Motor drive system and motor drive method

Abstract

A power conversion device according to one embodiment of the present invention generates a detection result for outputting a position from a position sensor with respect to the position of a motor in accordance with a first period. The position sensor updates a delay time from a first timing at which a result of detecting the position of the motor is detected to a second timing at which information on the position of the motor is acquired in accordance with a second cycle in a control cycle of the motor. The power conversion device is provided with a compensation amount adjustment unit and a control unit. The compensation amount adjustment unit counts the time from the first timing to the second timing, and generates a compensation value for compensating the position information on the basis of the result of the counting. The control unit controls the position of the motor on the basis of the position information of the result of the compensation and the position command information of the motor.

Description

Technical Field

[0001] Embodiments of the present invention relate to a motor drive system and a motor drive method. Background Art

[0002] The motor drive system uses a position sensor to detect the position of the motor and control the position of the motor. Generally speaking, the motor control cycle is set longer than the cycle in which the position sensor outputs and updates the position detection result. However, due to the delay time from the output of the position sensor's position detection result to the acquisition of its detection result in each control cycle, it sometimes affects the responsiveness and stability of the motor control. If the size of the delay time is irregular, it is difficult to reduce its impact. In the control of the motor, it is hoped to reduce the impact of this delay time.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2021 / 149187 Pamphlet Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] An object of the present invention is to provide a motor drive system and a motor drive method capable of reducing the influence of a delay time from the timing when a position sensor outputs a detection result of a motor position to the timing when the detection result is updated in accordance with a control cycle.

[0008] Means for solving problems

[0009] A motor drive system according to one embodiment of the present invention generates a delay time from a first timing at which a position sensor outputs a detection result of a position of a motor in a first cycle and updates the detection result of the position of the motor by the position sensor to a second timing at which information on the position of the motor is obtained in a second cycle during a control cycle of the motor. The motor drive system includes a compensation amount adjustment unit and a control unit. The compensation amount adjustment unit counts the time from the first timing to the second timing, and generates a compensation value for compensating the position information based on the counted result. The control unit implements position control on the motor based on the position information of the compensation result and the information of the position command of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A It is a diagram showing the configuration of the motor drive system according to the first embodiment.

[0011] Figure 1B This is a diagram showing the configuration of a computing unit according to the first embodiment.

[0012] Figure 1C It is a diagram showing the configuration of the compensation amount adjustment unit according to the first embodiment.

[0013] Figure 2 It is a diagram for explaining the position compensation amount adjustment according to the first embodiment.

[0014] Figure 3 It is a diagram for explaining adjustment of the compensation amount of the position according to the modification of the first embodiment.

[0015] Figure 4A It is a configuration diagram of a motor drive system according to a second embodiment.

[0016] Figure 4B It is a diagram showing the configuration of a computing unit according to the second embodiment.

[0017] Figure 4C It is a diagram showing the configuration of a compensation amount adjustment unit according to the second embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, the motor drive system and the motor drive method of the embodiment will be described with reference to the accompanying drawings. In addition, in the following description, the same reference numerals are marked for the components having the same or similar functions. And, the repeated description of these components is sometimes omitted. In addition, electrical connection is sometimes referred to as "connection". In the case of "equal size" shown in the following description, the case of being approximately equal is also included.

[0019] Figure 1A It is a diagram showing the configuration of the motor drive system 1 according to the first embodiment.

[0020] Figure 1B It is a diagram showing the configuration of the calculation unit 31 according to the first embodiment.

[0021] Figure 1C It is a diagram showing the configuration of the compensation amount adjustment unit 51 according to the first embodiment.

[0022] The motor drive system 1 includes, for example, a motor 2 , a position sensor 3 , and a power conversion device 10 .

[0023] Motor 2( Figure 1A ) is, for example, an AC motor having a plurality of windings. The windings of each phase of the AC are connected to the output of the power conversion device 10 described later. The power conversion device 10 supplies AC power to the motor 2. The motor 2 rotates by the AC power. For example, a position sensor 3 ( Figure 1AThe record in is PS. ) The shaft of the position sensor 3 rotates in conjunction with the rotation of the shaft of the motor 2.

[0024] The position sensor 3 detects the absolute position of the shaft of the motor 2. The position sensor 3 is an example of an absolute encoder. The position sensor 3 calculates and outputs an absolute phase.

