阅读说明：本技术 脉冲宽度调制信号生成装置及其异常状态检测方法 (Pulse width modulation signal generating device and abnormal state detecting method thereof ) 是由 段飞虎 于 2018-07-05 设计创作，主要内容包括：本发明提供脉冲宽度调制信号生成装置及其异常状态检测方法。脉冲宽度调制信号生成装置将生成的第一脉冲宽度调制信号经由脉冲宽度调制信号线传输至外部的电子装置,其特征在于还具有：脉冲宽度调制信号提取部,从电子装置提取第一脉冲宽度调制信号的振幅及/或相位被变更而成的第二脉冲宽度调制信号；脉冲宽度调制信号转换部,将第二脉冲宽度调制信号从数字信号转换为模拟信号；以及异常检测部,基于第二脉冲宽度调制信号被转换为模拟信号而得到的数值,检测脉冲宽度调制信号线的异常状态。由此,不需要使用复杂的数字逻辑电路和判断逻辑,能够以简洁的电路结构来明确地检测脉冲宽度调制信号线的异常状态。(The invention provides a pulse width modulation signal generating apparatus and an abnormal state detecting method thereof. The pulse width modulation signal generation device transmits the generated first pulse width modulation signal to an external electronic device via a pulse width modulation signal line, and is characterized by further comprising: a pulse width modulation signal extraction unit that extracts a second pulse width modulation signal in which the amplitude and/or phase of the first pulse width modulation signal is changed, from the electronic device; a pulse width modulation signal conversion unit that converts the second pulse width modulation signal from a digital signal to an analog signal; and an abnormality detection unit that detects an abnormal state of the pulse width modulation signal line based on a value obtained by converting the second pulse width modulation signal into an analog signal. Thus, it is possible to clearly detect an abnormal state of the pulse width modulation signal line with a simple circuit configuration without using a complicated digital logic circuit and determination logic.)

1. A pulse width modulation signal generation apparatus has:

a pulse width modulation signal generation unit that generates a first pulse width modulation signal as a digital signal; and

a pulse width modulation signal transmission unit configured to transmit the first pulse width modulation signal to an external electronic device via a pulse width modulation signal line;

the pulse width modulation signal generation device is characterized by further comprising:

a pulse width modulation signal extraction unit that extracts a second pulse width modulation signal from the electronic device, the second pulse width modulation signal being a pulse width modulation signal in which an amplitude and/or a phase of the first pulse width modulation signal is changed;

a pulse width modulation signal conversion unit that converts the second pulse width modulation signal from a digital signal to an analog signal; and

and an abnormality detection unit that detects an abnormal state of the pulse width modulation signal line based on a value obtained by converting the second pulse width modulation signal into an analog signal.

2. The pulse width modulated signal generating apparatus of claim 1,

the pulse width modulation signal conversion section includes:

a first conversion circuit that converts the second pulse width modulation signal from a digital signal to a first analog signal reflecting a duty ratio of the second pulse width modulation signal; and

a second conversion circuit that converts the second pulse width modulation signal from a digital signal to a second analog signal reflecting a peak voltage of the second pulse width modulation signal;

the abnormality detection unit detects an abnormal state of the pulse width modulation signal line based on a voltage value of the first analog signal and a voltage value of the second analog signal.

3. The pulse width modulated signal generating apparatus of claim 2,

the abnormality detection unit detects whether the pulse width modulation signal line is in a ground short-circuit abnormal state in which the pulse width modulation signal line is short-circuited to ground or a power supply short-circuit abnormal state in which the pulse width modulation signal line is short-circuited to battery power supply of the electronic device, based on a voltage value of the first analog signal;

the abnormality detection unit detects whether the pulse width modulation signal line is in an abnormal open circuit state or a normal connection state in which the pulse width modulation signal line is open, based on the voltage value of the first analog signal and the voltage value of the second analog signal.

4. The pulse width modulation signal generating apparatus according to claim 2 or 3,

the first conversion circuit includes:

a first input terminal to which the second pwm signal is input, the first input terminal being connected to the pwm signal extraction unit;

a constant voltage power supply that outputs a constant voltage lower than an output voltage of a battery power supply of the electronic device;

the first RC filter circuit performs low-pass filtering processing;

a switching transistor connected between the constant voltage power supply and the first RC filter circuit, and turning on or off the constant voltage power supply and the first RC filter circuit by using the second pulse width modulation signal inputted from the first input terminal as a control signal;

a first voltage division circuit that divides the signal filtered by the first RC filter circuit; and

and a first output terminal that outputs a signal divided by the first voltage dividing circuit as the first analog signal.

5. The pulse width modulated signal generating apparatus of claim 4,

the second conversion circuit includes:

a second input terminal connected to the pwm signal extraction unit and the first input terminal;

a rectifier circuit that rectifies a signal input from the second input terminal;

the second RC filter circuit is used for carrying out low-pass filtering processing on the signal rectified by the rectifying circuit;

a second voltage division circuit that divides the signal filtered by the second RC filter circuit; and

and a second output terminal that outputs the signal divided by the second voltage dividing circuit as the second analog signal.

6. The pulse width modulated signal generating apparatus of claim 5,

the switching transistor turns on between the constant voltage power supply and the first RC filter circuit when the second pulse width modulation signal input from the first input terminal is at a low level,

the abnormality detection unit detects that the pulse width modulation signal line is short-circuited to ground when a voltage value of the first analog signal is equal to or higher than a first threshold value set to be lower than a voltage value of an output voltage value of a constant voltage power supply of the first conversion circuit divided by the first voltage dividing circuit;

the abnormality detection unit detects that the pulse width modulation signal line is short-circuited with respect to a battery power supply of the electronic device when a voltage value of the first analog signal is equal to or lower than a second threshold set lower than the first threshold and higher than 0V;

the abnormality detection unit detects that the pulse width modulation signal line is open if the voltage value of the second analog signal is equal to or less than a predetermined third threshold value when the voltage value of the first analog signal is lower than the first threshold value and higher than the second threshold value, and detects that the pulse width modulation signal line is in a normally connected state if the voltage value of the second analog signal is higher than the third threshold value.

