JP6323270B2 - Magnetic pole position estimation method for cell multi-voltage type inverter - Google Patents

Description

  The present invention relates to a magnetic pole position estimation method for a cell multiple voltage type inverter, and more particularly to a magnetic pole position estimation method for reducing an error between an estimated value and an actual magnetic pole position when estimating the magnetic pole position at the start of a PM motor. is there.

  One of the circuit systems constituting the inverter is a serial multiplexing system. In the serial multiplex system, the DC link unit is not a single inverter as in the conventional 2-level or 3-level, but has a plurality of DC link units insulated by an input transformer, and a single-phase inverter called a cell unit is multi-staged. By connecting, it is possible to output the total DC voltage for the number of connected stages.

FIG. 5 shows an example of a series of three stages and three phases. The DC voltage of each cell unit is represented by Vdc, U, V, and W phase cell units as U1, U2, U3, V1, V2, V3, W1, respectively. If W2 and W3, the load of the inverter is Load, and the load terminal voltage is Vu, Vv, and Vw, Vu is the sum of the voltages of U1, U2, and U3, so the following equation is obtained.
Vu = Vu1 + Vu2 + Vu3
FIG. 6 shows an example of the main circuit configuration of the cell unit. U is the upper arm switching element of the leg connected to the upper stage, X is the lower arm switching element of the leg connected to the upper stage, V is the upper arm switching element of the leg connected to the lower stage, and Y is connected to the lower stage It is a switching element of the lower arm of the leg.

  In general, when driving a PM motor, a position sensor is attached to a rotating shaft to detect the magnetic pole position. However, the position sensor has a built-in electronic circuit, so the environmental resistance is low and the price is low. Has problems such as high. Therefore, in addition to the method using such a position sensor, the position is estimated by estimating the magnetic flux from the output voltage or the voltage command and the current detection information as known in Patent Document 1 and the like. Therefore, a position sensorless control method for estimating the phase of the magnetic pole is also known.

  In the position sensorless control method, a method is used in which a high frequency or a pulse current is passed during start-up to measure the inductance and estimate the position. In the PM motor, the magnetic field pole having a high magnetic permeability is made of a material such as a silicon steel plate and a permanent magnet having a low magnetic permeability, so that the inductance of the magnetic pole axis (d axis) and the axis orthogonal to it (q axis) is reduced. The difference is caused by the asymmetry of the shape. The above method estimates the position using the difference in inductance, and is called a pulse application method, a high frequency application method, a high frequency superposition method, or the like.

FIG. 7 shows an example of current response when a pulse voltage is applied.
When a pulse voltage having a time width ΔT and a voltage width ΔV is applied to the inductance L load, the current change is a differential expression of the expression (1).
ΔV / L = (dI / dT) (1)
Thus, the inductance L component can be obtained from the equation (1) by measuring the differential amount of the current during the ΔT period. Further, the inductance L can be obtained by the equation (2) obtained by obtaining the current change amount before and after the ΔT period and approximating the difference.
L = (ΔT · ΔV) / ΔI (2)
Although it appears in one dimension in FIG. 7, since the PM motor is in a two-dimensional space, it is actually applied to a vector voltage.

FIG. 8 shows an example in which three types of pulse voltage vectors ΔVa, ΔVb, and ΔVc are applied with different phases. Since the relative permeability of the permanent magnet is significantly smaller than that of the iron core material, the d-axis inductance is smaller than the q-axis. That is, the relationship Lq> Ld is established. Therefore, the current difference generated by this voltage component has a larger amplitude near the d-axis, such as ΔIa, ΔIb, ΔIc, and a smaller amplitude near the q-axis. The characteristic is an elliptical axis.
Further, the phase difference Δθa, Δθb, Δθc is generated in the current difference vector in the direction approaching the d-axis with respect to the phase of the applied pulse voltage.

  As shown in FIG. 9, the current difference vector when the pulse voltage is applied to the phase of the entire circumference of the PM motor is as shown in FIG. Thus, there is a method for estimating the magnetic pole position from the current information obtained by applying the pulse voltage.

JP2012-213293

  In the cell multiple voltage source inverter, each cell is composed of a single-phase inverter, and therefore the voltage charged in each DC link capacitor differs due to individual differences. Considering the case of estimating the magnetic pole position by applying a pulse voltage to such an inverter, when the pulse voltage is applied, the cell unit that outputs the voltage is different each time as shown in FIG. The DC voltages of the cell units are not necessarily all equal. Thus, when there is a difference in the voltage of the cell unit to be output, the applied pulse voltage becomes uneven as shown in FIG. FIG. 11B shows the case where the pulse voltage amplitudes of the U-phase cells are the same, and FIG. 11C shows the case where the pulse voltage application periods are different.

