TWI697194B - Permanent magnet motor rotor position detecting device and method thereof - Google Patents

Abstract

A permanent magnet motor rotor position detecting device and method thereof, comprising: inputting a first forward test voltage to a permanent magnet motor, corresponding to generating a first forward test current; generating a first reverse test current to the permanent magnet motor according to the first forward test current, recording a first current zero crossing time point; after the first current zero crossing time point, inputting a second forward test voltage to the permanent magnet motor, corresponding to generating a second forward test current; generating a second reverse test current to the permanent magnet motor according to the second forward test current; detecting a total current on the permanent magnet motor to obtain a plurality of total current peaks; obtaining a rotor position phase difference according to the total current peaks.

Description

Permanent magnet motor rotor position detection device and method

This case relates to the field of permanent magnet motor control, in particular to a permanent magnet motor rotor position detection device and method.

Due to the advantages of high performance and low cost, permanent magnet motors are widely used in various fields. The permanent magnet motor includes a rotor and a stator. The permanent magnet motor generates a magnetic field through the stator to attract or repel the rotor, and further generates motor torque through the rotation of the rotor to achieve the output function. Among them, in order to accurately control the permanent magnet motor to achieve the desired output power, the position of the rotor needs to be measured.

At present, permanent magnet motors are usually equipped with an encoder to accurately measure the position of the rotor, but the encoder can only measure the relative position of the rotor, so there is still no way to measure the absolute position of the rotor (that is, the position when it is stopped) help. Therefore, in order to measure the position of the rotor when it is stopped, some permanent magnet motors are more equipped with sensors for measurement, but the cost is relatively increased. On the contrary, although the sensorless permanent magnet motor has the advantage of low cost, it is not easy to accurately measure the rotor position of the permanent magnet motor. If the sensorless permanent magnet motor cannot accurately detect the rotor position, the starting torque of the motor may be reduced or a temporary reversal may occur during start-up, and the motor itself or the motor-driven device may be damaged.

In view of this, this case proposes a permanent magnet motor rotor position detection device and method.

A rotor position detection method for a permanent magnet motor includes: a first voltage input step, inputting a first forward test voltage to the permanent magnet motor, correspondingly generating a first forward test current; a first reverse current input step, based on the A forward test current, generating the first reverse test current to the permanent magnet motor, recording the first current zero-crossing time point; the second voltage input step, after the first current zero-crossing time point, input the second forward direction The test voltage is applied to the permanent magnet motor, corresponding to the second forward test current, wherein the first positive phase corresponding to the first positive test current differs from the second positive phase corresponding to the second positive test current by 180 degrees; In the current input step, according to the second forward test current, a second reverse test current is generated to the permanent magnet motor, and the zero-crossing time point of the second current is recorded, wherein the first negative phase corresponding to the first reverse test current and the first The second negative phase corresponding to the second reverse test current differs by 180 degrees; the current detection step detects the total current on the permanent magnet motor to obtain multiple total current peaks; and the phase difference acquisition step obtains the rotor based on the total current peak The position is out of phase.

According to some embodiments, a permanent magnet motor rotor position detection device includes a voltage input unit, a reverse current input unit, a current detection unit, and a processor. The processor is coupled to the voltage input unit, the reverse current input unit, and the current detection unit. The voltage input unit is used to input multiple forward test voltages to the permanent magnet motor in a one-to-one manner according to multiple current zero-crossing time points, and correspondingly generate multiple forward test currents. The reverse current input unit is used to generate a negative test current to the permanent magnet motor according to the positive test current, respectively. The current detection unit detects the total current on the permanent magnet motor to obtain multiple total current peaks and current zero crossing points. The processor is used to obtain the rotor position phase difference according to the total current peak value.

In summary, the permanent magnet motor rotor position detection device and method of some embodiments in this case can obtain the rotor current phase difference by inputting forward test voltages of different phases to the permanent magnet motor and detecting the peak value of the total current .

