JP6295810B2 - Load drive control device - Google Patents

Description

  The present invention relates to a load drive control device that controls driving of an inductive load.

  Conventionally, as disclosed in Patent Document 1, for example, a transistor that is provided on a current path of a linear solenoid as an inductive load, interrupts the current path, and a PWM (Pulse as a duty signal that turns this transistor on and off An inductive load energization control device having a linear solenoid control IC that outputs a (Width Modulation) signal has been proposed.

  In this energization control device, the linear solenoid control IC changes the PWM cycle according to the target current value to be passed through the linear solenoid. Specifically, when the target current value decreases, that is, when the duty ratio of the PWM signal decreases, the PWM cycle is lengthened. Thus, even when the duty ratio is small, the amplitude of the current of the linear solenoid can be prevented from becoming too small. As a result, it is possible to suppress the amplitude of the member stroked by the linear solenoid from becoming too small, and to prevent the generation of frictional resistance.

JP 2002-262549 A

  In the energization control device described above, the duty ratio of the PWM signal is determined based on the deviation between the target current value and the actual current value of the linear solenoid so that a current corresponding to the target current value is energized to the linear solenoid.

  More specifically, the potentials at both ends of the current detection resistor connected in series to the linear solenoid are taken into the linear solenoid control IC at regular time intervals. The linear solenoid control IC calculates the actual current value of the linear solenoid based on the difference between the potentials at both ends. Further, the linear solenoid control IC calculates a deviation between the target current value and the actual current value and integrates the deviation. The integrated deviation is added to the target current value, and the duty ratio of the PWM signal is determined based on the added value.

  However, the both-end potential of the current detection resistor is merely taken into the linear solenoid control IC at regular intervals regardless of the length of the PWM cycle. For this reason, when the length of the PWM cycle is changed, the number of times of calculation of the actual current value per cycle varies. As a result, the accuracy of PWM control may be reduced due to fluctuations in the actual current value calculation count.

  The present invention has been made in view of the above-described points, and is a load drive control device capable of keeping the number of detections of actual current per cycle constant even when the cycle of the duty signal changes. The purpose is to provide.

In order to achieve the above object, a load drive control device for controlling driving of an inductive load (100) according to claim 1,
Switching means (12) provided on the inductive load energization path and energizing the inductive load with a current corresponding to the duty ratio of the duty signal by turning on and off according to a given duty signal;
An actual current value detecting means (16) for detecting an actual current value of the inductive load;
Duty ratio that sets the duty ratio of the duty signal so that the actual current value follows the target current value based on the deviation between the target current value of the inductive load and the actual current value detected by the actual current value detection means Setting means (S130);
Period setting means (S100) for setting the length of the period of the duty signal;
A duty signal generating means (26) for generating a duty signal according to the length of the period set by the period setting means and the duty ratio set by the duty ratio setting means, and giving the duty signal to the switching means,
The actual current value detecting means detects the actual current value a plurality of times during one cycle of the duty signal, and the duty ratio setting means corresponds to the average current from the actual current value detected a plurality of times. The actual current value is calculated, and the duty ratio is set using the actual current value corresponding to the average current,
Further, in synchronization with the setting of the cycle length of the duty signal by the cycle setting means, even if the cycle of the duty signal is varied by the cycle setting means, the number of detection times of the actual current per cycle of the duty signal is set. In order to keep constant, the actual current value detecting means includes an interval setting means (S110) for setting an interval for detecting the actual current.

  As described above, the load drive control device according to the present invention includes the interval setting means for setting the interval for detecting the actual current. The interval setting unit sets the detection interval of the actual current so that the number of detections of the actual current per cycle of the duty signal is kept constant even if the cycle of the duty signal is varied by the cycle setting unit. Therefore, the actual current value detecting means detects the actual current according to the interval set by the interval setting means, so that even if the period of the duty signal is varied by the period setting means, the actual current per cycle of the duty signal is changed. It is possible to keep the number of times of detection of a constant. As a result, it becomes possible to set the duty ratio based on the actual current value with high accuracy.

  The reference numerals in the parentheses merely show an example of a correspondence relationship with a specific configuration in an embodiment described later in order to facilitate understanding of the present invention, and are intended to limit the scope of the present invention. Not intended.

  Further, the technical features described in the claims of the claims other than the features described above will become apparent from the description of embodiments and the accompanying drawings described later.

