EA043023B1 - HEATER CONTROL IN AEROSOL GENERATING DEVICE - Google Patents

Description

The field of technology to which the invention belongs

The present invention relates to aerosol generating devices and more particularly to heater control systems for aerosol generating devices.

Background of the invention

Aerosol generating devices such as electronic cigarettes and other aerosol inhaling or vaporizing devices are becoming consumer products gaining popularity.

Heating devices for evaporation or aerosolization are known from the prior art. Such devices typically include a heater configured to heat the vaporized product. During operation, the product to be evaporated is heated by the heater, which vaporizes the constituents of the product that the user inhales. In some examples, the product may contain tobacco and may be similar to a traditional cigarette, in other examples, the product may be liquids or liquid encapsulated.

There is a need for more precise control of the heater in such devices. Therefore, the aim of the invention is to solve such a problem.

The essence of the invention

According to an aspect of the present invention, a control device for an aerosol generating device is provided, wherein the control device comprises a main control unit and is configured to be connected to a battery and a heating coil, wherein the main control unit is configured to perform one or more execution cycles, wherein the first actuating the cycle of one or more execution cycles includes the following steps: application of the first output power to the heating coil for the first number of steps of the first execution cycle; turning off the first power output and thereby turning off the heating coil in a second number of steps of the first execution cycle; measuring a first heating coil voltage of said heating coil in a third number of steps of the first execution cycle; suspending with the heater coil off for a fourth number of steps of the first execution cycle and measuring the first no-load battery voltage in the fifth number of steps of the first execution cycle; wherein the main control unit is further configured to calculate an updated power output based on the first heating coil voltage and the first no-load battery voltage.

Thus, the pause between the heater coil voltage measurement and the no-load battery voltage measurement allows the no-load battery voltage to be measured separately from the heater coil voltage, so that the heater coil voltage is measured immediately after heating, giving the battery time to recover without an applied heating load (i.e. . in unloading state) before measuring the battery voltage without load. This allows you to accurately measure both the voltage of the heating coil and the voltage of the battery without load. Preferably, each step corresponds to a predetermined amount of time or step frequency (ie, the number of steps occurring in 1 second).

Preferably, the main control unit is further configured to apply an updated power output to the heating coil in a subsequent firing cycle that follows the first firing cycle.

Thus, the calculation of the updated output power can be performed separately from the first execution cycle; thus, the calculations necessary to determine the subsequent power output for the next execution cycle can be separated from the first execution cycle so that the processing necessary for the calculations does not interfere with the critical steps of the first execution cycle. If the updated power is applied in an execution cycle immediately after the first execution cycle, delays may occur due to the main control unit processing the calculation of the updated power; separation prevents this.

Preferably, the switching off of the first power output and thus the switching off of the heating coil in the second number of stages occurs after the first number of stages of the first execution cycle.

Preferably, the measurement of the first heating coil voltage of said heating coil in a third number of stages occurs after the second number of stages of the first execution cycle with a lower output power than the first output power supplied to the heating coil.

Preferably, the heater coil off suspension for the fourth number of steps occurs after the third number of steps of the first execution cycle.

Preferably, the measurement of the first off-load battery voltage in the fifth number of steps occurs after the fourth number of steps of the first execution cycle, the off-load battery voltage corresponding to an off-load state of the battery in which no heating load is applied.

- 1 043023

Preferably, each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period.

Preferably, the main control unit is further configured to calculate an updated power output based on the first heating coil voltage and the first no-load battery voltage in a calculation cycle separate from one or more execution cycles.

Thus, the calculations necessary to determine the updated output power can be separated from one or more execution cycles such that the processing necessary for the calculations does not interfere with critical steps of one or more execution cycles.

Preferably, the main control unit is configured to perform a calculation cycle and one or more execution cycles using separate processing functionality.

A compute cycle may take longer to complete than an execution cycle. Thus, the implementation of calculations in the calculation cycle using separate processing functionality prevents the calculation cycle from interfering with the execution cycle. Thus, the aerosol generating device can continue to function simultaneously with the calculation.

Preferably, the main control unit is further configured to perform a second execution cycle, where the first execution cycle is offset from the next by at least a second execution cycle, and wherein the second execution cycle includes: applying the first output power to the heating coil during the first number of stages of the second execution cycle; and wherein the main control unit performs the calculation cycle at least partially in parallel with the second execution cycle.

Thus, the second execution cycle allows the aerosol generating device to continue operating while the updated power output is calculated for the subsequent execution cycle, i.e. updated output power calculations may be performed during execution of the second execution cycle rather than by processing the calculations as part of the first execution cycle, which may result in processing delays during the steps of the first execution cycle or when the second execution cycle is started.

By applying the second output power during the second execution cycle, the aerosol generating device can continue to apply output power to the heating coil while an updated output power is calculated for the subsequent execution cycle.

Preferably, the main control unit is further configured to perform a third execution cycle between the first execution cycle and a subsequent execution cycle, where the third execution cycle includes applying the first output power to the heating coil during the first number of steps of the third execution cycle and updating the first output power to the updated output power in a response to determining that the updated power output is available from the computing cycle.

Thus, the controller continues to apply output power to the heating coil until an updated output power is calculated; then the output power is promptly updated.

