System and method for powering vapor atomizer

Abstract

This invention describes a system comprising a converter configured to be electrically coupled to a power source and a heating element of an evaporator atomizer. The converter can be further configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter may be a DC-to-DC converter. A power monitor configured to be electrically coupled to the heating element measures a current through the heating element, measures a voltage across the heating element, calculates a power and / or resistance, and outputs a control signal to the converter. The converter can be configured to be controlled by the control signal to change the second voltage to maintain a target power or a target temperature above the heating element. This invention also describes related devices, systems, techniques, and objects.

Description

System and Method for Powering an Evaporator Atomizer The subject matter described herein relates to powering an evaporator atomizer using a direct current to direct current converter. Evaporator devices (which may also be referred to as evaporators, electronic vaporizer devices (electronic vaporizer device or e-vaporizer device)) can be used to deliver an aerosol containing one or more active ingredients (e.g., a gas phase and / or condensed phase material suspended in air or some other gas carrier of a stationary or moving mass) to a user of the device by inhalation of the aerosol. For example, electronic nicotine delivery systems (ENDS) include a class of evaporator devices powered by a battery pack and used to simulate the smoking experience without burning tobacco or other substances. Evaporators are becoming increasingly popular in prescription medical applications, drug delivery, and the consumption of tobacco, nicotine, and other plant-based materials. Evaporator devices can be portable, self-contained, and / or easy to use. When using an evaporator device, a user inhales an aerosol (commonly referred to as "vapor"), which can be generated by an evaporator (e.g., causing a liquid or solid to at least partially transform into a gas phase) of a heat generating element of an evaporable material, which can be a liquid, a solution, a solid, a paste, a wax, and / or any other form that can be used compatibly with a particular evaporator device. The evaporable material used with an evaporator can be provided in a cartridge, e.g., a separable part of an evaporator device that houses the evaporable material and includes an outlet (e.g., a mouthpiece) for inhalation of the aerosol by a user. In order to receive the inhalable aerosol generated by an evaporator device, in certain examples, a user can activate the evaporator device by suction, by pressing a button, and / or by some other method. As used herein, a suction refers to a manner in which a user inhales such that a certain volume of air is drawn into the evaporator device, causing a combination of the evaporated evaporable material and the volume of air to generate an inhalable aerosol. One method by which an evaporator device generates an inhalable aerosol from an evaporable material involves heating the evaporable material in an evaporator atomizer or evaporation chamber (e.g., a heater chamber) to cause the evaporable material to convert to the gas (gas or vapor) phase. An evaporator atomizer or evaporation chamber can refer to a region or volume within an evaporator device in which a heat source (e.g., a conduction, convection, and / or radiation heat source) causes heating of an evaporable material to produce a mixture of air and the evaporated material to form a vapor for inhalation by a user of the evaporator device. An evaporator atomizer can be used to evaporate a liquid into an aerosol and may require power and temperature control of a heating element, such as a resistive wire coil, to produce consistent vapor and prevent degradation of the liquid due to exposure to high temperatures. Generally, two heating-related parameters that can be controlled include the electrical power of the heating element and the temperature of the heating element. In a typical evaporator atomizer, the heater coil can be composed of a conductor having a positive temperature coefficient of resistance (TCR) such that its resistance increases as its overall temperature increases. The control loop measures the increase in resistance from ambient temperature to high temperature and adjusts the power to the heater to maintain a target operating temperature to obtain consistent vapor. Heater power control can be implemented using pulse width modulation (PWM), where the current to the heating element is rapidly turned on and off to control the electrical power dissipated as heat in the element. Although this PWM method can control a heating element, implementations may not tolerate large variations in the contact resistance of the heater and the pod, may require interruption of the power supply to measure the heater resistance, may result in shorter battery pack run times, may result in shorter run times at lower temperatures, may cause faster battery pack aging, may result in limited system integration, may result in limited TCR, and may result in increased component count and cost of measuring the heater resistance. In a particular aspect of the subject matter, challenges associated with powering an evaporator device can be addressed by including one or more features described herein or comparable / equivalent methods as would be understood by one of ordinary skill in the art. Aspects of the subject matter are directed to methods and systems for powering a heating element of an evaporator device. Details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the [Embodiments], [Brief Description of the Drawings], and [Claims]. The appended claims of the present invention are intended to define the scope of the protected subject matter. In some variations, one or more of the following features may be included in any feasible combination, as appropriate. In one aspect, a system includes a converter configured to be electrically coupled to a power source and a heating element of an evaporator atomizer. The converter may further be configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter can be a direct current to direct current converter. A power monitor can be configured to be electrically coupled to the heating element, measure a current through the heating element, measure a voltage across the heating element, calculate a power and / or resistance, and output a control signal to the converter. The converter can be configured to be controlled by the control signal to vary the second voltage to maintain a target power or a target temperature across the heating element. One or more of the following features may be included in any feasible combination. For example, the converter may include a boost and / or a buck converter. The converter may include an energy storage device. The energy storage device may include a capacitor in a switched capacitor topology or a charge pump topology. The energy storage device may include an inductor. The power monitor may include analog circuitry forming a closed loop control. The power monitor may include: an analog front-end circuit configured to measure the current through the heating element and the voltage across the heating element; and a digital converter including circuitry configured to provide the control signal based on the measured current through the heating element and the measured voltage across the heating element. The digital converter may be configured to provide the control signal as a pulse width modulation signal, a digital-to-analog conversion signal, or an inter-integrated circuit formatted signal. The power monitor may include a 4-wire connection for measuring the voltage across the heating element. The power monitor may alternatively include a 3-wire connection for measuring the voltage across the heating element. The power monitor may continuously measure the current and the voltage without interrupting the power to the heating element. A microcontroller and a switch may be included between the converter and the heating element. The switch may be electrically coupled to the microcontroller. The microcontroller may be configured to apply a pulse width modulation signal to a gate of the switch. The converter may be configured to operate at a first power level, and the microcontroller may be configured to determine a second power level based on the measured current through the heating element and the measured voltage across the heating element, and modify the pulse width modulation signal to control the switch to modify the second voltage. The converter may be configured to provide uninterrupted power to the heating element during a heating cycle. The power monitor may be configured to determine a change in a contact resistance of a contact between the converter and the heating element based on a change in the measured current. The system may further include a current source configured to be coupled to the heating element, the current source including a current source resistor and a current source switch. The system may further include a universal serial bus port, the universal serial bus port including a universal serial bus power rail, and the converter is configured to output a third voltage to the universal serial bus power rail. The system including the converter may also include a pulse width modulation (PWM) control circuit configured to be electrically coupled to the power source and the heating element of the evaporator nebulizer. The pulse width modulation control circuit is further configured to provide PWM power to the heating element. The power source may be a battery pack. In another aspect, an integrated converter includes a converter, a power monitor, and a charger in a single unit. The converter can be configured to be electrically coupled to a power source and a heating element of an evaporator atomizer. The converter can be further configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter is a direct current to direct current converter. The power monitor can be configured to be electrically coupled to the heating element, measure a current passing through the heating element, measure a voltage across the heating element, calculate a power and / or a resistance, and output a control signal to the converter. The charger can be configured to be electrically coupled to the power source to charge the power source. The converter can be configured to be controlled by the control signal to vary the second voltage to maintain a target power or a target temperature across the heating element. The converter and the charger can include a common inductor to supply power to the heating element and charge the power source. In another aspect, a method includes: measuring a current passing through a heating element of an evaporator atomizer; measuring a voltage across the heating element; calculating a power and / or a resistance; and controlling the operation of a converter to vary the second voltage to maintain a target power or a target temperature across the heating element. The current can be supplied by a converter configured to be electrically coupled to a power source and the heating element. The converter can be further configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter is a direct current to direct current converter. One or more of the following features can be included in any feasible combination. For example, the converter can include a boost and / or a buck converter; the converter can include an energy storage device. The energy storage device can include a capacitor in a switched capacitor topology or a charge pump topology. The energy