for amplifying a third signal output from the logic circuit to drive the third switch means,
And a fourth drive circuit for inverting and amplifying the third signal to drive the fourth switch means.

According to the fourth characteristic configuration, the first and second voltage sources connected in series, and the first and second voltage sources connected in series.
First and second switch means connected in series between both ends of the voltage source, and a connection point of the first and second switch means,
1 connected between the connection point of the first and second voltage sources
A transformer having a secondary winding, third and fourth switch means connected in series between both ends of the secondary winding of the transformer, and further connected in series between both ends of the secondary winding of the transformer. The potential difference between the connection point of the fifth and sixth switch means, the third and fourth switch means, and the connection point of the fifth and sixth switch means is input and the output is supplied to the load. A low-pass filter, a first signal, a first drive circuit for amplifying the first signal to drive the first switch means, and a second switch for inverting and amplifying the first signal. Logic of a second drive circuit for driving the means, a second signal obtained by two-state modulating the amplified signal, the second signal and the first signal or a signal related to the first signal. Increase the logic circuit that performs arithmetic processing and the third signal that is the output of the logic circuit. A fourth driver circuit for driving the third drive circuit and said third a signal by inverting amplifying said fourth switching means for driving the third switching means and,
A fifth drive circuit for inverting and amplifying the third signal to drive the fifth switch means, and a sixth drive circuit for amplifying the third signal and drive the sixth switch means. It is characterized by including.

According to the fifth characteristic configuration, a voltage source, first and second switch means connected in series between both ends of the voltage source, and further connected in series between both ends of the voltage source. A transformer having a primary winding connected between third and fourth switch means, a connection point between the first and second switch means, and a connection point between the third and fourth switch means. And a fifth connected in series between both ends of the secondary winding of the transformer,
Sixth switch means, further seventh and eighth switch means connected in series between both ends of the secondary winding of the transformer, connection points of the fifth and sixth switch means, and the seventh switch means. , A low-pass filter that receives a potential difference between the eighth switch means and an output and supplies an output to a load, a first signal, and amplifies the first signal to drive the first switch means. 1 drive circuit, a second drive circuit for inverting and amplifying the first signal to drive the second switch means, and a second drive circuit for inverting and amplifying the first signal to drive the third switch means A third drive circuit, a fourth drive circuit for amplifying the first signal to drive the fourth switch means, a second signal obtained by modulating the amplified signal in two states, and The second signal and the first signal or a signal related to the first signal A logic circuit for performing logical operation processing, a fifth drive circuit for amplifying a third signal output from the logic circuit to drive the fifth switch means, and an inversion amplification for the third signal. A sixth drive circuit for driving the sixth switch means, a seventh drive circuit for inverting and amplifying the third signal to drive the seventh switch means, and an amplifier for the third signal. And an eighth drive circuit for driving the eighth switch means.

According to a sixth characteristic configuration, a transformer having first and second primary windings connected in series and a transformer having the first and second primary windings connected in series of the transformer are provided. First and second switch means connected in series between both ends, and connected between the first and second switch means and the connection point of the first and second primary windings of the transformer. A third voltage source connected in series between both ends of the secondary winding of the transformer,
A fourth switch means, and further the above-mentioned transformer 2
Input the potential difference between the fifth and sixth switch means connected in series between both ends of the next winding, the connection point of the third and fourth switch means, and the fifth and sixth switch means. age,
A low-pass filter that supplies an output to a load, a first signal, a first drive circuit that amplifies the first signal to drive the first switch means, and amplifies and inverts the first signal. A second drive circuit for driving the second switch means, and a second signal obtained by subjecting the amplified signal to two-state modulation,
A logic circuit that performs logical operation processing of the second signal and the first signal or a signal related to the first signal, and a third signal that is an output of the logic circuit is amplified to amplify the third signal.
And a third drive circuit for driving the switch means of
A fourth drive circuit that inverts and amplifies the signal of 4 to drive the fourth switch means, a fifth drive circuit that inverts and amplifies the third signal to drive the fifth switch means, and And a sixth drive circuit for amplifying the third signal to drive the sixth switch means.