It is the block diagram which showed schematic structure of the load drive control apparatus by embodiment. It is the flowchart which showed the synchronous process for synchronizing a PWM period and an A / D conversion interval while determining a PWM period and a duty ratio. It is the flowchart which showed the subroutine for calculating a PWM period. It is the flowchart which showed the subroutine for calculating the duty ratio of a PWM signal. It is a timing chart for demonstrating the action | operation by the process shown to the flowchart of FIGS. It is the timing chart which showed a mode that the specific calculation method of an A / D conversion interval was demonstrated, and a PWM period and an A / D conversion interval were synchronized. 9 is a flowchart illustrating a process for setting an execution time of a synchronization process in the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, common or related elements are given the same reference numerals.

(First embodiment)
First, an inductive load whose drive is controlled by the load drive control device 10 according to the present embodiment will be described. For example, a linear solenoid 100 of a spool valve type hydraulic control valve can be employed as the inductive load. In this spool valve type hydraulic control valve, a spool as a valve body is slidably accommodated in a sleeve as a valve housing. The sleeve includes an input port to which hydraulic oil is supplied, an output port to which hydraulic oil is delivered, and a feedback port into which a part of the hydraulic oil that has flowed out of the output port is introduced. The hydraulic oil supplied from the input port into the spool valve type hydraulic control valve is sent out from the output port through a gap between the sleeve and the spool. The spool is stroked by the electromagnetic force generated by the linear solenoid 100, and the relative position (stroke position) to the sleeve is controlled. Thus, the flow rate and pressure of the hydraulic oil delivered from the output port are controlled by changing the overlapping length of the sleeve and the spool, that is, the gap length between the sleeve and the spool.

  The hydraulic pressure controlled by the hydraulic control valve is used, for example, to control the automatic transmission of the vehicle to the target gear stage. Alternatively, it is used in a so-called hydraulic variable valve timing mechanism to change the valve opening / closing timing of the intake or exhaust valve.

  The linear solenoid 100 has a coil and a plunger, and the stroke position of the plunger, and thus the spool connected to the plunger, is controlled by controlling the energization current to the coil.

  Next, a schematic configuration of the load drive control device 10 will be described with reference to FIG. As shown in FIG. 1, the load drive control device 10 includes a switching element 12, a microcomputer 14, and a current detection unit 16.

  The switching element 12 is provided on the energization path of the linear solenoid 100 and is turned on and off by a PWM signal as a duty signal supplied from the microcomputer 14. When the switching element 12 is turned on, a current is supplied to the linear solenoid 100, and when the switching element 12 is turned off, the current supply is interrupted. A current having an arbitrary magnitude can be supplied to the linear solenoid 100 in accordance with the ON / OFF ratio (duty ratio) of the PWM signal. In the present embodiment, a MOSFET is employed as the switching element 12. However, switching elements other than MOSFETs may be used. The switching element 12 is provided on the downstream side of the linear solenoid 100, but may be provided on the upstream side. The switching element 12 corresponds to the switching means described in the claims.

  The microcomputer 14 has a general configuration including a CPU, a ROM, a RAM, a register, and the like. In the microcomputer 14, the CPU controls the driving of the switching element 12 by executing various arithmetic processes according to a program stored in the ROM, based on an input signal or the like, temporarily using the RAM and the register as a storage area. The PWM signal for generating is generated. Thereby, the energization current of the linear solenoid 100 is controlled so as to follow the target current. Details of various arithmetic processes executed in the microcomputer 14 will be described later.

  The current detection unit 16 includes a current detection resistor 18 connected in series to the linear solenoid 100, and an operational amplifier 20 that amplifies the potential difference between both ends of the resistor 18 and outputs the amplified potential difference to the microcomputer 14. The current detection unit 16 corresponds to the actual current value detection means described in the claims.

  The resistor 18 has one end connected to the upstream terminal of the linear solenoid 100 and the other end connected to a power source. For this reason, when a current flows through the linear solenoid 100, a current equivalent to the current flowing through the linear solenoid 100 flows through the resistor 18. The operational amplifier 20 has a positive input terminal electrically connected to the upstream terminal of the resistor 18 and a negative input terminal electrically connected to the downstream terminal. The output terminal of the operational amplifier 20 is connected to the microcomputer 14.

  With this configuration, when a current equivalent to that of the linear solenoid 100 flows through the resistor 18, a potential difference corresponding to the magnitude of the current is generated at both ends of the resistor 18. The operational amplifier 20 amplifies the potential difference between both ends of the resistor 18 and outputs the amplified difference to the microcomputer 14. Therefore, the microcomputer 14 can detect the current (actual current value) flowing through the linear solenoid 100.

