GB2332107A

GB2332107A - System for controlling the supply of an electric motor for driving a functional component of a motor vehicle

Info

Publication number: GB2332107A
Application number: GB9826513A
Authority: GB
Inventors: Philippe Pierre Marchal; Bruno Jean Guichard
Original assignee: ECIA Equipements et Composants pour lIndustrie Automobile SA
Current assignee: ECIA Equipements et Composants pour lIndustrie Automobile SA
Priority date: 1997-12-03
Filing date: 1998-12-02
Publication date: 1999-06-09
Anticipated expiration: 2018-12-02
Also published as: FR2771866A1; GB2332107A9; GB2332107B; GB9826513D0; FR2771866B1; DE19855424A1

Abstract

A system for controlling the supply of a motor 1, from a power supply source of the vehicle, is characterized in that it includes a pulse-width modulation chopper 7, which is interposed between the motor 1 and the supply source and whose operation is regulated by a square-wave drive signal, delivered by a controller 10, comprising a circuit 12 for generating an oscillating signal, means 13 for establishing a variable-amplitude control signal on the basis of control data 14 of the motor, which are associated with means such as a Zener diode for limiting the amplitude of this control signal to a value for safe operation of the motor, and a comparator 16 for comparing the oscillating signal and the control signal in order to establish the square-wave drive signal of the chopper 7. The motor may drive a fan of a cooling system of a vehicle.

Description

1 2332107 A r The present invention relates to a system for controlling

the supply of an electric motor for driving a functional component of a motor vehicle, from a power supply source of the vehicle.

Such a system may be applied to any DC electric motor fitted in a motor vehicle, for example a motorized fan unit associated with a radiator for cooling a coolant for.a motor vehicle engine.

By way of explanation, it is known that the engines of motor vehicles are usually associated with a cooling circuit through which a heat-exchange fluid flows, this fluid being made to flow through the engine, on the one hand, and through a radiator, on the other hand, in order to regulate its temperature.

In order to obtain sufficient heat exchange between the radiator and the surroundings, it is customary to associate one or more motorized fan units with this radiator, making it possible to create an air stream through this radiator.

In certain vehicles equipped with air conditioning systems, this or these motorized fan unit(s) are also designed to cool the air-conditioning condenser.

However, it is necessary to regulate the heat exchanges between the radiator and the surroundings of the vehicle in order to take account of various parameters connected with the operation of the vehicle, that is to say for example the target temperature of the air-conditioning system, the temperature of the engine, etc., in order to reduce the electrical power consumption and therefore the fuel consumption of the engine and the noise pollution caused by the operation of such motorized fan units.

Systems for controlling the operation of these motorized fan units with discrete speed changes have therefore been developed in the prior art.

For example, the prior art discloses control systems which make it possible to regulate the supply of these motorized fan units in order to obtain two - 2 different rotational speeds for them.

The operation of these motorized fan units is generally controlled by a computer for regulating the operation of the vehicle, which delivers control data to a system for driving the operation of the motorized fan units.

In the case when the radiator is associated, for example, with a single motorized fan unit, it is possible to control the rotational speed of this motorized fan unit by modifying the connection of its windings, or by connecting a resistor or the like in series with this motorized fan unit.

In the case when the radiator is associated with two motorized fan units, it is possible to obtain different rotational speeds for them by connecting them in series or in parallel.

These various operating modes of the or of each motorized fan unit are in general regulated by electromechanical relays opened or closed on the basis of the control data delivered by the computer for regulating the operation of the vehicle.

It will be understood, however, that there are a number of drawbacks with this.

Specifically, further to the fact that such control systems are bulky, the or each motorized fan unit needs to be designed so that it can withstand, without problems, the variations in supply voltage linked with the particular application in a motor vehicle and, in particular, the voltages which are much higher than its rated operating voltage, which means it has to be overengineered.

The object of the invention is therefore to solve these problems.

To this end, for controlling the driving a functional a power supply source that it includes a which is interposed the invention relates to a system supply of an electric motor for component of a motor vehicle, from of this vehicle, characterized in pulse-width modulation chopper, between the motor and the supply - 3 source and whose operation is regulated by a squarewave drive signal, delivered by control means, comprising means for generating an oscillating signal, means for establishing a variable-amplitude control signal on the basis of control data of the motor, which are associated with means for limiting the amplitude of this control signal to a value for safe operation of the motor, and means for comparing the oscillating signal and the control signal in order to establish the 10 square-wave drive signal of the chopper.

The invention will be understood more clearly with the aid of the following description which is given solely by way of example and refers to the appended drawings, in which:

- Fig. 1 illustrating embodiment of invention; and - Fig.

system.

To be precise, Figure 1 represents a system for controlling the supply of an electric motor for driving a functional component of a motor vehicle, denoted by the general reference 1, from a power supply source of the vehicle.

