CN102923189B - A kind of electric booster steering system controller based on permagnetic synchronous motor and control method - Google Patents

Abstract

The present invention discloses a kind of electric booster steering system controller based on permagnetic synchronous motor and control method.Controller part constructs steering wheel torque and angular signal acquisition system, motor rotor position signal acquiring system, PMSM Drive System and CAN communication system.Control method part includes electric power-assisted steering control method, method for controlling permanent magnet synchronous motor, motor rotor position signal calculation method and steering wheel torque angular signal calculation method.Present invention employs novel motor position sensor and steering wheel torque rotary angle transmitter, by the Rational of controller and control method being achieved the excellent control to electric boosting steering system based on permagnetic synchronous motor so that electric boosting steering system is the most perfect.

Description

A permanent magnet synchronous motor based electric power steering system controller and control method

technical field

The invention belongs to the technical field of vehicle steering control, in particular to a controller and a control method of an electric power steering system based on a permanent magnet synchronous motor.

Background technique

The electric power steering system has developed rapidly in recent years, and the performance of the entire system has become more and more reliable and perfect. The development of the electric power steering system includes the following characteristics: First, the motor used in the electric power steering system transitions from a brushed DC motor to a permanent magnet synchronous motor to solve the problem of brushes and commutators in the brushed DC motor. This results in problems such as short system life and difficult maintenance. Second, the electric power steering control method is developing from a simple linear power steering control method to a control method that can better improve the driver's feel and vehicle handling stability. Third, a low-cost, high-precision, and high-reliability motor rotor position sensor is produced. Fourth, the steering wheel torque and angle sensor is developing in the direction of non-contact, high precision and high anti-interference. The application of these new devices and methods can greatly improve the performance and reliability of the electric power steering system, but at the same time, the whole system is more complicated and the design difficulty is increased.

Contents of the invention

Aiming at the development characteristics of the above-mentioned electric power steering system, the present invention integrates these new devices and methods, gives full play to the advantages of each device and method, and provides a permanent magnet synchronous motor-based electric power steering system controller and Control Method.

Technical scheme of the present invention is realized like this:

The present invention adopts the electric power steering system based on the permanent magnet synchronous motor as the control object. Compared with the brushed DC motor, the permanent magnet synchronous motor used in this system has the advantages of simple structure, small size, reliable operation, long life, and high power density. At the same time, the control system is more complicated from software to hardware; the motor in this system The rotor position sensor includes three-way commutation Hall signals and two-way position Hall signals. On the premise of ensuring the accuracy of the rotor position, the cost is significantly reduced. It is very suitable for electric power steering systems and promotes the use of permanent magnet synchronous motors in Application in electric power steering system; the steering wheel torque angle sensor in this system is a non-contact inductive position sensor, which outputs two torque signals based on the SENT protocol and one PWM signal-like angle signal. The sensor has It has the characteristics of high precision, high resolution, high temperature stability, strong anti-interference ability and convenient installation.

Aiming at the electric power steering system, the present invention constructs a permanent magnet synchronous motor-based controller and a control method for the electric power steering system. The control method of the present invention includes four parts: an electric power steering control method, a permanent magnet synchronous motor control method, a motor rotor position signal solving method and a steering wheel torque angle signal solving method.

On the controller, this patent takes the main control chip TMS320F2812 as the core, constructs the steering wheel torque angle signal acquisition circuit, the motor rotor position signal acquisition circuit, the permanent magnet synchronous motor drive circuit and the CAN communication circuit.

In the control method, the electric power steering control method adopts the multi-point broken line basic power assist control method, the motor compensation control method and the centering control method. The multi-point broken line basic power assist control method has a relatively smooth power assist curve, is simple to implement, and is easy to modify and debug. The motor compensation control method includes a friction compensation control method, a damping compensation control method and an inertia compensation control method, which reduce or offset the friction force, damping force and inertial force generated by adding a motor and a reduction mechanism to the steering system. The centering control method can improve the lack of centering at low speed and overshooting at high speed, so that the vehicle can obtain good steering centering performance.