  As shown in FIG. 12, when the pulse voltages of (1) and (2) are unequal, the current information obtained may be different from what is originally desired. Considering the case where a pulse voltage as shown in FIG. 12 is applied, a current difference vector as shown in FIG. 13 is obtained. Originally, the current difference vector as shown in FIG. 10 can be obtained and the magnetic pole position can be estimated successfully. However, the current vector in the direction of the magnetic pole position becomes small and it is difficult to estimate the actual magnetic pole position.

  In the case of FIG. 13, the determination of the NS pole is wrong and the position of the magnetic pole that is actually desired is reversed 180 degrees. If driven as it is, there is a possibility that runaway or step-out occurs and the operation cannot be continued.

  Therefore, an object of the present invention is to provide a magnetic pole position estimation method for a cell multiple voltage type inverter that equalizes the amplitude width of the pulse voltage as shown in FIG.

The present invention controls a PM motor with a three-phase inverter in which a plurality of cell units are connected in series. From a signal input via a CPS control unit using a CPS control method (carrier phase select control method). In the method of selecting the switching pattern of the cell unit by the output cell determination unit, outputting a selection signal to the gate of each cell unit, and estimating the magnetic pole position by applying a pulse voltage to the PM motor when starting the PM motor.
The output cell determination unit
The DC voltage of each cell unit determined by determining the number of stages of each phase cell unit connected in series from the amplitude and pulse phase of the pulse voltage is arranged in ascending order for each phase, and each phase cell unit is arranged for each arranged order. Set the hour group,
A group in which each phase cell unit can have a combination of two phases from a group with one phase cell unit is set,
Each set of phase cell unit groups is set to 1 time and 2 times to obtain a voltage variation deviation for each group and extract the minimum deviation group,
The extracted minimum deviation group is used as an estimated value of the magnetic pole position when the magnetic pole position is estimated.

  The extracted estimated value of the magnetic pole position in claim 1 is stored in an immobilization table of the output cell unit, and the output cell unit during application of the pulse voltage is immobilized.

In addition, the output cell unit immobilization table according to claim 1 or 2 includes:
A table number corresponding to the number of stages of each phase cell unit is attached, and the magnetic pole position is estimated by selecting the attached table number.

Further, according to the present invention, the fixing of the output cell unit to the fixing table is
Determine the number of times the phase table of each phase cell unit is used. At the first time, determine the cell unit of the phase used last time, call the table number included in each phase of the phase, and select the table number with the smallest deviation. ,
The table number is called and fixed when the number of times the table is used is more than once.

  As described above, according to the present invention, when the magnetic pole position is estimated at the start of the PM motor by the method of applying the pulse voltage, the error between the estimated value at the magnetic pole position estimation and the actual magnetic pole position can be further reduced. It is possible.

The block diagram of the cell multiple voltage type inverter control circuit to which this invention is applied. The block diagram of a pulse voltage output command generation part. The flowchart at the time of output cell unit determination. The flowchart at the time of table number selection. The block diagram of a serial multiple inverter. The block diagram of a cell unit (single phase inverter). The current response when applying a pulse voltage is a system diagram. The pulse voltage vector and the generated current vector diagram. The pulse voltage vector diagram to apply. The current difference vector diagram to generate. Explanatory drawing at the time of pulse voltage application. The pulse voltage vector diagram when there is a voltage difference of the output cell unit. The current difference vector figure at the time of pulse voltage vector nonuniformity.

FIG. 1 is a partial view of a cell multiple voltage source inverter control apparatus to which the present invention is applied. 1 is a control unit (CPU) for generating U, V, W phase voltage commands and carrier frequency commands, and 2 is a voltage region. Is output to the carrier phase select (hereinafter referred to as CPS in the carrier phase selection method) control unit 5.
The CPS control unit 5 determines a region of each phase divided by defining a voltage command region and a level in the CPS method based on the phase voltage command.

  Reference numeral 3 denotes a carrier signal generation unit that generates phase signals of 60 degrees and 90 degrees based on a carrier frequency command from the CPU 1 and outputs the phase signals to the rotation control unit 4. In the rotation control unit 4, combinations to be carrier-rotated are defined, and when a combination of gate states occurs, carrier rotation is performed and input to the CPS control unit 5. The CPS control unit 5 inputs a signal obtained by comparing each carrier signal with a voltage command, generates an on / off signal, and inputs the signal to the output cell determination unit 6. 7 is a dead time generator.

