0001]The present invention is to vector control in the dq-axis rotating coordinate system driving the 3-phase brushless motor, a plurality of dead time compensation function (eg dead time compensation function of the inverter based on the function of the motor rotational angle (electrical angle) and the current command inverter based on the value model dead time compensation function) switching (conditional branch at a predetermined condition), by carrying out the dead time compensation according to the steering state, no improved steering performance, smooth steering sound assist It enables control and the related electric power steering apparatus. BACKGROUND [0002] 　Steering assist force by the rotation force of the motor to a steering mechanism of a vehicle electric power steering apparatus which provides (assist force) (EPS) is the driving force of the motor as an actuator, a transmission mechanism such as gears or a belt via reduction gear the, so as to impart a steering assist force to a steering shaft or a rack shaft. Such conventional electric power steering apparatus, in order to accurately generate a torque of the steering assist force, and performs a feedback control of a motor current. The feedback control is the difference between the steering assist command value (current command value) and the motor current detection value to adjust the voltage applied to the motor so as to reduce, adjustment of the voltage applied to the motor, generally a PWM (Pulse Width modulation) is performed by adjustment of the control of the Duty. [0003] 　To describe the general construction of an electric power steering apparatus shown in FIG. 1, column shaft of the handle 1 (steering shaft, the steering wheel shaft) 2 is a reduction gear 3, universal joints 4a and 4b, a pinion rack mechanism 5, tie rods 6a, through 6b, it is connected further hub unit 7a, via 7b steering wheels 8L, the 8R. In addition, the column shaft 2, a steering angle sensor 14 for detecting a steering angle of the steering wheel 1 theta, a torque sensor 10 for detecting is provided a steering torque Th of the steering wheel 1, to assist the steering force of the steering wheel 1 motor 20 is connected to the column shaft 2 via the reduction gear 3. The control unit (ECU) 30 for controlling the electric power steering apparatus, the electric power from the battery 13 is supplied, the ignition key signal is inputted through the ignition key 11. Control unit 30 performs the calculation of the assist (steering assist) command current command value based on the vehicle speed Vs detected by the steering torque Th and the vehicle speed sensor 12 detected by the torque sensor 10, the calculated current command value controlling the current supplied to the motor 20 by the voltage control command value Vref subjected to compensation for the. Steering angle sensor 14 is not mandatory and may not be disposed, may be from the rotation sensor such as a resolver connected to the motor 20 to obtain the θ steering angle (motor rotation angle). [0004] 　The control unit 30, CAN (Controller Area Network) 40 for exchanging various kinds of information of the vehicle and is connected, the vehicle speed Vs is also possible to receive from CAN40. Further, the control unit 30, communications other than CAN40, an analog / digital signal, even non CAN41 for exchanging radio waves connectable. [0005] 　In such an electric power steering device, it is constituted by the control unit 30 mainly CPU (including MPU or MCU etc.), indicating the general functions executed by a program in the CPU, for example, in FIG. 2 It has a configuration as shown. [0006] 　To explain the function and operation of the control unit 30 with reference to FIG. 2, the vehicle speed Vs from the steering torque Th and the vehicle speed sensor 12 from the torque sensor 10 is inputted to the steering assist command value calculating section 31, the steering assist command value calculation part 31 calculates the steering assist command value Iref1 using an assist map or the like based on the steering torque Th and the vehicle speed Vs. Limiting calculated steering assist command value Iref1 in the addition unit 32A, is added to the compensation signal CM from the compensator 34 to improve the characteristics, the steering assist command value Iref2 that are subject to the maximum value by the current limiting unit 33 is the maximum value the current command value is limited to Irefm is inputted to the subtraction unit 32B, is subtracted and the motor current detection value Im. [0007] 　A subtraction result of the subtraction unit 32B deviation ΔI (= Irefm-Im) is a current control such as PI (proportional integral) with PI (Proportional-Integral) control unit 35, the voltage control command value Vref, which is the current control modulated signal with (triangular wave