JP2021019437A - Power supply regenerative converter and processing method therefor - Google Patents

Abstract

To provide a power supply regenerative converter and a processing method therefor, capable of quickly responding to abrupt phase fluctuation or frequency fluctuation.SOLUTION: A power supply regenerative converter is disposed between a three-phase AC power supply and an inverter for performing variable speed control on a motor, and regenerates induced electromotive force generated when the motor decelerates, in the three-phase AC power supply. The power supply regenerative converter includes: AC power supply terminals connected to the three-phase AC power supply; an AC voltage detection unit for detecting three-phase AC voltage at the AC power supply terminals; and a phase estimation unit for estimating phases of the three-phase AC power supply from the three-phase AC voltage detected by the AC voltage detection unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power regenerative converter.

The power supply regeneration converter is a device that is arranged between an inverter device that controls a motor at a variable speed and a three-phase AC power supply, and regenerates an induced electromotive force generated during deceleration of the motor to the three-phase AC power supply.

Patent Document 1 is a background technique in this technical field. In Patent Document 1, the power supply regeneration device includes a power conversion unit, a drive control unit, and a phase adjustment unit, and the phase adjustment unit outputs an AC power supply voltage based on the AC power supply voltage detected on the AC power supply side. It is described that the phase is adjusted based on the increase / decrease of the invalid current flowing between the power conversion unit and the AC power supply. However, since the power regenerative device monitors the voltage of the separate power supply, wiring for that purpose is required separately, and there is a possibility of incorrect wiring or disconnection of the wiring, resulting in increased cost and reliability. Could lead to a decline in

On the other hand, there is Patent Document 2. Patent Document 2 has an AC power supply terminal in which a power supply regeneration converter is connected to an AC power supply, and based on the AC power supply voltage supplied from the AC power supply terminal, the phase detection unit sets the voltage phase of the three-phase AC power supply as the phase voltage. The points to be detected by the zero cross detection of are described.

Japanese Unexamined Patent Publication No. 2013-162543 Japanese Unexamined Patent Publication No. 2004-180427

In a power source powered by a small self-supporting generator, frequency fluctuations occur due to sudden changes in load. Further, even with a general commercial power supply, a phase jump of the power supply voltage may occur when the distribution line route is switched due to a system accident or the like.

Patent Document 2 describes that a power supply voltage zero cross is used as a method for detecting the phase of the power supply voltage. However, zero crossing of the power supply voltage occurs only twice per phase in one cycle. Therefore, it may not be possible to immediately catch and respond to the occurrence of sudden phase changes or frequency fluctuations. As a result, in the power supply voltage phase detection method using zero cross, when a steep phase fluctuation or frequency fluctuation occurs, the timing of switching ON / OFF of the gate signal may deviate from the normal proper position. In this case, the alternating current jumps, causing an overcurrent protection operation and excessive stress on the element. Further, in Patent Document 2, a full-wave rectifier circuit and an A / D converter are separately required for detecting the voltage amplitude, and there is also a problem that the price increases.

The present invention provides a power regenerative converter capable of immediately responding to steep phase fluctuations and frequency fluctuations, and a processing method thereof.

In view of the above background technology and problems, the present invention is arranged between an inverter that controls a motor at a variable speed and a three-phase AC power supply, and three-phase induced electromotive force generated when the motor is decelerated. A power supply regeneration converter that regenerates to an AC power supply, and is detected by an AC power supply terminal connected to a three-phase AC power supply, an AC voltage detector that detects the three-phase AC voltage at the AC power supply terminal, and an AC voltage detector. It has a phase estimation unit that estimates the phase of a three-phase AC power supply from the three-phase AC voltage.

According to the present invention, it is possible to provide a power supply regenerative converter capable of immediately responding to steep phase fluctuations and frequency fluctuations, and a processing method thereof.

It is a block diagram of the power supply regenerative converter in Example 1. FIG. It is a figure which shows the relationship between the three-phase AC voltage and a gate pulse in Example 1. FIG. It is a block diagram of the alternating current detection part in Example 1. FIG. It is a block diagram of the AC voltage detection part in Example 1. FIG. It is a figure which shows the operation waveform at the time of a regenerative operation in Example 1. FIG. It is a figure which shows the conduction state of the element in the three-phase bridge of the power supply regenerative converter in the phase of 0 ° ≤ θ ≤ 60 ° in Example 1. It is a figure which shows the operation waveform at the time of power running operation in Example 1. FIG. It is a figure which shows the operation waveform at the time of stop in Example 1. FIG. It is a flowchart which shows the operation of the phase estimation part in Example 1. FIG. It is a table which shows the formula of the 6 phase intervals of the power supply voltage and the estimated phase in Example 1. It is a block diagram of the phase calculation part in Example 1. FIG. It is a table which shows the formula of 6 phase sections of the power supply voltage and voltage amplitude in Example 1. It is a block diagram of the power supply regenerative converter in the case where the current value is not used for the detection of the power supply voltage phase in Example 2. It is a flowchart which shows the operation of the phase estimation part in Example 2. It is a block diagram in the case where the diode rectifier module on the general-purpose inverter side is used together with the power supply regenerative converter in Example 3. FIG. It is a figure which shows the operation waveform at the time of a regenerative operation in Example 3. It is a figure which shows the operation waveform at the time of power running operation in Example 3. FIG. It is a figure which shows the operation waveform at the time of stop in Example 3. FIG.

Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a power supply regenerative converter in this embodiment. First, a schematic operation will be described. In FIG. 1, the power regenerative converter 1 passes through a three-phase AC power supply 2 that generates three-phase (R-phase, S-phase, T-phase) AC voltage via a three-phase reactor 3 and an AC power supply terminal 11. Be connected. The power regenerative converter 1 has a DC unit provided with an electrolytic capacitor 20, and this DC unit is connected to the DC unit of the inverter 4. The inverter 4 has a converter portion that converts DC power and AC power, and drives the motor 5 by outputting an AC voltage to the motor 5. The AC current detection unit 50 of the power supply regeneration converter 1 generates a three-phase current signal from the signal of the connected two-phase current detector and outputs it to the phase estimation unit 52. The AC voltage detection unit 51 detects the three-phase AC voltage connected via the AC power supply terminal 11 and outputs the three-phase AC voltage to the phase estimation unit 52 and the voltage amplitude calculation unit 54.

The voltage amplitude calculation unit 54 calculates the voltage amplitude VA from the input of the three-phase voltage signal. The phase estimation unit 52 estimates the phase θe from the three-phase AC voltage, the AC current, and the internally calculated phase θs, and inputs the phase θe to the phase calculation unit 53. The phase calculation unit 53 outputs the calculation phase θs from the estimated phase θe. The drive signal generation unit 55 receives the calculated phase θs as an input, generates six gate pulse signals according to the input phase, and outputs the six gate pulse signals to the three-phase bridge circuit 10.

The three-phase bridge circuit 10 is composed of six switching elements (Tr1 to Tr6) and six diodes (D1 to D6), and has two upper and lower elements (hereinafter, referred to as "arms") connected in series. Three are connected in parallel. The three-phase bridge circuit 10 converts AC power and DC power. The DC power at this time is supplied from the capacitor 20.

Here, the phase estimation unit 52, the phase calculation unit 53, the voltage amplitude calculation unit 54, and the drive signal generation unit 55 are realized by software processing by the CPU. That is, those functions are realized by the CPU executing the program stored in the storage device.

Here, FIG. 2 shows the relationship between the three-phase AC voltage waveform (a), the calculated power supply phase θ (b), and the gate pulse signal (c). In FIG. 2, (a) shows three-phase (R-phase, S-phase, T-phase) AC voltage waveforms, T on the horizontal axis is the time of one power supply cycle, and the power supply frequencies are 50 Hz and 60 Hz. , 20 ms and 16.7 ms, respectively. In (b), the 0 point of the power supply phase θ can be set at an arbitrary position with respect to the AC voltage waveform. In the example of FIG. 2, the point where the R-phase voltage is maximized is defined as the 0 point of the phase. At this time, the phase voltage (VgR, VgS, VgT) of each phase is based on the following equation (1), where Va is the maximum value of the phase voltage using the power supply phase θ.
VgR = Va × cos (θ-0 °)
VgS = Va × cos (θ-120 °)
VgT = Va × cos (θ-240 °)
Can be expressed by.

Next, the movement of the switching elements (Tr1 to Tr6) will be described. As shown in FIG. 2C, in each phase, the upper arm switch is turned on in the section of 120 ° where the phase voltage is the maximum among the three phases, and the phase voltage is 120 ° which is the minimum among the three phases. This is a so-called 120 ° energization method in which the lower arm switch is turned on in the section of. In a section other than the above, that is, in a section where the voltage is 120 °, which is the middle of the three phases, both the upper and lower arms are turned off. For example, in the case of R phase, only the switch (Tr1) of the upper arm is turned on in the section from 5T / 6 to T / 6 where the R phase voltage is maximum, and lower in the section from T / 3 to 2T / 3 where it is the minimum. Only the arm switch (Tr2) is turned on, and the switches on both the upper and lower arms are turned off in the other sections.

Next, returning to FIG. 1, the detection of AC current and AC voltage will be described. Let the three-phase alternating current be IR, IS, and IT. Hereinafter, the above voltage and current are considered to be positive in the direction in which they flow out from the neutral point N. At this time, the sum of the currents of the three-phase three-wire system becomes zero, so the following equation (2)
IR + IS + IT = 0 ... (2)
Is established. By using this relationship, the current of the remaining one phase can be calculated from the current values of the two phases.

FIG. 3 is a configuration diagram of the AC current detection unit 50 in this embodiment. In FIG. 3, a signal proportional to the instantaneous value of the alternating current of the main circuit obtained by a current detector or the like is input to the A / D converter to obtain corresponding two-phase digital values, IR and IT. Although the S phase is not provided with a current detector or an A / D converter, IS can be calculated as − (IR + IT) from equation (2).

