WO2020009062A1 - キャリア周波数設定方法、モータ駆動システムおよびキャリア周波数設定装置 - Google Patents
キャリア周波数設定方法、モータ駆動システムおよびキャリア周波数設定装置 Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 35
- 230000007423 decrease Effects 0.000 claims abstract description 18
- 239000004065 semiconductor Substances 0.000 claims description 43
- 230000008569 process Effects 0.000 claims description 12
- 238000009795 derivation Methods 0.000 claims description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 42
- 238000005259 measurement Methods 0.000 description 39
- 238000010586 diagram Methods 0.000 description 22
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 21
- 229910052802 copper Inorganic materials 0.000 description 21
- 239000010949 copper Substances 0.000 description 21
- 229910052742 iron Inorganic materials 0.000 description 21
- 238000012545 processing Methods 0.000 description 7
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- 229910000565 Non-oriented electrical steel Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/20—Estimation of torque
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/50—Vector control arrangements or methods not otherwise provided for in H02P21/00- H02P21/36
Definitions
- the present invention relates to a carrier frequency setting method, a motor drive system, and a carrier frequency setting device, and particularly suitable for driving a motor using an inverter.
- Priority is claimed on Japanese Patent Application No. 2018-126066 filed on July 2, 2018, the content of which is incorporated herein by reference.
- a PWM (Pulse Width Modulation) control type inverter is used as a power supply device for driving a motor of a train, a hybrid car, a home appliance, or the like.
- Such an inverter determines the width (time to turn on the pulse) of the pulse signal by comparing a carrier wave (for example, a triangular wave) with a voltage command signal, and switches a switching element (for example, IGBT (Insulated Gate Bipolar) in accordance with the generated pulse signal. Transistor)), the input DC power is converted into AC power having a frequency required for driving the motor and supplied to the motor by turning on / off the transistor.
- a carrier wave for example, a triangular wave
- IGBT Insulated Gate Bipolar
- Patent Literature 1 prepares table data in which a relationship between a carrier frequency (a frequency of a carrier wave) of PWM control that minimizes a total loss of the motor and the inverter and an electric angular frequency of the motor is prepared. It is disclosed that the inverter is driven at a carrier frequency of the PWM control corresponding to the detected value to drive the motor.
- a carrier frequency a frequency of a carrier wave
- Patent Documents 2 and 3 disclose setting a carrier frequency according to the number of rotations and torque of a motor. Specifically, in Patent Document 2, the carrier frequency is set to the lowest first frequency in the first region where the motor rotation speed is low and the motor torque is large. Further, in a second region where the rotation speed of the motor is higher than the rotation speed set in the first region and the torque of the motor is substantially the same as the torque set in the first region, The carrier frequency is set to a second frequency higher than the first frequency. Further, the rotational speed of the motor is higher than the rotational speed set in the first region and the second region, and the torque of the motor is higher than the torque set in the first region and the second region. In the third region where the second torque is low, the carrier frequency is set to the highest third frequency.
- Patent Document 3 a low carrier frequency is set in a region where the motor rotation speed is low and the motor torque is low, and the carrier frequency is set higher as the motor rotation speed increases. Patent Document 3 states that it is effective to lower the carrier frequency in the non-small torque region in the low rotation range.
- the present inventor investigated the relationship between the motor torque and the total loss of the motor loss and the inverter loss for each motor rotation speed. It has been found that setting the carrier frequency by the described method may not be preferable in terms of the total efficiency calculated from the total loss of the motor loss and the inverter loss.
- the present invention has been made in view of the above problems, and has as its object to drive a motor so that the total loss of the motor loss and the inverter loss is reduced.
- a carrier frequency setting method is a carrier frequency setting method for setting a carrier frequency in an inverter for driving a motor, wherein the loss of the inverter and the motor when the motor is driven using the inverter. Deriving the total loss which is the sum of the loss of the motor, the loss deriving step of making the torque generated in the motor, the rotation speed of the motor and the carrier frequency in the inverter different, and the loss deriving step.
- the optimal carrier frequency derived by the frequency deriving step Based on the number, the relationship between the motor torque and the optimum carrier frequency, a relationship deriving step for deriving for each motor speed, and the relationship derived for each motor speed by the relationship deriving step.
- a first example of the motor drive system of the present invention is a motor drive system including an inverter, a motor driven by receiving AC power supplied from the inverter, and a control device that controls an operation of the inverter.
- the inverter includes a switching element configured using a wide band gap semiconductor, and the control device determines a relationship between a motor torque derived for each rotation speed of the motor and a carrier frequency in the inverter.
- a second example of the motor drive system is a motor drive system including an inverter, a motor driven by receiving AC power from the inverter, and a control device that controls an operation of the inverter.
- the inverter has a switching element configured using a semiconductor other than a wide band gap semiconductor, the control device, the motor torque and the carrier frequency in the inverter derived for each rotation speed of the motor And a carrier frequency setting means for setting a carrier frequency of the inverter based on the relationship of the motor.
- the relationship between the motor torque and the carrier frequency derived for each rotation speed of the motor is related to the torque of the motor.
- the carrier frequencies have substantially the same value.
- a carrier frequency setting device of the present invention is a carrier frequency setting device for setting a carrier frequency of an inverter for driving a motor, wherein the carrier frequency setting device includes a torque of the motor, a loss of the inverter, and the motor.
- the inverter has a switching element configured by using a wide band gap semiconductor, as a relationship with the optimum carrier frequency that is the carrier frequency when the total loss that is the sum of In a range where the torque of the motor is greater than or equal to the torque of the motor corresponding to the carrier frequency at which the optimum carrier frequency is the lowest value, when the torque of the motor increases, the motor has a portion where the optimum carrier frequency increases, and the motor The torque at which the optimum carrier frequency has the lowest value A) In a range where the torque of the motor corresponding to the frequency is equal to or less than that, when the torque of the motor increases, a relationship further having a portion where the optimum carrier frequency decreases is derived for each rotation speed of the motor.
- the switching element is configured using a semiconductor other than the wide band gap semiconductor
- the relationship that the optimum carrier frequency is substantially constant is determined for each rotation speed of the motor. And setting the carrier frequency of the inverter based on the relationship between the torque of the motor and the optimum carrier frequency.
- the motor can be driven such that the total loss of the motor loss and the inverter loss is reduced.
- FIG. 3 is a diagram illustrating the first embodiment, and is a diagram illustrating, in a graph format, a relationship between a total efficiency ratio and a carrier frequency when a motor speed ratio is 1.00.
- FIG. 5 is a diagram illustrating the first embodiment, and is a first diagram illustrating, in a graph form, a relationship between a total loss ratio and a carrier frequency when a motor speed ratio is 1.00.
- FIG. 4 is a diagram illustrating the first embodiment, and is a second diagram illustrating, in a graph format, a relationship between a total loss ratio and a carrier frequency when a motor speed ratio is 1.00. It is a figure which shows 1st Embodiment and is a 1st figure which shows the measurement result of the loss at the time of the rotation speed ratio of a motor being 0.75 in a tabular form.
- FIG. 1st Embodiment It is a figure which shows 1st Embodiment and is a 2nd figure which shows the measurement result of the loss at the time of the rotation speed ratio of a motor being 0.75 in a tabular form. It is a figure which shows 1st Embodiment and is a 3rd figure which shows the measurement result of the loss at the time of the rotation speed ratio of a motor being 0.75 in a table form. It is a figure which shows 1st Embodiment, and is a figure which shows the relationship between the total efficiency ratio and carrier frequency when the rotation speed ratio of a motor is 0.75 in a graph form.
- FIG. 1st Embodiment It is a figure which shows 1st Embodiment and is a 2nd figure which shows the measurement result of the loss at the time of the rotation speed ratio of a motor being 0.75 in a tabular form. It is a figure which shows 1st Embodiment and is a 3rd figure which shows the measurement result of the loss at
- FIG. 6 is a diagram illustrating the first embodiment, and is a first diagram illustrating, in a graph form, a relationship between a total loss ratio and a carrier frequency when a rotation speed ratio of a motor is 0.75. It is a figure which shows 1st Embodiment and is a 2nd figure which shows the relationship between the total loss ratio and carrier frequency when the rotation speed ratio of a motor is 0.75 in a graph form. It is a figure which shows 1st Embodiment and is a 3rd figure which shows the relationship between the total loss ratio and carrier frequency when the rotation speed ratio of a motor is 0.75 in a graph form.
- FIG. 4 is a diagram illustrating the first embodiment, and is a first diagram illustrating, in a graph form, a relationship between an overall loss ratio and a carrier frequency when a motor speed ratio is 0.50. It is a figure which shows 1st Embodiment and is the 2nd figure which shows the relationship between the total loss ratio and carrier frequency when the rotation speed ratio of a motor is 0.50 in a graph form.
- FIG. 6 is a diagram illustrating the first embodiment, and is a first diagram illustrating, in a graph format, a relationship between a total loss ratio and a carrier frequency when a motor speed ratio is 0.25.
- FIG. 6 is a diagram illustrating the first embodiment, and is a second diagram illustrating, in a graph form, a relationship between the total loss ratio and the carrier frequency when the motor rotation speed ratio is 0.25. It is a figure which shows 1st Embodiment and is the 3rd figure which shows the relationship between the total loss ratio and carrier frequency when the rotation speed ratio of a motor is 0.25 in a graph form.
- 5 is a flowchart illustrating an example of a method for deriving a relationship between a torque of a motor M and a carrier frequency for each rotation speed of the motor M.
- FIG. 1 is a diagram illustrating an example of a schematic configuration of a motor drive system.
- the motor M is an IPMSM (Interior Permanent Magnet Synchronous Motor, a permanent magnet embedded type synchronous motor) having a permanent magnet built in a rotor.