carrier) CF is input to the PWM control unit 36 ​​is calculated the Duty command value, via the inverter 37 at the calculated PWM signal Duty command value to PWM drive the motor 20. Motor current value Im of the motor 20 is detected by a motor current detector 38, is inputted to the subtraction unit 32B by feedback. [0008] 　Compensation unit 34 adds the inertia compensation value 342 by an adder 344 to detect or estimated self aligning torque (SAT), by adding the convergence control value 341 in further addition unit 345 to the addition result, the addition the results were input to the addition unit 32A as the compensation signal CM, implementing the performance improvement. [0009] 　Recently, with the actuator of the electric power steering apparatus is a three-phase brushless motor has become a mainstream, because the electric power steering system is a vehicle products, wide operating temperature range, the inverter home electronics for driving the motor in terms of fail-safe products in comparison with the general industrial use to the representative, it is necessary to increase the dead time (industrial equipment I cm1 increases linearly (or non-linear) to) a predetermined current I cm @ 2 constant gain G above cc2 hold it is a characteristic that. The predetermined current I cm1 may be 0. [0049] 　Compensating the code estimating unit 202, the current command value I is input cm relative to output a compensation code SN shown in FIG. 12 (A) and the positive hysteresis characteristic shown in (B) (+1) or negative (-1). Current command value I cm is to estimate the compensation code SN as a reference point to the zero crossing, and has a hysteresis characteristic for the chattering suppressing. Estimated compensation code SN is input to the multiplier 203. Incidentally, (± 0.25 [A] in the example of FIG. 12) the positive and negative threshold of the hysteresis characteristic can be changed as appropriate. [0050] 　Current command value sensitive gain G from the current command value sensitive gain portion 250 c is input to the multiplier 203, the multiplication unit 203 compensates sign current command value obtained by multiplying the SN sensitive gain G cs (= G c × SN) output to. Current command value sensitive gain G cs is input to the multiplier 204d and 204q. [0051] 　Since the optimum dead time compensation amount is changed according to the inverter application voltage VR, calculates a dead time compensation amount corresponding to the inverter application voltage VR, so that variable. Voltage sensitive gain G to enter the inverter application voltage VR v inverter application voltage sensing gain unit 220 that outputs is as shown in FIG. 13, the inverter application voltage VR is limited to the positive and negative maximum value at the input limiting unit 221, the maximum inverter application voltage VR is limited to the value l is input to the inverter application voltage / time compensation gain conversion table 222. Characteristics of the inverter application voltage / time compensation gain conversion table 222, for example, as in FIG. 14. An inverter applied voltage 9.0V and 15.0V inflection point, voltage sensitive gain "0.7" and "1.2" is an example, can be appropriately changed. Voltage sensitive gain G v is the multiplication unit 231U, 231V, is input to 231W. [0052] 　Or early dead time compensation timing by the motor rotation speed omega, if you want to slow down, and a phase adjustment unit 210 for the function to calculate the adjustment angle in accordance with the motor rotational speed omega. The phase adjusting section 210, in the case of the advance angle control is a characteristic as shown in FIG. 15, the calculated phase adjustment angle Δθ is input to the adder 221, is added to the motor rotational angle θ that is detected. The addition result is a motor rotation angle theta of the adder 221 m (= theta + [Delta] [theta]) is the angle - dead time compensation value function unit 230 U, 230V, is input to the 230 W, are inputted to the 3-phase AC / dq axis conversion section 240 that. [0053] 　Angle - dead time compensation value function unit 230 U, 230V, 230 W, as shown in detail in Figure 16, the motor rotational angle θ is phase adjusted m against, 120 [deg in the range of electrical angle 0 ~ 359 [deg] ] by the phase-shifted square wave phase dead time reference compensation value U dt , V dt , W dt and outputs a. Dead time compensation value angle function unit 230 U, 230V, 230 W, the dead time compensation value required at three phases as a function depending on the angle, calculated on real time ECU, the dead time reference compensation value U dt , V dt , W Dt to output. Angle function of the dead time reference compensation value is different depending on the characteristics of the dead time of the ECU. [0054] 　Dead time reference compensation value U dt , V dt , W dt Each multiplier unit 231U, 231V, is input to 231W, the voltage sensitive gain G v is multiplied with. Voltage sensitive gain G v multiplied three phase dead time compensation value U dtc (= G v · U dt ), V dtc (= G v · V dt ), W dtc (= G v · W dt ) is 3 is input to the phase AC / dq axis conversion section 240. 