KR102569138B1 - LLC resonant converter for D-Class AMP by use of voltage-gain variation control - Google Patents

Abstract

The present invention generally relates to an LLC resonant converter for a D-Class amplifier. In particular, the present invention monitors the operating state of the D-Class amplifier, sets the voltage gain of the converter low while the D-Class amplifier is operating, and relatively raises the voltage gain of the converter when the D-Class amplifier enters the normal state. By setting, the D-Class based on variable voltage gain control can solve all the problems of the prior art, such as instability during startup of the D-Class amplifier due to the rise in no-load voltage and decrease in the maximum output performance of the D-Class amplifier due to the drop in the maximum load voltage. It relates to an LLC resonant converter for an amplifier. According to the present invention, it is possible to use a small-capacity transformer element in the LLC resonant converter for the D-Class amplifier, thereby reducing manufacturing cost and achieving high efficiency, light weight, and miniaturization of the product.

Description

LLC resonant converter for D-Class AMP based on voltage gain variable control {LLC resonant converter for D-Class AMP by use of voltage-gain variation control}

The present invention generally relates to an LLC resonant converter for a D-Class amplifier.

In particular, the present invention monitors the operating state of the D-Class amplifier, sets the voltage gain of the converter low while the D-Class amplifier is operating, and relatively raises the voltage gain of the converter when the D-Class amplifier enters the normal state. By setting, the D-Class based on variable voltage gain control can solve all the problems of the prior art, such as instability during startup of the D-Class amplifier due to the rise in no-load voltage and decrease in the maximum output performance of the D-Class amplifier due to the drop in the maximum load voltage. It relates to an LLC resonant converter for an amplifier.

Currently, it is common to use an LLC resonant converter as a power source for D-Class amplifiers. It is possible to design the power supply of the D-Class amplifier with various topologies, but if a topology other than the LLC resonant converter is applied to the D-Class amplifier of 300W or more, the loss increases and it is inefficient.

1 is a diagram showing a general circuit configuration of an LLC resonant converter.

In general, an LLC resonant converter uses a resonance phenomenon between a capacitor and an inductor. That is, the LLC resonant converter includes a resonant capacitor and a resonant inductor for generating a resonant phenomenon. In addition, the LLC resonant converter includes switches for driving, and the input current may be discontinuous according to the on/off operation of the switches. When the input current becomes discontinuous, noise is generated. To prevent this, an LC filter is used. In the LLC resonant converter, the output voltage ratio is mainly determined by a turn-ratio between windings included in a transformer component.

Referring to FIG. 1, the LLC resonant converter includes a switch unit 11 for outputting a rectangular wave power source Vs by an alternating switching operation of a switching element when a DC input power source Vg is applied, and a rectangular wave power source ( The resonance tank 12 where Vs) is applied and LLC resonates by the leakage inductor Lr, the excitation inductor Lm, and the resonance capacitor Cr, and the primary side AC power supply Vpri applied from the resonance tank 12 A transformer 13 that converts and outputs secondary side AC power (Vsec) having a voltage level according to the transformer turn ratio (n2/n1), and secondary side AC power (Vsec) output from the transformer 13 ) is provided with a rectifying unit 14 that rectifies and outputs DC output power (Vo).

At this time, the switch unit 11 may be implemented as a full bridge switching circuit 11a or a half bridge switching circuit 11b. The resonance tank 12 generally constitutes a resonance circuit by a leakage inductor (Lr), an excitation inductor (Lm), and a resonance capacitor (Cr). The transformer 13 is a component connecting the resonant tank 12 and the rectifier 14, and adjusts the output of the LLC resonant converter according to a turn ratio (n2/n1) and also provides insulation between power input and output. The rectifier 14 constitutes a full bridge, half bridge, or power factor correction bridge by a combination of a diode and a capacitor, and generates an output voltage Vo of the LLC resonant converter. In the present invention, the types of the switch unit 11 and the rectifier unit 14 are not limited.

