JP2023125367A - load drive device - Google Patents

Abstract

To provide a load drive device capable of more accurately detecting abnormality in a load.SOLUTION: A load drive device includes: a driver 10 having a drive terminal 10a for driving a load 2; a control unit 20 for controlling drive operation by the driver 10 by transmitting a drive control signal to the driver 10; and an abnormality detection line 30 for outputting an abnormality detection signal to the control unit 20 when an abnormality occurs in the load 2. When the drive terminal 10a becomes abnormal due to occurrence of an abnormality, the driver 10 stops the drive operation for a first period of time, and then performs driving again. The abnormality detection line 30 outputs the abnormality detection signal after delaying it by a second period of time longer than the first period of time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a load driving device.

As a conventional load driving device, a configuration shown in Patent Document 1 is disclosed. In this configuration, a load (1) supplied with power from a DC-DC converter (2) is driven by a load drive circuit (7). The load (1) performs a predetermined operation by being supplied with power.

JP2011-172426A

In a normal state, the load (1) performs a predetermined operation while consuming the supplied power as described above, but a short circuit or an open circuit may occur for some reason, and the load (1) may fall into a state where it cannot perform normal operations. However, Patent Document 1 does not disclose in detail the configuration for detecting such load abnormalities.

SUMMARY OF THE INVENTION An object of the present invention is to address the above-mentioned problems and provide a load drive device that can more accurately detect abnormalities in a load.

In order to achieve the above object, the load driving device according to the present invention includes:
a driver having a drive terminal for driving a load;
a control unit that controls a drive operation by the driver by transmitting a drive control signal to the driver;
and an abnormality detection line that outputs an abnormality detection signal to the control unit when an abnormality occurs in the load,
The driver stops the driving operation for a first period when the drive terminal becomes abnormal due to the occurrence of the abnormality, and then performs the driving again. The abnormality detection line receives the abnormality detection signal. , the output is delayed by a second period that is longer than the first period.

FIG. 1 is a diagram showing an electrical configuration of a load driving device in an embodiment of the present invention. The figure which shows the operation|movement of the load drive device 1 when the drive terminal 10a is in a normal state. The figure which shows the operation|movement of the load drive device 1 when the drive terminal 10a is in a drive state.

The load driving device of the present disclosure may be configured as in the embodiments shown below.

[First embodiment]
1-1. Explanation of configuration 1-2. Explanation of behavior [Modified example]

[First embodiment]
<1-1. Configuration explanation>
The load driving device 1 is configured as shown in FIG. 1, for example. The load drive device 1 is mounted on a moving body such as a vehicle, a ship, an aircraft, or a working machine. The load driving device 1 operates by receiving power from a power source, for example, and controls the power supply state (driving operation) for the connected load.

The load driving device 1 is electrically connected to a power source 3 via a load 2, and performs a driving operation so that the power source 3 starts supplying power to the load 2. Specifically, the load driving device 1 switches the current flowing from the power source 3 to the load 2. When the load driving device 1 performs a driving operation, a current flows through the load 2. That is, power is supplied to the load 2 from the power source 3.

For example, when the load driving device 1 performs a driving operation, the low voltage side terminal of the load 2 is connected to the ground with a relatively small impedance, so that current flows from the power source 3 to the load 2. When stopping the driving operation, the load driving device 1 puts the low voltage side terminal of the load 2 into a relatively high impedance state, so that no current flows from the power source 3 to the load 2.

The load 2 can be, for example, a speaker, a power device (transformer or relay), a light source (light emitting diode or light bulb), or the like. A battery or the like can be used as the power source 3. The power source 3 may be connected to the load 2 via various power devices such as a regulator and a transformer. The load 2 performs a predetermined operation depending on the supplied power.

The load drive device 1 may also serve as a display device provided in the moving body. A display device is a device that is connected to various electronic devices included in a mobile body and notifies a user of operating status information of the mobile body, entertainment information, and surrounding environment information outside the mobile body (road traffic information, etc.). The load drive device 1 also serves as a meter mounted on a vehicle, for example. The meter displays various information on various indicators (electronic displays and warning lights) in order to notify the user in response to input from measuring instruments and operating instruments provided in the vehicle.

The load drive device 1 includes a driver 10, a control section 20, and an abnormality detection line 30.

The driver 10 controls the power supply state to the electrically connected load based on the input drive control signal. The driver 10 is configured with a driver IC including, for example, a switch element, a delay circuit, an inverter circuit, and the like. That is, the driver 10 drives the load. In the present disclosure, the driver 10 has a drive terminal 10a, a drive control signal input terminal 10b, and a status signal output terminal 10c.

The drive terminal 10a is connected to the load 2 via a drive line Li, and controls the power supply state to the load 2 based on a drive control signal input from outside the driver 10. For example, in this embodiment, control is performed by adjusting the amount of current flowing to the load 2.