Preferably, the first power output may be updated to the updated power output at the end of the third execution cycle. For example, the first output power may be updated to the updated output power in the fifth number of steps of the third execution cycle. The start of each execution cycle may be hardware triggered, in which case there is no time to update the output power at the beginning of the execution cycle. For example, updating the first output at the start of a subsequent cycle may result in delays in application of the heater output. Thus, it is advantageous to update the power output at the end of an execution cycle for use in the next execution cycle. Thus, delays in applying the updated output power are eliminated.

Preferably, the third execution cycle may be carried out between the second execution cycle and the subsequent execution cycle. Additional execution cycles may be performed between the first execution cycle and the third execution cycle, using the first output power, until the computational cycle makes the updated output power available.

Preferably, each power output is a pulse width modulated output signal with an associated duty cycle.

Thus, pulse width modulation can be used to effectively control the power supplied to the heater. Preferably, updating the output power may include updating the associated duty cycle.

- 2 043023

Preferably, the main control unit is configured to calculate the heater coil temperature based on the resistance of the heater coil, and is further configured to calculate an updated power output based on the difference between the calculated heater coil temperature and the target heater coil temperature.

In this way, the actual temperature of the heating coil can be accurately determined, i.e. heating coil temperature during heating. Further, based on this, an updated power output or duty cycle can be calculated to provide a heating coil power level to achieve a target heating coil temperature. Preferably, the temperature of the heating coil can be calculated in the calculation cycle. Preferably, the updated power output may be based on the difference between the calculated heater coil temperature and the target heater coil temperature calculated in the computing cycle.

Preferably, the control device further comprises a heating coil sensing subcircuit, wherein the heating coil sensing subcircuit comprises a battery terminal connected to the heating coil and a test resistor located therebetween.

In this way, the voltage across the heating coil can be accurately measured.

Preferably, the heater coil sensing subcircuit is configured to apply less power than the first power output to the heater coil to measure the first heater coil voltage.

Thus, a controlled potential can be applied to the coil when the heating coil is turned off; this allows accurate measurement of the heating coil voltage while the battery is recovering. Preferably, the heating coil sensing subcircuit may further comprise a second transistor, wherein the second transistor is configured to switch a relatively lower current. In this way, the current used to measure the heating coil voltage can be carefully controlled. Preferably, the power supplied by the heating coil sensing subcircuit may be extremely small compared to the first power output. Preferably, the second transistor may be a MOSFET.

Preferably, the main control unit is configured to calculate the heating coil resistance based on the first heating coil voltage, the test resistor resistance, and the first no-load battery voltage.

Preferably, the main control unit is configured to calculate the resistance, RCOIL, of the heating coil based on the first heating coil voltage, VCOIL, the resistance, RTEST, test resistor, and the first voltage, VOFFLOAD, of the no-load battery as:

_D _ (^co/l) Cutest) _d ^K COIL - 77 77 ^SERIES ^OFFLOAD ^{- V} COIL where RSERIES is the known resistance of the electrical contacts that are in series with the heating coil but that contribute to the measured voltage VCOIL. RSERIES should not change significantly with temperature, measured during manufacture and stored in the electronic circuitry of the capsule.

Thus, the heater coil voltage can be used along with the test resistor and the measured no-load battery voltage to determine the heater coil resistance. Preferably, the resistance of the test resistor may be a known value stored in the main control unit. Preferably, the resistance of the heating coil can be calculated in the computing loop.

Preferably, the main control unit is further configured to, in a second number of steps, set the heating coil to high voltage and measure the first battery voltage under load before turning off the heating coil.

The battery voltage under load corresponds to the voltage when the heating load is applied, i.e. when the battery is under load. The measured battery voltage when a heating load is applied can be used to accurately determine the updated power output. Preferably, the heating coil can be set to high voltage only for a short time, on the order of microseconds; this may have a slight heating effect, while still ensuring that the battery is under load during the measurement.

Preferably, the control device further comprises a first transistor, wherein the pulse width modulation input signal switches the first transistor to provide a pulse width modulation output signal to the heating coil.

Thus, the low current output of the main control unit can switch the higher current associated with the heater via pulse width modulation. Preferably, the first transistor may be a MOSFET. More preferably, the PWM input can be connected between the main control unit and the vacuum gate of the MOSFET, the battery is connected to the source of the MOSFET, and the heating coil is connected to the drain of the MOSFET.

- 3 043023

According to another aspect of the present invention, an aerosol generating device is provided, comprising a control device according to the previous aspect.

According to another aspect of the present invention, there is provided a method for operating a control device of an aerosol generating device, the method comprising, in a first execution cycle, performing the steps of: applying a first power output to a heating coil for a first number of steps of the first execution cycle; turning off the first power output and thereby turning off the heating coil in a second number of steps of the first execution cycle; measuring a first heating coil voltage of said heating coil in a third number of steps of the first execution cycle; suspending with the heater coil off for a fourth number of steps of the first execution cycle and measuring the first no-load battery voltage in the fifth number of steps of the first execution cycle; the method further comprising calculating the updated power output based on the first heating coil voltage and the first no-load battery voltage.

Thus, the pause between the heater coil voltage measurement and the no-load battery voltage measurement allows the no-load battery voltage to be measured separately from the heater coil voltage, so that the heater coil voltage is measured immediately after heating, giving the battery time to recover without an applied heating load (i.e. . in unloading state) before measuring the battery voltage without load. This allows you to accurately measure both the voltage of the heating coil and the voltage of the battery without load. Preferably, each step may correspond to a predetermined amount of time or step frequency (ie, the number of steps occurring in 1 second).

Preferably, the switching off of the first power output and thus the switching off of the heating coil in the second number of stages occurs after the first number of stages of the first execution cycle.

