JP4456517B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus having a booster circuit in a power source.

  The electric power steering device detects a steering torque generated in the steering shaft when steering the steering handle, and generates a steering assist force by driving a motor when a large steering force is required based on this detection signal. , It operates to reduce the steering force of the steering handle. That is, when the steering handle is being steered, if the steering torque is large, a large steering force is required, so the target value of the motor current is set so as to supply a large steering assist force, Feedback control is performed so that the actual current value of the motor matches the target value. Further, when the steering torque is small, a large steering force is not required, so the target value of the motor current is set so as to supply a small steering assist force.

  By the way, in such a system, current does not always flow through the motor, and current does not flow through the motor unless the steering handle is driven. However, when the motor requires a current, a large current needs to flow. When the maximum steering assist force is required, the required power is about 600 watts to 800 watts for a normal 2000 cc class car. The above current may be required.

  In order to control such a large current, a semiconductor switching element corresponding to the large current is required. The size of the semiconductor switching element is determined by the amount of current that can be passed. Moreover, in order to actually perform chopper control of a large current, a semiconductor switching element having a peak current value of 1.5 to 2 times the maximum current flowing through the motor is required, which increases the size and cost of the circuit. Inevitable. In order to pass a larger current, the wiring around the circuit is also required to be thick enough to pass the current, and the weight of the wiring becomes a problem. Furthermore, if the motor current is limited, a larger motor is required to obtain a predetermined torque, resulting in a problem that the apparatus becomes larger. In addition, there is a known phenomenon that when the motor rotates fast, the electromotive force from the motor increases and current does not flow easily. In addition, if a large current is taken from the battery (battery), the voltage of the battery will drop each time the steering wheel is steered, noise will be generated in the electrical system, and the brightness of the headlamp will fluctuate during night driving. It was a cause to wake up.

  In order to solve such a problem, an example of a power supply device in which a second battery is provided on the output side of the booster circuit has been reported. For example, a first battery, a booster connected to the first battery, a second battery connected to the booster, and a torque signal of the steering handle connected to the second battery There has been reported an example of a power supply device for electric power steering configured by a control circuit for supplying driving power of a steering motor corresponding to the above and a steering motor connected to the control circuit (see Patent Document 1).

As shown in FIG. 8, the power supply device 25 of Patent Document 1 boosts the voltage of the first battery 31 by the booster 32, stores electric power in the second battery 33, and steers the motor 19 from the second battery 33. Since electric power is supplied to a load such as the booster 32, the booster 32 can be reduced in size, and the circuit weight and cost can be reduced. Moreover, since the voltage fluctuation of the 1st battery 31 does not arise even if an apparatus is used, the fluctuation | variation of the brightness of the lamp for illumination connected to the 1st battery 31 can be reduced.
Japanese Patent Publication No. 8-539

However, when connecting the second battery to the output of the booster in this way,
1) The voltage becomes a voltage that is an integral multiple of a unit battery that is generally used, and the voltage has a low degree of freedom and cannot take an arbitrary voltage value.
2) Since the boosted voltage is determined by the voltage of the second battery, it cannot be changed according to the situation.
3) Since a normal storage battery (battery) has a lifetime and is a regular replacement product, it is a system that requires complicated maintenance and high maintenance costs.
4) The apparatus becomes large when a plurality of batteries are used to obtain a predetermined voltage. In addition, the use of a special battery increases the cost.
5) Since the load is driven by the battery attached to the output of the booster, the voltage cannot be increased even if the battery voltage is lowered. Therefore, when the steering handle is operated quickly, the current does not easily flow to the load.
6) Since an ordinary lead battery cannot accurately estimate the charge that can be taken out, it is difficult to control the output according to the battery condition.
Problems such as are born.

  The present invention solves these problems, and it is an object of the present invention to realize an electric power steering apparatus that has high degree of freedom in voltage, is easy to maintain, has a long service life of components, has a small burden on the battery, and can perform steering assistance. And

  In order to solve the above problems, an electric power steering apparatus according to the present invention is an electric power steering apparatus that calculates a target current based on at least an output signal from a steering input detection unit and controls a motor based on the target current. The apparatus includes a booster that boosts an output voltage of a power supply and supplies the boosted voltage to the motor, and a capacitor that is provided on the input side of the booster and discharges electric power. According to this, even if the voltage of the battery decreases, boosting is performed using the capacity means provided on the input side of the boosting means.

