FR3066055B1 - DEVICE FOR CONTROLLING A STEP-BY-STEP MOTOR FOR ACTIVATING A MOBILE AIRBORNE IN A VEHICLE. - Google Patents

Abstract

The invention relates to a device for controlling at least one mobile flap (2) driven by a stepper motor (31) controlled by a control circuit, in a heating, ventilation and / or air conditioning system for a vehicle. . According to the invention, the control circuit comprises: at least one diode (D) for protecting the stepper motor (31) against overvoltages, the so-called freewheeling diode, a reception input of a first signal representative of a temperature and / or a reception input of a second signal representative of a voltage of a power supply source, and - means for determining a control frequency of the engine control signal step-by-step (31) according to at least one of said first and second signals.

Description

The present invention relates to the field of aerodynamics and more particularly the field of shutter actuators or mixing air or recirculation in heating, ventilation and / or air conditioning of motor vehicles, often referred to as "HVAC" .

In such installations, the position of the opening and closing flaps of an air duct, called aeraulic flaps, is generally controlled by means of electromechanical actuators in response to actuation commands produced by a control module according to the needs to be satisfied, such as starting or stopping ventilation, adjusting the ambient temperature, demisting, defrosting, etc.

Electromechanical actuators generally comprise a geared motor adapted to actuate one or more ventilator flaps.

The electric motors of the geared motors, which are generally stepper motors, are chosen to deliver the power required to drive the flaps under all circumstances at a given speed, that is to say, whatever the fluctuations of the supply voltage and the torque requirements. The torque requirements are variable not only according to the technology of the flaps and the nature of their drive kinematics, but also according to instantaneous conditions such as the ventilation power, the back pressure exerted on the flap and 'opposed to the desired movement, the temperature ...

During a change of air conditioning adjustment, the movement of the geared actuator elements of the actuator, can generate vibrations and noise that are noticeable in the passenger compartment.

These vibrations and noise of movements of the actuators, perceived by the occupants in the passenger compartment of the vehicle, can cause discomfort for the latter and give a low-quality impression of the vehicle or equipment of this vehicle.

To reduce these unwanted noises, it has been proposed to use control signals from these stepper motors which do not have an acceleration ramp (consisting of a predetermined number of pulses of decreasing duration allowing obtain a larger motor starting torque), to reduce the speed of the angular displacement of the stepper motor (in particular by acting on the frequency of the motor control).

These solutions reduce the noise without removing the presence.

Thus, there is noise in the passenger compartment due to step motor power supply peaks which occur when the power of a phase of the stepper motor is interrupted and a another phase is powered. The invention therefore aims to further limit the vibrations and noise perceived by the occupants of the motor vehicle. To this end, the subject of the invention is a device for controlling at least one movable flap driven by a stepper motor driven by a control circuit, in a heating, ventilation and / or air conditioning system for a vehicle. .

According to the invention, the control circuit comprises: at least one protection diode of the step-by-step motor, said free-wheeling diode, a reception input of a first signal representative of a temperature, and or a reception input of a second signal representative of a voltage of a power supply source, and means for determining a control frequency of the control signal of the stepper motor as a function of at least one of said first and second signals. The invention proposes a device for controlling a step-by-step actuator motor which implements: on the one hand a protection circuit, comprising at least one freewheeling diode, in the control circuit of the stepping motor so as to trim the voltage spikes / overvoltages occurring when the power supply of a phase of the step-by-step motor is interrupted and another phase is energized. This clipping decreases the power of the stepper motor, and therefore the torque delivered by the latter and consequently the noise, which improves the acoustics of the passenger compartment of the vehicle, and - on the other hand, due to the reduction of the output torque of the stepper motor due to the implementation of the freewheeling diode, means for adapting the stepping motor frequency of the stepper motor under severe temperature conditions (increase in temperature) or when the battery voltage of the vehicle is low, so as to increase the torque and ensure the actuation / movement of the flap at a lower speed. The adaptation of the driving frequency can be achieved by continuously collecting information representing the temperature and / or information representing the voltage of the power supply source, such as a battery, and decreasing, if necessary, the frequency in response to a drop in battery voltage or a detected increase in temperature. The invention makes it possible to satisfy the torque requirements of the stepper motors, without increasing the parasitic noise and without appreciably penalizing the speed of execution of the operating commands of the air shutters controlled by these motors. The invention also makes it possible to reduce vibrations and parasitic noise in the passenger compartment, so as to improve the quality perceived by the driver of the heating, ventilation and / or air-conditioning system of the motor vehicle.

