JP2020031469A - Motor drive control device - Google Patents

Abstract

To provide a motor drive control device capable of simply performing dead time compensation without detecting phase current of a motor, and processing complicated coordinate conversion.SOLUTION: According to a mother drive system 1, a dead time compensation unit 44 in a motor drive control device 4 comprises a compensation amount determination unit 441 for determining an absolute value of a compensation amount, based on a magnitude of a current command vector; and a timing production unit 442 for performing adjustment with respect to an electrical angle phase of a rotor, based on a phase of the current command vector, and for producing timing at which the absolute value of the compensation amount is added thereto and subtracted therefrom, based on polarity of the electrical angle phase from the foregoing adjustment result.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor drive control device.

  In an inverter circuit that outputs a drive voltage to a motor, the switching elements are normally turned on and off at the time of switching on and off of the switching elements in the upper and lower stages connected in series. A period in which both of the elements are turned off is provided. The above period is generally called dead time. At the timing of the dead time, current tends to continue to flow due to the inductance of the motor and the freewheeling diode of the inverter circuit. Then, depending on the direction in which the current flows, there is a difference between the voltage desired to be output from the inverter circuit to the motor and the voltage actually output to the motor. The above difference is hereinafter referred to as “output voltage error”. Conventionally, dead time compensation is generally performed to compensate for the output voltage error caused by providing a dead time.

  For example, in Patent Documents 1 and 2, the dead time compensation amount of each phase is added or subtracted from each of the three phase voltage command values, and each of the added or subtracted voltage command values is subjected to PWM (Pulse Width Modulation; pulse width). A technique is disclosed in which a dead time is compensated by inputting the signal to a modulation (modulation) circuit and turning on and off each switching element (for example, a transistor) of the inverter circuit by PWM control.

  In particular, in Patent Document 1, when performing dead time compensation, three-phase current command values iu *, iv *, iw * are calculated from two-phase current command values id *, iq *, and three-phase current command values are calculated. A configuration is disclosed in which dead time compensation amounts ed (iu *), ed (iv *), and ed (iw *) are calculated using iu *, iv *, and iw *. Further, in Patent Document 1, the actual output current value (for three phases) of the inverter circuit is detected, and the two-phase current command values id * and iq * and the actual output current values (coordinate conversion from three phases to two phases) are performed. Current values), and outputs voltage command values ed * and eq * corresponding to the current errors, and converts the voltage command values ed * and eq * into three-phase voltage command values eu * and ev. *, Ew *, and adding the dead time compensation amounts ed (iu *), ed (iv *), ed (iw *) to the voltage command values eu *, ev *, ew *, respectively. I have.

  Further, in Patent Document 2, a voltage command is determined based on a determination result as to whether the PWM pulse is a section where the PWM pulse changes from on to off or a section where the PWM pulse changes from on to off, and a motor current detection value. A configuration in which a dead time compensation voltage is added or subtracted to generate a compensated voltage command is disclosed.

JP-A-9-261974 (refer to claims 1, paragraphs [0005] and [0010], FIG. 5, FIG. 9, etc.) JP 2011-55608 A (see claim 1, paragraphs [0021], [0022], [0025] to [0027], FIG. 1 and the like)

Conventionally, when performing dead time compensation, it is necessary to acquire an output current value of an inverter circuit (current detection value of a motor), in other words, to detect a phase current of a motor, as in Patent Documents 1 and 2. Further, in Patent Document 1, when performing dead time compensation, a complicated coordinate conversion process for converting two-phase current command values id ^* , iq ^* into three-phase current command values iu ^* , iv ^* , iw ^* is required. Met. For this reason, conventionally, dead time compensation could not be easily performed.

  In view of the above, an object of the present invention is to provide a motor drive control device that can easily perform dead time compensation without detecting a phase current of a motor and performing complicated coordinate conversion processing.

  An exemplary motor drive control device of the present invention converts a voltage command into a PWM pulse, and switches on / off each of the switching elements connected in series by the PWM pulse, so that the PWM inverter outputs a voltage to the motor. A motor drive control device that drives and controls the motor by giving the voltage command based on a current command vector indicating a current vector to be followed by a current flowing through the motor, wherein the current command vector is A vector defined in a coordinate system synchronized with the rotor, or a coordinate system equivalent thereto, which is generated by providing a dead time for avoiding simultaneous turning-on of the series-connected switching elements in the PWM inverter, Compensation amount for compensating the error of the output voltage of the PWM inverter Determined, and a dead time compensation unit for outputting the command voltage obtained by adding the compensation amount to the PWM inverter. The dead time compensating unit includes a compensation amount determining unit that calculates an absolute value of the compensation amount based on the magnitude of the current command vector, and an adjustment to an electrical angle phase of the rotor based on the phase of the current command vector. And a timing generator for generating a timing for adding or subtracting the absolute value of the compensation amount based on the polarity of the electrical angle phase as a result of the adjustment.

  According to the above configuration, dead time compensation can be easily performed without performing complicated coordinate conversion processing relating to detection of a phase current and a current command.

FIG. 1 is a block diagram illustrating an overall configuration of a motor drive system according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a configuration of a part of the motor drive system. FIG. 3 is an explanatory diagram showing an example of a waveform of a three-phase AC voltage applied to the motor of the motor drive system. FIG. 4 is an explanatory diagram showing a relationship between a voltage level of each phase voltage and a carrier signal in the PWM control, and a waveform of a PWM pulse applied to each switching element. FIG. 5A is an equivalent circuit around the armature winding at the timing T0 to T1 in FIG. FIG. 5B is an equivalent circuit around the armature winding at the timing T1 to T2 in FIG. FIG. 5C is an equivalent circuit around the armature winding at the timing T2 to T3 in FIG. FIG. 5D is an equivalent circuit around the armature winding at the timing T3 to T4 in FIG. FIG. 6A is an explanatory diagram showing an analysis model of the motor when θ is the phase of the d-axis with respect to the reference axis A. FIG. 6B is an explanatory diagram showing an analysis model of the motor when θ is the phase of the q axis with respect to the reference axis A. FIG. 7 is an explanatory diagram showing an example of a conventional method for obtaining a general dead time compensation amount. FIG. 8 is an explanatory diagram showing a method of obtaining a compensation amount in the embodiment of the present invention. FIG. 9 is an explanatory diagram schematically showing a current command vector. FIG. 10 is an explanatory diagram illustrating the compensation amount when the magnitude of the current command vector is equal to or greater than the current threshold. FIG. 11A is an explanatory diagram illustrating an example of a waveform of each phase current and a change with time of the electrical angle phase. FIG. 11B is an explanatory diagram illustrating a first shift step of the electrical angular phase for determining the polarity of the U-phase current. FIG. 11C is an explanatory diagram illustrating a second shift step of the electrical angular phase for determining the polarity of the U-phase current. FIG. 12 is an explanatory diagram showing a step of shifting the electrical angular phase for determining the polarity of the V-phase current. FIG. 13 is an explanatory diagram showing a step of shifting the electrical angular phase for determining the polarity of the W-phase current. FIG. 14 is an explanatory diagram illustrating an example of a waveform of the U-phase current and a change in the electrical angle phase with time when the rotation speed of the rotor is negative.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the value of the voltage command (voltage command value) is also simply referred to as a voltage command, and the value of the current command (current command value) is simply referred to as a current command.

