Zero voltage switching hybrid converter

Abstract

The invention discloses a non-isolated DC-DC (Direct Current-Direct Current) switch hybrid converter which is realized by using a cross-coupled series capacitor quadruple buck converter topology. In some embodiments, a DC-DC switching hybrid converter includes a switched capacitor converter circuit, and incorporates a coupled inductor for implementing a soft switching zero voltage switching network, and for implementing a fixed step-down ratio. The hybrid converter can support high step-down ratios (e.g., 8: 1) while providing high efficiency. In other embodiments, a DC-DC switching hybrid converter introduces a transformer instead of a coupled inductor in order to further increase the step-down ratio.

Description

TECHNICAL FIELD

[0001] The present invention relates to DC-DC converters, and in particular to a DC-DC switched hybrid converter with a fixed step-down ratio. BACKGROUND

[0002] Power distribution systems for telecommunications and data networking systems have transitioned from a centralized power supply to a distributed power supply architecture. In the distributed power supply architecture, an AC / DC front-end power supply generates a 48V backplane voltage that is distributed to each rack or line card of the system, which is stepped down to a low-level supply voltage by a distributed DC / DC converter on each rack or line card. Recently, an intermediate bus architecture (IBA) has been developed for server and data communications applications in which the low-level supply voltage can range from 0.5V to 3.3V. In an IBA power supply system, a front-end AC / DC power supply provides a 48V backplane voltage, which is provided to an intermediate bus converter (IBC). The IBC converts the 48V backplane voltage to an intermediate bus voltage, typically 5-14V. The intermediate bus voltage is then provided to a point-of-load regulator in order to provide high quality voltage at a lower supply voltage value, e.g., 0.5-3.3V.

[0003] As the power demands of increasingly powerful processors in servers or data centers increase, the IBC must meet higher efficiency and power density requirements. Achieving high efficiency is particularly important in cases where the IBA power supply system is implemented with a high step-down ratio. SUMMARY

[0004] It is an object of the present invention to provide a DC-DC switched hybrid converter to support a high step-down ratio while providing high efficiency.

[0005] To achieve the above object, the present invention provides a DC-DC switched hybrid converter that receives an input voltage and generates an output voltage having a substantially constant amplitude at an output node, comprising: a switched capacitor converter circuit including a set of switches configured to provide a fixed M: 1 step-down ratio between the input voltage and the output voltage; a first capacitor coupled between a first node and a second node, the first node being switchably coupled to the input voltage, the second node being switchably coupled to a ground potential; a second capacitor and a third capacitor coupled to the set of switches in a cross-coupled configuration; a first inductor and a second inductor, the first terminal of the first inductor and the second inductor being coupled to the output node, the first inductor and the second inductor being configured to couple inductors; and a zero voltage switching network coupled between the second node and the ground potential to discharge voltage on certain switches between switching states of the hybrid converter. The hybrid converter generates the output voltage at the output node as 1 / M of the input voltage.

[0006] Optionally, the plurality of switches of the switched capacitor converter circuit comprises:

[0007] a first switch, a second switch, a third switch and a fourth switch connected in series between an input voltage and a ground potential, a first node being located between the first switch and the second switch; and

[0008] a fifth switch, a sixth switch, a seventh switch and an eighth switch connected in series with each other, wherein the fifth switch and the eighth switch have their terminal terminals connected to the ground potential, a second node being located between the fifth switch and the sixth switch,

[0009] wherein a first terminal of the second capacitor is coupled to a third node, the third node being located between the second switch and the third switch, a second terminal of the second capacitor is coupled to a fourth node, the fourth node being located between the seventh switch and the eighth switch; a first terminal of the third capacitor is coupled to a fifth node, the fifth node being located between the sixth switch and the seventh switch, a second terminal of the third capacitor is coupled to a sixth node, the sixth node being located between the third switch and the fourth switch; and

[0010] wherein a first terminal of the first inductor is coupled to the output node, a second terminal is coupled to the sixth node; a first terminal of the second inductor is coupled to the output node, a second terminal is coupled to the fourth node.

[0011] Optionally, the hybrid converter is controlled by clock signals having a first clock frequency, each clock signal period defining a switching period; and wherein the first switch, the third switch, the sixth switch and the eighth switch are controlled by a first control signal, the second switch, the fourth switch, the fifth switch and the seventh switch are controlled by a second control signal; in each switching period, the first control signal has a first duty cycle corresponding to a first switching state to turn on the first, third, sixth and eighth switches, the second control signal has a second duty cycle corresponding to a second switching state to turn on the second, fourth, fifth and seventh switches, the first duty cycle and the second duty cycle do not overlap.

[0012] Optionally, the first duty cycle and the second duty cycle have substantially equal durations in each switching period.

