Motor testing apparatus, and method for measuring the characteristics of a motor under test using the motor testing apparatus.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MIYAWAKI KOBO CO LTD
- Filing Date
- 2022-07-28
- Publication Date
- 2026-08-05
Smart Images
Figure 0007900819000001 
Figure 0007900819000002 
Figure 0007900819000003
Abstract
Description
Technical Field
[0006] , ,
[0005] , ,
[0001] The present disclosure relates to a motor test device and a method for measuring the characteristics of a motor under test using the same.
Background Art
[0002] Patent Document 1 describes a motor test device for measuring the characteristics of a motor under test. In this motor test device, a motor under test and a load motor are connected via a gear, and a controller drives the load motor according to a speed command input from a simulator unit that outputs a speed command to the load motor.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
[0007] [Figure 1] A block diagram showing the configuration of the motor test system in the first embodiment. [Figure 2] A graph showing the IT characteristics of electric brakes. [Figure 3] A diagram showing an example of the internal configuration of an AC / DC converter. [Figure 4] An explanatory diagram showing the operation of a polarity separation circuit. [Figure 5] A diagram showing an example of the internal configuration of a DC load section. [Figure 6] An explanatory diagram showing an example of a load pattern in transient response testing. [Figure 7] A graph showing the loss characteristics of a motor testing device. [Figure 8]A graph showing the loss characteristics of a motor testing device. [Figure 9] An explanatory diagram showing the process for determining the loss TN characteristics of a motor testing device. [Figure 10] A flowchart showing the procedure for testing the TN characteristics of the motor under test. [Figure 11] A graph showing the efficiency of the motor under test in a motor testing device. [Figure 12] A graph showing an example of the TN characteristics of the motor under test. [Figure 13] A block diagram showing the configuration of a motor test system for measuring the starting torque of a motor under test, according to the second embodiment. [Figure 14] An explanatory diagram showing the principle of measuring the starting torque of the motor under test in the second embodiment. [Figure 15] Flowchart for measuring the starting torque of the motor under test in the second embodiment. [Figure 16] A graph showing the starting torque of the motor under test alone, obtained in the second embodiment. [Figure 17] A block diagram showing the configuration of a motor test system for measuring the starting torque of a motor under test, according to the third embodiment. [Figure 18] Flowchart for measuring the starting torque of the motor under test in the third embodiment. [Figure 19] A graph showing the starting torque of the motor under test alone, obtained in the third embodiment. [Figure 20] A block diagram showing the configuration of a motor test system for measuring the starting torque of a motor under test, according to the fourth embodiment. [Figure 21] Flowchart for measuring the starting torque of the motor under test in the fourth embodiment. [Figure 22] This is an explanatory diagram showing the state in which a rectangular pulse voltage is applied to a specific phase coil in the fourth embodiment. [Modes for carrying out the invention]
[0008] A. First Embodiment: FIG. 1 is a block diagram showing the configuration of a motor test system according to the first embodiment. This motor test system includes a DUT (Device Under Test) motor 100, a motor test apparatus 200, and a test control apparatus 300.
[0009] As the DUT motor 100, any type of motor having an arbitrary number of phases can be used. In this embodiment, the DUT motor 100 has a magnetic sensor 104 that measures the rotational position of the rotor. However, when the DUT motor 100 is sensorless-driven, the magnetic sensor 104 can be omitted. The DUT motor 100 is electrically connected to a drive circuit 120. A DC input voltage Ei is supplied to the drive circuit 120 from a constant voltage power supply 130. The voltage value of the input voltage Ei can be adjusted by the test control apparatus 300. The drive circuit 120 is, for example, a motor driver configured as an H-bridge circuit, and the transistors in the drive circuit 120 turn on / off in response to a control signal Sd supplied from the test control apparatus 300. The control signal Sd is, for example, a signal for performing PWM control of the DUT motor 100. In PWM control, the rotational position of the DUT motor 100 is detected according to the output of the magnetic sensor 104, and the control signal Sd for each phase is generated according to this rotational position. An input ammeter 150 that measures the input current Ii and an input voltmeter 160 that measures the input voltage Ei are provided in the wiring between the constant voltage power supply 130 and the drive circuit 120. A phase ammeter 151 that measures the phase current Is of each phase and a phase voltmeter 161 that measures the phase voltage Es of each phase are provided in the wiring between the drive circuit 120 and the non-test motor 100. The ammeters 150, 151 and the voltmeters 160, 161 are used to obtain the input power to the DUT motor 100. Incidentally, it is preferable that the constant voltage power supply 130 is configured to perform voltage supply by remote sensing that detects the terminal voltage of the drive circuit 120, so as to reduce the voltage drop and voltage fluctuation between lines.
[0010] The motor test 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 power meter 260. A 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.
[0011] The rotating shaft 110 of the motor under test 100 and the first rotating shaft 221 of the torque meter 220 are connected by the 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 be able to measure the rotational speed N of the rotating shafts 221, 222. Instead of measuring the rotational speed N with the torque meter 220, the rotational speed N may be measured using a magnetic sensor 104 provided on 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 the second coupling 212. The electric brake 230 has a coreless motor structure with low iron losses (cogging loss, hysteresis loss, etc.). The electric brake 230 is configured as, for example, a two-phase or three-phase brushless motor. In the present embodiment, the electric brake 230 has a magnetic sensor 234 that measures the rotational position of the rotor. In the present 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 on the rotor. The magnetic sensor 234 is constituted by, for example, a Hall IC. However, the magnetic sensor 234 can be omitted.
[0012] The AC / DC conversion unit 240 is electrically connected to a plurality of phases of coils of the electric brake 230, and full-wave rectifies the alternating current induced voltage Vi generated in the coils to convert it into a direct current voltage Vd. The DC load unit 250 is electrically connected to the AC / DC conversion unit 240 and consumes power by the direct current voltage Vd. The DC load unit 250 has a variable current control unit 252 that variably adjusts the direct current value and a resistor 256. Specific examples of the AC / DC conversion unit 240 and the DC load unit 250 will be described later.
