CN108768222A - Inhibit the circuit and control method of brushless DC motor without position sensor commutation torque ripple - Google Patents

Abstract

The invention provides a circuit and a control method for suppressing commutation torque ripple of a position sensorless brushless direct current motor. The DC power supply is connected to the voltage switching circuit based on the single-ended primary inductance converter to provide stable voltage; the voltage switching circuit based on the single-ended primary inductive converter is connected to the three-phase full-controlled bridge inverter circuit to realize the inverter circuit The adjustment of the input voltage; the three-phase full-control inverter circuit is connected with the brushless DC motor, and the three-phase full-control bridge inverter circuit drives the brushless DC motor to work. The present invention reduces the commutation torque problem of the brushless DC motor by rationally adjusting the input voltage of the DC bus voltage, judges the opening and closing of the IGBT tube K through calculation according to the terminal voltage signal detected in real time, and changes the single-ended primary inductance conversion based on The output voltage of the voltage switching circuit of the device does not rely on the Hall sensor, which eliminates the problem of external environment interference that the magnetic sensitive element is susceptible to.

Description

The Circuit and Control of Suppressing Commutation Torque Ripple of Sensorless Brushless DC Motor method

technical field

The invention relates to the technical field of brushless direct current motor control, in particular to a novel circuit topology and control method for suppressing commutation torque ripple of a position sensorless brushless direct current motor.

Background technique

The brushless motor was born in the late 1960s. It is a new type of motor that emerged with the rapid development of permanent magnet material technology, microelectronics and power electronics technology, and control technology.

Brushless DC motor not only has the good speed regulation performance of DC motor, stable operation, and simple control method, but also has the advantages of brushless AC servo system, small size, and stable operation in harsh environments. Therefore, it has a wide range of applications in aerospace, electric vehicles, home appliances and other fields. The DC brushless motor control system must detect the position of the rotor and perform accurate commutation. In this process, the position sensor is necessary. The common DC brushless motor relies on the Hall-type position sensor to detect the rotor position, but Such magnetic sensitive components are easily disturbed by the external environment, which limits the application range of the brushless DC motor control system. In this background, the theory of position sensorless control system is proposed. Moreover, due to its unique motor structure and discontinuous commutation control strategy, the brushless DC motor has the problem of large torque ripple. Torque pulsation causes problems such as noise and vibration in the drive system, affects system reliability, shortens service life, and restricts its application in high-precision and high-stability applications. Among the various torque ripples of brushless DC motors, the commutation torque ripple has a greater influence. In order to effectively suppress the commutation torque ripple, domestic and foreign scholars have done a lot of research.

Contents of the invention

In view of the above prior art, the technical problem to be solved by the present invention is to provide a circuit and a control method for suppressing commutation torque ripple of a position sensorless brushless DC motor by rationally adjusting the input voltage of the DC bus voltage.

In order to solve the above technical problems, the present invention provides a circuit for suppressing commutation torque ripple of a sensorless brushless DC motor, including a DC power supply, a voltage switching circuit based on a single-ended primary inductance converter, and a three-phase fully-controlled bridge inverter circuit ;

The DC power supply is connected to a voltage switching circuit based on a single-ended primary inductance converter to provide a stable voltage;

The voltage switching circuit based on the single-ended primary inductance converter is connected with the three-phase fully-controlled bridge inverter circuit to realize the adjustment of the input voltage of the inverter circuit;

The three-phase full-control inverter circuit is connected with the brushless DC motor, and the three-phase full-control bridge inverter circuit drives the brushless DC motor to work.