In general, since the LLC resonant converter is capable of zero voltage switching (ZVS) of the switch unit 11 and zero current switching (ZCS) of the rectifier unit 14, high-efficiency operation is possible even at high frequencies and low noise in the output voltage. Particularly suitable for D-Class amplifiers.

On the other hand, the LLC resonant converter has a disadvantage that the output voltage rises under no-load conditions. Before the D-Class amplifier starts, there is a temporary no-load condition, and at this time, the output voltage of the LLC resonant converter rises and may cause problems. In order to prevent this, a high-capacity transformer component must be used in the transformer unit 13, which causes problems in that power loss of the D-Class amplifier increases, manufacturing cost increases, and the product becomes large and heavy.

Korean Patent Publication No. 10-2018-0129470 (2018.12.05) "Transformer and LLC resonant converter having the same" Korean Patent Publication No. 10-2018-0003122 (2018.01.09) "Interleaved LLC resonant converter and its control method" Korean Patent Registration No. 10-1204566 (2012.11.19) "Multi-output LLC resonant DC/DC converter, power supply unit and backlight unit" Korean Patent Registration No. 10-1264024 (2013.05.07) "Control circuit of LLC resonant converter and LLC resonant converter using the same" Korean Patent Registration No. 10-2191244 (2020.12.09) "LLC Resonant Converter" Republic of Korea Patent Registration No. 10-2238311 (2021.04.05) "LLC resonant converter"

An object of the present invention is generally to provide an LLC resonant converter for a D-Class amplifier.

In particular, an object of the present invention is to monitor the operating state of the D-Class amplifier, set the voltage gain of the converter low while the D-Class amplifier is running, and set the voltage gain of the converter relatively when the D-Class amplifier enters the normal state. Voltage gain variable control based D -It is to provide LLC resonant converter for class amplifier.

On the other hand, the problem of the present invention is not limited to these matters, and other problems can be understood from the description of this specification.

In order to achieve the above object, the LLC resonant converter for a D-Class amplifier based on variable voltage gain control according to the present invention is applied with a DC input power supply (Vg) and the rectangular wave power supply (Vs) by the alternating switching operation of the switching element. ) The switch unit 110 for outputting; a resonance tank 120 in which a rectangular wave power source Vs is applied from the switch unit 110 and LLC resonates by a leakage inductance Lr, an excitation inductance Lm, and a resonance capacitance Cr; As a transformer 130 for converting and outputting the primary-side AC power (Vpri) applied from the resonance tank 120 to the secondary-side AC power (Vsec) having a voltage level according to the transformer turn ratio, the primary side a pressure transformer 130 configured to provide a plurality of turn ratios by including a tap on at least one of the secondary side and the secondary side; a rectifier 140 for outputting DC output power Vo by rectifying the secondary-side AC power Vsec output from the transformer 130; By monitoring the operating state of the D-Class amplifier 150, while the D-Class amplifier 150 is running, a first voltage gain control command is generated so that the LLC resonant converter provides a preset first voltage gain, and the D-Class a voltage gain control unit 160 generating a second voltage gain control command so that the LLC resonant converter provides a preset second voltage gain greater than the first voltage gain when the amplifier 150 enters a steady state; First voltage gain control by switching and controlling at least one of the connection between the transformer 130 and the resonance tank 120 and the connection between the transformer 130 and the rectifier 140 in response to the first and second voltage gain control commands. Set the transformer 130 to provide a preset first turn ratio for the command and set the transformer 130 to provide a preset second turn ratio with a value greater than the first turn ratio for the second voltage gain control command. It may be configured to include; turn ratio setting unit 170 to.

In the present invention, the turn ratio setting unit 170 responds to the change in the excitation inductance (Lm) by switching the connection between the transformer 130 and the resonance tank 120 to satisfy the LLC resonance condition of the resonance tank 120 in the resonance tank ( 120) may be configured to control switching of the connection of the resonant capacitances Cr1 and Cr2.