storage device can include an inductor. A control signal can be provided to the converter as a pulse width modulation signal, a digital to analog conversion signal, or an inter-integrated circuit formatted signal. A pulse width modulation signal can be applied to a gate of a switch coupled between a microcontroller, the converter, and the heating element. The converter can be configured to operate at a first power level, and the microcontroller can be configured to determine a second power level based on the measured current passing through the heating element and the measured voltage across the heating element, and modify the pulse width modulation signal to control the switch to modify the second voltage. The converter can be configured to provide uninterrupted power to the heating element during a heating cycle. A change in a contact resistance of a contact between the converter and the heating element can be determined based on a variation of the measured current. A 4-wire connector can be used to measure the voltage above the heating element. Alternatively, a 3-wire connector can be used to measure the voltage above the heating element. The current passing through the heating element can be continuously measured without interrupting the power to the heating element. The voltage above the heating element can be continuously measured without interrupting the power to the heating element. The power source can be a battery pack. Details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the [Embodiments], [Brief Description of the Drawings], and [Claims]. Cross-reference This application claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 748,203, filed Oct. 19, 2018, entitled "Powering Vapor Atomizer", and claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 915,294, filed Oct. 15, 2019, entitled "Powering Vapor Atomizer", the entire contents of both of which are incorporated herein by reference. Embodiments of the subject matter include methods, devices, articles, and systems related to the vaporization of one or more materials for inhalation by a user. Example embodiments include methods of powering an evaporator device and systems including an evaporator device. As used herein and in the claims, the term "evaporator device" refers to any of a self - contained device, a device including two or more separable parts (e.g., an evaporator body including a battery pack and other hardware, and a cartridge containing an evaporable material), and / or the like. Evaporator devices (which may also be referred to as vaporizers, electronic vaporizer devices (electronic vaporizer device or e - vaporizer device)) can be used to deliver an aerosol containing one or more active ingredients (e.g., a gas - phase and / or condensed - phase material suspended in air or some other gas carrier of a stationary or moving mass) for inhalation by a user of the vaporizer device. As used herein, an "evaporator system" can include one or more components, such as an evaporator device. Examples of evaporator devices consistent with embodiments of the subject matter include electronic vaporizers, electronic nicotine delivery systems (ENDS), and / or the like. Generally, these evaporator devices are handheld devices that heat (such as by convection, conduction, radiation, and / or some combination thereof) an evaporable material to provide an inhalable dose of the material. The evaporable material used with an evaporator device can be provided within a cartridge (e.g., a part of an evaporator that houses the evaporative material in a reservoir or other container), which can be refillable or disposable when empty, such that a new cartridge containing the same or a different type of additional evaporable material can be used. An evaporator device can be a cartridge - using evaporator device, a cartridge - less evaporator device, or a multi - purpose evaporator device capable of being used with or without a cartridge. For example, an evaporator device can include: a heating chamber (e.g., an oven or other area where a heating element heats the material), configured to directly receive an evaporable material into the heating chamber; and / or a reservoir or the like for containing the evaporable material. In some embodiments, an evaporator device can be configured to work with a liquid evaporable material (e.g., a carrier solution in which one or more active and / or inactive ingredients are suspended or held in solution, or a liquid form of the evaporable material itself), a paste, a wax, and / or a solid evaporable material. A solid evaporable material can include a plant material (which dissipates a portion of the plant material as the evaporable material (e.g., a portion of the plant material remains as waste after the material is evaporated for inhalation by a user)), or can be, optionally, a solid form of the evaporable material itself such that all of the solid material can ultimately be evaporated for inhalation. A liquid evaporable material may also be capable of completely evaporating, or may include a portion of the liquid material that remains after all of the material suitable for inhalation has evaporated. Referring to the block diagram of FIG. 1A, an evaporator device 100 may include a power source 112 (e.g., a battery pack, which may be a rechargeable battery pack) and a controller 104 (e.g., a processor, circuitry, etc. capable of executing logic), the controller 104 being configured to control the delivery of heat to an atomizer 141 to cause a vaporizable material 102 to be converted from a condensed form (such as a solid, a liquid, a solution, a suspension, a portion of at least partially untreated plant material, etc.) to a gas phase. The controller 104 may be part of one or more printed circuit boards (PCBs) consistent with a particular embodiment of the subject matter. After the vaporizable material 102 is converted to the gas phase, at least a portion of the vaporizable material 102 in the gas phase may condense to form particulate matter that is at least partially in local equilibrium with the gas phase as part of an aerosol, which may form some or all of the inhalable dose provided by the evaporator device 100 during a user's draw or puff on the evaporator device 100. It should be understood that due to factors such as ambient temperature, relative humidity, chemical properties, flow conditions in the airflow path (both inside the evaporator and in the respiratory tract of a human or other animal), and / or mixing of the vaporizable material 102 in the gas phase or aerosol phase with other airflows, the interaction between the gas phase and the condensed phase in an aerosol generated by an evaporator device 100 may be complex and dynamic, which may affect one or more physical parameters of an aerosol. In some evaporator devices and particularly for evaporator devices configured to deliver volatile vaporizable materials, the inhalable dose may be predominantly present in the gas phase (e.g., formation of condensed phase particles may be very limited). The atomizer 141 in the evaporator device 100 may be configured to vaporize a vaporizable material 102. The vaporizable material 102 may be a liquid. Examples of the vaporizable material 102 include pure liquids, suspensions, solutions, mixtures, and / or the like. The atomizer 141 may include a wicking element (i.e., a wick), the wicking element being configured to deliver an amount of the vaporizable material 102 to a portion of the atomizer 141 that includes a heating element (not shown in FIG. 1A). For example, the wicking element may be configured to draw the vaporizable material 102 from a reservoir 140 configured to contain the vaporizable material 102 such that the vaporizable material 102 can be vaporized by heat delivered from a heating element. The wicking element may also optionally allow air to enter the reservoir 140 and replace the volume of the vaporizable material 102 that has been removed. In some embodiments of the subject matter, capillary action may draw the vaporizable material 102 into the wick for evaporation by the heating element, and air may return through the wick to the reservoir 140 to at least partially balance the pressure in the reservoir 140. Other methods of allowing air to return to the reservoir 140 to balance the pressure are also within the scope of the subject matter. As used herein, the term "wick" or "wicking element" includes any material capable of causing fluid movement via capillary pressure. The heating element may include one or more of a conductive heater, a radiative heater, and / or a convective heater. One type of heating element is a resistive heating element, which may include a material (such as a metal or alloy, e.g., a nichrome alloy or a non-metallic resistor) configured to dissipate electrical power in the form of heat when current is passed through one or more resistive segments of the heating element. In some embodiments of the present subject matter, the atomizer 141 may include a heating element that includes a resistive coil or other heating element that is wound around, positioned within, integrated into a monolithic shape of, pressed into thermal contact with, or otherwise configured to deliver heat to a wicking element to cause evaporation of the evaporable material 102 drawn from the reservoir 140 by the wicking element for subsequent inhalation by a user in a vapor phase and / or a condensed (e.g., aerosol particles or droplets) phase. Other wicking element, heating element, and / or atomizer assembly configurations are also possible. Additionally or alternatively, a particular evaporator device may be configured to produce an inhalable dose of the evaporable material 102 in a vapor phase and / or aerosol phase via heating of the evaporable material 102. The evaporable material 102 may be a solid phase material (such as a wax or the like) or a plant material (e.g., tobacco leaves and / or portions of tobacco leaves). In such evaporator devices, a resistive heating element may be part of the wall of an oven or other heating chamber in which the evaporable material 102 is placed, or otherwise incorporated into or in thermal contact with such walls. Alternatively, one or several resistive heating elements may be used to heat air passing through or over the evaporable material 102 to cause convective heating of the evaporable material 102. In still other examples, one or several resistive heating elements may be placed in close contact with the plant material such that direct conductive heating of the plant material occurs from within a mass of the plant material, as opposed to conduction only inward from the walls of an oven. The heating element can be activated in association with a user's draw (i.e., suck, inhale, etc.) on a mouthpiece 130 of an evaporator device 100 such that air flows from an air inlet along an airflow path through an atomizer 141 (i.e., a wicking element and a heating element). Optionally, the air can flow from the air inlet through one or more condensation regions or chambers to an air outlet in the mouthpiece 130. The incoming air moving along the airflow path moves over or through the atomizer 141, where the vaporizable material 102 in the gas phase is entrained into the air. The heating element can be activated via a controller 104, which can optionally be part of an evaporator body 110 as discussed herein, causing current to be delivered from a power source 112 through a circuit that includes a resistive heating element, which is optionally part of an evaporator cartridge 120 as discussed herein. As described herein, the entrained vaporizable material 102 in the gas phase can condense as it passes through the remainder of the airflow path such that an inhalable dose of