[0025] The power conversion device 10 is connected to the motor 2 and the position sensor 3. The power conversion device 10 controls the motor 2 so that the actual position of the shaft of the motor 2 detected by the position sensor 3 matches the position corresponding to the position command value supplied separately.

[0026] like Figure 1B As shown, the position sensor 3 includes a position sensor body and a computing unit 31 ( Figure 1A The record in is FPGA: Field-Programmable Gate Array. ).

[0027] The calculation unit 31 of the position sensor 3 includes, for example, a z position detection unit 311 , an ab position detection unit 312 , an update cycle generation unit 313 , a position information calculation unit 314 , and an output unit 316 .

[0028] The z position detection 311 of the position sensor 3 detects an absolute position through the position sensor body, and outputs information of the absolute position accompanying the detection.

[0029] The ab position detection 312 of the position sensor 3 detects the relative position by the position sensor body, and outputs the information of the relative position accompanying the detection.

[0030] The update cycle generation unit 313 generates a cycle for periodically updating the position information detected by the position sensor 3 and a timing signal for outputting the position information.

[0031] The position information calculation unit 314 periodically generates the current position information Qr using the timing signal supplied from the update cycle generation unit 313 .

[0032] The output unit 316 has an interface for communicating with an external device. The output unit 316 outputs the position information Qr by serial communication. The type of the signal output by the output unit 316 may be an optical signal or an electrical signal.

[0033] The power conversion device 10 includes an inverter 4 and a controller 5 .

[0034] The inverter 4 is an example of a power converter in which a plurality of semiconductor switches are formed in a bridge type. For example, the inverter 4 converts DC power supplied from a DC power source (not shown) into AC power, and supplies the AC power to the motor 2 to drive the motor 2 .

[0035] The controller 5 is a control device for the inverter 4 that drives the motor 2 .

[0036] The controller 5 includes, for example, a compensation amount adjustment unit 51 ( Figure 1A The record in is FPGA. ), and CPU52.

[0037] The CPU 52 is, for example, a computer including a processor that executes a predetermined calculation process by executing a program, a semiconductor memory, a drive circuit of the inverter 4, a clock, etc. The CPU 52 is connected to the compensation amount adjustment unit 51 as its peripheral circuit. The CPU 52 includes: a position control unit that obtains the position information generated by the compensation amount adjustment unit 51 and performs position control based on the position information; a current control unit that adjusts the flowing current based on the result of the position control; and a PWM control unit that implements PWM control for supplying power based on the result of the current control from the inverter 4, etc. The various processes related to the position control, current control, PWM control, etc. of the motor 2 performed by the CPU 52 can also be applied to general methods.

[0038] Reference Figure 1C An example of the compensation amount adjustment unit 51 of the controller 5 will be described.

[0039] The compensation amount adjustment unit 51 includes, for example, an interface 511 , a differential position information generation unit 512 , a control cycle generation unit 513 , a delay time information calculation unit 514 , a compensation amount calculation unit 515 , and a compensation calculation unit 516 .

[0040] The interface 511 includes a receiving circuit for receiving a signal from the position sensor 3. The signal from the position sensor 3 is, for example, a serial communication signal, and includes position information that is periodically transmitted. The interface 511 extracts the periodically transmitted position information Qr from the signal received from the position sensor 3 and outputs it. The position information Qr is equivalent to the position information output by the position sensor 3.

[0041] The differential position information generating unit 512 derives the amount of change ΔQr of the position caused by the update of the position information Qr based on the position information Qr outputted from the interface 511. The differential position information generating unit 512 calculates the amount of change ΔQr of the position according to the timing at which the position sensor 3 outputs the position information, in other words, the timing at which the position information is received from the position sensor 3. In addition, the differential position information generating unit 512 outputs the amount of change ΔQr of the position as information changing over time.

[0042] The control cycle generation unit 513 is a timer that specifies the cycle (control cycle) of the control operation of the power conversion device 10. The control cycle generation unit 513 has a counter that can count the time width of the control cycle. The control cycle generation unit 513 receives the clock CLK of the cycle Tc generated in the controller 5, counts the clock CLK through its counter, and outputs the count value CNT of the counting result. When the control cycle generation unit 513 reaches the specified upper limit value, the count value CNT is cleared to zero and the counting is restarted. The count value CNT output by the control cycle generation unit 513 is associated with the phase in the control cycle.