The control method of permanent magnet synchronous motor adopts the vector control method with relatively sophisticated technology, and converts the three-phase current based on the stationary stator into the two-phase current based on the rotating rotor through coordinate transformation, so as to realize the sum of the current and the current in the excitation direction of the permanent magnet. Decoupling of currents perpendicular to the excitation direction. Finally, the switching time of each switching device is generated by the space pulse width vector modulation method and the seven-segment method.

The motor rotor position signal calculation method includes four parts: the determination of the initial rotation angle of the motor rotor position, the determination of the absolute base position of the motor rotor, the calculation of the absolute position of the motor rotor, and the verification of the absolute position of the motor rotor.

The steering wheel torque angle signal calculation method includes four parts: SENT signal acquisition, SENT signal calculation, PWM-like signal acquisition and PWM-like signal calculation.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

FIG. 1 is a schematic diagram of the controller structure of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

FIG. 2 is a schematic diagram of the overall architecture of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

3 is a schematic diagram of an electric power steering control method based on a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

4 is a schematic diagram of a multi-point broken line basic assist curve in an electric power steering control method based on a permanent magnet synchronous motor electric power steering system controller and control method according to the present invention.

Fig. 5 is a schematic diagram of signals of a permanent magnet synchronous motor rotor position sensor of a permanent magnet synchronous motor based electric power steering system controller and control method according to the present invention.

Fig. 6 is a schematic diagram of logic for judging the initial value of the rotor position of the permanent magnet synchronous motor according to the controller and the control method of the electric power steering system based on the permanent magnet synchronous motor according to the present invention.

Fig. 7 is a schematic flow chart of determining the absolute basic position of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

FIG. 8 is a schematic diagram of a torque angle sensor SENT signal of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

FIG. 9 is a schematic diagram of a torque angle sensor-like PWM signal of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

FIG. 10 is a schematic diagram of a SENT signal acquisition process of a permanent magnet synchronous motor-based electric power steering system controller and a control method according to the present invention.

FIG. 11 is a schematic diagram of a SENT signal calculation process of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

Fig. 12 is a schematic diagram of a PWM-like signal acquisition process of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

FIG. 13 is a schematic diagram of a PWM-like signal calculation process of a permanent magnet synchronous motor-based electric power steering system controller and control method according to the present invention.

In Figure 1: 1. Main control chip TMS320F2812; 2. Bus transceiver 74HC245; 3. Driver chip IR2130; 4. Bootstrap circuit; 5. Three-phase full-bridge power circuit; 6. Permanent magnet synchronous motor; 7. Current sensor ; 8. Current signal RC filter circuit; 9. Current signal operational amplifier circuit; 10. Motor rotor position sensor; 11. Motor rotor position signal RC filter circuit; 12. Motor rotor position signal twice reverse circuit; 13. Steering wheel rotation Torque angle sensor; 14. Steering wheel torque angle signal RC filter circuit; 15. Steering wheel torque angle signal twice reverse circuit; 16. CAN bus; 17. CAN communication transceiver.

In Fig. 2: 1. permanent magnet synchronous motor; 2. motor rotor position sensor; 3. steering wheel torque angle sensor.

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

Fig. 1 is a structural schematic diagram of the controller of the present invention. The main control chip adopted in the present invention is a digital signal processor TMS320F2812 produced by Texas Instruments. The present invention uses TMS320F2812 as the core to design a motor rotor position signal acquisition circuit, a steering wheel torque angle signal acquisition circuit, a permanent magnet synchronous motor drive circuit and a CAN communication circuit.

Both the motor rotor position signal and the steering wheel torque angle signal pass through the RC filter circuit and the two reverse circuits composed of Schmitt triggers in order to eliminate high-frequency interference, signal shaping, and convert the signal from 5V to 3.3V role. The motor rotor position signal HALLa is connected to the main control GPIOB0 pin, HALLb is connected to the main control GPIOB1 pin, HALLc is connected to the main control GPIOB2 pin, QEP1 is connected to the main control QEP4 pin, and QEP2 is connected to the main control QEP5 pin. The torque angle signal SENTA is connected to the main control CAP1 pin, SENTB is connected to the main control CAP2 pin, and the PWM-like signal is connected to the main control CAP3 pin.