As a further improvement of the present invention, the voltage switching circuit based on the single-ended primary inductance converter includes inductor L ₁ , inductor L ₂ , capacitor C ₁ , capacitor C ₂ , diode D ₁ , diode D ₂ , MOSFET tube Q and IGBT tube K ; The positive pole of the DC power supply is connected to _one end of the inductor L1 and the anode of the diode D2 _; the other end of the inductor L1 is connected to _one end of the capacitor _C1 and the source of the MOSFET Q at the same time; the other end of the capacitor _C1 is connected to the inductor _One end of L2 is connected to the anode of diode D1 _; the cathode of diode D1 is connected to _one end of capacitor _C2 and the collector of IGBT tube K; the emitter of IGBT tube K is connected to the cathode end of diode D2 _; DC _The negative pole of the power supply U _i is connected to the drain of the MOSFET Q, the other end of the inductor L2, and the other end of the capacitor _C2 at the same time.

The present invention is a control method of a circuit for suppressing commutation torque ripple of a brushless DC motor without a position sensor, comprising the following steps:

(1) The FPGA data processing unit judges the commutation time of the motor according to the terminal voltage signal of the brushless DC motor, and generates a commutation signal;

(2) Control the IGBT tube K to turn off when the brushless DC motor is not commutating, then the DC power supply is the DC bus voltage of the motor;

(3) Control the conduction of the IGBT tube K at the commutation moment of the brushless DC motor, then the output voltage U _o of the voltage switching circuit based on the single-ended primary inductance converter is the DC bus voltage of the motor;

The FPGA data processing unit calculates the motor speed Ω according to the obtained terminal voltage of the brushless DC motor, and adjusts the duty ratio D of the MOSFET tube Q, so that The relationship between the output voltage U _o of the voltage switching circuit based on the single-ended primary inductance converter and the back electromotive force E _m of the brushless DC motor satisfies U _o = 4E _m , where K _e is the back electromotive force coefficient, U _i is the voltage of the DC power supply, Ω is the brushless DC motor speed.

Beneficial effects of the present invention: the present invention adopts a position sensorless control method based on terminal voltage, and reduces the commutation torque problem of the DC brushless motor by rationally adjusting the input voltage of the DC bus voltage.

(1) This method can judge the turn-on and turn-off of the IGBT tube K through calculation according to the terminal voltage signal detected in real time, and change the output voltage of the voltage switching circuit based on the single-ended primary inductance converter, so that the DC during commutation The relationship between the bus voltage U _dc and the counter electromotive force E _m is maintained as U _dc = 4E _m , without relying on the Hall sensor, eliminating the problem of the external environment that the magnetic sensitive element is susceptible to.

(2) From the perspective of the new circuit topology, during the commutation period, the output voltage of the voltage switching circuit based on the single-ended primary inductance converter will be higher than the power supply voltage, and the current may flow to the power supply, so adding a diode can prevent commutation During the phase period, the current flows to the power supply, thereby reducing the number of switching tubes used. On the other hand, the antiparallel diode inside the switch K provides a channel for the energy fed back by the motor to the _C2 capacitor, which improves the utilization rate of system energy.

Description of drawings

Fig. 1 is a novel circuit topology for suppressing commutation torque ripple of a position sensorless brushless DC motor according to the present invention.

Fig. 2 is a circuit diagram of a three-phase fully-controlled bridge inverter circuit DC brushless motor used in the present invention.

Fig. 3 is a block diagram of a control method for suppressing commutation torque ripple of a brushless DC motor without a position sensor according to the present invention.

Fig. 4 is a waveform diagram of the DC bus voltage before the application of the present invention.

Fig. 5 is a waveform diagram of the DC bus voltage after the use of the present invention.

Fig. 6 is a waveform diagram of the on-phase current i _A and the off-phase current i _B after the use of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

A new circuit topology for suppressing commutation torque ripple of sensorless brushless DC motors, as shown in Figure 1, which includes a DC power supply U _i and a single-ended primary inductor converter (SEPIC) based New voltage switching circuit, three-phase fully-controlled bridge inverter circuit, DC brushless motor. The DC power supply is connected to the new voltage switching circuit based on the SEPIC converter to provide stable voltage; the new voltage switching circuit based on the SEPIC converter is connected to the three-phase full-controlled bridge inverter circuit to realize the adjustment of the input voltage of the inverter circuit ; The three-phase full-control bridge inverter circuit is connected with the DC brushless motor, and the three-phase full-control bridge inverter circuit drives the DC brushless motor to work. Including the following steps:

(1) During the non-commutation period of the brushless DC motor, the tube K is turned off, and the DC input power is the DC bus voltage of the motor.