  Next, a functional schematic configuration of the microcomputer 14 will be described. As shown in FIG. 1, the microcomputer 14 includes an A / D conversion unit 22, a calculation unit 24, and a PWM signal output unit 26. The A / D conversion unit 22 samples the potential difference between both ends of the resistor 18 output from the operational amplifier 20 for each A / D interval determined by the calculation unit 24, and performs A / D conversion. From this A / D conversion result, the microcomputer 14 can calculate the actual current value of the linear solenoid 100. That is, the microcomputer 14 detects the actual current value of the linear solenoid 100 at every predetermined A / D interval using the A / D conversion unit 22.

  The calculation unit 24 calculates a target current value corresponding to the target hydraulic pressure so that the hydraulic control valve can generate the target hydraulic pressure. The target hydraulic pressure may be given from an external control device, or may be calculated by the microcomputer 14 based on various sensor signals. The relationship between the target hydraulic pressure and the target current value is determined in advance, and is stored in the ROM of the microcomputer 14 as a map, for example. Then, the calculation unit 24 determines the duty ratio of the PWM signal based on the calculated target current value and the actual current value calculated from the A / D conversion result in the A / D conversion unit 22. In calculating the duty ratio, for example, PID calculation is used.

  Further, the calculation unit 24 receives a detection signal from a temperature sensor (not shown) that detects the temperature of the hydraulic oil whose pressure is controlled by the hydraulic control valve, and calculates the temperature of the hydraulic oil based on the detection signal. . Then, the cycle of the PWM signal (hereinafter, PWM cycle) is determined from the calculated temperature of the hydraulic oil.

  The PWM signal output unit 26 generates a PWM signal according to the duty ratio and the PWM cycle determined by the calculation unit 24 and outputs the PWM signal to the switching element 12. The PWM signal output unit 26 corresponds to duty signal generation means described in the claims. Although not shown, the PWM signal output unit 26 includes a register for storing data for defining the PWM signal to be output, and the duty ratio and cycle determined by the calculation unit 24 are as follows. Stored in a register. Then, when the next PWM cycle is started, the PWM signal output unit 26 generates a PWM signal according to the cycle and duty ratio stored in the register, and outputs the PWM signal to the switching element 12.

  Next, detailed control processing in the microcomputer 14 will be described with reference to the flowcharts of FIGS. 2 to 4 and the timing charts of FIGS. The flowchart of FIG. 2 shows a synchronization process for determining the PWM period and the duty ratio and synchronizing the PWM period and the A / D conversion interval. The flowchart of FIG. 3 shows a subroutine for calculating the PWM period. The flowchart of FIG. 4 shows a subroutine for calculating the duty ratio of the PWM signal.

  In the present embodiment, as will be described in detail later, actual current detection is performed a plurality of times (for example, four times) during one PWM cycle. In the synchronization process of FIG. 2, the duty ratio of the PWM signal is calculated based on the average current corresponding to the average of the actual current values obtained by the multiple actual current detections, and the oil temperature of the hydraulic oil The PWM period is calculated based on the above.

  As described above, in the synchronization processing shown in FIG. 2, in addition to the synchronization between the PWM cycle and the A / D conversion interval, the cycle and duty ratio of the next PWM signal are set. It is set based on the timing (A / D conversion execution timing). More specifically, the start timing of the synchronization processing in FIG. 2 is determined by the actual current detection timing excluding the actual current detection timing immediately before the end of the PWM cycle. For example, in the timing chart of FIG. 6, actual current detection is performed four times during one PWM period, and the synchronization processing of FIG. 2 is started in accordance with the second actual current detection timing. An example is shown. As described above, the actual current detection timing excluding the actual current detection timing immediately before the end of the PWM cycle is set as the synchronization processing start timing in FIG. 2, so that an appropriate timing can be obtained without using a dedicated timer. Synchronous processing can be started. As a result, in the next PWM cycle, the PWM signal according to the cycle and the duty ratio determined in the synchronization process shown in FIG. 2 can be reliably output.

  In the timing chart of FIG. 6, an example is shown in which the synchronization process is started in synchronization with the second actual current detection timing. However, when the number of actual current detections is 4, the synchronization processing can be started in accordance with the first or third actual current detection timing other than the fourth actual current detection timing.

