JP2000105612A - Power control unit for electric equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive an electric equipment with high accuracy by feedback- controlling the pulse occupancy rate of operation signal to operate a switching element with a simple circuit configuration and making the load current close to a target current. SOLUTION: The power control unit 21 is composed of a field-effect transistor(FET) 3 serially connected to a driving coil 2, a current detecting part 5, a microcomputer 22 for outputting a pulse width set driving signal VE, an integration circuit 27 and a pulse width increase/decrease circuit 28 or the like. The pulse width of the operation signal VG is increased/decreased by the current detecting circuit 5 and pulse width increase/decrease circuit 28. Even when a temperature around the driving coil 2 is changed, the pulse width increase/ decrease circuit 28 compares an integration signal VF with a detecting signal VC. Thus, the pulse width increased/decreased operation signal VG is outputted to the FET 3 and the load current iL is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric device for driving an electric device by supplying a signal to an electric device having an inductance component represented by, for example, an electric motor, an electromagnetic valve, an electromagnetic clutch, an electromagnetic relay and the like. Related to a power control device.

[0002]

2. Description of the Related Art Generally, electric motors, electric motors,
There are an electromagnetic valve, an electromagnetic clutch, an electromagnetic relay, and the like.For example, as an electromagnetic valve used for controlling an engine of an automobile, an idle control valve that controls a flow rate of air to correct an air-fuel ratio of the engine when idling, a combustion of the engine, When a part of the exhaust gas from the engine is introduced into the intake side of the engine in order to lower the temperature, there is an EGR control valve or the like that controls the flow rate of the gas. In addition, as such an electromagnetic valve, a valve that can freely set a valve opening in order to control the flow rate of each gas with high accuracy is used.

As a device for electronically controlling the solenoid valve, a power control device equipped with a microcomputer is known. Here, the power control device controls a flow rate of each gas by supplying a pulse signal to a drive coil (inductance component) of the electromagnetic valve to increase or decrease the valve opening of the electromagnetic valve. .

Further, the flow rate is adjusted by bringing the current value flowing through the drive coil closer to a target current value set in the microcomputer based on data from various sensors. In this case, the pulse width is adjusted. Modulation control (hereinafter referred to as PWM control) is used (for example, Japanese Patent Application Laid-Open No. Hei 9-14486).

Here, this type of power control device is shown in FIG.
A description will be given based on FIG. Here, a case where an idle control valve provided in an automobile is controlled will be described as an example.

Reference numeral 1 denotes a power control device according to the prior art. The power control device 1 includes a field effect transistor 3 as a switching element connected in series to a drive coil 2 of an idle control valve, the drive coil 2 and a battery power supply. 4 and a microcomputer 9 (hereinafter, referred to as a current detector 5) which detects a load current iL flowing through the drive coil 2 and outputs a DC command signal VA for driving the drive coil 2. An operation signal generator 15 for receiving a command signal VA output from the microcomputer 9 and generating a pulse-like operation signal VB; and receiving an operation signal VB output from the operation signal generator 15. And an element operation circuit 18 for operating the field effect transistor 3.

Here, the driving coil 2 as a load has an inductance L and a resistance value R, and the drain of the field effect transistor 3 is connected to the battery power supply 4 via the driving coil 2 and the current detecting resistor 6. , The source is connected to ground. Further, the battery power supply 4 has a DC voltage E
(For example, 12 V).

Reference numeral 5 denotes a current detection unit. The current detection unit 5 includes a current detection resistor 6 connected between the drive coil 2 and the battery power supply 4, and a current detection resistor 6 connected to both ends of the current detection resistor 6. It comprises a differential amplifier circuit 7 for outputting a current flowing through the current detecting resistor 6 as a detection signal VC, and a low-pass filter 8 connected to the output side of the differential amplifier circuit 7.
The current detector 5 detects the voltage across the current detection resistor 6 connected in series to the drive coil 2 to detect a detection signal VC corresponding to the load current iL flowing through the drive coil 2. The detection signal VC is output to the A / D converter 13 of the microcomputer 9 as a DC detection signal VD obtained by DC-converting the detection signal VC by the low-pass filter 8.