10: Permanent magnet motor rotor position detection device

100: voltage input unit

200: reverse current input unit

300: current detection unit

400: processor

500: storage unit

20: Permanent magnet motor

30: rotor

32: N pole

34: S pole

40: stator

50: control device

D _d : d direction

D _q : q direction

L _U : coil

L _V : coil

L _W : coil

V _U : U phase voltage

V _V : V phase voltage

V _W : W phase voltage

I: total current

T: time

T2: Second working time

S100-S400: steps

FIG. 1 is a schematic diagram of a permanent magnet motor according to some embodiments of this case.

FIG. 2 is a schematic diagram of a permanent magnet motor according to some embodiments of this case.

FIG. 3 is a schematic diagram of a permanent magnet motor rotor position detection device according to some embodiments of the present invention.

FIG. 4 illustrates a schematic diagram of a permanent magnet motor rotor position detection method according to some embodiments of the present invention.

FIG. 5 is a schematic diagram of current zero-crossing time points in some embodiments of the present case.

FIG. 6 is a graph showing the relationship between the measurement phase of the sensor and the rotor position phase difference in a comparative embodiment of this case.

7 is a diagram illustrating the relationship between the measurement phase of the sensor and the phase difference of the rotor position according to an embodiment of the present invention.

FIG. 8 shows a schematic diagram of the total current of a comparative example of this case.

FIG. 9 is a schematic diagram of the total current according to an embodiment of this case.

1 and 2 are schematic diagrams of permanent magnet motors 20 according to some embodiments of the present invention. Please refer to FIGS. 1 and 2 simultaneously. In some embodiments, the permanent magnet motor 20 includes a rotor 30, a stator 40 and a control device 50. The rotor 30 has a pair of magnetic poles, respectively N pole 32 and S pole 34, to form a rotor magnetic field in the permanent magnet motor 20. The stator 40 includes a coil L _U , a coil L _V and a coil L _W , and the coil L _U , the coil L _V and the coil L _W differ from each other by 120 degrees. Coil L _{U is} coupled to U phase voltage V _U , coil L _{V is} coupled to V phase voltage V _V , and coil L _{W is} coupled to W phase voltage V _W. The control device 50 is used to control the U-phase voltage V _U , the V-phase voltage V _V and the W-phase voltage V _w , that is, the input current in the coil L _U , the coil L _V and the coil L _W can be controlled. The stator magnetic field can be formed in the permanent magnet motor 20 due to the input currents in the electro-magnetic coil L _U , the coil L _V and the coil L _W. Since the stator magnetic field and the rotor magnetic field can attract or repel each other, the rotor 30 can be controlled to rotate by controlling the U-phase voltage V _U , the V-phase voltage V _V and the W-phase voltage V _w . For ease of explanation, the simplified “input current in coil L _U , coil L _V and coil L _W” is the input current of a certain phase, so the input currents of different phases correspond to different U phase voltages V _U and V phase voltages V _V And W phase voltage V _w combination.

As mentioned above, the permanent magnet motor 20 includes the d direction D _d and the q direction D _q , the d direction D _d is the horizontal direction of the rotor 30, the q direction D _q is the vertical direction of the rotor 30, and the d direction D _d and the q direction D _{q are} mutually vertical. Since the input current of the phase corresponding to the d direction D _{d has the} smallest torque on the rotor 30 and the input current of the phase corresponding to the q direction D _{q has the} greatest torque on the rotor 30, the detection of the q direction D _{q of the} permanent magnet motor 20 corresponds to The phase difference between the phase of and the phase of the input current allows the permanent magnet motor 20 to output at maximum torque. For ease of explanation, the phase difference between the phase corresponding to the q direction D _{q of the} permanent magnet motor 20 and the phase of the input current is referred to as “rotor position phase difference” for short.

FIG. 3 is a schematic diagram of a permanent magnet motor rotor position detection device 10 according to some embodiments of the present invention. 3, in some embodiments, the permanent magnet motor rotor position detection device 10 includes a voltage input unit 100, a reverse current input unit 200, a current detection unit 300, a processor 400, and a storage unit 500. The voltage input unit 100, the reverse current input unit 200, the current detection unit 300 and the storage unit 500 are coupled to the processor 400. In some embodiments, the voltage input unit 100, the reverse current input unit 200, and the current detection unit 300 are coupled to the storage unit 500.