<Schematic configuration of motor drive system>
FIG. 1 is a block diagram illustrating an overall configuration of a motor drive system 1 according to an exemplary embodiment of the present invention, and FIG. 2 is a circuit diagram illustrating a partial configuration of the motor drive system 1. The motor drive system 1 includes a motor 2, a PWM inverter 3, a motor drive control device 4, a DC power supply 5, and a position sensor 6. The details of the motor drive control device 4 will be described later. As shown in FIG. 2, the DC power supply 5 outputs a DC voltage between the positive output terminal 5a and the negative output terminal 5b with the negative output terminal 5b on the low voltage side.

  The motor 2 is composed of, for example, a three-phase brushless DC motor (BLDC motor). More specifically, as shown in FIG. 2, the motor 2 includes a rotor 21 provided with permanent magnets, and U-phase, V-phase and W-phase armature windings 22u, 22v and 22w. And a stator 22. Armature windings 22u, 22v, and 22w are Y-connected around neutral point 23. In the armature windings 22u, 22v and 22w, the non-connection ends opposite to the neutral point 23 are connected to the terminals 24u, 24v and 24w, respectively.

  The PWM inverter 3 includes a power unit 31 and a PWM circuit 32. The PWM circuit 32 performs PWM control of the power unit 31 based on the voltage commands Vu_ref ', Vv_ref', and Vw_ref 'output from the motor drive control device 4. The voltage commands Vu_ref ', Vv_ref' and Vw_ref 'are voltage commands that take into account the amount of dead time compensation obtained by a method described later.

  The power unit 31 includes a U-phase half-bridge circuit, a V-phase half-bridge circuit, and a W-phase half-bridge circuit. Each half-bridge circuit has a pair of switching elements. In each half-bridge circuit, a pair of switching elements are connected in series between the positive output terminal 5a and the negative output terminal 5b of the DC power supply 5, and a DC voltage from the DC power supply 5 is applied to each half-bridge circuit. Each switching element is formed of, for example, a field-effect transistor, but may be formed of another transistor such as an IGBT (insulated gate bipolar transistor).

  The U-phase half-bridge circuit includes a high-voltage switching element 33u and a low-voltage switching element 34u connected in series with each other. The V-phase half-bridge circuit includes a high-voltage-side switching element 33v and a low-voltage-side switching element 34v that are connected in series with each other. The W-phase half-bridge circuit includes a high-voltage switching element 33w and a low-voltage switching element 34w connected in series with each other.

  Diodes 35u, 35v, and 35w are connected in parallel to the high voltage switching elements 33u, 33v, and 33w, respectively, with the direction from the low voltage side of the DC power supply 5 toward the high voltage side being the forward direction. Similarly, diodes 36u, 36v, and 36w are connected in parallel to low-voltage-side switching elements 34u, 34v, and 34w, respectively, with the direction from the low-voltage side of DC power supply 5 toward the high-voltage side being the forward direction. Each of the diodes 35u, 35v, 35w, 36u, 36v, and 36w functions as a free wheel diode (freewheel diode).

  A connection point between the switching element 33u and the switching element 34u connected in series is connected to the terminal 24u. Similarly, a connection point between the switching element 33v and the switching element 34v connected in series is connected to the terminal 24v, and a connection point between the switching element 33w and the switching element 34w connected in series is connected to the terminal 24w.

  The PWM circuit 32 generates a PWM pulse (pulse width modulation signal) for each phase based on three-phase (U-phase, V-phase and W-phase) voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′, and generates the PWM pulse. To the control terminal (gate or base) of each switching element of the power unit 31. Accordingly, each of the switching elements can be switched between on (conduction) and off (non-conduction).

  Accordingly, the DC voltage from the DC power supply 5 is applied to the motor 2 by the switching operation of each switching element in accordance with the PWM pulse in the PWM inverter 3, whereby each armature winding 22 u of the motor 2 is applied. , 22v and 22w, a current corresponding to the three-phase voltage flows, and the motor 2 is driven. The relationship between the switching operation of each switching element and the current (phase current) flowing through the motor 2 will be described later.

  From the above, the PWM inverter 3 of the present embodiment converts the voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′ into a PWM pulse, and switches on / off each of the switching elements connected in series by the PWM pulse, whereby the motor 2 It can be said that the configuration is such that the voltage is output to

  The position sensor 6 shown in FIG. 1 is a sensor that outputs a signal according to the rotational position of the rotor 21 of the motor 2, and uses, for example, a rotary encoder or a Hall element. A signal output from the position sensor 6 is input to a motor drive control device 4 described later.

<Relationship between switching operation of each switching element and phase current>
Next, the relationship between the switching operation of each switching element in the power unit 31 of the PWM inverter 3 and the phase current of the motor 2 will be described. Hereinafter, for convenience of description, a line connecting each of the low-voltage switching elements 34u, 34v, and 34w in the power unit 31 and the negative output terminal 5b of the DC power supply 5 is referred to as a bus G. The current flowing through the bus G is referred to as a bus current. The currents flowing through the armature windings 22u, 22v, and 22w of the motor 2 are called a U-phase current, a V-phase current, and a W-phase current, respectively, and each of them (or collectively) is referred to as a phase current. Call. Regarding the polarity of the phase current, the polarity of the phase current flowing from the terminal 24u, 24v or 24w to the neutral point 23 is positive, and the polarity of the phase current flowing out of the neutral point 23 is negative.

