TW201421892A - Method for the initial position detection of permanent synchronous motor - Google Patents

Abstract

A method for detecting the initial position of magnetic poles in a permanent synchronous motor is disclosed. The method includes the steps of: applying PWM pulse trains of voltage vector to the phase windings of the permanent synchronous motor, respectively, until the motor's phase currents approach a predetermined current value; measuring discharging currents in the phase windings in a predetermined interval after the PWM pulse trains stop being applied to the motor, or measuring a discharge time in which discharging currents in the phase windings approach the predetermined current value after the PWM pulse trains stop being applied to the motor; and determining the initial position of magnetic poles in the motor according to the measured discharging currents or the measured discharge time.

Description

Magnetic pole initial position detecting method of permanent magnet synchronous motor

The disclosure relates to a method for detecting the initial position of a magnetic pole of a permanent magnet synchronous motor, in particular to a magnetic field of a permanent magnet synchronous motor which adopts a two-phase excitation method and does not require an additional voltage measuring circuit, and can effectively prevent the motor from being reversed at startup. Initial position detection method.

Generally speaking, a permanent magnet synchronous motor is composed of a multi-phase winding and a permanent magnet, and may be referred to as an internal rotation type and an external rotation type permanent magnet synchronous motor according to a permanent magnet placed on the inner rotor or the outer rotor; The initial position is random and unknown, so it may cause the rotor to reverse when starting, but for the application of electric vehicles, fans, etc., the permanent magnet synchronous motor is not allowed to rotate the magnetic pole during the initial position detection of the magnetic pole and reverse at the start. . Regarding this problem, most of the relevant technical fields are currently solved by adding a Hall sensor or an encoder to the permanent magnet synchronous motor, but the cost is increased, the structure is complicated, and space is occupied, and Hall The sensor or the encoder is easily damaged, and the maintenance cost is high and the purpose of detecting the initial position of the magnetic pole cannot be achieved.

For the public literature, for example, a magnetic pole initial position detecting method is to apply a fixed voltage to a three-phase winding for a fixed period of time to cut away, and measure the time to drop to a set voltage, and the comparison time can estimate the starting angle. Or, for example, a permanent magnet motor starting magnetic pole detecting method, which first determines a PWM pulse width applied to the stator according to the motor parameter, sequentially outputs six voltage vectors to the stator, and calculates a current rise caused by each voltage vector. In between, the rise time is compared to obtain a preliminary rotor position, and then six voltage vectors are repeatedly output to the stator and the rotor position is recalculated. Or a permanent magnet type brushless motor without sensor controlled rotor pole initial interval estimating device and method thereof, the method comprising the steps of: providing a brushless DC motor (BLDCM) comprising a rotor and a certain sub-coil, Wherein, the rotor comprises N and S poles; a low frequency low voltage signal is input to the brushless DC motor by a 120° energization mode, and the flux type of the non-conducting phase coil is used to estimate the brushless DC motor. The initial interval of the rotor.

However, conventionally, in order to detect the initial position of the magnetic pole, the number of voltages applied to the motor winding requires at least twice the number of motor phases, the number of application times is large and time consuming; and the applied voltage is 100% or fixed. The duty cycle (Duty) pulse wave is easy to cause the magnetic pole to rotate during the initial detection of the magnetic pole; and it requires excitation of more than three phases, resulting in an error caused by the dominant discharge current of the unsaturated phase coil; in addition, the conventional measurement voltage is The method is to measure the discharge time by measuring the voltage, or to calculate the charging time by measuring the current, or to determine the induced potential state by measuring the voltage, and an additional voltage measuring circuit is needed.

Accordingly, it is possible to have a magnetic pole initial which can reduce the number of applied voltages, does not cause the magnetic pole to rotate during detection, can improve the excitation measurement error, does not require an additional voltage measurement loop, and can effectively prevent the motor from being reversed at startup. The position detection method is an urgent problem to be solved by those skilled in the related art.