[0020]

According to the present invention, with the above construction, a power-amplified two-state modulation signal having an amplitude determined by the power supply voltage and the primary / secondary turns ratio of the transformer is obtained at the input of the low-pass filter. This can be passed through a low-pass filter to ensure electrical isolation between the voltage source and the load by the transformer, and the maximum output to the specified value by the above amplitude, and the desired amplification for the load. An AC signal can be supplied.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. It is to be noted that the reference numerals assigned in FIG. 1 to those performing the same operation as in FIG. 14 are basically assigned the same reference numerals.

Both are connected in series and the power supply voltage is V_CCIs
The first and second voltage sources 1 and 2 and the first and second voltage sources connected in series
The first and second voltage sources 1, 2 connected in series between both ends of the first
First and second switch means 11, 12 and the first and second switch means
Connection point of the switch means 11 and 12 of the above, and the first and second
Number of turns n connected between the connection points of the voltage sources 1 and 2 of₁Of 1
Of the transformer 21 having the secondary winding 22 and the transformer 21
N connected in series with n turns₂The first and second secondary volumes
Third and fourth switches connected in series between both ends of the lines 23 and 24.
Switch means 13, 14 and the third and fourth switch hands
The connection point of the stages 13 and 14 and the first of the transformer 21,
Potential difference v between the connection point of the second secondary windings 23 and 24_SS
Input and output v_OTo load 9 and inductor 7
And a low-pass filter 10 composed of a capacitor 8,
The first signal v that is a rectangular wave with a duty ratio of 50%
_PCAnd the first signal v_PCTo amplify the first switch
First driving circuit 15 for driving the driving means 11 and the first driving circuit 15
The signal v_PCThe second switching means 12 by inverting and amplifying
A second drive circuit 16 for driving the
Second signal v obtained by two-state modulation of the signal_2MAnd the second
Signal v_2MAnd the first signal v _PCExclusive NOR logic with
The logic circuit 19 that performs arithmetic processing and the output of the logic circuit 19
Third signal v, which is force_SCTo amplify the third switch
A third drive circuit 17 for driving the means 13 and the third drive circuit
Signal v_SCIs inverted and amplified, and the fourth switch means 14 is
And a fourth drive circuit 18 for driving.

FIG. 2 is an operation explanatory diagram showing the operation of each part when the circuit of FIG. 1 is controlled by using the separately excited pulse width modulator which is one type of two-state modulation.

2A shows a triangular wave v _T and a signal v _S to be amplified which are not shown in FIG. By comparing these two kinds of signals with a comparator not shown in FIG. 1, the two-state modulation signal v _2M shown in FIG. 2B can be obtained.

The duty ratio is 50% in (C) of FIG.
Shows a first signal v _PC which is a square wave of. By using the first signal v _PC to complementarily drive the first and second switch means 11 and 12 via the first and second drive circuits 15 and 16, the voltage sources 1 and 2 can be obtained. The voltage v _{P1 at} the connection point of the switch means 11 and 12 with reference to the connection point of
As a voltage across the primary winding 22 of the transformer 21,
Can be obtained by power-amplifying the signal v _PC , whose waveform is proportional to the first signal v _PC , and whose amplitude (0-peak value) is ideally V _CC .

As a result, the other ends of the first and second secondary windings 23 and 24 based on the connection point of the first and second secondary windings 23 and 24 connected in series in the transformer 21. Output voltage v
_{For S1} and v _S2 , the waveform is proportional to the first signal v _PC , and its amplitude V _S-0P (0-peak value) is ideally as follows.

V _S-0P = V _CC × n ₂ / n ₁ That is, the amplitude proportional to the power supply voltage and the winding ratio between the primary and secondary windings can be obtained.

By inputting the first signal v _PC and the two-state modulation signal v _2M to the logic circuit 19 which performs the exclusive NOR logical operation processing, the third signal v _SC shown in (D) of FIG.
Can be obtained.