Preferably, the measurement of the first heating coil voltage of said heating coil in a third number of stages occurs after the second number of stages of the first execution cycle with a lower output power than the first output power supplied to the heating coil.

Preferably, the heater coil off suspension for the fourth number of steps occurs after the third number of steps of the first execution cycle.

Preferably, the measurement of the first off-load battery voltage in the fifth number of steps occurs after the fourth number of steps of the first execution cycle, the off-load battery voltage corresponding to the off-load state of the battery in which no heating load is applied.

Preferably, each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period.

According to another aspect of the present invention, a persistent computer-readable medium is provided that stores instructions that, when executed by one or more processors, cause the one or more processors to execute in a first execution cycle:

applying the first power output to the heating coil for the first number of steps of the first execution cycle;

turning off the first power output and thereby turning off the heating coil in a second number of steps following the first number of steps of the first execution cycle;

measuring a first heating coil voltage of said heating coil in a third number of steps following a second number of steps of a first execution cycle with an output power less than the first output power supplied to the heating coil;

suspending with the heating coil off for a fourth number of steps following the third number of steps of the first execution cycle; and measuring a first no-load battery voltage in a fifth number of steps following the fourth number of steps of the first execution cycle, the no-load battery voltage corresponding to an no-load state of the battery in which no heating load is applied;

wherein each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period, and further includes calculating an updated output power based on the first heating coil voltage and the first no-load battery voltage.

Preferably, each step corresponds to an integer number of pulse width modulation (PWM) cycles, with each PWM cycle having an on period and an off period forming a PWM cycle. Preferably, each stage corresponds to one PWM cycle.

Brief description of graphic materials

Embodiments of the present invention are described below by way of example with reference to

- 4 043023 graphic materials, in which:

in fig. 1 is a block diagram of an aerosol generating device according to an embodiment of the invention;

in fig. 2 is a schematic diagram of a control device of an aerosol generating device according to an embodiment of the invention;

in fig. 3 is a flowchart of a method for controlling a heater of an aerosol generating device according to an embodiment of the invention;

in fig. 4 is a conceptual timing diagram of a heater control method in accordance with one embodiment of the invention;

in fig. 5 is a block diagram of the processes involved in the execution cycle; and in FIG. 6 is a block diagram of the processes involved in the computing cycle.

Detailed description

In FIG. 1 is a block diagram of the components of an aerosol generating device or electronic cigarette. The aerosol generating device includes a heater 106 (also referred to as a heating coil), a control device 104, and a battery 102. The battery 102 provides power to the heater 106 and the control device 104. The control device 104 includes a main control unit 108 and control electronics 110 configured with the ability to control the heater 106 and to control the power supply to the heater 106 from the battery 102. In the example, the main control unit 108 is a microcontroller unit. In an example, the aerosol generating device is configured to receive a capsule containing a vapor generating material; in such an example, the heater 106 may be positioned within the capsule as a component of the capsule and connected to the aerosol generating device by an electrical connection. The capsule may also contain capsule electronics that store information about the capsule that can be read by the microcontroller unit 108 of the aerosol generating device.

The heater 106 is configured to aerosolize or vaporize the vapor generating material. The vapor generating material may be a solid, such as tobacco, a liquid, such as a vaporizable liquid, or any other suitable type of vaporizable material. It should be understood that for the purposes of this description, the terms vapor and aerosol are used interchangeably.

In FIG. 2 is a circuit diagram illustrating a control device 104 for a device generating steam. The control device 104 includes a main control unit 108 and control electronics 110.

The control electronics includes a first transistor or main MOS transistor 206 in connection with the main control unit 108 . The main control unit 108 is connected to the vacuum gate of the main MOSFET 206. The source of the main MOSFET 206 is connected to the first battery terminal 202A. The drain of the main MOSFET 206 is connected to the positive terminal 222A of the heater 106. The negative terminal 222B of the heater 106 is connected to the ground point 226.

The main control unit 108 applies a pulse-width modulation (PWM) signal to the vacuum gate of the main MOSFET 206. This signal switches more current from the first battery terminal 202A via PWM using the main MOSFET 206. This provides a PWM signal using the current from the first terminal 202A of the battery, to the positive terminal 222A of the heater. Thus, the main control unit 108 uses the main MOSFET 206 to provide PWM power output to the heater 106.

An additional first resistor 224 is connected between the positive terminal 222A of the heater and the negative terminal 222B of the heater for testing purposes when the capsule is not connected; this resistor is not essential to the operation of the device.

The first battery terminal 202A is also connected to the first capacitor 208A and the second capacitor 208B in parallel. The first capacitor 208A and the second capacitor 208B are connected to ground points 210A and 210B, respectively. In the example, capacitor 208A has a capacitance of 10uF and capacitor 208B has a capacitance of 100nF. The first capacitor 208A and the second capacitor 208B are decoupling capacitors that reduce high frequency voltage fluctuations on the power plane.

The second battery terminal 202B is connected to the second resistor 214. The second resistor 214 is connected to the vacuum gate of the main MOSFET 206 and to the vacuum gate of the second transistor, or the second MOSFET 218. In the example, the second resistor 214 has a resistance of 100 kΩ. The second resistor 214 is connected to the vacuum gate of the main MOSFET 206 via a diode 212. The diode 212 prevents logic high signals from the PWM signal from the main control unit 108 from reaching the second MOSFET 218. The second resistor 214 erraticly connects the battery terminal to the vacuum gate of the second MOS -transistor 218 such that at the time of power-up or when the microprocessor unit 108 is turned off, the second MOS transistor 218 is turned off. During the hover operation, the PWM input signal from the microprocessor unit 108 suppresses the voltage from the second resistor 214. The main MOSFET 206 and the second MOSFET 218 may be p-channel devices, with a logic high output when on

- 5 043023 the vacuum gate is supplied with a logic low input voltage.

