Characteristic testing method for motor under test, characteristic testing device, and computer program

Abstract

To provide a technique for obtaining apparent power and power factor while eliminating the influence of induced voltage.SOLUTION: A method includes (a) a step for acquiring voltage measurement values Es[j] and current measurement values Is[j] by measuring the coil voltage and coil current of the motor under test at M measurement timings, respectively, (b) a step for determining that an effective voltage value Er[j] is equal to the voltage measurement value Es[j] when a current indicator value, which increases or decreases according to the current measurement value Is[j], is equal to or greater than a predetermined determination value, (c) a step for determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero by assuming that there is an influence of induced voltage when the current indicator value is below the determination value for Lmax or more consecutive measurement timing points, and (d) a step for calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at M measurement timings.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for testing the characteristics of a motor under test, a characteristic testing device, and a computer program. [Background technology]

[0002] Patent Document 1 describes a synchronous motor drive device capable of calculating the power factor of a synchronous motor. Generally, the power factor is calculated by dividing the active power by the apparent power. Furthermore, the power factor decreases when there is a phase lag in the current. Therefore, so-called lead angle control has traditionally been employed to eliminate the phase difference between the voltage and current. However, lead angle control alone cannot bring the power factor sufficiently close to 1.0, and this has been thought to be entirely due to harmonic loss. Therefore, measures have been required for the motor drive control circuit to suppress this harmonic loss, but until now, it has been impossible to improve the power factor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2013-201805 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present disclosure discovered that an induced voltage occurs in a motor's electromagnetic coil during its non-excitation period, and that this induced voltage increases the effective voltage value. When the effective voltage value increases due to the induced voltage, the apparent power also increases, resulting in a decrease in the power factor. It was therefore discovered that conventional techniques have been unable to accurately measure the motor's inherent apparent power and power factor. Therefore, there is a need for a technology that can eliminate the influence of the induced voltage and accurately measure the motor's inherent apparent power and power factor. There is also a need for a technology that can reduce harmonic loss in a drive device that uses a motor. [Means for solving the problem]

[0005] The present disclosure has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0006] According to a first aspect of the present disclosure, there is provided a method for testing characteristics of a motor under test, which includes the steps of: (a) measuring a coil voltage and a coil current of the motor under test at M measurement timings spanning N periods of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number ranging from 1 to M, to obtain a voltage measurement value Es[j] and a current measurement value Is[j] at the jth measurement timing; and (b) determining whether an effective voltage value Er[j] at the jth measurement timing is greater than or equal to the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value. (c) determining an induced voltage influence period by assuming that the influence of an induced voltage is occurring when the measurement timings at which the current index value is less than the judgment value occur Lmax or more times, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This method eliminates the influence of induced voltage and allows accurate calculation of apparent power and power factor. Furthermore, if the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more times, it is assumed that the influence of induced voltage is occurring, and the induced voltage influence period is determined accordingly. Therefore, the harmonic generation period and the induced voltage influence period can be distinguished so that they do not overlap, allowing for accurate evaluation of harmonic loss.

[0007] A second aspect of the present disclosure provides a characteristic test apparatus for testing the characteristics of a motor under test. The characteristic test apparatus includes a measurement acquisition unit that acquires a voltage measurement value Es[j] and a current measurement value Is[j] at the jth measurement timing by measuring the coil voltage and coil current of the motor under test at M measurement timings spanning N periods of the coil voltage, where N is an integer greater than or equal to 1, M is an integer greater than N, and j is an ordinal number from 1 to M, and a characteristic calculation unit that calculates the characteristics of the motor under test using the voltage measurement value Es[j] and the current measurement value Is[j]. The characteristic calculation unit is configured to execute the following processes: determining that the effective voltage value Er[j] at the jth measurement timing is equal to the voltage measurement value Es[j] when a current index value, which increases or decreases according to the current measurement value Is[j], is equal to or greater than a predetermined judgment value; determining an induced voltage influence period by assuming that an induced voltage influence is occurring when the measurement timings at which the current index value is less than the judgment value occur Lmax or more times, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This characteristic test device can calculate accurate apparent power and power factor by eliminating the influence of induced voltage. Furthermore, if the measurement timing at which the current index value is less than the judgment value occurs Lmax times or more in succession, it is assumed that the influence of induced voltage is occurring and the induced voltage influence period is determined. Therefore, it is possible to distinguish between the harmonic generation period and the induced voltage influence period so that they do not overlap, and harmonic loss can be correctly evaluated.

[0008] According to a third aspect of the present disclosure, there is provided a computer program for executing a process of testing characteristics of a motor under test. This computer program includes: (a) a process of measuring a coil voltage and a coil current of the motor under test at M measurement timings over a period of N coil voltage periods, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number from 1 to M, thereby obtaining a voltage measurement value Es[j] and a current measurement value Is[j] at the jth measurement timing; and (b) a process of determining whether an effective voltage value Er[j] at the jth measurement timing is equal to or greater than the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value. (c) determining that the effective voltage value Er[j] is equal to zero when the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more, where Lmax is an integer equal to or greater than 2; determining an induced voltage influence period by assuming that the influence of induced voltage is occurring and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This computer program can accurately calculate apparent power and power factor by eliminating the influence of induced voltage. Furthermore, if the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more times, it is assumed that the influence of induced voltage is occurring, and the period affected by induced voltage is determined accordingly. Therefore, it is possible to distinguish between the harmonic generation period and the induced voltage influence period so that they do not overlap, enabling accurate evaluation of harmonic loss.

[0009] According to a fourth aspect of the present disclosure, there is provided a drive device including a PWM drive circuit and a motor, the drive device further including a harmonic filter disposed between the PWM drive circuit and the motor, the harmonic filter being configured such that the wiring length between the motor and the harmonic filter is shorter than the wiring length between the PWM drive circuit and the harmonic filter. This driving device can reduce harmonic losses during PWM driving. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a configuration of a motor testing system according to an embodiment. [Figure 2] Graphs showing the drive waveform of the motor under test and the measured voltage and current values. [Figure 3] FIG. 4 is a diagram showing an operating state of a drive circuit. [Figure 4] 4 is a flowchart showing the procedure for testing the characteristics of a motor under test. [Figure 5] 10 is a flowchart showing the procedure of non-zero current value processing in step S30. [Figure 6] 10 is a flowchart showing the procedure of zero current value processing in step S40. [Figure 7] FIG. 10 is an explanatory diagram showing an example of a first display screen of the characteristics of the motor under test. [Figure 8] FIG. 10 is an explanatory diagram showing an example of a second display screen of the characteristics of the motor under test. [Figure 9] FIG. 10 is an explanatory diagram showing the configuration of a drive device in a comparative example. [Figure 10] FIG. 2 is an explanatory diagram showing the configuration of a drive device in the first embodiment. [Figure 11] FIG. 10 is an explanatory diagram showing the configuration of a drive device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1 is a block diagram showing the configuration of a motor testing system according to an embodiment. The motor testing system includes a motor under test 100, a motor testing device 200, and a characteristic testing device 300.