3-phase AC / dq axis conversion section 240, the motor rotation angle theta m in synchronization with the three-phase dead time compensation value U dtc , V dtc , W dtc the dq axes of the two-phase dead time compensation value v Da * and V Qa * to convert to. Dead time compensation value v da * and v qq * are input to respective multipliers portion 204d and 204q, the current command value sensitive gain G cs is multiplied with. Multiplication result of the multiplying unit 204d and 204q dead time compensation value v d * and v q * is, the dead time compensation value v d * and v q * voltage command value in each adding section 121d and 121q are v d and v q is added to the voltage command values v d ** and v q ** is input to the space vector modulation section 300 as. [0055] 　It will now be described with reference to FIG. 17 for the dead time compensation section (B) 400. [0056] 　Dead time compensation unit 400, addition unit 401, the multiplication unit 402, an inverter application voltage sensitive compensation amount calculating section 410,3 phase current command value model 420, the phase current compensation code estimating unit 421, the phase adjusting unit 430,3 phase AC / It is composed of a dq axis conversion section 440. Incidentally, it constitutes a dead time compensation value output section in the multiplication unit 402 and the three-phase AC / dq axis conversion section 440. Motor rotational angle θ is inputted to the adder 401, the motor rotation speed ω is input to the phase adjuster 430. The inverter application voltage VR is input to an inverter application voltage sensitive compensation amount calculation unit 410, the motor rotational angle θ after the phase adjustment calculated by the addition unit 401 m is input to the 3-phase current command value model 420. [0057] 　Or early dead time compensation timing by the motor rotation speed omega, if you want to slow down, and a phase adjustment unit 430 for the function to calculate the adjustment angle in accordance with the motor rotational speed omega. Phase adjustment section 430, in the case of the advance angle control is a characteristic as shown in FIG. 15, the calculated phase adjustment angle Δθ is input to the adder 401, it is added to the motor rotational angle θ that is detected. The addition result is a motor rotation angle after the phase adjustment theta adder 401 m (= theta + [Delta] [theta]) is inputted to the 3-phase current command value model 420 is input to the 3-phase AC / dq axis conversion section 440. [0058] 　Detects the motor electrical angle by computing the Duty command value, there is a time lag of several tens to hundred [.mu.s] until it is actually reflected in the PWM signal. During this time, the motor is rotating, the phase shift occurs in the motor electric angle at the time of operation and the motor electric angle at the time of reflection. Therefore to compensate for the phase shift, it performs advance in accordance with the motor rotational speed omega, which adjusts the phase. [0059] 　Optimum dead time compensation amount because changes in accordance with the inverter application voltage VR, calculates a dead time compensation amount DTC corresponding to the inverter application voltage VR, so that variable. Inverter application voltage sensitive compensation amount calculation section 410 which enter the inverter application voltage VR and outputs the dead time compensation amount DTC is the same configuration as FIG. 13, the positive and negative inverter application voltage VR at input limiting section (corresponding to 221) is limited to a maximum value, limit the maximum inverters applied voltage (VR l corresponding to) is input to the inverter application voltage / dead time compensation amount conversion table (corresponding to 222). Characteristics of the inverter application voltage / dead time compensation amount conversion table 222, for example, as in Figure 18. That is, a certain dead time compensation amount DTC1 to a predetermined inverter applied voltage VR1, increases linearly (or non-linear) from a predetermined inverter application voltage VR1 to a predetermined inverter application voltage VR2 (> VR1), at a predetermined inverter application voltage VR2 higher is a characteristic which outputs a constant dead time compensation amount DTC2. [0060] 　d-axis current command value i d * and the q-axis current command value i q * is the motor rotation angle theta m with, is input to the 3-phase current command value model 420. 