In the permanent magnet synchronous motor drive circuit, the drive signal first passes through the bus transceiver 74HC245, which converts the drive signal from 3.3V to 5V, improves the load capacity of the drive signal, and isolates the drive circuit from the main control circuit. Then the three high-side switching signals PWM1, PWM3, and PWM5 are respectively connected to HIN1, HIN2, and HIN3 of the driver chip IR2130, and the three low-side switching signals PWM2, PWM4, and PWM6 are respectively connected to HIN4, HIN5, and HIN6 of the driver chip IR2130. After the drive signal passes through the IR2130, the high-side switch signal needs to be further boosted by the bootstrap circuit to control the three full-bridge power circuits to drive the permanent magnet synchronous motor to run. Since the motor windings are connected in a star shape, the sum of the three-phase currents is zero, so only two phase currents need to be collected. Install two current sensors from the phase wires A and B of the motor. The current signal sent by the current sensor passes through the RC filter and the operational amplifier circuit to filter out high-frequency interference and convert the 5V signal into 3V. The current analog signal enters the ADINA1 and ADINA2 pins of the main control chip.

The CAN communication circuit connects CAN_H and CAN_L of the CAN bus to a transceiver, and then accesses the main control chip CANTXA and CANRXA pins.

Fig. 2 is a schematic diagram of the overall architecture of the control method of the present invention. The control method mainly includes four parts: the electric power steering control method, the permanent magnet synchronous motor control method, the motor rotor position signal calculation method, and the steering wheel torque angle signal calculation method. There are also four modules corresponding to the structure: Power steering control module, permanent magnet synchronous motor control module, motor rotor position signal calculation module and steering wheel torque angle signal calculation module. The target current in the q-axis direction of the permanent magnet synchronous motor is obtained through the control method of the electric power steering system through the steering wheel torque angle information obtained by collecting and solving and the vehicle speed information obtained through the CAN bus. Input the target current in the q-axis direction of the permanent magnet synchronous motor, the actual current of the three phase lines of the permanent magnet synchronous motor, and the rotor position information of the permanent magnet synchronous motor obtained by acquisition and calculation into the permanent magnet synchronous motor control method, and output the drive signal , and then through the drive circuit, finally realize the boost torque required to control the output of the motor.

Fig. 3 is a schematic diagram of the electric power steering control method of the present invention. The electric power steering control method includes three parts: the basic power assist control method, the motor compensation control method, and the centering control method, and the structure also corresponds to the basic power assist control module, the motor compensation control module, and the centering control module. Among them, the magnitude of the current generated by the basic power assist control method is related to the steering wheel torque and vehicle speed, and the determination of the power assist curve should take into account the steering portability and handling stability. The motor compensation control method reduces or offsets the frictional force, damping force and inertial force generated by adding the motor and the reduction mechanism to the steering system, and improves the dynamic response effect of the electric power steering system. The centering control method can improve the lack of centering at low speed and overshooting at high speed, so that the vehicle can obtain good steering centering performance. The basic boost control current I _b , the motor compensation control current I _c , and the return control current I _r , the sum of these three parts constitutes the motor q-axis target current I _qref .

Referring to FIG. 4 , the basic boosting control method in the present invention adopts a multi-point broken line basic boosting curve. The advantage of using multi-point polylines is that it can approach the effect of a curved assist curve, and at the same time, it is simple to implement and easy to debug and modify. The method of realizing the multi-point broken line boost curve is to divide the vehicle speed signal V into the first segment: 0Km/h to 10Km/h, the second segment: 10Km/h to 20Km/h until the ninth segment: 80Km/h to 90Km /h, paragraph 10: greater than 90Km/h. Each segment corresponds to a multi-point broken line of steering wheel torque versus basic assist current. Each multi-point polyline should first determine 9 feature points: [T _sn1 , I _bn1 ], [T _sn2 , I _bn2 ], ..., [T _sn8 , I _bn8 ], [T _sn9 , I _bn9 ]. Then the multi-point polyline can be expressed as:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}& {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}\\ <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>\\ <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>\\ <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 9</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 8</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 9</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 8</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 8</span>}}& {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 9</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; bn</span>}\mathrm{<span\; class="notranslate">\; 9</span>}}& {\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; sn</span>}\mathrm{<span\; class="notranslate">\; 9</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.$

Referring to Fig. 3, the motor compensation control method includes friction compensation control, damping compensation control and inertia compensation control. Friction compensation control current I _f , damping compensation control current I _d , inertia compensation control current I _i , the sum of these three parts constitutes the motor compensation control current I _c .