- IPMSM Interior Permanent Magnet Synchronous Motor, a permanent magnet embedded type synchronous motor
- a motor drive system for driving such a motor M includes an AC power supply 10, a rectifier circuit 20, an electrolytic capacitor 30, a voltage sensor 40, an inverter 50, current sensors 61 to 63, And a control device 70 for controlling the operation of the inverter 50.
- the AC power supply 10 supplies AC power of a commercial frequency (50 Hz / 60 Hz).
- the rectifier circuit 20 is, for example, a full-wave rectifier circuit including four diodes, and converts AC power into DC power.
- the electrolytic capacitor 30 removes a pulsating flow of the DC power output from the rectifier circuit 20.
- the voltage sensor 40 measures a DC input voltage Vi input to the inverter 50.
- the inverter 50 is, for example, a circuit including six switching elements forming a three-phase full bridge.
- the inverter 50 turns on and off the switching element based on the PWM signal S output from the control device 70 and input to the switching element, thereby converting the input DC power to the frequency required to drive the motor M. And output (supply) to the motor M.
- the switching element is a switching element configured using a wide band gap semiconductor (such as SiC or GaN).
- the current sensors 61 to 63 are, for example, CTs (Current Transformers) and measure the AC motor currents Iu, Iv, Iw flowing through the windings of the respective phases u, v, w of the motor M.
- CTs Current Transformers
- the control device 70 includes an applied voltage calculation unit 71, a carrier wave generation unit 72, a comparison unit 73, a PWM signal output unit 74, and a carrier frequency setting device 7A.
- the control device 70 can be realized by using, for example, a microcomputer or an arithmetic circuit. Further, the control device 70 can control the operation of the motor M by, for example, vector control. Since the configuration other than the configuration related to the carrier frequency can be realized by a known technique, a detailed description thereof is omitted here.
- the applied voltage calculation unit 71 measures a speed command value (command value of the rotation speed of the motor M) input from the outside, a torque command value (command value of the torque of the motor M) also input from the outside, and measures the voltage sensor 40.
- the input voltage Vi and the motor currents Iu, Iv, Iw measured by the current sensors 61 to 63 are input, and based on these, the voltage applied to each phase of the motor M is calculated and the voltage is indicated. Generate a voltage command signal.
- the carrier frequency setting device 7A has a carrier frequency setting unit 75.
- the carrier wave generation unit 72 generates a carrier wave (carrier wave used for generating the PWM signal S) in the PWM control.
- a carrier wave carrier wave used for generating the PWM signal S
- the comparing section 73 compares the voltage command signal generated by the applied voltage calculating section 71 with a triangular wave (carrier wave) generated by the carrier wave generating section 72.
- the PWM signal output unit 74 outputs a pulse signal corresponding to the result of the comparison in the comparison unit 73 to the inverter 50 as a PWM signal S.
- the inverter 50 turns on / off the switching element based on the PWM signal S, converts the input DC power into AC power, and outputs the AC power to the motor M.
- the carrier frequency setting unit 75 sets a carrier frequency (a carrier frequency of the inverter 50) which is a frequency of a carrier wave.
- the carrier wave generation unit 72 generates a triangular wave of the carrier frequency set by the carrier frequency setting unit 75.
- the carrier frequency setting unit 75 sets the carrier frequency according to the command value of the rotation speed of the motor M and the command value of the torque of the motor M.
- the carrier frequency is increased when the motor torque is small (the carrier frequency is decreased when the motor torque is large). It may not be preferable to do so.
- the present inventor considered that the overall efficiency of the motor drive system was to be a high efficiency motor drive system from the viewpoint of the total high efficiency calculated from the total loss of the motor loss and the inverter loss.
- the carrier frequency was investigated. The results will be described below.
- the value obtained by subtracting the output of the motor M from the input power to the inverter 50 is the energy (loss) lost in the motor drive system.
- the breakdown of the loss was examined assuming that this loss is equal to the sum of the loss of the motor M and the loss of the inverter 50.
- the loss of the motor M includes not only iron loss and copper loss but also mechanical loss, wind loss, bearing loss and the like.
- the iron loss shown below includes these losses. Even in this case, if the rotation speed is the same, a certain amount of the loss (mechanical loss, windage loss, bearing loss, etc.) is included in the loss of the motor M, but the torque of the motor M changes. It is considered that there will be no problem in verifying the tendency of the loss of the motor drive system to increase or decrease. Therefore, here, it is assumed that the loss of the motor M is composed of iron loss (however, loss including mechanical loss, wind loss and bearing loss) and copper loss.
- the range of the carrier frequency is set to 5 kHz to 50 kHz.
- the motor M to be evaluated is the IPMSM.
- the basic specifications of the motor M are as follows. Further, as a semiconductor element constituting a switching element of the inverter 50, an SiC semiconductor element which is one of wide band gap semiconductor elements was used. ⁇ Number of phases: 3 ⁇ Number of poles: 12 -Stator outer diameter: 135mm -Stator inner diameter: 87mm ⁇ Number of stator slots: 18 (concentrated winding) -Stator (core) material; non-oriented electrical steel sheet (35A300) ⁇ Rotor outer diameter: 85mm ⁇ Thickness of rotor (core); 30mm ⁇ 1.1T residual magnetic flux density of the permanent magnet in the rotor
- FIGS. 2-1 and 2-2 are diagrams showing, in the form of a table, loss measurement results when the rotation ratio of the motor M is 1.00.
- the rotation speed ratio is a ratio of the rotation speed at the time of measurement to the maximum rotation speed of the motor M.
- a rotation speed ratio of 1.00 indicates that the measurement was performed at the same rotation speed as the maximum rotation speed.
- 2-1 (a), 2-1 (b), 2-1 (c), 2-2 (a), and 2-2 (b) show that the torque ratio is 0.05,
- the measurement results at 0.125, 0.25, 0.375, and 0.5 are shown.
- the torque ratio is a ratio of the torque at the time of measurement to the maximum torque of the motor M.
- a torque ratio of 0.5 indicates that the measurement was performed at a torque of 50% of the maximum torque.
- the maximum rotation speed and the maximum torque of the motor M are appropriately designed and determined according to the use of the motor M.
- f c indicates a carrier frequency.
- the ratio of the output power of the motor M to the input power of the inverter 50 is referred to as overall efficiency.
- the overall efficiency ratio, to the maximum overall efficiency in the same rotational speed ratio is the ratio of the overall efficiency of the carrier frequency f c.
- the sum of the copper loss and the iron loss of the motor M and the loss of the inverter 50 is referred to as a total loss.
- the overall loss ratio, total for the loss, the carrier frequency when the same carrier frequency f c in the rotation speed ratio and the same torque ratio minimum (5 kHz in this case) which is the ratio of the total loss in the f c.
- the it is the ratio of the copper loss of the motor M of the carrier frequency f c.
- FIG. 3 is a diagram showing the relationship between the overall efficiency ratio and the carrier frequency shown in FIGS. 2-1 and 2-2 in a graph format.
- a carrier frequency at which the overall efficiency is maximum (the overall loss is minimum) within the same torque ratio is referred to as an optimum carrier frequency as necessary.
- the total efficiency ratio is 1.000 when the carrier frequency is 30 kHz and 40 kHz, but the total efficiency when the carrier frequency is 40 kHz is calculated from the fourth decimal place.
- the ratio (1.0000) was larger than the total efficiency ratio (0.9997) when the carrier frequency was 30 kHz.
- the optimum carrier frequency has the lowest value in the relationship between the optimum carrier frequency and the torque of the motor M. Further, it can be seen that the range of the torque corresponding to the lowest carrier frequency is only one (only the torque ratio of 0.250). Then, in a range where the torque of the motor M is equal to or higher than the torque of the motor M corresponding to the lowest optimal carrier frequency, it can be seen that the optimal carrier frequency becomes the same or higher as the torque of the motor M increases.
- the optimal carrier frequency becomes the same or lower as the torque of the motor M increases.
- the optimal carrier frequency has a minimum value and corresponds to the minimum optimal carrier frequency.
- the carrier frequency can be made the same or lower to improve the overall efficiency of the motor drive system.
- FIGS. 4-1 and 4-2 are diagrams showing the relationship between the total loss ratio and the carrier frequency shown in FIGS. 2-1 and 2-2 in a graph format. 4-1 (a), 4-1 (b), 4-1 (c), 4-2 (a), and 4-2 (b) show that the torque ratio is 0.05 , 0.125, 0.25, 0.375, 0.5 (FIG. 2-1 (a), FIG. 2-1 (b), FIG. 2-1 (c), FIG. 2-2 (a), FIG. The result at the time of 2-2 (b)) is shown.
- the iron loss of the motor M with respect to the total loss is reduced.
- the loss ratio is large. Therefore, by increasing the carrier frequency, iron loss of the motor M can be reduced.
- the carrier frequency is increased, the loss of the inverter 50 increases. Also, the sum of the iron loss ratio and the copper loss ratio gradually decreases and approaches a constant value as the carrier frequency increases.
- the carrier frequency at which the total loss is minimized is determined based on the balance between the decrease in the loss of the motor M and the increase in the loss of the inverter 50 as described above. Therefore, when the torque ratio is 0.05 and 0.125, it is considered that the optimum carrier frequency is 40 kHz.
- FIG. 4-1 (c) under the condition that the torque ratio is 0.25 (hereinafter, referred to as medium load condition), FIG. 4-1 (a) and FIG. 4-2 (b)
- the ratio of the copper loss of the motor M to the total loss is larger than under the low load condition shown.
- the sum of the iron loss ratio and the copper loss ratio approaches a certain value while gradually decreasing as the carrier frequency increases, but the sum of the iron loss ratio and the copper loss ratio becomes smaller.
- the carrier frequency that becomes substantially constant is 20 kHz, which is lower than that under the low load condition. Further, as in the case of the low load condition, when the carrier frequency is increased, the loss of the inverter 50 increases.
