JPH08251982A - Motor controller - Google Patents

Abstract

PURPOSE: To determine a locked state surely by setting the lock current of a DC motor accurately through a simple constitution. CONSTITUTION: A DC motor 1 for driving the window glass of automobile is connected with a drive circuit 2. Conduction current of the DC motor 1 is detected through a current detection resistor 5 and fed through an amplifier circuit 10 to a control circuit 15. When the DC motor 1 is conducted by delivering a driving signal to any one of transistors 6, 7, the control circuit 15 samples the motor current six times, for example, at a predetermined interval T2 during a period subsequent to a predetermined time T1 after conduction of the DC motor 1 when an inrush current is flowing and operates a threshold value Is for deciding the current lock based on the average value Iave of motor current. Since a threshold value including the variation elements of DC power supply voltage VB and ambient temperature Ta can be set, the lock current can be detected easily and surely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention energizes a direct current motor for driving a load in response to turning on of an operation switch,
The present invention relates to a motor control device that determines a lock state and performs stop control when the current value exceeds a lock current determination threshold value.

[0002]

2. Description of the Related Art For example, in a power window of an automobile, there is a power window in which a DC glass motor is moved up and down to utilize its rotational force. In this case, the manual mode is used to energize and rotate the DC motor to rotate the window glass while the switch is being operated, and the window switch is fully opened or closed by operating the operation switch with one touch. There is an automatic mode in which the DC motor is continuously energized until it is driven.

In this auto mode, the lock current of the DC motor is detected as a configuration for detecting whether the window glass is in the fully open state or the fully closed state. That is, when the window glass stops in the fully open state or the fully closed state, the rotation of the DC motor is also stopped, whereby the current rapidly increases and the lock current flows.

The lock current is detected by the current detecting means, and when the lock current continues for a predetermined time or longer, the energization of the DC motor is controlled to be stopped, so that the position where the windshield is stopped is surely detected. It is configured to stop the operation of the auto mode. As a result, the user can perform the one-touch operation when the window glass is fully opened or fully closed, and the operability can be improved without having to maintain the state in which the switch is operated.

[0005]

However, the conventional configuration as described above has the following problems when detecting the lock current of the DC motor. That is,
The value of the judgment current value for judging the lock current is set to a level that can be judged as the lock current in advance.
In some cases, the lock current cannot be reliably detected.

This is because, for example, the terminal voltage of the battery, which is the drive source of the DC motor, fluctuates according to the charging state,
Alternatively, according to the fluctuation of the ambient temperature, as shown in FIGS.
As shown in (4), the value of the lock current of the DC motor may fluctuate, so that if the detection level of the lock current is kept constant, it may not be possible to reliably detect the lock current.

Therefore, in the prior art, in order to set the optimum threshold value of the lock current, for example, a detection circuit for detecting the terminal voltage of the battery is provided, or a temperature detection circuit for detecting the temperature is provided to set the lock current. The threshold value for detection is set to an optimum value according to the state at that time.

However, since the voltage detection circuit and the temperature detection circuit are provided in order to set the threshold value to the optimum value as described above, the electrical configuration becomes very complicated and the cost becomes high. There is a defect.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a threshold value for determining a lock current of a DC motor while having a simple structure without a detection circuit for detecting a power supply voltage or ambient temperature. It is an object of the present invention to provide a motor control device in which the lock state can be accurately determined by reliably setting.

[0010]

According to the present invention, a DC motor for driving a load is energized in response to an ON operation of an operation switch, and when the current value exceeds a lock current determination threshold value. The present invention is intended for a motor control device that determines a lock state and performs stop control, and a current detection unit that detects a current flowing through the DC motor and a rush current when the DC motor is started. Calculating means for calculating the threshold value for detecting the lock current by means of calculation means, and the energizing current of the DC motor by the current detecting means exceeds the threshold value calculated by the calculating means. The present invention is characterized in that it is provided with control means for determining the locked state (invention of claim 1).