[0012] Any type of motor with any number of phases can be used as the motor under test 100. However, the motor under test 100 uses a permanent magnet rotor that uses a ferromagnetic neodymium magnet, which generates an induced voltage, and the phenomenon that is the subject of this disclosure is particularly noticeable in high-torque motors with small phase coil inductance (small number of turns).

[0013] The motor under test 100 is electrically connected to a drive circuit 120. A DC input voltage Ev is supplied to the drive circuit 120 from a constant-voltage power supply 130. The voltage value of the input voltage Ev can be adjusted by a characteristic test device 300. The drive circuit 120 is a motor driver configured, for example, as an H-bridge circuit. Transistors in the drive circuit 120 are turned on / off in response to a control signal Sd supplied from the characteristic test device 300. The control signal Sd is, for example, a signal for PWM control of the motor under test 100. In PWM control, the rotational position of the motor under test 100 is detected based on the output of the magnetic sensor 104, and a control signal Sd for each phase is generated based on this rotational position. An ammeter 151 for measuring the coil current of the electromagnetic coil and a voltmeter 161 for measuring the coil voltage of the electromagnetic coil are provided in the wiring between the drive circuit 120 and the motor under test 100.

[0014] The motor testing device 200 includes a first coupling 211, a torque meter 220, a second coupling 212, an electric brake 230, an AC / DC conversion unit 240, a DC load unit 250, and a measurement value collection unit 260. The mechanical connection structure including the first coupling 211, the torque meter 220, the second coupling 212, and the electric brake 230 is referred to as a test connection structure 270.

[0015] The rotating shaft 110 of the motor under test 100 and the first rotating shaft 221 of the torque meter 220 are connected by a first coupling 211. The torque meter 220 has a first rotating shaft 221 and a second rotating shaft 222 and measures the torque T between the first rotating shaft 221 and the second rotating shaft 222. The torque meter 220 is preferably configured to further measure the rotation speed Nm of the rotating shafts 221 and 222. Instead of measuring the rotation speed Nm with the torque meter 220, the rotation speed Nm may be measured with high accuracy based on a clock counter value in a sensor signal using a magnetic sensor 104 provided in the motor under test 100. The second rotating shaft 222 of the torque meter 220 and the rotating shaft 232 of the electric brake 230 are connected by a second coupling 212. The electric brake 230 has a coreless motor structure with low iron loss (cogging loss, hysteresis loss, etc.). The electric brake 230 is preferably configured as, for example, a two-phase or three-phase brushless motor. In this embodiment, the electric brake 230 has a magnetic sensor 234 that measures the rotational position of the rotor. In this embodiment, the magnetic sensor 234 is a sensor that is fixed to the stator and measures the magnetic flux density of a permanent magnet provided in the rotor. The magnetic sensor 234 is configured, for example, by a Hall IC. However, the magnetic sensor 234 can be omitted.

[0016] AC / DC conversion unit 240 is electrically connected to the multi-phase coils of electric brake 230, and converts AC induced voltage Vi generated in the coils into DC voltage Vd by full-wave rectification. DC load unit 250 is electrically connected to AC / DC conversion unit 240, and consumes power generated by DC voltage Vd.

[0017] The measurement value collection unit 260 collects the measurement value Es of the coil voltage measured by the voltmeter 161, the measurement value Is of the coil current measured by the ammeter 151, and the torque T and rotation speed Nm measured by the torque meter 220 in synchronization with the control signal Sd of the drive circuit 120, and transfers them to the characteristic test device 300.

[0018] The characteristic test apparatus 300 includes a measurement value acquisition unit 310, a characteristic calculation unit 320, and a characteristic display unit 330. The characteristic test apparatus 300 also has the function of controlling each unit of the motor testing apparatus 200. The measurement value acquisition unit 310 acquires measurement values, including the coil voltage and coil current measurement values ​​Es and Is, of the motor under test 100 from the measurement value collection unit 260. The characteristic calculation unit 320 calculates the characteristics of the motor under test 100 using the coil voltage and coil current measurement values ​​Es and Is. The characteristic display unit 330 displays the calculated characteristics of the motor under test 100 on a display screen. In this embodiment, the characteristic calculation unit 320 calculates the apparent power and power factor of the motor under test 100. The characteristic test apparatus 300 can be implemented, for example, by a personal computer. The functions of the characteristic test apparatus 300 are implemented by a processor executing a computer program stored in the memory of the characteristic test apparatus 300.

[0019] FIG. 2 is a graph showing the drive waveform, voltage measurement value Es[j], and current measurement value Is[j] of the motor under test 100. In this embodiment, the motor under test 100 is a two-phase brushless motor that is PWM-controlled. The A-phase voltage Va and B-phase voltage Vb shown at the top of FIG. 2 represent ideal analog voltage waveforms of the two-phase electromagnetic coils. The voltage waveforms of the A-phase voltage Va and B-phase voltage Vb change periodically every Pw. One Pw period corresponds to 360 electrical degrees. The PWM-controlled A-phase voltage Vapwm is a rectangular wave, as shown in the third graph from the top of FIG. 2. The A-phase voltage Vapwm shown in the fourth graph from the top of FIG. 2 is an enlarged view of a portion. The dashed-dotted line indicates measurement timing j, i.e., sampling timing.

[0020] The second and third graphs from the bottom in Figure 2 show enlarged voltage measurement values ​​Es[j] and current measurement values ​​Is[j] measured during one period Pe of the PWM controlled square wave. The voltage measurement values ​​Es[j] and current measurement values ​​Is[j] are values ​​measured at measurement timing j, indicated by the dashed dotted line.

[0021] One cycle Pe of the PWM control square wave can be divided into three periods P1 to P3. The first period P1 is the PWM drive period of the coil, that is, the ON period of PWM control during which the coil current increases. During this first period P1, the measured voltage value Es[j] is a positive value, the measured current value Is[j] gradually increases, and electrical energy is stored in the A-phase coil. The second period P2 is the coil discharge period, during the OFF period of PWM control during which the coil current decreases. During this second period P2, the measured voltage value Es[j] is a negative value, the measured current value Is[j] gradually decreases, and the electrical energy stored in the A-phase coil is released.

