KR100352359B1 - An electric-power-steering controller - Google Patents

Abstract

A relay 46 for output control of the drive current from the battery 41 to the large current load 40, and a smoothing capacitor 42 and a relay connected between the connection side of the large current load 40 and the earth of the relay 46; The preliminary charging circuit 60 is provided for closing the contact of the relay 46 after charging the capacitor 42 with a charge during the predetermined time before closing the contact of 46.

Description

An electric-power-steering controller

An electric power steering control device will be described as an example of a conventional device of a vehicle control device. Fig. 4 is a circuit diagram showing, in part, a block diagram of a conventional electric power steering control device disclosed in Japanese Patent Application No. Hei 5-64268. In the drawings, reference numeral 4O denotes a steering wheel of a vehicle (not shown). (Not shown) denotes a battery for supplying a motor current IM for driving the motor 40.

Reference numeral 42 denotes a capacitor of a large capacity (about 1000 μF to 3600 μF) for absorbing the ripple component of the motor current IM, reference numeral 43 denotes a shunt resistor for detecting the motor current IM, and reference numeral 44 denotes a motor. It is a bridge circuit composed of a plurality of semiconductor switching elements (for example, FETs) Q1 to Q4 for switching the current IM in accordance with the magnitude and direction of the auxiliary torque. "46" denotes an always open relay for interrupting energization of the motor current IM as necessary.

Reference numeral 47 denotes a driving circuit for driving the motor 40 through the bridge circuit 44 and at the same time driving the relay 46, and reference numeral 48 denotes a motor current IM through one end of the shunt resistor 43. Motor current detecting means for detecting a, and the driving circuit 47 and the motor current detecting means 48 constitute peripheral circuit elements of a microcomputer, which will be described later.

Reference numeral 50 denotes a torque sensor for detecting steering torque T of the steering wheel, and reference numeral 51 denotes a vehicle speed sensor for detecting a vehicle speed V of the vehicle.

Reference numeral 55 denotes a microcomputer ECU that calculates an auxiliary torque based on the steering torque T and the vehicle speed V, and simultaneously feeds back the motor current IM to generate a drive signal corresponding to the auxiliary torque. The rotation direction command D ₀ and the current control amount I ₀ for controlling the circuit 44 are input to the drive circuit 47 as a drive signal.

The microcomputer 55 includes motor current determining means 56 for generating a motor current command Im corresponding to the rotation direction command D ₀ and the auxiliary torque of the motor 40, a motor current command Im and a motor. The subtraction means 57 for calculating the current deviation ΔI from the current IM, and the correction amount of the P (proportional) term, the I (integral) term, and the D (differential) term are calculated from the current deviation ΔI and PWM. PID calculating means 58 for generating a current control amount I ₀ corresponding to the duty ratio is provided.

In addition, although not shown, the microcomputer 55 includes other well-known self-diagnosis functions such as an AD converter and a PWM timer circuit, and detects abnormality of the relay 46 at system startup, and also diagnoses a system failure. If no error is found, the relay 46 is turned on and power is supplied to the bridge circuit. Also, whether the system is operating normally even during system operation is always self-diagnosed, and when an abnormality occurs, the relay 46 is opened through the drive circuit 47 to cut off the motor current IM.

Next, the operation of the electric power steering control device will be described with reference to FIG. 4. The microcomputer 55 inputs the steering torque T and the vehicle speed V from the torque sensor 50 and the vehicle speed sensor 51, and feeds back the motor current IM from the shunt resistor 43 to feed the power stage. The rotation direction command D ₀ of the ring and the current control amount I ₀ corresponding to the auxiliary torque amount are generated and output to the drive circuit 47.

In the driving circuit 47 is a normal driving state, and to close the always open relay 46, when the direction of rotation command (D _O) and the current controlled variable (I ₀₎ input, and generates a PWM driving signal, the bridge circuits Each of the semiconductor switching elements Q1 to Q4 at 44 is applied.

As a result, the motor current IM is supplied from the battery 41 to the motor 40 via the relay 46, the shunt resistor 43, and the bridge circuit 44. The motor 40 is driven by this motor current IM, and outputs the required auxiliary torque in the required direction.

At this time, the motor current IM is detected through the shunt resistor 43 and the motor current detecting means 48 and fed back to the subtraction means 57 in the microcomputer 55, thereby matching the motor current command Im. Controlled to. In addition, although the motor current IM contains a ripple component by the switching operation | movement at the time of PWM drive of the bridge circuit 44, it is smoothed and suppressed by the large capacity capacitor | condenser 42. FIG.

By the way, when this type of electric power steering control device is started, after the failure diagnosis, the relay 46 is turned on and the control current according to the desired steering torque T is supplied to the motor to assist the required amount as described above. Operate to output torque. However, since the capacitor 42 uses a large capacity, an excessive inrush current flows to the relay contact when the relay 46 is turned on. As a result, when the start of the control device is repeatedly performed, the contact is welded due to the transition, and the energizing current to the motor 40 cannot be interrupted at the time of system abnormality.

