JPH0654591A - Apparatus for control of at least one electric load of vehicle - Google Patents

Abstract

PURPOSE: To provide a means which can perform satisfactory control of load, even when the value of variation for load control is small, in a device for controlling the electric load. CONSTITUTION: In a device for controlling the electric load 60 of a vehicle, especially, a stepping motor, a device 64 for detecting at least one variation which is adjusted to control the electric load 60, especially, the current flowing through the load 60 is provided. This device is provided with a control means 24 which operates, in accordance with the various operation patterns of the switching elements 38-44 of a bridge circuit 36, according to the values of these variations. When the current is large, the bridge circuit 36 is driven with a current application phase and a reflux phase. When the current is small, the reflux phase is omitted and it is driven with the two current application phases in a reverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling at least one electric load of a vehicle, and more particularly to a circuit arrangement consisting of at least four drivable elements forming a bridge circuit with at least one electric load. And a control means for actuating these elements, the device controlling at least one electrical load.

[0002]

2. Description of the Related Art An apparatus of this type is DE-OS371830.
Already known from 9. In this publication, it is proposed to control the electric load by a circuit device including four drivable elements that form a bridge circuit together with the electric load. In addition, control means are provided which operate the elements in pairs and so control the load. The actuation signal used here is in the form of a pulse, the load being regulated and controlled during the active phase of the signal. The drive period of the circuit arrangement or load is thereby divided into at least one energized phase and one so-called return phase. During these phases, each element is driven according to a predetermined, defined operating pattern. The energized phase is characterized by activating two diagonally opposed elements in the bridge, and the return phase is characterized by the operation of two opposed elements.

The circuit arrangement described above, the so-called switched H-bridge, has advantages in terms of energy savings, increased efficiency and generation of lost heat. The circuit arrangement is therefore particularly suitable for adjusting and positioning devices in vehicles, for example throttle valves which are moved by electric motors, in particular stepper motors. The variable regulated via the H-bridge controlling the load is ultimately the current flowing through the motor or motor winding. By controlling it open-loop or closed-loop, the device is adjusted or positioned.

In this case, as in the other use cases, there is a problem in closed loop control when the variable quantity is small.

From WO-A89 / 07859,
A means for finely controlling the position of a stepping motor within a range of one step is known by performing closed-loop control of a current flowing through a winding to a target value formed according to a desired position of the motor based on a characteristic curve.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is therefore to provide a means by which the load can be well controlled even when the variable adjusted to control the load is small in quantity (absolute value). It is to be.

[0007]

The problem is to detect at least one variable that is adjusted to control the load and, based on the value of this variable, set for each region of the value of the variable. It is solved by providing detection means and control means for actuating the elements in pairs according to the actuation pattern present.

[0008]

By using different actuation patterns for the elements of the bridge circuit, the advantage is obtained that the variable adjusted for controlling the load can always pass through zero. This gives good controllability and linearity of this variable directly even at small values.

Another advantage is that the configuration of the present invention is independent of device tolerances and thus alignment issues. As a result, the burden on the circuit technology can be kept very small.

Other advantages are apparent from the following description of the embodiments and the dependent claims.

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows a block circuit diagram of the control device 10. Reference numeral 12 denotes an arithmetic element (computer), to which the measured amount from the region of the vehicle or its drive unit (not shown in FIG. 1) corresponds via input leads 14 to 16. Measuring device 18
From 20.

The arithmetic element 12 is connected to the control means 24 via a connection line 22, and the control means is provided with a connection line 26 in addition to the connection line 22. The control means 24 has at least four output lines 28 to 34, which connect the control means 24 to a circuit arrangement 36, i.e. an H-bridge circuit.

The circuit arrangement 36 has at least four actuatable elements 38, 40, 42, 44. In that case, the output line 28 of the control means 24 is led to the element 42, the conductor 30 to the element 38, the conductor 32 to the element 40 and the conductor 34 to the element 44.