[0022] The third period P3 is the period after the absolute value of the measured current Is[j] decreases and reaches zero during the PWM control off period, and before PWM control returns to the first period P1. This third period P3 is divided into a harmonic generation period P31, during which harmonic losses occur, and an induced voltage influence period P32, during which the induced voltage Ed generated in the electromagnetic coil as the rotor rotates is detected. During the induced voltage influence period P32, the induced voltage Ed appears according to the rotor rotation speed, so the measured voltage Es[j] is non-zero and the measured current Is[j] is approximately zero. The waveform of the induced voltage Ed has a sinusoidal shape that changes depending on the relative positions of the electromagnetic coil and the permanent magnet. The change in induced voltage Ed between the first period P1 and the second period P2 is depicted by the dotted line. In this way, an induced voltage Ed is generated in response to the rotation of the rotor in the first period P1 and the second period P2, but the drive voltage is larger than the induced voltage Ed, and a coil current is generated due to the potential difference between them (drive voltage - induced voltage Ed).Since the induced voltage Ed is hidden by this potential difference, the induced voltage Ed cannot be clearly recognized in the first period P1 or the second period P2.

[0023] The zero current value detection flag Fz is shown at the bottom of FIG. 2. The zero current value detection flag Fz is a flag that changes from 0 (FALSE) to 1 (TRUE) when an induced voltage is detected. The zero current value detection flag Fz changes from 0 to 1 when the number of consecutive measurement times at which the current index value, which increases or decreases according to the current measurement value Is[j], is less than a predetermined judgment value is Lmax or more, where Lmax is an integer greater than or equal to 2. In the example of FIG. 2, Lmax=3, and the zero current value detection flag Fz is set when the absolute value of the current measurement value Is[j] is less than the judgment value three consecutive times. The induced voltage influence period P32 is determined from the time when the zero current value detection flag Fz is set. Specifically, when the zero current value detection flag Fz is set, it is determined that the induced voltage influence period P32 has started, going back to the (Lmax-1) measurement time before. These processes will be described in detail later.

[0024] FIG. 3 shows the operating states of the drive circuit 120 during the three periods P1 to P3 in FIG. 2. The drive circuit 120 includes an H-bridge circuit consisting of four transistors Qt1, Qb1, Qt2, and Qb2 that drive the A-phase coil 101. Control signals St1, Sb1, St2, and Sb2 are input to the gate electrodes of the four transistors Qt1, Qb1, Qt2, and Qb2, respectively. When the A-phase coil 101 is driven during the first period P1, two transistors Qb1 and Qt2 are turned on, and the other two transistors Qt1 and Qb2 are turned off. In this state, current flows through the A-phase coil 101 through a path including the two transistors Qb1 and Qt2, as indicated by the dashed line. The voltage level of the rectangular pulse voltage is approximately the same as the input voltage Ev supplied from the constant-voltage power supply 130.

[0025] During the second period P2, transistor Qt2 is switched from on to off. In this state, as shown by the dashed line, current flows to the A-phase coil 101 through a path that includes the flywheel diode of transistor Qt2 and transistor Qb1. Note that while the example in FIG. 3 shows a discharge period on the low side, which is the ground side, a similar discharge period can also be set on the high side, which is the power supply side.

[0026] During the third period P3, the on / off states of transistors Qt1, Qb1, Qt2, and Qb2 are the same as during the second period P2. In this state, discharge from the A-phase coil 101 ends, and an induced voltage Ed due to rotor rotation is generated in the A-phase coil 101. As described in FIG. 2, during the harmonic generation period P31 that appears in the first half of the third period P3, currents associated with harmonics are generated, resulting in copper loss. Furthermore, the phase currents associated with harmonics also generate a braking force that suppresses rotor rotation. During the induced voltage influence period P32 that appears in the second half of the third period, the current is nearly zero.

[0027] The active power P of each phase of the motor under test 100 is calculated as follows using the measured voltage values ​​Es[j] and measured current values ​​Is[j] shown in FIG. P = Km·SQRT{ΣPe[j]^2 / M} …(q1) Pe[j] = Es[j] × Is[j] …(q2) Here, Km is a coefficient determined by the coil structure of the motor under test 100, SQRT{} indicates the square root operation in parentheses, Σ indicates the addition of 1 to M for j, and "^2" indicates the squaring operation. The coefficient Km is a conversion coefficient used to convert line-to-phase power. For an n-phase motor with n being an integer greater than or equal to 2, where each phase has an independent coil, Km is 1.0. For a three-phase motor with a star connection, the phase voltage must be converted to line voltage / √3, and for a delta connection, the phase current must be converted to line current / √3. Therefore, for a star-connected or delta-connected three-phase motor, when calculating the power per phase using line voltage and line current, Km = 1 / √3.

[0028] However, even for a star-connected or delta-connected three-phase motor, when the power for one phase is calculated using the phase voltage and phase current, the coefficient Km in the above equation (q1) is 1.0. Taking this into consideration, when the power for one phase is calculated using the phase voltage and phase current, Km = 1.0 regardless of the coil structure of the motor under test 100. Therefore, in this embodiment, Km = 1.0 is used regardless of the coil structure.

[0029] In this way, the active power P can be calculated by multiplying the voltage measurement value Es[j] by the current measurement value Is[j] to obtain the active power value Pe[j], and then calculating the root mean square SQRT{ΣPe[j]^2 / M} of the active power values ​​Pe[j] obtained at M measurement timings.

[0030] The apparent power Sc of the motor under test 100 is calculated as one phase for each phase as follows: Sc = Km·Es_rms·Is_rms …(q3) Es_rms = SQRT(ΣEs[j]^2 / M) …(q4) Is_rms = SQRT(ΣIs[j]^2 / M) …(q5) In this way, the apparent power Sc can be calculated by multiplying the root mean square Es_rms of the voltage measurement values ​​Es[j] obtained at M measurement timings j by the root mean square Is_rms of the current measurement values ​​Is[j] obtained at M measurement timings j.

[0031] The power factor ηc is calculated by dividing the active power P by the apparent power Sc as follows: ηc = P / Sc …(q6)

[0032] During the induced voltage influence period P32 shown in Figure 2, the induced voltage Ed appears, so the measured voltage Es[j] is not zero and the measured current Is[j] is almost zero. In this case, the active power P given by equations (q1) and (q2) is not affected by the induced voltage Ed during the induced voltage influence period P32 because the measured current Is[j] is almost zero. On the other hand, the apparent power Sc given by equations (q3) to (q5) contains a square component of the measured voltage Es[j], so even if the measured current Is[j] is zero, it increases due to the influence of the induced voltage Ed during the induced voltage influence period P32. Furthermore, when the apparent power Sc increases, the power factor ηc decreases.

[0033] Thus, when the apparent power Sc and power factor ηc are calculated according to the conventional calculation method, the apparent power Sc increases and the power factor ηc decreases due to the influence of the induced voltage Ed during the induced voltage influence period P32. However, since the induced voltage Ed during the induced voltage influence period P32 is unrelated to the drive power, it should be excluded from the calculation of the apparent power and power factor. Therefore, in this embodiment, the induced voltage Ed during the induced voltage influence period P32 is excluded from the effective voltage value used to calculate the apparent power, thereby calculating accurate values ​​of the apparent power and power factor. Furthermore, in this embodiment, the induced voltage influence period P32 is determined using the zero current value detection flag Fz so that the induced voltage influence period P32 does not overlap with the harmonic generation period P31.

