JP7444083B2 - motor control device - Google Patents

Description

The present invention relates to a motor control device.

2. Description of the Related Art Conventionally, motor control devices that share a circuit for driving a multiphase motor and a DC motor are known.

For example, the motor control device disclosed in Patent Document 1 drives a three-phase AC motor and two DC motors using one three-phase inverter drive circuit. Specifically, this motor control device is applied to a steering device of a vehicle, and drives a three-phase motor for electric power steering (EPS) and a DC motor used around the driver's seat. By sharing the power converter for the three-phase motor and the DC motor, we aim to downsize the power converter.

Patent No. 5614588

Two-phase stepping motors are sometimes used in actuators that require accurate positioning. For example, in the vicinity of the driver's seat of a vehicle, a two-phase stepping motor may be used to operate a head-up display or the like. When driving a two-phase stepping motor with an independent circuit, it is necessary to connect an H-bridge circuit to each phase, which requires a large number of switching elements. Furthermore, it is necessary to provide a dedicated microcomputer and noise prevention element. Patent Document 1 makes no mention of driving not only stepping motors but also two-phase motors.

The present invention was created in view of the above points, and an object of the present invention is to provide a motor control device that uses a common circuit for driving a multiphase motor and a two-phase motor.

The motor control device of the present invention includes a first circuit (68), a second circuit (67), and a control section (400). The first circuit is a two-system power conversion circuit that energizes a polyphase motor (800) having two sets of three-phase or more polyphase windings (801, 802). The second circuit is provided in the same housing (600) as the first circuit and energizes one or more two-phase motors (700) having mutually independent two-phase windings (714, 724). This is a power conversion circuit.

The control unit operates the first circuit and the second circuit, and commonly controls the operations of the polyphase motor and the two-phase motor. Therefore, in the motor control device of the present invention, a circuit for driving the multiphase motor and the two-phase motor is shared.

Further, the motor control device of the present invention applies voltage and current to the two-phase motor and the multi-phase motor. Preferably, the two-phase circuits in the second circuit are respectively connected to the circuits of each system in the first circuit. The two-phase motor is, for example, a two-phase stepping motor.

A set of high-potential side and low-potential side switching elements connected in series is defined as a leg. More preferably, each phase circuit in the second circuit is configured with one leg for each two-phase motor added to each system of inverters constituting the first circuit.

In other words, the control unit can drive the two-phase motor by driving the inverters of each system and turning on and off the switching elements of the added legs. This allows the number of switching elements for driving the two-phase motor to be halved. Further, by sharing the microcomputer and noise prevention element with the first circuit for the multiphase motor, special parts for the two-phase motor are not required.

FIG. 1 is a diagram of a column type EPS system to which the motor control device of this embodiment is applied. FIG. 1 is a diagram of a rack type EPS system to which the motor control device of the present embodiment is applied. FIG. 1 is a diagram of an SBW system to which the motor control device of this embodiment is applied. FIG. 2 is a configuration diagram of a first circuit and a second circuit according to the present embodiment. FIG. 1 is a schematic diagram showing the configuration of a three-phase double-winding rotating machine. FIG. 2 is a block diagram showing a control algorithm of the first embodiment. FIG. 3 is a waveform diagram showing three-phase voltage commands after operation when the two-phase stepping motor is stopped. FIG. 3 is a waveform diagram showing three-phase voltage commands after operation when driving a two-phase stepping motor. FIG. 7 is a block diagram showing a control algorithm of a second embodiment. FIG. 7 is a circuit diagram illustrating that the A-phase current is superimposed on the phase current of the connected phase of the first system of the three-phase motor as a principle for estimating the two-phase current value according to the second embodiment. FIG. 7 is a diagram showing the configuration of two-phase current estimation according to the second embodiment. FIG. 7 is a waveform diagram illustrating estimation of A-phase current according to the second embodiment.

Hereinafter, a plurality of embodiments of a motor control device according to the present invention will be described based on the drawings. The motor control device of each embodiment is applied to a vehicle's electric power steering system (hereinafter referred to as "EPS system") or steer-by-wire system (hereinafter referred to as "SBW system"), and functions as an EPS-ECU or SBW-ECU. Hereinafter, EPS-ECU or SBW-ECU will be collectively referred to as "ECU". In addition, each embodiment described below will be collectively referred to as the "present embodiment". Substantially the same configurations in the plurality of embodiments are given the same reference numerals, and description thereof will be omitted.

[System configuration]
First, with reference to FIGS. 1 to 3, the configuration of a system to which an ECU as a "motor control device" is applied will be described. 1 and 2 show an EPS system 901 in which a steering mechanism and a steering mechanism are mechanically connected. Among them, FIG. 1 shows a column type EPS system 901, and FIG. 2 shows a rack type EPS system 901. To distinguish between them, the column type EPS system is designated by the code 901C, and the rack type EPS system is designated by the code 901R. FIG. 3 shows an SBW system 902 in which the steering mechanism and steering mechanism are mechanically separated. In FIGS. 1 to 3, only one side of the wheel 99 is shown, and illustration of the wheel on the opposite side is omitted.

