JP3806701B2 - Current control device and current control method for actuator for electronic governor of engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current control device and current control method for an electronic governor actuator of an engine, and more particularly, to a current control device and current control method for an electronic governor actuator of a type in which a dither signal is superimposed on a PWM signal to drive the actuator. About.
[0002]
[Prior art]
Conventional electronic governors for engine speed control include those described in Patent Document 1 or 2. According to these conventional technologies, a fuel metering rack (in the case of a diesel engine) or a throttle valve (in the case of a spark ignition engine) provided in a fuel injection pump according to the deviation between the actual engine speed and the target engine speed. The fuel supply amount adjusting means such as the above is driven by an actuator, thereby controlling the fuel injection amount so that the deviation between the actual engine speed and the target engine speed falls within an allowable range.
[0003]
At that time, as described in Patent Document 2, a minor loop for current feedback is provided in the loop for feeding back the engine speed, and the energization current value (excitation current value) to the actuator is set as the command current. Generally, the responsiveness is improved by matching the value.
[0004]
In addition, in order to reduce the influence of hysteresis characteristics of an electromagnetic actuator such as a solenoid, a dither signal is superimposed on an operation signal such as a PWM signal to slightly vibrate the actuator (see Patent Document 3).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-062663 [Patent Document 2]
JP 2000-104605 A [Patent Document 3]
Japanese Patent Laid-Open No. 2001-020789
[Problems to be solved by the invention]
However, when a dither signal is superimposed on an operation signal such as a PWM signal, the actuator's energizing current also includes a disturbance called dither, so the detected current value itself fluctuates due to the dither, and the control system is unnecessary. May destabilize.
[0007]
In particular, an electronic governor that indirectly detects the position of an object to be driven, such as a fuel metering rack driven by an actuator, based on the value of the current applied to the actuator, can achieve low costs by eliminating the need for an expensive rack position sensor. Although it is possible, since more accurate current value detection is required, fluctuations in the detected current value due to the dither signal cause a reduction in control accuracy.
[0008]
[Means for Solving the Problems]
In order to solve the problem, the present invention is configured as follows.
According to the first aspect of the present invention, the current detection means (8) for detecting the current flowing to the actuator (2) and the deviation between the detected current value detected by the current detection means (8) and the command current value are allowed. Current feedback control means (7) for controlling the energization amount of the actuator (2) based on the PWM signal so as to fall within the range, and for the electronic governor of the engine in which the dither signal is superimposed on the PWM signal In the current control device for the actuator, the signal cycle of the dither signal is set to a length not less than three times the signal cycle of the PWM signal, and the current detection means (8) detects the current flowing to the actuator (2). And a detection unit (81) for outputting a current detection signal, and based on the current detection signal from the detection unit (81), the communication to the actuator (2) per cycle of the PWM signal is performed. The amount of electricity is calculated, and at least for one period of the dither signal, each energization amount per period of the PWM signal is stored, and the maximum value and the minimum value are detected from the energization amounts for one period of the dither signal. The average value of the energization amount for one period of the dither signal excluding the maximum value and the minimum value is calculated, and this average value is output as the detected current value to the current feedback control means (7). Features.
[0009]
In the first aspect of the invention, since the dither signal period is set to a length of three times or more of the PWM signal period, the energization amount of the actuator (2) per one PWM signal period in one dither signal period. Both the influence of dithering in the direction of increasing the amount of current and the influence of dithering in the direction of decreasing the amount of energization of the actuator (2) appear. Therefore, according to the first aspect of the present invention, the maximum value and the minimum value of the energization amount at which the influence appears most are removed from the energization amounts for one cycle of the dither signal where the influence of the dither signal appears. The average value of the energization amount of the actuator was calculated, and this average value was used as the detected current value for current control of the actuator (2). For this reason, it is possible to suppress fluctuations in the detected current value due to dithering while maintaining the dithering effect of reducing hysteresis, and to improve the control performance of the current control of the actuator (2). In addition, since the position of a driving object such as a fuel metering rack can be accurately detected based on the value of the current supplied to the actuator (2), an expensive rack position sensor can be omitted.
