JP2009067085A - Electric power steering device - Google Patents

Electric power steering device Download PDF

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Publication number
JP2009067085A
JP2009067085A JP2007234351A JP2007234351A JP2009067085A JP 2009067085 A JP2009067085 A JP 2009067085A JP 2007234351 A JP2007234351 A JP 2007234351A JP 2007234351 A JP2007234351 A JP 2007234351A JP 2009067085 A JP2009067085 A JP 2009067085A
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motor
steering
detector
value
current
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JP2007234351A
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JP4946746B2 (en
Inventor
Jun Tsuchimochi
順 土持
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Jtekt Corp
株式会社ジェイテクト
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Abstract

An electric power steering apparatus capable of driving and controlling a steering assist motor at a predetermined share ratio by an auxiliary power source, an in-vehicle generator and an in-vehicle battery connected in series.
A motor 18 for assisting steering, an in-vehicle generator 34 and a battery 26 connected in series as necessary, an auxiliary power source 29 for assisting a current flowing through the motor 18, and a current flowing through the motor 18 are detected. An electric power steering apparatus that includes a first detector 17 that controls the current flowing through the motor 18 based on the detected steering torque value. A second detector 35 that detects a voltage value applied to the drive circuit 13 from the on-vehicle generator 34 and the battery 26, and conversion means 27 that converts the output voltage value of the auxiliary power supply 29 and assists the current that flows to the motor 18. And the third detector 36 for detecting the output voltage value of the conversion means 27, and the output voltage of the conversion means 27 is controlled to rise and fall so that the ratio of the respective voltage values detected by the detectors 35 and 36 becomes a predetermined value. Means 20.
[Selection] Figure 1

Description

  The present invention is connected in series to an in-vehicle generator and an in-vehicle battery, and includes an auxiliary power source for assisting a current flowing through a steering assist motor, and controls the current flowing through the motor based on the steering torque detected by the torque detector. The present invention relates to an electric power steering apparatus.

  The electric power steering device assists the steering force of the vehicle with a motor, and detects a steering torque applied to the steering wheel to a steering mechanism in which a steering member (steering wheel, steering wheel) is connected via a steering shaft. A torque detector and a motor that is supplied with power from an in-vehicle generator and an in-vehicle battery and assists the operation of the steering mechanism are provided. With such a configuration, the operating force to the steered wheels is reduced by driving the motor according to the steering torque detected by the torque detector.

  In an electric power steering device, a large current is required for “at the time of stationary” or the like. However, since the period for which a large current is required is small, a battery or a large-capacitance capacitor is used exclusively for the electric power steering device. There is a configuration in which an auxiliary power supply is provided, and an on-vehicle generator and an on-vehicle battery and an auxiliary power source are connected in series and a current is also supplied from the auxiliary power source at a heavy load such as “when stationary”.

Patent Document 1 discloses an electric power steering apparatus including a main power source and an auxiliary power source as a power supply source for an electric motor used for power assist of a steering gear.
Patent Document 2 discloses a main power system that supplies power to an EPS (electric power steering device) from a high-voltage battery via a step-down system, and a backup power system that supplies power to the EPS via a boost system from an auxiliary battery. Is a power supply system configured in parallel, and when the main power system cannot normally supply power to the EPS, a power supply control device that controls the boosting system and supplies power from the backup power system to the EPS is disclosed. ing.
JP 2003-320942 A JP 2006-213273 A

  As described above, in the electric power steering device in which the in-vehicle generator and the in-vehicle battery and the auxiliary power source are connected in series at the time of a heavy load, the flowing current value is the same as the auxiliary power source and the in-vehicle generator and the in-vehicle battery as the main power source. It is. Therefore, since the load sharing ratio between the auxiliary power source and the main power source is proportional to the output voltage, there is a problem that the auxiliary power source cannot be used effectively when the output voltage of the auxiliary power source is low.

The present invention has been made in view of the circumstances as described above. In the first and second inventions, the auxiliary power source, the in-vehicle generator and the in-vehicle battery connected in series are used for steering assist at a predetermined sharing ratio. An object of the present invention is to provide an electric power steering apparatus capable of driving and controlling the motor.
In the third aspect of the present invention, when the auxiliary power source, the on-vehicle generator and the on-vehicle battery connected in series drive and control the steering assist motor at a predetermined sharing ratio and no current is supplied to the steering assist motor. An object of the present invention is to provide an electric power steering device capable of charging an auxiliary power source.