[0034] The apparent power Sc and power factor ηc calculated by the above-mentioned equations (q3) to (q6) are values ​​calculated according to conventional calculation methods, and are therefore referred to as "conventional apparent power Sc" and "conventional power factor ηc." The calculation method for apparent power and power factor according to the present disclosure will be described later. On the other hand, the active power P calculated by the above-mentioned equations (q1) and (q2) is not affected by the induced voltage during the induced voltage influence period P32, and is therefore used as is in the calculation method of the present disclosure.

[0035] Conventionally, the reason why the power factor does not become sufficiently high even when advance angle control is performed has been thought to be due to harmonic losses that occur with the square waves of PWM control. However, it is presumed that the main reason why the power factor does not become high with conventional technology is not only the harmonic losses in the harmonic generation period P31, but also the large influence of the induced voltage Ed in the induced voltage influence period P32.

[0036] Furthermore, the third period P3 has not been fully recognized in the past. This is presumably because conventional motors have a cored motor structure and a large number of windings, resulting in high inductance and resistance, preventing the third period P3 from occurring and instead resulting in the first period P1 and the second period P2 being dominant. In recent years, high torque performance has been required of motors for electric motor-based technologies such as electric vehicles, drones, and aircraft. To meet this demand, coreless structures and coil specifications with fewer windings result in significantly lower inductance and resistance, shortening the second period P2 and resulting in the appearance of the third period P3, increasing the importance of the harmonic generation period P31 and the induced voltage influence period P32. This can be considered a new issue that has arisen as motor characteristics have improved in line with the times. This disclosure makes it possible to eliminate the influence of induced voltage during the induced voltage influence period P32 and correctly evaluate harmonic loss during the harmonic generation period P31.

[0037] The present disclosure is not limited to two-phase motors, but can also be applied to three-phase motors. In this embodiment, in the case of a three-phase motor, power and power factor are calculated using phase voltages and phase currents, just as in the case of a two-phase motor. In this disclosure, regardless of the number of phases in the motor, the phase voltage of a coil for one phase is called the "coil voltage." Also, the phase current of a coil for one phase is called the "coil current." Furthermore, the present disclosure is not limited to PWM control, and can also be applied to motors that operate according to control other than PWM control, such as 120-degree conduction control of a three-phase motor.

[0038] In a three-phase motor, the active power Wp of each phase in star connection and delta connection, and the three-phase active power W can be calculated using the following formulas. Wp = 1 / √3 VL I L cosθ …(q7) W = 3 Wp = √3 V L I L cosθ …(q8) where V L is the line voltage and I L is the line current. Line voltage V L and the line current I L When calculating the power using the above formula (q1) and (q3), the coefficient Km in the above formula (q1) and (q3) becomes 1 / √3 on the right side of formula (q7). However, in this embodiment, even in the case of a three-phase motor, the power for one phase is calculated using the phase voltage and phase current, so Km = 1.0.

[0039] 4 is a flowchart showing the procedure for a characteristic test of the motor under test 100. This characteristic test is preferably carried out while the motor under test 100 is rotating at a constant rotation speed Nm and a constant torque T.

[0040] The following parameters are used in the process of Figure 4: ·N: The number of coil voltage periods Pw for measuring the coil voltage and coil current, and is an integer equal to or greater than 1. M: The total number of coil voltage and coil current measurement timings, an integer greater than N. ·j: An ordinal number indicating the measurement timing, an integer from 1 to M. Es[j]: The voltage measurement value of the coil voltage measured at measurement timing j. Is[j]: The current measurement value of the coil current measured at measurement timing j. · Ix[j]: Current index value that increases or decreases according to the current measurement value Is[j]. ·Ixmin: The judgment value of the current index value Ix[j]. ·Er[j]: Effective voltage value. ·Ei[j]: Induced voltage value. ·Fz: Zero current detection flag. L: an integer indicating the number of consecutive measurement timings at which the current index value Ix[j] is less than the judgment value Ixmin. Hereinafter, the parameter L will be referred to as the "number of consecutive zero current values ​​L." · Lmax: Threshold value for the number of consecutive zero current values ​​L. ·S: Apparent power excluding the induced voltage during the induced voltage influence period P32. P: Active power. ·η: Power factor calculated using apparent power S. ·Sc: Conventional apparent power calculated using the conventional calculation method. ·ηc: Conventional power factor calculated using conventional apparent power Sc.

[0041] In step S10, the measurement timing j is set to 1, the number of consecutive zero current values ​​L is set to 1, and the zero current value detection flag Fz is set to 0. The various parameters described above are also initialized. In this embodiment, the number of coil voltage cycles N at which the coil voltage and coil current are measured is set to 1. The threshold value Lmax of the number of consecutive zero current values ​​L is set to 3.

[0042] In step S11, the measurement value acquiring unit 310 acquires the voltage measurement value Es[j] and the current measurement value Is[j] measured at measurement timing j.

[0043] In step S12, the measurement value acquirer 310 calculates a current index value Ix[j] that increases or decreases according to the current measurement value Is[j]. The current index value Ix[j] can be calculated using, for example, either equation (q9) or equation (q10) below. Ix[j] = ABS(Is[j]) …(q9) Ix[j] = ABS(Es[j]·Is[j]) …(q10) Here, ABS() is an operation to take the absolute value in the parentheses.

[0044] The current index value Ix[j] given by the above formula (q9) is the absolute value of the current measurement value Is[j]. The current index value Ix[j] given by the above formula (q10) is the absolute value of the product of the voltage measurement value Es[j] and the current measurement value Is[j], that is, the absolute value of the power measurement value. The current index values Ix[j] given by the formulas (q9) and (q10) are both proportional to the absolute value of the current measurement value Is[j]. However, the current index value Ix[j] may be calculated using a formula other than the formulas (q9) and (q10). In this embodiment, the current index value Ix[j] is calculated using the formula (q9).

[0045] In step S13, the characteristic calculation unit 320 compares the current index value Ix[j] with a preset determination value Ixmin. The determination value Ixmin of the current index value Ix[j] is set to a positive value close to zero, and when the current index value Ix[j] is less than the determination value Ixmin, it is set to a value that can be regarded as the current measurement value Is[j] being substantially zero. When Ixmin ≦ Ix[j], the process proceeds to step S30, and the non-zero current value process is executed. On the other hand, when Ix[j] < Ixmin, the process proceeds to step S40, and the zero current value process is executed.

