WO2024013774A1

WO2024013774A1 - Adaptive energy converter with variable duty cycle and frequency modulation

Info

Publication number: WO2024013774A1
Application number: PCT/IT2023/050162
Authority: WO
Inventors: Rocco BISCAGLIA; Giuseppe TANCREDI
Original assignee: Cloudwise S.R.L.
Priority date: 2022-07-13
Filing date: 2023-07-13
Publication date: 2024-01-18

Abstract

The proposed invention relates to an adaptive energy converter with variable duty cycle and frequency modulation. Said converter is capable of generating a single signal in which frequency and duty-cycle vary simultaneously, as required, due to a microcontroller that dynamically sets and varies these parameters according to the input signals. These output values (frequency and duty cycle) are preloaded and mapped to a memory. The adaptive energy converter with variable duty cycle and frequency modulation is therefore characterized by a microcontroller (101) that processes external signals to dynamically and simultaneously modify the parameters (duty cycle, frequency) for conversion of primary energy into secondary energy. These parameters are optimised for the best possible operation of a load or user. The control unit receives external inputs that are processed by the device in order to generate the correct output modulated in frequency (f) and pulse width (pwm). Having defined p(n) the current working point at the instant n characterized by a certain frequency f=f(n) and characterized by a certain pulse width pwm= m(n), this differs, due to the effect of the control unit, from the previous working point p(n-1) to the instant n-1; said working point being characterized by a different frequency f(n-1) and by a different pulse amplitude m(n-1). The system then dynamically changes said working point from p(n-1) to p(n) which is transmitted from the control unit to the switches of the converter driving the conversion of primary energy into secondary energy.

Description

ADAPTIVE ENERGY CONVERTER WITH VARIABLE DUTY CYCLE AND FREQUENCY MODULATION

Technical field

The object of the invention relates to the field of energy management through electronic devices and, more particularly, concerns an adaptive energy converter with variable duty cycle and frequency modulation; said converter being able to modify in an adaptive way its working point, i.e., the frequency and the pulse width (or duty cycle) of a modulating signal adapted for driving the power element used to transform primary energy into secondary energy.

State of the Art

Various techniques and modes for converting electric energy based on the control of power elements are known in the state of the art. In particular, different modes are known for driving certain power elements used to supply energy to a load through appropriate signal modulations. An elementary type of modulation is ON/OFF modulation in which a switching arrangement (relay, transistor, MOSFET, and electro-mechanical devices) is always open or always closed for very long periods of time in relation to electronic applications. In systems of this type a switch element changes state when certain events occur, while the opening and closing times of said element can be variable and controlled in order to obtain the desired and useful electrical energy supply to a load.

It is an elementary modulation but already very useful since the energy needed to open and close the “switch” is very limited and related to the technical time necessary for the device used to make the state change and to the voltage and current values at the moment of switching.

A more advanced mode, very well-known and applied in many fields of electronics, is the pulse modulation called PWM, acronym for Pulse Width Modulation. This technique is often used in power electronics, for the realization of devices such as by way of example and not limited to: current and voltage supplies, and DC-AC inverters, i.e., devices where such PWM modulation is exploited to drive a power element and generate, starting from an energy source in the form of a continuous wave, an alternating current voltage (AC, true sinusoidal wave inverter). Note how, according to said PWM technique, the frequency of the pulses is fixed and, in general, also the width of the pulses. A controller, in fact, acting on fast switching devices, such as by way of example and not limitation: MOSFETs, transistors and functionally equivalent power devices, can terminate these pulses at predetermined times, thus acting on their duration, and having as a final consequence the desired pulse modulation.

The energy that manages an energy converter such as PWM switching can be very small in the case of signal management, while in the case of energy management the energy required can be much greater.

The disadvantage of energy converters based on the technique of PWM modulation is in fact the fixed frequency: the dedicated circuits can in fact vary (and therefore adapt) only by varying the duration over time, i.e., the pulse width, as can be intuited from the acronym PWM.

This structural limitation of the PWM technique results in a disadvantage and leads to limiting the number of applications and their operating range.

Furthermore, energy converters based on this type of modulation typically require a magnetic energy storage component, be it an inductor or a transformer in the case of high frequency, and at the same time numerous other components such as capacitors (electrolytic) and the (already mentioned) switching devices. Further requiring, diodes, MOSFETs, transistors.

