JPH0415411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque control method in a DC electric dynamometer such as a DC dynamometer.

Generally, a DC electric dynamometer, such as a DC dynamometer, is used to test the performance of engines, blowers, pumps, etc., and performs absorption operation to absorb power and driving operation. For example, in the performance test of an automobile engine, a dynamometer is directly connected to the engine.
Power is absorbed and driven using a dynamometer, and various engine performance tests are performed. In addition, if a chassis dynamometer is used to test the dynamic driving performance of a car indoors, a rotating drum is used as an infinite flat road instead of a road, and the dynamic test is carried out by placing the drive theory on the drum and driving it. conduct. In this case, the same load (running resistance) as when actually running on a road is applied to the drum shaft, and various measurements are performed under conditions as close as possible to actual running. A DC dynamometer is used as a device for applying this load.

If the capacity of the machine under test (size of the engine, etc.) is smaller than the capacity of the DC electric dynamometer in a test device that uses a DC electric dynamometer, perform the test by switching the torque detection range to one with a smaller capacity. That's what I do. This is done to improve torque detection accuracy.

Generally, to control the torque of a DC dynamometer, a method of controlling armature current and a method of controlling field current are used. In the method of controlling torque by controlling armature current, switching of the torque detection range is performed by an automatic control circuit of the armature current control system (for example, automatic control circuit 3 in FIG. 1).
The limiter value was changed to 1/2. Therefore, the rotational speed-torque characteristic simply changed from a solid line to a broken line as shown in FIG. 4b. Figure 4b
, the solid line indicates the case where the torque detection range is high, and the broken line indicates the case where the torque detection range is low. Also
No. to N ₁ indicates a constant torque control range, and N ₁ to _{N 2} indicate a constant output control range. As can be seen from FIG. 4b, the constant torque control range is the same No. to _N1 both when the torque detection range is in the high range (solid line) and in the low range (broken line), and there is no difference between the two. Therefore, the measurement range of the constant torque control range does not change in any way even if the torque detection range is switched.

The present invention was developed in view of the above points, and controls the field current by switching the control characteristics depending on whether the capacity of the machine under test is large or small, thereby making it possible to expand the constant torque control range. The purpose is to provide a torque control method in a DC electric dynamometer.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a DC dynamometer, and is a control block diagram. In FIG. 1, 1 is a speed or torque setting device, 2 is a speed or torque detection input and the setting device 1.
This is a first comparator that compares the outputs of the . The output of the first comparator 2 is sent to the second comparator 4 via an automatic control circuit 3 that performs constant speed control or constant torque control. This second comparator 4 compares the output current Ia of the first converter 6, which will be described later, with the current detected by the current transformer CTa and the output of the automatic control circuit 3. Second
The output of the comparator 4 is sent via the first constant current control circuit 5 to a control element of the first comparator 6, such as the gate of a thyristor. The first comparator 6 is controlled by the output of the first constant current control circuit 5, and supplies a predetermined current Ia to the armature 7 of the motor. It is assumed that a load such as a machine under test (not shown) is applied to the rotating shaft of the armature 7. The rotational speed of the armature 7 is detected by a pulse pickup 8,
The output is converted into a voltage by an F-V converter 9. The output of the F-V converter 9 is input to a pattern generating circuit 10 that changes the output current according to the rotation speed. This pattern generating circuit 10 is configured so that when the torque detection range is switched to a high range or a low range by manual or various computer commands, as will be described later, the rotation speed-current characteristic is switched at the same time. 10a is a changeover switch that changes the torque detection range. The output of the pattern generation circuit 10 is input to the third comparator 11, and the output current If of the second converter 13, which will be described later, is compared with the current detected by the current transformer CTf. The output of the third comparator 11 is sent via the second constant current control circuit 12 to a control element of the second converter 13, such as the gate of a thyristor. The second converter 13 is controlled by the output of the second constant current control circuit 12, and supplies a predetermined current to the field winding 14 of the motor.
If is supplied.