Friction compensation control is to overcome Coulomb friction in the motor and its reduction mechanism, and its form is: K _f is the friction compensation coefficient, θ is the motor revolution.

Damping compensation control is to overcome the viscous resistance in the motor and its reduction mechanism, and its form is: K _d is the friction compensation coefficient.

Inertia compensation control is to overcome the inertial force in the motor and its reduction mechanism, and its form is: K _i is an inertia compensation coefficient.

Referring to FIG. 3 , the return-to-center control method includes two parts: return-to-center judgment and return-to-center current control. The logic of back-to-center judgment is that when the absolute value of the steering wheel torque T _s is less than a fixed value T _sr and the absolute value of the steering wheel angle θ _s is greater than a fixed value θ _sr , it indicates that the steering wheel is in the state of letting go and returning to the center. positive current control. The target steering wheel angle is set to 0°. By PID control of the steering wheel angle θ _s , the return current is obtained, and the maximum and minimum values of the return current are limited at different vehicle speeds V, so as to improve the low-speed return of the steering wheel. Insufficient, high-speed back to normal overshoot phenomenon.

Referring to Fig. 2, the method of vector control is adopted in the control of the permanent magnet synchronous motor in the present invention. The three-phase currents I _A , I _B and I _C of the motor are transformed into the actual current I _d in the d-axis direction of the motor and the actual current I _q in the q-axis direction through Clark transformation and Park transformation. The target current I _dref in the d-axis direction of the motor is set to 0, which is subtracted from the actual current I _d in the d-axis direction of the motor, and then enters the d-axis current PID control module. The target current I _qref in the q-axis direction of the motor obtained by the electric power steering control method is subtracted from the actual current I _q in the q-axis direction of the motor, and then enters the q-axis current PID control module. The two PID control modules respectively output the motor d-axis direction target voltage U _dref and the motor q-axis direction target voltage U _qref , and then obtain the motor α-axis direction target voltage U _αref and the motor β-axis direction target voltage U _βref through Park inverse transformation. Finally, the duty cycle signals of each switching device are output through the space voltage vector pulse width modulation method and the seven-segment method. The motor rotor position signal θ is used in both the Park transformation and the Park inverse transformation.

Clark transformation refers to transforming the static ABC three-phase coordinate system composed of motor three-phase windings A, B, and C into a static αβ two-phase coordinate system. The direction of the α-axis is opposite to the winding direction of the phase A of the motor, and the direction of the β-axis rotates 90° counterclockwise along the direction of the phase A of the winding. The formulas for converting three-phase currents I _A , I _B and I _C into two-phase currents I _α and I _β in the patent are:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}}\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 1</span>}& <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; -</span>\frac{\sqrt{\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}\end{array}\right]$

Park transformation refers to transforming the αβ two-phase coordinate system in which the motor is stationary into the dq two-phase coordinate system that rotates with the rotor. The direction of the d-axis is the excitation direction of the permanent magnet, the direction of the q-axis is the excitation direction of the permanent magnet rotated 90° counterclockwise, and the angle between the direction of the d-axis and the direction of the phase A of the motor is θ. The formula for converting static two-phase currents I _α and I _β into rotating two-phase currents I _d and I _q in the patent is:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}& \mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}\\ <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}& \mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}\end{array}\right]$

Park inverse transformation refers to transforming the dq two-phase coordinate system that rotates with the rotor into the αβ two-phase coordinate system that the motor is stationary. The formula for converting the rotating two-phase target voltage U _dref and U _qref into the stationary two-phase target voltage U _αref and U _βref in the patent is:

$\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;ref</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;ref</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}& <span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}\\ \mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}& \mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dref</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; qref</span>}}\end{array}\right]$

Fig. 5 is a schematic diagram of signals of the permanent magnet synchronous motor rotor position sensor used in the present invention. The rotor position signal includes three commutation Hall signals HALLa, HALLb and HALLc and two position Hall signals QEP1 and QEP2. Within the 360° range of each commutation Hall signal, 180° is high level, and the other 180° is low level. The relationship can determine the position interval of the motor rotor and the absolute base position of the motor rotor. Only after the motor is running, two orthogonal position Hall signals will be sent out. Each position Hall signal contains 24 rising and falling edges in the range of 360°, and the two paths contain 48 rising and falling edges in total, that is, each time The occurrence of a rising or falling edge indicates that the motor rotor has changed by 7.5°.