The EPS system 901 and the SBW system 902 commonly include a three-phase motor 800 as a "multiphase motor" and a two-phase stepping motor 700. The three-phase motor 800 in the EPS system 901 is a steering assist motor that assists the driver in steering, and the three-phase motor 800 in the SBW system 902 is a reaction force motor that provides a reaction force to the driver's steering. The two-phase stepping motor 700 is used, for example, as a motor that operates a head-up display that projects information on a windshield with high precision.

As shown in FIGS. 1 and 2, the EPS system 901 includes a steering wheel 91, a steering shaft 92, an intermediate shaft 95, a steering rack 97, and the like. The steering shaft 92 is enclosed in a steering column 93, and has one end connected to the steering wheel 91 and the other end connected to an intermediate shaft 95. The two-phase stepping motor 700 is provided inside the steering column 93, for example.

A steering rack 97 is provided at the end of the intermediate shaft 95 opposite to the steering wheel 91, which uses a rack and pinion mechanism to convert rotation into reciprocating motion and transmit the same. When the steering rack 97 reciprocates, the wheels 99 are steered via the tie rods 98 and knuckle arms 985. Moreover, universal joints 961 and 962 are provided in the middle of the intermediate shaft 95.

In the column type EPS system 901C shown in FIG. 1, the three-phase motor 800 is arranged on the steering column 93. The output torque of three-phase motor 800 is transmitted to steering shaft 92. The torque sensor 94 is provided in the middle of the steering shaft 92, detects torque based on torsional displacement of the torsion bar, and outputs a torque sensor value T_sns.

In the rack type EPS system 901R shown in FIG. 2, the three-phase motor 800 is arranged in a steering rack 97. The reciprocating movement of the steering rack 97 is assisted by the output torque of the three-phase motor 800. Torque sensor 94 detects torque transmitted to steering rack 97 and outputs torque sensor value T_sns.

The ECU 10 is activated by an ON/OFF signal from the vehicle switch 11 or the like. Note that the vehicle switch 11 corresponds to an ignition switch or a push switch of an engine vehicle, a hybrid vehicle, or an electric vehicle. Each signal to the ECU 10 is communicated using CAN, serial communication, etc., or sent as an analog voltage signal. Further, in this embodiment, the vehicle switch 11 may include a head-up display activation switch.

Next, as shown in FIG. 3, in the SBW system 902 in which the steering mechanism and the turning mechanism are mechanically separated, the intermediate shaft 95 does not exist in the EPS system 901. Driver input information such as the driver's steering torque or the angle of the steering wheel 91 is electrically transmitted to the steering motor 890 via the ECU 10. The rotation of steering motor 890 is converted into reciprocating motion of steering rack 97, and wheels 99 are steered via tie rods 98 and knuckle arms 985. Although not shown in FIG. 3, there is a steering motor ECU that drives the steering motor 890 in response to steering wheel input from the driver.

Furthermore, in the SBW system 902, the driver cannot directly sense reaction force to steering. Therefore, the ECU 10 controls the drive of the three-phase motor 800, which is a reaction force motor, and rotates the steering wheel 91 so as to apply a reaction force to the steering, thereby giving the driver an appropriate steering feeling. In the following description of the ECU 10, there is no difference between the EPS system 901 and the SBW system 902.

The control unit 400 applies voltage and current to a three-phase motor 800 having two three-phase winding sets and a two-phase stepping motor 700. Hereinafter, in the three-phase motor 800, a unit including a three-phase winding set and a three-phase inverter corresponding to the winding set will be referred to as a "system." The first circuit 68 is a power conversion circuit that energizes the three-phase motor 800 and includes two systems of three-phase inverters 681 and 682. The second circuit 67 is a power conversion circuit that energizes the two-phase stepping motor 700 and includes an A-phase leg 671 and a B-phase leg 672. Hereinafter, the term "leg" refers to a set of high-potential side and low-potential side switching elements connected in series.

The control unit 400 is composed of a microcomputer, a drive circuit, etc., and includes a CPU (not shown), a ROM, a RAM, an I/O, a bus line connecting these components, etc., and a physical memory device such as a ROM (i.e. , a readable non-temporary tangible recording medium) by executing a program stored in advance on a CPU, or control by hardware processing using a dedicated electronic circuit.

The control unit 400 operates the first circuit 68 and the second circuit 67 to commonly control the operations of the three-phase motor 800 and the two-phase stepping motor 700. The control unit 400 operates the first circuit 68 based on the torque sensor value T_sns detected by the torque sensor 94 and the vehicle speed V detected by the vehicle speed sensor 14, and controls the operation of the three-phase motor 800. The control unit 400 also operates the second circuit 67 to control the operation of the two-phase stepping motor 700.

[Configuration of first circuit and second circuit]
Next, with reference to FIG. 4, the configurations of the first circuit 68 and the second circuit 67 will be described. The first circuit 68 and the second circuit 67 are provided in the same housing 600 together with the control section 400. This makes it possible to downsize the ECU 10 and reduce the number of wiring components such as harnesses and connectors. Further, each of the A-phase and B-phase circuits in the second circuit 67 is constituted by one leg 671, 672 added to each system of inverters 681, 682 constituting the first circuit 68.