[0013] Optionally, the zero voltage switching network discharges the first switch, the second switch, the fifth switch and the sixth switch in a time period between the first switching state and the second switching state so as to achieve zero voltage switching on the switches.

[0014] Optionally, the zero voltage switching network comprises a fourth capacitor and a third inductor connected in series between the second node and the ground potential.

[0015] Optionally, the first inductor and the second inductor have the same voltage value in the first switching state and the same voltage value in the second switching state.

[0016] Optionally, the first switch to the eighth switch each comprises an N-type MOSFET, the first control signal is coupled to a gate terminal of the N-type MOSFET forming the first switch, the third switch, the sixth switch and the eighth switch so as to turn on and turn off the N-type MOSFET, the second control signal is coupled to a gate terminal of the N-type MOSFET forming the second switch, the fourth switch, the fifth switch and the seventh switch so as to turn on and turn off the N-type MOSFET.

[0017] Optionally, during the first duty cycle, the inductive current of the first inductor increases, and the inductive current of the second inductor decreases; during the second duty cycle, the inductive current of the first inductor decreases, and the inductive current of the second inductor increases.

[0018] Optionally, the second capacitor and the third capacitor have the same capacitance value, and the first inductor and the second inductor have the same inductance value.

[0019] Optionally, the buck converter has a fixed 8:1 buck ratio. In another embodiment, a DC-DC switched hybrid converter receives an input voltage and generates an output voltage having a substantially constant amplitude at an output node, comprising: a switched capacitor converter circuit including a set of switches configured to provide a fixed M:1 buck ratio between the input voltage and the output voltage; a first capacitor coupled between a first node and a second node, the first node being switchably coupled to the input voltage, the second node being switchably coupled to a ground potential; a second capacitor and a third capacitor coupled to the set of switches in a cross-coupled configuration; a transformer including a first primary winding and a second primary winding inductively coupled to a first secondary winding and a second secondary winding, a center tap of the first primary winding and the second primary winding being coupled to the second capacitor and the third capacitor, respectively, a turns ratio of the first primary winding to the first secondary winding being N1 / N2; a turns ratio of the second primary winding to the second secondary winding being N1 / N2; and a zero voltage switching network coupled between the second node and the ground potential so as to discharge voltage on certain switches between switching states of the hybrid converter. The hybrid converter generates the output voltage at the output node, the buck value of which is determined by the fixed buck ratio M:1 and the turns ratio N1 / N2 of the transformer.

[0020] Optionally, the plurality of switches of the switched capacitor converter circuit comprises:

[0021] a first switch, a second switch, a third switch and a fourth switch connected in series between the input voltage and the ground potential, the first node being located between the first switch and the second switch; and

[0022] The fifth switch, the sixth switch, the seventh switch and the eighth switch are connected in series with each other, terminal terminals of the fifth switch and the eighth switch are connected to a ground potential respectively, and the second node is located between the fifth switch and the sixth switch,

[0023] The first terminal of the second capacitor is coupled to a third node, the third node is located between the second switch and the third switch, and the second terminal of the second capacitor is coupled to a second center tap of the second primary winding; the first terminal of the third capacitor is coupled to a fifth node, the fifth node is located between the sixth switch and the seventh switch, and the second terminal of the third capacitor is coupled to a first center tap of the first primary winding; and

[0024] The first primary winding of the transformer is connected in series with the first secondary winding at a sixth node between the third switch and the fourth switch; the second primary winding of the transformer is connected in series with the second secondary winding at a fourth node between the seventh switch and the eighth switch, the first secondary winding and the second secondary winding are connected in series between the sixth node and the fourth node, and center taps of the first secondary winding and the second secondary winding are an output node for providing an output voltage.

[0025] Optionally, the hybrid converter is controlled by clock signals having a first clock frequency, each clock signal period defining a switching period; and wherein the first switch, the third switch, the sixth switch and the eighth switch are controlled by a first control signal, and the second switch, the fourth switch, the fifth switch and the seventh switch are controlled by a second control signal; in each switching period, the first control signal has a first duty cycle corresponding to a first switch state to turn on the first switch, the third switch, the sixth switch and the eighth switch, and the second control signal has a second duty cycle corresponding to a second switch state to turn on the second switch, the fourth switch, the fifth switch and the seventh switch, the first duty cycle and the second duty cycle do not overlap.

[0026] Optionally, the zero-voltage switching network discharges the first switch, the second switch, the fifth switch and the sixth switch in a time period between the first switch state and the second switch state, so as to achieve zero-voltage switching on the switches.

[0027] Optionally, the zero-voltage switching network comprises a fourth capacitor and a third inductor connected in series between the second node and the ground potential.