The third and fourth switch means 1 is supplied via the third and fourth drive circuits 17 and 18 using the third signal v _SC.
By complementarily driving 3, 14
The signal v _SS shown in (E) of FIG. 2 can be obtained at the connection point of the switch means 13 and 14 of FIG. A truth table of logical operations for obtaining this signal v _SS is shown in (Table 1).

[0031]

[Table 1]

However, on the primary side of the transformer, the connection point of the first and second voltage sources 1 and 2 is used as a reference voltage point, and on the secondary side of the transformer, the first and second secondary windings 23 of the transformer 21, 24
The connection point of is the reference voltage point. However, when the voltage is positive, the logic is H, and when the voltage is negative, it is the logic L.

As can be confirmed from the truth table shown in (Table 1), the signal v _SS shown in (E) of FIG. 2 is the two-state modulation signal v _2M shown in (B) of FIG. The power is amplified, and the amplitude is ideally V _CC × n ₂ like V _S-0P.
/ N ₁ .

By passing this signal v _SS through a low-pass filter 10, an output v _O obtained by power-amplifying the amplified signal v _S shown in (A) of FIG. 2 as shown in (F) of FIG. Can be obtained.

The first and second secondary of the transformer 21
Amplitude V of the output voltage of the windings 23 and 24 _S-0P(As described above
Ideally V_CC× n₂/ N₁₎Is the power supply voltage V of the conventional example_CCPhase
This limits the maximum output power,
Power supply voltage V of the embodiment_CCIn accordance with the number of primary and secondary turns n₁,
n₂The maximum output can be set by setting
In both cases, the transformer 21 causes
This ensures the electrical insulation between the voltage source and the load.
ing.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. It should be noted that the reference numerals given in FIG.
The same reference numerals are basically given to those assigned to those performing the same operation as those in FIG.

The first and second voltage sources 1 and 2 which are connected in series and have a power supply voltage of V _CC , and the first and second voltage sources 1 and 2 which are connected in series are connected in series. The first and second switch means 11 and 12 and the first and second switch means
Connection point of the switch means 11 and 12 of the above, and the first and second
1 of the number of turns n ₁ connected between the connection point of the voltage sources 1 and 2 of
A transformer 21 having a secondary winding 22 and third and third transformers 21 connected in series between both ends of the first and second secondary windings 23 and 24 in which the number of turns of the transformer 21 connected in series are both n ₂ Between the four switch means 13, 14 and the connection point of the third and fourth switch means 13, 14 and the connection point of the first and second secondary windings 23, 24 of the transformer 21. A low-pass filter 10 that receives the potential difference v _SS as an input and is configured by an inductor 7 and a capacitor 8 to supply an output to a load 9; a first signal v _PC that is a rectangular wave with a duty ratio of 50%;
A first drive circuit 15 for amplifying the first signal v _PC to drive the first switch means 11, and an inversion amplification of the first signal v _PC for driving the second switch means 12. Second drive circuit 16, a second signal v _2M obtained by two-state modulating an amplified signal (not shown), and the second signal v
_A logic circuit 19 for performing a logical operation process of exclusive NOR logic between _2M and the output signal v _S3 of the control winding 25 on the secondary side of the transformer 21, and a third signal v _SC which is the output of the logic circuit 19. A third drive circuit 17 that amplifies the third switch means 13 to drive the third switch means 13, and a fourth drive circuit 18 that inverts and amplifies the third signal v _SC to drive the fourth switch means 14. Including and Basically, it is the same as the circuit of the first embodiment shown in FIG. 1, but in the case of the first embodiment shown in FIG. 1, the signal that becomes the input of the logic circuit 19 together with the two-state signal v _2M Is the first signal v _PC , but in the case of the second embodiment shown in FIG. 3, the control winding 2 on the secondary side of the transformer 21 is
5 is the output signal v _S3 .