A three-phase motor 800 that is driven by the first circuit 68 has two three-phase winding sets 801 and 802. The three-phase winding set 801 of the first system is configured by windings 811, 812, 813 of U1 phase, V1 phase, and W1 phase connected at neutral point N1. A voltage is applied from the first system three-phase inverter 681 to the windings 811, 812, and 813 of each phase of the first system three-phase winding set 801.

The three-phase winding set 802 of the second system is configured by windings 821, 822, and 823 of U2 phase, V2 phase, and W2 phase connected at neutral point N2. Voltage is applied from the three-phase inverter 682 of the second system to the windings 821, 822, and 823 of each phase of the three-phase winding set 802 of the second system. Hereinafter, "first system three-phase winding set 801" and "second system three-phase winding set 802" will be omitted, and will be referred to as "first three-phase winding set 801" and "second three-phase winding set 801." 802".

As shown in FIG. 5, the two-system three-phase motor 800 is a double-winding rotating machine in which two three-phase winding sets 801 and 802 are coaxially provided. The two three-phase winding sets 801 and 802 have the same electrical characteristics, and are arranged, for example, on a common stator with an electrical angle of 30[deg] shifted from each other. In that case, the back electromotive force generated in each phase of the first system and the second system is calculated based on the voltage amplitude A, the rotation speed ω, and the phase θ, for example, using equations (1.1) to (1.3), (2 .1a) to (2.3a). In the portions described below, the phase θ can also be referred to as the electrical angle θ.

Eu1=-Aωsinθ...(1.1)
Ev1=-Aωsin(θ-120)...(1.2)
Ew1=-Aωsin(θ+120)...(1.3)
Eu2=-Aωsin(θ+30)...(2.1a)
Ev2=-Aωsin(θ-90)...(2.2a)
Ew2=-Aωsin(θ+150)...(2.3a)

Note that when the phase relationship of the two systems is reversed, for example, the phase of the U2 phase (θ+30) becomes (θ−30). In that case, the back electromotive force generated in each phase of the second system is expressed by equations (2.1b) to (2.3b) instead of equations (2.1a) to (2.3a). Furthermore, a phase difference equivalent to 30[deg] is generalized and expressed as (30±60×k)[deg] (k is an integer). Alternatively, the second system may be arranged in the same phase as the first system.

Eu2=-Aωsin(θ-30)...(2.1b)
Ev2=-Aωsin(θ+90)...(2.2b)
Ew2=-Aωsin(θ-150)...(2.3b)

FIG. 4 shows a configuration in which there is only one two-phase stepping motor 700 to be driven by the second circuit 67. The two-phase stepping motor 700 has two-phase windings, an A-phase winding 714 and a B-phase winding 724, which are independent from each other. Voltage pulses are alternately applied to the A-phase winding 714 and the B-phase winding 724 to supply direct current, and the rotor rotates by a constant angle in response.

The DC current applied to the A-phase winding 714 is referred to as A-phase current Idc1, and the DC current applied to the B-phase winding 724 is referred to as B-phase current Idc2. Further, the voltage between both terminals Tj1 and Tm1 of the A-phase winding 714 is denoted as Vx1, and the voltage between both terminals Tj2 and Tm2 of the B-phase winding 724 is denoted as Vx2.

The first circuit 68 includes two systems of three-phase inverters 681 and 682. The first system inverter 681 is connected to the U1 phase, V1 phase, and W1 phase windings 811, 812, and 813 of the first three-phase winding set 801. The second system inverter 682 is connected to the U2 phase, V2 phase, and W2 phase windings 821, 822, and 823 of the second three-phase winding set 802. The symbols of the components of the second system and the symbols of the currents are represented by replacing "1" in the symbols of the components and currents of the first system with "2".

The first system inverter 681 and the second system inverter 682 are connected in parallel to the power supply Bt. The inverters 681 and 682 of each system are connected to the positive electrode of the power source Bt via the high potential line Lp, and to the negative electrode of the power source Bt via the low potential line Lg. The power source Bt is, for example, a battery with a reference voltage of 12 [V]. The DC voltage input from the power supply Bt to the first system inverter 681 is referred to as an input voltage Vr1, and the DC voltage input to the second system inverter 682 is referred to as an input voltage Vr2.

The configuration of the first system will be described below as a representative. Regarding the configuration of the second system, the explanation of the first system is used. A capacitor C1 is provided on the power supply Bt side of the inverter 681 between the high potential line Lp and the low potential line Lg. In the current path between the power supply Bt and the capacitor C1, a power supply relay P1r is connected in series on the power supply Bt side, and a reverse connection protection relay P1R is connected in series on the capacitor C1 side.

The power supply relay P1r and the reverse connection protection relay P1R are constituted by a semiconductor switching element such as a MOSFET or a mechanical relay, and are capable of cutting off the power supply from the power supply Bt to the inverter 681 when turned off. The power supply relay P1r interrupts the current flowing in the direction when the electrodes of the power supply Bt are connected in the normal direction. The reverse connection protection relay P1R blocks current flowing when the electrodes of the power source Bt are connected in a direction opposite to the normal direction.

