JP7194033B2 - Power conversion device and its step-out determination method - Google Patents

Description

The present invention relates to a power conversion device and a step-out determination method thereof.

Permanent magnet synchronous motors, which are more efficient than conventional induction motors, are widely used in the industrial field. A permanent magnet synchronous motor rotates by inputting a rotating magnetic field so as to synchronize with the magnetic pole positions of the permanent magnets in the rotor. If the magnetic pole position and the rotating magnetic field are not synchronized, the rotor will not rotate and will be out of step, making control impossible. Therefore, in order to control the operation of the permanent magnet synchronous motor, a power converter capable of detecting the magnetic pole position is required.
Magnetic pole position detection means includes, for example, a magnetic pole position sensor. Magnetic pole position sensors include encoders, resolvers, Hall elements, and the like. Position information is detected by the magnetic pole position sensor at least twice per one rotation of the rotor, and input to the power converter to control the operation while recognizing the magnetic pole position.

On the other hand, in recent years, there are cases where operation control is performed by a magnetic pole position sensorless system in which the magnetic pole position sensor is omitted. In the magnetic pole position sensorless method, the permanent magnet synchronous motor is controlled while estimating the magnetic pole position from, for example, the phase of the detected current. Children may become out of sync and out of sync.
If a magnetic pole position sensorless method for estimating the magnetic pole position is in a step-out state, it may not be possible to estimate the step-out. be.

As a conventional technology for detecting step-out, as part of claim 1 of Patent Document 1, "the angular difference between the angular position of the magnetic axis of the rotor obtained based on the detection signal of the magnetic pole position sensor and the angle of the rotating magnetic field is "out-of-step detector for detecting whether or not a predetermined set value is exceeded", and discloses a technique for detecting out-of-step in a motor speed control device.

In addition, as part of claim 1 of Patent Document 2, "axis error for estimating the axis error between the control axis and the rotor magnetic pole axis of the synchronous motor based on the voltage command and the current detected by the current detector. an estimator, a frequency component extractor for extracting an arbitrary frequency component of the axis error estimated by the axis error estimator, and a desynchronizer for determining whether or not step-out occurs based on the frequency component extracted by the frequency component extractor. Synchronization Judgment", and discloses a technique related to out-of-step judgment in a power conversion device.

In addition, as part of claim 1 of Patent Document 3, "A starting excitation pattern of a phase that can generate maximum torque with respect to the position of the rotor at the time of starting is energized for the initial energization time to the brushless motor to rotate the rotor. an energization pattern determining means for causing the rotor of the brushless motor to free-run by stopping the energization by setting the duty of the pulse modulation signal to 0% after the speed is gradually increased; Excitation Switching Timing Calculation Means for Determining Excitation Timing by Detecting Rotor Position from Generated Induced Voltage", and discloses a technique for a start-up method in a brushless motor drive device.

In addition, in claim 1 of Patent Document 4, "Frequency for generating a digital signal having information on the rotation speed, rotation direction and magnetic pole position of the rotating machine based on the induced voltage of the rotating machine when the rotating machine is in the free running state a detector, a speed reproducer for estimating the rotational speed, rotational direction, and magnetic pole position of the rotating machine based on the digital signal generated by the frequency detector, and the rotational speed and rotational direction estimated by the speed reproducer. and a step-out determination unit that determines the step-out state of the rotating machine based on the magnetic pole position", and discloses a technology for determining the step-out state in the free running state using the power converter. It is

JP-A-2000-295886 JP 2014-147239 A JP 2014-33616 A JP 2017-28922 A

However, in the technique disclosed in Patent Document 1, three signals Pu, Pv, and Pw are detected from the magnetic pole position sensor in order to detect step-out, and a sensor capable of detecting the three-phase magnetic pole position is required. As a result, there is a problem (problem) that cost increase is unavoidable.

Further, the technique disclosed in Patent Document 2 has a problem (problem) that there is a possibility that step-out cannot be detected when the rotor rotates even slightly due to, for example, harmonic components of the applied voltage command frequency.

Further, the technique disclosed in Patent Document 3 is intended to stabilize startup, but there is a possibility that step-out may occur when an impact load is applied during startup or due to load fluctuations other than during startup. have no means of detection. Also, three comparators are required for the induced voltage detection circuit, which poses a problem (problem) of increased cost.

Further, the technology disclosed in Patent Document 4 detects the induced voltage in the starting, stopping, and free-running states, and re-accelerates the engine. As a result, the output current increases, and there is a risk that the overcurrent level will not fall within the design value. Therefore, there is a problem (problem) that the effective detection area is limited to the low speed operation area.

The present invention has been invented in view of the above-described problems, and is an electric power generator capable of detecting step-out with high reliability without using a magnetic pole position detection sensor or an induced voltage detection circuit in a high-speed operation range. An object (object) is to provide a converter and a control method for a power converter.

In order to solve the above problems, the present invention is configured as follows.
That is, the power conversion apparatus of the present invention includes a rectifier that converts the AC voltage of an AC power supply to a DC voltage, a smoothing capacitor that smoothes the DC voltage rectified by the rectifier, and a DC voltage across the smoothing capacitor to the AC voltage. and an inverter control unit for controlling the inverter unit, wherein the inverter control unit includes a PWM control unit for controlling the switching operation of the inverter unit, and a rotation driven by the output of the inverter unit. a speed command unit for generating a speed command based on a pressure command requested by a fluid machine host device of a fluid machine connected to the machine; a DC voltage detection value of the voltage of the smoothing capacitor; the pressure command; and a step-out determination unit that determines the step-out of the rotating machine based on the above, and cuts off the PWM control signal of the PWM control unit by the step-out determination of the step-out determination unit. .

Further, in the step-out determination method of the present invention, the speed command unit provided in the power conversion device is based on the pressure command requested by the fluid machine host device of the fluid machine connected to the rotating machine driven by the power conversion device. , a speed command is generated, and the storage unit provided in the power conversion device stores the determination speed command, determination pressure command, out-of-step determination voltage, and out-of-step determination of the out-of-step determination process set value group set by the setting input unit. A step-out determination unit that stores various determination conditions for time and that is provided in the power conversion device stores a DC voltage detection value of the voltage of the smoothing capacitor of the power conversion device and the determination conditions stored in the storage unit. and determining out-of-step of the rotating machine by referring to the pressure command and the speed command.

Other means are also described in the detailed description.

ADVANTAGE OF THE INVENTION According to the present invention, in a high-speed operation region, a power conversion device and a step-out determination method for a power conversion device that enable highly reliable detection of step-out without using a magnetic pole position detection sensor or an induced voltage detection circuit. can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the example of a structure of the power converter device which concerns on 1st Embodiment of this invention, and an example of relationship with an alternating current power supply, a rotary machine, a fluid machine, a fluid machine host device, and a pressure detection part. It is a figure which shows the circuit structural example of the DC voltage detection part in the power converter device which concerns on 1st Embodiment of this invention. FIG. 4 is a diagram showing a voltage waveform example of the output voltage of the DC voltage detection section according to the first embodiment of the present invention when the rotating machine is normally operating under a rated load. 3B is an enlarged view of a ripple component portion of the voltage waveform of FIG. 3A; FIG. FIG. 5 is a diagram showing an example voltage waveform of the output voltage of the DC voltage detection section according to the first embodiment of the present invention when the rotating machine is out of step and operated under rated load. FIG. 4B is an enlarged view of a ripple component portion of the voltage waveform of FIG. 4A; FIG. 4 is a diagram showing an example of a flowchart of internal processing of a step-out determining unit in the power converter according to the first embodiment of the present invention; FIG. 10 is a diagram showing an example of a flowchart of internal processing of a step-out determining unit in the power conversion device according to the second embodiment of the present invention; FIG. 11 is a diagram showing an example of a flowchart of internal processing of a step-out determining unit in the power converter according to the third embodiment of the present invention; FIG. 10 is a diagram showing an example of a voltage waveform of the output voltage of the DC voltage detection section according to the fourth embodiment of the present invention when the rotating machine is normally operating under a rated load. 8B is an enlarged view of a ripple component portion of the voltage waveform of FIG. 8A; FIG. FIG. 11 is a diagram showing an example of a voltage waveform of the output voltage of the DC voltage detection section according to the fourth embodiment of the present invention when the rotating machine is out of step and operated under rated load. FIG. 9B is an enlarged view of a ripple component portion of the voltage waveform of FIG. 9A; FIG. 12 is a diagram showing an example of a flowchart of internal processing of a step-out determining unit in the power converter according to the fourth embodiment of the present invention;

EMBODIMENT OF THE INVENTION Hereinafter, the form (it is described as "embodiment" below) for implementing this invention is demonstrated with reference to drawings suitably.
Note that the following description also serves as a description of the power conversion device and a description of its out-of-step determination method.

