CN106788071A - A kind of method for improving permanent-magnet synchronous motor rotor position estimated accuracy - Google Patents

Abstract

The invention discloses a method for improving the position estimation accuracy of a permanent magnet synchronous motor. The method processes the extracted position estimation error function on the basis of realizing the rotor position estimation of the permanent magnet synchronous motor by using the pulse vibration high-frequency voltage injection method , eliminate the 2nd harmonic component introduced due to the asymmetry of the motor parameters, obtain the processed position estimation error function, and then establish a phase-locked loop to adjust it to 0, and obtain the estimated rotor speed and estimated rotor position. This method can effectively suppress the second harmonic error of position estimation caused by the asymmetry of motor parameters, and improve the performance of the position sensorless control system.

Description

A Method of Improving the Estimation Accuracy of Rotor Position of Permanent Magnet Synchronous Motor

technical field

The invention relates to the field of motor control, in particular to a method for improving the estimation accuracy of the rotor position of a permanent magnet synchronous motor.

Background technique

Permanent magnet synchronous motors have been widely used in industry due to their small size, light weight, high power factor and superior control performance. Rotor position is the indispensable information for permanent magnet synchronous motor to realize vector control. Mechanical position sensors such as photoelectric encoder and resolver increase the volume, weight and cost of the control system. Therefore, the position sensorless control technology of permanent magnet synchronous motor is obtained. received widespread attention. Among them, the pulse vibration high-frequency voltage injection method is simple to implement, has good robustness, and is suitable for zero and low speed applications, so it attracts a large number of scholars to study it.

The rotor position estimation accuracy is an important index to consider the performance of a positionless control system. When the three-phase resistance or inductance of the motor is asymmetrical, there is a second harmonic error in the estimated rotor position obtained by the pulse vibration high-frequency voltage injection method. The existence of this harmonic error reduces the accuracy of rotor position estimation, and also limits the improvement of position sensorless control performance, so it is necessary to eliminate it. P.L.Xu and Z.Q.Zhu, "Carrier signal injection-based sensorless control for permanent-magnet synchronous machine drives considering machine parameter asymmetry," IEEE Trans.Ind.Electron., vol.63, no.5, pp.2813-2824, May.2016 .A method for suppressing the 2nd harmonic of rotor position estimation error based on dual signal injection is proposed. Two signals of different frequencies are injected on the direct axis, and the amplitude and frequency ratio of the two injected signals are guaranteed to be consistent. Modulate one of the signals to obtain the deviation related to the asymmetry of the motor parameters, and use it to compensate the position estimation error information in the modulation process of the other signal. This method effectively suppresses the 2nd harmonic component in the estimated position, but Since two signals of different frequencies need to be injected, this obviously increases the computational burden and complexity of the system.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for improving the estimation accuracy of the rotor position of a permanent magnet synchronous motor, which can effectively suppress the second harmonic error in the estimation of the rotor position and improve the estimation accuracy of the rotor position.

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

A method for improving the rotor position estimation accuracy of a permanent magnet synchronous motor proposed according to the present invention comprises the following steps:

Step A, using the pulse vibration high-frequency voltage injection method to obtain position estimation error information;

Step B. Modulating the extracted position estimation error information to first obtain compensation information, and then making a difference between the position estimation error information and the compensation information to obtain processed position estimation error information;

Step C, establishing a phase-locked loop, adjusting the processed position estimation error information to 0, and obtaining an estimated rotor speed and an estimated rotor position;

Step D. Obtain the estimated d-axis and q-axis voltages according to the current given value and current response of the estimated d-axis and q-axis;

Step E, repeat steps A to D until the motor stops running.

As a further optimization scheme of the method for improving the estimation accuracy of the rotor position of the permanent magnet synchronous motor described in the present invention, the step A is specifically as follows:

Step A.1. Inject a high-frequency cosine voltage U _h cos(ω _h t) on the d-axis of the estimated rotor synchronous rotation coordinate system, where U _h is the amplitude of the high-frequency voltage injected on the d-axis, and ω _h is the amplitude at d The frequency at which the axis injects high-frequency voltage, t represents the current moment;

Step A.2. Estimating the d-axis voltage and estimated q-axis voltage Carry out parker inverse transformation to obtain the voltages u _α and u _β in the two-phase stationary α-β coordinate system, and then use space vector pulse width modulation to obtain six-way switching signals of the three-phase inverter to drive the permanent magnet synchronous motor;

Step A.3. Detect any two-phase current in the three-phase winding A/B/C of the motor, first perform Clarke transformation to obtain the currents i _α and i _β in the two-phase static α-β coordinate system, and then obtain estimates through Parker transformation d-axis current response and estimate the q-axis current response

Step A.4, will estimate the q-axis current response The AC component with a frequency of ω _h is selected through a band-pass filter, that is, the high-frequency component Then multiplied with the sinusoidal signal 2sin(ω _h t) for modulation to obtain the DC component and the AC component with a frequency of 2ω _h , and finally pass the DC component and AC component through a low-pass filter to filter out the AC component, extract the DC component, and obtain Position estimation error information f(Δθ).