Reference numeral 9 denotes a microcomputer which constitutes a pulse width modulation means (PWM control means) together with an operation signal generating section 15 which will be described later. The microcomputer 9 is provided in a control unit of a vehicle (not shown).
1, a RAM 12, an A / D converter 13, a D / A converter 14, and the like.

A target current i0 to be supplied to the drive coil 2 is stored in the RAM 12 based on data read from a crank angle sensor (not shown), an idle switch, etc., and a DC detection signal VD read from the current detector 5. After the setting, a program (not shown) for setting a digital command signal VA corresponding to the target current i0 and the DC detection signal VD is stored.
Various predetermined values for performing arithmetic processing in U10 are stored. Further, the D / A converter 14 is
Is converted into a DC command signal VA.

Reference numeral 15 denotes an operation signal generator. The operation signal generator 15 includes a triangular wave generating circuit 1 for generating a basic triangular wave VT.
6 and the basic triangular wave V generated from the triangular wave generation circuit 16
It comprises a pulse width increasing / decreasing circuit 17 which sets and outputs a pulse-like operation signal VB by comparing T with a command signal VA output from the microcomputer 9.

As described above, the microcomputer 9 and the operation signal generator 15 perform pulse width modulation control (hereinafter referred to as PWM control) for increasing or decreasing the pulse width of the operation signal VB in order to drive the drive coil 2 with the target current i0. Is going.

Reference numeral 18 denotes an element operation circuit, and the element operation circuit 1
8 is an operation signal generator 15 and a field effect transistor 3
And a driver circuit for operating the field effect transistor 3.

Reference numeral 19 denotes a freewheel diode connected to both ends of the drive coil 2. The freewheel diode 19 is a counter-electromotive force stored in the drive coil 2 when the operation signal VB is switched from on to off. Is returned to the battery power supply 4 side to protect the field effect transistor 3.

Here, the operation of the power control device 1 according to the prior art will be described. First, the microcomputer 9 outputs data of a crank angle sensor, an idle switch, and the like, and a command signal VA set by a detection signal VC output from the current detection unit 5 to an operation signal generation unit 15. The 15 pulse width increasing / decreasing circuit 17 has a waveform as shown in the upper part of FIG.

That is, the triangular wave generating circuit 16 outputs a basic triangular wave VT at a preset frequency, and the pulse width increasing / decreasing circuit 17 compares the basic triangular wave VT with the command signal VA to output the triangular wave to the middle stage in FIG. As shown, pulse width modulation of the operation signal VB is performed, and the operation signal VB is output to the field effect transistor 3 through the element operation circuit 18.

In the field effect transistor 3,
The operation signal VB from the operation signal generator 15 is input, and the connection between the drain and the source is closed. At this time, since a current corresponding to the pulse width of the operation signal VB flows through the drive coil 2, the drive coil 2 generates an electromagnetic force by the supplied current and operates the idle control valve.

The impedance of the drive coil 2 changes due to a change in ambient temperature or the like.
May not coincide with the target current i0 set by the microcomputer 9. Therefore, in the power control device 1, the load current iL flowing through the drive coil 2 is detected by the current detection unit 5 as a detection signal VC, and the detection signal VC is read into the microcomputer 9, and the command signal VA output from the microcomputer 9 is used. The pulse width of the operation signal VB has been set by feedback control.

For example, when the ambient temperature of the drive coil 2 rises, the impedance component of the drive coil 2 increases, and the load current iL (the DC detection signal VD) is low as shown in the lower part of FIG. This becomes the signal VCL. At this time,
The actual load current iL flowing through the drive coil 2 is equal to the target current i
Since it is smaller than 0, the microcomputer 9 lowers the command signal VA according to the load current iL. This allows
The microcomputer 9 increases the pulse width of the operation signal VB and increases the load current iL flowing through the drive coil 2.

On the other hand, when the ambient temperature of the drive coil 2 drops, the detection signal VC output from the current detection unit 5
Becomes a high detection signal VCH. For this reason, the microcomputer 9 increases the command signal VA to reduce the pulse width of the operation signal VB so that the load current i flowing through the drive coil 2 is reduced.
Decrease L.

As described above, in the power control apparatus 1 according to the prior art, the load current iL flowing through the drive coil 2 is monitored by the current detecting section 5 so that the load current iL becomes the target current i0 set in the microcomputer 9. By performing feedback control on the idle control valve, the valve opening of the idle control valve is accurately adjusted.