- the carrier frequency is equal to or higher than 20 kHz
- the amount of increase in the loss of the inverter 50 with respect to the increase in the carrier frequency is larger than under the low load condition (when the carrier frequency is equal to or higher than 40 kHz) (the increase in the loss of the inverter 50 is smaller).
- the balance of the loss of the motor M as described above and the increase of the loss of the inverter 50 determine the carrier frequency at which the total loss is minimized, and the carrier frequency is lower than that under the low load condition. For this reason, when the torque ratio is 0.25, it is considered that the optimum carrier frequency is 20 kHz.
- FIGS. 4-2 (a) and 4-2 (b) under the conditions where the torque ratio is 0.375 and 0.5 (hereinafter, referred to as high load conditions), FIG.
- the ratio of the copper loss of the motor M to the total loss is larger than under the medium load condition shown in (c).
- the inverter loss ratio increases.
- the inverter loss ratio at each carrier frequency increases.
- the carrier frequency at which the total loss is minimized is determined by the above-described reduction in the loss of the motor M and the increase in the loss of the inverter 50, and the carrier frequency becomes higher than that under the medium load condition.
- the carrier frequency increases as the torque of the motor M increases. For this reason, when the torque ratio is 0.375 and 0.5, the optimum carrier frequencies are considered to be 30 kHz and 40 kHz, respectively.
- the optimal carrier frequency is set to be the same or lower, and in a range where the torque of the motor M is equal to or more than the torque of the motor M corresponding to the lowest optimal carrier frequency, the optimal carrier frequency becomes , The same or higher, the efficiency of the entire motor drive system can be maximized (loss is minimized).
- the inventor has determined that the optimum carrier frequency has a minimum value in the relationship between the optimum carrier frequency and the torque of the motor M, regardless of the rotation speed of the motor M, and corresponds to the lowest optimum carrier frequency.
- the torque of the motor M is equal to or more than the torque of the motor M
- FIGS. 5-1 to 13-3 The contents of the items in the tables of FIGS. 5-1 to 5-3, FIGS. 8-1 to 8-3, and FIGS. 11-1 to 11-3 are shown in FIGS. 2-1 and 2-2. Is the same as the content of the item.
- FIG. 5-1 to 5-3 “FIGS. 8-1 to 8-3”, and “FIGS. 11-1 to 11-3” respectively show that the rotation ratio of the motor M is 0.75, It is a figure which shows the measurement result of the loss at the time of 0.50 and 0.25 in a table form.
- FIG. 5-1 (a) / FIG. 8-1 (a) / FIG. 11-1 (a) "FIG. 5-1 (b) / FIG. 8-1 (b) / FIG. 11-1 (b)”
- FIG. 5-1 (c), FIG. 8-1 (c), FIG. 11-1 (c) "FIG. 5-2 (a), FIG. 8-2 (a), FIG. a), “FIG. 5-2 (b), FIG.
- FIGS. 6, 9 and 12 show the overall efficiency ratios and carrier ratios shown in FIGS. 5-1 to 5-3, FIGS. 8-1 to 8-3, and FIGS. 11-1 to 11-3, respectively. It is a figure which shows the relationship with a frequency in a graph form.
- FIG. 6B is an enlarged view of a region where the overall efficiency ratio of FIG. 6A is 0.980 to 1.005.
- FIG. 9B is an enlarged view of a region where the total efficiency ratio of FIG. 9A is 0.95 to 1.01.
- FIG. 12B is an enlarged view of a region where the overall efficiency ratio of FIG. 12A is 0.90 to 1.00.
- FIGS. 7-1 to 7-3, FIGS. 10-1 to 10-3, and FIGS. 13-1 to 13-3 correspond to FIGS. 5-1 to 5-3 and FIGS. 8-1 to 8, respectively.
- FIG. 3 is a graph showing a relationship between the total loss ratio and the carrier frequency shown in FIGS. 11-1 to 11-3 in a graph format. “FIG. 7-1 (a) / FIG. 10-1 (a), FIG. 13-1 (a)”, “FIG. 7-1 (b) / FIG. 10-1 (b), FIG. 13-1 (b) , “FIG. 7-1 (c) / FIG. 10-1 (c), FIG. 13-1 (c)", "FIG. 7-2 (a) / FIG. 10-2 (a), FIG. 13-2 ( a), “FIG.
- the optimum carrier is the same as when it is 1.00.
- the optimum carrier frequency has a minimum value, and in a range where the torque of the motor M is equal to or more than the torque of the motor M corresponding to the lowest optimum carrier frequency, It can be seen that as the torque increases, the optimal carrier frequency will be the same or higher.
- the total efficiency ratio when the carrier frequency is 10 kHz and 15 kHz is 0.999, but when calculated to the fourth decimal place, the total efficiency ratio when the carrier frequency is 10 kHz is calculated.
- the ratio was larger than the total efficiency ratio when the carrier frequency was 15 kHz.
- the total efficiency ratios when the carrier frequency is 10 kHz and 15 kHz are 0.995 and 0.991, respectively.
- the overall efficiency ratio when the carrier frequency was 15 kHz was higher than the overall efficiency ratio when the carrier frequency was 10 kHz.
- the total efficiency ratios when the carrier frequency is 5 kHz and 10 kHz are 0.977 and 0.983, respectively, When calculated thereafter, the overall efficiency ratio when the carrier frequency was 10 kHz was larger than the overall efficiency ratio when the carrier frequency was 5 kHz.
- the rotational speed ratio of the motor M is 0.25, 0.50, and 0.75
- the excitation fundamental frequency is lower than when the rotational speed ratio of the motor M is 1.00, so that the carrier frequency is increased.
- the effect of reducing the sum of the copper loss ratio and the iron loss ratio is reduced (partly, due to the influence of measurement variations, the sum of the copper loss ratio and the iron loss ratio increases as the carrier frequency increases. ing).
- the torque of the motor M is set to the lowest optimal value as when the rotational speed ratio of the motor M is 1.00.
- the efficiency of the entire motor drive system is maximized by setting the optimum carrier frequency to be the same or higher. Can be minimized).
- Table 1 shows the above results.
- Table 1 shows the torque ratio and the optimum carrier frequency for each rotation ratio of the motor M, obtained from the results shown in FIGS. 2-1 to 13-2.
- the case where the interval for changing the torque ratio is set to 0.125 (or 0.075) is shown as an example.
- the intervals at which the torque ratio is changed are based on the intervals shown in FIGS. 2-1 to 2-2, FIGS. 5-1 to 5-3, FIGS. 8-1 to 8-3, and FIGS. 11-1 to 11-3. If the value is also small, the optimum carrier frequency may (slightly) increase or decrease due to measurement variations or the like even in the torque ratio range where the optimum carrier frequency is the same in Table 1.
- the optimal carrier frequency is 5 kHz when the torque ratio is in the range of 0.05 to 0.125, but when the torque ratio is between 0.05 and 0.125,
- the optimal carrier frequency may increase or decrease for 5 kHz. Therefore, in the above description, in order to maximize the overall efficiency of the motor drive system, in the range of the torque ratio derived from the relationship that the optimum carrier frequency is the same value even if the torque of the motor M changes. However, it is not necessary to set the carrier frequency to be completely the same as the optimal carrier frequency, but it is only necessary that the carrier frequency be substantially equal. The difference of about 5% of the carrier frequency has a small effect on the value of the optimum carrier frequency at which the total loss is minimized. Therefore, “substantially equivalent” in this specification means “the difference in carrier frequency is 5% or less”.
- the relationship between the torque of the motor M and the optimum carrier frequency is such that the higher the torque of the motor M, the higher the optimum carrier frequency, regardless of the rotational speed ratio of the motor M.
- the optimal carrier frequency changes from 5 kHz to 10 kHz. Get higher.
- the torque ratio changes from 0.625 to 0.750 and the torque of the motor M increases
- the optimum carrier frequency changes from 10 kHz to 15 kHz and thus increases.
- the rotation ratio of the motor M is 1.00, the torque ratio changes from 0.250 to 0.375 and from 0.375 to 0.500, and the torque of the motor M increases.
- the optimum carrier frequency becomes the lowest value of 5 kHz when the torque ratio is in the range of 0.05 to 0.125, and when the torque ratio is in the other range, The value of the carrier frequency is higher than 5 kHz.
- the optimal carrier frequency becomes the minimum value of 20 kHz when the torque ratio is 0.250, and the value of the optimal carrier frequency is 20 kHz in other torque ratio ranges. Higher than. Therefore, in a range where the torque ratio of the motor M is smaller than the range of the torque ratio corresponding to the lowest optimum carrier frequency, when the torque ratio of the motor M increases, the optimum carrier frequency becomes the same or lower.
- the optimum carrier frequency should be the same or higher as the torque ratio of the motor M increases.
- the efficiency of the entire motor drive system can be maximized (loss can be minimized).
- the present inventor also maximizes the efficiency of the entire motor drive system by making the optimum carrier frequency substantially equal or higher when the torque of the motor M increases in other IPMSMs and the inverter 50 ( It has been confirmed that there is a torque range in which loss can be minimized). Further, the value itself of the inverter loss ratio and the sum of the iron loss ratio and the copper loss ratio varies depending on the type of the inverter or the motor M, but the inverter loss ratio and the iron loss ratio and the copper loss ratio with respect to the change in the carrier frequency. It is considered that the behavior of the change with the sum does not greatly differ depending on the type of the motor M. Therefore, when the torque of the motor M increases, the efficiency of the entire motor drive system can be maximized (minimizing the loss) by making the carrier frequency substantially equal or higher. The same applies to other types of motors M.
- the carrier frequency setting unit 75 sets the carrier frequency according to the command value of the rotation speed of the motor M and the command value of the torque of the motor M. For this reason, the relationship between the rotation speed and torque of the motor M and the optimum carrier frequency is stored in advance.
