WO2012133887A1 - Electric power conversion device for driving motor - Google Patents

Electric power conversion device for driving motor Download PDF

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Publication number
WO2012133887A1
WO2012133887A1 PCT/JP2012/058890 JP2012058890W WO2012133887A1 WO 2012133887 A1 WO2012133887 A1 WO 2012133887A1 JP 2012058890 W JP2012058890 W JP 2012058890W WO 2012133887 A1 WO2012133887 A1 WO 2012133887A1
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WIPO (PCT)
Prior art keywords
motor
phase
voltage
control unit
frequency
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PCT/JP2012/058890
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French (fr)
Japanese (ja)
Inventor
健太 塚越
孝英 小澤
正和 駒井
希美 畑林
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株式会社 荏原製作所
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Publication of WO2012133887A1 publication Critical patent/WO2012133887A1/en

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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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details
    • H02P1/04—Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter
    • 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
    • H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
    • 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

Definitions

  • the present invention relates to a power converter capable of driving a motor without using a rotor position sensor.
  • Permanent magnet synchronous motors are widely used in various fields because they are highly efficient and maintenance-free. In order to drive this permanent magnet synchronous motor at a variable speed, it is necessary to detect the rotational position of the rotor. Conventionally, various methods for driving a permanent magnet synchronous motor without using a rotor position sensor have been developed. For example, in the methods disclosed in Patent Document 1 and Patent Document 2, the position of the rotor is estimated from the induced voltage generated in the winding of the motor, and the current flowing through the motor is controlled.
  • the situation of starting the motor includes not only the case of starting the motor in a stopped state but also the case of starting a motor that is freely rotating by inertia or external energy.
  • the impeller may rotate as a water wheel by the liquid flowing in the pump.
  • the starting operation of the pump in such a situation is an operation of starting a motor that is freely rotating.
  • ⁇ Motor free rotation also occurs during momentary power outages. That is, the motor immediately after the power failure continues to rotate for a while due to inertia. Therefore, the operation for starting the motor immediately after the momentary power failure is also the operation for starting the freely rotating motor.
  • Patent Document 3 discloses a water supply device using a brushless DC motor for driving a pump.
  • the rotational speed of the rotor rotated by the water flowing through the pump is monitored, and the motor is started by synchronizing the rotational speed of the rotor with the target rotational speed.
  • the water supply apparatus described in the cited document 3 uses a sensor for detecting the position of the rotor, the motor becomes expensive.
  • Patent Document 4 describes a method of starting a freely rotating motor without using a rotor position sensor. This method determines the phase and rotational speed of the motor based on the intersection of the U-phase and V-phase of the induced voltage generated in the rotating motor.
  • the induced voltage increases when the rotational speed of the motor is high. Therefore, it is relatively easy to determine the intersection between the U phase, V phase, and W phase of the induced voltage.
  • the rotational speed of the motor is low, the induced voltage becomes small as shown in FIG. For this reason, it becomes difficult to determine the intersections between the U phase, the V phase, and the W phase due to the influence of noise appearing in the waveform of the induced voltage of each phase.
  • an accurate phase and rotation speed of the motor cannot be obtained, and the inverter cannot start motor driving synchronized with the actual rotation speed of the motor.
  • a comparator with hysteresis or a chattering prevention filter can be adopted.
  • processing using these hardware or software delays accurate phase detection.
  • the present invention has been made to solve the above-described conventional problems, and provides a power conversion device for driving a motor capable of accurately detecting the phase and rotation speed of the motor to perform synchronous start of the motor.
  • the purpose is to do.
  • one aspect of the present invention is a power conversion device for driving a motor, which includes a voltage measuring device for measuring an induced voltage of the motor, and power having a variable frequency for the motor.
  • Another aspect of the present invention is a power conversion device for driving a motor, wherein the voltage measuring device measures an induced voltage of the motor, an inverter that supplies electric power of variable frequency to the motor, A vector control unit that controls output power; and a synchronous start control unit that determines a phase and a rotational speed of the motor from the measured induced voltage, and the synchronous start control unit includes the determined rotational speed of the motor. Is converted into a frequency to obtain an estimated frequency, an output frequency is calculated from the induced voltage and a proportional constant V / f specific to the motor, and a difference between the output frequency and the estimated frequency is equal to or greater than a predetermined value.
  • the phase and rotational speed of the determined motor are discarded, and when the difference between the output frequency and the estimated frequency is smaller than the predetermined value, the determined mode is determined. And wherein the sending the phase and the rotational speed of the motor to the vector control unit.
  • Still another aspect of the present invention is a power conversion device for driving a motor, a voltage measuring device for measuring an induced voltage of the motor, an inverter for supplying variable frequency power to the motor, and the inverter
  • a vector control unit that controls output power of the motor, and a synchronous start control unit that determines the phase and rotation speed of the motor from the measured induced voltage, and the synchronous start control unit includes the determined rotation of the motor.
  • the speed is converted into a frequency
  • an estimated voltage is calculated from the obtained motor frequency and a proportional constant V / f specific to the motor, and the difference between the induced voltage and the estimated voltage is a predetermined value or more.
  • the phase and speed of the determined motor are discarded, and the difference between the induced voltage and the estimated voltage is smaller than the predetermined value, the phase and speed of the determined motor are determined. And wherein the sending rate to the vector control unit.
  • the motor can be started by supplying electric power synchronized with the phase and rotational speed of the freely rotating motor.
  • FIG. 5 It is a figure which shows the induced voltage of a motor when the rotational speed of a motor is high. It is a figure which shows the induced voltage of a motor when the rotational speed of a motor is low. It is a block diagram which shows the power converter device which concerns on one Embodiment of this invention. It is a block diagram of an inverter control part. It is a block diagram which shows the synchronous starting control part shown in FIG. 5 is a graph showing a U-phase, V-phase, and W-phase voltage signal, a pulse signal P UV indicating a line voltage in the U-V phase, and a pulse signal P VW indicating a line voltage in the V-W phase.
  • FIG. 3 is a block diagram showing a power converter according to an embodiment of the present invention.
  • the power converter 5 is used to drive a motor M connected to the pump P.
  • the power conversion device 5 includes an inverter 10, a sensor unit 15, an inverter control unit 16, a storage unit 17, and an operation communication unit 19.
  • the inverter 10 has a converter circuit 11, an inverter circuit 12, and a gate drive circuit 13.
  • the converter circuit 11 has a rectifier circuit, and is configured to convert three-phase AC power supplied from the commercial power source 1 into DC power.
  • the inverter circuit 12 includes a switching element such as an IGBT (insulated gate bipolar transistor), and generates three-phase AC power from the DC power converted by the converter circuit 11.
  • the gate drive circuit 13 generates a gate drive signal for opening and closing each switching element of the inverter circuit 12.
  • the switching element of the inverter circuit 12 is driven in accordance with a gate drive signal from the gate drive circuit 13, and the inverter circuit 12 thereby outputs AC power having a variable frequency.
  • the sensor unit 15 has a current measuring device 20 and a voltage measuring device 21.
  • the current measuring device 20 measures the three-phase current output from the inverter circuit 12 and sends the measured value (output current signal) to the inverter control unit 16.
  • the voltage measuring device 21 measures the induced voltage generated by the motor M and sends the measured value (induced voltage signal) to the inverter control unit 16.
  • the sensor unit 15 may further include various sensors that measure a control target such as the discharge pressure and flow rate of the pump P.
  • Reference numeral 25 in FIG. 3 is a pressure sensor for measuring the discharge pressure of the pump P.
  • the storage unit 17 is a non-volatile memory and stores various parameters necessary for driving and controlling the inverter circuit 12, a control program, and the like.
  • the storage unit 17 stores programs and various parameters necessary for pump operation control such as discharge pressure control.
  • the operation communication unit 19 is configured to start and stop the operation of the power conversion device 5 and set various setting values by an operation from the outside of the power conversion device 5. Moreover, the operation communication part 19 receives a frequency command signal from the outside, and outputs the signal which shows a driving condition outside. The operation communication unit 19 may be configured to connect to a higher-level control device via communication.
  • the inverter control unit 16 controls the rotation speed of the motor M based on the measurement signal sent from the sensor unit 15 and the frequency command signal sent from the operation communication unit 19. That is, the inverter control unit 16 receives the frequency command signal from the operation communication unit 19 and generates a PWM signal based on the measurement signal from the sensor unit 15. This PWM signal is sent to the gate drive circuit 13.
  • the gate drive circuit 13 generates a gate drive signal for driving the switching element of the inverter circuit 12 based on the PWM signal.
  • the switching element of the inverter circuit 12 is driven in accordance with a gate drive signal from the gate drive circuit 13, and the inverter circuit 12 thereby outputs AC power having a variable frequency.
  • FIG. 4 is a block diagram of the inverter control unit 16.
  • the inverter control unit 16 decomposes the current supplied to the motor M into a torque current component and a magnetizing current component and independently controls them, and a phase of the motor M from an induced voltage generated in the motor M.
  • a synchronous start control unit 50 for determining the rotation speed. Since the synchronous start control unit 50 can determine the rotation speed of the freely rotating motor M, the vector control unit 30 can start the inverter drive synchronized with the rotation speed of the motor M.
  • the three-phase output current of the inverter 10 is measured by the current measuring device 20.
  • the measured three-phase currents Iu, Iv, and Iw are converted into two-phase currents Id and Iq on the rotating coordinate system by the 3 / 2-phase converting unit 32 and the stationary / rotating coordinate converting unit 33, and then the magnetization voltage control is performed.
  • the magnetizing voltage control unit 34 obtains a magnetizing voltage command value Vd * in which the deviation between the magnetizing current Id and the magnetizing current command value Id * is 0 by PI calculation.
  • the magnetizing current command value Id * is an ideal magnetizing current calculated using a motor model.
  • the torque voltage control unit 35 obtains a torque voltage command value Vq * in which a deviation between the torque current Iq and the torque current command value Iq * is 0 by PI calculation.
  • the target torque current determination unit 37 performs the PI calculation so that the difference between the angular velocity command value ⁇ * input from the outside and the current angular velocity ⁇ becomes zero, and determines the torque current command value Iq *.
  • the current angular velocity ⁇ is obtained by an axis error estimator (PLL) 38 based on the voltage command values Vd * and Vq *.
  • the phase ⁇ is obtained from the angular velocity ⁇ by the integrator 39.
  • the obtained phase ⁇ is sent to the stationary / rotational coordinate converter 33 and the rotational / static coordinate converter 40.
  • the voltage command values Vd * and Vq * are converted into the three-phase voltage command values Vu *, Vv * and Vw * on the fixed coordinate system via the rotation / stationary coordinate conversion unit 40 and the 2/3 phase conversion unit 41.
  • the vector control unit 30 generates a PWM signal corresponding to these three-phase voltage command values Vu *, Vv *, Vw *, and sends this PWM signal to the gate drive circuit 13.
  • the gate drive circuit 13 generates a gate drive circuit PWM signal based on the PWM signal corresponding to the three-phase voltage command values Vu *, Vv *, Vw *, and the switching element operates based on the gate drive circuit PWM signal ( On, off).
  • the inverter 10 generates a voltage based on the three-phase voltage command value from the vector control unit 30 and applies it to the motor M.
  • water supply may be performed by the pressure of the liquid from the water main even when the pump is stopped. Accordingly, even when the motor M is not driven by the inverter 10, the pump impeller and the motor M connected thereto are rotated by the liquid flowing in the pump. Thus, in order to start the motor M by the inverter 10 from the state where the motor M is freely rotating, it is necessary for the inverter 10 to generate a voltage synchronized with the frequency and phase of the induced voltage of the rotating motor M. is there.
