Patent ID: 12224672

DETAILED DESCRIPTION

Reference will now be made to the drawing figures to describe the present disclosure in detail. It will be understood that the drawing figures and exemplified embodiments of present disclosure are not limited to the details thereof.

Please refer toFIG.1, which shows an architecture block diagram of an asymmetric power converter according to the present disclosure. The asymmetric power converter includes a primary-side rectifying/filtering circuit1, a power factor correction circuit2, an asymmetric conversion circuit3, and a feedback control circuit4.

The primary-side rectifying/filtering circuit1rectifies and filters an input voltage VACinto a first voltage V1. The power factor correction circuit2is coupled to the primary-side rectifying/filtering circuit1, and receives the first voltage V1and converts the first voltage V1into a power voltage VP.

The asymmetric conversion circuit3is coupled to the power factor correction circuit2, and receives the power voltage VPand converts the power voltage VPinto an output voltage VOto supply power to a load5. Therefore, the load5is supplied power by the output voltage VOand an output current IOis drawn by the load5. For example, the output current IOof 2 amps is drawn.

The feedback control circuit4is coupled to the asymmetric conversion circuit3, and generates a feedback control signal SFaccording to a load power demand provided by the load5. In particular, the load power demand includes information of the output voltage VOand information of the output current IO. Specifically, the load5may feed back the magnitude of the supplied output voltage VOand the drawn output current IOto the feedback control circuit4. Therefore, the feedback control circuit4provides the feedback control signal SFincluding the information of the output voltage VOand the information of the output current IOto the asymmetric conversion circuit3.

Therefore, the feedback control circuit4controls the asymmetric conversion circuit3to operate in a full-bridge resonant mode, a half-bridge resonant mode, or a hybrid half-bridge resonant mode according to the feedback control signal SF. Various operation modes will be described in more detail later.

Please refer toFIG.2A, which shows a circuit diagram of a power factor correction circuit according to a first embodiment of the present disclosure. In the first embodiment, components of the power factor correction circuit2correspond to one waveform (polarity) design of the first voltage V1. Specifically, the power factor correction circuit2includes a first switch21, a first inductor22, a first diode23, a first capacitor24, and a first resistor25. A first end of the first switch21is coupled to a first end of the first voltage V1. A first end of the first inductor22is coupled to a second end of the first switch21, and a second end of the first inductor22is coupled to a second end of the first voltage V1. A first end of the first diode23is coupled to the first end of the first inductor22. A first end of the first capacitor24is coupled to a second end of the first diode23, and a second end of the first capacitor24is coupled to the second end of the first inductor22. A first end of the first resistor25is coupled to the first end of the first capacitor24, and a second end of the first resistor25is coupled to the second end of the first capacitor24. The first switch21is controlled to switching according to the switching frequency so as to convert the first voltage V1into the power voltage VP.

Please refer toFIG.2B, which shows a circuit diagram of the power factor correction circuit according to a second embodiment of the present disclosure. Compared with the embodiment ofFIG.2A, in the second embodiment, components of the power factor correction circuit2correspond to another waveform (polarity) design of the first voltage V1. Specifically, the power factor correction circuit2includes a first inductor22, a first switch21, a first diode23, a first capacitor24, and a first resistor25. A first end of the first inductor22is coupled to a first end of the first voltage V1. A first end of the first switch21is coupled to a second end of the first inductor22, and a second end of the first switch21is coupled to a second end of the first voltage V1. A first end of the first diode23is coupled to the first end of the first switch21. A first end of the first capacitor24is coupled to a second end of the first diode23, and a second end of the first capacitor24is coupled to the second end of the first switch21. A first end of the first resistor25is coupled to the first end of the first capacitor24, and a second end of the first resistor25is coupled to the second end of the first capacitor24. The first switch21is controlled to switching according to the switching frequency so as to convert the first voltage V1into the power voltage VP.