[0013] The power meter 260 calculates rotational energy P [W] from torque T [N·m] and rotational speed N [rpm] according to the following formula. P = T × 2πN / 60 …(1) Torque T, rotational speed N, and rotational energy P are supplied from the power meter 260 to the test control device 300. The power meter 260 uses multiple input signals, including the input voltage value Ei measured by the input voltmeter 160, the input current value Ii measured by the input ammeter 150, the torque T and rotational speed N measured by the torque meter 220, the phase voltage value Es measured by the phase voltmeter 161, and the phase current value Is measured by the phase ammeter, to calculate the effective value, effective value, and power factor of the output of the motor 100 under test.
[0014] The test control device 300 controls various parts of the motor test device 200, and also controls the drive circuit 120 and constant voltage power supply 130 of the motor under test 100. The test control device 300 can be implemented, for example, by a personal computer. Various tests on the motor under test 100 are performed by the processor executing an application program for motor testing stored in memory 310.
[0015] In this embodiment, the electric brake 230 has a coreless motor structure. The coreless motor structure has the following advantages compared to a motor structure with a core. (a) Because it does not use an iron core, the coil inductance is small. (b) No cogging loss or hysteresis loss. (c) There is no magnetic saturation of the coil current due to the iron core characteristics.
[0016] Since the coil inductance of the electric brake 230 is extremely small, the transient response characteristics of the motor 100 under test to rapid transient changes can be accurately measured. The self-inductance of each phase coil of the electric brake 230 is preferably, for example, 4 μH or less. Furthermore, since the electric brake 230 has no cogging loss or hysteresis loss, it can provide a stable load to the motor 100 under test.
[0017] Figure 2 is a graph showing the IT characteristics of the electric brake 230. The black dots represent measured points. As can be seen from this figure, since the electric brake 230 does not experience coil magnetic saturation, it is possible to obtain torque proportional to the coil current when the coil current increases. In other words, a load proportional to the coil current of the electric brake 230 can be applied to the motor under test 100. Furthermore, since the electric brake 230 of this embodiment has extremely low losses, the IT characteristics are almost a straight line passing through the origin.
[0018] Since the electric brake 230 has a coreless motor structure, iron loss is negligible, and mechanical loss due to bearings and other components is also extremely low. For example, the mechanical loss of the electric brake 230 is preferably 10 watts or less at a rotational speed of 10,000 rpm. By using such a low-loss electric brake 230, the transient response characteristics of the motor under test to sudden transient changes can be accurately tested. A low-loss electric brake 230 can be realized, for example, in a two-phase or three-phase coreless electromechanical device as described in WO2018-139245A1.
[0019] Figure 3 shows an example of the internal configuration of the AC / DC converter 240. The AC / DC converter 240 includes a full-wave rectifier circuit 241A for the A-phase coil 231A of the electric brake 230, a full-wave rectifier circuit 241B for the B-phase coil 231B, a smoothing capacitor 242, a polarity separation circuit 243A for the A-phase, and a polarity separation circuit 243B for the B-phase. In this embodiment, the full-wave rectifier circuits 241A and 241B are configured as MOSFET bridge circuits with low voltage drop. The polarity separation circuits 243A and 243B generate polarity signals Pa and Pb indicating the A-phase and B-phase intervals according to the sensor outputs MPa and MPb of the A-phase magnetic sensor 234A and B-phase magnetic sensor 234B of the electric brake 230.
[0020] Figure 4 is an explanatory diagram showing the operation of polarity separation circuits 243A and 243B. The sensor output MPa of the A-phase magnetic sensor 234A shows a sinusoidal waveform corresponding to the rotational position of the permanent magnet of the rotor of the electric brake 230. The sensor output MPb of the B-phase magnetic sensor 234B is similar. Polarity separation circuit 243A generates a first polarity signal Pa+ that rises from L level to H level at the zero-crossing position of the sensor output MPa, and a second polarity signal Pa- that falls from H level to L level at the zero-crossing position of the sensor output MPa. Similarly, polarity separation circuit 243B generates a first polarity signal Pb+ that rises from L level to H level at the zero-crossing position of the sensor output MPb, and a second polarity signal Pb- that falls from H level to L level at the zero-crossing position of the sensor output MPb. These polarity signals Pa+, Pa-, Pb+, and Pb- are used as gate signals for the MOSFETs of the full-wave rectifier circuits 241A and 241B. As a result, the induced AC voltage generated in the A-phase coil 231A and the induced AC voltage generated in the B-phase coil 231B are converted into a DC voltage Vdc by the full-wave rectifier circuits 241A and 241B. The DC voltage Vdc is smoothed by the smoothing capacitor 242 and output from the output terminals 246p and 246n. In this way, by using an AC / DC converter 240 having full-wave rectifier circuits 241A and 241B composed of MOSFETs, power loss by the AC / DC converter 240 can be kept to a minimum. However, the AC / DC converter 240 may also be configured using a full-wave rectifier circuit composed of diodes.
[0021] Figure 5 shows an example of the internal configuration of the DC load unit 250. The DC load unit 250 has a configuration in which a variable current control unit 252 and a resistor 256 are arranged in series between two input terminals 251p and 251n. The variable current control unit 252 is configured as a constant current circuit that can variably adjust the DC current value flowing through the resistor 256. In this embodiment, the variable current control unit 252 has a transistor 253, an operational amplifier 254, and a current command unit 255. The current command unit 255 inputs a current command value Vt to the operational amplifier 254 in response to a command from the test control device 300. The output of the operational amplifier 254 is supplied to the gate electrode of the transistor 253. The output voltage Vm of the transistor 253 is fed back to the operational amplifier 254, and the operational amplifier 254 adjusts the level of the gate signal of the transistor 253 according to the difference between the output voltage Vm of the transistor 253 and the current command value Vt. As a result, a DC current with a current value Ir corresponding to the current command value Vt flows from transistor 253 to resistor 256.
[0022] Thus, by using a DC load unit 250 having a configuration in which a variable current control unit 252 and a resistor 256 are connected in series, the induced electromotive force generated by the electric brake 230 can be consumed by the resistor 256 at a constant current value. As a result, it is possible to provide a stable load torque to the motor 100 under test.