  An electric power steering apparatus according to a first aspect of the present invention includes a steering assist motor driven by a drive circuit to which an output voltage from an in-vehicle generator and an in-vehicle battery is applied, and the in-vehicle generator and the in-vehicle battery as necessary. An auxiliary power source connected in series for assisting the current flowing through the motor, a torque detector for detecting a steering torque value applied to the steering member, and a first detector for detecting a current value flowing through the motor; In the electric power steering apparatus configured to control a current value flowing through the motor based on a steering torque value detected by the torque detector, a voltage applied to the drive circuit from the in-vehicle generator and the in-vehicle battery A second detector for detecting the value; a conversion means for converting the output voltage value of the auxiliary power supply to assist the current flowing through the motor; and the conversion means A third detector for detecting an output voltage value, and a means for raising and lowering the output voltage of the conversion means so that the ratio of the respective voltage values detected by the second detector and the third detector becomes a predetermined value. It is characterized by providing.

  The electric power steering apparatus according to the second invention further comprises means for determining whether or not the current value detected by the first detector is equal to or greater than a predetermined current value, and determines that the means is equal to or greater than the predetermined current value. In this case, the conversion means is configured to be connected in series to the in-vehicle generator and the in-vehicle battery and operate.

  An electric power steering apparatus according to a third aspect of the present invention is the parallel determination of the determination means for determining whether or not the current value detected by the first detector is 0, the auxiliary power source, the in-vehicle generator and the in-vehicle battery. A connecting means for connecting, and when the determining means is determined to be 0, the connecting means is connected, and when the determining means is determined not to be 0, the connecting means is connected. It is characterized by not being configured.

  According to the electric power steering apparatus of the first invention, the second detector detects the voltage value applied to the drive circuit from the on-vehicle generator and the on-vehicle battery, and the conversion means converts the output voltage value of the auxiliary power supply. Then, the current flowing through the motor is assisted, the third detector detects the output voltage value of the conversion means, and the ratio between the voltage values detected by the second detector and the third detector becomes a predetermined value. Thus, the means for raising and lowering control raises and lowers the output voltage of the conversion means, so that the steering assist motor is driven and controlled at a predetermined sharing ratio by the auxiliary power source connected in series, the in-vehicle generator and the in-vehicle battery. An electric power steering device that can be realized can be realized.

  According to the electric power steering apparatus according to the second aspect of the invention, it is determined whether or not the current value detected by the first detector is equal to or greater than a predetermined current value, Since the conversion means operates in series with the in-vehicle generator and the in-vehicle battery, when a large current is required, the auxiliary power source connected in series and the in-vehicle generator and the in-vehicle battery steer at a predetermined sharing ratio. An electric power steering device that can drive and control an auxiliary motor can be realized.

  According to the electric power steering apparatus of the third aspect of the invention, it is determined whether or not the current value detected by the first detector is 0. When it is determined that the current value is 0, the auxiliary power source and the on-vehicle generator And in-vehicle battery connected in parallel, and when it is determined that it is not 0, it is not connected in parallel, so the auxiliary power source connected in series with the in-vehicle generator and the in-vehicle battery at a predetermined sharing ratio It is possible to realize an electric power steering apparatus capable of charging the auxiliary power source when the motor for driving is controlled and current is not supplied to the steering assist motor.

Hereinafter, the present invention will be described with reference to the drawings showing embodiments thereof.
FIG. 1 is a block diagram showing a main configuration of an embodiment of an electric power steering apparatus according to the present invention.
In this electric power steering device, a steering torque applied to a steering member 23 (steering wheel, steering wheel) is detected by a torque sensor (torque detector) 10. The detected steering torque value has a positive / negative sign indicating the steering direction, and is supplied to the phase compensator 12. The steering torque value phase-compensated by the phase compensator 12 is given to a torque-current table 16 of an ECU (Electric Control Unit) 25. The vehicle speed value detected by the vehicle speed sensor 11 is also given to the torque-current table 16.

  In the torque-current table 16, when the steering torque value exceeds a predetermined dead zone, the target value of the motor current increases proportionally as the steering torque value increases, and when the steering torque value becomes equal to or greater than the predetermined value, the target value is saturated. Such a function is variably determined according to the vehicle speed value. The function is determined so that the ratio of the target value of the motor current to the steering torque value decreases as the vehicle speed value increases, and the saturation value of the target value decreases.

The target value of the motor current determined by the torque-current table 16 is a value indicating the target value in the motor control and is given to the subtracting means 21.
The command current direction designating unit 19 creates a rotation direction command signal indicating the steering assist direction based on the sign of the steering torque value given from the torque-current table 16 and gives it to the motor drive circuit (drive circuit) 13. .