The inverter 681 converts the DC power of the power supply Bt into three-phase AC power through the operation of a plurality of bridge-connected high-potential side and low-potential side inverter switching elements IU1H, IU1L, IV1H, IV1L, IW1H, and IW1L. 1 three-phase winding set 801 is energized. Specifically, inverter switching elements IU1H, IV1H, and IW1H are upper arm elements provided on the high potential side of U1 phase, V1 phase, and W1 phase, respectively, and inverter switching elements IU1L, IV1L, and IW1L are upper arm elements provided on the high potential side of U1 phase, V1 phase, and W1 phase, respectively. This is a lower arm element provided on the low potential side of the W1 phase. Hereinafter, the upper arm element and lower arm element of the same phase will be collectively referred to as "IU1H/L, IV1H/L, IW1H/L" and the symbols of the inverter phase legs will be referred to as "IU1H/L, IV1H/L, IW1H/L".

Current sensors SAU1, SAV1, and SAW1 that detect phase currents Iu1, Iv1, and Iw1 flowing through each phase are installed between the lower arm elements IU1L, IV1L, and IW1L of each phase of the inverter 681 and the low potential line Lg. There is. Current sensors SAU1, SAV1, and SAW1 are composed of, for example, shunt resistors.

The second circuit 67 includes an A-phase leg 671 and a B-phase leg 672. The A-phase leg 671 and the B-phase leg 672 are connected to a first system inverter 681 and a second system inverter 682 in the first circuit 68, respectively. Specifically, the A-phase leg 671 is configured by a pair of high-potential side switching element MU1H and low-potential side switching element MU1L added to the first system inverter 681. The B-phase leg 672 is configured by a pair of high-potential side switching element MU2H and low-potential side switching element MU2L added to the second system inverter 682.

"Adding a leg" to the inverters 681, 682 means that a pair of high potential side and low potential side switching elements are connected between the high potential line Lp and the low potential line Lg common to the inverters 681, 682. It means to be done. The A-phase leg 671 and B-phase leg 672 added to the inverters 681 and 682 are also referred to as "additional legs." The high-potential side and low-potential side switching elements in the A-phase leg 671 and the B-phase leg 672 are collectively written as "MU1H/L, MU2H/L" for the additional legs. Further, the points between the high-potential side and low-potential side switching elements in the additional leg are referred to as "leg midpoints M1 and M2."

The switching elements IU1H/L, IV1H/L, IW1H/L, IU2H/L, IV2H/L, IW2H/L of each system inverter 681 and 682, and the switching elements MU1H/L and MU2H/L of the additional legs are, for example, It is a MOSFET. In addition, the switching element may be a field effect transistor, IGBT, or the like other than MOSFET. Here, the current flowing through the two-phase stepping motor 700 is smaller than the phase current flowing through the three-phase motor 800. Therefore, a switching element having a smaller current capacity than the inverter switching element may be used for the additional leg.

A branch point side terminal Tj1, which is one terminal of the A-phase winding 714, is connected to the branch point Ju1 of the U1 phase current path of the first three-phase winding set 801. The leg side terminal Tm1, which is the other terminal of the A-phase winding 714, is connected to the leg midpoint M1 of the A-phase leg 671. Similarly, a branch point side terminal Tj2, which is one terminal of the B-phase winding 724, is connected to the branch point Ju2 of the U2-phase current path of the second three-phase winding set 802. The leg side terminal Tm2, which is the other terminal of the B-phase winding 724, is connected to the leg midpoint M2 of the B-phase leg 672.

The phase to which the A-phase winding 714 and the B-phase winding 724 are connected in the three-phase winding sets 801 and 802 of each system of the three-phase motor 800 is defined as a "connected phase." For example, "U1" in the code "MU1H/L" of the switching element of the additional leg means the U1 phase which is the connected phase of the first system. In the configuration example of FIG. 4, the U1 phase of the first system and the U2 phase of the second system are connected phases, but any phase in each system may be the connected phase.

Next, the relationship between the currents flowing through the three-phase winding sets 801 and 802 and the two-phase windings 714 and 724 will be described using the first three-phase winding set 801 and the A-phase winding 714 as representatives. With respect to the phase currents Iu1, Iv1, and Iw1 flowing through the inverter 681, the phase currents flowing through the three-phase winding set 801 are written as Iu1#, Iv1#, and Iw1#. In the example of FIG. 4, a part of the phase current Iu1 is separated as the A-phase current Idc1 at the branch point Ju1 of the U1 phase current path, which is the connected phase.

The relationship between the inverter phase currents Iu1, Iv1, Iw1 flowing to the inverter 681 side of the branch point Ju1 and the motor phase currents Iu1#, Iv1#, Iw1# flowing to the three-phase winding set 801 side of the branch point Ju1 is as follows. It is represented by formulas (3.1) to (3.4). The relationship in equation (3.4) is used to estimate the A-phase current Idc1 according to the second embodiment.