[0023] Figure 6 is an explanatory diagram showing examples of load patterns P1 to P4 in transient response testing. In the motor test system of this embodiment, transient response testing of the motor under test 100 can be performed according to these various load patterns. In particular, since an electric brake 230 with a coreless motor structure is used as the load device in this embodiment, transient response characteristics involving rapid transient changes can be tested. For example, load patterns P1, P2, and P4 all include nearly vertical load changes. Load patterns P1, P2, and P4, which involve such rapid transient changes, cannot be realized when a motor with a core is used as the load device.
[0024] When performing transient response testing, a predetermined load pattern is stored in the memory 310 of the test control device 300, and feedback control is performed using that load pattern. Specifically, the load torque of the load pattern is set as the target value, the torque measured by the torque meter 220 is set as the control variable, and the current command value of the DC load unit 250 is set as the manipulated variable. That is, the current command value of the DC load unit 250 is adjusted so that the difference between the target load torque of the load pattern and the torque measured by the torque meter 220 becomes zero.
[0025] The motor test device 200 can be used for various measurements and tests, including transient response testing, as well as measuring TN characteristics and starting torque characteristics. The inventors of this disclosure have found that the influence of losses in the motor test device 200 is significant when measuring the TN characteristics of the motor under test 100. As described below, by correcting the torque measured in the TN characteristic measurement of the motor under test 100 with a loss torque corresponding to the losses in the motor test device 200, it is possible to obtain more accurate TN characteristics.
[0026] Figure 7 is a graph showing the loss-speed characteristics of the motor test device 200. The first loss Pd is the loss of the motor test device 200 when the motor under test 100 is not connected to the first coupling 211. The second loss Pb is the loss of the electric brake 230 alone. As can be seen from this figure, the loss Pb of the electric brake 230 is extremely small. Since the iron loss of the electric brake 230 is almost negligible, its loss Pb can be considered as mechanical loss. The loss Pb of the electric brake 230 is preferably 10 watts or less at a rotational speed of 10,000 rpm. By using an electric brake 230 with such low losses, the transient response characteristics of the motor under test to rapid transient changes can be accurately tested.
[0027] Figure 8 is a graph showing the loss TN characteristics of the motor test device 200. The first loss torque Td is the torque corresponding to the loss of the motor test device 200 when the motor under test 100 is not connected to the first coupling 211, and is calculated from the loss Pd shown in Figure 7 according to equation (1) above. The second loss torque Tb is the loss of the electric brake 230 alone, and is calculated from the loss Pb shown in Figure 7 according to equation (1) above. The lower part of Figure 8 shows an enlarged view of the vertical axis of the loss torque Tb of the electric brake 230 alone. The reason why the loss torque Tb increases sharply when the rotational speed is approximately 5000 rpm or higher is presumed to be due to mechanical loss in the bearing of the electric brake 230.
[0028] The loss TN characteristics of the motor test device 200 when the motor under test 100 is not connected are stored in the memory 310 of the test control device 300 and used to correct the TN characteristics of the motor under test 100.
[0029] Figure 9 is an explanatory diagram showing the process for determining the loss TN characteristics of the motor test device 200. In step S1, the motor under test 100 is rotated under no load without being connected to the motor test device 200, and the torque Ts0, output Ps0, and rotational speed N are measured. This measurement is performed with the input voltage Ei to the drive circuit 120 of the motor under test 100 set to several different values. In addition, the current flowing through the DC load section 250 is set to 0 so that no braking action occurs in the electric brake 230. Alternatively, the connection between the electric brake 230 and the AC / DC converter 240 may be disconnected.
[0030] The torque Ts0 [N·m] of the motor under test 100 is calculated using the output Ps0 [W] and rotational speed N [rpm] of the motor under test 100 according to the following formula. Ts0 = Ps0 × 60 / 2πN …(2)
[0031] In step S2, with the motor under test 100 connected to the motor test device 200, the motor under test 100 is rotated under no load, as in step S1, and the torque Ts1, output Ps1, and rotational speed N are measured using the torque meter 220. This measurement is also performed, as in step S1, with the input voltage Ei to the drive circuit 120 of the motor under test 100 set to several different values.
[0032] In step S3, the loss Pd of the motor test device 200 and the loss torque Td corresponding to the loss Pd are calculated using the following formulas, based on the results of steps S1 and S2. Pd = Ps1 - Ps0 …(3a) Td = Ts1 - Ts0 …(3b)
[0033] Steps S1 and S2 are performed with the input voltage Ei set to multiple values, so the loss torque Td is calculated according to multiple rotational speeds N.
[0034] The steps S1 to S3 described above allow for the creation of the loss TN characteristics of the motor test device 200 when the motor under test 100 is not connected. These loss TN characteristics can be stored in the memory 310. As described below, the test control device 300 uses these loss TN characteristics to correct the TN characteristics of the motor under test 100.
[0035] Figure 10 is a flowchart showing the procedure for testing the TN characteristics of the motor under test 100. In step S10, the TN characteristics of the motor under test 100 are measured while the motor under test 100 is connected to the motor test device 200. This measurement is performed for a specific input voltage Ei. In step S20, the loss TN characteristics of the motor test device 200 are read from the memory 310 of the test control device 300. In step S30, the TN characteristics of the motor under test 100 are corrected using the loss TN characteristics of the motor test device 200. That is, the corrected TN characteristics for the motor under test 100 are obtained by adding the loss torque Td of the loss TN characteristics shown in Figure 8 to the torque of the TN characteristics of the motor under test 100. By performing the process in Figure 10, it is possible to obtain the corrected TN characteristics of the motor under test 100 alone, which do not include the loss torque component corresponding to the loss of the motor test device 200.
[0036] Figure 11 is a graph showing the efficiency of the motor under test 100 before and after loss correction in the motor test device 200. The horizontal axis of this graph is torque, and the vertical axis is efficiency (= output / input). The output of the motor under test 100 is calculated according to equation (1) above, based on the torque T measured by the torque meter 220 and the rotational speed N. The input of the motor under test 100 is calculated by multiplying the phase current value Is measured by the phase ammeter 151, the phase voltage value Es measured by the phase voltmeter 161, and the power factor. The graph before correction shows the efficiency corresponding to the TN characteristics obtained in step S10 of Figure 10, and the graph after correction shows the efficiency corresponding to the corrected TN characteristics after correction in step S30. The corrected efficiency can be considered to represent the true efficiency of the motor under test 100.