The second resistor 214 is connected to the vacuum gate of the second MOSFET 218 via the node 228. The third capacitor 216 is connected between the node 228 and the ground point 230. In the example, the third capacitor has a capacitance of 100 nF. At steady state, when the device is not hovering, the PWM input from the microprocessor unit 108 to the main MOSFET 206 is high, which turns off the main MOSFET 206. The third capacitor 216 is charged through the second resistor 214, causing the vacuum gate voltage the second MOSFET 218 goes high, and the second MOSFET 218 turns off. That is, therefore, no current flows through resistors 220A and 220B. When the microprocessor unit 108 drives the vacuum gate signal of the main MOSFET 206 to a low level during PWM, the third capacitor 216 is discharged, thereby turning on the second MOSFET 218. When the PWM signal from the microprocessor unit 108 to the main MOSFET 206 is held in time of the measurement phase as described later, the time constant of the third capacitor 216 and the second resistor 214 is such that the second MOSFET 218 remains on during the entire measurement phase, allowing the resistance between the heater coil terminals 222A and 222B to be measured. After the hover operation is completed and the signal from the microprocessor unit 108 returns to the main MOSFET 206 in a steady high state, the third capacitor 216 is charged, turning off the second MOSFET 218.

The source of the second MOSFET 218 is connected to the third battery terminal 202C. The drain of the second MOSFET 218 is connected to the heater positive terminal 222A via a test resistor 220. In the example shown in FIG. 2, the test resistor 220 contains two resistors 220A and 220V connected in parallel. In the example, each of these resistors are 68 ohm resistors, giving a total resistance of 34 ohms. As a general rule, 68 ohm resistors are more affordable (with the required power class, package size, and tolerance) than 34 ohm resistors. Alternatively, the test resistor 220 may consist of only one resistor, such as a 34 ohm resistor. In the example, the value of the test resistance is stored in memory associated with and accessible by the control device. One skilled in the art will readily appreciate that other numbers and combinations of resistors, with different resistor values, may be used as needed.

The third battery terminal 202C, the second MOSFET 218, and the test resistor 220 form a subcircuit 232 for measuring the heating coil voltage.

Second battery terminal 202B supplies switching current to the vacuum gate of second MOSFET 218 to turn on subcircuit 232.

In FIG. 3 is a flow diagram of the method for controlling the heater 106 by the controller 104 described with reference to FIG. 2.

The main control unit 108 supplies the duty cycle PWM output power to the heating coil and measures parameters related to the heating coil in a series of execution cycles. In a separate calculation cycle that runs in parallel with the execution cycles, the main control unit calculates the updated power output with the updated duty cycle based on the measured parameters. In one example, the computational cycle(s) use separate processing functionality for the execution cycle(s) so as not to interfere with the execution cycle(s).

In the first execution cycle in step S301, the main control unit 108 applies the first output power to the heating coil for the first number of steps of the first execution cycle. The first output power corresponds to the first PWM output power having the first duty cycle. Each step corresponds to a predetermined time interval, eg 66.6 µs (or a step frequency of 15 kHz). In the example, the first PWM output is supplied for 100 stages.

Each stage may correspond to an integer number of PWM cycles, where the PWM cycle has an on period and an off period constituting a PWM cycle. In the example, each stage corresponds to one PWM cycle.

In step S302, the main control unit 108 turns off the first output, thereby turning off the heating coil, in the second number of steps of the first execution cycle. In the example, the second number of steps is one step.

In a second number of steps, the main control unit additionally sets the heating coil to high voltage and measures the battery voltage under load before turning off the heating coil. The heating coil is set to high voltage only for a short time, on the order of microseconds. This ensures that the battery is under load when measuring battery voltage under load.

In step S303, the main control unit 108 measures the first heating coil voltage in a third number of steps. In the example, the third number of stages is one stage.

The first heater coil voltage is measured using the heater subcircuit 232.

- 6 043023 coils. The heater coil subcircuit 232 is turned on by the discharge of the third capacitor 216 under the effect of a logic low PWM input of the MOSFET 206. A very small current is then passed through the test resistor 220 from the third battery terminal 202C to the positive terminal of the heater coil 222A. This allows a small, controlled potential to be applied to the heating coil 106 when the heating coil 106 is off (ie, not heating). This small, controlled potential allows the heater voltage to be measured while the battery 102 recovers from heating the heater coil 106. In the example, the power applied to the heater coil 106 during the heater coil voltage measurement is extremely small compared to the power applied to the heater coil during the first count. stages of the execution cycle when the heating coil 106 is heated.

In step S304, the main control unit suspends the first execution cycle or does not take any action in the first control cycle, and the heating coil is turned off for the fourth number of steps. In the example, the fourth number of stages is five stages.

A pause in step S304 between measuring the heater coil voltage in step S303 and measuring the no-load battery voltage in step S305 allows the no-load battery voltage to be measured separately from the heater coil voltage, so that the heater coil voltage is measured immediately after heating, giving the battery time to recover without applied heating load (i.e. in the unloading state) before measuring the battery voltage without load. This allows you to accurately measure both the voltage of the heating coil and the voltage of the battery without load.