  • the free rotation of the motor M also occurs immediately after an instantaneous power failure. That is, if a momentary power failure occurs while the motor M is being driven by the inverter 10, even if no power is supplied to the motor M, the rotor of the motor M continues to rotate for a while due to inertia. When starting the freely rotating motor M after the power failure is restored, the inverter 10 needs to generate a voltage synchronized with the frequency and phase of the induced voltage of the motor M.
  • a state in which the motor is rotated by external kinetic energy or inertia without being supplied with electric power is referred to as “free rotation”.
  • the power converter 5 measures the induced voltages of the U phase, V phase, and W phase of the motor M, and the measurement is performed.
  • the phase (magnetic pole position) and rotation speed of the motor that is freely rotating are estimated from the voltage, and control of the inverter 10 is started based on the estimated phase and rotation speed.
  • FIG. 5 is a block diagram showing the synchronous start control unit 50 shown in FIG. As shown in FIG. 5, the synchronous start control unit 50 includes a first line voltage comparator 51A that generates a pulse signal from the voltage difference between the U phase and the V phase, and a pulse signal from the voltage difference between the V phase and the W phase.
  • the voltage measuring device 21 measures the voltage of the three-phase line connecting the inverter 10 and the motor M, and outputs U-phase, V-phase, and W-phase voltage signals.
  • This three-phase output voltage signal is a signal indicating the induced voltage of the freely rotating motor M.
  • the output voltage signal is amplified by the gain adjuster 49 and then sent to the first line voltage comparator 51A, the second line voltage comparator 51B, and the AD converter 55a of the speed calculation unit 55.
  • the first line voltage comparator 51A compares the U-phase voltage signal with the V-phase voltage signal to generate a pulse signal PUV . Specifically, a high-level signal is generated when the V-phase voltage signal is higher than the U-phase voltage signal, and a low-level signal is generated when the V-phase voltage signal is lower than the U-phase voltage signal.
  • the second line voltage comparator 51B compares the V-phase voltage signal and the W-phase voltage signal to generate a pulse signal PVW . That is, a high level signal is generated when the W phase voltage signal is higher than the V phase voltage signal, and a low level signal is generated when the W phase voltage signal is lower than the V phase voltage signal.
  • FIG. 6 is a graph showing U-phase, V-phase, and W-phase voltage signals, a pulse signal P UV indicating the line voltage of the U-V phase, and a pulse signal P VW indicating the line voltage of the V-W phase. It is. As can be seen from the graph, the pulse signal P UV rising edge E1 and the falling edge E2 is manifested in that the voltage signal of the voltage signal and the V-phase of the U-phase crossing, rising edge E3 and falling of the pulse signal P VW The falling edge E4 appears at the point where the V-phase voltage signal and the W-phase voltage signal intersect.
  • the pulse signal P UV and the pulse signal P VW generated by the line voltage comparators 51A and 51B are sent to the first pulse edge detector 52A and the second pulse edge detector 52B, respectively.
  • First pulse edge detection unit 52A each time detects the pulse signal P UV rising edge E1 and the falling edge E2, these rising edges E1 and falling edge E2 is detected, the speed calculated pulse edge detection signal Send to part 55.
  • the second pulse edge detector 52B detects the rising edge E3 and the falling edge E4 of the pulse signal PVW , and each time the rising edge E3 and the falling edge E4 are detected, the pulse edge detection signal Is sent to the speed calculation unit 55.
  • FIG. 6 shows that four pulse edges E1, E2, E3, and E4 appear within one cycle of the induced voltage of the motor.
  • the speed calculation unit 55 When receiving the pulse edge detection signal from the first pulse edge detection unit 52A or the second pulse edge detection unit 52B, the speed calculation unit 55 specifies the phase of the motor M and the angular frequency ( That is, the calculation of the rotational speed scalar quantity) is started.
  • FIG. 7 is a diagram illustrating a flowchart for calculating an angular frequency (rotational speed) of a motor that is freely rotating.
  • the speed calculation unit 55 acquires the current time t n .
  • the speed calculation unit 55 identifies the phase (angle) ⁇ n of the detected pulse edge, and sends the phase ⁇ n of the motor at time t n to the integrator 39 of the vector control unit 30.
  • the phase ⁇ n is set in advance for each pulse edge that appears within one cycle of the induced voltage.
  • the phase of the pulse edge E1 is set to 5 / 6 ⁇
  • the phase of the pulse edge E2 is set to ⁇ 1 / 6 ⁇
  • the phase of the pulse edge E3 is set to ⁇ 1 / 2 ⁇
  • the phase of the pulse edge E4 is set to 1 / 2 ⁇ .
  • the speed calculation unit 55 sends 5 / 6 ⁇ to the integrator 39 as the phase ⁇ n of the motor. Similarly, if the detected pulse edge is the pulse edge E2, the speed calculation unit 55 sends ⁇ 1 / 6 ⁇ to the integrator 39 as the phase ⁇ n of the motor. If the detected pulse edge is the pulse edge E3, the speed calculation unit 55 sends -1 / 2 ⁇ to the integrator 39 as the phase ⁇ n of the motor. If the detected pulse edge at the pulse edge E4, the speed calculation portion 55 sends the 1/2 [pi as the phase theta n of the motor to the integrator 39.
  • the integrator 39 When the phase theta n is input, the integrator 39 resets the phase theta phase theta n (replacing the phase theta phase theta n), the phase theta n stationary / rotating coordinate conversion section 33 and a rotating / stationary coordinate converter Send to part 40.
  • the speed calculation unit 55 uses the elapsed time ⁇ t since the previous pulse edge was detected, the current phase ⁇ n, and the phase ⁇ n ⁇ 1 when the previous pulse edge was detected.
  • the angular frequency ⁇ n of the freely rotating motor is determined as follows. In this way, the phase ⁇ n and the angular frequency ⁇ n of the freely rotating motor are determined.
  • the three-phase voltage shown in FIG. 6 has a relatively large amplitude.
  • the induced voltage becomes small as shown in FIG.
  • the pulse signal determined from the intersection between the U phase, the V phase, and the W phase becomes unstable due to the influence of noise appearing in the voltage waveform of each phase.
  • an accurate phase and rotation speed of the motor cannot be obtained.
  • FIG. 8 is a flowchart showing the synchronous start operation of the motor. If a pulse edge is detected while the inverter 10 is stopped (step 1), the timer is reset to 0 and the timer is started (step 2). The measured value of the motor output voltage (induced voltage) is taken from the voltage measuring device 21 to the speed calculation unit 55 via the AD converter 55a and compared with a preset threshold value (step 3).
  • the angular frequency ⁇ n and the phase ⁇ n are discarded, and the angular frequency ⁇ n and the phase ⁇ n are both set to 0 (step 5). Then, the angular frequency ⁇ n and the phase ⁇ n set to 0 are sent to the vector control unit 30 (step 6).
  • the angular frequency ⁇ n is calculated using the above equation (1), and the phase ⁇ n is specified based on the detected pulse edge (Ste 4). Thereafter, the obtained angular frequency ⁇ n and phase ⁇ n are sent to the vector control unit 30 (step 6).
  • the vector control unit 30 determines whether or not an operation command is input from the outside (step 7), and when the operation command is not input, the process flow returns to step 1.
  • the motor is started in synchronization with the speed of the freely rotating motor (step 8).
  • the angular frequency ⁇ n and the phase ⁇ n are calculated in step 4 after determining whether the output voltage of the motor is larger than the threshold value in step 3, but the order of step 3 and step 4 is calculated. May be replaced, and the angular frequency ⁇ n and the phase ⁇ n may be calculated first, and then it may be determined whether or not the motor output voltage is greater than the threshold value.
  • the switch SW1 shown in FIG. 4 is connected to the axis error estimator 38 and the synchronous start control unit 50.
  • the angular frequency ⁇ C from the axis error estimator 38 and the angular frequency ⁇ n from the synchronous start control unit 50 Only one of them is selectively passed. Therefore, as the angular frequency ⁇ input to the target torque current determining unit 37 and the integrator 39, either the angular frequency ⁇ C or the angular frequency ⁇ n is employed.
  • the synchronous start control unit 50 and the vector control unit 30 are connected via the switch SW1, and the angular frequency ⁇ n from the synchronous start control unit 50 is determined as the vector control unit. 30 continues to be input.
  • the angular frequency omega C from the axis error estimator 38 is sent to the target torque current determination unit 37 and the integrator 39 via the switch SW1, the vector control is performed.
  • step 9 the timer is reset (step 9), and the angular frequency ⁇ n and the phase ⁇ n are both set to 0 (step 5). ).
  • the obtained angular frequency ⁇ n and phase ⁇ n are discarded, and the angular frequency ⁇ n and phase ⁇ n are set to 0 (step 5). reference).
  • the noise appearing in the motor output voltage waveform is considered to have generated a pulse edge due to the small induced voltage of the motor. That is, the actual rotational speed and phase of the motor cannot be determined from the pulse edge generated due to noise.
  • the calculated angular frequency ⁇ n and the specified phase ⁇ n are sent to the vector control unit 30 (see step 4).
  • the angular frequency ⁇ n is input to the target torque current determination unit 37 and the integrator 39 via the switch SW1, and the phase ⁇ n is input to the rotation / stationary coordinate conversion unit 40 and the stationary / rotation coordinate conversion unit 33 via the integrator 39. Is input. Then, the vector control unit 30 generates voltage command values Vu *, Vv *, Vw * synchronized with the phase and rotation speed of the freely rotating motor M. The inverter 10 outputs electric power according to the voltage command values Vu *, Vv *, Vw *, and starts the motor M (step 8). In this manner, the power conversion device 5 can start the motor in a state where the frequency and phase of the output voltage of the inverter 10 are synchronized with the frequency and phase of the output voltage of the freely rotating motor.
  • the process flow cannot proceed to step 4 and the motor cannot be started synchronously. Therefore, as described above, when the time measured by the timer exceeds a preset time, the motor is started assuming that the angular frequency ⁇ n is 0 (see steps 9 and 5 in FIG. 8). ). Specifically, if the pulse edge is not detected within a predetermined time, the angular frequency ⁇ n is set to zero. By incorporating such processing steps into the processing flow, the motor is started even when the rotational speed of the motor is zero or very low.
  • the rotation direction of the motor can be determined from the order in which the pulse edges appear. Specifically, when the motor is rotating in the forward direction, pulse edges appear in the order of E1, E3, E2, and E4. On the other hand, specifically, when the motor rotates in the reverse direction, pulse edges appear in the order of E4, E2, E3, and E1. Therefore, the speed calculation unit 55 can determine the rotation direction of the motor from the order of the pulse edges.
  • FIG. 9 is a graph showing the U-phase and V-phase voltage signals and the pulse signal P UV indicating the line voltage of the U-V phase.
  • the phase ⁇ n can be specified from the pulse edges E1 and E2, and the angular frequency ⁇ n can be calculated using the above equation (1).
  • FIG. 10 is a flowchart showing another embodiment of the synchronous start operation of the motor.
  • the angular frequency ⁇ n is calculated using the above equation (1), and the phase ⁇ n is specified based on the detected pulse edge.