<< 1st embodiment, power converter >>
A power converter according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.
FIG. 1 shows a configuration example of a power converter 1 according to the first embodiment of the present invention, an AC power supply 201, a rotating machine (M: motor) 202, a fluid machine 203, a fluid machine host device 204, and a pressure detection unit 213. is a diagram showing an example of the relationship between.

<<Relationship between power conversion device 1 and related equipment>>
In FIG. 1, the power converter 1 receives an AC voltage (AC power) from a three-phase AC power supply 201 and converts it into a three-phase AC voltage (three-phase AC power) having a predetermined frequency and voltage. A rotary machine (M) 202 is driven by the converted three-phase AC voltage (three-phase AC power), and a fluid machine 203 such as a pump and a compressor connected to the rotary machine 202 operates.
Further, the fluid machine 203 is provided with a pressure detection unit 213 for detecting the pressure of the fluid machine 203 . A pressure detection value 2101 detected by the pressure detection unit 213 is sent to the fluid machinery host device 204 . Then, the pressure command unit 214 provided in the fluid machine host device 204 converts the pressure detection value 2101 into a pressure command 2001 . The fluid machine host device 204 is a host device for controlling the fluid machine 203 .
A pressure command 2001 output from the fluid machinery host device 204 is input to the inverter control section 14 of the power converter 1 .

<<Configuration of Power Conversion Device 1>>
The power conversion device 1 includes a rectifier 11 , a smoothing capacitor 12 , an inverter section (inverter circuit, DC/AC converter) 13 , an inverter control section 14 and a DC voltage detection section 15 . A detailed configuration of the inverter control unit 14 will be described later.
The rectifier 11 forms a three-phase diode bridge with a plurality of diodes, and rectifies three-phase AC voltage (AC power) into DC voltage (DC power). A smoothing capacitor 12 smoothes the rectified DC voltage.
The inverter section (inverter circuit) 13 is configured with a plurality of switching elements (not shown), and the plurality of switching elements is a PWM control section 145 using PWM (Pulse Width Modulation) in the inverter control section 14 described later. is controlled by the PWM control signal 2008 of .

By the control operation of the PWM control unit 145, the inverter unit 13 converts the DC voltage (DC power) supplied (input) from the rectifier 11 and the smoothing capacitor 12 into a three-phase AC voltage (three-phase AC power) having a predetermined frequency and voltage. ) and output.
As described above, the rotating machine 202 is driven by the three-phase AC voltage (three-phase AC power) output from the inverter section 13 .
In addition, the DC voltage detection unit 15 inputs the voltage across the smoothing capacitor 12, divides and averages the voltage, and uses the information of the fluctuating DC voltage as the DC voltage detection value 2005 to determine step-out of the inverter control unit 14. It is input to the part 143. A detailed configuration of the DC voltage detection unit 15 will be described later with reference to FIG.

<<Inverter control unit 14>>
The inverter control unit 14 is configured by, for example, a microcomputer included in the power converter 1, and operates by processing inside the microcomputer.
The inverter control unit 14 includes a setting input unit 141 , a storage unit 142 , a step-out determination unit 143 , a cutoff unit 144 , a PWM control unit 145 and a speed command unit 146 .

The setting input unit 141 has a function of inputting information such as a set value group 2003 for out-of-step determination processing, which will be described later, necessary for the determination operation of the out-of-step determination unit 143 to the storage unit 142 based on the external information signal 2013 . .
For example, the determination speed command A, the determination pressure command B, the out-of-step determination voltage (upper limit side) C, the out-of-step Various set conditions 2004 such as the tuning determination voltage (lower limit side) D, the out-of-step determination time E, etc. are stored.
As described above, the pressure command 2001 is input to the inverter control unit 14 from the pressure command unit 214 provided in the fluid machine host device 204 .
Pressure command 2001 is input to speed command section 146 and step-out determination section 143 .
A speed command unit 146 calculates a speed command 2002 based on the pressure command 2001 and outputs the speed command 2002 to the step-out determination unit 143 and the PWM control unit 145 .
PWM control section 145 generates PWM control signal 2008 based on this speed command 2002 and controls inverter section 13 .

Note that the speed command unit 146 calculates and generates the speed command 2002 based on the pressure command 2001 of the pressure command unit 214 as described above.
When calculating the speed command 2002 from the pressure command 2001, the speed command unit 146 generates the pressure command 2001 so that the fluid machinery host device 204 satisfies the pressure command 2001. FIG. Specifically, speed command unit 146 generates speed command 2002 using proportional control (P control) or integral control (I control).

A pressure command 2001 and a speed command 2002 are input to the out-of-step determination unit 143 . Further, the out-of-step determination unit 143 stores, for example, the aforementioned determination speed command A, determination pressure command B, out-of-step determination voltage (upper limit side) C, out-of-step determination voltage (lower limit side) D, The set conditions (determination conditions and threshold values) 2004 such as the out-of-step determination time E are referred to as appropriate. Note that each set value of the set conditions 2004 is appropriately adjusted depending on the receiving voltage, the magnitude of the load on the rotating machine 202 and the fluid machinery 203, the capacitance value of the capacitor 152, the efficiency of the fluid machinery 203, and the like. and
A DC voltage detection value 2005 , which is information on a varying DC voltage from the DC voltage detection unit 15 , is input to the step-out determination unit 143 .
The out-of-step determination unit 143 determines whether the rotating machine 202 is out of step based on the pressure command 2001, the speed command 2002, the setting conditions 2004 of the out-of-step determination processing setting value group 2003, and the DC voltage detection value 2005. determine whether

The details of step-out determination will be described later with reference to characteristic diagrams of voltage waveforms in FIGS. 3A, 3B, 4A, and 4B and a flowchart shown in FIG.
When the step-out determination unit 143 determines that the rotating machine 202 is out of step, it sends a step-out determination signal 2006 to the blocking unit 144 .
The cutoff unit 144 sends a cutoff signal 2007 to the PWM control unit 145 when the out-of-step determination signal 2006 is received from the out-of-step determination unit 143 .
The PWM control unit 145 stops the PWM control operation when the cutoff signal 2007 is received.

<<Regarding the DC voltage detector 15>>
A detailed configuration of the DC voltage detection unit 15 will be described with reference to FIG.
FIG. 2 is a diagram showing a circuit configuration example of the DC voltage detector 15 in the power converter 1 according to the first embodiment of the present invention.
In FIG. 2, the DC voltage detector 15 is configured with a voltage dividing resistor 151 and a capacitor 152 .
The voltage dividing resistor 151 is composed of a series circuit of a resistive element 151A, a resistive element 151B, and a resistive element 151C.
The voltage across smoothing capacitor 12 (FIGS. 1 and 2) is divided by resistive elements 151A, 151B, and 151C, and the voltage across resistive element 151C is smoothed (averaged) by capacitor 152. FIG.

A voltage Vdet across the capacitor 152 is detected as a DC voltage detection value 2005 (voltage Vdet). The voltage Vdet (detected DC voltage value 2005) is smoothed (averaged) by the capacitor 152 and converted into a DC voltage. It contains a ripple component (analog signal).
The DC voltage detection unit 15 detects the charge/discharge voltage of the smoothing capacitor 12 by the function of the circuit configuration described above, and outputs the DC voltage detection value 2005 used for the step-out determination by the step-out determination unit 143 to the step-out determination unit 143. (Fig. 1).

<Regarding the principle of step-out detection (judgment)>
Next, the principle of out-of-step detection (determination) in the out-of-step determination section 143 will be described with reference to FIGS. 3A, 3B, 4A, and 4B.

《Voltage waveform of the DC voltage detector when the rotating machine is operating normally》
3A and 3B show the DC voltage when the rotating machine 202 (M: FIG. 1) is operating normally under the rated load in the DC voltage detection unit 15 (FIG. 2) according to the first embodiment of the present invention. FIG. 3 is a diagram showing a voltage waveform example of a voltage Vdet (2005: FIG. 2, 3001: FIGS. 3A and 3B), which is the output voltage of the voltage detection unit 15;
3A and 3B, the horizontal axis is time [t] and the vertical axis is voltage [Vdc]. The suffix dc to the voltage [Vdc] and V indicates a DC voltage.