In the present invention, the transformer 130 may have three taps on the secondary side -- referred to as T1, T2, and T3 in order --. At this time, the turn ratio setting unit 170 includes a first switch SW1 for switching between T1 and T2 and a second switch SW2 for switching between T2 and T3 on the secondary side of the transformer 130, and the first voltage When the gain control command is received, the first switch (SW1) is switched to T1 and the second switch (SW2) is switched to T3, and when the second voltage gain control command is received, the first switch (SW1) and the second switch ( SW2) to T2.

Also, in the present invention, the transformer 130 may include one tap T4 on the primary side. At this time, the turn ratio setting unit 170 includes a third switch SW3 for switching between the one end Tm and T4 on the primary side of the transformer 130, and when receiving the first voltage gain control command, the third switch (SW3) may be switched to Tm, and the third switch (SW3) may be switched to T4 when receiving the second voltage gain control command.

According to the present invention, it is possible to use a small-capacity transformer element in the LLC resonant converter for the D-Class amplifier, thereby reducing manufacturing cost and achieving high efficiency, light weight, and miniaturization of the product.

1] is a diagram showing a general circuit configuration of an LLC resonant converter.
[Fig. 2] is a diagram showing a voltage gain curve according to a change in frequency of an LLC resonant converter.
[Figure 3] is a diagram showing a voltage gain curve according to the output load change of the LLC resonant converter.
[Figure 4] is a diagram showing the overall configuration of the LLC resonant converter for D-Class amplifier according to the present invention.
[Fig. 5] is a diagram showing a first embodiment of an LLC resonant converter for a D-Class amplifier according to the present invention.
[Fig. 6] is a diagram showing a second embodiment of an LLC resonant converter for a D-Class amplifier according to the present invention.
[Fig. 7] is a diagram showing a third embodiment of an LLC resonant converter for a D-Class amplifier according to the present invention.
[Fig. 8] is a diagram showing a fourth embodiment of an LLC resonant converter for a D-Class amplifier according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

2 is a diagram showing a voltage gain curve according to a change in frequency of an LLC resonant converter.

In [Figure 2], Region 3 is not used to prevent component damage because it is a reverse current region. Looking at Regions 1 and 2, the operating frequency (fs) must be increased for the voltage gain to decrease, but it does not fall below a certain level (approximately 0.33). Referring to FIG. 2, it can be confirmed that it is difficult to suppress the voltage rise in the no-load state by controlling the operating frequency fs.

One approach to suppressing no-load voltage rise in an LLC resonant converter is to adjust the resonant tank 12. However, to adjust the resonant tank 12, the leakage inductance (Lk), excitation inductance (Lm), and resonant capacitance (Cr) must be changed. By changing these parameters (Lk, Lm, and Cr), the maximum This is a very sensitive issue as it can affect load behavior. For these parameters, only fine adjustment is possible, and there is not much room to suppress the no-load voltage rise through the adjustment of the resonance tank 12.

Another approach to suppressing no-load voltage rise is to adjust the transformer turn-ratio of transformer 13. However, even when changing the transformer turn ratio, since it affects the maximum load operation of the LLC resonant converter, only fine adjustment is possible. There is not much room.

Meanwhile, the LLC resonant converter has a voltage drop at maximum load as well as a voltage rise at no load. The reason why the voltage drop occurs at the maximum load is that there is a risk of component damage due to reverse current when entering Region 3. Because.

The LLC resonant converter is controlled by PFM (Pulse Frequency Modulation) method. In PFM control, when the load 15 increases, the operating frequency (fs) is lowered to increase the voltage gain to increase the output current through resonance, and the input voltage ( When Vg) increases, it works by increasing the operating frequency fs to reduce the voltage gain. Commercial LLC controllers (such as the ST L6599) are designed to do this automatically. In the maximum load condition, the operating frequency fs is lowered to compensate for the output voltage Vo by increasing the voltage gain. Even if the operating frequency fs is lowered to the lowest frequency fr2, the resonance tank 12 A voltage drop occurs in the output voltage Vo due to the limit of energy transferable through the transformer 13 and the rectifier 14 .

3 is a diagram showing a voltage gain curve according to a change in the output load of the LLC resonant converter.