Please refer to FIG. 2 and FIG. 3 at the same time. In some embodiments, the permanent magnet motor rotor position detection device 10 can be built into the permanent magnet motor 20 as a control device 50 of the permanent magnet motor 20. On the contrary, in some embodiments, the permanent magnet motor rotor position detection device 10 can be externally connected to the permanent magnet motor 20 and control the control device 50 in the permanent magnet motor 20.

In some embodiments, the voltage input unit 100 is used to input a forward test voltage to the permanent magnet motor 20, or it can be said that the voltage input unit 100 is used to input a forward test current to the permanent magnet motor 20, because when the forward test voltage When applied to the permanent magnet motor 20, a corresponding forward test current is generated. It should be noted that the forward test voltage is a surge voltage. After the surge voltage is applied to the permanent magnet motor 20, the current generated by the surge voltage will oscillate with time and gradually attenuate. Therefore, the forward test current will also oscillate with time and gradually decay.

In some embodiments, the voltage input unit 100 is used to sequentially input multiple forward test voltages to the permanent magnet motor 20, that is, the voltage input unit 100 is used to sequentially input multiple forward test currents to the permanent magnet motor 20. Each forward test current has a current peak value, which is the maximum current value of the forward test current. In addition, each forward test current corresponds to a positive phase, which corresponds to a forward test voltage. According to some embodiments, the permanent magnet motor rotor position detection device 10 detects the rotor position phase difference and needs to input twelve positive test currents corresponding to different phases to the permanent magnet motor 20 through the voltage input unit 100 according to the forward test The sequence of the current input to the permanent magnet motor 20, the twelve positive phases are 0 degrees, 180 degrees, 30 degrees, 210 degrees, 60 degrees, 240 degrees, 90 degrees, 270 degrees, 120 degrees, 300 degrees, 150 Degrees, and 330 degrees.

In some embodiments, the reverse current input unit 200 is used to input a negative test voltage to the permanent magnet motor 20, that is, to input a negative test current to the permanent magnet motor 20. The current detection unit 300 is used to detect the total current I in the permanent magnet motor 20 and obtain the corresponding Peak current. It should be noted that the negative test voltage is a surge voltage. Therefore, the total current I at any time point is the total current generated by the positive test voltage or the negative test voltage received by the permanent magnet motor 20 before this time point.

In some embodiments, the reverse current input unit 200 is used to generate a negative test current according to the positive test current. Specifically, the negative test current and the positive test current generated by the reverse current input unit 200 have a one-to-one relationship. In other words, whenever the voltage input unit 100 inputs the forward test voltage to the permanent magnet motor 20, the reverse current input unit 200 detects the forward test voltage, and then correspondingly inputs the negative test voltage to the permanent magnet motor 20. The negative test voltage is applied to the permanent magnet motor 20 at the same time as the positive test voltage is applied to the permanent magnet motor 20, that is, the negative test current is used to cancel the corresponding positive test current, so that the total current I oscillates The time required for attenuation is shortened. Since the decay time of the oscillation of the total current I is shortened, the rotor 30 will not rotate due to the forward test current causing measurement error of the rotor position phase difference. According to some embodiments, after the input of the positive test voltage stops, the input of the negative test voltage does not start until after the first working time. According to some embodiments, the positive test voltage is 41 volts (V) for 3/8000 seconds of surge voltage, and the negative test voltage is -41 volts (V) for 3/8000 seconds of surge voltage, the first The working time is 3/8000 seconds, that is, the time difference between the stop input of the positive test voltage and the start input of the negative test voltage is 3/8000 seconds.