- An example of a method for deriving the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M will be described with reference to the flowchart of FIG.
- the flowchart in FIG. 14 is an example of a preparation process performed before using the motor M in an actual machine (for example, a train, a hybrid car, a home electric appliance, and the like).
- step S1401 the control device 70 designates one unselected candidate among a plurality of candidates for the number of rotations of the motor M preset for the control device 70.
- step S1402 the control device 70 specifies one unselected candidate among the plurality of motor M torque candidates preset for the control device 70.
- step S1403 the control device 70 designates one unselected candidate among a plurality of carrier frequency candidates preset for the control device 70.
- step S1404 the control device 70 generates a PWM signal S based on the contents specified in steps S1401 to S1403, and outputs the PWM signal S to the inverter 50.
- the inverter 50 operates the motor M based on the PWM signal S.
- the applied voltage calculation unit 71 sets the rotation speed specified in step S1401 as a command value of the rotation speed of the motor M, and sets the torque specified in step S1402 as a command value of the torque of the motor M.
- the voltage applied to the phase is calculated, and a voltage command signal indicating the voltage is generated.
- the carrier wave generator 72 generates a triangular wave having the carrier frequency specified in step S1403.
- step S1405 the total loss when the motor M is operated in step S1404 (the total loss when the motor M is driven using the inverter 50) is measured.
- the total loss is the sum of the copper loss and the iron loss of the motor M and the loss of the inverter 50.
- the total loss is derived as a value obtained by subtracting the output of the motor M from the input power to the inverter 50.
- the copper loss of the motor M is derived as a Joule loss from the current flowing through the winding of each phase u, v, w of the motor M and the winding resistance.
- the iron loss of the motor M is derived as a value obtained by subtracting the output of the motor M and the copper loss from the input power to the motor M.
- the loss of the inverter 50 is derived as a value obtained by subtracting the output power of the inverter (input power to the motor M) from the input power to the inverter 50.
- the control device 70 determines whether or not all of the plurality of carrier frequency candidates preset for the control device 70 have been designated. If the result of this determination is that all of the plurality of carrier frequency candidates have not been specified, processing returns to step S1403. Then, the processing of steps S1403 to S1406 is repeatedly executed until all of the plurality of candidates for the carrier frequency are designated. That is, the measurement (derivation) of the total loss in step S1405 is performed by changing the carrier frequency in the inverter 50.
- step S1406 If it is determined in step S1406 that all of the plurality of candidates for the carrier frequency have been specified, the rotation speed specified in step S1401 and the number of rotations specified in step S1402 are determined using the triangular waves of all the candidates for the carrier frequency.
- the total loss when driving the motor M by generating the PWM signal S with the commanded torque as the command value is obtained in step S1405 which is repeatedly executed. Then, the process proceeds to step S1407.
- step S1407 the control device 70 drives the motor M by generating a PWM signal S having the rotation speed of the motor M specified in step S1401 and the torque of the motor M specified in step S1402 as command values.
- the carrier frequency with the smallest total loss among the total losses in the case is specified as the optimal carrier frequency (that is, based on the total loss derived in step S1405, the carrier frequency at which the total loss is minimized is determined as the optimal carrier frequency. Is derived as).
- the optimum carrier frequency may be specified as follows. At the stage where the process has proceeded to step S1407, a set of the carrier frequency candidates designated in step S1403 and the total loss measured in step S1405 when the carrier frequency is designated is obtained by the number of carrier frequency candidates. Have been.
- the control device 70 derives an expression indicating the relationship between the carrier frequency and the total loss by a known method such as the least square method, based on the pair of the carrier frequency candidate and the total loss. In this equation, control device 70 specifies the carrier frequency at which the total loss is minimized as the optimum carrier frequency.
- step S1408 the control device 70 determines whether or not all of the plurality of motor M torque candidates preset for the control device 70 have been designated. As a result of this determination, if all of the plurality of candidates for the torque of the motor M have not been specified, the process returns to step S1402. Then, the processing of steps S1402 to S1408 is repeatedly executed until all of the plurality of candidates for the torque of the motor M are designated. That is, the measurement (derivation) of the total loss in step S1405 is performed by changing the torque generated in the motor M. The derivation of the optimal carrier frequency in step S1407 is performed for each of the plurality of torques.
- step S1408 If it is determined in step S1408 that all of the plurality of candidates for the torque of the motor M have been specified, the rotation speed of the motor M specified in step S1401 is determined using the triangular waves of all the candidates for the carrier frequency.
- the optimum carrier frequency when the motor M is driven by generating the PWM signal S using each of the torque candidates of the motor M as a command value is obtained in the repeatedly executed step S1407. Then, the process proceeds to step S1409.
- step S1409 the control device 70 derives the relationship between the torque of the motor M and the optimum carrier frequency for the rotation speed of the motor M specified in step S1401.
- the control device 70 extracts the optimum carrier frequency for the torque of the motor M specified in step S1402 for each of the torques of the motor M specified in step S1402 that are repeatedly executed.
- a set of the torque of the motor M and the optimum carrier frequency in the torque of the motor M is obtained by the number of torque candidates of the motor M.
- the control device 70 derives a set of the torque of the motor M obtained as described above and the optimum carrier frequency in the torque of the motor M as a relationship between the torque of the motor M and the optimum carrier frequency.
- step S1410 the control device 70 determines whether or not all of the plurality of candidates for the rotation speed of the motor M preset for the control device 70 have been specified. If the result of this determination is that all of the plurality of candidates for the number of revolutions of the motor M have not been specified, the process returns to step S1401. Then, the processing of steps S1401 to S1410 is repeatedly executed until all of the plurality of candidates for the rotation speed of the motor M are designated. That is, the measurement (derivation) of the total loss in step S1405 is performed by changing the rotation speed of the motor M. The derivation of the optimum carrier frequency in step S1407 is performed for each of the plurality of rotation speeds.
- step S1410 If it is determined in step S1410 that all of the plurality of candidates for the rotation speed of the motor M have been specified, the relationship between the torque of the motor M and the optimum carrier frequency is determined for each of all the candidates for the rotation speed of the motor M. This is obtained in step S1409, which is repeatedly executed. Then, the process proceeds to step S1411.
- step S1411 the control device 70 derives and stores the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M based on the optimum carrier frequency derived in step S1407. This relationship is as shown in Table 1.
- the relationship between the torque of the motor M derived for each rotation speed of the motor M by the control device 70 and the optimal carrier frequency is as follows.
- the torque of the motor M is equal to the plurality of optimum carrier frequencies specified in step S1407 (the plurality of optimum carrier frequencies specified under the condition where the rotation speed of the motor M is common and the torque of the motor M is different from each other).
- the motor M has a portion (first portion) where the carrier frequency becomes higher as the torque increases.
- the lowest optimal carrier frequencies are 5 kHz, 5 kHz, 5 kHz, and 20 kHz, respectively.
- the torque ratios corresponding to the lowest optimal carrier frequency are 0.050 and 0.125, 0.050 and 0.125, 0.050 and 0.125, and 0.250, respectively.
- the torque ratio is equal to or more than the torque ratio corresponding to the lowest optimal carrier frequency. In the ranges of 0.250, 0.125 to 0.250, 0.125 to 0.250, and 0.250 to 0.500, the torque ratios are 0.125 to 0.250 and 0.125, respectively.
- the optimal carrier frequencies are 5 to 10, 5 to 10, 5 to 10, 20 to 30 and 30 to 40, respectively, and become higher.
- the relationship between the torque of the motor M derived for each rotation speed of the motor M by the control device 70 and the optimum carrier frequency is such a relationship.
- step S1411 the relationship derived in step S1411 is that the torque ratio of the motor M is the plurality of rotational speed ratios of the motor M derived in step S1407. (“0.25", “0.50”, “0.75", “1.00") among the optimum carrier frequencies ("5", "5" 10), the torque ratio of the motor M (“0.050”, “0.125”) corresponding to the lowest carrier frequency “5” or more is optimal if the torque ratio of the motor M increases. There is a first portion (a portion where the torque ratio of the motor M is 0.050 or more and 1.000 or less) where the carrier frequency is increased.
- the “first portion where the optimum carrier frequency increases when the torque ratio of the motor M increases” may include “the portion where the optimal carrier frequency is substantially equal even when the torque ratio of the motor M increases”. .
- the first portion includes “the torque ratio of the motor M is Even if it becomes large, the part where the optimum carrier frequency is almost the same (the part where the torque ratio of the motor M is 0.050 or more and 0.125 or less, and the part where the torque ratio of the motor M is 0.250 or more and 1.000 or less) Part) "is included.
- step S1411 the relationship derived in step S1411 is that the torque ratio of the motor M is the optimal carrier frequency (“5”, “5”) derived in step S1407. 10), the torque ratio of the motor M (“0.050”, “0.125”) corresponding to the lowest carrier frequency “5” or more is optimal if the torque ratio of the motor M increases. There is a first portion (a portion where the torque ratio of the motor M is 0.050 or more and 1.000 or less) where the carrier frequency is increased.
- the first portion includes “the torque ratio of the motor M is Even if it becomes large, the part where the optimum carrier frequency is almost the same (the part where the torque ratio of the motor M is 0.050 or more and 0.125 or less, and the part where the torque ratio of the motor M is 0.250 or more and 1.000 or less) Part) "is included.
- step S1411 the relationship derived in step S1411 is that the torque ratio of the motor M is the optimum carrier frequency (“5”, “5”) derived in step S1407. 10) and “15”), the torque ratio of the motor M is equal to or greater than the torque ratio (“0.050”, “0.125”) of the motor M corresponding to the lowest carrier frequency “5”.
- a first portion a portion where the torque ratio of the motor M is equal to or greater than 0.050 and equal to or less than 0.750 where the optimum carrier frequency increases as the size increases.