Next, regarding the AC voltage, the relationship between the voltage on the power regenerative converter side and the power supply voltage will be described. FIG. 4 is a configuration example of the AC voltage detection unit 51 in this embodiment. In FIG. 4, with reference to the neutral point (N) of the power supply, the phase voltage of each phase of the power supply voltage is VgR, VgS, VgT, and the three-phase AC at the AC power supply terminal 11 (power supply regenerative converter end) of the power supply regenerative converter. Let the voltage be VR, VS, VT. Then, assuming that the three-phase reactor 3 is in three-phase equilibrium, the inductance of one phase is L (H) and the resistance is R (Ω). At this time, the three-phase AC voltages VR, VS, and VT at the end of the power regenerative converter take into consideration the voltage drop of the reactor with respect to the power supply voltage, and the following equation (3)
VR = VgR- (R + L x d / dt) x IR
VS = VgS- (R + L × d / dt) × IS
VT = VgT- (R + L x d / dt) x IT
Can be expressed by.

When all the above equations (3) are added and VgR + VgS + VgT = 0 from the equation (1) and IR + IS + IT = 0 of the equation (2) are taken into consideration, VR + VS + VT = 0 is established. Therefore, when the reactor is in three-phase equilibrium, if two phases of the voltage at the power supply regenerative converter end are known, the remaining one phase can also be obtained.

Next, the operation of the AC voltage detection unit 51 will be described. In FIG. 4, the voltage (VR, VS, VT) on the power supply regenerative converter side is input to the AC voltage detection unit 51. This input voltage is divided by resistors R1 and R2 provided between the reference points L (ground on the substrate). Here, it is assumed that the reference point L has a voltage of VL when viewed from the neutral point. Let the voltage dividing values of each of the three phases viewed from the reference point L be VmR, VmS, and VmT. In FIG. 4, this divided voltage is input to the voltage follower. The output voltage of the voltage follower matches the input voltage, and the output voltage of the voltage follower is also VmR, VmS, and VmT. The voltage follower can be eliminated if the influence of the impedance of the circuit in the subsequent stage is acceptable. Assuming that the resistors of the voltage divider circuit are R1 and R2, the voltage divider ratio k is represented by k = R2 / (R1 + R2). As a result, the voltage dividing voltage of each phase with reference to L in FIG. 4 is
VmR = k (VR-VL)
VmS = k (VS-VL)
VmT = k (VT-VL)
Will be. This divided voltage (VmR, VmS, VmT) is first used for the output of the neutral point voltage VmN.

Here, the voltage of VmN is based on the Hoashi-Millman's theorem with reference to L in FIG.
VmN = (VmR + VmS + VmT) / 6 = k (VR + VS + VT-3VL) / 6 = -k * VL / 2
Will be. Next, the divided voltage of the R phase and the T phase is input to the A / D converter via the operational amplifier circuit.
This operational amplifier circuit is a differential amplifier circuit, and the input voltages VadR and VadT to the R-phase and T-phase A / D converters are represented below.
VadR = 2 x VmN-VmR = -k x VL-k (VR-VL) = -kVR
VadT = 2 x VmN-VmT = -k x VL-k (VT-VL) = -kVT
Therefore, a voltage obtained by dividing (k times) the voltages VR, VS, and VT from the neutral point N is input to the A / D converter regardless of the voltage at the reference point L. By A / D converting these VadR and VadT and multiplying them by appropriate coefficients, digital values VdR and VdT proportional to each of VR and VT can be obtained. Let G be this proportional gain
VdR = G × VR
VdT = G × VT
Therefore, VdS can be expressed by the following equation by VdR and VdT.
VdS = G × VS = G × (-VR-VT) = -VdR-VdT
Further, of course, it is also possible to generate VadS and perform A / D conversion to obtain it in the same manner as VadR and VadT. The circuit of FIG. 4 can be added on the substrate constituting the existing main circuit at the minimum cost. On the other hand, it is also possible to use an instrument transformer or the like instead of the resistance voltage divider and use the output as an input signal to the A / D converter.

Next, in order to explain the operation of the phase estimation unit 52, the power supply voltage (VgR, VgS, VgT), the power supply regenerative converter end voltage (VR, VS, VT), and the alternating current (IR, IS, IT) are used for each operating condition. ) Is explained. Hereinafter, in FIGS. 5, 7, and 8, it is assumed that the line voltage effective value of the power supply voltage is 200 V.

FIG. 5 shows an example of the waveform during the operation of the power supply regenerative converter when the inverter is in the regenerative operation. In FIG. 5, (a) shows the power supply voltage, (b) shows the power supply regenerative converter end voltage, and (c) shows the alternating current. At this time, the power supply regeneration converter 1 is performing the Tr switching operation shown in FIG. 2, and the inverter 4 is operating the motor in the regenerative state. At this time, the DC voltage becomes equal to or larger than the amplitude of the line voltage of the AC voltage. Therefore, D1 to D6 do not conduct regardless of the phase of the AC voltage. On the other hand, the continuity of Tr1 to Tr6 is such that Tr conducts according to the command of FIG. For a certain phase, there is a phase in which neither the upper and lower arms are conducting, but in this case, the current of that phase becomes 0 (see the dotted line indicated by 95).