In some embodiments, the current detection unit 300 is used to obtain a current zero crossing point. The voltage input unit 100 is used to input the forward test voltage to the permanent magnet motor 20 in a one-to-one manner according to the current zero crossing time point. Specifically, the current zero crossing time point is the time point when the total current I crosses the "zero" current value, especially after the negative test voltage is applied to the permanent magnet motor 20, the total current I crosses for the first time. Time point of "zero" current value. So each forward test voltage and its The corresponding negative test voltage will generate a current zero-crossing time point, and this current zero-crossing time point is the time point when the voltage input unit 100 inputs the next positive test voltage to the permanent magnet motor 20. Therefore, the voltage input unit 100 controls the time to input the forward test voltage. When the total current I oscillation generated by the previous forward test voltage decays to a negligible level, the voltage input unit 100 inputs the next forward test voltage, so that each A forward test current will not interfere with each other to reduce the measurement error of the rotor position phase difference. According to some embodiments, the time point when the negative test voltage stops inputting is earlier than the current zero-crossing time point, and the time point when the negative test voltage stops inputting and the current zero-crossing time point differ by a second working time T2. According to some embodiments, since the forward test currents are almost reversed and the phase difference is 180 degrees or 150 degrees, even if the total current I still has the oscillation caused by the previous forward test voltage, it will be input by the next input. The positive test voltage is overwritten and ignored. It should be noted that at the beginning of the test, because the initial value of the total current I is zero, the first forward test voltage input by the voltage input unit 100 does not need to be input to the permanent magnet motor 20 according to the current zero crossing time . According to some embodiments, the positive phase of the first positive test voltage is 0 degrees.

In some embodiments, the processor 400 is used to obtain the rotor position phase difference according to the total current peak value. Specifically, the processor 400 obtains the phase corresponding to each forward test current from the voltage input unit 100, and the processor 400 obtains the total current peak corresponding to each forward test current from the current detection unit 300. Since each total current peak has a cosine function relationship with the phase of its corresponding forward test current, the processor 400 can calculate and obtain the rotor by two or more different phases of the forward test current and the corresponding total current peak The position is out of phase. And as the detected phases are more and more average, the rotor position phase difference obtained by the processor 400 is more accurate. According to some embodiments, the processor 400 is used to control the voltage input unit 100 to output The positive phase of the forward test current into the permanent magnet motor 20, that is, the processor 400 itself has information on the positive phase corresponding to each forward test current.

其中，θ為轉子位置相位差，x為正相位，y為總電流峰值。 In some embodiments, the processor 400 obtains the rotor position phase difference according to the total current peak value and the positive phase according to the phase difference formula. The phase difference formula is:

Where θ is the phase difference of the rotor position, x is the positive phase, and y is the peak value of the total current.

。 According to some embodiments, when the forward test current is at a phase of 0 degrees, the peak value of the total current is b. When the forward test current is 90 degrees in phase, the peak value of the total current is a. According to the phase difference formula, obtain the rotor position phase difference

.

In some embodiments, the storage unit 500 is used to store a phase-to-peak current relationship table. In addition, the processor 400 uses a K-nearest neighbor algorithm (K-nearest neighbor) to look up the table to obtain the rotor position phase difference according to the total current peak value, the positive phase, and the relationship between the phase and the peak current table.

In some embodiments, the processor 400 converges the total current I in the permanent magnet motor 20 with proportional control (P control) to reduce the oscillation decay time of the total current I and further reduce each forward test voltage to the next forward test The effect of voltage. In some embodiments, the processor 400 converges the total current I in the permanent magnet motor 20 with proportional-integral-derivative control (PID control) to reduce the time when the total current I oscillates.

In some embodiments, the voltage input unit 100, the reverse current input unit 200, the current detection unit 300, and the processor 400 can each be implemented in a single circuit, or integrated in the same circuit. In some embodiments, the voltage input unit 100, the reverse current input unit 200, the current The detection unit 300 and the processor 400 can be integrated into a single-chip microcontroller, but this case is not limited to this.

FIG. 4 illustrates a schematic diagram of a permanent magnet motor rotor position detection method according to some embodiments of the present invention. Please refer to Figure 3 and Figure 4 at the same time. In some embodiments, the permanent magnet motor rotor position detection method includes the following steps: a first voltage input step (step S100); a first reverse current input step (step S150); a second voltage input step (step S200); Two reverse current input steps (step S250); current detection step (step S300); and phase difference obtaining step (step S400).

