JPH08258733A - Electric power steering controller - Google Patents

Abstract

PURPOSE: To provide an electric power steering controller in which an outside wiring can be reduced, and also travelling state detecting means can be reduced so that a cost can be reduced. CONSTITUTION: An alternator pulsation detector circuit 14 and an electric power supply circuit 10 which selectively controls main electric power supply or back-up electric power supply so as to apply it to a control circuit, are arranged in a controller C. While, in a control circuit 2, an engine speed is operated from the pulsating frequency of an alternator 13, and also the electric circuit 10 is actuated when this engine speed becomes over a predetermined value so that the main electric power supply is applied to the control circuit 2, and back up voltage is applied thereto when the engine speed becomes below the predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering controller for driving an electric motor to obtain a power assist force.

[0002]

2. Description of the Related Art FIG. 4 shows a circuit diagram of a conventional electric power steering controller. The controller C is for controlling the electric motor m, and is connected to the battery B, which is a power source for driving the electric motor m, via the drive wiring 9. An alternator 13 is connected to the battery B. The alternator 13 is an AC generator that is connected to an engine (not shown) and has a rectifying function that operates by the rotation of the engine. further,
Controller wiring 1 branched from the driving wiring 9
1 is connected to the power supply circuit 10 provided in the controller C via the ignition switch IG. The backup wiring 12 is directly connected to the power supply circuit 10 without the ignition switch IG.
The power supply circuit 10 as described above has a function of applying the main voltage to the control circuit 2 when the ignition switch IG is on, and applying only the backup voltage when the ignition switch IG is off. Then, this backup voltage is for supplying the necessary backup current to the controller C and holding the memory of the controller even when the ignition switch IG is off. Further, the controller C includes a torque sensor 3,
The vehicle speed sensor 4 and the engine rotation sensor 5 are connected.

The controller C mainly comprises a drive circuit 1 for controlling the voltage applied to the electric motor m and a control circuit 2 for controlling the drive circuit 1. The drive wiring 9 is connected to the drive circuit 1 in the controller C, while connecting the electric motor m to the drive circuit 1. In addition, the control circuit 2 that controls the drive circuit 1 includes a power supply circuit 10
Connect to. On the other hand, the torque sensor 3, the vehicle speed sensor 4, and the engine rotation sensor 5 are respectively connected to the interface 6,
It is connected to the control circuit 2 via 7 and 8. The torque sensor 3 is for detecting the steering torque input to the steering wheel, and the vehicle speed sensor 4 is for detecting the vehicle speed. Then, according to the detected steering torque and vehicle speed, the control circuit 2 operates the drive circuit 1, and the drive circuit 1 changes the voltage applied to the electric motor m. The engine speed sensor 5 senses the engine speed. For example, while the ignition switch IG is on, the power supply circuit 10 is operated when the engine speed is low or in a stopped state to control the control circuit. By applying only the backup voltage to 2, the system as the electric power steering device is stopped, and at the same time, the battery consumption is suppressed and the battery B is prevented from rising.

[0004]

In the above-mentioned conventional electric power steering control device, the battery B is used not only as a power source for driving the electric motor m but also as a power source for the controller C. And controller C
The on / off of is linked with the ignition switch IG for starting the engine, and when the engine is started,
A main voltage is applied to the control circuit 2 to control the electric power steering device. However, since the on / off of the controller C is interlocked with the ignition switch IG in this way, the controller wiring 11 has to be external wiring, which increases the cost accordingly and when mounting it in the vehicle. A certain amount of space is required. Further, to the control circuit 2 of the controller C, three systems of a torque sensor 3, a vehicle speed sensor 4, and an engine rotation sensor 5 are connected as a traveling state detecting means. Therefore, members such as wiring and interfaces for three systems are required, and even in this amount, there is a factor of cost increase. An object of the present invention is to provide an electric power steering control device capable of reducing the cost by reducing the external wiring and the traveling state detecting means.

[0005]

The present invention relates to an electric motor for applying a steering assist force, a controller for controlling the electric motor, a battery connected to the electric motor and the controller, an engine, and the battery. An alternator connected, and a running state detecting means connected to the controller, the controller is connected to the drive circuit for changing the voltage applied to the electric motor, the running state detecting means, depending on the running state It is premised on an electric power steering control device composed of a control circuit for controlling a drive circuit. While assuming the above device, the first invention, in the controller, an alternator pulsation detection circuit and a power supply circuit for selectively controlling the main voltage or the backup voltage to apply to the control circuit, while the control circuit, When calculating the engine speed from the pulsating frequency of the alternator, and when this engine speed exceeds the set value,
It is characterized in that the power supply circuit is operated to apply the main voltage to the control circuit, and the backup voltage is applied when the voltage is below the set value. According to a second aspect of the present invention, the control circuit calculates the engine speed from the pulsation of the alternator and, based on the calculated value, determines whether to apply the backup voltage or the main voltage, and necessary information. A memory unit that stores the data and a control unit that controls the drive circuit according to the running state.When the backup voltage is applied, only the arithmetic unit and the memory unit operate, and when the main voltage is applied, In addition to the arithmetic unit and the memory unit, the control unit is also operated. A third aspect of the invention is characterized in that only a torque sensor is provided as the traveling state detecting means, and the control circuit estimates the vehicle speed and the engine rotation from the alternator pulsation.