  The electric power steering apparatus includes a discharge power control unit that controls discharge from the capacity unit to the boost unit. In this way, motor information can be obtained and correction can be made in consideration of the output control of the capacity means.

  The electric power steering apparatus may include supply power control means for controlling power supply to the boosting means of the battery. Thereby, the electric current from a battery to a pressure | voltage rise means can be restrict | limited.

  The electric power steering apparatus further includes power control means for controlling charging of the capacity means from the output of the boosting means. In this way, the capacity means can be charged when the load on the battery is small such that the output voltage of the battery is higher than the reference voltage.

  In the electric power steering power supply control device having a power control means for controlling charging of the capacity means from the output of the boosting means, the power control means is configured such that when the voltage of the battery decreases or from the boosting means When the output voltage decreases, the charging power can be increased.

  In the electric power steering apparatus configured to increase charging power when the voltage of the battery decreases or when the voltage output from the boosting unit decreases, the capacity unit includes power connecting the battery and the boosting unit. The other line is arranged on a line different from the supply line, and one end of the other line is connected to the capacity means from the output side of the boosting means, and the output voltage or current of the battery is lower than a reference value at the other end. It is preferable to be connected to the input side of the boosting means through a switching means that conducts when the voltage is low.

  In the electric power steering apparatus having a configuration in which the capacity means is arranged on a line different from the power supply line connecting the battery and the boosting means, the capacity means includes a plurality of capacity means, It is preferable to have switching means for switching the connection with the other line in parallel or in series. In this way, when the capacity means is connected in parallel, charging is performed, and the battery voltage drops, the capacitor voltage is doubled by switching to the serial connection, so that the battery voltage drop can be compensated. I can do it.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power steering apparatus which has a high degree of freedom of a voltage, is easy to maintain, has a long component life, has little burden on a battery, and can perform steering assistance is realizable.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the configuration of an electric power steering apparatus 10 according to an embodiment of the present invention. This device is composed of a drive mechanism 9 and a power supply control device 1, and when a steering handle 11 is rotated, a steering shaft 12 directly connected to the steering handle 11 is connected via a connected torque sensor 20 (steering input detecting means). Then, the pinion 13 constituting the rack and pinion mechanism 15 is rotated, whereby the rack shaft 14 is moved to change the direction of the front wheel 17 and steer. At this time, in accordance with the torque signal T detected by the torque sensor 20 and the vehicle speed signal V detected by the vehicle speed sensor 21, the control circuit 22 supplies power from the power supply control device 1 to the motor 19 and controls the target motor current to flow. . With this supplied power, the motor 19 rotates the pinion 13 via the power transmission mechanism 18 and operates to reduce the steering torque of the steering handle 11.
That is, the power supply control device 1 has a function of supplying electric power that flows to the motor 19 that provides the steering assist force. In order to realize this function, the power supply control device 1 has a capacitor that holds the charge. When the voltage of the battery (primary power supply) that supplies power to the input side of the booster circuit drops, the charge of this capacitor is given to the input side of the booster circuit to compensate for the battery power shortage It is configured.

FIG. 2 is a circuit block diagram of the power supply control device 1a constituting the electric power steering device 10a according to the embodiment of the present invention. In FIG. 2, reference numeral 2 is a battery, reference numeral 3 is a booster circuit (boost means), reference numeral 10a is an electric power steering device, reference numeral C is a capacitor (capacitance means), reference numeral D1 is a diode (diode means), reference numeral D2 is another Diode, symbol Q is a voltage comparison circuit, symbol R is a resistor, symbol S is a semiconductor switching element (switch means), and symbol Vr is a reference voltage. The semiconductor switching element S may be anything as long as it can switch high power, such as a MOSFET or a bipolar transistor.
The battery 2 is connected to the input of the booster circuit 3 via the diode D2, and the control circuit 22 is connected to the output. A semiconductor switching element S, a resistor R, and a diode D1 are connected in series between the input and output of the booster circuit 3. Here, the diode connected in parallel between the drain and source of the semiconductor switching element S is a protective diode. The substrate is preferably connected to the drain, source or ground terminal. Further, a capacitor C is connected to a connection point between one end of the semiconductor switching element S and the resistor R, and the output voltage of the booster circuit 3 is charged via the diode D1. The output of the voltage comparison circuit Q is connected to the gate of the semiconductor switching element S, the reference voltage Vr is applied to the normal input (+), and the voltage of the battery 2 is applied to the inverted input (−). Yes.

