Patent Description:
The present description relates generally to electronic circuits, and specifically to a half -bridge switching circuit system.

Half-bridge switching circuits can be implemented for a variety of applications to provide an output current/output voltage. As an example, motor drives can be implemented with half-bridge switching circuits. Many of the applications of motors in modern society implement variable speed drives to save energy, and all variable speed applications require an electronic drive to control the speed of the respective motor(s). Most variable-speed motor drives today use two-level converter architectures where each leg of the drive is a half -bridge switching circuit comprised of two switches. This configuration requires that each switch be rated for the full voltage of the application but minimizes the number of required parts and simplifies the design and control of the motor drive. Multi-level converters with three or more hard-switched voltage levels have also been developed for medium and high-power applications because they can generate higher quality output waveforms and achieve higher output voltages than the ratings of individual solid-state switching devices. The article "<NPL>) deals with a snubber circuit for a flying capacitor multilevel inverter and converter. The snubber circuit is an Undeland snubber which is formed by a resistor, an inductor, two capacitors, and two diodes. <CIT> discloses an inverter system including a three-phase inverter with a dual snubber circuitry. <CIT> discloses semiconductor light sources connected to a circuit board with a plurality of layers for dissipating waste heat from the semiconductor light sources.

A half-bridge switching circuit system in accordance with the invention is provided in appended independent claim <NUM>. Preferred embodiments of the invention are set forth in the appended dependent claims.

The present description relates generally to electronic circuits, and specifically to a half-bridge switching circuit system. As an example, the half-bridge switching circuit system can be implemented in a motor driver system to control a motor. For example, the motor driver system can be implemented to provide variable speed control of a motor, such as a three-phase motor. The motor driver system includes a motor controller that is configured to generate a plurality of switching signals, such as based on a desired speed of the associated motor. The half-bridge switching circuit can thus be configured to provide an output voltage to the motor to set the speed of the motor. The half-bridge switching circuit includes a plurality of switches, such as a first set of switches interconnecting a first voltage rail (e.g., a positive voltage rail) and the output and a second set of switches interconnecting a second voltage rail (e.g., a negative voltage rail) and the output. For example, the switches can be arranged as gallium nitride (GaN) switches that can be implemented for very high speed switching. The half-bridge switching circuit also includes a plurality of flying capacitors that interconnect the first and second sets of switches in a cascaded arrangement, such as to provide the output voltage as having a variable amplitude based on the complementary activation of the sets of switches.

The half-bridge switching circuit also includes a plurality of snubber circuits that are arranged in parallel with the switches of each of the first and second sets of switches and with the flying capacitors. The snubber circuits each include a series arrangement of a capacitor and a resistor, and can thus be configured to substantially mitigate the effects of unavoidable stray circuit inductance in series with the respective switches and flying capacitors. A peak voltage across the switches during voltage overshoot on switching transitions can increase as switching time decreases (e.g., because of the momentary voltage generated across the stray inductances in the circuit when the current transitions rapidly), but decreases with the addition of the snubber circuits which can partially absorb the energy stored in the stray inductances. Therefore, the snubber circuits can be configured to substantially reduce voltage overshoot and thus facilitate high speed switching of the switches of the switching circuit.

In addition, the half-bridge switching circuit system can be arranged to dissipate heat in an efficient manner. As an example, the half-bridge switching circuit can be arranged on a double-sided printed circuit board (PCB), such that the first set of switches can be coupled to a first surface of the double-sided PCB and the second set of switches can be coupled to a second surface of the double-sided PCB that is opposite the first surface. As a result, the half-bridge switching circuit can be arranged in a more compact arrangement of the PCB, and can dissipate heat in opposite directions with respect to the PCB. Additionally, the PCB can be arranged between two T-clad material arrangements that can be coupled to the PCB via one or more conductive material components on each surface of the PCB. Thus, the conductive material components can provide heat transfer from each surface of the PCB to the T-clad material arrangements, such that the T-clad material arrangements can radiate the heat from the PCB. Accordingly, the motor driver system can also provide sufficient heat dissipation of the associated circuitry.

<FIG> illustrates an example of a half-bridge switching system <NUM>. The half-bridge switching system <NUM> can be implemented in any of a variety of switching applications, such as motor control applications to control the speed and direction of a motor. In the example of <FIG>, the half-bridge switching system <NUM> includes is configured to generate an output voltage VDRV at an output <NUM> based on a DC rail voltage VDC. As an example, the rail voltage VDC can split with a center tap, and can thus include a positive portion and a negative portion relative to the center tap. As an example, the output voltage VDRV can be provided to a motor to control the speed and/or torque of the motor.

