RU2667477C1 - Device for controlling synchronization of power converter - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to the field of electrical engineering and can be used to drive an electric motor from a commercial power source. In the device for controlling the synchronization of the power converter, synchronization control section (3) controls the operation of the power converter (INV) in the V/f control mode by setting the first switch "on/off" (S1) to the open state, and the second switch "on/off" (S2) to the closed state. Control section (4) based on the synchronous current of the commercial power source controls the operation of the power converter (INV) in the V/f control mode by setting the first switch (S1) "on/off", and second switch (S2) is "on/off" in the closed state until the angular velocity of the engine M reaches a predetermined value, and changes the control of the power converter to current control based on the current measured by current sensor (2), after the angular velocity of the M motor has reached a predetermined value. Thereafter, the electric power is supplied to the motor from both the power converter (INV) and commercial power source (1) by setting first switch (S1) "on/off" to the closed state, and then the electric power is supplied to the M motor from commercial power source (1) by setting second switch (S2) "on/off" to the open state. Thus, the power converter control device performs precise current control and reliably changes the drive mode from the drive from the power converter to the drive from a commercial power source.EFFECT: technical result is to improve the accuracy of current control and ensure stable performance when switching the drive power from the power converter to the drive power from a commercial power source.13 cl, 25 dwg

Description

Technical field

[0001] The present invention relates to a control technique for driving an electric motor (hereinafter referred to as a motor) from a commercial power source as part of a control method in which the engine is started using a power converter, the power converter and the commercial power source are synchronized, and the mode is switched engine control from the drive from the power converter to the drive from a commercial power source.

State of the art

[0002] In a system for driving an engine from a commercial power source or mains, the start operation is facilitated in a start mode with direct connection to the line (start at full voltage). In this case, however, the starting torque reaches 200% ~ 300% of the estimated or rated torque, and the starting current reaches 600% ~ 800% of the rated motor current. Therefore, the start operation in this mode requires high power commercial commercial power sufficient for the required starting current.

[0003] To reduce the power of a commercial power supply, there is a motor start mode using a power converter (hereinafter referred to as INV inverter) comprising a direct conversion section for converting AC (AC) to DC (dc) and an inverse conversion section for converting DC to AC and synchronizing the INV inverter output with a commercial power supply.

[0004] The INV inverter performs the function of controlling the output voltage or output current. Accordingly, a method using an INV inverter can reduce the starting current to a lower value that is lower than the current level of the starting method with a direct connection to the line, and therefore reduces the required power of a commercial power source.

[0005] In a motor start operation using an INV inverter, the system synchronizes the output frequency and output voltage of the INV inverter with the output frequency and output voltage of a commercial power source and switches the motor operation from a drive from an inverter, or a drive using an INV inverter, to a drive from a commercial source power, or drive using a commercial power source. This operation is illustrated in FIG. 1, which schematically shows a device for controlling the synchronization of a power converter.

[0006] During engine start-up, the system controls the INV inverter by turning off the on / off switch S1 (open / closed state) of the commercial power supply 1 and turning on the on / off switch 2 of the INV inverter, and thereby supplying electricity from the INV inverter into motor M. When power is supplied from the INV inverter, motor M increases its angular velocity.

[0007] Then, after the angular speed of the motor M reaches a predetermined value, the system supplies power from the commercial power source 1 to the motor M, including the on / off switch S1 of the commercial power source 1 and turning off the on / off switch S2 inverter INV.

[0008] When the output of the commercial power source 1 and the output of the inverter INV are not synchronized when switching from the inverter INV to the drive of the commercial inverter 1, the possibility of overcurrent and voltage and stop the inverter 1 with the failure of the switching means. Therefore, it is necessary to precisely synchronize the output voltage of the commercial power source 1 and the inverter output INV.

[0009] Documents 1 and 2 disclose a switching method, briefly explained below. This switching method includes a phase adjustment operation after the frequency of the output voltage of the INV inverter is synchronized with the frequency of the output voltage of the commercial power source 1, and an operation of switching the drive mode to the drive from the commercial power source 1 by superimposing the output voltage of the INV inverter and the output voltage of the commercial source 1 power supply, when after adjusting the phase it was decided that the output voltage of the INV inverter is synchronized with the output voltage of the commercial source nick 1 Power.

[0010] FIG. 16 shows a situation in which, at the stage of matching or matching, the frequency of the output voltage vector (phase) of the inverter INV is ahead of the output voltage vector of the commercial power source 1. The frequency can be varied to adjust the phase in various ways. In any case, some time is needed to adjust the phase.

[0011] However, when switching that is performed in the phase-locked state during the period of overlapping the output voltage of the INV inverter and the output voltage of the commercial power source 1, if there is a deviation from the actual phase due to the control error, the phase shift between the INV inverter output voltage phase and the phase the output voltage of the commercial power source 1 tends to exceed the allowable range and cause a cross current, which will be discussed below. Therefore, overcurrent and overvoltage can occur, which can lead to failure and shutdown of the INV converter.

[0012] Patent Document 1 provides an apparatus for solving this problem. However, this device from Patent Document 1 is not effective enough to prevent overcurrent because current control in the INV inverter is not performed directly during the switching operation.

[0013] Therefore, the object of the synchronization control device is to perform more accurate current control and provide stable performance when switching from a drive from a power converter to a drive from a commercial power source.

Related Documents

Patent documents

[0014]

Patent Document 1: JP 2006-149136 A

Patent Document 2: JP 2007-228738 A

SUMMARY OF THE INVENTION

[0015] According to one aspect of the present invention, developed in view of the above problems inherent in known technical solutions, the synchronization control device of a power converter for supplying electricity from a commercial power source to an engine comprises: a first on / off switch installed between the commercial power source and engine; a serial circuit that is connected in parallel with the first on / off switch and which includes a power converter, an AC reactor, and a second on / off switch; a synchronization control section for controlling the power converter from the moment the engine is started until the output voltage of the commercial power source and the output voltage of the power converter are synchronized with each other; and a control section based on the synchronous current of the commercial power source for controlling the power converter after establishing synchronization between the output voltage of the commercial power source and the output voltage of the power converter; wherein the power converter synchronization control device is configured to switch control from the first power converter control using the synchronization control section to the second power converter control using the control section based on the synchronous current of the commercial power source; wherein the synchronization control section controls the operation of the power converter in the V / f control mode by setting the first on / off switch to the open state and the second on / off switch to the closed state; the control section based on the synchronous current of the commercial power source controls the operation of the power converter in the V / f control mode by setting the first on / off switch to the open state and the second on / off switch to the closed state immediately after switching from the first control using the power converter synchronization control section to then change the control of the power converter to current control based on the measured current at the output of the power converter power indicator, and then supply electricity to the engine from both the power converter and the commercial power source by setting the first on / off switch to the closed state, and then provide power from the commercial power source to the engine by setting the second on switch on / off "to open state.

[0016] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of three-phase output currents of a power converter, into a measured current along the d axis and the measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; and; and a section for converting two phases into three phases for converting the command voltage along the d axis and the command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source.

[0017] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of three-phase output currents of a power converter, into a measured current along the d axis and the measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a section for converting two phases into three phases for converting a command voltage along the d axis and a command voltage along the q axis into three-phase command voltages in accordance with a phase information element of a commercial power source; and a current control section for outputting the three-phase command voltage in accordance with the deviation between the measured three-phase currents and the three-phase command currents.

[0018] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of three-phase output currents of a power converter, into a measured current along the d axis and the measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; an output voltage error compensation section for outputting the difference obtained by subtracting the product obtained by multiplying the inductance of the AC reactor, the angular frequency component and the measured current along the q axis, from the command voltage along the d axis as the final command voltage along the d axis, and for outputting the sum obtained by adding the product of the inductance of the AC reactor, the angular frequency component and the measured current along the d axis with the command voltage along the q axis as e of the final command voltage along the q axis, and a section for converting two phases into three phases, intended for converting the final command voltage along the d axis and the final command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source.