As a further optimization scheme of the method for improving the estimation accuracy of the rotor position of the permanent magnet synchronous motor described in the present invention, the step B is specifically as follows:

Step B.1. Combine the position estimation error information f(Δθ) with multiplied, where is the estimated rotor position;

Step B.2, adopt a cut-off frequency lower than pair of low-pass filters f(Δθ) for filtering, where, to estimate the rotor speed;

Step B.3, combine the filtered signal with Multiply to get the compensation information f _P ;

Step B.4. Making a difference between the position estimation error information f(Δθ) and the compensation information f _P to obtain the processed position estimation error information f _c (Δθ).

As a further optimization scheme of the method for improving the rotor position estimation accuracy of the permanent magnet synchronous motor described in the present invention, the estimated rotor speed and the estimated rotor position are obtained in the step C, specifically as follows:

Step C.1. The processed position estimation error information f _c (Δθ) is used as the input of the PI regulator, and the output of the PI regulator is the estimated rotor speed

Step C.2. Estimated rotor speed Integrate to get estimated rotor position

As a further optimization scheme of the method for improving the estimation accuracy of the rotor position of the permanent magnet synchronous motor described in the present invention, the step D is specifically as follows:

Step D.1. Comparing the given rotor speed ω ^* with the estimated rotor speed The difference is input to the speed loop PI regulator, and the output of the PI regulator is the estimated q-axis current given value

Step D.2, will estimate the given value of the d-axis current Set to 0, will estimate d-axis current given value with the low-pass filtered estimated d-axis current response For poor results, estimate the q-axis current given value with the low-pass filtered estimated q-axis current response The result of the difference is passed through the current loop PI regulator to obtain the estimated d-axis voltage and estimated q-axis voltage

Compared with the prior art, the present invention adopts the above technical scheme and has the following technical effects:

(1) The acquisition process of the deviation information caused by the asymmetry of the motor parameters does not require additional injection signals, but only requires a certain modulation of the current response of the injected high-frequency signals;

(2) This compensation method only needs to add one more low-pass filter, which is simple and convenient to implement, and the calculation burden is small;

(3) After adopting this compensation method, the 2nd harmonic content in the position estimation error is significantly reduced, and the position estimation accuracy is significantly improved.

Description of drawings

Fig. 1 is a functional block diagram of a permanent magnet synchronous motor position sensorless control system with a 2nd harmonic error suppression function.

Fig. 2 is a functional block diagram of the 2nd harmonic error elimination module of the estimated position.

Figure 3 shows the actual rotor position θ and estimated rotor position with and without compensation at a given speed of 120r/min Experimental waveforms of the position estimation error Δθ and the processed position estimation error information f _c (Δθ).

detailed description

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

As shown in accompanying drawing 1, the present invention provides a kind of method for improving the position estimation precision of permanent magnet synchronous motor, specifically comprises the following steps:

Step 1) Inject a high-frequency cosine voltage U _h cos(ω _h t) on the d-axis of the estimated rotor synchronous rotation coordinate system, where U _h is the amplitude of the high-frequency voltage injected on the d-axis, and ω _h is the amplitude of the injected high-frequency voltage on the d-axis The frequency of the high-frequency voltage, t represents the current moment;

Step 2) To estimate the d-axis and q-axis voltage with Carry out Parker inverse transformation to obtain the voltages u _α and u _β in the two-phase static α-β coordinate system, and then use space vector pulse width modulation SVPWM to obtain six-way switching signals of the three-phase inverter to drive the permanent magnet synchronous motor PMSM, where , with The initial value of is 0;

Step 3) Detect any two-phase current in the three-phase winding A/B/C of the motor, first perform Clarke transformation to obtain the currents i _α and i _β in the two-phase static α-β coordinate system, and then obtain the estimated d-axis through Parker transformation current response and estimate the q-axis current response

Step 4) will estimate the q-axis current response The AC component with a frequency of ω _h is selected through a band-pass filter (BPF), that is, the high-frequency component Then multiplied with the sinusoidal signal 2sin(ω _h t) for modulation to obtain a DC component and an AC component with a frequency of 2ω _h , and finally filter out the AC component through a low-pass filter (LPF), extract the DC component, and obtain the position estimation error information f(Δθ).

Step 5) As shown in accompanying drawing 2, the position estimation error information f(Δθ) and multiplied, where The initial value of is 0;

Step 6) Use a cutoff frequency well below The low-pass filter LPF2 pairs f(Δθ) for filtering, where, The initial value of is 0;

Step 7) Combine the filtered signal with Multiply to get the compensation information f _P ;

Step 8) Make a difference between the position estimation error information f(Δθ) and the compensation information f _P to obtain the processed position estimation error information f _c (Δθ).