- the first portion includes “the torque ratio of the motor M is Even if it becomes large, the part where the optimum carrier frequency is substantially equal (the part where the torque ratio of the motor M is 0.050 or more and 0.125 or less, and the part where the torque ratio of the motor M is 0.250 or more and 0.625 or less) Part) "is included.
- step S1411 the relationship derived in step S1411 is that the torque ratio of the motor M is the optimal carrier frequency (“20”, “20”) derived in step S1407. 30 ”and“ 40 ”), when the torque ratio of the motor M increases in a range where the torque ratio of the motor M corresponding to the lowest carrier frequency“ 20 ”is equal to or more than“ 0.250 ”, the optimum carrier frequency (A portion where the torque ratio of the motor M is 0.250 or more and 0.500 or less).
- the control device If there is a range in which the torque of the motor M is equal to or less than the torque of the motor M corresponding to the lowest optimum carrier frequency among the plurality of optimum carrier frequencies specified as described above, the control device The relationship between the torque of the motor M and the optimum carrier frequency derived for each rotation speed of the motor M by 70 has a portion (second portion) where the carrier frequency decreases as the torque of the motor M increases.
- the torque ratio corresponding to the lowest optimal carrier frequency is 0.250
- the torque ratio corresponding to the lowest optimal carrier frequency is 0.250
- the torque ratio changes from 0.125 to 0.250 in the range of 0.125 to 0.250, which is the range of the torque ratio of 0.250 or less, which is the torque ratio corresponding to the lowest optimum carrier frequency.
- the optimal carrier frequency changes from 40 to 20 and decreases.
- the relationship between the torque of the motor M derived by the control device 70 and the optimum carrier frequency is such a relationship.
- step S1411 the relationship derived in step S1411 is that the torque ratio of the motor M is the optimal carrier frequency (“20”, “20”) derived in step S1407. 30 ”and“ 40 ”), when the torque ratio of the motor M increases in a range that is equal to or less than the torque ratio (“ 0.250 ”) of the motor M corresponding to the lowest carrier frequency“ 20 ”, the optimum carrier frequency (A portion where the torque ratio of the motor M is equal to or greater than 0.050 and equal to or less than 0.250).
- the “second portion where the optimal carrier frequency decreases when the torque ratio of the motor M increases” may include “a portion where the optimal carrier frequency is substantially equal even when the torque ratio of the motor M increases”. .
- the second portion (the portion where the torque ratio of the motor M is 0.050 or more and 0.250 or less) includes “the torque ratio of the motor M is Even if it increases, the portion where the optimum carrier frequency is substantially equal (the portion where the torque ratio of the motor M is equal to or greater than 0.050 and equal to or less than 0.125) is included.
- the control device 70 determines the relationship between the torque of the motor M and the optimum carrier frequency (a set of the torque of the motor M and the optimum carrier frequency of the motor M) for each of all the candidates for the rotation speed of the motor M. From the above, it is possible to derive a table that stores the rotation speed of the motor M, the torque of the motor M, and the optimum carrier frequency in association with each other as the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M. it can. The control device 70 also determines the relationship between the torque of the motor M and the optimal carrier frequency for each of all the candidates for the number of rotations of the motor M (a set of the torque of the motor M and the optimal carrier frequency of the motor M). Accordingly, an equation indicating the relationship between the torque of the motor M and the optimum carrier frequency can be derived for each rotation speed of the motor M by a known method such as the least square method. Then, the processing according to the flowchart in FIG. 14 ends.
- the carrier frequency setting unit 75 determines the command value of the torque of the motor M and the command of the rotation speed of the motor M based on the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M.
- the optimum carrier frequency corresponding to the value is extracted as the carrier frequency in the inverter 50 (that is, the carrier frequency corresponding to the command value of the torque of the motor M and the command value of the rotation speed of the motor M is set based on the above-described relationship. Do).
- the carrier frequency setting unit 75 In a range where the torque is equal to or higher than the torque of the motor M corresponding to the lowest optimum carrier frequency (20 kHz) (the torque ratio of the motor M is in a range of 0.250 to 0.500), when the torque of the motor M increases, the frequency increases from 20 kHz to 40 kHz. Is set as the carrier frequency in the inverter 50.
- the carrier frequency setting unit 75 sets a range in which the torque of the motor M is equal to or less than the torque of the motor M corresponding to the lowest optimal carrier frequency (20 kHz) (the torque ratio of the motor M is in a range of 0.050 to 0.250).
- the optimum carrier frequency which decreases from 40 kHz to 20 kHz when the torque of the motor M increases, is set as the carrier frequency in the inverter 50.
- the table may not have the same value as the command value (the rotation speed and the torque of the motor M).
- the carrier frequency setting unit 75 performs, for example, an interpolation process or an extrapolation process on the value stored in the table based on the command value, thereby obtaining the same value as the command value (for the motor M).
- the optimum carrier frequency corresponding to the rotation speed and the torque) can be derived as the carrier frequency in the inverter 50.
- the carrier wave generation section 72 generates a triangular wave of the carrier frequency set by the carrier frequency setting section 75 in this way.
- the value of the optimum carrier frequency in the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M is used as the carrier frequency applied to the inverter 50. Therefore, the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M is the same as the relationship between the torque of the motor M and the carrier frequency applied to the inverter 50 for each rotation speed of the motor M.
- the torque of the motor M is equal to or higher than the torque at which the optimum carrier frequency is the lowest.
- the relationship between the torque of the motor M and the optimum carrier frequency is determined for each rotation speed of the motor M such that the optimum carrier frequency becomes substantially equal or higher when the torque of the motor M increases.
- the carrier frequency can be set in consideration of the iron loss and the copper loss of the motor M and the switching loss in the inverter 50 so that the efficiency of the entire motor drive system is increased. Therefore, the motor M can be driven such that the total loss of the loss of the motor M and the loss of the inverter 50 is reduced.
- the relationship between the torque of the motor M and the optimum carrier frequency is derived for each rotation speed of the motor M by performing actual measurement.
- the relationship between the motor torque and the optimum carrier frequency does not necessarily need to be derived for each rotation speed of the motor M in this manner.
- the overall loss of the motor drive system when the motor M is excited by the inverter 50 may be derived using numerical analysis.
- the control device 70 derives the relationship between the torque of the motor M and the optimum carrier frequency for each rotation speed of the motor M.
- the relationship between the torque of the motor M and the optimum carrier frequency may be derived for each rotation speed of the motor M by an information processing device different from the control device 70.
- the control device 70 acquires the relationship between the torque of the motor M and the optimum carrier frequency derived for each rotation speed of the motor M in the information processing device.
- the relationship between the torque of the motor M and the optimum carrier frequency may be stored inside the control device 70 for each rotation speed of the motor M, or may be stored outside the control device 70 for each rotation speed of the motor M. It may be stored.
- the AC power supply 10 and the rectifier circuit 20 are used to generate input power to the inverter 50.
- a DC power supply can be used as an alternative to the AC power supply 10 and the rectifier circuit 20.
- the DC power supply may have a step-up / step-down function.
- the DC power supply may have a power storage function and store regenerative power from the motor M.
- the switching element forming the inverter 50 is a switching element formed using a wide band gap semiconductor
- the switching element configuring the inverter 50 is a switching element configured using a semiconductor other than a wide band gap semiconductor (a semiconductor having a general band gap).
- the present embodiment and the first embodiment mainly differ from each other mainly in the configuration due to the difference in the switching elements constituting the inverter 50. Therefore, in the description of the present embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals as those in FIGS. 1 to 14, and the detailed description is omitted.
- FIGS. 15A and 15B are diagrams showing, in the form of a table, loss measurement results when the rotation speed ratio of the motor M is 1.00.
- FIGS. 15-1 (a), (b), FIGS. 15-2 (a), (b) show FIGS. 2-1 (a), (b), FIGS. 2-2 (a), (b), respectively.
- FIG. 16 is a graph showing the relationship between the overall efficiency ratio and the carrier frequency shown in FIGS. 15-1 and 15-2 in a graph format.
- FIG. 16 is a diagram corresponding to FIG.
- FIGS. 17-1 and 17-2 are graphs showing the relationship between the total loss ratio and the carrier frequency shown in FIGS. 15-1 and 15-2.
- FIGS. 17-1 (a), (b), (c), and FIGS. 17-2 (a), (b) show FIGS. 4-1 (a), (b), (c), and FIG. It is a figure corresponding to 2 (a) and (b).
- FIGS. 18-1 to 18-3, FIGS. 21-1 to 21-3, and FIGS. 24-1 to 24-3 show that the rotational speed ratios of the motor M are 0.75, 0.50, 0. It is a figure which shows the measurement result of the loss at the time of 25 in a table form.
- FIGS. 19, 22 and 25 show the overall efficiency ratios and carrier frequencies shown in FIGS. 18-1 to 18-3, FIGS. 21-1 to 21-3, and FIGS. 24-1 to 24-3, respectively.
- FIG. 6 is a diagram showing a relationship in a graph format.
- FIGS. 20-1 to 20-3, FIGS. 23-1 to 23-3, and FIGS. 26-1 to 26-3 correspond to FIGS. 18-1 to 18-3 and FIGS. 21-1 to 21, respectively.
- FIG. 3B is a diagram showing, in a graph form, the relationship between the total loss ratio and the carrier frequency shown in FIGS. 24-1 to 24-3. 20-1 (a), (b), (c) to FIG. 20-3 (a), (b), (c), FIG. 23-1 (a), (b), (c) to FIG.
- FIGS. 26-1 (a), (b), (c) to FIGS. 26-3 (a), (b), (c) 7-1 (a), (b), (c) to FIG. 7-3 (a), (b), (c), FIG. 10-1 (a), (b), (c) to FIG. 3 (a), (b), (c), and FIGS. 13-1 (a), (b), (c) to 13-3 (a), (b), (c). .