  • the angular frequency ⁇ frequency is determined from n f n (hereinafter, referred to as estimated frequency f n) and the frequency f i of the motor output voltage (induced voltage) (hereinafter, referred to as the output frequency f i) and Based on the difference between them, the calculated angular frequency ⁇ n and phase ⁇ n are discarded, and the speed calculation unit 55 determines whether or not to set them to 0. Steps other than steps 3 and 4 are the same as the steps shown in FIG.
  • the output frequency f i can be obtained from the measured value of the output voltage of the motor input to the AD converter 55a and the known proportionality constant V / f.
  • the output frequency f i can be obtained by dividing the measured value of the output voltage of the motor by the proportionality constant V / f.
  • This proportional constant V / f is a constant inherent to the motor, and is obtained by dividing the rated voltage of the motor by the rated frequency of the motor.
  • the absolute value (magnitude) of the difference between the estimated frequency f n and the output frequency f i is compared with a predetermined value (step 4). If the absolute value of the difference between the estimated frequency f n and the output frequency f i is greater than or equal to a predetermined value, the calculated angular frequency ⁇ n and phase ⁇ n are discarded, and the angular frequency ⁇ n and phase ⁇ n are It is set to 0 (step 5). Then, the angular frequency ⁇ n and the phase ⁇ n set to 0 are sent to the vector control unit 30 (step 6).
  • the calculated angular frequency ⁇ n and the specified phase ⁇ n are sent to the vector control unit 30.
  • the vector control unit 30 generates voltage command values Vu *, Vv *, Vw * to the inverter 10 based on the angular frequency ⁇ n and the phase ⁇ n .
  • the inverter 10 outputs a voltage synchronized with the phase and frequency of the induced voltage of the freely rotating motor to the motor.
  • FIG. 11 is a flowchart showing still another embodiment of the synchronous start operation of the motor.
  • the angular frequency ⁇ n is calculated using the above equation (1), and the phase ⁇ n is specified based on the detected pulse edge.
  • the estimated voltage V n obtained from the angular frequency omega n based on the difference between the output voltage V i of the motor that is input to the AD converter 55a, the angular frequency is calculated omega n and phase ⁇
  • the speed calculator 55 determines whether to discard n and set them to 0. Steps other than steps 3 and 4 are the same as the steps shown in FIG.
  • the absolute value (magnitude) of the difference between the estimated voltage V n and the output voltage V i is compared with a predetermined value (step 4). If the absolute value (magnitude) of the difference between the estimated voltage V n and the output voltage V i is greater than or equal to a predetermined value, the calculated angular frequency ⁇ and phase ⁇ n are discarded, and the angular frequency ⁇ n and phase ⁇ n is set to 0 (step 5). Then, the angular frequency ⁇ n and the phase ⁇ n set to 0 are sent to the vector control unit 30 (step 6).
  • the calculated angular frequency ⁇ n and the specified phase ⁇ n are sent to the vector control unit 30.
  • the vector control unit 30 generates voltage command values Vu *, Vv *, Vw * to the inverter 10 based on the angular frequency ⁇ n and the phase ⁇ n .
  • the inverter 10 outputs a voltage synchronized with the phase and frequency of the induced voltage of the freely rotating motor to the motor.
  • the present invention can be applied to a power converter that can drive a motor without using a rotor position sensor.

Abstract

An electric power conversion device is provided with a voltage measurement device (21) for measuring the induced voltage of a motor (M); an inverter (10) for supplying electric power with a variable frequency to the motor (M); a vector control unit (30) for controlling the output electric power of the inverter (10); and a synchronous start control unit (50) for determining the phase and rotational speed of the electric motor (M) from the induced voltage. When the induced voltage is lower than or equal to a predetermined value, the synchronous start control unit (50) discards the determined phase and rotational speed of the motor (M), and when the induced voltage is higher than the predetermined value, the synchronous start control unit (50) sends the determined phase and rotational speed of the motor (M) to the vector control unit (30).

Description

モータ駆動用の電力変換装置Power converter for motor drive
　本発明は、ロータの位置センサを用いることなく、モータを駆動することができる電力変換装置に関する。 The present invention relates to a power converter capable of driving a motor without using a rotor position sensor.
　永久磁石同期モータは、高効率かつメンテナンスフリーであることから、様々な分野に広く使用されている。この永久磁石同期モータを可変速駆動するためには、ロータの回転位置を検出することが必要となる。従来から、ロータの位置センサを使用せずに永久磁石同期モータを駆動するための様々な方法が開発されている。例えば、特許文献１および特許文献２に開示されている方法では、モータの巻線に生じる誘起電圧からロータの位置を推定し、モータに流す電流を制御する。 Permanent magnet synchronous motors are widely used in various fields because they are highly efficient and maintenance-free. In order to drive this permanent magnet synchronous motor at a variable speed, it is necessary to detect the rotational position of the rotor. Conventionally, various methods for driving a permanent magnet synchronous motor without using a rotor position sensor have been developed. For example, in the methods disclosed in Patent Document 1 and Patent Document 2, the position of the rotor is estimated from the induced voltage generated in the winding of the motor, and the current flowing through the motor is controlled.
　モータを始動する状況には、停止している状態のモータを始動する場合のみならず、慣性または外部エネルギーにより自由回転しているモータを始動する場合も含まれる。例えば、モータをポンプの駆動に使用する場合、モータが停止しているときでも、ポンプ内を流れる液体により羽根車が水車としてモータを回転させることがある。このような状況でのポンプの始動動作は、自由回転しているモータを始動させる動作である。 The situation of starting the motor includes not only the case of starting the motor in a stopped state but also the case of starting a motor that is freely rotating by inertia or external energy. For example, when a motor is used for driving a pump, even when the motor is stopped, the impeller may rotate as a water wheel by the liquid flowing in the pump. The starting operation of the pump in such a situation is an operation of starting a motor that is freely rotating.
　モータの自由回転は、瞬間的な停電時にも起こる。すなわち、停電の直後のモータは、慣性によりしばらくは回転し続ける。したがって、瞬間的な停電の直後にモータを始動させる動作も、自由回転しているモータを始動させる動作となる。 ¡Motor free rotation also occurs during momentary power outages. That is, the motor immediately after the power failure continues to rotate for a while due to inertia. Therefore, the operation for starting the motor immediately after the momentary power failure is also the operation for starting the freely rotating motor.
　特許文献３には、ブラシレスＤＣモータをポンプの駆動に使用した給水装置が開示されている。この給水装置では、ポンプを流通する水により回転するロータの回転速度を監視し、ロータの回転速度を目標回転速度と同期させてモータを始動する。しかしながら、この引用文献３に記載の給水装置は、ロータの位置を検出するセンサが使用されているため、モータが高価となってしまう。 Patent Document 3 discloses a water supply device using a brushless DC motor for driving a pump. In this water supply apparatus, the rotational speed of the rotor rotated by the water flowing through the pump is monitored, and the motor is started by synchronizing the rotational speed of the rotor with the target rotational speed. However, since the water supply apparatus described in the cited document 3 uses a sensor for detecting the position of the rotor, the motor becomes expensive.
　特許文献４には、ロータの位置センサを用いることなく、自由回転しているモータを始動する方法が記載されている。この方法は、回転するモータに発生する誘起電圧のＵ相およびＶ相の交差点に基づいて、モータの位相および回転速度を決定する。 Patent Document 4 describes a method of starting a freely rotating motor without using a rotor position sensor. This method determines the phase and rotational speed of the motor based on the intersection of the U-phase and V-phase of the induced voltage generated in the rotating motor.
特開平３－１５５３９３号公報Japanese Patent Laid-Open No. 3-155393 特開平５－８３９６５号公報JP-A-5-83965 特開２００１－５０１６８号公報Japanese Patent Laid-Open No. 2001-50168 特開２００５－１３７１０６号公報JP 2005-137106 A
　図１に示すように、モータの回転速度が高いときには、誘起電圧は大きくなる。したがって、誘起電圧のＵ相、Ｖ相、Ｗ相間の交差点を決定することは比較的容易である。しかしながら、モータの回転速度が低いときは、図２に示すように、誘起電圧は小さくなる。このため、各相の誘起電圧の波形に現れるノイズの影響で、Ｕ相、Ｖ相、Ｗ相間の交差点を決定することが困難となる。結果として、モータの正確な位相や回転速度が得られなく、インバータはモータの実際の回転速度に同期したモータ駆動を開始することができない。 As shown in FIG. 1, the induced voltage increases when the rotational speed of the motor is high. Therefore, it is relatively easy to determine the intersection between the U phase, V phase, and W phase of the induced voltage. However, when the rotational speed of the motor is low, the induced voltage becomes small as shown in FIG. For this reason, it becomes difficult to determine the intersections between the U phase, the V phase, and the W phase due to the influence of noise appearing in the waveform of the induced voltage of each phase. As a result, an accurate phase and rotation speed of the motor cannot be obtained, and the inverter cannot start motor driving synchronized with the actual rotation speed of the motor.
　このようなノイズの影響を防止するために、ヒステリシス付きコンパレータを採用したり、チャタリング防止フィルタを採用することもできる。しかしながら、これらのハードウエアまたはソフトウエアを用いた処理は、正確な位相の検出を遅らせてしまう。 In order to prevent the influence of such noise, a comparator with hysteresis or a chattering prevention filter can be adopted. However, processing using these hardware or software delays accurate phase detection.
　本発明は、上述した従来の問題点を解決するためになされたもので、正確にモータの位相および回転速度を検出してモータの同期始動を行なうことができるモータ駆動用の電力変換装置を提供することを目的とする。 The present invention has been made to solve the above-described conventional problems, and provides a power conversion device for driving a motor capable of accurately detecting the phase and rotation speed of the motor to perform synchronous start of the motor. The purpose is to do.
　上述した目的を達成するために、本発明の一態様は、モータを駆動するための電力変換装置であって、前記モータの誘起電圧を測定する電圧測定器と、前記モータに可変周波数の電力を供給するインバータと、前記インバータの出力電力を制御するベクトル制御部と、測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、前記同期始動制御部は、前記誘起電圧が予め設定された値以下であるときは、前記決定されたモータの位相および回転速度を破棄し、前記誘起電圧が前記予め設定された値よりも大きいときは、前記決定されたモータの位相および回転速度を前記ベクトル制御部に送ることを特徴とする。 In order to achieve the above-described object, one aspect of the present invention is a power conversion device for driving a motor, which includes a voltage measuring device for measuring an induced voltage of the motor, and power having a variable frequency for the motor. An inverter to be supplied; a vector control unit that controls output power of the inverter; and a synchronous start control unit that determines a phase and a rotational speed of the motor from the measured induced voltage, and the synchronous start control unit includes: When the induced voltage is less than or equal to a preset value, discard the phase and rotational speed of the determined motor, and when the induced voltage is greater than the preset value, the determined motor Are sent to the vector control unit.