A characteristic line 3001 (Vdet) of the voltage waveform shown in FIG. 3A is a voltage waveform obtained by rectifying AC power supply 201 (FIG. 1) by rectifier 11 (FIG. 1) and smoothing by smoothing capacitor 12 .
The voltage waveform indicated by characteristic line 3001 is the voltage waveform across smoothing capacitor 12 . A characteristic line 3002 indicated by a dashed line for reference is the voltage across the smoothing capacitor 12 (FIG. 2) when the smoothing capacitor 12 is not present.
A characteristic line 3001 reflects the voltage waveform of the smoothing capacitor 12 in FIG.
A characteristic line 3001 is input to the DC voltage detection unit 15 (FIG. 2), where the voltage is divided by the voltage dividing resistor 151 (FIG. 2) and further smoothed by the capacitor 152 (FIG. 2). averaging), Vdet has less ripple components than the characteristic line 3001 .
A characteristic line 3002 generally reflects the voltage waveform across the smoothing capacitor 12 in FIG. 2, although the absolute values of the voltages are different. That is, the rectifier 11 rectifies, the smoothing capacitor 12 smoothes, and the waveform of the DC voltage including the ripple component input to the inverter section 13 is reflected.

A characteristic line 3001 indicated by a solid line and a characteristic line 3002 indicated by a broken line represent states in which the ripple component of the AC power supply 201 remains in the voltage waveform. Note that the interval Tc, which is one interval of this ripple component, is (1/(50×2×3)) seconds when the AC power supply 201 is 50 Hz, and (1/(60×2 x 3)) seconds. Also, the denominator (2×3) in the above fraction reflects the configuration of the rectifier 11 (FIG. 1).
Also, the characteristic line 3002 shows the voltage waveform across the smoothing capacitor 12 (FIG. 2) as a reference, as described above. Since the characteristic line 3001 is the voltage waveform without the capacitor 152, the fluctuation of the ripple component is displayed to be larger than that of Vdet.

3A, the center value (typ) of the characteristic line 3001, which is the voltage waveform across the capacitor 152 (FIG. 2), is ΔVtyp (3010), the maximum value (max) is ΔVmax (3011), and the minimum The value (min) is ΔVmin (3012).
ΔVmax, ΔVmin, and ΔVtyp relate to fluctuations in the voltage of the AC power supply 201 and also to whether the rotating machine 202 is operating normally or out of step. In other words, as will be described later in detail, depending on whether the rotating machine 202 is operating normally or out of step, the power (energy) it consumes will differ, and the voltage waveform will also be affected.

FIG. 3B is an enlarged view of the ripple component portion of the voltage waveform of FIG. 3A.
In FIG. 3B, the out-of-step determination voltage (upper limit) C and the tuning determination voltage (lower limit) D are simply indicated as determination value C (3021) and determination value D (3022), respectively. It should be noted that, also in the following description, they are appropriately referred to as a judgment value C and a judgment value D, respectively.
Determination value C (out-of-step determination voltage (upper limit) 3021) and determination value D (out-of-step determination voltage (lower limit) 3022) are determined by step-out determination unit 143 (FIG. 1) when rotating machine 202 (FIG. 1) is This is a criterion used when determining whether or not there is a step-out.
In the case of FIG. 3B, ΔVmin is lower than the determination value D, so the rotary machine 202 rotates sufficiently to consume electric power, resulting in a large voltage fluctuation. That is, it is shown that it is a situation in which it is determined that there is no step-out.
In FIG. 3B, the characteristic lines 3001, 3002, ΔVtyp, ΔVmax, ΔVmin, and Tc are the same as those in FIG. 3A, and redundant description will be omitted.

《Voltage waveform of the DC voltage detector when the rotating machine is out of step》
4A and 4B show the case where the rotating machine 202 (M: FIG. 1) is out of step at the rated load in the DC voltage detection unit 15 (FIG. 2) according to the first embodiment of the present invention. 2 is a diagram showing a voltage waveform example of a voltage Vdet (2005: FIG. 2, 4001: FIGS. 4A and 4B), which is the output voltage of the DC voltage detection unit 15 in .
4A and 4B, the horizontal axis is time [t] and the vertical axis is voltage [Vdc].

The voltage waveform shown by the characteristic line 4001 in FIG. 4A is a voltage waveform obtained by rectifying the AC power supply 201 (FIG. 1) by the rectifier 11 (FIG. 1) and smoothing it by the smoothing capacitor 12, as shown in FIG. 3A. . The characteristic line 4001 is the voltage Vdet of the detected voltage waveform input to the DC voltage detector 15 ( FIG. 2 ) and taken out as the output of the DC voltage detector 15 . In the DC voltage detection unit 15, the voltage is divided by the voltage dividing resistor 151 (FIG. 2) and further smoothed by the capacitor 152 (FIG. 2).
The voltage waveform indicated by the characteristic line 4001 is the voltage waveform across the smoothing capacitor 12 and is the voltage Vdet of the detected voltage waveform. It should be noted that the voltage Vdet of the detected voltage waveform fluctuates and contains ripple components.

Also, a characteristic line 4002 indicates, for reference, the voltage waveform across the smoothing capacitor 12 (FIG. 2) when the smoothing capacitor 12 is not present. A characteristic line 4001 indicates the voltage waveform without the capacitor 152, so the fluctuation of the ripple component is large compared to Vdet.
The center value (typ) of the characteristic line 4001, which is the voltage waveform across the capacitor 152 (FIG. 2), is ΔVtyp (4010), the maximum value (max) is ΔVmax (4011), and the minimum value (min) is ΔVmin. (4012).
Note that the ripple component of the voltage waveform in the characteristic lines 4001 and 4002 and the section Tc, which is one section of this ripple component, are the same as those in FIG. 3A, so redundant description will be omitted.

FIG. 4B is an enlarged view of the ripple component portion of the voltage waveform of FIG. 4A.
FIG. 4B shows determination value C (out-of-step determination voltage (upper limit) 4021) and determination value D (out-of-step determination voltage (lower limit) 4022).
The determination value C and the determination value D are determination criteria used when the step-out determining unit 143 (FIG. 1) determines whether or not the rotating machine 202 (FIG. 1) is out of step.
In the case of FIG. 4B, ΔVmin is never less than the determination value D, which indicates that the rotating machine 202 does not consume much power (energy) and rotates with little voltage fluctuation. there is That is, this is a situation in which it is determined that the rotating machine 202 is operating out of step.

The determination value C (upper limit side) and the determination value D (lower limit side), which are the out-of-step determination voltages (upper limit side and lower limit side), are determined by the actual output of the rotating machine 202 and the capacitance of the smoothing capacitor 12. , and depends on the received power voltage (the voltage of the AC power supply 201).
In addition, in FIG. 4B, characteristic lines 4001, 4002, ΔVtyp, ΔVmax, ΔVmin, and Tc are the same as those in FIG. 4A, and duplicate descriptions are omitted.

<<Details of step-out detection>>
3A, 3B, 4, and 4B, the voltage waveforms of the DC voltage detection value (voltage Vdet) when step-out does not occur and when step-out occurs have been described. Next, the details of step-out detection will be further described from the voltage waveform of the actual voltage Vdet.

The actual output of the rotating machine 202 (FIG. 1) is the sum of active power P=√3×V×I×cos θ and reactive power Q=√3×V×I×sin θ.
The active power P almost occupies the ratio between the active power P and the reactive power Q during normal operation of the rotating machine 202 .
Conversely, the reactive power Q accounts for almost the ratio of the active power P and the reactive power Q when the rotating machine 202 is out of step.
Therefore, since rotating machine 202 consumes a large amount of power (active power) during normal operation, voltage Vdet fluctuates relatively greatly between ΔVmax and ΔVmin in order to supply the power.

On the other hand, the power during step-out operation in FIGS. 4A and 4B is almost non-existent compared to normal operation (FIGS. 3A and 3B). The deviation of the ripple voltage due to charging and discharging becomes smaller than that during normal operation (FIGS. 3A and 3B).
That is, a large ripple voltage between ΔVmax and ΔVmin as shown in FIGS. 3A and 3B does not occur, and the ripple voltage is relatively small and smooth, such as between ΔVmax and ΔVmin shown in FIGS. 4A and 4B. voltage.
Therefore, the step-out determination voltage ΔVmax and the upper and lower limits (determination value C, determination value D) related to ΔVmin are set to the step-out determination unit 143 (FIG. 1) by the pressure command 2001, speed command 2002, and Provided based on setting conditions 2004 of the determination processing setting value group 2003, the voltage detection value (voltage Vdet) of the DC voltage detection unit 15 is always between the upper limit (determination value C) and the lower limit (determination value D). If it is within the interval, it is determined that it is out of step. That is, it is possible to detect step-out.