The present invention includes four parts for calculating the motor rotor position signal: the determination of the initial rotation angle of the motor rotor position, the determination of the absolute base position of the motor rotor, the calculation of the absolute position of the motor rotor and the verification of the absolute position of the motor rotor.

Fig. 6 is a schematic diagram of logic for judging the initial value of the motor rotor position in the calculation of the motor rotor position signal according to the present invention. Through the relationship between the high and low levels of the three-way commutation Hall signal, the position interval of the motor rotor within the range of 60° can be determined, and the middle position of this interval is set as the initial rotation angle of the motor rotor, and the permanent magnet synchronous motor is driven to start .

Fig. 7 is a schematic diagram of the flow chart of determining the absolute base position of the motor rotor in the calculation of the motor rotor position signal in the present invention. After the permanent magnet synchronous motor is started, according to Figure 5, when the rising and falling edges of HALLa are detected, and HALLb is at a high level, the absolute base position of the motor rotor is determined to be 180°; if HALLb is at a low level, the absolute base position of the motor rotor is determined The position is 0°; when the rising and falling edges of HALLb are detected and HALLc is high level, the absolute base position of the motor rotor is determined to be 300°; if HALLc is low level, the absolute base position of the motor rotor is determined to be 120°; The rising and falling edges of HALLc, and HALLa is high level, determine the absolute base position of the motor rotor as 60°, if HALLa is low level, determine the absolute base position of the motor rotor as 240°. That is, by detecting the rising and falling edges of the three commutation Hall signals, the absolute base position of the motor rotor can be determined, and the initial NUMBER value is ANGLE_BASE/7.5.

After the absolute base position of the motor rotor is determined, the absolute position of the motor rotor at any time can be calculated through the quadrature signal sent by the motor position Hall sensor. The rising edge and falling edge of the two position Hall signals can be collected through the main control chip. Set the counting variable NUMBER. When the motor rotor rotates counterclockwise and the two position Hall signals have a rising or falling edge change, NUMBER is incremented by 1; when the motor rotor rotates clockwise, the two position Hall signals have a rising or falling edge. , the NUMBER is decremented by 1. Therefore, by detecting the rising and falling edges of the two commutation Hall signals, the absolute position of the permanent magnet synchronous motor rotor can be determined as NUMBER*7.5 with an accuracy of 7.5°.

While calculating the absolute position of the rotor of the permanent magnet synchronous motor, the absolute position of the rotor of the permanent magnet synchronous motor is verified. Referring to Figure 7, continuously detect the rising and falling edges of the three commutation Hall signals to determine the position of the motor rotor at the moment when the rising and falling edges of the commutation Hall signals occur. If it is the same as the calculated absolute position of the motor rotor, it proves that the calculated The absolute position of the rotor of the motor is correct; otherwise, the rotor position of the motor obtained through the rising and falling edges of the three-way commutation Hall signal is used to replace the calculated absolute position of the rotor of the permanent magnet synchronous motor.