　本発明の他の態様は、モータを駆動するための電力変換装置であって、前記モータの誘起電圧を測定する電圧測定器と、前記モータに可変周波数の電力を供給するインバータと、前記インバータの出力電力を制御するベクトル制御部と、測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、前記同期始動制御部は、前記決定されたモータの回転速度を周波数に換算して推定周波数を取得し、前記誘起電圧と前記モータに固有の比例定数Ｖ／ｆとから出力周波数を算出し、前記出力周波数と前記推定周波数との差が所定の値以上であるときは、前記決定されたモータの位相および回転速度を破棄し、前記出力周波数と前記推定周波数との差が前記所定の値よりも小さいときは、前記決定されたモータの位相および回転速度を前記ベクトル制御部に送ることを特徴とする。 Another aspect of the present invention is a power conversion device for driving a motor, wherein the voltage measuring device measures an induced voltage of the motor, an inverter that supplies electric power of variable frequency to the motor, A vector control unit that controls output power; and a synchronous start control unit that determines a phase and a rotational speed of the motor from the measured induced voltage, and the synchronous start control unit includes the determined rotational speed of the motor. Is converted into a frequency to obtain an estimated frequency, an output frequency is calculated from the induced voltage and a proportional constant V / f specific to the motor, and a difference between the output frequency and the estimated frequency is equal to or greater than a predetermined value. In some cases, the phase and rotational speed of the determined motor are discarded, and when the difference between the output frequency and the estimated frequency is smaller than the predetermined value, the determined mode is determined. And wherein the sending the phase and the rotational speed of the motor to the vector control unit.
　本発明のさらに他の態様は、モータを駆動するための電力変換装置であって、前記モータの誘起電圧を測定する電圧測定器と、前記モータに可変周波数の電力を供給するインバータと、前記インバータの出力電力を制御するベクトル制御部と、測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、前記同期始動制御部は、前記決定されたモータの回転速度を周波数に換算し、得られた前記モータの周波数と前記モータに固有の比例定数Ｖ／ｆとから推定電圧を算出し、前記誘起電圧と前記推定電圧との差が所定の値以上であるときは、前記決定されたモータの位相および速度を破棄し、前記誘起電圧と前記推定電圧との差が前記所定の値よりも小さいときは、前記決定されたモータの位相および速度を前記ベクトル制御部に送ることを特徴とする。 Still another aspect of the present invention is a power conversion device for driving a motor, a voltage measuring device for measuring an induced voltage of the motor, an inverter for supplying variable frequency power to the motor, and the inverter A vector control unit that controls output power of the motor, and a synchronous start control unit that determines the phase and rotation speed of the motor from the measured induced voltage, and the synchronous start control unit includes the determined rotation of the motor. The speed is converted into a frequency, an estimated voltage is calculated from the obtained motor frequency and a proportional constant V / f specific to the motor, and the difference between the induced voltage and the estimated voltage is a predetermined value or more. When the phase and speed of the determined motor are discarded, and the difference between the induced voltage and the estimated voltage is smaller than the predetermined value, the phase and speed of the determined motor are determined. And wherein the sending rate to the vector control unit.
　本発明によれば、モータの回転速度が低いときのノイズの影響を排除することができるので、正確なモータの位相および回転速度を決定することができる。したがって、自由回転しているモータの位相および回転速度に同期した電力をモータに供給してモータを始動することができる。 According to the present invention, it is possible to eliminate the influence of noise when the rotational speed of the motor is low, so that the accurate phase and rotational speed of the motor can be determined. Therefore, the motor can be started by supplying electric power synchronized with the phase and rotational speed of the freely rotating motor.
モータの回転速度が高いときのモータの誘起電圧を示す図である。It is a figure which shows the induced voltage of a motor when the rotational speed of a motor is high. モータの回転速度が低いときのモータの誘起電圧を示す図である。It is a figure which shows the induced voltage of a motor when the rotational speed of a motor is low. 本発明の一実施形態に係る電力変換装置を示すブロック図である。It is a block diagram which shows the power converter device which concerns on one Embodiment of this invention. インバータ制御部のブロック図である。It is a block diagram of an inverter control part. 図４に示す同期始動制御部を示すブロック図である。It is a block diagram which shows the synchronous starting control part shown in FIG. Ｕ相、Ｖ相、Ｗ相の電圧信号と、Ｕ－Ｖ相の線間電圧を示すパルス信号ＰＵＶと、Ｖ－Ｗ相の線間電圧を示すパルス信号ＰＶＷを表すグラフである。5 is a graph showing a U-phase, V-phase, and W-phase voltage signal, a pulse signal P UV indicating a line voltage in the U-V phase, and a pulse signal P VW indicating a line voltage in the V-W phase. 自由回転しているモータの角周波数を算出するフローチャートを示す図である。It is a figure which shows the flowchart which calculates the angular frequency of the motor which is rotating freely. モータの同期始動の動作を示すフローチャートである。It is a flowchart which shows the operation | movement of the synchronous start of a motor. Ｕ相およびＶ相の電圧信号と、Ｕ－Ｖ相の線間電圧を示すパルス信号ＰＵＶを表すグラフである。It is a graph showing the pulse signal PUV which shows the voltage signal of U phase and V phase, and the line voltage of UV phase. モータの同期始動動作の他の実施形態を示すフローチャートである。It is a flowchart which shows other embodiment of the synchronous starting operation | movement of a motor. モータの同期始動動作のさらに他の実施形態を示すフローチャートである。It is a flowchart which shows other embodiment of the synchronous starting operation | movement of a motor.
　以下、本発明の実施形態について図面を参照して説明する。
　図３は、本発明の一実施形態に係る電力変換装置を示すブロック図である。図３に示す例では、電力変換装置５は、ポンプＰに連結されたモータＭを駆動するために使用されている。図３に示すように、電力変換装置５は、インバータ１０、センサ部１５、インバータ制御部１６、記憶部１７、および操作通信部１９を備えている。 Embodiments of the present invention will be described below with reference to the drawings.
FIG. 3 is a block diagram showing a power converter according to an embodiment of the present invention. In the example shown in FIG. 3, the power converter 5 is used to drive a motor M connected to the pump P. As shown in FIG. 3, the power conversion device 5 includes an inverter 10, a sensor unit 15, an inverter control unit 16, a storage unit 17, and an operation communication unit 19.
　インバータ１０は、コンバータ回路１１、インバータ回路１２、ゲートドライブ回路１３を有している。コンバータ回路１１は整流回路を有しており、商用電源１から供給される３相の交流電力を直流電力に変換するように構成されている。インバータ回路１２は、ＩＧＢＴ（絶縁ゲートバイポーラトランジスタ）などのスイッチング素子を有しており、コンバータ回路１１によって変換された直流電力から３相の交流電力を生成する。ゲートドライブ回路１３は、インバータ回路１２の各スイッチング素子を開閉するためのゲートドライブ信号を生成する。インバータ回路１２のスイッチング素子は、ゲートドライブ回路１３からのゲートドライブ信号に従って駆動され、これによりインバータ回路１２は可変周波数の交流電力を出力する。 The inverter 10 has a converter circuit 11, an inverter circuit 12, and a gate drive circuit 13. The converter circuit 11 has a rectifier circuit, and is configured to convert three-phase AC power supplied from the commercial power source 1 into DC power. The inverter circuit 12 includes a switching element such as an IGBT (insulated gate bipolar transistor), and generates three-phase AC power from the DC power converted by the converter circuit 11. The gate drive circuit 13 generates a gate drive signal for opening and closing each switching element of the inverter circuit 12. The switching element of the inverter circuit 12 is driven in accordance with a gate drive signal from the gate drive circuit 13, and the inverter circuit 12 thereby outputs AC power having a variable frequency.
　センサ部１５は電流測定器２０および電圧測定器２１を有している。電流測定器２０は、インバータ回路１２から出力される三相電流を測定して、その測定値（出力電流信号）をインバータ制御部１６に送る。電圧測定器２１は、モータＭが発生する誘起電圧を測定して、その測定値（誘起電圧信号）をインバータ制御部１６に送る。センサ部１５は、ポンプＰの吐出圧力、流量などの制御対象を測定する各種センサをさらに有してもよい。図３の符号２５は、ポンプＰの吐出圧力を測定する圧力センサである。 The sensor unit 15 has a current measuring device 20 and a voltage measuring device 21. The current measuring device 20 measures the three-phase current output from the inverter circuit 12 and sends the measured value (output current signal) to the inverter control unit 16. The voltage measuring device 21 measures the induced voltage generated by the motor M and sends the measured value (induced voltage signal) to the inverter control unit 16. The sensor unit 15 may further include various sensors that measure a control target such as the discharge pressure and flow rate of the pump P. Reference numeral 25 in FIG. 3 is a pressure sensor for measuring the discharge pressure of the pump P.
　記憶部１７は不揮発性のメモリであり、インバータ回路１２の駆動および制御のために必要な各種パラメータや、制御プログラムなどが格納されている。また、記憶部１７には、吐出圧力制御などのポンプ運転制御に必要なプログラムや各種パラメータが記憶されている。 The storage unit 17 is a non-volatile memory and stores various parameters necessary for driving and controlling the inverter circuit 12, a control program, and the like. The storage unit 17 stores programs and various parameters necessary for pump operation control such as discharge pressure control.
　操作通信部１９は、電力変換装置５の外部からの操作により、電力変換装置５の運転を開始および停止し、また各種設定値を設定するように構成されている。また、操作通信部１９は、外部から周波数指令信号を受信し、また運転状況を示す信号を外部に出力する。操作通信部１９は、より上位の制御装置との接続を通信を介して行うように構成されてもよい。 The operation communication unit 19 is configured to start and stop the operation of the power conversion device 5 and set various setting values by an operation from the outside of the power conversion device 5. Moreover, the operation communication part 19 receives a frequency command signal from the outside, and outputs the signal which shows a driving condition outside. The operation communication unit 19 may be configured to connect to a higher-level control device via communication.
　インバータ制御部１６は、センサ部１５から送られる測定信号、および操作通信部１９から送られる周波数指令信号に基づいて、モータＭの回転速度を制御する。すなわち、インバータ制御部１６は、周波数指令信号を操作通信部１９から受け、センサ部１５からの測定信号に基づいてＰＷＭ信号を生成する。このＰＷＭ信号はゲートドライブ回路１３に送られる。ゲートドライブ回路１３は、ＰＷＭ信号に基づいて、インバータ回路１２のスイッチング素子を駆動するためのゲートドライブ信号を生成する。インバータ回路１２のスイッチング素子は、ゲートドライブ回路１３からのゲートドライブ信号に従って駆動され、これによりインバータ回路１２は可変周波数の交流電力を出力する。 The inverter control unit 16 controls the rotation speed of the motor M based on the measurement signal sent from the sensor unit 15 and the frequency command signal sent from the operation communication unit 19. That is, the inverter control unit 16 receives the frequency command signal from the operation communication unit 19 and generates a PWM signal based on the measurement signal from the sensor unit 15. This PWM signal is sent to the gate drive circuit 13. The gate drive circuit 13 generates a gate drive signal for driving the switching element of the inverter circuit 12 based on the PWM signal. The switching element of the inverter circuit 12 is driven in accordance with a gate drive signal from the gate drive circuit 13, and the inverter circuit 12 thereby outputs AC power having a variable frequency.
　図４はインバータ制御部１６のブロック図である。インバータ制御部１６は、モータＭに供給する電流をトルク電流成分と磁化電流成分とに分解してこれらを独立に制御するベクトル制御部３０と、モータＭに発生する誘起電圧からモータＭの位相および回転速度を決定する同期始動制御部５０とを有している。同期始動制御部５０は、自由回転しているモータＭの回転速度を決定することができるので、ベクトル制御部３０はモータＭの回転速度に同期したインバータ駆動を開始することができる。 FIG. 4 is a block diagram of the inverter control unit 16. The inverter control unit 16 decomposes the current supplied to the motor M into a torque current component and a magnetizing current component and independently controls them, and a phase of the motor M from an induced voltage generated in the motor M. And a synchronous start control unit 50 for determining the rotation speed. Since the synchronous start control unit 50 can determine the rotation speed of the freely rotating motor M, the vector control unit 30 can start the inverter drive synchronized with the rotation speed of the motor M.