[0028] Optionally, the first switch to the eighth switch each comprise an N-type MOSFET, the first control signal is coupled to a gate terminal of the N-type MOSFET forming the first switch, the third switch, the sixth switch and the eighth switch, so as to turn on and off the N-type MOSFET, and the second control signal is coupled to a gate terminal of the N-type MOSFET forming the second switch, the fourth switch, the fifth switch and the seventh switch, so as to turn on and off the N-type MOSFET.

[0029] Optionally, during the first duty cycle, the inductor current of the first inductor increases and the inductor current of the second inductor decreases; during the second duty cycle, the inductor current of the first inductor decreases and the inductor current of the second inductor increases.

[0030] Optionally, the hybrid converter generates an output voltage on the output node that is stepped down by a value of M + (M / 2)*N1 / N2.

[0031] Optionally, the first duty cycle and the second duty cycle have substantially equal durations within each switching cycle.

[0032] With respect to the prior art, the technical solution of the present application has at least the following beneficial effects:

[0033] According to various aspects of the present application, the non-isolated DC-DC switching hybrid converter is implemented using a cross-coupled series capacitor four step-down buck converter that incorporates a zero voltage switching network for implementing soft switching and integrates a coupled inductor for implementing a fixed step-down ratio. The hybrid converter is capable of supporting high step-down ratios (e.g., 8: 1) while providing high efficiency.

[0034] In addition, the hybrid converter is capable of converting electrical energy in a bidirectional manner. That is, when the switching hybrid converter receives an input voltage on the input node, the converter provides a stepped down output voltage on the output node. However, when the switching hybrid converter receives an input voltage on the output node, the converter provides a stepped up output voltage on the input node.

[0035] In other embodiments, the DC-DC switching hybrid converter can be implemented by replacing the coupled inductor with a transformer. In this case, the turns ratio of the transformer can be used to implement a larger step-down ratio. BRIEF DESCRIPTION OF DRAWINGS

[0036] Various embodiments of the present application are disclosed in the following detailed description and in the drawings. While various examples of the present application are depicted and described, it will be appreciated that no limitation is placed on the application as described. It will be appreciated that the same reference designations can refer to the same structures throughout the drawings. It will also be appreciated that the drawings are not necessarily to scale.

[0037] Figure 1 A schematic diagram of the DC-DC switching hybrid converter described in one embodiment of the present application.

[0038] Figure 2 A diagram of the operation of the switching hybrid converter described in the present application and the changes in the signal waveforms within a switching cycle.

[0039] Figure 3(a) is Figure 1 the operation of the switching hybrid converter in the first switching state.

[0040] Fig. 3(b) is a schematic diagram of the operation of the non-isolated DC-DC hybrid converter in a second switching state. Figure 1 Fig. 3(b) is a schematic diagram of the operation of the non-isolated DC-DC hybrid converter in a second switching state.

[0041] Figure 4 Fig. 4 is a schematic diagram of a non-isolated DC-DC hybrid converter in another embodiment of the application.

[0042] Fig. 4 is a schematic diagram of a non-isolated DC-DC hybrid converter in another embodiment of the application.

[0043] 10: hybrid converter;

[0044] 12: node;

[0045] 14: node;

[0046] 16: node;

[0047] 18: node;

[0048] 20: node;

[0049] 22: node;

[0050] 24: node;

[0051] 26: node;

[0052] 28: output node;

[0053] 42: first group;

[0054] 43: first duty cycle;

[0055] 44: second group;

[0056] 45: second duty cycle;

[0057] 46: current profile in inductor LI;

[0058] 48: current profile in inductor L2;

[0059] 50: hybrid converter;

[0060] 61: node;

[0061] 62: node;

[0062] 63: first primary winding;

[0063] 64: second primary winding;

[0064] 65: first secondary winding;

[0065] 66: second secondary winding. DETAILED DESCRIPTION

[0066] According to various aspects of the present invention, a non-isolated DC-DC switching hybrid converter is implemented using a cross-coupled series capacitor quadruple step-down buck converter. This converter incorporates a zero-voltage switching network for soft switching and integrates a coupled inductor for achieving a fixed step-down ratio. This hybrid converter can support high step-down ratios (e.g., 8:1) while providing high efficiency.

[0067] Furthermore, the hybrid converter is capable of converting electrical energy in a bidirectional manner. That is, when the switching hybrid converter receives an input voltage at an input node, the converter provides a stepped-down output voltage at an output node. However, when the switching hybrid converter receives an input voltage at an output node, the converter provides a stepped-up output voltage at the input node.

[0068] In other embodiments, the DC-DC switching hybrid converter can be implemented by replacing the coupled inductor with a transformer. In this case, the turns ratio of the transformer can be used to achieve a larger step-down ratio.

[0069] In this specification, a hybrid converter refers to a converter topology that combines capacitive and inductive switching networks to reduce component stress, component size, and switching losses while maintaining or improving power processing efficiency.