[0019] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of three-phase output currents of a power converter, into a measured current along the d axis and the measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; an output voltage error compensation section for outputting the difference obtained by subtracting the product obtained by multiplying the inductance of the alternating current reactor, the components of the angular frequency and command current along the q axis from the command voltage along the d axis, as the final command voltage along the d axis, and for outputting the sum obtained by adding the product of the inductance of the alternating current reactor, the components of the angular frequency and command current along the d axis with the command voltage along the q axis, as the final th voltage command along the q axis, and converting a section of two phases in three phases for converting final voltage command along the axis d and the final voltage command along the q-axis in the three-phase voltage command in accordance with the element information of the commercial power supply phase.

[0020] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of three-phase output currents of a power converter, into a measured current along the d axis and the measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; output voltage error compensation section, designed to calculate the voltage drop compensation value by multiplying the inductance of the AC reactor, the angular frequency component and current in the drive load during synchronization based on a commercial source with the calculation θcomp = tan ^-1 (command current along the d axis / command current along the q axis) in accordance with the command current along the d axis and the command current along the q axis, to calculate the voltage drop compensation component along the d axis by multiplying the compensation value and voltage drop and sin (θcomp), to calculate the voltage drop compensation component along the q axis by multiplying the voltage drop compensation value and cos (θcomp) with the derivation of the difference obtained by subtracting the voltage drop compensation component along the d axis from the command voltage along the d axis, as the final command voltage along the d axis, and outputting the sum obtained by adding the voltage drop compensation component along the q axis and the command voltage along the q axis, as the final command voltage along the q axis; and a section for converting two phases into three phases for converting the final command voltage along the d axis and the final command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source; wherein at least one of the current in the drive load during synchronization based on a commercial power source and the angular frequency component is a constant value.

[0021] According to another aspect of the present invention, the output voltage error compensation section sets the current along the q axis or the command current along the q axis to zero if the absolute value of the current along the q axis and the command current along the q axis is less than or equal to a predetermined value.

[0022] According to another aspect of the present invention, the device for controlling the synchronization of the power converter further comprises a transition switch for receiving a command voltage along the d axis, command voltage along the q axis, final command voltage along the d axis, and final command voltage along the q axis and for outputting the final command voltage along the d axis and the final command voltage along the q axis to the section for converting two phases into three phases during the V / f control mode, and command voltage along the d axis and command voltage along the q axis into the section for converting two phases into three phases during current control.

[0023] According to another aspect of the present invention, a synchronous current control section of a commercial power supply comprises: a low-pass filter for removing a high-frequency component (s) in the measured current along the d axis and the measured current along the q axis and for supplying the measured current along the d axis and the measured current along the q axis to the junction switch.

[0024] According to another aspect of the present invention, a synchronous current control section of a commercial power supply reduces the command current along the d axis and the command current along the q axis after a predetermined time period from switching to current control.

[0025] According to another aspect of the present invention, a synchronous current control section of a commercial power supply reduces the command current along the q axis to zero, and then reduces the command current along the d axis to zero.

[0026] According to another aspect of the present invention, the synchronous current control section of the commercial power source changes the phase information element of the commercial power source smoothly from the output phase of the power converter to the output voltage phase of the commercial power source when there is an error or difference between the phase of the output voltage of the power converter and the phase of the output voltage of a commercial power source.

[0027] According to another aspect of the present invention, the two-phase to three-phase converting section converts the command voltage along the d axis and the command voltage along the q axis to three-phase command voltages in accordance with the phase of the output voltage of the power converter during the V / f control mode, and converts the command voltage along the d axis and the command voltage along the q axis to three-phase command voltages in accordance with the phase information element of the commercial power source during current control, and the section converting the three phases into two phases converts the three-phase measured currents to the measured current along the d axis and the measured current along the q axis in accordance with the phase of the output voltage of the power converter during the V / f control mode, and converts the three-phase measured currents to the measured current along the d axis and the measured current along the q axis in accordance with the phase information element of the commercial power source during current control.

[0028] According to the present invention, in the synchronization control device for the inverter, it is possible to perform current control more accurately and switch operation from the drive from the power converter to the drive from a commercial power source with greater stability.

Brief Description of the Drawings

[0029] FIG. 1 schematically shows a power converter synchronization control device according to a first embodiment of the present invention.

In FIG. 2 is a timing chart illustrating timing control operations according to a first embodiment of the present invention.

In FIG. 3 is a block diagram of a synchronous current control section of a commercial power supply according to a first embodiment of the present invention.

In FIG. 4 is a block diagram of a synchronous current control section of a commercial power supply according to a second embodiment of the present invention.

In FIG. 5 is a block diagram of a synchronous current control section of a commercial power supply according to a third embodiment of the present invention.

In FIG. 6 is a flowchart of a reduction process section according to a third embodiment of the present invention.

In FIG. 7 is a timing chart illustrating timing control operations according to a third embodiment of the present invention.

In FIG. 8 is a flowchart of a reduction process section according to a fourth embodiment of the present invention.

In FIG. 9 is a block diagram of a synchronous current control section of a commercial power supply according to a fifth embodiment of the present invention.

In FIG. 10 is a block diagram showing a rate of change limiting section according to a fifth embodiment of the present invention.

In FIG. 11 shows the coordinates of α-β and the coordinates of d-q.

In FIG. 12 shows the coordinates rotating synchronously with the frequency of the primary motor winding and the phase of the commercial power source.

In FIG. 13 schematically shows a synchronous current control section of a commercial power supply according to a sixth embodiment of the present invention.

In FIG. 14 is a block diagram showing a coordinate axis selection section according to a sixth embodiment of the present invention.

In FIG. 15 schematically shows a synchronous current control section of a commercial power supply according to a seventh embodiment of the present invention.

In FIG. 16 shows the inverter output voltage vector, wherein the voltage vector of the commercial power source is plotted in the direction of the α axis.

In FIG. 17 is a vector diagram of an inverter output voltage.

In FIG. 18 is a block diagram showing a synchronous current control section of a commercial power supply according to an eighth embodiment of the present invention.

In FIG. 19 is a block diagram showing an output voltage error compensation section along the d axis according to an eighth embodiment of the present invention.

In FIG. 20 is a block diagram showing an output voltage error compensation section along the q axis according to an eighth embodiment of the present invention.

In FIG. 21 is a block diagram showing an output voltage error compensation section along the q axis according to a ninth embodiment of the present invention.

In FIG. 22 is a block diagram showing a synchronous current control section of a commercial power supply according to a tenth embodiment of the present invention.

In FIG. 23 is a block diagram showing an output voltage error compensation section according to an eleventh embodiment of the present invention.

In FIG. 24 is a vector diagram illustrating currents along the d axis and along the q axis and voltage drop across an AC reactor.

In FIG. 25 is a block diagram showing a portion of a synchronous current control section of a commercial power supply according to a twelfth embodiment of the present invention.

Methods for implementing the present invention

[0030] The synchronization control device of the power converter according to the present invention is described in detail below with reference to embodiments 1-12 thereof as shown in FIG. 1-25.

[0031] [Embodiment 1 of the present invention]

In FIG. 1 schematically shows a power converter synchronization control device according to a first embodiment of the present invention. A commercial power supply 1 or a mains network is a three-phase AC source. An on / off switch S1 (or open / closed) for connecting a commercial power source 1 is installed between the commercial power source 1 and the motor M. The serial circuit runs parallel to the on / off switch S1. This series circuit is a series combination of an input transformer T2, an INV inverter, an AC reactor L, and an on / off switch (or open / closed) S2 for the INV inverter. On the output side of the INV inverter, there is a current sensor 2 for receiving a three-phase measured current value Iu, Iv, and Iw of the INV inverter. The on / off switches S1 and S2 are turned on or off to change the motor power between the drive from a commercial power source, i.e. driven by a commercial power source 1, and driven by an inverter, i.e. driven by INV inverter.