7. An abnormal state detection method performed by a pulse width modulation signal generation apparatus having:

a pulse width modulation signal generation unit that generates a first pulse width modulation signal as a digital signal; and

a pulse width modulation signal transmission unit configured to transmit the first pulse width modulation signal to an external electronic device via a pulse width modulation signal line;

the abnormal state detection method is characterized by comprising the following steps:

a pulse width modulation signal extraction step of extracting a second pulse width modulation signal from the electronic device, the second pulse width modulation signal being a pulse width modulation signal in which an amplitude and/or a phase of the first pulse width modulation signal is changed;

a pulse width modulation signal conversion step of converting the second pulse width modulation signal from a digital signal to an analog signal; and

an abnormality detecting step of detecting an abnormal state of the pulse width modulation signal line based on a value obtained by converting the second pulse width modulation signal into an analog signal.

8. The abnormal state detection method according to claim 7,

in the pulse width modulation signal conversion step, the second pulse width modulation signal is converted from a digital signal to a first analog signal reflecting a duty ratio of the second pulse width modulation signal, and the second pulse width modulation signal is converted from a digital signal to a second analog signal reflecting a peak voltage of the second pulse width modulation signal,

in the abnormality detecting step, it is detected whether the pulse width modulation signal line is in a short-to-ground abnormal state in which the pulse width modulation signal line is short-circuited to ground or in a short-circuit abnormal state in which the power supply to the battery of the electronic device is short-circuited based on the voltage value of the first analog signal, and whether the pulse width modulation signal line is in an open circuit abnormal state in which the pulse width modulation signal line is open circuit or in a normal connection state based on the voltage value of the first analog signal and the voltage value of the second analog signal.

9. The abnormal state detection method according to claim 8,

the abnormality detecting step includes:

a power supply short-circuit detection step of detecting whether or not the pulse width modulation signal line is in a power supply short-circuit abnormal state with respect to a battery power supply short-circuit of the electronic device, based on a voltage value of the first analog signal;

a ground short detection step of detecting whether or not the pulse width modulation signal line is in a ground short abnormal state in which the power supply is short-circuited to ground based on a voltage value of the first analog signal when the power supply short detection step detects that the power supply is not in the power supply short abnormal state;

a disconnection detecting step of detecting whether or not the pulse width modulation signal line is in a disconnection abnormal state of disconnection based on a voltage value of the second analog signal when the ground short circuit detecting step detects that the pulse width modulation signal line is not in the ground short circuit abnormal state; and

a normal connection determination step of determining that the pulse width modulation signal line is in a normal connection state when the disconnection detection step detects that the disconnection abnormality state is not present.

Technical Field

The present invention relates to a pulse width modulation signal generating device and an abnormal state detecting method thereof, and more particularly, to a pulse width modulation signal generating device and an abnormal state detecting method thereof for detecting an abnormal state of a pulse width modulation signal line when a pulse width modulation signal is transmitted to an external device.

Background

Currently, various electronic devices such as in-vehicle devices are controlled by a pulse width modulation signal (PWM signal). The pulse width modulation signal generating device generates a pulse width modulation signal as a digital signal by a microprocessor, for example, and controls a motor of an electronic device.

In the control using the pulse width modulation signal, if an abnormal state occurs in a pulse width modulation signal line between the pulse width modulation signal generation device and the electronic device to be controlled, the electronic device cannot be normally controlled. Therefore, it is necessary to detect an abnormal state of the pwm signal line.

Conventionally, a monitoring circuit has been proposed which detects an abnormal state of a pulse width modulation signal line by a digital circuit including a logic gate, a comparator, and the like. In the digital circuit-based monitor circuit, a monitor point is set, and an abnormal state of the pwm signal line is detected based on a high-low logic state of a potential of the monitor point.

However, there is a possibility that a plurality of different abnormal states may occur in the pwm signal line between the pwm signal generating apparatus and the electronic apparatus to be controlled. For example, the pwm signal line may be shorted to ground, shorted to battery power, open, etc. If the high-low logic state of the potential is detected only after the pulse width modulation signal is output, the above-described plurality of different abnormal states cannot be distinguished. Furthermore, if the above-described plurality of different abnormal states are to be distinguished by a monitoring circuit based on a digital circuit, a complicated logic circuit and a plurality of monitoring points need to be designed, which increases the circuit scale and increases the cost.

Disclosure of Invention

In view of the above-described problems of the prior art, it is an object of the present invention to provide a pwm signal generating apparatus and an abnormal state detecting method thereof, which can clearly detect an abnormal state of a pwm signal line with a simple circuit configuration.

An embodiment of the present invention provides a pulse width modulation signal generation device including: a pulse width modulation signal generation unit that generates a first pulse width modulation signal as a digital signal; and a pulse width modulation signal transmission unit that transmits the first pulse width modulation signal to an external electronic device via a pulse width modulation signal line; the pulse width modulation signal generation device is characterized by further comprising: a pulse width modulation signal extraction unit that extracts a second pulse width modulation signal from the electronic device, the second pulse width modulation signal being a pulse width modulation signal in which an amplitude and/or a phase of the first pulse width modulation signal is changed; a pulse width modulation signal conversion unit that converts the second pulse width modulation signal from a digital signal to an analog signal; and an abnormality detection unit that detects an abnormal state of the pulse width modulation signal line based on a value obtained by converting the second pulse width modulation signal into an analog signal.

Thus, it is possible to clearly detect an abnormal state of the pwm signal line connecting the pwm signal generating apparatus and the electronic apparatus with a simple circuit configuration without using a complicated digital logic circuit and determination logic.

In the above-described pulse width modulation signal generation device, the pulse width modulation signal conversion unit may include: a first conversion circuit that converts the second pulse width modulation signal from a digital signal to a first analog signal reflecting a duty ratio of the second pulse width modulation signal; and a second conversion circuit that converts the second pulse width modulation signal from a digital signal to a second analog signal reflecting a peak voltage of the second pulse width modulation signal; the abnormality detection unit detects an abnormal state of the pulse width modulation signal line based on a voltage value of the first analog signal and a voltage value of the second analog signal.

Thus, by generating a plurality of analog signals reflecting the duty ratio and the peak voltage of the second pulse width modulation signal extracted from the electronic device, it is possible to more reliably detect a plurality of abnormal states of the pulse width modulation signal line.

In the above-described pulse-width-modulated-signal generating device, the abnormality detecting unit may detect whether or not the pulse-width-modulated signal line is in a ground short-circuit abnormal state in which the pulse-width-modulated signal line is short-circuited to ground, or a power supply short-circuit abnormal state in which the pulse-width-modulated signal line is short-circuited to a battery power supply of the electronic device, based on a voltage value of the first analog signal; the abnormality detection unit detects whether the pulse width modulation signal line is in an abnormal open circuit state or a normal connection state in which the pulse width modulation signal line is open, based on the voltage value of the first analog signal and the voltage value of the second analog signal.

