JP2008286580A - Power testing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce torque ripples, which occur in dynamometers, without being restricted by the rotating speed of dynamometers. <P>SOLUTION: A dynamometer 3 is joined to an engine 1 to acquire torque control output at a dynamometer control part 6 on the basis of the deviation between an axial torque command value and an axial torque detection value. The dynamometer is driven by an inverter 7 according to this. A one-control-cyclic-delay circuit 10 acquires torque control output in which torque control output is delayed by one control cycle. A torque ripple compensation circuit 11 computes torque ripples of a frequency to be compensated for of an integral multiple of the rotational number of the dynamometer on the basis of the torque control output of the one-control-cyclic-delay circuit, feeds back the torque ripples to the torque control output, and reduces the torque ripples of the frequency to be compensated for among torque ripples which have occurred in the dynamometer. A specific frequency signal generating part (nth) 12 generates a frequency of an integral multiple (order) of the rotational number of the dynamometer 3 detected by a pulse pickup 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power test system in which a dynamometer is coupled to a specimen such as an engine, a drive system, or a vehicle to perform a power test on the specimen, and in particular, a dynamometer control for suppressing torque ripple generated in the dynamometer. It relates to the device.

  FIG. 15 shows a schematic configuration of a dynamometer control system (see, for example, Patent Document 1). This figure shows the case of an engine power test system, in which a dynamometer 3 is connected to an output shaft of the engine 1 by a coupling shaft 2, and output control of the engine 1 is performed by an engine control unit 4 and a throttle actuator 5, and dynamo control is performed. The shaft torque of the dynamometer 3 is controlled by the unit 6 and the inverter 7 as a power converter.

  In controlling the dynamometer 3, the deviation between the shaft torque command value and the detected value is set to a dynamometer so that the torque value detected by the shaft torque meter 8 installed between the engine 1 and the dynamometer 3 becomes a desired value. The deviation proportional integral (PI) calculation result as an input of the control unit 6 is set as a torque current command value of the inverter 7. Furthermore, when speed control of the engine 1 is performed, feedback control is performed with a speed detection value obtained by a pulse pickup (speed detector) 9.

Patent Document 1 also proposes a design method based on the μ design method for the dynamo control unit 6.
JP 2003-149085 A

  In general, due to the characteristics of the dynamometer and the characteristics of the inverter, the torque output from the dynamometer does not follow the torque current command value given to the inverter, and a torque ripple synchronized with the rotation of the dynamometer occurs. In the conventional dynamometer control method, the resonance is not expanded even if the torque ripple frequency matches the resonance frequency of the engine-dynamometer.

  However, the conventional dynamometer control methods mainly focus on suppressing resonance and suppressing disturbance torque in the low frequency range (dynamometer torque ripple and torque generated by the engine). It is not intended to be suppressed.

  FIG. 16 shows a gain diagram from dynamometer torque ripple to shaft torque in the engine test system shown in FIG. As shown in the figure, it can be seen that the gain is 0 dB or less in the region where the frequency (the number of revolutions) is low, and it operates to suppress the dynamometer torque ripple, but it is about 50 Hz to 200 Hz. It can be seen that the gain exceeds 0 dB in the high rotational speed region, and the torque ripple generated in the dynamometer expands (amplifies). The gain diagram shown in FIG. 16 exhibits the same phenomenon in a drive system and a vehicle test system.

  Depending on the content of the test, the magnifying torque ripple may adversely affect the engine and the drive system as a specimen (deterioration of test accuracy, generation of mechanical fatigue due to vibration) depending on the test contents.

  An object of the present invention is to provide a power test system capable of suppressing torque ripple generated in a dynamometer without being limited by the rotational speed of the dynamometer.

(Principle of the present invention)
FIG. 17 is a transfer function block for explaining the present invention in principle, and a torque ripple compensation circuit and one control are added to a control system constituted by a dynamo control unit 6, an inverter 7 and a dynamometer 3 corresponding to FIG. 15. A cycle delay circuit is added. Among these, Gp represents a transfer function of the dynamometer 3, Ga represents a transfer function of the inverter 7, and Gc represents a transfer function of the dynamo control unit 6. G represents the transfer function of the torque ripple compensation circuit, and Gz represents the transfer function of the one control cycle delay circuit. Regarding the signal, d indicates a dynamometer torque ripple, y indicates a detected shaft torque value, and r indicates a shaft torque command value. When the transfer function from [r, d] to y in this figure is obtained, the following relational expression is obtained.