  FIG. 3 is an explanatory diagram illustrating an example of a waveform of a three-phase AC voltage applied to the motor 2. In FIG. 3, 25u, 25v, and 25w represent waveforms of a U-phase voltage, a V-phase voltage, and a W-phase voltage to be applied to the motor 2, respectively. Each of the U-phase voltage, the V-phase voltage, and the W-phase voltage (or collectively) is also referred to as a phase voltage. When a sinusoidal current is passed through the motor 2, the output voltage of the PWM inverter 3 is sinusoidal.

  As shown in FIG. 3, the level relationship between the U-phase voltage, the V-phase voltage, and the W-phase voltage changes with time. The height relationship is determined by the three-phase voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′, and the PWM inverter 3 determines the energization pattern for each phase based on the three-phase voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′. I do.

  Here, there are the following eight types of the energization patterns. The first energization pattern is an energization pattern in which the switching elements 34u, 34v, and 34w on the low voltage side of the U, V, and W phases are all turned on. The second energization pattern is an energization pattern in which the W-phase high-voltage side switching element 33w is turned on and the U-phase and V-phase low-voltage side switching elements 34u and 34v are turned on. The third energization pattern is an energization pattern in which the V-phase high voltage side switching element 33v is turned on, and the W-phase and U-phase low voltage side switching elements 34w and 34u are turned on. The fourth energization pattern is an energization pattern in which the V-phase and W-phase high-voltage switching elements 33v and 33w are turned on, and the U-phase low-voltage switching element 34u is turned on. The fifth energization pattern is an energization pattern in which the U-phase high-voltage side switching element 33u is turned on and the V-phase and W-phase low-voltage side switching elements 34v and 34w are turned on. The sixth energization pattern is an energization pattern in which the W-phase and U-phase high-voltage switching elements 33w and 33u are turned on, and the V-phase low-voltage switching element 34v is turned on. The seventh energization pattern is an energization pattern in which the U-phase and V-phase high-voltage side switching elements 33u and 33v are turned on, and the W-phase low-voltage side switching element 34w is turned on. The eighth energization pattern is an energization pattern in which the U, V, and W phase high voltage side switching elements 33u, 33v, and 33w are all turned on.

  In addition, in the two switching elements of the same phase (connected in series), if a dead time for avoiding a short circuit due to simultaneous ON of the switching element on the high voltage side and the switching element on the low voltage side is neglected, The switching element on the low voltage side is off while the switching element on the side is on, and the switching element on the low voltage side is on while the switching element on the high voltage side is off.

  Actually, the above-mentioned dead time is provided at the time of switching on / off of each switching element. During the dead time period, the high-voltage side switching element and the low-voltage side switching element of the same phase are simultaneously turned off. Becomes Also, as described above, by providing the dead time, an error (output voltage error) occurs between the voltage output from the PWM inverter 3 to the motor 2 and the voltage (voltage command) to be output. . In the present embodiment, an error in the output voltage is compensated for by a dead time compensator 44 described later.

  FIG. 4 is an explanatory diagram showing the relationship between the voltage level of each phase voltage and the carrier signal and the waveform of a PWM pulse applied to each switching element when performing PWM control for three phases. Here, the dead time described above is ignored for the purpose of simplifying the description. In addition, “high voltage side SW” and “low voltage side SW” in FIG. 4 respectively indicate a high voltage side switching element and a low voltage side switching element. Although the level relationship between the voltage levels of the phase voltages varies in various ways, FIG. 4 focuses on an arbitrary timing 26 in FIG. That is, FIG. 4 shows a case where the voltage level of the U-phase voltage is the maximum and the voltage level of the W-phase voltage is the minimum.

  In FIG. 4, reference symbol CS represents a carrier signal to be compared with the voltage level of each phase voltage. The carrier signal is a periodic triangular wave signal, and the cycle of the signal is called a carrier cycle. Since the carrier cycle is much shorter than the cycle of the three-phase AC voltage shown in FIG. 3, if the triangular wave of the carrier signal shown in FIG. 4 is represented on FIG. 3, the triangular wave becomes a single line. I can see

  5A to 5D are equivalent circuits around the armature winding at each timing in FIG. The start timing of each carrier cycle, that is, the timing at which the carrier signal is at the lowest level is T0. At timing T0, the switching elements 33u, 33v, and 33w on the high voltage side of each phase are turned on.

  The period excluding the period between the timings T1 and T6 from the carrier period indicates the pulse width of the PWM pulse for the W-phase high-voltage side switching element, and the period between the carrier period and the timings T2 and T5. Represents the pulse width of the PWM pulse for the V-phase high-voltage side switching element. The period excluding the period between the timings T3 and T4 from the carrier cycle represents the U-phase high-voltage side switching. Indicates the pulse width of the PWM pulse for the element.

  In the above, the case where the magnitude relation of the voltage levels is in the order of U-phase voltage> V-phase voltage> W-phase voltage has been described as an example. However, even when the magnitude relation of the voltage levels is in another order, the same PWM as described above is used. By the control, the phase current of the motor 2 can be controlled.

<Counter control of voltage command>
The U-phase, V-phase and W-phase voltage commands Vu_ref ', Vv_ref' and Vw_ref 'are specifically expressed as count setting values CntU, CntV and CntW of a counter (timer) (not shown) in the PWM circuit 32. You. Then, the higher the phase voltage, the larger the count setting value is given. For example, in the case of FIG. 4, CntU>CntV> CntW holds.

  The above counter increments the count value from 0 based on the timing T0 for each carrier cycle. When the count value reaches CntW, the switching element 33w on the high voltage side of the W phase is switched from the ON state to the switching element 34w on the low voltage side. Subsequently, when the count value reaches CntV, the switching element 33v on the high voltage side of the V phase is switched from the on state to the switching element 34v on the low voltage side. After that, when the count value reaches CntU, the U-phase high voltage side switching element 33u is switched from the ON state to the low voltage side switching element 34u. After the carrier signal reaches the maximum level, the count value is down-counted, and the reverse switching operation is performed.

  When the triangular carrier signal shown in FIG. 4 is used, the count is returned from the up-count to the down-count at half the carrier cycle. The above up-count and down-count are performed in synchronization with a predetermined clock.

  The pulse width (and duty) of the PWM pulse for each phase is generated by the count setting values CntU, CnuV and CntW corresponding to the U-phase, V-phase and W-phase voltage commands Vu_ref ', Vv_ref' and Vw_ref '.