[0046] FIG. 5 is a flowchart showing the procedure of the non-zero current value process in step S30. In step S31, the continuous number L of zero current values is set to 1, and in step S32, the zero current value detection flag Fz is set to 0. Thus, in the non-zero current value process, the process of returning L and Fz to their initial values is executed. The non-zero current value process in step S30 is a process for returning L and Fz to their initial values when the current index value Ix[j] becomes greater than or equal to the determination value Ixmin at the next measurement timing j + 1 after the measurement timing j when the current index value Ix[j] is less than the determination value Ixmin.

[0047] After step S30 is completed, the process proceeds to step S14, where the effective voltage value Er[j] is determined to be equal to the voltage measurement value Es[j]. The induced voltage value Ei[j] is also determined to be equal to zero. The process of step S14 corresponds to the process of determining the effective voltage value Er[j] from the voltage measurement values ​​Es[j] obtained in the first period P1, the second period P2, and the harmonic generation period P31 shown in FIG. 2. The current measurement value Is[j] is used as the effective current value.

[0048] 6 is a flowchart showing the procedure for the zero current value processing in step S40. In step S41, it is determined whether the zero current value detection flag Fz is 1. If the zero current value detection flag Fz is 1, the induced voltage influence period P32 has already begun before the previous measurement timing, so the processing of step S40 ends and the process proceeds to step S15 in FIG. 4. On the other hand, if the zero current value detection flag Fz is 0, the process proceeds to step S42, where it is determined whether the number of consecutive zero current values ​​L is equal to or greater than a threshold value Lmax.

[0049] If the number of consecutive zero current values ​​L is less than the threshold value Lmax, the number of consecutive zero current values ​​L is incremented by one in step S46, and the process proceeds to step S47, which will be described later. On the other hand, if the number of consecutive zero current values ​​L is equal to or greater than the threshold value Lmax, steps S43 and S44 are executed. In step S43, the zero current value detection flag Fz is set to 1, and in step S44, the parameter Ln is set to Lmax-1. In this embodiment, since Lmax=3, Ln=2.

[0050] In step S45, for the Ln measurement timings [j - Ln]…[j - 1] immediately before the current measurement timing j, it is determined that all the effective voltage values Er[j - Ln]…Er[j - 1] are equal to zero. Also, the induced voltage values Ei[j - Ln]…Ei[j - 1] are determined to be equal to the voltage measurement values Es[j - Ln]…Es[j - 1] respectively. The processing of this step S45 is the processing for correcting the effective voltage value Er and the induced voltage value Ei in the correction period Pc shown in FIG. 2. The correction period Pc is the period immediately after the start of the induced voltage influence period P32, and is the period from the first measurement timing when the current index value Ix[j] becomes less than the determination value Ixmin to the measurement timing immediately before the zero current value detection flag Fz rises to 1. Since the measurement timing when the zero current value detection flag Fz rises to 1 is in the middle of the induced voltage influence period P32, by correcting the effective voltage value Er and the induced voltage value Ei in the correction period Pc in step S45, the effective voltage value Er and the induced voltage value Ei can be correctly determined throughout the induced voltage influence period P32.

[0051] When the correction in step S45 is completed, the process proceeds to step S47, and it is determined whether the zero current value detection flag Fz is equal to 1. Note that when Fz = 0 at the start of step S40 and L < Lmax, steps S43 to S45 are skipped, so Fz = 0 even at the time of step S47. In this case, the processing of step S40 is terminated and the process proceeds to step S14 in FIG. 4. As described above, in step S14, the effective voltage value Er[j] is determined to be equal to the voltage measurement value Es[j], and the induced voltage value Ei[j] is determined to be equal to zero. On the other hand, when Fz = 1 at the time of step S47, the processing of step S40 is terminated and the process proceeds to step S15 in FIG. 4.

[0052] In step S15, the effective voltage value Er[j] is determined to be equal to zero. Also, the induced voltage value Ei[j] is determined to be equal to the voltage measurement value Es[j]. The process of step S15 is a process of determining that the voltage measurement value Es[j] is an induced voltage during the period in which the zero current value detection flag Fz shown in FIG. 2 is 1. The current measurement value Is[j] is used as is as the effective current value.

[0053] In step S16, it is determined whether the measurement timing j has reached the maximum value M. If j is smaller than M, the process proceeds to step S17, where j is incremented by 1, and the process returns to step S11, where the above-described steps S11 to S16 are executed again. If j has reached M, the process proceeds to step S18.

[0054] In step S18, the characteristics calculation unit 320 determines whether to calculate and display the characteristics while excluding the induced voltage. Whether to exclude the induced voltage is specified by the user. If the induced voltage is to be excluded, the process of step S19 is executed, and if the induced voltage is not to be excluded, the process of step S20 is executed.

[0055] In step S19, the characteristics calculation unit 320 uses the effective voltage value Er[j], the measured voltage value Es[j], and the measured current value Is[j] to calculate the active power P, apparent power S, and power factor η of the motor under test 100. The active power P is calculated according to the following equation. P = Km·SQRT{ΣPe[j]^2 / M} …(q11) Pe[j] = Es[j] × Is[j] …(q12) These are the same as the above-mentioned equations (q1) and (q2). That is, the active power P can be calculated by multiplying the measured voltage value Es[j] and the measured current value Is[j] obtained at measurement timing j to obtain the active power value Pe[j], and then calculating the root mean square SQRT{ΣPe[j]^2 / M} of the active power values ​​Pe[j] obtained at M measurement timings.

[0056] The apparent power S is calculated according to the following formula: S = Km·Er_rms·Is_rms …(q13) Er_rms = SQRT(ΣEr[j]^2 / M) …(q14) Is_rms = SQRT(ΣIs[j]^2 / M) …(q15) In this way, the apparent power S can be calculated by multiplying the root mean square Er_rms of the effective voltage values ​​Er[j] obtained at M measurement timings j by the root mean square Is_rms of the current measurement values ​​Is[j] obtained at M measurement timings j.

[0057] The power factor η is calculated by dividing the active power P by the apparent power S as shown in the following equation. η = P / S …(q16)

[0058] In step S20, the characteristic calculation unit 320 calculates the active power P, conventional apparent power Sc, and conventional power factor ηc of the motor under test 100. These characteristics are calculated according to the above-mentioned equations (q1) to (q6).

[0059] In step S21, the characteristic display unit 330 displays the calculated characteristic of the motor under test 100 on the display device of the characteristic test apparatus 300.

[0060] 7 and 8 are explanatory diagrams showing examples of display screens for the characteristics of the motor under test 100. Fig. 7 shows an example of a first display screen W1 that displays the apparent power S and power factor η calculated after eliminating the induced voltage. Fig. 8 shows an example of a second display screen W2 that displays the conventional apparent power Sc and the conventional power factor ηc.