3-phase current command value model 420, dq axis current command value i d * and i q * , the motor rotational angle theta m from 120 as shown in FIG. 19 [deg] by a phase-shifted sinusoidal three-phase current model command value I cm to be calculated by the calculation or table (see below having 2 to several 3). 3-phase current model command value I cm is different by motor type. d-axis current command value i Ref_d and q-axis current command value i Ref_q the motor electric angle theta e is converted into a current command value of three phases from the (U · V · W-phase), the following equation 2. [0061] [Number 2] When obtaining the 3-phase current command value from the number 2, U-phase current command value model i Ref_u , V-phase current command value model i REF_V and W-phase current command value model i Ref_w are respectively the following equation 3 It represented. [0062] [Equation 3] 　table, even types that are stored in EEPROM (Electrically Erasable and Programmable Read- Only Memory), may be a type that is developed on the RAM (Random Access Memory). In use of the number 3 in advance as a table of sinθ only, the input θ by 90 ° offset or calculates cosθ by using, in such as by 120 ° offset, be calculated other sin function terms good. Or no problem in ROM capacity, for complex instruction value model (e.g., pseudo-rectangular wave motor), keep a table of the entire formula. [0063] 　3-phase current model command value I cm is input to the phase current compensation code estimator 421. Phase current compensation code estimating unit 421 three-phase current model command value I is input cm respect, compensation code shown in FIG. 12 (A) and the positive hysteresis characteristic shown in (B) (+1) or negative (-1) and it outputs the SN. 3-phase current model command value I cm to estimate the compensation code SN as a reference point to the zero crossing, but a hysteresis characteristic for the chattering suppressing. Estimated compensation code SN is input to the multiplier 402. Incidentally, the positive and negative thresholds of the hysteresis characteristic can be appropriately changed. [0064] 　If you decide the sign of the dead time compensation value simply from the current sign of the phase current command value model, chattering occurs in the low load. For example, when you turned the steering wheel to the left and right lightly in the on-center, torque ripple is generated. Therefore to improve the problem of hysteresis is provided to the code determination (in FIG. 12 ± 0.25 [A]), except if the sign exceeds the current value set is changed, suppressing chattering holds the current code to. [0065] 　Dead time compensation amount DTC from the inverter application voltage sensitive compensation amount calculation unit 410 is input to the multiplier 402, the multiplication unit 402 outputs the dead time compensation amount DTCa obtained by multiplying the compensation code SN (= DTC × SN). Dead time compensation amount DTCa is inputted to the 3-phase AC / dq axis conversion section 440, three-phase AC / dq axis conversion section 440, the motor rotation angle theta m dead time compensation value of two phases in synchronism with the v d * and V Q * outputs a. Dead time compensation value v d * and v q * is in each adder section 121d and 121q voltage command value v d and v q is added to the dead time compensation of the inverter 161 is performed. [0066] 　Thus, in the present invention, the dead time compensation value of the inverter dead time compensation function based on the function corresponding to the motor rotational angle (electrical angle) (A) and dead time compensation function based on the current command value model (B) switching at a predetermined condition, and to compensate the feed-forward to the dq axis. The dead time compensation value and 3-phase function corresponding to the motor rotational angle (electrical angle), by converting the three-phase / dq-axis are configured to compensate the feed-forward voltage command value on the dq axis. Therefore, as shown in FIG. 20, it is possible to implement optimum dead time compensation by switching different compensation function A and B instantly. [0067] 　Next, a description will be given space vector modulation. Space vector modulation section 300, as shown in FIG. 21, 2-phase voltage (v a dq-axis space d ** , v q ** ) the three-phase voltage converter (Vua, Vva, Vwa), the 3-phase voltages ( Vua, Vva, may have a function of superimposing the third harmonic in Vwa), for example, JP 2017-70066 by the present applicant, the space vector modulation proposed in Japanese Patent application No. 2015-239898 or the like method it may also be used. [0068] 　That is, space vector modulation, the voltage command values of dq-axis spatial v d ** and v q ** , based on the motor