<About various definitions>
Next, before describing the details of the motor drive control device 4 described above, various definitions will be given below. 6A and 6B are explanatory diagrams illustrating an analysis model of the motor 2. FIG. The U-phase axis, the V-phase axis, and the W-phase axis are fixed axes, and are shifted from each other by 120 ° in electrical angle. 21a is a permanent magnet provided on the rotor 21 of the motor 2. In a rotating coordinate system that rotates at the same speed as the magnetic flux generated by the permanent magnet 21a, the direction of the magnetic flux generated by the permanent magnet 21a is set to the d-axis, and the q-axis is set to a phase advanced by 90 electrical degrees from the d-axis. A coordinate system having a d-axis and a q-axis is referred to as a dq coordinate system, and coordinates obtained by selecting the d-axis and the q-axis as coordinate axes are referred to as dq coordinates. The dq coordinate system is a coordinate system synchronized with the rotor 21 of the motor 2.

  In the dq coordinate at any instant of the rotating d-axis and q-axis, the phase of the d-axis or q-axis with respect to a certain reference axis A (fixed axis) is represented by θ (electrical angle phase). In the present embodiment, a certain reference axis A is defined as a U-phase axis, and the phase of the q-axis with respect to the U-phase axis is represented by θ (electrical angle phase). That is, the reference axis A corresponds to an electrical angle phase of 0 ° when, for example, the electrical angle phase of the rotor 21 is expressed in a range from −180 ° to + 180 °. In addition, assuming that a shift in electrical angle between the U-phase axis and the reference axis A is θa, the shift θa is determined by the motor drive control system 1 and is, for example, 0 ° in electrical angle in the present embodiment. The information on the deviation θa may be stored in a memory (not shown) of the motor drive control device 4, for example.

  The overall motor voltage applied to the motor 2 from the PWM inverter 3 is represented by Va, and the overall motor current supplied to the motor 2 from the PWM inverter 3 is represented by Ia. The d-axis component and the q-axis component of the motor voltage Va are represented by a d-axis voltage vd and a q-axis voltage vq, respectively. The d-axis component and the q-axis component of the motor current Ia are respectively represented by a d-axis current id and a q-axis current. Expressed as iq.

  Also, command values (voltage command values) for the d-axis voltage vd and the q-axis voltage vq are represented by a d-axis voltage command vd_ref and a q-axis voltage command vq_ref, respectively. The d-axis voltage command vd_ref and the q-axis voltage command vq_ref represent voltages (voltage values) to be followed by the d-axis voltage vd and the q-axis voltage vq, respectively, and are calculated in the motor drive system 1.

  Further, command values (current command values) for the d-axis current id and the q-axis current iq are represented by a d-axis current command id_ref and a q-axis current command iq_ref, respectively. The d-axis current command id_ref and the q-axis current command iq_ref represent currents (current values) to be followed by the d-axis current id and the q-axis current iq, respectively, and are calculated in the motor drive system 1.

<Details of motor drive control device>
The motor drive control device 4 will be described based on the above definition. The motor drive control device 4 shown in FIG. 1 is a control unit that controls the drive of the motor 2 using the PWM inverter 3, and includes a position detection unit 41, a current controller 42, a coordinate converter 43, and a dead time compensation. A part 44. The motor drive control device 4 includes, for example, a microcomputer having a central processing unit (CPU).

  The position detector 41 detects the electrical angle phase θ of the rotor 21 based on the output signal from the position sensor 6 described above. Information on the detected electrical angle phase θ is output from the position detection unit 41 to the coordinate converter 43 and the dead time compensation unit 44 as position information on the rotor 21.

  The current controller 42 converts the input d-axis current command id_ref and q-axis current command iq_ref into a d-axis voltage command vd_ref and a q-axis voltage command vq_ref and outputs the same to the coordinate converter 43.

  The coordinate converter 43 converts the d-axis voltage command vd_ref and the q-axis voltage command vq_ref input from the current controller 42 into U-phase, V-phase and W-phase voltage commands Vu_ref, Vv_ref and Vw_ref, respectively, and converts the dead time. Output to the compensator 44. From the position detection unit 41, information on the electrical angle phase θ of the rotor 21 is input to the coordinate converter 43, and the deviation θa in electrical angle between the U-phase axis and the reference axis A is also known in advance. From the relationship shown in FIGS. 6A and 6B, the coordinate converter 43 uses the electrical angle phase θ and the deviation θa of the rotor 21 to set each voltage command in the d-axis direction and the q-axis direction (two-phase voltage command). Is converted into coordinates in each direction of the U-phase axis, the V-phase axis, and the W-phase axis to obtain voltage commands (three-phase voltage commands) of the U, V, and W phases.

  The dead time compensating unit 44 compensates for an error in the output voltage of the PWM inverter 3 caused by providing a dead time for avoiding simultaneous ON of the switching elements connected in series in the PWM inverter 3. , And outputs a voltage command to the PWM inverter 3 in consideration of the compensation amount ΔVd. That is, the dead time compensator 44 adds or subtracts the compensation amount ΔVd for each phase from the U-phase, V-phase, and W-phase voltage commands Vu_ref, Vv_ref, and Vw_ref input from the coordinate converter 43. , And generates voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′ in consideration of the compensation amount ΔVd of each phase, and outputs them to the PWM inverter 3. Compensating the output voltage error caused by providing the dead time, that is, generating the voltage commands Vu_ref ′, Vv_ref ′ and Vw_ref ′ in consideration of the compensation amount ΔVd of each phase is called dead time compensation. Call.

  Here, FIG. 7 is an explanatory diagram showing a conventional method of obtaining a general compensation amount ΔVd. For example, in consideration of the compensation amount ΔVd for the U-phase, conventionally, an instantaneous value (instantaneous value) of the U-phase current is detected, and when the detected current is equal to or smaller than the threshold, the compensation amount ΔVd is proportional to the detected current value. Was decided. Then, the obtained compensation amount ΔVd is added to or subtracted from the U-phase voltage command to generate a voltage command in consideration of the compensation amount ΔVd. On the other hand, when the detected current exceeds the threshold, the compensation amount ΔVd is uniformly set to the fixed value ΔVd ′. In such dead time compensation, the detection of the phase current (the U-phase current in the above example) is required, so that the dead time compensation cannot be easily performed. The method of setting the compensation amount ΔVd is also disclosed in the above-mentioned Patent Document 2 (see FIG. 8 of Patent Document 2).