[0022]

In the power control apparatus 1 according to the prior art, a triangular wave generating circuit 16 and a pulse width increasing / decreasing circuit 17 are used to generate a pulse-like operation signal VB separately from the microcomputer 9. There is a problem that the circuit configuration is complicated because the configured operation signal generating unit 15 is provided.

Further, since the A / D converter 13 and the D / A converter 14 are provided in the microcomputer 9, the microcomputer 9 itself becomes expensive. on the other hand,
Some recent microcomputers are inexpensive and have a PWM output unit that outputs a pulse-like waveform for PWM control. However, when this microcomputer is used in the power control device 1, the load current that has conventionally been performed in the microcomputer 9 is reduced. There is a problem in that feedback control for making iL close to the target current i0 cannot be performed.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention controls a pulse width of an operation signal by a simple circuit configuration so that a current flowing through an electric device approaches a target current. It is an object of the present invention to provide a power control device for electrical equipment that can be used.

[0025]

In order to solve the above-mentioned problems, a power control device for an electric device according to the present invention includes a switching element connected in series to a load of the electric device and operated by input of an operation signal; Current detection means for detecting a current flowing through the device as a detection signal, and output an operation signal to the switching element using a detection signal by the current detection means to drive the electric device at a target current,
And PWM control means for performing pulse width modulation control on the driving of the electric equipment.

The first aspect of the present invention is characterized in that the PWM control means includes a drive signal output means for outputting a drive signal having a pulse width set by a target current, and an output from the drive signal output means. Integrating means for integrating the obtained drive signal, and pulse width increasing / decreasing means for comparing the integrated signal output from the integrating means with the detection signal detected by the current detecting means to increase / decrease the pulse width.

With such a configuration, the integrating means converts the pulse-shaped drive signal output from the drive signal output means into a substantially triangular integrated signal by integrating. The pulse width increasing / decreasing unit compares the integration signal with the detection signal detected by the current detection unit. For example, an operation signal having a pulse width of a time interval when the integration signal is larger than the detection signal is converted into a switching element. Output to.

When the impedance component of the electric device changes due to a change in the ambient temperature,
The detection signal output from the current detection means fluctuates up and down in accordance with the change in the impedance component. At this time, the pulse width increasing / decreasing means increases / decreases the pulse width by comparing the detection signal with the integration signal, and outputs an operation signal pulse-width modulated based on the pulse width. For this reason, when the detection signal fluctuates up and down with respect to the integration signal, an operation signal whose pulse width is increased or decreased is output to the switching element, so that the driving of the electric device can be PWM-controlled.

According to the second aspect of the present invention, the pulse width increasing / decreasing means is configured such that a time interval when one of the integration signal and the detection signal is larger than the other signal is a pulse width. It is in.

With this configuration, when the current flowing through the electric device fluctuates, the detection signal fluctuates up and down with respect to the integration signal. Further, in the pulse width increasing / decreasing means, for example, when an operation signal whose pulse width is a time interval when the integration signal is larger than the detection signal is output, the pulse width of the operation signal is increased / decreased due to the fluctuation of the detection signal. Can be.

According to a third aspect of the present invention, the integration means is configured such that the integration signal has a substantially triangular waveform whose rising and falling characteristics extend substantially linearly with the vertex interposed therebetween.

With such a configuration, the pulse width increasing / decreasing means uses a substantially triangular integrated signal whose rising and falling characteristics extend substantially linearly across the apex and a change in the impedance component of the electric device. The pulse width of the operation signal can be increased or decreased between the rising side and the falling side by comparing the detection signal which fluctuates up and down.

According to a fourth aspect of the present invention, the drive signal output means is constituted by a microcomputer having a pulse width modulation output section for modulating the pulse width of the drive signal.

With such a configuration, a target current to be passed through the electric equipment is set in the microcomputer based on, for example, data read from various sensors.
A drive signal having a pulse width corresponding to the target current is output to an integrating means by a built-in pulse width modulation output unit.

According to a fifth aspect of the present invention, the current detecting means has a DC conversion circuit for converting a detection signal into DC.