the vaporizable material 102 in the form of an aerosol can be delivered from the air outlet (e.g., the mouthpiece 130) for a user to inhale. Activation of the heating element can be caused by automatically detecting a draw from one or more signals generated based on one or more of a sensor 113. The sensor 113 and the signals generated by the sensor 113 can include one or more of the following: one or more pressure sensors arranged to detect pressure along the airflow path relative to ambient pressure (or optionally measure a change in absolute pressure); one or more motion sensors (e.g., an accelerometer) of the evaporator device 100; one or more flow sensors of the evaporator device 100; a capacitive lip sensor of the evaporator device 100; detecting a user's interaction with the evaporator device 100 via one or more input devices 116 (e.g., buttons or other tactile control devices of the evaporator device 100); receiving a signal from a computing device communicating with the evaporator device 100; and / or via other methods for determining that a draw is occurring or about to occur. As discussed herein, an evaporator device 100 consistent with embodiments of the subject matter can be configured to connect (e.g., wirelessly or via a wired connection) to a computing device (or optionally two or more devices) that communicates with the evaporator device 100. To this end, the controller 104 can include communication hardware 105. The controller 104 can also include a memory 108. The communication hardware 105 can include firmware and / or can be controlled by software for implementing one or more encryption protocols for communication. An arithmetic device can be a component of an evaporator system that also includes an evaporator device 100, and can include its own hardware for communication, which can establish a wireless communication channel with the communication hardware 105 of the evaporator device 100. For example, an arithmetic device that is part of an evaporator system can include a general-purpose arithmetic device (such as a smartphone, a tablet computer, a personal computer, some other portable device (such as a smartwatch) or the like) that executes software to generate a user interface that enables a user to interact with the evaporator device 100. In other embodiments of the present subject matter, such a device that is part of an evaporator system can be a dedicated hardware piece, such as a remote control or other wireless or wired device with one or more physical or software (i.e., configurable on a screen or other display device and selectable via user interaction with a touch-sensitive screen or some other touch control device (such as a mouse, pointer, trackball, cursor button or the like)) interfaces. The evaporator device 100 can also include one or more outputs 117 or devices for providing information to the user. For example, the output 117 can include one or more light-emitting diodes (LEDs) configured to provide feedback to a user based on a state and / or operating mode of the evaporator device 100. In an example where an arithmetic device provides a signal related to the activation of a resistive heating element, or in other examples where an arithmetic device is coupled to the evaporator device 100 to implement various controls or other functions, the arithmetic device executes one or more computer instruction sets to provide a user interface and underlying data handling. In one example, detection by the arithmetic device of user interaction with one or more user interface elements can cause the arithmetic device to communicate with the evaporator device 100 to activate the heating element to reach an operating temperature for generating an inhalable dose of vapor / aerosol. Other functions of the evaporator device 100 can be controlled by interaction of a user with a user interface on an arithmetic device that communicates with the evaporator device 100. The temperature of a resistive heating element of the evaporator device 100 can depend on several factors, including an amount of electrical power delivered to the resistive heating element, conductive heat transfer to other parts of the electronic evaporator device 100 and / or to the environment, latent heat losses due to evaporation of the evaporable material 102 as a whole from the wicking element and / or atomizer 141, and convective heat losses due to an air flow (i.e., air that moves as a whole across the heating element or atomizer 141 when a user inhales on the evaporator device 100). As described herein, in order to reliably activate the heating element or heat the heating element to a desired temperature, in some embodiments of the present subject matter, the evaporator device 100 can utilize a signal from a sensor 113 (e.g., a pressure sensor) to determine when a user is inhaling. The sensor 113 can be positioned in the air flow path and / or can be connected (e.g., by a passage or other path) to an air flow path that includes: an inlet for allowing air to enter the evaporator device 100; and an outlet through which the user inhales the resulting vapor and / or aerosol, such that the sensor 113 experiences a change (e.g., a pressure change) as air is transmitted from the air inlet through the evaporator device 100 to the air outlet. In some embodiments of the present subject matter, the heating element can be activated in association with a user's draw, such as by automatically detecting the draw or by detecting a change (such as a pressure change) in the air flow path by the sensor 113. The sensor 113 can be positioned on the controller 104 (e.g., a printed circuit board assembly or other type of circuit board) or coupled to (i.e., electrically or electronically connected or connected via a wireless connection) the controller 104. To accurately make measurements and maintain the durability of the evaporator device 100, it may be beneficial to provide a seal 127 that is flexible enough to separate an airflow path from other parts of the evaporator device 100. The seal 127 (which can be a gasket) can be configured to at least partially surround the sensor 113 such that the connection of the sensor 113 to the internal circuitry of the evaporator device 100 is separated from a portion of the sensor 113 that is exposed to the airflow path. In an example of a cartridge-based evaporator, the seal 127 can also separate portions of one or more electrical connectors between the evaporator body 110 and the evaporator cartridge 120. These configurations of the seal 127 in the evaporator device 100 can help mitigate potential damaging effects on the evaporator components due to interaction with environmental factors such as water in the gas or liquid phase, other fluids (such as the evaporable material 102, etc.), and / or reduce the escape of air from the designated airflow path in the evaporator device 100. Unwanted air, liquid, or other fluids passing through and / or contacting the circuitry of the evaporator device 100 can cause various unwanted effects (such as altered pressure readings) and / or may cause unwanted materials (such as moisture, excessive evaporable material 102, etc.) to accumulate in parts of the evaporator device 100, where they may cause poor pressure signals, degradation of the sensor 113 or other components, and / or a shorter lifespan of the evaporator device 100. Leakage in the seal 127 can also cause a user to inhale air that has passed over parts of the evaporator device 100 that contain materials that may not be desired to be inhaled or are composed of such materials. In some embodiments, the evaporator body 110 includes a controller 104, a power source 112 (e.g., a battery pack), one or more of sensors 113, charging contacts (such as contacts for charging the power source 112), a seal 127, and a cartridge receptacle 118 configured to receive an evaporator cartridge 120 and couple with the evaporator body 110 through one or more of various attachment structures. In some examples, the evaporator cartridge 120 includes a reservoir 140 for containing the evaporable material 102, and the mouthpiece 130 has an aerosol outlet for delivering an inhalable dose to a user. The evaporator cartridge 120 may include an atomizer 141 having a wicking element and a heating element. Alternatively, one or both of the wicking element and the heating element may be part of the evaporator body 110. In embodiments where any part of the atomizer 141 (i.e., the heating element and / or the wicking element) is part of the evaporator body 110, the evaporator device 100 may be configured to supply the evaporable material 102 from the reservoir 140 in the evaporator cartridge 120 to the (one or more) parts of the atomizer 141 included in the evaporator body 110. A cartridge-based configuration of the evaporator device 100 that produces an inhalable dose of the evaporable material 102 (which is not a liquid) via heating of a non-liquid material is also within the scope of the subject matter. For example, the evaporator cartridge 120 may include a mass of plant material that has been processed and formed to be in direct contact with a portion of one or more resistive heating elements, and the evaporator cartridge 120 may be configured to mechanically and / or electrically couple to an evaporator body 110 that includes a controller 104, a power source 112, and one or more receptacle contacts 125a and 125b configured to connect to one or more corresponding cartridge contacts 124a and 124b and complete an electrical circuit with the one or more resistive heating elements. In one embodiment of the evaporator device 100, where the power source 112 is part of the evaporator body 110 and a heating element is disposed in the evaporator cartridge 120 and configured to couple with the evaporator body 110, the evaporator device 100 may include electrical connection features (e.g., components for completing an electrical circuit) for completing an electrical circuit that includes a controller 104 (e.g., a printed circuit board, a microcontroller, or the like), a power source 112, and a heating element (e.g., a heating element within the atomizer 141). These features may include: one or more contacts (referred to herein as cartridge contacts 124a and 124b) on a bottom surface of the evaporator cartridge 120; and at least two contacts (referred to herein as receptacle contacts 125a and 125b) disposed near a base of the cartridge receptacle 118 of the evaporator device 100 such that when the evaporator cartridge 120 is inserted into and coupled with the cartridge receptacle 118, the cartridge contacts 124a and 124b and the receptacle contacts 125a and 125b establish an electrical connection. The electrical circuit completed by these electrical connections may allow current to be delivered to a heating element and may further be used for additional functions, such as measuring the resistance of a heating element to determine and / or control the temperature of a heating element based on the thermal resistance coefficient of the heating element. In some embodiments of the subject matter, the cartridge contacts 124a and 124b and the receptacle contacts 125a and 125b may be configured to electrically connect in either of at least two orientations. In other words, by inserting the evaporator cartridge 120 into the cartridge receptacle 118 in a first rotational orientation (about an axis along which the evaporator cartridge 120 is inserted into the cartridge receptacle 118 of the evaporator body 110) such that the cartridge contact 124a is electrically connected to the receptacle contact 125a and the cartridge contact 124b is electrically connected to the receptacle contact 125b, one or more electrical circuits necessary for the operation of the