  On the other hand, FIG. 8 is an explanatory diagram showing a method for obtaining the compensation amount ΔVd in the present embodiment. In the present embodiment, the compensation amount determination unit 441 included in the dead time compensation unit 44 determines the compensation amount ΔVd based on the magnitude of the current command vector I_ref indicating the vector of the current that the current flowing through the motor 2 should follow. . Thus, dead time compensation can be easily performed without detecting the above-described phase current. Hereinafter, the dead time compensation of the present embodiment will be described in more detail. In the following, a case will be described as an example in which the compensation amount ΔVd is obtained for any phase (for example, the U phase) of the U phase, the V phase, and the W phase. ΔVd can be obtained.

FIG. 9 schematically shows the current command vector I_ref. The current command vector I_ref is a composite vector of the vector components of the aforementioned d-axis current command id_ref and q-axis current command iq_ref. Assuming that the magnitude of the current command vector I_ref is | I_ref |, | I_ref | is expressed by the following equation (1).
| I_ref | = {(id_ref) {2+ (iq_ref)} 2} (1)

Specifically, in the present embodiment, the compensation amount ΔVd is obtained as follows using | I_ref |. In FIG. 8, a current waveform corresponding to a phase current (for example, a U-phase current) is indicated by a dashed sine wave. Note that the current waveform is indicated by a broken line because, in the present embodiment, unlike the case of FIG. 7, no phase current is detected. | I_ref | corresponds to the amplitude of the current waveform of the phase current in FIG. Therefore, in the present embodiment, when the predetermined fixed value of the compensation amount is set to ΔVd ′ and the current threshold is set to is [A], the compensation amount determination unit 441 is obtained by the calculation of the following expression (2). ΔVd is determined as a compensation amount. However, it is assumed that | I_ref | is less than the current threshold value is.
ΔVd = ΔVd ′ × | I_ref (t) | / it (2)

  As shown in FIG. 8, the polarity of the compensation amount ΔVd is positive during a period in which the polarity of the phase current is positive (for example, a period from t0 to t1 and a period from t2 to t3), and the polarity of the phase current is negative. In a certain period (for example, a period from t1 to t2, a period from t3 to t4), the period is set to be negative. The polarity of the compensation amount ΔVd is determined by a method described later. In this case, the magnitude (absolute value) of the compensation amount ΔVd is determined first by Expression (2).

  In a period where the value of | I_ref | corresponding to the amplitude of the phase current is constant (in FIG. 8, a period of t0 to t2 and a period of t2 to t4), the compensation amount ΔVd (absolute value) is expressed by the equation (2). Take a constant value according to When | I_ref | is less than the current threshold value ith, for example, in the period from t2 to t4 when | I_ref | is smaller than the value in the period from t0 to t2, the compensation amount ΔVd is It is smaller than the value in the period. Conversely, in a period in which | I_ref | is larger than the value in the period from t0 to t2, the compensation amount ΔVd is larger than a value in the period from t0 to t2.

  FIG. 10 is an explanatory diagram showing the compensation amount ΔVd when | I_ref | is equal to or larger than the current threshold value it. When | I_ref | is equal to or greater than the current threshold it, the compensation amount determination unit 441 determines the fixed value ΔVd ′ as the compensation amount ΔVd. That is, in the equation (2), the current threshold value is used instead of | I_ref |. As a result, from equation (2), ΔVd = ΔVd ′. Therefore, the compensation amount ΔVd does not exceed the fixed value ΔVd ′ even when | I_ref | exceeds the current threshold value ith and increases.

  As described above, in the present embodiment, the dead time compensating unit 44 (compensation amount determining unit 441) calculates the compensation amount ΔVd based on the current command vector I_ref which is a composite vector of the d-axis current command id_ref and the q-axis current command iq_ref. , The detection of the phase current, which was conventionally required for dead time compensation, is not required. Further, in the above-mentioned Patent Document 1, when performing dead time compensation, two-phase current commands (for example, d-axis and q-axis current commands) are replaced with three-phase current commands (for example, U-phase, V-phase, and W-phase current commands). Although complicated coordinate conversion processing for conversion into each current command is required, the configuration of the present embodiment also eliminates such coordinate conversion processing for two-phase and three-phase current commands. Therefore, according to the configuration of the present embodiment, the compensation amount ΔVd can be easily obtained and the dead time can be easily compensated without performing the detection of the phase current and the complicated coordinate conversion process of the current command.

  In the above, a combined vector of the respective vector components of the d-axis current command id_ref and the q-axis current command iq_ref defined in the dq coordinate system has been considered as the current command vector, but the current command vector is a coordinate system synchronized with the rotor 21. Or a vector defined in a coordinate system equivalent thereto, and is not limited to a vector defined in a dq coordinate system having a d-axis and a q-axis.

<Dead time compensation in consideration of the polarity (whether addition or subtraction) of the compensation amount ΔVd>
Next, dead time compensation according to the present embodiment will be described, including a method of determining whether to add or subtract the compensation amount ΔVd obtained by the above-described method from the voltage command before compensation. Here, as described above, the electrical angle phase θ of the rotor 21 is in the range of −180 ° to + 180 °, and the reference of the electrical angle phase θ is 0 °. In addition, the rotation direction of the rotor 21 in which the value of the electrical angle phase θ increases (going from 0 ° to + 180 °) is positive, and the rotation in which the value of the electrical angle phase θ decreases (going from 0 ° to -180 °). The rotation direction of the child 21 is negative. A rotation speed ≧ 0 indicates that the rotor 21 rotates in the forward direction or is stopped, and a rotation speed <0 indicates that the rotor 21 rotates in the negative direction (the direction opposite to the forward direction). Refers to

  When the q-axis current command iq_ref ≧ 0, the d-axis current command id_ref <0, and the rotation speed ≧ 0, the relationship between each phase current and the electrical angular phase θ is as shown in FIG. 11A. In FIG. 11A, the horizontal axis is the time axis, and shows the time change of each phase current and the electrical angle phase θ. The U-phase, V-phase, and W-phase currents shown in FIG. 11A are out of phase by 120 °.

The section where the U-phase current is positive and the section where the electrical angle phase θ is positive have a phase difference of the initial phase difference θA + the phase Δθ of the current command vector, as shown in FIG. 11A. The initial phase difference θA is a phase difference between the timing when the U-phase current becomes 0 [A] and the timing when the electrical angular phase θ becomes 0 when the d-axis current command id_ref = 0. In the present embodiment, the initial phase difference θA is 90 °. The initial phase difference θA of 90 ° is predetermined by the system.