The motor drive circuit 13 is supplied with the output voltage of the in-vehicle battery 26 and the output voltage of an alternator (on-vehicle generator, AC generator) 34 that is linked to an engine (not shown) through the relay contact 15a and the changeover switch 28. The output voltage of the alternator 34 is held at a constant voltage by an added regulator and is rectified to a direct current.
Further, when the changeover switch 28 is switched, the output voltage of the DC-DC converter (conversion means) 27 connected in series to the in-vehicle battery 26 and the alternator 34 is further applied to the motor drive circuit 13. The DC-DC converter 27 converts the output voltage value of the auxiliary power supply 29 dedicated to the electric power steering apparatus and outputs the converted voltage. The changeover switch 28 is controlled by the control unit 20 to switch whether the DC-DC converter 27 is connected in series to the in-vehicle battery 26 and the alternator 34.

As the auxiliary power source 29, a lead storage battery, a lithium ion battery, a large capacity capacitor (electric double layer capacitor) or the like is used (a storage battery is shown in FIGS. 1 and 2), a relay contact 15a, a changeover switch 28, and a relay contact (connection). Means) The battery is charged from the in-vehicle battery 26 and the alternator 34 through 31. At that time, the negative terminal of the auxiliary power supply 29 is grounded by the relay contact (connecting means) 32. The relay contacts 31 and 32 are turned on / off by the relay drive circuit 30.
A voltage detector (second detector) 35 detects the output voltage values of the in-vehicle battery 26 and the alternator 34, and a voltage detector (third detector) 36 detects the output voltage value of the DC-DC converter 27. To the control unit 20 respectively.

The motor 18 for assisting steering is a brushless DC motor in the present embodiment, and includes a rotor position detector 14 for detecting the rotor position. The rotor position signal output from the rotor position detector 14 is a motor drive circuit. 13 is given.
A motor current detection circuit (first detector) 17 detects a current value flowing through the motor 18 and supplies it to the subtracting means 21 and the control unit 20 in the ECU 25.
The subtracting means 21 calculates a deviation between the target value of the motor current determined by the torque-current table 16 and the current value detected by the motor current detection circuit 17, and gives the calculated deviation to the current PI control unit 22.

The current PI control unit 22 calculates a voltage value to be applied to the motor 18 for PI control based on the given deviation, and supplies the voltage value to a PWM (Pulse Width Modulation) modulation unit 24.
The PWM modulation unit 24 performs pulse width modulation on the applied voltage value, and supplies the pulse voltage modulated voltage value to the motor drive circuit 13 as a PWM value command signal.
Based on the current value detected by the motor current detection circuit 17 and the voltage values detected by the voltage detectors 35 and 36, the control unit 20 controls the changeover switch 28 and controls the relay drive circuit 30 on / off. At the same time, the output voltage of the DC-DC converter 27 is controlled to rise and fall.

Further, the control unit 20 is given an on / off signal of an ignition switch (IG switch) 33, and controls the relay drive circuit 15 on / off in response to the IG switch 33 being turned on / off, The relay contact 15a is turned on / off (closed / open).
The phase compensator 12, the torque-current table 16, the subtracting means 21, the command current direction specifying unit 19, the control unit 20, the current PI control unit 22, and the PWM modulation unit 24 in the ECU 25 described above are realized by a microcomputer. ing.

  FIG. 2 is a block diagram showing a configuration example of the motor 18, the motor drive circuit 13, the motor current detection circuit 17, and the power supply system of the electric power steering apparatus shown in FIG. The motor 18 that is a brushless motor includes a stator 18a in which one terminal of each of the coils A, B, and C is star-connected, and a rotor (rotor) 18b that is rotated by a rotating magnetic field generated by the coils A, B, and C. And a rotor position detector (rotary encoder) 14 for detecting the rotational position of the rotor 18b.

  The motor drive circuit 13 includes transistors Q1 and Q2 connected in series between a positive terminal and a ground terminal and diodes D1 and D2 connected in series in the opposite direction in parallel, and transistors Q3 and Q3 connected in series. Q4 and diodes D3 and D4 connected in series in the reverse direction are connected in parallel, and transistors Q5 and Q6 connected in series and diodes D5 and D6 connected in series in the reverse direction are connected in parallel.

  The other terminal U of the star-connected coil A is connected to the common connection node of the transistors Q1 and Q2 and the common connection node of the diodes D1 and D2, and the common connection node of the transistors Q3 and Q4 and the diode D3 The other terminal V of the coil B that is star-connected is connected to the common connection node of D4, and star-connected to the common connection node of the transistors Q5 and Q6 and the common connection node of the diodes D5 and D6. The other terminal W of the coil C is connected.