FIG. 6 shows the conduction state and the current state of the elements of the three-phase bridge circuit when the inverter is in regenerative operation. FIG. 6 shows a case where 0 ° <θ <60 ° (T / 6), where 0 is the phase at which the R phase is maximized. For the sake of clarity, the parts where neither the switching element nor the diode are conducting are marked with a cross and the wiring is omitted. When the phase θ is 0 ° <θ <60 °, Tr1 and Tr6 are conductive as shown in FIG. 6 and become constant at IS = 0. As a result, by substituting IS = 0 and dIs / dt = 0 for VS in the equation (3), VgS = VS, and in the S phase, the power supply voltage and the power supply regenerative converter side voltage match.

From the above, during the regenerative operation as shown in FIG. 5, the current of the phase in which the voltage is in the middle of the three phases (hereinafter referred to as the intermediate phase) becomes 0. At this time, the voltage is the same at the power supply side and the power supply regenerative converter end. Further, a steep current change occurs at the moment when the Tr switch is switched, and at this moment, the voltage on the power supply side and the voltage at the power supply regenerative converter end do not match.

Next, FIG. 7 shows an example of a waveform during power regenerative converter operation when the inverter is power running. In FIG. 7, similarly to FIG. 5, (a) shows the power supply voltage, (b) shows the power supply regenerative converter end voltage, and (c) shows the alternating current. At this time, the power supply regenerative converter is performing the Tr switching operation shown in FIG. 2, and the inverter is operating the motor in a power running state. At this time, the DC voltage becomes lower than the peak value of the line voltage amplitude. Tr1 to Tr6 conduct with each other according to the command shown in FIG. 2 as in the regenerative operation. Unlike during regenerative operation, D1 to D6 conduct in a phase in which the instantaneous value of the line voltage exceeds the DC voltage. As a result, the current does not necessarily become 0 even in the phase in which both the upper and lower arms are not conducting. For example, in the power supply voltage during the time from T / 6 to T / 3, the R phase is the intermediate phase, but at the beginning of this section, D2 and D5 are conducting and a current is flowing in the R phase. As a result, the power supply voltage and the power supply regenerative converter end voltage do not match at the beginning of this section. However, the current becomes 0 in the remaining portion, and the power supply voltage and the power supply regenerative converter end voltage match. From the above, during power regenerative converter operation when the inverter is power running as shown in FIG. 7, there is a region where the current does not become 0 even if the voltage is in the middle of the three phases. Exists (see inside the dotted line indicated by 96). However, the voltage of the phase in which the current is 0 coincides with the power supply side at the power supply regenerative converter end. Further, when the current of the intermediate phase is not 0, the voltages of two of the three phases are the same.

Next, FIG. 8 shows an example of the waveform when the power regenerative converter is stopped. In FIG. 8, similarly to FIG. 5, (a) shows the power supply voltage, (b) shows the power supply regenerative converter end voltage, and (c) shows the alternating current. When the power regenerative converter is stopped, the inverter can be power-running, but on the other hand, the regenerative operation does not occur under normal operating conditions because the DC voltage rises and leads to protection operation such as overvoltage. In FIG. 8, the load consumption on the DC side gradually decreases with time.

When the power regenerative converter is stopped, no switching command is issued and Tr1 to Tr6 are not conducting. However, D1 to D6 conduct in a phase in which the instantaneous value of the line voltage exceeds the DC voltage as in the power running operation. Therefore, in a state where the inverter is power-running and DC power is consumed, or when the voltage of the main circuit capacitor immediately after the power is turned on is low, a large current flows and the conduction time becomes long. When the inverter is stopped, the DC power consumption is low and the diode conduction time is short. FIG. 8C shows the current waveform when the main circuit capacitor is charged, and the current value from 0 to T / 6, which was in a low voltage state, is 5T / 6 to T, which is charged to some extent. Is greater than the current value up to.

Regarding the current and voltage of the intermediate phase, the current flows in the R phase, which is the intermediate phase, in the region from T / 6 to T / 3, where the capacitor voltage is low, and as a result, the power supply voltage and the power supply regenerative converter side voltage do not match. However, in the region of 2T / 3 to 5T / 6, where the capacitor is charged to some extent and the load consumption of DC power is small, no current flows in the R phase, which is the intermediate phase, and as a result, the power supply voltage and the power supply regenerative converter side voltage Are in agreement.

From the above, when the power regenerative converter is stopped when the inverter is in power running as shown in FIG. 8, there is a region where the current does not become 0 even if the voltage is in the middle of the three phases. Exists (see inside the dotted line indicated by 97). However, the voltage of the phase in which the current is 0 is the same at the power supply side and the power supply regenerative converter end.