[0061] The first display screen W1 has a mode designation tool MT for designating whether or not to eliminate induced voltage, a judgment value setting tool IT1 for setting a judgment value Ixmin for excluding induced voltage, and a threshold setting tool IT2 for setting a threshold Lmax for the number of consecutive zero current values ​​L. Using the mode designation tool MT, the user can display the characteristics of the motor under test 100 in either a first mode that displays motor characteristics including apparent power S and power factor η calculated after excluding induced voltage, or a second mode that displays conventional motor characteristics including conventional apparent power Sc and conventional power factor ηc.

[0062] On the first display screen W1, the elimination of induced voltage is set to "ON," and it is specified that the apparent power S and power factor η are calculated and displayed according to the above equations (q11) to (q16). Furthermore, the criterion value Ixmin of the current index value Ix[j], which is used to determine whether or not to eliminate induced voltage at each measurement timing j, is set to 1.2 mA. The criterion value Ixmin is preferably set to a value greater than 0, and is set in consideration of the measuring instrument's accuracy and S / N ratio according to the motor's current capacity. For example, for a micro motor such as a vibration motor in a mobile phone, the criterion value Ixmin is preferably set to several mA. Furthermore, for a large motor such as a drive motor for an electric vehicle, the criterion value Ixmin is preferably set to several A.

[0063] The threshold Lmax of the number of consecutive zero current values ​​L is set to 3. The threshold Lmax can be set to any integer equal to or greater than 2.

[0064] In the example of the first display screen W1, the root mean square of the effective voltage Er_rms, the root mean square of the effective current Is_rms, the root mean square of the induced voltage Ei_rms, the apparent power S, the active power P, and the power factor η are displayed. In this example, the power factor η is 0.95. This power factor η is a value that excludes the influence of the induced voltage and reflects the harmonic loss during the harmonic generation period P31. Therefore, it is possible to more accurately evaluate the influence of harmonic loss than in the past.

[0065] The second display screen W2 shows the calculation results when induced voltage elimination is set to "OFF." That is, this is an example of the results of calculating the conventional apparent power Sc and the conventional power factor ηc according to the above equations (q1) to (q6). In this example, the conventional power factor ηc is 0.83.

[0066] As can be seen by comparing the test results shown on the two display screens W1 and W2, the apparent power S calculated without excluding the induced voltage is smaller than the conventional apparent power Sc. Furthermore, the power factor η calculated without excluding the induced voltage is larger than the conventional power factor ηc. Because these values ​​are calculated without excluding the induced voltage, which is unrelated to the drive power, they can be considered to represent more accurate values ​​as the characteristics of the motor 100 under test. Furthermore, it is possible to more accurately evaluate the effects of harmonic loss.

[0067] The apparent power S and power factor η calculated after eliminating the induced voltage, and the conventional apparent power Sc and conventional power factor ηc may be displayed on the same screen. Furthermore, the rotation speed Nm and torque T of the motor under test 100 may be displayed together with the apparent power and power factor.

[0068] In the above-described embodiment, when the current index value Ix[j], which increases or decreases according to the current measurement value Is[j], is equal to or greater than the reference value Ixmin, the effective voltage value Er[j] is determined to be equal to the voltage measurement value Es[j]. When the current index value Ix[j] is less than the reference value Ixmin Lmax or more consecutive times, the influence of induced voltage is considered to be occurring, the induced voltage influence period is determined, and the effective voltage value Er[j] during the induced voltage influence period is determined to be equal to zero. This eliminates the influence of induced power and allows accurate calculation of apparent power and power factor. Furthermore, by referencing the accurate power factor, it is easy to determine whether the advance angle control of the motor under test 100 is appropriate.

[0069] The processing procedures of Figures 4, 5, and 6 may be modified as appropriate. In particular, the calculation method and calculation order of various values ​​may be devised to save memory capacity and improve calculation speed. The contents of the present disclosure may also be applied to calculations of apparent power and power factor using measuring instruments such as oscilloscopes. In this case, it is preferable to set the calculations using the above-mentioned equations (q1) to (q6) and (q11) to (q16) in the measuring instrument.

[0070] 6, i.e., the correction process during the correction period Pc in FIG. 2, may be omitted. In other words, the period following the measurement timing at which the number L of consecutive zero current values ​​becomes equal to or greater than the threshold Lmax may be set as the induced voltage influence period. However, by performing the correction process in step S45, it becomes possible to more accurately eliminate the induced voltage.

[0071] In the above-described embodiment, the influence of harmonic loss can be correctly evaluated, so that when harmonic countermeasures are taken for a drive device using a motor, it is possible to correctly evaluate the extent to which harmonic loss has been reduced. Furthermore, it is possible to efficiently reduce harmonic loss in a drive device using a motor.

[0072] FIG. 9 is an explanatory diagram showing the configuration of a drive device 400C in a comparative example. This drive device 400C has a PWM drive circuit 410 and a motor 420. Motor 420 is a two-phase motor having two independently connected coils, an A-phase coil 421A and a B-phase coil 421B. A-phase coil 421A is connected to PWM drive circuit 410 by A-phase positive wiring 430A1 and negative wiring 430A2. B-phase coil 421B is similarly connected to PWM drive circuit 410 by B-phase positive wiring 430B1 and negative wiring 430B2. As shown in the lower right of FIG. 9, when motor 420 is PWM-driven, harmonic oscillations occur in A-phase voltage Va and A-phase current Ia. The same is true for B-phase.

[0073] FIG. 10 is an explanatory diagram showing the configuration of a driving device 400A according to a first embodiment. This driving device A has a configuration in which harmonic filters 440A and 440B are added to the comparative example shown in FIG. 9. The first harmonic filter 440A is installed on A-phase wiring 430A1 and 430A2, and the second harmonic filter 440B is installed on B-phase wiring 430B1 and 430B2. The wiring length L1 between the harmonic filter 440A and the motor 420 is set shorter than the wiring length L2 between the harmonic filter 440A and the PWM drive circuit 410. This is because the function of the harmonic filter 440A is to reduce the impact of harmonics on the motor 420. For this reason, it is preferable to shorten the wiring length L1 between the harmonic filter 440A and the motor 420 as much as possible. The same applies to the B-phase harmonic filter 440B. In contrast, the noise filter used as a noise countermeasure is installed as close as possible to the inverter, and this differs in technical concept from harmonic filter 440A in the first embodiment.