With such a configuration, when the impedance component of the electric device changes, the pulse width increasing / decreasing means compares the substantially triangular integrated signal with the DC-converted detection signal that fluctuates up and down, and The operation signal having the increased or decreased width can be output to the switching element.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a power control device according to the present invention will be described below in detail with reference to FIGS. In the present embodiment, the same components as those of the above-described related art are denoted by the same reference numerals, and description thereof will be omitted.

First, a first embodiment will be described with reference to FIGS. 1 and 2 with an example of controlling an idle control valve.

Reference numeral 21 denotes a power control device according to the present embodiment. The power control device 21 is, similarly to the power control device 1 according to the prior art, a field-effect transistor 3 serving as a switching element, a current detection unit 5, A microcomputer 22 (hereinafter, referred to as a microcomputer 22), an integrating circuit 27, a pulse width increasing / decreasing circuit 28, an element operating circuit 18, and the like.

Reference numeral 22 denotes a microcomputer as drive signal output means. The microcomputer 22 includes a CPU 23, a ROM 24,
M25, a pulse width modulation output unit 26 (hereinafter, referred to as a PWM output unit 26) and the like. Also, the RAM 25
The microcomputer 22 stores a program (not shown) for setting a target current i0 to be supplied to the drive coil 2 based on data read from a crank angle sensor, an idle switch, and the like (not shown). .

Further, the PWM output section 26 outputs the target current i
The drive signal VE is set to a pulse-like drive signal VE corresponding to 0 (see the upper part of FIG. 2), and the drive signal VE is output to the integration circuit 27. When the target current i0 changes according to data from various sensors, the pulse width (duty ratio) of the drive signal VE changes.

Reference numeral 27 denotes an integration circuit. The integration circuit 27 receives the pulse-shaped drive signal VE input from the microcomputer 22,
A substantially triangular integrated signal VF whose rising and falling characteristics extend substantially linearly across the vertex (see the middle part in FIG. 2).
It has a time constant that changes to

Here, as shown in FIG. 2, although the integration signal VF has an output substantially synchronized with the drive signal VE, the detection signal VC output from the current detector 5 has a phase difference φ in the time axis direction. ing. The phase difference φ is set by the resistance value R and the inductance L of the drive coil 2. The integration signal VF is a substantially triangular signal substantially similar to the detection signal VC.

Reference numeral 28 denotes a pulse width increasing / decreasing circuit which constitutes a pulse width modulation control means (PWM control means) together with the microcomputer 22 and the integrating circuit 27. The pulse width increasing / decreasing circuit 28 includes an integrated signal VF output from the integrating circuit 27 and The detection signal VC output from the current detection section 5 is compared with the detection signal VC, and an operation signal VG having a pulse width of a time interval when the integration signal VF is larger than the detection signal VC is output to the element operation circuit 18. .

Also, unlike the current detection unit 5 according to the prior art, the low-pass filter 8 is not connected to the current detection unit 5 according to the present embodiment. The detection signal VC as shown is output to the pulse width increasing / decreasing circuit 28 as a substantially triangular waveform.

Here, the operation of the power control device 21 configured as described above will be described.

First, the microcomputer 22 sets a target current i0 to be supplied to the drive coil 2 based on data read from a crank angle sensor, an idle switch, and the like. Further, the PWM output unit 26 sets the target current i0. , And outputs this signal VE to the integration circuit 27 (see the upper part of FIG. 2).

Next, the integration circuit 27 converts the pulse-shaped drive signal VE into a substantially triangular integration signal VF, and outputs the integrated signal VF to the pulse width increasing / decreasing circuit 28.

On the other hand, the current detecting section 5 detects the detection signal VC corresponding to the load current iL flowing through the driving coil 2 by the current detecting resistor 6 and the differential amplifier circuit 7 as described in the prior art. The signal VC is applied to a pulse width increasing / decreasing circuit 28.
Output to

Further, in the pulse width increasing / decreasing circuit 28, the integrated signal VF inputted from the integrating circuit 27 and the current detecting section 5
And the integrated signal VF.
Is output to the gate of the field-effect transistor 3 through the element operation circuit 18 (see the middle and lower rows in FIG. 2). ).

As a result, the operation signal VG output from the pulse width increasing / decreasing circuit 28 is input to the gate of the field effect transistor 3, and the connection between the drain and the source is closed. At this time, since a current corresponding to the pulse width of the operation signal VG flows through the drive coil 2, the drive coil 2 generates an electromagnetic force by the supplied current and adjusts the opening of the idle control valve.