rotational angle θ and sector number n (# 1 ~ # 6) , the coordinate transformation as shown below was carried out, the bridge structure of the inverter of the FET (the upper arm Q1, Q3, Q5, lower arm Q2, Q4, Q6) for controlling the oN / OFF of the switching patterns S1-S6 corresponding to the sector # 1 to # 6 by supplying to the motor, it has a function of controlling the rotation of the motor. The coordinate transformation, in the space vector modulation, the voltage command value v d ** and v q ** , based on the number 4, the coordinate transformation is performed on the voltage vector Vα and Vβ of alpha-beta coordinate system. The relationship between the coordinate axes and motor rotation angle θ used in the coordinate transformation is shown in Figure 22. [0069] [Expression 4] Further, between the target voltage vector in the target voltage vector and alpha-beta coordinate system in d-q coordinate system, there is the relationship such as the number 5, the absolute value of the target voltage vector V is stored It is. [0070] [Equation 5] 　In the switching pattern in the space vector control, the output voltage of the inverter in accordance with a switching pattern S1 ~ S6 of FET (Q1 ~ Q6), 8 types of discrete reference voltage vector shown in the space vector diagram of FIG. 23 V0 ~ defined by V7 (π / 3 [rad] by different non-zero voltage vector V1 ~ V6 phases and zero voltage vector V0, V7). Then, so as to control the selection and its time of occurrence of their reference output voltage vector V0 ~ V7. Further, by using the six regions sandwiched by the adjacent reference output voltage vector, it is possible to divide the space vector into six sectors # 1 to # 6, target voltage vector V, sector # 1 to # 6 belong to one can be assigned a sector number. Vα and the target voltage vector V is the resultant vector of Vβ is, whether present in any sector, as shown in Figure 23, separated in a regular hexagon in alpha-beta space, the target voltage vector V alpha it can be obtained based on the rotation angle γ in -β coordinate system. Further, the rotation angle gamma voltage command value v in the rotational angle theta and d-q coordinate system of the motor d ** and v q ** as the sum of the obtained from the relationship phase [delta], is determined by γ = θ + δ. [0071] 　Figure 24 is a digital control by the inverter switching pattern S1, S3, S5 in space vector control, in order to output the target voltage vector V from the inverter, the switching pulse in the ON / OFF signals S1 ~ S6 (switching pattern) for FET It shows a basic timing chart to determine the width and its timing. Space vector modulation, performs like operation on each defined sampling period Ts in the sampling period Ts, converts the operation result in the next sampling period Ts, the switching pulse width in the switching patterns S1 ~ S6 and its timing to and output. [0072] 　Space vector modulation, and generates a switching pattern S1 ~ S6 corresponding to the sector number obtained based on the target voltage vector V. FIG 24, in the case of sector number # 1 (n = 1), an example of a switching pattern S1 ~ S6 of inverter FET is shown. Signals S1, S3 and S5 shows a gate signal corresponding to the upper arm FET Q1, Q3, Q5. The horizontal axis represents time, Ts corresponds to the switching period is divided into 8 time, T0 / 4, T1 / 2, T2 / 2, T0 / 4, T0 / 4, T2 / 2, T1 / 2 and a period consisting of T0 / 4. Moreover, the period T1 and T2 is the time that depends on the sector number n and the angle of rotation γ respectively. [0073] 　If there is no space vector modulation, a dead time compensation of the present invention is applied onto the dq axis, the dead time compensation value only dq axis / three-phase conversion the dead time compensation value waveform (U-phase waveform) is indicated by a broken line in FIG. 25 tertiary components such as becomes a waveform which is removed. The same applies to the V-phase and W-phase. By applying the spatial vector modulation instead of the dq-axis / three-phase converter, it can be superimposed on the third harmonic to the 3-phase signal and it can compensate for third-order components become deficient by three-phase conversion , it is possible to generate an ideal dead time compensation waveform shown in solid line in FIG. 25. [0074] 　Figure 26 shows experimental results by the steering experimental apparatus showing the effect of the present invention, in a steering state that the additional turning from medium speed to high speed steering, d when switched from the compensation function A to the compensation function B and axis current and the q-axis current, it shows the waveform of the q-axis dead time compensation value and the q-axis dead time compensation value. By dead time compensation value adapts the dead time compensation of the present