FIG. 2 is a generation diagram of the phase voltage commands Vu ^* , Vv ^* , and Vw ^* in the CPU 1. The pulse voltage amplitude command and the pulse generation phase command are input to the cosine signal generation unit 11 and the sine signal generation unit 12, respectively. The voltage amplitude commands Vd ^* and Vq ^* are generated and input to the reverse rotation coordinate conversion unit 13 and input to the two-phase / three-phase converter 14 together with the rotation coordinate reference phase of θ = 0 input via the time integrator 15. The pulse voltage command (= phase voltage command Vu ^* , Vv ^* , Vw ^* ) is generated when input.

  As shown in FIG. 2, when applying a pulse voltage, a pulse amplitude command and a phase command are given, and a rotation coordinate reference phase 0 is given to generate a pulse voltage command. The number of output cell units is determined by the amplitude of the pulse voltage and the pulse generation phase. Here, for the sake of simplicity, let us consider a case where the pulse generation phase command is 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °.

  First, the output voltage command for each phase and the number of stages of output cell units will be described. The magnitude of the output voltage command and the number of stages of the output cell unit are as shown in Table 1. Here, the magnitude of the output voltage command is shown as a ratio of the rated output voltage absolute value and the output voltage command absolute value. Further, when the output voltage command absolute value is the rated output voltage absolute value, it is set to 100%.

  As shown in Table 1, when the number of cell unit connection stages is three in series, the magnitude of the output voltage can be divided into three stages, and the number of output stages for each phase can be determined by the magnitude of the output voltage. Is decided.

  Next, the relationship between the amplitude of the pulse voltage, the phase command, and the output voltage command of each phase will be described. Table 2 shows this relationship. Here, the amplitude of the pulse voltage is 100%. The meaning of 100% of the amplitude is a ratio of the magnitude of the pulse voltage command to the rated output voltage.

In the case of Table 2, the number of output stages of each cell is 2 or 3 from Table 1. In this case, if the number of stages is 3, all the cell units are output, so there is no need to specify the output cell unit. Consider the case of two stages.
In order to simplify the fixing of the output cell unit, a table of the number of output cell stages and the output cell unit is provided for each phase. Table 3 shows a V-phase output cell immobilization table. Here, 1 and 0 of the cells V1, V2, and V3 indicate a state where 1 is an output cell unit and a state where 0 is not an output cell unit.

Next, an output cell unit determination method will be described. This determination is performed by the output cell determination unit 6.
As described above, the number of output cell units is determined by the amplitude of the pulse voltage and the pulse generation phase. First, the number of stages of the output cell unit is determined according to the magnitude of the output voltage of each phase. When the number of output cell units is determined, the cell unit to be used during magnetic pole position estimation is determined from the table in Table 3. In this example, the inverter is a configuration of three cell units for each phase, and the DC voltage of each cell unit is measured. Table numbers 1 to 3 in Table 4 are created. At the same time, the deviation ΔV of the degree of variation is obtained. The deviation is obtained by taking the absolute value of the largest voltage difference with respect to the average.

The deviation ΔV is obtained from the detected DC voltage of each cell unit by the following calculation.
U1 = 100.1 V1 = 100.3 W1 = 100.5 → 300.9
U2 = 110.0 V2 = 110.3 W3 = 110.6 → 330.9
U3 = 120.2 V3 = 120.3 W3 = 120.4 → 360.9
Then,
Deviation of table number 4: Average value (300.9 + 330.9) /6=105.3 The largest difference ΔV = 110.6−105.3 = 5.3
Deviation of table number 5: average value (300.9 + 360.9) /6=110.3 The largest difference △ V = 110.3−100.1 = 10.2
Deviation of table number 6: Average value (330.9 + 360.9) /6=115.3 The largest difference ΔV = 115.3−110.1 = 5.2
Although the deviation ΔV wave voltage value is described, evaluation may be made in% using the average value as the denominator.

There are only three types of table numbers 4 to 6 in Table 4, and in each table, the deviation is obtained by taking the absolute value of the largest voltage difference with respect to the average value. As an example, when the number of output cell units is one, the table number to be selected is selected as 3 (ΔV = 0.1) having the smallest deviation. When the number of output cell units is two, table number 6 (ΔV = 5.2) having the smallest deviation is selected. Thereby, the nonuniformity of the pulse voltage when the number of stages of the output cell unit is two is improved.
When the selection of the table number is completed, the table number that has been used once is stored, and for the same number of output cell stages, the stored table number is always used. In this way, the output cell during application of the pulse voltage is fixed.