[0043] In synchronization with the reception timing of the position information Qr, the delay time information calculation unit 514 samples and holds the count value CNT output by the control cycle generation unit 513. The delay time information calculation unit 514 calculates the delay time Td by subtracting the count value CNT sampled and held from the value of the control cycle Ti.

[0044] The compensation amount calculation unit 515 calculates the compensation amount Qc using the position change amount ΔQr and the delay time Td. This will be described later.

[0045] The compensation calculation unit 516 generates position information Q based on the position information Qr output from the interface 511 and the compensation amount Qc calculated by the compensation amount calculation unit 515. The position information Q is information compensated for the influence of the delay time Td.

[0046] The absolute phase information output by the position sensor 3 is periodically transmitted to the power conversion device 10 configured as described above through serial communication. The power conversion device 10 periodically receives the detection result of its position and holds it until the next reception. When the power conversion device 10 receives the detection result of the next position, it updates the detection result held so far and repeats the operation.

[0047] However, there is a case where the sampling time of the control cycle of the motor 2 arrives while the position detection result is being held. In this case, the power conversion device 10 uses the held position detection result for position control of the motor 2. The sampling time of the control cycle refers to the timing for acquiring various information indicating the position and other conditions of the motor 2 in order to control the motor 2.

[0048] In the comparative example, as described above, the detection result is updated periodically and is used for the position control with a delay from the time when the phase indicated by the absolute phase is detected. A delay time Td occurs from the update of the detection result to the sampling timing for use in the position control.

[0049] The power conversion device 10 of the present embodiment compensates for the delay amount generated in the control cycle. This will be described in detail.

[0050] Reference Figure 2 The position compensation amount adjustment according to the first embodiment will be described.

[0051] Figure 2 It is a diagram for explaining the position compensation amount adjustment according to the first embodiment.

[0052] exist Figure 2 The timing chart shown shows the phase of the control cycle, the control cycle of the power conversion device, and the update cycle of the position information in order from the upper stage. The horizontal axis of the timing chart shows the passage of time.

[0053] Figure 2 The "Phase of Control Cycle" at the top shows a continuous triangular wave. The amplitude of each triangular wave indicates the phase of the control cycle. The amplitude of the triangular wave is the counting result of the control cycle generator 513. Therefore, the triangular wave that appears to change continuously strictly changes in value in a step-like manner. In this way, by setting the quantization level of the output of the control cycle generator 513 to be relatively dense, it can be regarded as a continuous change.

[0054] Figure 2 The second row from the top shows the duration and phase of the control cycle for performing various control operations of the power conversion device 10. In this figure, four consecutive control cycles identified by (N-1), (N), (N+1), and (N+2) as identification indicators are depicted.

[0055] Figure 2 The third section from the top shows the period and phase of the cycle in which the position sensor 3 outputs the detection result of the absolute phase. In this figure, 11 consecutive update cycles are depicted, which are identified using (n-3), (n-2), (n-1), (n), (n+1), (n+2), (n+3), (n+4), (n+5), (n+6), and (n+7) as identification indicators.

[0056] The detection results obtained in each update cycle are also shown in the 3rd segment. For example, the detection results obtained in the update cycles of (n-3), (n-2), (n-1), and (n) are respectively recorded as Qr(n-3), Qr(n-2), Qr(n-1), and Qr(n).

[0057] However, the sampling timing of the next control cycle, ie, the control cycle (N), is generated during the update cycle (n).

[0058] The time from the start timing (first timing) of the update cycle (n) to the sampling timing (second timing) of the control cycle (N) is called the delay time Td(N). The delay time Td(N) corresponding to the control cycle (N) is defined by the following formula (1).

[0059] Td(N)=Tc*(Ti / Tc-CNT(N)) (1)

[0060] "CNT(N)" in the above formula (1) is the count value of the counter at the start timing of the period of the update cycle (n).

[0061] As described above, the sampling timing of the control cycle (N+1) is generated during the update cycle (n+3). The time (time difference) from the start timing of the update cycle (n+3) to the sampling timing of the control cycle (N+1) is called the delay time Td(N+1). The count value of the counter from the start timing of the update cycle (n+3) is recorded as CNT(N+1).