Thus, by combining and determining the voltage values of the plurality of analog signals reflecting the duty ratio and the peak voltage of the second pulse width modulation signal extracted from the electronic device, it is possible to reliably detect a plurality of types of abnormal states such as a short-circuit state and a disconnection state of the pulse width modulation signal line.

In the above-described pwm signal generation apparatus, the first conversion circuit may include: a first input terminal to which the second pwm signal is input, the first input terminal being connected to the pwm signal extraction unit; a constant voltage power supply that outputs a constant voltage lower than an output voltage of a battery power supply of the electronic device; the first RC filter circuit performs low-pass filtering processing; a switching transistor connected between the constant voltage power supply and the first RC filter circuit, and turning on or off the constant voltage power supply and the first RC filter circuit by using the second pulse width modulation signal inputted from the first input terminal as a control signal; a first voltage division circuit that divides the signal filtered by the first RC filter circuit; and a first output terminal that outputs a signal divided by the first voltage dividing circuit as the first analog signal.

In the above-described pulse width modulation signal generating apparatus, the second conversion circuit may include: a second input terminal connected to the pwm signal extraction unit and the first input terminal; a rectifier circuit that rectifies a signal input from the second input terminal; the second RC filter circuit is used for carrying out low-pass filtering processing on the signal rectified by the rectifying circuit; a second voltage division circuit that divides the signal filtered by the second RC filter circuit; and a second output terminal that outputs a signal divided by the second voltage dividing circuit as the second analog signal.

In the pwm signal generation apparatus, the switching transistor may be configured to turn on the constant voltage power supply and the first RC filter circuit when the second pwm signal input from the first input terminal is at a low level, and the abnormality detector may be configured to detect that the pwm signal line is short-circuited to ground when a voltage value of the first analog signal is equal to or higher than a first threshold value set to be lower than a voltage value obtained by dividing an output voltage value of the constant voltage power supply of the first converter circuit by the first voltage divider circuit; the abnormality detection unit detects that the pulse width modulation signal line is short-circuited with respect to a battery power supply of the electronic device when a voltage value of the first analog signal is equal to or lower than a second threshold set lower than the first threshold and higher than 0V; the abnormality detection unit detects that the pulse width modulation signal line is open if the voltage value of the second analog signal is equal to or less than a predetermined third threshold value when the voltage value of the first analog signal is lower than the first threshold value and higher than the second threshold value, and detects that the pulse width modulation signal line is in a normally connected state if the voltage value of the second analog signal is higher than the third threshold value.

In this way, by combining the analog circuit configurations of the pwm signal generator, the first converter circuit, and the second converter circuit, these circuits are interlocked with each other, so that the ground short-circuit abnormal state and the power short-circuit abnormal state of the pwm signal line can be reliably detected, and the open circuit abnormal state and the normal connection state of the pwm signal line can be distinguished.

An embodiment of the present invention also provides an abnormal state detection method performed by a pulse width modulation signal generation apparatus having: a pulse width modulation signal generation unit that generates a first pulse width modulation signal as a digital signal; and a pulse width modulation signal transmission unit that transmits the first pulse width modulation signal to an external electronic device via a pulse width modulation signal line; the abnormal state detection method is characterized by comprising the following steps: a pulse width modulation signal extraction step of extracting a second pulse width modulation signal from the electronic device, the second pulse width modulation signal being a pulse width modulation signal in which an amplitude and/or a phase of the first pulse width modulation signal is changed; a pulse width modulation signal conversion step of converting the second pulse width modulation signal from a digital signal to an analog signal; and an abnormality detection step of detecting an abnormal state of the pulse width modulation signal line based on a value obtained by converting the second pulse width modulation signal into an analog signal.

The above-described various aspects of the pulse width modulation signal generation device of the present invention can be applied to the abnormal state detection method, the abnormal state detection program, and the recording medium on which the abnormal state detection program is recorded of the present invention, and the corresponding technical effects are obtained.

Drawings

Fig. 1 is a block diagram showing a configuration of a pulse width modulation signal generating apparatus according to a first embodiment of the present invention.

Fig. 2 is a circuit block diagram showing a partial circuit configuration in the pulse width modulation signal generation device according to a specific example of the first embodiment of the present invention.

Fig. 3 is a signal waveform diagram of a specific example of the first embodiment of the present invention.

Fig. 4 is a flowchart of an abnormal state detection method according to the first embodiment of the present invention.

Fig. 5 is a block diagram showing a configuration of a pulse width modulation signal generating apparatus according to a second embodiment of the present invention.

Fig. 6 is a circuit block diagram showing a partial circuit configuration in the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention.

Fig. 7 is a flowchart of an abnormal state detection method according to a specific example of the second embodiment of the present invention.

Fig. 8 is a waveform diagram of a first analog signal generated by a pwm signal generator according to a specific example of the second embodiment of the present invention when a pwm signal line short-circuits a battery power supply of an electronic device.

Fig. 9 is a waveform diagram of a first analog signal generated by the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention when the pulse width modulation signal line is short-circuited to ground.

Fig. 10 is a waveform diagram of an input signal to the pwm signal converter in the pwm signal generator according to a specific example of the second embodiment of the present invention when the pwm signal line is disconnected.

Fig. 11 is a waveform diagram of a first analog signal generated by the pwm signal generating apparatus according to a specific example of the second embodiment of the present invention when the pwm signal line is disconnected or normally connected.

Fig. 12 is a waveform diagram of an input signal to the pwm signal converter in the pwm signal generator according to a specific example of the second embodiment of the present invention when pwm signal lines are normally connected.

Fig. 13 is a waveform diagram of a second analog signal generated by the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention when the pulse width modulation signal line is disconnected.

Fig. 14 is a waveform diagram of a second analog signal generated by the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention when the pulse width modulation signal lines are normally connected.

Description of reference numerals:

1. 1A, 1B: pulse width modulation signal generating means; 10. 10A, 10B: a pulse width modulation signal generating section; 20: a pulse width modulation signal transmission unit; 30: a pulse width modulation signal extraction unit; 40: a pulse width modulation signal conversion section; 41: a first conversion circuit; 42: a second conversion circuit; 50: an abnormality detection unit; p1: an output terminal of the microprocessor; p11: a first input terminal; p12: a first output terminal; p21: a second input terminal; p22: a second output terminal; t1, T11: a switching transistor; r1, R20, R2, R3, R11, R12, R13, R14, R21, R22: a resistance; c1, C11, C12, C13, C21, C22, C23: a capacitor; d11, D21, D22: a diode; z21: a Zener diode; GND: grounding; 2: an electronic device; 201: a pulse width modulation circuit; 3: a pulse width modulation signal line; 4: a vehicle-mounted battery; 5: an electric motor.