[0032] The AC reactor L is designed to reduce current due to potential difference and phase shift between the output voltage of the commercial power source 1 and the output voltage of the inverter INV during switching between the drive from the inverter INV and the drive from the commercial power source 1.

[0033] A synchronization transformer T1 with a commercial power source is installed so that it measures the output voltage of a commercial power source 1. When using information about the commercial power source 1 (amplitude, phase, frequency, etc. of the output voltage of the commercial power source 1) measured by the synchronization transformer T1 with the commercial power source, the synchronization control section 3 and the control section 4 based on the synchronous current of the commercial source The power supply controls the synchronization of the INV inverter. The switch S3 switches in accordance with the synchronization completion flag issued by the synchronization control section 3. Until the synchronization completion flag is set (during the time from the moment the engine starts to synchronization between the output voltage of the commercial power supply 1 and the output voltage of the power converter), the switch S3 is in the off state, and therefore, the synchronization control section 3 controls the INV inverter. After the synchronization completion flag is set (after synchronization is established between the output voltage of the commercial power supply 1 and the output voltage of the power converter), the switch S3 is on and therefore, the control section 4 based on the synchronous current of the commercial power supply controls the inverter INV.

[0034] Hereinafter, the current generated by the potential difference and the phase shift between the output voltage of the commercial power source 1 and the output voltage of the inverter INV is called the cross current. In FIG. 2 illustrates current synchronization control of a commercial power supply. The sync completion flag is set at the time of “sync completion” shown in FIG. 2.

[0035] FIG. 3 shows a block diagram of a control section 4 based on the synchronous current of a commercial power supply. As shown in FIG. 3, the control section 4 based on the synchronous current of the commercial power supply comprises a first buffer Z ^-1 , a phase calculation section 5 of the commercial power supply, a three phase to two phase conversion section 7, a second buffer Z ^-1 , a switch switch S4, a current control section 6 and section 8 converting two phases into three phases. The first buffer Z ^-1 gives the previous values for one sample of the previous three-phase measured currents Iu, Iv, Iw. Thus, the previous values of the three-phase measured currents Iu, Iv, Iw are the values obtained directly in the previous sample. The phase calculation section 5 of the commercial power source calculates the phase θ _s or the phase information element θ _s of the output voltage phase of the commercial power source 1. According to the phase information element θ _s of the output voltage of the commercial power source 1, the three-phase to two-phase converter section 7 converts the previous values of the three-phase measured currents, Iu, Iv and Iw, obtained in the previous sample, into the measured current I _d along the d axis and the measured current I _q along the axis q. The second buffer Z ^-1 gives the previous values of the command current Id * along the d axis and the command current Iq * along the q axis obtained in the previous sample. According to the current control switching flag, the transition switch S4 outputs the measured current Id along the d axis and the measured current Iq along the q axis as the command current Id * along the d axis and the command current Iq * along the q axis during V / f control, and displays the previous values of the command current Id * along the d axis and the command current Iq * along the q axis (outputs of the second buffer Z ^-1 ) as the command current Id * along the d axis and command current Iq * along the q axis during current control. The current control section 6 provides the command voltage Vd * along the d axis and the command voltage Vq * along the q axis in accordance with the deviation between the measured current Id along the d axis and the command current Id * along the d axis and the deviation between the measured current Iq along the q axis and the command current Iq * along the q axis. According to the phase information element θ _s of the commercial power source 1, the two-phase to three-phase conversion section 8 converts the command voltage Vd * along the d axis and the command voltage Vq * along the q axis into three-phase command voltages Vu *, Vv * and Vw *. The INV inverter is controlled by three-phase command voltages Vu *, Vv * and Vw * generated by the conversion section 8 of the two phases into three phases. In the example of FIG. 2, the current switching flag is on or set to on. at the moment of one cycle of the inverter output voltage after the moment of selecting “sync completion”. The moment of turning on the current control switching flag is not limited to the moment shown in the example of FIG. 2.

[0036] As the command values, the current control section 6 uses the values of the measured current Id along the d axis and the measured current Iq along the q axis just before switching from the V / f control (control, which seeks to make the output voltage / output frequency of the INV inverter constant) to current control (ACR control in FIG. 2). Therefore, until the current control switching flag is set, current control commands are determined by continuing to update the measured current Id along the d axis and the measured current Iq along the q axis. After the current control switching flag is turned on, the previous values of the command current Id * along the d axis and the command current Iq * along the q axis (that is, the measured current Id along the d axis and the measured current Iq along the q axis immediately before the current switching control flag is turned on) remain unchanged continuously.

[0037] The three-phase command voltages Vu *, Vv * and Vw * of the INV inverter at the time of synchronization completion are equal to the values obtained by adjusting the voltage amplitude and phase of the commercial power supply 1, and therefore are given by the following expression (1).

[0038]

[0039] In this mathematical expression, V is the effective voltage value, θ is the phase of the output voltage of the INV inverter, and V is set equal to the effective value of the output voltage of the commercial power source 1. In this case, the three-phase measured currents Iu, Iv and Iw flowing through the motor M are defined as the following mathematical expressions (2).

[0040]

[0041] In this expression, I is the effective value of the measured current.

[0042] In this case, the three-phase to two-phase conversion section 7 performs the coordinate conversion of the three-phase measured currents Iu, Iv and Iw to the measured current Id along the d axis and the measured current Iq along the q axis using the coordinate transformation formula defined by the mathematical expression (3 ) The phase θs of the commercial power source 1 is used as an element of the phase information necessary for coordinate conversion.

[0043]

[0044] In this expression, θs is a phase information element of a commercial power source 1.

[0045] The measured current Id along the d axis and the measured current Iq along the q axis are given by the following expression (4).

[0046]

[0047] When switching from the drive from the INV inverter to the drive from the commercial power source 1, the synchronization between the output voltage of the INV inverter and the output voltage of the commercial power source 1 is completed. Therefore, the difference between the phase of the output voltage of the commercial power source 1 and the phase of the output voltage of the INV inverter is negligible, and therefore the assumption that they are equal to each other has almost no effect on the control.

[0048] Accordingly, it is assumed that θ = θs. In this case, the measured current Id along the d axis and the measured current Iq along the q axis are given by the following expression (5).

[0049]

[0050] The current control section 6 generates a command voltage Vd * along the d axis and a command voltage Vq * along the q axis, performing proportional and integral control (PI control) based on the difference between the command current Id * along the d axis and the measured current Id along the axis d and the difference between the command current Iq * along the q axis and the measured current Iq along the q axis. When Id = √3I and Iq = 0 are applied to the inputs of the current control section 6, as in expression (5), the command voltage Vd * along the d axis and the command voltage Vq * along the q axis generated by the current control section 6 are determined by the following expression ( 6).

[0051]

[0052] Then, the two-phase to three-phase conversion section 8 converts the command voltage Vd * along the d axis and the command voltage Vq * along the q axis into three-phase command voltages Vu *, Vv * and Vw * using the coordinate transformation formula given by the following expression ( 7), where θs is the phase of the commercial power source 1.

[0053]

[0054] In this case, the three-phase command voltages Vu *, Vv * and Vw * are given by the following expression (8).

[0055]

[INV] The INV inverter is controlled so that the output voltages of the INV inverter are equal to the command three-phase voltages Vu *, Vv *, and Vw *, respectively. In this example, the INV inverter generates output voltages by controlling the on / off switching of the switching device (s) in the inverter using the comparison signal (s) between the three-phase command voltages Vu *, Vv * and Vw * and the wave signal (s) in the configuration the triangle.