The operation of the present embodiment will be described with reference to FIG.
When the output voltage of the booster circuit 3 is higher than the voltage of the capacitor C, the capacitor C is always charged via the diode D1 and the resistor R. When the apparatus is started up, a precharge circuit may be separately provided for charging. For example, the capacitor C having 50 F and an operating voltage of 25 V is used. The diode D1 has a function of preventing the backflow of the charge of the capacitor C to the output side of the booster circuit 3, and the resistor R limits the charging current to the capacitor C and prevents a large current from flowing transiently. It has a function.

  The output voltage of the battery 2 is compared with the reference voltage Vr by the voltage comparison circuit Q. If the battery voltage of the battery 2 is 12V, the reference voltage Vr is set to 11V, for example. When the load of the system connected to the battery 2 increases, the power from the battery 2 is often taken out, and the output voltage of the battery 2 becomes lower than the reference voltage Vr (11 V), the voltage comparison circuit Q works to make the semiconductor switching element S As a result, the power of the capacitor C is supplied to the input side of the booster circuit 3. At this time, since the diode D2 connected between the battery 2 and the input of the booster circuit 3 has a reverse voltage, the connection between the battery 2 and the input of the booster circuit 3 is disconnected.

  When the power of the capacitor C is supplied to the input side of the booster circuit 3 and thereby the load on the battery 2 is lightened and the output voltage rises and becomes higher than the reference voltage Vr (11 V), the voltage comparison circuit Q becomes a semiconductor. The switching element S1 is turned off. Then, the connection between the capacitor C and the input side of the booster circuit 3 is established, and a current flows from the battery 2 to the input of the booster circuit 3 via the diode D2.

Thus, in the present embodiment, it is possible to control power supply from the battery 2 as the primary power supply and the capacitor C as the auxiliary power supply to the booster circuit 3 without providing a special control circuit. When the load is large and the output voltage of the battery 2 decreases, power is supplied from the capacitor C to reduce the load on the battery 2 and to sufficiently supply power to the control circuit 22 that is the load of the power supply control device 1a. Make it possible.
Although it has been described that the capacitor C is always charged by the output of the booster circuit 3, a semiconductor switching element is provided between the capacitor C and the output of the booster circuit 3 and is controlled by the inverted output of the voltage comparison circuit Q. The capacitor C may be charged only when the output voltage of the battery 2 is higher than the reference voltage Vr and the burden on the battery 2 is small. Alternatively, charging can be performed by always operating a precharge circuit provided separately.

  FIG. 3 shows a circuit block diagram of a power supply control device 1b constituting an electric power steering device 10b according to another embodiment of the present invention. In FIG. 3, reference numeral 4 is a capacitor output control device (discharge power control means), reference numeral 7 is control information, reference numeral Re is a relay, and other elements having the same functions are the same as those in FIG. It attached | subjected and showed.

  This embodiment differs from that shown in FIG. 2 in that the capacitor output control device 4 obtains the control information 7 of the control circuit 22 that is a load, and makes corrections in consideration of the output control of the capacitor C. It is a point to be. Another difference is that a relay Re is inserted between the semiconductor switching element S and the booster circuit 3.

  Also in this embodiment, when the output voltage of the booster circuit 3 is higher than the voltage of the capacitor C, the capacitor C is always charged via the diode D1 and the resistor R by the output of the booster circuit 3. Alternatively, a switching element is also provided between the capacitor C and the booster circuit 3 output, and the capacitor is controlled only when the load of the battery 2 is small under the control of the capacitor output control device 4 such that the output voltage of the battery 2 is higher than the reference voltage. C may be charged.

  The capacitor output control device 4 monitors the voltage of the capacitor C and keeps the relay Re turned on when the charge becomes a predetermined value or more, and the output voltage of the battery 2 is set to a reference voltage (for example, a battery voltage of 12V). 11V), the semiconductor switching element S is turned on, and the power of the capacitor C is supplied to the input of the booster circuit 3. Therefore, in this state, when the voltage of the capacitor C is sufficiently high and the output voltage of the battery 2 becomes lower than the reference voltage, the power of the capacitor C is automatically supplied to the input of the booster circuit 3. Further, since the current from the capacitor C can be prevented from flowing into the battery 2 by controlling the switching element S, the diode 2 can be omitted.