  Hereinafter, the synchronization process shown in the flowchart of FIG. 2 will be described. First, in step S100, the next PWM cycle is calculated. That is, the process of step S100 corresponds to the period setting means described in the claims.

  The calculation of the next PWM cycle will be described with reference to the flowchart of FIG. First, in step S200, the oil temperature of the hydraulic oil whose hydraulic pressure is controlled by the hydraulic control valve is detected. That is, as described above, the detection signal from the temperature sensor is input, and the temperature of the hydraulic oil is calculated based on the detection signal. Next, in step S210, the next PWM cycle is calculated according to a predetermined function or map based on the detected oil temperature.

  The reason for calculating the PWM period based on the oil temperature in this way is that the viscosity of the hydraulic oil changes according to the oil temperature, and as a result, the responsiveness for changing the oil pressure changes. Specifically, the lower the oil temperature, the higher the viscosity of the hydraulic oil, so it takes time for the hydraulic oil to flow. Therefore, the lower the oil temperature, the longer the PWM cycle. Then, the PWM cycle is changed so that the PWM cycle becomes shorter as the oil temperature rises. In this way, by changing the PWM cycle according to the change in the oil temperature, it is possible to perform highly accurate hydraulic control regardless of the change in the viscosity of the hydraulic oil.

  Note that the PWM cycle may be switched to two stages according to the oil temperature, or may be switched to three or more stages. Furthermore, the PWM cycle may be changed according to the change in the target current value to be passed through the linear solenoid 100 as in the prior art.

  In subsequent step S110, the A / D conversion interval is calculated based on the next PWM cycle calculated in step S100. That is, the A / D conversion interval is calculated so that the change in the PWM cycle and the change in the A / D conversion interval are synchronized. The processing in step S110 corresponds to the interval setting means described in the claims.

  In the present embodiment, as described above, the PWM cycle is changed depending on the oil temperature of the hydraulic oil. Even if the PWM cycle is changed, if the interval of the actual current detection timing (that is, the A / D conversion interval) remains constant, the number of detections of the actual current value per cycle of the PWM cycle may vary. Sex occurs. As a result, due to fluctuations in the number of actual current value detections, the actual current value detection accuracy may decrease, leading to a decrease in PWM control accuracy.

Therefore, in the present embodiment, as described above, in step S110, based on the next PWM cycle T _{n + 1} calculated in step S100 and the current PWM cycle T _n , the A / D conversion interval T _{A / D} is calculated. Specifically, the A / D conversion interval T _{A / D} is calculated by the following formula 1.
(Equation 1)
T _{A / D} = {(T _n + T _{n + 1} ) / 2} / N
N is the number of actual current detections per PWM cycle.

By performing actual current detection according to the A / D conversion interval T _{A / D} calculated by Equation 1, even if the PWM cycle is changed, the number of detections of the actual current per PWM cycle can be kept constant. .

  A specific example of calculating the A / D conversion interval will be described with reference to the timing chart of FIG. FIG. 6 shows an example in which the PWM cycle is changed from 1000 μs to 880 μs.

When the PWM period continues to be 1000 μs, the actual current is detected four times during the period from the execution of the synchronization process in the current PWM period until the execution of the synchronization process in the next PWM period, that is, 1000 μs. From Equation 1, the A / D conversion interval T _{A / D} is calculated as 250 μs.

When a PWM cycle Tn + 1 (880 μs) different from the previous PWM cycle Tn (1000 μs) is calculated by the synchronization process x, the A / D conversion interval is calculated by Equation 1 in order to cope with the change in the PWM cycle. T _{A / D} is calculated as 235 μs. In this case, the interval from the execution timing of the synchronization process in the current PWM cycle Tn to the execution timing of the synchronization process in the next PWM cycle Tn + 1 is 980 μs. Therefore, by performing actual current detection according to the A / D conversion interval of 235 μs, it is possible to perform actual current detection four times during the 980 μs.

After the next PWM cycle Tn + 1, when the PWM cycle length is stabilized at 880 μs, the A / D conversion interval T _{A / D} is calculated by Equation 1 as 220 μs. Therefore, also in this case, the actual current can be detected four times from the execution of the synchronization process in the current PWM cycle to the execution of the synchronization process in the next PWM cycle.

  As a result, in the present embodiment, as shown in FIG. 6, even if the PWM period is changed, it is possible to always perform a certain number of actual current detections during one period of the PWM period.

  In the subsequent step S120, the A / D conversion interval calculated in step S110 is set in the A / D conversion unit 22. As a result, the A / D converter 22 performs A / D conversion (detection of actual current value) for a predetermined number of times (four times in the example shown in FIG. 6) according to the newly set A / D conversion interval. It will be.