[0037] As can be seen from the graph in Figure 11, in a rotational state where the torque T is small and close to no load, the influence of the losses of the motor test device 200 is quite large. As a result, in the normal TN characteristics obtained in step S10 of Figure 10, the torque and efficiency of the motor under test 100 tend to be lower than the true values. On the other hand, by correcting the torque and output of the motor under test 100 using the loss torque Td, which corresponds to the losses of the motor test device 200, the true torque and efficiency of the motor under test 100 can be calculated correctly.
[0038] Figure 12 is a graph showing an example of the TN characteristics of the motor under test 100. These TN characteristics are for a constant input voltage Ei and are the characteristics after correction according to Figure 10. The dashed line indicates the test region, which is the range in which measurements can be performed in a normal TN characteristic test. The starting torque Ts at zero rotational speed N can be obtained by extrapolating the TN characteristics in the test region.
[0039] As described above, in the first embodiment, an electric brake 230 having a coreless motor structure is used, and the AC induced voltage of the electric brake 230 generated by the rotation of the motor 100 under test is converted into a DC voltage and the power is consumed by the DC load section 250, so that the transient response characteristics of the motor 100 under test to sudden transient changes can be tested.
[0040] The motor testing device 200 can also be used as a device for performing various tests, such as the following: (1) A device for measuring the characteristics of a motor under test 100, which normally has a PWM frequency of about 20 kHz, when high-resolution electrical angle control is performed by making the electrical angle control more precise and increasing the PWM frequency to 100 kHz to 200 kHz or higher. (2) A device for evaluating the characteristics of the forward and reverse rotation control of a propeller, such as transient response and self-balancing controllability, in order to adapt to transient changes in natural environments such as updrafts and turbulence, using a motor used in a drone as the motor under test 100. (3) A device for evaluating characteristics such as transient response and self-balancing controllability in order to improve the transient response of a motor used for rudder and flap operation in the aerospace industry, such as the motor under test 100, and to adapt to transient changes such as turbulence in the natural environment. (4) A device for evaluating the characteristics of heat exchangers, ventilators, high-concentration oxygen generators, water-spraying fire pumps, etc., which involve compressing with high torque over a short period of time, using a motor used in a fluid compression device as the motor under test 100.
[0041] B. Second Embodiment: The starting torque Ts obtained by conventional measurement methods is greatly affected by the driving characteristics of the drive circuit 120 (transistor on-resistance, voltage attenuation of circuit board wiring, drive waveform, phase angle, etc.). In the second embodiment, a method for measuring the starting torque Ts without being affected by the driving characteristics of the drive circuit 120 will be described.
[0042] Figure 13 is a block diagram showing the configuration of a motor test system for measuring the starting torque of the motor under test 100 in the second embodiment. The differences in the system configuration between the second embodiment and the first embodiment are three: a constant current power supply 140 is used instead of a constant voltage power supply 130; the drive circuit 120 for the motor under test 100 is omitted; and a drive circuit 235 is provided to drive the electric brake 230 as a motor. The other configurations are the same as in the first embodiment. Although the constant voltage power supply 130 and the constant current power supply 140 are described separately for illustrative purposes, a constant voltage / constant current power supply that integrates both functions may also be used. This is also true for other embodiments described later.
[0043] Figure 14 is an explanatory diagram illustrating the principle of measuring the starting torque of the motor under test 100 in the second embodiment. The upper part of Figure 14 shows the PWM waveform of the A-phase coil and the torque change generated in the A-phase coil in the normal driving state of the motor under test 100. Here, it is assumed that the motor under test 100 is a two-phase motor, but the measurement principle is almost the same for motors with three or more phases. The PWM waveform is the effective voltage waveform applied to the A-phase coil and has an almost sinusoidal shape. A sinusoidal torque is generated from the A-phase coil in accordance with this PWM waveform. This torque change can be considered as a change in torque corresponding to the rotation angle of the motor under test 100. Furthermore, the maximum value of this torque change is equal to the starting torque Ts of the motor under test 100.
[0044] Considering the torque generation principle under such normal driving conditions, it can be understood that the starting torque Ts of the motor under test 100 can be measured by measuring the change in torque generated from the A-phase coil according to the rotation angle and determining its maximum value. Therefore, in the second embodiment, as shown in the lower part of Figure 14, with a constant input current value of DC power input to the A-phase coil, the rotation shaft of the motor under test 100 is rotated by driving the electric brake 230 with the drive circuit 235, and the change in torque is measured with the torque meter 220, and its maximum value is measured as the starting torque Ts. It is preferable to measure the torque over a range of rotation angles Δθ corresponding to at least 2π in electrical angle. Although the starting torque Ts can be obtained with only the A-phase single-phase, it is also possible to obtain the starting torque Ts for the B-phase coil in the same way, taking into account phase variations.
[0045] Figure 15 is a flowchart of the starting torque measurement of the motor 100 under test in the second embodiment. In the second to fourth embodiments, when M is an integer of 2 or more, it is assumed that the motor 100 under test is a coreless motor having M-phase coils. Typical examples are M being 2 or 3. However, the motor 100 under test may be a motor with a core.
[0046] In step S110, a DC current of a constant value is input to one of the M-phase coils of the motor under test 100, and the input voltage to the specific phase coil is measured. If the motor under test 100 is a two-phase motor, one of the A-phase coil and the B-phase coil is selected as the specific phase coil and a DC current is input to it, while no DC current is input to the other. If the motor under test 100 is a three-phase motor, one of the U-phase coil, V-phase coil, and W-phase coil is selected as the specific phase coil and a DC current is input to it, while no DC power is input to the other two phase coils. However, if the U-phase coil is selected as the specific phase coil, the DC current input to the U-phase coil flows through the U-phase coil to both the V-phase coil and the W-phase coil. The current value Ii of the DC current input to the specific phase coil is measured with an input ammeter 150, and the input voltage value Ei is measured with an input voltmeter 160.