In an embodiment, the present disclosure provides a magnetic pole initial position detecting method for a permanent magnet synchronous motor, which includes the following steps: (a) according to the phase number of the permanent magnet synchronous motor, the relative of the permanent magnet synchronous motor Between the phase windings, the voltage vector pulse wave having the pulse width modulation is repeatedly applied to the permanent magnet synchronous motor until the phase current reaches the same one of the set discharge currents, and then the applied voltage vector is cut off; (b ??? measuring a discharge current of one of the windings after the applied voltage vector is cut off; and (c) determining the permanent magnet according to the measured magnitude of the discharge current of the phase winding The initial position of the magnetic pole of the synchronous motor.

In another embodiment, the present disclosure further provides a magnetic pole initial position detecting method for a permanent magnet synchronous motor, which includes the following steps: (a) according to the phase number of the permanent magnet synchronous motor, the relative of the permanent magnet synchronous motor Between the phase windings, the voltage vector pulse wave having the pulse width modulation is repeatedly applied to the permanent magnet synchronous motor until the phase current reaches the same one of the set discharge currents, and then the applied voltage vector is cut off; (b After measuring the applied voltage vector, measuring the discharge time when the windings reach the same discharge current; and (c) determining the magnetic pole of the permanent magnet synchronous motor according to the measured discharge time when the same discharge current is reached initial position.

In an embodiment, the present disclosure further provides a control flow for detecting the initial position of the magnetic pole, which includes the following steps: first setting a reference value to zero; determining whether the reference value is equal to one of the detected permanent magnet synchronous motors. If the reference value is not equal to the phase number, perform two-phase excitation and current decrement, and record a discharge current or a discharge time; accumulate the reference value by one, change the excitation phase, and then repeatedly determine whether the reference value is Equal to the number of phases, Until the reference value is equal to the phase number; and based on the recorded discharge current or discharge time, the magnetic pole initial position of the permanent magnet synchronous motor is obtained by looking up the table.

The following is a specific technical means for achieving the present disclosure by taking a three-phase permanent magnet synchronous motor as an example. However, the method of the present disclosure is not limited to a three-phase permanent magnet synchronous motor, and the present disclosure can be implemented in a permanent magnet synchronous motor having more than three phases.

Refer to Table 1 below for a table of magnetic pole initial position definitions for a three-phase permanent magnet synchronous motor:

As shown in Table 1, when the initial position of the magnetic pole of the three-phase permanent magnet synchronous motor is "1", it means that the "S" pole of the magnetic pole faces the U-phase winding, and the electrical angle defining this position is 270 degrees. When the initial position of the magnetic pole of the three-phase permanent magnet synchronous motor is "2", it means that the "N" pole of the magnetic pole faces the W-phase winding, and the electrical angle defining this position is 330 degrees. And so on, the other four magnetic pole initial positions of the three-phase permanent magnet synchronous motor are respectively defined as 30 degrees, 90 degrees, 150 degrees, and 210 degrees.

Please refer to the winding excitation method proposed in the first to third figures, wherein the first figure shows that the U-phase winding is the power transmission phase and the V-phase winding is the power receiving phase, and the second figure shows the V-phase winding. The power transmission phase and the W phase winding are the power receiving phases, and the third figure shows that the W phase windings are the power transmitting phase and the U phase windings are the power receiving phases. The disclosure discloses that one of the phase windings is floated as shown in the first to third figures, and only for the excitation of the two-phase winding, in order to avoid the pulse wave of the voltage vector of the permanent magnet synchronous motor being applied with a duty cycle of 100%, And cause the magnetic pole to rotate.

The voltage vector pulse wave applied by the disclosure is listed in the pulse waveguide duty cycle, respectively, one phase winding of the permanent magnet synchronous motor is connected to the positive end of the DC power supply, and the other phase winding is connected to the negative end of the DC power supply, and other phase windings are connected. Then floating; this phase winding connected to the negative end of the DC power supply, the next applied voltage vector pulse is listed in the pulse waveguide duty cycle, is connected to the positive end of the DC power supply, and is not connected to the floating phase The phase winding of the negative end of the DC power supply is alternatively connected to the negative end of the DC power supply. At this time, the other phase windings are floated; the pulse wave with the pulse width modulation voltage vector is repeatedly applied according to the number of phases to the permanent magnet synchronous motor. Winding and measuring the magnitude of the discharge current or the discharge time of the windings to detect the initial position of the magnetic pole of the permanent magnet synchronous motor.