[0010]
In the case of current control using the PWM method, even if the command current value changes, a delay of one cycle of the PWM signal occurs at a maximum until the change in the command current value is reflected in the PWM signal. For this reason, if the PWM signal cycle is long, the responsiveness may be lacking. On the other hand, if the dither signal cycle is short, the movable part of the actuator (2) becomes difficult to follow, so that a suitable dither effect may not be obtained. Therefore, as described in claim 1, it is technically significant to set the signal cycle of the dither signal longer than the signal cycle of the PWM signal.
[0011]
The invention described in claim 1 is preferably configured as described in claim 2.
That is, the current detection means (8) A / D converts the current detection signal output from the detection unit (81) at a cycle shorter than the PWM signal, and converts the current detection signal into the A / D converted current detection signal. On the basis of this, the average energization amount to the actuator (2) per one cycle of the PWM signal is calculated, and each average energization amount per one cycle of the PWM signal is stored at least for one cycle of the dither signal, and one cycle of the dither signal The maximum value and the minimum value are detected from the average energization amount for each minute, and the average value of the average energization amount for one cycle of the dither signal excluding the maximum value and the minimum value is calculated. Is output to the current feedback control means (7) as a detected current value.
[0012]
According to a third aspect of the present invention, in the current control device for an actuator for an electronic governor of the engine according to the first or second aspect, the signal cycle of the dither signal is n times the signal cycle of the PWM signal (n is 3 or more). Natural number). Accordingly, it is possible to calculate a more accurate detected current value by removing the influence of the dither signal from the energization amount of the actuator (2).
[0013]
According to a fourth aspect of the present invention, in the current control device for an actuator for an electronic governor of an engine according to any one of the first to third aspects, the command current value to the actuator (2) is the actual engine speed. The rotational speed feedback control means (6) for determining the energization amount to the actuator (2) is set so that the deviation from the target rotational speed is within an allowable range.
[0014]
As described above, in each of the inventions according to the first to third aspects, since the fluctuation of the detected current value due to dither can be suppressed, the position of the driving object such as the fuel metering rack is set to the energization of the actuator (2). It can be detected more accurately by the current value. Therefore, as described in claim 4, if the command current value to the actuator (2) is configured as a control amount of the rotation speed feedback control means (6), a loop for feeding back position information of the fuel metering rack or the like Need not be provided again, and the control system can be simplified by omitting the rack position sensor. Further, the cost can be reduced because the rack position sensor becomes unnecessary.
[0015]
According to the fifth aspect of the present invention, the energization amount of the actuator (2) is PWM detected so that the energization current to the actuator (2) is detected and the deviation between the detected current value and the command current value is within an allowable range. In the current control method for the actuator for the electronic governor of the engine, in which feedback control is performed based on the signal and a dither signal is superimposed on the PWM signal, the following configuration is provided.
That is, the signal cycle of the dither signal is set to a length that is at least three times the signal cycle of the PWM signal. The step of detecting the energization current to the actuator (2) and outputting a current detection signal, and the amount of energization to the actuator (2) per cycle of the PWM signal are calculated based on the current detection signal. A step of storing each energization amount per period of the PWM signal and detecting a maximum value and a minimum value among the energization amounts for one period of the dither signal for at least one period of the dither signal; And a step of calculating an average value of the energization amount for one period of the dither signal excluding the maximum value and the minimum value, and a step of feeding back the average value as a detected current value. To do.
[0016]
In the invention according to the fifth aspect, the maximum value and the minimum value of the energization amount at which the influence appears most are excluded from the energization amounts for one cycle of the dither signal where the influence of the dither signal appears. Since the average value of the energization amount is calculated and this average value is used as the detected current value for the current control of the actuator (2), the fluctuation of the detected current value due to dithering is suppressed while the effect of dithering is reduced. can do. Thereby, the control performance of the current control of the actuator (2) is improved. In addition, since the position of a driving object such as a fuel metering rack can be accurately detected based on the value of the current supplied to the actuator (2), an expensive rack position sensor can be omitted.
[0017]
The invention described in claim 5 is preferably configured as described in claim 6.