Further, the capacitor output control device 4 monitors the voltage of the capacitor C and corrects the reference voltage which is the threshold value of the battery 2 according to the magnitude of the voltage, and discharges the power of the capacitor C to the input of the booster circuit 3. It can also be adjusted. That is, when the charge amount of the capacitor C is small and the voltage is low, the reference voltage is lowered so that the power discharge from the capacitor C to the input of the booster circuit 3 does not occur even if the voltage of the battery 2 drops to some extent. Try to increase the current burden. Thereby, the assist time by the capacitor C and the voltage of the battery 2 can be adjusted.

  FIG. 4 shows a circuit block diagram of a power supply control device 1c constituting an electric power steering device 10c according to still another embodiment of the present invention. 4, reference numeral 5 is an input current control discharge control circuit (supply power control means, discharge power control means), reference numerals S1 and S2 are semiconductor switching elements, reference numerals R1 and R2 are resistors, Elements having the same functions as those in FIG. 3 are denoted by the same reference numerals as those in FIGS.

  This embodiment differs from the embodiment of FIGS. 2 and 3 in that a semiconductor switching element S2 is inserted between the battery 2 and the diode D2. In addition, an input current control discharge control circuit 5 is provided, and the semiconductor switching element S2 is used to limit the current from the battery 2 to the booster circuit 3 input side, and the semiconductor switching element S1 is used to input the booster circuit 3 to the capacitor C. The difference is that the discharge control is performed simultaneously.

  The capacitor C is a precharge circuit composed of a resistor R2 before the device is activated, and is charged to, for example, about 12V by the voltage of the battery 2. Further, after the device is started, when the output voltage of the booster circuit 3 is higher than the voltage of the capacitor C, the output of the booster circuit 3 is always charged via the diode D1 and the resistor R1. Alternatively, a semiconductor switching element is also provided between the capacitor C and the output of the booster circuit 3, and the load on the battery 2 in which the output voltage of the battery 2 is higher than the reference voltage under the control of the input current control discharge control circuit 5 is small. The capacitor C may be charged only in such a case.

  The input current control discharge control circuit 5 connects the output from the capacitor C to the input side of the booster circuit 3 when the load on the control circuit 22 increases and the discharge current from the battery 2 increases. Further, the voltage of the capacitor C or the voltage of the battery is detected, and the semiconductor switching element S1 and the semiconductor switching element S2 are intermittently connected according to the detected value, and the current input from the battery 2 to the booster circuit 3 and the capacitor C To control the current input to the booster circuit 3 so that the voltage of the battery 2 does not fall below 11 V as much as possible, and the discharge time from the capacitor C can be made as long as possible by increasing the charge of the capacitor C. Adjust to.

  FIG. 5 shows a circuit block diagram of a power supply control device 1d constituting an electric power steering device 10d according to another embodiment of the present invention. In FIG. 5, reference numeral 6 denotes a charging current control circuit, and reference numeral S3 denotes a semiconductor switching element. The charging current control circuit 6 and the semiconductor switching element S3 constitute a power control means 8. The other elements having the same functions as those shown in FIGS. 2, 3 and 4 are denoted by the same reference numerals as those shown in FIGS.

  This embodiment differs from that shown in FIG. 4 in that a semiconductor switching element S3 is provided instead of the resistor R1, and charging of the capacitor C is controlled by the charging current control circuit 6. In particular, the semiconductor switching element S3 is connected between the diode D1 and the capacitor C and the semiconductor switching element S1, and the gate potential is controlled by the charging current control circuit 6.

  When the output voltage of the battery 2 is higher than the reference voltage (11V), the input current control discharge control circuit 5 sends a message to that effect to the charge current control circuit 6, and the charge current control circuit 6 further supplies the load current of the booster circuit 3. As a result, when the output voltage of the battery 2 is higher than the reference voltage (11V) and the load current of the booster circuit 3 is smaller than 20A, the semiconductor switching element S3 is turned on to charge the capacitor C.