[0006]

In the first aspect of the present invention, the alternator pulsation detection circuit detects the pulsation of the alternator, and the control circuit estimates the engine speed based on the pulsation frequency. Further, the control circuit operates the power supply circuit to apply the main voltage to the control circuit when the engine speed becomes equal to or higher than the set value, and activates the system as the electric power steering device. At other times, only the backup voltage is applied to stop the system as the electric power steering device. In the second aspect, when the backup voltage is applied, the arithmetic unit and the memory unit operate, and the control unit does not operate. On the other hand, when the main voltage is applied, the control unit operates in addition to the arithmetic unit and the memory unit, so that the system as the electric power steering device can be activated.
In the third invention, the engine speed and the vehicle speed are estimated by the pulsation frequency detected by the alternator pulsation detection circuit, the electric motor is controlled according to the conditions including the steering torque, and the optimum power assist force is always provided. Let it work.

[0007]

1 and 2 show a first embodiment of an electric power steering controller of the present invention. The controller C of the first embodiment is provided with an alternator pulsation detection circuit 14,
The detection circuit 14 detects the pulsation of the alternator 13. That is, the alternator 13 generates AC electricity according to the rotation of the engine, and rectifies and outputs the AC electricity. The frequency of AC electricity at this time is proportional to the engine speed. Therefore, the pulsating frequency of the rectified direct current is also proportional to the engine speed as shown in FIG. The pulsation signal thus detected by the alternator detection circuit 14 is input to the control circuit 2. The control circuit 2 calculates the engine speed based on this pulsation frequency. The engine speed can be calculated from the following equation. N = a ・ Ω / b ・ c However, N: Estimated engine speed (rpm) Ω: Alternator pulsation frequency (HZ) a: Constant b: Alternator pulsation coefficient (pulsation number generated per alternator rotation) c: Plea ratio (Ratio of engine speed to alternator speed) Since the engine speed is also proportional to the vehicle speed, the control circuit 2 also calculates the vehicle speed from the pulsation frequency.

Further, the controller C controls the power supply circuit 10 based on the above calculation result. The power supply circuit 10 is connected to the battery B and the alternator 13 via the wiring 15 connected to the drive circuit 1. Then, it has a function of selectively controlling the main voltage or the backup voltage and applying it to the control circuit. That is, if the engine speed as a result of calculation by the control circuit 2 is less than or equal to the set value, the power supply circuit 10 operates by receiving a signal from the control circuit 2 and applies only the backup voltage to the control circuit 2. . Then, the voltage applied from the drive circuit 1 to the electric motor m is stopped, and only the necessary information up to that point is stored. On the contrary, if the number of rotations is higher than the set value,
The power supply circuit 10 operates in response to the signal from the control circuit 2,
The main voltage is applied to the control circuit 2. Then, the system as the electric power steering device is activated, and necessary power assist can be obtained. As described above, in this embodiment, whether or not the engine is started is detected by the pulsation of the voltage, and the engine speed and the vehicle speed of the engine are calculated by the pulsation, and the ignition switch IG and the conventional ignition switch IG are used. The controller C does not need to be linked, and the vehicle speed sensor 4 and the engine rotation sensor 5
Is also unnecessary. The power supply for the control circuit 2 is guided by using the wiring 15 connected to the drive circuit 1, and other configurations are the same as those of the conventional one.

Next, the operation of the electric power steering controller of this embodiment will be described. First, when the engine is not running, the pulsation of the output voltage of the alternator 13 becomes zero. At this time, the power supply circuit 10 operates based on the output signal from the control circuit 2 to apply only the backup voltage to the control circuit 2. In other words, when the engine is stopped, the control circuit 2 stops the system as the electric power steering device in order to suppress unnecessary power consumption. At this time, the backup power supply for holding only the necessary information in the control circuit 2 is supplied from the power supply circuit 10. When the engine is started, the alternator pulsation detection circuit 14 detects the pulsation of the alternator, and the control circuit 2 calculates the engine speed, the vehicle speed, and the like. Then, if the engine speed at this time is less than or equal to the set value, only the backup voltage is applied to the control circuit 2 in order to stop the system as the electric power steering device. However,
In this embodiment, the set value of the engine speed is set to about 400 rpm, and if it is less than 400 rpm, it is determined that the engine is stopped. Therefore, when the engine is on the verge of stopping or the engine is stopped despite the ignition switch IG being on, the voltage applied to the control circuit 2 does not require the system as the electric power steering device to start. Since only the backup voltage is determined, the power consumption is reduced and the energy loss is reduced accordingly.