Output of the control winding 25 on the secondary side of the transformer 21
Force signal v_S3Output voltage of the primary winding 22 of the transformer 21
Voltage v_P1Is in proportion to the winding number ratio and the first embodiment
As is clear from the explanation of the above, the primary winding voltage of the transformer 21 is
Pressure v_P1Is the first signal v_PCIs power amplified?
Output signal v of the control winding 25 on the secondary side of the transformer 21
_S3Is the first signal v_PCThe waveform is proportional to. That is, 2
Output signal v of the control winding 25 on the secondary side_S3And the first signal v_PCIs
Because of the proportional relationship, the output of the logic circuit 19 is shown in FIG.
The first embodiment and the second embodiment shown in FIG. 3 are completely the same.
This is one operation, and the second embodiment shown in FIG.
As with the first embodiment shown, there is an electrical connection between the voltage source and the load.
To ensure the desired insulation and set the desired maximum output.
It is possible to provide a class D amplifier capable of performing the above.

Here, the signal that is input to the logic circuit 19 together with the two-state signal v _2M is the output signal of the control winding 25 on the secondary side of the transformer 21, but this signal is a signal that only takes timing. However, since its size is determined only by the allowable input range of the input logic circuit, the control winding on the secondary side of the transformer is connected to the winding on the other secondary side of the transformer, or , There is no problem even if the intermediate tap is provided on a part of the other secondary winding of the transformer or the other secondary winding of the transformer is wound. It has the effect of reducing the number of windings.

The first embodiment shown in FIG. 1 and FIG.
In both cases, the impedance seen from the primary winding of the transformer 21 in the direction of the voltage source is always connected to the voltage source 1 or 2 by the switch means 11 or 12. Since the impedance of the transformer 21 is very low, the impedance seen from the secondary winding of the transformer 21 in the load direction is always connected to the load via the switch means 13 or 14 and the inductor 7. Has high impedance. Therefore, the excitation state of the transformer is determined by the duty ratio of the primary side switching means and the voltage values of the voltage sources 1 and 2. Although the voltage values of the voltage sources 1 and 2 are equal and the duty ratio of the first signal v _PC is 50% in the above embodiment, for example, when the voltage values of the voltage sources 1 and 2 are different, the transformer The duty ratio of the first signal v _PC is set to 50% to prevent magnetic bias.
It needs to be moved away. The specific method of this is no different from that of a general half-bridge type switching power supply.

The following can be said when the idea of the excited state of the transformer is expanded. The basic configuration of the primary side circuit of the circuits of FIGS. 1 and 3 used in the description of the first and second embodiments is a half bridge configuration as shown in FIG. With this half-bridge structure, the magnetic flux density of the transformer core reciprocates positively and negatively. This is the same as the concept of the excitation of the transformer described above, and is determined by the driving method on the primary side of the transformer. As the circuit configuration of the primary side circuit in which the movement of the magnetic flux density of the transformer operates similarly to the half-bridge configuration, the full-bridge configuration shown in FIG. 5 or
There is a push-pull configuration shown in FIG. 6, and both can obtain a signal obtained by amplifying the two-state modulated signal v _2M at the input part of the secondary side low-pass filter, as in the first and second embodiments. It is possible to provide a class D amplifier which is the object of the present invention and which can ensure electrical insulation between a voltage source and a load and can set a desired maximum output.

Further, the basic structure of the secondary side circuit of the circuits of FIGS. 1 and 3 used in the description of the first and second embodiments is as shown in FIG. 7, and the non-insulated type D shown in FIG. 14 is used. Although the voltage source of the basic circuit of the class amplifier is replaced by the secondary winding of the transformer, as another conventional example, the power supply section of the non-isolated class D amplifier having the output of the BTL configuration shown in FIG. It is obvious that the circuit configuration shown in FIG. 8 in which the next winding is replaced operates similarly.

That is, the basic configuration on the primary side can be three as shown in FIGS. 4, 5 and 6, and the basic configuration on the secondary side can be two as shown in FIGS. 7 and 8. Primary, 2
As a basic configuration combining the following, 6 configurations of 3 × 2 are possible, and the generation method of v _PC shown in FIGS. 4, 5 and 6 and v _SC shown in FIGS. The control methods are all the same, and the control method of both the first and second embodiments shown in FIGS. 1 and 3 can be used.