The voltage gain of the LLC resonant converter shown in [Fig. 1] can be expressed as [Equation 1], and [Fig. 3] shows [Equation 1] as a graph.

3 also shows the change of the voltage gain curve according to the change of the Q factor (Quality factor). The Q factor is a value representing the sharpness of the resonance in the resonant circuit. In the LLC resonant converter, the value of the Q factor increases as the load 15 decreases. Referring to FIG. 3, as the Q value increases, the maximum voltage gain (energy accumulation rate) increases and the frequency selectivity improves, while the bandwidth narrows and the resonance sharpens.

The D-Class amplifier 15 has a property of operating with a peak load. The effective use area of the LLC resonant converter for the D-Class amplifier is the shaded part on the right side in [Fig.

In addition, comparing the operating conditions according to the change of the input voltage (Vg) under the same load condition, the lower the input voltage (Vg), the more the operating frequency (fs) is set to the lowest frequency (fr2) to increase the voltage gain. In this state, when a peak load occurs, a noticeable voltage drop occurs.

In the LLC resonant converter, when the input voltage (Vg) is fixed and a voltage drop occurs due to the load 15, a conventional approach to improve this is to increase the transformer turns ratio and use high-capacity transformer parts.

In general, to improve the voltage drop problem at maximum output (full load), the voltage gain must be increased. 2, if the voltage gain is not sufficient even in the case of operating in Region 2 at the lowest frequency (fr2), an approach to increase the transformer turn ratio (n2/n1) of the transformer 13 is taken.

However, if the voltage drop of the maximum output is improved by adjusting the transformer turn ratio, a problem arises in that the output voltage rises under no-load conditions. As a countermeasure against this, a commercial LLC controller proposes a skip mode or a burst mode. Since the LLC resonant converter for the D-Class amplifier is normally composed of one transformer component, when operated in skip mode or burst mode, a section in which the switching operation of the switch unit 11 stops occurs. In this case, the auxiliary power to drive the D-Class amplifier drops, making it impossible to start the D-Class amplifier. To solve this problem, transformer parts are used with large capacities. Due to the nature of audio output, the relationship between maximum output and average output is considered to be about 8 times. A method of connecting auxiliary power by making it in another transformer can also be considered. In this case, since power noise increases, filter capacitors and filter inductors must be added, so this also has a disadvantage.

On the other hand, it may happen that the input voltage (Vg) supplied from the outside becomes unstable. When the input voltage (Vg) of the LLC resonant converter drops, the output voltage Vo of the LLC resonant converter drops, causing problems in the operation of the D-Class amplifier. In general, if the input voltage (Vg) drops more than 10% compared to the normal state, the D-Class amplifier limits the audio output and produces a clipped sound.

4 is a diagram showing the overall configuration of the LLC resonant converter 100 for D-Class amplifier according to the present invention.

Referring to FIG. 4, the LLC resonant converter 100 is a device for supplying power to the D-Class amplifier 150, and the LLC resonant converter 100 according to the present invention includes a switch unit 110, a resonance It is configured to include a tank 120, a transformer 130, a rectification view 140, a turn ratio setting unit 170, and a voltage gain control unit 160.

In general, the D-Class amplifier 150 supplies MAIN power (+/-HV), PRE AMP power (+/-15V), and amplifier Drive IC driving power (FVCC +15V) from the LLC resonant converter (100). receive

Referring to [Fig. 1], it is known that the moment when the D-Class amplifier 15 starts in the state where the LLC resonant converter is operating due to the structure of the D-Class amplifier 15 is the most unstable state. Same as

In the conventional LLC resonant converter, a PRE AMP power supply (OP-AMP power supply) and amplifier Drive IC power supply (MOSFET GATE ON/OFF power supply) for the D-Class amplifier 15 in one transformer element provided in the transformer 13 ), etc. At this time, if the switch unit 11 of the LLC resonant converter is configured to stop switching in the middle in order to prevent an increase in output voltage in a no-load state, the MOSFET GATE voltage drops in the process of starting the D-Class amplifier 15 , AMP Drive IC operation voltage drop occurs, and D-Class amplifier 150 may fail to start normally and restart. Also, as the PRE AMP power supply becomes unstable, a sudden sound may be output to the speaker.