[0057] In this case, the output voltage of the inverter INV and the output voltage of the commercial power source 1 are almost synchronous with respect to each other in voltage amplitude and phase, as a result of which almost no cross current is generated.

[0058] As shown above, the timing control device for the power converter according to the first embodiment of the present invention provides reliable switching from a drive from an INV inverter to a drive from a commercial power supply 1. In addition, in the current control, in which the output current of the INV inverter is measured and the command current is supported, the synchronization control device according to the first embodiment of the present invention improves control accuracy and enhances the cross-current limitation in comparison with Patent Document 1.

[0059] Therefore, when switching from a drive from a power converter to a drive from a commercial power source, the power converter can operate stably without failures and stops due to overcurrent or voltage. Accordingly, the reliability of the engine drive system is increased.

[0060] [Embodiment 2 of the present invention]

In a second embodiment of the present invention, a low pass filter (LPF) is added to the synchronous current control section 4 of the commercial power supply from the first embodiment of the present invention.

[0061] FIG. 4 is a block diagram of a synchronous current control section 4 of a commercial power supply according to a second embodiment of the present invention.

[0062] As shown in FIG. 4, in a second embodiment of the present invention, a low-pass filter LPF is installed between the three-phase to two-phase conversion section 7 and the transition switch S4. The measured current Id along the d axis and the measured current Iq along the q axis can include a bias component due to the residual magnetic flux of the HCT [Hall sensor] used as the current sensor, and current errors of the current sensor 2, and the 1st and 2nd harmonic components of the output frequency generated due to a gain shift in sensitivity. In addition, the noise applied to the current sensor 2 is also superimposed on the measured current Id along the d axis and the measured current Iq along the q axis.

[0063] If this interference occurs, the measured current Id along the d axis and the measured current Iq along the q axis deviate from the correct values, which should be used as the command current Id * along the d axis and the command current Iq * along the q axis. Accordingly, in the case of current control, the INV inverter may not be able to generate a current exceeding the load torque, and the motor M may stop.

[0064] The low-pass filter LPF has the function of preventing the passage of high-frequency components in the measured current Id along the d axis and the measured current Iq along the q axis. Therefore, the LPF low-pass filter eliminates the above interference, which exists in the form of a high-frequency component.

[0065] As stated above, the second embodiment of the present invention provides the same operations and effects as the first embodiment of the present invention. In addition, the second embodiment of the present invention eliminates the interference, even if due to the presence of a shift component due to residual magnetic flux in the current sensor 2, an error occurs in the circuit and the 1st and 2nd harmonic components of the output frequency due to this shift of the measured gain.

[0066] [Embodiment 3 of the present invention]

In FIG. 5 is a block diagram of a current synchronization control section 4 of a commercial power supply according to a third embodiment of the present invention. In a third embodiment of the present invention, as shown in FIG. 5, between the transition switch S4 and the current control section 6, a reduction process section 9 is set. After the output voltage of the inverter INV and the output voltage of the commercial power supply 1 are superimposed, the on / off switch S2 shown in FIG. 1, open for inverter operation. In this case, if the current on the side of the commercial power source is almost equal to zero, and the current on the side of the inverter is almost equal to the motor current during the opening of the on / off switch S2, then the current on the side of the commercial power source instantly rises due to switching the power supply from the inverter to a commercial power source, and the switching operation may become unstable. Therefore, the reduction process section 9 gradually reduces the current on the inverter side while opening the on / off switch S2.

[0067] FIG. 6, a reduction process section 9 is shown in detail. Subtractor 21 subtracts the previous output value of the subtractor 25 described below, which is the output from the transition switch S4 in the previous sample. The switch 22 checks the polarity of the command current Id * along the d axis or the command current Iq * along the q axis in accordance with the flag of the polarity of the command current indicating the polarity of the command current Id * along the d axis or command current Iq * along the q axis and rotates the contact of the switch 22 to the positive side or the negative side in accordance with this polarity. When the command current Id * along the d axis or the command current Iq * along the q axis is positive, the reduction rate limiter 23a reduces the command current Id * along the d axis or the command current Iq * along the q axis with a decreasing rate from a positive value to zero. When the command current Id * along the d axis or the command current Iq * along the q axis is negative, the reduction rate limiter 23b reduces the command current Id * along the d axis or the command current Iq * along the q axis with a decreasing rate from negative to zero.

[0068] The switch 24 operates similarly to the switch 22. The subtractor 25 subtracts the value from the output of the switch 24 from the value from the output of the subtractor 25. The buffer 26 outputs the previous value from the subtractor 25, obtained one sample earlier.

[0069] The above command current polarity flag is set depending on the command current polarity before smoothing, as shown in FIG. 6. When the command current before smoothing is positive, the polarity flag of the command current is positive, and accordingly the switches 22 and 24 are turned on in the positive direction. When the command current is negative before smoothing, the polarity flag of the command current is negative, and accordingly, the switches 22 and 24 are turned on in the negative direction.

[0070] The reduction process section 9 constructed as shown in FIG. 6, there is both a command current Id * along the d axis and a command current Iq * along the q axis.

[0071] FIG. 7 is a timing chart illustrating timing control operations according to a third embodiment of the present invention. In this example, the speed reduction is not performed from the moment of switching to current control until the moment the inverter current decreases (INV CURRENT DECREASE START), which is the moment when a predetermined period of time elapses from switching to current control, as shown in FIG. 7. In addition, the on / off switch S1 of the commercial power supply 1 is turned on from the moment of switching to current control until the “inverter current decrease starts”.

[0072] A power converter synchronization control device according to a third embodiment of the present invention is capable of providing the same operations and effects as the first and second embodiments of the present invention. In addition, since the current on the inverter side during the opening of the on / off switch S2 for the INV inverter is almost zero, intermittent operation during switching from the drive from the INV inverter to the drive from the commercial power supply 1 can be prevented.

[0073] [Embodiment 4 of the present invention]

In a third embodiment of the present invention, the command current Id * along the d axis and the command current Iq * along the q axis were reduced simultaneously. In contrast, in the fourth embodiment of the present invention, the command current Iq * along the q axis is reduced to zero, and then the command current Id * along the d axis is reduced to zero.

[0074] The current Id along the d axis is the current controlling the magnetic flux. Without magnetic flux, motor M cannot generate torque and rotate. Therefore, the method of said reduction according to the fourth embodiment of the present invention can make the switching operation more stable.

[0075] FIG. 8 shows in detail a reduction process section 9 according to a fourth embodiment of the present invention. Section 41 checking zero command current is installed on the output side of section 9 of the reduction process on the side of the q axis. Section 41 checking the command current zero is used to determine whether or not the command current Iq * has decreased to zero along the q axis and issuing the command current zero flag along the q axis. In addition, the command current zero checking section 41 receives the signal from the output of the subtractor 25 and provides this signal from the output of the subtractor 25 directly as the command current along the q axis after smoothing. The above flag of the command current polarity is set depending on the polarity of the command current along the q axis before smoothing (Fig. 8), as in the third embodiment of the present invention.

[0076] On the d-axis side, there are switches 42 and 43 on the input side, and section 9 of the reduction process, respectively, on the output side. Each of the switches 42 and 43 on the input and output sides is configured to turn on when the command zero flag along the q axis is supplied from the side of the command zero checking section 41. When the command current Iq * along the q axis becomes zero, that is, Iq * = 0, the command current zero check section 41, shown at the bottom of FIG. 8 sets the zero flag of the command current, and therefore the switches 42 and 43 shown at the top of FIG. 8, go into the on state. (ON) (side facing section 9 of the reduction process).

In addition, a reduction process can be performed using a design that first reduces the current along the d axis and then reduces the current along the q axis.