[0062] In addition, the sampling timing of the control cycle (N+2) is generated during the update cycle (n+7). The time (time difference) from the start timing of the update cycle (n+7) to the sampling timing of the control cycle (N+2) is called the delay time Td(N+2). The count value of the counter from the start timing of the update cycle (n+7) is recorded as CNT(N+2).

[0063] Hereinafter, the process of deriving the delay time Td for each control cycle by associating the sampling timing of each control cycle with the start timing of each control cycle will be described in more detail.

[0064] The power conversion device 10 is required to perform control calculations for driving the motor 2 according to a predetermined control cycle (referred to as control cycle Ti) based on the phase of the motor 2 at a predetermined time within the control cycle. For example, the predetermined time within the control cycle Ti corresponds to the start timing of the control cycle Ti.

[0065] In addition, it is assumed that the phase update period of the position sensor 3 and the communication period of the serial communication are not synchronized with respect to the control period Ti of the power conversion device 10. Under this condition, a delay occurs until the position information received by the power conversion device 10 is used for the calculation of the position control. Therefore, the position indicated by the position information received by the power conversion device 10 has an error due to the calculation performed in discrete time relative to the actual position at the time used for the calculation of the position control.

[0066] The phase update period of the position sensor 3 is synonymous with the update period of the position information of the position detected by the position sensor 3 .

[0067] Adjustment of the control period Ti of the power conversion device 10:

[0068] For example, the control period Ti of the power conversion device 10 is determined according to the use of the applied system. In this case, if necessary, its control period Ti can also be changed relative to the standard value within its allowable range.

[0069] The position sensor 3 of the embodiment is set such that the phase update period and the communication period of the serial communication with the power conversion device 10 are preset and cannot be changed. Therefore, even if the control period Ti of the power conversion device 10 is adjusted as described above according to the use of the applied system, the phase update period of the position sensor 3 and the communication period of the serial communication of the power conversion device 10 cannot be changed corresponding to the adjustment of the control period Ti of the power conversion device 10.

[0070] In the present embodiment, the power conversion device 10 compensates for this influence.

[0071] Relationship between the control period Ti of the power conversion device 10 and the phase update period of the position sensor 3:

[0072] Relative to the control period Ti of the power conversion device 10, the phase update period of the position sensor 3 and the communication period of the serial communication are fast enough.

[0073] In addition, to simplify the description, it is assumed that the position sensor 3 updates the phase and immediately sends it to the power conversion device 10, and its period is set as Ts. That is, as described above Figure 2 shown, the phase information is updated according to the update period Ts. The CPU of the power conversion device 10 performs control operations according to the period of the control period Ti. In this way, the relationship that the control period Ti is longer than the update period Ts (Ti > Ts) holds. In addition, when their magnitude relationship is reversed (Ti < Ts), it cannot function as the power conversion device 10. Therefore, the research and description in the case of omitting this condition are omitted.

[0074] Method for determining the phase during the control period Ti of the power conversion device 10:

[0075] The power conversion device 10 uses a period shorter than the update period Ts as the unit time and counts during the control period Ti of the power conversion device 10.

[0076] For example, the control cycle generator 513 of the power converter 10 has a counter that determines the value of the start time of the control cycle Ti to be 0 and counts up the clock CLK as time passes. The repetition period of the clock CLK is the period Tc.

[0077] For example, the control cycle generation unit 513 sets the count CNT to zero at the start of the next control cycle Ti. The control cycle generation unit 513 changes the count CNT between 0 and (Ti / Tc) by repeatedly counting from the start time of the control cycle Ti. The control cycle generation unit 513 always performs this counting so that the count CNT becomes information indicating the phase during the control cycle Ti. The control cycle generation unit 513 of the power conversion device 10 records the count CNT at the timing when the position information Qr is updated together with the position information Qr.

[0078] Derivation of delay time Td:

[0079] The differential position information generating unit 512 of the power conversion device 10 calculates the delay time Td indicating how much the transmission or reception of the last updated position information Qr is delayed using the last updated count CNT when the next control cycle Ti is about to start. The above formula (1) can be applied to this calculation. In addition, in the relationship shown in the formula (1), the influence of delay and fluctuation caused by serial communication is ignored.