This motor is, for example, a motorized fan unit associated with a radiator for cooling an engine.

The supply terminals leading from the power supply source of the vehicle are, for example, denoted by the general references 2 and 3 in this figure, and correspond for example to the positive terminal of the supply and to the negative terminal of this supply, which. for example consists of the earth of the vehicle.

A freewheel diode, denoted by the general reference 4, is connected in parallel with the terminals of the motor.

Similarly, f iltering means of a conventional type, which are denoted by the general reference 5, are connected between the positive supply terminal of this represents a block diagram the structure of an illustrative a control system according to the 2 illustrates the operation of such a motor and earth.

This motor, this freewheel diode and these filtering means are connected, for example, to the cathode of a protective diode denoted by the general reference 6, the anode of which is connected to the positive terminal of the supply and which is intended to protect the rest of the circuits of this device against polarity reversal when this device is connected up to the supply source.

It will be readily apparent that this diode is not absolutely necessary.

The other supply terminal of the motor 1 is earthed through a pulse-width modulation chopper denoted by the general reference 7, this chopper being associated with current protection means, denoted by the general reference 8, and with thermal protection means denoted by the general reference 9, which are of conventional type and, for example, are integrated in this chopper. 20 It will therefore be seen that this pulse- width modulation chopper 7 is interposed between the motor 1 and the supply source of the motor, and that the operation of the latter is regulated by a square-wave drive signal delivered by control means denoted by the general reference 10 in this figure. These control means 10 are also connected to the power supply source of the vehicle and comprise controlled supply-input switching means, denoted by the general reference 11, interposed between the cathode of the protective diode 6, if the latter is provided, and the rest of the control means as will be described in more detail below, these controlled means 11 being closed when the control system according to the invention is activated.

The output of these control means 11 is connected to means 12 for generating an oscillating signal, and their input is connected to means 13 which are intended to establish a variable-amplitude control signal from control data 14 of the motor and are - associated with means 15 for limiting the amplitude of this control signal to a value for safe operation of the motor. The output of the means 11 is also connected to means 16 for comparing this oscillating signal and this control signal, and for establishing the squarewave drive signal for the chopper 7.

Specifically, the means 12 for generating the oscillating signal are designed to deliver to the comparison means 16, a reference signal oscillating between a low limit value and a high limit value, which are proportional to the supply voltage, while the establishing means 13 receive control data 14 of the motor coming, for example, from a computer for regulating the operation of the vehicle.

These data may, for example, be data of the binary type, for example carried on two data transmission wires, which the establishing means 13 convert into a control signal with amplitude proportional to the amplitude of the supply voltage, intended for the comparison means 16.

Thus, for example, on the basis of the control data 14, these means 13 deliver to the comparison means a signal whose amplitude is derived from the amplitude of the supply voltage of the power supply source of the vehicle, in order to make it possible to establish the square-wave drive signal of the chopper after comparison with the oscillating signal.

In the control system according to the invention, the output of the means 13 for establishing the control signal is associated, for example, with a capacitor 13a earthed, for example, in parallel with the means 15, which make it possible to smooth the variations in this signal in order to smooth the variations in the motor's operating noise.

In the control system according invention, the output to the of these means 13 for establishing the control signal is also associated with means 15 for limiting the amplitude of this control signal to a value for safe operation of the motor, 6 which may for example consist of a Zener diode for fixing this safety value.

The reason for this is that, as is known, the voltage of the power supply source in a motor vehicle can vary in amplitude to a relatively large extent, to reach a maximum voltage which is very much higher than its rated voltage.

It is therefore generally accepted, in the prior art, that the motors fitted in vehicles should be able to withstand such a maximum voltage without suffering damage.

By way of example, for a rated voltage of 13.5 volts, a maximum supply voltage equal to 18 volts may be mentioned.

There are, of course, a number of drawbacks with this because the motors therefore ought to be overengineered to withstand such voltages.

In the control system according to the invention, means are provided for limiting the amplitude of the control signal to a value for safe operation of the motor, so that it is no longer necessary to provide such overengineering of the motor, or the chopper.

This is because the use of these limiter means makes it possible to automatically limit the supply level of the motor to a safe value, as is illustrated in Figure 2.

Specifically, Figure 2 shows the output signal S12 of the means 12 for generating the oscillating signal, and the output signal S13 of the means 13 for establishing the control signal, these signals S12 and S13 being applied to the comparison means 16 in order to compare the oscillating signal and the control signal so as to establish the square-wave drive signal of the chopper, which is denoted by the reference S16 in this figure.

It will therefore be understood that, as the amplitude of the signal S13, established on the basis of the control data 14, becomes higher in comparison - 7 with the oscillating signal S12, the width of the pulses of the signal S16 increases in order to supply the motor with a high average voltage, and as the amplitude of the signal S13 decreases in comparison with the oscillating signal S12, the width of the pulses of the signal S16 decreases in order to supply the motor with a reduced average level.