On the other hand, when the impedance component of the drive coil 2 changes due to a change in ambient temperature or the like, the actual load current iL flowing through the drive coil 2 is reduced by the microcomputer 22.
May not coincide with the target current i0 set in the above. Therefore, in the power control device 21, the load current iL flowing through the drive coil 2 is monitored as a detection signal VC by the current detection unit 5, and the pulse width increasing / decreasing circuit 28 compares the detection signal VC with the integration signal VF. Feedback control for setting the pulse width of the operation signal VG is performed.

That is, when the ambient temperature of the drive coil 2 rises, the impedance component of the drive coil 2 also increases, and the load current iL (detection signal VC) decreases as shown in the middle part of FIG. VCL, and the actual load current iL flowing through the drive coil 2 becomes smaller than the target current i0. At this time, the pulse width increasing / decreasing circuit 28 sets the time interval as the pulse width when the integration signal VF becomes larger than the detection signal VCL.
Outputs an operation signal VG whose pulse width is increased on the rising side and the falling side to the element operation circuit 18. As a result, the load current iL flowing through the drive coil 2 increases.

On the other hand, when the ambient temperature of the drive coil 2 decreases, the impedance component of the drive coil 2 decreases, and the load current iL (detection signal VC) increases as shown in the middle part of FIG. VCH, and the actual load current iL flowing through the drive coil 2 becomes larger than the target current i0. At this time, the pulse width increasing / decreasing circuit 28 sets the time interval when the integrated signal VF becomes larger than the detection signal VCH as the pulse width.
Outputs an operation signal VG having a reduced pulse width on the rising side and the falling side to the element operation circuit 18. As a result, the load current iL flowing through the drive coil 2 decreases.

As described above, the power control device 21 feedback-controls the pulse width of the operation signal VG for operating the field-effect transistor 3, so that the operation signal V
The time during which the field-effect transistor 3 is closed can be adjusted by G to make the load current iL flowing through the drive coil 2 close to the target current i0.

Further, the integration signal VF output from the integration circuit 27 has a substantially triangular waveform whose rising and falling characteristics extend substantially linearly with the vertex in between. As a result, the pulse width of the operation signal VG corresponding to the fluctuation of the detection signal VC can be changed more accurately than in the case where the rising characteristic becomes convexly curved and the falling characteristic becomes concavely curved.

Thus, in the power control device 21 according to the present embodiment, the current flowing through the drive coil 2 is detected by the detection signal VC.
, A microcomputer 22 that outputs a drive signal VE having a pulse width set to drive the drive coil 2 with the target current i0, and an integration that integrates the drive signal VE output from the microcomputer 22. The circuit 27 compares the integration signal VF output from the integration circuit 27 with the detection signal VC output from the current detection unit 5, so that the operation signal VG having the pulse width set is transmitted to the field effect transistor 3. And a pulse width increasing / decreasing circuit 28 that outputs the pulse width to the output.

Thus, in the pulse width increasing / decreasing circuit 28,
Comparing the integration signal VF with the detection signal VC, the operation signal VG
Is controlled by feedback, the load current iL flowing through the drive coil 2 is made closer to the target current i0 by performing this feedback control even when the load current iL does not match the target current i0. The valve opening of the idle control valve can be adjusted accurately.

Since the power control device 21 uses the microcomputer 22 having the PWM output section 26 for generating the pulse-like drive signal VE, it has an A / D converter, a D / A converter and the like. A relatively inexpensive microcomputer can be used as compared with a microcomputer.

Further, unlike the prior art, the pulse width increasing / decreasing circuit 17 for generating the pulse-like operation signal VB is not required, and the load current iL fluctuates due to a change in the ambient temperature or the like with a simple circuit configuration. And the target current i
The power control device 21 that can approach 0 can be configured.

As a result, by making the load current iL flowing through the drive coil 2 close to the target current i0, the opening degree of the idle control valve used as an electric device can be accurately adjusted.