FIG. 3 is a flowchart of output cell unit determination in the output cell determination unit 6 based on the above description.
In step S1, based on the amplitude of the pulse voltage and the pulse generation phase set by the CPU 1, in step S2, the number of output cell units is determined based on the magnitude of each phase output voltage.

  In step S3, from the combination table of output cell units, the table numbers with the smallest deviation ΔV are selected for the first and second stages, that is, number 3 and number 6, and the table number 7 for use of all output cell units is selected for the third stage. call. In S4, the output cell unit is fixed, and in S5, the table number having the smallest deviation ΔV is stored, and this stored table number is always used for generating the gate signal.

FIG. 4 shows a flowchart when the table number is selected in step S3.
In step S31, when the number of stages of the output cell unit is determined in S2, the number of times of using the table of the number 1 or 2 of the output cell unit is determined, and in the first time, the process proceeds to S32 and the output cell unit used last time is determined. Is done. If the output cell unit is V1, for example, a table number including V1 of V phase is called. Similarly, in the case of V2, in the case of V2 and V3, the table number including V3 is called and the process proceeds to the fixed table processing of the output cell unit.
On the other hand, when the number of use tables is the second or more in S31, the table number of the number of output cell unit stages is called and the process proceeds to the fixed table processing of the output cell unit.
As described above, which cell unit is to be operated can be determined.

  When the set voltage is 25%, one cell unit for each phase is used, but the one close to the DC voltage Vdc is selected. The voltage may be adjusted by PWM control as shown in FIG. In this case, although the voltage pulse application period width may be different, the measured value of each phase can be used by adopting the time with the shortest time width.

As described above, the present invention arranges the measured DC voltage of each cell unit in ascending order for each phase in the method of applying a pulse voltage when estimating the magnetic pole position at the start of the PM motor. The groups for each phase cell unit are set as shown in Table Nos. 1 to 3 in Table 4. As for the setting of two cell units for each phase, the groups that can be combined from the group at the time of one cell unit described above are set as shown in table numbers 4 to 6 in Table 3-1.
Next, for the group determined as described above, the voltage variation deviation ΔV is obtained to extract the minimum deviation group, and the minimum deviation group is used as the estimated value at the time of estimating the magnetic pole position. Thereby, the error between the estimated value at the time of estimating the magnetic pole position and the actual magnetic pole position can be further reduced.

1. Control unit (CPU)
2 ... Voltage region determination unit 3 ... Carrier signal generation unit 4 ... Rotation control unit 5 ... Carrier phase select control unit (CPS control unit)
6 ... Output cell determination unit 7 ... Dead time generation unit

Claims (4)

The PM motor is controlled by a three-phase inverter in which a plurality of cell units are connected in series, and an output cell determination unit is obtained from a signal input via the CPS control unit using a CPS control method (carrier phase select control method). In the method of selecting a switching pattern of the cell unit and outputting a selection signal to the gate and applying a pulse voltage to the PM motor to estimate the magnetic pole position when starting the PM motor.
The output cell determination unit
The DC voltage of each cell unit determined by determining the number of stages of each phase cell unit connected in series from the amplitude and pulse phase of the pulse voltage is arranged in ascending order for each phase, and each phase cell unit is arranged for each arranged order. Set the hour group,
Set a group in which each phase cell unit can be combined from two groups in one phase.
Extract the minimum deviation group by obtaining the voltage deviation deviation for each of the set phase cell unit groups for each of the 1 and 2 groups,
A magnetic pole position estimation method for a cell multiple voltage source inverter, wherein the extracted minimum deviation group is used as an estimated value of a magnetic pole position at the time of magnetic pole position estimation. 2. The cell multiple voltage source inverter according to claim 1, wherein the estimated value of the extracted magnetic pole position is stored in an immobilization table of an output cell unit, and the output cell unit during application of a pulse voltage is immobilized. Magnetic pole position estimation method. In the immobilization table of the output cell unit,
3. A method of estimating a magnetic pole position of a cell multiple voltage source inverter according to claim 2, wherein a table number corresponding to the number of stages of each phase cell unit is attached, and the magnetic pole position is estimated by selecting the attached table number. . Immobilization of the output cell unit to the immobilization table is as follows:
Determine the number of times the phase table of each phase cell unit is used. At the first time, determine the cell unit of the phase used last time, call the table number included in each phase of the phase, and select the table number with the smallest deviation. ,
4. The method for estimating a magnetic pole position of a cell multiple voltage type inverter according to claim 2, wherein when the number of times the table is used is equal to or more than twice, a table number is called and fixed.

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