[0047] In step S120, with the same constant DC current as in step S110 supplied to the specific phase coil of the motor under test 100, rotation is applied to the motor under test 100 by the electric brake 230, and the maximum torque of the torque change accompanying the rotation is measured by the torque meter 220. At this time, it is preferable that the rotation range of the motor under test 100 be 2π or more in terms of the electrical angle of the motor under test 100. As shown in Figure 14, the torque of a motor depends on the electrical angle and shows a sinusoidal waveform that peaks in the rotation angle range of 2π in terms of electrical angle. Therefore, by rotating the motor under test 100 over a rotation angle range of 2π or more in terms of electrical angle, it is possible to determine the maximum torque generated by the motor under test 100.
[0048] The control of applying rotation to the motor under test 100 using the electric brake 230 is performed by the drive circuit 235. In step S120, the torque may be measured while the rotation shaft 110 of the motor under test 100 is slowly rotated, or the torque may be measured with the rotation shaft 110 of the motor under test 100 stopped at multiple rotation angles.
[0049] In step S130, it is determined whether to perform the processes in steps S110 and S120 with other current values. In the second embodiment, steps S110 and S120 are performed with multiple current values. If the processes in steps S110 and S120 are performed with other current values, the process proceeds to step S140, where the DC current value is changed and the process returns to step S110. In this way, by performing steps S110 and S120 with multiple current values, multiple maximum torques corresponding to multiple input voltages can be determined for a single specific phase coil.
[0050] In step S150, it is determined whether or not to perform the processes described in steps S110 to S140 using the coils of other phases. If the processes in steps S110 to S140 have not been completed for all of the M-phase coils of the motor under test 100, the process returns from step S150 to step S110, the specific phase coil is changed, and steps S110 to S140 are executed again. Once the processes in steps S110 to S140 have been completed for all of the M-phase coils, the process proceeds to step S160.
[0051] In step S160, a starting torque characteristic curve showing the change in starting torque according to multiple input voltages is created from the M maximum torques obtained for each of the multiple input voltages applied to the M-phase coil of the motor 100 under test. At this time, the starting torque of the motor 100 under test is determined from the M maximum torques obtained for each individual input voltage applied to the M-phase coil. For example, the average value, maximum value, or minimum value of the M maximum torques can be determined as the starting torque. If the average value of the maximum torques is selected as the starting torque, the expected value of the starting torque expected from the motor 100 under test can be used as the starting torque. Also, if the maximum value of the maximum torques is selected as the starting torque, the starting torque can be set to the torque that can be generated when the rotating shaft 110 of the motor 100 under test is in the rotation position most favorable for torque generation. If the minimum value of the maximum torques is selected as the starting torque, the starting torque can be set to the torque that can be generated when the rotating shaft 110 of the motor 100 under test is in the rotation position least favorable for torque generation.
[0052] It is not necessary to perform steps S110 to S140 for all M-phase coils; steps S110 to S140 may be performed for at least one phase coil. For example, if steps S110 to S140 are performed for only one phase coil, the maximum torque obtained for that coil will be determined as the starting torque.
[0053] Figure 16 is a graph showing the starting torque characteristics of the motor 100 under test obtained in the second embodiment. In Figure 16, the horizontal axis represents the input voltage, and the vertical axis represents the starting torque. Multiple black circles indicate measurement points, and the dotted line shows the starting torque characteristic curve G2 created from multiple measurement points.
[0054] The starting torque characteristic curve G2 can be represented by an approximation function that approximates multiple measurement points. In the example in Figure 16, the starting torque characteristic curve G2 is a straight line. If the motor under test 100 is a coreless motor, the starting torque characteristic curve G2 can be represented by a straight line. Normally, the input voltage Ei measured in the process in Figure 15 is an extremely small value compared to the rated voltage of the motor under test 100. In the example in Figure 16, when the rated voltage of the motor under test 100 is 10[V], the value of the input voltage Ei at the measurement point is 1 / 10 or less of that. This is because if the DC voltage value is set to a large value so that the input voltage Ei is close to the rated voltage, the coil of the motor under test 100 may overheat, potentially damaging the motor under test 100. Furthermore, the key point of this test is to measure without being affected by the heat generated by the motor under test 100 itself. In this sense, it is even more preferable to set the input voltage Ei in the process in Figure 15 to 1 / 10 or less of the rated voltage of the motor under test 100.
[0055] In step S170, the starting torque for a specific voltage higher than the multiple input voltages used in the measurements in steps S110 to S140 is calculated by extrapolating the starting torque characteristic curve G2. In the example in Figure 16, the specific voltage is set to 10V, and the starting torque Ts for that specific voltage is calculated by extrapolating the starting torque characteristic curve G2. In this embodiment, since the starting torque characteristic curve G2 is linear, it is possible to accurately determine the starting torque Ts for a specific voltage by extrapolating it. However, even if the starting torque characteristic curve G2 is not linear, it is still possible to calculate the starting torque for an input voltage higher than the measurement point by extrapolating the starting torque characteristic curve G2, although the accuracy will be slightly reduced.
[0056] The starting torque characteristic curve G2 in Figure 16 is the characteristic measured without connecting the drive circuit 120 to the motor under test 100, and shows the starting torque characteristic of the motor under test 100 alone. In this way, in the second embodiment, the starting torque characteristic of the motor under test 100 alone can be accurately measured without being affected by the characteristics of the drive circuit 120.
[0057] C. Third Embodiment: Figure 17 is a block diagram showing the configuration of a motor test system for measuring the starting torque of the motor under test 100 in the third embodiment. The only difference between the system configuration of the third embodiment and the second embodiment is the addition of a drive circuit 120 between the constant current power supply 140 and the motor under test 100; the other configurations are the same as in the second embodiment.
[0058] Figure 18 is a flowchart of the starting torque measurement of the motor 100 under test in the third embodiment. This procedure is the same as the procedure in the second embodiment shown in Figure 15, with step S110 replaced by steps S210 and S220, and the other steps are the same as in the second embodiment.
[0059] In step S210, one of the M-phase coils of the motor under test 100 is selected as a specific phase coil, and the PWM duty cycle of the drive circuit 120 for the specific phase coil is set to 100%. In step S220, while maintaining the state of step S210, a DC current of a constant current value Is (=Ii) is input to the specific phase coil, and the input voltage Ei to the drive circuit 120 is measured. This input voltage Ei corresponds to the sum of the voltages generated in the drive circuit 120 and the specific phase coil. The processing from step S120 onward is the same as in the second embodiment described in Figure 15, so the explanation is omitted.