However, in addition to satisfying the desired maximum conduction current, the relay 46 is important for durability of the contact point against the inrush current when the control device is repeatedly started. As a countermeasure, one having a higher conduction current performance is used, which leads to an increase in component cost and thus an increase in product cost.

In addition, in the case of a system having a large auxiliary torque, the control current increases further, and it is necessary to lower the impedance in order to reduce the heat generation of the capacitor 42 due to the increase in the ripple current. There is a problem that becomes larger and higher cost as well as impairs the reliability of the control device.

The present invention has been made to improve the reliability of the control device and to reduce the product cost. Since the relay can be selected based on the maximum control current value by reducing the inrush current, it is preferable to use a relay having a lower cost than before. It is possible to reduce the product cost and improve the reliability.

The present invention, when supplying the operating current to the load through the relay contact from the DC power supply, charges the smoothing capacitor to reduce the ripple component of the operating current in advance, and then closes the relay contact from the DC power supply. By supplying the operating current to the load, the inrush current to the capacitor, that is, the inrush current flowing through the relay contact is reduced.

1 is a block diagram of an electric power steering control apparatus according to an embodiment of the present invention.

2 is a charging circuit of the electric power steering control apparatus according to the present embodiment.

3 is a timing chart showing an operation during system startup of the electric power steering control apparatus according to the present embodiment.

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

1. a relay contact for output control of a drive current from a DC power supply to a large current load, a smoothing capacitor connected between the large current load connection side of the relay contact and earth, and a predetermined time before closing the relay contact with this capacitor. And a preliminary charge control means for closing the relay contact after charging the capacitor in between.

2. The precharge control means is to set the precharge voltage level for the capacitor to an arbitrary value.

3. The preliminary charging control means cuts off the charge after charging the capacitor for a predetermined time.

4. The precharge control means is a circuit configured to not affect the charging voltage of the capacitor which determines the abnormal state such as relay welding.

5. The precharge control means starts the operation of the internal constant voltage circuit at the same time as the control device is started, and immediately starts charging the capacitor.

Example 1

EMBODIMENT OF THE INVENTION Hereinafter, Embodiment 1 of the electric power steering control apparatus of this invention is described with reference to drawings. 1 is a configuration diagram of an electric power steering control device according to the present embodiment. In addition, in the figure, the same code | symbol as FIG. 4 represents the same or an equivalent part. In the drawing, reference numeral 60 denotes a precharging circuit, which precharges the capacitor 42 in advance, and at the same time controls the capacitor by the control signal from the microcomputer 55. Charging to 42 is stopped.

As shown in Fig. 2, the preliminary charging circuit 60 inputs a control signal from the microcomputer 55 to the base and connects a resistor R1 for supplying the base current by the voltage Vcc. A transistor Q1 of one emitter ground and a collector of this transistor Q1 are connected to the base, a bias resistor R2 is connected between the base and the emitter, and a battery voltage V _B is applied to the emitter. A reverse voltage protection diode D1 having an anode connected to the power transistor Q2 and a collector of the power transistor Q2, and connected between a cathode of the reverse breakdown voltage protection diode D1 and a positive terminal of the capacitor 42. The resistor R3, the resistor R3, and the resistor R4 connected between the connection side of the capacitor | condenser 42 and earth are comprised.

The base of the transistor Q1 is connected to the control logic circuit on the microcomputer 55 side, and when charging is unnecessary, the control logic circuit inputs a negative level signal to the base of the transistor Q1 with respect to the voltage Vcc. By blocking the base current to turn off the transistor Q1, the preliminary charging circuit 60 can be turned off. And supplying a voltage (Vcc, V _B) for each transistor (Q1, Q2) and on operation, when sending a charging current to the capacitor 42 is not shown from the battery 41 by turning on the ignition key (SW) Through the constant voltage circuit, the voltages Vcc and V _B are supplied to the transistors Q1 and Q2, respectively. When a voltage (Vcc) is supplied to the transistor (Q1) is turned on, and the voltage (V _B) occurs between the bias resistor (R2). As a result, that on the base current to the power transistor (Q2) flowing, the reverse breakdown voltage protection diode voltage (V _B) between the via (D1) resistance (R3, R4) is generated. This voltage V _B is divided by the ratio of the resistance values of the resistors R3 and R4, and is applied to both ends of the capacitor 42 by the resistor R4 and charged. The power transistor Q2 is protected from the charging voltage of the capacitor 42 by the reverse breakdown voltage protection diode D1. Since the charging voltage level of the capacitor 42 can be set to an arbitrary value by the ratio of R3 and R4, the charging voltage is lowered below the system abnormality detection voltage level and the inrush current prevention effect can be increased as much as possible. The level can be easily set.