[0070] Figure 1 Schematic diagram of a non-isolated DC-DC switching hybrid converter in an embodiment of the present invention. Figure 1 , the non-isolated DC-DC switching hybrid converter 10 consists of a switched capacitor converter circuit with three flying capacitors, a coupled inductor, and a zero voltage switching network. The hybrid converter 10 receives an input voltage Vin at an input node 12 and generates an output voltage Vout at an output node 28. The hybrid converter 10 implements a fixed M:1 step-down ratio, where M is an integer. In some embodiments, the fixed step-down ratio is 8:1, where the input voltage is 48V and the output voltage is 6V. The hybrid converter 10 of the present disclosure is particularly suitable for applications that require a large conversion ratio while providing high conversion efficiency. In other embodiments, the hybrid converter 10 of the present invention can be configured to provide other fixed step-down ratio values, such as 4:1 or 6:1, which is understood by those skilled in the art.

[0071] More specifically, the switched capacitor converter circuit includes eight switches S1 to S8. Switches S1 and S4 are connected in series between the input voltage Vin (node ​​12) and the ground potential (node ​​14). Switches S5 to S8 are connected in series between the ground potential. In other words, switches S5 to S8 are connected in series, with the terminal terminals of switches S5 and S8 both connected to the ground potential (node ​​14). In this embodiment, switches S1-S8 are implemented using N-type MOSFET devices or NMOS transistors. In other embodiments, other suitable devices may be used to implement the switches.

[0072] The switched capacitor converter circuit further comprises a first flying capacitor C fly between switches S2 and S3. Node 26 is between switches S7 and S8, which is also the switching voltage node Vsw2. Capacitor C2 is connected between node 24 and node 20. Node 24 is between switches S6 and S7. Node 20 is between switches S3 and S4, which is also the switching voltage node Vswl.

[0073] The hybrid converter 10 comprises a pair of inductors LI and L2 configured as a coupled inductor. As an explanation, a coupled inductor has two or more windings on a common magnetic core. In this specification, inductors LI and L2 represent two windings formed on the common magnetic core of the coupled inductor. Inductor LI is connected between node 20 and the output node 28. Inductor L2 is connected between node 26 and the output node 28. In the coupled inductor configuration, the voltages on inductors LI and L2 are forced to be the same. Therefore, the midpoint or common node 28 of inductors LI / L2 has half of the voltage on the coupled inductor LI / L2.

[0074] In this illustration, the output voltage Vout is provided to a load represented by a capacitor Cout and a resistor Rout in parallel. The capacitor Cout and the resistor Rout are only a representation of the load and are not intended to represent actual circuit elements. The output voltage Vout is stepped down from the input voltage Vin with a fixed step-down ratio of M: 1. That is, the output voltage Vout is 1 / M of the input voltage Vin. For example, the input voltage Vin can be 48V and the step-down ratio of the hybrid converter is 8: 1. Therefore, the output voltage Vout is 1 / 8 of the input voltage, which is 6V.

[0075] The hybrid converter 10 controls the switches S1-S8 in response to clock signals. For example, the hybrid converter 10 can employ pulse width modulation (PWM) to control the duty cycle of the switches S1-S8. That is, the on-time of the switches S1-S8 at a given fixed or variable frequency can be controlled by adjusting the pulse width. In embodiments of the present application, the hybrid converter 10 includes a PWM controller (not shown) that receives the clock signals and generates one or more control signals having a desired duty cycle to drive the switches S1-S8. For example, the clock signals have a given clock frequency, and each clock signal period defines a switching period in the hybrid converter.

[0076] In embodiments of the present application, the switches S1, S3, S6 and S8 (first group of switches) are controlled by a first control signal to synchronize the switches. Meanwhile, the switches S2, S4, S5, S7 (second group of switches) are controlled by a second control signal to synchronize the switches. In a switching period, the first control signal has a first duty cycle corresponding to a first switching state to turn on the switches S1, S3, S6 and S8; the second control signal has a second duty cycle corresponding to a second switching state to turn on the switches S2, S4, S5, S7. In this embodiment, the first duty cycle and the second duty cycle do not overlap. That is, the first group of switches (S1, S3, S6 and S8) and the second group of switches (S2, S4, S5, S7) alternate switching and do not turn on at the same time.

[0077] In embodiments of the present application, if the switches S1-S8 are MOSFET devices, the first and second control signals are coupled to the gate terminals of the respective MOSFET devices to turn on and off the MOSFET devices, respectively.

[0078] Since the inductors L1 and L2 are implemented as coupled inductors, the voltages across the inductors L1 and L2 are the same in the first switching state; the voltages across the inductors L1 and L2 are the same in the second switching state.