Please refer toFIG.3, which shows a circuit diagram of an asymmetric conversion circuit according to the present disclosure; please refer toFIG.4A, which shows a circuit diagram of a primary-side isolation circuit of the asymmetric conversion circuit shown inFIG.3according to the present disclosure; please refer toFIG.4B, which shows a circuit diagram of a secondary-side isolation circuit of the asymmetric conversion circuit shown inFIG.3according to the present disclosure. The asymmetric conversion circuit3includes a primary-side isolation circuit31(shown inFIG.4A) and a secondary-side isolation circuit32(shown inFIG.4B). The primary-side isolation circuit31includes a bridge synchronous rectification circuit311to receive the feedback control signal SFand the power voltage VP. The secondary-side isolation circuit32includes a bridge switching circuit321and a resonant circuit322to convert the power voltage VPinto the output voltage VO.

As shown inFIG.4A, the bridge synchronous rectification circuit311includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a first resonant inductor Lr, a first resonant capacitor Cr, and a second resonant inductor Lm. A first end of the second switch Q2is coupled to a second end of the first switch Q1. A first end of the third switch Q3is coupled to a first end of the first switch Q1. A first end of the fourth switch Q4is coupled to a second end of the third switch Q3, and a second end of the fourth switch Q4is coupled to a second end of the second switch Q2. The first resonant capacitor Cr is coupled to the first resonant inductor Lr in series to form a series-connected branch, and a first end of the series-connected branch is coupled to the second end of the first switch Q1and the first end of the second switch Q2. A first end of the second resonant inductor Lm is coupled to a second end of the series-connected branch, and a second end of the second resonant inductor Lm is coupled to the second end of the third switch Q3and the first end of the fourth switch Q4. The feedback control circuit4controls the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4according to the feedback control signal SF. As shown inFIG.4B, the bridge switching circuit321includes an upper switch D1. The resonant circuit322includes a capacitor Co and a resistor Ro to form a parallel-connected branch, and the parallel-connected branch is coupled to the upper switch D1.

The asymmetric conversion circuit3of the present disclosure operates in the full-bridge resonant mode, the half-bridge resonant mode, or the hybrid half-bridge resonant mode as follows.

When the output voltage VOis greater than a threshold voltage, the asymmetric conversion circuit3operates in the full-bridge resonant mode. Specifically, when the feedback control circuit4determines that the output voltage VOis greater than a threshold voltage, since the feedback control signal SFincludes the information of the output voltage VOand the information of the output current IO, the feedback control signal SFgenerated by the feedback control circuit4is used to control the asymmetric conversion circuit3to operate in the full-bridge resonant mode.

According to the feedback control signal SF, in the full-bridge resonant mode, the feedback control circuit4controls the first switch Q1and the fourth switch Q4to be simultaneously turned on or turned off, the second switch Q2and the third switch Q3to be simultaneously turned on or turned off, and the first switch Q1and the second switch Q2to be complemently switched so as to convert the power voltage VPinto the output voltage VO. Incidentally, the feedback control circuit4provides a first control signal S1to control the first switch Q1, provides a second control signal S2to control the second switch Q2, provides a third control signal S3to control the third switch Q3, and provides a fourth control signal S4to control the fourth switch Q4.

Please refer toFIG.5A, which shows a schematic waveform of operating the asymmetric conversion circuit under a flyback conversion operation in a full-bridge resonant mode according to the present disclosure, and also refer toFIG.3. Under this operation, the first switch Q1and the fourth switch Q4are first turned on, and then the second switch Q2and the third switch Q3are turned on, and the operation is continuously repeated to form a flyback conversion operation. Specifically, when the first switch Q1and the fourth switch Q4are first turned on, a current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on (the first switch Q1and the fourth switch Q4are turned off) to keep an inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components (including the first resonant inductor Lr, the first resonant capacitor Cr, and the second resonant inductor Lm) is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the third switch Q3, the formed sine wave flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on (the second switch Q2and the third switch Q3are turned off) to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Please refer toFIG.5B, which shows a schematic waveform of operating the asymmetric conversion circuit under a forward conversion operation in the full-bridge resonant mode according to the present disclosure, and also refer toFIG.3. Under this operation, the second switch Q2and the third switch Q3are first turned on, and then the first switch Q1and the fourth switch Q4are turned on, and the operation is continuously repeated to form a forward conversion operation. Specifically, when the second switch Q2and the third switch Q3are first turned on, a current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, energy is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the fourth switch Q4, the formed sine wave flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, the energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