Iu1#=-Iv1-Iw1...(3.1)
Iv1#=Iv1...(3.2)
Iw1#=Iw1...(3.3)
Idc1=Iu1-Iu#1=Iu1+Iv1+Iw1...(3.4)

In the A-phase winding 714, the direction of current Idc1 flowing from branch point side terminal Tj1 to leg side terminal Tm1 is defined as a positive direction, and the direction of current Idc1 flowing from leg side terminal Tm1 to branch point side terminal Tj1 is defined as a negative direction. The sign of the inter-terminal voltage Vx1 is positive when the voltage at the branch point side terminal Tj1 is higher than the voltage at the leg side terminal Tm1. The same applies to the B-phase winding 724.

The control unit 400 controls the phase current detection values Iu1, Iv1, Iw1, Iu2, Iv2, Iw2 detected by the current sensors SAU1, SAV1, SAW1, SAU2, SAV2, and SAW2 of each system, and the electrical angle θ of the three-phase motor 800. Based on this, the operation of the three-phase motor 800 is controlled. Further, the control unit 400 outputs gate signals to the inverters 681 and 682 of each system while operating the center voltage of the three-phase voltage command value of the three-phase motor 800. At the same time, control unit 400 outputs a two-phase motor drive command to turn on one of switching elements MU1H/L of A-phase leg 671 and switching element MU2H/L of B-phase leg 672, and turn off the other.

For example, when energizing the A-phase winding 714 in the positive direction, the control unit 400 turns on the low-potential side switching element MU1L of the A-phase leg 671, turns off the high-potential side switching element MU1H, and turns on the voltage at the branch point Ju1. is set higher than the voltage at the leg midpoint M1, and the inter-terminal voltage Vx1 is adjusted to a positive value. Further, when energizing the A-phase winding 714 in the negative direction, the control unit 400 turns on the high-potential side switching element MU1H of the A-phase leg 671, turns off the low-potential side switching element MU1L, and turns on the branch point Ju1. The voltage is set lower than the voltage at the leg midpoint M1, and the inter-terminal voltage Vx1 is adjusted to a negative value.

The control unit 400 sequentially adjusts the terminal-to-terminal voltages Vx1 and Vx2 of the A-phase and B-phase, and alternately applies voltage pulses to the A-phase winding 714 and the B-phase winding 724 in an overlapping manner. The stepping motor 700 is rotated by a constant angle. The rotor rotation angle is calculated with high accuracy based on counting the number of voltage pulses applied to each phase. Furthermore, since the two-phase stepping motor 700 is brushless and the brushes do not wear out, the number of durable uses is increased compared to a brushed DC motor.

In the conventional technique in which one two-phase stepping motor 700 is driven by an independent circuit, a total of four legs are required because an H-bridge circuit is connected to each phase. In contrast, in this embodiment, one two-phase stepping motor 700 can be driven by a total of two additional legs 671 and 672, so the number of switching elements can be halved. Furthermore, by sharing the microcomputer and noise prevention element with the first circuit 68 for the three-phase motor 800, special parts for the two-phase stepping motor 700 are not required.

[Motor drive control configuration]
Next, two embodiments of control configurations in which the control unit 400 drives the three-phase motor 800 and the two-phase stepping motor 700 will be described. In the first embodiment, the control unit 400 controls the current flowing through the two-phase windings 714 and 724 of the two-phase stepping motor 700 in a feedforward manner. In the second embodiment, the control unit 400 operates the voltages Vx1 and Vx2 between the terminals of the two-phase windings 714 and 724 based on the currents that actually flow through the two-phase windings 714 and 724, and controls the current. That is, feedback control is performed using the current of the two-phase stepping motor 700.

(First embodiment)
The motor drive control configuration according to the first embodiment will be described with reference to FIGS. 6 to 8. FIG. 6 shows the control algorithm of the first embodiment. The upper part of FIG. 6 shows a block that outputs a first system of gate signals, and the lower part of FIG. 6 shows a block that outputs a second system of gate signals. Regarding the codes of blocks of both systems, "481, 482" and "491, 492" are assigned codes for each system. For other blocks, the distinction between codes for each system is omitted and common codes are given. Regarding the current or voltage symbol, the suffix "1" indicates the value of the first system, and "2" indicates the value of the second system. In the following description, symbols for the current and voltage of the first system will be described as representative symbols.

The control unit 400 includes a q-axis current deviation calculator 43, a q-axis current controller 44, a d-axis current deviation calculator 45, a d-axis current controller 46, a dq/three-phase converter 47, and a neutral point for each system. It includes voltage operation units 481 and 482 and PWM modulators 491 and 492.

The q-axis current deviation calculator 43 calculates a q-axis current deviation ΔIq1 between the q-axis current command Iq1 ^* and the fed-back q-axis current Iq1. The q-axis current controller 44 calculates the q-axis voltage command Vq1* so that the q-axis current deviation ΔIq1 approaches 0, in other words, so that the q-axis current Iq1 follows the q-axis current command ^{Iq1 *} . Note that the q-axis current command Iq1 ^* is calculated by torque control, position control, speed control, current control, voltage control, etc. Further, the current may be limited to a current limit value or less if necessary.

The d-axis current deviation calculator 45 calculates a d-axis current deviation ΔId1 between the d-axis current command Id1 ^* and the fed-back d-axis current Id1. The d-axis current controller 46 calculates the d-axis voltage command Vd1* so that the d-axis current deviation ΔId1 approaches 0, in other words, so that the d-axis current Id1 follows the d-axis current command ^{Id1 *} .