Further, as shown in FIG. 9, the phase Δθ is a phase amount that advances when d-axis current command id_ref = 0 when the d-axis current command id_ref takes a negative value other than 0. ) Can be calculated in advance.
Δθ = arctan (−id_ref (t) / iq_ref (t)) (3)

<< Dead time compensation for U phase >>
The above-described phase Δθ is calculated in advance by the timing generator 442 included in the dead time compensator 44 based on equation (3). Then, as shown in FIG. 11B, the timing generation unit 442 shifts the value of the electrical angle phase θ by adding the phase Δθ to the value of the electrical angle phase θ acquired by the position detection unit 41. . At this time, as shown in FIG. 11B, the waveform L1 (broken line) is shifted to the waveform L2 (solid line). The waveform L1 is the same as the waveform of the electrical angle phase θ shown in FIG. 11A.

  Further, as shown in FIG. 11C, the timing generation unit 442 adds the initial phase difference θA (= 90 °) to the electric angle phase θ shifted as described above to shift the value of the electric angle phase θ. At this time, as shown in FIG. 11C, the waveform L2 (broken line) is shifted to the waveform L3 (solid line), and the section where the waveform L3 has positive and negative values is the section where the U-phase current has positive and negative values. Matches.

  Therefore, when the value of the shifted electrical angular phase θ is positive, the timing generation unit 442 determines that the polarity of the U-phase current is positive, and the dead time compensating unit 44 sends the U-phase voltage command. The compensation amount ΔVd is added to Vu_ref. On the other hand, when the value of the shifted electrical angle phase θ is negative, the timing generation unit 442 determines that the polarity of the U-phase current is negative, and the dead time compensation unit 44 determines whether the U-phase voltage command The compensation amount ΔVd is subtracted from Vu_ref. That is, the timing generation unit 442 generates the timing of addition / subtraction of the compensation amount ΔVd based on the adjusted polarity of the electrical angle phase θ instead of the polarity of the U-phase current.

<< Dead time compensation for V phase >>
In addition, as shown in FIG. 12, the timing generator 442 shifts the electrical angle phase θ by subtracting 120 ° from the electrical angle phase θ shifted by adding the initial phase difference θA. At this time, as shown in FIG. 12, the waveform L3 (broken line) is shifted to the waveform L4 (solid line). Then, the section in which the electrical angle phase θ (waveform L4) after the shift has positive and negative values coincides with the section in which the V-phase current has positive and negative values.

  Therefore, when the value of the shifted electrical angular phase θ is positive, the timing generation unit 442 determines that the polarity of the V-phase current is positive, and in that case, the dead time compensation unit 44 Is added to the voltage command Vv_ref. On the other hand, when the value of the electrical angle phase θ after the shift is negative, the timing generation unit 442 determines that the polarity of the V-phase current is negative. The compensation amount ΔVd is subtracted from the voltage command Vv_ref. That is, the timing generation unit 442 generates the timing of addition / subtraction of the compensation amount ΔVd based on the adjusted polarity of the electrical angle phase θ instead of the polarity of the V-phase current.

<< Dead time compensation for W phase >>
In addition, as shown in FIG. 13, the timing generation unit 442 adds 120 ° to the electrical angle phase θ that has been shifted by adding the initial phase difference θA, thereby shifting the electrical angle phase θ. At this time, as shown in FIG. 13, the waveform L3 (broken line) is shifted to the waveform L5 (solid line). Then, the section in which the shifted electrical angle phase θ (waveform L5) has positive and negative values coincides with the section in which the W-phase current has positive and negative values.

  Therefore, when the value of the shifted electrical angular phase θ is positive, the timing generation unit 442 determines that the polarity of the W-phase current is positive, and the dead time compensation unit 44 determines whether the W-phase voltage command The compensation amount ΔVd is added to Vw_ref. On the other hand, when the value of the electrical angle phase θ after the shift is negative, the timing generation unit 442 determines that the polarity of the W-phase current is negative, and the dead time compensation unit 44 sends the W-phase voltage command. The compensation amount ΔVd is subtracted from Vw_ref. That is, the timing generation unit 442 generates the timing of addition / subtraction of the compensation amount ΔVd based on the adjusted polarity of the electrical angle phase θ instead of the polarity of the W-phase current.

<<< Rotational speed <0 >>>
FIG. 14 is an explanatory diagram showing the relationship between the U-phase current and the electrical angle phase θ when the rotation speed is <0. When the rotation speed <0, the change of the electrical angle phase θ with respect to the passage of time is opposite to the case where the rotation speed ≧ 0, and the electrical angle phase θ decreases with the passage of time. However, even in this case, the processing relating to the dead time compensation is the same as that in the case where the rotational speed ≧ 0.

<Effects of the present embodiment>
As described above, the motor drive control device 4 according to the present embodiment converts the voltage command into a PWM pulse, and switches on / off each switching element connected in series by the PWM pulse, thereby outputting a voltage to the motor 2. A motor drive control device 4 for controlling the drive of the motor 2 by giving the inverter 3 a voltage command based on a current command vector indicating a vector of a current to be followed by a current flowing through the motor 2, wherein the current command The vector is a vector defined in a coordinate system synchronized with the rotor 21 of the motor 2 or a coordinate system similar thereto, and is a dead time for the PWM inverter 3 to avoid simultaneous turning on of the series-connected switching elements. An error in the output voltage of the PWM inverter 3 caused by providing the time is compensated for. Determine the amount of compensation, comprising a dead time compensation section 44 for outputting the command voltage obtained by adding the compensation amount to the PWM inverter 3.

  The dead time compensator 44 includes a compensation amount determiner 441 for obtaining the absolute value of the compensation amount based on the magnitude of the current command vector, and an electrical angle phase θ of the rotor 21 based on the phase of the current command vector. And a timing generation section 442 that generates a timing for adding and subtracting the absolute value of the compensation amount based on the polarity of the electrical angle phase as a result of the adjustment.

  According to such a configuration, it is unnecessary to detect a phase current which is conventionally required for dead time compensation, and a two-phase current command (for example, each of d-axis and q-axis current commands) is changed to a three-phase current command. (For example, U-phase, V-phase, and W-phase current commands) is not required. In other words, dead time compensation can be easily performed without performing phase current detection or complicated coordinate conversion processing.