[0080] Derivation of the compensation amount of delay time Td:

[0081] The differential position information generating unit 512 of the power converter 10 calculates the phase change ΔQr per update cycle Ts using the time-varying information of the position information Qr. The compensation amount calculating unit 515 calculates the compensation amount Qc of the position information Qr using the delay time Td and the phase change ΔQr per update cycle Ts.

[0082] The compensation calculation unit 516 generates the compensated position information Q based on the position information Qr and the compensation amount Qc calculated by the compensation amount calculation unit 515. For example, the compensation calculation unit 516 adds the compensation amount Qc to the phase Qr(n) for which the latest sample is performed, and calculates the corrected phase Q(N). This relationship is shown in the following equations (2-1) and (2-3).

[0083] ΔQr=Qr(n)-Qr(n-1)(2-1)

[0084] Qc=ΔQr*Td / Ts (2-2)

[0085] Q(N)=Qr(n)+Qc (2-3)

[0086] According to the above embodiment, the motor drive system 1 is a power conversion device that generates a delay time Td from a first timing to a second timing. At the first timing, the position sensor 3 outputs the detection result of the position of the motor 2 according to the first cycle, and at the second timing, the position information of the motor 2 is obtained according to the second cycle during the control cycle of the motor 2. The motor drive system 1 includes a compensation amount adjustment unit 51 and a CPU 52 (control unit). The compensation amount adjustment unit 51 counts the time (time difference) from the first timing to the second timing, and generates a compensation value for compensating the position information based on the result of the counting. The CPU 52 implements position control for the motor 2 based on the position information as the compensation result and the information of the position command of the motor 2. As a result, the influence of the delay time Td from the output of the detection result of the position of the motor 2 by the position sensor 3 to the update of the detection result according to the control cycle can be reduced.

[0087] (Modification of the first embodiment)

[0088] A modified example of the first embodiment is described. In the first embodiment, an example is described in which a change in the detection position between update cycles Ts is calculated based on the difference in the position information Qr of the detection result, and the change is taken as the change ΔQr. Instead of this, in this modified example, an example in which a moving average is used in the calculation of the change ΔQr is described.

[0089] Reference Figure 3 Adjustment of the compensation amount of the position according to a modification of the first embodiment will be described.

[0090] Figure 3 It is a diagram for explaining adjustment of the compensation amount of the position according to the modification of the first embodiment.

[0091] Figure 3 The information shown is consistent with the above Figure 2 This figure discloses numerical examples of each variable when specific conditions are set.

[0092] Modification example of derivation of the compensation amount of delay time Td:

[0093] In order to improve the accuracy of the compensation amount Qc, taking a moving average in the calculation of the change amount ΔQr is also a method. The following example is a simple moving average, but it is not limited to a specific moving average method, and the number of moves can also be arbitrary. The change amount ΔQr does not depend on the control cycle of the power conversion device 10, and the type of moving average method used and the length of the time window can also be determined in advance. This relationship is shown in the following formula (3).

[0094]

Number 1

[0095]

[0096] The variable m in the above formula (3) is a natural number representing the number of update cycles included in the time window that defines the range of the moving average processing. According to formula (3), the difference when the value of the variable k changes from 1 to m, that is, the total value of (Qr(n-(k-1))-Qr(nk)), is divided by m to derive the change ΔQr.

[0097] The following shows calculation results to which specific numerical values ​​are applied.

[0098] Control period of the power conversion device 10: Ti = 1000 μs

[0099] Phase update period: Ts = 300 μs

[0100] Counter period: Tc = 1 μs

[0101] Specifications of motor 2: 60Hz, two-pole AC motor, rated speed 3600rpm

[0102] Acceleration conditions: Assume acceleration from 0 to 100% speed within 1 second.

[0103] In the above case, as shown in the conversion formula below, the rotation speed is "21.6 degrees" per 1 millisecond.

[0104] In this case, it can be seen that the phase rotates by "6.48 degrees" within 300 μs (microseconds) of the phase update time Ts.

[0105] 3600rpm / 60s=60rps

[0106] 60rps / 1000ms=0.06r / ms

[0107] 360deg*0.06r / ms=21.6deg / ms

[0108] 21.6deg / ms*(300μs / 1000μs)=6.48deg / (300μs)

[0109] It is assumed that the position sensor 3 detects the following phase and notifies the power conversion device 10 of the detection phase.