invention as shown in FIG. 26 is switched from A to B, such as when to start flowing d-axis current, the influence of the dead time even when the current control characteristic is changed it can be confirmed that the waveform distortion of the dq-axis current due to the absence of. [0075] 　Figure 27 is a dead time compensation section of another example of (A) 200 is shown in correspondence with FIG. 7, the dead time compensation value v of the direct dq axis in the present embodiment da and v qa reference table 260d and 260q in are calculated. dq axis angle - as detailed in the dead time compensation value reference table 260d and 260q is 28, on off-line, and calculates the dead time compensation value which is a function of the angle which is required in three phases, on the dq axis converting the dead time compensation value. In other words, each phase angle - dead time compensation value function unit 260 U, 260 V, a motor rotation angle θ is phase adjusted by the 260 W m contrast, in the range of electrical angle 0 ~ 359 [deg] 120 of [deg] by a phase shift respective phase dead time reference compensation value U of the rectangular wave dt , V dt , W dt and outputs a. Dead time compensation value angle function unit 260 U, 260 V, 260 W is calculated in off-line time compensation values required in three phases as a function depending on the angle, the dead time reference compensation value U dt , V dt , W dt output to. Dead time reference compensation value U dt , V dt , W dtThe angle function varies according to the characteristics of the dead time of the ECU. [0076] 　Dead time reference compensation value U dt , V dt , W dt is inputted to the 3-phase AC / dq axis conversion section 261, dq axis dead time compensation value DT of the output waveform as shown in FIG. 28 d , DT q converted into It is. Based on the dq axis output waveform of FIG. 28, the angle (theta m angle by) input - generating a dead time compensation value reference table 240d and 240Q. Dead time compensation value criterion table 240d, as shown in FIG. 29 (A), the motor rotation angle theta m has a saw tooth output voltage characteristic (d axis dead time reference compensation value) with respect to the dead time compensation value criterion table 240q, as shown in FIG. 29 (B), and an output voltage characteristic of the wave waveform obtained by adding an offset voltage (q-axis dead time reference compensation value). [0077] 　Angle - dead time compensation value reference table 260d and the output voltage v indicates a dead time reference compensation value from 260Q da and v qa are input to respective multipliers portion 205d and 205Q, the voltage sensitive gain G v is multiplied with. Voltage sensitive gain G v dead time compensation value multiplied dq axis v da * and v qa * are input to respective multipliers portion 204d and 204q, the current command value sensitive gain G cs is multiplied with. Multiplication result of the multiplying unit 204d and 204q dead time compensation value v d * and v q * is, the dead time compensation value v d * and v q * voltage command value in each adding section 121d and 121q are v d and v q and it is added to the. DESCRIPTION OF SYMBOLS [0078] 1 handle 2 column shaft (steering shaft, the handle shaft) 10 torque sensor 12 vehicle speed sensor 20, 100 motor 30 control unit (ECU) 31 steering assist command value calculator 35,203,204 PI controller 36,160 PWM controller 37 , 161 inverter 110 angle detector 130 three-phase AC / dq axis conversion section 140 dq decoupling control unit 200 the dead time compensation unit (A) 201 current control delay model 202 compensates code estimator 210,430 phase adjustment unit 220 inverter applied voltage sensing gain unit 230U, 230V, 230W angle - dead time compensation value function unit 240, 440 three-phase AC / dq axis conversion section 250 current command value sensitive gain section 300 spatial vector modulation section 301 2-phase / 3-phase conversion unit 302 third harmonic superposition unit 400 dead time compensation section (B) 420 3-phase current command value model 421 phase current compensation code estimating unit 500 compensates value changeover portion 501 conditional branch unit 510 switching determination unit WE CLAIM At least calculates the steering assist command value of the dq-axis on the basis of the steering torque, the calculating the dq-axis current command value from the steering assist command value, and converting the dq-axis current command value to the Duty command value of the three-phase, PWM the three-phase brushless motor is driven and controlled by the control of the inverter, an electric power steering apparatus of a vector control method for imparting assist torque to a steering mechanism of a vehicle, a plurality of dead time compensation function of different performances to perform