According to a possible characteristic, the driving frequency is lowered when the voltage of the power supply source is lower than a first given threshold value and / or when the temperature is greater than a given second threshold value.

According to one possible characteristic, the driving frequency can take at least two distinct frequencies, a nominal frequency and a reduced frequency, depending on the voltage of the power supply source and / or the temperature.

According to one possible characteristic, the means for determining a driving frequency takes account of at least one hysteresis cycle.

According to a possible characteristic, a hysteresis cycle for a control frequency change corresponds to a variation of the first signal representative of a temperature between a low threshold value and a high threshold value.

According to a possible characteristic, a hysteresis cycle for a control frequency change corresponds to a variation of the second signal representative of a voltage between a low threshold value and a high threshold value.

According to a particular embodiment, the control device controls at least two stepper motors each controlling the movement of a movable flap.

According to a particular embodiment, the control device comprises at least one freewheel diode per phase of the stepper motor.

According to one possible characteristic, said first signal representative of a temperature corresponds to an estimation of the temperature in the vicinity of the stepping motor. The invention will be better understood on reading the description given below by way of indication but without limitation with reference to the accompanying drawings, in which: FIG. 1A illustrates, in a schematic and partial manner, the components of an installation of heating, ventilation and / or automobile air conditioning of a motor vehicle in which the invention is implemented; FIG. 1B diagrammatically represents an exemplary control circuit configuration of a stepper motor according to the invention; FIG. 2 graphically illustrates the variation of the torque delivered by an actuator step-by-step motor as a function of the temperature and the supply voltage of the motor; - Figures 3 and 4 illustrate hysteresis cycles may be implemented according to the invention for a control respectively as a function of voltage and temperature.

Figure IA partially shows the components of a heating, ventilation and / or air conditioning of a motor vehicle in which the invention is implemented.

Such an installation conventionally comprises distribution or air mixing or recirculation shutters in order to achieve desired ventilation functions, cabin temperature control, demisting, defrosting, etc.

These functions are controlled by a user from commands located in the passenger compartment of the motor vehicle, on the dashboard for example. The installation conventionally comprises a plurality of actuators (only one of which is shown in FIG. 1A) to control the movement of the flaps.

A shutter 2 for controlling an air flow is controlled by means of an actuator 3, itself controlled by a control circuit comprising a control module 1. The actuator 3, which is connected to the flap 2, is preferably an electromechanical actuator comprising a three-phase electric stepper motor 31 and a gear train which acts as a geared motor element 32.

Typically, the control module 1 comprises data processing means, for example a microprocessor or a microcontroller 4, associated with a memory 5.

Conventionally, the control module 1 is directly associated with the controls located in the passenger compartment of the motor vehicle.

Thus, the actuation by a user of a command C generates a reference signal XC which corresponds to a setpoint position of the shutter. This XC setpoint signal transmitted by a CAN data bus is then received by the control module 1.

When the control module 1 receives this reference signal XC, the microprocessor 4 transmits a control signal to a control interface 6 of the control module 1 which generates a command and power supply signal SC to start the engine. This control and power supply signal SC consists of a pulse train applied to the phases of the stepper motor 31 at a given driving frequency (for example 200 Hz). under a supply voltage of the stepper motor 31 equal to 12V, for example.

The stepper motor 31 of the electromechanical actuator 3 is sized to have a sufficient starting torque to overcome the locking torques of the stepping motor 31 and the flap 2.

An installation as described above is known to those skilled in the art, so that a more detailed description is not necessary.

As noted above, during a power supply change of the phases of the stepper motor 31, power supply voltage peaks (of the order of 36V) of the motor are observed. These overvoltages are at the origin of parasitic noise in the passenger compartment that the invention proposes to attenuate.