When the output voltage VOis less than the threshold voltage and the output current IOis less than a threshold current, the asymmetric conversion circuit3operates in the half-bridge resonant mode. According to the feedback control signal SF, in the half-bridge resonant mode, the feedback control circuit4controls the first switch Q1and the second switch Q2to be complemently switched, and the third switch Q3and the fourth switch Q4to be complemently turned on and turned off so as to convert the power voltage VPinto the output voltage VO. Alternatively, the feedback control circuit4controls the first switch Q1and the second switch Q2to be complemently turned on and turned off, and the third switch Q3and the fourth switch Q4to be complemently switched so as to convert the power voltage VPinto the output voltage VO.

Please refer toFIG.6A, which shows a schematic waveform of operating the asymmetric conversion circuit under the flyback conversion operation in a half-bridge resonant mode according to a first embodiment of the present disclosure, and also refer toFIG.3. Under this operation, the first switch Q1is first turned on, and then the second switch Q2is switched on to be complemently switched, and the third switch Q3is turned on (high level) and the fourth switch Q4is turned off (low level), and the operation is continuously repeated to form a flyback conversion operation. Specifically, when the first switch Q1and the fourth switch Q4are first turned on, a current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the fourth switch Q4are then turned on to keep an inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the fourth switch Q4, the formed sine wave flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Please refer toFIG.6, which shows a schematic waveform of operating the asymmetric conversion circuit under the flyback conversion operation in the half-bridge resonant mode according to a second embodiment of the present disclosure, and also refer toFIG.3. Under this operation, the fourth switch Q4is first turned on, and then the third switch Q3is switched on to be complemently switched, and the first switch Q1is turned on (high level) and the second switch Q2is turned off (low level), and the operation is continuously repeated to form a flyback conversion operation. Specifically, when the first switch Q1and the fourth switch Q4are first turned on, a current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the first switch Q1and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the third switch Q3, the formed sine wave flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Please refer toFIG.7A, which shows a schematic waveform of operating the asymmetric conversion circuit under the forward conversion operation in the half-bridge resonant mode according to a first embodiment of the present disclosure, and also refer toFIG.3. Under this operation, the second switch Q2is first turned on, and then the first switch Q1is switched on to be complemently switched, and the third switch Q3is turned on (high level) and the fourth switch Q4is turned off (low level), and the operation is continuously repeated to form a forward conversion operation. Specifically, when the second switch Q2and the third switch Q3are first turned on, a current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, energy is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the third switch Q3, the formed sine wave flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Please refer toFIG.7B, which shows a schematic waveform of operating the asymmetric conversion circuit under the forward conversion operation in the half-bridge resonant mode according to a second embodiment of the present disclosure, and also refer toFIG.3. Under this operation, the third switch Q3is first turned on, and then the fourth switch Q4is switched on to be complemently switched, and the second switch Q2is turned on and the first switch Q1is turned off, and the operation is continuously repeated to form a forward conversion operation. Specifically, when the second switch Q2and the third switch Q3are first turned on, a current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, energy is transmitted to the secondary side of the transformer.