  When the load current supplied from the booster circuit 3 to the control circuit 22 increases and exceeds 20 A, the charging current control circuit 6 controls the semiconductor switching element S3 to gradually decrease the charging of the capacitor C, thereby boosting the voltage. When the load current of the circuit 3 exceeds 40 A, the charging is controlled to stop. In addition, the charging current control circuit 6 normally performs a constant charge, but when the output voltage of the booster circuit 3 decreases due to a large amount of power being taken out or when the battery voltage decreases, the charge amount is increased more than usual, It functions as a power control means together with the semiconductor switching element S3.

  When the load current from the booster circuit 3 temporarily increases and thereby the output voltage of the battery 2 becomes lower than the reference voltage (11V), the input current control discharge control circuit 5 turns on the semiconductor switching element S1. The output of the capacitor C is connected to the input of the booster circuit 3 to assist power. In this case, the charging current control circuit 6 prohibits charging of the capacitor C by turning off the semiconductor switching element S3 even when the load current of the booster circuit 3 is smaller than 20A.

  As described above, the present embodiment has a function of controlling the charging and discharging of the capacitor C, and charges the capacitor C when the output of the battery 2 has a margin and the output current of the booster circuit 3 is small. When the voltage of the battery 2 decreases, power is supplied to the input of the booster circuit 3 by the output of the capacitor C, and charging is not performed while the capacitor C is discharged. Therefore, when the battery 2 and the booster circuit 3 have a margin, the capacitor C is charged. When the output of the battery 2 starts to be insufficient, the output of the capacitor C is compensated to reduce the burden on each part. Can be done.

6 and 7 are circuit block diagrams of a power supply control device 1e constituting an electric power steering device 10e according to another embodiment of the present invention. 6 and 7, reference numerals C1 and C2 are first and second capacitors, and reference numerals Sw1 and Sw2 are first and second switches. When the combination of the capacitors C1 and C2 is made to correspond to the capacitor C of FIG. 3, the configuration of this embodiment basically matches the embodiment shown in FIG.
In this embodiment, a plurality of capacitors C1 and C2 and switches Sw1 and Sw2 for switching connection between the capacitors C1 and C2 are provided, and the plurality of capacitors C1 and C2 are connected in parallel or in series by switching the switches Sw1 and Sw2. To be able to connect to. Capacitors C1 and C2 are connected between another line and the ground with respect to the power supply line from the battery 2 to the booster circuit 3, and the semiconductor switching element S1 (switch means) and the relay Re (switch means) are connected. Via the input side of the booster circuit 3.
As the capacitors C1 and C2, for example, capacitors having a capacity of 10F and an operating voltage of 25V are used. The switches Sw1 and Sw2 are not particularly limited as long as they can be controlled.

  Initially, the switches Sw1 and Sw2 are switched as shown in FIG. 6, and the capacitors C1 and C2 are connected in parallel to ground from another line. As in the case of FIG. 3, in this embodiment, the capacitors C1 and C2 are connected to the diode D1 and the resistor by the output of the booster circuit 3 when the output voltage of the booster circuit 3 is higher than the voltage of the capacitor C1 or C2. The battery R is always charged via the device R.

  The capacitor output control device 4 monitors the voltages of the capacitors C1 and C2, and turns on the relay Re when the voltage exceeds a predetermined value. Then, when the output voltage of the battery 2 becomes lower than the reference voltage (11V), the semiconductor switching element S1 is turned on, and the power of the capacitors C1 and C2 is supplied to the input of the booster circuit 3. In this state, when the voltages of the capacitors C1 and C2 are sufficiently high and the output voltage of the battery 2 becomes lower than the reference voltage, the power of the capacitors C1 and C2 is automatically supplied to the input of the booster circuit 3.

The capacitor output control device 4 also monitors the voltages of the capacitors C1 and C2, and switches the switches Sw1 and Sw2 as shown in FIG. 7 when the voltages of the capacitors C1 and C2 are lowered with the assistance of the booster circuit 3. Then, the connection of the capacitors C1 and C2 is changed from the other line to the series with respect to the ground. As a result, the terminal voltages of the capacitors C1 and C2 are almost double that of the parallel connection. Therefore, it is possible to compensate for the voltage drop of the capacitors C1 and C2 for a while and continue to supply power to the booster circuit 3.