A conductor 48 is led from the positive pole 46 of the power supply voltage to the element 38 and in parallel to the element 42. A wire 50 connects the elements 38 and 40, and a wire 52 connects the elements 42 and 44 to each other. A conductor 54 is led from the element 44 to a negative pole 56 of the power supply voltage, and an element 40 in parallel with the element 44 is connected to the conductor 54. A so-called bridge diagonal is obtained between the conductors 50 and 52.

This bridge diagonal is formed from a conductor 58 leading from the conductor 50 to an electrical load 60, the load being conductor 6
It is connected via 2 to the measuring device 64. Measuring device 6
4 is further connected to a conductor wire 52 via a conductor wire 66. A measuring line 68 is led from the lead wire 62 to a differential amplifier 70, and the differential amplifier 70 is connected to the second input of the differential amplifier.
Is connected to the lead wire 52. The output line of the differential amplifier 70 controls the differential amplifier 70 by the control means 24.
The conductive wire 26 connected to

The actuatable elements 38 to 44 shown in FIG.
Are formed as MOS-FETs in the preferred embodiment. The controllable gate of this switching element is then connected to the conductors 28 to 34. The circuit means used to drive the elements 38 to 44 and / or feeding back the measured quantity from the area of the circuit arrangement 36 to the computing element 12 and analyzing the faults is not shown, but it will be understood by those skilled in the art. You can see that it is provided.

The load 60 is, in the preferred embodiment, the winding of a stepper motor which is associated with the throttle valve of an internal combustion engine of a motor vehicle. Corresponding configurations (control means and bridge circuit) are provided for the second and possibly other windings of the stepping motor.

Generally speaking, load 60 is an inductive element controlled by elements 38-44. In that case, the controlled variable is preferably the current flowing through the load, or a variable related to that current, such as the voltage value in the region of the load or bridge circuit, or the duration of the drive pulse when switching elements 38 to 44. is there. In the following, the current flowing through the load will be preferentially described as the controlled variable. However, it does not exclude other detectable variables.

The measuring device 64, which is preferably a measuring resistance, is connected to the connecting line between the load 60 and the conducting wire 52 and detects the value of the current flowing through the load. In other embodiments, this measured resistance can be placed on conductor 58, or conductor 54 or conductor 48 in the immediate vicinity of the supply voltage. However, special advantages are obtained in connection with the illustrated embodiment (or when arranged on the connecting line 58). This is because in that case a measurement result is obtained which directly represents the current flowing through the load.

The computing element 12 is a variable adjusted to control the load according to the operating variables supplied from the corresponding measuring devices 18 to 20 via the input lines 14 to 16,
It preferably forms a target value for the current flowing through the load.

In the use case of positioning a throttle valve of a vehicle in the field of electronic engine power control, the driving variables are in particular the position of the operating member (eg accelerator pedal) operable by the driver and the internal combustion engine and / or the vehicle. These are operational variables such as temperature, engine speed, throttle valve position, traveling speed, wheel speed, and transmission condition.

The arithmetic element 12 outputs a target value formed on the basis of a calculation formula, a characteristic curve or a characteristic value to the control means 24 via the lead wire 22. This target value is preferably an analog voltage or current value. However, in other embodiments it may be desirable to communicate the target value in digital form. However, in the following description, an analog target value on conductor 22 is assumed, without excluding other possibilities.

The control means 24 is the drive logic of the bridge circuit, for actuating the elements of the bridge circuit in pairs according to the measured values of the variables adjusted for the control of the load supplied via the conductor 26. A predetermined pattern is formed.

In other words, the elements are each actuated in pairs, in which case the choice of which elements are actuated in pairs is made according to the value of the variable detected by the measuring device 64, which is read via the lead 26. .