In step S305, the main control unit measures the first no-load battery voltage in the fifth number of steps of the first execution cycle. In the example, the fifth number of steps is one step.

In general, if a new PWM output signal, i.e. the new duty cycle PWM output is available from a separate calculation cycle, as will be described later, the main control unit 108 updates the output power, in a fifth number of steps, for the next or subsequent cycle. The main control unit 108 then initiates a subsequent execution cycle following essentially the same steps as the first execution cycle, but using the updated power output. If a new PWM output signal is not available from a separate computing cycle, the main control unit 108 does not update the output power for the next cycle. The main control unit 108 then initiates a second execution cycle following essentially the same steps as the first execution cycle using the output power.

An example of the operations of each of the stages of the first execution cycle is presented in Table. 1.

Table 1

Stage number Operation 0-99 Application of the first power output to the heating coil 100 Switching off the first output power and thus switching off the heating coil, mi optionally setting the heating coil to high voltage and measuring the first battery voltage under load before switching off the heating coil 101 Measurement of the first voltage of the heating coil of the specified heating coil 102-105 Pause with heating coil off 106 Measurement of the first battery voltage without loading the specified battery

In the example of 66.6 µs per stage, with 107 stages, the execution cycle takes 7.13 ms to execute 107 stages.

One skilled in the art will readily appreciate that other numbers of stages and other time intervals for each stage may be used instead of the above examples, where applicable.

Parallel to the start of the execution cycles, the main control unit periodically starts the calculation cycle. For example, the main control unit starts a calculation cycle, checking for new or updated measurement data every 2 ms. If new measurement data is available from the execution cycle(s), the calculation cycle calculates the updated output power (i.e., the PWM output power with the updated duty cycle). If there is no new measurement data from the execution cycle(s), the calculation is not performed.

- 7 043023

The compute cycle is performed separately from the execution cycles, since calculations can take longer than one execution cycle and therefore may cause a heat-up delay if calculations are performed as part of the execution cycles.

The following description sets out how the calculation loop calculates the updated runtime using the parameters measured in the execution loop.

The compute loop computes the updated duty cycle, DCYCLE, as follows: _ ^target X ENABLE_PWM_MATCH

ecycle-j

Hoad where ITARGET is the target current (in milliamps) applied to the heating coil;

I _LOAD is the maximum available load current (in milliamps) calculated from the battery voltage under load and the heating coil resistance, limited by the battery current limit.

This calculation gives the number of microprocessor counter cycles that the output must be on per PWM cycle. ENABLE_PWM_MATCH is the value of an internal counter in the microprocessor corresponding to one PWM cycle period (for example, 66.6 µs). In the example, the microprocessor counter is running at 16 MHz, for which ENABLE_PWM_MATCH is 16 MHz x 66.6 µs = 1066.

In the example, the load current, I _LOAD , is calculated as:

, _ ^ONLOAD

LOAD /р I p λ

V ^K COIL + ^K SERIES) where V _ONLOAD is the battery voltage at load, measured in the second number of stages of the execution cycle with the heating coil set to high voltage.

The voltage of the battery under load corresponds to the voltage of the battery under load, i.e. in a state in which a heating load is applied. When a potential divider formed from two resistors R _A and R _B is used to scale the battery voltage to a level suitable for the microcontroller's A/D converter, and the voltage read by the A/D converter is V _ADC , this can be expressed as:

_TL _ ^adc ^x (Ra + Kv) ^V ONLOAD - η ^Κ Α

In the example, the resistance R _A may be 1.5 kΩ and R _B may be 2 kΩ.

To set (R _COIL + RSERIES), the coil voltage (V _COIL ) on COIL+ 222A and COIL- 222B is measured. (R _coil + RSERIES) is the resistance of the heating coil measured on COIL+ 222A and COIL- 222B, including the series resistance of the contacts that are in series with the heating coil, but which contribute to the measured voltage V _COIL , as stored in the electronics of the material capsule, generating steam. Series resistance is not expected to change significantly with temperature, and is measured during manufacture and stored in the capsule's electronic circuitry. In the example (R _COIL + R _series ) is calculated as:

, X RtFST ίη ι р λ _ ^J

V ^K COIL + ^SERIES) - _{I7 τζ V} ^{OFFLOAD - V} COIL connector, etc.) and is selected to obtain a suitable pin voltage considering the range of R _B that will occur, the gain of the amplifier (not shown in FIG. 2), and the range of the ADC of microcontroller 108. In the example, test resistor 220 has a resistance of 34 ohm;

V _OFFLOAD is the battery voltage without load, measured in the fifth number of stages of the execution cycle. The no-load battery voltage corresponds to the battery voltage in the no-load state, i.e. in a state in which no heating load is applied. This is measured using the same potential divider as V _ONLOAD , but in an unloaded state;

V _COIL is the heater coil voltage measured in a third number of steps by the heater coil sensing subcircuit 232.

An amplifier circuit (not shown in FIG. 2) applies a gain and an offset to this voltage before it is measured by the ADC microcontroller. In the example, the voltage across the heating coil can be measured as a function of the voltage at the microcontroller pin (V _PIN ):

VpiN ⁼ VcOIL X M + C so _ίΖ _ VpiN “ C ^V COIL - _m where M is the gain of the amplifier, calculated as:

AMP CAL M

M =----------=---=-------AMP CAL M SCALE FACTOR

- 8 043023 and C offset correction value is calculated as:

_ ^AMP_CAL_C " AMP_CAL_C_SCALE-FACTOR where AMP_CAL_M is the value measured during device calibration for the amplifier circuit gain (not shown in FIG. 2);

AMP_CAL_M_SCALE_FACTOR is used to facilitate integer arithmetic instead of floating point numbers.