Further, it is preferable that the arithmetic means is configured to obtain the threshold value by calculating an average value of values obtained by sampling the inrush current of the DC motor at predetermined time intervals (claim 2). invention).

[0012]

According to the motor control device of the first aspect, when the DC motor is started, an inrush current flows at the time of starting, and the inrush current is detected by the current detecting means. become. The calculating means calculates and sets the threshold value for judging the lock current based on the detected current. This allows
The control means surely detects the lock state by stopping the DC motor by determining whether the lock current exceeds the threshold value for a predetermined time or longer when the DC motor is in the lock state. You will be able to control.

In this case, the inrush current at the time of starting the DC motor changes in accordance with the voltage fluctuation of the DC power supply which is supplying power and the fluctuation of the ambient temperature, like the lock current at the time of locking, so that the inrush current. By detecting, it becomes possible to set the threshold value including such fluctuation factors,
It is not necessary to provide a means for detecting the terminal voltage of the DC power supply or a means for detecting the ambient temperature, and it is not necessary to perform a complicated calculation from the detection results, and the lock state can be reliably detected as a simple and inexpensive structure. Will be able to do.

According to the motor control device of the second aspect,
Since the calculation means calculates the inrush current of the DC motor by averaging the sampled values, an accurate threshold value can be calculated from those average values even when the inrush current varies with time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a motor control device provided in a DC motor as a drive source for a power window of an automobile will be described below with reference to the drawings. In FIG. 1 showing the electrical configuration, a DC motor 1
Drives a drive mechanism as a load for moving the window glass up and down, and both terminals thereof are connected between output terminals of the drive circuit 2.

The drive circuit 2 comprises two relays 3 and 4 for switching the power supply to the DC motor 1. Relay 3,
The movable contacts of the contact parts 3a, 4a of 4 are connected between both terminals of the DC motor 1, and the normally open contacts of the contact parts 3a, 4a are both connected via a power supply line L to a vehicle battery (not shown) as a DC power supply. Further, the normally closed contacts of the contact portions 3a and 4a are both grounded via a current detection resistor 5 as current detection means. One terminal of each of the relay coils 3b and 4b is commonly connected to the power supply line L, and each of the other terminals is grounded through the npn-type transistors 6 and 7 for controlling energization. Further, flywheel diodes 8 and 9 are connected in parallel to the relay coils 3b and 4b, respectively.

The amplifier circuit 10 is a differential amplifier circuit which amplifies the detection output of the current detection resistor 5 and outputs it as a voltage signal.
The non-inverting input terminal is connected to the current detection resistor 5 via the resistor 11.
And the relays 3 and 4 are connected in common, and the inverting input terminal is connected to the ground side terminal of the current detection resistor 5 via the variable resistor 12. The output terminal of the amplifier circuit 10 is connected to the inverting input terminal via a parallel circuit including a resistor 13 and a capacitor 14.

The control circuit 15 having a function as a calculation means and a determination means is a microcomputer, RO
It is composed of M, RAM, etc., and is adapted to execute a threshold value setting program which will be described later to calculate and set a threshold value for lock current determination. The input terminal A of the control circuit 15 is connected to the output terminal of the amplifier circuit 10, the input terminal B is connected to the operation switch 16, and the output terminals C and D are connected.
Are connected to the bases of the above-mentioned transistors 6 and 7 via resistors 17 and 18, respectively.

The operation switch 16 is a switch that can be operated in accordance with the up and down movements of each window. There are two types of operation modes, a manual mode in which the window is moved up and down in the operating state, and an automatic mode in which one-touch operation is performed to fully open or fully close. The operation corresponding to the movement can be performed. In this auto mode, the fact that the window is in the fully open or fully closed state is determined by detecting the lock current flowing in the DC motor 1 in that state, and the energization is stopped.