Next, a second embodiment will be described with reference to FIGS. 3 and 4. In this embodiment, a low-pass filter 8 is provided at a stage subsequent to the differential amplifier circuit 7 in the current detector 5. That is. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 31 denotes a power control device according to the present embodiment. The power control device 31 is substantially the same as the power control device 21 according to the first embodiment, and includes a field-effect transistor 3, a current detection unit 5, and a microcomputer. 22, an integrating circuit 27, a pulse width increasing / decreasing circuit 28, an element operating circuit 18, and the like.

The current detection unit 5 used in this embodiment
Since the low-pass filter 8 is provided at the subsequent stage of the differential amplifier circuit 7, the detection signal VC output from the differential amplifier circuit 7 is converted by the low-pass filter 8 into a DC detection signal VD that does not substantially vary with time. The DC detection signal VD is output to the pulse width increasing / decreasing circuit 28.

Further, in the pulse width increasing / decreasing circuit 28, FIG.
As shown in FIG.
F is compared with the DC detection signal VD output from the current detection unit 5, and an operation signal VH having a pulse width of a time interval when the integrated signal VF is larger than the DC detection signal VD is output to the element operation circuit 18. Is what you do.

The power control device 31 having the above-described configuration also employs the power control device 21 according to the above-described first embodiment.
It is possible to operate almost the same as.

That is, when the ambient temperature of the drive coil 2 rises, the impedance component of the drive coil 2 increases, and the load current iL (the DC detection signal VD) decreases as shown in the middle part of FIG. It becomes the detection signal VDL, and the actual load current iL flowing through the drive coil 2 becomes smaller than the target current i0. At this time, in the pulse width increasing / decreasing circuit 28,
The operation signal VH is set by comparing the integration signal VF with the DC detection signal VDL.
An operation signal VH having a pulse width increased on the rising side and the falling side can be output to the element operation circuit 18.

On the other hand, when the ambient temperature of the drive coil 2 decreases, the impedance component of the drive coil 2 decreases, and the load current iL (the DC detection signal VD) increases as shown in the middle part of FIG. The detection signal VDH is output, and the actual load current iL flowing through the drive coil 2 becomes larger than the target current i0. At this time, in the pulse width increasing / decreasing circuit 28,
Since the operation signal VH is set by comparing the integration signal VF with the DC detection signal VDH, the pulse width increasing / decreasing circuit 28 outputs
An operation signal VH having a reduced pulse width on the rising side and the falling side can be output to the element operation circuit 18.

Thus, in the power control device 31, as in the case of the above-described power control device 21, the load current iL flowing through the drive coil 2 can be brought close to the target current i0 with a simple circuit configuration. In addition, when an idle control valve or the like is used as the electric device, the valve opening can be accurately adjusted.

In each of the embodiments, a field effect transistor is used as a switching element. However, the present invention is not limited to this, and a switching transistor, a triac, or the like may be used.

The current detecting means according to the present invention is exemplified by the case where the current detecting means is constituted by the current detecting resistor 6, but the present invention is not limited to this. For example, a current sensor using a Hall element as the current detecting means may be used. You may comprise by a semiconductor sensor.

Further, in each of the embodiments, the idle control valve is controlled as the electric device by the power control device. However, the present invention is not limited to this.
Of course, it may be used for an electromagnetic clutch, an electromagnetic relay or the like.

[0073]

As described above in detail, according to the first aspect of the present invention, a drive signal whose pulse width is set by the target current is output from the drive signal output means, and the drive signal is integrated by the integration means. The pulse width increasing / decreasing unit compares the integration signal by the integration unit with the detection signal detected by the current detection unit, and for example, switches an operation signal having a pulse width to a time interval when the integration signal is larger than the detection signal. It is configured to output to. Thus, when the impedance component of the electric device changes due to a change in the ambient temperature, the pulse width increasing / decreasing unit outputs an operation signal having a pulse width obtained by comparing the detection signal and the integration signal to the switching element. Then, the switching element is operated. As a result, the current flowing through the electric device can be made closer to the target current, and the electric device can be adjusted with high accuracy with a simple circuit configuration.

According to the second aspect of the present invention, the pulse width increasing / decreasing means is configured such that a time interval when one of the integration signal and the detection signal is larger than the other signal is a pulse width. If the pulse width increasing / decreasing means outputs, for example, an operation signal whose pulse width is the time interval when the integration signal is larger than the detection signal, the pulse width increasing / decreasing means fluctuates up and down with respect to the integration signal The pulse width of the operation signal can be increased or decreased by the detection signal.