evaporator device 100 may be completed. Additionally, by inserting the evaporator cartridge 120 into the cartridge receptacle 118 in a second rotational orientation such that the cartridge contact 124a is electrically connected to the receptacle contact 125b and the cartridge contact 124b is electrically connected to the receptacle contact 125a, one or more electrical circuits necessary for the operation of the evaporator device 100 may be completed. In one example of an attachment structure for coupling an evaporator cartridge 120 to an evaporator body 110, the evaporator body 110 includes one or more detents (e.g., pits, protrusions, etc.) that project inwardly from an inner surface of the cartridge receptacle 118, additional material (such as metal, plastic, etc.) formed to include a portion that projects into the cartridge receptacle 118, and / or the like. One or more outer surfaces of the evaporator cartridge 120 may include corresponding notches (not shown in FIG. 1A) that may fit over and / or otherwise snap onto such detents or protrusions when the evaporator cartridge 120 is inserted into the cartridge receptacle 118 on the evaporator body 110. When the evaporator cartridge 120 and the evaporator body 110 are coupled (e.g., by inserting the evaporator cartridge 120 into the cartridge receptacle 118 of the evaporator body 110), the detents or protrusions of the evaporator body 110 may fit over and / or otherwise be retained within the notches of the evaporator cartridge 120 to hold the evaporator cartridge 120 in place when assembled. This assembly can provide sufficient support to hold the evaporator cartridge 120 in place to ensure good contact between the cartridge contacts 124a and 124b and the receptacle contacts 125a and 125b, while allowing the evaporator cartridge 120 to be released from the evaporator body 110 when a user pulls on the evaporator cartridge 120 with a reasonable force to disengage the evaporator cartridge 120 from the cartridge receptacle 118. In some embodiments, at least one insertable end 122 of the evaporator cartridge 120 or the evaporator cartridge 120 configured to be inserted into the cartridge receptacle 118 may have a non-circular cross-section transverse to the axis along which the evaporator cartridge 120 is inserted into the cartridge receptacle 118. For example, the non-circular cross-section may be approximately rectangular, approximately elliptical (i.e., having an approximately elliptical shape), non-rectangular but having two sets of parallel or approximately parallel opposite sides (i.e., having a shape similar to a parallelogram), or other shapes having at least second-order rotational symmetry. In this context, an approximate shape indicates that a basic similarity to the described shape is evident, but the sides of the shape under discussion need not be perfectly linear and the vertices need not be perfectly sharp. Rounding of either or both of the edges or vertices of the cross-sectional shape is contemplated in any description of a non-circular cross-section herein. The cartridge contacts 124a and 124b and the receptacle contacts 125a and 125b may take various forms. For example, one or both sets of contacts may include conductive pins, tabs, posts, receiving holes for pins or posts, or the like. Some types of contacts may include springs or other features to facilitate better physical and electrical contact between the contacts on the evaporator cartridge 120 and the evaporator body 110. The electrical contacts may be gold-plated, as appropriate, and / or include other materials. Figure 1B illustrates an embodiment of the evaporator body 110 and the cartridge receptacle 118. The evaporator cartridge 120 can be releasably inserted into the cartridge receptacle 118. Figure 1B shows a top view of the evaporator device 100, which depicts the evaporator cartridge 120 positioned for insertion into the evaporator body 110. When a user draws on the evaporator device 100, air can be transferred between an outer surface of the evaporator cartridge 120 and an inner surface of the cartridge receptacle 118 on the evaporator body 110. Subsequently, the air can be drawn into the insertable end 122 of the cartridge through an evaporation chamber that includes or contains a heating element and a wick, and the air is drawn out through an outlet of the mouthpiece 130 to deliver an inhalable aerosol to a user. The reservoir 140 of the evaporator cartridge 120 can be formed in whole or in part from a translucent material such that a liquid level of the evaporable material 102 can be visible within the evaporator cartridge 120. The mouthpiece 130 can be a separable component of the evaporator cartridge 120 or can be integrally formed with one or more other components of the evaporator cartridge 120 (e.g., formed as a single structure with the reservoir 140 and / or the like). The discussion above regarding the electrical connection between the evaporator cartridge 120 and the evaporator body 110 being reversible such that at least two rotational orientations of the evaporator cartridge 120 within the cartridge receptacle 118 are possible. Further, in some embodiments of the evaporator device 100, the shape of the evaporator cartridge 120, or at least one shape of the insertable end 122 of the evaporator cartridge 120 configured to be inserted into the cartridge receptacle 118, can have at least two-fold rotational symmetry. In other words, the evaporator cartridge 120 or at least the insertable end 122 of the evaporator cartridge 120 can be symmetric when rotated 180° about an axis along which the evaporator cartridge 120 is inserted into the cartridge receptacle 118. In this configuration, the circuitry of the evaporator device 100 can support the same operation regardless of which symmetric orientation the evaporator cartridge 120 assumes. Figures 1C through 1D illustrate example features that can be included in an embodiment of the evaporator device 100 consistent with the implementations of the subject matter. Figures 1C and 1D show top views of an example of the evaporator device 100 before (Figure 1C) and after (Figure 1D) connecting the evaporator cartridge 120 to the evaporator body 110. Figure 1E illustrates a perspective view of one variation of the evaporator cartridge 120 holding the evaporable material 102. Any suitable evaporable material 102 can be accommodated within the evaporator cartridge 120 (e.g., within the reservoir 140), including solutions of nicotine or other organic materials. Figure 1F shows a perspective view of another example of an evaporator device 100 including an evaporator body 110 coupled to a separable evaporator cartridge 120. As depicted, the evaporator device 100 may include one or more outputs 117 (e.g., LEDs) configured to provide information to a user based on a state, operating mode, and / or the like of the evaporator device 100. In some aspects, the one or more outputs 117 may include a plurality of LEDs (i.e., two, three, four, five, or six LEDs). The one or more outputs 117 (i.e., each individual LED) may be configured to display light in one or more colors (e.g., white, red, blue, green, yellow, etc.). The one or more outputs 117 may be configured to display different light patterns (e.g., by illuminating a particular LED, changing the light intensity of one or more LEDs over time, illuminating one or more LEDs in a different color, and / or the like) to indicate different states, operating modes, and / or the like of the evaporator device 100. In some embodiments, the one or more outputs 117 may be near and / or at least partially disposed within a bottom region 160 of the evaporator device 100. Additionally or alternatively, the evaporator device 100 may include externally accessible charging contacts 128 that may be near and / or at least partially disposed within the bottom region 160 of the evaporator device 100. Figure 1G is a system block diagram showing an example of a conventional PWM heater control 160. The heater control includes a battery charger 162, a microcontroller 164, a PWM metal-oxide-semiconductor field-effect transistor (MOSFET) 165, a voltage measurement point (VMEAS) analog front end (AFE) 185, a low-dropout regulator (LDO) 174, and a current source 182. The PWM heater control 160 may include contacts 181 for coupling to a chamber 180 containing a heating element 185 and an evaporable material. The PWM heater control 160 may also be coupled to a battery pack 172. The microcontroller 164 may control the PWM MOSFET 165 to switch the current source 182 or the battery pack 172 in series with the heating element 185 to provide power to the heating element 185 for heating. In a conventional PWM control, electrical power is directly supplied from the battery pack 172 and conducted and interrupted by a solid-state switch (such as the PWM MOSFET 165). The heater resistance can be measured between PWM pulses by passing a known constant current through the heater and measuring the voltage drop across the heating element 185. In some existing evaporator atomizers, heater control is achieved by pulse-width modulation of the power supply (such as the battery pack) delivered to the heating element. As further explained below, a conventional PWM method can control a heating element. However, PWM control may not tolerate large variations in heater and chamber contact resistance, may require power interruption to measure the heater resistance, may result in shorter battery pack runtime, may result in shorter runtime at lower temperatures, may cause faster battery pack aging, may result in limited system integration, may result in limited TCR, and / or may result in increased component count and cost of measuring the heater resistance. Some PWM implementations may not tolerate large variations in heater and chamber contact resistance. PWM control may be limited to a maximum duty cycle. At low battery pack voltages, PWM control may not be able to compensate for an increase in chamber contact resistance to maintain the target power. PWM control may require a more stringent heater resistance tolerance in production to ensure that the target power in the heater can be achieved at low voltages. PWM control may reduce usability, i.e., the user may need to clean the chamber contacts frequently. PWM control interrupts the power supply to measure the temperature of the heating element. Due to PWM switching, it may be difficult to directly measure the power above the heater. For the same reason, it may be difficult to measure the heater resistance between PWM pulses, so the power supply to the heater is usually interrupted for measurement. PWM control may require a more complex circuit (such as a stable constant current source and a Wheatstone bridge) to measure the resistance. PWM control may result in shorter evaporator battery pack runtime. There is a minimum battery pack voltage limit to achieve the target power. For the above example, an 8.0 W target power requires a minimum of approximately 3.4 V under load. Below a load voltage of approximately 3.4 V, the PWM duty cycle is 100% and the system cannot deliver the target power. This will have a negative impact on the user experience at low charge states. For an aging battery pack, the minimum voltage limit is reached at an even higher charge state, resulting in shorter runtime. PWM control may result in shorter evaporator runtime at low temperatures. The battery pack impedance (DCIR) increases at low temperatures, even around 15ºC. This causes the battery pack voltage to drop suddenly under load and will result in a lower user experience and shorter operation time. At low temperatures below 10ºC, this effect is greater, resulting in a much shorter runtime. PWM control may lead to faster