The details of the pattern generation circuit 10 are constructed as shown in FIG. In FIG. 2, 21 is a pattern generator to which the output of the F-V converter 9 is input. The output of this pattern generator 21 is input to an inverting amplifier 24 via a resistor 23. The output of this inverting amplifier 24 is input to the third comparator 11. Connected between the input and output terminals of the inverting amplifier 24 is a series circuit in which a diode 25 of the illustrated polarity, a relay contact 26, and a setting device 27 in which a current limit value is set are connected in series. 28 is a resistance. The pattern generator 21 has a function of switching to the rotation speed-current characteristic shown in FIG. 3a when the torque capacity of the test machine is in a high range, and switching to the characteristic shown by the solid line in FIG. 3b when it is in a low range. are doing.
Next, the operation of the device configured as described above and the torque control method will be described. If the torque capacity of the machine under test (not shown) currently applied to the rotating shaft of the armature 7 is in the high range, the selector switch 10a is switched to the high range side, and the rotation speed-current characteristic of the pattern generator 21 is The result is as shown in FIG. 3a. At this time, the output signal of the F-V converter 9 (an electrical signal proportional to the rotational speed of the armature 7) is input to the inverting amplifier 24 in accordance with the characteristics of the pattern generator 21. Here, in the straight line portion N ₀ to _{N 1} of the characteristic curve in FIG. First, it is limited by the setting value of the setting device 27. Thereafter, in the curved portion N ₁ to _{N 2} , that is, in the constant output control range, the relay contact 26 is opened, and the output of the pattern generator 21 is caused to pass through the inverting amplifier 24 . Next, when the torque capacity of the machine under test (not shown) is in the low range, the selector switch 10a is switched to the low range side, and the rotation speed-current characteristic of the pattern generator 21 is as shown by the solid line in FIG. 3b. become. At this time, in the straight line portion N ₀ -N ₁ ' in FIG. The setting value of the setting device 27 is used to limit the setting value. Thereafter, the relay contact 26 is opened in the same manner as described above in the curved portion N ₁ ' to N ₂ , that is, in the constant output control range, and the output of the pattern generator 21 is caused to pass through the inverting amplifier 24 . The output signal controlled by the pattern generation circuit 10 as described above is input to the control side of the second converter 13 via the third comparator and the second constant current control circuit 12, and the second converter 13 Supply magnetic current If. As a result, the rotation speed-horsepower characteristics are shown in Figure 4c.
The rotational speed-torque characteristic becomes as shown in FIG. 4d. Note that FIGS. 4a and 4b are characteristic diagrams when torque control is performed by controlling the armature current as in the prior art. Figure 4 a, b,
In c and d, the solid line shows the case of high range, and the broken line shows the case of low range. Figure 4b and Figure 4d
When compared, the characteristics in the low range at the rotation speed N ₁ to N ₂ in Figure 4b (the curve shown by the dashed line)
is deviated from the characteristic in the high range (the curve shown by the solid line). In the case of Fig. 4 d, the rotation speed N ₁ '~
Both characteristics are the same at N ₂ . This indicates that the constant torque control range is wider in the torque control method shown in FIG. 4d than in the torque control method shown in FIG. 4b when switching from the high range to the low range.

In addition, in the above-mentioned embodiment, the low range is 1/2 of the high range.

As described above, according to the present invention, the field current is controlled by switching the field control characteristics depending on whether the capacity of the test machine is large or small. The effect is that the control range can be made wider, and the measurement range of the constant torque control range of the DC electric dynamometer becomes wider.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 show one embodiment of the present invention, Fig. 1 is a configuration block diagram, Fig. 2 is a block diagram showing some details, and Fig. 3 a and b are rotation speed-current characteristic diagrams. , Figures 4a and 4b are the rotational speed-horsepower characteristic diagram and rotational speed-torque characteristic diagram when the armature current is controlled, and Figure 4c and d are the rotational speed-horsepower characteristic when the field current is controlled. and a rotation speed-torque characteristic diagram. DESCRIPTION OF SYMBOLS 1... Setting device, 2... First comparator, 3... Automatic control circuit, 4... Second comparator, 5... First constant current control circuit, 6... First converter, 7... Electric equipment child, 8...pulse pickup, 9...F-V converter, 10...pattern generation circuit, 10a...changeover switch, 11...third comparator, 12...second constant current control circuit, 13... ...Second converter, 1
4... Field winding, 21... Pattern generator, 2
3, 28...Resistor, 24...Inverting amplifier, 25...
...Diode, 26... Relay contact, 27...
Setting device.

Claims (1)

[Claims] 1. In a method of measuring various performances of a machine under test using a DC electric dynamometer equipped with a DC motor having an armature current control system and a field current control system, A torque control method in a DC electric dynamometer, characterized in that the field current is controlled by switching field characteristics of the field current control system.