For example, the applied voltage vector pulse is listed in the pulse-wave-on duty cycle. The U-phase winding in the first figure is connected to the positive terminal of the DC power supply +V _DC , and the V-phase winding is connected to the negative terminal of the DC power supply. The winding is floated; when the next applied voltage vector pulse is listed in the pulse-wave-pass duty cycle, as shown in the second figure, the V-phase winding is connected to the positive terminal of the DC power supply +V _DC , and the W-phase winding is connected. To the negative end of the DC power supply, and the U-phase winding is floated; when the voltage is applied to the next applied voltage pulse wave is listed in the pulse-wave-pass duty cycle, as shown in the third figure, the W-phase winding is connected to the DC The positive terminal of the power supply is +V _DC , the U-phase winding is connected to the negative terminal of the DC power supply, and the V-phase winding is floated. In addition, the applied voltage vector pulse duty cycle with pulse width modulation can cause the winding current to rise rapidly, but not enough to cause the permanent magnet synchronous motor to rotate.

Please refer to the embodiment of the duty cycle of the applied voltage vector pulse train and the initial position detection of the magnetic pole as shown in the fourth figure. As shown in the fourth figure, the applied voltage vector pulse wave with the pulse width modulation is listed in the permanent magnet synchronous motor winding until the current reaches a set discharge current i _D , and then the applied voltage vector is cut off; The set voltage is cut off by a set discharge time t1, and the winding discharge current i _{D is} measured to detect the initial position of the magnetic pole of the permanent magnet synchronous motor.

Taking the U-phase winding as the power-transfer phase and the V-phase winding as the power-receiving phase as shown in the first figure, when the applied voltage vector is cut off, the winding discharge current at the discharge time set after one of the cut-off is measured. i _D is i _D-UV , and after the second graph is separated from the applied voltage vector shown in the third graph, the magnitude of the winding discharge current measured at the same time after the cut-off is i _D-VW and i, respectively. _D-WU . By comparing the discharge times i _D-UV , i _D-VW and i _D-WU , and depending on the discharge current, the initial position of the magnetic pole of the permanent magnet synchronous motor can be determined. The method for measuring the magnitude of the discharge current of the windings is to measure the set discharge time after the winding connected to the positive end of the DC power source for each pulse train, the magnitude of the current drop, and compare the current fall amplitudes.

As shown in Tables 2 and 3 below, the results of determining the initial position of the magnetic pole of the permanent magnet synchronous motor are determined based on the maximum discharge current and the minimum discharge current, respectively.

Please refer to the fifth embodiment for the duty cycle of the applied voltage vector pulse train and the magnetic pole initial position detection. As shown in the fifth figure, the applied voltage vector pulse wave with the pulse width modulation is listed in the permanent magnet synchronous motor winding until the current reaches a set discharge current i1, and then the applied voltage vector is cut off; After the applied voltage vector is excised, the discharge time t _D reaching the same discharge current is measured to detect the initial position of the magnetic pole of the permanent magnet synchronous motor.

Taking the U-phase winding as the power-transmitting phase and the V-phase winding as the power-receiving phase as shown in the first figure, when the applied voltage vector is cut off, the discharge time t _D when measuring the same discharge current is t _D-UV Similarly, after the voltage vectors applied in the second and third figures are separated, the discharge time when the measurement reaches the same discharge current is t _D-VW and t _{D-WU , respectively} . By comparing the discharge times t _D-UV , t _D-VW and t _D-WU , and based on the discharge time comparison result, the initial position of the magnetic pole of the permanent magnet synchronous motor can be determined. As shown in Tables 4 and 5 below, the results of determining the initial position of the magnetic pole of the permanent magnet synchronous motor are determined based on the maximum discharge time and the minimum discharge time.

According to the above embodiment, the magnetic pole initial position detecting method of the two permanent magnet synchronous motors can be summarized, and the permanent magnet synchronous motor has a multi-phase winding. One of the methods is based on the magnitude of the discharge current, and includes the following steps: (a) according to the phase number of the permanent magnet synchronous motor, the relative of the permanent magnet synchronous motor Between the phase windings, the voltage vector pulse wave having the pulse width modulation is repeatedly applied to the permanent magnet synchronous motor until the phase current reaches the same one of the set discharge currents, and then the applied voltage vector is cut off; (b ??? measuring a discharge current of one of the windings after the applied voltage vector is cut off; and (c) determining the permanent magnet according to the measured magnitude of the discharge current of the phase winding The initial position of the magnetic pole of the synchronous motor.