In the example, AMP_CAL_M_SCALE_FACTOR may have a constant value of 1000. AMP_CAL_C is the value measured during device calibration for the amplifier circuit gain (not shown in FIG. 2). AMP_CAL_C_SCALE_FACTOR is used to facilitate integer arithmetic instead of floating point numbers. In the example, AMP_CAL_C_SCALE_FACTOR can have a constant value of 1000000.

The target current supplied to the heating coil, I _T a _RGET , is calculated as:

^TARGET - (?GAIN ^X ^ERROr) + (J GAIN ^X ^SUm) where I _TargeT is the estimated current that should be the target (limited by the maximum allowable current);

I _GAIN and P _GAIN are constants;

I _GAIN is the scaling factor used for the integral part of the PIM control system (proportional, integral, derivative);

P _GAIN is the proportional gain for the controller making the measurement.

In the example, I _GAIN has a value of 2500 and P _GAIN has a value of 250. I _SUM corresponds to the summation integral term used in calculating the PID. A PI control algorithm is used to calculate the required current to reduce the temperature error based on the measured coil resistance and battery voltage. The algorithm is executed as part of a computational loop and does not start measurements directly; measurements are run separately in an execution cycle. TERROR is the difference between the target heating coil temperature, T _target , and the measured coil temperature T _coil , thus:

Terror-T _target -T _C0IL

The coil temperature, T _coil , is determined based on the resistance of the heating coil, R _COIL , as measured on the heating coil measurement subcircuit 232, where:

( ^COIL ¹ coil — In ' ^K REFCOIL “ + T _REE where R _refcoil is the coil resistance reference value stored in the electronics of the vapor generating material capsule;

the constant α is the drag coefficient, a property of the wire used for the coil. In the example, α may have a value of 0.004130;

T _ref is a reference temperature stored as a constant in the microprocessor code corresponding to R _refcoil . In the example TREF is set to 25°C.

If the target current is calculated as being in excess of the maximum available current allowed to be drawn from the battery, then the effective temperature error that would result in the calculation of the maximum available current is used to increase the value of I _SUM . Otherwise, the actual temperature error is used as:

, __________Terror_________

SUM - _TEM p_ _ERR0 R_DlVIDER where TEMP_ERROR_DIVIDER is the I _GAIN sensitivity to temperature error. In the example, TEMP_ERROR_DIVIDER has a value of 600.

In FIG. 4 is a timing diagram of execution of execution cycles and computation cycles relative to each other in accordance with the example.

In FIG. Figures 5 and 6 respectively show block diagrams of the processes involved in the execution and computational cycles.

The first execution cycle 401 is performed as described with reference to FIG. 2. In step S501, in the first execution cycle 401, the main control unit applies the first output power to the heating coil for the first number of steps 401-1. In step S502, in the first execution cycle 401, the main control unit sets the heating coil to high voltage and measures the first battery voltage under load before turning off the heating coil, turning off the first output for the second number of steps 401-2. Setting the heater to high voltage refers to setting the input line from the main control unit (or microprocessor unit) 108 to turn on the main MOSFET 206, and not to any specific temperature target. This occurs within a very short period of time (on the order of microseconds) and therefore has little heating effect. In step S503, in the first execution cycle 401, the main control unit measures the first heating coil voltage in the third number of steps 401-3. In step S504, in the first execution cycle 401, the main control unit pauses with the heating coil off for the fourth number of steps 401-4. In step S505, in the first execution cycle 401, the main control unit measures the first battery voltage without battery load in the fifth number of steps 401-5. It should be noted that in FIG. 4, the number of stages in each execution cycle is shown not to scale, but at the same distance from each other for ease of perception.

Simultaneously with the implementation of the first execution cycle, the main control unit performs periodic steps 451a, 451b, 451c, 451d tracking to obtain new measurement data for the computing cycle. As shown in FIG. 6, the calculation loop checks whether new measurement data is available in step S601, if available, the calculation loop proceeds to step S602 and calculates an updated output power. In step S603, the main control unit makes the updated power output available for the execution cycle. In the example, the updated output power is calculated as described earlier. If new measurement data is not available, the process returns to step S601 and checks again whether new measurement data is available from the execution cycle. This process is repeated until new measurement data is available and the process may proceed to step S602. In the example, the process loops at step S601 to check for new measurement data every 2 ms. This interval proved to be advantageous, since the main control unit also handles other tasks, such as a Bluetooth connection. For example, if the interval in which new measurement data is checked was significantly longer, and these other tasks delayed the computational cycle, and it missed its time interval, then a significant period of time will pass until new measured values are available; this can cause significant timing issues and inconsistencies in data processing times. Performing a second cycle every 2 ms, for example, provides a maximum of 2 ms of delay or jitter. This has been found to be an acceptable period of time without unduly increasing the load on the main control unit or microprocessor.