In the example of <FIG>, the half-bridge switching system <NUM> includes a set of switches <NUM> that are selectively activated via a set of switching signals SW to generate the output voltage VDRV based on the rail voltage VDC. As an example, the switching signals SW can be generated via a programmable controller (e.g., a motor controller). For example, the switches <NUM> can be configured as gallium nitride (GaN) MOSFET switches that can be implemented for very high speed switching (e.g., greater than <NUM>). Alternatively, the switches <NUM> can be configured as other types of switches, such as silicon (Si), silicon carbide, or other material-type switches. The switches <NUM> include a first set of switches interconnecting a positive portion of the rail voltage VDC and the output <NUM> and a second set of switches interconnecting a negative portion of the rail voltage VDC and the output <NUM>. In addition, the half-bridge switching system <NUM> includes a plurality of flying capacitors <NUM> that interconnect the sets of the switches <NUM> in a cascaded arrangement to provide the output voltage VDRV as having a variable amplitude based on the complementary activation of the sets of the switches <NUM>.

In addition, in the example of <FIG>, the half-bridge switching system <NUM> also includes snubber circuits <NUM>. The snubber circuits <NUM> are each configured as a series arrangement of a capacitor and a resistor, such that the snubber circuits <NUM> are arranged in parallel with the switches <NUM> and the flying capacitors <NUM>. The snubber circuits <NUM> can thus be configured to substantially reduce the voltage overshoot across the switches <NUM> on the switching transitions. As a result, the snubber circuits <NUM> can be implemented to substantially mitigate damage to the switches <NUM> during operation of the half-bridge switching system <NUM>. Additionally, by reducing the voltage overshoot across the switches <NUM>, the snubber circuits <NUM> can also facilitate more rapid switching speeds of the switches <NUM>, such as to implement the very high switching speeds of switches <NUM> that are configured as GaN MOSFET switches. Furthermore, the snubber circuits <NUM> in parallel with each of the flying capacitors <NUM> are likewise configured to mitigate an inductance associated with the flying capacitors <NUM> between the respective sets of the switches <NUM>.

<FIG> illustrates an example diagram <NUM> of a half-bridge switching system. The diagram <NUM> demonstrates a half-bridge switching circuit <NUM> that can correspond to the half-bridge switching system <NUM> in the example of <FIG>. Therefore, reference is to be made to the example of <FIG> in the following description of the example of <FIG>.

The half-bridge switching circuit <NUM> includes a cascaded arrangement of switch systems <NUM> and complementary switch systems <NUM>. The switch systems <NUM> are arranged between a positive rail voltage VDC+ (e.g., approximately <NUM> VDC) and an output <NUM> and the complementary switch systems <NUM> are arranged between a negative rail voltage VDC- (e.g., approximately -<NUM> VDC) and the output <NUM>. The switch systems <NUM> and the complementary switch systems <NUM> are thus arranged as complementary pairs having a quantity N stages, and are thus demonstrated as "SWITCH SYSTEM <NUM>" through "SWITCH SYSTEM N" and "SWITCH SYSTEM <NUM>'" through "SWITCH SYSTEM N'", respectively, where N is a positive integer. The Nth stage of the switch systems <NUM> is coupled to the positive rail voltage VDC+ and is separated from ground via a capacitor CDC+, and the Nth stage of the complementary switch systems <NUM> is coupled to the negative rail voltage VDC- and is separated from ground via a capacitor CDC-. The switch systems <NUM> are controlled via respective switching signals SW<NUM> through SWN (collectively "SW"), while the complementary switch systems <NUM> are controlled via respective switching signals SW<NUM>' through SWN' (collectively "SW'"), respectively.