That is, based on the step of A / D converting the current detection signal in a cycle shorter than that of the PWM signal and the current detection signal subjected to the A / D conversion, to the actuator (2) per cycle of the PWM signal. A step of calculating an average energization amount of the dither signal, a step of storing each average energization amount per cycle of the PWM signal, and at least one of the average energization amounts for one cycle of the dither signal. A step of detecting the maximum value and the minimum value, a step of calculating an average value of the average energization amount for one cycle of the dither signal excluding the maximum value and the minimum value, and feeding back the average value as a detected current value Preferably, a step is provided.
[0018]
According to a seventh aspect of the present invention, in the current control method for an actuator for an electronic governor of the engine according to the fifth or sixth aspect, the signal cycle of the dither signal is n times the signal cycle of the PWM signal (n is 3 or more). Natural number). Accordingly, it is possible to calculate a more accurate detected current value by removing the influence of the dither signal from the energization amount of the actuator (2).
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a rotational speed control system 1 (electronic governor) for a diesel engine according to an embodiment of the present invention. This diesel engine speed control system 1 drives a fuel metering rack (not shown) provided in a fuel injection pump (not shown) of a diesel engine by a solenoid 2 (actuator 2) to target the engine speed. The target rotational speed setting means 3 such as a speed control lever, the actual rotational speed detection means 4 that is a rotational speed sensor such as an electromagnetic pickup, and the solenoid 2 (actuator 2) that drives the fuel metering rack. ) And ECU 5.
[0020]
The ECU 5 includes a rotation speed feedback control unit 6, a current feedback control unit 7, and a current detection unit 8. In the present embodiment, the rotation speed feedback control unit 6 functions as a rotation speed feedback control unit, and the current feedback control unit 7 functions as a current feedback control unit.
[0021]
The ECU 5 incorporates a clock signal generator 9 and performs various calculations and control operations based on a reference clock signal (clock frequency f: 200 Hz) generated by the clock signal generator 9.
[0022]
The rotation speed feedback control unit 6 includes a rotation speed deviation calculating means 61 and a command current value calculating means 62. The rotational speed deviation calculating means 61 calculates the deviation between the actual engine speed from the actual engine speed detecting means 4 and the target engine speed set by the target engine speed setting means 3. The command current value calculation means 62 outputs a command current value to the actuator 2 so that the rotation speed deviation calculated by the rotation speed deviation calculation means 61 falls within an allowable range. The command current value calculation means 62 is based on PID control. Is calculated. However, the present invention is not limited to normal PID control, and differential preceding PID control and other control methods may be used.
[0023]
The current feedback control unit 7 includes a current value deviation calculating unit 71, an operation amount calculating unit 72, a PWM signal output unit 73, and a driving unit 74. Among these, the current value deviation calculating means 71 calculates the deviation between the two based on the detected current value detected by the current detecting means 8 described later and the command current value from the rotational speed feedback control unit 6. The operation amount calculation means 72 calculates the duty ratio (operation amount) of the PWM signal so that the current value deviation calculated by the current value deviation calculation means 71 falls within the allowable range. The operation amount calculation means 72 calculates the duty ratio based on PID control. It comes to calculate. The PWM signal output means 73 outputs a PWM signal based on the duty ratio calculated by the operation amount calculation means 72 and a dither signal output by a dither signal output means described later. The PWM signal (cycle T) output by the PWM signal output means 73 is synchronized with the reference clock signal (clock frequency f: 200 Hz) and has a relationship of T = 1 / f (= 5 msec). The driving means 74 includes a switching element (not shown), and drives the solenoid 2 (actuator 2) by turning on and off the switching element based on the PWM signal output from the PWM signal output means 73.
[0024]
The current feedback control unit 7 also includes dither signal output means 75. This dither signal output means 75 is used to slightly vibrate the movable part in order to reduce the hysteresis of the actuator 2 such as a solenoid and the frictional resistance of the sliding part, and divides the reference clock signal by 1/6. Generated pulse signal (dither signal). Specifically, the dither signal output means 75 intermittently outputs two positive and negative pulses having a predetermined pulse width within one period (6T = 30 msec).