When the starting process is completed and the D-Class amplifier 150 enters the steady-state, the driving circuit of the D-Class amplifier 150 operates with a high side low side duty of 50%, and in this state, several Watts or more It causes power loss, so it gets out of the no-load state. Therefore, there is no need to worry about the no-load voltage rise of the LLC resonant converter in a normal state, and the no-load voltage rise of the LLC resonant converter becomes a problem while the D-Class amplifier 150 is started.

Therefore, it is important to configure the LLC resonant converter 100 so that the D-Class amplifier 150 can be stably started by supplying stable power to the D-Class amplifier 150. To this end, the LLC resonant converter 100 according to the present invention includes a switch unit 110, a resonance tank 120, a transformer 130, a rectification view 140, a voltage gain control unit 160, a turn ratio setting unit ( 170).

The LLC resonant converter 100 according to the present invention variably controls the voltage gain of the converter in response to the state information of the D-Class amplifier 150, thereby preventing instability and It has a configuration that can solve all the problems of the prior art of the maximum output performance of the D-Class amplifier 150 due to the maximum load voltage drop. To this end, the LLC resonant converter 100 is configured to switch the connection between the transformer 130 and the resonance tank 120 or the rectifier 140, and the voltage gain control unit 160 connects the D-Class amplifier 150 By monitoring the operating state of the converter, the voltage gain of the converter is set low while the D-Class amplifier 150 is running, and the voltage gain of the converter is set higher when the D-Class amplifier 150 enters a normal state.

First, the switch unit 110 is a component that outputs a rectangular waveform power source Vs by an alternating switching operation of a switching element when a DC input power source Vg is applied.

The resonance tank 120 is a component that LLC resonates by a leakage inductance Lr, an excitation inductance Lm, and a resonance capacitance Cr when a rectangular wave power source Vs is applied from the switch unit 110.

The transformer 130 is a component that boosts or lowers the primary side AC power Vpri applied from the resonance tank 120 to convert and output the secondary side AC power Vsec. At this time, the secondary-side AC power supply Vsec has a voltage level obtained by boosting or lowering the primary-side AC power supply Vpri by a turn-ratio of a transformer element inside the transformer 130. As shown in [Figs. 5] to [Fig. 8], the transformer 130 is configured to provide a plurality of turn ratios by providing a tap on at least one of the primary side and the secondary side.

The rectification view 140 is a component that outputs DC output power Vo by rectifying the secondary side AC power Vsec output from the transformer 130 .

The voltage gain controller 160 monitors the operating state of the D-Class amplifier 150 and controls the LLC resonant converter 100 to show a low voltage gain while the D-Class amplifier 150 is operating, and When the amplifier 150 enters a steady state, it is a component that controls the LLC resonant converter 100 to exhibit a relatively higher voltage gain. To this end, the voltage gain controller 160 issues a first voltage gain control command so that the LLC resonant converter 100 exhibits a low voltage gain ('first voltage gain') while the D-Class amplifier 150 is operating. and generates a second voltage gain control command so that the LLC resonant converter 100 exhibits a relatively higher voltage gain ('second voltage gain') when the D-Class amplifier 150 enters a steady state .

At this time, various configurations are possible for the voltage gain control unit 160 to identify whether the D-Class amplifier 150 is in a starting state or has entered a normal state.

First, it is possible to use a terminal for status display provided in a commercial AMP IC. Most commercial AMP ICs have a status display terminal, which indicates whether the D-Class amplifier 150 is in a normal state or in protection operation by a high or low level. Therefore, the voltage gain controller 160 determines whether the D-Class amplifier 150 is operating or normal depending on whether the status display terminal of the AMP IC included in the D-Class amplifier 150 is a high level or a low level. You can identify whether you have entered the state.