[0110] Qr(n-3)=62deg

[0111] Qr(n-2)=68deg

[0112] Qr(n-1)=74.5deg

[0113] Qr(n)=80.5deg

[0114] A simple moving average with three elements in the time window (m=3) is used. The position change ΔQr in this case is calculated using the following formula. According to the calculation result, the position change ΔQr of the motor 2 rotates "6.17 degrees" within the 300 μs phase update time Ts.

[0115] ΔQr={(Qr(n)-Qr(n-1))+(Qr(n-1)-Qr(n-2))+(Qr(n-2)-Qr(n-3))} / 3

[0116] ={6+6.5+6} / 3

[0117] =6.17deg

[0118] On the other hand, as described above, if the counter CNT(N) becomes "830" when Qr(n) is "80.5 degrees", the delay time Td(N) becomes "170 μs" as shown in the following formula. Td(N) = Tc*(Ti / Tc-CNT(N))

[0119] =1μs*(1000μs / 1μs-830)

[0120] =170μs

[0121] When the numerical values ​​of the above variables are used for analysis, the magnitudes of Qc(N) and Q(N) become "3.496 degrees" and "84 degrees", respectively.

[0122] Qc(N)=ΔQr*Td(N) / Ts

[0123] =6.17deg*170μs / 300μs

[0124] =3.496deg

[0125] Q(N)=Qr(n)+Qc(N)

[0126] =80.5deg+3.496deg

[0127] =84deg

[0128] When the same conditions as above are applied to the comparative example, Q(N) becomes “80.5 degrees.” This value is the value of Qr(n) before compensation, and the influence of the delay time Td can be reduced by applying the present embodiment.

[0129] This modification also produces the same effects as those of the above-described embodiment. In addition, according to this modification, it is possible to improve the tolerance to accidental changes included in the position detection result.

[0130] As described above, if the variation in the transmission delay of the phase information is relatively small, the position sensor 3 that outputs the position information Qr can be used as long as it is implemented on the power conversion device 10 side.

[0131] The difference (change amount ΔQr) of the position information Qr can be regarded as a rate of change of the phase with respect to the update period Ts, and becomes a variable having the same dimension as the rotation speed and frequency of the motor 2 .

[0132] On the other hand, when the variation in the transmission delay of the phase information affects the control, the position sensor 3 may calculate the difference (the amount of change ΔQr) of the position information Qr.

[0133] (Second Embodiment)

[0134] The second embodiment is described. In the first embodiment, the following example is described: the position sensor 3 periodically outputs the position information Qr, and the power conversion device 10 calculates the difference (change ΔQr) of the position information Qr between the update cycles Ts. In this embodiment, the difference from the first embodiment is mainly used to describe the example in which the position sensor 3 periodically outputs the position information Qr and the difference (change ΔQr) of the position information Qr.

[0135] Figure 4A It is a diagram showing the configuration of a motor drive system 1A according to a second embodiment.

[0136] Figure 4B It is a diagram showing the configuration of a calculation unit 31A according to the second embodiment.

[0137] Figure 4C It is a diagram showing the configuration of a compensation amount adjustment unit 51A according to the second embodiment.

[0138] The motor drive system 1A includes, for example, a motor 2 , a position sensor 3A, and a power conversion device 10A.

[0139] The position sensor 3A detects the absolute position of the shaft of the motor 2 in the same manner as the position sensor 3. The position sensor 3A further derives the amount of change in the absolute position and outputs it. In addition, unless otherwise specified, the position sensor 3 of the first embodiment may be referred to as the position sensor 3A or the like to refer to the first embodiment.

[0140] like Figure 4BAs shown, the position sensor 3A includes a position sensor body and a computing unit 31A ( Figure 4A The record in is FPGA. ).

[0141] The calculation unit 31A of the position sensor 3A further includes a differential position information generation unit 315 in addition to the calculation unit 31 described above, and includes an output unit 316A in place of the output unit 316 .

[0142] The differential position information generating unit 315 derives the change amount ΔQr of the position represented by the position information Qr based on the position information Qr generated by the position information calculating unit 314. The differential position information generating unit 315 outputs the change amount ΔQr of the position in accordance with the timing at which the position sensor 3A outputs the position information Qr. Alternatively, the differential position information generating unit 315 may output the change amount ΔQr of the position as information changing over time.