The current command vector is a composite vector of vector components of a d-axis current command and a q-axis current command in a dq coordinate system having a d-axis and a q-axis, and a predetermined fixed value of the compensation amount is represented by ΔVd , The q-axis current command is set to iq_ref (t) [A] using time t as a variable, the d-axis current command is set to id_ref (t) [A] using time t as a variable, and the current threshold is set to ith [ A]
The compensation amount determining unit 441 determines
ΔVd = ΔVd ′ × {(id_ref (t) ＾ 2 + iq_ref (t) ＾ 2) / ith
Is determined as the compensation amount.

  Thus, even if the d-axis current command and the q-axis current command have arbitrary values, the compensation amount ΔVd can be calculated by a simple calculation.

  When √ (id_ref (t) ＾ 2 + iq_ref (t) ＾ 2) is equal to or larger than the current threshold value ith, the compensation amount determining unit 441 determines the fixed value ΔVd ′ as the compensation amount ΔVd.

  Thus, the compensation amount ΔVd can be limited with the fixed value ΔVd ′ as the upper limit.

The current command vector is a composite vector of vector components of a d-axis current command and a q-axis current command in a dq coordinate system having a d-axis and a q-axis,
A position detection unit 41 that detects an electrical angle phase of the rotor 21 based on an output signal from the position sensor 6 that outputs a signal corresponding to the rotation position of the rotor 21 of the motor 2;
The timing generator 442 sets the q-axis current command to iq_ref (t) [A] using the time t as a variable, and sets the d-axis current command to id_ref (t) [A] using the time t as a variable.
Δθ = arctan (−id_ref (t) / iq_ref (t))
The phase Δθ of the current command vector is calculated, and the electrical angle phase is adjusted using the calculated phase Δθ.

  Thereby, the phase Δθ can be calculated for the d-axis current command whose value is not 0.

The position detection unit 41 detects the electrical angle phase in the range of −180 ° to + 180 °, and determines when the current command for the first phase of the motor 2 becomes 0 [A], When a phase difference at an electrical angle from the timing at which the electrical angle phase becomes 0 ° is defined as an initial phase difference, the timing generator 442 calculates the value of the electrical angular phase of the rotor 21 obtained by the position detector 41. The electric angle phase value is shifted by adding the phase Δθ to the electric angle phase, and the sign of the electric angle phase value shifted by adding the initial phase difference to the shifted electric angle phase is further added. , A timing for adding / subtracting the absolute value of the compensation amount of the first phase is generated.

  Accordingly, it is possible to generate the addition / subtraction timing of the compensation amount of the first phase by a simple process.

When the value of the electrical angle phase shifted by adding the initial phase difference is positive, the dead time compensating unit 44 outputs the voltage command of the first phase inputted to the dead time compensating unit 44. To the absolute value of the compensation amount,
When the value of the electrical angle phase shifted by adding the initial phase difference is negative, the dead time compensating unit 44 responds to the voltage command of the first phase input to the dead time compensating unit 44. Then, the absolute value of the compensation amount is subtracted.

  Thereby, dead time compensation of the first phase can be appropriately performed in accordance with the polarity of the electrical angle phase.

  In addition, the timing generation unit 442 adds the initial phase difference and shifts the value of the electrical angular phase in the second phase that is delayed by 120 ° in electrical angle with respect to the first phase of the motor 2. Is further subtracted by 120 °, and addition / subtraction of the compensation amount is determined based on the sign of the electrical angle phase value after the 120 ° subtraction.

  This makes it possible to generate the addition / subtraction timing of the compensation amount of the second phase by a simple process.

When the value of the electrical angle phase after the subtraction of 120 ° is positive, the dead time compensating unit 44 responds to the voltage command of the second phase input to the dead time compensating unit 44 by the compensation. Add the absolute value of the quantity,
When the value of the electrical angle phase after the subtraction of 120 ° is negative, the dead time compensator 44 determines the compensation amount of the compensation amount with respect to the second phase voltage command input to the dead time compensator 44. Subtract the absolute value.

  Thereby, dead time compensation of the second phase can be appropriately performed according to the polarity of the electrical angle phase.

  Further, in a third phase which is advanced by 120 ° in electrical angle with respect to the first phase of the motor 2, the timing generator 442 adds the initial phase difference and shifts the value of the electrical angular phase. Is further added to, and addition or subtraction of the compensation amount is determined based on the sign of the electrical angle phase value after the addition of 120 °.

  This makes it possible to generate the addition / subtraction timing of the compensation amount of the third phase by a simple process.

When the value of the electrical angle phase after the addition of 120 ° is positive, the dead time compensating unit 44 responds to the voltage command of the third phase inputted to the dead time compensating unit 44 by the compensation. Add the absolute value of the quantity,
If the value of the electrical angle phase after the addition of 120 ° is negative, the dead time compensating unit 44 responds to the voltage command of the third phase inputted to the dead time compensating unit 44 by the compensation amount of the compensation amount. Subtract the absolute value.

  Thus, dead time compensation of the third phase can be appropriately performed according to the polarity of the electrical angular phase.

<Supplement>
In the above description, the first phase, the second phase, and the third phase are described as the U phase, the V phase, and the W phase, respectively. For example, the first phase, the second phase, and the third phase The order may be the V phase, the W phase, and the U phase, or the W phase, the U phase, and the V phase.

  Although the electrical angle phase θ of the rotor 21 has been described as being in the range of −180 ° to + 180 °, it may be in the range of 0 ° to + 360 °. In this case, based on + 180 °, the range between + 180 ° and less than + 360 ° corresponds to positive, and the range from 0 ° to less than + 180 ° corresponds to negative, thereby performing the same dead time compensation as in the present embodiment. be able to.

  In the above, the calculation of the compensation amount ΔVd and the dead time compensation when the motor 2 is driven in three phases of the U phase, the V phase, and the W phase have been described. However, the method of the present embodiment is limited to a three-phase motor. Instead, the present invention can be applied to a case where a motor is driven in four or more phases. In this case, the same effect as that of the present embodiment can be obtained.

  The calculation of the compensation amount ΔVd and the dead time compensation described in the present embodiment can be applied to a system in which an error occurs in the output voltage to the motor due to the provision of the dead time, and this error needs to be compensated. Therefore, the motor to be drive-controlled may be a motor other than the BLDC motor. For example, the calculation of the compensation amount ΔVd and the dead time compensation described in the present embodiment can also be applied to drive control of an induction machine (induction motor).