Next, the operation of the phase estimation unit 52 will be described. As shown in FIG. 1, the phase estimation unit 52 inputs the voltage (VR, VS, VT), AC current (IR, IS, IT), voltage amplitude (VA), and calculated phase (θs) at the power supply regeneration converter end. As a result, the estimated phase (θe) estimated from the voltage at the end of the power supply regeneration converter is output.

FIG. 9 is a flowchart showing an operation example of the phase estimation unit 52. In FIG. 9, first, the magnitude relationship of the phase voltage of each phase is switched depending on the phase of the power supply. This change of magnitude relation occurs every 60 °, and the entire phase from 0 ° to 360 ° is divided into six sections. Further, the conduction state of Tr1 to Tr6 shown in FIG. 2 also changes in this region. This is taken as a phase interval and is shown in FIG.

As shown in FIGS. 5, 7 and 8, the voltage of the intermediate phase coincides with the voltage at the end of the power regenerative converter and the power supply voltage except for specific conditions. Therefore, in order to estimate the phase of the power supply voltage from the voltage at the end of the power supply regenerative converter, a phase section is specified and the voltage of the intermediate phase in that section is considered. In order to specify this phase interval, the calculation phase (θs) input from the phase calculation unit 53 in the subsequent stage is used. The operation of the phase calculation unit 53 will be described later, but this calculation phase (θs) detects the phase of the power supply voltage with almost accuracy except at the time of transient response at the time of start-up or power supply disturbance. Therefore, the phase interval can be specified based on the phase range shown in the table of FIG. After specifying the phase interval in step S10, it is then determined in step S11 whether it is the end of the phase interval. That is, as shown in the explanation of FIG. 5, a voltage jump occurs at the boundary of the phase section due to a sudden current change. This region can be determined by whether or not the calculated phase (θs) is near the end of the section, that is, the boundary of the phase section. If it is the end of the phase interval, the process ends in step S12 with its own calculated phase (θs) as the estimated phase (θe). This makes it possible to avoid phase estimation with discontinuous voltage values occurring at the boundaries of each section in FIG.

If it is not the end of the phase section in step S11, it is determined in step S13 whether or not the current of the intermediate phase determined in each section is zero. If the current of the intermediate phase is not 0, the process ends in step S12 with its own calculated phase (θs) as the estimated phase (θe).

If the current of the intermediate phase is 0, the power supply voltage of that phase and the end voltage of the power supply regenerative converter are the same as described above. At this time, the phase can be calculated from the equation (1) using the inverse trigonometric function. For example, in the case of the phase section 1, since S is the intermediate phase, it is determined whether or not the current IS of the S phase is 0. If IS = 0, VgS = VS is established and this is substituted into the S phase equation of equation (1). Then
VS = VAcos (θ-120 °)
Will be. When this is solved for θ,
θ = cos ^-1 (VS / VA) + 120 °
Two of the above solutions can be obtained, but the one that satisfies 0 ° ≤ θ <60 in the interval 1 is defined as the estimated phase.

As described above, the intermediate phase corresponding to the power supply voltage is constantly replaced every 60 °, but is always continuously present except for specific conditions. It is possible to estimate the phase from the voltage signal of this intermediate phase. Alternatively, in the case of discrete processing by a microcomputer, calculation can be performed at an arbitrary cycle.

Therefore, according to FIG. 10 in which the estimated phase is calculated from the phase interval as described above, the phase interval is determined in steps 14 to 16, and the estimated phase corresponding to the phase interval is output in steps 17 to 19 for processing. finish.

In addition, there is a region where phase estimation is impossible, such as when the inverter is operated by power running. However, this is at most a part of the end of each section, and by outputting the phase calculated from the current phase and frequency as described later, the phase synchronization is properly maintained if the power supply is in the steady state. It is possible. In this way, it is possible to synchronize the phase with the power supply regardless of whether the power supply regeneration converter is started or stopped. In particular, while the power regenerative converter is in operation, it does not depend on the operating state of the inverter.

FIG. 11 is a block configuration diagram of the phase calculation unit 53. The phase calculation unit 53 is a block that calculates an calculation phase (θs) that matches the power supply phase by using the estimated estimated phase (θe) as an input. In this control block, the frequency (ω) and the phase (θs) are held internally, and the phase synchronization processing is performed so that the frequency (ω) and the calculated phase (θs) match the frequency and phase of the power supply. It has been In this block, first, the calculated phase (θs) and the estimated phase (θe) are compared, and the difference (error) is input to the proportional integration compensator (PI). At this time, the output of this proportional integration compensator (PI) is a frequency. When the calculated phase (θs) and the estimated phase (θe) match, the input to the proportional integration compensator (PI) becomes 0, and the current frequency (integrated value) is maintained. If there is a deviation between the calculated phase (θs) and the estimated phase (θe), the difference is input to the proportional integration compensator (PI), and as a result, the frequency is adjusted in the direction in which the deviation becomes smaller. For example, when the estimated phase (θe) is larger than the calculated phase (θs), the frequency becomes large due to the positive difference (error). On the contrary, when the estimated phase (θe) is smaller than the calculated phase (θs), correction is applied so that the frequency becomes smaller due to a negative difference (error). The calculated phase (θs) is determined by adding an increment value proportional to frequency and time to the current phase. In this way, the frequency (ω) and the calculated phase (θs) of this block converge to a value that matches the frequency and phase of the power supply.

