CN2934008Y - Vehicle Electric Power Steering Controller - Google Patents

Abstract

The utility model relates to a vehicle electric assisted power steering controller, which comprises a microprocessor, an H-bridge motor driving module, a motor, a current sample and feedback resistance and an electronic servo module. The microprocessor is connected with a digital potentiometer through SPI bus; the motor driving signal output end of the electronic servo module is connected with the H-bridge motor driving module. The utility model has the advantages of that feedback electric pressure signal is provided by the electronic servo module to the current sample and feedback resistance, and that given electric pressure signal is provided by differential circuit. The double directional detection provides real motor current situations through the current sample and feedback resistance and avoids the relatively large differences between the feedback current and the real current caused by fly-wheel diode in the H-bridge circuit. The electric assisted power can better satisfy practical needs and the better steadiness of the assisted power steering controller gives drivers hand feeling.

Description

Vehicle Electric Power Steering Controller

technical field

The utility model relates to a vehicle electric power steering controller, which is especially suitable for a steering column type electric servo power steering system of a small vehicle.

Background technique

At present, with people's increasing requirements for vehicle handling stability, environmental protection, and energy saving, traditional hydraulic power steering systems are gradually being replaced by electric power steering systems. The electric power steering can adjust the magnitude of the power assist according to different vehicle speeds and the driver's hand strength through the preset power assist characteristic curve to meet different driving conditions. For an automotive electronic product, its electronic control unit (ECU) part is one of the key points of the whole product, and it is also one of the difficulties. Improper design of the hardware circuit of the ECU will not only increase the complexity of the structure and increase the cost of the entire product, but also affect the stability and accuracy of the motor assist, making the driver's feel worse and affecting the vehicle's handling stability.

At present, a general electric power steering device for automobiles includes a microprocessor, an H-bridge motor drive module, a motor, and a resistor for sampling the feedback current. The motor is usually controlled by an H-bridge drive circuit. By selecting the conduction and disconnection of different MOSFET tubes To control the rotation direction of the motor, the power assist of the motor is controlled by adjusting the duty cycle of the pulse width modulation signal (PWM); at the same time, the voltage value proportional to the motor current is fed back to the microprocessor through the sampling resistor at the high end of the H bridge , the feedback current is obtained according to the ratio of the feedback voltage and compared with the given current set by the microprocessor, and the proportional differential (PI) or proportional differential integral (PID) control regulator integrated in the microprocessor is used for regulation, and the output The pulse width modulation signal is sent to the motor drive circuit to drive the motor to generate corresponding power assistance. Under normal circumstances, this feedback voltage can accurately reflect the current value of the motor; but when the driver turns the steering wheel quickly, due to the effect of the freewheeling diode, the feedback current corresponding to the feedback voltage will be different from the actual motor current. The large discrepancy makes the motor power assistance not meet the actual requirements. At the same time, according to the structural characteristics of the H-bridge, the feedback voltage is positive regardless of whether the motor is rotating forward or reverse, so that when the driver turns the steering wheel to pass through the zero point, there will be a sense of discontinuity. The above problems will make the driver's feel worse, and even affect the handling stability in some cases.

Contents of the invention

The purpose of the utility model is to provide a driver with a good steering feel and a stable and reliable vehicle electric power steering controller.

The vehicle electric power steering controller of the utility model includes a microprocessor, an H-bridge motor drive module, a motor, a resistor for sampling feedback current and an electronic servo module. The electronic servo module includes a digital potentiometer, a sampling resistor, an adapter Resistor, first power amplifying element, second power amplifying element and pulse width modulation controller, wherein the digital potentiometer, sampling resistor and matching resistor are connected in series, and the two ends of the series circuit are connected with the main and auxiliary torque signal output of the torque sensor respectively The input end of the first power amplifying element is connected with both ends of the sampling resistor, the output end of the first power amplifying element is connected with the pulse width modulation controller, and the input end of the second power amplifying element is connected with the sampling feedback current resistor The two ends are connected together, the output end of the second power amplifying element is connected with the pulse width modulation controller, the microprocessor is connected with the digital potentiometer through the SPI bus, and the motor drive signal output end of the electronic servo module is connected with the H-bridge motor drive module.

The working principle of the vehicle electric power steering controller is as follows:

Input the vehicle speed signal, engine ignition signal and motor current signal of the microprocessor, and output three SPI bus signals through the internal program control of the microprocessor - data signal DAT, clock signal CLK and chip select signal CS, these three bus signals are controlled It is used to change the resistance value of the digital potentiometer to indirectly adjust the output voltage at both ends of the sampling resistor. After adding the main and auxiliary torque input voltages of the torque sensor to the two ends of the series circuit of the digital potentiometer, the matching resistor and the sampling resistor respectively, a series differential circuit is formed. When the resistance of the matching resistor and the sampling resistor is zero, the voltage across the sampling resistor is equal to the real torque voltage. When the vehicle speed increases, the resistance value of the digital potentiometer is adjusted according to the preset ratio of the microprocessor, so that the voltage at both ends of the sampling resistor is smaller than the voltage signal output by the real torque sensor, so as to achieve the purpose of reducing the power assist as the vehicle speed increases. The output voltage at both ends of the sampling resistor is amplified and directly input to the pulse width modulation controller, and the pulse width modulation controller generates and controls the driving of the H-bridge drive module according to the amplified sampling resistor voltage and the feedback voltage reflecting the motor current. pulse width modulated signal. The H-bridge motor drive module can control the rotation direction and output torque of the motor according to the output signal of the pulse width modulation controller.