Next, the operation of this embodiment will be described with reference to FIGS. 2 to 7 as well. When the operation switch 16 is operated in the manual mode, the DC motor 1 is operated in the operated state. A normal energizing operation is performed to move the window up and down. In the following description, an operation during the auto mode operation when the lock current is detected and the stop control is performed will be described.

First, when the automatic mode operation is performed by the operation switch 16, the control circuit 15 drives the DC motor 1 to either rotate forward or reverse to drive the window fully open or fully closed. The drive signal is output to the transistor 6 or 7. As a result, when the transistor 6 or 7 is turned on, either the relay coil 3b or 4b is energized and either the relay 3 or 4 is switched.

The DC motor 1 is energized in either direction from the DC power supply line L via the relays 3 and 4, and is normally or reversely driven. At this time, the value of the current I flowing through the DC motor 1 is detected as the voltage generated between the terminals due to the current flowing through the current detection resistor 5 interposed in series, and the amplifier circuit 1
0 inputs the current I of the DC motor 1 to the input terminal A of the control circuit 15 as the voltage signal Vamp.

The control circuit 15 executes the threshold value setting program shown in FIG. 2 immediately after outputting the drive signal as described above to set the threshold value for determining the lock current of the DC motor 1. become. That is, the control circuit 15
First waits for a fixed time T1 (for example, 5 ms) until the motor current I rises after the output of the drive signal (at time t0) (step S1), and then at a predetermined sampling time interval (for example, 3 ms) at time t1. The motor current Ix (x = 1, 2, ..., N) is detected as the voltage signal Vamp from to t6 (step S2). in this case,
The motor current Ix is detected 6 times as the number of times of sampling n, and thus the inrush current flowing when the DC motor 1 is started is detected (see FIG. 3).

Next, the control circuit 15 calculates the average value of the six sampled current values Ix (x = 1 to 6) as the current average value Iave according to the following equation (1), and thereafter,
The obtained current average value Iave is substituted into the equation (2) to calculate the lock current determination threshold value Is (step S3). The control circuit 15 sets the threshold value Is thus obtained as a determination value (step S
4) The program will be terminated.

[0025]

[Equation 1]

[Equation 2]

Thereafter, the control circuit 15 determines the DC motor 1 based on the detected voltage Vamp input from the amplifier circuit 10.
It is determined whether or not the motor current I flowing in the DC voltage exceeds the threshold value Is set as described above to determine the lock state of the DC motor 1. Then, the control circuit 15
When the motor current I exceeds the threshold value Is for a predetermined time (for example, 0.7 seconds) or more, the DC motor 1
When the lock state of is judged, the transistor 6 or 7
The drive signal that was being output to will be stopped and the power will be cut off. As a result, it is possible to stop the energization by detecting that the DC motor 1 is in the locked state by driving the window glass to the fully open or fully closed position.

Now, in the above-mentioned case, the value of the lock current of the DC motor 1 depends on the terminal voltage VB of the battery and the ambient temperature Ta.
However, as in the present embodiment, the DC motor 1
The threshold value Is for calculating the lock current is calculated and set from the inrush current that flows when the power is supplied to the device. Therefore, even if there is such a variable element, the lock is performed with an appropriate threshold value according to the situation at that time. The state can be determined.

Therefore, the result of an experiment conducted by the inventors of the present invention for setting the threshold value Is for determining the locked state by detecting the inrush current at the time of starting the DC motor 1 will be described. That is, FIG. 4 shows changes in the current from the start of the DC motor 1 to the time when the lock current flows and the stop control is performed. For example, even if the voltage VB of the battery is 10 V, the ambient temperature Ta remains unchanged. At -30 ℃ and 8
It can be seen that the inrush current and the lock current are different as in the case of 0 ° C.