(2) During the commutation period of the brushless DC motor, the tube K is turned on, and the output voltage of the new voltage switching circuit based on the SEPIC converter is used as the DC bus voltage of the motor. The duty cycle D of the MOSFET tube Q determines the output voltage of the new voltage switching circuit based on the SEPIC converter. The relationship between the output voltage U _o and the duty D of the new voltage switching circuit based on the SEPIC is as follows:

Since the counter electromotive force is proportional to the speed, that is:

E _m = K _e Ω (2)

In order to satisfy the relationship between the output voltage U _o and the counter electromotive force E _m as U _o = 4E _m , so as to effectively suppress the commutation torque ripple, it can be obtained that the MOSFET tube D during the commutation period should satisfy:

It can be seen that the duty cycle of MOSFET Q in the SEPIC converter can be changed by measuring the rotational speed in real time, so as to obtain the desired DC bus voltage satisfying U _dc =4E _m and achieve constant torque. Diode D2 and capacitor _{C2 stabilize} the output voltage.

(3) During the commutation period, the DC bus voltage will be higher than the power supply voltage if U _dc = 4E _m , and the current may flow to the power supply, so adding diode _D2 can prevent the current from flowing to the power supply during the commutation period.

The three-phase winding of the DC brushless motor adopts a star-shaped connection structure, and the three-phase fully-controlled bridge inverter circuit adopts a two-two conduction method. Each power tube conducts 120° and commutates once every 60° electrical angle. The DC brushless motor used is a trapezoidal wave with a back electromotive force of 120° flat top. According to the DC brushless motor circuit diagram of the three-phase fully-controlled bridge inverter circuit shown in Figure 2, it can be obtained:

Among them, u _A , u _B , u _c are the terminal voltages of the three-phase stator windings, i _A , i _B , i _C are the phase currents of the three-phase stator windings, e _A , e _B , e _C are the three-phase electromotive force, R, L, M are the phase resistance, equivalent inductance and equivalent mutual inductance, u _N is the neutral point potential, it can be obtained:

Take the conduction of phase A and B as an example, the relationship between current:

i _A =-i _B , i _C =0 (6)

Back-EMF relationship:

e _A = -e _B (7)

Combine (4), (5), (6), (7) to get:

Then the same can be obtained:

Therefore, the counter EMF zero-crossing signal can be obtained by detecting the terminal voltage signal of the brushless DC motor after calculation, and the commutation information can be provided for the normal operation of the motor after a phase shift of π/6.

According to the schematic diagram of the new circuit topology control method for suppressing brushless DC motor commutation torque ripple shown in Figure 3, the FPGA chip with fast computing speed and strong data processing capability is used as the core data processing unit, including the following steps:

(1) In order to ensure the normal operation of the brushless DC motor, the terminal voltage signal of the brushless DC motor is detected, and then the terminal voltage signal is sent to the FPGA processing chip to generate a commutation signal, which is used to control the correct commutation of the motor.

(2) According to the calculated commutation information, the FPGA processing chip sends a K signal to the switch tube during the non-commutation period of the brushless DC motor to turn off the switch tube. At this time, the DC input power is the DC bus voltage of the motor.