  At this time, if the transfer function G of the torque ripple compensation circuit is designed so that G · Gz = 1, y = r, and the dynamometer torque ripple d does not appear in the detected shaft torque value y.

  In general, since Gz has a delay element, it is impossible to design a transfer function G of a torque ripple compensation circuit in which G · Gz = 1 for an arbitrary frequency.

  The present invention pays attention to the fact that the frequency of the dynamometer torque ripple is synchronized with an integral multiple of the dynamometer angular velocity, and a torque ripple compensation circuit having a transfer function G such that G · Gz = 1 for only a specific frequency. By providing, it solves the above-mentioned problems and is characterized by the following configuration.

(Structure of the invention)
(1) A dynamometer is connected to the specimen, and the dynamometer torque control output is output to the dynamo control unit based on the deviation between the dynamometer shaft torque command value or the dynamometer torque command value and the shaft torque detection value of the dynamometer. In a power test system including a dynamometer control device that obtains a drive output of a dynamometer in a power converter according to the torque control output,
The dynamometer control device includes:
A control cycle delay circuit for obtaining a torque control output obtained by delaying the torque control output of the dynamo control unit by one control cycle;
From the torque control output of the one control cycle delay circuit, the torque ripple of the compensation target frequency that is an integral multiple of the rotational speed of the dynamometer is calculated, and this torque ripple is fed back to the torque control output of the dynamo control unit to A torque ripple compensation circuit that suppresses torque ripple of the frequency to be compensated among torque ripples generated in the meter is provided.

  (2) The torque ripple compensation circuit is characterized in that a plurality of torque ripples are calculated for each frequency to be compensated and the torque ripple is suppressed for each frequency to be compensated.

  (3) The torque ripple compensation circuit sin-converts and cos-converts the output of the one control cycle delay circuit at the specific frequency (f), and passes the converted signals to a low-pass filter (LPF), respectively. As a result, only the sin component and the cos component of the frequency (f) included in the torque output of the dynamometer are extracted, and these are subjected to inverse sin conversion at the specific frequency (f) obtained by correcting the phase delay of the one control cycle delay circuit. And an arithmetic block configuration that obtains a torque ripple waveform of a specific frequency (f) component included in the torque output of the dynamometer by synthesizing by inverse cos conversion and correcting with the gain of the one control cycle delay circuit. Features.

  As described above, according to the present invention, it becomes possible to increase the effect of suppressing dynamometer torque ripple, which was difficult with the conventional control method, and a highly accurate load torque can be applied to the engine and the drive system device to be tested. The given power test becomes possible.

(Embodiment 1)
FIG. 1 is a control circuit diagram of a dynamometer according to this embodiment. 15 differs from FIG. 15 in that a control cycle delay circuit (1 / z) 10 of the torque ripple compensation circuit and a positive feedback circuit of the torque ripple compensation circuit 11 are provided between the dynamo control unit 6 and the inverter 7. It is in the point. The specific frequency signal generation unit (nth) 12 is set with the rotation speed of the dynamometer 3 detected by the pulse pickup 9 as a fundamental frequency, and an integer multiple (order) frequency is set as a torque ripple compensation target frequency. Generate double frequency signal.

  These circuits 10 and 11 are designed to have the transfer functions Gz and G in FIG. 17, and the torque ripple compensation circuit 11 has G · Gz = 1 for only a specific frequency (an integer multiple of the rotational speed of the dynamometer). By having the transfer function G, torque ripple at a specific frequency is suppressed.

  For this purpose, the torque ripple compensation circuit 11 calculates a torque ripple (amplitude and phase) of a specific frequency contained in the torque control output (inverter current command) of the dynamo control unit 6 and compensates it for the torque control output. Is added to suppress torque ripple.

  FIG. 2 shows a calculation block of the torque ripple compensation circuit 11. In the figure, the torque detected by the one control cycle delay circuit 10 is input as “TrqRef”, and the output frequency f (nth) of the specific frequency signal generation unit 12 in which the order of the compensation target torque ripple is set is the torque ripple compensation target. Input as frequency “Vel”. For example, when the torque ripple to be compensated has a frequency four times the dynamometer rotation speed, nth = 4. The “CmpTrq” output is an output signal of the torque ripple compensation circuit 11.