The electric load 60 can be energized in both directions by the bridge circuit 36. That is, the switch 38
By closing switches 44 and 44, current flows in one direction, and by closing switches 42 and 40 in the other.
In the preferred embodiment of throttle valve positioning, the throttle valve can be moved in the opening and closing directions by energizing in two directions. Furthermore, it should be noted that the throttle valve or motor is provided with a return member for safety reasons, ie a spring which biases the throttle valve to the closed position. Therefore, by appropriately energizing the windings of the motor or the stepping motor, the motor and the throttle valve can be held at predetermined positions.

Due to the restoring force, the bridge circuit 36 has been conventionally used.
Is controlled so that a time-limited energized phase occurs and energy is supplied to the load during that time. In that case, the duration of the energized phase is set according to the desired position. The bridge circuit is controlled so that the energy stored in the inductive load is removed except in the energized phase. This is called the reflux phase (freewheel phase).

Controlling the bridge circuit as described above is performed as follows in the embodiment shown in FIG. That is, it is performed by obtaining the period of the energized phase according to the deviation from the target amount of the actual amount in the method of performing the closed loop control of the variable adjusted by the control means 24 for controlling the load. In that case, during the period of the energized phase, the diagonally opposed elements (for example, 38 and 44 or 42 and 40) are actuated in accordance with the desired energization direction, while the energized phase is determined because the cycle length is fixed. In the reflux phase having a predetermined relationship with the period of, the opposing elements are activated (38 and 42 or 40 and 44). A predetermined operating pattern is thereby obtained.

By driving the bridge circuit as described above, the current flowing through the load is obtained on average, and the current determines the position to be finally adjusted.

When the energy stored in the load 60 is released, the current decay in the return phase is determined by the time constant of the circuit formed in the return phase. This is an unsatisfactory control characteristic in the region where the control amount is small in the known configuration, that is, in the region where the current flowing through the load 60 is small. This is because the average current flowing through the load becomes too large in quantity due to the relatively slow decay when the energized phase is minimal.

When controlling the load in the region where the current is small, it is necessary to make the conducting phase extremely short in the above method. However, this cannot be arbitrarily reduced by the switching time as compared with the fixed cycle length.
When the energized phase (switch-on period) is as short as possible, the current during reflux does not decay rapidly enough, so a quantitatively small current cannot be obtained.

Therefore, other actuation patterns are used in regions where the variables are small, that is, where the current is small. This means that diagonally opposed elements (eg 38 and 44) are activated during the first phase, while other diagonally opposed pairs of elements (e.g.
2 and 40) are activated. Therefore, in this case, switching is performed between the forward control and the reverse control. This makes it possible to obtain a quantitatively very small average current through the load. In that case, the throttle valve can be accurately positioned even in this driving state. In that case, in the preferred embodiment, the second phase is directly continuous to the first phase, and the sum of the periods of the two phases gives the predetermined set period length.

Particularly when using the stepping motor which is considered to be preferred, the configuration of the invention offers the advantage that the motor can be positioned in the vicinity of the one-step position when performing fine positioning.

According to the desired position, the arithmetic element 12 forms the stepping pulse according to the desired position for driving the stepping motor. This stepping pulse is converted into a current target value and transmitted to the control means 24 via the conductor 22. As a result, a stepwise energization of the winding is obtained during the rough step drive, and a corresponding phase-shifted energization (not shown) is applied to the second motor winding in opposition thereto. The motor is moved in structurally defined steps. Since the flowing current is large in quantity, the known actuation pattern described above is used.

In order to perform fine positioning within a structurally defined one-step range, the electronic arithmetic element 12 has a current characteristic that describes the relationship between the current flowing through the stepping motor winding and the desired position within the one-step range. Based on the curve, the target current value is likewise output via the conductor 22. The actual current value is supplied from the measuring device 64 via the conductor 26 to the control means 24. The individual current regions are obtained according to the detected current flowing through the load 60.