[0025]
The PWM signal output means 73 generates and outputs a PWM signal on which the dither signal is superimposed. That is, by adding or subtracting the pulse width of the dither signal generated by the dither signal output means 75 to the duty ratio calculated by the operation amount calculation means 72, the duty ratio after the dither signal is superimposed is calculated, and this dither signal A PWM signal is generated based on the duty ratio after superposition. Therefore, among the six PWM signals output by the PWM signal output means 73 during the dither signal period 6T, the pulse width of the dither signal is added to increase the duty ratio, and the pulse width of the dither signal is Some of them are subtracted to reduce the duty ratio.
[0026]
The processing procedure of this dither signal superposition is as shown in FIG. As described above, during one cycle (6T) of the dither signal, the manipulated variable calculation means 72 calculates six times to calculate six duty ratios. Therefore, a counter (loop counter) is provided that counts up every time the operation amount calculation means 72 calculates the duty ratio, and this loop counter calculates the number of times of one cycle of the dither signal by this loop counter. To indicate whether or not In step S201, the loop counter is initialized, and in step S202, the operation amount calculation means 72 calculates the duty ratio duty. In step S203, it is determined how many times the current duty ratio calculation corresponds to one cycle of the dither signal. If it is determined in this step S203 that this time is the third duty ratio calculation (loop counter = 2) (in the case of “YES”), the process proceeds to step S204, and the dither signal is added to the duty ratio duty calculated in step S202. A PWM signal is generated by newly adding the pulse width dither to the duty ratio duty. On the other hand, if “NO” in the step S203, it is determined whether or not the current duty ratio calculation corresponds to the sixth duty ratio calculation (loop counter = 5) in a step S205. In the case of “YES”, in step S206, a PWM signal is generated by newly subtracting the pulse width dither of the dither signal from the duty ratio duty calculated in step S202 as a duty ratio duty, and a loop counter To reset. On the other hand, in the case of “NO”, the loop counter is incremented, and the process returns to step S202 to calculate the next duty ratio. Note that a step of performing a limiter process for limiting the value of the duty ratio within a certain range may be provided after step S202, step S204, and step S206.
[0027]
The current detection means 8 of this embodiment includes a shunt resistor 81 as a detection unit, an A / D converter 82, and a detection current value calculation means 83. The A / D converter 82 is for A / D conversion of the current detection signal (voltage) from the detection unit 81, and operates at a frequency 32f obtained by multiplying the reference clock frequency f by 32 times. It has become. Therefore, the A / D converter 82 performs A / D conversion 32 times during one period of the PWM signal.
[0028]
The detected current value calculation means 83 calculates the average current per cycle of the PWM signal based on the average current value calculation routine shown in FIG. 3 from the value after the A / D conversion (hereinafter referred to as “A / D value”). Calculate the value. Specifically, first, a counter that counts the number of A / D conversions and a variable V _sum that represents the sum of A / D values are prepared. In step S301, V _sum is initialized. In step S302, the current detection signal (voltage) from the shunt resistor 81 (detection unit 81) is A / D converted. In step S303, the _sum of this A / D value and V _sum is newly set as V _sum, and in step S304, the counter is incremented. In step S305, it is determined whether or not the counter value has become 32. If it is less than 32 (in the case of “NO”), the process returns to step S302. On the other hand, when the value of the counter reaches 32 (in the case of “YES”), an average voltage V _ave per PWM signal cycle is calculated in step S306. In step S307, the average voltage V _ave per PWM signal cycle is subjected to voltage / current conversion to calculate an average current value I _ave per PWM signal cycle. In step S308, the counter is cleared, and the process returns to step S301.
[0029]
Detection current value calculating means 83, the average current value I _ave of the PWM signal 1 cycle per thus obtained, according to the flowchart shown in FIG. 4, calculates the detected current value I _r. First, a storage area for an array I [n] (n = 0 to 5) for storing the average current value I _ave per one cycle of the PWM signal is secured in a memory space (RAM) (not shown). In this array I [n] (n = 0 to 5), the average current value per cycle of the PWM signal is stored for one cycle of the dither signal. In step S401 to step S404, the average current value per cycle of the PWM signal stored in the array is shifted one by one, and in step S405, the latest average current value I _ave is stored in I [0]. In step S406, a total I _sum of average current values I _ave per one PWM signal period for one period of the dither signal is calculated. In step S407 and step S408, the maximum value and the minimum value of the average current value I _ave stored in the array I [n] (n = 0 to 5) are obtained. In step S409, the obtaining an average value _{I r,} except the maximum value and the minimum value from the _{I sum.} The I _r is between dither signal one period 6T, from the average current value I _ave of the PWM signal per period T, which is energized to the actuator 2 by the PWM signal, those most affected by the dither signal Except for this, the arithmetic average value of the energization amount for one cycle of the dither signal is obtained.