Returning to the first execution cycle, in the fifth number of steps 401-5 of the first execution cycle 401, in step S506, the main control unit checks whether an updated output power is available from the calculation cycle. If the updated output power is available, the process proceeds to step S507, and the output power is updated for the next execution in the fifth number of steps. However, during the first execution cycle 401, the measurement data was not available for the calculation cycle because the measurements are still in progress. As a result, no calculations have been made yet. As a consequence, the main control unit does not update the output power in the fifth number of steps 401-5 of the first execution cycle 401 for the next execution cycle. Instead, the first output is used for the second execution cycle 402, and the process returns to step S501 for the second execution cycle 402. That is, after the first execution cycle 401, the second execution cycle 402 is executed using the first output.

In step S501, in the second execution cycle 402, the main control unit applies the first output power to the heating coil for the first number of steps 402-1. At step S502, in the second execution cycle 402, the main control unit sets the heating coil to high voltage and measures the second battery voltage under load before turning off the heating coil, turning off the first output for the second number of steps 402-2. In step S503, in the second execution cycle 402, the main control unit measures the second heating coil voltage of the heating coil in a third number of steps 402-3. At step S504 in the second execution cycle 402, the main control unit pauses with the heating coil off for the fourth number of steps 402-4. In step S505, in the second execution cycle 402, the main control unit measures the second battery voltage with no battery load in the fifth number of steps 402-5.

During the implementation of the second execution cycle, the main control unit determines in step S601 that new measurement data is available for the calculation cycle in step 451e tracking, ie. in the first stage of tracking, which occurs after the completion of the first execution cycle. Then the process of FIG. 6 proceeds to step S602, and the main control unit executes the first calculation cycle 451e using the measurement data.

In the example of FIG. 4, the first computational cycle takes significantly longer than each execution cycle. Thus, at the end of the second execution cycle 402, the first calculation cycle 451e is still in progress and the updated power output is not ready. That is, when the second execution cycle 402 reaches step S506 in the fifth number of steps 402-5 of the second execution cycle, the updated output power is not available from the calculation cycle, and therefore the process returns to step S501 for the third execution cycle 403. Since at the end of the second cycle 402 the updated output power is not ready, the main control unit performs the third execution cycle 403 using the first output power after the second execution cycle 402.

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In step S501 in the third execution cycle 403, the main control unit applies the first output power to the heating coil for the first number of steps 403-1. At step S502 in the third execution cycle 403, the main control unit sets the heating coil to high voltage and measures the third battery voltage under load before turning off the heating coil, turning off the first output power for the second number of steps 403-2. In step S503, in the third execution cycle 403, the main control unit measures the third heating coil voltage of the heating coil in the third number of steps 403-3. At step S504 in the third execution cycle 403, the main control unit pauses with the heating coil turned off for the fourth number of steps 403-4. In step S505 in the third execution cycle 403, the main control unit measures the third battery voltage without battery load in the fifth number of steps 403-5.

When the third execution cycle 403 reaches the fifth number of steps 403-5, the main control unit 108 determines in step S506 that the calculation cycle 451e has been completed and that the updated output power has been withdrawn from the calculation cycle in step S603. Thus, the execution cycle process proceeds to step S506, and the main control unit 108 updates the first output power to the updated output power in the fifth number of steps 403-5 of the third execution cycle 403.

Then, the execution cycle process returns to step S501 for the next (or fourth) execution cycle. In step S501, the main control unit 108 executes the fourth execution cycle 404 using the updated output power for the first number of steps of the fourth execution cycle 404-1. At step S502 in the fourth execution cycle 404, the main control unit 108 then sets the heating coil to high voltage and measures the fourth battery voltage under load before turning off the heating coil, turning off the updated output for the second number of steps 404-2. In step S503, in the fourth execution cycle 404, the main control unit measures the fourth heating coil voltage of the heating coil in the third number of steps 404-3. At step S504 in the fourth execution cycle 404, the main control unit pauses with the heating coil off for the fourth number of steps 404-4. In step S505, in the fourth execution cycle 404, the main control unit measures the fourth battery voltage without battery load in the fifth number of steps 404-5.

After the completion of the first calculation cycle in step S603, the calculation cycle process returns to step S601 and checks again whether new measurement data is available from the execution cycle. This process is repeated until new measurement data is available and the process may proceed to step S602.

If the updated measurement data is not yet available, for example, because the fourth execution cycle 404 using the updated output power has not yet been completed, the main control unit 108 performs periodic tracking steps 452a, 452b in step S601 for new measurement data. The main control unit 108 determines that the new measurement data is available for the calculation cycle at the tracking step 452c, i. e. in the first tracking step that occurs after completion of the fourth execution cycle 404. Then, the calculation cycle process proceeds to step S602 for the second calculation cycle 452c, and the main control unit 108 executes the second calculation cycle 452c using the new measurement data.

The process is then repeated, thus updating the output power when an updated output power is available, and calculating the updated output power when new measurement data is available.

One of ordinary skill in the art will readily appreciate that the first computational cycle may take less or more time than the previous example, and that the first computational cycle may be completed during the second execution cycle such that the power output is updated in the second execution cycle for the third execution cycle, or that the computing cycle can be completed during the third or later execution cycle such that the power output is updated in the fourth or later execution cycle. The same applies to when computing cycles are executed in terms of the length and number of execution cycles, depending on the conditions.

The main control unit processing steps described herein may be stored in a permanent computer-readable medium or data store associated with the main control unit. The computer-readable storage medium may include non-volatile media and volatile media. Volatile media may include, but are not limited to, semiconductor memories and dynamic memories. Non-volatile media may include, among others, optical discs and magnetic discs.