When the engine speed exceeds the set value, the power supply circuit 10 operates based on the signal from the control circuit 2,
The main voltage is applied to the control circuit 2. Based on this main voltage, the control circuit 2 activates the system as the electric power steering device, which is as follows. That is, the torque sensor 3 detects the steering torque, the engine speed is estimated from the pulsation of the alternator 13, and the vehicle speed is estimated from the estimated engine speed. Then, the control circuit 2 controls the drive circuit 1 according to the traveling state, and the drive circuit 1 controls the voltage applied to the electric motor m to assist the steering force.

The second embodiment shown in FIG. 3 shows an example of the control circuit 2 of the controller C. The other configurations are the same as those in the first embodiment, and detailed description thereof will be omitted. In the second embodiment, the control circuit 2
And an arithmetic unit 16 that calculates the engine speed from the pulsation of the alternator and determines whether to apply the backup voltage or the main voltage based on the calculated value.
A memory unit 17 that stores necessary information, a CPU, and the like, and a control unit 18 that controls the drive circuit 1 in accordance with a running state. The calculation unit 16 is connected to the alternator pulsation detection circuit 14 and calculates the engine speed from the pulsation frequency detected there. In addition, since the method of this calculation has already been explained,
Here, it is omitted. Then, the calculation unit 16 outputs a signal according to the calculated engine speed to the power supply circuit 10. The power supply circuit 10 is switching-controlled, for example, according to the signal from this operation part, and applies the main voltage or the backup voltage to the control circuit 2.

For example, if the engine speed is less than the set value (eg 400 rpm), the power supply circuit 10 applies only the backup voltage to the memory section 17 of the control circuit 2. Then, with this backup voltage, the memory section 17 stores necessary information. Even at this time, the calculation unit 16
Calculates the engine speed from the pulsating frequency of the alternator. On the other hand, when the engine speed becomes equal to or higher than the set value, the power supply circuit 10 applies the main voltage to the control unit 18 based on the signal from the calculation unit 16. Then, the control unit 18 is turned on by this main voltage to activate the system as the electric power steering device. It should be noted that even when the main voltage is applied, the memory unit 17 and the arithmetic unit 16 operate to store necessary information and calculate the engine speed from the pulsating frequency of the alternator.

[0013]

According to the first and second aspects of the present invention, the external wiring for connecting to the ignition switch can be eliminated, and the cost and space can be saved accordingly. Further, when the engine speed is equal to or lower than the set value, it is determined that the system as the electric power steering device does not need to be activated, and only the backup voltage is applied to the control circuit, so that the power consumption is reduced. As a matter of course, as the power consumption decreases, the energy loss also decreases. According to the third aspect of the present invention, only the torque sensor needs to be provided as the traveling state detecting means, and the vehicle speed sensor and the engine rotation sensitizer, which are required in the prior art, are not required, and further cost reduction can be achieved. .

[Brief description of drawings]

FIG. 1 is a circuit diagram of an electric power steering controller according to a first embodiment of the present invention.

FIG. 2 is a graph showing pulsation characteristics of an alternator.

FIG. 3 is a diagram showing a control circuit 2 in the electric power steering controller of the second embodiment.

FIG. 4 is a circuit diagram of a conventional electric power steering control device.

[Explanation of symbols]

 1 Drive Circuit 2 Control Circuit 3 Torque Sensor 10 Power Supply Circuit 13 Alternator 14 Alternator Pulsation Detection Circuit 16 Arithmetic Section 17 Memory Section 18 Control Section C Controller B Battery m Electric Motor

Claims (3)

[Claims] 1. An electric motor for applying a steering assist force, a controller for controlling the electric motor, a battery connected to the electric motor and the controller, an alternator connected to the engine and connected to the battery, and the controller. A driving circuit for changing the voltage applied to the electric motor, and a control circuit for controlling the driving circuit according to the running state, the driving circuit including the connected running state detecting means, and the driving circuit for changing the voltage applied to the electric motor. In the electric power steering control device composed of, in the controller, an alternator pulsation detection circuit and a power supply circuit for selectively controlling the main voltage or the backup voltage and applying it to the control circuit are provided, while the control circuit is the alternator Calculate engine speed from pulsation frequency In addition, when the engine speed exceeds a set value, the power supply circuit is operated to apply the main voltage to the control circuit, and when the engine speed is below the set value, the backup voltage is applied. Electric power steering control device. 2. The control circuit calculates the engine speed from the pulsation of the alternator, and based on the calculated value, calculates a backup voltage or a main voltage, and a necessary information. It consists of a memory unit for storing and a control unit for controlling the drive circuit according to the running state.When the backup voltage is applied, only the arithmetic unit and the memory unit are activated, and when the main voltage is applied, The electric power steering control device according to claim 1, wherein a control unit is further operated in addition to the arithmetic unit and the memory unit. 3. The electric power steering control device according to claim 1, wherein only the torque sensor is provided as the traveling state detecting means, and the control circuit estimates the vehicle speed and the engine rotation from the pulsating frequency of the alternator.