[0030]
Detection current value calculating means 83, a detected current value arithmetic mean value I _r of the thus obtained dither signal one period of the actuator 2 energization amount, and outputs to the current feedback control unit 7. Current feedback control unit 7, and the detected current value I _r, compares the command current value command current value computing means 62 is set by the revolution speed feedback control section 6, so as to accommodate the deviation between within the permissible range , The duty ratio of the PWM signal is calculated, and the actuator 2 is driven.
[0031]
As described above, according to the present embodiment, the energization amount having a significant influence is excluded from the energization amounts corresponding to one cycle of the dither signal in which the influence of the dither signal appears, and between them, Since the arithmetic average of the energization amount is calculated and this arithmetic average value is used as the detected current value for the current control of the actuator 2, the dithering effect of reducing the hysteresis is kept, and the fluctuation of the detected current value due to the dither is suppressed. Thus, the control performance of the current control of the actuator 2 can be improved. In addition, since the position of the fuel metering rack can be accurately detected based on the value of the current supplied to the actuator 2, an expensive rack position sensor can be omitted.
[0032]
As mentioned above, although embodiment of this invention was described, this invention is not restricted to the said embodiment, It can change suitably within the range of the summary of invention, and can implement. In the above embodiment, the command current value calculation means 62 of the rotation speed feedback control unit 6 and the operation amount calculation means 72 of the current feedback control unit 7 are configured as PID control elements, but not only normal PID control, You may comprise as a differential precedence type PID and other types of control elements. In the above embodiment, the dither signal output means 75, the PWM signal output means 73, and the A / D converter 82 are configured to operate based on the clock signal from the same clock signal generator 9, but different clock sources. It is also possible to configure each to operate based on the signal from. In the above embodiment, the average energization amount of the actuator per cycle of the PWM signal and the average value of the energization amount per cycle of the PWM signal for one cycle of the dither signal are obtained by arithmetic averaging, but not limited to the arithmetic average, You may obtain | require by the other average concept. In the above embodiment, the average energization amount of the actuator per PWM signal cycle is calculated from the average value obtained by performing A / D conversion 32 times within one cycle of the PWM signal for the current detection signal (voltage) generated by the detection unit. However, the calculation method is not limited to this. For example, the current detection signal (voltage) may be smoothed by an analog filter, and the smoothed signal may be A / D converted to obtain an average current value.
[Brief description of the drawings]
FIG. 1 is a block diagram of a diesel engine speed control system (electronic governor) according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a dither signal superimposition process.
FIG. 3 is a flowchart for calculating an average energization amount to the actuator per PWM signal cycle.
FIG. 4 is a flowchart for calculating a detected current value.
[Explanation of symbols]
2 ... Solenoid (actuator)
6 ... Rotation speed feedback control section (rotation speed feedback control means)
7. Current feedback control unit (current feedback control means)
8 ... Current detection means
81 ... Shunt resistor (detection part)

Claims (7)

The current detection means (8) for detecting the energization current to the actuator (2), and the actuator (8) so that the deviation between the detected current value detected by the current detection means (8) and the command current value is within an allowable range. 2) current feedback control means (7) for controlling the energization amount based on the PWM signal;
In the current control device for an actuator for an electronic governor of an engine, in which a dither signal is superimposed on the PWM signal,
The signal cycle of the dither signal is set to a length that is at least three times the signal cycle of the PWM signal,
The current detection means (8)
A detection unit (81) for detecting an energization current to the actuator (2) and outputting a current detection signal;
Based on the current detection signal from the detection unit (81), the amount of energization to the actuator (2) per one cycle of the PWM signal is calculated,
Each energization amount per one period of the PWM signal is stored for at least one period of the dither signal,
The maximum value and the minimum value are detected from the energization amounts for one cycle of the dither signal,
Calculate the average value of the energization amount for one cycle of the dither signal excluding the maximum and minimum values,
The average value is output as the detected current value to the current feedback control means (7).