  Note that the motor drive system 1 described in the present embodiment can also be expressed as follows. That is, the motor drive system 1 converts the voltage command into a PWM pulse with the motor 2 and switches on / off each of the switching elements (33u, 34u, etc.) connected in series by the PWM pulse, so that the voltage is applied to the motor 2 The motor drive control device 4 includes a PWM inverter 3 that outputs a signal, and a motor drive control device 4 that drives and controls the motor 2 using the PWM inverter 3. The motor drive control device 4 includes a dead time compensation unit 44 according to the present embodiment.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention. Further, the above-described embodiment and its modified examples can be arbitrarily combined as appropriate.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a motor drive control device that compensates for an output voltage error caused by providing a dead time in motor drive control.

      2 ... motor, 3 ... PWM inverter, 4 ... motor drive controller, 6 ... position sensor, 21 ... rotor, 33u, 33v, 33w ... switching element, 34u, 34v , 34w: switching element, 41: position detector, 44: dead time compensator, 441: compensation amount determiner, 442: timing generator

Claims (10)

By converting the voltage command into a PWM pulse and switching on / off each of the switching elements connected in series by the PWM pulse, the current flowing through the motor follows a PWM inverter that outputs a voltage to the motor. A motor drive control device that drives and controls the motor by giving the voltage command based on a current command vector indicating a vector,
The current command vector is a coordinate system synchronized with the rotor of the motor, or a vector defined in a coordinate system equivalent thereto,
In the PWM inverter, a compensation amount for compensating for an error in the output voltage of the PWM inverter, which is caused by providing a dead time for avoiding simultaneous ON of the switching elements connected in series, is calculated. A dead time compensating unit that outputs the added voltage command to the PWM inverter;
The dead time compensator,
A compensation amount determining unit that determines an absolute value of the compensation amount based on the magnitude of the current command vector;
A timing generator that adjusts the electrical angle phase of the rotor based on the phase of the current command vector, and generates a timing for adding or subtracting the absolute value of the compensation amount based on the polarity of the electrical angle phase as a result of the adjustment; When,
Having,
Motor drive control device. The current command vector is a composite vector of vector components of a d-axis current command and a q-axis current command in a dq coordinate system having a d-axis and a q-axis,
The predetermined fixed value of the compensation amount is ΔVd ′, the q-axis current command is iq_ref (t) [A] using time t as a variable, and the d-axis current command is id_ref ( t) [A] and the current threshold value is it [A],
The compensation amount determination unit,
ΔVd = ΔVd ′ × {(id_ref (t) ＾ 2 + iq_ref (t) ＾ 2) / ith
The motor drive control device according to claim 1, wherein ΔVd obtained by the above calculation is determined as the compensation amount.     The said compensation value determination part determines the said fixed value (DELTA) Vd 'as the said compensation amount (DELTA) Vd, when {(id_ref (t) ^ 2 + iq_ref (t) ^ 2) is more than the said current threshold value ith. Motor drive control device. The current command vector is a composite vector of vector components of a d-axis current command and a q-axis current command in a dq coordinate system having a d-axis and a q-axis,
A position detection unit that detects an electrical angle phase of the rotor based on an output signal from a position sensor that outputs a signal corresponding to a rotation position of the rotor of the motor,
The timing generation unit sets the q-axis current command to iq_ref (t) [A] using time t as a variable, and sets the d-axis current command to id_ref (t) [A] using time t as a variable.
Δθ = arctan (−id_ref (t) / iq_ref (t))
4. The motor drive control device according to claim 1, wherein the phase Δθ of the current command vector is calculated, and the electrical angle phase is adjusted using the calculated phase Δθ. 5. The position detection unit detects the electrical angle phase in a range from −180 ° to + 180 °,
When the phase difference in electrical angle between the timing when the current command for the first phase of the motor becomes 0 [A] and the timing when the electrical angle phase of the rotor becomes 0 ° is an initial phase difference. ,
The timing generation unit shifts the value of the electrical angle phase by adding the phase Δθ to the value of the electrical angle phase of the rotor acquired by the position detection unit, and shifts the electrical angle. 5. The timing according to claim 4, wherein a timing for adding or subtracting the absolute value of the compensation amount of the first phase is generated based on the sign of the value of the electrical angle phase that is further shifted by adding the initial phase difference to the phase. Motor drive control device. When the value of the electrical angle phase shifted by adding the initial phase difference is positive, the dead time compensating unit responds to the first phase voltage command input to the dead time compensating unit. And adding the absolute value of the compensation amount,
When the value of the electrical angular phase shifted by adding the initial phase difference is negative, the dead time compensating unit responds to the voltage command of the first phase input to the dead time compensating unit. The motor drive control device according to claim 5, wherein the absolute value of the compensation amount is subtracted.     In the second phase, which is delayed by 120 ° in electrical angle with respect to the first phase of the motor, the timing generation unit adds the initial phase difference and shifts the value of the electrical angular phase. 7. The motor drive control device according to claim 5, further comprising subtracting 120 ° and determining whether to add or subtract the compensation amount based on the sign of the electrical angle phase after the 120 ° subtraction. When the value of the electrical angle phase after the subtraction of 120 ° is positive, the dead time compensating unit responds to the voltage command of the second phase inputted to the dead time compensating unit by calculating the compensation amount of the second phase. Add the absolute value,
When the value of the electrical angle phase after the subtraction of 120 ° is negative, the dead time compensating unit responds to the voltage command of the second phase input to the dead time compensating unit by calculating the compensation amount of the second phase. The motor drive control device according to claim 7, wherein the absolute value is subtracted.   In the third phase, which is advanced by 120 ° in electrical angle with respect to the first phase of the motor, the timing generation unit calculates a value of the electrical angular phase shifted by adding the initial phase difference. 9. The motor drive control according to claim 5, further comprising adding 120 ° and determining whether to add or subtract the compensation amount based on the sign of the value of the electrical angle phase after the 120 ° addition. 10. apparatus. When the value of the electrical angle phase after the addition of 120 ° is positive, the dead time compensating unit responds to the voltage command of the third phase input to the dead time compensating unit by calculating the compensation amount of the third phase. Add the absolute value,
When the value of the electrical angle phase after the addition of 120 ° is negative, the dead time compensating unit responds to the voltage command of the third phase inputted to the dead time compensating unit by calculating the compensation amount of the compensation amount. The motor drive control device according to claim 9, wherein the absolute value is subtracted.

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