To do this, a voltage clipping circuit, including one or more freewheeling diodes, is incorporated in the driving circuit 6 of the stepper motor 31 so as to clipping (i.e. ) these voltage spikes / overvoltages and improve the acoustics of the passenger compartment of the vehicle.

This voltage clipping is, for example, obtained by a parallel connection on the three-phase three-phase stepper motor 31, each of the diodes being associated with a phase of the motor.

This particular embodiment of the diodes is shown schematically in FIG. 1B, which illustrates an exemplary driving circuit of a three-phase stepper motor 31. The control circuit notably comprises the microprocessor 4, the control interface 6 and the control and power supply wires of the three phases of the stepper motor 31 on each of which a freewheeling diode D is mounted.

It may, for example, be PN junction diodes. Other means of voltage clipping can be implemented, such as in particular one or more transistors or operational amplifiers.

These clipping means can be integrated in the control module 1, in the actuator 3 or in the connections connecting the control module 1 to the actuator 3.

However, it has been found by the inventors that the implementation of such a protective diode reduces the torque delivered by the stepper motor 31 and therefore the effectiveness of the latter to control the movement of the shutter 2.

FIG. 2 shows the influence of the temperature T (in ° C) and the supply voltage (in V) of the vehicle battery on the torque (in N.cm) delivered by the step-by-step motor 31, at a given driving frequency of the motor (ie 200 Hz).

The curve Ci in solid line represents the couples obtained for different temperatures T and a constant voltage U1 of the battery, without a free-wheeling diode in the control circuit of the stepping motor 31.

Curve C2 in dotted lines represents the couples obtained for different temperatures T and a voltage U1 of the battery when, according to the invention, a freewheeling diode is incorporated in the control circuit 6 of the stepper motor 31 .

The torque Cmin corresponds to a minimum value below which the output torque of the stepping motor 31 does not allow the displacement of the flap 2.

In practice, a vehicle can be operated between temperatures between -40 ° C and + 85 ° C, while the voltage of the battery which is for example 12.5 V at standstill, can reach 16V, when the engine is running. It can also go down to around 10.5 V in some cases.

It can be seen that, if the power parameters of the stepping motor 31 are left constant, the output torque C of the latter can vary relatively significantly, as a function of the temperature as well as the voltage of the motor. drums.

It is furthermore noted that with the freewheeling diode (curve C2), under a given value Umin (equal to 11V, for example), the battery voltage and / or at high temperature (between 75 and 85 ° C. C, in the example shown), the torque C delivered by the stepping motor 31 may be too small to cause the displacement of the flap 2.

According to the invention, the control module 1 is programmed so as to possibly modify the driving frequency of the stepper motor 31, and therefore the speed thereof, depending on either information representative of the vehicle battery voltage received by the control module 1, either information representative of the vehicle temperature received by the control module 1, or both.

P1 sensors; P2 are used to respectively measure the temperature as well as the supply voltage of the vehicle battery. The first and second signals supplied by these sensors Ρυ P2 are received by the control module 1, through the CAN bus or not.

The first signal provided by the sensor Pi may correspond to the outside temperature, to the interior temperature of the vehicle or to an estimate of the temperature around the actuator 3, for example. The invention makes it possible, for these low voltages of the battery (lower than Umin) and / or at high temperatures (between 75 and 85 ° C, in the example shown), to increase the torque delivered by the motor not-to -No 31 by decreasing the driving frequency (200 to 125 Hz for example) of the stepper motor 31, without it being necessary to significantly complicate the heating, ventilation and / or air conditioning of the vehicle.

Indeed, for a given temperature and voltage, the torque of the stepping motor 31 increases when its driving frequency (advantageously between 50 and 500 Hz) decreases.

The driving circuit 6 of the stepper motor 31 thus adapts the driving frequency of the stepper motor 31, decreasing it, to "give back" torque for low battery voltages and / or temperatures. high, and thus operate the flap 2.

This corresponds to a control mode of the stepper motor 31 called "degraded".