Of the six configurations described above, the first implementation is carried out for five combinations except the combinations shown in the first and second embodiments shown in FIGS. 1 and 3 corresponding to claim 1. A more specific circuit configuration using the control method shown in the example is shown in FIG. 9 which is a circuit diagram showing a third embodiment corresponding to claim 2, and a fourth embodiment corresponding to claim 3. 10 is a circuit diagram, FIG. 11 is a circuit diagram showing a sixth embodiment corresponding to claim 4, FIG. 12 is a circuit diagram showing a sixth embodiment corresponding to claim 5, and FIG. 13 is a circuit diagram showing a seventh embodiment corresponding to FIG. In the circuits showing the third to seventh embodiments shown in FIGS. 9 to 13,
As described above, the control method described in the second embodiment shown in FIG. 3 can be used as the control method.

In addition, the circuit configuration may be simplified by inverting amplification with a class D amplifier for negative feedback or the like. However, in such a case, it is excluded as a logic circuit in any of the embodiments. Inversion amplification is possible by using a dynamic OR circuit. Further, in the case of the control method described in the second embodiment shown in FIG. 3, inverting amplification can also be performed by reversing the polarity of the control winding on the secondary side.

Further, in the above description, the voltage source is described as a direct current, but a voltage obtained by rectifying and smoothing a commercial alternating current power source does not pose any problem. In this case, it suffices to replace the voltage source used in the description with reference to FIGS. 1 and 2 with the capacitor of the smoothing unit. In addition, in the first and second embodiments shown in FIGS. 1 and 3 described above, the separately excited PWM modulation method is used to obtain the two-state modulation signal for explanation of the operation. It is clear that how the signal is produced has no effect on the operation of the class D amplifier of the present invention, including that a two-state modulated signal can only be used on the secondary side of the transformer. In addition to the two-state modulation method, such as the modulation method disclosed in Japanese Patent Laid-Open No. 5-152867, which has been clarified as a prior art example, most of known two-state modulation techniques such as general self-excited PWM and PDM are used. It can be used.

[0047]

As described above, according to the present invention, the maximum output can be arbitrarily set with a simple structure, the insulation between the voltage source and the load can be obtained, and an independent power supply device is not required. It is possible to provide a small and lightweight class D amplifier that receives a commercial AC power supply as an input.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment shown in FIG.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a first basic form of a primary circuit of the present invention.

FIG. 5 is a circuit diagram showing a second basic form of the primary circuit of the present invention.

FIG. 6 is a circuit diagram showing a third basic form of the primary circuit of the present invention.

FIG. 7 is a circuit diagram showing a first basic form of a secondary circuit of the present invention.

FIG. 8 is a circuit diagram showing a second basic form of a secondary circuit of the present invention.

FIG. 9 is a circuit diagram showing a third embodiment of the present invention.

FIG. 10 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 11 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 12 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 13 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 14 is a circuit diagram showing a basic configuration of a power amplification unit in a conventional example.

FIG. 15 is an operation explanatory view of the conventional example shown in FIG.

FIG. 16 is a circuit diagram showing a basic configuration of a power amplification unit in another conventional example.

[Explanation of symbols]

1, 2 Voltage source 3, 4, 11, 12, 13, 14 Switch means 5, 15, 17 Amplification drive circuit 6, 16, 18 Inversion amplification drive circuit 7 Inductor 8 Capacitor 9 Load 10 Low-pass filter 19 Logic circuit 21 Transformer 22 Primary winding 23 of the transformer 21 First secondary winding of the transformer 21 Second secondary winding of the transformer 21 Control winding on the secondary side of the transformer 21 v _PC First signal v _P1 Transformer 21 Voltage of the primary winding 22 of v _S1 voltage of the first secondary winding 23 of the _S21 transformer v voltage of the second secondary winding 24 of the _S2 transformer 21 v control winding of the secondary side of the _S21 transformer 25 output signal v _2M Amplified signal v _S two-state modulated signal v _SC Logic circuit 19 output signal v _SS Low-pass filter 10 input voltage

Claims (13)