[0079] During operation of the hybrid converter 10, it is generally desirable to avoid "hard switching" in the switched capacitor converter circuit to reduce current spikes during the switching transition between the first and second duty cycles, preventing one group of switches from being turned off while the other group of switches is being turned on. In particular, "soft switching" is a better option, where the switches are switched when the voltage across them is close to zero and the current through the switches is close to zero. In embodiments of the present application, the hybrid converter 10 includes a zero voltage switching network to achieve soft switching capability. Referring to Figure 1The zero-voltage switching network in hybrid converter 10 is implemented by capacitor Czvs and inductor Lzvs connected in parallel between node 22 and ground potential. Specifically, a first terminal of capacitor Czvs is connected to node 22 (between switches S5 and S6), and a second terminal is connected to inductor Lzvs. A first terminal of inductor Lzvs is connected to capacitor Czvs, and a second terminal is connected to ground potential.

[0080] In operation, the zero-voltage switching network provides free current to discharge the voltage on switches S1, S2, S5, and S6 during the dead time between active duty cycles. For example, the zero-voltage switching network charges and discharges the drain-to-source voltage of the MOSFET devices of switches S1, S2, S5, S6 during the dead time or transition time between active duty cycles. In one example, switches S1 and S6 are turned on during an active duty cycle, and the ZVS network (i.e., zero-voltage switching network) provides current to discharge switches S2 and S5 and charge switches S1 and S6 during the dead time before the next active duty cycle. Then, switches S2 and S5 are turned on with zero-voltage switching in the next active duty cycle. In this way, zero-voltage crossover is achieved, where the next duty cycle starts with near zero current on switches S1, S2, S5, S6 and flying capacitor C fly When hybrid converter 10 achieves soft switching capability, the converter can have low switching losses and achieve higher efficiency and power density.

[0081] In embodiments of the invention, hybrid converter 10 includes inductors and capacitors connected in series, forming a resonant tank. Capacitors C1 and C2 resonate with the leakage inductance of the coupled inductors and the parasitic inductance in the printed circuit board implementing the DC-DC converter. Notably, switches S3, S4, S7, and S8 will have inherent soft switching functionality as long as the resonant tank and switching frequency are designed properly.

[0082] One notable feature of the hybrid converter of the present disclosure is that the converter is bidirectional. That is, the hybrid converter is capable of converting electrical energy in a bidirectional manner. In the above description, input voltage Vin is provided at input node 12, and output voltage Vout is obtained at output node 28. In other applications, the input voltage can be provided at output node 28, and the output voltage can be obtained at input node 12. In this case, the output voltage will be a 1:M step-up of the input voltage.

[0083] In the present embodiment, capacitors C1 and C2 have the same capacitance value, and inductors L1 and L2 have the same inductance value. In other embodiments, appropriate component values can be selected for capacitors C1, C2 and inductors L1, L2.

[0084] Figure 2including signal waveforms, describe operation of the switch hybrid converter over a switching period in some examples. In Figure 2 , Figure 1 Two switching periods during hybrid converter operation are illustrated in some examples. Referring to Figure 2 , a first control signal is applied to a first group 42 of switches (S1, S3, S6 and S8). These switches are therefore turned on during a first duty cycle 43, and otherwise off. At the same time, a second control signal is applied to a second group 44 of switches (S2, S4, S5 and S7). These switches are therefore turned on during a second duty cycle 45, and otherwise off. In one example, the first and second duty cycles 43, 45 are each less than 50% of the switching period. In this way, the first and second duty cycles 43, 45 do not overlap. That is, the first group 42 of switches is turned off for a dead time DT before the second group 44 of switches is turned on. In the next switching period, the second group 44 of switches is turned off for a dead time DT before the first group 42 of switches is turned on. In other words, during the dead time DT between the first and second duty cycles, both groups of switches are turned off. In one embodiment, the first duty cycle 43 and the second duty cycle 45 have substantially equal durations within each switching period.

[0085] In operation, during the first duty cycle, when the first group 42 of switches is turned on, the current I L1 in inductor LI oscillates and increases as the magnetization current increases, while the current I L2 in inductor L2 also oscillates but decreases as the magnetization current decreases. After the dead time, during the second duty cycle, when the second group 44 of switches is turned on, the current I L2 in inductor L2 oscillates and increases as the magnetization current increases, while the current I L1 in inductor LI also oscillates but decreases as the magnetization current decreases. During the dead time between the two duty cycles, when both groups of switches are turned off, the current through the capacitor Czvs and inductor Lzvs of the zero voltage switching network charges / discharges the residual voltage and current on the switches S1, S2, S5 and S6.

[0086] Figure 3(a) and 3(b) describe operation of the switch hybrid converter in first and second switching states in some examples. Referring first to Figure 3(a), in the first switching state, switches S1, S3, S6 and S8 are closed, while switches S2, S4, S5 and S7 are open. In this case, current flows from the input voltage Vin (node 12) through flying capacitor C flyand capacitor C2 and inductor LI to the output node 28. At the same time, another current flows from ground potential (node 14) to capacitor CI, which also flows to inductor LI and to the output node 28. Thus, the current in inductor LI increases in the first switching state. At the same time, one terminal of inductor L2 is connected to ground potential through the closed switch S8. The induced current flows through inductor L2 and the output node 28 to the load.