The dq/three-phase converter 47 coordinately transforms the dq-axis voltage commands Vq1 ^* , Vd1 ^* into three-phase voltage commands Vu1 ^* , Vv1 ^* , Vw1 ^* . Note that illustration of the signal of the electrical angle θ input to the dq/three-phase conversion unit 47 for coordinate conversion calculation is omitted. The center voltage of the three-phase voltage commands Vu1 ^* , Vv1 ^* , and Vw1 ^* output by the dq/three-phase converter 47 is 0 [V].

The center voltage operating section 481 of the first system operates the center voltage of the three-phase voltage commands Vu1 ^* , Vv1 ^* , and Vw1 ^* using the offset voltage Vm1 ^* . In other words, the voltage at the neutral point N1 of the three-phase winding set 801 is shifted. FIG. 7 shows waveforms of the three-phase voltage commands Vu1 ^* #, Vv1 ^* #, and Vw1 ^* # after operation when only the three-phase motor 800 is driven and the two-phase stepping motor 700 is stopped. The horizontal axis represents one period of the electrical angle θ. For example, when the input voltage Vr1 is 12 [V], the center voltage is offset to 6 [V].

FIG. 8 shows waveforms of the three-phase voltage commands Vu1 ^* #, Vv1 ^* #, and Vw1 ^* # after operation when driving the two-phase stepping motor 700 while driving the three-phase motor 800. The upper part of FIG. 8 shows the waveform when the A-phase winding 714 is energized in the positive direction, and the lower part of FIG. 8 shows the waveform when the A-phase winding 714 is energized in the negative direction. These waveform diagrams are treated as a set of related diagrams. The thick solid arrow in FIG. 8 represents the voltage applied to the A-phase winding 714.

When energizing the A-phase winding 714 in the positive direction, the control unit 400 turns on the low-potential side switching element MU1L of the A-phase leg 671. Further, the control unit 400 calculates the offset voltage Vm1 ^* so that the post-operation voltage command Vu1 ^* # of the U1 phase, which is the connected phase, is constant at a voltage VH close to 12 [V] (for example, 10 [V]). As a result, a positive voltage is applied to the A-phase winding 714, as indicated by the upward thick solid arrow. Note that the sine wave amplitudes of the post-operation voltage commands Vv1 ^* # and Vw1 ^* # of the V1 phase and W1 phase are √3 times the amplitude before the operation (that is, the amplitude of the line voltage).

When energizing the A-phase winding 714 in the negative direction, the control unit 400 turns on the high-potential side switching element MU1H of the A-phase leg 671. Further, the control unit 400 calculates the offset voltage Vm1 ^* so that the post-operation voltage command Vu1 ^* # of the U1 phase, which is the connected phase, is constant at a voltage VL close to 0 [V] (for example, 2 [V]). As a result, a negative voltage is applied to the A-phase winding 714, as shown by the downward thick solid arrow.

The first system PWM modulator 491 performs PWM modulation on the three-phase voltage command after center voltage manipulation, and generates a gate signal. The gate signal output by the first system PWM modulator 491 is input to each gate of the switching elements IU1H/L, IV1H/L, and IW1H/L of the first system inverter 681.

Similar control is performed for the second system, and the B-phase inter-terminal voltage Vx2 is manipulated to a positive voltage or a negative voltage by the offset voltage Vm2 ^* calculated by the center voltage manipulation section 482. The gate signal output from the second system PWM modulator 492 is input to each gate of the switching elements IU2H/L, IV2H/L, and IW2H/L of the second system inverter 682.

The PWM modulators 491 and 492 of each system output gate signals with a predetermined electrical angle phase shift, so that voltage pulses are alternately applied to the A-phase winding 714 and the B-phase winding 724 of the two-phase stepping motor 700. be done. Assuming that the load on the two-phase stepping motor 700 does not change and the operating environment is stable, it is estimated that the theoretical current flows through the A-phase winding 714 and the B-phase winding 724. In this manner, in the first embodiment, the currents flowing through the two-phase windings 714 and 724 are controlled in a feedforward manner.

(Second embodiment)
A motor drive control configuration according to the second embodiment will be described with reference to FIGS. 9 to 12. FIG. 9 shows the control algorithm of the second embodiment. In addition to the control algorithm of the first embodiment shown in FIG. 6, in FIG. 9, calculation of offset voltages Vm1 ^* and Vm2 ^* for manipulating the center voltage of the three-phase voltage command value in the center voltage operation units 481 and 482 is added. The following configuration is shown below. The control unit 400 of the second embodiment turns on either the high-potential side or low-potential side switching elements of the A-phase leg 671 and the B-phase leg 672, and also controls the phase voltage command value of the three-phase motor 800. By adjusting the offset amount for the center voltage, the inter-terminal voltages Vx1 and Vx2 to be applied to each phase winding 714 and 724 of the two-phase stepping motor 700 are determined.