　インバータ１０の３相の出力電流は、電流測定器２０により測定される。測定された三相電流Ｉｕ，Ｉｖ，Ｉｗは、３／２相変換部３２、静止／回転座標変換部３３により、回転座標系上の二相電流Ｉｄ，Ｉｑに変換された後、磁化電圧制御部３４およびトルク電圧制御部３５に入力される。磁化電圧制御部３４は、磁化電流Ｉｄと磁化電流指令値Ｉｄ*との偏差を０とする磁化電圧指令値Ｖｄ*をＰＩ演算により求める。磁化電流指令値Ｉｄ*は、モータモデルを用いて算出された理想的な磁化電流である。トルク電圧制御部３５は、トルク電流Ｉｑとトルク電流指令値Ｉｑ*との偏差を０とするトルク電圧指令値Ｖｑ*をＰＩ演算により求める。 The three-phase output current of the inverter 10 is measured by the current measuring device 20. The measured three-phase currents Iu, Iv, and Iw are converted into two-phase currents Id and Iq on the rotating coordinate system by the 3 / 2-phase converting unit 32 and the stationary / rotating coordinate converting unit 33, and then the magnetization voltage control is performed. Is input to the unit 34 and the torque voltage control unit 35. The magnetizing voltage control unit 34 obtains a magnetizing voltage command value Vd * in which the deviation between the magnetizing current Id and the magnetizing current command value Id * is 0 by PI calculation. The magnetizing current command value Id * is an ideal magnetizing current calculated using a motor model. The torque voltage control unit 35 obtains a torque voltage command value Vq * in which a deviation between the torque current Iq and the torque current command value Iq * is 0 by PI calculation.
　目標トルク電流決定部３７は、外部から入力された角速度指令値ω*と現在の角速度ωとの偏差が０となるようにＰＩ演算を行なってトルク電流指令値Ｉｑ*を決定する。現在の角速度ωは、電圧指令値Ｖｄ*，Ｖｑ*に基づき、軸誤差推定器（ＰＬＬ）３８によって求められる。さらに、積分器３９により角速度ωから位相θが求められる。得られた位相θは、静止／回転座標変換部３３および回転／静止座標変換部４０に送られる。電圧指令値Ｖｄ*，Ｖｑ*は、回転／静止座標変換部４０および２／３相変換部４１を経て固定座標系上の３相電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*に変換される。 The target torque current determination unit 37 performs the PI calculation so that the difference between the angular velocity command value ω * input from the outside and the current angular velocity ω becomes zero, and determines the torque current command value Iq *. The current angular velocity ω is obtained by an axis error estimator (PLL) 38 based on the voltage command values Vd * and Vq *. Further, the phase θ is obtained from the angular velocity ω by the integrator 39. The obtained phase θ is sent to the stationary / rotational coordinate converter 33 and the rotational / static coordinate converter 40. The voltage command values Vd * and Vq * are converted into the three-phase voltage command values Vu *, Vv * and Vw * on the fixed coordinate system via the rotation / stationary coordinate conversion unit 40 and the 2/3 phase conversion unit 41.
　ベクトル制御部３０は、これら三相電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*に対応したＰＷＭ信号を生成し、このＰＷＭ信号をゲートドライブ回路１３に送る。ゲートドライブ回路１３は、三相電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*に対応するＰＷＭ信号に基づいてゲートドライブ回路ＰＷＭ信号を生成し、スイッチング素子は、ゲートドライブ回路ＰＷＭ信号に基づいて動作（オン、オフ）される。このように、インバータ１０はベクトル制御部３０からの三相電圧指令値に基づいた電圧を生成し、これをモータＭに印加する。 The vector control unit 30 generates a PWM signal corresponding to these three-phase voltage command values Vu *, Vv *, Vw *, and sends this PWM signal to the gate drive circuit 13. The gate drive circuit 13 generates a gate drive circuit PWM signal based on the PWM signal corresponding to the three-phase voltage command values Vu *, Vv *, Vw *, and the switching element operates based on the gate drive circuit PWM signal ( On, off). Thus, the inverter 10 generates a voltage based on the three-phase voltage command value from the vector control unit 30 and applies it to the motor M.
　ポンプが水道本管に直結された、いわゆる直結型の給水装置では、ポンプが停止しているときでも、水道本管からの液体の圧力により給水が行われることがある。したがって、インバータ１０によりモータＭが駆動されていないときであっても、ポンプ内を流れる液体によりポンプの羽根車およびこれに連結されたモータＭが回転する。このようにモータＭが自由回転している状態からインバータ１０によりモータＭを始動するためには、回転しているモータＭの誘起電圧の周波数および位相に同期した電圧をインバータ１０が生成する必要がある。 In a so-called directly connected water supply device in which the pump is directly connected to the water main, water supply may be performed by the pressure of the liquid from the water main even when the pump is stopped. Accordingly, even when the motor M is not driven by the inverter 10, the pump impeller and the motor M connected thereto are rotated by the liquid flowing in the pump. Thus, in order to start the motor M by the inverter 10 from the state where the motor M is freely rotating, it is necessary for the inverter 10 to generate a voltage synchronized with the frequency and phase of the induced voltage of the rotating motor M. is there.
　モータＭの自由回転は、瞬間的な停電の直後にも起こる。すなわち、モータＭがインバータ１０により駆動されている最中に瞬間的な停電が起こると、モータＭに電力が供給されていなくても、モータＭのロータは慣性によりしばらくの間は回転し続ける。停電が復旧した後に自由回転しているモータＭを始動するときは、モータＭの誘起電圧の周波数および位相に同期した電圧をインバータ１０が生成する必要がある。 The free rotation of the motor M also occurs immediately after an instantaneous power failure. That is, if a momentary power failure occurs while the motor M is being driven by the inverter 10, even if no power is supplied to the motor M, the rotor of the motor M continues to rotate for a while due to inertia. When starting the freely rotating motor M after the power failure is restored, the inverter 10 needs to generate a voltage synchronized with the frequency and phase of the induced voltage of the motor M.
　本明細書では、モータが電力の供給を受けずに、外部の運動エネルギーまたは慣性により回転している状態を「自由回転」という。このような自由回転しているモータとインバータとの同期始動を実現するために、本電力変換装置５は、モータＭのＵ相、Ｖ相、Ｗ相の誘起電圧を測定し、その測定された電圧から自由回転しているモータの位相（磁極位置）および回転速度を推定し、その推定された位相および回転速度に基づいて、インバータ１０の制御を開始する。 In this specification, a state in which the motor is rotated by external kinetic energy or inertia without being supplied with electric power is referred to as “free rotation”. In order to realize the synchronous start of the freely rotating motor and the inverter, the power converter 5 measures the induced voltages of the U phase, V phase, and W phase of the motor M, and the measurement is performed. The phase (magnetic pole position) and rotation speed of the motor that is freely rotating are estimated from the voltage, and control of the inverter 10 is started based on the estimated phase and rotation speed.
　回転しているモータＭは、誘起電圧を発生する。電力変換装置５はこのモータＭの誘起電圧からモータＭの位相および回転速度を決定する。図５は、図４に示す同期始動制御部５０を示すブロック図である。図５に示すように、同期始動制御部５０は、Ｕ相－Ｖ相間の電圧差からパルス信号を生成する第１の線間電圧比較器５１Ａ、Ｖ相－Ｗ相間の電圧差からパルス信号を生成する第２の線間電圧比較器５１Ｂ、第１の線間電圧比較器５１Ａにより生成されたパルス信号のパルスエッジを検出する第１のパルスエッジ検出部５２Ａ、第２の線間電圧比較器５１Ｂにより生成されたパルス信号のパルスエッジを検出する第２のパルスエッジ検出部５２Ｂ、およびパルスエッジからモータの位相を特定し、かつモータの回転速度を算出する速度算出部５５を有している。 Rotating motor M generates an induced voltage. The power converter 5 determines the phase and rotational speed of the motor M from the induced voltage of the motor M. FIG. 5 is a block diagram showing the synchronous start control unit 50 shown in FIG. As shown in FIG. 5, the synchronous start control unit 50 includes a first line voltage comparator 51A that generates a pulse signal from the voltage difference between the U phase and the V phase, and a pulse signal from the voltage difference between the V phase and the W phase. The second line voltage comparator 51B to be generated, the first pulse edge detector 52A for detecting the pulse edge of the pulse signal generated by the first line voltage comparator 51A, and the second line voltage comparator The second pulse edge detector 52B that detects the pulse edge of the pulse signal generated by 51B, and the speed calculator 55 that specifies the phase of the motor from the pulse edge and calculates the rotational speed of the motor. .
　電圧測定器２１は、インバータ１０とモータＭとを接続する三相の線の電圧を測定し、Ｕ相、Ｖ相、Ｗ相の電圧信号を出力する。この三相の出力電圧信号は、自由回転しているモータＭの誘起電圧を示す信号である。出力電圧信号はゲイン調整器４９により増幅された後、第１の線間電圧比較器５１Ａ、第２の線間電圧比較器５１Ｂ、および速度算出部５５のＡＤコンバータ５５ａに送られる。 The voltage measuring device 21 measures the voltage of the three-phase line connecting the inverter 10 and the motor M, and outputs U-phase, V-phase, and W-phase voltage signals. This three-phase output voltage signal is a signal indicating the induced voltage of the freely rotating motor M. The output voltage signal is amplified by the gain adjuster 49 and then sent to the first line voltage comparator 51A, the second line voltage comparator 51B, and the AD converter 55a of the speed calculation unit 55.
　第１の線間電圧比較器５１Ａは、Ｕ相の電圧信号とＶ相の電圧信号とを比較して、パルス信号ＰＵＶを生成する。具体的には、Ｖ相の電圧信号がＵ相の電圧信号よりも高いときは高位信号を発生し、Ｖ相の電圧信号がＵ相の電圧信号よりも低いときは低位信号を発生する。同様に、第２の線間電圧比較器５１Ｂは、Ｖ相の電圧信号とＷ相の電圧信号とを比較して、パルス信号ＰＶＷを生成する。すなわち、Ｗ相の電圧信号がＶ相の電圧信号よりも高いときは高位信号を発生し、Ｗ相の電圧信号がＶ相の電圧信号よりも低いときは低位信号を発生する。 The first line voltage comparator 51A compares the U-phase voltage signal with the V-phase voltage signal to generate a pulse signal PUV . Specifically, a high-level signal is generated when the V-phase voltage signal is higher than the U-phase voltage signal, and a low-level signal is generated when the V-phase voltage signal is lower than the U-phase voltage signal. Similarly, the second line voltage comparator 51B compares the V-phase voltage signal and the W-phase voltage signal to generate a pulse signal PVW . That is, a high level signal is generated when the W phase voltage signal is higher than the V phase voltage signal, and a low level signal is generated when the W phase voltage signal is lower than the V phase voltage signal.