The half-bridge switching circuit <NUM> also includes a plurality of flying capacitor systems <NUM> that interconnect the nodes between the switch systems <NUM> and the complementary switch systems <NUM>. Thus, the flying capacitor systems <NUM> are likewise arranged in a cascaded sequence, and are thus demonstrated as "FLYING CAP SYSTEM <NUM>" through "FLYING CAP SYSTEM N-<NUM>" in the example of <FIG>. The flying capacitor systems <NUM> can include one or more capacitors (in parallel and/or series arrangements) that behave as a capacitor. The voltage across FLYING CAP SYSTEM M is nominally controlled to have a value of M*(VDC+ - VDC-)/N, where M corresponds to a given one of the N-<NUM> flying capacitor systems <NUM>. For an example of a <NUM> volt DC bus and N = <NUM>, the voltage across FLYING CAP SYSTEM <NUM> is <NUM> V, such that the voltage across FLYING CAP SYSTEM <NUM> is <NUM> V, etc. The nominal voltage across any of the switch systems <NUM> is the voltage across two neighboring FLYING CAP SYSTEMs, which is <NUM> V in the previous example. The number N of stages can thus correspond to a desired quantization of the output voltage VDRV, with N+<NUM> discrete voltage levels available, namely VDC+, VDC-, and N-<NUM> evenly spaced voltage levels therebetween. For the example of a <NUM> volt DC bus and N=<NUM>, the <NUM> available hard-switched voltage levels are separated by approximately <NUM> volts. To which amplitude of the N+<NUM> voltage levels the output voltage VDRV is provided is based on the selective complementary activation of the switch systems <NUM> and the complementary switch systems <NUM> via the switching signals SW and SW'.

In the example of <FIG>, a given SWITCH SYSTEM M and a given SWITCH SYSTEM M' form a complementary pair controlled with mutually exclusive activation (e.g., with a controlled dead-time between deactivation of one and activation of the other). Accordingly, the current IDRV is provided at the output <NUM> to the motor (e.g., the motor <NUM>), with the selective activation of the switch systems <NUM> and the complementary switch systems <NUM> defining an amplitude of the associated output voltage VDRV. As an example, the selective complementary activation of the switch systems <NUM> and the complementary switch systems <NUM> can be such that a delay is provided between deactivation of one of the switch systems <NUM> and the complementary switch systems <NUM> and activation of the other of the switch systems <NUM> and the complementary switch systems <NUM> to substantially mitigate the occurrence of a shoot-through current.

In the example of <FIG>, the diagram <NUM> demonstrates an example of a switch system <NUM> that can correspond to one of the switch systems <NUM> and/or complementary switch systems <NUM>. As an example, all of the switch systems <NUM> and the complementary switch systems <NUM> can be arranged substantially identically, and can be configured substantially similar to the switch system <NUM>. The switch system <NUM> includes a metal-oxide semiconductor field-effect transistor (MOSFET) switch <NUM> and a snubber circuit <NUM> that is arranged in parallel with the MOSFET switch <NUM> between a first terminal <NUM> and a second terminal <NUM> (e.g., first and second nodes, respectively). As an example, the MOSFET switch <NUM> can be configured as a GaN MOSFET. The MOSFET switch <NUM> is controlled by a switching signal SWx that can correspond to any of the switching signals SW<NUM> through SWN or any of the switching signals SW<NUM>' through SWN'. The MOSFET switch <NUM> includes a body-diode <NUM> that may provide conduction of the current IDRV during deactivation of the complementary MOSFET, such as to provide a path for the current IDRV prior to the switch <NUM> being activated as a synchronous rectifier to reduce losses. The orientation of the MOSFET switch <NUM> when used as one of the switch systems <NUM> or <NUM> is such that when deactivated, the flying capacitor systems <NUM> cannot discharge. The snubber circuit <NUM> includes a series connection of a resistor RSNS and a capacitor CSNS between the first terminal <NUM> and the second terminal <NUM>. Although the switch system <NUM> is shown with a single MOSFET and single series RC snubber, alternative arrangements with a plurality of MOSFETs in parallel and snubber circuits in parallel is understood to be within the scope of the systems described herein.

In addition, the diagram <NUM> demonstrates an example of a flying capacitor system <NUM> that can correspond to one of the flying capacitor systems <NUM>. As an example, all of the flying capacitor systems <NUM> can be arranged substantially identically. The flying capacitor system <NUM> includes a flying capacitor CF and a snubber circuit <NUM> that is arranged in parallel with the flying capacitor CF between a first terminal <NUM> and a second terminal <NUM> (e.g., first and second nodes, respectively). Similar to as described previously regarding the snubber circuit <NUM>, the snubber circuit <NUM> includes a series connection of a resistor RSNF and a capacitor CSNF between the first terminal <NUM> and the second terminal <NUM>. Although the snubber circuit <NUM> is shown as a single series RC, alternative arrangements with many RC circuits in parallel is understood to be within the scope of the systems described herein.