The first voltage input step (step S100) includes: inputting a first forward test voltage to the permanent magnet motor 20, and correspondingly generating a first forward test current. Specifically, when the permanent magnet motor rotor position detection device 10 starts to detect the rotor position phase difference of the rotor 30, the voltage input unit 100 inputs the first forward test voltage to the permanent magnet motor 20, that is, the voltage input unit 100 inputs The first forward test current is to the permanent magnet motor 20.

The first reverse current input step (step S150) includes: generating a first reverse test current to the permanent magnet motor 20 according to the first forward test current, and recording the zero-crossing time point of the first current. Specifically, when the reverse current input unit 200 detects that the voltage input unit 100 outputs the first forward test voltage, the reverse current input unit 200 generates the first reverse test voltage corresponding to the first forward test voltage to the permanent magnet motor 20, that is, the reverse current input unit 200 generates the first reverse test current to the permanent magnet motor 20. According to some embodiments, when the voltage input unit 100 emits a forward test voltage, a corresponding test signal is also sent to the reverse current input unit 200 to drive the reverse current input unit 200 to output a negative test voltage corresponding to the positive test voltage .

The second voltage input step (step S200) includes: after the first current zero crossing time point, input a second forward test voltage to the permanent magnet motor 20, correspondingly generating a second forward test current, of which the second forward direction The second positive phase corresponding to the test current differs from the first positive phase corresponding to the first positive test current by 180 degrees. Specifically, due to the effects of the first positive test voltage and the first negative test voltage, the total current I obtained by the current detection unit 300 will oscillate and decay to zero. After the input of the first negative test voltage ends, the total current I The time point of the first zero crossing current value is the time point of the first current zero crossing. When the current detection unit 300 detects the first current zero crossing time point, the voltage input unit 100 responds to input the second forward test voltage to the permanent magnet motor 20. According to some embodiments, the first positive phase is 0 degrees and the second positive phase is 180 degrees. According to some embodiments, when the current detection unit 300 detects a zero-crossing time point, the current detection unit 300 can send a driving signal to the voltage input unit 100 to drive the voltage input unit 100 to input a positive corresponding to the zero-crossing time point To the test voltage to the permanent magnet motor 20.

The second reverse current input step (step S250) includes: generating a second reverse test current to the permanent magnet motor 20 according to the second forward test current, and recording the second current zero-crossing time point, wherein the second reverse test The second negative phase corresponding to the current differs from the first negative phase corresponding to the first reverse test current by 180 degrees. Specifically, when the reverse current input unit 200 detects that the voltage input unit 100 outputs the second forward test voltage, the reverse current input unit 200 generates a second reverse test voltage corresponding to the second forward test voltage to the permanent magnet motor 20, that is, the reverse current input unit 200 generates a second reverse test current to the permanent magnet motor 20.

The current detection step (step S300) includes: detecting the total current I on the permanent magnet motor 20 to obtain a plurality of total current peaks. Specifically, the current detection unit 300 detects the total current I of the permanent magnet motor 20 and based on each forward test voltage (for example, the first forward test voltage and the first Two forward test voltages) to obtain the corresponding total current peak.

The phase difference obtaining step (step S400) includes obtaining the rotor position phase difference according to the total current peak value. Specifically, according to the peak value of the total current detected by the current detection unit 300 and the positive phase of the positive test current of the permanent magnet motor 20 that the processor 400 controls the voltage input unit 100 to input, the processor 400 can calculate the rotor position phase difference. The processor 400 can look up the table according to the phase difference formula or the K-nearest neighbor algorithm to determine the phase difference of the rotor position, as described above.

In some embodiments, the permanent magnet motor rotor position detection method further includes a third voltage input step, a third reverse current input step, a fourth voltage input step, and a fourth reverse current input step. And the third voltage input step, the third reverse current input step, the fourth voltage input step, and the fourth reverse current input step are performed at the second reverse current input step (step S250) and the current detection step (Step S300).

The third voltage input step includes: inputting a third forward test voltage to the permanent magnet motor 20, and correspondingly generating a third forward test current. Similarly, after the second current zero crossing time point, the voltage input unit 100 inputs the third forward test voltage to the permanent magnet motor 20.