[0087] Referring first to Fig. 3(b), in the second switching state, switches S2, S4, S5, and S7 are closed, while switches SI, S3, S6, and S8 are open. In this case, current flows from ground potential through flying capacitor C fly and capacitor CI and inductor L2 to the output node 28. At the same time, another current flows from ground potential (node 14) to capacitor C2, which also flows to inductor L2 and to the output node 28. Thus, the current in inductor L2 increases in the second switching state. At the same time, one terminal of inductor LI is connected to ground potential through the closed switch S4. The induced current flows through inductor L2 and the output node 28 to the load.

[0088] Figure 4 is a schematic diagram of a non-isolated DC-DC switched hybrid converter in an alternative embodiment of the present invention. Figure 1 and Figure 4 The same elements in Figs. 1-4 use the same reference numbers, and the detailed description can omit to simplify the discussion. Reference is made to Figure 4 , a non-isolated DC-DC switched hybrid converter 50 is constructed in the same manner as the hybrid converter 10 in Figure 1 , except that a transformer is substituted for the coupled inductor. More specifically, the hybrid converter 50 includes a switched capacitor circuit including switches SI through S8 and three flying capacitors C fly , CI, and C2. The hybrid converter 50 also includes a zero voltage switching network capacitor Czvs and inductor Lzvs. The switched capacitor converter circuit in the hybrid converter 50 achieves a fixed M: 1 step-down ratio.

[0089] In embodiments of the present disclosure, the hybrid converter 50 includes a transformer Tl coupled between nodes 20 and 26 and coupled to the output node. The transformer Tl enables the converter to achieve a greater step-down ratio. In the present embodiment, the transformer Tl includes a first primary winding 63 and a second primary winding 64, both of which are inductively or magnetically coupled to a first secondary winding 65 and a second secondary winding 66. For example, the primary and secondary windings are wound on a common magnetic core.

[0090] In this embodiment, one terminal of the first primary winding 63 is connected to node 20 and the other terminal is connected to node 62, which is coupled to one terminal of capacitor C2. One terminal of the second primary winding 64 is connected to node 26 and the other terminal is connected to node 61, which is coupled to one terminal of capacitor C1. Nodes 61 and 62 represent the center taps of the first and second primary windings of transformer T1. In addition, in this embodiment, the first primary winding 63 of transformer T1 is connected in series with the first secondary winding 65 at node 20 between switches S3 and S4. The second primary winding 64 of transformer T1 is connected in series with the second secondary winding 66 at node 26 between switches S7 and S8. The first secondary winding 65 and the second secondary winding 66 are connected in series between nodes 20 and 26. The center tap of the first secondary winding 65 and the second secondary winding 66 is the output node 28, which provides the output voltage Vout. In this embodiment, the turns ratio of each primary winding and each secondary winding is N1 / N2. That is, the turns ratio of the first primary winding 63 and the first secondary winding 65 is N1 / N2; the turns ratio of the second primary winding 64 and the second secondary winding 66 is N1 / N2.

[0091] With this configuration, the hybrid converter 50 generates the output voltage Vout at the output node 28 with a step-down value determined by the fixed step-down ratio M:1 and the turns ratio N1 / N2 of transformer T1. Thus, the fixed step-down ratio of the hybrid converter 50 is increased by the turns ratio N1 / N2, where N1 is greater than N2. That is, the turns of the primary windings are greater than the turns of the secondary windings.

[0092] In one example, the step-down ratio of the hybrid converter 50 is expressed as:

[0093]

[0094] In the case of a fixed step-down ratio of 8:1, i.e., M=8, the step-down ratio of the hybrid converter 50 is given as:

[0095]

[0096] The hybrid converter 50 can operate in the same manner as the hybrid converter 10 described above, e.g., using a PWM controller (not shown) to generate control signals to alternately turn on and off switches S1-S8 to generate the output voltage Vout with the desired step-down ratio. In the hybrid converter 50, the step-down ratio is increased with the increase in the turns ratio of transformer T1.

[0097] In this detailed description, even if processing steps are not explicitly described in different embodiments, processing steps described for one embodiment can be used in different implementations. When reference is made herein to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously, unless the context indicates otherwise or unless otherwise specifically stated herein. Moreover, the method can also include one or more other steps performed before any defined step, between two defined steps, or after all defined steps, unless the context specifies otherwise or unless specifically indicated otherwise.