　図６は、Ｕ相、Ｖ相、Ｗ相の電圧信号と、Ｕ－Ｖ相の線間電圧を示すパルス信号ＰＵＶと、Ｖ－Ｗ相の線間電圧を示すパルス信号ＰＶＷを表すグラフである。グラフから分かるように、パルス信号ＰＵＶの立ち上がりエッジＥ１および立ち下がりエッジＥ２は、Ｕ相の電圧信号とＶ相の電圧信号とが交差する点で現れ、パルス信号ＰＶＷの立ち上がりエッジＥ３および立ち下がりエッジＥ４は、Ｖ相の電圧信号とＷ相の電圧信号とが交差する点で現れる。 FIG. 6 is a graph showing U-phase, V-phase, and W-phase voltage signals, a pulse signal P UV indicating the line voltage of the U-V phase, and a pulse signal P VW indicating the line voltage of the V-W phase. It is. As can be seen from the graph, the pulse signal P UV rising edge E1 and the falling edge E2 is manifested in that the voltage signal of the voltage signal and the V-phase of the U-phase crossing, rising edge E3 and falling of the pulse signal P VW The falling edge E4 appears at the point where the V-phase voltage signal and the W-phase voltage signal intersect.
　線間電圧比較器５１Ａ，５１Ｂで生成されたパルス信号ＰＵＶおよびパルス信号ＰＶＷは、それぞれ第１のパルスエッジ検出部５２Ａおよび第２のパルスエッジ検出部５２Ｂに送られる。第１のパルスエッジ検出部５２Ａは、パルス信号ＰＵＶの立ち上がりエッジＥ１および立ち下がりエッジＥ２を検出し、これら立ち上がりエッジＥ１および立ち下がりエッジＥ２が検出されるたびに、パルスエッジ検出信号を速度算出部５５に送る。同様に、第２のパルスエッジ検出部５２Ｂは、パルス信号ＰＶＷの立ち上がりエッジＥ３および立ち下がりエッジＥ４を検出し、これら立ち上がりエッジＥ３および立ち下がりエッジＥ４が検出されるたびに、パルスエッジ検出信号を速度算出部５５に送る。以下、これらパルス信号ＰＵＶおよびパルス信号ＰＶＷの立ち上がりエッジおよび立ち下がりエッジを、総称してパルスエッジと呼ぶ。図６から、モータの誘起電圧の１周期内には、４つのパルスエッジＥ１，Ｅ２，Ｅ３，Ｅ４が現れることが分かる。 The pulse signal P UV and the pulse signal P VW generated by the line voltage comparators 51A and 51B are sent to the first pulse edge detector 52A and the second pulse edge detector 52B, respectively. First pulse edge detection unit 52A, each time detects the pulse signal P UV rising edge E1 and the falling edge E2, these rising edges E1 and falling edge E2 is detected, the speed calculated pulse edge detection signal Send to part 55. Similarly, the second pulse edge detector 52B detects the rising edge E3 and the falling edge E4 of the pulse signal PVW , and each time the rising edge E3 and the falling edge E4 are detected, the pulse edge detection signal Is sent to the speed calculation unit 55. Hereinafter, the rising edge and falling edge of the pulse signal P UV and the pulse signal P VW are collectively referred to as a pulse edge. FIG. 6 shows that four pulse edges E1, E2, E3, and E4 appear within one cycle of the induced voltage of the motor.
　速度算出部５５は、第１のパルスエッジ検出部５２Ａまたは第２のパルスエッジ検出部５２Ｂからのパルスエッジ検出信号を受けると、以下に説明するように、モータＭの位相の特定および角周波数（すなわち回転速度のスカラー量）の計算を開始する。 When receiving the pulse edge detection signal from the first pulse edge detection unit 52A or the second pulse edge detection unit 52B, the speed calculation unit 55 specifies the phase of the motor M and the angular frequency ( That is, the calculation of the rotational speed scalar quantity) is started.
　図７は、自由回転しているモータの角周波数（回転速度）を算出するフローチャートを示す図である。速度算出部５５は、パルスエッジ検出信号を受けると、現在の時刻ｔｎを取得する。次に、速度算出部５５は、検出されたパルスエッジの位相（角度）θｎを特定し、時刻ｔｎにおけるモータの位相θｎをベクトル制御部３０の積分器３９に送る。位相θｎは、誘起電圧の１周期内に現れるパルスエッジごとに予め設定されている。すなわち、パルスエッジＥ１の位相は５／６π、パルスエッジＥ２の位相は－１／６π、パルスエッジＥ３の位相は－１／２π、パルスエッジＥ４の位相は１／２πに設定されている。 FIG. 7 is a diagram illustrating a flowchart for calculating an angular frequency (rotational speed) of a motor that is freely rotating. When receiving the pulse edge detection signal, the speed calculation unit 55 acquires the current time t n . Next, the speed calculation unit 55 identifies the phase (angle) θ n of the detected pulse edge, and sends the phase θ n of the motor at time t n to the integrator 39 of the vector control unit 30. The phase θ n is set in advance for each pulse edge that appears within one cycle of the induced voltage. That is, the phase of the pulse edge E1 is set to 5 / 6π, the phase of the pulse edge E2 is set to −1 / 6π, the phase of the pulse edge E3 is set to −1 / 2π, and the phase of the pulse edge E4 is set to 1 / 2π.
　したがって、検出されたパルスエッジがパルスエッジＥ１であれば、速度算出部５５はモータの位相θｎとして５／６πを積分器３９に送る。同様に、検出されたパルスエッジがパルスエッジＥ２であれば、速度算出部５５はモータの位相θｎとして－１／６πを積分器３９に送る。検出されたパルスエッジがパルスエッジＥ３であれば、速度算出部５５はモータの位相θｎとして－１／２πを積分器３９に送る。検出されたパルスエッジがパルスエッジＥ４であれば、速度算出部５５はモータの位相θｎとして１／２πを積分器３９に送る。位相θｎが入力されると、積分器３９は位相θを位相θｎにリセットし（位相θを位相θｎに置き換え）、位相θｎを静止／回転座標変換部３３および回転／静止座標変換部４０に送る。 Therefore, if the detected pulse edge is the pulse edge E1, the speed calculation unit 55 sends 5 / 6π to the integrator 39 as the phase θ n of the motor. Similarly, if the detected pulse edge is the pulse edge E2, the speed calculation unit 55 sends −1 / 6π to the integrator 39 as the phase θ n of the motor. If the detected pulse edge is the pulse edge E3, the speed calculation unit 55 sends -1 / 2π to the integrator 39 as the phase θ n of the motor. If the detected pulse edge at the pulse edge E4, the speed calculation portion 55 sends the 1/2 [pi as the phase theta n of the motor to the integrator 39. When the phase theta n is input, the integrator 39 resets the phase theta phase theta n (replacing the phase theta phase theta n), the phase theta n stationary / rotating coordinate conversion section 33 and a rotating / stationary coordinate converter Send to part 40.
　図６に示すように、速度算出部５５は、前回パルスエッジを検出してからの経過時間Δｔと、現在の位相θｎと、前回パルスエッジが検出されたときの位相θｎ－１とから、自由回転しているモータの角周波数ωｎを次のように決定する。
Figure JPOXMLDOC01-appb-M000001
 　このようにして、自由回転しているモータの位相θｎおよび角周波数ωｎが決定される。 As shown in FIG. 6, the speed calculation unit 55 uses the elapsed time Δt since the previous pulse edge was detected, the current phase θ n, and the phase θ n−1 when the previous pulse edge was detected. The angular frequency ω n of the freely rotating motor is determined as follows.
Figure JPOXMLDOC01-appb-M000001
 In this way, the phase θ n and the angular frequency ω n of the freely rotating motor are determined.
　図６に示す３相電圧は、比較的大きな振幅を有する。しかしながら、自由回転しているモータの回転速度が低いときは、図２に示すように、誘起電圧は小さくなる。このため、各相の電圧の波形に現れるノイズの影響で、Ｕ相、Ｖ相、Ｗ相間の交差点から決定されるパルス信号が不安定となる。結果として、モータの正確な位相や回転速度を得ることができない。 The three-phase voltage shown in FIG. 6 has a relatively large amplitude. However, when the rotational speed of the freely rotating motor is low, the induced voltage becomes small as shown in FIG. For this reason, the pulse signal determined from the intersection between the U phase, the V phase, and the W phase becomes unstable due to the influence of noise appearing in the voltage waveform of each phase. As a result, an accurate phase and rotation speed of the motor cannot be obtained.
　そこで、速度算出部５５は、モータの誘起電圧が小さいときにはモータを同期運転させない機能を有している。図８は、モータの同期始動の動作を示すフローチャートである。インバータ１０の停止中にパルスエッジが検出されると（ステップ１）、タイマーが０にリセットされ、タイマーが始動される（ステップ２）。モータの出力電圧（誘起電圧）の測定値は、電圧測定器２１からＡＤコンバータ５５ａを介して速度算出部５５に取り込まれ、予め設定されたしきい値と比較される（ステップ３）。モータの出力電圧がしきい値以下であるときは、角周波数ωｎおよび位相θｎは破棄され、角周波数ωｎおよび位相θｎはいずれも０に設定される（ステップ５）。そして、０に設定された角周波数ωｎおよび位相θｎがベクトル制御部３０に送られる（ステップ６）。 Therefore, the speed calculation unit 55 has a function of not causing the motor to operate synchronously when the induced voltage of the motor is small. FIG. 8 is a flowchart showing the synchronous start operation of the motor. If a pulse edge is detected while the inverter 10 is stopped (step 1), the timer is reset to 0 and the timer is started (step 2). The measured value of the motor output voltage (induced voltage) is taken from the voltage measuring device 21 to the speed calculation unit 55 via the AD converter 55a and compared with a preset threshold value (step 3). When the motor output voltage is equal to or lower than the threshold value, the angular frequency ω n and the phase θ n are discarded, and the angular frequency ω n and the phase θ n are both set to 0 (step 5). Then, the angular frequency ω n and the phase θ n set to 0 are sent to the vector control unit 30 (step 6).
　一方、モータの出力電圧がしきい値よりも大きいときは、上記式（１）を用いて角周波数ωｎが算出され、さらに、検出されたパルスエッジに基づいて位相θｎが特定される（ステップ４）。その後、得られた角周波数ωｎおよび位相θｎがベクトル制御部３０に送られる（ステップ６）。ベクトル制御部３０は、外部から運転指令が入力したか否かを判断し（ステップ７）、運転指令が未入力の場合には、処理フローはステップ１に戻る。一方、運転指令が入力された場合には、自由回転しているモータの速度に同期してモータを始動させる（ステップ８）。なお、本実施形態では、ステップ３でモータの出力電圧がしきい値より大きいかどうかを判断した後にステップ４で角周波数ωｎおよび位相θｎが算出されるが、ステップ３とステップ４の順番を入れ替えて、先に角周波数ωｎおよび位相θｎを算出してから、モータの出力電圧がしきい値より大きいかどうかを判断してもよい。 On the other hand, when the output voltage of the motor is larger than the threshold value, the angular frequency ω n is calculated using the above equation (1), and the phase θ n is specified based on the detected pulse edge ( Step 4). Thereafter, the obtained angular frequency ω n and phase θ n are sent to the vector control unit 30 (step 6). The vector control unit 30 determines whether or not an operation command is input from the outside (step 7), and when the operation command is not input, the process flow returns to step 1. On the other hand, when the operation command is input, the motor is started in synchronization with the speed of the freely rotating motor (step 8). In this embodiment, the angular frequency ω n and the phase θ n are calculated in step 4 after determining whether the output voltage of the motor is larger than the threshold value in step 3, but the order of step 3 and step 4 is calculated. May be replaced, and the angular frequency ω n and the phase θ n may be calculated first, and then it may be determined whether or not the motor output voltage is greater than the threshold value.