[0143] The output unit 316A outputs the position information Qr in association with the position change amount ΔQr.

[0144] Such a position sensor 3A may generate time-varying information in which the position information Qr is associated with the amount of change ΔQr in the position.

[0145] The power conversion device 10A is connected to the electric motor 2 and the position sensor 3A.

[0146] In addition, unless otherwise specified, the power conversion device 10 of the first embodiment may be referred to as a power conversion device 10A.

[0147] The power conversion device 10A includes an inverter 4 and a controller 5A.

[0148] The controller 5A includes, for example, a compensation amount adjustment unit 51A ( Figure 4A The record in is FPGA. ), and CPU52.

[0149] Reference Figure 4C An example of the compensation amount adjustment unit 51A of the controller 5A will be described.

[0150] The correction amount adjustment unit 51A is different from the correction amount adjustment unit 51 in that it does not include the difference position information generation unit 512 and includes an interface 511A instead of the interface 511 .

[0151] The interface 511A extracts and outputs the position information Qr and the position change ΔQr periodically transmitted from the signal from the position sensor 3A. The position information Qr corresponds to the position information output by the position sensor 3. The position change ΔQr is supplied to the compensation amount calculation unit 515.

[0152] The compensation amount calculation unit 515 of this embodiment obtains the phase change ΔQr per update cycle Ts from the interface 511A. As in the first embodiment, the compensation amount calculation unit 515 calculates the compensation amount Qc of the position information Qr using the delay time Td and the phase change ΔQr per update cycle Ts.

[0153] In this manner, even when the calculation of the position change amount ΔQr is performed in the position sensor 3A, the same effects as those of the first embodiment can be achieved.

[0154] Furthermore, since the differential position information generating unit 315 is disposed in the position sensor 3A instead of the differential position information generating unit 512 , the position change amount ΔQr generated by the differential position information generating unit 315 is less susceptible to the influence of the variation in the transmission delay of the phase information.

[0155] (Third Embodiment)

[0156] A third embodiment will be described. In the first and second embodiments, the case where the position of the motor 2 is specified within the range of 0 to 360 degrees is described. Instead, in this embodiment, the case where the position of the motor 2 is specified within the range of -180 to +180 degrees is described.

[0157] When the position of the motor 2 is specified within the range of 0 to 360 degrees, the value representing the position returns to 0 degrees every time it rotates once. Therefore, when the previous value is simply subtracted from the current value of the position, the value of the change ΔQr may deviate significantly from the standard value.

[0158] In this case, for 360 degrees of rotation, the range of -180 degrees to +180 degrees and its polarity are used to determine the operation rules for conditional differentiation. In the case of the boundary where the polarity of the current value and the previous value of the position changes, the processing can be differentiated according to the conditional branch.

[0159] For example, when the polarity of the position difference changes from negative to positive, the following equation (4) holds true, and in this case, equation (5) is used.

[0160] Qr(n-1)<0∧Qr(n)>0 (4)

[0161] ΔQr=180°+Qr(n)-|Qr(n-1)| (5)

[0162] When the polarity of the position difference changes from positive to negative, the following equation (6) holds true, and in this case, equation (7) is used.

[0163] Qr(n-1)>0∧Qr(n)<0(6)

[0164] ΔQr=-(180°+|Qr(n)|-Qr(n-1))(7)

[0165] By using the calculation rules classified according to the conditions in this way, it is possible to suppress the value of the change amount ΔQr from deviating greatly from the standard value.

[0166] The above-mentioned embodiment can be combined with the above-mentioned first and second embodiments.

[0167] According to at least one embodiment described above, in a motor drive system 1 that generates a delay time from a first timing to a second timing, at a first timing, a detection result of the position of the motor is output from a position sensor according to a first cycle, and the detection result of the position of the motor 2 is updated by the position sensor, and at a second timing, information on the position of the motor 2 is obtained according to a second cycle during a control cycle of the motor. In this motor drive system 1, the influence of the delay time Td from when the position sensor outputs the detection result of the position of the motor to when the detection result is updated according to the control cycle can be reduced. In the above case, the motor drive system may include: a compensation amount adjustment unit that counts the time (time difference) from the first timing to the second timing, and generates a compensation value for compensating the position information based on the counted result; and a control unit that implements position control for the motor based on the position information as the compensation result and the information of the position command of the motor.