[0074] In the example shown at the bottom of FIG. 10 , the harmonic filter 440A is configured with so-called ferrite beads. Ferrite beads are ferrite components formed into a hollow cylindrical shape. However, ferrite cores other than ferrite beads may also be used. The positive wiring 430A1 for A phase passes through the hollow portion of the ferrite core, is wound once around the ferrite core, and is then connected to the terminals of the motor 420. The number of turns of the positive wiring 430A1 in this harmonic filter 440A is 1.5. Furthermore, when observed in the direction D from the PWM drive circuit 410 toward the motor 420, the positive wiring 430A1 is wound such that after each turn, it is shifted clockwise. Similarly, when observed in the direction D from the PWM drive circuit 410 toward the motor 420, it is wound such that after each turn, it is shifted clockwise. In other words, in the harmonic filter 440A, the two A-phase wires 430A1 and 430A2 are wound around the ferrite core in the same direction. The same is true for the two B-phase wires. If the motor 420 is a three-phase motor, it is preferable to wind the wires for the three phases in the same direction around a single ferrite core. The way the wires are wound in the harmonic filter 440A differs from that of a common mode choke filter used as a noise countermeasure. That is, the technical concept of the common mode choke filter differs from that of the harmonic filter 440A of the first embodiment in that the two wires are wound in opposite directions around the ferrite core.

[0075] As shown in the lower right of FIG. 10, in the driving device 400A of the first embodiment, the harmonic oscillation phenomenon does not occur, and harmonic loss is reduced compared to the comparative example shown in FIG.

[0076] FIG. 11 is an explanatory diagram showing the configuration of a driving device 400B in the second embodiment. This driving device 400B is obtained by adding four capacitors 450C to the driving device 400A of the first embodiment shown in FIG. 10. The capacitors 450C are connected between the harmonic filters 440A, 440B and the motor 420, and between each of the wiring 430A1, 430A2, 430B1, and 430B2 and the ground potential. By adding such capacitors 450C, the harmonic reduction effect may be adjusted.

[0077] As shown in the lower part of FIG. 11, the positive side wiring 430A1 for A phase passes linearly through the hollow portion of the ferrite core of the harmonic filter 440A and is then connected to the terminal of the motor 420. The number of turns in the positive side wiring 430A1 of this harmonic filter 440A is 0.5. Note that the number of turns in the wiring may also be greater in the second embodiment. As shown in the lower right of FIG. 11, the driving device 400B of the second embodiment does not exhibit harmonic oscillation, and harmonic loss is reduced compared to the comparative example shown in FIG. 9.

[0078] According to the drive devices of the first and second embodiments described above, the wiring length L1 between the harmonic filter and the motor is set shorter than the wiring length L2 between the harmonic filter and the PWM drive circuit, thereby reducing harmonic losses in the drive device. Furthermore, in a harmonic filter for a two-phase motor, the two wires connected to the coils of each phase are wound in the same direction around a ferrite core, thereby efficiently reducing harmonic losses. In a harmonic filter for a three-phase motor, the multiple wires connected to the coils of the three phases are wound in the same direction around a single ferrite core, thereby efficiently reducing harmonic losses.

[0079] The present disclosure is not limited to the above-described embodiments, embodiments, and variations, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, embodiments, and variations corresponding to the technical features in each aspect described in the Summary of the Disclosure section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

[0080] (1) According to a first aspect of the present disclosure, there is provided a method for testing characteristics of a motor under test. This method includes the steps of: (a) measuring a coil voltage and a coil current of the motor under test at M measurement timings spanning N periods of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number ranging from 1 to M, to obtain a voltage measurement value Es[j] and a current measurement value Is[j] at the jth measurement timing; and (b) determining whether an effective voltage value Er[j] at the jth measurement timing is greater than or equal to the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value. (c) determining an induced voltage influence period by assuming that the influence of an induced voltage is occurring when the measurement timings at which the current index value is less than the judgment value occur Lmax or more times, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This method eliminates the influence of induced voltage and allows accurate calculation of apparent power and power factor. Furthermore, if the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more times, it is assumed that the influence of induced voltage is occurring, and the induced voltage influence period is determined accordingly. Therefore, the harmonic generation period and the induced voltage influence period can be distinguished so that they do not overlap, allowing for accurate evaluation of harmonic loss.

[0081] (2) In the above method, step (b) may include determining that the induced voltage value Ei[j] at the jth measurement timing is equal to zero when the current index value is equal to or greater than the judgment value, and step (c) may include determining that the induced voltage value Ei[j] is equal to the voltage measurement value Es[j] when the current index value is less than the judgment value. According to this method, the induced voltage value can be calculated.

[0082] (3) In the above method, the step (d) may include: (d1) calculating the apparent power by multiplying the root mean square of the effective voltage value Er[j] obtained at the M measurement times by the root mean square of the current measurement value Is[j] obtained at the M measurement times; (d2) calculating the active power by multiplying the voltage measurement value Es[j] by the current measurement value Is[j] to obtain an active power value Pe[j] and calculating the root mean square of the active power value Pe[j] obtained at the M measurement times; and (d3) calculating the power factor by dividing the active power by the apparent power. According to this method, the apparent power, the effective power, and the power factor can be calculated by simple calculations.

[0083] (4) The above method may further include the steps of: calculating a conventional apparent power by multiplying the root mean square of the voltage measurement values ​​Es[j] obtained at the M measurement times by the root mean square of the current measurement values ​​Is[j] obtained at the M measurement times; and calculating a conventional power factor by dividing the active power by the conventional apparent power. According to this method, conventional apparent power and conventional power factor can be calculated using conventional methods.

[0084] (5) A second aspect of the present disclosure provides a characteristic test device for testing the characteristics of a motor under test, comprising: a measurement acquisition unit that acquires a voltage measurement value Es[j] and a current measurement value Is[j] at a j-th measurement timing by measuring the coil voltage and coil current of the motor under test at M measurement timings spanning N periods of the coil voltage, where N is an integer greater than or equal to 1, M is an integer greater than N, and j is an ordinal number from 1 to M; and a characteristic calculation unit that calculates the characteristics of the motor under test using the voltage measurement value Es[j] and the current measurement value Is[j]. The characteristic calculation unit is configured to execute the following processes: determining that the effective voltage value Er[j] at the jth measurement timing is equal to the voltage measurement value Es[j] when a current index value, which increases or decreases according to the current measurement value Is[j], is equal to or greater than a predetermined judgment value; determining an induced voltage influence period by assuming that an induced voltage influence is occurring when the measurement timings at which the current index value is less than the judgment value occur Lmax or more times, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This characteristic test device can calculate accurate apparent power and power factor by eliminating the influence of induced voltage. Furthermore, if the measurement timing at which the current index value is less than the judgment value occurs Lmax times or more in succession, it is assumed that the influence of induced voltage is occurring and the induced voltage influence period is determined. Therefore, it is possible to distinguish between the harmonic generation period and the induced voltage influence period so that they do not overlap, and harmonic loss can be correctly evaluated.

[0085] (6) The characteristic test device may further include a characteristic display unit that displays the characteristics of the motor under test calculated by the characteristic calculation unit on a display screen, and the characteristic display unit may display a mode designation tool on the display screen to designate either a first mode that displays the apparent power and the power factor, or a second mode that displays the conventional apparent power and conventional power factor calculated by a conventional method. This characteristic test device can display, according to the user's specification, either apparent power and power factor that eliminate the influence of induced voltage, or conventional apparent power and conventional power factor that do not eliminate the influence of induced voltage.