<Regarding step-out determination of rotating machine 202>
Step-out determination of rotating machine 202 (FIG. 1) will be described in more detail.
In order to determine whether the rotary machine 202 is out of step, calculation is performed based on the detection value detected by the pressure command unit 214 in the fluid machine host device 204 of the fluid machine 203 (FIG. 1) such as a pump or compressor. The step-out determination unit 143 refers to the pressure command 2001 .
When the pressure command 2001 becomes the maximum value, the speed command 2002 generated by the speed command unit 146 based on the pressure command 2001 also becomes the maximum value. It is possible to estimate the actual output of the rotating machine 202 from the fastest value of the speed command 2002, and the ripple voltage due to charging and discharging of the smoothing capacitor 12 (FIGS. 1 and 2) at the maximum actual output of the rotating machine 202 is can be estimated.

Therefore, when the pressure command 2001 and the speed command 2002 are the maximum and fastest values, the DC voltage detection value of the DC voltage detection unit 15 for detecting the voltage charged in the smoothing capacitor 12 and the out-of-step determination process set value group (2003) out-of-step determination voltage (lower limit side determination value D), and out-of-step is detected. If it is out of step, protective operation is performed.
If it is determined that there is no step-out, the operation of the rotating machine 202 is continued.
The out-of-step determination process set value group (2003), which is the condition for detecting out-of-step, can be set in advance in the storage unit 142 or can be set to arbitrary values by the setting input unit 141 from the outside. These set values are appropriately adjusted according to the receiving voltage (AC power supply 201), the size of the rotating machine 202 and the load connected thereto, the capacity of the smoothing capacitor 12, and the efficiency of the fluid machinery 203, as described above. and
In order to describe the step-out determination of the rotating machine 202 in more detail, the operation of the step-out determination unit 143 will be described below with reference to a flowchart.

<Flow chart of the operation of the step-out determination unit 143>
FIG. 5 is a diagram showing an example of a flowchart of internal processing of the step-out determination unit 143 in the power converter according to the first embodiment of the present invention. Next, each step (process) of the flow chart will be described.

<Step S20>
When the out-of-step determination processing is started, first, in step S20, the set values included in the out-of-step determination processing set value group 2003 are read (set value read).
Specifically, input from the setting input unit 141, determination speed command A, determination pressure command B, out-of-step determination voltage (upper limit) C (determination value C), out-of-step determination voltage set in the storage unit 142 (Lower limit value) D (determination value D) and loss of synchronism determination time E are read into loss of synchronism determination unit 143 .

<Step S21>
At step S21, the rotating machine (M) 202 and the fluid machine 203 are operated. Further, the PWM control unit 145 and the inverter unit 13 are operated so that the power conversion device 1 outputs power (voltage).
As the fluid machine 203 operates, the pressure detection unit 213 sends the pressure detection value 2101 to the pressure command unit 214 of the fluid machine host device 204 . Pressure command unit 214 generates pressure command 2001 based on pressure detection value 2101 , and this pressure command 2001 is sent to inverter control unit 14 .

<Step S22>
In step S22, the speed command 2002 calculated based on the pressure command 2001 of the fluid machine host device 204 that controls the fluid machine 203 is greater than the judgment speed command A, and the pressure command 2001 of the pressure command unit 214 is the judgment pressure command. The loss of synchronism determination unit 143 determines whether it is greater than B. In other words, "speed command>A" and "pressure command>B" are determined.
Note that the pressure command 2001 and the speed command 2002 used for determination use the maximum value and the fastest value, respectively, at the time of determination.
If both determinations are satisfied (Yes), the process proceeds to step S23.
If either or none of them satisfy the determination (No), it is determined that there is no step-out, and the determination operation of the step-out determination unit 143 is terminated (End). In other words, the operation is continued without detection of step-out.

If either "speed command >A" or "pressure command >B" or neither of them satisfies the determination (No), the fluid machine host device 204 controls the fluid machine 203 to sufficiently operate within the desired range. Equivalent to working. In this situation, the fluid machine 203 and the rotary machine 202 are fully operating within the desired range, so there is no need to issue a large pressure command 2001 . In other words, it means that it is determined that the rotating machine 202 is sufficiently operating and therefore is not out of step. Also, the pressure command 2001 and the speed command 2002 are correlated. If the speed command is smaller than the judgment speed command A, it also means that the fluid machine 203 and the rotary machine 202 are sufficiently operating within the desired range.
From the above, as described above, if the pressure command 2001 is smaller than the judgment pressure command B or the speed command 2002 is smaller than the judgment speed command A, it is determined that there is no step-out. The determination operation of the determination unit 143 is ended (End). Then continue driving.

<Step S23>
In step S23, the ΔVmax value and the ΔVmin value are detected in the DC voltage detection unit 15, and the ΔVtyp value of the reference value is calculated. That is, the DC voltage value reference ΔVtyp is detected (DC voltage value reference detection (ΔVtyp)).
Then, the process proceeds to step S24.

<Step S24>
In step S24, the out-of-step determination voltage (lower limit) D used for out-of-step determination in the out-of-step determination unit 143, that is, the determination value D is corrected to set the determination value Ds.
The voltage Vdet (characteristic line 3001, characteristic line 4001) of the detected voltage waveform detected by the DC voltage detector 15 varies depending on the receiving voltage condition of the AC power supply 201, so the ripple voltage of the smoothing capacitor 12 fluctuates. The voltage Vdet, which is a voltage, also fluctuates.
Therefore, it is desirable to correct the out-of-step determination voltage (lower limit) D in accordance with fluctuations in the received voltage of the AC power supply 201 . Specifically, based on the DC voltage value reference (ΔVtyp) calculated in step S23, the determination value D, which is the step-out determination voltage (lower limit value) D, is corrected to the determination value Ds. A specific correction method for correcting the determination value D to the determination value Ds is set in advance in consideration of various factors.
Then, the process proceeds to step S25.

<Step S25>
In step S25, it is determined whether or not the voltage Vdet of the detected voltage waveform is lower than the corrected determination value Ds over a predetermined period of time.
However, as shown in FIG. 4B, since the determination value D is a predetermined fixed value, the corrected determination value Ds is also a predetermined fixed value. On the other hand, the voltage Vdet of the detected voltage waveform (characteristic lines 3001 and 4001) includes a ripple waveform and fluctuates in voltage value.
Therefore, the magnitude relationship between the voltage Vdet of the detected voltage waveform and the corrected determination value Ds may change depending on when and how long the comparison is performed.
If the relationship "Vdet<Ds" is detected (Yes), the voltage Vdet of the detected voltage waveform fluctuates greatly, that is, it can be determined that the rotating machine 202 operates normally and is not out of step. . That is, assuming that the rotating machine 202 is operating normally, the operation of the rotating machine 202 is continued, and the out-of-step determination unit process ends (End).

In step S25, even if the relationship "Vdet<Ds" is not determined (No), the voltage Vdet of the detected voltage waveform fluctuates as described above, so the determined timing and measurement are not appropriate. It is possible that
In this case (No), the process proceeds to step S26.

<Step S26>
In step S26, the time tm when "Vdet>Ds" is measured in the determination in step S25.
That is, it is a measurement for comparing the time tm in consideration of the ripple cycle time Tc of the voltage waveforms (characteristic lines) 3001 and 4001 in FIG. 3B or 4B.
After measuring the time tm, the process proceeds to step S27.

<Step S27>
In step S27, "time tm>E" is determined. Note that E is the out-of-step determination time. That is, it compares whether or not the time tm exceeds a predetermined out-of-step determination time E (time equal to or longer than Tc).
If the time tm exceeds the out-of-step determination time E (Yes), it is determined that Vdet>Ds for a sufficiently long time, and out-of-step is determined. Then, the process proceeds to step S28.
If the time tm does not exceed the out-of-step determination time E (No), it is assumed that there is no out-of-step, that is, the rotating machine 202 operates normally, and the operation of the rotating machine 202 is continued.
Then, the determination operation of the out-of-step determination unit 143 is ended (End).

<Step S28>
In the process leading to step S28, since the conditions for determination of out-of-step have been met, in step S28, an Err signal indicating that out-of-step has occurred is output (Err output).
The out-of-step determining unit 143 outputs an Err output signal to the blocking unit 144 (FIG. 1) (out-of-step determination signal 2006: FIG. 1), thereby ending the determining operation of the out-of-step determining unit 143 (End).
It should be noted that the cutoff unit 144 that has received the out-of-step signal stops the predetermined operation of the PWM control unit 145 with the cutoff signal 2007 .
Further, when an Err output signal is output from the out-of-step determination unit 143, a protection operation against other predetermined out-of-step is performed based on the Err output signal.