[0060] Figure 19 is a graph showing the starting torque characteristics of the motor under test 100 obtained in the third embodiment. Multiple black circles indicate measurement points, and the dotted line shows the starting torque characteristic curve G3 created from multiple measurement points. This starting torque characteristic curve G3 is a straight line, similar to the starting torque characteristic curve G2 of the second embodiment shown in Figure 16, but it may also be an approximate curve other than a straight line. In the third embodiment as well, in the process shown in Figure 18, it is preferable to set the input voltage Ei to be 1 / 10 or less of the rated voltage of the motor under test 100.
[0061] The starting torque characteristic curve G3 in Figure 19 is a characteristic measured with the drive circuit 120 connected to the motor under test 100, and shows the starting torque characteristics of the drive system composed of the motor under test 100 and the drive circuit 120. In this way, in the third embodiment, the starting torque characteristics of the motor under test 100 can be accurately measured, including the influence of the characteristics of the drive circuit 120. Furthermore, by obtaining the starting torque characteristic curve G2 of the motor under test 100 alone according to the method of the second embodiment, and obtaining the starting torque characteristic curve G3 of the drive system including the motor under test 100 and the drive circuit 120 according to the method of the third embodiment, it is possible to determine the superiority or inferiority of the performance of the drive circuit 120 from the difference between them.
[0062] D. Fourth Embodiment: Figure 20 is a block diagram showing the configuration of a motor test system for measuring the starting torque of the motor under test 100 in the fourth embodiment. The only differences between the system configuration of the fourth embodiment and the third embodiment are three points: the use of a constant voltage power supply 130 in addition to the constant current power supply 140; the addition of a switch circuit 170 that switches between the two and connects to the drive circuit 120; and the provision of an electromagnetic brake 236 and its drive circuit 237 for braking the rotating shaft of the electric brake 230. The other configurations are the same as in the third embodiment.
[0063] Figure 21 is a flowchart of the starting torque measurement of the motor under test 100 in the fourth embodiment. In step S310, the motor under test 100 is rotated by the electric brake 230 while a constant DC current is input to a specific phase coil. In step S310, the constant current power supply 140 is connected to the drive circuit 120 via the switch circuit 170, and the DC current from the constant current power supply 140 is input to the specific phase coil via the drive circuit 120. Alternatively, the DC current from the constant current power supply 140 may be input to the motor under test 100 without going through the drive circuit 120. The operation of step S310 is substantially the same as the operation of step S120 in the second embodiment described in Figure 15. In step S310, the change in torque accompanying the rotation is measured by the torque meter 220, and the maximum value of the torque accompanying the rotation is determined.
[0064] In step S320, the rotating shaft is fixed at the rotational position where the torque is at its maximum value, and the DC current input is stopped. The rotating shaft is fixed by operating the electromagnetic brake 236, which is connected to the rotating shaft of the electric brake 230, via the drive circuit 237. Normally, the electromagnetic brake 236 is kept in a non-braking state, and the rotating shaft of the electric brake 230 is not fixed. Alternatively, a braking device other than the electromagnetic brake 236 may be used to fix the rotating shaft of the motor under test 100 at the rotational position where the torque is at its maximum value.
[0065] In step S330, the torque meter 220 is set to peak hold mode, and the power supply to the motor under test 100 is switched from the constant current power supply 140 to the constant voltage power supply 130. Peak hold mode is a mode that holds the peak value of the measured torque.
[0066] In step S340, a rectangular pulse voltage is applied to a specific phase coil of the motor 100 under test to measure the peak torque.
[0067] Figure 22 is an explanatory diagram showing the state in step S340 where a rectangular pulse voltage Vp is applied to a specific phase coil. The drive circuit 120 includes an H-bridge circuit composed of four transistors 121 to 124 that drive the A-phase coil 101. Control signals Sd1 to Sd4 are input to the gate electrodes of the four transistors 121 to 124, respectively. When the A-phase coil 101 is used as a specific phase coil, by setting the control signals Sd1 and Sd4 of two transistors 121 and 124 to the ON level and the control signals Sd2 and Sd3 of the other two transistors 122 and 123 to the OFF level, it is possible to apply a rectangular pulse voltage Vp to the A-phase coil 101. The voltage level Es of the rectangular pulse voltage Vp is approximately the same as the input voltage Ei supplied from the constant voltage power supply 130. In this way, in the process of step S350, the peak torque generated by the motor under test 100 can be measured when a specific input voltage Ei is supplied to the specific phase coil of the motor under test 100. This peak torque corresponds to the starting torque.
[0068] The on-period To of the rectangular pulse voltage Vp can be arbitrarily set by the test control device 300. However, if the length of the on-period To is excessively short, it may not be possible to measure the starting torque properly, so it is preferable to set the on-period To to 100 μs or more. On the other hand, if the length of the on-period To is excessively long, it may cause excessive heat generation in the specific phase coil, so it is preferable to set the on-period To to 20 ms or less, and more preferably to 10 ms or less.
[0069] When measuring the peak torque in step S340, for example, the initial value of the on-period To of the rectangular pulse voltage Vp is set to a sufficiently small value, and the peak torque value is measured with the torque meter 220 at each length of the on-period To while gradually increasing the on-period To. The torque at the point when the peak value no longer substantially increases even when the on-period To is increased can then be determined as the "peak torque". For example, the maximum value of the moving average of the peak values over a certain number of times may also be determined as the "peak torque".
[0070] In step S350, it is determined whether or not to perform the processes described in steps S310 to S340 using the coils of other phases. If the processes in steps S310 to S340 have not been completed for all of the M-phase coils of the motor under test 100, the process returns from step S350 to step S310, the specific phase coil is changed, and steps S310 to S340 are executed again. Once the processes in steps S310 to S340 have been completed for all of the M-phase coils, the process proceeds to step S360.
[0071] In step S360, the starting torque of the motor under test 100 is determined from the M peak torques obtained for the M-phase coil of the motor under test 100. For example, the average value, maximum value, or minimum value of the M peak torques can be determined as the starting torque.