[0168] A part or all of the functional parts of the controller 5, 5A and the position sensor 3, 3A in the motor drive system 1, 1A of the embodiment described above may have, for example, a software functional part realized by executing a program (computer program, software component) stored in a storage unit (memory, etc.) of the computer by a computer processor (hardware processor). In addition, a part or all of the functional parts of the controller 5, 5A and the position sensor 3, 3A may be realized by hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array), or may be realized by a combination of software functional parts and hardware.

[0169] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the main purpose of the invention. For example, the structures of each embodiment can also be implemented in combination with each other and can be applied to the components that are omitted. These embodiments and their variations are included in the scope and main purpose of the invention, and are included in the invention recorded in the claims and their equivalents.

[0170] Description of Reference Numerals

[0171] 1.1A: Motor drive system

[0172] 2: Electric motor

[0173] 3.3A: Position sensor

[0174] 4: Inverter

[0175] 5.5A: Controller

[0176] 10, 10A: Power conversion device

[0177] 31, 31A: Operation unit

[0178] 51, 51A: compensation amount adjustment unit.

Claims

1. A motor drive system, generating a delay time from a first timing at which a position sensor outputs a detection result of a position of a motor in a first cycle and updates the detection result of the position of the motor by the position sensor to a second timing at which information on the position of the motor is obtained in a second cycle during a control cycle of the motor, wherein: have: a compensation amount adjustment unit that counts the time from the first timing to the second timing and generates a compensation value for compensating the position information based on a result of the counting; as well as The control unit performs position control on the motor based on information on the position as a result of the compensation and information on a position command of the motor.

2. The motor drive system according to claim 1, wherein: The compensation amount adjustment unit compensates the detection result according to the magnitude of the time difference from the first timing to the second timing.

3. The motor drive system according to claim 2, wherein: The compensation amount adjustment unit compensates the detection result using the magnitude of the time difference from the first timing to the second timing and information on the time-varying position of the motor at the first timing.

4. The motor drive system according to claim 2, wherein: The compensation amount adjustment unit is provided in any one of a motor drive system that drives the motor and the position sensor.

5. The motor drive system according to claim 3 or 4, wherein: The compensation amount adjustment unit generates the compensation value based on the counting result, compensates the detection result using the compensation value, and generates position information as a result of the compensation.

6. The motor drive system according to claim 1, wherein: The lengths of the first period and the second period are not equal.

7. The motor drive system according to claim 1, wherein: The compensation amount adjustment unit generates the compensation value based on the counting result, and generates information on the position as a result of the compensation using the compensation value and information on a change over time of the position as a result of the compensation.

8. A motor driving method, using a position sensor and a power conversion device, wherein the position sensor outputs a detection result of the position of the motor according to a first cycle, and the power conversion device generates a delay time from a first timing when the detection result of the position of the motor is updated by the position sensor to a second timing when information on the position of the motor is obtained according to a second cycle in a control cycle of the motor, the motor driving method comprising the following steps: counting the time from the first timing to the second timing, and generating a compensation value for compensating the position information based on the counting result, Position control of the motor is performed based on information of the position as a result of the compensation and information of the position command of the motor.

9. The motor driving method according to claim 8, wherein: The detection result is compensated according to the size of the time difference from the first timing to the second timing.

10. The motor driving method according to claim 9, wherein: The detection result is compensated using the magnitude of the time difference from the first timing to the second timing and information on the time-varying position of the motor at the first timing.

11. The motor driving method according to claim 9, wherein: A compensation value for compensating the position information is generated by either a power conversion device that drives the electric motor or the position sensor.

12. The motor driving method according to claim 10 or 11, wherein: The compensation value is generated based on the result of the counting, the detection result is compensated using the compensation value, and information on the position as a result of the compensation is generated.

13. The motor driving method according to claim 8, wherein: The lengths of the first period and the second period are not equal.

14. The motor driving method according to claim 8, wherein: The compensation value is generated based on the result of the counting, and information on the position as a result of the compensation is generated using the compensation value and information on the change over time of the position as a result of the compensation.

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