In addition to the configuration shown in FIG. 6, the control unit 400 includes an A-phase current deviation calculator 551, an A-phase current controller 561, a B-phase current deviation calculator 552, and a B-phase current controller 562. Phase A will be explained as a representative example. The A-phase current deviation calculator 551 calculates the A-phase current deviation ΔIdc1 between the A-phase current command value Idc1 ^* and the fed-back A-phase current value Idc1. Hereinafter, depending on the context, the presence or absence of a "value" may coexist, such as "A-phase current" and "A-phase current value." Basically, "current value" is a word emphasizing that it is a "value," but it is not a strict distinction.

The A-phase current controller 561 calculates the offset voltage Vm1 ^* of the first system so that the A-phase current deviation ΔIdc1 approaches 0, in other words, so that the A-phase current Idc1 follows the A-phase current command Idc1 ^* , The center voltage of the phase voltage command values Vu1 ^* , Vv1 ^* , and Vw1 ^* is manipulated. As described above, the A-phase inter-terminal voltage Vx1 changes by operating the center voltage in accordance with ON/OFF of the switching element MU1H/L of the A-phase leg 671. Then, the A-phase current value Idc1 changes in accordance with the A-phase inter-terminal voltage Vx1. The A-phase current value Idc1 after the change is fed back to the A-phase current deviation calculator 551.

In this way, the control unit 400 controls the A-phase current value Idc1 and the B-phase current value Idc2 by feedback control using the center voltage of the phase voltage command values of the three-phase winding sets 801 and 802 of each system as the manipulated variable. This control is based on the idea of accurately controlling the torque of the two-phase stepping motor 700, similar to the control of the three-phase motor 800.

Here, the two-phase current values Idc1 and Idc2 fed back may be detected values or estimated values. That is, the control unit 400 applies voltage to the three-phase winding sets 801 and 802 of each system based on the detected value or estimated value of the current flowing through each phase of the two-phase motor. In a configuration using two-phase current detection values, for example, a current sensor is provided in each current path of the A-phase winding 714 and the B-phase winding 724. In this configuration, since the control unit 400 does not perform estimation calculations for the current values Idc1 and Idc2, the calculation load is reduced. On the other hand, the configuration in which the control unit 400 estimates the current values Idc1 and Idc2 does not require a current sensor for two-phase current, which is advantageous in terms of installation space and component cost reduction.

The principle of estimating the A-phase current value Idc1 will be described with reference to FIG. 10. Due to the duty operation of the first system inverter 681, the U1 phase current Iu1# flows from the V1 phase or the W1 phase via the neutral point N1 to the low potential line Lg along the path indicated by the thick solid arrow. Further, when the high-potential side switching element MU1H of the A-phase leg 671 is turned on and the low-potential side switching element MU1L is turned off, the A-phase current Idc1 flows along the path indicated by the thick broken line arrow.

Therefore, a current Iu1 in which the A-phase current Idc1 is superimposed on the U1-phase current Iu1# flows through the current sensor SAU1. That is, a value obtained by superimposing A-phase current Idc1 on U1-phase current Iu1# is detected as U1-phase current detection value Iu1 by current sensor SAU1. Therefore, the control unit 400 estimates the A-phase current Idc1 by extracting the A-phase current Idc1 from the U1 phase current detection value Iu1, which is the connected phase. Similarly, the control unit 400 estimates the B-phase current Idc2 by extracting the B-phase current Idc2 from the U2 phase current detection value Iu2, which is the connected phase.

Next, with reference to FIGS. 11 and 12, a specific configuration in which the control unit 400 estimates the A-phase current Idc1 and the B-phase current Idc2 will be described. As shown in FIG. 11, the control section 400 includes a two-phase current estimation section 50. For example, the sum of the three-phase currents Iu1#, Iv1#, and Iw1# flowing through the phase windings 811, 812, and 813 of the first three-phase winding set 801 is theoretically zero. Therefore, as shown in equation (3.4) above, the difference between the sum of the three-phase detected phase current values Iu1, Iv1, and Iw1 and zero corresponds to the A-phase current value Idc1.

FIG. 12 shows the waveform of the U1 phase current detection value Iu1 on which the positive A phase current value Idc1 is superimposed at the start of energization of the two-phase stepping motor 700. When energization is started at time ts, the A-phase current value Idc1 increases due to an inrush current, and reaches its peak at time tp. After time tp, the A-phase current value Idc1 gradually decreases.

Therefore, the two-phase current estimation unit 50 adds the U1 phase current detection value Iu1, the V1 phase current detection value Iv1, and the W1 phase current detection value Iw1 for the first system to calculate the A phase current estimation value Idc1_est. Similarly, the two-phase current estimation unit 50 adds the detected U2-phase current value Iu2, the detected V2-phase current value Iv2, and the detected W2-phase current value Iw2 for the second system to calculate the estimated B-phase current value Idc2_est. In this way, the control unit 400 estimates the sum of the three-phase current detection values in each system of the first circuit 68 as the current values Idc1 and Idc2 flowing through each phase of the two-phase stepping motor 700.