The control means then drives the bridge circuit via the output lines 28 to 34 according to a predetermined setpoint value and taking into account the various operating patterns mentioned above. The duration of the energized phase is then adjusted by closed-loop controlling the average actual current value to a predetermined target value.

As a result, the stepping motor or the throttle valve connected thereto is moved to a desired position.

In the preferred embodiment as shown in FIG. 3, three value regions are distinguished for the current. The maximum possible current through the load is + I in one control direction
max, and -Imax in the other control direction. In FIG.
An area C is shown which is bounded by two limit values I + and I-. In the preferred embodiment, this limit is approximately 10% of the maximum current value. There is a positive current region A and a negative current region B between the limit value and the maximum value.

Areas A to C according to the above-mentioned operation pattern
At 38, the elements 38 to 44 of the bridge circuit 36 are driven.

It is also possible to provide two limit values instead of one limit value for each current direction so that a hysteresis characteristic is produced. More preferably area C
Is set asymmetrically with respect to the zero point of the current.

FIG. 4 shows areas A (FIG. 4A) and B (FIG. 4A).
An example of the waveform of the current flowing through the load in (b)) is shown. In that case, the horizontal axis shows the time,
The vertical axis shows the measured value (current / voltage) detected by the measuring device 64. The drive signal of the bridge circuit formed by the closed loop function of the control means is a pulse-shaped signal having a variable pulse width (in the example of FIG. 4, pulse width T0) and a fixed cycle length T. This signal results in almost two drive phases (time domain up to T0, time domain between T0 and T, etc.).

In another embodiment, a driving signal having a fixed pulse width and a variable cycle length can be used.

Since the detected measured value is large in FIG. 4A, the control means 24 drives the bridge circuit in accordance with the operation pattern set for the area A. Thus, during the energizing phase (time to T0), the elements 38 and 44 are activated, while during the return phase (from T0 to T), the elements 38 and 42 or 40 and 44 are activated. In that case, a current waveform as shown in FIG. 4A is obtained. During the energizing phase, the current rises with a predetermined time constant, while during the return phase it decreases with a predetermined time constant. As a result, an average current (shown by a broken line) corresponding to the predetermined target value is obtained. Thereby the stepping motor can be adjusted as desired.

Similarly, FIG. 4B shows a current waveform relating to the region B of the detected measured value.
In the energized phase, the elements 42 and 40 are activated, and in the return phase, the elements 38 and 42 or 40 and 44 are activated.
The current rises with a predetermined time constant in the negative current value direction in the energized phase, and decreases in the positive current direction in the return phase. Then, a negative average current, that is, a current flowing through the load in the other direction with respect to the positive current defined in FIG. 4A is obtained.

FIG. 5 shows the current waveform in the area C. In the present embodiment, another operating pattern is selected that provides two energized phases approximately per cycle length.

What is characteristic here is that the reflux phase disappears, and the energized phase in the backward direction is directly continuous with the energized phase in the forward direction (or vice versa). In that case, the period of the first energized phase is determined by the length of the pulse width of the drive signal.

FIG. 5 (a) shows a current waveform that produces a positive average current, FIG. 5 (b) shows a current waveform when the average current is 0, and FIG. 5 (c) further shows. The waveform of the negative average current, ie the current flowing through the load in the opposite direction to that shown in FIG.

The actuation pattern is set so that elements 38 and 44 are actuated in the region up to T0. This increases the current flowing through the load in the direction of elements 38 to 44 in the illustrated embodiment. At time T0, elements 42 and 40 are activated and elements 38 and 44 are turned off. A waveform of the current flowing through the load from the element 42 to the element 40 is thereby obtained, which is shown in FIG. After one cycle, elements 38 and 44 are activated again at time T0.

In time averaging, an average current (indicated by the broken line) is obtained which corresponds to the target value set by the electronic computing element and which positions the stepping motor and thus the throttle valve accordingly.

When MOS-FET transistors are used as elements 38-44, actuation means "conducting" the transistors, that is, switching them on.