[0077] As shown above, the fourth embodiment of the present invention can provide the same operations and effects as the first to third embodiments of the present invention. In addition, the fourth embodiment of the present invention can provide more stable operation of switching from a drive from an INV inverter to a drive from a commercial power supply 1 compared to the third embodiment of the present invention.

[0078] [Embodiment 5 of the present invention]

In FIG. 9 is a block diagram of a synchronous current control section 4 of a commercial power supply according to a fifth embodiment of the present invention.

[0079] The output voltage phase of the INV inverter is controlled by the output voltage phase of the commercial power source 1 after switching to current control. However, during V / f control, the phase of the output voltage of the INV inverter is controlled by the phase θ determined by calculating the frequency of the output of the INV inverter.

[0080] Therefore, there is a gap or deviation between the phase of the output voltage of the commercial power source 1 and the phase of the output voltage of the INV inverter during the period from the completion of synchronization to the beginning of current control (period from "synchronization completion" to "control switch" changeover) shown in Fig. 2 and Fig. 7). Due to this phase gap, the accuracy of the current control may decrease and cause overcurrent during the overlap period shown in FIG. 2 and FIG. 7.

[0081] Therefore, the synchronous current control section 4 of the commercial power supply according to the fifth embodiment of the present invention further comprises an output frequency calculation section 10 for calculating an output frequency of an INV inverter, a phase calculation section 11 for calculating an INV inverter output phase phase θ, and a section 12 rate limits for maintaining a gap or deviation between the phase of the output voltage θ1 of the commercial power supply 1 and the phase θ of the output voltage of the INV inverter during switching and gradual reduction of this gap to zero by introducing changes to the speed limit.

[0082] FIG. 10 shows in more detail section 12 limits the rate of change. The change rate limiting section 12 comprises a subtraction section 51, a switch 52, switches 53 and 56, a reduction rate limiter, an absolute value calculation section 55, a buffer Z ^-1 and a subtraction section 57. The subtraction section 51 calculates the difference (θ-θ1) between the output voltage phase θ1 of the commercial power source 1 and the inverter INV phase θ of the inverter INV calculated by the phase calculation section 11 of FIG. 9. The switch 52 outputs the difference between the phase θ1 of the output voltage of the commercial power source 1 and the phase θ of the output voltage of the INV inverter during the period when the synchronization completion flag is set to off, and outputs the previous value from the output of the switch 56 obtained one sample earlier during the period when the synchronization completion flag is set to on. Each of the switches 53 and 56 is turned to the positive side when the error polarity check flag is positive, and to the negative side when the error polarity check flag is negative. The reduction rate limiter comprises a positive side reduction rate limiter 54a for decreasing the positive values to zero and a negative decreasing rate limiter 54b for decreasing the negative values to zero from the negative side. The absolute value calculation section 55 calculates the absolute value at the output of the negative side rate limiter 54b. The buffer Z ^{-1 is} designed to output the previous value from the output of the switch 56, obtained one sample earlier. The subtraction section 57 subtracts the output value of the switch 56 from the phase information element θs of the phase information of the commercial power source 1.

[0083] From the moment the synchronization completion flag is turned on at the time of “sync completion”, the difference between the output voltage phase θ1 of the commercial power source 1 and the output voltage phase θ from the output of the phase computing section 11 decreases from the value immediately before this reduction rate limiter 54a, 54b. The polarity of the phase difference (θ-θ1) of the phases is estimated, and the phase error polarity flag is set positive if the phase difference is positive, and negative if the phase difference is negative. The decrease rate limiter 54a reduces the phase shift from a positive value to zero if the phase error polarity flag is set positive, and the decrease rate limiter 54b reduces the phase shift from a negative value to zero if the phase error polarity flag is set to negative. The absolute value calculation section 55 calculates the absolute value of the signal at the output of the reduction rate limiter 54b. When the phase shift decreases to zero either from the side of the positive values or from the side of the negative values, the limiter 54a or in 54b of the reduction rate outputs zero. The result obtained by subtracting the output signal for this process (switch output 56), as phase θ1 from the commercial power source 1, is output as the phase information element θs used in the three-phase to two-phase conversion section 7 and the two-phase conversion section 8 the three phases shown in FIG. 9.

[0084] Thus, when an error is generated between the output voltage phase θ of the INV inverter INV and the output voltage phase θ1 of the commercial power source 1, the system gradually changes the phase information element θs of the phase of the commercial power source 1 used in the three-phase to two-phase conversion section 7 and an element 8 for converting two phases into three phases from the phase θ of the output voltage of the inverter INV to the phase θ1 of the output voltage of the commercial power source 1.

[0085] No speed reduction is performed during the period before the completion of the sync completion shown in FIG. 2 and 7.

[0086] As stated above, the fifth embodiment of the present invention can provide the same operations and effects as the first to fourth embodiments of the present invention. In addition, the rate of change rate limiting section 12 can prevent a sharp change in current while the drive from the INV inverter and the drive from the commercial power supply 1 overlap with each other. Accordingly, a fifth embodiment of the present invention can prevent a failure and a stop and ensure stable operation.

[0087] [Embodiment 6 of the present invention]

In the first embodiment of the present invention and the fifth embodiment of the present invention, when moving from the coordinate system of the phase of the output frequency of the inverter INV to the coordinate system of the phase of the output voltage of the commercial power supply 1, only the phase is taken into account. In the sixth embodiment of the present invention, in contrast, the conversion from one coordinate system to another is performed taking into account the phase and magnitude of the voltage. In FIG. 11 shows the relationship between the voltage vector of a three-phase alternating current, the coordinate system α-β and the coordinate system d-q.

[0088] The α-β coordinate system is a coordinate system after converting from three phases to two phases, it is called a fixed coordinate system. The d-q coordinate system is a coordinate system that rotates in the α-β coordinate system at a certain speed. In the general case, this coordinate system is a coordinate system that rotates synchronously with the frequency of the primary winding of the motor M and is called the rotational coordinate system.

[0089] FIG. 12 shows a coordinate system dm-qm, which is defined as a coordinate system rotating synchronously with the frequency of the primary motor winding M, and a coordinate system ds-qs, which is defined as a coordinate system, rotating synchronously with the voltage phase of a commercial power source 1.

[0090] The phase of the frequency of the primary winding of the motor M is denoted by θm, and the phase information element representing the phase of the commercial power source 1 is denoted by θs. The voltage vector V1 is determined as shown in FIG. 12. In this case, the voltage vector V1 is distributed between the coordinate system dm-qm and the coordinate system ds-qs. In this case, the stress along the d axis of the coordinate system dm-qm is denoted by Vdm, and the stress along the q axis is denoted by Vqm. The stress along the d axis in the coordinate system ds-qs is denoted by Vds, and the stress along the q axis is denoted by Vqs.

[0091] In the phase change operation used to convert the coordinates from the frequency phase at the output of the INV inverter to the phase of the output voltage of the commercial power source 1 (at the time of “control changeover” in FIG. 2 and FIG. 7), it is possible to achieve changing the phase of the output voltage of the commercial power source 1 while maintaining the magnitude of the voltage vector in the primary winding of the motor M (voltage supplied to the motor M) by changing the voltage along the d axis from Vdm to Vds and changing the voltage along the q axis from Vqm to Vqs.

[0092] Through this operation, the system can make the voltage supplied to the motor M more stable during the switching operation.