Second, a method using a soft start terminal provided in a commercial AMP IC is also possible. When the D-Class amplifier 150 is in a normal state, the soft start terminal maintains a voltage level above a certain level. Therefore, the voltage gain control unit 160 determines whether the D-Class amplifier 150 is operating or normal depending on whether the soft-start terminal of the AMP IC included in the D-Class amplifier 150 has a voltage level above a certain level. entry can be identified.

Thirdly, the voltage gain controller 160 detects the state of the gate voltage (Vgs) and the drain-source voltage (Vds) of the power switching device (MOSFET) included in the D-Class amplifier 150 to detect the state of the D-Class amplifier ( It is also possible to identify whether 150) is in a starting state or has entered a normal state.

The turn ratio setting unit 170 sets the transformer turn ratio of the transformer 130 in response to the voltage gain control command generated by the voltage gain control unit 160, and additionally sets the resonance condition of the resonance tank 120 if necessary. do.

To this end, the turn ratio setting unit 170 switches and controls at least one of the connection between the transformer 130 and the resonance tank 120 and the connection between the transformer 130 and the rectifier 140 . By such switching control, the effective connection of the tap existing on at least one of the primary side and the secondary side of the transformer 130 is changed, and accordingly, the transformer turn ratio of the transformer 130 is changed. Upon receiving the first voltage gain control command corresponding to the low voltage gain of the converter, the turn ratio setting unit 170 sets the transformer 130 to provide a low turn ratio ('first turn ratio') through connection switching. Upon receiving the second voltage gain control command corresponding to the higher voltage gain, the turn ratio setting unit 170 sets the transformer 130 to provide a relatively higher turn ratio ('second turn ratio') through connection switching. do.

At this time, when the connection between the transformer 130 and the resonance tank 120 is switched to change the transformer turn ratio of the transformer 130, the excitation inductance Lm is changed so that the LLC resonance condition of the resonance tank 120 is changed. There is a risk of breaking. Accordingly, when the excitation inductance Lm is changed by switching the connection between the transformer 130 and the resonance tank 120, the turn ratio setting unit 170 responds to the change in the excitation inductance Lm to the resonance tank ( 120) is controlled to satisfy the LLC resonance condition of the resonance tank 120 by switching the connection of the resonance capacitances Cr1 and Cr2.

Meanwhile, the switching circuit of the turn ratio setting unit 170 may be implemented using a relay, MOSFET, IGBT, or the like.

[Fig. 5] (a) is a diagram showing the first embodiment of the LLC resonant converter 100 for D-Class amplifier according to the present invention, [Fig. 5] (b) and (c) are the first embodiment of the present invention It is a diagram showing the voltage gain control operation in the first embodiment.

The first embodiment of FIG. 5 is a method of switching the secondary side tap connection of the transformer 130 in response to the operating state of the D-Class amplifier 150. The transformer turns ratio of the transformer 130 is changed by the switching of the secondary side tap connection, and the voltage gain of the LLC resonant converter 100 is also changed accordingly.

To this end, the transformer 130 has three taps on the secondary side, and for convenience, they are sequentially denoted as T1, T2, and T3. Further, the turn ratio setting unit 170 includes a first switch SW1 for switching between T1 and T2 and a second switch SW2 for switching between T2 and T3 on the secondary side of the transformer 130 .

When the D-Class amplifier 150 starts up for the first time, the turn ratio setting unit 170 turns on the first switch SW1 according to the first voltage gain control command of the voltage gain control unit 160 as shown in FIG. 5 (b). Switching to T1 and switching the second switch (SW2) to T3 establishes the secondary side tap connection. In this case, the transformer turn ratio of the transformer 130 is N: (M1 + M4).

When the D-Class amplifier 150 enters the normal state, the turn ratio setting unit 170 operates according to the second voltage gain control command of the voltage gain control unit 160 by the first switch SW1 as shown in [Fig. and the second switch (SW2) are switched to T2 to set the secondary side tap connection. In this case, the transformer turn ratio of the transformer 130 is N: (M1 + M2 + M3 + M4).