The snubber circuits <NUM> and <NUM> can thus be configured to substantially mitigate the overvoltage across terminals <NUM> and <NUM> of the MOSFET switch <NUM> in the switch system <NUM> during switching transitions. As a result, the respective snubber circuits <NUM> and <NUM> can be implemented to substantially mitigate damage to the MOSFET switch <NUM> associated with each of the switch systems <NUM> and complementary switch systems <NUM> during operation of the motor driver system <NUM>. Additionally, the snubber circuits <NUM> and <NUM> can also facilitate more rapid switching speeds of the MOSFET switch <NUM> to implement very high switching of the switch systems <NUM> and the complementary switch systems <NUM>. Accordingly, the snubber circuits <NUM> and <NUM> can provide circuit protection and facilitate faster operation of the motor driver system <NUM>.

<FIG> illustrates another example of a motor system <NUM>. The motor system <NUM> can be implemented in any of a variety of motor control applications to control the speed and/or torque of a motor <NUM>. In the example of <FIG>, the motor <NUM> can be configured as a three-phase motor. The motor system <NUM> includes a motor driver system <NUM> that is configured to generate a first output voltage VDRV1 at a first output <NUM>, a second output voltage VDRV2 at a second output <NUM>, and a third output voltage VDRV3 at a third output <NUM>. Each of the outputs <NUM>, <NUM>, and <NUM> are coupled to the motor <NUM>, and thus the output voltages VDRV1, VDRV2, and VDRV3 each correspond to separate respective phases of the three-phase motor <NUM>. Accordingly, the output voltages VDRV1, VDRV2, and VDRV3 are provided to the motor <NUM> to control the speed and/or torque of the motor <NUM>. In the example of <FIG>, the motor driver system <NUM> can be configured to generate each of the output voltages VDRV1, VDRV2, and VDRV3 based on a differential voltage VDC, demonstrated as a positive rail voltage VDC+ and a negative rail voltage VDC-, similar to as demonstrated previously in the example of <FIG>.

In the example of <FIG>, the motor driver system <NUM> includes a motor controller <NUM> that is configured to generate a first set of switching signals SW1, a second set of switching signals SW2, and a third set of switching signals SW3. Additionally, the motor driver system <NUM> includes a first half-bridge switching circuit <NUM>, a second half-bridge switching circuit <NUM>, and a third half-bridge switching circuit <NUM>. The first half-bridge switching circuit <NUM> is configured to generate the first output voltage VDRV1 based on the first set of switching signals SW1, the second half-bridge switching circuit <NUM> is configured to generate the second output voltage VDRV2 based on the second set of switching signals SW2, and the third half-bridge switching circuit <NUM> is configured to generate the third output voltage VDRV3 based on the third set of switching signals SW3. Therefore, the motor controller <NUM> can control the output voltages VDRV1, VDRV2, and VDRV3 via the respective switching signals SW1, SW2, and SW3 and the respective half-bridge switching circuits <NUM>, <NUM>, and <NUM> to control the motor <NUM> (e.g., based on amplitude variations of the output voltages VDRV1, VDRV2, and VDRV3 at <NUM>° respective phase-delays).

Each of the half-bridge switching circuits <NUM>, <NUM>, and <NUM> can be configured substantially similar to the half-bridge switching circuit <NUM> in the example of <FIG>, and can thus include a set of switches and a complementary set of switches, as well as an associated set of flying capacitors. Thus, the set of switches and a complementary set of switches can be selectively activated in a complementary manner via the respective set of the switching signals SW1, SW2, and SW3 to generate the respective output voltages VDRV1, VDRV2, and VDRV3 based on the rail voltages VDC+ and VDC-. For example, the sets of switches and complementary switches can be configured as GaN MOSFETs.

In addition, in the example of <FIG>, each of the switching circuits <NUM>, <NUM>, and <NUM> also includes snubber circuits <NUM>. As an example, the snubber circuits <NUM> can each be configured substantially similar to the snubber circuits <NUM> and <NUM> in the example of <FIG>, and can thus be configured as a series arrangement of a capacitor and a resistor that is arranged in parallel with the switches, the complementary switches, and the flying capacitors. The snubber circuits <NUM> can thus be configured to substantially reduce the voltage overshoot at the terminals of the switches and the complementary switches during switching transitions. As a result, the snubber circuits <NUM> can be implemented to substantially mitigate damage to the switches and the complementary switches during operation of the motor driver system <NUM>. Additionally, by reducing the overvoltage at the terminals of the switches and the complementary switches the snubber circuits <NUM> can also facilitate more rapid switching speeds of the switches and the complementary switches.