Next, the operation of the voltage amplitude calculation unit 54 will be described. Similar to the phase estimation unit 52, a section is specified, and attention is paid to the power supply voltage given in that section. At this time, the slope can be obtained by differentiating this signal. For example, if the VS equation that holds for section 1 is θ = ωt,
VS = Va × cos (ωt-120 °)
dVS / dt = -ωVasin (ωt-120 °)
If the change in VS is ΔV at the time of ΔT,
ΔV / ΔT = −ωVa × sin (ω (t + ΔT) −120 °)
ΔV / ΔT = −ωVa × sin (θ + ΔTω−120 °)
Here, for the sake of simplicity, it is considered that the calculation is performed by the zero cross of VS. In the case of interval 1, zero cross occurs at the point of θ = π / 6, so substitute θ = 30 ° and substitute.
ΔV / ΔT = −ωVa × sin (30 ° + ΔTω−120 °)
Therefore,
ΔV / ΔT = ωVa × cos (ΔTω)
Here, if ΔT is sufficiently small, it can be approximated as cos (ΔTω) = 1, so that
ΔV / ΔT = ωVa, thus Va = ΔV / (ΔTω).

By performing the same calculation for other sections, the amplitude calculation formula shown in FIG. 12 can be obtained. As ω in the above equation, the one held by the phase calculation unit may be used. The error of cos (ΔTω) = 1 is about 4.9% at 1 ms and 0.8% at 400 μs when the power supply is 50 Hz. In this way, if the detection is limited to the zero cross point, the amplitude can be obtained by a simple calculation as described above.

As described above, according to the present embodiment, the power supply voltage signal is detected by inputting a signal proportional to the instantaneous voltage of the three-phase AC voltage at the power supply regeneration converter end to the A / D converter, and the software processing by the CPU is performed. , Perform phase estimation using a triangular function. As a result, continuous phase detection is possible, phase synchronization with the power supply is obtained, continuous voltage monitoring is possible, and a quick response to power supply phase jump and frequency disturbance is possible. At the same time, the AC voltage amplitude can be detected without the need for an additional full-wave rectifier circuit or the like. Furthermore, the AC voltage amplitude of each phase can be estimated only from the two-phase AC voltage, the AC voltage amplitude can be obtained for each of the three phases, and the unbalanced state of the power supply voltage can be grasped. In addition, in the power supply regenerative converter connected to the power supply via the reactor, the AC power supply voltage is detected based on the power supply input to the AC power supply terminal of the power supply regeneration converter, so when monitoring the voltage of a separate power supply. The wiring required for is not required. As a result, it is possible to reduce parts such as wire rods and terminal blocks, and improve reliability by eliminating the possibility of incorrect wiring or disconnection failure.

In this embodiment, an example in which the current value is not used for detecting the power supply voltage phase will be described.

FIG. 13 is a block diagram showing a configuration example of the power supply regenerative converter in this embodiment. In FIG. 13, the same configurations as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The difference from FIG. 1 in FIG. 13 is that there is no AC current detection unit 50 and a phase estimation unit 56 that does not require an AC current input.

FIG. 14 is a flowchart illustrating the operation of the phase estimation unit 56 in this embodiment. In FIG. 14, the same configurations as those in FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted. Unlike the phase estimation unit 52, the phase estimation unit 56 in this embodiment does not require a current input.

First, in step S20, attention is paid to three voltage differences from the three-phase voltage of the input power supply regenerative converter end voltage. That is, when any of the three voltage differences falls below a certain value, it is determined that a current is flowing in the intermediate phase. In that case, the operation phase (θs) of itself is output as the estimated phase in step S12, and the process is terminated. The threshold value at this time may be, for example, about several% of the rated AC voltage in consideration of an error in voltage detection and the like.

If any of the three voltage differences is greater than or equal to a certain value, the intermediate phase in which the voltage is between the other two is specified in steps S21 to S23, and the estimated phase depends on which phase the intermediate phase is. To determine. That is, since the voltage of the intermediate phase matches the voltage of the power supply, the phase can be estimated by using the equation (1) as in steps S17 to S19 in FIG. In determining the estimated phase in steps S17 to S19, a value close to the current calculation phase (θs) is selected from the two solutions.

The difference between the phase estimation unit 52 and the phase estimation unit 56 will be described. In the central part of each phase section, the magnitude relationship between the voltage on the power supply side (VgR, VgS, VgT) and the voltage at the end of the power supply regenerative converter (VR, VS, VT) does not depend on the operating state of the power supply regenerative converter or inverter. There is no difference in the operation of the phase estimation unit 52 and the phase estimation unit 56 because they match and no current is flowing in the selected intermediate phase. On the other hand, at the boundary of each section, the magnitude relationship between the voltage on the power supply side (VgR, VgS, VgT) and the voltage at the power supply regenerative converter end (VR, VS, VT) does not match depending on the operating state. Consider the difference between the two operations at this time.