battery pack aging. Due to the relatively low heater resistance, the current in the PWM pulses is high at average and high battery pack voltages. This results in higher polarization, higher stress, faster aging, and shorter cycle life in the battery. PWM control may lead to limited system integration. The PWM control for charging and heater power control are separate circuits and require a larger board area. PWM control may require a relatively low resistance for the heating element, thus limiting design choices. PWM control may lead to limited heater TCR selection options. A higher TCR provides a greater resistance change with temperature, a greater signal, and thus better temperature measurement accuracy. However, a PWM control may require a low TCR to maintain heater power at low battery pack voltages. PWM control may lead to an increased component count and increased cost for measuring heater resistance. For example, the component count can be increased for an additional current source and a Wheatstone bridge circuit. The subject matter described herein provides many technical advantages over conventional PWM control and other heating element control techniques. For example, the subject matter can achieve improved system integration. In some embodiments, the charger and heater power control can be built into a single DC-DC converter. A single inductor can be used for charging and to power the heater. The combination of the charger and heater control circuits can provide a cost reduction and / or a space reduction. In some embodiments, the subject matter can achieve a reduction in board area, which can allow for a larger battery pack capacity or a smaller overall evaporator device. Lower total costs, tolerance to significant variations in heater and cabin contact resistance, and the like can be achieved. The output voltage can be adjusted proportionally with an increase in load resistance to maintain power. This can compensate for large variations in cabin contact resistance and allow for a wider production tolerance for the heating element. In some embodiments, the subject matter can improve usability by automatically compensating for changes in contact resistance, thus requiring less frequent contact cleaning. In some embodiments, the subject matter enables measuring the heater element while heating. For example, power can be provided to the heater without interruption, and the heater power can be directly measured during heating. Due to the DC output of the converter, a simpler measurement circuit can be achieved. In some embodiments, the subject matter can achieve a longer battery pack runtime, allowing a battery pack cell to discharge deeper under load to 3.0 V or even lower to achieve a longer runtime within the target performance, and / or achieve improved performance at low ambient temperatures (e.g., in cold weather). For example, the battery pack voltage may drop at low temperatures, and the converter can still maintain a consistent power to the heater and / or provide a longer runtime at low temperatures. In some embodiments, the present subject matter can improve the cycle life of a battery pack, reduce the stress on the battery pack due to lower peak discharge current, achieve higher system integration (e.g., a charger and a heater power control can be built into an integrated DC-DC converter), charge and power a heating element using the same single inductor (i.e., an inductor shared by the charger and the heater power control), and / or reduce the board area required for heater control, which can allow for a larger battery pack capacity or a smaller device and / or reduce the total cost. Compared to a linear charger, some embodiments can achieve less heat dissipation during charging, less heat transfer to a charger temperature sensor (usually a negative temperature coefficient (NTC) mounted on a battery in the battery pack) allows for accurate battery pack temperature measurement, achieve high charging efficiency of a charging accessory powered by a battery pack, and / or save energy. Some embodiments can provide alternative heater resistance measurement with low excitation current and no self-heating, which can be implemented by adding at least a resistor in series with the heater and a power FET. The present subject matter relates to heating control of an evaporator atomizer using a direct current to direct current (DC-DC) converter and a power monitor, which can measure the current through the heater and the voltage across the heating element to calculate power and resistance. The output voltage of the converter can be controlled to maintain a target power and / or a target temperature across the heating element. By using DC-DC converter control, the present subject matter can achieve one or more of the following: continuous heater resistance and temperature monitoring during power changes, provide faster preheating and uniform power distribution at low battery pack voltage and temperature, combine charger and heater control circuits to achieve cost and space reduction, compensate for increased cartridge contact resistance and improve the user experience, allow for a higher heater TCR when the heating element is near ambient temperature without overloading the battery pack, improve efficiency at low battery pack voltage, improve battery pack runtime, provide consistent performance at lower temperatures; extend battery pack life, and the like. FIG. 2 is a system block diagram of an example heater power control 200 according to some aspects of the present subject matter. The heater power control 200 can include a buck-boost DC-DC converter 205 and a power monitor 210. In some embodiments, the heater power control 200 is part of the circuit of the controller 104 described above. The converter 205 can be electrically coupled to a power source (e.g., a battery pack 215 and / or a universal serial bus (USB) power source 220) and a heating element 225 residing in a cartridge 230. The converter 205 can be coupled to the heating element 225 via a contact 235. The converter can receive a first voltage (e.g., V BATor V USB ) and supply a second voltage (e.g., V HEAT+ ) to the heating element 225. The power monitor 210 may be electrically coupled to the heating element 225 and may include a microprocessor 211, an analog-to-digital converter 212, and an analog front end 213. The power monitor 210 may measure a current through the heating element 225, measure a voltage across the heating element (e.g., from V HEAT+ to V HEAT- voltage drop), calculate a power and / or resistance, and output a control signal (e.g., DC EN) to the converter 205. The converter 205 may be controlled by a control signal (e.g., DC EN) to vary the second voltage (e.g., V HEAT+ ) to maintain a target power or a target temperature across the heating element 225. By using the converter 205 and the power monitor 210 to maintain a target power or a target temperature across the heating element 225, an improved evaporator atomizer can be achieved. In some embodiments, the converter 205 may include an energy storage component 240. For example, the converter 205 may utilize a capacitor in a switched capacitor or a charge pump topology as an energy storage component 240. However, to limit the peak current drawn from the battery pack 215 and as depicted in FIG. 2, the converter 205 may include an inductor as an energy storage component 240. An inductor-based converter can be used to reduce the voltage (e.g., step-down), increase the voltage (e.g., step-up), or regulate within the battery pack voltage range (e.g., buck-boost). In some embodiments, a closed-loop control of the converter 205 may be implemented using the power monitor 210, which includes analog circuitry for measuring voltage and current and outputting an analog signal to control the converter. In some embodiments, the closed-loop control may be implemented using, for example, an analog front end (AFE) circuit to obtain voltage and current information. The power monitor 210 may include a digital converter 212 having a digital control output signal (such as a PWM, digital-to-analog conversion (DAC) signal, or an inter-integrated circuit formatted signal (I2C)). The power monitor 210 may measure the voltage across the heating element 225 and the current through the heating element 225 to calculate the electrical power dissipated in the heating element 225 and the resistance of the heating element 225. Different from the conventional PWM method, this can be continuously performed without interruption to the power of the heating element. In some embodiments, the subject matter can utilize a 4-wire (Kelvin) connector (e.g., four contacts 235) to perform accurate voltage measurements above the heating element 225. In some embodiments, the subject matter can utilize a 2-wire chamber connector (e.g., two contacts 235) or a 3-wire connector. In some embodiments, a 5 V power supply can be provided, enabling the DC-DC converter 205 to charge other electronic devices from the internal battery pack 215. In this case, the converter outputs 5 V as a USB power supply. In this embodiment, the converter can operate in one of three modes: 1) as a charger; 2) for heater control; or 3) as a USB power supply. Some embodiments can allow for a higher heater TCR. A higher TCR can provide a larger ∆R / ∆T signal (change in resistance / change in temperature) and a more accurate temperature measurement. Some embodiments can allow for chamber contact resistance diagnosis, where changes in the output current can be analyzed to sense an increase in contact resistance. Figure 3 is a diagram showing one of the operating modes of the example heater power control 200 depicted in Figure 2. For a device in the off "transport" mode, during charger connection (e.g., charging mode), during抽吸, during a charger disconnection ("discharge mode"), at rest, the charging mode and at rest are shown as voltage versus time. In some embodiments, the DC-DC converter can be used as a constant current source. In some embodiments, the DC-DC converter can provide a constant current to measure the heater resistance between puffs. This can convert a constant voltage output into a current source. Figure 4 is a system block diagram of an example heater control 400 where the converter 205 operates as a current source. The example heater control 400 includes a resistor 405 and a switch 410 (MOSFET) positioned in series with the heating element 225. The switch 410 is controlled by the power monitor 210. The current can be set by the value R of the resistor 405 ISET and in some embodiments, can be selected to be from about 10 mA to 100 mA. The power monitor 210 can measure the voltage across the heating element 225 and the current through the heating element 225 to calculate the resistance. In an example embodiment, a heating element 225 can include a positive resistance temperature coefficient (TCR) with a temperature increase of +5% at a temperature 250ºC higher than the ambient temperature. At the operating temperature, the heater power can be 8 watts (W), and the resistance (R) of the heating element 225 h) = 0.5 ohms (Ω) and the parasitic resistance Rp = 0.35 Ω. The voltage across the heater can be initially set to 2.00 V. As the heating element 225 warms up, its resistance increases to 0.525 Ω = 0.5 Ω * 1.05, and the heater voltage also increases to 2.05 V to maintain 8 W across the heater. It should be noted that the actual output voltage of the DC - DC converter is higher (2.80 V at the start of heating and 2.83 V at the target temperature) to compensate for the voltage drop across the parasitic resistance. Assuming a 93% efficient DC - DC converter, the overall efficiency of this DC - DC circuit can be approximately 56%, or about 