Detailed Description

The present invention will be described in more detail below with reference to the accompanying drawings, embodiments, and specific examples. The following description is only an example for the convenience of understanding the present invention and is not intended to limit the scope of the present invention. In the embodiments, the components of the apparatus may be changed, deleted or added according to the actual situation, the components included in the circuit and the connection relationship thereof may be changed, deleted or added according to the actual situation, and the steps of the method may be changed, deleted, added or changed in order according to the actual situation.

(first embodiment)

The first embodiment of the present invention will be specifically explained. First, a pulse width modulation signal generation device 1 according to a first embodiment of the present invention will be described. Fig. 1 is a block diagram showing a configuration of a pulse width modulation signal generating apparatus according to a first embodiment of the present invention. As shown in fig. 1, in the present embodiment, the pulse width modulation signal generation device 1 generates a pulse width modulation signal (PWM signal) in accordance with, for example, an operation by a user, and transmits the generated PWM signal to an external electronic device 2 via a pulse width modulation signal line 3. The electronic device 2 is, for example, a motor control device, and controls the rotation speed of the motor based on the pulse width modulation signal output from the pulse width modulation signal generation device 1. Here, the electronic device 2 drives the motor not directly by the pulse width modulation signal generated by the pulse width modulation signal generation device 1, but by a pulse width modulation signal in which the phase and/or amplitude is changed with respect to the pulse width modulation signal.

However, various abnormal conditions such as a short circuit to ground and a short circuit to a power supply may occur on the pwm signal line 3 connecting the pwm signal generating apparatus 1 and the electronic apparatus 2. The pwm signal generation apparatus 1 extracts the modified pwm signal from the electronic apparatus 2 to detect an abnormal state of the pwm signal line 3. As shown in fig. 1, the pwm signal generation apparatus 1 includes a pwm signal generation unit 10, a pwm signal transmission unit 20, a pwm signal extraction unit 30, a pwm signal conversion unit 40, and an abnormality detection unit 50. The above-mentioned parts are implemented, for example, based on a hardware structure such as a circuit, at least a part of which may be implemented based on software by a processor executing a program in a memory, or may be implemented based on a dedicated circuit module by an integrated circuit executing a program in firmware. The following specifically describes each part of the pulse width modulation signal generation device 1.

The pulse width modulation signal generation unit 10 generates a first pulse width modulation signal (PWM signal) as a digital signal. The pwm signal generating section 10 includes, for example, a microprocessor, and generates a first pwm signal having an amplitude of, for example, 0 to 3.3V and a frequency of, for example, 35Hz, which is alternately at a high level and a low level, based on a voltage (for example, 5V) supplied from the pwm signal generating apparatus 1.

The pwm signal transmission unit 20 transmits the first pwm signal to the external electronic device 2 via the pwm signal line 3. The pwm signal transmission unit 20 is, for example, an output interface of the pwm signal generation apparatus 1, and is connectable to the pwm signal line 3.

The pulse width modulation signal extraction unit 30 extracts the second pulse width modulation signal from the electronic device 2. The second pulse width modulation signal is a pulse width modulation signal in which the amplitude and/or phase of the first pulse width modulation signal is changed. The pwm signal extraction unit 30 is, for example, an input interface of the pwm signal generation apparatus 1, and receives the second pwm signal, the phase and/or amplitude of which is changed by the electronic apparatus 2, from the electronic apparatus 2.

The pwm signal conversion unit 40 converts the second pwm signal extracted by the pwm signal extraction unit 30 from a digital signal to an analog signal. The pulse width modulation signal conversion unit 40 is a digital-to-analog conversion circuit including analog electronic devices such as a resistor, a capacitor, a diode, and a transistor, for example, and converts the second pulse width modulation signal from a digital signal to an analog signal reflecting the characteristics of the signal. For example, the pulse width modulation signal conversion section 40 may include a rectifier circuit for extracting a characteristic of a direct current component of the second pulse width modulation signal.

The abnormality detection unit 50 detects an abnormal state of the pwm signal line 3 based on a value obtained by converting the second pwm signal into an analog signal by the pwm signal conversion unit 40. The abnormality detection unit 50 is provided with, for example, a microprocessor, and detects an abnormal state of the pulse width modulation signal line 3 by comparing numerical values such as a voltage value and a current value of the analog signal input from the pulse width modulation signal conversion unit 40 with a preset abnormality determination threshold value by executing a program stored in advance.

Next, a pulse width modulation signal generation device 1A, which is a specific example of the first embodiment of the present invention, will be described. Fig. 2 is a circuit block diagram showing a partial circuit configuration in the pulse width modulation signal generation device 1A according to a specific example of the first embodiment of the present invention. Fig. 3 is a signal waveform diagram of a specific example of the first embodiment of the present invention.

In this specific example, the electronic device 2 is, for example, a vehicle-mounted motor control device, and can control the air output of the vehicle-mounted air conditioner by controlling the rotation speed of the motor 5 for the vehicle-mounted air conditioner. A control panel for controlling the air output of the vehicle air conditioner is also provided in the rear seat of the vehicle, and a pulse width modulation signal generation device 1A is provided for the control panel. When the passenger of the rear seat of the vehicle adjusts the control panel, the pwm signal generating device 1A generates a pwm signal having a duty ratio according to the operation of the passenger, and outputs the pwm signal to the electronic device 2 (motor control device) so that the pwm circuit 201 included in the electronic device 2 controls the rotation speed of the motor 5 for the in-vehicle air conditioner. Since the control panel is installed in the rear seat of the vehicle, the pwm signal generating apparatus 1A needs to be connected to the electronic apparatus 2 (motor control apparatus) via the pwm signal line 3, and there is a possibility that an abnormal state such as a short circuit to the ground or a short circuit to the power supply of the pwm signal line 3 occurs.

As shown in fig. 2, the pwm signal generation unit 10A of the pwm signal generation apparatus 1A outputs a pwm signal having a frequency of, for example, 35Hz, that is, the first pwm signal shown in the upper half of fig. 3, whose amplitude is 0 to 3.3V (typically, 3.3V), from the output terminal P1 of the microprocessor. The pulse width modulation signal generation unit 10A further includes a switching transistor T1, a resistor R1, and a capacitor C1. The output terminal P1 is connected to the base (control terminal) of the switching transistor T1, the collector of the switching transistor T1 is connected to the pwm signal transmitting unit 20 (here, the output terminal of the pwm signal generating apparatus 1A) via the resistor R1, and the emitter of the switching transistor T1 is grounded. The resistor R1 and the pwm signal transmitting unit 20 are connected to one end of the capacitor C1, and the other end of the capacitor C1 is grounded. As described above, the switching transistor T1 may be an NPN switching transistor, but may be a MOS transistor having a gate as a control terminal.