Fig. 8 is a schematic diagram of the SENT signal of the torque rotation angle sensor used in the present invention. The length of each Message cycle of the signal is 513 microseconds, including 1 synchronization segment (Synchronization), 8 Nibble segments (Nibble) and 1 pause segment (Pause). The 8 Nibble segments include 1 status segment (Nibble1), 6 data segments (Nibble2-Nibble7), and 1 CRC check segment (Nibble8). Each Nibble represents a hexadecimal number, that is, a four-digit binary number, and its time length is 12 to 27 sending unit clock cycles, and is used to represent 0 to 15 of the hexadecimal number. The time length of the synchronization segment is 56 clock cycles of the sending unit. The status segment is Nibble1, which should be expressed as a four-digit binary number, the lower two digits indicate whether the sensor is working normally, and the upper two digits are reserved. There are 6 Nibbles in the data segment, where Nibble2, Nibble3 and Nibble4 represent Signal1, and Nibble5, Nibble6 and Nibble7 represent Signal2. Each Signal is a 12-bit binary number composed of 3 Nibbles, which are divided into three parts: the most important, the medium important and the least important. For Signal1, Nibble2 is the highest 4 bits, Nibble3 is the middle 4 bits, and Nibble4 is the lower 4 bits. For Signal2, Nibble7 is the highest 4 bits, Nibble6 is the middle 4 bits, and Nibble5 is the lower 4 bits. The CRC check section is Nibble8, and the data section is checked through cyclic redundancy. The pause segment is used to make up time so that each frame of Message reaches its period. There are two such SENT signals, namely SENTA and SENTB, each of which can calculate the twisting angle of the upper and lower ends of the torsion bar. These two signals are redundant signals and can be checked against each other.

Fig. 9 is a schematic diagram of the PWM signal of the torque angle sensor used in the present invention. The period of the PWM-like signal is 6 milliseconds, the high level accounts for 12.5% to 87.5% of the entire period, and the angle value represented by it is 0° to 296°.

The invention solves the steering wheel torque angle sensor signal, including four parts: SENT signal acquisition, SENT signal resolution, PWM-like signal acquisition and PWM-like signal resolution.

Fig. 10 is a schematic diagram of the SENT signal acquisition process of the present invention. The SENT signal acquisition adopts the method of triggering the interruption of the main control chip. The main control chip detects the falling edge of the SENT signal, and records the time when the falling edge occurs, and then triggers an interrupt. First, the time interval between the two falling edges must be calculated. If the clock cycle of the sending unit is around 56, it is determined that this One segment is a synchronous segment and calculates the actual sending unit clock period. After the synchronization segment is determined, the segments that trigger the interrupt again representing the SENT signal are Nibble1 to Nibble8 in sequence. Divide the time length of each segment from Nibble1 to Nibble8 by the clock cycle of the sending unit, and after rounding, the number of clock cycles of the sending unit contained in each Nibble is obtained, which should be between 12 and 27, representing hexadecimal Count from 0 to 15.

Fig. 11 is a schematic diagram of a flow chart of SENT signal calculation in the present invention. When solving the SENT signal, first judge whether the sensor is working normally, then perform CRC check on the SENT signal, and finally use Nibble2 as the upper 4 bits, Nibble3 as the middle 4 bits, and Nibble4 as the lower 4 bits to form a 12-bit binary number Signal1. Nibble7 is the upper 4 bits, Nibble6 is the middle 4 bits, and Nibble5 is the lower 4 bits, forming a 12-bit binary number Signal2. Through Signal1 and Signal2, the angle difference between the upper and lower ends of the torsion bar can be calculated. In the schematic diagram of the SENT signal acquisition and solution process, NibbleB is a buffered array. In the SENT signal acquisition process, NibbleA is assigned to NibbleB, and in the solution process, NibbleB is assigned to NibbleC. This can ensure the SENT signal acquisition process and SENT signal solution. The calculation process does not affect each other. The angle difference between the upper and lower ends of the torsion bar calculated by SENTA and SENTB cannot exceed 0.375°, otherwise the sensor is considered to be abnormal.

Fig. 12 is a schematic diagram of the process of collecting PWM-like signals in the present invention. After the main control chip collects the rising and falling edges of the PWM-like signal, it will record the time when it occurs, and then trigger an interrupt. First, it needs to calculate the time interval between the two rising and falling edges, and then read the level of the PWM-like signal at this time. If the signal collected at this time is low level, the calculated time interval is the duration of the high level, otherwise it is the duration of the low level.

Fig. 13 is a schematic diagram of the calculation process of the PWM-like signal in the present invention. This value is linearly converted from 0° to 296° by the percentage of a cycle that is high. In the SENT signal, Signa11 is the position signal of the steering wheel end of the torsion bar, which is 0° to 40°. The value obtained from the PWM-like signal is 0° to 296°. The steering wheel rotation angle can be calculated from -740° to 740° through the vernier algorithm. It can meet the angle range of two positive and negative rotations of the steering wheel.