<Overview of the first embodiment>
As the power conversion device 1, in order to determine whether the rotating machine 202 is out of step, based on the pressure detection value 2101 detected by the pressure detection unit 213 of the fluid machine 203 such as a pump or compressor, the fluid machine host device A pressure command unit 214 at 204 outputs a pressure command 2001 to the inverter control unit 14 of the power converter 1 .
A speed command 2002 is generated by the speed command unit 146 of the inverter control unit 14 based on the pressure command 2001 .
It is determined whether or not the speed command 2002 or the pressure command 2001 is greater than their respective predetermined set values. If the rotary machine 202 operates and rotates normally, the pressure command 2001 and the speed command 2002 do not require large values. If the speed command 2002 or the pressure command 2001 is smaller than the respective predetermined set values, it means that the motor is operating normally, and no further process for determining out-of-step is necessary.

If the speed command 2002 or the pressure command 2001 is greater than their respective predetermined set values, it is assumed that there is a possibility of step-out. A certain ΔVmin is detected and an average value ΔVtyp is calculated.
Using this ΔVtyp, the voltage fluctuation of the AC power supply is corrected to the determination value D of the out-of-step determination voltage (lower limit side) D to generate the corrected determination value Ds, and the voltage Vdet detected by the DC voltage detection unit 15 is Loss of synchronism is detected by comparison with the judgment value Ds.

When the step-out determination unit 143 detects step-out, a protection operation such as stopping the rotating machine 202 is performed.
Further, if step-out is not detected, the operation of the rotating machine 202 is continued. Then, step-out detection is continued.
The set value group 2003 for detecting step-out, which is the condition for detecting step-out, can be set in advance in the storage unit 142 or can be set to an arbitrary value from the outside. It is adjusted appropriately according to the power receiving voltage, the size of the rotating machine 202 and the load connected thereto, the capacity of the smoothing capacitor 12, and the efficiency of the fluid machine 203. FIG.
By detecting out-of-step by the above configuration and method, it is possible to detect out-of-step with high reliability.

<Effects of the first embodiment>
According to the first embodiment of the present invention, in a high-speed operation region, a power conversion device that enables highly reliable out-of-step detection without using a magnetic pole position detection sensor or an induced voltage detection circuit, and a power conversion device. can provide a step-out determination method.

<<Second embodiment/power converter>>
A power converter according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment differs from the first embodiment in the control method of the inverter control section 14 (FIG. 1). Therefore, the operation of the out-of-step determination unit 143 (FIG. 1) in the second embodiment will be described with a flowchart.
FIG. 6 is a diagram showing an example of a flowchart of internal processing of the step-out determination unit 143 in the power converter according to the second embodiment of the present invention.
In FIG. 6, in order to prevent erroneous determination of out-of-step, the number of out-of-step determinations (upper limit) F and the number of out-of-step determinations (lower limit) G are introduced. Number counts S41 and S43, upper limit side excess number determination S42, and lower limit side excess number determination S44 are added.

<Steps S20 to S23>
Further, in the flowchart of FIG. 6, steps S20 to S23 are substantially the same as steps S20 to S23 of the flowchart of FIG. 5 shown in the first embodiment.
However, in reading the set values in step S20, the determination speed command A, the determination pressure command B, the out-of-step determination voltage (upper limit) C, the out-of-step determination voltage (lower limit) D, and the out-of-step determination set in the storage unit 142 are In addition to the determination time E, the out-of-step determination count (upper limit) F and the out-of-step determination count (lower limit) G are also read.
Other overlapping descriptions in steps S20 to S23 are omitted.

<Step S241>
Step S241 in the flowchart of FIG. 6 corresponds to step S24 in the flowchart of FIG. The determination voltage threshold correction in step S24 in FIG. 5 is a process (step) of correcting the determination value D, which is the out-of-step determination voltage (lower limit value), to the determination value Ds.
On the other hand, in step S241 of FIG. 6, the out-of-step determination voltage (upper limit, lower limit) used for out-of-step determination in the out-of-step determination unit 143 is corrected and set to the determination values (Cs, Ds). .
That is, the determination values (Cs, Ds) are set by correcting the determination value C to the determination value Cs and the determination value D to the determination value Ds.
The step-out determination voltage (upper limit) C is corrected based on the DC voltage value reference ΔVtyp calculated in step S23, and the corrected determination value Cs is set.
Further, the step-out determination voltage (lower limit value) D is corrected based on the DC voltage value reference ΔVtyp calculated in step S23, and the corrected determination value Ds is set.

<Step S34>
In step S34, the upper limit side voltage of the voltage Vdet of the detected voltage waveform is determined. That is, the voltage Vdet of the detected voltage waveform is compared and determined with the determination value Cs corrected and set in step S241.
If the voltage Vdet of the detected voltage waveform is equal to or less than the corrected determination value Cs, which is the out-of-step determination voltage (upper limit side) (Yes), the process proceeds to step S35.
When the voltage Vdet of the detected voltage waveform exceeds the determination value Cs (No), the process proceeds to step S41.
Step S35 will be described later. First, step S41 will be described.

<Step S41>
In step S41, the number of times the voltage Vdet of the detected voltage waveform exceeds the upper limit judgment value Cs is counted, and the process proceeds to step S42.

<Step S42>
In step S42, it is determined whether or not the number of times the voltage Vdet of the detected voltage waveform exceeds the upper limit judgment value Cs in step S41 exceeds a predetermined out-of-step judgment number (upper limit) F. . In other words, it is determined that "the number of times of excess on the upper limit side>F".
If the number of times exceeding the upper limit side exceeds the number of times of loss of synchronism determination (upper limit side) F (Yes), the process returns to step S23, the DC voltage detector 15 detects the ΔVmax value and the ΔVmin value, and determines the reference value ΔVtyp. Redo the value calculation.
That is, since the received power voltage of the AC power supply 201 has increased and the ΔVmax value has increased, it is determined that an appropriate determination has not been performed. Therefore, it was determined that it was necessary to re-detect the ΔVmax value and ΔVmin value and recalculate the ΔVtyp value of the reference value.

When the number of times of exceeding the upper limit side does not exceed the number of times of out-of-step determination (upper limit side) F in step S42 (No), the process proceeds to step S35.
The reason why the process proceeds to step S35 is that it is difficult to determine out-of-step only by determining the upper limit side voltage, and it is necessary to determine the lower limit side voltage.

<Step S35>
In step S35, it is determined whether or not the voltage Vdet of the detected voltage waveform is lower than the lower limit side determination value Ds in substantially the same manner as step S25 in FIG. 5 shown in the first embodiment.
As described above, the determination value Ds on the lower limit side is a predetermined fixed value, whereas the voltage Vdet of the detected voltage waveform fluctuates. Therefore, the magnitude relationship between the voltage Vdet of the detected voltage waveform and the judgment value Ds on the lower limit side changes depending on when and how long the comparison is performed.
If the voltage Vdet of the detected voltage waveform is not lower than the determination value Ds on the lower limit side (No), the process proceeds to step S36.
If the voltage Vdet of the detected voltage waveform is lower than the lower limit judgment value Ds (Yes), the process proceeds to step S43.
Step S43 will be described later.
Next, step S36 will be described. The following steps S36 to S38 generally correspond to steps S26 to S28 shown in FIG. 5 of the first embodiment.

<Step S36>
In step S36, the time tm when "Vdet>Ds" is measured in the determination in step S35. This measurement is for comparison in consideration of the ripple cycle time Tc of the voltage waveforms (characteristic lines) 3001 and 4001 in FIG. 3B or 4B.
After measuring the time tm, the process proceeds to step S37.

<Step S37>
In step S37, "time tm>E" is determined. Note that E is the out-of-step determination time. If the time tm exceeds the out-of-step determination time E (Yes), it is determined that Vdet>Ds for a sufficiently long time, and out-of-step is determined. Then, the process proceeds to step S38.
If the time tm spent for the determination does not exceed the out-of-step determination time E (No), it is assumed that there is no out-of-step, that is, the rotating machine 202 operates normally, and the operation of the rotating machine 202 is continued.
Then, the determination operation of the out-of-step determination unit 143 (FIG. 1) ends (End).

<Step S38>
In the process leading to step S38, the conditions for determination of step-out have been met, so in step S38, an Err signal indicating that step-out has occurred is output.
The Err output signal terminates the determination operation of the out-of-step determination unit 143 (End).
Also, when the Err output signal is output, a step-out protection operation is performed.