Another method is based on the discharge time, which includes the following steps: (a) according to the phase number of the permanent magnet synchronous motor, repeatedly applying a voltage vector pulse wave having a pulse width modulation between the opposite phase windings of the permanent magnet synchronous motor to the permanent magnet synchronous motor until the phase current reaches When the same one of the discharge currents is set, the applied voltage vector is cut off; (b) after the applied voltage vector is cut off, the discharge time when the windings reach the same discharge current is measured; (c) The discharge time at which the same discharge current is reached is measured, and the initial position of the magnetic pole of the permanent magnet synchronous motor is determined.

The above two embodiments for detecting the initial position of the magnetic pole of the permanent magnet synchronous motor are described by using a three-phase permanent magnet synchronous motor, but the same technical method can also be applied to multiphase permanent with more phases than three phases. Magnetic synchronous motor. According to the phase number of the multi-phase permanent magnet synchronous motor, the pulse wave applying the voltage vector with the pulse width modulation is applied to the permanent magnet synchronous motor winding until the current reaches a set discharge current, and then the applied voltage vector is cut off; Measure the discharge current of the winding after a set discharge time after the applied voltage vector is cut off, or measure the discharge time to the same discharge current after the applied voltage vector is cut off, and detect the magnetic pole of the permanent magnet synchronous motor. An initial position; the applied voltage vector pulse is listed in the pulse waveguide duty cycle of the multi-phase permanent magnet synchronous motor, respectively, one phase winding of the permanent magnet synchronous motor winding is connected to the positive end of the DC power supply, and the other phase winding Connected to the negative terminal of the DC power supply, the other phase windings are floated; the phase winding connected to the negative terminal of the DC power supply is connected to the positive terminal of the DC power supply when the next applied voltage vector pulse is listed in the pulse-wave-pass duty cycle. And by the phase winding in the floating phase that has not been connected to the negative end of the DC power supply, alternatively connected to the negative terminal of the DC power supply, at this time, the other phase windings are floated; The number of repeating applying a pulse width modulation voltage to the The pulse wave is listed in the permanent magnet synchronous motor winding and measures the winding discharge current magnitude or discharge time to detect the initial position of the magnetic pole of the permanent magnet synchronous motor; the applied voltage vector pulse wave duty cycle with pulse width modulation, The winding current is rapidly increased, but not enough to cause the permanent magnet synchronous motor to rotate.

Please refer to the control flow 100 for detecting the initial position of the magnetic pole shown in FIG. 6 , which can achieve automatic control and detection through a program or a software, and includes the following steps: Step 110: First, set a reference value N=0, which represents the number of phases of the permanent magnet synchronous motor and the input current set value. The phase number and current setting value of the permanent magnet synchronous motor are set according to the permanent magnet synchronous motor to be detected.

Step 120: Determine whether the reference value N is equal to the number of motor phases. If the detected motor phase number is three-phase, it is judged whether the N value is equal to 3. If N is not equal to 3, then step 130 is performed. If N is equal to 3, then step 160 is performed. Since N sets the initial value to be zero, N is not equal to 3, and step 130 must be performed.

Step 130: Perform two-phase excitation and current decrement. That is, the two-phase excitation mode shown in the above first to third figures, and one of the two embodiments shown in the fourth and fifth figures are performed.

For an embodiment of a control flow for two-phase excitation and current decrement, please refer to the process 200 shown in the seventh figure, which further includes the following steps:

Step 210: Determine whether the phase current reaches a set value. If the phase current does not reach the set value, then step 220 is performed. If the phase current reaches the set value, step 240 is performed.

Step 220: If it is determined in step 210 that the phase current does not reach the set value, the power transmitting phase is turned on by the electronic switch adopting the pulse width modulation mode, and the power receiving phase is turned on. Through the electronic switch, the whole cycle is turned on.