15% lower than PWM control, which is described more fully below. To increase efficiency, the output voltage might be increased to 4.5 V. This might cause R h to increase to 2.11 Ω. The average efficiency increases to approximately 75%. In this case, the converter efficiency is about 4% higher than the PWM efficiency. In some embodiments, a higher heater resistance can be used for high efficiency, a power monitor can be incorporated into the filter to improve voltage and current measurement accuracy, and the subject matter can utilize a converter with an improved internal power field - effect transistor (FET) design to reduce the on - resistance R DS(on) and speed up switching to achieve higher efficiency. In some embodiments, a hybrid heater control can be achieved by combining a DC - DC converter with a PWM control circuit to improve the overall efficiency of an evaporator device. For example, PWM can be used at high battery pack voltages and provide a boost or compensate for an increase in the cabin contact resistance at low battery pack voltages or low temperatures. The DC - DC converter can be set to operate at a relatively high efficiency (for the DC - DC converter) and can be turned on and off when less than full output power is needed. In this way, the PWM control circuit can supplement the DC - DC converter in providing power to the heating element, or can provide PWM power to the heating element only when the DC - DC converter is off. In some embodiments, a hybrid heater control method includes measuring a power supply output voltage (e.g., a battery pack output voltage) and selecting an operating circuit (e.g., by using a controller or by using an automatic voltage switch) to supply power to a heating element. In some embodiments, the method includes supplying power to the heating element using a PWM control circuit at a power supply output voltage greater than or equal to 4.0 V, and supplying power to the heating element using a DC-DC converter control circuit when the power supply output voltage is less than 4.0 V. In some embodiments, the method includes supplying power to the heating element using a PWM control circuit at a power supply output voltage greater than or equal to 3.8 V, and supplying power to the heating element using a DC-DC converter control circuit when the power supply output voltage is less than 3.8 V. In some embodiments, the method includes supplying power to the heating element using a PWM control circuit at a power supply output voltage greater than or equal to 3.6 V, and supplying power to the heating element using a DC-DC converter control circuit when the power supply output voltage is less than 3.6 V. In some embodiments, the method includes supplying power to the heating element using a PWM control circuit at a power supply output voltage greater than or equal to 3.4 V, and supplying power to the heating element using a DC-DC converter control circuit when the power supply output voltage is less than 3.4 V. In some embodiments, a hybrid heater control method includes: measuring (e.g., by using a controller) a duty cycle of a PWM control circuit; supplying power to a heating element; and switching to a DC-DC converter control circuit to supply power to the heating element when the duty cycle is greater than 85%. In some embodiments, the hybrid heater control method includes: measuring (e.g., by using a controller) a duty cycle of the PWM control circuit; supplying power to the heating element; and switching to the DC-DC converter control circuit to supply power to the heating element when the duty cycle is greater than 90%. In some embodiments, the hybrid heater control method includes: measuring (e.g., by using a controller) a duty cycle of a PWM control circuit; supplying power to the heating element; and switching to the DC-DC converter control circuit to supply power to the heating element when the duty cycle is greater than 95%. In some embodiments, the hybrid heater control method includes: measuring (e.g., by using a controller) a duty cycle of the PWM control circuit; supplying power to the heating element; and switching to the DC-DC converter control circuit to supply power to the heating element when the duty cycle is greater than 98%. In some embodiments, the hybrid heater control method includes: measuring (e.g., by using a controller) a duty cycle of a PWM control circuit; supplying power to the heating element; and switching to the DC-DC converter control circuit to supply power to the heating element when the duty cycle is approximately 100%. FIG. 5 is a flowchart of an example process 500 for operating a heater control in accordance with some aspects of the present subject matter. At 510, a current through a heating element of an evaporator atomizer may be measured. The current may be supplied by a converter configured to be electrically coupled to a power source and the heating element. The converter may be further configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter may be a DC-to-DC converter. At 520, a voltage above the heating element may be measured. At 530, a power and / or resistance may be calculated. At 540, the operation of the converter may be controlled to vary the second voltage to maintain a target power or a target temperature above the heating element. The following includes an example PWM control implementation that may supplement the DC-DC converter in providing power to the heating element, or may provide PWM power to the heating element only when the DC-DC converter is off. A typical lithium-ion battery pack cell has an operating voltage range from about 4.2 V to 3.0 V as it discharges from full to empty. To ensure sufficient voltage to reach a target power and temperature, the resistance (Rh) of the heating element is selected for the minimum operating voltage at the maximum PWM duty cycle (D). The current and power in the PWM pulse are proportional to the voltage and are given by Ohm's law Ih = Vb / R, where: Ih is the current, Vb is the battery pack voltage, and R is the resistance. R includes all the resistances in the electrical power path between the positive and negative terminals of the chemical cell and the atomizer. In some embodiments, the resistance R may be expressed as the sum of the following resistances: Rb: internal battery impedance (DCIR); Rs: battery pack safety electronics, FET, and PWM switch; Rt: conductor resistance, wires, PCBA traces, electrical interconnects; Rc: chamber contact resistance; and Rh: resistive heating element (atomizer). For simplicity, the parasitic resistance may be expressed as Rp = Rb + Rs + Rt + Rc. Then, the total resistance in the circuit is R = Rh + Rp. FIG. 6 shows an example circuit diagram that shows the resistances and related parameters in an example electrical power path and includes a power control switch. It should be noted that the resistances in the positive and negative rails are represented as a single resistance in the calculation. For PWM control calculations and for a target power of 8.0 W at the heating element, the power from the battery pack can be expressed as Pb = Ph + Pp, where: Pb is the power drawn from the battery pack, Ph is the power above the heating element and Pp is the power loss of the sum of all parasitic resistances. Similarly, the battery pack voltage Vb can be expressed as a sum of the voltage Vh above the heating element and the voltage Vp above the parasitic resistance when Vb = Vh + Vp. Vh = Rh*I and Vp = Rp*I can be substituted to derive Vb = I*(Rh + Rp). Rh can be selected at the maximum duty cycle and the minimum battery pack voltage, such as Ph ≥ 8.0 W, where Rb = 200 mΩ (for small lithium-ion batteries); Rs = 60 mΩ; Rt = 60 mΩ; Rc = 30 mΩ; Rp = 0.35 Ω. R = 0.50 Ω can be selected at a minimum battery pack voltage of 3.40 V. The total resistance in the circuit is R = Rp + Rh = 0.35 Ω + 0.5 Ω = 0.85 Ω. The peak current in the PWM pulse during heating is I = 3.4 V / 0.85 Ω = 4.0 A. For the above example, this is the current at different states of charge: 4 A at the minimum battery pack voltage of 3.4 V; 5.28 A at the average battery pack voltage of 3.7 V; and 6.74 A at the maximum battery pack voltage of 4.2 V. The average power drawn from the battery pack at 3.70 V is 11.22 W, where the electrical efficiency is 71.3%. It should be noted that the power loss is independent of the duty cycle, because the power to the heating element is only delivered in the PWM pulse. Depending on the desired configuration, the subject matter described herein may be embodied in a system, apparatus, method, and / or article. The embodiments set forth in the foregoing description do not represent all embodiments consistent with the subject matter described herein. On the contrary, they are only some examples consistent with aspects of the described subject matter. Although some variations have been described in detail above, other modifications or additions are possible. In particular, further features and / or variations may be provided in addition to the features and / or variations described herein. For example, the embodiments described above may relate to various combinations and sub-combinations of the disclosed features and / or combinations and sub-combinations of several further features disclosed above. Additionally, the logical flows depicted in the figures and / or described herein need not be in the particular order shown or sequential order to achieve the desired result. Other embodiments may be within the scope of the following claims of the invention. The term When a feature or element is referred to herein as being “on” another feature or element, it can be directly on the other feature or element or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being “directly on” another feature or element, no intervening features or elements are present. It will also be understood that when a feature or element is referred to as being “connected”, “attached” or “coupled” to another feature or element, it can be directly connected, attached or coupled to the other feature or element, or intervening features or elements may be present. In contrast, when a feature or element is referred to as being “directly connected”, “directly attached” or “directly coupled” to another feature or element, no intervening features or elements are present. Although described or shown with respect to one embodiment, the features and elements so described or shown can be applied to other embodiments. Those skilled in the art will also understand that a structure or feature referred to as being “adjacent” to another feature can have portions that overlap with or are below the adjacent feature. The terminology used herein is for the purpose of describing particular embodiments and implementations only and is not intended to be limiting. For example, as used herein, unless the context clearly dictates otherwise, the singular forms “a”, “an” and “the” are also intended to include the plural forms. In the above description and the claims of the invention, phrases such as “at least one of...” or “one or more of...” may appear after a list of elements or features. The term “and / or” may also appear in a list of two or more elements or features. Unless implicitly or explicitly contrary to the context in which it is used, this phrase is intended to mean either individually listed elements or features, or any combination of the individually listed elements or features with any of the other individually listed elements or features. For example, the phrases “at least one of A and B”; “one or more of A and B”; and “A and / or B” are each intended to mean “only A, only B, or A and B together”. A similar interpretation is intended for lists containing three or more items. For example, the