　図４に示すスイッチＳＷ１は、軸誤差推定器３８および同期始動制御部５０に接続されており、軸誤差推定器３８からの角周波数ωＣおよび同期始動制御部５０からの角周波数ωｎのうちのいずれか一方のみを選択的に通過させるように構成されている。したがって、目標トルク電流決定部３７および積分器３９に入力される角周波数ωとしては、角周波数ωＣまたは角周波数ωｎのいずれかが採用される。ステップ７で運転指令が入力されたと判断されるまでは、スイッチＳＷ１を介して同期始動制御部５０とベクトル制御部３０とが接続され、同期始動制御部５０からの角周波数ωｎがベクトル制御部３０に入力され続ける。そして、運転指令が入力されたと判断されると、軸誤差推定器３８からの角周波数ωＣがスイッチＳＷ１を介して目標トルク電流決定部３７および積分器３９に送られ、ベクトル制御が行われる。 The switch SW1 shown in FIG. 4 is connected to the axis error estimator 38 and the synchronous start control unit 50. Of the angular frequency ω C from the axis error estimator 38 and the angular frequency ω n from the synchronous start control unit 50, Only one of them is selectively passed. Therefore, as the angular frequency ω input to the target torque current determining unit 37 and the integrator 39, either the angular frequency ω C or the angular frequency ω n is employed. Until it is determined in step 7 that the operation command is input, the synchronous start control unit 50 and the vector control unit 30 are connected via the switch SW1, and the angular frequency ω n from the synchronous start control unit 50 is determined as the vector control unit. 30 continues to be input. When the operation command is judged to have been input, the angular frequency omega C from the axis error estimator 38 is sent to the target torque current determination unit 37 and the integrator 39 via the switch SW1, the vector control is performed.
　モータが回転していない場合は、パルスエッジは検出されない。したがって、ステップ１において、所定時間内にパルスエッジが検出されなかった場合には、タイマーがリセットされ（ステップ９）、さらに角周波数ωｎおよび位相θｎはいずれも０に設定される（ステップ５）。 If the motor is not rotating, no pulse edge is detected. Therefore, if the pulse edge is not detected within the predetermined time in step 1, the timer is reset (step 9), and the angular frequency ω n and the phase θ n are both set to 0 (step 5). ).
　上述したように、モータの出力電圧がしきい値以下のときは、得られた角周波数ωｎおよび位相θｎは破棄され、角周波数ωｎおよび位相θｎは０に設定される（ステップ５参照）。これは、モータの誘起電圧が小さいことに起因して、モータの出力電圧波形に現れたノイズがパルスエッジを生成したと考えられるからである。つまり、ノイズに起因して生成されたパルスエッジからは、実際のモータの回転速度および位相を決定することができない。一方、モータの出力電圧がしきい値よりも大きいときは、算出された角周波数ωｎおよび特定された位相θｎがベクトル制御部３０に送られる（ステップ４参照）。 As described above, when the motor output voltage is equal to or lower than the threshold value, the obtained angular frequency ω n and phase θ n are discarded, and the angular frequency ω n and phase θ n are set to 0 (step 5). reference). This is because the noise appearing in the motor output voltage waveform is considered to have generated a pulse edge due to the small induced voltage of the motor. That is, the actual rotational speed and phase of the motor cannot be determined from the pulse edge generated due to noise. On the other hand, when the output voltage of the motor is larger than the threshold value, the calculated angular frequency ω n and the specified phase θ n are sent to the vector control unit 30 (see step 4).
　角周波数ωｎは、スイッチＳＷ１を介して目標トルク電流決定部３７および積分器３９に入力され、位相θｎは積分器３９を介して回転／静止座標変換部４０および静止／回転座標変換部３３に入力される。そして、ベクトル制御部３０は、自由回転しているモータＭの位相および回転速度に同期した電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*を生成する。インバータ１０は、電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*に従って電力を出力し、モータＭを始動させる（ステップ８）。このようにして、電力変換装置５は、インバータ１０の出力電圧の周波数および位相を、自由回転しているモータの出力電圧の周波数および位相に同期させた状態で、モータを始動させることができる。 The angular frequency ω n is input to the target torque current determination unit 37 and the integrator 39 via the switch SW1, and the phase θ n is input to the rotation / stationary coordinate conversion unit 40 and the stationary / rotation coordinate conversion unit 33 via the integrator 39. Is input. Then, the vector control unit 30 generates voltage command values Vu *, Vv *, Vw * synchronized with the phase and rotation speed of the freely rotating motor M. The inverter 10 outputs electric power according to the voltage command values Vu *, Vv *, Vw *, and starts the motor M (step 8). In this manner, the power conversion device 5 can start the motor in a state where the frequency and phase of the output voltage of the inverter 10 are synchronized with the frequency and phase of the output voltage of the freely rotating motor.
　モータの回転速度が遅くなるほど、モータの誘起電圧は低くなる。このため、始動しようとするモータの回転速度が０または非常に低い場合は、モータの出力電圧が上記しきい値を上回ることができない。結果として、処理フローはステップ４に進むことができず、モータの同期始動ができない。そこで、上述したように、タイマーにより計測された時間が予め設定した時間を過ぎたときは、角周波数ωｎが０であると仮定してモータが始動される（図８のステップ９，５参照）。具体的には、パルスエッジが所定時間内に検出されなかった場合は、角周波数ωｎが０に設定される。このような処理ステップを処理フローに組み入れることにより、モータの回転速度が０または非常に低いときであってもモータが始動される。 The slower the motor rotation speed, the lower the induced voltage of the motor. For this reason, when the rotational speed of the motor to be started is 0 or very low, the output voltage of the motor cannot exceed the threshold value. As a result, the process flow cannot proceed to step 4 and the motor cannot be started synchronously. Therefore, as described above, when the time measured by the timer exceeds a preset time, the motor is started assuming that the angular frequency ω n is 0 (see steps 9 and 5 in FIG. 8). ). Specifically, if the pulse edge is not detected within a predetermined time, the angular frequency ω n is set to zero. By incorporating such processing steps into the processing flow, the motor is started even when the rotational speed of the motor is zero or very low.
　本実施形態では、２つのパルス信号ＰＵＶおよびパルス信号ＰＶＷが生成されるので、誘起電圧の１周期内には、４つのパルスエッジＥ１，Ｅ２，Ｅ３，Ｅ４が現れる。このパルスエッジが現れる順序から、モータの回転方向を決定することができる。具体的には、モータが正方向に回転しているときは、Ｅ１，Ｅ３，Ｅ２，Ｅ４の順にパルスエッジが現れる。一方、具体的には、モータが逆方向に回転しているときは、Ｅ４，Ｅ２，Ｅ３，Ｅ１の順にパルスエッジが現れる。したがって、速度算出部５５は、パルスエッジの順序からモータの回転方向を決定することができる。 In the present embodiment, since two pulse signals P UV and P VW are generated, four pulse edges E1, E2, E3, E4 appear within one cycle of the induced voltage. The rotation direction of the motor can be determined from the order in which the pulse edges appear. Specifically, when the motor is rotating in the forward direction, pulse edges appear in the order of E1, E3, E2, and E4. On the other hand, specifically, when the motor rotates in the reverse direction, pulse edges appear in the order of E4, E2, E3, and E1. Therefore, the speed calculation unit 55 can determine the rotation direction of the motor from the order of the pulse edges.
　１つのパルス信号からはモータの回転方向を決定することはできないが、モータの位相θｎおよび角周波数ωｎを決定することはできる。図９は、Ｕ相およびＶ相の電圧信号と、Ｕ－Ｖ相の線間電圧を示すパルス信号ＰＵＶを表すグラフである。図９から分かるように、モータの出力電圧の１周期内に２つのパルスエッジＥ１，Ｅ２が現れる。したがって、パルスエッジＥ１，Ｅ２から位相θｎを特定し、さらに上記式（１）を用いて角周波数ωｎを算出することができる。 Although the rotation direction of the motor cannot be determined from one pulse signal, the phase θ n and the angular frequency ω n of the motor can be determined. FIG. 9 is a graph showing the U-phase and V-phase voltage signals and the pulse signal P UV indicating the line voltage of the U-V phase. As can be seen from FIG. 9, two pulse edges E1 and E2 appear within one cycle of the output voltage of the motor. Therefore, the phase θ n can be specified from the pulse edges E1 and E2, and the angular frequency ω n can be calculated using the above equation (1).
　図１０は、モータの同期始動動作の他の実施形態を示すフローチャートである。この実施形態では、ステップ３にて、上記式（１）を用いて角周波数ωｎが算出され、さらに、検出されたパルスエッジに基づいて位相θｎが特定される。さらに、ステップ４にて、角周波数ωｎから求められる周波数ｆｎ（以下、推定周波数ｆｎという）と、モータの出力電圧（誘起電圧）の周波数ｆi（以下、出力周波数ｆiという）との差に基づいて、算出された角周波数ωｎおよび位相θｎを破棄して、これらを０に設定するか否かが速度算出部５５により判断される。ステップ３，４以外のステップは、図８に示すステップと同じである。 FIG. 10 is a flowchart showing another embodiment of the synchronous start operation of the motor. In this embodiment, in step 3, the angular frequency ω n is calculated using the above equation (1), and the phase θ n is specified based on the detected pulse edge. Further, in step 4, the angular frequency ω frequency is determined from n f n (hereinafter, referred to as estimated frequency f n) and the frequency f i of the motor output voltage (induced voltage) (hereinafter, referred to as the output frequency f i) and Based on the difference between them, the calculated angular frequency ω n and phase θ n are discarded, and the speed calculation unit 55 determines whether or not to set them to 0. Steps other than steps 3 and 4 are the same as the steps shown in FIG.
　推定周波数ｆｎは、算出された角周波数ωｎと、公知の式ω＝２πｆとから算出することができる。一方、出力周波数ｆiは、ＡＤコンバータ５５ａに入力されたモータの出力電圧の測定値と、既知の比例定数Ｖ／ｆとから求めることができる。具体的には、モータの出力電圧の測定値を比例定数Ｖ／ｆで割ることにより、出力周波数ｆiを求めることができる。この比例定数Ｖ／ｆは、モータに固有の定数であり、モータの定格電圧をモータの定格周波数で割ることにより求められる。 The estimated frequency f n can be calculated from the calculated angular frequency ω n and the known formula ω = 2πf. On the other hand, the output frequency f i can be obtained from the measured value of the output voltage of the motor input to the AD converter 55a and the known proportionality constant V / f. Specifically, the output frequency f i can be obtained by dividing the measured value of the output voltage of the motor by the proportionality constant V / f. This proportional constant V / f is a constant inherent to the motor, and is obtained by dividing the rated voltage of the motor by the rated frequency of the motor.
　次に、推定周波数ｆｎと出力周波数ｆiとの差の絶対値（大きさ）が所定の値と比較される（ステップ４）。推定周波数ｆｎと出力周波数ｆiとの差の絶対値が所定の値以上である場合には、算出された角周波数ωｎおよび位相θｎは破棄され、角周波数ωｎおよび位相θｎは０に設定される（ステップ５）。そして、０に設定された角周波数ωｎおよび位相θｎがベクトル制御部３０に送られる（ステップ６）。 Next, the absolute value (magnitude) of the difference between the estimated frequency f n and the output frequency f i is compared with a predetermined value (step 4). If the absolute value of the difference between the estimated frequency f n and the output frequency f i is greater than or equal to a predetermined value, the calculated angular frequency ω n and phase θ n are discarded, and the angular frequency ω n and phase θ n are It is set to 0 (step 5). Then, the angular frequency ω n and the phase θ n set to 0 are sent to the vector control unit 30 (step 6).