The curve C'2 of FIG. 2 corresponds to the torque (in N.cm) delivered by the stepping motor 31 when the latter is driven in "degraded" mode. As illustrated by the arrow located between the curves C2 and C'2, the decrease in the driving frequency of the stepping motor 31 allows an increase in the torque delivered by the latter.

FIG. 3 illustrates an embodiment of the invention for which, when the voltage of the battery is greater than U2 (equal to 10.4V for example), the frequency F is equal to Fnom (equal to 200 Hz for example) .

On the other hand, when the voltage of the battery is lower than U1 (equal to 9.9V for example), the frequency F is equal to F | 0W (equal to 125 Hz for example).

In this way, it is possible to lower the frequency of Fnom F | 0W, and thus increase the torque of the stepper motor 31 when the battery voltage becomes low. The hysteresis cycle makes it possible, when the voltage decreases from the value U2, to maintain the value Fnom until the voltage reaches the value U1, and when the voltage increases from a value lower than U1, to maintain the value F | 0W until the voltage reaches the value U2.

Note that the voltage of the battery represented on the abscissa axis is slightly greater than the voltage across the terminals of the stepper motor 31.

FIG. 4 illustrates an embodiment of the invention for which, when the temperature is lower than T1 (for example T1 = 70 ° C.), the driving frequency F is equal to Fnom (for example F2 = 200 Hz). On the other hand, when the temperature is greater than T2 (for example T2 = 75 ° C.), the frequency F is equal to F | 0W with F | Ow <Fnom (for example F | OW = 125 Hz), which makes it possible to increase the output torque of the step motor 31 and move the flap 2.

The hysteresis cycle makes it possible, when the temperature increases from a value lower than T1, to maintain the driving frequency at the value Fnom until the temperature reaches T2, in which case it switches to the value F | 0W, and when the temperature decreases from a value greater than T2, to maintain the frequency F at the value F | 0W until T reaches Tl, in which case it switches to Fnom ·

The implementation of hysteresis cycles, rather than simple thresholds, makes it possible to avoid instabilities. The adaptation of the driving frequency of the stepping motor 31 so as to vary the output torque of the stepper motor 31 can take into account both the battery voltage and the temperature, or only one of these parameters.

It should be noted that the same engine can be used to drive several components.

It is also possible to associate one or more freewheeling diodes with each step of the step-by-step motor. Other sources of power than a battery can be used.

Claims (9)

Device for controlling at least one mobile flap (2) driven by a stepper motor (31) driven by a control circuit, in a heating, ventilation and / or air-conditioning system for a vehicle, characterized in that the control circuit comprises: at least one diode (D) for protecting the stepper motor (31) against overvoltages, the so-called freewheel diode, a reception input of a first signal representative of a temperature and / or a reception input of a second signal representative of a voltage of a power supply source, and means for determining a control frequency of the control signal of the stepper motor ( 31) according to at least one of said first and second signals. 2. Control device according to claim 1, characterized in that the driving frequency is lowered when the voltage of the power supply source is lower than a first threshold value and / or when the temperature is greater than a second value. threshold. 3. Control device according to claim 2, characterized in that the driving frequency can take at least two distinct frequencies, a nominal frequency and a reduced frequency, depending on the voltage of the power supply source and / or temperature. 4. Control device according to any one of claims 1 to 3, characterized in that the means for determining a control frequency takes account of at least one hysteresis cycle. 5. Control device according to claim 4, characterized in that a hysteresis cycle for a control frequency change corresponds to a variation of the first signal representative of a temperature between a low threshold value (Tl) and a threshold value (T2) high. 6. Control device according to claim 4 or 5, characterized in that a hysteresis cycle for a control frequency change corresponds to a variation of the second signal representative of a voltage between a low threshold value (U1). and a high threshold value (U2). 7. Control device according to any one of claims 1 to 6, characterized in that it controls at least two stepper motors (31) each controlling the movement of a flap (2) movable. 8. Control device according to any one of claims 1 to 7, characterized in that it comprises at least one diode (D) freewheeling per phase of the stepper motor (31). 9. Control device according to any one of claims 1 to 8, characterized in that said first signal representative of a temperature corresponds to an estimate of the temperature near the stepper motor (31).