A current control device for an actuator for an electronic governor of an engine. The current detection means (8) for detecting the energization current to the actuator (2), and the actuator (8) so that the deviation between the detected current value detected by the current detection means (8) and the command current value is within an allowable range. 2) current feedback control means (7) for controlling the energization amount based on the PWM signal;
In the current control device for an actuator for an electronic governor of an engine, in which a dither signal is superimposed on the PWM signal,
The signal cycle of the dither signal is set to a length that is at least three times the signal cycle of the PWM signal,
The current detection means (8)
A detection unit (81) for detecting an energization current to the actuator (2) and outputting a current detection signal;
The current detection signal output by the detection unit (81) is A / D converted at a cycle shorter than the PWM signal,
Based on the A / D converted current detection signal, an average energization amount to the actuator (2) per one cycle of the PWM signal is calculated,
At least for one period of the dither signal, each average energization amount per period of the PWM signal is stored,
The maximum value and the minimum value are detected from the above average energization amounts for one cycle of the dither signal,
Calculate the average value of the average energization amount for one cycle of the dither signal excluding the maximum and minimum values,
The average value is output as the detected current value to the current feedback control means (7).
A current control device for an actuator for an electronic governor of an engine. In the current control device for an actuator for an electronic governor of an engine according to claim 1 or 2,
The signal cycle of the dither signal is set to n times the signal cycle of the PWM signal (n is a natural number of 3 or more),
A current control device for an actuator for an electronic governor of an engine. In the current control device for an actuator for an electronic governor of an engine according to any one of claims 1 to 3,
The command current value to the actuator (2) is a rotational speed feedback control means (6) that determines the amount of current supplied to the actuator (2) so that the deviation between the actual rotational speed of the engine and the target rotational speed is within an allowable range. )
A current control device for an actuator for an electronic governor of an engine. An energization current to the actuator (2) is detected, and the energization amount of the actuator (2) is feedback-controlled based on the PWM signal so that the deviation between the detected current value and the command current value is within an allowable range.
In the current control method of an engine electronic governor actuator, wherein a dither signal is superimposed on the PWM signal,
The signal cycle of the dither signal is set to a length that is at least three times the signal cycle of the PWM signal,
Detecting a current flowing to the actuator (2) and outputting a current detection signal;
Calculating an energization amount to the actuator (2) per cycle of the PWM signal based on the current detection signal;
Storing at least one energization amount per period of the PWM signal for at least one period of the dither signal;
Detecting a maximum value and a minimum value among the energization amounts for one cycle of the dither signal;
Calculating an average value of the energization amounts for one cycle of the dither signal excluding the maximum value and the minimum value;
Feeding back this average value as a detected current value,
A current control method for an actuator for an electronic governor of an engine. An energization current to the actuator (2) is detected, and the energization amount of the actuator (2) is feedback-controlled based on the PWM signal so that the deviation between the detected current value and the command current value is within an allowable range.
In the current control method of an engine electronic governor actuator, wherein a dither signal is superimposed on the PWM signal,
The signal cycle of the dither signal is set to a length that is at least three times the signal cycle of the PWM signal,
Detecting a current flowing to the actuator (2) and outputting a current detection signal;
A / D converting the current detection signal at a cycle shorter than the PWM signal;
Calculating an average energization amount to the actuator (2) per one period of the PWM signal based on the A / D converted current detection signal;
Storing at least one average energization amount per period of the PWM signal for at least one period of the dither signal;
Detecting a maximum value and a minimum value among the average energization amounts for one cycle of the dither signal;
Calculating an average value of the average energization amount for one cycle of the dither signal excluding the maximum value and the minimum value;
Feeding back this average value as a detected current value,
A current control method for an actuator for an electronic governor of an engine. In the electric current control method of the actuator for electronic governors of the engine according to claim 5 or 6,
The signal cycle of the dither signal is set to n times the signal cycle of the PWM signal (n is a natural number of 3 or more),
A current control method for an actuator for an electronic governor of an engine.

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