While the example of <FIG> is described with respect to a three-phase motor control system, it is to be understood that the motor system <NUM> can be implemented in other motor control systems, and thus may implement any number of half-bridge switching systems. Additionally, while the description herein of the motor system <NUM> describes the manner of generating the output voltages VDRV to drive a motor, the principles and concepts described herein can apply equally when power is flowing in reverse, e.g., when the motor shaft is driven by another energy source, such as wind, water, or another energy source, as a generator, and the voltages VDRV is used to control the amount of power taken from the generator. Therefore, as described herein, the term "motor" is used to describe a motor that turns in response to the output voltage VDRV, but can also be used to describe a generator that is configured to generate electricity.

<FIG> illustrate example diagrams <NUM> and <NUM> of a portion of a circuit layout. The circuit layout of <FIG> can correspond to a top-view of a printed circuit board (PCB) <NUM> on which a half-bridge switching circuit is fabricated. <FIG> shows a cross-sectional view of a portion of the circuit in the example of <FIG> taken along the dashed line "A". As an example, the PCB <NUM> can be a four-layer, double-sided PCB on which the components of the half-bridge switching circuit are mounted and wired. As an example, the half-bridge switching circuit can correspond to the half-bridge switching circuit <NUM> in the example of <FIG> and/or one of the half-bridge switching circuits <NUM>, <NUM>, and <NUM> in the example of <FIG>.

The diagram <NUM> can correspond to a portion of the half-bridge switching circuit, such that additional parts of the half-bridge switching circuit can extend in any direction beyond the demonstrated boundaries of the PCB <NUM>. The diagram <NUM> demonstrates a plurality of MOSFET switches <NUM> and a plurality of capacitors <NUM> and a plurality of resistors <NUM> that correspond to respective snubber circuits across the MOSFET switches <NUM>. In the example of <FIG>, the capacitors <NUM> and the resistors <NUM> are interleaved with respect to each other (not all have reference numbers for clarity of illustration). As an example, each of the MOSFET switches <NUM> can include multiple interleaved drain and source terminals, such that an associated snubber circuit (e.g., the snubber circuit <NUM> in the example of <FIG>) can include a plurality of series connections of the capacitors <NUM> and the resistors <NUM> that are all arranged in parallel with a respective one of the MOSFET switches <NUM>.

The cross-sectional view in the diagram <NUM> in the example of <FIG> demonstrates that the other side of the double-sided PCB <NUM> can be arranged similar, with similar components, including complementary MOSFET switches <NUM>. The diagrams <NUM> and <NUM> also demonstrate a plurality of capacitors <NUM> (<NUM>) and a plurality of resistors <NUM> (<NUM>) that correspond to respective snubber circuits across the terminals of the flying capacitors. The flying capacitors are not shown in the example of <FIG>, but the terminals of each of the flying capacitors are routed on adjacent conductive layers of the double-sided PCB <NUM>. One example of a four-layer arrangement of the double-sided PCB <NUM> can be such that the terminals of each of the flying capacitor systems are routed on the inner two layers of the double-sided PCB <NUM>. For example, a given one of the flying capacitors can be conductively coupled to one of the MOSFET switches <NUM> and a respective one of the MOSFET switches <NUM> via a first conductive layer and a second conductive layer that is adjacent to the first conductive layer, respectively, of the double-sided PCB <NUM>. In addition, the capacitance of each of the flying capacitor systems may be divided such that one half of the capacitance can be connected to one edge of the double-sided PCB <NUM> and the other half of the capacitance can be connected to the other edge of the double-sided PCB <NUM>. The capacitor current is then split, with one half of the capacitor current being provided to one edge of the double-sided PCB <NUM> and the other half of the capacitor current being provided to the other edge of the double-sided PCB <NUM>. Such an arrangement reduces the total stray inductance in series with each of the flying capacitor systems. In the example of <FIG>, while the snubber circuit associated with each of the flying capacitors includes a single capacitor <NUM> and a single resistor <NUM>, it is to be understood that the corresponding snubber circuit (e.g., the snubber circuit <NUM> in the example of <FIG>) can include multiple series connections of the capacitors <NUM> and the resistors <NUM> that are all arranged in parallel with a respective one of the flying capacitors.