[0093] FIG. 13 is a block diagram of a synchronous current control section 4 of a commercial power supply according to a sixth embodiment of the present invention. In the sixth embodiment of the present invention, there are sections 13 and 14 for selecting the coordinate axes instead of the section 7 for converting three phases into two phases and section 8 for converting two phases into three phases. The operations described above are performed in sections 13 and 14 of the selection of coordinate axes. In FIG. 14 shows in detail the block diagram of the coordinate axes 13 and 14. In FIG. 14, the coordinate axis selection section 14 comprises sections 31 and 32 for converting two phases into three phases, and the coordinate axis selection section 13 contains sections for converting three phases into two phases 34 and 35. For corresponding coordinate transformations, the two-phase to three-phase conversion section 32 and the three-phase to two-phase conversion section 35 use the phase information element θs of the commercial power source 1. For the respective coordinate transformations, the two-phase to three-phase conversion section 31 and the three-phase to two-phase conversion section 34 use the INV phase of the inverter output voltage INV. The current control switching flag is set at the time “control changeover” shown in FIG. 2 or FIG. 7.

[0094] Before switching to current control (ACR control), the transition switches 33 and 36 of FIG. 14 are set to the on position, and therefore coordinate conversions are performed in the two-phase to three-phase conversion section 31 and the three-phase to two-phase conversion section 34 using the phase θ of the INV inverter output command voltage. After switching to current control (ACR control), the transition switches 33 and 36 in FIG. 14 are set to the on position, and therefore coordinate conversions are performed in the two-phase-three-phase conversion section 32 and the three-phase-two-phase conversion section 35 using the phase information element θs of the phase information of the commercial power source 1.

[0095] Thus, a sixth embodiment of the present invention can provide the same operations and effects as the first to fifth embodiments of the present invention. In addition, you can maintain the magnitude of the voltage vector in the primary winding of the motor M unchanged and perform a phase change of the output voltage of the commercial power source 1 with a constant value of this vector.

[0096] [Embodiment 7 of the present invention]

In FIG. 15 shows a synchronous current control section of a commercial power supply according to a seventh embodiment of the present invention. Current control can be performed in the form of a three-phase current without performing coordinate conversion. In this case, as shown in FIG. 5, the command current Id * along the d axis and the command current Iq * along the q axis are converted into command three-phase currents Iu *, Iv * and Iw * using section 8 converting two phases into three phases. Then, the current control section 6 calculates the three-phase command voltages Vu *, Vv *, Vw * in accordance with the deviation between the three-phase command current Iu *, Iv *, Iw * and the three-phase measured current Iu, Iv, Iw.

[0097] A seventh embodiment of the present invention can provide the same operations and effects as the first to sixth embodiments of the present invention. In addition, you can omit the calculation of the coordinate transformation during current control and simplify the design of the current control system.

[0098] [Embodiment 8 of the present invention]

The output voltage of the INV inverter decreases due to a voltage drop due to the AC reactor L connected to the output of the INV inverter. This voltage drop across the AC reactor L causes a potential difference and a phase shift between the output voltage of the INV inverter and the voltage of the commercial power supply, and ultimately causes a cross current. An eighth embodiment of the present invention compensates for this voltage drop caused by the AC reactor L to prevent the occurrence of cross-current.

[0099] FIG. 17 is a vector diagram of an INV inverter output voltage. On the left in FIG. 17 shows the load state of the drive, and on the right in FIG. 17 shows the regenerative state of the load. An induction motor (motor) is taken as an example.

[0100] FIG. 17 the following notation is used: I1: primary current, Id: measured current along the d axis, Iq: measured current along the q axis, ω1: component of the angular frequency of the inverter INV (= 2π × frequency at the output of the inverter INV), L1: reactor inductance AC L, Ls: leakage reactance in the motor, R1: motor resistance, V1: output voltage at the motor contacts, E2: induced voltage on the motor, Vac1: voltage drop across the AC reactor L.

[0101] In FIG. 17, V1 + Vac1 is the output voltage of the INV inverter, and V1 is the voltage at the motor terminals. As shown in FIG. 17, a difference arises between the voltage V1 + Vac1 at the inverter output and the voltage V1 at the motor terminals. Commercial power source 1 is connected to motor M via an electromagnetic contactor. Accordingly, measures to match the magnitude and phase of the voltage of the commercial power source 1 and the output voltage V1 + Vac1 of the INV inverter with each other are not enough to reduce the specified voltage difference and prevent cross-current. The crosstalk can be reduced by compensating for the voltage drop Vac1 of the AC reactor L.

[0102] In the drive load state and the regenerative load state in FIG. 17, the voltage drop Vac1 at the AC reactor L is divided into directed along the d axis and along the q axis. In this case, the voltage component along the d axis of the total voltage drop Vac1 at the AC reactor L is equal to ω1 × L1 × (-Iq), and the voltage component along the q axis of the total voltage drop Vac1 at the AC reactor L is equal to ω1 × L1 × Id. The component ω1 × L1 × (-Iq) of the voltage drop along the d axis is superimposed on the command voltage Vd * along the d axis, which is the output of the current control circuit, and the component ω1 × L1 × Id of the voltage drop along the q axis is superimposed on the command voltage Vq * along the q axis.

[0103] In FIG. 18 is a block diagram of a synchronous current control section 4 of a commercial power supply according to an eighth embodiment of the present invention. The synchronous current control section 4 of the commercial power supply according to the eighth embodiment of the present invention, in addition to the components of the synchronous current control section 4 of the commercial power supply according to the seventh embodiment of the present invention further comprises a frequency calculation section 15 and an output voltage error compensation section 16.

[0104] The output voltage error compensation section 16 compensates for the voltage drop across the AC reactor L. The frequency component used in the output voltage error compensation section 16 is obtained by differentiating the phase information element θs provided by the rate of change section 12. In addition, the angular frequency component ω1 is obtained by multiplying the phase information element θs by 2π in the frequency computing section 15.

[0105] An output voltage error compensation section 16 is provided for each of the axes: the d axis and the q axis. In FIG. 19 shows in detail the output voltage error compensation section 16 for the d axis, and FIG. 20 shows in detail the output voltage error compensation section 16 for the q axis.

[0106] As shown in FIG. 19, the output voltage error compensation section 16 along the d axis contains a multiplier 61a multiplying the component of the angular frequency ω1, inductance L1 of the AC reactor and the measured current Iq along the q axis, and a subtractor 62a subtracting the output ω1 × L1 × Iq of the multiplier 61a from the command voltage Vd * along the d axis and outputting the result of subtraction as the final command voltage Vd1 * along the d axis.

[0107] As shown in FIG. 20, the output voltage error compensation section 16 along the q axis contains a multiplier 61b multiplying the component of the angular frequency ω1, inductance L1 of the AC reactor and the measured current Id along the d axis, and an adder 62b summing the output ω1 × L1 × Id of the multiplier 61a and command voltage Vq * along the q axis and outputting the result of subtraction as the final command voltage Vq1 * along the q axis.

[0108] Thus, the compensation of the output voltage is performed in accordance with the component along the d axis equal to ω1 × L1 × (-Iq) of the voltage drop Vac1, and the component along the q axis equal to ω1 × L1 × Id of the voltage drop Vac1.

[0109] In an eighth embodiment of the present invention, the control system or device measures the current at the output of the INV inverter and performs current control to maintain the current equal to the value of the command current. Therefore, the control accuracy is high, and therefore, the control system can effectively prevent cross-current during the switching operation compared with the device described in document 3, which discloses a technical solution for switching synchronization.

[0110] Therefore, switching the drive from the INV inverter to the drive from the commercial power source 1 proceeds smoothly and stably without failures and stopping the power converter due to overcurrent and voltage, as a result, the reliability of the motor drive system is improved.

[0111] Furthermore, compared with the first through seventh embodiments of the present invention, the system takes into account the voltage drop Vac on the AC reactor L and therefore further prevents overcurrent and improves the reliability of the motor drive system.

[0112] [Embodiment 9 of the present invention]

In a ninth embodiment of the present, in the output voltage error compensation section 16, there is a means for creating a dead zone. When the current along the q axis becomes zero in the no-load state, the polarity can completely change due to the superposition of noise on the measured current. In the case of polarity inversion, the correction may deviate from the component for which compensation is required. Therefore, there is a dead zone, which allows you to refrain from compensating for the component due to the current along the q axis in the absence of load or at a small load (that is, when the measured current (currents) Iu, Iv, Iw is lower than a predetermined value).