[Claims] 1. A first and second voltage source connected in series, and first and second switch means connected in series between both ends of the first and second voltage source connected in series. A transformer having a primary winding connected between a connection point of the first and second switch means and a connection point of the first and second voltage sources, and a first series connection of the transformer. , Third and fourth switch means connected in series between both ends of the second secondary winding, connection points of the third and fourth switch means, and the first and second two of the transformer. A low-pass filter which receives a potential difference between the connection point of the next winding and an output and supplies an output to a load; a first signal; and a first signal for amplifying the first signal to drive the first switch means. And a second drive circuit for inverting and amplifying the first signal to drive the second switch means. A second signal obtained by subjecting the amplified signal to two-state modulation, and a logic circuit for performing a logical operation process on the second signal and the first signal or a signal related to the first signal; A third drive circuit that amplifies a third signal output from the circuit to drive the third switch means, and a fourth drive circuit that inverts and amplifies the third signal to drive the fourth switch means. And a drive circuit for the isolated class D amplifier. 2. A voltage source, first and second switch means connected in series between both ends of the voltage source, and third and fourth switches connected in series between both ends of the voltage source. Means, a connection point of the first and second switch means, and the third,
A transformer having a primary winding connected to the connection point of the fourth switch means; and a transformer connected in series between both ends of the first and second secondary windings connected in series of the transformer. The fifth and sixth switch means, the potential difference between the connection points of the fifth and sixth switch means and the connection points of the first and second secondary windings of the transformer are input, and the output is A low-pass filter for supplying to a load, a first signal, a first drive circuit for amplifying the first signal to drive the first switch means, and an inversion amplification of the first signal for amplifying the first signal. A second drive circuit for driving the second switch means; a third drive circuit for inverting and amplifying the first signal to drive the third switch means; and a third drive circuit for amplifying the first signal A fourth drive circuit for driving the fourth switch means, and a signal to be amplified in two states A second adjusted signal, a logic circuit for performing a logical operation processing of the second signal and the first signal or a signal related to the first signal, and a third circuit which is an output of the logic circuit. A fifth drive circuit for amplifying a signal to drive the fifth switch means; and a sixth drive circuit for inverting and amplifying the third signal to drive the sixth switch means. Characteristic isolated class D amplifier. 3. A transformer having first and second primary windings connected in series, and a transformer connected in series between both ends of the first and second primary windings connected in series of the transformer. First and second switch means, a voltage source connected between the first and second switch means and a connection point of the first and second primary windings of the transformer, and the transformer The third and fourth switch means connected in series between both ends of the first and second secondary windings connected in series, the connection point of the third and fourth switch means, and the transformer described above. A low-pass filter that receives a potential difference between the connection point of the first and second secondary windings and that supplies an output to a load, a first signal, and the first signal by amplifying the first signal. A first drive circuit for driving the switch means of the above, and the second switch means by inverting and amplifying the first signal. Second driving circuit for driving, second signal obtained by performing two-state modulation on the amplified signal, and logical operation processing of the second signal and the first signal or a signal related to the first signal A third drive circuit for driving the third switch means by amplifying a third signal output from the logic circuit, and a fourth drive circuit for inverting and amplifying the third signal. And a fourth drive circuit for driving the switch means of 1. 4. A first and second voltage source connected in series, and first and second switch means connected in series between both ends of the first and second voltage source connected in series. The connection point of the first and second switch means, and the first and
A transformer having a primary winding connected to a connection point of a second voltage source, and third and fourth switching means connected in series between both ends of the secondary winding of the transformer, , Fifth and sixth switch means connected in series between both ends of the secondary winding of the transformer, connection points of the third and fourth switch means, and connection of the fifth and sixth switch means Input the potential difference between the point and