The drive control signal input terminal 10b is connected to the control unit 20, and is a terminal to which a drive control signal for determining whether or not the driver 10 performs a drive operation is input. For example, the drive control signal may be a pulse signal synchronized with the drive operation by the drive terminal. When the drive terminal performs PWM (pulse width modulation) control, the drive control signal may be a variable potential. The driver 10 may perform PWM control with a duty ratio according to this variable potential. The driver 10 may determine the degree of drive operation based on the drive control signal.

The status signal output terminal 10c is a terminal that is connected to the control unit 20 and outputs a status signal indicating the operating state of the drive terminal. The status signal output terminal 10c outputs a low signal if the state of the drive terminal 10a is normal, and a high signal if the state of the drive terminal 10a is abnormal. The status signal is input to the control section 20.

The driver 10 stops its driving operation while the status signal indicates an abnormal state. This operation prevents excessive current from occurring if, for example, a short circuit occurs in the load 2. Note that the driver 10 stops the driving operation for a predetermined period after detecting the abnormal state of the driving terminal 10a, and then performs the driving operation again. The period during which this driving operation is stopped is defined as a retry period (first period). The retry period has various cycles depending on the configuration of the driver, and the cycle may also vary for each trial.

The control unit 20 is composed of, for example, a microcontroller, and includes a CPU, memory (RAM, ROM), and the like. The CPU controls each part by reading and executing a program necessary for the operation of the load driving device 1 stored in advance in the ROM. In particular, the control unit 20 generates a drive control signal according to a predetermined program, and outputs the drive control signal to the drive control signal input terminal 10b of the driver 10.

It is preferable that the control unit 20 be able to detect any abnormality in the load 2 while controlling the driving operation of the driver 10 . Therefore, in the present disclosure, the control unit 20 receives a status signal indicating the operating state of the drive terminal 10a from the status signal output terminal 10c. The control unit 20 may detect an abnormality in the load 2 based on the status signal.

The abnormality detection line 30 is a signal line that connects one terminal to the drive line Li and the other terminal to the control unit 20. The abnormality detection line transmits an abnormality signal indicating that the drive line Li is abnormal to the abnormality detection signal input terminal 20a of the control unit 20.

When the potential of the drive line Li (drive terminal 10a) is abnormal, the abnormality detection line 30 delays the period (delay period, second period) longer than the cycle of the retry period and sends the abnormality detection signal to the control unit 20. and transmit. When the abnormality detection line 30 transmits the abnormality detection signal with a delay period, even if the status signal oscillates due to the retry operation of the driver 10, the abnormality detection signal will not oscillate and will accurately detect the abnormality occurring at the drive terminal 10a. can be transmitted to the control unit 20.
The detailed behavior of the anomaly detection line 30 is explained in Section 1-2.

The abnormality detection line 30 includes resistors 31, 32, 33, and 36, a diode 34, a capacitor 35, and a Schmitt trigger inverter 37.

The resistor 31 is a pull-down resistor with one terminal connected to the drive line Li and the other terminal connected to the case ground. Therefore, the resistance value is preferably relatively large, for example, about 100 kΩ. The resistor 31 pulls down the potential of the abnormality detection line 30 to ground when the drive line Li is open and the voltage is unstable.

The resistor 32 is a limiting resistor, and is, for example, about 10 kΩ. The resistor 32 prevents excessive current from flowing through the diode 34 and the capacitor 35, and slows down the charging and discharging of the capacitor 35.

The resistor 33 is a resistor that slows down the discharge of the capacitor 35, and has a resistance of about 100 kΩ, for example. That is, the resistor 33 is a discharge delay resistor.

The diode 34 is a charging-promoting rectifying element that prevents charging from slowing down due to current flowing to the resistor 33 when charging the capacitor 35.

The capacitor 35 is a capacitor provided so that the potential of the abnormality detection signal input terminal 20a lags with respect to a change in the state of the drive terminal 10a. The capacitance of the capacitor 35 is, for example, about 0.22 μF.

The resistor 36 is a limiting resistor and prevents a rush current from being input to the Schmitt trigger inverter 37. The resistance value of the resistor 36 is, for example, about 10 kΩ.

The Schmitt trigger inverter 37 is provided to input the potential whose fluctuation has been made gentle by the capacitor 35 to the microcomputer as a high or low digital value.

<1-2 Description of behavior>
The load driving device 1 configured as described in Section 1-1 operates as follows.

(Case A) When the load 2 is in a normal state The operation of the load driving device 1 when the load 2 is in a normal state will be described using FIG. 2. FIG. 2 includes four graphs, each of which shows the potential of the terminal corresponding to the symbol on the left as high (H) or low (L). The potential of the drive control signal input terminal 10b represents a drive control signal. The potential of the status signal output terminal 10c represents a status signal. The potential of the drive terminal 10a represents a drive signal. The potential of the abnormality detection signal input terminal 20a represents an abnormality detection signal.