  Each arithmetic block in FIG. 2 performs sin conversion and cos conversion on the torque output “TrqRef” of the control cycle delay circuit 10 at a specific frequency, and passes the converted signals through the low-pass filter LPF, thereby generating a torque output “ Extract only the sine component and cosine component of the specific frequency included in “TrqRef”, and correct the phase lag and gain based on the torque-phase characteristics of the one control cycle delay circuit 10 when performing inverse sine conversion and inverse cos conversion. Thus, the torque ripple compensation amount “CmpTrq” of the specific frequency is obtained.

  The principle that the torque ripple compensation can be calculated will be described. First, a certain signal waveform x (t) is developed as a Fourier series and can be expressed by the following equation (2).

  Here, in order to extract the secondary component (sin2nt) from the signal waveform x (t), when both sides of the equation (2) are multiplied by sin2nt, the equation (3) is obtained.

When low-pass filter processing with an appropriate order and cutoff frequency is performed on each component on the right side of Equation (3), the high frequency component is deleted and only the term having b ₂ · sin ² 2nt is extracted. Can do. In other words, by expanding the b ^₂ · sin ₂ 2nt components, results in Equation (4), can be low-pass filtering, to obtain only the constant term of b _2/2.

For this constant term b _2/2, by performing the inverse sin transformation and gain correction of equation (5), can be obtained the waveform of Sin2nt.

Similarly, multiplying the Cos2nt to both sides of the equation (2) for extraction of the secondary component (Cos2nt), can only be obtained constant term of a _2/2 by which the low-pass filtering, the formula (5 ) To obtain a cos2nt waveform, and by combining this with a sin2nt component, a secondary (2n) frequency component included in the signal x (t) can be calculated.

  The torque ripple compensation circuit 11 is composed of elements necessary for the above calculation. First, the signal at the compensation target frequency f is integrated by the integrator 21 to obtain the phase θ, and the sin function calculator 22 obtains a sin (f) component for this signal. Similarly, a cos function calculator 23 obtains a cos (f) component for the signal of frequency f.

  Next, in the multipliers 24 and 25, sin (f) from the function calculators 22 and 23 is applied to the torque control signal (corresponding to x (t) in the above equation 2) detected by the one control cycle delay circuit 10. The sin and cos transforms are performed by multiplying the component and the cos (f) component, and the coefficients a / 2, b / of only the sin (f) component and the cos (f) component are passed through the low-pass filters 26 and 27 from these signals. 2 is extracted.

  Next, the multiplier 28 multiplies the coefficient b / 2 by the sin (f) waveform to obtain a sin (f) waveform having the coefficient b / 2. Similarly, the multiplier 29 multiplies the coefficient a / 2 by the cos (f) waveform to obtain a cos (f) waveform having the coefficient a / 2. These are the above inverse sin transform and inverse cos transform.

  Next, the adder 30 obtains a waveform of the frequency f by calculation of (a / 2 · cos (f) + b / 2 · sin (f)). The multiplier 31 multiplies the sin (f) waveform having the coefficient b / 2 and the cos (f) waveform having the coefficient a / 2 by the coefficient “2” to obtain the sin (f) component having the coefficient b and the coefficient a. A waveform having a frequency f that becomes a cos (f) component is obtained. The multiplier 32 multiplies the waveform of the frequency f component by a gain to correct the gain, and obtains this as a torque ripple compensation output of the frequency f component.

  Here, the phase lag and gain of the one control cycle delay circuit 10 are corrected in the calculated value for torque ripple compensation. In this correcting means, the phase delay setting device 33 is preset with phase characteristic data (for example, the data shown in FIG. 3) of the one control cycle delay circuit 10, and among these data, the phase delay data at the frequency f is stored. generate. Further, the gain setting unit 34 is preset with gain characteristic data (for example, data shown in FIG. 4) of the one control cycle delay circuit 10, and the data corresponding to the gain at the frequency f is generated.

  Of these, gain data is corrected by giving the gain data to the multiplier 32 as a coefficient. The phase delay data is supplied to the subtractors 35 and 36 as a phase shift to correct the phase of the frequency f, and the phase-corrected frequency f signal is input to the sin function calculator 37 and the cos function calculator 38. Thus, waveforms for inverse sin conversion and inverse cos conversion in the multipliers 28 and 29 are obtained.