Afterward, the second switch Q2and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the fourth switch Q4, the formed sine wave flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, the energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

When the output voltage VOis less than the threshold voltage and the output current IOis greater than the threshold current, the asymmetric conversion circuit3operates in the hybrid half-bridge resonant mode. According to the feedback control signal SF, in the hybrid half-bridge resonant mode, the feedback control circuit4controls the first switch Q1and the second switch Q2to be partially complemently switched and partially complemently turned on and turned off, and the third switch Q3and the fourth switch Q4to be correspondingly partially complemently turned on and turned off and correspondingly partially complemently switched to convert the power voltage VPinto the output voltage VO.

Please refer toFIG.8A, which shows a schematic waveform of operating the asymmetric conversion circuit under the flyback conversion operation in a hybrid half-bridge resonant mode according to the present disclosure, and also refer toFIG.3. Under this operation, the first switch Q1and the second switch Q2are first complemently switched and then complemently turned on and turned off, and the third switch Q3and the fourth switch Q4are correspondingly first complemently turned on and turned off and then correspondingly complemently switched, and the operation is continuously repeated to form a flyback conversion operation. Specifically, when the first switch Q1and the fourth switch Q4are first turned on, a current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the fourth switch Q4, the formed sine wave flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the fourth switch Q4, the formed sine wave flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the first switch Q1and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the third switch Q3, the formed sine wave flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Please refer toFIG.8B, which shows a schematic waveform of operating the asymmetric conversion circuit under the forward conversion operation in the hybrid half-bridge resonant mode according to the present disclosure, and also refer toFIG.3. Under this operation, the third switch Q3and the fourth switch Q4are first complemently switched and then complemently turned on and turned off, and the first switch Q1and the second switch Q2are correspondingly first complemently turned on and turned off and then correspondingly complemently switched, and the operation is continuously repeated to form a forward conversion operation. Specifically, when the second switch Q2and the third switch Q3are first turned on, a current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the first switch Q1and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the first switch Q1. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the first switch Q1and the third switch Q3, the formed sine wave flows through the first switch Q1, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the third switch Q3, the formed sine wave flows through the third switch Q3, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy stored in the transformer is transmitted to the secondary side of the transformer.

Afterward, the second switch Q2and the fourth switch Q4are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the fourth switch Q4, the second resonant inductor Lm, the first resonant inductor Lr, the first resonant capacitor Cr, and the second switch Q2. In this condition, the energy is continuously transmitted to the secondary side of the transformer.

Afterward, the resonance operation of the resonant components is executed to implement zero-voltage switching (ZVS) and/or zero-current switching (ZCS). Therefore, under the turning on of the second switch Q2and the fourth switch Q4, the formed sine wave flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the fourth switch Q4. In this condition, the energy is stored in the transformer (at the primary side) of the power converter.

Afterward, the second switch Q2and the third switch Q3are then turned on to keep the inductor current of the transformer freewheeling. The current inside the bridge synchronous rectification circuit311flows through the second switch Q2, the first resonant capacitor Cr, the first resonant inductor Lr, the second resonant inductor Lm, and the third switch Q3. In this condition, the energy is still stored in the transformer (at the primary side) of the power converter.

In summary, the present disclosure has the following features and advantages:1. According to the output voltage and output current, the feedback control circuit controls the asymmetric conversion circuit to operate in the full-bridge resonant mode, the half-bridge resonant mode, or the hybrid half-bridge resonant mode according to the feedback control signal.2. By operating in the different operation modes achieves the required voltage gain ratio, and the conversion between high wattage and low wattage requirements, thereby increasing the operation cycle range.3. The full-bridge mode is used at higher wattages, and the half-bridge mode is used at lower wattages to reduce switching losses at lower wattages.4. Uniform distribution of switching losses can be implemented by operating the asymmetric conversion circuit in the half-bridge resonant mode and the hybrid half-bridge resonant mode.

Although the present disclosure has been described with reference to the preferred embodiment thereof, it will be understood that the present disclosure is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the present disclosure as defined in the appended claims.