  In the next step S130, the duty ratio is calculated. That is, the processing in step S130 corresponds to the duty ratio setting means described in the claims. The calculation of the duty ratio will be described with reference to the flowchart of FIG.

  First, in step S300, a target current value is calculated from the target hydraulic pressure. Next, in step S310, the dither target current value is calculated by adding or subtracting the dither current in accordance with the dither cycle to the target current value calculated in step S300. That is, as shown in the timing chart of FIG. 5, by periodically adding and subtracting the dither current diza with respect to the target current value I according to the dither cycle (10 ms), the dither target current value that varies periodically is calculated. To do.

  Thus, the plunger can be minutely vibrated in the stroke direction by changing the target current value according to the dither cycle. As a result, the frictional resistance can be reduced and the response of the plunger stroke can be improved as compared with the case where the plunger is stroked from the stationary state.

  In the subsequent step S320, a current deviation between the target current and the actual current for the dither cycle is calculated. A specific method for calculating the current deviation will be described below.

  In the present embodiment, the actual current value is detected every A / D conversion interval by the A / D conversion unit 22, and the detection result is stored in the calculation unit 24. In step S320, first, the average current is calculated by averaging the actual currents for the number of actual current detections per period of the PWM cycle before the start of the synchronization process. Therefore, the calculated average current is an average of the actual current values detected in a period corresponding to the length of one PWM period. The calculated average current is further averaged by the dither period, thereby calculating the average value of the actual current in the length of the dither period.

  For example, in the example shown in FIG. 5, the PWM cycle is 1 ms, and the average current of the above-described actual current is calculated every 1 ms. However, since the calculation of the average current of the actual current is performed in the middle of the PWM cycle, the actual current value that is the target of the average current calculation is a mixture of those detected between the previous PWM cycle and the current PWM cycle. Will do. In the example shown in FIG. 5, the dither cycle is 10 ms. Accordingly, by obtaining an average value of 10 average currents calculated every 1 ms, the average value of the actual currents in the length of the dither cycle can be obtained.

  Next, an average value of a corrected target current, which will be described later, for the same dither cycle length is calculated. Then, a difference between the average value of the actual current and the average value of the corrected target current in the length corresponding to the dither cycle is calculated as a current deviation.

  When performing the above-described calculation, first, the integrated value of the actual current value for the dither cycle and the integrated value of the corrected target current are obtained, the difference between these integrated values is calculated, and then the difference is calculated as a predetermined coefficient. The current deviation may be obtained by dividing by.

  The current deviation calculated in this way indicates an error between the actual current and the target current. Therefore, in order to correct the error, in step S340, the current deviation is set as a correction value (hosei), the dither target current is corrected, and the corrected target current is calculated.

  In subsequent step S350, PID calculation (feedback calculation) is performed using the corrected target current calculated in step S340 and the average current obtained by averaging the actual currents for the number of times of actual current detection per one period of the PWM cycle. And calculate the duty ratio of the PWM signal. That is, the duty ratio of the PWM signal is calculated based on the proportional term, the integral term, and the derivative term relating to the difference between the correction target current and the average current. Thus, the duty ratio of the PWM signal that can control the switching element 12 can be determined so that the current flowing through the linear solenoid 100 follows the target current.

  When the process of step S130 is completed, the process of step S140 is executed. In step S140, the calculated PWM cycle and duty ratio are set in the register of the PWM signal output unit 26. Thereby, the PWM signal output unit 26 can generate and output a PWM signal according to the period and the duty ratio stored in the register when the next PWM period is started.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the start timing of the synchronization processing in FIG. 2 is set based on the actual current detection timing (A / D conversion execution timing). However, the start timing of the synchronization processing in FIG. 2 may be set based on the elapsed time from the start of the PWM cycle.

  A specific example of processing in the case where the start timing of the synchronization processing is set based on the elapsed time from the start of the PWM cycle will be described with reference to the flowchart of FIG.

  First, in step S400, it is determined whether or not a rising edge of the PWM signal has appeared. Since the time when the rising edge of the PWM signal appears is the start of a new PWM cycle, when it is determined that the rising edge has appeared, the process proceeds to step S410. On the other hand, when the rising edge does not appear, the process waits until the rising edge appears by repeatedly executing step S400.