[0072] It is not necessary to perform steps S310 to S340 for all M-phase coils; steps S310 to S140 may be performed for at least one phase coil. For example, if steps S310 to S340 are performed for only one phase coil, the peak torque obtained for that coil will be directly determined as the starting torque.
[0073] In the fourth embodiment, it is possible to measure the starting torque when a constant input voltage Ei is applied to a specific phase coil. This input voltage Ei can be set to a higher voltage value than the input voltage generated in response to the DC current in the second and third embodiments, and can be set to a value equal to the rated voltage of the motor 100 under test. Furthermore, since a rectangular pulse voltage Vp is used when measuring the starting torque, it is possible to measure the starting torque of the motor 100 under test without causing excessive heat generation in the specific phase coil.
[0074] This disclosure is not limited to the embodiments, models, and modifications described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments, models, and modifications corresponding to the technical features in each form described in the Summary of the Disclosure section can be replaced or combined as appropriate to solve some or all of the above-described problems or to 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.
[0075] (1) According to one embodiment of the present disclosure, a motor test apparatus is provided for use in testing the characteristics of a motor under test. The motor test apparatus comprises a first coupling connected to the rotating shaft of the motor under test, a first rotating shaft connected to the first coupling, and a second rotating shaft, and a torque meter for measuring the torque between the first rotating shaft and the second rotating shaft, a second coupling connected to the second rotating shaft of the torque meter, and an electric brake having a coreless motor structure and a rotating shaft connected to the second coupling, an AC / DC converter unit electrically connected to the coil of the electric brake and converting the AC induced voltage generated in the coil into a DC voltage, and a DC load unit electrically connected to the AC / DC converter unit and consuming power from the DC voltage. The DC load unit has a configuration in which a variable current control unit for variably adjusting the DC current value and a resistor are arranged in series between two input terminals to which the DC voltage is applied. This motor testing apparatus uses an electric brake with a coreless motor structure, converts the AC induced voltage of the electric brake generated by the rotation of the motor under test into a DC voltage, and consumes that power in the DC load section. This allows testing of the transient response characteristics of the motor under test to sudden transient changes.
[0076] (2) A method for measuring the characteristics of a motor under test using the motor testing apparatus described above, comprising the steps of: connecting the motor under test to the motor testing apparatus and measuring the TN characteristics of the motor under test; and determining a corrected TN characteristic for the motor under test by performing a correction by adding the loss torque of a pre-created loss TN characteristic that shows the relationship between the loss torque corresponding to the loss of the motor testing apparatus when the motor under test is not connected and the rotational speed, to the torque of the TN characteristic of the motor under test. This method allows for the determination of the corrected TN characteristics of the motor under test alone, excluding the loss torque component corresponding to the losses of the motor test equipment.
[0077] (3) A method for measuring the starting torque of a motor under test using the motor testing apparatus described above, comprising: (a) when M is an integer of 2 or more, with the motor under test having an M-phase coil connected to the motor testing apparatus, inputting a DC current of a constant value to one specific phase coil of the M-phase coil and measuring the input voltage of the specific phase coil; (b) with the DC current of a constant value input to the specific phase coil, applying rotation to the motor under test by the electric brake and determining the maximum torque of the torque change accompanying the rotation; (c) changing the constant value and performing steps (a) to (b) multiple times to determine multiple maximum torques corresponding to multiple input voltages with respect to the specific phase coil; (d) using the multiple maximum torques corresponding to the multiple input voltages to create a starting torque characteristic curve showing the change in starting torque corresponding to the multiple input voltages; and (e) extrapolating the starting torque characteristic curve to calculate the starting torque for a specific voltage higher than the multiple input voltages. This method allows for accurate measurement of the starting torque of the motor under test alone, without being affected by the drive circuit.
[0078] (4) A method for measuring the starting torque of the motor under test using the motor test apparatus described above, comprising: (a) When M is an integer of 2 or more, connecting the motor under test having an M-phase coil to the motor test apparatus, setting the PWM duty cycle of the drive circuit of the motor under test with respect to one specific phase coil of the M-phase coil to 100%, inputting a DC current of a constant current value to the specific phase coil via the drive circuit, and measuring the input voltage of the drive circuit; and (b) With the DC current of a constant current value input to the specific phase coil, the motor under test is tested using the electric brake. The process includes: (c) applying rotation to a motor and determining the maximum torque associated with the torque change due to the rotation; (d) changing the constant current value and performing steps (a) to (b) multiple times to determine multiple maximum torques for a specific phase coil corresponding to multiple input voltages; (e) using the multiple maximum torques corresponding to the multiple input voltages to create a starting torque characteristic curve showing the change in starting torque corresponding to the multiple input voltages; and (f) extrapolating the starting torque characteristic curve to calculate the starting torque for a specific voltage higher than the multiple input voltages. This method allows for the accurate measurement of the starting torque related to the drive system, including the motor under test and the drive circuit.
[0079] (5) The above method, wherein step (d) may include a step of sequentially selecting one phase coil of the M phase coil as the specific phase coil and performing steps (a) to (c), and for each of the plurality of input voltages, selecting the average value, maximum value, or minimum value of the M maximum torques for the M phase coil as the starting torque. This method allows for a more accurate determination of the starting torque.
[0080] (6) A method for measuring the starting torque of a motor under test using the motor testing apparatus described above, comprising: (a) when M is an integer of 2 or more, connecting the motor under test having an M-phase coil to the motor testing apparatus, inputting a DC current of a constant value to one specific phase coil of the M-phase coil via the drive circuit of the motor under test, applying rotation to the motor under test with the electric brake, and measuring the torque change associated with the rotation; (b) stopping the rotation of the electric brake at the rotation angle at which the maximum torque value of the torque change occurs and maintaining the rotation angle; (c) while maintaining the rotation angle of the electric brake, applying a rectangular pulse voltage of a specific voltage value to the specific phase coil of the motor under test via the drive circuit to measure the peak torque; and (d) determining the starting torque of the motor under test using the peak torque. This method allows for the accurate measurement of the starting torque of the motor under test for a specific voltage value.