  The rotational position of the rotor 18b detected by the rotor position detector 14 is notified to the gate control circuit 13a. A rotation direction command and a motor current command value (PWM command value) are given from the ECU 25 to the gate control circuit 13a. The gate control circuit 13a turns on / off the gates of the transistors Q1 to Q6 according to the rotation direction command and the rotation position of the rotor 18b, for example, U-V, U-W, V-W, V- As in U, W-U, W-V, and U-V, the path of the current flowing through the stator 18a is switched to generate a rotating magnetic field. The rotor 18b is a permanent magnet and rotates by receiving a rotational force from the rotating magnetic field.

In addition, the gate control circuit 13a performs increase / decrease control of the rotational torque of the brushless motor 18 by performing PWM control of on / off of the transistors Q1 to Q6 according to the motor current command value (PWM command value).
The diodes D1 to D6 are for absorbing noise generated by turning on / off the transistors Q1 to Q6.
As described above, the motor current detection circuit 17 detects the current flowing through the brushless motor 18 and supplies it to the ECU 25 as a motor current signal.

Output voltages of the in-vehicle battery 26 and the alternator 34 are supplied to the positive terminal of the motor drive circuit 13 through the changeover switch 28. When the DC-DC converter 27 is connected in series to the in-vehicle battery 26 and the alternator 34 by the changeover switch 28, the output voltage of the DC-DC converter 27 is further applied. The output voltage of the DC-DC converter 27 is a voltage obtained by converting the output voltage of the auxiliary power supply 29.
The output voltage value of the DC-DC converter 27 detected by the voltage detector 36 and the output voltage values of the in-vehicle battery 26 and the alternator 34 detected by the voltage detector 35 are given to the control unit 20.

The relay contacts 31 and 32 are ON / OFF controlled by the control unit 20 (FIG. 1) through the relay drive circuit 30 (FIG. 1) based on the current value detected by the motor current detection circuit 17.
The output voltage of the DC-DC converter 27 is controlled to be raised and lowered by the control unit 20 (FIG. 1) based on the voltage values detected by the voltage detectors 35 and 36.

Hereinafter, an example of the operation of the electric power steering apparatus having such a configuration will be described with reference to the flowcharts of FIGS.
When the IG switch 33 is turned on (S1), the controller 20 turns off the relay drive circuit 30, turns off the relay contacts (charging relay contacts) 31, 32 (S3), and switches the changeover switch. 28 is switched to the side (direct side) where the in-vehicle battery 26 and the alternator 34 are directly connected to the motor drive circuit 13 (S5). Next, the relay drive circuit 15 is turned on, and the relay contact (power supply relay contact) 15a is turned on (closed) (S7).
Next, the control unit 20 reads the current value I flowing through the motor 18 detected by the motor current detection circuit 17 (S9), and determines whether or not the current value I exceeds 0 (S11).

If the current value I does not exceed 0 (S11), the controller 20 turns on the relay drive circuit 30 and turns on (closes) the relay contacts (charging relay contacts) 31, 32 (S27). Then, the current value I flowing in the motor 18 detected by the motor current detection circuit 17 is read (S9).
If the current value I exceeds 0 (S11), the controller 20 turns off the relay drive circuit 30 and turns off (opens) the relay contacts (charging relay contacts) 31, 32 (S13). Then, it is determined whether or not the current value I (S9) is equal to or greater than a predetermined current value indicating that the load of the motor 18 is large (S15).

  If the current value I (S9) is not equal to or greater than the predetermined current value (S15), the controller 20 switches the changeover switch 28 to the direct side (S29) and turns off the DC-DC converter 27 (S31), and then the motor The current value I flowing through the motor 18 detected by the current detection circuit 17 is read (S9). If the current value I (S9) is equal to or greater than the predetermined current value (S15), the DC-DC converter 27 is turned on (S17), and the changeover switch 28 is switched to the DC-DC converter 27 side (auxiliary power supply 29 side) (S19). ). Next, the (output) voltage value Vm of the main power source (vehicle battery 26, alternator 34) detected by the voltage detector 35, and the (output) voltage of the DC-DC converter 27 (auxiliary power source side) detected by the voltage detector 36. The value Vs is read (S21).

  Next, the control unit 20 determines whether or not the ratio Vs / Vm of the read voltage value Vs and voltage value Vm (S21) exceeds a predetermined ratio (S23), and if the ratio exceeds the predetermined ratio, After giving a step-down command to the DC-DC converter 27 (S33), the current value I flowing through the motor 18 detected by the motor current detection circuit 17 is read (S9). When the step-down command is given, the DC-DC converter 27 drops the output voltage by a predetermined unit voltage.