Therefore, the transformer 130 shows a low turn ratio (ie, (M1+M4)/N) when the D-Class amplifier 150 first starts, and when the D-Class amplifier 150 enters the normal state, the relative is set to indicate a higher turns ratio (ie, (M1+M2+M3+M4)/N).

At this time, the turn ratio of M2 and M3 can be selected through the operation analysis of the D-Class amplifier 150, and 1 to 3 turns are appropriate in experience.

[Fig. 6] (a) is a diagram showing the second embodiment of the LLC resonant converter 100 for D-Class amplifier according to the present invention, [Fig. 6] (b) and (c) are the second embodiment of the present invention It is a diagram showing voltage gain control operation in the second embodiment.

The second embodiment of [FIG. 6] is a method of switching the primary-side tap connection of the transformer 130 in response to the operating state of the D-Class amplifier 150. The transformer turn ratio of the transformer 130 is changed by the switching of the primary side tap connection, and the voltage gain of the LLC resonant converter 100 is also changed accordingly. To this end, the transformer 130 includes one tap T4 on the primary side, and the turn ratio setting unit 170 switches between the one end Tm and T4 on the primary side of the transformer 130. A switch (SW3) is provided.

When the D-Class amplifier 150 starts up for the first time, the turn ratio setting unit 170 turns on the third switch SW3 according to the first voltage gain control command of the voltage gain control unit 160 as shown in [Fig. 6] (b). By switching to Tm, the primary side tap connection is established. In this case, the transformer turn ratio of the transformer 130 is (N1+N2) : M.

When the D-Class amplifier 150 enters the normal state, the turn ratio setting unit 170 operates according to the second voltage gain control command of the voltage gain control unit 160 as shown in [Fig. is switched to T4 to establish a primary-side tap connection. In this case, the transformer turn ratio of the transformer 130 is N2:M.

Therefore, the transformer 130 shows a low turn ratio (ie, M/(N1+N2)) when the D-Class amplifier 150 first starts, and when the D-Class amplifier 150 enters the normal state, the relative is set to indicate a higher turns ratio (i.e., M/N2).

Since the sound source of the D-Class amplifier 150 must have +/- voltage, the effect of raising 2 turns on the secondary side in the transformer 130 is the same as the effect of raising 1 turn on the primary side. That is, the method of adjusting the primary-side turns ratio has a greater effect on the voltage gain of the LLC resonant converter 100 than the method of adjusting the secondary-side turns ratio. As the output voltage of the D-Class amplifier 150 increases, the power consumption of the D-Class amplifier 150 in a standby state without an audio signal increases. ), the primary side turn ratio adjustment of [Fig. 6] is more effective than the secondary side turn ratio adjustment method of [Fig. 5].

[Fig. 7] (a) is a diagram showing the third embodiment of the LLC resonant converter 100 for D-Class amplifier according to the present invention, [Fig. 7] (b) and (c) are the diagrams of the present invention It is a diagram showing the voltage gain control operation in the third embodiment.

The third embodiment of [Fig. 7] is different from the second embodiment of [Fig. Common

When the primary-side turn ratio change in the transformer 130 becomes greater than a predetermined threshold value, the LLC resonance condition of the resonance tank 120 may be broken due to the change in excitation inductance Lm. In the third embodiment, in order to maintain the LLC resonance condition before and after the switching operation of the turn ratio setting unit 170, the turn ratio setting unit 170 synchronizes (syncs) with the operation of switching the transformer turn ratio of the transformer 130 to resonate the tank. In 120, the connection of the resonance capacitances Cr1 and Cr2 is also switched and controlled. That is, the LLC resonance condition of the resonance tank 120 is maintained by changing the resonance capacitance (Cr) to correspond to the change of the excitation inductance (Lm).

If the third embodiment is used, it is possible to operate both in the 100 to 120 [Vac] region and the 220 to 240 [Vac] region without any manipulation without a power factor correction (PFC) boost converter. That is, it is possible to ensure stable output by detecting the voltage level of the input voltage (Vgs) according to the commercial power source, determining the voltage specification of other countries, and operating the path switch of the turn ratio setting unit 170 in response thereto.