The process described above is carried out in the control means 24.

FIG. 2 shows a block circuit diagram of an embodiment of the control means 24 which has proved to be preferred in the embodiment. The elements already described and described in FIG. 1 bear the same reference numerals in FIG. 2 and will not be described further.

The measured value of the current flowing through the load, which is supplied via the conductor 26, is supplied to the comparison point 100. A similar conducting wire 22 is led to this comparison point, and a current target value is supplied from the arithmetic element 12 onto this conducting wire 22. Conductor 10
By means of 2, the comparison point 100 is preferably connected to a closed loop controller having an integral element (integral component) 104. The output line 106 of the controller is led to a second comparison point 108. From the signal generator 112 to the other lead 1 at the second comparison point.
10 has been introduced. Output line 11 of second comparison point 108
4 is led to the comparator 116. The output line 118 of the comparator causes the comparator 116 to operate the logic circuit 1.
It is connected with 20. The output lines of the logic circuit 120 form the output lines 28 to 34 of the control means 23.

The device described above provides a closed loop control of the variable, preferably the current flowing through the load, which is adjusted for the control of the load. In that case, the comparison point 10
A control deviation is formed by the comparison of the target value and the actual value at 0, which control deviation is provided via the conductor 102 to the controller 1
04 is supplied. The controller produces an output signal according to the magnitude of the control deviation and outputs it as a voltage level (positive or negative level, respectively depending on the required current direction) via conductor 106 to a second comparison point 108.

Therefore, a pulsed drive signal having a fixed cycle length and a variable pulse width is formed in relation to the comparator 116. In that case, the cycle length depends on the signal generator 1.
12 is set. The output signal of the signal generator has a triangular or sawtooth curve and is compared at a comparison point 108 with a predetermined voltage level on conductor 106. The signal supplied from the signal generator 112 onto the conductor 110 is the conductor 1
Above or below the voltage level above 06, the output signal of comparator 116 on lead 118 will change in signal level. According to the magnitude of the voltage level which is the output signal of the controller 104, the logic circuit 120
Is supplied with a pulse-shaped signal having a variable pulse duty ratio and a fixed period length, and the pulse length is a value representing a control deviation, and thus a current value required to obtain a desired position. .

The logic circuit 120 converts this drive signal formed by the controller into an actuation signal according to the actuation pattern set for the corresponding area, and this actuation signal is output via the output lines 28 to 34 to the bridge circuit 36. Output to.

In addition to the above-mentioned closed-loop control with the I component, it is also possible, preferably or additionally, to carry out closed-loop control with only proportional and / or derivative components. Furthermore, it is also possible to use other control methods.

In that case, the frequency of the signal generator is chosen such that it is at least greater than the frequency of the stepping pulses in the rough step drive.

The operation pattern is selected by the following device. The conductive wire 26 is connected to the filter 1 via the conductive wire 122.
24, preferably a low pass filter. The output line 126 of the filter has a comparison point 128 and another comparison point 13
It is led to 0. The comparison point 128 is supplied via the conductor 132 with a positive range limit value I + from the memory means 134, whereas the comparison point 130 is supplied via the conductor line 136 with a negative limit value I− from the memory means 138. . Comparison point 12
8 is led to the comparator 142 having hysteresis, and the output signal 144 of the comparator is
Are supplied to the logic circuit 120. Similarly, comparison point 13
The output line 146 of 0 is led to the comparator 148 having hysteresis, and the output line 150 of the comparator 148 is led to the logic circuit 120.

The configuration of 128 to 150 selects the current regions A, B and C and thus the operating pattern in the logic circuit 120. If the filtered detection quantity is below or above one of the limit values (I +, I-), the output signal of the respective comparator changes. From the combination of output signals, the logic circuit 120 identifies each signal region and selects the activation pattern accordingly.