The diagrams <NUM> and <NUM> also demonstrate a set of thermally-conductive components <NUM> that extend along the surface of the PCB <NUM>. As an example, the thermally-conductive components <NUM> can be formed from copper, aluminum, or a variety of other materials that are highly conductive of heat. The thermally-conductive components <NUM> may also take on shapes other than the straight bars shown in diagrams <NUM> and <NUM>. As described in greater detail herein, the associated half-bridge switching system can be formed such that a T-clad material can be coupled to the thermally-conductive components <NUM> to provide efficient heat dissipation of the half-bridge switching circuit that is mounted to the PCB <NUM>.

As described previously, the PCB <NUM> can be formed as a four-layer double-sided PCB, and can thus include circuit components coupled to an underside of the double-sided PCB <NUM> relative to the top-view of the double-sided PCB <NUM> in the example of <FIG>. As an example, the MOSFET switches <NUM> can correspond to the switch systems <NUM> in the half-bridge switching circuit <NUM> while the MOSFET switches <NUM> can correspond to the complementary switch systems <NUM> of the half-bridge switching circuit <NUM> which can be mounted to an opposite surface of the double-sided PCB <NUM> in a manner similar to the MOSFET switches <NUM>. Snubber circuits can be placed adjacent to MOSFET switches <NUM> in a manner similar to how snubber circuits formed by the capacitors <NUM> and the resistors <NUM> are placed adjacent to MOSFET switches <NUM>. As another example, the double-sided PCB <NUM> can also include snubber circuits formed by the capacitors <NUM> and the resistors <NUM> for one flying capacitor and by capacitors <NUM> and resistors <NUM> for another flying capacitor. Furthermore, the double-sided PCB <NUM> can also include one or more thermally-conductive components <NUM> mounted on the opposite surface. Therefore, the double-sided PCB <NUM> can be arranged substantially similar to the arrangement demonstrated in the diagrams <NUM> and <NUM>.

Similar to the diagram <NUM>, the diagram <NUM> demonstrates the PCB <NUM> as a four-layer, double-sided PCB on which the components of the half-bridge switching circuit are mounted and wired. The diagram <NUM> demonstrates a MOSFET switch <NUM> and a plurality of capacitors <NUM> that correspond to a portion of the respective snubber circuit across the MOSFET switch <NUM> (e.g., along with the resistors <NUM> in the diagram <NUM> of the example of <FIG>). The diagram <NUM> also demonstrates a MOSFET switch <NUM> and a plurality of capacitors <NUM> that correspond to a portion of the respective snubber circuit across the MOSFET switch <NUM> on an opposite surface of the double-sided PCB <NUM> relative to the MOSFET switch <NUM> and the capacitors <NUM>. The MOSFET switch <NUM> and the capacitors <NUM> can correspond to one of the complementary switch systems of the associated half-bridge switching circuit (e.g., a complementary switch system <NUM> of the half-bridge switching circuit <NUM>).

The diagram <NUM> also demonstrates the set of thermally-conductive components <NUM> on the first surface of the double-sided PCB <NUM> and a set of thermally-conductive components <NUM> on the opposite surface of the double-sided PCB <NUM>. Each of the thermally-conductive bars <NUM> and <NUM> extend along the surface of the PCB <NUM>. In the example of <FIG>, a first T-clad material arrangement <NUM> is coupled to the thermally-conductive components <NUM> and a second T-clad material arrangement <NUM> is coupled to the thermally-conductive components <NUM>. Each of the T-clad material arrangements <NUM> and <NUM> can include a first conductive layer <NUM> (e.g., copper) that is coupled (e.g., soldered) to the respective thermally-conductive components <NUM> and <NUM> (e.g., along an entirety of the length of the respective thermally-conductive components <NUM> and <NUM>). Each of the T-clad material arrangements <NUM> and <NUM> also includes a thin electrically-insulating thermally-conductive layer <NUM> (e.g., ceramic) and a relatively thicker second conductive layer <NUM> (e.g., aluminum) that is coupled to the thin electrically-insulating thermally-conductive layer <NUM>.