A low-pass filter that supplies an output to a load, a first signal, a first drive circuit that amplifies the first signal to drive the first switch means, and an inversion amplification of the first signal. A second drive circuit for driving the second switch means, a second signal obtained by modulating the amplified signal in two states, the second signal and the first signal or the first signal. A logic circuit that performs a logical operation process with a related signal; a third drive circuit that amplifies a third signal output from the logic circuit to drive the third switch means; and the third signal A fourth drive circuit for inverting and amplifying the signal to drive the fourth switch means, a fifth drive circuit for inverting and amplifying the third signal to drive the fifth switch means, and the third A signal for amplifying the signal of to drive the sixth switch means. Isolated class D amplifier characterized in that it comprises a dynamic circuit. 5. A voltage source, first and second switch means connected in series between both ends of the voltage source, and third and fourth switches connected in series between both ends of the voltage source. Means, a connection point of the first and second switch means, and the third,
A transformer having a primary winding connected to the connection point of the fourth switch means, and fifth and sixth switch means connected in series between both ends of the secondary winding of the transformer, The seventh and eighth switch means connected in series between both ends of the secondary winding of the transformer, the connection point of the fifth and sixth switch means, and the seventh and eighth switch means. A low-pass filter that receives a potential difference between them as an input and supplies an output to a load; a first signal; a first drive circuit that amplifies the first signal to drive the first switch means; A second drive circuit for inverting and amplifying the first signal to drive the second switch means; and a third drive circuit for inverting and amplifying the first signal to drive the third switch means, A first amplifier for amplifying the first signal to drive the fourth switch means Drive circuit, a second signal obtained by performing two-state modulation on a signal to be amplified, and a logic circuit for performing logical operation processing on the second signal and the first signal or a signal related to the first signal. A fifth drive circuit that amplifies a third signal output from the logic circuit to drive the fifth switch means; and a fifth drive circuit that inverts and amplifies the third signal to drive the sixth switch means. A sixth drive circuit for driving; a seventh drive circuit for inverting and amplifying the third signal to drive the seventh switch means; and a seventh drive circuit for amplifying the third signal and the eighth switch means. And an eighth drive circuit for driving the isolated class D amplifier. 6. A transformer having first and second primary windings connected in series, and a transformer connected in series between both ends of the first and second primary windings connected in series of the transformer. First and second switch means, a voltage source connected between the first and second switch means and a connection point of the first and second primary windings of the transformer, and the transformer Third and fourth switch means connected in series between both ends of the secondary winding of the transformer, and fifth and sixth switch means connected in series between both ends of the secondary winding of the transformer. A low-pass filter that receives the potential difference between the connection point of the third and fourth switch means and the fifth and sixth switch means as an input and supplies an output to a load; a first signal; A first drive circuit for amplifying a signal of No. 1 to drive the first switch means; A second drive circuit for inverting and amplifying a signal to drive the second switch means; a second signal obtained by modulating the amplified signal in two states; the second signal and the first signal or the above A logic circuit that performs logical operation processing with a signal related to the first signal; a third drive circuit that amplifies a third signal that is an output of the logic circuit and drives the third switch means; A fourth drive circuit for inverting and amplifying the third signal to drive the fourth switch means, and a fifth drive circuit for inverting and amplifying the third signal and driving the fifth switch means. And a sixth drive circuit for amplifying the third signal and driving the sixth switch means, the isolated class D amplifier. 7. The insulation according to claim 1, wherein the signal related to the first signal is an output signal of a control winding wound on the secondary side of the transformer. Type class D amplifier. 8. The control winding on the secondary side of the transformer,
Another secondary winding of the transformer, or one of the other secondary windings of the transformer with an intermediate tap, or another secondary winding of the transformer The insulated class D amplifier according to claim 7, wherein the wound type is also used. 9. The voltage values of the first and second voltage sources are substantially equal to each other, and the first signal has a duty ratio of about 50%.
4. The rectangular wave of claim 1 or 4,
An isolated class D amplifier according to item 1. 10. The duty ratio of the first signal is approximately 50.
% Rectangular wave.
Alternatively, the isolated class D amplifier according to item 6. 11. The isolated class D amplifier according to claim 1, wherein a logic circuit for obtaining an exclusive NOR logic is used as the logic circuit. 12. A logic circuit for obtaining an exclusive OR logic is used as the logic circuit.
0. The isolated class D amplifier according to 0. 13. Each of the low-pass filters is 1
13. The isolated class D amplifier according to claim 1, wherein a combination of one or more inductors and capacitors is used.