<Step S43>
If the lower limit side voltage determination in step S35 is determined as No, the process proceeds to step S43. This step S43 will be described.
In step S43, the number of times the voltage Vdet of the detected voltage waveform exceeds the lower limit judgment value Ds is counted, and the process proceeds to step S44.

<Step S44>
In step S44, it is determined whether or not the number of times the voltage Vdet of the detected voltage waveform exceeds the lower limit judgment value Ds in step S43 exceeds a predetermined loss of synchronism judgment count (lower limit) G. . In other words, it is determined that "lower limit side excess count>G".
If the number of exceeding the lower limit exceeds the out-of-step determination number (lower limit) G (Yes), the process returns to step S23, the DC voltage detector 15 detects the Vmax value and the ΔVmin value, and the ΔVtyp value of the reference value is detected. redo the calculation of
That is, since the received voltage of the AC power supply 201 has decreased and the ΔVmin value has decreased, it is determined that the normal determination is not performed properly, and the voltage is detected again.

If the number of times exceeding the lower limit side does not exceed the out-of-step determination number (lower limit side) G (No), it is determined that the voltage received from the AC power supply 201 is within an appropriate range, and the determination operation of the flowchart is temporarily terminated. (End). Then, in the next out-of-step determination cycle, the operation of determining normality or out-of-step is performed again.

<Effects of Second Embodiment>
In the second embodiment, in addition to the out-of-step determination processing step of the first embodiment, a step S34 for upper limit side voltage determination is added. In the upper limit side voltage determination and the lower limit side voltage determination, number counts S41 and S43, upper limit side excess number determination S42, and lower limit side excess number determination S44 are provided, and measurement is performed in consideration of voltage fluctuations of the AC power supply 201. ing.
Therefore, even when the voltage of the AC power supply 201 fluctuates, the out-of-step determination is properly performed, and the accuracy of the out-of-step determination is improved.

<<Third embodiment/power converter>>
A power converter according to a third embodiment of the present invention will be described with reference to FIG. The third embodiment differs from the second embodiment (and the first embodiment) in the control method of the inverter control section 14 (FIG. 1). Therefore, the operation of the out-of-step determination unit 143 (FIG. 1) in the third embodiment will be described with a flowchart.
FIG. 7 is a diagram showing an example of a flow chart of internal processing of the step-out determining unit 143 in the power converter according to the third embodiment of the present invention.
In the flowchart shown in FIG. 7, steps of a method for preventing erroneous determination of out-of-step are as steps of a step-out determination accumulated time (excessive time accumulation) S51, an upper limit side accumulated time determination S52, and an out-of-step detection accumulated time (excessive time accumulation) S53. , the lower limit accumulated time determination S54 replaces the count S41, the upper limit excess count determination S42, the count S43, and the lower limit excess count determination S44 in the flowchart of FIG. 6 (second embodiment).
Except for these replaced steps, the flow chart of FIG. 7 (third embodiment) is substantially the same as the flow chart of FIG. 6 (second embodiment), so redundant description will be omitted as appropriate.

<Steps S20 to S23, Step 241>
In the flowchart of FIG. 7, steps S20 to S23 and step S241 are substantially the same as steps S20 to S23 and step S241 of the flowchart of FIG. 6 shown in the second embodiment.
In reading the set values in step S20, the determination speed command A, the determination pressure command B, the out-of-step determination voltage (upper limit) C, the out-of-step determination voltage (lower limit) D, and the out-of-step determination time set in the storage unit 142 are E is read in the same way.
However, instead of the out-of-step detection count (upper limit) F and the out-of-step detection count (lower limit) G, read the out-of-step detection integrated value (upper limit) H and the out-of-step detection integrated value (lower limit) I, respectively. I'm listening.

<Steps S34 to S38>
In the flowchart of FIG. 7, steps S34 to S38 are substantially the same as steps S34 to S38 of the flowchart of FIG. 6 shown in the second embodiment. Redundant explanations are omitted.

Steps S51 to S54 in FIG. 7, which are different from FIG. 6, will be described below.

<Step S51>
In the "excess time integration" of step S51 in FIG. 7, the voltage Vdet of the detected voltage waveform when the upper limit side voltage determination is No in the upper limit side voltage determination (S34) is corrected by the determination voltage threshold correction (S24). Accumulate the excess time exceeding the judgment voltage (upper limit side) Cs.
The process of accumulating overtime in step S51 in FIG. 7 corresponds to the process of counting the number of times in step S41 in FIG. 6, and is an alternative process (step).

<Step S52>
In the "upper limit accumulated time judgment" of step S52, it is judged whether or not the accumulated value of the accumulated excess time of step S51 satisfies "integrated value > out-of-step judgment accumulated value (upper limit side) H".
If "integrated value>H" (Yes), the process returns to step S23.
That is, it is determined that the value of ΔVmax (FIGS. 3A, 3B, 4A, and 4B) has increased due to the increase in the received voltage of the AC power supply 201, and the DC voltage value reference (ΔVtyp) is re-detected. Then, the process returns to step S23 to reset the determination value, and the steps after step S23 are performed again.
If "integrated value<H" (No), the process proceeds to step S35. Descriptions of steps S35 to S38 are omitted because they are redundant as described above.

<Step S53>
In the "excess time integration" of step S53 in FIG. 7, the voltage Vdet of the detected voltage waveform when the lower limit voltage determination is No in the lower limit voltage determination (S35) is corrected by the determination voltage threshold correction (S24). Accumulate the excess time exceeding the judgment voltage (lower limit side) Ds.
The process of accumulating the excess time in step S53 in FIG. 7 corresponds to the process of counting the number of times in step S43 in FIG. 6, and is a process (step) that replaces it.
After completing the "excess time accumulation" in step S53, the process proceeds to step S54.

<Step S54>
In the "lower limit accumulated time judgment" of step S54, it is judged whether or not the accumulated value of the accumulated excess time of step S53 satisfies "integrated value > out-of-step judgment accumulated value (lower limit side) I".
If "integrated value>I" (Yes), the process returns to step S23.
That is, in the lower limit side integrated time determination (S54), the integrated value obtained by integrating the time during which the voltage Vdet of the detected voltage waveform exceeds the determination voltage (lower limit side) Ds in the excess time integration (S53) is "integrated value>I". In the case of , it is determined that the value of Δmin has decreased due to the decrease in the receiving voltage, the DC voltage value reference (ΔVtyp) is re-detected, and the determination value is reset.
If "integrated value<I" (No), it is determined that the voltage received from the AC power supply 201 is within an appropriate range, and the determination operation of the flowchart is once terminated (End). Then, in the next out-of-step determination cycle, the operation of determining normality or out-of-step is performed again.

<Effects of the third embodiment>
In the third embodiment, in place of the number count S41, the upper limit excess number determination S42, the number count S43, and the lower limit excess number determination S44 of the second embodiment, out-of-step determination accumulated time (accumulated excess time) S51, It is replaced with the upper limit side accumulated time determination S52, the out-of-step detection accumulated time (exceeding time accumulation) S53, and the lower limit side accumulated time determination S54.
Therefore, depending on the features and characteristics of the adopted circuit configuration, there is an effect that the accuracy of out-of-step determination may be improved.

<<Fourth Embodiment / Power Conversion Device>>
The power converter according to the fourth embodiment of the present invention is a method focusing on ΔVmax, which is the maximum value (max) of the detected voltage (output voltage) of the DC voltage detector 15 (FIG. 2). Step-out determination according to the fourth embodiment will be described with reference to FIGS. 8A, 8B, 9A, 9B, and 10. FIG.
First, normal voltage waveforms and out-of-step voltage waveforms in the DC voltage detection unit 15 will be described with reference to FIGS. 8A, 8B, 9A, and 9B, respectively. Focusing on this ΔVmax, a flowchart for detecting out-of-step will be described with reference to FIG.

《Voltage waveform of the DC voltage detector when the rotating machine is operating normally》
8A and 8B show the DC voltage when the rotating machine 202 (M: FIG. 1) is operating normally under the rated load in the DC voltage detection unit 15 (FIG. 2) according to the fourth embodiment of the present invention. FIG. 8 is a diagram showing a voltage waveform example of a voltage Vdet (2005: FIG. 2, 3001: FIGS. 8A and 8B) that is the output voltage of the voltage detection unit 15;
8A and 8B, the horizontal axis is time [t] and the vertical axis is voltage [Vdc].
The voltage waveform indicated by characteristic line 3001 in FIGS. 8A and 8B is the voltage waveform across capacitor 152 (FIG. 2). A characteristic line 3011 indicates ΔVmax, which is the maximum value (max) of the voltage waveform (3001).