Claims (7)

1. An electric power steering system controller based on a permanent magnet synchronous motor, characterized in that the controller has a main control chip, and the controller includes a motor rotor position signal acquisition circuit, a steering wheel torque angle signal acquisition circuit, a permanent The magnetic synchronous motor drive circuit and CAN communication circuit, the motor rotor position signal and the steering wheel torque angle signal are all connected to the main control chip through the RC filter circuit and the two reverse circuits composed of Schmitt triggers, and the drive signal is from After the main control is sent out, it passes through the bus transceiver 74HC245, the driver chip IR2130 and the driver circuit in turn. The high-side switch signal is boosted by the bootstrap circuit after passing through the driver chip. After RC filtering and operational amplifier circuit, it enters the main control chip, and performs current feedback control on the permanent magnet synchronous motor, and adds a CAN communication transceiver between the CAN bus and the main control chip; in the electric power steering system based on the permanent magnet synchronous motor When the controller performs back-to-back control, the maximum and minimum values of the back-to-back current are limited at different vehicle speeds V; NibbleA is assigned to NibbleB in the SENT signal acquisition process, and NibbleB is assigned to NibbleC in the solution process. The angle difference between the upper and lower ends of the torsion bar calculated by SENTA and SENTB cannot exceed 0.375°, otherwise the sensor is considered to be abnormal. 2. The electric power steering system controller according to claim 1, wherein the main control chip is a digital signal processor TMS320F2812 produced by Texas Instruments. 3. An electric power steering system control method based on a permanent magnet synchronous motor, characterized in that the motor rotor position signal and the steering wheel torque angle signal are collected and calculated, and the electric power steering control method and the permanent magnet synchronous motor control method To obtain the drive signal, the control method includes four parts: electric power steering control, permanent magnet synchronous motor control, motor rotor position signal calculation and steering wheel torque angle signal calculation; NibbleA is assigned to NibbleB in the SENT signal acquisition process, NibbleB is assigned to NibbleC in the calculation process, and the angle difference between the upper and lower ends of the torsion bar calculated by SENTA and SENTB cannot exceed 0.375°, otherwise the sensor is considered to be abnormal. 4. The electric power steering system control method based on a permanent magnet synchronous motor according to claim 3, wherein said electric power steering control includes basic power assist control, motor compensation control and return control, and said The basic power assist control adopts a multi-point broken line basic power assist curve. The vehicle speed is divided into multiple different intervals through the vehicle speed signal. Each speed interval selects a number of characteristic points corresponding to the basic assist current of the motor from the steering wheel torque, and connects the characteristic points to form The multi-point broken line of the vehicle speed range; the motor compensation control includes three parts: friction compensation control, damping compensation control and inertia compensation control; the return to center control includes two parts: return to center judgment and return to center current control. 5. According to the control method of electric power steering system based on permanent magnet synchronous motor according to claim 3, it is characterized in that, the described permanent magnet synchronous motor control method adopts vector control in which the excitation direction current of the motor is equal to zero, and through the space pulse The wide vector modulation method and the seven-segment method generate switching signals for switching devices. 6. The electric power steering system control method based on a permanent magnet synchronous motor according to claim 3, wherein the permanent magnet synchronous motor control method performs three-way commutation Hall signals and two-way position Hall signals Acquisition and calculation to obtain the rotor position of the permanent magnet synchronous motor, which includes four parts: the determination of the initial rotation angle of the motor rotor position, the determination of the absolute base position of the motor rotor, the calculation of the absolute position of the motor rotor and the calibration of the absolute position of the motor rotor test. 7. according to the electric power steering system control method based on permanent magnet synchronous motor according to claim 3, it is characterized in that, described permanent magnet synchronous motor control method carries out collection and solution to two-way SENT signal and one-way class PWM signal, obtains Steering wheel torque angle information, which includes four parts: SENT signal acquisition, SENT signal calculation, PWM-like signal acquisition and PWM-like signal calculation.