[0113] In FIG. 21, an output voltage error compensation section 16 is shown with deadband means 63 and without deadband means 63. As shown in FIG. 21, deadband means 63 receives a command current Iq along the q axis and supplies an output signal to multiplier 61a. The output of the deadband tool 63 is zero when the absolute value of Iq is less than or equal to a predetermined value, and equal to Iq when the absolute value of Iq is greater than a predetermined value. In other respects, the ninth embodiment of the present invention is identical in construction to the eighth embodiment of the present invention.

[0114] As stated above, the ninth embodiment of the present invention can provide the same operations and effects as the eighth embodiment of the present invention. In addition, even if noise is superimposed on the measured current (currents) Iu, Iv, Iw when the measured current (currents) Iu, Iv, Iw is lower than a predetermined value, it is possible to prevent an unwanted shift due to noise, which will have to be compensated due to the polarity inversion.

[0115] [Embodiment 10 of the present invention]

In the output voltage error compensation section 16 according to the eighth embodiment of the present invention, command voltages Vd * and Vq *, angular frequency component ω1 and measured currents Id and Iq are used. However, it is desirable to compensate for the voltage drop Vac1 at the AC reactor L using information about command currents Id * and Iq * instead of the measured currents Id and Iq.

[0116] In FIG. 22 is a block diagram of a synchronous current control section 4 of a commercial power supply according to a tenth embodiment of the present invention. We can assume that by controlling the current, the measured currents, Id and Iq, are made equal to the command currents Id * and Iq *. In addition, the values of the measured currents Id and Iq immediately before switching from V / f control to current control are used as command currents Id * and Iq *. Therefore, we can assume that the command currents Id * and Iq * are equivalent to the measured currents.

[0117] As explained above, the tenth embodiment of the present invention can provide the same operations and effects as the eighth and ninth embodiments of the present invention. In addition, when using the command currents Id * and Iq *, it is possible to get rid of disturbances that can enter the measured currents Id and Iq.

[0118] [Embodiment 11 of the present invention]

In FIG. 23 shows an output voltage error compensation section 16 according to an eleventh embodiment of the present invention. In an eleventh embodiment of the present invention, the voltage drop compensation in the AC reactor L is taken into account as a constant value.

[0119] As shown in FIG. 23, the output voltage error compensation section 16 according to the eleventh embodiment of the present invention comprises a multiplier 64, a θcomp calculation section 65, multipliers 66a, 66b, a subtractor 67a, and an adder 67b.

[0120] The multiplier 64 calculates the voltage drop compensation value Vcomp by multiplying the inductance L1 of the AC reactor L, the angular frequency component ω1 and the current I under load conditions of the drive during synchronization with a commercial power source. The θcomp calculation section 65 calculates the θcomp using the command current Id * along the d axis and the command current Iq * along the q axis.

[0121] The multiplier 66a calculates the voltage dip compensation component Vd_comp along the d axis by multiplying the voltage dip compensation value Vcomp and sin (θcomp). Multiplier 66b calculates the voltage drop compensation component Vq_comp along the q axis by multiplying the voltage drop value Vcomp by cos (θcomp).

[0122] Subtractor 67a subtracts the voltage dip compensation component Vd_comp along the d axis from the command voltage Vd * and outputs the result of subtraction as the resulting command voltage Vd1 * along the d axis. Adder 67b adds the voltage dip compensation component Vq_comp along the q axis to the command voltage Vq * along the q axis and outputs the summation result as the resulting command voltage Vq1 * along the q axis.

[0123] A voltage drop compensation amount can be calculated using expression (9) as shown in FIG. 17 for the eighth embodiment of the present invention, if the inductance L1 of the AC reactor L and operating conditions under load during synchronization with the commercial power supply 1 (namely, the current I = √ (Id2 + Iq2) and the angular frequency component ω1 are known. of this method, it is possible to compensate for the voltage drop Vac1 of the AC reactor L without using the current sensor 2 and the frequency calculation section 15 shown in Fig. 18. The voltage drop compensation value is denoted as Vcomp.

[0124]

[0125] The command current Id * along the d axis and the command current Iq * along the q axis are used to project onto the d axis and q axis. In FIG. 24 is a vector diagram showing only command currents Id * and Iq * along the d axis and along the q axis and the voltage drop Vac1 at the AC reactor L. There are no significant differences in drive and regeneration performance. Accordingly, only operation under load of the drive is shown.

[0126] The ratio for projections onto the d axis and q axis is determined by the expression (10):

[0127]

[0128] Conversion to voltage compensation components along the d axis and along the q axis can be performed by calculating the following mathematical expressions (11) and (12) using θ _comp defined by expression (10), as is apparent from FIG. 24. As can be seen from expressions (11) and (12), the voltage compensation component along the d axis is Vd_comp, and the voltage compensation component along the q axis is Vq_comp.

[0129]

[0130]

[0131] The compensation components thus obtained are superimposed respectively on the command voltage Vd * along the d axis and the command voltage Vq * along the q axis, issued by the current control means.

[0132] In the eleventh embodiment of the present invention, the voltage dip compensation component Vd_comp along the d axis and the voltage dip compensation component Vq_comp along the q axis are determined according to the above mathematical expressions (11) and (12), if we consider the angular frequency component ω1, the command current Id * along the d axis and command current Iq * along the q axis are constant. Alternatively, it is preferable to use a method for determining compensation components by defining one of these parameters as a constant value and determining another parameter (s) from the measured quantity (s), as shown in FIG. eighteen.

[0133] As explained above, the eleventh embodiment of the present invention can provide the same operations and effects as the eighth to tenth embodiments of the present invention. In addition, the voltage drop Vac1 at the AC reactor L can be compensated for without the need for a current sensor 2 and in the frequency calculation section 18.

[0134] [Embodiment 12 of the present invention]

In a twelfth embodiment of the present invention, output voltage compensation is performed during V / f control before synchronization is completed. When a twelfth embodiment of the present invention is used, the current control section 6, the output voltage error compensation section 16, and the two phase to three phase conversion section 8 shown in FIG. 18 and FIG. 22 are connected as shown in FIG. 25.

[0135] Thus, as shown in FIG. 25, in a twelfth embodiment of the present invention, a transition switch S5 is installed between the output voltage error compensation section 16 and the two-phase to three-phase conversion section 8. The transition switch S5 receives the command voltage Vd * along the d axis and the command voltage Vq * along the q axis and the final command voltages Vd1 * and Vq1 * along the d axis and along the q axis.

[0136] The transition switch S5 is connected to the off side. during the period during which the current control switching flag is set to zero (i.e., during V / f control). In this state, the switch S5 of the transition gives the final command voltage Vd1 * along the d axis and the final command voltage Vq1 * along the q axis to the section 8 for converting two phases into three phases. During the period when the current control switching flag is set to one (i.e., during the ACR control), the transition switch S5 is connected to the On side. and provides a command voltage Vd * along the d axis and a command voltage Vq * along the q axis to the section for converting two phases into three phases.

[0137] If the compensation of the output voltage error was performed before the completion of synchronization, then after switching to current control, the compensation of the output voltage error is not required.

[0138] During the current control (ACR control), the INV inverter outputs a voltage, including the voltage drop Vac1 at the reactor L. In this case, the measured current information element contains the voltage drop component Vac1 at the AC reactor L, and therefore no voltage error compensation is required .

[0139] According to a twelfth embodiment of the present invention, it is possible to omit complex calculations during current control, simplify the design, and reduce the amount of calculation during current control.