According to the third aspect of the present invention, the integrating means is configured such that the integral signal has a substantially triangular waveform whose rising and falling characteristics extend substantially linearly with a straight line interposed therebetween.
In the pulse width increasing / decreasing means, even when the impedance component of the electric device changes, the pulse width is increased / decreased on the rising side and the falling side by comparing the substantially triangular integrated signal with the detection signal fluctuating up and down. The operation signal can be output to the switching element.

According to the fourth aspect of the present invention, the drive signal output means is constituted by a microcomputer having a pulse width modulation output section for modulating the pulse width of the drive signal.
The microcomputer sets a target current to flow to the electric device based on data read from various sensors, and a built-in pulse width modulation output unit outputs a pulse width corresponding to the target current to the integrating means as a drive signal. Output.

According to the fifth aspect of the present invention, since the current detecting means has a DC conversion circuit for converting the detection signal into a DC signal, the pulse width increasing / decreasing means is capable of generating a substantially triangular-shaped signal when the impedance component of the electric device changes. By converting the detection signal that fluctuates up and down with respect to the integration signal of the above into a direct current and comparing it, it is possible to output an operation signal whose pulse width is increased or decreased to the switching element.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a power control device according to a first embodiment.

FIG. 2 is a characteristic diagram showing a drive signal, an integration signal, and an operation signal in the power control device according to the first embodiment.

FIG. 3 is a circuit diagram showing a power control device according to a second embodiment.

FIG. 4 is a characteristic diagram showing a drive signal, an integration signal, and an operation signal in a power control device according to a second embodiment.

FIG. 5 is a circuit diagram showing a power control device according to the related art.

FIG. 6 shows a basic triangular wave in a power control device according to the prior art;
FIG. 4 is a characteristic diagram illustrating an operation signal and a detection signal.

[Explanation of symbols]

 Reference Signs List 2 drive coil (electric device) 3 field effect transistor (switching element) 4 battery power supply 5 current detection section (current detection means) 6 current detection resistor 7 differential amplifier circuit 8 low-pass filter (DC conversion circuit) 18 element operation circuit 21, 31 power control device 22 microcomputer 26 PWM output section (pulse width modulation output section) 27 integration circuit (integration means) 28 pulse width increase / decrease circuit (pulse width increase / decrease means) VC detection signal VD DC detection signal VE drive signal VF integration Signal VG, VH operation signal

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroshi Sato 1370 Onna, Atsugi-shi, Kanagawa F-term in Unisia Gex Co., Ltd. (reference) 3H106 FA04 KK17 5H410 BB05 CC02 DD02 DD06 EA11 EB25 EB27 FF05 FF24 5H430 BB01 BB09 BB12 EE06 EE17 FF08 FF12 GG11 HH03

Claims (5)

[Claims] 1. A switching element connected in series to a load of an electric device and operated by input of an operation signal, current detection means for detecting a current flowing through the electric device as a detection signal, and driving the electric device at a target current. Therefore, a power control device for electric equipment, comprising: a PWM control means for outputting an operation signal to the switching element using a detection signal from the current detection means and performing pulse width modulation control on driving of the electric equipment, wherein the PWM control means A drive signal output means for outputting a drive signal having a pulse width set by a target current; an integration means for integrating the drive signal output from the drive signal output means; an integration signal output from the integration means; And a pulse width increasing / decreasing means for increasing / decreasing a pulse width by comparing with a detection signal detected by the current detecting means. Equipment of the power control unit. 2. The pulse width increasing / decreasing means is configured such that a time interval when one of the integration signal and the detection signal is larger than the other signal is a pulse width. Power control device for electrical equipment. 3. The integration means according to claim 1, wherein the integration signal is configured such that a rising characteristic and a falling characteristic have a substantially triangular waveform extending substantially linearly with the vertex interposed therebetween. Power control device for electrical equipment. 4. The power control device for an electric device according to claim 1, wherein said drive signal output means comprises a microcomputer having a pulse width modulation output section for modulating a pulse width of the drive signal. . 5. The power control device for an electric device according to claim 1, wherein said current detection means includes a DC conversion circuit for converting a detection signal into DC.