The third reverse current input step includes: generating a third reverse test current to the permanent magnet motor 20 according to the third forward test current, and recording the time point of the zero crossing of the third current. Similarly, when the reverse current input unit 200 detects that the voltage input unit 100 outputs a third forward test voltage, the reverse current input unit 200 generates a third reverse test voltage corresponding to the third forward test voltage to the permanent magnet motor 20 That is, the reverse current input unit 200 generates a third reverse test current to the permanent magnet motor 20.

The fourth voltage input step includes: after the third current zero crossing time point, input a fourth forward test voltage to the permanent magnet motor 20, correspondingly generating a fourth forward test current, wherein The fourth positive phase corresponding to the fourth positive test current differs from the third positive phase corresponding to the third positive test current by 180 degrees. According to some embodiments, the third positive phase is 90 degrees and the fourth positive phase is 270 degrees. According to some embodiments, the third positive phase is 30 degrees and the fourth positive phase is 210 degrees.

The fourth reverse current input step includes: generating a fourth reverse test current to the permanent magnet motor 20 according to the fourth forward test current, and recording the zero-crossing time point of the fourth current, wherein the third reverse test current corresponds to the first The three negative phases differ from the fourth negative phase corresponding to the fourth reverse test current by 180 degrees.

In some embodiments, the permanent magnet motor rotor position detection method tests twelve sets of forward test voltages for the permanent magnet motor 20 respectively, that is, the voltage input unit 100 inputs twelve sets of positive test currents of different positive phases to the permanent magnet Motor 20. Among them, according to the order in which the voltage input unit 100 inputs the forward test current to the permanent magnet motor 20, the twelve different sets of positive phases are 0 degrees, 180 degrees, 30 degrees, 210 degrees, 60 degrees, 240 degrees, and 90 degrees, respectively. , 270 degrees, 120 degrees, 300 degrees, 150 degrees, 330 degrees. And each set of forward test voltage corresponds to a voltage input step and a reverse current input step. After the twelve sets of forward test voltages are input to the permanent magnet motor 20 in sequence, the current detection unit 300 detects the total current peak corresponding to each forward test voltage according to the current detection step (step S300). The phase difference obtaining step (step S400) obtains the rotor position phase difference. According to some embodiments, 0 degrees, 180 degrees, 30 degrees, and 210 degrees correspond to the first to fourth voltage input steps and the first to fourth reverse current input steps, respectively. 60 degrees, 240 degrees, 90 degrees, 270 degrees, 120 degrees, 300 degrees, 150 degrees, and 330 degrees correspond to the fifth to twelfth voltage input steps and the fifth to twelfth reverse current input steps, respectively.

FIG. 5 is a schematic diagram of current zero-crossing time points in some embodiments of the present case. In some embodiments, please refer to FIG. 5, the X axis is the time T, and the Y axis is the total current I, when the total current I passes After the time point of the total current peak, a negative test voltage is applied to the permanent magnet motor 20 to reduce the oscillation decay time of the total current I. And the current zero crossing time point is the time point at which the total current I crosses the “zero” current value for the first time after the negative test voltage is applied to the permanent magnet motor 20 after the end. The time point at which the input of the negative test voltage stops and the time point at which the current crosses zero are different by the second working time T2.

FIG. 6 is a graph showing the relationship between the measurement phase of the sensor and the rotor position phase difference in a comparative embodiment of this case. 7 is a diagram illustrating the relationship between the measurement phase of the sensor and the phase difference of the rotor position according to an embodiment of the present invention. Among them, the X axis in FIGS. 6 and 7 is the measurement phase of the sensor, and the Y axis is the rotor position phase difference. Referring to FIG. 6, in a comparative embodiment, the permanent magnet motor 20 is equipped with a conventional sensor, and the permanent magnet motor rotor position detection method is not used to detect the rotor position phase difference. Referring to FIG. 7, in one embodiment, the permanent magnet motor 20 is equipped with a conventional sensor, and uses a permanent magnet motor rotor position detection method to detect a phase difference from the rotor position. It can be seen from comparing FIGS. 6 and 7 that the relationship between the phase difference of the rotor position detected by the rotor position detection method of the permanent magnet motor and the measurement phase of the conventional sensor is close to an ideal linear relationship, so FIG. 7 The point of almost converges on the line of the linear relationship (dashed line in FIG. 7), that is, the rotor position phase difference measured by the rotor position detection method of the permanent magnet motor has less measurement error. On the contrary, the relationship between the rotor position phase difference detected by the rotor position detection method of the permanent magnet motor and the measurement phase of the conventional sensor is more divergent, and the points in FIG. 6 do not converge on the line of linear relationship ( On the dotted line in Fig. 6, that is, the error of the rotor position phase difference measurement is large.