the dead time compensation of the inverter the a, electric power steering apparatus which comprises carrying out the dead time compensation is switched under a predetermined condition from the plurality of dead time compensation function one to another dead time compensation function. [Requested item 2] Said plurality of dead time compensation function is two, is effective in the slow-medium speed steering condition, a dead time compensation function A of the inverter based on the function of the motor rotational angle, it is effective in a high-speed steering condition, the current the electric power steering apparatus according to claim 1 which is a dead time compensation function B of the inverter based on a command value model. [Requested item 3] Wherein the predetermined condition is an electric power steering apparatus according to claim 1 or 2 which is a switching condition determined by the dq-axis current command value and motor speed. [Requested item 4] The dead time compensation function A and the switching of the dead time compensation function B, the electric power steering apparatus according to claim 3, carried out by the conditional branch of the software based on the switching condition. [Requested item 5] It calculates a steering assist command value of the dq-axis on the basis of at least steering torque, the steering of the dq-axis current command value from the assist command value is calculated, and converts the dq axis current command value to the three-phase Duty command value, PWM control inverter the drives and controls the three-phase brushless motor, an electric power steering apparatus of a vector control method for imparting assist torque to a steering mechanism of the vehicle, relating to the dq axis of said inverter based on the motor rotation angle of the three-phase brushless motor a dead time compensation unit a for calculating a first dq axis compensation value, and inputs the dq-axis current command value, calculates the second dq axis compensating value for the dq axis of said inverter based on the current command value model dead time compensation section B and, on the basis of the said steering assist command value of the dq axis current command value and the q-axis first dq axis compensation value Said second switching between dq-axis compensation value and the compensation value switching section outputs the dq-axis dead time compensation value, and comprises a, by correcting the dq-axis current command value by the dq-axis dead time compensation value electric power steering apparatus which comprises carrying out the dead time compensation of the inverter. [Requested item 6] The compensation value changeover portion is a switching determination unit for determining the compensation value switching based on the steering assist command value of the dq axis current command value and the q-axis, the switching determination flag from the switching determination unit, wherein a conditional branch portion for outputting a first dq axis compensation value or the second dq axis compensating value as said dq axis dead time compensation value, in the electric power steering apparatus according to claim 5 is constructed. [Requested item 7] The switching determination unit, and a zero determination unit outputs a determination flag 1 when the d-axis current command value becomes close to zero, the first absolute value unit for obtaining the absolute value of the q-axis current command value, wherein the output of the first absolute value unit outputs a second determination flag when it becomes equal to or greater than the first threshold value, a first threshold unit having a hysteresis characteristic, the motor rotation speed of the second obtaining an absolute value an absolute value unit, together with the output of said second absolute value unit outputs a third determination flag when it becomes equal to or greater than a second threshold value, a second threshold value unit having a hysteresis characteristic, the first determination flag, the second determination flag and the third and the switching condition determination unit for outputting the switching determination flag when the determination flag is input, the electric power steering apparatus according to claim 6 which is configured in. [Requested item 8] The electric power steering apparatus according to claim 7 wherein the near zero is 0.0 ~ 0.1 [A]. [Requested item 9] The conditional branch unit, an electric power steering device according to any one of claims 6-8 performed by the conditional branch of the software based on the switching determination flag. [Requested item 10] Said correction electric power steering apparatus according to any one of claims 5 to 9 wherein the dq axis dead time compensation value to be the addition operation of the dq-axis current command value