(3) In order to quickly obtain the desired voltage at the time of commutation, the MOSFET Q is switched on and off at a certain duty ratio D, and the duty ratio D of Q is adjusted. The FPGA processing chip can calculate the real-time rotational speed Ω of the motor according to the commutation time information, and can calculate the duty cycle D required to adjust the MOSFET tube Q according to the motor rotational speed, thereby changing the output voltage of the new voltage switching circuit based on the SEPIC converter U _o , so that the relationship between the output voltage U _o and the counter electromotive force E _m is U _o =4E _m .

(4) According to the commutation information obtained, the FPGA processing chip sends the K signal to the switch tube during the commutation period of the brushless DC motor to turn on the switch. At this time, the DC input power is adjusted by a new voltage switching circuit based on SEPIC to meet the voltage U _dc = 4E _m , thereby effectively suppressing commutation torque ripple.

As shown in Figure 4 and Figure 5, they are the DC bus voltage waveforms of the position sensorless brushless DC motor control system before and after adopting this method. It can be seen that the DC bus voltage is constant during commutation before adopting this method. After adopting this method, the DC bus voltage is regulated during the commutation period. Figure 6 is a waveform diagram of the turn-on phase current and turn-off phase current after adopting the present invention, it can be seen that the rate of rise of the turn-on phase current is the same as the rate of drop of the turn-off phase current, thereby reducing the torque ripple generated during commutation .

In summary, a method for suppressing commutation torque ripple of sensorless brushless DC motors can effectively suppress the commutation torque ripple of sensorless brushless DC motors under the premise of reducing the number of switch tubes and simplifying the difficulty of the control system. Phase torque ripple, fast system response, simple method, easy to implement.

Specific embodiments of the present invention also include:

A circuit topology for suppressing commutation torque ripple of a position sensorless brushless DC motor, including a DC power supply U _i , a new voltage switching circuit based on a SEPIC converter, a three-phase fully-controlled bridge inverter circuit, and a DC brushless motor;

The DC power supply is connected with a new voltage switching circuit based on a SEPIC converter to provide a stable voltage;

The new voltage switching circuit based on the SEPIC converter is connected with the three-phase full-control bridge inverter circuit to realize the adjustment of the input voltage of the inverter circuit;

The three-phase full-control bridge inverter circuit is connected with the DC brushless motor, and the three-phase full-control bridge inverter circuit drives the DC brushless motor to work.

The new voltage switching circuit based on SEPIC converter includes inductor L ₁ , inductor L ₂ , capacitor C ₁ , capacitor C ₂ , diode D ₁ , diode D ₂ , MOSFET tube Q and IGBT tube K;

The positive pole of the DC power supply _Ui is connected to _one end of the inductor L1 and the anode of the diode D2 _;

The other end of the inductor L1 is simultaneously connected to _one end of the capacitor _C1 and the source of the MOSFET Q;

_The other end of the capacitor _C1 is simultaneously connected with _one end of the inductor L2 and the anode of the diode D1;

The cathode of the diode D1 is connected to _one end of the capacitor _C2 and the collector of the IGBT tube K;

The emitter of the IGBT tube K is connected to the cathode end of the diode D2 _;

_The negative pole of the DC power supply _Ui is connected to the drain of the MOSFET Q, the other end of the inductor L2, and the other end of the capacitor _C2 at the same time.

A control method for a circuit for suppressing commutation torque ripple of a sensorless brushless DC motor, specifically comprising the following steps:

(1) The FPGA-based data processing unit judges the commutation time of the motor based on the obtained terminal voltage signal. When the brushless DC motor is not commutating, the control tube K is turned off, and the DC input power is the DC bus voltage of the motor.

(2) In order to quickly obtain the desired DC bus voltage at the time of commutation, the MOSFET Q is switched on and off with a certain duty ratio D, and the data processing unit with FPGA as the core calculates the motor speed according to the obtained terminal voltage information. Further calculate the value of the duty cycle D, adjust the duty cycle of Q to change the output voltage U _o of the new voltage switching circuit based on the SEPIC converter, so that the relationship between the output voltage U _o and the counter electromotive force E _m is U _o = 4E _m .