[0086] (7) In the above characteristic test device, the characteristic display unit may further display a judgment value setting tool for setting the judgment value on the display screen. This characteristic test device allows the user to set the judgment value as desired.

[0087] (8) According to a third aspect of the present disclosure, there is provided a computer program for executing a process of testing characteristics of a motor under test. This computer program includes: (a) a process of measuring a coil voltage and a coil current of the motor under test at M measurement timings over a period of N periods of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number from 1 to M, thereby obtaining a voltage measurement value Es[j] and a current measurement value Is[j] at the jth measurement timing; and (b) a process of determining whether an effective voltage value Er[j] at the jth measurement timing is equal to or greater than the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value. (c) determining that the effective voltage value Er[j] is equal to zero when the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more, where Lmax is an integer equal to or greater than 2; determining an induced voltage influence period by assuming that the influence of induced voltage is occurring and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; and (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings. This computer program can accurately calculate apparent power and power factor by eliminating the influence of induced voltage. Furthermore, if the number of consecutive measurement timings at which the current index value is less than the judgment value is Lmax or more times, it is assumed that the influence of induced voltage is occurring, and the period affected by induced voltage is determined accordingly. Therefore, it is possible to distinguish between the harmonic generation period and the induced voltage influence period so that they do not overlap, enabling accurate evaluation of harmonic loss.

[0088] (9) A fourth aspect of the present disclosure provides a drive device including a PWM drive circuit and a motor, the drive device further including a harmonic filter disposed between the PWM drive circuit and the motor, the harmonic filter configured such that the wiring length between the motor and the harmonic filter is shorter than the wiring length between the PWM drive circuit and the harmonic filter. This driving device can reduce harmonic losses during PWM driving. [Explanation of symbols]

[0089] 100...motor under test, 101...A phase coil, 104...magnetic sensor, 110...rotating shaft, 120...drive circuit, 130...constant voltage power supply, 151...ammeter, 161...voltmeter, 200...motor testing device, 211...first coupling, 212...second coupling, 220...torque meter, 221...first rotating shaft, 222...second rotating shaft, 230...electric brake, 232...rotating shaft, 234...magnetic sensor, 240...A C / DC conversion unit, 250... DC load unit, 260... measurement value collection unit, 270... test connection structure, 300... characteristic test device, 310... measurement value acquisition unit, 320... characteristic calculation unit, 330... characteristic display unit, 400A, 400B, 400C... drive unit, 410... PWM drive circuit, 420... motor, 430A1, 430A2, 430B1, 430B2... wiring, 440A, 440B... harmonic filter, 450C... capacitor

Claims

1. 1. A method for testing characteristics of a motor under test, comprising: (a) obtaining a voltage measurement value Es[j] and a current measurement value Is[j] at a j-th measurement timing by measuring the coil voltage and the coil current of the motor under test at M measurement timings over a period of N periods of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number from 1 to M; (b) determining that the effective voltage value Er[j] at the j-th measurement timing is equal to the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined determination value; (c) determining an induced voltage influence period by determining that an induced voltage influence is occurring when the measurement timing at which the current index value is less than the judgment value occurs Lmax times or more, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings; A method comprising:

2. 10. The method of claim 1, the step (b) includes determining that the induced voltage value Ei[j] at the j-th measurement timing is equal to zero when the current index value is equal to or greater than the determination value; The method, wherein step (c) includes determining that the induced voltage value Ei[j] is equal to the measured voltage value Es[j] when the current index value is less than the determination value.

3. 10. The method of claim 1, The step (d) (d1) calculating the apparent power by multiplying the root mean square of the effective voltage value Er[j] obtained at the M measurement times by the root mean square of the measured current value Is[j] obtained at the M measurement times; (d2) calculating an active power by multiplying the voltage measurement value Es[j] by the current measurement value Is[j] to obtain an active power value Pe[j] and calculating the root mean square of the active power values ​​Pe[j] obtained at the M measurement timings; (d3) calculating the power factor by dividing the real power by the apparent power; A method comprising:

4. 4. The method of claim 3, further comprising: calculating conventional apparent power by multiplying the root mean square of the voltage measurement values ​​Es[j] obtained at the M measurement times by the root mean square of the current measurement values ​​Is[j] obtained at the M measurement times; calculating a conventional power factor by dividing the real power by the conventional apparent power; A method comprising:

5. A characteristic test device for testing the characteristics of a motor under test, a measurement value acquisition unit that acquires a voltage measurement value Es[j] and a current measurement value Is[j] at a j-th measurement timing by measuring a coil voltage and a coil current of the motor under test at M measurement timings over a period of N cycles of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number from 1 to M; a characteristic calculation unit that calculates the characteristics of the motor under test using the voltage measurement value Es[j] and the current measurement value Is[j]; Equipped with The characteristic calculation unit a process of determining that the effective voltage value Er[j] at the j-th measurement timing is equal to the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value; a process of determining an induced voltage influence period by determining that an influence of an induced voltage is occurring when the measurement timing at which the current index value is less than the judgment value occurs Lmax times or more, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; A process of calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings; A characteristic test device configured to perform the following:

6. The characteristic test apparatus according to claim 5, further comprising: a characteristic display unit that displays the characteristics of the motor under test calculated by the characteristic calculation unit on a display screen, The characteristic display unit displays on the display screen a mode designation tool for designating either a first mode for displaying the apparent power and the power factor, or a second mode for displaying conventional apparent power and conventional power factor calculated by a conventional method.

7. 7. The characteristic test apparatus according to claim 6, The characteristic display unit further displays a judgment value setting tool for setting the judgment value on the display screen.

8. A computer program for executing a process for testing characteristics of a motor under test, comprising: (a) obtaining a voltage measurement value Es[j] and a current measurement value Is[j] at a j-th measurement timing by measuring the coil voltage and the coil current of the motor under test at M measurement timings over a period of N periods of the coil voltage, where N is an integer equal to or greater than 1, M is an integer greater than N, and j is an ordinal number from 1 to M; (b) determining that the effective voltage value Er[j] at the j-th measurement timing is equal to the voltage measurement value Es[j] when a current index value that increases or decreases according to the current measurement value Is[j] is equal to or greater than a predetermined judgment value; (c) determining an induced voltage influence period by determining that the influence of an induced voltage is occurring when the measurement timing at which the current index value is less than the judgment value occurs Lmax times or more, where Lmax is an integer equal to or greater than 2, and determining that the effective voltage value Er[j] during the induced voltage influence period is equal to zero; (d) calculating the apparent power and power factor of the motor under test from the effective voltage value Er[j], the voltage measurement value Es[j], and the current measurement value Is[j] obtained at the M measurement timings; A computer program that causes a computer to execute the following.

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