If the ratio Vs / Vm does not exceed the predetermined ratio (S23), the control unit 20 determines whether the ratio Vs / Vm is less than the predetermined ratio (S25). After giving a boost command to the DC converter 27 (S35), the current value I flowing through the motor 18 detected by the motor current detection circuit 17 is read (S9). When the boost command is given, the DC-DC converter 27 increases the output voltage by a predetermined unit voltage.
If the ratio Vs / Vm is not less than the predetermined ratio (S25) (that is, Vs / Vm = predetermined ratio), the control unit 20 reads the current value I flowing through the motor 18 detected by the motor current detection circuit 17 as it is. (S9).

It is a block diagram which shows the principal part structure of embodiment of the electric power steering apparatus which concerns on this invention. It is a block diagram which shows the structural example of the motor shown in FIG. 1, a motor drive circuit, a motor current detection circuit, and a power supply system. It is a flowchart which shows the example of operation | movement of the electric power steering apparatus which concerns on this invention. It is a flowchart which shows the example of operation | movement of the electric power steering apparatus which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Torque sensor (torque detector), 13 Motor drive circuit (drive circuit), 15 Relay drive circuit, 15a Relay contact, 16 Torque-current table, 17 Motor current detection circuit (1st detector), 18 (For steering assistance) Motor), 20 control unit (means for raising and lowering control), 23 steering member, 25 ECU, 26 on-vehicle battery, 27 DC-DC converter (conversion means), 28 changeover switch, 29 auxiliary power supply, 30 relay drive circuit (connection means) ), 31, 32 Relay contact (connecting means), 35 Voltage detector (second detector), 36 Voltage detector (third detector), 34 Alternator (vehicle generator, AC generator).

Claims (3)

  1. A steering assist motor driven by a drive circuit to which an output voltage from the in-vehicle generator and the in-vehicle battery is applied, and, if necessary, connected in series to the in-vehicle generator and the in-vehicle battery, assisting the current flowing through the motor An auxiliary power source for detecting the steering torque value applied to the steering member, and a first detector for detecting a current value flowing through the motor, the steering torque value detected by the torque detector being Based on the electric power steering device configured to control the current value flowing through the motor,
    A second detector for detecting a voltage value applied to the drive circuit from the in-vehicle generator and the in-vehicle battery, conversion means for converting an output voltage value of the auxiliary power source and assisting a current flowing through the motor; The output voltage of the conversion means is adjusted so that the ratio of the respective voltage values detected by the third detector for detecting the output voltage value of the conversion means and the second detector and the third detector becomes a predetermined value. An electric power steering apparatus comprising: means for controlling the elevation.
  2.   Means for determining whether the current value detected by the first detector is greater than or equal to a predetermined current value, and when the means determines that the current value is greater than or equal to a predetermined current value, The electric power steering apparatus according to claim 1, wherein the electric power steering apparatus is configured to be connected in series to the in-vehicle generator and the in-vehicle battery.
  3.   A determination unit that determines whether or not the current value detected by the first detector is 0; and a connection unit that connects the auxiliary power source, the in-vehicle generator, and the in-vehicle battery in parallel. The connection means is connected when the means is determined to be 0, and the connection means is not connected when the determination means is determined not to be 0. 3. The electric power steering apparatus according to 2.
JP2007234351A 2007-09-10 2007-09-10 Electric power steering device Expired - Fee Related JP4946746B2 (en)

Priority Applications (1)

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JP2007234351A JP4946746B2 (en) 2007-09-10 2007-09-10 Electric power steering device

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Application Number Priority Date Filing Date Title
JP2007234351A JP4946746B2 (en) 2007-09-10 2007-09-10 Electric power steering device

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JP2009067085A true JP2009067085A (en) 2009-04-02
JP4946746B2 JP4946746B2 (en) 2012-06-06

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003320942A (en) * 2002-04-26 2003-11-11 Nsk Ltd Electric power steering apparatus
JP2007153079A (en) * 2005-12-02 2007-06-21 Toyota Motor Corp Power supply device of electric power steering apparatus
JP2007223510A (en) * 2006-02-24 2007-09-06 Jtekt Corp Electric power steering device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003320942A (en) * 2002-04-26 2003-11-11 Nsk Ltd Electric power steering apparatus
JP2007153079A (en) * 2005-12-02 2007-06-21 Toyota Motor Corp Power supply device of electric power steering apparatus
JP2007223510A (en) * 2006-02-24 2007-09-06 Jtekt Corp Electric power steering device

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