Step 230: Change the pulse width modulation duty cycle, and then repeat step 210 until step 210 determines that the phase current reaches the set value.

Step 240: If it is determined in step 210 that the phase current reaches the set value, the electronic switches of the power transmitting phase and the power receiving phase are turned off.

Step 250: After both the power transmitting phase and the power receiving phase are turned off, the discharging current or the discharging time is recorded, and then returns to the control flow 100 for detecting the initial position of the magnetic pole, and step 140 is performed.

Step 140: When the two-phase excitation and current decrementing process 200 is completed, and the discharge current or discharge time is recorded, the reference value N is incremented by one. For example, the initial reference value is zero, and the reference value is incremented by one after each recording of the discharge current or the discharge time.

Step 150: After the reference value N is accumulated, the excitation phase is changed, and then step 120 is repeated until step 120 determines that the reference value N is equal to the motor phase number.

Step 160: According to the discharge current or the discharge time recorded in step 130 (ie, the process 200), the initial position of the magnetic pole of the initial position of the magnetic pole of the permanent magnet synchronous motor can be obtained by querying a definition table. The content of the reference table varies according to the form of the detected permanent magnet synchronous motor. For the form, refer to Table 1 above.

The method for detecting the initial position of the magnetic pole of the permanent magnet synchronous motor provided by the present disclosure can determine the initial position of the magnetic pole according to the discharge current or the discharge time. The method of the present disclosure only needs to apply a voltage vector with the number of phases, and the present disclosure has a width due to the application. The pulse train of the voltage vector of the modulation can prevent the motor from being pulsed by the voltage vector of the 100% duty cycle. Possible rotation during the initial position detection of the magnetic pole. In addition, the method of exposing the two-phase excitation can obtain accurate results, avoiding the three-phase (above) excitation being caused by the dominant discharge current of the unsaturated phase coil, and the disclosure does not require Additional voltage measurement loop.

However, the above description is only for the embodiments of the present disclosure, and the scope of the disclosure is not limited thereto. That is to say, the average changes and modifications made by the applicants in accordance with the scope of the application for patents should still fall within the scope of the disclosure of this patent. I would like to ask your review committee to give a clear understanding and pray for the best.

100‧‧‧Control flow for detecting the initial position of the magnetic pole

110~160‧‧‧Steps

200‧‧‧Two-phase excitation and current decrement step control process

210~250‧‧‧Steps

i _D , i1‧‧‧ discharge current

t _D , t1‧‧‧ discharge time

U-U‧‧‧ phase winding

V-V‧‧‧ phase winding

W-W‧‧‧ phase winding

+V _DC ‧‧‧DC power supply positive terminal

The first to third figures are schematic views of the winding excitation method disclosed herein.

The fourth figure is a schematic diagram of one embodiment of the duty cycle and magnetic pole initial position detection of the applied voltage vector pulse train.

The fifth figure is another embodiment of the duty cycle of the applied voltage vector pulse train and the initial position detection of the magnetic pole.

The sixth figure is an embodiment of a control flow for detecting the initial position of a magnetic pole.

The seventh figure is an embodiment of the control flow of the two-phase excitation and current decrementing steps in the sixth figure.

i _D ‧‧‧discharge current

T1‧‧‧discharge time

Claims (10)