As described above, the present invention has been described with reference to some embodiments. By combining these embodiments, the power to the booster circuit input by the capacitor is more reasonable, safer and more effective. Can assist. Since a capacitor is used, the capacity can be selected according to the purpose, the charge amount can be accurately grasped, and the voltage can be varied even during operation, so that control according to the situation can be performed freely. As a result, the steering assist by the electric power steering apparatus can be effectively performed without waste. The present invention is also applicable to a steer-by-wire (Steer_By_Wire) in which the steering wheel and the front wheels in the steering system S are mechanically separated.
Furthermore, the apparatus can be made small, inexpensive, long life, and maintenance-free. By using this power supply device, the burden on the battery can be averaged, fluctuations in the output voltage of the battery and noise can be reduced, and furthermore, the electric current supplied to the electric power steering device can be reduced to reduce the electric power The steering device and the motor can be reduced in size and weight.

  Since the electric power steering device of the present embodiment is configured as described above, it can be used for a vehicle having an electric power steering device, particularly in terms of reduction in size and weight, and can be widely used for passenger vehicles and the like. it can.

It is a block diagram which shows the structure of the electric power steering apparatus of this invention. It is a circuit block diagram of the power supply control device which comprises the electric power steering device which is one embodiment of this invention. It is a circuit block diagram of the power supply control apparatus which comprises the electric power steering apparatus which is other embodiment of this invention. It is a circuit block diagram of the power supply control apparatus which comprises the electric power steering apparatus which is further another embodiment of this invention. It is a circuit block diagram of the power supply control apparatus which comprises the electric power steering apparatus which is further another embodiment of this invention. It is a circuit block diagram of the power supply control apparatus which comprises the electric power steering apparatus which is further another embodiment of this invention. FIG. 7 is a diagram illustrating a state in which a switch is switched in the circuit block diagram illustrated in FIG. 6. It is a block diagram of the conventional power supply device for electric power steering.

Explanation of symbols

1, 1a, 1b, 1c, 1d, 1e Power control device 2 Battery 3 Boosting circuit (boosting means)
4 Capacitor output control device (discharge power control means)
5 Input current control discharge control circuit (supply power control means, discharge power control means)
6 Charging Current Control Circuit 7 Control Information 8 Power Control Means 9 Drive Mechanism 10, 10a, 10b, 10c, 10d, 10e Electric Power Steering Device 11 Steering Handle 12 Steering Shaft 13 Pinion 14 Rack Shaft 15 Rack Pinion Mechanism 17 Front Wheel 19 Motor 20 Torque sensor (steering input detection means)
21 Vehicle speed sensor 22 Control circuit (control means)
25 Power supply 31, 33 Battery 32 Booster C, C1, C2 Capacitors (capacitance means)
D1, D2 Diode (diode means)
Q Voltage comparison circuit R, R1, R2 Resistor Re Relay (switch means)
S, S1 to S3 Semiconductor switching element (switch means)
Sw1, Sw2 switch Vr reference voltage

Claims (6)

An electric power steering device that calculates a target current based on at least an output signal from a steering input detection means and controls a motor by the target current,
Boosting means for boosting the output voltage of the battery and applying it to the motor;
Capacitance means that is provided so as to be able to supply power to the boosting means and discharges power;
Discharge power control means for controlling discharge from the capacity means to the boosting means;
Supply power control means for controlling power supply to the boosting means of the battery;
An electric power steering apparatus comprising: The electric power steering apparatus according to claim 1, wherein the discharge power control means discharges from the capacity means to the boosting means when a discharge current from the battery increases . 3. The electric power steering apparatus according to claim 1, further comprising power control means for controlling charging of the capacity means from the output of the boosting means. 4. The electric power steering apparatus according to claim 3 , wherein the power control unit increases the charging power when a charging voltage of the battery decreases or when a voltage output from the boosting unit decreases. . The capacity means is arranged on a line different from the power supply line connecting the battery and the boosting means,
The other line has one end connected to the capacity means from the output side of the boosting means, and the other end via switch means that is turned on when the output voltage or current of the battery is lower than a reference value. the electric power steering apparatus according to any one of claims 1 to 4, characterized in that it is connected to the input side of the booster means. 6. The electric power steering apparatus according to claim 5 , further comprising switching means for switching the connection between the plurality of capacity means and the another line in parallel or in series.

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