Next, the operation of the preliminary charging circuit 60 at the start of the control device will be described with reference to FIG. 3. 3 is a timing chart showing an operation during system startup of the electric power steering control device. In Fig. 3, TO denotes a reset time of the microcomputer 55, T1 denotes a charging time of the condenser 42, T2 denotes a system failure detection time by the microcomputer 55 after completion of charging, V1 denotes a preliminary charge setting voltage, V2 is an abnormality determination voltage such as relay welding, and V3 is a saturation voltage of the capacitor 42 after the relay 46 is turned on.

In the electric power steering control device, for example, it is necessary to shorten the time from when the ignition key 70 is turned on until the system is operated, for example, in the electric power steering control device.

Pre-charge circuit 60 according to the present embodiment is the voltage of the voltage of the battery 41 to the constant-voltage circuit (not shown) simultaneously with the activation of the system in accordance with on of the ignition key 70 is rising (Vcc, V _B) and the micro- It is stabilized at the power supply voltage of the computer and is supplied as the system power to the transistors Q1 and Q2 and the microcomputer 55.

Transistors (Q1, Q2) is a supply voltage (Vcc, V _B) and on operation, also, FIG starts to operate the microcomputer 55. The capacitor 42 is charged by applying a divided voltage of the voltage V _B , which is a ratio of resistance values between the resistors R 3 and R 4. Therefore, the charging of the capacitor 42 is shortened compared to the case where the charging is performed after the reset time TO of the microcomputer 55.

Next, the microcomputer 55 outputs a negative level signal with respect to the voltage Vcc after the charging time T1 constituted by the preliminary charging set voltage V1 set at the resistance value ratio between the resistors R3 and R4. It is applied to the base of Q1 to cut off the base current, and the transistors Q1 and Q2 are turned off to operatively cut off the preliminary charging circuit 60 from the capacitor 42.

Next, the microcomputer 55 diagnoses an abnormality or other failure of the relay 46 during the subsequent failure detection time T2, and if it is normal, operates the drive circuit 47 and turns on the relay 46. Since the capacitor 42 has already been charged up to the preliminary charge set voltage V1, it is generated when the capacitor 46 is charged to the saturation voltage V3 after the relay 41 is turned on and after the relay 41 is turned on by the battery 41. The inrush current from the battery 41 to the condenser 42, that is, the contact current of the relay 46 can be greatly reduced.

In the case where the relay 46 is closed due to contact welding or abnormality of the driving circuit 47, in the former case, the relay 46 is in the same state as on regardless of the system power supply on / off. 42 is always in a charged state until the saturation voltage V3.

In the latter case, however, the battery 41 is charged from the battery 41 to the saturation voltage V3 through the contact point of the relay 46 at the system ON. Regardless, since the battery is charged up to the saturation voltage V3, the fault diagnosis is surely performed.

Moreover, since the rotation of the voltage from the charged capacitor 42 to the internal circuit is interrupted at the time of contact welding of the relay 46 and also at the time of system power-off, there is no system malfunction at the time of abnormality.

As described above, the preliminary charging circuit is cut off after a predetermined time T1 after the system is started by the microcomputer 55 to stop the charging operation to the capacitor 42. Therefore, even when an abnormal occurrence is detected by fault diagnosis during system operation, the relay 46 is immediately turned off and the power supply from the battery 41 to the bridge circuit 44 is cut off, the bridge from the preliminary charging circuit 60 is removed. The circuit 44 is configured so that the driving voltage does not rotate.

As described above, according to the present invention, the capacitor inrush current to the relay contact can be reduced in a relatively simple circuit that does not impair the original operation of the system, and the reliability of the control device can be improved.

When supplying the operating current to the load through the relay contact from the DC power supply, the smoothing capacitor which reduces the ripple component in the operating current is charged in advance, and then the relay contact is closed to supply the operating current to the load from the DC power supply. Therefore, by reducing the inrush current to the capacitor, it is possible to adopt a relay having a smaller current capacity and a lower cost than the conventional relay, thereby realizing a reduction in product cost.

Claims (5)

delete delete A relay contact for output control of a drive current from a direct current power source to a large current load, a smoothing capacitor connected between the high current load connection side of the relay contact and earth, and the capacitor during a predetermined time before closing the relay contact. In the electric power steering control device having a precharge control means for closing the relay contact after charging the charge, The preliminary charging control means may set a preliminary charging voltage level for the capacitor to an arbitrary value, and the charging is interrupted after charging the capacitor for a predetermined time. delete 4. The electric power steering control apparatus according to claim 3, wherein the preliminary charging control means executes the operation of the internal constant voltage circuit at the same time as the control apparatus is started, and immediately starts charging the capacitor.