[0081] (7) The above method, wherein step (d) may include a step of sequentially selecting one phase coil of the M phase coil as the specific phase coil and performing steps (a) to (c), and selecting the average value, maximum value, or minimum value of the M peak torques for the M phase coil as the starting torque. This method allows for a more accurate determination of the starting torque. [Explanation of Symbols]
[0082] 100…Motor under test, 101…A-phase coil, 104…Magnetic sensor, 110…Rotating shaft, 120…Drive circuit, 121~124…Transistor, 130…Constant voltage power supply, 140…Constant current power supply, 150…Input ammeter, 151…Phase ammeter, 160…Input voltmeter, 161…Phase voltmeter, 170…Switch circuit, 200…Motor test device, 211…First coupling, 212…Second coupling, 220…Torque meter, 221…First rotating shaft, 222…Second rotating shaft, 230…Electric brake, 231A…A-phase coil, 231B…B-phase coil, 232…Rotating shaft, 234…Magnetic sensor, 234A… Phase A magnetic sensor, 234B…Phase B magnetic sensor, 235…Drive circuit, 236…Electromagnetic brake, 237…Drive circuit, 240…AC / DC conversion section, 241A…Full-wave rectifier circuit, 241B…Full-wave rectifier circuit, 242…Smoothing capacitor, 243A…Polarity separation circuit, 243B…Polarity separation circuit, 246p, 246n…Output terminals, 250…DC load section, 251p, 251n…Input terminals, 252…Variable current control section, 253…Transistor, 254…Operational amplifier, 255…Current command section, 256…Resistor, 260…Power meter, 270…Test connection structure, 300…Test control device, 310…Memory
Claims
1. A motor testing device used for characteristic testing of a motor under test, A first coupling connected to the rotating shaft of the motor under test, A torque meter having a first rotating shaft connected to the first coupling and a second rotating shaft, and measuring the torque between the first rotating shaft and the second rotating shaft, A second coupling connected to the second rotating shaft of the torque meter, An electric brake having a rotating shaft connected to the second coupling, the electric brake having a coreless motor structure, An AC / DC converter is electrically connected to the coil of the electric brake and converts the AC induced voltage generated in the coil into a DC voltage. A DC load unit is electrically connected to the AC / DC conversion unit and consumes power due to the DC voltage, Equipped with, The DC load unit has a configuration in which a variable current control unit that adjusts the DC current value and a resistor are arranged in series between the two input terminals to which the DC voltage is applied. Motor testing equipment.
2. A method for measuring the characteristics of a motor under test using the motor testing apparatus described in claim 1, The steps include: connecting the motor under test to the motor testing device and measuring the T-N characteristics of the motor under test; The process of determining a corrected T-N characteristic for the motor under test by performing a correction by adding the loss torque of a pre-created loss T-N characteristic, which shows the relationship between the loss torque corresponding to the loss of the motor test device when the motor under test is not connected and the rotational speed, to the torque of the T-N characteristic of the motor under test. A method that includes this.
3. A method for measuring the starting torque of a motor under test using the motor testing apparatus described in claim 1, (a) When M is an integer of 2 or more, the motor under test having an M-phase coil is connected to the motor test device, and a DC current of a constant value is input to one of the M-phase coils, and the input voltage of the specific phase coil is measured. (b) With the DC current of the constant current value input to the specific phase coil, rotation is applied to the motor under test by the electric brake, and the maximum torque of the torque change associated with the rotation is determined. (c) A step of determining a plurality of maximum torques corresponding to a plurality of input voltages for the specific phase coil by changing the constant current value and performing steps (a) to (b) a plurality of times, (d) A step of creating a starting torque characteristic curve that shows the change in starting torque according to the multiple input voltages, using the multiple maximum torques according to the multiple input voltages, (e) A step of calculating the starting torque for a specific voltage higher than the plurality of input voltages by extrapolating the starting torque characteristic curve, Methods that include...
4. A method for measuring the starting torque of a motor under test using the motor testing apparatus described in claim 1, (a) When M is an integer of 2 or more, connect the motor under test having an M-phase coil to the motor test device, set the PWM duty cycle of the drive circuit of the motor under test with respect to one specific phase coil of the M-phase coil to 100%, input a DC current of a constant value to the specific phase coil via the drive circuit, and measure the input voltage of the drive circuit. (b) With the DC current of the constant current value input to the specific phase coil, rotation is applied to the motor under test by the electric brake, and the maximum torque of the torque change associated with the rotation is determined. (c) A step of determining a plurality of maximum torques corresponding to a plurality of input voltages for the specific phase coil by changing the constant current value and performing steps (a) to (b) a plurality of times, (d) A step of creating a starting torque characteristic curve that shows the change in starting torque according to the multiple input voltages, using the multiple maximum torques according to the multiple input voltages, (e) A step of calculating the starting torque for a specific voltage higher than the plurality of input voltages by extrapolating the starting torque characteristic curve, Methods that include...
5. The method according to claim 3 or 4, The aforementioned step (d) is, Steps (a) to (c) are performed by sequentially selecting one phase coil of the M-phase coil as the specific phase coil, and for each of the plurality of input voltages, the average value, maximum value, or minimum value of the M maximum torques for the M-phase coil is selected as the starting torque. Methods that include...
6. A method for measuring the starting torque of a motor under test using the motor testing apparatus described in claim 1, (a) When M is an integer of 2 or more, the motor under test having an M-phase coil is connected to the motor testing device, a constant DC current is input to one specific phase coil of the M-phase coil via the drive circuit of the motor under test, and rotation is applied to the motor under test by the electric brake, and the torque change associated with the rotation is measured. (b) A step of stopping the rotation of the electric brake at the rotation angle at which the maximum torque value among the torque changes occurs and maintaining the rotation angle, (c) While maintaining the rotation angle of the electric brake, a step of measuring the peak torque by applying a rectangular pulse voltage of a specific voltage value to the specific phase coil of the motor under test via the drive circuit, (d) A step of determining the starting torque of the motor under test using the peak torque, A method that includes this.
7. The method according to claim 6, The aforementioned step (d) is, Steps (a) to (c) are performed by sequentially selecting one phase coil of the M-phase coil as the specific phase coil, and the average value, maximum value, or minimum value of the M peak torques for the M-phase coil is selected as the starting torque. Methods that include...