Finally, PWM type energy converters mainly have two types of operation called COM and DCM, where COM stands for Continuous Conduction Mode and DCM stands for Discontinuous Conduction Mode. In Continuous operation the current in the magnetic component is never interrupted during the cycle time or period, which is fixed and depends on the working frequency. The output voltage and current depend with a simple and easily calculable mathematical relationship on the parameters of the energy supplied in input, which is very important from the point of view of the control circuit. In Discontinuous operation, however, the current in the magnetic component is interrupted before the end of the period and then before the beginning of the next cycle. In this second case, the mathematical relationship, which links the output voltage and current parameters with those of the input voltage and current, becomes very complex and no longer depends only on these parameters. For example, the value of the inductance of the magnetic component employed takes on a significant role and since said components are affected by constructive tolerance (which, moreover, varies further with the variation of other parameters, temperature, frequency, etc.) it becomes difficult to calculate and obtain the values desired by the converter mathematically, a priori. What is more, given this difficulty, current interruptions can occur, which in turn can lead to malfunctions, instability and failures in the application. Intuitively, one only has to think of what can happen if one interrupts the current in a high-power transformer of a push-pull converter for a few microseconds and then reactivates it.

Since the early days of electronics, the use of specific chips that perform PWM modulation is still widespread (see for example US7079758B2). Almost all microcontrollers have modules called CCP, an acronym for Compare Capture PWM, while others have multiple CCP modules and also ECCP modules, where “E=Enhanced”, that is, equipped with better management through software in the module itself. The module is completely autonomous, that is, once the setting parameters are received, it works independently of the development of the program and interacts with voltage comparators that work on analogue voltage levels.

For example, the integrated 555 (nicknamed time machine), still built by many electronic companies and available on the market since the early 1970s, is nothing more than a chip that, with few external components, can generate an astable square waveform, that is, fixed frequency pulses, while another 555, used as a ‘trigger’, can truncate the pulse when necessary, that is, modulate it, when an electrical event to be controlled occurs, typically an over-range of current, voltage, both, over-range of power. This modulation is also designed to have power supplies with small size but medium power (hundreds of W) for use on portable equipment. An example of this are the first computers released on the market by Olivetti, IBM and Sharp. The internal power supply, multi-voltage, powered the circuits at 5V / tens of Ampere (logic part). Even in printers (characterized by positive and negative voltages typically of +/- 12V), the same principle was applied to advance the carriage in both directions. Instead, it did not power the monitors, which made use of the technology already known from cathode-ray televisions with AC power. These power supplies still exist and are produced in standard size and performance, little has changed since their first appearance on the market.

The limit of the PWM technique is the need for continuous CCM operation, which, however, implies a limitation in the operating range of the converter.

Finally, there are other modulation techniques used to control the power element of energy converters, in particular the so-called PFM (Pulse Frequency Modulation) technique in which the modulating signal causes the pulse rate to vary. Unlike PWM, where the amplitude of square pulses is varied at a constant frequency, PFM fixes the amplitude of square pulses by varying the frequency. In other words, the frequency of the pulse train is varied according to the instantaneous amplitude of the modulating signal at sampling intervals. The amplitude and width of the pulses are kept constant.

The PFM technique is poorly employed in energy converters as it involves increasing the driving frequency of static power switches as it is characterized by considerably higher switching losses than those typical for the PWM technique.

As in the case of the 555 circuit (PWM modulation perl) there are electronic e-modules able to realize PFM modulation, what is absent in the literature and in the art is an electronic device able to simultaneously combine multiple modulation techniques (e.g., PWM and PFM) overcoming the criticalities and adding the advantages.

In fact, in order to transfer energy better and more uniformly and continuously than the aforementioned PWM and PFM conversion systems, it would be useful to have a system that allows both the frequency and the duty cycle of a modulating signal to be controlled/adjusted simultaneously and used for driving the power element of an energy converter.

There exist in the state of the art patents concerning energy converters that in their operation employ signals that by their intrinsic characteristics include signals with modulation in amplitude and frequency; these patents are for example:

• Patent LIS2015326123 “DC/DC converter, control circuit and control method thereof, and electronic apparatus” (Rohm Co Ltd, Fukushima Shun [JP] et Al; 12 November 2015)

• US2018 “Control method for improving dynamic response of switch power” (Univ Southeast [CN], Xu Shen [CN] et Al, 16 August 2018)

The converters referred to in the aforementioned patents use control signals in their operation to detect errors and/or anomalies that exploit both modulations (PWM and PFM), however:

• do not drive the power element of the converter;

• do not vary the working point of said signal (frequency and duty cycle).

I use a dynamically and adaptively constructed composite signal (freq, pwm) with dynamically variable working point to drive the power element

Summary disclosure of the invention

According to the present invention, an adaptive energy converter with variable duty cycle and frequency modulation is realized, which effectively solves the problems that characterize the traditional PWM and PFM systems. In particular, an energy converter is presented in which the power element (transistor, MOSFET or other functionally equivalent elements) is suitably used to deliver energy to a load through a mixed modulating signal and with a working point that is variable in amplitude and frequency. Said mixed modulating signal is dynamically adapted in its fundamental parameters (frequency / duty cycle) to expediently suit both the needs of the load connected in output and with respect to the energy supplied and available in input. Said mixed modulation signal is controllable by means of a control unit with a microcontroller system or functionally equivalent system that allows dynamically and adaptively modifying the working point (frequency and duty cycle); said working point is controlled and updated by means of an appropriate memory and management algorithm that allows dynamically adapting the working conditions and changing said working point in order to achieve the best and appropriate working conditions of the energy converter and depending on the conditions of use. In other words, the object of the invention is to overcome the limitations of the PWM technique related to the fixed frequency, also introducing into said technique the simultaneous variation of the working frequency. Said simultaneous and adaptive variations of the working point in terms of frequency and duty cycle allow a better performance of the energy converter with respect to the conditions of use, in particular of the primary energy available and of the load to be supplied.

Brief description of the accompanying drawings

The invention will be described below in at least one preferred exemplary and non-limiting embodiment with the aid of the accompanying figures, in which:

FIGURE 1 graphically illustrates the components necessary for the realization of a preferred application: the control unit 100, the processor 101 , a memory 200 (for example of the EEPROM type, an energy meter 500 and an energy converter 500;

FIGURE 2 and FIGURE 3 illustrate through a diagram the operation of a DITHER routine applied to MPPT. The routine allows the maximum power point MPPT to be tracked. It is a routine similar to those called P&O (perturb and observe). The following notations are used in these figures:

D.C. = duty cycle = pulse width in the period. PWM = pulse width modulation. Increasing direction = indicates whether the D.C. is increasing or decreasing. PWM D.C. max and min = the maximum pulse width and the minimum that the hardware can support. Set increase direction = set D.C. increasing. Clear increase direction = set D.C. decreasing. Figure 3 also shows how the flow diagram of the DITHER routine is modified to obtain MPPT at variable D.C. and frequency for a power supply; FIGURE 4 illustrates a flow diagram for charging and discharging a load, by way of example and without limitation, consisting of a battery pack.

FIGURES 5 and 6 show graphs relating to the following phenomenon: an energy converter, of any type, consisting of a magnetic component with an inductance of, for example, 100 uH, and a maximum continuous rate current of 10A.

FIGURE 7 illustrates an exemplary circuit diagram of the converter according to the proposed invention.

FIGURE 8 illustrates a typical control signal according to the proposed invention.

Optimal method for implementing the invention

The proposed invention relates to an adaptive energy converter with variable duty cycle and frequency modulation. Said converter is capable of generating a single signal in which frequency and duty-cycle vary simultaneously, as required, due to a microcontroller that dynamically sets and varies these parameters according to the input signals. These output values (frequency and duty cycle) are preloaded and mapped to a memory. The adaptive energy converter with variable duty cycle and frequency modulation is therefore characterized by a microcontroller (101) that processes external signals to dynamically and simultaneously modify the parameters (duty cycle, frequency) for conversion of primary energy into secondary energy. These parameters are optimised for the best possible operation of a load or user. The control unit receives external inputs that are processed by the device in order to generate the correct output modulated in frequency (f) and pulse width (pwm). Having defined p(n) the current working point at the instant n characterized by a certain frequency f=f(n) and characterized by a certain pulse width pwm= m(n), this differs, due to the effect of the control unit, from the previous working point p(n-1) to the instant n-1 ; said working point being characterized by a different frequency f(n-1) and by a different pulse amplitude m(n-1). The system then dynamically changes said working point from p(n-1) to p(n); said working point p(n) being transmitted from the control unit to the switches of the converter and driving the conversion of primary energy into secondary energy.

The field of application to which we will refer in the following implementation example is energy management. In particular, an example of application in the field of energy storage in battery packs is provided. As an introduction to the present invention, we refer to the description of Fig. 5 and Fig. 6 which report examples in the use of the standard PWM methodologies described above i.e., CCM and DCM. By replacing this approach with the mixed system comprising both the PWM and PFM modulations referred to in the proposed invention one can choose/fix an initial working point characterized by a certain frequency and work up to the limit of the DCM with the PWM modulation, then one can vary the frequency and exploit the entire PWM modulation field and so on. The proposed invention thus allows acting simultaneously on both the parameters of frequency (f) and pulse width (pwm) i.e., by varying both the pulse width and the pulse frequency. This makes it possible to obtain hundreds of working points depending on the hardware used, and thus finely vary the sensitivity even using basic 8bit controllers as hardware. The working frequency varies according to an appropriate management program with preset data recorded in an appropriate memory and dependent on the oscillator on board the controller or, possibly, on external clock oscillators to cover multiple frequency ranges.

By having this wide choice of working point, operating under low-frequency conditions, the switching losses (number of switch openings and closings) of a typical converter decrease, on the other hand the ripple on the output voltage increases as the output capacitor that typically characterises energy converters is charged at long time intervals (the capacitance value can be increased). Subsequently, and under these conditions, high-value inductances must also be used.

If working at high frequencies, the switching losses increase, the switches must be properly selected (fast switches), on the other hand the voltage and current ripples decrease, small value inductances and filter capacity can be used. If the application allows it, the proposed system can also work in an extended frequency range and pulse width.

For the practical realization of the mixed technique based on PWF and PFM according to the invention, the presence of a microcontroller or microprocessor control unit is necessary. In fact, the double modulation is obtained with a program running on said control unit.

The program code of said control unit is made according to the application and the hardware to be managed. The code must in fact implement the reference algorithm or routine for all the repetitive operations that must be done for the correct functioning of the circuitry.

The hardware that acts as an actuator of the code is generally an energy converter or a power supply with variable or constant voltage or current, of the most generic type. The control unit checks the operating parameters and, in particular, the working point and stabilizes/updates them according to the objective to be achieved.

In one embodiment of the invention the described system can be managed by creating a map of the working points on which the hardware must work. In particular, the values of voltages, currents, frequencies and temperatures are established, both in input and output.

This map can reside in a physical memory, for example an EEPROM, and the controller of the control unit automatically detects the input (primary energy available) and output (load to be supplied) parameters, and decides and dynamically adapts the working point (frequency and duty cycle) on which the converter must work.

Alternatively, the working point may be of the ‘running’ type. If the calculations to be made are not complex, in fact, the controller can detect, during the execution of the program, the conditions outside the hardware and from time to time establish (calculate) the next working point.

As a detail of the present invention, we will now describe, from a qualitative point of view, what has been said and the improvements and advantages to be gained by applying this type of modulation to an energy converter which, starting from an input energy source, charges a load consisting of a battery pack or even a single battery. The converter can be of any type: buck, boost, interleaved boost, and others. The topology depends on the input and output energy parameters. In the memory of the control unit, many work points are implemented, each characterized by a working frequency and a duty-cycle = pulse width (W), the pack voltage and other input and output parameters are also read in ADC and the reference data entered in the program is compared.

From the operational point of view, the control unit reads the parameters external to the hardware and identifies the work starting point. The load to be supplied, in this case a battery pack, begins to charge but, as less current is absorbed, hence there is the need to change the working point that is to vary both the frequency and the duty-cycle, i.e., to carry out a joint PWM PFM modulation. The frequency variation makes it possible to work with progressively lower currents in order to avoid DCM conditions. At the same time the duty-cycle is adjusted to compensate for the increase of the input voltage to the new (increased) voltage of the load/battery pack. Thanks to this device, it is possible to work up to very low currents compatible with the current values of the “float” state of the batteries. Batteries can remain in this state indefinitely without being damaged, indeed the (small) float current compensates for selfdischarge. This fact is very useful in the case of lead-acid batteries which, once charged, tend to discharge and become damaged due to the phenomenon of “sulphation”.

Additionally, thanks to the proposed solution of the PWM/PFM type, it is possible to change the working point depending on the status of the battery charge/battery pack and manage both the charge and the discharge in all phases. For example, in the discharging phase it is possible to move the working point to lower frequencies so as to allow greater switching efficiency. In fact, the energy absorbed and to be dissipated for the switches is lower, and in general the wear of all the hardware is lower. Finally, even in the discharge phase, by controlling (modulating) the frequency, the DCM, that is the operation of the converter in a discontinuous mode, is avoided.

A further advantage is the possibility of exploiting this modulation to facilitate the management of the so-called MPPT (Maximum Point Power Tracker) in equipment that manages variable energy sources, that is, typically renewable sources such as photovoltaic and wind. Under these circumstances and with the possibility of changing both frequency and pulse amplitude, large but also very small amounts of energy (at the maximum frequency limit) can be intercepted, resulting in a very wide operating range of the converter in CCM (practically never switching off). To obtain an MPPT, the hardware must be forced to absorb the maximum input energy (as described in the flowchart attachments) by imposing duty-cycle and increasing frequency working points. Currently, when the input energy parameters go out of range the equipment is turned off. Example of photovoltaic energy when the minimum tripping voltage of the DC-AC inverter is not achieved.

With reference to the accompanying drawings and in particular Fig 5 and Fig 6, an example is given where the decision is taken to work with a PWM technique at a frequency of 100 KHz. The period is therefore equal to 10usec. A duty-cycle of 50% is chosen. The input voltage of the converter is continuous and equal to 50V.

These parameters:

• allow a step-up (or boost) converter to double the input voltage > 100V output voltage, operating in CCM mode. (Fig. 5 principle diagram);

• allow a step-down converter (or buck) to halve the input voltage > 25V output voltage, CCM mode operation. (Fig. 6 principle diagram).

In both cases the time when the switching is closed is equal to 5usec this is the t_on, and open for another 5usec this is the t_off. The cycle repeats itself according to these timeframes. The maximum current that the application can manage is equal to the current of inductance rates and obviously also depends on the characteristics of the switches used by the converter, the change in current in the case of input voltages assumed as continuous can be calculated with the formula LDI= Vdton from which DI = deltal = 2.5 A (Figure 5). The current, with these assumptions, has a triangular course. This calculated value is only the current ripple in the magnetic element, the current circulating over the entire period in the magnetic element is equal to an average value which we call Io, which we set, for example, equal to 5A (current absorbed by the load) to which we superimpose the (triangular) ripple calculated equal to 2.5A (peak-to- peak). Therefore, a maximum current of 5+1.25 A = 6.25 A (at the end of t_on) inductance charged with energy and a minimum current of 5-1.25 A = 3.75 A (at the end of t_off), inductance discharged with energy, average current 5 A, will circulate in the magnetic element. Then the cycle repeats. It is evident that if the average current desired at the output, i.e., on the charge of the converter is less than 1.25 A, the converter goes into discontinuity because the current cancels out. In the case of a boost converter, the output power cannot drop below 125W, so the load must absorb no less than this power and the input energy source must provide at least this power + hardware efficiency losses. If the calculations are repeated for the same magnetic part and for a PWM application at 250 KHz that has a period of 4usec and therefore t_on of 2usec and t_off of 2usec. Then the ripple (peak-to-peak) current is 1 A and the discontinuity current is 0.5 A, so the minimum output power will be 50 W. This, by the principle of conservation of energy, is the power that the converter is able to draw in input if the converter is powered by a variable energy source in input, but it is an important piece of data if it is considered a renewable source. Powers below this value are unmanageable. Therefore, if frequency modulation is also introduced in the PWM modulation, (the passage from 100 KHz to 250 KHz is in all respects a frequency modulation), from which PWFM the operating range of the converter is extended, it is passed from a minimum power of 125 W to 50 W, in a linear relationship with the variation of the working frequency. If an interleaved boost converter with at least two phases (two 10 A inductors) were used with these parameters, the maximum power becomes 100 V x 20 A = 2 KW, while the minimum power is equal to 100 V x 0.25 A = 25 W per phase. This is thus a very wide operating range. The minimum power, if very low, can be easily managed and not wasted, and the DCM is avoided. For example, one can think of simple management by supplying a ballast load, or to provide auxiliary (service) energy to keep the converter itself active at all times, i.e., to make up for losses in efficiency, or below a certain current value (discontinuity limit) one simply switches the converter off.

The present invention will now be illustrated purely by way of example, but not by way of limitation or constraint, using the figures which illustrate some embodiments of the present inventive concept. Consider Figs. 2 and 3: these show a flow diagram of how an MPPT can be obtained with a DITHER routine from a power supply.

In the case shown, it is only necessary to detect the parameters of the power output from the converter. If the load is of a resistive or resistive-like type as a behaviour (e.g., in the case of batteries), is suffices to check the output voltage only. If the voltage increases the power increases by a factor V*V/R. There is no need for precision in the measurement since for the routine it is only necessary to know whether the output power increases or decreases as the duty-cycle varies. If the increase in output power, which is the objective to be achieved, occurred by increasing the duty-cycle, it continues in the direction of increasing the duty-cycle. It is not important to know the input conditions, and no other parameters are measured. In the same way, if the increase in power occurred due to a decrease in the duty cycle, it continues to decrease it. When the power decreases due to the increase of the duty-cycle, first the dutycycle is decreased (correcting the error) and the direction is changed, obtaining a subsequent value of the lower duty-cycle. At this point if the power has decreased as a result of decreasing the duty-cycle, it means that the direction of increase is wrong, as a result the duty-cycle is increased (error correction) and the direction is changed, thus obtaining the next higher dutycycle value.

The limit of the routine lies in the limitation of the range of increase/decrease of the duty-cycle of the PWM module on board the controller for which the range of intercepted and delivered power is limited. For this very reason the modification to modulate the frequency was introduced.

The increase in frequency results in an increase in the absorbed power (if the energy source is able to deliver it), the decrease in frequency results in a decrease in the energy absorbed by the source. The MPPT is an equilibrium that is achieved when the absorbed power is equal to that which can be supplied by the source. The MPPT, therefore, can only be achieved if the load can absorb all available energy at all times. For example, during energy exchange with the national AC electricity network it is easy to achieve equilibrium, even if the network is not exempt from the occurrence of cases of saturation (typically at night) for which the problem arises of finding a destination to which to direct energy. Other loads, such as batteries, or battery packs should be handled differently. It does not make sense, in fact, in these cases, to request the maximum power available at the input if it cannot be received by the load. The objectives to be achieved in the case in question are: to obtain a charge as complete as possible, and to achieve this in the shortest possible time.

Bearing in mind that a battery that is being charged progressively during charging limits the current absorbed (‘reject current’), the programme must also provide a load-directed MPPT, i.e., forcing the battery to absorb maximum power. In essence, it is necessary to obtain in this application an optimization of the charge in relation to both the available energy and the state of the battery.

With reference to the accompanying figures and particularly to Fig. 4 we observe the flow diagram that realizes what has been described above and is applicable to all types of charge and (in the case of the exemplary embodiment shown) the type of battery to be charged. The program provides for the setting of important parameters, that is, those relating to the maximum allowed values, for example the maximum voltage on the pack, maximum charging time at a certain voltage (for constant voltage charging phase), the maximum charging current and time (for constant current charging phase max), and the setting of the equalization phase parameters: maximum frequency and relative duty-cycle. These parameters vary depending on the type of battery and the load supplied to the battery. The converter according to the proposed invention manages several working points that can be calculated while the device is running or be pre-computed and inserted into a memory (by way of example and not limitation an EEPROM memory), or all these plus the data called up by the program when events occur.

The converter operates according to a timed loop. The converter normally works with the parameters set in the specific work point that we call Pn and, at the end of a set time, it measures the parameters and chooses between three possible situations.

• In the elementary case where only the pack voltage is to be checked, which is also an indication of the charge achieved, only this measurement is taken. If the voltage is lower (the battery is discharging) the program refers to the operation of the previous work point set for lower voltage.

• If the pack voltage is maintained in a range close to the current work point, the program loops on the same work point maintaining the same parameters (it is possible, however, to count the time and create a forced output).

• If the parameters have improved as a result of the higher voltage level achieved, work is carried out on the next point with the higher voltage to be achieved.

The output from the cycle is provided when the maximum voltage on the pack is achieved and if the absorbed current has achieved a set minimum. Either the time set for charging has elapsed, which must be predictable (input power always sufficient), or it is checked if there is a lack of input energy and the programme shuts down the controller and sends it into the LILPW (ultralow power wake-up) state. The controller switches off the modules and ceases operation until the event that “wakes” it occurs, such as the return of energy, and the program resumes its execution.

Finally, it is evident that modifications, additions or variants that are obvious to a person skilled in the art may be made to the invention described above, without departing from the scope of protection provided by the appended claims.

With reference to the enclosed drawings and in particular Fig. 7, an example of a converter corresponding to the proposed solution is shown on a physical and circuit level; this converter can be practically implemented according to any energy converter scheme buck, boost, transformer flyback etc. In particular, Fig. 7 shows how this converter is capable of changing the energy parameters, i.e., the voltage and current absorbed by the input minus the system’s efficiency losses. According to said diagram, the converter is driven by an electronic control unit that can be made by means of a microcontroller or microprocessor; said control unit receiving digital or analogue signals from the system and the external environment such as a temperature signal provided in analogue form or already digitized depending on the sensor used to detect it and/or for additional types of signal). The number and type of signals being those necessary for the control of the system, including those related to safety (maximum voltage, minimum, maximum power, current, maximum component temperature, batteries, etc.).

The PWFM modulation generated by the microcontroller or microprocessor drives the power switches of the converter which may for example be MOSFET, IGBT, Sic

The same control unit may also generate other types of signals to drive relays and other devices.

With reference to the accompanying drawings, and particularly to Fig. 8 the output signal from the control unit is represented according to the proposed system. Based on the control needs of the system, the control unit generates variable frequency and du ty_cycle signals over time.

In contrast to the standard PWM modulation in which a control unit generates a fixed frequency signal and only the duty_cycle is variable, i.e., only the pulse width varies; in contrast to the PFM and/or VFM (variable frequency modulation) frequency modulations in which the control unit generates pulses all of the same width but varying in number within the unit of time (therefore frequency).

Claims

Claims An adaptive energy converter with variable duty cycle and frequency modulation, said converter being capable of adaptively modifying its working point, i.e. the frequency and pulse width/duty cycle of a modulating signal adapted to drive a power element of the relay, transistor, MOSFET or functionally equivalent type; said power element being used to transform primary energy into secondary energy; said converter being characterized in that it comprises at least one microcontroller control unit (100) adapted, in turn, to contain a single microprocessor (101) adapted to produce a modulating signal comprising two amplitude and frequency modulations; said joint and simultaneous amplitude and frequency modulations being used to drive said power element; said microprocessor (101) comprising a memory with an algorithm for management of a pre-set working point dynamically adapted by said control unit (100), the operations of which are dependent on the type of desired behaviour, the outputs of which are directly executed by said energy converter (102). The energy converter with pulse modulation with variable pulse width and variable frequency according to the preceding claim 1, characterized in that the setting of the working point relating to frequency and duty cycle is provided by a mapping with inputs including at least one of: voltages, currents, frequencies, temperatures, both input and output, said mapping being stored on a memory (200) and loaded into the registers of said microprocessor (101) which must apply only the translation of said mapping without additional calculations. The energy converter with pulse modulation with variable pulse width and variable frequency, according to any one of the preceding claims, characterized in that it is applied to the charging and discharging of batteries or battery packs, by means of a load parameter meter (300) that allows a dynamic variation of the working point of said converter. The energy converter with pulse modulation with variable pulse width and variable frequency, according to any one of the preceding claims, characterized in that it comprises a plurality of sensors, such as, by way of example but not limited to, a thermometer (400), connected to said control unit (100); said control unit (100) using the data of said sensors to calculate a dynamic working point of the energy converter, consequently varying pulse or frequency. The energy converter with pulse modulation with variable pulse width and variable frequency, according to any one of the preceding claims, characterized in that said control unit (100) comprises an input energy meter (500) adapted to allow said microprocessor (101) to enter an inactive stand-by state, from which it exits, to return to operation according to the program, only on the return of input energy to said meter (500). The energy converter with pulse modulation with variable pulse width and variable frequency, according to any one of the preceding claims, characterized in that it comprises a clock external to said microprocessor (101) adapted to extend the range of frequencies that can be obtained with respect to the internal clock of the processor itself. A use of an energy converter with pulse modulation with variable pulse width and variable frequency, according to any of the preceding claims, in the context of the operation of equipment for the management of renewable energy sources, said converter being capable of varying the frequency, allowing it to intercept a very wide scale of energy quantities, while maintaining operation in continuous conduction mode and avoiding shutdown.