Step 9) Use the processed position estimation error information f _c (Δθ) as the input of the PI regulator to estimate the rotor speed is the output of the PI regulator, the estimated rotor speed for Integrate to get estimated rotor position

Step 10) Compare the given rotor speed ω ^* with the estimated rotor speed The difference is input to the speed loop PI regulator, and the output of the PI regulator is the estimated q-axis current given value

Step 11) will estimate the d-axis current setpoint Set to 0, the d-axis and q-axis current given values will be estimated respectively with Estimated d-axis and q-axis current responses with low-pass filter (LPF) with As a difference, through the current loop PI regulator, the estimated d-axis and q-axis voltages are obtained with

Step 12) Repeat step 1) to step 11) until the motor stops running.

In order to verify the feasibility of the method proposed in the present invention, an experiment was carried out on a PMSM with a rated power of 1.5kW. Accompanying drawing 3 is when given rotating speed is 120r/min, adopts the compensation method proposed by the present invention and when not adopting this compensation method the experimental waveform of actual rotor position, estimated rotor position, position estimation error and position estimation error information after processing . The comparison shows that without compensation, the position estimation error information and the position estimation error contain obvious 2nd harmonic components, and the position estimation accuracy is poor; when there is compensation, the position estimation error information and the 2nd harmonic components in the position estimation error The position estimation accuracy is significantly improved.

Claims (5)

1. A method for improving the rotor position estimation accuracy of permanent magnet synchronous motor, is characterized in that, comprises the following steps: Step A, using the pulse vibration high-frequency voltage injection method to obtain position estimation error information; Step B. Modulating the extracted position estimation error information to first obtain compensation information, and then making a difference between the position estimation error information and the compensation information to obtain processed position estimation error information; Step C, establishing a phase-locked loop, adjusting the processed position estimation error information to 0, and obtaining an estimated rotor speed and an estimated rotor position; Step D. Obtain the estimated d-axis and q-axis voltages according to the current given value and current response of the estimated d-axis and q-axis; Step E, repeat steps A to D until the motor stops running. 2. a kind of method for improving the rotor position estimation precision of permanent magnet synchronous motor according to claim 1, is characterized in that, described step A is specifically as follows: Step A.1. Inject a high-frequency cosine voltage U _h cos(ω _h t) on the d-axis of the estimated rotor synchronous rotation coordinate system, where U _h is the amplitude of the high-frequency voltage injected on the d-axis, and ω _h is the amplitude at d The frequency at which the axis injects high-frequency voltage, t represents the current moment; Step A.2. Estimating the d-axis voltage and estimated q-axis voltage Carry out Parker inverse transformation to obtain the voltages u _α and u _β in the two-phase static α-β coordinate system, and then use space vector pulse width modulation to obtain six-way switching signals of the three-phase inverter to drive the permanent magnet synchronous motor; Step A.3. Detect any two-phase current in the three-phase winding A/B/C of the motor, first perform Clarke transformation to obtain the currents i _α and i _β in the two-phase static α-β coordinate system, and then obtain estimates through Parker transformation d-axis current response and estimate the q-axis current response Step A.4, will estimate the q-axis current response The AC component with a frequency of ω _h is selected through a band-pass filter, that is, the high-frequency component Then multiplied with the sinusoidal signal 2sin(ω _h t) for modulation to obtain a DC component and an AC component with a frequency of 2ω _h , and finally pass the DC component and AC component through a low-pass filter to filter out the AC component, extract the DC component, and obtain Position estimation error information f(Δθ). 3. a kind of method for improving the rotor position estimation precision of permanent magnet synchronous motor according to claim 1, is characterized in that, described step B is specifically as follows: Step B.1. Combine the position estimation error information f(Δθ) with multiplied, where is the estimated rotor position; Step B.2, adopt a cut-off frequency lower than pair of low-pass filters filter, where to estimate the rotor speed; Step B.3, combine the filtered signal with Multiply to get the compensation information f _P ; Step B.4. Making a difference between the position estimation error information f(Δθ) and the compensation information f _P to obtain the processed position estimation error information f _c (Δθ). 4. a kind of method for improving the rotor position estimation precision of permanent magnet synchronous motor according to claim 1, is characterized in that, obtains estimated rotor speed and estimated rotor position in described step C, specifically as follows: Step C.1. The processed position estimation error information f _c (Δθ) is used as the input of the PI regulator, and the output of the PI regulator is the estimated rotor speed Step C.2. Estimated rotor speed Integrate to get estimated rotor position 5. a kind of method for improving the rotor position estimation precision of permanent magnet synchronous motor according to claim 1, is characterized in that, described step D is specifically as follows: Step D.1. Comparing the given rotor speed ω ^* with the estimated rotor speed The difference is input to the speed loop PI regulator, and the output of the PI regulator is the estimated q-axis current given value Step D.2, will estimate the given value of the d-axis current Set to 0, will estimate d-axis current given value with the low-pass filtered estimated d-axis current response As a result of the difference, estimate the q-axis current given value with the low-pass filtered estimated q-axis current response The result of the difference is passed through the current loop PI regulator to obtain the estimated d-axis voltage and estimated q-axis voltage