One skilled in the art will readily appreciate that the above embodiments in the above description are not restrictive; features of each embodiment may be used in other embodiments as appropriate.

Claims (16)

1. A control device for an aerosol generating device, wherein the control device comprises a main control unit and is configured to be connected to a battery and a heating coil, wherein the main control unit is configured to perform one or more execution cycles, with the first execution cycle of one or more executive cycles provides: applying the first power output to the heating coil for the first number of steps of the first execution cycle; turning off the first output power and thereby turning off the heating coil in a second number of steps following the first number of steps of the first execution cycle; measuring a first heating coil voltage of said heating coil in a third number of steps, following a second number of steps, of a first execution cycle with an output power less than the first output power supplied to the heating coil; suspending with the heating coil off for the fourth number of steps following the third number of steps of the first execution cycle; and measuring the first no-load battery voltage in the fifth number of steps following the fourth number of steps of the first execution cycle, the no-load battery voltage corresponding to the no-load state of the battery in which no heating load is applied; wherein each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period; and wherein the main control unit is further configured to calculate the updated power output based on the first heating coil voltage and the first no-load battery voltage. 2. The control device according to claim 1, characterized in that the main control unit is further configured to apply the updated power output to the heating coil in a subsequent execution cycle that follows the first execution cycle. 3. The control device according to any one of the preceding claims, characterized in that the main control unit is further configured to calculate the updated power output based on the first heating coil voltage and the first no-load battery voltage in a calculation cycle separate from one or more execution cycles. 4. The control device according to claim 3, characterized in that the main control unit is configured to perform a calculation cycle and one or more execution cycles using separate processing functionality. 5. The control device according to claim 3 or 4, characterized in that the main control unit is additionally configured to perform a second execution cycle, wherein the first execution cycle is offset from the subsequent execution cycle by at least a second execution cycle, and where the second execution cycle provides for the application of the first output power to the heating coil for the first number of stages of the second execution cycle; and wherein the main control unit performs the calculation cycle at least partially in parallel with the second execution cycle. 6. The control device according to any one of claims 3 to 5, characterized in that the main control unit is additionally configured to perform a third execution cycle between the first execution cycle and the subsequent execution cycle, while the third execution cycle provides for: applying the first output to the heating coil for the first number of steps of the third execution cycle; and updating the first output to the updated output in response to determining that the updated output is available from the computation cycle. 7. A control device according to any one of the preceding claims, characterized in that each power output is a pulse width modulated output signal with an associated duty cycle. 8. The control device according to any of the preceding claims, characterized in that the main control unit is configured to calculate the temperature of the heating coil based on the resistance of the heating coil, and is further configured to calculate the updated power output based on the difference between the calculated temperature of the heating coil and the target temperature of the heating coil. coils. 9. The control device according to claim 8, characterized in that it additionally contains a meter - 12 043023 heating coil subcircuit, wherein the heating coil measuring subcircuit comprises a battery terminal connected to the heating coil and a test resistor located therebetween. 10. A control device according to claim 9, wherein the heating coil sensing subcircuit is configured to apply less power than the first power output to the heating coil to measure the first heating coil voltage. 11. The control device according to claim 9 or 10, characterized in that the main control unit is configured to calculate the resistance of the heating coil based on the first voltage of the heating coil, the resistance of the test resistor and the first battery voltage without load. 12. A control device according to any one of the preceding claims, characterized in that the main control unit is further configured to, in a second number of steps, set the heating coil to high voltage and measure the first battery voltage under load before turning off the heating coil. 13. A control device according to any one of the preceding claims, further comprising a first transistor, wherein the pulse width modulation input signal switches the first transistor to provide a pulse width modulation output signal to the heating coil. 14. An aerosol generating device comprising a control device according to any one of the preceding claims. 15. The method of operation of the control device of the device that generates an aerosol, while the method includes in the first execution cycle: applying the first power output to the heating coil for the first number of steps of the first execution cycle; turning off the first power output and thereby turning off the heating coil in a second number of steps following the first number of steps of the first execution cycle; measuring a first heating coil voltage of said heating coil in a third number of steps, following a second number of steps, of a first execution cycle with an output power less than the first output power supplied to the heating coil; suspending with the heating coil off for the fourth number of steps following the third number of steps of the first execution cycle; and measuring the first no-load battery voltage in the fifth number of steps following the fourth number of steps of the first execution cycle, the no-load battery voltage corresponding to the no-load state of the battery in which no heating load is applied; wherein each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period; and wherein the method further includes calculating the updated power output based on the first heating coil voltage and the first no-load battery voltage. 16. A non-volatile computer-readable medium that stores instructions that, when executed by one or more processors, cause the one or more processors to execute in the first execution cycle: applying the first power output to the heating coil for the first number of steps of the first execution cycle; turning off the first output power and thereby turning off the heating coil in a second number of steps following the first number of steps of the first execution cycle; measuring a first heating coil voltage of said heating coil in a third number of steps, following a second number of steps, of a first execution cycle with an output power less than the first output power supplied to the heating coil; suspending with the heater coil off for the fourth number of steps following the third number of steps of the first execution cycle; and measuring a first off-load battery voltage in a fifth number of steps following the fourth number of steps of the first execution cycle, the off-load battery voltage corresponding to an off-load state of the battery in which no heating load is applied; wherein each step in the first number of steps, the second number of steps, the third number of steps, the fourth number of steps, and the fifth number of steps corresponds to a predetermined time period; and further includes calculating an updated power output based on the first heating coil voltage and the first no-load battery voltage.