  In step S410, the execution time of the synchronization process of FIG. 2 is calculated. Specifically, the execution time is calculated as an elapsed time from the start of the PWM cycle, and the elapsed time is calculated by dividing the new PWM cycle by 2. However, the execution time of the synchronization processing may be calculated by dividing by a numerical value larger than “1” and other than “2”.

  In the subsequent step S420, the calculated execution time (elapsed time) is set in a timer (not shown). In step S430, it is determined whether or not the synchronization processing execution time has come. When it is determined that the synchronization process execution time has arrived, the execution of the synchronization process in FIG. 2 is started.

  Even in this case, it is possible to start execution of the synchronization process at an appropriate timing at which the PWM cycle and the duty ratio calculated by the synchronization process can be reflected in the PWM signal of the next PWM cycle.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the example in which the dither cycle is set to be longer than the PWM cycle has been described. However, the length of the dither cycle may be set to be equal to or longer than the PWM cycle.

DESCRIPTION OF SYMBOLS 10 ... Load drive control apparatus 12 ... Switching element 14 ... Microcomputer 16 ... Current detection part,
DESCRIPTION OF SYMBOLS 18 ... Resistance 20 ... Operational amplifier 22 ... A / D conversion part 24 ... Operation part 26 ... PWM signal output part 100 ... Linear solenoid

Claims (9)

A load drive control device for controlling driving of an inductive load (100), comprising:
Switching means (12) provided on the energization path of the inductive load and energizing the inductive load with a current having a magnitude corresponding to the duty ratio of the duty signal by turning on and off according to a given duty signal When,
An actual current value detecting means (16) for detecting an actual current value of the inductive load;
Based on the deviation between the target current value of the inductive load and the actual current value detected by the actual current value detecting means, the duty of the duty signal is adjusted so that the actual current value follows the target current value. Duty ratio setting means (S130) for setting the ratio;
Period setting means (S100) for setting the period length of the duty signal;
A duty signal generating means (26) for generating a duty signal in accordance with the length of the period set by the period setting means and the duty ratio set by the duty ratio setting means and giving the duty signal to the switching means; ,
The actual current value detecting means detects the actual current value a plurality of times during one period of the duty signal, and the duty ratio setting means averages the actual current value detected a plurality of times. An actual current value corresponding to the current is calculated, and the duty ratio is set using the actual current value corresponding to the average current,
Further, even if the period of the duty signal is varied by the period setting means in synchronization with the period length of the duty signal being set by the period setting means, A load drive control device comprising: interval setting means (S110) for setting an interval at which the actual current value detecting means detects the actual current so as to keep the number of current detections constant. The inductive load is a solenoid of a hydraulic control valve that adjusts hydraulic pressure of hydraulic oil,
The load drive control device according to claim 1, wherein the cycle setting means sets the cycle of the duty ratio based on an oil temperature of the hydraulic oil. The cycle setting means sets a cycle length of the next duty signal at a predetermined timing for each cycle of the duty signal,
3. The load drive control according to claim 1, wherein the interval setting unit sets the detection interval of the actual current from the predetermined timing in the current cycle to the predetermined timing in the next cycle. apparatus. The load drive control device according to claim 3, wherein the interval setting unit calculates an actual current detection interval T according to Equation 1 below.
(Equation 1)
T = {(T _n + T _{n + 1} ) / 2} / N
Here, T _n is the current duty signal cycle, T _{n + 1} is the next duty signal cycle, and N is the number of actual current detections per cycle of the duty signal cycle.   4. The load drive control according to claim 3, wherein the predetermined timing is determined based on the detection timing of the actual current excluding the detection timing of the actual current immediately before the cycle of the duty signal ends. apparatus. A timer means for measuring time,
4. The load drive control device according to claim 3, wherein the predetermined timing is determined based on an elapsed time measured by the timer unit and starting from a cycle of the duty signal.   7. The target current value is repeatedly increased and decreased around a current value to be targeted in a dither cycle having a length equal to or longer than the cycle of the duty signal. The load drive control apparatus of any one of Claims. A deviation calculating means for calculating a dither average actual current value corresponding to the average current of the actual current value for the dither cycle, and calculating a deviation between the dither average actual current value and the target current value. S320),
The load drive control device according to claim 7, further comprising a correction unit (S330) that corrects the target current value by using the deviation calculated by the deviation calculation unit.   The load according to claim 8, wherein the deviation calculating unit calculates the deviation for each period corresponding to a period of the duty signal, and the correction unit updates the correction of the target current value. Drive control device.

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