- the inverter loss ratio becomes larger. This is because the switching loss of the switching element is smaller when a wide band gap semiconductor is used as the switching element than when a general semiconductor other than the wide band gap semiconductor is used as the switching element. This switching loss tends to increase as the carrier frequency increases.
- the optimum carrier frequency becomes 5 kHz even when the rotation speed ratio and the torque ratio of the motor M are changed.
- a semiconductor other than a wide bandgap semiconductor is used as a switching element, as described in the first embodiment, in a region where the carrier frequency is low, as the carrier frequency increases, the sum of the iron loss ratio and the copper loss ratio gradually increases. And then approach a certain value.
- the loss (and the inverter loss ratio) of the inverter 50 increases as compared with the case where the wide bandgap semiconductor is used as the switching element.
- the increase in the loss (and the inverter loss ratio) of the inverter 50 with respect to the increase in the carrier frequency also increases (the increase in the loss (and the inverter loss ratio) of the inverter 50 becomes sharper).
- the optimum carrier frequency becomes substantially equal regardless of the rotation speed and torque of the motor M.
- the intervals at which the torque ratio is changed are set in FIGS. 15-1 to 15-2, FIGS. 18-1 to 18-3, FIGS. 21-1 to 21-3, and FIGS. If the interval is smaller than the intervals shown in FIGS. 24-1 to 24-3, the optimum carrier frequency may increase or decrease due to measurement variation or the like. Therefore, it is not necessary to make the optimum carrier frequencies completely equal, but it is sufficient if they are made substantially equal.
- the present inventor has found that when a general semiconductor other than the wide band gap semiconductor is used as the switching element of the inverter 50 as the switching element, the optimum carrier frequency is determined regardless of the rotation speed and the torque of the motor M. For the first time. Further, as described in the first embodiment, it has been confirmed that the efficiency of the entire motor drive system can be maximized (loss can be minimized) by making the same for the other motor M and the inverter 50.
- the above-mentioned optimum carrier frequency can be derived, for example, by performing the processing of steps S1401 to S1408 and S1410 in the flowchart of FIG. If the optimum carrier frequency is (slightly) different according to the torque of the motor M, a representative value thereof (for example, an average value, a mode value, a median value, a minimum value, or a maximum value) is set as the optimum carrier frequency.
- a representative value thereof for example, an average value, a mode value, a median value, a minimum value, or a maximum value
- One may be derived for each rotation speed of M, or the relationship between the torque of the motor M and the optimum carrier frequency as described in the flow chart of FIG. The relationship that the carrier frequency becomes substantially the same value) may be derived for each rotation speed of the motor M.
- the carrier frequency set by the carrier frequency setting unit 75 for each rotation speed of the motor M regardless of the rotation speed and torque of the motor M has substantially the same value (for example, the minimum of the optimum carrier frequency). Value which is almost the same as the value). That is, in the present embodiment, in the actual use process, the carrier frequency setting unit 75 converts the optimum carrier frequency into an inverter based on the relationship that the optimum carrier frequency becomes substantially equal regardless of the torque and the rotation speed of the motor M.
- the carrier frequency at 50 is set for each rotation speed of the motor M.
- the inverter 50 having the switching element configured using a semiconductor other than the wide band gap semiconductor when used as the inverter 50, the carrier frequency is substantially reduced regardless of the rotation speed and the torque of the motor M. Be equal. Therefore, the same effect as that described in the first embodiment can be obtained even if a switching element configured using a general semiconductor other than the wide band gap semiconductor is used. Also in the present embodiment, various modifications described in the first embodiment can be adopted.
- the value of the rotation speed ratio of the motor M described above is merely an example, and the present invention is applicable to values other than the value of the rotation speed ratio of the motor M described above.
- the configuration of the control device 70 in the embodiment of the present invention described above can be realized by a computer executing a program. Further, a computer-readable recording medium on which the program is recorded and a computer program product such as the program can also be applied as an embodiment of the present invention.
- the recording medium for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
- the embodiments of the present invention described above are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. Things. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features.
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Abstract
Description
本願は、2018年7月2日に、日本に出願された特願2018-126066号に基づき優先権を主張し、その内容をここに援用する。
具体的に特許文献2では、モータの回転数が低く、且つ、モータのトルクが大きい第1の領域では、最も低い第1の周波数にキャリア周波数を設定する。また、モータの回転数が第1の領域で設定されている回転数よりも高く、且つ、モータのトルクが第1の領域で設定されているトルクと同程度である第2の領域では、第1の周波数よりも高い第2の周波数にキャリア周波数を設定する。また、モータの回転数が第1の領域および第2の領域で設定されている回転数よりも高く、且つ、モータのトルクが第1の領域および第2の領域で設定されているトルクよりも低い第2のトルクになる第3の領域では、最も高い第3の周波数にキャリア周波数を設定する。
本発明のモータ駆動システムの第2の例は、インバータと、前記インバータから交流電力の供給を受けて駆動されるモータと、前記インバータの動作を制御する制御装置とを有するモータ駆動システムであって、前記インバータは、ワイドバンドギャップ半導体以外の半導体を用いて構成されたスイッチング素子を有し、前記制御装置は、前記モータの回転数毎に導出される前記モータのトルクと前記インバータにおけるキャリア周波数との関係に基づいて、前記インバータのキャリア周波数を設定するキャリア周波数設定手段を有し、前記モータの回転数毎に導出される前記モータのトルクとキャリア周波数との関係は、前記モータのトルクに関わらず、キャリア周波数が略同等の値であることを特徴とする。