As described above, the first pwm signal is not directly used to drive the motor for the in-vehicle air conditioner, but is used to drive the motor for the in-vehicle air conditioner after the amplitude and/or phase thereof is changed by the electronic device 2. As shown in fig. 2, the electronic apparatus 2 is powered by an in-vehicle battery 4, and the battery voltage of the in-vehicle battery 4 is, for example, 9 to 18V (a typical value is, for example, 14V). The on-vehicle battery 4 is connected to the pulse width modulation signal line 3 via a resistor R20 of the electronic device 2.

When the pulse width modulation signal generation device 1A is normally connected to the electronic device 2 via the pulse width modulation signal line 3, and the first pulse width modulation signal output from the output terminal P1 of the microprocessor is at a high level (e.g., 3.3V), the switching transistor T1 is turned on, and the voltage supplied to the electronic device 2 is grounded via the resistor R20, the pulse width modulation signal line 3, the pulse width modulation signal transmission unit 20, and the resistor R1, so that the second pulse width modulation signal output from the electronic device 2 is at a low level (e.g., 0V). When the first pulse width modulation signal output from the output terminal P1 of the microprocessor is at a low level (e.g., 0V), the switching transistor T1 is turned off, and the second pulse width modulation signal output from the electronic device 2 becomes the battery voltage (typical value 14V) of the in-vehicle battery 4.

That is, when the pulse width modulation signal line 3 is normally connected, the second pulse width modulation signal becomes low level (0V) when the first pulse width modulation signal generated by the pulse width modulation signal generation unit 10A becomes high level; when the first pulse width modulation signal generated by the pulse width modulation signal generation unit 10A is at a low level, the second pulse width modulation signal is at a high level (battery power supply voltage of the in-vehicle battery 4). As shown in fig. 3, when the first pwm signal generated by the pwm signal generation unit 10A is switched between high and low levels, the second pwm signal of the electronic device 2 is switched between low and high levels, and the phases of the two signals are opposite to each other. In this specific example, the second pwm signal has an opposite phase, the same duty ratio, and a different amplitude (output voltage) than the first pwm signal.

Since the second pwm signal, the amplitude and/or the phase of which is changed by the electronic device 2, is different from the first pwm signal generated by the pwm signal generating unit 10A, if the pwm signal generating device 1A detects whether the potential of the first pwm signal is at a high level or a low level only after the first pwm signal is output, it is not possible to reliably distinguish between various abnormal states of the pwm signal line 3. In contrast, in this specific example, the second pwm signal is converted from a digital signal to an analog signal by the pwm signal conversion unit 40, and the abnormality detection unit 50 can detect a plurality of kinds of abnormal states of the pwm signal line 3 based on the value of the analog signal.

In this specific example, the electronic device 2 generates the second pwm signal by changing the amplitude and phase of the first pwm signal in conjunction with the partial circuit configuration included in the pwm signal generating unit 10A and the in-vehicle battery 4. That is, if the pwm signal generation apparatus 1A is not connected to the electronic apparatus 2 via the pwm signal line 3, the amplitude and/or phase of the first pwm signal is not changed, and the second pwm signal is not generated. Therefore, although the second pwm signal actually flows when the pwm signal line 3 is normally connected, it can be logically interpreted as: the pwm signal generating unit 10A generates a first pwm signal, and the pwm signal transmitting unit 20 transmits the first pwm signal to the external electronic device 2 via the pwm signal line 3, and the electronic device 2 changes the amplitude and phase of the first pwm signal to generate a second pwm signal.

In this specific example, the pwm signal transmission unit 20 (the output terminal of the pwm signal generation apparatus 1A) and the pwm signal extraction unit 30 (the input terminal of the pwm signal generation apparatus 1A) are implemented by one terminal. However, the pwm signal transmission unit 20 and the pwm signal extraction unit 30 may be implemented by different components or terminals.

The following describes an abnormal state detection method performed by the pulse width modulation signal generation devices 1 and 1A in the present embodiment and the above-described specific examples. Fig. 4 is a flowchart of an abnormal state detection method according to the first embodiment of the present invention. The flow of fig. 4 may be executed when the pwm signal generation apparatuses 1 and 1A are connected to the electronic apparatus 2 via the pwm signal line 3, for example, or may be executed periodically at a predetermined cycle after the connection, or may be executed based on a user instruction. The following step S101 is an example of a pulse width modulation signal extraction step, step S102 is an example of a pulse width modulation signal conversion step, and step S103 and step S104 are examples of an abnormality detection step.

In step S101, the pwm signal extraction unit 30 extracts the second pwm signal obtained by changing the amplitude and/or phase of the first pwm signal from the electronic device 2.

In step S102, the pulse width modulation signal conversion section 40 converts the second pulse width modulation signal from a digital signal to an analog signal. For example, the analog signal reflects the dc component (average value) of the second pwm signal.

In step S103, the abnormality detector 50 compares the value obtained by converting the second pwm signal into an analog signal with a predetermined abnormal state determination threshold. For example, the abnormality detection unit 50 compares the voltage value of the analog signal with a voltage threshold value for determining a short circuit to ground and a voltage threshold value for determining a short circuit to a power supply, which are set in advance.

In step S104, the abnormality detection unit 50 detects an abnormal state of the pwm signal line 3 based on the comparison result, and thereby detects an abnormal state of the pwm signal line 3 based on a value obtained by converting the second pwm signal into an analog signal. For example, when the voltage value of the analog signal is equal to or greater than a voltage threshold value set in advance for determining a short circuit with respect to the power supply, the abnormality detection unit 50 determines that the pulse width modulation signal line 3 is short-circuited with respect to the power supply; when the voltage value of the analog signal is less than or equal to a preset voltage threshold value for judging the short circuit to the ground, the pulse width modulation signal line 3 is judged to be short-circuited to the ground; when the voltage value of the analog signal is between the two threshold values, it is determined that the pwm signal line 3 is normally connected.

According to the pwm signal generation apparatuses 1 and 1A and the abnormal state detection method thereof of the present embodiment, it is possible to clearly detect the abnormal state of the pwm signal line 3 connecting the pwm signal generation apparatuses 1 and 1A and the electronic apparatus 2 with a simple circuit configuration without using a complicated digital logic circuit and determination logic.