  The result of having performed simulation in order to verify the torque ripple suppression effect by this embodiment is demonstrated below.

  FIG. 5 shows the shaft torque command value and shaft when the dynamo control unit 6 and the torque ripple compensation circuit 11 are omitted and the shaft torque command value is directly input as the torque current command value of the inverter 7 in the control circuit configuration of FIG. It is a response waveform of a torque detection value. Here, the dynamometer torque ripple simulates the fourth and 48th orders of the dynamometer rotation speed. In this calculation, the 48th-order torque ripple resonates over time because the engine controls the dynamometer speed so that the 48th-order frequency of the dynamometer speed matches the resonance frequency of the test equipment mechanical system. As a result, the shaft torque detection value and the shaft torque command value are completely different.

  FIG. 6 is a response waveform when only the dynamo control unit 6 having a resonance suppression effect is provided in the control circuit configuration of FIG. In this case, since the resonance is suppressed, the shaft torque detection value and the shaft torque command value are close to each other as compared with FIG. 5, but the 48th-order component still appears greatly. The undulation waveform in FIG. 6 is a fourth-order component, and the 48th-order component has a high frequency, so that it is filled in the figure.

  FIG. 7 is a response waveform when nth = 48 is set and 48th-order component torque ripple compensation is performed in the control circuit configuration of FIG. Compared to FIG. 6, it can be seen that the fourth-order component (swell waveform) remains, but the 48th-order component (filled high-frequency waveform in FIG. 6) is suppressed over time.

(Embodiment 2)
FIG. 8 is a control circuit diagram of the dynamometer according to the present embodiment. The present embodiment is a case where compensation is performed with two orders as the to-be-compensated torcuril. In FIG. 8, the specific frequency signal generation units 12A and 12B generate frequencies of two compensation target torque ripple orders. The torque ripple compensation circuits 11A and 11B have the same configuration as the torque ripple compensation circuit 11 of the first embodiment, and obtain torque ripple compensation outputs for two specific frequencies having different orders. These torque ripple compensation outputs are added by the adder 13 and added to the output of the dynamo control unit 6 to obtain torque ripple compensation for two specific frequencies.

  In addition, when the three or more orders are torque ripples to be compensated, the torque ripple compensation circuit 11 and the specific frequency signal generation unit 12 for designating the compensation order are added in the same manner, and the total output value of each torque ripple compensation circuit May be added to the output of the dynamo controller.

  Also in this embodiment, a simulation was performed to verify the torque ripple suppression effect.

  FIG. 9 shows a case where torque ripple compensation is performed under the same conditions as the simulation conditions based on the first embodiment and nth1 = 4 and nth2 = 48 so as to suppress both the fourth-order component and the 48th-order component. In FIG. 7, the quaternary component remains, but in FIG. 9, the quaternary component is also suppressed, and it can be seen that the detected shaft torque has a waveform very close to the shaft torque command value.

(Embodiment 3)
FIG. 10 is a control circuit diagram of the dynamometer according to the present embodiment. 1 is different from FIG. 1 in that a value obtained through a feedback gain adjustment block 14 that multiplies a desired dynamometer torque command value by a very small gain K of about K = 0.1 to a shaft torque detection value is fed back. This is a case where torque ripple compensation is performed by the torque ripple compensation circuit 11 for the torque control system.

  Also in this embodiment, a simulation was performed to verify the torque ripple suppression effect.

  11 omits the feedback gain adjustment block 14 and the torque ripple compensation circuit 11 in the configuration of FIG. 10, and the dynamometer torque command value and the power when the dynamometer torque command value is directly input as the torque current command value of the inverter 7. The response waveform of the total torque is shown. Here, the dynamometer torque ripple simulates the cases of the 4th order and the 24th order of the dynamometer rotation speed. Due to the torque ripple, the dynamometer torque has a waveform that is significantly different from the command value.

  FIG. 12 is a response waveform when the order nth = 4 of the specific frequency signal generation unit 12 is set in the configuration of FIG. 10 and torque ripple compensation of a fourth-order component is applied. Compared with FIG. 11, it can be seen that the 24th order component remains, but the 4th order component is suppressed, and the dynamometer torque approaches the command value.

(Embodiment 4)
FIG. 13 is a control circuit diagram of the dynamometer according to the present embodiment. As in the relationship between the first and second embodiments, the present embodiment is a case where the frequency of the compensation target torque ripple is set to two orders in the configuration of the third embodiment.