FIG. 8B is an enlarged view of the ripple component portion of the voltage waveform (3001) in FIG. 8A. FIG. 8B also shows the determination value C (3021), which is the out-of-step determination voltage (upper limit side), and the determination value D (3022), which is the out-of-step determination voltage (lower limit side).
Note that the characteristic line 3002 and the section Tc of the ripple component are omitted because they overlap with the explanations in FIGS. 3A and 3B.

FIGS. 8A and 8B above are rewritten focusing mainly on ΔVmax in FIGS. 3A and 3B, respectively.

《Voltage waveform of the DC voltage detector when the rotating machine is out of step》
9A and 9B show the case where the rotating machine 202 (M: FIG. 1) is out of step at the rated load in the DC voltage detector 15 (FIG. 2) according to the fourth embodiment of the present invention. 2 is a diagram showing an example voltage waveform of a voltage Vdet (2005: FIG. 2, 4001: FIGS. 9A and 9B), which is the output voltage of the DC voltage detection unit 15 in .
9A and 9B, the horizontal axis is time [t] and the vertical axis is voltage [Vdc].
The voltage waveform indicated by characteristic line 4001 in FIGS. 9A and 9B is the voltage waveform across capacitor 152 . A characteristic line 4011 indicates ΔVmax, which is the maximum value (max) of the voltage waveform (4001).

FIG. 9B is an enlarged view of the ripple component portion of the voltage waveform (4001, Vdet) in FIG. 9A. FIG. 9B also shows the determination value C (4021) of the out-of-step determination voltage (upper limit side) and the determination value D (4022) of the out-of-step determination voltage (lower limit side).
Note that the description of the characteristic line 4002 and the section Tc of the ripple component will be omitted because they are the same as those in FIGS. 4A and 4B.
9A and 9B described above are re-described mainly focusing on ΔVmax in FIGS. 4A and 4B, respectively.

<Flow chart of step-out determination unit 143>
Next, the operation of the out-of-step determining unit 143 shown in FIG. 10 of the fourth embodiment will be described with a flowchart.
FIG. 10 is a diagram showing an example of a flowchart of internal processing of the step-out determining unit 143 in the power converter according to the fourth embodiment of the present invention.

In the flowchart of FIG. 10 (fourth embodiment), as steps of a method for preventing erroneous determination of step-out, DC voltage reference detection S232, determination voltage threshold correction S242, upper limit side voltage determination S64, and lower limit side voltage determination S65 are performed. , the DC voltage reference detection S23, the determination voltage threshold correction S241, the upper limit side voltage determination S34, and the lower limit side voltage determination S35 in the flowchart of FIG. 7 (third embodiment).
Details of these changes are described in each step.

As described above, ΔVtyp was calculated from ΔVmax and ΔVmin. Therefore, if ΔVmax is used instead of ΔVtyp, there is an effect of lightening the computation of the judgment processing.
Note that the flowchart of FIG. 10 (fourth embodiment) is substantially the same as the flowchart of FIG. 7 (third embodiment) except for the above-mentioned replaced steps, so redundant description will be omitted as appropriate.

<Steps S20 to S22>
Steps S20 to S22 in the flowchart of FIG. 10 are substantially the same as steps S20 to S22 of the flowchart of FIG. 7 shown in the third embodiment.

<Step S232>
In the flowchart of FIG. 10, there is a "DC voltage value reference detection (ΔVmax)" as step S232. This step S232 replaces the "DC voltage value reference detection (ΔVtyp)" of step S23 in the flowchart of FIG. Thus, step S232 in FIG. 10 roughly corresponds to step S23 in FIG. 7, and is a process (step) for DC voltage value reference detection.
However, in step S23 in FIG. 7, ΔVtyp is detected and set. On the other hand, step S232 in FIG. 10 is a step of detecting and setting ΔVmax.
In FIG. 7 (third embodiment), the DC voltage detection unit 15 (FIGS. 1 and 2) detects the DC voltage value based on ΔVtyp as a reference value. Mode) is designed to detect ΔVmax as a reference value as a DC voltage value reference detection.

<Step S242>
Step S242 in FIG. 10 generally corresponds to step S241 in FIG. 7, and is a process (step) for correcting the determination voltage threshold.
However, in step S242 in FIG. 10, the step-out determination unit 143 corrects and sets the determination value Cs2, which is the out-of-step determination voltage (upper limit) used for out-of-step determination. In addition, it is corrected and set to a determination value Ds2, which is the out-of-step determination voltage (lower limit).
The change in the determination values (Cs2, Ds2) is due to the change in the reference value for DC voltage reference detection from ΔVtyp to ΔVmax. A specific correction method for correcting the determination value C to the determination value Cs2 and correcting the determination value D to the determination value Ds2 is set in advance in consideration of various factors.
Then, the process proceeds to step S64.

<Step S64>
In the flowchart of FIG. 10 (fourth embodiment), as step S64, the upper limit side voltage determination S64 determines "Vdet<Cs2" with respect to the voltage Vdet of the detected voltage waveform.
In the flowchart of FIG. 7 (third embodiment), the upper limit side voltage determination S34 as step S34 determines "Vdet<Cs" with respect to the voltage Vdet of the detected voltage waveform.
In other words, the determination of the upper limit side voltage, which was based on ΔVtyp in FIG. 7 (third embodiment), is performed based on ΔVmax in FIG. 10 (fourth embodiment).

<Step S65>
In the flowchart of FIG. 10 (fourth embodiment), the lower limit side voltage determination S65 as step S65 determines "Vdet<Ds2)" with respect to the voltage Vdet of the detected voltage waveform.
In the flowchart of FIG. 7 (third embodiment), the lower limit side voltage determination S35 as step S35 determines "Vdet<Ds" with respect to the voltage Vdet of the detected voltage waveform.
That is, in the lower limit side voltage determination, what was based on ΔVtyp in FIG. 7 (third embodiment) is performed based on ΔVmax in FIG. 10 (fourth embodiment).

<Steps S36 to S38>
In the flowchart of FIG. 10, steps S36 to S38 are substantially the same as steps S36 to S38 of the flowchart of FIG. 7 shown in the third embodiment. Redundant explanations are omitted.

<Steps S51 to S54>
In the flowchart of FIG. 10 (fourth embodiment), steps S51 to S54 are substantially the same as steps S51 to S54 of the flowchart of FIG. 7 shown in the third embodiment. Redundant explanations are omitted.

<Effects of the Fourth Embodiment>
While ΔVtyp is used in the third embodiment shown in FIG. 7, ΔVmax is used in the fourth embodiment shown in FIG.
As described above, ΔVtyp was calculated from ΔVmax and ΔVmin. Therefore, if ΔVmax is used instead of ΔVtyp, the fourth embodiment has the effect of lightening the computation of the determination process.

<<Other Embodiments>>
It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. In addition, part of the configuration of one embodiment can be replaced with part of the configuration of another embodiment, and further, part or all of the configuration of another embodiment can be added to the configuration of one embodiment. It is also possible to delete and replace.
Other embodiments and modifications will be further described below.

<<Combination of components of each embodiment>>
Although different constituent elements have been described for the first to fourth embodiments, these elements may be combined.
For example, in the fourth embodiment shown in FIG. 10, the DC voltage value reference detection in step S232 is set to ΔVmax, and the upper limit accumulated time determination in step S52 and the lower accumulated time determination in step S54 are combined. However, the method of setting the DC voltage value reference detection to ΔVmax is not limited to the fourth embodiment shown in FIG.
There is also a method of combining the DC voltage reference detection method using ΔVmax with the determination of the number of times of exceeding the upper limit side in step S42 and the determination of the number of times of exceeding the lower limit side in step S44 of the second embodiment shown in FIG.

《Reading out of step detection voltage》
In reading the set value in step S20 in FIG. 10 of the fourth embodiment, similarly to step S20 in FIG. loading. However, as the determination voltage threshold correction in step S241 of the third embodiment, the determination value Cs and the determination value Ds are corrected, respectively. The judgment value Cs2 and the judgment value Ds2 are corrected.
This difference in correction method is due to the fact that the DC voltage value reference detection of the third embodiment is based on ΔVtyp, while the DC voltage value reference detection of the fourth embodiment is based on ΔVmax.

Therefore, if the DC voltage value reference detection of the fourth embodiment is based on ΔVmax, the out-of-step determination voltage (upper limit side, lower limit side) is set to They are not limited to the judgment value C and the judgment value D, respectively.
Assuming that the DC voltage value reference detection is ΔVmax, a method of reading out of step determination voltages (upper limit side, lower limit side) suitable for it may be used.