(time t10)
Before the drive operation is started, the drive control signal is low. In this state, the driver 10 does not perform a driving operation and both terminals of the load 2 are at the same potential, so the driving signal also shows high. The abnormality detection line 30 shows a low level because the capacitor 35 becomes high upon being charged from the drive line Li, and then its value is inverted by the Schmitt trigger inverter 37.

(time t11)
Thereafter, the drive control signal rises to high to begin the drive operation.

(time t12)
The driver 10 switches the status signal and the drive signal in response to the rise of the drive control signal. A high status signal means that the driver 10 is performing a driving operation. The fact that the drive signal is low means that the load 2 is being driven.

(time t13)
Thereafter, the abnormality detection signal goes high with a delay of a second period. This is because the drive terminal 10a becomes low and the charge in the capacitor 35 is discharged toward the drive terminal 10a. The terminals of the discharged capacitor 35 indicate low, and the Schmitt trigger inverter 37 inverts the value so that it indicates high.

The control unit 20 determines that the drive terminal 10a and the load 2 are operating without abnormality when the drive signal is set to high and the abnormality detection signal becomes high after a predetermined time delay.

(Case B) When the load 2 is in an abnormal state The operation of the load driving device 1 when the load 2 is in an abnormal state (for example, short circuit) will be described using FIG. FIG. 3 shows potentials and signal states similar to those in FIG. 2.

(time t20)
Before the drive operation is started, the drive control signal is low. This state is no different from the state shown in FIG.

(time t21)
Thereafter, the drive control signal rises to high to begin the drive operation. The driver 10 then switches the status signal and drive signal in response to this rise. However, in this case, the potential of the drive signal remains high, unchanged from the potential of the power supply 3, since the load 2 is short-circuited. Note that if excessive current or unintended operation of the driver 10 occurs due to a short circuit, the drive signal will be in an unstable state although it is near high. Therefore, the state of the drive signal shown in FIG. 3 is just an example.

(time t22)
Thereafter, the driver 10 detecting that the drive signal does not go low sets the status signal, which means stopping the drive operation, to low. Thereafter, the drive operation is retried at the cycle of the first period.

(time t23)
In this case, since the drive line Li always indicates high, the abnormality detection line 30 continues to be charged and the abnormality detection signal remains low.

(time t24)
The control unit 20 determines that an abnormality has occurred in the drive terminal 10a when the abnormality detection signal does not become high even at time t24 when the second period has elapsed since the drive control signal was set high. do. In response to this, the control unit 20 desirably performs various protective operations, such as switching the drive operation signal output to the driver 10 to low, or terminating the operation of the connected electronic device.

When the control section 20 refers to the vibrating status signal to detect an abnormality, the timing of the vibration and the signal acquisition timing of the control section 20 do not match, and the state is not determined. However, as in this embodiment, when abnormality detection is performed based on the abnormality detection signal whose signal is stabilized by being delayed by the second period, it is difficult to be influenced by the signal acquisition timing of the control unit 20. Abnormality detection can be performed more accurately.

[Modified example]
Although the load driving device of the present invention has been explained using the configuration of the above-described embodiment as an example, the present invention is not limited to this, and other configurations may be used without departing from the gist of the present invention. Of course, various improvements and changes in display are possible within the scope.

An example in which the abnormality detection line 30 is configured as shown in FIG. 1 was shown. However, the configuration of the abnormality detection line 30 is not limited to this, and is configured to transmit the abnormality detection signal to the control unit 20 with a delay of a second period from the occurrence of an abnormality in the drive line Li (drive terminal 10a). That's fine.

A protection circuit or a protection electric element may be added to the load drive device 1 in order to improve resistance to known disturbances such as noise and surge.

Further, the true values of various signals of the driver 10 and the control unit 20 may be changed as appropriate depending on the circuit configuration, the IC used, and the like.

1 Load drive device 10 Driver 10a Drive terminal 10b Drive control signal input terminal 10c Status signal output terminal 20 Control section 20a Abnormality detection signal input terminal 30 Abnormality detection line 31, 32, 33, 36 Resistor 34 Diode 35 Capacitor 37 Schmitt trigger inverter

2 Load 3 Power supply

Claims (1)

a driver having a drive terminal for driving a load;
a control unit that controls a drive operation by the driver by transmitting a drive control signal to the driver;
and an abnormality detection line that outputs an abnormality detection signal to the control unit when an abnormality occurs in the load,
The driver stops the driving operation for a first period when the drive terminal becomes abnormal due to the occurrence of the abnormality, and then performs the driving again. The abnormality detection line receives the abnormality detection signal. , a load driving device that outputs the output after being delayed by a second period that is longer than the first period.

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