  Note that FIG. 13 shows the case where there are two orders to be compensated. However, when there are three or more orders, the torque ripple compensation circuit 11 and the specific frequency signal generator 12 are added for each order as in the second embodiment. These may be added by the adder 13.

  Also in this embodiment, a simulation was performed to verify the torque ripple suppression effect.

  FIG. 14 shows a case where a torque ripple compensation circuit is provided to suppress both the fourth-order component and the 24th-order component under the same conditions as in the third embodiment, with nth1 = 4 and nth2 = 24. Although the 24th order component remains in FIG. 12, the 24th order component is also suppressed in FIG. 14, and it can be seen that the dynamometer torque has a waveform very close to the dynamometer torque command value.

  The first to fourth embodiments described above show the case where the present invention is applied to an engine power test system, but the same effects can be obtained by applying the present invention to a drive system and a vehicle power test system.

The control circuit diagram of the dynamometer which shows Embodiment 1 of this invention. The operation block diagram of the torque ripple compensation circuit in an embodiment. The phase characteristic data example of 1 control period delay circuit in embodiment. The gain characteristic data example of 1 control period delay circuit in embodiment. The example of a simulation waveform of a shaft torque command value and a shaft torque detection value when a shaft torque command value is an inverter current command value. The example of a simulation waveform of a shaft torque command value and a shaft torque detection value when only a dynamo control unit is provided. Simulation waveform example of shaft torque command value and shaft torque detection value when a torque ripple compensation circuit is provided. The control circuit diagram of the dynamometer which shows Embodiment 2 of this invention. Simulation waveform example in which the 4th and 48th components are compensated. The control circuit diagram of the dynamometer which shows Embodiment 3 of this invention. The example of a simulation waveform of a shaft torque command value and a shaft torque detection value when a shaft torque command value is an inverter current command value. Simulation waveform example in which the 4th and 48th components are compensated. The control circuit diagram of the dynamometer which shows Embodiment 4 of this invention. Simulation waveform example in which fourth and 24th order components are compensated. The block diagram of the conventional engine test system. The example of the gain diagram from the conventional dynamometer torque ripple to shaft torque. The transfer function block diagram for demonstrating this invention in principle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Coupling shaft 3 Dynamometer 4 Engine control part 5 Throttle actuator 6 Dynamo control part 7 Inverter 8 Torque meter 9 Pulse pickup 10 1 Control period delay circuit 11, 11A, 11B Torque ripple compensation circuit 12, 12A, 12B Specific frequency generation Part 13 Adding part 14 Feedback gain adjustment block

Claims (3)

A dynamometer is coupled to the specimen, and a dynamometer torque control output is obtained in the dynamo control unit based on the deviation between the dynamometer shaft torque command value or the dynamometer torque command value and the dynamometer shaft torque detection value, In a power test system including a dynamometer control device that obtains a drive output of a dynamometer in a power converter according to the torque control output,
The dynamometer control device includes:
A control cycle delay circuit for obtaining a torque control output obtained by delaying the torque control output of the dynamo control unit by one control cycle;
From the torque control output of the one control cycle delay circuit, the torque ripple of the compensation target frequency that is an integral multiple of the rotational speed of the dynamometer is calculated, and this torque ripple is fed back to the torque control output of the dynamo control unit to A power test system comprising: a torque ripple compensation circuit that suppresses torque ripple of the frequency to be compensated among torque ripples generated in a meter.   2. The power test system according to claim 1, wherein the torque ripple compensation circuit is configured to calculate a plurality of torque ripples for each frequency to be compensated and to suppress the torque ripple for each frequency to be compensated.   The torque ripple compensation circuit performs sin conversion and cos conversion on the output of the one control cycle delay circuit at the specific frequency (f), and passes these converted signals through a low-pass filter (LPF), respectively. Only the sine component and the cosine component of the frequency (f) included in the torque output of the dynamometer are extracted, and these are converted to the inverse sin conversion and inverse cos at the specific frequency (f) obtained by correcting the phase delay of the one control cycle delay circuit, respectively. An arithmetic block configuration is obtained in which a torque ripple waveform of a specific frequency (f) component included in the torque output of the dynamometer is obtained by converting and synthesizing and correcting with the gain of the one control cycle delay circuit. The power test system according to claim 1 or 2.

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