In this case, the level of the inrush current and the level of the lock current change substantially in proportion to each other. Therefore, the threshold value for determining the lock current is set by detecting the inrush current. You can do it. In this way, by detecting the inrush current and setting the threshold value for the lock current determination, it is possible to automatically deal with the fluctuation of the power supply voltage VB and the fluctuation of the ambient temperature Ta.

FIG. 5 is a plot of the peak value of the inrush current of the DC motor 1 under various conditions. For example, the lock current value at normal temperature (plotted with Δ in the figure) starts at normal temperature. The results of measuring the peak value of the inrush current at various motor applied voltages are shown for the case of performing and the case of performing hot start.

The waveform of the inrush current may be two peaks as shown in FIG. 6 or only one peak as shown in FIG. 7 depending on the position of the rotor at the time of starting. . Therefore, in any of these cases, the average value of the inrush currents is calculated so that substantially the same inrush currents can be detected to reduce the difference between the two. Then, in this case, specifically, a substantial average value is obtained by sampling the current.

Actually, since a current flows after a certain delay time has elapsed after the drive signal for driving the DC motor 1 is output, as shown in the program, a predetermined waiting time T1 (for example, 5 ms). ), The current value for each sampling interval T2 (for example, 3 ms) is set to 6
The rush current Iave is obtained by detecting the number of times and calculating the average value thereof.

According to this embodiment, the rush current flowing through the motor at the time of starting the DC motor 1 is detected by the current detection resistor 5
Further, since the sampling circuit inputs by the amplifier circuit 10, the average is calculated by the control circuit 15, and the threshold value Is of the lock current is calculated and set based on the calculation result of the inrush current. The DC power supply voltage VB and the ambient temperature Ta, which are the factors that change the lock current value
Is not necessary to set the threshold value Is from them separately, the detection configuration is simplified, and the locked state of the DC motor 1 can be reliably determined.

In the above embodiment, the calculation formula for setting the threshold value is described using the formula (2). However, as shown below, a calculation formula such as the formula (3) is used. You may make it set a threshold value using. And
The contents of the calculation shown in the equation (3) are obtained by obtaining the corresponding lock current threshold value based on the measured data of the inrush current in the same manner as described above.

[0035]

(Equation 3)

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. The rush current may be detected by analog processing such as integration processing other than sampling. The present invention can be applied to a DC motor control device having a general configuration that performs stop control by detecting a lock current, in addition to a wind glass drive motor.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart of a threshold setting program.

FIG. 3 is an operation explanatory view showing sampling of a motor current.

FIG. 4 is a time chart of the motor current from the start of driving at different ambient temperatures.

FIG. 5 is a correlation diagram between the motor power supply voltage and the peak value of the inrush current.

FIG. 6 is a detection output waveform diagram of the motor inrush current (No. 1)

FIG. 7: Detection output waveform diagram of motor inrush current (Part 2)

FIG. 8 is a lock current characteristic diagram of a motor at different ambient temperatures and battery voltages.

[Explanation of symbols]

1 is a DC motor, 2 is a drive circuit, 3 and 4 are relays, 5 is a current detection resistor (current detection means), 6 and 7 are npn-type transistors, 8 and 9 are flywheel diodes, 10 is an amplification circuit, and 15 is Control circuit (calculation means, determination means), 1
Reference numeral 6 is an operation switch.

Claims (2)

[Claims] 1. A load control DC motor is energized in response to an ON operation of an operation switch, and when the current value exceeds a lock current determination threshold value, a lock state is determined and stop control is performed. In the motor control device configured to do so, a current detection unit that detects the energizing current of the DC motor, and an inrush current at the time of starting the DC motor are detected by the current detection unit to determine the lock current. And a determination unit for determining the locked state when the current supplied to the DC motor by the current detection unit exceeds the threshold value calculated by the calculation unit. A motor control device characterized by the above. 2. The calculating means is configured to calculate the threshold value by calculating an average value of values obtained by sampling the inrush current of the DC motor at predetermined time intervals. The motor control device according to item 1.