Based on the arrangement of the T-clad material arrangements <NUM> and <NUM>, heat generated by the associated half-bridge switching circuit can be efficiently dissipated. Heat that is generated via the circuit components on the double-sided PCB <NUM> (e.g., the MOSFET switches <NUM> and <NUM>, the capacitors <NUM>, <NUM>, and <NUM>, the resistors <NUM> and <NUM>, etc.) can be conducted through metallic layers of PCB <NUM> and into the thermally-conductive components <NUM> and <NUM>. The heat can then be spread into the T-clad layer <NUM>, across the insulating layer <NUM> and into the thick heat-spreading layers <NUM>, as demonstrated diagrammatically in the example of <FIG> by the dashed lines <NUM>. In addition, as an example, the thick heat-spreading layers <NUM> can be held at a lower temperature by external means (e.g. air or liquid convection). Therefore, based on the mounting of the electronic components of the half-bridge switching circuit to both surfaces of the double-sided PCB <NUM>, and based on the coupling of the T-clad material arrangements <NUM> and <NUM> to the double-sided PCB <NUM> via the respective thermally-conductive components <NUM> and <NUM>, the heat that is generated by the electronic components of the half-bridge switching circuit can be efficiently dissipated.

It is to be understood that the arrangement of the circuit components with respect to the double-sided PCB <NUM> in the examples of <FIG> is provided by example only. It is to be understood that the components demonstrated in the diagrams <NUM> and <NUM> are not necessarily illustrated to scale, and are demonstrated merely to provide an exemplary relative layout of the associated components. Additionally, the layout of the circuit components in the diagrams <NUM> and <NUM> are provided as but one example. Furthermore, the use of a T-clad material arrangement to provide cooling for a circuit system is not limited to being implemented in half-bridge switching circuit depicted in the diagrams <NUM> and <NUM>, but can be implemented in combination with thermally-conductive components in any of a variety of surface-mount technology (SMT) circuit systems in which efficient cooling is desired, either on one or both sides of a PCB. Thus, it is to be understood that the arrangement of the circuit components in the diagrams <NUM> and <NUM> can be provided in any of a variety of ways on the double-sided PCB <NUM> (or a single-sided PCB) to provide substantially optimal space-savings and heat-dissipation, as described herein.

<FIG> illustrates yet another example of a motor system <NUM>. The motor system <NUM> can be implemented in any of a variety of motor control applications to control the speed and/or torque of a motor <NUM>. In the example of <FIG>, the motor <NUM> can be configured as a three-phase motor. The motor system <NUM> includes a motor driver system <NUM> that is configured to generate a first output voltage VDRV1, a second output voltage VDRV2, and a third output voltage VDRV3. Each of the output voltages VDRV1, VDRV2, and VDRV3 correspond to separate respective phases provided to control the three-phase motor <NUM>. Accordingly, the output voltages VDRV1, VDRV2, and VDRV3 are provided to the motor <NUM> to control the speed and/or torque of the motor <NUM>.

In the example of <FIG>, the motor driver system <NUM> includes a motor controller <NUM>, a boost rectifier/interactive inverter <NUM>, and a motor drive/boost rectifier <NUM>. Each of the boost rectifier/interactive inverter <NUM> and the motor drive/boost rectifier <NUM> includes three half-bridge switching circuits <NUM>, with each of the half-bridge switching circuits <NUM> corresponding to a separate phase of the three-phase power of the motor system <NUM>. When power is flowing from the three-phase power source <NUM> to the motor <NUM>, power stage <NUM> is controlled as a boost rectifier and power stage <NUM> is controlled as a variable-speed motor drive. When power is flowing from a generator <NUM> back to the three-phase power source <NUM>, power stage <NUM> is controlled as a boost rectifier and power stage <NUM> is controlled as a utility-interactive inverter. As an example, each of the half-bridge switching circuits <NUM> in power stages <NUM> and <NUM> can be arranged substantially similar to the half-bridge switching circuit <NUM> in the example of <FIG>, and can thus include snubber circuits in parallel with each MOSFET switch, each complementary MOSFET switch, and each flying capacitor. In the example of <FIG>, the boost rectifier/interactive inverter <NUM> receives a three-phase voltage, demonstrated as VPH1, VPH2, and VPH3, from a three-phase power source <NUM>, and is configured to generate a positive rail voltage VDC+ and a negative rail voltage VDC- from the three-phase voltage VPH1, VPH2, and VPH3 based on a set of switching signals SWII. Similar to as described previously in the example of <FIG>, the positive rail voltage VDC+ is separated from ground via a capacitor CDC+ and the negative rail voltage VDC- is separated from ground via a capacitor CDC-. As an example, the ground reference shown is an arbitrary choice that minimizes the voltage relative to ground for any phase of the motor or three-phase power source, but other ground references may be chosen. The motor drive/boost rectifier <NUM> is configured to generate each of the output voltages VDRV1, VDRV2, and VDRV3 based on the positive rail voltage VDC+ and the negative rail voltage VDC-, similar to as described previously in the example of <FIG>, in response to switching signals SWBR.