The amplitude of the signal S13, established on the basis of the data 14, therefore makes it possible to adjust the supply and the rotational speed of the motor 1.

Furthermore, the means 15 for limiting the amplitude of the signal S13 make it possible to limit the supply of the motor to a level, denoted by the reference S15 in this Figure 2, which makes it possible to ensure automatic adjustment of the supply of the motor 1 when the supply voltage exceeds the value for safe operation of the motor, so that the average current flowing through the motor remains at a safe value.

It is therefore no longer necessary to overengineer the motor or the chopper so that they can withstand voltage peaks, since the control system according to the invention is provided with means making it possible to automatically limit the supply of the motor to its safe value.

By way of explanation, the means 12 generating the oscillating signal and the means 13 establishing the control signal being supplied with voltage of the power source, if the latter varies, amplitude of the signals S12 and S13 also varies, that if the amnlitude of the sianal S13 corresnonds for for the the so to supplying the motor with full voltage, the latter could then be supplied with a voltage very much higher than 35 its rated voltage.

If a Zener diode or another means for limiting the amplitude of this signal is used, independently of the amplitude of the supply voltage, the comparison means 16 will be able to automatically limit the 8 average supply current of the motor to a safe level, because in this case, as the supply voltage of the source increases, the amplitude of the oscillating signal S12 increases and the width of the pulses of the signal S16 is reduced, because the amplitude of the control signal S13 is limited to a maximum level S15.

In the example which has been described with reference to these figures, the means 13 for establishing the control signal include means for converting the control data 14 into a voltage signal whose amplitude is predetermined on the basis of the voltage of the supply source of the vehicle.

Thus, for example, on the basis of two binary data signals, it is in theory possible to define four supply levels for the motor and therefore four rotational speeds for it, in fact corresponding to a zero speed (stop) and three actual rotational speeds.

It will be readily apparent that a different number of signals may be used, as may a different number of supply levels for the motor.

As indicated above, the control system according to the invention also includes control means 11 for supply-input switching which are interposed between the supply source and the rest of the system.

The operation of these controlled means 11 may, for example, be driven by the establishing means 13 which receive the control data 14 of the motor in order to close these controlled means 11 only when the motor needs to be run, which makes it possible. to reduce the power consumption of this system by cutting its supply when it is not activated. This therefore makes it possible to avoid needlessly discharging the power supply source of the vehicle.

It will be readily apparent that various embodiments of this system may be envisaged, and that the various components involved in its construction may be integrated, for example, directly in the motor, for example on its brush-holder plate, so as to make it - 9 easier to integrate it into the motor vehicle.

There are furthermore a number of advantages with this, for example simplified cooling of power components of such a system, since they may be associated with cooling means, of a conventional type, placed for example in the air flow generated by the rotation of the motorized fan unit.

In addition, fitting such a circuit in proximity to the electric motor also makes it easier to filter the interference transmitted as a result of operating these components into the rest of the electrical circuits of the vehicle.

Quite clearly, it is possible to control the operation of motors other than a motorized fan unit by using such a system.

Claims

System for controlling the supply of an electric motor for driving a functional component of a motor vehicle, from a power supply source of this vehicle, characterized in that it includes a pulsewidth modulation chopper (7), which is interposed between the motor (1) and the supply source and whose operation is regulated by a square-wave drive signal (S16), delivered by control means (10), comprising means (12) for generating an oscillating signal (S12), means (13) for establishing a variable-amplitude control signal (S13) on the basis of control data (14) of the motor, which are associated with means (15) for limiting the amplitude of this control signal to a value (S15) for safe operation of the motor, and means (16) for comparing the oscillating signal and the control signal in order to establish the square-wave drive signal of the chopper (7).
2. System according to Claim 1, characterized in that the means (13) for establishing the control signal comprise means for converting the control data (14) into a voltage signal of predetermined amplitude from the power source of the vehicle.
3. System according to Claim 1 or 2, characterized in that the limiter means (15) comprise Zener diode means connected to the output of the establishing means (13).
4. System according to any one of the preceding 30 claims, characterized in that a capacitor (13a) is connected to the output of the establishing means (13) in order to smooth the control signal variations.
5. System according to any one of the preceding claims, characterized in that it includes controlled supply-input switching means (11) which are interposed between the supply source of the vehicle and the rest of this system and are closed at the instigation of the establishing means (13) on receipt of control data (14) of the motor.
6. System according to any one of the preceding claims, characterized in that the control data of the motor (14) are delivered by a computer for regulating the operation of the vehicle.
7. System according to any one of the preceding claims, characterized in that it is installed in the motor.
8. System according to Claim 7, characterized in that it is installed on the brush-holder plate of the motor.
9. A system for controlling the supply of an electric motor for driving a functional component of a motor vehicle as hereinbefore described and shown in the accompanying drawings.