In that case, the logic circuit 120 is formed from logic elements, each logic element comprising conductors 118, 144 and 15.
Based on the signal level provided through 0, the output line that activates the elements of the bridge circuit 36 is selected according to the above description.

The logic circuit must be designed according to the output stage used and the drive signal required for it.

In this embodiment, the logic circuit is a C-MOS.
It could be realized by combining NAND gates.

It is also used to control a diesel injection pump, which preferably positions the control rod.
Furthermore, the above-described structure can be preferably used anywhere where at least the current flowing through the inductive load must be switched and controlled in a region where the current is small. The method described above can also be effectively used in connection with other drive concepts such as electric engines.

The circuit means shown in FIG. 2 can be realized by analog, digital or hybrid circuit technology.

[0066]

As is apparent from the above description, according to the present invention, in a device for controlling an electric load, satisfactory load control can be performed even if the variable for controlling the load is small in quantity. it can.

[Brief description of drawings]

FIG. 1 is a schematic block circuit diagram of a controller for controlling at least one load.

FIG. 2 is a block circuit diagram of control means for controlling the elements of the bridge circuit.

FIG. 3 is an explanatory diagram showing a range of variable values adjusted to control a load.

FIG. 4A and FIG. 4B are signal waveform diagrams of the current when the control current is large.

5 (a), (b) and (c) are signal waveform diagrams of a current when the control current is small.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 control device 12 arithmetic element 18, 20 measuring device 24 control means 36 circuit device

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Klaus Müller Germany 7144 Asperk Eberhardstraße 15

Claims (10)

[Claims] 1. At least one circuit arrangement comprising at least four drivable elements forming a bridge circuit with at least one electrical load, and control means for operating these elements.
In a device for controlling one electrical load, at least one measuring device for detecting at least one variable adjusted for controlling the load is provided, said control means according to an actuation pattern based on the detected variable and said element A device for controlling at least one electrical load, characterized in that different actuation patterns are provided for regions of different values of the variable. 2. The electric load is preferably a winding of a stepping motor which is used in the area of electronic engine power control of an internal combustion engine to regulate and position the elements defining the power output. Equipment. 3. Device according to claim 1, characterized in that the detected characteristic variable is indicative of the value of the current flowing through the load. 4. The device according to claim 1, wherein the control of the load takes place during a predetermined period divided into at least two phases. 5. In the range of the value of the detected variable having a quantitatively small value, two diagonally opposed elements of the bridge circuit are activated in the first phase, and the second element is activated.
5. Device according to claim 1, characterized in that in the phase (2) the other two diagonally opposite elements are activated. 6. In the region where the variable has a value having a large quantitative value, in the first phase, that is, the energized phase, two elements that are diagonally opposed to each other according to the control direction, and the second phase, That is, in the reflux phase, two elements facing each other are actuated, the device as claimed in claim 1. 7. A calculation element obtains a target value of the variable corresponding to a desired position from the detected operating variable, and the variable is adjusted by a control circuit for closed loop control of an actual value to the target value, in which case the variable 7. Device according to claim 1, characterized in that a pulsed drive signal having a pulse width and a fixed period length is generated. 8. A method for detecting a variable representing a current flowing through a load,
Device according to any one of the preceding claims, characterized in that it is performed by means of measuring resistors arranged diagonally to the bridge. 9. The target value is set so as to obtain a rough step drive and a fine adjustment of a stepping motor.
The device according to paragraph. 10. A circuit device comprising a computing element, at least four drivable elements forming a bridge circuit together with at least one electric load, and control means for activating these elements, wherein two loads are controlled. A device for controlling at least one electrical load, which is controllable in a direction, wherein at least one measuring device for detecting at least one variable adjusted for controlling at least one electrical load is provided, Control of at least one electrical load, characterized in that, when the value of is quantitatively small, control is performed alternately in one direction and in the other direction in order to adjust on average to the value of the set variable. apparatus.