Patent Application
20250203799
The present disclosure relates generally to power converters, and more particularly, to the packaging of power converters.
Electric utilities transmit unregulated alternating current (ac), which carries electrical signals across long distances and between buildings. This transmission requires a very high voltage that most circuits, e.g., electronic devices, within houses and businesses cannot handle. The voltage needs to be stepped down to be used in those settings. Similarly, high voltage batteries are used to power the motors of electric vehicles. The voltage output of the battery needs to be stepped down to power the interior accessories, e.g., windows, radio, and navigation system. Switched mode power converters, also referred to as switching power converters, are commonly used to provide a lower voltage to many of today's electronics due to their high efficiency, small size, and low weight. The switched mode power converter converts high voltage related to the unregulated ac input, to a lower voltage related to a constant or stable direct current (dc) output also known as a regulated dc output through an energy transfer element, e.g., a transformer. The switched mode power converter usually provides dc output regulation by sensing one or more signals representative of one or more output quantities, for example, voltage, current, or the combination of the two, and controlling the output in a closed loop. In operation, a switch is turned on and off to provide the desired output by varying the duty cycle, the switching frequency, or varying the number of pulses per unit time of the switch in a switched mode power converter.
Power converters generally include one or more controllers which sense the output of the power converter and control the operation of the switch to regulate the output. These controllers generally require a regulated or unregulated voltage source to power the circuit components of the controller.
Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Corresponding reference characters indicate corresponding components throughout the several views of the figures.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.
A conventional power converter includes an energy transfer element, e.g., a discrete transformer having an input winding and an output winding. The discrete transformer is typically mounted onto a printed circuit board. To minimize EMI and parasitic noise from resistance, inductance, and capacitance, the transformer and any other power converter circuit components are physically separated from each other.
The embodiments disclosed are directed towards a dc-dc power converter having the power circuit components mounted on a stack of circuit layers that includes a planar energy transfer element, e.g., a planar transformer. A hole extends through each of the circuit layers. A magnetic core assembly is positioned within the hole. A portion of the stack of circuit layers includes an input winding layer and an output winding layer. Each winding layer includes a winding and connections for electrical connectivity. The power converter circuit components include input and output circuit components that are mounted within an area of the stack and external to the magnetic core. The area of the stack encompasses the winding and connections for electrical connectivity of the larger of the input and output winding layers. In an embodiment, the input circuit components may be mounted on the stack of circuit layers and electrically connected to the input winding layer. In an embodiment, the output circuit components may be mounted on the stack of circuit layers and electrically connected to the output winding layer.
The stack of circuit layers 46 has a hole which extends through each of the circuit layers. The magnetic core assembly 48 and a portion of the stack of circuit layers 46 form a planar energy transfer element 38, e.g., a planar transformer. The portion of the stack of circuit layers 46 includes the input winding 38a and the output winding 38b. Each winding includes at least one winding layer. A winding layer includes a planar winding and connections for electrical connectivity. The planar winding may be a circular spiral or an oval spiral having one or more turns. The magnetic core assembly 48 is positioned within the hole substantially perpendicular to the stack of circuit layers 46. The area 38c of the planar energy transfer element 38 is coplanar with the first surface and encompasses the windings and connections for electrical connectivity of the input winding layers 38a and output winding layers 38b.
The controller 32, the input winding 38a, and the output winding 38b are electrically connected to the power converter circuit components. The controller 32 facilitates communication between the input and the output sides of the power converter.
The power converter circuit components are either input circuit components or output circuit components. In this embodiment, the power converter circuit components are mounted on the first surface 46a. A portion of the first surface 46a has been removed to show the layer that includes one layer of the input winding 38a. The input circuit components are mounted within the area 38c of the input and output windings 38a, 38b and external to the magnetic core assembly 48 and are electrically connected to the input winding 38a. The output circuit components are mounted within the area 38c of the input and output winding 38a, 38b and external to the magnetic core assembly 48 and are electrically connected to the output winding 38b. The input circuit components include a power switch 35. The output circuit components include a synchronous rectifier 34, a filter circuit 40, a sensing circuit 42, and a feedback circuit 44.
In one variation, all the power converter circuit components are mounted on the same surface of the stack and external to the magnetic core. The surface may be the first surface 46a or the second surface 46b.
In one variation, the input circuit components are mounted on one of the first surface 46a and the second surface 46b, and the output circuit components are mounted on the other of the first surface 46a and the second surface 46b.
In one variation, a first portion of the power converter circuit components are mounted on the first surface 46a and a second portion of the power converter circuit components are mounted on the second surface 46b.
The two-piece magnetic core assembly 48 may be an E-I core or an E-E core. For E-I core, the “I” is placed proximate to the open end of the “E” to form a 3-legged structure. For an E-E core, the corresponding legs of the “E” are placed proximate to each other. The “E”s have comparable height. One of skill in the art would understand that any magnetic core assembly may be positioned in the hole of the stack of circuit layers 46.
For a two-piece E-I or E-E shaped core, the magnetic core assembly 48 has a window. The planar energy transfer element 38 is surrounded by the magnetic core assembly 48 and positioned within the window. The central leg of the E portion extends through the hole of the stack of circuit layers 46.
In this simplified embodiment, the first surface 46a and the second surface 46b are connectivity layers. A connectivity layer may include copper traces used in the power converter to provide electrical connectivity within the stack 46.
For the input winding layer 38a and the output winding layer 38b, the winding may be a circular or an oval spiral and therefore may not necessarily run into the corners of the pcb layer. These corners may include connections for electrical connectivity, e.g., pads, vias, and traces, to allow electrical connectivity to the circuit layers. For each type of winding layer, e.g., input and output, there may be multiple layers of windings.
The area 38c of the planar energy transfer element is constrained by the circuit feature that occupies the most surface. The area 38c of the planar energy transfer element may include the windings and connections for electrical connectivity of the larger of the input and output windings 38a, 38b. The input and the output windings 38a, 38b may not occupy the same area because the number of turns (a turn is a revolution about the central hole), the pitch between the turns, or even the cross-sectional area of the conductors that make up the turns may be different. The power circuit components are positioned proximate to and overlapping any of the windings and the associated connections for electrical connectivity.
Each circuit layer may be a printed circuit board or a sublayer in the printed circuit board. Sublayers may include isolation and insulation layers to reduce electromagnetic interference (EMI) noise, to provide stress relief, or to provide electrical isolation between circuit components within the dc-dc converter.
Numerous specific details are set forth above in order to provide a thorough understanding of the present invention. It will be apparent, however, to one having ordinary skill in the art that the specific detail need not be employed to practice the present invention. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present invention. For example, skilled artisans will appreciate that elements in the previously described figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in the figures in order to facilitate a less obstructed view of these various embodiments of the present invention.
Reference throughout this specification to “one embodiment”, “an embodiment”, “one example” or “an example” means that a particular feature, structure or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, “one example” or “an example” in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures or characteristics may be combined in any suitable combinations and/or subcombinations in one or more embodiments or examples. Particular features, structures or characteristics may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality.
The description of illustrated examples of the present invention, including what is described in the Abstract, are not intended to be exhaustive or to be a limitation to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible without departing from the broader spirit and scope of the present invention. Indeed, it is appreciated that any specific example voltages, currents, frequencies, power range values, times, etc., are provided for explanation purposes and that other values may also be employed in other embodiments and examples in accordance with the teachings of the present invention.
Although the present invention is defined in the claims, the present invention can alternatively be defined in accordance with the following examples:
