ITTO20121144A1 - ELECTRONIC LOCK OF A CLOSING DEVICE FOR A MOTOR VEHICLE, PROVIDED WITH A PERFECT RESERVE ENERGY SOURCE - Google Patents

Description

`` ELECTRONIC LOCK OF A LOCKING DEVICE OF A MOTOR VEHICLE, EQUIPPED WITH AN IMPROVED RESERVE ENERGY SOURCEâ €

The present invention relates to an electronic lock (commonly known as e-latch) of a locking device of a motor vehicle, provided with an improved backup power source.

In the following description and in the accompanying drawings, the expression "closing device" will be used to indicate in general any movable element between an open position and a closed position, respectively to open and close an access to an internal compartment of a vehicle. engine, thus including the trunk, doors, bonnet door or other closed compartments, window regulators, sunroofs, as well as the side doors of a motor vehicle, to which the following description will refer explicitly , by way of example only.

It is known that electric locks are provided in motor vehicles, for example to control the opening and closing of the side doors.

An electric door lock generally includes a fork selectively rotatable with respect to a striker fixed to a door pillar, for locking and unlocking the door. The electric door lock includes a latch which selectively engages the fork to prevent rotation of the fork. The electric door lock includes an electric motor, electrically connected to a main power source of the vehicle (for example to the 12 V battery of the same vehicle), to directly or indirectly operate the stop, through an electrically operated actuator.

As is known, a common problem associated with electric locks is to check, as required by safety regulations, the opening and closing of the doors even in the event of a malfunction of the vehicle's main electrical power source, o in the event of an interruption or break in the electrical connection between the main electrical power source and the electric motor in the lock; this type of situation can occur for example in the event of an accident or collision involving the vehicle.

One possible solution to this problem involves the use of a mechanical release mechanism in the lock, which serves as a manual alternative to the electrically activated side door lock.

However, the presence of a redundant mechanical mechanism results in a greater surface space and a higher weight, as well as additional costs, and also represents an additional constraint for the design of the door.

Therefore, the use of a backup power source in the electric lock has been proposed to provide electrical power to the electric motor of the lock in the event of a malfunction or interruption of the vehicle's main power source.

This backup power source is normally kept in a charged state during normal operation, by the primary power source, so that it is readily available as soon as it is needed, such as in the event of a collision or accident.

However, the integration of a backup power source and related electronic circuitry into the electric lock assembly proved to be a difficult task, due to the size requirements, and it proved difficult to even meet. the desired electrical performance, for example in terms of energy density or current output, in particular in the operating conditions of motor vehicles.

There is therefore a need in the industry for an optimized and reliable backup power source for an electric lock in a motor vehicle.

It is therefore an object of some aspects of the present invention to provide an electronic lock with a backup power source, designed to satisfy the aforementioned need.

This object can be achieved by means of an electronic lock as defined in the attached claims.

A preferred, non-limiting embodiment of some aspects of the present invention will be described by way of example with reference to the attached drawings, in which:

Figure 1 is a schematic representation of a motor vehicle with a locking device and an associated electronic lock assembly;

Figure 2 is a general block diagram of an electronic control circuit of the electronic lock assembly of Figure 1;

- figure 3 is a circuit diagram of the electronic control circuit of figure 2;

- figure 4 is a graph of an electrical signal in the electronic control circuit of figure 2; And

Figures 5a-5c show graphs of a capacitive quantity in the electronic control circuit of Figure 2, in different operating conditions.

The number 1 in figure 1 indicates as a whole an electronic lock group (â € œe-latch assemblyâ €), coupled to a side door 2 of a motor vehicle 3 (however it is emphasized again that the electronic lock group 1 can also be coupled to any type of locking device of the motor vehicle 3).

The electronic lock assembly 1 is electrically connected to a main power source 4 of the motor vehicle 3, for example a main battery which supplies a battery voltage Vbatt of 12 V, through an electrical connection element 5, for example a cable electrical (the main power source 4 may equally include a different source of electrical power within the motor vehicle 3, for example an alternator).

The electronic lock assembly 1 includes an actuation assembly 6 ', which includes an electric motor, which can be actuated to control the actuation of the door 2 (or in general of the vehicle locking device).

In a possible embodiment, the actuation assembly 6 'includes a fork 6, which is selectively rotatable to engage a striker 7 (fixed to the body of the motor vehicle 3, for example to the so-called "A-pillar" or "B-pillar "in a way not shown in detail). When the fork 6 is rotated into a locking position with respect to the striker 7, the side door 2 is in a closed operating state. A stop 8 selectively engages the fork 7 to prevent its rotation, driven by an electric motor 9 in such a way as to move between an engaged position and a non-engaged position.

The electronic lock assembly 1 also includes an electronic control circuit 10, which includes for example a microcontroller or other known computing unit, which can be suitably integrated and arranged in the same housing or casing 11 (shown schematically) with the actuation group 6 'of the electronic lock group 1, thus creating a compact and easy-to-assemble unit.

The electronic control circuit 10, as will be illustrated in greater detail in the following part, is coupled to the electric motor 9 and supplies to it actuation signals Sd.

The electronic control circuit 10 is electrically coupled to a vehicle main management unit (also known as the main ECU or "vehicle body computer") 12, which is configured to control the general operation of the motor vehicle 3, through a data bus 14, so as to exchange signals, data, commands and / or information.

Furthermore, as also illustrated in Figure 2, the electronic control circuit 10 is coupled to numerous different sensors 15 (schematically illustrated) of the motor vehicle 3, for example: handle reading sensors 15a (which read the actuation external and / or internal handles 16), impact sensors 15b, block switching sensors 15c, and the like; suitably, the electronic control circuit 10 also receives feedback information relating to the actuation of the lock from position sensors 15d, for example Hall sensors, configured to detect the operating position for example of the fork 6 and / or of the stop 8.

The electronic control circuit 10 is also coupled to the main power source 4 of the motor vehicle 3, so as to receive the battery voltage Vbatt. The electronic control circuit 10 is therefore able to check if the value of the battery voltage Vbatt decreases below a predetermined threshold value, immediately determining if an emergency condition occurs (when an energy source of reserve).

As illustrated in the schematic block diagram of Figure 2, the electronic control circuit 10 includes a backup power source 20, integrated and incorporated, which is configured to supply electrical power to the actuation assembly 6 'and to the electric motor 9 of the lock, and to the same electronic control circuit 10 in the event of a malfunction or interruption of the main power supply from the main power source 4 of the motor vehicle 3.

In greater detail, the electronic control circuit 10 includes a control unit 21, for example provided with a microcontroller, microprocessor or similar computing module 21a, coupled to the reserve power source 20 and to the actuation unit 6 'of the unit electronic lock 1, to check its operation.

The control unit 21 has an integrated memory 21b, for example a non-volatile random access memory, coupled to the computing module 21a, which stores suitable programs and instructions for a computer (for example in the form of a firmware). It is known that the control unit 21 can alternatively comprise a logic circuit with discrete components to perform the functions of the computing module 21a and of the memory 21b.

According to one aspect of the present solution, the backup energy source 20 includes a group of low voltage supercapacitors (or supercapacitors, `` supercaps '') 22 (hereinafter referred to as a group of supercapacitors 22), also known as double-layer electrolytic capacitors , as an energy supply unit (or energy reservoir) to supply an energy reserve to the electronic lock assembly 1, even in the event of an electrical malfunction.

Supercapacitors advantageously provide high energy density, high output current availability and have no memory effects; furthermore, supercapacitors are small in size and easy to integrate, have wide temperature ranges, a long lifespan, and can withstand a very high number of charge cycles. Supercapacitors are non-toxic and pose no risk of explosion or fire, making them suitable for hazardous conditions, for example in automotive applications.

In a possible embodiment, as illustrated in Figure 3, the group of supercapacitors 22 can include two supercapacitor cells 23a, 23b, connected in series between a first node 22a and a second node 22b (for example connected to a potential ground reference) and defining an intermediate node 22c, each providing, in the charged state, a voltage level of for example 2.5 V-2.7 V to jointly supply on the first node 22a a supercapacitor voltage Vsc, for example in the order of 3 V-5 V, which can be used as a backup power supply, in emergency situations, when the power of the main power source 4 of the motor vehicle is not available 3.

As will be discussed in greater detail below, the backup power source 20 further includes a charge module 24; an equalization module 25 and a boost module (â € œboostâ €) 26.

The charging module 24 is electrically coupled to the supercapacitor group 22 and is configured to continuously recharge, starting from the battery voltage Vbatt, when power is available from the main power source 4, the supercapacitor group 22 , in such a way that the same group of supercapacitors 22 can offer a complete energy reservoir for emergency situations and in such a way that any current leakage is compensated.

The equalization module 25 is electrically coupled to the supercapacitor assembly 22, and is configured to ensure that both supercapacitor cells 23a, 23b have a desired cell voltage value, in particular the same cell voltage value during the operation (to obtain a balanced operating condition). The equalization module 25 also prevents the supercapacitor cells 23a, 23b from having a cell voltage higher than a desired maximum cell voltage level, protecting the supercapacitors from overload.

The boosting module 26 receives at its input the supercapacitor voltage Vsc generated by the supercapacitor group 22, and is configured to boost, i.e. to increase, its value up to the standard voltages for motor vehicles (for example 9 V-16 V) and to provide sufficient output current capacity to drive standard automotive electric motors, for example electric motor 9 of electronic lock assembly 1. Indeed, the supercapacitor voltage Vsc may be too low to provide an effective backup power source to directly operate the electric motor 9 in emergency situations, for example in the case of an insufficient or no electrical supply from the main power source 4 of the motor vehicle 3.

The boost module 26 thus supplies at its output (which is also the output of the reserve energy source 20) a boosted voltage Vboost, as a function of the supercapacitor voltage Vsc. The boosted voltage Vboost is then received by an output module of the electronic control circuit 10, for example including an integrated bridge module H 27, whose output drives the electric motor 9 of the assembly 1 of the electronic lock group 1.

The backup power source 20 further includes a diagnostic module 28, which is operatively coupled to the supercapacitor assembly 22 and is configured to monitor the health of the supercapacitors during the charging process, by measuring their voltage value, the their capacitance value, and the internal equivalent resistance (DCR - Direct Current Resistance), again as will be discussed below.

A temperature sensor 29 is configured to monitor the operating temperature of the supercapacitor assembly 22, and is coupled to the diagnostic module 28 to provide the sensed temperature information.

The diagnostic module 28 is operatively coupled to the control unit 21, to provide it with diagnostic information, for example including the value of the supercapacitor voltage Vsc.

In greater detail, as shown in the schematic circuit diagram of Figure 3, the charge module 24 of the reserve energy source 20 has a first input 24a, which is adapted to receive a driving voltage Vdr, the value of which corresponds to the greater of the boosted voltage Vbooste the battery voltage Vbatt; in particular, the driving voltage Vdrà is equal to the battery voltage Vbatt during normal operation of the electronic lock group 1, to charge the supercapacitor group 22, and is equal to the boosted voltage Vboost from the boosting module 26 in emergency cases or malfunction.

The charge module 24 also has a second input 24b, which is adapted to receive a charge enabling signal En_ch from the control unit 21 of the electronic control circuit 10, i.e. a digital signal whose value is indicative of the need , determined by the control unit 21 itself, to enable or interrupt the charge of the supercapacitor group 22.

The charging module 24 includes a power switch 24c and a power resistor 24d.

The power switch 24c, for example a solid state switch such as a MOSFET switch, is connected between the first input 24a and the power resistor 24d, and has a control terminal coupled to the second input 24b, thus receiving the charge enable signal En_ch.

The power resistor 24d is coupled between the power switch 24c and the first node 22a of the supercapacitor group 22.

When enabled by the charge enabling signal En_ch through the power switch 24c, the charge of the supercapacitor group 22 to the battery voltage Vbattav comes through the power resistor 24d.

In particular, the control unit 21 of the electronic control circuit 10 can generate a PWM charge enable signal En_ch (with pulse width modulation), during the charge of the supercapacitor group 22, thus connecting and disconnecting rapidly the group of supercapacitors 22 in succession at the battery voltage Vbatt.

As previously indicated, the charging of the supercapacitor group 22 can be a continuous process, as long as the control unit 21 of the electronic control circuit 10 detects a value of the battery voltage Vbatts higher than a preset threshold, indicative of a possible malfunction. main power source 4.

The equalization module 25, in a possible passive embodiment, includes a first and a second equalization resistor 25a, 25b having the same resistance value. The first equalization resistor 25a is connected between the intermediate node 22c and the first node 22a of the supercapacitor group 22, through the interposition of a first equalization switch 25c, thus being selectively connectable in parallel to the first supercapacitor cell 23a; the second equalization resistor 25b is connected between the intermediate node 22c and the second node 22b of the supercapacitor group 22, through the interposition of a second equalization switch 25d, thus being selectively connectable in parallel to the second supercapacitor cell 23b.

The first and second equalization switches 25c, 25d are solid state switches, for example including a respective MOSFET transistor, both controlled by an equalization enable signal EN_eq received by the control unit 21 of the electronic control circuit 10 at of a control input 25e of the equalization module 25.

In particular, the equalization enable signal EN_eq controls the first and second equalization switches 25c, 25d to enable or disable the equalization process, to save the energy stored in the group of supercapacitors 22, when the same group of supercapacitors 22 It is not used as a backup power source.

The boost module 26 is implemented, in one possible embodiment, by a PWM boost converter (or dc-dc voltage boost converter) and includes an enable switch 26a, such as a MOSFET solid-state switch, connected between the first node 22a of the group of supercapacitors 22, thus receiving the supercapacitor voltage Vsc, and a first intermediate node 26b.

A storage capacitor 26b 'is coupled to the first intermediate node 26b, and is charged to the supercapacitor voltage Vsc when the enabling switch 26a is closed, defining on the same intermediate node 26b a self-activation signal S_ON having a high voltage value.

The enabling switch 26a has a control terminal which receives a boost OFF disable signal from the control unit 21 of the electronic control circuit 10; during normal operation, when the main power source 4 is available, the boost_OFF boost deactivation signal disables the PWM boost converter and keeps it in the OFF state, since the battery voltage Vbattracted is not critical .

The control terminal of the enabling switch 26a also receives a boost_ON enabling signal, the value of which is determined by external events (i.e. it is not generated by the control unit 21, inside the electronic control circuit 10 ), and the activation signal S_ON.

The boost module 26, after being activated, automatically maintains itself in an ON state, in particular due to the high value of the activation signal S_ON, until it is switched off by the control unit 21 of the control circuit. electronic 10, when the reserve energy is no longer needed or when energy needs to be accumulated in the supercapacitor group 22.

According to a possible embodiment, the boost_ON boost enabling signal is switched to the ON state, thus enabling the PWM boost converter, as soon as the handle reading sensors 15a detect the activation by the user of the internal handles. or external 16 of a side door 2 of the motor vehicle 3; therefore, in the event of an emergency, when a malfunction occurs in the main power source 4, the reserve power source 20 is immediately available to power the electronic lock unit 1.

In particular, the boost module 26 includes: a boost inductor element 26c connected between the first intermediate node 26b and a second intermediate node 26d; a boost switch 26e, for example a solid state switch such as a MOSFET switch, connected between the second intermediate node 26d and the ground reference potential and having a control terminal; and a boosting diode element 26f, connected between the second intermediate node 26d and an output node 26g (also representing an output terminal OUT for the reserve energy source 20 as a whole), on which the boosted voltage Vboost.

According to an aspect of the present solution, the boost module 26 further includes an internal controller 26h, in particular a PWM controller, which is configured to supply a PWM control signal to the control terminal of the boost switch 26e, in such a way to check its boost operation (in a known mode not discussed in detail here).

The internal controller 26h is coupled to the first intermediate node 26b, to receive the supercapacitor voltage Vsc, and is able to independently manage the activation and deactivation of the boosting, allowing to enable the reserve energy source 20 even without no other action by the control unit 21 of the electronic control circuit 10.

A feedback switch 26i is connected between the output node 26g and the internal controller 26h to provide feedback on the value of the boosted voltage Vboost.

The control terminal of the feedback switch 26i is also coupled to the first intermediate node 26b, to receive the activation signal S_ON, when the enabling switch 26a is closed.

When switched to the closed state by the supercapacitor voltage Vsc, a feedback path is defined which allows closed-loop voltage regulation by the internal controller 26h (a voltage divider, not shown, implemented through partition resistors, can be present to provide the voltage feedback starting from the boosted voltage Vboost).

The feedback switch 26i returns to the open state, as soon as the boost module 26 is deactivated, to reduce the power consumption on the feedback path, which is effectively interrupted.

The boosting module 26 further includes a selection diode 26j, having its cathode terminal connected to the output node 26g and its own anode terminal receiving the battery voltage Vbatt.

Consequently, on the output terminal OUT of the reserve energy source 20, the higher of the battery voltage V beats the boosted voltage Vboost, as the driving voltage Vdr, which will then drive the electric motor 9 of the electronic lock unit 1 ( and will also charge the supercapacitor group 22).

The operation of the diagnostic module 28 of the backup power source 20 is now discussed in greater detail.

In a possible embodiment, the diagnostic module 28 can be implemented in the control unit 21 of the electronic control circuit 10, as a diagnostic routine performed by the microprocessor or microcontroller of the computing module 21a; the control unit 21 can monitor for this reason the value of the supercapacitor voltage Vsce / or the voltage value in the intermediate node 22c between the supercapacitor cells 23a, 23b.

In a possible embodiment, the temperature sensor 29 can also be integrated inside the control unit 21.

Possible malfunction modes, which are monitored by the diagnostic module 28 and can affect any or both of the supercapacitor cells 23a, 23b, are:

- open circuit malfunction;

- short circuit malfunction;

- increased leakage current;

- increase of the equivalent series resistance;

- reduction of the value of capacity.

These malfunctioning modes can be detected in real time during the operation of the electronic lock unit 1, using a particular logic and particular algorithms provided by the diagnostic routine.

In particular, an "open circuit" malfunction for any of the two supercapacitor cells 23a, 23b generates a corresponding malfunction in the entire series, which can be detected whenever there is substantially zero voltage on the supercapacitor series, even if charged. .

A "short-circuit" malfunction of a supercapacitor cell 23a, 23b of the series generates a doubling of the series capacitance, and a corresponding reduction in the value of the supercapacitor voltage Vsc; the fully charged voltage value may not be reached and / or may not be maintained over time.

An increase in the "leakage current" can be detected when the charged state of the supercapacitor cells 23a, 23b (whose value can be set as a predefined threshold) is not obtained, even after a long charging time, or when the the value of the supercapacitor voltage Vsc on the series undergoes an unexpected variation (for example a variation not compatible with the charging process that is applied to the group of supercapacitors 22).

The increase in the "equivalent series resistance" of any of the supercapacitor cells 23a, 23b determines an increase in the resistance of the entire series, while the reduction of the "capacity" of any of the supercapacitor cells 23a, 23b determines an increase in the capacity of the entire series.

The open circuit and short circuit malfunctions cause a complete malfunction of the reserve energy source 20, since the energy storage function of the supercapacitor cells 23a, 23b is invalidated; in other words, the electronic lock unit 1 can operate appropriately only when powered by the main power source 4 of the motor vehicle 3.

On the contrary, the other malfunctions listed above are progressive; in particular, when the measured values (for example the capacitance or the resistance values) reach a first alarm threshold, which can be suitably predetermined, the diagnostic module 28 is able to generate a pre-alarm indicating the imminent malfunction at the user / driver or to the staff on duty, even when the supercapacitor cells 23a, 23b are still in a working state.

When the malfunction then reaches a limit value (and the measured values reach a second predetermined alarm threshold), the diagnostic module 28 can signal the complete malfunction of the backup energy source 20 and that the electronic lock unit 1 can only operate if connected to the main power source 4 of the motor vehicle 3.

According to an aspect of the present solution, the capacity of the supercapacitor cells 23a, 23b is estimated during their life cycle by the diagnostic module 28, measuring the time necessary for the supercapacitors to charge from a partially charged voltage to a fully charged voltage, when charging is implemented through a series resistor (the power resistor 24d of the charging module 24) directly from the power supply voltage (the battery voltage Vbatt of the main power source 4).

In particular, starting from a completely discharged state, the time T1 required to reach a partially charged voltage V1Ã ̈:

∠’T 1

V 1 = Vbatt (1 ∠’eR <â‹…> C)

while the time T2 needed to reach a fully charged voltage V2Ã ̈:

∠’T 2

V 2 = Vbatt (1 ∠’eR <â‹…> C)

where C is the capacitance of the supercapacitors (of the entire series, if we consider the supercapacitor voltage Vsc, or of a first of the supercapacitor cells 23a, 23b, if we consider the voltage on the intermediate node 22c), and R Ã ̈ the resistance of the power resistor 24d.

It follows that:

T1 = âˆ'Râ ‹… Câ‹… ln (1 ∠’<V 1>)

Vbatt

And:

T2 = âˆ'Râ ‹... Câ‹ ... ln (1 ∠’<V 2>)

Vbatt

The charging time ∠† T required for charging from partially charged voltage V1 to fully charged voltage V à ̈: ï £ «<V1> V ï £ ¶

∠† T2

= T2−T1 = Râ ‹... Câ‹ ... ï £ ¬ï £ ¬ln (1∠’) −ln (1 − <2>) ï £ ·

ï £ VbattVbatt ï £ ·

ï £ ̧

∠† T = Râ ‹… C â‹… ln (<V> batt ∠’<V> 2)

V batt ∠’V 1

or:

∠† T = Câ ‹... (Râ‹ ... (ln (Vbatt−V2) −ln (Vbatt∠’V1)))

and the value of the capacity C can be expressed as:

C = ∠† T / (Râ ‹... (ln (Vbatt−V2) −ln (Vbatt− V1)))

or:

∠† T

C =

K (Vbatt)

in which:

K (Vbatt) = (R⠋... (ln (Vbatt−V2) −ln (Vbatt− V1))

In particular, since R, V1 and V2 have predetermined and known values, it is possible to avoid complex logarithmic calculations during the runtime, if the values of K at the possible different battery voltages are pre-calculated and stored in a table (which can be included in the integrated memory 21b of the control unit 21).

As far as the accuracy of the capacity estimation by the diagnostic module 28 is concerned, it is possible to make the following considerations, referring to an example case and to exemplary values.

Resistance R can have an absolute accuracy of 5%; in this case the resistance of the power switch 24c, for example equal to 100 mâ „¦ (which should be added to the resistance R) is significantly lower than the value of 5%.

The time ∠† T can have an absolute accuracy of 2%, due to the tolerance of the internal oscillator over the entire temperature range (the oscillator being controlled and verified by the control unit 21, in a known mode, here not discussed in detail). If the charge of the supercapacitor group 22 is controlled in PWM through the power switch 24c, the charging time ∠† T is correct by multiplying it by the duty cycle of the PWM.

The voltage values appear as ratios and are not absolute values, so the absolute accuracy of the voltage measurements does not affect the accuracy of the capacitance estimate.

The battery voltage Vbatt must be reduced by the voltage drop on the selection diode 26j; this voltage is low, in terms of absolute value, and varies in a range of +/- 100 mV for a given current. An absolute accuracy of 3% can be associated with the measurement of the battery voltage Vbatt, also taking into account the discretization errors (due to the analog / digital conversion in the control unit 21 of the electronic control circuit 10).

The final precision in the measurement of the capacitance value is therefore about 10%, adding 5% for the resistance measurement, 2% for the time measurement and 3% for the voltage measurement and the error of discretization.

The value of the battery voltage Vbatt, although considered constant, during normal operation is subject to variations during the charging of the supercapacitor group 22.

To consider this aspect as well, the diagnostic module 28 is configured to measure the variation of the battery voltage Vbatte to stop or cancel the measurement of the capacitance C, if a variance of the battery voltage Vbatt during a given period of time is greater than a threshold value determined.

For low variance values of the battery voltage Vbatt, it is still possible to perform a calculation using the lower of the Vbatt values (among those detected in the period of time considered) in order to obtain a lower capacity estimate.

According to another aspect of the present solution, the equivalent series resistance (ESR) of the supercapacitor group 22 is estimated, during operation, by the diagnostic module 28, in particular to check if it is lower than a maximum required value.

When a charge current is applied the voltage in the supercapacitor group 22 is increased by the product of the charge current times the equivalent series resistance. In particular, when the charging current is zeroed, the value of the supercapacitor voltage Vsc immediately decreases with a voltage drop across the equivalent series resistor.

Using an analog / digital converter with a resolution of n bits, for example 10 bits and a full scale voltage (FS) of for example 5 V, the resolution dV for the measurement of the supercapacitor voltage Vscà ̈:

<FS> 5

dV = n = V 5 mV

2 2 <10> =

The aforementioned AD converter can be implemented inside the control unit 21, in particular by the computing module 21a.

The nominal value of ESR can be equal to or less than 100 mâ „¦ therefore, to obtain a resistance resolution dR of for example 10 mâ„ ¦ (one tenth of the average value), the minimum charge current Ichà ̈:

<dV> 5

<I> ch = = = <500> mA

dR10

The resistance R of the power resistor 24d is calculated as follows:

V.

= batt <∠’> V sc 12V <−> 5 V

R = = 14 â „¦

I ch 500 mA

considering a minimum value for ESR detection for the battery voltage V, it beats a maximum value for the supercapacitor voltage Vsc.

As discussed above, the power switch 24c in the charge module 24 can be suitably controlled through a PWM modulation scheme, to reduce the power dissipation on the power resistor 24d.

In this regard, figure 4 shows a possible PWM trend of the supercapacitor voltage Vsc, during the charging of the supercapacitor group 22 having, for each period, an ON phase followed by an OFF phase, whose respective duration is determined by the duty cycle of the charge enable signal En_ch.

In this situation, advantageously, the resistance measurement can be performed in each period of the charge enabling signal En_ch in the OFF phase of the duty cycle (i.e. when the charging current is canceled due to the opening of the power switch 24c ). A suitable average of the different measures can be implemented to obtain a resulting average value.

On the basis of the above, the ESR can be estimated with the following expression:

∠† V

ESR = R sc

Vbatt ∠’V sc

where ∠† Vscà ̈ the voltage drop across the supercapacitor group 22 due to the charging current Ich.

Voltages are used as ratios, so the corresponding accuracy of the AD converter is not relevant to the overall accuracy of the measurement.

The measurement tolerance on R is about 5% and is reflected instead on the ESR measurement.

If the voltage accuracy is 0.5%, the total estimation error is expected to be less than 10%.

According to a further aspect of the present solution, the diagnostic module 28 is also configured to consider the temperature conditions in which the electronic lock group 1 and the supercapacitor group 22 operate. These temperature conditions are monitored by the temperature sensor 29.

In fact, the performance of a supercapacitor is directly affected by temperature conditions and operating life.

As illustrated in figures 5a-5c, the capacity of a supercapacitor is directly related to its life span, showing a decrease over time (the relationship between a final value Cf and an initial value Ci is shown); furthermore, the rate of this decrease is influenced by the operating temperature and by the initial voltage value of Vinello itself as supercapacitor.

Automotive systems must be able to withstand very high temperatures (for example up to 70 ° C-100 ° C), while ensuring correct operation, or at least avoiding malfunctions.

In the present solution, the group of supercapacitors 22 must ensure a reserve of energy to allow the user to exit the vehicle in the event of a malfunction (for example, malfunction of the battery, fuses or electrical wiring); at high temperatures, for example 70 ° C-100 ° C, the user cannot be trapped inside the motor vehicle 3.

To allow an appropriate use of the supercapacitor group 22 even at high temperatures, the diagnostic module 26 is therefore configured to implement a suitable strategy for reducing the value of the supercapacitor voltage Vsc, as the temperature increases (this value being controlled by an appropriate modification of the charging process through the charging module 24).

In particular, the strategy implemented by the diagnostic module 28 provides for three different operating conditions, in respective temperature ranges;

- for temperatures between -Temp1 and Temp1, in which Temp1 is a first temperature threshold, whose absolute value is about 38 ° C-42 ° C, for example 40 ° C, the group of supercapacitors 22 is fully maintained load (e.g. with a voltage level of each supercapacitor cell 23a, 23b in the range 2.5V-2.7V);

- for temperatures between Temp1 and Temp2, in which Temp2 is a second temperature threshold, whose absolute value is approximately 85 ° C-90 ° C, for example 85 ° C, a voltage decrease, for example of a linear type between a first value (for example 2.5 V) and a second value lower than the first (for example 2.1 V) it is applied to the supercapacitor voltage Vsc; And

- for temperatures higher than Temp2, the group of supercapacitors 22 is discharged up to a supercapacitor voltage Vscaving a third value, lower than the second value (for example 1 V for each supercapacitor cell 23a, 23b).

According to the aforementioned temperature strategy, the decrease of the supercapacitor voltage Vsca at higher temperatures allows to reduce the effect of the capacity variations over time, thus improving the reliability of the supercapacitor group 22, for example when used in the energy source of reserve 20. Furthermore, the life span of the same group of supercapacitors 22 is extended.

In general, supercapacitors are available when actually needed and it is possible to obtain an improved life; in this regard it has been demonstrated, with a simulation, that this control strategy allows to obtain a reliable duration of at least 15 years for the group of supercapacitors 22.

The advantages of the solution discussed clearly emerge from the above description.

In particular, a reliable backup power source 20 is provided for automotive applications, for example to power the electronic lock assembly 1 in the event of a malfunction of the main power source 4 of the motor vehicle 3, and / or in the case disconnection of the electronic lock group 1 from the same main power source 4.

The backup power source 20 can be independently controlled by the internal control unit 21, and can also be turned on and off without any action by the vehicle's main management unit 12 and associated control software.

The use of supercapacitors allows to realize the reserve energy source 20 in an inexpensive, light and small container; the resulting size and form factor of the reserve power source 20 are such as to allow its integration within the same enclosure 11 of the electronic lock assembly 1.

The use of supercapacitors also allows to obtain a high energy density, a high output current capacity, and avoids memory effects by minimizing consumption and recharging time.

Furthermore, the present solution allows to promptly diagnose any failure of the supercapacitor cells 23a, 23b in the supercapacitor group 22, for example open or short circuit conditions, increase in the leakage current, increase in the equivalent series resistance and / or decrease in the value of capacity .

The discussed temperature control strategy allows the supercapacitors to be used reliably as a backup energy source 20 even at very high temperatures, so as to satisfy the safety requirements, in particular associated with automotive applications.

Clearly it is possible to make changes to what is described and illustrated herein without however departing from the scope of protection defined in the attached claims.

In particular, the electrical connection of the supercapacitor cells 23a, 23b could be a parallel connection, rather than a series connection, to provide the supercapacitor voltage Vsc, required as a backup supply voltage for the actuation assembly 6 'of the motor vehicle 3. The number of supercapacitor cells can also be different.

Furthermore, it is again emphasized that the electronic lock assembly 1 can operate any type of different locking device inside the motor vehicle 3.

In general, the backup power source 20, and the control and diagnostic algorithms discussed for checking the state of the supercapacitor cells 23a, 23b can also be used for other purposes, inside the motor vehicle 3, for different applications. automotive.

Claims (19)

Prot. N. TO2012A001144 CLAIMS 1. Electronic lock assembly (1) for a locking device (2) of a motor vehicle (3) comprising an actuator (6, 8) operable to actuate the locking device (2) and an electric motor (9) controllable to operate the actuator (6, 8), the electric motor (9) being able to be powered, during a normal operating condition, by a main power source (4) of the motor vehicle (3) providing a voltage of main power supply (Vbatt); wherein the electronic lock assembly (1) includes a back-up power source (20), and a control unit (21) configured to control the back-up power source (20) to power the electric motor (9) during a malfunction operating condition, other than the normal operating condition, characterized in that the backup power source (20) includes a group of supercapacitors (22) configured to accumulate energy during the normal operating condition and to provide a supply voltage reserve (Vsc) to power the electric motor (9) during the malfunction operating condition. Assembly according to claim 1, wherein the supercapacitor assembly (22) includes at least a first supercapacitor cell (23a) and a second supercapacitor cell (23b), connected to each other, to jointly supply the backup supply voltage (Vsc ). Assembly according to claim 1 or 2, wherein the backup power source (20) includes a charging module (24), controllable by the control unit (21) for continuously charging the supercapacitor assembly (22 ) during normal operating conditions, when the main power supply voltage (Vbatt) is greater than a preset threshold; wherein the charge module (24) includes a charge resistor element (24d) coupled to the supercapacitor assembly (22), and a charge switch element (24a) coupled between an input terminal (24a) which receives the main power supply (Vbatt) and the charge resistor element (24d), and having a control terminal; wherein the control unit (21) is configured to provide a charge control signal (En_ch) to the charge switch element control terminal (24a) to control the charge of the supercapacitor assembly (22). Group according to claim 3, wherein the charge control signal (En_ch) is a pulse width modulated signal, during the normal operating condition, having a duty cycle defining an ON phase, when the group of supercapacitor (22) is charged by the main supply voltage (Vbatt), and a phase switched OFF, when the charge of the supercapacitor group (22) is interrupted. Assembly according to any one of the preceding claims, wherein the supercapacitor assembly (22) includes at least a first supercapacitor cell (23a) and a second supercapacitor cell (23b), connected in series to provide the backup supply voltage (Vsc ); wherein the backup power source (20) includes an equalization module (25), coupled to the supercapacitor assembly (22), and operable to define a desired voltage level on each of the first (23a) and second ( 23b) supercapacitor cell; wherein the equalization module (25) includes a first equalization resistor element (25a), adapted to be selectively connected in parallel to the first supercapacitor cell (23a) by a first equalization switch element (25c) controlled by a signal of equalization (En_eq) provided by the control unit (21), and a second equalization resistor element (25b) adapted to be selectively connected in parallel to the second supercapacitor cell (23b) by a second controlled equalization switch element (25d) from the equalization signal (En_eq); where the equalization signal (En_eq) is designed to selectively interrupt the current flow in the first (25a) and second (25b) equalization resistor element when the supercapacitor assembly (22) does not provide the backup supply voltage (Vsc) to the electric motor (9). Group according to any one of the preceding claims, in which the reserve energy source (20) further includes a voltage booster module (26), coupled to the supercapacitor group (22) and operable to boost a level of the supply voltage reserve voltage (Vsc) to supply a boosted voltage (Vboost), higher than the reserve power supply voltage (Vsc) suitable for powering the electric motor (9). The assembly according to claim 6, wherein the voltage booster module (26) includes a boost voltage converter, having an internal controller (26h) and a boost activation switch element (26a), selectively enabled to activate the controller internal (26h) to implement the boosting operation, from an external signal (boost_ON) indicative of an external operation on the closing device (2); in which the internal controller (26h) is configured to maintain the boost operation, until it is deactivated by the control unit (21) through a deactivation signal (boost_OFF). Group according to any one of the preceding claims, wherein the backup power source (20) includes a diagnostic module (28) coupled to the supercapacitor group (22) and configured to monitor a relative operating state, detecting at least one value of the reserve power supply voltage (Vsc); in which the diagnostic module (28) is configured to detect one or more of the following malfunction modes of the supercapacitor assembly (22): an open circuit malfunction; a short circuit malfunction; an increase in a leakage current; an increase in an equivalent series resistance (ESR); a reduction in the value of capacity (C). The assembly according to claim 8, wherein the diagnostic module (28) is executed by the control unit (21) during the operation of the electronic lock assembly (1), and is configured to estimate the capacity value of the supercapacitor group (22) by monitoring the time (∠† T) required to charge the supercapacitor group (22) from a predetermined partially discharged voltage (V1) to a predetermined fully charged voltage (V2) for the backup supply voltage ( Vsc). Assembly according to claim 9, wherein the backup power source (20) includes a charging module (24), controllable by the control unit (21) for charging the supercapacitor assembly (22) from the supply voltage main (Vbatt) through a charge resistor element (24) having a resistance (R); where the diagnostic module (28) is configured to estimate the capacitance value of the supercapacitor group (22) through the following expression: ∠† T C = K (Vbatt) where K is given by: K (Vbatt) = (Râ ‹... (ln (Vbatt−V2) −ln (Vbatt− V1) and it is pre-calculated for different values of the main supply voltage (Vbatt) and stored in a table in a memory of the control unit (21). The assembly according to any one of claims 8 to 10, wherein the diagnostic module (28) is executed by the control unit (21) during the operation of the electronic lock assembly (1), and is configured to estimate the equivalent series resistance (ESR) of the supercapacitor group (22) to check if it is less than a predetermined maximum value; wherein the backup power source (20) includes a charging module (24), controllable by the control unit (21) for charging the supercapacitor assembly (22) with a charging current (Ich), and the module diagnostic (28) is configured to estimate the equivalent series resistance (ESR) by measuring a voltage drop across the supercapacitor assembly (22), when the charge is interrupted and the charge current (Ich) zeroed. The assembly according to claim 11, wherein the charging module (24) is controllable to charge the supercapacitor assembly (22) from the main supply voltage (Vbatt) through a charging resistor element (24d) having a resistance ( R); where the diagnostic module (28) is configured to estimate the equivalent series resistance (ESR) of the supercapacitor group (22) through the following expression: ∠† V ESR = R sc Vbatt ∠’V sc where ∠† Vscà ̈ the voltage drop across the supercapacitor group (22). Assembly according to claim 11 or 12, wherein the charge module (24) includes a charge resistor element (24d) coupled to the supercapacitor assembly (22), and a charge switch element (24a), coupled between a input terminal (24a) receiving the main supply voltage (Vbatt) and the charging resistor element (24d), and having a control terminal; wherein the control unit (21) is configured to provide a charge control signal (En_ch) to the control terminal of the charge switch element (24a) to control the charge of the supercapacitor assembly (22), the charge control signal (En_ch) being a pulse width modulated signal, during normal operating condition, having a duty cycle defining an ON phase, when the supercapacitor group (22) is loaded by the main supply voltage (Vbatt) and an OFF phase OFF when the charge of the supercapacitor group (22) is interrupted; where the diagnostic module (28) is configured to estimate the equivalent series resistance (ESR) of the supercapacitor group (22) during the OFF phase of the duty cycle of the charge control signal (En_ch), when the charging current ( Ich) is canceled by the opening of the charge switch element (24a). Assembly according to any one of the preceding claims, wherein the backup power source (20) includes: a charging module (24), controllable by the control unit (21) for charging the supercapacitor assembly (22); and a diagnostic module (28), coupled to the supercapacitor group (22) and configured to monitor the operating temperature of the supercapacitor group (22) and to cooperate with the charging module (24) to implement a charging strategy, in operation of the detected operating temperature. Group according to claim 14, wherein the charging strategy comprises three different charging conditions in respective temperature ranges, according to which: - for temperatures between -Temp1 and Temp1, the group of supercapacitors (22) is kept fully charged, with Temp1 being a first predetermined temperature value; - for temperatures between Temp1 and Temp2, a voltage reduction between a first voltage value and a second voltage value, lower than the first voltage value, is applied to the reserve supply voltage (Vsc), with Temp2 being a second predetermined temperature value, greater than the first predetermined temperature value; And - for temperatures higher than Temp2, the group of supercapacitors (22) is discharged to a third voltage value, less than the second voltage value. 16. Group according to claim 15, wherein the first set temperature value (Temp1) is in the range 38 ° C-42 ° C, and the second set temperature value (Temp2) is in the range 85 ° C -95 ° C. Assembly according to any one of the preceding claims, wherein the backup power source (20) and the control unit (21) are integrated and incorporated within an enclosure (11) of the electronic lock assembly (1 ). An assembly according to any one of the preceding claims, wherein the malfunction operating condition includes one of: a malfunction of the main power source (4) of the motor vehicle (3) which supplies the main power supply voltage (Vbatt); a malfunction of an electrical connection (5) connecting the electronic lock assembly (1) to the main power source (4) of the motor vehicle (3). 19. Motor vehicle (3), comprising a locking device (2) and, coupled to the locking device (2), an electronic lock assembly (1) according to any one of the preceding claims.