The motor controller <NUM> is configured to generate the switching signals SWII and SWBR that are provided to the boost rectifier/interactive inverter <NUM> and the motor drive/boost rectifier <NUM>, respectively. In addition, the motor controller <NUM> is demonstrated as receiving a plurality of feedback currents IFB1, IFB2, and IFB3 that can correspond, respectively, to the three-phases of the motor <NUM>. As an example, the feedback currents IFB1, IFB2, and IFB3 can be indicative of angle of rotation of the motor <NUM> (e.g., such as in encoder implementations or other applications that may require angular feedback of rotation of the motor <NUM>). The feedback currents IFB1, IFB2, and IFB3 can also correspond to the switching control scheme defined by the switching signals SWII and/or SWBR, such that the output voltages VDRV1, VDRV2, and VDRV3 can be generated based on information associated with the feedback currents IFB1, IFB2, and IFB3.

Furthermore, as another example, the motor controller <NUM> can be at least partially based on a single programmable device (e.g., a SoC FPGA) which contains at least one processor core surrounded by a large amount of programmable logic, that can be programmed with respect to the control scheme of the generation of the switching signals SWII and SWBR. In the example of <FIG>, the motor controller <NUM> receives a set of programming signals PRG that can be provided from a computer system, such as via a peripheral connection. For example, the programming signals PRG can be provided via a universal serial bus (USB), a serial port, or other external connection means. The program may be updated in the field based on the programming signals PRG. Therefore, the motor controller <NUM> can be programmable to provide the switching signals SWII and/or the switching signals SWBR in a predetermined control scheme for generating the rail voltages VDC+ and VDC- and/or the output voltages VDRV1, VDRV2, and VDRV3, such as based on the feedback currents IFB1, IFB2, and IFB3.

Accordingly, the motor driver system <NUM> can be implemented to include snubber circuits to substantially mitigate damage to the switches in the half-bridge switching circuits <NUM> during operation of the motor driver system <NUM>. Additionally, by reducing the voltage across the terminals of the switches in the half-bridge switching circuits <NUM>, the snubber circuits can also facilitate more rapid switching speeds of the switches, such as to implement the very high switching speeds, similar to as described previously. Furthermore, the half-bridge switching circuits <NUM> can each be mounted to a double-sided PCB, such as demonstrated in the diagrams <NUM> and <NUM> in the examples of <FIG>. The half-bridge switching circuits <NUM> can thus be arranged between T-clad material arrangements coupled to thermally-conductive bars on the double-side PCB, such as demonstrated in the diagrams <NUM> and <NUM> in the examples of <FIG>, to provide more efficient heat dissipation of the half-bridge switching circuits <NUM>.

Claim 1:
A half-bridge switching circuit system (<NUM>, <NUM>) comprising:
a first plurality of switches (<NUM>, <NUM>) connected between a first rail voltage and an output (<NUM>, <NUM>) on which an output voltage is provided;
a second plurality of switches (<NUM>, <NUM>) connected between a second rail voltage and the output (<NUM>, <NUM>), the first (<NUM>, <NUM>) and second (<NUM>, <NUM>) pluralities of switches being controlled via a plurality of switching signals;
a plurality of flying capacitors (<NUM>, <NUM>) connecting the first (<NUM>, <NUM>) and second (<NUM>, <NUM>) pluralities of switches; and
a plurality of snubber circuits (<NUM>, <NUM>), each of the plurality of flying capacitors (<NUM>, <NUM>) being connected in parallel with a respective one of the plurality of snubber circuits (<NUM>, <NUM>), each of the first plurality of switches (<NUM>, <NUM>) being connected in parallel with a respective one of the plurality of snubber circuits (<NUM>, <NUM>), and each of the second plurality of switches (<NUM>, <NUM>) being connected in parallel with a respective one of the plurality of snubber circuits (<NUM>, <NUM>), each of the plurality of snubber circuits (<NUM>, <NUM>) comprising a capacitor and a resistor connected in series with respect to each other.