(第1の実施形態)
まず、第1の実施形態を説明する。
図1は、モータ駆動システムの概略構成の一例を示す図である。
本実施形態では、モータMが、回転子に永久磁石が内蔵されたIPMSM(Interior Permanent Magnet Synchronous Motor、永久磁石埋込型同期電動機)である場合を例に挙げて説明する。
整流回路20は、例えば4つのダイオードで構成された全波整流回路であり、交流電力を直流電力に変換するものである。
電解コンデンサ30は、整流回路20から出力された直流電力の脈流を除去するものである。
インバータ50は、例えば、三相フルブリッジを構成する6つのスイッチング素子を備えた回路である。インバータ50は、制御装置70から出力され、スイッチング素子に入力されるPWM信号Sに基づいて、スイッチング素子をオン・オフすることにより、入力した直流電力を、モータMを駆動するために必要な周波数を有する交流電力に変換し、モータMに出力(供給)する。本実施形態では、スイッチング素子が、ワイドバンドギャップ半導体(SiC、GaN等)を用いて構成されるスイッチング素子である場合を例に挙げて説明する。
印加電圧演算部71は、外部から入力する速度指令値(モータMの回転数の指令値)と、同じく外部から入力するトルク指令値(モータMのトルクの指令値)と、電圧センサ40で測定された入力電圧Viと、電流センサ61~63で測定されたモータ電流Iu、Iv、Iwとを入力し、これらに基づいて、モータMの各相に印加する電圧を演算し、その電圧を示す電圧指令信号を生成する。キャリア周波数設定装置7Aは、キャリア周波数設定部75を有する。
比較部73は、印加電圧演算部71で生成された電圧指令信号と、キャリア波発生部72で発生した三角波(キャリア波)とを比較する。
PWM信号出力部74は、比較部73における比較の結果に応じたパルス信号をPWM信号Sとしてインバータ50に出力する。前述したように、インバータ50は、このPWM信号Sに基づいてスイッチング素子をオン・オフして、入力した直流電力を交流電力に変換し、モータMに出力する。
インバータ50への入力電力からモータMの出力を減算した値が、モータ駆動システムで失われるエネルギー(損失)である。ここでは、この損失が、モータMの損失とインバータ50の損失との和に等しいものとして、損失の内訳を検討した。モータMの損失には鉄損および銅損の他に、機械損、風損、および軸受損等が含まれる。しかしながら、モータMの形状が同一で、回転数が同一であれば、インバータ50の動作が変更されても、これらの損失(機械損、風損、および軸受損等)は一定であると見なせる。従って、以下で示す鉄損は、これらの損失を含めたものとする。このようにしても、同一回転数であれば、モータMの損失の中に、これらの損失(機械損、風損、および軸受損等)が一定量含まれるものの、モータMのトルクの変化に対する、モータ駆動システムの損失の増減の傾向を検証するのに支障をきたさないと考えられる。そこで、ここでは、モータMの損失が鉄損(ただし、機械損、風損、および軸受損等を含めた損失)および銅損からなるものとした。また、ここでは、キャリア周波数の範囲を5kHz~50kHzとした。
・相数;3
・極数;12
・固定子外径;135mm
・固定子内径;87mm
・固定子スロット数;18(集中巻)
・固定子(コア)材質;無方向性電磁鋼板(35A300)
・回転子外径;85mm
・回転子(コア)積厚;30mm
・ロータ内の永久磁石の残留磁束密度1.1T
また、図2-1および図2-2において、銅損比率は、同一の回転数比率および同一のトルク比率の中でキャリア周波数fcが最低(ここでは5kHz)のときの総合損失に対する、各キャリア周波数fcでのモータMの銅損の比である。鉄損比率は、同一の回転数比率および同一のトルク比率の中でキャリア周波数fcが最低(ここでは5kHz)のときの総合損失に対する、各キャリア周波数fcでのモータMの鉄損の比である。インバータ損比率は、同一の回転数比率および同一のトルク比率の中でキャリア周波数fcが最低(ここでは5kHz)のときの総合損失に対する、各キャリア周波数fcでのインバータ50の損失の比である。
図3は、図2-1および図2-2に示す総合効率比率とキャリア周波数との関係をグラフ形式で示す図である。
図4-1および図4-2は、図2-1および図2-2に示す総合損失比率とキャリア周波数との関係をグラフ形式で示す図である。図4-1(a)、図4-1(b)、図4-1(c)、図4-2(a)、図4-2(b)は、それぞれ、トルク比率が、0.05、0.125、0.25、0.375、0.5(図2-1(a)、図2-1(b)、図2-1(c)、図2-2(a)、図2-2(b))のときの結果を示す。
キャリア周波数の5%程度の差異は総合損失が最小となる最適キャリア周波数の値に与える影響は小さい。従って、本明細書における「略同等」は、「キャリア周波数の差異が5%以下であること」を意味する。
さらに、モータMの回転数比率が何れの場合であっても、最低値の最適キャリア周波数に対応するトルク比率の範囲は、一つの範囲のみ存在することが分かる。例えば、モータMの回転数比率が0.75の場合には、トルク比率が0.05から0.125の範囲において、最適キャリア周波数が最低値の5kHzとなり、その他のトルク比率の範囲では、最適キャリア周波数の値は5kHzよりも高い。また、モータMの回転数比率が1.00の場合には、トルク比率が0.250において、最適キャリア周波数が最低値の20kHzとなり、その他のトルク比率の範囲では、最適キャリア周波数の値は20kHzよりも高い。よって、モータMのトルク比率が、最低の最適キャリア周波数に対応するトルク比率の範囲よりも小さい範囲では、モータMのトルク比率が大きくなると、最適キャリア周波数が、同じまたは低くなるようにすることにより、または、モータMのトルク比率が、最低の最適キャリア周波数に対応するトルク比率の範囲よりも大きい範囲では、モータMのトルク比率が大きくなると、最適キャリア周波数が、同じまたは高くなるようにすることにより、モータ駆動システム全体の効率を最大化(損失を最小化)することができる。
また、インバータ損比率と、鉄損比率および銅損比率の和の値そのものは、インバータやモータMの種類によって異なるが、キャリア周波数の変化に対する、インバータ損比率と、鉄損比率および銅損比率の和との変化の挙動は、モータMの種類によって大きく異なることはないと考えられる。従って、モータMのトルクが大きくなると、キャリア周波数が、略同等となるまたは高くなるようにすることにより、モータ駆動システム全体の効率を最大化(損失を最小化)することができることは、IPMSMに限らず、その他の種類のモータMであっても同じであると考えられる。
次に、ステップS1402において、制御装置70は、制御装置70に対して予め設定されているモータMのトルクの複数の候補のうち、未選択の候補を1つ指定する。
次に、ステップS1404において、制御装置70は、ステップS1401~S1403で指定された内容に基づいてPWM信号Sを生成し、インバータ50に出力する。インバータ50は、このPWM信号Sに基づいてモータMを動作させる。このとき、印加電圧演算部71は、ステップS1401で指定された回転数をモータMの回転数の指令値とし、ステップS1402で指定されたトルクをモータMのトルクの指令値として、モータMの各相に印加する電圧を演算し、その電圧を示す電圧指令信号を生成する。また、キャリア波発生部72は、ステップS1403で指定されたキャリア周波数の三角波を発生させる。
次に、ステップS1406において、制御装置70は、制御装置70に対して予め設定されているキャリア周波数の複数の候補を全て指定したか否かを判定する。この判定の結果、キャリア周波数の複数の候補を全て指定していない場合、処理は、ステップS1403に戻る。そして、キャリア周波数の複数の候補の全てが指定されるまで、ステップS1403~S1406の処理が繰り返し実行される。つまり、ステップS1405における総合損失の測定(導出)は、インバータ50におけるキャリア周波数を異ならせて行われる。
ステップS1407において、制御装置70は、ステップS1401で指定されたモータMの回転数、および、ステップS1402で指定されたモータMのトルクを指令値とするPWM信号Sを生成してモータMを駆動した場合の総合損失のうち最小の総合損失となるキャリア周波数を最適キャリア周波数として特定する(つまり、ステップS1405において導出された総合損失に基づいて、総合損失が最小になるときのキャリア周波数を最適キャリア周波数として導出する)。
ステップS1408においてモータMのトルクの複数の候補を全て指定したと判定される場合には、キャリア周波数の全ての候補のそれぞれの三角波を用いて、ステップS1401で指定されたモータMの回転数と、モータMのトルクの全ての候補のそれぞれとを指令値とするPWM信号Sを生成してモータMを駆動したときの最適キャリア周波数が、繰り返し実行されたステップS1407において得られている。そして、処理は、ステップS1409に進む。
ステップS1410においてモータMの回転数の複数の候補を全て指定したと判定される場合には、モータMの回転数の全ての候補のそれぞれについて、モータMのトルクと最適キャリア周波数との関係が、繰り返し実行されたステップS1409において得られている。そして、処理は、ステップS1411に進む。
「モータMのトルク比率が大きくなると、最適キャリア周波数が高くなる第1部分」には、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分」が含まれてもよい。
表1のモータMの回転数比率が「0.25」の例では、第1部分(モータMのトルク比率が0.050以上、1.000以下の部分)に、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分(モータMのトルク比率が0.050以上、0.125以下の部分、および、モータMのトルク比率が0.250以上、1.000以下の部分)」が含まれる。
表1のモータMの回転数比率が「0.50」の例では、第1部分(モータMのトルク比率が0.050以上、1.000以下の部分)に、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分(モータMのトルク比率が0.050以上、0.125以下の部分、および、モータMのトルク比率が0.250以上、1.000以下の部分)」が含まれる。
表1のモータMの回転数比率が「0.75」の例では、第1部分(モータMのトルク比率が0.050以上、0.750以下の部分)に、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分(モータMのトルク比率が0.050以上、0.125以下の部分、および、モータMのトルク比率が0.250以上、0.625以下の部分)」が含まれる。
「モータMのトルク比率が大きくなると、最適キャリア周波数が低くなる第2部分」には、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分」が含まれてもよい。
表1のモータMの回転数比率が「1.00」の例では、第2部分(モータMのトルク比率が0.050以上、0.250以下の部分)に、「モータMのトルク比率が大きくなっても最適キャリア周波数が略同等である部分(モータMのトルク比率が0.050以上、0.125以下の部分)」が含まれる。
モータMを駆動する際に、キャリア周波数設定部75は、モータMのトルクと最適キャリア周波数とのモータMの回転数毎の関係から、モータMのトルクの指令値およびモータMの回転数の指令値に対応する最適キャリア周波数を、インバータ50におけるキャリア周波数として抽出する(つまり、上述した関係に基づいて、モータMのトルクの指令値およびモータMの回転数の指令値に応じたキャリア周波数を設定する)。
例えば表1に示すモータMの回転数比率1.00におけるモータMのトルク比率と最適キャリア周波数との関係から、インバータ50におけるキャリア周波数が設定される場合、キャリア周波数設定部75は、モータMのトルクが最低の最適キャリア周波数(20kHz)に対応するモータMのトルク以上となる範囲(モータMのトルク比率が0.250~0.500の範囲)において、モータMのトルクが大きくなると20kHzから40kHzに高くなる最適キャリア周波数を、インバータ50におけるキャリア周波数として設定する。また、キャリア周波数設定部75は、モータMのトルクが最低の最適キャリア周波数(20kHz)に対応するモータMのトルク以下となる範囲(モータMのトルク比率が0.050~0.250の範囲)において、モータMのトルクが大きくなると40kHzから20kHzに低くなる最適キャリア周波数を、インバータ50におけるキャリア周波数として設定する。
キャリア波発生部72は、このようにしてキャリア周波数設定部75により設定されたキャリア周波数の三角波を発生させる。尚、以上のように、モータMのトルクと最適キャリア周波数とのモータMの回転数毎の関係における最適キャリア周波数の値は、インバータ50に適用するキャリア周波数として使用されるものである。従って、モータMのトルクと最適キャリア周波数とのモータMの回転数毎の関係は、モータMのトルクとインバータ50に適用するキャリア周波数とのモータMの回転数毎の関係と同義である。