phrases “at least one of A, B and C”; “one or more of A, B and C”; and “A, B and / or C” are each intended to mean “only A, only B, only C, A and B together, A and C together, B and C together, or A and B and C together”. The term “based on” as used above and in the claims of the invention is intended to mean “at least in part based on”, such that an unrecited feature or element is also permitted. For ease of description, spatial relative terms such as "front", "back", "beneath", "below", "lower", "above", "upper", and the like may be used herein to describe the relationship of one element or feature to another (other) element or feature, as illustrated in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation other than the orientation depicted in the figures. For example, if a device in the figures is inverted, an element described as "beneath" or "under" another element or feature will be oriented "above" the other element or feature. Thus, the exemplary term "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein can be interpreted accordingly. Similarly, the terms "upward", "downward", "vertical", "horizontal", and the like are used herein for purposes of explanation only unless specifically indicated otherwise. Although the terms "first" and "second" may be used herein to describe various features / elements (including steps), these features / elements should not be limited by these terms unless the context otherwise indicates. These terms may be used to distinguish one feature / element from another feature / element. Thus, without departing from the teachings provided herein, a first feature / element discussed below may be termed a second feature / element, and similarly, a second feature / element discussed below may be termed a first feature / element. As used in the specification and the claims of the invention, including as used in the implementation and unless otherwise specifically designated, all numbers can be construed as if prefaced by the word "about" or "approximately", even if the term does not explicitly appear. When describing a magnitude and / or a position, the phrase "about" or "approximately" can be used to indicate that the described value and / or position is within a reasonable expected range of the value and / or position. For example, a numerical value can have a value of + / −0.1% of the specified value (or value range), + / −1% of the specified value (or value range), + / −2% of the specified value (or value range), + / −5% of the specified value (or value range), + / −10% of the specified value (or value range), etc. Unless the context otherwise indicates, any numerical value given herein should also be understood to include about or approximately that value. For example, if the value "10" is disclosed, then "about 10" is also disclosed. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. It should also be understood that, as would be appropriately understood by one of ordinary skill in the art, when a value "less than or equal to" that value is disclosed, "greater than or equal to that value" and the possible ranges between the values are also disclosed. For example, if the value "X" is disclosed, then "less than or equal to X" and "greater than or equal to X" are also disclosed (e.g., where X is a numerical value). It should also be understood that throughout the application, the data is provided in several different formats, and this data represents endpoints and starting points, and ranges of any combination of data points. For example, if a particular data point "10" and a particular data point "15" are disclosed, then it should be understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15, as well as between 10 and 15, are considered disclosed. It should also be understood that each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed. Although the various illustrative embodiments are described above, various changes can be made to the embodiments without departing from the teachings herein. For example, in alternative embodiments, the order of performing the various described method steps can generally be changed, and in other alternative embodiments, one or more method steps can be skipped altogether. In some embodiments, optional features of the various device and system embodiments can be included, while in other embodiments they can be excluded. Therefore, the foregoing description is provided primarily for illustrative purposes and should not be construed as limiting the scope of the claims of the invention. One or more aspects or features of the subject matter described herein can be implemented in digital electronic circuitry, integrated circuitry, specially designed application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), computer hardware, firmware, software, and / or combinations thereof. These various aspects or features can include implementations in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special purpose or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. The programmable system or computing system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on respective computers and having a client-server relationship to each other. These computer programs (which may also be referred to as programs, software, software applications, applications, components, or code) include machine instructions for a programmable processor and can be implemented in a high-level procedural language, an object-oriented programming language, a functional programming language, a logical programming language, and / or combinations / machine language. As used herein, the term "machine-readable medium" refers to any computer program product, apparatus, and / or device used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal, for example, such as a magnetic disk, optical disk, memory, and programmable logic device (PLD). The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor. The machine-readable medium can store these machine instructions non-transitorily, for example, as a non-transitory solid state memory or a hard disk drive or any equivalent storage medium. Alternatively or additionally, the machine-readable medium can store these machine instructions in a transitory manner, for example, as a processor cache memory or other random access memory associated with one or more physical processor cores. The examples and illustrations contained herein show, in an illustrative and not restrictive manner, specific embodiments of the subject matter that can be practiced therein. As mentioned, other embodiments can be utilized and derived therefrom, such that structural and logical substitutions and changes can be made without departing from the scope of the present invention. For convenience only and without intending to voluntarily limit the scope of this application to any single invention or inventive concept (if more than one is in fact disclosed), these embodiments of the inventive subject matter may be referred to herein individually or collectively by the term "invention". Thus, although specific embodiments have been shown and described herein, any configuration calculated to achieve the same purpose may replace the specific embodiments shown. The present invention is intended to cover any and all adaptations or variations of various embodiments. After reviewing the foregoing description, combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art. The term "based on" as used herein and in the claims of the invention is intended to mean "at least in part based on", such that a feature or element not recited is also permitted. Depending on the desired configuration, the subject matter described herein may be embodied in a system, apparatus, method, and / or article. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. On the contrary, they are only some examples consistent with aspects of the described subject matter. Although some variations have been described in detail herein, other modifications or additions are possible. In particular, further features and / or variations may be provided in addition to those features and / or variations described herein. For example, the implementations described herein may relate to various combinations and sub-combinations of the disclosed features and / or combinations and sub-combinations of several further features disclosed herein. Additionally, the logical flows depicted in the figures and / or described herein need not be in the particular order shown or sequential order to achieve the desired result. Other implementations may be within the scope of the following claims of the invention. 100: Evaporator device 102: Evaporable material 104: Controller 105: Communication hardware 108: Memory 110: Evaporator body 112: Power supply 113: Sensor 116: Input device 117: Output 118: Cartridge receptacle 120: Evaporator cartridge 122: Insertable end 124a: Cartridge contact 124b: Cartridge contact 125a: Receptacle contact 125b: Receptacle contact 127: Seal 128: Charging contact 130: Mouthpiece 140: Reservoir 141: Atomizer 160: Bottom region / Pulse width modulation (PWM) heater control 162: Battery charger 164: Microcontroller 165: PWM metal oxide semiconductor field effect transistor (MOSFET) 172: Battery pack 174: Low dropout regulator (LDO) 180: Compartment 181: Contact 182: Current source 185: Voltage measurement point (VMEAS) analog front end (AFE) / Heating element 200: Heater power control 205: Buck-boost DC-DC converter 210: Power monitor 211: Microprocessor 212: Analog-to-digital converter 213: Analog front end 215: Battery pack 220: Universal serial bus (USB) power 225: Heating element 230: Compartment 235: Contact 240: Energy storage component 400: Heater control 405: Resistor 410: Switch 500: Program 510: Operation 520: Operation 530: Operation 540: Operation The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate specific aspects of the subject matter disclosed herein and, together with the [Embodiments], help to explain some of the principles associated with the disclosed embodiments. In the drawings: FIG. 1A is a block diagram of an evaporator device; FIG. 1B is a schematic diagram of an evaporator device and an evaporator cartridge; FIG. 1C is a front view of an embodiment of an evaporator device and an evaporator cartridge; FIG. 1D is a front view of an evaporator cartridge coupled to an evaporator device; FIG. 1E is a perspective view of an evaporator cartridge; FIG. 1F is a perspective view of another embodiment of an evaporator cartridge coupled to an evaporator device; FIG. 1G is a system block diagram illustrating an example PWM heater control; FIG. 2 is a system block diagram illustrating an example heater power control according to some aspects of the subject matter; FIG. 3 is a diagram illustrating the operating modes of the example heater control 200 depicted in FIG. 2; FIG. 4 is a system block diagram showing an example heater control in which the converter operates as a current source; FIG. 5 is a flowchart of an example procedure for operating a heater control in accordance with some aspects of the present subject matter; and FIG. 6 shows an example circuit diagram that shows resistors and related parameters in an example power path and includes a power control switch. In practice, like reference numerals denote like structures, features, or elements. Like reference numerals in the various figures indicate like elements. 160: Bottom region / pulse width modulation (PWM) heater control 162: Battery charger 164: Microcontroller 165: PWM metal oxide semiconductor field effect transistor (MOSFET) 172: Battery pack 174: Low dropout regulator (LDO) 180: Cabin 181: Contact 182: Current source 185: Voltage measurement point (VMEAS) analog front end (AFE) / heating element