A method for detecting a magnetic pole initial position of a permanent magnet synchronous motor, comprising the following steps: (a) repeatedly applying a pulse width modulation between the opposite phase windings of the permanent magnet synchronous motor according to the phase number of the permanent magnet synchronous motor The variable voltage vector pulse is listed in the permanent magnet synchronous motor until the phase current reaches the same one of the set discharge currents, and then the applied voltage vector is cut off; (b) after the applied voltage vector is cut off One of the set discharge times, measuring the magnitude of the discharge current of the windings; and (c) determining the initial position of the magnetic poles of the permanent magnet synchronous motor according to the measured magnitudes of the discharge currents of the equal phase windings. The method for detecting a magnetic pole initial position of a permanent magnet synchronous motor according to claim 1, wherein the step (a) further comprises: a pulse waveguide duty cycle of the first applied voltage vector pulse train. Inside, one of the permanent magnet synchronous motors is connected to the positive end of the DC power supply, the other phase winding is connected to the negative end of the DC power supply, and the other phase windings are floated; During the duty cycle of the waveguide of the wave train, the phase winding originally connected to the negative end of the DC power supply is connected to the positive end of the DC power supply, and one of the originally phased windings is connected to the negative end of the DC power supply. The other phase windings are floated; and according to the number of phases of the permanent magnet synchronous motor, the pulse waves repeatedly applying the voltage vector having the pulse width modulation are listed in the windings of the permanent magnet synchronous motor. The method for detecting a magnetic pole initial position of a permanent magnet synchronous motor according to claim 2, wherein the step (a) further comprises: a duty cycle of the applied voltage vector pulse train, enabling the windings The current rises, but the permanent magnet synchronous motor does not rotate. The magnetic pole initial position detecting method of the permanent magnet synchronous motor according to claim 2, wherein the step (b) further comprises: the method for measuring the magnitude of the discharge current of the windings, wherein the measuring is connected to the DC power source. The set of discharge times after the end of each pulse train ends, the magnitude of the current drop, and the magnitude of each current drop. A method for detecting a magnetic pole initial position of a permanent magnet synchronous motor, comprising the following steps: (a) repeatedly applying a pulse width modulation between the opposite phase windings of the permanent magnet synchronous motor according to the phase number of the permanent magnet synchronous motor The variable voltage vector pulse is listed in the permanent magnet synchronous motor until the phase current reaches the same one of the set discharge currents, and then the applied voltage vector is cut off; (b) after the applied voltage vector is separated, Measuring a discharge time when the windings reach the same discharge current; and (c) determining a magnetic pole initial position of the permanent magnet synchronous motor according to the measured discharge time when the same discharge current is reached. The magnetic pole initial position detecting method of the permanent magnet synchronous motor according to claim 5, wherein the step (a) further comprises: a pulse waveguide duty cycle of the first applied voltage vector pulse train. Inside, the permanent magnet synchronous motor has one of the phase windings connected to the The positive end of the current source, the other phase winding is connected to the negative end of the DC power supply, and the other phase windings are floated; in the duty cycle of the pulse wave of the second applied voltage vector pulse train, the original is connected to the DC The phase winding of the negative end of the power supply is connected to the positive end of the DC power supply, and one of the originally floating phase windings is connected to the negative end of the DC power supply, and the other phase windings are floated; and according to the phase of the permanent magnet synchronous motor The pulses repeatedly applied with the voltage vector of the pulse width modulation are listed in the windings of the permanent magnet synchronous motor. The method for detecting a magnetic pole initial position of a permanent magnet synchronous motor according to claim 6, wherein the step (a) further comprises: a duty cycle of the applied voltage vector pulse train, enabling the winding The current rises, but the permanent magnet synchronous motor does not rotate. The method for detecting a magnetic pole initial position of a permanent magnet synchronous motor according to claim 6, wherein the method for measuring a discharge time when the windings reach the same discharge current is determined to be connected to the positive end of the DC power supply. After the end of each pulse train, the current drops to a fixed reference level and the discharge time is compared. A control flow for detecting an initial position of a magnetic pole includes the steps of: first setting a reference value to zero; determining whether the reference value is equal to a phase number of one of the detected permanent magnet synchronous motors; if the reference value is not equal to the Phase number, then two-phase excitation and current decrement, and record a discharge current or a discharge time; Add one, and change the excitation phase, and then repeatedly determine whether the reference value is equal to the phase number until the reference value is equal to the phase number; and according to the recorded discharge current or discharge time, obtain the permanent magnet synchronous motor through the look-up table The initial position of the magnetic pole. The control flow for detecting the initial position of the magnetic pole according to claim 9 of the patent application, wherein the control flow of the two-phase excitation and current decrement further comprises the following steps: determining whether the phase current reaches a set value; if the phase current is not When the set value is reached, the power transmission phase is turned on by the switch pulse width modulation mode, and the power receiving phase is turned on by the switch for full cycle; then the pulse width modulation duty cycle is changed, and then it is repeatedly determined whether the phase current reaches the set value until The phase current reaches the set value; and if it is determined that the phase current reaches the set value, the power transmitting phase and the power receiving phase are turned off, and the discharging current or the discharging time is recorded.