8 is a diagram showing a fourth embodiment of an LLC resonant converter 100 for a D-Class amplifier according to the present invention.

The fourth embodiment of [Fig. 8] combines the first embodiment of [Fig. 5] and the second embodiment of [Fig. 6]. Rather than adjusting only one of the primary and secondary side turn ratios of the transformer 130, when both the primary and secondary turn ratios are adjusted, various voltage gains can be adjusted, and thus system stability can be obtained. A first turn ratio setting unit 170a is provided to adjust the primary side turn ratio of the transformer 130, and a second turn ratio setting unit 170b is provided to adjust the secondary side turn ratio of the transformer 130. there is.

100: LLC resonant converter
110: switch unit
120: resonance tank
130: transformer unit
140: rectification view
150 : D-Class Amplifier
160: voltage gain controller
170: turn ratio setting unit

Claims (4)

a switch unit 110 for outputting rectangular wave power (Vs) by an alternating switching operation of a switching element to which DC input power (Vg) is applied;
a resonance tank 120 in which a rectangular wave power source Vs is applied from the switch unit 110 and LLC resonates by a leakage inductance Lr, an excitation inductance Lm, and a resonance capacitance Cr;
The transformer 130 converts the primary side AC power Vpri applied from the resonance tank 120 into the secondary side AC power Vsec having a voltage level according to the transformer turn ratio, and outputs the voltage, at least one A transformer 130 configured to provide a plurality of turn ratios by having a tap T4 on the primary side -- The transformer 130 also includes three taps T1, T2, and T3 on the secondary side. have --;
a rectifier 140 for outputting DC output power Vo by rectifying the secondary side AC power Vsec output from the transformer 130;
By monitoring the operating state of the D-Class amplifier 150, while the D-Class amplifier 150 is operating, a first voltage gain control command is generated so that the LLC resonant converter provides a preset first voltage gain, and the D-Class amplifier 150 generates a first voltage gain control command. - When the class amplifier 150 enters a steady state, a voltage gain control unit 160 for generating a second voltage gain control command so that the LLC resonant converter provides a second voltage gain preset as a value greater than the first voltage gain );
In response to the first and second voltage gain control commands, the excitation inductance (Lm) is changed by switching and controlling the connection between the transformer 130 and the resonance tank 120, and the first and second voltages The transformer turns ratio is changed by switching and controlling the connection between the transformer 130 and the rectifier 140 in response to a gain control command, and the resonance tank 120 responds to the change in the excitation inductance Lm. Turn ratio setting unit 170 for switching and controlling the connection of the resonance capacitances (Cr1, Cr2) of the resonance tank 120 in synchronization with the change of the transformer turn ratio so that the LLC resonance condition of is maintained--the transformer ( 130) and the resonance tank 120 includes the connection between the T4 and the resonance tank 120, and the change of the transformer turn ratio sets a preset first turn ratio for the first voltage gain control command. Setting the transformer 130 to provide and setting the transformer 130 to provide a second turn ratio preset as a value greater than the first turn ratio for the second voltage gain control command - -;
The turn ratio setting unit 170 includes a first switch SW1 for switching between T1 and T2 and a second switch SW2 for switching between T2 and T3 on the secondary side of the transformer 130. ), and when the first voltage gain control command is received, the first switch SW1 is switched to T1, the second switch SW2 is switched to T3, and the second voltage gain control command is issued. When received, the first switch SW1 and the second switch SW2 are switched to T2 to switch the connection between the transformer 130 and the rectifier 140, and the turn ratio setting unit 170 ) also includes a third switch (SW3) for switching between the one end (Tm) and the T4 on the primary side of the transformer 130, and when receiving the first voltage gain control command, the third switch (SW3) ) to the Tm, and when the second voltage gain control command is received, the third switch (SW3) is switched to the T4 to switch the connection between the T4 and the resonance tank 120. LLC resonant converter for D-Class amplifier based on variable voltage gain control. delete delete delete

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