Claims

1. A system for supplying power to an evaporator atomizer, comprising: A converter configured to be electrically coupled to a power supply and a heating element of an evaporator atomizer, the converter being further configured to receive a first voltage from the power supply and provide a second voltage to the heating element, the converter being a DC-DC converter and included in a DC-DC converter control circuit; a pulse width modulation (PWM) control circuit configured to be electrically coupled to the power supply and the heating element of the evaporator atomizer, the PWM control circuit being further configured to selectively provide PWM power to the heating element; and a circuit configured to be electrically coupled to the heating element, measuring a current or a voltage associated with the heating element and outputting a control signal to the converter, wherein the converter is further configured to be controlled by the control signal to change the second voltage to maintain a target power or a target temperature above the heating element, and wherein the system is configured to select either the DC-DC converter control circuit or the PWM control circuit to power the heating element.

2. The system of claim 1, wherein the converter includes a boost and / or a buck converter, the converter including an energy storage device.

3. The system of claim 2, wherein the energy storage device includes a capacitor in the form of a switching capacitor topology or a charge pump topology.

4. The system of claim 2, wherein the energy storage device includes an inductor.

5. The system of claim 1, wherein the circuit includes an analog circuit that forms a closed-loop control.

6. The system of claim 1, wherein the circuit comprises: an analog front-end circuit configured to measure the current through the heating element and the voltage above the heating element; and a digital converter comprising circuitry configured to provide the control signal based on the current measured through the heating element and the voltage measured above the heating element.

7. The system of claim 6, wherein the digitizer is configured to provide the control signal as a pulse width modulation signal, a digital-to-analog conversion signal, or an inter-integrated circuit formatting signal.

8. A system as claimed in any of claims 1 to 7, wherein the circuit continuously measures the current and the voltage without interrupting the power to the heating element.

9. The system of any one of claims 1 to 7 further includes: A microcontroller; A switch is provided between the converter and the heating element, the switch being electrically coupled to the microcontroller, the microcontroller being configured to apply a pulse width modulation signal to one gate of the switch.

10. The system of claim 9, wherein the converter is configured to operate at a first power level, and the microcontroller is configured to determine a second power level based on the current measured through the heating element and the voltage measured above the heating element, and to modify the pulse width modulation signal to control the switch to modify the second voltage.

11. A system as claimed in any of claims 1 to 7, wherein the converter is configured to provide uninterrupted power to the heating element during a heating cycle.

12. A system as claimed in any of claims 1 to 7, wherein the circuit is configured to determine a change in a contact resistance of a contact between the converter and the heating element based on a change in the measured current.

13. The system of any one of claims 1 to 7 further includes: A current source, configured to be coupled to the heating element, the current source comprising a current source resistor and a current source switch.

14. The system of any one of claims 1 to 7 further includes: A universal serial bus port including a universal serial bus power rail, the converter being configured to output a third voltage to the universal serial bus power rail.

15. A method for supplying power to an evaporator atomizer, comprising: When the heating element is electrically coupled to the converter, a current or voltage related to the heating element of an evaporator atomizer is measured by the circuit. The converter is also configured to be electrically coupled to a power source. The converter is further configured to receive a first voltage from the power source and provide a second voltage to the heating element. The converter is a DC-DC converter included in a DC-DC converter control circuit. The circuit is configured to be electrically coupled to the heating element. A pulse width modulation (PWM) control circuit is configured to be electrically coupled to the power source and the heating element of the evaporator atomizer. The PWM control circuit is further configured to selectively provide PWM power to the heating element. The DC-DC converter control circuit or the PWM control circuit is selected to power the heating element. The circuit and the converter change the second voltage to maintain a target power or a target temperature above the heating element.

16. The method of claim 15, wherein the converter includes a boost and / or a buck converter, the converter including an energy storage device.

17. The method of claim 16, wherein the energy storage device includes a capacitor in the form of a switching capacitor topology or a charge pump topology.

18. The method of claim 16, wherein the energy storage device includes an inductor.

19. The method of claim 15, further comprising: A control signal is provided to the converter as a pulse width modulation signal, a digital-to-analog conversion signal, or an inter-integral formatting signal.

20. The method of claim 15, further comprising: A pulse width modulation signal is applied to the gate of a switch coupled between a microcontroller, the converter, and the heating element.

21. The method of claim 20, wherein the converter is configured to operate at a first power level, and the microcontroller is configured to determine a second power level based on a measured current and a measured voltage associated with the heating element, and to modify the pulse width modulation signal to control the switch to modify the second voltage.

22. The method of claim 15, wherein the converter is configured to provide uninterrupted power to the heating element during a heating cycle.

23. The method of claim 15, further comprising: The change in contact resistance between the converter and the heating element is determined based on the change in the measured current.

24. The method of any of claims 15 to 23, wherein measuring the voltage associated with the heating element includes measuring the voltage associated with the heating element using a 4-wire connector.

25. The method of any of claims 15 to 23, wherein measuring the voltage associated with the heating element includes measuring the voltage associated with the heating element using a 3-wire connector.

26. The method of any one of claims 15 to 23, wherein measuring the current associated with the heating element includes continuously measuring the current through the heating element without interrupting the power to the heating element.

27. The method of any one of claims 15 to 23, wherein measuring the voltage associated with the heating element includes continuously measuring the voltage associated with the heating element without interrupting the power of the heating element.

28. The method of any of claims 15 to 23, wherein the power source is a battery.

29. The method of any one of claims 15 to 23, further comprising: The circuit measures the power supply output voltage and selects an operating circuit to supply power to the heating element, wherein when the power supply output voltage is greater than or equal to 4.0V, the operating circuit is the PWM control circuit, and wherein when the power supply output voltage is less than 4.0V, the operating circuit is the DC-DC converter control circuit including the DC-DC converter.

30. The method of any one of claims 15 to 23, further comprising: Measure the power supply output voltage; The operating circuit selects an operating circuit to supply power to the heating element, wherein when the power supply output voltage is greater than or equal to 3.8V, the operating circuit is the PWM control circuit, and wherein when the power supply output voltage is less than 3.8V, the operating circuit is the DC-DC converter control circuit including the DC-DC converter.

31. The method of any one of claims 15 to 23, further comprising: Measure the power supply output voltage; The operating circuit selects an operating circuit to supply power to the heating element, wherein when the power supply output voltage is greater than or equal to 3.6V, the operating circuit is the PWM control circuit, and wherein when the power supply output voltage is less than 3.6V, the operating circuit is the DC-DC converter control circuit including the DC-DC converter.

32. The method of any one of claims 15 to 23 further includes: Measure the power supply output voltage; The operating circuit selects an operating circuit to supply power to the heating element, wherein when the power supply output voltage is greater than or equal to 3.4V, the operating circuit is the PWM control circuit, and wherein when the power supply output voltage is less than 3.4V, the operating circuit is the DC-DC converter control circuit including the DC-DC converter.

33. The method of any one of claims 15 to 23, further comprising: Measure the duty cycle of one of the PWM control circuits; and when the duty cycle is greater than 85%, select the DC-DC converter control circuit that includes the DC-DC converter.

34. The method of any one of claims 15 to 23, further comprising: Measure the duty cycle of one of the PWM control circuits; and when the duty cycle is greater than 90%, select the DC-DC converter control circuit that includes the DC-DC converter.

35. The method of any one of claims 15 to 23, further comprising: Measure the duty cycle of one of the PWM control circuits; and when the duty cycle is greater than 95%, select the DC-DC converter control circuit that includes the DC-DC converter.

36. The method of any one of claims 15 to 23, further comprising: The duty cycle of one of the PWM control circuits is measured; and when the duty cycle is greater than 98%, the DC-DC converter control circuit including the DC-DC converter is selected.

37. The method of any one of claims 15 to 23, further comprising: Measure the duty cycle of one of the PWM control circuits; and when the duty cycle is approximately 100%, select the DC-DC converter control circuit that includes the DC-DC converter.

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