次に、第2の実施形態を説明する。第1の実施形態では、インバータ50を構成するスイッチング素子が、ワイドバンドギャップ半導体を用いて構成されるスイッチング素子である場合を例に挙げて説明した。これに対し、本実施形態では、インバータ50を構成するスイッチング素子が、ワイドバンドギャップ半導体以外の半導体(一般的なバンドギャップを有する半導体)を用いて構成されるスイッチング素子である場合について説明する。このように、本実施形態と第1の実施形態とは、インバータ50を構成するスイッチング素子が異なることによる構成が主として異なる。従って、本実施形態の説明において、第1の実施形態と同一の部分については、図1~図14に付した符号と同一の符号を付す等して詳細な説明を省略する。
図15-1~図15-2は、モータMの回転数比率が1.00のときの損失の測定結果を表形式で示す図である。図15-1(a)、(b)、図15-2(a)、(b)は、それぞれ、図2-1(a)、(b)、図2-2(a)、(b)に対応する図である。図16は、図15-1および図15-2に示す総合効率比率とキャリア周波数との関係をグラフ形式で示す図である。図16は、図3に対応する図である。図17-1および図17-2は、図15-1および図15-2に示す総合損失比率とキャリア周波数との関係をグラフ形式で示す図である。図17-1(a)、(b)、(c)、図17-2(a)、(b)は、それぞれ、図4-1(a)、(b)、(c)、図4-2(a)、(b)に対応する図である。
図20-1~図20-3、図23-1~図23-3、図26-1~図26-3は、それぞれ、図18-1~図18-3、図21-1~図21-3、図24-1~図24-3に示す総合損失比率とキャリア周波数との関係をグラフ形式で示す図である。図20-1(a)、(b)、(c)~図20-3(a)、(b)、(c)、図23-1(a)、(b)、(c)~図23-3(a)、(b)、(c)、図26-1(a)、(b)、(c)~図26-3(a)、(b)、(c)は、それぞれ、図7-1(a)、(b)、(c)~図7-3(a)、(b)、(c)、図10-1(a)、(b)、(c)~図10-3(a)、(b)、(c)、図13-1(a)、(b)、(c)~図13-3(a)、(b)、(c)に対応する図である。
以上のことから、ワイドバンドギャップ半導体以外の半導体をスイッチング素子として用いると、モータMの回転数およびトルクによらず、最適キャリア周波数は略同等になる。
以上のように本発明者は、インバータ50のスイッチング素子として、ワイドバンドギャップ半導体以外の一般的な半導体をスイッチング素子として用いる場合には、モータMの回転数およびトルクによらず、最適キャリア周波数は、略同等になるという知見を初めて見出した。また、第1の実施形態で説明したように、他のモータMおよびインバータ50でも同様にすることで、モータ駆動システム全体の効率を最大化(損失を最小化)することができることを確認した。
つまり、本実施形態では、実使用工程において、キャリア周波数設定部75は、モータMのトルクおよび回転数に関わらず、最適キャリア周波数が略同等の値になる関係に基づいて、最適キャリア周波数をインバータ50におけるキャリア周波数としてモータMの回転数毎に設定する。
本実施形態においても、第1の実施形態で説明した種々の変形例を採用することができる。
上述したモータMの回転数比率の値は一例にすぎず、本発明は、上述したモータMの回転数比率の値以外の値にも適用可能である。
また、以上説明した本発明の実施形態は、何れも本発明を実施するにあたっての具体化の例を示したものに過ぎず、これらによって本発明の技術的範囲が限定的に解釈されてはならないものである。すなわち、本発明はその技術思想、またはその主要な特徴から逸脱することなく、様々な形で実施することができる。
Claims (9)
- モータを駆動するためのインバータにおけるキャリア周波数を設定するキャリア周波数設定方法であって、
前記インバータを用いて前記モータを駆動させた場合の前記インバータの損失と前記モータの損失との和である総合損失を導出することを、前記モータに生じるトルクと前記モータの回転数と前記インバータにおけるキャリア周波数とのそれぞれを異ならせて行う損失導出工程と、
前記損失導出工程により導出された前記総合損失に基づいて、複数のトルクおよび複数の回転数の組み合わせのそれぞれにおいて、前記総合損失が最小になるときのキャリア周波数を最適キャリア周波数として導出するキャリア周波数導出工程と、
前記キャリア周波数導出工程により導出された前記最適キャリア周波数に基づいて、前記モータのトルクと前記最適キャリア周波数との関係を、前記モータの回転数毎に導出する関係導出工程と、
前記関係導出工程により前記モータの回転数毎に導出された関係を記憶する関係記憶工程と、
前記関係記憶工程により前記関係が記憶された後、前記モータを駆動する際に、前記モータのトルクの指令値および前記モータの回転数の指令値に応じたキャリア周波数を、当該関係に基づいて設定するキャリア周波数設定工程と、
を有することを特徴とするキャリア周波数設定方法。 - 前記インバータは、ワイドバンドギャップ半導体を用いて構成されたスイッチング素子を有し、
前記関係導出工程で前記モータの回転数毎に導出される前記モータのトルクと前記最適キャリア周波数との関係は、前記モータのトルクが、前記キャリア周波数導出工程により導出された前記最適キャリア周波数のうち、最低のキャリア周波数に対応する前記モータのトルク以上となる範囲において、前記モータのトルクが大きくなると、前記最適キャリア周波数が高くなる第1部分を有することを特徴とする請求項1に記載のキャリア周波数設定方法。 - 前記関係導出工程で前記モータの回転数毎に導出される前記モータのトルクと前記最適キャリア周波数との関係は、前記モータのトルクが、前記キャリア周波数導出工程により導出された前記最適キャリア周波数のうち、最低のキャリア周波数に対応する前記モータのトルク以下となる範囲において、前記モータのトルクが大きくなると、前記最適キャリア周波数が低くなる第2部分を有することを特徴とする請求項2に記載のキャリア周波数設定方法。
- 前記関係導出工程で、前記モータの回転数毎に導出される前記モータのトルクと前記最適キャリア周波数との関係は、前記モータのトルクが、前記キャリア周波数導出工程により導出された前記モータの最適キャリア周波数のうち、最低のキャリア周波数に対応する前記モータのトルクの範囲を、一つのみ有することを特徴とする請求項2または3に記載のキャリア周波数設定方法。
- 前記インバータは、ワイドバンドギャップ半導体以外の半導体を用いて構成されたスイッチング素子を有し、
前記関係導出工程で前記モータの回転数毎に導出される前記モータのトルクと前記最適キャリア周波数との関係は、前記モータのトルクに関わらず、前記最適キャリア周波数が略同等の値であることを特徴とする請求項1に記載のキャリア周波数設定方法。 - インバータと、前記インバータから交流電力の供給を受けて駆動されるモータと、前記インバータの動作を制御する制御装置とを有するモータ駆動システムであって、
前記インバータは、ワイドバンドギャップ半導体を用いて構成されたスイッチング素子を有し、
前記制御装置は、前記モータの回転数毎に導出される前記モータのトルクと前記インバータにおけるキャリア周波数との関係に基づいて、前記インバータのキャリア周波数を設定するキャリア周波数設定手段を有し、
前記モータの回転数毎に導出される前記モータのトルクとキャリア周波数との関係は、前記モータのトルクが大きくなると、キャリア周波数が高くなる部分を有することを特徴とするモータ駆動システム。 - 前記モータの回転数毎に導出される前記モータのトルクとキャリア周波数との関係は、前記モータのトルクが、前記モータのトルクが大きくなるとキャリア周波数が高くなる部分の最低のキャリア周波数に対応する前記モータのトルク以下となる範囲において、前記モータのトルクが大きくなると、キャリア周波数が低くなる部分を有することを特徴とする請求項6に記載のモータ駆動システム。
- インバータと、前記インバータから交流電力の供給を受けて駆動されるモータと、前記インバータの動作を制御する制御装置とを有するモータ駆動システムであって、
前記インバータは、ワイドバンドギャップ半導体以外の半導体を用いて構成されたスイッチング素子を有し、
前記制御装置は、前記モータの回転数毎に導出される前記モータのトルクと前記インバータにおけるキャリア周波数との関係に基づいて、前記インバータのキャリア周波数を設定するキャリア周波数設定手段を有し、
前記モータの回転数毎に導出される前記モータのトルクとキャリア周波数との関係は、前記モータのトルクに関わらず、キャリア周波数が略同等の値であることを特徴とするモータ駆動システム。 - モータを駆動するためのインバータのキャリア周波数を設定するキャリア周波数設定装置であって、
前記キャリア周波数設定装置は、
前記モータのトルクと、前記インバータを用いて前記モータを駆動させた場合の前記インバータの損失と前記モータの損失との和である総合損失が最小になるときのキャリア周波数である最適キャリア周波数との関係として、
前記インバータが、ワイドバンドギャップ半導体を用いて構成されたスイッチング素子を有する場合に、前記モータのトルクが、前記最適キャリア周波数が最低値となるキャリア周波数に対応する前記モータのトルク以上となる範囲において、前記モータのトルクが大きくなると、前記最適キャリア周波数が高くなる部分を有し、前記モータのトルクが、前記最適キャリア周波数が最低値となるキャリア周波数に対応する前記モータのトルク以下となる範囲において、前記モータのトルクが大きくなると、前記最適キャリア周波数が低くなる部分を更に有する関係を、前記モータの回転数毎に導出し、
前記インバータが、前記ワイドバンドギャップ半導体以外の半導体を用いて構成された前記スイッチング素子を有する場合に、前記モータのトルクに関わらず、前記最適キャリア周波数が略一定値である関係を、前記モータの回転数毎に導出し、
前記モータのトルクと前記最適キャリア周波数との関係に基づいて、前記インバータのキャリア周波数を設定することを特徴とするキャリア周波数設定装置。
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JP2009171768A (ja) | 2008-01-17 | 2009-07-30 | Toyota Motor Corp | 電動車両の制御装置およびそれを備えた電動車両、ならびに電動車両の制御方法およびその制御方法をコンピュータに実行させるためのプログラムを記録したコンピュータ読取可能な記録媒体 |
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JP2012010513A (ja) * | 2010-06-25 | 2012-01-12 | Nippon Steel Corp | モータ駆動装置 |
JP2018074786A (ja) * | 2016-10-31 | 2018-05-10 | 三菱電機株式会社 | 電力変換装置 |
JP2018126066A (ja) | 2017-02-06 | 2018-08-16 | 不二製油株式会社 | 餌用生物用油脂組成物、餌用生物用油脂組成物の製造方法及び餌用生物の製造方法 |
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CN111293953A (zh) * | 2020-03-27 | 2020-06-16 | 重庆金康动力新能源有限公司 | 电机控制方法、装置、电动汽车和存储介质 |
WO2023007619A1 (ja) * | 2021-07-28 | 2023-02-02 | 三菱電機株式会社 | 電力変換装置および空気調和機 |
JP7515727B2 (ja) | 2021-07-28 | 2024-07-12 | 三菱電機株式会社 | 電力変換装置および空気調和機 |
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EP3820039A1 (en) | 2021-05-12 |
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TW202019081A (zh) | 2020-05-16 |
US11888422B2 (en) | 2024-01-30 |
BR112020022425A2 (pt) | 2021-02-09 |
TWI713296B (zh) | 2020-12-11 |
CA3097504C (en) | 2023-03-28 |
KR102580048B1 (ko) | 2023-09-20 |
CA3097504A1 (en) | 2020-01-09 |
CN112219351B (zh) | 2024-02-09 |
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EP3820039A4 (en) | 2022-03-23 |
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KR20210003870A (ko) | 2021-01-12 |
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