[0098] In this detailed description, the various embodiments or examples of the application can be implemented in a number of ways, including as a process; an apparatus; a system; and a composition of matter. There are provided above a detailed description of one or more embodiments of the application and the drawings illustrating the principles of the application. The application is described in connection with such embodiments, but the application is not limited to any embodiment. Numerous modifications and adaptations will be apparent to those skilled in the art. The scope of the application is limited only by the claims. The application includes a number of alternatives, modifications and equivalents. For a thorough understanding of the present application, numerous specific details are set forth in the description. These details are provided for purposes of example and are not intended to limit the application, except as described by the claims. For the purpose of clarity, technical material that is known in the technical fields related to the application has not been described in detail so that the present application is not unnecessarily obscured. The application is defined by the following claims.

Claims

1. A DC-DC switching hybrid converter, characterized in that, To receive an input voltage and generate an output voltage having a substantially constant amplitude on an output node, the hybrid converter comprises: a switched capacitor converter circuit comprising: a plurality of switches configured to provide a fixed M:1 step-down ratio between the input voltage and the output voltage; a first capacitor coupled between a first node and a second node, the first node being switchably coupled to the input voltage and the second node being switchably coupled to a ground potential; and a second capacitor and a third capacitor cross-coupled to be coupled to the plurality of switches; a first inductor and a second inductor, the first inductor and the second inductor having a first terminal coupled to the output node, the first inductor and the second inductor being configured to couple the inductors; and a zero voltage switching network coupled between the second node and the ground potential to discharge voltage on certain switches between switching states of the hybrid converter, wherein the hybrid converter generates the output voltage on the output node to be 1 / M of the input voltage.

2. The DC-DC switching hybrid converter of claim 1, wherein, The plurality of switches of the switched capacitor converter circuit comprises: a first switch, a second switch, a third switch, and a fourth switch connected in series between the input voltage and the ground potential, the first node being between the first switch and the second switch; and a fifth switch, a sixth switch, a seventh switch, and an eighth switch connected in series to each other, wherein terminal ends of the fifth switch and the eighth switch are connected to the ground potential, the second node being between the fifth switch and the sixth switch, wherein a first terminal of the second capacitor is coupled to a third node, the third node being between the second switch and the third switch, a second terminal of the second capacitor is coupled to a fourth node, the fourth node being between the seventh switch and the eighth switch; a first terminal of the third capacitor is coupled to a fifth node, the fifth node being between the sixth switch and the seventh switch, a second terminal of the third capacitor is coupled to a sixth node, the sixth node being between the third switch and the fourth switch; and wherein a first terminal of the first inductor is coupled to the output node, a second terminal of the first inductor is coupled to the sixth node; a first terminal of the second inductor is coupled to the output node, a second terminal of the second inductor is coupled to the fourth node.

3. The DC-DC switching hybrid converter of claim 2, wherein, The hybrid converter is controlled by clock signals having a first clock frequency, each clock signal period defining a switching period; and wherein the first switch, the third switch, the sixth switch, and the eighth switch are controlled by a first control signal, the second switch, the fourth switch, the fifth switch, and the seventh switch are controlled by a second control signal; within each switching period, the first control signal has a first duty cycle corresponding to a first switching state to turn on the first, third, sixth, and eighth switches, the second control signal has a second duty cycle corresponding to a second switching state to turn on the second, fourth, fifth, and seventh switches, the first duty cycle and the second duty cycle do not overlap.

4. The DC-DC switching hybrid converter of claim 3, wherein, The first duty cycle and the second duty cycle have substantially equal durations within each switching period.

5. The DC-DC switching hybrid converter of claim 3, wherein, The zero voltage switching network discharges the first switch, the second switch, the fifth switch, and the sixth switch within a time period between the first switching state and the second switching state to achieve zero voltage switching on the switches.

6. The DC-DC switching hybrid converter of claim 1, wherein, The zero-voltage switching network includes a fourth capacitor and a third inductor connected in series between the second node and the ground potential.

7. The DC-DC switching hybrid converter of claim 3, wherein, The first inductor and the second inductor have the same voltage value in the first switching state and the same voltage value in the second switching state.

8. The DC-DC switching hybrid converter of claim 3, wherein, The first to eighth switches each include an N-type MOSFET, a first control signal is coupled to gate terminals of the N-type MOSFETs forming the first, third, sixth and eighth switches so as to turn on and off the N-type MOSFETs, and a second control signal is coupled to gate terminals of the N-type MOSFETs forming the second, fourth, fifth and seventh switches so as to turn on and off the N-type MOSFETs.

9. The DC-DC switching hybrid converter of claim 8, wherein, During the first duty cycle, the inductive current of the first inductor increases and the inductive current of the second inductor decreases; during the second duty cycle, the inductive current of the first inductor decreases and the inductive current of the second inductor increases.