[0140] Although the invention has been described above with respect to certain embodiments thereof, it is not limited to the embodiments described above. In the framework of the technical concept of the present invention, modifications and variations of the embodiments of the present invention described above are possible. These modifications and variations are within the scope of the claims.

Claims (45)

1. A synchronization control device for a power converter for supplying electricity from a commercial power source to an engine, comprising: a first on / off switch installed between the commercial power source and the engine; a serial circuit that is connected in parallel with the first on / off switch and which includes a power converter, an AC reactor, and a second on / off switch; a synchronization control section for controlling the power converter from the moment the engine is started until the output voltage of the commercial power source and the output voltage of the power converter are synchronized with each other; and a control section based on the synchronous current of the commercial power source for controlling the power converter after establishing synchronization between the output voltage of the commercial power source and the output voltage of the power converter; wherein the synchronization control device of the power converter is configured to switch control from the first control of the power converter by the synchronization control section to the second control of the power converter by the control section based on the synchronous current of the commercial power source; wherein the synchronization control section is configured to control the operation of the power converter in the V / f control mode by setting the first on / off switch to the open state and the second on / off switch to the closed state; and the control section based on the synchronous current of the commercial power supply is configured to control the operation of the power converter in the V / f control mode by setting the first on / off switch to the open state and the second on / off switch to the closed state immediately after switching from the first control performed by the power converter synchronization control section to then change the control of the power converter to current control based on ve the measured current at the output of the power converter, and then supply electricity to the engine from both the power converter and the commercial power source by setting the first on / off switch to the closed state, and then supply electricity from the commercial power source to the engine by setting the second on / off switch to an open state. 2. The device according to claim 1, in which the control section based on the synchronous current of a commercial power source contains: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of the three-phase output currents of the power converter, into a measured current along the d axis and a measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; and a section for converting two phases into three phases, intended for converting the command voltage along the d axis and the command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source. 3. The device according to claim 1, in which the control section based on the synchronous current of a commercial power source contains: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of the three-phase output currents of the power converter, into a measured current along the d axis and a measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a section for converting two phases into three phases for converting a command voltage along the d axis and a command voltage along the q axis into three-phase command voltages in accordance with a phase information element of a commercial power source; and a current control section for outputting the three-phase command voltage in accordance with the deviation between the measured three-phase currents and the three-phase command currents. 4. The device according to claim 1, in which the control section based on the synchronous current of a commercial power source contains: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of the three-phase output currents of the power converter, into a measured current along the d axis and a measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; an output voltage error compensation section for outputting the difference obtained by subtracting the product obtained by multiplying the inductance of the AC reactor, the angular frequency component and the measured current along the q axis, from the command voltage along the d axis as the final command voltage along the d axis, and for outputting the sum obtained by adding the product of the inductance of the AC reactor, the angular frequency component and the measured current along the d axis with the command voltage along the q axis as e of the final command voltage along the q axis, and a section for converting two phases into three phases, intended for converting the final command voltage along the d axis and the final command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source. 5. The device according to claim 1, in which the control section based on the synchronous current of a commercial power source contains: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of the three-phase output currents of the power converter, into a measured current along the d axis and a measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; an output voltage error compensation section for outputting the difference obtained by subtracting the product obtained by multiplying the inductance of the alternating current reactor, the components of the angular frequency and command current along the q axis from the command voltage along the d axis, as the final command voltage along the d axis, and for outputting the sum obtained by adding the product of the inductance of the alternating current reactor, the components of the angular frequency and command current along the d axis with the command voltage along the q axis, as the final th command voltage along the axis q, and a section for converting two phases into three phases, intended for converting the final command voltage along the d axis and the final command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source. 6. The device according to claim 1, in which the control section based on the synchronous current of a commercial power source contains: a three-phase to two-phase conversion section for converting three-phase measured currents, which are measured values of the three-phase output currents of the power converter, into a measured current along the d axis and a measured current along the q axis in accordance with the phase information element of a commercial power source; a transition switch for outputting the measured current along the d axis and the measured current along the q axis as a command current along the d axis and the command current along the q axis during the V / f control mode, and outputting the previous command current along the d axis, which is the previous value of the command current along the d axis one sample back, and the previous command current along the q axis, which is the previous value of command current along the q axis one sample back, as the command current along the d axis and command current and along the q axis during current control; a current control section providing command voltage along the d axis and command voltage along the q axis in accordance with the deviation between the current measured along the d axis and command current along the d axis and the deviation between the measured current along the q axis and command current along the q axis; the output voltage error compensation section, designed to calculate the voltage drop compensation value by multiplying the inductance of the AC reactor, the angular frequency component and current in the drive load during synchronization based on a commercial source, with the calculation θcomp = tan ^-1 (command current along the d / axis command current along the q axis) in accordance with the command current along the d axis and the command current along the q axis, to calculate the voltage drop compensation component along the d axis by multiplying the compensation value and voltage drop and sin (θcomp), to calculate the voltage drop compensation component along the q axis by multiplying the voltage drop compensation value and cos (θcomp), with the derivation of the difference obtained by subtracting the voltage drop compensation component along the d axis from the command voltage along the d axis, as the final command voltage along the d axis, and outputting the sum obtained by adding the voltage drop compensation component along the q axis and the command voltage along the q axis, as the final command voltage along the q axis; and a section for converting two phases into three phases for converting the final command voltage along the d axis and the final command voltage along the q axis into three-phase command voltages in accordance with the phase information element of the commercial power source, wherein at least one of the current in the drive load during synchronization based on a commercial power source and the angular frequency component is a constant value. 7. The device according to one of paragraphs. 4-6, in which the output voltage error compensation section is configured to set the current along the q axis to zero if the absolute value of the current along the q axis is less than or equal to a predetermined value, while the current along the q axis is either a measured current along the q axis , or command current along the q axis. 8. The device according to one of paragraphs. 4-7, which further comprises a transition switch for receiving command voltage along the d axis, command voltage along the q axis, final command voltage along the d axis, and final command voltage along the q axis and for outputting the final command voltage along the d axis and the final command voltage along the q axis to the two-phase to three-phase conversion section during the V / f control mode, and command voltage along the d axis and command voltage along the q-axis to the two-phase three-phase conversion section current control belt. 9. The device according to one of paragraphs. 2-6, in which the control section based on the synchronous current of the commercial power supply contains a low-pass filter designed to remove the high-frequency component of the measured current along the d axis and the measured current along the q axis and to supply the measured current along the d axis and the measured current along the q axis into the transition switch. 10. The device according to one of paragraphs. 2-7, in which the control section based on the synchronous current of the commercial power source is configured to reduce the command current along the d axis and the command current along the q axis after a predetermined time period from switching to current control. 11. The device according to claim 10, in which the control section based on the synchronous current of the commercial power source is configured to reduce the command current along the q axis to zero, and then reduce the command current along the d axis to zero. 12. The device according to one of paragraphs. 2-9, in which the control section based on the synchronous current of the commercial power source is configured to smoothly change the information element of the phase of the commercial power source from the output voltage phase of the power converter to the output voltage phase of the commercial power source when there is an error or difference between the phase of the output voltage power converter and output voltage phase of a commercial power source. 13. The device according to one of paragraphs. 2-12, in which the section for converting two phases into three phases is configured to convert the command voltage along the d axis and the command voltage along the q axis into a three-phase command voltage in accordance with the phase of the output voltage of the power converter during the V / f control mode, and convert the command voltage along the d axis and the command voltage along the q axis into a three-phase command voltage in accordance with the phase information element of the commercial power source during current control, and the three-phase to two-phase conversion section is configured to convert the three-phase measured currents to the measured current along the d axis and the measured current along the q axis in accordance with the output voltage phase of the power converter during the V / f control mode and convert the three-phase measured currents to the measured current along the d axis and the measured current along the q axis in accordance with the phase information element of the commercial power source during current control.

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