Note that when the load of the two-phase stepping motor 700 changes or the operating environment such as the ambient temperature changes, the two-phase current values Idc1 and Idc2 usually change to the same extent, and the offset voltages Vm1 ^* , Vm2 ^* are values that are correlated with each other. However, even if the two-phase current values Idc1 and Idc2 differ due to characteristic variations between the A-phase winding 714 and the B-phase winding 724, the offset voltages Vm1 ^* and Vm2 ^* of the two systems and the three-phase voltage after operation Arbitration may be performed through cooperative control or the like between the two systems so that the command values do not deviate by more than a predetermined value.

In addition to using the sum of the phase current detection values of the three phases, the two-phase current estimation unit 50 also uses a method of calculating the difference between the phase current detection value of the connected phase and the phase current command value, or a method of calculating the DC component by filtering. The two-phase current values Idc1 and Idc2 may be estimated using an extraction method or the like.

(Other embodiments)
(a) The two-phase motor is not limited to a stepping motor, and may be any motor having mutually independent two-phase windings. Further, the number of two-phase motors is not limited to one, but two or more may be provided. For example, when two two-phase motors are provided, two A-phase legs are added to the first system inverter 681 and two B-phase legs are added to the second system inverter 682 as the second circuit. In other words, the A-phase and B-phase circuits in the second circuit are composed of "one leg per two-phase motor" added to the first system inverter 681 and the second system inverter 682. Ru.

Furthermore, the connection point side terminal of the A-phase winding of each two-phase motor is connected to the phase current path of the same phase or different phase of the first three-phase winding set 801. The connection point side terminal of the B-phase winding of each two-phase motor is connected to the same phase or different phase current path of the second three-phase winding set 802. The control unit 400 commonly controls the operations of the polyphase motor and each two-phase motor.

(b) In an example where the present invention is applied to a vehicle EPS system or SBW system, the two-phase stepping motor may be used in a tilt actuator, a telescopic actuator, etc. in addition to a head-up display. By using a two-phase stepping motor, position accuracy is improved compared to using a general DC motor, and the brushless design increases the number of durable uses. In addition to the steering assist motor and the reaction force motor, a brake hydraulic pump motor may be used as the multiphase motor. Furthermore, the present invention may be applied to motors other than those for vehicles.

(c) A "polyphase motor" is not limited to a three-phase motor, but may be a motor with four or more phases. In that case, the "sum of current detection values of three phases in each system" in the second embodiment is generalized to "sum of current detection values of all phases in each system".

(d) In the two-system circuit configuration shown in FIG. 4, there is no need to provide a power supply relay or a reverse connection protection relay. Furthermore, a three-phase motor relay or a two-phase motor relay may be added, or an LC filter circuit as a noise prevention element may be added to the input section. The two systems of inverters 681 and 682 may be connected to separate power sources instead of being connected to a common power source Bt.

The present invention is not limited to such embodiments, and can be implemented in various forms without departing from the spirit thereof.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

10...ECU (motor control unit),
400...control unit,
600... housing,
67... second circuit,
68...first circuit,
700...Two-phase stepping motor (two-phase motor),
714, 724...Two-phase (A phase, B phase) winding,
800...Three-phase motor (polyphase motor),
801, 802... Three-phase winding set (polyphase winding set).

Claims (8)

a first circuit (68) that is a two-system power conversion circuit that energizes a polyphase motor (800) having two three-phase or more polyphase winding sets (801, 802);
A power conversion circuit that is provided in the same casing (600) as the first circuit and energizes one or more two-phase motors (700) having mutually independent two-phase windings (714, 724). a certain second circuit (67);
a control unit (400) that operates the first circuit and the second circuit and commonly controls operations of the multiphase motor and the two-phase motor;
A motor control device comprising: The motor control device according to claim 1, wherein a voltage is applied to the two-phase motor and the multi-phase motor, and a current is passed through the two-phase motor and the multi-phase motor. 3. The motor control device according to claim 2, wherein the two-phase circuits in the second circuit are respectively connected to circuits of each system in the first circuit. If a set of high-potential side and low-potential side switching elements connected in series is defined as a leg,
Each phase circuit in the second circuit is constituted by one leg for each two-phase motor added to each system of inverters constituting the first circuit,
One terminal of each phase winding of the two-phase motor is connected to a phase current path of one phase in the polyphase winding set of the corresponding system, and the other terminal of each phase winding of the two-phase motor 4. The motor control device according to claim 3, wherein is connected between a high potential side switching element and a low potential side switching element in a leg constituting the second circuit. The control unit includes:
Turning on either a high-potential side switching element or a low-potential side switching element of a leg constituting the second circuit, and adjusting an offset amount with respect to a center voltage of a phase voltage command value of the multiphase motor. The motor control device according to claim 4, wherein the voltage to be applied to each phase winding of the two-phase motor is determined. The motor control device according to claim 5, wherein the control unit applies voltage to the polyphase winding set of each system based on a detected value or an estimated value of the current flowing through each phase of the two-phase motor. The control unit includes:
7. The motor control device according to claim 6, wherein the sum of detected current values of all phases in each system of the first circuit is estimated as a current value flowing through each phase of the two-phase motor. The polyphase motor is a steering assist motor that assists the driver in steering in an electric power steering system of a vehicle, or a reaction force motor that applies a reaction force to the driver's steering in a steer-by-wire system,
The motor control device according to claim 1, wherein the two-phase motor is a two-phase stepping motor.

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