(second embodiment)

The second embodiment of the present invention will be specifically explained. In the present embodiment, in addition to the first embodiment, a partial change is made in the pulse width modulation signal conversion and the abnormality detection. The following description focuses on differences of the present embodiment from the first embodiment, and the same or similar contents as or to the first embodiment will be omitted in the present embodiment.

Fig. 5 is a block diagram showing the configuration of a pulse width modulation signal generating apparatus 1B according to a second embodiment of the present invention. As shown in fig. 5, the pulse width modulation signal generation device 1B of the present embodiment includes a first conversion circuit 41 and a second conversion circuit 42.

The first conversion circuit 41 converts the second pulse width modulation signal from a digital signal to a first analog signal reflecting the duty ratio of the second pulse width modulation signal. For example, the first conversion circuit 41 includes a constant voltage power supply and a switching transistor, a control terminal of which is inputted with the second pulse width modulation signal or a signal obtained by processing the second pulse width modulation signal, and on/off of the switching transistor is controlled based on a high/low level of the second pulse width modulation signal, thereby generating a first analog signal reflecting a duty ratio of the second pulse width modulation signal. The circuit configuration of the first conversion circuit 41 is not limited to this as long as an analog signal reflecting the duty ratio of the second pulse width modulation signal can be generated.

The second conversion circuit 42 converts the second pulse width modulation signal from a digital signal to a second analog signal reflecting the peak voltage of the second pulse width modulation signal. For example, the second conversion circuit 42 includes a rectifier circuit, and rectifies the second pulse width modulation signal or a signal obtained by processing the second pulse width modulation signal, thereby generating a second analog signal reflecting the peak voltage of the second pulse width modulation signal. The configuration of the second conversion circuit 42 is not limited to this as long as it can generate an analog signal reflecting the peak voltage of the second pulse width modulation signal.

The abnormality detection unit 50 detects an abnormal state of the pulse width modulation signal line 3 based on the voltage value of the first analog signal and the voltage value of the second analog signal. For example, since the duty ratio of the second pulse width modulation signal is 0% or 100% when the pulse width modulation signal line 3 is short-circuited, various short-circuit abnormal states of the pulse width modulation signal line 3 can be detected based on the voltage value of the first analog signal. In addition, the abnormal state of the pulse width modulation signal line 3 may be detected based on the peak voltage of the second pulse width modulation signal by comparing the voltage value of the second analog signal with a preset voltage threshold. Further, the voltage value of the first analog signal and the voltage value of the second analog signal may be combined and determined to detect a plurality of kinds of abnormal states of the pulse width modulation signal line 3.

Thus, by generating a plurality of analog signals reflecting the duty ratio and the peak voltage of the second pulse width modulation signal extracted from the electronic device 2, it is possible to more reliably detect a plurality of kinds of abnormal states of the pulse width modulation signal line 3.

As a specific detection method, the abnormality detection unit 50 may detect whether the pulse width modulation signal line 3 is in a ground short-circuit abnormality state in which a ground is short-circuited or a power supply short-circuit abnormality state in which a battery power supply to the electronic device 2 is short-circuited, based on a voltage value of the first analog signal. Further, the abnormality detector 50 may detect whether the pulse width modulation signal line 3 is in an abnormal open circuit state in which the circuit is open or in a normal connection state based on the voltage value of the first analog signal and the voltage value of the second analog signal.

For example, when the pulse width modulation signal line 3 is short-circuited to the ground, the duty ratio of the second pulse width modulation signal is, for example, 0% (100% if the phase is inverted), and when the pulse width modulation signal line 3 is short-circuited to the battery power supply of the electronic device 2, the duty ratio of the second pulse width modulation signal is, for example, 100% (0% if the phase is inverted), the above-described two short-circuit states can be detected based on the voltage value of the first analog signal.

In addition, when the pwm signal line 3 is disconnected, it is assumed that the pwm signal extraction unit 30 cannot extract the second pwm signal from the electronic device 2 but can extract only the first pwm signal that is not transmitted to the electronic device 2. As described above, the first pulse width modulation signal and the second pulse width modulation signal have the same duty ratio (more than 0% and less than 100%), but have different peak voltages, and the open state can be detected based on the voltage values of both the first analog signal and the second analog signal.

Thus, by combining and determining the voltage values of the plurality of analog signals reflecting the duty ratio and the peak voltage of the second pulse width modulation signal extracted from the electronic device 2, it is possible to reliably detect a plurality of types of abnormal states such as a short-circuit state and a disconnection state of the pulse width modulation signal line 3.

Next, a partial circuit configuration of a specific example of the second embodiment of the present invention will be described. Fig. 6 is a circuit block diagram showing a partial circuit configuration of a specific example of the second embodiment of the present invention, and mainly shows circuit configurations of the pulse width modulation signal generation section 10B, the first conversion circuit 41, and the second conversion circuit 42. As shown in fig. 6, the circuit configuration of the pwm signal generator 10B is similar to that of the pwm signal generator 10A in one specific example of the first embodiment, and a first pwm signal having an amplitude of, for example, 3.3V is output from the output terminal P1 of the microprocessor. The pwm signal generator 10B further includes a switching transistor T1, resistors R1, R2, R3, and a capacitor C1, and the connection relationship between the switching transistor T1, the resistor R1, and the capacitor C1 is the same as that of the pwm signal generator 10A, and is not described again here. A resistor R2 is connected in parallel with the capacitor C1, and a resistor R3 is connected between the output terminal P1 of the microprocessor and the base of the switching transistor T1. The output terminal (pulse width modulation signal transmission unit 20) of the pulse width modulation signal generation unit 10B is connected to the electronic device 2 via the pulse width modulation signal line 3. In this specific example, the pwm signal transmission unit 20 and the pwm signal extraction unit 30 are implemented by one terminal.