The beneficial effects of the utility model are:

The utility model adopts the electronic servo module to carry out two-way detection on the feedback voltage signal provided by the sampling feedback current resistance and the given voltage signal provided by the differential circuit, so that the sampling feedback current resistance can truly reflect the current situation of the motor, and effectively avoid the problem caused by the H bridge circuit. The defect that the feedback current caused by the freewheeling diode in the motor has a large deviation from the actual motor current makes the motor assist more meet the actual needs. Therefore, the electric power steering controller after the introduction of the electronic servo module is more stable than the general power steering controller, and can provide the driver with a better feel.

Description of drawings

FIG. 1 is a schematic diagram of a vehicle electric power steering controller;

Fig. 2 is a specific circuit example of a vehicle electric power steering controller.

Detailed ways

Further illustrate the utility model below in conjunction with accompanying drawing.

With reference to Fig. 1, vehicle electric power steering controller comprises microprocessor 4, H-bridge motor drive module 11, motor 12, the resistance 13 of sampling feedback current and electronic servo module 8, said electronic servo module 8 comprises digital potentiometer 14 , sampling resistor 15, adapting resistor 16, first power amplifying element 17, second power amplifying element 18 and pulse width modulation controller 19, wherein digital potentiometer 14, sampling resistor 15 and adapting resistor 16 are connected in series, the series circuit The two ends of the torque sensor are respectively connected with the main and secondary torque signal output ends of the torque sensor, the input end of the first power amplifying element 17 is connected with the two ends of the sampling resistor 15, the output end of the first power amplifying element 17 is connected with the pulse width modulation control 19 is connected, the input end of the second power amplification element 18 is connected with the resistor 13 two ends of the sampling feedback current, the output end of the second power amplification element 18 is connected with the pulse width modulation controller 19, and the microprocessor 4 passes the SPI bus 5 is connected to the digital potentiometer 14, and the motor drive signal output end of the electronic servo module 8 is connected to the H-bridge motor drive module 11.

The role of the microprocessor is to correct the power boost according to the vehicle speed, provide protection for the comprehensive performance of the entire electric servo power steering controller, provide failure analysis, and ensure the normal operation of the system. Its input signals include vehicle speed signal, engine ignition signal, and motor current signal. Among them, the vehicle speed signal is the basis for correcting the power boost, the engine ignition signal is required for starting self-test, and the motor current signal is used to monitor the working state of the motor. The output signal is connected to the electronic servo module 8 through the SPI bus 5 to adjust the resistance value of the digital potentiometer 14 in the electronic servo module, and to correct the power boost according to the vehicle speed. The SPI bus includes three signals, namely data signal DAT, clock signal CLK and chip select signal CS.

The input signals of the electronic servo module include the SPI bus input signal, the main torque signal and auxiliary torque signal output by the torque sensor, and the voltage signal at both ends of the sampling feedback current resistor 13 . The voltage of the sampling resistor 15 and the feedback voltage reflecting the motor current are respectively amplified by the first power amplifying element 17 and the second power amplifying element 18 and enter the pulse width modulation controller 19. The output signal of the pulse width modulation controller 19 is to control the H-bridge motor drive The four pulse width modulation output signals 9 of the module 11.

The two ends of the series circuit of the digital potentiometer 14, the matching resistor 15 and the sampling resistor 16 are respectively applied with the main and auxiliary torque input voltages of the torque sensor to form a differential circuit. In this way, when the digital potentiometer is zero, the voltage across the sampling resistor is equal to the real torque voltage. When the vehicle speed increases, the resistance value of the digital potentiometer is adjusted according to the preset ratio of the microprocessor, so that the voltage across the sampling resistor is smaller than the real torque voltage, and the purpose of reducing the power steering as the vehicle speed increases can be achieved.

The sampling feedback current resistor is connected in series with the motor, and the current flowing through it is the motor current, so that the current sampling resistor can truly reflect the current situation of the motor. At the same time, such a circuit can provide bidirectional current detection to the electronic servo module, so as to truly reflect the motor assisting situation .

In the specific circuit shown in Fig. 2, the digital potentiometer 14 in the electronic servo module is a 256-bit SPI electronic potentiometer whose model is AD5160. The pulse width modulation controller 19 is NCV494. The H-bridge motor drive module is composed of 4 field effect transistors NTP60N06.

Claims (3)

1, the vehicle electric booster steering controller, comprise microprocessor (4), H bridge motor drive module (11), motor (12), the resistance of sampling feedback electric current (13), it is characterized in that also comprising electron servo module (8), said electron servo module (8) comprises digital regulation resistance (14), sample resistance (15), adaptive resistance (16), first power amplification element (17), second power amplification element (18) and PDM keyer (19), digital regulation resistance (14) wherein, sample resistance (15) and adaptive resistance (16) series connection, the two ends of this circuit series respectively with the master of torque sensor, the accessory torque signal output part links to each other, the two ends of the input end of first power amplification element (17) and sample resistance (15) connect altogether, the mouth of first power amplification element (17) links to each other with PDM keyer (19), resistance (13) two ends of the input end of second power amplification element (18) and sampling feedback electric current connect altogether, the mouth of second power amplification element (18) links to each other with PDM keyer (19), microprocessor (4) links to each other with digital regulation resistance (14) by spi bus (5), and the motor drive signal mouth of electron servo module (8) connects H bridge motor drive module (11).

2. vehicle electric booster steering controller according to claim 1 is characterized in that PDM keyer (19) is NCV494.

3. vehicle electric booster steering controller according to claim 1 is characterized in that said digital regulation resistance (14) is that model is 256 SPI electronic potentiometers of AD5160.