First, at the start end of each section during power running operation in FIG. 7, a current remains in the intermediate phase, and as a result, the voltages of the two phases are equal. As a result, the phase estimation unit 56 outputs the calculated phase (θs). In the case of the phase estimation unit 52, the section 2 is correctly determined under the condition of VT <VR ≦ VS, but since the current is flowing in the intermediate phase, the calculated phase (θs) is output after all. Therefore, the outputs of the phase estimation unit 56 and the phase estimation unit 52 match.

Next, consider immediately after T / 6 at the time of stop in FIG. 8 (starting portion of section 2). The voltage at the end of the power regenerative converter differs in magnitude from the power supply voltage, and VT <VS <VR. In the case of the phase estimation unit 52, the section 2 is determined, but since the current is flowing in the intermediate phase, the calculated phase (θs) is output after all. The phase estimation unit 56 determines that the section 1 is based on the magnitude relationship, but since the voltage of the intermediate phase also matches the voltage of the power supply, the estimation by the equation (1) is possible. At this time, it should be noted that the correct phase of the two solutions of the equation (1) is the start portion of the section 2 and exceeds the phase range of the section 1. As shown in the flowchart of FIG. 14, one that is close to the current phase θs may be selected, or one that exists in a region in which the phase section of section 1 is widened by about 30 ° may be selected. Under this condition, although the operations of the phase estimation unit 56 and the phase estimation unit 52 are slightly different, both of them can appropriately maintain the phase synchronization if the power supply is in the steady state.

In this embodiment, an example in which a general-purpose inverter diode module is used together with the power regenerative converter will be described.

FIG. 15 is a block diagram of the case where the diode module of the general-purpose inverter is used together with the power supply regenerative converter in this embodiment.

As shown in FIG. 15, the diode module 6 of the general-purpose inverter is connected to the power supply 2 side of the three-phase reactor 3 connected to the power supply regenerative converter 1. The diode module 6 of this general-purpose inverter can only convert power by power running, and current in the regenerative direction does not flow. Here, a part of the current in the power running direction supplied through the general-purpose inverter diode module 6 is regenerated to the power supply side as the current in the regeneration direction of the power supply regeneration converter 1. This current is hereinafter referred to as a circulating current.

The current waveforms in this embodiment are shown in FIGS. 16, 17, and 18. 16 is a diagram showing an operation waveform during regenerative operation, FIG. 17 is a diagram showing an operation waveform during power running operation, and FIG. 18 is a diagram showing an operation waveform during stop operation. In each of FIGS. 16, 17, and 18, similarly to FIG. 5, (a) shows the power supply voltage, (b) shows the power supply regenerative converter end voltage, and (c) shows the alternating current.

The current waveform (c) during the regenerative operation of FIG. 16 is substantially the same as that of FIG. 5 (c), which is the current waveform during the regenerative operation of the first embodiment, although the current increases by the circulation. Therefore, the same processing as in the first and second embodiments can be used.

Since the current (c) during power running operation in FIG. 17 is the circulating current, the current flowing through the power supply regenerative converter 1 portion is in the regenerative direction even when the inverter is power running. Therefore, it does not match the current waveform (c) of the power running operation of the first embodiment, but rather is closer to the current waveform (c) of the regenerative operation of FIG. Further, as shown in FIGS. 16 to 18, when the diode module of the general-purpose inverter is combined with the power supply regenerative converter in this embodiment, it can be seen that no current flows in the intermediate phase.

FIG. 18C is a current waveform when the inverter is in power running operation and the power supply regenerative converter is not in operation. In this case, the current in the regeneration direction does not flow to the power supply regeneration converter side. However, most of the power in the power running direction of the inverter is supplied from the diode module of the general-purpose inverter, but a very small current in the power running direction is also generated on the power regenerative converter side. As a result, the waveform is the same as that of the portion where the power running power of FIG. 8C of Example 1 is reduced.

As described above, it can be seen that the configuration of this embodiment is the same as that of the above embodiment, especially when the phase estimation process is considered. When the phase synchronization of the first embodiment is performed, in this case, no current flows in the phase selected in the middle, so that there is always no determination of the presence or absence of the current in the phase selected in the middle on the flowchart of the phase estimation unit 52. It is judged. However, there is no problem in the phase estimation operation, and the same phase synchronization as in the first embodiment can be performed according to the flowchart.

Further, the phase synchronization of the second embodiment can be similarly performed for the waveforms shown in FIGS. 16, 17, and 18. Further, the amplitude calculation shown in the first embodiment can be similarly applied to the waveforms shown in FIGS. 16, 17, and 18.

Although the examples have been described above, the present invention is not limited to the above-mentioned examples, and various modifications are included. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration. Further, each of the above configurations, functions, processing units, processing means and the like may be realized by hardware by designing a part or all of them by, for example, an integrated circuit.