10. The DC-DC switching hybrid converter of claim 1, wherein, The second capacitor and the third capacitor have the same capacitance value, and the first inductor and the second inductor have the same inductance value.

11. The DC-DC switching hybrid converter of claim 1, wherein, The step-down converter has a fixed 8:1 step-down ratio.

12. A DC-DC switching hybrid converter, characterized in that, The hybrid converter receives an input voltage and generates an output voltage having a substantially constant amplitude at an output node, the hybrid converter comprising: a switched capacitor converter circuit including: a plurality of switches configured to provide a fixed M:1 step-down ratio between the input voltage and the output voltage; a first capacitor coupled between a first node and a second node, the first node being switchably coupled to the input voltage and the second node being switchably coupled to a ground potential; and the second capacitor and the third capacitor being cross-coupled to be coupled to the plurality of switches; a transformer including a first primary winding and a second primary winding inductively coupled to a first secondary winding and a second secondary winding, a center tap of the first primary winding and the second primary winding being coupled to the second capacitor and the third capacitor, respectively, a turns ratio of the first primary winding and the first secondary winding being N1 / N2; a turns ratio of the second primary winding and the second secondary winding being N1 / N2; and a zero-voltage switching network coupled between the second node and the ground potential to discharge voltage on certain switches between switching states of the hybrid converter, wherein the hybrid converter generates the output voltage at the output node having a step-down value determined by the fixed step-down ratio M:1 and the turns ratio N1 / N2 of the transformer.

13. The DC-DC switching hybrid converter of claim 12, wherein, The plurality of switches of the switched capacitor converter circuit includes: a first switch, a second switch, a third switch and a fourth switch connected in series between the input voltage and the ground potential, the first node being located between the first switch and the second switch; and a fifth switch, a sixth switch, a seventh switch and an eighth switch connected in series with each other, terminal terminals of the fifth switch and the eighth switch being connected to the ground potential, respectively, the second node being located between the fifth switch and the sixth switch, The first terminal of the second capacitor is coupled to a third node between the second switch and the third switch, and the second terminal of the second capacitor is coupled to a second center tap of the second primary winding; the first terminal of the third capacitor is coupled to a fifth node between the sixth switch and the seventh switch, and the second terminal of the third capacitor is coupled to a first center tap of the first primary winding; and The first primary winding of the transformer is connected in series with the first secondary winding at a sixth node between the third switch and the fourth switch; the second primary winding of the transformer is connected in series with the second secondary winding at a fourth node between the seventh switch and the eighth switch, and the first secondary winding and the second secondary winding are connected in series between the sixth node and the fourth node, and the center taps of the first secondary winding and the second secondary winding are the output node providing the output voltage.

14. The DC-DC switching hybrid converter of claim 13, wherein, The hybrid converter is controlled by clock signals having a first clock frequency, each clock signal period defining a switching period; and wherein the first switch, the third switch, the sixth switch and the eighth switch are controlled by a first control signal, and the second switch, the fourth switch, the fifth switch and the seventh switch are controlled by a second control signal; in each switching period, the first control signal has a first duty cycle corresponding to a first switch state to turn on the first switch, the third switch, the sixth switch and the eighth switch, and the second control signal has a second duty cycle corresponding to a second switch state to turn on the second switch, the fourth switch, the fifth switch and the seventh switch, and the first duty cycle and the second duty cycle do not overlap.

15. The DC-DC switching hybrid converter of claim 14, wherein, The zero-voltage switching network discharges the first switch, the second switch, the fifth switch and the sixth switch in a time period between the first switch state and the second switch state, so as to achieve zero-voltage switching on the switches.

16. The DC-DC switching hybrid converter of claim 12, wherein, The zero-voltage switching network comprises a fourth capacitor and a third inductor connected in series between the second node and the ground potential.

17. The DC-DC switching hybrid converter of claim 14, wherein, The first switch to the eighth switch each comprise an N-type MOSFET, the first control signal is coupled to the gate terminal of the N-type MOSFET forming the first switch, the third switch, the sixth switch and the eighth switch to turn on and off the N-type MOSFET, and the second control signal is coupled to the gate terminal of the N-type MOSFET forming the second switch, the fourth switch, the fifth switch and the seventh switch to turn on and off the N-type MOSFET.

18. The DC-DC switching hybrid converter of claim 17, wherein, During the first duty cycle, the inductive current of the first inductor increases and the inductive current of the second inductor decreases; during the second duty cycle, the inductive current of the first inductor decreases and the inductive current of the second inductor increases.

19. The DC-DC switching hybrid converter of claim 12, wherein, The hybrid converter generates the output voltage on the output node, and the output voltage has a step-down value of M+(M / 2)*N1 / N2.

20. The DC-DC switching hybrid converter of claim 14, wherein, The first duty cycle and the second duty cycle have substantially equal durations in each switching period.

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