　一方、推定周波数ｆｎと出力周波数ｆiとの差の絶対値が所定の値よりも小さい場合には、算出された角周波数ωｎおよび特定された位相θｎがベクトル制御部３０に送られる（ステップ６）。ベクトル制御部３０は、角周波数ωｎおよび位相θｎに基づいてインバータ１０への電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*を生成する。インバータ１０は、自由回転しているモータの誘起電圧の位相および周波数に同期した電圧をモータに出力する。 On the other hand, when the absolute value of the difference between the estimated frequency f n and the output frequency f i is smaller than a predetermined value, the calculated angular frequency ω n and the specified phase θ n are sent to the vector control unit 30. (Step 6). The vector control unit 30 generates voltage command values Vu *, Vv *, Vw * to the inverter 10 based on the angular frequency ω n and the phase θ n . The inverter 10 outputs a voltage synchronized with the phase and frequency of the induced voltage of the freely rotating motor to the motor.
　図１１は、モータの同期始動動作のさらに他の実施形態を示すフローチャートである。この実施形態では、ステップ３にて、上記式（１）を用いて角周波数ωｎが算出され、さらに、検出されたパルスエッジに基づいて位相θｎが特定される。さらに、ステップ４にて、角周波数ωｎから求められる推定電圧Ｖｎと、ＡＤコンバータ５５ａに入力されたモータの出力電圧Ｖｉとの差に基づいて、算出された角周波数ωｎおよび位相θｎを破棄して、これらを０に設定するか否かが速度算出部５５により判断される。ステップ３，４以外のステップは、図８に示すステップと同じである。 FIG. 11 is a flowchart showing still another embodiment of the synchronous start operation of the motor. In this embodiment, in step 3, the angular frequency ω n is calculated using the above equation (1), and the phase θ n is specified based on the detected pulse edge. Further, in step 4, the estimated voltage V n obtained from the angular frequency omega n, based on the difference between the output voltage V i of the motor that is input to the AD converter 55a, the angular frequency is calculated omega n and phase θ The speed calculator 55 determines whether to discard n and set them to 0. Steps other than steps 3 and 4 are the same as the steps shown in FIG.
　推定電圧Ｖｎは、算出された角周波数ωｎと、公知の式ω＝２πｆと、既知の定数Ｖ／ｆとから算出することができる。次に、推定電圧Ｖｎと出力電圧Ｖｉとの差の絶対値（大きさ）が所定の値と比較される（ステップ４）。推定電圧Ｖｎと出力電圧Ｖｉとの差の絶対値（大きさ）が所定の値以上である場合には、算出された角周波数ωおよび位相θｎは破棄され、角周波数ωｎおよび位相θｎは０に設定される（ステップ５）。そして、０に設定された角周波数ωｎおよび位相θｎがベクトル制御部３０に送られる（ステップ６）。 The estimated voltage V n can be calculated from the calculated angular frequency ω n , a known formula ω = 2πf, and a known constant V / f. Next, the absolute value (magnitude) of the difference between the estimated voltage V n and the output voltage V i is compared with a predetermined value (step 4). If the absolute value (magnitude) of the difference between the estimated voltage V n and the output voltage V i is greater than or equal to a predetermined value, the calculated angular frequency ω and phase θ n are discarded, and the angular frequency ω n and phase θ n is set to 0 (step 5). Then, the angular frequency ω n and the phase θ n set to 0 are sent to the vector control unit 30 (step 6).
　一方、推定電圧Ｖｎと出力電圧Ｖｉとの差の絶対値が所定の値よりも小さい場合には、算出された角周波数ωｎおよび特定された位相θｎがベクトル制御部３０に送られる（ステップ６）。ベクトル制御部３０は、角周波数ωｎおよび位相θｎに基づいてインバータ１０への電圧指令値Ｖｕ*，Ｖｖ*、Ｖｗ*を生成する。インバータ１０は、自由回転しているモータの誘起電圧の位相および周波数に同期した電圧をモータに出力する。 On the other hand, when the absolute value of the difference between the estimated voltage V n and the output voltage V i is smaller than a predetermined value, the calculated angular frequency ω n and the specified phase θ n are sent to the vector control unit 30. (Step 6). The vector control unit 30 generates voltage command values Vu *, Vv *, Vw * to the inverter 10 based on the angular frequency ω n and the phase θ n . The inverter 10 outputs a voltage synchronized with the phase and frequency of the induced voltage of the freely rotating motor to the motor.
　上述した実施形態は、本発明が属する技術分野における通常の知識を有する者が本発明を実施できることを目的として記載されたものである。上記実施形態の種々の変形例は、当業者であれば当然になしうることであり、本発明の技術的思想は他の実施形態にも適用しうることである。したがって、本発明は、記載された実施形態に限定されることはなく、特許請求の範囲によって定義される技術的思想に従った最も広い範囲に解釈されるものである。 The above-described embodiments are described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.
　本発明は、ロータの位置センサを用いることなく、モータを駆動することができる電力変換装置に適用可能である。 The present invention can be applied to a power converter that can drive a motor without using a rotor position sensor.
　１　　商用電源
　５　　電力変換装置
１０　　インバータ
１１　　コンバータ回路
１２　　インバータ回路
１３　　ゲートドライブ部
１５　　センサ部
１６　　インバータ制御部
１７　　記憶部
１９　　操作通信部
２０　　電流測定部
２１　　電圧測定部
３０　　ベクトル制御部
５０　　同期始動制御部
５１Ａ，５１Ｂ　　線間電圧比較器
５２Ａ，５２Ｂ　　パルスエッジ検出部
５５　　速度算出部 DESCRIPTION OF SYMBOLS 1 Commercial power supply 5 Power converter 10 Inverter 11 Converter circuit 12 Inverter circuit 13 Gate drive part 15 Sensor part 16 Inverter control part 17 Memory | storage part 19 Operation communication part 20 Current measurement part 21 Voltage measurement part 30 Vector control part 50 Synchronous start control part 51A, 51B Line voltage comparators 52A, 52B Pulse edge detector 55 Speed calculator

Claims (3)

  1. 　モータを駆動するための電力変換装置であって、
    　前記モータの誘起電圧を測定する電圧測定器と、
    　前記モータに可変周波数の電力を供給するインバータと、
    　前記インバータの出力電力を制御するベクトル制御部と、
    　測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、
    　前記同期始動制御部は、前記誘起電圧が予め設定された値以下であるときは、前記決定されたモータの位相および回転速度を破棄し、前記誘起電圧が前記予め設定された値よりも大きいときは、前記決定されたモータの位相および回転速度を前記ベクトル制御部に送ることを特徴とする電力変換装置。     A power conversion device for driving a motor,
    A voltage measuring device for measuring the induced voltage of the motor;
    An inverter for supplying variable frequency power to the motor;
    A vector control unit for controlling the output power of the inverter;
    A synchronous start control unit that determines the phase and rotation speed of the motor from the measured induced voltage,
    The synchronous start control unit discards the determined phase and rotational speed of the motor when the induced voltage is equal to or less than a preset value, and the induced voltage is greater than the preset value. Sends the determined phase and rotational speed of the motor to the vector control unit.
  2. 　モータを駆動するための電力変換装置であって、
    　前記モータの誘起電圧を測定する電圧測定器と、
    　前記モータに可変周波数の電力を供給するインバータと、
    　前記インバータの出力電力を制御するベクトル制御部と、
    　測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、
    　前記同期始動制御部は、前記決定されたモータの回転速度を周波数に換算して推定周波数を取得し、前記誘起電圧と前記モータに固有の比例定数Ｖ／ｆとから出力周波数を算出し、前記出力周波数と前記推定周波数との差が所定の値以上であるときは、前記決定されたモータの位相および回転速度を破棄し、前記出力周波数と前記推定周波数との差が前記所定の値よりも小さいときは、前記決定されたモータの位相および回転速度を前記ベクトル制御部に送ることを特徴とする電力変換装置。     A power conversion device for driving a motor,
    A voltage measuring device for measuring the induced voltage of the motor;
    An inverter for supplying variable frequency power to the motor;
    A vector control unit for controlling the output power of the inverter;
    A synchronous start control unit that determines the phase and rotation speed of the motor from the measured induced voltage,
    The synchronous start control unit obtains an estimated frequency by converting the determined rotational speed of the motor into a frequency, calculates an output frequency from the induced voltage and a proportional constant V / f specific to the motor, When the difference between the output frequency and the estimated frequency is greater than or equal to a predetermined value, the determined phase and rotational speed of the motor is discarded, and the difference between the output frequency and the estimated frequency is less than the predetermined value. When it is smaller, the power conversion device sends the determined phase and rotational speed of the motor to the vector control unit.
  3. 　モータを駆動するための電力変換装置であって、
    　前記モータの誘起電圧を測定する電圧測定器と、
    　前記モータに可変周波数の電力を供給するインバータと、
    　前記インバータの出力電力を制御するベクトル制御部と、
    　測定された前記誘起電圧から前記モータの位相および回転速度を決定する同期始動制御部とを備え、
    　前記同期始動制御部は、前記決定されたモータの回転速度を周波数に換算し、得られた前記モータの周波数と前記モータに固有の比例定数Ｖ／ｆとから推定電圧を算出し、前記誘起電圧と前記推定電圧との差が所定の値以上であるときは、前記決定されたモータの位相および速度を破棄し、前記誘起電圧と前記推定電圧との差が前記所定の値よりも小さいときは、前記決定されたモータの位相および速度を前記ベクトル制御部に送ることを特徴とする電力変換装置。     A power conversion device for driving a motor,
    A voltage measuring device for measuring the induced voltage of the motor;
    An inverter for supplying variable frequency power to the motor;
    A vector control unit for controlling the output power of the inverter;
    A synchronous start control unit that determines the phase and rotation speed of the motor from the measured induced voltage,
    The synchronous start control unit converts the determined rotational speed of the motor into a frequency, calculates an estimated voltage from the obtained motor frequency and a proportional constant V / f specific to the motor, and generates the induced voltage. When the difference between the estimated voltage and the estimated voltage is equal to or greater than a predetermined value, the determined phase and speed of the motor are discarded, and when the difference between the induced voltage and the estimated voltage is smaller than the predetermined value The power conversion apparatus, wherein the determined phase and speed of the motor are sent to the vector control unit.
PCT/JP2012/058890 2011-03-31 2012-04-02 Electric power conversion device for driving motor WO2012133887A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014231823A (en) * 2013-05-30 2014-12-11 株式会社荏原製作所 Pump device
US9705438B2 (en) 2015-07-14 2017-07-11 Infineon Technologies Austria Ag Controller for a free-running motor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004159500A (en) * 2004-03-08 2004-06-03 Hitachi Ltd Method for rebooting from momentary power failure
JP2011019348A (en) * 2009-07-09 2011-01-27 Hitachi Ltd Device and method for controlling permanent magnet synchronous motor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004159500A (en) * 2004-03-08 2004-06-03 Hitachi Ltd Method for rebooting from momentary power failure
JP2011019348A (en) * 2009-07-09 2011-01-27 Hitachi Ltd Device and method for controlling permanent magnet synchronous motor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014231823A (en) * 2013-05-30 2014-12-11 株式会社荏原製作所 Pump device
US9705438B2 (en) 2015-07-14 2017-07-11 Infineon Technologies Austria Ag Controller for a free-running motor

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JP2012213265A (en) 2012-11-01

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