FIG. 8 shows a schematic diagram of the total current I of a comparative example of this case. FIG. 9 is a schematic diagram of the total current I according to an embodiment of the present case. Please refer to FIGS. 8 and 9. The X axis is time T, and the Y axis is total current I. Comparing FIG. 8 and FIG. 9, in the process of detecting the rotor position phase difference of the rotor position detection method of the permanent magnet motor, the oscillation attenuation time of the total current I is shorter. In contrast, no permanent magnet motor is used In the sub-position detection method, the oscillation of the total current I decays for a longer time. Therefore, the rotor position detection method of the permanent magnet motor can reduce the possibility of the rotor 30 rotating due to the total current I, and reduce the measurement error of the rotor position phase difference. According to a comparative embodiment, without using the permanent magnet motor rotor position detection method, the oscillation of the total current I converges to a time period suitable for the next forward test voltage input of 100/8000 seconds. According to an embodiment, using a permanent magnet motor rotor position detection method, the oscillation of the total current I converges to a time period suitable for the next forward test voltage input of 18/8000 seconds.

Please continue to refer to FIG. 2 and FIG. 3. As mentioned above, in some embodiments, the permanent magnet motor rotor position detection device 10 can be built into the permanent magnet motor 20 as the control device 50 of the permanent magnet motor 20. The magnetic motor 20 can achieve the function of detecting the rotor position (ie, the rotor position phase difference) without additional sensors. In some embodiments, the permanent magnet motor rotor position detection device 10 can be externally connected to the permanent magnet motor 20, and the permanent magnet motor rotor position detection device 10 controls the control device 50 in the permanent magnet motor 20 to achieve rotor position detection Function.

In summary, the permanent magnet motor rotor position detection device and method of some embodiments in this case can obtain the rotor current phase difference by inputting forward test voltages of different phases to the permanent magnet motor and detecting the peak value of the total current . In some embodiments, when the permanent magnet motor rotor position detection device inputs the forward test current to the permanent magnet motor, the corresponding reverse test current can be input to the permanent magnet motor in real time. Therefore, the oscillation convergence time of the total current can be reduced, and at the same time the rotor will not rotate because of the forward test voltage, thus reducing the measurement error of the rotor position phase difference.

10: Permanent magnet motor rotor position detection device

20: Permanent magnet motor

100: voltage input unit

200: reverse current input unit

300: current detection unit

400: processor

500: storage unit

Claims (10)