In the first conversion circuit 41, the first input terminal P11 is connected to the pwm signal extraction unit 30, and the second pwm signal is input thereto. The constant voltage power supply outputs a constant voltage (5V in the figure) lower than the output voltage (for example, 14V) of the battery power supply of the electronic device 2. Further, a second-order RC filter circuit is formed by the resistors R12 and R13 and the capacitors C12 and C13, and low-pass filtering processing is performed as the first RC filter circuit. The switching transistor T11 is connected between the constant voltage power supply and the first RC filter circuit, and turns on or off the constant voltage power supply and the first RC filter circuit using the second pulse width modulation signal inputted from the first input terminal P11 as a control signal. The example in which the switching transistor T11 is a PNP switching transistor is shown in the figure, but is not limited thereto, and other types of switching transistors may be employed as appropriate. The first voltage dividing circuit is configured by the resistors R12 and R13 and the resistor R14, and divides the signal filtered by the first RC filter circuit, for example, the resistance value of the resistor R14 is 1.5 times the sum of the resistance values of the resistor R12 and the resistor R13, so that a divided signal having a voltage division ratio of 3/5 to the total voltage is output as the first analog signal from the first output terminal P12 connected between the resistor R13 and the resistor R14. The first conversion circuit 41 further includes a capacitor C11 connected between the constant voltage power supply and the Ground (GND), a diode D11 connected between the first input terminal P11 and the control terminal of the switching transistor T11 for isolating the reverse voltage, and a resistor R11 connected between the output terminal of the switching transistor T11 and the ground.

In the second converter circuit 42, the second input terminal P21 is connected to the pulse width modulation signal extraction unit 30 and the first input terminal P11 of the first converter circuit 41. Further, a rectifier circuit is formed by the capacitors C21 and C22 and the diodes D21 and D22, and rectifies a signal input from the second input terminal P21. A first-order RC filter circuit including the resistor R21 and the capacitor C23 is used as the second RC filter circuit, and low-pass filter processing is performed on the signal rectified by the rectifier circuit. A second voltage dividing circuit including the resistor R22 and the resistor R21 divides the signal filtered by the second RC filter circuit, for example, the resistance value of the resistor R22 is 1.2 times the resistance value of the resistor R21, so that a divided signal having a voltage dividing ratio of 6/11 with respect to the total voltage is output from the second output terminal P22 connected between the resistor R22 and the resistor R21 as a second analog signal. The second conversion circuit 42 further includes a zener diode Z21 connected between the second output terminal P22 and the ground as a protection circuit, but circuit elements may be deleted or added as appropriate according to the actual situation, and the circuit configuration of this specific example is not limited.

The following describes an abnormal state detection method performed by the pulse width modulation signal generation device 1B in the present embodiment and the above-described specific examples. Fig. 7 is a flowchart of an abnormal state detection method according to a specific example of the second embodiment of the present invention. The timing of execution of the flow shown in fig. 7 is the same as the flow shown in fig. 4 in the first embodiment, for example, step S201 described below exemplifies a pulse width modulation signal extraction step, step S202 exemplifies a pulse width modulation signal conversion step, and steps S203 to S209 exemplify an abnormality detection step.

In step S201, the pwm signal extraction unit 30 extracts the second pwm signal obtained by changing the amplitude and/or phase of the first pwm signal from the electronic device 2.

In step S202, the first conversion circuit 41 converts the second pulse width modulation signal from a digital signal to a first analog signal reflecting the duty ratio of the second pulse width modulation signal, and the second conversion circuit 42 converts the second pulse width modulation signal from a digital signal to a second analog signal reflecting the peak voltage of the second pulse width modulation signal.

Next, the abnormality detection unit 50 executes a power supply short detection step of detecting whether or not the pulse width modulation signal line 3 is in a power supply short abnormal state with respect to the battery power supply short of the electronic device 2, based on the voltage value of the first analog signal. Fig. 8 is a waveform diagram of a first analog signal according to a specific example of the second embodiment of the present invention when the pwm signal line 3 is short-circuited to the battery power supply of the electronic device 2. In the specific example of the partial circuit configuration shown in fig. 6, in the power supply short-circuit abnormal state, the voltage extracted by the pwm signal extraction unit 30 is the battery voltage (for example, 14V) of the electronic device 2. In this specific example, the switching transistor T11 of the first conversion circuit 41 turns on the constant voltage power supply and the first RC filter circuit only when a low level is input from the first input terminal P11, and therefore the switching transistor T11 remains off at this time, and the first analog signal output by the first conversion circuit 41 becomes a voltage close to 0V as shown in fig. 8.

In contrast, for example, in step S203, the abnormality detection unit 50 determines whether or not the voltage value of the first analog signal is equal to or less than a preset second threshold value, which is higher than 0V, for example, 0.1V slightly higher than 0V, and may be set as appropriate according to actual circumstances. When it is determined in step S203 that the voltage value of the first analog signal is equal to or less than the second threshold value, step S204 is executed, and the abnormality detection unit 50 detects that the pulse width modulation signal line 3 is in a power supply short-circuit abnormal state with respect to the battery power supply short-circuit of the electronic device 2.

When it is determined in step S203 that the voltage value of the first analog signal is higher than the second threshold (not in the power supply short-circuit abnormal state), the abnormality detection unit 50 executes a ground short-circuit detection step of detecting whether or not the pulse width modulation signal line 3 is in the ground short-circuit abnormal state in which the ground is short-circuited, based on the voltage value of the first analog signal. Fig. 9 is a waveform diagram of a first analog signal when the pwm signal line 3 is short-circuited to ground in a specific example of the second embodiment of the present invention. In the specific example of the partial circuit configuration shown in fig. 6, in the ground short-circuit abnormal state, the voltage extracted by the pwm signal extraction unit 30 is the ground voltage (0V). In this specific example, the switching transistor T11 of the first conversion circuit 41 turns on the constant voltage power supply and the first RC filter circuit only when a low level is input from the first input terminal P11, and therefore the switching transistor T11 remains on at this time, and the first analog signal output by the first conversion circuit 41 becomes a voltage (e.g., about 3V) obtained by dividing the voltage (e.g., 5V) of the constant voltage power supply as shown in fig. 9.

In contrast, for example, in step S205, the abnormality detection unit 50 determines whether or not the voltage value of the first analog signal is equal to or greater than a preset first threshold value, which is set to a voltage value lower than the voltage value of the output voltage of the constant voltage power supply of the first conversion circuit 41 divided by the first voltage dividing circuit and higher than the second threshold value, for example, set to 2.9V slightly lower than the divided voltage (3V), and may be set as appropriate depending on the actual situation. When it is determined in step S205 that the voltage value of the first analog signal is equal to or greater than the first threshold value, step S206 is executed, and the abnormality detection unit 50 detects that the pulse width modulation signal line 3 is in a short-to-ground abnormality state in which it is short-circuited to ground.

When it is determined in step S205 that the voltage value of the first analog signal is lower than the first threshold (and higher than the second threshold, that is, not in the ground short-circuit abnormal state or the power short-circuit abnormal state), the abnormality detector 50 executes a disconnection detecting step, which will be described in detail below.