1: Power supply regenerative converter, 2: Three-phase AC power supply, 3: Three-phase reactor, 4: Inverter, 5: Motor, 6: Diode module, 10: Three-phase bridge circuit, 11: AC power supply terminal, 20: Electrolytic capacitor, 50: AC current detection unit, 51: AC voltage detection unit, 52: Phase estimation unit, 53, 56: Phase calculation unit, 54: Voltage amplitude calculation unit, 55: Drive signal generation unit.

Claims (10)

A power regenerative converter that is arranged between an inverter that controls a motor at variable speed and a three-phase AC power supply, and regenerates the induced electromotive force generated during deceleration of the motor to the three-phase AC power supply.
An AC power supply terminal connected to the three-phase AC power supply,
An AC voltage detector that detects three-phase AC voltage at the AC power supply terminal,
A power supply regeneration converter having a phase estimation unit that estimates the phase of the three-phase AC power supply from the three-phase AC voltage detected by the AC voltage detection unit. The power regenerative converter according to claim 1.
It has an AC current detector that detects three-phase AC current from the two-phase current value at the AC power supply terminal connected to the three-phase AC power supply.
The phase estimation unit identifies a phase section of the three-phase AC voltage, and when no current is flowing in the intermediate phase in which the voltage in the phase section is in the middle of the three phases, the phase estimation unit is used from the three-phase AC voltage. A power supply regeneration converter characterized by estimating the phase of the three-phase AC power supply. The power regenerative converter according to claim 1.
The phase estimation unit identifies a phase section when the three voltage differences between the three-phase AC voltages are equal to or greater than a predetermined value, and a current flows through an intermediate phase in which the voltage in the phase section is intermediate between the three phases. A power supply regeneration converter characterized in that the phase of the three-phase AC power supply is estimated from the three-phase AC voltage when the three-phase AC voltage is not used. The power regenerative converter according to claim 2 or 3.
The AC voltage detection unit digitally converts the three-phase AC voltage at the AC power supply terminal via an A / D converter, and detects the digital value of the three-phase AC voltage.
The phase estimation unit is a power supply regenerative converter characterized in that it is executed by software processing. The power regenerative converter according to claim 2 or 3.
Three-phase bridge circuit and
It has a voltage amplitude calculation unit that calculates the voltage amplitude from the three-phase AC voltage.
The phase estimation unit outputs an estimated phase θe from the three-phase AC voltage, the three-phase AC current, the voltage amplitude, and the calculated phase θs.
A phase calculation unit that outputs the calculation phase θs from the estimated phase θe and feeds back the calculation phase θs to the phase estimation unit.
A power supply regenerative converter characterized by having a drive signal generator that takes the calculated phase θs as an input, generates six gate pulse signals according to the input phase, and outputs the six gate pulse signals to the three-phase bridge circuit. It is arranged between the inverter that controls the motor at variable speed and the three-phase AC power supply, the voltage from the three-phase AC power supply is applied to the three-phase bridge circuit, and the induced electromotive force generated during deceleration of the motor is applied to the three-phase bridge circuit. It is a processing method of a power supply regeneration converter that regenerates to an AC power supply.
Detecting the three-phase AC voltage from the three-phase AC power supply applied to the three-phase bridge circuit,
A processing method of a power supply regenerative converter, characterized in that the phase of the three-phase AC power supply is estimated from the detected three-phase AC voltage. The processing method of the power regenerative converter according to claim 6.
The three-phase AC current is detected from the two-phase current value from the three-phase AC power supply applied to the three-phase bridge circuit.
When the phase section of the three-phase AC voltage is specified and no current is flowing in the intermediate phase in which the voltage in the phase section is in the middle of the three phases, the three-phase AC power supply is converted from the three-phase AC voltage. A processing method for a power regenerative converter, which comprises estimating the phase. The processing method of the power regenerative converter according to claim 6.
When the three voltage differences between the three-phase AC voltages are equal to or greater than a predetermined value, a phase section is specified, and when no current is flowing in the intermediate phase in which the voltage in the phase section is in the middle of the three phases, the above. A processing method of a power supply regeneration converter, characterized in that the phase of the three-phase AC power supply is estimated from a three-phase AC voltage. The processing method of the power regenerative converter according to claim 7 or 8.
The three-phase AC voltage from the three-phase AC power supply applied to the three-phase bridge circuit is digitally converted via an A / D converter, and the three-phase AC voltage is a digital value.
A processing method of a power regenerative converter, characterized in that the phase estimation is performed by software processing. The processing method of the power regenerative converter according to claim 7 or 8.
The voltage amplitude is calculated from the three-phase AC voltage,
In the phase estimation, the estimated phase θe is output from the three-phase AC voltage, the three-phase AC current, the voltage amplitude, and the calculated phase θs.
The calculated phase θs is calculated from the estimated phase θe and fed back to the calculated phase θs for estimating the estimated phase θe.
A processing method of a power supply regeneration converter, characterized in that six gate pulse signals corresponding to the input phase are generated with the calculated phase θs as an input, and the six gate pulse signals are output to the three-phase bridge circuit.

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