A permanent magnet motor rotor position detection method includes: a first voltage input step, inputting a first positive three-phase test voltage to a permanent magnet motor, correspondingly generating a first positive three-phase test current; A first reverse current input step, based on the first forward three-phase test current, generates a first reverse three-phase test current to offset the first forward three-phase test current to the permanent Magnetic motor, record a first current zero crossing time point; a second voltage input step, after the first current zero crossing time point, input a second positive three-phase test voltage to the permanent magnet motor , Corresponding to a second positive three-phase test current, wherein a first positive phase corresponding to the first positive three-phase test current corresponds to a second positive phase corresponding to the second positive three-phase test current 180 degrees out of phase; a second reverse current input step, based on the second forward three-phase test current, generates a second reverse three-phase test used to offset the second forward three-phase test current Current to the permanent magnet motor, recording a second current zero crossing time point, wherein a first negative phase corresponding to the first reverse three-phase test current and a second negative phase corresponding to the second reverse three-phase test current The second negative phase differs by 180 degrees; a current detection step to detect a total current on the permanent magnet motor to obtain a plurality of total current peaks; and a phase difference obtaining step to obtain a rotor based on the total current peaks The position is out of phase. The method for detecting the rotor position of a permanent magnet motor as described in claim 1 further includes: A third voltage input step, inputting a third forward three-phase test voltage to the permanent magnet motor, correspondingly generating a third forward three-phase test current; a third reverse current input step, based on the third Three forward three-phase test currents generate a third reverse three-phase test current to offset the third forward three-phase test current to the permanent magnet motor, and record a third current zero crossing time A fourth voltage input step, after the third current zero crossing time point, input a fourth forward three-phase test voltage to the permanent magnet motor, corresponding to a fourth forward three-phase test Current, wherein a third positive phase corresponding to the third positive three-phase test current differs from a fourth positive phase corresponding to the fourth positive three-phase test current by 180 degrees; and a fourth reverse current input Step, according to the fourth forward three-phase test current, generate a fourth reverse three-phase test current to offset the fourth forward three-phase test current to the permanent magnet motor, record a fourth The current zero-crossing time point, wherein a third negative phase corresponding to the third reverse three-phase test current and a fourth negative phase corresponding to the fourth reverse three-phase test current are different by 180 degrees. The permanent magnet motor rotor position detection method according to claim 2, wherein the first positive phase is 0 degrees, the second positive phase is 180 degrees, the third positive phase is 90 degrees, and the fourth positive phase Is 270 degrees. The permanent magnet motor rotor position detection method according to claim 3, wherein the step of obtaining the phase difference further includes: according to the total current peaks, the first positive phase, the second positive phase, the third positive phase, And the fourth positive phase, the rotor position phase difference is obtained by a phase difference formula, the phase difference formula is:

Where θ is the phase difference of the rotor position, x is the first positive phase, the second positive phase, the third positive phase, and the fourth positive phase, and y is the total current peaks. The permanent magnet motor rotor position detection method according to claim 3, wherein the step of obtaining the phase difference further includes: according to the total current peaks, the first positive phase, the second positive phase, the third positive phase, The fourth positive phase and a relation table between the phase and the peak current are obtained by a K-nearest neighbor algorithm (K-nearest neighbor). A permanent magnet motor rotor position detection device includes: a voltage input unit for inputting a plurality of positive three-phase test voltages to a permanent magnet motor in a one-to-one manner according to a plurality of current zero-crossing time points, Correspondingly generate multiple forward three-phase test currents, of which the phase difference between any two forward three-phase test currents generated is 180 degrees or 150 degrees; a reverse current input unit is used to The forward three-phase test current generates a reverse three-phase test current to the permanent magnet motor, respectively, and the reverse three-phase test current is used to offset the corresponding forward three-phase test current; a current A detection unit, which detects a total current on the permanent magnet motor to obtain a plurality of total current peaks and zero-crossing time points of the currents; and a processor, coupled to the voltage input unit and the reverse current input The unit and the current detection unit, the processor is used to obtain a rotor position phase difference according to the total current peaks. The permanent magnet motor rotor position detection device according to claim 6, wherein the forward three-phase test currents correspond to the total current peaks in a one-to-one manner, and the forward three-phase test currents are The one-to-one approach corresponds to the current zero-crossing time points. The permanent magnet motor rotor position detection device according to claim 6, wherein the positive three-phase test currents respectively correspond to a positive phase, according to the order in which the positive three-phase test currents are input to the permanent magnet motor The positive phases are 0 degrees, 180 degrees, 30 degrees, 210 degrees, 60 degrees, 240 degrees, 90 degrees, 270 degrees, 120 degrees, 300 degrees, 150 degrees, and 330 degrees in sequence. The permanent magnet motor rotor position detection device according to claim 8, wherein the processor obtains the rotor position phase difference according to the total current peak value and the positive phases with a phase difference formula, the phase difference formula is:

Where θ is the phase difference of the rotor position, x is the positive phases, and y is the total current peaks. As described in claim 8, the rotor position detection device of the permanent magnet motor further includes a storage unit for storing a phase-to-peak current relationship table, and the processor is based on the total current peaks, the positive phases, And the relationship table between the phase and the peak current, the rotor position phase difference is obtained by a K-nearest neighbor algorithm (K-nearest neighbor).

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