Fig. 10 is a waveform diagram of an input signal to the pwm signal converter 40 when the pwm signal line 3 is disconnected in a specific example of the second embodiment of the present invention. In the specific example of the partial circuit configuration shown in fig. 6, in the disconnection abnormal state, the pwm signal extracting unit 30 cannot extract a signal from the electronic device 2 through the pwm signal line 3. When the first pwm signal outputted from the output terminal P1 of the microprocessor is at a high level, the switching transistor T1 is turned on and grounded, and the voltage extracted by the pwm signal extracting unit 30 is at a low level (close to 0V); when the first pwm signal is at a low level, the switching transistor T1 is turned off, and the voltage extracted by the pwm signal extraction unit 30 is at a high level (approximately 5V) by the constant voltage power supply of the first conversion circuit 41. Thus, the input signal to the pwm signal converter 40 when the pwm signal line 3 is disconnected becomes a signal shown in fig. 10.

Fig. 11 is a waveform diagram of a first analog signal when the pulse width modulation signal line 3 is disconnected according to a specific example of the second embodiment of the present invention. Since the first analog signal generated by the first conversion circuit 41 reflects the duty ratio of the input signal input to the pwm signal conversion section 40, the voltage value of the first analog signal varies depending on the duty ratio of the signal shown in fig. 10, and is between 0 and a voltage value (for example, 3V) obtained by dividing the output voltage value of the constant voltage power supply of the first conversion circuit 41 by the first voltage dividing circuit, as shown in fig. 11.

However, it is difficult for the abnormality detector 50 to reliably detect that the pulse width modulation signal line 3 is in the open-circuit abnormal state based only on the voltage value of the first analog signal. Specifically, it is difficult to distinguish the disconnection abnormal state from the normal connection state. Fig. 12 is a waveform diagram of an input signal to the pwm signal converter 40 in a specific example of the second embodiment of the present invention when the pwm signal lines 3 are normally connected. The waveform diagram is similar to the second pwm signal in the normal connection shown in fig. 3, and is not repeated here. Since the duty ratio of the input signal to be input to the pwm signal converter 40 is the same as that in the abnormal shutdown state, it is difficult to distinguish between the two states only by the voltage value of the first analog signal.

Therefore, the abnormality detector 50 also detects whether or not the pwm signal line 3 is in the open-circuit abnormal state of open circuit based on the voltage value of the second analog signal. Fig. 13 is a waveform diagram of a second analog signal generated by the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention when the pulse width modulation signal line is disconnected. Fig. 14 is a waveform diagram of a second analog signal generated by the pulse width modulation signal generation device according to a specific example of the second embodiment of the present invention when the pulse width modulation signal lines are normally connected. In the specific example of the partial circuit configuration shown in fig. 6, in the abnormal open state in which the pwm signal line 3 is open, the input signal to the pwm signal converter 40 becomes the signal shown in fig. 10, that is, the pulse signal having a high level of, for example, 5V, as described above. This signal is rectified, low-pass filtered, and voltage-divided by the second conversion circuit 42, and becomes, for example, a voltage value of about 0.5V as shown in fig. 13. In contrast, in the present specific example in which the partial circuit configuration is shown in fig. 6, in the normal connection state in which the pwm signal line 3 is normally connected, as described above, the input signal to the pwm signal converter 40 is the signal shown in fig. 12, that is, the pulse signal having a high level of, for example, 14V. This signal is rectified, low-pass filtered, and voltage-divided by the second conversion circuit 42, and becomes a voltage value of about 2V as shown in fig. 14, for example.

To continue the explanation with reference to fig. 7, for example, in step S207, the abnormality detection unit 50 determines whether or not the voltage value of the second analog signal is equal to or less than a preset third threshold value, which may be set to be lower than the voltage value of the second analog signal when the pulse width modulation signal line 3 is normally connected and higher than the voltage value of the second analog signal when the pulse width modulation signal line 3 is disconnected, for example, to 0.75V, and which may be set as appropriate according to the actual situation. When it is determined in step S207 that the voltage value of the second analog signal is equal to or less than the third threshold, step S208 is executed, and the abnormality detection unit 50 detects that the pulse width modulation signal line 3 is in the open-circuit abnormal state in which it is open-circuited.

On the contrary, when it is determined in step S207 that the voltage value of the second analog signal is higher than the third threshold, the normal connection determination step is executed. In step S209, the abnormality detection unit 50 detects that the pulse width modulation signal line 3 is in a normal connection state of normal connection.

According to the specific example and the abnormal state detection method described above, by combining the analog circuit configurations of the pwm signal generation unit 10B, the first conversion circuit 41, and the second conversion circuit 42, these circuits are interlocked with each other, so that the abnormal state of the short circuit to ground and the abnormal state of the short circuit to power supply of the pwm signal line 3 can be reliably detected, and the abnormal state of the open circuit and the normal connection state of the pwm signal line 3 can be distinguished.

The embodiments and specific examples of the present invention have been described above with reference to the accompanying drawings. The above-described embodiments and specific examples are merely specific examples of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art can modify the embodiments and specific examples based on the technical idea of the present invention, and various modifications, combinations, and appropriate omissions of the elements can be made, and the embodiments obtained thereby are also included in the scope of the present invention. For example, the above embodiments and specific examples may be combined with each other, and the combined embodiments are also included in the scope of the present invention.

However, in the above embodiments of the present invention, if the pwm signal line 3 is disconnected, short-circuited to the ground, or short-circuited to the battery power supply of the electronic device 2, the pwm signal extracting unit 30 of the pwm signal generating devices 1, 1A, and 1B may not be able to extract the second pwm signal from the electronic device 2. That is, the conversion target of the pulse width modulation signal conversion section 40 may not be the second pulse width modulation signal. However, it is not known whether or not the pwm signal line 3 is in an abnormal state before the pwm signal generation apparatuses 1, 1A, and 1B perform the abnormality detection process, that is, whether or not the signal extracted by the pwm signal extraction unit 30 is a signal other than the second pwm signal. Therefore, in the present application, the signals extracted by the pwm signal extraction unit 30 will be described as the second pwm signal in some cases. The signals extracted by the pwm signal extraction unit 30 in the respective abnormal states are specifically described in the above embodiments, and the essence of the signals will be clear to those skilled in the art after reading the above embodiments.

Further, the steps included in the abnormal state detection method according to each of the above embodiments of the present invention may be realized as steps included in an abnormal state detection program executed by a microprocessor or as a recording medium on which the abnormal state detection program is recorded, and the same technical effects can be obtained.