《Step out detection》
In the voltage determination in step S25 in FIG. 5 and the upper limit side voltage determination and lower limit side voltage determination in step S34 in FIGS.
However, there are various methods of determination.
For example, after starting measurement, there is a method of sampling a plurality of cycles (Tc or more) to confirm a stable state, and then detecting or judging loss of synchronism. This method is, for example, to avoid current fluctuations due to other loads near where the voltage converter is installed.

《Memory part》
In the explanation of FIG. It has been described that the set conditions 2004 such as time are stored.
However, it is not limited to this method. For example, setting conditions 2004 such as a determination speed command, a determination pressure command, a step-out determination voltage, and a step-out determination time are written in a non-volatile memory such as a flash memory outside the power conversion device 1, and the setting conditions 2004 are written. A method of inserting a nonvolatile memory in which is written into the power converter 1 may be used.

《Setting values for loss of synchronism judgment processing》
The above <<storage unit>> has been described from the viewpoint of the storage unit 142 . Further, from the viewpoint of the set value group 2003 for out-of-step determination processing, although there is some overlap, it is as follows.
Judgment speed command A, judgment pressure command B, out-of-step judgment voltage (upper limit side) C (judgment value C), and out-of-step judgment voltage (lower limit side) D of the out-of-step detection processing set value group in the first to fourth embodiments (determination value D), out-of-step detection time E, out-of-step detection count (upper limit) F, out-of-step detection count (lower limit) G are written from the setting input unit 141 in FIG. 142 to the out-of-step determination unit 143 , but not limited to the setting input unit 141 .
It suffices if the storage unit 142 has information on the set values of the set value group for the out-of-step detection process. For example, the storage unit 142 may be a non-volatile memory, the set value group for out-of-step determination processing may be stored in the non-volatile memory, and the non-volatile memory may be replaced.

《Generation of speed command from pressure command》
The speed command unit 146 in the first embodiment uses proportional control (P control) or integral control (I control) when generating the speed command 2002 based on the pressure command 2001 of the pressure command unit 214. did. However, it is not limited to proportional control (P control) or integral control (I control), and proportional integral control (PI control) or PID control to which derivative control (D control) is added may be used.

"rectifier"
The rectifier 11 forms a three-phase diode bridge, but the constituent elements are not limited to diodes.
Instead of diodes, for example, switching elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) may be used to integrally control the gates of a plurality of MOSFETs for rectification.

《DC Voltage Detector》
In FIG. 2, the DC voltage detection unit 15 has been described with a configuration example of the voltage dividing resistor 151 and the capacitor 152, which are composed of three resistance elements 151A, 151B, and 151C.
However, the number of resistive elements is not limited to three. The voltage dividing resistor 151 may be composed of two, or four or more resistors.
Also, the number of capacitors 152 is not limited to one. For example, a capacitor with a large capacity (electrostatic capacity), which is difficult to cope with high frequencies, and a capacitor with a small capacity (capacitance), but with high frequency response, may be used in parallel.

<Other supplementary matters>
Although not a constituent element of the present invention, related matters will be additionally described below.

《Fluid machinery》
In FIG. 1, the fluid machine 203 is exemplified by a pump and a compressor, but is not limited to these. For example, in applications such as fans (gas) and screws (liquid), it is effective to use the power converter of the present invention to apply step-out determination of the rotating machine 202 that drives the fluid machine 203 .

《Fluid machine host device》
In the first embodiment shown in FIG. 1, the pressure detection unit 213 has been described as a device independent of the fluid machinery host device 204, but it is not limited to this. There is also a method in which the fluid machinery host device 204 is provided with the pressure detection unit 213 .
Further, when the fluid machine host device 204 is provided with the pressure detection unit 213, the pressure detection unit 213 and the pressure command unit 214 may be combined. That is, there is also a configuration in which the fluid machine host device 204 detects the pressure of the fluid machine 203 and immediately outputs the pressure command 2001 .

Reference Signs List 1 power conversion device 11 rectifier 12 smoothing capacitor 13 inverter section (inverter circuit, DC/AC converter)
14 inverter control unit 15 DC voltage detection unit 141 setting input unit 142 storage unit 143 step-out determination unit 144 cutoff unit 145 PWM control unit 146 speed command unit 151 voltage dividing resistor 151A, 151B, 151C resistance element 152 capacitor 201 AC power supply 202 Rotating machine (motor M)
203 Fluid machinery (pumps, compressors)
204 Fluid machinery host device 213 Pressure detector 214 Pressure command unit

Claims (15)

a rectifier that converts the AC voltage of the AC power supply to a DC voltage;
a smoothing capacitor for smoothing the DC voltage rectified by the rectifier;
an inverter unit that converts the DC voltage across the smoothing capacitor into an AC voltage;
an inverter control unit that controls the inverter unit;
with
The inverter control unit
a PWM control unit that controls the switching operation of the inverter unit;
a speed command unit for generating a speed command based on a pressure command requested by a fluid machine host device of a fluid machine connected to a rotating machine driven by the output of the inverter;
a step-out determination unit that determines step-out of the rotating machine based on the DC voltage detection value of the voltage of the smoothing capacitor, the pressure command, and the speed command;
and
The PWM control signal of the PWM control unit is blocked by the step-out determination of the step-out determination unit;
A power conversion device characterized by: In claim 1,
wherein the speed command unit performs proportional control or integral control when generating the speed command based on the pressure command;
A power conversion device characterized by: In claim 1,
A DC voltage detection unit that detects the DC voltage of the smoothing capacitor,
The DC voltage detection unit includes a voltage dividing resistor having a plurality of resistance elements, and a capacitor connected in parallel to the resistance elements.
A power conversion device characterized by: In claim 1,
The inverter control part is
a storage unit for storing a determination speed command, determination pressure command, out-of-step determination voltage, and out-of-step determination time of a group of out-of-step determination process setting values set from the outside;
The out-of-step determination unit performs out-of-step determination by referring to the setting values of the out-of-step determination process set value group stored in the storage unit.
A power conversion device characterized by: In claim 4,
The storage unit stores the number of out-of-step determinations in the out-of-step determination process set value group,
The out-of-step determination unit refers to the number of out-of-step determinations stored in the storage unit, and performs out-of-step determination.
A power conversion device characterized by: In claim 4,
The storage unit stores the out-of-step determination integrated value of the out-of-step determination process set value group,
The out-of-step determination unit refers to the out-of-step determination integrated value stored in the storage unit, and performs out-of-step determination.
A power conversion device characterized by: In any one of claims 4 to 6,
The inverter control unit has a setting input unit,
setting the out-of-step determination processing setting value group in the storage unit via the setting input unit;
A power conversion device characterized by: In any one of claims 4 to 6,
The storage unit is composed of a non-volatile memory, stores the set value group for out-of-step determination processing outside the power conversion device, and is provided in the inverter control unit.
A power conversion device characterized by: In any one of claims 4 to 6,
The out-of-step determination unit is configured to detect a step-out determination voltage set in the storage unit when the speed command and the pressure command exceed the determination speed command and the determination pressure command set in the storage unit, respectively. and step-out detection time,
A power conversion device characterized by: In any one of claims 4 to 6,
The power converter, wherein the out-of-step determination unit corrects the out-of-step determination voltage in the set value group for out-of-step determination processing according to fluctuations in the received power voltage. In claim 1,
The inverter unit outputs a three-phase AC voltage,
A power conversion device characterized by: In claim 1,
The inverter control unit is implemented by processing inside a microcomputer,
A power conversion device characterized by: A speed command unit provided in a power conversion device generates a speed command based on a pressure command requested by a fluid machine host device of a fluid machine connected to a rotating machine driven by the power conversion device,
A storage unit provided in the power converter stores various determination conditions such as a determination speed command, a determination pressure command, a step-out determination voltage, and a step-out determination time of a group of out-of-step determination process setting values set by the setting input unit. death,
A step-out determination unit provided in the power conversion device includes a DC voltage detection value of a voltage of a smoothing capacitor of the power conversion device, the various determination conditions stored in the storage unit, the pressure command, and the speed command. and to determine out-of-step of the rotating machine,
A step-out determination method for a power converter, characterized by: In claim 13,
A PWM control signal of a PWM control unit provided in the power converter for controlling the rotation of the rotating machine is blocked by the step-out determination by the step-out determination unit.
A step-out determination method for a power converter, characterized by: In claim 13 or claim 14,
wherein the speed command unit performs proportional control or integral control when generating the speed command based on the pressure command;
A step-out determination method for a power converter, characterized by:

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