(3) When the brushless DC motor is commutating, the control tube K is turned on, and the output voltage of the new circuit based on the SEPIC converter is used as the DC bus voltage U _dc = 4E _m of the motor, thereby reducing the commutation of the sensorless brushless DC motor Phase torque ripple.

The invention provides a circuit and a control method for suppressing commutation torque ripple of a position sensorless brushless direct current motor. Since the three-phase winding of a brushless DC motor can be regarded as an inductive load, the current rises or falls at a certain rate during commutation. Fluctuation, resulting in motor commutation torque pulsation. In the present invention, a novel voltage switching circuit based on a SEPIC converter is adopted to input the terminal voltage of the brushless DC motor to the data processing unit with the FPGA as the core; the data processing unit with the FPGA as the core judges the motor according to the received terminal voltage signal At the commutation moment, adjust the output voltage of the new voltage switching circuit based on the SEPIC converter so that the DC bus voltage is the expected value. This method suppresses the torque ripple problem caused during the commutation period by adjusting the DC bus voltage during the commutation period.

Claims (3)

1. a kind of circuit inhibiting brushless DC motor without position sensor commutation torque ripple, it is characterised in that：Including direct current Power supply, the voltage commutation circuit based on single ended primary induction converter, three-phase fully-controlled bridge inverter circuit；

DC power supply is connect with the voltage commutation circuit based on single ended primary induction converter, to provide stable voltage；

Voltage commutation circuit based on single ended primary induction converter is connect with three-phase fully-controlled bridge inverter circuit, is realized to inversion electricity The adjustment of road input voltage；

Three-phase fully-controlled inverter circuit is connected with brshless DC motor, and three-phase fully-controlled bridge inverter circuit drives brshless DC motor work Make.

2. a kind of circuit inhibiting brushless DC motor without position sensor commutation torque ripple according to claim 1, It is characterized in that：The voltage commutation circuit based on single ended primary induction converter includes inductance L₁, inductance L₂, capacitance C₁、 Capacitance C₂, diode D₁, diode D₂, MOSFET pipe Q and IGBT pipes K；

Anode and the inductance L of DC power supply₁One end and diode D₂Anode connection；

Inductance L₁The other end simultaneously with capacitance C₁One end connected with the source electrode of MOSFET pipes Q；

Capacitance C₁Other end L with inductance simultaneously₂One end and diode D₁Anode connection；

Diode D₁Cathode and capacitance C₂One end connected with the collector of IGBT pipes K；

The emitter of IGBT pipes K and diode D₂Cathode one end be connected；

DC power supply U_iCathode drain electrode with MOSFET pipes Q simultaneously, inductance L₂The other end, capacitance C₂The other end be connected.

3. a kind of circuit of inhibition brushless DC motor without position sensor commutation torque ripple as claimed in claim 1 or 2 Control method, which is characterized in that include the following steps：

(1) FPGA data processing unit judges that the commutation moment of motor, generation change according to the terminal voltage signal of brshless DC motor Phase signals；

(2) the K shutdowns of IGBT pipes are controlled in the non-commutation of brshless DC motor, then DC power supply is the DC bus-bar voltage of motor；

(3) in the conducting of brshless DC motor commutation moment control IGBT pipes K, then the voltage based on single ended primary induction converter is cut Change the output voltage U of circuit_oFor the DC bus-bar voltage of motor；

Motor speed Ω is calculated according to the terminal voltage of the brshless DC motor of acquisition in FPGA data processing unit, adjustment The duty ratio D of MOSFET pipes Q is enabledThe output electricity of voltage commutation circuit based on single ended primary induction converter Press U_oWith brushless direct-current machine counter electromotive E_mBetween meet U_o=4E_m, wherein K_eFor back EMF coefficient, U_iFor DC power supply Voltage, Ω are brshless DC motor rotating speed.